CN109130500B

CN109130500B - Liquid ejection head, liquid ejection apparatus, and drive control circuit and drive method thereof

Info

Publication number: CN109130500B
Application number: CN201810613050.5A
Authority: CN
Inventors: 松本大辅; 松冈宏纪
Original assignee: Seiko Epson Corp
Current assignee: Seiko Epson Corp
Priority date: 2017-06-16
Filing date: 2018-06-14
Publication date: 2021-02-09
Anticipated expiration: 2038-06-14
Also published as: JP2019001079A; CN109130500A; JP6969170B2

Abstract

The invention provides a liquid ejection head, a liquid ejection apparatus, a drive control circuit and a drive method thereof. In a drive control circuit for a liquid discharge apparatus including a liquid discharge head for discharging a liquid by varying a pressure of an internal space filled with the liquid by a drive element, the liquid discharge head includes a head drive circuit having a first terminal to which a drive waveform signal having a drive waveform for driving the drive element is input and a second terminal for outputting a state signal indicating a state of the liquid discharge head, the drive waveform signal includes a first drive waveform signal and a second drive waveform signal having different drive waveforms, the drive control circuit inputs the first drive waveform signal to the first terminal when the state signal from the second terminal is a predetermined signal, on the other hand, when the state signal from the second terminal is not a predetermined signal, the second drive waveform signal is input to the first terminal.

Description

Liquid ejection head, liquid ejection apparatus, and drive control circuit and drive method thereof

Technical Field

The present invention relates to a technique for ejecting a liquid such as ink.

Background

In a liquid ejection head that ejects a liquid such as ink from nozzles by varying the pressure of a pressure chamber filled with the liquid such as ink by a driving element, the ejection rate of the liquid changes according to the natural vibration cycle of the liquid in the pressure chamber, and therefore, the driving waveform of the driving element may be set in consideration of this situation. However, for example, patent document 1 discloses that when UV ink including a photo-curable resin is ejected, since a diaphragm (a sealing plate) constituting a wall surface of a pressure chamber is gradually deteriorated by the UV ink and plasticity is changed, a natural vibration period of the ink in the pressure chamber varies with time, and the ink cannot be stably ejected with a drive waveform (a drive pulse) of a drive element that is initially set. Therefore, patent document 1 adopts a method in which the driving waveform is corrected in accordance with the elapsed time from the filling of the pressure chamber with the ink, whereby the ink can be stably ejected even if the natural vibration cycle of the ink in the pressure chamber fluctuates with time.

Further, when a driving waveform, which is the resonance frequency of the vibrating plate, is continuously applied to the piezoelectric element, cracks (cracks) may be generated in the vibrating plate or the piezoelectric element, and the vibrating plate or the piezoelectric element may be damaged. Therefore, a drive waveform that does not become the resonance frequency of the diaphragm is set at the time of manufacturing. However, air bubbles may be mixed into the pressure chamber, the liquid storage chamber, and the like during printing, and when the air bubbles are mixed, the resonance frequency of the vibration plate suddenly fluctuates. Therefore, the frequency of the drive waveform may coincide with the varied resonance frequency, and the vibration plate or the piezoelectric element may be broken by cracks. If the diaphragm and the piezoelectric element are damaged, printing cannot be continued thereafter, and a trouble time may occur. However, in patent document 1, since abrupt variation in the vibration frequency due to mixing of air bubbles or the like is not considered, there is a possibility that such a problem cannot be completely eliminated.

Patent document 1: japanese patent laid-open publication No. 2010-167724

Disclosure of Invention

In view of the above, an object of the present invention is to stably continue to discharge liquid regardless of the state of a liquid discharge head such as the presence or absence of bubbles, and to suppress the occurrence of a failure time.

In a first mode

In order to solve the above-described problems, a drive control circuit of a liquid discharge apparatus according to a preferred aspect (aspect one) of the present invention is a drive control circuit of a liquid discharge apparatus including a liquid discharge head that discharges a liquid by varying a pressure of an internal space filled with the liquid by a drive element, the liquid discharge head including a head drive circuit having a first terminal to which a drive waveform signal having a drive waveform for driving the drive element is input and a second terminal that outputs a state signal indicating a state of the liquid discharge head, the drive waveform signal including a first drive waveform signal and a second drive waveform signal having different drive waveforms, the drive control circuit inputs a first drive waveform signal to the first terminal when the state signal from the second terminal is a predetermined signal, and inputs a second drive waveform signal to the first terminal when the state signal from the second terminal is not the predetermined signal.

According to the above aspect, by applying the drive waveform to the drive element and vibrating the vibration plate or the like, the pressure in the internal space of the liquid ejection head can be varied and the liquid can be ejected. In this case, the vibration plate can be vibrated by applying different drive waveforms to the drive element according to the state of the liquid ejection head indicated by the state signal. Therefore, stable liquid discharge can be continuously performed, and occurrence of a failure time can be suppressed.

In this case, the state of the liquid ejection head also changes depending on whether or not air bubbles or the like are present in the internal space of the liquid ejection head (the pressure chamber, the liquid storage chamber, or the like), and therefore the state signal can be changed. For example, the state signal in the case where the bubble is present may be a predetermined signal, and the state signal in the case where the bubble is not present may not be a predetermined signal. Thus, the presence or absence of the bubble can be determined based on whether or not the state signal is a predetermined signal. In this case, in the case where the state signal is a predetermined signal (for example, in the case where a bubble is present), the first drive waveform signal is input to the first terminal, and in the case where the state signal is not a predetermined signal (for example, in the case where a bubble is not present), the second drive waveform signal having a drive waveform different from that of the first drive waveform signal is input to the first terminal. In this way, the vibration plate can be vibrated by applying different drive waveforms to the drive element depending on the state of the liquid ejection head (presence or absence of bubbles). Therefore, even if the resonance frequency of the diaphragm fluctuates depending on the presence or absence of the bubble, the generation of the crack in the diaphragm and the driving element can be suppressed, and therefore, the stable liquid discharge can be continued regardless of the presence or absence of the bubble, and the occurrence of the failure time can be suppressed.

Mode two

In order to solve the above-described problems, a drive control circuit of a liquid discharge apparatus according to a preferred aspect (aspect two) of the present invention is a drive control circuit of a liquid discharge apparatus including a liquid discharge head that discharges a liquid by varying a pressure of an internal space filled with the liquid by a drive element, the liquid discharge head including a head drive circuit having a first terminal to which a drive signal having a plurality of drive waveforms for driving the drive element is input and a second terminal that outputs a state signal indicating a state of the liquid discharge head, the head drive circuit outputting a drive signal having a drive waveform selected from among the drive waveform signals to the drive element, the drive control circuit inputs the first drive signal to the drive element when the state signal from the second terminal is a predetermined signal, and inputs the second drive signal to the drive element when the state signal from the second terminal is not the predetermined signal.

According to the above aspect, by applying the drive waveform to the drive element and vibrating the vibration plate or the like, the pressure in the internal space of the liquid ejection head can be varied and the liquid can be ejected. In this case, it is possible to apply different drive waveforms to the drive element and to vibrate the vibration plate according to the state of the liquid ejection head indicated by the state signal. Therefore, the liquid can be continuously and stably discharged, and the occurrence of a failure time can be suppressed.

In this case, for example, the state signal in the case where the bubble is present may be a predetermined signal, and the state signal in the case where the bubble is not present may not be a predetermined signal. Thus, in the case where the state signal is a predetermined signal (for example, in the case where a bubble is present), the first drive signal is output to the drive element, and in the case where the state signal is not a predetermined signal (for example, in the case where a bubble is not present), the second drive signal having a drive waveform different from that of the first drive signal is output to the drive element. In this way, the vibration plate can be vibrated by applying different drive waveforms to the drive element depending on the state of the liquid ejection head (presence or absence of bubbles). Therefore, even if the resonance frequency of the diaphragm fluctuates depending on the presence or absence of the bubble, the generation of the crack in the diaphragm and the driving element can be suppressed, and therefore, the stable liquid discharge can be continued regardless of the presence or absence of the bubble, and the occurrence of the failure time can be suppressed.

Mode III

In order to solve the above-described problem, a drive control circuit of a liquid discharge apparatus according to a preferred aspect (aspect three) of the present invention is a drive control circuit of a liquid discharge apparatus including a liquid discharge head that discharges a liquid by varying a pressure of an internal space filled with the liquid by a drive element, the liquid discharge head including a head drive circuit having a first terminal to which a drive waveform signal having a plurality of drive waveforms for driving the drive element is input, a second terminal to which a state signal indicating a state of the liquid discharge head is output, and a third terminal to which a selection signal for selecting a drive waveform to be applied to the drive element from among the drive waveform signals is input, the selection signal includes a first selection signal and a second selection signal for selecting different drive waveforms, and the drive control circuit inputs the first selection signal to the third terminal when the state signal from the second terminal is a predetermined signal, and inputs the second selection signal to the third terminal when the state signal from the second terminal is not the predetermined signal.

According to the above aspect, by applying the drive waveform to the drive element to vibrate the vibration plate or the like, the pressure in the internal space of the liquid ejection head can be varied to eject the liquid. In this case, it is possible to apply different drive waveforms to the drive element and to vibrate the vibration plate according to the state of the liquid ejection head indicated by the state signal. Therefore, stable liquid discharge can be continuously performed, and occurrence of a failure time can be suppressed.

