Fixing device and image forming apparatus equipped with same

Abstract

To provide a fixing device that can prevent overheat of a fixing belt, and an image forming apparatus including the same.SOLUTION: A fixing device 3 comprises: a rotatable endless fixing belt 30; a nip forming member 31 that is disposed on an inner peripheral surface of the fixing belt 30; a pressure roller 34 that is brought into press-contact against the nip forming member 31 from the outside of the fixing belt 30, and forms a fixing nip area FN between the fixing belt 30 and the pressure roller; and a heat source 33 that is disposed inside the fixing belt 30 and heats the fixing belt 30. The fixing device includes a heat conduction member 4 that is disposed on the outer peripheral side of the fixing belt 30, and the heat conduction member 4 extends over a width area in the direction of axis of rotation δ of the fixing belt 30.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fixing device and an image forming apparatus. [Background technology]

[0002] A known fixing device is one that presses a pressure roller against the outside of a rotatable, endless fixing belt, forms a fixing nip area between the fixing belt and the pressure roller, and heats the sheet in the fixing nip area to fix a toner image to the sheet (for example, Patent Document 1).

[0003] Such a fixing belt is heated by a heat source disposed inside the fixing belt. In recent years, from the viewpoint of energy conservation, there has been a demand for fixing belts with a lower heat capacity (faster heating). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2016-224200 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques have the problem that they are insufficient to prevent the fixing belt from being excessively heated by the heat source.

[0006] The present invention has been made to solve the above-mentioned problems of the conventional art, and has an object to provide a fixing device that can prevent the fixing belt from overheating, and an image forming apparatus equipped with the same. [Means for solving the problem]

[0007] In order to achieve the above-mentioned object, the fixing device described in the present application comprises a rotatable endless fixing belt, a nip forming member arranged on the inner surface of the fixing belt, a pressure roller that is pressed against the nip forming member from the outside of the fixing belt to form a fixing nip area between the fixing belt and the pressure roller, and a heat source that is arranged inside the fixing belt and heats the fixing belt, and is characterized in that it comprises a heat conductive member arranged on the outer lateral side of the fixing belt, and the heat conductive member extends across the width area in the direction of the rotation axis of the fixing belt.

[0008] In the fixing device, the heat conducting member may be disposed on or in the vicinity of an extension of an imaginary line connecting the heat source and the fixing belt at the shortest distance.

[0009] In addition, in the fixing device, the heat conduction member may be arranged on or in the vicinity of an imaginary line connecting the heat source and the fixing belt at the shortest distance at any position in the direction of the rotation axis of the fixing belt.

[0010] In addition, the fixing device may further include a thermostat that cuts off the power supply to the heat source when the temperature of the fixing belt reaches a predetermined temperature, the heat conduction member may have an opening, and the thermostat may be located in a position facing the opening.

[0011] In the fixing device, the thermostat may be provided on or in the vicinity of an extension of an imaginary line connecting the heat source and the fixing belt at the shortest distance.

[0012] In the fixing device, the heat conducting member may be made up of a plurality of members made of different materials.

[0013] The fixing device may further include a fixing frame that rotatably supports both ends of the fixing belt, the fixing frame having a plate arranged along the rotation axis direction of the fixing belt, and the heat conduction member being arranged between the fixing belt and the plate.

[0014] In the fixing device, the heat conducting member may be integrally formed with the fixing frame.

[0015] The fixing device may further include a fixing frame that rotatably supports both ends of the fixing belt, the fixing frame having a plate arranged on the outer circumferential side of the fixing belt, the plate of the fixing frame extending across the width region in the direction of the rotation axis of the fixing belt and functioning as the heat conduction member.

[0016] The fixing device may further include a fixing frame that rotatably supports both ends of the fixing belt, the fixing frame having a plate arranged along the rotation axis direction of the fixing belt, and the thermal conductivity of the heat conduction member being higher than the thermal conductivity of the frame.

[0017] The image forming apparatus described in the present application is characterized by including the fixing device. [Effects of the Invention]

[0018] According to the present invention, it is possible to prevent the fixing belt from overheating. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view of an image forming apparatus according to a first embodiment, as viewed from the front. [Figure 2] 1 is a schematic cross-sectional view of a fixing device according to a first embodiment, as viewed from the front. [Figure 3] 3 is a schematic side view showing a part of the fixing device of FIG. 2. [Figure 4]FIG. 2 is a schematic side view showing a fixing frame and a heat conducting member. [Figure 5] FIG. 2 is a schematic cross-sectional view showing an enlarged view of a fixing belt and its surroundings. [Figure 6] FIG. 10 is a schematic cross-sectional view of a fixing device according to a second embodiment, as viewed from the front. [Figure 7] FIG. 11 is a schematic cross-sectional view of a fixing device according to a third embodiment, as viewed from the front. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same components in the embodiments described below will be designated by the same reference numerals, and redundant descriptions of those components will be omitted.

