Fixing device and image forming apparatus

Abstract

To provide a recording medium conveying device, a fixing device and an image forming device which, when a recording medium is gripped and conveyed, can prevent wrinkles of the recording medium caused by gripping the recording medium, and can prevent members from coming into contact with each other.SOLUTION: A recording medium conveying device comprises: first means 62 to be rotated; second means 56 for holding and conveying a recording medium; gripping means 60 for gripping the recording medium; a peeling member 64; and control means for separating the first means 62 and the second means 56 from each other in a first section, and opening the gripping means 60 to release the recording medium until the first means 62 and the second means 56 come into next contact with each other, and after that, for controlling contact / separation between the first means 62 and the second means 56 and opening / closing of the gripping means 60 so as to more largely open the gripping means 60 than in the first section in a second section before the recording medium reaches the peeling member 64.SELECTED DRAWING: Figure 12

Description

[Technical Field]

[0001] The present invention relates to a recording medium transport device, a fixing device, and an image forming apparatus. [Background technology]

[0002] Patent Document 1 discloses a fixing device that includes a fixing roll pair consisting of a first fixing roll and a second fixing roll, at least one of which is a heating roll and the surface layer of at least one of the fixing rolls is replaceable, an adhering means having an adhering member, a charging means that charges at least one of the recording medium and the adhering means, and a fixing means that physically fixes the leading end of the recording medium in the transport direction to the adhering means with a gripping portion, and that fixes the recording medium to the adhering member by electrostatically adhering the recording medium and the fixing means, and then clamps the recording medium together with the adhering means between the fixing roll pair and transports it, thereby fixing an image. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-259223 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention is directed to a method for conveying a recording medium by gripping the recording medium. 、 Preventing contact between parts can An object of the present invention is to provide a fixing device and an image forming apparatus. [Means for solving the problem]

[0005] A first aspect is a recording medium transport device having a rotating first means, a rotating second means that clamps and transports a recording medium in a clamping area formed between the first means, gripping means that grips the recording medium, a peeling member that peels the recording medium that has passed through the clamping area from the first means or the second means, and a control means that controls the contact and separation of the first means and the second means and the opening and closing of the gripping means so that, in a first section in which the gripping means passes between the first means and the second means, the first means and the second means are separated, and then the first means and the second means come into contact, and the gripping means opens to release the recording medium, and then, in a second section before the recording medium reaches the peeling member, the gripping means opens wider than in the first section.

[0006] A second aspect is a recording medium transport device according to the first aspect, in which the gripping means has a fixed claw and a movable claw that contacts and moves away from the fixed claw, and the movable claw is opened so as not to hit the first means or the second means.

[0007] A third aspect is a recording medium transport device according to the first aspect, in which the gripping means has a fixed claw and a movable claw that contacts and moves away from the fixed claw, and in the first section, the movable claw is opened within the separation range of the first means and the second means.

[0008] A fourth aspect is a recording medium conveying device according to the first aspect, in which the gripping means has a fixed claw and a movable claw that contacts and moves away from the fixed claw, and in the second section, the recording medium is opened so that it does not hit the movable claw when peeling off the recording medium.

[0009] A fifth aspect is a recording medium conveying device according to the first aspect, in which the gripping means has a fixed claw and a movable claw that contacts and moves away from the fixed claw, and in the second section, is opened to a range greater than the movement range of the recording medium when peeling off the recording medium.

[0010] A sixth aspect is the recording medium transport device according to any one of the first to fifth aspects, wherein the peeling member moves in a direction to peel the recording medium from the first means or the second means.

[0011] A seventh aspect is the recording medium transport device according to the sixth aspect, wherein the control means further controls the movement of the peeling member.

[0012] An eighth aspect is a fixing device comprising: a rotating heating member; a rotating fixing cylinder that applies pressure to a recording medium by pinching the recording medium in a pinch region formed between the heating member and the fixing cylinder; a gripping means that grips the recording medium; a peeling member that peels the recording medium from the fixing cylinder after passing through the pinch region; and a control means that controls the contact and separation of the heating member with respect to the fixing cylinder and the opening and closing of the gripping means so that, in a first section in which the gripping means passes between the heating member and the fixing cylinder, the heating member is separated from the fixing cylinder, and the gripping means is opened to release the recording medium until the heating member is brought into contact with the fixing cylinder, and then, in a second section until the recording medium reaches the peeling member, the gripping means is opened wider than in the first section.

