Image forming device

Abstract

To suppress fluctuation in a rotational speed generating in a transfer cylinder, compared with the case where the fluctuation in load torque generating in a pressure cylinder becomes the fluctuation in the rotational speed of the pressure cylinder as it is, in a constitution where the rotation of the pressure cylinder synchronizes with the rotation of the transfer cylinder.SOLUTION: An image forming device includes: a transfer cylinder which sandwiches a recording medium to be conveyed between itself and a transfer member on which an image is transferred, while rotating, and for transferring the image to the recording medium; a heating roll for heating the recording medium to be conveyed while rotating; a pressure cylinder for rotating in synchronization with the rotation of the transfer cylinder, and for pressurizing the recording medium to be conveyed toward the heating roll; an approaching / separating mechanism which includes a cam member for rotating with the pressure cylinder and a cam follower connected to the heating roller and pressed against a cam surface of the cam member, and which allows the heating roll to approach / be separated from the pressure cylinder; and a suppression part for suppressing load torque occurring in the pressure cylinder by the approaching / separating mechanism allowing the heating roll to approach / be separated from the pressure cylinder.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] The transfer device described in Patent Document 1 has a transfer roller that faces an image carrier that carries an image, rotates around a rotation axis, and has a roller base material with a recess on its peripheral surface, and is equipped with a transfer roller that transfers the image carried on the image carrier to a recording medium while the recess is not facing the image carrier, a pressing section that presses the transfer roller against the image carrier, and an abutment section that is provided at a position corresponding to the recess in the direction of the rotation axis, and the abutment section has a peripheral surface that abuts against a support section arranged in a drive transmission section that transmits drive to the image carrier while the recess faces the image carrier, and an elastic member is provided on the peripheral surface of the abutment section. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2010-281895 A Summary of the Invention [Problem to be solved by the invention]

[0004] The image forming apparatus includes a transfer cylinder that rotates to transfer an image to a recording medium, a heating roll that is disposed downstream of the transfer cylinder in the recording medium transport direction and heats the recording medium transported while rotating, and a pressure cylinder that is disposed opposite the heating roll and presses the recording medium transported while rotating toward the heating roll. Furthermore, the image forming apparatus includes a mechanism for moving the heating roll toward and away from the pressure cylinder, and the rotation of the pressure cylinder and the rotation of the transfer cylinder are synchronized.

[0005] In such an image forming apparatus, the approaching and separating mechanism moves the heating roll toward and away from the pressure cylinder, causing fluctuations in the load torque on the pressure cylinder, which in turn causes fluctuations in the rotation speed of the pressure cylinder. Furthermore, the rotation of the pressure cylinder and the rotation of the transfer cylinder are synchronized, which causes fluctuations in the rotation speed of the transfer cylinder.

[0006] The object of the present disclosure is to suppress fluctuations in the rotational speed of the transfer cylinder in a configuration in which the rotation of the pressure cylinder and the rotation of the transfer cylinder are synchronized, compared to a case in which fluctuations in the load torque generated in the pressure cylinder directly result in fluctuations in the rotational speed of the pressure cylinder. [Means for solving the problem]

[0007] The image forming apparatus according to a first aspect of the present disclosure is characterized in that it comprises a transfer cylinder that rotates to pinch the transported recording medium between itself and a transfer member to which an image has been transferred, and transfers the image to the recording medium, a heating roll that is arranged downstream of the transfer cylinder in the transport direction of the recording medium and heats the transported recording medium while rotating, a pressure cylinder that is arranged opposite the heating roll, rotates in sync with the rotation of the transfer cylinder, and presses the transported recording medium toward the heating roll, a cam member that rotates together with the pressure cylinder, and a cam follower that is connected to the heating roll and is pressed against the cam surface of the cam member, and is equipped with a proximity and separation mechanism that moves the heating roll closer to and away from the pressure cylinder, and a suppression unit that suppresses the load torque generated on the pressure cylinder by the proximity and separation mechanism moving the heating roll closer to and away from the pressure cylinder.

[0008] An image forming apparatus according to a second aspect of the present disclosure is characterized in that, in the image forming apparatus described in the first aspect, the suppression section includes another cam member attached to the pressure cylinder and rotating together with the pressure cylinder, and another cam follower pressed against another cam surface of the other cam member.

[0009] An image forming apparatus according to a third aspect of the present disclosure is characterized in that, in the image forming apparatus described in the second aspect, when viewed from the direction of the rotation axis of the pressure cylinder, the other cam follower is arranged on the opposite side of the cam follower across the rotation axis of the pressure cylinder.

[0010] An image forming apparatus according to a fourth aspect of the present disclosure is characterized in that, in the image forming apparatus described in the first aspect, the suppression section includes a first gear attached to the pressure cylinder and rotating together with the pressure cylinder, a second gear that meshes with the first gear to provide a reduction ratio that is an integer multiple of 2 or more, another cam member attached to the second gear and rotating together with the second gear, and another cam follower pressed against another cam surface of the other cam member.

[0011] An image forming apparatus according to a fifth aspect of the present disclosure is the image forming apparatus according to the fourth aspect, characterized in that N other cam followers are provided in an N-times case. Effect of the Invention

[0012] According to the image forming device of the first aspect of the present disclosure, in a configuration in which the rotation of the pressure cylinder and the rotation of the transfer cylinder are synchronized, the fluctuations in the rotation speed of the transfer cylinder can be suppressed compared to a case in which the fluctuations in the load torque generated in the pressure cylinder directly result in fluctuations in the rotation speed of the pressure cylinder.

