Coating device, and printing device equipped with coating device

Abstract

To provide a coating applicator which improves the uniformity of coating of processing liquid to a sheet medium and prevents the deterioration of quality of a coating surface in conveyance of the sheet medium after coating.SOLUTION: A coating applicator comprises: a first rotator which applies processing liquid to a sheet medium; a second rotator which conveys the sheet medium applied with the processing liquid by the first rotator to the downstream; a first medium sensor which detects the sheet medium applied with the processing liquid by the first rotator; and control means which controls the rotational speed of the first rotator according to the detection result of the first medium sensor. The control means calculates a correction value that corrects the rotational speed of the first rotator on the basis of a conveyance interval to the first rotator of the sheet medium detected by the first medium sensor, and corrects the rotational speed in the non-contact time in which the sheet medium is not in contact with the first rotator.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an application device and a printing device including the application device. [Background technology]

[0002] A printing apparatus that forms an image on a sheet-fed medium as a recording medium using liquid ink is known, and an application apparatus that applies a treatment liquid having an effect of aggregating the liquid ink to the sheet-fed medium before printing is also known.

[0003] The coating device applies the treatment liquid to the printing surface of the sheet-fed media by applying the treatment liquid to a roller that comes into contact with the sheet-fed media being conveyed. In order to prevent the treatment liquid from adhering to unintended surfaces in the coating device, a technique is known that stops the rotation of the coating roller when no sheet-fed media is present at the position where the treatment liquid is applied by the coating roller (see Patent Document 1). Summary of the Invention [Problem to be solved by the invention]

[0004] According to the technology of Patent Document 1, the rotation speed of the application roller fluctuates while applying the treatment liquid, and therefore the transport speed of the sheet-fed media fluctuates while the treatment liquid is being applied. If the rotation speed of the application roller fluctuates relative to the transport speed of the sheet-fed media, uneven application of the treatment liquid occurs. In addition, if the rotation speed of the application roller fluctuates while the application roller and the sheet-fed media are in contact, the application roller may rub against the sheet-fed media, damaging the printing surface.

[0005] The present invention has an object to provide a coating device that improves the uniformity of coating of treatment liquid on a sheet of media and prevents deterioration of the quality of the coated surface when the sheet of media is transported after coating. [Means for solving the problem]

[0006] In order to achieve the above object, the present invention relates to a coating device, comprising: a first rotating body that applies a treatment liquid to a sheet of media; a second rotating body that transports the sheet of media coated with the treatment liquid by the first rotating body downstream; a first media sensor that detects the sheet of media coated with the treatment liquid by the first rotating body; and a control means that controls the rotation speed of the first rotating body in response to the detection result of the first media sensor. a downstream media sensor located downstream of the second rotating body and detecting the single media conveyed by the second rotating body; The control means comprises: based on the conveying speed of the single media detected by the first media sensor and the conveying speed of the single media detected by the downstream media sensor, The rotation speed is corrected during a non-contact period when the single media is not in contact with the first rotating body. Effect of the Invention

[0007] According to the present invention, the uniformity of application of treatment liquid to a single medium is improved, and deterioration of the quality of the coated surface is prevented when the single medium is transported after coating. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic explanatory diagram illustrating an example of a printer as an embodiment of a printing device according to the present invention. [Diagram 2] FIG. 2 is a configuration diagram showing a main structure of a coating unit as an embodiment of a coating device according to the present invention. [Diagram 3] FIG. 11 is an explanatory diagram of an operation example of a coating unit as a comparative example. [Figure 4] FIG. 11 is an explanatory diagram of an operation example of a coating unit as a comparative example. [Diagram 5] 5A to 5C are explanatory views of an example of an operation of the application unit according to the first embodiment. [Figure 6] FIG. 2 is a block diagram showing the configuration of a control system of the coating unit according to the first embodiment. [Figure 7] FIG. 4 is a diagram showing an example of a data table used by the application unit according to the first embodiment. [Figure 8] 8A to 8C are explanatory views of another example of the operation of the application unit according to the first embodiment. [Figure 9] 5 is a flowchart showing an example of an operation flow of a coating unit according to the first embodiment. [Figure 10]10A to 10C are explanatory views of an example of the operation of a modified example of the coating unit according to the first embodiment. [Figure 11] 13A to 13C are explanatory views of an example of an operation of a coating unit according to a second embodiment. [Figure 12] 10 is a flowchart showing an example of an operation flow of a coating unit according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of a coating device and a printing device including a coating device according to the present invention will be described with reference to the drawings. Fig. 1 is a diagram showing the overall configuration of a printer 1000 as an embodiment of a printing device. Note that the printer 1000 is an inkjet type printer. The printer 1000 will be described with reference to Fig. 1.

[0010] [Overall configuration of Printer 1000] 1 shows an example of a sheet-type recording medium, and illustrates an inkjet printer 1000 that forms an image by ejecting liquid ink onto a sheet P as a sheet-type medium. The printer 1000 includes an input section 100, a coating section 500 as a coating device, an image forming section 200, a drying section 300, and an output section 400.

[0011] The carry-in section 100 includes a sheet carry-in tray 101 that holds a plurality of sheets P as sheet-fed media used in printing processing, and a feeding device 102 that separates and sends out the sheets P one by one from the sheet carry-in tray 101. The feeding device 102 may have any configuration, such as a device using rollers or a device using air suction, as long as it has the function of separating and transporting the sheets P. The sheets P sent out from the sheet carry-in tray 101 by the feeding device 102 are sent out to a coating section 500 that serves as a coating device.

[0012] The coating section 500 includes a plurality of conveying roller pairs 501 and a coating unit 600 as a coating device. The sheet P sent from the feeding device 102 is conveyed to the coating unit 600 by the plurality of conveying roller pairs 501. In the coating unit 600, the treatment liquid 17 is applied to the sheet P. The sheet P coated with the treatment liquid 17 is sent to the image forming section 200 by the plurality of conveying roller pairs 501.

[0013] The coating unit 600 corresponds to an embodiment of the coating device according to the present invention. The coating section 500 includes a liquid supply unit 700 that supplies the treatment liquid 17 to the coating unit 600, a motor 502 that drives a plurality of conveying roller pairs 501, and a conveying path for the sheet P that is formed by arranging the plurality of conveying roller pairs 501.

