JP2010221500A - Apparatus, and method for jetting fluid - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the trouble of the risk that, for example, an IC is broken by heat generation. <P>SOLUTION: The fluid jetting apparatus includes: a plurality of driving signal generation parts which respectively generate driving signals for driving elements that make a fluid jet from nozzles; a plurality of temperature sensors which detect temperatures of the driving signal generation parts; and a control part which makes the driving signal generation parts generate the driving signals. The control part makes the driving signal generation part wait for generation of the driving signal when the detected temperature of the temperature sensor exceeds a first threshold value. The control part determines the first threshold value according to the number of the temperature sensors of detected temperatures which is higher than a second threshold value and lower than the first threshold value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fluid ejecting apparatus and a fluid ejecting method.

As an example of a fluid ejecting apparatus, an ink jet printer that ejects ink by driving a driving element using a driving signal is known. Such a printer is provided with a drive signal generation circuit for generating a drive signal. In addition, the drive signal generation circuit has a current amplification circuit composed of a transistor pair of two transistors (NPN type transistor and PNP transistor).
By the way, such a transistor pair generates heat when generating a drive signal. When this heat generation becomes large, the transistor may be destroyed. In view of this, a temperature sensor that detects the temperature of the transistor is provided, and when the detected temperature of the temperature sensor reaches a threshold value (a control threshold value described later), measures are taken so that the transistor is not destroyed (for example, Patent Documents). 1).

JP 2007-276174 A

In some cases, a plurality of transistor pairs are provided for speeding up printing. In this case, even if the heat generation of each transistor is less than or equal to the threshold, if each transistor pair generates heat as a whole, for example, an IC provided on the same substrate as the transistor pair may be destroyed. There was a problem.
Therefore, an object of the present invention is to prevent problems caused by heat generation.

The main invention for achieving the above object is to provide a plurality of drive signal generators that respectively generate drive signals for driving a drive element that ejects fluid from a nozzle, and a plurality of drive signal generators that detect the temperature of the drive signal generator. A temperature sensor and a control unit that causes the drive signal generation unit to generate the drive signal, wherein the drive signal generation unit generates the drive signal when a detected temperature of the temperature sensor exceeds a first threshold value. A standby control unit, wherein the control unit determines the first threshold value according to the number of the temperature sensors having a detected temperature higher than a second threshold value lower than the first threshold value. The fluid ejecting apparatus.
Other features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

1 is a block diagram of an overall configuration of a printer. FIG. 2A is a perspective view of the printer. FIG. 2B is a cross-sectional view of the printer. It is explanatory drawing of a structure of the drive signal generation circuit of a reference example. It is explanatory drawing of operation | movement of the drive signal generation circuit of a reference example. It is explanatory drawing of multi COM. It is a figure which shows arrangement | positioning on the board | substrate of each transistor and thermistor of a drive signal generation circuit. It is the figure which looked at a part of FIG. 6 from the side. It is a flowchart of necessity determination of standby operation. It is a flowchart of the count process of the number of thermistors whose detected temperature is more than the determination threshold Ta. It is a determination table of a control threshold used when determining control threshold Tb. It is explanatory drawing of the Example of this embodiment. It is a figure which shows the modification of arrangement | positioning of a thermistor. It is a figure which shows another modification of arrangement | positioning of a thermistor. It is a figure which shows the modification of a structure of a heat sink. It is the figure which looked at FIG. 14 from the top. It is a figure which shows another modification of a structure of a heat sink. It is the figure which looked at FIG. 16 from the top. It is a figure which shows the modification about a board | substrate.

  At least the following matters will become clear from the description of the present specification and the accompanying drawings.

A plurality of drive signal generation units that respectively generate drive signals for driving the drive elements that eject the fluid from the nozzles, a plurality of temperature sensors that detect the temperature of the drive signal generation unit, and the drive signal generation unit A control unit that generates a drive signal, the control unit causing the drive signal generation unit to wait for generation of the drive signal when a temperature detected by the temperature sensor exceeds a first threshold, and the control The unit determines the first threshold value according to the number of the temperature sensors whose detected temperature is higher than the second threshold value which is lower than the first threshold value.
According to such a fluid ejecting apparatus, problems due to heat generation can be prevented.

