Heating device and image forming device

Abstract

The heating device and image forming device of the present invention are intended to suppress the inconvenience caused by the uneven temperature of the heating component due to the heat generated by the conductor pattern. The heating device comprises an endless fixing belt (20), a pressure roller (21) that contacts the fixing belt (20) to form a fixing nip (N), a strip-shaped heater (22) that heats the fixing belt (20), and a pressure mechanism (80A) and (80B) for the fixing belt (20) or the pressure roller (21) to form a fixing nip (N) between the fixing belt (20) and the pressure roller (21), wherein the pressure mechanism (80A) and (80B) make the pressure on the side with a larger heat generation in the longitudinal direction of the heater (22) relatively smaller than the pressure on the side with a smaller heat generation.

Description

Technical Field

[0001] The invention relates to a heating device and an image forming device. Background Art

[0002] As a heating device mounted in an image forming apparatus such as a copier or a printer, a fixing device that fixes toner on paper by heat and a drying device that dries ink on paper are known.

[0003] For example, the fixing device disclosed in Patent Document 1 below includes a heating member (heater) in which a heating element, an electric contact, and a conductor pattern for electrically connecting them are provided on a long substrate.

[0004] However, in a heating component having such a conductor pattern on a substrate, when the heating element is heated, the conductor pattern will also generate slight heat due to the conduction of electricity to the conductor pattern. Therefore, strictly speaking, the heat distribution of the entire heating component will be affected by the heat generated by the conductor pattern.

[0005] Therefore, the temperature distribution of the heating member may be uneven due to the heat distribution of the conductor pattern. Therefore, in a device having such a heating member, a countermeasure is required to suppress the malfunction caused by the uneven temperature of the heating member due to the heat of the conductor pattern.

[0006] [Patent Document 1] (Japan) Patent Publication No. 2016-62024 Summary of the invention

[0007] In order to solve the above-mentioned problems, the technical solution of the present invention relates to a heating device, which includes: a rotating part; an opposing part that contacts the rotating part to form a clamping part; a heating part that heats the rotating part, and a pressurizing mechanism that presses at least one of the rotating part and the opposing part and presses it against the other side. The heating device is characterized in that the pressurizing mechanism makes the pressurizing force on the side of the heating part with a larger heat generation in the longitudinal direction relatively smaller than the pressurizing force on the side with a smaller heat generation.

[0008] According to the present invention, it is possible to suppress a malfunction caused by a temperature deviation between one side and the other side in the longitudinal direction of the heating member. 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 the fixing device.

[0012] Figure 4 Shown is an exploded perspective view of the fixing device.

[0013] Figure 5 Shown is a perspective view of the heating unit.

[0014] Figure 6 Shown is an exploded perspective view of the heating unit.

[0015] Figure 7 Shown is a top view of the heater.

[0016] Figure 8 Shown is an exploded perspective view of the heater.

[0017] Fig. 9 Shown is a perspective view of a state in which the connector is connected to the heater.

[0018] Fig.10 Shown is a diagram of the power supply to the heater.

[0019] Fig.11 Shown is a diagram of a typical current flow path.

[0020] Fig.12 The diagram shows the current path when unexpected current diversion occurs.

[0021] Fig.13 FIG. 1 is a graph showing the amount of heat generated by the power supply line for each block when an unexpected current diversion occurs.

[0022] Fig.14 Shown is Fig.13 A diagram of the total heat generated by the power supply lines of each block in the case.

[0023] Fig.15 The graph shows the amount of heat generated by the power supply line for each block when all the heat generating parts are energized.

[0024] Fig.16 Shown is Fig.15 A diagram of the total heat generated by the power supply lines of each block in the case.

[0025] Fig.17 The diagram shows the pressure of the pressurizing mechanism under constant pressurizing conditions.

[0026] Fig.18 The figure shows the state of a small-size paper when it passes through the paper. The upper side is the heater, the center is the position relationship diagram of the fixing device in the length direction, and the lower side is the temperature distribution diagram in the length direction of the fixing belt.

[0027] Fig.19The figure shows the state when a large-size paper passes, with the upper side showing the positional relationship of the heater and the center showing the longitudinal direction of the fixing device, and the lower side showing the temperature distribution of the fixing belt in the longitudinal direction.

[0028] Fig. 20 The figure shows the timing of changing the pressurization conditions.

[0029] Fig.21 Shown is with Fig. 20 Flowchart of timing for changing pressurization conditions in different embodiments.

[0030] Fig. 22 The figure shows a fixing device having a plurality of temperature detection mechanisms arranged in the longitudinal direction, wherein the upper side shows the heater, the center shows the positional relationship in the longitudinal direction of the fixing device, and the lower side shows the temperature distribution in the longitudinal direction of the fixing belt.

[0031] Fig.23 The flowchart shown is a timing for changing the pressurization conditions based on the detection result of the temperature detection means.

[0032] Fig.24 The figure shows a fixing device having a plurality of temperature detection mechanisms arranged in the longitudinal direction, wherein the upper side shows the heater, the center shows the positional relationship in the longitudinal direction of the fixing device, and the lower side shows the temperature distribution in the longitudinal direction of the fixing belt.

[0033] Fig.25 The flowchart shown is a timing for changing the pressurization conditions based on the detection result of the temperature detection means.

[0034] FIG. 26( a ) and FIG. 26( b ) are diagrams showing a pressurizing mechanism under equal pressurizing conditions.

[0035] FIG. 27( a ) and FIG. 27 ( b ) are diagrams showing the pressurizing mechanism under the first pressurizing condition.

[0036] FIG. 28( a ) and FIG. 28( b ) are diagrams showing the pressurizing mechanism under the second pressurizing condition.

[0037] FIG. 29( a ) and FIG. 29( b ) are diagrams showing pressurizing mechanisms according to different embodiments.

[0038] Fig.30 Shown is a diagram of a pressurizing mechanism according to another different embodiment.

[0039] Fig.31 FIG. 1 is a diagram showing a fixing device provided with a pressing mechanism for pressing a pressing roller.

[0040] Fig.32 Shown is a top view of the short side dimensions of the heater and the short side dimensions of the impedance heating element.

[0041] 33(a) and 33(b) are top views showing modified examples of the heater, respectively.

[0042] Fig.34 The figure shows the structure of other fixing devices.

[0043] Fig.35 Shown is a diagram showing the structure of another fixing device.

[0044] Fig.36 Shown is a diagram showing the structure of another fixing device.

[0045] Fig.37 Shown is a diagram of the power supply for heaters of different configurations.

[0046] Fig.38 Shown is Fig.37 A graph showing the amount of heat generated by the power supply line for each block when an unexpected current diversion occurs in the heater.

[0047] Fig.39 Shown is Fig.38 A diagram of the total heat generated by the power supply lines of each block in the case.

[0048] Fig.40 Shown is Fig.37 A diagram showing the amount of heat generated by the power supply line of each block when all the heat generating parts of the heater are energized.

[0049] Fig.41 Shown is Fig.40 A diagram of the total heat generated by the power supply lines of each block in the case. DETAILED DESCRIPTION

[0050] Hereinafter, the embodiments of the present invention will be described with reference to the accompanying drawings. In each figure, the same or equivalent parts are given the same symbols, and their detailed description is appropriately omitted. Hereinafter, in the description of each embodiment, as a heating device, a fixing device that fixes the toner by heat is described.

[0051] exist Figure 1 The monochromatic image forming apparatus 1 shown in the figure is provided with a photosensitive drum 10. The photosensitive drum 10 is a drum-shaped rotating body capable of carrying a toner as a developer on the surface, and rotates in the arrow direction of the figure. Around the photosensitive drum 10, there are a charging roller 11 for uniformly charging the surface of the photosensitive drum 10, a developing device 12 including a developing roller 7 for supplying toner to the surface of the photosensitive drum 10, a cleaning blade 13 for cleaning the surface of the photosensitive drum 10, and the like.

[0052] An exposure unit 3 is disposed above the process unit 2 . The exposure unit 3 emits laser light Lb based on image data and irradiates the surface of the photosensitive drum 10 via a reflection mirror 14 .

[0053] In addition, a transfer mechanism 15 having a transfer charger is arranged at a position facing the photosensitive drum 10. The transfer mechanism 15 transfers the image on the surface of the photosensitive drum 10 to the paper P.

[0054] The paper feed unit 4 is located at the bottom of the image forming apparatus 1 and includes a paper feed cassette 16 for storing paper P as a recording medium, a paper feed roller 17 for delivering the paper P from the paper feed cassette 16 to the conveyance path 5, etc. A registration roller 18 is disposed downstream of the paper feed roller 17 in the conveyance direction.

[0055] The fixing device 9 includes a fixing belt 20 heated by a heating member described later, a pressure roller 21 capable of applying pressure to the fixing belt 20 , and the like.

[0056] Next, refer to Figure 1 The basic operation of the above-mentioned image forming apparatus 1 will be described.

[0057] When the printing operation (image forming operation) starts, the photosensitive drum 10 is first charged on its surface by the charging roller 11. Then, the laser beam Lb is irradiated from the exposure unit 3 according to the image data, and the potential of the irradiated portion decreases to form an electrostatic latent image. In the photosensitive drum 10 formed with the electrostatic latent image, the toner is supplied from the developing device 12 to the surface portion and visualized as a toner image (developer image). Then, the toner and the like remaining in the photosensitive drum 10 after the transfer are removed by the cleaning blade / cleaning blade 13.