[0014] The image forming section 200 includes a pair of registration rollers 201, a sheet conveying device 202, a liquid discharge section 205, and transfer drums 206 and 207. After the sheet P sent out from the coating section 500 arrives, the pair of registration rollers 201 is driven at a predetermined timing to send the sheet P to the sheet conveying device 202.

[0015] The sheet conveying device 202 includes a drum 203 that rotates while supporting the sheet P on its peripheral surface, and a suction device 204 that generates a suction force on the peripheral surface of the drum 203. With this configuration, the sheet conveying device 202 conveys the sheet P while adsorbing it to the peripheral surface of the drum 203, and causes it to pass through a liquid discharge unit 205.

[0016] Further, a transfer cylinder 206 is provided upstream of the drum 203, which receives the sheet P sent from the registration roller pair 201 and transfers the sheet P between the drum 203 and the transfer cylinder 206. A transfer cylinder 207 is provided downstream of the drum 203, which transfers the sheet P conveyed by the drum 203 to the drying section 300.

[0017] The sheet P from the pair of registration rollers 201 is sent to a transfer drum 206 at a predetermined timing, and its leading edge is gripped by a gripping means (gripper) provided on the transfer drum 206. The transfer drum 206 gripping the sheet P rotates to transport the sheet P, and delivers the sheet P to the drum 203 at a position opposite the drum 203.

[0018] A gripping means (gripper) is also provided on the surface of the drum 203, which receives the sheet P gripped and transported by the transfer drum 206 from the transfer drum 206 and grips the sheet P. A plurality of suction holes are formed in a dispersed manner on the surface of the drum 203, and a suction device 204 generates a suction airflow that flows inward from required suction holes of the drum 203. The leading edge of the sheet P transferred from the transfer drum 206 to the drum 203 is gripped by the gripper, and is adsorbed and supported on the drum 203 by the suction airflow of the suction device, and is transported as the drum 203 rotates.

[0019] The liquid discharge section 205 includes discharge units 208 configured to discharge and apply liquids of different colors to the sheet P carried and transported by the drum 203. The discharge units 208 include, for example, a discharge unit 208a that discharges black (K) liquid. The discharge units 208 also include a discharge unit 208b that discharges cyan (C) liquid. The discharge units 208 also include a discharge unit 208c that discharges magenta (M) liquid. And the discharge units 208 also include a discharge unit 208d that discharges yellow (Y) liquid.

[0020] The discharge unit 208 further includes a discharge unit 208e and a discharge unit 208f used for discharging any of YMCK, or special liquid such as white, gold (silver), etc. In addition to the above, a discharge unit for discharging a treatment liquid such as a surface coating liquid may be further provided.

[0021] The ejection unit 208 is, for example, a full-line type head configured with a plurality of liquid ejection heads (hereinafter simply referred to as "heads") each having a nozzle row in which a plurality of nozzles are arranged.

[0022] Each of the discharge units 208 constituting the liquid discharge section 205 performs a discharge operation in response to a drive signal corresponding to printing information used in the printing process. When the sheet P supported on the drum 203 passes through an area facing the liquid discharge section 205, the discharge unit 208 discharges liquid of each color from the discharge unit 208. By this discharge operation, an image corresponding to the printing information is printed on the sheet P.

[0023] The sheet P that has been printed by the liquid ejection unit 205 has liquid applied to it. The sheet P to which the liquid has been applied is sent from the surface of the drum 203 to the transfer drum 207. A gripping means (gripper) for gripping the leading edge of the sheet P is also provided on the surface of the transfer drum 207, and the leading edge of the sheet P is transferred from the gripper of the drum 203 to the gripper of the transfer drum 207, thereby transferring the sheet P from the surface of the drum 203 to the transfer drum 207. Then, the sheet P is sent to the drying unit 300 via the circumferential surface of the transfer drum 207 as the transfer drum 207 rotates.

[0024] The drying section 300 includes a suction conveying mechanism section 301 that conveys the sheet P delivered from the transfer drum 207 of the image forming section 200 under suction, and a drying mechanism section 302 that dries the liquid on the sheet P conveyed by the suction conveying mechanism section 301.

[0025] The discharge section 400 includes a discharge tray 401 on which a plurality of sheets P are stacked. The sheets P conveyed from the drying section 300 are sequentially stacked and held on the discharge tray 401.

[0026] [First embodiment of coating device] Next, a coating unit 600 as a first embodiment of the coating device according to the present invention will be described. As shown in FIG. 2, the coating unit 600 has a transfer roller 1, a coating roller 4 as a first rotating body, a metering roller 50, and a pumping roller 8.

[0027] The transfer roller 1 is rotatably supported at one end of a TR arm 2. A TR spring 3 is connected to the other end of the TR arm 2. A rotation shaft 5 that serves as a fulcrum when the TR arm 2 rotates is disposed at the middle position of the TR arm 2. The transfer roller 1 is biased in a direction to be pressed against the application roller 4 by the rotation of the TR arm 2 about the rotation shaft 5 due to the tensile force of the TR spring 3.

[0028] A TR cam 6 is in contact with the TR arm 2. When the TR cam 6 rotates, a force acts on the transfer roller 1 in a direction resisting the tensile force of the TR spring 3. This force allows the transfer roller 1 to move in a direction away from the application roller 4. The rotational movement of the TR cam 6 is performed by driving a motor 7.

[0029] The application roller 4 and the metering roller 50 are in elastic pressure contact with the draw-up roller 8. The draw-up roller 8 is rotatably supported by a side plate of the application unit 600. The draw-up roller 8 is supported with respect to the side plate of the application unit 600 in a direction in which it comes into contact with or is separated from the transfer roller 1.

[0030] The pumping roller 8 is rotatably supported on a side plate of the supply liquid chamber 9. The supply liquid chamber 9 is swingably supported on a fulcrum 13. An arm 10 is provided on the side plate of the supply liquid chamber 9. The arm 10 is biased by a compression spring 12 via a pin 11. The bias of the compression spring 12 presses the pumping roller 8 against the metering roller 50. The bias of the compression spring 12 also presses the pumping roller 8 against the metering roller 50, so that the metering roller 50 is elastically pressed against the applying roller 4.

