JP6225615B2 - Fixing device - Google Patents

Description

  The present invention relates to a fixing device that thermally fixes a toner image on a sheet.

  Conventionally, as a fixing device, a cylindrical fixing film, a nip plate that is in sliding contact with the inner peripheral surface of the fixing film, a pressure roller that sandwiches the fixing film between the nip plates, and a heater that is disposed inside the fixing film And a stay that supports the nip plate in a state of surrounding the heater (see Patent Document 1).

JP 2008-233886 A

  By the way, in the technique mentioned above, it is also conceivable that a cover member for supporting the electric wire is provided outside the stay so as to cover the stay. However, in this case, if substantially the entire inner surface of the cover member is brought into close contact with the stay, the heat of the heater is transmitted to the cover member through the stay, and the electric wire may be affected by the heat.

  Therefore, an object of the present invention is to suppress the heat of a heater (heating element) from being transmitted to an electric wire via a stay and a cover member.

In order to solve the above problems, a fixing device according to the present invention includes an endless fixing belt, a heating element disposed inside the fixing belt and configured to generate heat, and spaced apart from the heating element. A nip member arranged to receive radiant heat from the heating element, a backup member sandwiching the fixing belt between the nip member, and an inner side of the fixing belt, covering the heating element A stay that supports the nip member, a cover member that is disposed inside the fixing belt, covers the stay from the side opposite to the heating element, and is provided on the opposite side of the stay of the cover member, An electric wire for conducting electricity.
The cover member is disposed on the opposite side of the heat generating body with respect to the stay, the first wall and the second wall facing each other across the heat generating body and the stay, and the first wall and the second wall A third wall connecting the walls, a first rib projecting from the first wall toward the stay and contacting the stay, and a first rib projecting from the second wall toward the stay and contacting the stay. 2 ribs and a third rib protruding from the third wall toward the stay and contacting the stay.

  According to this configuration, each wall and the stay constituting the cover member are spaced apart by the rib provided on each wall, so that a space is formed between each wall and the stay. Since it functions as a heat insulating layer, for example, it is possible to suppress the heat of the stay from being transmitted to the electric wire through each wall of the cover member as compared with a structure in which each wall of the cover member is in close contact with the stay.

  In the above configuration, a plurality of the first ribs may be provided at intervals in the width direction of the fixing belt.

  According to this, the rigidity of the first wall can be improved by the plurality of first ribs.

  Further, in the above-described configuration, the heating element is configured to generate heat with a heat generation amount greater than the predetermined heat generation amount, and a first heat generation portion configured to generate heat with a predetermined heat generation amount or less in the width direction. And the cover member has a first portion corresponding to the first heat generating portion and a second portion corresponding to the second heat generating portion in the width direction. In the case, the number of the first ribs arranged in the range of the unit length in the width direction of the second portion is arranged in the range of the unit length in the width direction of the first portion. The number can be less than the number of the first ribs.

  According to this, since the number of the first ribs provided in the second portion corresponding to the second heat generating portion having the large heat generation amount is small, the second heat generating portion having the large heat generation amount is connected to the first wall via the first rib. The amount of heat transmitted can be kept small.

  In the above-described configuration, the first rib may be cylindrical.

  According to this, the rigidity of the first wall can be improved by the cylindrical first rib.

  In the above-described configuration, when the first wall has an opening for providing a temperature detection member for detecting the temperature of the nip member, the first rib is provided adjacent to the opening. be able to.

  According to this, since the periphery of the opening can be reinforced with the first rib, the rigidity of the first wall can be improved.

  In the above-described configuration, a plurality of the third ribs may be provided extending from one end side in the width direction of the fixing belt toward the other end side and spaced from each other in a direction orthogonal to the width direction.

  According to this, since it becomes possible to flow air in the width direction between the plurality of third ribs, the stay can be efficiently cooled by the air, and the amount of heat transferred from the stay to the cover member can be reduced. Can be suppressed.

