JP2009269238A - Liquid injection head, liquid injection device, and control method for liquid injection head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid ejecting head, a liquid ejecting apparatus, and a method for controlling the liquid ejecting head which do not cause damage to an actuator unit.
A liquid ejecting head includes a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting liquid is formed, and a region of the flow path forming substrate facing the pressure generating chamber. Signal processing for processing the drive signal output from the control unit 200 that generates and outputs a drive signal S1 for driving the actuator unit and the actuator unit having at least a pressure generating element, and sends the processed signal to the pressure generating unit And a low-pass filter 203 for removing a resonance frequency component of the diaphragm and the pressure generating means included in the drive signal.
[Selection] Figure 3

Description

  The present invention relates to a liquid ejecting head, a liquid ejecting apparatus, and a method for controlling the liquid ejecting head.

  Some liquid ejecting apparatuses use an actuator unit as liquid pressurizing means. For example, a liquid ejecting apparatus described in Patent Document 1 includes a liquid flow path serving as a liquid flow path, a liquid pressurizing chamber adjacent to the liquid flow path and having a liquid ejection port for ejecting liquid, and a liquid In a liquid ejecting apparatus including a liquid ejecting body adjacent to a pressurizing chamber and having at least a liquid pressurizing unit that is driven by voltage or current, the frequency component that the voltage or current has is a liquid flow path and the liquid pressurizing chamber. At least one resonance frequency of the liquid jet main body in a state where the liquid is filled.

JP 2001-088298 A (Claim 1, paragraph 0033, etc.)

  In the liquid ejecting apparatus, the frequency component of the voltage or current includes the resonance frequency component, so that the actuator unit can be driven to a large displacement. However, when the drive signal is formed so as to include the resonance frequency component and applied to the actuator unit as described above, vibration due to resonance becomes too large, and the pressure generating element constituting the actuator unit may be damaged. Even if the drive signal is not configured to include a resonance frequency component, the drive signal may include a resonance frequency as noise. In this case, the actuator unit may be damaged due to resonance. In particular, when the actuator section is a pressure generating element such as a piezoelectric element or the pressure generating element is provided with a diaphragm, this problem becomes significant.

  Accordingly, an object of the present invention is to solve the above-described problems of the prior art, and to provide a liquid ejecting head, a liquid ejecting apparatus, and a method for controlling the liquid ejecting head that do not damage the actuator unit. And

The liquid ejecting head according to the present invention includes a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting liquid is formed, and at least pressure generation in a region facing the pressure generating chamber of the flow path forming substrate. An actuator unit having an element, and a signal processing unit that processes the drive signal output from the control unit that generates and outputs a drive signal for driving the actuator unit and sends the drive signal to the actuator unit, and A low-pass filter for removing a resonance frequency component of the actuator unit included in the drive signal is provided in the signal processing unit.
In the liquid ejecting head according to the aspect of the invention, the actuator unit can be prevented from being damaged by providing the low-pass filter for removing the resonance frequency component of the actuator unit included in the drive signal.

  The signal processing unit is provided with a switching element connected in series to the actuator unit for each actuator unit, and between the switching element and the input unit of the input signal of the signal processing unit. The low-pass filter is preferably provided. By being provided at this position, the resonance frequency component of the drive signal applied to the actuator section can be removed by one low-pass filter.

  Here, the cutoff frequency of the low-pass filter is preferably 0.14 MHz or less. When the cut-off frequency is 0.14 MHz or less, damage to the actuator unit due to resonance can be prevented when a drive signal is applied to the actuator unit of the liquid jet head in each state after the manufacturing process.

  In a preferred aspect of the present invention, the actuator unit is a piezoelectric element including a diaphragm and a lower electrode, a piezoelectric layer, and an upper electrode provided in a region facing the pressure generation chamber of the diaphragm. Is mentioned.

