JP2013120282A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device that prevents malfunction of a one-way clutch so that cleaning means properly operates, thereby preventing defects such as stains on an image, and an image forming apparatus.SOLUTION: A fixing device includes: a one-way clutch 91 that contacts the outer periphery of a roller shaft 42a of a pressure roller 42 to allow rotation of the pressure roller 42 in one direction and restrict rotation in the other direction; a holding member 45 that holds the one-way clutch 91; and load prevention means for preventing a pressing force by a pressure member 46 from being applied to the one-way clutch 91 (a configuration in which a shaft support part 45a of the holding member 45 receives a load, a configuration in which a bearing member 48 being a separate body from the holding member 47 receives a load, or a configuration in which the pressing force is released by a pressure lever and a solenoid 50).

Description

  The present invention relates to a fixing device and an image forming apparatus, and more particularly, to a heating member of a fixing device including a heating member having a heat source and a pressure member in pressure contact with the heating member, and from a supply roll to a take-up roll. The present invention relates to a fixing device having a cleaning unit that cleans a heating member by pressing a traveling long cleaning web with a pressing roller, and an image forming apparatus including the fixing device.

  Conventionally, as this type of fixing device, there is a web cleaning device that cleans the heating roller by pressing a long cleaning web that travels from the supply roll to the take-up roll against the heating roller of the fixing device. The heating roller is disposed upstream of the cleaning web transfer, and includes a web tension roller that applies tension to the cleaning web, and a counter roller that faces the web tension roller and sandwiches the cleaning web. The counter roller includes a cleaning web. There is known a technique in which a one-way clutch that is a rotation control member that is prohibited from rotating in the feed direction and is allowed to rotate only in the direction opposite to the cleaning web feed direction (see, for example, Patent Document 1).

  Further, in this type of fixing device, a pair of heating roller and pressure roller for heating while sandwiching the recording paper, a feeding roller for feeding a belt-shaped winding-up cleaning member (cleaning web), and the feeding roller A pressure roller that presses the cleaning member against the surface of the heating roller or the pressure roller; and a winding roller that winds the cleaning member pressed by the pressure roller. A technique is known that includes a reverse rotation prevention mechanism (one-way clutch) that prevents rotation of the pressure roller in the direction opposite to the direction (see, for example, Patent Document 2).

  However, in the fixing devices described in Patent Documents 1 and 2, the cleaning web travels in one direction by the one-way clutch, but the one-way clutch does not operate properly due to a load (radial load) received from another member. There was a problem that could cause.

  That is, when the roller provided with the one-way clutch is configured to bear the pressing load on the other rollers or the tension of the cleaning web, the radial load applied to the one-way clutch can restrict the rotation and allow the rotation in the one-way clutch. There was a problem that malfunction occurred in switching.

  The present invention has been made to solve such a problem, and a fixing device and an image forming apparatus that can prevent malfunctions of the one-way clutch and prevent malfunctions such as image smearing by properly operating the cleaning means. A device is provided.

  The fixing device according to the present invention includes a pair of pressure contact members that are in pressure contact with each other, and a heat source that heats at least one of the pair of pressure contact members, and holds the recording medium between the pressure contact members to generate heat and pressure. Fixing means for fixing the toner onto the recording medium, a long cleaning web that is unwound from the unwinding shaft and wound on the winding shaft, and one of the pair of pressure contact members by the pressure of the pressure member A pressing roller that is pressed, and cleaning means that cleans one of the pair of press contact members by bringing the cleaning web into contact with one of the pair of press contact members by the press roller, the fixing unit, and the cleaning And a housing that supports the means, contacts the outer periphery of the roller shaft of the pressure roller, allows rotation in one direction of the pressure roller, and restricts rotation in the other direction. And Ikuratchi, a holding member for holding the one-way clutch, pressure applied by the pressing member is characterized by comprising a load preventing means for preventing the applied to the one-way clutch.

  According to the present invention, it is possible to prevent problems such as image smearing by preventing the malfunction of the one-way clutch and appropriately operating the cleaning means.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a side view of a fixing device of an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view of a fixing device of an image forming apparatus according to an embodiment of the present invention. (A), (b) is sectional drawing which shows the detail of the one-way clutch of the edge part of the press roller of the fixing device of the image forming apparatus which concerns on one embodiment of this invention. FIG. 3 is a side view of a one-way clutch at an end portion of a pressing roller of the image forming apparatus according to an embodiment of the present invention. (A), (b) is a block diagram which shows an example of the holding structure of the one-way clutch of the edge part of the press roller of the image forming apparatus which concerns on one embodiment of this invention. (A), (b) is a block diagram which shows the suitable example of the holding structure of the one-way clutch of the edge part of the press roller of the image forming apparatus which concerns on one embodiment of this invention. (A)-(d) is a figure which shows each state of the one-way clutch of the edge part of the press roller of the image forming apparatus which concerns on one embodiment of this invention. It is a figure which shows the suitable example of the holding structure of the one-way clutch of the edge part of the press roller of the image forming apparatus which concerns on one embodiment of this invention. It is a figure which shows the other example of the holding structure of the one-way clutch of the edge part of the press roller of the image forming apparatus which concerns on one embodiment of this invention. It is a figure which shows the state which hold | maintained the one-way clutch of FIG. 10 to the housing. It is a figure which shows the pressurization release mechanism of the one-way clutch of the edge part of the press roller of the image forming apparatus which concerns on one embodiment of this invention.

