JP2017138358A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that can suppress unevenness in temperature in a fixing device including a heating element as part of a layer of a rotor.SOLUTION: In a fixing device comprising a rotor 36 that includes a heating element 36b and a pressure body that is in pressure contact with the rotor 36 to form a fixing nip part, the rotor 36 includes a conductive layer 36a formed with the heating element 36b as an outer layer; the heating element 36b includes a cylindrical part that is formed on the conductive layer 36a to continue over the entire periphery in the direction of rotation of the rotor 36 and fed with power from a power feeding member, and divided parts that are formed on the conductive layer 36a at intervals in the rotation direction.SELECTED DRAWING: Figure 3

Description

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

  As a fixing device used in an image forming apparatus such as a printer or a copying machine, there is a configuration including a roller or a film as a rotating body and a pressure roller as a pressure body that presses the film to form a fixing nip portion. Are known. Patent Documents 1, 2, and 3 disclose a fixing device that is provided with a heating element as a part of a layer constituting a roller or a film, and that power is supplied to the heating element to cause resistance heating, thereby achieving high-speed startup and energy saving. Is disclosed.

JP 2004-279547 A JP-A-9-16013 Japanese Patent Laid-Open No. 9-22208

  In the fixing devices disclosed in Patent Documents 1, 2, and 3, temperature unevenness may occur between a portion where a heating element is present and a portion where a roller or a film is not present.

  An object of the present invention is to provide a technology capable of suppressing temperature unevenness in a fixing device including a heating element as a part of a layer of a rotating body.

In order to achieve the above object, the fixing device of the present invention includes:
In a fixing device comprising: a rotating body having a heating element; and a pressing body that presses against the rotating body to form a fixing nip portion;
The rotating body has a conductive layer in which the heating element is formed as an outer layer,
The heating element is formed on the conductive layer so as to be continuous over the entire circumference in the rotation direction of the rotating body, and is spaced from the cylindrical portion that receives power from a power supply member in the rotation direction on the conductive layer. And a divided portion formed.
In order to achieve the above object, an image forming apparatus of the present invention includes:
An image forming unit for forming a developer image on a recording material;
The fixing device for fixing the developer image on the recording material; and
It is characterized by providing.

  According to the present invention, it is possible to suppress temperature unevenness in a fixing device that includes a heating element as part of a layer constituting a rotating body.

1 is a schematic cross-sectional view of a fixing device according to Embodiment 1 of the present invention. 1 is a schematic front view of a fixing device according to a first embodiment of the present invention. The typical perspective view which shows the structure of the film 36 in Example 1 of this invention. Typical sectional drawing which shows the layer structure of the film 36 in Example 1 of this invention Schematic which shows the electrical connection in Example 1 of this invention The figure which shows the temperature nonuniformity of the film 36 surface in Example 1 of this invention. The figure which shows the flow of the electric current at the time of the film 36 damage in Example 1 of this invention Schematic sectional view of a fixing device according to Embodiment 2 of the present invention. Schematic front view of a fixing device according to Embodiment 2 of the present invention. Schematic perspective view showing the configuration of the fixing roller 62 in Embodiment 2 of the present invention. Schematic sectional view showing the layer structure of the fixing roller 62 in Embodiment 2 of the present invention. Schematic which shows the electrical connection in Example 2 of this invention The typical perspective view which shows the structure of the film 136 in the comparative example of this invention. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. That is, it is not intended to limit the scope of the present invention to the following embodiments.

[Example 1]
A fixing device and an image forming apparatus according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 7, 13, and 14. FIG. 1 is a schematic cross-sectional view showing the main part of the fixing device 18 according to the present embodiment, and FIG. 2 is a schematic front view of the fixing device 18 according to the present embodiment, omitting the central portion in the longitudinal direction. FIG. 4 is a view showing only the periphery of both ends. In the following description of the apparatus constituent members, the longitudinal direction (bus line direction) is the X-axis direction in the figure, the width direction is the Y-axis direction that is the recording material conveyance direction, and the height direction is the Z-axis direction. is there.

