Inkjet printing equipment

Abstract

To provide an inkjet printing device that can reduce the degradation of print quality. [Solution] The inkjet head 46 prints by ejecting ink onto the printing medium 37 while moving in the main scanning direction. Drying units 41A to 41N are arranged along the main scanning direction and heat the printing medium 37 to dry it. Medium temperature sensors 29A to 29N are provided corresponding to each of the drying units 41A to 41N and detect the temperature of the printing medium 37 in the area heated by each drying unit 41A to 41N. The CPU controls the amount of heating of the drying units 41A to 41N using the temperature of the printing medium 37 detected by the medium temperature sensors 29A to 29N.

Description

Technical Field

[0001] The present invention relates to an inkjet printing apparatus.

Background Art

[0002] In an inkjet printing apparatus that performs printing by discharging ink onto a printing medium while moving an inkjet head, the printed medium onto which ink has been discharged is heated by a heater or the like and dried.

[0003] Also, in such an inkjet printing apparatus, there is known a technique for controlling the temperature of a plurality of heaters arranged along the moving direction of a carriage while detecting the temperature of a printing medium with a temperature sensor arranged on the carriage that holds the inkjet head (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, when performing temperature control of a plurality of heaters using a temperature sensor arranged on the carriage as in the above-described technique, the temperature control cycle of each heater depends on the operation of the carriage.

[0006] For example, at the center of the moving range of the carriage, since the temperature control of the heater is performed at a frequency of once per one-way movement time of the carriage, the temperature control cycle may be long.

[0007] Furthermore, for example, at the ends of the carriage's range of motion, heater temperature control is performed immediately after the carriage starts moving in one direction and just before it finishes moving in the opposite direction. As a result, at the ends of the carriage's range of motion, heater temperature control is performed only once every approximately twice the time it takes for the carriage to move in one direction.

[0008] Furthermore, as mentioned above, the heater temperature control period differs between the center and the ends of the carriage's range of motion. Additionally, the heater temperature control period differs at other positions within the carriage's range of motion compared to the center and ends. In other words, the heater temperature control period differs depending on the position in the carriage's direction of motion.

[0009] These factors may lead to insufficient or uneven drying of the printing medium, potentially resulting in a decrease in print quality.

[0010] Furthermore, generally, the carriage movement speed differs depending on the printing mode, with the carriage moving slower in printing modes that have higher print resolution. As a result, in printing modes with relatively high print resolution, the temperature control cycle of each heater becomes longer, which may cause a deviation from the target temperature of the printing medium. Consequently, this may result in a decrease in print quality due to insufficient drying of the printing medium, or a decrease in print quality due to poor ink ejection caused by excessive heating of the printing medium, which dries out the nozzles of the inkjet head.

[0011] The present invention has been made in view of the above, and aims to provide an inkjet printing apparatus that can reduce the deterioration of print quality. [Means for solving the problem]

[0012] To achieve the above objective, the inkjet printing apparatus of the present invention is characterized by comprising: an inkjet head that ejects ink onto a printing medium while moving in a predetermined direction to print; a plurality of drying units arranged along the predetermined direction and heating and drying the printing medium; a plurality of media temperature detection units provided corresponding to each of the plurality of drying units and detecting the temperature of the printing medium in the region heated by the respective drying unit; and a control unit that controls the amount of heating of the plurality of drying units using the temperature of the printing medium detected by the respective media temperature detection unit. [Effects of the Invention]

[0013] According to the inkjet printing apparatus of the present invention, the deterioration of print quality can be reduced. [Brief explanation of the drawing]

[0014] [Figure 1] This is a perspective view showing the schematic configuration of an inkjet printing apparatus according to an embodiment. [Figure 2] Figure 1 is a side view showing the schematic configuration of the inkjet printing apparatus. [Figure 3] Figure 1 is a control block diagram of the inkjet printing apparatus. [Figure 4] Figure 1 is a flowchart illustrating the basic operation of the inkjet printing device shown. [Figure 5] Figure 1 is a flowchart illustrating the printing operation of the inkjet printer shown. [Figure 6] This is a flowchart to explain the control of the heating amount in the drying section. [Figure 7] This is a flowchart to explain the control of the heating amount in the drying section. [Figure 8] This is a flowchart to explain the control of the heating amount in the drying section. [Figure 9] This figure shows the temperature changes of the printing medium as it is heated by the drying section. [Figure 10] This figure shows the control history of the heating amount in the drying section prior to the non-detection period. [Figure 11] This is a diagram for explaining the control of the heating amount of the drying unit during the non-detection period. [Figure 12] This is a diagram showing the control history of the heating amount of the drying unit before the non-detection period and the control content of the heating amount of the drying unit during the non-detection period. [Figure 13] This is a plan view showing a configuration using a linear encoder to detect the presence of a head unit between a medium temperature sensor and a printing medium. [Figure 14] This is a perspective view showing a configuration using a linear encoder to detect the presence of a head unit between a medium temperature sensor and a printing medium. <\ [Figure 15] This is a plan view showing a configuration using a reflective optical sensor to detect the presence of a head unit between a medium temperature sensor and a printing medium. [Figure 16] This is a perspective view showing a configuration using a reflective optical sensor to detect the presence of a head unit between a medium temperature sensor and a printing medium. [Figure 17] This is a plan view showing a configuration using a transmissive optical sensor to detect the presence of a head unit between a medium temperature sensor and a printing medium. [[ID=2i]] [Figure 18] This is a perspective view showing a configuration using a transmissive optical sensor to detect the presence of a head unit between a medium temperature sensor and a printing mediun.

Embodiments for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same or equivalent parts and components are denoted by the same or equivalent reference numerals throughout the drawings.

[0016] It should be noted that there was a small error in the original text where "<\ [Figure 15] " should probably be " [Figure 15] ", and in the translation of the last line of the 23rd item, "printing mediun" should be "printing medium". These have been corrected in the translation.The embodiments shown below illustrate devices and the like that embody the technical concept of this invention, and the technical concept of this invention does not specify the material, shape, structure, arrangement, etc., of each component as described below. The technical concept of this invention can be modified in various ways within the scope of the claims.

[0017] Figure 1 is a perspective view showing a schematic configuration of an inkjet printing apparatus according to an embodiment of the present invention. Figure 2 is a side view showing a schematic configuration of the inkjet printing apparatus shown in Figure 1. Figure 3 is a control block diagram of the inkjet printing apparatus shown in Figure 1. In the following description, the up, down, left, right, front, and back directions indicated by the arrows in Figure 1 refer to the up, down, left, right, front, and back directions in the inkjet printing apparatus.

