JP2015194632A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the temperature rise performance of a fixing belt by suppressing the escape of the heat of a reflection member to a support member.SOLUTION: A fixing device includes a fixing belt 22, a pressure member 23 which comes into press-contact with the fixing belt 22, to form a fixing nip 52, a heat source 24 which is arranged inside in the radial direction of the fixing belt 22 and radiates radiation heat, a reflection member 25 which reflects the radiation heat radiated from the heat source 24 toward the inner peripheral surface of the fixing belt 22, a pressing member 27 which presses the fixing belt 22 toward the side of the pressure member 23, a support member 26 which supports the pressing member 27, and a holding member 28 which holds the reflection member 25 and the support member 26. The support member 26 does not come into contact with the reflection member 25. The holding member 28 includes an insertion hole 91 into which the reflection member 25 can be inserted. At least, a gap G is partially formed between the lower surface of the reflection member 25 and the bottom part of the insertion hole 91.

Description

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

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine, a printer, a fax machine, or a multifunction machine includes a fixing device that fixes a toner image on a recording medium such as paper. A heat roller system is widely used for this fixing device. The hot roller method is a method of forming a fixing nip using a pair of rollers.

  On the other hand, in order to reduce the heat capacity of the fixing device and shorten the warm-up time, the fixing method has been shifted from the heat roller method to the belt method. The belt method is a method of forming a fixing nip using a fixing belt.

  For example, in Patent Document 1, a fixing belt, a pressure member that presses against the fixing belt to form a fixing nip (see “Pressure Roller 22” in Patent Document 1), and a radially inner side of the fixing belt are arranged. A heat source (see “Halogen heater 23” in Patent Document 1), a reflective member that reflects radiant heat from the heat source, and a pressing member that presses the fixing belt toward the pressure member side (“Nip forming member in Patent Document 1”). 24 ”) and a support member that supports the pressing member (see“ stay 25 ”of Patent Document 1).

JP 2013-145288 A

  In Patent Document 1, the reflecting member is fixed to the support member. Therefore, when the reflecting member is heated to high temperature due to radiant heat from the heat source, the heat of the reflecting member escapes to the support member, and the heat loss increases. As a result, the temperature raising performance of the fixing belt may be reduced.

  In view of the above circumstances, an object of the present invention is to suppress the heat of a reflecting member from escaping to a support member and to improve the temperature rise performance of a fixing belt.

  The fixing device according to the present invention includes a fixing belt that is rotatably provided around a rotation shaft, a pressure member that is pressed against the fixing belt to form a fixing nip, and is rotatably provided, and a radial direction of the fixing belt A heat source that is disposed on the inside and radiates radiant heat, a reflecting member that reflects radiant heat radiated from the heat source toward the inner peripheral surface of the fixing belt, and presses the fixing belt toward the pressure member. A pressing member, a supporting member that supports the pressing member, and a holding member that holds the reflecting member and the supporting member, and the supporting member covers the entire area in the rotational axis direction with respect to the reflecting member. The holding member is provided with an insertion hole into which the reflection member can be inserted, and a gap is formed at least partially between the lower surface of the reflection member and the bottom of the insertion hole. Features To.

  By adopting such a configuration, it is possible to prevent the heat of the reflection member from escaping to the support member when the reflection member is heated to high temperature due to radiant heat from the heat source. Along with this, heat loss can be reduced, and the temperature raising performance of the fixing belt can be improved.

  The bottom of the insertion hole may be provided with a protrusion on which the reflection member can be placed.

  By adopting such a configuration, a gap can be formed between the lower surface of the reflecting member and the bottom of the insertion hole using a simple configuration.

  The protrusion may be reduced in width from the lower end side toward the upper end side.

  By adopting such a configuration, it is possible to reduce the contact area between the reflecting member and the protrusion. In connection with this, it becomes possible to suppress more effectively that the heat of a reflective member escapes to a support member.