  The fixing device 18 is of a resistance heating type, and causes resistance heating (Joule heating) by directly passing a current through a heating pattern (heating body) formed as a part of a layer constituting the film 36 (rotating body). It is. This method heats the film 36 more directly to the fixing device using a halogen heater or the like as a heat source, so that the temperature can be increased at high speed, and high-speed start-up and energy saving can be achieved in a shorter time. There is an advantage of being able to plan.

  The fixing device 18 is provided in an image forming apparatus such as a printer or a copying machine that forms an image on a recording material by an electrophotographic method. The present invention can be applied not only to the fixing device as in the present embodiment but also to an image heating device that performs surface treatment such as applying gloss to the image forming surface of a recording material as heat treatment. is there.

  FIG. 14 is a schematic configuration diagram of an image forming apparatus (laser beam printer) 10 in the present embodiment. The photosensitive drum 1 as an image carrier is rotationally driven in the direction of the arrow, and the surface is uniformly charged by a charging roller 2 as a charging device. The laser scanner 3 (exposure device) performs scanning exposure on the charged photosensitive drum 1 with a laser beam L that is ON / OFF controlled according to image information, and forms an electrostatic latent image on the photosensitive drum 1. The developing device 4 develops a toner image (developer image) on the photosensitive drum 1 by attaching toner to the electrostatic latent image. The toner image formed on the photosensitive drum 1 is conveyed at a predetermined timing from the sheet feeding cassette 6 by a conveyance mechanism such as a conveyance roller 8 in a transfer nip portion that is a pressure contact portion between the transfer roller 5 and the photosensitive drum 1. Transferred to the recording material P. The recording material P on which the toner image is transferred and formed in the image forming unit configured as described above is conveyed to the fixing device 18 as a fixing unit, and the toner image is heated and fixed on the recording material P in the fixing device 18. The paper is discharged onto a paper discharge tray.

The fixing device 18 according to the present embodiment generally includes a film assembly 31 including a film 36 as a rotating body, and a pressure roller 32 as a pressure body. Form. The recording material P carrying an unfixed toner image is nipped and conveyed at the fixing nip portion, whereby the toner image is fixed to the recording material P by heating. The pressure roller 32 and the film assembly 31 are arranged between the left and right side plates 34 substantially in parallel vertically, and the left and right side plates 34 are fixed to the apparatus frame 33.

  FIG. 3 is a schematic perspective view showing the configuration of the film 36. The film 36 is a flexible cylindrical member in which a heat generation pattern 36b serving as a heat generating element is provided on a base layer 36a that is a conductive layer, and an elastic layer 36c and a release layer 36d are further formed thereon. In FIG. 3, in order to easily understand the configuration of the heat generation pattern 36b, the elastic layer 36c and the release layer 36d are partially omitted. 4A and 4B are schematic cross-sectional views showing the layer structure of the film 36. FIG. 4A is a cross-sectional view of the film 36 in the longitudinal direction, and FIG. 4B is a cross-sectional view of the central portion. Yes. In addition, since each figure has shown the structure intelligibly, ratios, such as the width | variety and the space | interval of the heat_generation | fever pattern 36b, the thickness of each layer, are not shown in figure correctly.

  In this embodiment, as the base layer 36a, a polyimide base material added with conductivity by adding a conductive filler having a thickness of about 60 μm formed in a cylindrical shape is used. On the base layer 36a, a heat generation pattern 36b having a thickness of about 10 μm is formed as an outer layer. An elastic layer 36c made of silicone rubber, fluorine rubber, or the like having a thickness of about 200 μm is formed on the heat generating pattern 36b, and further, a release layer 36d of a PFA resin tube having a thickness of about 15 μm is coated thereon. . In this embodiment, the film 36 having an inner diameter of about 18 mm is used.

