Coating device and image forming system

Abstract

To provide a coating device that is less likely to cause variation in amount of coating liquid to be coated on a sheet.SOLUTION: A coating device includes: a coating roller 52 for coating a sheet P with coating liquid G; a compression roller 57 for forming nip between the coating roller and the compression roller; and a stopper 66 (restriction member) for restricting the compression roller from moving in an alienation direction relative to the coating roller by directly or indirectly abutting on the compression roller when a sheet enters the nip between the coating roller and the compression roller.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] 2. Description of the Related Art Conventionally, there has been known an image forming system in which an image forming apparatus such as an inkjet printer is installed, and which includes an application device that applies a coating liquid to a sheet such as paper (see, for example, Patent Document 1).

[0003] More specifically, in Patent Document 1, the coating device is installed upstream of an image forming device (inkjet printer) and applies a coating liquid (treatment liquid) such as a bleeding suppressant to the surface of a sheet (recording medium) conveyed to the inkjet printer. This makes it difficult for image defects such as bleeding to occur in the image formed on the sheet by the image forming device. In Patent Document 1, the coating device is provided with a storage section (supply pan) in which coating liquid (treatment liquid) is stored, a pumping roller (squeeze roller) that pumps up the coating liquid stored in the storage section, a coating roller that applies the coating liquid pumped up by the pumping roller to a sheet, a pressure roller that forms a nip between the coating roller and the coating roller through which a sheet (recording medium) is transported, and an arm that rotatably holds the pressure roller and biases the pressure roller toward the coating roller, etc. Then, the coating liquid is applied by the coating roller to the sheet transported to the nip between the coating roller and the pressure roller. Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional coating devices, the moment a sheet enters the nip between the coating roller and the pressure roller, the pressure roller jumps up by more than the thickness of the sheet. When this phenomenon occurs, the pressure applied to the coating roller by the pressure roller is weakened, and this causes variation in the amount of coating liquid applied to the sheet by the coating roller at the nip position (uneven coating).

[0005] The present invention has been made to solve the above-mentioned problems, and has an object to provide a coating device and an image forming system in which variation in the amount of coating liquid applied to a sheet is reduced. [Means for solving the problem]

[0006] The coating device according to the present invention includes a coating rotor that applies a coating liquid to a sheet, and a pressure rotor that forms a nip between the coating rotor and the pressure rotor; a pressure arm that biases the pressure rotating body toward the application rotating body; When the sheet enters the nip, the pressure roller Through the pressure arm a limiting member that indirectly contacts the application rotary body to limit movement of the pressure rotary body in a direction away from the application rotary body, and the limiting member is configured to limit movement of the pressure rotary body in a direction away from the application rotary body when the sheet does not enter the nip. Through the pressure arm There is no indirect contact. Effect of the Invention

[0007] According to the present invention, it is possible to provide a coating device and an image forming system in which the amount of coating liquid applied to a sheet is less likely to vary. [Brief description of the drawings]

[0008] [Figure 1] 1 is an overall view showing an image forming system according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a configuration diagram showing a main part of the image forming apparatus. [Diagram 3] 5A to 5C are diagrams illustrating the operation of a main part of the coating device. [Figure 4] 10A and 10B are diagrams illustrating the operation of a main part of a coating device as a comparative example. [Diagram 5] FIG. 13 is a diagram showing a main part of a coating device serving as a first modified example. [Figure 6] 13 is a diagram showing the operation of a main part of a coating device according to a second modified example. FIG. [Figure 7] FIG. 13 is a diagram showing a main part of a coating device serving as a third modified example. [Figure 8] FIG. 13 is a diagram showing a main part of a coating device serving as a fourth modified example. [Figure 9] 9 is an enlarged view showing a main part of the coating apparatus in FIG. 8. [Figure 10] 9 is a longitudinal view of the main part of the coating device of FIG. 8. FIG. [Figure 11] 9 is an enlarged view showing the operation of a main part of the coating device in FIG. 8. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

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

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

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

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

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

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

[0017] Here, the image forming apparatus 1 in this embodiment is for forming a color image, and is provided with a black head 10K, three color heads 10Y, 10M, and 10C for color (yellow, magenta, and cyan), and two color heads 10S1 and 10S2 for coating (special colors), as shown in Fig. 2. These six heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 are radially aligned in the direction of rotation of the conveyor drum 2, facing the conveyor drum 2 with a small gap therebetween. The six heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 have almost the same structure except for the different colors (types) of ink used for printing. The heads 10Y, 10M, 10C, 10K, 10S1, and 10S2 are roughly rectangular units whose main parts are composed of piezoelectric actuators, and which are provided with nozzles that eject ink as a liquid (droplets), an ink tank filled with ink, a control board (control unit), and the like.