  The reflection member is provided on the downstream side in the recording medium conveyance direction with respect to the first reflection portion inclined toward the fixing nip side toward the upstream side in the conveyance direction of the recording medium. A second reflecting portion that is inclined toward the fixing nip side toward the downstream side in the direction, a third reflecting portion that is provided along the recording medium conveyance direction and connects the first reflecting portion and the second reflecting portion; An extension part extending toward the outer side in the rotation axis direction from the third reflection part, and the extension part may be inserted into the insertion hole and placed on the projection part. .

  By providing the third reflecting portion on the reflecting member as described above, the distance between the heat source and the reflecting member can be easily increased, so that the temperature rise of the reflecting member can be suppressed. Along with this, the life of the reflecting member can be extended. Moreover, it becomes possible to improve the stability of the attitude | position of a reflection member because an extension part is mounted in a projection part.

  The reflection member is provided on the downstream side in the recording medium conveyance direction with respect to the first reflection portion inclined toward the fixing nip side toward the upstream side in the conveyance direction of the recording medium. A second reflecting portion that inclines toward the fixing nip toward the downstream side in the direction, and a lower edge portion of the first reflecting portion and the second reflecting portion is in contact with the bottom portion of the insertion hole. Also good.

  By adopting such a configuration, a gap can be formed between the lower surface of the reflecting member and the bottom of the insertion hole using a simple configuration.

  The holding member may further include another insertion hole into which the support member can be inserted.

  By adopting such a configuration, the support member can be easily assembled to the holding member.

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

  According to the present invention, it is possible to suppress the heat of the reflecting member from escaping to the support member, and to improve the temperature raising performance of the fixing belt.

1 is a schematic diagram illustrating an outline of a printer according to an embodiment of the present invention. 1 is a cross-sectional view illustrating a fixing device according to an embodiment of the present invention. 1 is a cross-sectional view showing a fixing belt and its peripheral portion in a fixing device according to an embodiment of the present invention. FIG. 3 is a side view showing a reflecting member, a supporting member, and a holding member in the fixing device according to the embodiment of the present invention. FIG. 3 is a front view showing a reflecting member, a supporting member, and a holding member in the fixing device according to the embodiment of the present invention. FIG. 9 is a front view showing a reflecting member, a supporting member, and a holding member in a fixing device according to another embodiment of the present invention. FIG. 9 is a front view showing a reflecting member, a supporting member, and a holding member in a fixing device according to another embodiment of the present invention. FIG. 9 is a front view showing a reflecting member, a supporting member, and a holding member in a fixing device according to another embodiment of the present invention.

  First, the overall configuration of the printer 1 (image forming apparatus) will be described with reference to FIG.

  The printer 1 includes a box-shaped printer main body 2, and a paper feed cassette 3 that stores paper (recording medium) is accommodated in a lower portion of the printer main body 2. A paper discharge tray is disposed on the upper surface of the printer main body 2. 4 is provided. An upper cover 5 is attached to the upper surface of the printer main body 2 so as to be openable and closable on the side of the paper discharge tray 4, and a toner container 6 is accommodated below the upper cover 5.

  An exposure unit 7 composed of a laser scanning unit (LSU) is disposed below the paper discharge tray 4 above the printer body 2, and an image forming unit 8 is provided below the exposure unit 7. Yes. The image forming unit 8 is rotatably provided with a photosensitive drum 10 as an image carrier. Around the photosensitive drum 10, a charger 11, a developing device 12, a transfer roller 13, and a cleaning device are provided. The apparatus 14 is disposed along the rotation direction of the photosensitive drum 10 (see arrow X in FIG. 1).

  A paper transport path 15 is provided inside the printer main body 2. A paper feed unit 16 is provided at the upstream end of the conveyance path 15, and a transfer unit 17 configured by the photosensitive drum 10 and the transfer roller 13 is provided at a middle portion of the conveyance path 15. Is provided with a fixing device 18, and a paper discharge unit 19 is provided at the downstream end of the conveyance path 15. A reverse path 20 for double-sided printing is formed below the transport path 15.