[0058] On the other hand, when the printing operation starts, at the lower part of the image forming apparatus 1 , the paper P accommodated in the paper feed cassette 16 is fed to the conveyance path 5 by the rotational drive of the paper feed roller 17 of the paper feed unit 4 .

[0059] The paper P fed into the conveying path 5 is timed by the registration roller 18, and is conveyed toward the transfer mechanism 15 and the opposing portion of the photosensitive drum 10, i.e., the transfer portion, at a timing that the paper P faces the colorant image on the surface of the photosensitive drum 10, and the colorant image is transferred by applying a transfer bias of the transfer mechanism 15.

[0060] The paper P to which the toner image is transferred is transported to the fixing device 9, and after being heated and pressed by the heated fixing belt 20 and the pressure roller 21, the toner image is fixed on the paper P. Then, the paper P to which the toner image is fixed is separated from the fixing belt 20, and after being transported by a transport roller pair provided on the downstream side of the fixing device 9, it is discharged toward a paper discharge tray provided outside the device.

[0061] Next, a more detailed structure of the fixing device 9 will be described.

[0062] like Figure 2 As shown in FIG. 1 , the fixing device 9 according to the present embodiment includes a fixing belt 20 as a rotating member or a fixing member, a pressure roller 21 as an opposing member or a pressure member that contacts with the outer peripheral surface of the fixing belt 20 and forms a nip N, and a heating unit 19 that heats the fixing belt 20. In addition, the heating unit 19 includes a planar heater 22 as a heating member, a heater support 23 as a holding member that holds the heater 22, and a support member 24 as a supporting member that supports the heater support 23.

[0063] The fixing belt 20 is composed of an annular belt component, for example, a cylindrical substrate made of polyimide (PI) with an outer diameter of 25 mm and a thickness of 40 to 120 μm. In order to improve durability and ensure demolding properties, a demolding layer with a thickness of 5 to 50 μm formed of a fluorine-based resin such as PFA or PTFE is formed on the outermost layer of the fixing belt 20. An elastic layer composed of rubber with a thickness of 50 to 500 μm may also be provided between the substrate and the demolding layer. In addition, the substrate of the fixing belt 20 is not limited to polyimide, but may also be a heat-resistant resin such as PEEK or a metal substrate such as nickel (Ni) or SUS. Polyimide or PTFE, etc. may also be coated on the inner circumferential surface of the fixing belt 20 as a sliding moving layer.

[0064] 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.

[0065] The fixing belt 20 is pressurized toward the pressure roller 21 by a pressure mechanism described later, and is pressed against the pressure roller 21. Thus, a clamping portion N is formed between the fixing belt 20 and the pressure roller 21. In addition, the pressure roller 21 functions as a driving roller that is rotationally driven after receiving a driving force from a driving mechanism provided in the main body of the image forming apparatus. On the other hand, the fixing belt 20 is configured to rotate with the rotation of the pressure roller 21. When the fixing belt 20 rotates, the fixing belt 20 slides relative to the heater 22. In order to improve the sliding mobility of the fixing belt 20, a lubricant such as oil or grease may be placed between the heater 22 and the fixing belt 20.

[0066] The heater 22 is provided in a strip shape in the rotation axis direction or the entire length direction of the fixing belt 20 (hereinafter also referred to as the "belt length direction"), and contacts the inner peripheral surface of the fixing belt 20 at a position corresponding to the pressure roller 21. The heater 22 is a member for heating the fixing belt 20 as a heated member and heating the fixing belt 20 to a predetermined fixing temperature.

[0067] Unlike the present embodiment, the heating unit 60 may be provided on the opposite side of the base material 50 to the fixing belt 20 side (heater support 23 side). In this case, since the heat of the heating unit 60 is transferred to the fixing belt 20 via the base material 50, the base material 50 is preferably made of a material with high thermal conductivity such as aluminum nitride. In addition, in the configuration of the heater 22 involved in the present embodiment, an insulating layer may be further provided on the surface of the base material 50 on the opposite side to the fixing belt 20 (heater support 23 side).

[0068] The fixing belt 20 may be in indirect contact with the heater 22 via a non-contact or low-friction sheet, but in order to improve the heat transfer efficiency to the fixing belt 20, it is preferred that the heater 22 is in direct contact with the fixing belt 20 as in the present embodiment. In addition, although the heater 22 may be in contact with the outer peripheral surface of the fixing belt 20, the fixing quality may be reduced if the outer peripheral surface of the fixing belt 20 is damaged by contact with the heater 22, so it is preferred that the surface in contact with the heater 22 is the inner peripheral surface of the fixing belt 20.

[0069] The heater support 23 and the support 24 are arranged inside 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 walls of the fixing device 9. The surface of the heater support 23 opposite to the heater 22 side is supported by the support 24, and the heater 22 and the heater support 23 are kept without large bending to the pressure of the pressure roller 21, and a nip N is formed between the fixing belt 20 and the pressure roller 21.

[0070] 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.

[0071] When the printing operation starts, the heating unit 60 generates heat by supplying power to the heater 22, and the fixing belt 20 is heated. In addition, the pressure roller 21 is driven to rotate, and the fixing belt 20 starts to rotate. Then, when the temperature of the fixing belt 20 reaches the predetermined target temperature (fixing temperature), the fixing belt 20 is turned off. Figure 2As shown, the paper P carrying the unfixed toner image is conveyed (refer to Figure 2 The unfixed toner image is heated and pressurized and fixed on the paper P.

[0072] Figure 3 The figure shows a three-dimensional view of the fixing device. Figure 4 Shown is its exploded perspective view.

[0073] like Figure 3 and Figure 4 As shown, the device frame 40 of the fixing device 9 includes a first device frame 25 composed of a pair of side wall members 28 and a front wall member 27, and a second device frame 26 composed of a rear wall member 29. The pair of side wall members 28 are arranged at one end side and the other end side in the belt length direction, and the fixing belt 20, the pressure roller 21 and the two end sides of the heating unit 19 are supported by the two side wall members 28. A plurality of engaging protrusions 28a are provided in each side wall member 28, and the first device frame 25 and the second device frame 26 are assembled by engaging each engaging protrusion 28a with an engaging hole 29a provided in the rear wall member 29.

[0074] In addition, each side wall member 28 is provided with an insertion groove 28b for inserting the rotating shaft of the pressure roller 21. The insertion groove 28b is open on one side of the rear wall member 29, and the opposite side is a non-opening abutment portion. A bearing 30 for supporting the rotating shaft of the pressure roller 21 is provided at an end of one side of the abutment portion. Both ends of the rotating shaft of the pressure roller 21 are respectively attached to the bearing 30, thereby being supported rotatably by the side wall members 28.

[0075] In addition, a drive transmission gear 31 as a drive transmission component is provided at one end side of the rotating shaft of the pressure roller 21. When the pressure roller 21 is supported by the two side wall components 28, the drive transmission gear 31 is configured to be exposed to the outside more than the side wall components 28. Therefore, when the fixing device 9 is installed in the main body of the image forming device, the drive transmission gear 31 is connected to the gear provided in the main body of the image forming device, and becomes a state capable of transmitting the driving force from the driving source. In addition, as a drive transmission component that transmits the driving force to the pressure roller 21, in addition to the drive transmission gear 31, it can also be a pulley, a coupling, etc. that tensions and stretches the drive transmission belt.

[0076] A pair of flanges 32 for supporting the fixing belt 20, the heater support 23, the support 24, etc. are provided at both ends in the longitudinal direction of the heating unit 19. A guide groove 32a is provided on each flange 32. The flange 32 is assembled to the side wall member 28 by inserting the guide groove 32a along the edge of the insertion groove 28b of the side wall member 28.

[0077] In addition, a pair of springs 33 as biasing members abut against each flange 32. Each spring 33 biases the support member 24 and the flange 32 toward the pressure roller 21, so that the fixing belt 20 is pressed against the pressure roller 21, and a nip portion is formed between the fixing belt 20 and the pressure roller 21. The end of the spring 33 on the opposite side to the side abutting against the flange 32 is pressed by a pressure lever described later.

[0078] In addition, if Figure 4 As shown, a hole portion 29b as a positioning portion is provided at one end side in the length direction of the rear wall member 29 constituting the second device frame 26 to position the fixing device body of the image forming device body. On the other hand, a protrusion 101 as a positioning portion is provided in the image forming device body. By inserting the protrusion 101 into the hole portion 29b of the fixing device 9 so that the protrusion 101 and the hole portion 29b are engaged, the fixing device body is positioned in the belt length direction relative to the image forming device body. In addition, no positioning portion is provided at the end side of the rear wall member 29 opposite to the end side where the hole portion 29b is provided. As a result, the expansion and contraction of the fixing device body in the belt length direction accompanying the temperature change is not restricted.

[0079] Figure 5 Shown is a perspective view of the heating unit 19, Figure 6 Shown is its exploded perspective view.

