Apparatus for coating treatment solution and image forming apparatus

Abstract

The present invention provides a processing agent coating apparatus and an image forming apparatus that can suppress the occurrence of banding-like uneven coating on a recording medium caused by the processing agent and improve the uniformity of the processing agent coating. [Solution] A processing agent liquid coating device mounted on an image forming apparatus, comprising: a coating roller for coating a conveyed recording medium; a pressure roller for applying pressure to the coating roller; a supply roller for supplying the processing agent to the coating roller; and a first control unit that rotates the coating roller for a predetermined rotation time between the time job information is acquired by the image forming apparatus and the time the recording medium reaches the coating roller.

Description

Technical Field

[0001] The present invention relates to a treatment liquid application device and an image forming apparatus.

Background Art

[0002] In an image generation apparatus that performs imaging printing on a medium by inkjet, a technique for improving image quality by applying a treatment agent to the medium in the imaging process is known. Generally, before the imaging process, a coating roller containing a treatment agent and a conveyance roller on the side facing through the medium support the medium, and when the medium passes, the treatment agent is applied by the coating roller. In this case, since the amount of the treatment agent applied affects the image quality, it is required to uniformly apply the treatment agent to the medium.

[0003] As a technique for applying such a treatment agent, a coating roller drive control unit is provided that controls the peripheral speed of the coating roller to be slower than the conveyance speed of the recording medium during conveyance of the recording medium. When the peripheral speed of the coating roller controlled by the coating roller drive control unit becomes equal to or higher than the leveling rotation speed of the coating roller, a pressure roller is pressed against the coating roller, and the recording medium is sandwiched and conveyed between the coating roller and the pressure roller to transfer the treatment liquid to the recording medium, thereby suppressing the slack of the recording medium behind the treatment liquid application unit and enabling proper treatment (for example, Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in conventional technology, a coating roller with an elastic layer on its outer circumference is sandwiched between a fixed roller and a pressure roller, forming a nip with each of the rollers. If the coating roller is left in a non-rotating state, two recesses remain on the coating roller due to the 180° pitch of the nip at the top and bottom. When media is inserted into these nip areas and the coating roller rotates in accordance with the linear speed of the media, the amount of processing agent applied to these recesses increases, resulting in a banding-like uneven coating with a pitch covering half the circumference of the coating roller.

[0005] The present invention has been made in view of the above, and aims to provide a processing agent liquid coating apparatus and an image forming apparatus that can suppress the occurrence of banding-like uneven coating on a recording medium due to the processing agent and improve the uniformity of the application of the processing agent. [Means for solving the problem]

[0006] To solve the above-mentioned problems and achieve the objective, the present invention provides a processing agent coating apparatus mounted on an image forming apparatus, comprising: a coating roller for coating a processing agent onto a conveyed recording medium; a pressure roller for applying pressure to the coating roller; a supply roller for supplying the processing agent to the coating roller; and a first control unit that rotates the coating roller for a predetermined rotation time between the time job information is acquired by the image forming apparatus and the time the recording medium reaches the coating roller. [Effects of the Invention]

[0007] According to the present invention, it is possible to suppress the occurrence of banding-like uneven coating on the recording medium due to the processing agent and to improve the uniformity of the processing agent coating. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 shows an example of the overall configuration of an image forming apparatus according to an embodiment. [Figure 2]Figure 2 shows another example of the overall configuration of the image forming apparatus according to the embodiment. [Figure 3] Figure 3 shows an example of the configuration of the pre-coating unit of the image forming apparatus according to the embodiment. [Figure 4] Figure 4 shows an example of the configuration of the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. [Figure 5] Figure 5 shows an example of the hardware configuration of an image forming apparatus according to an embodiment. [Figure 6] Figure 6 is a diagram illustrating the control operation of the coating roller in the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. [Figure 7] Figure 7 shows an example of the configuration of a functional block in an image forming apparatus according to an embodiment. [Figure 8] Figure 8 shows the preparation state of the coating section of a conventional image forming apparatus before the application of the treatment agent. [Figure 9] Figure 9 shows the state of the processing agent during application in the coating section of a pre-coating unit of a conventional image forming apparatus. [Figure 10] Figure 10 shows a state in which banding-like uneven coating occurs in media coated with a processing agent using a pre-coating unit of a conventional image forming apparatus. [Figure 11] Figure 11 shows the non-operating state of the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. [Figure 12] Figure 12 shows the preparation state of the coating section of the pre-coating unit of the image forming apparatus according to the embodiment, before the application of the processing agent. [Figure 13] Figure 13 shows the state of the coating section of the pre-coating unit of the image forming apparatus according to the embodiment when the processing agent is applied. [Figure 14] Figure 14 shows the state of the media to which the processing agent has been applied in the pre-coating unit of the image forming apparatus according to the embodiment. [Figure 15] Figure 15 shows an example of the configuration of the functional block of the image forming apparatus according to Modification 1. [Modes for carrying out the invention]

[0009] Embodiments of the processing agent coating apparatus and image forming apparatus according to the present invention will be described in detail below with reference to the drawings. Furthermore, the present invention is not limited by the following embodiments, and the components in the following embodiments include those that are easily conceivable by those skilled in the art, substantially identical, and so-called equivalents. Moreover, various omissions, substitutions, modifications, and combinations of components can be made without departing from the spirit of the following embodiments.

[0010] (Overall configuration of the image forming apparatus) Figure 1 shows an example of the overall configuration of the image forming apparatus according to the embodiment. Figure 2 shows another example of the overall configuration of the image forming apparatus according to the embodiment. The overall configuration of the image forming apparatus 100 according to this embodiment will be described with reference to Figures 1 and 2.

