Image forming system

Abstract

Compared to a case where only one end of the guide section of the medium moves toward or away from the intermediate transfer body, an image forming system is obtained in which the occurrence of image quality defects is suppressed. [Solution] The image forming system includes: an endless intermediate transfer body that is wrapped around multiple rolls and moves in a circumferential direction to transport a toner image that has been primarily transferred to its outer surface; a transfer rotating body that rotates and transfers the toner image of the intermediate transfer body to a medium at a secondary transfer position opposite to the intermediate transfer body; a counter rotating body that rotates and faces the transfer rotating body with the intermediate transfer body in between, forming a potential difference between itself and the transfer rotating body; a guide part provided upstream of the transport direction of the medium relative to the secondary transfer position to guide the medium to the secondary transfer position; and a moving part that, depending on the type of medium, moves the entire medium contact area of ​​the guide part toward or away from the intermediate transfer body while maintaining an orientation that intersects a line connecting the center of the transfer rotating body and the center of the counter rotating body.

Description

Technical Field

[0001] The present invention relates to an image forming system.

Background Art

[0002] The following Patent Document 1 discloses an image forming apparatus including an intermediate transfer belt, a secondary transfer member, an endless secondary transfer belt, a facing member, and contact width changing means. The intermediate transfer belt is stretched over a plurality of rollers and conveys a toner image on its outer peripheral surface. The secondary transfer member secondarily transfers the toner image on the intermediate transfer belt to a recording medium at a secondary transfer position facing the intermediate transfer belt. The secondary transfer belt is wound around the secondary transfer member and circulates while being sandwiched between the secondary transfer member and the intermediate transfer belt as the secondary transfer member rotates. The facing member is disposed to face the secondary transfer member so as to contact the inner peripheral surface of the intermediate transfer belt and sandwich the secondary transfer belt at the secondary transfer position. The contact width changing means changes the contact width of a contact area formed by surface contact between a part of the peripheral surface of the intermediate transfer belt and a part of the peripheral surface of the secondary transfer belt at the secondary transfer position based on the paper attribute information of the recording medium. Specifically, the contact width changing means changes the contact width of the contact area between a predetermined first contact width and a second contact width having a large increase amount of the contact width on the upstream side in the paper conveyance direction.

[0003] The following Patent Document 2 discloses an image forming apparatus including an image carrier, a transfer means, a recording material conveyance means, and a recording material guiding means. The image carrier carries a visible image formed by a charged coloring material. The transfer means transfers the visible image on the image carrier to a recording material. The recording material conveyance means conveys the recording material to a transfer site between the transfer means and the image carrier. The recording material guiding means is provided in a conveyance path between the recording material conveyance means and the transfer site and regulates the intrusion posture of the recording material into the transfer site. The recording material guiding means includes a movable guiding member disposed on the image carrier side and at least a downstream portion in the conveyance direction of the recording material being movable in the direction of the image carrier.

[0004] Patent Document 3 discloses an image forming apparatus comprising one or more image holders, a thin-walled intermediate transfer body, a primary transfer member, a secondary transfer member, a surface preparation member, and a tension adjustment member. One or more image holders form and hold color component images using color component toners. The intermediate transfer body faces the image holders and is circulated and transported by being suspended across a plurality of tension members, temporarily holding the color component images formed by the image holders before transferring them to a recording material. The primary transfer member is provided on the back surface of the intermediate transfer body facing the image holders, and transfers the color component images held by the image holders to the intermediate transfer body by forming a transfer electric field in the primary transfer area between the primary transfer body and the image holders. The secondary transfer member is positioned in contact with the surface of the intermediate transfer body, facing the tension members provided on the back surface of the intermediate transfer body, and transfers the color component images transferred to the intermediate transfer body by the primary transfer member to a recording material by forming a transfer electric field in the secondary transfer area between the tension members. The surface preparation member is positioned upstream of the secondary transfer member in the transport direction of the intermediate transfer body and is in contact with the back surface of the intermediate transfer body. It is provided to be movable forward and backward along a direction intersecting the surface direction of the intermediate transfer body, and forms the transport trajectory surface of the intermediate transfer body leading to the secondary transfer area. The tension adjustment member adjusts the tension of the intermediate transfer body to counteract the loosening of the intermediate transfer body caused by the surface preparation member moving from a predetermined position. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-134614 [Patent Document 2] Japanese Patent Application Publication No. 11-143254 [Patent Document 3] Japanese Patent Publication No. 2014-191100 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] The present invention aims to provide an image forming system that suppresses the occurrence of image quality defects compared to a system in which only one end of the guide portion of the medium moves toward or away from the intermediate transfer body. [Means for solving the problem]

[0007] The image forming system according to the first embodiment includes: an endless intermediate transfer body that is wrapped around a plurality of rolls and moves in a circumferential direction to transport a toner image that has been primary transferred to its outer surface; a transfer rotating body that rotates and comes into contact with the intermediate transfer body and transfers the toner image of the intermediate transfer body to a medium at a secondary transfer position opposite to the intermediate transfer body; a counter rotating body that rotates and faces the transfer rotating body with the intermediate transfer body in between, forming a potential difference between itself and the transfer rotating body; a guide part provided upstream of the transport direction of the medium with respect to the secondary transfer position to guide the medium to the secondary transfer position; and a moving part that, depending on the type of medium, moves the entire medium contact portion of the guide part toward or toward the intermediate transfer body while maintaining an orientation in a direction that intersects a line connecting the center of the transfer rotating body and the center of the counter rotating body.

[0008] The image forming system according to the second embodiment is the image forming system according to the first embodiment, wherein when the medium is a medium or film medium thicker than a predetermined thickness, the moving part moves the entire medium contact portion of the guide part in a direction closer to the intermediate transfer body than when the medium is of the predetermined thickness.

[0009] The image forming system according to the third embodiment is the image forming system according to the first embodiment, wherein when the medium is a medium with a surface smoother than a predetermined smoothness, the moving part moves the entire medium contact portion of the guide part in a direction away from the intermediate transfer body compared to when the medium has the predetermined smoothness.

[0010] The image forming system according to the fourth embodiment is the image forming system according to the first embodiment, wherein the moving part moves the entire medium contact portion of the guide part toward or toward the intermediate transfer body in accordance with the secondary transfer voltage applied to the transfer rotating body or the opposing rotating body.

[0011] The image forming system according to the fifth embodiment is the image forming system according to the fourth embodiment, wherein when the secondary transfer voltage is higher than the reference voltage, the moving part moves the entire medium contact portion of the guide part in a direction closer to the intermediate transfer body than when the secondary transfer voltage is less than or equal to the reference voltage.

[0012] The image forming system according to the sixth embodiment is an image forming system according to the first embodiment, wherein a rotating member that contacts the inside of the intermediate transfer body is provided downstream in the circumferential direction of the intermediate transfer body from the primary transfer position where a toner image is transferred to the intermediate transfer body, and upstream in the circumferential direction of the intermediate transfer body from the opposing rotating body, and the contact point where the medium guided by the guide comes into contact with the intermediate transfer body is downstream of the rotating member in the circumferential direction of the intermediate transfer body.

[0013] The image forming system according to the seventh embodiment is the image forming system according to the first embodiment, wherein the transport direction of the medium guided by the guide is in a direction along a virtual tangent to the transfer rotating body that is perpendicular to the line connecting the center of the transfer rotating body and the center of the opposing rotating body.

[0014] The image forming system according to the eighth embodiment is the image forming system according to the seventh embodiment, wherein the media contact portion of the guide portion is planar in a side view.

[0015] The image forming system according to the ninth embodiment is configured such that, when the guide is moved by the moving part toward the intermediate transfer body and when it is moved toward the intermediate transfer body, the angle between the virtual tangent of the transfer rotation body, which is perpendicular to the line connecting the center of the transfer rotation body and the center of the opposing rotation body, and the media contact portion of the guide is within ±4 degrees of the angle before the movement.

