Fixing device and image forming apparatus

Abstract

To obtain stable fixing performance over a long period.SOLUTION: A fixing device heats and fixes an image on a recording material with a first rotating body heated by a heater, while sandwiching and conveying the recording material between the first rotating body and a second rotating body at a nip part. A holder member holding the heater is provided on the side of the second rotating body in a thickness direction perpendicular to both a longitudinal direction and a short direction of the heater at the nip part, and has a first surface that supports the heater, a second surface that is provided on the opposite side of the first surface in the thickness direction and supported by a support member on the upstream side and the downstream side of the first surface in the short direction, and rib parts that are provided projected on the second surface and extend in the short direction over a range in which at least the first surface is provided with respect to the short direction.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a fixing device that fixes an image on a recording material and an image forming apparatus that forms an image on a recording material. [Background technology]

[0002] Image forming apparatuses such as electrophotographic image forming apparatuses are equipped with a thermal fixing type fixing device that heats and fixes a toner image transferred onto a recording material. Patent Document 1 describes a film heating type fixing device having a heater in which a resistance heating element is formed on a ceramic substrate, a holder member that holds the heater, a cylindrical film fitted onto the heater, and a pressure roller that is pressed against the heater with the film sandwiched between them. The above document also describes that the film is efficiently heated by dispersing particles with low thermal conductivity in the holder member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-102150 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the fixing device is used for a long period of time, the holder member may creep and deform due to continuous heat and load. For example, when the holder member creeps and deforms in the configuration described in the above document, the rotational trajectory of the film rotating around the holder member may change, and the contact area between the film and the heater may decrease, resulting in a deterioration in fixing performance.

[0005] SUMMARY OF THE PRESENT DISCLOSURE In view of the above, an object of the present invention is to provide a fixing device capable of achieving stable fixing performance over a long period of time, and an image forming apparatus including the same. [Means for solving the problem]

[0006] One aspect of the present disclosure is a method for manufacturing a printer comprising: a first rotating body; an elongated heater; and a holder member for holding the heater; a nip forming unit disposed in an internal space of the first rotating body; a detection element for generating a signal corresponding to a temperature of the heater; a second rotating body that is pressed against the nip forming unit across the first rotating body to form a nip portion between the second rotating body and the nip forming unit; The above a support member disposed in an internal space and supporting the nip forming unit, and the first rotating body heated by the heater heats and fixes an image on the recording material while the first rotating body and the second rotating body sandwich and transport the recording material at the nip portion, the holder member having a first surface that is disposed on the second rotating body side in a thickness direction perpendicular to both the longitudinal direction and the lateral direction of the heater at the nip portion and supports the heater, a second surface that is disposed on the opposite side of the first surface in the thickness direction and faces the support member, and a rib portion that is protruded from the second surface and extends in the lateral direction at least over a range in which the first surface is disposed, the holder member has a hole that penetrates from the first surface to the second surface, the detector element is disposed in the hole, and the rib portions are provided on both sides of the hole in the longitudinal direction. ,child The fixing device is characterized by the above. Another aspect of the present disclosure is a fixing device including a first rotating body, an elongated heater, and a holder member that holds the heater, the first rotating body having a nip forming unit disposed in an internal space of the first rotating body, a second rotating body that is pressed against the nip forming unit across the first rotating body to form a nip portion between the nip forming unit, and a support member that is disposed in the internal space of the first rotating body and supports the nip forming unit, the first rotating body heated by the heater heats and fixes an image on the recording material while the first rotating body and the second rotating body sandwich and transport the recording material at the nip portion, the holder member having a first surface facing the second rotating body in a vertical direction perpendicular to both the longitudinal direction of the heater and the transport direction of the recording material at the nip portion, the first surface supporting the heater, and a second surface facing the opposite side of the first surface in the vertical direction, the second surface facing the support member, a downstream guide portion provided on the holder member in the transport direction and extending toward the opposite side of the second rotating body in the perpendicular direction to the second surface, the upstream guide portion guiding the inner surface of the first rotating body toward the nip portion; and a downstream guide portion provided on the holder member in the transport direction and extending toward the opposite side of the second rotating body in the perpendicular direction to the second surface, the downstream guide portion guiding the inner surface of the first rotating body that has passed through the nip portion; and a rib portion protruding from the second surface, extending over a range including the range in which the first surface is provided in the transport direction, and extending from the upstream guide portion to the downstream guide portion, wherein the holder member has a hole penetrating from the first surface to the second surface, the hole in which a detector element for detecting the temperature of the heater is disposed, and the rib portion is provided on both sides of the hole in the longitudinal direction. Effect of the Invention

[0007] According to the present disclosure, stable fixing performance can be obtained over a long period of time. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to a first embodiment. [Diagram 2] 1A and 1B are schematic diagrams of a fixing device according to a first embodiment. [Diagram 3] FIG. 4 is a diagram for explaining a crown shape of the heater holder according to the first embodiment. [Figure 4] 5A and 5B are diagrams illustrating the shape of an opening of a heater holder according to the first embodiment. [Diagram 5] FIG. 2 is a cross-sectional view of the heater holder according to the first embodiment. [Figure 6] FIG. 4 is a view showing a rib portion of the heater holder according to the first embodiment. [Figure 7] FIG. 3 is a cross-sectional view of a portion having a rib portion of the heater holder according to the first embodiment. [Figure 8] 5A and 5B are diagrams for explaining stress acting on a heater holder. [Figure 9] FIG. 11 is a cross-sectional view of a heater holder in a reference example. [Figure 10] FIG. 11 is a perspective view showing a part of a heater holder according to a second embodiment. [Figure 11] 6A to 6C are cross-sectional views of a fixing device according to modified examples. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. EXAMPLES

[0010] (Image forming device) An image forming apparatus according to a first embodiment (Example 1) will be described with reference to the schematic diagram shown in Fig. 1. The image forming apparatus 50 in this example is a direct transfer type electrophotographic apparatus in which a toner image formed on a photosensitive drum 1 is directly transferred (i.e., without the intermediate transfer body) onto a recording material P.

[0011] The image forming apparatus 50 includes an electrophotographic unit including a photosensitive drum 1, a charger 2, an exposure device 3, a developing device 5, a transfer roller 10, and a drum cleaner 16 as an image forming means. The photosensitive drum 1, which is an image carrier, is an electrophotographic photosensitive member formed in a drum shape (cylindrical shape). The charger 2, the exposure device 3, the developing device 5, the transfer roller 10, and the drum cleaner 16 are arranged around the photosensitive drum 1 in this order along the rotation direction of the photosensitive drum 1 (the direction of the arrow R1).

[0012] When an image formation request is input to the image forming apparatus 50 from an external computer, the photosensitive drum 1 is rotationally driven in the direction of arrow R1, and the surface of the photosensitive drum 1 is charged to a predetermined polarity (negative polarity in this case) by the charger 2. Next, the charged surface of the photosensitive drum 1 is irradiated with laser light L from the exposure device 3, and an electrostatic latent image is formed on the surface of the photosensitive drum 1. The developing device 5 contains black toner, which is the developer in this embodiment, and supplies the negatively charged black toner to the photosensitive drum 1 by the developing roller. As a result, the toner adheres to the electrostatic latent image area on the photosensitive drum 1, and a toner image is formed on the surface of the photosensitive drum 1.

