Nip forming unit and image forming device

Abstract

The present invention relates to a clamping portion forming unit and an image forming device that optimize the interval between a fixing belt and a separation component with a simple structure. The unit is characterized in that it includes: a rotatable flexible endless belt (fixing belt (20)); a clamping portion forming component (heater (22)) configured to be in contact with the inner peripheral surface of the endless belt; a pressure member (pressure roller (21)) that forms a clamping portion by pressing the endless belt and the clamping portion forming component, and a guide member (flange (400)) that guides both ends of the endless belt, and a conveyed body is conveyed through the clamping portion, and has a separation member (separation plate (310)) that separates the conveyed body that has passed through the clamping portion from the endless belt, the separation member having a non-contact portion (front end portion (311)) that does not contact the endless belt, and a contact portion (313) that keeps the interval between the non-contact portion and the endless belt at a specified size by contacting the endless belt.

Description

Technical Field

[0001] The present invention relates to a nip forming unit having a separation member for separating a transported object passing through a nip from an endless belt, and an image forming apparatus having the nip forming unit. Background Art

[0002] In image forming devices such as copiers and printers, a belt-type fixing device using an endless belt is known as a fixing device for fixing an image formed on a recording medium such as paper (for example, refer to Patent Document 1: Japanese Patent Gazette No. 2015-011167).

[0003] The fixing device disclosed in Patent Document 1 separates paper from the fixing belt by means of a paper separation plate disposed close to the fixing belt. When the paper separation plate is used in this way, if the interval between the fixing belt and the paper separation plate is too small, the paper separation plate is likely to contact the fixing belt and damage the belt, which causes abnormal images.

[0004] In addition, if the gap between the fixing belt and the paper separation plate is too large, the paper passes through the large gap and wraps around the fixing belt, which easily causes a paper jam. Therefore, it is necessary to make the paper separation plate as close to the fixing belt as possible without contacting the fixing belt.

[0005] The fixing device of Patent Document 1 optimizes the above-mentioned interval by a separation plate moving mechanism, but the separation plate moving mechanism has a complex structure and high cost due to a driving part and various sensors for driving the separation plate. Therefore, an object of the present invention is to optimize the interval between the endless belt and the separation member with a simple structure, thereby improving the separation of the conveyed object from the endless belt.

[0006] [Patent Document 1] (Japanese) Patent Publication No. 2015-011167 Summary of the invention

[0007] In order to solve the above-mentioned problems, the present invention relates to a clamping portion forming unit, characterized in that it includes: a rotatable flexible annular belt; a clamping portion forming component configured to be able to contact the inner circumferential surface of the annular belt; a pressure applying component that forms the clamping portion by crimping the annular belt and the clamping portion forming component, and a guiding component that guides the two ends of the annular belt, and the conveyed body is conveyed through the clamping portion, and has a separation component that separates the conveyed body that has passed through the clamping portion from the annular belt, the separation component having a non-contact portion that does not contact the annular belt, and a contact portion that maintains the interval between the non-contact portion and the annular belt to a specified size by contacting the annular belt.

[0008] According to the present invention, the interval between the endless belt and the separation member can be optimized, thereby improving the separation performance of the conveyed object from the endless belt. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 FIG. 2 is a diagram schematically showing the configuration of an image forming apparatus according to an embodiment of the present invention.

[0010] Figure 2 The figure shows the schematic structure of the fixing device.

[0011] Figure 3 Shown is a perspective view of a heater, a heater holder, and a guide member.

[0012] Figure 4 Shown is a top view of the heater.

[0013] Figure 5 Shown is a schematic diagram of the power supply circuit to the heater.

[0014] Figure 6 Shown is a flow chart of the control action of the heater.

[0015] Fig. 7A The figure shows a conceptual diagram of a fixing device having a paper separation mechanism.

[0016] Figure 7Ba Shown is a top view of the paper separation mechanism.

[0017] Figure 7Bb Shown is a top view of the paper separation mechanism.

[0018] Figure 7Bc FIG. 1 is a top view of a state where a separation plate of a paper separation mechanism is deformed.

[0019] Figure 7Bd FIG. 1 is a perspective view showing a state where a separation plate of a paper separation mechanism is deformed.

[0020] Figure 7Be FIG. 1 is a top view of a state where a separation plate of a paper separation mechanism is deformed.

[0021] Figure 7C The diagram shows a method of applying tension to the fixing belt by holding the flanges at both ends of the belt.

[0022] Fig.7D Shown is a diagram showing the positional relationship between the flange and the heater holder.

[0023] Fig. 8A Shown is a side view of the paper separation mechanism.

[0024] Figure 8B Shown is a side view of the paper separation mechanism with the tension spring installed.

[0025] Figure 8C Shown is an exploded perspective view of the paper separation mechanism.

[0026] Fig. 9A Shown is a side view of a fixing device having a paper separation mechanism.

[0027] Fig. 9B Shown is a side view of the fixing unit in a state where a paper jam occurs.

[0028] Fig. 9C The figure is a side view of the fixing device in a state where a sheet of paper is pulled out.

[0029] Fig.9D The figure shows a side view of the fixing device when the fixing belt is moved by releasing the pressure.

[0030] Fig.10 FIG. 1 is a top view of the fixing device for explaining the amount of pressure relief of the fixing belt.

[0031] Fig.11A Shown is a perspective view of the fixing device.

[0032] Fig. 11B The figure is a perspective view of one end portion cut out from the fixing belt.

[0033] Fig. 11C The figure shows an expanded top view of one end portion cut out from the fixing belt.

[0034] Fig. 12A Shown is a side view of the slack of the fuser belt.

[0035] Fig. 12B Shown is a side view of the slack of the fuser belt.

[0036] Fig.13 (a) and (b) are side views showing a method for measuring the relaxation rate of the fixing belt.

[0037] Fig.14 FIG. 1 is a side cross-sectional view showing a schematic structure of a fixing device according to another embodiment of the present invention.

[0038] Fig.15 Shown is a three-dimensional view of a heater, a first high thermal conductivity component, and a heater holder.

[0039] Fig.16 Shown is a top view of a heater with a first highly thermally conductive component configured.

[0040] Fig.17 Shown is with Fig.14 A side cross-sectional view showing a schematic structure of a fixing device according to a different embodiment.

[0041] Fig.18 Shown is a perspective view of a heater, a first high thermal conductivity component, a second high thermal conductivity component, and a heater holder.

[0042] Fig.19 FIG. 1 is a top view of a heater including a first high thermal conductivity component and a second high thermal conductivity component.

[0043] Fig. 20 Shown is the configuration of the second most thermally conductive component with Fig.15 Top view of different heaters.

[0044] Fig.21 Shown is with Fig.14 , Fig.17 A side cross-sectional view showing a schematic structure of a fixing device according to a different embodiment.

[0045] Fig. 22 FIG. 1 is a top view of a heater showing another example of the arrangement of the first highly thermally conductive member.

[0046] Fig.23 FIG. 1 is a top view of a heater showing another different example of the configuration of the first high thermal conductivity component.

[0047] Fig.24 Shown is a top view of the heater with the segmented area enlarged.

[0048] Fig.25 FIG. 1 is a schematic diagram showing a structure of a fixing device different from that of the above-mentioned embodiment.

[0049] Fig.26 Shown is Fig.25 A three-dimensional view of a heater, a first high thermal conductive component, a second high thermal conductive component, and a heater holder.

[0050] Fig. 27 FIG. 1 is a top view of a heater including a first high thermal conductivity component and a second high thermal conductivity component.

[0051] Fig.28 FIG. 1 is a top view of a heater showing another example of the arrangement of the first highly thermally conductive member and the second highly thermally conductive member.

[0052] Fig.29 FIG. 1 is a top view of a heater showing another different example of the configuration of the second high thermal conductivity member.

[0053] Fig.30 FIG. 1 is a schematic diagram showing a structure of a fixing device different from that of the above-mentioned embodiment.

[0054] Fig.31 Shown is a schematic diagram of the atomic crystal structure of graphene.

[0055] Fig.32Shown is a schematic diagram of the atomic crystal structure of graphite.

[0056] Fig.33 FIG. 1 is a side cross-sectional view of a fixing device showing a modified example of the arrangement of the thermistor.

[0057] Fig.34 FIG. 1 is a side sectional view showing a schematic structure of a fixing device different from the above-mentioned one.

[0058] Fig.35 FIG. 1 is a side sectional view showing a schematic structure of a fixing device different from the above-mentioned one.

[0059] Fig.36 FIG. 1 is a side sectional view showing a schematic structure of a fixing device different from the above-mentioned one.

[0060] Fig.37 Shown is with Figure 1 A schematic diagram of the structure of a different image forming apparatus.

[0061] Fig.38 FIG. 1 is a side cross-sectional view showing a schematic structure of a fixing device according to a first embodiment of the present invention.

[0062] Fig.39 Shown is Fig.17 A top view of a heater in a fixing device of FIG.

[0063] Fig.40 Shown is a perspective view of the heater and heater holder.

[0064] Fig.41 Shown is a perspective view of the connector installed relative to the heater.

[0065] Fig.42 Shown is a schematic diagram of the thermistor and thermostat configuration.

[0066] Fig.43 Shown is a schematic diagram of the groove portion of the flange. DETAILED DESCRIPTION

[0067] In the drawings for explaining the present invention, components or components having the same function or shape are given the same reference numerals and their re-explanation is omitted after the components are explained once, as long as they can be distinguished.

[0068] (●Image forming device) Figure 1 FIG. 1 is a diagram schematically showing the configuration of an image forming apparatus according to an embodiment of the present invention. Figure 1 The image forming apparatus 100 shown in the figure has four imaging units 1Y, 1M, 1C, and 1Bk which are attachable to and detachable from a main body of the image forming apparatus.

[0069] Each of the imaging units 1Y, 1M, 1C, and 1Bk has the same structure except that it contains different color developers such as yellow, magenta, cyan, and black corresponding to the color separation components of the color image. Specifically, each of the imaging units 1Y, 1M, 1C, and 1Bk includes a drum-shaped photoreceptor 2 as an image carrier, a charging device 3 for charging the surface of the photoreceptor 2, a developing device 4 for supplying a toner as a developer to the surface of the photoreceptor 2 to form a toner image, and a cleaning device 5 for cleaning the surface of the photoreceptor 2.

[0070] The image forming apparatus 100 includes an exposure device 6 for exposing the surface of each photoreceptor 2 to form an electrostatic latent image, a paper feeding device 7 for feeding paper P as a transported body and a recording medium, a transfer device 8 for transferring the toner image formed on each photoreceptor 2 to the paper P, a fixing device 9 as a nip forming unit for fixing the toner image transferred to the paper P, and a paper discharge device 10 for discharging the paper P to the outside of the apparatus. The recording medium includes thick paper, postcards, envelopes, thin paper, coated paper (coated paper or coated paper, etc.), tracing paper, OHP sheets, etc., in addition to the paper P (plain paper).

[0071] The transfer device 8 includes an endless intermediate transfer belt 11 as an intermediate transfer body stretched by a plurality of rollers, four primary transfer rollers 12 as primary transfer members for transferring the toner images on the photosensitive bodies 2 to the intermediate transfer belt 11, and secondary transfer rollers 13 as secondary transfer members for transferring the toner images transferred to the intermediate transfer belt 11 to the paper P. The plurality of primary transfer rollers 12 are in contact with the photosensitive bodies 2 via the intermediate transfer belt 11, respectively.

[0072] Thus, the intermediate transfer belt 11 and each photosensitive body 2 come into contact with each other, and a primary transfer nip is formed therebetween. On the other hand, the secondary transfer roller 13 comes into contact with one of the rollers that stretch the intermediate transfer belt 11 via the intermediate transfer belt 11. Thus, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

[0073] In the image forming apparatus 100, a paper conveying path 14 is formed to convey the paper P fed from the paper feed device 7. A pair of timing rollers 15 are provided in the paper conveying path 14 from the paper feed device 7 to the secondary transfer nip (secondary transfer roller 13).

[0074] Next, refer to Figure 1 The printing operation of the above-mentioned image forming apparatus will be described.

[0075] When the printing operation is started, the photosensitive body 2 is moved along the axis of each image forming unit 1Y, 1M, 1C, 1Bk. Figure 1 The photosensitive body 2 is driven to rotate in the clockwise direction, and the surface of the photosensitive body 2 is charged to a uniform high potential by the charging device 3. Then, according to the image information of the original document read by the original document reading device or the print information instructed to be printed by the terminal, the surface of the photosensitive body 2 is exposed by the exposure device 6, so that the potential of the exposed part is reduced to form an electrostatic latent image. Then, the toner is supplied to the electrostatic latent image from the developing device 4, and a toner image is formed on each photosensitive body 2.