[0013] According to the image forming apparatus of the second aspect of the present disclosure, the load torque can be reduced with a simple configuration compared to the case where torque is electrically applied to the rotating shaft of the pressure cylinder to reduce the load torque generated in the pressure cylinder.

[0014] According to the image forming device of the third aspect of the present disclosure, when viewed from the direction of the rotation axis of the pressure cylinder, bending of the rotation axis can be suppressed compared to when the cam follower and the other cam follower are arranged on the same side of the rotation axis.

[0015] According to the image forming apparatus according to the fourth aspect of the present disclosure, the pressing force applied to the other cam follower can be reduced to an integer fraction as compared to when the other cam member is attached to the pressure cylinder.

[0016] According to the image forming apparatus according to the fifth aspect of the present disclosure, the pressing force applied to the other cam follower can be made weaker than when there is one other cam follower. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram showing an image forming apparatus according to a first embodiment of the present disclosure. [Diagram 2] 1 is a schematic configuration diagram illustrating a toner image forming unit of an image forming apparatus according to a first embodiment of the present disclosure. [Diagram 3] 1 is a perspective view showing a chain gripper of an image forming apparatus according to a first embodiment of the present disclosure. FIG. [Figure 4] FIG. 2 is a perspective view showing a secondary transfer roll and the like of the transfer device according to the first embodiment of the present disclosure. [Diagram 5] FIG. 2 is a perspective view showing a heating roll, a pressure roll, and the like of the image forming apparatus according to the first embodiment of the present disclosure. [Figure 6] FIG. 2 is a cross-sectional view showing a heating roll, a pressure roll, and the like of the image forming apparatus according to the embodiment of the present disclosure. [Figure 7] 2 is a front view showing a proximity / separation mechanism, a suppression unit, and the like of the image forming apparatus according to the first embodiment of the present disclosure. FIG. [Figure 8] 5A, 5B, and 5C are operational diagrams illustrating the operation of the approach and separation mechanism of the image forming apparatus according to the first embodiment of the present disclosure. [Figure 9] 4 is a graph showing torque applied to a pressure roll of the image forming apparatus according to the first embodiment of the present disclosure. [Figure 10] 13 is a front view showing a proximity / separation mechanism, a suppression unit, and the like of an image forming apparatus according to a second embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] First Embodiment An example of an image forming apparatus according to a first embodiment of the present disclosure will be described with reference to Figures 1 to 9. Note that, in the figures, arrow H indicates the up-down direction (vertical direction) of the apparatus, arrow W indicates the width direction (horizontal direction) of the apparatus, and arrow D indicates the depth direction (horizontal direction) of the apparatus.

[0019] The image forming apparatus 10 according to this embodiment is an electrophotographic image forming apparatus that forms a toner image on a sheet member P as a recording medium. As shown in Fig. 1, the image forming apparatus 10 includes a storage section 50, an image forming section 12, and a control section 18 that controls each section.

[0020] (Storage section 50) The storage section 50 has a function of storing sheet materials P. As shown in FIG 1, the storage section 50 includes a stacking section 78 on which the sheet materials P are stacked, and a delivery roll 58 that delivers the topmost sheet material P stacked on the stacking section 78 to the supply path 40.

[0021] (Image forming unit 12) The image forming unit 12 has a function of forming an image on the sheet member P by an electrophotographic method. As shown in Fig. 1, the image forming unit 12 is disposed above the storage unit 50. 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 in the toner image forming unit 20 to the sheet member P, and a fixing device 100 that fixes the toner image to the sheet member P.

[0022] [Toner image forming unit 20] As shown in Fig. 1, a plurality of toner image forming units 20 are provided to form toner images for each color. The image forming unit 12 is provided with toner image forming units 20 for a total of four colors: yellow (Y), magenta (M), cyan (C), and black (K). Y, M, C, and K shown in Fig. 1 indicate components corresponding to the above-mentioned colors.

[0023] The toner image forming units 20Y, 20M, 20C, and 20K are basically configured in the same manner except for the toners used.

[0024] 1, the toner image forming units 20Y, 20M, 20C, and 20K are aligned along the horizontal portion of a transfer belt 31 provided in a transfer device 30. In the following description, when there is no need to distinguish between the toner image forming units 20Y, 20M, 20C, and 20K, the alphabets at the end of the names will be omitted.

[0025] 2, the toner image forming unit 20 includes an image carrier 21 that rotates in the direction of the arrow A01 in the figure, and a charger 22 that charges the image carrier 21. The toner image forming unit 20 further includes an exposure device 23 that exposes the image carrier 21 charged by the charger 22 to light to form an electrostatic latent image, and a developing device 24 that develops the electrostatic latent image with toner to form a toner image.

[0026] [Transfer device 30] The transfer device 30 has a function of primarily transferring the toner images of the image carriers 21 of each color onto an intermediate transfer body in a superimposed manner, and then secondarily transferring the superimposed toner images onto a sheet member P. Specifically, as shown in FIG. 1, the transfer device 30 includes a transfer belt 31 as an intermediate transfer body, a plurality of rolls 32, a primary transfer roll 33, a transfer cylinder 36, and a scraping member 38.