[0013] A feed tray on which recording material P is loaded is provided at the bottom of the image forming apparatus 50. As the recording material P, various sheet materials of different sizes and materials can be used, including paper such as plain paper and thick paper, sheet materials with surface treatments such as plastic film, cloth, and coated paper, and sheet materials with special shapes such as envelopes and index paper.

[0014] The recording materials P loaded on the feed tray are fed one by one by a feed roller 4 and conveyed via a conveying roller 6 to a transfer nip Ntr as a transfer section where a toner image is transferred to the recording material P. The transfer nip Ntr is a nip between the photosensitive drum 1 and a transfer roller 10. A voltage of positive polarity, which is opposite to the normal charging polarity of the toner, is applied to the transfer roller 10 from a power source (not shown), so that the toner image on the photosensitive drum 1 is transferred to the recording material P at the transfer nip Ntr. Any residual toner or paper powder adhering to the surface of the photosensitive drum 1 that has passed through the transfer nip Ntr is removed by a drum cleaner 16 having an elastic blade.

[0015] The recording material P onto which the toner image has been transferred is conveyed to a fixing device 100 of a thermal fixing type, which will be described below, and is subjected to a fixing process of the toner image. The recording material P that has passed through the fixing device 100 is discharged as a product to the outside of the image forming apparatus 50 by a pair of discharge rollers.

[0016] In this embodiment, a direct transfer type image forming apparatus is exemplified, but other types of image forming apparatuses may be used as long as they are equipped with a fixing device that heats and fixes a toner image formed on a recording material P. For example, the fixing device described below may be applied to an intermediate transfer type image forming apparatus in which a toner image formed on an image carrier is primarily transferred to an intermediate transfer body such as an intermediate transfer belt, and then the toner image is transferred from the intermediate transfer body to a recording material. Also, the fixing device described below may be applied to an image forming apparatus that forms a color image on a recording material using toners of multiple colors.

[0017] (Fixing device) The fixing device 100 of this embodiment will be described with reference to Figs. 2(a) and 2(b). The fixing device 100 of this embodiment is a film heating type fixing device that is excellent in terms of shortening the warm-up time and reducing power consumption. Fig. 2(a) is a cross-sectional view of the center of the fixing device 100 in the longitudinal direction. Fig. 2(b) is a cross-sectional view of the fixing device 100 along the longitudinal direction, showing only both ends of the fixing device 100 in the longitudinal direction.

[0018] In the following description, the shapes and positional relationships of the members in the fixing device 100 will be described using the recording material transport direction A, the longitudinal direction B, and the vertical direction C. The recording material transport direction A is the direction in which the recording material P is transported in the fixing nip Nf, which is the nip portion of the fixing device 100. The longitudinal direction B is the width direction of the recording material P in the fixing nip Nf (a direction perpendicular to the recording material transport direction A). The longitudinal direction B is also the main scanning direction during image formation. The vertical direction C is a direction perpendicular to both the recording material transport direction A and the longitudinal direction B.

[0019] 2(a, b), the fixing device 100 has a film unit 101 (film assembly) including a fixing film 112, a heater 113, a heater holder 130, and a pressure stay 119, and a pressure roller 110 facing the film unit 101. The fixing film 112, the heater 113, the heater holder 130, the pressure stay 119, and the pressure roller 110 are all members that are elongated in a longitudinal direction B. That is, the longitudinal direction B of the fixing device 100 is also the longitudinal direction of the fixing film 112, the heater 113, the heater holder 130, the pressure stay 119, and the pressure roller 110. The recording material conveying direction A is also the short side direction of the heater 113, and the vertical direction C is also the thickness direction of the heater 113.

[0020] The heater holder 130 is a holder member or a holding member in this embodiment. The pressure stay 119 is a support member or a reinforcing member in this embodiment. The pressure roller 110 is a second rotating body in the fixing device 100 in this embodiment. In addition, the pressure roller 110 is a pressure member in this embodiment.

[0021] The fixing film 112 is a first rotating body in the fixing device 100 of this embodiment. The fixing film 112 is a flexible cylindrical (endless) film member (belt member). The fixing film 112 of this embodiment has an outer diameter of 18 mm in an undeformed cylindrical state, and has a multi-layer structure in the thickness direction. The layer structure of the fixing film 112 includes at least a base layer for maintaining the strength of the film, and a release layer for reducing adhesion of dirt to the surface.

[0022] The material of the base layer is preferably one that has heat resistance to withstand the heat of the heater 113 and has sufficient strength to slide with the heater 113. As the material of the base layer, metals such as stainless steel and nickel, and heat-resistant resins such as polyimide can be preferably used. In this embodiment, polyimide resin with carbon-based filler added thereto to improve thermal conductivity and strength is used as the material of the base layer of the fixing film 112. The thinner the thickness of the base layer, the easier it is to transmit the heat of the heater 113 to the surface of the recording material P, but the strength decreases, so that the thickness is preferably about 15 μm to 100 μm, and is set to 60 μm in this embodiment.

[0023] The material of the release layer of the fixing film 112 can be suitably made of fluororesins such as perfluoroalkoxy resin (PFA), polytetrafluoroethylene resin (PTFE), and tetrafluoroethylene-hexafluoropropylene resin (FEP). In this embodiment, PFA, which has excellent releasability and heat resistance among fluororesins, is used. The release layer may be formed by covering the base layer with a tube, or by coating the surface of the base layer with paint. In this embodiment, the release layer is formed by a coating method that is excellent in thin-wall molding. The thinner the release layer is, the easier it is to transfer heat from the heater 113 to the surface of the fixing film 112, but if it is too thin, it becomes difficult to ensure durability, so that the thickness is preferably about 5 μm to 30 μm, and is set to 10 μm in this embodiment. In addition, although not used in this embodiment, an elastic layer may be provided between the base layer and the release layer. In that case, silicone rubber, fluororubber, or the like is used as the material of the elastic layer.

[0024] The heater holder 130 is provided on the inner periphery side of the fixing film 112. The heater holder 130 has a substantially semicircular arc gutter shape in cross section (cross section in a plane perpendicular to the longitudinal direction B). That is, the surface of the heater holder 130 facing the fixing nip Nf is curved convexly toward the pressure roller 110 side in the vertical direction C, and a heater holding portion (fitting portion) for holding the heater 113 is provided at the substantially center of the curved surface in the recording material conveying direction A. The heater holding portion opens toward the pressure roller 110 side in the vertical direction C and has a groove shape elongated in the longitudinal direction B. The heater holder 130 is formed of a liquid crystal polymer resin having high heat resistance in order to satisfy heat resistance and rigidity. In this embodiment, Sumika Super E5204L (registered trademark) manufactured by Sumitomo Chemical Co., Ltd. is used as the liquid crystal polymer resin.

[0025] The heater holder 130 has a heater seating surface S1 that supports the heater 113, an upstream protruding portion 131 and a downstream protruding portion 132 adjacent to the heater seating surface S1, and a stay contact surface S3 provided on the opposite side to the heater seating surface S1 in the vertical direction C1. The heater seating surface S1 is a first surface of the heater holder 130 provided on the pressure roller 110 side in the vertical direction C that is perpendicular to both the recording material conveying direction A and the longitudinal direction B. The heater seating surface S1 supports the surface of the heater 113 opposite to the pressure roller 110 in the vertical direction C (i.e., the surface opposite to the sliding surface S2).

