JP2016137606A - Liquid injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid injection device that can suppress a temperature of a nozzle in an injection part from excessively rising.SOLUTION: A liquid injection device 11 comprises: an injection part 14 that sprays ink to a continuous paper P; a heating part 15 that heats a liquid injection region RIL, a region where the injection part 14 can spray the ink to the continuous paper P; an IR sensor 29 that detects a temperature of the liquid injection region RIL; a nozzle plate thermistor 24 that detects a temperature of a surface opposing to the continuous paper P in the injection part 14; and a control part 30 that controls the heating part 15 on the basis of a first detection temperature detected by the IR sensor 29 and a second detection temperature of the nozzle plate thermistor 24.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid ejecting apparatus including a heating unit that heats a medium.

  Conventionally, as a kind of liquid ejecting apparatus, a liquid such as ink is ejected from a ejecting unit onto a medium such as continuous paper conveyed on a support member, and then the liquid is heated by a heating unit. Then, an ink jet printer that prints an image or the like on a medium by drying is known. In addition, as such a printer, a first temperature detection unit that detects the temperature of the medium, a second temperature detection unit that detects the temperature of the recording head substrate that can eject liquid from the nozzles in the ejection unit, and an infrared ray on the medium There is also a heating unit that radiates and controls the injection unit based on the detection temperature of the first temperature detection unit and the detection temperature of the second temperature detection unit (see, for example, Patent Document 1).

JP 2013-91263 A

  By the way, as the medium is heated by the heating unit, the temperature of the nozzle adjacent to the medium increases. As the nozzle temperature increases, the probability of ink clogging in the nozzle may increase. For this reason, when the temperature of the nozzle is high, it is necessary to frequently perform maintenance such as cleaning of the nozzle in order to avoid ink clogging of the nozzle.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid ejecting apparatus capable of suppressing an excessive increase in the temperature of a nozzle in an ejecting unit.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
A liquid ejecting apparatus that solves the above problems includes an ejecting unit that ejects a liquid onto a medium, a heating unit that heats a liquid ejecting region in which the ejecting unit can eject the liquid onto the medium, and the liquid A first temperature detection unit that detects a temperature of the ejection region; a second temperature detection unit that detects a temperature of a surface of the ejection unit that faces the medium and on which a nozzle is formed; and a first temperature detection unit A control unit that controls the heating unit based on one detection temperature and a second detection temperature of the second temperature detection unit.

  Since the nozzle of the ejection unit is close to the liquid ejection region in the medium, it is easily affected by the temperature of the liquid ejection region. For this reason, the temperature of the nozzle increases as the temperature of the medium increases. In this regard, according to this configuration, the heating unit is controlled in consideration of the second detection temperature that is the temperature of the surface of the ejection unit facing the medium. For this reason, when the 2nd detection temperature which is the temperature of a nozzle becomes high, for example, by making the output of a heating part small, the temperature rise of a nozzle can be suppressed by making the temperature of the liquid injection area | region in a medium low. . Therefore, it can suppress that the temperature of a nozzle becomes high too much.

  In the liquid ejecting apparatus, the control unit controls the heating unit so that the temperature of the medium becomes a reference target temperature when the second detected temperature is equal to or lower than a temperature threshold, while the second detected temperature is When the temperature threshold is exceeded, it is preferable to control the heating unit so that the first detected temperature is equal to or lower than the reference target temperature.

  In the liquid ejecting apparatus, the control unit controls the heating unit as the second detected temperature is higher than the temperature threshold and an integral value of a difference between the second detected temperature and the temperature threshold increases. It is preferable to lower the target temperature of the medium for the purpose.

  According to this configuration, the output of the heating unit decreases as the difference between the second detection temperature and the temperature threshold increases and as the period during which the second detection temperature is maintained higher than the temperature threshold increases. The temperature of the liquid ejecting area in the medium is lowered. For this reason, the temperature of the nozzle adjacent to the liquid ejecting region in the medium is unlikely to rise and is likely to fall.

  In the liquid ejecting apparatus, when the second detected temperature exceeds the temperature threshold, a corrected target temperature corrected so as to be lower than the reference target temperature is set as the target temperature of the medium for controlling the heating unit. And when the first detected temperature is equal to or lower than the corrected target temperature, the heating unit is controlled based on the reference target temperature, while when the first detected temperature is higher than the corrected target temperature, It is preferable to control the heating unit based on the corrected target temperature.

  When the temperature of the liquid ejecting area in the medium is low, the influence of the heat of the liquid ejecting area on the surface of the ejecting unit facing the liquid ejecting area is small, while the temperature of the liquid ejecting area needs to be quickly raised to the reference target temperature. is there. Further, when the temperature of the liquid ejecting area in the medium is high, the heat of the liquid ejecting area has a great influence on the surface of the ejecting unit facing the liquid ejecting area, while the temperature of the liquid ejecting area is close to the reference target temperature or the reference It is higher than the target temperature.

  Based on such matters, by controlling the heating unit as in the above configuration, the output of the heating unit is adjusted so as to achieve both the heating of the liquid jet region in the medium by the heating unit and the suppression of the temperature rise of the nozzle. Can be controlled.

In the liquid ejecting apparatus, it is preferable that the liquid ejecting apparatus further includes a blower for uniformizing the temperature of the medium.
According to this configuration, since the variation in the first detection temperature of the first temperature detection unit can be reduced, it is possible to suppress a decrease in the temperature detection accuracy of the liquid ejection region in the medium by the first temperature detection unit. .

1 is a schematic configuration diagram of an embodiment of a liquid ejecting apparatus. FIG. 2 is a schematic configuration diagram illustrating a front structure of the liquid ejecting apparatus of FIG. 1. FIG. 3 is a block diagram illustrating an electrical configuration of the liquid ejecting apparatus. 6 is a flowchart showing a procedure of output control executed by the liquid ejecting apparatus. The time chart which shows one execution aspect of a part of output control. The graph which shows the relationship between the calorie | heat amount DUTY value of a heating part, and the detection error of a 1st temperature detection part. The time chart which shows one execution aspect of a part of output control.

  Hereinafter, an embodiment of a liquid ejecting apparatus will be described with reference to the drawings. Note that the liquid ejecting apparatus according to the present embodiment includes, for example, an ink jet printer that performs printing by ejecting ink, which is an example of a liquid, onto a medium. The printer is a so-called serial printer that performs printing by moving the ejection unit in the scanning direction, which is the direction in which the printing method intersects the conveyance direction of the medium.

