JP6358202B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  2. Description of the Related Art An electrophotographic image forming apparatus such as a copying machine, a printer, a fax machine, and a multifunction machine includes a fixing device that fixes a toner image on a sheet. Some fixing devices include a fixing belt that is heated by a heat source and is in pressure contact with a pressure rotator so as to be driven to rotate.

  In a fixing device including such a fixing belt, a halogen heater may be provided as a heat source in the hollow portion of the fixing belt in order to improve energy saving. When the halogen heater is provided as described above, it is necessary to always rotate the fixing belt while the halogen heater is turned on in order to prevent local heating of the fixing belt. In order to prevent the rotation of the fixing belt from stopping while the halogen heater is lit, the fixing device is provided with a mechanism for monitoring the operation of the fixing belt not only during warm-up but also during lighting of the halogen heater.

  In order to monitor the operation of the fixing belt, Patent Document 1 discloses that a rotation detection pattern having light reflectivity different from the surroundings is formed on the outer peripheral surface of the fixing belt, and this rotation detection pattern is detected by a detection device. A fixing device configured to monitor the rotation of the fixing belt is described. Japanese Patent Application Laid-Open No. 2005-228561 describes a fixing device that is provided with a roller that rotates following a fixing belt and monitors the rotation of the fixing belt by detecting the rotation speed of the roller.

  Further, in Patent Document 3, a gear is formed on the outer peripheral surface of the end portion of the fixing belt, a cap member having a gear meshing with the gear is fitted to the end portion of the fixing belt, and the rotation of the fixing belt is controlled by the gear. The fixing device is configured to be transmitted to the cap member through the fixing device. In Patent Document 4, a gear is formed on the inner peripheral surface of the end portion of the fixing belt, and a cap member having a gear meshing with the gear is fitted into the opening of the end portion of the fixing belt. The fixing device is configured to rotate the fixing belt via the fixing belt.

JP-A-2005-173180 JP 2000-200006 A Japanese Patent Laying-Open No. 2015-22047 JP 2005-249958 A

  However, in the fixing device described in Patent Document 1, it is necessary to form holes or markings on the outer peripheral surface of the fixing belt as a rotation detection pattern. Detection failure or fixing belts may be detected due to damage from the holes or peeling of the markings. There is a risk of damage. Further, in the fixing device described in Patent Document 2, the contact between the fixing belt and the roller becomes unstable, and the roller may not be driven and rotated by the fixing belt.

  Furthermore, since the fixing belt has a structure with low cylindrical rigidity and is difficult to maintain a perfect circular shape, in the fixing device described in Patent Document 3, there is a possibility that slip occurs between the fixing belt and the cap member. Note that when the cap member is fitted in the opening of the fixing belt as in Patent Document 4, slipping is eliminated, but only the end of the fixing belt is supported by the cap member, so that the boundary between the ends There is a possibility that stress concentration occurs due to a shape change in the portion, and the fixing belt is damaged. Further, as in Patent Document 3 and Patent Document 4, when a gear is formed on the fixing belt, a special process for adhering the elastic gear to the fixing belt is required, resulting in an increase in cost.

  It is also conceivable to monitor the rotation of the fixing belt by detecting the rotation of the pressure roller that is driven to rotate by the fixing belt. However, a slip may occur between the pressure roller and the fixing belt. There is a problem that the rotation of the can not be accurately monitored.

  In view of the above circumstances, an object of the present invention is to provide a fixing device and an image forming apparatus capable of accurately monitoring the state of the fixing belt.

  In order to solve the above-described problems, a fixing device of the present invention is provided rotatably about a rotation shaft, and is driven by a fixing belt heated by a heat source and rotated in pressure contact with the fixing belt. A pressure rotating member that rotates, an end surface receiving member that faces the end surface on the outer side in the rotation axis direction of the end surface of the fixing belt, is slidable in the rotation axis direction, and is rotatable about the rotation axis; An urging member that urges the end surface receiving member in the direction of the end surface of the fixing belt; and a detection unit that detects rotation of the end surface receiving member. The end surface receiving member is urged by the urging member. The rotation of the fixing belt is performed by detecting the rotation of the end surface receiving member by the detecting means by being pressed against the end surface of the fixing belt and rotating following the fixing belt. Characterized in that it monitors.

