CA1073959A - Staggered nozzle array - Google Patents
Staggered nozzle arrayInfo
- Publication number
- CA1073959A CA1073959A CA268,536A CA268536A CA1073959A CA 1073959 A CA1073959 A CA 1073959A CA 268536 A CA268536 A CA 268536A CA 1073959 A CA1073959 A CA 1073959A
- Authority
- CA
- Canada
- Prior art keywords
- nozzles
- row
- respect
- nozzle
- rows
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/135—Nozzles
- B41J2/14—Structure thereof only for on-demand ink jet heads
- B41J2/1433—Structure of nozzle plates
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
- B41J2/135—Nozzles
- B41J2/145—Arrangement thereof
- B41J2/155—Arrangement thereof for line printing
Abstract
STAGGERED NOZZLE ARRAY
Abstract of The Disclosure A jet printer includes a nozzle plate having at least two rows of nozzles, with the nozzles in one row being laterally staggered with respect to the nozzles in another row. The jets emanating from the respective rows of nozzles are directed in non-parallel trajectories to form at least a portion of a single line of dots at a time on a printing medium, with the jets from a given row forming non-adjacent dots on the printing medium. In practice, the nozzle plate is comprised of a semiconductor substrate, for example silicon, with the exit aperture of each of the nozzles in at least one row being axially misaligned with respect to the longitudinal center axis of their respective entrance apertures, resulting in a non-normal jet trajectory with respect to the plane of the nozzle plate.
Abstract of The Disclosure A jet printer includes a nozzle plate having at least two rows of nozzles, with the nozzles in one row being laterally staggered with respect to the nozzles in another row. The jets emanating from the respective rows of nozzles are directed in non-parallel trajectories to form at least a portion of a single line of dots at a time on a printing medium, with the jets from a given row forming non-adjacent dots on the printing medium. In practice, the nozzle plate is comprised of a semiconductor substrate, for example silicon, with the exit aperture of each of the nozzles in at least one row being axially misaligned with respect to the longitudinal center axis of their respective entrance apertures, resulting in a non-normal jet trajectory with respect to the plane of the nozzle plate.
Description
~073959 : ~
1 Background of The Invention
1 Background of The Invention
2 In nozzle per spot ink jet printers, the print
3 quality is dependent upon the effective center-to-center
4 distance of adjacent nozzles in an array. In known nozzle technologies relatively close center-to-center distanGesare 6 achievable, for example, on the order of 3 or 4 mils. This, 7 however, results in a fragile array due to the close center-8 ing of the respective nozzles.
9 The use of laterally staggered multiple arrays as set forth in U.S. Reissue Patent RE. 28,219 to Taylor et al.
11 provides an alternative to fabricating nozzles on close 12 centers, while introducing at least two problems.
13 The first problem is that additional timing networks 14 are utilized to permit the staggered array of RE. 28,219 to effectively emulate one line of nozzles. That is, for a 16 staggered array of two rows of nozzles, for example, the print 17 signal applied to the upper row of nozzles must be delayed or 18 advanced with respect to the print signal applied to the lower 19 row of nozzles dependent upon the direction of travel of the printing medium, such that the droplets from the two rows of 21 nozzles are sequentially applied a row at a time to form a 22 single line on the printing medium.
23 The second problem deals with the gutter structure 24 and required deflection voltages. If a single gutter is used, then non-printing droplets from both rows of nozzles must be 26 deflected to the single gutter. This requires a higher def-27 lection voltage than is used for a single row of nozzles due 28 to the different and substantially parallel droplet trajector-. . .
. . .
~073~59 1 ies from the two rows. Two gutters may be used as in Taylor et al, but this results in a more complex physical 3 structure for the printer.
4 According to the present invention an ink jet printer including a staggered nozzle array is disclosed, in 6 which the a~ove-named problems are eliminated or at least 7 substantially reduced. This is accomplished by having the 8 droplet streams from at least one of the rows emanate off-g normal with respect to the plane of the nozzle plate, result-ing in the droplets from the respective rows concurrently 11 converging in non-parallel tra~ectories to form a single line 12 at a given time on the printing medium. Accordingly, the need 13 for complex timing circuitry to achieve line at a time printing 14 from a staggered nozzle array i9 substantially reduced. Thi5 is so, since all of the dot positions of a line which i9 to be 16 printed, are printed concurrently by the ~ets emanating from 17 the respective rows of nozzles, rather than sequentially, that 18 i9 by a row of nozzles at a time, as disclosed by Taylor et al.
19 Further, since the gutter is rel-atively close to the printing medium, the upper set of droplet streams require only 21 slightly more deflection than the lower set of droplet streams 22 in order to gutter the respective droplets. This is so, since 23 the respective droplet streams are converging towards the 24 respective dot positions of the line as they approach the printing medium. Therefore, a deflection voltage may be used 26 for the respective droplet streams which is essentially the 27 same as would be used for a slngle row of streams, since each 28 droplet stream is substantially the same distance from the gutter ns they near the printing medlum, resulting in the 2 droplets from the respective streams striking the gutter 3 relatively close to one another.
.
~ 4 Summary of The Invention According to the present invention a jet printer 6 is disclosed which includes a nozzle pl-ate comprised of a 7 semiconductor substrate having at least two rows of nozzles 8 formed therein> with the nozzles in one row being laterally 9 staggered with respect to the nozzles ln another row. Each nozzle has entrance and exit apertures of different cross-11 sectional area, with the exit aperture of each of the nozzles 12 in at least one row belng axially misaligned with respect to 13 the longitudlnal center axis of their respective entrance 14 apertures. A method of printing at least a portion of a line at a time on a printing medium is accomplished, wherein the 16 line is comprised of a plurality of dot posltions. The jets 17 from one row of nozzles are directed towards a selected first 18 group of non-adjacent dot positions of said line on the print-19 ing medium, and concurrent therewith the jets from another row of nozzles are directed in a non-parallel trajectory with 21 respect to the trajectory of the jets from the one row of 22 nozzles, towards a selected second group of non-adjacent dot 23 positions of the line on sald prlnting medium.
24 Brief Description of the DrawinRs 25 - FIG. 1 i8 a sectional side view of a staggered 26 nozzle arra-y for printing a line at a time according to the 27 present invention;
1 FIG. 2 18 a perspectlve v$ew oL a staggercd nozzle 2 array according to the present invention;
3 FIG. 3 is a front view of a charge electrode 4 structure uhich may be utilized in the practice of the present inventlon; -6 FIG. 4 is a back to front view of a membrane silicon 7 nozzle;
8 FIGS. 5 and 6 are cross-sectional views illustrating 9 fluid 10w in normal and reverse directions, respectively, through a tapered nozzle;
11 FIG. 7 is a cross-sectional view of a membrane 12 silicon nozzle in which the exit aperture of the nozzle is 13 offset with respect to the longitudinal center axis of the .14 entrance aperture of the nozzle, and which illustrates fluid flow from the nozzle;
16 FIGS. 8A-8J represent sequential cross-sectional 17 views of a silicon wafer processed in accordance with the 18 present invention for forming a membrane silicon nozzle with 19 an offset exit aperture;
FIG. 9 is a cross-sectional view of a tapered nozzle 21 formed in a silicon wafer of (100) crystal orientation, where-22 in the wafer normal is aligned with respect to the (100) crystal 23 axis;
Z4 FIG. 10 is a cross-sectional view of a tapered nozzle forme~ in a silicon wafer of (100) crystal orientation, where-26 in tha wafer normal is misaligned with respect to the (100) 27 crystal axis;
28 ~IG. ll illustrates a tapered nozzle array formed in.
~073959 1 a sllicon wafer of (100) crystal orlentation, whereln the 2 wafer normal ls misaligned with respect to the (100) crystal 3 axis, and which illustrates fluid flow from the array;
4 FIGS. 12A-12H represent sequential cross-sectional
9 The use of laterally staggered multiple arrays as set forth in U.S. Reissue Patent RE. 28,219 to Taylor et al.
11 provides an alternative to fabricating nozzles on close 12 centers, while introducing at least two problems.
13 The first problem is that additional timing networks 14 are utilized to permit the staggered array of RE. 28,219 to effectively emulate one line of nozzles. That is, for a 16 staggered array of two rows of nozzles, for example, the print 17 signal applied to the upper row of nozzles must be delayed or 18 advanced with respect to the print signal applied to the lower 19 row of nozzles dependent upon the direction of travel of the printing medium, such that the droplets from the two rows of 21 nozzles are sequentially applied a row at a time to form a 22 single line on the printing medium.
23 The second problem deals with the gutter structure 24 and required deflection voltages. If a single gutter is used, then non-printing droplets from both rows of nozzles must be 26 deflected to the single gutter. This requires a higher def-27 lection voltage than is used for a single row of nozzles due 28 to the different and substantially parallel droplet trajector-. . .
. . .
~073~59 1 ies from the two rows. Two gutters may be used as in Taylor et al, but this results in a more complex physical 3 structure for the printer.
4 According to the present invention an ink jet printer including a staggered nozzle array is disclosed, in 6 which the a~ove-named problems are eliminated or at least 7 substantially reduced. This is accomplished by having the 8 droplet streams from at least one of the rows emanate off-g normal with respect to the plane of the nozzle plate, result-ing in the droplets from the respective rows concurrently 11 converging in non-parallel tra~ectories to form a single line 12 at a given time on the printing medium. Accordingly, the need 13 for complex timing circuitry to achieve line at a time printing 14 from a staggered nozzle array i9 substantially reduced. Thi5 is so, since all of the dot positions of a line which i9 to be 16 printed, are printed concurrently by the ~ets emanating from 17 the respective rows of nozzles, rather than sequentially, that 18 i9 by a row of nozzles at a time, as disclosed by Taylor et al.
19 Further, since the gutter is rel-atively close to the printing medium, the upper set of droplet streams require only 21 slightly more deflection than the lower set of droplet streams 22 in order to gutter the respective droplets. This is so, since 23 the respective droplet streams are converging towards the 24 respective dot positions of the line as they approach the printing medium. Therefore, a deflection voltage may be used 26 for the respective droplet streams which is essentially the 27 same as would be used for a slngle row of streams, since each 28 droplet stream is substantially the same distance from the gutter ns they near the printing medlum, resulting in the 2 droplets from the respective streams striking the gutter 3 relatively close to one another.
.
