JP5121879B2 - Fixing device and image forming apparatus including the same - Google Patents

Description

  The present invention relates to a fixing device that fixes a toner image formed on a recording sheet and an image forming apparatus including the same.

  This type of fixing device is applied to an image forming apparatus such as an electrophotographic method, an electrostatic recording method, and a magnetic photographic method, and uses a recording paper (plain paper, electrostatic recording paper, photographic paper, etc.) to which a toner image is transferred. It is sandwiched between a pair of fixing rotation members (belts and rollers) and heated and pressurized to fix the toner image on the recording paper.

  In such a fixing device, since the peripheral surface of the fixing rotation member is contaminated with toner or the like, it is necessary to clean the peripheral surface of the fixing rotation member with a blade, a felt, a web sheet, or the like. In addition, when the processing speed of the image forming apparatus is high and the number of printed sheets per unit time is large, the fixing rotating member of the fixing device becomes dirty, and cleaning of the fixing rotating member with a blade or a felt is required. Cleaning with a web sheet is often employed because the dirt cannot be removed.

  For example, in Patent Document 1, a web sheet is sent out from a supply roller, the web sheet is taken up on a take-up roller, and the web sheet is pressed against a fixing roller in the middle from sending out to take-up. Are cleaning. Further, the take-up roller is driven by a motor to rotate at a low speed, and the web sheet is taken up and sent out.

  Moreover, in patent document 2, in order to drive the winding roller which winds up a web sheet, the web drive solenoid is used.

JP-A-8-185074 JP-A-9-197884

  However, even if the cleaning by the web sheet is employed to effectively remove the fixing rotating member, a motor for rotating the web sheet take-up roller at a low speed as in Patent Documents 1 and 2 Providing a solenoid caused an increase in power consumption and cost compared to blades and felts.

  For this reason, it is conceivable that a motor for rotating the fixing rotation member is also used for rotating the web sheet take-up roller. In this case, the rotation speed of the web sheet take-up roller is very low as compared with the fixing rotation member, so that a large reduction ratio is required.

  However, in the configuration in which the distance between the shafts of the fixing rotation members is changed, the positional relationship between the shaft of the fixing rotation member and the shaft of the web sheet take-up roller also changes. It has been difficult to construct a power transmission mechanism that can rotate the web sheet take-up roller together and that can sufficiently increase the reduction ratio of the web sheet take-up roller.

  Accordingly, the present invention has been made in view of the above-described conventional problems, and the rotation member for fixing and the web sheet take-up roller can be rotated at appropriate rotation speeds using one drive source. And a fixing device capable of rotating both the fixing rotary member and the web sheet take-up roller even if the positional relationship between the axis of the fixing rotary member and the axis of the web sheet take-up roller changes, and the fixing device An object of the present invention is to provide an image forming apparatus including the above.

In order to solve the above-described problems, a fixing device according to the present invention includes a fixing rotating member and a roller that are pressed against each other, a rotation driving unit that rotates the fixing rotating member and the roller , and the fixing rotating member or roller. A cleaning web sheet roller that winds or sends out a cleaning web sheet that cleans the peripheral surface of the roller, and includes a swing cam that is rotationally driven by the rotation driving means, and the cleaning web sheet roller. A rotation transmitting means for transmitting a rotational driving force; a one-way clutch provided on an input shaft of the rotation transmitting means; a swing lever connected to the one-way clutch and urged so as to slidably contact the swing cam; , said fixing rotary member and the roller and first and second frames respectively pivotally supported, the pressure contact state of the fixing rotary member and the roller and圧解shape The second frame is supported so as to be displaceable with respect to the first frame, and the swing cam and the swing lever are provided on the first and second frames, respectively. Regardless of the displacement position of the frame, when the swing lever of the second frame is in sliding contact with the swing cam of the first frame and the swing cam is rotated by the rotation driving means, the swing cam slides on the swing cam. The rocking lever in contact with the rocking lever is repeatedly rocked, and the rocking of the rocking lever is transmitted as an intermittent rotation in one direction to the input shaft of the rotation transmitting means via the one-way clutch. It is transmitted to the cleaning web sheet roller through a rotation transmitting means.

In such a fixing device of the present invention , the fixing rotation member and the roller are displaced by displacing the second frame with respect to the first frame, that is, by displacing the axis of the roller relative to the axis of the fixing rotation member. It is possible to switch between the pressure contact state and the pressure state.