[0027] The transfer belt 31 is endless and wound around multiple rolls 32 so as to assume an inverted triangular posture. The toner image forming units 20Y, 20M, 20C, and 20K are aligned along the upper horizontal portion of the transfer belt 31. The transfer belt 31 rotates in the direction of arrow B when at least one of the multiple rolls 32 is driven to rotate.

[0028] In the following description, among the multiple rolls 32, the roll 32 arranged so as to push out the inclined portion of the transfer belt 31 on one side in the device width direction (the left side in the drawing) is referred to as roll 32a, and the roll 32 around which the portion of the transfer belt 31 on one side in the device width direction is wound is referred to as roll 32b. Furthermore, the roll 32 arranged upstream of the roll 32a in the rotation direction of the transfer belt 31 is referred to as roll 32c.

[0029] The roll 32b functions as a drive roll that is rotationally driven by a driving force applied from a drive source 34. The roll 32c presses the transfer belt 31 from the back surface of the transfer belt 31 and functions as a tension applying roll that applies tension to the transfer belt 31.

[0030] The primary transfer rolls 33 are disposed on the opposite side of the image carriers 21 of the respective colors across the transfer belt 31. The primary transfer rolls 33 have a function of transferring the toner images formed on the image carriers 21 to the transfer belt 31 at a primary transfer position T between the image carriers 21 and the primary transfer rolls 33.

[0031] The transfer cylinder 36 is disposed on the opposite side of the roll 32a across the transfer belt 31, and is driven to rotate. The transfer cylinder 36 has a function of transferring the toner image transferred onto the transfer belt 31 onto the sheet member P at a secondary transfer position NT between the transfer belt 31 and the transfer cylinder 36.

[0032] The scraping member 38 is disposed between the roll 32a and the roll 32b in the rotation direction of the transfer belt 31, and has a function of scraping off the deposits adhering to the surface of the transfer belt 31 from the transfer belt 31.

[0033] [Fixing device 100] The fixing device 100 has a function of fixing the toner image transferred to the sheet member P by the transfer device 30 onto the sheet member P. As shown in Fig. 1, the fixing device 100 includes a chain gripper 66 and a main heating section 120 that comes into contact with the sheet member P to heat the toner image.

[0034] -Chain Gripper 66- The chain gripper 66 includes a pair of chains 72, a leading end holding portion 68 that holds the leading end of the sheet material P, and sprockets 71, 73, 82, 84, and 86.

[0035] As shown in Fig. 3, the pair of chains 72 are disposed at a distance from each other in the apparatus depth direction, and the chains 72 are formed in an endless shape. As shown in Fig. 4, the pair of chains 72 are wound around a pair of sprockets 73 that are disposed at both axial ends of the transfer cylinder 36 and whose axial direction is the apparatus depth direction. The pair of chains 72 are also wound around a pair of sprockets 71 (see Fig. 5) that are disposed at one and the other axial ends of a pressure cylinder 140 (described later) and whose axial direction is the apparatus depth direction. The pair of chains 72 are also wound around a pair of sprockets 82, a pair of sprockets 84, and a pair of sprockets 86 that are disposed at an interval in the apparatus depth direction.

[0036] In addition, as shown in FIG. 1, sprockets 71 arranged on both ends of pressure cylinder 140 are arranged on one side in the device width direction (the left side in the figure) and above sprockets 73 arranged on both ends of transfer cylinder 36.

[0037] Moreover, when viewed from the depth direction of the device, the pair of sprockets 82 are disposed below sprocket 71. Furthermore, the pair of sprockets 86 are disposed below sprockets 73 and 82, on one side of sprocket 73 in the width direction of the device, and on the other side of sprocket 82 in the width direction of the device. The pair of sprockets 84 are disposed so as to lift the portion of chain 72 between sprockets 82 and 86 from the lower side to the upper side.

[0038] As shown in Figure 3, the tip holding portion 68 has an attachment member 75 extending in the device depth direction and a gripper 76 attached to the attachment member 75, and both side portions of the tip holding portion 68 in the device depth direction are respectively attached to a pair of chains 72.

[0039] A plurality of tip holders 68 are provided and are arranged at predetermined intervals along the circumferential direction (circumferential direction) of the chain 72 (see FIG. 1).

[0040] A plurality of grippers 76 are provided and attached to the attachment member 75 at predetermined intervals along the device depth direction. The grippers 76 have a function of holding the leading edge of the sheet material P. Specifically, the grippers 76 have claws 76a. The attachment member 75 is also formed with contact portions 75a (see FIG. 6) with which the claws 76a come into contact.

[0041] The gripper 76 is configured to hold the sheet material P by pinching the leading end of the sheet material P between the claw 76a and the contact portion 75a. Note that, for example, the claw 76a of the gripper 76 is pressed against the contact portion 75a by a spring or the like, and the claw 76a is moved toward and away from the contact portion 75a by the action of a cam or the like.

[0042] In this configuration, when a rotational force is transmitted to sprockets 71 and 73 among the multiple sprockets 71, 73, 82, 84, and 86 shown in FIG. 1, a pair of chains 72 rotates in the direction of arrow C in the figure.

