Heating device and image forming apparatus

Abstract

To suppress a film from being holed.SOLUTION: Provided is a heating device 9 for heating a recording material P in a nip part N and comprising a cylindrical film 23 which is rotatable, a heating unit 50 for heating the film 23 and provided in the internal space of the film 23, a support member 21 for holding the heating unit 50, contacting the inner circumferential surface of the film 23, and guiding the rotation of the film 23, and a rotor 30 for forming a nip part N between the film 23 and itself. One of the heating unit 50 and the support member 23 includes an engagement part 51a located in a sheet passing region in the width direction of the recording material P orthogonal to a conveyance direction of the recording material P, and the other includes a part 21b to be engaged that engages with the engagement part 51a. The position of the heating unit 50 relative to the support member 21 in the conveyance direction is determined due to the engagement of the engagement part 51a with the part 21b to be engaged, and the engagement part 51a and the part 21b to be engaged are located downstream of an inlet of the nip part N and located upstream of an outlet of the nip part N in the conveyance direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a heating device such as a fixing device mounted in an image forming apparatus such as a copying machine or printer using an electrophotographic or electrostatic recording system, or a gloss imparting device that improves the glossiness of a toner image by reheating a fixed toner image on a recording material, and also to an image forming apparatus equipped with such a heating device. [Background technology]

[0002] A heating device to be mounted on an electrophotographic printer has been disclosed that includes a heater having a heating element on a substrate made of metal or the like, a flexible member that moves while in contact with the heater, and a pressure roller that forms a nip portion with the heater via the flexible member (Patent Document 1). A recording material carrying an unfixed toner image is heated while being sandwiched and conveyed in the nip portion of the heating device, and the toner image on the recording material is fixed to the recording material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-275671 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the above configuration, when recording material having protrusions such as staples or unintentional attachments is conveyed to the heating device, holes may be made in the flexible film, etc. If a hole is made in the film, the toner image is not heated sufficiently in the holed area, which can result in poor fixing.

[0005] The present invention has been made in view of the above problems, and has an object to suppress the formation of holes in a film. [Means for solving the problem]

[0006] In order to achieve the above object, the heating device of the present invention comprises: A rotatable cylindrical film; A heater is provided in the internal space of the film and heats the film. and a heat conducting member that contacts the inner circumferential surface of the film and conducts heat from the heater to the film. A heating unit; a support member that holds the heating unit and contacts an inner circumferential surface of the film to guide the rotation of the film; a rotating body that forms a nip portion between the rotating body and the film; Equipped with In the heating device that heats the recording material at the nip portion, before Support part The material is an engaging portion located within a paper passing area in a width direction of the recording material that is perpendicular to the conveyance direction of the recording material; The heat conduction member is an engaged portion that engages with the engaging portion, the engaging portion engages with the engaged portion, thereby determining a position of the heating unit in the transport direction relative to the support member; In the conveying direction, the engaging portion and the engaged portion are located downstream of an entrance of the nip portion and upstream of an exit of the nip portion. In order to achieve the above object, the heating device of the present invention comprises: A rotatable cylindrical film; a heater provided in an internal space of the film for heating the film, the heater including a substrate, a heating element provided on the substrate, and a protective layer covering the heating element, the heating element generating heat when energized; a support member that holds the heater and contacts an inner circumferential surface of the film to guide the rotation of the film; a rotating body that forms a nip portion between the rotating body and the film; Equipped with In the heating device that heats the recording material at the nip portion, the heater has an engagement portion located within a paper passing region in a width direction of the recording material that is perpendicular to a conveyance direction of the recording material, the support member has an engaged portion that engages with the engaging portion at an end portion on the upstream side in the conveying direction, the engaging portion engages with the engaged portion, thereby determining the position of the heater in the transport direction relative to the support member; In the conveying direction, the engaging portion and the engaged portion are located downstream of an entrance of the nip portion and upstream of an exit of the nip portion. In order to achieve the above object, the heating device of the present invention comprises: A rotatable cylindrical film; a heater provided in an internal space of the film for heating the film, the heater including a substrate, a heating element provided on the substrate, and a protective layer covering the heating element, the heating element generating heat when energized; a support member that holds the heater and contacts an inner circumferential surface of the film to guide the rotation of the film; a rotating body that forms a nip portion between the rotating body and the film; Equipped with In the heating device that heats the recording material at the nip portion, the support member has an engaging portion located within a paper passing area in a width direction of the recording material that is perpendicular to a conveyance direction of the recording material, the heater has an engaged portion that engages with the engaging portion, the engaging portion engages with the engaged portion, thereby determining the position of the heater in the transport direction relative to the support member; In the conveying direction, the engaging portion and the engaged portion are located downstream of an entrance of the nip portion and upstream of an exit of the nip portion. [Effects of the Invention]

[0007] According to the present invention, it is possible to prevent holes from being formed in the film. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the fixing device according to the first embodiment. [Figure 3] FIG. 2 is a perspective view of a film unit and a heat-conducting member according to the first embodiment. [Figure 4] FIG. 2 is a front view of the fixing device according to the first embodiment. [Figure 5] 1A and 1B are a cross-sectional view and a plan view of a heater according to a first embodiment. [Figure 6] 10 is a modified example of the heat conducting member according to the first embodiment. [Figure 7] FIG. 2 is a schematic diagram showing staples of a stapler and recording materials stapled together with the staples. [Figure 8] FIG. 10 is a perspective view showing a state in which a recording material is conveyed to a fixing device according to a conventional example. [Figure 9] FIG. 10 is a diagram showing how a heater according to a conventional example bends in the transport direction. [Figure 10] FIG. 10 is a cross-sectional view of a fixing device according to a conventional example. [Figure 11] FIG. 10 is a cross-sectional view of a fixing device according to a second embodiment. [Figure 12] FIG. 10 is a perspective view of a film unit and a heater according to a second embodiment. [Figure 13] 10A and 10B are a cross-sectional view and a plan view of a heater according to a second embodiment. [Figure 14] 10 is a modified example of the heater according to the second embodiment. [Figure 15]FIG. 10 is a cross-sectional view of a fixing device according to a modified example. [Figure 16] 10A and 10B are a cross-sectional view and a plan view of a heater according to a modified example. [Figure 17] FIG. 10 is a cross-sectional view of a fixing device according to a third embodiment. [Figure 18] 10A and 10B are schematic diagrams illustrating heat conduction members according to Example 3 and a modification thereof. [Figure 19] FIG. 10 is a cross-sectional view of a fixing device according to a fourth embodiment. [Figure 20] 10A and 10B are schematic diagrams showing heaters according to a fourth embodiment and a modification. DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes in detail, by way of example, the mode for carrying out the present invention with reference to the drawings. However, the dimensions, materials, shapes, and relative positions of the components described in the examples should be appropriately changed depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not intended to be limited to the following embodiments. Image forming devices to which the present invention can be applied include printers and copiers that use electrophotography or electrostatic recording methods, and the following description will be given of the application to a laser printer.