[0076] When the toner image formed on each photoreceptor 2 reaches the primary transfer nip portion (the position of the primary transfer roller 12) as each photoreceptor 2 rotates, Figure 1 The toner image transferred to the intermediate transfer belt 11 is transferred in an overlapping manner in sequence by the intermediate transfer belt 11 that is rotated and driven in the counterclockwise direction. Then, the toner image transferred to the intermediate transfer belt 11 is transported to the secondary transfer nip (the position of the secondary transfer roller 13) as the intermediate transfer belt 11 rotates, and is transferred to the transported paper P at the secondary transfer nip.

[0077] The paper P is supplied from the paper supply device 7. The paper P supplied from the paper supply device 7 is temporarily stopped by the timing roller 15, and then conveyed to the secondary transfer nip portion at the timing when the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip portion. In this way, a full-color toner image is carried on the paper P. In addition, after the toner image is transferred, the toner remaining on each photosensitive body 2 is removed by each cleaning device 5.

[0078] The paper P with the toner image transferred thereto is conveyed to the fixing device 9, and the toner image is fixed on the paper P by the fixing device 9. Then, the paper P is discharged to the outside of the apparatus by the paper discharge device 10, and a series of printing operations are completed.

[0079] (●Fixing device)

[0080] Next, an embodiment of a fixing device as a nip forming unit will be described. Figure 2 As shown, the fixing device 9 involved in this embodiment includes a fixing belt 20 composed of an endless belt, a pressure roller 21 as an opposing member that contacts the outer peripheral surface of the fixing belt 20 to form a fixing clamping portion N, a heater 22 as a heating member that heats the fixing belt 20, a heater holder 23 as a holding member that holds the heater 22, a support member 24 as a supporting member that supports the heater holder 23, a thermistor 25 as a temperature detection mechanism that detects the temperature of the heater 22, etc.

[0081] The fixing belt 20 has a cylindrical base made of polyimide (PI) with an outer diameter of 25 mm and a thickness of 40 to 120 μm. To improve durability and ensure mold release properties, a mold release layer with a thickness of 5 to 50 μm is formed on the outermost layer of the fixing belt 20 and is made of a fluorine resin such as PFA or PTFE.

[0082] An elastic layer made of rubber or the like with a thickness of 50 to 500 μm may be provided between the base and the release layer. In addition, the base of the fixing belt 20 is not limited to polyimide, and may be a heat-resistant resin such as PEEK or a metal base such as nickel (Ni) or SUS. The inner peripheral surface of the fixing belt 20 may be coated with polyimide or PTFE as a sliding layer.

[0083] The pressure roller 21 is composed of a solid iron core rod 21a with an outer diameter of, for example, 25 mm, an elastic layer 21b formed on the surface of the core rod 21a, and a release layer 21c formed on the outside of the elastic layer 21b. The elastic layer 21b is formed of silicone rubber and has a thickness of, for example, 3.5 mm. In order to improve the demolding property, it is preferred that the surface of the elastic layer 21b is formed with a release layer 21c composed of a fluorine resin layer with a thickness of, for example, about 40 μm.

[0084] The pressure roller 21 applies force to the fixing belt 20 side by the force applying mechanism, so that the pressure roller 21 is pressed against the heater 22 via the fixing belt 20. Thus, a fixing nip N is formed between the fixing belt 20 and the pressure roller 21. In addition, the pressure roller 21 is configured to be rotationally driven by the driving mechanism. Figure 2 When the fixing belt 20 rotates in the direction of the arrow, the fixing belt 20 is driven to rotate accordingly.

[0085] The heater 22 is a planar heating component provided in a strip shape in the width direction of the fixing belt 20, and is composed of a plate-shaped base material 30, a resistance heating element 31 provided on the base material 30, and an insulating layer 32 covering the resistance heating element 31. In addition, the heater 22 is in contact with the inner peripheral surface of the fixing belt 20 on the insulating layer 32 side, and the heat generated from the resistance heating element 31 is transferred to the fixing belt 20 via the insulating layer 32.

[0086] In the present embodiment, the impedance heating element 31 and the insulating layer 32 are arranged on the fixing belt 20 side (fixing nip N side) of the base material 30, but conversely, the impedance heating element 31 and the insulating layer 32 may be arranged on the heater holder 23 side of the base material 30. In this case, since the heat of the impedance heating element 31 is transferred to the fixing belt 20 via the base material 30, the base material 30 is preferably composed of a material with high thermal conductivity such as aluminum nitride. In addition, by forming the base material 30 with a material with good thermal conductivity, even if the impedance heating element 31 is arranged on the side of the base material 30 opposite to the fixing belt 20 side, the fixing belt 20 can be sufficiently heated.

[0087] The heater support 23 and the support 24 are arranged on the inner peripheral side of the fixing belt 20. The support 24 is made of a metal channel material, and its two end portions are supported by the two side plates of the fixing device 9. The support 24 supports the heater holder 23 and the heater 22 held thereby, and when the pressure roller 21 is pressed by the fixing belt 20, the heater 22 reliably receives the pressing force of the pressure roller 21, thereby stably forming the fixing nip N.

[0088] The heater support 23 is preferably formed of a heat-resistant material because it is easily heated by the heat of the heater 22. For example, when the heater support 23 is formed of a heat-resistant resin with low thermal conductivity such as LCP, heat transfer from the heater 22 to the heater support 23 can be suppressed, and the fixing belt 20 can be effectively heated.

[0089] In addition, in order to reduce the contact area between the heater holder 23 and the heater 22 and reduce the amount of heat transferred from the heater 22 to the heater holder 23, the heater holder 23 is in contact with the base material 30 of the heater 22 via the protrusion 23a. Furthermore, as in the present embodiment, by making the protrusion 23a of the heater holder 23 contact the base material 30 other than the back side of the portion where the impedance heating element 31 is arranged, that is, avoiding the portion where the temperature of the base material 30 is likely to increase, the amount of heat transferred to the heater holder 23 can be further reduced, and the fixing belt 20 can be effectively heated.

[0090] In addition, guide portions 26 for guiding the fixing belt 20 are provided in the heater holder 23. The guide portions 26 are provided on the upstream side ( Figure 2 The lower side of the heater 22 in the Figure 2 The upper side of the heater 22 in FIG.

[0091] In addition, if Figure 3 As shown in FIG. 1 , a plurality of guide portions 26 on the upstream side and the downstream side are arranged at intervals in the longitudinal direction (the belt width direction) of the heater 22. Each guide portion 26 is formed in a substantially fan-shaped shape and has an arc-shaped or convexly curved belt facing surface 260 extending in the belt circumferential direction so as to face the inner circumferential surface of the fixing belt 20 (see FIG. 1 ). Figure 2 ). In addition, Figure 3 As shown, in this embodiment, except that the width W of the guide portions 26 arranged at the two ends in the long side direction of the heater 22 is formed to be larger than that of other guide portions 26, the width W, the length (circumference) L in the circumferential direction of the belt, and the height E of each guide portion 26 are all formed to be the same.

[0092] In the fixing device 9 according to the present embodiment, when the printing operation starts, the pressure roller 21 is driven to rotate, and the fixing belt 20 starts to rotate therewith. At this time, the fixing belt 20 is guided by the inner peripheral surface of the fixing belt 20 contacting the facing surface 260 of the guide portion 26, so that the fixing belt 20 rotates stably and smoothly.

[0093] In addition, by supplying power to the resistance heating element 31 of the heater 22, the fixing belt 20 is heated. Then, when the temperature of the fixing belt 20 reaches a predetermined target temperature (fixing temperature), as shown in FIG. Figure 2 As shown, when the paper P carrying the unfixed toner image is conveyed between the fixing belt 20 and the pressure roller 21 (fixing nip N), the unfixed toner image is heated and pressurized, and is fixed on the paper P.

[0094] (● Heater structure)

[0095] Figure 4 FIG. 2 is a top view of the heater according to the present embodiment. Figure 4 As shown, the heater 22 involved in this embodiment has a plurality of impedance heating elements 31 arranged at intervals in the long side direction (band width direction). In other words, a heating portion 35 divided into a plurality of parts in the band width direction is formed by the plurality of impedance heating elements 31. The heating portion 35 can be divided into at least three or four or more end heaters for heating the two end portions and a central heater for heating the central portion.

[0096] Each resistance heating element 31 is electrically connected in parallel to a pair of electrode portions 34 provided at both ends in the longitudinal direction of the base material 30 via a power supply line 33. The power supply line 33 is formed of a conductor having a lower resistance value than the resistance heating element 31.

[0097] From the viewpoint of ensuring the insulation between the impedance heating elements 31, the gap between adjacent impedance heating elements 31 is preferably 0.2 mm or more, and more preferably 0.4 mm or more. In addition, if the gap between adjacent impedance heating elements 31 is too large, the temperature is likely to drop in the gap portion, so from the viewpoint of suppressing the temperature unevenness in the entire long side direction, it is preferably 5 mm or less, and more preferably 1 mm or less.

[0098] The resistance heating element 31 is made of a material having a PTC (positive temperature coefficient) characteristic, and has a characteristic that the resistance value increases (heater output decreases) when the temperature rises. According to this characteristic, for example, when a paper having a width smaller than the overall width of the heating portion 35 is passed through the paper, the heat of the fixing belt 20 is not taken away by the paper in the area outside the paper width, so the temperature of the resistance heating element 31 corresponding to this portion rises.

[0099] Since the voltage applied to the impedance heating element 31 is constant, if the temperature of the impedance heating element 31 outside the paper width rises and its resistance value rises, the output (heat generation) will be relatively reduced, and the temperature rise of the end portion is suppressed. In addition, by electrically connecting multiple impedance heating elements 31 in parallel, the temperature rise of the non-paper portion can be suppressed while maintaining the printing speed.

[0100] The heating element constituting the heating portion 35 may be a heating element other than a resistance heating element having a PTC characteristic. The heating elements may be arranged in a plurality of rows in the short-side direction of the heater 22 .

[0101] The impedance heating element 31 can be formed by applying a paste mixed with silver palladium (AgPd) or glass powder to the base material 30 by screen printing, and then sintering the base material 30. In this embodiment, the resistance value of the impedance heating element 31 is 80Ω at room temperature.

[0102] In addition to the above, the material of the resistance heating element 31 may also be a silver alloy (AgPt) or a ruthenium oxide (RuO2) resistance material. The material of the power supply line 33 and the electrode part 34 may be formed of silver (Ag) or silver palladium (AgPd) by screen printing or the like.

[0103] As the material of the substrate 30, ceramics such as alumina and aluminum nitride, glass, mica and other non-metallic materials with excellent heat resistance and insulation are preferred. In this embodiment, an alumina substrate with a short side width of 8 mm, a long side width of 270 mm and a thickness of 1.0 mm is used.

[0104] In addition, an insulating material may be stacked on a conductive material such as a metal to form the base material 30. As the metal material, aluminum or stainless steel is preferred at low cost. In addition, in order to improve the thermal uniformity of the heater 22 and improve the image quality, the base material 30 may also be composed of a material with high thermal conductivity such as copper, graphite, and graphene.

[0105] The insulating layer 32 is made of, for example, heat-resistant glass having a thickness of 75 μm. The insulating layer 32 covers the resistance heating element 31 and the power supply line 33 , insulates and protects them, and maintains sliding properties with the fixing belt 20 .

[0106] Figure 5 FIG. 1 is a schematic diagram of a circuit for supplying electric power to a heater according to the present embodiment.

[0107] like Figure 5As shown, in this embodiment, the power supply circuit for supplying power to each resistance heating element 31 is formed by electrically connecting the AC power source 200 to the electrode portion 34 of the heater 22. In addition, a bidirectional thyristor 210 for controlling the amount of power supplied is provided in the power supply circuit.

[0108] The control unit 220 controls the amount of power supplied to each resistance heating element 31 via the bidirectional thyristor 210 based on the detected temperature of the thermistor 25 as a temperature detection means. The control unit 220 is composed of a microcomputer including a CPU, ROM, RAM, an I / O interface, and the like.

