Inkjet printing apparatus, control method and program for image forming unit

Abstract

To prevent deterioration of the irradiation area and to perform image formation processing appropriately. [Solution] The inkjet printing apparatus includes an inkjet head that ejects ink that hardens upon irradiation with an active ray onto a recording medium, an image forming unit that includes an irradiation unit that hardens the ink by irradiating it with an active ray, a flow rate measuring unit that measures the flow rate of a cooling medium that cools the irradiation unit, and a control unit that controls the image forming unit based on the measured flow rate.

Description

Technical Field

[0001] The present disclosure relates to an inkjet printing apparatus, a control method for an image forming unit, and a program.

Background Art

[0002] Inkjet printing apparatuses that form images on a recording medium by ejecting ink droplets from nozzles of an inkjet head are known.

[0003] In an inkjet printing apparatus, the inkjet head ejects ultraviolet curable ink that cures upon irradiation with ultraviolet rays onto a recording medium, and an irradiation unit fixes the ink onto the recording medium by applying ultraviolet rays to the ink on the recording medium, thereby forming an image.

[0004] In such an inkjet printing apparatus, the irradiation unit is configured to irradiate ultraviolet rays with a UVLED. If the irradiation unit is continuously driven for a long period of time, the temperature of the irradiation unit, specifically the UVLED, rises. When the temperature of the UVLED rises, the irradiation efficiency decreases, ultraviolet rays cannot be applied uniformly, and there is a risk that images cannot be formed properly. To address this, for example, Patent Document 1 responds by detecting the temperature of the irradiation unit, stopping the irradiation of the irradiation unit, and halting the image forming process.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, in Patent Document 1, the heated irradiation unit is detected, and then the irradiation of the irradiation unit, that is, the lighting of the UVLED, is stopped. This causes thermal stress to be applied to the irradiation unit, leading to progressive element degradation and a shortened service life.

[0007] Furthermore, since the system stops illuminating the irradiation area only after detecting that the area has been heated, ink that has already been ejected onto the recording medium by the inkjet head is not cured by the irradiation area, resulting in a problem where the ink remains uncured. When recording media with uncured ink attached are transported within the device, the ink adheres to the inside of the device, contaminating the device itself and subsequently contaminating other recording media to be printed on.

[0008] This disclosure has been made in view of the above-mentioned problems, and aims to provide an inkjet printing apparatus, a control method for the image forming section, and a program that can prevent deterioration of the irradiation section and suitably form images. [Means for solving the problem]

[0009] The inkjet printing apparatus according to the present invention is An image forming unit including an inkjet head that ejects ink that hardens upon irradiation with an active ray onto a recording medium, and an irradiation unit that hardens the ink by irradiating it with an active ray, A flow rate measuring unit for measuring the flow rate of the cooling medium used to cool the irradiation unit, A control unit that controls the image forming unit based on the measured flow rate, It holds.

[0010] The control method for the image forming unit according to the present invention is: In an inkjet printing apparatus having an inkjet head that ejects ink cured by irradiation with an active ray onto a recording medium, and an image forming unit that includes an irradiation unit for curing the ink by irradiating it with an active ray, The flow rate measuring unit measures the flow rate of the cooling medium that cools the irradiation unit. The image forming unit is controlled based on the measured flow rate.

[0011] The program according to the present invention is An inkjet printing apparatus has a computer comprising an inkjet head that ejects ink that hardens upon irradiation with an active ray onto a recording medium, an image forming unit that includes an irradiation unit that hardens the ink by irradiating it with an active ray, and a flow rate measuring unit that measures the flow rate of a cooling medium that cools the irradiation unit, Based on the measured flow rate, the image forming unit is controlled to perform a process. [Effects of the Invention]

[0012] According to the printing apparatus of this disclosure, deterioration of the irradiation area can be prevented and images can be formed suitably. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a diagram showing the schematic configuration of a printing apparatus according to one embodiment of the present invention. [Figure 2] Figure 2 is a schematic diagram showing the configuration of the head unit of a printing apparatus according to one embodiment of the present invention. [Figure 3] Figure 3 is a block diagram showing the main functional configuration of a printing apparatus according to one embodiment of the present invention. [Figure 4] Figure 4 is a schematic diagram showing the main components of a printing apparatus according to one embodiment of the present invention. [Figure 5] Figure 5 is a flowchart illustrating the control of a printing apparatus according to one embodiment of the present invention. [Figure 6] Figure 6 is a flowchart illustrating another control method for a printing apparatus according to one embodiment of the present invention. [Modes for carrying out the invention]

[0014] Preferred embodiments of this disclosure will be described in detail below with reference to the attached drawings. In this specification and the drawings, components having substantially the same function are denoted by the same reference numerals, and redundant descriptions will be omitted.