[0010] Example 1 (1) Image forming device 1 is a schematic diagram of an image forming apparatus 100 using electrophotographic recording technology in embodiment 1. First, the configuration and operation of the image forming apparatus 100 will be described.

[0011] The image forming operation in the image forming section of the image forming apparatus 100 will be described. When the image forming apparatus 100 receives a print command from an external device, the scanner unit 3 emits a laser beam Z corresponding to image information toward the photoconductor 1. The photoconductor 1, which has been charged to a predetermined polarity by the charging roller 2, is scanned by the laser beam Z, and an electrostatic latent image corresponding to the image information is formed on the surface of the photoconductor 1. The developer 4 then supplies toner to the photoconductor 1, and a toner image corresponding to the image information is formed on the photoconductor 1. The toner image on the photoconductor 1 moves to a transfer position formed by the photoconductor 1 and transfer roller 5 as the photoconductor 1 rotates in the direction of arrow R, and is transferred to a recording material P fed from a cassette 6 by a pickup roller 7. The surface of the photoconductor 1 that has passed the transfer position is cleaned by a cleaner 8.

[0012] The recording material P onto which the toner image has been transferred is subjected to a fixing process using heat and pressure in a fixing device 9 serving as a fixing unit. Thereafter, the recording material P is discharged onto a paper discharge tray 11 by a paper discharge roller 10.

[0013] (2) Fixing device Next, the configuration and operation of the fixing device 9 will be described. In this embodiment, a tensionless film heating type fixing device 9 is used as an example of a heating device. The fixing device 9 of this embodiment uses an endless belt-shaped (or cylindrical) heat-resistant film, and at least a portion of the circumferential length of the film is always tension-free (in a state where no tension is applied), and the film is rotationally driven by the rotational driving force of a pressure member.

[0014] Fig. 2 is a schematic cross-sectional view of the fixing device 9 of this embodiment, showing how two sheets of recording material P bound with staples H, bearing toner images T, are transported to the fixing device 9. Fig. 3(a) is an exploded perspective view of a film unit 20 used in the fixing device 9, and Fig. 3(b) is a perspective view of a heat conductive member 51. Fig. 4 is a front view of the fixing device 9 as seen from the transport direction of the recording materials.

[0015] The configuration of the fixing device 9 will be described with reference to Figure 2. The fixing device 9 of this embodiment has a rotatable cylindrical film 23 and a heating unit 50 that heats the film 23 in the internal space of the film 23. The heating unit 50 is made up of a heater 22, which is a heating element, and a heat conduction member 51 that is joined to the heater 22 and contacts the inner surface of the film 23 to transfer heat from the heater 22 to the film 23. The fixing device 9 also has a film guide 21 that supports the heater 22 and guides the rotation of the film 23, a reinforcing member 24 that reinforces the film guide 21, and a pressure roller 30 that forms a nip N with the heating unit 50 and the film guide 21 via the film 23.

[0016] The heater 22 has a ceramic substrate 22a in the shape of an elongated plate, a heating element 22b that generates heat when energized, and a protective layer 22c that protects the surface of the heating element 22b. The detailed configuration of the heater 22 will be described later.

[0017] Thermistor 25, which is a temperature detection member, is in contact with the surface of heater 22 that contacts film guide 21. Power supply to heating element 22b is controlled in accordance with the temperature detected by thermistor 25, and the temperatures of heater 22 and film 23 are managed.

[0018] The film 23 is a cylindrical rotating body. The thickness of the film 23 is preferably approximately 20 μm or more and 100 μm or less to ensure good thermal conductivity. When the film 23 is a single-layer film, the film base layer 23a is preferably made of a material such as PTFE (polytetrafluoroethylene), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether), or PPS. When the film 23 is a composite-layer film, the film base layer 23a is preferably made of a material such as PI (polyimide), PAI (polyamide imide), PEEK (polyether ether ketone), or PES (polyether sulfone). Furthermore, the film release layer 23b coated on the surface is preferably made of a material such as PTFE, PFA, or FEP (tetrafluoroethylene-perfluoroalkyl vinyl ether). Alternatively, a base layer made of a pure metal or alloy such as SUS, Al, Ni, Cu, or Zn with high thermal conductivity, and the release layer is preferably coated with the aforementioned coating or covered with a fluororesin tube, is also suitable.

[0019] The film 23 of this example is a composite layer film in which the film base layer 23a is made of PI with a thickness of 60 μm, and the film release layer 23b is coated with a film release layer 23b made of PFA with a thickness of 12 μm to balance abrasion caused by paper passing and thermal conductivity. The longitudinal length of the film 23 is 240 mm. The axial direction of the cylindrical shape of the film 23 is hereinafter referred to as the longitudinal direction.

[0020] The film guide 21 is provided in the internal space of the film 23 and is a support member that supports the heater 22 at a heater support portion 21a. The film guide 21 has a recess 21b that engages with a protrusion 51a of the film guide 21. The film 23 is loosely fitted onto the film guide 21, and the film guide 21 also functions as a guide to guide the rotation of the film 23 while making sliding contact with the inner peripheral surface of the film 23. Since the film guide 21 needs to be heat-resistant and rigid, it is preferable to use a liquid crystal polymer resin or the like, which has high heat resistance and excellent strength, as the material for the film guide 21. For example, a molded product of a heat-resistant resin such as PPS (polyphenylene sulfite) or liquid crystal polymer is used as the film guide 21.

[0021] The reinforcing member 24 is made of a metal such as iron, and receives the force of a pressure spring (described later) to press the heater 22 toward the pressure roller 30 via the film guide 21. Furthermore, the reinforcing member 24 is also a member for maintaining strength so that the film guide 21 does not deform significantly even under the pressure that forms the nip portion N.

[0022] The heat conductive member 51 is a member that is long in the longitudinal direction, and is preferably made of a material such as metal that has excellent thermal conductivity. As described above, the heat conductive member 51 constitutes the heater 22 and the heating unit 50 for heating the film 23. That is, the heating unit 50 heats the film 23 via the heat conductive member 51 using the heated heater 22. The heat conductive member 51 in this embodiment is bonded to the heater 22 with a heat conductive adhesive 60, and is in contact with the inner circumferential surface of the film 23.

