JP2024033673A - Inkjet recording device, ink temperature control method and program - Google Patents

Abstract

To provide an inkjet recording device, an ink temperature control method and a program which can prevent unevenness from occurring in the quality and glossiness of a formed image.SOLUTION: An inkjet recording device 1 is provided with inkjet heads 241 that discharge ink from a nozzle opening part 242 to a recording medium P to record an image on the medium, an adjusting part 246 that adjusts a temperature of ink discharged from the nozzle opening part 242, and a control part 40 that controls the adjusting part 246. The inkjet heads 241 are arranged in a plurality of rows along a conveying direction of the recording medium. The control part 40 controls the adjusting part 246 so that a temperature of ink discharged from a first inkjet head 241a is higher than a temperature of ink discharged from a second inkjet head 241b arranged closer to an upstream side in a conveying direction than the first inkjet head 241a.SELECTED DRAWING: Figure 1

Description

The present invention relates to an inkjet recording apparatus, an ink temperature control method, and a program.

2. Description of the Related Art Inkjet recording apparatuses that include a plurality of head units are conventionally known. Each head unit includes multiple inkjet heads. An inkjet recording apparatus discharges ink of each color from each head unit, and causes the ink to land at a desired position on a recording medium that is conveyed in a predetermined conveyance direction.

Such an inkjet recording apparatus emits energy rays, such as ultraviolet rays, on the downstream side in the transport direction from the ink ejection position of the head unit. The ink that is irradiated with energy rays is cured. This fixes the ink onto the recording medium.

On the other hand, the ink does not harden until it is irradiated with energy rays. Therefore, as shown in FIGS. 7A and 7B, as time passes after the ink lands, the ink spreads on the recording medium and becomes flat. When the ink becomes flat, the gloss level increases. Further, the upstream head unit provided on the upstream side in the transport direction is further away from the energy beam injection device than the downstream head unit provided on the downstream side in the transport direction. Therefore, it takes more time for the upstream head unit than for the downstream head unit from the time the ink lands until the energy beam is irradiated.

Therefore, the ink wets and spreads more in the portion recorded by the upstream head unit than in the portion recorded by the downstream head unit before being irradiated with the energy beam. Then, the portion recorded by the upstream head unit has higher gloss than the portion recorded by the downstream head unit. As a result, there was a problem in that the quality and gloss of the image were uneven.

Therefore, in an inkjet recording apparatus using inks of a plurality of colors, an invention is known in which the ink of a color ejected from a head unit on the upstream side has a higher phase transition temperature (see, for example, Patent Document 1). As a result, the ink of each color spreads substantially uniformly. Therefore, it is possible to prevent unevenness in image quality and gloss among head units.

Japanese Patent Application Publication No. 2012-121288

However, as shown in FIG. 8, the ink wets and spreads more in the recording area of the inkjet head on the upstream side than in the recording area of the downstream inkjet head in the head unit of the same color. This poses a problem in that the image quality and gloss of the image formed on the recording medium are uneven. This problem cannot be solved by the invention described in Patent Document 1.

In order to solve this problem, the present invention aims to provide an inkjet recording apparatus, an ink temperature control method, and a program that are less likely to cause unevenness in the quality and gloss of formed images.

The invention according to claim 1 is an inkjet recording device, comprising:
an inkjet head that records an image by ejecting ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium;
an adjustment unit that adjusts the temperature of the ink discharged from the nozzle opening;
A control unit that controls the adjustment unit,
A plurality of the inkjet heads are arranged along the conveyance direction of the recording medium,
The control unit is configured such that the temperature of the ink ejected from a first inkjet head among the plurality of inkjet heads is such that the ink is ejected from a second inkjet head disposed upstream of the first inkjet head in the transport direction. The adjustment unit is controlled so that the temperature is higher than the temperature of the ink.

The invention according to claim 2 is the inkjet recording apparatus according to claim 1,
The ink ejected from each inkjet head has the same color.

The invention according to claim 3 is an inkjet recording apparatus according to claim 1 or 2,
The control section controls the adjustment section so that the temperature of the first inkjet head is higher than the temperature of the second inkjet head.

The invention according to claim 4 is an inkjet recording apparatus according to claim 1 or 2,
an ink storage section in which the ink is stored;
a plurality of ink supply channels that respectively supply the ink stored in the ink storage section to a plurality of inkjet heads;
The control unit controls the adjustment unit so that the temperature of the ink supply channel communicating with the first inkjet head is higher than the temperature of the ink supply channel communicating with the second inkjet head. Control.