  In the above-described configuration, when the cover member has a fourth wall connecting the first wall, the second wall, and the third wall at both ends in the width direction, the fourth wall May have an opening facing the gap between the plurality of third ribs in the width direction.

  According to this, the air heated between the plurality of third ribs is discharged to the outside from one opening, and the air that has not been heated is introduced from the other opening toward the plurality of third ribs. Therefore, the stay can be efficiently cooled, and the amount of heat transferred from the stay to the cover member can be kept small.

  In the above-described configuration, the third rib may be cylindrical.

  According to this, the rigidity of the third wall can be improved by the cylindrical third rib.

  In the above-described configuration, the electric wire is disposed on a surface of the third wall opposite to the surface on which the third rib is provided, and the third rib is in a direction from the backup member toward the nip member. It can be set as the structure arrange | positioned so that it may not overlap with the said electric wire when it projects.

  According to this, it can suppress that the heat transmitted from a heat generating body via a stay and a 3rd rib is transmitted to an electric wire.

  According to the present invention, it is possible to suppress the heat of the heating element from being transmitted to the electric wire via the stay and the cover member.

1 is a diagram illustrating a schematic configuration of a laser printer including a fixing device according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view of a fixing device. It is a perspective view which decomposes | disassembles and shows a heating unit. It is a perspective view which shows the relationship between a cover member and an electric wire. It is the expansion perspective view which looked at the cover member from the lower side. It is the top view which looked at the cover member from the lower side. It is a figure which shows the halogen heater and rib in 2nd Embodiment. It is an expansion perspective view which shows the form which formed the rib in the cylinder shape. They are the perspective view (a) and top view (b) which show the relationship between an electric wire and an upper side rib.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the following description, first, a schematic configuration of the laser printer 1 provided with the fixing device 100 of the present invention will be described, and then a characteristic part of the present invention will be described in detail.

  In the following description, the direction will be described with reference to the user who uses the laser printer 1. That is, the right side in FIG. 1 is “front”, the left side is “rear”, the front side is “left”, and the back side is “right”. Also, the vertical direction in FIG.

<Schematic configuration of laser printer>
As shown in FIG. 1, a laser printer 1 includes a paper feed unit 3 that supplies paper P, an exposure device 4, a process cartridge 5 that transfers a toner image onto the paper P, and paper. It mainly includes a fixing device 100 that thermally fixes a toner image on P.

  The paper feed unit 3 is provided in the lower part of the main body housing 2, and includes a paper feed tray 31 that accommodates the paper P, a paper pressing plate 32 that lifts the front side of the paper P, a paper feed roller 33, and a paper feed pad 34. And paper dust removing rollers 35 and 36 and a registration roller 37 are mainly provided. The paper P in the paper feed tray 31 is brought close to the paper feed roller 33 by the paper pressing plate 32 and separated one by one by the paper feed roller 33 and the paper feed pad 34, and the paper dust removing rollers 35, 36 and the registration roller 37. Then, it is conveyed toward the process cartridge 5.

  The exposure apparatus 4 is arranged at the upper part in the main body housing 2 and mainly includes a laser light emitting unit (not shown), a polygon mirror 41 that is rotationally driven, lenses 42 and 43, and reflecting mirrors 44, 45, and 46. In preparation. In the exposure apparatus 4, the laser light (see the chain line) based on the image data emitted from the laser light emitting part is reflected or passed through the polygon mirror 41, the lens 42, the reflecting mirrors 44 and 45, the lens 43 and the reflecting mirror 46 in this order. The surface of the photosensitive drum 61 is scanned at high speed.

  The process cartridge 5 is disposed below the exposure apparatus 4 and is detachably mounted on the main body housing 2 through an opening formed when the front cover 21 provided on the main body housing 2 is opened. Yes. The process cartridge 5 includes a drum unit 6 and a developing unit 7.

