CA2029527C - Temperature sensor for an ink jet printhead - Google Patents
Temperature sensor for an ink jet printheadInfo
- Publication number
- CA2029527C CA2029527C CA002029527A CA2029527A CA2029527C CA 2029527 C CA2029527 C CA 2029527C CA 002029527 A CA002029527 A CA 002029527A CA 2029527 A CA2029527 A CA 2029527A CA 2029527 C CA2029527 C CA 2029527C
- Authority
- CA
- Canada
- Prior art keywords
- printhead
- temperature
- resistive
- resistor
- ink
- 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 - Lifetime
Links
- 238000009966 trimming Methods 0.000 claims abstract description 10
- 229910021420 polycrystalline silicon Inorganic materials 0.000 claims abstract description 9
- 229920005591 polysilicon Polymers 0.000 claims abstract description 9
- 239000010409 thin film Substances 0.000 claims abstract description 6
- 239000000758 substrate Substances 0.000 claims description 19
- 238000010438 heat treatment Methods 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical group [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- 238000004891 communication Methods 0.000 claims description 2
- 238000009529 body temperature measurement Methods 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 10
- 239000000976 ink Substances 0.000 description 41
- 238000007639 printing Methods 0.000 description 8
- 239000010408 film Substances 0.000 description 3
- 238000007641 inkjet printing Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 2
- 230000035945 sensitivity Effects 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 230000001133 acceleration Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000000593 degrading effect Effects 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 230000037406 food intake Effects 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000005499 meniscus Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000002441 reversible effect Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
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
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
- B41J2/04563—Control methods or devices therefor, e.g. driver circuits, control circuits detecting head temperature; Ink temperature
-
- 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
- B41J2/015—Ink jet characterised by the jet generation process
- B41J2/04—Ink jet characterised by the jet generation process generating single droplets or particles on demand
- B41J2/045—Ink jet characterised by the jet generation process generating single droplets or particles on demand by pressure, e.g. electromechanical transducers
- B41J2/04501—Control methods or devices therefor, e.g. driver circuits, control circuits
- B41J2/0458—Control methods or devices therefor, e.g. driver circuits, control circuits controlling heads based on heating elements forming bubbles
-
- 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
- B41J2/14016—Structure of bubble jet print heads
- B41J2/14153—Structures including a sensor
-
- 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
- B41J2/16—Production of nozzles
- B41J2/1601—Production of bubble jet print heads
- B41J2/1604—Production of bubble jet print heads of the edge shooter type
-
- 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
- B41J2/16—Production of nozzles
- B41J2/1621—Manufacturing processes
- B41J2/1632—Manufacturing processes machining
- B41J2/1634—Manufacturing processes machining laser machining
Abstract
An ink jet printhead is fabricated with a resistive temperature sensor formed adjacent to the heater resistors and, in a preferred embodiment, of the same material. Temperature sensing variations between a plurality of printheads used in the same printer is achieved by trimming the thermistors to the desired resistance value while holding the printhead at the nominal set temperature. In one embodiment, the heater resistor and thermistor are formed within the same polysilicon layer, and the resistor trimmed therein. In a second embodiment, a thick or thin film resistor is formed or bonded in series with the polysilicon thermistor with the trimming being accomplished at the thick, or thin film resistor.
Description
202~52~
TEMPERATURE SENSOR FOR AN INK JET PRINTHEAD
BACKGROUND AND INFORMATION DISCLOSURE STATEMENT
This invention relates to a bubbie ink jet printing system and, more particularly to a printhead having a temperature sensitive material incorporated therein which serves as a temperature sensor to effectively control heat generated during the printing operation.
Bubble jet printing is a drop-on-demand type of ink jet printing which uses thermal energy to produce a vapor bubble in an ink-filled channel that expels a droplet. A thermal energy generator (printhead), is located in the channels near the nozzle a predetermined distance therefrom. A plurality of resistors are individually addressed with a current pulse to momentarily vaporize the ink and form a bubble which expels an ink droplet. As the bubble grows, the ink is ejected from a nozzle and is contained by the surface tension of the ink as a meniscus. As the bubble begins to collapse, the ink still in the channel between the nozzle and bubble starts to move towards the collapsing bubble, causing a volumetric contraction of the ink at the nozzle and resulting in the separating of the bulging ink as a droplet. The acceleration of the ink out of the nozzle in which the bubble is growing provides the momentum and velocity of the droplet in a substantially straight line direction towards a recording medium, such as paper.
A problem with prior art printhead operation is the increase in temperature experienced by a printhead during an operational mode.
With continued operation, the printhead begins to heat up, and the diameter of the ink droplet begins to increase resulting in excessive drop overlap on the recording media thereby degrading image quality. As the printhead experiences a further heat buildup, the ink temperature may rise to a point where air ingestion at the nozzle halts drop formation completely It has been found that, at about 65 for a typical ink, printhead operation becomes unreliable. There is also a lower temperature limit for reliable operation which varies for different inks and device geometries.
