JP4145936B2 - Liquid consumption state detection method and ink jet recording apparatus - Google Patents

Description

  The present invention relates to an ink jet recording apparatus that can use a liquid container having a piezoelectric device that detects a consumption state of an internal liquid, and a method for detecting a liquid consumption state of the liquid container.

  An ink jet recording apparatus mounts an ink jet recording head including pressure generating means for pressurizing a pressure generating chamber and a nozzle opening for ejecting pressurized ink as ink droplets from the nozzle opening on a carriage. The ink jet recording apparatus is configured to be able to continue printing while supplying ink from an ink cartridge to a recording head via a flow path. The ink cartridge is configured as a removable ink cartridge so that the user can easily replace it when the ink is consumed.

  Conventionally, as a method for managing ink consumption of an ink cartridge, the number of ink droplets discharged from a recording head and the amount of ink sucked by maintenance are integrated by software, and the ink consumption is managed by calculation. There is a method of managing a point in time when a predetermined amount of ink is actually consumed by attaching a surface detection electrode.

  The method of managing the ink consumption by calculating the number of ink droplets discharged and the amount of ink by software causes an error depending on the printing form on the user side, or a large error when re-installing the same ink cartridge . In addition, an error that cannot be ignored occurs between the calculated ink consumption and the actual consumption depending on the use environment.

  The method for managing the time point when the ink is consumed by the electrode can actually detect the liquid level of the ink, so that the presence or absence of ink can be managed with high reliability. However, since the detection of the ink level depends on the conductivity of the ink, the types of ink that can be detected are limited, and the electrode seal structure is complicated. Further, since a noble metal having high conductivity and high corrosion resistance is usually used as the electrode material, the manufacturing cost of the ink cartridge is increased. Furthermore, since it is necessary to mount two electrodes, the number of manufacturing steps increases, resulting in an increase in manufacturing cost.

  Therefore, there is a method of detecting the ink level by detecting a change in acoustic impedance by a piezoelectric device using a piezoelectric material. In the method of detecting the ink level using a piezoelectric device, the presence or absence of ink can be managed with high reliability, the electrode sealing structure is not complicated, and the manufacturing cost of the ink cartridge is low.

  However, if there is a defect in the piezoelectric device, the piezoelectric device does not operate normally and erroneously determines the presence or absence of ink in the ink cartridge. Therefore, it is advantageous if it can be determined whether the piezoelectric device operates normally.

  In addition, in the ink cartridge with defects, the amount of ink decreases due to ink leakage or ink evaporation. Accordingly, it is desired that the piezoelectric device can detect that a predetermined amount of ink is not contained due to a defect of the ink cartridge or the like.

  In addition, it is advantageous if it can be confirmed that a predetermined amount of ink is contained in the ink cartridge even when the ink cartridge is manufactured.

  Further, when the ink cartridge is reused for recycling or the like, the ink is refilled in the ink cartridge. It is advantageous if it is possible to detect whether a predetermined amount of ink has actually entered the ink cartridge after ink filling.

  Furthermore, it is advantageous if the ink cartridge is not correctly mounted or the ink jet recording apparatus is tilted by checking the tilt of the liquid surface. Thereby, it is possible to prevent printing defects of the ink jet recording apparatus.

  SUMMARY An advantage of some aspects of the invention is that it provides a method and an apparatus for controlling an ink jet recording apparatus in accordance with a determination result of whether or not a liquid detection function of a piezoelectric device is defective.

  It is another object of the present invention to provide a liquid container capable of confirming that a predetermined amount of liquid is contained in the liquid container at the time of manufacturing or after manufacturing the liquid container.

  Furthermore, a liquid container capable of detecting when a predetermined amount of ink does not actually enter the liquid container due to a defect in the liquid container or the piezoelectric device, and an ink jet recording apparatus based on the detection result of the ink amount It is an object of the present invention to provide a method and apparatus for controlling the above.

  It is another object of the present invention to provide a liquid container capable of detecting the inclination of the liquid container when the liquid container is not correctly mounted, a method and apparatus for controlling the ink jet recording apparatus based on the detection result of the ink amount. And

  It is another object of the present invention to provide a liquid container and an ink jet recording apparatus that can easily and accurately detect the amount of ink in the container.

The present invention includes a container main body that contains a liquid to be supplied to a recording head that discharges ink droplets from a nozzle opening, and a piezoelectric device that detects the liquid in the container main body, and a liquid container mounted on an ink jet recording apparatus. In the method for detecting a liquid consumption state, a detection unit provided inside or outside the ink jet recording apparatus detects a vibration characteristic value of two piezoelectric devices provided in the liquid container, and the ink jet determining section provided inside or outside of the recording apparatus, whether or not the relationship between two of said piezoelectric device mutual oscillation characteristic values between the two oscillation characteristic value by comparing the meets predetermined relative condition have a, a determining step of determining the consumption condition of a liquid in the liquid container on the basis of said predetermined relative condition the vibration characteristic values of two of said piezoelectric device and the like A Ikoto, two of the piezoelectric device, respectively, and slightly below the liquid level in the liquid container of unused, are arranged in the vicinity of a bottom surface of the container body, it is characterized.

The present invention relates to an ink jet recording apparatus in which a liquid container having a container main body for containing a liquid and a piezoelectric device for detecting the liquid in the container main body is detachable, and receives ink from the liquid container and receives ink from a nozzle opening. A recording head that ejects droplets, and a control device that controls an operating state of the ink jet recording device, wherein the control device detects vibration characteristic values of the two piezoelectric devices provided in the liquid container. and parts, consumption of liquid in said liquid container based on whether the relationship between two of said piezoelectric device mutual oscillation characteristic values between the two oscillation characteristic value by comparing the meets predetermined relative condition possess a determining unit status, a predetermined relative condition is that the vibration characteristic values of the two said piezoelectric devices are equal, two of the piezoelectric device, respectively, Not It is characterized by being disposed slightly below the liquid level in the liquid container in use and near the bottom surface of the container main body .

  A reference example of the present invention is an ink jet recording apparatus in which a liquid container having a container main body that stores liquid supplied to a recording head that discharges ink droplets from nozzle openings and a piezoelectric device that detects the liquid in the container main body can be attached and detached. In the control method, a detection step in which the detection unit provided inside or outside the ink jet recording apparatus detects a characteristic value of the piezoelectric device, and a determination unit provided inside or outside the ink jet recording apparatus includes the characteristic. A determination step for determining whether or not a value satisfies a predetermined condition; and a control step for setting the ink jet recording apparatus in an operable state or an inoperable state based on a result of the determination step. To do.

  Preferably, the detection step is executed when the liquid container is mounted on the ink jet recording apparatus.

  Preferably, the measuring unit provided inside or outside the ink jet recording apparatus further includes a measuring step of measuring the amount of liquid consumption in the previous liquid storage container to at least a predetermined amount.

  Preferably, when the ink jet recording apparatus is in an inoperable state, the step of selecting to maintain the inoperable state of the ink jet recording apparatus or to switch the ink jet recording apparatus to an operable state. It has further.

  Preferably, the characteristic value is an element characteristic value of a piezoelectric element of the piezoelectric device.

  Preferably, the characteristic value is a vibration characteristic value of a vibration part of the piezoelectric device.

  Preferably, the liquid container is provided with at least two of the piezoelectric devices, and in the detection step, the detection unit detects vibration characteristic values of at least two of the piezoelectric devices, and in the determination step. The determination unit determines the consumption state of the liquid in the liquid container based on the relative condition of the vibration characteristic values of the at least two piezoelectric devices.

  A reference example of the present invention is an ink jet recording apparatus in which a liquid container having a container main body that stores liquid supplied to a recording head that discharges ink droplets from nozzle openings and a piezoelectric device that detects the liquid in the container main body can be attached and detached. In the control device, provided inside or outside the ink jet recording apparatus, a detection unit for detecting a characteristic value of the piezoelectric device, and provided inside or outside the ink jet recording apparatus, the characteristic value satisfies a predetermined condition. A determination unit that determines whether or not the condition is satisfied; and a control unit that sets the inkjet recording apparatus in an operable state or an inoperable state based on a determination result in the determination unit.

  Preferably, the detection unit detects vibration characteristic values of at least two of the piezoelectric devices provided in the liquid container, and the determination unit detects relative vibration characteristic values of the at least two piezoelectric devices. The consumption state of the liquid in the liquid container is determined based on the general conditions.

  A liquid container according to a reference example of the present invention includes a container main body that stores liquid, a liquid supply port that supplies the liquid to the outside of the container main body, and a piezoelectric device that detects the liquid in the container main body, The piezoelectric device is disposed near the liquid surface of the liquid in the container body when the liquid is not consumed.

  In addition, it preferably further includes an additional piezoelectric device for detecting the liquid in the container body.

  Preferably, the additional piezoelectric device is disposed in the vicinity of the bottom surface of the container body.

  Preferably, the additional piezoelectric device is disposed in the vicinity of the piezoelectric device, and an initial liquid level when the liquid in the container body is not consumed is the piezoelectric device and the additional piezoelectric device. Located between.

  Preferably, each of the piezoelectric device and the additional piezoelectric device has a vibration unit that contacts a medium in the container body, and a vibration characteristic value of the vibration unit is detected.

  Preferably, the liquid container is mounted on an ink jet recording apparatus that performs recording by a recording head that ejects ink droplets, and supplies the liquid in the container body to the recording head.

  A reference example of the present invention relates to an ink jet recording apparatus in which a liquid container having a container main body for containing a liquid and a piezoelectric device for detecting the liquid in the container main body is detachable. A recording head that discharges ink droplets from an opening; and a control device that controls an operating state of the ink jet recording apparatus. The control apparatus is provided inside or outside the ink jet recording apparatus, and has characteristics of the piezoelectric device. A detection unit that detects a value; a determination unit that is provided inside or outside the inkjet recording apparatus; determines whether or not the characteristic value satisfies a predetermined condition; and the inkjet based on a determination result in the determination unit And a control unit that puts the recording apparatus into an operable state or an inoperable state.

  Preferably, the apparatus further includes a storage device capable of storing at least the characteristic value.

  Preferably, the apparatus further includes a measuring unit that measures at least a predetermined amount of liquid consumption in the liquid container.

  Preferably, the detection unit detects vibration characteristic values of at least two of the piezoelectric devices provided in the liquid container, and the determination unit detects relative vibration characteristic values of the at least two piezoelectric devices. The consumption state of the liquid in the liquid container is determined based on the general conditions.

  Hereinafter, the present invention will be described through embodiments of the invention. However, the following embodiments do not limit the claimed invention, and all combinations of features described in the embodiments are the solution of the invention. It is not always essential to the means.

  The basic concept of the present invention includes the state of the liquid in the liquid container (the presence / absence of the liquid in the liquid container, the amount of the liquid, the level of the liquid, the type of the liquid, the composition of the liquid by utilizing the vibration phenomenon) ) Is detected. Several methods are conceivable for detecting the state of the liquid in the liquid container using a specific vibration phenomenon. For example, the elastic wave generating means generates an elastic wave to the inside of the liquid container, and receives a reflected wave reflected by the liquid surface or an opposing wall, thereby detecting a medium in the liquid container and a change in the state thereof. There is a way. In addition, there is a method for detecting a change in acoustic impedance from the vibration characteristics of a vibrating object. As a method of using a change in acoustic impedance, a vibration part of a piezoelectric device or an actuator having a piezoelectric element is vibrated, and then a counter electromotive force generated by residual vibration remaining in the vibration part is measured, whereby a resonance frequency or an inverse is obtained. A method for detecting a change in acoustic impedance by detecting the amplitude of an electromotive force waveform, or measuring a liquid impedance characteristic or an admittance characteristic with an impedance analyzer such as a measuring machine, for example, a transmission circuit, and a change in current value or voltage value or There is a method of measuring a change in current value or voltage value depending on the frequency when vibration is applied to a liquid.

  In addition, the characteristic value of the actuator as an embodiment of the piezoelectric device described below includes at least an element characteristic value and a vibration characteristic value. The element characteristic value means a characteristic value of the piezoelectric material itself included in the actuator. For example, there are electrical characteristics and optical characteristics such as a voltage value, current value, resistance value, and electrical capacity when a constant current or constant voltage is applied to the actuator. The vibration characteristic value means a vibration characteristic of the vibration part that changes based on a change in acoustic impedance due to a change in a medium that contacts the vibration part included in the actuator. For example, there are vibration frequency and amplitude of the vibration part. The characteristic value of the back electromotive force generated by the vibration of the vibration part is also included in the vibration characteristic value.

