JP3845733B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus.

  2. Description of the Related Art Conventionally, in an electrophotographic image forming apparatus such as a copying machine or a printer, in order to fix a toner image transferred from a photoconductor to a transfer sheet, the transfer sheet is conveyed while being sandwiched between a heat roller and a pressure roller. However, there is a printer equipped with a fixing device that applies heat and pressure to the transfer paper during the conveyance process.

  As an example of such a fixing device, one shown in FIG. 11 is known. In the fixing device shown in FIG. 11, an elastic piece 103 having a claw-shaped stopper 102 at the upper end is integrally formed on a half-moon bearing 101 that rotatably supports both ends of the heat generating roller 100, and the stopper 102 is formed. The bearing 101 is fixed to the support member 104 by being elastically locked to the support member 104 such as a housing, and then the heating roller 100 is fitted to the bearing 101 while elastically increasing the distance between both ends of the bearing 101. A pressure roller 105 is brought into pressure contact with the heat generating roller 100.

  Then, the bearing 101 is first assembled to the support member 104, and then the heat generating roller 100 is fitted to the bearing 101, and this fitting operation is performed from a direction orthogonal to the axial direction of the heat generating roller 100. The purpose is to facilitate and automate the assembly work.

  Further, in a fixing device having a heat generating roller and a pressure roller, a heater is generally disposed inside the heat generating roller, and these heat generating roller and pressure roller are generally housed in a housing. The heater has a quartz glass tube sealed at both ends, a heating wire provided in the quartz glass tube, a lead wire having one end connected to the heating wire via a metal foil and the other end extending outside the quartz glass tube. Etc. A heater terminal is connected to the other end of the lead wire extending outside the quartz glass tube, and the heater terminal is screwed to the housing. A wire harness for power feeding is connected to the heater terminal.

  The housing of the fixing device that generates high heat is made of a synthetic resin containing glass because it has excellent heat resistance and requires rigidity. On the other hand, bearings also tend to be formed of synthetic resin for the purpose of cost reduction, weight reduction, etc., but the bearings that support the heat generating rollers in the fixing device are excellent in heat resistance and increase rigidity such as PPS. It is necessary to form with expensive synthetic resin. In addition, since the heat generating roller is charged with static electricity due to friction with the transfer paper, the heat generating roller is formed of a conductive material such as a metal material, and the static electricity of the heat generating roller flows to the ground through the conductive bearing. In addition, since the conductive material must be provided with a conductive property, the material used is further expensive.

  From this point of view, when the bearing 101 shown in FIG. 11 is viewed, in order to attach and detach the bearing 101 to and from the support member 104, the elastic piece 103 must be flexibly bent. The length of becomes longer. As a result, the amount of material required to form one bearing 101 increases and the manufacturing cost increases.

  In addition, a large amount of heat is generated from the heater during image forming work, and the heat causes the housing to expand. Then, the heater terminal fixed to the housing moves in a direction away from the heater with this thermal expansion, and a pulling force acts on the lead wire connected to the heater terminal with the movement of the heater terminal, The connection between the heater terminal and the lead wire is disconnected, the connection between the metal foil provided in the quartz glass tube and the lead wire is disconnected, the quartz glass tube is broken, and the heater is damaged.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device and an image forming apparatus capable of facilitating an assembly structure for a bearing housing that supports a heat generating roller and further reducing the material cost of the bearing.

  Another object of the present invention is that the housing thermally expands due to heat during the image forming operation, and the heater terminal fixed to the housing moves in a direction away from the heater along with the thermal expansion, and pulls on the lead wire. Even if the operation of the heater, the connection between the heater terminal and the lead wire is disconnected, the connection between the metal foil and the lead wire provided in the quartz glass tube is disconnected, or the quartz glass tube is broken. It is an object of the present invention to provide a fixing device and an image forming apparatus that can prevent damage to the image forming apparatus.