In this case, for example, the state signal in the case where the bubble is present may be a predetermined signal, and the state signal in the case where the bubble is not present may not be a predetermined signal. Thus, in the case where the state signal is a predetermined signal (for example, in the case where a bubble is present), the first selection signal is output to the third terminal, and in the case where the state signal is not a predetermined signal (for example, in the case where a bubble is not present), the second drive signal that selects a drive waveform different from the drive waveform selected by the first selection signal is output to the third terminal. In this way, the vibration plate can be vibrated by applying different drive waveforms to the drive element depending on the state of the liquid ejection head (presence or absence of bubbles). Therefore, even if the resonance frequency of the diaphragm fluctuates depending on the presence or absence of the bubble, the generation of the crack in the diaphragm and the driving element can be suppressed, and therefore, the stable liquid discharge can be continued regardless of the presence or absence of the bubble, and the occurrence of the failure time can be suppressed.

Mode IV

In a preferred example (mode four) of the first to third modes, the different drive waveforms are waveforms of the voltage signal, and at least one of a slope of the waveform, a maximum value of the potential, a minimum value of the potential, an amplitude of the waveform, and a frequency of the waveform is different. According to the above aspect, by switching the drive waveforms different in at least one of the slope of the waveform, the maximum value of the potential, the minimum value of the potential, the amplitude of the waveform, and the frequency of the waveform, it is possible to perform ejection of the liquid with different drive waveforms according to the presence or absence of bubbles or the amount of bubbles. Further, by making the slope of the waveform or the like different, the ejection amount of the liquid ejected when liquid is present and the size of the liquid droplet can also be changed. Further, if the amplitude of the drive waveform is increased when the amount of bubbles is large, it is possible to discharge liquid droplets even if pressure fluctuations are absorbed by the bubbles. Further, by preventing the amplitude of the drive waveform from becoming too small, it is possible to prevent the occurrence of fogging due to absorption of pressure fluctuations.

Mode five

In a preferred example (mode five) of the first to fourth modes, the liquid ejection head includes: a drive element; a pressure chamber; and a diaphragm which is disposed on a wall surface constituting an internal space between the pressure chamber and the driving element and vibrates by the driving element, wherein the different driving waveforms are waveforms in which presence or absence of resonance of the diaphragm is switched. According to the above aspect, since the different drive waveforms are waveforms in which the presence or absence of resonance of the diaphragm is switched, even when the diaphragm resonates with one drive waveform, the diaphragm can be prevented from resonating with the other drive waveform. Further, according to this aspect, since the resonance of the diaphragm can be suppressed, the occurrence of cracks can be suppressed even if the diaphragm is formed as a thin film. Therefore, by forming the diaphragm as a thin film, high-quality printing can be performed at high speed, and the liquid ejection head can be easily miniaturized.

Mode six

In a preferred example (mode six) of any one of the first to fifth modes, the liquid ejecting apparatus includes a display unit that displays an operation mode of the liquid ejecting apparatus and changes the operation mode displayed by the display unit in accordance with the state signal. According to the above aspect, since the operation mode displayed on the display unit is changed in accordance with the state signal, the operation mode executable by the user can be restricted in accordance with the state signal. The operation mode of this embodiment includes, for example, a high-quality mode, a high-speed mode, a mode with complementary printing, a mode without complementary printing, and the like. For example, one mode is displayed when the state signal is a predetermined signal (when a bubble is present), and the other mode is displayed when the state signal is not a predetermined signal (when a bubble is not present). Since the driving waveform used differs depending on the operation mode, the vibration plate can be prevented from resonating even if the resonance frequency of the vibration plate fluctuates.

Mode seven

In a preferred example (mode seven) of any one of the first to sixth modes, different drive waveforms are applied to the drive element in accordance with the amount of air bubbles in the internal space of the liquid ejection head. According to the above aspect, since different drive waveforms are applied to the drive element according to the amount of bubbles in the internal space of the liquid ejection head, stable liquid ejection can be continuously performed regardless of the amount of bubbles.

Mode eight

In a preferred example (mode eight) of any one of the first to seventh modes, different drive waveforms are applied to the drive elements in accordance with the continuous application time of the drive waveforms to the drive elements. According to the above aspect, since different drive waveforms are applied to the drive element according to the continuous application time of the drive waveform to the drive element, even if the resonance frequency of the vibration plate fluctuates due to the bubble becoming larger as the temperature of the liquid ejection head rises due to the continuous application time of the drive waveform, the occurrence of cracks due to the resonance of the vibration plate can be suppressed.

The ninth mode

In a preferred example of the eighth aspect (the ninth aspect), different drive waveforms are applied to the drive element in accordance with positions of air bubbles included in the internal space of the liquid ejection head. According to the above aspect, since different drive waveforms are applied to the drive element according to the position of the bubble included in the internal space of the liquid ejection head, even if the resonance frequency of the vibration plate changes depending on the position of the bubble, the occurrence of a crack due to the resonance of the vibration plate can be suppressed.

A cross mode

In a preferred example (mode ten) of any one of the first to ninth modes, the maximum width of the liquid ejecting apparatus capable of serial printing is 24 inches or more and 75 inches or less. According to the above aspect, even when the maximum width that can be printed in series is 24 inches or more and 75 inches or less, the occurrence of cracks due to resonance of the vibration plate can be suppressed. Further, since the maximum width that can be serially printed is 24 inches or more and 75 inches or less, the total length of the signal line that transmits the drive signal or the like can be about 1m to 3m, and therefore, the impedance and the inductance of the signal line can be reduced as compared with the case where the maximum width that can be serially printed is 75 inches or more. Therefore, it is possible to suppress a malfunction or malfunction due to an overshoot (over shot) or an undershoot (under shot) of the drive signal or the like.

Mode eleven

In a preferred example of the tenth mode (mode eleventh), the width of the liquid ejecting apparatus that can be printed in series corresponds to a medium having any one of the sizes of 24 inches, 36 inches, 44 inches, and 64 inches. According to the above aspect, since the medium corresponds to any one of the sizes of 24 inches, 36 inches, 44 inches, and 64 inches, even when printing is performed on the medium, it is possible to suppress the occurrence of cracks due to resonance of the vibration plate.

The twelve mode

In a preferred example (mode twelve) of any one of the first to the eleventh modes, the liquid discharge head discharges the liquid with a drive waveform having a frequency of 30kHz or higher. According to the above aspect, since the liquid is discharged with the high-frequency drive waveform of 30kHz or more, printing can be performed at high speed, and thus the vibration plate can be prevented from resonating even when the resonance frequency of the vibration plate is 30kHz or more. Therefore, even in the case of high-speed printing in which the frequency of the drive waveform is 30kHz or more, stable liquid discharge can be continuously performed regardless of the presence or absence of bubbles, and the occurrence of a trouble time can be suppressed.

Mode thirteen

In order to solve the above problem, a liquid ejecting apparatus according to a preferred embodiment (mode thirteen) of the present invention includes: a liquid ejection head that ejects liquid by varying a pressure of an internal space filled with the liquid by a driving element; and a drive control circuit that applies a drive waveform to the drive element, the drive control circuit switching the drive waveform applied to the drive element in accordance with an amount of air bubbles in an internal space of the liquid ejection head. According to the above aspect, since the drive control circuit switches the drive waveform applied to the drive element in accordance with the amount of air bubbles in the internal space of the liquid ejection head, it is possible to apply a different drive waveform to the drive element in accordance with the amount of air bubbles and to vibrate the vibration plate. Therefore, stable liquid discharge can be continuously performed regardless of the amount of bubbles in the internal space of the liquid discharge head, and occurrence of a failure time can be suppressed.

Fourteen modes

In order to solve the above problem, a liquid ejection head according to a preferred aspect (mode fourteen) of the present invention ejects liquid by varying a pressure of an internal space filled with the liquid by a driving element, and in the liquid ejection head, a driving waveform applied to the driving element is switched according to an amount of air bubbles in the internal space of the liquid ejection head. According to the above aspect, since the drive waveform applied to the drive element is switched according to the amount of bubbles in the internal space of the liquid ejection head, it is possible to apply a different drive waveform to the drive element according to the amount of bubbles in the internal space of the liquid ejection head to vibrate the vibration plate. Therefore, stable liquid discharge can be continuously performed regardless of the amount of bubbles in the internal space of the liquid discharge head, and occurrence of a failure time can be suppressed.

Mode fifteen

In order to solve the above problem, a method according to a preferred aspect (aspect fifteen) of the present invention is a method of driving a liquid discharge apparatus including: a liquid ejection head that ejects liquid by varying a pressure of an internal space filled with the liquid by a driving element; and a drive control circuit that applies a drive waveform to the drive element, the drive control circuit switching the drive waveform applied to the drive element in accordance with an amount of air bubbles in an internal space of the liquid ejection head. According to the above aspect, since the drive control circuit switches the drive waveform applied to the drive element in accordance with the amount of air bubbles in the internal space of the liquid ejection head, it is possible to apply a different drive waveform to the drive element in accordance with the amount of air bubbles to vibrate the vibration plate. Therefore, stable liquid discharge can be continuously performed regardless of the amount of bubbles in the internal space of the liquid discharge head, and occurrence of a failure time can be suppressed.