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

  FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. The image forming apparatus is configured as a copying machine.

  As shown in FIG. 1, the image forming apparatus 1 is configured as a color printer (hereinafter referred to as “printer”) capable of forming a full color image by adopting an electrophotographic tandem method. The image forming apparatus 1 is not limited to color but may be black and white, and is not limited to the printer shown in FIG. 1, and may be a copying machine, a facsimile machine, or the like.

  With reference to FIG. 1, the basic configuration and operation of the image forming apparatus 1 configured as a printer will be described, and then the configuration and operation unique to the present embodiment will be described. The image forming apparatus 1 includes an apparatus main body 1a as an image forming unit serving as a base thereof, and a paper feed cassette 2 that is disposed below the apparatus main body 1a and stores a sheet-like recording medium 19 such as transfer paper. I have.

  In the apparatus main body 1a, an image forming unit 8 including four image forming units 8Y, 8C, 8M, and 8K as a plurality of image forming means including an image carrier, and a plurality of rollers 4, 5, 6 are provided. An intermediate transfer unit 7 having an intermediate transfer belt 3 as an intermediate transfer member constituted by a flexible endless belt wound around these rollers, and an optical writing unit that performs optical writing on each image carrier An optical writing unit 15 and a fixing device 30 for fixing the toner image on the recording medium 19 are provided.

  The image forming units 8Y, 8C, 8M, and 8K and the intermediate transfer unit 7 are detachably attached to the apparatus main body 1a.

  The space between the roller 4 and the roller 5 in the intermediate transfer belt 3 corresponds to the lower side belt running side of the intermediate transfer belt 3.

  In the intermediate transfer belt 3, a secondary transfer roller 20 serving as a secondary transfer device is disposed at a portion facing the roller 6 so as to face the conveyance path, and the intermediate transfer belt 3 is disposed at a portion facing the roller 4. A belt cleaning device 21 is provided for cleaning the surface of the belt.

  The image forming unit 8 is disposed below the intermediate transfer belt 3 by being disposed so as to face the lower running side.

  Each of the image forming units 8Y, 8C, 8M, and 8K of the image forming unit 8 includes a photosensitive drum 10 as an image carrier that is in contact with the intermediate transfer belt 3.

  Around each photosensitive drum 10, a charging device 11, a developing device 12, and a cleaning device 13 are arranged.

  Transfer rollers 14 as transfer means for performing primary transfer are provided inside the intermediate transfer belt 3 at positions where the respective photosensitive drums 10 are in contact with the intermediate transfer belt 3.

  In the present embodiment, the image forming units 8Y, 8C, 8M, and 8K are basically configured in the same structure. In FIG. 1, only the configuration of the image forming unit 8K is represented by a reference numeral. .

  The only difference between the image forming units 8Y, 8C, 8M, and 8K is the color of toner as a developer stored in each developing device 12.

  The developing devices 12 of the image forming units 8Y, 8C, 8M, and 8K store yellow (Y), cyan (C), magenta (M), and black (K) toners, respectively.

  When the toner is reduced, each developing device 12 is supplied with replenishing toner from toner replenishing bottles T1, T2, T3, and T4 disposed on the upper portion of the apparatus main body 1a.

  The optical writing unit 15 irradiates the surface of each photoconductive drum 10 with light-modulated laser light to form a latent image for each color on the surface of the photoconductive drum 10, and in the present embodiment, It is arranged below the image forming unit 8.

  The toner supply bottles T1, T2, T3, and T4, the intermediate transfer unit 7, the image forming unit 8, and the optical writing unit 15 are disposed in the apparatus main body 1a while being inclined in the same direction. Thereby, the installation area is made small compared with the case where these elements are arrange | positioned horizontally in the apparatus main body 1a.

  When the image forming operation is started, the photosensitive drums 10 of the image forming units 8Y, 8C, 8M, and 8K are rotationally driven clockwise by a driving device (not shown), and the surface of each photosensitive drum 10 is charged by the charging device 11. It is uniformly charged to a predetermined polarity.