[0015] [Overall configuration of an inkjet printing device] Hereinafter, the configuration of an inkjet printing apparatus 1 according to an embodiment of the present invention will be described with reference to FIG. 1 to FIG. 3.

[0016] FIG. 1 is a diagram showing a schematic configuration of the inkjet printing apparatus 1 according to the present embodiment. The inkjet printing apparatus 1 includes a paper feeding section 10, an image forming section 20, a paper discharging section 30, and a control section 40.

[0017] Under the control of the control section 40, the inkjet printing apparatus 1 conveys the recording medium P stored in the paper feeding section 10 to the image forming section 20, ejects ink onto the recording medium P in the image forming section 20 to record an image, and conveys the recording medium P on which the image is recorded to the paper discharging section 30. Specifically, the inkjet printing apparatus 1 records a color image on the recording medium P by superimposing and outputting colors on the recording medium P at a predetermined number of recording gradations for each of the four colors of yellow (Y), magenta (M), cyan (C), and black (K). As the recording medium P, in addition to paper such as plain paper and coated paper, various media capable of fixing ink landed on the surface, such as fabric or sheet-shaped resin, can be used.

[0018] The paper feeding section 10 has a paper feeding tray 11 that stores the recording medium P, and a medium supply section 12 that conveys and supplies the recording medium P from the paper feeding tray 11 to the image forming section 20. The medium supply section 12 includes an annular belt whose inner side is supported by two rollers, and conveys the recording medium P from the paper feeding tray 11 to the image forming section 20 by rotating the rollers with the recording medium P placed on the belt.

[0019] The image forming section 20 has a conveying section 21, a transfer unit 22, a heating section 23, a head unit 24, an irradiation section 25, and a delivery section 26.

[0020] The conveying section 21 holds the recording medium P placed on the conveying surface of a cylindrical conveying drum (rotating drum portion) 211. In the conveying section 21, the conveying drum 211 rotates around a rotation axis (cylindrical axis) extending in the width direction of the recording medium P to perform orbital movement, so that the recording medium P on the conveying drum 211 is conveyed in the conveying direction along the conveying surface.

[0021] The transport drum 211 includes claws and an air intake (not shown) for holding the recording medium P on its transport surface. The recording medium P is held on the transport surface by its ends being pressed down by the claws and being drawn towards the transport surface by the air intake.

[0022] The transfer unit 22 is located between the media supply unit 12 and the transport unit 21 of the paper feeding unit 10. It holds one end of the recording medium P transported from the media supply unit 12 with the swing arm unit 221, picks it up, and transfers it to the transport unit 21 via the transfer drum 222.

[0023] The heating unit 23 is located between the position of the transfer drum 222 and the position of the head unit 24, and heats the recording medium P being transported by the transport unit 21 so that the recording medium P reaches a temperature within a predetermined range. The heating unit 23 has, for example, an infrared heater, and energizes the infrared heater based on a control signal supplied from the control unit 40 to generate heat.

[0024] The head unit 24 records an image by ejecting ink onto the recording medium P from the opening of a nozzle 243 located on the ink ejection surface facing the transport surface of the transport drum 211, at an appropriate timing corresponding to the rotation of the transport drum 211 in which the recording medium P is held. The ink ejected from the nozzle 243 onto the recording medium P hardens when irradiated with light. Specifically, it is an ink that has the property of hardening when irradiated with active rays (e.g., ultraviolet rays) (e.g., UV (ultraviolet) curable ink). UV ink contains an active ray polymerizable compound, and hardens when irradiated with active rays, as the active ray polymerizable compound polymerizes and crosslinks. Active ray curable ink may also contain, as needed, a polymerization initiator, a gelling agent, a polymerization inhibitor, colorants such as dyes and pigments, a dispersant for dispersing pigments, a fixing resin for fixing pigments to a substrate, a surfactant, a pH adjuster, a humectant, a UV absorber, etc.

[0025] The head unit 24 has a plurality of inkjet heads 240, which are arranged such that the ink (droplet) ejection surface and the transport surface of the inkjet heads 240 are separated by a predetermined distance. The inkjet heads 240 eject ink that hardens upon irradiation with an active ray onto the recording medium P.

[0026] In the inkjet printing apparatus 1 of this embodiment, four head units 24, each corresponding to one of the four ink colors Y, M, C, and K, are arranged at predetermined intervals from the upstream side in the transport direction of the recording medium P, in the order of the colors Y, M, C, and K. In other words, each head unit 24 is configured to eject multiple different types of ink.

