JP2011081148A - Damper device, separation/contact mechanism, fixing device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a separation/contact mechanism 30 of a simple configuration for a fixing roller 11 and a pressure roller 13. <P>SOLUTION: A damper device 50 includes: a shaft 52 supported so as to freely rotate; and a gear 51 held by the shaft 52 and having a one-way bearing 60 for applying a predetermined load to rotation of the shaft 52. The gear 51 rotates in one direction, thereby fixing the shaft 52, and also rotates in the opposite direction to the one-way direction, thereby holding the shaft 52 up to the predetermined load. If a load exceeding the predetermined load is applied, the gear 51 is idly rotated with constant idling torque. The separation/contact mechanism 30 includes: the damper device 50; a fixing roller 11 and a pressure roller 13, which serve as a separation/contact member; a cam 37 operated by the rotation of the gear 51; and a lever 32 moved by contact with the cam 37. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a damper device, a separation / contact mechanism, a fixing device, and an image forming apparatus.

  Conventionally, a power switching device used for a damper device, a separation / contact mechanism, a fixing device, and an image forming apparatus is arranged in parallel with a plurality of shafts that are rotatably supported and rotated in a predetermined direction. It is a power switching device having a one-way gear with a built-in one-way bearing that locks.

  For example, the following Patent Document 1 discloses a technology of a power switching device having a one-way gear with a built-in one-way bearing. Specifically, the first and second shafts, the first one-way gear incorporating the first one-way bearing, the second one-way gear incorporating the second one-way bearing, and the first one-way bearing incorporating the third one-way bearing. The power switching device further includes a first output gear that meshes with the first one-way gear, and meshes with the second one-way gear and the third one-way gear. And a second output gear and a motor coupled to the first shaft. The motor can be reversed in the forward and reverse directions so that the first gear can be rotated and stopped, and the second output gear can be rotated in the same direction.

Japanese Patent Laid-Open No. 8-152054

  However, the conventional damper device, separation / contact mechanism, fixing device, and image forming apparatus require a complicated configuration with a plurality of one-way bearings, and there is a problem that the size of the device increases.

  The damper device of the present invention includes a shaft portion that is rotatably supported, and a gear portion that is held by the shaft portion and includes a damper portion that applies a predetermined load to the rotation of the shaft portion. The part is characterized by holding the shaft part by rotating in one direction and holding the shaft part to a predetermined load by rotating in the direction opposite to the one direction.

  The separation / contact mechanism of the present invention includes the damper device and a separation / contact portion that holds at least two separation / contact members that are separated according to the rotation direction of the gear portion.

  The fixing device of the present invention includes the separation / contact mechanism, wherein the first separation / contact member is a fixing roller, and the second separation / contact member is a pressure roller.

  The image forming apparatus of the present invention includes the fixing device and a driving source that applies a driving force to the gear portion.

  According to the damper device of the present invention, when rotating in one direction, the shaft portion is locked and rotated, and when rotating in the direction opposite to the one direction, the wheel rotates idly with a constant idling torque. Can be transmitted to a predetermined load.

  According to the separation / connection mechanism of the present invention, the structure of the separation / connection mechanism 30 using rotation in two directions can be simplified by using the damper device.

  According to the fixing device and the image forming apparatus of the present invention, it is possible to reduce the size and cost of the apparatus as the structure of the separation / contact mechanism is simplified.

FIG. 1 is a perspective view illustrating a configuration of a separation / contact mechanism in the fixing unit according to the first exemplary embodiment. FIG. 2 is a block diagram showing an outline of the image forming apparatus in Embodiment 1 of the present invention. FIG. 3 is a cross-sectional view showing the configuration of the fixing unit in FIG. FIG. 4 is a perspective view showing the configuration of the fixing unit in FIG. FIG. 5 is a perspective view showing the configuration of the damper device in FIG. FIG. 6 is a cross-sectional view showing the internal configuration of the one-way bearing built in the one-way gear in FIG. FIG. 7 is an enlarged partial sectional view of FIG. 8 is a cross-sectional view taken along the line AA in FIG. FIG. 9 is an explanatory view showing the operation of the separation / contact mechanism in FIG. FIG. 10 is a perspective view showing the configuration of the damper device in FIG. FIG. 11 is a block diagram showing a modification of the damper device of FIG.