  The fixing device according to the first aspect of the present invention includes a heat-generating roller that is supported by a bearing and has a sliding surface that is formed of a conductive material and that can be driven. A C-shaped ring formed of a pressure roller and a synthetic resin having elasticity and conductivity, and rotatably supporting the outer periphery of the opposite side of the pressure roller at both ends of the heat generation roller within a range exceeding 180 °. And a bearing that protrudes in the opposite direction of the pressure roller from an intermediate portion of the outer peripheral surface of the ring-shaped portion, and the interval between both ends of the ring-shaped portion can be elastically expanded. A housing that includes an insertion portion in which the protrusion of the bearing is detachably inserted from the pressure roller side and covers the periphery of the heat generating roller and the pressure roller; and the ring-shaped portion of the bearing. Removably locked Having a ground plate attached to the housing and a grounding piece which is grounded to the elastic piece and the ground that.

  Therefore, the movement of the bearing in the circumferential direction is restricted by inserting the protrusion into the insertion portion of the housing, and the bearing is locked by the elastic piece of the ground plate in this state.

  According to a second aspect of the present invention, there is provided a fixing device comprising: a heat-generating roller that can be driven to rotate; a pressure roller that is pressed against the heat-generating roller and rotated following the heat-generating roller; and an elastic synthetic resin; A C-shaped ring-shaped portion that rotatably supports the outer periphery on the opposite side of the pressure roller in a range exceeding 180 °, and protrudes in the opposite direction of the pressure roller from an intermediate portion of the outer peripheral surface of the ring-shaped portion. And a ring in which an interval between both ends of the ring-shaped portion can be elastically expanded, an insertion portion in which the protrusion of the bearing is removably inserted from the pressure roller side, and the ring And a housing that covers the periphery of the heat-generating roller and the pressure roller.

  Therefore, the bearing is restricted from moving in the circumferential direction by inserting the protrusion into the insertion portion of the housing, and is locked by the locking claw of the housing in that state.

  According to a third aspect of the present invention, in the fixing device according to the second aspect, the protrusion of the bearing is formed at a distance of 90 ° or more in the circumferential direction with respect to the locking claw that locks the ring-shaped portion. ing.

  Therefore, if the distance between the protrusion of the bearing and the locking claw that locks the ring-shaped part is 90 ° in the circumferential direction, the protrusion can be formed without causing a large stress when the ring-shaped part is bent. It becomes possible to displace the ring-shaped portion as the base portion and to easily engage and disengage with the locking claw.

  According to a fourth aspect of the present invention, there is provided an image forming apparatus for forming a toner image on the surface of a photosensitive member and transferring the toner image onto a transfer sheet and fixing the image.

  Therefore, it is possible to obtain the same effect as that of the first, second or third aspect of the invention.

  According to the fixing device of the first aspect of the present invention, the C-shaped ring-shaped portion that rotatably supports the outer periphery of the heat generating roller on the opposite side of the pressure roller within a range exceeding 180 °, and the ring-shaped portion A protrusion that protrudes in the opposite direction of the pressure roller from the intermediate portion of the outer peripheral surface, and includes a bearing that can elastically expand the distance between both ends of the ring-shaped portion. A housing that has an insertion portion that is removably inserted from the heating roller and covers the periphery of the heat generating roller and the pressure roller, and further includes an elastic piece that removably locks the ring-shaped portion of the bearing. Since the attached earth plate is provided, the circumferential movement of the bearing can be restricted by inserting the protrusion of the bearing into the insertion portion of the housing, and the bearing can be locked by the elastic piece of the earth plate. Therefore, in order to lock the bearing to the housing, it is not necessary to form a long elastic piece having a stop portion as in the prior art, thereby reducing the material cost used for the bearing.

  According to the fixing device of the second aspect of the present invention, the C-shaped ring-shaped portion that rotatably supports the outer periphery of the heat generating roller on the opposite side of the pressure roller within a range exceeding 180 °, and the ring-shaped portion A protrusion that protrudes in the opposite direction of the pressure roller from the intermediate portion of the outer peripheral surface, and includes a bearing that can elastically expand the distance between both ends of the ring-shaped portion. The housing has a housing that covers the periphery of the heat generating roller and the pressure roller with an insertion portion that is removably inserted from the ring and a locking claw that removably locks the ring-shaped portion. By being inserted into the insertion portion, the circumferential movement of the bearing can be restricted and the bearing can be locked by the locking claw of the housing. Moreover, since the ring-shaped part latched by the latching claw can bend flexibly, it is necessary to form a long elastic piece with a stopper as in the prior art in order to latch the bearing to the housing. In this way, the material costs used for the bearing can be saved.