[0080] like Figure 5 and Figure 6 As shown, on the fixing belt side of the heater support member 23 ( Figure 5 and Figure 6 A rectangular receiving recess 23a for receiving the heater 22 is provided in the front side surface of the housing 23a. The receiving recess 23a is formed to have substantially the same shape and size as the heater 22, but the length dimension L2 of the receiving recess 23a is set to be slightly longer than the length dimension L1 of the heater 22. In this way, since the receiving recess 23a is formed to be slightly longer than the heater 22, even if the heater 22 is elongated in its length direction due to thermal expansion, the heater 22 and the receiving recess 23a will not interfere with each other. In addition, the heater 22 is sandwiched and held together with the heater support 23 by a connector described later as a power supply component while being received in the receiving recess 23a.

[0081] The pair of flanges 32 includes a C-shaped belt support member 32b inserted into the inner side of the fixing belt 20 to support the fixing belt 20, a flange-shaped belt restriction member 32c that contacts the end surface of the fixing belt 20 to restrict the movement (bias) in the belt length direction, and a support recess 32d inserted into both end sides of the heater support member 23 and the support member 24 to support them. By inserting the belt support member 32b into both end portions of the fixing belt 20, when the belt is not rotating, tension in the circumferential direction (belt rotation direction) is basically not generated, that is, the belt is supported in a so-called free belt manner.

[0082] like Figure 5 and Figure 6 As shown, a positioning recess 23e serving as a positioning portion is provided in one end side in the longitudinal direction of the heater support member 23. Figure 5 and Figure 6 The fitting portion 32e of the flange 32 shown on the left side of the figure is fitted into the positioning recess 23e to position the heater support 23 and the flange 32 in the belt length direction. Figure 5 and Figure 6 The flange 32 shown on the right side of the figure does not have the fitting portion 32e, and is not positioned in the belt length direction with the heater support 23. In this way, by positioning the heater support 23 with respect to the flange 32 only on one side in the belt length direction, even if the heater support 23 expands and contracts in the belt length direction due to temperature changes, its expansion and contraction is not restricted.

[0083] In addition, if Figure 6 As shown, step portions 24a are provided at both ends of the support member 24 in the long-side direction to limit the movement of the support member 24 relative to each flange 32. Each step portion 24a limits the movement of the support member 24 in the length direction relative to the flange 32 by abutting against the flange 32. However, at least one of these step portions 24a is arranged with a gap (looseness) relative to the flange 32. In this way, since at least one of the step portions 24a is arranged with a gap relative to the flange 32, even if the bracket 24 expands and contracts in the long-side direction of the belt due to temperature changes, its expansion and contraction will not be limited.

[0084] Figure 7 Shown is a top view of the heater 22. Figure 8 Shown is its exploded perspective view.

[0085] like Figure 8As shown, the heater 22 includes a base material 50, a first insulating layer 51 provided on the base material 50, a conductor layer 52 having a heating portion 60 and the like provided on the first insulating layer 51, and a second insulating layer 53 covering the conductor layer 52. In this embodiment, the base material 50, the first insulating layer 51, the conductor layer 52 (heating portion 60), and the second insulating layer 53 are stacked in this order toward the fixing belt 20 side (the clamping portion N side), and the heat generated from the heating portion 60 is transferred to the fixing belt 20 via the second insulating layer 53 (see Figure 2 ).

[0086] The base material 50 is a long strip of plate material made of metal materials such as stainless steel (SUS), iron, and aluminum. In addition, as the material of the base material 50, in addition to metal materials, ceramics, glass, etc. can also be used. In the case where an insulating material such as ceramic is used for the base material 50, the first insulating layer 51 between the base material 50 and the conductor layer 52 can be omitted. On the other hand, since metal materials have excellent durability against rapid heating and are easy to process, they are suitable for achieving low costs. Even among metal materials, aluminum and copper are particularly preferred because they have high thermal conductivity and are unlikely to cause temperature unevenness. In addition, stainless steel has the advantage of being cheaply manufactured compared to them.

[0087] Each of the insulating layers 51 and 53 is made of a material having insulating properties such as heat-resistant glass. Alternatively, ceramics or polyimide (PI) may be used as these materials.

[0088] The conductor layer 52 is composed of a heat generating component 60 having a plurality of impedance heating elements 59, a plurality of electrodes 61, and a plurality of power supply lines 62 as conductors electrically connecting them. Each impedance heating element 59 is electrically connected in parallel to any two of the three electrodes 61 via a plurality of power supply lines 62 provided on the base material 50.

[0089] The heating portion 60 is formed by, for example, applying a paste mixed with silver palladium (AgPd) or glass powder to the base material 50 by screen printing or the like, and then sintering the base material 50. As the material of the heating portion 60, in addition to these, a resistor material of silver alloy (AgPt) or ruthenium oxide (RuO2) can also be used.

[0090] The power supply line 62 is made of a conductor having a lower resistance than the heating element 60. The power supply line 62 and the electrode 61 can be made of silver (Ag) or silver palladium (AgPd) and can be formed by screen printing such a material.

[0091] Fig. 9 Shown is a perspective view of a state in which the connector 70 is connected to the heater 22 .

[0092] like Fig. 9 As shown, the connector 70 includes a housing 71 made of resin and a plurality of contact terminals 72 provided on the housing 71. Each contact terminal 72 is formed of a leaf spring and is connected to a harness 73 for power supply.

[0093] like Fig. 9 As shown, the connector 70 is installed in a manner that clamps the heater 22 and the heater support 23 from both the front side and the back side. In this state, the contact portion 72a provided at the front end of each contact terminal 72 is in elastic contact (crimped) with the corresponding electrode 61, and the heating portion 60 is electrically connected to the power supply provided in the image forming device by means of the connector 70. As a result, it is possible to supply power from the power supply to the heating portion 60. In addition, in order to ensure the connection with the connector 70, at least a portion of each electrode 61 is not covered by the second insulating layer 53 and is exposed (refer to Figure 7 ).

[0094] like Fig.10 As shown, in the present embodiment, among the plurality of impedance heating elements 59 arranged in the longitudinal direction of the base material 50, the first heating portion (first impedance heating element group) 60A constituted by the impedance heating elements 59 other than the two ends, and the second heating portion (second impedance heating element group) 60B constituted by the impedance heating elements 59 at the two ends can be independently controlled to perform heating. Specifically, the impedance heating elements 59 other than the two ends constituting the first heating portion 60A are connected to the first electrode 61A provided at one end in the longitudinal direction of the base material 50 via the first power supply line 62A. In addition, the impedance heating elements 59 constituting the first heating portion 60A are connected to the second electrode 61B provided at the opposite end side of the first electrode 61A via the second power supply line 62B. On the other hand, the impedance heating elements 59 at the two ends constituting the second heating portion 60B are connected to the third electrode 61C (other than the first electrode 61A) provided at one end in the longitudinal direction of the base material 50 via the third power supply line 62C or the fourth power supply line 62D. In addition, the resistance heating elements 59 at both ends are connected to the second electrode 61B via the second power supply line 62 similarly to the resistance heating elements 59 of the first heat generating portion 60A.

[0095] In addition, each electrode 61A to 61C is connected to the power supply 64 via the above-mentioned connector 70, and power is supplied from the power supply 64. A switch 65A as a switching component is provided between the electrode 61A and the power supply 64, and the application of voltage can be switched by turning the switch 65A on and off. Similarly, a switch 65C as a switching component is provided between the electrode 61C and the power supply 64, and the application of voltage can be switched by turning the switch 65C on and off. Furthermore, the timing of turning on and off these switches 65A and 65C and supplying power to the heater 22 is controlled by the control circuit 66. In addition, the control circuit 66 performs these controls based on the detection results of various sensors in the image forming device. For example, the timing of the paper passing through the paper can be determined based on the detection results of the sensor provided at the entrance or exit of the fixing nip N, and whether to supply power to the heater 22 and the switches 65A and 65C can be switched.

[0096] When voltage is applied to the first electrode 61A and the second electrode 61B, only the first heating portion 60A generates heat by energizing each of the impedance heating elements 59 other than the two ends. On the other hand, when voltage is applied to the second electrode 61B and the third electrode 61C, only the second heating portion 60B generates heat by energizing each of the impedance heating elements 59 at the two ends. In addition, if voltage is applied to all of the electrodes 61A to 61C, (all) the impedance heating elements 59 of both the first heating portion 60A and the second heating portion 60B can be heated. For example, when a relatively small width size of paper less than A4 size (passing paper width: 210 mm) is passed through, only the first heating portion 60A is heated, and when a relatively large width size exceeding A4 size (passing paper width: 210 mm) is passed through, by also causing the second heating portion 60B to heat in addition to the first heating portion 60A, a heating area corresponding to the width of the paper can be formed.

[0097] However, in order to further miniaturize the image forming apparatus and the fixing device, miniaturization of the heater, which is one of the components arranged inside the fixing belt, is important. Fig.10 The arrow Y direction in FIG. 1 is a direction intersecting the length direction along the surface of the heating portion 60A, 60B provided with the heater 22, or a direction orthogonal to the length direction of the heater 22 and different from the length direction of the heater 22. Fig.10 The fixing belt can be made smaller in diameter, thereby miniaturizing the fixing device and the image forming device. Specifically, as a method of reducing the heater in the short side direction, for example, the following three methods can be cited.

