DE2132082A1 - Method and apparatus for recording information with fluid droplets - Google Patents

Description

PATENT LAWYERS

DR-CLAUS REINLÄNDER O > VW

DIPL-ING. KLAUS BERNHARDT ^ ¹ ' ^/

D-8 MONKS 6Q

K9 P1 D

STjSPHAN B ₀ SEARS Portola Valley and Belmont ₉ GaIo,

Method and apparatus for recording Information with fluid drops

Priority * June 29, 1970 - V.St.Ao - Ser _e ffb. 50 445 Summary of the revelation

Za is disclosed a recording apparatus and a method in which a Sohreibflüssigkeitsquelle a fropfenprojiaiereinriohtung supplied from which a series of drops is ejected to the recording liquid with so much energy 'through a nozzle in a discontinuous stream "is that a substantially straight path to a recording means The volume of each droplet is individually controlled by electrical impulses that are sent to the proJluster device by an electronic drive device. Several such projection devices can be used, which are connected in such a way that they control a device by means of which predetermined graphic characters are printed on a recording medium or be mapped.

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Background of the invention

The invention relates generally to a printing apparatus and method "is not worked in by means of arrival. Impact _f in which the printing liquid is ejected by a volume displacement of a nozzle and in particular to an apparatus and method".

Up to now, during printing, a printing ink has been applied to specially designed types or printing blocks ₉ and these have been caused to execute a mechanical stop on a recording medium, for example paper, in order to form an impression of the printing block. More recently, non-stroke printing machines have been developed in which patterns (alphabetic or numerical drawings, graphic characters and derglo) are laid down on a recording medium Mapping of characters in use, including chemically active and chemically inert processes, in which either fluids or solids are used as marking or printing media, and which "require either specially treated recording media or untreated recording media,"

Tasks and aggregation; the invention

The general object of the invention is to provide an improved Printing method and an apparatus for recording by means of Writing fluids as well as an improved drop detection device to create for use in such a device «

It is also the object of the invention to create a drop projecting device or a head from which drops can be dripped with a controlled volume in the direction, ^{optionally through e & te fc knowledge}

109882/1710. _o "/ ₅

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on a press-off device while responding to electrical signals projected «. .

It is also an object of the invention to provide an improved method and gate direction for recording alphabetic »numeric and graphic characters on a recording medium by means of deposition of small crimps of printing fluid to create the recording medium in an economical and reliable way ·

Another object of the invention is to provide a drop projecting device to create »which project droplets from a nozzle in response to electrical signals, and in which the volume of the drops can be controlled by the applied electrical signals.

Another object of the invention is to create a printing device that is simple and reliable Operation hate

The above and other objects of the invention will be accomplished solved by a plug projection device or a head, in which a nozzle is in communication with a fluid chamber, which is provided by a fluid container assigned to it is supplied · An electromechanical transducer is assigned to one wall of the chamber so that the volume the chamber rapidly in accordance with electrical pulse signals is changeable, whereby Pluidtropfen with a VoIu- = which depends on the electrical energy of the signals, cus of the nozzle are ejected ,, The invention relates also refers to a printing device in which a plurality of such printheads for printing various shaped characters, for example alphabetic, numeric and graphic characters, is used, as well as on the Method of printing such characters,

.9 ORIGINAL

1098 82/1710 °° / *

Brief description of the drawings

1 is a schematic representation of a recording apparatus having a drop projecting device according to the invention;

FIG. 2 is a top plan view of an embodiment of the FIGS. 1 plug projection device shown;

Pi ₀ '. Figure 3 is a section taken along line 3-3 in Figure 2; Fig. 4 is a graph showing the voltage applied to the plug projector;

Fig. 5 is a graph showing fluid pressure as a function of time;

Fig. 6 is a sectional view of the fluid projector and shows the piezoelectric element in its maximum Deflection;

Fig. 7 is a partial section similar to Fig. 6 and shows the piezoelectric Element as it returns to its rest position ·;

FIG. ₉ 3 is a detailed section similar to FIG. 6 and shows the piezoelectric element in its rest position;

Fig. 9 is a schematic representation of an apparatus, which is suitable to drop a variety of data onto a recording medium to project;

Fig. 10 is a schematic representation of another device for projecting a plurality of drops onto a display means;

Fig. 11 shows a with the recording device according to Fig. 9 or 10 created characters "

Description of the Preferred Embodiment

Figo 1 is a schematic representation of a device 11, used to record information on a record

