JP2004050636A - Substrate for inkjet head, inkjet head, and inkjet recorder employing inkjet head - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a substrate for an inkjet head for use in an inkjet recorder in which a rank heater having a resistance being measured in order to control the pulse width being applied to a heater is protected against electrostatic breakdown. <P>SOLUTION: A means for protecting a rank heater 26 against electrostatic discharge is provided. A dummy MOS connected in parallel with the rank heater 26 is preferably employed as the protective means. Furthermore, a protective element, e.g. a protective diode, may be provided in the wiring between the rank heater 26 and a pad 22 for the rank heater. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention includes an inkjet head substrate used for an inkjet head that performs recording by ejecting ink droplets from an ejection port, an inkjet head having such an inkjet head substrate, and an inkjet head having such an inkjet head. The present invention relates to an inkjet recording apparatus.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there has been known an ink jet recording method for performing recording on a recording medium (in many cases, paper) by discharging and flying ink droplets from a discharge port. This inkjet recording method is a non-impact type recording method, and has features such as low noise, direct recording on plain paper, and easy recording of color images by using multicolor inks. In recent years, it is rapidly spreading. Above all, there is known a recording method in which thermal energy is added to ink in response to a recording signal to foam the ink, and the ink is ejected from an ejection port and flies by the acting force at this time. This method has an advantage that high-density multi-nozzles can be easily formed, and a high-resolution and high-speed nozzle can be easily obtained.
[0003]
In an ink jet head used for this recording method, in many cases, a large number of ejection ports for ejecting ink are provided, and a liquid flow path communicating with the ejection port provided for each ejection port is provided in each liquid flow path. A common liquid chamber for stably supplying ink is provided. This ink jet head uses thermal energy generated by energizing a heater through a driver to discharge ink sent through a liquid flow path from a discharge port to perform recording.
[0004]
Such an inkjet head is configured by, for example, combining a substrate for an inkjet head with a top plate in which a liquid flow path, a liquid chamber, a discharge port, and the like are formed. The inkjet head substrate includes a heater (heating element) for generating thermal energy for discharging ink, a driver for driving the heater, a logic circuit for controlling the driver, an inkjet head and an inkjet printing apparatus. And a pad portion for electrically connecting to the power supply. The heaters are formed as many as the number of discharge ports, and therefore, the drivers are formed according to the number of discharge ports. Such an ink jet head substrate is monolithically formed of a silicon semiconductor substrate based on a semiconductor device manufacturing technique.
[0005]
Incidentally, the heater is constituted by a thin film resistor deposited on the substrate for the ink jet head. The electric resistance value of the heater can change depending on the deposition conditions of the thin film resistor and the like. From the viewpoint of stabilizing the ink ejection amount and achieving stable printing, it is necessary to estimate the variation in the resistance value of the heater and control the width of the pulse applied to the heater based on the estimated value. . Therefore, the inkjet head substrate is provided with a heater of the same size as the discharge heater, which is called a rank heater. By detecting the resistance value of this rank heater from the outside of the inkjet head substrate, the discharge is performed. It was possible to estimate the fluctuation of the resistance value of the heater.
[0006]
[Problems to be solved by the invention]
As described above, in the inkjet head substrate, integration of driver circuits, logic circuits, and the like is progressing, but the inkjet head incorporating such an inkjet head substrate is assumed to be replaced by a user. In this case, the user can directly touch at the time of replacement or the like. Therefore, when an electrostatic discharge occurs during handling by a user or the like, the electrostatic component is applied to the inkjet head substrate through a pad portion or wiring of the inkjet head, and a portion of the inkjet head substrate that is weak to static electricity is applied. There is a problem that the device is destroyed and the device is destroyed.
[0007]
Since a functional element such as a driver or a logic circuit is electrically connected to the discharge heater, electrostatic discharge is not directly applied to the discharge heater. However, since the rank heater is provided only for detecting the resistance value from the outside, the rank heater is directly connected to the input pad of the inkjet head substrate, and is configured to directly apply the electrostatic discharge. Therefore, the rank heater has a problem that it is more susceptible to electrostatic breakdown than the discharge heater.
[0008]
Therefore, an object of the present invention is to provide an inkjet head substrate having improved resistance to electrostatic breakdown, an inkjet head having such an inkjet head substrate, and an inkjet recording apparatus using such an inkjet head. It is in.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention is characterized in that a dummy MOS is electrically connected to a rank heater section of a substrate for an ink jet recording head to improve the resistance against electrostatic breakdown. Further, by providing a protection element between the rank heater and the pad, it is possible to further improve the resistance against electrostatic breakdown.