  According to a fixing device of a third aspect of the present invention, in the second aspect of the invention, the protrusion of the bearing is 90 ° or more in the circumferential direction with respect to the locking claw that locks the ring-shaped portion. Since the ring-shaped part is bent, the ring-shaped part is displaced with the protrusion as a base without causing a large stress when the ring-shaped part is bent. Can do.

  According to the image forming apparatus of the invention of claim 4, since the fixing device of claim 1, 2, or 3 is provided, the same effect as that of the invention of claim 1, 2, or 3 can be obtained. .

  A first embodiment of the present invention will be described with reference to FIGS. First, the internal structure of the image forming apparatus will be described with reference to FIG. Reference numeral 1 denotes an apparatus main body of an image forming apparatus having functions such as a copying machine, a printer, and a facsimile machine. An image reading device 2 for reading an image of a document is mounted on the upper portion of the apparatus main body 1, and a process cartridge 3 is provided inside. A sheet transport path 4 for guiding the transfer sheet S is formed below the process cartridge 3.

  The image reading apparatus 2 includes a reading unit 5 that reads a document image, and a document tray 6 on which a document to be supplied to the reading unit 5 is placed. The document tray 6 has a horizontal position A about a fulcrum shaft 7. To a standing position B indicated by a two-dot chain line. The document tray 6 is configured to be stabilized at the horizontal position A and the standing position B by a stopper (not shown).

  The process cartridge 3 is formed by rotatably providing a photoconductor 9 on a photoconductor case 8 formed in a case shape, and arranging and attaching a charging brush roller 10 and a developing unit 11 around the photoconductor 9. ing. A transfer portion 12 facing the outer periphery of the lower portion of the photoconductor 9 is provided on the apparatus main body 1 side. The developing unit 11 is in contact with the photosensitive member 9, a developing case 13 that is detachably attached to the photosensitive member case 8, a rotatable stirrer 14 that stirs the developer stored in the developing case 13, and the photosensitive member 9. A developing roller 15, a supply roller 16 that supplies developer to the developing roller 15, and a blade 17 that contacts the developing roller 15. Further, an optical writing device 18 that forms an electrostatic latent image by scanning a charged portion of the photosensitive member 9 with a laser beam modulated based on an image signal is provided on the upper part of the process cartridge 3.

  In addition, a tray 19 is provided on one side of the apparatus main body 1 to support a document read by the image reading device 2 and support the transfer paper S in an obliquely placed state. Are elastically brought into contact with the paper feed roller 20, the paper feed roller 20 that is rotationally driven, and the pressing plate 21 that is biased in one direction and presses the transfer paper S on the tray 19 against the paper feed roller 20. Thus, a separation pad 22 and a separation roller 23 that prevent the transfer paper S from being double-fed are provided.

  The paper feed roller 20, the separation pad 22, and the separation roller 23 are disposed on the entrance side of the paper conveyance path 4. A bottom path 24 located downstream of the paper feed roller 20 is communicated with the paper transport path 4. Further, a fixing device 25 for fixing the image transferred onto the transfer paper S is disposed on the downstream side of the paper transport path 4.

  Further, the apparatus main body 1 is formed with a paper stacker 26 disposed between the fixing device 25 and the document tray 6. The sheet stacker 26 has a receiving plate 27 that supports the transfer sheet S and is positioned on the lower extension surface of the document tray 6 when the document tray 6 is rotated to the standing position B. Further, in the vicinity of the side surface of the apparatus main body 1 on the side opposite to the tray 19, the transfer paper S discharged from the fixing device 25 is discharged in the horizontal direction, and the paper discharged from the fixing device 25. A reverse paper discharge path 29 that reverses the transfer paper S and leads it to the paper stacker 26 is formed.

