Inkjet recording device, ink temperature control method, and program

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

Technical Field

[0001] The present invention relates to an inkjet recording apparatus, an ink temperature control method, and a program.

Background Art

[0002] Conventionally, an inkjet recording apparatus including a plurality of head units has been known. Each head unit includes a plurality of inkjet heads. The inkjet recording apparatus ejects inks of respective colors from each head unit and lands the inks at desired positions on a recording medium conveyed in a predetermined conveyance direction.

[0003] Such an inkjet recording apparatus emits energy rays such as ultraviolet rays on the downstream side in the conveyance direction from the ink ejection position of the head unit. The ink irradiated with the energy rays is cured. Thereby, the ink is fixed on the recording medium.

[0004] On the other hand, the ink is not cured until it is irradiated with the energy rays. Therefore, as shown in FIGS. 7A and 7B, as time elapses from landing, the ink spreads and becomes flat on the recording medium. When the ink becomes flat, the glossiness increases. Further, the upstream head unit provided on the upstream side in the conveyance direction is more separated from the energy ray emission device than the downstream head unit provided on the downstream side in the conveyance direction. Therefore, it takes more time for the energy rays to be irradiated on the upstream head unit from the landing of the ink than on the downstream head unit.

[0005] Therefore, the spreading of the ink progresses more until the energy rays are irradiated on the portion recorded by the upstream head unit than on the portion recorded by the downstream head unit. Then, the portion recorded by the upstream head unit has a higher glossiness than the portion recorded by the downstream head unit. As a result, there has been a problem that unevenness occurs in the image quality and gloss of the image.

[0006] Therefore, in an inkjet recording device using multiple colors of ink, an invention has been developed in which the phase transition temperature of the ink of the color ejected from the upstream head unit is set to be higher (see, for example, Patent Document 1). This results in a substantially uniform wetting spread of each color of ink. Thus, it is possible to prevent inconsistencies in image quality and gloss between head units. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2012-121288 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] However, as shown in Figure 8, within a head unit of the same color, ink wetting spreads more rapidly in the recording area of ​​the upstream inkjet head than in the recording area of ​​the downstream inkjet head. This results in unevenness in the image quality and gloss of the image formed on the recording medium. This problem cannot be solved by the invention described in Patent Document 1.

[0009] To solve these problems, the present invention aims to provide an inkjet recording apparatus, an ink temperature control method, and a program that are less prone to unevenness in the image quality and gloss of the formed image. [Means for solving the problem]

[0010] The invention described in claim 1 is an inkjet recording apparatus, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The system comprises a control unit for controlling the adjustment unit, Multiple inkjet heads are arranged along the transport direction of the recording medium,The ink ejected from each inkjet head is the same color. The control unit controls the adjustment unit such that the temperature of the ink ejected from the first inkjet head is higher than the temperature of the ink ejected from a second inkjet head disposed upstream of the first inkjet head in the conveyance direction among the plurality of inkjet heads.

[0011] The invention according to claim 2 is ,stomach an inkjet recording apparatus, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, A control unit that controls the adjustment unit, It comprises an acquisition unit that acquires image information, Multiple inkjet heads are arranged along the transport direction of the recording medium, The control unit determines, in accordance with the image information acquired by the acquisition unit, whether or not to control the adjustment unit so that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction. The invention described in claim 3 is an inkjet recording apparatus according to claim 2, If the control unit determines from the image information acquired by the acquisition unit that the image contains a photograph, it controls the adjustment unit. The invention described in claim 4 is an inkjet recording apparatus, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, A control unit that controls the adjustment unit, An acquisition unit that acquires image information, The system includes an operation display unit that displays the image acquired by the acquisition unit and accepts an operation input to determine whether or not to adjust the ink temperature by the adjustment unit, Multiple inkjet heads are arranged along the transport direction of the recording medium, The control unit controls the adjustment unit in response to the operation input received by the operation display unit, such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

[0012] The invention according to claim 5 is an inkjet recording apparatus according to claim 1 to any one of the four items wherein the control unit controls the adjustment unit such that the temperature of the first inkjet head is higher than the temperature of the second inkjet head.

[0013] 6 The invention according to claim to any one of the four items is an inkjet recording apparatus according to claim 1 wherein there is an ink storage unit for storing the ink, The system comprises a plurality of ink supply channels that supply the ink stored in the ink storage section to a plurality of inkjet heads, respectively. 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.

[0016] The invention described in claim 7 is the same as claim 1 to any one of the four items The inkjet recording device described above, Equipped with a head unit, The head unit comprises the first inkjet head and the second inkjet head.