[0027] In the inkjet printing apparatus 1, the head unit 24 is used in a fixed position when recording an image, and records an image in a single-pass manner by sequentially ejecting ink at predetermined intervals (transport direction intervals) at different positions in the transport direction in accordance with the transport of the recording medium P.

[0028] Figure 2 is a schematic diagram showing the configuration of the head unit 24 according to this embodiment. Figure 2 shows the surface of the head unit 24 that faces the outer circumferential surface of the transport drum 211.

[0029] Here, the head unit 24 comprises four inkjet heads 240 attached to a mounting member 244. Each inkjet head 240 is provided with multiple image forming elements, each having a pressure chamber (not shown) for storing ink, a piezoelectric element (not shown) provided on the wall of the pressure chamber, and a nozzle 243. When a drive signal is input to deform the piezoelectric element, the pressure chamber deforms due to the deformation of the piezoelectric element, changing the pressure inside the pressure chamber, and ink is ejected from the nozzle 243 that communicates with the pressure chamber.

[0030] The four inkjet heads 240 are arranged in a staggered pattern so that the arrangement range of the nozzle rows in the X direction (representing the direction perpendicular to the transport direction; the same applies hereinafter) is seamlessly connected. The arrangement range of the nozzles 243 included in the head unit 24 in the X direction covers the width in the X direction of the area on the recording medium P transported by the transport drum 211 where the image is formed. The head unit 24 is used fixed to the rotation axis of the transport drum 211 when forming an image. In other words, the head unit 24 constitutes a line head capable of ejecting ink over the image-forming width in the X direction relative to the recording medium P.

[0031] The inkjet head 240 is equipped with an ink heating unit (not shown) that heats the ink stored inside the inkjet head 240, and ejects the heated, sol-like ink. When this sol-like ink is ejected onto the recording medium P, the ink droplets land on the recording medium P, and then, due to natural cooling, the ink quickly turns into a gel and solidifies on the recording medium P.

[0032] The irradiation unit 25 has a light-emitting unit 252 (see Figure 4) that is arranged over a width perpendicular to the transport direction of the transport unit 21. The irradiation unit 25 irradiates the recording medium P placed on the transport drum 211 with active energy rays such as ultraviolet light from the light-emitting unit, thereby imparting a predetermined energy to the ink (gel ink) ejected onto the recording medium P, and curing and fixing the ink.

[0033] The irradiation unit 25 is positioned across the width of the transport unit 21 and irradiates the recording medium P placed on the transport unit 21 with electromagnetic waves (for example, ultraviolet light with a wavelength of 395 nm) to harden and fix the ink ejected onto the recording medium P.

[0034] The light-emitting part 252 of the irradiation unit 25 (see Figure 4) is positioned facing the transport surface in the transport direction, from the position of the head unit 24 to the position of the transfer drum 261 (delivery unit 26). The detailed configuration of the irradiation unit 25 will be described later.

[0035] The delivery unit 26 includes a belt loop 262 having a ring-shaped belt supported on the inside by two rollers, and 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 transports the recording medium P, which has been transferred from the transport unit 21 to the belt loop 262 by the transfer drum 261, and sends it to the paper discharge unit 30.

[0036] The paper output unit 30 has a plate-shaped paper output tray 31 on which the recording medium P sent out from the image forming unit 20 by the delivery unit 26 is placed.

[0037] Figure 3 is a block diagram showing the main functional configuration of the inkjet printing apparatus 1 according to this embodiment. The inkjet printing apparatus 1 includes a control unit 40, a head unit drive unit 50, a transport drive unit 60, an image processing unit 70, an input / output interface 80, an ink supply unit 90, a cooling device 110, a flow rate measurement unit 120, an irradiation unit 25, and an alarm unit 29.

[0038] The control unit 40 includes a CPU 41 (Central Processing Unit), RAM 42 (Random Access Memory), ROM 43 (Read Only Memory), and a storage unit 44, and comprehensively controls the overall operation of the printing device 1.

[0039] A flow rate measuring unit 120 is connected to the control unit 40, and the drive of the head unit 24 is controlled via the head unit drive unit 50 based on the flow rate (information regarding the flow rate) of the cooling medium circulating from the cooling device 110 to the irradiation unit 25. The cooling medium may be a liquid such as coolant or a cooling gas, as long as it can cool the light-emitting unit 252.

[0040] The control unit 40 controls each part according to the input print job to form an image on the recording medium P in accordance with the print job.

[0041] The control unit 40 controls the irradiation unit 25, which irradiates the ink ejected onto the recording medium P by the head unit 24 with energy rays.