  A pair of paper discharge rollers 30 are arranged at the upper and lower portions of the reverse paper discharge path 29, and the transfer paper S is at the branch point between the reverse paper discharge path 29 and the paper discharge port 28. A switching claw 31 for switching the discharge direction is rotatably provided.

  Next, an image reading operation and a printing operation will be described. When reading an image of a document, the document tray 6 is maintained at a horizontal position A as shown by a solid line in FIG. An image of the supplied original is read by the reading unit 5 and is supported on the tray 19 in a leaning state. The image read in this way is transmitted to the outside (use form as a facsimile transmission mode), or the transfer sheet S is fed from the tray 19 and the read image is printed on the transfer sheet S (as a copying machine). Use form). Alternatively, an image transmitted from the outside can be printed on the transfer paper S (use form as a facsimile reception mode).

  In the case of printing, in FIG. 1, the surface of the photoconductor 9 is charged by the charging brush roller 10 in the process of being rotated in the clockwise direction, and optical writing is performed based on the read image of the document or the image received from the outside. An electrostatic latent image is formed on the charged portion of the photoreceptor 9 by the device 18, and the electrostatic latent image is developed by the developing unit 11. This developed image is transferred to the transfer paper S fed from the tray 19 by the paper feed roller 20. The transfer sheet S on which the image has been transferred is fixed when passing through the fixing device 25, and is discharged to the sheet discharge outlet 28 or the sheet stacker 26 depending on the direction of the switching claw 31.

  Here, the configuration of the fixing device 25 will be described with reference to FIGS. FIG. 2 is a longitudinal side view showing a support structure of a heat generating roller on the front side of the fixing device 25, FIG. 3 is a vertical side view showing a support structure of the heat generating roller on the back side of the fixing device 25, and FIG. FIG. 5 is a side view showing a relationship between the heat generating roller and the bearing.

  The housing 32 of the fixing device 25 is formed by connecting an upper housing 33 and a lower housing 34 with screws 35. A lower portion of the lower housing 34 is fixed to the bottom of the apparatus main body 1 with a screw (not shown).

  The upper housing 33 is provided with bearings 37 that rotatably support both ends of a heat generating roller 36 whose surface is made of metal. These bearings 37 have a semicircular shape for supporting the upper half of the heat generating roller 36 and are formed of a synthetic resin such as PPS. A plurality of ribs 38 for holding the bearing 37 are formed on both sides of the upper housing 33. As shown in FIG. 4, these ribs 38 are opposed to each other so that an insertion portion 39 is formed in the transfer direction of the transfer sheet S (the arrow direction shown in FIGS. 2 and 3), and the heating roller 36. Are arranged opposite to each other so that a gap 40 is formed in the longitudinal direction. A stepped portion 41 is formed at the edge of the rib 38 facing in the transport direction of the transfer sheet S so as to face the insertion portion 39.

  On the other hand, the bearing 37 is formed of a material having heat resistance and a certain degree of elasticity, for example, PPS. This material contains carbon to provide conductivity. The bearing 37 is formed on a C-shaped ring-shaped portion 42 that rotatably supports the upper outer periphery at both ends of the heat generating roller 36 within a range slightly exceeding 180 °, and an outer peripheral surface of the ring-shaped portion 42. A rib 43 and a protrusion 44 projecting upward from an intermediate portion of the rib 43 are provided. The width of the rib 43 is determined so as to fit into the gap 40 of the rib 38 of the upper housing 33. Steps 45 and 46 having a step with respect to the back surface of the ring-shaped portion 42 are formed at both ends of the rib 43, so that the heating roller 36 can be easily inserted into both ends of the inner peripheral surface of the ring-shaped portion 42. An escape recess 47 is formed. The two points P shown in FIG. 5 indicate the end of the range in which the inner peripheral surface of the ring-shaped portion 42 contacts the outer peripheral surface of the heat generating roller 36. The shortest distance between the two points P is the heat generating roller. It is set to a value slightly smaller than the outer diameter of the heat generating roller 36 in a state before the 36 is fitted. That is, in a state where the bearing 37 and the heat generating roller 36 are fitted while elastically expanding both ends of the ring-shaped portion 42 outward, the heat generating roller 36 is slightly tightened by the bearing 37 by its own elasticity. It is configured to prevent the withdrawal. The protrusions 44 are arranged with an angle α (90 °) in the circumferential direction with respect to the step 45 and β (an angle slightly exceeding 90 °) with respect to the step 46.