The fluid ejecting apparatus may further include a storage unit that stores a table in which the number of the temperature sensors having a detected temperature higher than the second threshold is associated with the first threshold, and the control unit includes the table It is desirable to determine the first threshold by referring to.
According to such a fluid ejecting apparatus, the first threshold value can be easily set based on the detected temperature of each temperature sensor.

In the fluid ejecting apparatus, it is preferable that the table does not include the first threshold value when the temperature sensor having a detected temperature higher than the second threshold value is not provided.
According to such a fluid ejecting apparatus, the amount of data to be stored in the storage unit can be reduced.

  In such a fluid ejecting apparatus, even if the plurality of drive signal generation units are provided on the same substrate, the IC provided on the substrate can be prevented from being destroyed by heat.

In the fluid ejecting apparatus, the control unit compares the highest detected temperature among the detected temperatures of the plurality of temperature sensors with the first threshold value, and the detected temperature exceeds the first threshold value. Further, it is preferable that the drive signal generation unit waits for generation of the drive signal.
According to such a fluid ejecting apparatus, only one detected temperature needs to be compared with the first threshold value, and the processing can be simplified.

  In addition, the fluid ejection method of the fluid ejection device includes a plurality of drive signal generation units that respectively generate drive signals for driving the drive elements that eject the fluid from the nozzles, According to the number of the temperature sensors that generate a drive signal, detect the temperature of the plurality of drive signal generation units with a temperature sensor, and have a detected temperature higher than a second threshold lower than the first threshold, Determining a first threshold; and causing the drive signal generator to wait for generation of the drive signal when a temperature detected by the temperature sensor exceeds the first threshold. It becomes clear.

  In the following embodiments, an ink jet printer (hereinafter also referred to as a printer 1) will be described as an example of the liquid ejecting apparatus.

=== Printer configuration ===
FIG. 1 is a block diagram of the overall configuration of the printer 1. FIG. 2A is a perspective view of the printer 1. FIG. 2B is a cross-sectional view of the printer 1. Hereinafter, a basic configuration of the printer will be described.

  The printer 1 includes a transport unit 20, a carriage unit 30, a head unit 40, a detector group 50, and a controller 60. The printer 1 that has received print data from the computer 110 that is an external device controls each unit (the conveyance unit 20, the carriage unit 30, and the head unit 40) by the controller 60. The controller 60 controls each unit based on the print data received from the computer 110 and prints an image on a medium. The situation in the printer 1 is monitored by the detector group 50, and the detector group 50 outputs the detection result to the controller 60. The controller 60 controls each unit based on the detection result output from the detector group 50.

  The transport unit 20 is for transporting a medium (for example, paper) in a predetermined direction (hereinafter referred to as a transport direction). The transport unit 20 includes a paper feed roller 21, a transport motor 22 (also referred to as a PF motor), a transport roller 23, a platen 24, and a paper discharge roller 25. The paper feed roller 21 is a roller for feeding the paper inserted into the paper insertion slot into the printer. The transport roller 23 is a roller that transports the paper fed by the paper feed roller 21 to a printable area, and is driven by the transport motor 22. The platen 24 supports the paper being printed. The paper discharge roller 25 is a roller for discharging the paper to the outside of the printer, and is provided on the downstream side in the transport direction with respect to the printable area.

  The carriage unit 30 is for moving (also referred to as “scanning”) the head in a predetermined direction (hereinafter referred to as a moving direction). The carriage unit 30 includes a carriage 31 and a carriage motor 32 (also referred to as a CR motor). The carriage 31 can reciprocate in the moving direction and is driven by a carriage motor 32. Further, the carriage 31 detachably holds an ink cartridge that stores ink.

  The head unit 40 is for ejecting ink onto paper. The head unit 40 includes a head 41 having a plurality of nozzles. Since the head 41 is provided on the carriage 31, when the carriage 31 moves in the movement direction, the head 41 also moves in the movement direction. Then, by intermittently ejecting ink while the head 41 is moving in the moving direction, dot lines (raster lines) along the moving direction are formed on the paper.