Λ ** '. > .- 1098 82/17 10 ■ "..» / 5

Original

drying medium 12 is adapted _o The recording agent 12 is shown here as a gegenüber'der device 11 from a supply roll 13 to a take-up roll 14 movably Ea is noted, however, that the relative movement between the device 11 and the recording medium carried 12 in bsliebiger, may suitably the actual movement being carried out either by the device 11, the recording means 12 or both _o - - \

The apparatus 11 includes a paint container 16 which may be any suitable container for the particular printing fluid used. . or printing ink - can act "i) it supplies the dye container 16 through a pipe 17 to a drop projection device or a print head 18. Main electronic pulse generator 19 applies pulses to the print head 18 through a corresponding transmission device 21, for example wires" When a pulse is received of the drive apparatus 19 outputs the print head 18 a single separate drops 22 pressurized fluid from an opening 24 and projecting the same _o Each electrical pulse produces a single drop, the volume of which is controlled by the JSnergie of the applied pulse · in the in Fig.! shown Auaführungebeiapiel the drops form a line 23 on the recording medium 12 while the same is moved past the print head 1 <3

In order to accurately record information on the recording medium 12, a substantially straight path of the opening 24 on the print head 18 to the recording medium 12. " That is, the careful arrangement of the recording medium with respect to the device 11 then leads or vice versa to an impact of drops in a predeterminable pattern in accordance with the signals generated by the electronic drive device 19. For the best

109882/1710 ' ^{oo / 6}

To achieve recording of information »the drops ¹ should be of an exact and predeterminable shape and volume. In other words, each drop must be exactly like every other ore and must closely follow the electronic signals of the drive device 19 so that equally spaced signals also produce spaced drops of substantially uniform size.

w Flue 2 and 3 show a preferred Tropfenprojiziereinrichtung or a print head 18. The print head has a housing 36 on which a part of a pressure chamber 37 determined by the Hohr 17 printing ink 33 is supplied to the chamber from an ink reservoir 16 to a Binlaßkanal. The pressure chamber 37 has also an output channel 39 ', the upper Jand the chamber is formed by a pressure plate or a deflectable plate 41st This pressure plate 41 is preferably made of a piezoelectric material. In the exemplary embodiment shown here, the pressure plate consists of two piezoelectric plates "42 and 43", which are defanible in the transverse direction, "which are attached to one another by means of a conductive film 44, which is sandwiched between the two" and 47, respectively, which establish an electrical connection to the plate surfaces, an electrical connection to the external conductive coatings is made by means of wires 48 and 49, through which a voltage can be applied across the plate by applying a voltage to the two surfaces With adequate tension across the plates 42 and 43, the plate 42 contracts "while the plate 43 expands, causing the pressure plate 41 to flex inwardly into the pressure chamber and thereby change its volume and displace fluid" naturally pressure on the pressurized fluid in the chamber

10 9882/1710 --./7

o By applying pressure to the fluid in the chamber 37 the fluid is forced through the outlet channel 39 and projected in the direction of the impression means, as well as back along the pipe 17 against the hydrostatic column of the paint container o The end of the channel 39 ends in an opening 52 of the exact diameter, so that the diameter of the drop squeezed out of the printhead precisely controlled, is »The drop size is a function of the Voltage between plates 42 and 43, one pulse length and the diameter of the opening 52 o

The pressure plate 41 is in the housing 36 .by an appropriate Fastening device, for example by a lapoxy resin adhesive, held and received in the housing 36 of the print head, such as Fi ^. 3 showed Sin piezoelectric transducer, which has been found to be satisfactory for the printing plate 41 is that of the Clevlte Corporation, Cleveland, Ohio, transducers sold under the trademark "Biraorph".

Through the lines 48 and 49 electrical signals from an associated generator 19 are applied to the surfaces of the printing plate 41, which in turn converts the electrical signals into a displacement of the printing plate, whereby printing in the color is generated. Preferably, the generator 19 supplies electrical pulse signals from a selected amplitude and duration to control the force applied to the ink Energy »cause These rapid pressure pulses that individual • jiropfen be ejected 22 from .the opening 52 _o If no Bruck pulse is applied, the ink is due to the static pressure from the ink container 16 on the printing ink contained in the chamber 37 has a slight dome 56 which protrudes from the opening 52 ο

When applying Impuladruclc aeitena the plate 41 flows Printing ink from the chamber 37 through the outlet channel 39 into the