  Further, an earth plate 48 is provided for flowing static electricity charged on the heat generating roller 36 to the ground via the conductive bearing 37. As shown in FIGS. 3 and 4, the ground plate 48 includes an elastic piece 49 detachably locked to the stepped portion 46 of the bearing 37 and an earth piece 50 grounded to the ground. As shown in FIG. 2, the upper housing 33 is integrally formed with a locking claw 51 that is detachably locked to the stepped portion 45 of the bearing 37.

  As shown in FIGS. 2 and 3, both ends of the pressure roller 52 of the fixing device 25 are supported by the lower housing 34 so as to be movable up and down, and are rotatable by a movable bearing 54 urged upward by a spring 53. It is supported.

  Further, the fixing device 25 according to the present embodiment has a prescribed dielectric strength between a thermal fuse (not shown) and the heat roller 36 when the synthetic resin bearing 37 that supports the heat roller 36 is melted. A heat-resistant stopper 55 is provided that allows the heat generating roller 36 to be displaced in the direction of the thermal fuse (upward) within a range that maintains the insulation interval for obtaining. The stopper 55 is formed of an elastic metal plate, and as shown in FIG. 4, a protrusion that is inserted into the insertion portion 39 between the holding portion 56 that elastically holds the rib 38 of the upper housing 33 and the rib 38. 57. Even if the stopper 55 is in contact with the heat generating roller 36 that is displaced to the temperature fuse side by the pressure contact force of the pressure roller 52 when the bearing 37 is melted, the end of the protruding portion 57 and the stepped portion 41 of the rib 38 are in contact with each other. Therefore, the insulation space between the heat roller 36 and the thermal fuse is maintained.

  In such a configuration, when the fixing device 25 is assembled, the stopper 55 can be assembled to the upper housing 33 only by inserting the protruding portion 57 into the insertion portion 39 between the ribs 38 formed on the upper housing 33. That is, since the clamping part 56 elastically clamps the rib 38, it does not fall off.

  Subsequently, the protruding portion 44 of the bearing 37 is inserted into the insertion portion 39 of the rib 38. As shown in FIG. 33. In this case, since the front side bearing 37 is prevented from moving in the circumferential direction by inserting the protrusion 44 into the insertion portion 39, even when only one step 45 is locked to the locking claw 51. It does not come off from the locking claw 51 and does not come off. Further, although the bearing 37 is formed of a synthetic resin having elasticity, in the case of PPS, since it is relatively hard among the synthetic resins, it cannot be greatly bent. However, since the protrusion 44 is formed 90 degrees apart in the circumferential direction with respect to the locking claw 51 that locks with the end (step 45) of the ring-shaped portion 42, the protrusion 44 is engaged with the locking claw 51. When the ring-shaped portion 42 is bent at the time of stopping, the end (step 45) of the ring-shaped portion 42 is displaced inward with the protrusion 44 as a base without causing a large stress, It becomes possible to make it easy to disengage.

  As shown in FIG. 3, when the rear bearing 37 is attached to the upper housing 33, the bearing 37 is attached to the upper housing 33 by elastically locking the elastic piece 49 of the ground plate 48 with the stepped portion 46. Retained. In this case, since the rear bearing 37 is prevented from moving in the circumferential direction by inserting the protrusion 44 into the insertion portion 39, only one stepped portion 46 is locked to the elastic piece 49 of the ground plate 48. Even if it is in a state of being detached, it will not come off from the elastic piece 49.