FIG. 1 is a cross-sectional view of an embodiment of an ink cartridge for a single color, for example, black ink, to which a reference example of the present invention is applied. In this embodiment, FIG. 1 shows a state in which the ink in the ink cartridge is not ejected from the recording head. (The same applies to FIGS. 2 to 5 and FIG. 18.) The ink cartridge of FIG. 1 vibrates the vibration part of the piezoelectric device of the method described above, and then remains in the vibration part. Is based at least on a method for detecting a change in acoustic impedance by measuring the back electromotive force produced by the. An actuator 106 is used as the piezoelectric device.

  The ink cartridge of FIG. 1 includes a container main body 1 that stores ink K, an ink supply port 2 that supplies the ink K in the container main body 1 to the outside of the container main body 1, and the consumption state of the ink K in the container main body 1. And an actuator 106 for detection. The container main body 1 of the ink cartridge according to the present embodiment has a supply port forming side wall 1010 in which the ink supply port 2 is disposed, and an opposing side wall 1015 facing the supply port forming side wall 1010.

  In the ink cartridge according to the present embodiment, the actuator 106 is disposed on the inner wall of the opposing side wall 1015 among the inner walls of the container body 1. The actuator 106 is electrically connected to the lead wire 111 that penetrates the opposing side wall 1015. The external terminal 107 is attached to the outer wall of the opposing side wall 1015 so as to be electrically connected to the lead wire 111. Therefore, although the actuator 106 is disposed on the opposing side wall 1015, the electrical signal is exchanged with the outside by being electrically connected to the external terminal 107 outside the container body 1 via the lead wire 111. can do. The actuator 106 is disposed below the ink level in the unused state of the ink cartridge and in the vicinity of the ink level. Therefore, the vibration part of the actuator 106 is positioned slightly below the ink level.

  By providing the actuator 106 on the inner wall of the container body 1, the actuator 106 does not protrude to the outside. Therefore, the outer shape of the ink cartridge is almost the same as the outer shape of the ink cartridge in which the actuator 106 is not provided, except that the external terminal 107 protrudes. Therefore, there is no significant design change that must be made by physically changing the outer shape of the ink cartridge, such as the standard of the ink cartridge holder of the ink jet recording apparatus.

  In addition, the hole drilled in the inner wall of the container body 1, in this embodiment, the opposing side wall 1015, may be a hole that allows the lead wire 111 to pass therethrough. Therefore, it is not necessary to provide a relatively large hole in the side wall of the container body 1 for allowing the actuator 106 to pass therethrough. Therefore, the inside of the container main body 1 is kept liquid-tight, and ink is prevented from leaking from the inside of the container main body 1 to the outside. As a result, the ink cartridge according to the present embodiment does not require a complicated seal structure. Further, since a complicated seal structure is not required, the manufacturing cost is reduced.

  The element characteristic value can be detected by applying a current or voltage to the actuator 106 via the external terminal 107 and the lead wire 111.

  Further, in the present embodiment, the actuator 106 is disposed below the ink level in the unused state of the ink cartridge and in the vicinity of the ink level, so that when the ink cartridge is manufactured or recycled In this case, it is possible to detect whether a predetermined amount of ink is actually contained in the ink cartridge. Further, after the manufacture of the ink cartridge, the ink amount with a defect may decrease due to ink leakage or ink evaporation. In such a case, the actuator 106 can detect that a predetermined amount of ink is not contained in the ink cartridge, and thus can detect a defect in the ink cartridge.

  Further, when the ink cartridge is left unused for a long period of time, the quality of the ink such as the viscosity of the ink may deteriorate due to the evaporation of the ink. Therefore, the actuator 106 can make a determination of whether the quality is good or not by detecting that a predetermined amount of ink is not contained in the ink cartridge.

  Further, when the ink cartridge is not properly installed or the ink jet recording apparatus is tilted, the actuator 106 is exposed from the ink surface even though the ink cartridge is not used. It can be detected that the ink cartridge is inclined. On the contrary, it may be detected that the ink cartridge is tilted when the actuator 106 is not exposed from the ink surface even though a predetermined amount of ink is consumed.

  The amount of ink filled in the ink cartridge, the inclination of the ink cartridge, or the amount of decrease in ink that determines that the ink cartridge is defective can be changed according to the height of the ink liquid surface on which the actuator 106 is provided. Note that an oscillation means may be provided separately, and the actuator 106 may be simply used as a medium detection means.

FIG. 2 shows another embodiment of an ink cartridge according to a reference example of the present invention. In the ink cartridge according to the present embodiment, the actuator 106 is disposed on the opposite side wall 1015 in the same manner as the ink cartridge according to the embodiment of FIG. In the ink cartridge according to the present embodiment, the actuator 106 is disposed slightly above the ink level when the ink cartridge is not used.

  Also in the present embodiment, the element characteristic value can be detected by applying a current or voltage to the actuator 106 via the external terminal 107 and the lead wire 111.

  In addition, when the ink cartridge is not properly installed or the ink jet recording apparatus is tilted, the ink cartridge is tilted when the actuator 106 detects ink even though the ink cartridge is not used. Can be detected.

  FIG. 3A shows yet another embodiment of an ink cartridge according to the present invention. In the ink cartridge according to the present embodiment, a plurality of actuators 106 a and 106 b are arranged on the opposing side wall 1015. The actuators 106a and 106b are disposed slightly below the ink level when the ink cartridge is not used and near the boundary between the bottom surface 1a of the container body 1 and the opposing side wall 1015, respectively.

  Therefore, the same effect as the actuator 106 in the embodiment of FIG. 1 can be obtained. On the other hand, the actuator 106b is provided so that the medium in contact with the actuator 106b changes from ink to gas at the ink end stage when the ink is consumed. Therefore, the actuator 106b can detect the ink end.

  Therefore, as in the embodiment of FIG. 3A, by providing two actuators 106a and 106b, it is determined whether or not the actuators 106a and 106b are defective, and a predetermined amount of ink enters the ink cartridge. Detection of whether or not, and ink end detection can all be performed.

  Further, the ink consumption amount in the ink cartridge can be detected based on the relative condition of the characteristic values of the actuator 106a and the actuator 106b. More specifically, the semiconductor storage means 7 stores the vibration characteristic value of the actuator 106a detected when a predetermined amount of ink in the ink cartridge is consumed and the ink is exhausted around the actuator 106a. When the value of the vibration characteristic value detected by the actuator 106b becomes substantially equal to the value of the vibration characteristic value of the actuator 106a detected when the ink has run out around the actuator 106a, the liquid level of the ink is It can be determined that 106b has been passed. Since the actuator 106b is disposed in the vicinity of the ink liquid level at the time of the ink end of the container main body 1, it can be determined that the ink end is reached when it is determined that the ink liquid level has passed through the actuator 106b. Further, according to the present embodiment, it is not necessary to measure the vibration characteristic values of the actuators 106a and 106b when there is no ink in the container body 1 in the manufacturing process. Therefore, the actuators 106a and 106b or the ink cartridge can be easily manufactured, and the manufacturing process is shortened. Furthermore, the actuator 106a and the actuator 106b are preferably manufactured in the same lot. This is because the characteristics of the actuator 106a and the actuator 106b are substantially equal. By using the actuator 106a and the actuator 106b having the same characteristics, the ink in the ink cartridge can be accurately detected.

FIG. 3B shows still another embodiment of an ink cartridge according to a reference example of the present invention. In the ink cartridge according to the embodiment of FIG. 3B, the actuator 106b of the ink cartridge according to the embodiment of FIG. 3A is disposed in the vicinity of the actuator 106a. The positions of the actuator 106a and the actuator 106b are designed so that the ink level is positioned between the actuator 106a and the actuator 106b when the ink cartridge is mounted on the ink jet recording apparatus. Thereby, it can be determined that the ink cartridge is normally mounted in the ink jet recording apparatus. When the ink cartridge is installed in the ink jet recording apparatus, the actuator 106a detects that there is no ink, and if the actuator 106b detects that there is ink, it is determined that the ink cartridge is installed normally. On the other hand, when both the actuator 106a and the actuator 106b detect that ink is present when the ink cartridge is mounted on the ink jet recording apparatus, it is determined that the ink cartridge is not normally mounted. Further, when the ink cartridge is mounted on the ink jet recording apparatus, if both the actuator 106a and the actuator 106b detect that there is no ink, the ink in the ink cartridge is not filled with a predetermined amount, or the ink It can be determined that the cartridge, the actuator, and the sub tank unit 33 (see FIG. 7) are defective.

  Further, when the ink cartridge according to the embodiment of FIG. 3B is filled with ink, the ink cartridge may be filled until the ink level is located between the actuator 106a and the actuator 106b. When the actuator 106a detects the absence of ink and the actuator 106b detects the presence of ink, it can be detected that the ink is filled in the ink cartridge without excess or deficiency.

  Although the actuator 106 in the embodiment of FIGS. 1 to 3B is provided on the opposing side wall 1015, the actuator 106 may be provided on the supply port forming side wall 1010. In addition, as shown in FIG. 18, the actuator 106 may be provided on the top wall above the container body 1. Further, when the two actuators 106 are arranged so as to be located at the same liquid level with respect to the ink liquid level, only one of the actuators 106 is gas when the ink cartridge is arranged inclined. Alternatively, since the ink is detected, it can be detected that the ink cartridge is inclined.

FIG. 4 is a cross-sectional view in the short-side direction of still another embodiment of the ink cartridge according to the reference example of the invention. The container body 1 includes an intervening side wall 1020a interposed between a supply port forming side wall 1010 (see FIG. 1) where the ink supply port 2 is disposed and an opposing side wall 1015 (see FIG. 1) facing the supply port forming side wall 1010. 1020b. In this embodiment, the actuator 106 is disposed on the intervening side wall 1020a.

  In the present embodiment, the actuator 106 is disposed on the inner wall of the intervening side wall 1020a slightly below the ink level when the ink cartridge is not used. However, the actuator 106 may be provided as shown in FIGS. 1 to 3B. Furthermore, in this embodiment, the actuator 106 is disposed on one intervening side wall 1020a, but may be disposed on the other intervening side wall 1020b.

FIG. 5 is a cross-sectional view of an ink cartridge provided with a single actuator 106 having a long vibration region as an embodiment of a reference example of the present invention . The vibration region of the actuator 106 extends from the vicinity of the ink surface before the ink is consumed to the bottom surface 1a.

  According to the present embodiment, all of the determination of whether or not the actuator 106 is defective, whether or not the ink cartridge has a predetermined amount of ink, and the detection of the ink end are all performed by the single actuator 106. Enable implementation.

  Further, the consumption state of the liquid in the container can be determined based on at least two vibration characteristic values of the actuator 106.

  FIG. 6 is a perspective view seen from the back side showing an embodiment of an ink cartridge containing a plurality of types of ink. The container 8 is divided into three ink chambers 9, 10 and 11 by a partition wall. Ink supply ports 12, 13 and 14 are formed in the respective ink chambers. Actuators 15, 16 and 17 are provided on the supply port forming side walls 1012, 1013 and 1014, respectively. The actuators 15, 16 and 17 may be provided on other side walls included in the container body 1.

  FIG. 7 is a cross-sectional view showing an embodiment of a main part of an ink jet recording apparatus using the ink cartridge shown in FIG. The carriage 30 that can reciprocate in the width direction of the recording paper includes a sub tank unit 33. The recording head 31 is provided on the lower surface of the sub tank unit 33. The ink supply needle 32 is provided on the ink cartridge mounting surface side of the sub tank unit 33. Furthermore, a panel 2000 as an output unit that displays an error when at least the characteristic value of the actuator 106 does not satisfy a predetermined condition is provided in the ink jet recording apparatus. Alternatively, an external output terminal 2500 connected to the host computer 3000 may be provided in the inkjet recording apparatus so that an error is displayed on the external host computer 3000. In FIG. 7, the external terminal 107 is electrically or optically connected to the external output terminal 2500 via a cartridge holder (not shown in FIG. 7) of the ink jet recording apparatus.

  When the ink supply port 2 of the container body 1 is inserted into the ink supply needle 32 of the sub tank unit 33, the valve body 6 moves backward against the spring 5, an ink flow path is formed, and the ink in the container body 1 is transferred to the ink chamber. 34. After the ink chamber 34 is filled with ink, a negative pressure is applied to the nozzle openings of the recording head 31 to discharge the ink from the recording head 31 and execute a recording operation.

