JP5530674B2 - Circulating belt device, fixing device and image forming apparatus - Google Patents

Description

  The present invention relates to a revolving belt device that is wound in a detent state between a pair of rollers arranged opposite to each other, a fixing device to which the revolving belt device is applied, and an image forming apparatus to which the fixing device is applied. is there.

  2. Description of the Related Art Conventionally, a circulating belt device used in a fixing device of an image forming apparatus as described in Patent Document 1 is known. This circulating belt device includes a heating roller having a halogen heater therein, a fixing roller disposed opposite to the heating roller, and an endless belt stretched between the heating roller and the fixing roller (in Patent Document 1, an endless belt). ). When the sheet immediately after the toner image conveyed from the image forming unit is transferred passes through the nip portion between the fixing roller and the pressure roller disposed opposite to the endless belt, the sheet is transferred onto the sheet. The toner image receives heat from the endless belt and is subjected to a fixing process.

  In such a revolving belt device, cylindrical outer fitting members made of synthetic resin are fitted into both ends of a heating roller in which a halogen heater is housed. The outer fitting member includes a heat-insulating bush portion having a slit extending over the entire length in the cylinder center direction, and a flange-shaped belt detent portion extending over the entire length in the circumferential direction formed at an edge of the heat-insulating bush portion. And.

  Such outer fitting members are fitted on both ends of the heating roller in a state where the belt detent portions are opposed to each other. The endless belt is wound around the heating roller while being sandwiched between the detent portions of the pair of external fitting members. Therefore, the endless belt at the time of wrapping is prevented by the pair of detent portions during rotation on the heating roller, thereby preventing the endless belt from moving outward in the roller center direction of the heating roller.

JP 2009-133984 A

  By the way, in the circling belt device of Patent Document 1, the stopper member formed on the outer fitting member is formed so that the portion facing the edge of the endless belt is flush with the flat surface. Therefore, the endless belt circulates while the end edge of the endless belt is in surface contact with the detent member, so that annoying noise is likely to occur and the side edge of the endless belt is likely to be damaged. Had.

  The present invention has been made in order to solve such a conventional problem, the generation of noise from the endless belt wound between the first and second rollers is suppressed, and the endless belt It is an object of the present invention to provide a revolving belt device capable of easily avoiding breakage of the side edge, a fixing device to which the revolving belt device is applied, and an image forming apparatus to which the fixing device is applied.

The circulating belt device according to one aspect of the present invention includes first and second rollers that are rotatable about an axis, an endless belt wound around the first and second rollers, and the first and / or first rollers. A belt stopper member disposed at at least one end of the two rollers, and the belt stopper member has a cylindrical body portion having an inner diameter substantially equal to an outer diameter of the first roller or the second roller, and the cylindrical body. An annular flange portion provided on one end side of the portion and projecting from the outer peripheral surface of the first or second roller, and the cylindrical body portion is externally fitted to an end portion of the first or second roller, The annular flange portion has a wall surface facing the side edge portion of the endless belt curved in a direction away from the side edge portion from a rising portion from the first or second roller toward a protruding end of the flange portion. a curved surface, Serial rising portion near vertically, is gradually curve degree is large curved, the side edges of the endless belt is intended that contacts the curved curved and lines, the cylindrical body portion and an annular the close stop member The flange portion is provided with slits extending in the axial direction of the first or second roller over the flange portions, and each corner portion in the direction toward the cylindrical center at the opposite edges on the wall surface side of the slit. Is characterized in that an R surface is formed in a state where each of the corners is cut off in a region corresponding to the rising portion .

  According to such a configuration, since the wall surface of the flange portion facing the side edge of the endless belt is a curved surface that is curved away from the side edge of the endless belt, the side edge of the endless belt is Since only the corners of the belt contact with the flange portion of the belt detent member are so-called line contact, generation of noise due to a large contact area as in the case of conventional surface contact is suppressed. Moreover, since the contact area between the endless belt side edge portion and the flange portion is small, the end surface of the endless belt is hardly damaged.

Further, the curved surface is, the closer the vertically rising portion of the first or second roller, Ru curved der gradually curve degree is increased.

  According to such a configuration, in the state where the endless belt is rotating, the endless belt is in contact with a sharp rising portion where the corner portion on the inner surface side of the side edge portion is close to the vertical of the curved surface of the flange portion. It is possible to effectively restrain the flange portion from advancing toward the outer surface in the radial direction.

The belt detent member includes a cylindrical body portion having an inner diameter substantially equal to the outer diameter of the first roller or the second roller, and an annular flange portion provided on one end side of the cylindrical body portion, the cylindrical body portion is fitted to the end portion of the first or the second roller, the curved surface on the belt side edges and opposing surfaces of the annular flange portion that is formed.

  According to this configuration, the annular flange portion having the belt detent portion is formed at both ends of the first and second rollers by a simple operation of fitting the cylindrical portion of the belt detent member into the end portion of the roller. Can be made.

In addition , a slit extending in the axial direction of the first or second roller is provided in the cylindrical body portion and the annular flange portion of the detent member, and the slits face each other on the wall surface side. At each corner of the end edge in the direction toward the cylindrical center, an R surface is formed in a state where each corner is scraped off in a region corresponding to the rising portion .

According to such a configuration, when the side edge surface of the endless belt that is circulating comes into contact with the annular flange portion, the side edge surface of the endless belt is in the direction toward the cylindrical center at the opposite edges of the slit. It abuts on the R surface formed in a state of being cut off at each corner. Therefore, when the R surface is not formed as in the prior art, the edge surface of the endless belt is caught at the time of contact with the sharp corner of the slit, and abnormal noise is generated . According to the configuration, occurrence of abnormal noise is suppressed by the R surface that is not caught.