[0013] A ninth aspect is the fixing device according to the eighth aspect, wherein the control means is configured as a cam mechanism that is actuated by rotation of the fixing cylinder.

[0014] A tenth aspect is an image forming apparatus having an image forming unit that forms a developer image on a recording medium, and a fixing device that fixes the developer image formed on the recording medium by the image forming unit to the recording medium, wherein the fixing device has a rotating heating member, a rotating fixing cylinder that clamps the recording medium in a clamping area formed between the heating member and the fixing cylinder and applies recording medium pressure, a gripping means that grips the recording medium, a peeling member that peels the recording medium that has passed through the clamping area from the fixing cylinder, and a control means that controls the contact and separation of the heating member with the fixing cylinder and the opening and closing of the gripping means so that in a first section in which the gripping means passes between the heating member and the fixing cylinder, the gripping means is separated from the fixing cylinder and then the gripping means is opened to release the recording medium until the heating member contacts the fixing cylinder, and then in a second section before the recording medium reaches the peeling member, the gripping means is opened wider than in the first section. [Effects of the Invention]

[0015] According to the first, eighth or tenth aspect, when a recording medium is gripped and transported, it is possible to avoid wrinkling of the recording medium due to gripping the recording medium and to prevent contact between members.

[0016] According to the second or third aspect, the movable claw constituting the gripping means can be prevented from hitting the first means or the second means.

[0017] According to the fourth or fifth aspect, when the recording medium is peeled off, it is possible to prevent the recording medium from coming into contact with the movable claw.

[0018] According to the sixth aspect, the peeling of the recording medium can be promoted.

[0019] According to the seventh aspect, it is possible to collectively control the contact and separation between the first means and the second means, the opening and closing of the gripping means, and the movement of the peeling member.

[0020] According to the ninth aspect, the contact and separation between the heating member and the fixing cylinder and the opening and closing of the gripping means can be controlled in accordance with the rotation of the fixing cylinder. [Brief explanation of the drawings]

[0021] [Figure 1] 1 is a front view showing an image forming apparatus according to an embodiment of the present invention; [Figure 2] 1 is a front view of an image forming unit used in an image forming apparatus according to an exemplary embodiment of the present invention. [Figure 3] 2 is a perspective view showing a state in which a recording medium is gripped by a gripper in the image forming apparatus according to the embodiment of the present invention; FIG. [Figure 4] 1 is a perspective view showing a fixing device and its peripheral structure in an image forming apparatus according to an embodiment of the present invention; [Figure 5] FIG. 2 is a plan view showing a gripper and a peeling member in the image forming apparatus according to the exemplary embodiment of the present invention. [Figure 6] 10 is a front view showing a cam mechanism that controls the driving of a heating member and a movable claw in an image forming apparatus according to an embodiment of the present invention. FIG. [Figure 7] 4 is a front view showing a cam mechanism that controls the driving of a peeling member in the image forming apparatus according to the exemplary embodiment of the present invention. FIG. [Figure 8] 5 is a timing chart showing the movements of the heating member, the peeling member, and the movable claw relative to the rotation angle of the fixing cylinder in the image forming apparatus according to the embodiment of the present invention. [Figure 9] 10 is an enlarged front view of the fixing device showing a state when the movable claw starts to open in the image forming apparatus according to the exemplary embodiment of the present invention; FIG. [Figure 10] 3 is an enlarged front view of the fixing device in the image forming apparatus according to the exemplary embodiment of the present invention, showing a state in which the heating member is in contact with the fixing cylinder. FIG. [Figure 11] 1 is an enlarged front view of a fixing device in an image forming apparatus according to an embodiment of the present invention, illustrating a state in which a pinch region is formed between a heating member and a fixing cylinder. [Figure 12]4 is an enlarged front view of the fixing device in the image forming apparatus according to the exemplary embodiment of the present invention, showing a state before the movable claw is fully opened. FIG. [Figure 13] 3 is an enlarged front view of the fixing device in the image forming apparatus according to the exemplary embodiment of the present invention, showing a state in which the movable claw is fully opened. FIG. [Figure 14] 10 is an enlarged side view of the fixing device when the peeling member starts to rise in the image forming apparatus according to the exemplary embodiment of the present invention; FIG. [Figure 15] 10 is an enlarged front view of the fixing device showing a state when the peeling member has entered the leading edge of the recording medium in the image forming apparatus according to the exemplary embodiment of the present invention; FIG. [Figure 16] 10 is an enlarged front view of the fixing device showing a state when the peeling member flips up the leading edge of the recording medium in the image forming apparatus according to the exemplary embodiment of the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] FIG. 1 shows an image forming apparatus 10 according to this embodiment.

