Liquid discharge system, server, and control method of liquid discharge system

Abstract

A liquid ejecting system capable of detecting deterioration of displacement of a piezoelectric element with good precision, a server, and a control method of the liquid ejecting system are provided. The liquid ejecting system includes a piezoelectric element that is displaced based on a drive signal to cause a liquid to be ejected, a drive signal output circuit that outputs the drive signal, a measurement circuit that measures a first electrostatic capacitance of the piezoelectric element, and a determination circuit that determines a deterioration state of the piezoelectric element based on the first electrostatic capacitance.

Description

TECHNICAL FIELD

[0001] The present application relates to a liquid ejection system, a server, and a control method of a liquid ejection system. BACKGROUND

[0002] In a liquid ejection system that ejects liquid, a liquid ejection system such as an inkjet printer is known that generates pressure in a pressure generating chamber by utilizing displacement of a piezoelectric element, thereby ejecting liquid from a nozzle that communicates with the pressure generating chamber, and forms a desired image by causing the ejected liquid to land on a medium. In such a liquid ejection system, a desired image is formed on a medium by repeatedly driving the piezoelectric element. Therefore, the displacement amount of the piezoelectric element gradually decreases with repeated driving, and the ejection amount of liquid ejected from the nozzle also decreases in association with the decrease in the displacement amount of the piezoelectric element. Such a decrease in the ejection amount of liquid can cause the quality of the image formed on the medium to deteriorate.

[0003] In view of such a problem, in Patent Literature 1, the voltage value of a drive signal that drives the piezoelectric element is corrected based on the count value of the number of times of ejection of liquid, thereby reducing the likelihood of a decrease in the displacement amount of the piezoelectric element, and reducing the likelihood of a decrease in the ejection amount of liquid ejected from the nozzle.

[0004] However, the decrease in the displacement amount of the piezoelectric element is caused not only by the number of times of driving of the piezoelectric element, but also by a plurality of main causes such as the use environment and the voltage value of the supply voltage. Therefore, the technology described in Patent Literature 1 that corrects the voltage value of a drive signal that drives the piezoelectric element based on the count value of the number of times of ejection of liquid is not sufficient, and there is room for improvement.

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2009-066948 SUMMARY

[0006] One embodiment of the liquid ejection system according to the present application includes:

[0007] a piezoelectric element that is displaced based on a drive signal to cause liquid to be ejected;

[0008] a drive signal output circuit that outputs the drive signal;

[0009] a measurement circuit that measures a first electrostatic capacitance of the piezoelectric element;

[0010] a determination circuit that determines a deterioration state of the piezoelectric element based on the first electrostatic capacitance.

[0011] One embodiment of a server according to the present application is provided so as to be capable of communicating with a liquid ejecting apparatus including a piezoelectric element that is displaced on the basis of a drive signal to cause liquid to be ejected, and the server includes:

[0012] a receiving section that receives electrostatic capacitance information including an electrostatic capacitance of the piezoelectric element measured by a measurement circuit;

[0013] a determination circuit that determines a deterioration state of the piezoelectric element on the basis of the electrostatic capacitance information;

[0014] a transmission section that transmits determination result information including a determination result of the determination circuit.

[0015] One embodiment of a control method of a liquid ejecting system according to the present application is,

[0016] the liquid ejecting system includes:

[0017] a piezoelectric element that is displaced on the basis of a drive signal to cause liquid to be ejected;

[0018] a drive signal output circuit that outputs the drive signal,

[0019] In the control method of the liquid ejecting system, there are:

[0020] a step of measuring an electrostatic capacitance of the piezoelectric element;

[0021] a step of determining a deterioration state of the piezoelectric element on the basis of the electrostatic capacitance. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a view that shows a structure of a liquid ejecting system.

[0023] Figure 2 is a view that shows one example of a signal waveform of a drive signal COM.

[0024] Figure 3 is a view that shows one example of a schematic structure of an ejecting section.

[0025] Figure 4 is a view that shows one example of a structure of a measurement circuit.

[0026] Figure 5 is a view that is used to describe one example of an operation of a measurement circuit.

[0027] Figure 6 is a view that shows one example of a control method of a liquid ejecting system.

[0028] Figure 7This diagram illustrates the structure of the liquid ejection system according to the second embodiment.

[0029] Figure 8 This is a diagram illustrating an example of the structure of the measurement circuit in the second embodiment.

[0030] Figure 9 This diagram illustrates the structure of the liquid ejection system according to the third embodiment. Detailed Implementation

[0031] Preferred embodiments of the present invention will now be described using the accompanying drawings. The drawings are provided for ease of explanation. Furthermore, the embodiments described below are not intended to unduly limit the scope of the invention as defined in the claims. Additionally, not all structures described herein are necessarily essential structural elements of the present invention.

[0032] 1. First Implementation Method

[0033] Functional structure and operation of the liquid ejection system SY

[0034] Figure 1 This diagram illustrates the structure of the liquid ejection system SY according to the first embodiment. Figure 1 As shown, the liquid ejection system SY of the first embodiment includes a liquid ejection device 1 for ejecting liquid. Although the liquid ejection device 1 of the first embodiment is described as an inkjet printer that forms a desired image on a medium by ejecting ink, which is an example of liquid, into the medium, it is not limited to this. The liquid ejection device 1 can also be a color material ejection device used in the manufacture of color filters for liquid crystal displays, an electrode material ejection device used in the electrode formation of organic EL displays and surface-emitting displays, a bio-organic material ejection device used in the manufacture of biochips, etc.

[0035] like Figure 1 As shown, the liquid ejection device 1 includes a control circuit 100, a notification unit 110, a drive signal output circuit 50, a drive signal selection control circuit 210, n selection circuits 230, a measurement circuit 300, a judgment circuit 310, a life estimation circuit 320, a correction value calculation circuit 330, and n ejection units 600.

[0036] In the control circuit 100, image data, including information about an image formed on a medium, is input from an external device (not shown) located outside the liquid ejection device 1. Furthermore, the control circuit 100 controls various structures of the liquid ejection device 1 based on the input image data.

[0037] Specifically, the control circuit 100 generates the ejection data signal DATA based on the image data input from the external device, and outputs it to the drive signal selection control circuit 210. The drive signal selection control circuit 210 generates the selection signals S corresponding to the n selection circuits 230 respectively based on the ejection data signal DATA at the timing specified by the ejection data signal DATA, and outputs them to the corresponding selection circuits 230. That is, in the ejection data signal DATA, there are included a signal specifying the timing at which the drive signal selection control circuit 210 outputs the selection signals S, and a signal specifying the logic levels of the selection signals S corresponding to the n selection circuits 230 respectively.

[0038] Further, the control circuit 100 generates the base drive signal dA and outputs it to the drive signal output circuit 50. The drive signal output circuit 50 converts the base drive signal dA of the input digital signal into an analog signal, and generates the drive signal COM by amplifying the converted analog signal. Also, the drive signal output circuit 50 outputs the generated drive signal COM to the n selection circuits 230. That is, the control circuit 100 outputs the base drive signal dA specifying the signal waveform of the drive signal COM to the drive signal output circuit 50, the drive signal output circuit 50 generates the drive signal COM by amplifying the signal waveform specified by the input base drive signal dA, and outputs it to the n selection circuits 230. In other words, the liquid ejection system SY is provided with the drive signal output circuit 50 outputting the drive signal COM.

[0039] Such a drive signal output circuit 50 can be a structure capable of amplifying the analog signal obtained based on the base drive signal dA, and is constituted, for example, in a manner including an amplification circuit such as a class A amplification circuit, a class B amplification circuit, a class AB amplification circuit, or a class D amplification circuit. Further, the base drive signal dA output by the control circuit 100 can be an analog signal as long as it can specify the signal waveform of the drive signal COM output by the drive signal output circuit 50.

[0040] Here, one example of the signal waveform of the drive signal COM output by the drive signal output circuit 50 will be described. Figure 2 A diagram showing one example of the signal waveform of the drive signal COM. Figure 2The illustrated drive signal COM contains a trapezoidal waveform Adp for each predetermined period T. The trapezoidal waveform Adp includes a period during which the voltage is constant at a voltage vc, a period during which the voltage is constant at a voltage vb that is smaller in voltage value than the voltage vc following the period during which the voltage is constant at the voltage vc, a period during which the voltage is constant at a voltage vt that is larger in voltage value than the voltage vc following the period during which the voltage is constant at the voltage vb, and a period during which the voltage is constant at the voltage vc following the period during which the voltage is constant at the voltage vt. That is, the drive signal output circuit 50 outputs the drive signal COM containing the trapezoidal waveform Adp whose voltage value starts at the voltage vc and changes to the voltage vb, vt, and then ends at the voltage vc.