[0098] One method is to reduce the length of the short side direction of the heating part (resistance heating element). However, when the short side direction of the heating part is reduced, since the width of the heated area where the fixing belt is heated becomes smaller, when it is necessary to ensure the heat applied to the fixing belt, there will be a problem of a higher temperature rise peak. When the temperature rise peak increases, the temperature of the over-temperature detection device such as the thermostat and fuse provided on the back of the heater may exceed the heat-resistant temperature, or the over-temperature detection device may malfunction. In addition, when the temperature rise peak becomes higher, since the heat transfer efficiency from the heater to the fixing belt is also reduced, it is not preferred from the viewpoint of energy efficiency. In this way, there is a situation where it is difficult to adopt the method of making the heating part smaller in the short side direction.

[0099] As a second method, the length in the short side direction of the portion where the heating part, electrode, and power supply line are not provided is reduced. However, in this method, since the interval between the heating part and the power supply line, and between the electrode and the power supply line becomes smaller, it may not be possible to ensure insulation. In view of the structure of the existing heater, it is difficult to further reduce the interval between the heating part and the power supply line, and between the electrode and the power supply line.

[0100] As the remaining third method, there is a method of making the power supply line smaller in the short side direction. Compared with the above two methods, this method has room for implementation. However, when the length of the power supply line in the short side direction is reduced, the resistance value of the power supply line increases, so it is possible to produce unexpected shunts on the conductive path of the heater. In particular, when the heat generated by the heating part is increased to cope with the high speed of the image forming device and the resistance value of the heating part is reduced, unexpected shunts are likely to occur because the resistance value of the power supply line and the resistance value of the heating part are relatively close. As a method to avoid such unexpected shunts, it is considered to increase the thickness direction (the direction intersecting the length direction and the short side direction) accordingly by the amount that the power supply line is reduced in the short side direction, thereby ensuring the cross-sectional area and suppressing the increase in the resistance value of the power supply line. However, in this case, it becomes difficult to screen-print the power supply line, and the method of forming the power supply line will be forced to change. Therefore, it is difficult to adopt a solution of thickening the power supply line. Therefore, in order to achieve miniaturization of the heater in the short-side direction, it is necessary to reduce the length of the power supply line in the short-side direction in anticipation of an increase in resistance value, and to take separate measures to cope with unexpected current diversion that may occur as a result.

[0101] Next, the unexpected flow diversion and the adverse effects caused thereby will be described by taking the heater 22 as an example.

[0102] exist Fig.11In the heater 22 shown, when a voltage is applied to the first electrode 61A and the second electrode 61B in order to generate heat only for each impedance heating element 59 of the first heating portion 60A, current usually flows through the first power supply line 62A and flows to the second power supply line 62B through each impedance heating element 59 other than the two ends.

[0103] However, due to the increase in the resistance value of the power supply line accompanying the miniaturization and the decrease in the resistance value of the heating part accompanying the increase in the heat generation, the difference in the resistance value between the power supply line and the heating part becomes smaller, as shown in FIG. Fig.12 As shown, unexpected paths may occur. Fig.12 A portion of the current of the second left impedance heating element 59 flows toward the opposite side of the second electrode 61B at the branch portion X of the second power supply line 62A in front. Then, the divided current flows through Fig.12 The electric current flows through the impedance heating element 59 at the left end of the circuit, and further passes through the third power supply line 62C, the third electrode 61C, the fourth power supply line 62D, and the impedance heating element 59 at the right end in sequence, and then merges with the second power supply line 62B.

[0104] So, in Fig.12 The heater 22 shown includes a portion of the second power supply line 62B extending from the branch portion X to the left side of the figure, each impedance heating element 59 constituting the two ends of the second heating portion 60B, a third electrode 61C, a third power supply line 62C and a portion of the fourth power supply line 62D, forming a branch conductive path E3 through which current flows in an unexpected path.

[0105] In addition, if the conductive path of the heater 22 has at least a first conductive portion E1 connecting the first heating portion 60A and the first electrode 61A, a first conductive portion E2 extending from the first heating portion 60A to the heater 22 in a first direction S1 ( Fig.12 The second conductive portion E2 extending from the second conductive portion E2 to the right side of the first electrode 61B and connected to the second electrode 61B, and the second conductive portion E2 extending from the second conductive portion E2 in a second direction S2 ( Fig.12 In the case where a branched conductive path E3 is formed (on the left side of the figure) and then branches out without passing through the first conductive part E1 but is connected to the second conductive part E2 or the second electrode 61B, such unexpected shunt may occur when the first heating part 60A is energized. In this embodiment, although the second heating part 60B and the third electrode 61C are provided on the branched conductive path E3, there is a possibility of unexpected shunt in a conductive path without the second heating part 60B and the third electrode 61C, or even in a conductive path with conductive components other than these.

[0106] Then, when unexpected current diversion occurs, since the current flows through an unexpected path, the temperature distribution of the heater 22 may be uneven due to the heat generated by the power supply line. Fig.13 In the heater 22 shown, 20% of the current flows evenly through each impedance heating element 59 from the first electrode 61A to the first heating portion 60A, and when the current passing through the second impedance heating element 59 from the left in the figure is diverted by 5% at the branch portion X in front of it, the heat generated by the power supply line in each block divided by each impedance heating element 59 is as shown in the table in the figure.

[0107] Here, since the portion of each power supply line extending in the short-side direction of the heater 22 is short, the heat generated in this portion is small, so this heat generated is ignored, and only the heat generated by the portion of each power supply line extending in the long-side direction of the heater 22 is calculated. Specifically, the heat generated by the portion of the first power supply line 62A, the second power supply line 62B, and the fourth power supply line 62D extending in the longitudinal direction of each heater 22 is calculated. In addition, since the heat value (W) is expressed by the following formula (1), Fig.13 For convenience, the calorific value shown in the table is calculated as the square of the current (I) flowing through each power supply line. Therefore, Fig.13 The calorific value values ​​shown in the table are simply calculated values ​​and are different from the actual calorific value.

[0108] W (heat generation) = R (resistance) × I 2 (Current)···(1)

[0109] according to Fig.13 To specifically describe the method of calculating the amount of heat, in the first block, since the current flowing through the first power supply line 62A is 100%, and the current flowing through the fourth power supply line 62D is 5%, the sum of the squares of the respective values, 10025 (10000+25), becomes the total amount of heat generated by the power supply lines in the first block. In addition, in the second block, since the current flowing through the first power supply line 62A is 80%, the current flowing through the second power supply line 62B is 5%, and the current flowing through the fourth power supply line 62D is 5%, the sum of the squares of the respective values, 6450 (6400+25+25), becomes the total amount of heat generated by the power supply lines in the second block. In addition, the heat generated is calculated in the same manner in the other blocks.

[0110] Then, Fig.14 Shown is Fig.13 The total heat generation of each block is shown in the table. Fig.14 As shown, the total heat generation of each block is asymmetric left and right based on the fourth block in the center of the heat generation area due to the influence of the unexpected flow diversion mentioned above.

[0111] In addition, even when all the heating parts are energized, the heating value in the longitudinal direction of the heater 22 will be asymmetrical due to the difference in the magnitude of the current flowing through the conductive part. That is, as described above, when the heater 22 is miniaturized, the configuration of the electrodes and the conductive part is also restricted, so it is difficult to make the heating value in the longitudinal direction of the heater 22 symmetrical. In addition, as described above, when trying to achieve high speed of the device, the current value flowing in the conductive part becomes larger, and the difference between the left and right becomes larger, so the difference cannot be ignored. The following is a description of the case where all the heating parts are energized.

[0112] like Fig.15 As shown in FIG. 1 , when all the heating parts are energized, 20% of the current also flows through the resistance heating element 59 at the left and right ends and the power supply lines 62C and 62D connected thereto, which is different from the above case. In contrast, the value of the current flowing to the power supply line 62A is the same as before. At this time, in the first block, since the current flowing through the first power supply line 62A is 100%, and the current flowing through the fourth power supply line 62D is 20%, the total value of the square of each is 10400 (10000+400) which becomes the total calorific value of the power supply lines in the first block. In addition, in the second block, since the current flowing through the first power supply line 62A is 80%, the current flowing through the second power supply line 62B is 20%, and the current flowing through the fourth power supply line 62D is 20%, the total value of the square of these is 7200 (6400+400+400) which becomes the total calorific value of the power supply lines in the second block. In addition, the calorific value is calculated in the same way in the other blocks.

[0113] Then, if Fig.16 As shown, the total heat generation of each block is asymmetric with respect to the fourth block in the center of the heating area. In particular, the current value in the seventh block, which is the downstream side of the second power supply line 62B connected to all the impedance heating elements 59, increases to 120%, resulting in a difference in heat generation on the left and right.

[0114] The uneven heat generation of the asymmetric power supply lines causes uneven temperature in the longitudinal direction of the heater 22. When the temperature of the heater 22 is uneven in the longitudinal direction, the image fixed on the paper has high gloss in the high temperature portion and low gloss in the low temperature portion, so the overall gloss may be uneven, which may lead to a decrease in image quality. In addition, in this embodiment, in order to evenly heat small-sized paper and large-sized paper, the lengths of the blocks are set to be the same.

[0115] Therefore, in this embodiment, for the above-mentioned case of partial energization (when passing through small-sized paper) and the case of energizing all heating parts (when passing through large-sized paper), in order to suppress the adverse conditions (for example, uneven gloss or uneven image gloss) caused by uneven temperature in the longitudinal direction of the heater 22, the countermeasures described below are taken.

