Droplet ejection device, program, and image forming system

Abstract

To provide a droplet discharge device, a program, and an image forming system capable of detecting sufficient coating with a pretreatment agent while efficiently executing image recording.SOLUTION: A droplet discharge device 1 comprises: an image forming unit 12 that discharges droplets to a recording surface P1 coated with a pretreatment agent for preventing infiltration of the droplets to form an image; a detection unit 13 that detects the density of a conveyance surface P2 during conveyance of a recording medium P image-formed by the image forming unit 12, which is a surface opposite the recording surface P1 during conveyance of the recording medium P image-formed by the image forming unit 12; and a control unit 15 serving as a determination unit that determines whether the recording surface P1 has been normally coated with the pretreatment agent on the basis of the density of the conveyance surface P2 detected by the detection unit 13.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a droplet ejection device, a program, and an image forming system.

Background Art

[0002] Conventionally, a droplet ejection device that ejects droplets onto a recording surface of a recording medium to record an image has been known. In such a droplet ejection device, droplets are ejected from nozzles of a droplet ejection head at an appropriate timing onto a recording surface coated with a pretreatment agent for preventing penetration of the droplets.

[0003] As shown in FIG. 10A, when droplets are ejected onto a recording medium with the pretreatment agent sufficiently applied to the recording surface, the droplets stay on the recording surface and a clear image can be formed. On the other hand, as shown in FIG. 10B, when droplets are ejected onto a recording medium with the pretreatment agent not sufficiently applied to the recording surface, the droplets do not stay on the recording surface and penetrate to the conveyance surface on the opposite side. As a result, the density of the image formed on the recording surface decreases and the quality deteriorates. Therefore, it is necessary to detect whether the pretreatment agent is sufficiently applied to the recording surface before the image recording operation. However, since the pretreatment agent is colorless and transparent, it is difficult to detect it visually.

[0004] Thus, a droplet ejection device is known that includes a light emitting element and a light receiving element and detects the presence or absence of nozzle defects based on whether a light beam is blocked by the ejected droplets (see, for example, Patent Document 1). With such a droplet ejection device, when the pretreatment agent is ejected and applied from the nozzles, it is possible to detect whether the pretreatment agent is sufficiently applied to the recording surface. Also, a droplet ejection device is known that reverses the printed paper and measures the reverse side density with a CCD (see, for example, Patent Document 2). With such a droplet ejection device, it is possible to detect whether the pretreatment agent is normally applied based on the measured reverse side density.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2006-240119 [Patent Document 2] Japanese Patent Publication No. 2007-130924 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, the droplet ejection device described in Patent Document 1 detects ejection failures by moving the carriage outside the printing area before ejecting droplets. As a result, productivity decreases due to this movement. Furthermore, the droplet ejection device described in Patent Document 2 measures the density of ink transfer to the back side by inverting the paper via an inversion path after single-sided printing. Therefore, it is inefficient in terms of productivity because the paper must be inverted even though it is only single-sided printing. In addition, it is inefficient in terms of cost because it requires a transport path that inverts the paper.

[0007] This invention has been made in view of the above circumstances. Its objective is to provide a droplet dispensing device, a program, and an image forming system that can efficiently detect defects in the application of a pretreatment agent. [Means for solving the problem]

[0008] To solve the above problems, the invention described in claim 1 is a droplet dispensing device, An image forming unit that forms an image by ejecting droplets onto the recording surface of a recording medium coated with a pretreatment agent to prevent droplet penetration, A detection unit that detects the density of the transport surface of the recording medium, which has an image formed on it by the image forming unit, on the surface opposite to the recording surface, The system includes a determination unit that determines whether the pretreatment agent has been properly applied to the recording surface based on the concentration of the transport surface detected by the detection unit.

[0009] The invention described in claim 2 is a droplet dispensing device according to claim 1, The device includes a coating unit provided upstream of the image forming unit in the transport direction, for applying the pretreatment agent to the recording surface of the recording medium.

[0010] The invention described in claim 3 is a droplet dispensing device according to claim 2, The coating unit applies a pretreatment agent by discharge from a nozzle. The determination unit determines whether or not there is a nozzle defect in the coating portion.

[0011] The invention described in claim 4 is a droplet dispensing device according to any one of claims 1 to 3, The image forming unit comprises a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted. The image forming unit forms an image by scanning the carriage in a width direction perpendicular to the transport direction of the recording medium.

[0012] The invention described in claim 5 is a droplet dispensing device according to claim 4, The image forming unit forms a color band image by ejecting droplets from the droplet ejection head at the widthwise end of the image forming area of ​​the recording medium during image formation. The detection unit detects the density of the color band image on the transport surface side.

[0013] The invention described in claim 6 is a droplet dispensing device according to claim 5, The detection unit has a length greater than or equal to the length of the image scanned and printed by the carriage.

[0014] The invention described in claim 7 is a droplet dispensing device according to any one of claims 1 to 3, The image forming unit comprises a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted. The image forming unit forms an image by fixing the carriage.