Fixing equipment according to another aspect of the present invention is a fixing apparatus which performs a fixing process by heating to the transferred paper toner image, the heat source is a heating roller is decorated, the heating roller and disposed opposite A fixing roller, a fixing belt wound around the fixing roller and the heating roller, and a pressure roller disposed to face the fixing roller via the fixing belt, the heating roller, the fixing roller and said fixing belt is characterized in that a first roller, the second roller and the endless belt in the circumferential belt device.

According to this configuration, the fixing device can enjoy the operational effects provided in the above- described circumferential belt device.

Further, the image forming equipment according to another aspect of the present invention has been transferred and the image forming unit for transferring a toner image on a sheet by performing a predetermined image forming process based on the image information, the paper by the image forming unit Toner The image forming apparatus includes the above-described fixing device that performs a fixing process on the sheet with respect to the image.

According to this configuration, the image forming apparatus can enjoy the functions and effects provided by the fixing device described above .

  According to the circulating belt device according to the present invention, the side edge portion of the endless belt is wound around the roller by so-called line contact in which only the corner portion on the peripheral surface side of the roller is in contact with the flange portion of the belt detent member. Therefore, it is possible to prevent the noise generated during the conventional surface contact from occurring.

  According to the fixing device according to the present invention, the fixing device can enjoy the effects provided by the circulating belt device according to the present invention.

  According to the image forming apparatus of the present invention, the image forming apparatus can enjoy the functions and effects provided by the fixing device of the present invention.

FIG. 3 is a front sectional view for explaining an embodiment of the internal structure of the image forming apparatus to which the fixing device according to the invention is applied. 2 is a front sectional view showing an outline of an embodiment of a fixing device 20. FIG. It is a disassembled perspective view which shows one Embodiment of a housing | casing. FIG. 4 is an assembled perspective view of the housing shown in FIG. 3. It is a perspective view which shows the state in which a belt detent member is applied to a heating roller, (A) is a state immediately before a belt detent member is attached to a heating roller, and (B) is a state in which a belt detent member is installed. A state in which the fixing belt is wound between the heated roller and the fixing roller, (C) shows an enlarged view of the belt detent member. FIG. 6 is a cross-sectional view taken along the line VI-VI of the front belt stopper member shown in FIG. 5. It is the elements on larger scale in the circle of FIG.

  First, an image forming apparatus to which the fixing device according to the present invention is applied will be described. FIG. 1 is an explanatory front sectional view for explaining an embodiment of an internal structure of an image forming apparatus 10 to which a fixing device 20 according to the present invention is applied. In FIG. 1, the X direction is referred to as the left-right direction, and in particular, -X is referred to as the left and + X is referred to as the right.

  As shown in FIG. 1, an image forming apparatus 10 according to the present embodiment is used as a printer, and is attached to a box-shaped apparatus main body 11 and a side surface of the apparatus main body 11 so as to be openable and closable. And a cover body 19.

  The apparatus main body 11 includes an image forming unit 12 that forms an image based on image information transmitted from an external device such as a computer, and a fixing process performed on the toner image formed by the image forming unit 12 and transferred to the paper P. A fixing unit 13 for applying toner, a sheet storage unit 14 for storing a transfer sheet, and a toner supply unit 15 for supplying toner to the image forming unit 12, and an upper portion of the apparatus main body 11 after the fixing process. A paper discharge section 16 is formed through which the paper P is discharged.

  At an appropriate position on the upper surface of the apparatus main body 11, an operation panel (not shown) for inputting the output conditions of the paper P and the like is provided. This operation panel is provided with a power key, a start button (not shown), various keys for inputting output conditions, and the like.

  The image forming unit 12 forms a toner image on the paper P fed from the paper storage unit 14, and in this embodiment, the image forming unit 12 is sequentially arranged from the upstream side (right side in FIG. 1) to the downstream side. The magenta unit 12M using the magenta toner (developer), the cyan unit 12C using the cyan toner, the yellow unit 12Y using the yellow toner, and the black using the black toner. Unit 12K.

  Each of the units 12M, 12C, 12Y, and 12K is provided with a photosensitive drum 121 and a developing device 122, respectively. The photosensitive drum 121 is for forming an electrostatic latent image and a toner image along the electrostatic latent image on the peripheral surface. Each photosensitive drum 121 receives supply of toner from the corresponding developing device 122 while rotating clockwise in FIG. Each developing device 122 is supplied with toner from the toner supply unit 15. Each of the photosensitive drums 121 is driven and rotated by a photosensitive drum driving mechanism (not shown).

  A charging device 123 is provided immediately below each photosensitive drum 121, and an exposure device 124 is provided further below each charging device 123. Each photosensitive drum 121 is uniformly charged at its peripheral surface by the charging device 123, and laser light corresponding to each color based on image data input from a computer or the like is charged from the exposure device 124 to the photosensitive member after charging. Irradiates the circumferential surface of the drum 121. Thereby, an electrostatic latent image is formed on the peripheral surface of each photosensitive drum 121. By supplying toner from the developing device 122 to the electrostatic latent image, a toner image is formed on the peripheral surface of the photosensitive drum 121.

  A transfer belt 125 stretched between the driving roller 125 a and the driven roller 125 b is provided at a position above the photosensitive drum 121 so as to contact the photosensitive drum 121. The transfer belt 125 is driven against a peripheral surface of the photosensitive drum 121 by a transfer roller 126 provided corresponding to each photosensitive drum 121, and is driven with a driving roller 125a and a driven roller while being synchronized with the photosensitive drum 121. Circulate between 125b.