[0010]
That is, the inkjet head substrate of the present invention is used in an inkjet recording apparatus that ejects ink using thermal energy, and includes a plurality of heaters for ejecting ink, and a plurality of drivers for driving the plurality of heaters. A logic circuit for controlling a plurality of drivers, an input / output pad for transferring signals between the printing apparatus body and the logic circuit, and a rank heater for measuring the resistance value of the heater. In the inkjet head substrate formed above, protection means for protecting the rank heater from electrostatic discharge is provided.
[0011]
In the present invention, as the protection means, a dummy MOS provided in parallel with the rank heater or a protection element connected to the wiring between the rank heater and the pad for the rank heater can be used.
[0012]
The inkjet head of the present invention includes the above-described inkjet head substrate of the present invention, a liquid passage associated with the heater combined with the inkjet head substrate, and a member for forming an ink ejection port forming one end of the liquid passage, And is detachable from the ink jet recording apparatus.
[0013]
According to another aspect of the invention, there is provided an inkjet recording apparatus including: the inkjet head according to the aspect of the invention; and a unit configured to relatively convey a print medium with respect to the inkjet head.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, a preferred embodiment of the present invention will be described with reference to the drawings.
[0015]
The term “on the substrate” used herein refers not only to the top of the element substrate but also to the surface of the element substrate and the inside of the element substrate near the surface. Further, the term “built-in” in the present invention is not a word indicating that each separate element is simply arranged on a substrate, but each element is formed by a semiconductor circuit manufacturing process or the like. It shows that it is integrally formed and manufactured on a substrate.
[0016]
FIG. 1 is a plan view showing an inkjet head substrate according to one embodiment of the present invention.
[0017]
The inkjet head substrate 21 is formed (built-in) on a silicon semiconductor substrate or the like by using a semiconductor device manufacturing technique, and has a substantially rectangular shape as shown in FIG. The ink supply port 20 is formed as a through hole extending in the longitudinal direction. A plurality of heaters 24 are provided along both sides of the ink supply port 20. The heater 24 heats and bubbling the liquid (ink) supplied from the back surface side of the ink jet head substrate 21 through the ink supply port 20, and discharge ports provided to face the heater 24. (Not shown in FIG. 1) for discharging ink droplets. On the opposite side of the ink supply port 20 across the heater 24, a driver unit 25 is provided. The driver unit 25 includes a driver for driving each heater 24 and the like. The driver is typically provided for each heater 24, and includes a switch transistor and the like. Further, the inkjet head substrate 21 is provided with a logic circuit portion 23 and a pad portion for supplying a power source and a signal from the recording device main body side to the inkjet head substrate. The pad section includes a plurality of pads 22 and is used to route wiring outside the substrate by using an electrical connection means such as wire bonding, and to electrically connect the inkjet head and the inkjet recording apparatus. The logic circuit unit 23 includes a logic circuit that controls on / off of each transistor in the driver unit 25 based on a signal when a signal is given from the printing apparatus main body side via the pad 22. .
[0018]
Further, the inkjet head substrate 21 is provided with a rank heater 26 for monitoring the resistance value of the heater 24. The rank heater 26 is formed in the same manner as the heater 24, but can measure the resistance value from the outside via the input / output pad 22. The resistance value of each heater 24 is estimated by measuring the resistance value of the rank heater 26 from the printing apparatus main body side, and based on the estimated value, the width of the pulse applied to the heater 24 is controlled, and It is designed to be stable.
[0019]
In the inkjet head having such an inkjet head substrate 21, when a signal is input to the inkjet head substrate 21 via the pad 22, the logic circuit in the logic circuit unit 23 converts the transistor in the driver unit 25, that is, the driver Is controlled by turning on / off. Then, when the heater 24 in the portion where the transistor is turned on is energized, the heater 24 is heated, the ink (liquid) on the heater 24 is heated, and bubbles are rapidly generated in the ink, so that the ink is ejected from the discharge port. It is.
[0020]
Next, the rank heater in the inkjet head substrate of the present embodiment will be described.