[0109] In this embodiment, the thermistor 25 as a temperature detection mechanism is respectively arranged in the central area in the long side direction of the heater 22 which is within the minimum paper width and on the side of one end in the long side direction of the heater 22. Furthermore, a thermostat 27 is arranged on the side of one end in the long side direction of the heater 22, and when the temperature of the impedance heating element 31 becomes higher than a predetermined temperature, it serves as a power cutoff mechanism for cutting off the power supply to the impedance heating element 31. The thermistor 25 and the thermostat 27 are in contact with the back side of the base material 30 (the opposite side to the side where the impedance heating element 31 is arranged) to detect the temperature of the impedance heating element 31.

[0110] Next, refer to Figure 6 The control operation of the heater involved in this embodiment will be described with reference to the flowchart of FIG. 1. First, when the printing operation is started in the image forming device ( Figure 6 The control unit 220 starts supplying power from the AC power source 200 to each impedance heating element 31 of the heater 22 ( Figure 6 of S2).

[0111] As a result, each resistance heating element 31 starts to generate heat, and the fixing belt 20 is heated. At this time, the temperature T4 (T2) of the resistance heating element 31 located in the central area of ​​the heater 22 is detected by the thermistor (central thermistor) 25 disposed in the central area in the longitudinal direction of the heater 22. Figure 6 Then, the control unit 220 controls the amount of power supplied to each impedance heating element 31 through the bidirectional thyristor 210 based on the temperature T4 obtained from the central thermistor 25, so that each impedance heating element 31 reaches a predetermined temperature ( Figure 6 S4).

[0112] In addition, the temperature T8 (T2) of the resistance heating element 31 is detected by the thermistor (end thermistor) 25 disposed at the end side of the heater 22 in the longitudinal direction. Figure 6 Then, it is determined whether the temperature T8 detected by the end thermistor 25 is above the predetermined temperature TN (T8 ≥ TN) ( Figure 6If the temperature is lower than the predetermined temperature TN, abnormal low temperature occurs (breakage occurs) and the power supply to the heater 22 is cut off ( Figure 6 S7 of the image forming apparatus), and an error indication is displayed on the operation panel of the image forming apparatus ( Figure 6 On the other hand, if the detected temperature T8 is above the predetermined temperature TN, the printing operation is started as if abnormal low temperature has not occurred ( Figure 6 S9).

[0113] In addition, if the temperature control based on the detection of the central thermistor 25 cannot be performed due to damage or disconnection of the impedance heating element 31, the other impedance heating elements 31 including the impedance heating element 31 at the end of the long side direction may become abnormally high temperature. In this case, when the impedance heating element 31 reaches a predetermined temperature or above, the thermostat 27 is activated to cut off the power supply to the impedance heating element 31 to prevent the impedance heating element 31 from becoming abnormally high temperature.

[0114] (●Paper separation mechanism)

[0115] Fig. 7A The figure is a conceptual diagram of a fixing device having a paper separation mechanism 300 for separating a paper passing through a fixing nip portion from a fixing belt 20. The paper separation mechanism 300 has a separation plate 310 as a paper separation member, and the paper is separated from the fixing belt 20 by the separation plate 310. As described later, the separation plate 310 is arranged to be movable in a direction approaching the fixing belt 20 and a direction away from the fixing belt 20.

[0116] The heater 22 and the heater holder 23 as the nip forming members are arranged between the approach position where the fixing nip is pressed by the pressure roller 21 and the separated position where the fixing nip is released. Fig. 7A Then, in a state where the separation plate 310 is restricted in rotation by a first restriction portion of a rotation restriction hole 321 described later, the heater 22 and the heater holder 23 can move to the above-mentioned separated position.

[0117] The separation plate 310 extends parallel to the axial direction of the fixing belt 20, and has contact portions 313 at both ends in the longitudinal direction thereof for contacting the outer peripheral surface of the fixing belt 20. The contact portions 313 contact the outer peripheral surfaces at both ends in the axial direction of the fixing belt 20, so that the interval between the separation plate 310 and the fixing belt 20 is limited to a predetermined size.

[0118] The fixing belt 20 is supported slidably at both ends in the axial direction by flanges 400 as guide members. The flanges 400 are annular and slidably inserted into the inner circumference of both ends in the axial direction of the fixing belt 20. Thus, the fixing belt 20 is guided to rotate by the flanges 400.

[0119] like Figure 7Ba As shown, a gap (play) C is generally formed between the inner peripheral surface of both ends of the fixing belt 20 in the axial direction and the outer peripheral surface of the flange 400. Due to the existence of the play C, the fixing belt 20 can smoothly move around.

[0120] However, when the fixing belt 20 and the pressure roller 21 are out of parallelism, the fixing belt 20 may be inclined toward the flange 400 along the pressure roller 21. This may cause the fixing belt 20 to be unstable in its circulation and may be a major cause of paper jams.

[0121] In an embodiment of the present invention, Figure 7Ba → Figure 7Bb As shown, by contacting at least one of the contact portions 313 at both ends of the separation plate 310 in the longitudinal direction with the outer peripheral surface of at least one end of the fixing belt 20, the inclination (parallelism deviation) of the fixing belt 20 is suppressed, and the circulation mobility of the fixing belt 20 is stabilized. The position of the contact portion 313 is as shown in FIG. Figure 7Ba , Figure 7Bb As shown, it may be at a position facing the flange 400 in the radial direction of the fixing belt 20. In this way, the looseness of the fixing belt 20 can be minimized.

[0122] In detail, Figure 7Ba In the embodiment, the separation plate 310 is located relatively far away from the fixing belt 20 or the flange 400. Therefore, the contact portion 313 on one side (left side) of the separation plate 310 abuts against the outer peripheral surface of the end of the fixing belt 20, while the contact portion 313 on the opposite side is away from the outer peripheral surface of the end of the fixing belt 20.

[0123] Therefore, a relatively large gap is generated between the front end portion 311 of the separation plate 310 which is a non-contact portion not in contact with the fixing belt 20 and the outer peripheral surface of the fixing belt 20. When such a large gap exists, paper passes through the gap and is wound around the fixing belt 20, which easily causes a paper jam.

[0124] Therefore, within the range where the front end portion 311 of the separation plate 310 does not contact the fixing belt 20, as shown in FIG. Figure 7Bb As shown, the separation plate 310 is brought close to the fixing belt 20. As a result, the contact portions 313 at both ends of the separation plate 310 come close to the left and right flanges 400 while being in contact with the outer peripheral surfaces at both ends of the fixing belt 20.

[0125] exist Figure 7Ba In the embodiment, due to the clearance C between the flange 400 and the fixing belt 20, the inclination (parallelism deviation) of the fixing belt 20 relative to the axis of the flange 400 becomes larger, and the circumferential mobility of the fixing belt 20 becomes unstable. Figure 7BbAs shown, if the contact portions 313 at both ends of the separation plate 310 are brought close to the left and right flanges 400 , the inclination (parallelism deviation) of the fixing belt 20 can be suppressed, and the circulating mobility of the fixing belt 20 can be stabilized.

[0126] exist Figure 7Bb In the state of being in a ...

[0127] Next, refer to Figure 7Bc to Figure 7Be The deformation (elastic deformation) of the separation plate 310 is described below. The separation plate 310 is made of a heat-resistant metal such as stainless steel, but is easily deformed due to its thin thickness. Figure 7Ba → Figure 7Bb As shown, when the separation plate 310 is brought close to the fixing belt 20, the T portion ( Figure 7Bc The T portion) may be pulled by the rotation of the fixing belt 20 and change its position toward the downstream side (the back side of the paper) in the rotation direction.

[0128] In addition, even if Figure 7Bb As shown, the separation plate 310 is not brought close to the fixing belt 20, because Figure 7Ba The left and right clearances C of the fixing belt 20 shown in the figure increase or decrease (regularly or irregularly). As described above, the contact portion 313 on either side may be pulled by the rotation of the fixing belt 20 to the downstream side in the rotation direction ( Figure 7Bc Thus, the separation plate 310 changes as shown in FIG. Figure 7Bc , Figure 7Bd As shown in the T portion, it is twisted in the long side direction or buckled (elastic buckling) in the short side direction.

[0129] However, even if the separation plate 310 is deformed (elastically deformed) in this way, the left and right contact portions 313 of the separation plate 310 are Figure 7Be As shown in the figure, the front end portion 311 of the separation plate 310 is in contact with the fixing belt 20, and the "small gap" between the outer peripheral surface of the fixing belt 20 can be stably maintained. Even if the size of the left and right clearance C of the fixing belt 20 changes, the size of the "small gap" is always constant in the axial direction of the fixing belt 20, so paper jams can be effectively prevented.

[0130] Figure 7Be The T section corresponds to Figure 7Bc and Figure 7BdIn the T portion, in the example shown in the figure, the clearance C (small) between the flange 400 and the fixing belt 20 is the same as the clearance C (small) on the opposite side, but the contact portion 313 of the separation plate 310 pushes the end of the fixing belt 20, so that the clearance C on the upper side becomes smaller and the clearance C on the opposite side becomes larger. As a result, the inclination of the fixing belt 20 becomes smaller, and the effect of preventing the end of the belt from being damaged due to the belt deviation in the axial direction can be obtained.

[0131] It is known that in order to improve the separation of the paper from the fixing belt 20, it is effective to increase the curvature of the fixing belt 20 on the outlet side of the fixing nip portion. Figure 7C As shown in the figure, the nip forming member NF holding the heater is made shorter than the axial length of the fixing belt 20, and the flange 400 is moved in the direction away from the fixing nip portion as shown by the arrow to pull the fixing belt 20. As a result, the curvature of the fixing belt 20 at the outlet and inlet sides of the fixing nip portion is increased over the entire length of the fixing belt 20 in the axial direction, and the separation performance of the paper becomes good.

[0132] On the other hand, Fig.7D As shown in FIG. 1 , when the nip forming member SH including the planar heater is longer than the axial length of the fixing belt 20 and is exposed from both ends of the fixing belt 20 in the axial direction, if the flange 400 is pulled in a direction away from the fixing nip, excessive tension may be applied to the fixing belt 20. If excessive tension is applied to the fixing belt 20, the inner surface of the fixing belt 20 may be worn, or the sliding load may increase, causing the fixing belt 20 to slip, thereby causing paper conveyance failure.

[0133] In addition, if excessive tension is applied to the fixing belt 20, the fixing unit assembly performance may also be problematic. Therefore, the flange 400 and the clamp forming member SH are set to have a small radial size so that the inner surface of the fixing belt 20 has a play. As a result, there is a limit to increasing the curvature of the fixing belt 20 on the outlet side of the fixing clamp, and there is a problem in improving the paper separation performance. According to the embodiment of the present invention, such a problem can also be solved.

[0134] Fig. 8A FIG. 3 is a specific embodiment of the paper separation mechanism 300 and the separation plate 310. In this embodiment, the separation plate 310 is configured to be rotatable around the support shaft 322. Fig. 8A As shown, the separation plate 310 is provided so that the front end portion 311 of the separation plate 310 can rotate in a direction approaching or moving away from the fixing belt 20 .

[0135] Support shaft 322 Figure 8CAs shown (only one side is shown), the support shaft 322 is protruded on the inner surfaces of the pair of side plates 320 facing each other. The support shaft 322 is rotatably fitted into the shaft holes 315 formed at both ends of the separation plate 310.

[0136] The side plate 320 has a U-shaped cutout 324 for rotatably supporting the two end shafts of the pressure roller 21. A rotation limiting hole 321 is formed above the cutout 324 of the side plate 320, which is a fan-shaped movement limiting hole centered on the support shaft 322. The rotation range (movement position) of the separation plate 310 is limited by the rotation limiting hole 321.

[0137] like Figure 8C As shown, the separation plate 310 has rotation limiting pieces 312 protruding in the long side direction as movable limiting pieces at both ends thereof, and the rotation limiting pieces 312 are inserted into the rotation limiting holes 321. The movement limiting mechanism or the rotation limiting mechanism of the separation plate 310 is formed by these rotation limiting pieces 312 and the rotation limiting holes 321.

[0138] That is, one end portion ( Figure 8C The left end portion of the rotation restriction hole 321 (left end portion in the figure) constitutes a first restriction portion to determine the moving position or rotation position of the separation plate 310 in the direction in which the front end portion 311 of the separation plate 310 approaches the fixing belt 20. In addition, the other end portion ( Figure 8C The right end portion in the figure (a) constitutes a second limiting portion to determine the moving position or rotational position of the separation plate 310 in the direction in which the front end portion 311 of the separation plate 310 moves away from the fixing belt 20.

[0139] In addition, since an appropriate gap is provided between the surface (arc-shaped surface) other than the first limiting portion and the second limiting portion of the rotation limiting hole 321 and the rotation limiting plate 312 , the arc-shaped surface will not interfere with the rotation limiting plate 312 and hinder the rotation of the separation plate 310 .

