JP2023072421A - Liquid discharge device - Google Patents

Abstract

Kind Code: A1 A liquid ejecting apparatus capable of calculating a capacitance with high accuracy is provided. A liquid ejection device according to an embodiment of the present disclosure includes a first actuator including a first piezoelectric body that is deformed to eject liquid from a first nozzle; electrically connected to the first actuator; a sensor for detecting the state of the first actuator; a first sensor switch and a second sensor switch electrically connected in parallel between the first actuator and the sensor; and a controller for executing arithmetic processing for calculating the capacitance value of the piezoelectric body. [Selection drawing] Fig. 4

Description

The present technology relates to a liquid ejection device.

2. Description of the Related Art Conventionally, an inkjet printer has been proposed that estimates the temperature around a print head by measuring the capacitance of a piezoelectric element that the print head has (for example, Japanese Patent Application Laid-Open No. 2002-200011).

JP-A-11-99648

The inkjet printer described in Patent Document 1 switches between a drive state and a capacitance measurement state by switching a switch when applying a voltage to a piezoelectric element (actuator) and when measuring the capacitance of the piezoelectric element. However, there is a problem that the resistance component included in the switch lowers the measurement accuracy of the capacitance.

The present disclosure has been made in view of such circumstances, and an object of the present disclosure is to provide a liquid ejection device that reduces the resistance component and appropriately calculates the capacitance.

A liquid ejecting apparatus according to an embodiment of the present disclosure includes a first actuator including a first piezoelectric body deformed to eject liquid from a first nozzle; electrically connected to the first actuator; a first sensor switch and a second sensor switch electrically connected in parallel between the first actuator and the sensor; and the first piezoelectric body based on the detection result of the sensor. and a controller that executes arithmetic processing for calculating the capacitance value.

In the liquid ejection device according to an embodiment of the present disclosure, a plurality of switches are connected in parallel between the actuator and the control device that calculates the capacitance, thereby reducing the resistance component and achieving high accuracy. Capacitance can be calculated.

1 is a plan view schematically showing a printing device; FIG. FIG. 4 is an explanatory diagram for explaining the flow of ink between a sub-tank and an inkjet head; 2 is a schematic partial enlarged cross-sectional view of an inkjet head; FIG. 1 is a block diagram of a printing device; FIG. FIG. 10 is a diagram illustrating a difference in resonance waves between an actuator and a sensor circuit depending on the number of sensor switches to be turned on; FIG. 4 is an explanatory diagram showing an example of a temperature conversion table; FIG. 10 is a flowchart for explaining processing of the control device during temperature estimation processing; FIG. FIG. 10 is a diagram for explaining the difference in the charging time of the actuator due to the difference in electrostatic capacitance of the piezoelectric body; FIG. 10 is a diagram illustrating a difference in charging time of an actuator depending on the number of sensor switches to be turned on; 10 is a flowchart for explaining processing of the control device during temperature estimation processing according to the second embodiment; 10 is a block diagram of a printing apparatus according to Embodiment 3; FIG. 14 is a block diagram of a printing apparatus according to Embodiment 4; FIG.

(Embodiment 1)
The present invention will be described below with reference to the drawings showing a printing apparatus according to Embodiment 1. FIG. Further, the printing apparatus 1 will be described below as an example of the liquid ejecting apparatus. FIG. 1 is a plan view schematically showing a printing apparatus, and FIG. 2 is an explanatory diagram explaining the flow of ink between a sub-tank and an inkjet head. In the following description, front, back, left, and right shown in FIG. 1 are used. The front-rear direction corresponds to the conveying direction, and the left-right direction corresponds to the scanning direction. The front side of FIG. 1 corresponds to the upper side, the back side corresponds to the lower side, and the upper and lower sides are also used.

As shown in FIG. 1, the printing apparatus 1 includes a platen 2, an ink ejection device 3, transport rollers 4 and 5, and the like. A recording sheet 200 as a recording medium is placed on the upper surface of the platen 2 . The ink ejection device 3 ejects ink onto the recording paper 200 placed on the platen 2 to record an image. The ink ejection device 3 includes a carriage 6, a sub-tank 7, five inkjet heads 8, a circulation pump 10, and the like.