[0017] The invention described in claim 8 is, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The system comprises a control unit for controlling the adjustment unit, Multiple inkjet heads are arranged along the transport direction of the recording medium. The ink ejected from each inkjet head is the same color. A method for controlling ink temperature in an inkjet recording device, The adjustment unit is controlled so that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction. The invention described in claim 9 is, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The system comprises a control unit for controlling the adjustment unit, An ink temperature control method in an inkjet recording apparatus in which a plurality of inkjet heads are arranged along the transport direction of a recording medium, Based on the acquired image information, the system determines whether or not to control the adjustment unit so that the temperature of the ink ejected from the first inkjet head among the multiple inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction. The invention described in claim 10 is, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, A control unit that controls the adjustment unit, An acquisition unit that acquires image information, The system includes an operation display unit that displays the image acquired by the acquisition unit and accepts an operation input to determine whether or not to adjust the ink temperature by the adjustment unit, An ink temperature control method in an inkjet recording apparatus in which a plurality of inkjet heads are arranged along the transport direction of a recording medium, In response to the operation input received by the operation display unit, the adjustment unit is controlled so that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

[0018] Claim 11 The invention described is a program, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, It includes an adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, Multiple inkjet heads are arranged along the transport direction of the recording medium. The ink ejected from each inkjet head is the same color. The computer installed in the inkjet recording device is made to function as a control unit that controls the adjustment unit. The control unit is instructed to control the adjustment unit so that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction. The invention described in claim 12 is a program, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, It includes an adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The aforementioned inkjet heads cause a computer provided in an inkjet recording device, in which multiple heads are arranged along the transport direction of the recording medium, to function as an acquisition unit for acquiring image information and a control unit for controlling the adjustment unit. The control unit is instructed to determine whether or not to control the adjustment unit so that, according to the image information acquired by the acquisition unit, the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction. The invention described in claim 13 is a program, An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The system includes an operation display unit that displays the acquired image and accepts an operation input to determine whether or not to adjust the ink temperature using the adjustment unit, The aforementioned inkjet heads cause a computer provided in an inkjet recording device, which has multiple heads arranged along the transport direction of the recording medium, to function as an acquisition unit for acquiring image information and a control unit for controlling the adjustment unit. The control unit is instructed to control the adjustment unit in response to the operation input received by the operation display unit, such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction. [Effects of the Invention]

[0019] 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 prone to unevenness in the image quality and gloss of the formed image. [Brief explanation of the drawing]

[0020] [Figure 1] This is a schematic cross-sectional view of an inkjet recording device. [Figure 2] This is a block diagram of an inkjet recording device. [Figure 3] This is a bottom view showing the configuration of the head unit. [Figure 4] This is a schematic diagram illustrating the configuration of the ink supply path between the ink storage unit and the inkjet head. [Figure 5] This is a flowchart showing the temperature control of the ink in an inkjet recording apparatus according to the first embodiment. [Figure 6] This is a flowchart showing the temperature control of the ink in an inkjet recording device according to the second embodiment. [Figure 7A] This is a magnified side view of the ink immediately after it hit the recording medium. [Figure 7B] This is a magnified side view of ink that has landed on a recording medium and a predetermined amount of time has elapsed. [Figure 8] This is a schematic diagram showing the difference in glossiness between the recording area of ​​the inkjet head upstream and the recording area of ​​the inkjet head downstream in the transport direction of a conventional inkjet recording device. [Modes for carrying out the invention]

[0021] Preferred embodiments of the present invention will be described below with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples. In the following description, components having the same function and configuration will be denoted by the same reference numerals, and their descriptions will be omitted. Furthermore, in the following explanation, the transport direction of the recording medium will be defined as the X direction, and the width direction of the recording medium, which is perpendicular to the X direction, will be defined as the Y direction.

[0022] [Overall configuration of the first embodiment] Figure 1 is a cross-sectional view showing the schematic configuration of an inkjet recording apparatus 1 according to the first embodiment of the present invention. Figure 2 is a block diagram showing the main functional configuration of the inkjet recording apparatus 1. As shown in Figures 1 and 2, the inkjet recording device 1 comprises a paper feeding unit 10, an image forming unit 20, a paper discharge unit 30, a control unit 40, a storage unit 50, a transport drive unit 60, and an operation display unit 70. The inkjet recording device 1 is also connected to an external device 2.

[0023] (Inkjet recording device) The inkjet recording device 1, under the control of the control unit 40, transports the recording medium P stored in the paper feeding unit 10 to the image forming unit 20. The inkjet recording device 1 forms an image on the recording medium P in the image forming unit 20. Then, the inkjet recording device 1 transports the recording medium P with the image formed on it to the paper discharge unit 30 and discharges it.