[0015] The invention described in claim 8 is a droplet dispensing device according to claim 7, Before starting the recording operation, the image forming unit discharges droplets from the droplet discharge head to form a ribbon image. The detection unit detects the density on the conveyance surface side of the ribbon image.

[0016] The invention according to claim 9 is a droplet discharge device according to claim 8, The detection unit is provided below an extension line in the conveyance direction of the image forming unit such that a length in a width direction orthogonal to the conveyance direction of the recording medium is the same as a length in the width direction of an image forming area of the recording medium.

[0017] The invention according to claim 10 is a droplet discharge device according to any one of claims 1 to 3, When the density of the conveyance surface detected by the detection unit is equal to or greater than a predetermined threshold value, the determination unit determines that an application defect of the pretreatment agent has occurred.

[0018] The invention according to claim 11 is a droplet discharge device according to claim 10, The device includes an operation reception unit capable of arbitrarily setting the threshold value.

[0019] The invention according to claim 12 is a droplet discharge device according to claim 10, The threshold value varies depending on the type of the recording medium.

[0020] The invention according to claim 13 is a droplet discharge device according to claim 10, When the determination unit determines that an application defect of the pretreatment agent has occurred, the device includes a control unit that interrupts image formation and notifies a user of a warning.

[0021] The invention according to claim 14 is a droplet discharge device according to claim 10, which cites claim 3, a cleaning unit that cleans a discharge surface of the image forming unit and the application unit; When the determination unit determines that an application defect of the pretreatment agent has occurred, the device includes a control unit that interrupts image formation and causes the cleaning unit to clean the discharge surface of the application unit.

[0022] The invention described in claim 15 is a droplet dispensing device according to any one of claims 1 to 3, The recording medium is made of cloth.

[0023] The invention described in claim 16 is a droplet dispensing device according to any one of claims 1 to 3, The detection unit comprises a light source that irradiates light onto the transport surface of the recording medium, and a light receiving unit that receives the reflected light irradiated by the light source and reflected off the transport surface. The density of the transport surface is detected from the intensity of the reflected light received by the light-receiving unit.

[0024] The invention described in claim 17 is a program, A computer for a droplet ejection device comprising: an image forming unit that ejects droplets to form an image on the recording surface of a recording medium coated with a pretreatment agent to prevent droplet penetration; and a detection unit that detects the density of the transport surface on the opposite side of the recording medium from the recording surface during transport of the recording medium on which the image has been formed by the image forming unit, Based on the concentration of the transport surface detected by the detection unit, it functions as a determination unit that determines whether the pretreatment agent has been properly applied to the recording surface.

[0025] The invention described in claim 18 is an image forming system, A droplet dispensing device according to claim 1, The system includes a coating apparatus equipped with a coating section for applying a pretreatment agent to the recording surface of a recording medium. [Effects of the Invention]

[0026] According to the present invention, it is possible to efficiently detect defects in the application of pretreatment agents. [Brief explanation of the drawing]

[0027] [Figure 1] This is a block diagram of a droplet dispensing device and a coating device in an image forming system according to the first embodiment. [Figure 2]This is a side view of the droplet ejection device in the image forming system according to the first embodiment. [Figure 3] This is a bottom view showing an example of a detection unit. [Figure 4A] This graph shows the amount of ink and the changes in ink concentration on the recording surface and transport surface when ink is ejected onto a recording medium on which the pretreatment agent has been properly applied to the recording surface. [Figure 4B] This graph shows the amount of ink and the changes in ink concentration on the recording surface and transport surface when ink is ejected onto a recording medium that has not been coated with a pretreatment agent. [Figure 5] This is a flowchart showing the operation flow of the droplet dispensing device in the image forming system according to the first embodiment. [Figure 6] This is a block diagram of the droplet dispensing device in the image forming system according to the second embodiment. [Figure 7] This is a side view of the droplet ejection device in the image forming system according to the second embodiment. [Figure 8] This is a flowchart showing the operation flow of the droplet dispensing device in the image forming system according to the second embodiment. [Figure 9] This is a bottom view showing an example of a detection unit related to a modified example. [Figure 10A] This is a schematic diagram of a recording medium on which droplets are ejected onto a recording surface coated with a pretreatment agent. [Figure 10B] This is a schematic diagram of a recording medium in which droplets are ejected onto a recording surface that has not been coated with a pretreatment agent. [Modes for carrying out the invention]

[0028] One embodiment of the present invention will be described below with reference to the drawings. The following description is illustrative of one embodiment of the present invention and does not limit it.

[0029] [Overall configuration of the image forming system] [First Embodiment] Figure 1 is a block diagram showing the functional configuration of the inkjet recording device 1 and the coating device 2. Figure 2 is a side view of the inkjet recording device 1. The image forming system 100 includes at least an inkjet recording device 1, which is a droplet ejection device. As shown in Figure 1, the image forming system 100 according to this embodiment comprises an inkjet recording device 1 and a coating device 2. In other words, the image forming system 100 according to this embodiment employs a pre-coating method for a pre-treatment agent.

[0030] [Inkjet recording device] First, an example configuration of the inkjet recording device 1 is disclosed. The inkjet recording device 1 is a device that forms an image by ejecting ink from an inkjet head 121, which is a droplet ejection head, onto a recording surface P1, which is one side of the recording medium P.