The detector group 50 includes a linear encoder 51, a rotary encoder 52, a paper detection sensor 53, an optical sensor 54, and the like. The linear encoder 51 detects the position of the carriage 31 in the moving direction. The rotary encoder 52 detects the rotation amount of the transport roller 23. The paper detection sensor 53 detects the position of the leading edge of the paper being fed. The optical sensor 54 detects the presence / absence of paper by a light emitting unit and a light receiving unit attached to the carriage 31. Then, the optical sensor 54 can detect the position of the edge of the sheet while moving by the carriage 31, and can detect the width of the sheet. The optical sensor 54 also detects the leading edge (the end on the downstream side in the transport direction, also referred to as the upper end) and the rear end (the end on the upstream side in the transport direction, also referred to as the lower end) depending on the situation. it can.
Although not shown here, a thermistor S that detects the temperature of the transistors of the drive signal generation circuit 65 of the controller 60 is also provided as the detector group 50 (described later).

  The controller 60 (corresponding to a control unit) is a control unit for controlling the printer. The controller 60 includes an interface unit 61, a CPU 62, a memory 63, a unit control circuit 64, and a drive signal generation circuit 65. The interface unit 61 transmits and receives data between the computer 110 that is an external device and the printer 1. The CPU 62 is an arithmetic processing unit for controlling the entire printer. The memory 63 is for securing an area for storing a program of the CPU 62, a work area, and the like, and includes storage elements such as a RAM and an EEPROM. The CPU 62 controls each unit via the unit control circuit 64 in accordance with a program stored in the memory 63.

  In addition, the drive signal generation circuit 65 generates a drive signal COM for driving the piezo element PZT of the head unit 40. Although only one transmission line of the drive signal COM in the drawing is drawn, in reality, a large number of drive signals COM are generated by the drive signal generation circuit 65 and transmitted to the head unit 40.

<Printing procedure>
When receiving a print command and print data from the computer 110, the controller 60 analyzes the contents of various commands included in the print data, and performs the following processing using each unit.
First, the controller 60 rotates the paper feed roller 21 to feed the paper to be printed to the conveyance roller 23. Next, the controller 60 rotates the transport roller 23 by driving the transport motor 22. When the transport roller 23 rotates with a predetermined rotation amount, the paper is transported with a predetermined transport amount.

  When the sheet is conveyed to the lower part of the head unit 40, the controller 60 rotates the carriage motor 32 based on the print command. In response to the rotation of the carriage motor 32, the carriage 31 moves in the movement direction. Further, as the carriage 31 moves, the head unit 40 provided on the carriage 31 also moves in the moving direction at the same time. Then, the controller 60 intermittently ejects ink droplets from the head 41 while the head unit 40 is moving in the movement direction. When the ink droplets land on the paper, a dot row in which a plurality of dots are arranged in the moving direction is formed. A dot forming operation by ejecting ink from the moving head 41 is called a pass.

Further, the controller 60 drives the transport motor 22 while the head unit 40 reciprocates. The transport motor 22 generates a driving force in the rotation direction according to the commanded driving amount from the controller 60. And the conveyance motor 22 rotates the conveyance roller 23 using this driving force. When the transport roller 23 rotates with a predetermined rotation amount, the paper is transported with a predetermined transport amount. That is, the conveyance amount of the paper is determined according to the rotation amount of the conveyance roller 23. In this way, the pass and the transport operation are alternately repeated to form dots on each pixel of the paper. Thus, an image is printed on the paper.
Finally, the controller 60 discharges the paper on which printing has been completed by the paper discharge roller 25 that rotates in synchronization with the transport roller 23.

=== Drive Signal Generation Circuit ===
<Reference example>
FIG. 3 is an explanatory diagram of the configuration of the drive signal generation circuit of the reference example. The drive signal generation circuit 65 illustrated in FIG. 3 includes a D / A converter (hereinafter also referred to as DAC) 651 and a current amplification circuit 652.

Drive signal data (digital data) is input to the DAC 651 from the CPU 62. The DAC 651 converts this digital data into an analog signal and outputs an original drive signal corresponding to the drive signal data. The original drive signal is substantially the same signal as the drive signal COM.
The current amplifying circuit 652 is a circuit for supplying a sufficient current so that a large number of piezoelectric elements can operate without any trouble. The current amplifier circuit 652 charges and discharges the piezo element (capacitive load) in accordance with the voltage change of the input original drive signal. The current amplifier circuit 652 includes a charge side transistor Q1 and a discharge side transistor Q2. The charge side transistor Q1 is an NPN type transistor, and the discharge side transistor Q2 is a PNP type transistor.