  The surface of each charged photosensitive drum 10 is irradiated with laser light from the optical writing unit 15 to form an electrostatic latent image on each surface.

  At this time, the image information exposed to each photosensitive drum 10 is single-color image information obtained by separating a desired full-color image into color information of yellow, cyan, magenta, and black.

  The electrostatic latent image formed in this way is visualized as a toner image by the toner of each developing device 12 when passing between each photosensitive drum 10 and the developing device 12.

  Of the plurality of rollers 4, 5, 6 around which the intermediate transfer belt 3 is wound, one roller is driven to rotate counterclockwise by a driving device (not shown), whereby the intermediate transfer belt 3 is counterclockwise indicated by an arrow. Driven in the direction, the other rollers are driven to rotate.

  The yellow toner image formed by the image forming unit 8Y including the developing device 12 having yellow toner is transferred to the intermediate transfer belt 3 traveling in this way by the transfer roller 14.

  To the transferred yellow toner image, the cyan toner image formed by the image forming units 8C, 8M and 8K, and further the magenta toner image and the black toner image are successively transferred and superposed by the transfer roller 14 in this way. The transfer belt 3 carries a full-color toner image on its surface.

  Residual toner adhering to the surface of each photoconductor drum 10 after the toner image is transferred is removed from the surface of the photoconductor drum 10 by each cleaning device 13, and then the surface is subjected to a discharging operation by a discharging device (not shown). The surface potential is initialized to prepare for the next image formation.

  The recording medium 19 fed from the paper feed cassette 2 is fed into the transport path, and the paper feed timing is measured by the registration roller pair 24 disposed on the paper feed side upstream of the secondary transfer roller 20. The roller 6 and the secondary transfer roller 20 are fed to a facing portion.

  At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt 3 is applied to the secondary transfer roller 20, whereby the toner image on the surface of the intermediate transfer belt 3 is transferred to the recording medium 19. It is transcribed at the same time.

  The recording medium 19 onto which the toner image has been transferred is conveyed to the fixing device 30, and when passing through the fixing device 30, heat and pressure are applied to melt and fix the toner image.

  The recording medium 19 on which the toner image is fixed is located at the end of the conveyance path, and is conveyed to a discharge unit 23 configured by the upper part of the apparatus main body 1a, and then to a stacking unit 25 configured at the upper part of the apparatus main body 1a. Discharged.

  The toner remaining on the intermediate transfer belt 3 after the toner image is transferred to the recording medium 19 is removed by the belt cleaning device 21.

  The above description is an image forming operation when a full-color image is formed on the recording medium 19, and any one of the four image forming units 8Y, 8C, 8M, and 8K of the image forming unit 8 is used. A single color image can be formed, or a two-color or three-color image can be formed.

  When monochrome printing is performed using the printer of this embodiment, an electrostatic latent image is formed only on the photosensitive drum 10 of the image forming unit 8K, developed by the unit, and transferred to the recording medium 19. Then, the image may be fixed by the fixing device 30.

  FIG. 2 is a schematic configuration diagram showing the configuration of the fixing device 30. In the present embodiment, description will be made using a fixing roller 31 as a heating member.

  In FIG. 2, the fixing device 30 of the present embodiment includes a fixing roller 31 heated by a heater 33 and a pressure roller 32 pressed against the fixing roller 31. A fixing unit 30a that fixes the toner by sandwiching the recording paper and a cleaning unit 40 that removes the surface of the fixing roller 31 are provided.

  A separation claw 34 for preventing the recording medium 19 from being wound and a temperature sensor 35 for detecting the surface temperature of the fixing roller 31 are arranged around the fixing roller 31.

  The fixing roller 31 is rotationally driven counterclockwise by a driving device (not shown), and thereby the pressure roller 32 is driven to rotate clockwise.

  When the recording medium 19 carrying the toner image is sandwiched between the rotating fixing roller 31 and the pressure roller 32, the toner image is melted by the action of heat and pressure and fixed on the surface of the recording medium 19. Is done. An inlet guide 36 is provided at the inlet of the fixing device 30, and an outlet guide 37 is provided at the outlet of the fixing device 30. The recording medium 19 is guided by the inlet guide 36 and the outlet guide 37. .

  When such a fixing operation is performed, the toner image of the recording medium 19 is in contact with the fixing roller 31, and thus various measures are taken to reduce the toner transfer on the surface of the fixing roller 31.

  However, a slight transfer (attachment) of toner to the fixing roller 31 is unavoidable. When the amount of transferred toner increases, the toner reattaches to the surface of the recording medium 19 and soils the recording medium 19 to improve the image quality. There is a risk of deterioration.

  Therefore, the toner transferred to the fixing roller 31 is removed by the cleaning unit 40.

