JP2015175986A - Fixing device, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that has a simple configuration that moves a moving member between a contact position to be in contact with the inner peripheral surface of an endless member and a separation position to be separated from the inner peripheral surface of the endless member, and an image forming apparatus.SOLUTION: A fixing device 100 includes an urging mechanism 150 that urges a contact member 152 so as to move the contact member 152 to a contact position, and an opposing mechanism 180 that moves the contact member 152 from the contact position to a separation position. With this configuration, a simple configuration is provided, which moves the contact member 152 between the contact position and the separation position, compared with a configuration not using the opposing mechanism 180 and the urging mechanism 150.

Description

  The present invention relates to a fixing device and an image forming apparatus.

  The heating unit provided in the fixing device of Patent Document 1 includes an exciting coil, a fixing belt having a heat generating layer, a temperature-sensitive magnetic member in which the magnetic permeability starts to decrease continuously from the magnetic permeability change start temperature, and a temperature-sensitive magnetic material. And a contact / separation mechanism unit that contacts and separates the member from the fixing belt.

JP 2009-282413 A

  The subject of this invention is obtaining the simple structure which moves a moving member to the contact position which contacts the internal peripheral surface of an endless member, and the separated position which separates from the internal peripheral surface of an endless member.

  A fixing device according to claim 1 includes a magnetic field generating member that generates a magnetic field, an endless endless member that rotates partly on the outer peripheral surface of the magnetic field generating member, and generates heat by electromagnetic induction of the magnetic field, and rotates. A contact position that is disposed on the opposite side of the magnetic field generating member across the endless member, has an arc shape along the inner peripheral surface of the endless member, generates heat by electromagnetic induction of the magnetic field, and contacts the inner peripheral surface; A moving member that moves to a plurality of positions including a separation position that is separated from the inner peripheral surface, a biasing member that biases the moving member so that the moving member moves to the contact position, and the biasing By applying a counter force against the biasing force of the member to the moving member, the moving member is moved from the contact position to the separated position, and when the counter force is released, the moving member is moved to the contact position. A counter member that allows movement And wherein the Rukoto.

  A fixing device according to a second aspect is the fixing device according to the first aspect, wherein the biasing member is disposed on one end side of the moving member when viewed from the rotation axis direction of the endless member. And a second urging portion disposed on the other end side of the moving member.

  A fixing device according to a third aspect is the fixing device according to the first or second aspect, wherein the movement is performed on the opposite side to the magnetic field generating member with the moving member in between when viewed from the rotation axis direction of the endless member. Arranged so as to straddle a portion on one end side of the member and a portion on the other end side of the moving member, and supports a portion on one end side of the moving member and a portion on the other end side of the moving member; And a supporting member that suppresses the transmission of the magnetic field generated by the magnetic field generating member.

  The fixing device according to a fourth aspect is the fixing device according to any one of the first to third aspects, wherein the moving member includes the separation position, the contact position, a part of the moving member, and the inner circumference. The counter member moves a part of the counter force to the moving member so that the counter member moves the moving member from the contact position to the intermediate position. Further, the counter member imparts another part of the counter force to the moving member, whereby the counter member moves the moving member from the intermediate position to the separated position.

  5. The image forming apparatus according to claim 5, wherein the image forming unit forms an image on a recording medium, and the image is fixed to the recording medium on which the image is formed by the image forming unit. And a fixing device as described above.

  According to the fixing device of the first aspect, when the moving member is moved from the contact position to the separated position by applying a counter force against the urging force of the urging mechanism to the moving member, and the counter force is released, Compared to the case where a counter member that allows movement to the contact position is not provided, the moving member is moved to a contact position that contacts the inner peripheral surface of the endless member and a separated position that is separated from the inner peripheral surface of the endless member. A simple configuration can be obtained.

  According to the fixing device of the second aspect, the moving member can be moved in a state in which the posture of the moving member is stabilized as compared with the case where only the center of the moving member is urged toward the inner peripheral surface when viewed from the rotation axis direction. The moving member can be biased so that the member moves to the contact position.

  According to the fixing device of the third aspect, the magnetic field generated by the magnetic field generating member is disposed on the opposite side of the magnetic field generating member with the supporting member interposed therebetween, as compared with the case where the magnetic field is transmitted through the supporting member. The influence of the magnetic field on the remaining members can be suppressed.

  According to the fixing device of the fourth aspect, the temperature of the endless member is increased by 1 ° C. as compared with the case where the moving member does not move to an intermediate position where a part of the moving member and the inner peripheral surface are in contact with each other. The set value of the amount of heat can be increased.

  According to the image forming apparatus of the fifth aspect, the image forming apparatus is downsized as compared with the case where the fixing apparatus according to any one of the first to fourth aspects is not provided.

1 is a cross-sectional view illustrating a fixing belt and the like used in a fixing device according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing belt and the like used in a fixing device according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a countermeasure mechanism and the like used in the fixing device according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view showing a fixing belt, an excitation coil, and the like used in the fixing device according to the first embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device according to a first embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device according to a first embodiment of the present invention. 2A and 2B are a cross-sectional view of a temperature-sensitive magnetic plate used in the fixing device according to the first embodiment of the present invention, and a schematic diagram showing the relationship between the magnetic permeability and temperature of the temperature-sensitive magnetic member. 1 is a cross-sectional view of a fixing belt used in a fixing device according to a first embodiment of the present invention. 1 is a configuration diagram illustrating an image forming unit used in an image forming apparatus according to a first embodiment of the present invention. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment of the present invention. FIG. 6 is a cross-sectional view showing a fixing belt used in a fixing device according to a second embodiment of the present invention. FIG. 6 is a cross-sectional view showing a fixing belt used in a fixing device according to a second embodiment of the present invention.

<First Embodiment>
An example of a fixing device according to a first embodiment of the present invention and an image forming apparatus including the fixing device will be described with reference to FIGS. The arrow V shown in the figure is the vertical direction and indicates the vertical direction of the apparatus, the arrow H is the horizontal direction and indicates the apparatus width (left and right of the apparatus), and the arrow D is the horizontal direction and indicates the apparatus depth direction. Show.