The original drive signal from the DAC 651 is input to the base of the charge side transistor Q1 (NPN type transistor). The collector of the charge side transistor Q1 is connected to the 42V power source, the emitter of the charge side transistor Q1 is connected to the emitter of the discharge side transistor Q2, and is connected to the output signal line of the drive signal COM to the piezo element. Has been.
The original drive signal from the DAC 651 is inputted to the base of the discharge side transistor Q2 (PNP transistor). The collector of the discharge side transistor Q2 is connected to the ground (GND), and the emitter of the discharge side transistor Q2 is connected to the emitter of the charge side transistor Q1.

  Next, the operation of the drive signal generation circuit 65 of the reference example will be described. FIG. 4 is an explanatory diagram of the operation of the drive signal generation circuit 65 of the reference example.

(When charging)
When the piezo element is charged, the voltage of the original drive signal from the DAC 651 gradually increases. As a result, the charge-side transistor Q1 is turned on, and a current I1 flows as shown in the figure to charge the piezo element. The amount of heat generated (power consumption) of the charging side transistor Q1 at this time is represented by the product of the voltage between the collector and the emitter of the charging side transistor Q1 and the current I1. That is, the product is the product of the current I1 and the hatched portion on the left side of FIG.

(Hold)
At the time of holding, the voltage of the original drive signal does not change. As a result, both the charge side transistor Q1 and the discharge side transistor Q2 are turned off. Therefore, no current flows and the drive signal COM maintains the same voltage.

(During discharge)
When the piezo element is discharged, the voltage of the original drive signal from the DAC 651 gradually decreases. As a result, the discharge-side transistor Q2 is turned on, and a current I2 flows as shown in the figure to discharge the piezo element. The amount of heat generated (power consumption) of the discharge side transistor Q2 at this time is expressed by the product of the collector-emitter voltage of the discharge side transistor Q2 and the current I2. That is, the product is the product of the current I2 and the hatched portion on the right side of FIG.
Thus, when the piezo element is charged, the charge side transistor Q1 generates heat, and when the piezo element is discharged, the discharge side transistor Q2 generates heat.

<Drive signal generation circuit of this embodiment>
In printing with a printer, it is desired to increase the printing speed. As a method for increasing the printing speed, it is conceivable to increase the dot formation speed and increase the number of nozzles.

  Increasing the speed of dot formation shortens the period for forming dots in one pixel. In the drive signal generation circuit 65, the same drive signal COM is repeatedly generated every time a dot is formed in each pixel. By shortening the period (repetition period T) corresponding to one pixel of the drive signal COM, the moving speed of the carriage 31 during the pass can be increased, and thereby the printing speed can be increased. Thus, it is desirable to shorten the repetition period T of the drive signal COM. Therefore, in this embodiment, multi-COM is adopted.

FIG. 5 is an explanatory diagram of multi-COM.
The drive signal COM_A has three drive pulses PS1, PS2, and PS3 in the repetition period T. The drive signal COM_B has two drive pulses PS4 and PS5 in the repetition period T. A drive pulse is selected and applied to the piezo element according to the pixel data.

  For example, when dots are not formed (when the pixel data is [00]), the drive pulse PS5 of the drive signal COM_B is selected and applied to the piezo element. When a small dot is formed (when the pixel data is [01]), the drive pulse PS4 of the drive signal COM_B is selected and applied to the piezo element. When medium dots are formed (when the pixel data is [10]), the drive pulse PS2 of the drive signal COM_A is selected and applied to the piezo element. When large dots are formed (when the pixel data is [11]), the drive pulses PS1, PS2, and PS3 of the drive signal COM_A are selected and applied to the piezo elements.

  Thereby, the repetition period T can be shortened as compared with the case where the five drive pulses are included in one drive signal COM. However, when two types of drive signals are generated in this way, two current amplifier circuits are required. That is, two combinations (transistor pairs) of the charge side transistor Q1 and the discharge side transistor Q2 are required.

  The increase in the number of nozzles is to increase the number of nozzles of the head 41. By increasing the number of nozzles of the head 41, it is possible to increase the area in which dots are formed in one pass, thereby increasing the printing speed. However, in this case, the number of piezoelectric elements that are driven during the pass increases. For this reason, when trying to drive all the piezo elements with one drive signal COM, it is necessary to flow a large current through each transistor of the drive signal generation circuit 65. As a result, the heat generation of one transistor increases, and the transistor may be destroyed by heat. Therefore, the drive signal COM is generated for each nozzle row of each color.