[0016] The image forming system according to the tenth embodiment is an image forming system according to the first embodiment, comprising: an adjustment roll provided upstream of the guide in the medium transport direction for adjusting the transport timing of the medium; and a second moving unit that moves the adjustment roll toward or toward the intermediate transfer body according to the movement position of the guide. [Effects of the Invention]

[0017] According to the image forming system of the first embodiment, the occurrence of image quality defects is suppressed compared to the case in which only one end of the guide portion of the medium is moved in a direction toward or away from the intermediate transfer body.

[0018] According to the image forming system of the second embodiment, the occurrence of image quality defects is suppressed compared to the case where the position of the guide portion does not change when the medium is thicker than a predetermined thickness or when it is a film medium.

[0019] According to the image forming system of the third embodiment, the occurrence of image quality defects due to toner scattering is suppressed compared to the case where the position of the guide portion does not change when the medium has a surface smoother than a predetermined smoothness.

[0020] According to the image forming system of the fourth embodiment, the occurrence of image quality defects is suppressed compared to the case where the position of the guide does not change by changing the secondary transfer voltage.

[0021] According to the image forming system according to the fifth aspect, the occurrence of image quality defects is suppressed as compared with the case where the position of the guide portion does not change when the secondary transfer voltage is higher than the reference voltage.

[0022] According to the image forming system according to the sixth aspect, the occurrence of scratches on the medium is suppressed as compared with the case where the contact point where the medium guided by the guide portion contacts the intermediate transfer member is downstream of the primary transfer position in the circumferential direction of the intermediate transfer member and upstream of the rotating member.

[0023] According to the image forming system according to the seventh aspect, the occurrence of scratches on the medium is suppressed as compared with the case where the conveyance direction of the medium guided by the guide portion intersects the virtual tangent line of the transfer rotating body orthogonal to the line connecting the center of the transfer rotating body and the center of the counter-rotating body.

[0024] According to the image forming system according to the eighth aspect, the occurrence of scratches on the medium is suppressed as compared with the case where the medium contact portion in the guide portion is curved or bent.

[0025] According to the image forming system according to the ninth aspect, the occurrence of scratches on the medium is suppressed as compared with the case where the angle between the virtual tangent line and the medium contact portion in the guide portion changes when the guide portion moves in the direction approaching the intermediate transfer member and when it moves away from the intermediate transfer member.

[0026] According to the image forming system according to the tenth aspect, the occurrence of scratches on the medium is suppressed as compared with the case where the position of the position adjustment roll is fixed when the guide portion moves.

Brief Description of Drawings

[0027] [Figure 1] It is a schematic diagram showing a configuration of the image forming system according to the first embodiment as viewed from the front side. [Figure 2] It is a configuration diagram showing the moving direction of the guide portion in the secondary transfer portion of the image forming system according to the first embodiment. [Figure 3]This is a configuration diagram showing the state in which the guide portion in the secondary transfer section of the image forming system according to the first embodiment has been moved to a second position close to the intermediate transfer belt. [Figure 4] This is a configuration diagram showing the movement direction of the guide portion in the secondary transfer section of the image forming system according to the second embodiment. [Figure 5] This is a configuration diagram illustrating the positional relationship between the guide unit and the register roll in the secondary transfer unit of the image forming system according to the second embodiment. [Figure 6] This is a configuration diagram showing the movement direction of the guide in the secondary transfer section of the image forming system according to the third embodiment. [Figure 7] This is a configuration diagram showing the state in which the guide portion in the secondary transfer section of the image forming system according to the third embodiment has been moved to a second position close to the intermediate transfer belt. [Figure 8] This graph shows the relationship between the height of the guide section into which the paper enters and the amount of whitening caused by pre-discharge in the image forming system according to the third embodiment. [Figure 9] This is a configuration diagram showing the movement direction of the guide in the secondary transfer section of the image forming system according to the fourth embodiment. [Figure 10] This is a configuration diagram showing the state in which the guide portion in the secondary transfer section of the image forming system according to the fourth embodiment has been moved to a second position close to the intermediate transfer belt. [Modes for carrying out the invention]

[0028] The following describes embodiments for carrying out the present invention. In the following description, the direction indicated by arrow H in the drawings is the vertical direction, and the direction indicated by arrow W is the horizontal direction, which is the width direction of the device.

[0029] [First Embodiment] The image forming system according to the first embodiment will be described below.

[0030] <Overall configuration of the image forming system> Figure 1 is a schematic diagram showing the configuration of the image forming system 10 according to the first embodiment, as viewed from the front. As shown in Figure 1, the image forming system 10 includes an image forming unit 12 that forms an image on paper P using an electrophotographic method, a transport device 50 that transports the paper P, and a control unit 90 that controls the operation of each part of the image forming system 10. Paper P is an example of a medium.

[0031] (Conveyor device) As shown in Figure 1, the transport device 50 includes a storage section 51 for storing paper P, and a plurality of transport rolls 52 and 53 for transporting paper P from the storage section 51 toward the secondary transfer position NT. The transport device 50 also includes a guide section 56 positioned upstream of the transport direction of paper P relative to the secondary transfer position NT, and a register roll 54 positioned upstream of the guide section 56 toward the transport direction of paper P. The register roll 54 adjusts the timing of the transport of paper P to the secondary transfer position NT. The guide section 56 guides paper P toward the secondary transfer position NT downstream of the register roll 54 in the transport direction. Furthermore, the transport device 50 includes a transport belt 58 for transporting paper P from the secondary transfer position NT toward the fixing device 40, which will be described later.

[0032] (Image forming unit) The image forming unit 12 includes a toner image forming unit 20 that forms a toner image, a transfer device 30 that transfers the toner image formed by the toner image forming unit 20 to the paper P, and a fixing device 40 that heats and pressurizes the toner image transferred to the paper P to fix it to the paper P.

[0033] Multiple toner image forming units 20 are provided to form toner images for each color. As an example, a total of four toner image forming units 20 are provided for yellow (Y), magenta (M), cyan (C), and black (K). These toner image forming units 20 for each color are arranged in the order of yellow (Y), magenta (M), cyan (C), and black (K), from the upstream side to the downstream side in the transport direction of the intermediate transfer belt 31, which will be described later.

[0034] Figure 1 shows (Y), (M), (C), and (K) to indicate the component parts corresponding to each of the above colors. In this specification, the parentheses around (Y), (M), (C), and (K) may be omitted, and they may be written as Y, M, C, and K.

[0035] [Toner image forming unit] Each toner image forming unit 20 is basically configured similarly, except for the toner used. Specifically, each toner image forming unit 20 includes a photoreceptor drum 21, a charger 22, an exposure device 23, a developer device 24, and a cleaning device 25. The photoreceptor drum 21 has a photosensitive layer on its surface and rotates in the clockwise direction indicated by the arrow. The charger 22 charges the photoreceptor drum 21. The exposure device 23 exposes the photoreceptor drum 21, which has been charged by the charger 22, to form an electrostatic latent image on the photoreceptor drum 21. The developer device 24 develops the electrostatic latent image formed on the photoreceptor drum 21 by the exposure device 23 to form a toner image. The cleaning device 25 is equipped with a blade 25A, which removes toner remaining on the surface of the photoreceptor drum 21 after the transfer of the toner image to the transfer device 30. In Figure 1, the components of the toner image forming section 20 for each color are the same except for the toner, so the illustrations of (Y), (M), (C), and (K) are omitted.

