Heating device, fixing device, and image forming apparatus

Abstract

A heating device includes: a pair of rotating bodies that come into contact with each other to form a nip portion through which a sheet passes; a heater that heats at least one of the pair of rotating bodies; a temperature sensor for detecting the temperature of the heater; a conductor; a plurality of conductor supports that support the conductors; and a member that supports the plurality of conductor supports. The conductor has flexibility and is connected to the temperature sensor. The conductor support extends in a direction away from the heater and includes a first conductor support and a second conductor support. The first conductor supports face an outer side of a predetermined region of the heater in a width direction of the sheet, and are arranged at a first interval in the width direction. The second conductor supports face a predetermined region of the heater and are arranged at a second interval larger than the first interval in the width direction.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to a heating device, a fixing device, and an image forming apparatus. Background Art

[0002] An image forming apparatus such as a copy machine or a printer includes a fixing device as an example of a heating device. The fixing device heats a sheet carrying an unfixed image to fix the unfixed image to the sheet.

[0003] One type of fixing device includes a temperature sensor such as a thermistor or a thermostat provided on a heater holding member that holds a heater. The temperature sensor is connected to a controller via a conductor such as a wire. The controller controls the heat generated by the heater based on the temperature detected by the temperature sensor to maintain the temperature of the heater at an appropriate temperature.

[0004] Since the conductor connected to the temperature sensor is arranged near the heater that becomes high temperature, the conductor is preferably made of a material with heat resistance or protected by a covering material with heat resistance. However, selecting a material with heat resistance has disadvantages such as increasing manufacturing costs. In order to solve this disadvantage, Japanese Unexamined Patent Application Publication No. 2011-118246 discloses a structure including a plurality of protrusions, which are arranged on the back side of a heater holding component to support the conductor. The back side is opposite to the side holding the heater. Japanese Unexamined Patent Application Publication No. 2011-118246 claims that the above-mentioned structure reduces the contact area of ​​the conductor relative to the heater, which reduces the heat transferred from the heater holding component to the conductor and reduces the temperature rise of the conductor.

[0005] Citation list

[0006] Patent Literature

[0007] [PTL1] Japanese Unexamined Patent Application Publication No. 2011-118246 Summary of the invention

[0008] Technical issues

[0009] The temperature distribution of the heater is not always uniform as a whole. For example, when the sheet passes through the fixing device continuously, an uneven temperature distribution occurs in the heater. When a sheet having a width smaller than the width of the heating area of ​​the heater passes through the fixing device, the sheet does not absorb the heat of the heater in the area facing the non-sheet passing area of ​​the fixing device, and the sheet does not pass through the non-sheet passing area. As a result, heat is accumulated in the area facing the non-sheet passing area, and the temperature of the area becomes higher than the temperature in the area facing the sheet passing area of ​​the fixing device, and the sheet passes through the area. Therefore, in the heater, a temperature difference is generated between the area opposite to the sheet passing area and the area opposite to the non-sheet passing area. The above-mentioned Japanese Unexamined Patent Application Publication No. 2011-118246 discloses a plurality of protrusions that prevent heat from being transferred to the conductor, but does not take into account the influence of heat from the area of ​​the heater that may have a higher temperature than another area of ​​the heater on the conductor. It is necessary to reduce the temperature rise of the conductor in the area where the temperature may be higher than the temperature of other areas.

[0010] Solutions to the problem

[0011] According to an embodiment of the present disclosure, a heating device includes a pair of rotating bodies, a heater, a temperature sensor, a conductor, a plurality of conductor supports, and a component supporting the plurality of conductor supports. A pair of rotating bodies are in contact with each other to form a clamping portion through which a sheet passes. The heater heats at least one of the pair of rotating bodies. The temperature sensor detects the temperature of the heater. The conductor is flexible and connected to the temperature sensor. A plurality of conductor supports support the conductor and extend in a direction away from the heater. The plurality of conductor supports include a first conductor support and a second conductor support. The first conductor support faces the outside of a predetermined area of ​​the heater in the width direction of the sheet and is arranged at a first interval in the width direction. The second conductor support faces the predetermined area of ​​the heater and is arranged at a second interval greater than the first interval in the width direction. The component has a first side facing the heater and a second side opposite to the first side.

[0012] Effects of the Invention

[0013] According to the heating device of the present disclosure, it is possible to reduce the temperature increase of the conductor in a region where the temperature may be higher than that of other regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] A more complete understanding of the embodiments and many of the attendant advantages and features thereof can be readily obtained and understood from the following detailed description taken in conjunction with the accompanying drawings.

[0015] [ Figure 1 ]

[0016] Figure 1 is a schematic cross-sectional view of an imaging apparatus according to an embodiment of the present disclosure.

[0017] [ Figure 2 ]

[0018] Figure 2 is included in Figure 1 Schematic diagram of a fixing device in an imaging device.

[0019] [ Figure 3 ]

[0020] Figure 3 is a cross-sectional view of the fixing belt according to the present embodiment.

[0021] [ Figure 4 ]

[0022] Figure 4 is a plan view of the heater according to the present embodiment.

[0023] [ Figure 5 ]

[0024] Figure 5 is a perspective view of a connector connected to a heater according to the present embodiment.

[0025] [ Figure 6 ]

[0026] Figure 6 is a schematic diagram of a supporting structure in the fixing device according to the present embodiment, the supporting structure supporting lead wires connected to the temperature sensor.

[0027] [ Figure 7 ]

[0028] Figure 7 It is a schematic diagram of a support structure according to a modified example of the present embodiment.

[0029] [ Figure 8 ]

[0030] Figure 8 is a schematic diagram of a support structure according to another variation of the present embodiment.

[0031] [ Fig. 9 ]

[0032] Fig. 9 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0033] [ Fig.10 ]

[0034] Fig.10 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0035] [ Fig.11 ]

[0036] Fig.11 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0037] [ Fig.12 ]

[0038] Fig.12 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0039] [ Fig.13 ]

[0040] Fig.13 This is a schematic diagram showing an example of a protrusion having a height that is not compared.

[0041] [ Fig.14 ]

[0042] Fig.14 This is a schematic diagram showing another example of a protrusion having a height that is not compared.

[0043] [ Fig.15 ]

[0044] Fig.15 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0045] [ Fig.16 ]

[0046] Fig.16 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0047] [ Fig.17 ]

[0048] Fig.17 is a schematic diagram of a support structure according to yet another variation of the present embodiment.

[0049] [ Fig.18 ]

[0050] Fig.18 It is a schematic diagram for explaining the arrangement of the protrusions.

[0051] [ Fig.19 ]

[0052] Fig.19 It is a schematic diagram of the fixing device for explaining the shape of the protrusion.

[0053] [ Fig. 20 ]

[0054] Fig. 20 It includes Fig.19The shapes of the protrusions are schematic diagrams of the fixing device with protrusions of different shapes.

[0055] [ Fig.21 ]

[0056] Fig.21 It includes Fig.19 and Fig. 20 The shapes of the protrusions are schematic diagrams of the fixing device with protrusions of different shapes.

[0057] [ Fig. 22 ]

[0058] Fig. 22 It includes Figures 19 to 21 The shapes of the protrusions are schematic diagrams of the fixing device with protrusions of different shapes.

[0059] [ Fig.23 ]

[0060] Fig.23 is a schematic diagram of a fixing device according to still another modified example of the present embodiment.

[0061] [ Fig.24 ]

[0062] Fig.24 is a partial schematic diagram of a fixing device according to still another modified example of the present embodiment.

[0063] [ Fig.25 ]

[0064] Fig.25 is a top view of a thermistor with leads mounted on both sides of the thermistor.

[0065] [ Fig.26 ]

[0066] Fig.26 is a top view of a thermistor with leads mounted on one side of the thermistor.

[0067] [ Fig. 27 ]

[0068] Fig. 27 This is a schematic diagram showing a fixing device of an embodiment assembled in an image forming apparatus using an end feed reference system.

[0069] [ Fig.28 ]

[0070] Fig.28 is based on a different Figure 6 A schematic diagram of a support structure for supporting lead wires connected to a temperature sensor in a fixing device of the embodiment shown in FIG.

[0071] [ Fig.29 ]

[0072] Fig.29 is based on Fig.28 Schematic diagram of a support structure of a modified example of an embodiment.

[0073] [ Fig.30 ]

[0074] Fig.30 is based on Fig.28 A schematic diagram of a support structure of another variation of an embodiment of the present invention.

[0075] [ Fig.31 ]

[0076] Fig.31 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0077] [ Fig.32 ]

[0078] Fig.32 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0079] [ Fig.33 ]

[0080] Fig.33 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0081] [ Fig.34 ]

[0082] Fig.34 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0083] [ Fig.35 ]

[0084] Fig.35 It means Fig.13 , Fig.14 The figures of the different examples are schematic diagrams showing protrusions of heights that are not compared.

[0085] [ Fig.36 ]

[0086] Fig.36 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0087] [ Fig.37 ]

[0088] Fig.37 is based on Fig.28A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0089] [ Fig.38 ]

[0090] Fig.38 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0091] [ Fig.39 ]

[0092] Fig.39 Yes means Fig.28 Schematic diagram of an embodiment of a projection configuration.

[0093] [ Fig.40 ]

[0094] Fig.40 Yes means Fig.28 A schematic diagram of a fixing device of a protrusion shape of an embodiment.

[0095] [ Fig.41 ]

[0096] Fig.41 It includes Fig.40 Schematic diagram of a fixing device with protrusions of different shapes.

[0097] [ Fig.42 ]

[0098] Fig.42 It includes Fig.40 and Fig.41 Schematic diagram of a fixing device with protrusions of different shapes.

[0099] [ Fig.43 ]

[0100] Fig.43 It includes Figure 40 to Figure 42 Schematic diagram of a fixing device with protrusions of different shapes.

[0101] [ Fig.44 ]

[0102] Fig.44 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0103] [ Fig.45 ]

[0104] Fig.45 is based on Fig.28 A schematic diagram of a support structure of yet another variation of an embodiment of the present invention.

[0105] [ Fig.46 ]

[0106] Fig.46 is a schematic diagram of a fixing device including protrusions provided on a flange.

[0107] [ Fig.47 ]

[0108] Fig.47 It is used to indicate the assembly of an imaging device using an end-feed reference system. Fig.28 A schematic diagram of a fixing device of an embodiment of the present invention.

[0109] [ Fig.48 ]

[0110] Fig.48 Is with Figure 2 Schematic diagram of a fixing device with different structures of a fixing device.

[0111] [ Fig.49 ]

[0112] Fig.49 Is with Figure 2 and Fig.49 Schematic diagram of a fixing device with different structures of a fixing device.

[0113] [ Fig.50 ]

[0114] Fig.50 Is with Figure 2 , Fig.49 and Fig.50 Schematic diagram of a fixing device with different structures of a fixing device.

[0115] [ Fig.51 ]

[0116] Fig.51 Is with Figure 2 and Figures 49 to 50 Schematic diagram of a fixing device with different structures of a fixing device.

[0117] [ Fig.52 ]

[0118] Fig.52 Is with Figure 1 Schematic diagram of an imaging device with different configurations of the imaging device.

[0119] [ Fig.53 ]

[0120] Fig.53 yes Fig.52 A schematic diagram of the fixing device is shown.

[0121] [ Fig.54 ]

[0122] Fig.54 yes Fig.53 A plan view of the heater is shown.

[0123] [ Fig.55 ]

[0124] Fig.55 yes Fig.53 A partial perspective view of the heater support and heater shown.

[0125] [ Fig.56 ]

[0126] Fig.56 Yes means to connect the connector to Fig.53 FIG. 10 shows a method of using a heater.

[0127] [ Fig.57 ]

[0128] Fig.57 Yes means included in Fig.53 A diagram showing the arrangement of a temperature sensor and a thermostat in a fixing device.

[0129] [ Fig.58 ]

[0130] Fig.58 Yes means Fig.56 Schematic diagram of the groove of the flange shown.

[0131] [ Fig.59 ]

[0132] Fig.59 Is with Figure 2 , Figures 49 to 51 and Fig.53 Schematic diagram of a fixing device with different structures of a fixing device.

[0133] [ Fig.60 ]

[0134] Fig.60 yes Fig.59 A three-dimensional view of the heater, the first high thermal conductivity component and the heater bracket shown.

[0135] [ Fig.61 ]

[0136] Fig.61 It is a plan view for explaining a heater in which the first high thermal conductive member is provided.

[0137] [ Fig.62 ]

[0138] Fig.62 It is a plan view of a heater for explaining another example of disposing the first high thermal conductive member.

[0139] [ Fig.63 ]

[0140] Fig.63 This is a plan view of a heater for explaining still another example of disposing the first high thermal conductive member.

[0141] [ Fig.64 ]

[0142] Fig.64 is a plan view of the heater showing the separation area magnified.

[0143] [ Fig.65 ]

[0144] Fig.65 Is with Figure 2 , Figures 49 to 51 , Fig.53 and Fig.59 Schematic diagram of a fixing device with different structures of a fixing device.

[0145] [ Fig.66 ]

[0146] Fig.66 yes Fig.65 A three-dimensional view of the heater, the first high thermal conductivity component, the second high thermal conductivity component and the heater bracket is shown.

[0147] [ Fig.67 ]

[0148] Fig.67 It is a plan view of a heater for explaining the arrangement of a first highly thermally conductive member and a second highly thermally conductive member.

[0149] [ Fig.68 ]

[0150] Fig.68 FIG. 2 is a diagram showing another arrangement of the first highly thermally conductive member and the second highly thermally conductive member.

[0151] [ Fig.69 ]

[0152] Fig.69 It is a plan view of a heater showing another example of the arrangement of the second highly thermally conductive member.

[0153] [ Fig.70 ]

[0154] Fig.70 Is with Figure 2 , Figures 49 to 51 , Fig.53 , Fig.59 and Fig.65 Schematic diagram of a fixing device with different structures of a fixing device.

[0155] [ Fig.71 ]

[0156] Fig.71 A schematic diagram showing the two-dimensional atomic crystal structure of graphene.

[0157] [ Fig.72 ]

[0158] Fig.72 It is a schematic diagram showing the three-dimensional atomic crystal structure of graphite.

[0159] The accompanying drawings are intended to describe embodiments of the present disclosure and should not be interpreted as limiting the scope thereof. Unless explicitly noted, the accompanying drawings should not be considered to be drawn to scale. Moreover, throughout the several views, the same or similar reference numerals represent the same or similar components. DETAILED DESCRIPTION

[0160] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings showing embodiments of the present invention, components or parts having the same or similar functions or shapes are given similar reference numerals as long as they are distinguishable, and redundant descriptions are omitted.

[0161] Figure 1 1 is a schematic cross-sectional view of an imaging device 100 according to an embodiment of the present disclosure. In the following description, an "imaging device" includes a printer, a copier, a scanner, a fax machine, or a multifunction machine having at least two functions of printing, copying, scanning, and faxing. The term "imaging" refers to an action for providing (i.e., printing) not only images with meaning (such as text and graphics) on a recording medium, but also images without meaning (such as patterns) on a recording medium. First, referring to Figure 1 , a description is given of the overall configuration and action of the imaging device 100 according to the present embodiment.

[0162] like Figure 1 As shown, the imaging device 100 of this embodiment includes: an imaging unit 200, which forms an image on a sheet-like recording medium such as paper; a fixing unit 300, which fixes the image on the recording medium; a recording medium conveying unit 400, which conveys the recording medium to the imaging unit 200; and a recording medium discharging unit 500, which discharges the recording medium to the outside of the imaging device 100.

[0163] The image forming section 200 includes four process units 1Y, 1M, 1C, and 1Bk as image forming units, an exposure device 6 that forms an electrostatic latent image on a photoreceptor 2 in each of the process units 1Y, 1M, 1C, and 1Bk, and a transfer device 8 that transfers the image to a recording medium.

[0164] The process units 1Y, 1M, 1C, and 1Bk have the same configuration except that they contain toners (developers) of different colors corresponding to the decomposed color separation components of the full-color image, namely, yellow (Y), magenta (M), cyan (C), and black (Bk) toners. Specifically, each of the process units 1Y, 1M, 1C, and 1Bk includes: a photoreceptor 2 serving as an image carrier carrying an image on its surface; a charger 3 for charging the surface of the photoreceptor 2; a developing device 4 for supplying a toner as a developer to the surface of the photoreceptor 2 to form a toner image; and a cleaner 5 for cleaning the surface of the photoreceptor 2.

[0165] The transfer device 8 includes an intermediate transfer belt 11, a primary transfer roller 12, and a secondary transfer roller 13. The intermediate transfer belt 11 is an endless belt stretched by a plurality of supporting rollers. Four primary transfer rollers 12 are arranged inside the loop of the intermediate transfer belt 11. Each primary transfer roller 12 contacts the corresponding photoreceptor 2 via the intermediate transfer belt 11 to form a primary transfer nip between the intermediate transfer belt 11 and each photoreceptor 2. The secondary transfer roller 13 contacts the outer peripheral surface of the intermediate transfer belt 11 to form a secondary transfer nip.

[0166] The fixing section 300 includes a fixing device 20. The fixing device 20 includes a fixing belt 21 as an endless belt and a pressure roller 22 as a relatively rotating body opposed to the fixing belt 21. The fixing belt 21 and the pressure roller 22 contact each other at their outer peripheral surfaces to form a nip (i.e., a fixing nip).

[0167] The recording medium feeder 400 includes a sheet tray 14 for storing a sheet P as a recording medium and a feed roller 15 for feeding the sheet P from the sheet tray 14. In addition, in the following embodiments, the "recording medium" is described as "paper" (abbreviated as "paper"), but the "recording medium" is not limited to paper. Examples of the "recording medium" include not only paper but also transparent sheets for overhead projectors (OHP), fabrics, metal sheets, plastic films, and prepreg sheets including carbon fibers pre-impregnated with resin. As "sheets", in addition to ordinary paper, thick paper, postcards, envelopes, thin paper, coated paper (e.g., coated paper, coated paper), tracing paper, etc. can also be cited.

