JP2017121738A - Liquid jet device, and control method and control device of liquid jet head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid jet device capable of adjusting properly an internal temperature of a liquid jet head.SOLUTION: A liquid jet device includes a liquid jet head for jetting liquid by changing a pressure in a pressure chamber filled with liquid corresponding to drive signal COM by a driving element, a detection part 46 for detecting residual vibration in the pressure chamber when supplying a drive signal to the driving element, an estimation part 34 for specifying an estimated temperature in the liquid jet head from the residual vibration detected by the detection part, and a control part 32 for allowing a cooling action for lowering a temperature in the liquid jet head to be executed corresponding to the estimated temperature specified by the estimation part.SELECTED DRAWING: Figure 2

Description

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

  In the technique of ejecting a liquid such as ink, a rise in temperature of the liquid ejecting head due to heat generated by a drive circuit or the like becomes a problem. From the viewpoint of solving this problem, for example, Patent Document 1 discloses an image forming apparatus in which temperature sensors are installed in a supply port for supplying ink to a recording head and a discharge port for discharging ink from the recording head. Has been. In the configuration of Patent Document 1, the ink temperature of the recording head is adjusted so that the ink temperature calculated from the detection result of each temperature sensor is a temperature within a predetermined range.

JP 2010-284824 A

  In the technique of Patent Document 1, since the temperature is detected at the supply port and the discharge port of the recording head, it is difficult to detect the temperature of the ink inside the recording head with high accuracy. Therefore, it is actually not easy to appropriately adjust the temperature inside the recording head to the target temperature. In view of the above circumstances, an object of the present invention is to appropriately adjust the temperature inside the liquid jet head.

  In order to solve the above problems, a liquid ejecting apparatus of the present invention includes a liquid ejecting head that ejects liquid by causing a driving element to vary the pressure in a pressure chamber filled with liquid according to a driving signal, and the driving element. A detection unit that detects residual vibration in the pressure chamber when a driving signal is supplied to the sensor, an estimation unit that identifies an estimated temperature in the liquid jet head from the residual vibration detected by the detection unit, and a temperature in the liquid jet head that decreases And a control unit that executes a cooling operation for causing the cooling unit to execute the cooling operation according to the estimated temperature specified by the estimation unit. In the above aspect, since the estimated temperature in the liquid ejecting head is specified from the residual vibration in the pressure chamber, the liquid ejecting head of the liquid ejecting head is compared with the technique of Patent Document 1 that detects the temperature at the supply port or the discharge port, for example. It is possible to estimate the internal temperature appropriately.

  In a preferred aspect of the present invention, the control unit causes the liquid ejecting head to execute a standby operation for waiting for liquid ejection as a cooling operation, and sets a standby time for the standby operation according to the estimated temperature. In the above aspect, since the liquid ejecting head is instructed as a cooling operation to wait for the liquid to be ejected, the liquid is not consumed as compared with the configuration in which the internal temperature of the liquid ejecting head is decreased by discharging the liquid. There is an advantage that the internal temperature of the liquid jet head can be lowered. In addition, since the standby time of the standby operation is set according to the estimated temperature, the standby time of an appropriate standby time with respect to the actual internal temperature of the liquid ejecting head is compared with the configuration in which the standby time is fixed to a predetermined value. The operation can be performed by the liquid ejecting head.

  In a preferred aspect of the present invention, the control unit causes the liquid ejecting head to execute a flushing operation for ejecting liquid by driving the drive element by supplying a drive signal as a cooling operation, and the amount of liquid ejected by the flushing operation is estimated temperature Set according to. In the above aspect, since the flushing operation for ejecting the liquid by the drive of the drive element is instructed to the liquid ejecting head, the internal temperature of the liquid ejecting head can be effectively lowered by the flow and ejection of the heated liquid. It is. In addition, since the ejection amount by the flushing operation is set according to the estimated temperature, compared with a configuration in which the ejection amount is fixed to a predetermined value, the flushing with an appropriate ejection amount with respect to the actual internal temperature of the liquid ejection head The operation can be performed by the liquid ejecting head.

  In a preferred aspect of the present invention, the control unit causes the cleaning operation to discharge the liquid by suction or pressurization to the liquid ejecting head as the cooling operation, and sets the amount of liquid discharged by the cleaning operation according to the estimated temperature. . In the above aspect, since the liquid ejecting head is instructed to perform the cleaning operation for discharging the liquid by suction or pressurization to the liquid ejecting head, the internal temperature of the liquid ejecting head is effectively reduced by the flow and discharge of the heated liquid. It is possible to make it. In addition, since the discharge amount due to the cleaning operation is set according to the estimated temperature, cleaning with an appropriate discharge amount with respect to the actual internal temperature of the liquid ejecting head as compared with the configuration in which the discharge amount is fixed to a predetermined value. The operation can be performed by the liquid ejecting head.

  In a preferred aspect of the present invention, the control unit waits for liquid ejection, flushing operation for ejecting liquid by driving the drive element by supplying a drive signal, and liquid by suction or pressurization to the liquid ejection head. And a plurality of types of cooling operations including a cleaning operation for discharging water. In the above aspect, since a plurality of types of cooling operations including the standby operation, the flushing operation, and the cleaning operation are selectively performed, the liquid jet head is actually compared with a configuration in which only one type of cooling operation is performed. It is possible to execute an appropriate cooling operation with respect to the internal temperature.