  Next, an image forming operation of the printer 1 having such a configuration will be described.

  When the printer 1 is turned on, various parameters are initialized, and initial setting such as temperature setting of the fixing device 18 is executed. Then, when image data is input from a computer or the like connected to the printer 1 and an instruction to start printing is given, an image forming operation is executed as follows.

  First, after the surface of the photosensitive drum 10 is charged by the charger 11, exposure corresponding to the image data is performed on the photosensitive drum 10 by laser light from the exposure device 7 (see the two-dot chain line P in FIG. 1). The electrostatic latent image is formed on the surface of the photosensitive drum 10. Next, the electrostatic latent image is developed by the developing device 12 into a toner image with toner.

  On the other hand, the sheet taken out from the sheet cassette 3 by the sheet feeding unit 16 is conveyed to the transfer unit 17 in synchronization with the above-described image forming operation, and the toner image on the photosensitive drum 10 is transferred to the sheet by the transfer unit 17. Is transcribed. The sheet on which the toner image has been transferred is conveyed downstream in the conveyance path 15 and enters the fixing device 18 where the toner image is fixed on the sheet. The paper on which the toner image is fixed is discharged from the paper discharge unit 19 to the paper discharge tray 4. The toner remaining on the photosensitive drum 10 is collected by the cleaning device 14.

  Next, the fixing device 18 will be described in detail. Hereinafter, for convenience of explanation, the front side of the sheet in FIG. 2 is defined as the front side (front side) of the fixing device 18. An arrow Y in FIG. 2 indicates the sheet conveyance direction (in this embodiment, the left-right direction). An arrow Fr attached to FIG. 4 indicates the front side (front side) of the fixing device 18. The arrow I attached | subjected to FIG. 4 has shown the front-back direction inner side, and the arrow O attached | subjected to FIG. 4 has shown the front-back direction outer side.

  As shown in FIG. 2 and the like, the fixing device 18 includes a box-shaped fixing frame 21, a fixing belt 22 accommodated in the upper part of the fixing frame 21, and a pressure roller 23 accommodated in the lower part of the fixing frame 21. (Pressure member), a heater 24 (heat source) disposed radially inside the fixing belt 22, a reflecting member 25 disposed below the heater 24 on the radially inner side of the fixing belt 22, and the fixing belt 22 The support member 26 disposed below the reflecting member 25 on the radially inner side, the pressing member 27 disposed below the support member 26 on the radially inner side of the fixing belt 22, the reflecting member 25 and the supporting member 26. Holding members 28 (only the holding member 28 on the rear end side is shown in FIG. 2) disposed on the front end side and the rear end side.

  The fixing frame 21 is formed of sheet metal. The fixing frame 21 includes an upper frame portion 31 and a lower frame portion 32 that are connected to each other.

  A belt mounting base 36 is provided on the upper frame portion 31. The belt mount 36 is provided with an arc-shaped belt support portion 37. An annular meandering control ring 38 is provided on the outer periphery of the belt support portion 37. A first thermistor 40 is fixed to the upper frame portion 31. The first thermistor 40 is in contact with the outer peripheral surface of the fixing belt 22.

  The lower frame portion 32 is provided with a swing frame 43. A support shaft 44 is provided on the right end side of the swing frame 43, and the swing frame 43 swings around the support shaft 44 as a fulcrum. A second thermistor 47 is fixed to the lower frame portion 32. The second thermistor 47 is in contact with the outer peripheral surface of the pressure roller 23. The lower frame portion 32 is provided with an entry guide 48 and a discharge guide 49.

  The fixing belt 22 has a substantially cylindrical shape that is long in the front-rear direction. The fixing belt 22 has flexibility and is endless in the circumferential direction. The fixing belt 22 has a diameter of 30 mm, for example.