  As illustrated in FIG. 1, the liquid ejecting apparatus 11 includes a transport device 12 that transports a continuous sheet P that is a long sheet, which is an example of a medium, and a continuous paper P that is transported on a support member 13 by the transport device 12. On the other hand, an ejection unit 14 that performs printing by ejecting ink and a heating unit 15 that heats the liquid ejection region RIL, which is a region in which the ejection unit 14 can eject ink onto the continuous paper P, are provided. Further, the liquid ejecting apparatus 11 includes a blower unit 16 for equalizing the temperature of the continuous paper P located in the liquid ejecting region RIL. In the liquid ejecting region RIL, the ejecting unit 14 can eject ink onto the continuous paper P in a range in which the ejecting unit 14 moves in the scanning direction X (the direction orthogonal to the paper surface in FIG. 1) which is the width direction of the continuous paper P. This is an important area.

  The transport device 12 includes a feeding unit 17 that feeds the continuous paper P, and a winding unit 18 that winds the continuous paper P fed from the feeding unit 17 and printed by the ejecting unit 14. In FIG. 1, the feeding unit 17 is disposed at a position on the right side that is upstream of the ejecting unit 14 in the transport direction Y (left direction in FIG. 1) of the continuous paper P, and is downstream of the ejecting unit 14. The winding unit 18 is disposed at the left position.

  The feeding portion 17 is provided with a feeding shaft 17a extending in the scanning direction X so as to be rotationally driven. The feeding shaft 17a supports the continuous paper P so as to be integrally rotatable with the feeding shaft 17a in a state where the continuous paper P is wound in a roll shape in advance. When the feeding shaft 17a is rotationally driven, the continuous paper P is fed from the feeding shaft 17a toward the downstream side of the transport path. On the downstream side of the feed shaft 17a in the transport path, a paper feed roller pair 19 is provided that guides the continuous paper P transported from the feed shaft 17a to the support member 13 by being driven to rotate while sandwiching the continuous paper P. .

  Disposed on the downstream side of the ejection section 14 in the transport path is a pair of paper discharge rollers 20 that guides a printed area on the continuous paper P from the support member 13 to the downstream side by rotating while sandwiching the continuous paper P. It has been.

  The winding unit 18 disposed on the downstream side of the paper discharge roller pair 20 in the transport path is provided with a winding shaft 18a extending in the scanning direction X so as to be rotationally driven. When the take-up shaft 18a is rotated, the printed continuous paper P conveyed from the paper discharge roller pair 20 is sequentially taken up by the take-up shaft 18a.

  The ejection unit 14 includes a box-shaped carriage 21 supported by a pair of support shafts 22 extending in the scanning direction X so as to be movable in the scanning direction X with respect to the continuous paper P. A liquid jet head 23 having a plurality of nozzles 23 a formed on a surface facing the continuous paper P is mounted on the carriage 21. A nozzle plate thermistor 24, which is an example of a second temperature detection unit that detects the temperature of the surface facing the continuous paper P, that is, the temperature of the plurality of nozzles 23 a, is attached to the liquid ejecting head 23. The nozzle plate thermistor 24 is composed of a thermoelectric element. Further, an L-shaped cover 25 made of, for example, aluminum or aluminum alloy is attached to the carriage 21 on the side opposite to the continuous paper P (upper side). The ejecting unit 14 configured as described above ejects ink from the plurality of nozzles 23 a toward the continuous paper P while moving in the scanning direction X with respect to the continuous paper P.

  A linear encoder 26 that detects the position of the ejection unit 14 in the scanning direction X is provided at a position between the pair of support shafts 22 on the upstream side of the transport path from the carriage 21. The linear encoder 26 includes a light emitting element and a light receiving element that are attached to the carriage 21, and a slit that faces the light emitting element and the light receiving element in the transport direction Y with a space therebetween.

  The heating unit 15 is disposed above a part of the cover 25 and at a position overlapping the cover 25 in the transport direction Y. That is, the heating unit 15 is disposed to face the cover 25. In other words, a portion of the injection unit 14 that faces the heating unit 15 is covered with the cover 25. The heating unit 15 includes a heater 27 that heats the continuous paper P positioned in the liquid ejecting region RIL by emitting infrared rays. On the upper side of the heater 27, a reflection plate 28 that reflects the infrared rays emitted from the heater 27 toward the continuous paper P is disposed.

  In addition, the heating unit 15 is an example of a first temperature detection unit that detects the temperature of the continuous paper P positioned in the liquid ejection region RIL on the downstream side of the transport path and on the home position side in the scanning direction X (see FIG. 2). An IR (infrared) sensor 29 is provided. The IR sensor 29 is a continuous paper positioned in the liquid ejecting region RIL by detecting the amount of infrared rays in the temperature detection region RDT (see FIG. 2) in the liquid ejecting region RIL in a non-contact manner with a built-in infrared sensor (not shown). It is a radiation thermometer that detects the temperature of P. The IR sensor 29 is disposed above the continuous paper P located in the liquid ejection region RIL so as to face the liquid ejection region RIL. The temperature detection region RDT is determined by the specifications of the IR sensor 29. The home position is a non-printing area on the right side of the continuous paper P as shown in FIG. A maintenance mechanism (not shown) that performs maintenance such as cleaning on the liquid ejecting head 23 is provided at the home position.

  As illustrated in FIG. 1, the liquid ejecting apparatus 11 includes a control device 30 that is an example of a control unit that controls operations of the transport device 12, the ejecting unit 14, the heating unit 15, and the air blowing unit 16. As shown in FIG. 3, the control device 30 includes the first detection temperature Tir, which is the temperature of the continuous paper P positioned in the liquid ejection region RIL detected by the IR sensor 29 and is the detection temperature of the temperature detection unit, and the nozzle. A second detection temperature Tth, which is the temperature of the plurality of nozzles 23a (see FIG. 1) detected by the plate thermistor 24, is input. Further, a position signal indicating the position of the ejection unit 14 in the scanning direction X detected by the linear encoder 26 and a print job are input to the control device 30. The print job includes the size of the continuous paper P, data such as an image to be printed on the continuous paper P, and a print command for executing printing.