  In a preferred aspect of the present invention, the control unit selects one of a plurality of types of cooling operations according to the difference between the estimated temperature and the reference temperature. In the above aspect, since a plurality of types of cooling operations are selectively executed according to the difference between the estimated temperature and the reference temperature, an appropriate cooling operation that can bring the internal temperature of the liquid ejecting head closer to the reference temperature is performed. There is an advantage that it can be selected.

  In a preferred aspect of the present invention, the control unit selects the standby operation when the difference between the estimated temperature and the reference temperature is below the first threshold value, and the difference is below the second threshold value that exceeds the first threshold value. A flushing operation is selected, and if the difference exceeds the second threshold, a cleaning operation is selected. In the above aspect, the standby operation is selected when the difference between the estimated temperature and the reference temperature is lower than the first threshold, the flushing operation is selected when the difference is lower than the second threshold, and the difference is the second threshold. Since the cleaning operation is selected when the value exceeds the value, it is possible to achieve both a decrease in the internal temperature T of the liquid ejecting head and a reduction in liquid consumption.

  A control method according to a preferred aspect of the present invention is a control method for a liquid ejecting head that ejects liquid by causing a drive element to vary the pressure in a pressure chamber filled with liquid according to a drive signal. The estimated temperature in the liquid ejecting head is identified from the residual vibration in the pressure chamber when the drive signal is supplied to and the cooling operation for lowering the temperature in the liquid ejecting head is performed at the estimated temperature identified by the estimating unit. And a step to be executed accordingly. In the above aspect, since the estimated temperature in the liquid ejecting head is specified from the residual vibration in the pressure chamber, the liquid ejecting head of the liquid ejecting head is compared with the technique of Patent Document 1 that detects the temperature at the supply port or the discharge port, for example. It is possible to estimate the internal temperature appropriately.

  A control device according to a preferred aspect of the present invention is a control device for a liquid ejecting head that ejects liquid by causing a drive element to vary the pressure in a pressure chamber filled with liquid according to a drive signal. The estimation unit that identifies the estimated temperature in the liquid ejecting head from the residual vibration in the pressure chamber when the drive signal is supplied to and the estimated temperature that the estimating unit identifies the cooling operation for reducing the temperature in the liquid ejecting head And a control unit to be executed according to the above. In the above aspect, since the estimated temperature in the liquid ejecting head is specified from the residual vibration in the pressure chamber, the liquid ejecting head of the liquid ejecting head is compared with the technique of Patent Document 1 that detects the temperature at the supply port or the discharge port, for example. It is possible to estimate the internal temperature appropriately.

1 is a configuration diagram of a liquid ejecting apparatus according to a first embodiment of the invention. It is a block diagram which paid its attention to the function of a liquid ejecting apparatus. It is explanatory drawing of a drive signal and a residual vibration. It is sectional drawing of an ejection head part. It is explanatory drawing of a conversion table. 6 is a graph of a standby time necessary for eliminating a temperature rise in the liquid ejecting head. It is a flowchart of operation | movement of a control part. It is a flowchart of operation | movement of the control part in 2nd Embodiment. 6 is a graph of an ejection amount necessary for eliminating a temperature rise in a liquid ejecting head by a flushing operation. FIG. 10 is a configuration diagram of a liquid ejecting apparatus according to a third embodiment. It is a flowchart of operation | movement of the control part of 3rd Embodiment. It is a flowchart of the operation | movement of control in 4th Embodiment.

<First Embodiment>
FIG. 1 is a configuration diagram illustrating a liquid ejecting apparatus 100 according to the first embodiment of the invention. The liquid ejecting apparatus 100 according to the first embodiment is an ink jet printing apparatus that ejects ink, which is an example of a liquid, onto the medium 12. The medium 12 is typically printing paper, but any print target such as a resin film or fabric can be used as the medium 12. As illustrated in FIG. 1, a liquid container 14 that stores ink is fixed to the liquid ejecting apparatus 100. For example, a cartridge that can be attached to and detached from the liquid ejecting apparatus 100, a bag-shaped ink pack formed of a flexible film, or an ink tank that can be refilled with ink is used as the liquid container 14. A plurality of types of inks having different colors are stored in the liquid container 14.

  As illustrated in FIG. 1, the liquid ejecting apparatus 100 includes a control unit 20, a transport mechanism 22, a moving mechanism 24, and a liquid ejecting head 26. The control unit 20 is a control device that includes a processing circuit 202 such as a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) and a storage circuit 204 such as a semiconductor memory, and controls stored in the storage circuit 204. By executing the program by the processing circuit 202, each element of the liquid ejecting apparatus 100 is comprehensively controlled. Image data G representing an image to be formed on the medium 12 is supplied to the control unit 20 from an external device (not shown) such as a host computer. The control unit 20 controls each element of the liquid ejecting apparatus 100 so that an image specified by the image data G is formed on the medium 12.

  The transport mechanism 22 transports the medium 12 in the Y direction under the control of the control unit 20. The moving mechanism 24 reciprocates the liquid jet head 26 in the X direction under the control of the control unit 20. The X direction is a direction that intersects (typically orthogonal) the Y direction in which the medium 12 is conveyed. The moving mechanism 24 of the first embodiment includes a substantially box-shaped transport body (carriage) 242 that houses the liquid jet head 26 and an endless belt 244 in the X direction to which the transport body 242 is fixed. The liquid ejecting head 26 ejects ink supplied from the liquid container 14 to the medium 12 from a plurality of nozzles (ejection holes) under the control of the control unit 20. In parallel with the transport of the medium 12 by the transport mechanism 22 and the reciprocating reciprocation of the transport body 242, the liquid ejecting head 26 ejects ink onto the medium 12, thereby forming a desired image on the surface of the medium 12. Note that the liquid container 14 can be mounted on the transport body 242 together with the liquid ejecting head 26.

