JP6347404B2 - Fixing device, image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus in a copying machine, a printer, a facsimile, or a complex machine including the fixing device.

  An image forming apparatus in a copying machine, a printer, a facsimile machine, or a complex machine thereof includes a fixing device for fixing an image transferred on a recording medium.

In a fixing device, a method is generally used in which toner on a recording medium is heated and melted by heat to fix a toner image on the recording medium. The fixing device includes a fixing member that fixes an image, a heating member such as a heater, and a heat transfer member that transfers heat from the heater to the fixing member.
In such a fixing device, there is a problem in that the heat generated in the heating member is efficiently transmitted to the fixing member, thereby saving the energy of the device and speeding up the fixing operation.

  In Patent Document 1 (Japanese Patent Laid-Open No. 4-44083), as shown in FIG. 11A, a recording medium is guided between a pressure roller 200 and a film 201, and is heated and melted and heated. A toner image is fixed on the recording medium. The film 201 is a heat resistant film and is stretched by a stay 202. The heating element 203 includes a heater base 203a, a heating element 203b, a surface protective layer 203c, and the like. The surface protective layer 203 c is in contact with the film 201 and transmits heat generated by the heating element 203 b to the film 201. A heat insulating member 204 is disposed around the heating body 203 and on the top of the heating body 203, making it difficult to transfer the heat of the heating body 203 to the surroundings and improving heat transfer to the film 201.

  In the invention of Patent Document 1, the surface protective layer 203c and the film 201 are in contact with each other over the entire width direction (left-right direction in the drawing) of the heating body 203. However, as shown in FIG. 11B, the surface C of the surface protective layer 203c in contact with the film 201 has a large difference in surface temperature, and the range B corresponding to the heating element 203b on the surface C and its surroundings. The temperature is high, and the temperature decreases as the distance from the range B increases.

  For this reason, when the heat generated by the heating element 203b is transmitted from the surface protective layer 203c to the film 201 and the film 201 reaches a high temperature, a back flow of heat occurs in the portion of the surface C where the surface temperature is low, and the film 201 forms a surface protective layer. Heat is transferred to 203c. This hinders heating of the film 201 and reduces the efficiency of the fixing operation.

  Under such circumstances, an object of the present invention is to provide a fixing device capable of efficiently transferring heat to a fixing member, realizing energy saving and speeding up of a fixing operation.

In order to solve the above problems, the present invention provides a fixing member that fixes an image on a recording medium, a heating member having a heat generating portion, and a heat transfer member that transmits heat from the heating member to the fixing member. A fixing device having a contact member disposed between and in contact with the heating member and the heat transfer member, and transmitting heat of the heating member to the heat transfer member; The surface on the heat transfer member side includes a heat generation region having the heat generation portion and a non-heat generation region not having the heat generation portion, and the contact member is a surface of the heating member on the heat transfer member side, Fixing is provided so as to correspond to a range where the heat generation area is provided, and the contact member is in contact with the heat generation area, and a predetermined gap is provided between the non-heat generation area and the heat transfer member. Features the device.

  In the fixing device of the present invention, the contact member contacts the heat generation region of the heating member, heat is transmitted from the heat generation region, and the transmitted heat is transmitted to the heat transfer member. The contact member also functions as a spacer that provides a predetermined gap between the non-heat generating region of the heating member and the heat transfer member. Thereby, the backflow of the heat from the heat transfer member to the non-heat generation region of the heating member can be prevented, and the heat generated in the heat generating portion can be efficiently transferred to the fixing member.

1 is a schematic configuration diagram of an image forming apparatus. 1 is a schematic configuration diagram of a fixing device. It is a schematic block diagram of a heating member. It is a perspective view of a fixing device. FIG. 6 is a schematic diagram showing an axial temperature distribution of the fixing belt. FIG. 6 is a cross-sectional view illustrating a problem of heat transfer to the fixing belt. 1 is a cross-sectional view illustrating a fixing device according to a first embodiment of the present invention. It is the figure which showed the backflow of the heat | fever from a sheet | seat member to a heating member. It is sectional drawing which showed the fixing device of 2nd embodiment of this invention. It is the schematic which showed another structure of this invention. It is a schematic block diagram of the conventional image forming apparatus.