[0023] The image forming apparatus 10 includes a recording medium storage unit 12, a recording medium transport unit 14, an image forming unit 16, a recording medium transport device 18, a fixing device 20, a cooling unit 22, and a recording medium ejection unit 24.

[0024] There are, for example, two recording medium housing units 12, each housing a recording medium. Furthermore, the recording medium transport unit 14 has a feed member 26 provided above the recording medium housing unit 12, and this feed member 26 feeds the recording medium out of the recording medium housing unit 12. Furthermore, the recording medium fed out from this feed member 26 is transported by a transport member 28 and passed to the recording medium transport device 18.

[0025] The image forming section 16 includes a developer image forming section 30 and an intermediate transfer unit 32 . The developer image forming section 30 is provided with a plurality of image forming units 34 for forming toner layers of each color. In this embodiment, a total of four image forming units 34 are provided, one for each color: a yellow image forming unit 34Y, a magenta image forming unit 34M, a cyan image forming unit 34C, and a black image forming unit 34K.

[0026] Yellow (Y), magenta (M), cyan (C), and black (K) are the basic colors for outputting a color image. In the following description, when it is not necessary to distinguish between the colors of each image forming unit 34, they will simply be referred to as "image forming unit 34," and the symbols Y, M, C, and K representing the image forming units corresponding to each color may be omitted as appropriate.

[0027] The image forming units 34 are basically configured in the same manner, except for the type of toner used. As shown in Fig. 2, the image forming unit 34 includes a cylindrical photoconductor 36 that rotates in the direction of arrow A, and a charger 38 that charges the photoconductor 36. The image forming unit 34 also includes an exposure device 40 that irradiates the charged photoconductor 36 with exposure light to form an electrostatic latent image, and a developing device 42 that develops the electrostatic latent image into an image formed by a toner layer using a developer containing toner.

[0028] The photoconductors 36 for each color are configured to be able to come into contact with the outer peripheral surface of an intermediate transfer belt 44, which will be described later. In addition, the image forming units 34 corresponding to yellow, magenta, cyan, and black are arranged side by side from the upstream side to the downstream side in the rotation direction of the intermediate transfer belt 44.

[0029] In this embodiment, an example is given of a configuration in which an image is recorded using four colors of toner, CMYK, but this is not limiting, and the toner colors and their combinations may be changed, and for example, light color toners, light toners such as light cyan and light magenta, dark toners, special color toners, etc. may be added as needed. In addition, the arrangement order of the image forming units 34 for each color is not limited to the order shown in the figure.

[0030] The intermediate transfer unit 32 has an endless intermediate transfer belt 44 that rotates in direction B. The intermediate transfer belt 44 is wound around a plurality of support rolls 46 and a primary transfer roll 48 that is disposed opposite the image forming unit 34 for each color, and its position is determined. One of the plurality of support rolls 46 has the function of rotating the intermediate transfer belt 44 in the direction of arrow B using the power of a motor (not shown). By rotating in the direction of arrow B, the intermediate transfer belt 44 transports the primarily transferred image to the secondary transfer position.

[0031] A voltage is applied to the primary transfer roll 48 by a power supply unit (not shown). This voltage is a primary transfer voltage for primarily transferring the developer image formed on the photoreceptor 36 onto the intermediate transfer belt 44 between the photoreceptor 36 and the primary transfer roll 48.