[0042] The control unit 40 controls the cooling device 110, which is a chiller, to measure the flow rate of the cooling medium sent from the cooling device 110 to the irradiation unit 25, so that the irradiation unit 25 is not stressed by heating or overheating due to the operation. Based on the measured flow rate, the control unit 40 cools the irradiation unit 25 and prevents the temperature of the light-emitting unit 252, and consequently the irradiation unit 25 itself, from rising due to overheating caused by the irradiation drive.

[0043] The control unit 40 determines whether the chiller flow rate is a predetermined flow rate. The predetermined flow rate is the flow rate that cools the irradiation unit 25, more specifically the light-emitting unit 252 such as a UV LED, to a temperature where thermal stress is not applied. This prevents the elements of the light-emitting unit 252 such as a UV LED from deteriorating and shortening their lifespan.

[0044] The control unit 40 controls the overall image forming process, particularly the operation of the image forming unit 20, based on a predetermined flow rate. The control unit 40 controls the irradiation output of the irradiation unit 25 and controls the drive of the transport unit 21 and the head unit 24.

[0045] For example, if the chiller flow rate measured by the flow rate measuring unit 120 during printing is less than a predetermined flow rate, that is, if the flow rate is insufficient to adequately cool the light-emitting unit 252, the control unit 40 stops driving the irradiation unit 25, i.e., stops irradiation by the light-emitting unit 252. In other words, if the chiller flow rate is equal to or greater than the predetermined flow rate, that is, if the flow rate is sufficient to adequately cool the light-emitting unit 252, the control unit 40 continues the printing process. It also stops the ejection of ink by the head unit 24. The recording medium P from which the ink has been ejected may be held on the transport path (transport path section) under the control of the control unit 40. That is, the control unit 40 can temporarily hold the recording medium P on the transport path section and restart irradiation when the chiller flow rate returns to equal to or greater than the predetermined flow rate. As a result, the control unit 40 can prevent uncured ink from being transported within the image forming apparatus section 20, minimize the area inside the image forming section 20 that is contaminated by ink, and eliminate the need to clean the inside of the image forming section 20. Furthermore, it stops the paper feeding of the recording medium P by the paper feeding unit 10.

[0046] Furthermore, the control unit 40 can discharge the recording medium P remaining in the image forming unit 20 from the transport path.

[0047] Furthermore, based on information regarding the chiller flow rate obtained via the flow rate measurement unit 120, the control unit 40 controls the drive of the transport drum 211 via the transport drive unit 60 in particular to reduce the transport speed of the recording medium P.

[0048] The head unit drive unit 50 supplies a drive signal corresponding to the image data to the recording elements of the head unit 24 at an appropriate timing based on the control of the control unit 40. As a result, the head unit drive unit 50 ejects an amount of ink from the nozzles 243 of the head unit 24 that corresponds to the pixel values ​​of the image data.

[0049] The transport drive unit 60, based on control signals supplied from the control unit 40, supplies a drive signal to the transport drum motor provided on the transport drum 211, causing the transport drum 211 to rotate at a predetermined speed and timing. The transport drive unit 60 also supplies drive signals to motors that operate the medium supply unit 12, the transfer unit 22, and the delivery unit 26, based on control signals supplied from the control unit 40, causing the recording medium P to be supplied to the transport unit 21 and discharged from the transport unit 21.

[0050] The image processing unit 70 performs predetermined image processing on the image data input from the input / output interface 80 and stores the obtained image data in the storage unit 44. This image processing includes correction processing to correct the image data, as well as color conversion processing, gradation correction processing, and pseudo-halftone processing.

[0051] The input / output interface 80 is connected to the input / output interface of an external device (e.g., a personal computer) and mediates the transmission and reception of data between the control unit 40 and the external device. The input / output interface 80 is composed of, for example, various serial interfaces, various parallel interfaces, or a combination thereof.

[0052] The ink supply unit 90 supplies ink stored in an ink tank (not shown) to each of the multiple inkjet heads 240 provided on the head unit 24. The ink supply unit 90 adjusts the amount of ink supplied to each of the multiple inkjet heads 240 according to a control signal from the control unit 40.

[0053] The notification unit 29 notifies the user of the printing status of the inkjet printer 1, and is composed of, for example, a speaker that generates sound or a display that shows images. Alternatively, the notification unit 29 may use an operation panel for inputting print jobs. The notification unit 29 notifies the user of control information for the image forming unit 20 based on the flow rate of the cooling medium, via the control unit 40. Specifically, the notification unit 29 informs the user of the fact that the flow rate of the cooling medium is not sufficient to cool the light-emitting unit 252, or of the operation process of the image forming unit 220 as a result.