  In the liquid ejecting apparatus of the present invention, a control unit that generates and outputs a drive signal for driving the actuator unit by the drive signal generation unit, and a pressure generation chamber that communicates with a nozzle opening that ejects the liquid are formed. A flow path forming substrate, the actuator unit having at least a pressure generating element in a region facing the pressure generating chamber of the flow path forming substrate, and a drive signal from the control unit are processed and sent to the actuator unit A liquid jet head having a signal processing unit, and a low-pass filter for removing a resonance frequency component of the actuator unit included in the driving signal is provided between the driving signal generating unit and the signal processing unit. It is characterized by. In the liquid ejecting apparatus according to the aspect of the invention, the low-pass filter that removes the resonance frequency component of the actuator unit included in the drive signal is provided, thereby removing the resonance frequency component that causes damage to the actuator unit. Therefore, the actuator portion can be prevented from being damaged.

  The method for controlling a liquid ejecting head according to the present invention includes a flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting liquid is formed, and a region of the flow path forming substrate facing the pressure generating chamber. In a method for controlling a liquid jet head, comprising: an actuator unit having at least a pressure generating element; and a signal processing unit that processes a drive signal output from the control unit to drive the actuator unit and sends the signal to the actuator unit The resonance frequency component of the actuator unit included in the drive signal is removed by a low-pass filter provided in the signal processing unit. Thereby, damage of an actuator part can be prevented.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an exploded perspective view showing a schematic configuration of an ink jet recording head which is an example of a liquid ejecting head according to the present embodiment, FIG. 2A is a plan view of FIG. 1, and FIG. It is an AA 'line sectional view of a).

In this embodiment, the flow path forming substrate 10 is formed of a silicon single crystal substrate having a (110) crystal plane orientation. An elastic film 50 made of silicon dioxide is previously formed on one surface of the flow path forming substrate 10 by thermal oxidation, and an insulator film 55 made of zirconium oxide (ZrO ₂ ) or the like is formed on the elastic film 50. Yes. In addition, pressure generation chambers 12 partitioned by a plurality of partition walls 11 are arranged in parallel in the width direction (short direction) on the other surface of the flow path forming substrate 10 by anisotropic etching from the other surface side. Has been. A communication portion 13 is formed in a region on the outer side in the longitudinal direction of the pressure generation chamber 12 in each row, and the communication portion 13 and each pressure generation chamber 12 are connected to an ink supply path 14 and a communication path provided for each pressure generation chamber 12. 15 to communicate with each other. That is, on the flow path forming substrate 10, a pressure generation chamber 12, a communication portion 13, an ink supply path 14, and a communication path 15 are formed as liquid flow paths. The communication portion 13 communicates with a reservoir portion 31 of the protective substrate 30 described later and constitutes a part of the reservoir 100 that becomes a common ink chamber for each row of the pressure generating chambers 12.

  On the opening surface side (the other surface side) of the flow path forming substrate 10, there is a nozzle plate 20 in which a nozzle opening 21 communicating with the vicinity of the end of each pressure generating chamber 12 on the side opposite to the ink supply path 14 is formed. It is fixed by an adhesive or a heat welding film.

  On the insulator film 55, a lower electrode 60, a piezoelectric layer 70 made of lead zirconate titanate (PZT) or the like, which is an example of a piezoelectric film, and an upper electrode 80 are laminated to form a piezoelectric element 300. Is configured. Here, the piezoelectric element 300 refers to a portion including the lower electrode 60, the piezoelectric layer 70, and the upper electrode 80. The piezoelectric element 300 functions as pressure generating means for causing a pressure change in the ink (liquid) in the pressure generating chamber 12. The piezoelectric layer 70 is made of a piezoelectric material formed on the lower electrode 60 and having an electromechanical conversion action, particularly a ferroelectric material having a perovskite structure among the piezoelectric materials.

  In the present embodiment, the lower electrode 60 of the piezoelectric element 300 is used as a common electrode, the upper electrode 80 is used as an individual electrode of the piezoelectric element 300, and driving from the control unit 200 described later between the upper electrode 80 and the lower electrode 60 is performed. A voltage based on the signal S1 is applied to drive the piezoelectric layer 70. By driving the piezoelectric layer 70, the elastic film 50 and the insulator film 55 on the pressure generating chamber 12 vibrate. That is, in the present embodiment, these elastic film 50 and insulator film 55 function as a diaphragm. In this embodiment, the elastic film 50 and the insulator film 55 function as a diaphragm, but only one of the elastic film 50 and the insulator film 55 may be provided as a diaphragm. Further, the lower electrode 60 constituting the piezoelectric element 300 may function as a diaphragm without providing the elastic film 50 and the insulator film 55. In any case, an actuator unit including at least the piezoelectric element 300 as a pressure generating element is used.