In a sixteen way

In order to solve the above problem, a method according to a preferred aspect (mode sixteenth) of the present invention is a method of driving a liquid discharge apparatus including: a liquid ejection head that ejects liquid by varying a pressure of an internal space filled with the liquid by a driving element; a drive control circuit that switches an operation mode applied to a drive element between a first mode and a second mode, which are operation modes in which different drive waveforms are applied to the drive element, according to an amount of air bubbles in an internal space of the liquid ejection head; a storage device that stores a drive waveform, the drive method comprising: a first step of storing the drive waveform of the first pattern in a storage device; and a second step of storing the drive waveform of the second pattern in the storage device. According to the above aspect, since the drive waveform of the first pattern and the drive waveform of the second pattern can be freely stored in the storage device, the operability is good. Further, since the liquid can be ejected in the pattern of the drive waveform stored in the storage device, it is possible to realize printing in accordance with the preference of the user while suppressing the occurrence of a trouble time.

Drawings

Fig. 1 is a configuration diagram of a liquid discharge apparatus according to a first embodiment of the present invention.

Fig. 2 is a functional configuration diagram for explaining a drive control circuit of the liquid discharge apparatus.

Fig. 3 is a sectional view of the liquid ejecting section.

Fig. 4 is a diagram for explaining an operation mode of the first embodiment.

Fig. 5 is a flowchart showing control performed when the liquid ejecting apparatus performs printing.

Fig. 6 is a diagram for explaining an operation mode of the second embodiment.

Fig. 7 is a diagram for explaining an operation mode of the third embodiment.

Fig. 8 is a diagram for explaining a drive waveform signal in the operation mode of the fourth embodiment.

Fig. 9 is a diagram for explaining a drive waveform selected in the operation mode of the fourth embodiment.

Fig. 10 is a diagram for explaining a drive waveform signal in the operation mode of the fifth embodiment.

Fig. 11 is a diagram for explaining a drive waveform selected in the operation mode of the fifth embodiment.

Detailed Description

First embodiment

Fig. 1 is a partial configuration diagram of a liquid discharge apparatus 10 according to a first embodiment of the present invention. The liquid discharge apparatus 10 of the present embodiment is an ink jet printing apparatus that discharges ink as an example of a liquid onto a medium 12 such as printing paper. The liquid ejection device 10 shown in fig. 1 includes a control unit 20, a transport mechanism 22, a carriage 24, and a liquid ejection head 26. Although fig. 1 illustrates a case where one liquid ejection head 26 is mounted on the carriage 24, the present invention is not limited to this, and a plurality of liquid ejection heads 26 may be mounted on the carriage 24. A liquid container (ink cartridge) 14 for storing ink is attached to the liquid ejecting apparatus 10.

The liquid container 14 is an ink tank type ink cartridge including a box-shaped container that is attachable to and detachable from the main body of the liquid ejecting apparatus 10. The liquid container 14 is not limited to a box-shaped container, and may be an ink bag type ink cartridge including a bag-shaped container. The liquid container 14 stores ink. The ink may be black ink or color ink. The ink stored in the liquid container 14 is supplied (pumped) to the liquid ejection head 26 by a pump (not shown).

The control Unit 20 includes a control device 202 such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage device 203 such as a semiconductor memory, and is configured to comprehensively control each element of the liquid ejecting apparatus 10 by the control device 202 executing a control program stored in the storage device 203. As shown in fig. 1, print data G indicating an image to be formed on the medium 12 is input to the control unit 20 from an external device (not shown) such as a host computer. The control unit 20 controls each element of the liquid discharge apparatus 10 so that an image designated by the print data G is formed on the medium 12.

The conveyance mechanism 22 conveys the medium 12 in the Y direction based on the control of the control unit 20. The liquid discharge head 26 is mounted on the carriage 24 having a substantially box shape, and discharges ink supplied from the liquid tank 14 to the medium 12 under the control of the control unit 20. The control unit 20 reciprocates the carriage 24 in the X direction intersecting the Y direction. The liquid ejection head 26 ejects ink onto the medium 12 in parallel with the conveyance of the medium 12 by the conveyance mechanism 22 and the repetitive reciprocating movement of the carriage 24, thereby forming a desired image on the surface of the medium 12. Further, the liquid container 14 can be mounted on the carriage 24 together with the liquid ejection head 26.

A nozzle row is arranged on the discharge surface (the surface facing the medium 12) 260 of the liquid discharge head 26. The nozzle row is a set of a plurality of nozzles N arranged linearly along the Y direction. The ink supplied from the liquid container 14 is ejected from the nozzle N. The number and arrangement of the nozzle rows are not limited to those illustrated, and two or more nozzle rows may be arranged on the discharge surface 260 of the liquid discharge head 26, or a plurality of nozzle rows may be arranged in, for example, a cross arrangement or a staggered arrangement. The direction perpendicular to the X-Y plane (the plane parallel to the surface of the medium 12) is labeled as the Z direction.

Fig. 2 is a functional configuration diagram for explaining the drive control circuit 21 of the liquid discharge apparatus 10. In fig. 2, the conveying mechanism 22, the carriage 24, and the like are not shown for convenience of explanation. The liquid discharge apparatus 10 includes a drive control circuit 21. The drive control circuit 21 is electrically connected to the head drive circuit 262 through terminals P1 to P6 described later. The drive control circuit 21 is provided in the control unit 20, and the head drive circuit 262 is provided in the liquid ejection head 26. However, the head drive circuit 262 may be provided in a component other than the liquid ejection head 26. When the control device 202 executes the control program, the control device 202 functions as the drive signal generation unit 40, the control unit 50, and the determination unit 52. The drive signal generation unit 40, the control unit 50, and the determination unit 52 may be configured by circuits. The control unit 50 may be the processor 50. The control unit 50 controls the drive signal generation unit 40. The storage device 203 stores a data table C. The data table C may be stored in a memory provided in the storage device 203. The drive signal generating unit 40 generates a drive waveform signal COM. The drive waveform signal COM is, for example, the drive waveforms W1 and W2 shown in fig. 4, that is, a waveform of a voltage signal including a plurality of potentials (VL, VH, and the like) having a potential difference with respect to the reference potential (intermediate potential) VM. The drive waveform of the drive waveform signal COM is generated at a predetermined cycle T. The period T of the drive waveform signal COM corresponds to one pixel.

The piezoelectric element 74 of the present embodiment is driven by a plurality of operation modes, and a drive waveform of the drive waveform signal COM different for each operation mode is applied to the piezoelectric element 74. In fig. 4, as the operation mode, the drive waveform W1 of the first drive waveform signal COM1 of the first mode and the drive waveform W2 of the second drive waveform signal COM2 of the second mode are illustrated. Data (for example, voltage data) for generating the driving waveform signal COM is stored in the data table C. When generating the drive waveform signal COM, the control unit 50 reads data corresponding to the drive waveform included in the drive waveform signal COM from the data table C, and generates the drive waveform signal COM by the drive signal generating unit 40. The details of the operation mode and the drive waveforms W1 and W2 will be described later.

The operation modes are not limited to the first mode and the second mode, and the user can freely select and execute each operation mode. For example, as shown in fig. 2, the liquid ejecting apparatus 10 includes an operation panel 60 formed of a touch panel, and the operation panel 60 includes a display unit 62. The operation panel 60 is an operation panel that can be operated by a user, and a plurality of buttons (not shown) are displayed on the display unit 62. A selection button of the operation mode is also displayed on the display unit 62, and the user touches the operation mode button displayed on the display unit 62 to execute the operation mode.

As shown in fig. 2, the liquid ejection head 26 includes a head driving circuit 262 and a liquid ejection portion 264. The head driving circuit 262 drives the liquid ejecting section 264 based on the control of the control unit 20. The liquid ejecting section 264 ejects the ink supplied from the liquid container 14 from the plurality of nozzles N to the medium 12. The liquid discharge portion 264 includes a plurality of discharge portions 266 corresponding to the plurality of nozzles N. Each of the ejecting sections 266 ejects ink in response to the driving signal V output from the head driving circuit 262.

The drive waveform signal COM generated by the drive signal generation unit 40 and a selection signal (print signal) SI for designating whether ink is ejected or not for each nozzle N based on the drive waveform signal COM and print data are input from the drive control circuit 21 to the head drive circuit 262. The selection signal SI includes data for defining selection and non-selection of the drive waveform W included in the drive waveform signal COM. The drive waveform signal COM is input from the fourth terminal P4, which is an output terminal of the drive control circuit 21, to the first terminal P1, which is an input terminal of the head drive circuit 262. As for the input, as long as the fourth terminal P4 and the first terminal P1 are electrically connected, another circuit element may be present between the two terminals. The selection signal SI is input from the sixth terminal P6, which is an output terminal of the drive control circuit 21, to the third terminal P3, which is an input terminal of the head drive circuit 262. As for the input, as long as the sixth terminal P6 and the third terminal P3 are electrically connected, another circuit element may be present between the two terminals. The head drive circuit 262 generates a drive signal V corresponding to the drive waveform signal COM and the selection signal SI for each ejection unit 266, and outputs the drive signals V to the piezoelectric elements 74 of the plurality of ejection units 266 in parallel. Specifically, the head drive circuit 262 outputs the drive waveform W of the drive waveform signal COM as the drive signal V to the ejection unit 266, of the plurality of ejection units 266, which instructs ejection of ink by the selection signal SI, and outputs the reference potential VM as the drive signal to the ejection unit 266, which instructs non-ejection of ink by the selection signal SI.