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings. In addition, in each figure, the same code | symbol is attached | subjected to the part which is the same or it corresponds, The duplication description is simplified or abbreviate | omitted suitably.

(Description of image forming apparatus)
As shown in FIG. 1, the image forming apparatus 1 includes an exposure unit 2, an image forming unit 3, a transfer unit 4, a paper feeding unit 5, a conveyance path 6, a fixing device 7, and a discharge unit 8.

  The exposure unit 2 is located above the image forming apparatus 1 and is configured by a light source that emits laser light or the like and various optical systems. Specifically, by irradiating a laser beam for each color separation component of an image created based on image data obtained from an image acquisition unit (not shown) toward a photoconductor of the image forming unit 3 described later, The surface of the photoreceptor is exposed.

The image forming unit 3 is located below the exposure unit 2 and includes a plurality of process units 31 configured to be detachable from the image forming apparatus 1. Each process unit 31 has a photosensitive drum 32 that can carry toner as a developer on the surface, a charging roller 33 that uniformly charges the surface of the photosensitive drum 32, and a toner on the surface of the photosensitive drum 32. And a photoconductor cleaning blade 35 for cleaning the surface of the photoconductor drum 32.
Each process unit 31 includes four process units 31 (31Y, 31C, 31M, 31Bk) corresponding to different colors of yellow, cyan, magenta, and black, which are color separation components of a color image. Since the configuration is the same except that toners of different colors are accommodated, the reference numerals are omitted.

  The transfer unit 4 is located immediately below the image forming unit 3. The transfer unit 4 includes an endless intermediate transfer belt 43 that is stretched around a driving roller 41 and a driven roller 42 so as to be able to run around, a cleaning blade 44 that cleans the surface of the intermediate transfer belt 43, and the photosensitive of each process unit 31. The primary transfer roller 45 is disposed at a position facing the body drum 32 with the intermediate transfer belt 43 interposed therebetween. Each primary transfer roller 45 presses the inner peripheral surface of the intermediate transfer belt 43 at each position, and a primary transfer nip is formed at a place where the pressed portion of the intermediate transfer belt 43 and each photosensitive drum 32 come into contact with each other. Has been.

  A secondary transfer roller 46 is disposed at a position opposite to the drive roller 41 of the intermediate transfer belt 43 and the drive roller 41 across the intermediate transfer belt 43. The secondary transfer roller 46 presses the outer peripheral surface of the intermediate transfer belt 43, and a secondary transfer nip is formed at a location where the secondary transfer roller 46 and the intermediate transfer belt 43 are in contact with each other. Further, a waste toner container 47 for storing waste toner cleaned by the cleaning blade 44 is disposed below the intermediate transfer belt 43 via a waste toner transfer hose (not shown).

  The paper feed unit 5 is located below the image forming apparatus 1, and includes a paper feed cassette 51 that stores recording paper P as a recording medium, a paper feed roller 52 that carries the recording paper P out of the paper feed cassette 51, and the like. It is made up of.

  The conveyance path 6 is a conveyance path for conveying the recording paper P carried out from the paper supply unit 5, and a pair of conveyance rollers (not shown) extends to the discharge path 8 described later in addition to the pair of registration rollers 61. It is arranged appropriately in the middle of.

  The fixing device 7 includes a fixing belt 72 as a fixing member heated by a heating member 71, a pressure roller 73 that can press the fixing belt 72, and the like.

  The discharge unit 8 is provided on the most downstream side of the conveyance path 6 of the image forming apparatus 1. The discharge unit 8 is provided with a pair of discharge rollers 81 for discharging the recording paper P to the outside and a discharge tray 82 for stocking the discharged recording medium.

  The basic operation of the image forming apparatus 1 will be described below with reference to FIG.

  In the image forming apparatus 1, when an image forming operation is started, an electrostatic latent image is formed on the surface of the photosensitive drum 32 of each process unit 31Y, 31C, 31M, 31Bk. The image information to be exposed on each photosensitive drum 32 is single-color image information obtained by separating a desired full-color image into color information of yellow, cyan, magenta, and black. An electrostatic latent image is formed on each photosensitive drum 32, and the toner stored in each developing device 34 is supplied to the photosensitive drum 32 by the developing roller 36, so that the electrostatic latent image is a visible image. It is visualized as a certain toner image (developer image).