[0031] The inkjet recording apparatus 1 according to the first embodiment includes a transport unit 11, an image forming unit 12, a detection unit 13, a cleaning unit 14, a control unit 15, a storage unit 16, a communication unit 17, an operation reception unit 18, and a display unit 19.

[0032] (Recording medium) In this invention, the recording medium P is, for example, a cloth. However, the recording medium P is not limited to a cloth, and may be paper or other materials. Furthermore, in this embodiment, the recording medium P is pre-treated by a coating device 2 before being loaded into the inkjet recording device 1, and a pre-treatment agent is applied to the recording surface P1.

[0033] (Pretreatment agent) The ink ejected by the image forming unit 12 has a low viscosity so that it can be ejected as droplets from the nozzle. Therefore, when ink is ejected onto the recording medium P, the ink may not remain on the recording surface P1 but may penetrate to the transport surface P2, which is the opposite side of the recording surface P1. This results in a lower density of the image formed on the recording surface P1, leading to poor quality. In contrast, applying a pre-treatment agent that prevents ink penetration to the recording surface P1 allows the ink to remain on the recording surface P1, enabling the recording of a clear image.

[0034] The pretreatment agent may be any appropriate component depending on the ink ejected from the image forming unit 12. For example, in the case of reactive ink or dispersible ink, it is preferable to apply a liquid containing an adhesive as a pretreatment agent to keep the ink on the recording surface P1. In the case of dry process ink containing pigment, it is preferable to use an acidic liquid as a pretreatment agent to aggregate the anionic groups in the ink.

[0035] Furthermore, the amount of pretreatment agent applied (thinning ratio) depends on the type of recording medium P, but can be, for example, 0.2% to 90% by mass relative to the total mass of the recording medium P.

[0036] (Transportation section) The transport unit 11 includes, for example, two transport rollers 111, a transport belt 112, and a transport motor 113. The transport unit 11 transports the recording medium P in the transport direction.

[0037] The conveyor roller 111 rotates in the conveying direction around a rotation axis that extends in the width direction perpendicular to the conveying direction. The conveyor roller 111 also supports the inside of the ring-shaped conveyor belt 112. The conveying surface P2 of the recording medium P is placed on the conveying surface of the conveyor belt 112 so as to be in contact with it. When the conveyor roller 111 rotates in accordance with the operation of the conveyor motor 113, the conveyor belt 112 moves in a circular motion in the conveying direction, conveying the recording medium P in the conveying direction shown by the arrow in Figure 2.

[0038] (Image forming unit) Returning to Figure 1, the image forming unit 12 comprises an inkjet head 121, a head drive unit 122, and a carriage C. The image forming unit 12 ejects ink onto the recording surface P1 to form an image.

[0039] The inkjet head 121 comprises a number of nozzles arranged in a predetermined pattern that eject ink from their openings, and a piezoelectric element.

[0040] Furthermore, multiple inkjet heads 121 are arranged on a fixed carriage C to constitute an inkjet head unit. The widthwise length of the image-forming area of ​​the inkjet head unit (i.e., the length from the nozzle at the first end to the nozzle at the second end in the widthwise direction of the inkjet head unit) is approximately the same as the widthwise length of the image-forming area of ​​the recording medium P. In other words, the inkjet recording apparatus 1 according to this embodiment is a so-called one-pass type inkjet recording apparatus.

[0041] The head drive unit 122 outputs drive pulses that expand or contract the piezoelectric elements of each inkjet head 121 based on the control of the control unit 15. As the piezoelectric elements deform due to the drive pulses, they deform the ink flow path (pressure chamber) that supplies ink to the nozzle, thereby imparting pressure fluctuations to the ink and causing ink to be ejected from the nozzle.

[0042] Although not shown in Figure 2, the image forming unit 12 may have multiple inkjet head units in the transport direction. Each inkjet head unit may eject ink of a different color, such as Y (yellow), M (magenta), C (cyan), K (black), spot colors, or light colors. Alternatively, multiple inkjet head units may eject ink of the same color.

[0043] (Detection unit) The detection unit 13 is provided, for example, as shown in Figure 3, below the extension of the transport direction of the image forming unit 12, so as to be of equal width to the image forming area. The detection unit 13 includes a plurality of density sensors 131 arranged along the width direction, which are capable of acquiring the density of the transport surface P2.

[0044] The concentration sensor 131 includes, for example, a light source 131a and a light receiving unit 131b. The concentration sensor 131 receives the reflected light from the light source 131a onto the transport surface P2 with the light receiving unit 131b and obtains the concentration of the transport surface P2 from the intensity of the reflected light. The detection unit 13 then outputs the concentration information of the transport surface P2 acquired by the concentration sensor 131 to the control unit 15.

[0045] Furthermore, the method for obtaining the density of the transport surface P2 using the density sensor 131 is not limited to a configuration that obtains reflected light intensity. For example, a light source 131a and a light receiving unit 131b may be provided at opposing positions on either side of the recording medium P to obtain transmitted light intensity, and the density of the transport surface P2 may be obtained from this transmitted light intensity.