[0011] The image forming apparatus 100 shown in Figure 1 is a commercial printing press that forms images on a medium (recording medium) such as paper using an inkjet method. The image forming apparatus 100 includes a paper feeding unit 101, a pre-coating unit 108, a resist unit 102, an image forming unit 103, a drying unit 104, a cooling unit 105, an inversion unit 106, and a paper discharge unit 107.

[0012] The paper feeding unit 101 is a unit that separates and transports media one sheet at a time from the paper feeding tray 120. The separated media are fed to the pre-coating unit 108. The paper feeding unit 101 can switch the media transport path depending on whether or not pre-coating of the processing agent is performed in the pre-coating unit 108. If pre-coating is not performed, the media is transported along path b as shown in Figure 1, and if pre-coating is performed, it is transported along path a. In this embodiment, the paper feeding unit 101 will be described as transporting the media along path a, since it is assumed that pre-coating is performed on the media in the pre-coating unit 108.

[0013] The precoating unit 108 is a unit (treatment agent liquid application device) for applying a treatment agent for precoating to one or both sides of the media conveyed along the path a from the paper feeding unit 101 and fed. The media precoated with the treatment agent by the precoating unit 108 is conveyed to the resist unit 102.

[0014] The resist unit 102 is a unit for properly correcting the posture of the media conveyed from the precoating unit 108. The media whose posture has been corrected by the resist unit 102 is conveyed to the imaging unit 103.

[0015] The imaging unit 103 is a unit for performing imaging printing by ejecting ink onto the media conveyed from the resist unit 102. As shown in FIG. 1, the imaging unit 103 includes an imaging conveyance drum 103a and an inkjet head 103b.

[0016] The imaging conveyance drum 103a is a conveyance drum for rotationally conveying the media conveyed from the resist unit 102 to the inkjet head 103b side. The inkjet head 103b is a discharge head for discharging ink onto the media conveyed by the imaging conveyance drum 103a to perform imaging printing.

[0017] The media subjected to imaging printing by the imaging unit 103 is conveyed to the drying unit 104.

[0018] The drying unit 104 is a unit for drying the media conveyed from the imaging unit 103. In the example of the image forming apparatus 100 shown in FIG. 1, one drying unit 104 is provided, but it is not limited thereto, and a plurality of drying units may be provided according to the drying conditions. The media dried by the drying unit 104 is conveyed to the cooling unit 105.

[0019] The cooling unit 105 is a unit that cools the dried media transported from the drying unit 104. The media cooled by the cooling unit 105 is then transported to the inversion unit 106.

[0020] The inversion unit 106, when printing on both sides of the media transported from the cooling unit 105, inverts the media by switching it back in path d, as shown in Figure 1, and transports it from path e to the double-sided transport path 110. The media transported to the double-sided transport path 110 is re-feed to the resist unit 102, where it is image-printed on the second side, which is the reverse side of the first side that has already been image-printed in the image-printing unit 103. In addition, when printing on only one side of the media transported from the cooling unit 105, or when double-sided printing has already been done, the inversion unit 106 transports the media to the paper discharge unit 107 via path c, as shown in Figure 1.

[0021] The paper output unit 107 is a unit that outputs the media transported from the reversing unit 106 to the paper output tray.

[0022] In the image forming apparatus 100 shown in Figure 1, when the media to be printed on both sides is inverted by the inversion unit 106, an example is shown in which the media is re-feed in the resist unit 102, that is, downstream of the pre-coating unit 108. However, as in the image forming apparatus 100a shown in Figure 2, the media may be re-feed upstream of the pre-coating unit 108. In the image forming apparatus 100a shown in Figure 2, an example is shown in which the media is re-feed in the paper feed unit 101a upstream of the pre-coating unit 108. In Figure 2, the configuration of the units downstream of the image-making unit 103 is the same as in Figure 1, so it is omitted from the illustration. The media separated and transported from the paper feed tray 120 in the paper feed unit 101a is pre-coated with a processing agent in the pre-coating unit 108, then its orientation is corrected in the resist unit 102a, and then it is transported to the image-making unit 103. In the case of double-sided printing, as in Figure 1, the media inverted by the inversion unit 106 is re-feeded by the paper feed unit 101a upstream of the pre-coating unit 108 via the double-sided transport path 110a, and transported back to the pre-coating unit 108. In the pre-coating unit 108, the processing agent is pre-coated to the second side, which is the back side of the first side that has already been pre-coated and image-printed, and image printing is performed on the second side by the image-printing unit 103.

[0023] (Configuration of the pre-coating unit) Figure 3 shows an example of the configuration of the pre-coating unit of the image forming apparatus according to the embodiment. Figure 4 shows an example of the configuration of the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. The configuration of the pre-coating unit 108 of the image forming apparatus 100 according to this embodiment will be described with reference to Figures 3 and 4.

[0024] As shown in Figure 3, the pre-coating unit 108 includes a coating section 108a, inlet rollers 301-305, outlet rollers 306-309, purge rollers 310-313, a re-inlet roller 314, and outlet rollers 315 and 316.

[0025] The coating unit 108a is a device that enters the pre-coating unit 108 from direction H and applies a treatment agent to the media conveyed by the inlet rollers 301-305. Details of the configuration of the coating unit 108a will be described later.

[0026] The inlet rollers 301-305 are conveying rollers that transport the media that has entered the pre-coating unit 108 from direction H along direction A to the coating section 108a.

[0027] The exit rollers 306-309 are rollers that transport the media coated with the treatment agent in the coating section 108a along directions B and C shown in Figure 3. When the treatment agent is applied to both sides of the media, the media is coated on the first surface in the coating section 108a, passes through the exit rollers 306-309, and is then transported along direction D by the purge roller 310 via a branching claw (not shown). On the other hand, when the treatment agent is applied to only one side of the media, the media is coated on the first surface in the coating section 108a, passes through the exit rollers 306-309, and is then transported along direction J by the exit rollers 315 and 316 via a branching claw (not shown) to the resist unit 102.