[0041] Here, in the following description, the potential difference between the voltage vt and the voltage vb will be sometimes referred to as the amplitude of the drive signal COM. In addition, the signal waveform of the drive signal COM output by the drive signal output circuit 50 is not limited to Figure 2 The illustrated shape, the drive signal output circuit 50 can also output the drive signal COM containing various signal waveforms corresponding to the physical properties of the ink ejected toward the medium, or the frequency of the drive signal COM, the conveyance speed of the medium, and the like.

[0042] Returning to Figure 1 In the n selection circuits 230, the selection signal S output by the drive signal selection control circuit 210 and the drive signal COM output by the drive signal output circuit 50 are input. Further, the n selection circuits 230 set the trapezoidal waveform Adp of the drive signal COM to selected or deselected based on the logic level of the input selection signal S, and thereby generate and output the drive signal VOUT. Specifically, in a case where the selection circuit 230 selects the trapezoidal waveform Adp of the drive signal COM based on the logic level of the selection signal S, the selection circuit 230 outputs the drive signal VOUT containing the trapezoidal waveform Adp. On the other hand, in a case where the selection circuit 230 sets the trapezoidal waveform Adp of the drive signal COM to deselected based on the logic level of the selection signal S, the selection circuit 230 outputs the drive signal VOUT not containing the trapezoidal waveform Adp. At this time, in the output terminal of the selection circuit 230, the voltage value constant at the voltage Vc immediately before and held by the capacitance component of the piezoelectric element 60 described later is held. That is, in a case where the selection circuit 230 sets the trapezoidal waveform Adp of the drive signal COM to deselected based on the logic level of the selection signal S, the selection circuit 230 outputs the drive signal VOUT whose voltage value is constant at the voltage Vc.

[0043] The n ejection sections 600 each have a piezoelectric element 60, which is provided corresponding to the n selection circuits 230. In one end of the piezoelectric element 60 possessed by each of the n ejection sections 600, a drive signal VOUT output by the corresponding selection circuit 230 is supplied. Further, in the other end of the piezoelectric element 60 possessed by each of the n ejection sections 600, a voltage Vss is commonly supplied. Moreover, the piezoelectric element 60 possessed by each of the n ejection sections 600 is driven by a potential difference between the drive signal VOUT supplied to the one end and the voltage Vss supplied to the other end. An amount of ink corresponding to the driving of the piezoelectric element 60 is ejected from the ejection section 600. Here, the voltage Vss supplied to the other end of the piezoelectric element 60 is a voltage signal that becomes a reference for the driving of the piezoelectric element 60, and can be, for example, a voltage signal that is constantly at a ground potential, or a voltage signal whose voltage value is constantly at 5.5 V or 6 V.

[0044] Here, a specific example of the structure of the ejection section 600 having the piezoelectric element 60 is described. Figure 3 A diagram showing an example of the schematic structure of one of the n ejection sections 600. Further, in Figure 3 , in addition to the ejection section 600, a nozzle plate 632, a liquid reservoir 641, and a supply port 661 are illustrated. As Figure 3 indicated, the ejection section 600 includes the piezoelectric element 60, a vibration plate 621, a cavity 631, and a nozzle 651.

[0045] The piezoelectric element 60 includes a piezoelectric body 601 and electrodes 611, 612. Also, in the piezoelectric element 60, the electrodes 611, 612 are located at positions across the piezoelectric body 601. Such a piezoelectric element 60 is driven in a manner that the central portion is displaced in the up-and-down direction, in accordance with a potential difference between a voltage value of a signal supplied to the electrode 611 and a voltage value of a signal supplied to the electrode 612. Specifically, a driving signal VOUT is supplied in the electrode 611 as one end, and a voltage Vss is supplied in the electrode 612 as the other end. Also, when the voltage value of the driving signal VOUT supplied to the electrode 611 changes, the potential difference between the driving signal VOUT supplied to the electrode 611 and the voltage Vss supplied to the electrode 612 changes. As a result, the piezoelectric element 60 is driven in a manner that the central portion is displaced in the up-and-down direction. On the other hand, when the voltage value of the driving signal VOUT supplied to the electrode 611 does not change, the potential difference between the driving signal VOUT supplied to the electrode 611 and the voltage Vss supplied to the electrode 612 does not change. As a result, the displacement of the central portion of the piezoelectric element 60 is maintained in a certain state. That is, in a case where the driving signal VOUT including the trapezoidal waveform Adp in which the voltage value changes is supplied to the electrode 611, the piezoelectric element 60 is driven, and in a case where the driving signal VOUT in which the voltage value is constant at the voltage Vc is supplied to the electrode 611, the piezoelectric element 60 is not driven.

[0046] The vibration plate 621 is located Figure 3 below the piezoelectric element 60. In other words, the piezoelectric element 60 is formed on the face above Figure 3 in the vibration plate 621. Such a vibration plate 621 is displaced in the up-and-down direction in conjunction with the driving of the piezoelectric element 60.

[0047] A cavity 631 is provided below Figure 3 in the vibration plate 621. In the cavity 631, ink is supplied from an ink reservoir 641. Further, in the ink reservoir 641, ink stored in an unillustrated ink cartridge or the like possessed by the liquid ejecting device 1 is introduced via a supply port 661. The internal volume of such a cavity 631 is enlarged or reduced in conjunction with the displacement of the vibration plate 621 in the up-and-down direction. That is, the vibration plate 621 functions as a diaphragm that changes the internal volume of the cavity 631, and the cavity 631 functions as a pressure chamber that changes the pressure in conjunction with the displacement of the vibration plate 621 in the up-and-down direction.

[0048] The nozzle 651 is an opening provided in the nozzle plate 632, and communicates with the cavity 631. Further, when the internal volume of the cavity 631 changes, the internal pressure of the cavity 631 changes in accordance with the change in the internal volume, so that the ink filled in the inside of the cavity 631 is ejected from the nozzle 651.

[0049] In the ejection section 600 configured in the above-described manner, in a case where the piezoelectric element 60 is driven in a manner that it is deflected in the upward direction, the vibration plate 621 is displaced in the upward direction. Thereby, the internal volume of the cavity 631 expands, as a result of which the ink stored in the reservoir 641 is sucked into the cavity 631. On the other hand, in a case where the piezoelectric element 60 is driven in a manner that it is deflected in the downward direction, the vibration plate 621 is displaced in the downward direction. Thereby, the internal volume of the cavity 631 contracts, as a result of which the ink stored in the cavity 631 is ejected from the nozzle 651 in an amount corresponding to the degree of contraction of the internal volume of the cavity 631.

[0050] Specifically, during a period in which the driving signal VOUT having a voltage value constant at the voltage Vc is supplied to the electrode 611 of the piezoelectric element 60, the piezoelectric element 60 is held in a certain displacement. Therefore, the ink is not ejected from the nozzle 651 corresponding to the piezoelectric element 60. Thereafter, when the voltage value of the driving signal VOUT supplied to the electrode 611 of the piezoelectric element 60 changes from the voltage vc to the voltage vb, the piezoelectric element 60 is driven in a manner that it is displaced in the upward direction of the arrow A in accordance with the change in the voltage value of the driving signal VOUT. Thereby, the vibration plate 621 is displaced in the upward direction of the arrow A, and the internal volume of the cavity 631 expands. As a result, the ink stored in the reservoir 641 is sucked into the cavity 631. Figure 3 Figure 3 Thereafter, when the voltage value of the driving signal VOUT supplied to the electrode 611 of the piezoelectric element 60 changes from the voltage vb to the voltage vt, the piezoelectric element 60 is driven in a manner that it is displaced in the downward direction of the arrow B in accordance with the change in the voltage value of the driving signal VOUT. Thereby, the vibration plate 621 is displaced in the downward direction of the arrow B, and the internal volume of the cavity 631 contracts. As a result, the ink stored in the cavity 631 is ejected from the nozzle 651. Figure 3 Figure 3 Thereafter, when the voltage value of the driving signal VOUT supplied to the electrode 611 of the piezoelectric element 60 changes from the voltage vb to the voltage vt, the piezoelectric element 60 is driven in a manner that it is displaced in the downward direction of the arrow B in accordance with the change in the voltage value of the driving signal VOUT. Thereby, the vibration plate 621 is displaced in the downward direction of the arrow B, and the internal volume of the cavity 631 contracts. As a result, the ink stored in the cavity 631 is ejected from the nozzle 651.