[0021] (Embodiment 1) -Image forming device- First, the configuration of the image forming apparatus A in the first embodiment will be described.

[0022] 1 is a schematic cross-sectional view of an image forming apparatus A in embodiment 1 as viewed from the front. In the figure, the symbol X indicates the front-to-rear direction (depth direction) of the image forming apparatus A, the symbol Y indicates the left-to-right direction of the image forming apparatus A, and the symbol Z indicates the up-to-down direction of the image forming apparatus A. These settings are the same in the following embodiments.

[0023] The image forming apparatus A is an image forming apparatus that forms a monochrome image on a sheet by electrophotography in accordance with image data read by an image reading device 25 or image data transmitted from an external device.

[0024] The image forming apparatus A includes a document feeder 10 and an image forming apparatus main body 11 (see FIG. 1). The image forming apparatus main body 11 includes an image forming section 12 and a paper transport system 20.

[0025] The image forming unit 12 includes an exposure device 13, a developing device 14, an image carrier 15, a cleaner unit 16, a charger 17, a transfer unit 18, a toner cartridge device 19, and a fixing device 3 (see FIG. 1). The transfer unit 18 has a transfer roller 18a. A transfer bias is applied to the transfer roller 18a, so that the toner image formed on the image carrier 15 is transferred to a sheet. The configuration of the fixing device 3 will be described in detail later.

[0026] The paper transport system 20 includes a paper feed tray 21, a manual paper feed tray 22, a discharge tray 23, and transport rollers (not shown) provided along the sheet transport path S.

[0027] An original document table 24 made of transparent glass on which an original document is placed is provided at the top of the image forming apparatus main body 11, and an image reading device 25 for reading an image of the original document is provided below the original document table 24. An original document feeder 10 is provided above the original document table 24. The image of the original document read by the image reading device 25 is sent to the image forming apparatus main body 11 as image data, and an image formed based on the image data in the image forming apparatus main body 11 is recorded on a sheet.

[0028] The image forming apparatus A described above is configured to print an image on a sheet as follows. First, a sheet is supplied from the paper feed tray 21 or the manual paper feed tray 22. The sheet is transported to the transfer unit 18 by a transport roller. Next, the toner image formed by the image forming unit 12 is transferred onto the sheet by the transfer unit 18. Thereafter, the unfixed toner on the sheet is melted and fixed by heat by the fixing device 3, and the sheet is discharged onto the discharge tray 23 by the transport roller and discharge roller (not shown). In this way, a series of printing operations by the image forming apparatus A is completed.

[0029] The image forming apparatus A may be a color image forming apparatus. In this case, image forming units 12 may be provided for each of a plurality of colors (for example, black (K), cyan (C), magenta (M), and yellow (Y)), and the toner images formed by these image forming units 12 may be transferred onto a primary transfer belt in a sequentially overlapping manner.

[0030] - Fixing device - Next, the fixing device 3 will be described.

[0031] Fig. 2 is a schematic cross-sectional view of the fixing device 3 in embodiment 1 as seen from the front. Fig. 3 is a schematic side view showing a part of the fixing device 3. In Fig. 3, the nip forming member 31, the support member 32, and the heat source 33 inside the fixing belt 30 are not shown. In Figs. 3 and 4, the thickness of the fixing frame 36 and the heat conduction member 4, which will be described later, are not shown.

[0032] In this embodiment, the fixing device 3 includes a fixing belt 30, a nip forming member 31, a support member 32, a heat source 33, a pressure roller 34, a peeling member 35, a fixing frame 36, and a thermostat 37 (see FIG. 2).

[0033] The fixing belt 30 is an endless (cylindrical) heat-resistant belt having a width in a width direction W perpendicular to the sheet conveying direction F, and is provided to be rotatable around a rotation axis δ along the width direction W (see FIGS. 2 and 3). In this embodiment, the width direction W of the fixing belt 30 is aligned with the front-rear direction X of the image forming apparatus A. Both ends of the fixing belt 30 are supported by a fixing frame 36 via a pair of holders 300 that abut against the inner circumferential surface of the fixing belt 30 and hold both ends of the fixing belt 30.