  In this case, the positional relationship between the swing lever and the swing cam also changes. However, if the swing lever is in sliding contact with the swing cam, the swing lever swings with the rotation of the swing cam. Therefore, the rotational driving force can be transmitted from the swing cam to the swing lever to rotate the cleaning web sheet roller.

  Further, since the rotation of the swing cam becomes the swing of the swing lever, and the swing of the swing lever is transmitted as an intermittent rotation in one direction via the one-way clutch, a large reduction ratio can be obtained.

  In the fixing device of the present invention, the second frame is provided with retracting means for retracting and retracting the swing lever from the swing cam.

  When the swing lever is moved away from the swing cam, the swing lever stops, so that the cleaning web sheet roller stops, and the cleaning web sheet winding and feeding are stopped.

  Furthermore, in the fixing device of the present invention, the swing lever, the one-way clutch, the rotation transmission means, and the cleaning web sheet roller are provided on the second frame.

  In this case, the swing lever, the one-way clutch, the rotation transmission means, and the cleaning web sheet roller are displaced together with the second fixing rotation member of the second frame.

  Next, an image forming apparatus of the present invention includes the fixing device of the present invention. Even in such an image forming apparatus, the same effects as those of the fixing apparatus of the present invention are achieved.

  According to the present invention, the rotation of the swing cam is the swing of the swing lever (reciprocal rotation), and the swing of the swing lever is transmitted as an intermittent rotation in one direction via the one-way clutch. Therefore, a large reduction ratio can be obtained.

  Further, the positional relationship between the shaft of the fixing rotation member on the rotation driving means side and the shaft of the cleaning web sheet roller on the rotation transmission means side changes, and the positional relationship between the swing lever and the swing cam changes. As long as the swing lever is in sliding contact with the swing cam, the swing lever swings as the swing cam rotates, and the rotational driving force is transmitted from the swing cam to the swing lever. The cleaning web sheet roller rotates.

1 is a cross-sectional view illustrating an image forming apparatus to which an embodiment of a fixing device of the present invention is applied. FIG. 2 is a cross-sectional view illustrating a fixing device of the present embodiment. FIG. 4 is a side view schematically showing the positional relationship between the shafts of the rollers in the fixing device of the present embodiment. FIG. 5 is a side view schematically showing a gear of each roller shaft and another gear group in the fixing device of the present embodiment. FIG. 3 is a front view illustrating a configuration of a rotation transmission unit in the fixing device of the present embodiment. (A) is a side view showing a first frame, a second frame, a unit frame and the like in the fixing device of the present embodiment, and (b) shows a state in which the second frame is displaced with respect to the first frame. It is a side view, (c) is a side view which shows the state which removed the 2nd frame from the 1st frame. (A)-(d) is a side view which shows the operation | movement of a rocking lever in the press contact state which made the press roller and the fixing belt press-contact. (A) is a side view showing a rocking angle of a rocking lever in a pressure contact state in which a pressure roller and a fixing belt are in pressure contact, and (b) is a state where the pressure roller is slightly brought into contact with the fixing belt. It is a side view which shows the rocking | fluctuation angle of the rocking | fluctuation lever in an uncompressed state. It is a side view which shows the state which spaced apart and retracted the rocking lever.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is an enlarged cross-sectional view showing a main part of an image forming apparatus to which an embodiment of a fixing device of the present invention is applied. The image forming apparatus 1 is based on electrophotography, and includes a photosensitive drum 2, a transfer belt 3, a fixing device 4, and the like. The photosensitive drum 2 has a photosensitive layer on its surface and is driven to rotate in the direction of arrow A at a constant rotational speed. As the photosensitive drum 2 rotates, the surface of the photosensitive drum 2 is uniformly charged to a predetermined potential by a charging device (not shown), and the surface of the photosensitive drum 2 is exposed by an exposure device (not shown). Then, an electrostatic latent image is formed on the surface thereof, and the electrostatic latent image on the surface of the photosensitive drum 2 is developed into a toner image by a developing device (not shown).

  The transfer belt 3 is driven to rotate in the direction of arrow B at the same speed as the surface speed of the photosensitive drum 2 and is pressed against the photosensitive drum 2 to form a nip region therebetween. The recording paper P conveyed from below is introduced into the nip area, and the toner image on the surface of the photosensitive drum 2 is transferred to the recording paper P while the recording paper P is conveyed in the nip area. A high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the transfer belt 3 in order to transfer the toner image.