[0046] Figure 4A is a graph showing the relationship between the amount of ink and the concentration on the recording surface P1 (solid line) and the transport surface P2 (dotted line) when ink is ejected onto the recording surface P1 to which the pretreatment agent has been properly applied. Figure 4B is a graph showing the relationship between the amount of ink and the concentration on the recording surface P1 (thick dashed line) and the transport surface P2 (thin dashed line) when ink is ejected onto the recording surface P1 to which the pretreatment agent has not been applied.

[0047] As described above, in a recording medium P on which the pretreatment agent has been properly applied to the recording surface P1, the ink remains on the recording surface P1 and does not penetrate to the transport surface P2. Therefore, as shown in Figure 4A, the density of the recording surface P1 increases as the amount of ink increases. On the other hand, because the pretreatment agent inhibits ink penetration into the transport surface P2, the concentration on the transport surface P2 does not change even if the amount of ink is increased.

[0048] In contrast, in recording media P where a pretreatment agent is not applied to the recording surface P1, the ink does not remain on the recording surface P1 but penetrates to the transport surface P2. Therefore, as shown in Figure 4B, the density of the recording surface P1 increases as the amount of ink increases. However, the amount of increase is smaller compared to Figure 4A. Furthermore, as the amount of ink increases, the amount of ink absorbed also increases. Therefore, as the amount of ink increases, the density of the transport surface P2 also increases.

[0049] Thus, the density of the recording surface P1 increases, albeit at different rates, whether or not a pretreatment agent is applied. Therefore, simply detecting an increase in the density of the recording surface P1 within the image-forming region is insufficient to determine whether or not a pretreatment agent has been applied; it becomes necessary to create a predetermined grayscale chart image, such as a 100% image. As a result, real-time detection of abnormal pretreatment agent application in line with image formation becomes difficult.

[0050] On the other hand, the density of the transport surface P2 does not change from the areas where ink is not ejected if the pretreatment agent is applied correctly, and increases in proportion to the amount of ink if it is not applied correctly. Therefore, by obtaining the density of the transport surface P2, it is easier to detect whether or not there is abnormal application of the pretreatment agent on the recording surface P1 than by obtaining the density of the recording surface P1. In other words, since the creation of a gradation chart image becomes unnecessary, it becomes possible to detect in real time whether or not the pretreatment agent has been applied abnormally during image formation.

[0051] (Cleaning Department) Returning to Figure 1, the cleaning unit 14 comprises a drive unit 141 and a wiping member 142. The cleaning unit 14 cleans the ejection surface of the inkjet head 121 where the nozzle openings are arranged.

[0052] The drive unit 141 operates the wiping member 142 to wipe away ink and its solidified residue that has adhered to the discharge surface. The wiping member 142 is not particularly limited, but for example, it may be a nonwoven fabric that absorbs ink or a resin member on a blade that scrapes off solid material.

[0053] (Control Unit) The control unit 15 is a processor that provides overall control over the operation of the inkjet recording device 1. The control unit 15 includes, for example, a CPU 151 (Central Processing Unit) and RAM 152 (Random Access Memory).

[0054] The CPU 151 performs various control processes through arithmetic operations. The RAM 152 provides the CPU 151 with a working memory space and stores temporary data. Furthermore, the control unit 15 functions as a determination unit that, by executing a predetermined program, determines whether the pretreatment agent has been properly applied to the recording surface P1 based on the concentration of the transport surface P2 detected by the detection unit 13.

[0055] Specifically, the control unit 15 compares, for example, the density of the transport surface P2 below the image forming area, as detected by the density sensor 131, with a predetermined threshold based on the density of the transport surface P2 before image formation. If the density of the transport surface P2 is below the predetermined threshold, it determines that the pretreatment agent has been applied correctly and continues the recording operation. If the density of the transport surface P2 is above the predetermined threshold, it determines that there is a problem with the application of the pretreatment agent, displays a warning about the pretreatment agent application problem on the display unit 19, and interrupts the recording operation.

[0056] Furthermore, the predetermined threshold is not limited to those set in advance. For example, it may be changed to any value the user chooses through an operation of the operation reception unit 18. Furthermore, while it is preferable that the density of the transport surface P2 before image formation is stored in the storage unit 16 beforehand, this is not limited to this. For example, the recording medium P may be transported before image formation, and the density of the transport surface P2 may be acquired by the density sensor 131. Furthermore, it is preferable that different threshold values ​​corresponding to the type of recording medium P are stored in the storage unit 16.

[0057] (Storage part) The storage unit 16 stores the image data to be recorded, its processing data, and other setting data and programs. The image data may be stored, for example, in DRAM (Dynamic Random Access Memory) which can temporarily store a large amount of data and output it at high speed. The setting data and programs are stored in non-volatile memory such as flash memory and / or HDD (Hard Disk Drive). This allows the setting data to be stored even when the power supply to the inkjet recording device 1 is cut off.

[0058] (Communications Department) The communication unit 17 controls the transmission and reception of data according to a predetermined communication standard, such as TCP / IP (Transmission Control Protocol / Internet Protocol). The communication unit 17 may be connected to a LAN (Local Area Network) and be able to connect to the external internet via a router. Alternatively, the communication unit 17 may be able to connect directly to the external internet via a USB cable connected to a USB (Universal Serial Bus) terminal.