Fig. 3 is a cross-sectional view of the liquid discharge section 264 focusing on any one of the discharge sections 266. The liquid ejecting section 264 shown in fig. 3 is a structure in which the pressure chamber substrate 72, the vibrating plate 73, the piezoelectric element 74, and the support 75 are disposed on one side of the flow channel substrate 71, and the nozzle plate 76 is disposed on the other side. The flow path substrate 71, the pressure chamber substrate 72, and the nozzle plate 76 are formed of, for example, a flat plate of silicon, and the support body 75 is formed by, for example, injection molding of a resin material. A plurality of nozzles N are formed on the nozzle plate 76. In the structure of fig. 3, the surface of the nozzle plate 76 facing the medium 12 constitutes the ejection surface 260 of the liquid ejection head.

The flow path substrate 71 is provided with an opening 712, branch flow paths 714, and a communication flow path 716. The branch flow path 714 and the communication flow path 716 are through holes formed for each nozzle N, and the opening 712 is an opening continuous across the plurality of nozzles N. A space in which the housing portion (concave portion) 752 formed in the support body 75 and the opening portion 712 of the flow path substrate 71 communicate with each other functions as a liquid storage chamber (reservoir) SR that stores the ink supplied from the liquid container 14 via the introduction flow path 754 of the support body 75.

An opening 722 is formed in the pressure chamber substrate 72 for each nozzle N. The vibration plate 73 is an elastically deformable flat plate member provided on the surface of the pressure chamber substrate 72 on the side opposite to the flow path substrate 71. The space sandwiched between the vibrating plate 73 and the flow path substrate 71 inside each opening 722 of the pressure chamber substrate 72 functions as a pressure chamber (cavity) SC filled with ink supplied from the liquid storage chamber SR through the branch flow path 714. Each pressure chamber SC communicates with the nozzle N via the communication flow passage 716 of the flow passage substrate 71. A space formed by the pressure chamber SC, the liquid storage chamber SR, the branch flow passage 714 that communicates the pressure chamber SC and the liquid storage chamber SR, the communication flow passage 716, and the nozzle N constitutes an internal space of the fluid ejection head 26.

The vibration plate 73 is disposed between the pressure chamber SC and the pressure element 74, and constitutes a wall surface (upper surface) of the pressure chamber SC (internal space of the liquid ejection head 26). Specifically, on the surface of the diaphragm 73 on the side opposite to the pressure chamber substrate 72, a piezoelectric element 74 is formed for each nozzle N. Each piezoelectric element 74 is a driving element having a piezoelectric body 774 interposed between the first motor 742 and the second motor 746. A drive waveform of the drive signal V is applied to one of the first electrode 742 and the second electrode 746, and a predetermined reference potential VM is applied to the other. When the piezoelectric element 74 is deformed by the drive waveform of the drive signal V and the vibration plate 73 vibrates, the pressure in the pressure chamber SC is varied, and the ink in the pressure chamber SC is ejected from the nozzle N. Specifically, the ink of the ejection amount according to the amplitude of the drive waveform of the drive signal V is ejected from the nozzle N. One discharge unit 266 illustrated in fig. 3 is a portion including the piezoelectric element 74, the vibration plate 73, the pressure chamber SC, and the nozzle N.

Further, of the first electrode 742 and the second electrode 746, an electrode to which the reference potential VM is applied may be a common electrode extending across the plurality of piezoelectric elements 74. In this manner, in the configuration of fig. 3, the piezoelectric element 74 is deformed by the drive waveform of the drive signal V, and the pressure of the pressure chamber SC is varied, so that the pressure in the internal space of the liquid discharge head 26 is varied, and the ink can be discharged from the nozzles N.

When a driving waveform, which is the resonance frequency of the diaphragm 73, is continuously applied to the piezoelectric element 74, cracks (cracks) may be generated in the diaphragm 73 and the piezoelectric element 74, and the diaphragm 73 and the piezoelectric element 74 may be damaged. Therefore, a drive waveform that does not become the resonance frequency of diaphragm 73 is set at the time of manufacturing. However, there is a possibility that air bubbles are mixed into the pressure chamber SC, the liquid storage chamber SR, or the like during printing, and when the air bubbles are mixed, the resonance frequency of the vibration plate 73 suddenly fluctuates. Therefore, the frequency of the drive waveform may coincide with the varied resonance frequency, and cracks may be generated in the vibration plate 73 or the piezoelectric element 74, thereby causing damage. If the diaphragm 73 and the piezoelectric element 74 are damaged, printing cannot be continued thereafter, and a trouble time occurs.

Therefore, in the liquid discharge apparatus 10 of the present embodiment, the drive control circuit 21 switches the operation mode according to the presence or absence of air bubbles in the internal space (the pressure chamber SC, the liquid storage chamber SR, or the like) of the liquid discharge head 26, thereby applying different drive waveforms to the piezoelectric element 74. According to the above configuration, the piezoelectric element 74 can be driven with different drive waveforms depending on the presence or absence of bubbles, and the diaphragm 73 can be vibrated. Therefore, even if the resonance frequency of the diaphragm 73 varies depending on the presence or absence of the bubble, stable ink ejection can be continuously performed regardless of the presence or absence of the bubble, and the occurrence of a failure time can be suppressed. The time point of switching the operation mode may be before the start of printing or after (during) the start of printing. When switching is performed before printing is started, if the printing time is long, the head is heated accordingly and bubbles are likely to become large, and therefore, a mode of switching according to the length of the printing time may be employed.

Fig. 4 is a diagram for explaining an operation mode of the present embodiment. As shown in fig. 4, the operation modes of the present embodiment include a first mode and a second mode in which different drive waveforms W1, W2 are applied to the piezoelectric element 74. The first mode is an operation mode in which the ink is ejected by applying the drive waveform W1 to the piezoelectric element 74. The second mode is an operation mode in which a drive waveform W2 different from the drive waveform W1 is applied to the piezoelectric element 74 to discharge ink. The drive waveform W1 of the first mode shown in fig. 4 is included in the first drive waveform signal COM1, and the drive waveform W2 of the second mode is included in the second drive waveform signal COM 2. The drive waveform W1 and the drive waveform W2 are generated at a predetermined period T, respectively. The drive waveform W1 is applied by outputting the first drive signal V1 to the piezoelectric element 74 to which the ejection of ink is instructed, and the drive waveform W2 is applied by outputting the second drive signal V2 to the piezoelectric element 74 to which the ejection of ink is instructed.

In fig. 4, the drive waveform W1 of the first mode is shown on the left side, and the drive waveform W2 of the second mode is shown on the right side. The drive waveform W1 changes from the reference potential VM to the potential VL during the period T, and after the potential VL is held for a certain period of time, changes from the potential VL, which is the minimum value of the potential, to the potential VH, which is the maximum value of the potential, and holds the potential VH for a certain period of time. After that, the potential VH is changed to the reference potential VM. The drive waveform W2 changes from the reference potential VM to the potential VL in the period T, changes from the potential VL, which is the minimum value of the potential, to the potential VH ', which is the maximum value of the potential, after the potential VL is held for a certain time, and holds the potential VH' for a certain time. Thereafter, the potential VH' is changed to the reference potential VM.

By switching from the reference potential VM to the potential VL according to the drive waveforms W1 and W2, the meniscus in the nozzle N is temporarily drawn toward the pressure chamber SC. Then, when the potential VL is changed to the potential VH or VH', the meniscus in the nozzle N moves toward the opening of the nozzle N (the opening of the nozzle N from which ink is ejected) at a time, and the ink is pushed out from the opening of the nozzle N. Further, by changing from the potential VH or VH' to the reference potential VM, the meniscus in the nozzle N is drawn toward the pressure chamber SC, whereby the ink pushed out from the opening of the nozzle N can be cut off and the ink droplets can be ejected from the opening of the nozzle N.

The drive waveform W1 and the drive waveform W2 are different waveforms. The drive waveforms W1 and W2 are waveforms that are switched, for example, whether the vibration plate 73 resonates or not depending on which of the drive waveform W1 and the drive waveform W2 is applied to the piezoelectric element 74. As described above, since the resonance frequency of the diaphragm 73 changes depending on the presence or absence of the air bubbles, for example, the drive waveform W1 is a waveform in which the frequency of the piezoelectric element 74 does not coincide with the resonance frequency of the diaphragm 73 in the case where no air bubbles are present, and the drive waveform W2 is a waveform in which the frequency of the piezoelectric element 74 coincides with the resonance frequency of the diaphragm 73 in the case where no air bubbles are present. By adopting this manner, if ink is ejected with the drive waveform W1 of the first mode in the absence of bubbles and ink is ejected with the drive waveform W2 of the second mode in the presence of bubbles, the piezoelectric element 74 can be driven with a drive waveform in which the frequency of the piezoelectric element 74 does not coincide with the resonance frequency of the vibration plate 73 in any case. Therefore, the ink can be ejected with a drive waveform in which the frequency of the piezoelectric element 74 does not match the resonance frequency of the diaphragm 73 regardless of the presence or absence of the bubble, and therefore, the occurrence of cracks in the diaphragm 73 and the piezoelectric element 74 can be suppressed.