[0023] The heat conductive member 51 is disposed so as to cover the entire area of ​​the substrate 22a in the short-side direction when viewed in the thickness direction of the substrate 22a. The heat conductive member 51 has a convex portion 51a bent into an L-shape at an end in the short-side direction, and the convex portion 51a protrudes away from the pressure roller 30 in the thickness direction of the substrate 22a from the heater 22. To engage with the concave portion 21b, the convex portion 51a is positioned so as not to overlap the substrate 22a or the heating element 22b when viewed in the thickness direction of the substrate 22a, and is located upstream of the heater 22 in the transport direction. Furthermore, the convex portion 51a, together with the concave portion 21b, is located downstream of the entrance of the nip portion N and upstream of the exit of the nip portion N in the transport direction. By inserting the convex portion 51a into the concave portion 21b provided in the film guide 21, the relative movement of the heating unit 50 in the transport direction with respect to the film guide 21 is restricted. In this embodiment, the thickness direction of the substrate 22a is approximately parallel to the pressure direction of the recording material P conveyed to the fixing device 9.

[0024] The pressure roller 30 is a rotating body having a core metal 30a made of a material such as iron or aluminum, an elastic layer 30b made of a material such as silicone rubber, and a release layer 30c made of a material such as PFA. The pressure roller 30 receives power from a motor M via a gear (not shown) to rotate in the direction b, and forms a nip N with the heating unit 50 and the film guide 21 via the film 23.

[0025] 2, as the pressure roller 30 rotates in the direction b, the film 23 rotates in the direction a following the movement of the pressure roller 30, and the heating unit 50 receives a force in the direction of arrow c, which is approximately parallel to the conveying direction of the recording material P. However, as described above, the convex portion 51a of the heat conductive member 51 is engaged with the concave portion 21b of the film guide 21, so the heating unit 50 does not move significantly in the direction c or bend within the heater support portion 21a. As the recording material P is nipped and conveyed in the nip portion N, the toner image T is heat-fixed to the recording material P, and the recording material P that has passed through the nip portion N is conveyed to the discharge tray 11.

[0026] Next, the film unit 20 of the fixing device 9 will be described with reference to the exploded perspective view of FIG. 3(a). The heater 22 and heat conductive member 51, joined with a thermally conductive adhesive, are held by the film guide 21 as the heating unit 50. After the film guide 21 and the reinforcing member 24 are fitted together, the film 23 is fitted around the outer periphery of the film guide 21 and the reinforcing member 24 with some circumferential leeway. Both ends of the reinforcing member 24 protrude beyond both ends of the film 23, and flanges 26 are fitted to each end. In this way, the film unit 20 is assembled, including the film 23, heating unit 50, film guide 21, flanges 26, etc.

[0027] A power supply terminal of the heater 22 protrudes from one longitudinal end of the film 23, and a power supply connector 27 is fitted into the power supply terminal. The power supply connector 27 comes into contact with the electrode portion of the heater 22 with a predetermined contact pressure, forming a power supply path. The heater clip 28 is a metal plate bent into a C-shape, and its springiness holds the end of the heater 22 against the film guide 21. That is, the heater 22 is held at both longitudinal ends located outside the paper passage area by the power supply connector 27 and the heater clip 28, which serve as holding members.

[0028] 3(b), the heat conduction member 51 has a length sufficient to cover the entire paper passage area in the width direction perpendicular to the conveyance direction of the recording material. In this embodiment, the width direction of the recording material is approximately parallel to the longitudinal direction of the film 23, etc. Furthermore, the protrusions 51a in this embodiment extend over the entire longitudinal area of ​​the heat conduction member 51. The heat conduction member 51 may be formed by bending a metal plate member, or it can be manufactured by other means such as cutting.

[0029] Next, the configuration of fixing device 9 will be described in more detail with reference to Fig. 4. Flanges 26 provided at both ends of film 23 restrict movement of film 23 in the longitudinal direction as it rotates and travels, and regulate the position of film 23 when fixing device 9 is operating.

[0030] The film unit 20 is disposed opposite the pressure roller 30 and is supported by the top panel-side housing 41. The film unit 20 is supported by the top panel-side housing 41 so that it can move freely in the pressure direction, and movement in the longitudinal direction is restricted. A pressure spring 45 is attached in a compressed state to the top panel-side housing 41 of the fixing device 9. The pressing force of the pressure spring 45 is received by both longitudinal ends of the reinforcing member 24 via the flanges 26. The pressing force of the pressure spring 45 presses the reinforcing member 24 toward the pressure roller 30, and the entire film unit 20 is pressed toward the pressure roller 30, forming a nip N.

[0031] The bearing member 31 is provided to pivotally support the core metal of the pressure roller 30, and receives the pressing force from the film unit 20 via the pressure roller 30. In order to rotatably support the core metal of the pressure roller 30, which becomes relatively hot, the bearing member 31 is made of a material that is heat resistant and has excellent sliding properties. The bearing member 31 is attached to the bottom housing 43 of the fixing device 9.

[0032] (3) Heater 22 Next, the materials constituting the heater 22 of this embodiment, the manufacturing method, etc. will be described with reference to Fig. 5. Fig. 5(a) is a cross-sectional view of the heater 22 seen from the longitudinal direction, and Fig. 5(b) is a plan view seen from the thickness direction of the substrate 22a.

[0033] (3-1) Substrate 22a The substrate 22a in this embodiment is a substrate made of ceramics. The type of ceramic is not particularly limited, and may be appropriately selected taking into consideration the required mechanical strength, the coefficient of linear expansion suited to the formation of the heating element, the ease of obtaining plate materials on the market, etc.

[0034] The thickness of the substrate 22a can be determined taking into consideration its strength, heat capacity, and heat dissipation performance. A thin substrate 22a has a small heat capacity, which is advantageous for quick start-up, but if it is too thin, distortion is likely to occur when the heating element is heated. Conversely, a thick substrate 22a is advantageous in terms of distortion when the heating element is heated, but if it is too thick, it has a large heat capacity, which is disadvantageous for quick start-up. The preferred thickness of the substrate 22a is 0.3 mm to 2.0 mm, taking into consideration the balance between mass productivity, cost, and performance. The substrate 22a in this embodiment is an alumina substrate with a width of 10 mm, a length of 300 mm, and a thickness of 1 mm.

[0035] (3-2) Heating element 22b Heating element 22b is formed by printing a heating element paste containing (A) a conductive component, (B) a glass component, and (C) an organic binder component on substrate 22a and then firing the paste. When the heating element paste is fired, the organic binder component (C) is burned away, leaving components (A) and (B), resulting in heating element 22b containing the conductive component and the glass component. Here, the conductive component (A) is preferably silver-palladium (Ag-Pd), ruthenium oxide (RuO), or the like, used alone or in combination, with a sheet resistance (surface resistivity) of 0.1 [Ω / □] to 100 [kΩ / □]. Materials other than those listed above (A) to (C) may also be included in trace amounts that do not impair the properties of the present invention.