Two guide rails 11 and 12 that guide the carriage 6 are provided above the platen 2 and extend to the left and right. The carriage 6 is connected to an endless belt 13 extending in the left and right direction. The endless belt 13 is driven by a carriage drive motor 14 . Driven by the endless belt 13 , the carriage 6 is guided by the guide rails 11 and 12 and reciprocates in the scanning direction in the region facing the platen 2 . More specifically, the carriage 6 supports five inkjet heads 8, and performs a first movement that moves the heads from one position to another from left to right in the scanning direction; and a second movement that moves the head from another position to a position in the direction from right to left.

A cap 20 and a flushing receiver 21 are provided between the guide rails 11 and 12 . The cap 20 and the flushing receiver 21 are arranged below the ink ejection device 3 . The cap 20 is arranged at the right end of the guide rails 11 and 12, and the flushing receiver 21 is arranged at the left end of the guide rails 11 and 12. As shown in FIG. Note that the cap 20 and the flushing receiver 21 may be arranged in the opposite direction.

A sub-tank 7 and five inkjet heads 8 are mounted on a carriage 6 and reciprocate together with the carriage 6 in the scanning direction. The sub-tank 7 is connected to the cartridge holder 15 via a tube 17 . Ink cartridges 16 of one or a plurality of colors (five colors in this embodiment) are mounted in the cartridge holder 15 . Five colors include, for example, white, black, yellow, cyan and magenta.

Five ink chambers 19 are formed inside the sub-tank 7 . Five color inks supplied from five ink cartridges 16 are stored in the five ink chambers 19 respectively.

Five inkjet heads 8 are arranged in the scanning direction below the sub-tank 7 . A plurality of nozzles 80 (see FIG. 3) are formed on the lower surface of each inkjet head 8 . As shown in FIG. 2, one inkjet head 8 corresponds to one color of ink and is connected to one ink chamber 19 . That is, the five inkjet heads 8 correspond to five colors of ink, respectively, and are connected to the five ink chambers 19, respectively.

The upper surface of the inkjet head 8 is provided with an ink supply port 8a and an ink discharge port 8b. The ink supply port 8a and the ink discharge port 8b are connected to the ink chamber 19 via a tube or the like. A circulation pump 10 is interposed between the ink supply port 8 a and the ink chamber 19 .

The circulation pump 10 is, for example, a tube pump that pushes out the liquid in the tube by squeezing the tube with a rotor. The circulation pump 10 sends the ink in the ink chamber 19 to the inkjet head 8 .

Ink sent from the ink chamber 19 by the circulation pump 10 flows into the inkjet head 8 through the ink supply port 8 a and is ejected from the nozzles 80 . Ink not ejected from the nozzle 80 returns to the ink chamber 19 through the ink outlet 8b. Ink circulates between the ink chamber 19 and the inkjet head 8 . Instead of the circulation pump 10, another power source for circulation, for example, a device that feeds compressed air into the sub-tank 7 and ink to the ink jet head 8 may be used. The five inkjet heads 8 eject five color inks supplied from the sub-tanks 7 onto the recording paper 200 while moving in the scanning direction together with the carriage.

As shown in FIG. 1 , the transport roller 4 is arranged on the upstream side (rear side) of the platen 2 in the transport direction. The transport roller 5 is arranged on the downstream side (front side) of the platen 2 in the transport direction. The two transport rollers 4 and 5 are synchronously driven by a motor (not shown). Two transport rollers 4 and 5 transport the recording paper 200 placed on the platen 2 in a transport direction perpendicular to the scanning direction. The printing device 1 has a control device 50 . The control device 50 is a controller that includes a CPU or a logic circuit (for example, FPGA), a storage unit 55 such as a nonvolatile memory and a RAM, and the like, and controls a drive circuit 51, a sensor circuit 52, a switch control circuit 53, and the like, which will be described later. The control device 50 receives a print job from the external device 100 and stores it in the storage unit 55 . The control device 50 controls driving of the ink ejection device 3, the transport roller 4, and the like based on the print job, and executes print processing.
The storage unit 55 also stores the manufacturing date (manufacturing date) of the printer 1, a first temperature conversion table 551, and a second temperature conversion table 552, which will be described later. In addition, the storage unit 55 stores the point in time, the time, the number of times, and the like when the control device 50 performs various processes described later.