[0168] The recording medium discharge section 500 includes an output roller pair 17 for discharging the sheet P to the outside of the image forming apparatus 100 and an output tray 18 for placing the sheet P discharged by the output roller pair 17 .

[0169] In order to provide a more comprehensive understanding of the embodiments of the present disclosure, reference is now made to Figure 1 A description is given of a printing action of the image forming apparatus 100 according to the present embodiment.

[0170] When the image forming apparatus 100 starts a printing action, the photosensitive bodies 2 of the process units 1Y, 1M, 1C, and 1Bk and the intermediate transfer belt 11 of the transfer device 8 start rotating. The paper feed roller 15 starts rotating to feed the sheet P from the sheet tray 14. The sheet P fed from the sheet tray 14 contacts the timing roller pair 16 and temporarily stops until the image forming section 200 forms an image to be transferred to the sheet P.

[0171] First, in each of the processing units 1Y, 1M, 1C and 1Bk, the charger 3 uniformly charges the surface of the photoreceptor 2 to a high potential. Next, the exposure device 6 exposes the surface (i.e., the charged surface) of each photoreceptor 2 based on the image data of the original document read by the original document reading device or the print image data sent from the terminal that sends the print instruction. As a result, the potential of the exposed portion on the surface of each photoreceptor 2 is reduced, and an electrostatic latent image is formed on the surface of each photoreceptor 2. The developing device 4 supplies colorant to the electrostatic latent image formed on the photoreceptor 2, forming a toner image thereon. When the toner image formed on the photoreceptor 2 reaches the primary transfer nip defined by the primary transfer roller 12 as the photoreceptor 2 rotates, the toner image formed on the photoreceptor 2 is continuously transferred to the primary transfer roller 12. Figure 1 The image forming apparatus 100 is transferred to the intermediate transfer belt 11 which rotates counterclockwise in the middle of the transfer belt 11, so that the toner image is superimposed on the intermediate transfer belt 11, and a full-color toner image is formed thereon. Therefore, a full-color toner image is formed on the intermediate transfer belt 11. The image forming apparatus 100 can use any one of the four process units 1Y, 1M, 1C, and 1Bk to form a single-color toner image, or can use two or three of the process units 1Y, 1M, 1C, and 1Bk to form a two-color toner image or a three-color toner image. After the toner image is transferred from the photoreceptor 2 to the intermediate transfer belt 11, the cleaner 5 removes the residual toner remaining on the photoreceptor 2 from the photoreceptor 2.

[0172] According to the rotation of the intermediate transfer belt 11, the toner image transferred onto the intermediate transfer belt 11 is conveyed to the secondary transfer nip portion (position of the secondary transfer roller 13), and is transferred onto the sheet P conveyed by the timing roller pair 16. The sheet P carrying the full-color toner image is conveyed to the fixing device 20. In the fixing device 20, the fixing belt 21 and the pressure roller 22 apply heat and pressure to the toner image on the sheet P to fix the toner image onto the sheet P. Then, the sheet P carrying the fixed toner image is conveyed to the recording medium discharge portion 500. In the recording medium discharge portion 500, the output roller pair 17 discharges the sheet P onto the output tray 18. Thus, a series of printing actions are completed.

[0173] Next, refer to Figure 2 , a description is given of the configuration of the fixing device 20 according to the present embodiment.

[0174] like Figure 2 As shown, the fixing device 20 according to the present embodiment includes a heater 23 , a heater support 24 , a stay 25 , a guide 26 , and a temperature sensor 27 in addition to the fixing belt 21 and the pressure roller 22 .

[0175] The fixing belt 21 is a rotating body as a first rotating body or a fixing rotating body, which contacts the surface of the sheet P carrying the unfixed toner image and fixes the unfixed toner image to the sheet P. The loop diameter of the fixing belt 21 is, for example, in the range of 15 mm to 120 mm. In the present embodiment, the fixing belt 21 has an inner diameter of 25 mm.

[0176] like Figure 3 As shown, the fixing belt 21 includes a base layer 210, an elastic layer 211 and a release layer 212 stacked in sequence from the inner peripheral surface side to the outer peripheral surface side, and has a total thickness set to not more than 1 mm. The film thickness of the base layer 210 is 30μm to 50μm, and is formed of a metal material such as nickel, stainless steel, or a resin material such as polyimide. The elastic layer 211 has a layer thickness of 100μm to 300μm and is made of a rubber such as silicone rubber, silicone rubber foam, or fluororubber. The elastic layer 211 of the fixing belt 21 absorbs the tiny concavoconvexities on the surface of the fixing belt 21 in the fixing nip formed between the fixing belt 21 and the pressure roller 22, and promotes uniform heat conduction from the fixing belt 21 to the color toner image T on the sheet P. The release layer 212 of the fixing belt 21 has a film thickness of 10 μm to 50 μm and is formed of a material such as tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), polytetrafluoroethylene (PTFE), polyimide, polyetherimide, polyethersulfone (PES), etc. The release layer 212 of the fixing belt 21 facilitates the separation of the toner in the toner image on the sheet P from the fixing belt 21. In other words, the release layer 212 of the fixing belt 21 ensures that the toner is peeled off from the fixing belt 21.

[0177] like Figure 2 As shown, the pressure roller 22 is a rotating body as a second rotating body or an opposing rotating body, and is arranged to face the outer peripheral surface of the fixing belt 21. The pressure roller 22 contacts the fixing belt 21 on the heater 23 to form a fixing nip portion therebetween.

[0178] The pressure roller 22 has an outer diameter of, for example, 25 mm, and includes a hollow iron core 220, an elastic layer 221 provided on the outer peripheral surface of the iron core 220, and a release layer 222 provided on the outer peripheral surface of the elastic layer 221. The elastic layer 221 has a thickness of, for example, 3.5 mm and is made of silicone rubber, etc. The release layer 222 has a thickness of, for example, about 40 μm and is made of fluororesin, etc.

[0179] The heater 23 is a heat source for heating the inner peripheral surface of the fixing belt 21. The heater 23 is a planar heater extending in the length direction of the fixing belt 21 (i.e., the width direction of the sheet intersecting the sheet conveying direction). The heater 23 is arranged to contact the inner peripheral surface of the fixing belt 21. The heater 23 of this embodiment includes: a substrate 55, a resistance heating element 56 arranged on the substrate 55, and an insulating layer 57 covering the resistance heating element 56.

[0180] Although the resistance heating element 56 is provided on the surface of the substrate 55 on the pressure roller 22 side (in other words, on the fixing nip N side) in the present embodiment, the resistance heating element 56 may alternatively be provided on the surface on the opposite side of the substrate 55. In this case, since the heat of the resistance heating element 56 is transferred to the fixing belt 21 through the substrate 55, it is preferable that the substrate 55 is made of a material having high thermal conductivity (e.g., aluminum nitride).

[0181] The heater holder 24 is arranged inside the loop of the fixing belt 21, and is a heat source holding member that holds the heater 23. Since the temperature of the heater holder 24 rises due to the influence of the heat from the heater 23, the heater holder 24 is preferably made of a heat-resistant material. For example, the heater holder 24 made of a heat-resistant resin with low thermal conductivity such as liquid crystal polymer (LCP) and polyetheretherketone (PEEK) has heat resistance and can suppress heat transfer from the heater 23 to the heater holder 24. As a result, the heater 23 can effectively heat the fixing belt 21.

[0182] The support 25 supports the heater bracket 24. The support 25 supports the surface of the heater bracket 24 opposite to the surface on the pressure roller 22 side, extends in the length direction of the fixing belt 21, suppresses the heater bracket from being bent due to the pressure of the pressure roller 22, and forms a fixing nip N with a uniform width between the fixing belt 21 and the pressure roller 22.

[0183] In order to ensure rigidity, the support column 25 is preferably formed of an iron-based metal such as stainless steel (SUS) or electrolytic cold-rolled steel, that is, electrogalvanized steel sheet (SECC).

[0184] The guide 26 guides the inner peripheral surface of the fixing belt 21. The guide 26 has an arc-shaped cross-sectional shape along the inner peripheral surface of the fixing belt 21. The guide 26 has a rotation direction ( Figure 2 The fixing device includes an upstream side portion located upstream of the heater 23 in the direction indicated by the arrow in the figure and a downstream side portion located downstream of the heater 23 in the rotation direction. Instead of the upstream side portion and the downstream side portion, the fixing device may include an upstream guide and a downstream guide. In the present embodiment, the guide 26 is formed integrally with the heater bracket 24, but may also be formed separately.

[0185] The temperature sensor 27 is a temperature detector that detects the temperature of the heater 23. The temperature sensor 27 may be a known temperature sensor, such as a thermopile, a thermostat, a thermistor, or a non-contact (NC) sensor. The temperature sensor 27 of the present embodiment is a contact-type temperature sensor that contacts the support side of the heater 23 and detects the temperature of the heater 23. The support side of the heater 23 is opposite to the clamping side of the heater 23 that faces the pressure roller 22. The temperature sensor 27 is not limited to a contact-type temperature sensor. The temperature sensor 27 may be a non-contact temperature sensor that is arranged not to contact the heater 23.

[0186] The fixing device 20 constructed as described above operates as follows.

[0187] like Figure 2 As shown, when the driver drives and rotates the pressure roller 22, the driving force of the driver is transmitted from the pressure roller 22 to the fixing belt 21, so that the fixing belt 21 is rotated according to the rotation of the pressure roller 22 by the friction between the fixing belt 21 and the pressure roller 22. The heater 23 heats the fixing belt 21. The temperature sensor 27 detects the temperature of the heater 23 at this time, and the control part controls the heating amount of the heater 23 according to the detected temperature. Therefore, the controller maintains the temperature of the fixing belt 21 to a fixing temperature at which the fixing belt 21 can fix the unfixed colorant image to the sheet. The sheet P carrying the unfixed colorant image is conveyed to the fixing nip N between the fixing belt 21 and the pressure roller 22, and the fixing belt 21 and the pressure roller 22 apply heat and pressure to the sheet P to fix the unfixed colorant image to the sheet P.

[0188] Figure 4 It is a plan view of the heater according to this embodiment.

[0189] like Figure 4 As shown, the heater 23 of this embodiment has a Figure 4 The substrate 55 is a planar substrate extending in the direction indicated by the arrow X in FIG. The substrate 55 is configured so that the length direction X of the substrate 55 is parallel to the length direction X of the fixing belt 21 or the axial direction of the pressure roller 22. On the surface of the substrate 55, two resistive heating elements 56 extend in the length direction X of the substrate 55 and are arranged side by side in the short side direction Y of the substrate 55. The so-called "short side direction" refers to the direction orthogonal to the length direction X along the surface of the substrate 55 on which the resistive heating elements 56 are arranged. The short side direction is also the same direction as the sheet conveying direction of the conveyed sheet.

[0190] like Figure 4 As shown, a pair of electrodes 58 is disposed at one end of the substrate 55 in the longitudinal direction X. Each electrode 58 is connected to one end of each resistance heating element 56 via a power supply line 59.

[0191] Each of the resistance heating elements 56 has the other end opposite to the one end connected to each electrode 58. Another power supply line 59 connects the other ends of the two resistance heating elements 56. The insulating layer 57 covers the resistance heating elements 56 and the power supply lines 59 to insulate the resistance heating elements 56 and the power supply lines 59 from other components. On the other hand, the electrode 58 is not covered by the insulating layer 57 but is exposed so that a connector as a power supply terminal described later can be connected.

[0192] The substrate 55 is formed of a material with excellent heat resistance and insulation, such as ceramics such as polyimide, glass, mica, aluminum oxide or aluminum nitride. Or the substrate 55 may include a metal plate made of a metal (i.e., a conductive material) such as SUS, iron or aluminum, and an insulating layer formed on the metal plate. In particular, the substrate 55 includes a metal plate made of a high thermal conductivity material such as aluminum, copper, silver, graphite or graphene, which improves the thermal uniformity and image quality of the heater 23. The insulating layer 57 is made of a material with excellent heat resistance and insulation, such as polyimide, glass, mica, or ceramic (such as aluminum oxide or aluminum nitride). The resistive heating element 56 is manufactured, for example, as follows: silver-palladium (AgPd), glass powder, etc. are mixed to prepare a paste. The paste is screen-printed on the surface of the substrate 55. Then, the substrate 55 is sintered. Thus, the resistive heating element 56 is manufactured. The material of the resistive heating element 56 may contain a resistive material, such as a silver alloy (e.g., AgPt) or ruthenium oxide (RuO2). The electrode 58 and the power supply line 59 are formed by screen printing silver (Ag) or silver-palladium (AgPd).

[0193] Figure 5 2 is a perspective view of a connector 40 as a power supply member connected to the heater 23.

[0194] like Figure 5 As shown, the connector 40 includes: a resin housing 41; a plurality of contact terminals 42, which are arranged in the housing 41; and a wiring harness 43, which includes electric wires connected to each contact terminal 42 for power supply. Each contact terminal 42 is composed of a component that can be elastically deformed, such as a leaf spring.

[0195] like Figure 5 As shown, the connector 40 is installed on the heater 23 and the heater bracket 24 in a manner of clamping the heater 23 and the heater bracket 24. Thus, the connector 40 holds the heater 23 and the heater bracket 24 together. In the above state, the contact portion 42a at the end of the contact terminal 42 provided in the connector 40 elastically contacts and presses against the respectively corresponding electrodes 58 to electrically connect the electrodes 58 and the contact terminal 42 respectively. The above configuration enables the power supply provided in the main body of the imaging device to supply power to each of the resistive heating elements 56 in the heater 23 via the connector 40.

[0196] Figure 62 is a schematic diagram of a supporting structure for supporting lead wires 44 connected to the temperature sensor 27 in the fixing device according to the present embodiment.

[0197] like Figure 6 As shown, the temperature sensor 27 is connected to one end of a flexible lead wire 44 as a conductor. The other end of the lead wire 44 is connected to a controller provided in the main body of the imaging device. The lead wire 44 includes a wire and an insulator covering the wire to ensure insulation and heat resistance. The lead wire 44 is provided on the support side of the heater support 24 to avoid direct influence of heat of the heater 23 facing the clamping side of the heater support 24 opposite to the support side. That is, the lead wire 44 is provided on the first surface 240 ( Figure 6 The first surface 240 is opposite to the second surface 241 of the heater support 24, and the second surface 241 holds the heater 23. On the first surface 240 of the heater support 24 opposite to the lead 44, a plurality of protrusions 30 serving as a conductor support for supporting the lead 44 are provided.

[0198] The plurality of protrusions 30 are arranged at intervals in the length direction of the heater support 24 (also the length direction X of the heater 23). The front end of each protrusion 30 supports the lead 44 so that a gap is formed between the lead 44 and the flat base 31 of the heater support 24 on which the protrusion 30 is arranged, thereby preventing the lead 44 from contacting the base 31. In other words, the heater support 24 includes a flat base 31 having a first surface 240 and a second surface 241 opposite to the first surface 240. A recess 24a for holding the heater 23 is formed on the second surface 241. On the first surface 240, a plurality of protrusions 30 are provided. As described above, the plurality of protrusions 30 supporting the lead 44 avoid contact between the lead 44 and the base 31, and reduce the contact area of ​​the lead 44 relative to the heater support 24. The lead 44, which has a lower rigidity than a metal plate, a jumper wire, etc., requires a component for supporting the lead 44 to keep the lead 44 at a position away from the heater support 24. Therefore, the heater support 24 of this embodiment has a plurality of protrusions 30 for supporting the lead wires 44, so that the contact area between the lead wires 44 and the heater support 24 can be reduced, and heat transfer from the heater 23 and the heater support 24 to the lead wires 44 can be prevented. Figure 6 In the embodiment, the fixing device includes two lead wires 44, but may include one lead wire including two lead wires and an insulator covering the two lead wires.

[0199] The lead wire 44 may not be in contact with the front end of the protrusion 30. That is, in addition to the protrusion 30 that contacts the lead wire 44, the protrusion 30 that supports the lead wire 44 and does not contact the base 31 of the heater support 24 also includes a protrusion that does not always contact the lead wire 44. For example, Figure 8The protrusion 30A2 shown does not actually contact the lead 44. However, when the lead 44 approaches the base 31, the protrusion 30A2 supports the lead 44 so that it does not contact the base 31. In the present invention, the protrusion 30 supporting the lead 44 includes the protrusion 30A2.

[0200] exist Figure 6 Among the plurality of protrusions 30, the one located closest to the end in the length direction of the heater support 24 ( Figure 6 The protrusion 30A at the right end in FIG. 1 is set to be higher than the height of the other protrusions 30B in the protruding direction from the heater support 24 (ie, the base 31). Figure 6 The protrusion 30A which is higher than the other protrusions 30B corresponds to the portion where the temperature of the heater 23 becomes higher than the temperature of the other portions of the heater 23 to prevent the heat of the heater 23 from affecting the lead 44 .

[0201] Specifically, in the present embodiment, the portion of the heater 23 where the temperature of the heater 23 is higher than the temperature of the other portion of the heater 23 is the portion (inside the heat generating area 60 in which the resistance heating element 56 of the heater 23 is arranged) which is further outside than the maximum passing paper width W1 (maximum sheet passing width) through which the paper P1 of the maximum width passes. Figure 6 In addition, the "heating area" in this specification refers to the area where the resistance heating element 56 is arranged in the longitudinal direction X of the heater 23. Fig.18), in the case where a plurality of resistance heating elements 56 are arranged, it refers to the range from one end to the other end of the area where all the resistance heating elements 56 are arranged. In addition, the "maximum paper passing width" in this specification refers to an area pre-set on the assumption that paper of the maximum width passes, regardless of whether paper of the maximum width actually passes. The sheet with the maximum width in this specification is a sheet with the maximum width among the sheets recorded in the user manual, catalog, etc. of the imaging device. Similarly, the sheet with the minimum width in this specification is a sheet with the minimum width among the sheets recorded in the user manual, catalog, etc. of the imaging device. In the case of this embodiment, the so-called center reference conveying method is adopted, which uses the center in the width direction of each as a reference to align and convey papers of various width sizes, so the range from the center m in the long side direction of the heating area 60 of the heater 23 toward the two end sides to a distance half of the maximum width of the paper, or a distance of 5 mm added to half of the maximum width is the maximum passing paper width. For example, when the maximum width of the paper is A4 size (width: 210 mm), the maximum width of the paper is the range from the center m in the longitudinal direction of the heating area 60 toward the two ends to the position of 105 mm, which is half the distance of the A4 size, or the position of 110 mm, which is 105 mm plus 5 mm. Figure 6 In the figure, the area indicated by the symbol W2 is the minimum paper width (minimum sheet width) through which the paper P2 with the minimum width passes. This minimum paper width is also the same as the maximum paper width, and is an area set in advance assuming that the paper with the minimum width passes regardless of whether the paper with the minimum width actually passes. That is, the range from the center m in the longitudinal direction of the heating area 60 of the heater 23 toward both ends to a distance of half the minimum width of the paper or a distance of half the minimum width plus 5 mm is the minimum paper width.