  In the embodiment shown in FIGS. 1 to 5 and FIG. 18, when the ink cartridge is installed in the ink jet recording apparatus and the ink chamber 34 is filled with ink, the ink level is set to the position shown in the drawing. It is preferable to design the cartridge, the position of the actuator 106 and the capacity of the ink chamber 34. Accordingly, the liquid level of the ink shown in FIGS. 1 to 5 and FIG. 18 is not necessarily the level of the liquid level when the ink cartridge is manufactured.

  When ink is consumed in the recording head 31 by the recording operation, the pressure on the downstream side of the membrane valve 36 is reduced, so that the membrane valve 36 is opened. By opening the membrane valve 36, the ink in the ink chamber 34 flows into the recording head 31 via the ink supply path 35. As the ink flows into the recording head 31, the ink in the container body 1 flows into the sub tank unit 33 via the ink supply needle 32, and printing is repeated.

  FIG. 8 is a block diagram showing a control device of the ink jet recording apparatus of the present invention. The ink jet recording apparatus of the present invention includes a recording head 702 that discharges ink droplets onto a recording sheet for printing, a carriage 700 that reciprocates the recording head 702 in the width direction (main scanning direction) of the recording sheet, and a carriage 700 that is mounted. And an ink cartridge 180 for supplying ink to the recording head 702. The carriage 700 is connected to a carriage drive motor 716. Driving the carriage drive motor 716 causes the carriage 700 and the recording head 702 to reciprocate in the width direction of the recording paper. The carriage motor control unit 722 controls the carriage drive motor 716.

  The actuator 106 mounted on the ink cartridge 180 is controlled by the piezoelectric device control means 720. The characteristic value of the actuator 106 controlled by the piezoelectric device control means 720 is detected by the characteristic value detection unit 810. For example, when the piezoelectric device control unit 720 applies a constant voltage to the actuator 106, the characteristic value detection unit 810 detects the value of the current flowing through the piezoelectric element included in the actuator 106. Thereby, the characteristic value detector 810 can detect the resistance value of the piezoelectric element. Further, by using an AC power supply, the characteristic value detection unit 810 may detect the electric capacity of the piezoelectric element.

  The characteristic value detection unit 810 may detect the vibration characteristic of the vibration unit of the actuator 106. For example, the piezoelectric device control unit 720 applies a voltage to the actuator 106, and the characteristic value detection unit 810 detects the back electromotive force generated by the residual vibration remaining in the vibration unit of the actuator 106. Thereby, the characteristic value detection unit 810 can detect the resonance frequency of the residual vibration and the amplitude of the back electromotive force.

  The characteristic value of the actuator 106 detected by the characteristic value detection unit 810 is transmitted to the characteristic value determination unit 820. On the other hand, a predetermined condition to be satisfied by the characteristic value is stored in the storage unit 850 in advance. The predetermined condition may be set according to the characteristic value. For example, when the characteristic value is a resistance value of a piezoelectric element, a spec that the resistance value of the piezoelectric element should satisfy is set as a predetermined condition. For example, when the characteristic value is determined as the resonance frequency of the actuator 106, a specification that the resonance frequency should satisfy is set as a predetermined condition. Corresponding to the timing when the characteristic value detection unit 810 detects the characteristic value of the actuator 106, the storage unit 850 transmits a predetermined condition to the characteristic value determination unit 820. The characteristic value transmitted to characteristic value determination unit 820 is compared with a predetermined condition by a comparator included in characteristic value determination unit 820.

  When the characteristic value determination unit 820 determines that the characteristic value does not satisfy the predetermined condition, the characteristic value determination unit 820 transmits an error signal to the output unit 840. The output unit 840 outputs an error display according to the error signal. The output unit 840 is, for example, the panel 2000 or the external output terminal 2500 shown in FIG. The external output terminal 2500 is connected to the host computer 3000 so that an error signal can be output to the external host computer 3000. The error display is a display indicating that the ink cartridge is defective, the ink cartridge should be replaced, a characteristic value, a determination result in the characteristic value determination unit 820, and the like. The error display may be simply means for generating light or means for generating sound. Further, the characteristic value determination unit 820 transmits an inoperable signal to the control unit 750. The inoperable signal is a signal for causing the ink jet recording apparatus not to perform operations such as printing, cleaning, and flushing, that is, a signal for disabling the ink jet recording apparatus. The ink jet recording apparatus that has received the inoperable signal does not execute the operation or stops the operation. It may be designed so that the user can select to operate the ink jet recording apparatus when the ink jet recording apparatus is in an inoperable state (not shown).

  On the other hand, when the characteristic value determination unit 820 determines that the characteristic value satisfies a predetermined condition, the characteristic value determination unit 820 transmits an operable signal to the control unit 750. The operable signal is a signal for enabling the ink jet recording apparatus to execute operations such as printing, cleaning, flushing, standby, etc., that is, a signal for making the ink jet recording apparatus operable. The inkjet recording apparatus that has received the operation enable signal can start or restart the operation, or enters a standby state before the operation. Further, the output unit 840 may output a display notifying that the characteristic value satisfies a predetermined condition and that the ink jet recording apparatus is operable.

  The timing at which the characteristic value detection unit 810 detects the characteristic value of the actuator 106 may be when the ink cartridge is mounted on the ink jet recording apparatus. Alternatively, the ink consumption measuring unit 830 may measure that a predetermined amount of ink in the ink cartridge has been consumed.

  The time when the ink consumption measuring unit 830 measures that a predetermined amount of ink in the ink cartridge has been consumed will be described in more detail. The ink consumption measuring unit 830 calculates the amount of ink consumed in the ink cartridge by integrating the amount of ink droplets ejected from the recording head and the amount of ink used during cleaning and flushing. Information on the calculation consumption of ink measured by the ink consumption measurement unit 830 is transmitted to the characteristic value determination unit 820. On the other hand, a predetermined condition to be satisfied by the calculated consumption amount is stored in the storage unit 850 in advance. The predetermined condition may be set according to the amount of ink droplets ejected from the recording head, the frequency of cleaning or flushing, the position where the actuator 106 is provided, and the like. The storage unit 850 transmits the stored predetermined condition to the characteristic value determination unit 820. The characteristic value determination unit 820 issues a signal to the control unit 750 when the ink consumption calculated by the ink consumption measurement unit 830 reaches a predetermined amount. The piezoelectric device control means 720 of the control unit 750 gives a voltage or the like to the actuator 106 in accordance with a signal from the characteristic value determination unit 820. Thereby, the characteristic value detector 810 detects the characteristic value of the actuator 106.

  Note that the amount of ink droplets set in advance in the ink consumption measuring unit 830 and the amount of ink used during cleaning and flushing may vary depending on the amount of ink actually ejected and the usage environment. Many. Therefore, it is preferable that the predetermined condition stored in the storage unit 850 is obtained by adding or subtracting a certain amount of surplus. Further, when the characteristic value of the actuator 106 is detected when the ink cartridge is mounted on the ink jet recording apparatus, the ink consumption as a predetermined condition stored in the storage unit 850 may be set to zero.

  The ink jet recording apparatus further includes a cap 712 that seals the recording head 702 in the non-printing area. The cap 712 is connected to the suction pump 718 via a tube, and cleans the nozzle openings of the recording head 702 by discharging ink from all the nozzles of the recording head 702 in response to supply of negative pressure. Alternatively, flushing is performed by positioning the recording head 702 on the cap 712 and ejecting ink from all nozzles of the recording head 702. The timing of detecting the characteristic value of the actuator 106 may be the time when these cleaning processing, flushing processing, and switching between the printing state and the non-printing state are performed.

  The characteristic value detection unit 810, the characteristic value determination unit 820, the ink consumption measurement unit 830, the output unit 840, and the storage unit 850 may be disposed inside the ink jet recording apparatus, for example, inside the control unit 750. It may be deployed on an externally deployed device, such as an external host computer. Preferably, the characteristic value detection unit 810, the characteristic value determination unit 820, the ink consumption measurement unit 830, the output unit 840, and the storage unit 850 involved in the operation of the piezoelectric device are arranged in the ink cartridge. This is because it is preferable to consider a case where a member involved in the operation of the piezoelectric device breaks down so that it can be replaced simultaneously with the ink cartridge. Furthermore, the characteristic value detection unit 810, the characteristic value determination unit 820, the ink consumption measurement unit 830, the output unit 840, and the storage unit 850 that are involved in the operation of the piezoelectric device are mounted so as to be easily removable from the ink jet recording apparatus. The recording head may be provided.

  9 and 10 are flowcharts showing a control method of the ink jet recording apparatus in which the ink cartridge according to the embodiment of FIG. 1 is mounted. The ink cartridge according to the embodiment of FIGS. 2 to 6 may be used in place of the ink cartridge according to the embodiment of FIG.

  FIG. 9 is a flow from when the ink cartridge shown in FIG. 1 is mounted to the ink jet recording apparatus to when the ink jet recording apparatus becomes operable or inoperable.

  Based on the flow of FIG. 9, the operation of the ink jet recording apparatus will be described with reference to FIG. An ink cartridge is attached to the ink jet recording apparatus. When the ink cartridge is attached, the ink jet recording apparatus recognizes that the ink cartridge is attached. The means for recognizing that the ink cartridge is installed is not particularly limited. For example, the ink jet recording apparatus may recognize that the ink cartridge is mounted by detecting the semiconductor storage means 7 provided in the ink cartridge. Further, a protrusion (not shown) is provided on the ink cartridge, and when the ink cartridge is mounted, the protrusion presses a switch (not shown) provided in advance in the ink jet recording apparatus. Thereby, the switch is electrically connected, and the ink jet recording apparatus may recognize that the ink cartridge is mounted. Alternatively, when the ink cartridge is mounted, the user may input to the ink jet recording apparatus by any means.

  Next, the piezoelectric device control means 720 transmits an element characteristic detection signal for detecting an element characteristic value of the actuator 106 to the actuator 106. The element characteristic detection signal is, for example, current or voltage. Thereafter, in FIG. 9A, the characteristic value detection unit 810 detects the element characteristic value of the actuator 106, and the characteristic value determination unit 820 determines the element characteristic value.

  When the element characteristic value of the actuator 106 does not satisfy the predetermined condition, an error 0 is displayed on the output unit 840. For example, error 0 is displayed on a panel 2000 as a display unit provided in the ink jet recording apparatus or on an external host computer 3000 connected to an external output terminal 2500 provided in the ink jet recording apparatus. Alternatively, the command S0 for transmitting the element characteristic detection signal to the actuator 106 may be returned to the ink jet recording apparatus again. In such a case, the actuator 106 is set to output an error 0 display when the element characteristic value does not satisfy the predetermined condition even though the element characteristic detection signal is transmitted a predetermined number of times by the command S0. May be. Further, it may be set so that an error 0 display is output when the average value of the element characteristic values of the actuator 106 when the element characteristic detection signal is transmitted a predetermined number of times does not satisfy a predetermined condition. Further, the determination can be made based on whether the maximum value among the plurality of element characteristic values is within a predetermined range or whether the minimum value is within the predetermined range.

  The display of error 0 may be a display that simply notifies the user that an error has occurred. Preferably, the display of error 0 is an indication that the actuator 106 is defective, an element characteristic value, a determination result in the characteristic value determination unit 820, or the like. While error 0 is displayed, the ink jet recording apparatus becomes inoperable. The output unit 840 may display that the ink jet recording apparatus is in an inoperable state. Further, the storage unit 850 may store information indicating that the ink jet recording apparatus is in an inoperable state. Thereby, past data of the ink jet recording apparatus is stored. The inoperable state is a state in which the operation as a recording apparatus is impossible.

  In addition, the ink jet recording apparatus according to the present embodiment has a signal for moving the ink cartridge to a predetermined position so that the ink cartridge can be replaced with a new ink cartridge even when it is in an inoperable state. It is in a state where a signal such as selection by can be received.

  As the defect in the element characteristic value of the actuator 106, a defect in the piezoelectric element and a contact failure in the wiring to the piezoelectric element are considered. The defect of the piezoelectric element occurs because the element characteristic itself of the piezoelectric element is defective. 11A, 11B, and 11C, the electrical contact between the piezoelectric layer 160, the upper electrode 164, the lower electrode 166, the upper electrode terminal 168, the lower electrode terminal 170, and the auxiliary electrode 172 in FIG. 11A, FIG. 11B, and FIG. This occurs because the electrical contact between the actuator 106 and the characteristic value detection unit 810 is disconnected.

  Based on the display of error 0, the user replaces the ink cartridge while maintaining the ink jet recording apparatus in an inoperable state. Alternatively, it may be set so that the user can select the command S2 in order to make the ink jet recording apparatus operable with an already mounted ink cartridge. The ink jet recording apparatus can be operated by the command S2. It is preferable to store past errors and command contents including the element characteristic values of the actuator 106 in the storage unit 850.