  By adopting such a configuration, the rotation of the fixing belt can be accurately and stably transmitted to the end face receiving member. Therefore, the state of the fixing belt can be monitored by detecting the rotation of the end face receiving member. In addition, since it is not necessary to mark the fixing belt or form an opening, it is difficult to cause damage to the fixing belt or erroneous detection of the detection means, and it is not necessary to perform special processing on the fixing belt. Cost increase can be suppressed.

  In the fixing device according to the present invention, the fixing device may further include a regulating member provided so as to be in contact with the end face contact member at a position spaced apart from the normal position of the end face of the fixing belt by a predetermined length inward in the rotation axis direction. Also good.

  When an abnormality such as breakage or buckling occurs, the end surface of the fixing belt moves inward. Thus, by adopting such a configuration, when the end surface of the fixing belt is separated from the normal position by a predetermined amount or more, the end surface receiving member comes into contact with the regulating member and is separated from the end surface of the fixing belt, so that the rotation is stopped. By detecting the stop of the rotation of the end face receiving member, it is possible to detect that the end face of the fixing belt has moved inward from a predetermined amount, that is, an abnormality of the fixing belt, and promptly cope with it.

  In the fixing device of the present invention, an elastic member is interposed between the end surface of the fixing belt and the end surface receiving member, and the elastic member faces the end surface of the fixing belt of the end surface receiving member. It may be characterized by being formed of a material having a higher friction coefficient.

  By adopting such a configuration, the frictional force between the end face of the fixing belt and the end face receiving member is increased, so that the end face receiving member is easily driven and rotated by the fixing belt.

  In the fixing device of the present invention, the end face receiving member may be formed of a heat resistant resin or metal.

  By adopting such a configuration, the end face receiving member can be smoothly rotated by being driven by the fixing belt.

  In the fixing device of the present invention, the detection unit may be a transmissive optical sensor that detects light transmitted through the end surface receiving member.

  By adopting such a configuration, the rotation of the end face receiving member can be reliably detected with a simple mechanism.

  In the fixing device of the present invention, the detecting means may be a reflective photosensor that detects light reflected by the end face receiving member.

  By adopting such a configuration, the rotation of the end face receiving member can be reliably detected with a simple mechanism.

  The image forming apparatus of the present invention includes any one of the fixing devices described above.

  According to the present invention, since the state of the fixing belt is monitored by detecting the rotation of the end face receiving member that is in pressure contact with the end surface of the fixing belt, the state of the fixing belt can be accurately monitored. Local heating can be prevented.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. 1 is a front sectional view of a fixing device according to an embodiment of the present invention. FIG. 3 is a side sectional view showing an end face receiving member in contact with the fixing belt in the fixing device according to the embodiment of the present invention. FIG. 4 is a side sectional view showing an end face receiving member that is separated from the fixing belt in the fixing device according to the embodiment of the present disclosure.

  Hereinafter, an image forming apparatus and a fixing device of the present invention will be described with reference to the drawings.

  First, the overall configuration of the printer 1 (image forming apparatus) will be described with reference to FIG. FIG. 1 is a diagram schematically showing an outline of the printer 1. In the following, the front side of the paper in FIG. 1 is the front side (front side) of the printer, and the left and right directions will be described with reference to the direction viewed from the front of the printer.

  The printer 1 includes a box-shaped printer main body 2. A paper feed cassette 3 for containing paper (recording medium) is housed in the lower part of the printer main body 2, and a paper feed unit 4 is provided at the upper left of the paper feed cassette 3. A paper discharge tray 5 is provided on the upper surface of the printer main body 2. An upper cover 6 is attached to the left side of the paper discharge tray 5 so as to be openable and closable, and a toner container 7 is stored below the upper cover 6.