[0026] The upstream protrusion 131 is provided on the upstream side of the heater seating surface S1 in the recording material conveying direction A, and protrudes toward the pressure roller 110 in the vertical direction C compared to the heater seating surface S1. The downstream protrusion 132 is provided on the downstream side of the heater seating surface S1 in the recording material conveying direction A, and protrudes toward the pressure roller 110 in the vertical direction C compared to the heater seating surface S1. The heater seating surface S1 is the bottom of a groove shape (heater holding portion) formed between the upstream protrusion 131 and the downstream protrusion 132. In addition, the upstream protrusion 131 and the downstream protrusion 132 have sliding surfaces that slide against the inner surface of the fixing film 112 upstream and downstream of the sliding surface S2 of the heater 113 in the recording material conveying direction A, respectively.

[0027] Furthermore, the heater holder 130 has an upstream guide 126 that guides the fixing film 112 on the upstream side of the fixing nip Nf in the recording material conveying direction A, and a downstream guide 127 that guides the fixing film 112 on the downstream side of the fixing nip Nf. In other words, the heater holder 130 has a role of holding the heater 113 and guiding the rotation of the fixing film 112.

[0028] Both the upstream guide 126 and the downstream guide 127 extend in the direction perpendicular to the stay contact surface S3 of the heater holder 130, on the opposite side to the pressure roller 110. In detail, as shown in FIG. 6, the upstream guide 126 and the downstream guide 127 include a wall portion 124 rising in the direction perpendicular to the stay contact surface S3 in the recording material conveying direction A, and a guide rib 129 provided at a plurality of positions on the wall portion 124 in the longitudinal direction B. The end surface of the guide rib 129 is curved along the natural shape (FIG. 2(a)) formed when the fixing film 112 is pressed in the fixing nip Nf, as described above. The upstream guide 126 and the downstream guide 127 guide the rotation trajectory of the fixing film 112 by the end surface of the guide rib 129. The upstream guide 126 is a first guide portion in this embodiment that guides the inner surface of the fixing film 112 toward the fixing nip Nf. The downstream guide 127 is a second guide portion in this embodiment that guides the inner surface of the fixing film 112 that has passed through the fixing nip Nf.

[0029] Instead of the configuration in which the fixing film 112 is guided by the guide rib 129 protruding from the wall portion 124, the wall portion 124 itself may have a cross-sectional shape similar to that of the guide rib 129 of this embodiment, and the fixing film 112 may be guided by the outer surface of the wall portion 124. In this case, the guide rib 129 may be continuous with the outer surface of the wall portion 124 and guide the fixing film 112 upstream or downstream in the rotation direction of the fixing film 112 from the outer surface of the wall portion 124, or the guide rib 129 may be omitted.

[0030] The heater 113 and the heater holder 130 are disposed in the internal space of the fixing film 112, and function as a nip forming unit that forms the fixing nip Nf by being pressed against the pressure roller 110 with the fixing film 112 sandwiched therebetween. Note that, in this embodiment, a configuration in which the heater 113 directly slides against the inner surface of the fixing film 112 is described, but a configuration in which a sliding member is interposed between the heater 113 and the fixing film 112 may also be used. As the sliding member, a member having high thermal conductivity and high slidability against the inner surface of the fixing film 112 is used, and for example, a sheet-like member made of alloy iron or aluminum may be used. In other words, the nip forming unit may be configured such that the heater 113 indirectly heats the fixing film 112 via the sliding member.

[0031] The pressure stay 119 is disposed along the longitudinal direction B of the heater holder 130. The pressure stay 119 is made of a highly rigid metal plate such as stainless steel that has been bent to apply uniform pressure to the heater holder 130 in the longitudinal direction. When viewed in the longitudinal direction B, the pressure stay 119 is formed in a U-shape (an angular C-shape) that is open on the side of the pressure roller 110 in the vertical direction C. attitude That is, the pressure stay 119 has a first portion 91 extending in the recording material transport direction A, and a second portion 92 and a third portion 93 extending from the upstream end and downstream end of the first portion 91 in the recording material transport direction A toward the heater holder 130 in the vertical direction C, respectively.

[0032] One end 119a of the pressure stay 119 is in contact with the stay contact surface S3 of the heater holder 130 upstream of the heater seating surface S1 in the recording material transport direction A. The other end 119b of the pressure stay 119 is in contact with the stay contact surface S3 of the heater holder 130 downstream of the heater seating surface S1 in the recording material transport direction A. In other words, the pressure stay 119 is in contact with the stay contact surface S3 (second surface) of the heater holder 130 at the ends 119a and 119b which are the tips of the second portion 92 and the third portion 93.

[0033] The pressure stay 119 supports the heater holder 130 against the nip pressure in the fixing nip Nf by pressing the stay contact surface S3 at the end portion 119a toward the pressure roller 110 in the vertical direction C. That is, the pressure stay 119 functions as a support member that supports the nip forming unit including the heater 113 and the heater holder 130.

[0034] The pressure roller 110 in this embodiment has an outer diameter of 20 mm, and an elastic layer 116 having a thickness of 3.0 mm is formed on the outer circumference of an iron core metal 117 having a diameter of 14 mm. The material of the elastic layer 116 is solid rubber or foamed rubber. Foamed rubber has a low heat capacity and low thermal conductivity, and the heat on the surface of the pressure roller 110 is not easily absorbed into the inside, so the surface temperature is easily increased, and there is an advantage that the start-up time of the fixing device 100 can be shortened. In this embodiment, foamed rubber obtained by foaming silicone rubber is used as the elastic layer 116. On the elastic layer 116, a release layer 118 made of perfluoroalkoxy resin (PFA) is formed as a release layer. The release layer 118 may be a tube covering or a surface of the elastic layer 116 coated with paint, like the release layer of the fixing film 112. In this embodiment, the release layer 118 is formed by covering the outer circumference of the elastic layer 116 with a tube having excellent durability. As the material of the release layer 118, in addition to PFA, fluororesins such as PTFE and FEP, fluororubber and silicone rubber with good releasability, etc. may be used. The lower the surface hardness of the pressure roller 110, the lighter the pressure required to obtain the width of the fixing nip Nf, but the surface hardness is also determined in consideration of durability. In this embodiment, a roller with Asker-C hardness (load of 4.9 N) of 50° is used. Note that instead of the pressure roller 110, a belt unit including a belt member stretched over multiple rollers may be used as the pressure member.

[0035] The heater 113 in this embodiment is a ceramic substrate on which a resistance heating element is provided. Specifically, an alumina substrate having a width of 6 mm in the recording material conveying direction A and a thickness of 1 mm in the vertical direction C is used as the substrate for the heater 113. The heater 113 was created by applying an Ag / Pd (silver palladium) resistance heating element to a thickness of several μm by screen printing on the surface of this substrate, and then forming a glass layer to a thickness of 60 μm on top of that to protect the heating element and improve sliding properties.