[0054] [Cooling mechanism for irradiation unit 25] Figure 4 is a schematic diagram showing the main components of a printing apparatus according to one embodiment of the present invention, and shows the main components of the cooling mechanism of the irradiation section of an inkjet printing apparatus. The cooling mechanism is a mechanism that suppresses heat generation caused by the operation of the irradiation unit 25, enabling irradiation operation and optimal irradiation output, thereby enabling optimal image forming processing.

[0055] The cooling mechanism includes a cooling unit 254 that cools the light-emitting unit 252 of the irradiation unit 25, a cooling device 110 connected to the cooling unit 254 and supplying a cooling medium to the cooling unit 254, a flow rate measuring unit 120, and a circulation path (flow channel). The circulation path connects the cooling unit 254 and the cooling device 110, allowing the cooling medium to flow from the cooling device 110 to the cooling unit 254 to cool the light-emitting unit 252. The cooling medium that has cooled the light-emitting unit 252 returns from the cooling unit 254 to the cooling device 110 and circulates through the circulation path.

[0056] The cooling device 110 supplies the cooling medium to the cooling unit 254 via the circulation path. The circulation path connects the cooling device 110 and the cooling unit 254, and circulates the cooling medium cooled by the cooling device 110 to the cooling unit 254, and then returns it from the cooling unit 254 to the cooling device 110.

[0057] In the circulation path, a flow rate measuring unit 120 is provided on the way back from the cooling unit 254 to the cooling device 110.

[0058] The flow rate measuring unit 120 measures the flow rate of the cooling medium that flows through the installed circulation path and cools the irradiation unit 25, and outputs it to the control unit 40 as chiller flow rate information. The cooling medium is, for example, a liquid, and the light-emitting unit 252 is cooled by water cooling. Since the flow rate measuring unit 120 is located downstream of the irradiation unit 25 in the annular path of the cooling medium, it can measure the temperature when the light-emitting unit 252 is actually cooled, and can detect the state of the light-emitting unit 252 in a timely manner.

[0059] The irradiation unit 25 is configured such that a UV LED or the like is used as the light-emitting unit 252, and the cooling unit 254 is configured to cool the UV LED with a cooling medium. For example, the cooling unit 254 is located adjacent to the light-emitting unit 252 and is a conduit with high thermal conductivity. By flowing a cooling medium inside it, it prevents the temperature of the heat-generating unit 252 from rising and lowers the temperature of the heat-generating unit 252 so that it does not generate heat.

[0060] The cooling medium that has absorbed the heat from the heat-generating section 252 returns to the cooling device 110 through the circulation path, is cooled again, and then sent to the cooling section 254.

[0061] The circulation path is composed of piping, for example, hoses and pipes.

[0062] Next, the drive control of the irradiation unit in the inkjet recording apparatus according to this embodiment will be described.

[0063] [Control of the image forming unit 20] The image forming unit 20, and in particular the irradiation unit 25, are controlled by the control unit 40 executing a program stored in the memory unit 44. For example, the memory unit 44 stores the temperature at which the light-emitting unit 252 experiences thermal stress due to heat generation, that is, the temperature at which degradation progresses and its lifespan is shortened. In addition, the flow rate of the cooling medium that can sufficiently cool the light-emitting unit 252 to prevent it from reaching these temperatures is stored in advance as a predetermined value, a first predetermined value, and a second predetermined value, depending on the paper size and basis weight.

[0064] As a result, the control unit 40 can measure the flow rate of the cooling medium and, if the flow rate is below a predetermined level, refrain from starting printing (by not controlling the illumination of the irradiation unit), thereby preventing a situation where the cooling medium is insufficient to cool the device.

[0065] Figure 5 is a flowchart illustrating the control of a printing apparatus according to one embodiment of the present invention. As shown in Figure 5, in step S11, the control unit 40 first initializes the settings for driving the irradiation unit 25 in the inkjet printing apparatus, such as measured values, and then drives each unit. For example, the control unit 40 drives each unit, namely the head unit drive unit 50, the transport drive unit 60, the image processing unit 70, the ink supply unit 90, etc., based on the print job.

[0066] In the cooling mechanism, the cooling device 110 and the irradiation unit 25 are driven, and the flow rate measurement unit 120 starts measuring the flow rate of the cooling medium flowing through the circulation path.

[0067] In step S12, the control unit 40 detects whether the flow rate of the cooling medium measured via the flow rate measuring unit 120 is equal to or greater than a predetermined value. The predetermined value is the flow rate that can reliably cool the light-emitting unit 252 of the irradiation unit 25.