[0051] ​​As described above, the piezoelectric element 60 is driven in accordance with a change in the voltage value of the drive signal VOUT supplied to the electrode 611. Also, the ejection section 600 ejects ink from the nozzle 651 in an amount corresponding to the amount of driving of the piezoelectric element 60. In other words, the piezoelectric element 60 is displaced based on the drive signal VOUT obtained from the drive signal COM, and ink is ejected. At this time, the amount of driving, which is the amount of displacement of the piezoelectric element 60, and the amount of ejection of ink affect the characteristics of the piezoelectric element 60, and the respective voltage values of the voltages vc, vt, and vb supplied to the piezoelectric element 60.

[0052] In addition, the piezoelectric element 60 is only required to be a structure that can be driven in accordance with the voltage value of the supplied drive signal VOUT, and that ejects ink from the corresponding nozzle 651 by being driven, and is not limited to the structure shown as one example. Figure 1

[0053] Returning to Figure 1 , the measurement circuit 300 acquires at least one voltage value of the n piezoelectric elements 60 as a detection voltage Cc. Specifically, the measurement circuit 300 acquires the voltage value of at least one electrode 611 of the n piezoelectric elements 60 as the detection voltage Cc by being inputted with an enable signal EN that sets the detection of the voltage value as active from the control circuit 100. Also, the measurement circuit 300 generates a detection signal Cap corresponding to the electrostatic capacitance of the piezoelectric element 60 based on the acquired detection voltage Cc, and outputs it to the judgment circuit 310. That is, the measurement circuit 300 measures the electrostatic capacitance of the piezoelectric element 60, and outputs the detection signal Cap corresponding to the electrostatic capacitance. In addition, the details of the measurement circuit 300 are described later.

[0054] ​Here, the measurement of the electrostatic capacitance by the measurement circuit 300 is not limited to the case where the measurement circuit 300 directly measures the electrostatic capacitance of the piezoelectric element 60 itself, but includes the case where a physical quantity that varies depending on the value of the electrostatic capacitance is measured. Specifically, the measurement circuit 300 can also measure the time required for charging the piezoelectric element 60 that varies depending on the electrostatic capacitance of the piezoelectric element 60 by acquiring the voltage value of the piezoelectric element 60 in the case where a constant current or voltage is supplied to the piezoelectric element 60 as the electrostatic capacitance of the piezoelectric element 60, and output the measurement result as the detection signal Cap. Further, the measurement circuit 300 can also measure the time required for discharging the charge accumulated in the piezoelectric element 60 that varies depending on the electrostatic capacitance of the piezoelectric element 60 by acquiring the voltage value of the piezoelectric element 60 in the case where the charge accumulated in the piezoelectric element 60 is discharged as the electrostatic capacitance of the piezoelectric element 60, and output the measurement result as the detection signal Cap. Furthermore, the measurement circuit 300 can also output, as the detection signal Cap, the voltage value of the charging voltage to the piezoelectric element 60 within a certain time that varies depending on the electrostatic capacitance of the piezoelectric element 60 as the electrostatic capacitance of the piezoelectric element 60.

[0055] In addition, although the case where the measurement circuit 300 detects the voltage value of one piezoelectric element 60 is exemplified in Figure 4 , the measurement circuit 300 can also detect the voltage values of a plurality of piezoelectric elements 60. That is, the number of piezoelectric elements 60 whose electrostatic capacitances are measured by the measurement circuit 300 is not limited to one, but can be plural. Further, in the case where the measurement circuit 300 measures the electrostatic capacitances of a plurality of piezoelectric elements 60, the measurement circuit 300 can measure the electrostatic capacitances of the plurality of piezoelectric elements 60 individually, or can measure the synthetic electrostatic capacitance of the plurality of piezoelectric elements 60.

[0056] The detection signal Cap is input to the determination circuit 310. The determination circuit 310 determines the deterioration state of the piezoelectric element 60 on the basis of the input detection signal Cap. For example, the determination circuit 310 can determine the deterioration state of the piezoelectric element 60 in accordance with the value of the electrostatic capacity of the piezoelectric element 60 obtained on the basis of the input detection signal Cap, or the determination circuit 310 can calculate the rate of change of the electrostatic capacity of the piezoelectric element 60 on the basis of the electrostatic capacity of the piezoelectric element 60 obtained on the basis of the input detection signal Cap and the initial value of the electrostatic capacity of the piezoelectric element 60, and determine the deterioration state of the piezoelectric element 60 on the basis of the calculated rate of change. Further, the determination circuit 310 classifies the deterioration state of the piezoelectric element 60 into, for example, a normal level, a sub-normal level, a slight abnormality level, a moderate abnormality level, and a severe abnormality level on the basis of the determination result. Thereafter, the determination circuit 310 generates a state signal Cst including information of the level as the determination result of the deterioration state of the piezoelectric element 60, and outputs it to the life estimation circuit 320 and the correction value calculation circuit 330. Note that the classification of the level in the determination circuit 310 is not limited to the above-described classification.

[0057] The life estimation circuit 320 estimates the life of the piezoelectric element 60 on the basis of the input state signal Cst. For example, the life estimation circuit 320 estimates that the piezoelectric element 60 has sufficient life when the level of the deterioration state obtained on the basis of the input state signal Cst is the normal level, the sub-normal level, or the slight abnormality level. Further, the life estimation circuit 320 estimates that the piezoelectric element 60 will soon reach the life when the level of the deterioration state obtained on the basis of the input state signal Cst is the moderate abnormality level. Further, the life estimation circuit 320 estimates that the piezoelectric element 60 has reached the life when the level of the deterioration state obtained on the basis of the input state signal Cst is the severe abnormality level. Further, the life estimation circuit 320 generates a life notification signal El including information of the estimated life of the piezoelectric element 60, and outputs it to the control circuit 100.

[0058] When the control circuit 100 receives the life notification signal El from the life estimation circuit 320, which contains information indicating that the piezoelectric element 60 will soon reach the end of its life or has reached the end of its life, the control circuit 100 generates a notification signal Inf for notifying a message indicating that the piezoelectric element 60 will soon reach the end of its life or has reached the end of its life to the user, and outputs it to the notification section 110. The notification section 110 notifies the information on the life of the piezoelectric element 60 based on the notification signal Inf input thereto. That is, the liquid ejecting system SY is provided with: the life estimation circuit 320 that estimates the life of the piezoelectric element 60 based on the deterioration state of the piezoelectric element 60 judged by the judgment circuit 310; and the notification section 110 that notifies the information on the life estimated by the life estimation circuit 320.

[0059] The correction value calculation circuit 330 judges whether or not to correct the voltage value of the drive signal COM based on the state signal Cst input thereto. Specifically, the correction value calculation circuit 330 judges that the voltage value of the drive signal COM does not need to be corrected when the level of the deterioration state obtained based on the state signal Cst input thereto is the normal level or the sub-normal level. Further, the correction value calculation circuit 330 generates a correction signal Cv for correcting the voltage value of the drive signal COM by the amount of the voltage vl and outputs it to the control circuit 100 when the level of the deterioration state obtained based on the state signal Cst input thereto is the slight abnormal level. Further, the correction value calculation circuit 330 generates a correction signal Cv for correcting the voltage value of the drive signal COM by the amount of the voltage v2, which is larger than the voltage vl, and outputs it to the control circuit 100 when the level of the deterioration state obtained based on the state signal Cst input thereto is the moderate abnormal level. Further, the correction value calculation circuit 330 generates a correction signal Cv for correcting the voltage value of the drive signal COM by the amount of the voltage v3, which is larger than the voltage v2, and outputs it to the control circuit 100 when the level of the deterioration state obtained based on the state signal Cst input thereto is the severe abnormal level. In addition, the correction value calculation circuit 330 can generate a correction signal Cv for correcting the drive signal COM in such a manner that the output of the drive signal COM is stopped and outputs it to the control circuit 100 when the level of the deterioration state obtained based on the state signal Cst input thereto is the severe abnormal level.

[0060] The control circuit 100 corrects the base drive signal dA in accordance with the correction signal Cv input from the correction value calculation circuit 330. Thereby, the voltage value of the drive signal COM generated on the basis of the base drive signal dA is corrected. Specifically, as the correction of the base drive signal dA corresponding to the correction signal Cv input from the correction value calculation circuit 330, the control circuit 100 can also correct in a manner that the voltage value of the voltage vt of the trapezoidal waveform Adp included in the drive signal COM is increased, and can also correct in a manner that the amplitude of the drive signal COM is increased. That is, the correction value calculation circuit 330 and the control circuit 100 together correct the voltage value of the drive signal COM on the basis of the state signal Cst corresponding to the detection signal Cap.