  Therefore, when the transfer belt 125 circulates, the toner image of the magenta toner is transferred to the surface of the transfer belt 125 by the photosensitive drum 121 of the magenta unit 12M, and then the photosensitive member of the cyan unit 12C is located at the same position on the transfer belt 125. The transfer of the cyan toner image by the drum 121 is performed in the overcoating state, and then the transfer of the yellow toner image by the photosensitive drum 121 of the yellow unit 12Y is performed in the overcoating state at the same position on the transfer belt 125. Then, the transfer of the black toner image by the photosensitive drum 121 of the last black unit 12K is performed in an overcoated state, whereby a color toner image is formed on the surface of the transfer belt 125. The color toner image formed on the surface of the transfer belt 125 is transferred to the paper P conveyed from the paper storage unit 14.

  A cleaning device 127 that removes and cleans residual toner on the peripheral surface of the photosensitive drum 121 is provided at the right side of each photosensitive drum 121 in FIG. The peripheral surface of the photosensitive drum 121 cleaned by the cleaning device 127 goes to the charging device 123 for a new charging process.

  Waste toner removed from the peripheral surface of the photosensitive drum 121 by the cleaning device 127 is collected and stored in a toner collection bottle (not shown) through a predetermined path.

  At the left position of the image forming unit 12 in FIG. 1, a paper conveyance path 111 extending in the vertical direction along the right surface of the cover body 19 is formed. The sheet conveying path 111 is provided with a pair of conveying rollers 112 at appropriate positions, and the sheet P fed from the sheet storing unit 14 is transferred to the transfer belt 125 that is wound around the driving roller 125 a by the driving of the conveying roller pair 112. It is conveyed toward.

  In the sheet conveyance path 111, a second transfer roller 113 that is in contact with the surface of the transfer belt 125 is provided at a position facing the driving roller 125 a, and the sheet P being conveyed along the sheet conveyance path 111 is separated from the transfer belt 125. The toner image on the transfer belt 125 is transferred onto the paper P by being pressed and sandwiched between the second transfer roller 113.

  The fixing unit 13 performs a fixing process on the toner image on the paper transferred by the image forming unit 12. The fixing unit 13 is provided with a fixing device 20. The fixing device 20 will be described in detail later with reference to FIGS.

  The color-printed paper P that has been subjected to the fixing process passes through a paper discharge conveyance path 114 extended from the upper part of the fixing unit 13 to a paper discharge tray 161 of a paper discharge unit 16 provided at the top of the apparatus main body 11. It will be discharged towards.

  The paper storage unit 14 includes a paper tray 141 that is detachably mounted at a position below the exposure device 124 in the apparatus main body 11. The paper tray 141 is configured to include a box body whose upper surface is open on the entire surface, and can store a paper bundle P1 in which a plurality of paper sheets P are stacked. The uppermost sheet P of the sheet bundle P1 stored in the sheet tray 141 is fed from the sheet bundle P1 toward the sheet conveyance path 111 by driving the pickup roller 142 from the upper surface of the downstream end (left end in FIG. 1). The paper P fed out one by one is fed toward the nip portion between the second transfer roller 113 and the transfer belt 125 in the image forming unit 12 through the paper conveyance path 111 by driving the conveyance roller pair 112.

  The toner replenishing unit 15 is provided with four toner cartridges 151 corresponding to the units 12M, 12C, 12Y, and 12K of the image forming unit 12, respectively. Then, the toner is supplied from the corresponding toner cartridge 151 corresponding to the developing device 122 of each of the units 12M, 12C, 12Y, and 12K when the remaining amount decreases.

  The cover body 19 is placed on the left side in FIG. 1 of the image forming unit 12, the fixing unit 13, and the sheet storage unit 14 by changing the posture between a closed posture S1 (shown by a solid line in FIG. 1) and an open posture S2. It can be opened and closed. The cover body 19 is normally set in a closed position S1 so that the sheet from the sheet storage unit 14 is conveyed toward the second transfer roller 113 between the image forming unit 12 and the left side in FIG. The sheet conveyance path 111 is formed.

  Then, when a paper jam occurs in the conveying roller pair 112 or the fixing unit 13, the cover body 19 is opened (that is, the posture is changed from the closed posture S1 to the open posture S2), and thereby the image forming unit 12 exposed to the outside and The jammed paper can be easily removed from the fixing unit 13.

  The cover body 19 is reversely conveyed for duplex printing in which the paper P that has passed through the second transfer roller 113 is reversed and then returned to the paper conveyance path 111 for printing on the back side. Although a path is provided, description thereof is omitted.

  FIG. 2 is a front sectional view showing an outline of an embodiment of the fixing device 20. In FIG. 2, the XX direction is referred to as the left-right direction, and in particular, -X is referred to as the left and + X is referred to as the right. As shown in FIG. 2, the fixing device 20 includes a housing 80 having a deformed box shape, a heating roller (first roller) 30, and a fixing roller (second roller) disposed to face the heating roller 30. 40, a fixing belt (endless belt) 50 stretched between the fixing roller 40 and the heating roller 30, and a pressure roller 60 opposed to the fixing belt 50 with the fixing roller 40 interposed therebetween. It is configured by being.

  In the bottom plate of the housing 80, an introduction opening for introducing the paper P, which has been fed through the paper conveyance path 111, to a position slightly to the left of the central portion in the left-right direction in FIG. 21 is provided at a position facing the introduction opening 21 on the top plate of the housing 80, and a lead-out opening 22 for leading out the sheet P after the fixing process is provided.