[0018] As shown in Figures 1 to 3, the inkjet printing apparatus 1 according to this embodiment includes a printing medium roll support shaft 11, a winding shaft 12, a winding drive motor 13, a winding drive motor driver 14, printing medium guides 15, 16, a plurality of platens 17A, 17B, ..., 17N, a plurality of platen heaters 18A, 18B, ..., 18N, a plurality of platen heater drivers 19A, 19B, ..., 19N, a main scanning drive guide 20, a main scanning drive motor 21, a main scanning drive motor driver 22, and a head unit. The system comprises 23, a head drive unit 24, a head unit temperature sensor (corresponding to a head unit temperature detection unit) 25, multiple fan heater units 26A, 26B, ..., 26N, multiple blower fan drivers 27A, 27B, ..., 27N, multiple fan heater drivers 28A, 28B, ..., 28N, multiple media temperature sensors (corresponding to media temperature detection units) 29A, 29B, ..., 29N, an ambient temperature sensor 30, an operation panel 31, a timer 32, a CPU (corresponding to a control unit) 33, and a memory 34. Note that the alphabetical subscripts in the symbols such as platens 17A, 17B, ..., 17N may be omitted and the system may be represented collectively.

[0019] The printing medium roll support shaft 11 rotatably supports the printing medium roll 36. The printing medium roll 36 is a roll in which a printing medium 37, consisting of a strip of paper or the like, is wound. The printing medium roll support shaft 11 is located below the rear side of the platen 17.

[0020] The winding shaft 12 winds up the printing medium 37, pulling it out from the printing medium roll 36 and transporting it via the platen 17. The winding shaft 12 is positioned below the front of the platen 17.

[0021] The winding drive motor 13 rotates the winding shaft 12. The winding drive motor driver 14 drives the winding drive motor 13.

[0022] The printing medium guide 15 guides the printing medium 37 between the printing medium roll 36 and the platen 17. The printing medium guide 16 guides the printing medium 37 between the platen 17 and the winding shaft 12.

[0023] The platens 17A to 17N support the printing medium 37. The platens 17A to 17N are arranged along the left-right direction. The platen 17 has multiple suction holes for air intake. A suction fan (not shown) draws air through the suction holes of the platen 17, generating suction force at the suction holes and causing the printing medium 37 to adhere to the platen 17.

[0024] Platen heaters 18A to 18N are provided corresponding to platens 17A to 17N, respectively, and heat platens 17A to 17N. Platen heater 18 heats platen 17 in order to heat the printing medium 37, thereby drying the printing medium 37 from which the ink has been ejected. Platen heater 18 is located on the underside of platen 17.

[0025] Here, a drying section 41 is formed by corresponding platen heaters 18 and fan heater units 26 to heat and dry the printing medium 37. Specifically, a plurality of drying sections 41A to 41N are formed by platen heaters 18A to 18N and fan heater units 26A to 26N, arranged along the left-right direction.

[0026] Platen heater drivers 19A to 19N drive platen heaters 18A to 18N, respectively.

[0027] The main scan drive guide 20 guides the head unit 23 to move in the left-right direction (main scan direction). The main scan drive guide 20 is formed in an elongated shape that extends in the left-right direction.

[0028] The main scan drive motor 21 moves the head unit 23 in the left-right direction. The main scan drive motor driver 22 drives the main scan drive motor 21.

[0029] The head unit 23 performs printing by ejecting ink onto the printing medium 37 while moving in the left-right direction (corresponding to a predetermined direction). The head unit 23 is positioned between the platen 17 and the medium temperature sensor 29 in the vertical direction. Therefore, the head unit 23 moves back and forth in the left-right direction between the medium temperature sensors 29A to 29N in the vertical direction and the printing medium 37. The head unit 23 comprises a plurality of inkjet heads 46 and a carriage 47.

[0030] The inkjet head 46 has multiple nozzles formed on its lower nozzle surface, and ejects ink from these nozzles.

[0031] The carriage 47 holds the inkjet head 46. The carriage 47 is formed in a hollow, box-like shape.

[0032] The head drive unit 24 drives the inkjet head 46.

[0033] The head unit temperature sensor 25 detects the temperature of the head unit 23. The head unit temperature sensor 25 is installed on the carriage 47.

[0034] The fan heater units 26A to 26N are each positioned above the platens 17A to 17N and heat and dry the printing medium 37 by blowing warm air into the area through which the head unit 23 of the printing medium 37 passes. Each fan heater unit 26A to 26N is equipped with a blower fan 51A to 51N, a fan heater 52A to 52N, and a duct 53A to 53N.

[0035] As shown in Figure 2, the blower fan 51 draws in air from below and blows it towards the fan heater 52.

[0036] The fan heater 52 heats the air from the blower fan 51 to produce warm air.

[0037] The duct 53 blows warm air from the fan heater 52 downwards toward the printing medium 37.

[0038] The blower fan drivers 27A to 27N drive the blower fans 51A to 51N, respectively.

[0039] Fan heater drivers 28A to 28N drive fan heaters 52A to 52N, respectively.

[0040] The media temperature sensors 29A to 29N are arranged along the left-right direction, corresponding to the drying sections 41A to 41N, and each detects the temperature of the printing medium 37 in the area heated by the drying sections 41A to 41N. If a head unit 23 is present between each of the media temperature sensors 29A to 29N and the printing medium 37, the temperature of the head unit 23 is also detected. The media temperature sensor 29 is located at the front end of the duct 53. The media temperature sensor 29 consists of a non-contact type temperature sensor.

[0041] The ambient temperature sensor 30 detects the ambient temperature of the location where the inkjet printing device 1 is installed.

[0042] The control panel 31 displays various input screens and accepts user input operations. The control panel 31 comprises a display unit consisting of a liquid crystal display panel or the like, and an input unit (not shown) having various operation buttons, a touch panel, or the like.

[0043] The timer 32 sends an adjustment timing signal to the CPU 33 that indicates the adjustment timing at predetermined intervals for adjusting the amount of heat applied to the printing medium 37 by the drying unit 41.

[0044] The CPU 33 controls the operation of each part of the inkjet printer 1 by executing a program stored on a hard disk or the like (not shown).

[0045] Specifically, the CPU 33 moves the head unit 23 in the main scanning direction, ejects ink from the inkjet head 46 to print one pass, and then drives the take-up shaft 12 to move the printing medium 37 forward by one pass. Next, the CPU 33 moves the head unit 23 in the reverse direction, prints the next pass, and then moves the printing medium 37 forward by one pass. The CPU 33 prints an image on the printing medium 37 by alternately repeating this process of printing one pass and moving the printing medium 37.