[0032] A secondary transfer unit 52 made up of a corotron is provided at a position facing the transfer cylinder 50 across the intermediate transfer belt 44. The developer image formed on the intermediate transfer belt 44 is transferred to a recording medium by this secondary transfer unit.

[0033] In this embodiment, the recording medium transport device 18 has a chain 54 as a transport means. The chains 54 are provided in pairs in the front-to-rear direction of the device, and are stretched over sprockets (sprocket 58 provided on the fixing cylinder 56 is shown in FIG. 4) that are provided on both axial sides of the transfer cylinder 50 and the fixing cylinder 56, and a sprocket 58 that is provided on the recording medium transport section 14 side. When either of these sprockets rotates, the chain 54 is rotated in the C direction.

[0034] The chain 54 is also provided with a plurality of grippers 60 as gripping means. These grippers 60 grip the leading edge of the recording medium, and transport the recording medium in a clamped state as the chain 54 moves. The leading edge of the recording medium transported from the recording medium transport unit 14 is clamped by the grippers 60, and at the secondary transfer position, the developer image formed in the image forming unit 16 is transferred onto the recording medium, and the recording medium passes through the fixing device 20, where the developer image is fixed.

[0035] Fixing device 20 has a heating member 62 constituting first means and a fixing cylinder 56 constituting second means. Fixing device 20 clamps the recording medium in a pinch region formed between heating member 62 and fixing cylinder 56, and fixes the developer image to the recording medium by heat and pressure while transporting the recording medium. Fixing device 20 also has a peeling member 64 on the outlet side. This peeling member 64 peels the recording medium from fixing cylinder 56, and the peeled recording medium is transported and cooled by transport members 66, 66 of cooling section 22 and discharged to recording medium discharge section 24. When the heating member 62 is referred to as the first means and the fixing cylinder as the second means, it does not refer to the member itself but includes accompanying members such as a rotating shaft.

[0036] As shown in Fig. 3, the gripper 60 has a fixed claw 68 and a movable claw 70 that comes into contact with and separates from the fixed claw 68. Both ends of the fixed claw 68 are fixed to the chain 54. A large number of movable claws 70 are provided toward the depth direction of the image forming apparatus. These large number of movable claws 70 are fixed to movable claw drive shafts 72 and driven via these movable claw drive shafts 72. The leading edge of the recording medium is sandwiched between the fixed claw 68 and the movable claw 70, and in this sandwiched state the recording medium is transported in direction D.

[0037] 4, a fixing cylinder rotation shaft 74 is provided at the center of each end of the fixing cylinder 56, and the fixing cylinder 56 and sprocket 58 rotate in the direction E around this fixing cylinder rotation shaft 74. The fixing cylinder 56 is also formed with a recess 76 extending in the depth direction. The gripper 60 is housed in this recess 76. As the fixing cylinder 56 rotates in the direction E, the gripper 60, while housed in the recess 76, passes between the heating element 62 and the fixing cylinder 56. A heating element rotation shaft 78 is provided at the center of each end of the heating element 62, and the heating element 62 rotates in the opposite direction to the fixing cylinder 56 around this heating element rotation shaft 78. A heat source 80 is provided within the heating element 62.

[0038] As shown in FIG. 5 , the peeling member 64 is integrally formed with a peeling section 82 and a guide section 84 provided downstream of the peeling section 82 in the conveying direction. A large number of peeling sections 82 are formed toward the back of the image forming apparatus. A groove 86 is formed between each peeling section 82 and the peeling section 82 adjacent to it. The movable claw 70 of the gripper 60 is inserted into this groove 86. Furthermore, movable claw biasing members 88 are wound around both sides of the movable claw drive shaft 72. The movable claw biasing members 88 bias the movable claw 70 so that the movable claw 70 is pressed against the fixed claw 68. Furthermore, chain fixing sections 90 are provided on both sides of the fixed claw 68, and the fixed claw 68 is fixed to the chain 54 via the chain fixing sections 90.