  2 and 3, the cleaning unit 40 includes a flexible cleaning web 44, an unwinding shaft 41 around which the cleaning web 44 is wound, and a pressing roller 42 that presses the fed cleaning web 44 against the fixing roller 31. And a take-up shaft 43 for taking up the fed cleaning web 44.

  The unwinding shaft 41, the pressing roller 42, and the winding shaft 43 are rotatably supported by a side plate such as the fixing device 30 (not shown).

  The pressing roller 42 is pressed against the fixing roller 31 by the pressure generated by the pressing member 46. In the present embodiment, the pressure member 46 is configured by a compression spring.

  The cleaning web 44 can be composed of an appropriate material such as cloth, paper, resin sheet, resin film, metal foil or the like formed into a long shape, but the cleaning web 44 is formed on the peripheral surface of the fixing roller 31. In this embodiment, the cleaning web 44 is made of a material that can be impregnated with oil, such as aramid and PET, because it is preferable that the peripheral surface is cleaned by sliding contact and oil is applied to the peripheral surface. It is comprised from the nonwoven fabric which mixes these fibers.

  When such a cleaning web 44 is in sliding contact with the peripheral surface of the fixing roller 31, the oil impregnated in the cleaning web 44 is thinly and uniformly applied to the peripheral surface of the fixing roller 31. As this oil, oil or the like that makes it difficult for the toner to transfer to the peripheral surface of the fixing roller 31, improves lubricity of the peripheral surface, and prevents wear of the peripheral surface is used.

  One end of the cleaning web 44 is fixed to the take-up shaft 43, and one end of the take-up shaft 43 is drivingly connected to a drive device (not shown) through a gear or the like.

  In the cleaning unit 40 shown in FIG. 3, the roller shafts 42 a protruding from both ends of the pressing roller 42 are rotatably supported, that is, pivotally supported by the one-way clutch 91 held by the holding member 45, and the pressing roller 42. Is allowed to rotate in only one direction.

  As described above, when the roller shaft 42a is rotatably supported by the one-way clutch 91 and is allowed to rotate in one direction, the function of the bearing and the function of the one-way clutch are the same configuration (integrated configuration). Therefore, it can be made very compact, and has the advantages of space saving and low cost.

  4A and 4B are cross-sectional views showing an example of the internal structure of the one-way clutch 91. FIG. FIG. 5 is a side view of the one-way clutch 91 when the roller shaft 42a is not inserted.

  As shown in FIGS. 4A, 4B, and 5, the one-way clutch 91 is formed on an outer ring 91a that is rotatably fitted on the outer periphery of the roller shaft 42a, and an inner peripheral portion of the outer ring 91a. It comprises a roller 91b accommodated in the recessed portion and a spring 91c.

  FIG. 4A shows a case where the roller shaft 42a tries to rotate in the arrow R3 direction. When the roller shaft 42a tries to rotate in the R4 direction, the roller 91b moves to the engagement position of the recess formed in the inner peripheral portion of the outer ring 91a by the action of the spring 91c, and the outer peripheral surface of the roller shaft 42a and the inner peripheral surface of the recess The roller shaft 42a is locked (rotation is restricted) by the wedge action with the surface.

  FIG. 4B shows a case where the outer ring 91a is stationary and the roller shaft 42a rotates in the arrow R4 direction. When the roller shaft 42a rotates in the R4 direction, the roller 91b moves away from the inner peripheral surface of the outer ring 91a, and the roller shaft 42a idles with respect to the outer ring 91a (rotation is allowed).

  Each operation state of the one-way clutch 91 is as follows.

  State 1: When the winding shaft 43 is rotating (the cleaning web 44 is in the winding state: arrow R1): The one-way clutch 91 is idling.

  State 2: Take-up shaft 43 stopped, fixing roller 31 stopped: One-way clutch 91 maintains neutral = previous state.

  State 3: Winding shaft 43 is stopped, fixing roller 31 is rotated (arrow R2): One-way clutch 91 is locked.

  The one-way clutch 91 maintains the state in which the operation has been finished last (locked state / idle state = non-locked state).

  Here, in the one-way clutch 91 configured as shown in FIG. 4, leaving it in the unlocked state causes a malfunction. That is, the one-way clutch 91 does not work well when it is left for a long time under pressure applied by the pressure member 46 in an unlocked state, or when it is left in a low temperature environment, and the roller 91b has a wedge-shaped lock. It may cause a malfunction that cannot be moved to the position.

  As a cause of this, the grease enclosed in the one-way clutch 91 hinders the movement of the roller 91b due to an increase in viscosity at low temperatures, or the roller 91b left pressed for a long time while being in the unlocked position. There is a case where the return is poor and it is not possible to move to the lock position.