The drive waveform W1 and the drive waveform W2 can be different waveforms by making at least one of the slope of the waveform, the maximum value of the potential, the minimum value of the potential, the amplitude of the waveform, and the frequency of the waveform different. The drive waveform W2 of fig. 4 is a waveform in which the maximum value VH' of the potential is made smaller than the drive waveform W1. According to the drive waveform W2, since the force pushing out the meniscus in the nozzle N is weaker than the drive waveform W1, the amount of ink ejected can be reduced as compared with the drive waveform W1. By varying the maximum value of the voltage of the drive waveform W2 or the like in this manner, the ejection rate of ink ejected in the presence of bubbles and the size of droplets can be varied. By changing the ejection amount of ink and the size of the droplets, the frequency of the piezoelectric element 74 can be made different from the resonance frequency of the vibration plate 73.

In addition, the slope of the waveform and the like can be changed so as not to change the ejection amount of ink and the size of the droplet. In addition, when the amount of bubbles is large, if the amplitude of the drive waveform W2 is increased, it is possible to discharge liquid droplets even if pressure fluctuations are absorbed by the bubbles. Further, by preventing the amplitudes of the drive waveforms W1 and W2 from becoming too small, it is possible to prevent the occurrence of fogging due to absorption of pressure fluctuations. The drive waveform in which the frequency of the piezoelectric element 74 does not coincide with the resonance frequency of the diaphragm 73 may be a waveform in which the frequency of the piezoelectric element 74 is shifted to the high frequency side or a waveform in which the frequency is shifted to the low frequency side.

A state signal VS indicating the state of the liquid ejection head 26 is output from the second terminal P2, which is the output terminal of the head driving circuit 262 shown in fig. 2. The state signal VS is input to a fifth terminal P5 as an input terminal of the drive control circuit 21. As for the input, as long as the second terminal P2 and the fifth terminal P5 are electrically connected, other circuit elements may be present between the two terminals. The state of the liquid discharge head 26 also changes depending on whether or not air bubbles or the like are present in the internal space of the liquid discharge head 26 (the pressure chamber SC, the liquid storage chamber SR, or the like), and therefore the state signal VS also changes. Therefore, the presence or absence of the bubble can be determined based on whether or not the state signal VS is a predetermined signal. For example, the state signal VS in the case where a bubble is present may be a predetermined signal, and the state signal in the case where a bubble is not present may not be a predetermined signal.

The determination unit 52 shown in fig. 2 also determines whether or not bubbles are present in the pressure chamber SC by the state signal VS. Specifically, the determination is made based on whether the state signal VS is a signal that does not exceed the threshold value (is a predetermined signal. The state signal VS is a signal including, for example, the cycle or amplitude of residual vibration detected by applying a predetermined drive waveform to the piezoelectric element 74. Since the period or amplitude of the residual vibration differs between the case where the air bubbles are present in the pressure chamber SC and the case where the air bubbles are not present, whether or not the air bubbles are present in the pressure chamber SC can be determined by setting the period or amplitude of the residual vibration as the state signal VS. The threshold of the state signal VS is calculated from the cycle or amplitude of the residual vibration detected when the bubble is present, and is stored in the data table C in advance. The determination unit 52 reads out the threshold from the data table C and determines the threshold. Further, since the period or amplitude of the residual vibration also changes depending on the amount of bubbles, the amount of bubbles can also be determined by providing a plurality of threshold values of the period or amplitude of the residual vibration. The state signal VS is not limited to the period or amplitude of the residual vibration, and any value may be used as the state signal VS as long as the index indicates the difference between the residual vibration in which the bubbles are present and the residual vibration in which the bubbles are not present.

The determination unit 52 determines that no bubble is present when the state signal VS does not exceed the threshold, and determines that a bubble is present when the state signal VS exceeds the threshold. When the state signal VS does not exceed the threshold (no bubble is present), the first drive waveform signal COM1 based on the first pattern is input to the head drive circuit 262, and the head drive circuit 262 applies the drive waveform W1 to the piezoelectric element 74 to perform ink ejection. On the other hand, when the state signal VS exceeds the threshold (air bubbles are present), the second drive waveform signal COM2 based on the second mode is input to the head drive circuit 262, and the head drive circuit 262 applies the drive waveform W2 to the piezoelectric element 74 to perform ink ejection.

In this manner, when it is determined that the air bubbles are present, the mode is switched from the first mode to the second mode, and the drive waveform applied to the piezoelectric element 74 of the pressure chamber SC is switched from the drive waveform W1 to the drive waveform W2. Therefore, even if the resonance frequency of the diaphragm 73 is varied by the bubbles, the ink can be ejected with a drive waveform such that the resonance of the diaphragm 73 does not occur, and therefore, the occurrence of cracks in the diaphragm 73 can be effectively suppressed. Therefore, stable liquid discharge can be continuously performed regardless of the presence or absence of the bubble, and the occurrence of a failure time can be suppressed.

Next, a method of driving the liquid ejecting apparatus 10 according to the present embodiment will be described with reference to the drawings. Fig. 5 is a flowchart showing control of the liquid ejecting apparatus 10 at the time of printing. As shown in fig. 5, in step S11, the control unit 50 detects bubbles. Specifically, the control unit 50 outputs the drive waveform signal COM including the drive waveform for bubble detection from the drive signal generation unit 40 to the head drive circuit 262. The head drive circuit 262 drives the piezoelectric element 74 with a drive waveform for bubble detection, and outputs the period or amplitude of the residual vibration to the determination unit 52 as the state signal VS.

In step S12, the determination unit 52 determines whether or not the state signal VS exceeds a threshold value. When the determination section 52 determines in step S12 that the state signal VS does not exceed the threshold, that is, when it determines that no bubble is present, the drive control circuit 21 performs control for ejecting ink in the first mode in step S13. Specifically, the head drive circuit 262 receives the first drive waveform signal COM1 and the selection signal SI in the first mode, and the head drive circuit 262 outputs the first drive signal V1 to the piezoelectric element 74 whose ejection is instructed by the selection signal SI, whereby the drive waveform W1 is applied to the piezoelectric element 74 to perform the ejection of the ink.

When the determination section 52 determines in step S12 that the state signal VS exceeds the threshold, that is, when it determines that air bubbles are present, the drive control circuit 21 performs control to eject ink in the second mode in step S14. Specifically, the head drive circuit 262 receives the second drive waveform signal COM2 and the selection signal SI in the second mode, and the head drive circuit 262 outputs the second drive signal V2 to the piezoelectric element 74 whose ejection is instructed by the selection signal SI, whereby the drive waveform W2 is applied to the piezoelectric element 74 to perform the ejection of the ink. As described above, according to the present embodiment, the piezoelectric element 74 can be driven with different drive waveforms depending on the presence or absence of bubbles in the pressure chamber SC, and the vibration plate 73 can be vibrated. Therefore, the occurrence of cracks in the vibration plate 73 and the piezoelectric element 74 can be suppressed regardless of the presence or absence of air bubbles, stable ink ejection can be continuously performed, and the occurrence of a failure time can be suppressed.

Second embodiment

A second embodiment of the present invention will be explained below. The same elements as those in the first embodiment in the functions or functions of the respective embodiments described below are denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof are appropriately omitted. Although the case where a plurality of drive waveform signals COM1 and COM2 are used is exemplified in the first embodiment, the case where a single drive waveform signal COM including a plurality of drive waveforms is used is exemplified in the second embodiment.

Fig. 6 is a diagram for explaining an operation mode of the second embodiment. As shown in fig. 6, the drive waveform signal COM of the second embodiment is a drive waveform signal common to the first mode and the second mode. In the period T of the drive waveform signal COM of fig. 6, the drive waveform W1 and the drive waveform W2 similar to those of the first embodiment are included. The selection signal SI of the second embodiment includes a first selection signal SI1 for selecting the drive waveform W1 and a second selection signal SI2 for selecting the drive waveform W2. The first selection signal SI1 and the second selection signal SI2 are generated based on the print data G.

The drive control circuit 21 according to the second embodiment also performs the control shown in fig. 5. However, in the second embodiment, when it is determined that the air bubbles do not enter the pressure chambers SC and the ink is ejected in the first mode in step S13, the first selection signal SI1 and the drive waveform signal COM based on the first mode are input to the head drive circuit 262. The head drive circuit 262 outputs the first drive signal V1 including the drive waveform W1 selected by the first selection signal SI1 to the piezoelectric element 74 instructed to eject by the first selection signal SI1, thereby applying the drive waveform W1 to the piezoelectric element 74 to perform the ejection of the ink.

When it is determined that air bubbles are present in the pressure chambers SC and ink is ejected in the first mode in step S14, the second selection signal SI2 and the drive waveform signal COM based on the second mode are input to the head drive circuit 262. The head driving circuit 262 outputs the second driving signal V2 including the driving waveform W2 selected by the second selection signal SI2 to the piezoelectric element 74 instructed to be ejected by the second selection signal SI2, thereby applying the driving waveform W2 to the piezoelectric element 74 to perform the ejection of the ink.