  As a result, the drive signal generation circuit 65 of this embodiment is provided with a plurality of transistor pairs. Specifically, two transistor pairs, that is, 16 transistors are provided for each of four colors (CMYK). Each transistor pair corresponds to a drive signal generation unit.

=== Thermistor arrangement ===
6 is a diagram showing the arrangement of the transistors and the thermistor S of the drive signal generation circuit 65 on the substrate 72, and FIG. 7 is a diagram of a part of FIG. 6 viewed from the side. In FIG. 6, the heat sink 70 shown in FIG. 7 is omitted.
In FIG. 6, a portion surrounded by a dotted line indicates a transistor pair. Of each transistor pair, the charge side transistor is indicated by symbol n, and the discharge side transistor is indicated by symbol p. Further, the numbers after the symbols n and p indicate the numbers of transistor pairs. For example, n1 and p1 in the figure indicate the same transistor pair, n1 is a charge side transistor (NPN type transistor), and p1 is a discharge side transistor (PNP type transistor).

As shown in FIG. 6, regions are formed for each of the four colors on the substrate 72, and two transistor pairs are arranged side by side in the Y direction in each region. Further, the charge side transistor and the discharge side transistor of each transistor pair are arranged side by side in the X direction in the figure. The −X side is a charge side transistor, and the + X side is a discharge side transistor.
The thermistor S is arranged at the center of the four transistors of each color. That is, four thermistors S are arranged on the substrate 72. The numbers in the thermistor S indicate the order of processing in the count processing (FIG. 9) described later.
Further, as shown in FIG. 7, a heat sink 70 is provided so as to be in contact with the upper surface of each transistor. The heat sink 70 releases heat generated in each transistor to the outside of the printer 1.

=== Standby operation ===
<Reference example>
As described above, the drive signal generation circuit 65 has a plurality of transistor pairs. Each transistor pair generates heat when it generates the drive signal COM. If the temperature of the transistor itself becomes high due to this heat generation, the transistor may be destroyed.
Therefore, the printer 1 performs a standby operation in order to prevent the transistor from being destroyed. The standby operation is to wait for a predetermined time when the detected temperature of the thermistor S reaches a threshold (hereinafter, this threshold is referred to as a control threshold) in order to prevent the transistor from being destroyed by heat. This is the action to be performed.
In this reference example, when the detected temperature of any one of the thermistors S in FIG. 6 reaches the control threshold value of 80 ° C., the standby operation is performed.
This standby operation suppresses heat generation of the transistor, so that the transistor can be prevented from being destroyed.

<This embodiment>
In the reference example, the detection temperature of all thermistors S may be close to 80 ° C. If the total heat generation amount of the entire drive signal generation circuit 65 becomes too high, other ICs on the substrate 72 may be destroyed even if the transistors are not destroyed. Therefore, in the present embodiment, the control threshold value for determining whether or not the standby operation is necessary is changed according to the total heat generation amount of the drive signal generation circuit 65. Note that a threshold lower than the control threshold (hereinafter, this threshold is referred to as a determination threshold) is used for determining whether or not the standby operation is necessary in the present embodiment. That is, if the determination threshold is Ta and the control threshold is Tb, Ta <Tb. The control threshold Tb corresponds to the first threshold, and the determination threshold Ta corresponds to the second threshold.

FIG. 8 is a flowchart for determining whether or not the standby operation is necessary.
The controller 60 compares the detection temperature of each thermistor S with the determination threshold value Ta, and counts the number N of thermistors S whose detection temperature is equal to or higher than the determination threshold value Ta (S101).
Hereinafter, this count (count process) will be described.

FIG. 9 is a flowchart of the counting process of the number of thermistors whose detected temperature is equal to or higher than the determination threshold Ta.
First, the controller 60 sets the number N of the thermistors S whose detected temperature is equal to or higher than the determination threshold Ta, the number i of the thermistor S, and the maximum detected temperature Tmax to the initial value (0) (S201).
Next, the controller 60 increments i (S202). Since i = 0 at the beginning, i = 0 + 1 = 1.
Then, the controller 60 compares the detected temperature Ti of the i-th thermistor S with the determination threshold Ta (S203). Since i = 1 here, the detection temperature T1 of the first thermistor S (the thermistor at the upper left in FIG. 6) is compared with the determination threshold Ta. If the detected temperature Ti is equal to or higher than Ta (YES in S204), N is incremented (S205).