  This malfunction does not occur when the roller 91b is left pressed for a long time while being in the locked position. In addition, even if it is difficult to reduce the probability of occurrence of this malfunction to zero, it is possible to reduce the probability of occurrence by reducing the load on the one-way clutch 91, as will be described later.

  Here, as a holding structure of the one-way clutch 91, as shown in FIGS. 6A and 6B, the one-way clutch 91 is press-fitted or adhered to the holding member 45 to be held by the holding member 45. On the other hand, it can be considered that the one-way clutch 91 is fixed. 6A and 6B, the holding member 45 holds the one-way clutch 91, and the roller shaft 42a of the pressing roller 42 is mainly supported by the one-way clutch 91.

  In this case, when the holding structure of the one-way clutch 91 is configured as shown in FIGS. 6A and 6B, the pressure applied by the pressing member 46 to the pressing roller 42 is such that the one-way clutch 91 has a radial load. Therefore, when the one-way clutch 91 is left in a non-locked state and left for a long time in such a situation, the roller 91b cannot move to the wedge-shaped lock position and the wedge action is good. The one-way clutch 91 may not operate properly.

  Therefore, in order to avoid malfunction of the one-way clutch 91, in this embodiment, the holding structure of the one-way clutch 91 is configured as shown in FIG.

  In FIG. 7A, a radial gap is provided between the holding member 45 and the one-way clutch 91, and the one-way clutch 91 is not fixed to the holding member 45, and is within the gap. It can be displaced in the radial direction.

  The one-way clutch 91 may be fixed to the holding member 45 with respect to the thrust direction (axial direction) position or may be displaceable with a gap. The position is maintained so as not to drop off from the holding member 45 by (prevention).

  The holding member 45 is slidably positioned in the cutout window 38 a of the side plate 38, and presses the pressing roller 42 against the fixing roller 31 by the pressing force of the pressing member 46.

  As shown in FIG. 7B, a shaft support 45a that rotatably supports the roller shaft 42a of the pressing roller 42 is held at the outer end of the holding member 45 (the right end of FIG. 7B). It is formed integrally with the member 45. That is, the shaft support portion 45a of the holding member 45 functions as a sliding bearing.

  On the other hand, the one-way clutch 91 is held displaceably with a gap in the radial direction with respect to the holding member 45. For this reason, the pressure applied by the pressure member 46 to the pressing roller 42 is received by the shaft support portion 45a of the holding member 45 before being received by the one-way clutch 91, and the one-way clutch 91 does not receive a load directly. The gap between the one-way clutch 91 and the holding member 45 needs to be large enough to allow for the movable range of the roller 91b (see FIG. 8D).

  By adopting such a configuration, the one-way clutch 91 does not directly receive the pressing force of the pressing roller 42, so that the one-way clutch 91 may be left for a long time while receiving the pressing force in an unlocked state. Therefore, the roller 91b cannot move to the wedge-shaped lock position, and the wedge action does not work well, so that malfunction does not occur.

  The locked state of the one-way clutch 91 will be described with reference to FIG. 8A to 8D, a broken-line circle drawn outside the roller shaft 42a of the pressing roller 42 is an inner peripheral surface of the outer ring 91a of the one-way clutch 91, and the inner peripheral surface of the outer ring 91a. The gap between the roller shaft 42a and the roller shaft 42a is a movable range of the roller shaft 42a.

  As shown in FIG. 8A, in a state where no load is applied to the one-way clutch 91 (non-rotating state), the roller 91b is in contact with the roller shaft 42a of the pressing roller 42 due to the load of the spring 91c. The two rollers 91b are in contact with the roller shaft 42a of the pressing roller 42 evenly.

  As shown in FIG. 8B, in the rotation restricted state where the one-way clutch 91 is locked, the driving force is applied to the pressing roller 42 in the direction indicated by the arrow R3. In this state, the roller shaft 42a of the pressing roller 42 is locked.

  As shown in FIG. 8C, when the one-way clutch 91 is not locked, the pressing roller 42 is applied with a driving force in the direction indicated by the arrow R4, and the roller 91b is a roller of the pressing roller 42. The driving force from the shaft 42a receives a force in the direction of the arrow opposite to the spring 91c. As a result, the roller shaft 42a of the pressing roller 42 is idled out of the wedge shape.

  As shown in FIG. 8D, when the load is applied to the one-way clutch 91 (non-rotating state), the roller 91b is not locked, and pressure is applied to the roller shaft 42a of the pressing roller 42. The roller shaft 42a of the pressing roller 42 moves within the load direction and the movable range, and is pressed against one side as shown in the figure. As a result, the roller 91b is retracted against the force of the spring 91c. That is, the roller 91b moves from the position drawn by the alternate long and short dash line to the position drawn by the solid line.