[0116] like Fig.17 As shown, the flanges 321 and 322 that respectively support the end portions on one side and the other side in the longitudinal direction of the fixing belt 20 are pressed by independent pressing mechanisms, and the fixing belt 20 is pressed against the pressing roller 21 by the pressing to form a nip N.

[0117] When there is no need to change the pressure conditions (details will be described later), the pressure F applied to the flange 321 L and the pressure F applied to the flange 322 R are set to be the same (hereinafter, the setting of the pressurizing force is referred to as the isopressurizing condition).

[0118] Fig.18 The figure shows the longitudinal positional relationship between the heater 22 and other components in the fixing device 9. The upper side of the figure shows the heater 22, and the middle shows the components in the fixing device 9, and the longitudinal positional relationship thereof is shown. In addition, the lower side of the figure shows the distribution of the temperature (temperature T) of the fixing belt 20 at each longitudinal position. Fig.18 The paper P passing through the heater 22 is a small-size paper corresponding to the heater 22, for example, an A4-size paper.

[0119] like Fig.18 As shown in the upper side of the figure, corresponding to the small size of paper, only the first heating part 60A in the heater 22 is energized. At this time, as described above, the heat generated by the heater 22 becomes larger on one side (the left side of the figure) in the longitudinal direction, as shown in the figure. Fig.18 As shown in the lower side of the figure, the temperature T of the fixing belt 20 also increases on the left side of the figure. Here, "the heat generation on one side of the length direction of the heater 22 is large" means that the heat generation when measured with a single heater 22 is large.

[0120] In this embodiment, the pressure applied by the pressure mechanism to each flange 321, 322 can be changed from the above-mentioned pressure conditions, and the pressure can be changed according to the distribution of the temperature T of the fixing belt 20 (or the distribution of the heat generated by the heater 22). Fig.18 As shown in the middle of FIG. 1 , the pressure applied to the flange 321 supporting the end portion of the fixing belt 20 in the longitudinal direction is changed to a specific pressure F. L Small pressure F L1 , and the pressure on the flange 322 on the other side is set to the pressure F Runchanged (hereinafter, the setting of the pressure is referred to as the first pressure condition). That is, the pressure applied to the flange 321 is set to be smaller than the pressure applied to the flange 322. As a result, the clamping pressure of the clamping portion N on the side where the heat generated in the longitudinal direction of the heater 22 is large (the pressing force of the fixing belt 20 and the pressure roller 21 at the clamping portion) becomes relatively small. Furthermore, the width of the clamping portion N in the direction orthogonal to the longitudinal direction of the heater 22 (also the conveying direction of the paper P at the clamping portion) (hereinafter, the clamping portion width) becomes relatively small on the side where the heat generated in the longitudinal direction of the heater 22 is large. Therefore, it is possible to suppress the adverse conditions caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 24. That is, it is possible to suppress the difference in fixability between one side and the other side in the longitudinal direction, and to suppress the gloss deviation in the longitudinal direction. Therefore, it is possible to suppress the image unevenness and gloss unevenness of the paper.

[0121] In addition, if Fig.19 As shown in FIG. 1 , when a large-size paper (e.g., A3-size paper) is passed, that is, when all the heating parts are energized, the temperature T (heat generated by the heater 22) on the other side in the longitudinal direction is higher than that on one side. At this time, the pressure applied to the flange 321 is set to the pressure F without changing from the equal pressure condition. L , and the pressure on the flange 322 is changed to a specific pressure F R Small pressure F R1 (Hereinafter, the setting of the pressure is referred to as the second pressure condition.) That is, the pressure applied to the flange 322 is set to be smaller than the pressure applied to the flange 321. As a result, the clamping pressure on the side of the heater 22 with a larger heat generation in the longitudinal direction becomes relatively small. Furthermore, the clamping width on the side of the heater 22 with a larger heat generation in the longitudinal direction becomes relatively small. Therefore, it is possible to suppress the adverse conditions caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 24. That is, it is possible to suppress the difference in fixability between one side and the other side in the longitudinal direction, and to suppress the gloss deviation in the longitudinal direction.

[0122] The pressing force and the clamping pressure can be calculated by measuring the surface pressure using a pressure distribution measurement system and dividing the pressure in the pressurized area by the area. Specifically, a surface pressure distribution measurement system (manufactured by Neptune: I-SCAN) or the like can be used.

[0123] The method for measuring the width of the clamping portion is to force the fixing device to stop for 10 seconds while a solid black image previously produced by other image forming devices is passing through a sheet of paper in a fixing device. Then, a glossy portion of the width of the clamping portion can be formed on the solid black image from which the solid black image is extracted.

[0124] By measuring the width of the glossy portion, the nip width can be known. Alternatively, the nip width can be determined by passing the OHP paper through the nip, pulling out the OHP paper after the contact state lasts for a certain period of time, and measuring the width of the nip trace formed to determine the nip width.

[0125] Next, through Fig. 20 A specific example of the switching timing of each pressurizing condition described above will be described.

[0126] like Fig. 20 As shown, first, when the power is turned on in the image forming apparatus 1 (step S0), power is supplied to the fixing device. At this time, the pressure mechanism is operated, and the fixing belt 20 is pressed against the pressure roller 21 under constant pressure conditions (step S1).

[0127] When the image forming device 1 receives the printing instruction (step S2), the image forming device 1 recognizes the size of the paper to be printed and starts the printing operation (image forming operation) (step S3). The printing operation (image forming operation) mentioned here means, as described above, from the time when the printing instruction reaches the image forming device and various operations for printing are started (heating of the fixing belt to the fixing temperature, or rotation of various rollers for conveying paper, etc.), until the printing of the last paper is completed and the paper is ejected outside the device, and various operations for printing are completed.

[0128] When the printing operation starts, the fixing belt 20 is heated to the target temperature and maintained at the temperature by the heater 22, so that the fixing operation can be performed. After the printing operation starts, the pressurization condition of the pressurization mechanism for pressurizing the fixing belt 20 is changed according to the size of the paper to be printed (step S4). Specifically, as described above, the first pressurization condition is set in the case of small-sized paper, and the second pressurization condition is set in the case of large-sized paper (steps S5A, 5B). In addition, in the present embodiment, one of the first pressurization condition or the second pressurization condition is set, and it can also be set to the case where the equal pressurization condition is set according to the printing conditions such as the size of the paper. In addition, as the timing for changing the pressurization condition after the start of the above-mentioned printing operation, it can be set to a timing such as a specified timing after the printing operation starts or until the first paper enters the fixing device.

[0129] Then, the pressurizing mechanism passes the paper through the fixing device under the pressurizing conditions set in steps S5A and 5B. Then, when the fixing operation for all the paper is completed and the printing operation is completed (step S6), the pressurizing mechanism is changed to the equal pressurizing conditions (step S7).

[0130] As described above, by changing the pressing condition according to the size of the paper passing through, the fixing performance of the paper during the fixing operation can be aligned on one side and the other side in the length direction of the fixing belt, and the gloss unevenness or gloss unevenness of the image formed on the paper can be suppressed. In addition, by setting the pressing condition to be equal except when the printing operation is executed, the time caused by the left-right deviation of the pressing force can be extremely reduced, and the left-right deviation of the wear of the fixing belt 20 and the pressing roller 21 can be suppressed.

[0131] Next, examples in which the switching timing of the pressurization conditions different from the above are set will be described in order.

[0132] exist Fig.21 In the embodiment of the flowchart shown, after the printing operation starts (step S3), the pressurization conditions are not changed and are set to equal pressurization conditions (steps S11A, 11B) until B sheets of paper have passed through the fixing device. In addition, when B sheets of paper have passed through the fixing device refers to the moment when the sensor provided on the exit side of the fixing clamping portion N detects the rear end of the Bth sheet of paper. Then, after B sheets of paper have passed, the pressurization conditions are changed according to the paper size (steps S5A, 5B). After that, the steps of changing to equal pressurization conditions again after the printing operation is completed are the same. In addition, Fig.21 The figure shows the case where the number of sheets to be printed is B or more. If the number of sheets is less than B, the printing operation is terminated without changing the equal pressure conditions.

[0133] Immediately after the printing operation starts, the temperature deviation of the heater 22 and the fixing belt 20 is small. Therefore, as in the present embodiment, by setting the pressing condition to the constant pressing condition until B sheets pass, the pressing can be performed in a time period when the gloss unevenness of the image or the gloss unevenness is not likely to occur. Therefore, compared with the case where the pressing condition is changed immediately after the printing operation starts, the time for the pressing deviation to occur can be further reduced, and the left-right deviation of the wear of the fixing belt 20 and the pressing roller 21 can be further suppressed.

[0134] In the above embodiment, the pressure condition is changed after the Bth sheet of paper passes through the fixing device, but the present invention is not limited to this. By providing a sensor at a position corresponding to the Bth sheet of paper discharged to the outside of the machine or passing through the entrance side of the fixing device, these timings can be selected. In addition, the pressure condition can be changed according to the paper size after a predetermined C time has passed after the start of the printing operation. Even in this case, the time zone in which the gloss of the image is uneven or the fixing unevenness is not easy to occur is set as the equal pressure condition, which can further suppress the left-right deviation of the wear of the fixing belt 20 and the pressure roller 21. In addition, the C time is not limited to the time from the start of the printing operation, and the timing can be selected from the time when the first paper passes through the predetermined registration roller or from the time when it reaches the fixing device. In addition, the B sheets or C time can be selected according to the productivity of the image forming device, the heat capacity of the fixing belt, the linear speed of the paper, or the thickness of the paper, etc. The optimal value can be selected, for example, B = 2 sheets and C = 10 seconds.