[0036] The charger 22, for example, negatively charges the surface (photosensitive layer) of the photoreceptor drum 21. The negatively charged surface of the photoreceptor drum 21 exhibits positive polarity in the area irradiated with exposure light L by the exposure device 23, and an electrostatic latent image is formed on the surface of the photoreceptor drum 21. Then, toner that has been negatively frictionally charged in the developing device 24 adheres to the positively polarized electrostatic latent image, and the electrostatic latent image is developed. In this way, a toner image is formed on the surface (outer surface) of the photoreceptor drum 21. The blade 25A contacts the surface of the photoreceptor drum 21 and scrapes off the toner remaining on the surface of the photoreceptor drum 21.

[0037] [Transfer device] The transfer device 30 comprises an intermediate transfer belt 31, a primary transfer roll 33, and a secondary transfer section 34. The intermediate transfer belt 31 is an example of an intermediate transfer body. The transfer device 30 performs primary transfer by superimposing the toner images of each color photoreceptor drum 21 onto the intermediate transfer belt 31, and then secondary transfers the superimposed toner images onto the paper P at the secondary transfer position NT. The secondary transfer section 34 is It is equipped with a secondary transfer belt 36.

[0038] As shown in Figure 1, the intermediate transfer belt 31 is endless and its orientation is determined by being wound around the drive roll 32D, tensioning roll 32T, pre-roll 70, and inner roll 32B. The drive roll 32D, tensioning roll 32T, pre-roll 70, and inner roll 32B are examples of multiple rolls and contact the inside of the endless intermediate transfer belt 31. The inner roll 32B is an example of a transfer rotating body. The pre-roll 70 is an example of a rotating member. As an example, the intermediate transfer belt 31 is positioned in an inverted obtuse triangle shape that is long in the width direction of the device when viewed from the front. Note that other rolls may be provided around which the intermediate transfer belt 31 is wound.

[0039] The drive roll 32D rotates the intermediate transfer belt 31 in the direction of arrow A using power from a motor (not shown). By rotating in the direction of arrow A, the intermediate transfer belt 31 transports the toner image that has been primary transferred to the outer surface to the secondary transfer position NT. As an example, the drive roll 32D is positioned upstream of the four primary transfer rolls 33 in the rotational direction of the intermediate transfer belt 31. The tension-applying roll 32T applies tension to the intermediate transfer belt 31.

[0040] The pre-roll 70 is positioned downstream of the tension-applying roll 32T and at the primary transfer position T in the circumferential direction of the intermediate transfer belt 31, and upstream of the inner roll 32B. The pre-roll 70 contacts the inside of the intermediate transfer belt 31 upstream of the secondary transfer position NT. The pre-roll 70 contacts the intermediate transfer belt 31 in such a way that it pushes it outward relative to a straight line (not shown) connecting the tangent to the tension-applying roll 32T and the tangent to the inner roll 32B (see Figure 2). As a result, the pre-roll 70 applies tension to the intermediate transfer belt 31 as it moves toward the secondary transfer position NT, stabilizing its circumferential movement.

[0041] Furthermore, the inner roll 32B is the roll opposite to the secondary transfer roll 60, which will be described later. The upper end of the intermediate transfer belt 31, which is positioned as an inverted obtuse-angled triangle as described above, is wrapped around the inner roll 32B at the obtuse angle of the lower end. The upper edge of this intermediate transfer belt 31, which extends in the width direction of the device in the aforementioned position, is in contact with the photosensitive drums 21 of each color from below.

[0042] A cleaning device 35 for removing toner remaining on the intermediate transfer belt 31 is provided downstream of the secondary transfer position NT in the circumferential direction of the intermediate transfer belt 31 and upstream of the primary transfer position T(K). For example, the cleaning device 35 comprises a cleaning brush 35A, a blade 35B, and a scraper 35C. The cleaning brush 35A rotates while in contact with the surface of the intermediate transfer belt 31, removing toner from the surface of the intermediate transfer belt 31. The blade 35B contacts the intermediate transfer belt 31 and scrapes off toner from the surface of the intermediate transfer belt 31. The scraper 35C contacts the intermediate transfer belt 31 and scrapes off toner from the surface of the intermediate transfer belt 31 that could not be removed by the cleaning brush 35A and the blade 35B.

[0043] As shown in Figure 1, the primary transfer roll 33 is a roll that transfers the toner image from each photoreceptor drum 21 to the intermediate transfer belt 31, and is positioned inside the intermediate transfer belt 31. Each primary transfer roll 33 is positioned opposite the corresponding color photoreceptor drum 21, with the intermediate transfer belt 31 in between. Furthermore, a primary transfer voltage with the opposite polarity to the toner polarity is applied to the primary transfer roll 33 by a power supply unit (not shown). By applying this primary transfer voltage, the toner image formed on the photoreceptor drum 21 is transferred to the intermediate transfer belt 31 at the primary transfer position T between the photoreceptor drum 21 and the primary transfer roll 33.

[0044] As shown in Figures 1 and 2, the secondary transfer unit 34 comprises a secondary transfer belt 36, a secondary transfer roll 60 and a driven roll 61 that support the secondary transfer belt 36 so as to be able to rotate around it. The secondary transfer roll 60 is an example of an opposing rotating body. The secondary transfer unit 34 also comprises an inner roll 32B that faces the secondary transfer roll 60 via an intermediate transfer belt 31 and a secondary transfer belt 36, and a contact roll 64 that supplies power to the inner roll 32B by contacting it (see Figure 2). A power supply device 66 is connected to the contact roll 64 (see Figure 2). As an example, the contact roll 64 rotates in association with the rotation of the inner roll 32B. Although not shown, the secondary transfer roll 60 is grounded. Furthermore, the secondary transfer unit 34 is equipped with a cleaning device 62 that removes toner from the surface of the secondary transfer belt 36 (see Figure 1). In the secondary transfer section 34, a transfer electric field is formed by applying a secondary transfer voltage from the power supply unit 66 to the inner roll 32B via the contact roll 64. This transfer electric field transfers the toner image superimposed on the intermediate transfer belt 31 to the paper P transported between the intermediate transfer belt 31 and the secondary transfer belt 36.

[0045] The secondary transfer belt 36 is endless and is wrapped around the secondary transfer roll 60 and the driven roll 61. The secondary transfer roll 60 is rotationally driven by a motor (not shown). The driven roll 61 moves in conjunction with the circumferential movement of the secondary transfer belt 36.

[0046] The secondary transfer roll 60 is positioned so as to sandwich the intermediate transfer belt 31 and the secondary transfer belt 36 between it and the inner roll 32B, and the secondary transfer belt 36 and the intermediate transfer belt 31 are in contact with a predetermined load. The space between the secondary transfer belt 36 and the intermediate transfer belt 31 in this contact is defined as the secondary transfer position NT. Paper P is supplied to this secondary transfer position NT from the storage unit 51 at a predetermined timing. The secondary transfer belt 36 is moved in a circular motion in the direction of arrow B as the secondary transfer roll 60 is rotated.

[0047] For example, the secondary transfer roll 60 is made of a foamed roll in which a conductive resin is dispersed. For example, the driven roll 61 is made of a metal roll. For example, the inner roll 32B is made of a foamed roll in which a conductive material such as carbon is dispersed.

[0048] For example, when transferring the toner image on the surface of the intermediate transfer belt 31 to the paper P, a negative voltage is applied to the inner roll 32B via the contact roll 64 by the power supply unit 66. This creates a potential difference between the inner roll 32B and the secondary transfer roll 60. In other words, by applying a negative voltage to the inner roll 32B, a secondary transfer voltage (positive voltage) with the opposite polarity to the toner is indirectly applied to the secondary transfer roll 60, which forms the opposing electrode of the inner roll 32B. As a result, the negative electrode toner image is transferred from the intermediate transfer belt 31 to the paper P as it passes through the secondary transfer position NT. As an example, the secondary transfer voltage is determined by the type of paper P and the width in the direction perpendicular to the transport direction of the paper P.