  Modes for carrying out the present invention will become apparent from the following description of the preferred embodiments when read in light of the accompanying drawings. However, the drawings are only for explanation and do not limit the scope of the present invention.

(Image Forming Apparatus of Example 1)
FIG. 2 is a cross-sectional view schematically illustrating the image forming apparatus according to the first embodiment of the present invention.

  The image forming apparatus is, for example, a printer, and corresponds to a sheet conveying unit 1 that conveys a recording medium P such as a sheet, a light emitting diode (hereinafter referred to as “LED”) head 3 as a recording light exposure member, and recording light. The toner image forming unit 2 is a developing device that forms a toner image, and the fixing unit 10 is a fixing device that fixes the toner image on the recording medium P. The toner image forming unit 2 and the fixing unit 10 are arranged in the order in which the recording medium P is conveyed. The LED head 3 is disposed adjacent to the toner image forming unit 2.

  In the image forming apparatus having such a configuration, when a print control unit (not shown) receives a print instruction, the paper transport unit 1 transports the recording medium P to the toner image forming unit 2 in accordance with the image formation timing. The LED head 3 irradiates the toner image forming unit 2 with recording light corresponding to the printing information, and the toner image forming unit 2 forms a toner image corresponding to the irradiated recording light on the recording medium P. Thereafter, when the recording medium P is conveyed to the fixing unit 10 by the paper conveying unit 1, the toner image on the recording medium P is fixed and discharged by the heat and pressure of the fixing unit 10. The operation of the image forming apparatus is controlled by a control unit (not shown).

(Fixing unit of Example 1)
FIG. 3 is a cross-sectional view showing the configuration of the fixing unit in FIG.

  The fixing unit 10 includes a fixing roller 11 that supplies heat to the recording medium P while conveying the print medium P, a heater 12 that serves as a heating unit that heats the fixing roller 11, a pressure roller 13 that serves as a pressure member, A heater 14 as a heating means for heating the pressure roller 13, a thermistor 15 as a temperature detection member for detecting the surface temperature of the fixing roller 11, and a thermistor 16 as a temperature detection member for detecting the surface temperature of the pressure roller 13. And have.

  Further, the fixing unit 10 includes a frame 17-1 that is a separating portion that holds the fixing roller 11 and the pressure roller 13. A toner image is formed by toner 4 on the recording medium P, and the recording medium P is conveyed from the medium conveyance direction X to the fixing unit 10.

FIG. 4 is a perspective view showing the configuration of the fixing unit in FIG.
The fixing unit 10 includes opposing frames 17-1 and 17-2 that are separation / contact portions, a rod member 18 that fits these upper portions, and a separation / detachment mechanism that is a release device provided on the frame 17-1 side. 30 and a fixing roller 11 and a pressure roller 13 which are separation members provided between the frames 17-1 and 17-2. The recording medium P is transported from the recording medium transport direction X.

  The fixing roller 11 is rotatably held by a frame 17-1 of the fixing unit 10 via a bearing. The pressure roller 13 is rotatably held via a bearing on a lever 32 that is rotatably held around the shaft portion 31 with respect to the frame 17-1. The roller 11 is disposed so as to be able to contact and separate. Further, in the first exemplary embodiment, when the printing operation is completed, the fixing unit 10 separates (releases) the pressure roller 13 as the second separation member from the fixing roller 11 as the first separation member. The rollers are configured to prevent deformation of the rollers due to constant pressure contact between the rollers.

  In the first embodiment, when performing the separation / contact operation of the fixing unit 10, this operation is performed in the separation / contact operation of the fixing roller 11 and the pressure roller 13 using switching of the rotation direction of the driving source that drives the fixing unit 10. By using the damper device of Example 1, switching of the driving direction with a simple configuration that does not require recombination of gears and the separation / contact mechanism 30 of each roller using the same are realized.

(Separation mechanism of Example 1)
FIG. 1 is a perspective view illustrating a configuration of a separation / contact mechanism in the fixing unit according to the first exemplary embodiment of the present invention.

  The separation / contact mechanism 30 has a function of controlling the pressure contact and separation of each roller in accordance with the rotation direction of the driving system of the fixing roller 11. The separation / contact mechanism 30 includes a gear 33 as a transmission member that transmits driving force and rotation from a driving source (not shown), and a gear 34 as a transmission member that transmits driving force and rotation from the gear 33. . In the first embodiment, the driving source is a stepping motor that can rotate in two directions.