[0034] The fixing belt 30 is composed of a base material made of a metal such as nickel and having a predetermined thickness (for example, about 30 μm to 100 μm), and a resin layer and a surface layer (release layer) provided on the base material and made of silicone rubber or a PFA tube and having a predetermined thickness (for example, about 100 μm to 300 μm). The width of the fixing belt 30 is set to, for example, about 340 mm to 360 mm. The inner diameter of the fixing belt 30 is set to, for example, about 30 mm. The fixing belt 30 is heated by a heat source 33 to a predetermined fixing temperature (for example, 200°C to 250°C).

[0035] The nip forming member 31 is disposed on the inner peripheral surface of the fixing belt 30 to form a fixing nip area FN between the fixing belt 30 and the pressure roller 34 (see FIG. 2). The nip forming member 31 is formed in the shape of a long plate extending along the rotation axis δ of the fixing belt 30. The nip forming member 31 is formed, for example, from a highly rigid, heat-resistant resin material (e.g., liquid crystal polymer (LCP), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), etc.) or a highly elastic, heat-resistant resin material (e.g., rubber material). The length of the nip forming member 31 is set to be approximately the same as the width of the fixing belt 30.

[0036] A sliding sheet 310 is provided between the nip forming member 31 and the fixing belt 30 to reduce sliding resistance between the nip forming member 31 and the fixing belt 30 (see FIG. 2). The sliding sheet 310 is adhered to the nip forming member 31 with an adhesive or an adhesive member. The sliding sheet 310 is formed, for example, from a glass fiber material (for example, glass cloth) coated with a fluororesin such as PTFE (Polytetrafluoroethylene) (for example, a glass cloth sheet). The thickness of the sliding sheet 310 is set to, for example, about 0.1 mm to 0.5 mm.

[0037] The support member 32 supports the nip forming member 31 while pressing it against the inner circumferential surface of the fixing belt 30, and is T-shaped in cross section as viewed from the direction of the rotation axis δ of the fixing belt 30, and is provided along the rotation axis δ of the fixing belt 30 (see FIG. 2). The nip forming member 31 is fixed to the bottom surface of the support member 32. Both ends of the support member 32 are supported by the fixing frame 36.

[0038] The heat source 33 heats the fixing belt 30 and is disposed inside the fixing belt 30 (see FIG. 2). The heat source 33 is, for example, a lamp heater such as a halogen lamp. The heat source 33 is controlled by a control unit (not shown). The length of the heat source 33 is set to be approximately the same as the width of the fixing belt 30.

[0039] The pressure roller 34 is pressed against the nip forming member 31 from the outside of the fixing belt 30 to form a fixing nip area FN between itself and the fixing belt 30, and is disposed opposite the nip forming member 31 across the fixing belt 30. The pressure roller 34 is rotatably supported by a pressure frame (not shown) and is driven to rotate by a drive source (not shown) such as a motor. The pressure roller 34 is composed of a cylindrical core made of a metal such as aluminum and an elastic material such as rubber that covers the surface of the core. The pressure roller 34 is driven to rotate by the drive source and comes into contact with the fixing belt 30, thereby forming the fixing nip area FN and transmitting a driving force to the fixing belt 30 via the nip forming member 31, causing the fixing belt 30 to rotate.

[0040] The peeling member 35 peels off the sheet that has passed between the fixing belt 30 and the pressure roller 34 from the fixing belt 30, and is provided downstream of the fixing belt 30 in the sheet conveying direction F (see FIG. 2). The peeling member 35 prevents the sheet that has passed between the fixing belt 30 and the pressure roller 34 from getting wrapped around the fixing belt 30.

[0041] FIG. 4 is a schematic side view showing the fixing frame 36 and the heat conducting member 4. As shown in FIG.

[0042] The fixing frame 36 rotatably supports both ends of the fixing belt 30 and includes a main plate 360 disposed along the direction of the rotation axis δ of the fixing belt 30 and a pair of holding plates 361 facing each other at both ends of the main plate 360 (see FIGS. 3 and 4). The main plate 360 corresponds to the "plate" recited in the claims. In this embodiment, the main plate 360 is bent so as to cover the outer periphery of the fixing belt 30 (see FIG. 2). The main plate 360 has mounting portions 362 and 363 at its lower end to which the thermostat 37 is attached (see FIG. 4). The pair of holding plates 361 are fixed to the main plate 360 with fastening members (not shown) such as screws.