  When the element characteristic value of the actuator 106 satisfies a predetermined condition, an operation signal is transmitted from the piezoelectric device control means 720 to the actuator 106 (see FIG. 9B). The actuator 106 receives an operation signal. If the actuator 106 is not defective, the actuator 106 performs a predetermined operation. On the other hand, when the actuator 106 is defective, the actuator 106 does not perform a predetermined operation. Whether or not the actuator 106 has performed a predetermined operation can be determined by the characteristic value determination unit 820 determining whether or not the characteristic value detection unit 810 has detected the vibration characteristic of the actuator 106.

  In FIG. 9B, when the actuator 106 does not perform a predetermined operation, an error 1 display is output to the output unit 840. When the actuator 106 does not perform a predetermined operation, a command S1 for transmitting an operation signal to the actuator 106 may be returned to the ink jet recording apparatus again. In such a case, it may be set so that the display of error 1 is output when the actuator 106 does not operate even though the operation signal is transmitted a predetermined number of times by the command S1.

  The display of error 1 may be a display that simply notifies the user that an error has occurred. Preferably, the display of error 1 is a display indicating that the ink cartridge is defective or that the actuator 106 provided in the ink cartridge is defective, a characteristic value, a determination result in the characteristic value determination unit 820, and the like. It is also possible to display an error 1 that an ink cartridge not provided with the actuator 106 is mounted on the ink jet recording apparatus. When the actuator 106 does not perform a predetermined operation, the error 1 is displayed and the ink jet recording apparatus becomes inoperable.

  The user replaces the ink cartridge while maintaining the inoperable state based on the error 1 display. Alternatively, it may be set so that the user can select the command S2 in order to make the ink cartridge ready for operation. The inkjet recording apparatus can be operated by the command S2. It is preferable to store past errors and commands in the storage unit 850.

  In FIG. 9B, when the actuator 106 performs a predetermined operation, it is determined whether the initial vibration characteristic value obtained from the residual vibration detected by the actuator 106 satisfies a predetermined condition. The initial vibration characteristic value includes the resonance frequency, amplitude, wavelength, wave number within a predetermined time, time until the predetermined wave number elapses, and the like of the back electromotive force generated by the residual vibration remaining in the vibration part of the actuator 106. More details are shown in FIGS. 11A to 19B. Further, the predetermined condition is a range in which a certain margin is added to or subtracted from the expected value of the initial vibration characteristic value, or a range in which a certain margin is added to or subtracted from the actual measurement value of the characteristic value measured in advance when the actuator 106 or the ink cartridge is manufactured. Measured values may be included. The predetermined condition may be a condition that defines only an upper limit or a lower limit.

  In FIG. 9C, when the value of the initial vibration characteristic value does not satisfy the predetermined condition, a display of error 2 is output to the output unit 840. Further, when the initial vibration characteristic value does not satisfy the predetermined condition, the command S3 for transmitting the operation signal to the actuator 106 may be returned to the ink jet recording apparatus again. In such a case, determination can be made based on an average value, a maximum value, or a minimum value of a plurality of initial vibration characteristic values obtained by operating the actuator 106 a predetermined number of times. When the average value, the maximum value, or the minimum value of the plurality of initial vibration characteristic values is not within the predetermined range, the error 2 display can be set to be output.

  The display of error 2 may be a display that simply notifies the user that an error has occurred. More preferably, the display of error 2 is a display of the ink cartridge being defective, the characteristic value, and the determination result in the characteristic value determination unit 820. As an ink cartridge failure due to the display of error 2, for example, when the ink level does not reach the position of the actuator 106 because the ink does not enter a predetermined amount at the time of manufacturing the ink cartridge, the ink cartridge or the ink jet If the ink is not present around the actuator 106 because the recording apparatus is inclined, the ink is evaporated when the ink cartridge is left unused for a long period of time, and the ink level reaches the position of the actuator 106. If there is no ink, the ink may leak or evaporate due to a defect in the ink cartridge, the ink level may not reach the actuator 106, or the ink cartridge once used may be remounted in the inkjet recording apparatus. When the initial vibration characteristic value does not satisfy the predetermined condition, error 2 is displayed and the ink jet recording apparatus is in a non-printable state.

  The user replaces the ink cartridge according to the display of error 2 while maintaining the ink jet recording apparatus in a non-printable state. Alternatively, it may be set so that the user can select the command S2 in order to make the ink cartridge ready for operation. The inkjet recording apparatus can be operated by the command S2. It is preferable to store past errors and commands in the storage unit 850.

  In FIG. 9C, when the initial vibration characteristic value satisfies a predetermined condition, the ink jet recording apparatus is in an operable state.

  FIG. 9 shows a flow when the ink cartridge is mounted on the ink jet recording apparatus. However, the flow of FIG. 9 may be executed immediately before the inkjet recording apparatus starts its operation. 9 may be executed when the ink jet recording apparatus is in a non-printing state. Furthermore, the flow of FIG. 9 may be executed when cleaning, flushing, and wiping the recording head. Furthermore, the flow of FIG. 9 may be executed at an appropriate time set in advance.

  FIG. 10 is a flow from when the ink is consumed by a predetermined amount until the characteristic value of the actuator 106 is detected and the ink jet recording apparatus becomes operable.

  Based on the flow of FIG. 10, the operation of the ink jet recording apparatus will be described with reference to FIG.

  The flow of FIG. 10 may be started in the operation of the ink jet recording apparatus, for example, every time a page break occurs, every time a transition to a non-printing state, or every elapse of a preset time.

  The ink consumption measuring unit 830 counts the number of ink droplets ejected by the recording head and the number of times of maintenance, for example, flushing and cleaning, for recovering clogging and meniscus of nozzles provided in the recording head. The amount of ink ejected by the head is measured.

  The measured value of the amount of ink ejected by the recording head substantially matches the amount of ink consumed in the ink cartridge. If the measured value of ink consumption does not reach the predetermined reference value, the ink jet recording apparatus continues to operate. When the measured value of the ink consumption reaches a predetermined value, the ink jet recording apparatus transmits an operation signal to the actuator 106. The predetermined reference value is preferably adjusted by adding or subtracting the margin to the reference value in consideration of the difference between the actual ink consumption and the measured value of the amount of ink ejected by the recording head 31.

  The actuator 106 receives an operation signal. If the actuator 106 is not defective, the actuator 106 performs a predetermined operation. On the other hand, when the actuator 106 is defective, the actuator 106 does not perform a predetermined operation (see FIG. 10A). Whether or not the actuator 106 has performed a predetermined operation can be determined by the characteristic value determination unit 820 determining whether or not the characteristic value detection unit 810 has detected the vibration characteristic of the actuator 106.

  In FIG. 10A, when the actuator 106 does not perform a predetermined operation, error 3 is displayed on the output unit 840. Further, when the actuator 106 does not perform a predetermined operation, a command S4 for transmitting an operation signal to the actuator 106 may be returned to the ink jet recording apparatus again. In such a case, setting is made so that the display of error 3 is output when the actuator 106 does not operate even though the operation signal is transmitted a predetermined number of times by the command S4.

  The display of error 3 may be a display that simply notifies the user that an error has occurred. Preferably, the display of error 3 indicates that the ink cartridge is defective, the actuator 106 provided in the ink cartridge is defective, the ink jet recording apparatus is stopped, and the determination result in the characteristic value / characteristic value determination unit 820. And so on. It is also possible to display an error 3 that an ink cartridge not provided with the actuator 106 has been installed in the ink jet recording apparatus. When the actuator 106 does not perform a predetermined operation, an error 3 is displayed and the ink jet recording apparatus becomes inoperable.

  The user replaces the ink cartridge while the ink jet recording apparatus is kept in an inoperable state according to the error 3 display. Alternatively, it may be set so that the user can select the command S5 in order to continue printing with the already installed ink cartridge. The ink jet recording apparatus becomes operable by the command S5. It is preferable to store past errors and commands in the storage unit 850.

  10A, when the actuator 106 performs a predetermined operation, it is determined whether or not the intermediate vibration characteristic value obtained from the residual vibration detected by the actuator 106 satisfies a predetermined condition (FIG. 10B )). The intermediate vibration characteristic value includes the resonance frequency, amplitude, wavelength, wave number within a predetermined time, time until the predetermined wave number elapses, and the like of the back electromotive force generated by the residual vibration remaining in the vibration part of the actuator 106. When the initial vibration characteristic value is measured, the intermediate vibration characteristic value is preferably the same type of characteristic value as the initial vibration characteristic value. The predetermined condition to be satisfied by the intermediate vibration characteristic value is constant within the range obtained by adding or subtracting a certain margin to the expected value of the intermediate vibration characteristic value, or the actual measurement value of the characteristic value measured in advance when the actuator 106 or the ink cartridge is manufactured. The intermediate vibration characteristic value can be included in a range determined by adding or subtracting the amount of noise or another characteristic value, for example, a range determined by the relative relationship with the initial vibration characteristic value described above. The predetermined condition may define only an upper limit or a lower limit. Further, the predetermined condition that the intermediate vibration characteristic value should satisfy may be the same as the condition that the initial vibration characteristic value should satisfy. The initial vibration characteristic value and the intermediate vibration characteristic value may be one and the other of at least two vibration characteristic values detected from the single actuator 106. Further, the characteristic value detected by the characteristic value detection unit 810 and determined by the characteristic value determination unit 820 may be a single type of characteristic value or a plurality of types of characteristic values.

  In FIG. 10B, when the intermediate vibration characteristic value does not satisfy the predetermined condition, error 4 is displayed on the output unit 840. Further, the command S6 for transmitting the operation signal to the actuator 106 may be returned to the ink jet recording apparatus again. In such a case, the determination can be made based on an average value, a maximum value, or a minimum value of a plurality of intermediate vibration characteristic values obtained by operating the actuator 106 a predetermined number of times. When the average value, maximum value, or minimum value of the plurality of intermediate vibration characteristic values does not satisfy the predetermined condition, the output unit 840 is set to output the error 4 display.

  The display of error 4 may be a display that simply notifies the user that the error is present. Preferably, the display of error 4 is a display indicating that the ink cartridge is defective, a characteristic value, and a determination result in the characteristic value determination unit 820. For example, when the ink cartridge or the ink jet recording apparatus is inclined and the ink is in the vicinity of the actuator 106, the ink cartridge is not supplied from the ink cartridge to the recording head. In some cases, ink is not ejected due to a defect in the recording head. When the intermediate vibration characteristic value does not satisfy the predetermined condition, an error 4 is displayed and the ink jet recording apparatus becomes inoperable.

  The user replaces the ink cartridge while the ink jet recording apparatus is kept in an inoperable state by displaying the error 4. Alternatively, it may be set so that the user can select the command S5 in order to resume the operation with the already mounted ink cartridge. The ink jet recording apparatus becomes operable by the command S5. It is preferable to store past errors and commands in the storage unit 850.

  In FIG. 10B, when the value of the intermediate vibration characteristic value satisfies a predetermined condition, the ink jet recording apparatus becomes operable.

  Each of the embodiments of FIGS. 9 and 10 may execute only the control method of one ink jet recording apparatus. Moreover, you may implement embodiment of FIG. 9 and FIG. 10 as a series of control methods of an inkjet recording device.

  11A to 12 show details and an equivalent circuit of the actuator 106 which is an embodiment of the piezoelectric device. The actuator here is used in a method of detecting a consumption state of a liquid in a liquid container by detecting at least a change in acoustic impedance. In particular, it is used in a method for detecting a consumption state of liquid in a liquid container by detecting at least a change in acoustic impedance by detecting a resonance frequency by residual vibration. FIG. 11A is an enlarged plan view of the actuator 106. FIG. 11B shows a BB cross section of the actuator 106. FIG. 11C shows a CC cross section of the actuator 106. Further, FIGS. 12A and 12B show an equivalent circuit of the actuator 106. FIGS. 12C and 12D show the periphery including the actuator 106 and its equivalent circuit when the ink is filled in the ink cartridge, respectively, and FIGS. 12E and 12F. ) Shows the periphery including the actuator 106 and its equivalent circuit when there is no ink in the ink cartridge.