[0043] Furthermore, when the leading end holding portion 68 attached to the pair of chains 72 reaches the sprocket 73, the gripper 76 of the leading end holding portion 68 pinches the leading end of the sheet material P transported along the supply path 40 to hold and receive the sheet material P. Then, the chain 72 revolving in the direction of the arrow C transports the sheet material P held by the leading end holding portion 68 toward the secondary transfer position NT. Furthermore, the revolving chain 72 transports the sheet material P toward the main heating unit 120. Also, at a position where the leading end of the sheet material P has passed through the main heating unit 120, the leading end holding portion 68 releases the leading end holding of the sheet material P, and the chain gripper 66 sends the sheet material P to the discharge path 42. Then, the sheet material P sent to the discharge path 42 is discharged to the outside of the device main body 10a.

[0044] -Main heating section 120- 1, the main heating section 120 is disposed downstream of the secondary transfer position NT in the conveying direction of the sheet member P. The main heating section 120 also includes a heating roll 130 that contacts the conveyed sheet member P to heat the sheet member P, and a pressure cylinder 140 that presses the sheet member P against the heating roll 130. Details of the main heating section 120 will be described later.

[0045] In this configuration, the pressure cylinder 140 presses the sheet member P toward the heating roll 130. Furthermore, the pressure cylinder 140 rotates by a rotational force transmitted from a driving member (not shown). The heating roll 130 rotates in response to the rotating pressure cylinder 140. Furthermore, the heating roll 130 and the pressure cylinder 140 sandwich and transport the sheet member P to which the toner image has been transferred, whereby the toner image is heated and fixed to the sheet member P.

[0046] (Function of Image Forming Apparatus) In the image forming apparatus 10 shown in Fig. 1, a toner image is formed on the sheet member P as follows. First, the charger 22 for each color shown in Fig. 2 uniformly negatively charges the surface of the image carrier 21 for each color at a predetermined potential. Next, based on image data input from the outside, the exposure device 23 irradiates the charged surface of the image carrier 21 for each color with exposure light to form an electrostatic latent image.

[0047] As a result, electrostatic latent images corresponding to the image data are formed on the surfaces of the image carriers 21. The developing devices 24 for each color develop the electrostatic latent images and visualize them as toner images. The primary transfer rolls 33 of the transfer device 30 shown in FIG. 1 transfer the toner images formed on the surfaces of the image carriers 21 for each color onto the transfer belt 31 at the primary transfer position T.

[0048] Thus, the sheet material P sent from the storage section 50 to the supply path 40 by the delivery roll 58 is handed over to a tip holding section 68 (see FIG. 3) of the chain gripper 66 and transported. The sheet material P transported by the chain gripper 66 is sent out toward the secondary transfer position NT. At the secondary transfer position NT, the sheet material P is sandwiched between the transfer belt 31 and the transfer cylinder 36 and transported, so that the toner image on the surface of the transfer belt 31 is transferred to the surface of the sheet material P.

[0049] Furthermore, the fixing device 100 fixes the toner image transferred onto the surface of the sheet material P onto the sheet material P, and the sheet material P transported by the chain gripper 66 is sent out to the discharge path 42. The sheet material P sent out to the discharge path 42 is discharged to the outside of the apparatus main body 10a.

[0050] (Main part configuration) Next, the main heating section 120 will be described. As shown in Fig. 6, the main heating section 120 includes a heating roll 130 that clamps the sheet material P conveyed by a chain gripper 66 (see Fig. 1) to fix a toner image onto the sheet material P, and a pressure cylinder 140 that is disposed opposite the heating roll 130. The chain 72 (see Fig. 3) that constitutes the chain gripper 66 is an example of a synchronizing member. The chain gripper 66 synchronizes the rotation of the pressure cylinder 140 with the rotation of the transfer cylinder 36. Here, synchronization means that the rotational motion of one acts on the rotational motion of the other.

[0051] Furthermore, as shown in FIG. 7 , the heating section 120 is equipped with an approach / separation mechanism 150 that moves the heating roll 130 closer to or farther from the pressure cylinder 140, and a suppression section 180 that suppresses the load torque generated on the pressure cylinder 140 by the approach / separation mechanism 150 moving the heating roll 130 closer to or farther from the pressure cylinder 140.

[0052] [Heating roll 130] 6, the heating roll 130 is disposed so as to contact the upwardly facing surface of the sheet member P being conveyed and extend in the device depth direction with its axial direction being the device depth direction. Support members 164 (see FIG. 7) that rotatably support the heating roll 130 are provided on both ends of the heating roll 130 in the device depth direction.

[0053] [Pressure cylinder 140] 6, the pressure cylinder 140 is disposed on the opposite side of the heating roll 130 with the sheet material P sandwiched therebetween, in contact with the downward surface of the conveyed sheet material P, and extends in the device depth direction with its axial direction being the device depth direction, and is driven to rotate. A recess 140a extending in the device depth direction is formed on the outer peripheral surface of the pressure cylinder 140. When the sheet material P passes between the pressure cylinder 140 and the heating roll 130, the leading end holding portion 68 that grips the leading end of the sheet material P is accommodated in this recess 140a.

[0054] 7, the pressure cylinder 140 is provided with a rotating shaft 142 and a pressure member (not shown) that presses the sheet member P toward the heating roll 130 via the rotating shaft 142.

[0055] [Approach and separation mechanism 150] As shown in FIG. 7, the approaching and separating mechanism 150 includes a cam mechanism 152 that rotates together with the pressure cylinder 140, and a cam follower mechanism 160 that is connected to the heating roll .