[0031] A cam 14 is in contact with the pin 11. The force with which the cam 14 presses the pin 11 changes as the cam 14 rotates. The nip load between the application roller 4 and the metering roller 50 and the nip load between the metering roller 50 and the pumping roller 8 can be changed by the correlation between the force with which the cam 14 presses the pin 11 and the biasing force of the compression spring 12. The rotational operation of the cam 14 is performed by driving a motor 15.

[0032] The transfer roller 1, the application roller 4, the metering roller 50, and the pumping roller 8 are connected by gears and are configured to be rotated by a motor 16. Note that the transfer roller 1, the application roller 4, the metering roller 50, and the pumping roller 8 can also be rotated by contact with each other through elastic pressure contact.

[0033] The supply liquid chamber 9 contains a treatment liquid 17. The pumping roller 8 is immersed in the treatment liquid 17. Therefore, as the pumping roller 8 rotates, the treatment liquid 17 adheres to the outer peripheral surface of the pumping roller 8 and is pumped up. A liquid level sensor 18 for detecting the level of the treatment liquid 17 is attached to the supply liquid chamber 9. The output of the liquid level sensor 18 is monitored by the control means, so that the position at which the pumping roller 8 is immersed in the treatment liquid 17 can be adjusted.

[0034] When the application operation of applying the treatment liquid 17 to the sheet P is performed, the treatment liquid 17 is consumed, and the liquid level of the treatment liquid 17 stored in the liquid supply chamber 9 decreases. Then, when the liquid level of the treatment liquid 17 detected by the liquid level sensor 18 falls below a predefined threshold value, the supply valve 19 is opened and the supply pump 20 is driven. When the supply pump 20 is driven, the treatment liquid 17 stored in the supply tank 21 can be sent to the liquid supply chamber 9. This replenishes the treatment liquid 17 consumed by the application operation of the application roller 4. Then, when the predetermined liquid level is reached, the supply valve 19 is closed and the supply pump 20 is stopped. This allows the liquid level of the treatment liquid 17 stored in the liquid supply chamber 9 to be kept constant.

[0035] The treatment liquid 17 is a liquid that exerts an effect of agglomerating the liquid ink by being applied to the printing surface of the sheet P before the printing process, and may deteriorate over time, such as increasing in viscosity depending on the time it is stored. It is not preferable to use deteriorated treatment liquid 17 for the application operation. Therefore, treatment liquid 17 that has reached a state where it is assumed that a certain amount of aging has occurred is discharged from the supply liquid chamber 9. A drain valve 22, a drain pump 23, and a waste liquid tank 24 are provided as a discharge mechanism. When the drain valve 22 is opened and the drain pump 23 is driven, the treatment liquid 17 stored in the supply liquid chamber 9 can be discharged to the waste liquid tank 24.

[0036] The coating unit 600 having the above configuration draws up the treatment liquid 17 stored in the supply liquid chamber 9 by the rotation of the draw-up roller 8. The drawn-up treatment liquid 17 is carried to the contact position between the draw-up roller 8 and the metering roller 50. Then, by passing through the contact position (nip portion) between the draw-up roller 8 and the metering roller 50, the amount of treatment liquid 17 is adjusted and transferred to the surface of the metering roller 50.

[0037] The treatment liquid 17 transferred to the surface of the metering roller 50 is carried to the contact position (nip portion) with the application roller 4. Then, by passing through the contact position (nip portion) between the metering roller 50 and the application roller 4, the treatment liquid 17 is thinned and transferred to the surface of the application roller 4.

[0038] The thin film of treatment liquid 17 formed on application roller 4 is then carried to the contact position (nip portion) with transfer roller 1 and comes into contact with sheet P. Treatment liquid 17 is applied to the printing surface of sheet P.

[0039] Here, the amount of treatment liquid 17 applied to sheet P varies depending on the rotation speed of application roller 4. That is, the faster the rotation speed of application roller 4, the greater the amount of treatment liquid 17 applied to sheet P. Therefore, if the rotation speed of application roller 4 changes midway through the application of each sheet P, the amount of treatment liquid 17 applied becomes uneven. In other words, if fluctuations in the rotation speed of application roller 4 occur midway through the application operation to each sheet P, this will degrade the image quality obtained by the printing process.

[0040] Furthermore, even if the rotation speed of the application roller 4 is constant, the transport speed of the sheet P relative to the application roller 4 may change. In that case, the amount of treatment liquid 17 applied will also be non-uniform. One factor that may cause a change in the relative transport speed of the sheet P relative to the application roller 4 is the difference in the type of sheet P. In general, the relative transport speed of the sheet P relative to the application roller 4 varies depending on the type of sheet P.

[0041] For example, in the case of sheet P into which treatment liquid 17 does not easily penetrate, such as offset coated paper, a liquid film forms between sheet P and application roller 4, which reduces the coefficient of friction between the outer circumferential surface of application roller 4 and the application surface of sheet P, making it easier for sheet P to slip against application roller 4. In addition, in the case of sheet P into which treatment liquid 17 easily penetrates, such as plain paper, treatment liquid 17 is quickly absorbed into the paper layer, so no liquid film forms and sheet P is less likely to slip. Therefore, the application unit 600 is configured so that the speed of sheet P passing over application roller 4 can be adjusted according to the type of sheet P.

[0042] 2, upstream of the application roller 4 in the conveying direction of the sheet P, an upstream conveying roller pair 25 is provided as a third rotating body that feeds the sheet P into the contact portion between the application roller 4 and the transfer roller 1. A guide plate pair 26 is provided on a path from the upstream conveying roller pair 25 to the application roller 4 and the transfer roller 1. The sheet P that has passed through a plurality of conveying roller pairs 501 of the application section 500 passes through the upstream conveying roller pair 25 and the guide plate pair 26, and is conveyed to the contact portion between the application roller 4 and the transfer roller 1. Then, the treatment liquid 17 is applied to the sheet P when it passes between the contact portion between the application roller 4 and the transfer roller 1.