  The actuator 106 includes a substrate 178 having a circular opening 161 at the substantially center, a vibration plate 176 provided on one surface (hereinafter referred to as “surface”) of the substrate 178 so as to cover the opening 161, Piezoelectric layer 160 disposed on the surface side of plate 176, upper electrode 164 and lower electrode 166 sandwiching piezoelectric layer 160 from both sides, upper electrode terminal 168 electrically coupled to upper electrode 164, and lower electrode 166 It has a lower electrode terminal 170 that is electrically coupled, and an auxiliary electrode 172 that is disposed between the upper electrode 164 and the upper electrode terminal 168 and that electrically couples them. The piezoelectric layer 160, the upper electrode 164, and the lower electrode 166 each have a circular portion as a main part. Each circular portion of the piezoelectric layer 160, the upper electrode 164, and the lower electrode 166 forms a piezoelectric element.

  The diaphragm 176 is formed on the surface of the substrate 178 so as to cover the opening 161.

  The cavity 162 is formed by a portion facing the opening 161 of the vibration plate 176 and the opening 161 on the surface of the substrate 178. The surface of the substrate 178 opposite to the piezoelectric element (hereinafter referred to as “back surface”) faces the liquid container side, and the cavity 162 is configured to come into contact with the liquid. The diaphragm 176 is liquid-tightly attached to the substrate 178 so that the liquid does not leak to the surface side of the substrate 178 even if the liquid enters the cavity 162.

  The lower electrode 166 is located on the surface of the vibration plate 176, that is, the surface opposite to the liquid container, and is attached so that the center of the circular portion which is the main part of the lower electrode 166 and the center of the opening 161 are substantially coincided with each other. It has been. The area of the circular portion of the lower electrode 166 is set to be smaller than the area of the opening 161. On the other hand, on the surface side of the lower electrode 166, the piezoelectric layer 160 is formed so that the center of the circular portion and the center of the opening 161 substantially coincide. The area of the circular portion of the piezoelectric layer 160 is set to be smaller than the area of the opening 161 and larger than the area of the circular portion of the lower electrode 166.

  On the other hand, on the surface side of the piezoelectric layer 160, the upper electrode 164 is formed so that the center of the circular portion which is the main part thereof substantially coincides with the center of the opening 161. The area of the circular portion of the upper electrode 164 is set to be smaller than the area of the circular portion of the opening 161 and the piezoelectric layer 160 and larger than the area of the circular portion of the lower electrode 166.

  Accordingly, the main part of the piezoelectric layer 160 is structured to be sandwiched between the main part of the upper electrode 164 and the main part of the lower electrode 166 from the front surface side and the back surface side, respectively. Deformation drive is possible. The circular portions that are the main portions of the piezoelectric layer 160, the upper electrode 164, and the lower electrode 166 form a piezoelectric element in the actuator 106. As described above, the piezoelectric element is in contact with the diaphragm 176. Of the circular portion of the upper electrode 164, the circular portion of the piezoelectric layer 160, the circular portion of the lower electrode 166, and the opening 161, the opening 161 has the largest area. With this structure, the vibration region of the diaphragm 176 that actually vibrates is determined by the opening 161. Further, since the circular portion of the upper electrode 164, the circular portion of the piezoelectric layer 160, and the circular portion of the lower electrode 166 have a smaller area than the opening 161, the diaphragm 176 is more likely to vibrate. Furthermore, of the circular portion of the lower electrode 166 and the circular portion of the upper electrode 164 that are electrically connected to the piezoelectric layer 160, the circular portion of the lower electrode 166 is smaller. Accordingly, the circular portion of the lower terminal 166 determines the portion of the piezoelectric layer 160 that generates the piezoelectric effect.

  The upper electrode terminal 168 is formed on the surface side of the diaphragm 176 so as to be electrically connected to the upper electrode 164 via the auxiliary electrode 172. On the other hand, the lower electrode terminal 170 is formed on the surface side of the diaphragm 176 so as to be electrically connected to the lower electrode 166. Since the upper electrode 164 is formed on the surface side of the piezoelectric layer 160, it is necessary to have a step equal to the sum of the thickness of the piezoelectric layer 160 and the thickness of the lower electrode 166 in the middle of connection with the upper electrode terminal 168. It is difficult to form the step with only the upper electrode 164, and even if possible, the connection state between the upper electrode 164 and the upper electrode terminal 168 becomes weak and there is a risk of disconnection. Therefore, the upper electrode 164 and the upper electrode terminal 168 are connected using the auxiliary electrode 172 as an auxiliary member. By doing so, the piezoelectric layer 160 and the upper electrode 164 are both supported by the auxiliary electrode 172, and a desired mechanical strength can be obtained, and the connection between the upper electrode 164 and the upper electrode terminal 168 is ensured. It becomes possible to.

  The vibration region facing the piezoelectric element in the piezoelectric element and the diaphragm 176 is a vibration part that actually vibrates in the actuator 106. Moreover, it is preferable that the members included in the actuator 106 are integrally formed by firing each other. By integrally forming the actuator 106, the handling of the actuator 106 becomes easy. Furthermore, the vibration characteristics are improved by increasing the strength of the substrate 178. That is, by increasing the strength of the substrate 178, only the vibration portion of the actuator 106 vibrates, and portions other than the vibration portion of the actuator 106 do not vibrate. Further, in order not to vibrate parts other than the vibration part of the actuator 106, the strength of the substrate 178 can be increased, whereas the piezoelectric element of the actuator 106 is made thin and small and the vibration plate 176 is made thin.

  As the material of the piezoelectric layer 160, it is preferable to use lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), or lead-free piezoelectric film that does not use lead, and the substrate 178 is made of zirconia or alumina. It is preferable to use it. Further, it is preferable to use the same material as the substrate 178 for the diaphragm 176. For the upper electrode 164, the lower electrode 166, the upper electrode terminal 168, and the lower electrode terminal 170, a conductive material, for example, a metal such as gold, silver, copper, platinum, aluminum, or nickel can be used.

  The actuator 106 configured as described above can be applied to a container that contains a liquid. For example, the ink cartridge can be mounted on an ink cartridge or an ink cartridge used in an ink jet recording apparatus, or a container containing a cleaning liquid for cleaning the recording head.

  The actuator 106 shown in FIGS. 11A to 12 is mounted at a predetermined location of the liquid container so that the cavity 162 is in contact with the liquid contained in the liquid container. When the liquid is sufficiently contained in the liquid container, the inside of the cavity 162 and the outside thereof are filled with the liquid. On the other hand, when the liquid in the liquid container is consumed and the liquid level drops below the mounting position of the actuator, there is no liquid in the cavity 162, or liquid remains only in the cavity 162 and there is gas outside the cavity 162. It becomes a state to do. The actuator 106 detects at least a difference in acoustic impedance caused by the change in the state. Accordingly, the actuator 106 can detect whether the liquid is sufficiently contained in the liquid container or whether a certain amount of liquid is consumed. Furthermore, the actuator 106 can also detect the type of liquid in the liquid container.

  Here, the principle of the liquid level detection by the actuator will be described.

  In order to detect a change in the acoustic impedance of the medium, the impedance characteristic or admittance characteristic of the medium is measured. When measuring impedance characteristics or admittance characteristics, for example, a transmission circuit can be used. The transmission circuit applies a constant voltage to the medium, changes the frequency, and measures the current flowing through the medium. Alternatively, the transmission circuit supplies a constant current to the medium and measures the voltage applied to the medium at different frequencies. A change in current value or voltage value measured by the transmission circuit indicates a change in acoustic impedance. Further, a change in the frequency fm at which the current value or voltage value is maximized or minimized also indicates a change in acoustic impedance.

  Apart from the above method, the actuator can detect a change in the acoustic impedance of the liquid using a change only in the resonance frequency. When using the method of detecting the resonance frequency by measuring the counter electromotive force generated by the residual vibration remaining in the vibration part after the vibration part of the actuator vibrates as a method using the change in the acoustic impedance of the liquid, for example, A piezoelectric element can be used. The piezoelectric element is an element that generates a counter electromotive force due to residual vibration remaining in the vibration part of the actuator, and the magnitude of the counter electromotive force varies depending on the amplitude of the vibration part of the actuator. Therefore, detection is easier as the amplitude of the vibration part of the actuator is larger. In addition, the period in which the magnitude of the back electromotive force changes depends on the frequency of residual vibration in the vibration part of the actuator. Therefore, the frequency of the vibration part of the actuator corresponds to the frequency of the counter electromotive force. Here, the resonance frequency is a frequency in a resonance state between the vibration part of the actuator and the medium in contact with the vibration part.

  In order to obtain the resonance frequency fs, the waveform obtained by the back electromotive force measurement when the vibration part and the medium are in the resonance state is Fourier-transformed. The vibration of the actuator is not only deformed in one direction but is accompanied by various deformations such as deflection and extension, and therefore has various frequencies including the resonance frequency fs. Therefore, the resonance frequency fs is determined by Fourier-transforming the back electromotive force waveform when the piezoelectric element and the medium are in the resonance state and specifying the most dominant frequency component.

  The frequency fm is a frequency when the admittance of the medium is maximum or the impedance is minimum. Assuming the resonance frequency fs, the frequency fm causes a slight error with respect to the resonance frequency fs due to dielectric loss or mechanical loss of the medium. However, since it takes time to derive the resonance frequency fs from the actually measured frequency fm, the frequency fm is generally used instead of the resonance frequency. Here, by inputting the output of the actuator 106 to the transmission circuit, the actuator 106 can detect at least the acoustic impedance.

  A resonance specified by a method for measuring the frequency fm by measuring the impedance characteristic or admittance characteristic of the medium, and a method for measuring the resonance frequency fs by measuring the counter electromotive force generated by the residual vibration vibration in the vibration part of the actuator. Experiments have shown that there is little difference in frequency.

  The vibration region of the actuator 106 is a portion constituting the cavity 162 determined by the opening 161 of the vibration plate 176. When the liquid is sufficiently stored in the liquid container, the cavity 162 is filled with the liquid, and the vibration region comes into contact with the liquid in the liquid container. On the other hand, when there is not enough liquid in the liquid container, the vibration region is in contact with the liquid remaining in the cavity in the liquid container, or is not in contact with the liquid but is in contact with gas or vacuum.

  The actuator 106 of the present invention is provided with a cavity 162, whereby the liquid in the liquid container can be designed to remain in the vibration region of the actuator 106. The reason is as follows.

  Depending on the mounting position and mounting angle of the actuator on the liquid container, the liquid may adhere to the vibration area of the actuator even though the liquid level of the liquid in the liquid container is below the mounting position of the actuator. is there. When the actuator detects the presence or absence of liquid only by the presence or absence of liquid in the vibration region, the liquid attached to the vibration region of the actuator hinders accurate detection of the presence or absence of liquid.

  For example, when the liquid level is below the mounting position of the actuator, if the liquid container is swung due to the reciprocating movement of the carriage, etc. An erroneous determination is made that there is sufficient liquid in the liquid container. Therefore, conversely, even when the liquid remains there, by actively providing a cavity designed to accurately detect the presence or absence of the liquid, the liquid container oscillates and the liquid level undulates However, the malfunction of the actuator can be prevented. In this manner, malfunctions can be prevented by using an actuator having a cavity.

  Further, as shown in FIG. 12E, the case where there is no liquid in the liquid container and the liquid in the liquid container remains in the cavity 162 of the actuator 106 is set as the threshold value for the presence or absence of liquid. That is, if there is no liquid around the cavity 162 and there is less liquid in the cavity than this threshold, it is determined that there is no ink. If there is liquid around the cavity 162 and there is more liquid than this threshold, ink is present. to decide. For example, when the actuator 106 is mounted on the side wall of the liquid container, it is determined that there is no ink when the liquid in the liquid container is below the mounting position of the actuator, and the liquid in the liquid container is above the mounting position of the actuator. In some cases, it is determined that ink is present. By setting the threshold in this way, it is determined that there is no ink even when the ink in the cavity has dried and the ink has run out. Even if it adheres to the cavity, the threshold value is not exceeded, so it can be determined that there is no ink.

  Here, the operation and principle of detecting the state of the liquid in the liquid container from the resonance frequency of the medium and the vibrating portion of the actuator 106 by measuring the back electromotive force will be described with reference to FIGS. 11A to 12. In the actuator 106, a voltage is applied to the upper electrode 164 and the lower electrode 166 via the upper electrode terminal 168 and the lower electrode terminal 170, respectively. An electric field is generated in a portion of the piezoelectric layer 160 sandwiched between the upper electrode 164 and the lower electrode 166. The piezoelectric layer 160 is deformed by the electric field. When the piezoelectric layer 160 is deformed, the vibration region of the vibration plate 176 is flexibly vibrated. For a while after the piezoelectric layer 160 is deformed, the flexural vibration remains in the vibration portion of the actuator 106.