[0024] In the following explanation, the recording medium P is given as an example when it is paper, particularly plain paper, but it is not limited to this. The recording medium P can be any medium capable of fixing ink that has landed on its surface. The recording medium P may be coated paper, cloth, or a sheet of resin, for example.

[0025] [Paper feed section] The paper feeding unit 10 includes a paper feeding tray 11 for storing the recording medium P, and a media supply unit 12 for transporting and supplying the recording medium P from the paper feeding tray 11 to the image forming unit 20. The media supply unit 12 includes, for example, a ring-shaped belt supported on its inner side by two rollers. The media supply unit 12 then transports the recording medium P from the paper feed tray 11 to the image forming unit 20 by rotating the two rollers while the recording medium P is placed on the belt.

[0026] [Image forming unit] The image forming unit 20 includes a transport unit 21, a transfer unit 22, a paper heating unit 23, a head unit 24, a fixing unit 25, a delivery unit 26, and the like.

[0027] {Conveyor section} The transport unit 21 holds the recording medium P placed on the transport surface 211a (placement surface) of the cylindrical transport drum 211. The transport drum 211 rotates around a rotation axis (cylindrical axis) extending in the Y direction and moves in a circular motion. The transport drum 211 then transports the recording medium P placed on the transport surface 211a in the X direction.

[0028] <Conveyor Drum> The transport drum 211 includes claws and an air intake (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. The recording medium P is also held on the transport surface 211a by being attracted to it by the air intake. The conveying unit 21 is connected to a conveying drum motor (not shown) for rotating the conveying drum 211. The conveying drum 211 rotates by an angle proportional to the amount of rotation of the conveying drum motor.

[0029] {Transfer Unit} The transfer unit 22 transfers the recording medium P, which has been transported by the media supply unit 12 of the paper feeding unit 10, to the transport unit 21. The transfer unit 22 is located between the media supply unit 12 and the transport unit 21. The transfer unit 22 then holds one end of the recording medium P transported from the media supply unit 12 with its swing arm unit 221, picks it up, and transfers it to the transport unit 21 via the transfer drum 222.

[0030] {Paper heating section} The paper heating unit 23 is located between the position of the transfer drum 222 and the position of the head unit 24. The paper heating unit 23 heats the recording medium P, which is transported by the transport unit 21, so that it reaches a temperature within a predetermined temperature range. The paper heating unit 23 has, for example, an infrared heater. The paper heating unit 23 energizes the infrared heater to generate heat based on a control signal supplied from the control unit 40.

[0031] {Head Unit} As shown in Figure 3, the head unit 24 includes a plurality of inkjet heads 241. As shown in Figure 3, the inkjet heads 241 include a plurality of nozzle openings 242. The head unit 24 ejects ink from the plurality of nozzle openings 242 onto the recording medium P at an appropriate timing to form an image. The head unit 24 is positioned such that the nozzle surface and the transport surface 211a are separated by a predetermined distance. Details about the inkjet head 241 will be described later.

[0032] The inkjet recording device 1 according to this embodiment has four head units 24 arranged in a row. Each of the four head units 24 corresponds to one of four ink colors: yellow (Y), magenta (M), cyan (C), and black (K). For example, as shown in Figure 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.

[0033] Furthermore, the ink discharged from the nozzle opening 242 is a sol-gel phase-transition ink. The sol-gel phase-transition ink contains a gelling agent and changes phase between gel and sol depending on the temperature. The sol-gel phase-transition ink also has the property of hardening when irradiated with energy rays such as ultraviolet light. In addition, the ink contains a pigment.

[0034] The head unit 24 includes an ink heating unit (not shown). The ink heating unit operates under the control of the control unit 40. The ink heating unit heats the ink storage unit 27 (see Figure 4) to a predetermined reference temperature at which the ink stored inside becomes sol. The ink, heated by the ink heating unit, is ejected from the nozzle opening 242. The ink that lands on the recording medium P quickly turns into a gel upon natural cooling and solidifies on the recording medium P.

[0035] Furthermore, the ink heating unit is equipped with a temperature measuring unit. The heating operation of the ink heating unit is switched by the control unit 40, and the ink temperature is maintained so that a predetermined reference temperature is detected by the temperature measuring unit. The switching of the heating operation of the ink heating unit may be a simple on / off operation or a step-like multi-stage switching. Furthermore, the switching of the heating operation of the ink heating unit may be controlled by PWM (Pulse Width Modulation) using high-frequency on / off operation.