~ 4 Summary of The Invention According to the present invention a jet printer 6 is disclosed which includes a nozzle pl-ate comprised of a 7 semiconductor substrate having at least two rows of nozzles 8 formed therein> with the nozzles in one row being laterally 9 staggered with respect to the nozzles ln another row. Each nozzle has entrance and exit apertures of different cross-11 sectional area, with the exit aperture of each of the nozzles 12 in at least one row belng axially misaligned with respect to 13 the longitudlnal center axis of their respective entrance 14 apertures. A method of printing at least a portion of a line at a time on a printing medium is accomplished, wherein the 16 line is comprised of a plurality of dot posltions. The jets 17 from one row of nozzles are directed towards a selected first 18 group of non-adjacent dot positions of said line on the print-19 ing medium, and concurrent therewith the jets from another row of nozzles are directed in a non-parallel trajectory with 21 respect to the trajectory of the jets from the one row of 22 nozzles, towards a selected second group of non-adjacent dot 23 positions of the line on sald prlnting medium.
24 Brief Description of the DrawinRs 25 - FIG. 1 i8 a sectional side view of a staggered 26 nozzle arra-y for printing a line at a time according to the 27 present invention;
1 FIG. 2 18 a perspectlve v$ew oL a staggercd nozzle 2 array according to the present invention;
3 FIG. 3 is a front view of a charge electrode 4 structure uhich may be utilized in the practice of the present inventlon; -6 FIG. 4 is a back to front view of a membrane silicon 7 nozzle;
8 FIGS. 5 and 6 are cross-sectional views illustrating 9 fluid 10w in normal and reverse directions, respectively, through a tapered nozzle;
11 FIG. 7 is a cross-sectional view of a membrane 12 silicon nozzle in which the exit aperture of the nozzle is 13 offset with respect to the longitudinal center axis of the .14 entrance aperture of the nozzle, and which illustrates fluid flow from the nozzle;
16 FIGS. 8A-8J represent sequential cross-sectional 17 views of a silicon wafer processed in accordance with the 18 present invention for forming a membrane silicon nozzle with 19 an offset exit aperture;
FIG. 9 is a cross-sectional view of a tapered nozzle 21 formed in a silicon wafer of (100) crystal orientation, where-22 in the wafer normal is aligned with respect to the (100) crystal 23 axis;
Z4 FIG. 10 is a cross-sectional view of a tapered nozzle forme~ in a silicon wafer of (100) crystal orientation, where-26 in tha wafer normal is misaligned with respect to the (100) 27 crystal axis;
28 ~IG. ll illustrates a tapered nozzle array formed in.
~073959 1 a sllicon wafer of (100) crystal orlentation, whereln the 2 wafer normal ls misaligned with respect to the (100) crystal 3 axis, and which illustrates fluid flow from the array;
4 FIGS. 12A-12H represent sequential cross-sectional
- 5 views of a silicon wafer which is misaligned with respect to
6 the (100) crystal axls, and which is processed in accordance
7 with the present invention; . -
8 FIG. 13 is a cross-sectional view of an ink ~et
9 printing system including a staggered jet nozzle array in accordance with the present invention;
11 FIG. 14 is a front view of a membrane nozzle having 12 a circular exit aperture whlch is offset from the center of 13 the membrane;
14 FIG. 15 is a graph of deflection angles versus 15. orifice misregistration for a membrane-type nozzle;
16 FIG. 16 is a pictorial representation of an 17 off-normal droplet tra~ectory towards a gutter;
18 FIG. 17 is a pictorial representation of a normal 19 droplet trajectory towards a gutter;
FIG. 18 is a plctorlal representatlon of the 21 off-normal droplet tra~ectories for two droplet streams 22 towards a gutter;
23 FIG. 19 19 a plctorial representation of a plurality 24 of droplet streams emanating from a staggered nozzle array according to the present invention;
26 FIGS. 20A-20D are timlng diagrams which lllustrate 27 the times at which charging voltages are applied to the drop-28 lets emanating from the respective rows of nozzles in the 29 nozzle array of FIG. 19; and , . , ,, . ... . ~
~0739~9 1 . FIG. 21 is a pictorial view of an ink jet printing 2 system including a nozzle array which includes guard jets on 3 the perimeter of the array for minimizing the aerodynamic 4 retardation felt by the jets emanating from the nozzles on the interior of the array.
6 Detailed Description of The Invention 7 According to the present invention, a method of 8 printing a portion of a line at a time, a line at a time, or g ~everal lines at a time from a ~et nozzle array is disclosed.
The ~et nozzle array may be fabricated in a semiconductor 11 material using ^onventlonal semiconductor processing techniques.
12 The preferred material is semiconductor silicon, however, it is 13 to be appreciated that other semiconductor materials such as 14 germanium, gallium arsenide, or the like, may be utilized in the practice of the present invention. Also, it is to be 16 appreciated tkat materials other than semiconductors may be 17 used in the practice of the present invention. The processing 18 technique used in the preferred embodiment, that is for 19 silicon, utilizes an anisotropic chemical etchant for genera-ting holes of desired geometries in the semiconductor material.
21 The preferred geometry is that the hole is tapered from 22 entrance to exit aperture.
23 In one embodiment the hole has a polygonal entrance 24 aperture which tapers to a polygonal exit aperture. In practice, the corners of the apertures may be rounded off to 26 minimize stress concentrations which may result in failure or 27 excessive wear of a nozzle. In another embodiment the hole 28 is ln the shape of a truncated pyramid having a rectangular 29 entrance aperture which tapers to a rectangular cross-sectional ~073~359 1 area in which is formed a membrane having a circular oriflce 2 formed there~n.
3 The excellent performance characteristics of the 4 pFesent nozzle array is directly related to the influence of crystal symmetry on the geometry of the nozzle which results 6 ln the nozzle having predictable directional and velocity 7 characteristlcs and hlgh nozzle efficiency.
8 As is known, anisotropic etchants attack crystalline g materials at different rates in different crystallographic directions. Numerous anisotropic etchants are ~nown for mono-ll crystalline sllicon which include alkaline liquids or mixtures 12 thereof. As common single crystal silicon anisotropic etchants, 13 there may be mentioned aqueous sodium hydroxide, aqueous 4 potassium hydroxide, aqueous hydrazine tetramethyl, ammonium lS hydroxide, mixtures of phenols and amine5 such as a mixture of 16 pyrochatechol and ethylene diamine wlth water, and mixtures of 17 potassium hydroxide, n-propanol and water. These and other lB preferential etchants for monocrystalline silicon are usable in 19 the process of the present invention for forming jet nozzle arrays.
21 With respect to the three most common low index 22 crystal planes ln monocrystalline 5ilicon, the anisotropic etch 23 rate ls greatest for (100) oriented silicon, somewhat less for 24 (110) and is least for (111) oriented silicon. How the above-mentloned slllcon processing techniques are utilized to form 26 the nozzle arrays of the present invention are to be described 27 short]y.
28 FIG. 1 illustrates a silicon nozzle array 2 in which 29 the nozzles in one row are laterally staggered with respect to ~ 8 -, . . .
1 the nozzles ln another row. That is, the nozzle orifices 2 in one row are mutually offset with respect to the orifices 3 in another row in a direction normal to the plane of FIG. 1.
4 A;so, the nozzles in certaln rows have their exit apertures axially misaligned with respect to the longitudinal center 6 axis of their respective entrance apertures, resulting in a 7 non-normal jet trajectory with respect to the plane of the 8 nozzle plate. It is seen that tlle jet trajectory 10 from the 9 nozzle 8 is substantially normal to the plane of the nozzle plate 2, such that the jet 10 strikes a predetermined dot 11 position in a row 12, normal to the plane of the figure, on 12 a printlng medium, such as a paper 14. Accordingly, if the 13 ~et emanating from nozzles 4 and 6 are to strike other dot 14 positiohs in the row 12, the jet trajectories from nozzles 4 and 6 must be non-normal with respect to the plane of nozzle 16 plate 2 and must have a non-parallel tra~ectory with respect 17 to the jet trajectory 10. Thus, the amount sf axial offset of 18 the respective exit apertures of the nozzles in rows 4 and 6 19 are predetermined such that the jet trajectories 16 and 18 therefrom strike dot positions on the row 12 such that a line 21 at a time is printed.
22 FIG. 2 is a perspective view of the nozzle plate 2 which 23 more clearly illustrates how the jets emanating from the rows 24 4, 6 and 8 are able to produce adjacent dots for forming the line 12 nr. the paper 14. That is, the jets emanating from 26 row 4 mark non-adjacent dot positions 1, 4 and 7; the jets 27 emanating from row 6 mark non-adjacent dot positions 2, 5 28 and 8; and the jets emanating from row 8 mark non-adjacènt _ 9 1~73~59 dot positions 3, 6 and 9.
FIG. 3 illustrates a charge electrode structure 20 which may be utilized in the practice of the present invention.
The charge electrode structure 20 may be comprised of a sub-trate such as a ceramic material with a plurality of slots 22 formed therein, with the slots being machined such that they may accommodate the passage of droplet streams at different trajectories and from different rows. That is, the dimensions of the slot should be such that it may be able to pass a jet from either the first, second or third row. As is known in the art, the interior of the slots are plated with a conductive coating such that voltage may be applied to the respective slots such that droplets passing therethrough may be selectively charged, such that unchanged droplets are used for printing and charged droplets are deflected into a common gutter. The relationship of the charge electrode structure to a complete ink jet printing system is seen in more detail in FIG. 13.
As was previously stated, the nozzle array may include a plurality of nozzles formed in a silicon substrate, in which the holes forming the nozzle are in the shape of a truncated pyramid with the larger aperture forming an entrance aperture and the smaller rectangular portion thereof having a membrane formed therein with a circular orifice in the membrane which acts as the exit aperture. Such a nozzle is described in the referenced U.S. Patent No. 4,007,464, and is shown in FIG. 4, wherein a silicon wafer 24 has a hole etched therein which has an entrance aperture comprised of sides 26, 28, ~ .
.
~ ' '. . ~ . ' 1 30 and 32, and which tapers to a smaller rectangular portion 2 comprised of sides 34, 36, 38 and 40, with a membrane 42 3 formed therein, and with a circular orifice 44 formed in the 4 membrane. In such a nozzle structure, with the orifice 44 centered in the membrane 42, a jet emanating from the 6 orifice 44 is substantially normal to the plane of the mem-7 brane 42. If the orifice 44 is off-center, the jet issuing 8 from the orifice is at a non-normal angle with respect to 9 the plane of the membrane 42. How such a nozzle is fabri-cated and how one determines the amount off-center the 11 orifice should be for producing a predetermined off-normal 12 jet trajectory is described shortly.
13 Refer now to FIGS. 5 and 6. FIG. 5 illustrates 14 fluid flow in a normal direction through a tapered no.zle formed in a silicon wafer 45, that is, fluid flows from the 16 larger aperture 46 to the smaller aperture 48. Conversely, 17 FIG. 6 illustrates fluid flow in the reverse direction, that 18 is, from the smaller aperture 48 to the larger aperture 46.