" ^J " 1 0 9 8 8 2/1 7 1 0 Wb Q * ®iNAL °

Output port 52 "print color is out of the opening 52 is ejected in accordance with the pulses as individual droplets" as schematically shown in Figo 3 * The drops 22 impinge on the recording medium 12 to ₉ and the relative movement between the print head and the recording medium leads to the formation of a line or other shape "depending on the direction and magnitude of the relative movement between the print head and the recording medium assigned to it"

The. Size of the inlet and outlet channel 38 and 39 is to some degree on the viscosity of the ink used, a pressure pulse to the plate 4-1 bestizaato Another tube wure for a starch viscous ink nötigo because a drop 22 from the outlet port 52 discharges, so the pressure also has a tendency to force ink back through inlet channel 38 against the pressure column formed by ink container 16 Amount of return flow when ejecting drops is limited = fluid that flows through a tube of length L with a velocity ν in a laminar flow * is subject to a retarding frictional force F according to the following equation:

F = 3 ffj L v,

where ff is the viscosity coefficient of the fluid "In addition, the static column of the paint container 16 has a tendency to force droplets out of the nozzle 52 instead of back into the inlet channel 33." A static column of 50.8 mm (2 inches) of water extends into the most cases _o \ / hen the Rückatrömung through the inlet channel 33 is not -begrenzt _Pii the Drucklrapuls may the part of the plate 41 significant amounts of energy wasting characterized in that a volume of großas .Druckfarbe by the iiinlaßkahal 38 auriickgedrängt and

O / J

Pressure in chamber 37 is not raised enough to expel a drop of paint 22 from nozzle 52 _{or the like}

The diameter of the outlet nozzle 52 influences the diameter of the droplet 22 _o The length and the diameter of the channel 39 Bellten be churned so that low friction losses are caused compared to those caused by the pressure column, the channel 38 and the pipe 17 "While a dome 56 is formed at the opening 52 when no pressure pulse is applied, the surface tension of the printing ink" prevents it from flowing out of the opening 52 o The permissible static pressure that can be applied by the ink container 16 can be as follows to express:'

c.g, .s .-. units,

where D is the diameter of the opening 52 and S is the surface tension constant of the printing ink »tiQnn. However, the soup should be stable at the opening 52, the ink should the front hexes of the housing 36 on the printhead 18 _o not be "benetzenο In other words, the natural contact angle between the ink and the front surface of the housing 36muß greater than 90 ° This Condition lccnn can be met if water-based printing inks are used and the front surface 57 of the housing 36 is provided with a Teflon coating. While coatings of leflon are also preferred on the surface 57, many other combinations of liquids are also preferred and solids at a contact angle of more than 90 ° can be used for the purpose of finding "

4 shows the input voltage to the crystal (the one in Pressure is transferred to the fluid) as a function of Time * The system remains in the rest position until an input voltage pulse 62 applied to the plate 41 at the time * «

* ßAD ORiGWAL

109882/1710

will o This voltage causes the piezoelectric Pressure plate 41 (Fig «3) bends and thereby the Pressure on the ink increased until it is about ten times the static pressure, because of the response time when bending the pressure plate 41 and the persistence The fluid causes the application of a voltage pulse en at time t | at a rapid rate, but not Immediate increase in pressure “The pulse is applied until time, tx, and it ends at t ,.

The pressure fluctuation shown in Figure ₀ 5) in which the pressure of t 63 at the time ^ static has tfert and tp to a maximum value at 64 at the time increases, "This high pressure acts as a driving force to the ink in the output port 52 and accelerates the same so that a drop of the ink starts to flow 22 from the nozzle 52 ₀ the nsxiinale fluid pressure is reached at point 64, but the pressure remains high "to the point 63 at time t ₀ as soon as a predetermined time has elapsed, ~ t to t - in Figure _s 4 and 5, the voltage of the electronic drive device 19 is switched back to the original voltage, and the pressure in the chamber 37 drops rapidly to a .Vert below the static value from, namely ated to 66 at the time t, , and then returns to the static ■ closed 67 at time t, - back _o The printing ink column in the Auslaukanal 39 is pushed out of the nozzle 52 by the increased pressure at 64 and is now at a high speed reached. This high speed overcomes the surface tension at opening 52 so that a drop 22 separates from opening §2 and follows a natural, essentially straight path to the recording medium, where the drop forms a point in line 23 each described to 3 in connection with the Figo 6 = "the volume of ejected color depends partly on the pulse-width 'of the charge d ₀ h ₀ represents time t | until

<BAD OBIC. 8 8 2/1710 " ^{j / 11}

t »as well as on the value of the voltage, i.e. on the applied jinergie »By changing this amount of time, you can use Generate miniature rfeise drops that have a single diameter have between -0.1016 mm and 0.6350 mm (4 and 25 mils) » The next applied pulse 63 kills the next drop from ο'The succession of the! drops is therefore through the Controllable frequency with which pulses are applied,

FIG. 6 shows a section through the fluid chamber 37 shown in FIG. 3.