  The fixing belt 22 includes, for example, a base material layer, an elastic layer provided around the base material layer, and a release layer that covers the elastic layer. The base material layer of the fixing belt 22 is formed of a metal such as SUS having a thickness of 30 μm, for example. The base material layer of the fixing belt 22 may be formed of a resin such as PI (polyimide). The elastic layer of the fixing belt 22 is made of, for example, silicon rubber having a thickness of 270 μm. The release layer of the fixing belt 22 is formed of, for example, a PFA tube having a thickness of 30 μm. In each figure, each layer (base material layer, elastic layer, release layer) of the fixing belt 22 is displayed without being particularly distinguished. A black coating for increasing the heat absorption rate is applied to the inner peripheral surface of the fixing belt 22.

  At both front and rear ends of the fixing belt 22, belt support portions 37 provided on the belt mounting base 36 of the upper frame portion 31 are inserted. As a result, the fixing belt 22 is rotatably supported by the upper frame portion 31. The fixing belt 22 is rotatable about a rotation axis A extending in the front-rear direction. That is, in the present embodiment, the front-rear direction is the rotation axis direction of the fixing belt 22. Both front and rear end surfaces of the fixing belt 22 are disposed on the inner side in the front-rear direction of a meandering restriction ring 38 provided on the belt mount 36 of the upper frame portion 31. As a result, the meandering (moving outward in the front-rear direction) of the fixing belt 22 is restricted.

  The pressure roller 23 has a substantially cylindrical shape that is long in the front-rear direction. The pressure roller 23 has a diameter of 25 mm, for example.

  The pressure roller 23 includes, for example, a cylindrical core member 50, an elastic layer 51 provided around the core member 50, and a release layer (not shown) that covers the elastic layer 51. ing. The core member 50 of the pressure roller 23 is formed of a metal such as iron having a diameter of 18 mm, for example. The elastic layer 51 of the pressure roller 23 is made of, for example, silicon rubber having a thickness of 3.5 mm. The release layer of the pressure roller 23 is formed by, for example, a PFA tube.

  The pressure roller 23 is disposed on the lower side (outside) of the fixing belt 22. The pressure roller 23 is in pressure contact with the fixing belt 22, and a fixing nip 52 is formed between the fixing belt 22 and the pressure roller 23. The paper conveyance direction is, for example, the conveyance direction when the paper passes through the fixing nip 52. The pressure roller 23 is rotatably supported at the longitudinal center of the swing frame 43 of the fixing frame 21 (in this embodiment, the center in the left-right direction). The swing frame 43 swings around the support shaft 44. By moving, the pressure roller 23 moves up and down, and the pressure of the fixing nip 52 is switched. The pressure roller 23 is connected to a drive source 53 configured by a motor or the like.

  The heater 24 (see FIG. 3 and the like) is composed of, for example, a halogen heater. The heater 24 is disposed in an upper region R1 (region on the side away from the fixing nip 52) in the space S on the radially inner side of the fixing belt 22. The heater 24 generates heat when energized and radiates radiant heat.

  The reflecting member 25 (see FIG. 3 and the like) has a long shape in the front-rear direction. The reflecting member 25 is made of a metal such as bright aluminum, for example. The reflection member 25 is provided so as to partition the heater 24 and the support member 26. The upper surface (surface on the heater 24 side) of the reflection member 25 is a reflection surface (mirror surface) that reflects the radiant heat radiated from the heater 24 toward the inner peripheral surface of the fixing belt 22. The reflection member 25 is disposed so as to cover the upper side (the heater 24 side) of the support member 26.

  The reflecting member 25 includes a first reflecting portion 61, a second reflecting portion 62 provided on the left side of the first reflecting portion 61 (downstream side in the paper transport direction), the first reflecting portion 61, and the second reflecting portion 62. And a third reflecting portion 63 to be connected.

  The first reflecting portion 61 is inclined downward (fixing nip 52 side) toward the right side (upstream side in the sheet conveyance direction). The second reflecting portion 62 is inclined downward (fixing nip 52 side) toward the left side (downstream side in the sheet conveyance direction). The third reflector 63 is provided along the left-right direction (paper transport direction).