[0202] The basic point of heating the sheet is to maintain the temperature of the fixing belt 21 facing the maximum sheet passing area W1 at a predetermined temperature. However, since the heat storage amount of the fixing belt 21 is small after the temperature of the fixing belt 21 is raised to the predetermined temperature, the sheet passing through the fixing belt 21 easily causes the temperature of the fixing belt 21 to drop at both ends of the heating area 60. Therefore, in the present embodiment, the heating area 60 of the heater 23 is extended to the outside of the maximum sheet passing area W1 to prevent the temperature of the fixing belt 21 from dropping due to the sheet passing on the fixing belt 21. However, if the heating area 60 is extended to the outside of the maximum sheet passing area W1, when many sheets are continuously passed, in the non-sheet passing area where the sheet P1 of the maximum width does not pass, the fixing belt 21 and the heater 23 store heat and cause an excessive rise in temperature.

[0203] The sheet that may cause the temperature rise in the non-sheet passing area is not limited to the sheet P1 having the maximum width. If the sheet has a width smaller than the heating area 60 of the heater 23 and passes through the fixing device, the temperature rise may occur. In the case of small-sized sheets with low usage frequency, the imaging device usually adopts a countermeasure of reducing productivity (i.e., printing speed) in order to suppress the temperature rise in the non-sheet passing area. In contrast, in the case of the paper P1 with the maximum width and high usage frequency, because there is a tendency to print without reducing productivity, it is easy to cause a temperature rise in the non-sheet passing area when the paper passes continuously. In addition, in recent years, with the increase in the heat generated by the heater due to the high speed of the imaging device, the problem of excessive temperature rise outside the maximum paper passing width W1 has become significant.

[0204] In order to solve this disadvantage, the fixing device 20 according to the embodiment of the present disclosure includes the following Figure 6 The protrusion 30A and the protrusion 30B shown. The protrusion 30A is provided on the area of ​​the heater support 24 facing the area H (hereinafter referred to as the "excessive temperature rise area" for convenience), which is located inside the heat generation area 60 of the heater 23 in the width direction and outside the maximum sheet passing area W1 in the width direction. The protrusion 30A is higher than the protrusion 30B provided on the heater support 24 facing the area other than the area H, that is, Figure 6 As a result, the distance from the lead 44 to the excessive temperature rise area H of the heater 23 is larger than the distance from the lead 44 to the area outside the area H. Figure 6 , the distance from the lead wire 44 to the heater 23 is measured along a direction orthogonal to the width direction and the sheet conveying direction.

[0205] In the above-described structure, heat is hardly transferred from the heater 23 to the lead wire 44. Even if the sheets P1 each having the maximum width continuously pass through the fixing device and cause excessive temperature rise in the excessive temperature rise region H of the heater 23, the above-described configuration can prevent temperature rise of the lead wire 44, which can prevent deterioration and damage of the lead wire 44. The above-described configuration capable of preventing deterioration and damage of the lead wire 44 enables continuous printing of the sheets P1 having the maximum width without reducing productivity.

[0206] The position of the protrusion 30A higher than the protrusion 30B is not limited to Figure 6 The position opposite to the excessive temperature rise region H shown may be a position opposite to the outer side of the excessive temperature rise region H in the longitudinal direction X of the heater holder 24 .

[0207] For example, Figure 7As shown in FIG. 2 , the heater holder 24 may be provided with protrusions 30A that are higher than the protrusions 30B on both outer sides in the width direction of the excessive temperature rise region H. Figure 7 The structure shown can ensure that the distance from the lead 44 to the excessive temperature rise area H of the heater 23 is greater than the distance from the lead 44 to other areas, thereby suppressing the temperature rise of the lead 44. Figure 7 The protrusion 30A shown is not opposite to the excessive temperature rise area H, so according to the above structure, the temperature rise of the protrusion 30A itself can be suppressed. By suppressing the temperature rise of the protrusion 30A itself, the heat transferred from the protrusion 30A to the lead 44 can be reduced. As a result, according to the above structure, the temperature rise of the lead 44 can be effectively suppressed. By effectively suppressing the temperature rise of the lead 44, an inexpensive material (a material with not too high heat resistance) can be selected as the material of the lead 44 or the insulator covering the lead 44, thereby achieving cost reduction. On the other hand, in Figure 6 In the fixing device 20 shown in FIG. 1 , the end of the heater support 24 opposite to the outer side of the overheating region H in the longitudinal direction of the heater support 24 does not have the protrusion 30A. Figure 6 In the structure shown, the space for arranging the protrusion 30A at the end of the heater holder 24 can be omitted, which has the advantage that the dimension of the heater holder 24 in the longitudinal direction can be reduced.

[0208] In addition, if Figure 8 As shown, it is also possible that, among the protrusions 30A that are higher than the protrusions 30B, the protrusions 30A1 from the right side of the overheating region H toward the outside are higher than the protrusions 30A2 from the left side of the overheating region H toward the inside. Figure 8 , t3>t4. In this example, the lead 44 is mainly supported by the higher protrusion 30A1. The higher protrusion 30A1 toward the outside in the width direction from the heat generating area 60 is less susceptible to the heat of the heater 23 than the protrusion 30A2 toward the heat generating area 60. Since the amount of heat transferred from the higher protrusion 30A1 to the lead 44 is less than the amount of heat transferred from the protrusion 30A2 to the lead 44, the above-mentioned structure can effectively suppress the temperature rise of the lead 44.

[0209] On the contrary, Fig. 9 As shown, in the protrusion 30A which is higher than the protrusion 30B, the protrusion 30A2 from the left side of the excessive temperature rise region H toward the inside may be higher than the protrusion 30A1 from the right side of the excessive temperature rise region H toward the outside, that is, Fig. 9 According to Fig. 9 The structure shown can reduce the height of the protrusion 30A1 arranged at the end portion in the longitudinal direction of the heater holder 24, thereby increasing the degree of freedom in designing the wiring of the lead wires 44.

[0210] Next, the following describes Fig.10 The embodiment shown in Fig.10 In the illustrated embodiment, the protrusion 30A1 provided at the end of the heater support 24 outside the excessive temperature rise region H in the longitudinal direction of the heater support 24 is closer to the longitudinal end side of the heater support 24 than the end 620 of the roller portion 62 (the portion having the elastic layer) of the pressure roller 22 in the longitudinal direction ( Fig.10 According to the above structure, by arranging the protrusion 30A1 outside the excessive temperature rise region H and outside the roller portion 62 of the pressure roller 22 in the length direction, it is possible to prevent heat from being transferred from the pressure roller 22 to the protrusion 30A1 arranged outside the excessive temperature rise region H via the heater holder 24, and it is possible to suppress the temperature rise of the protrusion 30A1. By suppressing the temperature rise of the protrusion 30A1, it is possible to suppress the heat transferred from the protrusion 30A1 to the lead 44. As a result, according to the above structure, the temperature rise of the lead 44 can be effectively suppressed.

[0211] In addition, if Fig.10 As shown in FIG. 1 , when a heat spreader 28 as a heat conduction auxiliary component is provided between the heater 23 and the heater support 24, it is preferable to suppress the influence of heat transferred from the heat spreader 28 to the protrusion 30A1. The heat spreader 28 is made of a material having a higher thermal conductivity than the heater support 24, such as copper, aluminum, or silver. The heat spreader 28 moves the heat from the heater 23 along the length direction of the fixing belt 21 to uniformly heat the fixing belt 21. Fig.10 As shown, outside the excessive temperature rise region H in the longitudinal direction of the heater support 24, the protrusion 30A1 arranged at the end of the heater support 24 is closer to the end of the heater support 24 in the longitudinal direction than the end 280 of the heat spreader 28 in the longitudinal direction ( Fig.10 The right side of the heater bracket 24 in the middle) can suppress the heat transfer from the heat spreader 28 to the protrusion 30A1 outside the excessive temperature rise area H in the length direction, and can effectively suppress the temperature rise of the protrusion 30A1.

[0212] In the above-mentioned embodiments, in the excessive temperature rise area H where excessive temperature rise occurs when the sheet of the maximum width passes through the fixing device, the distance from the lead 44 to the heater 23 is increased by enlarging a portion of the protrusions 30 that are higher than other protrusions. However, when the sheets continuously pass through the fixing device, the temperature rise in the non-sheet passing area is not limited to the case where the sheet P1 having the maximum width passes through the fixing device. Any sheet having a size smaller than the heat generation area 60 of the heater 23 passing through the fixing device may cause a temperature rise in the non-sheet passing area.

[0213] Therefore, if Fig.11 As shown in FIG. 1 , not only the protrusions 30A arranged outside the maximum sheet passing area W1 in the width direction, but also the protrusions 30A arranged inside the maximum sheet passing area W1 in the width direction may be higher than the protrusions 30B arranged in other areas. Specifically, Fig.11 In the example shown, the fixing device 20 includes a protrusion 30A facing the outside of the minimum sheet passing area W2 in the width direction, and the protrusion 30A is higher than the protrusion 30B facing the minimum sheet passing area W2, that is, t6>t5. Since the distance from the heater 23 to the lead 44 facing the outside of the minimum sheet passing area W2 in the width direction is greater than the distance from the heater 23 to the lead 44 facing the minimum sheet passing area W2, the above-mentioned configuration can reduce the temperature increase of the lead 44 facing the non-sheet passing area of ​​the sheet having any size.

[0214] Alternatively, according to Fig.12 The fixing device 20 of the illustrated embodiment includes protrusions 30A2 that face the maximum sheet passing area W1 and each have a height different from that of the protrusions 30A1 facing the outer side in the width direction of the maximum sheet passing area W1. Specifically, as shown in FIG. Fig.12 As shown, the height of the protrusion 30A2 facing the width direction outer side of the maximum sheet passing area W1 and the minimum sheet passing area W2 is t7, which is set lower than the height t8 of the protrusion 30A1 facing the width direction outer side of the maximum sheet passing area W1. Fig.12 The fixing device 20 of the illustrated embodiment includes the highest protrusion 30A1 facing the outer side in the width direction of the maximum sheet passing area W1, the second highest protrusion 30A2 facing the outer side in the width direction of the maximum sheet passing area W1 and the minimum sheet passing area W2, and the lowest protrusion 30B facing the minimum sheet passing area W2, that is, Fig.12 In this example, t8>t7>t5.

[0215] Setting the height t7 of the protrusion 30A2 facing the outer side of the minimum sheet passing area W2 in the width direction and the inner side of the maximum sheet passing area W1 in the width direction to be lower than the height t8 of the protrusion 30A1 facing the outer side of the maximum sheet passing area W1 in the width direction can enhance the flexibility of the layout. Setting the height t7 of the protrusion 30A2 facing the outer side of the minimum sheet passing area W2 in the width direction and the inner side of the maximum sheet passing area W1 in the width direction to be low reduces the effect of preventing heat transfer to the lead 44 to a certain extent. However, as required, the productivity of small-sized sheets (small-sized sheets smaller than the maximum width) when passing through the paper is reduced, and the temperature rise in the non-sheet passing area can be suppressed. Therefore, the temperature rise of the lead 44 in the non-sheet passing area can be controlled within the allowable range.

[0216] In the above embodiment, the protrusion 30A including the protrusions 30A1 and 30A2 only needs to be higher than the protrusion 30B facing the minimum sheet passing area W2. However, the protrusion 30B facing the minimum sheet passing area W2 for comparison is located within the wiring area of ​​the lead 44. Fig.13 The protrusion 32 shown is opposite to the minimum sheet passing area W2 but is not in the wiring area of ​​the lead 44 and therefore is not a subject of height comparison. This is because the protrusion 32 is not a conductor support portion (ie, the protrusion 30 ) that supports the lead 44 .

[0217] In addition, if Fig.14 As shown in FIG. 1 , a protrusion such as the guide 26 protruding from the heater holder 24 is not a subject of comparison in terms of height. This is because the protrusion such as the guide 26 is not a conductor support portion (i.e., the protrusion 30) that supports the lead wire 44. The protrusion that becomes the subject of height comparison is a protrusion provided in an area where the lead wire 44 can exist (i.e., the area J where the temperature sensor 27 exists), which is located in the area J where the temperature sensor 27 exists. Fig.14 The sheets are shown extending in a direction Y (ie, a sheet conveying direction).

[0218] In addition, the protrusion 30 of the support lead 44 does not necessarily face the minimum sheet passing area W2. The protrusion 30 of the support lead 44 may not face the minimum sheet passing area W2. Figure 6 As shown, the protrusion 30 (i.e., the protrusion 30B) located inside the maximum sheet passing area W1 and outside the minimum sheet passing area W2 may not be used as a height comparison object. Therefore, in the present disclosure, the object for comparing heights is not limited to the protrusion facing the minimum sheet passing area W2 and the protrusion facing the outside of the minimum sheet passing area W2 in the width direction. The object for comparing heights may be a protrusion facing a predetermined area other than the minimum sheet passing area W2 and a protrusion facing the outside of the predetermined area in the width direction. That is, the object for comparing heights may be a protrusion 30 facing an arbitrarily defined predetermined area (e.g., the minimum sheet passing area W2 or the maximum sheet passing area W1) and a protrusion 30 facing the outside of the predetermined area in the width direction. It may also be that the height of at least one protrusion 30 facing the outside of the predetermined area in the width direction is higher than the height of other protrusions 30 facing the outside of the predetermined area. Since the protrusion 30 that is higher than the other protrusions 30 supports the lead 44, the distance from the lead 44 to the heater 23 outside the predetermined area along the width direction is greater than the distance from the lead 44 to the predetermined area of ​​the heater 23. Therefore, the temperature rise of the lead 44 facing the outside of the width direction of the predetermined area can be suppressed.

[0219] In the above embodiment, by setting the height of at least one protrusion 30 higher than the other protrusions, the temperature rise of the lead 44 is suppressed. In addition to the above configuration including the protrusion 30 higher than the other protrusions, the present disclosure also includes the following embodiments.

[0220] Different from the above embodiment, according to Fig.15 The fixing device 20 of the illustrated embodiment includes protrusions 30 at intervals d1, and the intervals d1 are smaller than the intervals d2 between other protrusions 30, that is, Fig.15 d1<d2 in the figure. Specifically, the first interval d1 between the protrusions 30 as the first protrusions arranged in the heat generation area 60 of the heater 23 is made smaller than the second interval d2 between the protrusions 30 as the second protrusions facing the maximum sheet passing area W1, outside the width direction of the maximum sheet passing area W1. In this case, the lead 44 between the protrusions 30 separated by the maximum interval (i.e., the interval d2) sags, and the height s2 from the heater support 24 to the lead 44 is reduced. In contrast, the lead 44 between the protrusions 30 separated by a small interval (i.e., the interval d1) is difficult to sag downward, and the height s1 from the heater support 24 to the lead 44 is maintained higher than the height s2. The heights s1, s2, and s3 from the heater support 24 to the lead 44 described below refer to the shortest distance from the lead 44 to the surface of the heater support 24 opposite to the lead 44 (in other words, the surface of the heater support 24 opposite to the surface holding the heater 23). By thus reducing the intervals of the protrusions 30, in the configuration of the protrusions 30 separated by small intervals (i.e., the first interval d1), the height s1 from the heater support 24 to the lead 44 can be maintained higher than the height s2, and the lead 44 is less likely to approach the base 31 of the heater support 24. As a result, when the sheet P1 having the maximum width continuously passes through the fixing device, the lead 44 facing the excessive temperature rise region H in the heater 23 where the temperature rise is likely to occur is less likely to approach the heater 23 than the lead 44 facing the region other than the excessive temperature rise region H, which makes it possible to easily maintain the distance between the heater 23 and the lead 44. Therefore, the above-mentioned structure can reduce the temperature rise of the lead 44 facing the excessive temperature rise region H.

[0221] The protrusions 30 spaced at small intervals are not limited to the protrusions 30 facing the width direction outer side of the maximum sheet passing area W1. Fig.16 As shown, the interval d1 between the protrusions 30 facing the outside in the width direction of the maximum sheet passing area W1 and the interval d3 between the protrusions 30 facing the inside of the maximum sheet passing area W1 and facing the outside in the width direction of the minimum sheet passing area W2 can be set to be narrower than the interval d2 between the protrusions 30 facing other areas (d1, d3<d2).

[0222] By setting the intervals d1 and d3 between the protrusions 30 facing the outer side in the width direction of the minimum sheet passing area W2 to be smaller than the interval d2 between the protrusions 30 facing the minimum sheet passing area W2 (i.e., d1, d3<d2), the heights s1 and s3 of the heater holder 24 from the lead 44 to the outer side in the width direction of the minimum sheet passing area W2 (in other words, facing the area where the protrusions separated by the intervals d1 or d3 are provided) can be kept higher than the height s2 of the heater holder 24 from the lead 44 to the minimum sheet passing area W2 (in other words, facing the area where the protrusions separated by the intervals d2 are provided). The above configuration can cope with the temperature increase in the non-sheet passing area not only when the sheet P1 having the maximum width continuously passes through the fixing device but also when sheets of all sizes pass through the fixing device. That is, the above-mentioned structure can effectively reduce the temperature increase of the lead 44 because the above-mentioned structure can prevent the lead 44 from approaching the heater 23 and the base 31 of the heater bracket 24 in the non-sheet passing area (the area outside the minimum sheet passing area W2) where the temperature increase may occur when a sheet of any size passes through the fixing device.