  Subsequently, the heat generating roller 36 is fitted to the upper housing 33 by elastically bending the ring-shaped portion 42 of the bearing 37 on the near side and the deep side and fitting the heat generating roller 36 to the bearing 37 while increasing the distance between both ends. Can be assembled. Of course, it is also possible to assemble the bearing 37 into which the heat generating roller 36 is fitted in the upper housing 33 in advance. When the heating roller 36 is fitted to the bearing 37, the ring-shaped portion 42 is bent with a long span in the circumferential direction, so that the shortest distance between the two points P shown in FIG. 5 is slightly smaller than the outer diameter of the heating roller 36. Even if it is expanded to an extent exceeding 1, the large stress will not be generated and the bearing 37 will not be broken.

  Then, the assembly of the fixing device 25 is completed by connecting the upper housing 33 in which the heat generating roller 36 is assembled and the lower housing 34 in which the pressure roller 52 is assembled with the screw 35. In this assembled state, the heat generating roller 36 is pressed upward by the pressure roller 52, and the bearing 37 is pressed by the heat generating roller 36 and is abutted against and fixed to the semicircular lower portion of the rib 38. In this state, the inner peripheral surface of the bearing 37 and the outer peripheral surface of the heat generating roller 36 are maintained in close contact with each other. When the fixing device 25 is disassembled, the operation is performed in the reverse order of the above assembly order.

  As described above, as shown in FIG. 3, when the bearing 37 is assembled on the back side of the upper housing 33, the elastic piece 49 of the ground plate 48 can be bent and the bearing 37 can be held by the elastic piece 49. . As shown in FIG. 2, when the bearing 37 is assembled on the front side of the upper housing 33, the end portion of the ring-shaped portion 42 that can elastically widen the distance between both ends to hold the heat generating roller 36. The locking claw 51 of the upper housing 33 can be locked to the (step 45). Therefore, in either case of FIG. 2 or FIG. 3, in order to lock the bearing 37 to the upper housing 33, it is not necessary to form a long elastic piece having a stopper as in the prior art. As a result, the amount of material used for the bearing 37 is reduced, and material costs can be reduced.

  In this example, the two bearings 37 on the back side and the near side of the housing 32 are used in common.

  Next, a second embodiment of the present invention will be described with reference to FIGS. In addition, the same part as the part demonstrated in FIG. 1 thru | or FIG. 5 is shown with the same code | symbol, and description is also abbreviate | omitted. The basic structure of the image forming apparatus according to the present embodiment is the same as the image forming apparatus described with reference to FIGS. 1 to 5, and the structure of the fixing device 25a is different.

  The fixing device 25a will be described in detail with reference to FIG. The fixing device 25a has a housing 58 fixed to the apparatus main body 1. The housing 58 is formed by connecting an upper housing 59 and a lower housing 60 with screws (not shown). A cylindrical heat generating roller 61 having both ends opened in the lower housing 60 is rotatably supported by a bearing 62, and a pressure roller 63 is rotatably supported by a movable bearing 64 in the upper housing 59. The movable bearing 64 is biased downward by a spring 65, and the outer peripheral surface of the heat generating roller 61 and the outer peripheral surface of the pressure roller 63 are pressed against each other by the biasing force.

  A heater 66 is disposed in the heat generating roller 61. This heater 66 is sealed in a quartz glass tube 67 sealed at both ends, a heating wire 68 provided in the quartz glass tube 67, and sealed in sealing portions at both ends of the quartz glass tube 67, and connected to the heating wire 68. The metal foil 69 has one end connected to the metal foil 69 and the other end formed of lead wires 70 a and 70 b extending to the outside of the quartz glass tube 67.

  One lead wire 70 a is welded with a flat heater terminal 71, and the heater terminal 71 is fastened and fixed to the lower housing 60 by a screw 72. A heater terminal 73 bent in an L shape is welded to the other lead wire 70 b, and the heater terminal 73 is fastened and fixed to the side wall 60 a of the lower housing 60 by a hooked nut 74 and a screw 75. In the portion surrounded by the two sides of the L-shaped bent portion of the heater terminal 73 in the side wall portion 60a, the heater terminal 73 is in the direction of arrow A along the longitudinal direction of the heater 66 with the fixing portion by the screw 75 as a fulcrum (FIG. 3). A flexible space 76 is formed by chamfering, which allows bending to a reference).