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

[0019] Hereinafter, the characteristic coating device 50 in the image forming system 100 according to the present embodiment will be described in detail with reference to FIG. The coating device 50 is a device that applies coating liquid G to a sheet P such as paper. As shown in Fig. 3, the coating device 50 (coating device main section 51) in this embodiment is composed of a coating roller 52 as a coating rotary body, an intermediate roller 53, a pumping roller 54, a pressure roller 57 as a pressure rotary body, a storage section 55, pressure mechanisms 58 to 60, a stopper 66 as a limiting member, and the like.

[0020] The application roller 52 as a rotating application body is a roller member that applies the application liquid G to a sheet, and is disposed so as to extend in the longitudinal direction (the direction perpendicular to the plane of the paper in FIG. 3, which is the direction of the rotation axis). The pressure roller 57 as a pressure rotating body is a roller member that forms a nip between itself and the application roller 52 in the longitudinal direction, and is held by the main body housing so as to be vertically movable. The intermediate roller 53 is a roller member that contacts both the application roller 52 and the draw-up roller 54 . A certain amount of coating liquid G is stored in the storage section 55. The storage section 55 is a substantially rectangular box-shaped member whose longitudinal direction is the direction perpendicular to the paper surface of FIG. The pumping roller 54 functions as a pumping member that pumps up the coating liquid G stored in the storage portion 55.

[0021] The pumping roller 54 carries the coating liquid G in the storage section 55 while rotating in the clockwise direction in Fig. 3. The coating liquid G carried by the pumping roller 54 is transferred to and carried by the intermediate roller 53 (metering roller) rotating in the counterclockwise direction in Fig. 3. The coating liquid G carried by the intermediate roller 53 is adjusted to an appropriate amount (metered) at a contact position with the coating roller 52 rotating in the clockwise direction in Fig. 3, and the appropriate amount of coating liquid G is carried by the coating roller 52. Then, the coating liquid G carried by the coating roller 52 is applied (coating process) to the sheet surface (lower surface) of the sheet P conveyed to the nip between the coating roller 52 and the pressure roller 57. At this time, the pressure roller 57 rotates counterclockwise in FIG. 3 while being pressed by the pressure arm 58 of the pressure mechanisms 58-60.

[0022] The pumping roller 54 is connected to a drive motor 72, and is driven to rotate in a predetermined direction by the drive motor 72 controlled by the control unit. The intermediate roller 53 and the application roller 52 receive drive power from the drive motor 72 via a gear train, and rotate in their respective predetermined directions. The pressure roller 57 is provided at its shaft end with a gear that can be brought into contact with and separated from the above-mentioned gear train, and is configured to be rotatable by the drive power of the drive motor 72 being transmitted thereto.

[0023] The pressure roller 57 is configured to be movable in a direction toward and away from the application roller 52 (up and down) by pressure mechanisms 58-60. The pressure mechanism is composed of a pressure arm 58, a pressure cam 59, a tension spring 60, etc. The pressure arm 58 is held in the main body housing so as to be rotatable around a support shaft 58a, and urges the pressure roller 57 toward the application roller 52. One end of the tension spring 60 is connected to the pressure arm 58, and the other end is connected to a movable plate 69. The movable plate 69 moves up and down by the pressure cam 59, which is rotationally driven by a cam motor 71. When the application process is performed, the pressure roller 57 is moved to the contact position (a position in contact with the application roller 52) shown in Fig. 3(A) by the pressure mechanisms 58-60. On the other hand, when the application process is not performed, the pressure roller 57 is moved to the separation position (a position away from the application roller 52) by the pressure mechanisms 58-60.

[0024] Here, in the application device 50 of this embodiment, a stopper 66 is provided as a limiting member that indirectly abuts against the pressure roller 57 when the sheet P enters the nip between the application roller 52 and the pressure roller 57, thereby limiting the movement of the pressure roller 57 in the direction away from the application roller 52. 3B, when sheet P enters the nip, stopper 66 (limiting member) comes into contact with pressure arm 58 to limit the movement of pressure roller 57 in the separating direction (upward). That is, the upper limit of the movement of pressure roller 57 in the separating direction (upward) is determined by the position where stopper 66 comes into contact with pressure arm 58.

[0025] 3A, the pressure roller 57 is in contact with the application roller 52 until immediately before the sheet P enters the nip between the application roller 52 and the pressure roller 57. At this time, the stopper 66 is not in contact with the pressure arm 58, and a gap H is formed between the two members 58, 66. Then, as shown in FIG. 3B, the moment the leading edge of the sheet P enters the nip between the application roller 52 and the pressure roller 57, the pressure roller 57 is pushed up with force by the thickness of the sheet (the thickness of the sheet P). However, as the pressure arm 58 comes into contact with the stopper 66, the pushing up is kept to a minimum.