[0135] Next, a case where the pressure increase condition is changed according to the temperature detected by the temperature detection means will be described.

[0136] like Fig. 22 As shown in the figure, in the present embodiment, temperature detection mechanisms 41a and 41b for detecting the surface temperature of the fixing belt 20 are respectively provided on one side and the other side of the length direction of the fixing belt 20 (also a direction orthogonal to the length direction of the heater 22 and the conveying direction of the paper) so as to face the fixing belt 20. As the temperature detection mechanisms 41a and 41b, for example, thermistors can be used, and other known temperature detection mechanisms can also be used as appropriate.

[0137] In this embodiment, the temperature detection mechanisms 41a and 41b are respectively arranged in the longitudinal direction of the heater 22 at positions corresponding to one end and the other end in the longitudinal direction of the small-sized paper P passing through the fixing clamping portion. In other words, they are respectively arranged in positions corresponding to the second block and the sixth block.

[0138] The presence or absence of a change in the pressurization condition is determined by whether the difference between the temperature Tb detected by the temperature detection mechanism 41a, 41b and the temperature Ta exceeds the set threshold temperature difference T1. In this embodiment, the temperature detection results of the temperature detection mechanism 41a, 41b are used to determine the pressurization condition when passing small-size paper.

[0139] Specifically, if Fig.23As shown, when a printing instruction is issued and the printing operation of small-size paper is started (steps S2 and S3), the temperature detection mechanisms 41a and 41b detect the temperatures Ta and Tb at predetermined intervals. Then, when the temperature Ta is higher than the temperature Tb by more than the temperature T1 (step S41), the pressure mechanism is changed to the first pressure condition, and the pressure on one side in the length direction is reduced. That is, the pressure on the side with the higher temperature detected by the temperature detection mechanisms 41a and 41b is reduced. After that, the steps of changing to equal pressure conditions again after the printing operation is completed are the same. In addition, when the temperature difference does not exceed T1 during the printing operation, the printing operation is directly terminated (step S43).

[0140] In addition, a temperature detection mechanism may be provided at a position corresponding to the widthwise end of the large-size paper. Fig.24 As shown in FIG. 1 , the temperature detection mechanisms 41a and 41b are respectively arranged at positions corresponding to one end and the other end in the length direction of the large-sized paper P, in other words, at positions corresponding to the first block and the seventh block, respectively. In this embodiment, the temperature detection results of the temperature detection mechanisms 41a and 41b are used to determine the pressurization conditions when the large-sized paper passes.

[0141] Specifically, if Fig.25 As shown in FIG. 1 , when the printing operation of the large-size paper starts (steps S2 and S3), the temperature detection mechanisms 41a and 41b detect the temperatures Ta and Tb at predetermined intervals. Then, when the temperature Tb is higher than the temperature Ta by more than the temperature T2 (step S42), the pressurizing mechanism is changed to the second pressurizing condition, and the pressurizing force at the other end in the longitudinal direction is reduced. That is, the pressurizing force at the side with the higher temperature detected by the temperature detection mechanisms 41a and 41b is reduced.

[0142] As described above, by detecting the temperature of the fixing belt 20 through the temperature detection mechanisms 41a and 41b, the pressure conditions can be changed at a more appropriate timing, and the inconvenience caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 24 can be suppressed. That is, the gloss unevenness of the image or the gloss unevenness can be effectively suppressed. Furthermore, the time for the pressure deviation to occur can be further reduced, so that the left-right deviation of the wear of the fixing belt 20 and the pressure roller 21 can be further suppressed.

[0143] In order to effectively prevent uneven gloss and uneven fixability of the image, it is preferred to set the temperatures T1 and T2 to less than 20 degrees. In addition, it is necessary to set the temperatures T1 and T2 in consideration of the temperature detection error and configuration error of the temperature detection mechanisms 41a and 41b, the deviation of the paper conveying position relative to the fixing nip, and the configuration error of each resistance heating element 59. That is, in order to suppress erroneous detection caused by these factors, it is more preferred to set the temperatures T1 and T2 to about 10 degrees.

[0144] As described above, the pressing condition can be changed at different times for various situations of large-size paper and small-size paper. In one image forming apparatus, the conditions for changing to the first pressing condition and the conditions for changing to the second pressing condition can be the same or different. For example, in the case of small-size paper, the first pressing condition is changed immediately after the printing operation starts, but in the case of large-size paper, the pressing condition can be changed after B sheets of paper pass through, and it can be appropriately selected according to the generation method of each temperature deviation. In addition, the pressing condition can be changed only for a certain size of paper.

[0145] In addition, as a timing different from the above timing, the fixing device may be used only when the paper P passes through the fixing device (the paper P passes through the fixing device). Figure 2 Thus, the effect of preventing uneven gloss or uneven fixability of the image will not be greatly impaired, and the time for pressure deviation to occur can be further reduced.

[0146] In addition, in the above embodiment, compared with the case of equal pressurization conditions, the pressure is reduced on the flange of the fixing belt 20 on the side where the heater 22 generates a large amount of heat in the longitudinal direction, but conversely, it is also possible to have a structure in which the pressure is increased on the side where the heater 22 generates a small amount of heat in the longitudinal direction.

[0147] Furthermore, in the above embodiment, the timing for returning the pressing condition to the equal pressing condition is after the printing operation is completed, but it may also be after the last paper is ejected from the image forming apparatus main body (just after being ejected to the image forming apparatus main body). Figure 1 or immediately after the last sheet of paper P passes through the fixing device (the rear end of the sheet of paper P passes through the fixing device). Figure 2 Thus, the effect of preventing uneven gloss or uneven fixability of the image will not be greatly impaired, and the time for pressure deviation to occur can be further reduced.

[0148] Next, a pressurizing mechanism for pressurizing the flanges 321 and 322 and changing the pressurizing force will be described.

[0149] 26(a), the fixing device 9 has a pressing mechanism 80A for pressing the flange 321 provided on one side in the longitudinal direction of the fixing belt 20. The pressing mechanism 80A has a spring 33 as a biasing member, a pressing rod 81 as a pressing mechanism, a cam 82 as a pressing force adjusting mechanism, and the like.

[0150] One end of the spring 33 is connected to the flange 321 , and the other end is connected to the pressure rod 81 .

[0151] The pressure rod 81 has a fulcrum 81a at one end in the longitudinal direction. The fulcrum 81a is fixed to a frame portion (eg, Figure 3 The pressure rod 81 is arranged to be rotatable around a fulcrum 81a (see Fig.26a The other end of the pressure rod 81 in the longitudinal direction abuts against the cam 82, and the other end of the pressure rod 81 abuts against the cam 82 ( Fig.26a The surface on the opposite side of the right side) is connected to the spring 33.

[0152] The cam 82 is provided so as to be rotatable about a cam shaft 82 a . The cam shaft 82 a is connected to a drive control mechanism 83 .

[0153] The drive control mechanism 83 includes a motor 84 that applies a rotational driving force to the cam shaft 82 a , and a control unit 85 that controls the motor.

[0154] One end side of the pressing lever 81 is pressed by the cam 82 , whereby the pressing force is transmitted to the flange 321 via the spring 33 , and the fixing belt 20 is pressed toward the pressing roller 21 side.

[0155] As shown in Figure 26(b), similar to the pressure mechanism 80A of the pressure flange 321, a pressure mechanism 80B of the pressure flange 322 is provided on the other end side in the longitudinal direction of the fixing belt 20. The pressure mechanism 80B has a structure basically the same as the pressure mechanism 80A. The respective cams 82 provided in the pressure mechanisms 80A and 80B have a common camshaft 82a, and only rotate in the same phase after being applied with a driving force by a common drive control mechanism 83. In this embodiment, the phases of the two cams 82, 82 are offset by 120 degrees. The drive control mechanism that rotates the camshaft 82a is composed of a pulse motor drive mechanism that is driven at intervals of 120 degrees. In addition, each pressure rod 81 is configured to be able to rotate independently around the fulcrum 81a.

[0156] The flange 321 is pressed by the pressing mechanism 80A, and the flange 322 is pressed by the pressing mechanism 80B, so that the fixing belt 20 is pressed against the pressing roller 21, and the fixing nip N is formed.

[0157] The pressing force of the flanges 321 and 322 is changed by rotating the cam shaft 82a by the drive control mechanism 83. That is, the surface of each cam 82 that contacts the pressing rod 81 is changed by the rotation of the cam shaft 82a as the center, thereby changing the pressing force.

[0158] Under the equal pressure condition, as shown in FIG. 26( a) and FIG. 26( b), the cams 82 of the pressurizing mechanisms 80A and 80B are oriented with their long diameter side (radius R1 side) toward the pressurizing rod 81, and the respective pressurizing forces are set to the same pressurizing force, i.e., the pressurizing force F L 、F R The cam 82 of the pressurizing mechanism 80A and the cam 82 of the pressurizing mechanism 80B have different rotation phases, and the short-diameter side contacts the pressurizing rod 81 at different timings. In addition, FIG. 26(a) and FIG. 26(b) are views viewed from the same direction.

