Coating apparatus and image forming system

Abstract

To make it hard to cause a trouble that a coating liquid stuck to a coating roller is fixed.SOLUTION: A liquid level detection sensor 58 (liquid level detection means) is provided for detecting that the liquid level of the coating liquid G stored in the storage part 57 is lower than a non-supply position where the coating liquid G cannot be supplied to the coating roller 52. Then, after the power source 40 of the apparatus is turned off, the discharge of the coating liquid G from the reservoir 57 by the coating liquid discharger 63, 76, 116 is started, and the liquid level detection sensor 58 detects that the liquid level of the coating liquid G remaining in the reservoir 57 has reached the non-supply position, the coating roller 52 and the pressure roller 66 are rotated in contact with each other by the contact-separation mechanism 71 for the predetermined time Tx.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a coating device that applies a coating liquid to a substrate such as a sheet, and an image forming system that includes the coating device and an image forming device. [Background technology]

[0002] BACKGROUND ART Conventionally, in an image forming system in which an image forming apparatus such as an inkjet printer is installed, a coating device that applies a coating liquid to a coating target such as a sheet is installed (see, for example, Patent Document 1).

[0003] More specifically, in Patent Document 1, an applicator (liquid applicator) is installed upstream of an image forming apparatus (inkjet printer) and applies a coating liquid (treatment liquid) such as a bleeding suppressant to the surface of a sheet conveyed to the inkjet printer, thereby making it difficult for image defects such as bleeding to occur in the image formed on the sheet by the image forming apparatus. In Patent Document 1, the coating device is equipped with a storage section (supply pan) in which the coating liquid is stored, a pumping roller that pumps up the coating liquid stored in the storage section, an application roller that applies the coating liquid pumped up by the pumping member to a sheet, and a pressure roller (transfer roller) that clamps and transports the sheet together with the application roller. The coating device is also equipped with a contact / separation means for contacting and separating the pressure roller with respect to the coating roller, a sensor for detecting the liquid level of the coating liquid stored in the storage section, a coating liquid supply means for supplying the coating liquid to the storage section, and a coating liquid discharge means for discharging the coating liquid from the storage section. Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional coating devices, even when the power is turned off and the coating liquid is discharged from the reservoir by the coating liquid discharge means, the coating liquid remaining on the coating roller can sometimes become stuck to the coating roller. If the coating liquid becomes stuck to the coating roller in this way, when the coating liquid is subsequently applied to a sheet by the coating roller, the amount of coating liquid applied to the sheet can vary, and the quality of the image formed on the sheet can be reduced.

[0005] The present invention has been made to solve the above-mentioned problems, and aims to provide an application device and an image forming system that are less likely to experience the problem of application liquid adhering to the application roller solidifying. [Means for solving the problem]

[0006] The coating device of this invention comprises a storage section in which coating liquid is stored, a coating roller that applies the coating liquid supplied indirectly or directly from the storage section to a sheet, a pressure roller that contacts the coating roller to form a nip and can clamp and transport the sheet together with the coating roller, a contact / separation means for moving the pressure roller toward and away from the coating roller, a coating liquid supply means for supplying the coating liquid to the storage section, a coating liquid discharge means for discharging the coating liquid from the storage section, and a liquid level detection means for detecting that the liquid level of the coating liquid stored in the storage section has fallen below a non-supply position where it cannot be supplied to the coating roller.After the power to the device is turned off and the coating liquid discharge means starts to discharge the coating liquid from the storage section, and the liquid level detection means detects that the liquid level of the coating liquid remaining in the storage section has reached the non-supply position, the contact / separation means rotates the coating roller and the pressure roller in contact with each other for a predetermined time. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide an application device and an image forming system that are less likely to experience problems such as the application liquid adhering to the application roller becoming solidified. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is an overall view showing an image forming system according to an embodiment of the present invention; [Figure 2] FIG. 1 is a configuration diagram showing a main part of an image forming apparatus. [Figure 3] 3 is a schematic diagram showing a supply path and a discharge path of a coating liquid to a storage section in the coating device. FIG. [Figure 4] FIG. 2 is a configuration diagram showing a main part of a coating device. [Figure 5] 10A and 10B are diagrams illustrating the operation of the main parts of the coating device when the power is turned on. [Figure 6] 10A and 10B are diagrams illustrating the operation of the main parts of the coating device when the power is off. [Figure 7] 1A is a schematic diagram of a pressure roller and an application roller when they are left in a depressurized state, and FIG. 1B is a schematic diagram of a pressure roller and an application roller when they are left in a pressurized state. [Figure 8] 10 is a flowchart showing an example of control performed in the coating device. [Figure 9] 10A and 10B are diagrams illustrating an operation of a coating apparatus when the power supply is turned off, according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In each drawing, the same or corresponding parts are designated by the same reference numerals, and redundant explanations will be appropriately simplified or omitted.

[0010] First, the overall configuration and operation of an image forming system 100 will be described with reference to FIG. In FIG. 1, 1 denotes an inkjet printer as an image forming apparatus, 50 denotes an application device that applies a coating liquid as a pretreatment to a sheet P transported to the image forming apparatus 1, 80 denotes a paper feeding device that feeds a sheet P such as paper, 85 denotes a drying device that dries the ink on the sheet P after image formation, and 90 denotes a paper discharge device on which the sheet P discharged from the drying device 85 is stacked. As shown in FIG. 1, an image forming system 100 in this embodiment is configured such that, from the upstream side, a paper feeder 80, a coating device 50, an image forming apparatus 1, a drying device 85, and a paper discharge device 90 are connected.