FIG. 3 is a schematic partial enlarged sectional view of the inkjet head 8. As shown in FIG. The inkjet head 8 has a plurality of pressure chambers 81 . A plurality of pressure chambers 81 constitute a plurality of pressure chamber rows. A diaphragm 82 is formed above the pressure chamber 81 . A layered piezoelectric body 83 is formed on the upper side of the diaphragm 82 . A first common electrode 84 is formed above each pressure chamber 81 and between the piezoelectric body 83 and the vibration plate 82 .

A second common electrode 86 is provided inside the piezoelectric body 83 . The second common electrode 86 is arranged above each pressure chamber 81 and above the first common electrode 84 . The second common electrode 86 is arranged at a position not facing the first common electrode 84 . An individual electrode 85 is formed on the upper surface of the piezoelectric body 83 above each pressure chamber 81 . The individual electrode 85 , the first common electrode 84 and the second common electrode 86 face each other vertically with the piezoelectric body 83 interposed therebetween. That is, the inkjet head 8 includes a piezoelectric body 83 , individual electrodes 85 , a first common electrode 84 and a second common electrode 86 . The vibration plate 82 , the piezoelectric body 83 , the first common electrode 84 , the individual electrodes 85 and the second common electrode 86 constitute an actuator 88 .

A nozzle plate 87 is provided below each pressure chamber 81 . The nozzle plate 87 is formed with a plurality of nozzles 80 penetrating vertically. Each nozzle 80 is arranged below each pressure chamber 81 . A plurality of nozzles 80 form a plurality of nozzle rows extending along the pressure chamber rows.

The plurality of nozzles 80 includes a first nozzle 80(1) and a second nozzle 80(2). The portion of the piezoelectric body 83 arranged above the first nozzle 80a is also called a first piezoelectric body 83(1), and the individual electrode 85 arranged above the first nozzle 80(1) is called the first individual electrode 85 ( 1). A portion of the piezoelectric body 83 arranged above the second nozzle 80(2) is also referred to as a second piezoelectric body 83(2), and an individual electrode 85 arranged above the second nozzle 80(2) is referred to as a second individual electrode 83(2). Also referred to as electrode 85(2).

As shown in FIG. 4, the first common electrode 84 is connected to the COM terminal, which in this embodiment is ground, and the second common electrode 86 is connected to the VCOM terminal. VCOM voltage is higher than COM voltage. The individual electrodes 85 are connected to the switch control circuit 53 . By applying a high or low voltage to the individual electrode 85, the piezoelectric body 83 is deformed and the diaphragm 82 vibrates. Ink is ejected from the pressure chamber 81 through the nozzle 80 by the vibration of the vibration plate 82 .

FIG. 4 is a block diagram of the printing device 1. As shown in FIG. The printer 1 includes a control device 50 , a drive circuit 51 , a sensor circuit 52 , a switch control circuit 53 and a switch section 54 . The switch section 54 includes drive switches 541(n), sensor switches 542(2n−1), and sensor switches 542(2n) (n=1, 2, 3, . . . ). Actuator 88(n) is electrically connected to drive circuit 51 via drive switch 541(n). Actuator 88(n) is also connected to sensor circuit 52 via sensor switch 542(2n−1) and sensor switch 542(2n). That is, two sensor switches 542 are electrically connected in parallel between the actuator 88(n) and the sensor circuit 52. FIG. The number of sensor switches 542 connected in parallel between the actuator 88(n) and the sensor circuit 52 is not limited to two, and may be three or more.
The switch control circuit 53 acquires an instruction signal from the control device 50 and controls on/off of each drive switch 541 and sensor switch 542 provided in the switch section 54 . Each drive switch 541 and sensor switch 542 connects the circuit when turned on, and disconnects the circuit when turned off.

The sensor circuit 52 is a sensor that detects the state of the actuator 88 . In the first embodiment, the state of actuator 88 is the resonance frequency of actuator 88 and sensor circuit 52 . The sensor circuit 52 detects, samples, quantizes, and encodes the resonance frequency with the actuator 88 and outputs the encoded digital value to the controller 50 .

The drive circuit 51 acquires an instruction signal from the control device 50 and drives the actuator 88 . Each actuator 88(n) is driven when the drive switch 541(n) between it and the drive circuit 51 is turned on.