  The reflection member 25 is bent so as to be convex toward the upper side (the heater 24 side). In other words, the reflection member 25 is bent so as to be concave toward the lower side (the support member 26 side). Therefore, a recess 66 is formed below the reflecting member 25 (on the support member 26 side) so as to be surrounded by the first reflecting portion 61, the second reflecting portion 62, and the third reflecting portion 63.

  As shown in FIG. 4, the reflecting member 25 includes a pair of front and rear extending portions 64 that extend outward from the third reflecting portion 63 in the front-rear direction. Each extending portion 64 is provided at both front and rear end portions of the reflecting member 25 and extends outward in the front-rear direction from the first reflecting portion 61 and the second reflecting portion 62.

  The support member 26 (see FIG. 3 and the like) has a long shape in the front-rear direction. The support member 26 is provided with a space from the reflecting member 25. That is, the support member 26 is not in contact with the reflection member 25 over the entire area in the front-rear direction.

  The support member 26 includes an upstream stay 71 and a downstream stay 72. The upstream stay 71 and the downstream stay 72 are formed of sheet metal such as SECC (galvanized steel sheet) having a thickness of 2.0 mm, for example.

  The upstream stay 71 includes an upstream base plate 73 extending in the vertical direction, an upstream support plate 74 bent from the lower end of the upstream base plate 73 toward the right side (upstream side in the sheet conveyance direction), and the upstream side. And an upstream guide plate 75 bent upward from the right end portion of the support plate 74.

  The downstream stay 72 includes a downstream base plate 80 extending in the vertical direction, a downstream support plate 81 bent from the lower end of the downstream base plate 80 toward the left side (downstream in the sheet transport direction), and the downstream side. And a downstream guide plate 82 bent upward from the left end portion of the support plate 81. The downstream base plate 80 is fixed to the upstream base plate 73 by screws 84.

  As shown in FIG. 4, the upstream guide plate 75 and the downstream guide plate 82 (not shown in FIG. 4) include a pair of front and rear extension plates 83. Each extension plate 83 extends outward in the front-rear direction from the base plates 73 and 80 and the support plates 74 and 81. The pressing member 27 (see FIG. 3 and the like) has a plate shape that is long in the front-rear direction. The pressing member 27 is made of, for example, a metal such as aluminum or a heat resistant resin such as LCP (Liquid Crystal Polymer).

  The upper surface of the pressing member 27 is in contact with the lower surface of the support member 26 (specifically, the lower surface of the upstream support plate 74 of the upstream stay 71 and the lower surface of the downstream support plate 81 of the downstream stay 72). Accordingly, the pressing member 27 is supported by the support member 26, and warping (deformation due to the fixing load) of the pressing member 27 is suppressed.

  The lower surface of the pressing member 27 is inclined downward (on the pressure roller 23 side) from the right side (upstream side in the paper transport direction) toward the left side (downstream side in the paper transport direction). The lower surface of the pressing member 27 presses the fixing belt 22 toward the lower side (pressure roller 23 side).

  A sheet member 90 is interposed between the lower surface of the pressing member 27 and the inner peripheral surface of the fixing belt 22. The sheet member 90 is made of, for example, a fluorine resin such as PTFE, and has a lower friction coefficient than the pressing member 27. A lubricant (grease) may be applied between the lower surface of the pressing member 27 and the inner peripheral surface of the fixing belt 22.

  Each holding member 28 (see FIGS. 4 and 5 etc.) has a horizontally long rectangular shape when viewed from the front. An upper insertion hole 91 (insertion hole) is provided in the center of each holding member 28 in the left-right direction. The upper insertion hole 91 has a horizontally long rectangular shape. The extending portion 64 of the reflecting member 25 is inserted into the upper insertion hole 91.

  A pair of left and right projections 92 are provided on the bottom 91 a of the upper insertion hole 91. Each protrusion 92 is formed with the same width from the lower end side to the upper end side. On each protrusion 92, the extending portion 64 of the reflecting member 25 is placed. With such a configuration, the reflecting member 25 is held by each holding member 28, and a gap G is formed between the lower surface 64 a of the extending portion 64 of the reflecting member 25 and the bottom portion 91 a of the upper insertion hole 91.