[0026] Providing the stopper 66 (limiting member) in this manner can reduce the phenomenon in which the pressure roller 57 jumps up to a thickness greater than the thickness of the sheet P at the moment the sheet P enters the nip between the application roller 52 and the pressure roller 57. This reduces the problem of variation in the amount of application liquid applied to the sheet P by the application roller 52 (uneven application).

[0027] As described above, when the sheet P does not enter the nip, there is a predetermined gap H between the stopper 66 and the pressure arm 58. That is, when the sheet P does not enter the nip, the stopper 66 does not directly or indirectly abut against the pressure roller 57 when the sheet P does not enter the nip between the application roller 52 and the pressure roller 57. In this embodiment, the size of the predetermined gap H is set so that when the thickness of the sheet P is less than a predetermined thickness, the stopper 66 does not abut against the pressure arm 58 when the sheet P passes through the nip, and when the thickness of the sheet P is equal to or greater than the predetermined thickness, the stopper 66 abuts against the pressure arm 58 when the sheet P passes through the nip. This prevents an increase in the load on the motor driving the roller pairs 52, 57 when a sheet P with a thickness less than a predetermined thickness, such as thin paper, passes through the nip, and also suppresses problems such as wrinkles occurring in the sheet P due to the load on the stopper 66 impeding the transport of a weak sheet P (thin paper). On the other hand, when a sheet P with a thickness equal to or greater than a predetermined thickness, such as thick paper, passes through the nip, it is possible to reduce the phenomenon in which the pressure roller 57 jumps up beyond the thickness of the sheet P.

[0028] Specifically, in the case where the stopper 66 (limiting member) is not provided as in the coating device 151 shown in FIG. 4, the pressure roller 57 jumps up to a thickness greater than the thickness of the sheet P at the moment the sheet P enters the nip between the coating roller 52 and the pressure roller 57, as shown in FIG. 4(A) to FIG. 4(B). Then, at the moment the pressure roller 57 jumps up, the pressure on the coating roller 52 is weakened, the coating roller 52 (or the intermediate roller 53) is displaced upward, and a large amount of the coating liquid G passes through the nip between the coating roller 52 and the intermediate roller 53 (or the nip between the intermediate roller 53 and the pumping roller 54) (the transfer of the coating liquid G is insufficient), and the amount of the coating liquid G applied to the sheet P by the coating roller 52 at the nip position varies (uneven application). In particular, when the conveying speed of the sheet P is high or the thickness of the sheet P is large, such a defect becomes noticeable. In order to solve such a problem, it is possible to consider increasing the spring constant of the tension spring 60 to increase the pressure of the pressure roller 57, or to fix the pressure roller 57 so that it does not move up and down. However, the former is likely to cause poor transport due to a delay in the entry of the sheet P into the nip (delay in the transport timing), and the latter is likely to cause poor transport in which the sheet P does not pass through the nip.

[0029] In contrast, in the present embodiment, the pressure roller 57 is permitted to move in the separating direction to a certain extent, and the amount of movement is limited, so that it is possible to reduce the occurrence of various problems as described above. In other words, it is possible to reduce coating unevenness (variation) of the coating liquid G applied to the sheet P without causing a transport failure of the sheet P.

[0030] In this embodiment, a stopper 66 (restricting member) is provided that can indirectly contact the pressure roller 57 via the pressure arm 58 when the sheet P enters the nip between the application roller 52 and the pressure roller 57. That is, the stopper 66 is configured to indirectly contact the pressure roller 57 by contacting the pressure arm 58, which is a member that works in conjunction with the pressure roller 57. In response to this, a stopper 66 (restriction member) may be provided that can directly come into contact with the pressure roller 57 when the sheet P enters the nip between the application roller 52 and the pressure roller 57. That is, the stopper 66 may be provided on the surface of the pressure roller 57, outside the area through which the sheet P passes, or the stopper 66 may be provided on the rotation axis of the pressure roller 57.

[0031] Furthermore, in this embodiment, the application roller 52 is configured to be vertically displaceable, but the application roller 52 may be fixed so as not to be vertically displaceable. In this case as well, it is possible to prevent the pressure roller 57 from jumping up to a thickness greater than the thickness of the sheet P. This makes it possible to suppress fluctuations in the nip width between the pressure roller 57 and the application roller 52 at the moment the sheet P enters, and to suppress fluctuations in the amount of application liquid applied between the leading end of the sheet P and the rest of the sheet P.