  Next, the driving roller 41 of the transfer unit 4 is driven to rotate counterclockwise in the figure, so that the intermediate transfer belt 43 is driven in the direction indicated by the arrow A in the figure. In addition, each primary transfer roller 45 is applied with a constant voltage or a constant current controlled voltage having a polarity opposite to the charging polarity of the toner. As a result, a transfer electric field is formed at the primary transfer nip between each primary transfer roller 45 and each photosensitive drum 32. The color toner images formed on the photosensitive drums 32 of the process units 31Y, 31C, 31M, and 31Bk are sequentially superimposed on the intermediate transfer belt 43 by the transfer electric field formed in the primary transfer nip. Transcribed. Thus, a full-color toner image is formed on the surface of the intermediate transfer belt 43. The toner remaining on the photosensitive drum 32 after the primary transfer is removed by the photosensitive member cleaning blade 35 and stored in a waste toner container 47.

  On the other hand, when the image forming operation is started, in the lower part of the image forming apparatus 1, the sheet feeding roller 52 of the sheet feeding unit 5 is rotationally driven, whereby the recording sheet P accommodated in the sheet feeding cassette 51 is transported 6. Sent out. The recording paper P sent to the conveyance path 6 is timed by the registration roller 61 and sent to the secondary transfer nip between the secondary transfer roller 46 and the driving roller 41 facing the recording roller P. At this time, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the intermediate transfer belt 43 is applied to the secondary transfer roller 46, thereby forming a transfer electric field in the secondary transfer nip. Then, the toner images on the intermediate transfer belt 43 are collectively transferred onto the recording paper P by the transfer electric field formed in the secondary transfer nip.

  The recording paper P to which the toner image has been transferred is conveyed to the fixing device 7, and the recording paper P is heated and pressed by the fixing belt 72 and the pressure roller 73 heated by the heating member 71, so that the toner image is formed. It is fixed on the recording paper P. Then, the recording paper P on which the toner image is fixed is separated from the fixing belt 72, conveyed by a pair of conveyance rollers (not shown), and discharged to a discharge tray 82 by a discharge roller 81 in a discharge unit 8. Further, residual toner adhering to the intermediate transfer belt 43 after the transfer is removed by the cleaning blade 44 or the like. The removed toner is conveyed to a waste toner container 47 and collected by a screw or a waste toner transfer hose (not shown).

  The above description is an image forming operation when a full-color image is formed on the recording paper P. A single color image can be formed using any one of the four process units 31Y, 31C, 31M, and 31Bk. It is also possible to form two or three color images using two or three process units 31.

(Description of fixing device)
As shown in FIG. 2, the fixing device 7 includes a heating member 71, a fixing belt 72, a pressure roller 73, a curved surface member 101 as a heat transfer member, a rotating shaft 102 of the curved surface member 101, a pressure member 103, a spring 104, It comprises a stay 105, a nip forming member 106, a temperature sensor 107, and the like.

  The fixing belt 72 has a SUS base having an outer diameter of 30 mm and a thickness of 40 μm, and an elastic layer coated on the surface of the base. The elastic layer is made of silicone rubber and has a thickness of 100 μm.

  A release layer having a thickness of 5 to 50 μm is formed on the surface of the fixing belt 72 with a fluorine-based resin such as PFA or PTFE in order to enhance durability and ensure releasability. The base of the fixing belt 72 may be polyimide.

  The pressure roller 73 includes an iron core bar having an outer diameter of 30 mm and a thickness of 2 mm, and an elastic layer coated on the surface of the core bar. The elastic layer is made of silicone rubber and has a thickness of 5 mm. It is desirable to form a fluororesin layer having a thickness of about 40 μm on the surface of the elastic layer in order to improve the releasability.