19 Fluid flow through the nozzle in the forward direction as illustrated in FIG. 5 is characterized by uniform converg-21 ence of flow to the orifice 48 with velocity components 22 illustrated by arrows 50 and 52, respectively. Fluid flow 23 in the reverse direction as illustrated in FIG. 6 is charac-24 terized by a sharp change in direction of flow near the orifice 48 with velocity components illustrated by arrows 54 26 and 56. The velocity of flow in the forward direction, Vf 27 is greater than the velocity flow in the reverse direction, 28 Vr. As pressure increases, the difference between Vf and 29 Vr decreases.
1 FIG. 7 illustrates a membrane silicon nozzle formed 2 in a silicon wafer 58 which has an entrance aperture 60 and 3 an exit aperture 62 formed in a membrane 64, with the aperture 4 62 having a center line 66 which is displaced from the center - 5 axls 68 of the membrane by an amount ~. Fluid flow along a 6 wall 70, as indicated by an arrow 72, is similar to the-fluid - 7 flow in a forward direction through a nozzle as illustrated 8 in PIG. 5, wnereas fluid flow along the surface 74 of the 9 membrane 64, as indicated by an arrow 76, is similar to fluid flow in a reverse directlon through a nozzle as illustrated in 11 FIG. 6. Accordingly, fluid velocity in the direction as in-12 dlcated by the arrow 72 is greater than the fluid velocity 13 in the direction, as indicated by the arrow 76, such that 14 the ~et 78 emanatin8 from the orifice 62 is at an an~le ~
with respec. to the wafer normal 80, which in this instance 16 coincides wlth the center line 66. The amount of center axis 17 displacement o which results in a given off-normal angular 18 deflection ~ is described shortly.
19 FIGS. 8A-J illustrate one exemplary sequence of processing steps for forming 8 single ~et nozzle or an array 21 of ~et nozzles according to the present invention. As shown 22 in FIG. 8A, a silicon wafer 82 having a standard chemically-23 mechanically polished surface of p- or n-type having (100) 24 orientation is first cleaned. ~hen, as shown in FIG. 8B, the ~ilicon wafer 82 is oxidized in steam at l,000C to form an 26 SiO2 film 84 ~ 4500A thick on the front and back of the wafer, 27 with a layer of membrane material 86, for example pyrex, being 28 deposited on the front SiO2 layer 84. Next, as shown in ~IC.
29 8C, the wafer is then coated with a photoresist material 88 -~07395~
- 1 on the front and back thereof. Then, as shown in FIG. 8D, a 2 nozzle base hole pattern 90 is exposed and developed in the 3 back photoresist layer 88. Next, as illustrated in FIG. 8E, 4 the SiO2 layer in the opening 90 is etched away in a buffered hydrofluoric acid, to the back surface 92 of the wafer 82.
6 As shown in FIG. 8F, the silicon is then etched from the open-? ing 90 in an anisotropic etchant, for example, a solution 8 containing ethylene diamine, pyrochatecol and water, at 9 110-120C to form a tapered opening in the wafer. The tapered opening is defined by walls 94 and 96. The etching period is 11 generally or. the order of 3-4 hours for a substrate on the 12 order of 8 mils thick. Next, as shown in FIG. 8G, à hole 13 pattern 97 is exposed and developed in the front photoresist 14 layer 88, with the orifice pattern being offset from the center axls 98 to an axis 100 by a distance ~. Then, as illustrated in 16 FIG. 8H, the membrane layer 86 is etched to a front surface 17 102 of the 8iO2 layer 84. Next, as illustrated in FIG. 8I, 18 the SiO2 layer 84 directly under the orifice pattern 102 is 19 etched away leaving an exit orifice 104. Finally, as illus-trated in FIG. 8J, the photoresist layer 88 is removed from 21 the front and back of the wafer, and the nozzle may then be 22 oxidized to prevent corrosion or the like.
23 FlG. 9A illustrates a silicon wafer 106 of (100) 24 crystal orientation, wherein the wafer normal 108 is aligned with respect to the (100) crystal axis 110, which is indicated 26 within the wafer 106 by dots 112. The wafer 106 has an opening 27 etched therein in the shape of a truncated pyramid having a 28 polygonol entrance aperture 114 which tapers to a smaller 29 polygonol exit aperture 116, such that fluid flow from the l entrance aperture 114 to the aperture 116 is substantially 2 normal to the wafer face. FIG. 9B is an end view of the 3 orifice 116. Fluid emitted from the orifice 116 is rectang-4 ular in cross-section immediately as it exits, however, due to the surface tension of the fluid, the cross-section of the 6 Jet stream soon becomes circular.
- 7 Refer now to FIG. lOA which illustrates a silicon 8 wafer 118 of (100) crystal orientation, wherein the wafer 9 normal 120 is misaligned wlth respect to the (100) crystal axis 122 by an angular amount ~. The crystal orientation is 11 schematically illustrated by the dots 124 within the wafer 12 118. Etchant is applied to the surface 126 of the wafer, 13 in the area which is defined in part by the points 128 and 14 130. This area defines a large aperture 131. The wafer etches faste~t along a wall 129 and slo~er along a wall 132, 16 due to the crystallographic orientation of the wafer, result-17 ing in a smaller aperture 134 which is misaligned or off-center 18 with respect to the longitudinal center axis 120 of the larger 19 aperture 131. ~IG. lOB as an end view of the smaller aperture 134, is seen to be polygonol and non-rectangular in shape.
21 Also, it is seen that the smaller orifice 134 is misaligned 22 or off-center, with respect to the longitudinal center axis of 23 the larger aperture 131. In this instance the longitudinal 24 center axis of the larger aperture is identical with the line 120 which designates the wafer normal. If fluid is made to 26 flow from the larger aperture 131 to the smaller aperture 134, 27 the jet issues 'rom the orifice 134 at an angle with respect 28 to the wafer normal.
107395g 1 FIG. 11 illustrates a silicon wafer 136 of (100) 2 crystal orientation, wherein the wafer normal 138 is mis-3 aligned by an angular amount O with respect to the (100) 4 crystal axis 140. An opening 142 is formed in the wafer by etching from the front face 144 to the back face 146.
6 Another opening 148 is formed by etching in the reverse 7 direction, that is, from the back face 146 to the front face 8 144. If fluid, from a source (not shown), is in contact 9 with the face 146, fluid flow through the opening 142 is similar to that from a classical orifice, since the fluid 11 does not touch the walls of the opening and the jet trajec-12 tory is essentially normal to the front face 144 of the 13 wafer. On the other hand, since the fluid flow through the 14 opening 148 is in contact with the walls of the opening, the jet emanating from the opening is at a ncn-normal traiectory 16 with respect to the front face 144 of the wafer 136. As 17 previously described, the use of non-parallel jet trajector-18 ies may be used to print a line at a time on a printing 19 medium. How openings are etched to form a nozzle array as illustrated in FIG. 11 is set forth in the description which 21 follows for FIG. 12.
22 FIGS. 12A-12H illustrate one exemplary sequence of 23 processing steps to produce apertures or holes in a single 24 crystal silicon wafer for forming a jet nozzle array. It is to be appreciated that the following process steps may be 26 used in a different sequence. Also, other film materials 27 for performing the same function below may also be used.
28 Further, film formation, size, thickness and the like may be 29 varied.
The fabrication steps for forming an array of jet 1073959~
1 nozzles according to the present invention may be carried out 2 in the following se~uence on a silicon wafer, where the wafer 3 nbrmal is misaligned with respect to the (100) crystal axis 4 as set forth in relation to FIGS. 10 and 11. As shown in _ 5 FIG. 12A, a misaligned silicon wafer 154 which has standard 6 chemically-mechanically polished surfaces of p- or n-type, and 7 of (100) orientation is first cleaned. Then, as shown in 8 FIG. 12B, the silicon wafer 154 is oxidi~ed in steam at 9 1,000C to form an SiO2 film 156 ~ 4500A thick on the front and back of the wafer. Next, as shown in FIC. 12C, the oxi-11 dized wafer is then coated with a photoresist material 158 on 12 the front and back of the wafer. Then, as shown in FIG. 12D, 13 a noz~le base hole pattern 160 is exposed and developed in the 14 photoresist layer 158 on the front side, and a nozzle base hole pattern 162 is exposed and developed in the photoresist layer 16 158 on the back of the wafer. Next, as illustrated in FIG. 12E, 17 the SiO2 layer in the openings 160 and 162 are etched away in 18 buffered hydrofluoric acid, and then the photoresist 158 is 19 stripped frcm both sides of the wafer. As shown in FIG. 12F, the silicon is then etched from the openings 160 and 162 in 21 an anisotropic etchant, for example, a solution containing 22 ethylene diamine, pyrochatecol and water, at 110-120C to form 23 the tapered openings 164 and 166, respectively, in the wafer 24 154. Etching is stopped when orifices appear on the opposite side of the wafer from where the etching started. The etching 26 period is generally on the order of 3-4 hours for a substrate 27 on the order of 8 mils thick. As shown in FIG. 12G, tlle SiO2 28 layer 156 is etched from the wafer 154 resulting in a silicon 29 wafer with openings 164 and 166 appearing thcrein. The wafer .
] 154 t~hen ha.s an SiO2 film 168 gr~wn thereon by oxidation as 2 illustrated in FIG. 1271. The oxide layer 168 helps to prevent 3 corrosion by the inks used in the ink jet printer. It is to 4 be appreciated that other corrosion-resistant films may be used.
FIG. 13 illustrates generally at 170 an ink jet 6 printing system in cross-section which utilizes a nozzle array 7 fabricated in accordance with the present invention. A nozzle 8 plate 172 is fabricated in a silicon wafer with two rows of 9 nozzles 174 and 176 which are laterally staggered with respect to the plane of the drawing. The center-to-center distance 11 from the nozzles in one row to another row is on the order of 12 .016 inches as illustrated. The nozzles in row 174 are fab-13 ricated such that a jet emanating therefrom is at an angle of 14 approximately 1 downward with respect to the normal of the exit plane of the nozzle. The nozzles in row 176 are fabricated 16 such that a jet emanating therefrom is at an upward angle of 17 approximately 1 with respect to the normal of the exit plane 18 of the nozzle. For such a nozzle array the individual nozzles 19 are membrane nozzles fabricated in accordance with the technique set forth in FIGS. 8A-8J. ~lso, more than two rows of nozzles 21 could be used, but for ease of illustration only two sets of 22 rows are shown Also, the nozzles could all be pointing at 23 a downward angle, or all pointing at an upward angle. Alter-24 natively, one row of nozzles could emit ~ets at a normal angle while all others are emitting jets at a non-parallel traject-26 ory with respect to the normal jet trajectory. Also, nozzles 27 with polygonol exit apertures which are fabricated in accordance -28 with the techniques set forth in FIC. 12 could be utilized in 29 the array in place of the membrane nozzles. In such an l one row Or Jets would be normal to t~le pl3ne Or tllc ;Ir~-ly and 2 the ~ets from the other row would be in a non-normal traject-3 dry.