[0223] In addition, in the case where the temperature rise outside the maximum sheet passing area W1 may be significant, the interval d1 between the protrusions 30 facing the width direction outside of the maximum sheet passing area W1 is set to be smaller than the interval d3 between the protrusions 30 facing the inside of the maximum sheet passing area W1 and facing the width direction outside of the minimum sheet passing area W2, that is, Fig.16 As shown in the figure, d1<d3 can more reliably reduce the temperature rise of the lead 44 provided in the area where the temperature rise is particularly likely to occur (i.e., the area where the protrusions 30 separated by the interval d1 exist). That is, in this embodiment, the closer to the end of the heater 23 in the longitudinal direction where the temperature rise is likely to occur, the smaller the interval between the protrusions 30, that is, d1<d3<d2. As a result, the lead 44 is unlikely to sag downward, and the height from the lead 44 to the heater bracket 24 can be kept high (s1>s3>s2), and the temperature rise of the lead 44 can be suppressed.

[0224] Regarding the size relationship of the intervals between the protrusions 30, the protrusions 30 used as the comparison object are determined based on the same reference as the protrusions 30 of the comparison height. In other words, any one of the intervals between the protrusions 30 facing the width direction outside of the minimum sheet passing area W2 can be smaller than the interval between the protrusions 30 facing the minimum sheet passing area W2. However, the protrusions 30 facing the minimum sheet passing area W2 are set to be within the area where the leads 44 are wired. In addition, the protrusions 30 facing the minimum sheet passing area W2 are set to be arranged in the area where the leads 44 can exist in the sheet passing direction Y (i.e., the sheet conveying direction), that is, the area J where the temperature sensor 27 exists (see Fig.14). The objects for comparing the size relationship of the intervals between the protrusions 30 are not limited to the protrusions facing the minimum sheet passing area W2 and the protrusions facing the outside of the minimum sheet passing area W2 in the width direction. It can also be a protrusion facing a predetermined area other than the minimum sheet passing area W2, and a protrusion facing the outside of the width direction of the predetermined area. The interval between at least two protrusions 30 arranged on the outside of the width direction of the predetermined area can be smaller than the interval between other protrusions 30 outside the predetermined area. In addition to the minimum sheet passing area and the maximum sheet passing area, the above-mentioned predetermined area can also be limited as needed.

[0225] In the above-described embodiment, at least one protrusion 30 is higher than the other protrusions 30, or at least one interval of the protrusion 30 is narrower than the other intervals of the protrusions 30. However, the fixing device may include protrusions 30 that are higher than the other protrusions 30 and spaced at intervals that are narrower than the other intervals of the other protrusions 30. In addition, the number of protrusions 30 supporting the lead 44 is not limited to two or more, and may be one.

[0226] For example, Fig.17 As shown, only one protrusion 30 may be provided, facing the heat generating area 60 of the heater 23 and the outer side in the width direction of the maximum sheet passing area W1. Preferably, the height t of the protrusion 30 is higher than the height z of the position where the lead 44 is connected to the temperature sensor 27 (i.e., at Fig.17 In this case, since the protrusion 30 supports the lead 44 facing the outer side in the width direction of the maximum sheet passing area W1 where a temperature rise may occur, the protrusion 30 can keep the lead 44 away from the heater 23 and the base 31 of the heater support 24 compared with the lead 44 facing the maximum sheet passing area W1. According to the above structure, heat transfer from the area where the temperature of the heater 23 is likely to rise to the lead 44 can be prevented. The position where a protrusion 30 is provided is not limited to the position of the heater support facing the outer side in the width direction of the maximum sheet passing area W1, and can be appropriately selected as long as the position faces the outer side in the width direction of the minimum sheet passing area W2, which is an area where the temperature is likely to rise, corresponding to the size of the frequently used sheets.

[0227] Next, the arrangement of the protrusions 30 and the shape of the protrusions 30 will be described. The arrangement of the protrusions 30 and the shape of the protrusions 30 described below can also be applied to any of the protrusions 30 in the above-described embodiments.

[0228] Fig.18 This is a plan view of the heater support 24 as viewed from the heater 23 side. Fig.18 As shown, the heater 23 includes a plurality of resistance heating elements 56 arranged at intervals in the length direction X (ie, the sheet width direction). In this case, it is preferred that Fig.18At least one protrusion 30 on the right side of the heater 23 is arranged to overlap with the region E between the heater 23 and the resistive heating element 56 in the longitudinal direction X (i.e., the sheet width direction), or is arranged at a position offset from the heater 23. In the above description, "the protrusion 30 overlaps with the region E" means that the protrusion 30 overlaps with the region E in the direction orthogonal to the surface provided with the heater 23 (in other words, in the direction from the heater 23 to the sheet width direction). Fig.18 When the heater 23 is observed in a direction perpendicular to the paper surface), at least a portion of the protrusion 30 overlaps with the area E between the resistive heating element 56.

[0229] As described above, by arranging the protrusion 30 to overlap with the region E between the resistance heating elements 56, the temperature rise of the protrusion 30 can be suppressed. Since the temperature of the region E between the resistance heating elements 56 is less likely to rise than the temperature of the region where the resistance heating elements 56 are located, the temperature rise of the protrusion 30 can be suppressed by arranging the protrusion 30 to overlap with the region E. As a result, the amount of heat transferred from the protrusion 30 to the lead 44 can be reduced, and the temperature rise of the lead 44 can be reduced. In the fixing device including a plurality of temperature sensors, in addition to the right side of the heater 23, the lead 44 is also wired in Fig.18 In this case, the protrusion 30 can be configured to overlap with the area E between the resistive heating elements on the left side of the heater 23 (see Fig.18 double-dotted line in the figure).

[0230] In addition, if Fig.18 As shown, the fixing device 20 includes a plurality of guides 26 which are arranged at intervals in the length direction X (i.e., the sheet width direction) of the heater 23. In this case, it is preferred that at least one protrusion 30 is disposed at a position offset from the guide 26 in the length direction X (i.e., the sheet width direction) of the heater 23. Fig.18 According to the above structure, the heat accumulated in the guide member 26 can be prevented from affecting the protrusion 30, so that the temperature rise of the protrusion 30 can be suppressed, and as a result, the temperature rise of the lead 44 can be suppressed. Fig.18 In the figure, the protrusion 30 ( Fig.18 The heater 23 (as indicated by the two-dot chain line in FIG. 1 ) may also be arranged at a position offset from the guide 26 in the longitudinal direction X (ie, the sheet width direction) of the heater 23.

[0231] In addition, if Fig.19 As shown, the heater 23 is provided with a resistance heating element 56 at the center M of the heater 23 or the clamping portion N in the sheet conveying direction U. In this case, the cross-sectional shape of the protrusion 30 is preferably Fig.19In the shape shown, the central portion 30m in the sheet conveying direction is higher than the two end side portions of the protrusion. In the cross-sectional shape, if the lead 44 is arranged at the central portion 30m of the protrusion 30 in the sheet conveying direction, it is possible to ensure that the lead 44 is at a large distance relative to the heater 23, and it is easy to suppress the temperature rise of the lead 44. In the case where gravity causes the lead 44 to move from the central portion 30m of the protrusion 30 along the sheet conveying direction to one of the two sides of the protrusion 30, the cross-sectional shape of the protrusion 30 having the central portion 30m higher than the two sides of the protrusion 30 along the sheet conveying direction causes the lead 44 to move away from the resistive heating element 56. As a result, in this case, the temperature rise of the lead 44 can also be suppressed by the above-mentioned structure.

[0232] The shape of the protrusion 30 is not limited to Fig.19 The front end surface of the protrusion 30 shown in the figure is a convex curved surface shape that gradually increases toward the central portion 30m in the sheet conveying direction. Fig. 20 As shown, the shape of the protrusion 30 may be a convex step shape in which the front end surface of the central portion 30m and the vicinity thereof in the sheet conveying direction becomes suddenly high.

[0233] like Fig.21 As shown, in the case where the resistance heating element 56 is provided at both end sides relative to the clamping portion N or the center M of the heater 23 in the sheet conveying direction, it is preferred that the center portion 30m of the protrusion 30 in the sheet conveying direction is formed to be lower than the end side portions of the protrusion 30. In this case, since the lead wire 44 moves toward the center portion 30m of the protrusion 30 in the sheet conveying direction due to gravity, the lead wire 44 can be away from the resistance heating element 56, and the temperature rise of the lead wire 44 can be reduced.

[0234] The shape of the protrusion 30 is not limited to Fig.21 The front end surface of the protrusion 30 shown in FIG. 1 is a concave curved surface that gradually decreases toward the center portion 30m in the sheet conveying direction. Fig. 22 As shown, the shape of the protrusion 30 may be a concave step shape in which the front end surface of the central portion 30 m and the vicinity thereof in the sheet conveying direction drops sharply.

[0235] The fixing device according to the above-described embodiment may have the following configuration as an additional modification.

[0236] exist Fig.23 In the example shown, the fixing device 20 includes a low thermal conductor 63 provided on the inner side of the support 25 (i.e., the side facing the lead wire 44). By supporting the heater support 24 by the support 25, deformation of the heater support 24 can be prevented, and a desired shape of the clamping portion N can be formed. Fig.23As shown, the U-shaped support 25 can ensure a large cross-sectional inertia (ie, resistance to bending force), and can achieve miniaturization while ensuring rigidity. The U-shaped cross section can prevent the support 25 from protruding from the heater bracket 24 and interfering with the fixing belt 21.

[0237] However, heat is transferred from the heater 23 to the heater holder 24 and the support 25 in contact with the heater holder 24, thereby increasing the temperature of the support 25. In particular, since the metal support 25 has good thermal conductivity, the temperature of the support 25 is easily increased. Therefore, it is preferred that the lead 44 does not contact the support 25, and the temperature increase of the lead 44 is reduced.

[0238] Therefore, if Fig.23 As shown, a low thermal conductor 63 having a lower thermal conductivity than that of the support 25 is arranged between the inner surface of the support 25 and the lead 44. According to the above structure, it is possible to prevent the lead 44 from directly contacting the support 25. Even if the lead 44 contacts the low thermal conductor 63, the heat transferred from the low thermal conductor 63 to the lead 44 is less than the heat transferred when the lead 44 contacts the support 25 directly. Therefore, the temperature rise of the lead 44 can be suppressed. The low thermal conductor 63 can be fixed to the inner surface of the support 25 by a screw or a snap mechanism. Alternatively, the low thermal conductor 63 can be arranged on the temperature sensor holding component or the belt holding component described later. Figures 19 to 23 In the illustrated construction, the heater support 24 and the protrusion 30 are integrally formed as one component. Figures 19 to 23 In addition to the illustrated configuration, in other exemplary configurations, the heater support 24 and the protrusion 30 may also be integrally formed as one component.

[0239] In order to suppress the temperature rise of the support 25 itself, Fig.24 As shown in FIG. 2 , a plurality of recesses 250 may be provided on the side of the support 25 opposite to the heater support 24. Since the plurality of recesses 250 reduce the contact area of ​​the support 25 with respect to the heater support 24, the heat transfer from the heater support 24 to the support 25 is reduced, thereby reducing the temperature increase of the lead 44 caused by the heat transferred from the support 25. In addition, the intervals of the recesses 250 of the support 25 are not limited to the same intervals. For example, Fig.24 As shown, in the area where the temperature of the heater 23 easily rises, that is, the area outside the width direction of the minimum sheet passing area W2 in the heating area 60, the interval g1 between the recesses 250 can be smaller than the interval g2 between the recesses 250 in the minimum sheet passing area W2, that is, g1<g2.

[0240] The above-described embodiments are illustrative and do not limit the present disclosure. It is therefore to be understood that many additional modifications and variations of the present disclosure besides those specifically described herein are possible within the scope of the appended claims.

[0241] Thermistors are examples of temperature sensors 27 used in the fixing device. Generally, there are two types of thermistors. Fig.25 As shown, one type of thermistor 39 includes leads 44 connected to both sides of the thermistor 39 . Fig.26 Another type of thermistor 39 shown includes a lead 44 connected to one side of the thermistor 39. The fixing device according to the above embodiment can adopt any type of thermistor. Fig.25 As shown, a thermistor 39 with leads 44 installed on both sides of the thermistor 39 is shown. Fig.26 Another type of thermistor 39 having a lead 44 mounted on one side of the thermistor 39 in the sheet conveying direction U is shown to be smaller, that is, i1<i2. Therefore, the use of one type of thermistor 39 enables the fixing device to be miniaturized in the sheet conveying direction U. Fig.25 As shown in the figure, one of the leads 44 mounted on both sides of the thermistor 39 is bent and routed, so that the leads 44 can be concentrated on one side of the thermistor 39. According to the structure of the embodiment described above, the temperature rise of the leads 44 can be suppressed, so as the leads 44, a lead with low heat resistance temperature and excellent flexibility can be used, and the layout of the bent routing of the leads 44 becomes easy.

[0242] The imaging device to which the embodiments of the present disclosure are applicable is not limited to a central reference conveying system in which sheets of various sizes are conveyed so that the sheets of various sizes are conveyed with the center in the width direction as the reference. The embodiments of the present disclosure may also be applicable to an imaging device of an end conveying reference system in which sheets of various sizes are conveyed so that the sheets of various sizes are conveyed with one end in the width direction as the reference. Fig. 27 As shown, the maximum sheet passing area W1 of the heater of the end conveyance reference system is an area having a maximum sheet width W1 or a length of W1+5 mm from the conveyance reference position r for conveying the sheets P1 and P2, and the minimum sheet passing area W2 is an area having a minimum sheet width W2 or a length of W2+5 mm from the conveyance reference position r. In the image forming apparatus using the end conveyance reference system, by providing the protrusion 30 in the area facing the width direction outside of the minimum sheet passing area W2 and in the heat generating area 60 of the heater 23, a large distance from the heater 23 to the lead 44 can be ensured, and similarly to the above-mentioned embodiment, the temperature rise of the lead 44 can be reduced.

[0243] Fig.28 is a schematic diagram of a supporting structure for supporting a lead wire 44 connected to a temperature sensor 27 in a fixing device according to the present embodiment, which is different from Figure 6 The embodiment shown.

[0244] like Fig.28 As shown, the temperature sensor 27 is connected to one end of a lead wire 44 which is a conductor having flexibility. The other end of the lead wire 44 is connected to a controller provided in the main body of the imaging device. The lead wire 44 includes a wire and an insulator covering the wire to ensure insulation and heat resistance. The first surface 240 (on the opposite side of the second surface 241 of the heater support 24) of the heater support 24 is opposite to the second surface 241 of the heater support 23. Fig.28 The sensor holder 50 is provided as a temperature sensor holding member for holding the temperature sensor 27. The sensor holder 50 includes a main body 50a provided on the heater holder 24 and a spring 50b as an energizing member provided on the main body 50a. The spring 50b presses the temperature sensor 27 against the heater 23, holds the temperature sensor 27, and makes the temperature sensor 27 contact with the heater 23.

[0245] The lead wire 44 is provided on the side of the support of the sensor holder 50 to avoid the direct influence of the heat of the heater 23, sandwiching the heater holder 24 and the sensor holder 50, and arranged on the opposite side of the heater 23. That is, the lead wire 44 is provided on the first surface 510 (i.e., Fig.28 The first surface 510 is opposite to the second surface 520 of the sensor holder 50, and the second surface 520 faces the heater 23. On the first surface 510 of the sensor holder 50 opposite to the lead 44, a plurality of protrusions 30 are provided as conductor support portions for supporting the lead 44.

[0246] The plurality of protrusions 30 protrude from the main body 50a of the sensor holder 50 in a direction away from the heater 23. The plurality of protrusions 30 are arranged at intervals in the longitudinal direction X of the heater 23.

[0247] The front end of each protrusion 30 supports the lead 44, and the lead 44 is separated from the main body 50a of the sensor bracket 50 provided with the protrusion 30 by a gap and is configured to be non-contact. As a result, the lead 44 does not contact the main body 50a. That is, the sensor bracket 50 has a main body 50a, and the main body 50a has a first surface 510 and a second surface 520 on the opposite side of the first surface 510. The second surface 520 is opposite to the heater 23 across the heater bracket 24. On the first surface 510, a plurality of protrusions 30 are provided. As described above, the plurality of protrusions 30 supporting the lead 44 avoid contact between the lead 44 and the main body 50a, and reduce the contact area of ​​the lead 44 relative to the sensor bracket 50. The lead 44, which has a lower rigidity than a metal plate, a jumper wire, etc., requires a component for supporting the lead 44 to keep the lead 44 at a position away from the sensor bracket 50. Therefore, the sensor bracket 50 of this embodiment can reduce the contact area of ​​the lead 44 with respect to the sensor bracket 50 by providing a plurality of protrusions 30 supporting the lead 44, and can prevent heat transfer from the heater 23, the heater bracket 24 and the sensor bracket 50 to the lead 44.

[0248] In addition, since the protrusion 30 is not provided on the heater holder 24 that is in direct contact with the heater 23 and the fixing belt 21, but is provided on the sensor holder 50 that is not in direct contact with the heater 23 and the fixing belt 21, the above-mentioned configuration can reduce the temperature increase of the protrusion 30. Since the temperature of the sensor holder 50 is less likely to rise than that of the heater holder 24, providing the protrusion 30 on the sensor holder 50 can effectively reduce the temperature increase of the protrusion 30. Since the sensor holder 50 is a component separate from the heater holder 24, a temperature difference is generated between the heater holder 24 and the sensor holder 50 due to contact heat resistance, which further prevents the temperature increase of the protrusion 30. Since the above-mentioned protrusion 30 of the present embodiment is not provided on the heater holder 24, but is provided on the sensor holder 50 that is a component separate from the heater holder 24 between the heater holder 24 and the lead wire 44, the temperature increase of the protrusion 30 is effectively reduced, and the temperature increase of the lead wire 44 supported by the protrusion 30 is also effectively reduced.