  The heat generation pattern 36b is formed over the entire circumference of the film 36 at a width of about 10 mm at both ends in the longitudinal direction (direction orthogonal to the rotation direction of the film 36), and the region between them is divided in the rotation direction of the film 36. It is a thin line. That is, the heat generating pattern 36b is spaced from the portion (cylindrical portion) formed so as to be continuous over the entire circumference in the rotation direction of the film 36 at both ends in the longitudinal direction on the conductive layer, and in the rotation direction of the film 36 on the conductive layer. And a portion (divided portion) formed with a gap. A plurality of thin wires (band-like portions) constituting the divided portion are formed so as to extend in the longitudinal direction from the cylindrical portion so as to connect one cylindrical portion and the other cylindrical portion, and a film is formed on the conductive layer. A plurality are formed at predetermined intervals over the entire circumference in 36 rotation directions. Each thin line is substantially parallel, the width is about 0.5 mm, and the distance between the thin lines is about 2 mm. Since the thin wire portion (divided portion) has a relatively high resistance with respect to both end portions (tubular portions), the amount of heat generation increases. As a method for forming the heat generation pattern 36b, there are means such as printing, plating, sputtering, and vapor deposition. In this embodiment, the heat generation pattern 36b is formed by screen printing with silver ink.

  The pressure roller 32 includes a cored bar 32a, an elastic layer 32b made of silicone rubber, fluororubber, or the like formed concentrically around the cored bar 32a, and a PFA, PTFE, FEP or the like as the outermost layer. A mold layer 32c is formed. In this embodiment, an elastic layer 32b of a silicone rubber layer having a thickness of about 3.5 mm is formed by injection molding on a core metal 32a made of stainless steel and having an outer diameter of 11 mm, and further a PFA coating layer having a thickness of about 40 μm is formed thereon. A pressure roller 32 on which a release layer 32c was formed was used. The outer diameter of the roller is about 18 mm. The hardness of the pressure roller 32 is preferably in the range of 40 ° to 70 ° from the viewpoint of securing the fixing nip N, durability, and the like at a load of 9.8 N with an ASKER-C hardness meter. In this embodiment, the angle is set to 54 °. As shown in FIG. 2, the pressure roller 32 is rotatably supported between the apparatus frame side plates 34 via bearing members 35 at both ends in the longitudinal direction of the cored bar 32a. G is a drive gear fixed to one end of the core metal 32a. A rotational force is transmitted to the drive gear G from a drive mechanism (not shown), and the pressure roller 32 is rotationally driven.

As shown in FIG. 1, the film assembly 31 is an assembly of a film 36, a power feeding member 37, a pressure holder 38, a pressure stay 40, a flange 41, and the like. Film 36 is
Heat is generated by receiving power supply from the power supply member 37. The pressure holder 38 and the pressure stay 40 function as a nip portion forming member that guides the film 36 from the inside and forms a nip portion with the pressure roller 32 via the film 36. The flanges 41 arranged on the left and right of the film 36 function as a regulating member that regulates the movement of the film 36 in the longitudinal direction.

  The power supply member 37 is made of a conductive material such as metal or carbon, and is fixed to the pressure holder 38. As shown in FIG. 2, the power supply member 37 (37 a, 37 b) is pressed from the inner surface of the film 36 against a region (cylindrical portion) where the heat generation pattern 36 b at the end of the film 36 is formed over the entire circumference. It has been. As shown in FIG. 1, the pressure holder 38 is a member having a substantially semicircular saddle shape in cross section and having rigidity, heat resistance, and heat insulation, and is made of a liquid crystal polymer or the like. The pressure holder 38 serves as a rotation guide for the film 36 fitted on the pressure holder 38, serves as a nip portion forming member, and further serves to hold the power supply member 37. The pressure stay 40 is a horizontally long rigid member having a U-shaped cross section. The power supply member 37 is attached to the depression on the lower surface of the pressure holder 37, the film 36 is covered on the outside, and the pressure stay 40 is inserted inside the pressure holder 38. The left and right flanges 41 are fitted to the left and right outward extending arm portions of the pressure stay 40, respectively. Thus, the film assembly 31 is assembled.

  As shown in FIG. 1, the film assembly 31 is arranged between the left and right side plates 34 so as to be substantially parallel to the upper side of the pressure roller 32 with the power supply member 37 facing upward. In the left and right flanges 41, vertical groove portions 41a provided in the left and right flanges 41 are engaged with vertical edge portions 40a provided in the left and right side plates 34, respectively. In this embodiment, a liquid crystal polymer resin is used as the material of the flange 41. The left and right side plates 34 are fixed to the apparatus frame 33 and form a frame of the fixing device 18.