[0011] The operation of the image forming system 100 will be briefly described with reference to FIG. First, when a print command together with image information is input from a personal computer or the like to the control unit of the image forming system 100, a sheet P is fed from a paper feed cassette 81 by a paper feed roller 82. The sheet P fed from the paper feed cassette 81 is then conveyed by a conveyance roller toward the coating device 50 via a first conveyance path K1. In this embodiment, the paper feed device 80 is configured to feed cut paper stored in the paper feed cassette 81, but the paper feed device 80 can also be configured to feed roll paper.

[0012] Thereafter, the sheet P as a coating target transported to the coating device 50 is transported to the coating device main section 51 via the second transport path K2. Then, in the coating device main section 51, a coating liquid (pretreatment liquid) for suppressing bleeding, show-through, etc. is applied to the lower surface of the sheet P (the sheet surface that becomes the front surface during image formation) (this is the coating process). Thereafter, the sheet P coated with the coating liquid is transported to the reversal path K4 (fourth transport path), where the transport direction is reversed and the sheet P is transported to the image forming device 1 via the third transport path in an inverted state (the sheet surface on which the coating liquid has been applied becomes the front surface (upper surface)). Here, when a mode (double-sided print mode) in which images are formed on both sides of the sheet P is selected in the image forming apparatus 1, it is necessary to apply the coating liquid to both sides of the sheet P, so the sheet P after the coating liquid has been applied to one side is transported to the inversion path K4, the transport direction is reversed and the sheet is inverted, then transported to the double-sided path K5 (fifth transport path) and transported again to the coating device main section 51. Then, the sheet P after the coating liquid has been applied to the other side in the coating device main section 51 is transported to the image forming apparatus 1 as is via the third transport path K3. The configuration and operation of the coating device main section 51 in the coating device 50 will be described in detail later with reference to FIGS.

[0013] Thereafter, the sheet P transported to the image forming apparatus 1 passes through a sixth transport path K6, and then is transported to the transport drum 2, where a desired image is formed on the front surface (upper surface) of the sheet P. At this time, the front surface of the sheet P has been coated with a coating liquid as a pre-treatment, which prevents bleeding of the image, show-through, and the like. Then, the sheet P on which the image has been formed is transported to the drying device 85 via the seventh transport path K7. The configuration and operation of the image forming apparatus 1 will be described in detail later with reference to FIG.

[0014] Thereafter, the sheet P transported to the drying device 85 passes through an eighth transport path K8 and is then transported to the dryer section 86, where the image on the sheet P is dried. Then, the sheet P with the dried image is transported to the paper discharge device 90 via a ninth transport path K9. Here, when the above-described double-sided print mode is selected, images need to be formed on both sides of the sheet P, so the sheet P after the image on one side has been dried is transported to a reversing path K10 (tenth transport path), where the transport direction is reversed and the sheet is inverted, and then transported to double-sided paths K11 and K12 (eleventh and twelfth transport paths) and transported again to the transport drum 2 of the image forming apparatus 1. Then, on the transport drum 2, the sheet P, on which the desired image has also been formed on the other side, is transported again to the drying device 85 via the seventh transport path K7. Then, the sheet P, on which the image on the other side has been dried in the dryer unit 86, is transported directly to the paper discharge device 90 via the ninth transport path K9.

[0015] Thereafter, the sheet P conveyed to the sheet discharging device 90 passes through a thirteenth conveying path K13 and is then stacked on the sheet discharging tray 91. In this way, a series of operations in the image forming system 100 is completed.

[0016] The image forming apparatus 1 (inkjet printer) will be described in detail below with reference to FIG. In Figure 2, 2 indicates a conveying drum that conveys sheet P, 5 indicates a clipper that grips sheet P on the conveying drum 2, 6 indicates a separating member that separates sheet P from the conveying drum 2, and 7 indicates a conveying belt that conveys sheet P separated from the conveying drum 2. 10Y, 10M, 10C, 10K, 10S1, and 10S2 denote heads (printing modules) in which image forming units for printing and imaging by an inkjet method are unitized, and 30 denotes a base frame for holding beam members 35 and the like.

[0017] 2, the image forming apparatus 1 in this embodiment is for forming color images and is provided with a black head 10K, three color (yellow, magenta, cyan) heads 10Y, 10M, and 10C, and two coating (special color) heads 10S1 and 10S2. These six heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 are radially aligned in the direction of rotation of the conveyor drum 2, facing each other with small gaps between them. The six heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 have almost the same structure except for the color (type) of ink used for printing. Each of the heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 is a roughly rectangular parallelepiped unit whose main portion is made up of a piezoelectric actuator, and which is provided with nozzles that eject ink as a liquid (droplets), an ink tank filled with ink, a control board (control unit), and the like.