  When left in a state as shown in FIG. 8D for a long time, the problem described in FIGS. 6A and 6B may occur. In this state, there is a possibility that the wedge action does not work well when left in a non-locked state under pressure for a long time or left in a low temperature environment, and the roller 91b has a wedge shape. May not move to the lock position.

  In the present embodiment, as described with reference to FIG. 7, such a problem is avoided by preventing a radial load from being applied to the one-way clutch 91.

  FIG. 9 shows a dropout prevention structure that prevents the one-way clutch 91 from falling off the holding member 45.

  As shown in FIG. 9, the holding member 45 is held in a slidable state in the pressing direction by a side plate 38 constituting a housing that supports the cleaning unit 40. For example, as shown in the drawing, the holding member 45 is positioned by fitting the end face of the cutout window 38a of the side plate 38 into a groove formed in the holding member 45 in a state of being fitted with a gap.

  On the other hand, on the base part of the roller shaft 42a of the pressing roller 42 (the end surface of the pressing roller 42), an annular protrusion-shaped drop prevention convex part 42b protruding toward the holding member 45 is provided. The one-way clutch 91 does not drop from the holding member 45 toward the pressing roller 42 even when the one-way clutch 91 is not fixed to the holding member 45 by the drop-off preventing convex portion 42b serving as a stopper. By setting the distance between the two side plates 38 and the length of the pressing roller 42 to optimum values, it is possible to prevent the pressing roller 42 from falling off the holding member 45.

  FIG. 10 shows another example of the holding structure for the one-way clutch 91. As shown in FIG. 10, the holding member 47 that holds the one-way clutch 91 and the bearing member 48 that rotatably supports the roller shaft 42 a of the pressing roller 42 may be configured separately.

  10, the holding member 47 has a function of only holding the one-way clutch 91, like the holding member 45 shown in FIG. 6, and the bearing member 48 receives the load from the roller shaft 42a. Yes.

  In this case, the number of parts increases due to the separate configuration of the holding member 47 and the bearing member 48. However, since the pressing force does not act on the holding member 47, the function of preventing the load on the one-way clutch 91 is ensured. .

  A bearing member 48 and a holding member 47 holding the one-way clutch 91 are attached to the roller shaft 42a of the pressing roller 42 adjacent to each other in the axial direction. The one-way clutch 91 and the holding member 47 may be fixed and held as usual by press-fitting, bonding, or the like.

  The bearing member 48 slides and holds the roller shaft 42a of the pressing roller 42 and is slidably positioned in the notch window 38a of the side plate 38 so as to transmit the pressure applied by the pressing member 46 to the pressing roller 42. It has become.

  On the other hand, the holding member 47 is fixed in position by inserting the holding one-way clutch 91 into the roller shaft 42 a of the pressing roller 42. At this time, a means for restricting the rotation of the one-way clutch 91 with respect to the rotation of the pressing roller 42 is required.

  Therefore, as shown in FIGS. 10 and 11, a protrusion-shaped rotation preventing portion 47 a is formed on the holding member 47, and the rotation preventing portion 47 a is engaged (engaged) with the cutout window 38 a of the side plate 38. The rotation of the holding member 47 is restricted.

  FIG. 12 shows another configuration for avoiding the load applied to the one-way clutch 91 when left for a long time. As described above, the one-way clutch 91 may fail when left for a long time in a loaded state. However, even if the one-way clutch 91 is loaded, If it takes a short time, there will be no problems.

  Therefore, the pressurizing force release mechanism shown in FIG. 12 is effective as a configuration that avoids applying a load to the one-way clutch 91 when left for a long time.

  In FIG. 12, the pressurizing lever 49 and the solenoid 50 constitute a pressurizing force release mechanism. In addition, in FIG. 12, as a member for holding the one-way clutch 91, the integrally configured holding member 45 described with reference to FIGS. 7 and 9, or the separate holding member 47 described with reference to FIGS. Either can be used.

  The pressure lever 49 is configured to transmit a pressing force to the holding member 45 or the holding member 47 via the pressure member 46. One end of the pressurizing lever 49 is rotatably supported and the other end is connected to the solenoid 50, and the operation of the solenoid 50 can generate and release the applied pressure to the holding member 45 or the holding member 47. You can choose.

  That is, by driving the solenoid 50 and moving the pressure lever 49 to the pressure position indicated by the solid line, the pressure member 46 is compressed and pressure is generated (pressure generation state). Is moved to the pressure release position indicated by the broken line, so that the applied pressure is released (the applied pressure release state).