[0036] Although Figure 1 illustrates a case where the inkjet recording device 1 has four head units 24, it is not limited to this. The number of head units 24 arranged in a single inkjet recording device 1 may be three or fewer, or five or more. Furthermore, the configuration is not limited to arranging one head unit 24 per ink color; multiple head units 24 may be arranged. Also, although multiple head units 24 are arranged in the X direction in Figure 1, multiple head units 24 may be arranged in the Y direction.

[0037] <Head drive unit> The head drive unit 24a supplies a drive signal to the image forming element of the inkjet head 241, causing the piezoelectric element to deform at an appropriate timing according to the image data. This causes an amount of ink corresponding to the pixel value of the image data to be ejected from the nozzle opening 242.

[0038] {Fixing part} The fixing unit 25 has a light-emitting unit that is arranged across the width of the transport unit 21 in the Y direction. The light-emitting unit emits energy rays such as ultraviolet light to the recording medium P placed on the transport unit 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 unit is positioned facing the transport surface 211a between the position of the head unit 24 and the position of the transfer drum 261, which will be described later.

[0039] {Delivery Department} The delivery unit 26 has a cylindrical transfer drum 261 that transfers the recording medium P from the transport unit 21 to the belt loop 262. The delivery unit 26 also has a belt loop 262 which has a ring-shaped belt supported on the inside by two rollers. The delivery unit 26 sends the recording medium P, which has been transferred from the transport unit 21 to the transfer drum 261, to the paper output unit 30 via the belt loop 262.

[0040] [Paper output section] The paper output unit 30 has a plate-shaped paper output tray 31. The recording medium P, which is sent out from the image forming unit 20 by the delivery unit 26, is placed on the paper output tray 31.

[0041] [Control Unit] The control unit 40 includes a CPU (Central Processing Unit) 41, RAM (Random Access Memory) 42, and ROM (Read Only Memory) 43.

[0042] {CPU} The CPU 41 reads various control programs and setting data stored in the ROM 43, stores them in the RAM 42, and then executes the program. Furthermore, the CPU 41 provides overall control over the operation of the inkjet recording device 1.

[0043] {RAM} RAM42 provides CPU41 with a working memory space and stores temporary data. Furthermore, RAM42 may include non-volatile memory.

[0044] {ROM} ROM43 stores various control programs and setting data executed by the CPU41. Alternatively, rewritable non-volatile memory such as EEPROM (Electrically Erasable and Programmable Read Only Memory) or flash memory may be used instead of ROM43.

[0045] {Other effects} Furthermore, when the control unit 40 acquires a print job from the external device 2, it acts as an acquisition unit that acquires image information from the image data related to the print job. Furthermore, the control unit 40 controls the adjustment unit 246, which will be described later.

[0046] {Storage section} The storage unit 50 stores print jobs (image formation commands) input from the external device 2, as well as image data related to those print jobs. The print job includes information specifying the image data to be formed, as well as information relating to the type of recording medium P on which the image is formed, such as its size and thickness. For the memory unit 50, for example, an HDD (Hard Disk Drive) may be used, and DRAM (Dynamic Random Access Memory) may also be used in combination.

[0047] {Transport drive unit} The transport drive unit 60 supplies a drive signal to the transport drum motor of the transport drum 211 based on a control signal supplied from the control unit 40. It then rotates the transport drum 211 at a predetermined speed and timing. Furthermore, the transport drive unit 60 supplies drive signals to the motors that operate the media supply unit 12, the transfer unit 22, and the delivery unit 26. It then causes the recording medium P to be supplied to the transport unit 21 and discharged from the transport unit 21.

[0048] {Operation display section} The operation display unit 70 is equipped with a display device such as a liquid crystal display or an organic EL display. The operation display unit 70 is also equipped with input devices such as operation keys and a touch panel superimposed on the screen of the display device. The operation display unit 70 displays various information on the display device. The operation display unit 70 also converts user input operations to the input device into operation signals and outputs them to the control unit 40.

[0049] (external device) External device 2 supplies print jobs and image data, etc., to the control unit 40. External device 2 is, for example, a personal computer.

[0050] <Inkjet head> Figure 3 is a bottom view showing the configuration of one head unit 24. Figure 3 shows the nozzle surface of the head unit 24 that faces the transport surface 211a of the transport drum 211. The head unit 24 includes multiple inkjet heads 241 mounted on a carriage 243.

[0051] In this embodiment, among the multiple inkjet heads 241, the downstream inkjet head 241 (upper part of Figure 3) is referred to as the first inkjet head 241a. The upstream inkjet head 241 (lower part of Figure 3) is referred to as the second inkjet head 241b.