[0068] In step S12, if the flow rate of the cooling medium supplied by the cooling device 110 to the irradiation unit 25 is equal to or greater than a predetermined value (YES), the control unit 40 determines that the flow rate of the cooling medium is sufficient to reliably cool the light-emitting unit 252, and proceeds to step S13. On the other hand, if the control unit 40 determines in step S12 that the measured flow rate of the cooling medium is less than a predetermined value (NO), it proceeds to step S14.

[0069] In step S13, the control unit 40 starts the printing process corresponding to the print job via each part in the image forming unit 20.

[0070] In step S14, the control unit 40 alerts the user regarding the flow rate, that is, that the flow rate is insufficient to cool the light-emitting unit 252. The control unit 40 alerts the user by sounding or displaying the error, for example, using a sound-emitting unit (speaker) or a display unit (not shown).

[0071] Furthermore, the control unit 40 may stop processing, image formation, ink curing, etc. in the image forming unit 20 after an error is reported. Alternatively, the control unit 40 may report an error by stopping processing, image formation, ink curing, etc. in the image forming unit 20.

[0072] Figure 6 is a flowchart illustrating another control method for a printing apparatus according to one embodiment of the present invention.

[0073] As shown in Figure 6, in step S21, first, the settings for driving the irradiation unit 25 in the inkjet printing device, such as measured values, are initialized and each unit is driven. For example, the control unit 40 drives each unit, namely the head unit drive unit 50, the transport drive unit 60, the image processing unit 70, the ink supply unit 90, etc., based on the print job.

[0074] In the cooling mechanism, the cooling device 110 and the irradiation unit 25 are driven, and the flow rate measurement unit 120 starts measuring the flow rate of the cooling medium flowing through the circulation path.

[0075] In step S22, the control unit 40 detects, via the flow rate measuring unit 120, whether the flow rate of the cooling medium is equal to or greater than a first predetermined amount indicated by a first predetermined value.

[0076] The first predetermined value (first predetermined amount) is a value that indicates a flow rate that can reliably cool the light-emitting part 252 of the irradiation unit 25. Immediately after the start of printing, the light-emitting part 252 is not in operation at the start of its drive, and the temperature of the light-emitting part 252 itself is low. In other words, it takes longer for the temperature of the light-emitting part 252 to reach a temperature at which it experiences thermal stress compared to when it is in operation, and therefore cooling is not necessary. For this reason, the first predetermined value is a value that indicates a flow rate that is less than the flow rate of the cooling medium required to cool the cooling medium to a temperature at which it experiences thermal stress during operation, and even if the light-emitting part 252 is cooled with a small flow rate, heating or overheating can be suppressed.

[0077] In step S22, if the flow rate of the cooling medium is equal to or greater than a predetermined value (YES), the control unit 40 determines that the flow rate of the cooling medium is sufficient to reliably cool the light-emitting unit 252 and proceeds to step S23. If it is less than the predetermined value (NO), proceeds to step S24.

[0078] In step S23, the control unit 40 starts the printing process corresponding to the print job via each unit in the image forming unit 20, and then proceeds to step S25.

[0079] In step S24, the control unit 40 alerts the user regarding the flow rate, specifically that the flow rate is insufficient to cool the light-emitting unit 252. The control unit 40 alerts the user by sounding and displaying the error, for example, using a sound-emitting unit (speaker) (not shown) or a display panel (not shown).

[0080] In step S24, the control unit 40 may stop processing, image formation, ink curing, etc. in the image forming unit 20 after issuing an error alert. Alternatively, the control unit 40 may issue an error alert by stopping processing, image formation, ink curing, etc. in the image forming unit 20.

[0081] In step S25, the control unit 40 detects, via the flow rate measuring unit 120, whether the flow rate of the cooling medium is equal to or greater than a second predetermined amount, which indicates a second predetermined value.

[0082] The second predetermined value (second predetermined amount) is a flow rate that can reliably cool the light-emitting part 252 of the irradiation unit 25 after the start of the printing process. This is a flow rate that cools the light-emitting part 252 at a predetermined flow rate value that is greater than the previously set predetermined flow rate value when the irradiation unit 25 is driven to heat or overheat after the start of printing and during printing.

[0083] For example, the irradiation unit 25 is a value that indicates the flow rate of the cooling medium that does not generate heat and rise in temperature according to the number and size (paper size) of the recording medium P.

[0084] The determination using a second predetermined value indicating a second predetermined amount controls the irradiation unit 25, i.e., the light-emitting unit 252, to prevent heating or overheating in cases such as when the flow rate is greater than or equal to the second predetermined amount after a predetermined time, or when the flow rate is greater than or equal to the predetermined amount within a predetermined number of printed sheets.