[0059] (Operation reception desk) The operation reception unit 18 receives input operations from the user and outputs the received content as an input signal to the control unit 15. The operation reception unit 18 may include, for example, a touch panel or a push-button switch. The touch panel may be positioned to overlap with the display screen of the display unit 19, and the operation content may be identified in synchronization with the content displayed on the display screen.

[0060] (Display) The display unit 19 displays the status and selection menus to the user. The display unit 19 includes, for example, a display screen and an indicator (lamp). The indicator may be used, for example, an LED (Light Emitting Diode) lamp to indicate whether power is being supplied or whether there is an operational abnormality. Furthermore, the display unit 19 may have, for example, a liquid crystal display, and may display various characters and figures on the display screen using a dot matrix display.

[0061] [Coating device] The coating apparatus 2 is a device for applying a pretreatment agent to the recording medium P. The coating apparatus 2 comprises a control unit 21 and a coating unit 22. The control unit 21, for example, includes a CPU and RAM, and controls the application of the pretreatment agent by the coating unit 22.

[0062] (Coated area) The coating unit 22 applies a pretreatment agent to the image forming area of ​​the recording surface P1. Examples of methods for applying the pretreatment agent using the coating unit 22 include the pad method, coating method, and spray method. The method for applying the pretreatment agent using the coating unit 22 is not limited to these, and any known method may be used as appropriate.

[0063] Note that while Figure 1 illustrates a case where the inkjet recording device 1 and the coating device 2 are systematically connected, the case is not limited to this.

[0064] [Inkjet recording device operation] Next, the operation of the inkjet recording apparatus 1 according to this embodiment will be described. Figure 5 is a flowchart showing the operation flow of the inkjet recording device 1.

[0065] When the inkjet recording device 1 receives an image recording instruction from the user via the operation reception unit 18, the inkjet recording device 1 transports the recording medium P by the continuous operation of the transport unit 11 (step S101). The recording medium P is a recording medium P on which a pretreatment agent has been applied in advance to the recording surface P1 by the coating device 2.

[0066] The control unit 15 determines whether the color band formation region of the recording medium P has reached below the image forming unit 12 (step S102). In this embodiment, the color band forming region is provided along the width direction at the downstream end of the image forming region in the transport direction. If the control unit 15 determines that the color band formation region has not reached below the image forming unit 12 (step S102; No), it returns to step S102. The control unit 15 then waits until the color band formation region reaches below the image forming unit 12.

[0067] If the control unit 15 determines that the color band formation area has reached below the image formation unit 12 (step S102; Yes), it causes the head drive unit 122 to output a drive pulse. Then, ink is ejected from all nozzles of the inkjet head unit into the color band formation area to form a color band image (step S103).

[0068] Because ink dries quickly, if a nozzle has not dispensed ink for a predetermined time, the ink evaporates and thickens internally. This results in a phenomenon called decapping, where the nozzle is unable to dispense ink, or if it can dispense ink, the dispensing speed decreases. To prevent this, good ink dispensing can be achieved by dispensing all the ink from the nozzles before forming the image based on the image recording instruction, thereby forming a color band image. In the following explanation, to distinguish it from a color band image, the image formed in the image formation region excluding the color band formation region based on the image recording instruction will be referred to as the recorded image.

[0069] After the color band image is formed, the control unit 15 determines whether the color band formation region has reached the detection unit 13 (step S104). If the control unit 15 determines that the color band formation area has not reached the detection unit 13 (step S104; No), it returns to step S104. The control unit 15 then waits until the color band formation area reaches the detection unit 13.

[0070] If the control unit 15 determines that the color band formation region has reached the detection unit 13 (step S104; Yes), it causes the density sensor 131 to acquire the density of the transport surface P2 below the color band formation region (step S105).

[0071] The control unit 15, acting as a determination unit, determines whether or not there is a pretreatment agent application defect based on the density of the transport surface P2 below the color band formation region acquired by the density sensor 131 (step S106). If the control unit 15 determines that there is a pretreatment agent application defect (step S106; Yes), it interrupts the image recording operation (step S107). The control unit 15 also displays a warning about the pretreatment agent application defect on the display unit 19 (step S108) and terminates the operation.

[0072] Note that it is not necessary to perform both steps S107 and S108. It is sufficient to perform at least one of them.

[0073] When low-density recorded images are formed, even if there is a defect in the application of the pretreatment agent, less ink may penetrate to the transport surface P2. As a result, the increase in density on the transport surface P2 may be small, and the defect in the application of the pretreatment agent may not be detected. In contrast, color band images have a high density, and if there is a defect in the application of the pretreatment agent, the increase in density on the transport surface P2 is large.

[0074] Thus, the transport surface P2 below the color band image allows for easier detection of whether or not there are defects in the application of the pretreatment agent. For this reason, it is preferable to detect the presence or absence of defects in the application of the pretreatment agent not only on the transport surface P2 below the recording image, but also on the transport surface P2 below the color band image. However, detecting whether or not there is a defect in the application of the pretreatment agent based on the density of the transport surface P2 below the color band image is not an essential operation in the inkjet recording device 1. Therefore, it is acceptable to transition from step S103 to step S109, which will be described later.