  Then, as shown in FIG. 2, the pressure spring 45 is contracted between the pressure portions 41 b of the left and right flanges 41 and the pressure arms 44. As a result, the left and right flanges 41, the pressure stay 40, and the pressure holder 38 are pressed against the lower surface of the pressure roller 32 with a predetermined pressing force with the film 36 interposed therebetween. In this embodiment, the pressure of the pressure spring 45 is set so that the pressure between the film 36 and the pressure roller 32 is 160 N in total pressure. By this pressurization, the pressure holder 38 is pressed against the upper surface of the pressure roller 32 through the film 36, and a fixing nip portion N of about 6 mm is formed.

  Then, a rotational force is transmitted to the drive gear G of the pressure roller 32 from a drive mechanism (not shown), and the pressure roller 32 is rotationally driven in the counterclockwise direction in FIG. 1 at a predetermined speed. As the pressure roller 32 is driven to rotate, a rotational force acts on the film 36 by the frictional force between the pressure roller 32 and the film 36 in the fixing nip N. As a result, the inner surface of the film 36 is in close contact with the upper surface of the pressure holder 38 and slides, and the outer periphery of the pressure holder 38 is rotated by the rotation of the pressure roller 32 in the clockwise direction. Since the power supply member 37 is fixed to the pressure holder 38, the power supply member 37 contacts the rotating pressure roller 32 while sliding.

  The recording material P is introduced in a state in which the film 36 is rotated by the rotation of the pressure roller 32 and the heat generation pattern 36b is energized to increase the temperature of the film 36 to a predetermined temperature. The entrance guide 30 plays a role of guiding the recording material P so that the recording material P on which the toner image t in an unfixed state is placed is accurately guided to the fixing nip portion N. A recording material P carrying an unfixed toner image t is introduced between the film 36 of the fixing nip N and the pressure roller 32, and the toner image carrying side surface of the recording material P is placed on the outer surface of the film 36 in the fixing nip N. The fixing nip portion N is nipped and conveyed in close contact. In this nipping and conveying process, the recording material P is heated by the heat of the film 36 heated by the resistance heat generation of the heat generating pattern 36b, and the unfixed toner image t on the recording material P is heated and pressurized on the recording material P to be melted. It is fixed. The recording material P that has passed through the fixing nip portion N is ejected after being separated from the surface of the film 36 with a curvature, and is conveyed by a pair of ejection rollers (not shown).

  FIG. 5 is a schematic view showing the electrical connection of the fixing device. The power supply member 37a and the power supply member 37b at both ends are connected to a power source 50 by a conductive wire, and the power source 50 supplies power by a control unit (not shown). When power is supplied from the power supply members 37a and 37b to the heat generation pattern 36b through the base layer 36a, a current flows in the heat generation pattern 36b, and the film 36 is quickly heated by resistance heat generation. The temperature detecting means 42 measures the surface temperature of the film 36 in a non-contact manner, and in this embodiment, a thermopile is used and is arranged at a substantially central portion of the film 36 in the longitudinal direction. The surface temperature of the film 36 is detected by the temperature detecting means 42, and the power supply from the power source 50 to the film 36 is controlled by the control unit so that the temperature is maintained at a predetermined temperature.

  The region of the thin line portion (divided portion) of the heat generation pattern 36b is provided so as to be longer in the longitudinal direction than the maximum width of the recording material P. Thereby, while applying sufficient heat to the entire area of the recording material P, unnecessary heat generation is suppressed in the regions at both ends where the recording material P does not pass.