[0052] Each inkjet head 241 is provided with a pressure chamber for storing ink and a piezoelectric element located on the wall of the pressure chamber. The inkjet head 241 is also provided with a plurality of image forming elements (recording elements), each having a nozzle opening 242. When a drive signal is input to the image forming element from the head drive unit 24a, the pressure chamber deforms due to the deformation of the piezoelectric element, causing a change in the pressure inside the pressure chamber. Then, the inkjet head 241 ejects ink from the nozzle opening 242 that communicates with the pressure chamber in response to this change in pressure.

[0053] Furthermore, as shown in Figure 3, a single inkjet head 241 has multiple nozzle rows, each having multiple nozzle openings 242. The nozzle openings 242 in each nozzle row are arranged at equal intervals along the Y direction. In addition, one nozzle row is positioned such that the spacing of the nozzle openings 242 in the Y direction is shifted by half in the Y direction relative to other nozzle rows adjacent in the X direction.

[0054] Furthermore, the multiple inkjet heads 241 in a single head unit 24 are arranged in multiple rows in a staggered pattern. This is to ensure that the arrangement range of the nozzle openings 242 in the Y direction is seamlessly connected.

[0055] The Y-axis arrangement range of the nozzle openings 242 included in the head unit 24 covers the Y-axis width of the image forming area of ​​the recording medium P transported by the transport unit 21. Furthermore, the position of the head unit 24 is fixed relative to the rotation axis of the transport drum 211 during image formation. In other words, the head unit 24 has a line head capable of ejecting ink across the image-forming region of the recording medium P in the Y direction. Furthermore, the inkjet recording device 1 is a single-pass inkjet recording device.

[0056] <Ink supply path> Next, we will describe the ink supply path from the head unit 24 to each inkjet head 241. Figure 4 illustrates the configuration of one ink supply path in one head unit 24. As shown in Figure 4, the head unit 24 includes an ink storage section 27. The ink in the main tank 271 of the ink storage section 27 is pumped out by the operation of a supply pump (not shown) and supplied to a sub-tank 272. The ink in the sub-tank 272 is supplied to each inkjet head 241 via an ink supply channel 244 by the operation of a supply pump or the like.

[0057] The ink supply path is preferably a circulating structure. That is, it is preferable that ink not ejected by each inkjet head 241 is returned to the sub-tank 272 via the ink discharge channel 245, etc. However, the ink supply path is not limited to a circulating structure.

[0058] <Adjustment section> Furthermore, the head unit 24 includes an adjustment unit 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 on at least one of the first inkjet head 241a and the second inkjet head 241b. The operation of the adjustment unit 246 is based on instruction signals from the control unit 40.

[0059] The adjustment unit 246 according to this embodiment includes a temperature sensing unit 246a and a heating unit 246b. The adjustment unit 246 is also provided on the first inkjet head 241a.

[0060] ≪Temperature detection unit≫ 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.

[0061] ≪Heating section≫ The heating unit 246b heats the object to which it is attached based on a heating signal received from the control unit 40 in accordance with the temperature detection result of the temperature detection unit 246a. The heating element 246b is, for example, a heat transfer member attached to the outer wall surface of the first inkjet head 241a. More specifically, the heating element 246b is a heater using an electric heating wire that generates Joule heat when energized. Furthermore, the heating element 246b may be equipped with a heat conduction plate that transmits heat from the heater.

[0062] [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 in Figure 5.

[0063] First, the control unit 40 acquires a print job from, for example, an 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).

[0064] If the image data does not contain a specific image (step S103; No), the control unit 40 does not control the ink temperature and executes the print job (step S109). Then, it terminates the image recording operation.

[0065] Images such as photographs and illustrations are prone to showing inconsistencies in gloss. Therefore, when printing these specific images, it is necessary to control the ink temperature. On the other hand, if no such images are included, it is preferable not to control the ink temperature. This is because, if certain images are not included, any unevenness in glossiness is less noticeable. Furthermore, controlling the ink temperature by the adjustment unit 246 requires a predetermined time for heating, and not controlling it actually increases productivity. In particular, if the image data consists only of text characters, for example, since text characters are long, thin lines, unevenness in glossiness is not very noticeable, it is preferable not to control the ink temperature.

[0066] If the image data contains a specific image (step S103; Yes), the control unit 40 controls the temperature of the ejected ink by controlling the adjustment unit 246. The control unit 40 obtains the temperature of the first inkjet head 241a using the temperature detection unit 246a of the adjustment unit 246 (step S104). The control unit 40 then determines whether the temperature of the first inkjet head 241a is at a predetermined temperature that is higher than the reference temperature (step S105). In this embodiment, for example, if the reference temperature is 80°C, the predetermined temperature is 85°C.

[0067] If the first inkjet head 241a is not at a 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 it is lower than the predetermined temperature (step S106; Yes), the control unit 40 heats the first inkjet head 241a with the heating unit 246b (step S107). After heating for a predetermined time, the process proceeds to step S104, where the control unit 40 obtains the temperature of the first inkjet head 241a again using the temperature detection unit 246a.