[0056] -Cam mechanism 152- A pair of cam mechanisms 152 are provided with the pressure cylinder 140 between them in the device depth direction, and are attached to the rotating shaft 142 of the pressure cylinder 140. The cam mechanism 152 includes a cam member 154 having a cam surface 156 formed on its outer periphery, and a support member 158 that extends radially of the rotating shaft 142, has the rotating shaft 142 attached to one end, and has the cam member 154 attached to the other end.

[0057] -Cam follower mechanism 160- The cam follower mechanism 160 includes a cam follower 162 whose rotation axis direction is the device depth direction, a support member 164 that rotatably supports the cam follower 162 and the heating roll 130, and a biasing member 166 that biases the cam follower 162 against the cam surface 156 of the cam member 154.

[0058] The cam follower 162 is arranged on one side of the heating roll 130 in the device width direction (left side in the figure), and the support member 164 extends so as to pass through the rotation axis of the cam follower 162 and the rotation axis of the heating roll 130 when viewed from the device depth direction.

[0059] The support member 164 is formed on a portion of the support member 164 opposite the cam follower 162 with the heating roll 130 therebetween, and is supported by a frame member (not shown) so as to be swingable about a rotation axis 164a whose axial direction is the depth direction of the device.

[0060] Moreover, the biasing member 166 is a compression coil spring extending in the vertical direction of the device, and presses the cam follower 162 against the cam surface 156 of the cam member 154. And, on the cam surface 156 of the cam member 154 described above, there are formed an introduction portion 156a that introduces the cam follower 162 into the cam surface 156, a lifting portion 156b that lifts the cam follower 162 guided by the introduction portion 156a, and a maintaining portion 156c that maintains the lifted state of the cam follower 162 lifted by the lifting portion 156b.

[0061] In this configuration, when the cam follower 162 is separated from the cam surface 156 in the circumferential direction of the pressure cylinder 140, the heating roll 130 is in contact with the pressure cylinder 140. When the pressure cylinder 140 rotates in the counterclockwise direction shown in Fig. 7, the cam follower 162 is guided to the introduction portion 156a of the cam surface 156 as shown in Fig. 7.

[0062] Furthermore, as a result of the cam member 154 rotating together with the pressure cylinder 140, as shown in Fig. 8(A), the lifting portion 156b of the cam surface 156 reaches the cam follower 162. As the lifting portion 156b reaches the cam follower 162, the cam follower 162 presses the lifting portion 156b of the cam surface 156.

[0063] When the cam follower 162 presses the lifting portion 156b of the cam surface 156, a load torque acts on the pressure cylinder 140. Specifically, a clockwise load torque acts on the pressure cylinder 140 while the pressure cylinder 140 is rotating counterclockwise (see arrow d1 in the figure). Then, when the cam follower 162 passes through the lifting portion 156b, the heating roll 130 separates from the pressure cylinder 140 before the heating roll 130 reaches the recessed portion 140a of the pressure cylinder 140.

[0064] Furthermore, as the cam member 154 rotates together with the pressure cylinder 140, the retaining portion 156c of the cam surface 156 reaches the cam follower 162, and the cam follower 162 passes through the retaining portion 156c. As the cam member 154 rotates together with the pressure cylinder 140, the terminal end of the retaining portion 156c of the cam surface 156 reaches the cam follower 162, as shown in FIG. 8(B).

[0065] As the cam follower 162 passes through the maintaining portion 156c, the recess 140a of the pressure cylinder 140 passes through the heating roll 130 in a state separated from the pressure cylinder 140. Then, as the cam follower 162 reaches the terminal end of the maintaining portion 156c of the cam surface 156, a load torque acts on the pressure cylinder 140. Specifically, a counterclockwise load torque further acts on the pressure cylinder 140 rotating in the counterclockwise direction (see arrow d2 in the figure).

[0066] Then, when the cam follower 162 passes through the maintaining portion 156c, the heating roll 130 comes into contact with the pressure cylinder 140, and the sheet member P is sandwiched between the heating roll 130 and the pressure cylinder 140, as shown in FIG. 8(C).

[0067] [Suppression part 180] As shown in FIG. 7, the suppression unit 180 includes a cam mechanism 182 that rotates together with the pressure cylinder 140, and a cam follower mechanism 190.

[0068] -Cam mechanism 182- A pair of cam mechanisms 182 are provided with pressure cylinder 140 between them in the device depth direction, and are attached to rotation shaft 142 of pressure cylinder 140. Cam mechanism 182 includes a cam member 184 having a cam surface 186 formed on its outer periphery. Cam member 184 is an example of another cam member.

[0069] When viewed from the device depth direction, the cam surface 186 on the opposite side of the rotation shaft 142 to the recess 140a of the pressure barrel 140 is uneven in the radial direction of the pressure barrel 140. The cam surface 186 other than the uneven portion is arc-shaped with the rotation shaft 142 as the center when viewed from the device depth direction.

[0070] -Cam follower mechanism 190- The cam follower mechanism 190 includes a cam follower 192 whose rotation axis direction is the device depth direction, and a biasing member 196 that biases the cam follower 192 against the cam surface 186 of the cam member 184. The cam follower 192 is an example of another cam follower.