[0159] As shown in FIG. 27( a) and FIG. 27( b), by rotating the cam shaft 82a by a predetermined rotation amount (in this embodiment, from Fig.26a The phase is rotated 120 degrees clockwise) to change to the first pressurizing condition. Specifically, the cam 82 of the pressurizing mechanism 80A makes the short diameter side (radius R2 side) abut against the pressurizing rod 81, and the cam 82 of the pressurizing mechanism 81B makes the long diameter side abut against the pressurizing rod 81. By changing the surface where the cam 82 of the pressurizing mechanism 80A abuts against the pressurizing rod 81 from the long diameter side to the short diameter side, the pressurizing force of the cam 82 on the pressurizing rod 81 becomes smaller, and accordingly, the spring load of the spring 33 on the flange 321 also becomes smaller. In other words, the force applying pressure to the flange 321 becomes smaller. On the other hand, the pressurizing force on the pressurizing mechanism 80B side does not change. As a result, each pressurizing force is set to the pressurizing force F L1 、F R In addition, Figure 26(a) to Figure 27(a) In the figure, the expansion and contraction amount of the spring 33 changes in accordance with the displacement of the pressurizing rod 81 in the left-right direction.

[0160] 28 (a) and FIG. 28 (b), by rotating the cam shaft 82a different from the predetermined rotation amount when the first pressurizing condition is changed (in this embodiment, from Fig.26a Specifically, the cam 82 of the pressurizing mechanism 80A makes the long diameter side contact with the pressurizing rod 81, and the cam 82 of the pressurizing mechanism 81B makes the short diameter side contact with the pressurizing rod 81, so that each pressurizing force is set to the pressurizing force F. L 、F R1 .

[0161] In this way, by staggering the phases of the cams 82, 82 of the pressurizing mechanisms 80A, 80B, the cams 82, 82 can be rotated by the common cam shaft 82a and the respective pressurizing conditions can be changed, thereby reducing the driving force of the pressurizing mechanisms 80A, 80B while preventing the rotational phase of the cams 82, 82 from being offset.

[0162] In the above description, a pressurizing mechanism is shown as a structure that reduces the pressurizing force on the side with a larger amount of heat in the longitudinal direction, but a pressurizing mechanism may also be a structure that increases the pressurizing force on the side with a smaller amount of heat. That is, a structure may also be a structure that increases the pressurizing force of the pressurizing mechanism 80B under the first pressurizing condition and increases the pressurizing force of the pressurizing mechanism 80A under the second pressurizing condition.

[0163] As an example, the pressurizing mechanism 80A and the pressurizing mechanism 80B shown in Figures 29(a) and 29(b) can be used. Different from the above-mentioned pressurizing mechanism, the range of the cam 82 on the short diameter side (radius R2 side) is larger, and the range on the long diameter side (radius R1 side) is smaller. The pressurizing mechanism 80A and the pressurizing mechanism 80B are the same in that they are 120 degrees out of phase with each other. Figures 29(a) and 29(b) show the case of equal pressurizing conditions. By rotating 120 degrees clockwise from the state in the figure, the cam 82 of the pressurizing mechanism 80B makes the long diameter side contact with the pressurizing rod 81, and the pressurizing force F of the pressurizing mechanism 80B is changed. R The pressure F of the pressure mechanism 80A L In addition, by rotating 240 degrees clockwise from the state in the figure, the cam 82 of the pressurizing mechanism 80A makes the long diameter side contact with the pressurizing rod 81, and changes to the pressurizing force F of the pressurizing mechanism 80A. L The pressure F of the pressure mechanism 80B R big conditions.

[0164] In the above embodiment, only the pressing force of the pressing mechanisms 80A and 80B is changed. However, the pressing force of the pressing mechanisms 80A and 80B may be changed to change the amount of pressure of the fixing belt 20 on the pressing roller 21 and change the width of the fixing nip.

[0165] For example, Fig.30 As shown, in the pressurizing mechanism 80A of the present embodiment, a pressurizing portion 81b is provided on the pressurizing rod 81 in place of the spring 33, and the pressurizing portion 81b protrudes toward the flange 321 and contacts the flange 321. The pressurizing mechanism 80B also has a basically similar structure.

[0166] In the structure using the above-mentioned spring 33, even if the position of the pressure rod 81 changes, the change is absorbed by the change in the compression amount of the spring 33. In contrast, in the present embodiment, the flange 321 moves by an amount corresponding to the movement of the pressure rod 81 in the left-right direction of the figure, and the pressure state of the fixing belt 20 on the pressure roller 21 changes. That is, the width of the fixing nip N changes.

[0167] In addition, Fig.30 The example of the cam 82 having a narrower range on the short diameter side is illustrated, but as shown in FIG. 29 , a cam 82 having a narrower range on the long diameter side may also be used, and the width of the fixing nip N on the side with smaller heat generation in the longitudinal direction may be increased.

[0168] As described above, in the present invention, by relatively reducing the pressing force of the pressing mechanism on the side where the heat generated in the longitudinal direction of the heater 22 is large, it is possible to suppress the inconvenience caused by the temperature deviation in the longitudinal direction of the heater 22 or the fixing belt 20. That is, it is possible to suppress the gloss unevenness of the image or the gloss unevenness. Therefore, it is also possible to cope with the high speed and miniaturization of the image forming apparatus.

[0169] In the above embodiment, an example is shown in which the pressing mechanism presses the flange supporting the fixing belt, but it may also be Fig.31 As shown in FIG. 1 , the pressure mechanism presses the shaft 21 d of the pressure roller 21 and pushes the pressure roller 21 toward the fixing belt 20. Fig.31 , the pressure mechanism is shown to pressurize the shaft 21 d of the pressure roller 21 , but the pressure may be applied to a bearing supporting the shaft of the pressure roller 21 .

[0170] In addition, the present invention is particularly suitable for a heater that is miniaturized in the short side direction. Specifically, it is preferable to apply the present invention to Fig.32 The heater 22 shown has a ratio (R / Q) of the short-side dimension R of the impedance heating element 59 to the short-side dimension Q of the heater 22 (base material 50) of 25% or more. Furthermore, the present invention is more preferably applicable to a heater 22 having the above-mentioned short-side dimension ratio (R / Q) of 40% or more. By applying the present invention to such a small heater 22, a greater effect can be expected.

[0171] In addition, in order to suppress the uneven temperature of the above-mentioned heater 22, a resistance heating element with PTC characteristics can also be used. The PTC characteristic refers to the characteristic that the resistance value increases when the temperature increases (the heater output power decreases when a constant voltage is applied). By adopting a heating part with a PTC characteristic, a rapid increase can be achieved through high output at low temperatures, and excessive temperature rise can be suppressed by low output at high temperatures. For example, if the TCR coefficient of the PTC characteristic is about 300 to 4000 ppm / degree, low cost can be achieved while ensuring the resistance value required for the heater. More preferably, the TCR coefficient is 500 to 2000 ppm / degree.

[0172] The temperature coefficient of resistance (TCR) can be calculated using the following formula (2). In formula (2), T0 is the reference temperature, T1 is the arbitrary temperature, R0 is the resistance value at the reference temperature T0, and R1 is the resistance value at the arbitrary temperature T1. Figure 7 In the above-mentioned heater 22 shown, when the resistance value between the first electrode 61A and the second electrode 61B is 10Ω (resistance value R0) at 25°C (reference temperature T0) and 12Ω (resistance value R1) at 125°C (arbitrary temperature T1), the resistance temperature coefficient calculated from the following formula (2) is 2000ppm / °C.

[0173] Temperature coefficient of resistance (TCR) = (R1-R0) / R0 / (T1-T0)×10 6 ···(2)

[0174] In addition, the heater to which the present invention is applicable is not limited to the heater having Figure 7 The heater 22 having a block-shaped (rectangular) impedance heating element 59 as shown in the figure may also be applicable to a heater 22 having an impedance heating element 59 in a shape obtained by folding a straight line as shown in FIG. 33(a) or FIG. 33(b), or a heater having an impedance heating element in another shape. In the figure, the colored portion represents the impedance heating element 59. FIG. 33(a) shows an example in which a portion of the power supply line 62A and 62D formed along the length direction of the heater 22 is extended in a direction intersecting the length direction. On the other hand, FIG. 33(b) shows an example in which a region including the power supply line 62A and 62D formed along the length direction of the heater 22 and bent in a direction intersecting the length direction is also formed as the impedance heating element 59.

[0175] In addition, the present invention can also be applied to other devices besides the above-mentioned fixing device. Figure 34 to Figure 36 The fixing device shown in FIG. Figure 34 to Figure 36 The structure of each fixing device shown will be briefly described.

[0176] first, Fig.34The fixing device 9 shown is configured such that a pressing roller 90 is arranged on the side opposite to the fixing belt 20 and the pressure roller 21, and the fixing belt 20 is sandwiched and heated by the pressing roller 90 and the heater 22. On the other hand, on the pressure roller 21 side, a nip forming member 91 is arranged on the inner periphery of the fixing belt 20. The nip forming member 91 is supported by the support 24, and the fixing belt 20 is sandwiched by the nip forming member 91 and the pressure roller 21 to form a nip N.