(overall structure)
In the image forming apparatus 10 according to the present embodiment, as shown in FIG. 11, image formation is performed with toner (developer) of four colors of yellow (Y), magenta (M), cyan (C), and black (K). The image forming units 12Y, 12M, 12C, and 12K as an example of the image forming unit that performs the image forming operation are arranged in a diagonally lower left direction with respect to the apparatus width direction on the center side in the housing 11 of the image forming apparatus 10. . The arrangement order of the image forming units 12 is Y, M, C, K from the upper right to the lower left.

  The image forming units 12Y to 12K have the same configuration except for the toners of the respective colors that are accommodated. Therefore, in the following description, when distinguishing each color of yellow, magenta, cyan, and black, it will be described with a symbol with Y, M, C, and K letters added after the number, but there is no need to distinguish each color. The letters Y, M, C, and K after the numbers are omitted.

  Above each of the image forming units 12Y to 12K, a transfer unit 14 is provided for transferring the toner images (images) formed by the image forming units 12Y to 12K onto a sheet member P as an example of a recording medium. The transfer unit 14 is an endless intermediate transfer belt 16 and four primary transfer rolls arranged inside the intermediate transfer belt 16 for transferring the toner images of the image forming units 12Y to 12K to the intermediate transfer belt 16. 18Y, 18M, 18C, and 18K, and a secondary transfer roll 20 for transferring the toner image superimposed on the intermediate transfer belt 16 to the sheet member P.

  The intermediate transfer belt 16 is disposed facing the secondary transfer roll 20, and is wound around a drive roll 26 driven by a motor (not shown) and a support roll 22 that is rotatably supported. However, by being driven and rotated by a motor (not shown), the intermediate transfer belt 16 is circulated and moved in the direction of arrow A (clockwise direction in the figure).

  Each of the primary transfer rolls 18Y to 18K is disposed so as to face an image carrier 28 described later of each of the image forming units 12Y to 12K with the intermediate transfer belt 16 interposed therebetween. A transfer voltage having a polarity opposite to the toner polarity (positive polarity as an example in the present embodiment) is applied to each of the primary transfer rolls 18Y to 18K.

  Further, a transfer voltage having a polarity opposite to the toner polarity is applied to the secondary transfer roll 20. A cleaning device (not shown) is provided on the outer peripheral surface of the intermediate transfer belt 16 where the support roll 22 is provided, and residual toner, paper dust, and the like on the intermediate transfer belt 16 are removed by this cleaning device. It is supposed to be removed.

  On the other hand, below the image forming unit 12, a paper feeding unit 46 in which the sheet member P is stored is provided. In addition, a sheet conveyance path 50 through which the sheet member P is conveyed is provided vertically upward from the left end of the sheet feeding unit 46.

  In the sheet conveyance path 50, a delivery roll 48 that sends out the sheet member P from the sheet feeding unit 46, a conveyance roll 52 that is composed of a pair of rolls that convey the sheet member P, and an image transfer timing on the intermediate transfer belt 16. And a positioning roll 54 configured by a pair of rolls that match the conveyance timing of the sheet member P is provided.

  Then, the sheet member P sequentially sent from the paper supply unit 46 by the sending roll 48 is conveyed to the secondary transfer position of the intermediate transfer belt 16 by the alignment roll 54 via the paper conveyance path 50. Yes.

  A fixing device 100 is provided on the downstream side (upper side) of the secondary transfer roll 20 on the paper conveyance path 50. The fixing device 100 includes a fixing belt 102 and a pressure roll 104 (an example of a pressing member), and heats and presses the sheet member P to fix the toner image transferred to the sheet member P to the sheet member P. It is like that. Details of the fixing device 100 will be described later.

  In addition, on the downstream side of the fixing device 100 on the paper conveyance path 50, a discharge roll 66 composed of a pair of rolls for discharging the fixed sheet member P to the outside of the housing 11 is provided. The sheet member P discharged at 66 is discharged to a discharge portion 67 formed on the upper surface of the housing 11. In the housing 11, a control unit 36 that performs drive control of each unit of the image forming apparatus 10 is provided above the transfer unit 14.

  Next, the image forming unit 12 will be described.

  As shown in FIG. 10, the image forming unit 12 includes an image carrier 28 that is rotationally driven in the direction of arrow B (counterclockwise direction in the drawing), and an image carrier that is in contact with the outer peripheral surface of the image carrier 28. A charging roll 72 that charges the outer periphery 28, an exposure unit 70 as an example of an exposure unit that irradiates the outer peripheral surface of the image carrier 28 with exposure light to form an electrostatic latent image, and a static on the outer peripheral surface of the image carrier 28 A developing roll 78 that develops the electrostatic latent image with toner, a neutralizing lamp 74 that performs neutralization by irradiating the outer peripheral surface of the image holding body 28 after transfer, and an outer peripheral surface of the image holding body 28 after static elimination are cleaned. And a cleaning blade 76.

  Further, the charging roll 72, the exposure unit 70, the developing roll 78, the charge eliminating lamp 74, and the cleaning blade 76 face the outer peripheral surface of the image holding body 28, respectively, from the upstream side to the downstream side in the rotation direction of the image holding body 28. Are arranged in this order.

  Further, on the opposite side of the image carrier 28 with respect to the charging roll 72, a cleaning roll 68 for removing an external additive of toner attached to the outer peripheral surface of the charging roll 72 is rotatably provided. The charging roll 72 is connected to energizing means (not shown), and energized during image formation while being driven to rotate, and charges the outer peripheral surface of the image carrier 28.

  Below the developing roll 78, a spiral (for example, a mixture of resin toner and metal carrier) supplied from a toner supply unit (not shown) is stirred (mixed) and supplied to the developing roll 78. Two conveying members 38 are provided. A thin layer forming roll 24 is provided opposite to the outer peripheral surface of the developing roll 78.