The invention according to claim 5 is an inkjet recording apparatus according to claim 1 or 2,
Equipped with an acquisition unit that acquires image information,
The control unit determines whether or not to control the adjustment unit based on information on the image acquired by the acquisition unit.

The invention according to claim 6 is the inkjet recording apparatus according to claim 5,
The control unit controls the adjustment unit when determining that the image includes a photograph based on the information on the image acquired by the acquisition unit.

The invention according to claim 7 is the inkjet recording apparatus according to claim 1,
Equipped with a head unit,
The head unit includes the first inkjet head and the second inkjet head.

The invention according to claim 8 is:
an inkjet head that records an image by ejecting ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium;
an adjustment unit that adjusts the temperature of the ink discharged from the nozzle opening;
A control unit that controls the adjustment unit,
An ink temperature control method in an inkjet recording apparatus in which a plurality of the inkjet heads are arranged along the conveyance direction of a recording medium,
The temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is the same as that of the ink ejected from the second inkjet head disposed upstream of the first inkjet head in the transport direction. The adjustment section is controlled so that the temperature is higher than the temperature.

The invention according to claim 9 is a program,
an inkjet head that records an image by ejecting ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium;
an adjustment unit that adjusts the temperature of the ink discharged from the nozzle opening,
A computer provided in an inkjet recording apparatus in which a plurality of the inkjet heads are arranged along the conveyance direction of the recording medium functions as a control unit that controls the adjustment unit,
The control unit is configured to control the temperature of the ink ejected from a first inkjet head among the plurality of inkjet heads, such that the ink ejected from a second inkjet head disposed upstream of the first inkjet head in the transport direction. The adjustment unit is controlled so that the temperature is higher than the temperature of the ink.

According to the present invention, it is possible to provide an inkjet recording apparatus, an ink temperature control method, and a program that are less likely to cause unevenness in the image quality or gloss of formed images.

FIG. 1 is a schematic cross-sectional view of an inkjet recording device. FIG. 1 is a block diagram of an inkjet recording device. FIG. 3 is a bottom view showing the configuration of the head unit. FIG. 2 is a schematic diagram illustrating a configuration related to an ink supply path between an ink storage section and an inkjet head. 5 is a flowchart showing ink temperature control in the inkjet recording apparatus according to the first embodiment. 7 is a flowchart showing ink temperature control in an inkjet recording apparatus according to a second embodiment. FIG. 3 is an enlarged side view of ink immediately after it has landed on a recording medium. FIG. 3 is an enlarged side view of ink after a predetermined period of time has elapsed since it landed on a recording medium. FIG. 2 is a schematic diagram showing a difference in glossiness between a recording location of an inkjet head on the upstream side of the transport direction and a recording location of an inkjet head on the downstream side in a conventional inkjet recording apparatus.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated example. Furthermore, in the following description, parts having the same functions and configurations will be denoted by the same reference numerals, and the description thereof will be omitted.
Furthermore, in the following description, the conveyance direction of the recording medium will be referred to as the X direction, and the width direction of the recording medium orthogonal to the X direction will be referred to as the Y direction.

[Overall configuration of first embodiment]
FIG. 1 is a sectional view showing a schematic configuration of an inkjet recording apparatus 1 according to a first embodiment of the present invention. FIG. 2 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1. As shown in FIG.
As shown in FIGS. 1 and 2, the inkjet recording apparatus 1 includes a paper feeding section 10, an image forming section 20, a paper discharging section 30, a control section 40, a storage section 50, a conveyance drive section 60, An operation display section 70 is provided. Further, the inkjet recording device 1 is connected to an external device 2.

(Inkjet recording device)
The inkjet recording apparatus 1 transports the recording medium P stored in the paper feed section 10 to the image forming section 20 under the control of the control section 40 . The inkjet recording apparatus 1 forms an image on a recording medium P using an image forming section 20. Then, the inkjet recording apparatus 1 conveys the recording medium P on which the image is formed to the paper discharge section 30 and discharges the recording medium P.

Note that in the following description, the case where the recording medium P is paper, particularly plain paper, will be exemplified, but the present invention is not limited to this. The recording medium P may be any medium that can fix ink that has landed on its surface. The recording medium P may be, for example, coated paper, cloth or sheet-like resin.

[Paper feed section]
The paper feed section 10 includes a paper feed tray 11 that stores the recording medium P, and a medium supply section 12 that transports and supplies the recording medium P from the paper feed tray 11 to the image forming section 20.
The medium supply unit 12 includes, for example, a ring-shaped belt whose inner side is supported by two rollers. Then, the medium supply section 12 transports the recording medium P from the paper feed tray 11 to the image forming section 20 by rotating the two rollers with the recording medium P placed on the belt.