  The control device 30 includes a heating control unit 31 that performs PWM control on the output of the heater 27, and a carriage drive unit 32 that controls movement of the carriage 21 (see FIG. 1) in the scanning direction X based on a print job. Further, the control device 30 controls the ejection control unit 33 that controls the ejection of ink to the liquid ejection region RIL by the liquid ejection head 23 based on the print job, and controls the transport of the continuous paper P by the transport device 12 based on the print job. The conveyance control part 34 and the ventilation control part 35 which controls the ventilation part 16 based on the temperature of the continuous paper P located in the liquid injection area | region RIL are provided.

  A memory 36, a temperature correction unit 37, a target temperature calculation unit 38, and a second determination unit 40 are connected to the heating control unit 31. The memory 36 stores a first detection temperature Tir of the IR sensor 29, a second detection temperature Tth of the nozzle plate thermistor 24, and arithmetic expressions and threshold values used in the temperature correction unit 37 and the target temperature calculation unit 38. A first determination unit 39 is connected to the temperature correction unit 37. The temperature correction unit 37 corrects the detection temperature of the IR sensor 29 in consideration of the effect of the infrared rays of the heater 27 reflected from the continuous paper P from the first detection temperature Tir of the IR sensor 29 being input to the IR sensor 29. To do. The first determination unit 39 determines whether or not the injection unit 14 has entered a range that affects the detection of the temperature of the IR sensor 29. The target temperature calculation unit 38 calculates the target temperature of the continuous paper P located in the liquid ejecting region RIL based on the second detected temperature Tth of the nozzle plate thermistor 24. The second determination unit 40 determines whether printing on the continuous paper P has been completed. Based on the signals input from the memory 36, the temperature correction unit 37, the target temperature calculation unit 38, and the second determination unit 40, the heating control unit 31 determines that the temperature of the continuous paper P positioned in the liquid ejection region RIL is liquid ejected. Feedback control is executed so as to coincide with the target temperature of the continuous paper P located in the region RIL. In this embodiment, PID (Proportional-Integral-Derivative) control is executed as feedback control.

  The air blowing control unit 35 drives the air blowing unit 16 when the temperature of the continuous paper P positioned in the liquid ejecting region RIL reaches around the target temperature of the continuous paper P positioned in the liquid ejecting region RIL. As a result, the temperature of the continuous paper P located in the liquid ejection region RIL is made uniform.

  Based on the above-described configuration, the control device 30 uses the heater 27 based on the temperature of the continuous paper P (first detection temperature Tir) positioned in the liquid ejection region RIL and the temperature of the plurality of nozzles 23a (second detection temperature Tth). Execute output control to control the output of. The output control processing procedure will be described below with reference to the flowchart of FIG.

  First, the control device 30 acquires the first detection temperature Tir, the second detection temperature Tth, the ON DUTY value (hereinafter simply referred to as the DUTY value) that is the output of the heater 27, and the type of medium (step S1). Note that the type of medium is acquired by inputting the type of medium used for printing by the user to the liquid ejecting apparatus 11 from the host computer or the operation unit of the liquid ejecting apparatus 11 (both not shown).

  Next, the control device 30 determines whether or not the injection unit 14 has entered a range that affects the detection of the temperature of the IR sensor 29 by the first determination unit 39 (step S2). The detailed contents of this determination will be described with reference to FIGS.

  Since the cover 25 of the injection unit 14 is made of metal such as aluminum, the infrared rays of the heater 27 are reflected. For this reason, the IR sensor 29 provided in the vicinity of the heater 27, when the ejection unit 14 enters the temperature detection region RDT, which is a region where the IR sensor 29 detects the temperature of the continuous paper P located in the liquid ejection region RIL, The temperature is detected based on the infrared rays of the heater 27 reflected by the cover 25. That is, the first detection temperature Tir of the IR sensor 29 is approximately equal to the temperature of the heater 27. Therefore, the IR sensor 29 erroneously detects the temperature of the continuous paper P positioned in the liquid ejection region RIL as the temperature of the heater 27.

  Further, when the injection unit 14 is positioned in the vicinity of the temperature detection region RDT without entering the temperature detection region RDT of the IR sensor 29, the infrared rays of the heater 27 reflected by the cover 25 affect the detection of the temperature of the IR sensor 29. There is a risk of giving.

  Therefore, the controller 30 includes a trigger determination that includes the temperature detection region RDT in the scanning direction X as a range in which the injection unit 14 affects the detection of the temperature of the IR sensor 29 and is larger than the temperature detection region RDT. A region RJT (see FIG. 2) is stored in the memory 36. As shown in FIG. 2, the trigger determination region RJT is a region that extends from the center position in the scanning direction X of the temperature detection region RDT to the both sides in the scanning direction X by the dimension in the scanning direction X. For this reason, the temperature detection region RDT is located in the center of the trigger determination region RJT in the scanning direction X.

  The first determination unit 39 outputs a trigger signal ST to the temperature correction unit 37 when at least a part of the injection unit 14 enters the trigger determination region RJT. The first determination unit 39 continues to output the trigger signal ST to the temperature correction unit 37 over a period in which at least a part of the injection unit 14 is located in the trigger determination region RJT. Note that whether or not at least part of the injection unit 14 has entered the trigger determination region RJT is determined based on the position signal of the linear encoder 26.

  For example, in FIG. 5, the injection unit 14 in the case where the IR sensor 29 detects the first detection temperature Tir every predetermined detection cycle and the output control is executed every cycle longer than the detection cycle of the first detection temperature Tir. And the operation of the IR sensor 29, the interruption of the output control, and the transition of the trigger signal ST. FIG. 5 shows a state where the temperature of the continuous paper P located in the liquid ejecting region RIL is rising. For this reason, as shown in FIG.5 (e), 1st detection temperature Tir is rising with progress of time. In addition, the operation | movement of the injection part 14 of Fig.5 (a) has shown the period when the injection part 14 has approached the temperature detection area | region RDT as "approaching."

  As shown in FIG. 5, at time t2 when the output control is executed, at least a part of the injection unit 14 has not entered the trigger determination region RJT (the trigger signal ST in FIG. 5 (d) is OFF), so the control device 30 acquires the 1st detection temperature Tir (51 degreeC) which IR sensor 29 detected at the time t1. That is, when executing the output control, the control device 30 acquires the first detected temperature Tir detected by the IR sensor 29 at the previous detection timing.

  On the other hand, when the injection unit 14 enters the trigger determination region RJT at time t3, the first determination unit 39 outputs the trigger signal ST as shown in FIG. At time t4, which is the detection timing of the IR sensor 29 in a state where the injection unit 14 has entered the temperature detection region RDT, the infrared rays of the heater 27 reflected by the cover 25 enter the IR sensor 29, so that the IR sensor 29 is The temperature (100 ° C.) of the heater 27 is detected as the first detection temperature Tir.