  The thin layer forming roll 24 is disposed upstream of the image carrier 28 in the rotational direction of the developing roll 78 and spaced from the outer peripheral surface of the developing roll 78, and the developer on the outer peripheral surface of the developing roll 78. The developer layer (thin layer) having a predetermined thickness is formed on the developing roll 78 by restricting the amount of toner passing therethrough.

  The developing roller 78 includes a fixed magnet roller (not shown) and a cylindrical developing sleeve (not shown) that is rotatably provided outside the magnet roller. A voltage is applied between the developing roller 78 and the image carrier 28 to form an electric field during development, and the developing roller 78 rotates the toner in the developer to the electrostatic latent image of the image carrier 28 while rotating. It is designed to move toward the statue.

  In addition, the image forming unit 12 has a main body portion that includes a lower housing 13 and an upper housing 15. The lower housing 13 is provided with a developing roll 78, a conveying member 38, and a thin layer forming roll 24. The upper housing 15 has an image carrier 28, an exposure unit 70, a charging roll 72, a cleaning roll 68, and a cleaning blade. 76, a static elimination lamp 74 is provided.

(Operation of the overall configuration)
Next, an image forming process of the image forming apparatus 10 will be described.

  As shown in FIG. 11, when each unit of the image forming apparatus 10 is activated, the image data subjected to image processing by the control unit 36 is converted into color material gradation data of each color, and is supplied to the exposure unit 70. Output sequentially.

  The exposure unit 70 emits each exposure light according to the color material gradation data of each color, and the outer peripheral surface of each image carrier 28 charged by the charging roll 72 is exposed. Thereby, an electrostatic latent image is formed on the outer peripheral surface of each image carrier 28.

  The electrostatic latent images formed on the outer peripheral surfaces of the image carriers 28 are respectively developed with toner images (developers) of yellow (Y), magenta (M), cyan (C), and black (K) by the developing roll 78. Developed as an image). The toner images of the respective colors sequentially formed on the image holders 28 of the image forming units 12Y to 12K are sequentially multiplex-transferred onto the intermediate transfer belt 16 by the four primary transfer rolls 18Y to 18K.

  The toner images of the respective colors transferred onto the intermediate transfer belt 16 are secondarily transferred by the secondary transfer roll 20 onto the sheet member P conveyed from the paper supply unit 46. Then, the toner images of the respective colors on the sheet member P are fixed by the fixing device 100, and the fixed sheet member P is discharged to the discharge unit 67 by the discharge roll 66.

  Residual toner, paper dust, and the like are removed from the outer peripheral surface of the image carrier 28 after the primary transfer of the toner image by the cleaning blade 76.

(Configuration of fixing device)
Next, the fixing device 100 will be described.

  As shown in FIG. 7, the fixing device 100 includes a casing 120 in which openings 120 </ b> A and 120 </ b> B for entering or discharging the sheet member P are formed. An endless fixing belt 102 (an example of an endless member) is provided inside the housing 120. A cylindrical cap member (not shown) having a rotating shaft is fitted and fixed to both ends of the fixing belt 102, and the fixing belt 102 is supported rotatably about the rotating shaft. . One cap member is formed with a gear for transmitting a rotational force of a motor (not shown) that rotates the fixing belt 102. The fixing belt 102 rotates in the direction of arrow E by operating the motor.

  A bobbin 108 made of an insulating member is disposed at a position facing a part of the outer peripheral surface of the fixing belt 102.

[Bobbin]
As shown in FIG. 7, the bobbin 108 has an arc shape that follows the outer peripheral surface of the fixing belt 102 when viewed from the rotation axis direction of the fixing belt 102 (in this embodiment, the same direction as the apparatus depth direction). Yes. Further, in the bobbin 108, a convex portion 108 </ b> A is formed on the center side in the circumferential direction of the surface opposite to the fixing belt 102. The interval between the bobbin 108 and the fixing belt 102 is about 1 to 3 mm.

  An exciting coil 110 (an example of a magnetic field generating member) that generates a magnetic field H by energization is wound around the bobbin 108 a plurality of times around the convex portion 108A. A magnetic core 112 formed in an arc shape following the arc shape of the bobbin 108 is disposed at a position facing the excitation coil 110, and the magnetic core 112 is supported by the bobbin 108 or the excitation coil 110.

[Fixing belt]
As shown in FIG. 9, the fixing belt 102 includes a base layer 124, a heat generation layer 126, an elastic layer 128, and a release layer 130 arranged from the inside to the outside, and these are laminated. It is united. For example, the fixing belt 102 has a diameter of 30 mm and a width direction length of 370 mm.

  The base layer 124 has a strength to support the heat generating layer 126, has heat resistance, and is made of a member that penetrates the magnetic flux of the magnetic field H and hardly generates heat due to the action of the magnetic field. In this embodiment, a nonmagnetic stainless steel having a thickness of 35 μm is used as the base layer 124.

  The heat generating layer 126 is composed of a member that generates heat by electromagnetic induction. Further, the heat generating layer 126 is made thinner than the skin depth, which is the thickness at which the magnetic field H can penetrate, in order to penetrate the magnetic flux of the magnetic field H. In the present embodiment, copper having a thickness of 10 μm is used as the heat generating layer 126.

  The elastic layer 128 is composed of a member having elasticity and heat resistance. In the present embodiment, 200 μm thick silicon rubber is used as the elastic layer 128.

  The release layer 130 is composed of a member that facilitates peeling of the sheet member P from the fixing belt 102. In this embodiment, a 30 μm thick tetrafluoroethylene / perfluoroalkoxyethylene copolymer resin is used as the release layer 130.

  Furthermore, as shown in FIG. 7, the fixing belt 102 is located inside the fixing belt 102 in a region that does not face the exciting coil 110 in the radial direction and in the discharge side region (upper region in the drawing) of the sheet member P. A temperature detection sensor 134 for detecting the temperature 102 is disposed.

  Further, on the inner side of the fixing belt 102, an arc shape along the inner peripheral surface of the fixing belt 102 is formed on the opposite side of the radial direction across the fixing belt 102 with respect to the bobbin 108. Contact member 152 (an example of a moving member) is provided.