[0046] During this printing operation, the CPU 33 controls the drying units 41A to 41N to heat and dry the printing medium 37 on which the ink has been ejected. In this case, the CPU 33 controls the amount of heating of the drying units 41A to 41N using the temperature of the printing medium 37 detected by the media temperature sensors 29A to 29N. Specifically, the CPU 33 controls the amount of heating of the platen heaters 18A to 18N of the drying units 41A to 41N using the temperature of the printing medium 37 detected by the media temperature sensors 29A to 29N. In addition, the CPU 33 controls the amount of heating of the fan heaters 52A to 52N of the drying units 41A to 41N using the temperature of the printing medium 37 detected by the media temperature sensors 29A to 29N.

[0047] Memory 34 stores the detected values ​​of the medium temperature sensors 29A to 29N, the heating amount of the platen heaters 18A to 18N, and the heating amount of the fan heaters 52A to 52N for each adjustment timing.

[0048] Next, the basic operation of the inkjet printing device 1 will be explained with reference to the flowchart in Figure 4.

[0049] The flowchart in Figure 4 is initiated when a print start command is issued via the operation panel 31, or when a print start command is issued from an external device such as a personal computer.

[0050] In step S1 of Figure 4, the CPU 33 turns on the platen heaters 18A to 18N and the fan heaters 52A to 52N. This starts the heating of the printing medium 37.

[0051] When heating of the printing medium 37 begins, the CPU 33 controls the heating amount of the platen heaters 18A to 18N and fan heaters 52A to 52N of the drying section 41A to 41N, based on the temperature of the printing medium 37 detected by the medium temperature sensors 29A to 29N, so that the temperature of the printing medium 37 reaches the target temperature. Details of this heating amount control of the drying section 41 will be described later.

[0052] After the heating of the printing medium 37 begins, in step S2, the CPU 33 determines whether the temperature of the printing medium 37 detected by each of the medium temperature sensors 29A to 29N has reached the target temperature. If the CPU 33 determines that there is at least one medium temperature sensor 29 in which the temperature of the printing medium 37 has not reached the target temperature (step S2: NO), the CPU 33 repeats step S2.

[0053] If all of the media temperature sensors 29A to 29N determine that the temperature of the printing medium 37 detected by each sensor has reached the target temperature (step S2: YES), then in step S3, the CPU 33 executes the printing operation.

[0054] When printing is complete, in step S4, the CPU 33 turns off the platen heaters 18A-18N and the fan heaters 52A-52N. This completes the series of operations.

[0055] Next, the printing operation of the inkjet printer 1 performed in step S3 of Figure 4 described above will be explained with reference to the flowchart in Figure 5.

[0056] In step S11 of Figure 5, the CPU 33 moves the printing medium 37 forward by one pass. This moves the printing medium 37 to the printing start position.

[0057] Next, in step S12, the CPU 33 receives print data for one pass from an external device.

[0058] Next, in step S13, the CPU 33 moves the head unit 23 from the left end to the right end of the main scanning drive guide 20, and ejects ink from the inkjet head 46 based on the print data received in step S12 to print on the printing medium 37. Before the start of the series of printing operations, the head unit 23 is initially positioned at the left end of the main scanning drive guide 20.

[0059] Next, in step S14, the CPU 33 determines whether or not print data remains.

[0060] If it is determined that there is still print data remaining (step S14: YES), in step S15, the CPU 33 moves the print medium 37 forward by one pass.

[0061] Next, in step S16, the CPU 33 receives print data for one pass from an external device.

[0062] Next, in step S17, the CPU 33 moves the head unit 23 from the right end to the left end of the main scanning drive guide 20, and ejects ink from the inkjet head 46 to print on the printing medium 37 based on the print data received in step S16.

[0063] Next, in step S18, the CPU 33 determines whether or not print data remains.

[0064] If the CPU determines that there is still print data remaining (step S18: YES), the CPU 33 returns to step S11 and moves the print medium 37 forward by one pass. After this, the CPU 33 proceeds to step S12.

[0065] If the CPU 33 determines in step S14 that there is no remaining print data (step S14: NO), and if the CPU 33 determines in step S18 that there is no remaining print data (step S18: NO), the series of operations ends.

[0066] Next, the control of the heating amount in the drying section 41 will be explained with reference to the flowcharts in Figures 6 to 8.

[0067] The flowcharts in Figures 6 to 8 represent the processing for one drying unit 41, and the flowcharts in Figures 6 to 8 are performed in parallel for each of the drying units 41A to 41N. As a result, the amount of heating for drying units 41A to 41N is controlled using the temperature of the printing medium 37 detected by the medium temperature sensors 29A to 29N, respectively.

[0068] The flowcharts in Figures 6 to 8 begin when the platen heater 18 and fan heater 52 are turned on in step S1 of Figure 4 described above.

[0069] In step S21 of Figure 6, the CPU 33 determines whether or not the platen heater 18 is on.

[0070] Here, the flowcharts in Figures 6 to 8 are executed continuously while the platen heater 18 and fan heater 52 are on, separate from the printing operation described in the flowchart in Figure 5. Therefore, in order to confirm whether the platen heater 18 and fan heater 52 are on, step S21 in Figure 6 determines whether the platen heater 18 is on or not.

[0071] As explained in the flowchart in Figure 4, the platen heater 18 and the fan heater 52 are switched on and off simultaneously. Therefore, in step S21, by determining whether the platen heater 18 is on or not, it is possible to determine whether both the platen heater 18 and the fan heater 52 are on or not. Alternatively, in step S21, it may be possible to determine whether the fan heater 52 is on or not.

[0072] If the CPU determines that the platen heater 18 is on (step S21: YES), in step S22, the CPU 33 determines whether or not it has received an adjustment timing signal from the timer 32. If it determines that it has not received an adjustment timing signal (step S22: NO), the CPU 33 returns to step S21.

[0073] If it is determined that an adjustment timing signal has been received (step S22: YES), in step S23, the CPU 33 obtains the detected values ​​from the head unit temperature sensor 25 and the ambient temperature sensor 30, respectively.

[0074] Next, in step S24, the CPU 33 obtains the detected value from the medium temperature sensor 29.

[0075] Next, in step S25, the CPU 33 determines whether the difference between the value detected by the media temperature sensor 29 and the value detected by the head unit temperature sensor 25 is less than or equal to a predetermined value.

[0076] The predetermined value mentioned above is a value such that the detected value of the media temperature sensor 29 and the detected value of the head unit temperature sensor 25 can be considered to be the same.