Next, the controller 60 compares the detected temperature Ti of the i-th thermistor S with the maximum detected temperature Tmax stored in the memory 63 (S206). If the detected temperature Ti is higher than the maximum detected temperature Tmax (S207), the detected temperature Ti is set to the maximum detected temperature Tmax (S208) and stored in the memory 63. In the case of the first thermistor S, the highest detected temperature Tmax to be compared is 0 as an initial value. Therefore, the detected temperature T1 of the first thermistor S is stored in the memory 63 as the maximum detected temperature Tmax.
Then, the controller 60 determines whether there is a next thermistor S (S209). If it is determined that there is the next thermistor S (YES in S209), the process returns to S202 and i is incremented. When i = 1, i = 2 and the same processing is performed for the second thermistor S (the thermistor at the upper right in FIG. 6).

As described above, the controller 60 repeatedly performs the processes of S202 to S208 for the four thermistors S. If it is determined in S209 that there is no next thermistor S (NO in S209), the counting process is terminated. By this counting process, the number N of thermistors S whose detected temperature has reached the determination threshold Ta and the highest detected temperature Tmax among the thermistor S detected temperatures Ti are obtained.
Then, the controller 60 determines the control threshold value Tb based on the number N of thermistors S whose detected temperature is equal to or higher than the determination threshold value Ta based on the count processing result (FIG. 8: S102).

FIG. 10 is a control threshold determination table used when determining the control threshold Tb. As shown in the figure, in this table, the number N of thermistors S whose detected temperature is equal to or higher than the determination threshold Ta is associated with the control threshold Tb. This table is stored in the memory 63 of the controller 60.
For example, the controller 60 determines the control threshold Tb to be 80 ° C. when the number of thermistors S whose detected temperature is equal to or higher than the determination threshold Ta is one. Similarly, when the number of thermistors S having a detected temperature equal to or higher than the determination threshold Ta is two, the control threshold Tb is determined to be 70 ° C., and in the case of three, the control threshold Tb is determined to be 60 ° C. In this case, the control threshold value Tb is determined to be 50 ° C. Note that when the number of thermistors S whose detected temperature is equal to or higher than the determination threshold Ta is 0, the control threshold Tb is not set. This is because the standby operation is not necessary if the detected temperatures of all thermistors S are equal to or lower than the determination threshold value Ta. Thereby, the amount of data to be stored can be reduced.

  Next, the controller 60 compares the maximum detected temperature Tmax among the detected temperatures of the thermistor S with the control threshold Tb (FIG. 8: S103). If the maximum detected temperature Tmax is lower than the control threshold Tb (FIG. 8: NO in S104), it is determined that the standby operation is unnecessary (FIG. 8: S105). On the other hand, if the maximum detected temperature Tmax is equal to or higher than the control threshold Tb (FIG. 8: YES in S104), it is determined that a standby operation is necessary (FIG. 8: S106).

FIG. 11 is an explanatory diagram of an example of this embodiment.
In this embodiment, the determination threshold is 45 ° C. In the figure, ◯ indicates that the temperature detection of the thermistor is lower than the determination threshold, and x indicates that the temperature detected by the thermistor is equal to or higher than the determination threshold.

  The controller 60 first counts the number of thermistors S that have reached the determination threshold (45 ° C.). In Example 1, the detected temperature of one (fourth) of the four thermistors S is equal to or higher than the determination threshold. Therefore, since the number N of the thermistors S counted in the counting process is one, the controller 60 refers to the table of FIG. 10 and determines the control threshold value at 80 ° C. Then, the controller 60 compares the maximum detected temperature Tmax (in this case, the detected temperature of the 4th thermistor) obtained by the counting process with the control threshold (80 ° C.), and the maximum detected temperature Tmax is 80 ° C. or higher. If so, it is determined that the standby operation is necessary, and if the maximum detected temperature Tmax is lower than 80 ° C., it is determined that the standby operation is unnecessary.

  In Example 2, two (No. 3 and No. 4) detection temperatures of the four thermistors S are equal to or higher than the determination threshold. Accordingly, since the number N of the thermistors S counted in the counting process is two, the controller 60 refers to the table of FIG. Then, the controller 60 compares the maximum detected temperature Tmax obtained by the count process with the control threshold (70 ° C.), and determines that the standby operation is necessary if the maximum detected temperature Tmax is 70 ° C. or higher. If the temperature Tmax is lower than 70 ° C., it is determined that the standby operation is unnecessary.