[0085] In other words, in step S25, the control unit 40 determines whether the measured flow rate of the cooling medium is equal to or greater than the flow rate indicated by a second predetermined value which is equal to or greater than the first predetermined amount indicated by the first predetermined value. In step S25, if the flow rate of the cooling medium is equal to or greater than the second predetermined value (YES), the control unit 40 determines that the flow rate of the cooling medium is sufficient to reliably cool the light-emitting unit 252. In step S25, if the control unit 40 determines that the flow rate is less than the predetermined value (NO), the process proceeds to step S24.

[0086] In step S26, the control unit 40 continues the printing process corresponding to the print job via each part in the image forming unit 20, and then proceeds to step S27.

[0087] In step S27, the control unit 40 determines whether the number of pages to be printed has been completed. If it has been completed, it terminates the print job. If the number of pages to be printed has not been completed, it returns to step S25 and repeats the process.

[0088] The light-emitting unit 252 cools down and lowers its temperature by intermittently lighting up or turning off when the paper size is small or the number of printed pages is small.

[0089] The control unit 40 can reduce the flow rate of the cooling medium supplied to the cooling unit 254 in order to cool the light-emitting unit 252 when its temperature has dropped, depending on the time, number of sheets, or the size of the paper.

[0090] In this manner, the control unit 40 drives each part of the image forming unit 20 based on the flow rate of the cooling medium that reliably cools the light-emitting unit 252, according to the time, number of sheets, or paper size.

[0091] When the power supply to the image forming unit 20 is ON, that is, when power is supplied to the image forming unit 20 and it is in a state where it can be driven, the control unit 40 continuously measures the flow rate of the cooling medium using the flow rate measuring unit 120 and controls the operation of the image forming unit 20 based on the measured flow rate.

[0092] Furthermore, the control unit 40 may control the operation of the inkjet printing apparatus 1 based on the acquired information regarding the flow rate of the cooling medium in response to the inkjet printing apparatus 1 starting image formation processing. Alternatively, the control unit 40 may acquire information regarding the flow rate of the cooling medium while the inkjet printing apparatus 1 is performing image formation processing and control the operation of the inkjet printing apparatus 1 based on that information.

[0093] The operations of the inkjet printing apparatus 1 based on the flow rate include the operation of the control unit 40 to issue an alert via the alarm unit 29, the operation to stop the operation of the irradiation unit 25, that is, the operation to stop the irradiation of the light-emitting unit 252, and the following operations. The control unit 40 may perform control to prohibit the ejection of UV-curable ink from the nozzle 243 of the head unit 24 based on the acquired information regarding the flow rate of the cooling medium.

[0094] The control unit 40 may, based on the flow rate of the cooling medium acquired during the printing operation, for example, if the acquired flow rate is less than or equal to a predetermined amount indicated by a predetermined value of the flow rate, prohibit the ejection of UV-curable ink from the nozzle 243 of the head unit 24. At the same time, the control unit 40 may also stop the paper supply from the media supply unit 12 and hold the recording medium P remaining in the transport path in place. This allows printing to be resumed by appropriately driving each part of the image forming unit 20, such as driving the irradiation unit 25 to resume irradiation of the light-emitting unit 252, after the abnormality in the flow rate of the cooling medium has been resolved, that is, when the flow rate of the cooling medium has returned to above the predetermined flow rate. As a result, the recording medium P with uncured ink ejected is not transported in the image forming unit 20, uncured ink does not adhere to the inside of the image forming unit 20, and the inside of the image forming unit 20 does not become contaminated.

[0095] The control unit 40 may reduce the transport speed of the recording medium P by the transport drum 211, which acts as a transport unit, according to the flow rate of the cooling medium. If the output control of the irradiation unit 25 (light-emitting unit 252) is reduced, the ink on the recording medium P will not harden if the transport speed remains the same.

[0096] Therefore, by reducing the transport speed of the recording medium P by the transport drum 211, the irradiation time (integrated light amount) to the ink can be secured. For example, if a small amount of cooling medium leakage occurs, the control unit 40 changes the control by reducing the output control of the irradiation unit 25 so that thermal stress is not applied to the light-emitting unit 252 such as the UV LED.

[0097] Furthermore, the control unit 40 prohibits the transport of recording media downstream of the transport drum 211 based on the flow rate of the cooling medium. If the measured flow rate of the cooling medium is not sufficient to cool the light-emitting unit 252 to a temperature that does not cause thermal stress, the control unit 40 controls the transport drum 211 to stop the transport of recording media downstream of the transport drum 211. In addition, the control unit 40 controls the irradiation output of the light-emitting unit 252. This prevents recording media P with uncured ink ejected from being output as an unfinished product and prevents it from being output as a finished product.