[0018] The operation of the image forming apparatus 1 will be briefly described with reference to FIG. First, when a sheet P is carried into the image forming apparatus 1, the sheet P is transported by the transport rollers 4 toward the transport drum 2. Meanwhile, the heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 of each color convert the input image information into writing information of each color. The sheet P conveyed to the conveying drum 2 is positioned on the conveying drum 2 while being gripped by the clipper 5, and is conveyed along with the rotation of the conveying drum 2 in the counterclockwise direction. Then, the sheet P is transported in the direction of the arrow in Figure 2 by the rotation of the transport drum 2, and ink as a liquid is sprayed sequentially from the heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 of each color based on the write information, thereby forming a desired image on the sheet P. Thereafter, the sheet P on which the desired image has been formed is separated from the conveying drum 2 by the separating member 6. Then, the sheet P separated from the conveying drum 2 is conveyed by the conveying belt 7, and further conveyed toward the drying device 85 by the conveying rollers.

[0019] Hereinafter, the characteristic coating device 50 in the image forming system 100 of the present embodiment will be described in detail with reference to FIGS. The coating device 50 is a device that applies a coating liquid G to a sheet P as a coating target. As shown in Figure 4, the coating device 50 (main part 51 of the coating device) in this embodiment is composed of a storage section 57 in which the coating liquid G is stored, a coating roller 52, a pumping roller 55, a pressure roller 66, a pressure roller 67, a liquid level detection sensor 58 as a liquid level detection means, pipes 62, 63, etc.

[0020] 3, coating apparatus 50 (coating apparatus main section 51) is provided with reservoir 57, coating liquid tank 75, recycle reservoir 76 (reserve tank), waste liquid tank 77, filter case 79, and the like.

[0021] The reservoir 57 is connected to a coating liquid tank 75 in which new coating liquid G is stored via a supply pipe 62 and a coating liquid supply pipe 84 . When the coating liquid G is supplied to the storage section 57 for the first time, the pump 110 is operated, and the three-way valve 115 is switched so that the coating liquid G in the coating liquid tank 75 is filled into the storage section 57 via the coating liquid supply pipe 84 and the supply pipe 62. Then, when the storage section 57 is filled with the coating liquid G up to a predetermined position, the operation of the pump 110 is stopped, and the supply of the coating liquid G is interrupted. During the printing operation (during the coating process), fresh coating liquid G is supplied from the coating liquid tank 75 to the storage section 57 as needed as the coating liquid G is consumed in the storage section 57. Furthermore, when replacing part or all of the coating liquid G in the storage section 57 with new liquid, fresh coating liquid G is supplied appropriately from the coating liquid tank 75 to the storage section 57 as the coating liquid G is wasted in the storage section 57. In this way, the coating liquid tank 75 , supply pipe 62 , coating liquid supply pipe 84 , pump 110 , and three-way valve 115 function as a coating liquid supplying means for supplying the coating liquid G to the reservoir 57 .

[0022] Furthermore, storage unit 57 is connected to recycle storage unit 76 (reserve tank) via discharge pipe 63. Furthermore, recycle storage unit 76 is connected to storage unit 57 via recycle pipe 102, filter case 79, and supply pipe 62. If the coating process is not performed even after a certain time has elapsed after the printing operation has finished, or if the power supply (main power supply) of the coating device 50 (image forming system 100) is turned off, the solenoid valve 116 opens, and the coating liquid G in the storage section 57 is stored in the recycle storage section 76 via the discharge pipe 63 due to the difference in height. In this way, the recycle storage section 76, the solenoid valve 116, and the discharge pipe 63 function as a coating liquid discharge means that discharges the coating liquid G from the storage section 57. Then, when the next printing operation is started, the pump 110 is operated and the three-way valve 115 is switched so that the coating liquid G in the recycled storage section 76 is supplied to the storage section 57 via the recycled pipe 102, the filter case 79, and the supply pipe 62. The filter case 79 has the function of removing impurities that have become mixed in the coating liquid G to be recycled. In this way, the recycle storage section 76, pump 110, three-way valve 115, recycle pipe 102, filter case 79, and supply pipe 62 function as a coating liquid recycle supply means that supplies the coating liquid G discharged by the coating liquid discharge means and stored in the recycle storage section 76 back to the storage section 57. In addition, when the amount of coating liquid G supplied from the recycle reservoir 76 to the reservoir 57 is insufficient as described above, the shortage is supplied from the coating liquid tank 75 to the reservoir 57 .

[0023] The recycle reservoir 76 is connected to a waste liquid tank 77 via a waste liquid pipe 101 . The coating liquid G is stored in the recycle storage section 76 for a certain period of time, but if the coating process is not performed after the certain period of time has elapsed, the pump 112 is operated to transfer the coating liquid G in the recycle storage section 76 to the waste liquid tank 77 via the waste liquid pipe 101. The reason for carrying out such control is to avoid the inconvenience that the coating liquid G stored in the recycle storage section 76 deteriorates over time and becomes difficult to use as the coating liquid G.