[0061] As described above, the liquid ejection system SY of the first embodiment is provided with: the piezoelectric element 60 that performs displacement based on the drive signal VOUT obtained by the drive signal COM to cause ink to be ejected; the drive signal output circuit 50 that outputs the drive signal COM; the measurement circuit 300 that measures the electrostatic capacitance of the piezoelectric element 60; the judgment circuit 310 that judges the deterioration state of the piezoelectric element 60 on the basis of the electrostatic capacitance. Also, the liquid ejection system SY is provided with: the correction value calculation circuit 330 and the control circuit 100 that correct the voltage value of the drive signal COM on the basis of the deterioration state of the piezoelectric element 60 judged by the judgment circuit 310; the life span estimation circuit 320 that estimates the life span of the piezoelectric element 60 on the basis of the deterioration state judged by the judgment circuit 310; the notification section 110 that notifies information of the life span of the piezoelectric element 60 estimated by the life span estimation circuit 320.

[0062] Here, in the liquid ejection system SY in which the piezoelectric element 60 is driven by the drive signal COM and ink is ejected by the driving of the piezoelectric element 60, there is a known phenomenon in which the displacement amount of the piezoelectric element deteriorates due to continuous driving of the piezoelectric element or the like. Heretofore, for the deterioration of the displacement amount occurring in such a piezoelectric element, the deterioration of the drive signal occurring in the piezoelectric element has been compensated for by counting the number of times the piezoelectric element is driven by the drive signal and correcting the voltage value of the drive signal on the basis of the count result. However, the deterioration of the displacement amount occurring in the piezoelectric element not only affects the number of times the piezoelectric element is driven, but also affects the driving conditions such as the driving time of the piezoelectric element 60, the voltage value of the drive signal COM supplied to the piezoelectric element 60, and the ambient temperature of the piezoelectric element 60. Therefore, in the existing method of counting the number of times the piezoelectric element is driven by the drive signal and correcting the drive signal, it is difficult to appropriately judge the deterioration of the displacement amount of the piezoelectric element.

[0063] In view of the above, the present inventors focused on the fact that the deterioration of the displacement amount of the piezoelectric element has a correlation with the change in the polarization of the piezoelectric element, and the liquid ejection system SY realizes a technique of detecting the deterioration of the change amount of the piezoelectric element 60 under conditions that do not depend on the driving conditions of the piezoelectric element 60, by measuring the electrostatic capacitance of the piezoelectric element 60 by the measurement circuit 300, and judging the deterioration state of the piezoelectric element 60 based on the electrostatic capacitance of the piezoelectric element 60 measured by the measurement circuit 300 by the judgment circuit 310.

[0064] Further, the liquid ejection system SY of the first embodiment is provided with a correction value calculation circuit 330 that corrects the voltage value of the drive signal COM based on the deterioration state of the piezoelectric element 60 judged by the judgment circuit 310. Thus, even in the case where the displacement amount of the piezoelectric element 60 has deteriorated, it is possible to reduce the possibility that the ejection amount of the ejected liquid varies. That is, it is possible to improve the ejection precision of the ink in the liquid ejection system SY.

[0065] Further, since the decrease in the electrostatic capacitance of the piezoelectric element 60 is caused by the continuous driving of the piezoelectric element 60, the electrostatic capacitance of the piezoelectric element 60 also decreases at the end of the life of the piezoelectric element 60. In the liquid ejection system SY of the first embodiment, by being provided with the life estimation circuit 320 that estimates the life of the piezoelectric element 60 based on the deterioration state of the piezoelectric element 60 judged by the judgment circuit 310, and the notification section 110 that notifies the information of the life of the piezoelectric element 60 estimated by the life estimation circuit 320, it is possible to notify the user of the life of the piezoelectric element 60 and the liquid ejection system SY at an appropriate timing, and further, it is possible to improve the convenience of the user.

[0066] Structure and operation of the measurement circuit

[0067] Here, one example of the specific structure and operation of the measurement circuit 300 that measures the electrostatic capacitance of the piezoelectric element 60 will be described. Figure 4 A diagram showing one example of the structure of the measurement circuit 300. As shown in Figure 5 The measurement circuit 300 has a current source 301 that outputs a constant current, a switch 302 that switches the electrical connection between the current source 301 and the piezoelectric element 60, a comparison circuit 303 that is electrically connected to the piezoelectric element 60, and a timer circuit 304 that measures the charging time Tch of the piezoelectric element 60 based on the output of the comparison circuit 303.

[0068] A voltage Vddl is supplied to the current source 301. Also, the current source 301 generates and outputs a current Icnt having a constant current value based on the voltage Vddl. As such a current source 301, for example, a combination of one or more transistors or a constant current zener diode or the like can be used.

[0069] One end of the switch 302 is electrically connected to the output of the current source 301, and the other end is electrically connected to the electrode 611 of the piezoelectric element 60. Also, the on / off state of one end and the other end of the switch 302 is switched based on an enable signal EN input to the control end. Specifically, in a case where the enable signal EN that makes the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 active and the enable signal EN that makes the detection of the detection voltage Cc of the piezoelectric element 60 active are input to the control end of the switch 302, one end and the other end of the switch 302 are controlled to be in the on state, and in a case where the enable signal EN that does not make the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 active and the enable signal EN that does not make the detection of the detection voltage Cc of the piezoelectric element 60 active are input to the control end of the switch 302, one end and the other end of the switch 302 are controlled to be in the off state. That is, the switch 302 controls the supply of the current Icnt to the piezoelectric element 60 by the enable signal EN.

[0070] A voltage Vdd2 is supplied to the high potential side of the power supply terminal of the comparison circuit 303, and a voltage Vss is input to the low potential side of the power supply terminal of the comparison circuit 303. Further, one input end of the comparison circuit 303 is electrically connected to the electrode 611 of the piezoelectric element 60, and a reference voltage Vref is input to the other input end of the comparison circuit 303. Also, the comparison circuit 303 outputs an output voltage Cp of the H level when the voltage value of the electrode 611 of the piezoelectric element 60 input to one input end and the detection voltage Cc are higher than the reference voltage Vref, and outputs an output voltage Cp of the L level when the detection voltage Cc is equal to or lower than the reference voltage Vref.

[0071] The output voltage Cp output by the comparison circuit 303 is input to the timer circuit 304. Further, the enable signal EN is also input to the timer circuit 304, and a clock pulse not shown is input. Also, the timer circuit 304 calculates the time from when the enable signal EN that makes the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 active and the enable signal EN that makes the detection of the detection voltage Cc of the piezoelectric element 60 active are input, until the output voltage Cp output by the comparison circuit 303 becomes the H level based on the clock pulse. Also, the timer circuit 304 outputs the calculation result as a detection signal Cap.

[0072] An example of the operation of the measurement circuit 300 configured in the above-described manner will be described. Figure 5 Fig. 2 is a diagram for describing an example of the operation of the measurement circuit 300. In addition, in Fig. 2, the logic level of the enable signal EN is set to the H level in a case where the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 is enabled, and the logic level of the enable signal EN is set to the L level in a case where the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 is not enabled. Figure 5

[0073] As shown in Fig. 2, at time t1, when the enable signal EN of the H level is input to the measurement circuit 300, one end and the other end of the switch 302 are controlled to the on state. Thus, the current Icnt output from the current source 301 is supplied to the piezoelectric element 60 via the switch 302. Therefore, the voltage value of the piezoelectric element 60 rises based on the capacity component of the piezoelectric element 60 and the current value of the current Icnt. That is, the detection voltage Cc indicating the voltage value of the piezoelectric element 60 gradually rises. Figure 4

[0074] Further, at time t1, the enable signal EN of the H level is also input to the timer circuit 304. The timer circuit 304 starts the measurement of time by being input the enable signal EN of the H level. Specifically, the timer circuit 304 starts the counting of the number of pulses of the unillustrated clock pulse input.