[0077] In the inkjet printer 1, during printing, the head unit 23 moves in the main scanning direction, causing the head unit 23 to pass between the media temperature sensors 29A to 29N and the printing medium 37. As a result, each of the media temperature sensors 29A to 29N experiences a non-detection period during which it cannot detect the temperature of the printing medium 37. For example, as shown in Figure 1, during the period when the head unit 23 adds position to the fan heater unit 26C, the presence of the head unit 23 between the media temperature sensor 29C and the printing medium 37 prevents the media temperature sensor 29C from detecting the temperature of the printing medium 37.

[0078] When the head unit 23 is located between the media temperature sensor 29 and the printing medium 37, the temperature detection target of the media temperature sensor 29 becomes the head unit 23, not the printing medium 37. Therefore, in this state, the detected value of the media temperature sensor 29 and the detected value of the head unit temperature sensor 25 become the same.

[0079] Therefore, in step S25, by determining whether the difference between the detected value of the media temperature sensor 29 and the detected value of the head unit temperature sensor 25 is less than or equal to the predetermined value mentioned above, it is possible to determine whether or not the head unit 23 is present between the media temperature sensor 29 and the printing medium 37.

[0080] If the CPU determines that the difference between the value detected by the media temperature sensor 29 and the value detected by the head unit temperature sensor 25 exceeds a predetermined value (step S25: NO), in step S26, the CPU 33 associates the adjustment timing number indicating the current adjustment timing with the value detected by the media temperature sensor 29 obtained in step S24 and stores it in the memory 34.

[0081] In this case, if the difference between the value detected by the media temperature sensor 29 and the value detected by the head unit temperature sensor 25 exceeds a predetermined value, it means that the value detected by the media temperature sensor 29 is the temperature of the printing medium 37.

[0082] Next, in step S27, the CPU 33 calculates the heating amounts for the platen heater 18 and the fan heater 52, and sets the calculated heating amounts to the platen heater driver 19 and the fan heater driver 28. The CPU 33 also stores the calculated heating amounts for the platen heater 18 and the fan heater 52 in the memory 34.

[0083] Specifically, the CPU 33 calculates the amount of heating required for the platen heater 18 and fan heater 52 to bring the temperature of the printing medium 37 closer to the target temperature, based on the temperature of the printing medium 37 detected by the medium temperature sensor 29, the type of ink used by the head unit 23, the type of printing medium 37, and the ambient temperature detected by the ambient temperature sensor 30.

[0084] The CPU 33 then sets the calculated heating amounts for the platen heater 18 and fan heater 52 to the platen heater driver 19 and fan heater driver 28, respectively. This adjusts the heating amounts for the platen heater 18 and fan heater 52 to the values ​​calculated as described above. The CPU 33 also stores the calculated heating amounts for the platen heater 18 and fan heater 52 in the memory 34, associating them with the current adjustment timing number and the detected value of the medium temperature sensor 29.

[0085] After this, CPU33 returns to step S21 and repeats the subsequent processing.

[0086] Here, when the inkjet printer 1 is instructed to start printing and the platen heater 18 and fan heater 52 are turned on, the processes described in steps S21 to S27 above are repeated, and the printing medium 37 is heated until it reaches the target temperature, as shown in Figure 9. In Figure 9, time ta is the timing when the printer is instructed to start printing, and at that time the printing medium 37 is at the same temperature as room temperature.

[0087] Furthermore, during the period from when the platen heater 18 and fan heater 52 are turned on until the printing medium 37 reaches the target temperature, the printing operation has not yet started, so the head unit 23 is not present between the medium temperature sensor 29 and the printing medium 37. For this reason, during this period, step S25 in Figure 6 is judged as "NO".

[0088] After the printing medium 37 reaches the target temperature, the heating amount of the platen heater 18 and the fan heater 52 is controlled by the processes of steps S21 to S27 in Figure 6 described above, so that the printing medium 37 maintains the target temperature, as shown in Figure 9.

[0089] After the printing medium 37 reaches the target temperature, the heating amount of the platen heater 18 and fan heater 52 is basically the same control that is repeated. That is, when the temperature of the printing medium 37 falls below the target temperature, the heating amount of the platen heater 18 and fan heater 52 is slightly increased, and when it rises above the target temperature, the heating amount is slightly decreased, and this control is repeated.

[0090] Over a long period, the amount of heating provided by the platen heater 18 and fan heater 52 relative to the temperature of the printing medium 37 changes in response to changes in ambient temperature. Specifically, when the ambient temperature decreases, the amount of heating provided by the platen heater 18 and fan heater 52 when the temperature of the printing medium 37 falls below the target temperature increases slightly, and when the ambient temperature increases, the amount of heating provided by the platen heater 18 and fan heater 52 when the temperature of the printing medium 37 rises above the target temperature decreases slightly. However, over a short period where there is no change in ambient temperature, the increase and decrease in the amount of heating provided by the platen heater 18 and fan heater 52 both repeat periodically by the same amount.

[0091] Now, once the printing medium 37 reaches the target temperature and printing begins, as mentioned above, the presence of the head unit 23 between the medium temperature sensor 29 and the printing medium 37 results in a non-detection period during which the medium temperature sensor 29 cannot detect the temperature of the printing medium 37.

[0092] During the non-detection period, as mentioned above, the detected value of the media temperature sensor 29 and the detected value of the head unit temperature sensor 25 are the same. Therefore, in step S25 of Figure 6, the CPU 33 determines that the difference between the detected value of the media temperature sensor 29 and the detected value of the head unit temperature sensor 25 is less than or equal to a predetermined value (step S25: YES), and proceeds to step S28 of Figure 7.

[0093] Here, the undetected period is a short period during which changes in the ambient temperature can be ignored. Therefore, during the undetected period when the respective medium temperature sensors 29A to 29N corresponding to each of the drying units 41A to 41N cannot detect the temperature of the printing medium 37, as will be described below, based on the control history of the heating amount (heating amounts of the platen heater 18 and the fan heater 52) of the drying unit 41 before the undetected period, the heating amount of the drying unit 41 is controlled.

[0094] In step S28 of FIG. 7, when the CPU 33 assumes that the current adjustment timing is the adjustment timing of adjustment timing number t(k + 1), it determines whether the detected value T(k - 1) of the medium temperature sensor 29 at the adjustment timing of adjustment timing number t(k - 1) is smaller than the detected value T(k) of the medium temperature sensor 29 at the adjustment timing of adjustment timing number t(k).

[0095] In the following description, the adjustment timings of adjustment timing numbers t(k), t(k + 1),... may be expressed as adjustment timings t(k), t(k + 1),...