[0024] 4, a certain amount of coating liquid G is stored in a storage section 57 of the coating device 50 (coating device main section 51). The storage section 57 is a box-shaped member having a substantially rectangular parallelepiped shape with its longitudinal direction being perpendicular to the plane of the paper in FIG. The pumping roller 55 as a pumping member is disposed so as to extend in the longitudinal direction (the direction perpendicular to the plane of FIG. 4, which is the direction of the rotation axis). The pumping roller 55 functions as a pumping member that pumps up the coating liquid G stored in the storage section 57. 4, the pumping roller 55 carries the coating liquid G in the storage section 57. The coating liquid G carried by the pumping roller 55 is adjusted to an appropriate amount at the position where the pumping roller 55 abuts on the application roller 52, which rotates counterclockwise in FIG. Then, the coating liquid G carried by the coating roller 52 is applied (coating process) to the sheet surface (lower surface) of the sheet P conveyed to the nip between the coating roller 52 and the pressure roller 66. At this time, the pressure roller 66 rotates in the clockwise direction in FIG. 4 while being pressed by the pressure roller 67 which rotates in the counterclockwise direction in FIG. Although not shown in the drawings, the roller portion of the pumping roller 55 is formed over almost the entire longitudinal area inside the storage section 57. The roller portions of the application roller 52, the pressure roller 66, and the pressure roller 67 are also formed over almost the same longitudinal range. This longitudinal range is a range that includes the longitudinal range of the largest size sheet P that can be passed through.

[0025] The application roller 52, the draw-up roller 55, the pressure roller 66, and the pressure roller 67 are driven by a drive motor 73 via a gear train, and rotate in a predetermined direction. The pressure roller 66 and the pressure roller 67 are formed as a unit, and are configured to be movable together in the vertical direction in Fig. 4 by a contact / separation mechanism 71 (e.g., a cam mechanism) connected to the unit as a contact / separation means. When the application process is performed, the pressure roller 66 is moved by the contact / separation mechanism 71 to the contact position (a position where it contacts the application roller 52) shown in Figs. 4, 5(A), etc. On the other hand, when the application process is not performed, the pressure roller 66 is moved together with the pressure roller 67 by the contact / separation mechanism 71 to the separated position (a position where it is separated from the application roller 52) shown in Fig. 5(B), etc. Furthermore, a plurality of pipes (supply pipe 62 and discharge pipe 63) are connected to the bottom of reservoir 57. These pipes 62 and 63 function as previously described with reference to FIG.

[0026] As described above, in this embodiment, the pumping roller 55 pumps up the coating liquid G stored in the storage section 57 and supplies the coating liquid G directly to the coating roller 52 . The application roller 52 applies the application liquid G, which is indirectly supplied from the reservoir 57 via the pumping roller 55, onto the sheet P. The pressure roller 66 is configured to come into contact with the application roller 52 to form a nip, and to be able to pinch and transport the sheet P together with the application roller 52 . The contact / separation mechanism 71 functions as a contact / separation means for moving the pressure roller 66 relatively toward and away from the application roller 52 .

[0027] 4 to 6, etc., the coating device 50 (coating device main part 51) in this embodiment is provided with a liquid level detection sensor 58 as a liquid level detection means for detecting that the liquid level (water level) of the coating liquid G stored in the storage part 57 has fallen below a non-supply position where the coating liquid G cannot be supplied to the coating roller 52. Specifically, the liquid level detection sensor 58 (liquid level detection means) may be, for example, a reflective photosensor that optically detects whether or not the coating liquid G is present at the "non-supply position." Here, the "non-supply position" is a liquid level position where the draw-up roller 55 does not come into contact with the coating liquid G remaining in the storage section 57. More specifically, when the liquid level of coating liquid G reaches the lower end of pumping roller 55 and coating liquid G cannot be supplied to applying roller 52 via pumping roller 55, the liquid level of coating liquid G stored in reservoir 57 is deemed to have reached the "non-supply position," and this state is detected by liquid level detection sensor 58. Liquid level detection sensor 58 detects the state of having reached the non-supply position based on a change in the electrical signal generated when the liquid level of coating liquid G changes from a state in which it has not yet descended to the non-supply position to a state in which it has descended to the non-supply position.

[0028] 4 to 6, etc., in this embodiment, the power supply 40 of the coating device 50 (which in this embodiment also serves as the main power supply of the image forming system) is turned off, the coating liquid discharge means 63, 76, 116 (see FIG. 3) starts to discharge the coating liquid G from the storage section 57, and the liquid level detection sensor 58 (liquid level detection means) detects that the liquid level of the coating liquid G remaining in the storage section 57 has reached a non-supply position. After this, the contact / separation mechanism 71 (contact / separation means) rotates (idle-spins) the coating roller 52 and the pressure roller 66 in a contacting state for a predetermined time Tx (a first predetermined time, which in this embodiment is about 10 seconds). That is, when the liquid level detection sensor 58 detects that the liquid level of the application liquid G has reached the non-supply position, the application roller 52 and the pressure roller 66 are rotated idly while being in contact with each other by the contact / separation mechanism 71 for a predetermined time Tx (first predetermined time). After the predetermined time Tx (first predetermined time) of idle rotation has ended, the application roller 52 and the pressure roller 66 are separated from each other by the contact / separation mechanism 71 (contact / separation means). In this specification, the "idle rotation" of the application roller 52 and the pressure roller 66 is defined to mean the rotation (rotational drive) of the application roller 52 and the pressure roller 66 without any application process (sheet transport) to the sheet P.