[0032] In this embodiment, the stopper 66 serving as a limiting member is made of a rubber material serving as an elastic material. The position of the stopper 66 (gap H with the pressure arm 58) is set according to the thickness of a frequently used sheet P (for example, plain paper). That is, when the sheet P is not conveyed to the nip, there is a gap H between the stopper 66 and the pressure arm 58 as shown in FIG. 3A. Then, when the frequently used sheet P enters the nip and the pressure roller 57 (pressure arm 58) is raised against the bias of the tension spring 60 by the thickness of the frequently used sheet P, the stopper 66 is set to just abut against the pressure arm 58. However, in that case, if a sheet P thicker than the frequently used sheet P is conveyed, it becomes difficult for the sheet P to pass through the nip. Therefore, in this embodiment, the stopper 66 is formed of a rubber material, and when the thick sheet P enters the nip, the stopper 66 abuts against the pressure arm 58 in a state of elastic deformation with good response, thereby preventing poor conveyance of the sheet P. In particular, in this embodiment, the rubber material used for the stopper 66 (restricting member) is urethane rubber having a Shore A hardness within a range of 30 to 70. As a result of extensive research, the inventors of the present application have found that by forming the stopper 66 from such a material, the above-mentioned effects are more easily achieved. In this embodiment, instead of the rubber material, a member such as a leaf spring may be used as the elastic material.

[0033] <Variation 1> FIG. 5 is a diagram showing a main part (coating device main part 51) of a coating device 50 serving as Modification 1, and corresponds to FIG. 3(B) in the present embodiment. As shown in FIG. 5, in the first modification, a cam 67 serving as an adjustment mechanism is used as a limiting member instead of the stopper 66 in the present embodiment. The cam 67 as a limiting member is a cam that can adjust the distance that the pressure roller 57 can move in the separating direction (upward) according to the thickness (sheet thickness) of the sheet P entering the nip between the application roller 52 and the pressure roller 57. Specifically, cam 67 (limiting member) as an adjustment mechanism is installed so that its cam surface can come into contact with the upper part of pressure arm 58, and limits the movement in the separating direction (upward direction) of pressure arm 58. In addition, cam 67 (limiting member) has a rotation shaft connected to second cam motor 73, and is configured so that the cam angle (attitude in the rotation direction) can be varied by control of second cam motor 73 by control unit 70. When the sheet P is not conveyed to the nip, there is a gap between the cam 67 and the pressure arm 58 (positioned at the rotation position indicated by the dashed line). When the sheet P enters the nip and the pressure roller 57 (pressure arm 58) is raised by the thickness of the sheet P against the bias of the tension spring 60, the cam 67 comes into contact with the pressure arm 58 (as shown in FIG. 5). Here, the cam angle of the cam 67 is adjusted according to the thickness of the sheet P entering the nip. That is, the gap between the cam 67 and the pressure arm 58 is adjusted when the sheet P is not conveyed to the nip. Specifically, when the sheet P is thick, the second cam motor 73 is controlled so that the above-mentioned gap becomes larger compared to when the sheet P is thin. As a result, regardless of the thickness of the sheet P, it is possible to reduce coating unevenness (variation) of the coating liquid G applied to the sheet P without causing a transport failure of the sheet P.

[0034] In particular, in the first modification, as shown in Fig. 5, a sheet thickness detection sensor 75 serving as a detection means for directly detecting the thickness of the sheet P entering the nip is provided in the sheet conveying path upstream of the nip. As such a sheet thickness detection sensor 75, for example, a distance measurement sensor can be used. When the thickness of the sheet P detected by the sheet thickness detection sensor 75 (detection means) is thick, the cam angle of the cam 67 is adjusted so that the distance that the pressure roller 57 can move in the separation direction is greater (so that the gap between the cam 67 and the pressure arm 58 when not being conveyed is greater) compared to when the thickness of the sheet P is thin. The detection means may indirectly detect the thickness of the sheet P entering the nip. For example, an operation display panel 40 (see FIG. 1) installed on the exterior of the image forming system 100 may be used as such a detection means. Specifically, the thickness of the sheet P entering the nip can be indirectly detected from information about the sheet P input by the user through the operation display panel 40. In addition, instead of the cam 67, the adjustment mechanism may be provided with a contact member that can contact the pressure arm 58, and a member such as a solenoid that moves the contact member so as to change the gap between the pressure arm 58 and the contact member.