  Furthermore, the slit 77 is formed in the L-shaped bending part of the heater terminal 73 (refer FIG. 4). By forming the slit 77, a flexible portion 78 is formed on both sides of the slit 77 in the L-shaped bent portion so that the heater terminal 73 can be bent more easily in the direction of arrow A (see FIG. 4). .

  Plate-shaped conductive members 80 and 81 to which both ends of a thermal fuse 79 are connected are attached to the lower housing 60. One end of the conductive member 80 is fastened and fixed to the lower housing 60 by a screw 72 and is energized with the heater terminal 71. The end of the other conductive member 81 is fastened and fixed to the lower housing 60 by a screw 82. A current-carrying wire harness 83 is connected to the end of the conductive member 81 that is fastened and fixed by the screw 82 and the fastening and fixing portion of the heater terminal 73 by the screw 75.

  In such a configuration, the heater 66 generates heat during the copying operation, and the housing 58 (the upper housing 59 and the lower housing 60) is thermally expanded by this heat, and the housing 58 spreads in the outer circumferential direction due to the thermal expansion. When the lower housing 60 is thermally expanded, the heater terminals 71 and 73 fastened and fixed to the lower housing 60 are moved away from the heater 66. Along with the movement of the heater terminals 71 and 73, a tensile force acts on the lead wires 70a and 70b connected to the heater terminals 71 and 73.

  Here, when the heater terminal 73 moves away from the heater 66 as the lower housing 60 is thermally expanded, a flexible space 76 is formed in the side wall 60a to which the heater terminal 73 is attached. As a result, the heater terminal 73 bends in the direction of arrow A. For this reason, the amount of movement of the heater terminal 73 on the side connected to the lead wire 70b is smaller than the amount of movement of the heater terminal 73 on the side fixed to the side wall 60a, and the tensile force acting on the lead wire 70b is reduced. The power is reduced. Accordingly, damage to the heater 66 due to disconnection of the connection portion between the heater terminal 73 and the lead wire 70b, disconnection of the connection portion between the metal foil 69 and the lead wire 70b, or cracking of the quartz glass tube 67 is prevented. The

  Further, since the flexible portion 78 is formed on the heater terminal 73, the heater terminal 73 is more easily bent in the arrow A direction.

  Although the flat heater terminal 71 connected to the lead wire 70a cannot be bent like the heater terminal 73, the lower housing 60 is thermally expanded and the heater terminal 71 moves away from the heater 66. When the heater terminal 73 is bent, the entire heater 66 moves to the heater terminal 71 side. For this reason, damage to the heater 66 due to disconnection of the connecting portion between the heater terminal 71 and the lead wire 70a, disconnection of the connecting portion between the metal foil 69 and the lead wire 70a, or cracking of the quartz glass tube 67 is prevented. Is done.

  In the present embodiment, the case where the slit 77 is formed in the heater terminal 73 and the flexible portion 78 is formed on both sides of the slit 77 has been described as an example. However, the width of the heater terminal 73 is described. Cutout portions may be formed on both sides in the direction, and a flexible portion having a reduced lateral width may be formed between the cutout portions.

  Next, a third embodiment of the present invention will be described with reference to FIG. In addition, the same part as the part demonstrated in FIG. 6 thru | or FIG. 9 is shown with the same code | symbol, and description is also abbreviate | omitted. In the present embodiment, when the heater terminal 73 is fastened and fixed to the side wall 60a, one side of the heater terminal 73 bent in an L shape is separated from the upper end surface of the side wall 60a, A flexible space 84 is formed between the heater terminal 73 and the heater terminal 73 that allows the heater terminal 73 to bend in the direction of the arrow A along the longitudinal direction of the heater 66 with the fixing portion by the screw 75 as a fulcrum.