[0140] When the front end portion 311 of the separation plate 310 rotates in a direction close to the fixing belt 20, the preferred interval between the front end portion 311 and the fixing belt 20 is 0.6 to 1.2 mm or 0.6 to 1.3 mm. If the interval between the fixing belt 20 and the separation plate 310 is too small, the separation plate 310 and the fixing belt 20 may come into contact and damage the belt, which may cause abnormal images. If the interval of 0.6 mm is provided, damage to the fixing belt 20 can be prevented.

[0141] If the gap between the fixing belt 20 and the separation plate 310 is too large, the paper passes through the large gap and is wound around the fixing belt 20, which easily causes a paper jam. If the gap is 1.2 mm or less than 1.3 mm, it is possible to prevent the paper from being wound around the fixing belt 20 and causing a paper jam. In addition, the relationship between the rotation limiting piece 312 and the rotation limiting hole 321 may be reversed, and the rotation limiting hole may be provided on the separation plate 310 side, and the rotation limiting piece may be provided on the side plate 320 side.

[0142] L-shaped contact portions 313 are formed at the lower ends of the longitudinal ends of the separation plate 310. The contact portions 313 are disposed at positions facing the flange 400 in the radial direction of the fixing belt 20 to suppress looseness of the fixing belt 20.

[0143] A tension spring 330 is provided between the spring engaging portions 314 at both ends of the separation plate 310 and the spring engaging portions 323 at the upper ends of the side plates. The separation plate 310 is extended in a direction of rotation around the support shaft 322 by the tension spring 330. Figure 8B , Figure 8C The force is applied in the clockwise direction.

[0144] The rotational urging direction is the direction in which the front end portion 311 of the separation plate 310 approaches the fixing belt 20. Since the separation plate 310 is easily deformed as described above, in order to rotationally urge the separation plate 310 reliably, it is preferable to attach tension springs 330 to both ends thereof.

[0145] If there is no contact portion 313, the force of the tension spring 330 is applied, such as Fig. 9A As shown in FIG. 1 , the front end portion 311 of the separation plate 310 can be brought into contact with the outer peripheral surface of the fixing belt 20. In this state, a portion 321a is provided at one end portion (left end portion) of the rotation limiting hole 321 at a position where the rotation limiting piece 312 contacts. Therefore, even if the contact portion 313 becomes inoperative for some reason, the separation plate 310 cannot be moved. Fig. 9A The state further rotates clockwise.

[0146] (● Dealing with paper jams)

[0147] like Fig. 9B As shown in FIG. 1 , when a paper jam occurs and the paper P is wound around the fixing belt 20 , the separation plate 310 rotates counterclockwise to avoid the paper P, thereby avoiding collision with the paper P. Thus, damage to the paper P can be prevented. Fig. 9C As shown, when the paper P wound around the fixing belt 20 is pulled out downward from the fixing nip, the separation plate 310 rotates counterclockwise to avoid the paper P, so that the paper P can be pulled out without being damaged.

[0148] Even if the separation performance of the paper is improved by the function of the separation plate 310, if the image with toner carried on the front end of the paper P is fixed due to a printing setting error, the paper P may sometimes slip between the separation plate 310 and the fixing belt 20, and the paper P may be wound around the fixing belt 20. If the paper P is wound around the fixing belt 20 in multiple layers or if large wrinkles are formed on the paper P, the separation plate 310 may be strongly contacted when the paper P is pulled out, which may cause the separation plate 310 to be deformed or damage the fixing belt 20.

[0149] Therefore, the present embodiment adopts a configuration in which the separation plate 310 is pressed by the tension spring 330. According to this configuration, the separation plate 310 is opened against the tension spring 330 when the paper P is pulled out, so that deformation or damage of the separation plate 310 can be suppressed. In addition, since the force when pulling out the paper P can be reduced, the operability is improved.

[0150] In order to reduce the force when pulling out, it is effective to make the opening amount of the separation plate 310, that is, the gap between the rotation limiting piece 312 of the separation plate 310 and the rotation limiting hole 321 of the side plate 320 larger than the decompression amount when the fixing nip is decompressed. The decompression amount when the fixing nip is decompressed can be in the pressurized state and the decompressed state, such as Fig.10 As shown in FIG. 1 , the distance GAP between the core bar 21 a of the pressure roller 21 and the nip forming member SH is measured with a vernier caliper or the like and subtracted from the measured distance GAP.

[0151] However, if the opening amount of the rotation limiting hole 321 is too large, the front end portion 311 of the separation plate 310 may contact the pressure roller 21, or the pressure roller 21 may be damaged by the contact. Therefore, it is preferable to set the size of the rotation limiting hole 321 in such a way that the separation plate 310 stops rotating at a position before the front end portion 311 of the separation plate 310 contacts the pressure roller 21. That is, when the separation plate 310 rotates in a direction to increase the gap between its front end portion 311 and the fixing belt 20, before contacting the pressure roller 21, the other end portion ( Figure 8C The right end in the middle) is used to limit the rotation.

[0152] As another method of preventing contact with the pressure roller 21, the position of the support shaft 322 of the separation plate 310 may be designed so as not to contact the pressure roller 21. To this end, the diameter of the pressure roller 21 is made smaller than the diameter of the fixing belt 20, or the center of the pressure roller 21 is made farther away from the separation plate 310 than the center of the fixing belt 20 ( Fig.9D The lower) offset in the figure is also valid.

[0153] (●Composition of pressurization and depressurization of the fixing nip)

[0154] As the pressurizing structure of the fixing nip portion, there may be two pressurizing structures, the first and the second. The first pressurizing structure is a structure in which the fixing belt 20 side (heater holder 23) is fixed, the pressurizing roller 21 is allowed to contact and separate with respect to the fixing belt 20, and a force is applied to the fixing belt 20 side. The second pressurizing structure is a structure in which the pressurizing roller 21 side (core rod of the pressurizing roller 21) is fixed, the pressurizing roller 21 side is allowed to contact and separate with respect to the pressurizing roller 21, and a force is applied to the pressurizing roller 21 side.

[0155] The latter second pressure structure is preferred because it can further reduce the force of pulling out the paper P when dealing with a paper jam. That is, in the case of the second pressure structure, when the pressure is released, the fixing belt 20 and the pressure roller 21 are separated, and the fixing belt 20 and the separation plate 310 are also separated. Therefore, the position change of the tension spring 330 becomes smaller, and the force of pulling out the paper P can be further reduced.

[0156] In addition, by making the clearance of the rotation limiting hole 321 in the force application direction smaller than the decompression amount, the separation plate 310 is Fig. 9B The clockwise rotation of the fixing belt 20 is limited to a predetermined value, and as a result, the gap between the fixing belt 20 and the front end portion 311 of the separation plate 310 is widened, so that the paper P is more easily pulled out.

[0157] In addition, when a paper jam occurs, if the paper cannot be fully seen from the fixing nip, it is difficult for the user to pull out the paper P. If the interval between the fixing belt 20 and the front end portion 311 of the separation plate 310 can be increased, the pressure roller 21 and the fixing belt 20 can be easily rotated in the opposite direction, and the paper P can be pulled toward the upstream side of the fixing nip ( Fig. 9B Middle and lower part) to pull out with sufficient length.

[0158] On the other hand, the trajectory of the fixing belt 20 changes during forward and reverse rotations of the fixing belt 20 during jam processing. Therefore, the second pressurizing structure is preferred in which the fixing belt 20 and the front end 311 of the separation plate 310 do not contact each other even if the trajectory of the fixing belt 20 changes.

[0159] (●Inner week usage rate)

[0160] The inner peripheral utilization rate of the fixing belt 20 (see Japanese Patent Application Laid-Open No. 2019-082733) is preferably 95 to 99.8%. Fig.11A When the fixing belt 20 is cut out as shown in the oblique line portion and wound around the flange 400 Fig. 11B The overlap amount W is calculated by the following formula.

[0161] Inner circumference usage rate = [(circumference L of fixing belt 20 - overlap amount W) / circumference L of fixing belt 20] × 100% Circumference L of fixing belt 20 Fig. 11CThe figure shows the full length of the cut oblique line portion.

[0162] The above inner circumference utilization ratio only indicates the ratio of the circumference length of the guide portion to the circumference L of the fixing belt 20. Although it is an indicator of assembly (fitting), it still has room for improvement as an indicator of belt bias or paper separation. That is, even if the inner circumference utilization ratio is the same, Fig. 12A , Fig. 12B As shown, the slack in the width direction of the fixing nip varies depending on the rigidity of the fixing belt 20, the width of the fixing nip, and the shape of the flange 400. Specifically, the higher the rigidity of the fixing belt 20, the narrower the width of the fixing nip, and the further the guide shape of the flange 400 is from a perfect circle, the smaller the slack.

[0163] Therefore, the relaxation rate can be specified by directly measuring the relaxation on the downstream side of the fixing nip with a height gauge. Fig.13 The method for measuring the relaxation rate will be described.

[0164] Place the fixing unit Fig.13 The direction of the fixing nip is fixed, and the pressure roller 21 is rotated for more than one revolution and then stopped while the pressure roller 21 is pressurizing the fixing nip. Fig.13 As shown in (a) of FIG. 1 , the height coordinates of the top of the fixing belt 20 in the region where the flange 400 is located in the axial direction of the fixing belt 20 at this time are measured using a height meter.

[0165] Then, if Fig.13 As shown in (b), the height coordinates when the position where the vertex coordinates were measured was pressed against the flange were measured. The height dimension difference before and after pressing was taken as the relaxation amount, and the relaxation rate was calculated by the following formula.

[0166] Relaxation rate = [relaxation amount / belt diameter] × 100%

[0167] If the relaxation rate is too small, assembly becomes difficult, and there is a problem that the fixing belt 20 is worn due to the sliding friction between the flange 400 and the fixing belt 20. If the relaxation rate is too large, the fixing belt 20 is easy to tilt, and the curvature of the fixing nip outlet becomes small, the separation property becomes poor, and it becomes difficult to arrange the separation plate 310. Therefore, the relaxation rate is preferably 0.1 to 10%, and more preferably 0.5 to 5%.

[0168] (●Configuration of high thermal conductivity components)

[0169] Next, refer to Figure 14 to Figure 32 An embodiment in which a high thermal conductivity component is arranged on the heater holder 23 is described. Fig.14As shown, the fixing device 9 involved in this embodiment includes a fixing belt 20 as a rotating member or a fixing member, a pressure roller 21 as an opposing rotating member or a pressure member, a heater 22 as a heating member, a heater holder 23 as a holding member, a support member 24 as a supporting member, a thermistor 25 as a temperature detection member, a first high thermal conductivity member 28, etc.

[0170] The fixing belt 20 is an endless belt. The pressure roller 21 is in contact with the outer peripheral surface of the fixing belt 20 and forms a fixing nip N with the fixing belt 20. The heater 22 heats the fixing belt 20. The heater holder 23 holds the heater 22. The support member 24 supports the heater holder 23.

[0171] The thermistor 25 detects the temperature of the first high thermal conductive member 28. Fig.14 The direction perpendicular to the paper surface is the long side direction of the fixing belt 20, the pressure roller 21, the heater 22, the heater holder 23, the support member 24, the first high thermal conductive member 28, etc., and this direction is simply referred to as the long side direction below. In addition, the long side direction is the width direction of the paper being transported, the belt width direction of the fixing belt 20, and the axial direction of the pressure roller 21.

[0172] In the present embodiment, the first highly thermally conductive member 28 is provided to suppress the temperature drop in the interval and suppress the temperature variation in the arrangement direction of the fixing belt 20. The first highly thermally conductive member 28 will be described in more detail below.

[0173] like Fig.14 As shown, the first high thermal conductivity component 28 is Fig.14 The first highly thermally conductive member 28 is disposed between the heater 22 and the support member 24 in the left-right direction, and is particularly sandwiched between the heater 22 and the heater holder 23. That is, one surface of the first highly thermally conductive member 28 abuts against the back surface of the heater 22, and the other surface abuts against the heater holder 23.

[0174] The support member 24 supports the heater holder 23, the first high thermal conductive member 28, and the heater 22 by making the contact surfaces 24a1 of the two vertical portions 24a extending in the thickness direction of the heater 22 etc. contact with the heater holder 23. Fig.14 In the vertical direction of the fixing belt 20, the contact surface 24a1 is provided outside the range where the resistance heating element 31 is provided. Thus, the heat transfer from the heater 22 to the support member 24 can be suppressed, and the heater 22 can heat the fixing belt 20 efficiently.