[0036] The fixing device 100 is configured to be able to adjust the temperature of the heater 113 by appropriately controlling the current flowing through the resistance heating element in response to a signal from a temperature detection element (thermal element) (described later) that detects the temperature of the substrate of the heater 113 or the fixing film 112. The heater 113 is fitted into and fixedly supported in a groove portion provided in the heater holder 130. In this embodiment, the center of the heater 113 in the recording material transport direction A is located 0.4 mm upstream of the center (rotation axis) of the pressure roller 110.

[0037] As shown in FIG. 2B, the pressure stay 119 has an extension 119e that penetrates the side plates 134 on both sides in the longitudinal direction B constituting the frame 133 of the fixing device 100 and extends outside the side plates 134. Fixing flanges 120 are fitted to the extensions 119e on both sides of the pressure stay 119. The fixing flanges 120 are supported by the side plates 134, so that the film unit 101 is mounted between the side plates 134 on both sides with the heater 113 facing the pressure roller 110 in the vertical direction C. Each fixing flange 120 is provided with a vertical groove extending in the vertical direction C, and the vertical groove is engaged with the edge of a vertical guide slit provided in the side plate 134. As a result, each fixing flange 120 is supported by the side plate 134 so as to be movable in the vertical direction C. In this embodiment, a liquid crystal polymer resin is used as the material of the fixing flanges 120.

[0038] The core metal 117 of the pressure roller 110 has a shaft portion 117a penetrating side plates 134 on both sides, and each shaft portion 117a is held by a bearing member 135 engaged with the side plate 134. In this way, the pressure roller 110 is rotatably supported by the frame 133.

[0039] Then, the pressure spring 122 is compressed between the pressure portion 120b of the fixing flange 120 and the spring support portion 121 fixed to the frame 133. As a result, the urging force of the pressure spring 122 is transmitted to the heater 113 via the fixing flanges 120 on both sides, the pressure stays 119, and the heater holder 130, and the heater 113 is pressed against the pressure roller 110 with a predetermined pressing force, sandwiching the fixing film 112.

[0040] In this embodiment, the spring constant and compression amount of the pressure spring 122 are set so that the pressure force with which the fixing film 112 and the pressure roller 110 press against each other in the vertical direction C at the fixing nip Nf is 15 kgf. At the fixing nip Nf, the fixing film 112 is sandwiched between the heater 113 and the pressure roller 110 and bends following the sliding surface S2, which is a flat surface on the front side of the heater 113, so that the inner surface of the fixing film 112 is in close contact (surface contact) with the sliding surface S2. The film regulating portion 120a of the fixing flange 120 has a shape that follows the natural shape (see FIG. 2(a)) that is formed when the fixing film 112 is pressed at the fixing nip Nf.

[0041] When a driving force transmitted from a driving source (not shown) is input to a driving gear 117g (FIG. 2B) provided on a shaft portion 117a of the pressure roller 110, the pressure roller 110 is rotated at a predetermined speed in the direction of arrow R2 in FIG. 2A. As the pressure roller 110 is rotated, a rotational force acts on the fixing film 112 due to a frictional force between the pressure roller 110 and the fixing film 112 in the fixing nip Nf. As a result, the fixing film 112 rotates in the direction of arrow R3 in the figure around the heater 113 and the heater holder 130 following the rotation of the pressure roller 110 while sliding its inner surface against the sliding surface S2 of the heater 113. The rotational speed of the pressure roller 110 is set so that the surface movement speed of the pressure roller 110 and the fixing film 112 in the fixing nip Nf is 200 mm / sec.

[0042] When fixing an image, the pressure roller 110 is driven while energizing the heater 113, so that the recording material is sandwiched and conveyed between the pressure roller 110 and the fixing film 112 at the fixing nip Nf. At the same time, the image on the recording material is heated by the fixing film 112 heated by the heater 113, so that the image is thermally fixed.

[0043] A heat-resistant lubricant is applied to the inner surface of the fixing film 112, thereby ensuring the sliding properties between the heater 113 and the heater holder 130 and the inner surface of the fixing film 112. In this embodiment, a fluorine-based grease is used as the lubricant. Specifically, perfluoropolyether (PFPE) oil is used as the base oil, and Minoru The agent used was grease mixed with polytetrafluoroethylene (PTFE) powder.

[0044] (Heater holder) 3 is a schematic diagram for explaining the crown shape of the heater holder 130 in the longitudinal direction B. As shown in FIG. 3, the heater holder 130 has a gently curved shape (i.e., a crown shape) such that the central portion in the longitudinal direction B of the heater seating surface S1 supporting the heater 113 protrudes toward the pressure roller 110 in the vertical direction C compared to both ends. The heater 113 is fixed to the heater holder 130 at both ends in the longitudinal direction B by a heater power supply portion 136 and a heater clip 137. Therefore, the heater 113 is attached in a curved state following the crown shape of the heater seating surface S1.

[0045] A specific example of the crown shape of the heater seating surface S1 is a gentle quadratic curve shape as viewed in the recording material conveying direction A in an area CR with a longitudinal width of 225 mm, which corresponds to the range in the longitudinal direction B where the heater 113 faces the pressure roller 110. The amount of protrusion of the center of the heater seating surface S1 in the vertical direction C from both ends is, for example, 0.4 mm.

[0046] By providing such a crown shape, it is possible to form a fixing nip Nf of uniform width over almost the entire area in the longitudinal direction B. In other words, when the film unit 101 is pressed against the pressure roller 110 by the urging force of the pressure spring 122, the pressure stay 119 and the core metal 117 of the pressure roller 110 are slightly bent. If the heater seat surface S1 does not have a crown shape, the heater 113 is strongly pressed against the pressure roller 110 at both ends in the longitudinal direction B, and the nip width of the fixing nip Nf becomes wide, while the nip width of the fixing nip Nf becomes narrow at the center in the longitudinal direction B. In contrast, by providing a crown shape as in this embodiment, it is possible to reduce the difference in the nip width of the fixing nip Nf between the center and both ends in the longitudinal direction B. The width of the fixing nip Nf in the recording material conveying direction A in this embodiment is about 6.2 mm over the entire area CR in the longitudinal direction B.

[0047] Next, the opening O of the heater holder 130 will be described. Fig. 4(a) is a perspective view of the heater holder 130 seen from the heater seating surface S1 side. Fig. 4(b) is a cross-sectional view (cross-section on a plane perpendicular to the longitudinal direction B) of the fixing device 100 at a portion where the temperature detection element T is arranged (broken line 4B-4B in Fig. 4(a)).

[0048] As shown in FIG. 4(a), an opening O is provided in the heater seating surface S1 of the heater holder 130 for fitting a temperature detection element T such as a temperature fuse, a thermoswitch, or a thermistor. As shown in FIG. 4(b), the opening O is a hole that penetrates the heater holder 130 in the vertical direction C from the heater seating surface S1 to the stay contact surface S3 on the opposite side. The opening O of the heater holder 130 allows the temperature detection element T to be arranged in contact with the heater 113. The temperature detection element T emits a signal according to the temperature of the heater 113. Note that the temperature detection element T may be arranged close to the heater 113 with a predetermined gap therebetween, without being in contact with the heater 113.