  Here, for example, as in the comparative example shown in FIG. 13, the heat generation pattern 36 b is formed on the insulating base layer 136 a, and power is supplied from a power supply member 37 disposed outside the film 36. Since the elastic layer 36c and the release layer 36d are insulative, in order to enable power supply to the heat generation pattern 36b, the elastic layer 36c and the release layer 36d are not provided at both ends, and the heat generation pattern 36b is exposed to expose the power supply member 37. Are in contact. In this case, only the thin line portion of the heat generation pattern 36b generates heat, and the region between the thin lines does not generate heat. Therefore, there is a problem that temperature unevenness occurs on the surface of the film 36, and as a result, uneven glossiness of the image due to uneven fixing property of the toner on the recording material P occurs.

  On the other hand, in the case where only the conductive base layer 36a is caused to generate resistance heat without using a heat generation pattern, there is a problem that it is difficult to reduce the resistance until resistance heat generation is possible. Further, as described later, there is a problem that abnormal heat generation occurs when a part of the film 36 is damaged.

Therefore, in the present embodiment, the heat generation pattern 36b is formed on the conductive base layer 36a. Hereinafter, the configuration of the film 36 and its effects in the present embodiment will be described in detail. The heat generation pattern 36b is formed on the conductive base layer 36a, and the resistance value of the heat generation pattern 36b is made lower than the resistance value of the base layer 36a. In this example, the surface resistivity of the heat generation pattern 36b is a measured value according to JIS K 7194 using Loresta GP (manufactured by Mitsubishi Chemical Analytech), and is 7.04 × 10 ⁻¹ Ω / □. is there. Since it is impossible to measure the resistance of the thin line-shaped heat generation pattern 36b on the base layer 36a, the measured value is obtained by forming the heat generation pattern on the insulator in a planar shape with the same thickness. On the other hand, the surface resistivity of the base layer 36a is 2.47 × 10Ω / □, and the resistance value of the heat generating pattern 36b is lower. Therefore, the current flowing from the power supply member 37 mainly flows through the heat generation pattern 36b and partly flows through the base layer 36a according to the resistance ratio. Since not only the heat generation pattern 36b but also the base layer 36a generates resistance heat, it is possible to suppress temperature unevenness between a portion where the heat generation pattern 36b is present and a portion where the heat generation pattern 36b is not present.

  FIG. 6 is a diagram showing temperature unevenness on the surface of the film 36 when the base layer 36a is conductive (this example) and when it is insulated (Comparative Example 1). In any case, although the temperature is high because the amount of heat generation is large in the heat generation pattern 36b portion, in this embodiment, the base layer 36a also generates heat, so that temperature unevenness can be suppressed.

On the other hand, as shown in FIG. 7A, when resistance heating is performed using only the conductive base layer 236a as a heating element without using a heat generation pattern, there is a problem that abnormal heat generation occurs at the time of breakage. This is a phenomenon in which when a breakage such as a crack occurs in a part of the film 36, a current that tries to bypass the crack is concentrated at the end of the crack, resulting in a higher temperature than the surroundings. Here, if the heat generating pattern 36b divided in the rotation direction of the film 36 is a heating element, as shown in FIG. 7B, even if a part of the film 36 is damaged, current concentration can be suppressed. Generation of fever can be suppressed. This is because even if a portion of the heat generation pattern 36b is cut due to breakage, the generation of a current that makes a detour is small.

表１ 抵抗比率による画像の光沢ムラとクラック端の異常発熱 Therefore, it is necessary to select an appropriate resistance ratio between the base layer 36a and the heat generation pattern 36b so as to suppress both “temperature unevenness on the surface of the film 36” and “abnormal heat generation when the film 36 is broken”. Table 1 below shows uneven glossiness of the image and abnormal heat generation at the crack edge when the resistance ratio between the heat generation pattern 36b and the base layer 36a (surface low efficiency of the heat generation pattern 36b / surface low efficiency of the base layer 36a) is changed. This is based on the simulation results.

Table 1 Image gloss unevenness and abnormal heat generation at the crack edge depending on the resistance ratio

  Both “image gloss unevenness due to temperature unevenness on the surface of the film 36” and “abnormal heat generation when the film 36 is broken” can be suppressed when the resistance ratio of the heat generation pattern 36b and the base layer 36a is in the range of 1/5 to 1/500. I understand. Therefore, the resistance ratio between the heat generating pattern 36b and the base layer 36a may be set in the range of 1/5 to 1/500, preferably 1/5 to 1/100. Therefore, in this embodiment, by setting the resistance ratio of the heat generation pattern 36b and the base layer 36a to about 1/35, both “image gloss unevenness due to temperature unevenness on the surface of the film 36” and “abnormal heat generation when the film 36 is damaged”. Control is possible.