  Also in the present embodiment, when the heater terminal 73 moves away from the heater 66 as the lower housing 60 is thermally expanded, the upper portion of the side wall portion 60a to which the heater terminal 73 is attached is allowed. By forming the bending space 84, the heater terminal 73 is bent in the arrow A direction. For this reason, the amount of movement of the heater terminal 73 on the side connected to the lead wire 70b is smaller than the amount of movement of the heater terminal 73 on the side fixed to the side wall 60a, and the tensile force acting on the lead wire 70b is reduced. The power is reduced. Accordingly, damage to the heater 66 due to disconnection of the connection portion between the heater terminal 73 and the lead wire 70b, disconnection of the connection portion between the metal foil 69 and the lead wire 70b, or cracking of the quartz glass tube 67 is prevented. The

1 is a longitudinal side view showing a schematic structure of an image forming apparatus according to a first embodiment of the present invention. FIG. 4 is a longitudinal side view illustrating a support structure of a heat roller on the front side of the fixing device. FIG. 4 is a longitudinal side view showing a support structure of a heat generating roller on the back side of the fixing device. It is a disassembled perspective view which shows the support structure of the bearing which supports the heat-generating roller of a back side. It is a side view which shows the relationship between a heat generating roller and a bearing. It is a vertical side view which shows schematic structure of the image forming apparatus in 2nd embodiment of this invention. It is a longitudinal front view showing the structure of the fixing device. It is a vertical front view which shows the attachment structure to the lower housing of a heater terminal. It is a perspective view which shows a heater terminal. It is a vertical front view which shows the attachment structure to the lower housing of the heater terminal in 3rd embodiment of this invention. It is a side view which shows the support structure of the conventional heat_generation | fever roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 9 Photoconductor 12 Transfer part 15 Developing part 18 Optical writing device 25, 25a Fixing device 32, 58 Housing 36, 61 Heating roller 37 Bearing 39 Insertion part 42 Ring-shaped part 44 Projection part 48 Ground plate 49 Elastic piece 50 Ground piece 51 Locking claws 52, 63 Pressure roller 66 Heaters 70a, 70b Lead wires 71, 73 Heater terminals 76, 84 Flexible space 78 Flexible portion S Transfer paper

Claims (4)

A heat-generating roller that is supported by a bearing and that can be driven to rotate, the sliding surface of which is formed of a conductive material;
A pressure roller that is pressed against the heat generating roller and rotates following the roller;
A C-shaped ring-shaped portion that is formed of a synthetic resin having elasticity and conductivity, and that rotatably supports the outer circumference of the opposite side of the pressure roller at both ends of the heat generation roller within a range exceeding 180 °; A protrusion protruding in the opposite direction of the pressure roller from an intermediate portion of the outer peripheral surface of the ring-shaped portion, and the bearing capable of elastically expanding the distance between both ends of the ring-shaped portion;
A housing that has an insertion portion in which the protrusion of the bearing is removably inserted from the pressure roller side and covers the periphery of the heat generating roller and the pressure roller;
An earth plate attached to the housing having an elastic piece for detachably locking the ring-shaped portion of the bearing and an earth piece grounded to the ground;
A fixing device. A heat generating roller that can be rotated;
A pressure roller that is pressed against the heat generating roller and rotates following the roller;
A C-shaped ring-shaped portion that is formed of an elastic synthetic resin and rotatably supports the outer periphery of the opposite side of the pressure roller at both ends of the heat-generating roller within a range exceeding 180 °, and the ring-shaped portion A protrusion protruding in an opposite direction of the pressure roller from an intermediate portion of the outer peripheral surface of the bearing, and a bearing capable of elastically expanding a distance between both ends of the ring-shaped portion,
The heat generating roller and the pressure roller having an insertion portion in which the protrusion of the bearing is detachably inserted from the pressure roller side and a locking claw for releasably locking the ring-shaped portion. A housing covering the periphery of
A fixing device. The fixing device according to claim 2, wherein the protrusion of the bearing is formed at a distance of 90 ° or more in the circumferential direction with respect to the locking claw that locks the ring-shaped portion. In an image forming apparatus that creates a toner image on the surface of a photoconductor, transfers the toner image onto a transfer sheet, and fixes the toner image,
An image forming apparatus comprising the fixing device according to claim 1.

Images