[0043] The thermostat 37 cuts off the power supply to the heat source 33 when the temperature of the fixing belt 30 reaches a predetermined temperature. Specifically, the thermostat 37 is electrically connected to a power line (not shown) that supplies power to the heat source 33, and when the temperature reaches a predetermined reaction temperature (operating temperature, rated temperature) (e.g., 190°C), it directly cuts off the power supply to the heat source 33 to protect the fixing belt 30. The thermostat 37 is made up of a thermostat 37a provided on a mounting portion 362 at the end of the main plate 360 of the fixing frame 36 in the direction of the rotation axis δ of the fixing belt 30, and a thermostat 37b provided on a mounting portion 363 that is more inward than the mounting portion 362 in the direction of the rotation axis δ of the fixing belt 30.

[0044] The mounting portions 362 and 363 of the main plate 360 bulge toward the fixing belt 30. This allows the thermostats 37a and 37b to be located close to the area of the fixing belt 30 that is closest to the heat source 33 and has the highest temperature.

[0045] In the fixing device 3 described above, it is necessary to prevent the fixing belt 30 from being excessively heated by the heat source 33. Therefore, in addition to the above configuration, the fixing device 3 is provided with a heat conductive member 4 disposed on the outer circumferential side of the fixing belt 30 (see FIGS. 2 to 4). The heat conductive member 4 will be described below.

[0046] 5 is a schematic cross-sectional view showing an enlarged view of the fixing belt 30 and its surroundings. In FIG. 5, curved arrows conceptually indicate the movement of heat.

[0047] In this embodiment, the heat conducting member 4 is disposed between the fixing belt 30 and the main plate 360 of the fixing frame 36, and extends across the width of the fixing belt 30 in the direction of the rotation axis δ (see FIGS. 2 to 4). Here, "extending across the width" refers not only to the case where the heat conducting member 4 has the same width as the fixing belt 30, but also to the case where the heat conducting member 4 has a width roughly similar to that of the fixing belt 30. The heat conducting member 4 is formed from a metal plate having a predetermined thickness (for example, about 0.5 mm).

[0048] The heat conduction member 4 has a curved portion 40 that curves along the outer peripheral surface of the fixing belt 30 in a cross-sectional view taken from the direction of the rotation axis δ of the fixing belt 30, a fixed portion 41 that is connected to the upper edge of the curved portion 40 and fixed to the main plate 360 of the fixing frame 36, and an opening 42 that opens toward the fixing belt 30 at the lower end of the curved portion 40 (see Figures 2 and 4).

[0049] The curved portion 40 is spaced a predetermined distance (for example, about 3 mm) from the outer peripheral surface of the fixing belt 30. At the center of the curved portion 40, through-holes 43 and 44 are formed to expose temperature sensors (not shown) that measure the temperature of the outer surface of the fixing belt 30 in a non-contact manner.

[0050] The fixed portion 41 is fixed to the main plate 360 of the fixing frame 36 by a fastening member B such as a screw.

[0051] The opening 42 is composed of openings 42a and 42b recessed into the lower edge of the curved portion 40 corresponding to the thermostats 37a and 37b, respectively. The thermostats 37a and 37b are provided at positions facing the openings 42a and 42b, respectively. This allows the thermostats 37a and 37b to operate accurately in response to the temperature of the fixing belt 30. The thermostat 37a facing the opening 42a is disposed on an extension of the imaginary line L that connects the heat source 33 and the fixing belt 30 in the shortest distance (see FIG. 2). This allows the thermostat 37a to be located close to the area of the fixing belt 30 that is closest to the heat source 33 and therefore has the highest temperature, allowing the thermostat 37a to be operated accurately in response to the temperature of the fixing belt 30. Even if the thermostat 37a is disposed near the extension of the virtual straight line L, the thermostat 37a can be operated accurately in accordance with the temperature of the fixing belt 30 in the same manner as described above.

[0052] As shown in FIG. 5 , the heat of the fixing belt 30 generated by the heat source 33 is transferred to the curved portion 40 of the heat conductive member 4 via the air around the outer periphery of the fixing belt 30. Here, the heat of the fixing belt 30 includes not only the heat accumulated in the fixing belt 30 but also the heat stagnating near the outer surface of the fixing belt 30. In addition, because the heat conductive member 4 extends across the width of the fixing belt 30 in the direction of the rotation axis δ, the transfer of heat from the fixing belt 30 to the heat conductive member 4 is promoted across the width of the fixing belt 30 in the direction of the rotation axis δ, as shown in FIG. 5 . As a result, the heat of the fixing belt 30 is absorbed by the heat conductive member 4 across the entire width of the fixing belt 30 in the direction of the rotation axis δ, thereby preventing the fixing belt 30 from overheating.