[0035] <Variation 2> FIG. 6 is a diagram showing a main part (coating device main part 51) of a coating device 50 serving as Modification 2, and corresponds to FIGS. 3(A) and (B) in the present embodiment. In the coating device 50 in the second modification, the configurations of the pressure mechanisms 61 to 64 that press the pressure roller 57 against the coating roller 52 are different from those in the present embodiment. As shown in FIG. 6, the pressure mechanism in the second modification is composed of a first pressure arm 61, a second pressure arm 62, a pressure cam 63, a compression spring 64, and the like. The first pressure arm 61 is held by the main body housing so as to be rotatable around a support shaft 61a, and rotatably holds the pressure roller 57. The second pressure arm 62 is held by the main body housing so as to be rotatable around the support shaft 61a of the first pressure arm 61, independently of the rotation of the first pressure arm 61. The second pressure arm 62 is provided with a compression spring 64 (one end connected to the first pressure arm 61, and the other end connected to the second pressure arm 62) that biases the first pressure arm 61 together with the pressure roller 57 toward the application roller 52. The pressure cam 63 has a cam surface in contact with the upper part of the second pressure arm 62, and is driven to rotate by a cam motor 71 to change the cam angle, thereby moving the pressure roller 57 up and down together with the first and second pressure arms 61 and 62. When the application process is performed, the pressure roller 57 is moved by the pressure mechanisms 61 to 63 to the contact position (a position in contact with the application roller 52) shown in Fig. 6(A). On the other hand, when the application process is not performed, the pressure roller 57 is moved by the pressure mechanisms 61 to 63 to the separation position (a position away from the application roller 52). Here, the coating device 50 in the second modification is also provided with a stopper 66 as a limiting member, similar to that of the present embodiment. More specifically, in the second modification, as shown in Fig. 6, the stopper 66 is provided on the opposing surface of the first pressure arm 61 (the opposing surface opposing the second pressure arm 62). When the sheet P enters the nip between the coating roller 52 and the pressure roller 57, the stopper 66 indirectly comes into contact with the pressure roller 57 (comes into contact with the second pressure arm 62) as shown in Fig. 6(B), and functions as a limiting member that limits the movement of the pressure roller 57 in the separating direction relative to the coating roller 52. As a result, uneven application (variation) of the coating liquid G applied to the sheet P can be reduced without causing a transport failure of the sheet P.

[0036] <Modification 3> FIG. 7 is a diagram showing a main part (coating device main part 51) of a coating device 50 serving as Modification 3, and corresponds to FIG. 3(B) in the present embodiment. 7, the pressure mechanism in the third modification is also composed of a first pressure arm 61, a second pressure arm 62, a pressure cam 63, a compression spring 64, etc., similar to the pressure mechanism in the second modification. In the third modification, a cam 67 is used as a limiting member instead of the stopper 66 in the second modification. The cam 67 as a limiting member is a cam that can adjust the distance that the pressure roller 57 can move in the separating direction (upward) according to the thickness of the sheet P entering the nip between the application roller 52 and the pressure roller 57. Specifically, the cam 67 (limiting member) is installed so that its cam surface can come into contact with the upper part of the first pressure arm 61, and limits the movement in the separating direction (upward direction) of the first pressure arm 61. In addition, the cam 67 (limiting member) has a rotation shaft connected to the second cam motor 73, and is configured so that the cam angle (attitude in the rotation direction) can be varied by the control of the second cam motor 73 by the control unit 70. When the sheet P is not conveyed to the nip, there is a gap between the cam 67 and the first pressure arm 61 (positioned at the rotation position indicated by the dashed line). When the sheet P enters the nip and the pressure roller 57 (first pressure arm 61) is raised by the thickness of the sheet P against the bias of the compression spring 64, the cam 67 comes into contact with the first pressure arm 61 (as shown in FIG. 7). Here, like in the first modification, the cam angle of the cam 67 in the third modification is adjusted according to the thickness of the sheet P entering the nip (detection result of the sheet thickness detection sensor 75 as detection means). As a result, regardless of the thickness of the sheet P, it is possible to reduce coating unevenness (variation) of the coating liquid G applied to the sheet P without causing a transport failure of the sheet P.