[0049] By using a thermal fuse or a thermoswitch as the temperature detection element T, the control unit 51 of the image forming apparatus 50 can control the power supply circuit 52 of the heater 113 based on a signal from the temperature detection element T to cut off the power supply to the heater 113. The power supply circuit 52 has a cutoff circuit such as a relay that can cut off the power supply to the heater 113 based on a command from the control unit 51. In this case, the control unit 51 and the cutoff circuit function as a cutoff means (safety device) that detects an abnormal temperature rise of the heater 113 and cuts off the power supply to the heater 113. In addition, by using a thermistor as the temperature detection element T, the control unit 51 can control the amount of power supplied from the power supply circuit 52 to the heater 113 based on a signal from the temperature detection element T. In this case, the control unit 51 functions as a temperature control means (temperature adjustment device) that controls the temperature of the heater 113 to match a predetermined target temperature.

[0050] Here, the peripheral portion of the opening O of the heater holder 130 has lower rigidity than other portions of the heater holder 130. Therefore, in this embodiment, as described later, a reinforcing rib 123 is provided in the vicinity of the opening O on the stay contact surface S3 on the rear side of the heater seating surface S1.

[0051] Next, a description will be given of the rotation orbit of the fixing film 112 regulated by the heater holder 130. Fig. 5 is a cross-sectional view of the fixing nip Nf and its vicinity at the center in the longitudinal direction B.

[0052] As described above, the heater holder 130 has an upstream protruding portion 131 that protrudes toward the pressure roller 110 side from the heater seat surface S1, upstream of the heater 113 in the recording material conveying direction A. It is desirable that the protruding height H of the upstream protruding portion 131 with respect to the sliding surface S2 of the heater 113 is a certain height in order to regulate the trajectory of the fixing film 112 so that the fixing film 112 does not contact the edge portion of the heater 113 (the edge portion on the upstream side in the recording material conveying direction A). However, if the protruding height H is made too high, the fixing film 112 is pressed by the upstream protruding portion 131, and the contact width (inner surface nip width Nn) between the inner surface of the fixing film 112 and the heater 113 is reduced. In this case, the heat transfer from the heater 113 to the fixing film 112 is impaired, which is a cause of poor fixing.

[0053] The protruding height H of the upstream protruding portion 131 relative to the sliding surface S2 of the heater 113 is preferably about 0.1 to 0.7 mm, for example, and is set to 0.2 mm in this embodiment. The inner surface nip width Nn is preferably 4 mm or more, and is set to 4.2 mm in this embodiment.

[0054] (Heater holder reinforcing rib) Next, the shape of the reinforcing rib 123 provided on the heater holder 130 according to this embodiment and its positional relationship with the pressure stay 119 will be described.

[0055] 6 is a perspective view of the heater holder 130 seen from the opposite side to the heater seating surface S1, and particularly shows an enlarged view of the vicinity of the opening O where the temperature detection element T is disposed. As shown in Fig. 6, reinforcing ribs 123 extending in the recording material transport direction A are formed in two places so as to sandwich the opening O of the heater holder 130 from both sides in the longitudinal direction B. The reinforcing ribs 123 are rib portions (protruding portions) that are protruded in the vertical direction C from the stay contact surface S3 (second surface) of the heater holder 130 and extend in the recording material transport direction A (the short side direction of the heater 113).

[0056] 7 is a cross-sectional view of the fixing device 100 in a portion where the reinforcing rib 123 is arranged in the longitudinal direction B. As shown in FIGS. 6 and 7, the reinforcing rib 123 in this embodiment extends in the recording material conveying direction A so as to connect the upstream guide 126 and the downstream guide 127 of the heater holder 130. The upstream guide 126 and the downstream guide 127 are connected by the reinforcing rib 123, thereby improving the bending rigidity of the heater holder 130 against the force applied from the pressure stay 119 and the pressure roller 110. Note that the reinforcing rib 123 may be connected to either the wall portion 124 or the guide rib 129 of the upstream guide 126 and the downstream guide 127.

[0057] The reinforcing rib 123 protrudes from the stay contact surface S3 of the heater holder 130 in the vertical direction C toward the opposite side to the pressure roller 110. Therefore, a cutout 119c is provided at the ends 119a, 119b of the pressure stay 119 facing the heater holder 130 to avoid the reinforcing rib 123 (FIG. 7). When viewed in the recording material conveying direction A, the cutout 119c is a concave shape in which a part of the ends 119a, 119b of the heater holder 130 extending in the longitudinal direction B is recessed in the vertical direction C toward the opposite side to the pressure roller 110. In other words, the second portion 9 of the pressure stay 119, which is a support member, 2 The third portion 93 is provided with a notch 119c having a concave shape that is recessed in the vertical direction C in a direction away from the stay contact surface S3 (second surface) of the heater holder 130 and extends in the recording material conveying direction A. A reinforcing rib 123 serving as a rib portion extends in the recording material conveying direction A through the inside of the notch 119c.

[0058] In this embodiment, the height Hr of the reinforcing rib 123 in the vertical direction C is 1.5 mm, and the width Wr of the reinforcing rib 123 in the longitudinal direction B is 2.0 mm. Also, the height of the cutout portion 119c of the pressure stay 119 in the recording material transport direction A is 2.0 mm, and the width of the cutout portion 119c in the longitudinal direction B is 2.5 mm. This prevents the reinforcing rib 123 from contacting the pressure stay 119, and enables the pressure stay 119 to press the heater holder 130 with a substantially uniform force in the longitudinal direction B even with the reinforcing rib 123 provided.

[0059] (Effects of this embodiment) The suppression of creep deformation of the heater holder 130 by the configuration of this embodiment will be described with reference to FIGS.

[0060] Fig. 8 is a schematic diagram for explaining the stress acting on the heater holder 130 in the pressurized state of the fixing nip Nf. As shown in Fig. 8, the heater holder 130 receives a force F1 from the ends 119a and 119b of the pressure stay 119 toward the pressure roller 110 in the vertical direction C at the stay contact surface S3. The heater holder 130 also receives a force F2 in the vertical direction C on the opposite side to the pressure roller 110 as a reaction force received from the pressure roller 110 supported by the bearing member 135 via the fixing film 112 and the heater 113.

[0061] As a result, a bending moment acts on the heater holder 130 such that the heater seating surface S1 is displaced in the vertical direction C toward the opposite side to the pressure roller 110 between the contact portions (first position P1, second position P2) with the pressure stay 119. In other words, a bending moment is generated that tries to bend the heater holder 130 so that the upstream protrusion 131 and the downstream protrusion 132 are displaced in the vertical direction C toward the pressure roller 110 with respect to the heater 113.

[0062] If the heater holder 130 is deformed by such a bending moment, the fixing performance of the fixing device 100 may be degraded.

[0063] Next, a reference example will be used to explain a case where the heater holder 130 is deformed by a bending moment. Fig. 9 is a cross-sectional view of the fixing device 100 in the vicinity of the opening of the heater holder 130 in the reference example, and the heater holder 130 does not have the reinforcing rib 123 as in this embodiment.

[0064] When a paper feed test was conducted in which an image was formed on LTR size paper using an image forming apparatus 50 equipped with the fixing device 100 of this reference example, no damage to the heater holder 130 or wrinkles in the recording material occurred. If the mechanical strength or dimensional accuracy of the heater holder 130 were insufficient, the heater holder 130 could be damaged, or the running of the fixing film 112 could become unstable, causing the fixing film 112 to shift sideways or wrinkles in the recording material. In contrast, it is considered that the mechanical strength and dimensional accuracy of the heater holder 130 were sufficiently ensured in the fixing device 100 of the reference example.