[0177] exist Fig.34 In the fixing device 9 shown, as described in the above embodiment, a pressure mechanism is provided for applying pressure to at least one of the fixing belt 20 and the pressure roller 21 and pressing the other side, so that the pressure on the side with a larger heat generation in the longitudinal direction of the heater 22 becomes relatively smaller than the pressure on the side with a smaller heat generation. As a result, the clamping pressure on the side with a larger heat generation in the longitudinal direction of the heater 22 becomes relatively smaller. Furthermore, the width of the clamping portion on the side with a larger heat generation in the longitudinal direction of the heater 22 becomes relatively smaller. Therefore, it is possible to suppress the adverse conditions caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 24. That is, it is possible to suppress the difference in fixing performance between one side and the other side in the longitudinal direction, and to suppress the gloss deviation in the longitudinal direction. Therefore, it is possible to suppress the image unevenness and gloss unevenness of the paper.

[0178] Then, in Fig.35 In the fixing device 9 shown in the figure, the aforementioned pressing roller 90 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.

[0179] Finally, Fig.36 The fixing device 9 shown in the figure is described. The fixing device 9 is composed of a heating component 92, a fixing roller 93 as a rotating member (fixing member), and a pressure component 94 as an opposing member. The heating component 92 includes the heater 22, the heating unit 19, and the heating belt 120 described in the above embodiment. In addition, the fixing roller 93 is composed of a solid iron core rod 21a, 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. In addition, a pressure component 94 is provided on the opposite side of the heating component 92 relative to the fixing roller 93. The pressure component 94 is configured with a nip forming member 95 and a support member 96, and a pressure belt 97 is configured to be rotatable in a manner including these nip forming member 95 and the support member 96. Then, the paper P is passed through the fixing nip N2 between the pressure belt 97 and the pressure roller 93, and the image is fixed by heating and pressurizing it.

[0180] exist Fig.36 In the fixing device 9 shown, since the heating component 92 heats the fixing roller 93, as mentioned above, when there is a deviation in the amount of heat between one side and the other side in the length direction (depth direction in the figure) of the heater 22, a temperature deviation will also occur in the fixing roller 93 on one side and the other side in the length direction.

[0181] So, in Fig.36 In the fixing device 9 shown, there is provided a pressing mechanism for pressing at least one of the fixing roller 93 as a rotating part (fixing part) and the pressing assembly 94 as an opposing part and pressing toward the other side, so that the pressing force on the side with a larger heating value in the longitudinal direction of the heater 22 becomes relatively smaller than the pressing force on the side with a smaller heating value. As a result, the clamping pressure on the side with a larger heating value in the longitudinal direction of the heater 22 becomes relatively smaller. Furthermore, the width of the clamping portion on the side with a larger heating value of the heater 22 becomes relatively smaller. Therefore, it is possible to suppress the adverse conditions caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 24. That is, it is possible to suppress the difference in fixing performance between one side and the other side in the longitudinal direction, and to suppress the gloss deviation in the longitudinal direction. Therefore, it is possible to suppress the image unevenness and gloss unevenness of the paper.

[0182] The layout of the electrodes and the like disposed on the base material 50 of the heater 22 is not limited to the above-described embodiment, and the present invention can also be applied to a heater that generates temperature deviation between one side and the other side in the longitudinal direction.

[0183] For example, as another example of a heater to which the present invention is applicable, Fig.37 The heater 22 shown is different from the previous embodiment in that all electrodes are arranged on one side in the length direction. Fig.10 Compared with the heater 22 of the embodiment of the present invention, the difference is that the second electrode 61B is arranged on one side in the length direction. Fig.37 As shown, since the second electrode 61B is provided on one side in the longitudinal direction, the power supply line directly connected to the second electrode 61B extends to the other side in the longitudinal direction, then turns back and is connected to each impedance heating element 59. In the present embodiment, the power supply line connecting these second electrodes 61B and each impedance heating element 59 from the portion connected to each impedance heating element 59 to the turned back portion on the other side in the longitudinal direction is referred to as the second power supply line 62B, and the portion extending continuously from the turned back portion toward one side in the longitudinal direction to the second electrode 61B is referred to as the fifth power supply line (conductor) 62E.

[0184] In such a heater 22 , when only the first heat generating portion 60A is energized, and when both the first heat generating portion 60A and the second heat generating portion 60B are energized, the above-mentioned temperature deviation in the longitudinal direction also occurs.

[0185] First, when only the first heating element 60A is energized, Fig.38 and Fig.39 As shown in FIG. 1 , an unexpected current diversion occurs toward the third power supply line 62C. Therefore, the total heat generation of each block is asymmetric with respect to the fourth block in the center of the heating area, and the heat generation on one side in the length direction is larger than that on the other side. In addition, when the first heating unit 60A and the second heating unit 60B are energized, as shown in FIG. Fig.40 and Fig.41 As shown, the total heat generation based on the fourth block is also asymmetric on the left and right, and the heat generation on the other side in the length direction is larger than that on one side.

[0186] Then, similarly to the above-mentioned embodiment, in the longitudinal direction of the heater 22, by making the pressing force generated by the pressing mechanism on the side with a larger heating value of the heater 22 relatively smaller than that on the side with a smaller heating value, the clamping pressure and the clamping width in the clamping part N on the side with a larger heating value of the heater 22 can be reduced, and the inconvenience caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 22 can be suppressed. That is, the difference in fixing performance between one side and the other side in the longitudinal direction can be suppressed, and the gloss deviation in the longitudinal direction can be suppressed. Therefore, the image unevenness and gloss unevenness of the paper can be suppressed.

[0187] 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, it is possible to suppress the adverse conditions caused by the temperature deviation between one side and the other side in the longitudinal direction of the heater 24.

[0188] The recording medium includes, in addition to paper P (plain paper), thick paper, postcards, envelopes, thin paper, coated paper (coated paper or coated paper, etc.), tracing paper, OHP sheets, and the like.

Claims

1. A heating device, comprising: Rotating parts; An opposing member that contacts the rotating member to form a clamping portion; a heating member for heating the rotating member, and a pressurizing mechanism for pressurizing at least one of the rotating member and the opposing member to press the rotating member against the other member; The heating device is characterized in that the heating component includes: A first heating part, comprising at least one impedance heating element; a second heating portion, comprising at least two impedance heating elements respectively located closer to both ends of the heating component in the length direction than the first heating portion; Multiple conductors; A first electrode connected to the first heating part through the conductor; a second electrode connected to the first heating portion and the second heating portion through the conductor, and a third electrode connected to the second heating portion through the conductor, When both the first heating unit and the second heating unit are energized, the pressurizing mechanism reduces the pressurizing force on the side opposite to the side where the first electrode is arranged relative to the pressurizing force on the side where the first electrode is arranged in the longitudinal direction of the heating component. When only the first heating part of the first heating part and the second heating part is energized, the pressurizing mechanism reduces the pressurizing force on the side where the first electrode is arranged relative to the pressurizing force on the opposite side where the first electrode is arranged in the longitudinal direction of the heating component.

2. The heating device according to claim 1, characterized in that: After the image forming operation of the image forming apparatus starts, the pressing mechanism reduces the pressing force on the side of the heating member with a larger heating value in the longitudinal direction relatively with respect to the pressing force on the side with a smaller heating value.

3. The heating device according to claim 2, characterized in that: After the image forming apparatus starts an image forming operation and performs a fixing operation on a predetermined number of recording media, the pressing mechanism reduces the pressing force on the side with a larger heating value in the longitudinal direction of the heating member relative to the pressing force on the side with a smaller heating value.

4. The heating device according to claim 2, characterized in that: The pressing mechanism reduces the pressing force on the side of the heating member with a larger heating value in the longitudinal direction relatively to the pressing force on the side with a smaller heating value after a predetermined time has passed since the image forming apparatus started the image forming operation.

5. The heating device according to claim 1, characterized in that: After the image forming operation of the image forming apparatus is completed, the pressing mechanism changes the pressing force on the one side and the other side in the longitudinal direction to be the same.

6. The heating device according to claim 1, characterized in that: It also includes a temperature detection mechanism that is opposite to the rotating member and is arranged on one side and the other side in the length direction of the heating member, When the temperature difference detected by the temperature detection means on the one side and the other side is equal to or greater than a predetermined value, the pressurizing means relatively reduces the pressurizing force on the side with the higher temperature detected by the temperature detection means relative to the pressurizing force on the side with the lower temperature.

7. The heating device according to claim 1, characterized in that: In a direction perpendicular to the long side direction of the heating member, when a direction different from the thickness direction of the heating member is taken as a short side direction, The ratio of the short-side dimension of the resistance heating element of the heating component to the short-side dimension of the heating component is greater than 25%.

8. The heating device according to claim 1, characterized in that: In a direction perpendicular to the longitudinal direction of the heating member, when a direction different from the thickness direction of the heating member is set as a short side direction, The ratio of the short-side dimension of the resistance heating element to the short-side dimension of the heating component is greater than 40%.

9. The heating device according to claim 1, characterized in that: The toner on the recording medium is fixed by heat.

10. An image forming device, characterized in that include: The heating device according to any one of claims 1 to 9.

Images