[0175] like Fig.15As shown, the first high thermal conductive component 28 is composed of a plate having a thickness of 0.3 mm, a length of 222 mm in the arrangement direction, and a width of 10 mm in the arrangement cross direction. In this embodiment, the first high thermal conductive component 28 is composed of a single plate, but it can also be composed of multiple components. Fig.15 Omitted Fig.14 The guide component 26 is described.

[0176] The first highly thermally conductive member 28 is inserted into the recess 23b of the heater holder 23, and when the heater 22 is mounted from above, it is sandwiched and held by the heater holder 23 and the heater 22. In the present embodiment, the width of the first highly thermally conductive member 28 in the arrangement direction is set to be substantially the same as the width of the heater 22 in the arrangement direction.

[0177] The first highly thermally conductive member 28 and the heater 22 are restricted from moving in the arrangement direction by forming two side walls (arrangement direction restriction portions) 23b1 of the recess 23b in the arrangement direction. Thus, by restricting the positional deviation of the first highly thermally conductive member 28 in the arrangement direction within the fixing device 9, the heat conduction efficiency can be improved relative to the target range in the arrangement direction. In addition, the first highly thermally conductive member 28 and the heater 22 are restricted from moving in the arrangement-crossing direction by forming two side walls (arrangement-crossing direction restriction portions) 23b2 of the recess 23b in the arrangement-crossing direction.

[0178] The range of the arrangement direction of the first high thermal conductive member 28 is not limited to the above. Fig.16 As shown, the first high thermal conductive member 28 may be provided only in the range corresponding to the heat generating portion 35 in the arrangement direction (see Fig.28 section line).

[0179] The first highly thermally conductive member 28 is sandwiched between the heater 22 and the heater holder 23 and is in close contact with these components by the pressing force of the pressing roller 21. The contact between the first highly thermally conductive member 28 and the heater 22 improves the heat transfer efficiency in the arrangement direction of the heaters 22.

[0180] Then, by arranging the first high thermal conductive member 28 at a position corresponding to the interval B of the heater 22 in the arrangement direction, the heat conduction efficiency in the interval B can be improved, and the amount of heat transferred to the position of the interval B in the arrangement direction can be increased, so that the temperature in the interval B in the arrangement direction can be increased. Therefore, the temperature unevenness in the arrangement direction of the heater 22 can be suppressed.

[0181] This can suppress uneven temperature in the arrangement direction of the fixing belt 20. Therefore, uneven fixing and uneven gloss of an image fixed on paper can be suppressed.

[0182] Alternatively, it is no longer necessary to perform unnecessary heating by the heater 22 in order to ensure sufficient fixing performance in the interval, thereby achieving energy saving of the fixing device 9. In addition, by providing the first high thermal conductive member 28 over the entire region of the heat generating portion 35 in the arrangement direction, the heat transfer efficiency of the heater 22 can be improved over the entire region of the main heating region of the heater 22 (i.e., the image forming region of the paper passing through the paper), and the temperature unevenness of the heater 22 and even the fixing belt 20 in the arrangement direction can be suppressed.

[0183] In particular, in the present embodiment, the combination of the first high thermal conductive component 28 and the impedance heating element 31 having the PTC characteristic can effectively suppress the excessive temperature rise caused by the non-paper passing area when the small-sized paper passes through the paper. That is, while suppressing the heat generated by the impedance heating element 31 in the non-paper passing area by utilizing the PTC characteristic, the heat of the non-paper passing area with the increased temperature can be effectively transferred to the side of the paper passing area, thereby effectively suppressing the excessive temperature rise generated in the non-paper passing area.

[0184] In addition, even in the vicinity of the interval B, since the heat generated by the interval B is small and the temperature thereof becomes low, it is preferable to arrange the first highly thermally conductive member 28. In particular, in the present embodiment, the first highly thermally conductive member 28 is provided over the entire region of the heat generating portion 35 in the arrangement direction. Thus, the temperature unevenness of the heater 22 (fixing belt 20) in the arrangement direction can be further suppressed.

[0185] Next, different embodiments of the fixing device will be described. Fig.17 As shown, the fixing device 9 of this embodiment includes a second highly thermally conductive member 36 between the heater holder 23 and the first highly thermally conductive member 28. The second highly thermally conductive member 36 is disposed in the stacking direction ( Fig.17 In the left-right direction of the device, it is arranged at a position different from the first high thermal conductive component 28.

[0186] More specifically, the second high thermally conductive component 36 is disposed overlapping the first high thermally conductive component 28. Fig.17 and Figure 2 Differently, the cross section shown is a cross section in which the second high thermal conductive member 36 in the arrangement direction is arranged and the thermistor 25 is not arranged.

[0187] The second high thermally conductive member 36 is made of a member having a higher thermal conductivity than the base material 30, such as graphene or graphite. In the present embodiment, the second high thermally conductive member 36 is formed of a graphite sheet having a thickness of 1 mm. However, the second high thermally conductive member 36 may be formed of a plate material such as aluminum, copper, or silver.

[0188] like Fig.18As shown, a plurality of second highly thermally conductive members 36 are arranged partially in the arrangement direction. The depth of the portion where the second highly thermally conductive member 36 is provided in the recess 23b of the heater holder 23 is set one step deeper than other portions.

[0189] A gap is provided between the second highly thermally conductive member 36 and the heater holder 23 on both sides in the arrangement direction. This can suppress heat transfer from the second highly thermally conductive member 36 to the heater holder 23, and the heater 22 can effectively heat the fixing belt 20. Fig.18 Omitted Fig.17 The guide component 26 is described.

[0190] like Fig.19 As shown, the second high thermal conductive member 36 (see the hatched portion) is disposed at a position corresponding to the interval B in the arrangement direction, and is disposed at a position overlapping at least a portion of the adjacent resistance heating element 31, and particularly in the present embodiment, is disposed over the entire area of ​​the interval B. Fig.19 (and the following Fig. 20 In FIG. 1 , the first highly thermally conductive member 28 is shown to be provided only in the region corresponding to the heat generating portion 35 in the arrangement direction, but the present invention is not limited to this case.

[0191] As shown in this embodiment, in addition to the first high thermal conductive member 28, by providing a second high thermal conductive member 36 at a position corresponding to the interval B in the arrangement direction and overlapping at least a portion of the adjacent resistance heating element 31, the heat transfer efficiency in the arrangement direction in the interval B can be particularly improved, and the temperature unevenness in the arrangement direction of the heater 22 can be further suppressed. In addition, it is most preferable as described later. Fig.28 As shown, at the position corresponding to the interval B, only the first highly thermally conductive member 89 and the second highly thermally conductive member 90 are provided in the entire region. Thus, at the position corresponding to the interval B, the heat transfer efficiency can be particularly improved compared to other regions.

[0192] In an embodiment of the present invention different from the above, the first highly thermally conductive member 28 and the second highly thermally conductive member 36 are formed of the above-mentioned graphene sheet. Thus, the first highly thermally conductive member 28 and the second highly thermally conductive member 36 having high thermal conductivity can be formed in a predetermined direction along the surface of the graphene, that is, not in the thickness direction but in the arrangement direction. Therefore, the temperature unevenness in the arrangement direction of the heater 22 and the fixing belt 20 can be effectively suppressed.

[0193] Graphene is a flake-like powder. Fig.31 As shown, graphene is composed of a planar hexagonal lattice structure of carbon atoms. Graphene sheets refer to sheet-like graphene, usually a single layer. A single layer of carbon may also contain impurities.

[0194] In addition, graphene may also have a fullerene structure. Fullerene structures are generally considered to be compounds in which the same number of carbon atoms form a cage-like condensed polycyclic structure of five-membered rings and six-membered rings, such as C60, C70 and C80 fullerenes or other closed cage structures with tri-coordinated carbon atoms.

[0195] Graphene sheets are artificial, and are produced, for example, by chemical vapor deposition (CVD). Commercially available graphene sheets can be used. The size and thickness of a graphene sheet, or the number of layers of a graphene sheet described later, etc., are measured, for example, by a transmission electron microscope (TEM).

[0196] In addition, graphite obtained by multi-layering graphene has large thermal conductivity anisotropy. Fig.32 As shown, graphite has a layer in which six-membered condensed ring layers of carbon atoms are spread out in a planar manner, and has a crystal structure in which the layers are stacked in multiple layers.

[0197] In this crystal structure, covalent bonds are formed between adjacent carbon atoms in the layer, and van der Waals bonds are formed between carbon atoms between layers. Moreover, covalent bonds have a stronger bonding force than van der Waals bonds, and the bonding within the layer and the bonding between the layers have a large anisotropy.

[0198] That is, by forming the first highly thermally conductive member 28 or the second highly thermally conductive member 36 from graphite, the heat transfer efficiency in the arrangement direction of the first highly thermally conductive member 28 or the second highly thermally conductive member 36 is greater than that in the thickness direction (i.e., the stacking direction of the members), and heat transfer to the heater holder 23 can be suppressed. Therefore, while effectively suppressing the temperature unevenness in the arrangement direction of the heater 22, the heat flowing out to the heater holder 23 side can be suppressed to a minimum. In addition, by forming the first highly thermally conductive member 28 or the second highly thermally conductive member 36 from graphite, the first highly thermally conductive member 28 or the second highly thermally conductive member 36 can have excellent heat resistance that does not oxidize up to about 700 degrees.

[0199] The properties and dimensions of the graphite sheet can be appropriately changed according to the functions required of the first highly thermally conductive member 28 or the second highly thermally conductive member 36. For example, by using high-purity graphite or single-crystal graphite, or by increasing the thickness of the graphite sheet, the anisotropy of thermal conductivity can be increased.

[0200] In order to increase the speed of the fixing device 9, a thin graphite sheet may be used to reduce the heat capacity of the fixing device 9. In addition, when the width of the fixing nip N or the heater 22 is large, the width of the first high thermal conductive member 28 or the second high thermal conductive member 36 in the arrangement direction may be increased accordingly.

[0201] From the viewpoint of improving mechanical strength, the number of layers of the graphite sheet is preferably 11 or more. In addition, the graphite sheet may partially include a single layer and a multilayer portion.

[0202] The second high thermally conductive member 36 may be provided at a position corresponding to the interval B (and thus the region C) in the arrangement direction, as long as it overlaps at least a portion of the adjacent resistance heating element 31. Fig.19 For example, Fig. 20 As shown, the second highly thermally conductive member 36A is provided so as to protrude toward both sides of the arrangement intersecting direction compared to the base material 30 in the arrangement intersecting direction.

[0203] The second highly thermally conductive member 36B is provided in the range where the resistance heating element 31 is provided in the direction intersecting the arrangement.

[0204] In addition, if Fig.21 As shown, in this embodiment, a gap in the thickness direction ( Fig.21 That is, in the recessed portion 23b (refer to the left and right direction) for arranging the heater 22, the first highly thermally conductive member 28, and the second highly thermally conductive member 36 of the heater holder 23, a gap (avoidance portion 23c) is formed. Fig.18 ), in a portion of the area other than the portion in the arrangement direction where the second high thermally conductive component 36 is provided, in a portion of the area in the direction crossing the arrangement, a relief portion 23c serving as a heat insulating layer is provided so that the depth of the recess 23b is deeper than that of other portions receiving the first high thermally conductive component 28.

[0205] Thus, the contact area between the heater holder 23 and the first highly thermally conductive member 28 can be minimized. Therefore, the heat transfer from the first highly thermally conductive member 28 to the heater holder 23 can be suppressed, and the heater 22 can effectively heat the fixing belt 20. In addition, in the cross section in the arrangement direction where the second highly thermally conductive member 36 is provided, as in the above embodiment, Fig.17 As shown, the second highly thermally conductive member 36 abuts against the heater holder 23 .

[0206] In addition, in particular, in the present embodiment, in the arrangement cross direction ( Fig.21 In the vertical direction of the first heat conductive member 28, the escape portion 23c is provided in the entire range where the resistance heating element 31 is provided. In this way, heat transfer from the first high thermal conductive member 28 to the heater holder 23 can be suppressed, and the heater 22 can effectively heat the fixing belt 20. In addition, as the heat insulating layer, in addition to the configuration of providing a space like the escape portion 23c, a configuration of providing a heat insulating member having a lower thermal conductivity than the heater holder 23 can also be used.

[0207] Furthermore, in the above description, the second highly thermally conductive member 36 is provided as a member different from the first highly thermally conductive member 28, but the present invention is not limited thereto. For example, the portion of the first highly thermally conductive member 28 corresponding to the interval B may be provided to be thicker than other portions.