[0249] The lead wire 44 may not be in contact with the front end of the protrusion 30. That is, the so-called "the protrusion 30 supports the lead wire 44" means that the lead wire 44 is supported so that it does not contact the main body 50a of the sensor holder 50, and includes not only the protrusion 30 and the lead wire 44 being in contact, but also the protrusion that is not always in contact with the lead wire 44. For example, Fig.30 The protrusion 30A2 shown does not actually contact the lead 44. However, when the lead 44 approaches the main body 50a, it is supported to avoid contact with the main body 50a. In the present invention, the protrusion 30 supporting the lead 44 includes the protrusion 30A2.

[0250] exist Fig.28 Among the plurality of protrusions 30, the end portion in the longitudinal direction of the sensor holder 50, that is, the end portion in the longitudinal direction of the heater 23 ( Fig.28 The protrusion 30A is set higher than the other protrusions 30B in the direction protruding from the sensor bracket 50 (i.e., the main body 50a). Fig.28 The protrusion 30A, which is higher than the other protrusions 30B, is provided corresponding to a portion of the heater 23 where the temperature of the heater 23 is higher than the temperature of the other portions of the heater 23 to prevent the heat of the heater 23 from affecting the lead 44 .

[0251] In order to overcome the above disadvantages, the fixing device 20 according to the embodiment of the present disclosure includes the following Fig.28 The protrusion 30A and the protrusion 30B shown in the figure. The protrusion 30A is arranged on the inner side of the heating area 60 of the heater 23 in the width direction and on the outer side of the maximum sheet passing area W1 in the width direction, and is opposite to the excessive temperature rise area H. The protrusion 30A is higher than the protrusion 30B facing the area outside the area H, that is, Fig.28 As a result, the distance from the lead wire 44 to the excessive temperature rise region H of the heater 23 is greater than the distance from the lead wire 44 to the region other than the excessive temperature rise region H of the heater 23 .

[0252] In the above-described structure, heat is hardly transferred from the heater 23 to the lead wire 44. Even if the sheets P1 each having the maximum width continuously pass through the fixing device and cause excessive temperature rise in the excessive temperature rise region H of the heater 23, the above-described configuration can reduce the temperature rise of the lead wire 44, which can prevent deterioration and damage of the lead wire 44. The above-described configuration capable of preventing deterioration and damage of the lead wire 44 enables continuous printing of the sheets P1 having the maximum width without reducing productivity.

[0253] The position of the protrusion 30A having a height higher than that of the protrusion 30B is not limited to the position of the protrusion 30A having a height higher than that of the protrusion 30B. Fig.28 The position opposite to the excessive temperature rise region H shown may be a position of the sensor holder 50 opposite to the outer side of the excessive temperature rise region H of the heater 23 in the longitudinal direction X.

[0254] For example, Fig.29 As shown, in the sensor holder 50, protrusions 30A higher than the protrusions 30B may be arranged at positions corresponding to the outer sides of both ends in the width direction of the excessive temperature rise region H. Fig.29 The structure shown can make the distance from the lead 44 to the excessive temperature rise area H of the heater 23 larger than the distance from the lead 44 to other areas of the heater 23, thereby suppressing the temperature rise of the lead 44. Fig.29The protrusion 30A shown is not opposite to the excessive temperature rise area H, so according to the above structure, the temperature rise of the protrusion 30A itself can be suppressed. By suppressing the temperature rise of the protrusion 30A itself, the heat transferred from the protrusion 30A to the lead 44 can be reduced. As a result, according to the above structure, the temperature rise of the lead 44 can be effectively suppressed. By effectively suppressing the temperature rise of the lead 44, an inexpensive material (a material with not too high heat resistance) can be selected as the material of the lead 44 or the insulator covering the lead 44, thereby achieving cost reduction. On the other hand, Fig.28 The fixing device 20 shown in the figure has the protrusion 30A opposite to the excessive temperature rise area H, and does not have the protrusion 30A provided at the end of the sensor holder 50 corresponding to the outer side of the excessive temperature rise area H in the longitudinal direction of the sensor holder 50. Fig.28 In the structure shown, the space for positioning the protrusion 30A at the end of the sensor holder 50 can be omitted, which has the advantage of being able to reduce the dimension of the sensor holder 50 in the longitudinal direction.

[0255] In addition, if Fig.30 As shown, in the protrusion 30A which is higher than the protrusion 30B, the protrusion 30A1 from the right side of the overheating region H to the outside is higher than the protrusion 30A2 from the left side of the overheating region H to the inside, that is, Fig.30 , t3>t4. In this example, the lead 44 is mainly supported by the high protrusion 30A1. The high protrusion 30A1 toward the outside in the width direction from the heat generating area 60 is less susceptible to the heat of the heater 23 than the protrusion 30A2 toward the heat generating area 60. Since the amount of heat transferred from the high protrusion 30A1 to the lead 44 is less than the amount of heat transferred from the protrusion 30A2 to the lead 44, the above structure can effectively suppress the temperature rise of the lead 44.

[0256] On the contrary, Fig.31 As shown, in the protrusion 30A which is higher than the protrusion 30B, the protrusion 30A2 from the left side of the overheating region H to the inside is higher than the protrusion 30A1 from the right side of the overheating region H to the outside, that is, Fig.31 , t3<t4. Fig.31 The structure shown can reduce the height of the protrusion 30A1 arranged at the end portion in the longitudinal direction of the sensor holder 50, thereby increasing the degree of freedom in designing the wiring of the lead wire 44.

[0257] Next, the following describes Fig.32 The embodiment shown in Fig.32In the illustrated embodiment, the protrusion 30A1 provided at the end portion of the sensor holder 50 opposite to the outer side of the excessive temperature rise region H in the length direction of the sensor holder 50 is closer to the edge portion ( 620 ) of the roller portion 62 (the portion including the elastic layer) of the pressure roller 22 in the length direction. Fig.10 According to the above structure, since there is the protrusion 30A1 opposite to the outside of the excessive temperature rise area H and the outside of the roller portion 62 of the pressure roller 22 in the longitudinal direction, it is possible to prevent heat from being transferred from the pressure roller 22 to the protrusion 30A1 opposite to the outside of the excessive temperature rise area H via the heater holder 24 and the sensor holder 50, and the temperature rise of the protrusion 30A1 can be suppressed. By suppressing the temperature rise of the protrusion 30A1, the heat transferred from the protrusion 30A1 to the lead 44 can be suppressed. As a result, according to the above structure, the temperature rise of the lead 44 can be effectively suppressed.

[0258] In addition, if Fig.32 As shown in FIG. 1 , when a heat spreader 28 as a heat conduction auxiliary member is provided between the heater 23 and the heater support 24 of the fixing device 20, it is preferable to suppress the influence of heat transferred from the heat spreader 28 to the protrusion 30A1. The heat spreader 28 is made of a material having a higher thermal conductivity than that of the heater support 24, such as copper, aluminum, or silver. The heat spreader 28 moves the heat from the heater 23 along the length direction of the fixing belt 21 to uniformly heat the fixing belt 21. Fig.32 As shown, in the longitudinal direction of the sensor bracket 50, the protrusion 30A1 at the end of the sensor bracket 50 opposite to the outer side of the excessive temperature rise region H is closer to the end 280 of the heat spreader 28 in the longitudinal direction of the sensor bracket 50 ( Fig.32 The right side of the sensor holder 50 in the middle) can suppress heat transfer from the heat spreader 28 to the protrusion 30A1 facing the outside of the excessive temperature rise region H, and can effectively suppress the temperature rise of the protrusion 30A1.

[0259] In the above-described embodiments, in the excessive temperature rise area H where excessive temperature rise occurs when the sheet of the maximum width passes through the fixing device, the distance from the lead 44 to the heater 23 is made larger by one or some protrusions 30 that are higher than other protrusions. However, when the sheets continuously pass through the fixing device, the temperature rise in the non-sheet passing area is not limited to the case where the sheet P1 having the maximum width passes through the fixing device. The passage of a sheet having any size smaller than the heat generation area 60 of the heater 23 through the fixing device may cause a temperature rise in the non-sheet passing area of ​​the heater 23.

[0260] Therefore, if Fig.33As shown in FIG. 1 , not only the protrusion 30A facing the outer side in the width direction of the maximum sheet passing area W1 but also the protrusion 30A facing the inner side in the width direction of the maximum sheet passing area W1 may be higher than the protrusion 30B facing other areas. Specifically, the fixing device 20 includes the protrusion 30A facing the outer side in the width direction of the minimum sheet passing area W2, which is higher than the protrusion 30B facing the minimum sheet passing area W2, that is, Fig.33 Since the distance from the heater 23 to the lead 44 facing the outer side in the width direction of the minimum sheet passing area W2 is greater than the distance from the heater 23 to the lead 44 facing the minimum sheet passing area W2, the above-mentioned configuration can reduce the temperature rise of the lead 44 facing the non-sheet passing area of ​​the sheet having any size.

[0261] Alternatively, according to Fig.34 The fixing device 20 of the illustrated embodiment includes protrusions 30A2 that face the maximum sheet passing area W1 and each have a height different from that of the protrusions 30A1 facing the outer side in the width direction of the maximum sheet passing area W1. Specifically, as shown in FIG. Fig.34 As shown, the height t7 of the protrusion 30A2 facing the width direction outer side of the maximum sheet passing area W1 and the minimum sheet passing area W2 is set lower than the height t8 of the protrusion 30A1 facing the width direction outer side of the maximum sheet passing area W1. Fig.34 The fixing device 20 of the illustrated embodiment includes the highest protrusion 30A1 facing the outer side in the width direction of the maximum sheet passing area W1, the second highest protrusion 30A2 facing the outer side in the width direction of the maximum sheet passing area W1 and the minimum sheet passing area W2, and the lowest protrusion 30B facing the minimum sheet passing area W2, that is, Fig.12 In this example, t8>t7>t5.

[0262] Setting the height t7 of the protrusion 30A2 facing the outer side in the width direction of the minimum sheet passing area W2 and the inner side in the width direction of the maximum sheet passing area W1 to be lower than the height t8 of the protrusion 30A1 facing the outer side in the width direction of the maximum sheet passing area W1 can enhance the flexibility of the layout. Setting the height t7 of the protrusion 30A2 facing the outer side in the width direction of the minimum sheet passing area W2 and the inner side in the width direction of the maximum sheet passing area W1 to be low reduces the effect of preventing heat transfer to the lead 44 to a certain extent. However, when the productivity is reduced when a small-sized sheet having a smaller size than the maximum sheet width is passed through the fixing device as needed, the temperature rise in the non-sheet passing area can be suppressed, and therefore, the temperature rise of the lead 44 in the non-sheet passing area can be controlled within the allowable range.

[0263] In the above embodiment, the protrusion 30A including the protrusions 30A1 and 30A2 may be at least higher than the protrusion 30B facing the minimum sheet passing area W2. However, the protrusion 30B facing the minimum sheet passing area W2 compared with the protrusion 30A is located within the wiring area of ​​the lead 44.

[0264] Fig.35 This is a cross-sectional view of the fixing device as viewed from a direction orthogonal to a sheet passing direction U which is a sheet conveying direction. Fig.35 The protrusion 33 shown is not comparable to the protrusion 30A in terms of height because the protrusion 33 is outside the area where the lead 44 is routed and is not a conductor support member (i.e., each of the protrusions 30) that supports the lead 44. Fig.35 The projections in the region where the lead wires 44 in the sheet passing direction U (ie, the sheet conveying direction) can exist are shown.

[0265] In addition, the protrusion 30 of the support lead 44 does not necessarily face the minimum sheet passing area W2. The protrusion 30 of the support lead 44 may not face the minimum sheet passing area W2. Fig.28 As shown, a protrusion that does not face the minimum sheet passing area W2 can be compared with a protrusion 30 (i.e., protrusion 30B) that faces the maximum sheet passing area W1 and is located outside the minimum sheet passing area W2 in the width direction. In the present disclosure, the protrusions of comparative height are not limited to the protrusions facing the minimum sheet passing area W2 and the protrusions facing the outside of the minimum sheet passing area W2 in the width direction. The protrusions of comparative height may be protrusions facing a predetermined area other than the minimum sheet passing area W2 and protrusions facing the outside of the predetermined area in the width direction. That is, the protrusions of comparative height may be protrusions 30 facing a predetermined area arbitrarily defined from, for example, the minimum sheet passing area W2 or the maximum sheet passing area W1, and protrusions 30 facing the outside of the predetermined area in the width direction. At least one protrusion 30 facing the outside of the predetermined area in the width direction may be higher than another protrusion 30 facing the predetermined area. Since the height of the protrusion 30 is higher than the height of other protrusions 30, the protrusion 30 makes the distance from the heater 23 to the lead 44 opposite to the outer side in the width direction of the predetermined area larger than the distance from the heater 23 to the lead 44 opposite to the predetermined area, thereby supporting the lead 44. Therefore, the temperature rise of the lead 44 opposite to the outer side in the width direction of the predetermined area can be suppressed.

[0266] In the above embodiment, by setting the height of at least one protrusion 30 higher than the other protrusions, the temperature rise of the lead 44 is suppressed. In addition to the above configuration including the protrusion 30 higher than the other protrusions, the present disclosure includes the following embodiments.

[0267] Different from the above embodiment, according to Fig.36 The fixing device 20 of the illustrated embodiment includes protrusions 30 at intervals d1, and the intervals d1 are smaller than the intervals d2 between other protrusions 30, that is, Fig.36 d1<d2 in the figure. Specifically, the interval d1, which is the first interval between the protrusions 30, which are the first protrusions facing the outside in the width direction of the maximum sheet passing area W1 and arranged in the heat generation area 60 of the heater 23, is smaller than the interval d2, which is the second interval between the protrusions 30, which are the second protrusions facing the maximum sheet passing area W1. In this case, since the lead 44 between the protrusions 30 separated by a larger interval (i.e., the interval d2) droops downward, the height s2 from the sensor holder 50 to the lead 44 becomes smaller. On the other hand, the lead 44 between the protrusions 30 separated by a smaller interval (i.e., the interval d1) is less likely to droop downward, and therefore, the height s1 from the sensor holder 50 to the lead 44 is maintained higher than the height s2. The heights s1, s2, and s3 from the sensor holder 50 to the lead 44 described below refer to the shortest distance from the lead 44 to the surface opposite to the lead 44, i.e., the surface of the main body 50a of the sensor holder 50. In this way, by reducing the intervals of the protrusions 30, the height s1 from the sensor holder 50 to the lead 44 in the area where the protrusions 30 are arranged at small intervals (i.e., the first interval d1) can be maintained higher than the height s2, so that the lead 44 is difficult to approach the main body 50a of the sensor holder 50. As a result, the lead 44 facing the excessive temperature rise area H is less likely to approach the heater 23 than the lead 44 facing the area other than the excessive temperature rise area H, which makes it easy to maintain the distance between the heater 23 and the lead 44. Therefore, according to the above-mentioned structure, the temperature rise of the lead 44 opposite to the excessive temperature rise area H can be suppressed.

[0268] The protrusions 30 separated at small intervals are not limited to the protrusions 30 facing the width direction outer side of the maximum sheet passing area W1. Fig.37 As shown, the interval d1 between the protrusions 30 facing the outside in the width direction of the maximum sheet passing area W1 and the interval d3 between the protrusions 30 facing the outside in the width direction of the maximum sheet passing area W1 and the minimum sheet passing area W2 can be set to be narrower than the interval d2 between the protrusions 30 facing other areas (d1, d3<d2).

[0269] By setting the intervals d1 and d3 between the protrusions 30 outside the minimum sheet passing area W2 in the width direction to be smaller than the interval d2 between the protrusions 30 inside the minimum sheet passing area W2 in the width direction (i.e., d1, d3<d2), the heights s1 and s3 from the lead 44 to the sensor holder 50 facing outside the minimum sheet passing area W2 in the width direction (in other words, the area of ​​the sensor holder 50 provided with the protrusions separated by the interval d1 or d3) can be kept higher than the height s2 from the lead 44 to the sensor holder 50 facing the minimum sheet passing area W2 (in other words, the area of ​​the sensor holder 50 provided with the protrusions separated by the interval d2). The above configuration can cope with the temperature increase in the non-sheet passing area not only when the sheet P1 having the maximum sheet width passes through the fixing device but also when sheets of all sizes pass through the fixing device. That is, in the non-sheet passing area (the area located outside the minimum sheet passing area W2 in the width direction) where temperature rise may occur when a sheet of any size passes through the fixing device, the above-mentioned structure can prevent the lead 44 from approaching the heater 23 and the main body 50a of the sensor bracket 50, thereby effectively reducing the temperature rise of the lead 44.

[0270] In addition, in the case where the temperature rise outside the maximum sheet passing area W1 in the width direction may be significant, the interval d1 between the protrusions 30 facing outside the maximum sheet passing area W1 in the width direction is set to be smaller than the interval d3 between the protrusions 30 facing inside the maximum sheet passing area W1 and outside the width direction of the minimum sheet passing area W2, that is, Fig.37 As shown, d1<d3, the temperature rise of the lead wire 44 provided in the area where the temperature rise is particularly likely to occur (i.e., the area where the protrusions 30 separated by the interval d1) can be more reliably prevented. That is, in this embodiment, the closer to the end of the heater 23 in the longitudinal direction where the temperature rise is likely to occur, the smaller the interval between the protrusions 30, that is, d1<d3<d2. As a result, the lead wire 44 is unlikely to sag downward, and the height from the lead wire 44 to the sensor holder 50 can be kept high (s1>s3>s2), and the temperature rise of the lead wire 44 can be prevented.