[0075] Thereafter, at time t2, the detection voltage Cc indicating the voltage value of the piezoelectric element 60 is higher than the reference voltage Vref, and thus the comparison circuit 303 outputs the output voltage Cp of the H level. The output voltage Cp of the H level output from the comparison circuit 303 is input to the timer circuit 304. The timer circuit 304 stops the measurement of time and the counting of the number of pulses of the clock pulse by being input the output voltage Cp of the H level. Further, the timer circuit 304 calculates the charging time Tch based on the counted number of pulses of the clock pulse. Thereafter, the timer circuit 304 generates and outputs the detection signal Cap including the calculated charging time Tch.

[0076] ​​At time t3 after the detection signal Cap is output from the timer circuit 304, the enable signal EN of L level is input to the measurement circuit 300. Thus, the supply of the current Icnt output from the current source 301 to the piezoelectric element 60 is stopped. Therefore, the voltage value of the piezoelectric element 60 gradually decreases. Also, the detection voltage Cc representing the voltage value of the piezoelectric element 60 becomes lower than the reference voltage Vref, and thus the comparison circuit 303 outputs the output voltage Cp of L level. Thus, the calculation of the electrostatic capacitance of the piezoelectric element 60 in the measurement circuit 300 ends.

[0077] That is, the measurement circuit 300 of the first embodiment measures the charging time Tch required for charging of the piezoelectric element 60 which changes in accordance with the electrostatic capacitance of the piezoelectric element 60 by taking the detection voltage Cc representing the voltage value of the piezoelectric element 60 in the case where the piezoelectric element 60 is supplied with the current Icnt, and outputs the measurement result as the detection signal Cap.

[0078] Here, the method of measuring the electrostatic capacitance by the measurement circuit 300 is not limited to the method using the Figure 5 and Figure 4 described above, and various techniques capable of measuring the electrostatic capacitance of the piezoelectric element 60 can be applied, but the measurement circuit 300 is preferably configured as described by Figure 5 and Figure 6 Thus, the measurement circuit 300 can be configured by a plurality of transistors, and as a result, the measurement circuit 300 can be implemented as one or a plurality of integrated circuits. Thus, the miniaturization of the measurement circuit 300 is possible.

[0079] Control method of liquid discharge system

[0080] Here, the control method of the liquid discharge system SY configured in the above-described manner is described. The liquid discharge system SY of the present embodiment includes the piezoelectric element 60 which is displaced based on the drive signal COM to cause ink to be discharged, and the drive signal output circuit 50 which outputs the drive signal COM, and in the control method of the liquid discharge system SY, includes a step of measuring the electrostatic capacitance of the piezoelectric element 60, and a step of judging the deterioration state of the piezoelectric element 60 based on the measured electrostatic capacitance.

[0081] Figure 6Fig. 1 is a diagram for illustrating an example of a liquid ejection system SY. As shown in Fig. 1, the liquid ejection system SY includes a liquid ejection device 1 and a control circuit 100. The liquid ejection device 1 is configured to perform ejection of liquid onto a medium. The control circuit 100 is configured to control the liquid ejection device 1. The liquid ejection system SY is configured to perform the control method of the present application. Figure 7 As shown in Fig. 1, in the liquid ejection system SY of the first embodiment, the control circuit 100 provided in the liquid ejection device 1 counts the number of times of ejection of ink onto the medium. Further, the control circuit 100 performs determination as to whether the number of times of ejection of ink onto the medium has reached a predetermined number (Step S110).

[0082] In a case where the control circuit 100 determines that the number of times of ejection of ink onto the medium has not reached the predetermined number (NO in Step S110), the control circuit 100 does not perform determination of the deterioration state of the piezoelectric element 60, but continues counting the number of times of ejection. On the other hand, in a case where the control circuit 100 determines that the number of times of ejection of ink onto the medium has reached the predetermined number (YES in Step S110), the control circuit 100 performs determination of the deterioration state of the piezoelectric element 60 and processing performed on the basis of the determination result of the deterioration state. That is, in the liquid ejection system SY of the first embodiment, the control circuit 100 determines, as a trigger, the number of times of ejection of ink onto the medium, and determines whether or not determination of the deterioration state of the piezoelectric element 60 and processing performed on the basis of the determination result of the deterioration state are required.

[0083] In addition, the trigger for the control circuit 100 to determine whether or not determination of the deterioration state of the piezoelectric element 60 and processing performed on the basis of the determination result of the deterioration state are required is not limited to the number of times of ejection of ink described above, but may be, for example, timing at which POR (Power On Reset) is performed by one or a plurality of semiconductor devices including the control circuit 100, by the liquid ejection device 1 being powered on in a case where the driving time of the liquid ejection device 1 reaches a predetermined time or in a case where the number of media on which the liquid ejection device 1 forms an image reaches a predetermined number.

[0084] In a case where the control circuit 100 determines that the number of times of ejection of ink onto the medium has reached the predetermined number (YES in Step S110), the control circuit 100 causes the measurement circuit 300 to acquire the electrostatic capacitance of the piezoelectric element 60 (Step S120). Specifically, the control circuit 100 outputs an enable signal EN that sets acquisition of the electrostatic capacitance of the piezoelectric element 60 to be valid, to the measurement circuit 300. Thus, the measurement circuit 300 acquires the electrostatic capacitance of the piezoelectric element 60 or a physical quantity corresponding to the electrostatic capacitance of the piezoelectric element 60.

[0085] Thereafter, the deterioration state of the piezoelectric element 60 is judged by the judging circuit 310 on the basis of the electrostatic capacity of the piezoelectric element 60 acquired by the measuring circuit 300 or the physical quantity corresponding to the electrostatic capacity of the piezoelectric element 60 (step S130). That is, the deterioration state of the piezoelectric element 60 is judged by the judging circuit 310 on the basis of the electrostatic capacity of the piezoelectric element 60 measured by the measuring circuit 300. Moreover, on the basis of the judgment result of the judging circuit 310, the life span of the piezoelectric element 60 is estimated by the life span estimation circuit 320 (step S140), and the correction value of the drive signal COM is calculated by the correction value calculating circuit 330 (step S150), and the control circuit 100 performs the correction of the drive signal COM on the basis of the correction value of the drive signal COM calculated.

[0086] In the control method of the liquid ejecting system SY described above, by including the process of measuring the electrostatic capacity of the piezoelectric element 60 by the measuring circuit 300 and the process of judging the deterioration state of the piezoelectric element 60 on the basis of the electrostatic capacity measured by the judging circuit 310, it is possible to detect and judge the deterioration state of the piezoelectric element 60 which can be different depending on the history of the driving conditions with high precision, and by improving the detection precision and the judgment precision of the deterioration state of the piezoelectric element 60, it is possible to perform appropriate correction of the driving conditions of the piezoelectric element 60, and furthermore, it is possible to improve the calculation precision of the estimated life span of the piezoelectric element 60.

[0087] Here, the drive signal COM is one example of the drive signal, and in view of the fact that the drive signal VOUT is a signal generated by making the trapezoidal waveform Adp included in the drive signal COM selected or non-selected, the drive signal VOUT is also one example of the drive signal. Further, the electrostatic capacity of the piezoelectric element 60 is one example of the first electrostatic capacity, and the electrostatic capacity of the dummy piezoelectric element 60d is one example of the second electrostatic capacity. Moreover, the correction value calculating circuit 330 which calculates the correction value of the drive signal COM on the basis of the deterioration state of the piezoelectric element 60, and the control circuit 100 which corrects the voltage value of the drive signal COM on the basis of the correction value calculated by the correction value calculating circuit 330 are one example of the drive voltage correction circuit which corrects the voltage value of the drive signal COM on the basis of the electrostatic capacity of the piezoelectric element 60.

[0088] Effects

[0089] As described above, the liquid ejection system SY of the first embodiment measures the electrostatic capacitance of the piezoelectric element 60 by the measurement circuit 300 and judges the deterioration state of the piezoelectric element 60 by the judgment circuit 310 based on the electrostatic capacitance of the piezoelectric element 60 measured by the measurement circuit 300. This enables the detection of the deterioration of the piezoelectric element 60 without depending on the driving conditions of the piezoelectric element 60.

[0090] Furthermore, the liquid ejection system SY of this embodiment includes a correction value calculation circuit 330, which corrects the voltage value of the drive signal COM based on the deterioration state of the piezoelectric element 60 determined by the judgment circuit 310. Therefore, even if the displacement of the piezoelectric element 60 deteriorates, the possibility of fluctuations in the ejected liquid volume can be reduced, thereby improving the ink ejection accuracy in the liquid ejection system SY.