[0028] The purge roller 310 is a conveying roller that transports the media coated with the treatment agent on its first surface to the purge rollers 311-313 for switchback.

[0029] The purge rollers 311-313 are transport rollers that transport the media conveyed by the purge roller 310 along directions E and G shown in Figure 3, and then switch back. The media that has been switched back by the purge rollers 311-313 is transported again to the coating section 108a along direction F by the re-entry roller 314, and the treatment agent is applied to the second surface. The paths in directions E and G by the purge rollers 311-313 can also be used as purging paths.

[0030] The re-entry roller 314 is a conveying roller that transports the media, which has been switched back by the purge rollers 311-313, to the coating section 108a along direction F.

[0031] The exit rollers 315 and 316 are conveying rollers that transport the media, which has been conveyed along directions B and C by the exit rollers 307 to 309, to the resist unit 102 along direction J.

[0032] Furthermore, as shown in the image forming apparatus 100a in Figure 2, when the media inverted by the inversion unit 106 is re-feed upstream of the pre-coating unit 108, it is possible to apply the treatment agent to both sides of the media in the pre-coating unit 108 before it is transported to the resist unit 102a. Alternatively, the treatment agent may be applied only to the first side in the pre-coating unit 108 and then transported to the resist unit 102a, where an image is printed on the first side, and then the media is transported via the double-sided transport path 110a to the second side in the pre-coating unit 108. In this case, since there is no need to switch back the media within the pre-coating unit 108, the pre-coating unit 108 may not include the purge rollers 310-313 and the re-entry roller 314.

[0033] Next, the specific configuration of the coating section 108a of the pre-coating unit 108 will be described with reference to Figure 4.

[0034] As shown in Figure 4, the coating section 108a includes a coating roller 201, a fixed roller 202, a squeeze roller 203, a pressure roller 204, a press roller 205, a pan for the processing agent liquid 211, an inlet sensor S1, and an outlet sensor S2. As shown in Figure 4, the rollers are arranged from bottom to top in the order of squeeze roller 203, fixed roller 202, coating roller 201, pressure roller 204, and press roller 205.

[0035] The coating roller 201 is a roller that applies a liquid treatment agent supplied from the surface of the fixed roller 202 to the underside of the media conveyed from the upstream conveying path 212 by rotational motion. The core of the coating roller 201 is made of, for example, SUS303. In addition, as shown in Figure 4, the coating roller 201 is provided with an elastic layer 201a on its outer circumference. The elastic layer 201a is made of, for example, chloroprene rubber.

[0036] The fixed roller 202 is a supply roller that rotates to supply the processing agent supplied from the squeeze roller 203 to the coating roller 201. The fixed roller 202 is a metal roller made of, for example, SUS303.

[0037] The squeeze roller 203 is impregnated with the treatment agent contained in the treatment agent liquid pan 211 and supplies the treatment agent to the fixed roller 202 by rotational motion. The squeeze roller 203 also has the function of agitating the treatment agent contained in the treatment agent liquid pan 211. Furthermore, the squeeze roller 203 has an elastic layer such as chloroprene rubber on its outer circumference, and its core is made of, for example, SUS303.

[0038] The pressure roller 204 is a roller that applies pressure to the coating roller 201 from above. Furthermore, when media is transported to the coating roller 201 from the upstream transport path 212, the pressure roller 204 applies pressure to the media against the coating roller 201. The pressure roller 204 is a metal roller formed, for example, from SUS303.

[0039] The press roller 205 applies a downward load to the pressure roller 204 and the coating roller 201, and rotates together with the rotation of the pressure roller 204. The press roller 205 has an elastic layer made of chloroprene rubber or the like on its outer circumference, and its core is made of, for example, SUS303.

[0040] The media transported from the upstream transport path 212 is coated with processing liquid by the coating roller 201 and then transported via the downstream transport path 213 to the exit roller 306 side shown in Figure 3. The coating roller 201, fixed roller 202, squeeze roller 203, and pressure roller 204 are all rotated by the same drive source, the motor 206 described later. Of these, the coating roller 201 and squeeze roller 203 rotate clockwise in the view of Figure 4, while the fixed roller 202 and pressure roller 204 rotate counterclockwise in the view of the same figure.

[0041] The treatment agent liquid pan 211 is a pan for storing liquid treatment agents.

[0042] The inlet sensor S1 is a sensor that detects media being transported along the upstream transport path 212. The outlet sensor S2 is a sensor that detects media being transported along the downstream transport path 213 after the processing agent has been applied by the coating roller 201.

[0043] In the configuration of the coating section 108a as described above, as shown in Figure 4, a nip section 214 is formed between the coating roller 201, which has an elastic layer 201a on its outer circumference, and the pressure roller 204, and a nip section 215 is formed between the coating roller 201 and the fixed roller 202. In the nip section 214, the elastic layer 201a of the coating roller 201 becomes concave due to nip pressure from the pressure roller 204. Similarly, in the nip section 215, the elastic layer 201a of the coating roller 201 becomes concave due to nip pressure from the fixed roller 202. Media conveyed from the upstream conveying path 212 passes through the nip section 214, thereby having the treatment agent applied from the coating roller 201.

[0044] (Hardware configuration of image forming apparatus) Figure 5 shows an example of the hardware configuration of the image forming apparatus according to this embodiment. The hardware configuration of the image forming apparatus 100 according to this embodiment will be described with reference to Figure 5.