The control device 50 executes arithmetic processing for calculating the capacitance of the piezoelectric body 83 based on the resonance frequency acquired from the sensor circuit 52, and estimates the temperature of the actuator 88 based on the capacitance of the piezoelectric body 83. Run the estimation process.

A case of driving the actuator 88 will be described. The actuator 88(n) is hereinafter referred to as the n-th actuator 88(n). For example, actuator 88(1) is the first actuator 88(1) and actuator 88(2) is the second actuator 88(2). The n-th actuator 88(n) has an n-th piezoelectric body 83(n) and causes the n-th nozzle 80(n) to eject ink.
When the first actuator 88(1) is to be driven, the control device 50 sends an instruction signal to the switch control circuit 53 to cause the switch control circuit to turn on the drive switch 541(1). Similarly, when the controller 50 drives the n-th actuator 88(n), it causes the switch control circuit to turn on the drive switch 541(n). Note that the control device 50 may drive a plurality of actuators 88 in some cases. At this time, the controller 50 turns on the plurality of drive switches 541 to drive the desired actuators 88 .

A case of calculating the capacitance of the piezoelectric body 83 included in the actuator 88 will be described. When the control device 50 calculates the capacitance of the first piezoelectric body 83(1) provided in the first actuator 88(1), the control device 50 transmits an instruction signal to the switch control circuit 53, and the sensor switch 542(1) (second At least one of the first sensor switch) and the sensor switch 542(2) (second sensor switch) is turned on. At this time, the drive switch 541(1) and the sensor switches 542 other than the sensor switches 542(1) and 542(2) are turned off.

When at least one of sensor switch 542(1) and sensor switch 542(2) is turned on, sensor circuit 52 detects the resonance frequency with first actuator 88(1) as described above, and controls the controller. Output to 50. Similarly, when calculating the capacitance of the n-th piezoelectric body 83(n), the controller 50 turns on at least one of the sensor switch 542(2n-1) and the sensor switch 542(2n) to turn on the sensor circuit. 52 to detect the resonance frequency with the nth actuator 88(n). The control device 50 acquires the resonance frequency detected by the sensor circuit 52 .

The control device 50 sequentially calculates the capacitance of the piezoelectric body 83 included in each actuator 88 from actuator 88(1) to actuator 88(n).

Since the sensor switch 542 includes a resistance component, when both the sensor switch 542(2n-1) and the sensor switch 542(2n) are turned on to detect the resonance frequency with the actuator 88(n), the sensor switch 542(2n -1) and the sensor switch 542 (2n), the resistance value between the actuator 88(n) and the sensor circuit 52 is lower than in the case of turning ON one of the sensor switches 542(2n). Therefore, when both the sensor switch 542(2n−1) and the sensor switch 542(2n) are turned on, the resonance frequency can be detected with higher accuracy.
Note that when both the sensor switch 542 (2n-1) and the sensor switch 542 (2n) are turned on to detect the resonance frequency with the actuator 88 (n), the sensor switch 542 (2n-1) and the sensor switch 542 ( 2n), the data amount of the instruction signal output from the control device 50 to the switch control circuit 53 is larger than when one of them is turned on. Therefore, when calculating the capacitance of the n-th piezoelectric body 83(n) that satisfies a predetermined condition, both the sensor switch 542(2n-1) and the sensor switch (2n) are turned on, and the sensor circuit 52 is operated by the actuator 88. (n), and when calculating the capacitance of the n-th piezoelectric body 83(n) that does not satisfy the predetermined condition, , turn on one to detect. When one of the sensor switch 542 (2n-1) and the sensor switch 542 (2n) is turned on, only the sensor switch 542 (2n-1) may be turned on, and only the sensor switch 542 (2n) is turned on. can be