  An exposure unit 9 composed of a laser scanning unit (LSU) is disposed below the discharge tray 5 above the printer main body 2, and an image forming unit 10 is provided below the exposure unit 9. Yes. A photosensitive drum 11 is rotatably provided in the image forming unit 10, and a transfer nip 14 is provided around the photosensitive drum 11 between the charger 12, the developing device 13, and the photosensitive drum 11. And a cleaning device 16 are arranged along the direction of rotation of the photosensitive drum 11 (see arrow X in FIG. 1). A fixing device 18 is provided on the right side of the image forming unit 10, and a paper discharge unit 19 facing the paper discharge tray 5 is provided above the fixing device 18.

  The printer main body 2 is provided with a paper conveyance path 20 from the paper supply unit 4 through the transfer nip 14 and the fixing device 18 to the paper discharge unit 19. A reverse path 21 for double-sided printing is formed below the transport path 20.

  Next, an image forming operation of the printer 1 having such a configuration will be described. First, after the surface of the photosensitive drum 11 is charged by the charger 12, exposure corresponding to the image data is performed on the photosensitive drum 11 by laser light from the exposure device 9 (see a two-dot chain line in FIG. 1). As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 11. Next, the electrostatic latent image is developed into a toner image by the developing device 13 with toner.

  On the other hand, the sheet taken out from the sheet feeding cassette 3 by the sheet feeding unit 4 is conveyed to the transfer nip 14 in synchronization with the above-described image forming operation, and the toner image on the photosensitive drum 11 is transferred to the sheet at the transfer nip 14. Is transcribed. The sheet on which the toner image has been transferred is conveyed downstream in the conveyance path 20 and enters the fixing device 18 where the toner image is fixed on the sheet. The paper on which the toner image is fixed is discharged from the paper discharge unit 19 to the paper discharge tray 5. The toner remaining on the photosensitive drum 11 is collected by the cleaning device 16.

  Next, the fixing device 18 will be described with reference to FIGS. 2 is a front sectional view showing the fixing device, FIGS. 3 and 4 are side sectional views showing one end of the fixing device, and FIG. 3 shows a state in which the end face receiving member is in contact with the end surface of the fixing belt. FIG. 4 shows a state in which the end face receiving member is separated from the end face of the fixing belt.

  The fixing device 18 includes a rotatable fixing belt 31, a halogen heater 32 that is a heat source for heating the fixing belt 31, a pressure roller 33 that is a pressure rotating member that rotates the fixing belt 31, and the fixing belt 31. A pressure member 34 that is in pressure contact with the pressure roller 33, an end surface receiving member 35 that faces the both end surfaces of the fixing belt 31, and an urging member that urges the end surface receiving member 35 toward the end surface of the fixing belt 31. It has a coil spring 36 and a transmission type optical sensor 37 as a detecting means for detecting the rotation of each of the end face receiving members 35, and is supported between side plates 38 arranged facing each other in the front-rear direction. .

  The fixing belt 31 has a substantially cylindrical shape that is long in the front-rear direction, and is formed of a flexible material. The fixing belt 31 includes, for example, a base material layer, an elastic layer provided around the base material layer, and a release layer that covers the elastic layer. The base material layer is made of, for example, a metal such as SUS or a resin such as PI (polyimide), the elastic layer is made of, for example, silicone rubber, and the release layer is made of, for example, PFA (tetrafluoroethylene-perfluoroalkyl). Vinyl ether copolymer) tube. In each figure, each layer (base material layer, elastic layer, release layer) of the fixing belt 31 is displayed without being particularly distinguished.

  The fixing belt 31 is supported rotatably about a pair of belt end holding members 41 as rotation axes. Each belt end holding member 41 has a 3/4 arc-shaped cylindrical shape whose cross-sectional shape is convex upward, and protrudes in a direction facing each side plate 38. Both end portions of the fixing belt 31 rotate while sliding along the outer peripheral surface of each belt end portion holding member 41.

  The halogen heater 32 is disposed above the hollow portion of the fixing belt 31 so as to extend in the longitudinal direction of the fixing belt 31, and both end portions are supported by the side plates 38 through the insides of the belt end portion holding members 41. ing.