[0021]
FIG. 2 is an equivalent circuit diagram when a general rank heater is directly connected from the input / output pad 22. The rank heater 11, unlike a heater that actually generates discharge energy, is only an element for monitoring a heater resistance value, and is not connected to a functional element such as a logic circuit. Conventionally, the rank heater 11 has been used with a very simple connection in which one end is connected to one input pad 22 and the other end is grounded. In this case, when the electrostatic discharge is applied to the inkjet head, a large current i due to the electrostatic discharge flows from the contact portion of the inkjet head through the pad 22 of the inkjet head substrate 21 into the inkjet head substrate 21. The large current i that has flowed in here is all applied to the rank heater element itself, and as a result, the element may be destroyed.
[0022]
Therefore, in the inkjet head substrate 21 of the present invention, as shown in FIG. 3, a dummy MOS 32 which is a MOS (metal-oxide-semiconductor) transistor is connected in parallel with the rank heater 26. The dummy MOS 32 is typically an N-channel MOS transistor whose gate and source are grounded. In a normal operation state in which static electricity is not applied to the input pad 22, the dummy MOS 32 is in a cut-off state, and when the resistance value of the rank heater 26 is measured through the input pad 22, The resistance value can be measured accurately. On the other hand, when the electrostatic discharge is applied to the input pad 22, the current i flows to the ground via the dummy MOS 32, thereby preventing an excessive current from flowing to the rank heater 26. By adopting such a configuration, it is possible to adopt a configuration in which the charge applied to the input pad 22 for the rank heater 26 is actively dispersed to the ground and released without increasing the substrate size.
[0023]
Further, in order to improve the resistance against static electricity, further protection means can be arranged on the input pad 22 side. 4A is obtained by adding a protection element 33, which is a protection diode, to the input pad 22 side (nearer) than the rank heater 26 and the dummy MOS 32 in the configuration shown in FIG. In this case, assuming that the power supply in the ink jet head substrate is a positive power supply, a first protection diode as a protection element 33 is provided between the wiring extending from the input pad 22 to the rank heater 26 and the power supply line so that the cathode is on the power supply line side. In addition, a second protection diode is inserted as a protection element 33 between the wiring from the input pad 22 to the rank heater 26 and the ground so that the anode is on the ground side. With this configuration, the large current i due to the electrostatic discharge flows to the power supply line or the ground through the protection element 33, and the resistance to static electricity is further improved. It is desirable that the protection diode is arranged near the input pad 22, but from the viewpoint of the arrangement and the like, it is sufficient that the protection diode is located closer to the pad than the intermediate position of the wiring between the input pad and the rank heater.
[0024]
Specifically, in the state shown in FIG. 2, the rank heater element destruction event that occurred at a static electricity applied voltage of 2 kV in the contact discharge (discharge resistance 330Ω, discharge capacitor 150 pF) uses the form of FIG. Did not occur unless the applied voltage was 5 kV or more.
[0025]
The logic circuit section 23 is provided on the inkjet head substrate 21 as described above. The protection diode used as the protection element 33 is a protection diode connected to a logic circuit in the logic circuit section 23. It is preferable to use one having the same size as. The logic circuit in the ink jet head substrate is generally a CMOS circuit, and usually includes this kind of protection diode.
[0026]
It is also conceivable to remove the dummy MOS from the configuration of FIG. FIG. 4B shows such a configuration having no dummy MOS. However, the resistance of the rank heater 26 to static electricity is sufficiently improved as compared with the conventional one.
[0027]
Further, as shown in FIG. 5A, in the configuration shown in FIG. 4A, when the protection element 33 is arranged near the input pad, the resistance to static electricity is further improved. Specifically, the protection element 33 is connected to the wiring between the input pad 22 and the rank heater 26 at a position closer to the input pad 22 than the middle point of the wiring.
[0028]
It is also conceivable to remove the dummy MOS from the configuration of FIG. FIG. 5B shows such a configuration having no dummy MOS, but the resistance of the rank heater 26 to static electricity is sufficiently improved as compared with the conventional one.
[0029]
By providing the protection element 33 as described above, even if the resistance of the rank heater itself is improved, if the wiring width (part a in FIG. 6A) reaching the protection element 33 is small, the instantaneous It is also conceivable that the wiring breakage occurs due to the large current i. Therefore, by making the wiring width from the input pad to the protection element larger than the wiring width from the protection element 33 to the rank heater as shown in FIG. It is conceivable to adopt a configuration that can be used. With this configuration, it is possible to further increase the resistance to static electricity.
[0030]
In the configuration shown in FIG. 6A, it is conceivable to remove the dummy MOS. FIG. 6B shows such a configuration having no dummy MOS. However, the resistance of the rank heater 26 to static electricity is sufficiently improved as compared with the conventional one.