[0065] On the other hand, in this reference example, when a durability test was performed in which images were repeatedly formed on a large number of sheets of paper, poor fixing occurred and gradually worsened as the cumulative number of sheets passed increased. This is believed to be due to a decrease in the inner nip width Nn, which is the contact width between the inner surface of the fixing film 112 and the heater 113, caused by the creep deformation of the heater holder 130 due to the bending moment described above. In other words, it is believed that the upstream protrusion 131 and the downstream protrusion 132 were displaced in the vertical direction C toward the pressure roller 110 relative to the heater 113, causing the fixing film 112 to become separated from a part of the heater 113. When the inner nip width Nn decreases, the surface temperature of the fixing film 112 decreases, and when it falls below the lower limit of the temperature range suitable for fixing an image, it becomes apparent as poor fixing.

[0066] In the durability test, the fixing failure occurred at a position on the sheet corresponding to the vicinity of the opening O of the heater holder 130 in the longitudinal direction B. This is considered to be because the creep deformation of the heater holder 130 occurred mainly in the vicinity of the opening O, which has a relatively low rigidity, due to the bending moment described above.

[0067] Next, the present embodiment will be described with reference to Fig. 7. As described above, the heater holder 130 of this embodiment is formed with the reinforcing rib 123 that is provided in a protruding manner on the stay contact surface S3 and extends in the recording material transport direction A. The reinforcing rib 123 improves the bending rigidity of the heater holder 130 against the bending moment (Fig. 8) that the heater holder 130 receives in the pressurized state of the fixing nip Nf, making creep deformation of the heater holder 130 less likely to occur.

[0068] In particular, in this embodiment, the reinforcing rib 123 is disposed near the opening O of the heater holder 130 in the longitudinal direction B. This makes it possible to improve the bending rigidity near the opening O, which has lower rigidity compared to a portion without the opening O, and effectively suppress creep deformation of the heater holder 130.

[0069] The reinforcing rib 123 is preferably disposed over at least the range where the heater seating surface S1 (first surface) is provided in relation to the recording material conveying direction A. This allows the reinforcing rib 123 to improve the bending rigidity of the portion of the heater holder 130 where the thickness in the vertical direction C is thinned due to the space for receiving the heater 113, thereby suppressing creep deformation.

[0070] 8 in relation to the recording material conveying direction A. The first position P1 is a position where the pressure stay 119 abuts against the stay contact surface S3 of the heater holder 130 on the upstream side of the heater 113, and the second position P2 is a position where the pressure stay 119 abuts against the stay contact surface S3 of the heater holder 130 on the downstream side of the heater 113. This improves the bending rigidity by the reinforcing rib 123 in a range where a bending moment acts on the heater holder 130 due to forces F1 and F2 that the heater holder 130 receives from the pressure stay 119 and the pressure roller 110, and makes it possible to more effectively suppress creep deformation.

[0071] More preferably, as in this embodiment, the reinforcing rib 123 is configured to be continuous in the recording material conveying direction A from the upstream guide 126 (first guide portion) to the downstream guide 127 (second guide portion) of the heater holder 130. This further improves the bending rigidity of the heater holder 130 and further suppresses creep deformation.

[0072] When a paper feed test was conducted using LTR size paper using an image forming apparatus 50 equipped with the fixing device 100 of this embodiment, no damage occurred to the heater holder 130 and no wrinkling occurred in the recording material. In addition, even when a durability test was conducted, a state in which a uniform fixed image was obtained over the entire area in the longitudinal direction B without occurrence of abnormal images such as poor fixing was maintained for a long period of time. This is believed to be because creep deformation of the heater holder 130 was suppressed by the reinforcing rib 123 disposed near the opening O of the heater holder 130.

[0073] As an alternative means for improving the bending rigidity of the heater holder 130 and preventing creep deformation, it is possible to increase the thickness of the heater holder 130 at the portion where the heater seating surface S1 and the stay contact surface S3 are provided. However, this configuration increases the heat capacity of the heater holder 130, and the warm-up time of the fixing device 100 becomes longer. In contrast, by using the reinforcing rib 123 as in this embodiment, it is possible to improve the bending rigidity of the heater holder 130 while suppressing an increase in the heat capacity of the heater holder 130. In other words, the configuration of this embodiment makes it possible to suppress creep deformation of the heater holder 130 while suppressing the effect on the warm-up time of the fixing device 100. EXAMPLES

[0074] Example 2 of the present disclosure will be described below. After performing a paper feed evaluation using A4 size paper using an image forming apparatus 50 equipped with the fixing device 100 of Example 1, when checking an image on an LTR size paper, very slight fixing failures were observed on both the left and right edges of the image in some cases. This example makes it possible to further suppress the occurrence of such fixing failures.

[0075] In this embodiment, a reinforcing rib 123 is further added to the heater holder 130 used in embodiment 1. Other configurations are substantially the same as those in embodiment 1. Hereinafter, elements with the same reference numerals as in embodiment 1 have substantially the same configurations and functions as those described in embodiment 1, and differences from embodiment 1 will be mainly described.

[0076] (Heater holder reinforcing rib) The reinforcing rib 123 of the heater holder 130 according to this embodiment will be described with reference to Fig. 10. As shown in Fig. 10, the reinforcing rib 123 added in this embodiment is disposed between the end position of the A4 size paper and the end position of the resistance heating element on the heater 113 in the longitudinal direction B. In other words, the rib portion in this embodiment is disposed inside the area where the heater 113 generates heat, in the longitudinal direction B, and outside the area where recording materials pass that are narrower in width in the longitudinal direction B than the recording material with the widest width in the longitudinal direction B among the recording materials on which the fixing device 100 can fix an image.

[0077] In this embodiment, reinforcing ribs 123 are added at positions 107.5 mm away on both sides of a reference position (hereinafter, the conveyance center of the recording material) for the center position of the recording material passing through the fixing nip Nf in the longitudinal direction B. This is because, using the conveyance center of the recording material in the longitudinal direction B as a reference, the distance to the edge position of A4 size paper is 105 mm, and the distance to the edge position of the resistance heating element on the heater 113 is 110 mm.

[0078] The reinforcing rib 123 added in this embodiment is formed so as to connect the upstream guide 126 and the downstream guide 127 of the heater holder 130, like the reinforcing rib 123 described in the first embodiment. In this embodiment, the height Hr of the reinforcing rib 123 in the vertical direction C is 1.5 mm, and the width Wr is 2.0 mm.

[0079] In addition, in accordance with the addition of the reinforcing rib 123, a cutout portion that receives the reinforcing rib 123 is added to the pressure stay 119. The height of the cutout portion formed in the pressure stay 119 in the recording material conveying direction A is 2.0 mm, and the width in the longitudinal direction B is 2.5 mm, so that the reinforcing rib 123 does not come into contact with the pressure stay 119.