Similarly to the first embodiment, according to the second embodiment, the piezoelectric element 74 can be driven with different drive waveforms depending on the presence or absence of bubbles in the pressure chamber SC, so that the diaphragm 73 can vibrate. Therefore, the piezoelectric element 74 can be driven so that the vibration plate 73 does not resonate regardless of the presence or absence of the bubble, and therefore, the occurrence of the crack can be suppressed, the stable ink ejection can be continued, and the occurrence of the failure time can be suppressed.

Third embodiment

A third embodiment of the present invention will be explained below. In the third embodiment, a case where the dot size (the size of the dots of the ink ejected onto the medium 12) is changed is exemplified. Fig. 7 is a diagram for explaining an operation mode of the third embodiment. As shown in fig. 7, the third embodiment also illustrates a case where a plurality of drive waveform signals COM1 and COM2 are used, as in the first embodiment. In the period T of the first drive waveform signal COM1 of fig. 7, the drive waveform W11 of the dot size "large", the drive waveform W12 of the dot size "medium", and the drive waveform W13 of the dot size "small" are included.

In the period T of the second drive waveform signal COM2 of fig. 7, the drive waveform W21 of the dot size "large", the drive waveform W22 of the dot size "medium", and the drive waveform W23 of the dot size "small" are included. The drive waveform W11 and the drive waveform W21 of the dot size "large" are different waveforms, the drive waveform W12 and the drive waveform W22 of the dot size "medium" are different waveforms, and the drive waveform W13 and the drive waveform W23 of the dot size "small" are different waveforms. At least one of the slope, the maximum value of the potential, the minimum value of the potential, the amplitude of the waveform, and the frequency of the waveform of each of the drive waveforms W11, W12, W13 and the drive waveforms W21, W22, W23 is different.

The drive control circuit 21 according to the third embodiment also performs the control shown in fig. 5. However, in the third embodiment, when it is determined that no bubble is present in the pressure chamber SC and the ink is ejected in the first mode in step S13, the first drive selection signal COM1 and the selection signal SI based on the first mode are input to the head drive circuit 262. The head driving circuit 262 outputs the first driving signal V1 including any one of the driving waveforms W11, W12, and W13 selected by the selection signal SI to the piezoelectric element 74 instructed to discharge by the selection signal SI, thereby performing the discharge of the ink.

When it is determined that air bubbles are present in the pressure chambers Sc and ink is ejected in the second mode in step S14, the second drive waveform signal COM2 and the selection signal SI based on the second mode are input to the head drive circuit 262. The head driving circuit 262 outputs the second driving signal V2 including any one of the driving waveforms W21, W22, and W23 selected by the selection signal SI to the piezoelectric element 74 instructed to discharge by the selection signal SI, thereby performing the discharge of the ink.

According to the third embodiment, similarly to the first embodiment, even if the dot size is different, the piezoelectric element 74 can be driven with different driving waveforms depending on the presence or absence of air bubbles in the pressure chamber SC, and the vibration plate 73 can be vibrated. Therefore, the piezoelectric element 74 can be driven so that the vibration plate 73 does not resonate regardless of the presence or absence of the bubble, and therefore, the occurrence of the crack can be suppressed, the stable ink ejection can be continued, and the occurrence of the failure time can be suppressed.

Fourth embodiment

A fourth embodiment of the present invention will be explained. Although the third embodiment illustrates the case where the plurality of driving waveform signals COM1 and COM2 are used when the dot size is changed, the fourth embodiment illustrates the case where a single driving waveform signal COM including a plurality of driving waveforms is used when the dot size is changed. Fig. 8 and 9 are diagrams for explaining an operation mode of the fourth embodiment. Fig. 8 is an example of the drive waveform signal COM that is common in the first mode and the second mode. Fig. 9 is a diagram illustrating a driving waveform selected in each mode according to a dot size.

In the period T of the drive waveform signal COM of fig. 8, the drive waveforms W11, W12, W13 and the drive waveforms W21, W22, W23 are included. The shapes of the drive waveforms W11, W12, and W13 and the drive waveforms W21, W22, and W23 are the same as those in fig. 7. The period T of the drive waveform signal COM in fig. 8 corresponds to one pixel, and ink corresponding to one pixel is discharged by a drive waveform selected from the drive waveforms W11, W12, and W13 and the drive waveforms W21, W22, and W23 included in the period T. The selection signal SI of the fourth embodiment includes a first selection signal SI1 for selecting any one of the drive waveforms W11, W12, and W13, and a second selection signal SI2 for selecting any one of the drive waveforms W21, W22, and W23. The first selection signal SI1 and the second selection signal SI2 are generated based on the print data G.

The drive control circuit 21 according to the fourth embodiment also performs the control shown in fig. 5. However, in the fourth embodiment, when it is determined that no bubble is present in the pressure chamber SC and the ink is ejected in the first mode in step S13, the first selection signal SI1 and the drive waveform signal COM based on the first mode are input to the head drive circuit 262. The head drive circuit 262 outputs the first drive signal V1 including the drive waveform selected from the drive waveforms W11, W12, and W13 by the first selection signal SI1 to the piezoelectric element 74 instructed to be ejected by the first selection signal SI1, thereby performing the ejection of the ink. As shown in the first pattern of fig. 9, by the first selection signal SI1, the drive waveform W11 is selected when the dot size is "large", the drive waveform W12 is selected when the dot size is "medium", and the drive waveform W13 is selected when the dot size is "small".

When it is determined that the air bubbles are present in the pressure chamber SC and the ink is ejected in the first mode in step S14, the second selection signal SI2 and the drive waveform signal COM based on the second mode are input to the head drive circuit 262. The head driving circuit 262 outputs the second driving signal V2 including the driving waveform selected from the driving waveforms W21, W22, and W23 by the second selection signal SI2 to the piezoelectric element 74 instructed to be ejected by the second selection signal SI2, thereby performing the ejection of the ink. As shown in the second pattern of fig. 9, by the second selection signal SI2, the drive waveform W21 is selected when the dot size is "large", the drive waveform W22 is selected when the dot size is "medium", and the drive waveform W23 is selected when the dot size is "small".

According to the fourth embodiment, as in the third embodiment, even if the dot size is different, the piezoelectric element 74 can be driven with a different driving waveform depending on the presence or absence of air bubbles in the pressure chamber SC, and the vibration plate 73 can be vibrated. Therefore, the piezoelectric element 74 can be driven so that the vibration plate 73 does not resonate regardless of the presence or absence of the bubble, and therefore, the occurrence of the crack can be suppressed, the stable ink ejection can be continued, and the occurrence of the failure time can be suppressed.

Fifth embodiment

A fifth embodiment of the present invention will be explained. Although the first to fourth embodiments have exemplified the case where different drive waveforms are applied to the piezoelectric element 74 depending on the presence or absence of air bubbles in the pressure chamber SC, the fifth embodiment has exemplified the case where different drive waveforms are applied to the piezoelectric element 74 depending on the amount of air bubbles in the pressure chamber SC. The bubble amount here indicates the amount and size of bubbles in the pressure chamber SC. However, by setting the bubble amount to "0" when no bubble is present in the pressure chamber SC, the present invention can be applied not only to the case where a bubble is present but also to the case where no bubble is present.

Fig. 10 and 11 are diagrams for explaining an operation mode of the fifth embodiment. Fig. 10 is an illustration of a drive waveform signal COM that is common in the first mode and the second mode, and has the same drive waveform as the drive waveforms W11, W12, W13 of fig. 8. Fig. 11 is a diagram illustrating a driving waveform selected in each mode according to a dot size.

In the fifth embodiment, the piezoelectric element 74 is driven so that the vibration plate 73 does not resonate by defining a selectable drive waveform according to the amount of air bubbles in the pressure chamber SC. In particular, the drive waveform for selectable dot sizes is defined according to the continuous application time of the drive waveform. For example, as shown in fig. 11, the first mode (selection signal SI11) when the bubble amount is zero (no bubble is present) and the second mode when the bubble amount is not zero (bubble is present) are divided. In the second mode, the selection signal SI21 in the case of the "small" amount of air bubbles, the selection signal SI22 in the case of the "medium" amount of air bubbles, and the selection signal SI23 in the case of the "large" amount of air bubbles are divided. The amount of bubbles is not limited to three types of "small", "medium", and "large", and may be divided into two types of "small" and "large", or four or more types.

In the first pattern of fig. 11, as in the case of the fourth embodiment, the drive waveform W11 with the dot size "large", the drive waveform W12 with the dot size "medium", and the drive waveform W13 with the dot size "small" are also selectable. In contrast, in the case where the bubble amount is "small" in the second pattern of fig. 11, the drive waveform W11 for the dot size "large" and the drive waveform W13 for the dot size "small" are made selectable, and the drive waveform W12 for the dot size "medium" is limited to "unselectable" - ". When the bubble amount is "medium", the drive waveform W12 of the dot size "medium" and the drive waveform W13 of the dot size "small" are made selectable, and the drive waveform W11 of the dot size "large" is limited to "non-selectable". In the case where the bubble amount is "large", the drive waveform W11 of the dot size "large" is made selectable, and the drive waveform W12 of the dot size "medium" and the drive waveform W13 of the dot size "small" are limited to the non-selectable "-".