[0049] The cleaning device 62 is a blade that contacts the secondary transfer belt 36 and removes toner adhering to the secondary transfer belt 36.

[0050] [Fusing device] As shown in Figure 1, the fixing device 40 includes a heating roll 40A and a pressure roll 40B that is pressed against the heating roll 40A. The paper P on which the toner image has been transferred passes through the nip between the heating roll 40A and the pressure roll 40B, thereby fixing the toner image to the paper P.

[0051] <Operation of the image forming system> Next, the operation of the image forming system 10 will be described.

[0052] When the image forming system 10 starts operating, the toner image forming units 20 for each color (Y), (M), (C), and (K) form toner images of each color on the surface of the photoreceptor drum 21 through charging, exposure, and development processes. Specifically, the photoreceptor drum 21 is charged by the charger 22 and exposed by the exposure device 23, thereby forming a latent image on the surface of the photoreceptor drum 21. Furthermore, the latent image on the photoreceptor drum 21 is developed with toner by the development device 24. As a result, toner images of each color are formed on the surface of the photoreceptor drum 21 in the toner image forming units 20 for each color.

[0053] In the image forming system 10, a primary transfer voltage is applied to the primary transfer rolls 33 of each color. The drive roll 32D rotates the intermediate transfer belt 31 in the direction of arrow A. As a result, the toner images of each color formed on the photoreceptor drums 21 of each color are superimposed onto the intermediate transfer belt 31 and primary transferred.

[0054] Meanwhile, the transport device 50 transports the paper P stored in the storage unit 51 to the secondary transfer position NT so that the timing coincides with the arrival of the portion of the intermediate transfer belt 31 where the toner images of each color have been primary transferred to the secondary transfer position NT. Then, a secondary transfer voltage is applied to the inner roll 32B, creating a transfer electric field between the inner roll 32B and the secondary transfer roll 60, and the toner images of each color held on the intermediate transfer belt 31 are transferred to the paper P.

[0055] Furthermore, the transport device 50 transports the paper P, onto which the toner images of each color have been transferred, toward the fuser device 40. The fuser device 40 then fixes the toner images of each color onto the paper P as it passes between the heating roll 40A and the pressure roll 40B, forming an image on the paper P. This completes the image formation operation.

[0056] <Configuration for moving the guide unit of the image forming system> Next, we will describe the configuration for moving the guide unit 56, which is a key part of the image forming system 10.

[0057] As shown in Figures 2 and 3, the image forming system 10 includes a guide unit 56 that guides the paper P to the secondary transfer position NT, and a moving unit 80 that moves the guide unit 56 toward or toward the intermediate transfer belt 31.

[0058] (Information Department) As shown in Figures 2 and 3, the guide section 56 includes a pair of plate-like sections 102 and 104 spaced apart on both sides of the paper P that passes through. One plate-like section 102 is located on the side farther from the intermediate transfer belt 31, and the other plate-like section 104 is located on the side closer to the intermediate transfer belt 31. In the first embodiment, one plate-like section 102 is located on the lower side in the vertical direction, and the other plate-like section 104 is located on the upper side in the vertical direction. The paper P is guided to the secondary transfer position NT by passing between the pair of plate-like sections 102 and 104.

[0059] As an example, the plate-like portion 102 comprises a planar portion 102A and a bent portion 102B that is bent away from the plate-like portion 104 from the downstream end of the planar portion 102A. The lower surface of the paper P can come into contact with the planar portion 102A of the plate-like portion 102. The planar portion 102A of the plate-like portion 102 is an example of a media contact area (i.e., a paper contact area) that the paper P comes into contact with. As an example, the plate-like portion 104 is planar, and the upper surface of the paper P can come into contact with the plate-like portion 104. As an example, the planar portion 102A of the plate-like portion 102 and the plate-like portion 104 are arranged parallel to each other.

[0060] The planar portion 102A of the guide section 56, which is the paper contact area, is positioned in a direction that intersects with the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60. For example, the planar portion 102A and the plate-like portion 104 of the plate-like portion 102 are inclined upwards toward the secondary transfer position NT. For example, the angle between the virtual tangent line L2 of the inner roll 32B perpendicular to line L1 and the intermediate virtual extension line L3 along the planar portion 102A and the plate-like portion 104 of the plate-like portion 102 is θ.

[0061] (Moving part) As shown in Figures 2 and 3, the movable part 80 includes a cam 82 that contacts the lower surface (the surface opposite to the plate-shaped part 104) of the planar portion 102A of the plate-shaped part 102, and a motor 84 that rotates the shaft portion 83 of the cam 82. The drive of the motor 84 is controlled by the control unit 90.

[0062] The moving unit 80 moves the entire planar portion 102A of the guide unit 56 relative to the intermediate transfer belt 31 while maintaining its orientation in a direction intersecting line L1, depending on the type of paper P. For example, the pair of plate-like portions 102 and 104 are integrally supported by a frame (not shown). The moving unit 80 moves the pair of plate-like portions 102 and 104 together in the vertical direction (direction of arrow D) by rotating the cam 82. Specifically, by rotating the cam 82, the smaller diameter portion of the cam 82 comes into contact with the plate-like portion 102, thereby moving the guide unit 56 to a first position P1 (see Figure 2) that is far from the intermediate transfer belt 31. Also, by rotating the cam 82, the larger diameter portion of the cam 82 comes into contact with the plate-like portion 102, thereby moving the guide unit 56 to a second position P2 (see Figure 3) that is closer to the intermediate transfer belt 31. In the first embodiment, the moving part 80 moves the guide part 56 to a first position P1 on the lower side in the vertical direction and a second position P2 on the upper side in the vertical direction.

[0063] The type of paper P includes, for example, differences in the thickness of the paper P or differences in the smoothness of the paper P. As an example, when the paper P is thicker than a predetermined thickness, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 closer to the intermediate transfer belt 31 than when the paper P is of the predetermined thickness. In addition, when a film medium is used instead of paper P, the moving unit 80 may move the entire planar portion 102A of the guide unit 56 closer to the intermediate transfer belt 31 than when the paper P is of the predetermined thickness.

[0064] For example, when the paper P has a surface smoother than a predetermined smoothness, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 away from the intermediate transfer belt 31 compared to when the paper has a predetermined smoothness.

[0065] Furthermore, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 toward or toward the intermediate transfer belt 31 in accordance with the secondary transfer voltage.

[0066] As an example, when the secondary transfer voltage is higher than the reference voltage, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 closer to the intermediate transfer belt 31 than when the secondary transfer voltage is below the reference voltage. The reference voltage is preset, for example, according to the thickness of the paper P.

[0067] As an example, the moving part 80 moves the guide part 56 relative to the intermediate transfer belt 31 while maintaining a posture in which the angle θ between the virtual tangent L2 of the inner roll 32B perpendicular to line L1 and the intermediate virtual extension line L3 along the planar portion 102A and the plate-shaped portion 104 of the plate-shaped portion 102 is equal. For example, the angle between the virtual tangent L2 of the inner roll 32B perpendicular to line L1 and the planar portion 102A of the guide part 56 is equal when the guide part 56 moves in a direction approaching the intermediate transfer belt 31 and when it moves in a direction away from the intermediate transfer belt 31. For example, the movement is made such that the angle between the virtual tangent L2 of the inner roll 32B perpendicular to line L1 and the planar portion 102A of the guide part 56 falls within a range of ±4 degrees from the angle before the movement. In other words, an equal angle means moving so that it falls within a range of ±4 degrees from the angle before the movement. The angle between the virtual tangent L2 of the inner roll 32B perpendicular to line L1 and the planar portion 102A of the guide portion 56 is preferably within ±4 degrees from the angle before movement, more preferably within ±3 degrees, and even more preferably within ±2 degrees. In the first embodiment, the angle θ between the virtual tangent L2 of the inner roll 32B perpendicular to line L1 and the intermediate virtual extension line L3 along the planar portion 102A of the plate-shaped portion 102 and the plate-shaped portion 104 is set to be within ±4 degrees from the angle before movement.