  The pressure roller 73 is pressed toward the fixing belt 72 by a pressing unit (not shown) and is in contact with the nip forming member 106 via the fixing belt 72. A nip portion N having a predetermined width is formed at a location where the pressure roller 73 and the fixing belt 72 are in pressure contact with each other. The pressure roller 73 is configured to be rotationally driven by a drive source such as a motor (not shown) provided in the main body of the image forming apparatus 1. When the pressure roller 73 is rotationally driven, the driving force is transmitted to the fixing belt 72 at the nip portion N, and the fixing belt 72 is driven to rotate.

  The fixing belt 72 to which heat of a heat generating portion 71 a of the heating member 71 described later is transmitted presses and heats the recording paper P conveyed to the nip portion N with the pressure roller 73, thereby recording paper. The toner image on the surface of P is fixed.

  The stay 105 holds the rotating shaft 102 on one end side, and the curved surface member 101 is configured to be rotatable about the rotating shaft 102. The stay 105 holds the nip forming member 106 at the end opposite to the side holding the rotating shaft 102. The curved surface member 101 and the nip forming member 106 stretch the fixing belt 72. The spring 104 has one end fixed to the stay 105 and the other end fixed to the pressure member 103 to press the pressure member 103 toward the heating member 71 and the fixing belt 72.

  FIG. 3 is a view of the heating member 71 viewed from the direction D of FIG. The heating member 71 includes a heat generating portion 71a and a substrate 71b that is formed of a glass material having low thermal conductivity and is disposed so as to surround the heat generating portion 71a. The width of the heating member 71 (the length in the horizontal direction in the figure), that is, the width of the substrate 71b is 10 mm, the width of the heat generating portion 71a is 3 mm, and the heat generating portion 71a is arranged at the center in the width direction of the heating member 71. Has been. A thermal heater or the like is used for the heat generating portion 71a.

  The substrate 71b is formed of a glass material having low thermal conductivity, covers the periphery of the heat generating portion 71a, and is disposed on the side opposite to the side on which the curved surface member 101 is disposed, thereby pressurizing the heat of the heat generating portion 71a. Heat transfer from the heat generating portion 71a to the curved surface member 101 can be performed efficiently, making it difficult to transfer to the member 103 side.

  The pressure member 103 holds the heating member 71 from the side opposite to the side where the heat generating portion 71a is disposed. The pressure member 103 has a gap 103a for making it partially non-contact with the heating member 71 at a position corresponding to the heat generating portion 71a.

  By providing the gap 103a, it is difficult to transfer the heat of the heat generating part 71a in the direction of the pressure member 103, and by providing it at a position corresponding to the heat generating part 71a, a heat transfer path from the heat generating part 71a to the pressure member 103 is provided. It is possible to lengthen and make it difficult to transfer heat.

  Further, the pressing member 103 and the heating member 71 are in surface contact, and the spring 104 presses the heating member 71 via the pressing member 103, so that the pressing direction from the spring 104 to the heating member 71 is stable. To do.

  The pressure member 103 is preferably composed of a resin member having low thermal conductivity in order to prevent the heat of the heating member 71 from being transferred to the stay 105 via the spring 104.

  The heating member 71 held by the pressure member 103 is pressed in the direction of the curved surface member 101 by the bias of the spring 104, and the curved surface member 101 is pressed by the heating member 71 and pressed against the fixing belt 72. Yes.

  Due to the bias of the spring 104, the heating member 71 comes into contact with the curved surface member 101, and the heat of the heat generating portion 71 a can be transmitted to the curved surface member 101.

  The curved surface member 101 is rotatable about a rotation shaft 102 fixed to the stay 105, and is energized by a spring 104 to generate a force to rotate in the direction of the fixing belt 72. The fixing belt 72 is pressed by the force to rotate in the direction of, and the fixing belt 72 is stretched.

  In this way, the urging force of the spring 104 functions as a pressing force for transmitting the heat of the heat generating portion 71a, and also functions as a pressing force for stretching the fixing belt 72.

  A temperature sensor 107 is provided on the inner peripheral surface of the fixing belt 72. The surface temperature of the fixing belt 72 detected by the temperature sensor 107 is transmitted to the control means 108 connected to the temperature sensor 107.