  Therefore, when the trigger signal ST is input to the temperature correction unit 37 (step S2: YES), the controller 30 causes the injection unit 14 to replace the first detected temperature Tir acquired in step S1 with the trigger determination region. The first detected temperature Tir immediately before entering the RJT is acquired (step S3). That is, in the output control executed at time t5 in FIG. 5, the first detected temperature Tir detected by the IR sensor 29 at time t4 is not acquired, and the IR sensor 29 immediately before the injection unit 14 enters the trigger determination region RJT. The first detection temperature Tir (52 ° C.) detected at time t2 that is the detection timing of is acquired.

  On the other hand, when the trigger signal ST is not input to the temperature correction unit 37 (step S2: NO), the control device 30 detects the first detected temperature Tir detected by the IR sensor 29 at the previous detection timing, that is, in step S1. The acquired first detection temperature Tir is maintained, and the process proceeds to step S4.

  Next, the control device 30 determines the first detection temperature based on the first detection temperature Tir acquired in step S1 or step S3 by the temperature correction unit 37, the DUTY value of the heater 27 acquired in step S1, and the type of medium. Tir is corrected (step S4).

Detailed contents of the correction of the first detection temperature Tir will be described with reference to FIGS.
In the design stage of the liquid ejecting apparatus 11, in correcting the first detection temperature Tir, the mounting angle of the IR sensor 29, that is, the angle of the IR sensor 29 with respect to the continuous paper P, the type of medium, and the capacity (wattage) of the heater 27 Based on the above, the relationship between the detection error of the IR sensor 29 and the heat amount DUTY value Hc of the heater 27 is acquired by a test or the like. The mounting angle of the IR sensor 29 and the capability of the heater 27 are uniquely determined at the design stage of the liquid ejecting apparatus 11. Therefore, the relationship between the detection error of the IR sensor 29 for each type of medium and the heat amount DUTY value Hc of the heater 27 is stored in the memory 36 in advance. The amount of heat DUTY value Hc of the heater 27 is obtained by multiplying the wattage of the heater 27 by the DUTY value.

  FIG. 6 shows a state where the attachment angle of the IR sensor 29 to the continuous paper P is 90 °, that is, the state where the IR sensor 29 faces the continuous paper P (see FIGS. 1 and 2), and the heater 27 is in a predetermined state. It shows the relationship between the detection error of the IR sensor 29 and the heat quantity DUTY value Hc of the heater 27 when the wattage and plain paper is used as the medium. Since the first detection temperature Tir of the IR sensor 29 is detected higher than the actual temperature of the continuous paper P positioned in the liquid ejection region RIL, the detection error of the IR sensor 29 is a continuous error positioned in the liquid ejection region RIL. It is obtained by subtracting the first detected temperature Tir of the IR sensor 29 from the actual temperature separately detected for the paper P.

  Then, an approximate curve of the relationship between the detection error of the IR sensor 29 and the heat quantity DUTY value Hc of the heater 27 can be created from a plurality of plotted values in FIG. As shown in the approximate curve in FIG. 6, the absolute value of the detection error of the IR sensor 29 increases as the heat amount DUTY value Hc of the heater 27 increases. A quadratic approximate expression representing the approximate curve of FIG. 6 is calculated by the following expression (1) using the absolute value of the detection error of the IR sensor 29 as the correction value Tc. The correction value Tc increases as the heat amount DUTY value Hc of the heater 27 increases.

Tc = z1 × Hc ² + z2 × Hc + z3 (1)
“Z1”, “z2”, and “z3” indicate coefficients determined by the infrared reflectance of the continuous paper P. The coefficients z1 to z3 are set for each type of medium and stored in the memory 36. For example, the values of the coefficients z1 to z3 for glossy paper are larger than the values of the coefficients z1 to z3 for plain paper.

  The temperature correction unit 37 calculates the correction value Tc by substituting the heat amount DUTY value Hc of the heater 27 into the above equation (1). The temperature correction unit 37 subtracts the temperature corresponding to the absolute value of the detection error of the IR sensor 29 from the first detection temperature Tir of the IR sensor 29 to obtain the actual temperature of the continuous paper P positioned in the liquid ejecting region RIL. . That is, the temperature correction unit 37 calculates a corrected temperature Tm obtained by correcting the first detected temperature Tir of the IR sensor 29 based on the following equation (2). Then, the temperature correction unit 37 outputs the correction temperature Tm to the memory 36, the target temperature calculation unit 38, and the heating control unit 31.

Tm = Tir−Tc (2)
Next, the control device 30 calculates the target temperature of the continuous paper P positioned in the liquid ejecting region RIL by the target temperature calculation unit 38 based on the second detection temperature Tth that is the detection temperature of the plurality of nozzles 23a (step S5). ).

Here, the detailed calculation content of the target temperature of the continuous paper P located in the liquid ejection region RIL will be described.
The target temperature of the continuous paper P located in the liquid ejection region RIL includes a reference target temperature Tgk stored in advance in the memory 36. The reference target temperature Tgk is a temperature suitable for drying ink ejected onto the continuous paper P located in the liquid ejecting region RIL. On the other hand, since the plurality of nozzles 23a are adjacent to the continuous paper P positioned in the liquid ejection region RIL, they are easily affected by the temperature of the continuous paper P positioned in the liquid ejection region RIL. Therefore, the target temperature calculation unit 38 controls the liquid ejection region RIL so as to suppress the temperature rise of the plurality of nozzles 23a based on the temperature of the continuous paper P positioned in the liquid ejection region RIL and the temperature of the plurality of nozzles 23a. The target temperature of the continuous paper P located at is calculated. The specific procedure is as follows.

  First, the target temperature calculation unit 38 calculates a difference (Tth−Tk) between the second detection temperature Tth and the temperature threshold value Tk, and integrates it for each detection period of the nozzle plate thermistor 24. Thereby, the target temperature calculation part 38 calculates | requires the integral value Di of the difference of 2nd detected temperature Tth and temperature threshold value Tk. The temperature threshold value Tk is a temperature at which there is a risk that the performance of the plurality of nozzles 23a may be deteriorated, such as ink clogging of the plurality of nozzles 23a, and is preset by a test or the like and stored in the memory 36. This temperature threshold Tk is lower than the reference target temperature Tgk. The integrated value Di is reset when the output of the heater 27 becomes “0”. The detection cycle of the nozzle plate thermistor 24 is the same length as the detection cycle of the IR sensor 29, for example.