  The gear 34 is a first separating member, and is provided so as to be coaxially fixed to the core of the fixing roller 11 as a fixing member. The rotation of the gear 34 is the rotation of the fixing roller 11. The separating / connecting mechanism 30 has a one-way gear 51 which is a transmission means for transmitting driving force and rotation from the gear 34. The one-way gear 51 is a damper portion (for example, a one-way bearing) 60 as a means for switching power. Built in. When the one-way bearing 60 is rotated in a predetermined direction, it locks and transmits the driving force. When the one-way bearing 60 is rotated in a direction opposite to the predetermined direction, a load greater than a predetermined load is applied to the shaft. So that the driving force is not transmitted by idling.

  The one-way gear 51 is rotatably supported with respect to the frame 17-1 of the fixing unit 10, and is supported by a shaft 52 that is a transmission support body for transmitting a driving force and rotation of the one-way bearing 60. . The separation / contact mechanism 30 further includes a gear 53 as a transmission member that transmits the driving force and rotation of the shaft 52 when the one-way bearing 60 rotates in the locking direction, and a transmission member that transmits the driving force and rotation of the gear 53. And a gear 35 as a transmission member for transmitting the driving force and rotation of the gear 54.

  The separation / contact mechanism 30 also transmits a driving force and rotation of the gear 35 as a separation / contact member, and a transmission unit that transmits the driving force and rotation of the shaft 36 as a transmission support that is rotatably supported. And a lever 32 as a support that rotatably supports the pressure roller 13 about a shaft 31, a cam 37 as a transmission position control body that controls the position of the lever 32, and a second separation / contact through the lever 32. And a spring 38 that is a biasing member that applies a load (biasing force) to the pressure roller 13 that is a pressure member.

  The cam 37 and the gear 35 are fixed to the shaft 36 by a lock pin. When the shaft 36 rotates, the cam 37 and the gear 35 rotate in the same direction. A positioning plate 39 is provided below the cam 37 in the vertical direction so as to come into contact with one cam end portion 37a of the fan-shaped cam 37 serving as a cam portion. The positioning plate 39 has an upstream end in the medium transport direction X fixed to the frame 17-1 of the separation / contact mechanism 30 in the fixing unit 10 and extends in the X direction. That is, the positioning plate 39 is provided so that the downstream end portion in the medium conveyance direction is movable by being deformed in the vertical direction (−Z direction) by a predetermined force applied by the cam 37.

  Note that one cam end portion 37a of the fan-shaped cam 37 first comes into contact with the positioning plate 39 when the cam 37 rotates in the direction of the arrow k in FIG. At this time, the cam 37 is in contact with the positioning plate 39, and the rotation in the direction of the arrow k is the direction in which the one-way gear 51 is idle, so that the driving force is not transmitted to the shaft 52, and only the one-way gear 51 is idle.

  Next, from the state in which the cam 37 and the positioning plate 39 are in contact with each other, the cam 37 and the positioning plate 39 are rotated by a predetermined amount in the direction of arrow d in FIG. Thus, the lever 32 rotates about the shaft 31 in the i direction, and the fixing roller 11 and the pressure roller 13 can be separated by a predetermined amount t. A contact position between the fan-shaped cam 37 and the lever 32 is set as a separation position 37 b of the cam 37. At this time, the pressing force direction C facing the lever 32 of the spring 38 via the lever 32, the cam 37, and the shaft 52 are aligned in a straight line, and the balance of the force relationship in the rotational direction of the cam 37 is equalized. The cam 37 is not rotated. In this state, unless the contact position between the cam 37 and the lever 32 is moved, that is, unless the cam 37 is rotated by an external force, the fixing roller 11 and the pressure roller 13 are maintained in a separated state.

  When the cam 37 is rotated in the direction of the arrow d from the state where the fixing roller 11 and the pressure roller 13 are separated from each other, the contact position of the cam 37 with respect to the lever 32 moves, and the pressing force direction of the spring 38 via the lever 32, The balance between the force portion of the cam 37 and the shaft 52 is lost, and the cam 37 is rotated by the pressing force of the spring 38 via the lever 32. As a result, the lever 32 rotates about the rotation shaft 31 in the h direction, and the pressure roller 13 and the fixing roller 11 come into contact with each other by moving the pressure roller 13 toward the fixing roller 11. When the cam 37 is separated from the lever 32, the lever 32 is rotated by the spring 38, and the pressure roller 13 is pressed against the fixing roller 11 by the urging force of the spring 38.