[0096] The adjustment timing t(k + 1) is the first adjustment timing during the undetected period, and the adjustment timing t(k) is the adjustment timing immediately before the undetected period.

[0097] If it is determined that T(k - 1) < T(k) (step S28: YES), in step S29, the CPU 33 sets "2" to the variable m.

[0098] Next, in step S30, the CPU 33 determines whether T(k - m) = T(k) and T(k - m - 1) < T(k - m).

[0099] It is assumed that T(k - m) = T(k) is determined not only when T(k - m) and T(k) are exactly equal, but also when there is a slight difference within a range that can be regarded as equal.

[0100] If it is determined that T(k - m) ≠ T(k) or T(k - m - 1) ≥ T(k - m) (step S30: NO), in step S31, the CPU 33 adds "1" to the variable m. After that, the CPU 33 returns to step S30.

[0101] In step S30, if it is determined that T(k - m) = T(k) and T(k - m - 1) < T(k - m) (step S30: YES), the CPU 33 proceeds to step S35 in FIG. 8.

[0102] In step S28, if it is determined that T(k - 1) ≥ T(k) (step S28: NO), in step S32, the CPU 33 sets the variable m to "2".

[0103] Next, in step S33, the CPU 33 determines whether T(k - m) = T(k) and T(k - m - 1) ≥ T(k - m).

[0104] If it is determined that T(k - m) ≠ T(k) or T(k - m - 1) < T(k - m) (step S33: NO), in step S34, the CPU 33 adds "1" to the variable m. After that, the CPU 33 returns to step S33.

[0105] In step S33, if it is determined that T(k - m) = T(k) and T(k - m - 1) ≥ T(k - m) (step S33: YES), the CPU 33 proceeds to step S35 in FIG. 8.

[0106] Through the processing of steps S28 to S34 in FIG. 7 described above, the CPU 33 detects the adjustment timing that is closest to the adjustment timing t(k) among the adjustment timings before the adjustment timing t(k), where the temperature condition of the printing medium 37 is the same as the adjustment timing t(k) immediately before the non - detection period.

[0107] Here, the temperature conditions of the printing medium 37 are indicated by the temperature of the printing medium 37 detected by the medium temperature sensor 29 and the direction of change in the temperature of the printing medium 37. The direction of change in the temperature of the printing medium 37 means whether the temperature of the printing medium 37 has changed upward, remained constant, or changed downward since the last adjustment timing.

[0108] If, at two adjustment timings, the temperature of the printing medium 37 and the direction of change of the temperature of the printing medium 37 are the same, then the temperature conditions of the printing medium 37 are the same at these two adjustment timings.

[0109] At each adjustment timing up to adjustment timing t(k), the temperature of the printing medium 37 detected by the medium temperature sensor 29 is stored in the memory 34 in association with the adjustment timing number, as shown in Figure 10, through the process of step S26 in Figure 6 described above.

[0110] Furthermore, as shown in Figure 10, the memory 34 also stores the heating amounts of the platen heater 18 and the fan heater 52, associated with the adjustment timing number and the temperature of the printing medium 37 detected by the medium temperature sensor 29, through the process of step S27 in Figure 6 described above. In other words, the memory 34 stores the control history of the heating amounts of the drying unit 41 (platen heater 18 and fan heater 52).

[0111] If T(k-1) < T(k) (step S28: YES), then the direction of temperature change of the printing medium 37 at adjustment timing t(k) from the previous adjustment timing t(k-1) is upward. In this case, the CPU 33 searches for an adjustment timing with the same temperature conditions as adjustment timing t(k) by going back one adjustment timing in the past from adjustment timing t(k) by processing in steps S29 to S31.

[0112] Here, in order to find an adjustment timing with the same temperature conditions as adjustment timing t(k), the CPU 33 first searches for an adjustment timing in which the detected value of the medium temperature sensor 29 is the same as adjustment timing t(k).

[0113] For this purpose, in the process of step S30, the CPU 33 checks the detected values T(k-m+1), T(k-m), and T(k-m-1) of three consecutive adjustment timings t(k-m+1), t(k-m), and t(k-m-1). Then, when T(k-m+1) < T(k-m) < T(k-m-1) and T(k-m+1) < T(k), T(k-m) = T(k), T(k) < T(k-m-1), or when T(k-m-1) < T(k-m) < T(k-m+1) and T(k-m-1) < T(k), T(k-m) = T(k), T(k) < T(k-m+1), the adjustment timing t(k-m) is positioned as the adjustment timing at which the detected value of the medium temperature sensor 29 is the same as the adjustment timing t(k).

[0114] Next, the CPU 33 determines whether T(k-m-1) < T(k-m). When the CPU 33 determines that T(k-m-1) < T(k-m), the determination in step S30 becomes "YES". As a result, the CPU 33 determines that the adjustment timing t(k-m) is the adjustment timing closest to the adjustment timing t(k) among the adjustment timings under the same temperature condition as the adjustment timing t(k).

[0115] Also, when T(k-1) ≥ T(k) (step S28: NO), the change direction of the temperature of the print medium 37 from the previous adjustment timing t(k-1) at the adjustment timing t(k) is horizontal or downward. In this case, the CPU 33 searches for the adjustment timing under the same temperature condition as the adjustment timing t(k) while tracing back the adjustment timing one by one from the adjustment timing t(k) through the processes of steps S32 to S34.

[0116] In the process of step S33, in the same manner as the process of step S30, the adjustment timing when the detected value of the medium temperature sensor 29 is the same as the adjustment timing t(k) is searched for. Then, when the adjustment timing t(k-m) is positioned as the adjustment timing when the detected value of the medium temperature sensor 29 is the same as the adjustment timing t(k), the CPU 33 determines whether T(k-m-1)≥T(k-m). When the CPU 33 determines that T(k-m-1)≥T(k-m), the determination in step S33 becomes "YES". As a result, the CPU 33 determines that the adjustment timing t(k-m) is the adjustment timing closest to the adjustment timing t(k) among the adjustment timings under the same temperature condition as the adjustment timing t(k).

[0117] Here, for example, it is assumed that the temperature (detected value) of the printing medium 37 detected by the medium temperature sensor 29 has changed as shown in FIG. 11 up to the adjustment timing t(k). In FIG. 11, the change direction of the temperature of the printing medium 37 at each adjustment timing is indicated by "↑" when it is the rising direction, and "↓" when it is the horizontal or falling direction.

[0118] In the example of FIG. 11, when tracing back from the adjustment timing t(k), first, the detected value (temperature of the printing medium 37) T4 (see FIG. 10) at the adjustment timing t(k-4) is the same as the detected value T0 at the adjustment timing t(k).