  FIG. 2 is a configuration diagram that focuses on the function of the liquid ejecting apparatus 100. Illustration of the transport mechanism 22, the moving mechanism 24, etc. is omitted for convenience. As illustrated in FIG. 2, the control unit 20 of the first embodiment functions as the control unit 32 and the estimation unit 34 when the processing circuit 202 executes the control program stored in the storage circuit 204. The control unit 32 controls the liquid ejecting head 26. The control unit 32 according to the first embodiment generates the drive signal COM and the print signal SI and supplies them to the liquid ejecting head 26. As illustrated in FIG. 3, the drive signal COM is a signal including a drive pulse P every predetermined period. The specific waveform of the drive pulse P is arbitrary. Further, a configuration including a plurality of drive pulses P in one cycle of the drive signal COM or a configuration using a plurality of drive signals COM having different waveforms may be employed. The print signal SI is a signal for instructing, for each nozzle, whether or not ink is ejected by the liquid ejecting head 26, and is generated according to image data G supplied from an external device. 2 estimates a temperature E (hereinafter referred to as “estimated temperature”) E inside the liquid jet head 26.

  As illustrated in FIG. 2, the liquid jet head 26 according to the first embodiment includes a drive unit 42, a jet head unit 44, and a detection unit 46. The drive unit 42 is a drive circuit that drives the ejection head unit 44 under the control of the control unit 20. The ejection head unit 44 ejects ink supplied from the liquid container 14 to the medium 12 from a plurality of nozzles. The ejection head unit 44 of the first embodiment includes a plurality of ejection units 440 corresponding to different nozzles. Each of the plurality of ejection units 440 ejects ink according to the drive signal D supplied from the drive unit 42.

  The drive unit 42 generates a drive signal D corresponding to the drive signal COM and the print signal SI for each ejection unit 440 and outputs the drive signal D to the plurality of ejection units 440 in parallel. Specifically, the drive unit 42 supplies the drive pulse P of the drive signal COM as the drive signal D to the ejection unit 440 in which the print signal SI instructs the ejection of ink among the plurality of ejection units 440, and the print signal SI. Supplies a drive signal D having a predetermined reference voltage to the ejection unit 440 that instructs non-ejection of ink.

  FIG. 4 is a cross-sectional view of the ejection head unit 44 focusing on one arbitrary ejection unit 440. As illustrated in FIG. 4, in the ejection head unit 44, the pressure chamber substrate 72, the vibration plate 73, and the piezoelectric element 74 support body 75 are disposed on one side of the flow path substrate 71, and the nozzle plate 76 is disposed on the other side. Arranged structure. The flow path substrate 71, the pressure chamber substrate 72, and the nozzle plate 76 are formed of, for example, a silicon flat plate material, and the support body 75 is formed of, for example, an injection molding of a resin material. As illustrated in FIG. 4, a plurality of nozzles N are formed on the nozzle plate 76. It is also possible to arrange a plurality of nozzles N in a plurality of rows (for example, a staggered arrangement or a staggered arrangement).

  In the flow path substrate 71, an opening 712, a branch flow path (restricted flow path) 714, and a communication flow path 716 are formed. The branch flow path 714 and the communication flow path 716 are through holes formed for each nozzle N, and the opening 712 is an opening continuous over a plurality of nozzles N. A space in which the accommodating portion (concave portion) 752 formed in the support body 752 and the opening 712 of the flow path substrate 71 communicate with each other is supplied from the liquid container 14 via the introduction flow path 754 of the support body 75. It functions as a common liquid chamber (reservoir) R for storing ink.

  An opening 722 is formed for each nozzle N in the pressure chamber substrate 72. The vibration plate 73 is an elastically deformable flat plate that is installed on the surface of the pressure chamber substrate 72 opposite to the flow path substrate 71. A space sandwiched between the diaphragm 73 and the flow path substrate 71 inside each opening 722 of the pressure chamber substrate 72 is a pressure chamber filled with ink supplied from the common liquid chamber R via the branch flow path 714. (Cavity) Functions as C. Each pressure chamber C communicates with the nozzle N via the communication channel 716 of the channel substrate 71.

  A piezoelectric element 74 is formed for each nozzle N on the surface of the diaphragm 73 opposite to the pressure chamber substrate 72. Each piezoelectric element 74 is a drive element in which a piezoelectric body is interposed between electrodes facing each other. When the diaphragm 73 is vibrated by the deformation of the piezoelectric element 74 by the supply of the drive pulse P of the drive signal D, the pressure in the pressure chamber C varies and the ink in the pressure chamber C is ejected from the nozzle N. One injection unit 440 illustrated in FIG. 3 is a part including the piezoelectric element 74, the diaphragm 73, the pressure chamber C, and the nozzle N.