[0271] In addition, regarding the size relationship of the intervals between the protrusions 30, the protrusions 30 used as the comparison object are determined based on the same reference as the protrusions 30 of the comparison height. In other words, any of the intervals between the protrusions 30 facing the outside of the minimum sheet passing area W2 in the width direction is smaller than the intervals between the protrusions 30 facing the inside of the minimum sheet passing area W2. However, the protrusions 30 facing the inside of the minimum sheet passing area W2 are within the area where the lead 44 is wired. In addition, the protrusions 30 facing the inside of the minimum sheet passing area W2 are located in the area where the lead 44 can exist in the passing direction U (i.e., the sheet conveying direction) (refer to Fig.14). The size relationship of the intervals between the comparison protrusions 30 is not limited to the intervals between the protrusions facing the minimum sheet passing area W2 and the intervals between the protrusions facing the outside in the width direction of the minimum sheet passing area W2. The intervals between the comparison protrusions can be the intervals between the protrusions facing the predetermined area other than the minimum sheet passing area W2, and the intervals between the protrusions facing the outside in the width direction of the predetermined area. In addition, the intervals between at least two protrusions 30 facing the outside of the predetermined area may be smaller than the intervals between other protrusions 30 facing the predetermined area. The "predetermined area" mentioned here includes the minimum sheet passing area or the maximum sheet passing area, and in addition, it may also include an area arbitrarily defined as needed.

[0272] In the above-described embodiment, at least one protrusion 30 is higher than the other protrusions 30, or the intervals between at least a part of the protrusions 30 are narrow. However, the fixing device may include protrusions 30 that are higher than the other protrusions 30 and have narrower intervals than the other protrusions 30. In addition, the number of protrusions 30 supporting the lead 44 is not limited to two or more, and may be one.

[0273] For example, Fig.38 As shown, only one protrusion 30 may face the outside of the heating area 60 of the heater 23 and the maximum sheet passing area W1 in the width direction. It is preferred that the height t of the protrusion 30 is higher than the height z of the position where the lead 44 is connected to the temperature sensor 27 (i.e., at Fig.17 In this case, since the protrusion 30 supports the lead 44 facing the outer side in the width direction of the maximum sheet passing area W1 where a temperature rise may occur, the protrusion 30 can keep the lead 44 away from the heater 23 and the main body 50a of the sensor holder 50 compared to the lead 44 facing the maximum sheet passing area W1. According to the above structure, heat transfer from the area where the temperature of the heater 23 is likely to rise to the lead 44 can be prevented. The position where a protrusion 30 is provided is not limited to the position of the heater holder facing the outer side in the width direction of the maximum sheet passing area W1, and can be appropriately selected as long as the position faces the outer side in the width direction of the minimum sheet passing area W2, which is an area where the temperature is likely to rise, corresponding to the size of the frequently used sheets.

[0274] Next, the arrangement of the protrusions 30 and the shape of the protrusions 30 will be described. The arrangement of the protrusions 30 and the shape of the protrusions 30 described below can also be applied to any of the protrusions 30 in the above-described embodiments.

[0275] Fig.39 2 is a top view of the sensor bracket 50 as viewed from the heater 23 side. Fig.39As shown, the heater 23 includes a plurality of resistance heating elements 56 arranged at intervals in the length direction X (ie, the sheet width direction). Fig.18 At least one protrusion 30 facing the right side of the heater 23 is arranged to overlap with the region E between the resistive heating element 56 in the longitudinal direction X (i.e., the sheet width direction) of the heater 23, or is arranged at a position offset from the resistive heating element 56. In the above, "the protrusion 30 overlaps with the region E" means that the protrusion 30 overlaps with the region E from the direction orthogonal to the surface where the resistive heating element 56 is arranged (in other words, from the direction perpendicular to the surface where the resistive heating element 56 is arranged). Fig.39 When the heater 23 is observed in a direction perpendicular to the paper surface), at least a portion of the protrusion 30 overlaps with the area E between the resistive heating element 56.

[0276] As described above, by arranging the protrusion 30 to overlap with the region E between the resistance heating elements 56, the temperature rise of the protrusion 30 can be suppressed. Since the temperature of the region E between the resistance heating elements 56 is less likely to rise than the temperature of the region where the resistance heating elements 56 are located, the temperature rise of the protrusion 30 can be suppressed by arranging the protrusion 30 to overlap with the region E. As a result, the amount of heat transferred from the protrusion 30 to the lead 44 can be reduced, and the temperature rise of the lead 44 can be reduced. In the fixing device including a plurality of temperature sensors, in addition to the lead 44 facing the right portion of the heater 23, a temperature sensor facing the right portion of the heater 23 is also arranged. Fig.39 In this case, the protrusion 30 can be configured to overlap with the area E between the resistive heating elements on the left side of the heater 23 (see Fig.39 double-dotted line in the figure).

[0277] In addition, if Fig.39 As shown, the fixing device 20 includes a plurality of guides 26 arranged at intervals in the length direction X (i.e., the sheet width direction) of the heater 23. In this case, it is preferred that at least one protrusion 30 is provided at a position offset from the guide 26 in the length direction X (i.e., the sheet width direction) of the heater 23. Fig.39 According to the above structure, the heat accumulated in the guide 26 can be prevented from affecting the protrusion 30, so that the temperature rise of the protrusion 30 can be suppressed, and as a result, the temperature rise of the lead 44 can be suppressed. Fig.39 In the embodiment, at least one protrusion 30 ( 20 ) opposite to the left portion of the heater 23 may be arranged at a position offset from the guide 26 in the longitudinal direction X (sheet width direction) of the heater 23. Fig.39 Indicated by double-dotted lines).

[0278] In addition, if Fig.40As shown, a resistance heating element 56 is provided at the center M of the heater 23 or at the center M of the clamping portion N in the sheet conveying direction U. In this case, it is preferred to include a Fig.40 The protrusion of the cross-sectional shape shown, that is, the protrusion 30 has a center 30m higher than the parts on both sides in the sheet conveying direction. In the cross-sectional shape, if the lead 44 is arranged at the center 30m of the protrusion 30 along the sheet conveying direction, it is possible to ensure a large distance between the lead 44 and the heater 23, which easily reduces the temperature rise of the lead 44. In the case where gravity moves the lead 44 from the center 30m of the protrusion 30 along the sheet conveying direction to one of the two sides of the protrusion 30, the cross-sectional shape of the protrusion 30 having the center 30m higher than the two sides of the protrusion 30 along the sheet conveying direction causes the lead 44 to move away from the resistive heating element 56. As a result, in this case, the temperature rise of the lead 44 can also be suppressed by the above-mentioned structure.

[0279] The shape of the protrusion 30 is not limited to Fig.40 The front end surface of the protrusion 30 shown in FIG. 1 is a convex curved surface that gradually rises toward the center 30 m in the sheet conveying direction. Fig.41 As shown, the shape of the protrusion 30 may be a convex step shape in which the front end surface of the center 30 m and the vicinity thereof in the sheet conveying direction rises sharply.

[0280] like Fig.42 As shown, in the case where the resistance heating element 56 is provided at both end sides of the heater 23 relative to the center M of the heater 23 or the center M of the clamping portion N in the sheet conveying direction, it is preferred that the center 30m of the protrusion 30 in the sheet conveying direction is formed to be lower than the end sides of the protrusion 30. In this case, since the lead wire 44 moves toward the center 30m of the protrusion 30 in the sheet conveying direction due to gravity, the lead wire 44 can be away from the resistance heating element 56, which can reduce the temperature increase of the lead wire 44.

[0281] The shape of the protrusion 30 is not limited to Fig.42 The front end surface of the protrusion 30 shown in the figure is a concave curved surface shape which gradually decreases toward the center 30m in the sheet conveying direction. Fig.43 As shown, the shape of the protrusion 30 may be a concave step shape in which the front end surface of the center 30 m and its vicinity in the sheet conveying direction drops sharply.

[0282] The fixing device according to the above-described embodiment may have the following configuration as an additional modification.

[0283] exist Fig.44In the example shown, the fixing device 20 includes a low-heat conductor 63 provided on the inner side of the support 25 (i.e., the side facing the lead 44). By supporting the heater support 24 by the support 25, deformation of the heater support 24 can be prevented, and a desired shape of the clamping portion N can be formed. Fig.44 As shown, the U-shaped support 25 can ensure a large cross-sectional inertia (ie, resistance to bending force), and can achieve miniaturization while ensuring rigidity. The U-shaped cross section can prevent the support 25 from protruding from the heater bracket 24 and interfering with the fixing belt 21.

[0284] However, heat is transferred from the heater 23 to the heater holder 24 and the support 25 in contact with the heater holder 24, thereby increasing the temperature of the support 25. In particular, since the metal support 25 has good thermal conductivity, the temperature of the support 25 is easily increased. Therefore, it is preferred that the lead 44 does not contact the support 25, and the temperature increase of the lead 44 is reduced.

[0285] Therefore, if Fig.44 As shown, a low thermal conductor 63 having a lower thermal conductivity than the support 25 is arranged between the inner surface of the support 25 and the lead 44. According to the above structure, it is possible to prevent the lead 44 from directly contacting the support 25. Even if the lead 44 contacts the low thermal conductor 63, the amount of heat transferred from the low thermal conductor 63 to the lead 44 is less than the amount of heat transferred when the lead 44 contacts the support 25 directly. Therefore, the temperature rise of the lead 44 can be suppressed. The low thermal conductor 63 can be fixed to the inner surface of the support 25 by a screw or a snap mechanism. Alternatively, the low thermal conductor 63 can be arranged on the temperature sensor bracket 50 or the belt holder described later.

[0286] In the above embodiment, the protrusion 30 supporting the lead wire 44 is provided on the sensor holder 50 holding the temperature sensor 27 facing the minimum sheet passing area W2, but the sensor holder 50 on which the protrusion 30 is provided is not limited thereto. Fig.45 As shown, the protrusion 30 may be provided on a sensor holder 50B that holds the temperature sensor 27B facing the widthwise outer side of the maximum sheet passing region W1 to support the lead wire 44 extending from the temperature sensor 27A facing the minimum sheet passing region W2 .

[0287] Next, describe Fig.46 The embodiment shown. Fig.46 In the embodiment, the protrusion 30 supporting the lead wire 44 is provided on a flange 70 (i.e., a belt holder) which holds one of the two ends in the length direction of the fixing belt 21. The flange 70 includes a holding portion 70a and an adjuster 70b. The holding portion 70a is a C-shaped portion or a cylindrical portion inserted into the inner side of the loop of the fixing belt 21. The adjuster 70b adjusts the fixing belt 21 in the longitudinal direction. Fig.46The retaining portion 70a has an outer surface with a diameter smaller than the inner diameter of the loop of the fixing belt 21, and is inserted into the loop of the fixing belt 21 so that the fixing belt 21 is substantially not given circumferential tension when it is stationary (in other words, when not rotating), that is, it is retained in a so-called free belt method. On the other hand, the adjuster 70b has an outer diameter larger than the inner diameter of the loop of the fixing belt 21 to adjust the movement (in other words, deviation) of the fixing belt 21 in the length direction X. The protrusion 30 protrudes from the inner peripheral surface of the retaining portion 70a in a direction away from the heater 23.

[0288] As described above, the protrusion 30 provided on the heater bracket 24 or the flange 70 to support the lead 44 can ensure a large distance between the heater 23 and the lead 44 in an area where the temperature of the heater 23 is likely to rise, that is, in an area facing the heat generation area 60 and on the outside in the width direction of the minimum sheet passing area W2. As a result, the protrusion 30 of the above-mentioned embodiment can also suppress the temperature rise of the lead 44. Since the temperature of the flange 70 is less likely to rise than the temperature of the heater bracket 24, the flange 70 can more effectively reduce the temperature rise of the protrusion 30. That is, compared with the case where the protrusion 30 is provided on the heater bracket 24, by providing the protrusion 30 as a component between the heater bracket 24 and the lead 44 and separate from the heater bracket 24 on the flange 70, the temperature rise of the protrusion 30 can be more effectively suppressed. Therefore, in the embodiment in which the protrusion 30 is provided on the flange 70, the temperature rise of the lead 44 can be more effectively reduced. In addition, Fig.46 The number of the protrusions 30 shown is not limited to one, and may be a plurality of protrusions as in the above-described embodiment. In addition, the arrangement of the protrusions 30 and the shape of the protrusions 30 may be the same as in the above-described embodiment.

[0289] The above-described embodiments are illustrative and do not limit the present disclosure. Therefore, it should be understood that many additional modifications and changes may be made to the present disclosure in addition to the specific description herein, within the scope of the appended claims. In the above-described embodiments, the component between the heater bracket 24 and the lead 44 and separate from the heater bracket 24 is the sensor bracket 50 or the flange 70. However, as long as it is a component separate from the heater bracket 24, it may also be a component other than the sensor bracket 50 and the flange 70. For example, the component may be a protrusion separated from the heater bracket 24. The sensor bracket 50 and the protrusion 30 may be formed as one component. The flange 70 and the protrusion 30 may be formed as one component.

[0290] The imaging device to which the embodiments of the present disclosure are applicable is not limited to a central reference conveying system in which sheets of various sizes are conveyed so that the sheets of various sizes are conveyed with the center in the width direction as the reference. The embodiments of the present disclosure may also be applicable to an imaging device of an end conveying reference system in which sheets of various sizes are conveyed so that the sheets of various sizes are conveyed with one end in the width direction as the reference. Fig.47 As shown, the maximum sheet passing area W1 of the heater of the end conveyance reference system is an area having a maximum sheet width W1 or a length of W1+5 mm from the conveyance reference position r for conveying the sheets P1 and P2, and the minimum sheet passing area W2 is an area having a minimum sheet width W2 or a length of W2+5 mm from the conveyance reference position r. In the image forming apparatus using the end conveyance reference system, by providing the protrusion 30 in the area facing the width direction outside of the minimum sheet passing area W2 and in the heat generating area 60 of the heater 23, a large distance from the heater 23 to the lead 44 can be ensured, and similarly to the above-mentioned embodiment, the temperature rise of the lead 44 can be reduced.

[0291] The heater in the fixing device according to the present invention may have a positive temperature coefficient of resistance (PTC) characteristic. The so-called PTC characteristic is a characteristic that the resistance value increases as the temperature increases (at a constant voltage, the heater output decreases). By using a heater whose resistance heating element has a PTC characteristic, heat is generated quickly at a low temperature with a high output, and overheating can be prevented at a high temperature with a low output. Since the use of a heater with a PTC characteristic can effectively prevent the heating of the resistance heating element in the non-sheet passing area, the use of a heater with a PTC characteristic can further prevent the temperature increase of the lead. For example, if the temperature coefficient of resistance (TCR) of the PTC characteristic is in the range from about 300ppm / ℃ to about 4000ppm / ℃, the heater is manufactured at a low cost while ensuring the resistance value required for the heater. TCR is preferably in the range of 500ppm / ℃ to 2,000ppm / ℃. TCR is calculated by measuring the resistance values ​​at 25℃ and 125℃. For example, if the temperature increases by 100℃ and the resistance value increases by 10%, the TCR is 1,000ppm / ℃.

[0292] The embodiments of the present disclosure may be applicable to Figures 48 to 52 The fixing device shown in FIG. Figures 48 to 52 The structure of the fixing device shown in FIG.

[0293] Fig.48 The fixing device 20 shown is Figure 2 The fixing device 20 shown is different in the position of the temperature sensor 27 for detecting the temperature of the heater 23. In addition, Fig.48 The configuration shown is similar to Figure 2The configuration is the same as in Fig.48 In the fixing device 20 shown in FIG. 1 , the temperature sensor 27 is disposed upstream of the center M of the fixing nip N in the sheet passing direction (ie, near the nip entrance). Figure 2 In the fixing device 20 shown in FIG. 1 , the temperature sensor 27 is arranged to face the center M of the fixing nip N. Fig.48 As shown, the temperature sensor 27 provided upstream of the center M of the fixing nip N in the sheet passing direction can accurately detect the temperature near the nip entrance. Since the sheet P entering the fixing nip N is particularly likely to take away the heat of the fixing belt 21 in the portion near the nip entrance, the temperature sensor 27 accurately detecting the temperature at the portion near the nip entrance can ensure the fixing characteristics of the image and effectively prevent the occurrence of fixing offset (i.e., a state in which the toner image cannot be sufficiently heated).

[0294] Next, Fig.49 The fixing device 20 in the illustrated embodiment has a heating nip N1 of the fixing belt 21 heated by the heater 23 and a fixing nip N2 through which the sheet P passes, and the heating nip N1 and the fixing nip N2 are formed at different positions. Specifically, in addition to the heater 23, the fixing device 20 in the present embodiment further includes a nip forming pad 68 on the inner side of the loop of the fixing belt 21. The pressure roller 69 presses the heater 23 via the fixing belt 21 to form the heating nip N1, and the pressure roller 75 presses the nip forming pad 68 to form the fixing nip N2. In the above-mentioned fixing device 20, the heater 23 heats the fixing belt 21 in the heating nip N1, and the fixing belt 21 imparts heat to the sheet P in the fixing nip N2 to fix the unfixed image to the sheet P.

[0295] Next, Fig.50 The fixing device 20 shown is Fig.49 The fixing device 20 shown in the figure omits the above-mentioned pressure roller 69 adjacent to the heater 23, and includes the heater 23 formed into an arc shape having the curvature of the fixing belt 21. Fig.49 In this case, the arc heater 23 ensures that the contact length between the fixing belt 21 and the heater 23 is maintained in the belt rotation direction to effectively heat the fixing belt 21 .

[0296] Next, Fig.51 The fixing device 20 shown includes a pair of belts 71 and 72 as a pair of rotating bodies, and a roller 73 as another rotating body provided between the pair of belts 71 and 72. Fig.51 The heater 23 on the inner side of the ring of the belt 71 on the left side and the heater 23 on the inner side of the ring Fig.51The nip forming pad 74 is formed inside the loop of the belt 72 on the right side. The heater 23 contacts the roller 73 via the left belt 71, and the nip forming pad 74 contacts the roller 73 via the right belt 72, thereby forming the heating nip N1 and the fixing nip N2. In this case, the heater 23 heats the roller 73 via the left belt 71.