  Then, the target temperature calculation unit 38 obtains a correction value Td from the following equation (3) based on the integral value Di. Note that “G” in Expression (3) is a constant that determines the degree to which the reference target temperature Tgk is lowered, and is preset by a test or the like and stored in the memory 36.

Td = Di × G (3)
Finally, the target temperature calculation unit 38 calculates the corrected target temperature Tgc by subtracting the correction value Td from the reference target temperature Tgk as shown in the following equation (4).

Tgc = Tgk−Td (4)
As shown in the equation (3), the correction value Td is proportional to the integral value Di, so the second detected temperature Tth is higher than the temperature threshold value Tk, that is, the integral value Di is a positive value, and the integral value Di is As the value increases, the correction value Td increases. For this reason, the correction target temperature Tgc decreases as the correction value Td increases from the equation (4), and thus the correction target temperature Tgc decreases as the integral value Di increases.

  By the way, when the second detection temperature Tth is lower than the temperature threshold value Tk, the difference between the second detection temperature Tth and the temperature threshold value Tk may be a negative value, and the integral value Di may be a negative value. Accordingly, when it is assumed that the corrected target temperature Tgc is calculated based on the above equations (3) and (4), the corrected target temperature Tgc becomes higher than the reference target temperature Tgk. When the second detection temperature Tth is lower than the temperature threshold Tk, the performance of the plurality of nozzles 23a does not deteriorate even if the reference target temperature Tgk is not changed.

  Therefore, the target temperature calculation unit 38 sets the integral value Di to “0” when the integral value Di becomes a negative value. As a result, the correction value Td is “0” in the above equation (3), so the correction target temperature Tgc matches the reference target temperature Tgk.

  Further, as the integrated value Di increases, the degree to which the corrected target temperature Tgc becomes lower than the reference target temperature Tgk increases. That is, if priority is given to suppressing the deterioration of the performance of the plurality of nozzles 23a, the ink ejected onto the continuous paper P located in the liquid ejecting region RIL may be difficult to dry.

  Therefore, the target temperature calculation unit 38 sets the integral upper limit value Dlim, which is the upper limit value, as the integral value Di, and integrates the integral value Di of the above equation (3) when the integral value Di is equal to or greater than the integral upper limit value Dlim. The correction value Td is calculated by substituting the upper limit value Dlim. The integral upper limit value Dlim is stored in the memory 36. Thereby, it is suppressed that correction | amendment target temperature Tgc becomes too low with respect to the reference target temperature Tgk.

  Further, when the temperature of the continuous paper P positioned in the liquid ejecting region RIL is sufficiently lower than the reference target temperature Tgk, the heat of the continuous paper P positioned in the liquid ejecting region RIL determines the temperature of the plurality of nozzles 23a. It is unlikely that the temperature will rise to a lower temperature. On the other hand, when the temperature of the continuous paper P positioned in the liquid ejecting region RIL is a temperature that matches or is close to the reference target temperature Tgk, the heat of the continuous paper P positioned in the liquid ejecting region RIL sets the temperature of the plurality of nozzles 23a. There is a high possibility of raising the temperature to a temperature at which the performance of 23a is lowered.

  Therefore, when the correction temperature Tm is equal to or lower than the correction target temperature Tgc, the target temperature calculation unit 38 calculates the target temperature of the continuous paper P positioned in the liquid ejection region RIL as the reference target temperature Tgk, and the correction temperature Tm is the correction target temperature. When the temperature is higher than Tgc, the target temperature of the continuous paper P located in the liquid ejecting region RIL is calculated as the corrected target temperature Tgc.

  As described above, when the temperature of the plurality of nozzles 23a and the temperature of the continuous paper P positioned in the liquid ejection region RIL are low, the target temperature calculation unit 38 uses the target temperature of the continuous paper P positioned in the liquid ejection region RIL as the reference target. Calculated as temperature Tgk. On the other hand, when the temperature of the plurality of nozzles 23a is sufficiently high and the temperature of the continuous paper P located in the liquid ejection region RIL is close to the reference target temperature Tgk, the target temperature calculation unit 38 is continuously located in the liquid ejection region RIL. The target temperature of the paper P is calculated as a corrected target temperature Tgc lower than the reference target temperature Tgk.

  Next, the control device 30 calculates a target DUTY value that is an on-DUTY value that is a target of the heater 27 based on the correction temperature Tm and the target temperature of the continuous paper P positioned in the liquid ejection region RIL by the heating control unit 31. (Step S6). The target DUTY value increases as the difference between the correction temperature Tm and the target temperature of the continuous paper P positioned in the liquid ejection region RIL increases. Then, the control device 30 controls the heater 27 so that the DUTY value matches the target DUTY value (step S7).

  Next, the control device 30 determines whether printing on the continuous paper P is completed based on the print job by the second determination unit 40 (step S8). When it is determined that the printing on the continuous paper P has been completed (step S8: YES), the control device 30 ends the output control. In the control device 30, when printing on the continuous paper P is completed, the ejection control unit 33, the carriage drive unit 32, and the conveyance control unit 34 execute processing for completing the printing of the continuous paper P. On the other hand, when the control device 30 determines that printing on the continuous paper P is not completed (step S8: NO), the control device 30 proceeds to step S1.

One execution mode of output control will be described with reference to the time chart of FIG. In addition, the dashed-dotted line of FIG.7 (b) shows transition of the target temperature of the continuous paper P located in the liquid ejection area | region RIL.
First, at time t11 shown in FIG. 7, heating of the continuous paper P positioned in the liquid ejection region RIL by the heater 27 is started. At this time, as shown in FIG. 7A, the DUTY value of the heater 27 is “100%”. That is, the heater 27 heats the continuous paper P positioned in the liquid ejection region RIL with the maximum output. As a result, as shown in FIG. 7B, the temperature of the continuous paper P positioned in the liquid ejecting region RIL increases with time. When the correction temperature Tm, which is the temperature of the continuous paper P positioned in the liquid ejecting region RIL, approaches the target target temperature Tgk, which is the target temperature of the continuous paper P positioned in the liquid ejecting region RIL, to some extent (time t12), the heater 27 DUTY value decreases from “100%”. For this reason, after time t12, the degree of the temperature increase of the correction temperature Tm becomes small.