[0031]
Incidentally, the inkjet head substrate 21 is manufactured using the semiconductor device manufacturing technology as described above, and the logic circuit unit 23 and the driver unit 25 have substantially the same structure as that of the semiconductor integrated circuit. Therefore, the inkjet head substrate 21 uses a multilayer wiring structure. Here, if there is a wiring layer that intersects the wiring from the input pad 22 to the protection element 33, a step is formed at the intersection. When a large current i due to electrostatic discharge passes through such a step, the wiring may be disconnected at the step at the wiring intersection. Therefore, as shown in FIG. 7A, it is preferable that the wiring portion from the pad 22 to the protection element 33 does not have a step due to wiring crossing. Can be further improved. In the configuration of FIG. 7A, it is conceivable to remove the dummy MOS. FIG. 7B shows such a configuration having no dummy MOS. However, the resistance of the rank heater 26 to static electricity is sufficiently improved as compared with the conventional one.
[0032]
Next, a schematic configuration of an inkjet head of the present invention using the inkjet head substrate 21 as described above will be described with reference to FIG. As described above, in this embodiment, the heaters 24 are provided on both sides of the ink supply port 20, but in FIG. 8, for simplicity of description, the heater 24 on one side of the ink supply port 20 and the corresponding heater 24 are provided. Only the discharge ports 40 to be operated are displayed.
[0033]
As described above, on the inkjet head substrate 21, a plurality of heaters 24 for generating heat by receiving an electric signal and discharging ink from the discharge ports 40 by bubbles generated by the heat are provided in a row. It is arranged in. Flow paths 41 for supplying ink to the ejection ports 40 provided at positions facing the heaters 24 are provided corresponding to the respective ejection ports 40. These discharge ports 40 are formed in the orifice plate 101. By connecting the orifice plate 101 to the above-described substrate 21 for an ink jet head, a common liquid chamber that communicates with the ink supply port 20 and supplies ink to each flow path 41 is provided.
[0034]
FIG. 9 shows the appearance of an example of this ink jet head. On the TAB tape 200, an electrical connection portion 201 for connection to the inkjet head substrate 21 is provided, and on one end side of the TAB tape 200, a contact pad portion 204 used for connection to a recording device is formed. The ink jet head substrate 21 of the present invention is located below the orifice plate 101. After the flow path 41 is formed on the ink jet head substrate 21 with a dry film or the like, the orifice plate 101 is attached, and the TAB tape 200 is attached thereto. It is attached to the attached ink tank 203. Thereafter, bonding is performed, and the electrical connection portion 201 of the TAB tape 200 is sealed with a sealing material, thereby completing an ink jet head.
[0035]
Since this ink jet head is removable, it may come into contact with human hands. Therefore, it can be said that there is a possibility that the electrostatic discharge is applied from the contact pad portion 204. If static electricity is applied to the contact pad portion, the applied static electricity is discharged to the inkjet head substrate 21 via the TAB tape 200.
[0036]
FIG. 10 is a schematic view of an ink jet recording apparatus IJRA to which the ink jet head of the present invention is applied.
[0037]
The carriage HC, which engages with the groove 5004 of the lead screw 5005 that rotates through the driving force transmission gears 5011 and 5009 in conjunction with the forward and reverse rotations of the drive motor 5013, has an inkjet head detachably mounted. It has a pin (not shown) and is reciprocated in the directions of arrows a and b. Reference numeral 5002 denotes a paper pressing plate, which presses a print medium, typically paper, against a platen 5000, which is print medium transport means, in the carriage movement direction. Reference numerals 5007 and 5008 denote home position detecting means for confirming the presence of the carriage lever 5006 in this area by photocouplers and switching the rotation direction of the motor 5013. Reference numeral 5016 denotes a member that supports a cap member 5022 that caps the front surface of the ink jet head. Reference numeral 5015 denotes suction means that suctions the inside of the cap, and performs suction recovery of the ink jet head through an opening 5023 in the cap. Reference numeral 5017 denotes a cleaning blade. Reference numeral 5019 denotes a member which allows the blade to move in the front-rear direction. These members are supported by a main body support plate 5018. It goes without saying that the blade is not limited to this form and a known cleaning blade can be applied to the present embodiment. Reference numeral 5012 denotes a lever for starting suction for suction recovery, which moves with the movement of the cam 5020 which engages with the carriage, and which controls the movement of the drive force from the drive motor by a known transmission means such as clutch switching. Is done.