This limit might, for example, be about 20C for an ink and device designed 2029~7 to function reliably up to, for example, 60C. At the same time, it is desirable to offer an extended range of ambient operating temperature, such as 5C to 35C, so that it will be necessary to provide for warming up the printhead. It is also desirable to minimize the time required to warm up the printhead, so that first copy (print) out time is acceptable. The printhead characteristics and machine environment requirements have the following impact on the thermal design of the system. The generation of heat during operation (which becomes a greater problem as print speed, duration, and density increase) makes it necessary that the printhead be connected to a heat sink, which is efficient in transferring heat away from the printhead. The efficiency of the heat transfer away from the printhead will be enhanced by the cooler the heat sink is relative to the printhead.
Because of the range of ambient temperatures to be encountered (assumed to be 5C to 35C, but not limited to that range), and because of the temperature uniformity requirement, and further because it is less complicated and less expensive to control temperature by heating than by cooling, it is advantageous to set the nominal printhead operating temperature at or near the maximum ambient temperature encountered.
Because of the desired minimal first copy (print) out time, as well as the desired efficiency of the heat sink, it is also advantageous to situate a temperature sensor and heater as close as possible (thermally) to the printhead, and as far as possible (thermally) from the heat sink.
Temperature regulation typically is achieved in the prior art by using a combination of a temperature sensor and a heater in a feedback loop tied into the printhead power source. For example, U.S. Patent 4,250,512 to Kattner et al. discloses a heating device for a mosaic recorder comprised of both a heater and a temperature sensor disposed in the immediate vicinity of ink ducts in a recording head. The heater and sensor function to monitor and regulate the temperature of a recording head during operation. Column 3, lines 7-24 describes how a temperature sensor, a thermistor, a heating element, and a resistor operate in unison to maintain the recording head at an optimum operational temperature to maximize printing efficiency. U.S. Patent No. 4,125,845 to Stevenson, Jr.
discloses an ink jet printhead temperature control circuit which uses a heater and a temperature sensing device to maintain a recording head temperature above the preset temperature level. An output from the temperature sensing device drives an electrical heater which regulates the recording head temperature. The temperature sensing device is a resistive element attached to the bottom side of the printhead by thick film techniques. U.S. Patent No. 4,704,620 to Ichihashi et al. discloses a temperature control system for an ink jet printer wherein the temperature of an ink jet printhead is controlled by a heater and a temperature sensor which collectively regulate heat transfer to maintain an ink jet printhead within an optimum stable discharge temperature range. The temperature control circuit, as shown in Figure 7 of the patent, utilizes an output from a comparator circuit and control signals from a signal processing circuit to regulate printhead temperature based on the output from the temperature sensor. U.S. Patent No. 4,791,435 to Smith et al. discloses a thermal ink jet printhead temperature control system which regulates the temperature of a printhead via a temperature sensing device and a heating component. The temperature sensing device, comprised of either a collection of transducers or a single thermistor closely estimates the temperature of the ink jet printhead and compensates for an unacceptable low printhead temperature by either cooling or heating the printhead as needed. U.S. Patent No. 4,686,544 to Ikeda et al. discloses a temperature control system for "drop-on-demandn ink jet printers wherein a heat generating electrode, positioned between layers of insulating and resistive material of a printhead substrate, controls the temperature of the printhead during operation, Column 4, lines 7-25, describes how an electrothermal transducer delivers the heat required to maintain the ink jet printhead at an optimum temperature level to maximize efficiency printing efficiently. U.S. Patent No. 4,636,812 to Bakewell, while disclosing a thermal printhead, also teaches using a heater and temperature sensor supported within a laminated layer nearthe marking resistors.
U.S. Patent No. 4,738,871 to Watanabe et al. discloses a heat-sensitive recording head which makes use of laser-made holes to control 2029S2~
the resistance of the heater resistors. These laser-made holes are also used to control the temperature which is directly related to the resistance. A
method for making the iaser holes is also provided.
U.S. Patent No. 4,772,866 to Willens discloses a device including a temperature sensor. The temperature sensor uses the semiconductor material (polysilicon) which is already part of the device.
U.S. Patent No. 4,449,033 to McClure et al. discloses a thermal printhead temperature sensing and control system. A sensor is made of a thermo-resistive material (Col. 4, lines 23-24) which runs parallel to the printhead leads. Means are provided for the temperature control circuitry for the printhead. The sensor can also sense a temperature change in a single printhead element (Col. 1, line 55). The sensor is situated above the printhead leads and separated from them by glass (Fig. 2, Numbers 10, 11).
