Fixing device and image forming apparatus equipped with same

Abstract

To provide a fixation device which reduces heat transmission to a non-passage region of a fixation belt from a shielding member by securing a heat radiation path of the shielding member and provide an image formation apparatus.SOLUTION: A fixation device comprises: a rotatable endless fixation belt; a nip formation member which is arranged on the inner peripheral surface of the fixation belt; a pressure roller which is brought into pressure-contact toward the nip formation member from the outer side of the fixation belt and forms a fixation nip region between the fixation belt and itself; a heat source which is arranged on the inner side of the fixation belt and heats the fixation belt; a belt holding member which holds the end in the rotational shaft direction of the fixation belt in a rotatable manner; a shielding member which shields heat transmission to a sheet non-passage region of the fixation belt from the heat source; and a heat radiation member which is provided with the shielding member and radiates heat accumulating on the shielding member to a sheet passage region on the fixation belt.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a fixing device and an image forming apparatus including the same. [Background technology]

[0002] A known fixing device fixes a toner image to a sheet by pressing a pressure roller against the outside of a rotatable endless fixing belt, forming a fixing nip area between the fixing belt and the pressure roller using a nip forming member arranged on the inner surface of the fixing belt, and heating the sheet in the fixing nip area.

[0003] The fixing belt is divided into an area on the fixing belt where the sheet passes (passing area) and other areas (non-passing area). In the passing area, the heat of the fixing belt is taken away by the passage of the sheet, so heat is unlikely to accumulate. On the other hand, in the non-passing area, the sheet does not pass through to take away the heat of the fixing belt, so heat is likely to accumulate. In particular, when sheets are fixed continuously, the temperature of the non-passing area of ​​the fixing belt rises excessively.

[0004] Therefore, as disclosed in Patent Document 1, there exists a fixing device having a shielding member that blocks heat transfer from the heat source to the non-passing area of ​​the fixing belt. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-164430 A Summary of the Invention [Problem to be solved by the invention]

[0006] The heat shielded by the shielding member is gradually dissipated from the surface of the shielding member. The heat dissipated from the shielding member is transferred to the fixing belt through the internal space of the fixing belt. When excessive heat accumulates in the shielding member, there is a concern that the fixing belt may overheat due to heat transfer from the shielding member. The above-mentioned conventional technology has a problem in that a sufficient heat dissipation path for the heat accumulated in the shielding member is not secured.

[0007] In particular, in the case of the miniaturized fixing belts of recent years, the internal space of the fixing belt has been reduced, resulting in the shielding member and the fixing belt being in close proximity to each other, and a structure that actively dissipates heat from the shielding member is required.

[0008] The present invention has been made to solve the above-mentioned problems in the conventional art, and aims to provide a fixing device that reduces heat transfer from the shielding member to non-passage areas of the fixing belt by ensuring a heat dissipation path for the shielding member, and an image forming apparatus equipped with such a fixing device. [Means for solving the problem]

[0009] In order to achieve the above object, a fixing device of the present invention includes a rotatable endless fixing belt, a nip forming member disposed on an inner circumferential surface of the fixing belt, a pressure roller that is pressed against the nip forming member from the outside of the fixing belt to form a fixing nip region between the fixing belt and the pressure roller, a heat source disposed on the inside of the fixing belt and that heats the fixing belt, a belt holding member that rotatably holds an end of the fixing belt in the rotation axis direction, and a shielding member that blocks heat transfer from the heat source to a sheet non-passing region of the fixing belt, the fixing device further includes a heat dissipation member that is attached to the shielding member and that dissipates heat accumulated in the shielding member to a sheet passing region on the fixing belt, the belt holding member has a shielding member holding portion that holds the shielding member, the shielding member has a locking claw that is locked to a locked portion of the shielding member holding portion, the shielding member holding portion has a shielding member holding groove into which the locking claw is inserted, and the locking claw is The shielding member is formed by bending the edge of the shielding member, and when the shielding member itself is subjected to a load in the bending direction, Under load 、The shielding member is inserted into the locked portion through the shielding member holding groove, The bending direction is not loaded. In a free state 、 The shielding member is characterized in that passage through the shielding member holding groove is obstructed.

[0010] In the fixing device, the heat dissipating member may have a through hole that allows heat to move from the heat source to a sheet passing area of ​​the fixing belt.