  Each upper electrode 80 which is an individual electrode of the piezoelectric element 300 is a lead made of, for example, gold (Au) or the like, which is drawn from the vicinity of the end on the ink supply path 14 side and extends to the insulator film 55. An electrode 90 is connected.

  On the flow path forming substrate 10 on which such a piezoelectric element 300 is formed, that is, on the lower electrode 60, the insulator film 55, and the lead electrode 90, a protection having a reservoir portion 31 constituting at least a part of the reservoir 100. The substrate 30 is bonded via an adhesive 35. In the present embodiment, the reservoir portion 31 is formed through the protective substrate 30 in the thickness direction and across the width direction of the pressure generation chamber 12. As described above, the communication portion 13 of the flow path forming substrate 10. The reservoir 100 is configured as a common ink chamber for the pressure generation chambers 12. Alternatively, the communication portion 13 of the flow path forming substrate 10 may be divided into a plurality of pressure generation chambers 12 and only the reservoir portion 31 may be used as the reservoir. Further, for example, only the pressure generation chamber 12 is provided in the flow path forming substrate 10, and a reservoir and a member interposed between the flow path forming substrate 10 and the protective substrate 30 (for example, the elastic film 50, the insulator film 55, etc.) An ink supply path 14 that communicates with each pressure generating chamber 12 may be provided.

  The protective substrate 30 is provided with a piezoelectric element holding portion 32 having a space that does not hinder the movement of the piezoelectric element 300 in a region facing the piezoelectric element 300. The protective substrate 30 is provided with a through hole 33 that penetrates the protective substrate 30 in the thickness direction. The vicinity of the end portion of the lead electrode 90 drawn from each piezoelectric element 300 is provided so as to be exposed in the through hole 33.

  A driving circuit 120 that functions as a signal processing unit is fixed on the protective substrate 30. The drive circuit 120 receives various signals from a control unit described later, processes these signals, and applies them to the piezoelectric element 300. As the drive circuit 120, for example, a circuit board, a semiconductor integrated circuit (IC), or the like can be used. The drive circuit 120 and the lead electrode 90 are electrically connected via a connection wiring 121 made of a conductive wire such as a bonding wire inserted through the through hole 33.

  As the protective substrate 30, it is preferable to use a material substantially the same as the coefficient of thermal expansion of the flow path forming substrate 10, for example, glass, a ceramic material, or the like. In this embodiment, a silicon single crystal substrate having the same surface orientation (110) as the flow path forming substrate 10 is used.

  A compliance substrate 40 including a sealing film 41 and a fixing plate 42 is bonded onto the protective substrate 30. Here, the sealing film 41 is made of a material having low rigidity and flexibility, for example, a polyphenylene sulfide (PPS) film, and one surface of the reservoir portion 31 is sealed by the sealing film 41. The fixing plate 42 is made of a hard material such as metal, for example, stainless steel (SUS). Since the region of the fixing plate 42 facing the reservoir 100 is an opening 43 that is completely removed in the thickness direction, one surface of the reservoir 100 is sealed only with a flexible sealing film 41. Has been.

  The recording head shown in FIGS. 1 and 2 is configured such that the piezoelectric element 300 is driven by a drive signal input from the control unit, and noise included in the drive signal causes the actuator unit (this embodiment). In this case, the actuator portion is made up of a diaphragm and the piezoelectric element 300). When the resonance frequency coincides with the resonance frequency of the piezoelectric element 300, the actuator portion resonates and may be damaged. There is a need.

  Therefore, in the recording head of the present embodiment, a low pass filter is provided to remove this noise. Hereinafter, it demonstrates in detail using FIG. FIG. 3A is a block diagram for explaining a control method using the recording head of this embodiment, and FIG. 3B is a circuit diagram showing an example of the configuration of a low-pass filter.