The drive control circuit 21 according to the fifth embodiment also performs the control shown in fig. 5. However, in the fifth embodiment, the bubble amount is detected in step S11, and the bubble amount is determined based on the state signal VS. Specifically, if a plurality of thresholds, for example, a first threshold, a second threshold, and a third threshold, are provided when the state signal VS is used, the bubble amount can be set to zero (no bubble is present) when the state signal VS does not exceed the first threshold. Further, the air bubble amount is set to "small" when the air bubble amount exceeds the first threshold but does not exceed the second threshold, the air bubble amount is set to "medium" when the air bubble amount exceeds the second threshold but does not exceed the third threshold, and the air bubble amount is set to "large" when the air bubble amount exceeds the third threshold.

When the state signal VS does not exceed the first threshold value in step S12, it is determined that the amount of bubbles is not present in the pressure chamber SC, and the drive control circuit 21 performs control to eject ink in the first mode in step S13. Specifically, the first selection signal SI11 based on the first mode and the drive waveform signal COM are input to the head drive circuit 262. The head drive circuit 262 outputs the first drive signal V1 including the drive waveform selected from the drive waveforms W11, W12, and W13 by the first selection signal SI11 to the piezoelectric element 74 instructed to be ejected by the first selection signal SI11, thereby performing the ejection of the ink.

When the state signal VS exceeds the first threshold value in step S12, the determination unit 52 determines that the amount of bubbles is present in the pressure chamber SC, and further, in step S14, the drive control circuit 21 performs control to eject ink in the second mode. In this case, the head drive circuit 262 receives the drive waveform signal COM and any one of the second selection signals SI21, SI22, and SI23 in accordance with the amount of air bubbles in the pressure chamber SC determined as described above. The head driving circuit 262 outputs the second driving signal V2 including the driving waveform selected according to the bubble amount from among the driving waveforms W21, W22, and W23 to the piezoelectric element 74 instructed to discharge by the input second selection signal SI2, thereby performing the discharge of the ink. For example, in the case where the amount of air bubbles is "small" in the second mode, the drive waveform W12 having the dot size "medium" cannot be selected, and therefore, in the pixel having the dot size "medium", the ink is ejected with, for example, the drive waveform W11 having the dot size "large" and the drive waveform W13 having the dot size "small" in place of the drive waveform W12.

As described above, in the fifth embodiment, the piezoelectric element 74 is driven so that the vibration plate 73 does not resonate by defining the driving waveform to be used in accordance with the amount of air bubbles in the pressure chamber SC. Therefore, the piezoelectric element 74 can be driven so that the vibration plate 73 does not resonate regardless of the amount of bubbles, and therefore, the occurrence of cracks can be suppressed, stable ink ejection can be continued, and the occurrence of a failure time can be suppressed. Although the fifth embodiment illustrates the case where the selectable drive waveform is limited according to the amount of bubbles in the pressure chamber SC, the present invention is not limited to this, and the resolution may be changed according to the amount of bubbles in the pressure chamber SC. For example, in fig. 11, the drive waveform may be set to the non-selectable "-" portion, or the drive waveform may be set to be selectable to improve the resolution. When the resolution is changed, the number of pixels or the period T of the drive waveform signal COM is also changed. Thus, even if the resolution is changed according to the amount of bubbles, the piezoelectric element 74 can be driven so that the vibration plate 73 does not resonate.

Although the above embodiments have exemplified the case where the ink is ejected in different drive waveforms according to the state signal VS (presence or absence of bubbles and the amount of bubbles), the user-selectable mode may be further limited. For example, the selection button of the operation mode displayed on the display unit 62 can be changed in accordance with the state signal VS from the second terminal P2 shown in fig. 2. Examples of such operation modes include a high-quality mode, a high-speed mode, a mode with complementary printing, and a mode without complementary printing. For example, when the state signal VS is a predetermined signal (when a bubble is present), one mode is displayed, and when the state signal VS is not a predetermined signal (when a bubble is not present), the other mode is displayed. Since the driving waveform used differs depending on the operation mode, the vibration plate can be kept from resonating even if the resonance frequency of the vibration plate 73 fluctuates.

Further, a different drive waveform may be applied to the piezoelectric element 74 depending on the continuous application time of the drive waveform to the piezoelectric element 74. As the continuous application time of the drive waveform is longer, the temperature of the liquid ejection head 26 increases, and the resonance frequency of the vibration plate 73 also fluctuates due to the increase in size of bubbles in the pressure chamber SC of the liquid ejection head 26. Therefore, by applying different drive waveforms to the piezoelectric element 74 according to the continuous application time of the drive waveform to the piezoelectric element 74, even if the resonance frequency of the vibration plate 73 fluctuates due to a temperature rise, cracks generated by resonance of the vibration plate 73 can be suppressed. In addition, as for the continuous application time of the drive waveform, since the temperature of the liquid ejection head 26 rises not only when ink is ejected from the nozzles N but also when a drive waveform for performing micro-vibration is applied without ejecting ink from the nozzles N, a mode may be adopted in which the time of applying such a drive waveform is added to the continuous application time. In addition, when the ink discharge amount is large, as in the flushing operation of the liquid discharge head 26 performed as the maintenance process of the nozzles N, the ink in the pressure chamber SC is easily replaced with new ink having a low temperature, and therefore, the temperature increase of the liquid discharge head 26 is alleviated. Therefore, the time for applying the drive waveform in this case may be subtracted from the continuous application time of the drive waveform.

In the liquid ejecting apparatus 10 of the above embodiment, the maximum width of the serial printable area that can be performed while the liquid ejecting head 26 is moved in the X direction is 24 inches or more and 75 inches or less, and the maximum width of the serial printable area corresponds to the medium 12 having any one of the sizes of 24 inches, 36 inches, 44 inches, and 64 inches. According to such a configuration, when the maximum width that can be printed in series is 24 inches or more and 75 inches or less, cracks caused by resonance of the vibration plate 73 can be effectively suppressed. Further, since the maximum width that can be serially printed is 24 inches or more and 75 inches or less, the total length of the signal line that transmits the drive signal or the like can be about 1m to 3m, and therefore, the impedance and the inductance of the signal line can be reduced as compared with the case where the maximum width that can be serially printed is 75 inches or more. Therefore, it is possible to suppress a malfunction or malfunction due to an overshoot (over shot) or an undershoot (under shot) of the drive signal or the like. In addition, the maximum width that can be serially printed and the size of the medium 12 are not limited to the above.

The liquid ejection head 26 of the above embodiment ejects ink with a drive waveform having a frequency of 30kHz or more. By discharging ink with a high-frequency drive waveform of 30kHz or more in this manner, printing can be performed at high speed, and thus even when the resonance frequency of the diaphragm 73 is 30kHz or more, resonance of the diaphragm 73 can be prevented. Therefore, even in the case of high-speed printing in which the frequency of the drive waveform is 30kHz or more, stable ink ejection can be achieved that is continuously performed regardless of the presence or absence of bubbles, and the occurrence of a trouble time can be suppressed. In addition, the frequency of the drive waveform is not limited to the above.

In addition, the driving waveforms of the first mode and the driving waveforms of the second mode in the above-described embodiment can be freely stored in the data table C (the storage device 203). The method of operating the liquid ejecting apparatus 10 for storing the drive waveform includes: a first step of storing the drive waveform of the first pattern in a data table C; and a second step of storing the drive waveform of the second pattern in the data table C. Accordingly, since the driving waveform of the first mode and the driving waveform of the second mode can be freely stored in the data table C, the operability is good. Further, since the ink can be ejected with the drive waveform stored in the data table C in the first mode and the second mode, it is possible to realize printing in accordance with the preference of the user while suppressing the occurrence of the trouble time.

Modification examples

The embodiments and examples illustrated above can be variously modified. Specific modifications are exemplified below. Two or more selected from the following examples and the above-described embodiments may be appropriately combined within a range not contradictory to each other.

(1) Although the above embodiment illustrates the case where the determination unit 52 determines the presence or absence of air bubbles or the amount of air bubbles in the pressure chamber SC, the present invention is not limited to this, and an embodiment may be adopted in which the presence or absence of air bubbles or the amount of air bubbles in the internal space filled with ink in the liquid ejection head 26, for example, in the liquid storage chamber SR, is determined. For example, by providing the piezoelectric element 74 on the support body 75 or the like in which the liquid storage chamber SR is formed, and setting the period or vibration of the residual vibration of the piezoelectric element 74 as the state signal VS, it is possible to determine the presence or absence of bubbles or the amount of bubbles in the liquid storage chamber SR.

The resonance frequency of the vibration plate 73 also varies depending on the presence or absence of bubbles or the amount of bubbles in the liquid storage chamber SR. Therefore, by ejecting ink by changing the drive waveform in accordance with the presence or absence of air bubbles or the amount of air bubbles in the liquid storage chamber SR, stable liquid ejection can be continuously performed regardless of the presence or absence of air bubbles, and occurrence of a failure time can be suppressed.