  Lower insertion holes 93 (other insertion holes) are provided on the left and right sides of the lower portion of each holding member 28. Each lower insertion hole 93 has a vertically long rectangular shape. Each extension plate 83 of the support member 26 is inserted into each lower insertion hole 93. With such a configuration, the support member 26 is held by each holding member 28. 4 and 5, the extension plates 83 of the support member 26 are in contact with the upper surface rather than the lower surface of the lower insertion holes 93 because the support member 26 is added as the fixing nip 52 is formed. This is because it is pressed upward by the pressure roller 23.

  In the fixing device 18 configured as described above, when the toner image is fixed on the paper, the driving source 53 is driven. When the drive source 53 is driven in this way, the rotation of the drive source 53 is transmitted to the pressure roller 23, and the pressure roller 23 rotates as indicated by an arrow B in FIG. When the pressure roller 23 rotates in this way, as indicated by an arrow C in FIG. 2, the fixing belt 22 that is in pressure contact with the pressure roller 23 is driven to rotate in the direction opposite to the pressure roller 23. When the fixing belt 22 rotates in this way, the fixing belt 22 slides with respect to the pressing member 27 and the sheet member 90.

  Further, when fixing the toner image on the paper, the heater 24 is operated (lighted). When the heater 24 is operated in this way, radiant heat is radiated from the heater 24. A part of the radiant heat radiated from the heater 24 is directly irradiated onto and absorbed by the inner peripheral surface of the fixing belt 22 as indicated by an arrow D in FIG. Further, another part of the radiant heat radiated from the heater 24 is reflected by the reflecting member 25 toward the inner peripheral surface of the fixing belt 22 as indicated by an arrow E in FIG. Absorbed into the surface. Due to the above operation, the fixing belt 22 is heated by the heater 24. When the paper passes through the fixing nip 52 in this state, the toner image is heated and melted, and the toner image is fixed on the paper.

  In the present embodiment, as described above, the support member 26 is not in contact with the reflection member 25 over the entire area in the front-rear direction, and the lower surface 64a of the extending portion 64 of the reflection member 25 and the upper insertion hole 91 are not contacted. A gap G is formed between the bottom portions 91a. By adopting such a configuration, it is possible to suppress the heat of the reflection member 25 from escaping to the support member 26 when the reflection member 25 is heated to high temperature due to radiant heat from the heater 24. Along with this, heat loss can be reduced, and the temperature rise performance of the fixing belt 22 can be improved.

  In addition, since the heat of the reflecting member 25 can be prevented from escaping to the support member 26 as described above, the temperature rise of the support member 26 can be suppressed. Along with this, it is possible to suppress the temperature rise of the pressing member 27 supported by the support member 26, and it is possible to improve the durability of the pressing member 27.

  In addition, a pair of left and right protrusions 92 on which the extending portion 64 of the reflecting member 25 can be placed are provided on the bottom 91 a of the upper insertion hole 91. By adopting such a configuration, the gap G can be formed between the lower surface 64a of the extending portion 64 of the reflecting member 25 and the bottom portion 91a of the upper insertion hole 91 using a simple configuration.

  Each protrusion 92 is formed with the same width from the lower end side to the upper end side. By adopting such a configuration, the reflecting member 25 can be stably held by the holding member 28.

  Further, since the third reflecting portion 63 is provided in the reflecting member 25, the distance between the heater 24 and the reflecting member 25 can be easily increased. For this reason, it is possible to suppress the temperature rise of the reflecting member 25 and to extend the life of the reflecting member 25. In addition, since the extending portion 64 of the reflecting member 25 is placed on each projection 92, the posture stability of the reflecting member 25 can be improved.

  Each holding member 28 includes a lower insertion hole 93 into which each extension plate 83 of the support member 26 can be inserted. By adopting such a configuration, the support member 26 can be easily assembled to each holding member 28.