[0119] Here, among the detected values T3, T4, and T5 at the three consecutive adjustment timings t(k-3), t(k-4), and t(k-5), T3<T4<T5, and T3<T0, T4=T0, T0<T5. From this, the adjustment timing t(k-4) is positioned as the adjustment timing when the temperature of the printing medium 37 is the same as the adjustment timing t(k). [[ID=I4]]

[0120] However, the adjustment timing t(k-4) and the adjustment timing t(k) have different change directions of the temperature of the printing medium 37. Therefore, the adjustment timing t(k-4) has a different temperature condition from the adjustment timing t(k).

[0121] Therefore, when tracing further back from the adjustment timing t(k - 4), as shown in FIG. 11, the detected value T8 at the adjustment timing t(k - 8) is the same as the detected value T0 at the adjustment timing t(k).

[0122] Here, among the detected values T7, T8, and T9 at three consecutive adjustment timings t(k - 7), t(k - 8), and t(k - 9) respectively, T9 < T8 < T7, and T9 < T0, T8 = T0, T0 < T7. From this, the adjustment timing t(k - 8) is positioned as the adjustment timing when the temperature of the printing medium 37 is the same as that at the adjustment timing t(k).

[0123] And the change direction of the temperature of the printing medium 37 at the adjustment timing t(k - 8) is the same as that at the adjustment timing t(k). For this reason, it is determined that the adjustment timing t(k - 8) is the adjustment timing closest to the adjustment timing t(k) among the adjustment timings with the same temperature condition as the adjustment timing t(k).

[0124] Returning to FIG. 8, in step S35, the CPU 33 sets the value of m - 1 to the variable s.

[0125] Next, in step S36, the CPU 33 sets the heating amount P(s) of the platen heater 18 to the platen heater driver 19 and sets the heating amount W(s) of the fan heater 52 to the fan heater driver 28. Thereby, the heating amounts of the platen heater 18 and the fan heater 52 are adjusted to be P(s) and W(s) respectively.

[0126] Here, when s = m - 1, P(s) and W(s) respectively correspond to the heating amount P(m - 1) of the platen heater 18 and the heating amount W(m - 1) of the fan heater 52 at the adjustment timing t(k - m - 1).

[0127] Also, in step S36, the CPU 33 stores the heating amount P(s) of the platen heater 18 and the heating amount W(s) of the fan heater 52 in the memory 34 in association with the current adjustment timing number.

[0128] At this time, the CPU 33 stores the temperature T(s) of the printing medium 37 in memory 34, associating it with the current adjustment timing number, the heating amount P(s) of the platen heater 18, and the heating amount W(s) of the fan heater 52. Here, the temperature T(s) of the printing medium 37 is stored as the same value as T(m-1).

[0129] Next, in step S37, the CPU 33 determines whether or not it has received an adjustment timing signal from the timer 32. If it determines that it has not received an adjustment timing signal (step S37: NO), the CPU 33 repeats step S37.

[0130] If it is determined that an adjustment timing signal has been received (step S37: YES), in step S38, the CPU 33 obtains the detected value from the medium temperature sensor 29.

[0131] Next, in step S39, the CPU 33 determines whether the difference between the value detected by the media temperature sensor 29 and the value detected by the head unit temperature sensor 25 is less than or equal to the predetermined value mentioned above.

[0132] If the CPU determines that the difference between the value detected by the media temperature sensor 29 and the value detected by the head unit temperature sensor 25 is less than or equal to a predetermined value (step S39: YES), in step S40, the CPU 33 determines whether the variable s = 0. If it determines that s = 0 (step S40: YES), the CPU 33 returns to step S35.

[0133] If it is determined that s is not 0 (step S40: NO), the CPU 33 subtracts "1" from the variable s in step S41. After this, the CPU 33 returns to step S36.

[0134] As a result of the processing in steps S35 to S41 described above, the CPU 33 controls the amount of heating of the drying section 41 during the non-detection period in the same way as the heating control performed between the adjustment timing immediately preceding adjustment timing t(k) and the adjustment timing t(k), where the temperature conditions of the printing medium 37 are the same as those of the adjustment timing t(k) immediately preceding the non-detection period.

[0135] In other words, when the adjustment timing t(km) is detected by the processing in steps S28 to S34 as the adjustment timing closest to adjustment timing t(k) among the adjustment timings with the same temperature conditions as adjustment timing t(k), the variable s is set to the value of m-1 in step S35, and the heating amounts P(s) and W(s) are set for the platen heater driver 19 and the fan heater driver 28 respectively in step S36, thereby adjusting the heating amounts of the platen heater 18 and the fan heater 52 at adjustment timing t(k+1) to the same values ​​as the heating amounts at the next adjustment timing t(km-1) after adjustment timing t(km).

[0136] Subsequently, through the processing in steps S37 to S41, as long as the non-detection period continues, the heating amounts set in the platen heater driver 19 and the fan heater driver 28 are sequentially changed to the respective heating amounts at adjustment timings t(km-2), t(km-3), ... each time an adjustment timing occurs.

[0137] First, in step S35, the variable s is set to a value of m-1. Then, steps S36 to S41 are repeated until the variable s becomes 0 (step S40: YES). This allows the same control to be performed at adjustment timings t(k+1) to t(k+m) as the control of the heating amount of the drying section 41 performed at adjustment timings t(km-1) to t(k).

[0138] Here, when the variable s=0, it means that the heating amounts P(s) and W(s) become the heating amounts P0 and W0 at the adjustment timing t(k) immediately preceding the non-detection period. Therefore, when the variable s=0 (step S40:YES), the process returns to step S35 and the value m-1 is set for the variable s. After this, if the non-detection period continues, steps S36 to S41 are repeated until the variable s=0 again, performing the same control as the control of the heating amount of the drying section 41 performed at adjustment timings t(km-1) to t(k).

[0139] In this way, during the non-detection period, the same control as the control of the heating amount of the drying section 41 that was performed at adjustment timings t(km-1) to t(k) is repeatedly performed.

[0140] In the example shown in Figure 11, the temperature conditions of the printing medium 37 are the same as those of the adjustment timing t(k) immediately preceding the non-detection period. Of the adjustment timings prior to adjustment timing t(k), the adjustment timing closest to adjustment timing t(k) is, as mentioned above, adjustment timing t(k-8). Therefore, as shown in Figures 11 and 12, the same control is performed at adjustment timings t(k+1) to t(k+8) as the control of the heating amount of the drying section 41 performed between adjustment timing t(k-7) and adjustment timing t(k). If the non-detection period continues after adjustment timing t(k+8), the same control is repeated as the control of the heating amount of the drying section 41 performed at adjustment timings t(k-7) to t(k).