  The residual vibration is free vibration between the vibration part of the actuator 106 and the medium. Therefore, by setting the voltage applied to the piezoelectric layer 160 to a pulse waveform or a rectangular wave, it is possible to easily obtain the resonance state between the vibrating portion and the medium after the voltage is applied. The residual vibration causes the vibration portion of the actuator 106 to vibrate, so that the piezoelectric layer 160 is also deformed. Accordingly, the piezoelectric layer 160 generates a counter electromotive force. The counter electromotive force is detected through the upper electrode 164, the lower electrode 166, the upper electrode terminal 168 and the lower electrode terminal 170. Since the resonance frequency can be specified by the detected back electromotive force, the state of the liquid in the liquid container can be detected.

In general, the resonant frequency fs is
fs = 1 / (2 * π * (M * Cact) ^1/2 ) (Expression 1) Here, M is the sum of the inertance Mact and the additional inertance M ′ of the vibration part. Cact is the compliance of the vibration part.

  FIG. 11C is a cross-sectional view of the actuator 106 when no ink remains in the cavity in this embodiment. FIGS. 12A and 12B are equivalent circuits of the vibrating portion of the actuator 106 and the cavity 162 when no ink remains in the cavity.

Mact is obtained by dividing the product of the thickness of the vibration part and the density of the vibration part by the area of the vibration part. In more detail, as shown in FIG.
Mact = Mpzt + Melectrode1 + Melectrode2 + Mvib (Formula 2)
It is expressed. Here, Mpzt is obtained by dividing the product of the thickness of the piezoelectric layer 160 and the density of the piezoelectric layer 160 in the vibrating portion by the area of the piezoelectric layer 160. Melectrode1 is obtained by dividing the product of the thickness of the upper electrode 164 and the density of the upper electrode 164 in the vibrating portion by the area of the upper electrode 164. Melectrode2 is obtained by dividing the product of the thickness of the lower electrode 166 and the density of the lower electrode 166 in the vibrating portion by the area of the lower electrode 166. Mvib is obtained by dividing the product of the thickness of the diaphragm 176 and the density of the diaphragm 176 in the vibration section by the area of the vibration region of the diaphragm 176. However, in the present embodiment, Mact can be calculated from the thickness, density, and area of the entire vibration unit, and in this embodiment, each of the vibration regions of the piezoelectric layer 160, the upper electrode 164, the lower electrode 166, and the vibration plate 176 is obtained. Although the areas have the above-described magnitude relationship, the difference between the areas is preferably small. Moreover, in this embodiment, in the piezoelectric layer 160, the upper electrode 164, and the lower electrode 166, it is preferable that parts other than the circular part which is the main part are so small as to be negligible with respect to the main part.

  Accordingly, in the actuator 106, Mact is the sum of the inertances of the vibration regions of the upper electrode 164, the lower electrode 166, the piezoelectric layer 160 and the vibration plate 176. The compliance Cact is a compliance of a portion formed by the vibration region of the upper electrode 164, the lower electrode 166, the piezoelectric layer 160, and the vibration plate 176.

12A, 12B, 12D, and 12F show an equivalent circuit of the vibration part of the actuator 106 and the cavity 162. In these equivalent circuits, Cact is the vibration part of the actuator 106. Indicates compliance. Cpzt, Celectrode1, Celectrode2, and Cvib respectively indicate the compliance of the piezoelectric layer 160, the upper electrode 164, the lower electrode 166, and the diaphragm 176 in the vibration part. Cact is expressed by Equation 3 below.
1 / Cact = (1 / Cpzt) + (1 / Celectrode1) + (1 / Celectrode2) + (1 / Cvib) (Formula 3)

  From Equation 2 and Equation 3, FIG. 12A can also be expressed as FIG.

  The compliance Cact represents a volume that can receive the medium by deformation when pressure is applied to the unit area of the vibration part. The compliance Cact may be said to represent the ease of deformation.

FIG. 12C is a cross-sectional view of the actuator 106 when the liquid is sufficiently contained in the liquid container and the liquid is filled around the vibration region of the actuator 106. M′max in FIG. 12C represents the maximum value of additional inertance when the liquid is sufficiently contained in the liquid container and the liquid is filled around the vibration region of the actuator 106. M 'max is
M′max = (π * ρ / (2 * k ³ )) * (2 * (2 * k * a) ³ / (3 * π)) / (π * a ² ) ² (Formula 4) (a is (The radius of the vibration part, ρ is the density of the medium, and k is the wave number.)
It is represented by Equation 4 is established when the vibration region of the actuator 106 is a circle having a radius a. The additional inertance M ′ is an amount indicating that the mass of the vibration part is apparently increased by the action of the medium in the vicinity of the vibration part. As can be seen from Equation 4, M′max varies greatly depending on the radius a of the vibrating portion and the density ρ of the medium.

Wave number k is
k = 2 * π * fact / c (Formula 5)
(Fact is the resonance frequency of the vibrating part when the liquid is not touching. C is the speed of sound propagating through the medium.)
It is represented by

  FIG. 12D shows an equivalent circuit of the vibration part of the actuator 106 and the cavity 162 in the case of FIG. 12C in which the liquid is sufficiently contained in the liquid container and the liquid is filled around the vibration region of the actuator 106. Indicates.

FIG. 12E is a cross-sectional view of the actuator 106 when the liquid in the liquid container is consumed and there is no liquid around the vibration region of the actuator 106, but the liquid remains in the cavity 162 of the actuator 106. Show. Formula 4 is a formula representing the maximum inertance M′max determined from the density ρ of the ink, for example, when the liquid container is filled with liquid. On the other hand, when the liquid in the liquid container is consumed, and the liquid around the vibration region of the actuator 106 becomes gas or vacuum while the liquid remains in the cavity 162,
M ′ = ρ * t / S (Formula 6)
It can be expressed. t is the thickness of the medium involved in the vibration. S is the area of the vibration region of the actuator 106. When this vibration region is a circle having a radius a, S = π * a ² . Therefore, the additional inertance M ′ follows the equation 4 when the liquid is sufficiently contained in the liquid container and the liquid is filled around the vibration region of the actuator 106. On the other hand, when the liquid is consumed and the liquid around the vibration region of the actuator 106 becomes a gas or a vacuum while the liquid remains in the cavity 162, Equation 6 is satisfied.

  Here, as shown in FIG. 12E, the liquid in the liquid container is consumed and there is no liquid in the vicinity of the vibration region of the actuator 106, but the liquid remains in the cavity 162 of the actuator 106. For the sake of convenience, the inertance M ′ is referred to as M′cav, and is distinguished from the additional inertance M′max in the case where liquid is filled around the vibration region of the actuator 106.

  FIG. 12F shows the case of FIG. 12E where the liquid in the liquid container is consumed and there is no liquid around the vibration region of the actuator 106 but the liquid remains in the cavity 162 of the actuator 106. 3 shows an equivalent circuit of the vibrating portion of the actuator 106 and the cavity 162.

Here, the characteristic values related to the state of the medium are the density ρ of the medium and the thickness t of the medium in Equation 6. When the liquid is sufficiently stored in the liquid container, the liquid comes into contact with the vibrating portion of the actuator 106, and when the liquid is not sufficiently stored in the liquid container, the liquid remains in the cavity, Alternatively, gas or vacuum comes into contact with the vibrating portion of the actuator 106. When the liquid around the actuator 106 is consumed and the additional inertance in the process of shifting from M′max in FIG. 12C to M′cav in FIG. 12E is M ′ var, the liquid is contained in the liquid container. Since the thickness t of the medium changes depending on the state, the additional inertance M′var changes and the resonance frequency fs also changes. Therefore, the presence or absence of liquid in the liquid container can be detected by specifying the resonance frequency fs. Here, when t = d as shown in FIG. 12 (E), when M′cav is expressed using Equation 6, the cavity depth d is substituted for t in Equation 6,
M′cav = ρ * d / S (Formula 7)
It becomes.

  Even if the mediums are different types of liquid, the density ρ varies depending on the composition, so that the additional inertance M ′ changes and the resonance frequency fs also changes. Therefore, the type of liquid can be detected by specifying the resonance frequency fs. If only one of ink or air is in contact with the vibrating portion of the actuator 106 and they are not mixed, the difference in M ′ can be detected even by calculation using Equation 4.

  FIG. 13A is a graph illustrating the relationship between the amount of ink in the ink cartridge, the ink, and the resonance frequency fs of the vibration unit. Here, ink will be described as an example of liquid. The vertical axis represents the resonance frequency fs, and the horizontal axis represents the ink amount.

  When the ink composition is constant, the resonance frequency fs increases as the remaining ink amount decreases.

  When ink is sufficiently contained in the ink container, and the ink is filled around the vibration region of the actuator 106, the maximum added inertance M'max is a value expressed by Equation 4. On the other hand, when the ink is consumed and the liquid remains in the cavity 162, but the ink is not filled around the vibration region of the actuator 106, the additional inertance M′var is expressed by Equation 6 based on the thickness t of the medium. Is calculated by Since t in Equation 6 is the thickness of the medium involved in vibration, the ink is gradually consumed by reducing d (see FIG. 11B) of the cavity 162 of the actuator 106, that is, by making the substrate 178 sufficiently thin. It is also possible to detect the going process (see FIG. 12C). Here, tink is the thickness of ink involved in vibration, and tink-max is the tink at M'max. For example, the actuator 106 is disposed almost horizontally with respect to the ink level on the bottom surface of the ink cartridge. When the ink is consumed and the ink level reaches below the level of tink-max from the actuator 106, M'var gradually changes according to Equation 6, and the resonance frequency fs gradually changes according to Equation 1. Therefore, as long as the ink level is within the range t, the actuator 106 can gradually detect the ink consumption state.

  Further, by increasing or decreasing the vibration area of the actuator 106 and arranging it vertically, S in Equation 6 changes according to the position of the liquid level due to ink consumption. Therefore, the actuator 106 can also detect a process in which ink is gradually consumed. For example, the actuator 106 is disposed on the side wall of the ink cartridge substantially perpendicular to the ink level. When the ink is consumed and the liquid level of the ink reaches the vibration region of the actuator 106, the additional inertance M 'decreases as the liquid level decreases, so that the resonance frequency fs gradually increases according to Equation 1. Therefore, as long as the ink level is within the range of the diameter 2a of the cavity 162 (see FIG. 12C), the actuator 106 can gradually detect the ink consumption state.

  A curve X in FIG. 13A shows the amount of ink contained in the ink cartridge and the ink and the vibration portion when the cavity 162 of the actuator 106 is sufficiently shallow or when the vibration region of the actuator 106 is sufficiently large or long. The relationship with the resonance frequency fs is shown. It can be understood that the amount of ink in the ink cartridge decreases and the resonance frequency fs of the ink and the vibration part gradually changes.

More specifically, the case where the process in which ink is gradually consumed can be detected means that both liquid and gas having different densities exist in the vicinity of the vibration region of the actuator 106 and are involved in vibration. Is the case. As the ink is gradually consumed, the medium involved in the vibration around the vibration region of the actuator 106 increases the gas while decreasing the liquid. For example, when the actuator 106 is disposed horizontally with respect to the ink level and when tink is smaller than tink-max, the medium involved in the vibration of the actuator 106 includes both ink and gas. Therefore, when the area S of the vibration region of the actuator 106 is expressed as a state where M′max or less in Expression 4 is expressed by the additional mass of ink and gas,
M ′ = M′air + M′ink = ρair * tair / S + ρink * tink / S (Formula 8)
It becomes. Here, M′air is an inertance of air, and M′ink is an inertance of ink. ρair is the density of air, and ρink is the density of ink. tair is the thickness of air involved in vibration, and tink is the thickness of ink involved in vibration. Among the media involved in the vibration around the vibration region of the actuator 106, as the liquid decreases and the gas increases, the tair increases when the actuator 106 is arranged substantially horizontally with respect to the ink surface. Tink decreases. Thereby, M′var gradually decreases and the resonance frequency gradually increases. Therefore, the amount of ink remaining in the ink cartridge or the amount of ink consumed can be detected. The reason why only the liquid density is calculated in Expression 7 is that it is assumed that the air density is negligibly small relative to the liquid density.

In the case where the actuator 106 is disposed substantially perpendicular to the ink liquid level, the medium that is involved in the vibration of the actuator 106 is the ink only area and the medium that is involved in the vibration of the actuator 106 among the vibration areas of the actuator 106. It is considered as an equivalent circuit (not shown) in parallel with the gas region. If the medium related to the vibration of the actuator 106 is Sink and the area of the medium only related to the vibration of the actuator 106 is Sair, then Sair.
1 / M ′ = 1 / M′air + 1 / M′ink = Sair / (ρair * tair) + Sink / (ρink * tink) (Equation 9)
It becomes.