[0053] Preventing the fuser belt 30 from overheating helps achieve the purpose of the thermostat 37 , which is to protect the fuser belt 30 .

[0054] Furthermore, in this embodiment, the heat conduction member 4 (specifically, the curved portion 40) is disposed near an extension of an imaginary straight line L that connects the heat source 33 and the fixing belt 30 over the shortest distance (see FIG. 2). This allows the heat conduction member 4 to absorb the heat of the area of the fixing belt 30 that is closest to the heat source 33 and therefore has the highest temperature, thereby efficiently preventing overheating of the fixing belt 30. Note that even if the heat conduction member 4 is disposed on an extension of the imaginary straight line L, overheating of the fixing belt 30 can be efficiently prevented in the same manner as described above.

[0055] In this embodiment, the heat conductive member 4 is disposed on an imaginary line P that connects the heat source 33 and the fixing belt 30 at the shortest distance at any position in the direction of the rotation axis δ of the fixing belt 30 (see FIG. 4). In other words, the imaginary line P indicates a portion of the heat conductive member 4 that is closest to the heat source 33. This allows the heat conductive member 4 to absorb the heat of the region that becomes hot near the heat source 33 across the entire width of the fixing belt 30 in the direction of the rotation axis δ, thereby efficiently preventing overheating of the fixing belt 30. Note that even if the heat conductive member 4 is disposed near the imaginary line P, overheating of the fixing belt 30 can be efficiently prevented in the same manner as described above.

[0056] Furthermore, in this embodiment, as described above, the heat conductive member 4 is disposed between the fixing belt 30 and the main plate 360 of the fixing frame 36. In other words, the heat conductive member 4 is closer to the fixing belt 30 than the main plate 360. This allows the heat of the fixing belt 30 to be preferentially transferred to the heat conductive member 4 rather than the main plate 360. This allows the heat conductive member 4 to efficiently prevent the fixing belt 30 from overheating. Furthermore, as described above, the heat conductive member 4 is disposed between the fixing belt 30 and the main plate 360 of the fixing frame 36. This also provides the additional benefit of making effective use of the space between the fixing belt 30 and the fixing frame 36.

[0057] Furthermore, since the essential function of the heat conduction member 4 is to absorb the heat of the fixing belt 30 through the air on the outer lateral side of the fixing belt 30 and prevent overheating of the fixing belt 30, the material is not limited to metal, and any material having a higher thermal conductivity than air may be used, for example, a resin material containing a metal filler. Of course, if a material with excellent thermal conductivity, such as aluminum or copper, is used for the heat conduction member 4, overheating of the fixing belt 30 can be efficiently prevented.

[0058] Moreover, the heat conducting member 4 may be formed integrally with the fixing frame 36. This reduces the number of parts in the fixing device 3, thereby reducing costs.

[0059] (Embodiment 2) Hereinafter, only the differences between the second embodiment and the first embodiment will be described.

[0060] FIG. 6 is a schematic cross-sectional view of the fixing device 3 according to the second embodiment, as viewed from the front.

[0061] In the second embodiment, the thermal conduction member 4 is composed of a first thermal conduction plate 4a and a second thermal conduction plate 4b made of different materials (see FIG. 6). The first thermal conduction plate 4a is fixed to the main plate 360 of the fixing frame 36. The second thermal conduction plate 4b is connected to the lower end of the first thermal conduction plate 4a with fastening members (not shown), such as screws, and is curved to fit the outer peripheral surface of the region of the fixing belt 30 that is closest to the heat source 33. The first thermal conduction plate 4a is made of, for example, an aluminum alloy. The second thermal conduction plate 4b, which is closer to the heat source 33 than the first thermal conduction plate 4a, is made of a material with better thermal conductivity than the first thermal conduction plate 4a, such as copper. That is, the second thermal conduction plate 4b efficiently absorbs heat from the region of the fixing belt 30 that is closer to the heat source 33 and therefore has a higher temperature than the other regions. Therefore, overheating of the fixing belt 30 can be more efficiently prevented than in the first embodiment. In this way, the heat conduction member 4 is made up of a plurality of members (first heat conduction plate 4a and second heat conduction plate 4b) made of different materials, which improves the degree of freedom in design.