The above references disclose various types of discrete temperature sensors which provide sensitivity for the particular system that they are used in. However, more precise temperature sensing and heater control may be required for certain print system depending upon printhead geometry, print speeds, and ambient operating temperature range. An optimum physical arrangement for a heater and sensor is to be in close proximity to the printhead. An optimum material from a manufacturing and economic standpoint is, for the temperature sensor to be formed from the same material as the resistor heating elements in the printhead. This goal, however, has not been achieved because the fabrication tolerances for the resistor are not sufficient for the purposes of forming sufficiently accurate thermometers on a plurality of printheads. In other words, it is heretofore not been possible to fabricate a plurality of printheads which may be required for a specific print system so that each temperature sensor for each printhead would be within a specific and consistent temperature tolerance range. A typical temperature coefficient of resistance of polysilicon is 1 x 10 -3/C and a typical resistance tolerance is + 5%. Thus, a thermistor formed near the resistor array would be inaccurate by as much as + 50C. Depending on the temperature control and printhead 202~2~
-performance, sensitivity to temperature for a specific system, a thermometer would have to obtain an accuracy of + 1 -5C.
Thus, heretofore, it has not been possible to form a thermistor in close proximity to the printhead and of the same material as the heaters or the printhead. According to the present invention, however, it has been found that the accuracy of a thermistor of the same material as the printhead heater elements can be improved so that its accuracy is within the desired temperature range (of 1-5C) by trimming the thermistor, or, by trimming an external resistor in series with the thermistor while holding the printhead at a desired temperature control set point. More particularly, the present invention is directed towards a thermal ink jet printhead including: a substrate support; an ink heating resistive layer disposed within said substrate comprising individual resistive elements in communication with an adjacent ink filled channel; and a second temperature sensitive resistive layer disposed within said substrate and proximate to said resistive layers, said temperature sensitive layer having an electrical connection to a temperature control circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic perspective view of a bubble jet ink printing system incorporating the present invention.
Figure 2 is an enlarged schematic perspective view of the printhead of Figure 1.
Figure 3 is a cross-sectional side view of the printhead shown in Figure 2.
Figure 4 is a top plan view of the printhead shown in Figure 3.
Figure 5 is an alternate embodiment of the print head shown in Figure 4.
DESCRIPTION OF THE INVENTION
A typical carriage type bubble jet ink printing device 10 is shown in Fig. 1. A linear array of droplet producing bubble jet channels is housed in the printhead 11 of reciprocating carriage assembly 29. Droplets 12 are propelled to the recording medium 13 which is stepped by stepper motor 2029~27 16 a preselected distance in the di rection of arrow 14 each ti me the printing head traverses in one direction across the recording medium in the direction of arrow 15. The recording medium, such as paper, is stored on supply roll 17, and stepped onto roll 18 by stepper motor 16 by means well known in the art.
The printhead 11 is fixedly mounted on support base 19 which is adapted for reciprocal movement by any well known means such as by two parallel guide rails 20. The printhead and base comprise the reciprocating carriage assembly 29 which is moved back and forth across the recording medium in a direction parallel thereto and perpendicular to the direction in which the recording medium is stepped. The reciprocal movement of the printhead is achieved by a cable 21 and a pair of rotatable pulleys 22, one of which is powered by a reversible motor 23.
The current pulses are applied to the individual bubble generating resistors in each ink channel forming the array housed in the printing head 11 by conduits 24 from controller 25. The current pulses which produce the ink droplets are generated in response to digital data signals received by the controller through electrode 26. The ink channels are maintained full during operation via hose 27 from ink supply 28.
Fig 2 is an enlarged partially sectioned, perspective schematic of the carriage assembly 29 shown in Fig. 1. The printhead 11 includes substrate 41 containing the electrical leads 47 and bubble generating resistors 44 Printhead 11 also includes channel plate 49 having ink channels 49a and manifold 49b Although the channel plate 49 is shown in two separate pieces 31 and 32, the channel plate could be an integral structure. The ink channels 49a and ink manifold 49b are formed in the channel plate piece 31 having the nozzles 33 atthe end of each ink channel opposite the end connecting the manifold 49b. The ink supply hose 27 is connected to the manifold 49b via a passageway 34 in channel plate piece 31 shown in dashed line. Channel plate piece 32 is a flat member to cover channel plate piece 31 and together form the ink channel 49a and ink manifold 49b as they are appropriately aligned and fixedly mounted on substrate 41.
._ Referring now to Figures 3 and 4, Figure 3 shows (not to scale) a cross-sectional view of the substrate 41 of Figure 2. Substrate 41 is comprised of a crystal material such as silicon. A resistive thermistor layer 50, formed by standard thin film or integrated circuit fabrication methods upon the silicon substrate, is connected to an outside temperature control circuit 52 by electrode leads 54. The resistive heating elements 44 are connected by common electrodes 51 which are pulsed by signals sent along electrodes 47 to expel ink from nozzle 33.
According to a first aspect of the present invention, the resistive thermistor layer 50 is trimmed to a preselected resistance value by a laser trimming operation which is implemented at a time that the printhead is held at the set point temperature of interest. Since a laser trimming operation requires exacting tolerances, a simplified trimming operation can be performed by using the embodiment shown in Figure 5. There, thick film, or, alternately, thin film resistor element 58 has been formed on the surface of substrate 41, or adjacent substrate (not known) and connected in series with thermistor layer 50. The trimming operation is then performed on resistive element 58 until the desired resistance is achieved. For this embodiment, the total error in temperature reading from instability or temperature variation of the trimmed resistor will be in the order of 1C or less which is sufficiently accurate for a thermistor for thermal ink jet printing purposes. The external resistor to be trimmed may be formed as part of a hybrid circuit which also provides electrical interconnection to the printhead die. Alternatively, the resistor 58 to be trimmed may be added as a discrete chip resistor located on an adjacent substrate. For this example, the printhead may be packaged as a chip-on-board.