[0068] As an example, when the guide unit 56 is moved to the first position P1, the paper P guided by the guide unit 56 contacts the intermediate transfer belt 31 at contact point CP1 (see Figure 2). Also as an example, when the guide unit 56 is moved to the second position P2, the paper P guided by the guide unit 56 contacts the intermediate transfer belt 31 at contact point CP2 (see Figure 3). The contact points CP1 and CP2 where the paper P guided by the guide unit 56 contacts the intermediate transfer belt 31 are downstream of the pre-roll 70 in the circumferential direction of the intermediate transfer belt 31. In the first embodiment, the contact points CP1 and CP2 where the paper P guided by the guide unit 56 contacts the intermediate transfer belt 31 are set between the contact portion of the pre-roll 70 and the inner roll 32B in the circumferential direction of the intermediate transfer belt 31.

[0069] <Challenges of the image formation system in the comparative example> Here, we will explain the challenges of the image formation system in the comparative example.

[0070] Although not shown in the diagram, in the image forming system of the first comparative example, the toner image on the intermediate transfer belt is transferred to the paper P at the secondary transfer position formed by the secondary transfer roll and the inner roll. In this method, if a gap occurs between the intermediate transfer belt and the paper P just before the secondary transfer position, discharge occurs, leading to image quality defects such as white spots. In particular, discharge is more likely to occur when using a medium such as paper or film that is thicker than the specified thickness as a medium that requires high voltage for secondary transfer.

[0071] In contrast, although not shown in the diagram, in the image forming system of the second comparative example, the guide is rotated around its upstream end on the upstream side of the secondary transfer position in the transport direction of the paper P. For example, by rotating the guide around its upstream end, the downstream end of the guide is rotated away from the intermediate transfer belt. This increases the angle at which the paper P enters the intermediate transfer belt compared to before the rotation of the guide, thereby suppressing discharge.

[0072] However, in the image forming system of the second comparative example, rotating the guide unit alters the transportability of the thick paper P, and increasing the entry angle of the paper P into the intermediate transfer belt may cause scratches on the paper P. Scratches on the paper P may lead to poor image quality (image defects).

[0073] Furthermore, by rotating the guide section around its upstream end, the downstream end of the guide section moves closer to the intermediate transfer belt. This reduces the gap between the paper P and the intermediate transfer belt, which can cause toner to scatter on the smooth surface of the paper.

[0074] Therefore, the image forming system in the second comparative example has room for improvement in suppressing the occurrence of poor image quality (image defects).

[0075] <Mechanism and Effects> Next, the operation of the first embodiment will be described.

[0076] The image forming system 10 of the first embodiment includes an endless intermediate transfer belt 31, an inner roll 32B, a secondary transfer roll 60, a guide unit 56, and a moving unit 80. The intermediate transfer belt 31 moves in a circumferential direction and conveys the toner image that has been primary transferred to its outer surface. The inner roll 32B rotates and comes into contact with the intermediate transfer belt 31, transferring the toner image from the intermediate transfer belt 31 to the paper P at a secondary transfer position NT opposite the intermediate transfer belt 31. The secondary transfer roll 60 rotates and faces the inner roll 32B across the intermediate transfer belt 31, forming a potential difference between the inner roll 32B and the secondary transfer roll 60. The guide unit 56 is provided upstream of the paper P in the conveying direction relative to the secondary transfer position NT and guides the paper P to the secondary transfer position NT. Depending on the type of paper P, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 toward or toward the intermediate transfer belt 31 while maintaining an orientation that intersects with the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60.

[0077] In the image forming system 10, as described above, the discharge can be suppressed by moving the entire planar portion 102A of the guide section 56 toward or toward the intermediate transfer belt 31, depending on the type of paper P. Furthermore, the entire planar portion 102A of the guide section 56 is moved toward or toward the intermediate transfer belt 31 while maintaining its orientation in a direction intersecting the line L1. As a result, the transportability of thick paper P is less likely to change compared to when the entry angle of the paper P into the intermediate transfer belt changes, and damage to the paper P is less likely to occur.

[0078] Therefore, in the image forming system 10, the occurrence of image quality defects is suppressed compared to the case where only one end of the guide portion of the medium moves toward or away from the intermediate transfer body.

[0079] Furthermore, in the image forming system 10, when the paper P is thicker than a predetermined thickness, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 closer to the intermediate transfer belt 31 than when the paper P is of the predetermined thickness. Also, when a film medium is used instead of paper P, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 closer to the intermediate transfer belt 31 than when the paper P is of the predetermined thickness. As a result, the image forming system 10 suppresses the occurrence of image quality defects compared to when the position of the guide unit does not change when the paper P is thicker than a predetermined thickness or when the film medium is used.

[0080] Furthermore, in the image forming system 10, when the paper P has a surface smoother than a predetermined smoothness, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 away from the intermediate transfer belt 31 compared to when the paper has a predetermined smoothness. For example, with a smooth surface, if the distance between the paper P and the intermediate transfer belt 31 is small, the toner image on the intermediate transfer belt 31 may rub against the paper P, causing toner scattering. By increasing the distance between the paper P and the intermediate transfer belt 31, the toner image on the intermediate transfer belt 31 is less likely to rub against the paper P. Therefore, in the image forming system 10, the occurrence of image quality defects due to toner scattering is suppressed compared to when the position of the guide unit does not change when the paper P has a surface smoother than a predetermined smoothness.

[0081] Furthermore, in the image forming system 10, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 toward or toward the intermediate transfer belt in accordance with the secondary transfer voltage applied to the inner roll 32B. This allows the distance between the intermediate transfer belt 31 and the paper P to be adjusted in accordance with the secondary transfer voltage applied to the inner roll 32B. Therefore, in the image forming system 10, the occurrence of image quality defects is suppressed compared to the case where the position of the guide unit does not change with changes in the secondary transfer voltage.

[0082] Furthermore, in the image forming system 10, when the secondary transfer voltage is higher than the reference voltage, the moving unit 80 moves the entire planar portion 102A of the guide unit 56 closer to the intermediate transfer belt 31 than when the secondary transfer voltage is below the reference voltage. For example, when the secondary transfer voltage is higher than the reference voltage, the distance between the intermediate transfer belt 31 and the paper P is reduced. Conversely, when the secondary transfer voltage is below the reference voltage, the distance between the intermediate transfer belt 31 and the paper P is increased. For example, when the paper P or film medium is thicker than a specified thickness, the secondary transfer voltage is often higher than the reference voltage. When the secondary transfer voltage is higher than the reference voltage, pre-discharge is likely to occur between the intermediate transfer belt 31 and the paper P. By reducing the distance between the intermediate transfer belt 31 and the paper P, pre-discharge is less likely to occur. Therefore, in the image forming system 10, the occurrence of image quality defects is suppressed compared to the case where the position of the guide unit does not change when the secondary transfer voltage is higher than the reference voltage.

[0083] Furthermore, the image forming system 10 is equipped with a pre-roll 70 that contacts the inside of the intermediate transfer belt 31, located downstream of the primary transfer position T in the circumferential direction of the intermediate transfer belt 31, and upstream of the secondary transfer roll 60 in the circumferential direction of the intermediate transfer belt 31. In addition, the contact points CP1 and CP2 where the paper P guided by the guide unit 56 contacts the intermediate transfer belt are located downstream of the pre-roll 70 in the circumferential direction of the intermediate transfer belt 31. As a result, the paper P can be transported upstream of the secondary transfer position NT with minimal bending, making it less likely for the paper P to bend. Therefore, in the image forming system 10, the occurrence of scratches on the paper P is suppressed compared to a case where the contact points where the paper P guided by the guide unit contacts the intermediate transfer belt are located downstream of the primary transfer position in the circumferential direction of the intermediate transfer belt and upstream of the pre-roll.