[0036] The heating element 22b in this embodiment is formed from a heating element paste containing silver-palladium (Ag-Pd) as the conductive component, as well as a glass component and an organic binder component. The heating element paste is applied to the ceramic substrate 22a by screen printing, then dried at 180°C and fired at 850°C to form the heating element 22b. After firing, the heating element 22b has a thickness of 15 μm, a length of 220 mm, and a width of 1.1 mm.

[0037] (3-3) Power supply electrode 22d and conductive pattern 22e 5(b) are mainly made of silver (Ag), platinum (Pt), gold (Au), a silver-platinum (Ag-Pt) alloy, a silver-palladium (Ag-Pd) alloy, etc. The power supply electrode 22d and the conductive pattern 22e are formed by printing a paste, similar to the heating element paste, containing a mixture of (A) a conductive component, (B) a glass component, and (C) an organic binder component on the substrate 22a and then firing the paste.

[0038] Power supply electrode 22d and conductive pattern 22e are provided for the purpose of supplying power to heating element 22b, and their resistance is set sufficiently low compared to that of heating element 22b. For the heating element paste, power supply electrode, and conductive pattern paste, materials that soften and melt at a temperature lower than the melting point of substrate 22a and that are heat resistant in consideration of the temperatures in actual use must be selected.

[0039] In this example, power supply electrode 22 d and conductive pattern 22 e were formed using a paste for the power supply electrode and conductive pattern, which contained silver as the conductive component, a glass component, and an organic binder component mixed in. The paste for the power supply electrode and conductive pattern was applied to ceramic substrate 22 a by screen printing, and then dried at 180°C and fired at 850°C to form power supply electrode 22 d and conductive pattern 22 e.

[0040] (3-4) Protective layer 22c 5 is provided for the purpose of protecting the heating element 22b and the conductive pattern 22e. As a material, glass or PI (polyimide) is preferable from the viewpoint of heat resistance, and a thermally conductive filler having insulating properties may be mixed as needed.

[0041] In this example, a protective layer glass paste was prepared, and the protective layer glass paste was applied to the heating element 22b and the conductive pattern 22e by screen printing. After that, the paste was dried at 180°C and fired at 850°C to form a protective layer 22c with a thickness of 60 μm.

[0042] (4) Effects To explain the effects of the present invention, we will first explain the mechanism by which holes corresponding to the positions of the staples are made in the film, which is a flexible member, when a recording material bound with staples is transported to the fixing device.

[0043] 7(a) is a schematic diagram of a staple H for a stapler, and FIG. 7(b) is a schematic diagram showing two sheets of recording material P stapled together using the staple H. FIG. 8 shows the recording material P stapled together using the staple H in a conventional example. 7B is a schematic diagram showing the state in which recording material P is conveyed to and passed through a fixing device 109 having a film unit 120. When recording material P is stapled with staples H using a stapler, the staples H are attached to one side (side a) of the recording material P so as to follow the recording material P, and the staples H are bent to form protruding bent portions H1 on the other side (side b). When recording material P stapled with staples H shown in FIG. 7B is conveyed to the fixing device, holes W corresponding to the positions of the staples may be made in film 23, which is a flexible member, as shown in FIG. 8. In particular, when recording material P is conveyed so that side b, which is the side where the staples H are bent in FIG. 7B, comes into contact with film 23, the sharp bent portions H1 of the staples H pierce film 23, causing significant perforation in film 23. As a result, toner images T on recording material P corresponding to holes W in film 23 are not sufficiently heated and fixed, resulting in offset images U as shown in FIG. 8 and resulting in poor fixing.

[0044] The mechanism by which staples H of a stapler make holes in film 23 in fixing device 109 of the conventional example will be described in more detail with reference to Figures 9 and 10. Hereinafter, the same components as those in Example 1 will be denoted by the same reference numerals, and a description thereof will be omitted. Unlike this example, fixing device 109 of the conventional example shown in Figures 9 and 10 does not include heat conductive member 51, and film guide 121 does not have a recess. Therefore, in fixing device 109, film 23 slides in direct contact with heater 22.

[0045] FIG. 9(a) is a perspective view showing how recording material P bound with staples H is transported to a conventional fixing device 109, excluding the film 23 and pressure roller 30 so that the heater 22 can be seen. FIG. 9 shows a case in which the recording material P is transported with the bent side of the staples H, i.e., surface b, in contact with the film 23. FIG. 9(b) shows the initial state of the fixing device 109 in which no load is applied, with the heater 22 attached to the heater support portion 121a of the film guide 121 in region a of FIG. 9(a). As shown in FIG. 9(b), the heater support portion 121a is provided wider than the heater 22 to provide a gap S between the heater 22 and the heater 22, taking into consideration the expansion of the heater 22 due to heat generation. The heater 22 is held at both ends by a power supply connector 27 and a heater clip 28, but is not particularly held within the paper passage area through which the recording material P passes.

[0046] 9(c) shows how, as the film 23 rotates, the heater 22 in contact with the film 23 receives a force in the direction c from the film 23, causing the heater 22 to bend in the conveyance direction of the recording material P. At this time, a gap L is generated between the heater 22 and the heater support portion 121a on the upstream side of the heater 22 in the conveyance direction. Because the heater 22 is held at both ends in the longitudinal direction by the power supply connector 27 and the heater clip 28, the gap L is largest near the center of the heater 22 in the longitudinal direction.

[0047] 10(a) is a cross-sectional view of the longitudinal center of a conventional fixing device 109 when the heater 22 is not bent. FIG. 10(b) is a cross-sectional view of the longitudinal center of the fixing device 109 when the heater 22 is bent due to rotation of the film 23. The heater 22 is disposed within a heater support portion 121a of the film guide 121.

[0048] At the nip N, the needle H is subjected to pressure from the pressure roller 30, causing the needle H to be pushed into the gap L. At this time, the needle H rubs strongly against the hard and sharp corner of the heater 22, causing a hole to form in the film 23 sandwiched between them. Note that it is possible that the needle H may be pushed into the gap between the heater 22 and the heater support portion 21a, downstream of the heater 22 in the conveyance direction, but because the film guide 21 is not as hard and sharp as the heater 22, the possibility of a hole being formed in the film 23 is low. In the paper passing evaluation described below, no holes were formed in the film 23, even in a configuration in which there was a gap downstream of the heater 22 in the conveyance direction.

[0049] (4.1 Paper passing evaluation) Next, a paper passing evaluation conducted to confirm the effects of the present invention will be described. 7(b), two sheets of recording material P were stacked and stapled at three points at the leading edge with staples H, and 20 sheets were continuously passed through at a conveying speed of 200 mm / s to check for holes in the film 23 and the occurrence of image defects. In addition to the fixing device 9 of this embodiment, the paper passing evaluation was also performed on the fixing device 109 of the above-mentioned conventional example that does not have a heat conductive member as a comparison, and the results were compared.