  The drum unit 6 mainly includes a photosensitive drum 61, a charger 62, and a transfer roller 63. The developing unit 7 is configured to be detachably attached to the drum unit 6, and includes a developing roller 71, a supply roller 72, a layer thickness regulating blade 73, and a toner that contains toner (developer). The housing part 74 is mainly provided.

  In the process cartridge 5, the surface of the photosensitive drum 61 is uniformly charged by the charger 62 and then exposed by high-speed scanning of the laser light from the exposure device 4, whereby image data is transferred onto the photosensitive drum 61. An electrostatic latent image based on is formed. Further, the toner in the toner container 74 is supplied to the developing roller 71 via the supply roller 72 and enters between the developing roller 71 and the layer thickness regulating blade 73 to form a thin layer of a certain thickness on the developing roller 71. It is carried on.

  The toner carried on the developing roller 71 is supplied from the developing roller 71 to the electrostatic latent image formed on the photosensitive drum 61. As a result, the electrostatic latent image is visualized and a toner image is formed on the photosensitive drum 61. Thereafter, the paper P is conveyed between the photosensitive drum 61 and the transfer roller 63, whereby the toner image on the photosensitive drum 61 is transferred onto the paper P.

  The fixing device 100 is provided behind the process cartridge 5. The toner image transferred onto the paper P passes through the fixing device 100 and is thermally fixed onto the paper P. The paper P on which the toner image is thermally fixed is discharged onto the paper discharge tray 22 by the transport rollers 23 and 24.

<Detailed configuration of fixing device>
As shown in FIG. 2, the fixing device 100 includes an endless fixing belt 110, a heating unit 200 that is disposed inside the fixing belt 110 and heats the fixing belt 110, and a pressure roller 120 as an example of a backup member. And a temperature detection member 150 and a cover member 130 are mainly provided.

  The fixing belt 110 is a belt having heat resistance and flexibility that is heated by a heating unit 200 described later. The rotation of the fixing belt 110 is guided by a guide member (not shown).

  The pressure roller 120 is an elastically deformable member and is disposed below the fixing belt 110 and a heating unit 200 described later. The pressure roller 120 is elastically deformed to sandwich the fixing belt 110 with the heating unit 200 (nip plate 220), thereby forming a nip portion N. In the present embodiment, the heating unit 200 and the pressure roller 120 are configured to be in pressure contact with each other by being urged toward the other.

  The pressure roller 120 is configured to be driven to rotate by a driving force transmitted from a motor (not shown) provided in the main body housing 2, and to rotate with the fixing belt 110 (or paper P). The fixing belt 110 is driven to rotate by the frictional force. As a result, the sheet P on which the toner image is transferred is conveyed between the pressure roller 120 and the heated fixing belt 110 from the front to the back, whereby the toner image is thermally fixed.

  The heating unit 200 is a unit that heats the toner on the paper P via the fixing belt 110, and includes a halogen lamp 210 as an example of a heating element, a nip plate 220 as an example of a nip member, a reflection plate 230, And a stay 240.

  The halogen lamp 210 is a heating element that heats the toner transferred onto the paper P by heating the nip plate 220 and the fixing belt 110, and has a predetermined interval from the inner peripheral surface of the fixing belt 110 inside the fixing belt 110. Are arranged apart from each other. The halogen lamp 210 mainly has a glass tube 211 that is long in the left-right direction and a filament 212 that is spirally wound and disposed in the glass tube 211, and generates heat inside the fixing belt 110 by energizing the filament 212. Is configured to do.

  The nip plate 220 is a plate-like member that receives radiant heat from the halogen lamp 210, and is arranged inside the fixing belt 110 so that the inner peripheral surface of the cylindrical fixing belt 110 is in sliding contact with the lower surface thereof. In the present embodiment, the nip plate 220 is formed, for example, by processing an aluminum plate or the like having a higher thermal conductivity than a steel stay 240 described later.