[0084] Furthermore, in the image forming system 10, when the guide section 56 moves toward or toward the intermediate transfer belt 31, the angle between the virtual tangent L2 of the inner roll 32B perpendicular to line L1 and the planar portion 102A of the guide section 56 moves so that it falls within ±4 degrees of the angle before the movement. As a result, the angle at which the paper P enters the intermediate transfer belt 31 does not change significantly, the transportability of the paper P does not change easily, and the paper P is less likely to bend. Therefore, in the image forming system 10, the occurrence of scratches on the paper P is suppressed compared to the case where the angle between the virtual tangent and the paper contact portion of the guide section changes when the guide section moves toward or toward the intermediate transfer belt.

[0085] [Second Embodiment] Next, the image forming system of the second embodiment will be described. Note that components identical to those of the first embodiment described above will be given the same numbers and their descriptions will be omitted.

[0086] As shown in Figure 4, in the image forming system 150 of the second embodiment, the range of movement of the guide unit 56 moved by the moving unit 152 is different from that of the image forming system 10 of the first embodiment.

[0087] The movable part 152 includes a cam 154 that contacts the lower surface (the surface opposite to the plate-shaped part 104) of the planar portion 102A of the plate-shaped part 102, and a motor 156 that rotates the shaft portion 155 of the cam 154. The movable part 152 moves the guide portion 56 in a direction closer to or further away from the intermediate transfer belt 31 by the rotation of the cam 154.

[0088] The moving unit 152 moves the entire planar portion 102A of the guide unit 56 in a direction approaching or away from the intermediate transfer belt 31, while maintaining its orientation in a direction intersecting the line L1, depending on the type of paper P. As an example, the moving unit 152 moves the guide unit 56 to a first position P161, a second position P162, and a third position P163 by rotating the cam 154 and moving the guide unit 56 in the vertical direction (arrow E direction). The first position P161 is a reference position in the middle of the vertical direction. The second position P162 is above the first position P161 (+H direction) and is close to the intermediate transfer belt 31. The third position P163 is below the first position P161 (-H direction) and is far from the intermediate transfer belt 31.

[0089] As shown in Figure 5, at the first position P161, the upstream end 102C of the planar portion 102A of the plate-shaped portion 102 in the guide portion 56 is positioned on a line L5 perpendicular to the line L4 connecting the centers of the upper and lower register rolls 54. The planar portion 102A is the part that the paper P contacts. The line L4 connecting the centers of the upper and lower register rolls 54 is the tangent to the contact portion of the upper and lower register rolls 54.

[0090] In Figure 5, undesirable positions of the guide portion 56 in the vertical direction are indicated by dashed lines. If the guide portion 56 moves too far upward in the vertical direction, the paper P guided by the guide portion 56 will come into contact with the intermediate transfer belt 31 on the pre-roll 70, which is undesirable. Also, if the guide portion 56 moves too far downward in the vertical direction, the paper P guided by the guide portion 56 will come into contact with the secondary transfer belt 36 on the secondary transfer roll 60, which is undesirable. The other configurations of the image forming system 150 are the same as those of the image forming system 10 of the first embodiment.

[0091] In the image forming system 150 of the second embodiment, the same operation and effect can be obtained with the same configuration as the image forming system 10 of the first embodiment.

[0092] [Third Embodiment] Next, the image forming system of the third embodiment will be described. Note that components identical to those of the first and second embodiments described above will be given the same numbers and their descriptions will be omitted.

[0093] As shown in Figure 6, the image forming system 200 of the third embodiment has a different inclination of the guide section 202 with respect to the horizontal direction compared to the image forming system 10 of the first embodiment.

[0094] The guide section 202 comprises a pair of plate-like sections 102 and 104. The planar portion 102A of the plate-like section 102 in the guide section 202 is positioned in a direction (for example, a 90-degree direction) that intersects the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60. That is, the planar portion 102A of the plate-like section 102 in the guide section 202 is positioned along a virtual tangent line L2 of the inner roll 32B that is perpendicular to the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60.

[0095] The moving unit 80 includes a cam 82 that contacts the lower surface (the surface opposite to the plate-shaped part 104) of the planar portion 102A of the plate-shaped portion 102, and a motor 84 that rotates the shaft portion 83 of the cam 82. Depending on the type of paper P, the moving unit 80 moves the entire planar portion 102A of the guide portion 56 relative to the intermediate transfer belt 31 while maintaining an orientation that intersects the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60 (for example, in the 90-degree direction). In other words, the moving unit 80 moves the entire planar portion 102A of the guide portion 56 relative to the intermediate transfer belt 31 while maintaining an orientation that aligns with a virtual tangent L2 of the inner roll 32B that is perpendicular to the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60.

[0096] As an example, the transport direction of the paper P guided by the guide section 202 is along the virtual tangent line L2 of the inner roll 32B, which is perpendicular to the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60. The planar portion 102A, which is an example of the media contact area of ​​the plate-shaped portion 102 in the guide section 202, is planar when viewed from the side.

[0097] As an example, the moving unit 80 moves the guide unit 202 in the vertical direction (direction of arrow F) by rotating the cam 82. The moving unit 80 moves the guide unit 202 to a first position P211 (see Figure 6) that is far from the intermediate transfer belt 31 by bringing the smaller diameter portion of the cam 82 into contact with the plate-shaped portion 102. The moving unit 80 also moves the guide unit 202 to a second position P212 (see Figure 7) that is closer to the intermediate transfer belt 31 by bringing the larger diameter portion of the cam 82 into contact with the plate-shaped portion 102. In the first embodiment, the moving unit 80 moves the guide unit 56 to the first position P211 which is lower in the vertical direction and to the second position P212 which is upper in the vertical direction. The other configurations of the image forming system 200 are the same as those of the image forming system 10 in the first embodiment.

[0098] In the third embodiment of the image forming system 200, in addition to the operations and effects of the same configuration as the image forming system 10 of the first embodiment, the following operations and effects can be obtained.

[0099] In the image forming system 200, the transport direction of the paper P guided by the guide section 202 is along a virtual tangent L2 of the secondary transfer roll 60 that is perpendicular to the line L1 connecting the center of the inner roll 32B and the center of the secondary transfer roll 60. As a result, when the paper P guided by the guide section 202 is transported to the secondary transfer position NT, the paper P is transported in a nearly straight shape with almost no curvature. Therefore, the paper P is less likely to bend. Consequently, in the image forming system 200, the transport direction of the paper P guided by the guide section is in a direction that intersects the virtual tangent of the secondary transfer roll that is perpendicular to the line connecting the center of the opposing roll and the center of the secondary transfer roll, thus suppressing the occurrence of scratches on the paper P.

[0100] Furthermore, in the image forming system 200, the planar portion 102A of the plate-shaped portion 102 in the guide portion 202 that contacts the paper P is planar when viewed from the side. Therefore, in the image forming system 200, the occurrence of scratches on the paper P is suppressed compared to when the media contact portion of the guide portion is curved or bent.