[0050] As a result of evaluation using the fixing device 9 provided with the heat conductive member 51 of this embodiment, no holes were made in the film 23, and good fixed images were obtained on all evaluation papers.

[0051] As shown in FIG. 2, in this embodiment, the convex portion 51a of the heat conduction member 51 is inserted into the concave portion 21b of the film guide 21. Therefore, even if a force in the direction c acts on the heating unit 50, the relative movement of the heating unit 50 toward the downstream side in the transport direction with respect to the film guide 21 is restricted. Therefore, according to the present invention, a gap into which a needle H can enter is not formed between the heating unit 50 and the heater support portion 21a on the upstream side of the heating unit 50 in the transport direction, and holes in the film 23 can be prevented even when a recording material having a protrusion such as a needle H is transported. Note that when no load is applied to the heating unit 50, the convex portion 51a may or may not be in contact with the concave portion 21b from the beginning; it is sufficient that the configuration minimizes the gap between the heating unit 50 and the film guide 21.

[0052] As described above, the fixing device 109 of the conventional example does not have the heat conductive member shown in Fig. 10. The other image forming apparatus and fixing device have the same configuration as in the first embodiment, so their description will be omitted.

[0053] When a paper feed test similar to that in Example 1 was conducted using the conventional fixing device 109, a hole was made in the film 23, and an offset image U as shown in FIG. 8 was produced, resulting in a defective image. This is thought to be because the heater 22 received a force in the direction c from the film 23 and moved in the conveyance direction, as shown in FIG. 10(b). In other words, the needle H received a pressure from the pressure roller 30, and was pushed into the gap L between the heater 22 and the heater support part 121a, which was generated upstream of the heater 22 in the conveyance direction. As a result, the corners of the needle H and the heater 22 rubbed strongly against each other, and a hole was made in the film 23.

[0054] It should be noted that, to prevent holes from being made in the film as in this embodiment, it is not necessary for the protrusions 51a to extend over the entire length of the heat conduction member 51 (width direction of the recording material). As long as the protrusions 51a of the heat conduction member 51 are provided within the paper passage area of ​​the recording material P through which the needles H pass, the same effect as this embodiment can be expected. In particular, if the protrusions 51a are provided in the center in the length direction where the amount of deformation of the heater 22 is greatest, it is possible to effectively restrict the relative movement of the heating unit 50 downstream in the transport direction with respect to the film guide 21.

[0055] As described above, the present invention is not limited to the configuration of the first embodiment. As a modified example, a configuration in which the protrusions 52a are provided throughout the entire paper passage area, rather than the entire longitudinal area of ​​the heat conduction member 52, as in the heat conduction member 52 shown in FIG. 6( a), is also possible. Another modified example is a configuration in which multiple short protrusions 53a are provided within the paper passage area, as in the heat conduction member 53 shown in FIG. 6( b). Because the heat conduction member 52 has the protrusions 52a provided throughout the entire paper passage area, it has sufficient strength to withstand the force exerted by the rotation of the film 23. On the other hand, because the heat conduction member 53 has only three short protrusions 53a within the paper passage area, it is inferior in strength to the heat conduction member 52. However, from the perspective of minimizing the increase in heat capacity, the heat conduction member 53, which has a smaller volume than the heat conduction member 52, is superior. In other words, an appropriate configuration can be selected taking into consideration the strength required based on the pressure applied by the fixing device, the rotation speed of the film, the warm-up time required for the image forming apparatus, and the manufacturing cost of the heat conduction member.

[0056] In this embodiment, the convex portion 51a is positioned upstream of the heater 22 in the transport direction. However, other variations are possible, such as a configuration in which the convex portion is positioned downstream in the transport direction or both upstream and downstream. Alternatively, a configuration in which the convex portion extends toward the pressure roller in the pressure direction, rather than away from the pressure roller, is also possible. Furthermore, the convex portion does not necessarily have to extend perpendicular to the surface of the recording material. It can also extend at a predetermined angle relative to the pressure direction, as long as it restricts downstream movement of the heating unit in the transport direction. In other words, as long as the heating unit and heater holder have engaging and engaged portions that restrict relative movement of the heating unit with respect to the heater holder, the same film perforation prevention effect can be achieved regardless of whether the convex or concave portion is used.

[0057] <Example 2> Next, a second embodiment of the present invention will be described. A fixing device 209 of the second embodiment does not have a heat conductive member, and a convex portion that engages with a concave portion of the film guide is provided on a heater substrate. In the following, the same components as those of the first embodiment will be assigned the same reference numerals, and a description thereof will be omitted.

[0058] Fig. 11 is a schematic cross-sectional view of the fixing device 209 of this embodiment, showing how two sheets of recording material P bound with staples H, bearing toner images T, are conveyed to the fixing device 209. Fig. 12(a) is an exploded perspective view of a film unit 220 used in the fixing device 209, and Fig. 12(b) is a perspective view of a heater 222 having a protrusion 222f.

[0059] The fixing device 209 according to the second embodiment differs from the fixing device 9 according to the first embodiment in that it does not have a heat conductive member and that the heater 222 has a protrusion 222f that engages with the recess 221b of the film guide 221. In other words, the heating unit according to the second embodiment is composed solely of the heater 222. Descriptions of other components of the image forming apparatus and fixing device similar to those of the first embodiment will be omitted.

[0060] Next, the materials constituting the heater 222 of this example, the manufacturing method, etc. will be described with reference to Fig. 13. Fig. 13(a) is a cross-sectional view of the heater 222 seen from the longitudinal direction, and Fig. 13(b) is a plan view seen from the thickness direction of the substrate 222a.

[0061] In this embodiment, the substrate 222a of the heater 222 is made of metal, and may be primarily made of at least a metal alloy. The heater 222 includes a long, thin, plate-shaped substrate 222a, a heating element 222b that generates heat when power is applied, an insulating layer 222g that insulates the heating element 222b from the substrate 222a, and a protective layer 222c that protects the heating element. To prevent warping of the substrate during manufacturing, an insulating layer 222h is also provided on the surface of the substrate 222a opposite to the surface on which the heating element 222b is provided. In this embodiment, the heating element 222b is provided on the substrate 222a via the insulating layer 222g.

[0062] The substrate 222a is provided with a convex portion 222f formed by bending the upstream end of the substrate 222a in the transport direction. The convex portion 222f is located upstream of the heating element 222b and the insulating layer 222h in the transport direction, and extends so as to protrude further away from the pressure roller 30 than the insulating layer 222h in the thickness direction of the substrate 222a. Meanwhile, the concave portion 221b provided in the film guide 221 is recessed in the thickness direction of the substrate 222a on the side away from the pressure roller 30, and engages with the convex portion 222f. In this embodiment, the thickness direction of the substrate 222a is approximately parallel to the pressure direction of the recording material P transported to the fixing device 209.