[0029] Specifically, in this embodiment, when the power is on (when the power supply 40 is on), and the coating process is performed on the sheet P (when the sheet is passed), the control unit 70 controls the contact / separation mechanism 71 to lower the pressure unit that holds the pressure roller 66 and the pressure roller 67, so that the pressure roller 66 contacts the coating roller 52 to form a nip, as shown in Fig. 5(A). Then, the drive motor 73 drives the draw-up roller 55, the coating roller 52, the pressure roller 66, and the pressure roller 67 to rotate in the directions of the arrows shown in Fig. 5(A), and the coating liquid G is applied to the sheet P that has been conveyed to the nip between the coating roller 52 and the pressure roller 66. When the power is on and the application process is not being performed on the sheet P (when no paper is passing through), the control unit 70 controls the contact / separation mechanism 71 to raise the pressure unit that holds the pressure roller 66 and the pressure roller 67, and the pressure roller 66 separates from the application roller 52, releasing the nip, as shown in Fig. 5(B). At this time, the drive motor 73 also stops driving each roller, including the application roller 52.

[0030] In this embodiment, when the power supply 40 is turned off, as shown in FIG. 6(A), the control unit 70 opens the electromagnetic valve 116 (see FIG. 3), and the coating liquid G in the storage unit 57 is discharged toward the recycle storage unit 76 via the discharge pipe 63. 6(B), as discharge from discharge pipe 63 progresses, when liquid level detection sensor 58 detects that the liquid level (water level) of coating liquid G in storage section 57 has dropped to the non-supply position, this state is grasped by control section 70, and control section 70 controls contact / separation mechanism 71 to lower the pressure unit holding pressure roller 66 and pressure roller 67, so that pressure roller 66 comes into contact with coating roller 52, forming a nip. Then, driven by drive motor 73, coating roller 52 and pressure roller 66 (and draw-up roller 55 and pressure roller 67) each rotate in the direction of the arrows shown in FIG. 6(B) (they are driven to rotate idly). As a result, the coating liquid G carried on the application roller 52 and pressure roller 66 (and the pumping roller 55 and pressure roller 67) is squeezed out under contact pressure between the rollers, reducing the amount of coating liquid G carried on each roller (particularly the amount of coating liquid G carried on the application roller 52). Then, when such idle driving ends, the control unit 70 controls the contact / separation mechanism 71 to lift the pressure unit that holds the pressure roller 66 and the hold-down roller 67, and the pressure roller 66 separates from the application roller 52, releasing the nip. Also, the drive motor 73 stops driving each roller, including the application roller 52. The operation of the coating device 50 when the power is off may be performed, for example, by power supply from an auxiliary power supply (not shown) installed in the coating device 50 (image forming system 100), or the power supply 40 may be controlled so that it is officially shut off after the above-mentioned operation is completed by operating the power-off switch.

[0031] In this manner, in this embodiment, when the power is turned off and the coating liquid G is being discharged from the storage section 57, if the liquid level detection sensor 58 detects that the liquid level of the coating liquid G in the storage section 57 has dropped to the non-supply position, the coating roller 52 and the pressure roller 66 are driven idly in contact for a predetermined time Tx (first predetermined time), thereby making it less likely that the coating liquid G adhering to the coating roller 52 will solidify. More specifically, if the application roller 52 and the pressure roller 66 are separated from each other while the application liquid G is being discharged from the reservoir 57 when the power is off, or if the application roller 52 and the pressure roller 66 are in contact but not rotating, a relatively large amount of application liquid G remains on the application roller 52, and the applied application liquid G eventually adheres to the application roller 52. If the next application process is carried out on the sheet P while the application liquid G remains adhered to the application roller 52, variations in the amount of application liquid G applied to the sheet P may occur, and the quality of the image formed on the sheet P may be reduced. In contrast to this, in this embodiment, when the power is turned off, the coating liquid G is discharged from the storage section 57, and when the liquid level detection sensor 58 detects that the liquid level of the coating liquid G in the storage section 57 has dropped to the non-supply position (when no new coating liquid G is being supplied to the coating roller 52), the coating roller 52 and the pressure roller 66 are driven idly in a contacting state, so that the coating liquid G adhering to the coating roller 52 is squeezed out (the amount of adhesion is reduced), making it less likely that the coating liquid G will adhere to the coating roller 52.

[0032] Furthermore, in this embodiment, after the idle driving in which the application roller 52 and the pressure roller 66 are in contact with each other when the power is off as described above is completed (after the application liquid G adhering to the application roller 52 is completely squeezed out), the application roller 52 and the pressure roller 66 are put into a non-contact state (separated state), which makes it less likely that the application liquid G will adhere locally to the application roller 52. 7(B), if the application roller 52 and the pressure roller 66 are left in contact (pressurized state) after idle driving with the application roller 52 and the pressure roller 66 in contact with each other while the power is off is completed, some of the application liquid G adhering to the application roller 52 is squeezed out, but the application liquid G adhering to the nip N' tends to solidify, resulting in an uneven application of the application liquid G on the application roller 52. If the next application step is performed on the sheet P in this state, the above-mentioned variations in the amount of application liquid and deterioration of image quality are likely to occur. 7A, in this embodiment, after the idle driving in which the application roller 52 and the pressure roller 66 are in contact with each other when the power is off is completed, the application roller 52 and the pressure roller 66 are left in a non-contact state (separated state), so that the application liquid G that has been adhering to the nip N is less likely to solidify, and the application liquid G is adhered almost uniformly to the application roller 52. Therefore, even when the next application process is performed on the sheet P, the above-mentioned variations in the amount of application liquid and degradation in image quality are less likely to occur.