  As illustrated in FIG. 3, when the piezoelectric element 74 is driven by supplying the drive signal D, the pressure fluctuation (hereinafter referred to as “residual vibration”) V caused by the vibration of the ink in the pressure chamber C or the like becomes the drive pulse P. Continue after the supply. The residual vibration V can also be restated as vibration of the diaphragm 73 that continues after the drive pulse P is supplied. The detection unit 46 in FIG. 2 detects the residual vibration V in the pressure chamber C when the drive signal D is supplied to the piezoelectric element 74 for each of the plurality of injection units 440. Specifically, the detection unit 46 of the first embodiment detects a variation in the electromotive force of the piezoelectric element 74 over a predetermined time after the supply of the drive pulse P as a residual vibration V and a detection signal representing the residual vibration V. Generate DV. In the above description, the configuration in which the drive unit 42 and the detection unit 46 are mounted on the liquid ejecting head 26 is illustrated, but one or both of the drive unit 42 and the detection unit 46 can be mounted on the control unit 20. is there. One or both of the drive unit 42 and the detection unit 46 can be installed on a wiring board (not shown) interposed between the control unit 20 and the liquid jet head 26.

  The characteristic of the residual vibration V depends on the internal temperature T of the liquid ejecting head 26 (and the viscosity of the ink corresponding to the internal temperature T). In consideration of the above tendency, the estimation unit 34 in FIG. 2 specifies the estimated temperature E of the liquid jet head 26 from the residual vibration V detected by the detection unit 46. Specifically, the estimation unit 34 of the first embodiment analyzes the characteristic value F that depends on the estimated temperature E for the residual vibration V, and specifies the estimated temperature E from the characteristic value F.

  For example, the relative ratio of the peak values of the peaks that follow each other in the residual vibration V (for example, the ratio h2 / h1 of the peak value h2 to the peak value h1 as illustrated in FIG. 3) is calculated as the characteristic value F. Assuming a relationship in which the viscosity of the ink increases and the residual vibration V easily attenuates as the internal temperature T of the liquid ejecting head 26 decreases, the characteristic value F decreases as the internal temperature T decreases (the ink viscosity increases). Numerical value. Further, assuming the above-described relationship that the residual vibration V is more easily attenuated as the internal temperature T of the liquid ejecting head 26 is lower, the internal temperature of the liquid ejecting head 26 is calculated by calculating the period of the residual vibration V as the characteristic value F. The lower the T (the higher the viscosity of the ink), the larger the characteristic value F becomes. As understood from the above description, the characteristic value F corresponds to an index of the viscosity of the ink existing inside the liquid ejecting head 26.

  For example, the conversion table B of FIG. 5 stored in advance in the storage circuit 204 is used to specify the estimated temperature E according to the characteristic value F. As illustrated in FIG. 5, the conversion table B is a data table that correlates each numerical value of the characteristic value F (F1, F2,...) And each numerical value of the estimated temperature E (E1, E2,...). is there. The estimation unit 34 searches the conversion table B for the estimated temperature E corresponding to the characteristic value F of the residual vibration V. It is also possible to specify the estimated temperature E by a predetermined calculation using the characteristic value F.

  The control unit 32 according to the first embodiment performs an operation for reducing the internal temperature T of the liquid ejecting head 26 (hereinafter referred to as “cooling operation”) according to the estimated temperature E specified by the estimation unit 34. The cooling operation of the first embodiment is a standby operation for waiting for ink ejection by the liquid ejecting head 26. Specifically, a configuration in which a standby operation is performed between the forward movement (movement to one side in the X direction) and the backward movement (movement to the other side in the X direction) of the transport body 242, or a plurality of media 12. In contrast, a configuration may be employed in which a standby operation is performed during the conveyance of the successive media 12 in a situation where ink is sequentially ejected. The internal temperature T of the liquid ejecting head 26 decreases due to natural heat dissipation during execution of the standby operation.

  FIG. 6 shows the amount of increase ΔT (ΔT = T−T0) of the internal temperature T of the liquid ejecting head 26 with respect to a predetermined reference temperature T0 and the length of time of standby operation necessary to eliminate the increase in the internal temperature T (hereinafter referred to as “the amount of internal temperature T”). It is a graph showing a relationship with W) (referred to as “waiting time”). The reference temperature T0 is, for example, a temperature at which the ink viscosity becomes a desired design value, or a temperature at the time when the power of the liquid ejecting apparatus 100 is turned on, for example. As understood from FIG. 6, the larger the increase amount ΔT of the internal temperature T, the longer the standby time W for eliminating the temperature increase of the increase amount ΔT by natural heat dissipation. In consideration of the above tendency, the control unit 32 of the first embodiment variably sets the standby time W for causing the liquid ejecting head 26 to perform the standby operation according to the estimated temperature E. Specifically, the waiting time W is variably set according to a difference (hereinafter referred to as “estimated increase amount”) ΔE (ΔE = E−T0) between the estimated temperature E and the reference temperature T0. For example, considering the tendency of FIG. 6, the standby time W is set to a longer time as the estimated increase amount ΔE is larger.

  FIG. 7 is a flowchart of a process in which the control unit 20 of the first embodiment controls the liquid ejecting head 26 (that is, a method for controlling the liquid ejecting head 26). For example, the process of FIG. 7 is executed at predetermined time intervals. When the processing of FIG. 7 is started, the estimation unit 34 acquires a detection signal DV representing the residual vibration V in the pressure chamber C when the drive signal D is supplied to the piezoelectric element 74 from the detection unit 46 (SA1). Then, the estimation unit 34 specifies the estimated temperature E in the liquid ejecting head 26 by analyzing the residual vibration V represented by the detection signal DV (SA2). For specifying the estimated temperature E, the conversion table B of FIG. 5 is used.