(Contact member)
The contact member 152 includes a temperature-sensitive magnetic plate 114 that is a temperature-sensitive magnetic member arranged in layers, and a substrate 154 that is arranged in layers inside the temperature-sensitive magnetic plate 114.

  The temperature-sensitive magnetic plate 114 has temperature-sensitive characteristics as shown in FIG.

  It is composed of a member having a temperature-sensing characteristic in which the magnetic permeability starts to continuously decrease from the magnetic permeability change start temperature in the temperature range that is equal to or higher than the fixing (heating) setting temperature of the fixing belt 102 and lower than the heat resistance temperature of the fixing belt 102. ing. In this embodiment, a 300 μm thick iron-nickel alloy (Fe—Ni) is used as the temperature-sensitive magnetic plate 114.

  The magnetic permeability change start temperature is a temperature at which the magnetic permeability (measured according to JIS C2531) starts to decrease, and refers to a point at which the magnetic flux penetration amount starts to change (see FIG. 8B).

  The substrate 154 is configured by a member that retains heat generated by the temperature-sensitive magnetic plate 114 and conducts the retained heat in the depth direction of the apparatus. As a result, the temperature distribution in the apparatus depth direction of the temperature-sensitive magnetic plate 114 becomes the same, and local (partial) temperature rise is suppressed. Further, when the temperature of the temperature-sensitive magnetic plate 114 rises and the magnetic permeability decreases above the magnetic permeability change start temperature, the magnetic flux penetrating the fixing belt 102 is reduced so that the heat generation amount of the fixing belt 102 is suppressed. It has become. In the present embodiment, aluminum having a thickness of 400 μm is used as the substrate 154.

  Further, as shown in FIG. 7, there is a feeling in the area inside the fixing belt 102 that is not opposed to the exciting coil 110 in the radial direction and in the area on the entry side of the sheet member P (lower area in the figure). A temperature detection sensor 135 for detecting the temperature of the thermal magnetic plate 114 is disposed.

  On the other hand, a support member 118 is provided inside the contact member 152 (left side in the figure).

(Support member)
The support member 118 extends in the apparatus depth direction, is formed by bending an aluminum plate, has a thickness equal to or greater than the above-described skin depth, and is configured of a member that does not allow the magnetic flux of the magnetic field H to penetrate.

  The support member 118 is disposed so as to straddle the upper end of the contact member 152 (an example of a portion on one end side) and the lower end of the contact member 152 (an example of a portion on the other end side). The upper end of the support member 118 supports the upper end of the contact member 152, and the lower end of the support member 118 supports the lower end of the contact member 152.

  A through hole 118 </ b> A through which a rod 184 described later passes is formed at a portion between the upper end and the lower end of the support member 118.

  Furthermore, a frame 158 that supports the support member 118 is provided so that the support member 118 moves in the apparatus width direction.

〔flame〕
As shown in FIG. 4, the frame 158 is disposed on the opposite side of the contact member 152 with the support member 118 interposed therebetween. The frame 158 includes a main body member 160 extending in the apparatus depth direction, an upper support member 162 that supports an upper portion of the support member 118, a lower support member 164 that supports a lower portion of the support member 118, It has.

  The main body member 160 is disposed so as to extend in the apparatus depth direction. The main body member 160 has a pentagonal outer shape when viewed from the apparatus depth direction, and a space 160 </ b> A is formed inside the main body member 160. Both ends of the main body member 160 in the apparatus depth direction are fixed to the housing 120.

  Further, an upper support member 162 is attached to the upper surface 160B of the main body member 160, and a lower support member 164 is attached to the lower surface 160C of the main body member 160.

  As shown in FIG. 1, the upper support member 162 is formed in an inverted L shape by bending a cylindrical bar, and a plurality of the upper support members 162 are arranged at intervals in the apparatus depth direction. In the upper support member 162, an extended part 162 </ b> B extending in the apparatus width direction toward the support member 118 is formed with a diameter-enlarged part 162 </ b> A whose diameter is increased. Furthermore, the distal end side of the extended portion 162 </ b> B passes through a through hole (not shown) formed in the support member 118. Thereby, the upper part of the support member 118 is guided by the extended portion 162B and moves in the apparatus width direction.

  Further, between the enlarged diameter portion 162 </ b> A and the support member 118, the upper part of the contact member 152 (one example of one end side) is biased toward the inner peripheral surface of the fixing belt 102 via the support member 118. A coil spring 166 (an example of a first urging portion) is disposed.

  The lower support member 164 is formed in an L shape by bending a columnar bar, and a plurality of lower support members 164 are arranged at intervals in the apparatus depth direction. In the lower support member 164, an extended portion 164 </ b> B extending in the apparatus width direction toward the support member 118 is formed with an enlarged diameter portion 164 </ b> A having an enlarged diameter. Furthermore, the distal end side of the extending portion 164B passes through a through hole (not shown) formed in the support member 118. Thereby, the lower part of the support member 118 is guided by the extended portion 164B and moves in the apparatus width direction.

  Further, a lower part of the contact member 152 (an example of a part on the other end side) is attached between the enlarged diameter portion 164A and the support member 118 via the support member 118 toward the inner peripheral surface of the fixing belt 102. A coil spring 170 (an example of a second urging portion) that urges is disposed.

  As described above, the urging mechanism 150 as an example of the urging member that urges the contact member 152 toward the inner peripheral surface of the fixing belt 102 includes the coil spring 166 and the coil spring 170. The urging force (spring force) of the coil spring 170 and the coil spring 166 will be described together with a counter mechanism 180 described later.

  On the other hand, in a space 160A formed inside the main body member 160, a support member 118 is pulled toward the main body member 160, and a counter mechanism 180 (an example of a counter member) that separates the contact member 152 from the inner peripheral surface of the fixing belt 102. ) Is provided.

[Countermeasure mechanism]
As shown in FIG. 3, the counter mechanism 180 includes an eccentric cam 182 whose axial direction is the depth direction of the device, and a rod 184 whose proximal end is in contact with the circumferential surface of the eccentric cam 182 and whose distal end passes through the through hole 118A. I have. The eccentric cam 182 and the rod 184 are disposed on both sides of the support member 118 in the apparatus depth direction.