[0068] If the temperature is not lower than the predetermined temperature, i.e., 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 drops to the predetermined temperature (step S108). After the predetermined time, the process transitions to step S104, and the control unit 40 obtains the temperature of the first inkjet head 241a again using the temperature detection unit 246a.

[0069] 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 the print job is executed, the image recording operation is terminated.

[0070] [Technical effects] 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, the heating unit 246b heats the first inkjet head 241a so that the ejected ink is at a temperature higher than the reference temperature.

[0071] The distance from the recording area of ​​the first inkjet head 241a to the fuser unit 25 is shorter than the distance from the recording area of ​​the second inkjet head 241b to the fuser unit 25. However, in this invention, because the distance to the fuser unit 25 is shorter, the temperature of the ink ejected from the first inkjet head 241a can be made higher than the temperature of the ink ejected from the second inkjet head 241b. This promotes the wetting and spreading of the ink ejected from the first inkjet head 241a. As a result, the recording area of ​​the first inkjet head 241a and the recording area of ​​the second inkjet head 241b can be made to have approximately the same image quality and glossiness. As a result, the image quality and gloss of the resulting image are less likely to be uneven.

[0072] Furthermore, the control unit 40 determines whether or not to control the adjustment unit 246 according to the information of the image acquired by the acquisition unit. This configuration allows for improved productivity because the ink temperature is controlled only when a recording operation requires temperature adjustment.

[0073] Specifically, if the control unit 40 determines that the image information includes a photograph, it controls the adjustment unit 246. This configuration makes it possible to render high-quality images, especially those where unevenness in image quality and gloss is particularly noticeable.

[0074] [Overall configuration of the second embodiment] Next, the inkjet recording apparatus 1 according to the second embodiment will be described. In addition, parts that are the same as those in the first embodiment are denoted by the same reference numerals and their descriptions are omitted. In the second embodiment, the inkjet recording apparatus 1 has an adjustment unit 246 provided in the ink supply channel 244.

[0075] In detail, the adjustment unit 246 is provided in the ink supply channel 244 that supplies ink to the first inkjet head 241a. The temperature sensing unit 246a then detects the temperature of the ink supply channel 244. The heating unit 246b then heats the ink supply channel 244.

[0076] [Temperature control in the 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 in Figure 6. Detailed explanations of steps S201 to S203, which overlap with steps S101 to S103 according to the first embodiment, will be omitted.

[0077] If the image data contains a specific image (step S203; Yes), the control unit 40 controls the ink temperature by controlling the adjustment unit 246. The control unit 40 obtains the temperature of the ink supply channel 244 communicating with the first inkjet head 241a using the temperature detection unit 246a of the adjustment unit 246 (step S204). The control unit 40 then determines whether the temperature is a predetermined temperature higher than the reference temperature (step S205).

[0078] If the temperature of the ink supply channel 244 is not at a 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 it is lower than the predetermined temperature (step S206; Yes), the control unit 40 heats the ink supply channel 244 with the heating unit 246b (step S207). After heating for a predetermined time, the process proceeds to step S204, and the control unit 40 obtains the temperature of the ink supply channel 244 again with the temperature detection unit 246a.

[0079] If the temperature is not lower than the predetermined temperature, i.e., higher than the predetermined temperature (step S206; No), the control unit 40 waits for a predetermined time until the ink supply channel 244 drops to the predetermined temperature (step S208). After the predetermined time, the process transitions to step S204, and the control unit 40 obtains the temperature of the ink supply channel 244 again using the temperature detection unit 246a.

[0080] 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 the print job is executed, the image recording operation is terminated.

[0081] [Technical effects] As described above, in the second embodiment, the ink supply channel 244 communicating with the first inkjet head 241a is heated so that the ejected ink is at a temperature higher than the reference temperature. This configuration also makes it possible to ensure that the recording areas of the first inkjet head 241a and the second inkjet head 241b have substantially the same image quality and gloss level. Furthermore, it makes it less likely for unevenness to occur in the image quality and gloss of the resulting image.

[0082] [Differentiation] Furthermore, while it was stated above that it is preferable not to control the ink temperature when the image data contains only text characters, this is not the only case. For example, if the text characters have design elements such as logos, or if the strokes of the characters are thicker than in normal formatting, unevenness in image quality and gloss may become noticeable.

[0083] Therefore, if the control unit determines in step S103 or S203 that a specific image is not included, the system may be configured to allow the user to decide whether or not to control the ink temperature. In this configuration, for example, the operation display unit 70 receives the user's instructions. At this time, the operation display unit 70 may also display image data.