  The control unit 32 determines whether or not the estimated temperature E estimated by the estimation unit 34 exceeds a predetermined threshold value ETH (SA3). The threshold value ETH is set to a predetermined value that exceeds the reference temperature T0, for example. When the estimated temperature E exceeds the threshold value ETH (SA3: YES), the control unit 32 sets the standby time W according to the estimated temperature E (SA4). Then, the control unit 32 causes the liquid jet head 26 to execute a standby operation over the standby time W (SA5). The liquid ejecting head 26 waits for ink ejection over a waiting time W in accordance with an instruction from the control unit 32. On the other hand, when the estimated temperature E is lower than the threshold value ETH (SA3: NO), the setting of the standby time W (SA4) and the standby operation instruction (SA5) are not executed.

  As described above, in the first embodiment, the estimated temperature E in the liquid ejecting head 26 is specified from the residual vibration V in the pressure chamber C. Therefore, there is an advantage that the actual internal temperature T of the liquid ejecting head 26 can be estimated with high accuracy, for example, compared with the technique of Patent Document 1 in which the temperature is detected at the supply port or the discharge port. Further, since the cooling operation is instructed to the liquid ejecting head 26 according to the estimated temperature E specified by the estimating unit 34, an appropriate cooling operation is performed on the liquid ejecting head 26 with respect to the actual internal temperature T of the liquid ejecting head 26. It is possible to execute.

  In the first embodiment, in particular, the standby operation for waiting for ink ejection is instructed to the liquid ejecting head 26 as a cooling operation. Therefore, compared to the configuration in which the internal temperature T of the liquid ejecting head 26 is decreased by discharging ink, There is an advantage that the internal temperature T of the liquid ejecting head 26 can be lowered without consuming ink. Further, since the standby time W is set according to the estimated temperature E, an appropriate standby time with respect to the actual internal temperature T of the liquid ejecting head 26 as compared with the configuration in which the standby time W is fixed to a predetermined value. It is possible to cause the liquid ejecting head 26 to execute the standby operation over W.

Second Embodiment
A second embodiment of the present invention will be described. In addition, about the element which an effect | action and function are the same as that of 1st Embodiment in each form illustrated below, the reference | standard referred by description of 1st Embodiment is diverted, and each detailed description is abbreviate | omitted suitably.

  In the first embodiment, the standby operation over the standby time W is exemplified as the cooling operation. The control unit 32 according to the second embodiment causes the liquid ejecting head 26 to execute a flushing operation of ejecting ink by driving the piezoelectric element 74 by supplying the drive signal D as a cooling operation. The flushing operation is an operation in which, for example, the liquid ejecting head 26 that has moved to a standby position that does not face the medium 12 (for example, an end of a range in which the conveyance body 242 reciprocates) ejects ink from the plurality of nozzles N. The inside of the liquid ejecting head 26 is cooled by discharging high temperature ink by the flushing operation by the liquid ejecting head 26. The operation in which the detection unit 46 detects the residual vibration V and the operation in which the estimation unit 34 specifies the estimated temperature E of the liquid ejecting head 26 from the detection signal DV (residual vibration V) are the same as in the first embodiment. Accordingly, as in the first embodiment, it is possible to estimate the actual internal temperature T of the liquid ejecting head 26 with high accuracy and cause the liquid ejecting head 26 to perform an appropriate cooling operation.

  The control unit 32 of the second embodiment executes the process of FIG. 8 instead of the process of FIG. 7 illustrated in the first embodiment. As in the first embodiment, when the estimation unit 34 executes acquisition of the detection signal DV (SB1) and specification of the estimated temperature E (SB2), the control unit 32 determines whether or not the estimated temperature E exceeds the threshold value ETH. Is determined (SB3). When the estimated temperature E exceeds the threshold value ETH (SB3: YES), the control unit 32 variably sets the ink ejection amount MA to be ejected by the liquid ejecting head 26 in the flushing operation according to the estimated temperature E (SB4). .

  FIG. 9 shows the relationship between the increase amount ΔT (ΔT = T−T0) of the internal temperature T of the liquid ejecting head 26 and the ink injection amount MA necessary for eliminating the increase in the internal temperature T by the flushing operation. It is a graph. As can be understood from FIG. 9, the larger the increase amount ΔT of the internal temperature T, the greater the ink ejection amount MA necessary to eliminate the temperature increase of the increase amount ΔT. Considering the above tendency, the control unit 32 of the second embodiment sets the ink ejection amount MA due to the flushing operation of the liquid ejection head 26 to the estimated increase amount ΔE (which is the difference between the estimated temperature E and the reference temperature T0. ΔE = E−T0). For example, considering the tendency of FIG. 9, the larger the estimated increase amount ΔE, the larger the injection amount MA is set.

  The control unit 32 causes the liquid ejecting head 26 to perform a flushing operation for ejecting ink of the ejection amount MA (SB5). The liquid ejecting head 26 performs a flushing operation for the ejection amount MA in accordance with an instruction from the control unit 32. On the other hand, when the estimated temperature E is lower than the threshold value ETH (SB3: NO), the setting of the injection amount MA (SB4) and the instruction for the flushing operation (SB5) are not executed.

  Also in the second embodiment, since the cooling operation (flushing operation) is instructed to the liquid ejecting head 26 according to the estimated temperature E, the actual internal temperature T of the liquid ejecting head 26 with respect to the actual internal temperature T as in the first embodiment. Thus, it is possible to cause the liquid ejecting head 26 to perform an appropriate cooling operation. In the second embodiment, in particular, the flushing operation for ejecting ink is instructed to the liquid ejecting head 26 by driving the piezoelectric element 74, so that the internal temperature T of the liquid ejecting head 26 is effectively controlled by the flow and ejection of heated ink. Can be reduced. Further, since the ejection amount MA by the flushing operation is set according to the estimated temperature E, the ejection amount MA is appropriate for the actual internal temperature T of the liquid ejection head 26 as compared with the configuration in which the ejection amount MA is fixed to a predetermined value. It is possible to cause the liquid ejecting head 26 to perform a flushing operation with a proper ejection amount MA.