  The force necessary for the rotation of the cam 37, that is, the rotation of the shaft 52, is the force necessary for the rotation of the fixing roller 11 and the pressure roller 13 alone, or the force of the fixing roller 11 and the pressure roller 13 by the spring 38. It is determined from various factors such as the pressing force and the positional relationship between the rotation center of the lever 32 and the pressure roller 13. In the first embodiment, the force necessary for the rotation of the cam 37 is 90 gf · cm.

  Here, when the one-way gear 51 rotates in a direction opposite to one direction and idles, that is, when the fixing unit 10 rotates to convey the recording medium P in the medium conveying direction X, the drive source rotates in the forward direction. In other words, when the one-way gear 51 rotates and locks in one direction, that is, when the fixing unit 10 rotates the recording medium P in the opposite direction to the medium conveyance direction X shown in FIG. It is assumed that the drive source rotates in the reverse direction, that is, reverses when rotating in the direction in which the sheet is conveyed in the direction.

(Damper Device of Example 1)
FIG. 5 is a perspective view showing the configuration of the damper device in FIG. 1.

  The damper device 50 includes a one-way gear 51 with a built-in one-way bearing 60, a gear 53 as a transmission member that transmits the driving force and rotation of the shaft 52 when the one-way bearing 60 rotates in the locking direction, and the driving of the gear 53. A gear 54 is provided as a transmission member that transmits force and rotation, and a gear 55 is provided as a transmission member that transmits the driving force and rotation of the gear 54.

  In the first embodiment, the damper device 50 is necessary for rotating the cam 37 not only when the one-way gear 51 locks the shaft 52 but also when the one-way gear 51 rotates in the idling direction that is the reverse rotation. It is necessary to transmit more than a certain force. On the other hand, when the drive source rotates forward with the cam 37 in contact with the positioning plate 39, it is necessary to idle so that the cam 37 does not rotate. Further, the damper device 50 needs to be set so that the torque during idling is not less than the first predetermined value and not more than the second predetermined value. As described above, for the rotation of the cam 37, the separation / contact mechanism 30 of the first embodiment requires a driving force of 90 gf · cm, for example.

  Therefore, the damper device 50 according to the first embodiment generates, for example, a load of 100 gf · cm to 200 gf · cm, that is, a one-way as a driving force switching unit including a one-way bearing 60 that generates torque as a driving force. A gear 51 is provided. The torque during idling of the one-way bearing 60 is determined by the strength of the S-shaped leaf spring in the one-way gear 51.

  In the damper device 50 having such a configuration, the shaft 52 rotates together with the one-way bearing 60 when the one-way bearing 60 built in the one-way gear 51 rotates in the locking direction of the a ′ direction in FIG. The shaft 52 has a D-cut shape, has a similar D-cut shape hole, and has a gear 53 as a driving force rotation transmission means inserted into the shaft 52. The damper device 50 further has a gear 54 as a driving force rotation transmission means, a gear 55, and a shaft 56 that supports the gear 54, and the driving force and rotation of the gear 53 are transmitted to the gear 54.

(One-way gear of Example 1)
6 is a cross-sectional view showing an internal configuration of a wineway bearing built in the one-way gear in FIG. 5, and FIGS. 7A and 7B are enlarged partial cross-sectional views of FIG. 8 is a cross-sectional view taken along the line AA in FIG.

  A one-way bearing 60 is built in the one-way gear 51. Hereinafter, the elements that influence the idling torque characteristics of the one-way bearing 60 will be described in detail.

  6 and 7 (a) and 7 (b) are diagrams showing an example of the internal structure of the one-way bearing 60 built in the one-way gear 51. The one-way bearing 60 includes a housing 61, a sleeve 62, and a retainer. 63, a needle 64, and a spring 65 which is an S-shaped leaf spring. A shaft 52 is inserted into the hole of the one-way bearing 60.