[0208] Fig. 22 FIG. 2 is a top view of a heater of another example of the configuration of the first high thermal conductivity component. Fig. 22 As shown in FIG. 1 , at a position corresponding to the interval B in the arrangement direction, the first high thermal conductive component 89 may be provided only in the entire region. Fig. 22 For convenience, the impedance heating element 56 and the first high thermal conductive component 89 are placed in Fig. 22 The first high thermal conductive component 89 may be arranged at a portion of the arrangement cross direction of the impedance heating element 56, or as described later, Fig.23 It is set in such a way as to cover the entire cross direction of the arrangement.

[0209] Furthermore, if Fig.23 As shown, in addition to the position corresponding to the interval B in the arrangement direction, the first high thermal conductive component 89 can also be arranged across the impedance heating elements 56 on both sides with the interval B in the middle. The arrangement across the impedance heating elements 56 on both sides means that the first high thermal conductive component 89 overlaps at least partially with the impedance heating elements 56 on both sides in the arrangement direction.

[0210] Alternatively, the first high thermal conductive member 89 may be provided corresponding to all the intervals B of the heater 22, for example, Fig.23 As shown in the figure, the first highly thermally conductive member 89 may be provided only at a position corresponding to a portion of the interval B, such that the first highly thermally conductive member 89 is provided only at a position corresponding to a portion of the interval B. Here, provided at a position corresponding to the interval B in the arrangement direction means that at least a portion thereof overlaps with the interval B in the arrangement direction.

[0211] Here, the heater 63 in this embodiment is different from the Fig.39 Similarly to the resistance heating element 31 of the heater shown in FIG. 6 , a plurality of resistance heating elements 56 are arranged at intervals from each other in the longitudinal direction of the heater 63. However, in the configuration in which the plurality of resistance heating elements 56 are arranged at intervals from each other, the interval between the resistance heating elements 56 is Fig. 22 The temperature of the heater 63 in the divided region B tends to be lower than that in the portion where the resistance heating element 56 is arranged. Therefore, the temperature of the fixing belt 61 also becomes lower in the divided region B, and the temperature of the fixing belt 61 may become non-uniform in the longitudinal direction.

[0212] Therefore, in this embodiment, the first highly thermally conductive member 89 is provided to suppress the temperature drop in the divided area B and suppress the temperature variation in the longitudinal direction of the fixing belt 61. The first highly thermally conductive member 89 will be described in more detail below.

[0213] like Fig.25 As shown, the first high thermally conductive member 89 is disposed between the heater 63 and the support member 65 in the left-right direction of the figure, and is particularly sandwiched between the heater 63 and the heater holder 64. That is, one surface of the first high thermally conductive member 89 abuts against the back surface of the base material 55 of the heater 63, and the other surface of the first high thermally conductive member 89 (the surface on the opposite side to the one surface) abuts against the heater holder 64.

[0214] The support member 65 supports the heater holder 64, the first highly thermally conductive member 89, and the heater 63 by making the contact surfaces 65a1 of the two vertical portions 65a extending in the thickness direction of the heater 63 and the like contact with the heater holder 64. Fig.25 In the vertical direction of the fixing belt 61, the contact surface 65a1 is provided outside the range where the resistance heating element 56 is provided. Thus, heat transfer from the heater 63 to the support member 65 can be suppressed, and the heater 63 can heat the fixing belt 61 efficiently.

[0215] like Fig.26 As shown, the first high thermal conductive component 89 is a plate-shaped component with a certain thickness. For example, its thickness is set to 0.3 mm, its length in the long side direction is set to 222 mm, and its width in the direction crossing the length is set to 10 mm. In this embodiment, the first high thermal conductive component 89 is composed of a single plate, but it can also be composed of multiple components. Fig.26 In, omitted Fig.25 The guide component 66 described in .

[0216] The first highly thermally conductive member 89 is fitted into the recess 64b of the heater holder 64, and when the heater 63 is mounted from above, it is sandwiched and held by the heater holder 64 and the heater 63. In the present embodiment, the width of the first highly thermally conductive member 89 in the longitudinal direction is set to be substantially the same as the width of the heater 63 in the longitudinal direction.

[0217] The first high thermally conductive member 89 and the heater 63 are restricted from moving in the long-side direction by the two side walls (long-side direction restriction parts) 64b1 arranged in the direction intersecting the long-side direction of the recess 64b. In this way, by restricting the positional deviation of the first high thermally conductive member 89 in the long-side direction in the fixing device 60, the heat conduction efficiency can be improved relative to the target range in the long-side direction. In addition, the first high thermally conductive member 89 and the heater 63 are restricted from moving in the long-side direction by the two side walls (arrangement cross direction restriction parts) 64b2 arranged in the long-side direction of the recess 64b.

[0218] The range in the longitudinal direction (direction of arrow X) of the first highly thermally conductive member 89 is not limited to Fig.26 For example, Fig. 27 As shown, the first high thermal conductive member 89 may be arranged only in the range in the long side direction where the resistance heating element 56 is arranged (see Fig. 27 (the hatched part in the figure).

[0219] In addition, if Fig. 22 As in the example shown in FIG. 1 , the first high thermal conductive member 89 may be arranged only in the entire region at a position corresponding to the interval (divided region) B in the long side direction (direction of arrow X). Fig. 22 For convenience, the impedance heating element 56 and the first high thermal conductive component 89 are Fig. 22 Although they are displayed offset in the up and down directions, the two are arranged in approximately the same position in the longitudinal cross direction (arrow Y direction).

[0220] In addition, the first high thermal conductive member 89 may be disposed in a portion of the lengthwise intersecting direction (arrow Y direction) of the resistance heating element 56, or may be disposed in a portion of the lengthwise intersecting direction (arrow Y direction) of the resistance heating element 56. Fig.23 As shown in the example, the first high thermal conductive member 89 is arranged in the entire lengthwise direction (arrow Y direction) of the resistance heating element 56. Fig.23 As shown, in addition to the position corresponding to the interval B in the longitudinal direction, the first highly thermally conductive member 89 can be arranged so as to straddle the resistance heating elements 56 on both sides sandwiching the interval B.

[0221] The phrase "arranging the first high thermally conductive component 89 across the resistance heating elements 56 on both sides" means that the position of the first high thermally conductive component 89 in the longitudinal direction overlaps at least a portion of the resistance heating elements 56 on both sides. In addition, the first high thermally conductive component 89 may be arranged at a position corresponding to the entire interval B of the heater 63, or may be arranged as follows: Fig.23 As shown in the example, it is only arranged at a position corresponding to a portion of the interval B (in this case, one position). Here, "the first highly thermally conductive component 89 is arranged at a position corresponding to the interval B" means that the interval B overlaps with at least a portion of the first highly thermally conductive component 89 in the longitudinal direction.

[0222] The first highly thermally conductive member 89 is sandwiched between the heater 63 and the heater holder 64 by the pressing force of the pressing roller 62 and is in close contact with these members. The first highly thermally conductive member 89 is in contact with the heater 63, and the heat conduction efficiency in the long-side direction of the heater 63 is improved. Then, by arranging the first highly thermally conductive member 89 at a position corresponding to the interval B of the heater 63 in the long-side direction, the heat conduction efficiency in the interval B can be improved, and the amount of heat transferred to the interval B can be increased, so that the temperature in the interval B can be increased.

[0223] This can suppress temperature unevenness in the longitudinal direction of the heater 63, thereby suppressing temperature unevenness in the longitudinal direction of the fixing belt 61. As a result, it is possible to suppress fixing unevenness and gloss unevenness of an image fixed on paper.

[0224] In addition, in order to ensure sufficient fixing performance in the interval B, it is not necessary to increase the heat generation of the heater 63, and energy saving of the fixing device can be achieved. In particular, when the first high thermal conductivity member 89 is arranged in the entire area in the long side direction where the resistance heating element 56 is arranged, the heat transfer efficiency of the heater 63 can be improved in the entire area of ​​the main heating area of ​​the heater 63 (that is, the image forming area of ​​the paper passing through the paper), and the temperature unevenness in the long side direction of the heater 63 and even the fixing belt 61 can be suppressed.

[0225] Furthermore, by combining the first high thermal conductivity component 89 and the impedance heating element 56 having the PTC characteristic, it is possible to more effectively suppress excessive temperature rise caused by the non-passing paper area when small-sized paper passes through the paper. The PTC characteristic refers to a characteristic in which the resistance value increases when the temperature increases (the heater output power decreases when a stable voltage is applied). That is, by having the PTC characteristic of the impedance heating element 56, the heat generated by the impedance heating element 56 in the non-passing paper area can be effectively suppressed, and by the first high thermal conductivity component 89, the heat of the non-passing paper area with a temperature rise can be efficiently transferred to the passing paper area, so that the excessive temperature rise caused by the non-passing paper area can be effectively suppressed by their multiplication effect.

[0226] In addition, even in the vicinity of the interval B, since the heat generation of the interval B is small, the temperature of the heater 63 is lowered, and therefore it is preferable to arrange the first high thermal conductive member 89. Fig.24By disposing the first high thermally conductive member 89 in the position corresponding to the enlarged divided area C of the peripheral area of ​​the gap B shown in the figure, the heat transfer efficiency in the long-side direction of the gap B and its periphery can be improved, and the temperature unevenness in the long-side direction of the heater 63 can be more effectively suppressed. In addition, when the first high thermally conductive member 89 is disposed in the entire long-side direction of the area where all the resistance heating elements 56 are provided, the temperature unevenness in the long-side direction of the heater 63 (fixing belt 61) can be more reliably suppressed.

[0227] Next, still another embodiment of the fixing device will be described. Fig.25 The fixing device 60 shown in the figure has a second highly thermally conductive member 90 between the heater holder 64 and the first highly thermally conductive member 89. The second highly thermally conductive member 90 is arranged in the stacking direction ( Fig.25 In the left-right direction of the device, it is arranged at a position different from the first high thermal conductive component 89.

[0228] More specifically, the second high thermally conductive member 90 is provided overlapping the first high thermally conductive member 89. Fig.14 The embodiment shown is the same, with a temperature sensor (thermistor), but Fig.25 The cross section shown is without the temperature sensor 67 .

[0229] The second highly thermally conductive member 90 is made of a member having a higher thermal conductivity than the base material 55, such as graphene or graphite. In the present embodiment, the second highly thermally conductive member 90 is made of a graphite sheet having a thickness of 1 mm. However, the second highly thermally conductive member 90 may also be made of a plate material such as aluminum, copper, or silver.

[0230] like Fig.26 As shown, a plurality of second highly thermally conductive members 90 are arranged in the recess 64b of the heater holder 64, and there is a gap in the longitudinal direction between the second highly thermally conductive members 90. In the portion of the heater holder 64 where the second highly thermally conductive members 90 are provided, a recess one level deeper than other portions is formed.

[0231] The second highly thermally conductive member 90 is provided with gaps between both sides in the longitudinal direction and the heater holder 64. Therefore, heat transfer from the second highly thermally conductive member 90 to the heater holder 64 is suppressed, and the fixing belt 61 is effectively heated by the heater 63. Fig.26 In, omitted Fig.25 The guide component 66 described in .

[0232] like Fig. 27As shown in FIG. 1 , the second high thermally conductive component 90 (see the hatched portion) is arranged at a position corresponding to the interval B in the longitudinal direction (arrow X direction) and overlaps at least a portion of the adjacent resistance heating element 56. In particular, in this embodiment, the second high thermally conductive component 90 is arranged in the entire area of ​​the interval B. Fig. 27 (and the following Fig.29 ) shows a case where the first highly thermally conductive component 89 is disposed in the entire long side direction of the region where all the resistance heating elements 56 are disposed, but the arrangement range of the first highly thermally conductive component 89 is not limited to this.

[0233] As shown in this embodiment, in addition to the first high thermal conductive member 89, by arranging the second high thermal conductive member 90 at a position corresponding to the interval B in the long-side direction and overlapping at least a portion of the adjacent resistance heating element 56, the heat transfer efficiency in the long-side direction in the interval B can be further improved, and the temperature unevenness in the long-side direction of the heater 63 can be more effectively suppressed. In addition, it is most preferable that Fig.28 As shown, at the position corresponding to the interval B, the first highly thermally conductive member 89 and the second highly thermally conductive member 90 are provided only in the entire area thereof.