The predetermined condition is, for example, when the capacitance calculation of the n-th piezoelectric body 83 (n) to be executed in the current process is the current capacitance calculation, the previous n-th piezoelectric body 83 (n) stored in the storage unit 55 ( n), the actuator 88(n) is driven more than a certain number of times, whether continuously or intermittently, to cause the nozzle 80 to eject ink. If the actuator 88(n) is driven a certain number of times or more to cause the nozzle 80 to eject ink, it is estimated that the temperature change from the previous calculation is large, so it is necessary to calculate the capacitance with high accuracy. Therefore, both the sensor switch 542(2n-1) and the sensor switch 542(2n) are turned on to detect the resonance frequency with the actuator 88(n) and reduce the influence of the resistance component of the sensor switch 542. FIG. If the number of times the actuator 88(n) is driven is less than a certain number of times, it is assumed that the temperature change from the previous calculation is small, so the control device 50 reduces the data amount of the instruction signal output to the switch control circuit 53. One of the sensor switches 542(2n−1) and 542(2n) is turned on to detect the current.
Alternatively, the predetermined condition may be that a certain period of time or more has elapsed since the previous capacitance calculation of the n-th piezoelectric body 83(n). If a certain amount of time or more has passed since the previous capacitance calculation, it is estimated that the actuator 88 has been driven since the previous calculation, causing the nozzles 80 to eject ink many times and the temperature change to be large. It is necessary to calculate the capacitance with high accuracy.

According to the configuration shown in FIG. 4, since the temperature can be estimated for each actuator 88, more accurate and appropriate control can be performed than when one temperature sensor is provided.

FIG. 5 is a diagram for explaining the difference in resonance waves between the actuator and the sensor circuit depending on the number of sensor switches turned on. The amplitude of the resonance wave between the actuator 88 and the sensor circuit 52 varies depending on the number of the sensor switches 542 that are turned on among the sensor switches 542 electrically connected between the actuator 88 and the sensor circuit 52 . Specifically, when a single sensor switch 542 is turned on, the resistance value between the sensor circuit 52 and the actuator 88 is greater than when a plurality of sensor switches 542 are turned on, so the amplitude is attenuated and reduced. When the amplitude becomes small, it becomes difficult to detect the resonance frequency, so it is necessary to sample at a high sampling rate.

The higher the sampling rate when sampling the resonance frequency of the actuator 88 and the sensor circuit 52, the higher the detection accuracy, but the amount of data processed by the control device 50 increases, so the processing speed decreases. Therefore, when the plurality of sensor switches 542 are turned on, the control device 50 sets the sampling rate to be low when the amplitude of the resonance wave becomes large, and the amplitude of the resonance wave becomes small. If is turned on, set a high sampling rate.

FIG. 6 is an explanatory diagram showing an example of a temperature conversion table. The capacitance of the piezoelectric body 83 with respect to temperature is large when the printing apparatus 1 is manufactured, but decreases with time due to aging. That is, the temperature estimated from the calculated capacitance changes depending on the number of years that have passed since the printing apparatus 1 was manufactured. Therefore, when the control device 50 executes the temperature estimation process, if the number of years since the printing device 1 was manufactured is, for example, less than five years, the control device 50 refers to the first temperature conversion table 551 stored in the storage unit 55, For example, when the number of years elapsed since the manufacturing of the printing apparatus 1 is five years or more, the second temperature conversion table 552 stored in the storage unit 55 is referred to.
Note that the number of temperature conversion tables stored in the storage unit 55 may be three or more, and the temperature conversion tables to be referred to may be further subdivided according to the elapsed years from the time of manufacture of the printing apparatus 1 .

FIG. 7 is a flowchart for explaining the processing of the control device 50 during temperature estimation processing. A case of estimating the temperature of the actuator 88(n) will be described below.

The control device 50 acquires the number of times the actuator 88(n) has been driven since the previous capacitance calculation (S1). The control device 50 determines whether the obtained number of times the actuator 88(n) is driven is equal to or greater than a certain number of times (S2). turns on a plurality of sensor switches 542 electrically connected between and (S3). That is, both the sensor switch 542(2n-1) and the sensor switch 542(2n) are turned on. The controller 50 sets the sampling rate at which the sensor circuit 52 samples the resonance frequency with the actuator 88(n) to a low sampling rate (S4), and the resonance between the actuator 88(n) and the sensor circuit 52 is set. A frequency is obtained from the sensor circuit 52 (S5).

In S2, if the acquired number of times the actuator 88(n) has been driven is less than the predetermined number of times (S2: NO), the control device 50 controls the actuator 88(n) and the sensor circuit 52 to be electrically connected to each other. sensor switch 542 is turned on (S10). That is, only one of the sensor switch 542 (2n-1) and the sensor switch 542 (2n) is turned on. The control device 50 sets the sampling rate at which the sensor circuit 52 samples the resonance frequency with the actuator 88(n) to a high sampling rate (S11), and the resonance between the actuator 88(n) and the sensor circuit 52 is detected. A frequency is obtained from the sensor circuit 52 (S5).