[0043] On the downstream side of the application roller 4, there are provided a downstream transport roller pair 27 as a second rotating body for transporting the sheet P immediately after the treatment liquid 17 has been applied, and a guide member 28 for guiding the sheet P to the downstream transport roller pair 27. The downstream transport roller pair 27 and the upstream transport roller pair 25 are configured to be driven by a motor 30 separate from the application roller 4. In other words, the application roller 4 is driven by the motor 16, but the downstream transport roller pair 27 and the upstream transport roller pair 25 are driven by the motor 30. Therefore, the rotation speed of the application roller 4 and the rotation speeds of the downstream transport roller pair 27 and the upstream transport roller pair 25 can be independently adjusted by a control means.

[0044] In addition, the downstream transport roller pair 27 is configured with rollers having glass beads adhered to their surfaces. By using these rollers, it is possible to suppress rubbing of the surface to which the treatment liquid 17 is applied, which occurs when the downstream transport roller pair 27 and the sheet P slip. As a result, it is possible to suppress uneven rubbing. It is also possible to suppress uneven application caused by the treatment liquid 17 adhering to the surface of the downstream transport roller pair 27.

[0045] The sheet P that has passed through the downstream-side transport roller pair 27 is delivered to a plurality of transport roller pairs 501 of the coating section 500 and transported downstream, as shown in FIG.

[0046] Returning to FIG. 2, a first media sensor 29 serving as a first sensor for detecting the leading or trailing end of a sheet P transported by the rotation of the applying roller 4 and the transfer roller 1 is disposed downstream of the applying roller 4, facing the transport path of the sheet P. The first media sensor 29 is a timing sensor for detecting the transport timing of each of the multiple sheets P. A control unit 800 serving as a control means, which will be described later, corrects the rotation speed of the motor 16 that rotates the applying roller 4, depending on the timing at which the first media sensor 29 detects the sheet P. That is, the control unit 800 corrects the rotation speed of the applying roller 4 based on the detection result of the first media sensor 29.

[0047] In the following, a case where the first media sensor 29 is a timing sensor will be described as an example. However, the first media sensor 29 is not limited to a timing sensor. For example, it may be a speed sensor that detects the conveying speed of the sheet P. That is, when a plurality of sheets P are conveyed continuously, the conveying speed of the sheet P may be detected based on the time difference between the timing at which the first media sensor 29 detects the leading edge of the preceding sheet P and the timing at which the leading edge of the succeeding sheet P is detected (the conveying interval of the sheet P). In this case, the control unit 800 corrects the rotation speed of the application roller 4 based on the sheet conveying speed detected by the first media sensor 29.

[0048] By correcting the rotation speed of the motor 16, the conveying speed of the sheet P relative to the application roller 4 can be adjusted to be constant during the application operation. Also, the amount of treatment liquid 17 applied to the sheet P, which is affected by the rotation speed of the motor 16, can be made uniform. Also, the relative conveying speed of the sheet P, which is easily affected by the surface properties of the sheet P and therefore fluctuates, can be adjusted to match the rotation speed of the downstream conveying roller pair 27.

[0049] [Explanation of Comparative Example] If it were impossible to adjust the rotation speed of the applying roller 4 to match the rotation speed of the downstream conveying roller pair 27 based on the timing of conveying the sheet P immediately after the applying roller 4 has applied the treatment liquid 17, the conveying speed at the contact portion between the applying roller 4 and the transfer roller 1 would become unstable. Here, a phenomenon that occurs when the conveying speed becomes unstable will be described.

[0050] As shown in FIG. 3, when the conveying speed of the sheet P at the contact portion between the application roller 4 and the transfer roller 1 becomes slower than the conveying speed of the sheet P at the nip portion of the downstream conveying roller pair 27, a speed difference occurs in the sheet P between the contact portion between the application roller 4 and the transfer roller 1 and the nip portion of the downstream conveying roller pair 27. As a result, tension that tries to pull the sheet P in relatively opposite directions is applied to the sheet P at each nip portion. When tension is applied to the sheet P, slippage and rubbing occur especially between the downstream conveying roller pair 27 and the sheet P. As a result, a phenomenon occurs in which the treatment liquid 17 applied by the application roller 4 is peeled off by the downstream conveying roller pair 27, and the treatment liquid 17 is applied unevenly to the sheet P. As a result, the quality of the image obtained by the printing process on the sheet P is reduced.

[0051] 4, a case is assumed in which the conveying speed of the sheet P at the contact portion between the application roller 4 and the transfer roller 1 is faster than the conveying speed of the sheet P at the nip portion of the downstream conveying roller pair 27. In this case, the sheet P sags between the contact portion between the application roller 4 and the transfer roller 1 and the nip portion of the downstream conveying roller pair 27. If the sheet P sags, the sheet P may get stuck in the guide member 28 and cause a jam.

[0052] For the reasons described above, the coating unit 600 according to this embodiment controls the rotation speed of the motor 16 so that the conveying speed of the sheet P at the contact portion between the coating roller 4 and the transfer roller 1 matches the conveying speed of the sheet P at the nip portion of the downstream conveying roller pair 27. That is, the coating unit 600 corrects the conveying speed of the sheet P at the nip portion of the coating roller 4 in accordance with the conveying speed of the sheet P at the nip portion of the downstream conveying roller pair 27. To this end, when the control unit corrects the rotation speed of the motor 16, the conveying speed of the sheet P at the nip portion of the coating roller 4 is set to be equal to or higher than the conveying speed of the sheet P at the nip portion of the downstream conveying roller pair 27.

[0053] When the conveying speed of the sheet P in the nip portion of the applying roller 4 is increased, the sheet P becomes slack between the applying roller 4 and the downstream conveying roller pair 27 as shown in Fig. 5. Giving the sheet P slack results in adjustment in a direction that does not generate tension. In this way, even if the correction accuracy of the rotation speed of the applying roller 4 is not precise, it is possible to prevent rubbing between the sheet P and the downstream conveying roller pair 27. The slack of the sheet P is set to a level that does not cause a jam.