4 ~ A charge electrode structure 178 having a side dimension of 0.06 inch $s spaced on the order of 0.02 inch 6 from the nozzle plate. The charge electrode structure, for 7 example, may be as lllustrated in FIG. 3. A deflection and 8 gutter assembly having a side dimension of 0.3 inch and shown g generally at 180 ls spaced on the order of 0.05 inch from the charge electrode structure 178. A high voltage deflection 11 plate 182 is connected to a high voltage source (not shown).
12 The high voltage used is on the order of 1-2 KV. A 1QW voltage 13 electrode 184 is connected to ground. The low voltage 14 electrode '84 may be made of a porous material and function also as a gutter with a pipe 186 being connected to a vacuum 16 source and an ink supply (not shown) for drawing the guttered 17 ink through the porous material and the pipe 186 for return ~ ~ -18 to the supply. As was stated earlier, the use of non-parallel 19 ~et trajectories results in guttered droplet streams striking the deflec~ion plate and gutter assembly at substantially 21 the same pointj while not having to utilize an excessively 22 high vol~age due to the different tra~ectories. A printing 23 medium 188 is spaced on the order of 0.07 inch from the 24 deflection and gutter assembly 180 and the non-guttered drop-lets from the rows 174 and 176 form alternate dot positions 26 of a single line at a tlme on the printing medium. The paper 27 i88 may be sequentially moved in the direction of an arrow 28 190 after each row is printed.
10739s9 1 Refer now to FIG. 14 which illustrates a mem-2 brane nozzle having an off-center orifice axis which results 3 ;n a 1 angle trajectcry of a jet relative to the normal of 4 the plane of the membrane, and to FIG. 15 which is a plural-ity of curves which are used to determine the deflection 6 angle dependent upon the amount the orifice is off-center 7 as well as the size of the orifice. In FIG. 14, the mem-8 brane portion 192 of a membrane silicon nozzle fabricated g in accordance with FIG. 8 is illustrated, wherein the exit orifice 194 has its center axis 196 displaced a distance S
11 from the center axis 198 of the membrane. The curves 200, 12 202, 204, 206 and 208 of FIG. 15 represent different nozzle-13 to-membrane ratios for a given pressure.
14 The equations used for determining the angle of deflection relative to the normal of the plane of the array -16 from FIG. 15 are as follows:
17 Nozzle-to-membrane ratio = d D
18 Orifice misregistration (%) = S x 100 19 for the dimensions where:
D is the side dimension of the square membraneg 21 d is the diameter of the orifice in the membrane;
22 a = D
23 S is the distance from the center axis of the 24 membrane to the center axis of the orifice.
For the dimensions shown on FIG. 14:
26 Nozzle-to-membrane ratio = d = 1 - 0.26; and D 3.85 27 Orifice misregistration (%) = ~ x 100 = 90 y 47%
a 1.925 28 For a nozzle-to-membrane ratio of approximately 0.26, 1 the curve 206 of FIG. 15 is utilized to determine the off-normal 2 jet angle. As set forth above, the orifice misregistration is 3 approximately 47%, therefore, the point 210 on the curve 206 4 of FIG. 15 is determinative of the off-normal jet angle for ~ 5 the membrane nozzle of FIG. 14. It is seen from FIG. 15 that 6 the off-normal jet angle is approximately 1. For the orienta-7 tion shown, that is, the orlfice formed above the membrane 8 center axis, the ~et would emanate at a downward angle. On 9 the other hand if the orifice is formed below the center axis of the membrane, the Jet would emanate at an upward angle.
11 For the graph shown, deflection angles approaching 4 are 12 readily obtainable.
13 As was previously stated, the present invention 14 allows for a single gutter and deflection assembly in which standard deflection voltages may be used, and wherein the 16 guttered droplets from the respective rows of the array are 17 guttered i~ substantially the same position in the gutter.
18 This is more readily seen with respect to FIGS. 16, 17 and 18.
19 FIG. 16 illustrates a deflection system including a high voltage deflection plate 212, a low voltage deflection plate 21 2i4 and a gutter 216. A droplet stream 218 has a veloclty Vd 22 at an angle 0 with respect to the normal of the plane of the 23 nozzle array, with the droplets at a point 220 being displaced 24 an amount from the central longitudlnal axis 221 between the deflection plates. The following parameters and equations 26 define the trajectory of guttered droplets for a system as set 27 forth in FIG. 16, where:
~073959 .
1 Vd = droplet velocity;
2 V = deflection Yoltage;
3 ' S = plate separation;
4 Qd = charge on drops;
_ 5 md = mass of dropR;
6 a = acceleratlon; and 7 E = distance of droplet from x axis when entering 8 deflectlon plate.
9 (1) VOx = Vd C09~ tinitial velocity along x axis) (2) VOY = Vd sin~ (initial velocity alon~ y axis) 11 (3) F mda S Qd a S Qd (force on a droplet) md 12 (4) x = Voxt ~ (Vd cos~)t 13 (5) y - yO + Voyt + 21 at 14 (6) y ~ -~ + Vd sin~ t + 1 at2 (7) y = -E + Vd sin~ x + 1 a x Vd cos~ d cos ~ -16 For dropR on lower ~et (aimed upward, displaced E downward):
17 (8) YL = - E + tan~ x + 1 a d c~s ~
18 For drops on upper jet (not shown) aimed downward, displaced 19 E upward:
(9) YU = E - tan~ x + 1 a x2 d cos a 21 FIG. 17 illustrates a normal jet trajectory relative 22 to the plane of the noz~le plate which is guttered in the 23 gutter 216. The following equàtions describe the y jet 24 trajectory in such an instance.
1073~59 1 (10) y = 1 a x2 (gutten condition: x = L, S =
2 Vd2 2 ~ /2) With all variables (velocity, voltages, etc.) held 3 fixed, the trajectory of the upper and lower drop streams as 4 described by equations (8) and (9) will merge in approx-imately the same place as the drop stream as described by 6 equation (10) if ~ = L tanO since at x = L
7 (11 ) Y~ = YU = 1 a ~ ~ S
8 since:
9 (12) cos20 ~ 1 ~2 = 1- ( 1 )2 = 0 9997 (f O
FIG. 18 illustrates the jet trajectories from two 11 rows of nozzles when the jets 224 from the upper row are 12 deflected at a downward angle 0 relative to the normal of 13 the nozzle plate, and the lower row of jets 226 are directed 14 at an upward angle 9 with respect to the normal of th~
nozzle plate. It is to be appreciated that this is one of 16 the worst case conditions for non-parallel jet trajectories 17 from respective rows of nozzles to be guttered in a single 18 gutter. For a deflection plate having a length of 0.3 19 inches and an angle 6 of 1, then = O . 3 which - 0.005 57.3 inches. These are the dimensions set forth for the ink jet 21 printing system in FIG. 13, and it is seen that with these 22 dimensions the jets 224 and 226 will strike the gutter in 23 approximately the same position with the same deflection 24 voltage applied to both jets.
FIG. 19 illustrates a nozzle plate 228 having 26 laterally staggered rows of nozzles 230, 232, 234 and 236, 27 with the jets 238 and 240 from the rows 230 and 232, re-28 spectively, being directed at a downward angle towards a 29 printing medium ~073959 1 242, and wLtl- ~ets 244 and 246 from rows 234 and 236, respect-2 lvely, belng dlrected at an upward angle towards the printing 3 medium 2/~2. It ls seen that the distance the drops emanating 4 from rows 232 and 234 have to travel are substantially the same, and that the distance the drops from the rows 230 and 236 6 have to travel are also substantially the same. Further, it 7 is seen that the distance the drops from the rows 230 and 236 8 have to travel is farther than the distance the drops from the 9 rows 232 and 234 have to travel. Accordingly, drops emanating from the rows 230 and 236 must have a print signal applied to 11 them at a time ~ earlier than print signals which are applied 12 to the droplets emanating from rows 232 and 234. In other words 13 the drops emanating from the rows 232 and 234 have print signals 14 applied to them which are delayed relative to the print signals for rows 230 and 236. This is seen more clearly in relation 16 to FIG. 20, wherein FIG. 20A and FIG. 20D are the print signals 17 applied to drops emanating from rows 230 and 236, respect-18 ively, whereas the print signals illustrated in FIGS. 20B and 19 20C are the print signals applied to drops emanating from rows 232 and 234. Since the print signals applied to drops 21 from rows 230 and 236 occur at the same time, they may be 22 driven from a common timing source. The print signals applied 23 to drops from rows 232 and 234 may be driven .from another 24 common driving source. Accordingly, for a system as illus-trate~ in FIC. 19 the timing and delay networks utilized may 26 be reduced by a factor of 2 relative to known laterally stagger-27 ed printing systems which have a different timing sequence for 28 each row. It is to be appreciated, however, that the actual :~ 10739S9 1 psth length differences are typlcally very small and that for 2 many printing applications delay networks may be unnecessary.
3 For example~ wlth reference to FIG. 19, if the distance between 4 ad~acent rows are each 0.016" and the distance between nozzle , plate 228 and printing medium 242 i9 0.5", the maximum path 6 length difference for drop streams is about 0.0005". For 7 many printing applications, the drop placement error caused 8 by this path length difference is negligibly small, so that 9 delay networks would not be needed which greatly simplifies the circuitry.
11 As set forth in the previously referenced patent 12 application Serial No. 591,984 of Hendriks, guard jets may 13 be utilized to prevent aerodynamic retardation of droplet 14 streams which are to be used for printing. That is, droplet streams on tlle perimeter of an àrray are continuously guttered 16 to set up an air flow which prevents aerodynamic retardation 17 of droplet streams emitted from nozzles on the interior of the 18 array. In ~IG. 21, a nozzle array 248 includes a plurality 19 of membrane-type nozzles in which nozzles 250 and 252 on the perimeter of thP array have their respective orifices 254 and 21 256 offset in an upward direction with respect to the orifices 22 of the remaining nozzles 258, 260 and 262. Also, the orifices 23 254 and 256 may be made larger than the orifices of the other 24 nozzles such that the emitted droplets are larger and create a greater air flow. Charging and deflection electrodes are 26 not shown for clarity of the drawing. For the system shown, 27 the droplet streams emanating from the nozzles 250 and 252 are 28 at a downward angle with respect to the normal of the plane of 2g the nozzle plate and are aimed at a gutter 264 such that the droplets from the nozzle 250 and 252 are continuously guttered 1 and require no charging and/or deflection voltages. The drop-2 let streams emanating from the interior of the array, namely 3 from the nozzles 258 and 260 and 262 are selectively charged 4 and accordingly guttered in accordance with standard ink jet printing practices while not requiring complex electronic 6 circuitry to compensate for the normal aerodynamic drag of 7 printing droplets on the exterior of the array.