[0037] <Variation 4> FIG. 8 is a diagram showing a main part (coating device main part 51) of a coating device 50 serving as Modification 4, and corresponds to FIG. 6(A) in Modification 2. As shown in FIG. 8 to 10, coating device 50 in variant 4 differs from that in variant 2 shown in FIG. 6 mainly in that it is provided with a pressure roller 68 as a pressure member, a first adjustment bolt 76 as a gap adjustment mechanism, a second adjustment bolt 77 as a nip pressure adjustment mechanism, and an arm member 74 and a tension spring 79 as a pressure reduction mechanism. 8 to 11, the pressure roller 68 is held by the first pressure arm 61 (pressure arm) and functions as a pressure member that comes into contact with the pressure roller 57 (pressure rotating body). The first pressure arm 61 (pressure mechanisms 61 to 64) is configured to urge the pressure roller 57 against the application roller 52 (application rotating body) via the pressure roller 68 (pressure member). Specifically, the pressure roller 68 is rotatably held by the first pressure arm 61, and configured to follow the movement of the first pressure arm 61. The pressure roller 68 is formed so that its roller diameter is sufficiently larger than that of the pressure roller 57, and its rigidity is sufficiently higher than that of the pressure roller 57. The pressure mechanisms 61 to 64 are configured similarly to that shown in FIG. 6 described in the second modified example, except that they hold the pressure roller 68 instead of the pressure roller 57. 10, the pressure mechanisms 61-64 are installed at both ends in the longitudinal direction (both ends in the direction of the rotation axis), and the longitudinal center of the pressure roller 68 is easily bent, but the pressure roller 68 is made larger in diameter and has higher rigidity, so that such bending is less likely to occur. Therefore, the pressure roller 68 is uniformly pressed against the pressure roller 57 along the longitudinal direction, which reduces uneven application caused by uneven nip pressure between the pressure roller 57 and the application roller 52, and reduces transport defects such as skew of the sheet P.

[0038] As shown in FIG. 9, the coating apparatus 50 in the fourth modification is provided with a first adjustment bolt 76 as a gap adjustment mechanism. This first adjustment bolt 76 functions as a gap adjustment mechanism that can adjust a predetermined gap formed between the stopper 66 (restricting member) and the second pressure arm 62 (pressure arm) when the sheet P does not enter the nip between the pressure roller 57 and the application roller 52. More specifically, as shown in Fig. 9, a female thread is formed in the second pressure arm 62 at a position facing the stopper 66, and a first adjustment bolt 76 is screwed into the female thread. With this configuration, as shown in Figs. 9(A) and (B), by varying the amount of tightening of the first adjustment bolt 76, it is possible to adjust the distance between the screw tip of the first adjustment bolt 76 and the stopper 66 (the gap between the second pressure arm 62 and the stopper 66). When the sheet P enters the nip, the stopper 66 comes into contact with the second pressure arm 62, thereby restricting the movement of the pressure roller 57 in the separating direction. However, since the gap between the stopper 66 and the second pressure arm 62 is formed by the interaction of many parts, there is a possibility that the gap between the stopper 66 and the second pressure arm 62 cannot be set to a target value due to an accumulation of variations in precision of those parts, and the stopper 66 will no longer function as a restricting member. In contrast, in the fourth variant, a first adjustment bolt 76 is provided as a gap adjustment mechanism, which makes it possible to adjust the gap between the stopper 66 and the second pressure arm 62 to a desired value, thereby preventing the occurrence of such a problem.

[0039] As shown in FIGS. 9 and 10, the coating device 50 in the fourth modified example is provided with a second adjustment bolt 77 as a nip adjustment mechanism. The second adjustment bolts 77 function as nip pressure adjustment mechanisms capable of adjusting the pressure (nip pressure) at the nip between the pressure roller 57 and the application roller 52, and are provided in multiple locations spaced apart in the longitudinal direction (the direction perpendicular to the plane of the paper in FIG. 9, and the left-right direction in FIG. 10). In this embodiment, as shown in FIG. 10, second adjustment bolts 77 (nip pressure adjustment mechanisms) are provided at both ends in the longitudinal direction. 9 and 10, a female screw portion is formed in the first pressure arm 61 at a position facing the compression spring 64, and a second adjustment bolt 77 is screwed into the female screw portion. A receiving plate 78 is provided at the screw tip of the second adjustment bolt 77, and one end of the compression spring 64 is connected to the receiving plate 78. With this configuration, as shown in FIGS. 9(A) and 9(B), by varying the amount of tightening of the second adjustment bolt 77, the usable length of the compression spring 64 changes, and the nip pressure between the pressure roller 57 and the application roller 52 can be adjusted. The nip pressure between the pressure roller 57 and the application roller 52 may have a deviation (pressure difference) in the longitudinal direction due to variation in the part precision of related parts. If such a deviation in the nip pressure occurs, then uneven application in the longitudinal direction and conveyance defects such as skew of the sheet P occur. In contrast, in the fourth modification, second adjustment bolts 77 serving as a nip pressure adjustment mechanism are provided at both longitudinal ends, making it possible to adjust the balance of the nip pressure in the longitudinal direction between pressure roller 57 and application roller 52, thereby preventing the occurrence of such a problem. Furthermore, the second adjustment bolts 77 serving as a nip pressure adjustment mechanism can increase or decrease the overall nip pressure (total pressure) as well as the longitudinal balance of the nip pressure, making it possible to adjust the overall amount of application of application liquid G.