  The recording paper P is conveyed upward and guided to the fixing device 4 where it is heated and pressurized to fix the toner image on the recording paper P. The recording paper P is further conveyed upward through the conveyance path 5 and discharged to a paper discharge tray (not shown).

  FIG. 2 is a cross-sectional view showing the fixing device 4 of the present embodiment. As shown in FIG. 2, the fixing device 4 includes a pressure roller 11, a heating roller 12, a heating auxiliary roller 13, and an endless fixing belt 14 that is stretched between the heating roller 12 and the heating auxiliary roller 13. The pressure roller 11 and the heating roller 12 are pressed against each other via the fixing belt 14 to form a nip area N between the fixing belt 14 and the pressure roller 11.

  The pressure roller 11 is a three-layer roller in which an elastic layer is provided on the outer surface of the hollow shaft, and a release layer is formed on the outer surface of the elastic layer. Inside the pressure roller 11 (inside the hollow shaft), a heater lamp (halogen lamp) as a heat source for heating the roller 11 is provided.

  The heating roller 12 is provided with an elastic layer on the outer surface of the hollow shaft, but the elastic layer is sufficiently thick.

  The fixing belt 14 is an endless belt made of a material having good heat conduction, and has a release layer on the outer peripheral surface thereof.

  The auxiliary heating roller 13 is provided with a surface layer on the outer surface of the hollow shaft, and a heater lamp (halogen lamp) as a heat source for heating the roller 13 is provided inside the auxiliary heating roller 13 (inside the hollow shaft). It has been.

  Here, since the elastic layer of the heating roller 12 is sufficiently thick, when the pressure roller 11 and the heating roller 12 are pressed against each other via the fixing belt 14, the elastic layer of the heating roller 12 is greatly recessed. Thus, a wide nip area N is formed between the fixing belt 14 and the heating roller 12. When each of the rollers 11, 12, 13 is rotated in the direction of the arrow, the fixing belt 14 is heated by the auxiliary heating roller 13 and rotates around the nip region N. In this state, when the recording paper is conveyed through the nip area N, the recording paper is heated and pressed by the fixing belt 14 and the pressure roller 11 to fix the toner image on the recording paper.

  On the other hand, the fixing device 4 includes a cleaning unit 6 that cleans the peripheral surface of the pressure roller 11. The cleaning unit 6 includes a feed roller 22 around which a web sheet 21 made of a thin (around 100 μm thickness) cloth impregnated with oil (silicon oil or the like) is wound, a take-up roller 23 to which the tip of the web sheet 21 is connected, A plurality of tension rollers 24 that bridge the web sheet 21 that is fed from the feed roller 22 and wound around the take-up roller 23, and the web sheet 21 is pressed against the pressure roller 11 between the feed roller 22 and the take-up roller 23. A pressure contact roller 25. The web sheet 21 is pressed against the surface of the pressure roller 11 by the pressure roller 25, and the adhered toner adhering to the surface of the pressure roller 11 is wiped off by the web sheet 21.

  The web sheet 21 is wound up little by little by the take-up roller 23 and sent out from the feed roller 22 little by little according to the number of recording sheets to be printed, the printing processing time, and the toner consumption. Thereby, the part of the web sheet 21 in the nip area between the pressure roller 25 and the pressure roller 11 is updated, and the cleaning ability by the web sheet 21 is maintained.

  By the way, in such a fixing device 4, it is preferable that the driving source of the pressure roller 11 and the heating roller 12 for fixing is also used for rotating the feed roller 22 and the take-up roller 23 of the web sheet 21. Since the rotational speeds of the rollers 22 and 23 of the web sheet 21 are very low compared to the rotational speeds of the fixing rollers 11 and 12, a large reduction ratio is required.

  Further, as will be described in detail later, in order to switch and set a pressure contact state in which the fixing rollers 11 and 12 are pressed and a pressure disengagement state in which the pressure between the fixing rollers 11 and 12 is released, the fixing is performed. The distance between the axes of the rollers 11 and 12 is changed. As the distance between the axes changes, the positional relationship between the shafts of the fixing rollers 11 and 12 and the shafts of the rollers 22 and 23 of the web sheet 21 also changes. These rollers 11, 12, 22, and 23 need to be rotated together. For example, when printing a thick letter or the like, the fixing rollers 11 and 12 are set in a pressed state. At this time, the fixing rollers are used to clean the peripheral surface of the pressing roller 11. It is preferable to rotate not only the rollers 11 and 12 but also the rollers 22 and 23 of the web sheet 21.