  The heating roller 30 is provided at a right position in the housing 80 in FIG. 2 so as to extend in the paper width direction orthogonal to the paper transport direction. The heating roller 30 includes an aluminum cylindrical tube shaft 31 that is rotatably supported by a housing 80. Fluorine resin processing with PFA (tetrafluoroethylene perfluoroalkyl vinyl ether copolymer) or the like is performed around the cylindrical shaft 31. An energization heating element 32 made of a halogen lamp or the like is disposed inside the cylindrical shaft 31. The fixing belt 50 is wound around the cylindrical shaft 31 of the heating roller 30.

  The fixing roller 40 is provided in the housing 80 such that the circumferential surface faces the left position of the heating roller 30 at a position where the center of rotation is slightly to the right of the introduction opening 21. The fixing roller 40 includes a fixing roller mandrel 41 made of a metal material such as an aluminum alloy, and an elastic layer 42 made of a cylindrical foamable silicone rubber that is concentrically and integrally fitted to the fixing roller mandrel 41. It has.

  The fixing belt 50 is stretched between the cylindrical shaft 31 of the heating roller 30 and the elastic layer 42 of the fixing roller 40 in a predetermined tension state. In this embodiment, the fixing belt 50 has a nickel electroformed belt as a core material, a silicon rubber layer laminated on the front and back surfaces of the core material, and a PFA film layer on the outer peripheral side.

  Incidentally, in this embodiment, the nickel core material has a thickness dimension set to 90 μm, the silicon rubber layer has a thickness dimension set to 200 to 300 μm, and the PFA film layer has a thickness dimension of 30 μm. However, the thickness dimension of each material is not limited to these values, and is appropriately set according to the situation.

  The pressure roller 60 is disposed in the housing 80 such that the circumferential surface thereof is in contact with the circumferential surface of the fixing roller 40 via the fixing belt 50 at a position where the center of rotation is slightly to the left of the introduction opening 21. Has been. The pressure roller 60 includes a pressure roller main body 61 made of an aluminum alloy cylinder, and an externally fitted cylindrical elastic body made of silicon rubber and provided concentrically and integrally with the pressure roller main body 61. A layer 62 and a synthetic resin film 63 made of PFA or the like coated on the peripheral surface of the elastic body layer 62 are provided.

  The contact position between the peripheral surface of the elastic layer 62 via the synthetic resin film 63 and the peripheral surface of the elastic layer 42 via the fixing belt 50 (that is, the position where the fixing belt 50 and the synthetic resin film 63 contact). ), A nip portion N is formed to nip the sheet P fed into the housing 80 through the introduction opening 21.

  The pressure roller main body 61 is made of a metal material such as an aluminum alloy, while the elastic body layer 62 is made of an elastic material such as silicone rubber, whereby the fixing belt 50 is formed in the nip portion N. Is recessed in the radial direction due to elastic deformation due to contact with the fixing roller 40 via.

  In such a pressure roller 60, the driving force of a drive motor (not shown) provided at an appropriate position of the casing 80 is transmitted to the pressure roller body 61 via a predetermined reduction mechanism (not shown). The roller body 61 is driven to rotate about the axis. The driving rotation of the pressure roller 60 is transmitted to the fixing belt 50 that is in pressure contact with the pressure roller 60, whereby the fixing belt 50 circulates between the heating roller 30 and the fixing roller 40.

  Accordingly, the fixing belt 50 is entirely heated by the heat transfer from the cylindrical shaft 31 of the heating roller 30 heated by the radiant heat from the energizing heating element 32 while rotating.

  Since the fixing device 20 is configured in this manner, the toner image is transferred by passing between the second transfer roller 113 (FIG. 1) and the transfer belt 125 wound around the drive roller 125a. The applied paper P is supplied to the nip portion N between the fixing roller 40 and the fixing belt 50 stretched around the fixing roller 40 through the introduction opening 21, and the rotation of the pressure roller 60 and the fixing belt 50. By passing through the nip portion N in a round, the heat of the fixing belt 50 is transferred to the toner image on the surface of the paper P, and the paper P is subjected to a fixing process by heat treatment.

  The paper P after the fixing process is led out of the housing 80 through the lead-out opening 22 in accordance with the rotation of the fixing belt 50 and the rotation of the pressure roller 60 that follows the fixing belt 50. It is discharged to the in-body discharge tray 115 (FIG. 1).

  Hereinafter, the housing 80 to which the heating roller 30, the fixing roller 40, and the pressure roller 60 are mounted will be described with reference to FIGS. FIG. 3 is an exploded perspective view for explaining the housing 80, and FIG. 4 is an assembled perspective view thereof. 3 and 4, the XX direction is referred to as the left-right direction, and the Y-Y direction is referred to as the front-rear direction. In particular, the -X direction is leftward, the + X direction is rightward, the -Y direction is forward, and the + Y direction is forward. It is called the back. Incidentally, FIGS. 3 and 4 are so-called principle diagrams that are simplified for easy understanding of the casing 80, and therefore, detailed design matters may be omitted or adjusted. Show. In FIG. 3, only the right side of the housing 80 is shown for the sake of space, and the left side formed symmetrically is omitted.

  First, as shown in FIG. 3, the casing 80 is mounted with the fixing belt side casing 81 on which the heating roller 30, the fixing roller 40, and the fixing belt 50 are mounted, and the pressure roller 60. And a pressure roller side housing 87 disposed opposite to the fixing belt side housing 81.

  The fixing belt-side casing 81 has a pair of side plates 82 disposed opposite to each side end of the fixing belt 50 stretched between the heating roller 30 and the fixing roller 40, and each side plate while supporting the heating roller 30. 82, a pair of movable plates 83 provided so as to be horizontally movable, a construction plate 84 installed between the lower edges of the pair of side plates 82, and the heating roller 30 between the pair of side plates 82, above and behind A U-shaped cover body 85 having a U-shape in a side view mounted at a position corresponding to the lower side, and a terminal block member 86 that relays power supplied to the energization heating element 32 are provided.