[Image forming section]
The image forming section 20 includes a transport section 21, a delivery unit 22, a paper heating section 23, a head unit 24, a fixing section 25, a delivery section 26, and the like.

{Transportation section}
The conveyance unit 21 holds the recording medium P placed on the conveyance surface 211a (placing surface) of the cylindrical conveyance drum 211. The conveyance drum 211 rotates and moves around a rotation shaft (cylindrical shaft) extending in the Y direction. The transport drum 211 transports the recording medium P placed on the transport surface 211a in the X direction.

<Transport drum>
The transport drum 211 includes a claw portion (not shown) and a suction portion (not shown) for holding the recording medium P on its transport surface 211a. The ends of the recording medium P are held down by the claws. Further, the recording medium P is held on the conveyance surface 211a by being attracted to the conveyance surface 211a by the suction section.
The conveyance unit 21 is connected to a conveyance drum motor (not shown) for rotating the conveyance drum 211. The conveyance drum 211 rotates by an angle proportional to the amount of rotation of the conveyance drum motor.

{Delivery unit}
The delivery unit 22 delivers the recording medium P transported by the medium supply section 12 of the paper feed section 10 to the transport section 21 . The delivery unit 22 is provided at a position between the medium supply section 12 and the transport section 21. Then, the delivery unit 22 holds and picks up one end of the recording medium P transported from the medium supply section 12 with the swing arm section 221, and delivers it to the transport section 21 via the delivery drum 222.

{Paper heating section}
The paper heating section 23 is provided between the placement position of the delivery drum 222 and the placement position of the head unit 24. The paper heating unit 23 heats the recording medium P transported by the transport unit 21 so that the temperature of the recording medium P falls within a predetermined temperature range.
The paper heating section 23 includes, for example, an infrared heater. The paper heating section 23 energizes the infrared heater to generate heat based on a control signal supplied from the control section 40 .

{head unit}
The head unit 24 includes a plurality of inkjet heads 241, as shown in FIG. The inkjet head 241 includes a plurality of nozzle openings 242, as shown in FIG. The head unit 24 forms an image by ejecting ink onto the recording medium P from a plurality of nozzle openings 242 at appropriate timing. The head unit 24 is arranged so that the nozzle surface and the conveyance surface 211a are separated by a predetermined distance.
Details of the inkjet head 241 will be described later.

Four head units 24 are arranged in the inkjet recording apparatus 1 according to this embodiment. The four head units 24 respectively correspond to four colors of ink: yellow (Y), magenta (M), cyan (C), and black (K).
For example, as shown in FIG. 1, the four head units 24 are arranged at predetermined intervals in the order of colors Y, M, C, and K from the upstream side in the transport direction.

Furthermore, as the ink ejected from the nozzle opening 242, ink that undergoes a sol-gel phase transition is used. Ink that undergoes a sol-gel phase transition contains a gelling agent, and changes its phase to a gel-like or sol-like state depending on the temperature. Furthermore, ink that undergoes a sol-gel phase transition has the property of curing when irradiated with energy rays such as ultraviolet rays. Further, the ink contains a pigment.

The head unit 24 includes an ink heating section (not shown). The ink heating section operates under the control of the control section 40. The ink heating section heats the ink storage section 27 (see FIG. 4) to a predetermined reference temperature at which the ink stored therein becomes a sol.
The ink heated by the ink heating section is ejected from the nozzle opening 242. The ink that has landed on the recording medium P quickly becomes gel-like due to natural cooling and solidifies on the recording medium P.

Further, the ink heating section includes a temperature measuring section. The heating operation of the ink heating section is switched by the control section 40, and the temperature of the ink is maintained so that a predetermined reference temperature is detected by the temperature measurement section. The switching of the heating operation of the ink heating unit may be a simple on/off operation or may be a step-like switching in multiple stages.
Further, the switching of the heating operation of the ink heating unit may be PWM (Pulse Width Modulation) control using on/off operation at a high frequency.

Note that although FIG. 1 illustrates a case where the inkjet recording apparatus 1 includes four head units 24, the present invention is not limited to this. The number of head units 24 arranged in one inkjet recording apparatus 1 may be three or less or five or more.
Furthermore, the configuration is not limited to arranging one head unit 24 for each color of ink, but a plurality of head units 24 may be arranged. Further, although a plurality of head units 24 are arranged in the X direction in FIG. 1, a plurality of head units 24 may be arranged in the Y direction.