  In Example 3, the detected temperature of three (No. 2, No. 3, No. 4) of the four thermistors S is equal to or higher than the determination threshold. Therefore, since the number N of the thermistors S counted in the counting process is 3, the controller 60 refers to the table of FIG. 10 and determines the control threshold value at 60 ° C. Then, the controller 60 compares the maximum detected temperature Tmax obtained by the count process with the control threshold (60 ° C.), and determines that the standby operation is necessary if the maximum detected temperature Tmax is 60 ° C. or higher. If the temperature Tmax is lower than 60 ° C., it is determined that the standby operation is unnecessary.

  In Example 4, all four thermistors S are equal to or greater than the determination threshold. Since the number N of the thermistors S counted in the counting process is four, the controller 60 refers to the table of FIG. 10 and determines the control threshold value at 50 ° C. Then, the controller 60 compares the maximum detected temperature Tmax with the control threshold (50 ° C.), determines that the standby operation is necessary if the maximum detected temperature Tmax is 50 ° C. or higher, and the maximum detected temperature Tmax is higher than 50 ° C. If it is lower, it is determined that the standby operation is unnecessary.

As described above, the printer 1 of the present embodiment includes a plurality of transistor pairs that respectively generate drive signals COM for driving the piezo elements that eject ink from the nozzles, and a plurality of thermistors S that detect the temperatures of the transistor pairs. A controller that causes the transistor pair to generate the drive signal COM, and that causes the transistor pair to wait for generation of the drive signal COM when the detected temperature of the thermistor S exceeds the control threshold value Tb. Then, the controller 60 determines the value of the control threshold Tb according to the number of thermistors S having a detected temperature higher than a determination threshold (for example, 45 ° C.) lower than the control threshold Tb.
Thereby, the standby operation can be performed in accordance with the total heat generation amount of the entire transistor pair, so that problems due to heat generation (destruction or failure of the transistor or IC, etc.) can be prevented.

=== Modification ===
<About thermistor placement>
In the embodiment described above, one thermistor S is arranged for two transistor pairs (four transistors), but the present invention is not limited to this.
FIG. 12 is a diagram illustrating a modified example of the thermistor arrangement. In the figure, a thermistor S is arranged for each transistor. That is, 16 thermistors S are provided.
Moreover, FIG. 13 is a figure which shows another modification of arrangement | positioning of a thermistor. In the figure, one thermistor S is arranged for each transistor pair. That is, eight thermistors S are provided.
Even in such a case, if the correspondence relationship between the number N of the thermistors S whose detected temperature has reached the determination threshold Ta and the control threshold Tb is determined in advance, the same processing as in the above-described embodiment can be performed. The effect is obtained.

<About heat sink configuration>
In the above-described embodiment, the lower surface of the heat sink 70 is in contact with the upper surface of each transistor. However, the present invention is not limited to this.
FIG. 14 is a view showing a modified example of the configuration of the heat sink, and FIG. 15 is a view of FIG. 14 as viewed from above. In this modification, a thermistor S is provided for each transistor pair.
As shown in the figure, in this modification, two heat sinks 70 are provided. The transistors are arranged in contact with the side surfaces of the two heat sinks 70 along the X direction. A thermistor S is arranged between the transistor pair.
FIG. 16 is a diagram showing another modification of the configuration of the heat sink, and FIG. 17 is a diagram of FIG. 16 viewed from above.
In this modification, the transistors are arranged in contact with the four side surfaces of the heat sink 70. A thermistor S is arranged between the transistor pair.

<About substrate>
In the above-described embodiment, all the transistors are provided on the same substrate 72. However, all the transistors need not be provided over the same substrate.
FIG. 18 is a diagram illustrating a modification of the substrate. In this modification, transistor pairs (n1, p1, n8, p8) are arranged so as to be in contact with the side surface of the heat sink 70. The transistors n1 and p1 are formed on the substrate 72a, and the transistors n8 and p8 are formed on the substrate 72b.
Even in such a case, the transistors and ICs on each substrate can be prevented from being destroyed by the same processing as that of the above-described embodiment.

=== Other Embodiments ===
Although a printer or the like as one embodiment has been described, the above embodiment is for facilitating the understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and it is needless to say that the present invention includes equivalents thereof. In particular, the embodiments described below are also included in the present invention.