  Therefore, in the present embodiment, the fixing rollers 4 and 12 of the fixing device 4 are rotationally driven by the drive source of the image forming apparatus, and the fixing rollers are used by using the cam, the swing lever, and the one-way clutch. 11, 12 is greatly decelerated and transmitted to the rollers 22, 23 of the web sheet 21, and the fixing rollers 11, 12, regardless of changes in the distance between the axes of the fixing rollers 11, 12, 12 and the rollers 22 and 23 of the web sheet 21 are rotated together.

  Next, the rotation drive mechanism using such a cam, a swing lever, and a one-way clutch will be described in detail.

  3 shows the shaft 11a of the pressure roller 11, the shaft 12a of the heating roller 12, the shaft 13a of the auxiliary heating roller 13, the shaft 22a of the feed roller 22, the shaft 23a of the take-up roller 23, each tension roller 24, and the pressure roller. It is a side view which shows typically the positional relationship of the axis | shaft 25a of 25. FIG.

  4 shows the shaft 11a of the pressure roller 11, the shaft 12a of the heating roller 12, the shaft 22a of the feed roller 22, and the gears 11G, 12G, 22G, and 23G fixed to the shaft 23a of the take-up roller 23. FIG. 4 is a side view schematically showing other gears and the like that transmit rotation to the gears 11G, 12G, 22G, and 23G.

  Here, the driving sources of the fixing rollers 11 and 12 of the fixing device 4 and the rollers 22 and 23 of the web sheet 21 are provided on the image forming apparatus 1 side, and the fixing device 4 is connected to the image forming apparatus 1. When the image forming apparatus 1 is detachably mounted, the output shaft gear (not shown) that is rotationally driven on the image forming apparatus 1 side meshes with the input gear 31G of the input shaft of the fixing device 4, and the input gear 31G Driven by rotation.

  When the input gear 31G is rotationally driven, the small gear 31g fixed to the input gear 31G is rotationally driven, and the gear 11G of the pressure roller 11 that meshes with the small gear 31g rotates in the direction of the arrow. Also rotate in the same direction.

  When the input gear 31G is driven to rotate, the gear 32G meshed with the input gear 31G and the small gear 32g fixed to the gear 32G rotate, and the gear 12G of the heating roller 12 meshed with the small gear 32g Rotate in the direction. A one-way clutch (not shown) is interposed between the gear 12G and the shaft 12a of the heating roller 12. As long as the rotational driving force of the pressure roller 11 is transmitted to the heating roller 12 via the fixing belt 14 and the heating roller 12 is driven to rotate, the gear 12G is transferred to the shaft 12a of the heating roller 12 via the one-way clutch. Only when the rotational torque is not transmitted and the fixing belt 14 or the heating roller 12 slips and the rotation speed of the heating roller 12 decreases, the one-way clutch is locked, and the heating roller 12 passes through the one-way clutch from the gear 12G. The rotational torque is transmitted to the shaft 12a, and the rotation delay of the heating roller 12 is prevented.

Further, the speed of the peripheral surface of the pressure roller 11 and the speed of the peripheral surface of the fixing belt 14 are set to be substantially the same, and the recording paper is conveyed upward through the nip region N between the pressure roller 11 and the fixing belt 14. Is done.

Further, the gear 33G meshing with the gear 32G and the small gear 33g fixed to the gear 33G rotate, the gear 34G meshing with the small gear 33g rotates, the cam gear 35G meshing with the gear 34G rotates, and the cam gear A rocking cam 36 fixed to 35G rotates in the direction of the arrow.

The swing lever 37 is biased counterclockwise around a shaft 39 by a spring 38 and is in contact with the peripheral surface of the swing cam 36. A first one-way clutch 41 that transmits only the clockwise rotation of the swing lever 37 to the shaft 39 is interposed between the swing lever 37 and the shaft 39.

Since the swing lever 37 is biased by the spring 38 and is in contact with the swing cam 36, when the swing cam 36 rotates, the swing lever 37 swings (reciprocates) as indicated by an arrow C. With this swing, only the clockwise rotation of the swing lever 37 is transmitted to the shaft 39 through the first one-way clutch 41, and the shaft 39 rotates intermittently in the clockwise direction. For example, every time the swing cam 36 rotates once, the shaft 39 rotates about 7.5 ° to 15 °. A large reduction ratio is obtained by the combination of the swing cam 36 and the swing lever 37.