[0033] Here, in this embodiment, when deterioration of the coating liquid G stored in the storage section 57 is detected by the timer 41 (see Figure 4) as a liquid deterioration detection means, the coating liquid G is supplied to the storage section 57 by the coating liquid supply means 62, 75, 84, 110, 115, and the application roller 52 and the pressure roller 66 are rotated idly while being in contact with each other by the contact and separation mechanism 71 (contact and separation means) for a second predetermined time Tw (predetermined time). Here, the timer 41 functions as a liquid deterioration detection means that detects that the application liquid G stored in the storage section 57 has deteriorated when the time (off period) during which the application device 50 (image forming system 100) is stopped while the power supply 40 is on reaches a first predetermined value (a predetermined value, for example, a predetermined number of days W).

[0034] Specifically, when the application device 50 (image forming system 100) is stopped while the power supply 40 is on, the time since the operation was stopped (the number of days since the off period) is measured by the timer 41. When the time measured by the timer 41 (the number of days since the off period) reaches a predetermined number of days W, it is determined that the application liquid G stored in the storage unit 57 has deteriorated due to being left unused for a long period of time, and new application liquid G is supplied from the application liquid tank 75 to the storage unit 57. Then, in the reservoir 57 to which the new coating liquid G has been supplied, the coating roller 52 and the pressure roller 66 (and the draw-up roller 55 and the presser roller 67) are rotated in a contact state. Then, the coating liquid G that has finally been used (the coating liquid G in the storage section 57) is discharged from the discharge pipe 63. That is, after the idling for the second predetermined time Tw described above has ended, the application roller 52 and the pressure roller 66 are separated from each other by the contact / separation mechanism 71 (contact / separation means), and the coating liquid G is discharged from the storage section 57 by the coating liquid discharge means 63, 76, 116. By performing these operations when the power is turned on, deteriorated coating liquid G adhering to each roller, such as the coating roller 52, is removed even when the power is turned on, and new coating liquid G is carried on, so that the next coating process can be performed satisfactorily. In addition, the deteriorated coating liquid G is discharged from the reservoir 57, so that the effect is further exerted.

[0035] In this embodiment, when the timer 41 (liquid deterioration detection means) detects deterioration of the coating liquid G in the storage section 57 while the power is on, new coating liquid G is supplied from the coating liquid tank 75 to the storage section 57, but recycled coating liquid G may also be supplied from the recycled storage section 76 to the storage section 57. In more detail, when the operation of the application device 50 (image forming system 100) is stopped while the power supply 40 is on and deterioration of the application liquid G stored in the storage section 57 is detected by the timer 41 (see Figure 4) as a liquid deterioration detection means, the application liquid G can be supplied to the storage section 57 by the application liquid recycling supply means 62, 76, 79, 102, 110, 115, which supplies the application liquid G discharged by the application liquid discharge means 63, 76, 116 and stored in the recycling storage section 76 back to the storage section 57, and the application roller 52 and the pressure roller 66 can be rotated idly while being abutted against each other by the contact / separation mechanism 71 (contact / separation means) for a second predetermined time Tw.

[0036] In addition, in this embodiment, the timer 41 as a liquid deterioration detection means is configured to detect that the coating liquid G stored in the storage section 57 has deteriorated when the time during which the power supply 40 is turned on and the operation of the coating device 50 is stopped reaches a first predetermined value (predetermined value). In contrast to this, the timer 41 as a liquid deterioration detection means may be configured to detect that the coating liquid G stored in the storage section 57 has deteriorated when the operating time of the coating device 50 while the power supply 40 is on until the operation of the coating device 50 is stopped reaches a second predetermined value (predetermined value).

[0037] Furthermore, even when the power supply 40 is turned off, just as when the power supply 40 is turned on, when the liquid deterioration detection means detects deterioration of the coating liquid G stored in the storage section 57, the coating liquid G may be supplied to the storage section 57 by the coating liquid supply means 62, 75, 84, 110, 115, and the application roller 52 and the pressure roller 66 may be rotated idly while being in contact with each other by the contact / separation mechanism 71 (contact / separation means) for a second predetermined time Tw.

[0038] An example of the control performed in the coating apparatus 50 described above will be described below with reference to the flowchart of FIG. 8, first, when the power supply 40 is turned on (step S1), it is determined whether the time during which the coating device 50 has been continuously stopped while the power supply is on (the number of days that have passed since the off-period) exceeds W days based on the detection result of the timer 41 (step S2). As a result, if the number of days that have passed since the off-period has not exceeded W days, it is determined that there is no deterioration of the coating liquid G, and the preparation for operation is completed without performing any special operation (step S7). On the other hand, if it is determined in step S2 that the number of days since the off period has elapsed is W days, it is determined that deterioration of the coating liquid G has occurred, and new coating liquid G is filled into the storage unit 57 from the coating liquid tank 75 (step S3). Then, the pressure roller 66 is brought into contact with the application roller 52 by the contact / separation mechanism 71 (step S4), and the drive motor 73 is operated to idle the application roller 52, pressure roller 66, and other rollers (step S5). Then, after such idle rotation has been performed for a second predetermined time Tw, the coating liquid G in the storage unit 57 is discharged from the discharge pipe 63 (step S6), and preparation for operation is completed (step S7). Then, when use of the coating device 50 is finished and the power supply 40 is turned off (switched off) (step S8), discharge of the coating liquid G in the storage section 57 from the discharge pipe 63 begins, and it is determined whether the liquid level detection sensor 58 has turned on (whether the coating liquid G has descended to the non-supply position) (step S9). Then, when the liquid level detection sensor 58 turns on (when the coating liquid G has descended to the non-supply position), the contact / separation mechanism 71 brings the pressure roller 66 into contact with the coating roller 52 (step S10), and the drive motor 73 is operated to idle the coating roller 52, the pressure roller 66, and other rollers (step S11). Then, after such idle rotation has been performed for a predetermined time Tx, the power supply 40 is officially shut off (turned off) (step S13).