[0071] The cam follower 192 is disposed on the opposite side of the cam follower 16 across the rotation shaft 142 of the pressure cylinder 140. Here, the opposite side of the cam follower 162 across the rotation shaft 142 means that the central angle α formed by the line segment a1 connecting the center of the rotation shaft 142 and the center of the cam follower 162 and the line segment a2 connecting the center of the rotation shaft 142 and the center of the cam follower 192 is 150 degrees or more and 210 degrees or less.

[0072] The biasing member 196 is a compression coil spring extending in the vertical direction of the device, and presses the cam follower 192 against the cam surface 186 of the cam member 184. A first offset portion 186a is formed on the cam surface 186 of the cam member 184 for applying a counterclockwise load torque to the pressure cylinder 140 to offset the clockwise load torque applied to the pressure cylinder 140. A second offset portion 186b is formed on the cam surface 186 next to the first offset portion 186a for applying a clockwise load torque to the pressure cylinder 140 to offset the counterclockwise load torque applied to the pressure cylinder 140. A third offset portion 186c is formed on the cam surface 186 next to the second offset portion 186b for applying a counterclockwise load torque to the pressure cylinder 140 to offset the clockwise load torque applied to the pressure cylinder 140.

[0073] In this configuration, as a result of the cam member 154 rotating together with the pressure barrel 140, the lifted portion 156b of the cam surface 156 reaches the cam follower 162, as shown in Fig. 8(A). Then, the cam follower 162 presses the lifted portion 156b of the cam surface 156, so that a clockwise load torque acts on the pressure barrel 140 rotating in the counterclockwise direction (part h1 in Fig. 9). Note that Fig. 9 shows a graph in which the horizontal axis represents the rotation angle of the pressure barrel 140 and the vertical axis represents the torque loaded on the pressure barrel 140.

[0074] Here, as the cam member 184 rotates together with the pressure barrel 140, the first counterbalancing portion 186a of the cam surface 186 reaches the cam follower 192. Then, the cam follower 192 presses the first counterbalancing portion 186a, so that a counterbalancing torque in the clockwise direction acts on the pressure barrel 140 (part s1 in FIG. 9). As a result, the load torque applied to the pressure barrel 140 is counterbalance by the counterbalancing torque.

[0075] Furthermore, as a result of the cam member 154 rotating together with the pressure barrel 140, as shown in Fig. 8(B), the end portion of the retaining portion 156c of the cam surface 156 reaches the cam follower 162. Then, the cam follower 162 presses the end portion of the retaining portion 156c, so that a counterclockwise load torque acts on the pressure barrel 140 rotating in the counterclockwise direction (part h2 in Fig. 9).

[0076] Here, as the cam member 184 rotates together with the pressure barrel 140, the second counterbalancing portion 186b of the cam surface 186 reaches the cam follower 192. Then, the cam follower 192 presses the second counterbalancing portion 186b, and a counterbalancing torque in the clockwise direction acts on the pressure barrel 140 (part s2 in FIG. 9). As a result, the load torque applied to the pressure barrel 140 is counterbalance by the counterbalancing torque.

[0077] Furthermore, as the cam member 154 rotates together with the pressure cylinder 140, as shown in Figure 8 (C), the heating roll 130 comes into contact with the pressure cylinder 140, causing the elastic layer of the heating roll 130 to elastically deform, resulting in a clockwise load torque acting on the pressure cylinder 140 rotating counterclockwise (part h3 in Figure 9).

[0078] Here, as the cam member 184 rotates together with the pressure barrel 140, the third counterbalancing portion 186c of the cam surface 186 reaches the cam follower 192. Then, the cam follower 192 presses the third counterbalancing portion 186c, so that a counterbalancing torque in the clockwise direction acts on the pressure barrel 140 (part s3 in FIG. 9). As a result, the load torque applied to the pressure barrel 140 is counterbalance by the counterbalancing torque.

[0079] (summary) As described above, in image forming apparatus 10, the load torque applied to pressure cylinder 140 by approach / separation mechanism 150 is offset by the offsetting torque applied to pressure cylinder 140 by suppression section 180. As a result, in a configuration in which the rotation of pressure cylinder 140 and the rotation of transfer cylinder 36 are synchronized, the fluctuation in the rotation speed of transfer cylinder 36 is suppressed compared to a case in which the fluctuation in the load torque applied to the pressure cylinder directly results in a fluctuation in the rotation speed of the pressure cylinder.

[0080] Moreover, in image forming apparatus 10, suppression section 180 is attached to rotation shaft 142 of pressure cylinder 140 and includes cam member 184 which rotates together with pressure cylinder 140, and cam follower 192 which is pressed against cam surface 186 of cam member 184. This allows the load torque to be reduced with a simpler configuration than when an offsetting torque is electrically applied to the rotation shaft of the pressure cylinder in order to reduce the load torque generated in the pressure cylinder.

[0081] Furthermore, in image forming apparatus 10, cam follower 192 is disposed on the opposite side of cam follower 162 across rotation shaft 142 of pressure cylinder 140 when viewed from the device depth direction. This suppresses deflection of rotation shaft 142 compared to when cam follower 192 and cam follower 162 are disposed on the same side of rotation shaft 142.

[0082] <Second embodiment> An example of an image forming apparatus according to a second embodiment of the present disclosure will be described with reference to Fig. 10. Note that, regarding the second embodiment, differences from the first embodiment will be mainly described.

[0083] (Main part configuration) As shown in FIG. 10, the main heating section 320 of the image forming apparatus 210 according to the second embodiment includes a heating roll 130 that sandwiches the transported sheet material P to fix a toner image onto the sheet material P, and a pressure cylinder 140.