[0091] Furthermore, the liquid ejection system SY of this embodiment includes: a lifespan estimation circuit 320, which estimates the lifespan of the piezoelectric element 60 based on the degradation state of the piezoelectric element 60 determined by the judgment circuit 310; and a notification unit 110, which notifies the user of the lifespan information of the piezoelectric element 60 estimated by the lifespan estimation circuit 320. Therefore, the user can be notified of the lifespan of the piezoelectric element 60 and the liquid ejection system SY at appropriate intervals, thereby improving user convenience.

[0092] 2. Second Implementation Method

[0093] Next, the liquid ejection system SY according to the second embodiment will be described. When describing the liquid ejection system SY according to the second embodiment, the same symbols will be used for structures identical to those in the liquid ejection system SY according to the first embodiment, and detailed descriptions will be simplified or omitted.

[0094] Figure 7 This diagram illustrates the structure of the liquid ejection system SY according to the second embodiment. Figure 8 As shown, the liquid ejection system SY of the second embodiment includes a dummy piezoelectric element 60d. The dummy piezoelectric element 60d differs from the piezoelectric element 60 in that it is not a structure included in the ejection section 600. That is, the dummy piezoelectric element 60d does not have a corresponding vibrating plate 621, cavity 631, and nozzle 651. Therefore, the dummy piezoelectric element 60d is displaced based on the drive signal VOUT obtained from the drive signal COM, but does not eject ink.

[0095] In the liquid ejecting system SY of the second embodiment, the measurement circuit 300 measures the electrostatic capacitance of the piezoelectric element 60 that ejects ink, and the electrostatic capacitance of the dummy piezoelectric element 60d that does not eject ink. Specifically, the measurement circuit 300 acquires the voltage value of at least one electrode 611 of the n piezoelectric elements 60 as a detection voltage Cc by being inputted with the enable signal EN that sets the detection of the voltage value to be valid from the control circuit 100. Also, the measurement circuit 300 generates a detection signal Cap corresponding to the electrostatic capacitance of the piezoelectric element 60 based on the acquired detection voltage Cc, and outputs it to the determination circuit 310. Furthermore, the measurement circuit 300 acquires the voltage value of the electrode of one of the dummy piezoelectric elements 60d as a detection voltage Cd by being inputted with the enable signal ENd that sets the detection of the voltage value to be valid from the control circuit 100. Also, the measurement circuit 300 generates a detection signal Capd corresponding to the electrostatic capacitance of the dummy piezoelectric element 60d based on the acquired detection voltage Cd, and outputs it to the determination circuit 310.

[0096] In the liquid ejecting system SY of the second embodiment, the measurement circuit 300 determines the deterioration state of the piezoelectric element 60 based on the electrostatic capacitance of the piezoelectric element 60 and the electrostatic capacitance of the dummy piezoelectric element 60d. Specifically, the determination circuit 310 compares the detection signal Cap corresponding to the electrostatic capacitance of the piezoelectric element 60 and the detection signal Capd corresponding to the electrostatic capacitance of the dummy piezoelectric element 60d, and determines the deterioration state of the piezoelectric element 60 based on the comparison result. Here, since the dummy piezoelectric element 60d is not included in the structure of the ejecting portion 600 that ejects ink, the pressure accompanying the ejection of ink does not affect the dummy piezoelectric element 60d. By using the detection signal Capd that represents the electrostatic capacitance of the dummy piezoelectric element 60d as a reference value to discriminate the deterioration state of the piezoelectric element 60, it is possible to discriminate the deterioration state of the piezoelectric element 60 based on the same reference, and as a result, it is possible to improve the determination accuracy of the deterioration state in the determination circuit 310.

[0097] Here, it is preferable that the dummy piezoelectric element 60d is manufactured by the same manufacturing process as the piezoelectric element 60. By doing so, it is possible to reduce the possibility that the measurement of the deterioration state of the piezoelectric element 60 is different due to manufacturing variations, and it is possible to further improve the determination accuracy of the deterioration state in the determination circuit 310.

[0098] Here, one example of the specific structure of the measurement circuit 300 of the second embodiment will be described. Figure 8 FIG. 1 is a diagram showing one example of the structure of the measurement circuit 300 of the second embodiment. As shown in FIG. 1, the measurement circuit 300 of the second embodiment includes a measurement circuit 300a that measures the electrostatic capacitance of the piezoelectric element 60, and a measurement circuit 300b that measures the electrostatic capacitance of the dummy piezoelectric element 60d. Figure 9As shown, the measurement circuit 300 has a current source 301, switches 302-1, 302-2, 302d-1, 302d-2, a comparison circuit 303, and a timer circuit 304.

[0099] In the current source 301, a voltage Vdd1 is supplied. Also, the current source 301 generates and outputs a current Icnt of which a current value is constant based on the voltage Vdd1. As such a current source 301, for example, either a combination of one or more transistors or a constant current Zener diode or the like can be used.

[0100] One end of the switch 302-1 is electrically connected to the output of the current source 301, and the other end is electrically connected to the electrode 611 of the piezoelectric element 60. Also, one end of the switch 302-2 is electrically connected to the electrode 611 of the piezoelectric element 60, and the other end is electrically connected to one input terminal of the comparison circuit 303. Also, the on / off state of each of the one end and the other end of the switches 302-1, 302-2 is switched based on an enable signal EN input to the control terminal.

[0101] Specifically, in a case where the enable signal EN that makes the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 active is input to each of the control terminals of the switches 302-1, 302-2, each of the one end and the other end of the switches 302-1, 302-2 is controlled to be in the on state, and in a case where the enable signal EN that does not make the detection of the electrostatic capacity of the piezoelectric element 60 in the measurement circuit 300 active is input to each of the control terminals of the switches 302-1, 302-2, each of the one end and the other end of the switches 302-1, 302-2 is controlled to be in the off state.

[0102] One end of the switch 302d-1 is electrically connected to the output of the current source 301, and the other end is electrically connected to one electrode of the dummy piezoelectric element 60d. Also, one end of the switch 302d-2 is electrically connected to one electrode of the dummy piezoelectric element 60d, and the other end is electrically connected to one input terminal of the comparison circuit 303. Also, the on / off state of each of the one end and the other end of the switches 302d-1, 302d-2 is switched based on an enable signal End input to the control terminal.

[0103] Specifically, in a case where the enable signal End that makes the detection of the electrostatic capacitance of the dummy piezoelectric element 60d in the measurement circuit 300 active is input to the control terminal of each of the switches 302d-1 and 302d-2, one end and the other end of each of the switches 302d-1 and 302d-2 are controlled to be in an on state, and in a case where the enable signal End that does not make the detection of the electrostatic capacitance of the dummy piezoelectric element 60d in the measurement circuit 300 active is input to the control terminal of each of the switches 302d-1 and 302d-2, one end and the other end of each of the switches 302d-1 and 302d-2 are controlled to be in an off state.

[0104] Here, the enable signal EN input to the control terminal of each of the switches 302-1 and 302-2 and the enable signal End input to the control terminal of each of the switches 302d-1 and 302d-2 do not become a logic level that makes the detection of the electrostatic capacitance active at the same time.

[0105] In the power supply terminal on the high potential side of the comparison circuit 303, a voltage Vdd2 is supplied, and in the power supply terminal on the low potential side of the comparison circuit 303, a voltage Vss is input. Further, one input terminal of the comparison circuit 303 is electrically connected to the other end of the switch 302-2 and the other end of the switch 302d-2, and a reference voltage Vref is input to the other input terminal of the comparison circuit 303. Moreover, the comparison circuit 303 outputs an H-level output voltage Cp by a signal input to one input terminal being higher than the reference voltage Vref, and outputs an L-level output voltage Cp in a case where the signal input to one input terminal is equal to or lower than the reference voltage Vref.

[0106] That is, in a case where the enable signal EN that makes the detection of the electrostatic capacitance of the piezoelectric element 60 active is input to the measurement circuit 300, the comparison circuit 303 compares the detection voltage Cc and the reference voltage Vref and outputs an output voltage Cp based on the comparison result, and in a case where the enable signal End that makes the detection of the electrostatic capacitance of the dummy piezoelectric element 60d active is input to the measurement circuit 300, the comparison circuit 303 compares the detection voltage Cd and the reference voltage Vref and outputs an output voltage Cp based on the comparison result.