[0054] As described above, the coating unit 600 prevents rubbing of the surface to which the treatment liquid 17 is applied by adjusting the conveying speed at the contact portion between the coating roller 4 and the transfer roller 1 so as to be equal to or faster than the conveying speed of the sheet P at the downstream conveying roller pair 27 so as to convey the sheet P. Also, by adjusting the conveying speed difference so as not to generate tension in the sheet P between the coating roller 4 and the downstream conveying roller pair 27, stable conveying can be performed while maintaining the state of the coated surface. The adjusted conveying speed difference is set to a level that does not cause the sheet P to sag too much and jam.

[0055] [Control configuration of coating unit 600] Next, a control unit 800 provided in the coating section 500 will be described as a control unit for controlling the operation of the coating unit 600. As shown in Fig. 6, the control unit 800 is configured to link an operation section 801, a storage section 802, a sensor information section 803, a motor speed correction section 804, a coating roller driving section 805, and a conveying roller driving section 806.

[0056] The control unit 800 includes a CPU that executes a predetermined control program, a ROM that stores the control program, and a RAM that functions as a work area for the CPU's arithmetic processing. The control unit 800 executes the control program to control the operation of each of the other units. In other words, the control unit 800 comprehensively controls the overall operation of the application unit 500.

[0057] The operation unit 801 receives input from an input interface such as a touch panel arranged on the outer surface or top surface of the housing of the coating unit 500, and passes the input to the control unit 800. The operation unit 801 also has a function of displaying the processing results of the control unit 800 and a function of notifying the operating state of the coating unit 500, and functions as a notifying means. Through the operation unit 801, the control unit 800 can set sheet characteristic information as characteristic information indicating the characteristics of the sheet P, such as the brand, basis weight, or thickness of the sheet P.

[0058] The function equivalent to the operation unit 801 may be realized by an operation panel provided in the printer 1000. In that case, the sheet property information is set by the operation panel provided in the printer 1000, and the information is notified to the control unit 800. The above information may also be set via an operation screen of a print instruction terminal (for example, a computer) connected to the printer 1000. The set sheet property information of the sheet P is transmitted from the operation unit 801 to the control unit 800.

[0059] The application roller driving unit 805 controls the driving of the motor 16 so as to rotate at a predetermined rotation speed based on a command from the control unit 800. The conveying roller driving unit 806 controls the driving of the motors 30 and 502 so as to rotate at a predetermined rotation speed based on a command from the control unit 800.

[0060] The storage unit 802 stores speed correction values ​​for each sheet characteristic information as table data, which are classified according to a plurality of pieces of sheet characteristic information. The speed correction value is information in which an initial value of correction data for correcting the rotation speed of the motor 16 is associated with each piece of sheet characteristic information. FIG. 7 shows an example of a correction table 807 as table data stored in the storage unit 802. The correction table 807 stores data for setting and adjusting an initial value of the conveying speed of the sheet P by the application roller 4 for sheet characteristic information configured for each combination of brands A to C of the sheet P and the corresponding basis weights or thicknesses a to c. The initial value of the conveying speed is set taking into consideration the tendency of the conveying speed to vary depending on the characteristics of the sheet P.

[0061] The correction data is data (motor correction data V1 to V12) for adjusting the rotation speed of the motor 16 to keep the speed difference with the downstream conveying roller pair 27 constant even if the relative conveying speed between the applying roller 4 and the sheet P fluctuates. When the characteristic information of the sheet P corresponding to the correction table 807 shown in FIG. 7 is not stored, the user can additionally set and store it via the operation unit 801. The correction data stored in the correction table 807 is, for example, a data setting for increasing the rotation speed of the motor 16 so as to increase the conveying speed by the applying roller 4 in the case of coated paper that is prone to slippage between the applying roller 4 and the sheet P. Also, for plain paper that is unlikely to slippage, the data setting is a data setting for decreasing the rotation speed of the motor 16 so as to decrease the conveying speed by the applying roller 4.

[0062] Further, the sensor information unit 803 constantly receives sensor information output from various sensors such as the first media sensor 29. Information detected by the output of the various sensors is transmitted to the control unit 800. The control unit 800 is configured to be able to determine whether or not the sheet P is in contact with the contact portion between the application roller 4 and the transfer roller 1 based on the information transmitted from the sensor information unit 803. Furthermore, the control unit 800 reads correction data stored in the storage unit 802 based on the sensor information from the sensor information unit 803, controls the motor speed correction unit 804, and performs motor speed correction. Note that the correction of the motor speed is performed during the "non-contact time" when the sheet P is not in contact with the application roller 4.

[0063] The motor speed correction unit 804 executes a process to determine whether the arrival timing of the sheet P at the first media sensor 29 is a specified value. Then, the motor speed correction unit 804 transmits the determination result to the control unit 800. If the determination process of the motor speed correction unit 804 determines that the arrival timing of the sheet P is the specified value, the control unit 800 controls the application operation to continue without changing the speed correction value. Furthermore, if the determination process of the motor speed correction unit 804 determines that the arrival timing of the sheet P is out of the specified value, the control unit 800 calculates a change value for the correction data. Then, the control unit 800 uses the calculated change value to update the corresponding values ​​of the motor correction data V1 to V12 stored in the correction table 807 using the change value.

[0064] In this embodiment, the control unit 800 temporarily stops the sheet P at the upstream conveying roller pair 25 provided upstream of the application roller 4, and corrects the conveying speed of the application roller 4 based on the time from when the conveyance of the sheet P is resumed until the first media sensor 29 detects the sheet P, i.e., the time until the sheet P reaches the first media sensor 29.

[0065] The motor correction data V1 to V12 in the correction table 807 stored in the storage unit 802 have their set values ​​updated according to the timing at which the sheet P reaches the first media sensor 29. In this embodiment, the rotation speed of the application roller 4 is controlled according to the arrival timing, but similar control can be performed by using a sensor that detects the conveying speed of the sheet P.