[0098] Furthermore, when the control unit 40 prohibits the transport of the recording medium P downstream of the transport drum 211, it may continue the rotation of the transport drum 211 for a predetermined time. This prevents the recording medium P, which has uncured ink, from flowing downstream and contaminating the transport path, etc.

[0099] According to the inkjet printing apparatus 1, after detecting that the light-emitting part 252, such as the UV LED of the illumination unit 25, is being adequately cooled, printing is started and the ink is cured, thereby preventing deterioration of the light-emitting part 252 (UV LED) and enabling satisfactory printing.

[0100] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above. [Industrial applicability]

[0101] According to the inkjet printing apparatus of this disclosure, deterioration of the irradiation area can be prevented, and image forming processing can be performed suitably. [Explanation of Symbols]

[0102] 1. Inkjet printing device 10 Paper feed section 12 Media supply section 20 Image forming unit 21 Conveying section 24 Head Units 25 Irradiation area 29. Reporting Department 30 Paper output section 40 Control Unit 50 Head unit drive unit 60 Conveyor drive unit 70 Image Processing Unit 80 Input / Output Interfaces 90 Ink supply unit 110 Cooling device 120 Flow rate measurement unit 211 Conveyor drum (rotating cylinder) 240 inkjet heads 243 Nozzles 252 Light-emitting part 254 Cooling section

Claims

1. An image forming unit including an inkjet head that ejects ink that hardens upon irradiation with an active ray onto a recording medium, and an irradiation unit that hardens the ink by irradiating it with an active ray, A flow rate measuring unit for measuring the flow rate of the cooling medium used to cool the irradiation unit, A control unit that controls the image forming unit based on the measured flow rate, control Inkjet printing device.

2. When the image forming unit is powered and operational, the control unit continuously measures the flow rate via the flow rate measuring unit. The inkjet printing apparatus according to claim 1.

3. The control unit measures the flow rate and controls the image forming unit in response to the start of image processing in the image forming unit. The inkjet printing apparatus according to claim 1.

4. The control unit measures the flow rate and controls the image forming unit while the image forming unit is performing image forming processing. The inkjet printing apparatus according to claim 1.

5. The control unit stops the ejection of the ink from the inkjet head based on the flow rate. The inkjet printing apparatus according to claim 1.

6. A supply unit that supplies the recording medium to the inkjet head, A transport unit for transporting the recording medium, The transport unit includes a transport path that transports the recording medium in the order of the supply unit, the inkjet head, and the irradiation unit, The control unit stops the ejection of the ink based on the flow rate, stops the supply of the recording medium from the supply unit to the inkjet head, and holds the recording medium remaining in the transport path via the transport unit. The inkjet printing apparatus according to claim 5.

7. The control unit reduces the transport speed of the recording medium from the inkjet head to the irradiation unit based on the flow rate, The inkjet printing apparatus according to claim 6.

8. The transport unit includes a rotating cylinder that places the recording medium on its outer surface and rotates, transporting the recording medium from the supply unit to the inkjet head and then to the irradiation unit in that order. The control unit stops transporting the recording medium from the supply unit based on the flow rate. The inkjet printing apparatus according to claim 7.

9. The control unit continues the rotation of the rotating drum for a predetermined time based on the flow rate. The inkjet printing apparatus according to claim 8.

10. The flow rate measuring unit measures the flow rate of the cooling medium after the irradiation unit has been cooled. The inkjet printing apparatus according to claim 1.

11. It has an alarm unit that alerts the user, The control unit controls the image forming unit based on the flow rate and notifies the user via the notification unit. The inkjet printing apparatus according to claim 1.

12. The control unit controls the irradiation output from the irradiation unit according to the flow rate during printing. The inkjet printing apparatus according to claim 10.

13. An inkjet printing apparatus has a computer comprising an inkjet head that ejects ink that hardens upon irradiation with an active ray onto a recording medium, an image forming unit that includes an irradiation unit that hardens the ink by irradiating it with an active ray, and a flow rate measuring unit that measures the flow rate of a cooling medium that cools the irradiation unit, The process of controlling the image forming unit based on the measured flow rate is executed. program.

14. In an inkjet printing apparatus having an inkjet head that ejects ink cured by irradiation with an active ray onto a recording medium, and an image forming unit that includes an irradiation unit for curing the ink by irradiating it with an active ray, The flow rate measuring unit measures the flow rate of the cooling medium that cools the irradiation unit. The image forming unit is controlled based on the measured flow rate. A method for controlling the image forming unit.

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