[0011] In the fixing device, the heat dissipating member may be formed in a mesh shape having through holes that allow heat to move from the heat source to a sheet passing area of ​​the fixing belt.

[0014] In the fixing device, the belt holding member may have a heat dissipation member holding portion that holds the heat dissipation member.

[0015] In the fixing device, the heat dissipating member may have a locking claw that is locked to the heat dissipating member holding portion.

[0016] In the fixing device, the shielding member and the heat dissipating member may be integrally formed.

[0017] In the fixing device, the shielding member and the heat dissipating member may be connected to each other.

[0018] In the fixing device, the shielding member and the heat dissipating member may be stacked on top of each other.

[0019] In the fixing device, the shielding member and the heat dissipating member may be made of different materials.

[0020] The image forming apparatus according to the present invention is characterized in that it is an image forming apparatus including the fixing device. Effect of the Invention

[0021] According to the present invention, it is possible to actively dissipate heat accumulated in the shielding member and to prevent overheating of the fixing belt due to heat transfer from the shielding member. [Brief description of the drawings]

[0022] [Figure 1] 1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus including a fixing device according to a first embodiment. [Figure 2A] 1 is a perspective view of a fixing device according to a first embodiment, viewed obliquely from above on the front side. [Figure 2B] 2 is a perspective view of the fixing device according to the first embodiment, seen obliquely from above on the rear side. FIG. [Diagram 3] FIG. 4 is a side view of the driving system of the pressure roller as viewed from the paper feed section side. [Figure 4A] FIG. 2 is a perspective view of the heat fixing unit and the pressure roller portion as viewed obliquely from above on the front side. [Figure 4B] FIG. 2 is a perspective view of the heat fixing unit and the pressure roller portion as viewed obliquely from above on the rear side. [Diagram 5] FIG. 2 is a perspective view showing a cross-sectional structure of a heat fixing unit and a pressure roller portion as viewed from the rear side. [Figure 6] FIG. 2 is a cross-sectional view of a heat fixing unit and a pressure roller portion as viewed from the rear side. [Figure 7] 11 is an end view showing a state in which the shielding member is held by a shielding member holding portion; FIG. [Figure 8A] 11A and 11B are end views showing schematic configurations of the shielding member and the heat dissipation member according to other examples. [Figure 8B] 13 is an end view showing a schematic diagram of still another example of the shielding member and the heat dissipation member. FIG. [Figure 9] 4 is a schematic vertical cross-sectional view of a part of the configuration of the heat fixing unit as viewed from the paper discharge unit side. FIG. [Figure 10A] FIG. [Figure 10B] FIG. [Figure 11]11 is an end view showing a schematic state in which the shielding member is held by a shielding member holding portion in the second embodiment. FIG. [Figure 12] 11 is a schematic vertical cross-sectional view of a part of the configuration of a heat fixing unit in a second embodiment, as viewed from the paper discharge unit side. FIG. [Figure 13] 13 is a diagram showing a schematic view of a locking claw of a shielding member in the second embodiment. FIG. [Figure 14] 13 is an end view showing a schematic state in which a shielding member and a heat dissipating member are held by a holding portion in the third embodiment. FIG. [Figure 15] 13 is a diagram illustrating a schematic view of a locking claw of a heat dissipation member in embodiment 3. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. In the following description, the same parts are given the same reference numerals, and the names and functions of the parts are also the same. Therefore, detailed description of the parts is omitted.

[0024] (Embodiment 1) -Overall configuration of image forming apparatus- 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 100 including a fixing device 200 according to embodiment 1. In the figure, the symbol X indicates the width direction (front-rear direction), the symbol Y indicates the left-right direction Y perpendicular to the width direction X, and the symbol Z indicates the up-down direction.

[0025] As shown in FIG. 1, the image forming apparatus 100 includes a photoconductor drum 10 acting as an image carrier, a charging device 90, an exposure device 30, a developing device 40, a transfer device 50, a cleaning device 60, and a fixing device 200. The charging device 90 charges the surface 10a of the photoconductor drum 10. The exposure device 30 exposes the photoconductor drum 10 charged by the charging device 90 to form an electrostatic latent image. The developing device 40 develops the electrostatic latent image formed by the exposure device 30 to form a toner image. The transfer device 50 transfers the toner image formed by the developing device 40 onto a sheet P such as a recording paper. The cleaning device 60 removes and collects toner remaining on the photoconductor drum 10. The fixing device 200 fixes the toner image transferred by the transfer device 50 onto the sheet P transported in the transport direction F to form an image. In this example, the image forming apparatus 100 is a monochrome printer (specifically, a laser printer). The image forming apparatus 100 may be, for example, a color image forming apparatus of an intermediate transfer type capable of forming a color image. Also, although the image forming apparatus 100 is a printer in this example, it may be, for example, a copier, a multifunction machine, or a facsimile machine.