  Each side plate 82 is formed with a square hole 821 facing the end of the heating roller 30 at the rear half position, and a bearing mounting hole facing the fixing roller 40 at the front half position. 822 is drilled. Each side plate 82 is provided with a bracket 823 extending rearward from the rear position of the square hole 821, and a projecting plate 824 projecting upward from the rear position. ing. A first support piece 835 for inserting a connecting rod 801, which will be described later, is provided on the upper rear edge of each of the projecting plates 824 so as to project in directions opposite to each other. Yes.

  The pair of movable plates 83 support the bearings B that are externally fitted to the respective end portions of the heating roller 30, and bearing mounting holes 831 into which the bearings B are fitted are formed in the center. The movable plate 83 can be moved in the front-rear direction while being guided by a pair of guide rails 821a arranged to be opposed to the upper and lower sides of the square holes 821 on the opposed surfaces of the pair of side plates 82. The bearings B are inserted into the respective bearing mounting holes 831 of the pair of movable plates 83 supported by the guide rails 821a, so that the heating roller 30 can rotate about the axis and can move back and forth. 82.

  A front end portion of the first coil spring 832 is mounted at the center position of the rear edge portion of the movable plate 83. The rear end of the first coil spring 832 has a locking groove recessed in the rear edge of the bracket 823 as shown in FIG. 4 with the movable plate 83 supported by the pair of guide rails 821a. The movable plate 83 is urged toward the rear by being locked by 823a.

  The erection plate 84 is notched rearward at the front position, so that the sheet P is inserted into the nip portion N in a state where the fixing belt side casing 81 is coupled to the pressure roller side casing 87. An introduction opening 21 leading to is secured.

  The U-shaped cover body 85 includes a rear plate 851 that covers the rear of the fixing belt 50 that is wound around the heating roller 30, and the fixing belt 50 that extends forward from the upper edge of the rear plate 851. The top plate 852 covers the rear upper surface of the rear plate 851 and the bottom plate 853 extending forward from the lower edge of the rear plate 851. When the bottom plate 853 is laminated on the lower surface of the erection plate 84, it is fixed to the erection plate 84 with screws or the like, so that a fixing belt side casing 81 that covers the fixing belt 50 is formed.

  A predetermined number of through holes 854 (only one is shown in FIG. 3) are formed at appropriate positions on the front edge of the bottom plate 853 of the U-shaped cover body 85, and screws S are passed through these through holes 854. Then, the pressure roller side housing 87 is connected to the fixing belt side housing 81 by screwing it onto a bottom plate 89 (described later) of the pressure roller housing 87.

  The terminal block member 86 relays the electric power supplied to the energization heating element 32 in a state where the energization heating element 32 is supported. The terminal block member 86 includes a mounting plate 861 that is attached to the side plate 82 by screws or the like in a state in which the square hole 821 of the side plate 82 of the fixing belt side housing 81 is closed, and a substantially center in the vertical direction of the mounting plate 861. And a terminal block 862 extending in the front-rear direction and projecting outward from the position.

  The mounting plate 861 is provided with a circular hole 861 a having a slightly smaller diameter than the bearing mounting hole 831 of the movable plate 83. The end face of the energization heating element 32 is opposed to the terminal block 862 through the circular hole 861a. A terminal piece 862a corresponding to the energization heating element 32 is attached to the terminal block 862 with screws, and power is supplied to the energization heating element 32 through the terminal piece 862a.

  Bearings B are fitted on both ends of the heating roller 30, respectively. The heating roller 30 is mounted on the fixing belt side casing 81 by fitting the bearing B into the bearing mounting hole 831 of the movable plate 83 supported between the pair of upper and lower guide rails 821a.

  The fixing roller 40 has a pair of shaft cylinders 43 that are concentric and project from opposite ends in opposite directions, and bearings B are mounted on these shaft cylinders 43. The fixing roller 40 is mounted on the fixing belt side housing 81 so as to be rotatable about the axis center by fitting the bearing B mounted on the shaft cylinder 43 into the bearing mounting hole 822 of the side plate 82.

  The pressure roller side housing 87 has a pair of side plates 88 in the left-right direction, a bottom plate 89 constructed between the lower edges of the pair of side plates 88, and a vertical dimension standing from the front edge of the side plate 88. Is provided with a front plate 90 that is substantially half of the side plate 88 and an inclined top plate 91 that is inclined upward from the upper edge of the front plate 90 toward the rear.

  The inner dimension between the pair of side plates 88 is set to be slightly larger than the outer dimension between the pair of side plates 82 of the fixing belt side casing 81, whereby the pressure roller side casing 87 is fixed to the fixing belt side casing. 81 can be externally fitted. Each side plate 88 is provided with a bearing mounting hole 881 at a position ahead of the center in the front-rear direction.

  On the other hand, the pressure roller 60 has a pair of shaft cylinders 64 that are concentric from both ends and project in opposite directions, and bearings B are mounted on these cylinders 64. The pressure roller 60 is attached to the pressure roller side housing 87 so as to be rotatable around the axis center by fitting the bearing B attached to the shaft cylinder 64 into the bearing attachment hole 881 of the side plate 88.

  Further, in a state where the pressure roller 60 is mounted on the pressure roller side casing 87 via the bearing B, an E-ring 65 that is a retaining member is attached to the shaft cylinder 64 protruding to the outside from the bearing mounting hole 881. As a result, the mounting state of the pressure roller 60 to the pressure roller side casing 87 is stabilized.

  The bottom plate 89 is provided with a long rectangular hole 891 extending in the left-right direction at a substantially central position in the front-rear direction, and is screwed at the rear edge so as to face the through hole 854 of the U-shaped cover body 85. A provided screw hole 892 is provided. The long rectangular hole 891 has an installation position corresponding to the introduction opening 21 (FIG. 2) through which the paper P is introduced into the housing 80.