[0040] As shown in FIGS. 9 and 11, the coating device 50 in the fourth modification is provided with an arm member 74 and a tension spring 79 as a pressure reducing mechanism. The arm member 74 and the tension spring 79 function as a pressure reducing mechanism that reduces the contact pressure (nip pressure) between the application roller 52 (application rotor) and the pressure roller 57 (pressure rotor), as well as the contact pressure (nip pressure) between the pressure roller 57 and the pressure roller 68 (pressure member). More specifically, an L-shaped arm member 74 is fixed to the first pressure arm 61. The arm member 74 is formed so that a portion bent into an L shape (bent portion) is located below the shaft portion of the pressure roller 57. Further, one end of a tension spring 79 is connected to the tip portion of the first pressure arm 61 remote from the support shaft 61a. The other end of the tension spring 79 is connected to the main body housing. 9, under normal circumstances, the bent portion of arm member 74 is in a position spaced apart from the shaft portion of pressure roller 57. At this time, application roller 52 and pressure roller 57 come into contact with each other at a target nip pressure, and pressure roller 57 and hold-down roller 68 come into contact with each other at a target nip pressure. On the other hand, when the nip pressure is reduced, as shown in FIG. 11, the cam motor 71 drives the pressure cam 63 to rotate around the cam shaft 63a by a predetermined angle, causing the second pressure arm 62 to rotate (lift) counterclockwise around the support shaft 61a, and the compression spring 64 is released, causing the first pressure arm 61 to rotate (lift) counterclockwise around the support shaft 61a. This reduces the nip pressure between the pressure roller 57 and the press roller 68. Furthermore, the bent portion of the arm member 74 installed on the first pressure arm 61 pushes the shaft portion of the pressure roller 57 upward, causing the pressure roller 57 to move upward, thereby reducing the nip pressure between the application roller 68 and the pressure roller 57. This reduction in the nip pressure is performed to remove the sheet P when the sheet P becomes stuck (jammed) between the pressure roller 57 and the application roller 52 (nip). Moreover, the operation of the pressure reduction mechanisms 74, 79 in the event of such a jam can be performed by controlling the driving of the cam motor 71 when the sheet detection sensor detects a jam of the sheet P. By providing the pressure reduction mechanisms 74, 79 in this way, the user can easily clear the jam. The nip pressure reduction by the pressure reduction mechanisms 74 and 79 can be performed not only when a jam occurs, but also when the sheet P is not interposed in the nip between the application roller 68 and the pressure roller 57 during normal paper passing. That is, when the sheet P is passing through the nip, the nip pressure reduction is not performed as shown in FIG. 9, and when the sheet P is not passing through the nip, the nip pressure reduction is performed as shown in FIG. 11. This can reduce the inconvenience that the pressure roller 57 and the application roller 52 are in contact for a long time, the application liquid G remains in the nip, the water evaporates from the application liquid G, and the viscosity increases, causing jams of the sheet P and uneven application due to the viscosity increased application liquid G. While the nip pressure reduction by the pressure reduction mechanisms 74 and 79 is being performed, the application liquid G remaining in the nip is returned to the storage section 55.

[0041] As described above, the coating device 50 (image forming system 100) in this embodiment is provided with the coating roller 52 (coating rotary body) that applies the coating liquid G to the sheet P, and the pressure roller 57 (pressure roller) that forms a nip between the coating roller 52. Furthermore, there is provided a stopper 66 (limiting member) that directly or indirectly contacts the pressure roller 57 when the sheet P enters the nip between the coating roller 52 and the pressure roller 57, thereby limiting the movement of the pressure roller 57 in the direction away from the coating roller 52. This makes it possible to reduce variation in the amount of coating liquid G applied to the sheet P.

[0042] In this embodiment, the present invention is applied to the coating device 50 as a pretreatment device of the inkjet printer 1, but the application of the present invention is not limited to this, and the present invention can be applied to all coating devices that apply a coating liquid to a sheet. In the present embodiment, the application roller 52 is used as the application rotating body, and the pressure roller 57 is used as the pressure rotating body. However, the application rotating body and the pressure rotating body are not limited to these, and for example, a application belt (belt member) supported by multiple rollers can be used as the application rotating body, and a pressure belt (belt member) supported by multiple rollers can be used as the pressure rotating body. In the present embodiment, the positional relationship between the application roller 52 and the pressure roller 57 in the application device 50 shown in FIG. 1 can also be interchanged. Even in such cases, the same effects as those of this embodiment can be obtained.