  In FIG. 7A, when the housing 61 is rotated in the L direction, which is a counterclockwise direction, the needle 64 locks the shaft 52 and does not move relative to the housing 61. When locked. In FIG. 7B, when the housing 61 is rotated in the R direction, which is the clockwise direction, the needle 64 moves freely relative to the housing 61 with the shaft 52 free. When idling. That is, when the housing 61 is rotated in the counterclockwise direction, the needle 64 is pushed into the clamping portion as shown in FIG. The pressing force to press increases. Due to this pressing force, the needle 64 locks the rotation of the shaft 52. When the shaft 52 is locked, the shaft 52 cannot rotate relative to the housing 61. Therefore, the shaft 52 rotates counterclockwise with the housing 61.

  On the other hand, when the housing 61 is rotated in the clockwise direction, as shown in FIG. 7B, the needle 64 causes the spring 65 to bend along the sleeve 62 while bending the spring 65. Move in the direction. When the needle 64 moves in the direction of the spring 65 in this way, the needle 64 rotates as the housing 61 rotates. That is, since the needle 64 is not strongly pressed against the shaft 52, the needle 64 does not lock the relative rotation between the housing 61 and the shaft 52. The torque during idling is adjusted by the force that the spring 65 applies to the needle 64.

  FIG. 8 shows an example in which the spring 65 in FIGS. 7A and 7B has an S-shaped leaf spring shape. The force applied to the needle 64 is adjusted by adjusting the plate thickness, deformation amount, etc. of the spring 65, which is an S-shaped leaf spring. Further, when the S-shaped leaf spring is manufactured from a metal material using a metal mold, there is a portion where the flash surface side is outside the bending, and in order to increase the force applied to the needle 64 and to prevent it from breaking, It is necessary to adjust the material and shape of the leaf spring. In the first embodiment, the spring 65, which is an S-shaped leaf spring, is made of, for example, SUS304 and has a thickness of 0.2 mm, so that the torque during idling may be 100 gf · cm to 200 gf · cm. it can.

  In the first embodiment, the idling torque is determined from the torque for rotating the cam 37. However, it may be appropriately determined from the torque necessary for rotating the rotation target.

(Operation of the separation / contact mechanism of the first embodiment)
FIG. 9 is an explanatory view showing the operation of the separation / contact mechanism in FIG.

  During a printing operation, that is, when the fixing roller 11 and the pressure roller 13 are in contact with each other and rotating, a drive source (not shown) is rotated by a control unit (not shown) in a direction in which the one-way bearing 60 of the one-way gear 51 rotates idle. When the gear 33 shown in FIG. 1 rotates, the gear 34 rotates. As the gear 34 rotates, the fixing roller 11 fixed to the gear 34 rotates. The pressure roller 13 is a driven roller, and rotates by the rotation of the fixing roller 11 that is in contact therewith. At this time, the one-way gear 51 is driven in the idling direction with respect to the shaft 52, but can rotate the shaft 52 by idling torque.

  That is, the driving force is transmitted to the shaft 52 by the idling torque of the one-way gear 51 as long as the cam 37 is not inhibited from rotating by another member. That is, the cam 37 can rotate in the direction k in FIG. The rotation of the shaft 52 is sequentially transmitted to the gear 53, the gear 54, and the gear 35, and rotates the shaft 36 to which the gear 35 is fixed. By rotating the shaft 36, the cam 37 fixed to the shaft 36 is pressed against the positioning plate 39. Here, a state where the cam end portion 37a of the cam 37 and the positioning plate 39 are in contact with each other is referred to as a home position.

  During normal printing, the drive source continues to rotate forward, and the fixing roller 11 rotates in the direction in which the recording medium P is conveyed to rotate the gear 34. Since the cam end portion 37a of the cam 37 and the positioning plate 39 are in contact with each other, the rotation of the cam 37 is inhibited, and the required torque of the cam 37 greatly exceeds, for example, an idling torque of 200 gf · cm. Starts idling, and the cam 37 cannot rotate more than the state in contact with the positioning plate 39. Therefore, during the printing operation, as shown in FIG. 9A, the cam 37 is always kept at the home position. At this time, the fixing roller 11 and the pressure roller 13 are pressed against each other by the spring 38.

  Next, an operation after printing is completed will be described. When printing is completed, the fixing unit 10 moves to a release position in which the fixing roller 11 and the pressure roller 13 are separated by the separation / contact mechanism 30.