  Next, at time t13 shown in FIG. 7C, printing on the continuous paper P is started. Accordingly, since the ejecting unit 14 is positioned in the region where the heater 27 is heated from the home position, a plurality of ejecting units 14 are heated by the heat of the continuous paper P located in the liquid ejecting region RIL and the heat of the heater 27. The second detection temperature Tth, which is the temperature of the nozzle 23a, increases. Then, as shown in FIGS. 7B and 7C, when the second detected temperature Tth becomes higher than the temperature threshold Tk at the time t14 and the correction temperature Tm becomes close to the reference target temperature Tgk, the liquid ejection region RIL is entered. The target temperature of the continuous paper P positioned is changed from the reference target temperature Tgk to the corrected target temperature Tgc. Since the second detected temperature Tth is higher than the temperature threshold value Tk during the period from time t14 to time t16, the corrected target temperature Tgc decreases with the passage of time during the period from time t14 to time t16. For this reason, in the period from time t14 to time t16, the correction temperature Tm decreases with time. As a result, the influence of the heat of the continuous paper P located in the liquid ejecting region RIL on the plurality of nozzles 23a is reduced, and therefore, as shown in FIG. 7C, the second detected temperature Tth with the passage of time from time t14. And the second detected temperature Tth starts to decrease at time t15.

  On the other hand, since the second detected temperature Tth is lower than the temperature threshold Tk in the period from time t16 to time t17, the corrected target temperature Tgc increases with time in the period from time t16 to time t17. As a result, the influence of the heat of the continuous paper P in the liquid ejection region RIL on the plurality of nozzles 23a is increased, so that the second detection temperature Tth increases with the passage of time from time t16 as shown in FIG. 7C. To do.

  As described above, according to the output control, while the temperature of the continuous paper P positioned in the liquid ejecting region RIL is maintained at a temperature necessary for drying the ink ejected onto the continuous paper P by the ejecting unit 14, a plurality of the papers are maintained. The deterioration of the performance of the nozzle 23a is suppressed.

According to the liquid ejecting apparatus 11 of the present embodiment, the following effects can be obtained.
(1) The liquid ejecting apparatus 11 corrects the first detection temperature Tir of the IR sensor 29 based on the heat amount DUTY value Hc of the heater 27, and based on the correction temperature Tm that is the corrected first detection temperature Tir. Set the DUTY value. Therefore, the correction temperature Tm is a temperature that takes into account the detection error of the IR sensor 29 that occurs when the infrared rays of the heater 27 are reflected by the continuous paper P and enter the IR sensor 29. For this reason, the correction temperature Tm is closer to the actual temperature of the continuous paper P located in the liquid ejection region RIL. Therefore, the heater 27 can be controlled based on a temperature closer to the actual temperature of the continuous paper P located in the liquid ejection region RIL.

  (2) The liquid ejecting apparatus 11 obtains the correction value Tc corresponding to the heat amount DUTY value Hc of the heater 27 and subtracts the correction value Tc from the first detection temperature Tir to obtain the correction temperature Tm. For this reason, compared with the case where the correction value Tc is assumed to be a constant, the correction temperature Tm can be made closer to the actual temperature of the continuous paper P positioned in the liquid ejection region RIL for the entire output range of the heater 27. .

  (3) As shown in FIG. 6, for example, the detection error of the IR sensor 29 may increase as the heat quantity DUTY value Hc of the heater 27 increases. Even in such a case, since the correction value Tc is set to increase as the heat amount DUTY value Hc of the heater 27 increases, the correction temperature Tm is set to the actual temperature of the continuous paper P positioned in the liquid ejection region RIL. Can be closer.

  (4) Since the reflectance of the infrared rays irradiated from the heater 27 differs depending on the type of medium, the first detection temperature Tir may differ depending on the type of medium even if the heater 27 has the same heat quantity DUTY value Hc. In this regard, according to the present embodiment, since the values of the coefficients z1 to z3 in the above formula (1) are changed according to the type of the medium, the correction value Tc differs depending on the type of the medium. Therefore, an appropriate correction value Tc can be obtained for the type of medium, and the correction temperature Tm can be brought close to the actual temperature of the medium located in the liquid ejection region RIL.

  (5) The IR sensor 29 is disposed so as to face the continuous paper P. For this reason, as compared with the configuration in which the IR sensor 29 is assumed to be inclined with respect to the continuous paper P, the variation in temperature detected in the temperature detection region RDT of the IR sensor 29 is reduced.

  On the other hand, compared with a configuration in which the IR sensor 29 is assumed to be inclined with respect to the continuous paper P, the infrared rays of the heater 27 reflected by the continuous paper P are likely to enter the IR sensor 29. However, since the first detection temperature Tir of the IR sensor 29 is corrected based on the heat amount DUTY value Hc of the heater 27, the correction temperature Tm can be brought close to the actual temperature of the continuous paper P positioned in the liquid ejection region RIL. .

  (6) According to the liquid ejecting apparatus 11, the first detected temperature Tir detected by the IR sensor 29 when the ejecting unit 14 is positioned in the temperature detection region RDT in the output control is not used for controlling the heater 27. For this reason, since the heater 27 is not controlled based on the erroneous first detection temperature Tir of the IR sensor 29, it is possible to suppress a decrease in the accuracy of the control of the heater 27.

  (7) The infrared rays of the heater 27 reflected by the injection unit 14 may enter the IR sensor 29 even when the injection unit 14 is located in the vicinity of the temperature detection region RDT. In this regard, according to the output control of this embodiment, the first detection temperature Tir detected by the IR sensor 29 when the injection unit 14 enters the trigger determination region RJT including the temperature detection region RDT is used for the control of the heater 27. Since it is not used, it is possible to further suppress a decrease in accuracy of control of the heater 27.

  (8) The temperature detection region RDT is located in the center of the trigger determination region RJT in the scanning direction X. For this reason, the range in which the first detection temperature Tir that may affect the detection of the temperature of the IR sensor 29 by the injection unit 14 is not used for the reciprocation of the injection unit 14 in the scanning direction X is the same. For this reason, the fall of the control precision of the heater 27 can be similarly suppressed with respect to the forward operation and the backward operation of the injection unit 14.

  (9) The liquid ejecting apparatus 11 uses the first detection temperature Tir detected by the IR sensor 29 immediately before the ejecting unit 14 enters the trigger determination region RJT when the ejecting unit 14 enters the trigger determination region RJT in the output control. Based on this, the heater 27 is controlled. For this reason, the temperature change by the heater 27 of the continuous paper P located in the liquid ejection region RIL is reflected, not the first detection temperature Tir which may affect the temperature detection of the IR sensor 29 by the ejection unit 14. The heater 27 is controlled using the first detection temperature Tir. Accordingly, it is possible to suppress a decrease in accuracy of control of the heater 27.