The position of the bubble can also be determined by the cycle or amplitude of the residual vibration of the piezoelectric element 74 in the liquid storage chamber SR and the piezoelectric element 74 in the pressure chamber SC. Therefore, different drive waveforms can be applied to the piezoelectric element 74 depending on the position of the bubble. For example, when a bubble is present in the liquid storage chamber SR, it is possible to determine which of the plurality of pressure chambers SC is close to which bubble. The resonance frequency of the vibration plate 73 is more likely to change as the piezoelectric element 74 of the pressure chamber SC is closer to the position where the air bubble is present in the liquid storage chamber SR. Therefore, the piezoelectric element 74 of the pressure chamber SC closer to the driver can be driven in the second mode. According to the above configuration, even if the resonance frequency of the vibration plate 73 changes depending on the position of the bubble, the occurrence of cracks due to the resonance of the vibration plate 73 can be suppressed.

(2) In the above-described embodiment, the case where the residual vibration is used as the state signal VS for determining whether or not the air bubbles are present in the internal space (the pressure chamber SC, the liquid storage chamber SR, and the like) filled with the ink in the liquid ejection head 26 has been exemplified, but the present invention is not limited thereto. For example, in the liquid ejection head 26, the presence or absence of bubbles and the amount of bubbles can be determined by a sensor that detects the liquid level of a bubble chamber provided in the ink flow path. In addition, when the ink is circulated in the liquid ejection head 26, the presence or absence of bubbles and the amount of bubbles can be estimated from the circulation flow rate or the non-circulation time.

(3) Although the serial head in which the carriage 24 on which the liquid ejection head 26 is mounted is repeatedly reciprocated in the X direction is illustrated in the above embodiment, the present invention can be applied to a line head in which the liquid ejection heads 26 are arranged over the entire width of the medium 12.

(4) Although the piezoelectric liquid discharge head 26 using a piezoelectric element that applies mechanical vibration to the pressure chamber has been illustrated in the above embodiment, a thermal liquid discharge head using a heating element that generates bubbles in the pressure chamber by heating may be used.

(5) The liquid ejecting apparatus 10 illustrated in the above embodiments may be a device dedicated to printing, and may be a facsimile machine, a copier, or other various devices. However, the application of the liquid ejecting apparatus 10 of the present invention is not limited to printing. For example, a liquid ejecting apparatus that ejects a solution of a color material can be used as a manufacturing apparatus for forming a color filter of a liquid crystal display device, an organic EL (Electro Luminescence) display panel, an FED (surface emitting display panel), or the like. Further, the liquid ejecting apparatus that ejects the solution of the conductive material can also be used as a manufacturing apparatus for forming the wiring or the electrode of the wiring board. Further, the present invention can also be used as a chip manufacturing apparatus for ejecting a biological organic solution, which is a kind of liquid.

Description of the symbols

10 … liquid ejection device; 12 … medium; 14 … a liquid container; 20 … control unit; 202 … control device; 203 … storage devices; 21 … driving control circuit; 22 … conveying mechanism; 24 … carriage; 26 … liquid ejection head; 260 … jet surface; 262 … head drive circuit; 264 … liquid ejecting section; 266 … discharge part; 40 … driving signal generating part; 50 … control section; 52 … judging section; 60 … operating panel; 62 … display part; 71 … flow channel substrate; 712 … opening part; 714 … branch flow paths; 716 … are in communication with the flow passage; 72 … pressure chamber base plate; 722 … opening part; 73 … vibrating plate; 74 … piezoelectric element; 742 … a first electrode; 744 … piezoelectric body; 746 … second electrode; 75 … a support; 754 … introducing into the flow channel; 76 … a nozzle plate; c … data sheet; COM … drive waveform signals; COM1 … first drive waveform signal; COM2 … second drive waveform signal; g … print data; an N … nozzle; a P1 … first terminal; a P2 … second terminal; a P3 … third terminal; an SC … pressure chamber; SI … select signal; SI1, SI11 … first select signals; second selection signals of SI2, SI21, SI22 and SI23 …; an SR … liquid retention chamber; period T …; a V … drive signal; a V1 … first drive signal; v2 … second drive signal; VL, VH' … potentials; VM … reference potential; VS … status signal; a W … drive waveform; w1, W11, W12, W13 … drive waveforms; w2, W21, W22, W23 … drive waveforms.

Claims

1. A drive control circuit for a liquid ejection device provided with a liquid ejection head that ejects a liquid by varying the pressure of an internal space filled with the liquid by a drive element,

in the drive control circuit, a voltage is applied to the drive circuit,

the liquid ejection head includes a head drive circuit having a first terminal to which a drive waveform signal having a drive waveform for driving the drive element is input and a second terminal which outputs a state signal indicating a state of the liquid ejection head,

the drive waveform signal includes a first drive waveform signal and a second drive waveform signal having different drive waveforms,

the drive control circuit inputs the first drive waveform signal to the first terminal when the state signal from the second terminal is a predetermined signal, and inputs the second drive waveform signal to the first terminal when the state signal from the second terminal is not a predetermined signal.

2. A drive control circuit for a liquid ejection device provided with a liquid ejection head that ejects a liquid by varying the pressure of an internal space filled with the liquid by a drive element,

in the drive control circuit, a voltage is applied to the drive circuit,

the liquid ejection head includes a head drive circuit having a first terminal to which a drive waveform signal having a plurality of drive waveforms for driving the drive element is input and a second terminal which outputs a state signal indicating a state of the liquid ejection head, the head drive circuit outputting a drive signal having a drive waveform selected from the drive waveform signals to the drive element,

the drive signals include a first drive signal and a second drive signal having different drive waveforms,

the drive control circuit inputs the first drive signal to the drive element when the state signal from the second terminal is a predetermined signal, and inputs the second drive signal to the drive element when the state signal from the second terminal is not a predetermined signal.

3. A drive control circuit for a liquid ejection device provided with a liquid ejection head that ejects a liquid by varying the pressure of an internal space filled with the liquid by a drive element,

in the drive control circuit, a voltage is applied to the drive circuit,

the liquid ejection head includes a head drive circuit having a first terminal to which a drive waveform signal having a plurality of drive waveforms for driving the drive element is input, a second terminal to which a state signal indicating a state of the liquid ejection head is output, and a third terminal to which a selection signal for selecting a drive waveform to be applied to the drive element from among the drive waveform signals is input,

the selection signals comprise a first selection signal and a second selection signal for selecting different drive waveforms,

the drive control circuit inputs the first selection signal to the third terminal when the state signal from the second terminal is a predetermined signal, and inputs the second selection signal to the third terminal when the state signal from the second terminal is not the predetermined signal.

4. The drive control circuit according to any one of claim 1 to claim 3,

the different driving waveforms are waveforms of the voltage signals, and at least one of a slope of the waveforms, a maximum value of the potential, a minimum value of the potential, an amplitude of the waveforms, and a frequency of the waveforms is different.

5. The drive control circuit according to any one of claim 1 to claim 3,

the liquid ejection head includes:

the drive element;

a pressure chamber;

a diaphragm which is disposed between the pressure chamber and the driving element and which constitutes a wall surface of the internal space and which vibrates by the driving element,

the different drive waveform is a waveform in which the presence or absence of resonance of the diaphragm is switched.

6. The drive control circuit according to any one of claim 1 to claim 3,

the liquid ejecting apparatus includes a display unit that displays an operation mode of the liquid ejecting apparatus,

and changing the operation mode displayed on the display unit according to the state signal.

7. The drive control circuit according to any one of claim 1 to claim 3,

the different drive waveforms are applied to the drive element in accordance with the amount of air bubbles within the internal space of the liquid ejection head.

8. The drive control circuit according to any one of claim 1 to claim 3,

applying the different drive waveform to the drive element in accordance with the successive application times of the drive waveform to the drive element.

9. The drive control circuit of claim 8,

the different drive waveforms are applied to the drive element in accordance with the position of bubbles contained in the internal space of the liquid ejection head.

10. The drive control circuit according to any one of claim 1 to claim 3,

the maximum width of the liquid ejecting apparatus that can be printed in series is 24 inches or more and 75 inches or less.

11. The drive control circuit of claim 10,

the maximum width printable in series as the liquid ejection device corresponds to a medium of any one of 24 inches, 36 inches, 44 inches, and 64 inches.

12. The drive control circuit according to any one of claim 1 to claim 3,

the liquid discharge head discharges the liquid with a drive waveform having a frequency of 30kHz or more.

13. A liquid ejecting apparatus includes:

a liquid ejection head that ejects liquid by varying a pressure of an internal space filled with the liquid by a driving element;

a drive control circuit that applies a drive waveform to the drive element,

the drive control circuit detects an amount of air bubbles in an internal space of the liquid ejection head, and switches the drive waveform applied to the drive element according to the detected amount of air bubbles.

14. A liquid ejection head ejects a liquid by varying a pressure of an internal space filled with the liquid by a drive element to which a drive waveform is applied from a drive control circuit,

in the liquid ejection head,

15. A method of driving a liquid discharge apparatus,

the liquid ejecting apparatus includes:

a drive control circuit that applies a drive waveform to the drive element,

16. A method of driving a liquid discharge apparatus,

the liquid ejecting apparatus includes:

a drive control circuit that switches a first mode and a second mode, which are operation modes in which different drive waveforms are applied to the drive element, according to an amount of air bubbles in an internal space of the liquid ejection head;

a storage device that stores the drive waveform,

the driving method includes:

a first step of storing the drive waveform of the first pattern in the storage device;

and a second step of storing the drive waveform of the second pattern in the storage device.