<Head drive unit>
The head drive unit 24a supplies a drive signal to the image forming element of the inkjet head 241 to cause the piezoelectric element to perform a deforming operation at an appropriate timing according to image data. As a result, an amount of ink corresponding to the pixel value of the image data is ejected from the nozzle opening 242.

{Fusing part}
The fixing section 25 has a light emitting section arranged across the width of the transport section 21 in the Y direction. The light emitting section emits energy rays such as ultraviolet rays to the recording medium P placed on the transport section 21 .
The fixing unit 25 hardens and fixes the gel-like ink ejected onto the recording medium P by emitting energy rays. The light emitting section is arranged facing the conveyance surface 211a between the arrangement position of the head unit 24 and the arrangement position of the delivery drum 261, which will be described later.

{Delivery Department}
The delivery section 26 includes a cylindrical transfer drum 261 that transfers the recording medium P from the conveyance section 21 to the belt loop 262. Furthermore, the delivery section 26 has a belt loop 262 having a ring-shaped belt whose inner side is supported by two rollers.
The delivery unit 26 sends out the recording medium P transferred from the conveyance unit 21 to the delivery drum 261 to the paper discharge unit 30 through the belt loop 262.

[Paper output section]
The paper discharge section 30 has a plate-shaped paper discharge tray 31. The recording medium P sent out from the image forming section 20 by the delivery section 26 is placed on the paper discharge tray 31.

[Control unit]
The control unit 40 includes a CPU (Central Processing Unit) 41, a RAM (Random Access Memory) 42, and a ROM (Read Only Memory) 43.

{CPU}
The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and executes the programs.
Further, the CPU 41 centrally controls the overall operation of the inkjet recording apparatus 1.

{RAM}
The RAM 42 provides a working memory space for the CPU 41 and stores temporary data.
Note that the RAM 42 may include nonvolatile memory.

{ROM}
The ROM 43 stores various control programs executed by the CPU 41, setting data, and the like.
Note that in place of the ROM 43, a rewritable nonvolatile memory such as an EEPROM (Electrically Erasable and Programmable Read Only Memory) or a flash memory may be used.

{Other effects}
Furthermore, when the control unit 40 acquires a print job from the external device 2, it functions as an acquisition unit that acquires image information from image data related to the print job.
The control unit 40 also controls an adjustment unit 246, which will be described later.

{Storage section}
The storage unit 50 stores a print job (image forming command) input from the external device 2, image data related to the print job, and the like. The print job includes information specifying image data related to the image to be formed, as well as information related to the type such as the size and thickness of the recording medium P on which the image is formed.
As the storage unit 50, for example, an HDD (Hard Disk Drive) is used, and a DRAM (Dynamic Random Access Memory) or the like may also be used in combination.

{Transport drive unit}
The conveyance drive section 60 supplies a drive signal to the conveyance drum motor of the conveyance drum 211 based on the control signal supplied from the control section 40 . Then, the transport drum 211 is rotated at a predetermined speed and timing.
Further, the transport drive section 60 supplies drive signals to motors for operating the medium supply section 12, the delivery unit 22, and the delivery section 26. Then, the recording medium P is supplied to the transport section 21 and discharged from the transport section 21.

{Operation display section}
The operation display unit 70 includes a display device such as a liquid crystal display or an organic EL display. Further, the operation display unit 70 includes input devices such as operation keys and a touch panel placed over the screen of the display device.
The operation display unit 70 displays various information on a display device. Further, the operation display section 70 converts a user's input operation on the input device into an operation signal, and outputs the signal to the control section 40 .

(external device)
The external device 2 supplies a print job, image data, etc. to the control unit 40. External device 2 is, for example, a personal computer.

<Inkjet head>
FIG. 3 is a bottom view showing the configuration of one head unit 24. As shown in FIG. FIG. 3 shows a nozzle surface of the head unit 24 that faces the transport surface 211a of the transport drum 211.
The head unit 24 includes a plurality of inkjet heads 241 mounted on a carriage 243.

In this embodiment, among the plurality of inkjet heads 241, the inkjet head 241 on the downstream side (upper side in FIG. 3) is referred to as a first inkjet head 241a. Further, the inkjet head 241 on the upstream side (lower side in FIG. 3) is referred to as a second inkjet head 241b.