  Here, when the apparatus is operating (printing), the pressure is generated, and at other times (when the apparatus is on standby, in the apparatus energy saving mode, when the power is turned off), the pressure is released, so that the one-way clutch 91 is It is possible to avoid leaving for a long time in a state where a load is applied, and the one-way clutch 91 can be prevented from malfunctioning.

  In the present embodiment, the configuration using the pressurizing lever 49 and the solenoid 50 is exemplified as the pressurizing force release mechanism. However, the present invention is not limited to this configuration. The same effect can be obtained even if a configuration using the above is employed.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited only to this embodiment. For example, the fixing device 30 of the present embodiment is configured as a so-called roller fixing device including a fixing roller 31 and a pressure roller 32, but other types of fixing devices, for example, the pressure roller 32, Instead, a so-called belt fixing device using a fixing belt may be used. Further, the fixing member cleaned by the cleaning device is not limited to the fixing roller 31 but may be a pressure roller 32, a fixing belt, or the like.

  As described above, the fixing device 30 according to the present embodiment includes the fixing roller 31 and the pressure roller 32 that are in pressure contact with each other, and the heater 33 that heats the fixing roller 31. The fixing roller 31 and the pressure roller 32, a fixing unit 30a that sandwiches the recording medium and fixes the toner to the recording medium by heat and pressure, a long cleaning web 44 that is unwound from the unwinding shaft 41 and wound around the winding shaft 43, A pressing roller 42 that is pressed against the fixing roller 31 by the pressure of the pressure member 46, and a cleaning unit 40 that cleans the fixing roller 31 by bringing the cleaning web 44 into contact with the fixing roller 31 by the pressing roller, and a fixing unit 30a. And a side plate 38 that supports the cleaning unit 40, and comes into contact with the outer periphery of the roller shaft 42 a of the pressing roller 42 to press the pressing roller 4. One-way clutch 91 that allows rotation in one direction and restricts rotation in the other direction, holding member 45 that holds one-way clutch 91, and pressure applied by pressure member 46 are prevented from being applied to one-way clutch 91. And a load preventing means (a shaft support portion 45a of the holding member 45 or a bearing member 48 separate from the holding member 47, or a pressure lever and a solenoid 50).

  With this configuration, since the load preventing means prevents the pressure applied by the pressure member 46 from being applied to the one-way clutch 91, the one-way clutch 91 is allowed to rotate in one direction and the rotation is restricted in the other direction. Is performed normally. Accordingly, it is possible to prevent problems such as image smearing by preventing the one-way clutch 91 from malfunctioning and causing the cleaning unit 40 to operate properly.

  Further, in the fixing device 30 according to the present embodiment, the load preventing means is formed integrally with the holding member 45 at the outer end in the axial direction of the holding member 45, and rotatably supports the roller shaft 42a of the pressing roller 42. And a shaft support 45a that receives pressure applied by the pressure member 46.

  With this configuration, since the shaft support portion 45a of the holding member 45 that holds the one-way clutch 91 receives pressure applied by the pressing member 46, the one-way clutch 91 does not receive a load, so the number of parts does not increase, and the cost is reduced. It is possible to prevent problems such as image smearing by saving space and preventing the one-way clutch 91 from malfunctioning and operating the cleaning unit 40 appropriately.

  Further, the fixing device 30 according to the present embodiment provides a radial gap between the holding member 45 and the one-way clutch 91, and the holding member 45 holds the one-way clutch 91 so that the one-way clutch 91 can be displaced in the radial direction within the gap. It is characterized by that.

  With this configuration, the holding member 45 holds the one-way clutch 91 so as to be displaceable in the radial direction within the gap, so that the one-way clutch 91 is reliably pressurized without being loaded with the shaft support portion 45a of the holding member 45. The pressure applied by the member 46 can be received.

  Further, the fixing device 30 according to the present embodiment is formed at the base portion of the roller shaft 42a of the pressing roller 42 so as to protrude toward the holding member 45, and the one-way clutch 91 is dropped to the pressing roller 42 side. It is characterized in that a drop-off preventing convex portion 42b is provided.

  With this configuration, the one-way clutch 91 is prevented from dropping to the pressing roller 42 side by the drop-off preventing convex portion 42b, so that the number of parts is not increased, and the operation of the one-way clutch 91 is reduced at low cost and space saving. By preventing the cleaning unit 40 from operating properly, problems such as image smearing can be prevented.

  Further, in the fixing device 30 according to the present embodiment, the load preventing unit is configured separately from the holding member 47, and supports the roller shaft 42 a of the pressing roller 42 so as to be rotatable, and the pressing force by the pressing member 46. It is characterized by comprising a bearing member 48 for receiving.