  As shown in FIG. 3, the nip plate 220 mainly includes a base portion 221 formed in a plate shape that is long on the left and right sides, and three projecting portions 222 provided at the rear end of the base portion 221.

  The base portion 221 is a portion whose bottom surface is in contact with the inner peripheral surface of the fixing belt 110, and transmits heat from the halogen lamp 210 to the toner on the paper P via the fixing belt 110.

  Two protruding portions 222 are provided near the center of the rear end of the base portion 221 and one at the right end portion, and extend from the rear end of the base portion 221 along the conveyance direction of the paper P and are formed in a substantially flat plate shape. Yes. More specifically, the protrusion 222 extends to the rear of a rear wall 243 of a stay 240 described later and a flange 232 of the reflector 230 (see FIG. 2).

  As shown in FIGS. 2 and 3, the reflector 230 directs radiant heat from the halogen lamp 210 (mainly radiant heat radiated in the front-rear direction and the upward direction) toward the nip plate 220 (the upper surface of the base portion 221). And is disposed at a predetermined interval from the halogen lamp 210 so as to cover the halogen lamp 210.

  By collecting the radiant heat from the halogen lamp 210 onto the nip plate 220 by such a reflector 230, the radiant heat from the halogen lamp 210 can be used efficiently, and the nip plate 220 and the fixing belt 110 can be heated quickly. Can do.

  Specifically, the reflecting plate 230 is formed by bending, for example, an aluminum plate or the like having a large reflectance of infrared rays and far infrared rays and a thermal conductivity larger than that of a stay 240 described later, for example, an aluminum plate. . More specifically, the reflection plate 230 extends from the halogen lamp 210 outward in the front-rear direction from the reflection portion 231 having a curved shape (substantially U-shaped in cross-section) and both ends of the reflection portion 231 on the nip plate 220 side. And a flange portion 232.

  The stay 240 is a member that supports both ends of the nip plate 220 in the front-rear direction from the side opposite to the pressure roller 120 and receives the force when a force is applied to the nip plate 220 from the pressure roller 120 side. is there. The stay 240 has a relatively high rigidity, for example, a metal plate such as a steel plate that has an opening on the nip plate 220 side and bends in a substantially U shape in cross section along the reflection plate 230 (reflection portion 231). It is formed by.

  More specifically, the stay 240 has an upper wall 241 disposed above the halogen lamp 210, and a front wall 242 and a rear wall 243 that extend downward from the front and rear ends of the upper wall 241.

  As shown in FIG. 2, the front wall 242 is located upstream of the halogen lamp 210 in the transport direction of the paper P. The front wall 242 sandwiches the flange 232 on the front side of the reflector 230 with the nip plate 220 at the lower end thereof, and supports the front end of the nip plate 220 (front end of the base portion 221) from above. doing.

  The rear wall 243 is located downstream of the halogen lamp 210 in the transport direction of the paper P. The rear wall 243 sandwiches the flange 232 on the rear side of the reflector 230 with the nip plate 220 at the lower end thereof, and the rear end of the nip plate 220 (the rear end of the base portion 221). Support from above.

  The temperature detection member 150 is, for example, a sensor such as a thermostat or a thermistor. The temperature detection member 150 is provided on the opposite side of the halogen lamp 210 with respect to the rear wall 243 of the stay 240 and detects the temperature of the nip plate 220.

  Specifically, as shown in FIG. 3, one temperature detection member 150 is provided for each protrusion 222 of the nip plate 220 and is disposed so as to contact the upper surface of the protrusion 222. The temperature detection member 150 is configured to detect the temperature of the protrusion 222 and output the detection result to a control device (not shown) for controlling the fixing device 100 (halogen lamp 210).