  The pressure roller 33 includes a columnar core material, an elastic layer provided around the core material, and a release layer that covers the elastic layer. The core material is made of, for example, a metal such as iron, the elastic layer is made of, for example, silicone rubber, and the release layer is made of, for example, a PFA tube. In each figure, each layer (core material, elastic layer, release layer) of the pressure roller 33 is displayed without being particularly distinguished. The pressure roller 33 is disposed on the lower side of the fixing belt 31 and is supported so as to be rotatable in the clockwise direction in FIG. 2 about a rotation shaft 33a extending in the front-rear direction.

  The pressing member 34 is a substantially rectangular parallelepiped member that is long in the front-rear direction, the lower surface is curved downward toward the downstream side in the rotation direction of the fixing belt 31, and the angle between the lower surface and both side surfaces is curved in an arc shape. doing. The pressing member 34 is supported by the support member 34 a and is disposed below the hollow portion of the fixing belt 31. The support member 34a is supported on each side plate 38 so that the lower surface of the pressing member 34 presses the fixing belt 31 downward.

  When the fixing belt 31 is pressed downward by the pressing member 34, the fixing belt 31 is pressed against the pressure roller 33. When the fixing belt 31 is brought into pressure contact with the pressure roller 33 in this way and the pressure roller 33 is rotated, the fixing belt 31 is driven by the pressure roller 33 as shown in FIG. Rotate around both belt end holding members 41 in the direction opposite to the direction of rotation of the belt.

  As shown in FIGS. 3 and 4, the end face receiving member 35 is a disk-shaped member having an outer diameter larger than the outer diameter of the fixing belt 31, and is arranged so as to face both end faces of the fixing belt 31. Supported by the belt end holding member 41, the belt end holding member 41 can slide in the axial direction, and can rotate around each belt end holding member 41. The end face receiving member 35 is formed of a metal or a heat resistant resin, and for example, a metal such as SECC or SUS, PPS, PEEK, PAI, PI, a fluororesin, or the like can be used.

  The end face receiving member 35 is provided with an elastic member 51 having an outer diameter larger than the outer diameter of the fixing belt 31 on the surface facing the fixing belt 31. The elastic member 51 is made of a material having a higher friction coefficient than the friction coefficient of the surface of the end face receiving member 35 facing the fixing belt 31. As such a material, for example, silicone rubber can be used. Further, openings 35a, which are detection patterns of the transmissive optical sensor 37, are provided on the outer peripheral portion of the end face receiving member 35 at predetermined intervals along the circumferential direction. In place of the opening 35a, a notch cut out from the outer peripheral edge of the end face receiving member 35 may be formed. Furthermore, instead of the opening 35a, a member having a light reflectivity different from the light transmissivity of the end face receiving member 35, such as a transparent plate, may be embedded.

  Each end surface receiving member 35 is urged toward the end surface of the fixing belt 31 by a coil spring 36 via a movable base 54. The movable base 54 is supported by the belt end holding member 41 so as to be slidable in the rotation axis direction between the end face receiving member 35 and the side plate 38.

  A plurality of (for example, three) spring holding members 56 are attached to each side plate 38 from the outside to the inside at predetermined intervals along the outer periphery of the belt end holding member 41. The spring holding member 56 has a large-diameter portion 56 a supported on the outer surface of the side plate 38 and a small-diameter portion 56 b that penetrates the side plate 38 and protrudes inward. A shaft 57 is attached to each spring holding member 56 so as to penetrate from the outside. The tip of the shaft 57 protrudes inward from the small diameter portion 56 b of the spring holding member 56.

  The coil spring 36 is externally fitted to each shaft 57 between the side plate 38 and the movable base 54, one end is supported by the small diameter portion 56 b of the spring holding member 56, and the other end is disposed on the outer surface of the movable base 54. Are in contact. Thereby, each coil spring 36 presses the movable base 54 toward the fixing belt 31 against the side plate 38. Then, the end face receiving member 35 is urged toward the end face of the fixing belt 31 via the movable base 54, and the elastic member 51 is in contact with the end face of the fixing belt 31.