[0075] If the control unit 15 determines that there are no defects in the application of the pretreatment agent (step S106; No), it starts forming the recorded image (step S109). Specifically, the control unit 15 forms the recorded image on the recording surface P1 by ejecting ink from the image forming unit 12 based on the image data stored in the storage unit 16.

[0076] During the formation of the recorded image, the detection unit 13 sequentially acquires the density of the transport surface P2, and the control unit 15 determines from the density whether or not there is a defect in the application of the pretreatment agent (step S110). If the control unit 15 determines that there is a defect in the application of the pretreatment agent (step S110; Yes), it proceeds to step S107 or step S108 and terminates the operation.

[0077] If the control unit 15 determines that there are no defects in the application of the pretreatment agent (step S110; No), it determines whether the formation of the recorded image is complete (step S111). If the control unit 15 determines that the formation of the recorded image is not complete (step S111; No), it proceeds to step S109 and continues the formation of the recorded image. If the control unit 15 determines that the formation of the recorded image is complete (step S111; Yes), it terminates the recording operation. After the recording operation is completed, the recording medium P is dried by a dryer (not shown) and the recording medium P is stored by a winder (not shown).

[0078] [Effects of the First Embodiment] As described above, the inkjet recording apparatus 1 according to the first embodiment includes an image forming unit 12 that ejects droplets onto a recording surface P1 coated with a pretreatment agent to form an image. The inkjet recording apparatus 1 also includes a detection unit 13 that detects the density of the transport surface P2, which is the surface opposite to the recording surface P1, while the recording medium P on which the image has been formed by the image forming unit 12 is being transported. The inkjet recording apparatus 1 also includes a control unit 15 that determines whether the pretreatment agent has been properly applied to the recording surface P1 based on the density of the transport surface P2 detected by the detection unit 13. This configuration makes it easier to determine whether the pretreatment agent has been properly applied than when measuring the density of the recording surface P1. Therefore, it is possible to efficiently detect whether the pretreatment agent has been sufficiently applied.

[0079] Furthermore, the image forming unit 12 includes an inkjet head 121 that ejects droplets from a nozzle, and a carriage C on which the inkjet head 121 is mounted. The image forming unit 12 then fixes the carriage C and forms an image. In other words, the inkjet recording device 1 is a one-pass type. This configuration allows for high productivity because image formation is completed in a single, continuous scan.

[0080] Furthermore, the image forming unit 12 ejects droplets from the inkjet head 121 before the recording operation begins to form a color band image. The detection unit 13 then detects the density of the color band image on the transport surface P2 side. This configuration allows for the determination of whether or not there are defects in the application of the pretreatment agent before the formation of the recorded image, making it more efficient. Furthermore, it allows for the determination of whether or not there are defects in the application of the pretreatment agent regardless of the density of the recorded image. In addition, the formation of a color band image reduces nozzle dispensing defects.

[0081] Furthermore, the detection unit 13 is positioned below the extension of the image forming unit 12 such that its width is the same as the width of the image forming area of ​​the recording medium P. With this configuration, the detection unit 13 can detect the density of the transport surface P2 across the entire image forming region.

[0082] Furthermore, the control unit 15 determines that a pretreatment agent application defect has occurred if the concentration of the transport surface P2 detected by the detection unit 13 is above a predetermined threshold. This configuration prevents false detections caused by differences in concentration on the transport surface P2 that are not due to improper application of the pretreatment agent.

[0083] Furthermore, the inkjet recording device 1 includes an operation reception unit 18 that allows the threshold value to be set arbitrarily. This configuration allows for recording operations that correspond to the required image quality.

[0084] Furthermore, the storage unit 16 of the inkjet recording device 1 stores different threshold values ​​for each type of recording medium P. According to this configuration, various recording media P can be used with the inkjet recording device 1.

[0085] Furthermore, if the control unit 15 determines that there is a problem with the application of the pretreatment agent, it will interrupt image formation and notify the user of a warning. This configuration prevents the recording operation from continuing on a recording medium P that has a faulty application of the pretreatment agent, thus preventing increased costs.

[0086] [Second Embodiment] Next, the image forming system 100 according to the second embodiment will be described in detail with reference to Figures 6 to 8. In the following description, components similar to those in the image forming system 100 according to the first embodiment are denoted by the same reference numerals and their descriptions are omitted. The image forming system 100 according to the second embodiment comprises only an inkjet recording device 1 and does not include a coating device 2.

[0087] Figure 6 is a block diagram showing the functional configuration of the inkjet recording apparatus 1 according to the second embodiment. Figure 7 is a side view of the inkjet recording apparatus 1 according to the second embodiment. As shown in Figure 7, the inkjet recording apparatus 1 according to the second embodiment includes a coating unit 22 located upstream of the image forming unit 12 in the transport direction. In other words, the image forming system 100 according to the second embodiment employs an in-line pretreatment method.