The control device 50 calculates the capacitance of the piezoelectric body 83(n) based on the resonance frequency acquired in S5 (S6). The control device 50 acquires the elapsed years from the printer 1 based on the manufacturing date stored in the storage unit 55 (S7), and selects the temperature conversion table to be referred to based on the acquired elapsed years (S8). . Based on the capacitance calculated in S6, the control device 50 refers to the temperature conversion table selected in S7 to estimate the temperature of the actuator 88(n) (S9), and ends the process.

By performing the above processing, when it is estimated that the temperature change of the actuator 88 is large, the capacitance of the piezoelectric body 83 can be calculated with high accuracy. Also, the temperature of the actuator 88 can be estimated with high accuracy based on the capacitance of the piezoelectric body 83 .

(Embodiment 2)
The present invention will be described below based on the drawings showing a printing apparatus 1 according to Embodiment 2. FIG. Among the configurations according to the second embodiment, the configurations similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. The control device 50 in the first embodiment calculates the capacitance based on the resonance frequency between the sensor circuit 52 and the actuator 88, but in the second embodiment, the charging time (hereinafter, simply charging (also referred to as time).

FIG. 8 is a diagram for explaining the difference in charging time of the actuator due to the difference in electrostatic capacitance of the piezoelectric body. When the piezoelectric body 83 has a large electrostatic capacity, the charging time of the actuator 88 is longer than when the piezoelectric body 83 has a small electrostatic capacity. In this embodiment, the capacitance of the piezoelectric body 83 is calculated using the difference in the charging time to the predetermined voltage of the actuator 88 due to the difference in the capacitance of the piezoelectric body 83 . As the predetermined voltage is set higher, the difference in charging time increases even if the capacitance of the piezoelectric body 83 is small, and the detection resolution (fineness of the capacitance that can be detected with respect to the charging time) increases. time will be longer.

FIG. 9 is a diagram for explaining the difference in actuator charging time depending on the number of sensor switches to be turned on. The charging time of the actuator 88 to a predetermined voltage varies depending on the number of sensor switches 542 that are turned on among the sensor switches 542 electrically connected between the actuator 88 and the sensor circuit 52 . Specifically, when a single sensor switch 542 is turned on, the resistance value between the sensor circuit 52 and the actuator 88 is greater than when a plurality of sensor switches 542 are turned on, resulting in a longer charging time.

As described above, the higher the predetermined voltage is set, the higher the detection resolution, but the longer the charging time. In addition, since the capacitance calculation process is performed, for example, during a time when the nozzles between print pages do not eject ink, the time that the control device 50 can spend on the capacitance calculation process is limited. Therefore, the control device 50 detects the charging time with high resolution by setting a predetermined voltage high when a plurality of sensor switches 542 with a short charging time are turned on, and detects a single sensor switch 542 with a long charging time. is turned on, the predetermined voltage is set low to suppress the time required to detect the charging time.

FIG. 10 is a flowchart for explaining the processing of the control device 50 during temperature estimation processing according to the second embodiment. A case of estimating the temperature of the actuator 88(n) will be described below.

The control device 50 acquires the number of times the actuator 88(n) has been driven since the previous capacitance calculation (S21). The controller 50 determines whether the obtained number of times the actuator 88(n) has been driven is equal to or greater than a certain number of times (S22). turns on a plurality of sensor switches 542 electrically connected between and (S23). That is, both the sensor switch 542(2n-1) and the sensor switch 542(2n) are turned on. The control device 50 sets a high predetermined voltage for detecting the charging time by the sensor circuit 52 (S24), and acquires the charging time up to the predetermined voltage from the sensor circuit 52 (S25).

In S22, if the acquired number of times the actuator 88(n) has been driven is less than the predetermined number of times (S22: NO), the control device 50 controls the actuator 88(n) and the sensor circuit 52 to be electrically connected to each other. sensor switch 542 is turned on (S30). That is, only one of the sensor switch 542 (2n-1) and the sensor switch 542 (2n) is turned on. The control device 50 sets a predetermined voltage at which the sensor circuit 52 detects the charging time to be low (S31), and acquires the charging time up to the predetermined voltage from the sensor circuit 52 (S25).