<Third Embodiment>
FIG. 10 is a configuration diagram illustrating the liquid ejecting apparatus 100 according to the third embodiment. As illustrated in FIG. 10, the liquid ejecting apparatus 100 according to the third embodiment has a configuration in which a discharge mechanism 28 is added to the first embodiment. The discharge mechanism 28 is a mechanism that executes a cleaning operation for forcibly discharging the ink inside the liquid ejecting head 26. As the high temperature ink is discharged from the liquid ejecting head 26 by the cleaning operation, the inside of the liquid ejecting head 26 is cooled. That is, the cleaning operation is an example of a cooling operation for reducing the temperature in the liquid ejecting head 26.

  Specifically, the discharge mechanism 28 sucks the inside of the cap member that seals the ejection surface (the surface facing the medium 12) on which the plurality of nozzles N are formed in the liquid ejection head 26, for example. Including a pump. The ink inside the liquid ejecting head 26 is forcibly discharged to the inside of the cap member through the plurality of nozzles N by the cleaning operation of sucking the inside with the sealing surface sealed by the cap member. The operation of detecting the residual vibration V by the detection unit 46 and the operation of specifying the estimated temperature E from the detection signal DV (residual vibration V) by the estimation unit 34 are the same as in the first embodiment. Accordingly, as in the first embodiment, it is possible to estimate the actual internal temperature T of the liquid ejecting head 26 with high accuracy and cause the liquid ejecting head 26 to perform an appropriate cooling operation.

  The control unit 32 of the third embodiment executes the process of FIG. 11 instead of the process of FIG. 6 illustrated in the first embodiment. As in the first embodiment, when the estimation unit 34 executes acquisition of the detection signal DV (SC1) and specification of the estimated temperature E (SC2), the control unit 32 determines whether or not the estimated temperature E exceeds the threshold value ETH. (SC3) When the estimated temperature E exceeds the threshold value ETH (SC3: YES), the control unit 32 varies the ink discharge amount MB to be discharged from the liquid ejecting head 26 by the cleaning operation in accordance with the estimated temperature E. (SC4). There is a tendency that as the increase amount ΔT of the internal temperature T is larger, the ink discharge amount MB required to eliminate the temperature increase of the increase amount ΔT increases. Considering the above tendency, the control unit 32 of the third embodiment sets the ink discharge amount MB due to the cleaning operation by the discharge mechanism 28 to the estimated increase amount ΔE (ΔE) which is the difference between the estimated temperature E and the reference temperature T0. = E-T0). Specifically, the larger the estimated increase amount ΔE, the larger the discharge amount MB is set.

  The controller 32 causes the discharge mechanism 28 to execute a cleaning operation for discharging the ink of the discharge amount MB (SC5). The discharge mechanism 28 executes a cleaning operation for the discharge amount MB in accordance with an instruction from the control unit 32. On the other hand, when the estimated temperature E is lower than the threshold value ETH (SC3: NO), the discharge amount MB setting (SC4) and the cleaning operation instruction (SC5) are not executed.

  Also in the third embodiment, since a cooling operation (flushing operation) is instructed according to the estimated temperature E, an appropriate cooling operation with respect to the actual internal temperature T of the liquid jet head 26 as in the first embodiment. Can be executed by the liquid ejecting head 26. In the third embodiment, in particular, since the liquid ejecting head 26 is instructed to perform a cleaning operation for ejecting ink by suction or pressurization with respect to the liquid ejecting head 26, the internal temperature of the liquid ejecting head 26 is determined by the flow and discharge of heated ink. T can be effectively reduced. Further, since the discharge amount MB due to the cleaning operation is set according to the estimated temperature E, the discharge amount MB is more appropriate for the actual internal temperature T of the liquid ejecting head 26 than the configuration in which the discharge amount MB is fixed to a predetermined value. It is possible to cause the liquid ejecting head 26 to perform a cleaning operation with a proper discharge amount MB.

<Fourth embodiment>
The ink consumption and the cooling performance of the liquid ejecting head 26 in the cooling operation exemplified in the first to third embodiments will be examined. In the standby operation of the first embodiment, it is not necessary to eject ink by the liquid ejecting head 26. Further, the ink ejection amount MA by the flushing operation exemplified in the second embodiment is lower than the ink discharge amount MB by the cleaning operation exemplified in the third embodiment. On the other hand, the cooling performance of the cleaning operation for discharging a large amount of ink exceeds the cooling performance of the flushing operation, and the cooling performance of the standby operation is lower than the cooling performance of the flushing operation or cleaning operation for discharging ink. As understood from the above description, the cooling performance by the cooling operation and the ink consumption are roughly in a trade-off relationship.

  Considering the above tendency, the control unit 32 of the fourth embodiment selectively performs the standby operation, the flushing operation, and the cleaning operation as the cooling operation. For example, in a situation where the estimated temperature E is close to the reference temperature T0, the cooling performance is not so required. Therefore, the standby operation is more advantageous than the flushing operation and the cleaning operation from the viewpoint of suppressing ink consumption. On the other hand, in a situation where the estimated temperature E is sufficiently higher than the reference temperature T0, the cooling performance should be sufficiently ensured even if the ink consumption is allowed, so the flushing operation and the cleaning operation (especially the cleaning operation) are on standby. It is advantageous compared to operation. In consideration of the above tendency, the control unit 32 of the fourth embodiment selects any one of the standby operation, the flushing operation, and the cleaning operation in accordance with the estimated increase amount ΔE that is the difference between the estimated temperature E and the reference temperature T0. Select.