[0062] (Embodiment 3) Hereinafter, only the differences between the third embodiment and the first embodiment will be described.

[0063] 7 is a schematic cross-sectional view of the fixing device 3 in embodiment 3 as seen from the front. In FIG. 7, the rotation axis δ is omitted.

[0064] In the third embodiment, the main plate 360 of the fixing frame 36 is disposed on the outer circumferential side of the fixing belt 30 and is formed closer to the fixing belt 30 than the main plate 360 in the first embodiment (see FIG. 7). The main plate 360 also extends across the width of the fixing belt 30 in the direction of the rotation axis δ.

[0065] In the third embodiment, the main plate 360 functions as the heat conducting member 4 in the first embodiment. That is, similar to the case where the heat conducting member 4 in the first embodiment is used, the transfer of heat from the fixing belt 30 to the main plate 360 is promoted across the width of the fixing belt 30 in the direction of the rotation axis δ, and the heat of the fixing belt 30 is absorbed by the main plate 360 across the entire width of the fixing belt 30 in the direction of the rotation axis δ. As a result, while the effect of preventing overheating of the fixing belt 30 is achieved, the number of parts of the fixing device 3 can be reduced, thereby reducing costs, compared to the above-described embodiments.

[0066] (Embodiment 4) In the fourth embodiment, the heat conducting member 4 is made of iron. The main plate 360 of the fixing frame 36 is made of stainless steel. That is, the thermal conductivity of the heat conducting member 4 (approximately 80 W / m K) is higher than the thermal conductivity of the main plate 360 (approximately 16 W / m K).

[0067] Therefore, even if the heat conductive member 4 and the main plate 360 are spaced apart from the outer circumferential surface of the fixing belt 30 by an equal distance, unlike the structure in the first embodiment in which the heat conductive member 4 is closer to the fixing belt 30 than the main plate 360, the heat of the fixing belt 30 will preferentially transfer to the heat conductive member 4, which has better thermal conductivity than the main plate 360. This allows the heat conductive member 4 to efficiently prevent the fixing belt 30 from overheating.

[0068] The above-described embodiments and examples are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments and examples, but should be defined based on the claims. Furthermore, all modifications within the meaning and scope of the claims are included. [Explanation of symbols]

[0069] A Image forming device 3 Fixing device 30 Fixing belt 31 Nip forming member 32 Support member 33 Heat source 34 Pressure roller 35 Peeling member 36 Fixing Frame 37 Thermostat 4. Heat conduction material 40 curved section 41 Fixed part 42 Opening 360 Main Plate 361 Retaining Plate F Conveying direction FN Fixing nip area δ rotation axis

Claims

1. a rotatable endless fixing belt; a nip forming member disposed on an inner circumferential surface of the fixing belt; a pressure roller that is pressed against the nip forming member from the outside of the fixing belt to form a fixing nip area between the fixing belt and the pressure roller; a heat source disposed inside the fixing belt and configured to heat the fixing belt; a fixing frame that rotatably supports both ends of the fixing belt; A fixing device comprising: a heat conducting member disposed on the outer circumferential side of the fixing belt; the heat conduction member extends across a width region of the fixing belt in a rotation axis direction, the fixing frame has a plate disposed on the outer circumferential side of the fixing belt, The plate of the fixing frame extends across a width region in the direction of the rotation axis of the fixing belt and functions as the heat conducting member. A fixing device characterized by:

2. 2. The fixing device according to claim 1, The fixing device is characterized in that the heat conducting member is disposed on or in the vicinity of an extension of an imaginary line connecting the heat source and the fixing belt at the shortest distance.

3. 3. The fixing device according to claim 2, A fixing device characterized in that the heat conduction member is arranged on or in the vicinity of an imaginary line connecting the heat source and the fixing belt at the shortest distance at any position in the direction of the rotation axis of the fixing belt.

4. 4. The fixing device according to claim 1, a thermostat that cuts off the power supply to the heat source when the temperature of the fixing belt reaches a predetermined temperature; the heat conducting member has an opening, The fixing device is characterized in that the thermostat is provided at a position facing the opening.

5. 5. The fixing device according to claim 4, The fixing device is characterized in that the thermostat is provided on or in the vicinity of an extension of an imaginary line connecting the heat source and the fixing belt at the shortest distance.

6. 6. The fixing device according to claim 1, The fixing device is characterized in that the heat conductive member is made up of a plurality of members made of different materials.

7. 7. An image forming apparatus comprising the fixing device according to claim 1.

Images