[0043] It is clear that the present invention is not limited to the present embodiment, and that the present embodiment may be modified as appropriate within the scope of the technical concept of the present invention in addition to the modifications suggested in the present embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to the present embodiment, and may be any number, position, shape, etc. suitable for implementing the present invention.

[0044] In this specification, the term "sheet" is not limited to paper, but is defined to include all sheet-like recording media, such as coated paper, label paper, OHP sheets, metal sheets, and the like.

[0045] 1 Image forming device (inkjet printer), 40 Operation display panel, 50 Coating equipment, 51 Coating device main part, 52 application roller (application rotating body), 53 Intermediate roller (measuring roller), 54 Pumping roller, 55 storage section (supply pan), 57 Pressure roller (pressure rotating body), 58 Pressure arm, 66 Stopper (restriction member), 67 Cam (adjustment mechanism, limiting member), 75 sheet thickness detection sensor (detection means), 80 Paper feeder, 85 Drying equipment; 90 Paper ejection device, 100 Image forming system, G coating liquid (liquid), P sheet (subject to be coated). [Prior art documents] [Patent documents]

[0046] [Patent Document 1] JP 2013-91260 A

Claims

1. A coating rotor that applies a coating liquid to a sheet; a pressurizing rotor that forms a nip between itself and the coating rotor; a pressure arm that biases the pressure rotating body toward the application rotating body; a limiting member that indirectly contacts the pressurizing rotor via the pressurizing arm when the sheet enters the nip, and limits movement of the pressurizing rotor in a direction away from the coating rotor; Equipped with The coating device according to claim 1, wherein the restricting member does not indirectly contact the pressure rotating body via the pressure arm when the sheet does not enter the nip.

2. A coating rotor that applies a coating liquid to a sheet; a pressurizing rotor that forms a nip between itself and the coating rotor; a limiting member that directly or indirectly comes into contact with the pressurizing rotator when the sheet enters the nip, and limits movement of the pressurizing rotator in a direction away from the coating rotator; a pressure arm that biases the pressure rotating body toward the application rotating body; Equipped with the limiting member abuts against the pressure arm when the sheet enters the nip to limit the movement of the pressure rotating body in the separating direction, a coating device having a predetermined gap between the restricting member and the pressure arm when no sheet has entered the nip;

3. 3. The coating apparatus according to claim 2, further comprising a gap adjustment mechanism capable of adjusting the predetermined gap.

4. A coating rotor that applies a coating liquid to a sheet; a pressurizing rotor that forms a nip between itself and the coating rotor; a pressure arm that biases the pressure rotating body toward the application rotating body; a limiting member that indirectly contacts the pressurizing rotor via the pressurizing arm when the sheet enters the nip, and limits movement of the pressurizing rotor in a direction away from the coating rotor; Equipped with The application device, wherein the limiting member is made of an elastic material.

5. 5. The coating device according to claim 4, wherein the elastic material is a rubber material having a Shore A hardness in the range of 30 to 70.

6. A coating rotor that applies a coating liquid to a sheet; a pressurizing rotor that forms a nip between itself and the coating rotor; a pressure arm that biases the pressure rotating body toward the application rotating body; a limiting member that indirectly contacts the pressurizing rotor via the pressurizing arm when the sheet enters the nip, and limits movement of the pressurizing rotor in a direction away from the coating rotor; Equipped with The coating device according to claim 1, wherein the limiting member is an adjustment mechanism that can adjust the distance by which the pressure rotating body can move in the separation direction in accordance with the thickness of the sheet entering the nip.

7. A detection means for directly or indirectly detecting the thickness of a sheet entering the nip is provided, The coating device according to claim 6, characterized in that the adjustment mechanism increases the distance that the pressure rotating body can move in the separation direction when the thickness of the sheet detected by the detection means is thick, compared to when the thickness of the sheet is thin.

8. a pressing member held by the pressure arm and in contact with the pressure rotating body; 8. The coating apparatus according to claim 1, wherein the pressure arm urges the pressure rotating body against the coating rotating body via the pressing member.

9. 9. The coating apparatus according to claim 8, further comprising a pressure reducing mechanism for reducing a contact pressure between said coating rotor and said pressure rotating body and between said pressure rotating body and said pressing member.

10. 10. The coating apparatus according to claim 1, further comprising a plurality of nip pressure adjusting mechanisms each capable of adjusting a pressure at the nip, the nip pressure adjusting mechanisms being provided at positions spaced apart from each other in the longitudinal direction.

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

Images