[0084] Furthermore, although steps S103 and S203 indicate that the control unit 40 determines whether or not to control the ink temperature depending on whether a specific image is included, it is not limited to this. For example, the system may be configured such that the image occlusion rate is obtained by the acquisition unit, and the control unit 40 makes a decision based on whether the occlusion rate is above a predetermined value.

[0085] Furthermore, while the adjustment unit 246 is described as being attached to either the inkjet head 241 or the ink supply channel 244 in the first and second embodiments, it is not limited to this. In other words, the adjustment unit 246 may be attached to both the inkjet head 241 and the ink supply channel 244, and the control unit 40 may control both adjustment units 246.

[0086] Furthermore, while Figure 3 illustrates a case where the head unit 24 consists of two rows of inkjet heads 241, one upstream and one downstream, the invention is not limited to this configuration. In other words, it may be a head unit 24 consisting of three or more rows of inkjet heads 241.

[0087] In this configuration, the upstream inkjet head 241 is the second inkjet head 241b. The downstream inkjet head 241 is the first inkjet head 241a. On the other hand, the other inkjet heads 241 are both the first inkjet head 241a and the second inkjet head 241b. Therefore, it is preferable that adjustment units 246 be attached to the inkjet heads 241, excluding the uppermost second inkjet head 241b. Furthermore, it is even more preferable that the control unit 40 controls each adjustment unit 246 so that the temperature of the ejected ink gradually increases as you move downstream from the uppermost second inkjet head 241b.

[0088] Furthermore, although the above assumes that the first inkjet head 241a and the second inkjet head 241b are provided in a single head unit 24, this is not limited to that. In other words, among the multiple head units 24, the downstream side may be equipped with a first inkjet head 241a, and the upstream side may be equipped with a second inkjet head 241b.

[0089] Furthermore, in the above description, the adjustment unit 246 is equipped with a heating unit 246b and is attached to the first inkjet head 241a or an ink supply channel 244 communicating with the first inkjet head 241a, but the invention is not limited to this configuration. In other words, the adjustment unit 246 may be a cooling unit such as a fan, rather than a heating unit 246b. In this configuration, the adjustment unit 246 is attached to the second inkjet head 241b or an ink supply channel 244 communicating with the second inkjet head 241b. The control unit 40 then controls the adjustment unit 246 so that the temperature of the ink ejected from the second inkjet head 241b is at a predetermined temperature lower than the reference temperature.

[0090] Furthermore, in steps S108 and S208, if the temperature of the first inkjet head 241a or the ink supply channel 244 is higher than a predetermined temperature, the system is to wait until it reaches the predetermined temperature, but this is not limited to this. In other words, the adjustment unit 246 may include not only a heating unit 246b but also a cooling unit, and in steps S108 and S208, it may cool the first inkjet head 241a or the ink supply channel 244 until it reaches a predetermined temperature. Doing so can further improve productivity.

[0091] [Other configurations] It should be noted that the present invention is not limited to the embodiments and their respective modifications, and various modifications are possible.

[0092] For example, in the above example, an inkjet recording device 1 in which a transport drum 211 transports the recording medium P as the transport unit 21 was provided, but the invention is not limited to this. For example, the recording medium P may be transported by a transport belt supported by two or more rollers and moving in accordance with the rotation of the rollers.

[0093] Furthermore, while the above example illustrates an inkjet recording device 1 that ejects ink that becomes sol-like when heated to a standard temperature by an ink heating unit, the device is not limited to this. For example, various known inks, including inks that are sol-like or liquid at room temperature, may be dispensed.

[0094] Furthermore, while examples such as HDDs and semiconductor non-volatile memory were given above as computer-readable media for the program according to the present invention, the invention is not limited to these. Other computer-readable media that can be used include portable recording media such as CD-ROMs. Furthermore, carrier waves can also be used as a medium for providing program data according to the present invention via a communication line.

[0095] Furthermore, an image reading unit may be provided further downstream of the fixing unit 25 to read the image formed on the recording medium P. The image reading unit may then acquire the glossiness and image quality of each part of the recording medium P, and these may be sequentially reflected in the control content of the adjustment unit 246 by the control unit 40.