  Further, as shown in FIG. 3 and the like, the heater 24 is arranged in the upper region R1 (region on the side away from the fixing nip 52) in the space S on the radially inner side of the fixing belt 22. By adopting such a configuration, the heater 24 is arranged in the right region R2 (region upstream in the paper transport direction) and the left region R3 (region downstream in the paper transport direction) in the space S. Compared to the case, it is possible to increase the distance between the heater 24 and the supporting member 26 and the pressing member 27 arranged around the fixing nip 52. Along with this, it is possible to suppress the temperature rise of the support member 26 and the pressing member 27.

  In this embodiment, the case where each protrusion 92 was formed with the same width from the lower end side to the upper end side was demonstrated. On the other hand, in other different embodiments, as shown in FIG. 6, each protrusion 92 may be reduced in width from the lower end side toward the upper end side. By adopting such a configuration, it is possible to reduce the contact area between the reflecting member 25 and each projection 92. Along with this, it is possible to more effectively suppress the heat of the reflecting member 25 from escaping to the support member 26.

  In particular, as shown in FIG. 6, the upper end of each projection 92 has a sharp shape (V-shape), so that the reflecting member 25 and each projection 92 are point-like when viewed from the front (viewed in the front-rear direction). Will come into contact. Accordingly, the contact area between the reflecting member 25 and each protrusion 92 can be further reduced, and the heat of the reflecting member 25 can be more effectively suppressed from escaping to the support member 26. Become.

  In the present embodiment, the case where the gap G is formed by placing the extending portion 64 of the reflecting member 25 on each protrusion 92 has been described. On the other hand, in another different embodiment, as shown in FIG. 7, the lower edge portion 61 a of the first reflecting portion 61 and the lower edge portion 62 a of the second reflecting portion 62 of the reflecting member 25 are the bottom portion of the upper insertion hole 91. The gap G may be formed by coming into contact with 91a. By adopting such a configuration, the gap G can be formed using a simple configuration as in the present embodiment.

  In the present embodiment, the case where the upper insertion hole 91 has a horizontally long rectangular shape has been described. On the other hand, in another different embodiment, as shown in FIG. 7, the upper insertion hole 91 may be bent so as to protrude upward corresponding to the reflecting member 25.

  In the present embodiment, the case where the reflecting member 25 includes the first reflecting portion 61, the second reflecting portion 62, and the third reflecting portion 63 has been described. On the other hand, in another different embodiment, as shown in FIG. 8, the reflection member 25 is provided along the vertical direction (direction intersecting (orthogonal) with the sheet conveyance direction) and on the right side of the support member 26. The first plate unit 101 disposed on the upstream side of the paper conveyance direction and the vertical direction (direction intersecting (orthogonal to) the paper conveyance direction) and the left side of the support member 26 (paper conveyance) A second plate portion 102 disposed on the downstream side in the direction, and a third plate portion 103 that connects the first plate portion 101 and the upper end portion of the second plate portion 102 (the end portion on the side away from the fixing nip 52). , May be provided. By adopting such a configuration, the reflecting member 25 has a U-shape, and the space formed on the lower side (the supporting member 26 side) of the reflecting member 25 can be increased. Accordingly, the degree of freedom in the layout of the support member 26 can be increased.

  When the reflecting member 25 is U-shaped as described above, the lower edge portion 101a of the first plate portion 101 and the lower edge of the second plate portion 102 of the reflecting member 25 are shown in FIG. The gap G may be formed by the portion 102 a contacting the bottom 91 a of the upper insertion hole 91, or the gap G is formed by placing the reflecting member 25 on the protrusion provided in the upper insertion hole 91. May be.

  In this embodiment, the case where the 1st reflection part 61 and the 2nd reflection part 62 of the reflection member 25 were connected via the 3rd reflection part 63 was demonstrated. On the other hand, in other different embodiment, the 1st reflection part 61 and the 2nd reflection part 62 of the reflection member 25 may be directly connected. By adopting such a configuration, the shape of the reflecting member 25 can be simplified.