[0084] Furthermore, the heating section 320 is equipped with an approach / separation mechanism 150 for moving the heating roll 130 closer to or farther from the pressure cylinder 140, and a suppression section 380 for suppressing fluctuations in the load torque generated in the pressure cylinder 140 by the approach / separation mechanism 150 moving the heating roll 130 closer to or farther from the pressure cylinder 140.

[0085] [Suppression part 380] 10, the suppression unit 380 includes a first gear 382 that rotates together with the pressure cylinder 140, and a second gear 384 that meshes with the first gear 382. The suppression unit 380 further includes a cam mechanism 392 that is attached to a rotation shaft 384a of the second gear 384 and rotates together with the rotation shaft 384a of the second gear 384, and a cam follower mechanism 400 that is pressed against a cam surface 396 of a cam member 394 of the cam mechanism 392.

[0086] -First gear 382, ​​second gear 384- The first gear 382 and the second gear 384 are provided as a pair with the pressure cylinder 140 therebetween in the device depth direction.

[0087] The first gear 382 is attached to the rotating shaft 142 of the pressure cylinder 140 and rotates together with the pressure cylinder 140. The first gear 382 has a smaller diameter than the rotating shaft 142. The second gear 384 is disposed on one side of the first gear 382 in the device width direction and meshes with the first gear 382. The reduction ratio achieved by the meshing of the second gear 384 and the first gear 382 is 2x. 2x is an example of an integer multiple of 2 or more.

[0088] -Cam mechanism 392- The cam mechanism 392 is provided as a pair with the pressure cylinder 140 between them in the device depth direction. The cam mechanism 392 includes a cam member 394 having a cam surface 396 formed on its outer periphery. The cam member 394 is an example of another cam member.

[0089] When viewed from the device depth direction, the cam surface 396 on both sides of the rotation shaft 384a is uneven. The cam surface 396 other than the uneven parts is a circular hole centered on the rotation shaft 384a when viewed from the device depth direction.

[0090] -Cam follower mechanism 400- The cam follower mechanisms 400 are provided as a pair with the pressure cylinder 140 between them in the device depth direction. The cam follower mechanism 400 includes a cam follower 402 whose rotation axis direction is the device depth direction, and a biasing member 406 that biases the cam follower 402 against the cam surface 396 of the cam member 394. The cam follower 402 is an example of another cam follower.

[0091] The biasing member 406 is a compression coil spring extending in the vertical direction of the device, and presses the cam follower 402 against the cam surface 396 of the cam member 394. A first offset portion 396a is formed on the cam surface 396 of the cam member 394 for applying a counterclockwise load torque to the pressure cylinder 140 to offset the clockwise load torque applied to the pressure cylinder 140. A second offset portion 396b is formed on the cam surface 396 next to the first offset portion 396a for applying a clockwise load torque to the pressure cylinder 140 to offset the counterclockwise load torque applied to the pressure cylinder 140. A third offset portion 396c is formed on the cam surface 396 next to the second offset portion 396b for applying a counterclockwise load torque to the pressure cylinder 140 to offset the clockwise load torque applied to the pressure cylinder 140.

[0092] (summary) 10, in the image forming apparatus 210, the suppression section 380 includes a first gear 382 that rotates together with the pressure cylinder 140, and a second gear 384 that meshes with the first gear 382 and has a reduction ratio that is twice that of the first gear 382. This makes the pressing force (biasing force) applied to the cam follower 402 weaker than when the cam member is attached to the rotation shaft of the pressure roll.

[0093] Furthermore, in the image forming apparatus 210, the suppression section 380 includes two cam followers 402. As a result, the pressing force (pressing force) applied to the cam follower 402 is weaker than in the case where there is one cam follower.

[0094] Although the present disclosure has been described in detail with respect to a specific embodiment, it is clear to those skilled in the art that the present disclosure is not limited to the embodiment, and various other embodiments are possible within the scope of the present disclosure. For example, in the above embodiment, the suppressing unit 180, 380 includes the cam member 184, 394 and the cam follower 192, 402, but the load torque may be reduced by electrically applying torque to the rotating shaft of the pressure cylinder. However, in this case, the effect of including the cam member and the cam follower is not achieved.

[0095] In addition, in the above-described first embodiment, when viewed from the direction of the rotation axis of the pressure cylinder 140, the cam follower 192 is disposed on the opposite side to the cam follower 162 across the pressure roll rotation shaft 142, but the cam follower 192 may be disposed on the same side of the pressure roll rotation shaft 142. However, in this case, the effect achieved by disposing the cam follower 192 on the opposite side to the cam follower 162 is not achieved.

[0096] In addition, in the second embodiment described above, the reduction ratio of the second gear 384 to the first gear 382 is 2, but this reduction ratio may be any integer multiple of 2 or more, and may be 3, 4, etc.

[0097] In addition, in the above second embodiment, two cam followers 402 are provided, which is the reduction ratio of second gear 384 to first gear 382, ​​but one cam follower may be provided. In this case, however, the effect of providing two cam followers 402, which is the reduction ratio of second gear 384 to first gear 382, ​​will not be achieved.