[0297] The imaging device according to the present embodiment is not limited to Figure 1 The color imaging device shown in FIG. Fig.52 Hereinafter, other embodiments of the imaging device to which this embodiment can be applied will be described.

[0298] Fig.52 The image forming apparatus 100 shown includes an image forming device 80 including a photosensitive drum and the like, a sheet conveyor including a timing roller pair 81 and the like, a sheet feeder 82, a fixing device 83, a sheet discharge device 84, and a reading device 85. The sheet feeder 82 includes a plurality of sheet feed trays, which respectively store sheets of different sizes.

[0299] The reading device 85 generates image data from the read image. The sheet feeder 82 stores a plurality of sheets P and feeds the sheets P to a conveying path. The timing roller pair 81 conveys the sheets P on the conveying path to the image forming device 80 .

[0300] The imaging device 80 forms a toner image on the sheet P. Specifically, the imaging device 80 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a charge eliminator. The fixing device 83 heats and presses the toner image to fix the toner image on the sheet P. The conveying roller conveys the sheet P on which the toner image has been fixed to the sheet discharge device 84. The sheet discharge device 84 discharges the sheet P to the outside of the imaging apparatus 100.

[0301] Next, refer to Fig.53 The fixing device 83 according to the present embodiment will be described. Fig.53 In the structure shown, Figure 2 The common structures of the fixing device 20 of the above-described embodiments are denoted by the same reference numerals, and the description thereof will be omitted.

[0302] like Fig.53 As shown, the fixing device 83 includes a fixing belt 21 , a pressure roller 22 , a heater 23 , a heater support 24 , a support post 25 , and a temperature sensor 27 .

[0303] A fixing nip N is formed between the fixing belt 21 and the pressure roller 22. The nip width of the fixing nip N is 10 mm, and the linear speed of the fixing device 83 is 240 mm / s.

[0304] The fixing belt 21 includes a polyimide base layer and a release layer, but does not include an elastic layer. The release layer is made of a heat-resistant film material such as fluorine resin. The outer ring diameter of the fixing belt 21 is about 24 mm.

[0305] The pressure roller 22 includes a core, an elastic layer, and a release layer. The outer diameter of the pressure roller 22 is 24 mm to 30 mm, and the thickness of the elastic layer 21b is 3 mm to 4 mm.

[0306] The heater 23 includes a base material, a heat insulating layer, a conductor layer including a resistance heating element, and an insulating layer, and is formed to have a thickness of 1 mm as a whole. The width of the heater 23 in the sheet conveying direction is, for example, 13 mm.

[0307] like Fig.54 As shown in FIG. 1 , the conductor layer of the heater 23 includes a plurality of resistance heating elements 56, a power supply line 59, and electrodes 58A to 58C. The plurality of resistance heating elements 56 are arranged at intervals in the length direction of the heater 23 (i.e., the direction indicated by the arrow X). Hereinafter, the portion between adjacent resistance heating elements 56 is referred to as a separation region B. Fig.54 As shown in the enlarged view of FIG. 1 , a separation area B is formed between adjacent resistance heating elements among the plurality of resistance heating elements 56 . Fig.54 The enlarged view of FIG. 1 shows two separation regions B, but the separation regions B are formed between adjacent resistance heating elements of all the plurality of resistance heating elements 56. Fig.54 In the figure, the direction indicated by the arrow Y is a direction that intersects or is orthogonal to the length direction X of the heater 23, and is referred to as the length intersecting direction. The length intersecting direction is different from the thickness direction of the substrate 55. In addition, the direction indicated by the arrow Y is a direction that intersects the arrangement direction of the plurality of resistance heating elements 56, a direction along the surface of the substrate 55 on which the resistance heating elements 56 are arranged, and is the short side direction of the heater 23, and is the same direction as the sheet conveying direction of the sheet passing through the fixing device.

[0308] The heater 23 includes a central heating portion 35B and end heating portions 35A and 35C located on both sides of the central heating portion 35B. The central heating portion 35B and the end heating portions 35A and 35C are composed of a plurality of resistance heating elements 56. The end heating portions 35A and 35C can generate heat separately from the central heating portion 35B. For example, Fig.54In the embodiment, the left electrode 58A and the central electrode 58B are selected from the three electrodes 58A to 58C, and a voltage is applied between the left electrode 58A and the central electrode 58B so that the end heating portions 35A and 35C adjacent to both sides of the central heating portion 35B generate heat. By applying a voltage between the left electrode 58A and the right electrode 58C, the central heating portion 35B generates heat. In order to fix the image to a small sheet, the central heating portion 35B can generate heat alone. In order to fix the image to a large sheet, all the heating portions 35A to 35C can generate heat. As a result, the heater in the fixing device can generate heat according to the size of the sheet.

[0309] like Fig.55 As shown, the heater support 24 of this embodiment has a recess 24a for accommodating and holding the heater 23. The recess 24a is formed on the side of the heater support 24 facing the heater 23. The recess 24a has: a bottom 24f, which is formed in a rectangular shape of substantially the same size as the heater 23; and four side walls 24b, 24c, 24d, and 24e, which are respectively arranged on the four sides of the bottom 24f. Fig.55 The right side wall 24e is omitted. The recessed portion 24a may have an opening portion that opens toward one end in the length direction of the heater 23. The opening portion is formed by removing one of a pair of left side walls 24d and right side walls 24e that intersect the length direction X of the heater 23 (i.e., the arrangement direction of the resistance heating element 56).

[0310] like Fig.56 As shown, the heater 23 and the heater holder 24 of the present embodiment are held by a connector 86. The connector 86 includes a housing made of a resin such as LCP and a plurality of contact terminals fixed to the inner surface of the housing.

[0311] When the connector 86 is mounted on the heater 23 and the heater bracket 24, it is oriented in a direction intersecting the longitudinal direction X of the heater 23, that is, in the arrangement direction of the resistance heating element 56 (see Fig.56 The connector 86 is mounted to one end of the heater 23 and one end of the heater bracket 24 in the length direction X of the heater 23, i.e., the arrangement direction of the resistive heating element 56. One end of the heater 23 and one end of the heater bracket 24 are farther away from the portion of the pressure roller 22 that receives the driving force from the driving motor than the other end of the heater 23 and the other end of the heater bracket 24, respectively. The connector 86 and the heater bracket 24 may have a convex portion and a concave portion to connect the connector 86 to the heater bracket 24. The convex portion provided on one of the connector 86 and the heater bracket 24 engages with the concave portion provided on the other, and moves relatively in the concave portion to connect the connector 86 to the heater bracket 24.

[0312] After the connector 86 is mounted to the heater 23 and the heater bracket 24, the heater 23 and the heater bracket 24 are clamped by the connector 86. In this state, the contact terminals respectively contact and press against the electrodes of the heater 23, and the resistance heating element 56 is electrically connected to a power source provided in the imaging device via the connector 86. As a result, the power source can supply power to the resistance heating element 56.

[0313] Fig.56 The flanges 87 shown are belt holders provided at both ends of the fixing belt 21 in the longitudinal direction and contacting the inner peripheral surface of the fixing belt 21 to hold the fixing belt 21. The flanges 87 are inserted into both ends of the support 25 and fixed to a pair of side plates as a frame member of the fixing device.

[0314] Fig.57 2 is a diagram showing the arrangement of the temperature sensor 27 and the thermostat 88 included in the fixing device according to the present embodiment. Each thermostat 88 cuts off the current flowing through the resistance heating element under a certain condition.

[0315] like Fig.57 As shown in FIG. 1 , one of the temperature sensors 27 according to the present embodiment is arranged to face the inner peripheral surface of the fixing belt 21 near the center Xm of the fixing belt 21 in the length direction of the fixing belt 21 indicated by the arrow X, and the other of the temperature sensors 27 is arranged to face the inner peripheral surface of the fixing belt 21 near the end of the fixing belt 21 in the length direction of the fixing belt 21. One temperature sensor 27 is arranged in a separation area B (see FIG. 1 ) between the resistance heating element of the heater 23. Fig.54 ) corresponding to the position.

[0316] In addition, one of the thermostats 88 is disposed to face the inner peripheral surface of the fixing belt 21 near the center Xm of the fixing belt 21, and the other of the thermostats 88 is disposed to face the inner peripheral surface of the fixing belt 21 near the end of the fixing belt 21. Each thermostat 88 detects the temperature of the inner peripheral surface of the fixing belt 21 or the ambient temperature near the inner peripheral surface of the fixing belt 21. The thermostat 88 cuts off the current flowing to the heater 23 in response to detecting a temperature exceeding a prescribed threshold value.

[0317] like Fig.57 and Fig.58 As shown, the flanges 87 holding both ends of the fixing belt 21 each have a slide groove 87a. The slide groove 87a extends in the direction of contact and separation of the fixing belt 21 relative to the pressure roller 22. The engaging portion of the housing of the fixing device 20 engages with the slide groove 87a. The fixing belt 21 can move relative to the pressure roller 22 in the contact and separation direction through the relative movement of the engaging portion in the slide groove 87a.

[0318] The present disclosure is also applicable to a fixing device having the following configuration.

[0319] Fig.59 is a schematic diagram of a fixing device having a different structure from the above-mentioned fixing device. The above-mentioned embodiment can be applied to Fig.59 Fixing device in.

[0320] like Fig.59 As shown, the fixing device 20 according to the present embodiment includes a fixing belt 21 as a fixing rotating body, a pressure roller 22 as an opposing rotating body or a pressure rotating body, a heater 23 as a heat source, a heater holder 24 as a heat source holding member, a support 25 as a supporting member, a temperature sensor (thermistor) 27 as a temperature detector, and a first high thermal conductive member 89. The fixing belt 21 is an endless belt. The pressure roller 22 contacts the outer peripheral surface of the fixing belt 21 to form a fixing nip N between the pressure roller 22 and the fixing belt 21. The heater 23 heats the fixing belt 21. The heater holder 24 holds the heater 23.

[0321] The support column 25 supports the heater bracket 24. The temperature sensor 27 detects the temperature of the first high thermal conductive member 89. That is, the fixing device 20 of the present embodiment has the same Figure 2 The fixing device shown in FIG. has basically the same structure. Fig.59 The direction orthogonal to the paper surface of the fixing belt 21 is the length direction of the fixing belt 21, the pressure roller 22, the heater 23, the heater bracket 24, the support 25, and the first high thermal conductive member 89. Hereinafter, this direction is simply referred to as the length direction. It should be noted that the length direction is also the width direction of the sheet being conveyed, the belt width direction of the fixing belt 21, and the axial direction of the pressure roller 22.

[0322] The heater 23 of this embodiment is Fig.56 The heater 23 shown in FIG. 1 is the same as the heater 23 shown in FIG. 1 , in which a plurality of resistance heating elements 56 are arranged at intervals in the length direction of the heater 23. In the heater 23 including the plurality of resistance heating elements 56 arranged at intervals, the temperature of the heater 23 in the separation area B corresponding to the intervals between the resistance heating elements 56 tends to be lower than the temperature of the heater 23 in the portion completely occupied by the resistance heating elements 56. Therefore, the temperature of the fixing belt 21 corresponding to the separation area B also becomes low, which may cause uneven temperature distribution of the fixing belt 21 in the length direction.

[0323] In order to prevent the temperature drop in the separation area B and reduce the temperature non-uniformity in the length direction of the fixing belt 21, the fixing device in this embodiment includes a first highly thermally conductive member 89. Next, the first highly thermally conductive member 89 will be described in detail.

[0324] like Fig.59 As shown, the first high thermal conductivity component 89 is Fig.59The heater 23 is disposed between the heater 23 and the support 25 in the left-right direction, and in particular, is sandwiched between the heater 23 and the heater support 24 .

[0325] One side of the first highly thermally conductive member 89 contacts the back surface of the base material 55 of the heater 23 , and the other side (ie, the side opposite to the one side) of the first highly thermally conductive member 89 contacts the heater holder 24 .

[0326] The support column 25 has two vertical portions 25a extending in the thickness direction of the heater 23 and each having a contact surface 25a1 contacting the back side of the heater support 24 to support the heater support 24, the first high thermal conductive member 89 and the heater 23. Fig.59 The contact surface 25a1 is located outside the resistance heating element 56. The above structure prevents heat from being transferred from the heater 23 to the support 25, so that the heater 23 can heat the fixing belt 21 effectively.

[0327] like Fig.60 As shown, the first high thermal conductive component 89 is a plate having a certain thickness of 0.3 mm, for example, a plate having a length of 222 mm in the longitudinal direction and a width of 10 mm in the direction intersecting the longitudinal direction. In this embodiment, the first high thermal conductive component 89 is composed of a single plate, but may also be composed of a plurality of plates. Fig.60 In, omitted Fig.59 The guide 26 is shown.

[0328] The first high thermally conductive member 89 is inserted into the recess 24a of the heater holder 24, and the heater 23 is placed thereon. Thus, the first high thermally conductive member 89 is sandwiched between the heater holder 24 and the heater 23. In the present embodiment, the length of the first high thermally conductive member 89 in the longitudinal direction is substantially the same as the length of the heater 23 in the longitudinal direction. The two side walls 24d and 24e extending in the direction intersecting the longitudinal direction of the recess 24a restrict the movement of the heater 23 and the first high thermally conductive member 89 in the longitudinal direction, and function as a longitudinal direction restriction portion. Reducing the positional deviation of the first high thermally conductive member 89 in the longitudinal direction in the fixing device improves the heat transfer efficiency relative to the target range in the longitudinal direction. The two side walls 24b and 24c extending in the longitudinal direction of the recess 24a restrict the movement of the heater 23 and the first high thermally conductive member 89 in the direction intersecting the longitudinal direction, and function as a longitudinal cross direction restriction portion.

[0329] The range in which the first high thermally conductive member 89 is arranged in the longitudinal direction indicated by the arrow X is not limited to Fig.60 For example, Fig.61 As shown, the first high thermal conductive member 89 may be arranged only within the range in the longitudinal direction where the heating resistor 56 is arranged (see Fig.61 The slashed part of Fig.62 As shown, the first high thermal conductivity component 89 may be arranged only in the entire separation area (in other words, the interval area between the resistance heating elements) at the position corresponding to the separation area B in the length direction indicated by the arrow X. Fig.62 In order to facilitate the description, the heating resistor 56 and the first high thermal conductive component 89 are Fig.62 The first high thermal conductive member 89 may be arranged at a portion of the resistive heating element 56 in the direction intersecting the longitudinal direction (the direction indicated by the arrow Y), or may be arranged at a position substantially the same as the position in the direction intersecting the longitudinal direction. Fig.63 As shown in the example, the heating resistor 56 is arranged in a direction intersecting the longitudinal direction (the direction indicated by the arrow Y) so as to cover all the heating resistors 56. Fig.63 As shown, the first high thermal conductive member 89 may be arranged to be opposite to a portion of the adjacent resistance heating elements 56 in addition to the spacing area between the adjacent resistance heating elements 56. The first high thermal conductive member 89 may be arranged to be opposite to the entire separation area B of the heater 23, or may be arranged to be opposite to the separation area B of the heater 23. Fig.63 The first high thermal conductive member 89 may be disposed opposite to one separation region B as shown in the figure, or may be disposed opposite to a part of the separation regions B among the plurality of separation regions B. The first high thermal conductive member 89 may be disposed opposite to all the separation regions B of the heater 23, or may be disposed opposite to the separation regions B as shown in the figure. Fig.63 As shown in the figure, it is arranged relative to one separation area B, and can also be arranged relative to a part of the separation areas B among the plurality of separation areas B.

[0330] The first high thermal conductive member 89 is sandwiched between the heater 23 and the heater support 24 by the pressing force of the pressure roller 22, and is in close contact with the heater 23 and the heater support 24. By making the first high thermal conductive member 89 contact the heater 23, the heat conduction efficiency of the heater 23 in the longitudinal direction is improved. The first high thermal conductive member 89 opposite to the separation area B improves the thermal conductivity of the portion of the heater 23 opposite to the separation area B in the longitudinal direction, and transfers heat to the portion of the heater 23 opposite to the separation area B, so that the temperature of the portion of the heater 23 opposite to the separation area B rises. Therefore, the first high thermal conductive member 89 reduces the temperature non-uniformity of the heater 23 in the longitudinal direction and the temperature non-uniformity of the fixing belt 21 in the longitudinal direction. As a result, according to the above structure, it is possible to prevent the fixing unevenness and gloss unevenness of the image fixed on the sheet. Since the heater 23 does not need to generate additional heat to ensure sufficient fixing performance in the portion of the heater 23 facing the separation area B, it is possible to save energy consumption of the fixing device. The first high thermal conductivity component 89 configured over the entire area in which the resistive heating element 56 is configured along the length direction improves the heat transfer efficiency of the heater 23 over the entire area of ​​the main heating area of ​​the heater 23 (i.e., the area facing the imaging area of ​​the sheet passing through the fixing device), and reduces the temperature non-uniformity of the heater 23 and the temperature non-uniformity of the fixing belt 21 along the length direction.

[0331] In addition, the combination of the first high thermal conductivity component 89 and the resistance heating element 56 having the PTC characteristic effectively prevents overheating of the non-sheet passing area (i.e., the area of ​​the fixing belt that does not contact the small sheet) of the fixing belt 21 when the small sheet passes through the fixing device 20. The PTC characteristic is a characteristic in which the resistance value increases as the temperature rises, for example, the heater output decreases at a constant voltage. The resistance heating element 56 having the PTC characteristic effectively reduces the heat generated by the resistance heating element 56 in the non-sheet passing area, and the first high thermal conductivity component 89 effectively transfers the heat from the non-sheet passing area where the temperature rises to the sheet passing area which is the area where the fixing belt contacts the sheet. As a result, overheating of the non-sheet passing area is effectively prevented.