[0063] Suitable materials for the metal substrate 222a include stainless steel, nickel, copper, aluminum, and alloys containing these as the main material. Among these, stainless steel is preferred for its strength and It is most preferable from the viewpoint of heat resistance and corrosion. The type of stainless steel is not particularly limited, and may be appropriately selected taking into consideration the required mechanical strength, the coefficient of linear expansion suitable for forming the insulating layer and heating element described below, ease of availability of the plate material in the market, etc. As an example, martensitic and ferritic chromium-based stainless steel (400 series) is preferably used because it has a relatively low coefficient of linear expansion among stainless steels and is easy to form the insulating layer and heating element.

[0064] The thickness of the substrate 222a can be determined taking into consideration its strength, heat capacity, and heat dissipation performance. A thin substrate 222a has a small heat capacity, which is advantageous for quick start-up; however, if it is too thin, distortion is likely to occur when the heating element 222b is heated. Conversely, a thick substrate 222a is advantageous in terms of distortion when the heating element 222b is heated, but if it is too thick, it has a large heat capacity, which is disadvantageous for quick start-up. The preferred thickness of the substrate 222a is approximately 0.3 mm to 2.0 mm, taking into consideration the balance between mass productivity, cost, and performance. The substrate 222a in this embodiment is a ferritic stainless steel substrate (SUS430: 18Cr stainless steel) with a width of 10 mm, a length of 300 mm, and a thickness of 0.5 mm.

[0065] Next, the insulating layers 222g and 222h will be described. While the material for the insulating layers 222g and 222h is not particularly limited, a heat-resistant material must be selected taking into account the actual operating temperature. Glass and PI (polyimide) are preferred materials from the perspective of heat resistance. When using glass, the powder material may be selected appropriately within a range that does not impair the characteristics of the present invention from the perspective of heat resistance, etc. Furthermore, if necessary, a thermally conductive filler with insulating properties may be mixed. The insulating layers 222g and 222h may be made of the same material or different materials. Regarding the layer thickness, the insulating layers 222g and 222h may have the same thickness or different thicknesses. Generally, a heater used in an image forming apparatus preferably has a dielectric strength of approximately 1.5 kV. Therefore, the thickness of the insulating layer 222g can be determined depending on the material in order to obtain a dielectric strength of 1.5 kV between the heating element 222b and the substrate 222a. The method for forming the insulating layers 222g and 222h is not particularly limited, but as an example, they can be formed smoothly by screen printing, etc. When forming an insulating layer of glass or PI (polyimide) on the substrate 222a, it is necessary to appropriately adjust the linear expansion coefficients of the substrate and the insulating layer material so that cracks or peeling do not occur in the insulating layer due to differences in the linear expansion coefficients between the materials.

[0066] In this example, insulating layer glass paste was applied by screen printing to the aforementioned stainless steel substrate 222a, and then the substrate was dried at 180° C. and fired at 850° C. to form insulating layer 222g having a thickness of 60 μm and insulating layer 222h having a thickness of 120 μm. The methods for forming heating element 222b, power supply electrode 222d, conductive pattern 222e, and protective layer 222c on substrate 222a on which insulating layers 222g and 222h were formed were the same as in Example 1, and therefore will not be described again.

[0067] The effects of this embodiment will be described using Figure 11. In this embodiment, the convex portion 222f of the heater 222 is inserted into the concave portion 221b of the film guide 221. Therefore, even if a force in the direction c acts on the heater 222, the relative movement of the heater 222 toward the downstream side in the transport direction with respect to the film guide 221 is restricted. Therefore, according to the present invention, a gap into which a needle H could get caught is not generated between the heater 222 and the heater support portion 221a on the upstream side of the heater 222 in the transport direction, and holes in the film 23 can be prevented even when a recording material having a protrusion such as a needle H is transported.

[0068] Using the fixing device 209 of this embodiment, a paper feed test similar to that of Example 1 was conducted, and as a result, no holes were made in the film 23, and good fixed images were obtained on all evaluation papers. Furthermore, since the heat conductive member 51 is not provided in this embodiment, there is no increase in heat capacity compared to Example 1, and the warm-up time of the fixing device 209 can be improved.

[0069] The present invention is not limited to the above-mentioned configuration. As a modified example, for example, the configuration shown in FIG. As in the heater 223 shown in FIG. 14B, the heater 223 may have a configuration in which the convex portions 223f are provided throughout the entire paper passage area, rather than across the entire longitudinal area of ​​the heater 223. As another variation, as in the heater 224 shown in FIG. 14B, the heater 223 may have a configuration in which multiple convex portions 224f with short longitudinal lengths are provided within the paper passage area. Because the heater 223 has convex portions 223f provided throughout the paper passage area, it has sufficient strength to withstand the force exerted by the rotation of the film 23. On the other hand, the heater 224 has convex portions 224f with short longitudinal lengths provided in three locations within the paper passage area, making it inferior to the heater 223 in terms of strength. However, from the perspective of minimizing the increase in heat capacity, the heater 224, which has a smaller volume than the heater 223, is superior. In other words, the necessary configuration can be selected appropriately taking into consideration the strength required based on the pressure force of the fixing device, the rotation speed of the film, etc., the warm-up time required for the image forming apparatus, the manufacturing cost of the heater, etc.

[0070] As other variations, although the convex portion 222f in this embodiment is configured to be located upstream of the heater 222 in the transport direction, a configuration in which the convex portion is located downstream in the transport direction or a configuration in which the convex portion is located on both the upstream and downstream sides is also conceivable. Another example of a variation is a configuration in which the convex portion extends toward the pressure roller in the pressure direction, rather than away from the pressure roller. Furthermore, the convex portion does not necessarily have to extend perpendicular to the surface of the recording material; even if the convex portion extends at a predetermined angle with respect to the pressure direction, it is sufficient as long as the configuration restricts movement of the heater downstream in the transport direction.

[0071] Furthermore, other modified examples include a configuration in which a heat conduction member having a protrusion is provided on a metal substrate, or a configuration in which a protrusion is provided on a ceramic substrate. A modified example in which a heat conduction member 551 having a protrusion 551a is provided on a metal substrate 522a will be described using Figures 15 and 16. Hereinafter, in the configuration of the modified example, the same components as those in Example 1 will be assigned the same reference numerals, and description thereof will be omitted.

[0072] 15 is a schematic cross-sectional view of a fixing device 509 according to a modified example. Fixing device 509 has a configuration in which a heat conductive member 551 having a protrusion 551a is joined to a heater 522, as in Example 1. When heater 522 is attached to heater attachment portion 521a of film guide 521, protrusion 551a of heat conductive member 551 engages with recess 521b of film guide 521, restricting relative movement of heater 522 with respect to film guide 521 in the conveyance direction.