  The control means 108 is constituted by a microcomputer including a CPU, ROM, RAM, I / O interface and the like. The control means 108 is connected to the power source 109 of the heat generating part 71a. The control unit 108 adjusts the surface temperature of the fixing belt 72 by switching whether or not the heat generating portion 71 a generates heat according to the surface temperature of the fixing belt 72 detected by the temperature sensor 107.

  As shown in FIG. 4, a plurality of heating members 71 are arranged on the inner peripheral surface of the fixing belt 72 in the axial direction of the pressure roller 73. Depending on the size of the recording paper P on which an image is formed and the image range to be formed, the fixing belt 72 can be partially heated in the axial direction to save energy.

  The curved surface member 101 is preferably composed of a member having good thermal conductivity such as aluminum in order to efficiently transfer heat to the fixing belt 72.

  As shown in FIG. 5, when the recording paper P having a narrow width is continuously formed, the fixing belt 72 that does not pass the recording paper P with respect to the heated area E in the axial direction of the fixing belt 72. Both end portions 72f of the heated region E are generated, and heat is not transferred to the recording paper P in this portion. For this reason, as indicated by the surface temperature in the axial direction of the fixing belt 72 shown in the upper side of FIG. 5, only the portions of both end portions 72f may be hotter than the surroundings.

  By configuring the curved surface member 101 with a material having good thermal conductivity, it becomes easy for the heat at both ends 72f, which has become high temperature, to flow back to the curved surface member 101, and the fixing belt 72 is prevented from partially becoming high temperature. Can do.

(Problem of the present invention)
FIG. 6 shows the structure around the heat generating portion 71 a of the heating member 71.
The heating member 71 has a heat generating portion 71 a, and transfers heat generated from this portion to the curved surface member 101 and from the curved surface member 101 to the fixing belt 72.

  The heating member 71 is pressed in the direction of the fixing belt 72 by the bias from the spring 104, and the heat generating portion 71 a is in contact with the curved surface member 101. Further, in order to stabilize the direction of pressing from the heating member 71 to the fixing belt 72, the curved surface member 101 is provided with a recess 101c.

  In such a fixing device, one of the problems is to efficiently transfer the heat of the heating member 71 to the fixing belt 72 in order to save energy of the entire device and speed up the fixing operation. In order to efficiently transfer the heat of the heating member 71 to the fixing belt 72, it is necessary that the heat is efficiently transferred between the heat generating portion 71a and the curved surface member 101.

  Therefore, a configuration in which a coating agent such as grease having good thermal conductivity is applied between the heat generating portion 71a and the curved surface member 101 is conceivable. By applying the grease, heat is easily transmitted between the heat generating portion 71 a and the curved surface member 101, and heat can be efficiently transmitted to the fixing belt 72.

  However, in the configuration in which an application agent such as grease is applied, if there is unevenness in the application condition of the grease, heat transfer is not sufficiently performed in the thinly applied part, and the heat generating portion 71a locally becomes high in that part, There is a possibility that partial wear of the heat generating portion 71a may occur. Further, when the grease is heated by the heat generating portion 71a, there is a possibility that volatile organic compounds (Volatile Organic Compound) or ultra fine particles (Ultra Fine Particle) of submicron (0.1 μm) or less are generated from the grease.

(Fixing device of first embodiment of the present invention)
Therefore, in the fixing device according to the first embodiment of the present invention, as shown in FIG. 7, instead of applying a coating agent such as grease in order to improve the thermal conductivity of the heat generating portion 71 a and the curved surface member 101. In addition, a sheet member 110 as a contact member made of a member having excellent thermal conductivity is provided between the two. A gap F is provided between the heating member 71 and the curved surface member 101.

  The sheet member 110 is in contact with the adjacent surface 71c, which is the surface of the heating member 71 on the sheet member 110 side, and the surface opposite to the surface in contact with the adjacent surface 71c is in contact with the convex portion 101b of the curved surface member 101. . The heat generated in the heat generating portion 71 a is transmitted from the heat generating portion 71 a to the sheet member 110, from the sheet member 110 to the curved surface member 101, and from the curved surface member 101 to the fixing belt 72.