It will be appreciated that the above technique results in the elimination of resistance variability between a plurality of printheads being used in the same system, since all thermistors will operate in agreement with each other at the set temperature point of interest.
For the Figure 4 embodiment the nominal resistance of the polysilicon thermistor 50 is about 20KQ, and its temperature coefficient of resistance is about 1x10-3/C (i.e., a change of 1C corresponds to a 2~29527 thermistor resistance change of 20Q). Since the tolerance of the polysilicon resistor 44 will need to be kept within about + 5% from part to part and batch to batch, the thermistor will also be approximately this uniform (it may be slightly less uniform because of its high aspect ratio). In order to make the total resistance uniform at the set point, the trimmed resistance will need to vary over a range of about 2KQ, for example, from 3KQ (for devices in which the polysilicon is at its maximum resistance) to 5KQ (for devices in which the polysilicon is at its minimum resistance). According to resistor paste specifications, the stability of a laser trimmed resistor during its lifetime (under load and under heat) is typically 0.2%. A 5KQ trimmed resistor should be uniform to 10Q during its lifetime, corresponding to an apparent temperature change of 0.5C. The temperature coefficient of resistance of the thick film resistor is specified as 0 + 1x10-4/C. The temperature range of the substrate on which the external resistor 58 sits will almost certainly not exceed +20C during operation of the printer.
Th is wou Id correspond to a resistance change that wou Id not exceed + 1 OQ, corresponding to an apparent temperature change of +0.5C. Thus, the total temperature error due to changes in the externally trimmed resistor will be on the order of 1C or less.
While the invention has been described with reference to the structure disclosed, it is not confined to the specific details set forth. For example, while a carriage was shown with a single printhead, the invention may be used in other configurations such as a page width printer.
TEMPERATURE SENSOR FOR AN INK JET PRINTHEAD
BACKGROUND AND INFORMATION DISCLOSURE STATEMENT
This invention relates to a bubbie ink jet printing system and, more particularly to a printhead having a temperature sensitive material incorporated therein which serves as a temperature sensor to effectively control heat generated during the printing operation.
Bubble jet printing is a drop-on-demand type of ink jet printing which uses thermal energy to produce a vapor bubble in an ink-filled channel that expels a droplet. A thermal energy generator (printhead), is located in the channels near the nozzle a predetermined distance therefrom. A plurality of resistors are individually addressed with a current pulse to momentarily vaporize the ink and form a bubble which expels an ink droplet. As the bubble grows, the ink is ejected from a nozzle and is contained by the surface tension of the ink as a meniscus. As the bubble begins to collapse, the ink still in the channel between the nozzle and bubble starts to move towards the collapsing bubble, causing a volumetric contraction of the ink at the nozzle and resulting in the separating of the bulging ink as a droplet. The acceleration of the ink out of the nozzle in which the bubble is growing provides the momentum and velocity of the droplet in a substantially straight line direction towards a recording medium, such as paper.
A problem with prior art printhead operation is the increase in temperature experienced by a printhead during an operational mode.
With continued operation, the printhead begins to heat up, and the diameter of the ink droplet begins to increase resulting in excessive drop overlap on the recording media thereby degrading image quality. As the printhead experiences a further heat buildup, the ink temperature may rise to a point where air ingestion at the nozzle halts drop formation completely It has been found that, at about 65 for a typical ink, printhead operation becomes unreliable. There is also a lower temperature limit for reliable operation which varies for different inks and device geometries.
This limit might, for example, be about 20C for an ink and device designed 2029~7 to function reliably up to, for example, 60C. At the same time, it is desirable to offer an extended range of ambient operating temperature, such as 5C to 35C, so that it will be necessary to provide for warming up the printhead. It is also desirable to minimize the time required to warm up the printhead, so that first copy (print) out time is acceptable. The printhead characteristics and machine environment requirements have the following impact on the thermal design of the system. The generation of heat during operation (which becomes a greater problem as print speed, duration, and density increase) makes it necessary that the printhead be connected to a heat sink, which is efficient in transferring heat away from the printhead. The efficiency of the heat transfer away from the printhead will be enhanced by the cooler the heat sink is relative to the printhead.
Because of the range of ambient temperatures to be encountered (assumed to be 5C to 35C, but not limited to that range), and because of the temperature uniformity requirement, and further because it is less complicated and less expensive to control temperature by heating than by cooling, it is advantageous to set the nominal printhead operating temperature at or near the maximum ambient temperature encountered.
Because of the desired minimal first copy (print) out time, as well as the desired efficiency of the heat sink, it is also advantageous to situate a temperature sensor and heater as close as possible (thermally) to the printhead, and as far as possible (thermally) from the heat sink.