[0039] <Modification> As shown in FIG. 9, a coating device 50 (a coating device main section 51) in this modification is configured so that a coating roller 52 can directly draw up the coating liquid G stored in a storage section 57. That is, the coating device 50 in the modified example is not provided with the draw-up roller 55 as in the coating device described with reference to FIGS. In the coating device 50 of the modified example, when the power is turned off and the coating liquid G is being discharged from the storage section 57, if the liquid level detection sensor 58 detects that the liquid level of the coating liquid G in the storage section 57 has dropped to the "non-supply position", the coating roller 52 and the pressure roller 66 are driven idly in a contact state for a predetermined time Tx. However, in this case, the "non-supply position" is a liquid surface position where the applying roller 52 does not come into contact with the application liquid G remaining in the reservoir 57. In the coating device 50 configured in this manner, the coating liquid G adhered to the coating roller 52 is less likely to solidify.

[0040] As described above, the coating device 50 (image forming system 100) in this embodiment is provided with: a storage section 57 in which coating liquid G is stored; a coating roller 52 that applies the coating liquid G, supplied indirectly or directly from the storage section 57, to the sheet P; and a pressure roller 66 that contacts the coating roller 52 to form a nip and can pinch and transport the sheet P together with the coating roller 52. The coating device 50 is also provided with a contact / separation mechanism 71 (contact / separation means) that moves the pressure roller 66 toward and away from the coating roller 52; coating liquid supply means 62, 75, 84, 110, 115 that supply the coating liquid G to the storage section 57; coating liquid discharge means 63, 76, 116 that discharge the coating liquid G from the storage section 57; and a liquid level detection sensor 58 (liquid level detection means) that detects when the liquid level of the coating liquid G stored in the storage section 57 falls below a non-supply position where the coating liquid cannot be supplied to the coating roller 52. Then, the power supply 40 of the device is turned off, the coating liquid discharge means 63, 76, 116 starts discharging the coating liquid G from the storage section 57, and after the liquid level detection sensor 58 detects that the liquid level of the coating liquid G remaining in the storage section 57 has reached the non-supply position, the contact / separation mechanism 71 rotates the coating roller 52 and the pressure roller 66 in a contacting state for a predetermined time Tx. This makes it less likely that the coating liquid G adhering to the coating roller 52 will solidify.

[0041] In this embodiment, one or more rollers that relay the coating liquid G may be interposed between the pumping roller 55 and the applying roller 52. In this case, the pumping roller 55 pumps up the coating liquid G stored in the storage section 57 and indirectly supplies it to the applying roller 52. In addition, in this embodiment, a separation mechanism 71 that moves the pressure roller 66 is used as the separation means, but a separation mechanism that moves the application roller 52 can also be used, or a separation mechanism that moves the pressure roller 66 and the application roller 52 separately can also be used. In this embodiment, a current plate can be installed between the drawing-up roller 55 and the bottom of the reservoir 57 . Furthermore, in this embodiment, the present invention is applied to the coating device 50 as a pretreatment device for the inkjet printer 1, but the application of the present invention is not limited to this, and the present invention can be applied to any coating device that stores a coating liquid. Even in these cases, the same effects as those of this embodiment can be obtained.

[0042] It is clear that the present invention is not limited to the present embodiment, and that within the scope of the technical concept of the present invention, the present embodiment may be modified as appropriate in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and the number, position, shape, etc. of the components may be any number, position, shape, etc. that is suitable for implementing the present invention.

[0043] 1. Image forming device (inkjet printer), 40 power supply, 41 Timer (liquid deterioration detection means), 50 coating equipment, 51 Coating device main part, 52 application roller (application member), 55 pumping roller (pumping member), 57 reservoir (feed pan), 58 liquid level detection sensor (liquid level detection means), 62 supply pipe, 63 Discharge pipe (coating liquid discharge means), 66 pressure roller (pressure member), 75 coating liquid tank, 76 Recycle storage section, 77 Waste tank, 79 filter case, 84 coating liquid supply pipe (coating liquid supply means), 100 Image forming system, 101 waste pipe, 102 recycling pipe (coating liquid recycling supply means), G: Coating liquid (liquid), P: Sheet (subject to be coated).