[0234] Thus, the heat transfer efficiency can be improved particularly at the position corresponding to the interval B compared to other regions. Fig.28 In the figure, for convenience, the impedance heating element 56 and the first high thermal conductive component 89 and the second high thermal conductive component 90 are shown staggered in the vertical direction of the figure, but they are arranged in approximately the same position in the longitudinal cross direction (arrow Y direction). However, this is not limited to this, and the first high thermal conductive component 89 and the second high thermal conductive component 90 can be arranged in a part of the longitudinal cross direction of the impedance heating element 56, or can be arranged to cover the entire longitudinal cross direction.

[0235] In addition, both the first highly thermally conductive member 89 and the second highly thermally conductive member 90 may be formed of the above-mentioned graphene sheet. In this case, the first highly thermally conductive member 89 and the second highly thermally conductive member 90 having high thermal conductivity can be formed in a predetermined direction along the surface of the graphene, that is, not in the thickness direction but in the long side direction. Therefore, the temperature unevenness in the long side direction of the heater 63 and the fixing belt 61 can be effectively suppressed.

[0236] Graphene is a flake-like powder. Fig.31 As shown, it consists of a planar hexagonal lattice structure of carbon atoms. Graphene sheet refers to a sheet of graphene, usually a single layer.

[0237] In addition, graphene sheets can contain impurities in a single layer of carbon or have a fullerene structure. Fullerene structures are generally considered to be compounds formed by the same number of carbon atoms forming a cage-like condensed polycyclic body of five-membered rings and six-membered rings, such as C60, C70 and C80 fullerenes or other closed cage structures with tri-coordinated carbon atoms.

[0238] Graphene sheets are artificial, and are produced, for example, by chemical vapor deposition (CVD). Commercially available graphene sheets can be used. The size and thickness of a graphene sheet, or the number of layers of a graphene sheet described later, etc., are measured, for example, by a transmission electron microscope (TEM).

[0239] In addition, graphite after multi-layering of graphene has large thermal conductivity anisotropy. Fig.32 As shown, graphite has a layer in which six-membered condensed ring layers of carbon atoms are spread out in a planar manner, and has a crystal structure in which the layers are stacked in multiple layers.

[0240] In the crystal structure, covalent bonds are formed between carbon atoms in the layer, and van der Waals bonds are formed between carbon atoms between layers. Moreover, covalent bonds have a greater bonding force than van der Waals bonds, and the bonding within the layer and the bonding between the layers have a large anisotropy. That is, by forming the first high thermal conductive component 89 or the second high thermal conductive component 90 from graphite, the heat transfer efficiency in the long side direction of the first high thermal conductive component 89 or the second high thermal conductive component 90 is greater than that in the thickness direction (i.e., the stacking direction of the components), and heat transfer to the heater holder 64 can be suppressed.

[0241] Therefore, while effectively suppressing the temperature unevenness in the longitudinal direction of the heater 63, the heat flowing out to the heater holder 64 can be suppressed to a minimum. In addition, by forming the first high thermally conductive member 89 or the second high thermally conductive member 90 from graphite, the first high thermally conductive member 89 or the second high thermally conductive member 90 can have excellent heat resistance that does not oxidize up to about 700 degrees.

[0242] The properties and dimensions of the graphite sheet can be appropriately changed according to the functions required of the first highly thermally conductive member 89 or the second highly thermally conductive member 90. For example, by using high-purity graphite or single-crystal graphite, or increasing the thickness of the graphite sheet, the anisotropy of thermal conductivity can be increased.

[0243] In addition, in order to increase the speed of the fixing device, a thin graphite sheet may be used to reduce the heat capacity of the fixing device. In addition, when the width of the fixing nip N and the heater 63 is large, the width of the first high thermal conductive member 89 or the second high thermal conductive member 90 in the long side direction may be increased accordingly.

[0244] From the viewpoint of improving mechanical strength, the number of layers of the graphite sheet is preferably 11 or more. In addition, the graphite sheet may partially include a single layer and a multilayer portion.

[0245] The second high thermally conductive member 90 may be provided at a position corresponding to the interval B (further expanding the divided area C) in the longitudinal direction, as long as it overlaps at least a portion of the adjacent resistance heating element 56. Fig. 27 For example, Fig.29 In the illustrated example, the second highly thermally conductive member 90A may be provided so as to protrude from the base material 55 to both sides in the longitudinally intersecting direction (the direction of arrow Y).

[0246] In addition, the second highly thermally conductive member 90B may be provided in the range where the resistance heating element 56 is provided in the longitudinal intersecting direction. In addition, the second highly thermally conductive member 90C may be provided in a part of the interval B.

[0247] In addition, Fig.30 In the other embodiment shown in the figure, a gap in the thickness direction ( Fig.30 That is, in the recessed portion 64b (refer to Fig.26 ) is provided in a part of the area, and a avoidance portion 64c is provided as a heat insulating layer.

[0248] The escape portion 64c is provided in a region where the second high thermal conductive member 90 is provided ( Fig.30 In addition, the escape portion 64c is formed by making the depth of the recessed portion 64b of the heater holder 64 deeper than other portions.

[0249] Thus, the contact area between the heater holder 64 and the first highly thermally conductive member 89 can be minimized, so that heat transfer from the first highly thermally conductive member 89 to the heater holder 64 can be suppressed, and the fixing belt 61 can be effectively heated by the heater 63. Fig.25 As in the illustrated embodiment, the second highly thermally conductive member 90 is in contact with the heater holder 64 .

[0250] In addition, in the present embodiment, the escape portion 64c is Fig.30The first high thermal conductive member 89 is provided over the entire area of ​​the range where the resistance heating element 56 is provided in the vertical direction (in the vertical direction). Thus, the heat transfer from the first high thermal conductive member 89 to the heater holder 64 can be effectively suppressed, and the heating efficiency of the fixing belt 61 by the heater 63 can be improved. In addition, as the heat insulating layer, in addition to the configuration of providing a space like the escape portion 64c, a configuration of providing a heat insulating member having a lower thermal conductivity than the heater holder 64 can also be used.

[0251] In addition, in the present embodiment, the second highly thermally conductive member 90 is provided as a member different from the first highly thermally conductive member 89, but the present invention is not limited thereto. For example, the thickness of the portion of the first highly thermally conductive member 89 corresponding to the interval B may be made thicker than the thickness of other portions, so that the first highly thermally conductive member 89 also functions as the second highly thermally conductive member 90.

[0252] In the above description, the present invention is applied to a fixing device as an example of a belt-type heating device (gripping portion forming device). However, the present invention is not limited to the fixing device, and may also be a heating device such as a drying device for drying liquid such as ink applied to paper, a laminating machine for hot-pressing a film material as a covering member to the surface of a sheet such as paper, a heat sealer for hot-pressing a sealing portion of a packaging material, etc. In addition, the present invention may also be applied to a gripping portion forming device that does not have a heating source such as a heater.

[0253] (●Modified embodiment of fixing device)

[0254] Next, refer to Figure 33 to Figure 43 Modified embodiments of the fixing device 9 will be described. Fig.33 This is a diagram showing a changed arrangement of thermistors.

[0255] In the present embodiment, the thermistor 25 is arranged on the upstream side of the center position NA of the fixing nip N in the rotation direction of the fixing belt 20 in the arrangement cross direction, in other words, on the inlet side of the fixing nip N. Since the inlet side of the fixing nip N is a region that is particularly susceptible to heat being taken away by the paper P, the thermistor 25 detects the temperature of this portion, thereby ensuring the fixing performance of the fixing device 9 and effectively suppressing the fixing offset.

[0256] Fig.34 The fixing device 9 shown in the figure is provided with a pressing roller 44 on the side opposite to the fixing belt 20 and the pressure roller 21. The pressing roller 44 is a rotating member that rotates opposite to the fixing belt 20 as a rotating member. The pressing roller 44 and the heater 22 are configured to heat the fixing belt 20 while sandwiching it.

[0257] On the other hand, on the pressure roller 21 side, a nip forming member 45 is disposed on the inner periphery of the fixing belt 20. The nip forming member 45 is supported by the support 24. The nip forming member 45 and the pressure roller 21 sandwich the fixing belt 20 to form a nip N.

[0258] Then, in Fig.35 In the fixing device 9 shown in FIG. 1 , the aforementioned pressing roller 44 is omitted. In order to ensure the contact length of the fixing belt 20 and the heater 22 in the circumferential direction, the heater 22 is formed into an arc shape along the curvature of the fixing belt 20. Fig.34 The fixing device 9 shown has the same structure.

[0259] Finally, Fig.36 The fixing device 9 shown in the figure will be described. The fixing device 9 is composed of a heating unit 92, a fixing roller 93 as a fixing member, and a pressure unit 94 as an opposing member.

[0260] The heating assembly 92 includes the heater 22, the heater holder 23, the support member 24, the heating belt 120 as a rotating member, etc., which are described in the previous embodiment. The fixing roller 93 is a rotating member that rotates opposite to the heating belt 120 as a rotating member. The fixing roller 93 is composed of a solid iron core rod 93a, an elastic layer 93b formed on the surface of the core rod 93a, and a release layer 93c formed on the outside of the elastic layer 93b.

[0261] In addition, a pressure unit 94 is provided on the opposite side of the heating unit 92 to the fixing roller 93. The pressure unit 94 is provided with a nip forming member 95 and a support 96, and a pressure belt 97 is rotatably provided including the nip forming member 95 and the support 96. Then, the paper P is passed through the fixing nip N2 between the pressure belt 97 and the pressure roller 93, and is heated and pressed to fix the image.

[0262] Even in the above Figure 34 to Figure 36 In the fixing device of the embodiment, the heat generation of the heater 22 is reduced in the divided area B between the resistance heating elements 31 of the heater 22. Therefore, as in the above embodiment, by providing the temperature detection element of the temperature detection member at the position corresponding to the divided area B of the heater 22, the portion corresponding to the divided area of ​​the rotating member can be fully heated. Thus, the fixability of the image can be fully ensured, and the occurrence of undesirable conditions such as fixing offset can be prevented.

[0263] In addition, the present invention is not limited to the fixing device described above, and can also be applied to a drying device for drying ink applied to paper, and further, can also be applied to a heating device such as a heat-pressing device such as a laminator for heat-pressing a film material as a covering member to the surface of a sheet such as paper, and a heat sealer for heat-pressing a sealing portion of a packaging material. By applying the present invention to such a device, the portion of the rotating member corresponding to the divided area can be fully heated.

[0264] The image forming apparatus according to the present invention is not limited to Figure 1 The color image forming device shown in the figure may also be a black and white image forming device or a copier, a printer, a fax machine or a multi-function peripheral device thereof. Fig.37 As shown, the image forming apparatus 100 of this embodiment includes an image forming unit 50 including a photosensitive drum, etc., a paper conveying unit including a pair of timing rollers 15, etc., a paper feeding device 7, a fixing device 9, a paper discharge device 10, and a reading unit 51. The paper feeding device 7 includes a plurality of paper feeding trays, each of which accommodates paper of different sizes.

[0265] The reading unit 51 reads an image of the document Q. The reading unit 51 generates image data from the read image. The paper feed device 7 stores a plurality of sheets of paper P and feeds the sheets of paper P to a transport path. The timing roller 15 feeds the sheets of paper P on the transport path to the image forming mechanism 50 .

[0266] The image forming mechanism 50 forms a toner image on the paper P. Specifically, the image forming mechanism 50 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a static eliminating device. The toner image represents an image of the original Q, for example.

[0267] The fixing device 9 heats and pressurizes the toner image to fix the toner image on the paper P. The paper P on which the toner image is fixed is conveyed to the paper discharge device 10 by conveying rollers and the like. The paper discharge device 10 discharges the paper P to the outside of the image forming apparatus 100 .

[0268] Next, the fixing device 9 of the present embodiment will be described. The description of the common configurations with the fixing device of the above-described embodiment will be appropriately omitted.

[0269] like Fig.38 As shown, the fixing device 9 includes a fixing belt 20, a pressure roller 21, a heater 22, a heater holder 23, a support member 24, a thermistor 25, etc. A fixing nip N is formed between the fixing belt 20 and the pressure roller 21. The nip width of the fixing nip N is 10 mm, and the linear speed of the fixing device 9 is 240 mm / s.

[0270] The fixing belt 20 has a polyimide base and a release layer, and does not have an elastic layer. The release layer is made of a heat-resistant film material such as fluorine resin. The outer diameter of the fixing belt 20 is about 24 mm.

[0271] The pressure roller 21 includes a core shaft 21a, an elastic layer 21b, and a release layer 21c. The outer diameter of the pressure roller 21 is formed to be 24 to 30 mm, and the thickness of the elastic layer 21b is formed to be 3 to 4 mm.