  The ink jet recording apparatus I including the ink jet recording head 1 according to the present embodiment includes a control unit 200. The control unit 200 is for controlling the operation of the ink jet recording apparatus I. The control unit 200 controls the ink jet recording apparatus I itself (for example, operates a paper feed mechanism) and the ink jet type recording apparatus I. And a head controller 202 for controlling the recording head 1. Various signals for driving the ink jet recording head 1 are output from the head control unit 202 and input to the drive circuit 120 of the ink jet recording head 1. The drive circuit 120 is provided with a low-pass filter 203, and among the various signals described above, the drive signal S 1 for driving the piezoelectric element 300 generated by the head control unit 202 is the low-pass filter of the drive circuit 120. 203.

The low-pass filter 203 has a cutoff frequency set to the resonance frequency of the actuator unit described above. Here, when the actuator unit is configured by the diaphragm and the piezoelectric element 300 as in the present embodiment, the resonance frequency of the actuator unit is determined by the material of the diaphragm and the size of the vibration part of the diaphragm (that is, It varies depending on the size of the pressure generation chamber 12). In the present embodiment, as described above, the elastic film 50 is made of silicon dioxide, and the insulator film 55 is made of zirconium oxide (ZrO ₂ ). The thickness of the diaphragm is 1000 to 2000 μm, and the size of the vibration part of the diaphragm is the width of the pressure generating chamber 12 (direction in which the pressure generating chambers 12 are arranged): 45 to 60 μm × the pressure generating chamber 12 Length (direction perpendicular to the direction in which the pressure generation chambers 12 are arranged): 800 to 1000 μm. In this case, the resonance frequency of the actuator unit at the time of ink filling is 0.14 to 0.17 MHz. In the present embodiment, a low-pass filter configured to have a cutoff frequency of 0.14 MHz so as to be removed from the lowest resonance frequency component is used.

  As the low-pass filter 203, any low-pass filter may be used as long as the resonance frequency can be set. For example, in the present embodiment, the low-pass filter having the configuration including the capacitor element C and the resistor R shown in FIG. 3B is used, but a low-pass filter including a coil element and a capacitor element may be used.

  Switching elements 204 to 206 that are parallel to each other are connected to the low-pass filter 203. Each of the switching elements 204 to 206 is provided in series with each of the piezoelectric elements 300 as the capacitive addition elements PZT. In the drawing, as an example, three piezoelectric elements 300 and the switching elements 204 to 206 are connected. Show. The piezoelectric element 300 to which the signal is applied is determined by the on / off states of the switching elements 204 to 206. The on / off state of the switching element is determined by the various signals described above.

  With this configuration, the drive signal S1 output from the head control unit of the control unit 200 is input to the low-pass filter 203 of the drive circuit 120, and frequency components equal to or higher than the cutoff frequency of the low-pass filter 203 are removed. . That is, the low-pass filter 203 removes noise that is the resonance frequency of the actuator unit. Next, the drive signal S1 from which noise has been removed is input to the switching elements 204 to 206, and when the switching elements 204 to 206 are in the ON state, correspondingly input to each piezoelectric element 300.

  That is, the ink jet recording head 1 operates as follows. First, ink is taken in from an external ink supply means (not shown), and the interior from the reservoir 100 to the nozzle opening 21 is filled with ink. Thereafter, the drive signal S1 output from the control unit 200 is input to the low-pass filter 203 of the drive circuit 120, and a frequency component equal to or higher than the cutoff frequency of the low-pass filter 203 is removed. The removed drive signal S1 is applied to the piezoelectric element 300 via the switching elements 204 to 206 that are in the on state. As a result, a voltage is applied between each of the lower electrode 60 and the upper electrode 80 corresponding to the pressure generating chamber 12, and the elastic film 50, the insulator film 55, the lower electrode 60, and the piezoelectric layer 70 are bent and deformed. As a result, the pressure in each pressure generating chamber 12 increases and ink droplets are ejected from the nozzle openings 21.

  As described above, in the present embodiment, since the low-pass filter 203 is provided, noise that is the resonance frequency of the actuator unit is removed. Therefore, the resonance causes the actuator unit (in this embodiment, the diaphragm and the piezoelectric element). 300) is prevented from being damaged.