[0045] As shown in Figure 5, the image forming apparatus 100 includes a CPU (Central Processing Unit) 401, a ROM (Read Only Memory) 402, a RAM (Random Access Memory) 403, an NVRAM (Non-Volatile Random Access Memory) 404, an external device connection I / F 408, a network I / F 409, a coating roller driver 411, a transport roller driver 412, a sub-scanning driver 413, a sensor I / F 414, an inkjet head driver 420, an operation panel 430, and a separation drive circuit 440.

[0046] The CPU 401 is an arithmetic unit that controls the entire image forming apparatus 100. The ROM 402 is a non-volatile memory device that stores programs such as the IPL (Initial Program Loader). The RAM 403 is a volatile memory device used as the work area for the CPU 401.

[0047] NVRAM404 is a non-volatile memory device that stores various data such as programs and retains various data even when the power supply to the image forming apparatus 100 is turned off.

[0048] The External Device Connection I / F408 is an interface that connects to external devices such as PCs (Personal Computers) via USB (Universal Serial Bus) cables, etc., and communicates control signals and data to be printed between the external device and the interface.

[0049] Network I / F409 is a TCP (Transmission Control Protocol) / IP (Internet Protocol) compliant interface for data communication via the Internet or a LAN (Local Area Network), etc. Network I / F409 may also be a wired communication interface compliant with Ethernet®, etc., or a wireless communication interface compliant with Wi-Fi®, etc.

[0050] The coating section roller driver 411 is a drive circuit for driving a motor 206 that rotates the coating roller 201, fixed roller 202, squeeze roller 203, and pressure roller 204 of the pre-coating unit 108.

[0051] The transport roller driver 412 is a drive circuit for independently rotating the inlet rollers 301-305, outlet rollers 306-309, purge rollers 310-313, re-inlet roller 314, and outlet rollers 315 and 316 of the pre-coating unit 108.

[0052] The sub-scanning driver 413 is a drive circuit for rotating the image transport drum 103a of the image unit 103 in order to transport the media in the transport direction, i.e., the sub-scanning direction.

[0053] Sensor I / F414 is an interface for receiving signals detected by sensors such as the inlet sensor S1 and the outlet sensor S2.

[0054] The inkjet head driver 420 is a drive circuit for controlling the ejection operation of the inkjet head 103b.

[0055] The control panel 430 is a device that displays setting information and various screens for the image forming apparatus 100, and includes a touch panel and alarm lamps for receiving user input.

[0056] The separation drive circuit 440 is a drive circuit for moving the fixed roller 202 and the pressure roller 204 in a direction away from the coating roller 201, or for moving them to contact the coating roller 201 to form nip portions 214 and 215. The method of moving the fixed roller 202 and the pressure roller 204 by the separation drive circuit 440 can be a known method, such as the one described in Japanese Patent Application Publication No. 2012-196955, which utilizes a TR arm, a TR spring, and a TR cam.

[0057] Furthermore, the CPU 401, ROM 402, RAM 403, NVRAM 404, external device connection I / F 408, network I / F 409, coating roller driver 411, transport roller driver 412, sub-scanning driver 413, sensor I / F 414, inkjet head driver 420, operation panel 430, and separation drive circuit 440 are capable of data communication with each other via bus 410, which includes an address bus and a data bus.

[0058] Furthermore, the hardware configuration of the image forming apparatus 100 shown in Figure 5 is an example, and it is not necessary to include all of the components shown in Figure 5, or other components may be included.

[0059] (Control operation of the coating roller) Figure 6 is a diagram illustrating the control operation of the coating roller in the coating section of the pre-coating unit of the image forming apparatus according to this embodiment. The control operation of the coating section 108a of the pre-coating unit 108 of the image forming apparatus 100 according to this embodiment will be explained with reference to Figure 6.

[0060] The coating unit 108a further includes a motor 206 and an encoder 207, as shown in Figure 6.

[0061] Motor 206 is an electric motor for rotating the coating roller 201, the fixed roller 202, the squeeze roller 203, and the pressure roller 204.

[0062] The encoder 207 is a sensor that detects the rotational speed of the motor 206. The encoder 207 transmits the detected rotational speed of the motor 206 to the coating roller driver 411, which will be described later.

[0063] As described above, the coating section roller driver 411 rotates the motor 206, which rotates the coating roller 201, the fixed roller 202, the squeeze roller 203, and the pressure roller 204, by outputting a drive current to the motor 206. The encoder 207 then detects the rotational speed of the motor 206 and feeds the detected rotational speed back to the coating section roller driver 411. In other words, the coating section roller driver 411 performs feedback control by comparing the set rotational speed (target rotational speed) with the rotational speed fed back from the encoder 207, thereby rotating the motor 206 at the target rotational speed and rotating the coating roller 201, the fixed roller 202, the squeeze roller 203, and the pressure roller 204 at the desired linear speed. Furthermore, it is desirable that the motor 206 be an AC servo motor with high output and high responsiveness.

[0064] (Configuration and operation of the functional blocks of the image forming apparatus) Figure 7 shows an example of the configuration of a functional block in an image forming apparatus according to this embodiment. The configuration and operation of the functional block of the image forming apparatus 100 according to this embodiment will be described with reference to Figure 7.

[0065] As shown in Figure 7, the image forming apparatus 100 includes a job acquisition unit 500, a sensor detection unit 501, a roller control unit 502 (first control unit), a transport control unit 503, a storage unit 504, and a separation control unit 505 (second control unit).

[0066] The job acquisition unit 500 is a functional unit that acquires job information, including print data to be printed, from external devices via a network interface 409 or the like.

[0067] The sensor detection unit 501 is a functional unit that acquires detection signals from the inlet sensor S1 and outlet sensor S2, which detect the media, via the sensor I / F 414.