[0039] 6, the heating element rotation shaft 78 is fitted into a support groove 94 formed in a first arm member 92. The first arm member 92 is supported at one end thereof on a first swing shaft 96 so as to be able to swing freely. A heating element cam follower 98 is provided at the other end of the first arm member 92. In addition, the first arm member 92 is provided with a heating member biasing member (not shown) that presses the heating member 62 against the fixing cylinder 56 so that a sandwiched area is formed between the heating member 62 and the fixing cylinder 56.

[0040] The heating member cam 100 is fixed to the outer periphery of the fixing cylinder 56 and rotates together with the fixing cylinder 56. The cam surface of the heating member cam 100 contacts the heating member cam follower 98 within a predetermined angular range. As the heating member cam follower 98 follows the heating member cam 100, the heating member 62 oscillates around the first oscillation shaft 96, and the heating member 62 is controlled to contact and separate from the fixing cylinder 56.

[0041] Furthermore, a movable claw cam 102 is provided around the fixing cylinder rotation shaft 74. This movable claw cam 102 is disposed coaxially with the fixing cylinder 56, but does not rotate with the fixing cylinder 56 and is fixed to the image forming apparatus main body. Meanwhile, a second arm member 104 is connected to the movable claw drive shaft 72, and a movable claw cam follower 106 is provided on the other end of this second arm member 104. The cam surface of the movable claw cam 102 contacts the movable claw cam follower 106 within a predetermined angular range. The movable claw 70 is controlled to contact and separate from the fixed claw 68 as the movable claw cam follower 106 follows the movable claw cam 102.

[0042] 7, the peeling member 64 is fixed to one end of a third arm member 108. The third arm member 108 is supported so as to be able to freely swing about a second swing shaft 110. A peeling member cam follower 112 is provided at the other end of the third arm member 108. The third arm member 108 is provided with a peeling member biasing member (not shown) that biases the peeling member 64 in a direction away from the fixing cylinder 56.

[0043] The peeling member cam 114 is fixed to the outer periphery of the fixing cylinder 56 beside the heating member cam 100 and rotates together with the fixing cylinder 56. The cam surface of this peeling member cam 114 contacts the peeling member cam follower 112 within a predetermined angular range. As the peeling member cam follower 112 follows the peeling member cam 114, the third arm member 108 swings about the second swing shaft 110, and the movement of the peeling member 64 is controlled so that the tip of the peeling member 64 enters the recessed portion 76 from a position away from the outer periphery of the fixing cylinder 56 and then moves away from the recessed portion 76 beyond the outer periphery of the fixing cylinder 56.

[0044] 8 shows a timing chart illustrating the movement control of the heating member 62, the peeling member 64, and the movable claw 70. The horizontal axis represents the rotation angle of the fixing cylinder 56, and the vertical axis represents the position of the heating member 62, the tip position of the peeling member 64, and the opening amount of the movable claw 70. O represents the reference position.

[0045] First, at angle a, the heating member cam follower 98 follows the cam surface of the heating member cam 100, causing the heating member 62 to start rising (moving in a direction away from the fixing cylinder 56). Next, at angle b, the peeling member cam follower 112 follows the peeling member cam 114, causing the peeling member 64 to start descending (moving in a direction in which the tip of the peeling member 64 enters the recess 76).

[0046] Further, at angle c, the heating member 62 descends (the fixing cylinder 56 to Furthermore, at an angle d immediately after the heating member 62 starts to descend, the movable claw cam follower 106 follows the movable claw cam 102, causing the movable claw 70 to open (the movable claw 70 moves in a direction away from the fixed claw 68).

[0047] FIG. 9 shows the state when the movable claw 70 begins to open. The heating member 62 is separated from the fixing cylinder 56. The peeling member 64 moves from a state where the tip of the peeling member 64 is outside the outer diameter of the fixing cylinder 56 (shown by a two-dot chain line) to a state where the tip of the peeling member 64 is inserted into the recess 76 of the fixing cylinder 56 (shown by a solid line). The movable claw cam follower 106 also begins to climb from the first surface 102a formed on the movable claw cam 102 to a second surface 102b that is higher than the first surface. When the movable claw cam follower 106 begins to climb onto the second surface 102b of the movable claw cam 102, the movable claw drive shaft 72 rotates counterclockwise, and the movable claw 70 begins to open. This releases the leading edge of the recording medium that was gripped between the movable claw 70 and the fixed claw 68.