[0073] FIG. 16(a) is a cross-sectional view of the heater 522 viewed from the longitudinal direction, and FIG. 16(b) is a plan view of the substrate 522a viewed from the thickness direction. In this embodiment, the substrate 522a of the heater 522 is made of metal, and may be primarily made of at least a metal alloy. The heater 522 includes a long, thin plate-shaped substrate 522a, a heating element 522b that generates heat when current is applied, an insulating layer 522g that insulates the heating element 522b from the substrate 522a, and a protective layer 522c that protects the heating element. To prevent warping of the substrate during manufacturing, an insulating layer 522h is also provided on the surface of the substrate 522a opposite to the surface on which the heating element 522b is provided. In this embodiment, the heating element 522b is provided on the substrate 522a via the insulating layer 522g.

[0074] Example 3 Next, a third embodiment of the present invention will be described. In a fixing device 309 of the third embodiment, a film guide 321 has a protrusion 321b, and a recess 351a provided in a heat conduction member 351 of a heating unit 350 engages with the protrusion 321b. Hereinafter, in the configuration of the third embodiment, the same components as those in the first embodiment are designated by the same reference numerals, and a description thereof will be omitted.

[0075] 17 is a schematic cross-sectional view of the fixing device 309 of this embodiment, showing how two sheets of recording material P bound with staples H, carrying toner images T, are conveyed to the fixing device 309. In this embodiment, the heating unit 350 includes a heater 22 and a heat conductive member 350 having the same configuration as in the first embodiment. It consists of 51.

[0076] The heat conductive member 351 in this embodiment has a recess 351a. The recess 351a is located upstream of the heater 22 in the conveying direction within the heating unit 350, and is recessed toward the pressure roller 30 in the thickness direction of the substrate 22a. Meanwhile, the protrusion 321b provided on the film guide 321 extends toward the pressure roller 30 in the thickness direction of the substrate 22a and engages with the recess 351a. As shown in FIG. 18(a), the heat conductive member 351 in this embodiment has the recess 351a formed over the entire length. In this embodiment, the thickness direction of the substrate 22a is approximately parallel to the pressure direction of the recording material P conveyed to the fixing device 309.

[0077] Due to the engagement between recessed portion 351a and protruding portion 321b, even if a force in direction c acts on heating unit 350, the relative movement of heating unit 350 downstream in the transport direction with respect to film guide 321 is restricted. Therefore, according to the present invention, no gap into which needle H can get caught is generated between heating unit 350 and heater support portion 321a on the upstream side of heating unit 350 in the transport direction, and holes in film 23 can be prevented even when a recording material having protrusions such as needle H is transported.

[0078] Using the fixing device 309 of this embodiment, a paper feed test similar to that of Example 1 was conducted. As a result, no holes were made in the film 23, and good fixed images were obtained on all evaluation sheets. Furthermore, in this embodiment, the heat conductive member 351 has recesses 351a instead of protrusions, and therefore has a smaller volume and heat capacity than the heat conductive member 51 of Example 1. Therefore, in this embodiment, the heat capacity of the heat conductive member is reduced compared to Example 1, and the warm-up time of the fixing device can be improved.

[0079] The present invention is not limited to the above-described configuration. For example, a configuration in which recesses 352a are provided throughout the entire paper passage area, rather than throughout the entire longitudinal area of ​​the heat conduction member 352, as in the heat conduction member 352 shown in FIG. 18(b). Another configuration in which multiple recesses 353a with short longitudinal lengths are provided within the paper passage area, as in the heat conduction member 353 shown in FIG. 18(c), may be used. Because the heat conduction member 352 has recesses 352a provided throughout the entire paper passage area, it has sufficient strength to withstand the force exerted by the rotation of the film 23. On the other hand, because the heat conduction member 353 has three recesses 353a with short longitudinal lengths provided within the paper passage area, it is inferior in strength to the heat conduction member 352. However, from the perspective of minimizing the increase in heat capacity, the heat conduction member 353, which has a smaller volume than the heat conduction member 352, is superior. Furthermore, when the recesses are formed by cutting, heat conductive member 353, which has a shorter recess, is more cost-effective to process than heat conductive member 351 or heat conductive member 352. In other words, the required configuration can be selected appropriately, taking into consideration the pressure applied by the fixing device, the strength required based on the rotation speed of the film, the warm-up time required for the image forming apparatus, the manufacturing cost of the heating unit, and the like.

[0080] Other possible modifications include a configuration in which the recess is provided downstream of the heater in the transport direction, a configuration in which the recess is provided both upstream and downstream, and a configuration in which the substrate is made of metal instead of ceramic.

[0081] Example 4 Next, a fourth embodiment of the present invention will be described. Similar to the second embodiment, the fixing device 409 of the fourth embodiment does not have a heat conductive member. Furthermore, in the fixing device 409 of the fourth embodiment, the film guide 421 has a protrusion 421b, and a recess 422d provided on a substrate 422a of the heater 422 engages with the protrusion 421b. Hereinafter, in the configuration of the fourth embodiment, the same components as those of the first embodiment are designated by the same reference numerals, and the description thereof will be omitted.

[0082] 19 is a schematic cross-sectional view of the fixing device 409 of this embodiment, showing how two sheets of recording material P bound with staples H, carrying toner images T, are conveyed to the fixing device 409. In this embodiment, the heating unit does not have a heat conductive member and is composed only of a heater 422.

[0083] The heater 422 in this embodiment has a metal substrate 422a, a heating element 422b, a protective layer 422c, and insulating layers 422e and 422f. Furthermore, a recess 422d is formed near the upstream end of the substrate 422a in the transport direction, upstream of the heating element 422b and insulating layer 422f in the transport direction. The recess 422d is recessed toward the pressure roller 30 in the pressure direction (thickness direction of the substrate 422a). Meanwhile, a protrusion 421b provided on the film guide 421 extends toward the pressure roller 30 in the pressure direction and engages with the recess 422d. As shown in FIG. 20(a), the heater 422 in this embodiment has a recess 422d formed over the entire longitudinal direction. This forms a recess 422d.

[0084] Due to the engagement between recessed portion 422d and protruding portion 421b, even if a force in direction c acts on heater 422, the relative movement of heater 422 downstream in the transport direction with respect to film guide 421 is restricted. Therefore, according to the present invention, a gap into which needle H can get caught is not generated between heater 422 and heater support portion 421a on the upstream side of heater 422 in the transport direction, and holes in film 23 can be prevented even when a recording material having protrusions such as needle H is transported.