  The rotation of the shaft 39 is transmitted to the gear 23G while being further decelerated by the rotation transmission unit GU, and the take-up roller 23 rotates at a low speed in the direction of the arrow. As a result, the web sheet 21 is wound little by little on the take-up roller 23, the web sheet 21 is fed little by little from the feed roller 22, and the feed roller 22 is driven to rotate.

  FIG. 5 is a front view schematically showing the configuration of the rotation transmission unit GU. In the rotation transmission unit GU, a first one-way clutch 41 is interposed between the swing lever 37 and one end of the shaft 39. The other end of the shaft 39 is pivotally supported by the second one-way clutch 42, and the second one-way clutch 42 is fixed to the frame of the rotation transmission unit GU.

  As described above, only the clockwise rotation of the swing lever 37 is transmitted to the shaft 39 through the first one-way clutch 41. At this time, the second one-way clutch 42 becomes free and the shaft 39 rotates clockwise. Rotate in the direction. Further, when the swing lever 37 rotates counterclockwise and returns, the first one-way clutch 41 becomes free, but a slight rotational torque in the counterclockwise direction is applied to the shaft 39 via the first one-way clutch 41. Since there is a possibility that the shaft 39 rotates in the counterclockwise direction when transmitted, the second one-way clutch 42 prohibits the rotation of the shaft 39 in the counterclockwise direction. Therefore, the combination of the first and second one-way clutches 41 and 42 ensures that the shaft 39 rotates intermittently in the clockwise direction.

  The shaft 39 is provided with five gears 44g, 45G, 45g, 46G, and 46g. The small gear 44 g is fixed to the shaft 39 and rotates together with the shaft 39. The gear 45G and the small gear 45g are fixed to each other and supported rotatably around the shaft 39. The gear 46G and the small gear 46g are also fixed to each other and supported rotatably around the shaft 39.

  The shaft 23a of the winding roller 23 is also provided with five gears 47G, 47g, 48G, 48g, and 23G. The gear 23G is fixed to the shaft 23a of the take-up roller 23 and rotates together with the shaft 23a of the take-up roller 23. The gear 47G and the small gear 47g are fixed to each other and supported rotatably around the shaft 23a. The gear 48G and the small gear 48g are also fixed to each other and supported rotatably around the shaft 23a.

  The gears 44g, 45G, 45g, 46G, 46g of the shaft 39 and the gears 47G, 47g, 48G, 48g, 23G of the shaft 23a mesh with each other. When the shaft 39 rotates in the clockwise direction, the small gear 44g fixed to the shaft 39 rotates, and this rotation causes the gear 47G and the small gear 47g → the gear 45G and the small gear 45g → the gear 48G and the small gear 48g → the gear 46G and the small gear. The gear 46g → the gear 23G is transmitted and decelerated, the gear 23G and the shaft 23a fixed to the gear 23G rotate at a low speed, and the winding roller 23 also rotates at a low speed in the direction of the arrow (shown in FIG. 3).

  Further, when the gear 23G rotates, the small gear 51g meshed with the gear 23G and the gear 51G fixed to the small gear 51g rotate, and the small gear (not shown) meshed with the gear 51G and fixed to the small gear. The gear 52G rotates, and the gear 22G meshing with the gear 52G rotates. The gear 22G rotates in the direction of the arrow (shown in FIG. 4) together with the third one-way clutch 43.

  The third one-way clutch 43 is interposed between the gear 22G and the shaft 22a of the feed roller 22, and freely rotates around the shaft 22a of the feed roller 22 in the direction of the arrow (shown in FIG. 4). Therefore, even if the gear 22G and the third one-way clutch 43 rotate in the arrow direction, the rotational torque in the arrow direction is transmitted from the gear 22G to the shaft 22a of the feed roller 22 via the third one-way clutch 43. The web roller 21 is fed out from the feed roller 22 following the winding of the web sheet 21 around the take-up roller 23 without being driven to rotate, and the feed roller 22 is merely driven to rotate. It is.

  Further, when the winding diameter of the web sheet 21 in the winding roller 23 is large and the winding diameter of the web sheet 21 in the feeding roller 22 is small, the winding speed and the feeding speed are increased, and the driven rotation speed of the feeding roller 22 is increased. Therefore, the rotational speed is increased between the shaft 23 a of the take-up roller 23 and the third one-way clutch 43. For this reason, when the winding speed and the feeding speed are increased, the third one-way clutch 43 is also rotated fast, and the driven rotation of the feeding roller 22 is maintained.