[0141] Now, when the head unit 23 passes between the media temperature sensor 29 and the printing medium 37 and the non-detection period ends, the detected value of the media temperature sensor 29 and the detected value of the head unit temperature sensor 25 become different values.

[0142] In this case, in step S39 of Figure 7, the CPU 33 determines that the difference between the value detected by the media temperature sensor 29 and the value detected by the head unit temperature sensor 25 is less than or equal to a predetermined value (step S39: NO). In this case, the CPU 33 proceeds to step S26 of Figure 6. This returns to controlling the amount of heating of the drying section 41 when the head unit 23 is not present between the media temperature sensor 29 and the printing medium 37.

[0143] If the CPU 33 determines in step S21 that the platen heater 18 is off (step S21: NO), the series of processes ends.

[0144] As described above, the inkjet printing apparatus 1 is equipped with media temperature sensors 29A to 29N, each corresponding to a drying section 41A to 41N, which detect the temperature of the printing medium 37 in the area heated by the drying sections 41A to 41N. The CPU 33 controls the amount of heating of the drying sections 41A to 41N using the temperature of the printing medium 37 detected by the media temperature sensors 29A to 29N. This reduces insufficient drying and uneven drying of the printing medium 37, and reduces the deterioration of print quality, compared to a configuration where the temperature sensors for detecting the temperature of the printing medium 37 are placed on the carriage 47.

[0145] Furthermore, in the inkjet printing apparatus 1, the CPU 33 controls the heating amount of the drying unit 41 based on the heating amount control history of the drying unit 41 during non-detection periods when the corresponding media temperature sensors 29A to 29N in each of the drying units 41A to 41N cannot detect the temperature of the printing medium 37. This reduces the deviation of the temperature of the printing medium 37 from the target temperature, even during non-detection periods.

[0146] Furthermore, in the inkjet printing apparatus 1, the CPU 33 controls the heating amount of each drying section 41A to 41N during the non-detection period by performing the same heating amount control as performed between the adjustment timing immediately preceding adjustment timing t(k) and adjustment timing t(k), where the temperature conditions of the printing medium 37 are the same as those of the adjustment timing t(k) immediately preceding the non-detection period. This allows for good adjustment of the heating amount during the non-detection period based on the control history of the heating amount of the drying section 41.

[0147] Furthermore, in the inkjet printer 1, the CPU 33 determines that a head unit 23 is present between the medium temperature sensor 29 and the printing medium 37 when the difference between the detected value of the medium temperature sensor 29 and the detected value of the head unit temperature sensor 25 is less than or equal to a predetermined value. This allows for the detection of a state in which a head unit 23 is present between the medium temperature sensor 29 and the printing medium 37, preventing the medium temperature sensor 29 from detecting the temperature of the printing medium 37, with a simple configuration.

[0148] Furthermore, a linear encoder may be used to detect the presence of the head unit 23 between the media temperature sensor 29 and the printing medium 37.

[0149] In this case, as shown in Figures 13 and 14, a linear scale 61 is positioned on the main scanning drive guide 20. A sensor 62 is also positioned on the head unit 23. The linear scale 61 and sensor 62 constitute a linear encoder.

[0150] The linear scale 61 has a scale formed by multiple slits. The sensor 62 reads the scale on the linear scale 61 and outputs position information indicating the position of the sensor 62.

[0151] In Figure 13, the head unit 23 is positioned at its initial location at the left end of the main scanning drive guide 20. At this time, the sensor 62 is at position X=0 in the X direction (left-right direction). Let HU1 be the distance from the X=0 position to the right end of the head unit 23, and HU2 be the distance to the left end.

[0152] Furthermore, the positions of the media temperature sensors 29A, 29B, 29C, ... are defined as X = X1, X2, X3, ... respectively.

[0153] When the sensor 62 is in the interval from X=Xi-HU1 to X=Xi+HU2 (i=1,2,3,…), the head unit 23 is located between the medium temperature sensor 29 at position Xi and the printing medium 37.

[0154] When using the linear encoder described above, the CPU 33 acquires position information from the sensor 62 while the head unit 23 is moving. Based on the acquired position information and the values ​​of HU1, HU2, X1, X2, X3, ... described above, the CPU 33 determines whether or not the head unit 23 is present between the medium temperature sensor 29 and the printing medium 37.

[0155] Furthermore, a reflective optical sensor may be used to detect the presence of the head unit 23 between the medium temperature sensor 29 and the printing medium 37.

[0156] In this case, as shown in Figures 15 and 16, a reflector 71 is positioned on the head unit 23. The reflector 71 extends along the entire length of the head unit 23 in the left-right direction.

[0157] Furthermore, reflective optical sensors 72A, 72B, 72C, ... corresponding to the medium temperature sensors 29A, 29B, 29C, ... are arranged on the main scanning drive guide 20. Sensors 72A, 72B, 72C, ... are positioned in the same locations as the medium temperature sensors 29A, 29B, 29C, ... in the left-right direction.

[0158] The sensor 72 has a light-emitting unit and a light-receiving unit (neither of which are shown). The sensor 72 detects the reflector 71 by receiving the light reflected by the reflector 71 from the light-emitting unit.

[0159] When the CPU 33 detects the reflector 71 with the sensor 72, it determines that the head unit 23 is located between the medium temperature sensor 29 corresponding to the sensor 72 and the printing medium 37.

[0160] Furthermore, a transmissive optical sensor may be used to detect the presence of the head unit 23 between the medium temperature sensor 29 and the printing medium 37.

[0161] In this case, as shown in Figures 17 and 18, a shielding plate 81 is erected on the head unit 23. The shielding plate 81 extends along the entire length of the head unit 23 in the left-right direction.

[0162] Furthermore, sensors 82A, 82B, 82C, ... which are transmissive optical sensors corresponding to the medium temperature sensors 29A, 29B, 29C, ... are arranged on the main scanning drive guide 20. Sensors 82A, 82B, 82C, ... are positioned in the same locations as the medium temperature sensors 29A, 29B, 29C, ... in the left-right direction.

[0163] Sensor 82 has a light-emitting unit and a light-receiving unit (neither of which are shown) that are arranged facing each other. Sensor 82 detects the shielding plate 81 when the light from the light-emitting unit is blocked by the shielding plate 81 that passes between the light-emitting unit and the light-receiving unit, preventing the light from being received by the light-receiving unit.

[0164] When the CPU 33 detects the shielding plate 81 with the sensor 82, it determines that the head unit 23 is located between the medium temperature sensor 29 corresponding to the sensor 82 and the printing medium 37.