[0101] Figure 8 is a graph showing the relationship between the height of the guide section 202 when the paper P enters the secondary transfer position NT and the occurrence of white spots due to pre-discharge immediately before the secondary transfer position NT. The horizontal axis of the graph in Figure 8 shows how much the height of the guide section 202 has been raised from the reference height "0". The vertical axis of the graph in Figure 8 shows the occurrence of white spots due to pre-discharge in steps, with larger values ​​indicating a worsening of the white spot occurrence. The incidence angle of the intermediate transfer belt 31 to the secondary transfer position NT in the horizontal direction is 6 degrees, and the process speed is 1000 mm / s. Paper P is paper with a specified basis weight (500 gsm). As shown in Figure 8, it can be seen that raising the vertical height of the guide section 202 improves the occurrence of white spots due to pre-discharge. Therefore, it can be seen that narrowing the gap between the paper P and the intermediate transfer belt 31 improves the occurrence of white spots due to pre-discharge.

[0102] [Fourth Embodiment] Next, the image forming system of the fourth embodiment will be described. Note that components identical to those of the first to third embodiments described above will be given the same numbers and their descriptions will be omitted.

[0103] In contrast to the image forming system 150 of the second embodiment (see Figure 4), where the position of the register roll 54 was fixed, the image forming system 300 of the fourth embodiment differs in that the position of the register roll 302 is moved, as shown in Figures 9 and 10. The register roll 302 is an example of an adjustment roll. The register roll 302 is located upstream of the guide section 56 in the paper transport direction and adjusts the transport timing of the paper P to be transported to the secondary transfer position NT. The register roll 302 consists of a pair of upper and lower rolls.

[0104] The image forming system 300 includes a moving unit 310 that moves the guide unit 56 and the register roll 302 together in a direction toward or toward the intermediate transfer belt 31. Although not shown in the figures, the image forming system 300 is provided with a support frame that integrally supports the guide unit 56 and the register roll 302. The register roll 302 is rotatably supported on the support frame. The moving unit 310 includes a cam 312 that contacts the support frame near the lower surface of the planar portion 102A of the plate-shaped portion 102, and a motor 156 that rotates the shaft portion 313 of the cam 312. As an example, the moving unit 310 moves the support frame by rotating the cam 312, thereby moving the guide unit 56 and the register roll 302 together in the vertical direction (direction of arrow E). As a result, the moving unit 310 moves the register roll 302 toward or toward the intermediate transfer belt 31 depending on the movement position of the guide unit 56. As an example, the moving unit 310 moves the register roll 302 vertically (in the direction of arrow E) by the same distance as the guide unit 56. The moving unit 310 is an example of a second moving unit that is also used as the moving unit for moving the guide unit 56.

[0105] Specifically, the moving part 310 moves the guide part 56 to a first position P161, a second position P162, and a third position P163 in the vertical direction (arrow E direction) by the rotation of the cam 312. The first position P161 is a reference position in the middle of the vertical direction. The second position P162 is above the first position P161 (+H direction) and is close to the intermediate transfer belt 31. The third position P163 is below the first position P161 (-H direction) and is farther from the intermediate transfer belt 31.

[0106] At this time, the moving unit 310 moves the register roll 302 to a first position P321, a second position P322, and a third position P323 in the vertical direction (arrow E direction) in accordance with the movement position of the guide unit 56. The first position P321 is a reference position midway in the vertical direction. The second position P322 is above the first position P321 (+H direction) and is close to the intermediate transfer belt 31. The third position P323 is below the first position P321 (-H direction) and is far from the intermediate transfer belt 31. The other configurations of the image forming system 300 are the same as those of the image forming system 150 of the second embodiment.

[0107] In the image forming system 300 of the fourth embodiment, in addition to the functions and effects of the same configuration as the image forming system 10 of the first embodiment, the following functions and effects can be obtained.

[0108] The image forming system 300 includes a register roll 302 and a moving unit 310 that moves the register roll 302 toward or toward the intermediate transfer belt 31 according to the movement position of the guide unit 56. As a result, when the paper P conveyed by the register roll 302 is guided to the secondary transfer position NT by the guide unit 56, the paper P is less likely to bend, and bending of the paper P is less likely to occur. Therefore, in the image forming system 300, the occurrence of scratches on the paper P is suppressed compared to when the position of the adjustment roll is fixed when the guide unit moves.

[0109] [supplementary explanation] In the image forming systems 10, 150, 200, and 300 of the first to fourth embodiments, the guide section 56 and 202 were composed of a pair of plate-like sections 102 and 104, with the plate-like section 104 being planar and the main part of the plate-like section 102 being planar. However, the present disclosure is not limited to this configuration. For example, the guide section may be composed of a plate-like section bent in the middle of the paper transport direction. Also, for example, the guide section does not have to be a pair of plate-like sections, but may be composed of a single plate-like section.

[0110] Furthermore, in the image forming systems 10, 150, 200, and 300 of the first to fourth embodiments, a secondary transfer voltage was applied to the inner roll 32B, but the present disclosure is not limited to this configuration. For example, a configuration in which the secondary transfer voltage is applied to the secondary transfer roll 60 is also possible.

[0111] Furthermore, in the image forming system 300 of the fourth embodiment, the moving unit 310 moved the guide unit 56 and the register roll 302 together, but the present disclosure is not limited to this configuration. For example, a moving unit for moving the guide unit 56 and a second moving unit for moving the register roll 302 may be provided separately.

[0112] In the image forming systems 10, 150, 200, and 300 of the first to fourth embodiments, the paper P is transported horizontally at the secondary transfer position NT, and the toner image on the intermediate transfer belt 31 is transferred to the paper P. However, the present disclosure is not limited to this configuration. For example, in the image forming system, the paper P may be transported vertically at the secondary transfer position NT, and the toner image on the intermediate transfer belt 31 may be transferred to the paper P. In this case, the system may be configured to include a moving part that moves the entire media contact area in the guide part toward or toward the intermediate transfer belt while maintaining an orientation that intersects the line connecting the center of the transfer rotating body and the center of the opposing rotating body, depending on the type of paper P.

[0113] In the image forming systems 10, 150, 200, and 300 of the first to fourth embodiments, paper P was used, but a medium such as film may be used instead of paper P.

[0114] Although the present invention has been described in detail with respect to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to these embodiments, and that various other embodiments are possible within the scope of the present invention.

[0115] [Note] (((1))) An endless intermediate transfer body that is wrapped around multiple rolls and moves in a circumferential direction, transporting the toner image that has been primarily transferred to its outer surface, A transfer rotating body that rotates and comes into contact with the intermediate transfer body, and transfers the toner image of the intermediate transfer body to the medium at a secondary transfer position facing the intermediate transfer body, A counter rotating body that rotates and faces the transfer rotating body with the intermediate transfer body in between, and forms a potential difference between itself and the transfer rotating body, A guide unit is provided on the upstream side in the transport direction of the medium with respect to the secondary transfer position, and guides the medium to the secondary transfer position. A moving part that moves the entire media contact portion of the guide part toward or toward the intermediate transfer body while maintaining an orientation that intersects the line connecting the center of the transfer rotating body and the center of the opposing rotating body, depending on the type of medium, An image forming system having the following features.

[0116] (((2))) The image forming system according to (((1))), wherein when the medium is a medium or film medium thicker than a predetermined thickness, the moving part moves the entire medium contact portion of the guide part in a direction closer to the intermediate transfer body than when the medium is of the predetermined thickness.

[0117] (((3))) The image forming system according to (((1))) or (((2))), wherein when the medium has a surface smoother than a predetermined smoothness, the moving part moves the entire medium contact portion of the guide part away from the intermediate transfer body more than when the medium has the predetermined smoothness.

[0118] (((4))) The image forming system according to any one of (((1))) to (((3))), wherein the moving part moves the entire medium contact portion of the guide part toward or toward the intermediate transfer body in accordance with the secondary transfer voltage applied to the transfer rotating body or the opposing rotating body.

[0119] (((5))) The image forming system according to ((4))) wherein the moving part moves the entire medium contact portion of the guide part in a direction closer to the intermediate transfer body than when the secondary transfer voltage is higher than the reference voltage.