  For example, when the web sheet 21 is wound around the pressure roller 11, the third one-way clutch 43 is locked by the rotation of the shaft 22 a in the arrow direction to prevent the web sheet 21 from being excessively fed out from the feed roller 22. It is provided for.

  FIG. 6A is a side view schematically showing the frame configuration of the fixing device 4 and the rotation transmission unit GU. As shown in FIG. 6A, the fixing device 4 includes a first frame 61 and a second frame 62, and the rotation transmission unit GU includes a unit frame 63.

  In the first frame 61, the shaft 12a of the heating roller 12 and the shaft 13a of the heating auxiliary roller 13 are supported, and the gears 31G, 32G, 32g (shown in FIG. 3), 33G, 33g (shown in FIG. 3), 34G. , 35G are pivotally supported.

  In the second frame 62, the shaft 11a of the pressure roller 11 is supported. The second frame 62 is connected to the first frame 61 at a portion of the shaft 31a of the input gear 31, and can reciprocate around the shaft 31a of the input gear 31 as indicated by an arrow D. The reciprocating rotation angle is about 3.5 °.

  In the unit frame 63, the rotation transmission unit GU is supported. The unit frame 63 is detachably fixed to the left side wall portion of the second frame 62.

Here, normally, as shown in FIG. 6A, the second frame 62 is urged clockwise around the shaft 31a of the input gear 31 by a spring (not shown), and the second frame 62 side is urged. The shaft 11a of the pressure roller 11 approaches the shaft 12a of the heating roller 12 on the first frame 61 side, and the pressure roller 11 and the heating roller 12 are pressed against each other via the fixing belt 14 to press the fixing belt 14 and the pressure. A nip area N is formed between the rollers 11 . This state is a pressure contact state.

This pressure contact state is set when a recording sheet having a normal thickness is sandwiched in a nip area N between the fixing belt 14 and the pressure roller 11 to fix the toner image on the recording sheet.

  6B, when the second frame 62 is rotated counterclockwise around the shaft 31a of the input gear 31 against the urging force of the spring, the second frame 62 side is moved. The shaft 11a of the pressure roller 11 is further away from the shaft 12a of the heating roller 12 on the first frame 61 side, and the heating roller 12 and the fixing belt 14 are in slight contact with each other. This state is a compressed state.

  In the pressed state, not only the shaft 11a of the pressure roller 11 is further away from the shaft 12a of the heating roller 12, but also the shaft 23a of the take-up roller 23 is displaced with respect to the shaft 12a of the heating roller 12.

  This uncompressed state is set when printing a thick sealed letter or the like. In the compressed state, when a thick sealed letter or the like is sandwiched between the fixing belt 14 and the heating roller 12, an appropriate pressure and heat can be applied to the sealed letter so that the toner image on the sealed letter can be satisfactorily fixed. it can.

  The compressed state is also set when printing and fixing are not performed. In the pressure contact state, the pressure roller 11 and the heating roller 12 are pressed against each other via the fixing belt 14, and the elastic layer of the heating roller 12 is greatly dented. Therefore, if the heating roller 12 is left as it is for a long time, the heating roller 12 12 is deformed, and this causes a fixing failure. For this reason, when printing and fixing are not performed, an uncompressed state is set so that the elastic layer of the heating roller 12 is not depressed.

  As apparent from FIGS. 6A and 6B, when the pressure contact state and the pressure disengagement state are switched, the second frame 62 only rotates around the axis of the input gear 31. The interaxial distance between the gear 31 and the gear 11G of the pressure roller 11 does not change, the meshing state between the input gear 31 and the gear 11G is maintained, and the interaxial distance between the input gear 31 and the gear 32G is also maintained. There is no change, and the meshing state of the input gear 31 and the gear 32G is maintained. For this reason, the pressure roller 11 and the heating roller 12 can be rotated regardless of whether the pressure contact state or the pressure disengagement state is set, and the fixing process of the recording paper or the sealed letter is possible.

However, the positional relationship between the shaft 12a of the heating roller 12 and the shaft 23a of the take-up roller 23 changes due to switching between the pressure contact state and the pressure disengagement state, and the positional relationship between the swing cam 36 and the swing lever 37 also changes.