  In the manufacturing process of the ink jet recording head 1, a process called an aging process is usually performed. This aging process is for appropriately adjusting the variation of the displacement amount of each piezoelectric element 300. For example, a driving signal having a higher voltage and a higher frequency than in actual use is applied to the piezoelectric element in the same manner as in actual use. A predetermined number of pulses are applied to the piezoelectric element 300 to drive it. Also in this process, since the low-pass filter 203 is provided, the resonance frequency component of the actuator part included in the applied drive signal can be removed. Therefore, the actuator part (in this embodiment, in the aging process) Damage to the diaphragm and the piezoelectric element 300) can be prevented. If the resonance frequency in such a manufacturing process is before adhering the nozzle plate 20 to the flow path forming substrate 10 in which the pressure generation chamber 12 is formed, the resonance frequency of the actuator portion is 2.75 to 2.95 MHz. is there. Further, if the nozzle plate is adhered and before ink filling, the resonance frequency of the actuator portion is 2.7 to 2.8 MHz. Therefore, in this embodiment, since the cutoff frequency is set to 0.14 MHz, which is the lowest resonance frequency, these resonance frequency components can also be removed.

  Such an ink jet recording head 1 constitutes a part of a recording head unit including an ink flow path communicating with an ink cartridge or the like, and is mounted on the ink jet recording apparatus I. FIG. 4 is a schematic view showing an example of the ink jet recording apparatus. As shown in FIG. 4, a recording head unit 1A having an ink jet recording head 1 (not shown in FIG. 4) is provided with detachable cartridges 2A and 2B constituting ink supply means, and this recording head unit 1A is mounted. The carriage 3 is provided on a carriage shaft 5 attached to the apparatus main body 4 so as to be movable in the axial direction. The recording head units 1A and 1B, for example, are configured to eject a black ink composition and a color ink composition, respectively. The ink jet recording apparatus I is provided with the above-described control unit 200 (not shown).

  Then, the driving force of the driving motor 6 is transmitted to the carriage 3 via a plurality of gears and a timing belt 7 (not shown), so that the carriage 3 on which the recording head unit 1A is mounted is moved along the carriage shaft 5. On the other hand, the apparatus body 4 is provided with a platen 8 along the carriage shaft 5, and a recording sheet S, which is a recording medium such as paper fed by a paper feed roller (not shown), is conveyed on the platen 8. It is like that.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment. In this embodiment, the low-pass filter 203 is provided in the drive circuit 120 of the recording head. However, the low-pass filter 203 is connected to the switching elements 204 to 206 from the output of signal generation means (not shown) that generates a drive signal. If it is provided in between, it may be provided in the ink jet recording apparatus I. For example, a low-pass filter 203 may be provided in the control unit 200 as shown in FIG. 5A, and the configuration of the drive circuit 120 is incorporated in the control unit 200 itself as shown in FIG. A low pass filter 203 may be provided upstream of the elements 204 to 206. In any case, by providing the low-pass filter 203 on the upstream side of the switching elements 204 to 206, the resonance frequency component of the drive signal S1 input to the plurality of piezoelectric elements 300 can be removed by one low-pass filter. it can.

  Moreover, in this embodiment, although the silicon single crystal substrate was illustrated as the flow-path formation board | substrate 10, it does not specifically limit to this. For example, the present invention is effective for an SOI substrate, a glass substrate, an MgO substrate, and the like.

  In the above-described embodiment, the pressure generating means for causing the pressure change in the pressure generating chamber 12 has been described using the actuator unit having the thin film type piezoelectric element 300. However, the present invention is not particularly limited thereto, and for example, a green sheet is used. A thick film type actuator device formed by a method such as affixing or a longitudinal vibration type actuator device in which piezoelectric materials and electrode forming materials are alternately stacked and expanded and contracted in the axial direction can be used.