The drive source starts rotating in the reverse direction to that during the printing operation.
In FIG. 1, the rotation of the drive source (not shown) rotates the gear 33, so that the fixing roller 11 also starts reverse rotation. At this time, since the one-way gear 51 rotates in the direction in which the shaft 52 is locked, the shaft 52 is reliably locked and the shaft 52 is rotated. The rotation of the shaft 52 rotates the gear 53, the gear 54, and the gear 35, and further rotates the shaft 36 and the cam 37 that are fixed to the gear 35 in the direction d, which is the reverse direction to the previous printing operation.

  In FIG. 9B, the cam 37 rotates in the d direction. As a result, the cam 37 pushes the lever 32 against the urging force of the spring 38 in the direction of arrow e in FIG. Therefore, the pressure roller 13 fixed to the lever 32 is separated from the fixing roller 11 in the f direction. In this transition to the release position, the position of the cam 37 is brought into contact with the positioning plate 39 during the printing operation so that it is positioned at the reference home position, and the one-way gear 51 locks the shaft 52. Therefore, the fixing roller 11 and the pressure roller 13 are surely moved each time by rotating the cam 37 by a predetermined amount by rotating the driving source by a predetermined amount and reversely from the time of printing. A fixed amount can be separated. The state in which the fixing roller 11 and the pressure roller 13 are separated is referred to as a roller release state. This roller release state is maintained unless a rotational drive is applied to the cam 37 next due to the shape of the cam 37 and the balance between the biasing force of the lever 32 and the spring 38.

  Next, an operation when resuming printing will be described. When the control unit of the image forming apparatus receives the print data, the control unit reverses the drive source by a predetermined amount. In the reverse operation, the cam 37 is rotated in the direction of the arrow d in FIG. In the process of rotating the cam 37 by a predetermined amount, the cam 37 further rotates in the direction of the arrow d in FIG. To do. The lever 32 rotates in the direction of arrow g in FIG. 9C by the biasing force of the spring 38, and moves the pressure roller 13 in the j direction to contact the fixing roller 11. Next, the control unit rotates the drive source in the normal direction so that the cam 37 shifts to the home position and starts printing.

  As described above, by using the locking of the one-way gear 51 by the damper device 50 and the idling torque, it is possible to switch the driving direction with a simple configuration that does not require a complicated gear arrangement and configuration for switching the gears and switching the gears. And the separation / contact mechanism 30 of the fixing roller 11 and the pressure roller 13 using the same is realized.

(Effect of Example 1)
According to the damper device 50 of the first embodiment, the idling is performed with a constant idling torque during normal rotation, and the shaft portion 52 is locked and rotated during reverse rotation, so that transmission of driving force from the driving source is transmitted to a predetermined load. be able to.

  According to the separating / connecting mechanism 30 of the first embodiment, the amount of rotation of the gear 53 is controlled by using the damper device 50 described above even when a force is applied in the direction in which the one-way bearing 60 of the one-way gear 51 runs idle. Made it possible. In addition, the structure of the separation / contact mechanism 30 using rotation in two directions can be simplified.

  According to the fixing device 10 and the image forming apparatus of the first embodiment, as the structure of the separation / contact mechanism 30 is simplified, it is possible to reduce the size and cost of the apparatus.

(Damper Device of Example 2)
The configuration of the second embodiment of the present invention is the same as that of the first embodiment except for the configuration of the damper device 50A. Hereinafter, the damper device 50A according to the second embodiment will be described.

  In the first embodiment, the idling torque of the one-way gear 51 is set to an arbitrary constant value so that the driving force can be transmitted up to a predetermined amount. However, the one-way gear 51 has been reduced in size, and there is a limit to the space in which the spring 65, which is an S-shaped leaf spring, can be stored, and the amount of deformation and stress of the spring 65 with respect to the thickness of the leaf spring increases. Since there is a problem of reducing the durability of the spring, it is difficult to increase the idling torque generated when rotating to the idling side.

  Therefore, in the second embodiment, the idling torque of the one-way gear 51A is reduced and only the idling torque generating portion is separated.

  FIGS. 10A and 10B are perspective views illustrating the configuration of the damper device in FIG. 1 according to the second embodiment.

  10A, the damper device 50A has a one-way gear 51A incorporating a small one-way bearing 60A having a torque during idling of 30 gf · cm or less. Further, the one-way gear 51A has a shaft 52A as a driving force rotation transmission means that rotates together with the one-way bearing 60A when rotating in the locking direction of the one-way bearing 60A. The shaft 52A has a D-cut shape, and a gear 53A having a similar D-cut shape hole is inserted into the D-cut shape portion. A torque limiter 57 having a torque of 100 gf · cm or more is attached to the shaft 52A.