  Both ends of the shaft portion 182A of the eccentric cam 182 are rotatably supported by a housing 120 via a bearing (not shown), and rotational force is applied to the shaft portion 182A from a driving member (not shown) (for example, a stepping motor). It is to be transmitted.

  The rod 184 passes through the through hole 160D formed in the main body member 160 and the through hole 118A. The rod 184 is inclined with respect to the apparatus width direction so that the tip of the rod 184 is positioned below the base end. Further, the base end of the rod 184 is formed with a diameter-expanded portion 184A having an enlarged diameter, and the tip of the rod 184 is formed with an enlarged-diameter portion 184B having an enlarged diameter.

  In addition, a coil spring 186 is disposed between the enlarged diameter portion 184A and the periphery of the through hole 160D. The coil spring 186 urges the rod 184 toward the eccentric cam 182 so as to press the enlarged diameter portion 184A against the outer peripheral surface of the eccentric cam 182.

  On the other hand, the tip of the rod 184 passes through the through hole 118A of the support member 118, and the aforementioned enlarged diameter portion 184B is formed at the tip of the penetrating rod 184.

  As shown in FIG. 5, the contact member 152 so that the distance between the contact member 152 moved to the separated position and the inner peripheral surface of the fixing belt 102 falls within a predetermined range when viewed from the depth direction of the apparatus. Stoppers 140 and 142 are provided for restricting the positions of the two.

  Six stoppers 140 and 142 are arranged at intervals in the apparatus depth direction. The stopper 140 contacts the upper part of the support member 118 so as to regulate the position of the contact member 152 moved to the separated position, and the stopper 142 regulates the position of the contact member 152 moved to the separated position. The lower portion of the support member 118 is in contact with the lower portion.

  Next, the biasing force (spring force) of the coil spring 166, the coil spring 170, and the coil spring 186 will be described.

  In the following description, the force that biases the upper side of the contact member 152 toward the inner peripheral surface of the fixing belt 102 by all the coil springs 166 is referred to as “upper biasing force”. In contrast, a force that urges the lower side of the contact member 152 toward the inner peripheral surface of the fixing belt 102 by all the coil springs 170 is referred to as a “lower urging force”. Further, the force that urges the rod 184 toward the eccentric cam 182 by all the coil springs 186 is referred to as “counter biasing force”. Furthermore, as shown in FIG. 5, a region G where the pulling force by the rod 184 acts on the support member 118 is defined.

  The counter biasing force is strengthened against the biasing force obtained by adding up the upper biasing force and the lower biasing force in all states.

  In addition, each parameter is determined so that the rotational moment generated in the part G by the upper biasing force is larger than the rotational moment generated in the part G by the lower biasing force in a state where the contact member 152 is moved to the separated position. Yes. In the present embodiment, examples of the parameters include the spring constants and compression amounts of the coil springs 166 and 170, and distances (T1 and T2 in the drawing) from the portion G to the coil springs 166 and 170 in the vertical direction of the apparatus.

  With this configuration, by rotating the eccentric cam 182, the rod 184 moves in the longitudinal direction of the rod 184, and a counterforce that opposes the upper biasing force and the lower biasing force is applied to the support member 118, and the coil spring 166 and the coil spring Shrink 170. Thereby, the support member 118 and the contact member 152 are moved in the apparatus width direction. Then, when the eccentric cam 182 is rotated and the support member 118 is pulled into the main body member 160 most, the entire contact member 152 is separated from the inner peripheral surface of the fixing belt 102 as shown in FIG. Is moved to the separated position.

  Further, the eccentric cam 182 is rotated 90 degrees from the state where the contact member 152 has moved to the separated position. Then, the movement of the support member 118 and the contact member 152 is partially allowed, the support member 118 is tilted, and as shown in FIG. 2, the upper part of the contact member 152 (about the upper half: range K in the figure) The contact member 152 contacts the inner peripheral surface of the fixing belt 102 and moves to an intermediate position.

  Further, the eccentric cam 182 rotates 90 degrees from the state in which the contact member 152 has moved to the intermediate position by the rotational force of the drive member (not shown). As a result, the movement of the support member 118 and the contact member 152 is all permitted, and the lower portion of the contact member 152 moves in the apparatus width direction. As shown in FIG. The contact member 152 moves to the contact position in contact with the inner peripheral surface.

  The contact member 152 is moved from the contact position to the intermediate position and further moved from the intermediate position to the separated position by performing the operation opposite to the above-described operation.

  Then, the control unit 36 moves the contact member 152 in accordance with an instruction from the user or the like, so that the fixing device 100 can be switched between a quick startup mode, a high productivity mode, and an intermediate mode. .

  The rapid start-up mode is a mode in which priority is given to shortening the temperature increase time of the fixing belt 102 (hereinafter referred to as “belt temperature increase time”) after the job is instructed by the user. In the quick start-up mode, the contact member 152 has moved to the separated position.

  In the high productivity mode, a time period (hereinafter referred to as “job execution time”) from when a job instructed by raising the temperature of the fixing belt 102 (a job for forming an image on a plurality of sheet members P) to the end thereof is executed (hereinafter referred to as a job) This mode gives priority to shortening the “job execution time”). In the high productivity mode, the contact member 152 has moved to the contact position.

  The belt temperature rise time in the high productivity mode is longer than the belt temperature rise time in the rapid startup mode, but the job execution time in the high productivity mode is the same as that in the rapid startup mode. Shorter than the job execution time.

  The intermediate mode is a mode that is allowed by the user for both the belt temperature rising time and the job execution time. In the intermediate mode, the contact member 152 has moved to the intermediate position.

  The belt temperature increase time in the intermediate mode is longer than the belt temperature increase time in the rapid start-up mode, and is shorter than the belt temperature increase time in the high productivity mode. Furthermore, the job execution time in the intermediate mode is shorter than the job execution time in the rapid startup mode and longer than the job execution time in the high productivity mode.

  The details of the quick start-up mode, the high productivity mode, and the intermediate mode will be described together with the operation described later.