Temperature regulation typically is achieved in the prior art by using a combination of a temperature sensor and a heater in a feedback loop tied into the printhead power source. For example, U.S. Patent 4,250,512 to Kattner et al. discloses a heating device for a mosaic recorder comprised of both a heater and a temperature sensor disposed in the immediate vicinity of ink ducts in a recording head. The heater and sensor function to monitor and regulate the temperature of a recording head during operation. Column 3, lines 7-24 describes how a temperature sensor, a thermistor, a heating element, and a resistor operate in unison to maintain the recording head at an optimum operational temperature to maximize printing efficiency. U.S. Patent No. 4,125,845 to Stevenson, Jr.
discloses an ink jet printhead temperature control circuit which uses a heater and a temperature sensing device to maintain a recording head temperature above the preset temperature level. An output from the temperature sensing device drives an electrical heater which regulates the recording head temperature. The temperature sensing device is a resistive element attached to the bottom side of the printhead by thick film techniques. U.S. Patent No. 4,704,620 to Ichihashi et al. discloses a temperature control system for an ink jet printer wherein the temperature of an ink jet printhead is controlled by a heater and a temperature sensor which collectively regulate heat transfer to maintain an ink jet printhead within an optimum stable discharge temperature range. The temperature control circuit, as shown in Figure 7 of the patent, utilizes an output from a comparator circuit and control signals from a signal processing circuit to regulate printhead temperature based on the output from the temperature sensor. U.S. Patent No. 4,791,435 to Smith et al. discloses a thermal ink jet printhead temperature control system which regulates the temperature of a printhead via a temperature sensing device and a heating component. The temperature sensing device, comprised of either a collection of transducers or a single thermistor closely estimates the temperature of the ink jet printhead and compensates for an unacceptable low printhead temperature by either cooling or heating the printhead as needed. U.S. Patent No. 4,686,544 to Ikeda et al. discloses a temperature control system for "drop-on-demandn ink jet printers wherein a heat generating electrode, positioned between layers of insulating and resistive material of a printhead substrate, controls the temperature of the printhead during operation, Column 4, lines 7-25, describes how an electrothermal transducer delivers the heat required to maintain the ink jet printhead at an optimum temperature level to maximize efficiency printing efficiently. U.S. Patent No. 4,636,812 to Bakewell, while disclosing a thermal printhead, also teaches using a heater and temperature sensor supported within a laminated layer nearthe marking resistors.
U.S. Patent No. 4,738,871 to Watanabe et al. discloses a heat-sensitive recording head which makes use of laser-made holes to control 2029S2~
the resistance of the heater resistors. These laser-made holes are also used to control the temperature which is directly related to the resistance. A
method for making the iaser holes is also provided.
U.S. Patent No. 4,772,866 to Willens discloses a device including a temperature sensor. The temperature sensor uses the semiconductor material (polysilicon) which is already part of the device.
U.S. Patent No. 4,449,033 to McClure et al. discloses a thermal printhead temperature sensing and control system. A sensor is made of a thermo-resistive material (Col. 4, lines 23-24) which runs parallel to the printhead leads. Means are provided for the temperature control circuitry for the printhead. The sensor can also sense a temperature change in a single printhead element (Col. 1, line 55). The sensor is situated above the printhead leads and separated from them by glass (Fig. 2, Numbers 10, 11).
The above references disclose various types of discrete temperature sensors which provide sensitivity for the particular system that they are used in. However, more precise temperature sensing and heater control may be required for certain print system depending upon printhead geometry, print speeds, and ambient operating temperature range. An optimum physical arrangement for a heater and sensor is to be in close proximity to the printhead. An optimum material from a manufacturing and economic standpoint is, for the temperature sensor to be formed from the same material as the resistor heating elements in the printhead. This goal, however, has not been achieved because the fabrication tolerances for the resistor are not sufficient for the purposes of forming sufficiently accurate thermometers on a plurality of printheads. In other words, it is heretofore not been possible to fabricate a plurality of printheads which may be required for a specific print system so that each temperature sensor for each printhead would be within a specific and consistent temperature tolerance range. A typical temperature coefficient of resistance of polysilicon is 1 x 10 -3/C and a typical resistance tolerance is + 5%. Thus, a thermistor formed near the resistor array would be inaccurate by as much as + 50C. Depending on the temperature control and printhead 202~2~
-performance, sensitivity to temperature for a specific system, a thermometer would have to obtain an accuracy of + 1 -5C.
Thus, heretofore, it has not been possible to form a thermistor in close proximity to the printhead and of the same material as the heaters or the printhead. According to the present invention, however, it has been found that the accuracy of a thermistor of the same material as the printhead heater elements can be improved so that its accuracy is within the desired temperature range (of 1-5C) by trimming the thermistor, or, by trimming an external resistor in series with the thermistor while holding the printhead at a desired temperature control set point. More particularly, the present invention is directed towards a thermal ink jet printhead including: a substrate support; an ink heating resistive layer disposed within said substrate comprising individual resistive elements in communication with an adjacent ink filled channel; and a second temperature sensitive resistive layer disposed within said substrate and proximate to said resistive layers, said temperature sensitive layer having an electrical connection to a temperature control circuit.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic perspective view of a bubble jet ink printing system incorporating the present invention.