  Then, the screw S through the through hole 854 in a state in which the pressure roller side housing 87 is fitted on the fixing belt side housing 81 so that the bottom plate 89 abuts the lower surface of the bottom plate 853 of the U-shaped cover body 85. The pressure roller side housing 87 is connected to the fixing belt side housing 81 so as to be able to swing around the screw S. Further, in a state where the pressure roller side casing 87 is connected to the fixing belt side casing 81, the peripheral surface of the pressure roller 60 is added so as to face the peripheral surface of the fixing roller 40 through the fixing belt 50. The installation position of the pressure roller 60 is set.

  The inclined top plate 91 has a cutout portion 911 formed by cutting a front portion thereof in a U shape in plan view. Left and right directions that are set up on both sides of the notch 911 from the front edge of the inclined top plate 91 and are positioned so as to face the first support piece 835 of the fixing belt side casing 81. A pair of second support pieces 912 is provided.

  Then, with the first and second support pieces 835 and 912 facing each other in the front-rear direction, the connecting rod 801 is inserted into the through hole formed in the first and second support pieces 835 and 912 from the rear side. As a result, the upper part of the fixing belt side casing 81 and the pressure roller side casing 87 are connected to each other. The connecting rod 801 is provided with a head 802 having a diameter larger than the diameter of the connecting rod 801 at the rear end, and an annular groove 803 is recessed at the front end.

  When the connecting rod 801 is inserted through the first and second support pieces 835 and 912 from the rear, as shown in FIG. 4, a second coil spring 804 is externally fitted in a compressed state on the front end side. In this state, the C ring 805 is fitted into the annular groove 803. Therefore, in a state where the fixing belt side casing 81 and the pressure roller side casing 87 are connected to each other (FIG. 4), the biasing force of the second coil spring 804 causes the fixing belt side casing 81 and the pressure roller side casing. The body 87 is urged toward the direction approaching the screw S by the urging force of the second coil spring 804, whereby the pressure roller 60 is pressed against the fixing roller 40 via the fixing belt 50. The

  Further, the heating roller 30 is urged toward the direction away from the fixing roller 40 via the movable plate 83 and the bearing B by the urging force of the first coil spring 832, whereby the fixing belt 50 is in a tension state. Maintained.

  In this embodiment, a belt detent member 70 is applied to the heating roller 30. Hereinafter, the belt detent member 70 will be described with reference to FIGS. 5 and 6. FIG. 5 is a perspective view showing a state in which the belt detent member 70 is applied to the heating roller 30, and FIG. 5A is a state immediately before the belt detent member 70 is attached to the heating roller 30. 5B is a state in which the fixing belt 50 is wound between the heating roller 30 to which the belt stopper member 70 is mounted and the fixing roller 40, and FIG. 5C is an enlarged view of the belt stopper member. Respectively.

  6 is a cross-sectional view taken along the line VI-VI of the belt-side stopper member 70 on the front side shown in FIG. 5, and FIG. 7 is a partially enlarged view in the circle of FIG. 5 and 6, the X direction is referred to as the left-right direction, and the Y direction is referred to as the front-rear direction. In particular, -X is referred to as the left, + X as the right, -Y as the front, and + Y as the rear.

  First, as shown in FIG. 5, the belt detent member 70 is a pair of heat insulating bushes (cylindrical body portions) 71 made of synthetic resin that are externally fitted to both end portions of the cylindrical shaft 31 of the heating roller 30 so as to be integrally rotatable. A detent flange (flange portion, annular flange) 72 formed on each of the opposing edge surfaces of the pair of heat insulating bushes 71, and an annular formed on the opposite surface of each detent flange 72 over the entire circumference. A curved surface (curved curved surface) 73.

  On the other hand, the cylinder shaft 31 to which the belt detent member 70 is mounted is concentrically extended from the central cylinder shaft body 311 and the front and rear ends of the cylinder shaft body 311 in opposite directions. A pair of front and rear small-diameter cylindrical portions 312 having a slightly smaller diameter than the cylindrical shaft main body 311 is provided. The belt detent member 70 is attached to the heating roller 30 by the heat-insulating bush 71 being fitted around the front and rear small-diameter cylindrical portions 312 respectively.

  The heat insulating bush 71 is formed in a cylindrical shape penetrating in the front-rear direction, and the inner diameter dimension is set slightly smaller than the outer diameter dimension of the small diameter cylindrical portion 312 of the cylindrical shaft 31 (the outer diameter of the heating roller 30 and the heat insulating capacity). The inner diameter of the bush 71 is set to be substantially the same). The heat insulating bush 71 is provided with a cut groove (slit) 711 formed by cutting over the entire length in the front-rear direction.

  When the belt detent member 70 is attached to the small diameter cylindrical portion 312, the heat insulating bush 71 is externally fitted to the small diameter cylindrical portion 312 with the cut groove 711 being expanded by elastically deforming the heat insulating bush 71. By doing so, the heat insulating bush 71 is clamped by a restoring force of elastic deformation with respect to the small diameter cylindrical portion 312 and is fixed so as to be integrally rotatable.

  Further, the heat insulating bush 71 is provided with an inner flange (annular flange portion) 721 at the edge on the opposite side to the detent flange 72. The inner flange 721 is formed by concentrically projecting from the inner peripheral surface of the end portion (the front end portion in the example shown in FIG. 6) of the heat insulating bush 71 toward the center by a predetermined dimension over the entire circumference. . The inner diameter dimension of the inner flange 721 is set to be the same as the inner diameter dimension of the small diameter cylindrical portion 312 of the cylindrical shaft 31. Accordingly, when the heat insulating bush 71 is fitted onto the small diameter cylindrical portion 312, the inner flange 721 is abutted against the edge of the small diameter cylindrical portion 312, whereby the heat insulating bush 71 is positioned and the cylindrical shaft 31 of the heating roller 30. It is attached to.