This chamber opens at time t ~ (Fig. 5) »when the deflection has reached its highest level. The tension across the plate 41 has caused the crystal 42 to contract and the crystal 43 to expand, so that the plate is deflected into the chamber 37 and displaces a certain amount of dye. the viscosity of the ink, the length and diameter of the channel 33 as well as other above-described factors flowing a part of the displaced ink back into the tube 17 through the fJinlaßkanal 3NC _o the main effect of the displacement-ingung of the printing ink in the Kaumer 37 through the plate is however, in pressing a plug or a column 101 out of the D'ise 52 ο

7 shows the pressure plate 41 still in the state of its maximum Deflection, but after the voltage supply has dropped to 66 according to FIG. 5 at time t ^. The plate 41 now begins its return movement to the starting position, since the voltage input to the crystal is reversed again. The acceleration of the plug or where the pillar 101 has changed also vice versa «, however, part of the column has reaches a speed of flight and forms a drop 102 '. The drop 102 separates from the plug 101, which

10g882 / 1710 _8ÄDOFiiam _ ... / 12

slows down, and leaves the plug end, which is still in connection with the paint supply within the chamber 37 standso

Figo 8 shows the system at time t ^ according to Figo 5 o Die Plate 41 has returned to its operational position at time tf-! those in the curve according to FIG 67 indicated late In the meantime, however, the negative component of the pressure pulse lake, 66 in FIG. 5, leads to the fact that the column of paint 101 is sucked back into the channel 39, as * Fig. 8 showed. At the same time, the surface tension of the Droplet 102 causes it to take on a spherical shape o The plant returns after each impulse that leads to formation of a drop moves back to the equilibrium state ο

The maximum value 64 of the pressure exerted on the ink is suitably in the range of 0.07 to 1.4 kgf / cm (1 to 20 psl). A table of parameters for an apparatus and, as an example below emäß Fig. 1 to 3 specified, are fast with which high-quality color drops provided könnan _o

Table I. 1000 points / sec Printing speed 0.035 kgf / cm ² static pressure (0.5 p.s.i.) 0.35 kg / cm ² Peak pulse pressure (5.0 ps.i. • 180 V Pulse voltage 50 / U s Pulse width 0.127 mm (0.005 opening diameter

Figure 9 is a schematic representation of an apparatus similar to Figo 1, but which is suitable for coherent ...

109882/1710

pattern »for example alphabetic and numeric characters to print o This is achieved in that a grove of print heads 111-120 is controlled independently of one another by the electronic drive device 19 o The print heads 111-120 are arranged vertically in a stack 110 so that they can be simultaneously of 1 to 10 crimps can eject · Assuming a letter "ϊ" is to be printed according to the invention, Figo 11 shows how the letter "1 ^H can be built up from an arrangement of colored dots, the nine possible positions on the X- Axis and ten possible positions on the Y-axis. With the gate direction shown in Fig. 9, the letter T can be created so that the stack 110 is brought into position 1 on the X-axis (Fig. 11) and the print head 111 is actuated so that a point appears at position ten on the Y-axis, the stack 110 is then moved to position two on the X-axis, the printhead 111 is actuated again, and forms another point in position ten on the Y-axis o This method is continued until the stack 110 is arranged in position five on the Y-axis; at this point all ten print heads are actuated so that drops are ejected from each of the print heads 111-120. As a result, drops are formed in positions one to ten on the Y-axis, which represent the vertical component of the letter "T". Thereafter, when moving the stack 110 to positions six to nine on the X axis, only the print head 111 is actuated in order to print dots in position ten on the Y axis in any case.

»/ Alirend Fig. 9 shows ten printheads a 111-120, it has been found that legible characters can also be produced with only five vertical positions. However, between seven and ten positions on the printhead preferred for alphabetic or numeric characters of greater clarity

produce.