Each inkjet head 241 is provided with a pressure chamber that stores ink and a piezoelectric element provided on the wall of the pressure chamber. Further, the inkjet head 241 is provided with a plurality of image forming elements (recording elements) each having a nozzle opening 242.
In the image forming element, when a drive signal is input from the head drive unit 24a, the pressure chamber is deformed by deformation of the piezoelectric element, and the pressure inside the pressure chamber changes. Then, the inkjet head 241 discharges ink from the nozzle opening 242 communicating with the pressure chamber due to the change in pressure.

Further, as shown in FIG. 3, one inkjet head 241 has a plurality of nozzle rows each including a plurality of nozzle openings 242. In the nozzle row, nozzle openings 242 are arranged at equal intervals along the Y direction. Moreover, one nozzle row is provided so that the arrangement interval of the nozzle openings 242 is shifted by half in the Y direction with respect to another nozzle row adjacent in the X direction.

Further, the plurality of inkjet heads 241 in one head unit 24 are arranged in multiple rows in a houndstooth pattern. This is to ensure that the arrangement range of the nozzle openings 242 in the Y direction is seamlessly connected.

The arrangement range in the Y direction of the nozzle openings 242 included in the head unit 24 covers the width in the Y direction of the image forming area of the recording medium P transported by the transport section 21 . Further, the position of the head unit 24 is fixed with respect to the rotation axis of the transport drum 211 during image formation.
That is, the head unit 24 has a line head capable of ejecting ink over the image forming area of the recording medium P in the Y direction. Further, the inkjet recording apparatus 1 is a single-pass type inkjet recording apparatus.

<Ink supply route>
Next, the ink supply path from the head unit 24 to each inkjet head 241 will be explained.
FIG. 4 is a diagram illustrating a configuration related to one ink supply path in one head unit 24. As shown in FIG. 4, the head unit 24 includes an ink storage section 27. The ink in the main tank 271 in the ink storage section 27 is pumped out and supplied to the sub tank 272 by the operation of a supply pump (not shown) or the like. Further, the ink in the sub-tank 272 is supplied to each inkjet head 241 via the ink supply channel 244 by the operation of a supply pump or the like.

Preferably, the ink supply path has a circulating structure. That is, it is preferable that the ink not ejected by each inkjet head 241 be returned to the sub tank 272 via the ink discharge channel 245 or the like. However, the ink supply path is not limited to the circulation structure.

<Adjustment section>
The head unit 24 also includes an adjustment section 246. The adjustment unit 246 creates a temperature difference between the ink ejected from the first inkjet head 241a and the ink ejected from the second inkjet head 241b. The adjustment unit 246 is provided in at least one of the first inkjet head 241a and the second inkjet head 241b. The operation of the adjustment section 246 is based on an instruction signal from the control section 40.

The adjustment section 246 according to this embodiment includes a temperature detection section 246a and a heating section 246b. Further, the adjustment section 246 is provided in the first inkjet head 241a.

≪Temperature detection part≫
The temperature detection unit 246a detects the temperature of the object to which it is attached. In this embodiment, the temperature detection unit 246a detects the temperature of the first inkjet head 241a.

≪Heating part≫
The heating unit 246b heats the attached object using a heating signal received from the control unit 40 according to the temperature detection result of the temperature detection unit 246a.
The heating unit 246b is, for example, a heat transfer member attached to the outer wall surface of the first inkjet head 241a. More specifically, the heating section 246b is a heater using a heating wire that generates Joule heat when energized. Furthermore, the heating section 246b may include a heat conductive plate that transmits heat from the heater.

[Temperature control of the first embodiment]
The control of the adjustment unit 246 according to the first embodiment by the control unit 40 will be explained based on the flowchart of FIG. 5.

First, the control unit 40 acquires a print job from, for example, the external device 2 (S101). The control unit 40 acquires image data from the print job (S102). Then, the control unit 40 determines whether the image data includes a specific image such as a photograph or an illustration (step S103).

If the image data does not include a specific image (step S103; No), the control unit 40 executes the print job without controlling the ink temperature (step S109). Then, the image recording operation ends.

Images such as photographs and illustrations tend to stand out if they have uneven gloss. Therefore, when printing these specific images, it is necessary to control the temperature of the ink. On the other hand, if a specific image is not included, it is preferable not to control the ink temperature.
This is because if a specific image is not included, even if the glossiness is uneven, it is less noticeable. Further, controlling the temperature of the ink by the adjustment unit 246 takes a predetermined amount of time due to the heating process, and productivity can be improved if the temperature is not controlled.
In particular, when the image data is only text characters, for example, the text characters are long and thin lines, and even if there is unevenness in glossiness, it is very difficult to notice, so it is preferable not to control the ink temperature.