[0048] In FIG. 10, as the fixing cylinder 56 continues to rotate, the heating member 62 comes into contact with the fixing cylinder 56, as shown in FIG. 10. As the fixing cylinder 56 continues to rotate, the heating member 62 is pressed into the fixing cylinder 56, forming a pinch region, as shown in FIG. 11. When a pinch region is formed between the heating member 62 and the fixing cylinder 56, the movable claw cam follower 106 starts to ride up the movable claw cam 102 from the second surface 102b to the third surface 102c, which is higher than the second surface 102b. The movable claw cam follower 106 stops the movable claw cam 102 from riding up onto the third surface 102c2. start Then, the movable claw drive shaft 72 rotates counterclockwise, and the movable claw 70 moves so as to open even wider.

[0049] That is, as shown in FIG. 8, at angle e, the movable claw 70 moves from the open state of the movable claw 70 at angle d to a state where the movable claw 70 is opened widely.

[0050] 12 shows the state before the movable claw 70 is fully opened. Because the leading edge of the recording medium is released, there is a risk that the recording medium may jump up, but in this state, the leading edge of the movable claw 70 is within the range of movement of the leading edge of the recording medium, and the movable claw 70 prevents the recording medium from jumping up.

[0051] 13 shows the movable claw 70 in its fully open state. The tip of the peeling member 64 approaches the leading edge of the recording medium while inserted into the recess 76 of the fixing cylinder 56. Also, because the movable claw 70 is fully open, the tip of the movable claw 70 is out of the range of movement of the leading edge of the recording medium, and the peeling member 64 is ready to flip up the leading edge of the recording medium.

[0052] Returning to FIG. 8, at angle f while the movable claw 70 is at its widest position, the peeling member 64 begins to rise. When the peeling member 64 begins to rise, the tip of the peeling member 64 approaches the leading edge of the recording medium as it rises, as shown in FIG. 14. As the fixing cylinder 56 continues to rotate, the tip of the peeling member 64 enters behind the leading edge of the recording medium, as shown in FIG. 15. Then, as shown in FIG. 16, the tip of the peeling member 64 moves outward from the outer periphery of the fixing cylinder 56, and the leading edge of the recording medium is lifted up by the tip of the peeling member 64, and the recording medium is guided to the upper surface of the peeling member 64.

[0053] In the above embodiment, the contact and separation of the heating member 62 with respect to the fixing cylinder 56, the opening and closing of the movable claws 70, and the movement of the peeling member 64 are controlled by a cam or cam follower that rotates around the fixing cylinder rotation shaft 74, but the present invention is not limited to this, and these may also be controlled by other members that rotate in synchronization with the fixing cylinder 56. Furthermore, the present invention is not limited to control using a cam mechanism as in the above embodiment, and may also be electrically controlled using a motor or the like.

[0054] The configuration of the image forming apparatus is not limited to that of the above embodiment, and may be, for example, an inkjet recording apparatus, or may have various other configurations. Furthermore, the present invention may be embodied in various forms without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0055] 10 Image forming device 12 Recording medium storage section 14 Recording medium transport unit 16 Image forming unit 18 Recording medium transport device 20 Fixing device 22 Cooling section 24 Recording medium ejection section 26 Delivery member 28 Transporting member 30 Developer image forming unit 32 Intermediate transfer unit 34 Image forming unit 36 Photoreceptor 38 Charger 40 Exposure equipment 42 Developing device 44 Intermediate transfer belt 46 Support Roll 48 Primary transfer roll 50 Transfer cylinder 52 Secondary transfer unit 54 Chain 56 Fixing body 58 sprocket 60 Gripper 62 Heating element 64 Peeling member 66 Transport member 68 Fixed claw 70 Movable claw 72 Movable claw drive shaft 74 Fixing cylinder rotation axis 76 Recess 78 Heating member rotation axis 80 Heating source 82 Peeling part 84 Information Department 86 Groove 88 Movable claw biasing member 90 Chain fixing part 92 First arm member 94 Support groove 96 Swing axis 98 Cam follower for heating element 100 Cam for heating element 102 Movable claw cam 102a Front page 102b Second side 102c Third side 104 Second arm member 106 Movable claw cam follower 106 Movable cam follower 108 Third Arm 110 Swing axis 112 Cam follower for peeling member 114 Cam for peeling member