[0026] The photosensitive drum 10 has a base 11 supported for free rotation on a main body frame (not shown) of the image forming apparatus 100, and is driven to rotate in a predetermined first rotation direction G1 (clockwise in the figure) around a rotation axis γ by a driving means not shown.

[0027] The charging device 90 includes a charging member 91. The charging member 91 uniformly charges the surface 10a of the photoconductor drum 10 to a predetermined potential by a high-voltage application device 92. In this example, the charging member 91 is a charging roller, which rotates in a second rotation direction G2 following the rotation of the photoconductor drum 10. The charging member 91 may be a charging charger.

[0028] The exposure device 30 repeatedly scans the surface 10a of the photoconductor drum 10, which is driven to rotate, with light modulated based on image information in the direction of the rotation axis γ of the photoconductor drum 10, which is the main scanning direction. The developing device 40 includes a developing roller 41 and a developing tank 42. The developing roller 41 supplies a developer DV to the surface 10a of the photoconductor drum 10. The developing tank 42 contains the developer DV. The transfer device 50 includes a transfer member 51. The transfer device 50 applies a predetermined high voltage to a transfer nip area TN formed between the photoconductor drum 10 and the transfer device 50 by a high voltage application device 52. The transfer member 51 is a transfer roller in this example, and rotates in a second rotation direction G2 in response to the rotation of the photoconductor drum 10. The transfer member 51 may be a transfer charger.

[0029] The cleaning device 60 includes a cleaning blade 61 and a recovery casing 62. The cleaning blade 61 removes toner remaining on the surface 10a of the photoconductor drum 10. The recovery casing 62 accommodates the toner removed by the cleaning blade 61. The fixing device 200 includes a heat fixing section 210 (heat fixing unit) and a pressure roller 220. The pressure roller 220 forms a fixing nip area FN together with the heat fixing section 210. A detailed configuration of the fixing device 200 will be described later. The image forming apparatus 100 also includes a housing 80 that accommodates the various components that make up the image forming apparatus 100.

[0030] - Fixing device - FIG. 2A is a perspective view of the fixing device 200 in this embodiment, viewed obliquely from above the front side. FIG. 2B is a perspective view of the fixing device 200 in this embodiment, viewed obliquely from above the rear side. FIG. 3 is a right side view of the drive system for the pressure roller 220 in the fixing device 200, viewed from the paper feed section 95 side. FIG. 4A is a perspective view of the heat fixing section 210 and the pressure roller 220, viewed obliquely from above the front side. FIG. 4B is a perspective view of the heat fixing section 210 and the pressure roller 220, viewed obliquely from above the rear side. FIG. 5 is a perspective view showing a cross-sectional structure of the heat fixing section 210 and the pressure roller 220, viewed from the rear side. Also, FIG. 6 is a cross-sectional view of the heat fixing section 210 and the pressure roller 220, viewed from the rear side. In FIG. 4A and FIG. 4B, the fixing belt 211 is omitted.

[0031] In the figure, the symbol W indicates the direction of the rotation axis of the fixing belt 211, with the -W direction (negative W direction) being the axial front direction and the +W direction (positive W direction) being the axial rear direction. In this embodiment, the W direction is aligned with the X direction.

[0032] Fixing device 200 includes a heat fixing section 210, a pressure roller 220, a front frame 230 (side plate), a rear frame 240 (side plate), a drive transmission mechanism 250, a rotation drive section 260, and a peeling member 270 (see FIGS. 2A to 6). Each component of fixing device 200 will be described in detail below.

[0033] <Heat fixing section> Heat fixing unit 210 has fixing belt 211, nip forming member 212, heat source 213, reflecting member 214, supporting member 215, sliding sheet 216, shielding members (217, 218), and heat dissipation member 219 (see FIGS. 4A to 6). Heat fixing unit 210 has a role of fixing toner by heat onto sheet P sandwiched between itself and pressure roller 220, which will be described later.