  The control unit 32 of the fourth embodiment executes the process of FIG. 12 instead of the process of FIG. 6 illustrated in the first embodiment. As in the first embodiment, the estimation unit 34 acquires the detection signal DV from the detection unit 46 (SD1), and specifies the estimated temperature E of the liquid ejecting head 26 from the residual vibration V represented by the detection signal DV (SD2). ). Then, the estimating unit 34 calculates the difference between the estimated temperature E and the predetermined reference temperature T0 as the estimated increase amount ΔE (ΔE = E−T0) (SD3).

  The control unit 32 determines whether or not the estimated increase amount ΔE exceeds the threshold value TH0 (SD4). When the estimated increase amount ΔE exceeds the threshold value TH0 (SD4: YES), the control unit 32 determines whether or not the estimated increase amount ΔE is less than the threshold value TH1 (SD5). The threshold value TH1 is set to a predetermined value that exceeds the threshold value TH0 (TH1> TH0). When the estimated increase amount ΔE is lower than the threshold value TH1 (SD5: YES, TH0 <ΔE <TH1), the control unit 32 sets the standby time W according to the estimated temperature E as in the first embodiment ( SD6) The liquid ejecting head 26 is caused to perform a standby operation over the standby time W (SD7).

  On the other hand, when the estimated increase amount ΔE exceeds the threshold value TH1 (SD5: NO), the control unit 32 determines whether or not the estimated increase amount ΔE is less than the threshold value TH2 (SD8). The threshold value TH2 is set to a predetermined value that exceeds the threshold value TH1 (TH2> TH1). When the estimated increase amount ΔE is lower than the threshold value TH2 (SD8: YES, TH1 <ΔE <TH2), the control unit 32 sets the injection amount MA according to the estimated temperature E as in the second embodiment ( SD9), the liquid ejecting head 26 is caused to perform the flushing operation of the ejection amount MA (SD10). On the other hand, when the estimated increase amount ΔE exceeds the threshold value TH2 (SD8: NO, ΔE> TH2), the control unit 32 sets the discharge amount MB according to the estimated temperature E, as in the third embodiment ( SD11), the discharge mechanism 28 is caused to execute a cleaning operation for discharging the discharge amount MB of ink (SD12). When the estimated increase amount ΔE is less than the threshold value TH0 (SD4: NO), the operation exemplified above (SD4-SD12) is not executed.

  As described above, in the fourth embodiment, since a plurality of cooling operations including a standby operation, a flushing operation, and a cleaning operation are selectively performed, compared to a configuration in which only one type of cooling operation is performed. An appropriate cooling operation can be performed on the actual internal temperature T of the liquid jet head 26. Further, since the cooling operation is selected according to the difference (estimated increase ΔE) between the estimated temperature E and the reference temperature T0, appropriate cooling that can bring the internal temperature T of the liquid jet head 26 close to the reference temperature T0. It is possible to select an action. Particularly in the fourth embodiment, the standby operation is selected when the estimated increase amount ΔE is less than the threshold value TH1 (SD5: YES), and the flushing operation is selected when the estimated increase amount ΔE is less than the threshold value TH2 (SD8: YES). When the estimated increase amount ΔE exceeds the threshold value TH2 (SD8: NO), the cleaning operation is selected. Accordingly, it is possible to achieve both a reduction in the internal temperature T of the liquid ejecting head 26 and a reduction in ink consumption at a high level.

<Modification>
Each form illustrated above can be variously modified. Specific modifications are exemplified below. Two or more aspects arbitrarily selected from the following examples can be appropriately combined as long as they do not contradict each other.

(1) In the cleaning operation of the third embodiment and the fourth embodiment, the ink is discharged by suction from the downstream side (nozzle N) of the liquid ejecting head 26, but the specific method of the cleaning operation is exemplified above. It is not limited. For example, the ink is discharged by both a cleaning operation for discharging ink from a plurality of nozzles by pressurization from the upstream side (liquid container 14 side) of the liquid ejecting head 26, and pressurization from the upstream side and suction from the downstream side. It is also possible for the discharging mechanism 28 to execute the cleaning operation for discharging.

(2) In the fourth embodiment, the case where the standby operation, the flushing operation, and the cleaning operation are selected is exemplified. However, the control unit 32 selects two of the three types of cooling operations exemplified above as candidates. It is also possible.

(3) The specific contents of the cooling operation for lowering the temperature in the liquid ejecting head 26 are not limited to the above-described examples (standby operation, flushing operation, cleaning operation). For example, the control unit 32 can execute the operation of operating the air blowing fan to cool the liquid ejecting head 26 as a cooling operation.

(4) The element (driving element) that applies pressure to the inside of the pressure chamber C is not limited to the piezoelectric element 74 exemplified in the above-described embodiments. For example, a heating element that generates bubbles in the pressure chamber C by heating to change the pressure can be used as the driving element. As understood from the above examples, the drive element is comprehensively expressed as an element for ejecting liquid (typically, an element that applies pressure to the inside of the pressure chamber C), and an operation method (piezoelectric method / The heat system) and the specific configuration are not questioned.