BAD 'QfHGINAL

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The stack is on a threaded support 121 attached, which throws together with a guide screw 122 ο The guide screw is at its ends 123 and 124 rotatably mounted and driven by a stepping motor 126. The number of threaded eyes per unit length the rod 122 is chosen so that each of the stepper motor 126 triggered rotation step of the printhead in the horizontal direction by the distance between adjacent columns moved further on the X-axis according to FIG. In this way the print head is advanced to the next position along the X-axis according to FIG. 11 with each step of the stepping motor 126. vürt3bewegto

Fig. 10 shows a device in which a plurality of print heads 131-140 side by side instead of one above the other as are arranged in the embodiment according to Fig. 9 * The recording medium 12 is moved in a vertical direction past the heads to record characters and other representations to print, it should be noted that the marriage the print head either vertically or horizontally, depending on your requirements can be arranged »For example, a stack of nozzles of vertically arranged piezoelectric Plates are supplied. Likewise, the relative movement between the recording medium and the print head can be either be carried out vertically or horizontally.

It is therefore obvious that alphabetic and numerical characters according to the invention can be printed without a stop between the recorder and the recording medium "individual" clods but are ejected in a substantially straight path towards the recording medium * without any electrostatic control or associated high voltages would be required _D

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^BATH ° ^{m [ml}

Claims (1)

Κ9 Ρ1 D - 15 - Claims Method ζιω projecting fluid drip from an opening, characterized in that a limited volume of a writing fluid is determined, unu that the volume is suddenly reduced, bo that Droplets are projected from the opening in the direction of a ^ a associated recording medium. » 2ο method nacli claim 1, characterized _f in that the droplets are ejected in that a plug of fluid is accelerated so that it projects out of the opening, while still communicating with de © remaining fluid reservoir in conjunction that the 'JJropfen of the .Stop is separated and that the part of the remaining fluid supply that protrudes from the nozzle after the separation is retrieved. 3. The method according to claim 1 or 2, characterized in that the diameter of the drops between 0.1016 and is 0.6350 min (4 and 25 mils), 4ο method according to one of claims 1 to 3, characterized It is accepted that the printing speed is between 100 and 3000 drops / second is Is 5. A method according to any one of claims 1 to 4, characterized in that the pressure of the writing fluid by _t rus leash ti surface energy to the Xropfen transmitted, La range of .0,07 to 1.40 kgf / cm ² (1 to 20 psi), 6ο. Device for. Projecting liquid droplets for extending the method according to one of claims 1 to 5, with a Plwidkammer _t an opening communicating with the fluid chamber and Qiner with the 109882/17 10 "" "/ 16 Fluid chamber for supplying fluid to the chamber-related device, characterized by a volume displacement device that responds to electrical signals responds to displace fluid in the Kacuner " so that a single fluid drop is released from the opening will, and at least a 'jeil the wall of the Chamber formed Device according to claim 6, characterized in that the volume displacement device ^{comprises a piezoelectric x J} slat which is deflected into the chamber in order to displace a volume of fluid in accordance with electrical signals applied to the plate. 8o. Device according to claim 7 »characterized» that the piezoelectric plate zv / ei extensible in the transverse direction piezoelectric plates on v / eist which are attached to each other and arranged so that they move in the transverse direction stretching in opposite directions in order to flex according to the electrical signals applied «, 9ο Device according to claim 7 or 3, characterized in that the opening is arranged at the end of a channel which is connected to the chimney _{B G} 1oo device according to claim 9 »characterized in that the surface of the opening is not wettable" 11. Device according to one of claims 6 to 10, dadurc'i characterized in that the device communicating with the Kacaraer for supplying fluid has an inlet channel having, and that the opening with the chamber over an outlet channel is in communication, wherein the opening and the inlet and outlet channels are chosen so that the Fluidströmuiig controlled in such a way through the opening 109882/1710. -./17 "ORIGINAL is that goiters are projected out of the opening-, 12 ο Device for recording on a recording medium by means of a writing fluid. with a facility; according to any one of claims 6 "to 11, characterized in that a device is provided that _g generates a relative movement between the means for projecting fluid droplets, and the recording means for selectively a Muater of fluid drops on the on ze ichnungsmittel on zuzeichneiio 13o writing device, characterized in that a plurality of devices for projecting drops of liquid according to one of claims 6 to 12 with one another are cooperatively provided, and that the control devices thereof respond to an input signal in order to generate pulses in selected fluid projection devices generate zta * Il 109882/1710 4t Blank page