[0068] The roller control unit 502 is a functional unit that controls the rotation of the coating roller 201, fixed roller 202, squeeze roller 203, and pressure roller 204 via the coating roller driver 411. Specifically, the roller control unit 502 refers to a lookup table stored in the storage unit 504 (described later) and rotates the coating roller 201 at an optimal linear speed corresponding to the preset type of media being transported in the image forming apparatus 100. In addition, to suppress the occurrence of uneven coating caused by recesses formed on the coating roller 201, the roller control unit 502 controls the rotation of the coating roller 201 for a predetermined rotation time between the time job information is acquired by the job acquisition unit 500 and the time the media is fed to the coating unit 108a. The operation of rotating the coating roller 201 for this rotation time will be described in detail in Figures 11 to 14.

[0069] The transport control unit 503 is a functional unit that controls the rotation of the inlet rollers 301-305, outlet rollers 306-309, purge rollers 310-313, re-inlet roller 314, and outlet rollers 315 and 316 of the pre-coating unit 108 via the transport roller driver 412.

[0070] The memory unit 504 is a functional unit that stores a lookup table (an example of a table) that associates the type of media with the optimal linear speed of the coating roller 201. The memory unit 504 is implemented by the ROM 402 or NVRAM 404 shown in Figure 5.

[0071] The separation control unit 505 is a functional unit that controls the movement of the fixed roller 202 and the pressure roller 204 via the separation drive circuit 440, such as moving them in a direction away from the coating roller 201, or moving them to contact the coating roller 201 to form nip portions 214 and 215.

[0072] The job acquisition unit 500, sensor detection unit 501, roller control unit 502, transport control unit 503, and separation control unit 505 described above are implemented by the execution of a program by the CPU 401 shown in Figure 5. At least a portion of the job acquisition unit 500, sensor detection unit 501, roller control unit 502, transport control unit 503, and separation control unit 505 may be implemented by hardware circuits such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application Specific Integrated Circuits).

[0073] It should be noted that the functional units of the image forming apparatus 100 shown in Figure 7 are conceptual representations of their functions and are not limited to this configuration. In other words, each functional unit of the image forming apparatus 100 does not need to be configured as a distinct software module as a block as shown in Figure 7; the functions of each functional unit can be realized as a whole when a program is executed in the image forming apparatus 100. For example, multiple functional units shown as independent functional units in the image forming apparatus 100 in Figure 7 may be configured as a single functional unit. On the other hand, the functions of one functional unit in the image forming apparatus 100 shown in Figure 7 may be divided into multiple functions and configured as multiple functional units.

[0074] (Explanation of the operation of the pre-coating unit in a conventional image forming apparatus) Figure 8 shows the preparation state before application of the processing agent in the coating section of a conventional pre-coating unit of an image forming apparatus. Figure 9 shows the state during application of the processing agent in the coating section of a conventional pre-coating unit of an image forming apparatus. Figure 10 shows the state in which banding-like uneven coating occurs on media coated with the processing agent by a conventional pre-coating unit of an image forming apparatus. The operation of the pre-coating unit of a conventional image forming apparatus will be explained with reference to Figures 8 to 10.

[0075] Figure 8 shows the configuration of the coating section of a pre-coating unit in a conventional image forming apparatus, specifically the coating roller 1201, fixed roller 1202, and pressure roller 1204. The coating roller 1201 has an elastic layer 1201a on its outer circumference. In this configuration, a nip portion 1214 is formed between the coating roller 1201, which has the elastic layer 1201a on its outer circumference, and the pressure roller 1204, and a nip portion 1215 is formed between the coating roller 1201 and the fixed roller 1202. Before job information is acquired, similar to the image forming apparatus 100 according to this embodiment described later, the coating roller 1201 and the fixed roller 1202 are separated, and the coating roller 1201 and the pressure roller 1204 are separated, and the coating roller 1201, fixed roller 1202, and pressure roller 1204 are in a non-rotating state.

[0076] When the image forming apparatus acquires job information, media is fed from the paper feeding unit, so the preparation for the coating operation by the coating roller 1201 must be completed by the time the media reaches the coating section of the pre-coating unit. For this reason, conventionally, as shown in Figure 8, when the image forming apparatus acquires job information, the coating roller 1201, the fixed roller 1202, and the pressure roller 1204 remain in a non-rotating state, with the fixed roller 1202 and the pressure roller 1204 in contact with the coating roller 1201, forming a nip portion 1214 between the coating roller 1201 and the pressure roller 1204, and a nip portion 1215 between the coating roller 1201 and the fixed roller 1202, and the apparatus remains in standby mode.

[0077] Then, as shown in Figure 9, when the media P reaches the coating area and the coating operation is performed by the coating roller 1201, the coating roller 1201, the fixed roller 1202, and the pressure roller 1204 begin to rotate. However, because they were waiting in the state shown in Figure 8 above, in the part of the elastic layer 1201a of the coating roller 1201 that was receiving nip pressure from the fixed roller 1202 and the pressure roller 1204, two recesses 1214a and 1215a are created at a 180-degree pitch, as shown in Figure 9. As a result, when the media P is inserted into the nip portion between the coating roller 1201 and the pressure roller 1204, the amount of processing agent increases in the aforementioned recesses 1214a and 1215a, causing banding-like uneven coating with a pitch of half the circumference of the coating roller 1201, as shown in Figure 10. The image forming apparatus 100 according to this embodiment can suppress the occurrence of such banding-like uneven coating due to the processing agent, as will be explained below.

[0078] (Detailed operation of the coating section of the pre-coating unit of the image forming apparatus) Figure 11 shows the non-operating state of the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. Figure 12 shows the preparation state before the application of the processing agent to the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. Figure 13 shows the state during the application of the processing agent to the coating section of the pre-coating unit of the image forming apparatus according to the embodiment. Figure 14 shows the state of the media to which the processing agent has been applied in the pre-coating unit of the image forming apparatus according to the embodiment. Referring to Figures 11 to 14, the details of the operation of the coating section 108a of the pre-coating unit 108 of the image forming apparatus 100 according to this embodiment will be described.