Figure 2 is an enlarged schematic perspective view of the printhead of Figure 1.
Figure 3 is a cross-sectional side view of the printhead shown in Figure 2.
Figure 4 is a top plan view of the printhead shown in Figure 3.
Figure 5 is an alternate embodiment of the print head shown in Figure 4.
DESCRIPTION OF THE INVENTION
A typical carriage type bubble jet ink printing device 10 is shown in Fig. 1. A linear array of droplet producing bubble jet channels is housed in the printhead 11 of reciprocating carriage assembly 29. Droplets 12 are propelled to the recording medium 13 which is stepped by stepper motor 2029~27 16 a preselected distance in the di rection of arrow 14 each ti me the printing head traverses in one direction across the recording medium in the direction of arrow 15. The recording medium, such as paper, is stored on supply roll 17, and stepped onto roll 18 by stepper motor 16 by means well known in the art.
The printhead 11 is fixedly mounted on support base 19 which is adapted for reciprocal movement by any well known means such as by two parallel guide rails 20. The printhead and base comprise the reciprocating carriage assembly 29 which is moved back and forth across the recording medium in a direction parallel thereto and perpendicular to the direction in which the recording medium is stepped. The reciprocal movement of the printhead is achieved by a cable 21 and a pair of rotatable pulleys 22, one of which is powered by a reversible motor 23.
The current pulses are applied to the individual bubble generating resistors in each ink channel forming the array housed in the printing head 11 by conduits 24 from controller 25. The current pulses which produce the ink droplets are generated in response to digital data signals received by the controller through electrode 26. The ink channels are maintained full during operation via hose 27 from ink supply 28.
Fig 2 is an enlarged partially sectioned, perspective schematic of the carriage assembly 29 shown in Fig. 1. The printhead 11 includes substrate 41 containing the electrical leads 47 and bubble generating resistors 44 Printhead 11 also includes channel plate 49 having ink channels 49a and manifold 49b Although the channel plate 49 is shown in two separate pieces 31 and 32, the channel plate could be an integral structure. The ink channels 49a and ink manifold 49b are formed in the channel plate piece 31 having the nozzles 33 atthe end of each ink channel opposite the end connecting the manifold 49b. The ink supply hose 27 is connected to the manifold 49b via a passageway 34 in channel plate piece 31 shown in dashed line. Channel plate piece 32 is a flat member to cover channel plate piece 31 and together form the ink channel 49a and ink manifold 49b as they are appropriately aligned and fixedly mounted on substrate 41.
._ Referring now to Figures 3 and 4, Figure 3 shows (not to scale) a cross-sectional view of the substrate 41 of Figure 2. Substrate 41 is comprised of a crystal material such as silicon. A resistive thermistor layer 50, formed by standard thin film or integrated circuit fabrication methods upon the silicon substrate, is connected to an outside temperature control circuit 52 by electrode leads 54. The resistive heating elements 44 are connected by common electrodes 51 which are pulsed by signals sent along electrodes 47 to expel ink from nozzle 33.
According to a first aspect of the present invention, the resistive thermistor layer 50 is trimmed to a preselected resistance value by a laser trimming operation which is implemented at a time that the printhead is held at the set point temperature of interest. Since a laser trimming operation requires exacting tolerances, a simplified trimming operation can be performed by using the embodiment shown in Figure 5. There, thick film, or, alternately, thin film resistor element 58 has been formed on the surface of substrate 41, or adjacent substrate (not known) and connected in series with thermistor layer 50. The trimming operation is then performed on resistive element 58 until the desired resistance is achieved. For this embodiment, the total error in temperature reading from instability or temperature variation of the trimmed resistor will be in the order of 1C or less which is sufficiently accurate for a thermistor for thermal ink jet printing purposes. The external resistor to be trimmed may be formed as part of a hybrid circuit which also provides electrical interconnection to the printhead die. Alternatively, the resistor 58 to be trimmed may be added as a discrete chip resistor located on an adjacent substrate. For this example, the printhead may be packaged as a chip-on-board.
It will be appreciated that the above technique results in the elimination of resistance variability between a plurality of printheads being used in the same system, since all thermistors will operate in agreement with each other at the set temperature point of interest.