[0085] Using the fixing device 409 of this embodiment, a paper feed test similar to that of Example 1 was conducted, and as a result, no holes were made in the film 23, and good fixed images were obtained on all evaluation sheets. Furthermore, in this embodiment, the substrate 422a of the heater 422 is provided with recesses 422d instead of protrusions, so the heater 422 of this embodiment has a smaller volume and heat capacity than the heater 222 of Example 2. Therefore, in this embodiment, the heat capacity of the heater is reduced compared to Example 2, and the warm-up time of the fixing device can be improved.

[0086] The present invention is not limited to the above-described configuration. For example, a configuration in which the recesses 423d are provided throughout the entire paper passage area, rather than across the entire longitudinal area of ​​the heater 423, as in the heater 423 shown in FIG. 20(b). Another configuration in which multiple recesses 424d with short longitudinal lengths are provided within the paper passage area, as in the heater 424 shown in FIG. 20(c), may be used. Because the recesses 423d are provided throughout the entire paper passage area, the heater 423 has sufficient strength to withstand the force exerted by the rotation of the film 23. On the other hand, because the heater 424 has three recesses 424d with short longitudinal lengths provided within the paper passage area, it is inferior to the heater 423 in terms of strength. However, from the perspective of minimizing the increase in heat capacity, the heater 424, which has a smaller volume than the heater 423, is superior. Furthermore, when forming the recesses by cutting, the heater 424, which has short recesses, is more cost-effective than the heaters 422 and 423. That is, the required configuration can be selected appropriately taking into consideration the pressure force of the fixing device, the strength required from the rotation speed of the film, the warm-up time required for the image forming apparatus, the manufacturing cost of the heating unit, and the like.

[0087] Other examples of modifications include a configuration in which a recess is provided on the downstream side of the heating element in the transport direction, a configuration in which a recess is provided on both the upstream and downstream sides, a configuration in which the substrate is made of ceramic instead of metal, etc. Furthermore, it is also possible to combine multiple of the above-mentioned embodiments, and various configurations are possible, such as a configuration in which both a protrusion and a recess are provided on each of the heating unit and the film guide. [Explanation of symbols]

[0088] 9...heating device, 21...film guide (supporting member), 21b...recessed portion (engaged portion), 23...film, 30...pressure roller (rotating body), 50...heating unit, 51a...protruding portion (engaging portion) ), N...nip portion, P...recording material

Claims

1. A rotatable cylindrical film; a heating unit including a heater provided in an internal space of the film for heating the film and a heat-conducting member in contact with an inner circumferential surface of the film to transfer heat from the heater to the film; a support member that holds the heating unit and contacts an inner circumferential surface of the film to guide the rotation of the film; a rotating body that forms a nip portion between the rotating body and the film; Equipped with In the heating device that heats the recording material at the nip portion, the support member has an engaging portion located within a paper passing area in a width direction of the recording material that is perpendicular to a conveyance direction of the recording material, the heat conduction member has an engaged portion that engages with the engaging portion, the engaging portion engages with the engaged portion, thereby determining a position of the heating unit in the transport direction relative to the support member; The heating device according to claim 1, wherein the engaging portion and the engaged portion are located downstream of an entrance of the nip portion and upstream of an exit of the nip portion in the conveying direction.

2. 2. The heating device according to claim 1, further comprising holding members positioned outside a paper passing area and holding both ends of the heating unit in the width direction so as to restrict relative movement of the heating unit with respect to the support member.

3. the engaging portion is a protruding portion, the engaged portion is a recess, 3. The heating device according to claim 1, wherein the convex portions protrude in a direction perpendicular to the transport direction so as to overlap the concave portions when viewed in the transport direction.

4. 4. The heating device according to claim 1, wherein the engaging portion is provided at the center in the width direction in the paper passing area.

5. 5. The heating device according to claim 1, wherein a plurality of the engagement portions are provided within the paper passage area.

6. 6. The heating device according to claim 5, wherein the heat conduction member is joined to the heater so as to cover the entire area of ​​the heater in the short side direction when viewed in the conveying direction and a pressure direction perpendicular to the width direction.

7. the engaging portion extends in a direction perpendicular to the surface of the conveyed recording material and toward the rotating body; 7. The heating device according to claim 1, wherein the engaged portion is provided at an upstream end of the heat conducting member in the transport direction.

8. A rotatable cylindrical film; a heater provided in an internal space of the film for heating the film, the heater including a substrate, a heating element provided on the substrate, and a protective layer covering the heating element, the heating element generating heat when energized; a support member that holds the heater and contacts an inner circumferential surface of the film to guide the rotation of the film; a rotating body that forms a nip portion between the rotating body and the film; Equipped with In the heating device that heats the recording material at the nip portion, the heater has an engagement portion located within a paper passing region in a width direction of the recording material that is perpendicular to a conveyance direction of the recording material, the support member has an engaged portion that engages with the engaging portion at an end portion on the upstream side in the conveying direction, the engaging portion engages with the engaged portion, thereby determining the position of the heater in the transport direction relative to the support member; The heating device according to claim 1, wherein the engaging portion and the engaged portion are located downstream of an entrance of the nip portion and upstream of an exit of the nip portion in the conveying direction.

9. The heating device according to claim 8, wherein the engaging portion is provided at an upstream end of the substrate in the transport direction and extends in a direction perpendicular to the surface of the transported recording material and away from the rotating body.

10. the substrate is an elongated plate member, 10. The heating device according to claim 8, wherein the engaging portion is formed by bending the plate member.

11. A rotatable cylindrical film; a heater provided in an internal space of the film for heating the film, the heater including a substrate, a heating element provided on the substrate, and a protective layer covering the heating element, the heating element generating heat when energized; a support member that holds the heater and contacts an inner circumferential surface of the film to guide the rotation of the film; a rotating body that forms a nip portion between the rotating body and the film; Equipped with In the heating device that heats the recording material at the nip portion, the support member has an engaging portion located within a paper passing area in a width direction of the recording material that is perpendicular to a conveyance direction of the recording material, the heater has an engaged portion that engages with the engaging portion, the engaging portion engages with the engaged portion, thereby determining the position of the heater in the transport direction relative to the support member; The heating device according to claim 1, wherein the engaging portion and the engaged portion are located downstream of an entrance of the nip portion and upstream of an exit of the nip portion in the conveying direction.

12. the engaging portion extends in a direction perpendicular to the surface of the conveyed recording material and toward the rotating body; 12. The heating device according to claim 11, wherein the engaged portion is provided at an upstream end of the substrate in the transport direction.

13. an image forming section for forming an image on a recording material; a fixing section that fixes the image formed on the recording material to the recording material; In an image forming apparatus having An image forming apparatus, wherein the fixing unit is the heating device according to any one of claims 1 to 12.

Images