Claims

1. a rotating heating element; a cylindrical fixing drum that is disposed with its rotation axis oriented in the depth direction and that rotates, and that has a recessed portion formed on its outer circumferential surface that extends in the depth direction, and that applies pressure to the recording medium by clamping the recording medium in a clamping region formed between the fixing drum and the heating member; a gripping means for conveying the recording medium while gripping the leading edge thereof, and for passing the recording medium between the heating member and the fixing cylinder while being accommodated in the recessed portion as the fixing cylinder rotates; a peeling member that peels the recording medium that has passed through the pinch area from the fixing cylinder; and a cam mechanism actuated by the rotation of the fixing cylinder that controls the contact and separation of the heating member with respect to the fixing cylinder, the movement of the peeling member, and the opening and closing of the gripping means, so that the recording medium is peeled off from the fixing cylinder by moving the heating member in a direction away from the fixing cylinder at the timing when the gripping means passes between the heating member and the fixing cylinder, then moving the peeling member in a direction where the tip of the peeling member enters the recess from a position away from the outer periphery of the fixing cylinder, then starting the movement of the heating member in a direction where the heating member contacts the fixing cylinder, and opening the gripping means by a first opening amount immediately after the start of the movement so as to release the recording medium, then opening the gripping means by a second opening amount larger than the first opening amount when a pinched region is formed by sandwiching the recording medium between the heating member and the fixing cylinder, and then moving the peeling member so that the tip of the peeling member moves outside the outer periphery of the fixing cylinder, thereby peeling the recording medium off the fixing cylinder.

2. The gripping means has a fixed claw and a movable claw that comes into contact with and moves away from the fixed claw, the cam mechanism controls the contact and separation of the movable claw with respect to the fixed claw, thereby controlling the opening and closing of the gripping means; When the gripping means is opened to the second opening amount, the tip of the movable claw is out of the range of movement of the tip of the recording medium. The fixing device according to claim 1 .

3. an image forming unit that forms a developer image on a recording medium; a fixing device that fixes the developer image formed on the recording medium by the image forming unit onto the recording medium, The fixing device a rotating heating element; a cylindrical fixing drum that is disposed with its rotation axis oriented in the depth direction and that rotates, and that has a recessed portion formed on its outer circumferential surface that extends in the depth direction, and that applies pressure to the recording medium by clamping the recording medium in a clamping region formed between the fixing drum and the heating member; a gripping means for conveying the recording medium while gripping the leading edge thereof, and for passing the recording medium between the heating member and the fixing cylinder while being accommodated in the recessed portion as the fixing cylinder rotates; a peeling member that peels the recording medium that has passed through the pinch area from the fixing cylinder; a cam mechanism that is actuated by the rotation of the fixing cylinder, and that controls the contact and separation of the heating member with respect to the fixing cylinder, the movement of the peeling member, and the opening and closing of the gripping means, so that the recording medium is peeled off from the fixing cylinder by moving the heating member in a direction away from the fixing cylinder at the timing when the gripping means passes between the heating member and the fixing cylinder, then moving the peeling member in a direction where the tip of the peeling member enters into the recess from a position away from the outer periphery of the fixing cylinder, then starting the movement of the heating member in a direction where the heating member contacts the fixing cylinder, and opening the gripping means by a first opening amount immediately after the start of the movement, and then opening the gripping means by a second opening amount larger than the first opening amount when a pinched region is formed with the recording medium sandwiched between the heating member and the fixing cylinder, and then moving the peeling member so that the tip of the peeling member moves outside the outer periphery of the fixing cylinder, thereby peeling the recording medium off the fixing cylinder. Image forming device.

Images