[0066] The process of updating the correction data for correcting the rotation speed of the motor 16 using the correction table 807 is performed, for example, by performing test printing to check the operation of the discharge unit 208 before the liquid discharge unit 205 in the image forming unit 200 starts printing processing. For example, the test printing is used to check whether the liquid discharge head provided in the discharge unit 208 is not discharging properly and to check the print quality. When performing this test printing, an operation of applying the treatment liquid 17 to the sheet P is performed. During this operation, the timing at which the sheet P conveyed to the application roller 4 reaches the first media sensor 29 is detected, and an update value for the motor correction data V1 to V12 stored in the correction table 807 is calculated based on the arrival timing and characteristic information of the sheet P.

[0067] Then, after the test printing, the motor correction data V1 to V12 is updated during the time when the sheet P is transported to the application roller 4 during the execution of the actual printing. That is, the control unit 800 updates the motor correction data V1 to V12 at the timing when the sheet P is not in contact with the application roller 4. By controlling in this way, the sheet P is transported at the corrected rotation speed of the motor 16 during the application of the treatment liquid 17 to the first sheet P of the print job related to the actual printing. By using the above-mentioned method, when a new print job is executed using the updated correction data in the same print job or in the same operating environment, the application operation can be executed under the corrected conditions from the beginning. This makes it possible to obtain a more stable quality of the coated surface.

[0068] Furthermore, the motor speed correction unit 804 writes correction data to the data stored in the storage unit 802 when the sheet P is not present at the contact portion between the application roller 4 and the transfer roller 1. Furthermore, the motor speed correction unit 804 executes the speed correction of the motor 16 when the sheet P is not present at the contact portion between the application roller 4 and the transfer roller 1.

[0069] The timing of correcting the rotation speed will be described with reference to FIG. 8. As shown in FIG. 8, after the preceding sheet P passes through the contact portion between the application roller 4 and the transfer roller 1, the correction process is performed from when the first media sensor 29 detects the rear end Pr of the sheet P until the leading end Pf of the next sheet P reaches the contact portion between the application roller 4 and the transfer roller 1. Then, while the sheet P is passing through the contact portion between the application roller 4 and the transfer roller 1, the rotation speed of the motor 16 is maintained constant. That is, while the application roller 4 is applying the treatment liquid 17 to the sheet P, the rotation speed of the application roller 4 is maintained constant. The period during which the sheet P is passing through the contact portion between the application roller 4 and the transfer roller 1 corresponds to the period during which the first media sensor 29 is detecting the sheet P.

[0070] If the rotation speed of the motor 16 is changed when the sheet P is present at the contact area between the application roller 4 and the transfer roller 1, the amount of treatment liquid 17 applied to the sheet P will vary during the course of the sheet P, adversely affecting the quality of application of the treatment liquid 17 to the sheet P. Even if the rotation speed of the motor 16 is adjusted when the sheet P is not in contact with the application roller 4, and the number of rotations of the application roller 4 varies, this does not affect the uneven application. Therefore, the reason for adjusting the rotation speed of the motor 16 at the above timing is to prevent uneven application. If uneven application of the treatment liquid 17 to the printing surface of the sheet P occurs, differences will occur in the coagulation state of the ink discharged by the liquid discharge unit 205, degrading the image quality, but the application unit 600 can prevent the degradation of image quality.

[0071] [Control process of coating unit 600] Next, an example of control in the coating process executed by the coating unit 600 according to this embodiment will be described with reference to the flowchart in Fig. 9. First, the user sets characteristic information including the brand, basis weight, thickness, etc. of the sheet P via the operation unit 801 (S901). The set characteristic information of the sheet P is transmitted from the operation unit 801 to the control unit 800.

[0072] Next, the control unit 800 reads data corresponding to the characteristic information from the correction data stored in the storage unit 802 (S902). More specifically, the motor correction data associated with the characteristic information stored in the correction table 807 shown in FIG. 7 is read into the RAM.

[0073] Next, in S903, the control unit 800 determines whether or not the first media sensor 29 detects the sheet P (S903). The output of the first media sensor 29 is constantly captured by the sensor information unit 803. Therefore, the control unit 800 can determine whether or not the sheet P is in a position to contact the applying roller 4 by inquiring of the output state of the first media sensor 29 from the sensor information unit 803. Here, if the first media sensor 29 detects the sheet P (S903: NO), the rotation speed of the motor 16 is not adjusted, and the process loops.

[0074] If the first media sensor 29 has not detected the sheet P (S903: YES), the control unit 800 executes a process of writing the correction data read from the storage unit 802 to the motor speed correction unit 804 (S904). Next, the motor speed correction unit 804 executes a control process of changing the rotation speed of the motor 16 (S905).

[0075] Next, it is determined whether the timing at which the sheet P, which is conveyed while being coated with the treatment liquid 17 by the coating roller 4, reaches the first media sensor 29 is a specified value (S906). The timing determined in S906 means the time from when the conveyance of the sheet P is temporarily stopped by the upstream conveyance roller pair 25 arranged upstream of the coating roller 4 and then resumed until the sheet P reaches the first media sensor 29. That is, in S906, the timing at which the sheet P reaches the first media sensor 29 is determined by determining whether the time from when the sheet P is detected by the first media sensor 29 after the conveyance is resumed after a temporary stop until it is within a specified time as a preset threshold value. In S906, when it is determined that the elapsed time until the first media sensor 29 detects the sheet P is within the specified time (S906: YES), it is determined whether it is time to end the operation of the coating unit 600. Here, if it is time to end the operation of the coating unit 600, the process is ended (S909: YES). On the other hand, if it is not time to end the operation of the coating unit 600, the process returns to S902 (S909: NO).

[0076] When it is determined in S906 that the arrival time is not within the specified time (S906: NO), the motor speed correction unit 804 calculates a change value of the correction data based on the detected arrival timing (S907). After the change value of the correction data is calculated, the control unit 800 updates the correction value of the correction data stored in the storage unit 802 based on the change value from the motor speed correction unit 804 (S908). Thereafter, the control unit 800 returns the process to S902.

[0077] In the above description, the control unit 800 temporarily stops the transport of the sheet P by the upstream transport roller pair 25 provided upstream of the applying roller 4, and changes the control parameters of the motor 16 based on the time until the first media sensor 29 detects the sheet P after the transport is resumed. However, this embodiment is not limited to this, and a second media sensor 40 may be provided as a second sensor upstream of the applying roller 4, as shown in FIG.