  (10) The injection unit 14 includes a cover 25 that covers a portion facing the heating unit 15. For this reason, when the infrared rays of the heater 27 are prevented from entering the liquid ejecting head 23, the liquid ejecting head 23 is prevented from being excessively heated. However, since the cover 25 reflects the infrared rays of the heater 27, the IR sensor 29 may detect the temperature of the heater 27 when the ejection unit 14 is positioned within the temperature detection region RDT of the IR sensor 29. In this regard, the liquid ejecting apparatus 11 suppresses malfunction of the heater 27 because the first detected temperature Tir detected by the IR sensor 29 when the ejecting unit 14 enters the temperature detection region RDT in the output control is not used. Is done. Therefore, it is possible to suppress both the liquid jet head 23 from becoming excessively high temperature and the malfunction of the heater 27.

  (11) The liquid ejecting apparatus 11 sets the DUTY value of the heater 27 in the liquid ejecting region RIL for setting the DUTY value of the heater 27 based on the first detected temperature Tir of the IR sensor 29 and the second detected temperature Tth of the nozzle plate thermistor 24 in the output control. The target temperature of the continuous paper P located is calculated. For this reason, in order to reduce the DUTY value of the heater 27 when the temperature of the plurality of nozzles 23a is increased by setting the DUTY value of the heater 27 in consideration of the temperature of the plurality of nozzles 23a of the injection unit 14, It can suppress that the temperature of the some nozzle 23a becomes high too much.

  (12) In the liquid ejection device 11, in the output control, the liquid ejection region RIL increases as the second detection temperature Tth is greater than the temperature threshold Tk and the integrated value Di of the difference between the second detection temperature Tth and the temperature threshold Tk increases. The target temperature of the continuous paper P located at is lowered. For this reason, as the temperature of the plurality of nozzles 23a continues to be high, the DUTY value of the heater 27 decreases, so that the temperature of the plurality of nozzles 23a is less likely to increase and is likely to decrease.

  (13) When the temperature of the continuous paper P positioned in the liquid ejecting region RIL is low, the influence of the heat of the continuous paper P on the plurality of nozzles 23a of the ejecting unit 14 is reduced, while the continuous paper positioned in the liquid ejecting region RIL. It is necessary to quickly raise the temperature of P to the reference target temperature Tgk. On the other hand, when the temperature of the continuous paper P positioned in the liquid ejecting region RIL is high, the influence of the heat of the continuous paper P on the plurality of nozzles 23a is increased, while the temperature of the continuous paper P positioned in the liquid ejecting region RIL is the reference Since the temperature is close to the target temperature Tgk or higher than the reference target temperature Tgk, there is no need to quickly increase the temperature of the continuous paper P positioned in the liquid ejection region RIL.

  Based on such matters, when the first detected temperature Tir is equal to or lower than the corrected target temperature Tgc, the liquid ejecting apparatus 11 controls the heater 27 based on the reference target temperature Tgk, and the first detected temperature Tir is the corrected target temperature. When the temperature is higher than Tgc, the heater 27 is controlled based on the corrected target temperature Tgc. For this reason, it is possible to control the heater 27 so that the ink ejected onto the continuous paper P positioned in the liquid ejecting region RIL is easy to dry and the temperature rise of the plurality of nozzles 23a is suppressed.

  (14) The liquid ejecting apparatus 11 includes the blower unit 16 for equalizing the temperature of the continuous paper P positioned in the liquid ejecting region RIL. For this reason, since the dispersion | variation in the detection of the temperature of the liquid ejection area | region RIL in the continuous paper P by the IR sensor 29 is suppressed, the fall of the detection accuracy of the 1st detection temperature Tir of the IR sensor 29 is suppressed.

The present embodiment may be changed to another embodiment as described below.
The IR sensor 29 according to the above embodiment is not limited to being disposed facing the continuous paper P, and may be disposed in a state inclined with respect to the continuous paper P on the support member 13.

The IR sensor 29 according to the above embodiment may be disposed on the upstream side of the transport path from the ejection unit 14 or may be disposed on the support member 13 side with respect to the continuous paper P.
-In above-mentioned embodiment, it may replace with the nozzle plate thermistor 24 which consists of a thermoelectric element as a 2nd temperature detection part, and may use the sensor of other temperature detection systems, such as infrared rays.

  In the above embodiment, the trigger determination region RJT is a region extending from the center position in the scanning direction X of the temperature detection region RDT to both ends in the scanning direction X by the dimension in the scanning direction X. The range in the scanning direction X may be reduced as long as the infrared rays are reflected on the ejection unit 14 and the influence on the detection of the temperature of the IR sensor 29 is not excessively increased.

In the above embodiment, the temperature detection region RDT may be located closer to the home position or closer to the anti-home position in the trigger determination region RJT.
-In step S2 of output control of the said embodiment, you may change into determination whether the whole injection part 14 entered into the trigger determination area | region RJT.

  -In step S2 of the output control of the said embodiment, you may change into determination whether the injection part 14 entered temperature detection area | region RDT. In this case, the temperature correction unit 37 acquires the first detection temperature Tir detected by the IR sensor 29 immediately before the injection unit 14 enters the temperature detection region RDT. According to this configuration, the temperature change by the heater 27 in the liquid ejection region RIL in the continuous paper P is reflected most, not the first detection temperature Tir that the ejection unit 14 has influenced the temperature detection of the IR sensor 29. Since the heater 27 is controlled using the temperature as the first detection temperature Tir, it is possible to suppress a decrease in the accuracy of the control of the heater 27.

  In step S3 of the output control of the above embodiment, instead of the first detection temperature Tir immediately before the injection unit 14 enters the trigger determination region RJT, the IR sensor starts when the injection unit 14 enters the trigger determination region RJT. You may acquire 1st detection temperature Tir several cycles before in 29 detection periods.

  In step S3 of the output control of the above embodiment, an alternative temperature stored in the memory 36 may be used instead of the first detected temperature Tir immediately before the injection unit 14 enters the trigger determination region RJT. This alternative temperature may be a constant or an average value of the first detection temperatures Tir of several cycles in the detection cycle of the IR sensor 29.