  As described above, according to this embodiment, the heating element is provided on the conductive layer of the film, and the resistance of the heating element is made lower than the resistance of the conductive layer, so that most of the current flows through the heating element. In addition, since a part of current also flows through the conductive layer and heat is generated by resistance, temperature unevenness can be suppressed. Further, by causing most of the current to flow through the heating element divided in the circumferential direction, it is possible to suppress the occurrence of abnormal heat generation even when the film is broken.

[Example 2]
A second embodiment of the present invention will be described with reference to FIGS. FIG. 8 is a schematic cross-sectional view showing the main part of the fixing device 18 according to the present embodiment. FIG. 9 is a schematic front view of the fixing device 18 according to the present embodiment. FIG. 10 is a schematic perspective view showing the configuration of the fixing roller 62. FIG. 11 is a schematic cross-sectional view showing the layer configuration of the fixing roller 62. FIG. 12 is a schematic diagram showing electrical connection.

Unlike the film 36 of the first embodiment, this embodiment is different from the first embodiment in that it includes a fixing roller 62 and heats a heat generation pattern 62 d provided on the fixing roller 62. In the second embodiment, description of the same operation and configuration as in the first embodiment will be omitted, and only differences from the first embodiment will be described here. In this embodiment, as shown in FIGS. 8 and 9, the fixing roller 62 as a rotating body is on the upper side, and the pressure film assembly 61 as a pressing body is on the lower side to form a nip portion. Similar to the first embodiment, the electrode member 37 is formed by the pressure holder 3.
Although the electrode member 37 is provided outside the end portion of the pressure film 66, the electrode member 37 supplies power to the fixing roller 62 from the outer surface.

  The fixing roller 62 includes a cored bar 62a, a first elastic layer 62b, a conductive layer 62c, a heat generation pattern 62d, a second elastic layer 62e, and a release layer 62f, which are sequentially stacked. FIG. 10 is a perspective view showing the configuration of the cored bar 62a, the first elastic layer 62b, the conductive layer 62c, and the heat generation pattern 62d of the fixing roller. In the drawing, the second elastic layer 62e and a part of the release layer 62f are omitted for easy understanding of the configuration of the heat generation pattern 62d. 11 is a cross-sectional view showing the layer structure of the fixing roller 62. FIG. 11 (a) is a cross-sectional view of the end portion in the longitudinal direction of the fixing roller 62, and FIG. 11 (b) is a cross-sectional view of the central portion. Yes. The second elastic layer 62e and the release layer 62f are not formed at the end portions, but are formed only at the central portion. In addition, since each figure has shown the structure intelligibly, ratios, such as the width | variety and the space | interval of the heat generation pattern 62d, and the thickness of each layer, are not illustrated correctly.

  In this embodiment, a first elastic layer 62b of a silicone rubber layer having a thickness of about 3.5 mm is formed by injection molding on a cored bar 62a made of stainless steel and having an outer diameter of 11 mm. Then, a PI film conductive layer 62c in which carbon having a thickness of about 60 μm was dispersed was coated thereon, and a heat generation pattern 62d having a thickness of about 10 μm was formed thereon. Further, a second elastic layer 62e made of silicone rubber, fluorine rubber or the like having a thickness of about 200 μm is formed thereon, and a release layer 62f of a PFA coat layer having a thickness of about 40 μm is formed thereon as a top layer. 62 was used. The second elastic layer 62e plays a role of reducing the hardness in the vicinity of the surface of the fixing roller 62 to improve the fixing property and leveling the unevenness due to the heat generation pattern 62d to form a smooth surface. The outer diameter of the roller is about 18 mm. As in the first embodiment, the heat generation pattern 62d is formed by screen-printing silver ink.