[0078] 10, when the second media sensor 40 is provided, the first media sensor 29 and the second media sensor 40 may be used together to detect the sheet P. In this case, the sensor information output from the first media sensor 29 and the second media sensor 40 is also taken into the sensor information unit 803.

[0079] In addition, in the configuration shown in Figure 8, when multiple sheets P are transported continuously, the interval between when the first media sensor 29 detects the previous sheet P and when the first media sensor 29 subsequently detects the next sheet P may be determined by comparing it with a specified time.

[0080] As described above, the coating unit 600 according to the first embodiment measures the transport speed of the sheet P that is transported while being coated with the treatment liquid 17 by the coating roller 4, or the passing timing of the sheet P past the coating roller 4. Based on the measurement value, a correction value for adjusting the transport speed of the coating roller 4 is calculated.

[0081] Then, in the gap between the timing of the passage of the previous sheet P and the timing of the subsequent passage of the subsequent sheet P, i.e., while the sheet P is not in contact with the applying roller 4, the conveying speed of the applying roller 4 is corrected using the correction value. Since the conveying speed of the applying roller 4 is corrected as described above, the rotational speed of the applying roller 4 is maintained constant while the treatment liquid 17 is being applied to the sheet P. Since the rotational speed of the applying roller 4 affects the amount of treatment liquid 17 applied to the sheet P, a constant rotational speed can provide stable application performance.

[0082] Furthermore, according to the coating unit 600 according to the first embodiment, the difference in rotation speed between the coating roller 4 and the pair of downstream transport rollers 27 can be corrected by updating the correction value. By correcting this difference in rotation speed, the tension applied to the sheet P between the coating roller 4 and the pair of downstream transport rollers 27 can be adjusted. By adjusting this tension, it is possible to prevent the sheet P from slipping at the pair of downstream transport rollers 27.

[0083] Therefore, according to the coating unit 600 of the first embodiment, the sheet P after the treatment liquid 17 is applied thereto can be prevented from slipping due to the conveying means, and deterioration in the quality of the coated surface after coating can be prevented. That is, the treatment liquid 17 can be applied evenly from the leading edge to the trailing edge of the sheet P without unevenness, and further, a phenomenon that deteriorates the quality of the coated surface during the conveyance of the coated sheet P can be prevented. Furthermore, since there is no need to use a large-scale configuration such as a conveying drum, the above effects can be achieved with an inexpensive and compact configuration.

[0084] Furthermore, according to the coating unit 600 according to the first embodiment, when correcting the speed of the coating roller 4, the rotation speed of the coating roller 4 is adjusted so that the conveying speed by the coating roller 4 is faster than the conveying speed by the downstream conveying roller pair 27. This prevents the sheet P from being taut between the coating roller 4 and the downstream conveying roller pair 27. As a result, the same effect as above can be obtained without precise correction of the rotation speed of the coating roller 4.

[0085] Moreover, according to the coating unit 600 of the first embodiment, a speed correction value for correcting the rotation speed of the coating roller 4 is held in advance in table data as a suitable initial value determined for each type of sheet P. Then, a correction value is calculated based on information indicating the conveying status detected by a plurality of sensors while performing the coating process by the coating roller 4, for the initial value stored in the table data. This allows the correction value to be small and a large speed change to be suppressed, enabling a more stable coating operation. That is, according to the coating unit 600 of the first embodiment, it is assumed that an excessive supply of the treatment liquid 17 is performed to the coating roller 4 when the speed difference for correction is increased, but such an excessive supply of the treatment liquid 17 can be prevented.

[0086] In addition, the downstream transport roller pair 27 of the coating unit 600 according to the first embodiment uses rollers with glass beads attached to their surfaces, which makes it difficult for the treatment liquid 17 to adhere to the rollers, thereby suppressing the occurrence of slippage. As a result, more stable coating quality can be obtained.

[0087] [Second embodiment of coating device] Next, a coating unit 600a as a second embodiment of the coating device according to the present invention will be described. As shown in Fig. 11, the coating unit 600a has a third media sensor 45 disposed downstream of the downstream transport roller pair 27 as a downstream media sensor, in addition to the first media sensor 29. The coating unit 600a can calculate the transport speed of the sheet P toward the third media sensor 45 by using the timing at which the third media sensor 45 detects the sheet P. Therefore, the transport speed of the sheet P relative to the first media sensor 29 can be adjusted to match the transport speed of the sheet P relative to the third media sensor 45. This makes it possible to obtain more stable coating performance.

[0088] [Control process of coating unit 600a] Next, an example of control in the coating process performed by the coating unit 600a will be described with reference to the flowchart of FIG. 12. The control configuration of the coating unit 600a is the same as that of the first embodiment. Therefore, detailed description of the control configuration will be omitted, and the same reference numerals will be used for the reference numerals of the control blocks linked to the control unit 800 in the following description. Also, since S1201 to S1205 in FIG. 12 are the same processes as S901 to S905 already described, detailed description will be omitted.

[0089] After the motor speed correction unit 804 executes a control process to change the rotation speed of the motor 16 (S1205), the first media sensor 29 disposed downstream of the application roller 4 measures a first arrival time t1 as the arrival time of the sheet P (S1209). Then, the third media sensor 45 disposed downstream of the downstream conveying roller pair 27 measures a second arrival time t2 as the arrival time of the sheet P (S1210).

[0090] Thereafter, it is determined whether the deviation amount of the first arrival time t1 from the second arrival time t2 is within a specified value (S1211). In S1211, when it is determined that the deviation amount is within the specified value (S1211: YES), if it is time to end the operation of the coating unit 600a, the process is ended (S1214: YES), and if it is not time to end the operation of the coating unit 600a, the process returns to S1203 (S1214: NO).

[0091] In S1211, when it is determined that the deviation amount is not within the specified value (S1211: NO), the motor speed correction unit 804 calculates a change value of the correction data based on the detected arrival timing (S1212). After the change value of the correction data is calculated, the control unit 800 updates the correction value of the correction data stored in the storage unit 802 based on the change value from the motor speed correction unit 804 (S1213). Thereafter, the control unit 800 returns the process to S1202.