  Equation 9 is applied when ink is not held in the cavity of the actuator 106. The case where ink is held in the cavity of the actuator 106 can be calculated by Equation 7, Equation 8, and Equation 9.

  On the other hand, when the substrate 178 is thick, that is, when the depth d of the cavity 162 is deep and d is relatively close to the medium thickness tink-max, or when the vibration region is very small compared to the height of the liquid container In practice, rather than detecting a process in which the ink gradually decreases, it is detected that the ink level is higher than the actuator mounting position. In other words, the presence or absence of ink in the vibration region of the actuator is detected. For example, the curve Y in FIG. 13A shows the relationship between the amount of ink in the ink cartridge and the resonance frequency fs of the ink and the vibration part in the case of a small circular vibration region. A state is shown in which the ink and the resonance frequency fs of the vibrating portion change drastically between the ink amount Q before and after the ink level in the ink cartridge passes through the mounting position of the actuator. From this, it is possible to detect whether or not a predetermined amount of ink remains in the ink cartridge.

  FIG. 13B shows the relationship between the ink density and the resonance frequency fs of the ink and the vibration part in the curve Y of FIG. 13A. Ink is used as an example of the liquid.

  As shown in FIG. 13B, when the ink density is increased, the additional inertance is increased, so that the resonance frequency fs is decreased. That is, the resonance frequency fs varies depending on the type of ink. Therefore, by measuring the resonance frequency fs, it is possible to confirm whether or not inks having different densities are mixed when refilling the ink.

  That is, ink cartridges that contain different types of ink can be identified.

  Subsequently, the conditions under which the liquid state can be accurately detected when the size and shape of the cavity are set so that the liquid remains in the cavity 162 of the actuator 106 even when the liquid in the liquid container is empty. Detailed description. If the actuator 106 can detect the liquid state when the cavity 162 is filled with the liquid, the actuator 106 can detect the liquid state even when the cavity 162 is not filled with the liquid.

  The resonance frequency fs is a function of the inertance M. The inertance M is the sum of the inertance Mact and the additional inertance M ′ of the vibration part. Here, the additional inertance M ′ is related to the liquid state. The additional inertance M ′ is an amount indicating that the mass of the vibration part is apparently increased by the action of the medium in the vicinity of the vibration part. That is, it means an increase in mass of the vibrating part due to apparent absorption of the medium by the vibration of the vibrating part.

  Therefore, when M ′ cav is larger than M ′ max in Equation 4, all of the apparently absorbing medium is the liquid remaining in the cavity 162. Therefore, it is the same as the state where the liquid container is filled with the liquid. In this case, since M 'does not change, the resonance frequency fs also does not change. Therefore, the actuator 106 cannot detect the state of the liquid in the liquid container.

  On the other hand, when M ′ cav is smaller than M ′ max in Equation 4, the apparently absorbing medium is the liquid remaining in the cavity 162 and the gas or vacuum in the liquid container. At this time, unlike the state where the liquid container is filled with the liquid, M ′ changes, so the resonance frequency fs changes. Therefore, the actuator 106 can detect the state of the liquid in the liquid container.

  That is, when the liquid in the liquid container is empty and the liquid remains in the cavity 162 of the actuator 106, the condition under which the actuator 106 can accurately detect the liquid state is that M′cav is higher than M′max. It is small. The condition M′max> M′cav that allows the actuator 106 to accurately detect the liquid state is not related to the shape of the cavity 162.

Here, M′cav is the mass of the liquid having a volume approximately equal to the volume of the cavity 162. Therefore, from the inequality M′max> M′cav, the condition under which the actuator 106 can accurately detect the liquid state can be expressed as the condition of the capacity of the cavity 162. For example, when the radius of the opening 161 of the circular cavity 162 is a and the depth of the cavity 162 is d,
M′max> ρ * d / πa ² (Formula 10)
It is. When Expression 10 is expanded, a / d> 3 * π / 8 (Expression 11)
This condition is required. Expressions 10 and 11 are valid only when the shape of the cavity 162 is circular. Using the formula of M′max in the case of non-circularity and calculating by replacing πa ^{2 in} formula 10 with its area, the relationship between the dimensions such as the width and length of the cavity and the depth can be derived.

  Therefore, if the actuator 106 has the cavity 162 having the radius a of the opening 161 and the depth d of the cavity 162 satisfying Expression 11, the liquid in the liquid container is empty and the liquid is contained in the cavity 162. Even if it remains, the liquid state can be detected without malfunction.

  Since the additional inertance M 'also affects the acoustic impedance characteristics, it can be said that the method of measuring the counter electromotive force generated in the actuator 106 due to residual vibration detects at least a change in acoustic impedance.

  Further, according to the present embodiment, the back electromotive force generated in the actuator 106 due to the subsequent residual vibration after the actuator 106 generates vibration is measured. However, it is not always necessary for the vibrating portion of the actuator 106 to vibrate the liquid by its own vibration caused by the drive voltage. That is, even if the vibration part does not oscillate by itself, the piezoelectric layer 160 is bent and deformed by vibrating with a certain range of liquid in contact therewith. This residual vibration generates a counter electromotive force voltage in the piezoelectric layer 160 and transmits the counter electromotive force voltage to the upper electrode 164 and the lower electrode 166. The state of the medium may be detected by using this phenomenon. For example, in an ink jet recording apparatus, even if an ink cartridge or its internal ink state is detected by using vibration around a vibration portion of an actuator generated by vibration due to reciprocation of a carriage by scanning of a recording head during printing Good.

  14A and 14B show the residual vibration waveform of the actuator 106 and the method for measuring the residual vibration after the actuator 106 is vibrated. The upper and lower levels of the ink level at the mounting position level of the actuator 106 in the ink cartridge can be detected by a change in the frequency or amplitude of the residual vibration after the actuator 106 oscillates. 14A and 14B, the vertical axis indicates the voltage of the counter electromotive force generated by the residual vibration of the actuator 106, and the horizontal axis indicates time. The residual vibration of the actuator 106 generates a voltage analog signal waveform as shown in FIGS. 14A and 14B. Next, the analog signal is converted into a digital numerical value corresponding to the frequency of the signal.

  In the example shown in FIGS. 14A and 14B, the presence or absence of ink is detected by measuring the time during which four pulses from the fourth pulse to the eighth pulse of the analog signal occur.

  More specifically, after the actuator 106 oscillates, the number of times that a predetermined reference voltage set in advance is crossed from the low voltage side to the high voltage side is counted. The digital signal is set to High between 4 counts and 8 counts, and the time from 4 counts to 8 counts is measured by a predetermined clock pulse.

  FIG. 14A shows a waveform when the ink liquid level is higher than the mounting position level of the actuator 106. On the other hand, FIG. 14B shows a waveform when there is no ink at the mounting position level of the actuator 106. Comparing FIG. 14A and FIG. 14B, it can be seen that FIG. 14A has a longer time from 4 to 8 counts than FIG. 14B. In other words, the time from 4 counts to 8 counts varies depending on the presence or absence of ink. By using this time difference, it is possible to detect the ink consumption state. The reason for counting from the fourth count of the analog waveform is to start measurement after the vibration of the actuator 106 is stabilized. The count from the fourth count is merely an example, and the count may be counted from an arbitrary count. Here, signals from the 4th count to the 8th count are detected, and the time from the 4th count to the 8th count is measured by a predetermined clock pulse. Thereby, the resonance frequency is obtained. The clock pulse is preferably a clock pulse equal to a clock for controlling a semiconductor memory device or the like attached to the ink cartridge. Note that it is not necessary to measure the time up to the 8th count, and it may be counted up to an arbitrary count. In FIGS. 14A and 14B, the time from the 4th count to the 8th count is measured, but the times within different count intervals may be detected according to the circuit configuration for detecting the frequency.

  For example, when the ink quality is stable and the fluctuation of the peak amplitude is small, the resonance frequency may be obtained by detecting the time from the 4th count to the 6th count in order to increase the detection speed. . When the ink quality is unstable and the fluctuation of the pulse amplitude is large, the time from the 4th count to the 12th count may be detected in order to accurately detect the residual vibration.

  In another embodiment, the number of back electromotive force voltage waveforms within a predetermined period may be counted (not shown). The resonance frequency can also be obtained by this method.

  More specifically, after the actuator 106 oscillates, the digital signal is set to High for a predetermined period, and the number of times the predetermined reference voltage is crossed from the low voltage side to the high voltage side is counted. The presence or absence of ink can be detected by measuring the count number.

  Further, as can be seen by comparing FIG. 14A and FIG. 14B, the amplitude of the back electromotive force waveform is different between when the ink is filled in the ink cartridge and when the ink is not in the ink cartridge. Therefore, the ink consumption state in the ink cartridge may be detected by measuring the amplitude of the counter electromotive force waveform without obtaining the resonance frequency. More specifically, for example, a reference voltage is set between the peak of the counter electromotive force waveform in FIG. 14A and the peak of the counter electromotive force waveform in FIG. 14B. After the actuator 106 oscillates, the digital signal is set to High at a predetermined time, and if the back electromotive force waveform crosses the reference voltage, it is determined that there is no ink. If the back electromotive force waveform does not cross the reference voltage, it is determined that ink is present.

  FIG. 15 is a perspective view showing a configuration in which the actuator 106 is integrally formed as the mounting module body 100. The module body 100 is attached to a predetermined portion of the container main body 1 of the ink cartridge. The module body 100 is configured to detect the consumption state of the liquid in the container body 1 by detecting at least a change in acoustic impedance in the ink liquid. The module body 100 of the present embodiment has a liquid container mounting portion 101 for mounting the actuator 106 to the container body 1. The liquid container mounting portion 101 has a structure in which a cylindrical portion 116 that houses an actuator 106 that oscillates in response to a drive signal is placed on a base 102 having a substantially rectangular plane. The module body 100 is mounted on the inner wall of the ink cartridge container. Lead wires 104a and 104b are connected to electrode terminals of the actuator 106 and extend to the outside through the side wall of the ink cartridge. Thereby, the electric signal detected by the actuator 106 can be conducted to the outside of the ink cartridge.

  FIG. 16 is a perspective view showing another embodiment of the module body. In the module body 400 of this embodiment, a piezoelectric device mounting portion 405 is formed in the liquid container mounting portion 401. In the liquid container mounting portion 401, a cylindrical column portion 403 is formed on a base 402 having a square plane. Further, the piezoelectric device mounting portion 405 includes a plate-like element 406 and a concave portion 413 that stand on the cylindrical portion 403. The actuator 106 is disposed in the recess 413 provided on the side surface of the plate-like element 406.

  17A, 17B, and 17C show still another embodiment of the module body. Similar to the module body 100 shown in FIG. 15, the module body 500 of FIGS. 17, 17 </ b> B, and 17 </ b> C includes a liquid container mounting portion 501 having a base 502 and a cylindrical portion 503. The module body 500 further includes lead wires 504a and 504b, an actuator 106, a film 508, and a plate 510. The base 502 included in the liquid container mounting portion 501 has an opening 514 at the center so as to accommodate the lead wires 504a and 504b, and a recess 513 so as to accommodate the actuator 106, the film 508, and the plate 510. Is done. The actuator 106 is fixed to the piezoelectric device mounting portion 505 via the plate 510. Accordingly, the lead wires 504a and 504b, the actuator 106, the film 508, and the plate 510 are integrally attached to the liquid container attachment portion 501. The module body 500 according to the present embodiment includes a base 502 on which a cylindrical base whose upper surface is slanted in the vertical direction is placed on a base whose plane is a square. A cylindrical portion 503 whose upper surface of the base 502 is inclined in the vertical direction is formed. The actuator 106 is disposed on a recess 513 provided obliquely in the vertical direction on the upper surface of the cylindrical portion 503.

  The tip of the module body 500 is inclined, and the actuator 106 is mounted on the inclined surface. Therefore, when the module body 500 is mounted on the bottom or side of the container body 1, the actuator 106 is inclined with respect to the vertical direction of the container body 1. The inclination angle of the tip of the module body 500 is preferably between approximately 30 ° and 60 ° in view of detection performance.

  The module body 500 is attached to the bottom wall, the side wall, or the top wall in the container body 1 so that the actuator 106 is disposed in the container body 1. When the module body 500 is attached to the side wall of the container body 1, the actuator 106 is attached to the container body 1 so as to face the upper side, the lower side, or the lateral side of the container body 1 while being inclined. On the other hand, when the module body 500 is mounted on the bottom surface 1a of the container main body 1, the actuator 106 is preferably attached to the container main body 1 so as to face the ink supply port side of the container main body 1 while being inclined. .