[0088] (Coated area) The coating unit 22 applies a pretreatment agent to the recording medium P that has been transported by the transport unit 11. Specifically, the coating unit 22 has a configuration similar to that of an inkjet head unit, and applies a pretreatment agent to the recording medium P based on the drive pulses of the head drive unit 122.

[0089] [Operation of the droplet dispensing device] Next, the operation of the inkjet recording apparatus 1 according to the second embodiment will be described. Figure 8 is a flowchart showing the operation flow of the inkjet recording device 1.

[0090] Upon receiving an image recording instruction from the user, the inkjet recording device 1 transports the recording medium P using the transport unit 11 (step S201).

[0091] The control unit 15 determines whether the leading edge of the image-forming area of ​​the recording medium P has reached below the coating area 22 (step S202). If the leading edge of the image-forming area has not reached below the coating area 22 (step S202; No), the control unit 15 waits until the leading edge of the image-forming area reaches below the coating area 22.

[0092] When the leading edge of the image forming area reaches below the coating section 22 (step S202; Yes), the control unit 15 causes the head drive unit 122 to output a drive pulse to discharge the pretreatment agent (step S203).

[0093] The subsequent steps S204 to S213 are the same as steps S102 to S111 of the first embodiment, so a detailed explanation will be omitted.

[0094] Furthermore, if the control unit 15 interrupts the image recording operation in step S209, it may perform a process to clean the discharge surface of the coating unit 22 using the cleaning unit 14.

[0095] [Effects of the second embodiment] As described above, the inkjet recording apparatus 1 according to the second embodiment includes a coating unit 22 provided upstream of the image forming unit 12 in the transport direction. The coating unit 22 applies a pretreatment agent, for example, by ejection from a nozzle, and the control unit 15 determines whether or not there is a nozzle defect in the coating unit 22. With this configuration, a clear image can be recorded on a recording medium P coated with a pretreatment agent without needing to provide a separate coating device 2 in addition to the inkjet recording device 1.

[0096] Furthermore, the inkjet recording device 1 includes a cleaning unit 14 that cleans the ejection surfaces of the image forming unit 12 and the coating unit 22. When the control unit 15 determines that there is a problem with the application of the pretreatment agent, it interrupts image formation and causes the cleaning unit 14 to clean the ejection surface of the coating unit 22. According to this configuration, image formation can be resumed after the cleaning operation is completed.

[0097] [Other configurations] In the above description, it was stated that in step S202, the pretreatment agent is applied by the coating unit 22 when the leading edge of the image forming region reaches below the coating unit 22, but this is not limited to this. That is, the pretreatment agent may be applied by the coating unit 22 when the leading edge of the recording medium P reaches below the coating unit 22.

[0098] Furthermore, although the coating unit 22 of the second embodiment is described above as having the same configuration as the inkjet head unit, it is not limited to this. The coating unit 22 of the second embodiment may also be coated with a pretreatment agent using methods such as the pad method, coating method, or spray method, similar to the coating unit 22 of the coating apparatus 2 of the first embodiment.

[0099] Furthermore, in the above description, the width of the image-forming area of ​​the inkjet head unit is approximately the same as the width of the image-forming area of ​​the recording medium P, and the carriage C is fixed in a single-pass configuration, but the invention is not limited to this configuration. The widthwise length of the image-forming area of ​​the inkjet head unit is shorter than the widthwise length of the image-forming area of ​​the recording medium P, and the carriage C may be movable in the widthwise direction. In other words, the inkjet recording device 1 may be a so-called scanning type, which performs the recording operation by moving the carriage C in the width direction.

[0100] In the scanning inkjet recording device 1, the transport unit 11 does not transport the recording medium P by continuous operation, but rather by intermittent operation. Specifically, for example, each time the carriage C moves from the first end to the second end in the width direction of the image forming area to form an image, the transport unit 11 transports the recording medium P a predetermined distance in the transport direction.

[0101] Furthermore, in the scanning-type inkjet recording device 1, the color band formation region is the first end in the width direction of the image formation region of the recording medium P. The color band formation operation is performed during image formation, not before the recording operation.

[0102] Furthermore, in the scanning-type inkjet recording device 1, the detection unit 13 does not need to be of the same width as the image forming area. The detection unit 13 only needs to be at least as long as the length of the image scanned and printed by the carriage C. With this configuration, when the image forming unit 12 performs image formation, it is possible to detect defects in the application of the pretreatment agent. Furthermore, as shown in Figure 9, the system may not have multiple concentration sensors 131, but instead have only one concentration sensor 131.

[0103] Furthermore, although the image forming system 100 is configured to include an inkjet recording device 1 and a coating device 2 as described above, it is not limited to this configuration. For example, it may also include other devices having configurations such as an operation reception unit 18 and a display unit 19.

[0104] Furthermore, although the above example illustrates the case where the inkjet recording device 1 performs single-sided printing, it is not limited to this. The inkjet recording device 1 may also perform double-sided printing. Furthermore, when the inkjet recording device 1 forms a recorded image on the first surface of the recording medium P, and then inverts the recording medium P to form a recorded image on the second surface, it goes without saying that the second surface becomes the recording surface P1 and the first surface becomes the transport surface P2.