[0092] As described above, the coating unit 600a according to the second embodiment includes the first media sensor 29 downstream of the coating roller 4, and the third media sensor 45 downstream of the downstream transport roller pair 27. Based on the detection of these multiple sensors, the speed of the coating roller 4 can be corrected in accordance with the transport speed of the sheet P by the downstream transport roller pair 27 from the sheet P on which the treatment liquid 17 has been applied by the coating roller 4 until the next sheet P reaches the coating roller 4. This makes it possible to maintain a constant rotation of the coating roller 4 while the treatment liquid 17 is being applied to the sheet P, i.e., while the sheet P is in contact with the coating roller 4. The rotation speed of the coating roller 4 affects the amount of treatment liquid 17 applied to the sheet P, so if the rotation speed is constant, stable coating performance can be obtained.

[0093] Furthermore, according to the coating unit 600a according to the second embodiment, the speed difference between the coating roller 4 and the pair of downstream transport rollers 27 can be corrected. As a result, the tension applied to the sheet P between the coating roller 4 and the pair of downstream transport rollers 27 can be adjusted. This tension adjustment can prevent the sheet P from slipping at the pair of downstream transport rollers 27. Furthermore, by correcting the rotation speed of the coating roller 4 while also measuring the transport speed by the pair of downstream transport rollers 27, more effective correction can be made.

[0094] In the coating unit 600 according to the first embodiment and the coating unit 600a according to the second embodiment, the downstream transport roller pair 27 and the upstream transport roller pair 25 serving as rotating bodies are exemplified as transport means for transporting the sheet P to the coating roller 4. However, in this embodiment, it is not necessary to limit these transport means to rotating bodies, and they may be realized by transport belts.

[0095] In the above description, the first embodiment shown in Fig. 2, the modified example of the first embodiment shown in Fig. 10, the continuous paper feeding example of the first embodiment shown in Fig. 2, and the second embodiment shown in Fig. 11 are each implemented separately. However, the coating device according to the present invention may be configured by combining these multiple embodiments and modified examples. [Explanation of symbols]

[0096] 4: Application roller 16: Motor 17: Processing liquid 25: Upstream conveying roller pair 27: downstream conveying roller pair 29: First media sensor 30: Motor 40: Second media sensor 45: Third media sensor 102:Feeding device 200: Image forming unit 201: Registration roller pair 202: Sheet conveying device 208: Discharge unit 300:Drying section 501: Transport roller pair 502: Motor 600, 600a: Coating unit 800: Control unit 801:Operation unit 802: Storage section 803: Sensor information section 804: Motor speed correction unit 805: Application roller drive unit 806: Transport roller drive unit 807: Correction table 1000: Printer P: Seat t1: First arrival time t2 :Second arrival time [Prior art documents] [Patent documents]

[0097] [Patent Document 1] JP 2009-220002 A

Claims

1. A first rotating body that applies a treatment liquid to a sheet of media; a second rotating body that conveys downstream the sheet of media onto which the treatment liquid has been applied by the first rotating body; a first media sensor that detects a sheet of media onto which the treatment liquid has been applied by the first rotating body; a control means for controlling a rotation speed of the first rotating body in response to a detection result of the first media sensor; a downstream media sensor located downstream of the second rotating body and detecting the single media conveyed by the second rotating body; Equipped with The control means correcting the rotation speed during a non-contact time when the single medium is not in contact with the first rotating body based on a transport speed of the single medium detected by the first media sensor and a transport speed of the single medium detected by the downstream media sensor; A coating device comprising:

2. A first rotating body that applies a treatment liquid to a sheet of media; a second rotating body that conveys downstream the sheet of media onto which the treatment liquid has been applied by the first rotating body; a first media sensor that detects a sheet of media onto which the treatment liquid has been applied by the first rotating body; a control means for controlling a rotation speed of the first rotating body in response to a detection result of the first media sensor, The control means correcting the rotation speed so that a transport speed of the single medium by the first rotating body is equal to or higher than a transport speed of the single medium by the second rotating body during a non-contact time when the single medium is not in contact with the first rotating body; A coating device comprising:

3. A first rotating body that applies a treatment liquid to a sheet of media; a second rotating body that conveys downstream the sheet of media onto which the treatment liquid has been applied by the first rotating body; a first media sensor that detects a sheet of media onto which the treatment liquid has been applied by the first rotating body; a control means for controlling a rotation speed of the first rotating body in response to a detection result of the first media sensor; a storage unit that stores table data that stores an initial value of a speed correction value that corrects the rotation speed of the first rotating body corresponding to each characteristic information, by distinguishing the characteristics of the single medium according to characteristic information that indicates the characteristics of the single medium; The control means correcting the rotational speed during a non-contact time when the single medium is not in contact with the first rotating body by referring to the table data; A coating device comprising:

4. A first rotating body that applies a treatment liquid to a sheet of media; a second rotating body that conveys downstream the sheet of media onto which the treatment liquid has been applied by the first rotating body; a first media sensor that detects a sheet of media onto which the treatment liquid has been applied by the first rotating body; a control means for controlling a rotation speed of the first rotating body in response to a detection result of the first media sensor, The control means a correction value for correcting a rotational speed of the first rotating body is calculated based on a transport interval of the single medium to the first rotating body detected by the first media sensor, and the rotational speed is corrected based on the correction value during a non-contact time when the single medium is not in contact with the first rotating body. A coating device comprising:

5. the first media sensor is a timing sensor that detects a timing of transport of the sheet of media; The coating device according to claim 1 .

6. the first media sensor is a speed sensor that detects a transport speed of the sheet of media; The coating device according to claim 1 .

7. the control means corrects the rotational speed of the first rotating body based on a time from when the first media sensor detects the single medium to when the first media sensor detects the next single medium being transported toward the first rotating body. The coating device according to any one of claims 1 to 6.

8. The second rotating body has glass beads on its surface. The coating device according to any one of claims 1 to 7.

9. an image forming unit that forms an image on a sheet of media on which a treatment liquid has been applied; an application unit that applies the treatment liquid to the sheet of media, The coating unit is the coating device according to any one of claims 1 to 8. A printing device comprising:

Images