  Further, in each of the above-described embodiments, the actuator unit is composed of the diaphragm and the piezoelectric element 300. However, when the lower electrode 60 constituting the piezoelectric element also functions as the diaphragm, the low-pass filter is blocked. The frequency is set to another resonance frequency. That is, in this case, the resonance frequency of the actuator part depends on the material of the lower electrode, the size of the vibrating part, etc. in addition to the material of the diaphragm, the size of the vibrating part of the diaphragm, etc. It is set in consideration of Of course, when the actuator part does not have a diaphragm and the lower electrode 60 functions as a diaphragm, the resonance frequency of the actuator part depends on the material of the lower electrode and the size of the vibrating part. is there.

  In the above-described embodiment, the ink jet recording head has been described as an example of the liquid ejecting head. However, the present invention is widely applied to all liquid ejecting heads, and the liquid ejecting ejects a liquid other than ink. Of course, the present invention can also be applied to a head manufacturing method. Other liquid ejecting heads include, for example, various recording heads used in image recording apparatuses such as printers, color material ejecting heads used in the manufacture of color filters such as liquid crystal displays, organic EL displays, and FEDs (field emission displays). Examples thereof include an electrode material ejection head used for electrode formation, a bioorganic matter ejection head used for biochip production, and the like.

FIG. 3 is an exploded perspective view of the recording head according to the embodiment of the invention. 2A and 2B are a plan view and a cross-sectional view of a recording head according to an embodiment of the invention. 1 is a block diagram of a recording apparatus according to an embodiment of the present invention. It is the schematic which shows an example of the recording device which concerns on embodiment of this invention. 1 is a block diagram of a recording apparatus according to an embodiment of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Flow path formation board | substrate, 12 Pressure generation chamber, 13 Communication part, 14 Ink supply path, 15 Communication path, 17 Groove part, 18 Electronic element formation film, 20 Nozzle plate, 21 Nozzle opening, 30 Protection board, 31 Reservoir part, 32 Piezoelectric element holding unit, 40 compliance substrate, 50 elastic film, 55 insulator film, 60 lower electrode, 70 piezoelectric layer, 80 upper electrode, 90 lead electrode, 100 reservoir, 120 drive circuit, 200 control unit, 203 low-pass filter, 204-206 switching element, 300 piezoelectric element

Claims (6)

A flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting liquid is formed, an actuator section having at least a pressure generating element in a region facing the pressure generating chamber of the flow path forming substrate, A signal processing unit that processes the drive signal output from the control unit that generates and outputs a drive signal for driving the actuator unit, and sends the drive signal to the actuator unit;
The liquid ejecting head according to claim 1, wherein a low-pass filter that removes a resonance frequency component of the actuator unit included in the drive signal is provided in the signal processing unit.   The signal processing unit is provided with a switching element connected in series to the actuator unit for each actuator unit, and between the switching element and the input unit of the input signal of the signal processing unit. The liquid jet head according to claim 1, wherein the low-pass filter is provided.   The liquid jet head according to claim 1, wherein a cutoff frequency of the low-pass filter is 0.14 MHz or less.   The actuator section is a piezoelectric element including a diaphragm and a lower electrode, a piezoelectric layer, and an upper electrode provided in a region opposite to the pressure generating chamber of the diaphragm. 4. The liquid jet head according to any one of 3 above. A control unit that generates and outputs a drive signal for driving the actuator unit by the drive signal generation unit; a flow path forming substrate in which a pressure generation chamber communicating with a nozzle opening that ejects the liquid is formed; Liquid jetting comprising: the actuator unit having at least a pressure generating element in a region facing the pressure generating chamber of the path forming substrate; and a signal processing unit for processing a drive signal from the control unit and sending it to the actuator unit With a head,
A liquid ejecting apparatus, comprising: a low-pass filter that removes a resonance frequency component of the actuator unit included in the drive signal between the drive signal generation unit and the signal processing unit. A flow path forming substrate in which a pressure generating chamber communicating with a nozzle opening for ejecting liquid is formed, an actuator section having at least a pressure generating element in a region facing the pressure generating chamber of the flow path forming substrate, and control In a liquid ejecting head control method comprising: a signal processing unit that processes a drive signal output from the unit for driving the actuator unit and sends the drive signal to the actuator unit;
A method of controlling a liquid jet head, comprising: removing a resonance frequency component of the actuator unit included in the drive signal by a low-pass filter provided in the signal processing unit.

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