[0079] In the coating section 108a of the pre-coating unit 108 according to this embodiment, before job information is acquired by the job acquisition unit 500, as shown in Figure 11, the separation control unit 505 separates the coating roller 201 and the fixed roller 202 via the separation drive circuit 440 to release the nip pressure, and separates the coating roller 201 and the pressure roller 204 to release the nip pressure. In this state, the roller control unit 502 keeps the coating roller 201, the fixed roller 202, and the pressure roller 204 in a non-rotating state.

[0080] Next, when job information is acquired by the job acquisition unit 500, media is fed from the paper feed unit 101, as in the conventional case described above. Therefore, the preparation for the coating operation by the coating roller 201 must be completed by the time the media reaches the coating section 108a of the pre-coating unit 108. However, when the coating roller 201 is rotated, the processing agent supplied from the squeeze roller 203 and the fixed roller 202 comes into contact with the air. When exposed to air, the water in the processing liquid evaporates, increasing the viscosity of the processing liquid and thus degrading its quality. Furthermore, rotating the coating roller 201 quickly increases the frequency with which the processing liquid comes into contact with the air.

[0081] Therefore, in this embodiment, when job information is acquired by the job acquisition unit 500, the separation control unit 505 first brings the fixed roller 202 and the pressure roller 204 into contact with the coating roller 201, respectively, to form a nip portion 214 between the coating roller 201 and the pressure roller 204, and a nip portion 215 between the coating roller 201 and the fixed roller 202. Then, the roller control unit 502 controls the rotation of the coating roller 201 for a predetermined rotation time, as shown in Figure 12, between the time the job information is acquired by the job acquisition unit 500 and the time the media is fed into the coating unit 108a. This suppresses the formation of recesses on the coating roller 201 before the processing agent is applied to the media, and eliminates any recesses that have already formed, thereby suppressing the occurrence of banding-like uneven coating due to the processing agent and improving the uniformity of the processing agent application.

[0082] Here, the longer the coating roller 201 is used, the greater the degree of deterioration of the elastic layer 201a of the coating roller 201, and the longer it takes for the aforementioned depressions formed in the elastic layer 201a to disappear. Therefore, it is desirable for the roller control unit 502 to determine the rotation time based on, for example, the usage time of the coating roller 201. This makes it possible to more reliably eliminate the depressions in the coating roller 201. Here, the usage time can be, for example, the cumulative processing time for the job information acquired by the job acquisition unit 500, or a time proportional to the number of media used to process the job information.

[0083] In this case, as shown in Figure 12, the roller control unit 502 rotates the coating roller 201, the fixed roller 202, and the pressure roller 204 at a rotational speed lower than the linear speed corresponding to the media, for the aforementioned rotational time. By slowly rotating the coating roller 201, the fixed roller 202, and the pressure roller 204, it is possible to suppress the increase in viscosity of the processing agent and to suppress the formation of depressions due to nip pressure received from the fixed roller 202 and the pressure roller 204.

[0084] Then, as shown in Figure 13, when the media P reaches the coating roller 201 and the coating operation is performed by the coating roller 201, the roller control unit 502 rotates the coating roller 201, the fixed roller 202, and the pressure roller 204 at a rotational speed corresponding to the linear speed of the media P (the linear speed defined in the lookup table stored in the memory unit 504). Here, it is sufficient to determine that the media P has arrived at the coating roller 201 when the inlet sensor S1 detects the media P. As a result, the processing agent is applied to the media P with the formation of recesses suppressed by the coating roller 201, and as shown in Figure 14, the occurrence of banding-like uneven coating due to the processing agent can be suppressed.

[0085] As described above, in the pre-coating unit 108 of the image forming apparatus 100 according to this embodiment, the coating roller 201 applies the processing agent to the conveyed media, the pressure roller 204 applies pressure to the coating roller 201, the fixed roller 202 supplies the processing agent to the coating roller 201, and the roller control unit 502 rotates the coating roller 201 for a predetermined rotation time between the time job information is acquired by the image forming apparatus 100 and the time the media reaches the coating roller 201. This suppresses the occurrence of banding-like uneven coating by the processing agent on the media and improves the uniformity of the processing agent application.

[0086] Furthermore, in the pre-coating unit 108 of the image forming apparatus 100 according to this embodiment, the roller control unit 502 determines the rotation time based on the usage time of the coating roller 201. This makes it possible to more reliably eliminate the recesses of the coating roller 201.

[0087] (Variation 1) The image forming apparatus according to Modification 1 will be described, focusing on the differences from the image forming apparatus 100 according to the above embodiment. In this modification, the operation of detecting rotational unevenness of the coating roller 201 caused by a recess formed in the coating roller 201 and rotating the coating roller 201 until the rotational unevenness is reduced will be described. The overall configuration and hardware configuration of the image forming apparatus according to this modification are the same as those described in the above embodiment.

[0088] Figure 15 shows an example of the configuration of the functional block of the image forming apparatus according to Modification 1. The configuration and operation of the functional block of the image forming apparatus 100b according to this modification will be explained with reference to Figure 15.

[0089] As shown in Figure 15, the image forming apparatus 100b includes a job acquisition unit 500, a sensor detection unit 501, a roller control unit 502 (first control unit), a transport control unit 503, a storage unit 504, a separation control unit 505 (second control unit), and a rotation unevenness detection unit 506 (detection unit). The operation of the job acquisition unit 500, the sensor detection unit 501, the transport control unit 503, the storage unit 504, and the separation control unit 505 is the same as the operation described in the above embodiment.