[0272] The heater 22 includes a base material, a heat insulating layer, a conductor layer including a resistance heating element, and an insulating layer, and the overall thickness is 1 mm. The width Y of the heater 22 in the direction intersecting the arrangement is 13 mm.

[0273] like Fig.39 As shown, the conductor layer of the heater 22 includes a plurality of resistance heating elements 31, a power supply line 33, and electrode portions 34A to 34C. Fig.39 As shown in the enlarged view of FIG. 1 , a plurality of divided regions B (wherein, in Fig.39 In the figure, the divided area B is only shown within the range of the enlarged view, but in fact, the divided area B is provided between all the resistance heating elements 31.

[0274] The three heating parts 35A to 35C are formed by the impedance heating element 31. When the electrode parts 34A and 34B are energized, the heating parts 35A and 35C generate heat. When the electrode parts 34A and 34C are energized, the heating part 35B generates heat. For example, when a fixing operation is performed on a small-sized paper, the heating part 35B generates heat, and when a fixing operation is performed on a large-sized paper, all the heating parts generate heat.

[0275] like Fig.40 As shown, the heater holder 23 holds the heater 22 in its recess 23b. The recess 23d is provided on the heater 22 side of the heater holder 23. The recess 23b includes a surface 23b3 substantially parallel to the base material 30 and recessed on the support member 24 side more than other surfaces of the heater 22, a wall portion 23b1 provided on the inner side of the heater holder 23 on both sides (or one side) of the arrangement direction of the heater holder 23, and a wall portion 23b2 provided on the inner side of the heater holder 23 on both sides of the arrangement cross direction.

[0276] The heater holder 23 has a guide member 26. The heater holder 23 is formed of LCP (Liquid Crystal Polymer).

[0277] like Fig.41As shown, the connector 160 includes a housing made of resin (eg, LCP) and a plurality of contact terminals provided in the housing, etc. The connector 160 is mounted so as to sandwich the heater 22 and the heater holder 23 from both the front side and the back side.

[0278] In this state, the heating component 35 and the power source provided in the image forming apparatus are electrically connected through the connector 160 by the contact (compression bonding) of each contact terminal with each electrode portion of the heater 22. Thus, it is possible to supply power from the power source to the heating component 35. In addition, in order to ensure the connection with the connector 160, at least a part of each electrode portion 34 is not covered by the insulating layer and is exposed.

[0279] The flanges 53 are provided on both sides of the fixing belt 20 in the arrangement direction, and hold both ends of the fixing belt 20 from the inner side of the belt. The flanges 53 are fixed to the frame of the fixing device 9. The flanges 53 are inserted into both ends of the support member 24 (refer to Fig.41 53).

[0280] The direction in which the connector 160 is mounted relative to the heater 22 and the heater holder 23 is the direction in which the heaters are arranged (see Fig.41 When the connector 160 is mounted on the heater holder 23, the convex portion provided on one of the connector 160 and the heater holder 23 engages with the concave portion provided on the other, and the convex portion can move relatively in the concave portion. In addition, the connector 160 is mounted on the heater 22 and the heater holder 23 on either side of the arrangement direction, that is, on the opposite side to the side where the drive motor of the pressure roller 21 is provided.

[0281] like Fig.42 As shown in the figure, thermistors 25 are respectively provided on the central side and the end side of the arrangement direction of the fixing belt 20, facing the inner peripheral surface of the fixing belt 20. The heater 22 is controlled according to the respective temperatures of the central side and the end side of the arrangement direction of the fixing belt 20 detected by the thermistors 25. In addition, any one of these thermistors 25 is provided at a position corresponding to the division area between the resistance heating elements of the heater 22, as in the above-mentioned embodiment.

[0282] Thermostats 27 are provided facing the inner peripheral surface of the fixing belt 20 at the center and end of the fixing belt 20 in the arrangement direction. When the temperature of the fixing belt 20 detected by the thermostat 27 exceeds a predetermined threshold, power supply to the heater 22 is stopped.

[0283] Flanges 53 for holding the respective ends of the fixing belt 20 are provided at both ends in the arrangement direction of the fixing belt 20. The flanges 53 are formed of LCP (liquid crystal polymer).

[0284] like Fig.43 As shown in FIG. 1 , a slide groove 53a is provided on the flange 53. The slide groove 53a extends in the contact and separation direction of the fixing belt 20 relative to the pressure roller 21. The engaging portion of the frame of the fixing device 9 engages with the slide groove 53a. By the relative movement of the engaging portion in the slide groove 53a, the fixing belt 20 can move in the contact and separation direction relative to the pressure roller 21.

[0285] In the above fixing device 9, by providing the temperature detection element of the thermistor 25 at the position corresponding to the divided area B of the heater 22, the portion corresponding to the divided area of ​​the fixing belt 20 can be sufficiently heated. Thus, the fixability of the image can be fully ensured, and the occurrence of defects such as fixing offset can be prevented.

[0286] In particular, in the case of an image forming apparatus that performs image forming operation using a single color toner, thermal offset is relatively less likely to occur compared to an image forming apparatus that performs image forming operation using a multi-color toner. Therefore, even if the control of the heating member is performed based on the detection result of the temperature detection element arranged at the position corresponding to the divided area as in the present invention, there is an advantage that thermal offset is relatively less likely to occur in an image forming apparatus that uses a single color toner.

[0287] Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications are possible. For example, the separation plate 310 may be configured to be able to move toward the fixing belt 20 and away from the fixing belt 20. In addition to being able to rotate as in the above embodiment, the separation plate 310 may also be configured to be able to move in parallel toward the fixing belt 20 and away from the fixing belt 20 while maintaining a parallel state with the heater holder 23.

[0288] In addition, the separation plate 310 may be fixed and immovable. That is, the separation plate 310 only needs to have a front end portion 311 that can contact the paper P as a conveyed body and is non-contact with the fixing belt 20, and a contact portion 313 that contacts the fixing belt 20 to keep the distance between the front end portion 311 and the fixing belt 20 at a predetermined size.

[0289] In the above embodiment, the fixing belt 20 of the fixing device 60 is used as an example of an endless belt, but the endless belt may be a photoreceptor belt. That is, in an image forming device that transfers a toner image carried on the photoreceptor belt as an image carrier to a recording medium as a transported body, the recording medium is separated from the photoreceptor belt by the separation plate.

[0290] In addition, the endless belt can also be used as an image carrier. Figure 1The intermediate transfer belt 11 is used for the recording medium conveyed through the clamping portion between the intermediate transfer belt 11 and the secondary transfer roller 13. That is, the recording medium conveyed through the clamping portion between the intermediate transfer belt 11 and the secondary transfer roller 13 is separated from the intermediate transfer belt 11 by the above-mentioned separation plate. Similarly, the endless belt may also be an intermediate transfer belt used in an image forming apparatus of an inkjet type. In addition, in other image forming apparatuses of an inkjet type, even in the case of a configuration in which a pressure member is pressed against a clamping portion forming member via an endless belt to form a clamping portion, and a conveyed object is conveyed through the clamping portion, the above-mentioned separation plate can be used to separate the conveyed object from the endless belt after passing through the clamping portion.

[0291] <Notes>

[0292] Hereinafter, preferred embodiments of the present invention will be described.

[0293] <Method 1>

[0294] A clamping portion forming unit, characterized by comprising:

[0295] A rotatable flexible endless belt;

[0296] a clamping portion forming member configured to be in contact with the inner peripheral surface of the endless belt;

[0297] a pressurizing member that forms a clamping portion by press-bonding the annular belt with the clamping portion forming member, and

[0298] guide members for guiding both ends of the endless belt, and

[0299] The transported object is transported through the clamping portion shown.

[0300] A separation member is provided for separating the conveyed object passing through the clamping portion from the endless belt.

[0301] The separation member includes a non-contact portion that does not come into contact with the endless belt, and a contact portion that comes into contact with the endless belt to maintain a distance between the non-contact portion and the endless belt at a predetermined size.

[0302] <Method 2>

[0303] The clamping portion forming unit according to embodiment 1 is characterized in that:

[0304] The separation component is configured to be movable in directions approaching and moving away from the endless belt, and is provided with a movement limiting mechanism having a first limiting portion that determines the movement position in the approaching direction and a second limiting portion that determines the movement position in the moving away direction.

[0305] <Method 3>

[0306] The clamping portion forming unit according to embodiment 2 is characterized in that:

[0307] The separation member is urged in the approaching direction by an urging mechanism.

[0308] <Method 4>

[0309] The clamping portion forming unit according to embodiment 3 is characterized in that:

[0310] The clamping portion forming unit is configured relative to the pressurizing component to be able to move between an approach position where the clamping portion is pressurized by the pressurizing component and a separation position after the clamping portion is depressurized. When the separation component is restricted in movement by the first limiting portion, the clamping portion forming component can move to the separation position.

[0311] <Method 5>

[0312] The clamping portion forming unit according to any one of Modes 2 to 4 is characterized in that:

[0313] When the separation member moves in the separating direction, the movement is restricted by the second restriction portion before the separation member comes into contact with the pressing member.

[0314] <Method 6>

[0315] The clamping portion forming unit according to any one of Modes 2 to 5 is characterized in that:

[0316] The separation member is composed of a separation plate movably supported between a pair of left and right side plates, and the movement restriction mechanism is disposed between the separation plate and the side plates.

[0317] <Method 7>

[0318] The clamping portion forming unit according to embodiment 6 is characterized in that:

[0319] The movement limiting mechanism is composed of a movable limiting plate formed at the end of the separation plate and a movement limiting hole formed in the side plate. The first limiting portion is formed by one end of the movement limiting hole, and the second limiting portion is formed by the other end of the movement limiting hole.

[0320] <Method 8>

[0321] The clamping portion forming unit according to any one of the aspects 1 to 7 is characterized in that:

[0322] The contact portion is provided outside a passage area of ​​the transported object.

[0323] <Method 9>

[0324] The clamping portion forming unit according to any one of the aspects 1 to 8 is characterized in that:

[0325] The heater provided on the clamping portion forming member for heating the endless belt is divided into at least three heaters, namely, end heaters for heating both end portions of the endless belt and a central heater for heating the central portion.

[0326] <Method 10>

[0327] An image forming device, characterized in that:

[0328] A clamping portion forming unit according to any one of claims 1 to 9.

Claims

1. A clamping portion forming unit, characterized in that include: A rotatable flexible endless belt; a clamping portion forming member configured to be in contact with the inner peripheral surface of the endless belt; a pressurizing member that forms a clamping portion by press-bonding the annular belt with the clamping portion forming member, and guide members for guiding both ends of the endless belt, and The transported object is transported through the clamping portion shown. A separation member is provided for separating the conveyed object passing through the clamping portion from the endless belt. The separation member includes a non-contact portion that does not contact the endless belt, and a contact portion that contacts the endless belt to maintain a distance between the non-contact portion and the endless belt at a predetermined size. The separation member is configured to be movable in a direction approaching and moving away from the endless belt, and is provided with a movement limiting mechanism having a first limiting portion for determining a moving position in the approaching direction and a second limiting portion for determining a moving position in the moving away direction, The separation component is urged in the approaching direction by the urging mechanism, The clamping portion forming unit is configured relative to the pressurizing component to be able to move between an approach position where the clamping portion is pressurized by the pressurizing component and a separation position after the clamping portion is depressurized. When the separation component is restricted in movement by the first limiting portion, the clamping portion forming component can move to the separation position.

2. The clamping portion forming unit according to claim 1, characterized in that: When the separation member moves in the separating direction, the movement is restricted by the second restriction portion before the separation member comes into contact with the pressing member.

3. The clamping portion forming unit according to claim 1 or 2, characterized in that: The separation member is composed of a separation plate movably supported between a pair of left and right side plates, and the movement restriction mechanism is disposed between the separation plate and the side plates.

4. The clamping portion forming unit according to claim 3, characterized in that: The movement limiting mechanism is composed of a movable limiting plate formed at the end of the separation plate and a movement limiting hole formed in the side plate. The first limiting portion is formed by one end of the movement limiting hole, and the second limiting portion is formed by the other end of the movement limiting hole.

5. The clamping portion forming unit according to claim 1 or 2, characterized in that: The contact portion is provided outside a passage area of ​​the transported object.

6. The clamping portion forming unit according to claim 1 or 2, characterized in that: The heater provided on the clamping portion forming member for heating the endless belt is divided into at least three heaters, namely, end heaters for heating both end portions of the endless belt and a central heater for heating the central portion.

7. An image forming device, characterized in that: A clamping portion forming unit according to any one of claims 1 to 6.

Images