[0080] (Temperature rise without paper passing) The fixing device 100 and image forming device 50 of this embodiment can form images on a maximum LTR size paper (width 216 mm in the longitudinal direction B) in the same manner as in the first embodiment. In other words, LTR size paper is the maximum passable paper in this embodiment. Accordingly, the width in the longitudinal direction B of the resistance heating element on the heater 113 is set to include an effective image area where an image can be formed on the maximum passable paper.

[0081] Here, when performing image formation on a recording material (small size paper) whose width in the longitudinal direction B is smaller than that of the maximum paper that can be passed, there is an area in the fixing nip Nf where the recording material does not pass and is heated by the resistance heating element (hereinafter, non-paper passing area). Therefore, when performing image formation continuously on small size paper (e.g., A4 size paper), the surface temperature of the fixing film 112 and the pressure roller 110 in the non-paper passing area may be higher than the paper passing area where the small size paper passes. This is because in the non-paper passing area, heat is not absorbed by the recording material in the fixing nip Nf, so the heat generated by the resistance heating element gradually accumulates. This phenomenon is called "non-paper passing area temperature rise."

[0082] When image formation is performed continuously on small size paper due to the temperature rise in the non-paper passing area, the heater holder 130 has a thermal peak in the non-paper passing area (outside the paper passing area and within the heat generating area of ​​the heater 113). In other words, if the temperature of the non-paper passing area of ​​the heater holder 130 continues to be higher than that of the paper passing area due to the temperature rise in the non-paper passing area, creep deformation of the heater holder 130 may occur in the non-paper passing area.

[0083] (Effects of this embodiment) The following describes how this embodiment suppresses creep deformation in the non-paper passing area of ​​the heater holder 130. In this embodiment, reinforcing ribs 123 are arranged in the non-paper passing area of ​​the heater holder 130, improving the bending rigidity of the heater holder 130 in the non-paper passing area. Therefore, even if forces F1 and F2 and heat due to the non-paper passing area temperature rise act simultaneously on the heater holder 130 in the non-paper passing area as shown in FIG. 8, creep deformation of the heater holder 130 is unlikely to occur.

[0084] When a paper feed test was carried out by forming an image on A4 size paper using the image forming apparatus 50 equipped with the fixing device 100 of this embodiment, there was no damage to the heater holder 130 or wrinkles in the recording material. In addition, even when a durability test was carried out, there was no occurrence of abnormal images such as poor fixing, and the state in which a uniform fixed image was obtained over the entire area in the longitudinal direction B was maintained for a long period of time.

[0085] Furthermore, even when a paper feed test using LTR size paper was performed after a durability test using A4 size paper, no fixing failure occurred. This is believed to be because the reinforcing rib 123 added in this embodiment was able to suppress creep deformation of the heater holder 130 in the non-paper feed area.

[0086] In this embodiment, a configuration has been exemplified in which reinforcing rib 123 is arranged in the non-paper passing area in addition to the reinforcing rib 123 described in Example 1, but it is also possible to arrange only the reinforcing rib 123 in the non-paper passing area described in this embodiment.

[0087] (Modification) In the first and second embodiments, the reinforcing rib 123 is provided between the upstream guide 126 and the downstream guide 127 in the recording material conveying direction A on the flat stay contact surface S3. This is not limiting, but the reinforcing rib 123 can be provided even when the surface of the heater holder 130 opposite to the heater seat surface S1 (first surface) is uneven when viewed in the longitudinal direction B. For example, as shown in FIG. 11(a), when the heater holder 130 has two ribs 128 extending in the longitudinal direction B between the upstream guide 126 or the downstream guide 127, the reinforcing rib 123 connecting the ribs 128 may be provided. The rib 128, together with the upstream guide 126 or the downstream guide 127, forms a recess for receiving the ends 119a, 119b of the pressure stay 119. As a further modification of FIG. 11(a), the reinforcing rib 123 may be configured to intersect with the rib 128, extend to the outside of the rib 128, and connect to the upstream guide 126 and the downstream guide 127.

[0088] 11B, in a configuration in which a step portion 138 is provided on the inner side of the upstream guide 126 and the downstream guide 127 in the recording material transport direction A, a reinforcing rib 123 may be formed so as to connect the step portion 138. In this case, since the pressure stay 119 abuts against the heater holder 130 at the step portion 138, the reinforcing rib 123 is located inside the abutment position of the pressure stay 119 and the heater holder 130, and no notch is required in the pressure stay 119.

[0089] As another modification, as shown in FIG. 11(c), a film guide 139 for guiding the rotation of the fixing film 112 may be provided separately from the heater holder .

[0090] 11(a-c) are examples of rib portions that are not continuously provided from the upstream guide 126 (first guide portion) to the downstream guide 127 (second guide portion) of the heater holder 130. Even in these modified examples, the provision of the reinforcing rib 123 improves the bending rigidity of the heater holder 130 and suppresses creep deformation, so that stable fixing performance can be obtained for a long period of time.

[0091] Furthermore, in the first and second embodiments, the reinforcing rib 123 is disposed in the heater holder 130 near the opening O in the longitudinal direction B or in a non-paper passing region at an end of the longitudinal direction B. The arrangement of the reinforcing rib 123 is not limited to this. For example, a plurality of reinforcing ribs 123 may be disposed at predetermined intervals in the longitudinal direction B. Also, it is sufficient to dispose at least one reinforcing rib 123. In any of the modified examples, the reinforcing rib 123 improves the bending rigidity of the heater holder 130, and creep deformation of the heater holder 130 can be suppressed.

[0092] (Other embodiments) In the above-mentioned first and second embodiments, a ceramic heater having a resistance heating element formed on a ceramic substrate is used as the heating means (heater) of the fixing device, and the fixing film 112 is heated by non-radiative heat of the ceramic heater. However, the present invention is not limited to this, and a halogen lamp may be used as the heater. That is, the nip forming unit may be a halogen lamp disposed in the internal space of the first rotating body, and a sliding member (nip forming portion) that contacts the inner surface of the first rotating body and heats the first rotating body by receiving radiant heat from the halogen lamp. Even in this case, creep deformation can be suppressed by providing a rib portion (reinforcing rib) on the holder member that holds the nip forming unit.

[0093] In addition, in the above-mentioned first and second embodiments, a film is used as the first rotating body and a roller is used as the second rotating body, but the first and second rotating bodies are not limited to this combination. For example, a roller member may be used as the first rotating body. [Explanation of symbols]

[0094] 100... fixing device / 110... second rotating body (pressure roller) / 112... first rotating body, film (fixing film) / 113... heater / 119... support member (pressure stay) / 123... rib portion (reinforcement rib) / 130... holder member (heater holder) / S1... first surface (heater seat surface) / S3... second surface (stay contact surface)

Claims

1. A first rotating body; a nip forming unit including an elongated heater and a holder member for holding the heater, the nip forming unit being disposed in an internal space of the first rotating body; A detection element that generates a signal in response to the temperature of the heater; a second rotor that is in pressure contact with the nip forming unit across the first rotor and forms a nip between the second rotor and the nip forming unit; a support member disposed in the internal space of the first rotor and supporting the nip forming unit; a fixing device for fixing an image on a recording material by heating the image on the recording material with the first rotating body heated by the heater while the recording material is nipped and conveyed between the first rotating body and the second rotating body at the nip portion, The holder member includes: a first surface that is provided on the second rotating body side in a thickness direction perpendicular to both the longitudinal direction and the lateral direction of the heater in the nip portion and supports the heater; a second surface provided on an opposite side of the first surface in the thickness direction and facing the support member; a rib portion that is protruding from the second surface and extends in the short-side direction at least over a range in which the first surface is provided; having The holder member has a hole formed therein, the hole passing through the holder member from the first surface to the second surface, the sensing element is disposed in the hole; The rib portion is provided on both sides of the hole in the longitudinal direction. A fixing device comprising:

2. the support member has a first contact portion that contacts the holder member on one side of the heater in the short side direction, and a second contact portion that contacts the holder member on the other side of the heater in the short side direction, and supports the holder member against a pressing force received by the holder member from the second rotating body via the first rotating body and the heater.