  On the other hand, as shown in FIG. 7, a pressing pad 132 sandwiching the fixing belt 102 with the pressure roll 104 is fixed on the opposite side to the side on which the support member 118 is disposed in the main body member 160. Yes. In the present embodiment, a liquid crystal polymer is used as a material constituting the pressing pad 132.

[Pressure roll]
As shown in FIG. 7, the pressure roll 104 includes a cored bar 104A made of a metal such as aluminum, and a sponge elastic layer 104B of foamed silicon rubber having a thickness of 5 mm that is covered with the cored bar 104A. Yes. Furthermore, the pressure roll 104 includes a release layer (not shown) made of carbon tetrafluoride ethylene / perfluoroalkoxyethylene copolymer resin (PFA) containing carbon having a thickness of 50 μm outside the sponge elastic layer 104B. ing.

  Further, the core metal 104A of the pressure roll 104 is moved by a retract mechanism (not shown) so as to move in the apparatus width direction. By this retract mechanism, the pressure roll 104 is in contact with the fixing belt 102 and presses the fixing belt 102 (see FIGS. 6 and 7), and a non-pressure position that separates from the fixing belt 102 (see FIG. 6). 5)).

  Further, a rotational force from a motor (not shown) is transmitted to the cored bar 104A of the pressure roll 104 so that the pressure roll 104 rotates in the direction of arrow F shown in FIG. 7 (the direction opposite to the direction of arrow E). It has become.

(Operation of fixing device)
Next, a case where the fixing device 100 operates in the quick start-up mode, a case where the fixing device 100 operates in the high productivity mode, and a case where the fixing device 100 operates in the intermediate mode according to an instruction from the user or the like will be described. To do.

(Rapid startup mode)
In the non-operating state of the fixing device 100, as shown in FIG. 5, the pressure roll 104 has moved to a non-pressure position that is separated from the fixing belt 102, and the contact member 152 has an inner periphery of the fixing belt 102. It has moved to a separated position that is separated from the surface.

  When a job is instructed by the user and the image forming apparatus 10 is operated, the sheet member P to which the toner image is transferred is conveyed toward the fixing device 100. In the fixing device 100, the movement of the contact member 152 to the separated position is maintained under the control of the control unit 36. The fixing belt 102 rotates in the direction of arrow E in response to a rotational force from a motor (not shown).

  Further, an alternating current is supplied to the exciting coil 110, and the magnetic field H as a magnetic circuit is repeatedly generated and disappeared around the exciting coil 110. When the magnetic field H crosses the heat generating layer 126 (see FIG. 9) of the fixing belt 102, an eddy current is generated in the heat generating layer 126 so that a magnetic field that prevents the magnetic field H from changing is generated. As a result, the fixing belt 102 generates heat. Here, since the contact member 152 has moved to the separated position, the amount of heat for raising the temperature of the fixing belt 102 by 1 ° C. (hereinafter referred to as “belt heat amount”) as compared with the case where the contact member 152 has moved to the contact position. ") Is small. As a result, the belt temperature rising time is shorter than when the contact member 152 has moved to the contact position.

  After the fixing belt 102 reaches the fixing set temperature, the pressure roll 104 receives a rotational force from a motor (not shown) and rotates in the arrow F direction. Further, the retract mechanism is operated, and the pressure roll 104 is moved from the non-pressure position to the pressure position as shown in FIG. When the pressure roll 104 moves to the pressure position, the rotational force transmitted to the fixing belt 102 is released, and the fixing belt 102 rotates following the rotation of the pressure roll 104.

  Then, the sheet member P conveyed toward the fixing device 100 is pressed by the fixing belt 102 having a fixing set temperature (170 ° C.) and the pressure roll 104, and the toner image is applied to the surface of the sheet member P. To settle. Then, the sheet member P on which the toner image is fixed is discharged to the discharge portion 67 by the discharge roll 66 (see FIG. 11).

  The temperature of the fixing belt 102 decreases as it contacts the sheet member P. The temperature of the fixing belt 102 whose temperature has decreased is detected by the temperature detection sensor 134. When the temperature of the fixing belt 102 is lower than the fixing setting temperature, an alternating current is supplied to the exciting coil 110 again, and the fixing belt 102 is restored. Temperature rises. In this way, by repeating the supply and stop of the alternating current to the exciting coil 110, the magnetic field H is intermittently generated by the exciting coil 110, and the temperature of the fixing belt 102 is maintained at the fixing set temperature.

  Here, as described above, since the contact member 152 has moved to the separated position, the amount of heat of the belt is small. As a result, the amount of change in the temperature of the fixing belt 102 that decreases as the fixing belt 102 contacts the sheet member P is larger than the amount of change in the temperature of the fixing belt 102 when the contact member 152 moves to the contact position. Big. For this reason, it is necessary to raise the temperature of the fixing belt 102 again.

  Then, the control unit 36 adjusts the conveyance speed (or conveyance interval) of the sheet member P in consideration of the time during which the fixing belt 102 is heated.

[High productivity mode]
As for the high productivity mode, the difference from the rapid start-up mode will be mainly described.

  When a job is instructed by the user and the image forming apparatus 10 is operated, the sheet member P to which the toner image is transferred is conveyed toward the fixing device 100. In the fixing device 100, the eccentric cam 182 rotates 180 degrees under the control of the control unit 36, and the entire contact member 152 comes into contact with the inner peripheral surface of the fixing belt 102 as shown in FIG. 152 moves from the separated position to the contact position. The fixing belt 102 rotates in the direction of arrow E in response to a rotational force from a motor (not shown).

  The fixing belt 102 generates heat due to the magnetic field H generated by the exciting coil 110 (see FIG. 4). Here, since the contact member 152 has moved to the contact position, the amount of heat of the belt becomes larger than when the contact member 152 has moved to the separated position. As a result, the belt temperature rising time becomes longer than when the contact member 152 has moved to the separated position.

    After the fixing belt 102 reaches the fixing set temperature, the pressure roll 104 is moved from the non-pressure position to the pressure position by the retract mechanism. Then, the sheet member P conveyed toward the fixing device 100 is pressed by the fixing belt 102 at the fixing set temperature and the pressure roll 104, and the toner image is fixed on the surface of the sheet member P.