  As shown in FIGS. 2 and 3, the cover member 130 is disposed inside the fixing belt 110 and is configured to cover the stay 240 from the side opposite to the halogen lamp 210. The cover member 130 is formed in a substantially U shape in sectional view, and mainly includes a front wall 131 as an example of the second wall, a rear wall 132 as an example of the first wall, and a third wall. The upper wall part 133 as an example, the side wall part 134 as an example of a 4th wall, and the support wall part 135 extended toward the back from the lower end of the rear wall part 132 are provided.

  The front wall portion 131 and the rear wall portion 132 are disposed so as to face each other with the halogen lamp 210, the reflector 230, and the stay 240 sandwiched in the front-rear direction. The upper wall 133 is disposed on the upper side of the stay 240 (on the side opposite to the halogen lamp 210), and connects the upper end of the front wall 131 and the upper end of the rear wall 132.

  The support wall 135 is a wall that supports each temperature detection member 150, and causes each temperature detection member 150 to face each protrusion 222 of the nip plate 220 at a position corresponding to each protrusion 222 of the nip plate 220. Openings 136, 137, and 138 are formed so as to straddle the rear wall portion 132. Each opening 136 to 138 is formed in a shape corresponding to the shape of each temperature detection member 150. Moreover, each temperature detection member 150 may be positioned by being fitted in each opening 136-138.

  And as shown in FIG. 4, from each temperature detection member 150 set to each opening 136-138 of the support wall part 135, the electric wires 151 and 152 for conducting electricity are wired so that it may extend on the left-right direction outer side. ing. Specifically, each of the electric wires 151 and 152 is provided so as to crawl the surface on the outer side (opposite to the stay 240) of the cover member 130.

  More specifically, each of the electric wires 151 extending from the temperature detecting member 150 in the middle extends upward along the rear wall portion 132, is then bent forward along the upper wall portion 133, and extends in the front-rear direction of the upper wall portion 133. It is provided to be bent outward in the left-right direction at a substantially central position and to extend outward in the left-right direction. Further, the electric wires 152 extending from the respective temperature detection members 150 arranged on the outer side in the left-right direction are provided so as to extend outward in the left-right direction along the rear wall portion 132.

  As shown in FIGS. 5 and 6, the front wall 131, the rear wall 132, and the upper wall 133 have a plurality of front ribs 131 </ b> A protruding inward (stay 240 side) from the walls 131 to 133. A rear rib 132A and an upper rib 133A are provided. Here, the front rib 131A corresponds to an example of a second rib, the rear rib 132A corresponds to an example of a first rib, and the upper rib 133A corresponds to an example of a third rib.

  As shown in FIG. 2, each of the ribs 131 </ b> A to 133 </ b> A is in contact with the stay 240, whereby a space is formed between each of the wall portions 131 to 133 and the stay 240, and the space functions as a heat insulating layer. It is supposed to be.

  As shown in FIG. 5, the plurality of rear ribs 132 </ b> A are formed in an elongated shape along the vertical direction, and are arranged at intervals in the horizontal direction (the width direction of the fixing belt 110). Some of the plurality of rear ribs 132 </ b> A are provided adjacent to the openings 136 to 138. Thereby, the periphery of each opening 136-138 is reinforced by 132 A of back side ribs.

  The upper rib 133A continuously extends from one end side in the left-right direction to the other end side of the upper wall portion 133, and two upper ribs 133A are provided at intervals in the front-rear direction. As a result, as shown in FIG. 2, in a state where each upper rib 133A is in contact with the upper wall 241 of the stay 240, the space surrounded by the upper wall portion 133, each upper rib 133A and the upper wall 241 is air It is possible to make it a passage for passing through in the left-right direction.

  As shown in FIG. 6, the plurality of front ribs 131A are formed at positions corresponding to the rear ribs 132A in the left-right direction. The front rib 131A may be provided at a position different from the rear rib 132A in the left-right direction.