  The transmissive optical sensor 37 is disposed on the outer periphery of each end face receiving member 35. The transmissive optical sensor 37 has a light emitting part and a light receiving part provided so as to face each other, and the light emitting part and the light receiving part are arranged with the outer peripheral part of each end face receiving member 35 interposed therebetween. As described above, the openings 35a are formed in the outer circumferential portion of the end surface receiving member 35 along the circumferential direction at predetermined intervals, and when the end surface receiving member 35 rotates around the belt end holding member 41, The optical path between the light emitting part and the light receiving part is opened and closed by the part other than the opening part 35a and the opening part 35a. The rotation of the end face receiving member 35 can be detected by the change in the output from the transmissive optical sensor 37 due to the opening and closing of the optical path.

  Further, the fixing device 18 is provided with a regulating member 59 that faces an inner surface of each end surface receiving member 35 (a surface facing the end surface of the fixing belt 31). Each regulating member 59 is positioned on the end face of the fixing belt 31 in a state where the fixing belt 31 is supported by each belt end holding member 41 in a normal state without buckling or deformation (the state shown in FIG. 3). Rather than at a predetermined distance d. This distance d is, for example, the distance that both ends of the fixing belt 31 move toward the center until the possibility that the fixing performance will be affected when a problem such as buckling or deformation occurs in the fixing belt 31. It is. Each end surface receiving member 35 is restricted from sliding in the direction of the end surface of the fixing belt 31 by the surface facing the end surface of the fixing belt 31 coming into contact with the restricting member 59.

  In the fixing device 18 having the above configuration, as shown in FIG. 3, each end face receiving member 35 is biased by the coil spring 36 toward the fixing belt 31 via the movable base 54, and the elastic member 51 is moved. It is in contact with the end face of the fixing belt 31. When the pressure roller 33 is rotated, the fixing belt 31 pressed against the pressure roller 33 by the pressing member 34 is driven to rotate in the opposite direction to the pressure roller 33. Following the rotation of the fixing belt 31, the end surface receiving member 35 rotates around the belt end holding member 41 due to friction between the end surface of the fixing belt 31 and the elastic member 51. When the end face receiving member 35 rotates in this way, the output value of the transmissive optical sensor 37 changes, the rotation of the end face receiving member 35 is detected, and it is monitored that the fixing belt 31 is rotating.

  When the fixing belt 31 is damaged or buckled, both ends of the fixing belt 31 move toward the center. Since each end face contact member 35 is urged toward the end face of the fixing belt 31 by the coil spring 36, when both end portions of the fixing belt 31 move inward in this way, the both end portions of the fixing belt 31 follow. Thus, the end face receiving member 35 also slides inward. Then, when it slides to some extent, it comes into contact with the regulating member 59 and the sliding in the direction of the fixing belt 31 is regulated. When the both end portions of the fixing belt 31 further move inward, the end surface receiving members 35 are separated from the both end surfaces of the fixing belt 31 as shown in FIG. That is, when both end portions of the fixing belt 31 move toward the center until the possibility that the fixing performance is affected is increased, each end surface receiving member 35 is separated from both end surfaces of the fixing belt 31 and each end surface receiving member. The rotation of 35 stops. When the stop of the rotation of each end face receiving member 35 is detected by the transmissive optical sensor 37, measures are taken to stop driving the halogen heater 32 or to notify abnormality.

  As described above, in the fixing device 18 of the present invention, the rotation of the fixing belt 31 can be accurately and stably transmitted to the end face receiving member 35. Therefore, the fixing belt 31 is detected by detecting the rotation of the end face receiving member 35. Can be monitored. If a state in which the rotation of the fixing belt 31 is stopped despite the halogen heater 32 being lit, appropriate measures can be taken promptly. Therefore, it is possible to reliably avoid a situation in which the fixing belt 31 is locally heated and damaged or burned.

  Further, since it is not necessary to mark the fixing belt 31 or to form an opening, the fixing belt 31 is not easily damaged or the transmission type optical sensor 37 is not erroneously detected. Further, since it is not necessary to perform special processing on the fixing belt 31, an increase in cost can be suppressed.

  Furthermore, by providing the regulating member 59, it is possible to quickly and surely detect the breakage or buckling of the fixing belt 31, and thus it is possible to quickly cope with it.