[0107] The output voltage Cp output by the comparator circuit 303 is input to the timer circuit 304. Furthermore, enable signals EN and ENd are also input to the timer circuit 304, along with a clock pulse (not shown). The timer circuit 304 measures the time from when the enable signal EN, which activates the detection of the electrostatic capacitance of the piezoelectric element 60, is input to the measurement circuit 300, until the output voltage Cp output by the comparator circuit 303 reaches level H, and outputs the measurement result as a detection signal Cap. Additionally, the timer circuit 304 measures the time from when the enable signal ENd, which activates the detection of the electrostatic capacitance of the dummy piezoelectric element 60d, is input to the measurement circuit 300, until the output voltage Cp output by the comparator circuit 303 reaches level H, and outputs the measurement result as a detection signal Capd to the judgment circuit 310.

[0108] The judgment circuit 310 judges the deterioration state of the piezoelectric element 60 by comparing the detection signal Cap and the detection signal Capd.

[0109] In the liquid ejection system SY of the second embodiment constructed as described above, in addition to the same effects as in the first embodiment, the degradation state of the piezoelectric element 60 is identified by using the detection signal Capd, which represents the electrostatic capacitance of the dummy piezoelectric element 60d, as a reference value. Therefore, the degradation state of the piezoelectric element 60 can be identified based on the same reference. Thus, the accuracy of determining the degradation state of the piezoelectric element 60 in the determination circuit 310 can be further improved.

[0110] 3. Third Implementation Method

[0111] Next, the liquid ejection system SY according to the third embodiment will be described. When describing the liquid ejection system SY according to the third embodiment, the same symbols will be used for structures identical to those in the first and second embodiments, and detailed descriptions will be simplified or omitted.

[0112] Figure 9 This diagram illustrates the structure of the liquid ejection system SY according to the third embodiment. ​ As shown, the liquid ejection system SY of the third embodiment includes: a liquid ejection device 1, which includes a piezoelectric element 60 that is displaced based on a drive signal COM to eject ink; and a server 70, which is provided in a manner that enables communication with the liquid ejection device 1.

[0113] The liquid ejecting apparatus 1 of the third embodiment has a transmission module 350 and a reception module 360 in place of the determination circuit 310, the life estimation circuit 320, and the correction value calculation circuit 330. Further, the server 70 has a reception module 700, a transmission module 750, a determination circuit 710, a life estimation circuit 720, and a correction value calculation circuit 730. Here, the determination circuit 710 possessed by the server 70 corresponds to the determination circuit 310 of the first and second embodiments, the life estimation circuit 720 possessed by the server 70 corresponds to the life estimation circuit 320 of the first and second embodiments, and the correction value calculation circuit 730 possessed by the server 70 corresponds to the correction value calculation circuit 330 of the first and second embodiments.

[0114] In the transmission module 350, the detection signal Cap output from the measurement circuit 300 is input. The transmission module 350 transmits the input detection signal Cap as a communication signal St toward the reception module 700 possessed by the server 70. The reception module 700 receives the communication signal St transmitted by the transmission module 350. Further, the reception module 700 acquires the detection signal Cap from the received communication signal St and outputs the acquired detection signal Cap as a detection signal rCap to the determination circuit 710. That is, the transmission module 350 and the reception module 700 are provided in a manner capable of communicating. Such transmission module 350 and reception module 700 are connected by communication, for example, via the Internet.

[0115] The determination circuit 710, like the determination circuit 310 of the first embodiment, determines the deterioration state of the piezoelectric element 60 possessed by the liquid ejecting apparatus 1 on the basis of the detection signal rCap and outputs a state signal rCst indicating the determination result to the life estimation circuit 720 and the correction value calculation circuit 730.

[0116] The life estimation circuit 720, like the life estimation circuit 320 of the first embodiment, estimates the life of the piezoelectric element 60 possessed by the liquid ejecting apparatus 1 on the basis of the input state signal rCst. Further, the life estimation circuit 720 outputs a life notification signal rEl including information on the estimated life of the piezoelectric element 60 to the transmission module 750.

[0117] The correction value calculation circuit 730, like the correction value calculation circuit 330 of the first embodiment, judges whether or not to correct the voltage value of the drive signal COM that drives the piezoelectric element 60 possessed by the liquid ejecting device 1, based on the state signal rCst that is input. Also, the correction value calculation circuit 730, in a case where it is judged that correction of the voltage value of the drive signal COM is necessary, calculates a correction value that corrects the voltage value of the drive signal COM, and outputs a correction signal Cv that includes information of the calculated correction value to the transmission module 750.

[0118] The transmission module 750 transmits, as a communication signal Sr, a signal that includes at least one of the life notification signal rEl input from the life estimation circuit 720 and the correction signal rCv input from the correction value calculation circuit 730, toward the reception module 360 possessed by the liquid ejecting device 1. The reception module 360 receives the communication signal Sr transmitted by the transmission module 750. Also, the reception module 360 generates a state signal Hdi that includes at least one of the life notification signal rEl and the correction signal Cv, based on the received communication signal Sr, and outputs it to the control circuit 100. That is, the transmission module 750 and the reception module 360 are provided in a manner that enables communication. Such transmission module 750 and reception module 360 are connected, for example, via the Internet and by communication.

[0119] The control circuit 100, in a case where the life notification signal rEl is included in the input state signal Hdi, and in a case where the life notification signal rEl included in the input state signal Hdi includes information indicating that the piezoelectric element 60 will soon reach the life or has reached the life, generates a notification signal Inf that notifies a message indicating that the piezoelectric element 60 will soon reach the life or has reached the life to the user, and outputs it to the notification section 110.

[0120] Further, the control circuit 100, in a case where the correction signal Cv is included in the input state signal Hdi, corrects the base drive signal dA based on the input correction signal Cv, and outputs it to the drive signal output circuit 50.

[0121] As described above, the liquid discharge system SY of the third embodiment includes the liquid discharge apparatus 1 including the piezoelectric element 60 that displaces based on the drive signal VOUT obtained from the drive signal COM to cause ink to be discharged, the server 70 provided in a manner capable of communicating with the liquid discharge apparatus 1, the drive signal output circuit 50 that outputs the drive signal COM, and the measurement circuit 300 that measures the electrostatic capacitance of the piezoelectric element 60, the server 70 having the reception module 700 that receives the communication signal St including information on the electrostatic capacitance of the piezoelectric element 60, the determination circuit 710, and the transmission module 750 that transmits the communication signal Sr including at least one of the life notification signal rEl and the correction signal rCv corresponding to the state signal rCst that is the result of determination by the determination circuit 710.

[0122] That is, the server 70 included in the liquid discharge system SY of the third embodiment is provided in a manner capable of communicating with the liquid discharge apparatus 1 including the piezoelectric element 60 that displaces based on the drive signal VOUT obtained from the drive signal COM to cause ink to be discharged, the server 70 having the reception module 700 that receives the communication signal St including the electrostatic capacitance of the piezoelectric element 60 measured by the measurement circuit 300, the determination circuit 710 that determines the deterioration state of the piezoelectric element 60 based on the communication signal St, and the transmission module 750 that transmits the communication signal Sr including at least one of the life notification signal rEl and the correction signal rCv corresponding to the state signal rCst that is the result of determination by the determination circuit 710.

[0123] The liquid discharge system SY and the server 70 configured in the above-described manner can also exhibit the same effects as the liquid discharge system SY of the first embodiment.

[0124] Here, the communication signal St including information on the electrostatic capacitance of the piezoelectric element 60 included in the liquid discharge apparatus 1 is one example of electrostatic capacitance information, the reception module 700 that receives the communication signal St is one example of a reception section, the determination circuit 710 included in the server 70 is one example of a determination circuit in the third embodiment, the communication signal Sr based on the state signal rCst indicating the result of determination by the determination circuit 710 on the deterioration state of the piezoelectric element 60 is one example of determination result information, and the transmission module 750 that transmits the communication signal Sr is one example of a transmission section.

[0125] While the embodiments and modifications have been described above, the present application is not limited to these embodiments, but can be implemented in various forms without departing from the gist thereof. For example, the above-described embodiments can be appropriately combined.

[0126] The present application includes structures (for example, structures having the same function, method, and result, or structures having the same purpose and effect) substantially the same as the structures described in the embodiments. In addition, the present application includes structures in which non-essential parts of the structures described in the embodiments are replaced. Furthermore, the present application includes structures capable of achieving the same effects as the structures described in the embodiments, or structures capable of achieving the same purpose. In addition, the present application includes structures in which publicly known technologies are added to the structures described in the embodiments.

[0127] The following can be derived from the above-described embodiments.

[0128] One embodiment of a liquid discharge system includes:

[0129] a piezoelectric element that is displaced based on a drive signal to discharge a liquid;

[0130] a drive signal output circuit that outputs the drive signal;

[0131] a measurement circuit that measures a first electrostatic capacitance of the piezoelectric element;

[0132] a determination circuit that determines a deterioration state of the piezoelectric element based on the first electrostatic capacitance.