However, regardless of whether the pressure contact state or the pressure disengagement state is set, the swing lever 37 is urged counterclockwise around the shaft 39 by the spring 38, and the swing lever 37 is moved to the peripheral surface of the swing cam 36. Abut. For this reason, regardless of whether the pressure contact state or the pressure disengagement state is set, when the swing cam 36 rotates with the rotation of the pressure roller 11 and the heating roller 12, the swing lever 37 swings. The take-up roller 23 and the feed roller 22 rotate at a low speed, and the surface of the pressure roller 11 can be cleaned by the web sheet 21.

  Further, as shown in FIG. 6C, the unit frame 63 is detachably attached to the left side wall portion of the second frame 62, and the unit frame 63 can be replaced.

Next, operations of the swing cam 36 and the swing lever 37 will be described in detail. FIG. 7A shows the periphery of the swing cam 36 and the swing lever 37 in the press contact state in which the pressure roller 11 and the heating roller 12 are pressed against each other via the fixing belt 14 as shown in FIG. It is a side view which shows a mechanism typically.

As shown in FIG. 7A, the first one-way clutch 41 is interposed between the swing lever 37 and the shaft 39, and the swing lever 37 is biased counterclockwise around the shaft 39 by the spring 38. In contact with the circumferential surface of the swing cam 36. When the swing cam 36 rotates, the swing lever 37 swings (reciprocates) as indicated by an arrow C, and only the clockwise rotation of the swing lever 37 is transmitted to the shaft 39 through the first one-way clutch 41. The shaft 39 rotates intermittently in the clockwise direction.

  Further, the L-shaped control lever 71 is rotatably supported by a shaft 71a in the unit frame 63, and a pin 71b projects inwardly on the back side of one end of the control lever 71, and the pin 71b swings. It is inserted inside the frame portion 37a on the right side of the moving lever 37. The frame portion 37 a is hooked on the pin 71 b of the control lever 71, and the upward movement of the swing lever 37 is restricted by the pin 71 b of the control lever 71.

  A fork portion 71c is provided at the center of the control lever 71. When the tip of the plunger 72 is viewed from above, a constricted portion 72a of the plunger 72 is sandwiched inside the fork portion 71c. The plunger 72 is inserted into a hole in the center of the solenoid 73. When the solenoid 73 is in the deenergized state, the plunger 72 is urged upward by the spring 74 and protrudes from the solenoid 73. The plunger 72 is pulled into the solenoid 73 against the biasing force of the spring 74.

  When the solenoid 73 is energized and the plunger 72 is pulled inside the solenoid 73, the fork portion 71c of the control lever 71 sandwiching the constricted portion 72a of the plunger 72 is pulled down, and the control lever 71 is centered on the shaft 71a. Then, it rotates counterclockwise and the pin 71b of the control lever 71 rises. Thus, the swing lever 37 can be rotated counterclockwise until the frame portion 37a on the right side of the swing lever 37 abuts against the pin 71b, and the swing lever 37 can be swung.

At this time, the oscillating lever 37 rotates counterclockwise by the biasing force of the spring 38, and the oscillating lever 37 contacts the circumferential surface of the oscillating cam 36. When the cam gear 35G and the swing cam 36 rotate as shown in FIGS. 7A to 7D, the swing lever 37 swings up and down following the peripheral surface of the swing cam 36.

In the pressure contact state where the pressure roller 11 and the heating roller 12 is pressed to each other via the fixing belt 14 as shown in FIG. 6 (a), the pin 71b of the control lever 71 as shown in FIG. 8 (a) Yura Since the swinging angle range of the swinging lever 37 restricted by the pin 71b is widened close to the moving cam 36, the swinging angle of the swinging lever 37 is increased to 15 °.

6B, the pin 71b of the control lever 71 moves away from the swing cam 36 and is controlled by the pin 71b as shown in FIG. 8B. And the swing angle of the swing lever 37 is as small as 7.5 °.

In either the pressure contact state or the pressure disengagement state, when the cam gear 35G and the swing cam 36 rotate, the swing lever 37 swings up and down following the peripheral surface of the swing cam 36. The web sheet 21 is wound up, and the web sheet 21 is sent out from the feed roller.

9, when the solenoid 73 is de-energized and the plunger 72 protrudes from the solenoid 73, the fork portion 71c of the control lever 71 sandwiching the constricted portion 72a of the plunger 72 is pushed up, and the control lever 71 is The pin 71b of the control lever 71 moves downward by rotating clockwise around the shaft 71a. At this time, the pin 71 b is hooked on the frame portion 37 a on the right side of the swing lever 37, pulls down the right side of the swing lever 37, and rotates the swing lever 37 clockwise against the biasing force of the spring 38. As a result, the swing lever 37 is separated from the peripheral surface of the swing cam 36.