  FIG. 18 illustrates an embodiment comprising a mold structure 600 that includes an actuator 106. In this embodiment, the mold structure 600 is used as one of the attachment structures. The mold structure 600 includes an actuator 106 and a mold part 364. The actuator 106 and the mold part 364 are integrally formed. The mold part 364 is formed of a plastic material such as silicon resin. The mold part 364 has a lead wire 362 inside. Mold portion 364 is formed to have two legs extending from actuator 106. In order to fix the mold part 364 and the container body 1 in a liquid-tight manner, the mold part 364 is formed with hemispherical ends of two legs of the mold part 364. The mold part 364 is attached to the container body 1 so that the actuator 106 protrudes into the container body 1, and the vibration part of the actuator 106 comes into contact with the ink in the container body 1. The mold part 364 protects the upper electrode 164, the piezoelectric layer 160, and the lower electrode 166 of the actuator 106 from ink.

  18 eliminates the need for a sealing structure 372 between the mold portion 364 and the container body 1, so that ink is unlikely to leak from the container body 1. Further, since the mold structure 600 does not protrude from the outside of the container body 1, the actuator 106 can be protected from contact with the outside. When the ink cartridge shakes, the ink adheres to the upper surface of the container main body 1, and the ink dripping from the upper surface of the container main body 1 contacts the actuator 106, so that the actuator 106 may malfunction. In the mold structure 600, since the mold part 364 protects the actuator 106, the actuator 106 does not malfunction due to the ink dripping from the upper surface of the container body 1.

  In the present embodiment, the mold structure 600 is attached to the top wall 1040 located above the ink level in the container main body 1. The vibration region of the actuator 106 is slightly below the liquid level when the liquid is not consumed. Therefore, shortly after the ink cartridge is used and the ink starts to be consumed, the vibration region of the actuator 106 detects gas. Therefore, it is not always necessary to mount the actuator 106 on the side wall of the container body 1.

  Note that by forming the mold structure 600 so that the vibration region of the actuator 106 is positioned slightly above the ink level, the same effect as that of the ink cartridge according to the embodiment of FIG. 2 can be obtained. .

  FIG. 19A is an enlarged cross-sectional view of a circuit board 610 provided in the ink cartridge, and FIG. 19B is a perspective view from the front thereof. In the circuit board 610 according to the present embodiment, the semiconductor memory means 7 and the actuator 106 are integrally formed. The circuit board 610 can be provided in an ink cartridge instead of the actuator 106 in the embodiment of FIGS. 19A and 19B, the semiconductor memory means 7 is formed above the circuit board 610, and the actuator 106 is formed below the semiconductor memory means 7 on the same circuit board 610. The circuit board 610 has a plurality of crimping portions 616 for attaching the circuit board 610 to the ink cartridge. The circuit board 610 is fixed to the ink cartridge by the crimping portion 616. The external terminal 612 of the semiconductor storage means 7 and the external terminal 107 of the actuator 106 are formed so as to be in electrical contact with the outside through the side wall of the ink cartridge. When the external terminal 612 and the external terminal 107 are electrically connected to the outside, the semiconductor memory means 7 can exchange electrical signals with the outside.

  The semiconductor memory means 7 may be constituted by a rewritable semiconductor memory such as an EEPROM. Since the semiconductor storage means 7 and the actuator 106 are formed on the same circuit board 610, a single attachment process is sufficient when the actuator 106 and the semiconductor storage means 7 are attached to the ink cartridge. Further, the work process at the time of manufacturing and recycling the ink cartridge is simplified. Furthermore, since the number of parts is reduced, the manufacturing cost of the ink cartridge is reduced.

  The actuator 106 detects the ink consumption state in the ink cartridge. The semiconductor storage unit 7 stores information such as the remaining ink amount detected by the actuator 106, the characteristic value detected by the characteristic value detection unit 810, and the determination result of the characteristic value determination unit 820, and can function as the storage unit 850. . Preferably, the semiconductor memory means 7 stores predetermined conditions that should be satisfied by the characteristic value of the actuator 106, past errors, and commands. Further, the resonance frequency when the ink is full or end is stored in the semiconductor memory unit 7 in advance, and the variation in detecting the ink remaining amount is corrected by reading the resonance frequency data on the ink jet recording apparatus side. Good.

  FIG. 20 shows an embodiment of an ink cartridge and an ink jet recording apparatus using the actuator 106 shown in FIGS. 11A, 11B, and 11C. The plurality of ink cartridges 180 are attached to an ink jet recording apparatus having a plurality of ink introduction portions 182 and holders 184 corresponding to the respective ink cartridges 180. The plurality of ink cartridges 180 accommodate different types of ink, for example, colors. On the bottom surface of each of the plurality of ink cartridges 180, an actuator 106 that is a means for detecting at least acoustic impedance is mounted. By mounting the actuator 106 on the ink cartridge 180, the remaining amount of ink in the ink cartridge 180 can be detected.

  FIG. 21 shows details of the vicinity of the head portion of the ink jet recording apparatus. The ink jet recording apparatus includes an ink introducing portion 182, a holder 184, a head plate 186, and a nozzle plate 188. A plurality of nozzles 190 for ejecting ink are formed on the nozzle plate 188. The ink introduction part 182 has an air supply port 181 and an ink introduction port 183. The air supply port 181 supplies air to the ink cartridge 180. The ink introduction port 183 introduces ink from the ink cartridge 180. The ink cartridge 180 has an air introduction port 185 and an ink supply port 187. The air introduction port 185 introduces air from the air supply port 181 of the ink introduction unit 182. The ink supply port 187 supplies ink to the ink introduction port 183 of the ink introduction unit 182. When the ink cartridge 180 introduces air from the ink introduction part 182, the supply of ink from the ink cartridge 180 to the ink introduction part 182 is promoted. The holder 184 communicates the ink supplied from the ink cartridge 180 via the ink introduction part 182 to the head plate 186.

  Ink is supplied from the ink cartridge 180 to the head via the ink introducing portion 182 and is ejected from the nozzle to the recording medium. Thereby, the ink jet recording apparatus prints on the recording medium. In FIGS. 20 and 21, the actuator 106 is omitted.

  As described above, the ink cartridge mounted on the carriage is separated from the carriage, and the ink cartridge or the actuator 106 is mounted on the carriage. However, the ink is integrated with the carriage and mounted on the inkjet recording apparatus together with the carriage. The actuator 106 may be attached to the cartridge. Furthermore, the actuator 106 may be mounted on an off-carriage ink cartridge that supplies ink to the carriage via a tube or the like that is separate from the carriage. Furthermore, the actuator of the present invention may be mounted on an ink cartridge that is configured to be replaceable integrally with the recording head.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  According to the present invention, it is possible to determine whether the piezoelectric device operates normally, and it is possible to control the ink jet recording apparatus based on the determination of the quality of the piezoelectric device.

  In addition, according to the present invention, it is possible to confirm that a predetermined amount of liquid is contained in the liquid container at the time of manufacturing the liquid container or after manufacturing.

  Furthermore, according to the present invention, it is possible to detect when a predetermined amount of ink does not actually enter the liquid container due to a defect in the liquid container or the piezoelectric device. The ink jet recording apparatus can be controlled based on the detection result.

  Furthermore, according to the present invention, the inclination of the liquid container can be detected, for example, when the liquid container is not correctly attached, and the inkjet recording apparatus is controlled based on the detection result of the inkjet recording apparatus and the ink amount. Can do.

It is a figure which shows the ink cartridge for single colors, for example, black ink, as one Embodiment of the liquid container by the reference example of this invention. It is a figure which shows the ink cartridge as other embodiment of the liquid container by the reference example of this invention. It is a figure which shows the ink cartridge as other embodiment of the liquid container by this invention. It is a figure which shows the ink cartridge as other embodiment of the liquid container by the reference example of this invention. It is a figure which shows sectional drawing of the transversal direction of the ink cartridge as other embodiment of the liquid container by the reference example of this invention. It is a figure which shows the ink cartridge as other embodiment of the liquid container by the reference example of this invention. It is the perspective view seen from the back side which shows the ink cartridge which accommodates multiple types of ink as other embodiment of the liquid container by this invention. It is sectional drawing which shows the principal part of the inkjet recording device using the ink cartridge shown in FIG. 1 as one Embodiment of the inkjet recording device by this invention. 1 is a block diagram illustrating a control device of an ink jet recording apparatus as one embodiment of the present invention. FIG. 2 is a flowchart illustrating a control method of the ink jet recording apparatus in which the ink cartridge illustrated in FIG. 1 is mounted. 2 is a flowchart illustrating a control method of the ink jet recording apparatus in which the ink cartridge illustrated in FIG. 1 is mounted. It is a figure which shows the detail of the actuator which is an example of the piezoelectric device used in this invention. It is a figure which shows the detail of the actuator which is an example of the piezoelectric device used in this invention. It is a figure which shows the detail of the actuator which is an example of the piezoelectric device used in this invention. FIG. 12 is a diagram showing details and an equivalent circuit of the actuator shown in FIG. 11. FIG. 6 is a graph showing a relationship between the amount of ink in an ink cartridge and the resonance frequency of ink and a vibration part. FIG. 6 is a graph showing a relationship between the amount of ink in an ink cartridge and the resonance frequency of ink and a vibration part. It is a figure which shows the waveform of the residual vibration of an actuator after vibrating an actuator, and the measuring method of residual vibration. It is a figure which shows the waveform of the residual vibration of an actuator after vibrating an actuator, and the measuring method of residual vibration. FIG. 12 is a perspective view showing a configuration in which the actuator shown in FIG. 11 is integrally formed as a module body. It is a perspective view which shows the other example of a module body. It is a figure which shows the further another example of a module body. It is a figure which shows the further another example of a module body. It is a figure which shows the further another example of a module body. It is a figure which shows an example of the mold structure provided with the actuator. It is a figure which shows the circuit board arrange | positioned at the ink cartridge as one Embodiment of the liquid container by this invention. It is a figure which shows the circuit board arrange | positioned at the ink cartridge as one Embodiment of the liquid container by this invention. FIG. 12 is a diagram illustrating an ink cartridge and an ink jet recording apparatus using the actuator shown in FIGS. 11A, 11B, and 11C as an embodiment of the present invention. FIG. 2 is a diagram showing details of the vicinity of a head portion of an ink jet recording apparatus as an embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container body 31 of ink cartridge Recording head 106, 106a, 106b Actuator (piezoelectric device)
180 Ink cartridge 720 Piezoelectric device control means 750 Control unit 810 Characteristic value detection unit 820 Characteristic value determination unit

Claims (2)

A container main body for storing a liquid to be supplied to a recording head for discharging ink droplets from a nozzle opening; and a piezoelectric device for detecting the liquid in the container main body. The liquid consumption state of the liquid container mounted on the ink jet recording apparatus In the method of detecting,
A detecting step provided inside or outside the ink jet recording apparatus for detecting vibration characteristic values of the two piezoelectric devices provided in the liquid container;
Or the evaluation unit which is provided inside or outside of the ink jet recording apparatus, the relationship between two of said piezoelectric device mutual oscillation characteristic values to each other by comparing the two oscillation characteristic value of satisfies the predetermined relative condition A determination step of determining a consumption state of the liquid in the liquid container based on whether or not;
I have a,
The predetermined relative condition is that vibration characteristic values of the two piezoelectric devices are equal;
The two piezoelectric devices are respectively disposed slightly below the liquid level in the unused liquid container and near the bottom surface of the container body.
The liquid consumption state detection method characterized by the above-mentioned. In an ink jet recording apparatus in which a liquid container having a container main body for storing liquid and a piezoelectric device for detecting the liquid in the container main body can be attached and detached,
A recording head that receives a supply of liquid from the liquid container and discharges ink droplets from a nozzle opening;
A control device for controlling the operating state of the ink jet recording apparatus,
The controller is
A detection unit for detecting vibration characteristic values of the two piezoelectric devices provided in the liquid container;
Determining the consumption condition of a liquid in said liquid container based on whether the relationship between two of said piezoelectric device mutual oscillation characteristic value each other by comparing the two oscillation characteristic value of satisfies the predetermined relative condition a determination unit that, the possess,
The predetermined relative condition is that vibration characteristic values of the two piezoelectric devices are equal;
The two piezoelectric devices are respectively disposed slightly below the liquid level in the unused liquid container and near the bottom surface of the container body.
An ink jet recording apparatus.

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