  With this configuration, since the holding member 47 and the bearing member 48 are configured separately, the holding member 47 holds the one-way clutch 91 and the bearing member 48 rotatably supports the roller shaft 42a of the pressing roller 42. Therefore, even when the one-way clutch 91 is likely to malfunction, the one-way clutch 91 is reliably prevented from malfunctioning and the cleaning unit 40 is operated properly to prevent the image from becoming dirty. Can be prevented.

  Further, the fixing device 30 according to the present embodiment is characterized in that the holding member 47 includes a rotation preventing portion 47a that engages with the side plate 38 so as to prevent the holding member 47 from rotating.

  With this configuration, even if the holding member 47 and the bearing member 48 are configured separately, the rotation preventing portion 47a of the holding member 47 is engaged with the housing, thereby preventing the holding member 47 itself from rotating. Therefore, even under a situation in which malfunction of the one-way clutch 91 is likely to occur, malfunction such as image smearing can be prevented by reliably preventing malfunction of the one-way clutch 91 and operating the cleaning unit 40 properly.

  In the fixing device 30 according to the present embodiment, the load preventing means includes a pressure lever 49 and a solenoid 50 as a pressure release mechanism that releases pressure applied by the pressure member 46 while the apparatus is stopped. And

  With this configuration, the pressure lever 49 and the solenoid 50 release the pressure applied by the pressure member 46 while the apparatus is stopped, thereby preventing the pressure applied by the pressure member 46 from being applied to the one-way clutch 91. Even in a situation where the operation failure 91 is likely to occur, it is possible to prevent the operation failure of the one-way clutch 91 and to properly operate the cleaning web to prevent problems such as image smearing.

  In addition, the image forming apparatus 1 according to the present embodiment includes the fixing device 30 described above.

  With this configuration, in the image forming apparatus 1, it is possible to prevent malfunctions of the one-way clutch 91 and prevent malfunctions such as image smearing by properly operating the cleaning unit 40.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1a Apparatus main body 30 Fixing apparatus 30a Fixing part 31 Fixing roller (pressure contact member)
31a Fixing part (fixing means)
32 Pressure roller (pressure contact member)
33 Heater (heat source)
38 Side plate (frame)
38a Notch window 40 Cleaning part (cleaning means)
41 Unwinding shaft 42 Pressing roller 42a Roller shaft 42b Drop-off preventing convex portion 43 Winding shaft 44 Cleaning web 45, 47 Holding member 45a Shaft supporting portion (load preventing means)
46 Pressure member 48 Bearing member (load prevention means)
49 Pressure lever (load prevention means, pressure release mechanism)
50 Solenoid (load prevention means, pressure release mechanism)
91 One-way clutch 91a Outer ring 91b Roller 91c Spring

JP 2009-63690 A JP 2008-15444 A

Claims (8)

A pair of pressure contact members that are in pressure contact with each other; and a heat source that heats at least one of the pair of pressure contact members. The recording medium is sandwiched between the pressure contact members and the toner is fixed to the recording medium by heat and pressure. Fixing means;
A long cleaning web that is unwound from the unwinding shaft and wound on the winding shaft, and a pressing roller that is pressed against one of the pair of pressure contact members by the pressure of the pressure member, and the cleaning Cleaning means for cleaning one of the pair of press contact members by bringing a web into contact with one of the pair of press contact members by the pressing roller;
A fixing device including a housing supporting the fixing unit and the cleaning unit;
A one-way clutch that contacts the outer periphery of the roller shaft of the pressing roller and allows rotation in one direction of the pressing roller and restricts rotation in the other direction;
A holding member for holding the one-way clutch;
And a load preventing means for preventing the pressure applied by the pressure member from being applied to the one-way clutch. The load preventing means is
The support member is formed integrally with the holding member at an axially outer end portion of the holding member, and includes a shaft support portion that rotatably supports a roller shaft of the pressing roller and receives pressure applied by the pressure member. The fixing device according to claim 1.   3. The fixing according to claim 2, wherein a radial gap is provided between the holding member and the one-way clutch, and the holding member holds the one-way clutch so as to be displaceable in the radial direction within the gap. apparatus.   The base of the roller shaft of the pressure roller is formed with a shape that protrudes toward the holding member, and a drop-off prevention convex portion that prevents the one-way clutch from falling toward the pressure roller is provided. The fixing device according to claim 2 or 3. The load preventing means is
2. The fixing device according to claim 1, wherein the fixing device includes a bearing member configured separately from the holding member and configured to rotatably support a roller shaft of the pressing roller and receive pressure applied by the pressing member. .   The fixing device according to claim 5, wherein the holding member includes an anti-rotation portion that engages with the housing to prevent the holding member from rotating. The load preventing means is
The fixing device according to claim 1, further comprising a pressure release mechanism that releases pressure applied by the pressure member while the apparatus is stopped.   An image forming apparatus comprising the fixing device according to claim 1.

Images