  As shown in FIGS. 9 and 12, the second elastic layer 62e and the release layer 62f are not formed in the region of about 10 mm at both ends in the longitudinal direction of the fixing roller 62, and the heat generation pattern 62d is exposed. Yes. The power supply member 37 directly contacts the heat generation pattern 62d to supply power. The pressure film 66 is a flexible cylindrical member in which a release layer is formed on a base layer made of a heat-resistant resin and has flexibility. In this embodiment, a polyimide base material having a thickness of about 60 μm formed in a cylindrical shape is used as the base layer. On the base layer, a PFA resin tube having a thickness of about 15 μm was coated as a release layer. In this embodiment, the film 66 having an inner diameter of about 18 mm is used.

  Also in this embodiment, it is possible to suppress temperature unevenness by providing the heat generation pattern 62d on the conductive layer 62c and making the resistance of the heating element lower than the resistance of the conductive layer. Also, by causing most of the current to flow through the heating element divided in the circumferential direction, it is possible to suppress the occurrence of abnormal heat generation even when the fixing roller 62 is broken.

  In the present embodiment, the conductive layer 62c is filled with the first elastic layer 62b with respect to the first embodiment, so that there is an advantage that the film is less likely to be damaged than the film 36 of the first embodiment.

  As described above, the first and second embodiments have been described using the example in which the heat generation pattern is formed outside the conductive base layer. However, the order of the layer configuration is not limited as long as the heat generation pattern and the conductive base layer are in contact with each other. Accordingly, a configuration in which the heat generation pattern is formed inside the conductive base layer, or a configuration in which the heat generation pattern is embedded in the conductive base layer may be employed. In the first embodiment, the configuration in which power is supplied from the inner surface of the film 36 has been described. However, the configuration in which power is supplied from the outer surface as in the second embodiment may be used.

18, fixing device, 32, pressure roller (pressure body), 36, fixing film (rotary body), 36
a ... base layer (conductive layer), 36b ... heating pattern (heating element), 37 ... power feeding member

Claims (14)

In a fixing device comprising: a rotating body having a heating element; and a pressing body that presses against the rotating body to form a fixing nip portion;
The rotating body has a conductive layer in which the heating element is formed as an outer layer,
The heating element is formed on the conductive layer so as to be continuous over the entire circumference in the rotation direction of the rotating body, and is spaced from the cylindrical portion that receives power from a power supply member in the rotation direction on the conductive layer. A fixing unit.   The fixing device according to claim 1, wherein a surface resistivity of the heating element is lower than a surface resistivity of the conductive layer.   The fixing device according to claim 2, wherein a resistance ratio between the heating element and the conductive layer is 1/5 to 1/100.   The said division | segmentation part has the strip | belt-shaped part extended in the direction orthogonal to the said rotation direction from the said cylindrical part, and the multiple are formed in the circumferential direction at intervals. The fixing device described.   The fixing device according to claim 4, wherein the plurality of belt-shaped portions are formed on the conductive layer over the entire circumference in the rotation direction. The cylindrical portions are respectively provided at both ends in a direction orthogonal to the rotation direction on the conductive layer,
The fixing device according to claim 4, wherein the belt-shaped portion is formed so as to connect one of the cylindrical portions and the other cylindrical portion.   The belt-like portion is formed longer than the width of the recording material in a direction orthogonal to the conveyance direction of the recording material to be nipped and conveyed at the fixing nip portion. The fixing device according to 1.   The fixing device according to claim 1, wherein the heating element receives power from the power supply member via the conductive layer in the cylindrical portion.   The fixing device according to claim 8, wherein the rotating body is in contact with the power supply member on an inner surface of the conductive layer.   The fixing device according to claim 1, wherein the heating element is in contact with the power supply member in the cylindrical portion.   The fixing device according to claim 10, wherein the heating element is in contact with the power supply member on an outer surface of the cylindrical portion.   The fixing device according to claim 1, wherein the rotating body is a cylindrical film.   The fixing device according to claim 1, wherein the rotating body is a roller. An image forming unit for forming a developer image on a recording material;
An image forming apparatus comprising: the fixing device according to claim 1, which fixes a developer image on a recording material.

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