[0105] Furthermore, although the droplet ejection head 121 was described as an inkjet head in the above description, the droplets ejected from the droplet ejection head 121 are not limited to ink droplets.

[0106] Furthermore, while examples of using hard disks, semiconductor non-volatile memory, etc., as computer-readable media for the program according to the present invention have been disclosed above, the invention is not limited to these examples. Portable recording media such as CD-ROMs can be used as other computer-readable media. In addition, carrier waves can be used as a medium for providing the data of the program according to the present invention via a communication line. [Explanation of Symbols]

[0107] 100 Image Forming Systems 1. Inkjet recording device (droplet ejection device) 12 Image forming unit 121 Inkjet head (droplet ejection head) C Carriage 13 Detection unit 131a light source 131b Light receiving section 14. Cleaning Department 15 Control Unit (Determination Unit) 18 Operation reception section 2. Coating device 22 Coating area P recording medium P1 Recording surface P2 Conveyor surface

Claims

1. An image forming unit that forms an image by ejecting droplets onto the recording surface of a recording medium coated with a pretreatment agent to prevent droplet penetration, A detection unit that detects the density of the transport surface of the recording medium, which has an image formed on it by the image forming unit, on the surface opposite to the recording surface, A determination unit that determines whether the pretreatment agent has been properly applied to the recording surface based on the concentration of the transport surface detected by the detection unit, A droplet dispensing device equipped with the following features.

2. The droplet ejection device according to claim 1, further comprising an application unit provided upstream of the image forming unit in the transport direction for applying the pretreatment agent to the recording surface of the recording medium.

3. The coating unit applies a pretreatment agent by discharge from a nozzle. The droplet dispensing device according to claim 2, wherein the determination unit determines whether or not there is a nozzle defect in the coating portion.

4. The image forming unit comprises a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted. The droplet dispensing device according to any one of claims 1 to 3, wherein the image forming unit scans the carriage in a width direction perpendicular to the transport direction of the recording medium to form an image.

5. The image forming unit forms a color band image by ejecting droplets from the droplet ejection head at the widthwise end of the image forming area of ​​the recording medium during image formation. The droplet dispensing device according to claim 4, wherein the detection unit detects the density of the color band image on the transport surface side.

6. The droplet ejection device according to claim 5, wherein the detection unit has a length greater than or equal to the length of the image scanned and printed by the carriage.

7. The image forming unit comprises a droplet ejection head that ejects droplets from a nozzle, and a carriage on which the droplet ejection head is mounted. The droplet dispensing device according to any one of claims 1 to 3, wherein the image forming unit fixes the carriage to form an image.

8. The image forming unit ejects droplets from the droplet ejection head before the recording operation starts to form a color band image. The droplet dispensing device according to claim 7, wherein the detection unit detects the density of the color band image on the transport surface side.

9. The droplet ejection device according to claim 8, wherein the detection unit is provided below the extension of the transport direction of the image forming unit such that the length of the detection unit in the width direction perpendicular to the transport direction of the recording medium is the same as the length of the image forming area of ​​the recording medium in the width direction.

10. The droplet dispensing device according to any one of claims 1 to 3, wherein the determination unit determines that a coating defect of the pretreatment agent has occurred if the concentration of the transport surface detected by the detection unit is above a predetermined threshold.

11. The droplet dispensing device according to claim 10, further comprising an operation reception unit capable of arbitrarily setting the threshold.

12. The droplet dispensing device according to claim 10, wherein the threshold value is different for each type of recording medium.

13. The droplet dispensing device according to claim 10, further comprising a control unit that interrupts image formation and notifies the user of a warning when the determination unit determines that a pretreatment agent application defect has occurred.

14. A cleaning unit for cleaning the discharge surfaces of the image forming unit and the coating unit, A droplet dispensing device according to claim 10, which references claim 3, further comprising: a control unit that interrupts image formation and causes the cleaning unit to clean the dispensing surface of the coating unit when the determination unit determines that a coating defect has occurred in the pretreatment agent.

15. A droplet dispensing device according to any one of claims 1 to 3, wherein the recording medium is a cloth.

16. The detection unit comprises a light source that irradiates light onto the transport surface of the recording medium, and a light receiving unit that receives the reflected light irradiated by the light source and reflected off the transport surface. A droplet dispensing device according to any one of claims 1 to 3, wherein the concentration of the transport surface is detected from the intensity of the reflected light received by the light receiving unit.

17. A computer for a droplet ejection device comprising: an image forming unit that ejects droplets to form an image on the recording surface of a recording medium coated with a pretreatment agent to prevent droplet penetration; and a detection unit that detects the density of the transport surface on the opposite side of the recording medium from the recording surface during transport of the recording medium on which the image has been formed by the image forming unit, A program that functions as a determination unit to determine whether the pretreatment agent has been properly applied to the recording surface based on the concentration of the transport surface detected by the detection unit.

18. A droplet dispensing device according to claim 1, An image forming system comprising: a coating apparatus having a coating unit for applying a pretreatment agent to the recording surface of a recording medium.

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