[0090] As described above, when the coating roller 201 (elastic layer 201a) rotates with a recess formed in it, the contact state of the fixed roller 202 and the pressure roller 204 with respect to the coating roller 201 fluctuates in the recess, resulting in uneven rotation of the coating roller 201. Therefore, in this modified example, the rotational unevenness of the coating roller 201 is detected, and the coating roller 201 is rotated until the rotational unevenness is reduced.

[0091] The rotation unevenness detection unit 506 is a functional unit that detects rotation unevenness of the coating roller 201. The rotation unevenness detection unit 506 detects rotation unevenness of the coating roller 201 based on the rotation speed of the motor 206 detected, for example, by the encoder 207. As rotation unevenness, for example, the amount of fluctuation in the rotation speed of the motor 206 may be detected. Alternatively, instead of the encoder 207 that detects the rotation speed of the motor 206, an encoder that detects the rotation speed of the coating roller 201 itself may be used. Furthermore, instead of using the encoder 207, the rotation unevenness detection unit 506 may use a dedicated sensor for detecting rotation unevenness of the coating roller 201.

[0092] The roller control unit 502 controls the application roller 201 to rotate for a predetermined rotation time between the time job information is acquired by the job acquisition unit 500 and the time the media is fed to the application unit 108a, in order to suppress the occurrence of uneven application caused by recesses formed on the application roller 201. Here, the roller control unit 502 rotates the application roller 201 using the time until the rotation unevenness detected by the rotation unevenness detection unit 506 falls below a predetermined value as the rotation time.

[0093] This allows the coating roller 201 to be rotated until rotational unevenness is reduced, making it possible to determine how well the recesses on the coating roller 201 have been eliminated, thereby suppressing the occurrence of banding-like coating unevenness caused by the treatment agent.

[0094] (Modification 2) This section will explain the differences between the image forming apparatus 100 in Modification 1 and Modification 2, focusing on the differences between the two. In this modification, we will describe the operation of storing the time it took for past rotational unevenness to decrease and determining the rotation time of the coating roller 201 based on that time. The overall configuration, hardware configuration, and functional block configuration of the image forming apparatus in this modification are the same as those described in Modification 1 above.

[0095] The roller control unit 502 stores in the storage unit 504 the time required from the start of rotation of the coating roller 201 until the rotational unevenness detected by the rotational unevenness detection unit 506 falls below a predetermined value. In other words, the roller control unit 502 stores in the storage unit 504 the actual time required until the rotational unevenness is reduced.

[0096] The roller control unit 502 controls the rotation of the coating roller 201 for a predetermined rotation time between the time job information is acquired by the job acquisition unit 500 and the time the media is fed to the coating unit 108a, in order to suppress the occurrence of uneven coating caused by recesses formed on the coating roller 201. Here, the roller control unit 502 determines the above rotation time based on the time required for the rotation unevenness detected by the rotation unevenness detection unit 506, which is stored in the storage unit 504, to fall below a predetermined value, and controls the rotation of the coating roller 201 for that rotation time.

[0097] In this way, the rotation time of the coating roller 201 is determined based on the time required for the rotational unevenness detected by the rotational unevenness detection unit 506 to fall below a predetermined value. By rotating the coating roller 201 for a time based on past performance, the recesses formed on the coating roller 201 can be eliminated more reliably. This makes it possible to suppress the occurrence of banding-like coating unevenness caused by the treatment agent.

[0098] In the embodiments and their respective modifications described above, if at least one of the functional units of the image forming apparatus 100, 100a, and 100b is implemented by program execution, the program is provided pre-installed in a ROM or the like. Furthermore, in the embodiments and their respective modifications described above, the program executed by the image forming apparatus 100, 100a, and 100b may be provided as an installable or executable file recorded on a computer-readable recording medium such as a CD-ROM (Compact Disc Read Only Memory), a flexible disk (FD), a CD-R (Compact Disk-Recordable), or a DVD (Digital Versatile Disc). Also, in the embodiments and their respective modifications described above, the program executed by the image forming apparatus 100, 100a, and 100b may be provided by storing it on a computer connected to a network such as the Internet and allowing it to be downloaded via the network. Finally, in the embodiments and their respective modifications described above, the program executed by the image forming apparatus 100, 100a, and 100b may be provided or distributed via a network such as the Internet. Furthermore, in the embodiments and their respective modifications described above, the programs executed by the image forming apparatus 100, 100a, and 100b are configured as modules that include at least one of the functional units described above. In actual hardware, the CPU 401 reads and executes the program from the storage device (e.g., ROM 402, NVRAM 404, etc.), thereby loading and generating the functional units described above onto the main memory (RAM 403).