  As shown in FIG. 4, one side wall 134 is provided at each of the left and right ends of each of the walls 131 to 133 and connects the left and right ends of each of the walls 131 to 133. An opening 134A is formed at the upper part of each side wall 134 so as to face the gap between the two upper ribs 133A in the left-right direction. As a result, air is introduced into the cover member 130 from one opening 134A and discharged from the other opening 134A to the outside of the cover member 130 through the passage between the two upper ribs 133A. The air heated between the upper ribs 133A can be discharged out of the cover member 130 from the openings 134A on both sides. In order to create an air flow that passes from one opening 134A to the other opening 134A, for example, exhaust fans that exhaust the air inside the laser printer 1 to the outside are connected to the left and right sides of the main body housing 2. What is necessary is just to provide the ventilation fan which sends out air in any one wall, and opposes one opening part 134A.

According to the above, the following effects can be obtained in the present embodiment.
The wall portions 131 to 133 constituting the cover member 130 and the stay 240 are spaced apart by the ribs 131A to 133A provided on the wall portions 131 to 133, so that the wall portions 131 to 133 and the stay 240 are stayed with each other. A space as a heat insulating layer can be formed between the two and 240. Therefore, for example, the heat of the stay 240 can be prevented from being transmitted to the electric wires 151 and 152 via the wall portions 131 to 133 of the cover member 130 as compared with a structure in which the walls constituting the cover member are in close contact with the stay.

  Since the plurality of ribs 131A to 133A are provided at intervals with respect to the walls 131 to 133, the rigidity of the walls 131 to 133 can be improved.

  Since the rear ribs 132A are provided so as to be adjacent to the openings 136 to 138 formed in the cover member 130, the periphery of the openings 136 to 138 can be reinforced, and the rigidity of the rear wall 132 can be improved. it can.

  Since air can flow in the left-right direction between the two upper ribs 133A extending in the left-right direction, the stay 240 can be efficiently cooled by the air, and the amount of heat transmitted from the stay 240 to the cover member 130 can be reduced. Can be suppressed.

  By providing the opening 134A facing the gap between the two upper ribs 133A on the left and right side wall parts 134, the air heated between the two upper ribs 133A is discharged from one opening 134A to the outside, Unheated air can be taken from the opening 134A between the two upper ribs 133A. Therefore, the stay 240 can be efficiently cooled, so that the amount of heat transferred from the stay 240 to the cover member 130 can be kept small.

[Second Embodiment]
Next, a second embodiment will be described. In the embodiments described below including this embodiment, the same components as those described above are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in FIG. 7, the halogen lamp 210 generates heat with a first heat generation portion 210 </ b> A configured to generate heat at a predetermined heat generation amount TH or less and a heat generation amount greater than the predetermined heat generation amount TH in the left-right direction. It has the 2nd heat generating part 210B comprised. Specifically, the second heat generating portion 210B is provided on both sides of the first heat generating portion 210A in the left-right direction, and is configured such that the number of windings per predetermined length in the left-right direction of the filament 212 is greater than that of the first heat generating portion 210A. Has been. That is, the second heat generating portion 210B on both sides in the left-right direction is configured by winding the filament 212 more densely than the first heat generating portion 210A at the center in the left-right direction.

  The cover member 140 is configured by a front wall portion 141, a rear wall portion 142, and an upper wall portion 143 in a substantially U shape in sectional view, and in the left-right direction, a first portion 140A corresponding to the first heat generating portion 210A, and a first portion And a second portion 140B corresponding to the two heat generating portions 210B. A part corresponding to the first part 140A and the second part 140B of the rear wall part 142 is provided with a plurality of rear ribs 142A extending in the vertical direction and arranged in the horizontal direction. The front wall portion 141 is provided with a plurality of front ribs 141A that have the same shape as the plurality of rear ribs 142A and are arranged at the same position in the left-right direction. In FIG. 7, for the sake of convenience, the illustration of ribs provided on the upper wall portion 143 is omitted.