[0332] Since the heat generation of the separation area B is small, the temperature of the heater 23 around the separation area B is reduced. Therefore, the first high thermal conductive member 89 may be arranged to face the separation area B. Fig.64 As shown, by making the first high thermal conductivity member 89 face the enlarged separation area C including the separation area B and the area around it, the heat transfer efficiency in the length direction of the separation area B and the area around it can be improved, and the temperature unevenness in the length direction of the heater 23 can be effectively reduced. The first high thermal conductivity member 89 facing the entire area where all the resistance heating elements 56 are arranged in the length direction reduces the temperature unevenness of the heater 23 (and the fixing belt 21) in the length direction.

[0333] Next, another embodiment of the fixing device is described.

[0334] Fig.65 The fixing device 20 shown in the figure includes a second highly thermally conductive member 90 between the heater support 24 and the first highly thermally conductive member 89. The second highly thermally conductive member 90 is disposed in the stacking direction of the heater support 24, the support 25, and the first highly thermally conductive member 89. Fig.65 The second highly thermally conductive member 90 is disposed at a position different from the first highly thermally conductive member 89 in the left-right direction. Specifically, the second highly thermally conductive member 90 is disposed so as to overlap with the first highly thermally conductive member 89. The fixing device in this embodiment includes a temperature sensor 27 (i.e., a thermistor) which is connected to the first highly thermally conductive member 89. Fig.59 The fixing device shown in is the same. Fig.65 The cross section is shown without the temperature sensor 27 being provided.

[0335] The second highly thermally conductive member 90 is formed of a material having a higher thermal conductivity than the substrate 55, such as graphene or graphite. In the present embodiment, the second highly thermally conductive member 90 is formed of a graphite sheet having a thickness of 1 mm. Alternatively, the second highly thermally conductive member 90 may be a plate made of aluminum, copper, silver, or the like.

[0336] like Fig.66 As shown, a plurality of second highly thermally conductive members 90 are arranged at intervals in the length direction on the recessed portion 24a of the heater holder 24. A plurality of holes are formed in the recessed portion 24a of the heater holder 24, and the second highly thermally conductive members 90 are arranged in the plurality of holes. A gap is formed between the heater holder 24 and both sides of the second highly thermally conductive members 90 in the length direction. The gap prevents heat from being transferred from the second highly thermally conductive members 90 to the heater holder 24, and the heater 23 effectively heats the fixing belt 21. Fig.66 In, omitted Fig.65 The guide 26 is shown.

[0337] like Fig.67 As shown, the second high thermally conductive component 90 (see the oblique line portion) is arranged at a position corresponding to the separation region B in the length direction indicated by the arrow X, and is opposed to at least a portion of the adjacent resistive heating element 56 in the length direction. In particular, the second high thermally conductive component 90 of the present embodiment is opposed to the entire separation region B. Fig.67 (and the following Fig.69 ) represents the first highly thermally conductive member 89 that is opposed to the entire region in which all the resistance heating elements 56 are arranged in the longitudinal direction. The arrangement range of the first highly thermally conductive member 89 in the longitudinal direction is not limited to this.

[0338] The fixing device according to the present embodiment includes a second high thermal conductivity component 90, which is arranged at a position corresponding to the separation area B in the length direction, and at this position, at least a part of each adjacent resistance heating element 56, except for the first high thermal conductivity component 89, faces the second high thermal conductivity component 90. According to the above structure, the heat transfer efficiency in the length direction of the separation area B can be further improved, and the temperature unevenness in the length direction of the heater 23 can be more effectively reduced. Fig.68 As shown, the first high thermal conductivity component 89 and the second high thermal conductivity component 90 may be arranged to face the entire separation area between the resistance heating element 56. According to the above structure, the heat transfer efficiency of the portion of the heater 23 corresponding to the separation area is higher than the heat transfer efficiency of the other portions of the heater 23. Fig.68 For the sake of convenience, the heating resistor 56, the first high thermal conductive component 89 and the second high thermal conductive component 90 are Fig.68 The first high thermal conductivity component 89 and the second high thermal conductivity component 90 may be arranged opposite to a part of the resistive heating element 56 in the direction intersecting the longitudinal direction, or may be arranged in a manner to cover the entire resistive heating element 56 in the direction intersecting the longitudinal direction.

[0339] The first high thermal conductive member 89 and the second high thermal conductive member 90 may both be made of a graphene sheet. The first high thermal conductive member 89 and the second high thermal conductive member 90 made of a graphene sheet have high thermal conductivity in a predetermined direction along the surface of the graphene, that is, not in the thickness direction but in the length direction. Therefore, the above structure can effectively reduce the temperature non-uniformity of the fixing belt 21 in the length direction and the temperature non-uniformity of the heater 23 in the length direction.

[0340] Graphene is a flake powder. Fig.71 As shown, graphene has a planar hexagonal lattice structure of carbon atoms. Graphene sheets are usually single layers. Monolayer carbon may contain impurities. Graphene may have a fullerene structure. Fullerene structures are generally considered to be compounds formed by polycyclic bodies including an even number of carbon atoms in the form of five-membered rings and six-membered rings condensed into a cage, for example, C60, C70 and C80 fullerenes or other closed cage structures with tri-coordinated carbon atoms.

[0341] Graphene sheets are artificially produced by, for example, a chemical vapor deposition (CVD) method.

[0342] A commercially available product can be used as the graphene sheet. The size and thickness of the graphene sheet or the number of layers of the graphene sheet described later can be measured, for example, by a transmission electron microscope (TEM).

[0343] Graphite obtained by multilayering graphene has large thermal conductivity anisotropy. Fig.72 As shown, the condensed six-membered ring layer of carbon atoms has a planar extended layer, and the layer has a multi-layer overlapping crystal structure. Between the carbon atoms in the crystal structure, covalent bonds are formed between adjacent carbon atoms in the layer, and van der Waals bonds are formed between carbon atoms between the layers. Moreover, covalent bonds have a bonding force greater than that of van der Waals bonds. Therefore, there is a large anisotropy between the bonds between carbon atoms in the layer and between carbon atoms in different layers. That is, the heat transfer efficiency in the length direction of the first high thermal conductive component 89 and the second high thermal conductive component 90 composed of graphite is higher than the heat transfer efficiency in the thickness direction of the first high thermal conductive component 89 and the second high thermal conductive component 90 (that is, the stacking direction of these components), so the heat transferred to the heater bracket 23 can be reduced. Therefore, the above structure can effectively reduce the temperature non-uniformity of the heater 22 in the arrangement direction, and can minimize the heat transferred to the heater bracket 23. The first highly thermally conductive member 89 and the second highly thermally conductive member 90 made of graphite are not oxidized at about 700 degrees or less, and therefore the first highly thermally conductive member 89 and the second highly thermally conductive member 90 have excellent heat resistance.

[0344] The physical properties and dimensions of the graphite sheet can be appropriately changed according to the functions required of the first high thermal conductive component 89 and the second high thermal conductive component 90. For example, by using high-purity graphite or single-crystal graphite, or increasing the thickness of the graphite sheet, the anisotropy of heat conduction can be increased. By using a thin graphite sheet, the heat capacity of the fixing device can be reduced, and high-speed printing can be performed. In the case where the width of the fixing nip N or the heater 22 is large, the width of the first high thermal conductive component 89 or the second high thermal conductive component 90 in the longitudinal direction can also be increased accordingly.

[0345] From the viewpoint of improving mechanical strength, the number of layers of the graphite sheet is preferably not less than 11. The graphite sheet may partially include a single-layer portion and a multi-layer portion.

[0346] The second high thermally conductive member 90 may be provided at a position corresponding to the separation region B in the longitudinal direction, and may overlap at least a portion of the adjacent heating resistor 56. Fig.67 For example, Fig.69 As shown, the second highly thermally conductive component 90A may extend toward both ends of the length-crossing direction longer than the substrate 55 in the direction crossing the length direction indicated by arrow Y. The second highly thermally conductive component 90B may face the arrangement range of the resistive heating element 56 in the length-crossing direction. The second highly thermally conductive component 90C faces a portion of the separation region B and a portion of each adjacent resistive heating element 56.

[0347] like Fig.70As shown, in this embodiment, a thickness direction ( Fig.70 That is, in the recessed portion 24a (see FIG. 24 ) where the heater 23, the first highly thermally conductive component 89, and the second highly thermally conductive component 90 are arranged, the heater holder 24 has a space of 100 mm. Fig.66 ), in a portion of the longitudinal direction, the depth of the recess 24a is set to be deeper than the other portion receiving the first high thermal conductive component 89, and a gap 24g is provided as a heat insulating layer. As a result, the contact area between the heater holder 24 and the first high thermal conductive component 89 can be limited to a minimum. Therefore, the heat transfer from the first high thermal conductive component 89 to the heater holder 24 can be suppressed, and the heater 23 can effectively heat the fixing belt 21. In the cross section of the fixing device provided with the second high thermal conductive component 90, as in the above-mentioned embodiment Fig.65 As shown, the second high thermal conductive member 90 abuts against the heater support 24 .

[0348] The gap 24g of this embodiment is Fig.70 The first high thermal conductive member 89 is arranged over the entire area of ​​the resistance heating element 56 in the vertical direction, that is, the length-crossing direction. The above-mentioned configuration effectively prevents heat transfer from the first high thermal conductive member 89 to the heater bracket 24, and the heater 23 effectively heats the fixing belt 21. The fixing device may include a heat insulating layer made of a heat insulating material having a lower thermal conductivity than the heater bracket 24, instead of a space serving as a heat insulating layer like the gap 24g.

[0349] In the present embodiment, the second highly thermally conductive member 90 is a member different from the first highly thermally conductive member 89, but the present embodiment is not limited thereto. For example, by making the portion of the first highly thermally conductive member 89 facing the separation region B thicker than other portions, the first highly thermally conductive member 89 can also function as the second highly thermally conductive member 90.

[0350] In the above, various configurations of the fixing device and the image forming apparatus to which the embodiments of the present invention can be applied are described. Even in the fixing device and the image forming apparatus of the above configuration, effects similar to the above effects in the embodiments can be obtained by applying the present invention. That is, by applying the above embodiment to the fixing device, it is possible to prevent the temperature of the lead wire facing the non-sheet passing area from rising, and to improve the durability of the lead wire.

[0351] In the above-mentioned embodiment, the present disclosure is applicable to a fixing device as an example of a heating device. The heating device to which the present embodiment can be applied is not limited to the fixing device. The present embodiment can be applied to, for example, a drying device such as a dryer for drying liquid such as ink applied to paper, a laminator for pressurizing and heating a film as a covering member on the surface of a sheet such as paper, a heat sealer for heating and pressurizing a sealing portion of a packaging material, and the like.

[0352] The above embodiments of the present disclosure have at least the following aspects:

[0353] First aspect

[0354] In a first aspect, a heating device includes a pair of rotating bodies, a heater, a temperature sensor, a conductor, a plurality of conductor supports, and a component supporting the plurality of conductor supports. The pair of rotating bodies are in contact with each other to form a clamping portion through which a sheet passes. The heater heats at least one of the pair of rotating bodies. The temperature sensor detects the temperature of the heater. The conductor is flexible and connected to the temperature sensor. A plurality of conductor supports support the conductor and extend in a direction away from the heater. The plurality of conductor supports include a first conductor support and a second conductor support. The first conductor support faces the outside of a predetermined area of ​​the heater in the width direction of the sheet and is arranged at a first interval in the width direction. The second conductor support faces the predetermined area of ​​the heater and is arranged at a second interval greater than the first interval in the width direction. The component has a first side facing the heater and a second side opposite to the first side.

[0355] Second aspect

[0356] In a second aspect, in the heating device according to the first aspect, further comprising a heater holder which holds the heater, and the component is located between the heater holder and the conductor.

[0357] The third aspect

[0358] In a third aspect, in the heating device according to the second aspect, the component is a sensor holder that holds the temperature sensor.

[0359] The fourth aspect

[0360] In a fourth aspect, in the heating device according to the first aspect, the component is a heater holder that holds the heater.

[0361] Fifth Aspect

[0362] In a fifth aspect, in the heating device according to the fourth aspect, the heater holder and the conductor support are formed as one component.

[0363] The sixth aspect

[0364] In a sixth aspect, in the heating device according to any one of the first to fifth aspects, the predetermined area of ​​the heater faces an area where a sheet having a minimum width in a width direction passes.

[0365] Seventh Aspect

[0366] In a seventh aspect, in the heating device according to any one of aspects 1 to 6, the heater includes a plurality of heat generators arranged at intervals in the width direction, and at least one of the plurality of conductor supports overlaps a region between the heat generators in the width direction.

[0367] Eighth Aspect

[0368] In an eighth aspect, in a heating device according to any one of aspects 1 to 7, the plurality of conductor supports protrude from the second side of the component in a direction away from the heater, and a height from the second side of the component to a top end of at least one of the plurality of conductor supports is higher than a height from the second side of the component to a position where the conductor is connected to the temperature sensor.

[0369] Ninth Aspect

[0370] In the ninth aspect, in a heating device according to any one of aspects 1 to 8, the heater includes a heat generator located at the center of the heater along the sheet conveying direction, at least one of the plurality of conductor supports protrudes from the second side of the component in a direction away from the heater, and supports the conductor at a position offset from the center of the heater along the sheet conveying direction.

[0371] Tenth Aspect

[0372] In the tenth aspect, in the heating device according to the ninth aspect, the height from the second side of the component to the central position of at least one of the multiple conductor supports in the sheet conveying direction is higher than the height from the second side of the component to the top end of each of the two sides of at least one of the multiple conductor supports in the sheet conveying direction.

[0373] Aspect 11

[0374] In the eleventh aspect, in the heating device according to any one of the first to tenth aspects, it further includes: a pillar, which supports the heater bracket as the component; and a low thermal conductor, which is arranged between the pillar and the conductor and has a thermal conductivity lower than the thermal conductivity of the pillar.

[0375] Aspect 12

[0376] In a twelfth aspect, in the heating device according to any one of the first to eleventh aspects, the temperature sensor faces a region where a sheet having a minimum width in a width direction passes.

[0377] Aspect 13

[0378] In a thirteenth aspect, a fixing device includes the heating device according to any one of the first to twelfth aspects, for fixing an unfixed image onto a sheet.

[0379] Aspect 14

[0380] In a fourteenth aspect, an image forming apparatus includes the fixing device according to the thirteenth aspect and one of the heating devices according to any one of the first to twelfth aspects.

[0381] This patent application is based upon and claims the benefit of priority from Japanese Patent Application No. 2022-078180 filed with the Japan Patent Office on May 11, 2022, and Japanese Patent Application No. 2022-086031 filed with the Japan Patent Office on May 26, 2022, the disclosures of which are incorporated herein in their entirety by reference.

[0382] Reference numerals list

[0383] 20 Fixing device (heating device)

[0384] 21 fixing belt (first rotating body)

[0385] 22 pressure roller (second rotating body)

[0386] 23 Heater (heat source)

[0387] 24 Heater bracket

[0388] 25 Pillars

[0389] 27 Temperature sensor (temperature detector)

[0390] 30 protrusion (conductor support)

[0391] 30m sheet conveying direction center

[0392] 44 lead wire (conductor)

[0393] 50 sensor bracket

[0394] 56 resistance heating element (heat generator)

[0395] 63 Low thermal conductivity

[0396] 100 imaging devices

[0397] N clamping part

[0398] P sheet (paper)

[0399] W1 Maximum sheet passing area

[0400] W2 minimum sheet passing area

[0401] X length direction

Claims

1. A heating device, comprising: a pair of rotating bodies which contact each other to form a clamping portion through which the sheet passes; a heater configured to heat at least one of the pair of rotating bodies; a temperature sensor configured to detect a temperature of the heater; A conductor, which is flexible and connected to the temperature sensor; a plurality of conductor supports supporting the conductors and extending in a direction away from the heater, The plurality of conductor supports comprises: first conductor supports facing the outside of a predetermined area of ​​the heater in the width direction of the sheet and arranged at first intervals in the width direction; as well as second conductor supports facing the predetermined area of ​​the heater and arranged at a second interval greater than the first interval in the width direction; as well as A member supports the plurality of conductor supports and has a first side facing the heater and a second side opposite to the first side.

2. The heating device according to claim 1, further comprising a heater support that holds the heater; in, The component is located between the heater support and the conductor.

3. The heating device according to claim 2, in, The component is a sensor holder that holds the temperature sensor.

4. The heating device according to claim 1, in, The component is a heater support that holds the heater.

5. The heating device according to claim 4, in, The heater holder and the conductor support are formed as one part.

6. The heating device according to any one of claims 1 to 5, in, The predetermined area of ​​the heater faces an area where a sheet having a minimum width in a width direction passes.

7. The heating device according to any one of claims 1 to 6, in, The heater includes a plurality of heat generators arranged at intervals in the width direction, and At least one of the plurality of conductor supports overlaps with a region between the heat generators in the width direction.

8. The heating device according to any one of claims 1 to 7, in, The plurality of conductor supports protrude from the second side of the component in a direction away from the heater, and wherein a height from the second side of the component to a top end of at least one of the plurality of conductor supports is higher than a height from the second side of the component to a location where the conductor is connected to the temperature sensor.

9. The heating device according to any one of claims 1 to 8, in, The heater includes a heat generator located at the center of the heater in the sheet conveying direction, and wherein at least one of the plurality of conductor supports protrudes from the second side of the member in a direction away from the heater, and supports the conductor at a position offset from a center of the heater in the sheet conveying direction.

10. The heating device according to claim 9, in, The height from the second side of the component to the central position of at least one of the plurality of conductor supports in the sheet conveying direction is higher than the height from the second side of the component to the top end of each of the two sides of at least one of the plurality of conductor supports in the sheet conveying direction.

11. The heating device according to any one of claims 1 to 10, further comprising: a support column that supports a heater bracket as the component; and The low thermal conductor is disposed between the support and the conductor and has a thermal conductivity lower than that of the support.

12. The heating device according to any one of claims 1 to 11, in, The temperature sensor faces a region where a sheet having a minimum width in a width direction passes.

13. A fixing device comprising the heating device according to any one of claims 1 to 12, for fixing an unfixed image onto a sheet.

14. An image forming apparatus comprising the fixing device according to claim 13 and one of the heating device according to any one of claims 1 to 12.

Images