[0044] The present invention can also be embodied in a combination of Supplementary Notes 1 to 8, as follows. (Appendix 1) a storage section in which the coating liquid is stored; an application roller that applies the application liquid supplied indirectly or directly from the storage unit onto a sheet; a pressure roller that contacts the application roller to form a nip and is capable of nipping and conveying a sheet together with the application roller; a contact / separation means for relatively contacting and separating the pressure roller with respect to the application roller; a coating liquid supply means for supplying a coating liquid to the storage section; a coating liquid discharge means for discharging the coating liquid from the reservoir; a liquid level detection means for detecting that the liquid level of the coating liquid stored in the storage section has fallen below a non-supply position where the coating liquid cannot be supplied to the coating roller; Equipped with a coating device characterized in that, after the power supply to the device is turned off and the coating liquid discharge means starts discharging the coating liquid from the storage section, and the liquid level detection means detects that the liquid level of the coating liquid remaining in the storage section has reached the non-supply position, the contact and separation means rotates the coating roller and the pressure roller in a contacted state for a predetermined time. (Appendix 2) 2. The coating device according to claim 1, wherein the application roller and the pressure roller are separated by the separation means after the predetermined period of idling has ended. (Appendix 3) a pumping roller that pumps up the coating liquid stored in the storage section and supplies the coating liquid to the coating roller directly or indirectly; The coating device according to claim 1 or 2, wherein the non-supply position is a liquid level position where the draw-up roller does not come into contact with the coating liquid remaining in the storage section. (Appendix 4) the application roller is configured to be able to directly draw up the application liquid stored in the storage section, The coating device according to claim 1 or 2, wherein the non-supply position is a liquid level position where the coating roller does not come into contact with the coating liquid remaining in the storage section. (Appendix 5) 5. The coating device according to claim 1, wherein when deterioration of the coating liquid stored in the storage section is detected by the liquid deterioration detection means, the coating liquid is supplied to the storage section by the coating liquid supply means or by a coating liquid recycle supply means that supplies the coating liquid discharged by the coating liquid discharge means and stored in the recycle storage section back to the storage section, and the application roller and the pressure roller are rotated idly in a contacting state by the contact and separation means for a second predetermined time. (Appendix 6) The coating device according to claim 5, wherein the liquid deterioration detection means detects that the coating liquid stored in the storage section has deteriorated when the time during which the device is stopped while the power is on reaches a first predetermined value, or when the operating time of the device until the device is stopped while the power is on reaches a second predetermined value. (Appendix 7) 7. The coating device according to claim 5, wherein after the second predetermined time of idling has ended, the application roller and the pressure roller are separated by the contact / separation means, and the coating liquid is discharged from the storage section by the coating liquid discharge means. (Appendix 8) An image forming system comprising: the coating device according to any one of Supplementary Notes 1 to 7; and an image forming apparatus. [Prior art documents] [Patent documents]

[0045] [Patent Document 1] Japanese Patent Publication No. 2023-174173

Claims

1. a storage section in which the coating liquid is stored; an application roller that applies the application liquid supplied indirectly or directly from the storage unit onto a sheet; a pressure roller that contacts the application roller to form a nip and is capable of nipping and conveying a sheet together with the application roller; a contact / separation means for relatively contacting and separating the pressure roller with respect to the application roller; a coating liquid supply means for supplying a coating liquid to the storage section; a coating liquid discharge means for discharging the coating liquid from the reservoir; a liquid level detection means for detecting that the liquid level of the coating liquid stored in the storage section has fallen below a non-supply position where the coating liquid cannot be supplied to the coating roller; Equipped with a coating device characterized in that, after the power supply to the device is turned off and the coating liquid discharge means starts discharging the coating liquid from the storage section, and the liquid level detection means detects that the liquid level of the coating liquid remaining in the storage section has reached the non-supply position, the contact and separation means rotates the coating roller and the pressure roller in a contacted state for a predetermined time.

2. 2. The coating device according to claim 1, wherein the application roller and the pressure roller are separated from each other by the separation means after the predetermined period of idling has ended.

3. a pumping roller that pumps up the coating liquid stored in the storage section and supplies the coating liquid to the coating roller directly or indirectly; 3. The coating device according to claim 1, wherein the non-supply position is a liquid level position where the draw-up roller does not come into contact with the coating liquid remaining in the storage section.

4. the application roller is configured to be able to directly draw up the application liquid stored in the storage section, 3. The coating device according to claim 1, wherein the non-supply position is a liquid level position where the coating roller does not come into contact with the coating liquid remaining in the reservoir.

5. 3. The coating device according to claim 1, wherein when deterioration of the coating liquid stored in the storage section is detected by the liquid deterioration detection means, the coating liquid is supplied to the storage section by the coating liquid supply means or by a coating liquid recycle supply means that supplies the coating liquid discharged by the coating liquid discharge means and stored in the recycle storage section back to the storage section, and the coating roller and the pressure roller are rotated idly in a contacting state by the contact and separation means for a second predetermined time.

6. The coating device according to claim 5, characterized in that the liquid deterioration detection means detects that the coating liquid stored in the storage section has deteriorated when the time during which the device is stopped while the power is on reaches a first predetermined value, or when the operating time of the device until the device is stopped while the power is on reaches a second predetermined value.

7. The coating device according to claim 5, characterized in that after the second predetermined time of idling has ended, the application roller and the pressure roller are separated by the contact / separation means, and the coating liquid is discharged from the storage section by the coating liquid discharge means.

8. 3. An image forming system comprising: the coating device according to claim 1; and an image forming device.

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