If the image data includes a specific image (step S103; Yes), the control unit 40 controls the adjustment unit 246 to control the temperature of the ejected ink. The control unit 40 acquires the temperature of the first inkjet head 241a using the temperature detection unit 246a of the adjustment unit 246 (Step S104). Then, the control unit 40 determines whether the temperature of the first inkjet head 241a is a predetermined temperature higher than the reference temperature (step S105).
Note that in this embodiment, for example, when the reference temperature is 80°C, the predetermined temperature is 85°C.

If the temperature of the first inkjet head 241a is not at the predetermined temperature (step S105; No), the control unit 40 determines whether the temperature of the first inkjet head 241a is lower than the predetermined temperature (step S106). If the temperature is lower than the predetermined temperature (Step S106; Yes), the control unit 40 heats the first inkjet head 241a using the heating unit 246b (Step S107). After heating for a predetermined time, the process moves to step S104, and the control unit 40 again acquires the temperature of the first inkjet head 241a using the temperature detection unit 246a.

If the temperature is not lower than the predetermined temperature, that is, higher than the predetermined temperature (step S106; No), the control unit 40 waits for a predetermined time until the temperature of the first inkjet head 241a falls to the predetermined temperature ( Step S108). After a predetermined period of time, the process moves to step S104, and the control unit 40 acquires the temperature of the first inkjet head 241a again using the temperature detection unit 246a.

If the first inkjet head 241a is at a predetermined temperature (step S105; Yes), the control unit 40 executes the print job (step S109). After executing the print job, the image recording operation ends.

[Technical effect]
As described above, the control unit 40 uses the adjustment unit 246 to create a temperature difference in the ink between the first inkjet head 241a and the second inkjet head 241b. Specifically, by heating the first inkjet head 241a by the heating unit 246b, the ejected ink is made to have a higher temperature than the reference temperature.

The distance from the recording location of the first inkjet head 241a to the fixing section 25 is shorter than the distance from the recording location of the second inkjet head 241b to the fixing section 25. However, in the present invention, the temperature of the ink ejected from the first inkjet head 241a can be higher than the temperature of the ink ejected from the second inkjet head 241b because the distance to the fixing section 25 is short. This promotes wetting and spreading of the ink ejected from the first inkjet head 241a. Therefore, the image quality and glossiness can be made to be approximately the same between the recording area of the first inkjet head 241a and the recording area of the second inkjet head 241b.
As a result, the formed image is less likely to have unevenness in image quality or gloss.

Further, the control unit 40 determines whether to control the adjustment unit 246 according to the information of the image acquired by the acquisition unit.
According to this configuration, since the ink temperature is controlled only when the recording operation requires temperature adjustment, productivity can be improved.

Specifically, when the control unit 40 determines that the image information includes a photograph, the control unit 40 controls the adjustment unit 246.
According to this configuration, it becomes possible to draw high-quality photographs in which unevenness in image quality and gloss is particularly noticeable.

[Overall configuration of second embodiment]
Next, an inkjet recording apparatus 1 according to a second embodiment will be described.
Note that the same parts as in the first embodiment are given the same reference numerals and the description thereof will be omitted.
In the inkjet recording apparatus 1 according to the second embodiment, an adjustment section 246 is provided in the ink supply channel 244.

Specifically, the adjustment unit 246 is provided in the ink supply channel 244, which communicates with the first inkjet head 241a and supplies ink, among the ink supply channels 244.
Then, the temperature detection unit 246a detects the temperature of the ink supply channel 244. Further, the heating unit 246b heats the ink supply channel 244.

[Temperature control of second embodiment]
The control of the adjustment unit 246 according to the second embodiment by the control unit 40 will be explained based on the flowchart of FIG. 6.
Note that detailed explanation of steps S201 to S203, which overlap with steps S101 to S103 according to the first embodiment, will be omitted.

If the image data includes a specific image (step S203; Yes), the control unit 40 controls the ink temperature by controlling the adjustment unit 246. The control unit 40 uses the temperature detection unit 246a of the adjustment unit 246 to acquire the temperature of the ink supply channel 244 communicating with the first inkjet head 241a (Step S204). Then, the control unit 40 determines whether the temperature is a predetermined temperature higher than the reference temperature (step S205).

If the temperature of the ink supply channel 244 is not the predetermined temperature (step S205; No), the control unit 40 determines whether the temperature of the ink supply channel 244 is lower than the predetermined temperature (step S206). If the temperature is lower than the predetermined temperature (Step S206; Yes), the control unit 40 heats the ink supply channel 244 using the heating unit 246b (Step S207). After heating for a predetermined time, the process moves to step S204, and the control unit 40 acquires the temperature of the ink supply channel 244 again using the temperature detection unit 246a.