  In FIG. 10B, the gear 53 </ b> A transmits driving force and rotation to the gear 54. The gear 53A is locked to the shaft 52A by a pin 52a. The torque limiter 57, which is an idling torque generator and a load generator, has a bearing portion 55a, and the torque limiter 57 and the shaft 52A are fixed by a fixing portion 55c provided in the bearing portion 55a. Further, the exterior portion 55b of the torque limiter 57 is fixed by fitting the fixing portion 55d to the one-way gear 51A.

  The bearing portion 55a of the torque limiter 57 is disposed so as to be rotatable with respect to the exterior portion 55b via a load generating portion 55e. Therefore, the rotation of the exterior portion 55b with respect to the bearing portion 55a is given a predetermined amount of load by the load generating portion 55e. In the second embodiment, as described above, for example, a load of 100 gf · cm or more is generated. In the second embodiment, the load generating unit 55e employs the torque limiter 57 with a built-in spring, but it is also possible to employ a load adjustment based on oil viscosity.

  The operation of the damper device 50A having such a configuration is the same as that of the first embodiment. That is, in FIG. 10, when the one-way bearing 60A built in the one-way gear 51A rotates in the locking direction, the shaft 52A rotates together with the one-way bearing 60A. The shaft 52A has a D-cut shape, and has a gear 53A as a driving force rotation transmission means that has a similar D-cut shape hole and is inserted into the shaft 52A. The damper device 50 </ b> A further has a gear 54 as a driving force rotation transmission means, a gear 55, and a shaft 56 that supports the gear 54, and the driving force and rotation of the gear 53 are transmitted to the gear 54.

(Effect of Example 2)
According to the second embodiment, in addition to the effects of the first embodiment, since idling torque is generated by the torque limiter 57, the structure of the one-way gear 51A is more complicated than the first embodiment. A large idling torque can be generated. Even when the torque required for the rotation of the cam 37 is relatively large, the cam 37 can be rotated by the idling torque by the torque limiter 57. In addition, since the torque limiter 57 that is the idling torque generator is separated from the one-way gear 51A, the torque generated by the S-shaped leaf spring in the one-way gear 51A can be weakened. For this reason, since the S-shaped leaf spring stress can be reduced, the life of the S-shaped leaf spring can be extended. Accordingly, the life of the one-way gear 51A is extended. In addition, in order to enable control of the load of the torque limiter 57 alone, by ensuring the performance of the torque limiter 57 alone, it is possible to stabilize the idling torque and improve the reliability of the idling torque until the life of the device. Can do.

(Modification of Example 2)
FIG. 11 is a configuration diagram showing a modification of the damper device of FIG.

  For example, a one-way gear 51B having a built-in one-way bearing 60B having a torque during idling of 30 gf · cm or less is provided. Further, the one-way gear 51B has a shaft 52B that rotates together with the one-way bearing 60B when rotating in the locking direction of the one-way bearing 60B. The shaft 52B has a D-cut shape, and a gear 53B having a similar D-cut shape hole is inserted into the D-cut shape portion. Further, there is one or a plurality of plates 71 between the gear 53B and the gear 51B, and a plurality of washer 72 having a convex portion for applying a load is inserted between the plates 71. In order to set the torque of the shaft 52B in the direction in which the one-way bearing 60B idles in the gap between the plates 71 to 100 gf · cm or more and 200 gf · cm or less, for example, stoppers are provided on both sides of the gear 53B and the one-way gear 51B. A retaining ring 73 is attached. In this modification, two wave washers 72 are used. The load generated by the wave washer 72 transmits the driving force and the rotational force to the gear 54. That is, the idling torque is determined by the thickness of the wave washer 72 (0.2 mm in the present modification), the height of the convex portion, and the interval between the plates 71 (= tmm).

  The operation of the damper device 50B having such a configuration is the same as that of the first embodiment. That is, in FIG. 11, when the one-way bearing 60B built in the one-way gear 51B rotates in the locking direction, the shaft 52B rotates together with the one-way bearing 60B. The shaft 52B has a D-cut shape, has a similar D-cut shape hole, and has a gear 53B as driving force rotation transmission means inserted into the shaft 52B. The damper device 50 </ b> B further includes a gear 54, a gear 55, and a shaft 56 that supports the gear 54 as driving force rotation transmission means, and the driving force and rotation of the gear 53 are transmitted to the gear 54.