  The temperature of the fixing belt 102 decreases as it contacts the sheet member P. The temperature of the fixing belt 102 whose temperature has decreased is detected by the temperature detection sensor 134. When the temperature of the fixing belt 102 is lower than the fixing setting temperature, an alternating current is supplied to the exciting coil 110 again, and the fixing belt 102 is restored. Temperature rises. In this way, by repeating the supply and stop of the alternating current to the exciting coil 110, the magnetic field H is intermittently generated by the exciting coil 110, and the temperature of the fixing belt 102 is maintained at the fixing set temperature.

  Here, as described above, since the contact member 152 has moved to the contact position, the heat capacity including the belt is large. The contact member 152 also generates heat due to the magnetic field H.

  The amount of change in temperature that is decreased when the fixing belt 102 is in contact with the sheet member P is smaller than when the contact member 152 is moved to the separated position. Thereby, the frequency of raising the temperature of the fixing belt 102 again is lower than when the contact member 152 is moved to the separated position.

  Then, the control unit 36 adjusts the conveyance speed (or conveyance interval) of the sheet member P in consideration of the time during which the fixing belt 102 is heated. Since the frequency of raising the temperature of the fixing belt 102 again is lower than when the contact member 152 is moved to the separated position, the conveyance speed of the sheet member P is moved to the separated position. It becomes faster than the case. As a result, the job execution time is shorter than when the contact member 152 is moved to the separated position (rapid startup mode).

[Intermediate mode]
Regarding the intermediate mode, the difference from the rapid start-up mode will be mainly described.

  When a job is instructed by the user and the image forming apparatus 10 is operated, the sheet member P to which the toner image is transferred is conveyed toward the fixing device 100. In the fixing device 100, the eccentric cam 182 rotates 90 degrees under the control of the control unit 36, and the upper part of the contact member 152 is in contact with the inner peripheral surface of the fixing belt 102 as shown in FIG. The member 152 moves to the intermediate position. The fixing belt 102 rotates in the direction of arrow E in response to a rotational force from a motor (not shown).

  The fixing belt 102 generates heat due to the magnetic field H generated by the exciting coil 110 (see FIG. 4). Here, since the contact member 152 is moved to the intermediate position, the amount of heat of the belt is increased and the contact member 152 is moved to the contact position as compared with the case where the contact member 152 is moved to the separated position. Compared to the case, the amount of heat of the belt becomes smaller. As a result, the belt temperature raising time is longer than when the contact member 152 is moved to the separated position, and shorter than when the contact member 152 is moved to the contact position.

  After the fixing belt 102 reaches the fixing set temperature, the pressure roll 104 is moved from the non-pressure position to the pressure position by the retract mechanism. Then, the sheet member P conveyed toward the fixing device 100 is pressed by the fixing belt 102 at the fixing set temperature and the pressure roll 104, and the toner image is fixed on the surface of the sheet member P.

  The temperature of the fixing belt 102 decreases as it contacts the sheet member P. The temperature of the fixing belt 102 whose temperature has decreased is detected by the temperature detection sensor 134. When the temperature of the fixing belt 102 is lower than the fixing setting temperature, an alternating current is supplied to the exciting coil 110 again, and the fixing belt 102 is restored. Temperature rises. In this way, by repeating the supply and stop of the alternating current to the exciting coil 110, the magnetic field H is intermittently generated by the exciting coil 110, and the temperature of the fixing belt 102 is maintained at the fixing set temperature.

  Here, as described above, since the contact member 152 has moved to the intermediate position, the heat capacity including the belt is larger than that in the case where the contact member 152 has moved to the separated position, and the contact member 152 has The amount of heat of the belt is smaller than when moving to the contact position. The contact member 152 also generates heat due to the magnetic field H.

  The frequency of raising the temperature of the fixing belt 102 again is lower than that when the contact member 152 is moved to the separated position, and is higher than when the contact member 152 is moved to the contact position. .

  For this reason, the conveyance speed of the sheet member P is faster than when the contact member 152 is moved to the separation position, and is slower than when the contact member 152 is moved to the contact position. As a result, the job execution time is shorter than when the contact member 152 is moved to the separation position, and longer than when the contact member 152 is moved to the contact position.

(Summary)
As described above, the fixing device 100 includes the biasing mechanism 150 that biases the contact member 152 so that the contact member 152 moves to the contact position, and the counter mechanism 180 that moves the contact member 152 from the contact position to the separated position. And. As a result, a simple configuration in which the contact member 152 is moved between the contact position and the separation position can be obtained as compared with the configuration in which the counter mechanism 180 and the urging mechanism 150 are not used.

  Further, since the urging mechanism 150 and the counter mechanism 180 are disposed inside the fixing belt 102, the depth of the apparatus is smaller than when the urging mechanism or the counter mechanism is disposed outside the fixing belt 102. The space occupied by the fixing device 100 in the direction is reduced.

  The biasing mechanism 150 includes a coil spring 166 that biases the upper part of the contact member 152 toward the inner peripheral surface of the fixing belt 102, and the lower part of the contact member 152 on the inner peripheral surface of the fixing belt 102. And a coil spring 170 that biases it toward the surface. Therefore, as compared with the case where only the center of the contact member 152 is urged toward the inner peripheral surface of the fixing belt 102, the contact member 152 has the inner surface of the fixing belt 102 in a state in which the posture of the contact member 152 is stabilized. It is urged toward the circumferential surface.

  The support member 118 extends in the depth direction of the apparatus and has a thickness that prevents the magnetic field H generated by the excitation coil 110 from penetrating. For this reason, the magnetic field H is suppressed from reaching the eccentric cam 182 and the like, and the influence of the magnetic field H on the eccentric cam 182 and the like is suppressed.

  In addition, by moving the contact member 152 to the separated position, a rapid start-up mode in which the belt temperature rise time is prioritized, and by moving the contact member 152 to the contact position, job execution time is prioritized. It becomes a mode. Further, by moving the contact member 152 to the intermediate position, the intermediate mode allowed by the user is obtained for both the belt temperature raising time and the job execution time.