[0120] (((6))) A rotating member is provided that contacts the inside of the intermediate transfer body, located downstream in the circumferential direction of the intermediate transfer body from the primary transfer position where the toner image is transferred, and upstream in the circumferential direction of the intermediate transfer body from the opposing rotating body, The image forming system according to any one of (((1))) to (((5))), wherein the contact point where the medium guided by the guide comes into contact with the intermediate transfer body is downstream of the rotating member in the circumferential direction of the intermediate transfer body.

[0121] (((7))) The image forming system according to any one of (((1))) to (((6))), wherein the transport direction of the medium guided by the guide section is along a virtual tangent to the transfer rotating body that is perpendicular to the line connecting the center of the transfer rotating body and the center of the opposing rotating body.

[0122] (((8))) The image forming system according to (((7))), wherein the media contact portion in the guide portion is planar in a side view.

[0123] (((9))) The image forming system according to any one of (((1))) to (((8))), wherein when the guide is moved by the moving part toward the intermediate transfer body and when it is moved toward the intermediate transfer body, the angle between the virtual tangent to the transfer rotation body which is perpendicular to the line connecting the center of the transfer rotation body and the center of the opposing rotation body and the media contact portion of the guide is moved to within ±4 degrees from the angle before the movement.

[0124] (((10))) An adjustment roll is provided upstream of the guide section in the medium transport direction and adjusts the transport timing of the medium, A second moving part moves the adjustment roll in a direction toward or toward the intermediate transfer body, depending on the movement position of the guide part, An image forming system according to any one of (((1))) to (((9))) having

[0125] According to the image forming system described in (((1))), the occurrence of image quality defects is suppressed compared to the case in which only one end of the guide portion of the medium is moved in a direction toward or away from the intermediate transfer body.

[0126] According to the image forming system described in (((2))), the occurrence of image quality defects is suppressed compared to the case where the position of the guide portion does not change when the medium is thicker than a specified thickness or when it is a film medium.

[0127] According to the image forming system described in (((3))), the occurrence of image quality defects due to toner scattering is suppressed compared to the case where the position of the guide does not change when the medium has a surface smoother than a specified degree of smoothness.

[0128] According to the image forming system described in (((4))), the occurrence of image quality defects is suppressed compared to the case where the position of the guide does not change by changing the secondary transfer voltage.

[0129] According to the image forming system described in (((5))), the occurrence of image quality defects is suppressed compared to the case where the position of the guide does not change when the secondary transfer voltage is higher than the reference voltage.

[0130] According to the image forming system described in (((6))), the occurrence of scratches on the medium is suppressed compared to the case where the contact point where the medium guided by the guide comes into contact with the intermediate transfer body is downstream of the primary transfer position in the circumferential direction of the intermediate transfer body and upstream of the rotating member.

[0131] According to the image forming system described in (((7))), the occurrence of scratches on the medium is suppressed compared to the case where the transport direction of the medium guided by the guide section is in a direction that intersects with the virtual tangent of the transfer rotation body which is perpendicular to the line connecting the center of the transfer rotation body and the center of the opposing rotation body.

[0132] According to the image forming system described in ((8)), the occurrence of scratches on the media is suppressed compared to the case where the media contact area in the guide section is curved or bent.

[0133] According to the image forming system described in (((9))), the occurrence of scratches on the medium is suppressed compared to the case where the angle between the virtual tangent and the medium contact area of ​​the guide changes when the guide moves toward the intermediate transfer body and when it moves toward the intermediate transfer body.

[0134] According to the image forming system (((10))), the occurrence of scratches on the media is suppressed compared to the case where the position adjustment roll is fixed when the guide unit moves. [Explanation of Symbols]

[0135] 10 Image Forming Systems 31. Intermediate Transfer Belt (An example of an intermediate transfer body) 32B Inner Roll (Example of a Transfer Rotating Body) 34 Secondary transfer section 54. Register Roll (An example of an adjustment roll) 56 Information Department 60. Secondary transfer roll (an example of an opposing rotating body) 70. Pre-roll (an example of a rotating member) 80 Mobile unit 102 Plate-shaped part (an example of a guide part) 102A Planar portion (an example of a media contact area) 102C Upstream end 104 Plate-shaped part (an example of a guide part) 150 Image Forming Systems 152 Mobile section 200 Image Forming Systems 202 Information Department 300 Image Forming Systems 302 Register Roll (Example of an adjustment roll) 310 Mobile Unit (Example of the Second Mobile Unit) CP1 contact point CP2 contact point L1 line L2 virtual tangent NT secondary transfer position P paper (an example of a medium)

Claims

1. An endless intermediate transfer body that is wrapped around multiple rolls and moves in a circumferential direction, transporting the toner image that has been primarily transferred to its outer surface, A transfer rotating body that rotates and comes into contact with the intermediate transfer body, and transfers the toner image of the intermediate transfer body to the medium at a secondary transfer position facing the intermediate transfer body, A counter rotating body that rotates and faces the transfer rotating body with the intermediate transfer body in between, and forms a potential difference between itself and the transfer rotating body, A guide unit is provided on the upstream side in the transport direction of the medium with respect to the secondary transfer position, and guides the medium to the secondary transfer position. A moving part that moves the entire media contact portion of the guide part toward or toward the intermediate transfer body while maintaining an orientation that intersects the line connecting the center of the transfer rotating body and the center of the opposing rotating body, depending on the type of medium, An image forming system having the following features.

2. The image forming system according to claim 1, wherein when the medium is a medium or film medium thicker than a predetermined thickness, the moving part moves the entire medium contact portion of the guide part in a direction closer to the intermediate transfer body than when the medium is of the predetermined thickness.

3. The image forming system according to claim 1, wherein when the medium has a surface smoother than a predetermined smoothness, the moving part moves the entire medium contact portion of the guide part in a direction away from the intermediate transfer body compared to when the medium has the predetermined smoothness.

4. The image forming system according to claim 1, wherein the moving part moves the entire medium contact portion of the guide part toward or toward the intermediate transfer body in accordance with the secondary transfer voltage applied to the transfer rotating body or the opposing rotating body.

5. The image forming system according to claim 4, wherein the moving part moves the entire medium contact portion of the guide part in a direction closer to the intermediate transfer body when the secondary transfer voltage is higher than the reference voltage, compared to when the secondary transfer voltage is less than or equal to the reference voltage.

6. A rotating member is provided that contacts the inside of the intermediate transfer body, located downstream in the circumferential direction of the intermediate transfer body from the primary transfer position where the toner image is transferred, and upstream in the circumferential direction of the intermediate transfer body from the opposing rotating body, The image forming system according to claim 1, wherein the contact point where the medium guided by the guide comes into contact with the intermediate transfer body is downstream of the rotating member in the circumferential direction of the intermediate transfer body.

7. The image forming system according to claim 1, wherein the transport direction of the medium guided by the guide portion is along a virtual tangent to the transfer rotating body that is perpendicular to the line connecting the center of the transfer rotating body and the center of the opposing rotating body.

8. The image forming system according to claim 7, wherein the media contact portion in the guide portion is planar when viewed from the side.

9. The image forming system according to claim 1, wherein when the guide portion is moved by the moving portion in a direction approaching the intermediate transfer body and when it is moved in a direction away from the intermediate transfer body, the angle between the virtual tangent of the transfer rotation body which is perpendicular to the line connecting the center of the transfer rotation body and the center of the opposing rotation body and the media contact portion of the guide portion is moved within a range of ±4 degrees from the angle before the movement.

10. An adjustment roll is provided upstream of the guide section in the medium transport direction and adjusts the transport timing of the medium, A second moving part moves the adjustment roll in a direction toward or toward the intermediate transfer body, depending on the movement position of the guide part, The image forming system according to claim 1, having the following features.

Images