If the temperature is not lower than the predetermined temperature, that is, higher than the predetermined temperature (step S206; No), the control unit 40 waits for a predetermined time until the temperature of the ink supply channel 244 falls to the predetermined temperature (step S208). . After a predetermined period of time, the process moves to step S204, and the control unit 40 acquires the temperature of the ink supply channel 244 again using the temperature detection unit 246a.

If the ink supply channel 244 is at a predetermined temperature (step S205; Yes), the control unit 40 executes the print job (step S209). After executing the print job, the image recording operation ends.

[Technical effect]
As described above, in the second embodiment, the ink supply channel 244 communicating with the first inkjet head 241a is heated so that the ink to be ejected has a higher temperature than the reference temperature.
With this configuration as well, it is possible to make the image quality and glossiness of the recording area of the first inkjet head 241a and the recording area of the second inkjet head 241b substantially the same. In addition, unevenness in image quality and gloss of the formed image can be made less likely to occur.

[Modified example]
Note that, in the above, when the image data includes only text characters, it is preferable not to control the ink temperature, but the present invention is not limited to this. For example, if the text is a text character with a design such as a logo, or if the stroke of the character is thicker than in a normal format, unevenness in image quality or gloss may be noticeable.

Therefore, if the control unit determines in step S103 or S203 that a specific image is not included, a configuration may be adopted in which the user is asked to determine whether or not to control the ink temperature. In this configuration, for example, the operation display unit 70 receives user instructions. Further, at this time, the image data may be displayed on the operation display section 70.

Further, in steps S103 and S203, the control unit 40 determines whether or not to control the ink temperature depending on whether a specific image is included, but the present invention is not limited to this.
For example, the configuration may be such that the acquisition unit acquires the concealment rate of the image, and the control unit 40 determines whether the concealment rate is equal to or higher than a predetermined value.

Further, in the first and second embodiments, the adjustment unit 246 is attached to either the inkjet head 241 or the ink supply channel 244, but the present invention is not limited to this.
That is, a configuration may be adopted in which the adjustment section 246 is attached to both the inkjet head 241 and the ink supply channel 244, and the control section 40 controls both adjustment sections 246.

Further, although FIG. 3 shows an example in which the head unit 24 includes two rows of inkjet heads 241, one upstream and one downstream, the present invention is not limited to this.
That is, the head unit 24 may include three or more rows of inkjet heads 241.

In this configuration, the most upstream inkjet head 241 is the second inkjet head 241b. Further, the most downstream inkjet head 241 is the first inkjet head 241a. On the other hand, the other inkjet heads 241 are the first inkjet head 241a and the second inkjet head 241b.
Therefore, it is preferable that the adjustment unit 246 be attached to the inkjet heads 241 except for the second inkjet head 241b located at the most upstream side. Further, it is more preferable to have the control unit 40 control each adjustment unit 246 so that the temperature of the ejected ink gradually increases from the second inkjet head 241b at the most upstream side toward the downstream side.

Further, in the above description, the first inkjet head 241a and the second inkjet head 241b are provided in one head unit 24, but the present invention is not limited to this.
That is, among the plurality of head units 24, the downstream side may include the first inkjet head 241a, and the upstream side may include the second inkjet head 241b.

Further, in the above description, the adjusting section 246 includes the heating section 246b and is attached to the first inkjet head 241a or the ink supply channel 244 communicating with the first inkjet head 241a, but the present invention is not limited to this.
That is, the adjustment section 246 may be a cooling section such as a fan, instead of the heating section 246b. In this configuration, the adjustment section 246 is attached to the second inkjet head 241b or the ink supply channel 244 that communicates with the second inkjet head 241b. Then, the control unit 40 controls the adjustment unit 246 so that the temperature of the ink ejected from the second inkjet head 241b becomes a predetermined temperature lower than the reference temperature.

Further, in step S108 and step S208, when the temperature of the first inkjet head 241a or the ink supply flow path 244 is higher than a predetermined temperature, it is assumed that the process waits until the temperature reaches a predetermined temperature, but the present invention is not limited to this.
That is, the adjustment unit 246 may include not only the heating unit 246b but also a cooling unit, and may cool the first inkjet head 241a or the ink supply channel 244 until it reaches a predetermined temperature in step S108 and step S208. By doing so, productivity can be further improved.

[Other configurations]
Note that the present invention is not limited to the above-described embodiment and each modification, and various changes are possible.