2. The fixing device according to claim 1,

3. From one end of the rib portion to the other end in the short direction, the width of the rib portion in the long direction is constant, and the height of the rib portion in the thickness direction is constant.

3. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing roller.

4. a first guide portion provided on one side of the nip portion in the short side direction, extending to an opposite side of the second rotating body in the thickness direction with respect to the second surface, and guiding an inner surface of the first rotating body toward the nip portion; a second guide portion provided on the other side of the nip portion in the short side direction, extending to an opposite side of the second rotating body in the thickness direction with respect to the second surface, and guiding an inner surface of the first rotating body that has passed through the nip portion; Further comprising: The rib portion is continuous in the short side direction from the first guide portion to the second guide portion.

4. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing roller.

5. the support member has a first portion extending in the short side direction, a second portion extending from one end of the first portion in the short side direction toward the holder member in the thickness direction, and a third portion extending from the other end of the first portion in the short side direction toward the holder member in the thickness direction, and abuts against the second surface of the holder member at tips of the second portion and the third portion, The second portion and the third portion of the support member are provided with a concave shape that is recessed in a direction away from the second surface in the thickness direction and extends in the short direction, The rib portion extends in the short direction through the inside of the concave shape.

5. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing roller.

6. The holder member includes: a first protruding portion provided on one end side of the first surface in the short side direction, protruding toward the second rotating body in the thickness direction compared to the first surface, and sliding against an inner surface of the first rotating body; a second protruding portion provided on the other end side of the first surface in the short side direction, protruding toward the second rotating body in the thickness direction compared to the first surface, and sliding against an inner surface of the first rotating body; the first protruding portion protrudes toward the second rotating body in the thickness direction relative to a surface that slides against an inner surface of the first rotating body of the nip forming unit, 6. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing roller.

7. The heater includes a substrate extending in the longitudinal direction and the lateral direction, and a resistive heating element formed on the substrate, the first rotating body is a cylindrical film, and is heated by non-radiative heat generated by the resistance heating element when electricity is applied to the heater; 7. The fixing device according to claim 1, wherein the fixing member is a fixing member having a fixing roller.

8. A first rotating body, a nip forming unit including an elongated heater and a holder member for holding the heater, the nip forming unit being disposed in an internal space of the first rotating body; a second rotor that is in pressure contact with the nip forming unit across the first rotor and forms a nip between the second rotor and the nip forming unit; a support member disposed in the internal space of the first rotor and supporting the nip forming unit; a fixing device for fixing an image on a recording material by heating the image on the recording material with the first rotating body heated by the heater while the recording material is nipped and conveyed between the first rotating body and the second rotating body at the nip portion, The holder member includes: a first surface that faces the second rotating body in a direction perpendicular to both a longitudinal direction of the heater and a conveying direction of the recording material in the nip portion, the first surface supporting the heater; a second surface facing the opposite side of the first surface in the vertical direction and facing the support member; and an upstream guide portion provided on an upstream side of the holder member in the conveying direction and extending toward an opposite side of the second rotating body in the direction perpendicular to the second surface, the upstream guide portion guiding an inner surface of the first rotating body toward the nip portion; a downstream guide portion provided on a downstream side of the holder member in the conveying direction and extending toward an opposite side of the second rotating body in the direction perpendicular to the second surface, the downstream guide portion guiding an inner surface of the first rotating body that has passed through the nip portion; a rib portion that is protruding from the second surface and extends in the conveying direction over a range that includes a range in which the first surface is provided, and that extends from the upstream guide portion to the downstream guide portion; having a hole penetrating from the first surface to the second surface is formed in the holder member, and a detection element for detecting a temperature of the heater is disposed in the hole; The rib portion is provided on both sides of the hole in the longitudinal direction. A fixing device comprising:

9. The support member has a first contact portion that contacts the holder member on one side of the heater in the transport direction, and a second contact portion that contacts the holder member on the other side of the heater in the transport direction, and supports the holder member against a pressing force received by the holder member from the second rotating body via the first rotating body and the heater. The fixing device according to claim 8 .

10. From one end of the rib portion to the other end in the conveying direction, the width of the rib portion in the longitudinal direction is constant, and the height of the rib portion in the vertical direction is constant.

10. The fixing device according to claim 8, wherein the fixing member is a fixing member having a fixing surface.

11. The support member has a first portion extending in the conveying direction, a second portion extending from one end of the first portion in the conveying direction toward the holder member in the perpendicular direction, and a third portion extending from the other end of the first portion in the conveying direction toward the holder member in the perpendicular direction, and the second and third portions abut against the second surface of the holder member at their tips; The second portion and the third portion of the support member are provided with a concave shape that is recessed in a direction away from the second surface in the vertical direction and extends in the transport direction, The rib portion extends in the conveying direction through the inside of the concave shape.

11. The fixing device according to claim 8, wherein the fixing member is a fixing member having a fixing roller.

12. The holder member is a first protrusion provided on one end side of the first surface in the conveying direction, protruding toward the second rotating body in the perpendicular direction compared to the first surface, and sliding against an inner surface of the first rotating body; a second protruding portion provided on the other end side of the first surface in the conveying direction, protruding toward the second rotating body in the perpendicular direction compared to the first surface, and sliding against an inner surface of the first rotating body; the first protrusion protrudes toward the second rotor in the vertical direction relative to a surface that slides against an inner surface of the first rotor of the nip forming unit, 12. The fixing device according to claim 8, wherein the fixing member is a fixing member having a fixing roller.

13. The heater has a substrate extending in the longitudinal direction and the transport direction, and a resistive heating element formed on the substrate, the first rotating body is a cylindrical film, and is heated by non-radiative heat generated by the resistance heating element when electricity is applied to the heater; 13. The fixing device according to claim 8, wherein the fixing member is a fixing member having a fixing roller.

14. Further comprising a temperature control means for controlling a temperature of the heater based on a signal from the detection element. The fixing device according to claim 1 .

15. Further comprising a cut-off means for cutting off the power supply to the heater based on a signal from the detection element. The fixing device according to claim 1 .

16. The rib portion is arranged, with respect to the longitudinal direction, inside an area where the heater generates heat and outside an area where a recording material having a width in the longitudinal direction smaller than a recording material having a width in the longitudinal direction that is the largest among recording materials on which the fixing device can fix an image passes. The fixing device according to claim 1 .

17. an image forming means for forming a toner image on a recording material; a fixing device according to claim 1 , which fixes a toner image formed by the image forming unit onto a recording material; An image forming apparatus comprising:

Images