11 FIG. 14 is a front view of a membrane nozzle having 12 a circular exit aperture whlch is offset from the center of 13 the membrane;
14 FIG. 15 is a graph of deflection angles versus 15. orifice misregistration for a membrane-type nozzle;
16 FIG. 16 is a pictorial representation of an 17 off-normal droplet tra~ectory towards a gutter;
18 FIG. 17 is a pictorial representation of a normal 19 droplet trajectory towards a gutter;
FIG. 18 is a plctorlal representatlon of the 21 off-normal droplet tra~ectories for two droplet streams 22 towards a gutter;
23 FIG. 19 19 a plctorial representation of a plurality 24 of droplet streams emanating from a staggered nozzle array according to the present invention;
26 FIGS. 20A-20D are timlng diagrams which lllustrate 27 the times at which charging voltages are applied to the drop-28 lets emanating from the respective rows of nozzles in the 29 nozzle array of FIG. 19; and , . , ,, . ... . ~
~0739~9 1 . FIG. 21 is a pictorial view of an ink jet printing 2 system including a nozzle array which includes guard jets on 3 the perimeter of the array for minimizing the aerodynamic 4 retardation felt by the jets emanating from the nozzles on the interior of the array.
6 Detailed Description of The Invention 7 According to the present invention, a method of 8 printing a portion of a line at a time, a line at a time, or g ~everal lines at a time from a ~et nozzle array is disclosed.
The ~et nozzle array may be fabricated in a semiconductor 11 material using ^onventlonal semiconductor processing techniques.
12 The preferred material is semiconductor silicon, however, it is 13 to be appreciated that other semiconductor materials such as 14 germanium, gallium arsenide, or the like, may be utilized in the practice of the present invention. Also, it is to be 16 appreciated tkat materials other than semiconductors may be 17 used in the practice of the present invention. The processing 18 technique used in the preferred embodiment, that is for 19 silicon, utilizes an anisotropic chemical etchant for genera-ting holes of desired geometries in the semiconductor material.
21 The preferred geometry is that the hole is tapered from 22 entrance to exit aperture.
23 In one embodiment the hole has a polygonal entrance 24 aperture which tapers to a polygonal exit aperture. In practice, the corners of the apertures may be rounded off to 26 minimize stress concentrations which may result in failure or 27 excessive wear of a nozzle. In another embodiment the hole 28 is ln the shape of a truncated pyramid having a rectangular 29 entrance aperture which tapers to a rectangular cross-sectional ~073~359 1 area in which is formed a membrane having a circular oriflce 2 formed there~n.
3 The excellent performance characteristics of the 4 pFesent nozzle array is directly related to the influence of crystal symmetry on the geometry of the nozzle which results 6 ln the nozzle having predictable directional and velocity 7 characteristlcs and hlgh nozzle efficiency.
8 As is known, anisotropic etchants attack crystalline g materials at different rates in different crystallographic directions. Numerous anisotropic etchants are ~nown for mono-ll crystalline sllicon which include alkaline liquids or mixtures 12 thereof. As common single crystal silicon anisotropic etchants, 13 there may be mentioned aqueous sodium hydroxide, aqueous 4 potassium hydroxide, aqueous hydrazine tetramethyl, ammonium lS hydroxide, mixtures of phenols and amine5 such as a mixture of 16 pyrochatechol and ethylene diamine wlth water, and mixtures of 17 potassium hydroxide, n-propanol and water. These and other lB preferential etchants for monocrystalline silicon are usable in 19 the process of the present invention for forming jet nozzle arrays.
21 With respect to the three most common low index 22 crystal planes ln monocrystalline 5ilicon, the anisotropic etch 23 rate ls greatest for (100) oriented silicon, somewhat less for 24 (110) and is least for (111) oriented silicon. How the above-mentloned slllcon processing techniques are utilized to form 26 the nozzle arrays of the present invention are to be described 27 short]y.
28 FIG. 1 illustrates a silicon nozzle array 2 in which 29 the nozzles in one row are laterally staggered with respect to ~ 8 -, . . .
1 the nozzles ln another row. That is, the nozzle orifices 2 in one row are mutually offset with respect to the orifices 3 in another row in a direction normal to the plane of FIG. 1.
4 A;so, the nozzles in certaln rows have their exit apertures axially misaligned with respect to the longitudinal center 6 axis of their respective entrance apertures, resulting in a 7 non-normal jet trajectory with respect to the plane of the 8 nozzle plate. It is seen that tlle jet trajectory 10 from the 9 nozzle 8 is substantially normal to the plane of the nozzle plate 2, such that the jet 10 strikes a predetermined dot 11 position in a row 12, normal to the plane of the figure, on 12 a printlng medium, such as a paper 14. Accordingly, if the 13 ~et emanating from nozzles 4 and 6 are to strike other dot 14 positiohs in the row 12, the jet trajectories from nozzles 4 and 6 must be non-normal with respect to the plane of nozzle 16 plate 2 and must have a non-parallel tra~ectory with respect 17 to the jet trajectory 10. Thus, the amount sf axial offset of 18 the respective exit apertures of the nozzles in rows 4 and 6 19 are predetermined such that the jet trajectories 16 and 18 therefrom strike dot positions on the row 12 such that a line 21 at a time is printed.
22 FIG. 2 is a perspective view of the nozzle plate 2 which 23 more clearly illustrates how the jets emanating from the rows 24 4, 6 and 8 are able to produce adjacent dots for forming the line 12 nr. the paper 14. That is, the jets emanating from 26 row 4 mark non-adjacent dot positions 1, 4 and 7; the jets 27 emanating from row 6 mark non-adjacent dot positions 2, 5 28 and 8; and the jets emanating from row 8 mark non-adjacènt _ 9 1~73~59 dot positions 3, 6 and 9.
FIG. 3 illustrates a charge electrode structure 20 which may be utilized in the practice of the present invention.
The charge electrode structure 20 may be comprised of a sub-trate such as a ceramic material with a plurality of slots 22 formed therein, with the slots being machined such that they may accommodate the passage of droplet streams at different trajectories and from different rows. That is, the dimensions of the slot should be such that it may be able to pass a jet from either the first, second or third row. As is known in the art, the interior of the slots are plated with a conductive coating such that voltage may be applied to the respective slots such that droplets passing therethrough may be selectively charged, such that unchanged droplets are used for printing and charged droplets are deflected into a common gutter. The relationship of the charge electrode structure to a complete ink jet printing system is seen in more detail in FIG. 13.
As was previously stated, the nozzle array may include a plurality of nozzles formed in a silicon substrate, in which the holes forming the nozzle are in the shape of a truncated pyramid with the larger aperture forming an entrance aperture and the smaller rectangular portion thereof having a membrane formed therein with a circular orifice in the membrane which acts as the exit aperture. Such a nozzle is described in the referenced U.S. Patent No. 4,007,464, and is shown in FIG. 4, wherein a silicon wafer 24 has a hole etched therein which has an entrance aperture comprised of sides 26, 28, ~ .
.
~ ' '. . ~ . ' 1 30 and 32, and which tapers to a smaller rectangular portion 2 comprised of sides 34, 36, 38 and 40, with a membrane 42 3 formed therein, and with a circular orifice 44 formed in the 4 membrane. In such a nozzle structure, with the orifice 44 centered in the membrane 42, a jet emanating from the 6 orifice 44 is substantially normal to the plane of the mem-7 brane 42. If the orifice 44 is off-center, the jet issuing 8 from the orifice is at a non-normal angle with respect to 9 the plane of the membrane 42. How such a nozzle is fabri-cated and how one determines the amount off-center the 11 orifice should be for producing a predetermined off-normal 12 jet trajectory is described shortly.
13 Refer now to FIGS. 5 and 6. FIG. 5 illustrates 14 fluid flow in a normal direction through a tapered no.zle formed in a silicon wafer 45, that is, fluid flows from the 16 larger aperture 46 to the smaller aperture 48. Conversely, 17 FIG. 6 illustrates fluid flow in the reverse direction, that 18 is, from the smaller aperture 48 to the larger aperture 46.
19 Fluid flow through the nozzle in the forward direction as illustrated in FIG. 5 is characterized by uniform converg-21 ence of flow to the orifice 48 with velocity components 22 illustrated by arrows 50 and 52, respectively. Fluid flow 23 in the reverse direction as illustrated in FIG. 6 is charac-24 terized by a sharp change in direction of flow near the orifice 48 with velocity components illustrated by arrows 54 26 and 56. The velocity of flow in the forward direction, Vf 27 is greater than the velocity flow in the reverse direction, 28 Vr. As pressure increases, the difference between Vf and 29 Vr decreases.
1 FIG. 7 illustrates a membrane silicon nozzle formed 2 in a silicon wafer 58 which has an entrance aperture 60 and 3 an exit aperture 62 formed in a membrane 64, with the aperture 4 62 having a center line 66 which is displaced from the center - 5 axls 68 of the membrane by an amount ~. Fluid flow along a 6 wall 70, as indicated by an arrow 72, is similar to the-fluid - 7 flow in a forward direction through a nozzle as illustrated 8 in PIG. 5, wnereas fluid flow along the surface 74 of the 9 membrane 64, as indicated by an arrow 76, is similar to fluid flow in a reverse directlon through a nozzle as illustrated in 11 FIG. 6. Accordingly, fluid velocity in the direction as in-12 dlcated by the arrow 72 is greater than the fluid velocity 13 in the direction, as indicated by the arrow 76, such that 14 the ~et 78 emanatin8 from the orifice 62 is at an an~le ~
with respec. to the wafer normal 80, which in this instance 16 coincides wlth the center line 66. The amount of center axis 17 displacement o which results in a given off-normal angular 18 deflection ~ is described shortly.
19 FIGS. 8A-J illustrate one exemplary sequence of processing steps for forming 8 single ~et nozzle or an array 21 of ~et nozzles according to the present invention. As shown 22 in FIG. 8A, a silicon wafer 82 having a standard chemically-23 mechanically polished surface of p- or n-type having (100) 24 orientation is first cleaned. ~hen, as shown in FIG. 8B, the ~ilicon wafer 82 is oxidized in steam at l,000C to form an 26 SiO2 film 84 ~ 4500A thick on the front and back of the wafer, 27 with a layer of membrane material 86, for example pyrex, being 28 deposited on the front SiO2 layer 84. Next, as shown in ~IC.