[0038]
The capping, cleaning, and suction recovery are configured so that when the carriage comes to the home position side area, desired operations can be performed at the corresponding positions by the action of the lead screw 5005. Any operation can be applied to this example as long as the operation is performed. Each of the above-described configurations is an excellent invention when viewed alone or in combination, and shows preferred configuration examples for the present invention.
[0039]
The present apparatus is provided with a signal supply unit for supplying a drive signal for driving the heating element and other signals to the inkjet head (substrate for the inkjet head).
[0040]
【The invention's effect】
As described above, the present invention has an effect that by providing the protection means for protecting the rank heater from electrostatic discharge, the resistance to electrostatic breakdown can be improved without increasing the size of the substrate.
[Brief description of the drawings]
FIG. 1 is a plan view showing a configuration of an inkjet head substrate according to an embodiment of the present invention.
FIG. 2 is a circuit diagram of a general rank heater and a diagram showing a destruction mode by electrostatic discharge.
FIG. 3 is an equivalent circuit diagram showing a rank heater in the inkjet head substrate according to one embodiment of the present invention.
FIGS. 4A and 4B are equivalent circuit diagrams illustrating another example of the diode sensor in the inkjet head substrate according to the embodiment of the present invention; FIGS.
FIGS. 5A and 5B are equivalent circuit diagrams illustrating another example of the diode sensor in the inkjet head substrate according to the embodiment of the present invention; FIGS.
FIGS. 6A and 6B are equivalent circuit diagrams illustrating another example of the diode sensor in the inkjet head substrate according to the embodiment of the present invention; FIGS.
FIGS. 7A and 7B are equivalent circuit diagrams illustrating another example of the diode sensor in the inkjet head substrate according to the embodiment of the present invention; FIG.
8 is a schematic configuration diagram of an inkjet head using the inkjet head substrate shown in FIG.
9 is an external view of the inkjet head shown in FIG.
FIG. 10 is a perspective view showing a configuration example of an ink jet recording apparatus using the ink jet head shown in FIG.
[Explanation of symbols]
11, 26 rank heater 21 ink jet head substrate 22 pad 23 logic circuit unit 24 heater 25 driver unit 32 dummy MOS
33 Protection element 101 Orifice plate 200 TAB tape 201 Electrical connection part 203 Ink tank 204 Contact pad part

Claims (12)

Used in an inkjet recording apparatus that ejects ink using thermal energy, controls a plurality of heaters for ejecting the ink, a plurality of drivers for driving the plurality of heaters, and the plurality of drivers. Logic circuit, an input / output pad for transferring signals between the printing apparatus body and the logic circuit, and a rank heater for measuring the resistance value of the heater are formed on the same substrate. In the inkjet head substrate,
A substrate for an ink jet head, comprising a protection means for protecting the rank heater from electrostatic discharge. The substrate according to claim 1, wherein the protection unit includes a dummy MOS provided in parallel with the rank heater. 2. The substrate according to claim 1, wherein the dummy MOS is an N-channel MOS transistor. 4. The inkjet head according to claim 1, wherein the protection unit includes a protection element connected to a wiring between the rank heater and a pad for the rank heater. 5. Substrate. The inkjet head substrate according to claim 4, wherein the protection element is arranged on the pad side from an intermediate position of a wiring between the rank heater pad and the rank heater. The substrate for an inkjet head according to claim 4, wherein a wiring width from the rank heater pad to the protection element is larger than a wiring width from the protection element to the rank heater. The inkjet head substrate according to claim 4, wherein the protection element is arranged closer to the rank heater pad than a wiring intersection with another wiring layer in the inkjet head substrate. The ink jet head according to claim 4, wherein the logic circuit section further includes a protection element, and the protection element connected to the substrate temperature detection element and the protection element connected to the logic circuit have the same size. Substrate. The inkjet head substrate according to any one of claims 4 to 8, wherein the protection element is a protection diode. 10. An ink jet head substrate according to claim 1, and a liquid passage associated with the heater and an ink discharge port forming one end of the liquid passage combined with the ink jet head substrate. And an ink jet recording head, which is detachable from the ink jet recording apparatus. An ink jet recording apparatus comprising: the ink jet head according to claim 10; and means for conveying a print medium relative to the ink jet head. The ink jet recording apparatus according to claim 11, further comprising a carriage that detachably supports the ink jet head and scans the print medium.

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