  In the configuration of the present invention, by providing the sheet member 110 having excellent thermal conductivity between the heat generating portion 71a and the curved surface member 101, heat can be efficiently transmitted from the heat generating portion 71a to the curved surface member 101. .

  The sheet member 110 is made of porous metal paper, foamed aluminum, carbon fiber paper, or the like that has high thermal conductivity and excellent flexibility and flexibility.

  By using a material having excellent flexibility for the sheet member 110, when the sheet member 110 is pressed against the curved member 101 by the bias from the spring 104, the sheet member 110 is elastically deformed, and the curved member 101 and the heating member are heated. It is possible to abut against the member 71 without creating a gap.

  In the configuration using the sheet member 110, there is no gap between the curved surface member 101 and the heating member 71, and no volatile organic compound or ultrafine particles are generated by being heated by the heat generating portion 71 a. The above-described problems in the configuration using grease can be solved.

  In addition, the sheet member 110 abuts only on the heat generation area 71d, which is a part having the heat generation part 71a, of the adjacent surface 71c of the heating member 71, and does not contact the non-emission area 71e, which is a part not having the heat generation part 71a. By adopting the configuration, the efficiency of heat transfer is improved. The adjacent surface 71c has non-heat generating regions 71e on both sides of the heat generating region 71d.

  Here, as a comparison with the configuration of the present invention, consider a configuration in which the sheet member 110 is in contact with the entire surface of the adjacent surface 71c as shown in FIG.

  The substrate 71b is made of a glass material having low thermal conductivity so that heat of the heat generating portion 71a is not transmitted to the pressure member 103 side as much as possible. For this reason, when heat is transmitted from the heat generating portion 71a to the sheet member 110, the sheet member 110 becomes hotter than the substrate 71b.

  When the sheet member 110 has a higher temperature than the substrate 71b, a part of the heat transferred from the heat generating portion 71a to the sheet member 110 flows backward from the non-heat generating region 71e to the substrate 71b. Thereby, the heat transfer efficiency from the heat generating portion 71a to the curved surface member 101 via the sheet member 110 is lowered.

  On the other hand, in the configuration of the present invention, the sheet member 110 does not come into contact with the non-heat generating area 71e, so that the heat transmitted from the heat generating portion 71a does not flow back to the non-heat generating area 71e.

  Accordingly, heat is efficiently transmitted from the heat generating portion 71 a to the sheet member 110, and heat is efficiently transmitted from the sheet member 110 to the curved surface member 101 and from the curved surface member 101 to the fixing belt 72.

  Further, by sandwiching the sheet member 110 between the heat generating portion 71a and the curved surface member 101, a gap F is formed between the non-heat generating region 71e of the heat generating portion 71a and the surface 101a facing the non-heat generating region 71e of the curved surface member 101. Provided. By providing the gap F, heat does not flow back from the surface 101a of the curved member 101 to which heat is transmitted from the sheet member 110 to the non-heat generating region 71e of the heating member 71, and efficient heat transfer to the curved member 101 is achieved. Is done.

  The sheet member 110 abuts on the convex portion 101 b of the curved surface member 101. By providing the convex portion 101b on the curved surface member 101, the contact position of the sheet member 110 with respect to the curved surface member 101 can be limited to the convex portion 101b, and the contact position is stabilized. Further, since the gap F can be made longer than the thickness of the sheet member 110, the gap F can be more reliably provided between the curved surface member 101 and the substrate 71b so that they are not in contact with each other.

  As described above, in the configuration of the present invention, by providing the sheet member 110, the heat generated in the heat generating portion 71a is not caused to flow backward, and the heat can be efficiently transmitted to the fixing belt 72.

  As shown in FIG. 4, the fixing device 7 of the present invention is configured to have a plurality of heating members 71 in the axial direction of the fixing belt 72. Then, as many springs 104 as the heating members 71 are arranged in the axial direction are arranged to press the heating members 71 toward the curved surface member 101.

  The sheet members 110 are not necessarily provided on a one-to-one basis for all the heating members 71. For example, when there is a situation in which heat is not easily transmitted to the fixing belt 72 only at both ends in the axial direction of the fixing belt 72, the sheet member 110 is provided only for the heating member 71 disposed at both ends. It is also possible. Further, the present invention is not limited to the configuration in which a plurality of heating members 71 are provided in the axial direction, and can be applied to only one configuration.