[0165] Furthermore, in the above-described embodiment, the amount of heating of the drying section 41 during the non-detection period was controlled based on the control history prior to the non-detection period, but this is not limited to this. For example, heating by the drying section 41 may be suspended during the non-detection period.

[0166] Furthermore, the content of the heating amount control based on the heating amount control history of the drying unit 41 is not limited to that in the embodiment described above. For example, during the non-detection period, the heating amount at the adjustment timing immediately preceding the non-detection period may be continuously set for the drying unit 41.

[0167] Furthermore, although the above-described embodiment shows a configuration in which the drying section 41 includes a platen heater 18 and a fan heater unit 26, a configuration in which either of these is omitted is also possible.

[0168] Furthermore, although the above-described embodiment shows a configuration in which the head unit 23 moves between the medium temperature sensor 29 and the printing medium 37, the head unit may also be configured to move without passing between the medium temperature sensor and the printing medium.

[0169] The present invention is not limited to the embodiments described above, and the components can be modified and implemented in practice without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the embodiments. For example, some components may be deleted from all the components shown in the embodiments.

[0170] [Note] This application discloses the following invention:

[0171] (Note 1) An inkjet head that moves in a predetermined direction and ejects ink onto a printing medium to print, Multiple drying units arranged along the predetermined direction for heating and drying the printing medium, A plurality of media temperature detection units are provided corresponding to each of the plurality of drying units, and each of the media temperature detection units detects the temperature of the printing medium in the region heated by the corresponding drying unit. A control unit controls the amount of heating in each of the multiple drying sections using the temperature of the printing medium detected by the corresponding medium temperature detection unit. An inkjet printing apparatus characterized by comprising the following features.

[0172] (Note 2) The inkjet head is provided in a head unit that moves in a predetermined direction between the plurality of media temperature detection units and the printing medium. The inkjet printing apparatus according to Appendix 1, characterized in that the control unit controls the amount of heating of each of the plurality of drying units based on the heating amount control history of the drying unit during a non-detection period in which the media temperature detection unit cannot detect the temperature of the printing medium due to the presence of the head unit between the media temperature detection unit corresponding to the drying unit and the printing medium.

[0173] (Note 3) The control unit, For each of the aforementioned plurality of drying sections, the temperature of the printing medium detected by the media temperature detection section corresponding to that drying section is acquired at predetermined time intervals, and the amount of heating of the drying section is controlled based on the acquired temperature of the printing medium. The inkjet printing apparatus according to Appendix 2, characterized in that, for each of the plurality of drying sections, as control of the amount of heating of the drying section during the non-detection period, the same control as the control of the amount of heating performed between the adjustment timing immediately preceding the adjustment timing, which is the adjustment timing closest to the immediate preceding adjustment timing, and which is the same as the adjustment timing immediately preceding the adjustment timing, as the temperature conditions indicated by the temperature of the printing medium detected by the medium temperature detection section corresponding to the drying section and the direction of change of the temperature of the printing medium.

[0174] (Note 4) The head unit temperature detection unit further includes a head unit temperature detection unit for detecting the temperature of the head unit, The inkjet printing apparatus according to Appendix 2 or 3, characterized in that the control unit determines that the head unit is present between the media temperature detection unit and the printing medium when the difference between the detected value of the media temperature detection unit and the detected value of the head unit temperature detection unit in each of the plurality of media temperature detection units is less than or equal to a predetermined value. [Explanation of symbols]

[0175] 1. Inkjet printing device 11. Print media roll support shaft 12 reel spindles 13. Winding drive motor 14. Winding drive motor driver 15,16 Print Media Guide 17, 17A~17N Platen 18, 18A~18N Platen Heater 19, 19A~19N Platen Heater Driver 20 Main scanning drive guide 21 Main scanning drive motor 22 Main scanning drive motor driver 23 Head Unit 24 Head drive unit 25 Head unit temperature sensor 26, 26A~26N Fan Heater Unit 27, 27A~27N Blower fan driver 28, 28A~28N Fan Heater Driver 29, 29A~29N Medium Temperature Sensor 30 Ambient temperature sensor 31 Control Panel 32 timers 33 CPU 34 memory 36 Print media rolls 37 Print media 41,41A~41N Drying section 46 inkjet heads 47 Carriage 51, 51A~51N Blower fan 52, 52A~52N Fan Heater 53, 53A~53N Duct

Claims

1. An inkjet head that moves in a predetermined direction and ejects ink onto a printing medium to print, Multiple drying units arranged along the predetermined direction for heating and drying the printing medium, A plurality of media temperature detection units are provided corresponding to each of the plurality of drying units, and each of the media temperature detection units detects the temperature of the printing medium in the region heated by the corresponding drying unit. A control unit controls the amount of heating in each of the multiple drying sections using the temperature of the printing medium detected by the corresponding medium temperature detection unit. An inkjet printing apparatus characterized by comprising the following features.

2. The inkjet head is provided in a head unit that moves in a predetermined direction between the plurality of media temperature detection units and the printing medium. The inkjet printing apparatus according to claim 1, characterized in that the control unit controls the amount of heating of the drying unit based on the heating amount control history of the drying unit during a non-detection period in each of the plurality of drying units in which the media temperature detection unit cannot detect the temperature of the printing medium due to the presence of the head unit between the media temperature detection unit corresponding to the drying unit and the printing medium.

3. The control unit, For each of the aforementioned plurality of drying sections, the temperature of the printing medium detected by the media temperature detection section corresponding to that drying section is acquired at predetermined time intervals, and the amount of heating of the drying section is controlled based on the acquired temperature of the printing medium. The inkjet printing apparatus according to claim 2, characterized in that, for each of the plurality of drying sections, as control of the amount of heating of the drying section during the non-detection period, the same control as the control of the amount of heating performed between the adjustment timing immediately preceding the adjustment timing, which is the same as the adjustment timing immediately preceding the adjustment timing, where the temperature conditions indicated by the temperature of the printing medium detected by the medium temperature detection section corresponding to the drying section and the direction of change of the temperature of the printing medium are the same as the adjustment timing immediately preceding the non-detection period.

4. The head unit temperature detection unit further includes a head unit temperature detection unit for detecting the temperature of the head unit, The inkjet printing apparatus according to claim 2 or 3, characterized in that the control unit determines that the head unit is present between the media temperature detection unit and the printing medium when the difference between the detected value of the media temperature detection unit and the detected value of the head unit temperature detection unit in each of the plurality of media temperature detection units is less than or equal to a predetermined value.

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