  Further, in the image forming apparatus 10, the image forming apparatus 10 is reduced in size by reducing the exclusive space of the fixing device 100 in the apparatus depth direction.

Second Embodiment
Next, an example of a fixing device and an image forming apparatus according to the second embodiment of the present invention will be described with reference to FIGS. In addition, about the same member as 1st Embodiment, the same code | symbol is attached | subjected, the description is abbreviate | omitted, and a different part from 1st Embodiment is mainly demonstrated.

  As shown in FIG. 12, the upper support member 202 is attached to the upper surface 160B of the main body member 160 of the fixing device 200 of the second embodiment, and the lower support member 204 is attached to the lower surface 160C of the main body member 160. Yes.

  The upper support member 202 is formed in an inverted L shape by bending a cylindrical bar, and a plurality of the upper support members 202 are arranged at intervals in the apparatus depth direction. In the upper support member 202, the distal end side of the extending portion 202 </ b> B extending in the apparatus width direction toward the support member 118 passes through a circular through hole 118 </ b> C formed in the support member 118. Thereby, the upper part of the support member 118 is guided by the extended portion 202B and moves in the apparatus width direction.

  The lower support member 204 is formed in an L shape by bending a cylindrical bar, and a plurality of lower support members 204 are arranged at intervals in the apparatus depth direction. In the lower support member 204, the distal end side of the extending portion 204 </ b> B extending in the apparatus width direction toward the support member 118 passes through a circular through hole 118 </ b> D formed in the support member 118. As a result, the lower portion of the support member 118 is guided by the extending portion 204B and moves in the apparatus width direction.

  As described above, the support member 118 is moved in the apparatus width direction by the upper support member 202 and the lower support member 204.

  Further, a coil spring 212 constituting the urging mechanism 210 is disposed between the peripheral edge of the through hole 160D of the main body member 160 and the peripheral edge of the through hole 118A of the support member 118. The coil spring 212 urges the contact member 152 toward the inner peripheral surface of the fixing belt 102 via the support member 118.

  The urging forces of all the coil springs 186 are stronger than the urging forces of all the coil springs 212 in all states.

  In this configuration, by rotating the eccentric cam 182, as shown in FIGS. 12 and 13, the contact member 152 moves between the contact position and the separation position.

  The operation of the other second embodiment is the same as the operation of the first embodiment other than the operation exhibited by the urging mechanism 150 including the coil spring 166 disposed on the upper side and the coil spring 170 disposed on the lower side. It is the same.

  Although the present invention has been described in detail with respect to specific embodiments, the present invention is not limited to such embodiments, and various other embodiments can be taken within the scope of the present invention. This will be apparent to those skilled in the art. For example, in the intermediate position of the contact member 152 of the first embodiment, the upper part of the contact member 152 is in contact with the inner peripheral surface of the fixing belt 102, but the lower part of the contact member 152 is the inner part of the fixing belt 102. It may be in contact with the peripheral surface.

  Further, at the intermediate position of the contact member 152 of the first embodiment, the upper half of the contact member 152 is in contact with the inner peripheral surface of the fixing belt 102, but the contact member 152 and the inner peripheral surface of the fixing belt 102 are in contact with each other. The contact area may be determined based on the required belt heat amount.

  Moreover, in the said 1st Embodiment, although the intermediate position of the contact member 152 was only one place, multiple places may be sufficient.

  In the first embodiment, the contact member 152 is moved to the intermediate position. However, the contact member 152 may be moved only to the contact position and the separated position.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Image forming unit (an example of an image forming part)
100 fixing device 102 fixing belt (an example of an endless member)
118 Support member 150 Biasing mechanism (an example of a biasing member)
152 Contact member (an example of a moving member)
166 Coil spring (an example of a first biasing portion)
170 Coil spring (an example of a second urging portion)
180 Counter mechanism (example of counter member)
200 Fixing Device 210 Biasing Mechanism (Example of Biasing Member)
212 Coil spring

Claims (5)

A magnetic field generating member for generating a magnetic field;
An endless endless member that rotates partly on the outer peripheral surface of the magnetic field generating member, generates heat by electromagnetic induction of the magnetic field, and rotates,
A contact position that is disposed on the opposite side of the magnetic field generating member across the endless member, has an arc shape along the inner peripheral surface of the endless member, generates heat by electromagnetic induction of the magnetic field, and contacts the inner peripheral surface; A moving member that moves to a plurality of positions including a separation position that is spaced apart from the inner peripheral surface;
An urging member that urges the moving member so that the moving member moves to the contact position;
When the moving member is moved from the contact position to the separated position by applying a counter force that opposes the biasing force of the biasing member, and the counter force is released, the contact of the moving member A counter member allowing movement to a position;
A fixing device. The biasing member is
The first urging portion disposed on one end side of the moving member and a second urging portion disposed on the other end side of the moving member when viewed from the rotation axis direction of the endless member. The fixing device according to 1.   As viewed from the direction of the rotation axis of the endless member, across the moving member, on the side opposite to the magnetic field generating member, straddles the portion on one end side of the moving member and the portion on the other end side of the moving member. And a magnetic field generated by the magnetic field generating member and supporting the one end side portion of the moving member and the other end side portion of the moving member, transmitting the counter force of the counter member to the moving member. The fixing device according to claim 1, further comprising a support member that suppresses permeation. The moving member moves to the separation position, the contact position, and an intermediate position where a part of the moving member comes into contact with the inner peripheral surface,
The counter member imparts a part of the counter force to the moving member, so that the counter member moves the moving member from the contact position to the intermediate position, and the counter member further reduces the counter force. The fixing device according to any one of claims 1 to 3, wherein the counter member moves the moving member from the intermediate position to the separated position by applying another part to the moving member. An image forming unit for forming an image on a recording medium;
The fixing device according to any one of claims 1 to 4, wherein an image is fixed on a recording medium on which an image is formed by the image forming unit.
An image forming apparatus comprising:

Images