(5) In each of the above-described embodiments, the serial type liquid ejecting apparatus 100 that moves the transport body 242 on which the liquid ejecting head 26 is mounted in the X direction is illustrated. However, the plurality of nozzles N of the liquid ejecting head 26 are the medium 12. The present invention can also be applied to a line-type liquid ejecting apparatus distributed over the entire width.

(6) The liquid ejecting apparatus 100 exemplified in each of the above-described embodiments can be employed in various apparatuses such as a facsimile apparatus and a copying machine in addition to apparatuses dedicated to printing. However, the use of the liquid ejecting apparatus of the present invention is not limited to printing. For example, a liquid ejecting apparatus that ejects a solution of a coloring material is used as a manufacturing apparatus that forms a color filter of a liquid crystal display device. Further, a liquid ejecting apparatus that ejects a solution of a conductive material is used as a manufacturing apparatus that forms wiring and electrodes of a wiring board.

(7) The control unit 20 exemplified in the above embodiments can be realized by the cooperation of the processing circuit 202 (computer) and a control program. As understood from the examples of the above-described embodiments, the control program according to a preferred aspect ejects ink by causing the piezoelectric element 74 to vary the pressure in the pressure chamber C filled with ink according to the drive signal D. A program for controlling the liquid ejecting head 26, and the computer (for example, the processing circuit 202) causes the residual vibration V in the pressure chamber C when the drive signal D is supplied to the piezoelectric element 74 to be generated in the liquid ejecting head 26. The estimation unit 34 for specifying the estimated temperature E and the cooling unit 32 for causing the cooling operation for reducing the internal temperature T of the liquid jet head 26 to function according to the estimated temperature E specified by the estimation unit 34 are caused to function. . The control program exemplified above can be provided in a form stored in a computer-readable recording medium and installed in the computer. The recording medium is, for example, a non-transitory recording medium, and an optical recording medium (optical disk) such as a CD-ROM is a good example, but a known arbitrary one such as a semiconductor recording medium or a magnetic recording medium This type of recording medium can be included. It is also possible to distribute the control program to a computer in the form of distribution via a communication network.

DESCRIPTION OF SYMBOLS 100 ... Liquid ejecting apparatus, 12 ... Medium, 14 ... Liquid container, 20 ... Control unit (control apparatus), 202 ... Processing circuit, 204 ... Memory circuit, 22 ... Conveying mechanism, 24 ... Moving mechanism, 26 ... Liquid ejecting head, DESCRIPTION OF SYMBOLS 28 ... Discharge mechanism, 32 ... Control part, 34 ... Estimation part, 42 ... Drive part, 44 ... Injection head part, 440 ... Injection part, 46 ... Detection part.

Claims (9)

A liquid ejecting head that ejects the liquid by causing the driving element to vary the pressure in the pressure chamber filled with the liquid according to a driving signal;
A detection unit for detecting residual vibration in the pressure chamber when a driving signal is supplied to the driving element;
An estimation unit that identifies an estimated temperature in the liquid jet head from the residual vibration detected by the detection unit;
A liquid ejecting apparatus comprising: a control unit that executes a cooling operation for lowering the temperature in the liquid ejecting head according to the estimated temperature specified by the estimating unit. The liquid ejecting apparatus according to claim 1, wherein the control unit causes the liquid ejecting head to execute a standby operation for waiting for the ejection of the liquid as the cooling operation, and sets a standby time for the standby operation according to the estimated temperature. The control unit causes the liquid ejecting head to perform a flushing operation for ejecting the liquid by driving the drive element by supplying the drive signal as the cooling operation, and determines an ejection amount of the liquid by the flushing operation as the estimated temperature. The liquid ejecting apparatus according to claim 1, wherein the liquid ejecting apparatus is set according to. The control unit causes a cleaning operation for discharging the liquid by suction or pressurization to the liquid ejecting head to be executed as the cooling operation, and sets an amount of the liquid discharged by the cleaning operation according to the estimated temperature. The liquid ejecting apparatus according to claim 1. The control unit is configured to wait for the liquid to be ejected, to perform a flushing operation to eject the liquid by driving the driving element by supplying the driving signal, and to suck the liquid by suction or pressurization to the liquid ejecting head. The liquid ejecting apparatus according to claim 1, wherein a plurality of types of cooling operations including a discharging operation are selectively performed. The liquid ejecting apparatus according to claim 5, wherein the control unit selects one of the plurality of types of cooling operations according to a difference between the estimated temperature and a reference temperature. The control unit selects the standby operation when the difference between the estimated temperature and the reference temperature falls below a first threshold, and the flushing operation when the difference falls below a second threshold that exceeds the first threshold. The liquid ejecting apparatus according to claim 6, wherein the cleaning operation is selected when the difference exceeds the second threshold value. A control method of a liquid ejecting head that ejects the liquid by causing a drive element to vary a pressure in a pressure chamber filled with liquid according to a drive signal,
Identifying an estimated temperature in the liquid jet head from residual vibration in the pressure chamber when a driving signal is supplied to the driving element;
And a step of performing a cooling operation for lowering the temperature in the liquid ejecting head in accordance with the estimated temperature specified by the estimating unit. A control device for a liquid ejecting head that ejects the liquid by causing a drive element to vary a pressure in a pressure chamber filled with the liquid according to a drive signal,
An estimation unit that identifies an estimated temperature in the liquid jet head from residual vibration in the pressure chamber when a driving signal is supplied to the driving element;
A control unit for a liquid ejecting head, comprising: a control unit that performs a cooling operation for lowering the temperature in the liquid ejecting head according to the estimated temperature specified by the estimating unit.

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