  When the fixing belt 50 meanders and moves to the side (front side in the example shown in FIG. 7), the offset flange 72 contacts the edge of the fixing belt 50. It is for touching and stopping this. In the present embodiment, the protruding amount of the detent flange 72 toward the radially outward direction from the heat insulating bush 71 is set to be approximately twice the thickness dimension of the heat insulating bush 71. The meandering fixing belt 50 is prevented from climbing over the heat-insulating bush 71 and coming to the side when the edge of the fixing belt 50 abuts against the detent flange 72.

  The annular curved surface 73 is formed in a convex arc shape toward the fixing belt 50 in a sectional view as shown in FIG. The annular curved surface 73 is set so that the rising portion of the cylindrical shaft 31 from the peripheral surface of the small diameter cylindrical portion 312 is nearly vertical and the degree of curvature gradually increases. Therefore, in a state where the side edge portion 51 of the fixing belt 50 is in contact with the annular curved surface 73 of the belt detent member 70, as shown in FIG. 7, the back side corner portion 511 of the side edge portion 51 is annular in a sectional view. It is stopped by a point contact (a line contact over the half circumference of the annular curved surface 73) in the immediate vicinity of the rising portion of the curved surface 73. As a result, even when the cylindrical roller 31 rotates the fixing belt 50 by the rotation of the heating roller 30, the generation of noise that occurs when the conventional side edge 51 is in surface contact with the detent flange is suppressed. can do. Further, since the rising portion of the annular curved surface 73 is nearly vertical, it is possible to suppress the advancing of the fixing belt 50.

  Incidentally, in this embodiment, when the thickness dimension in the radial direction of the detent flange 72 is L1 and the dimension in the front-rear direction of the annular curved surface 73 is L2, the value of “L1 / L2” is within the range of 2 to 1. The values of L1 and L2 are set so that The value of L2 is set to a value within the range of 0.1 to 3.0 mm. It has been experimentally confirmed that by setting the values of L1 and L2 within such a range, the generation of abnormal noise when the fixing belt 50 goes around can be suppressed.

  In this embodiment, the cylindrical cores at the opposite edges on the fixing belt 50 side of the cut grooves 711 extending in the cylindrical direction formed in the heat insulating bush 71 and the locking flange 72 of the belt locking member 70 are provided. At each corner in the direction of heading, as shown in FIGS. 5C and 7, an R surface 731 in a state where each is cut off is formed.

  Therefore, when the rotating fixing belt 50 is in contact with the detent flange 72, the side edge surface of the fixing belt 50 is in contact with the gentle R surface 731. Therefore, when the R surface 731 is not formed as in the prior art, the edge surface of the fixing belt 50 is caught at the time of contact with the sharp corner of the cut groove 711, and an abnormal noise is generated. However, in the present embodiment, since the side edge surface of the fixing belt 50 is guided to the R surface 731, the side edge surface does not get caught, and as a result, it is possible to reliably suppress the generation of abnormal noise. it can.

  As described above in detail, the circulating belt device according to the present embodiment is applied to the fixing device 20, and includes a heating roller 30 that can rotate around its axis, and a fixing roller that is disposed to face the heating roller 30. 40, a fixing belt 50 wound around the heating roller 30 and the fixing roller 40, and a pair of belt detent members 70 provided at both ends of the heating roller 30.

  The belt detent member 70 has a detent flange 72 protruding from the outer peripheral surface of the heating roller 30, and the detent flange 72 has a wall surface facing the side edge of the fixing belt 50 from the side edge. Since the side surface 51 of the fixing belt 50 is in contact with the detent flange 72 of the belt detent member 70, the side edge 51 of the fixing belt 50 is in contact with the detent flange 72 of the belt. In contact. Therefore, it is possible to suppress the generation of noise due to a large contact area such as conventional surface contact. Further, since the contact area between the side edge portion 51 of the fixing belt 50 and the detent flange 72 is small, the side edge portion 51 of the fixing belt 50 can be hardly damaged.

  The annular curved surface 73 of the belt detent member 70 is set to be curved so that the rising portion from the heating roller 30 is nearly vertical and the degree of curvature gradually increases in a cross-sectional view passing through the center line of the cylindrical shaft 31. Therefore, in the state in which the fixing belt 50 is rotating, the fixing belt 50 has a back side corner portion 511 that is a corner portion on the inner surface side of the side edge portion 51, which is close to the perpendicular to the annular curved surface 73 of the detent flange 72. Touch a steep rise. Therefore, it is possible to effectively suppress the fixing belt 50 from advancing on the annular curved surface 73 of the detent flange 72 toward the radially outer side of the cylindrical shaft 31 of the heating roller 30.

  In addition, the belt detent member 70 includes a heat insulating bush 71 having an inner diameter substantially equal to the outer diameter of the small diameter cylindrical portion 312 of the heating roller 30, and an annular detent flange 72 provided on one end side of the heat insulating bush 71. It is configured with. The heat insulating bush 71 has an annular curved surface 73, and the annular curved surface 73 is formed on the surface of the annular curved surface 73 that faces the side edge 51 of the fixing belt 50.

  By configuring the belt detent member 70 in this way, the heat insulating bush 71 of the belt detent member 70 is fitted to both ends of the heating roller 30 by a simple operation of fitting the end portion of the small diameter cylindrical portion 312 of the heating roller 30. Further, an annular detent flange 72 having an annular curved surface 73 can be formed, and the workability of the work of assembling the belt detent member 70 can be improved.