29 8C, the wafer is then coated with a photoresist material 88 -~07395~
- 1 on the front and back thereof. Then, as shown in FIG. 8D, a 2 nozzle base hole pattern 90 is exposed and developed in the 3 back photoresist layer 88. Next, as illustrated in FIG. 8E, 4 the SiO2 layer in the opening 90 is etched away in a buffered hydrofluoric acid, to the back surface 92 of the wafer 82.
6 As shown in FIG. 8F, the silicon is then etched from the open-? ing 90 in an anisotropic etchant, for example, a solution 8 containing ethylene diamine, pyrochatecol and water, at 9 110-120C to form a tapered opening in the wafer. The tapered opening is defined by walls 94 and 96. The etching period is 11 generally or. the order of 3-4 hours for a substrate on the 12 order of 8 mils thick. Next, as shown in FIG. 8G, à hole 13 pattern 97 is exposed and developed in the front photoresist 14 layer 88, with the orifice pattern being offset from the center axls 98 to an axis 100 by a distance ~. Then, as illustrated in 16 FIG. 8H, the membrane layer 86 is etched to a front surface 17 102 of the 8iO2 layer 84. Next, as illustrated in FIG. 8I, 18 the SiO2 layer 84 directly under the orifice pattern 102 is 19 etched away leaving an exit orifice 104. Finally, as illus-trated in FIG. 8J, the photoresist layer 88 is removed from 21 the front and back of the wafer, and the nozzle may then be 22 oxidized to prevent corrosion or the like.
23 FlG. 9A illustrates a silicon wafer 106 of (100) 24 crystal orientation, wherein the wafer normal 108 is aligned with respect to the (100) crystal axis 110, which is indicated 26 within the wafer 106 by dots 112. The wafer 106 has an opening 27 etched therein in the shape of a truncated pyramid having a 28 polygonol entrance aperture 114 which tapers to a smaller 29 polygonol exit aperture 116, such that fluid flow from the l entrance aperture 114 to the aperture 116 is substantially 2 normal to the wafer face. FIG. 9B is an end view of the 3 orifice 116. Fluid emitted from the orifice 116 is rectang-4 ular in cross-section immediately as it exits, however, due to the surface tension of the fluid, the cross-section of the 6 Jet stream soon becomes circular.
- 7 Refer now to FIG. lOA which illustrates a silicon 8 wafer 118 of (100) crystal orientation, wherein the wafer 9 normal 120 is misaligned wlth respect to the (100) crystal axis 122 by an angular amount ~. The crystal orientation is 11 schematically illustrated by the dots 124 within the wafer 12 118. Etchant is applied to the surface 126 of the wafer, 13 in the area which is defined in part by the points 128 and 14 130. This area defines a large aperture 131. The wafer etches faste~t along a wall 129 and slo~er along a wall 132, 16 due to the crystallographic orientation of the wafer, result-17 ing in a smaller aperture 134 which is misaligned or off-center 18 with respect to the longitudinal center axis 120 of the larger 19 aperture 131. ~IG. lOB as an end view of the smaller aperture 134, is seen to be polygonol and non-rectangular in shape.
21 Also, it is seen that the smaller orifice 134 is misaligned 22 or off-center, with respect to the longitudinal center axis of 23 the larger aperture 131. In this instance the longitudinal 24 center axis of the larger aperture is identical with the line 120 which designates the wafer normal. If fluid is made to 26 flow from the larger aperture 131 to the smaller aperture 134, 27 the jet issues 'rom the orifice 134 at an angle with respect 28 to the wafer normal.
107395g 1 FIG. 11 illustrates a silicon wafer 136 of (100) 2 crystal orientation, wherein the wafer normal 138 is mis-3 aligned by an angular amount O with respect to the (100) 4 crystal axis 140. An opening 142 is formed in the wafer by etching from the front face 144 to the back face 146.
6 Another opening 148 is formed by etching in the reverse 7 direction, that is, from the back face 146 to the front face 8 144. If fluid, from a source (not shown), is in contact 9 with the face 146, fluid flow through the opening 142 is similar to that from a classical orifice, since the fluid 11 does not touch the walls of the opening and the jet trajec-12 tory is essentially normal to the front face 144 of the 13 wafer. On the other hand, since the fluid flow through the 14 opening 148 is in contact with the walls of the opening, the jet emanating from the opening is at a ncn-normal traiectory 16 with respect to the front face 144 of the wafer 136. As 17 previously described, the use of non-parallel jet trajector-18 ies may be used to print a line at a time on a printing 19 medium. How openings are etched to form a nozzle array as illustrated in FIG. 11 is set forth in the description which 21 follows for FIG. 12.
22 FIGS. 12A-12H illustrate one exemplary sequence of 23 processing steps to produce apertures or holes in a single 24 crystal silicon wafer for forming a jet nozzle array. It is to be appreciated that the following process steps may be 26 used in a different sequence. Also, other film materials 27 for performing the same function below may also be used.
28 Further, film formation, size, thickness and the like may be 29 varied.
The fabrication steps for forming an array of jet 1073959~
1 nozzles according to the present invention may be carried out 2 in the following se~uence on a silicon wafer, where the wafer 3 nbrmal is misaligned with respect to the (100) crystal axis 4 as set forth in relation to FIGS. 10 and 11. As shown in _ 5 FIG. 12A, a misaligned silicon wafer 154 which has standard 6 chemically-mechanically polished surfaces of p- or n-type, and 7 of (100) orientation is first cleaned. Then, as shown in 8 FIG. 12B, the silicon wafer 154 is oxidi~ed in steam at 9 1,000C to form an SiO2 film 156 ~ 4500A thick on the front and back of the wafer. Next, as shown in FIC. 12C, the oxi-11 dized wafer is then coated with a photoresist material 158 on 12 the front and back of the wafer. Then, as shown in FIG. 12D, 13 a noz~le base hole pattern 160 is exposed and developed in the 14 photoresist layer 158 on the front side, and a nozzle base hole pattern 162 is exposed and developed in the photoresist layer 16 158 on the back of the wafer. Next, as illustrated in FIG. 12E, 17 the SiO2 layer in the openings 160 and 162 are etched away in 18 buffered hydrofluoric acid, and then the photoresist 158 is 19 stripped frcm both sides of the wafer. As shown in FIG. 12F, the silicon is then etched from the openings 160 and 162 in 21 an anisotropic etchant, for example, a solution containing 22 ethylene diamine, pyrochatecol and water, at 110-120C to form 23 the tapered openings 164 and 166, respectively, in the wafer 24 154. Etching is stopped when orifices appear on the opposite side of the wafer from where the etching started. The etching 26 period is generally on the order of 3-4 hours for a substrate 27 on the order of 8 mils thick. As shown in FIG. 12G, tlle SiO2 28 layer 156 is etched from the wafer 154 resulting in a silicon 29 wafer with openings 164 and 166 appearing thcrein. The wafer .
] 154 t~hen ha.s an SiO2 film 168 gr~wn thereon by oxidation as 2 illustrated in FIG. 1271. The oxide layer 168 helps to prevent 3 corrosion by the inks used in the ink jet printer. It is to 4 be appreciated that other corrosion-resistant films may be used.
FIG. 13 illustrates generally at 170 an ink jet 6 printing system in cross-section which utilizes a nozzle array 7 fabricated in accordance with the present invention. A nozzle 8 plate 172 is fabricated in a silicon wafer with two rows of 9 nozzles 174 and 176 which are laterally staggered with respect to the plane of the drawing. The center-to-center distance 11 from the nozzles in one row to another row is on the order of 12 .016 inches as illustrated. The nozzles in row 174 are fab-13 ricated such that a jet emanating therefrom is at an angle of 14 approximately 1 downward with respect to the normal of the exit plane of the nozzle. The nozzles in row 176 are fabricated 16 such that a jet emanating therefrom is at an upward angle of 17 approximately 1 with respect to the normal of the exit plane 18 of the nozzle. For such a nozzle array the individual nozzles 19 are membrane nozzles fabricated in accordance with the technique set forth in FIGS. 8A-8J. ~lso, more than two rows of nozzles 21 could be used, but for ease of illustration only two sets of 22 rows are shown Also, the nozzles could all be pointing at 23 a downward angle, or all pointing at an upward angle. Alter-24 natively, one row of nozzles could emit ~ets at a normal angle while all others are emitting jets at a non-parallel traject-26 ory with respect to the normal jet trajectory. Also, nozzles 27 with polygonol exit apertures which are fabricated in accordance -28 with the techniques set forth in FIC. 12 could be utilized in 29 the array in place of the membrane nozzles. In such an l one row Or Jets would be normal to t~le pl3ne Or tllc ;Ir~-ly and 2 the ~ets from the other row would be in a non-normal traject-3 dry.
4 ~ A charge electrode structure 178 having a side dimension of 0.06 inch $s spaced on the order of 0.02 inch 6 from the nozzle plate. The charge electrode structure, for 7 example, may be as lllustrated in FIG. 3. A deflection and 8 gutter assembly having a side dimension of 0.3 inch and shown g generally at 180 ls spaced on the order of 0.05 inch from the charge electrode structure 178. A high voltage deflection 11 plate 182 is connected to a high voltage source (not shown).
12 The high voltage used is on the order of 1-2 KV. A 1QW voltage 13 electrode 184 is connected to ground. The low voltage 14 electrode '84 may be made of a porous material and function also as a gutter with a pipe 186 being connected to a vacuum 16 source and an ink supply (not shown) for drawing the guttered 17 ink through the porous material and the pipe 186 for return ~ ~ -18 to the supply. As was stated earlier, the use of non-parallel 19 ~et trajectories results in guttered droplet streams striking the deflec~ion plate and gutter assembly at substantially 21 the same pointj while not having to utilize an excessively 22 high vol~age due to the different tra~ectories. A printing 23 medium 188 is spaced on the order of 0.07 inch from the 24 deflection and gutter assembly 180 and the non-guttered drop-lets from the rows 174 and 176 form alternate dot positions 26 of a single line at a tlme on the printing medium. The paper 27 i88 may be sequentially moved in the direction of an arrow 28 190 after each row is printed.
10739s9 1 Refer now to FIG. 14 which illustrates a mem-2 brane nozzle having an off-center orifice axis which results 3 ;n a 1 angle trajectcry of a jet relative to the normal of 4 the plane of the membrane, and to FIG. 15 which is a plural-ity of curves which are used to determine the deflection 6 angle dependent upon the amount the orifice is off-center 7 as well as the size of the orifice. In FIG. 14, the mem-8 brane portion 192 of a membrane silicon nozzle fabricated g in accordance with FIG. 8 is illustrated, wherein the exit orifice 194 has its center axis 196 displaced a distance S
11 from the center axis 198 of the membrane. The curves 200, 12 202, 204, 206 and 208 of FIG. 15 represent different nozzle-13 to-membrane ratios for a given pressure.