For the Figure 4 embodiment the nominal resistance of the polysilicon thermistor 50 is about 20KQ, and its temperature coefficient of resistance is about 1x10-3/C (i.e., a change of 1C corresponds to a 2~29527 thermistor resistance change of 20Q). Since the tolerance of the polysilicon resistor 44 will need to be kept within about + 5% from part to part and batch to batch, the thermistor will also be approximately this uniform (it may be slightly less uniform because of its high aspect ratio). In order to make the total resistance uniform at the set point, the trimmed resistance will need to vary over a range of about 2KQ, for example, from 3KQ (for devices in which the polysilicon is at its maximum resistance) to 5KQ (for devices in which the polysilicon is at its minimum resistance). According to resistor paste specifications, the stability of a laser trimmed resistor during its lifetime (under load and under heat) is typically 0.2%. A 5KQ trimmed resistor should be uniform to 10Q during its lifetime, corresponding to an apparent temperature change of 0.5C. The temperature coefficient of resistance of the thick film resistor is specified as 0 + 1x10-4/C. The temperature range of the substrate on which the external resistor 58 sits will almost certainly not exceed +20C during operation of the printer.
Th is wou Id correspond to a resistance change that wou Id not exceed + 1 OQ, corresponding to an apparent temperature change of +0.5C. Thus, the total temperature error due to changes in the externally trimmed resistor will be on the order of 1C or less.
While the invention has been described with reference to the structure disclosed, it is not confined to the specific details set forth. For example, while a carriage was shown with a single printhead, the invention may be used in other configurations such as a page width printer.
Claims (6)
1. A thermal ink jet printhead including:
a substrate support, a ink heating resistive layer disposed within said substrate comprising individual resistive elements in communication with an adjacent ink filled channel, a second temperature sensitive resistive layer disposed within said substrate and proximate to said resistive layers, said temperature sensitive layer having an electrical connection to a temperature control circuit.
a substrate support, a ink heating resistive layer disposed within said substrate comprising individual resistive elements in communication with an adjacent ink filled channel, a second temperature sensitive resistive layer disposed within said substrate and proximate to said resistive layers, said temperature sensitive layer having an electrical connection to a temperature control circuit.
2. The printhead of Claim 1 further including a second resistor formed on or adjacent to said substrate support and connected in series with said temperature sensitive resistive layer.
3. The printhead of Claim 1 wherein said second resistor is in discrete form.
4. The printhead of Claim 1 wherein said substrate is silicon and said ink heating resistive layer and said temperature sensitive resistive layers are polysilicon.
5. A method for maintaining accurate temperature measurements of a thermal ink jet printhead comprising the steps of, forming a plurality of resistive layers within a silicon substrate, forming a resistive thermistor layer adjacent to said heater resistor layers, and holding said printhead at a desired set point temperature and trimming said resistive thermistor layer to a desired resistance value.
6. The method of Claim 5 including forming or bonding a thick or thin film resistor in series with said thermistor layer, and trimming said thick or thin film resistor while holding said printhead at the set point temperature until the desired resistance is achieved.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US452178 | 1989-12-18 | ||
US07/452,178 US5075690A (en) | 1989-12-18 | 1989-12-18 | Temperature sensor for an ink jet printhead |
Publications (2)
Publication Number | Publication Date |
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CA2029527A1 CA2029527A1 (en) | 1991-06-19 |
CA2029527C true CA2029527C (en) | 1996-01-09 |
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Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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CA002029527A Expired - Lifetime CA2029527C (en) | 1989-12-18 | 1990-11-08 | Temperature sensor for an ink jet printhead |
Country Status (5)
Country | Link |
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US (1) | US5075690A (en) |
EP (1) | EP0434367B1 (en) |
JP (1) | JP3080319B2 (en) |
CA (1) | CA2029527C (en) |
DE (1) | DE69011640T2 (en) |
Families Citing this family (20)
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WO1991012966A1 (en) * | 1990-02-26 | 1991-09-05 | Canon Kabushiki Kaisha | Ink-jet recording head, substrate for said head, and ink-jet recording device |
US5585825A (en) * | 1994-11-25 | 1996-12-17 | Xerox Corporation | Ink jet printer having temperature sensor for replaceable printheads |
US5745130A (en) * | 1995-12-11 | 1998-04-28 | Xerox Corporation | System for sensing the temperature of a printhead in an ink jet printer |