The control device 50 calculates the capacitance of the piezoelectric body 83 based on the charging time up to the predetermined voltage (S26). S27 to S29 are the same processes as S7 to S9.

By performing the above processing, when it is estimated that the temperature change of the actuator 88 is large, the capacitance of the piezoelectric body 83 can be calculated with high accuracy in a short time. Also, based on the capacitance of the piezoelectric body 83, the temperature of the actuator 88 can be estimated with high accuracy in a short period of time. The sensor circuit 52 may detect the discharge time from the fully charged state of the actuator 88 to a predetermined voltage, and the control device 50 may calculate the capacitance based on the discharge time. Further, the sensor circuit 52 may detect the charging voltage of the actuator 88 and measure the charging time or the discharging time based on the charging voltage of the actuator 88 obtained by the control device 50 from the sensor circuit 52 .

(Embodiment 3)
The present invention will be described below with reference to the drawings showing a printing apparatus 1 according to Embodiment 3. FIG. Among the configurations according to the third embodiment, the configurations similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 11 is a block diagram of the printer 1 according to the third embodiment.

In each of the above-described embodiments, a plurality of sensor switches 542 are electrically connected between all the actuators 88 and the sensor circuits 52. A plurality of sensor switches 542 may be electrically connected between the actuators 88 and only one sensor switch 542 may be electrically connected between the other actuators 88 and the sensor circuit 52 .

As shown in FIG. 11, between the first actuator 88(1) and the sensor circuit 52, a first sensor switch 542(1) and a second sensor switch 542(2) are connected in parallel. Connected between actuator 88(2) and sensor circuit 52 is sensor switch 542(3) (a third sensor switch). Thereafter, a sensor switch 542 (n+1) is electrically connected between the nth actuator 88 (n) and the sensor circuit 52 .

The actuator 88(1), for example, causes a nozzle that ejects white ink, which is frequently ejected because it is used as a base, to eject ink. As in the first embodiment, when a predetermined condition is satisfied, the first sensor switch 542(1) and the second sensor switch 542(2) are turned on to calculate the capacitance of the first piezoelectric body 83(1). , the temperature of actuator 88(1) can be estimated with high accuracy. Also, one sensor switch 542 is electrically connected between the second actuator 88(2) to the n-th actuator 88(n) and the sensor circuit 52, respectively.

With the above configuration, the processing load can be reduced by reducing the number of sensor switches 542 controlled by the control device 50, and the temperature of the actuator 88, which causes the nozzles to eject ink frequently, can be estimated with high accuracy. can do Also, since the number of sensor switches 542 is small, the circuit board can be made small. Note that the number of sensor switches 542 electrically connected in parallel between the sensor circuit 52 and the actuator 88(1) may be three or more. Further, the number of actuators 88 to which a plurality of sensor switches 542 are electrically connected in parallel between the sensor switches 542 is not limited to one. They may be electrically connected in parallel.

(Embodiment 4)
The present invention will be described below based on the drawings showing a printing apparatus 1 according to Embodiment 4. FIG. Among the configurations according to the fourth embodiment, the configurations similar to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 12 is a block diagram of the printer 1 according to the fourth embodiment.

In each of the above-described embodiments, a plurality of sensor switches 542 are electrically connected between the actuator 88 that ejects ink from the nozzle and the sensor circuit 52. However, the actuator 88 that does not eject ink from the nozzle is provided to A plurality of sensor switches 542 are electrically connected between actuators 88 that do not eject ink and sensor circuits 52, and the number of sensor switches 542 electrically connected between other actuators 88 and sensor circuits 52 is set to one. good too.

As shown in FIG. 12, the first actuator 88(1) and the drive circuit 51 are not connected, and a first sensor switch 542(1) is provided between the first actuator 88(1) and the sensor circuit 52. ) and a second sensor switch 542 ( 2 ) are connected in parallel, and a sensor switch 542 ( 3 ) (third sensor switch) is connected between the second actuator 88 ( 2 ) and the sensor circuit 52 . Thereafter, a sensor switch 542 (n+1) is electrically connected between the nth actuator 88 (n) and the sensor circuit 52 . The temperature of the first actuator 88(1) changes due to heat generated by driving the second actuator 88(2) to the n-th actuator 88(n), and the capacitance of the first piezoelectric body 83(1) changes. do. The control device 50 turns on the first sensor switch 542(1) and the second sensor switch 542(2) to calculate the capacitance of the first piezoelectric body 83(1), thereby operating the actuator 88 ( The temperature of 1) can be estimated. That is, the first actuator 88 ( 1 ) is a dedicated actuator for calculating the capacitance of the piezoelectric body 83 .