  In addition, the fixing device 20 in which such a belt stopper member 70 is employed can enjoy the effects provided by the belt stopper member 70.

  The present invention is not limited to the above embodiment, and includes the following contents.

  (1) In the above embodiment, the printer is described as an example of the image forming apparatus 10 to which the fixing device 20 including the belt detent member 70 is applied. However, as the image forming apparatus, a copying machine or a facsimile apparatus is used. It may be adopted.

  (2) In the above embodiment, the belt detent member 70 is provided only on the heating roller 30, but it may also be provided on the fixing roller 40.

  (3) In the above embodiment, in order to form the detent flange 72 having the annular curved surface 73 on the cylindrical shaft 31 of the heating roller 30, the belt detent member 70 having these is used as the small diameter cylindrical portion of the heating roller 30. Although it is made to carry out the outer fitting to 312, you may manufacture the cylindrical shaft 31 in which the offset flange 72 was integrally provided from the beginning instead of doing this.

  (4) In the above-described embodiment, the cylindrical shaft 31 includes the cylindrical shaft main body 311 and a pair of small-diameter cylindrical portions 312 extending concentrically outward from both ends of the cylindrical shaft main body 311. Although the belt detent member 70 is externally fitted to the small diameter cylindrical portion 312, the belt detent member 70 is directly externally fitted to the cylindrical shaft main body 311 without providing the small diameter cylindrical portion 312. Good.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 11 Apparatus main body 111 Paper conveyance path 112 Conveyance roller pair 113 Transfer roller 114 Discharge conveyance path 115 In-body discharge tray 12 Image forming unit 12M Magenta unit 12C Cyan unit 12Y Yellow unit 12K Black unit 121 Photosensitive drum 122 Developing device 123 Charging device 124 Exposure device 125 Transfer belt 125a Drive roller 125b Driven roller 126 Transfer roller 127 Cleaning device 13 Fixing unit 14 Paper storage unit 141 Paper tray 142 Pickup roller 15 Toner replenishment unit 151 Toner cartridge 16 Paper discharge Section 161 Discharge tray 19 Cover body 20 Fixing device 21 Introducing opening 22 Deriving opening 30 Heating roller (first roller)
31 Cylinder shaft 311 Cylinder shaft main body 312 Small-diameter cylinder portion 32 Electric heating element 40 Fixing roller (second roller) 41 Fixing roller core 42 Elastic layer 43 Shaft cylinder 50 Fixing belt (endless belt) 51 Side edge portion 511 Back side corner portion 60 Pressure Roller 61 Pressure Roller Main Body 62 Elastic Body Layer 63 Synthetic Resin Film 64 Shaft Cylinder 65 Ring 70 Member 71 Thermal Insulation Bush (Cylinder Body) 711 Cut Groove (Slit)
72 Stop flange (flange, annular flange)
721 inner flange 73 annular curved surface (curved curved surface)
731 R surface 80 housing 801 connecting rod 802 head 803 annular groove 804 coil spring 805 C ring 81 fixing belt side housing 82 side plate 821 square hole 821a guide rail 822 bearing mounting hole 823 bracket 823a locking groove 824 protruding plate 83 Movable plate 831 Bearing mounting hole 832 Coil spring 835 Supporting piece 84 Installation plate 85 U-shaped cover body 851 Rear plate 852 Top plate 853 Bottom plate 854 Through hole 86 Terminal block member 861 Mounting plate 861a Circular hole 862 Terminal block 862a Terminal piece 881 Bearing Mounting hole 87 Pressure roller side housing 88 Side plate 89 Bottom plate 891 Long rectangular hole 892 Screw hole 90 Front plate 91 Inclined top plate 911 Notch 912 Support piece B Bearing N Nip part P Paper P1 Paper bundle S Screw S1 Closed posture S2 Open posture

Claims (3)

First and second rollers rotatable about an axis;
An endless belt wound between the first and second rollers;
A belt detent member disposed at at least one end of the first and / or second roller,
The belt detent member includes a cylindrical body portion having an inner diameter substantially equal to the outer diameter of the first roller or the second roller, and an outer peripheral surface of the first or second roller provided on one end side of the cylindrical body portion. Having a protruding annular flange,
The cylindrical body portion is externally fitted to an end portion of the first or second roller,
The annular flange portion has a wall surface facing a side edge portion of the endless belt in a direction away from the side edge portion from a rising portion from the first or second roller toward a protruding end of the flange portion. A curved surface , wherein the rising portion is close to vertical and the degree of curvature gradually increases, and the side edge of the endless belt is in line contact with the curved surface ,
The cylindrical body portion and the annular flange portion of the stopper member are provided with slits extending in the axial direction of the first or second roller, and opposite ends on the wall surface side of the slit. A round belt device , wherein each corner of the edge in the direction toward the cylinder center is formed with an R surface in a state where each corner is scraped off in a region corresponding to the rising portion . A fixing device for performing a fixing process by heating on a sheet on which a toner image is transferred,
A heating roller with a built-in heat source, a fixing roller arranged to face the heating roller, a fixing belt wound around the fixing roller and the heating roller, and arranged to face the fixing roller via the fixing belt. A pressure roller,
The fixing device according to claim 1 , wherein the heating roller, the fixing roller, and the fixing belt are a first roller, a second roller, and an endless belt in the circulating belt device according to claim 1 . An image forming unit that performs a predetermined image forming process based on the image information and transfers a toner image to paper;
An image forming apparatus comprising: the fixing device according to claim 2 , wherein the toner image transferred to the sheet by the image forming unit is subjected to a fixing process on the sheet.

Images