When the swing lever 37 is separated from the peripheral surface of the swing cam 36 as described above, the stopped state of the swing lever 37 is maintained even if the swing cam 36 rotates.

  For example, during the warm-up period and standby period when the image forming apparatus 1 is turned on, even if the fixing rollers 11 and 12 are rotated, the web sheet 21 does not need to be taken up or sent out. The moving lever 37 is moved away from the peripheral surface of the swing cam 36, the swing lever 37 is stopped, and the feed roller 22 and the take-up roller 23 are stopped. Further, when the winding diameter of the web sheet 21 on the winding roller 23 is increased and the winding speed to the winding roller 23 is increased, the winding amount and the feeding amount of the web sheet 21 are excessively increased. The stop period of 37 is set, the winding and feeding of the web sheet 21 are stopped, and the winding amount of the web sheet 21 is adjusted.

Thus, in the fixing device 4 of the present embodiment, the rotation of the swing cam 36 is the swing of the swing lever 37, and the swing of the swing lever 37 is intermittently rotated in one direction via the first one-way clutch 41. Therefore, a large reduction ratio can be obtained.

Further, the second frame 62 is displaced with respect to the first frame 61, the shaft 23 a of the take-up roller 23 is displaced with respect to the shaft 12 a of the heating roller 12, and the position of the swing cam 36 and the swing lever 37 is changed. even relationship is changed, since the swing lever 37 is in sliding contact with the swing cam 36, swing lever 37 swings along with the rotation of the swing cam 36, swing lever from the swing cam 36 The rotational driving force is transmitted to 37 and the winding roller 23 can be rotated.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to the example which concerns. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. It is understood.

  For example, in the above-described embodiment, the pressure roller 11 and the heating roller 12 are pressed against each other via the fixing belt (rotating member for fixing) 14, but the pressure roller (rotating member or roller for fixing) 11 and the heating roller 12 are heated. The present invention can also be applied to a configuration in which the rollers (fixing rotary members or rollers) 12 are directly pressed against each other.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Photosensitive drum 3 Transfer belt 4 Fixing apparatus 11 Pressure roller 12 Heating roller 13 Heating auxiliary roller 14 Fixing belt (rotating member for fixing)
21 Web sheet 22 Delivery roller 23 Winding roller 24 Tension roller 25 Pressure roller 36 Oscillating cam 37 Oscillating lever 38 Spring 41 First one-way clutch 42 Second one-way clutch 43 Third one-way clutch 61 First frame 62 Second frame 63 Unit frame GU Rotation transmission unit

Claims (4)

A fixing rotating member and a roller that are pressed against each other, a rotation driving unit that rotates the fixing rotating member and the roller, and a cleaning web sheet that cleans the peripheral surface of the fixing rotating member or the roller is wound or sent out. A fixing device comprising a cleaning web sheet roller,
A swing cam that is rotationally driven by the rotational drive means;
Rotation transmission means for transmitting a rotational driving force to the cleaning web sheet roller;
A one-way clutch provided on the input shaft of the rotation transmitting means;
A swing lever connected to the one-way clutch and urged to slidably contact the swing cam;
A first frame and a second frame that pivotally support the fixing rotation member and the roller, respectively.
The second frame is supported so as to be displaceable with respect to the first frame so that the pressure contact state and the pressure disengagement state of the fixing rotation member and the roller can be switched, and the swing cam and the swing lever are Provided on each of the first and second frames, regardless of the displacement position of the second frame, the swing lever of the second frame is in sliding contact with the swing cam of the first frame;
When the rocking cam is rotated by the rotation driving means, the rocking lever slidably contacting the rocking cam repeatedly rocks, and the rocking lever swings through the one-way clutch to transmit the rotation. The fixing device is transmitted to the input shaft of the means as intermittent rotation in one direction, and the intermittent rotation is transmitted to the cleaning web sheet roller via the rotation transmission means. The fixing device according to claim 1 ,
The fixing device according to claim 1, wherein a retracting means for separating and retracting the swing lever from the swing cam is provided in the second frame. The fixing device according to claim 1 , wherein:
The fixing device according to claim 1, wherein the swing lever, the one-way clutch, the rotation transmitting unit, and the cleaning web sheet roller are provided on the second frame. An image forming apparatus including a fixing device according to any one of claims 1 to 3.

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