With the above configuration, the number of sensor switches 542 controlled by the control device 50 is reduced, thereby reducing the processing load and accurately estimating the temperature of the switch section 54 . Note that the first actuator 88 ( n ) may be electrically connected to the drive circuit 51 . Moreover, the number of actuators 88 to which the plurality of sensor switches 542 are electrically connected in parallel between the plurality of sensor switches 542 is not limited to one. 542 may be electrically connected in parallel.

The embodiments disclosed this time should be considered as examples in all respects and not restrictive. The technical features described in each embodiment can be combined with each other, and the scope of the present invention is intended to include all modifications within the scope of the claims and the scope of equivalents to the scope of the claims. be done.

Reference Signs List 1 printing device 50 control device 51 drive circuit 52 sensor circuit 53 switch control circuit 54 switch section 541 drive switch 542 sensor switch 8 inkjet head 80 nozzle 83 piezoelectric body 88 actuator

Claims (11)

a first actuator comprising a first piezoelectric body deformed to eject liquid from the first nozzle;
a sensor electrically connected to the first actuator and detecting a state of the first actuator;
a first sensor switch and a second sensor switch electrically connected in parallel between the first actuator and the sensor;
and a controller that executes a calculation process for calculating the capacitance value of the first piezoelectric body based on the detection result of the sensor. The liquid ejection apparatus according to Claim 1, wherein the controller executes an estimation process of estimating the temperature of the first actuator based on the capacitance value. 3. The liquid ejecting apparatus according to claim 1, wherein the state is a resonance frequency of the sensor and the first actuator. 3. The liquid ejecting apparatus according to claim 1, wherein the state is the time required for the first actuator to be charged to a predetermined voltage. The controller is
Execute a judgment process for judging whether or not a predetermined condition is satisfied,
When it is determined that the predetermined condition is not satisfied, the arithmetic processing is executed by turning ON only the first sensor switch, and when it is determined that the predetermined condition is satisfied, the first sensor switch and the second sensor switch are turned on. 4. The liquid ejecting apparatus according to claim 3, wherein the arithmetic processing is executed in an ON state. 6. The liquid ejecting apparatus according to claim 5, wherein the predetermined condition is that the first actuator has caused the first nozzle to eject the liquid more than a predetermined number of times since the previous capacitance calculation. the sensor detects by sampling the resonant frequency;
The sampling rate at which the resonance frequency is sampled is determined when the arithmetic processing is performed with only the first sensor switch turned on, and when the arithmetic processing is performed with the first sensor switch and the second sensor switch turned on. 7. The liquid ejecting apparatus according to claim 5, wherein the liquid ejecting apparatus is different depending on the case. The controller is
Execute a judgment process for judging whether or not a predetermined condition is satisfied,
When it is determined that the predetermined condition is not satisfied, the arithmetic processing is executed by turning ON only the first sensor switch, and when it is determined that the predetermined condition is satisfied, the first sensor switch and the second sensor switch are turned on. Execute the arithmetic processing by turning on the
The predetermined voltage differs depending on whether the arithmetic processing is performed with only the first sensor switch turned on or when the arithmetic processing is performed with the first sensor switch and the second sensor switch turned on. Item 5. The liquid ejecting apparatus according to item 4. a second actuator electrically connected to the sensor and comprising a second piezoelectric body deformed to eject liquid from a second nozzle;
The liquid ejecting apparatus according to any one of claims 1 to 8, further comprising a third sensor switch electrically connected between the second actuator and the sensor. The first actuator does not cause the first nozzle to eject liquid,
The liquid ejecting apparatus according to claim 9, wherein the second actuator causes the second nozzle to eject liquid. The first actuator causes the first nozzle to eject a first type of liquid,
The liquid ejecting apparatus according to claim 9, wherein the second actuator causes the second nozzle to eject a second type of liquid.

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