(Fixing device of the second embodiment of the present invention)
In the configuration of the first embodiment of the present invention, the sheet member 110 is disposed between the heat generating portion 71a and the curved surface member 101, the curved surface member 101 does not contact the non-heat generating region 71e, and there is a gap F therebetween. Although the configuration is adopted, a configuration in which the curved surface member 101 and the non-heat generating region 71e partially abut may be employed.

  In the second embodiment of the present invention, as shown in FIG. 9, the curved surface member 101 has a contact portion 101d on one side (left side in the drawing) of the recess 101c. The contact portion 101d contacts one side (left side in the figure) of the non-heat generation region 71e disposed on both sides of the heat generation region 71d, and does not have a gap F on this side.

  In the configuration of the second embodiment, as compared with the fixing device of the first embodiment, part of the heat transferred from the heat generating portion 71a to the curved surface member 101 via the sheet member 110 is transferred from the contact portion 101d to the substrate 71b. Since the heat flows back to the non-heat generating area 71e, the heat transfer efficiency to the fixing belt 72 is lowered.

  However, the contact of the heating member 71 and the sheet member 110 with respect to the curved surface member 101 is more stable when the substrate 71b comes into contact with the contact portion 101d than in the configuration having the gap F on both sides as in the first embodiment. Further, the efficiency of heat transfer to the fixing belt 72 is better than the configuration in which the gap F does not exist.

  In the configuration of the present invention so far, the sheet member 110 is in contact with only the heat generation area 71d of the adjacent surface 71c. However, for example, as shown in FIG. 10, the width of the sheet member 110 may be slightly wider than the width of the heat generating portion 71a, and the sheet member 110 may partially abut against the non-heat generating region 71e. Even if the sheet member 110 is configured to partially contact the non-heat generating area 71e, by providing a portion that does not contact the non-heat generating area 71e, the backflow of heat from the sheet member 110 to the heating member 71 is reduced and fixing is performed. The effect of improving the efficiency of heat transfer to the belt 72 is also obtained. Furthermore, since the substrate 71b in the vicinity of the heat generating portion 71a is also at a high temperature, the backflow of heat from the sheet member 110 to the substrate 71b is considered to be limited. Moreover, by having the space | gap F, the backflow of the heat from the curved surface member 101 to the board | substrate 71b can be prevented.

The embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the gist of the present invention.
The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may be a monochrome image forming apparatus, a copying machine, a printer, a facsimile, or a complex machine thereof.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 7 Fixing apparatus 71 Heating member 71a Heat generating part 71b Substrate 71c Adjacent surface 71d Heat generating area 71e Non-heat generating area 72 Fixing belt (fixing member)
101 Curved surface member (heat transfer member)
101b Convex part 101d Contact part 104 Spring 110 Sheet member (contact member)

JP-A-4-44083

Claims (7)

In a fixing device having a fixing member for fixing an image on a recording medium, a heating member having a heat generating portion, and a heat transfer member for transmitting heat from the heating member to the fixing member.
Between the heating member and the heat transfer member, it is disposed in contact with both, and has a contact member that transmits heat of the heating member to the heat transfer member,
The heating member includes a heat generating region having the heat generating portion and a non-heat generating region not having the heat generating portion on a surface on the heat transfer member side,
The contact member is provided so as to correspond to a range in which the heat generation region is provided in the surface of the heating member on the heat transfer member side,
The fixing device is characterized in that the abutting member abuts on the heat generating area, and a predetermined gap is provided between the non-heat generating area and the heat transfer member.   The fixing device according to claim 1, wherein the heat transfer member has a protrusion that contacts the contact member.   3. The fixing device according to claim 1, wherein the abutting member abuts only on the heat generation area of the surface of the heating member on the heat transfer member side.   The fixing device according to claim 1, wherein the contact member is made of a flexible member.   The fixing device according to claim 4, wherein the contact member is made of a porous metal material.   The fixing device according to claim 4, wherein the contact member is made of a carbon fiber material.   An image forming apparatus comprising the fixing device according to claim 1.

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