[0133] According to the liquid discharge system, the deterioration state of the piezoelectric element is determined based on the electrostatic capacitance of the piezoelectric element, so that the displacement amount of the piezoelectric element can be accurately obtained without depending on the driving history of the piezoelectric element.

[0134] In one embodiment of the liquid discharge system, the following can be adopted, that is,

[0135] a drive voltage correction circuit that corrects a voltage value of the drive signal based on the deterioration state.

[0136] According to the liquid discharge system, the drive signal can be most appropriately corrected in accordance with the displacement amount of the piezoelectric element.

[0137] In one embodiment of the liquid discharge system, the following can be adopted, that is,

[0138] a life span estimation circuit that estimates a life span of the piezoelectric element based on the deterioration state;

[0139] a notification unit that notifies information on the life span estimated by the life span estimation circuit.

[0140] According to the liquid discharge system, it is possible to notify the user of the life span of at least one of the piezoelectric element and the liquid discharge system based on the displacement amount of the piezoelectric element.

[0141] In one embodiment of the liquid discharge system, the following configuration can be employed, that is,

[0142] The measurement circuit has:

[0143] a current source that outputs a constant current;

[0144] a switch that switches electrical connection between the current source and the piezoelectric element;

[0145] a comparison circuit that is electrically connected to the piezoelectric element.

[0146] According to the liquid discharge system, it is possible to measure the electrostatic capacitance of the piezoelectric element with high precision based on the resolution of the clock signal.

[0147] In one embodiment of the liquid discharge system, the following configuration can be employed, that is,

[0148] a dummy piezoelectric element that is displaced based on the drive signal but does not cause liquid to be discharged,

[0149] the measurement circuit measures a second electrostatic capacitance of the dummy piezoelectric element,

[0150] the judgment circuit judges the deterioration state of the piezoelectric element based on the first electrostatic capacitance and the second electrostatic capacitance.

[0151] According to the liquid discharge system, it is possible to judge the state of deterioration of the piezoelectric element taking into account parameters such as temperature and humidity.

[0152] In one embodiment of the liquid discharge system, the following configuration can be employed, that is,

[0153] a liquid discharge apparatus that includes the piezoelectric element;

[0154] a server that is provided in a manner capable of communicating with the liquid discharge apparatus,

[0155] the server has:

[0156] a reception unit that receives electrostatic capacitance information including the first electrostatic capacitance;

[0157] the judgment circuit;

[0158] a transmission unit that transmits judgment result information including a result of judgment by the judgment circuit.

[0159] One embodiment of a server is provided in a manner capable of communicating with a liquid discharge device including a piezoelectric element that is displaced based on a drive signal to discharge a liquid, and the server includes:

[0160] a reception unit that receives electrostatic capacitance information including an electrostatic capacitance of the piezoelectric element measured by a measurement circuit;

[0161] a judgment circuit that judges a deterioration state of the piezoelectric element based on the electrostatic capacitance information;

[0162] a transmission unit that transmits judgment result information including a result of judgment by the judgment circuit.

[0163] According to the server, the deterioration state of the piezoelectric element is judged based on the electrostatic capacitance of the piezoelectric element, so that the displacement amount of the piezoelectric element can be accurately obtained without depending on the driving history of the piezoelectric element.

[0164] One embodiment of a control method of a liquid discharge system is,

[0165] the liquid discharge system includes:

[0166] a piezoelectric element that is displaced based on a drive signal to discharge a liquid;

[0167] a drive signal output circuit that outputs the drive signal,

[0168] In the control method of the liquid discharge system, there are:

[0169] a step of measuring an electrostatic capacitance of the piezoelectric element;

[0170] a step of judging a deterioration state of the piezoelectric element based on the electrostatic capacitance.

[0171] According to the liquid discharge system, the deterioration state of the piezoelectric element is judged based on the electrostatic capacitance of the piezoelectric element, so that the displacement amount of the piezoelectric element can be accurately obtained without depending on the driving history of the piezoelectric element.

[0172] Explanation of symbols

[0173] 1…liquid ejecting apparatus; 50…drive signal output circuit; 60…piezoelectric element; 60d…dummy piezoelectric element; 70…server; 100…control circuit; 110…notification section; 210…drive signal selection control circuit; 230…selection circuit; 300…measurement circuit; 301…current source; 302…switch; 303…comparison circuit; 304…timer circuit; 310…determination circuit; 320…life span estimation circuit; 330…correction value calculation circuit; 350…transmission module; 360…reception module; 600…ejection section; 601…piezoelectric body; 611, 612…electrode; 621…vibration plate; 631…cavity; 632…nozzle plate; 641…liquid reservoir; 651…nozzle; 661…supply port; 700…reception module; 710…determination circuit; 720…life span estimation circuit; 730…correction value calculation circuit; 750…transmission module; SY…liquid ejecting system.

Claims

1. A liquid ejection system, characterized by, Possessing: a piezoelectric element that is displaced based on a drive signal to cause liquid to be ejected; a drive signal output circuit that outputs the drive signal; a measurement circuit that measures a first electrostatic capacitance of the piezoelectric element; a determination circuit that determines a deterioration state of the piezoelectric element based on the first electrostatic capacitance; a life span inference circuit that infers a life span of the piezoelectric element based on the deterioration state and generates a life span notification signal that contains information indicating a meaning that the piezoelectric element will soon reach the life span or a meaning that the piezoelectric element has reached the life span; a control circuit that generates a notification signal for notifying a user of a meaning that the piezoelectric element will soon reach the life span or a meaning that the piezoelectric element has reached the life span based on the life span notification signal input from the life span inference circuit; a notification section that notifies of life span information of the piezoelectric element based on the notification signal input from the control circuit.

2. The liquid ejection system according to claim 1, characterized by: possessing a drive voltage correction circuit that corrects a voltage value of the drive signal based on the deterioration state.

3. The liquid ejection system according to claim 1, characterized in that: the measurement circuit has: a current source that outputs a constant current; a switch that switches an electrical connection between the current source and the piezoelectric element; a comparison circuit that is electrically connected to the piezoelectric element.

4. The liquid ejection system according to claim 1, characterized by: possessing a dummy piezoelectric element that is displaced based on the drive signal but does not cause liquid to be ejected, the measurement circuit measures a second electrostatic capacitance of the dummy piezoelectric element, the determination circuit determines the deterioration state of the piezoelectric element based on the first electrostatic capacitance and the second electrostatic capacitance.

5. The liquid ejection system of claim 1, wherein, Possessing: a liquid ejection device that includes the piezoelectric element; a server that is provided in a manner capable of communicating with the liquid ejection device, the server has: a reception section that receives electrostatic capacitance information containing the first electrostatic capacitance; the determination circuit; a transmission section that transmits determination result information containing a determination result of the determination circuit.

6. A server, characterized by is provided in a manner capable of communicating with a liquid ejection device that includes a piezoelectric element that is displaced based on a drive signal to cause liquid to be ejected, the server possesses: a reception section that receives electrostatic capacitance information containing an electrostatic capacitance of the piezoelectric element measured by a measurement circuit; a determination circuit that determines a deterioration state of the piezoelectric element based on the electrostatic capacitance information; a life span inference circuit that infers a life span of the piezoelectric element based on the deterioration state and generates a life span notification signal that contains information indicating a meaning that the piezoelectric element will soon reach the life span or a meaning that the piezoelectric element has reached the life span; a transmission section that transmits the life span notification signal.

7. A control method of a liquid discharge system, characterized by the liquid discharge system having: a piezoelectric element that is displaced based on a drive signal to cause a liquid to be discharged; a drive signal output circuit that outputs the drive signal, in the control method of the liquid discharge system, there are: a process of measuring an electrostatic capacity of the piezoelectric element; a process of judging a deterioration state of the piezoelectric element based on the electrostatic capacity; a process of inferring a lifetime of the piezoelectric element based on the deterioration state, and generating a lifetime notification signal that contains information indicating a meaning that the piezoelectric element will reach the lifetime soon, or a meaning that the piezoelectric element has reached the lifetime; a process of generating a notification signal for notifying a user of the meaning that the piezoelectric element will reach the lifetime soon, or the meaning that the piezoelectric element has reached the lifetime, based on the lifetime notification signal that is input; a process of notifying the lifetime information of the piezoelectric element based on the notification signal that is input.

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