[0098] In the second embodiment, two cam followers 402 are provided because the reduction ratio of the second gear 384 to the first gear 382 is two, but if the reduction ratio of the second gear to the first gear is N, N cam followers 402 may be provided. Note that a number other than N may be used, but the effect achieved by providing N cam followers will not be achieved.

[0099] (((1))) a transfer cylinder that rotates and pinches the conveyed recording medium between itself and a transfer member to which an image has been transferred, thereby transferring the image onto the recording medium; a heating roll disposed downstream of the transfer cylinder in a conveying direction of the recording medium and configured to heat the conveyed recording medium while rotating; a pressure cylinder that is disposed opposite the heating roll and rotates in synchronization with the rotation of the transfer cylinder and presses the recording medium being conveyed toward the heating roll; a cam member that rotates together with the pressure cylinder and a cam follower that is connected to the heat roll and is pressed against a cam surface of the cam member, the cam member being connected to the heat roll and configured to move the heat roll toward and away from the pressure cylinder; a suppression unit that suppresses a load torque generated on the pressure cylinder by the approaching and separating mechanism moving the heating roll toward and away from the pressure cylinder; An image forming apparatus comprising:

[0100] (((2))) The suppression portion includes another cam member attached to the pressure cylinder and rotating together with the pressure cylinder, and another cam follower pressed against another cam surface of the other cam member. The image forming apparatus according to (((1))).

[0101] (((3))) When viewed from the rotation axis direction of the pressure cylinder, the other cam follower is disposed on the opposite side to the cam follower across the rotation axis of the pressure cylinder. The image forming apparatus according to (((2))).

[0102] (((4))) The suppression unit includes a first gear attached to the pressure cylinder and rotating together with the pressure cylinder, a second gear meshing with the first gear to provide a reduction ratio that is an integer multiple of 2 or more, another cam member attached to the second gear and rotating together with the second gear, and another cam follower pressed against another cam surface of the other cam member. The image forming apparatus according to (((1))).

[0103] (((5))) The other cam followers are provided in N times the number of the other cam followers. The image forming apparatus according to (((4))).

[0104] According to the image forming apparatus of (((1))), in a configuration in which the rotation of the pressure cylinder and the rotation of the transfer cylinder are synchronized, the fluctuations in the rotation speed of the transfer cylinder can be suppressed compared to a case in which the fluctuations in the load torque generated in the pressure cylinder directly result in fluctuations in the rotation speed of the pressure cylinder.

[0105] According to the image forming apparatus of (((2))), the load torque generated in the pressure cylinder can be reduced with a simple configuration, compared to the case where a torque is electrically applied to the rotating shaft of the pressure cylinder in order to reduce the load torque.

[0106] According to the image forming apparatus of (((3))), when viewed from the direction of the rotation axis of the pressure drum, bending of the rotation axis can be suppressed compared to a case in which the cam follower and another cam follower are arranged on the same side of the rotation axis.

[0107] According to the image forming apparatus of (((4))), the pressing force applied to the other cam follower can be reduced to an integer fraction as compared to the case where the other cam member is attached to the pressure cylinder.

[0108] According to the image forming apparatus of (((5))), the pressing force applied to the other cam follower can be made weaker than when there is one other cam follower. [Explanation of symbols]

[0109] 10 Image forming device 36 Transfer cylinder 72 Chain (an example of a synchronizing component) 130 Heating Roll 142 Rotational Axis 150 Approach and Separation Mechanism 154 Cam member 156 Cam surface 162 Cam follower 180 Suppression part 184 Cam parts (other cam parts) 186 Cam surface 192 Cam Follower (Other Cam Follower) 382 First Gear 384 Second Gear 384a Rotating shaft 394 Cam parts (other cam parts) 396 Cam surface 402 Cam Follower (Other Cam Follower)

Claims

1. a transfer cylinder that rotates and sandwiches the conveyed recording medium between itself and a transfer member onto which an image has been transferred, thereby transferring the image onto the recording medium; a heating roll disposed downstream of the transfer cylinder in a conveying direction of the recording medium and configured to heat the conveyed recording medium while rotating; a pressure cylinder that is disposed opposite the heating roll and rotates in synchronization with the rotation of the transfer cylinder and presses the recording medium being conveyed toward the heating roll; a cam member that rotates together with the pressure cylinder and a cam follower that is connected to the heat roll and is pressed against a cam surface of the cam member, the cam member being connected to the heat roll and configured to move the heat roll toward and away from the pressure cylinder; a suppression unit that suppresses a load torque generated on the pressure cylinder by the approaching and separating mechanism moving the heating roll toward and away from the pressure cylinder; An image forming apparatus comprising:

2. The suppression portion includes another cam member attached to the pressure cylinder and rotating together with the pressure cylinder, and another cam follower pressed against another cam surface of the other cam member. The image forming apparatus according to claim 1 .

3. When viewed from the rotation axis direction of the pressure cylinder, the other cam follower is disposed on the opposite side to the cam follower across the rotation axis of the pressure cylinder. The image forming apparatus according to claim 2 .

4. the suppression unit includes a first gear attached to the pressure cylinder and rotating together with the pressure cylinder, a second gear meshing with the first gear to provide a reduction ratio that is an integer multiple of 2 or more, another cam member attached to the second gear and rotating together with the second gear, and another cam follower pressed against another cam surface of the other cam member. The image forming apparatus according to claim 1 .

5. The other cam follower is provided in N-fold case, The image forming apparatus according to claim 4 .

Images