14 The equations used for determining the angle of deflection relative to the normal of the plane of the array -16 from FIG. 15 are as follows:
17 Nozzle-to-membrane ratio = d D
18 Orifice misregistration (%) = S x 100 19 for the dimensions where:
D is the side dimension of the square membraneg 21 d is the diameter of the orifice in the membrane;
22 a = D
23 S is the distance from the center axis of the 24 membrane to the center axis of the orifice.
For the dimensions shown on FIG. 14:
26 Nozzle-to-membrane ratio = d = 1 - 0.26; and D 3.85 27 Orifice misregistration (%) = ~ x 100 = 90 y 47%
a 1.925 28 For a nozzle-to-membrane ratio of approximately 0.26, 1 the curve 206 of FIG. 15 is utilized to determine the off-normal 2 jet angle. As set forth above, the orifice misregistration is 3 approximately 47%, therefore, the point 210 on the curve 206 4 of FIG. 15 is determinative of the off-normal jet angle for ~ 5 the membrane nozzle of FIG. 14. It is seen from FIG. 15 that 6 the off-normal jet angle is approximately 1. For the orienta-7 tion shown, that is, the orlfice formed above the membrane 8 center axis, the ~et would emanate at a downward angle. On 9 the other hand if the orifice is formed below the center axis of the membrane, the Jet would emanate at an upward angle.
11 For the graph shown, deflection angles approaching 4 are 12 readily obtainable.
13 As was previously stated, the present invention 14 allows for a single gutter and deflection assembly in which standard deflection voltages may be used, and wherein the 16 guttered droplets from the respective rows of the array are 17 guttered i~ substantially the same position in the gutter.
18 This is more readily seen with respect to FIGS. 16, 17 and 18.
19 FIG. 16 illustrates a deflection system including a high voltage deflection plate 212, a low voltage deflection plate 21 2i4 and a gutter 216. A droplet stream 218 has a veloclty Vd 22 at an angle 0 with respect to the normal of the plane of the 23 nozzle array, with the droplets at a point 220 being displaced 24 an amount from the central longitudlnal axis 221 between the deflection plates. The following parameters and equations 26 define the trajectory of guttered droplets for a system as set 27 forth in FIG. 16, where:
~073959 .
1 Vd = droplet velocity;
2 V = deflection Yoltage;
3 ' S = plate separation;
4 Qd = charge on drops;
_ 5 md = mass of dropR;
6 a = acceleratlon; and 7 E = distance of droplet from x axis when entering 8 deflectlon plate.
9 (1) VOx = Vd C09~ tinitial velocity along x axis) (2) VOY = Vd sin~ (initial velocity alon~ y axis) 11 (3) F mda S Qd a S Qd (force on a droplet) md 12 (4) x = Voxt ~ (Vd cos~)t 13 (5) y - yO + Voyt + 21 at 14 (6) y ~ -~ + Vd sin~ t + 1 at2 (7) y = -E + Vd sin~ x + 1 a x Vd cos~ d cos ~ -16 For dropR on lower ~et (aimed upward, displaced E downward):
17 (8) YL = - E + tan~ x + 1 a d c~s ~
18 For drops on upper jet (not shown) aimed downward, displaced 19 E upward:
(9) YU = E - tan~ x + 1 a x2 d cos a 21 FIG. 17 illustrates a normal jet trajectory relative 22 to the plane of the noz~le plate which is guttered in the 23 gutter 216. The following equàtions describe the y jet 24 trajectory in such an instance.
1073~59 1 (10) y = 1 a x2 (gutten condition: x = L, S =
2 Vd2 2 ~ /2) With all variables (velocity, voltages, etc.) held 3 fixed, the trajectory of the upper and lower drop streams as 4 described by equations (8) and (9) will merge in approx-imately the same place as the drop stream as described by 6 equation (10) if ~ = L tanO since at x = L
7 (11 ) Y~ = YU = 1 a ~ ~ S
8 since:
9 (12) cos20 ~ 1 ~2 = 1- ( 1 )2 = 0 9997 (f O
FIG. 18 illustrates the jet trajectories from two 11 rows of nozzles when the jets 224 from the upper row are 12 deflected at a downward angle 0 relative to the normal of 13 the nozzle plate, and the lower row of jets 226 are directed 14 at an upward angle 9 with respect to the normal of th~
nozzle plate. It is to be appreciated that this is one of 16 the worst case conditions for non-parallel jet trajectories 17 from respective rows of nozzles to be guttered in a single 18 gutter. For a deflection plate having a length of 0.3 19 inches and an angle 6 of 1, then = O . 3 which - 0.005 57.3 inches. These are the dimensions set forth for the ink jet 21 printing system in FIG. 13, and it is seen that with these 22 dimensions the jets 224 and 226 will strike the gutter in 23 approximately the same position with the same deflection 24 voltage applied to both jets.
FIG. 19 illustrates a nozzle plate 228 having 26 laterally staggered rows of nozzles 230, 232, 234 and 236, 27 with the jets 238 and 240 from the rows 230 and 232, re-28 spectively, being directed at a downward angle towards a 29 printing medium ~073959 1 242, and wLtl- ~ets 244 and 246 from rows 234 and 236, respect-2 lvely, belng dlrected at an upward angle towards the printing 3 medium 2/~2. It ls seen that the distance the drops emanating 4 from rows 232 and 234 have to travel are substantially the same, and that the distance the drops from the rows 230 and 236 6 have to travel are also substantially the same. Further, it 7 is seen that the distance the drops from the rows 230 and 236 8 have to travel is farther than the distance the drops from the 9 rows 232 and 234 have to travel. Accordingly, drops emanating from the rows 230 and 236 must have a print signal applied to 11 them at a time ~ earlier than print signals which are applied 12 to the droplets emanating from rows 232 and 234. In other words 13 the drops emanating from the rows 232 and 234 have print signals 14 applied to them which are delayed relative to the print signals for rows 230 and 236. This is seen more clearly in relation 16 to FIG. 20, wherein FIG. 20A and FIG. 20D are the print signals 17 applied to drops emanating from rows 230 and 236, respect-18 ively, whereas the print signals illustrated in FIGS. 20B and 19 20C are the print signals applied to drops emanating from rows 232 and 234. Since the print signals applied to drops 21 from rows 230 and 236 occur at the same time, they may be 22 driven from a common timing source. The print signals applied 23 to drops from rows 232 and 234 may be driven .from another 24 common driving source. Accordingly, for a system as illus-trate~ in FIC. 19 the timing and delay networks utilized may 26 be reduced by a factor of 2 relative to known laterally stagger-27 ed printing systems which have a different timing sequence for 28 each row. It is to be appreciated, however, that the actual :~ 10739S9 1 psth length differences are typlcally very small and that for 2 many printing applications delay networks may be unnecessary.
3 For example~ wlth reference to FIG. 19, if the distance between 4 ad~acent rows are each 0.016" and the distance between nozzle , plate 228 and printing medium 242 i9 0.5", the maximum path 6 length difference for drop streams is about 0.0005". For 7 many printing applications, the drop placement error caused 8 by this path length difference is negligibly small, so that 9 delay networks would not be needed which greatly simplifies the circuitry.
11 As set forth in the previously referenced patent 12 application Serial No. 591,984 of Hendriks, guard jets may 13 be utilized to prevent aerodynamic retardation of droplet 14 streams which are to be used for printing. That is, droplet streams on tlle perimeter of an àrray are continuously guttered 16 to set up an air flow which prevents aerodynamic retardation 17 of droplet streams emitted from nozzles on the interior of the 18 array. In ~IG. 21, a nozzle array 248 includes a plurality 19 of membrane-type nozzles in which nozzles 250 and 252 on the perimeter of thP array have their respective orifices 254 and 21 256 offset in an upward direction with respect to the orifices 22 of the remaining nozzles 258, 260 and 262. Also, the orifices 23 254 and 256 may be made larger than the orifices of the other 24 nozzles such that the emitted droplets are larger and create a greater air flow. Charging and deflection electrodes are 26 not shown for clarity of the drawing. For the system shown, 27 the droplet streams emanating from the nozzles 250 and 252 are 28 at a downward angle with respect to the normal of the plane of 2g the nozzle plate and are aimed at a gutter 264 such that the droplets from the nozzle 250 and 252 are continuously guttered 1 and require no charging and/or deflection voltages. The drop-2 let streams emanating from the interior of the array, namely 3 from the nozzles 258 and 260 and 262 are selectively charged 4 and accordingly guttered in accordance with standard ink jet printing practices while not requiring complex electronic 6 circuitry to compensate for the normal aerodynamic drag of 7 printing droplets on the exterior of the array.
Claims (19)
1. In a jet printer including a nozzle plate having at least two rows of nozzles, with the nozzles in one row being staggered with respect to the nozzles in another row, a method of printing at least a portion of a line at a time on a printing medium, wherein said line is comprised of a plurality of dot positions, said method com-prising the steps of:
directing the jets from one row of nozzles towards a selected first group of non-adjacent dot positions on said line on said printing medium; and directing the jets from another row of nozzles, in a non-parallel trajectory with respect to the trajectory of the jets from said one row of nozzles, towards a selected second group of non-adjacent dot positions on said line on said printing medium.
directing the jets from one row of nozzles towards a selected first group of non-adjacent dot positions on said line on said printing medium; and directing the jets from another row of nozzles, in a non-parallel trajectory with respect to the trajectory of the jets from said one row of nozzles, towards a selected second group of non-adjacent dot positions on said line on said printing medium.
2. The method of Claim 1, including the step of:
selecting for printing certain ones of the drop-lets forming each of said jets, and guttering in a single gutter the unselected drop-lets from the jets emanating from the respective rows of nozzles.
selecting for printing certain ones of the drop-lets forming each of said jets, and guttering in a single gutter the unselected drop-lets from the jets emanating from the respective rows of nozzles.