For example, in the above description, the inkjet recording apparatus 1 in which the recording medium P is conveyed by the conveyance drum 211 as the conveyance unit 21 is illustrated, but the present invention is not limited to this. For example, the recording medium P may be transported by a transport belt that is supported by two or more rollers and moves according to the rotation of the rollers.

Further, in the above description, the inkjet recording apparatus 1 that ejects ink that becomes a sol by being heated to a reference temperature by the ink heating section has been illustrated, but the present invention is not limited to this.
For example, various known inks including inks that are in a sol or liquid state at room temperature may be ejected.

Furthermore, in the above description, an HDD, a semiconductor non-volatile memory, etc. are exemplified as a computer-readable medium for the program according to the present invention, but the medium is not limited thereto.
As other computer-readable media, it is possible to apply a portable recording medium such as a CD (Compact Disk)-ROM. Further, a carrier wave is also applied as a medium for providing data of the program according to the present invention via a communication line.

Further, an image reading section for reading an image formed on the recording medium P may be provided further downstream of the fixing section 25. Then, the image reading section may acquire the glossiness and image quality of each part of the recording medium P, and the obtained information may be sequentially reflected in the control content of the adjustment section 246 by the control section 40.

The embodiments of the present invention and their modifications have been described above, but the descriptions in the embodiments and modifications described above are only preferred examples of the present invention, and the present invention is not limited thereto.

1 Inkjet recording device 21 Transport section 24 Head unit 241 Inkjet head 241a First inkjet head 241b Second inkjet head 242 Nozzle opening 244 Ink supply channel 246 Adjustment section 27 Ink storage section 40 Control section (acquisition section)
P Recording medium

Claims (9)

an inkjet head that records an image by ejecting ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium;
an adjustment unit that adjusts the temperature of the ink discharged from the nozzle opening;
A control unit that controls the adjustment unit,
A plurality of the inkjet heads are arranged along the conveyance direction of the recording medium,
The control unit is configured such that the temperature of the ink ejected from a first inkjet head among the plurality of inkjet heads is such that the ink is ejected from a second inkjet head disposed upstream of the first inkjet head in the transport direction. An inkjet recording apparatus that controls the adjustment section so that the temperature is higher than the temperature of the ink. The inkjet recording apparatus according to claim 1, wherein the ink ejected from each inkjet head is of the same color. The inkjet recording apparatus according to claim 1 or 2, wherein the control section controls the adjustment section so that the temperature of the first inkjet head is higher than the temperature of the second inkjet head. an ink storage section in which the ink is stored;
a plurality of ink supply channels that respectively supply the ink stored in the ink storage section to a plurality of inkjet heads;
The control unit controls the adjustment unit so that the temperature of the ink supply channel communicating with the first inkjet head is higher than the temperature of the ink supply channel communicating with the second inkjet head. The inkjet recording apparatus according to claim 1 or 2, wherein the inkjet recording apparatus is controlled. Equipped with an acquisition unit that acquires image information,
The inkjet recording apparatus according to claim 1 or 2, wherein the control section determines whether to control the adjustment section according to information on the image acquired by the acquisition section. 6. The inkjet recording apparatus according to claim 5, wherein the control section controls the adjustment section if it is determined from the image information acquired by the acquisition section that the image includes a photograph. Equipped with a head unit,
The inkjet recording apparatus according to claim 1, wherein the head unit includes the first inkjet head and the second inkjet head. an inkjet head that records an image by ejecting ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium;
an adjustment unit that adjusts the temperature of the ink discharged from the nozzle opening;
A control unit that controls the adjustment unit,
An ink temperature control method in an inkjet recording apparatus in which a plurality of the inkjet heads are arranged along the conveyance direction of a recording medium,
The temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is the same as that of the ink ejected from the second inkjet head disposed upstream of the first inkjet head in the transport direction. An ink temperature control method that controls the adjustment section so that the temperature is higher than the temperature of the ink. an inkjet head that records an image by ejecting ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium;
an adjustment unit that adjusts the temperature of the ink discharged from the nozzle opening,
A program that causes a computer installed in an inkjet recording apparatus in which a plurality of inkjet heads are arranged along the conveyance direction of a recording medium to function as a control unit that controls the adjustment unit,
The control unit is configured to control the temperature of the ink ejected from a first inkjet head among the plurality of inkjet heads, such that the ink ejected from a second inkjet head disposed upstream of the first inkjet head in the transport direction. A program that controls the adjustment unit so that the temperature is higher than the temperature of the ink.

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