US5881451A (en) * | 1996-06-21 | 1999-03-16 | Xerox Corporation | Sensing the temperature of a printhead in an ink jet printer |
US6505914B2 (en) * | 1997-10-02 | 2003-01-14 | Merckle Gmbh | Microactuator based on diamond |
US6278468B1 (en) | 1998-03-30 | 2001-08-21 | Xerox Corporation | Liquid ink printhead including a programmable temperature sensing device |
US6037831A (en) * | 1998-03-30 | 2000-03-14 | Xerox Corporation | Fusible link circuit including a preview feature |
US6276777B1 (en) | 1998-07-21 | 2001-08-21 | Hewlett-Packard Company | Variable maximum operating temperature for a printhead |
US6390585B1 (en) | 1998-07-21 | 2002-05-21 | Hewlett-Packard Company | Selectively warming a printhead for optimized performance |
US6322189B1 (en) | 1999-01-13 | 2001-11-27 | Hewlett-Packard Company | Multiple printhead apparatus with temperature control and method |
US6328407B1 (en) * | 1999-01-19 | 2001-12-11 | Xerox Corporation | Method and apparatus of prewarming a printhead using prepulses |
US6302507B1 (en) * | 1999-10-13 | 2001-10-16 | Hewlett-Packard Company | Method for controlling the over-energy applied to an inkjet print cartridge using dynamic pulse width adjustment based on printhead temperature |
DE10036345B4 (en) * | 2000-07-26 | 2005-07-07 | Francotyp-Postalia Ag & Co. Kg | Arrangement and method for data tracking for warm-up cycles of inkjet printheads |
US6565178B1 (en) * | 2001-10-29 | 2003-05-20 | Hewlett-Packard Development Company, L.P. | Temperature measurement device |
US6578942B1 (en) | 2002-04-10 | 2003-06-17 | Xerox Corporation | Liquid crystal sensing of thermal ink jet head temperature |
US6928380B2 (en) * | 2003-10-30 | 2005-08-09 | International Business Machines Corporation | Thermal measurements of electronic devices during operation |
US7572051B2 (en) * | 2004-11-15 | 2009-08-11 | Palo Alto Research Center Incorporated | Method and apparatus for calibrating a thermistor |
US7445315B2 (en) * | 2004-11-15 | 2008-11-04 | Palo Alto Research Center Incorporated | Thin film and thick film heater and control architecture for a liquid drop ejector |
KR101439849B1 (en) * | 2008-02-01 | 2014-09-17 | 삼성전자주식회사 | Apparatus for sensing temperature of an inkjet head |
US9862187B1 (en) | 2016-08-22 | 2018-01-09 | RF Printing Technologies LLC | Inkjet printhead temperature sensing at multiple locations |
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DE2659398A1 (en) * | 1976-12-29 | 1978-07-06 | Siemens Ag | HEATING DEVICE FOR WRITING HEADS IN INK MOSAIC WRITING DEVICES |
US4125845A (en) * | 1977-08-25 | 1978-11-14 | Silonics, Inc. | Ink jet print head pressure and temperature control circuits |
AU524439B2 (en) * | 1979-10-11 | 1982-09-16 | Matsushita Electric Industrial Co., Ltd. | Sputtered thin film thermistor |
JPS587361A (en) * | 1981-07-03 | 1983-01-17 | Canon Inc | Liquid jet recording head |
JPS58220757A (en) * | 1982-06-18 | 1983-12-22 | Canon Inc | Liquid jet recording head |
US4449033A (en) * | 1982-12-27 | 1984-05-15 | International Business Machines Corporation | Thermal print head temperature sensing and control |
JPS60116451A (en) * | 1983-11-30 | 1985-06-22 | Canon Inc | Liquid jet recording head |
US4532530A (en) * | 1984-03-09 | 1985-07-30 | Xerox Corporation | Bubble jet printing device |
JPS61122557A (en) * | 1984-11-20 | 1986-06-10 | Omron Tateisi Electronics Co | Trimming method of resistance value of thick film type sensor |
EP0211331A3 (en) * | 1985-08-02 | 1989-10-25 | Hitachi, Ltd. | Heat-sensitive recording head and method of manufacturing same |
JPH0630929B2 (en) * | 1985-09-04 | 1994-04-27 | キヤノン株式会社 | Inkjet printer |
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JP2611981B2 (en) * | 1987-02-04 | 1997-05-21 | キヤノン株式会社 | Substrate for ink jet recording head and ink jet recording head |
JPS645863A (en) * | 1987-06-30 | 1989-01-10 | Nec Corp | Driver lsi of led recording head |
US4791435A (en) * | 1987-07-23 | 1988-12-13 | Hewlett-Packard Company | Thermal inkjet printhead temperature control |
US4881057A (en) * | 1987-09-28 | 1989-11-14 | Ranco Incorporated | Temperature sensing apparatus and method of making same |
US4899180A (en) * | 1988-04-29 | 1990-02-06 | Xerox Corporation | On chip heater element and temperature sensor |
US4910528A (en) * | 1989-01-10 | 1990-03-20 | Hewlett-Packard Company | Ink jet printer thermal control system |
-
1989
- 1989-12-18 US US07/452,178 patent/US5075690A/en not_active Expired - Lifetime
-
1990
- 1990-11-08 CA CA002029527A patent/CA2029527C/en not_active Expired - Lifetime
- 1990-11-30 JP JP02341205A patent/JP3080319B2/en not_active Expired - Lifetime
- 1990-12-18 EP EP90313852A patent/EP0434367B1/en not_active Expired - Lifetime
- 1990-12-18 DE DE69011640T patent/DE69011640T2/en not_active Expired - Lifetime
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US5075690A (en) | 1991-12-24 |
JPH03190745A (en) | 1991-08-20 |
DE69011640T2 (en) | 1995-03-16 |
CA2029527A1 (en) | 1991-06-19 |
DE69011640D1 (en) | 1994-09-22 |
EP0434367B1 (en) | 1994-08-17 |
JP3080319B2 (en) | 2000-08-28 |
EP0434367A3 (en) | 1991-08-21 |
EP0434367A2 (en) | 1991-06-26 |
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