  In step S4 of the output control of the above embodiment, the relationship between the heat amount DUTY value Hc of the heater 27 and the correction coefficient is defined in advance, and the correction temperature Tm is calculated by multiplying the first detection temperature Tir by the correction coefficient. May be. This correction coefficient decreases as the heat quantity DUTY value Hc of the heater 27 increases.

In step S4 of the output control of the above embodiment, the correction value Tc may be a constant. The correction value Tc may be a different constant for each type of medium.
In step S4 of the output control of the above embodiment, the expression (1) for obtaining the correction value Tc changes the values of the coefficients z1 to z3 according to the type of the medium. Each value of z3 may be set as a constant value.

  In step S4 of the output control of the above embodiment, instead of calculating the correction value Tc based on the quadratic approximate expression of the above expression (1), a calculation table of the heat amount DUTY value Hc of the heater 27 and the correction value Tc is stored in advance. A correction value Tc may be obtained based on the calculation table.

  In step S5 of the output control of the above embodiment, instead of calculating the correction target temperature Tgc by subtracting the correction value Td from the reference target temperature Tgk, the relationship between the heat amount DUTY value Hc of the heater 27 and the correction coefficient May be calculated in advance, and the corrected target temperature Tgc may be calculated by multiplying the reference target temperature Tgk by a correction coefficient. This correction coefficient decreases as the heat quantity DUTY value Hc of the heater 27 increases.

In step S5 of the output control of the above embodiment, the correction value Td may be a constant.
In step S5 of the output control of the above embodiment, the corrected target temperature Tgc may be a constant. In this case, the calculations according to the above formulas (3) and (4) are omitted.

  In the output control of the above embodiment, the interrupt cycle of the output control may be the same as the detection cycle of the IR sensor 29 or shorter than the detection cycle of the IR sensor 29. According to this configuration, the correction temperature Tm can quickly follow the target temperature of the continuous paper P positioned in the liquid ejection region RIL. For this reason, the control accuracy of the heater 27 is improved.

  In the above embodiment, the heating unit 15 may include a plurality of heaters 27. In this case, each heater 27 may be individually controlled. For example, the correction temperature Tm is calculated as follows. First, the temperature correction unit 37 calculates the amount of heat of each heater 27 by multiplying the DUTY value of each heater 27 by the wattage, and by multiplying the maximum value (100%) of the DUTY value of each heater 27 by the wattage. The total heat amount of each heater 27 is calculated. Then, the temperature correction unit 37 calculates the heat quantity DUTY value Hc of the plurality of heaters 27 by dividing the total heat quantity of each heater 27 from the total heat quantity of each heater 27. Similarly to the above embodiment, the temperature correction unit 37 calculates the correction value Tc by substituting the heat quantity DUTY values Hc of the plurality of heaters 27 into the above equation (1), and the correction value Tc into the above equation (2). Is used to calculate the correction temperature Tm.

-The cover 25 of the said embodiment is not restricted to metal, The resin made of the coating which reflected infrared rays was made | formed. Further, the cover 25 may be omitted.
In the above embodiment, the liquid ejecting apparatus 11 may be a dot impact printer or a laser printer as long as it can print on a medium. Further, the liquid ejecting apparatus 11 is not limited to a configuration having only a printing function, and may be a multifunction machine. Furthermore, the liquid ejecting apparatus 11 is not limited to a serial printer, and may be a line printer or a page printer.

  -The medium is not limited to continuous paper P, but may be cut paper, resin film, metal foil, metal film, resin-metal composite film (laminate film), woven fabric, non-woven fabric, ceramic sheet, etc. Good.

  The state of the liquid ejected as a minute amount of liquid droplets from the liquid ejecting head 23 includes those that are tailed in a granular shape, a tear shape, or a thread shape. The liquid here may be any material that can be ejected from the liquid ejecting head 23. For example, it may be in the state when the substance is in a liquid phase, and includes liquids with high or low viscosity, sols, gels, other inorganic solvents, organic solvents, solutions, and fluids such as liquid resins. Shall be. Further, not only a liquid as one state of a substance but also a particle in which solid particles such as a pigment are dissolved, dispersed or mixed in a solvent is included. When the liquid is an ink, the ink includes various liquid compositions such as general water-based ink and oil-based ink, gel ink, and hot-melt ink.

  DESCRIPTION OF SYMBOLS 11 ... Liquid injection apparatus, 14 ... Injection part, 15 ... Heating part, 16 ... Air blower, 23a ... Nozzle, 24 ... Nozzle plate thermistor which is an example of 2nd temperature detection part, 29 ... In an example of 1st temperature detection part A certain IR sensor, 30 ... a control device as an example of a control unit, RIL ... a liquid ejection region, Tir ... a first detection temperature, Tth ... a second detection temperature, Tgk ... a reference target temperature, Tgc ... a correction target temperature, Tk ... predetermined A temperature threshold that is a threshold of P, continuous paper that is an example of a medium.

Claims (5)

An ejection unit that ejects liquid onto the medium;
A heating unit that heats a liquid ejection region that is a region in which the ejection unit can eject the liquid to the medium;
A first temperature detector that detects the temperature of the liquid ejection region;
A second temperature detection unit that detects the temperature of the surface on which the nozzle is formed, facing the medium in the ejection unit;
A liquid ejecting apparatus comprising: a control unit that controls the heating unit based on a first detection temperature of the first temperature detection unit and a second detection temperature of the second temperature detection unit. When the second detected temperature is equal to or lower than a temperature threshold, the control unit controls the heating unit so that the temperature of the medium becomes a reference target temperature, while the second detected temperature exceeds the temperature threshold. The liquid ejecting apparatus according to claim 1, wherein the heating unit is controlled such that the first detected temperature is equal to or lower than the reference target temperature. The control unit is configured to control the heating unit as the second detection temperature is higher than the temperature threshold and an integral value of a difference between the second detection temperature and the temperature threshold increases. The liquid ejecting apparatus according to claim 2, wherein the target temperature is lowered. When the second detected temperature exceeds the temperature threshold, the control unit obtains a corrected target temperature that is corrected to be lower than the reference target temperature as a target temperature of the medium for controlling the heating unit. And when the first detected temperature is equal to or lower than the corrected target temperature, the heating unit is controlled based on the reference target temperature, and when the first detected temperature is higher than the corrected target temperature, the correction is performed. The liquid ejecting apparatus according to claim 2, wherein the heating unit is controlled based on a target temperature. The liquid ejecting apparatus according to claim 1, further comprising a blower unit that equalizes a temperature of the medium.