  Further, since the end face receiving member 35 is formed of metal or heat resistant resin, the end face receiving member 35 smoothly slides along the outer peripheral surface of the belt end holding member 41 when rotated by being driven by the fixing belt 31. Further, an elastic member 51 having a higher coefficient of friction than the end surface receiving member 35 is formed on the end surface receiving member 35, and the elastic member 51 contacts the end surface of the fixing belt 31. The frictional force with the end surface is increased, and the end surface receiving member 35 is easily driven by the rotation of the fixing belt 31.

  Note that the frictional force between the end surface receiving member 35 and the movable base 54 is smaller than the frictional force between the end surface of the fixing belt 31 and the elastic member 51. For example, each of the contact surfaces of the movable base 54 and the end surface receiving member 35 is coated with a material having a friction coefficient lower than the friction coefficient of the elastic member 51, or a projection or rib having a cross-sectional arc shape is formed on one of the contact surfaces. It is preferable to provide it.

  Further, by using the transmissive optical sensor 37, the rotation of the end face receiving member 35 can be reliably detected with a simple mechanism. Note that, instead of a transmissive photosensor, a reflective photosensor can also be used. When using a reflection type optical sensor, the rotation of the end face receiving member 35 is detected by detecting the amount of reflected light.

  In the embodiment of the present invention, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the image forming apparatus other than the printer 1 such as a copying machine, a facsimile machine, and a multifunction machine is used. A configuration may be applied.

  Furthermore, since the above description of the embodiment of the present invention describes a preferred embodiment of the image forming apparatus according to the present invention, there may be various technically preferable limitations. The technical scope of the present invention is not limited to these embodiments unless specifically described to limit the present invention. That is, the above-described components in the embodiment of the present invention can be appropriately replaced with existing components and the like, and various variations including combinations with other existing components are possible. The description of the embodiment of the present invention described above does not limit the contents of the invention described in the claims.

1 Printer (image forming device)
18 Fixing device 31 Fixing belt 32 Halogen heater (heat source)
33 Pressure roller (Pressure rotating member)
35 End face receiving member 36 Coil spring (biasing member)
37 Transmission type optical sensor (detection means)
41 Belt end holding member (rotating shaft)
51 Elastic member 59 Restricting member

Claims (6)

A fixing belt which is rotatably provided around a rotation axis and is heated by a heat source;
A pressure rotating member that rotates the fixing belt in a driven manner by rotating in pressure contact with the fixing belt;
Facing the end surface at the outer end face of the rotating axis direction of the fixing belt, and the receiving member rotatably end face which is provided around the in the rotation axis direction can slide and the rotary shaft,
A biasing member that biases the end surface receiving member in the direction of the end surface of the fixing belt;
Detecting means for detecting rotation of the end face receiving member;
In a normal state where the fixing belt is not buckled or deformed, the fixing belt is provided so as to be able to come into contact with the end surface receiving member at a position spaced a predetermined distance inward in the rotational axis direction from the position of the end surface of the fixing belt. A regulating member ;
With
The end surface receiving member is urged by the urging member and rotated by the fixing belt by being pressed against the end face of the fixing belt, wherein from the position of the normal state of the end surface of the fixing belt A fixing device, wherein the rotation of the fixing belt is monitored by detecting the rotation of the end face receiving member by the detecting means until a position separated by a predetermined distance on the inner side in the rotation axis direction . An elastic member is interposed between the end face of the fixing belt and the end face receiving member,
Elastic member fixing device according to claim 1, characterized in that than the surface facing the end surface of the fixing belt of the end surface receiving member is formed with a high friction coefficient material. The end surface receiving member fixing device according to claim 1 or 2, characterized in that it is formed of a heat resistant resin or a metal. Said detecting means, the fixing device according to any one of claims 1 to 3, characterized in that a transmission type optical sensor for detecting the light transmitted through the member receiving said end face. It said detecting means, the fixing device according to any of claims 1-3, characterized in that the reflective optical sensor for detecting light reflected by the member receiving said end face. An image forming apparatus characterized in that it comprises a fixing device according to any one of claims 1-5.

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