[0099] The embodiments of the present invention are as follows. <1> A processing agent coating apparatus mounted on an image forming apparatus, A coating roller for applying a processing agent to a conveyed recording medium, A pressure roller that applies pressure to the coating roller, A supply roller that supplies the processing agent to the coating roller, A first control unit rotates the coating roller for a predetermined rotation time between the time job information is acquired by the image forming apparatus and the time the recording medium reaches the coating roller. This is a processing agent liquid coating apparatus equipped with [a specific feature]. <2> The first control unit determines the rotation time based on the usage time of the coating roller. <1> This is a processing agent liquid coating apparatus as described above. <3> The aforementioned usage time is a time proportional to the processing time for the job information, or the number of recording media used to process the job information. <2> This is a processing agent liquid coating apparatus as described above. <4> The system further includes a detection unit for detecting rotational unevenness of the coating roller, The first control unit rotates the coating roller using the time until the rotational unevenness detected by the detection unit falls below a predetermined value as the rotation time. <1> This is a processing agent liquid coating apparatus as described above. <5> A detection unit for detecting rotational unevenness of the coating roller, A storage unit that stores the time required from the start of rotation of the coating roller until the rotational unevenness detected by the detection unit falls below a predetermined value, Furthermore, The first control unit determines the rotation time based on the required time stored in the storage unit. <1> This is a processing agent liquid coating apparatus as described above. <6> The first control unit rotates the coating roller at a rotational speed such that the linear speed is lower than the linear speed corresponding to the recording medium for the duration of the rotation, from the time the job information is acquired by the image forming apparatus until the recording medium reaches the coating roller. <1> ~ <5> It is a processing agent liquid application apparatus as described in any one of the items. <7> The first control unit, after the recording medium has reached the coating roller, rotates the coating roller at a rotational speed corresponding to the linear velocity of the recording medium. <6> This is a processing agent liquid coating apparatus as described above. <8> The image forming apparatus further comprises a second control unit that separates the pressure roller and the supply roller from the coating roller before the job information is acquired by the image forming apparatus, The first control unit, before the image forming apparatus acquires job information, sets the coating roller, the pressure roller, and the supply roller to a non-rotating state. <1> ~ <7> It is a processing agent liquid application apparatus as described in any one of the items. <9> When job information is acquired by the image forming apparatus, the second control unit brings the pressure roller and the supply roller into contact with the coating roller, respectively. <8> This is a processing agent liquid coating apparatus as described above. <10> The aforementioned <1> ~ <9> A processing agent liquid application apparatus as described in any one of the items, The ejection head ejects ink onto the recording medium to which the processing agent has been applied by the processing agent liquid coating apparatus to form an image, This is an image forming apparatus equipped with the following features. [Explanation of Symbols]

[0100] 100, 100a, 100b Image forming apparatus 101, 101a Paper feed unit 102, 102a Resist Unit 103 Image-making unit 103a Image creation transport drum 103b Inkjet Head 104 Drying Unit 105 Cooling Unit 106 Reversal Unit 107 Paper output unit 108 Pre-coating unit 108a Coating area 110, 110a Double-sided transport route 120 Paper feed tray 201 Coating roller 201a Elastic layer 202 Fixed roller 203 Squeezola 204 Pressure Roller 205 Pressing roller 206 Motor 207 encoders 211 Pan for treatment agent solution 212 Upstream transport route 213 Downstream transport route 214, 215 Nip section 301-305 Entrance Laura 306-309 Exit roller 310-313 Purge Roller 314 Re-entry Roller 315, 316 Exit roller 401 CPU 402 ROM 403 RAM 404 NVRAM 408 External device connection interface 409 Network I / F 410 Bus 411 Coating roller driver 412 Conveyor Roller Driver 413 Sub-scanning driver 414 Sensor I / F 420 Inkjet Head Driver 430 Control Panel 440 Separation drive circuit 500 Job Acquisition Department 501 Sensor detection unit 502 Roller Control Unit 503 Transport Control Unit 504 Storage section 505 Separation Control Unit 506 Rotation unevenness detection unit 1201 Coating roller 1201a Elastic layer 1202 Fixed Roller 1204 Pressure Roller 1214 Nip section 1214a Recess 1215 Nip section 1215a Recess P Media S1 Inlet Sensor S2 Exit Sensor [Prior art documents] [Patent Documents]

[0101] [Patent Document 1] Japanese Patent Publication No. 2014-024224

Claims

1. A processing agent coating apparatus mounted on an image forming apparatus, A coating roller for applying a processing agent to a conveyed recording medium, A pressure roller that applies pressure to the coating roller, A supply roller that supplies the processing agent to the coating roller, A first control unit rotates the coating roller for a predetermined rotation time between the time job information is acquired by the image forming apparatus and the time the recording medium reaches the coating roller. A processing agent liquid coating device equipped with the following features.

2. The treatment agent liquid coating apparatus according to claim 1, wherein the first control unit determines the rotation time based on the usage time of the coating roller.

3. The processing agent liquid coating apparatus according to claim 2, wherein the usage time is a time proportional to the processing time for the job information or the number of recording media used to process the job information.

4. The system further includes a detection unit for detecting rotational unevenness of the coating roller, The processing agent liquid coating apparatus according to claim 1, wherein the first control unit rotates the coating roller with the time until the rotational unevenness detected by the detection unit falls below a predetermined value as the rotation time.

5. A detection unit for detecting rotational unevenness of the coating roller, A storage unit that stores the time required from the start of rotation of the coating roller until the rotational unevenness detected by the detection unit falls below a predetermined value, Furthermore, The processing agent liquid coating apparatus according to claim 1, wherein the first control unit determines the rotation time based on the required time stored in the storage unit.

6. The processing agent liquid coating apparatus according to any one of claims 1 to 5, wherein the first control unit rotates the coating roller at a rotational speed such that the linear speed is lower than the linear speed corresponding to the recording medium for the duration of the rotation time, from the time job information is acquired by the image forming apparatus until the recording medium reaches the coating roller.

7. The processing agent liquid coating apparatus according to claim 6, wherein the first control unit rotates the coating roller at a rotational speed corresponding to the linear velocity of the recording medium after the recording medium has reached the coating roller.

8. The image forming apparatus further comprises a second control unit that separates the pressure roller and the supply roller from the coating roller before the job information is acquired by the image forming apparatus, The processing agent liquid coating apparatus according to any one of claims 1 to 5, wherein the first control unit makes the coating roller, the pressure roller, and the supply roller non-rotating before job information is acquired by the image forming apparatus.

9. The processing agent liquid coating apparatus according to claim 8, wherein the second control unit brings the pressure roller and the supply roller into contact with the coating roller, respectively, when job information is acquired by the image forming apparatus.

10. A processing agent liquid coating apparatus according to any one of claims 1 to 5, The ejection head ejects ink onto the recording medium to which the processing agent has been applied by the processing agent liquid coating apparatus to form an image, An image forming apparatus equipped with [a specific feature].

Images