  The number of the rear ribs 142A disposed within the range of the unit length L in the left-right direction of the second portion 140B is the number of the rear ribs 142A disposed within the range of the unit length L in the left-right direction of the first portion 140A. Less than the number of Specifically, one rear rib 142A is provided in the range of the unit length L of the second portion 140B, and the rear rib 142A is provided in the range of the unit length L of the first portion 140A. Are provided. The number of front ribs 141A with respect to the unit length L is the same.

  Here, in the present embodiment, the unit length L may be a length in which at least two rear ribs 142A of the first portion 140A are disposed within the range. The number of the rear ribs 142A arranged within the range of the unit length L is the number of the rear ribs 142A arranged as a whole within the range, and only a part thereof is arranged within the range. The number of rear ribs 142A is not included. The relationship between the unit length L and the number of front ribs 142A is the same.

  According to this, since the number of the ribs 141A and 142A provided in the second portion 140B corresponding to the second heat generating portion 210B having a large heat generation amount is small, the ribs 141A and 142A are changed from the second heat generating portion 210B having a large heat generation amount. The amount of heat transmitted to each of the wall parts 141 and 142 via the can be kept small.

  In the present embodiment, the ribs 141A and 142A are provided in both the first portion 140A and the second portion 140B. However, the present invention is not limited to this. For example, the rib is not provided in the second portion. There may be. In this case, the unit length may be a length in which at least one rib of the first portion is disposed within the range.

  In addition, the configuration of the halogen lamp 210 illustrated in FIG. 7 is an example. That is, in FIG. 7, the heat generation amount of the halogen lamp 210 is larger than the center in the left-right direction on both sides in the left-right direction of the halogen lamp 210, but is not limited to this. The center may be larger than both sides in the left-right direction.

The present invention is not limited to the above embodiments, and can be used in various forms as exemplified below.
In each said embodiment, although the shape of the rib was made into linear form, this invention is not limited to this, Curve shape may be sufficient and a cylinder shape may be sufficient. In addition, as a cylindrical rib, a cylindrical rib and a polygonal rib may be sufficient, for example.

  For example, as shown in FIG. 8, a rectangular tube-shaped rib 130 </ b> A is formed on a front wall portion 131, a rear wall portion 132, and an upper wall portion 133 (not shown) constituting the cover member 130. Also good. According to this, the rigidity of each wall part 131-133 can be improved with the cylindrical rib 130A.

  Further, as shown in FIGS. 9A and 9B, the upper rib 133 </ b> B provided on the upper wall portion 133 of the cover member 130 is projected when projected in the direction from the pressure roller 120 toward the nip plate 220. 151 may be arranged so as not to overlap with 151. Specifically, the upper rib 133B has a shape such that a portion of the linear upper rib 133A in the first embodiment that overlaps the electric wire 151 is cut out.

  According to this, heat transmitted from the halogen lamp 210 via the stay 240 and the upper ribs 133A and 133B can be suppressed from being transmitted to the electric wire 151. Similarly, the rear rib provided on the rear wall portion 132 may be arranged so as not to overlap the electric wire 152 extending along the rear wall portion 132 when projected in the front-rear direction.

  Further, in the first embodiment, the front ribs 131A and the rear ribs 132A are formed so as to extend in the vertical direction, and the upper ribs 133A are formed so as to extend in the left-right direction. The extending direction of the rib can be set in an arbitrary direction.

  In each of the above embodiments, the halogen lamp 210 is exemplified as the heating element. However, the present invention is not limited to this. For example, the heating element may be a carbon heater or the like.

  In each said embodiment, although the nip board 220 was illustrated as an example of a nip member, this invention is not limited to this, For example, the thick member which is not plate shape may be sufficient.

  In the embodiment, the pressure roller 120 is illustrated as an example of the backup member, but the present invention is not limited to this, and the backup member may be, for example, a belt-shaped pressure member.