3. In a jet printer including a nozzle plate having at least two rows of nozzles, with the nozzles in one row being staggered with respect to the nozzles in another row, a method of printing at least a portion a line at a time on a printing medium, wherein said line is com-prised of a plurality of dot positions, said method comprising the steps of:
directing the droplets emanating from one row of nozzles towards a selected first group of non-adjacent dot positions of said line on said printing medium;
directing the droplets from another row of nozzles, in a non-parallel trajectory with respect to the trajectory of the droplets from said one row of nozzles, towards a selected second group of non-adjacent dot positions of said line on said printing medium;
selecting the droplets emanating from said one and said another row of nozzles which are to be used for printing; and guttering in a single gutter the unselected droplets emanating from the respective nozzles.
directing the droplets emanating from one row of nozzles towards a selected first group of non-adjacent dot positions of said line on said printing medium;
directing the droplets from another row of nozzles, in a non-parallel trajectory with respect to the trajectory of the droplets from said one row of nozzles, towards a selected second group of non-adjacent dot positions of said line on said printing medium;
selecting the droplets emanating from said one and said another row of nozzles which are to be used for printing; and guttering in a single gutter the unselected droplets emanating from the respective nozzles.
4. In a jet printer including a nozzle plate having at least two rows of nozzles, with the nozzles in one row being laterally staggered with respect to the nozzles in another row, a method of printing a line at a time on a printing medium, wherein said line is comprised of a plurality of dot positions, said method comprising the steps of:
directing, at a downward angle with respect to the plane of said nozzle plate, the droplets emanating from one row of nozzles towards a selected first group of non-adjacent dot positions on said printing medium; and directing, at an upward angle with respect to the plane of said nozzle plate, the droplets emanating from another row of nozzles towards a selected second group of non-adjacent dot positions on said printing medium.
directing, at a downward angle with respect to the plane of said nozzle plate, the droplets emanating from one row of nozzles towards a selected first group of non-adjacent dot positions on said printing medium; and directing, at an upward angle with respect to the plane of said nozzle plate, the droplets emanating from another row of nozzles towards a selected second group of non-adjacent dot positions on said printing medium.
5. The method of Claim 4, including the steps of:
selecting the droplets emanating from the respective rows of nozzles which are to be used for printing; and guttering in a single gutter the unselected drop-lets emanating from the respective rows of nozzles.
selecting the droplets emanating from the respective rows of nozzles which are to be used for printing; and guttering in a single gutter the unselected drop-lets emanating from the respective rows of nozzles.
6. In a jet printer including a nozzle plate having at least two rows of nozzles, with the nozzles in one row being laterally staggered with respect to the nozzles in another row, a method of printing at least a portion of a line at a time on 8 printing medium, wherein said line is comprised of a plurality of dot positions, said method comprising the steps of:
directing, at a substantially normal angle with respect to the plane of said nozzle plate, the droplets emanating from one row of nozzles towards a selected first group of non-adjacent dot positions on said printing medium;
directing, at a non-normal angle with respect to the plane of said nozzle plate, the droplets emanating from another row of nozzles towards a selected second group of non-adjacent dot positions on said printing medium;
selecting the droplets emanating from the respective rows of nozzles which are to be used for printing; and guttering in a single gutter the unselected drop-lets emanating from the respective rows of nozzles.
directing, at a substantially normal angle with respect to the plane of said nozzle plate, the droplets emanating from one row of nozzles towards a selected first group of non-adjacent dot positions on said printing medium;
directing, at a non-normal angle with respect to the plane of said nozzle plate, the droplets emanating from another row of nozzles towards a selected second group of non-adjacent dot positions on said printing medium;
selecting the droplets emanating from the respective rows of nozzles which are to be used for printing; and guttering in a single gutter the unselected drop-lets emanating from the respective rows of nozzles.
7, A nozzle plate for a jet printer, comprising:
a substrate having at least two rows of orifices, with the orifices in one row being laterally staggered with respect to the orifices in another row, and with the orifices in at least one row being misaligned relative to a selected reference line in the plane of said substrate.
a substrate having at least two rows of orifices, with the orifices in one row being laterally staggered with respect to the orifices in another row, and with the orifices in at least one row being misaligned relative to a selected reference line in the plane of said substrate.
8. The combination of Claim 7, wherein said substrate is a semiconductor substrate.
9. The combination claimed in Claim 8, wherein said semiconductor substrate is silicon.
10. The combination claimed in Claim 7, wherein said orifices are circular in cross-section.
11. The combination claimed in Claim 7, wherein said orifices are rectangular in cross-section.
12. The combination claimed in Claim 7, wherein said orifices are square in cross-section.
13. A nozzle plate for a jet printer, comprising:
a semiconductor substrate having at least two rows of nozzles formed therein, with the nozzles in one row being laterally staggered with respect to the nozzles in another row, with each nozzle having entrance and exit apertures of different cross-sectional area, and with the exit apertures of each of the nozzles in at least one row being axially misaligned with respect to the longitudinal center axis of their respective entrance apertures.
a semiconductor substrate having at least two rows of nozzles formed therein, with the nozzles in one row being laterally staggered with respect to the nozzles in another row, with each nozzle having entrance and exit apertures of different cross-sectional area, and with the exit apertures of each of the nozzles in at least one row being axially misaligned with respect to the longitudinal center axis of their respective entrance apertures.
14. The combination claimed in Claim 13, wherein said semiconductor substrate is a silicon substrate.
15. The combination claimed in Claim 14, wherein the entrance and exit apertures of each of the nozzles are rectangular in cross-section, with the entrance and exit apertures having different cross-sectional areas.
16. The combination claimed in Claim 15, wherein in one row of nozzles the cross-sectional areas of the entrance apertures are larger than the cross-sectional area of exit apertures, and in another row the cross-sectional area of the exit apertures are larger than the cross-sectional area of the entrance apertures.
17. The combination claimed in Claim 14, wherein each nozzle in each row has an entrance aperture of rectangular cross-section and an exit aperture of circular cross-section.
18. A nozzle array for a jet printer, comprising:
a silicon wafer of (100) crystal orientation, wherein the wafer normal is misaligned with respect to the (100) crystal axis, with two rows of nozzles formed therein, with the nozzles in one row being laterally staggered with respect to the nozzles in the other row, with each nozzle having entrance and exit apertures of different polygonal cross-sectional area, and with the exit aperture of each nozzle being axially misaligned with respect to the longitudinal center axis of the entrance aperture.
a silicon wafer of (100) crystal orientation, wherein the wafer normal is misaligned with respect to the (100) crystal axis, with two rows of nozzles formed therein, with the nozzles in one row being laterally staggered with respect to the nozzles in the other row, with each nozzle having entrance and exit apertures of different polygonal cross-sectional area, and with the exit aperture of each nozzle being axially misaligned with respect to the longitudinal center axis of the entrance aperture.
19. A nozzle array for a jet printer, comprising:
a silicon wafer of (100) crystal orientation, wherein the wafer normal is aligned with respect to the (100) crystal axis, with at least two rows of nozzles formed therein, with the nozzles in one row being laterally staggered with respect to the nozzles in another row, with each nozzle having a rectangular entrance aperture on one face of the wafer which tapers to a membrane on the other face of the wafer with a circular exit aperture formed in said membrane, and with the circular exit aperture of each of the nozzles in at least one row being axially misaligned with respect to the longitudinal center axis of the respective entrance apertures.
a silicon wafer of (100) crystal orientation, wherein the wafer normal is aligned with respect to the (100) crystal axis, with at least two rows of nozzles formed therein, with the nozzles in one row being laterally staggered with respect to the nozzles in another row, with each nozzle having a rectangular entrance aperture on one face of the wafer which tapers to a membrane on the other face of the wafer with a circular exit aperture formed in said membrane, and with the circular exit aperture of each of the nozzles in at least one row being axially misaligned with respect to the longitudinal center axis of the respective entrance apertures.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/645,974 US4014029A (en) | 1975-12-31 | 1975-12-31 | Staggered nozzle array |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1073959A true CA1073959A (en) | 1980-03-18 |
Family
ID=24591223
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA268,536A Expired CA1073959A (en) | 1975-12-31 | 1976-12-22 | Staggered nozzle array |
Country Status (8)
| Country | Link |
|---|---|
| US (1) | US4014029A (en) |
| JP (1) | JPS5285819A (en) |
| BR (1) | BR7608729A (en) |
| CA (1) | CA1073959A (en) |
| DE (1) | DE2648867C2 (en) |
| FR (1) | FR2337043A1 (en) |
| GB (1) | GB1519103A (en) |
| IT (1) | IT1068050B (en) |
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| JP5007766B2 (en) * | 2010-10-12 | 2012-08-22 | セイコーエプソン株式会社 | Inkjet head |
| US10894358B2 (en) | 2018-09-13 | 2021-01-19 | Xerox Corporation | Optimized nozzle arrangement for an extruder head used in an additive manufacturing system |
| US11040366B2 (en) | 2018-09-18 | 2021-06-22 | Canon Kabushiki Kaisha | Dispenser shield with adjustable aperture to improve drop placement and residual layer thickness |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US28219A (en) | 1860-05-08 | Chukn | ||
| US3373437A (en) * | 1964-03-25 | 1968-03-12 | Richard G. Sweet | Fluid droplet recorder with a plurality of jets |
| GB1432366A (en) * | 1972-06-30 | 1976-04-14 | Ici Ltd | Pattern printing apparatus |
| US3797022A (en) * | 1972-07-25 | 1974-03-12 | Mead Corp | Apparatus and method for reproduction of character matrices ink jet printer using read only memory |
| US3958255A (en) * | 1974-12-31 | 1976-05-18 | International Business Machines Corporation | Ink jet nozzle structure |
| US3921916A (en) * | 1974-12-31 | 1975-11-25 | Ibm | Nozzles formed in monocrystalline silicon |
| US3949410A (en) * | 1975-01-23 | 1976-04-06 | International Business Machines Corporation | Jet nozzle structure for electrohydrodynamic droplet formation and ink jet printing system therewith |
-
1975
- 1975-12-31 US US05/645,974 patent/US4014029A/en not_active Expired - Lifetime
-
1976
- 1976-10-28 DE DE2648867A patent/DE2648867C2/en not_active Expired
- 1976-11-18 GB GB48201/76A patent/GB1519103A/en not_active Expired
- 1976-11-29 FR FR7636406A patent/FR2337043A1/en active Granted
- 1976-12-09 JP JP14721976A patent/JPS5285819A/en active Granted
- 1976-12-10 IT IT30281/76A patent/IT1068050B/en active
- 1976-12-22 CA CA268,536A patent/CA1073959A/en not_active Expired
- 1976-12-28 BR BR7608729A patent/BR7608729A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| FR2337043B1 (en) | 1980-10-17 |
| BR7608729A (en) | 1977-10-25 |
| GB1519103A (en) | 1978-07-26 |
| JPS5285819A (en) | 1977-07-16 |
| DE2648867A1 (en) | 1977-07-14 |
| FR2337043A1 (en) | 1977-07-29 |
| US4014029A (en) | 1977-03-22 |
| JPS5431368B2 (en) | 1979-10-06 |
| IT1068050B (en) | 1985-03-21 |
| DE2648867C2 (en) | 1986-08-14 |
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