<About liquid ejecting device>
In the above-described embodiment, an ink jet printer is described as an example of the liquid ejecting apparatus. However, the liquid ejecting apparatus is not limited to the ink jet printer, and liquids other than ink (including liquids in which functional material particles are dispersed and liquids such as gels other than liquids) and liquids are also used. The present invention is also applicable to a fluid ejecting apparatus that ejects a fluid (a solid that can be ejected as a fluid, such as powder). For example, an injection device for injecting a liquid colorant or an electrode material used for manufacturing a liquid crystal display, an EL display and a surface emitting display, or an injection device for injecting a liquid bioorganic material used for biochip manufacturing The embodiment may be applied.

<About ink>
Since the above-described embodiment is an embodiment of the printer, the ink is ejected from the nozzle. However, the ink may be water-based or oil-based. Further, the fluid ejected from the nozzle is not limited to ink. For example, liquids (including water) including metal materials, organic materials (especially polymer materials), magnetic materials, conductive materials, wiring materials, film forming materials, electronic ink, processing liquids, gene solutions, etc. are ejected from nozzles. May be.

<About thermistors>
In the above-described embodiment, the thermistor S is used to detect the heat generation temperature of the transistor. However, the present invention is not limited to this. A temperature sensor other than the thermistor S, such as a diode, may be used.

<About piezo elements>
In the above-described embodiment, ink is ejected using a piezo element. However, the present invention is not limited to this, and a driving element other than the piezo element, for example, a heating element may be used.

<About transistor pairs>
In the embodiment described above, the number of transistor pairs provided in the drive signal generation circuit 65 is eight (16 transistors). However, the present invention is not limited to this, and a plurality of transistor pairs (two or more) are provided. Just do it.

1 printer 20 transport unit, 21 paper feed roller, 22 transport motor (PF motor),
23 transport roller, 24 platen, 25 discharge roller,
30 Carriage unit, 31 Carriage,
32 Carriage motor (CR motor),
40 head units, 41 heads,
50 detector groups, 51 linear encoder, 52 rotary encoder,
53 Paper detection sensor, 54 Optical sensor,
60 controller, 61 interface, 62 CPU,
63 memory, 64 unit control circuit, 65 drive signal generation circuit,
70 heat sink, 72 substrate,
110 computers,
S thermistor

Claims (6)

A plurality of drive signal generation units that respectively generate drive signals for driving the drive elements that eject the fluid from the nozzles;
A plurality of temperature sensors for detecting the temperature of the drive signal generation unit;
A control unit that causes the drive signal generation unit to generate the drive signal, and causes the drive signal generation unit to wait for generation of the drive signal when a temperature detected by the temperature sensor exceeds a first threshold. When,
With
The said control part determines the said 1st threshold value according to the number of the said temperature sensors whose detected temperature is higher than the 2nd threshold value lower than the said 1st threshold value, The fluid ejection apparatus characterized by the above-mentioned. The fluid ejection device according to claim 1,
A storage unit storing a table in which the number of the temperature sensors having a detected temperature higher than the second threshold is associated with the first threshold;
The control unit determines the first threshold value by referring to the table.
A fluid ejecting apparatus. The fluid ejecting apparatus according to claim 2,
In the table, the first threshold value is not prepared when there is no temperature sensor whose detected temperature is higher than the second threshold value.
A fluid ejecting apparatus. The fluid ejection device according to any one of claims 1 to 3,
The plurality of drive signal generation units are provided on the same substrate.
A fluid ejecting apparatus. The fluid ejecting apparatus according to claim 1,
The control unit compares the first detected temperature of the detected temperatures of the plurality of temperature sensors with the first threshold value, and when the detected temperature exceeds the first threshold value, Waiting for the generation of the drive signal;
A fluid ejecting apparatus. A fluid ejecting method of a fluid ejecting apparatus including a plurality of drive signal generating units that respectively generate drive signals for driving a drive element that ejects fluid from a nozzle, wherein the drive signals are generated by a plurality of the drive signal generating units. Generating,
Detecting the temperature of the plurality of drive signal generation units with a temperature sensor;
Determining the first threshold according to the number of temperature sensors having a detected temperature higher than a second threshold lower than the first threshold;
When the detected temperature of the temperature sensor exceeds the first threshold, causing the drive signal generator to wait for generation of the drive signal;
A fluid ejection method comprising:

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