[0096] Although embodiments and modifications thereof of the present invention have been described above, the descriptions in the above embodiments and modifications are preferred examples of the present invention and are not limited thereto. [Explanation of Symbols]

[0097] 1. Inkjet recording device 21 Conveying section 24 Head Units 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 Unit (Acquisition Unit) P recording medium

Claims

1. An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The system comprises a control unit for controlling the adjustment unit, The inkjet heads are arranged in multiple locations along the transport direction of the recording medium, and the ink ejected from each inkjet head is the same color. The control unit controls the adjustment unit such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

2. 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 for adjusting the temperature of the ink discharged from the nozzle opening, A control unit that controls the adjustment unit, It comprises an acquisition unit that acquires image information, Multiple inkjet heads are arranged along the transport direction of the recording medium, An inkjet recording apparatus in which the control unit determines whether or not to control the adjustment unit so that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head which is located upstream of the first inkjet head in the transport direction, according to the image information acquired by the acquisition unit.

3. The inkjet recording apparatus according to claim 2, wherein the control unit determines from the image information acquired by the acquisition unit that the image contains a photograph, and controls the adjustment unit.

4. 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 for adjusting the temperature of the ink discharged from the nozzle opening, A control unit that controls the adjustment unit, An acquisition unit that acquires image information, The system includes an operation display unit that displays the image acquired by the acquisition unit and accepts an operation input to determine whether or not to adjust the ink temperature by the adjustment unit, Multiple inkjet heads are arranged along the transport direction of the recording medium, The control unit controls the adjustment unit in response to an operation input received by the operation display unit, such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

5. The inkjet recording apparatus according to any one of claims 1 to 4, wherein the control unit controls the adjustment unit so that the temperature of the first inkjet head is higher than the temperature of the second inkjet head.

6. The ink storage section in which the aforementioned ink is stored, The system comprises a plurality of ink supply channels that supply the ink stored in the ink storage section to a plurality of inkjet heads, respectively. The inkjet recording apparatus according to any one of claims 1 to 4, wherein 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.

7. Equipped with a head unit, The inkjet recording apparatus according to any one of claims 1 to 4, wherein the head unit comprises the first inkjet head and the second inkjet head.

8. An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, An adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The system comprises a control unit for controlling the adjustment unit, An ink temperature control method for an inkjet recording apparatus in which a plurality of inkjet heads are arranged along the transport direction of the recording medium, and the ink ejected from each inkjet head is the same color, An ink temperature control method that controls the adjustment unit so that the temperature of the ink ejected from a first inkjet head among a plurality of inkjet heads is higher than the temperature of the ink ejected from a second inkjet head located upstream of the first inkjet head in the transport direction.

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 for adjusting the temperature of the ink discharged from the nozzle opening, The system comprises a control unit for controlling the adjustment unit, An ink temperature control method in an inkjet recording apparatus in which a plurality of inkjet heads are arranged along the transport direction of a recording medium, An ink temperature control method that determines whether or not to control the adjustment unit so that, according to the information of the acquired image, the temperature of the ink ejected from the first inkjet head among a plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

10. 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 for adjusting the temperature of the ink discharged from the nozzle opening, A control unit that controls the adjustment unit, An acquisition unit that acquires image information, The system includes an operation display unit that displays the image acquired by the acquisition unit and accepts an operation input to determine whether or not to adjust the ink temperature by the adjustment unit, An ink temperature control method in an inkjet recording apparatus in which a plurality of inkjet heads are arranged along the transport direction of a recording medium, An ink temperature control method that controls the adjustment unit in response to an operation input received by the operation display unit, such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

11. An inkjet head that ejects ink that undergoes a sol-gel phase transition from a nozzle opening onto a recording medium to record an image, It includes an adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, A program that causes a computer provided in an inkjet recording device, in which a plurality of inkjet heads are arranged along the transport direction of the recording medium and the ink ejected from each inkjet head is the same color, to function as a control unit for controlling the adjustment unit, A program that causes the control unit to control the adjustment unit such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

12. 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, It includes an adjustment unit for adjusting the temperature of the ink discharged from the nozzle opening, The program causes the inkjet heads, which are arranged in a plurality along the transport direction of the recording medium, to function as an acquisition unit for acquiring image information and a control unit for controlling the adjustment unit, A program that causes the control unit to determine whether or not to control the adjustment unit so that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction, according to the image information acquired by the acquisition unit.

13. 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 for adjusting the temperature of the ink discharged from the nozzle opening, The system includes an operation display unit that displays the acquired image and accepts an operation input to determine whether or not to adjust the ink temperature using the adjustment unit, The program causes a computer provided in an inkjet recording device, in which multiple inkjet heads are arranged along the transport direction of the recording medium, to function as an acquisition unit for acquiring image information and a control unit for controlling the adjustment unit, A program that causes the control unit to control the adjustment unit in response to an operation input received by the operation display unit, such that the temperature of the ink ejected from the first inkjet head among the plurality of inkjet heads is higher than the temperature of the ink ejected from the second inkjet head, which is located upstream of the first inkjet head in the transport direction.

Images