  In the present embodiment, the case where the second reflecting portion 62 of the reflecting member 25 is inclined downward (fixing nip 52 side) toward the left side (downstream side in the sheet conveyance direction) has been described. On the other hand, in another different embodiment, the second reflecting portion 62 of the reflecting member 25 may be inclined downward (fixing nip 52 side) toward the right side (upstream side in the sheet conveyance direction).

  In the present embodiment, the case where one heater 24 is arranged on the inner side in the radial direction of the fixing belt 22 has been described. On the other hand, in other different embodiments, a plurality of heaters 24 may be arranged inside the fixing belt 22 in the radial direction.

  In the present embodiment, the case where a halogen heater is used as the heater 24 has been described. However, in another different embodiment, a ceramic heater or the like may be used as the heater 24.

  In this embodiment, the case where the configuration of the present invention is applied to the printer 1 has been described. However, in another different embodiment, the configuration of the present invention is applied to other image forming apparatuses such as a copying machine, a facsimile machine, and a multifunction machine. It is also possible.

1 Printer (image forming device)
18 Fixing Device 22 Fixing Belt 23 Pressure Roller (Pressure Member)
24 Heater (heat source)
25 Reflecting member 26 Supporting member 27 Pressing member 28 Holding member 52 Fixing nip 61 First reflecting portion 61a Lower edge portion (first reflecting portion) 62 Second reflecting portion 62a Lower edge portion (second reflecting portion) 63 Third Reflection part 64 Extension part 64a Lower surface (extension part) 91 Upper insertion hole (insertion hole)
91a Bottom (upper insertion hole) 92 Protrusion 93 Lower insertion hole (other insertion holes)
A (Rotating belt) Rotating shaft G Gap

Claims (7)

A fixing belt provided rotatably around a rotation axis;
A pressure member provided in a rotatable manner to form a fixing nip by pressing against the fixing belt;
A heat source that is disposed radially inside the fixing belt and emits radiant heat;
A reflecting member that reflects radiant heat radiated from the heat source toward an inner peripheral surface of the fixing belt;
A pressing member that presses the fixing belt toward the pressing member;
A support member for supporting the pressing member;
A holding member for holding the reflecting member and the support member,
The support member is non-contact with the reflecting member over the entire region in the rotation axis direction,
The holding member includes an insertion hole into which the reflection member can be inserted, and a fixing device is characterized in that a gap is formed at least partially between the lower surface of the reflection member and the bottom of the insertion hole. .   The fixing device according to claim 1, wherein a projection portion on which the reflecting member can be placed is provided at the bottom portion of the insertion hole.   The fixing device according to claim 2, wherein the protrusion has a reduced width from the lower end side toward the upper end side. The reflective member is
A first reflecting portion that inclines toward the fixing nip toward the upstream side in the conveyance direction of the recording medium;
A second reflecting portion provided on the downstream side in the conveyance direction of the recording medium with respect to the first reflection portion and inclined toward the fixing nip side toward the downstream side in the conveyance direction of the recording medium
A third reflecting portion that is provided along the recording medium conveyance direction and connects the first reflecting portion and the second reflecting portion;
An extending portion extending from the third reflecting portion toward the outer side in the rotation axis direction,
The fixing device according to claim 2, wherein the extension portion is inserted into the insertion hole and is placed on the projection portion. The reflective member is
A first reflecting portion that inclines toward the fixing nip toward the upstream side in the conveyance direction of the recording medium;
A second reflecting portion provided downstream of the first reflecting portion in the recording medium conveyance direction and inclined toward the fixing nip side toward the downstream side of the recording medium conveyance direction,
5. The fixing device according to claim 1, wherein lower edges of the first reflecting portion and the second reflecting portion are in contact with the bottom portion of the insertion hole.   The fixing device according to claim 1, wherein the holding member further includes another insertion hole into which the support member can be inserted.   An image forming apparatus comprising the fixing device according to claim 1.

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