(Other variations of Examples 1 and 2)
The present invention is not limited to the above-described embodiments, and various usage forms and modifications are possible. For example, the following forms (a) to (d) are used as the usage form and the modified examples.

  (A) Although the fixing device 10 that contacts and contacts the roller according to the change in the driving direction has been described as an example, the fixing device 10 can be applied to many devices as long as the device contacts and contacts by driving. The photosensitive member and the transfer portion may be brought into contact with each other to form a toner image on the medium, and the photosensitive member and the transfer portion may be separated from each other by being driven in the reverse direction. .

  (B) Although the image forming apparatus 1 has been described using an example applied to a printer, it can be used not only for a printer but also for a copying machine, a facsimile, an MFP, and the like.

(C) As the recording medium P, in addition to plain paper, OHP sheets, cards, postcards, special paper such as thick paper having a weight equivalent to 200 / m ² or more, envelope, coated paper having a large heat capacity, and the like can be used.

  (D) The fixing device 10 may be integrally attached to the image forming apparatus or may be removable from the image forming apparatus.

DESCRIPTION OF SYMBOLS 1 Paper conveyance part 2 Toner image formation part 3 LED head 4 Toner 10 Fixing unit 11 Fixing roller 13 Pressure roller 17-1, 17-2 Frame 30 Separation / contact mechanism 31 Shaft part 32 Lever 32a Contact part 33, 34, 35 Gear 36 shaft 37 cam 37a cam end 38 spring 39 positioning plate 50, 50A, 50B damper device 51, 51A, 51B one-way gear 52, 52A, 52B shaft 53, 53A, 53B gear 54, 55 gear 56 shaft 57 torque limiter 60 One-way bearing 61 Housing 62 Sleeve 63 Retainer 64 Needle 65 Spring 71a, 71b Plate 72 Wave washer 73 Retaining ring
P Recording medium

Claims (15)

A shaft part rotatably supported;
A gear portion having a damper portion that is held by the shaft portion and applies a predetermined load to the rotation of the shaft portion;
The gear portion is
A damper device characterized by holding the shaft portion by rotating in one direction and holding the shaft portion to a predetermined load by rotating in a direction opposite to the one direction.   2. The damper device according to claim 1, wherein the gear portion includes a damper portion that idles at a constant load when a load is applied beyond the predetermined load.   The damper device according to claim 2, wherein the constant load is 100 gf · cm or more.   The damper device according to claim 2 or 3, wherein the damper portion is a one-way bearing. The damper device is
A gear portion having a one-way bearing whose load is equal to or lower than the first load;
The damper device according to claim 1, further comprising: a damper portion mounted on the shaft portion, the load of which is equal to or greater than the second load.   The damper device according to claim 5, wherein the first load is 30 gf · cm, and the second load is 100 gf · cm.   The damper device according to claim 5, wherein the damper unit is a torque limiter.   The damper device according to any one of claims 2 to 7, wherein the damper portion includes a spring that generates the idling torque. The damper device according to claim 1 or 2,
A separation / contact portion for holding at least two separation / contact members according to the rotation direction of the gear portion;
A separation / contact mechanism characterized by comprising: The separation part is
A cam portion that operates by rotation of the gear portion;
A lever portion that moves by contact with the cam portion;
The separation / contact mechanism according to claim 9, wherein:   The gear portion rotates in the opposite direction, thereby rotating the cam portion with the constant load to contact the separating member, and further rotating in the one direction to hold the shaft portion. The contact / separation mechanism according to claim 10, wherein the cam portion is rotated, the lever portion is brought into contact with and pressed, and the separation member is separated. A separation / contact mechanism according to any one of claims 9 to 11, comprising:
The first separating member is a fixing member;
The fixing device according to claim 2, wherein the second contact member is a pressure member. The fixing member is a fixing roller;
The fixing device according to claim 12, wherein the pressure member is a pressure roller. A fixing device according to claim 12 or 13,
A driving source for applying a driving force to the gear portion;
An image forming apparatus comprising:   The image forming apparatus according to claim 14, wherein the driving source is a stepping motor that is rotatable in one direction and two opposite directions.

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