DESCRIPTION OF SYMBOLS 100 Fixing device 110 Fixing belt 120 Pressure roller 130 Cover member 131 Front wall part 131A Front side rib 132 Rear wall part 132A Rear side rib 133 Upper wall part 133A Upper side rib 151 Electric wire 210 Halogen lamp 220 Nip plate 240 Stay

Claims (8)

An endless fixing belt,
A heating element disposed inside the fixing belt and configured to generate heat;
A nip member disposed at a distance from the heating element and configured to receive radiant heat from the heating element;
A backup member that sandwiches the fixing belt with the nip member;
A stay disposed inside the fixing belt and supporting the nip member so as to cover the heating element;
A cover member disposed inside the fixing belt and covering the stay from a side opposite to the heating element;
Provided on the opposite side of the stay of the cover member, and an electric wire for conducting electricity,
The cover member is disposed on the opposite side of the heat generating body with respect to the stay, the first wall and the second wall facing each other across the heat generating body and the stay, and the first wall and the second wall A third wall connecting the walls, a first rib projecting from the first wall toward the stay and contacting the stay, and a first rib projecting from the second wall toward the stay and contacting the stay. and second rib, a third rib which contacts from said third wall to the stay to project toward the stay, was closed,
A plurality of the first ribs are provided at intervals in the width direction of the fixing belt,
The heating element includes a first heating part configured to generate heat with a predetermined heating value or less in the width direction, and a second heating part configured to generate heat with a heating value larger than the predetermined heating value. Have
The cover member includes a first portion corresponding to the first heat generating portion and a second portion corresponding to the second heat generating portion in the width direction,
The number of the first ribs arranged within the range of the unit length in the width direction of the second portion is the number of the first ribs arranged within the range of the unit length in the width direction of the first portion. A fixing device characterized by being less than the number. The electric wire is disposed on a surface of the third wall opposite to a surface on which the third rib is provided;
The fixing device according to claim 1 , wherein the third rib is disposed so as not to overlap the electric wire when projected in a direction from the backup member toward the nip member. An endless fixing belt,
A heating element disposed inside the fixing belt and configured to generate heat;
A nip member disposed at a distance from the heating element and configured to receive radiant heat from the heating element;
A backup member that sandwiches the fixing belt with the nip member;
A stay disposed inside the fixing belt and supporting the nip member so as to cover the heating element;
A cover member disposed inside the fixing belt and covering the stay from a side opposite to the heating element;
Provided on the opposite side of the stay of the cover member, and an electric wire for conducting electricity,
The cover member is disposed on the opposite side of the heat generating body with respect to the stay, the first wall and the second wall facing each other across the heat generating body and the stay, and the first wall and the second wall A third wall connecting the walls, a first rib projecting from the first wall toward the stay and contacting the stay, and a first rib projecting from the second wall toward the stay and contacting the stay. and second rib, a third rib which contacts from said third wall to the stay to project toward the stay, was closed,
The electric wire is disposed on a surface of the third wall opposite to a surface on which the third rib is provided;
The fixing device, wherein the third rib is disposed so as not to overlap the electric wire when projected in a direction from the backup member toward the nip member. The fixing device according to claim 3 , wherein the first rib has a cylindrical shape. The first wall has an opening for providing a temperature detection member for detecting the temperature of the nip member;
The fixing device according to claim 1, wherein the first rib is provided adjacent to the opening.   The plurality of third ribs extend from one end side in the width direction of the fixing belt toward the other end side, and a plurality of the third ribs are provided at intervals in a direction orthogonal to the width direction. 6. The fixing device according to any one of items 5. The cover member has a fourth wall connecting the first wall, the second wall, and the third wall at both ends in the width direction,
The fixing device according to claim 6, wherein the fourth wall has an opening facing the gap between the plurality of third ribs in the width direction.   The fixing device according to claim 1, wherein the third rib has a cylindrical shape.

Images