[0034] The fixing belt 211 is an endless (cylindrical) heat-resistant belt, and is rotatably supported at its front end and rear end by a front upper frame 231 and a rear upper frame 241, which will be described later. The fixing belt 211, together with a pressure roller 220, which will be described later, has a role of sandwiching and transporting the sheet P from the paper feed section 95 toward the paper discharge section 96 (in the direction F).

[0035] Specifically, the fixing belt 211 is a metal or polyimide (PI) base having a predetermined thickness (for example, about 30 μm to 100 μm) on which a silicone rubber layer having a predetermined thickness (for example, about 100 μm to 300 μm) is formed, and a fluororesin layer having a predetermined thickness (for example, about 20 μm to 30 μm) is further formed on the upper layer. This fluororesin layer is formed by, for example, laminating PFA tubes or applying fluororesin. In this embodiment, the fixing belt 211 is a silicone rubber top layer on which a PFA tube is provided. In this embodiment, the width of the fixing belt 211 along the rotation axis direction (W direction) is set to 340 mm.

[0036] The surface of the fixing belt 211 is defined in the W direction into a sheet passing area α and sheet non-passing areas (β1, β2) (see FIG. 3).

[0037] The sheet passing area α is an area on the fixing belt 211 through which the sheet P can pass by being conveyed. Specifically, the sheet passing area α is set to a size sufficient for the largest sheet that can pass through in the direction along its long side (so-called vertical feed direction) in the rotation axis direction of the fixing belt 211. In this embodiment, since the largest sheet that can pass through is an A3 size sheet, the width of the sheet passing area α along the W direction is set to be equal to the short side (297 mm) of an A3 size sheet in the rotation axis direction of the fixing belt 211.

[0038] The sheet non-passage areas (β1, β2) refer to areas other than the sheet passing area α on the surface of the fixing belt 211. The sheet non-passage area β1 is located in front of the sheet passing area α, and the sheet non-passage area β2 is located behind the sheet passing area α. In this embodiment, the widths of the sheet non-passage area β1 and the sheet non-passage area β2 along the W direction are each set to 21.5 mm ((340-297) / 2=21.5) based on the width of the fixing belt 211 and the width of the sheet passing area α described above.

[0039] The nip forming member 212 is disposed on an inner circumferential surface 211a of the fixing belt 211 (see FIGS. 5 and 6). The nip forming member 212 serves to form a fixing nip area FN between the fixing belt 211 and a pressure roller, which will be described later.

[0040] The nip forming member 212 is formed from a high-rigidity heat-resistant resin material (e.g., liquid crystal polymer (LCP), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), etc.) or a high-elasticity heat-resistant resin material (e.g., rubber material). The nip forming member 212 may be formed from a high-rigidity heat-resistant resin material on which an elastic layer (e.g., a rubber layer such as silicone rubber) is provided. In this embodiment, the nip forming member 212 is formed from a liquid crystal polymer having a thickness of 4.5 mm and a width of 15 mm in the short side direction S perpendicular to the W direction.

[0041] The heat source 213 is built into the fixing belt 211 (see FIGS. 5 and 6). The heat source 213 serves to heat the fixing belt 211 from the inside.

[0042] A front end of the heat source 213 is fixed to the front upper frame 231 via a front lamp support portion 231p, and a rear end of the heat source 213 is fixed to the rear upper frame 241 via a rear lamp support portion 241p (see FIGS. 4A and 4B). In this embodiment, a lamp heater is used as the heat source 213.

[0043] The reflecting member 214 is bent to conform to the shape of the supporting member 215 (described later) and is provided on the surface of the supporting member 215 facing the heat source 213 (see FIGS. 5 and 6). The reflecting member 214 has a role of reflecting the heat radiation from the heat source 213 toward the fixing belt 211.

[0044] The reflecting member 214 is a plate-shaped metal material such as aluminum. The surface of the reflecting member 214 is mirror-finished to efficiently reflect the heat radiation from the heat source 213 to the fixing belt 211.

[0045] Support member 215 is formed in an inverted T-shape in cross section seen from the W direction, and extends along the W direction (see FIG. 5). Support member 215 serves to support nip forming member 212 from the inside of fixing belt 211. Nip forming member 212 is fixed to the bottom surface of support member 215.

[0046] The sliding sheet 216 is provided between the fixing belt 211 and the nip forming member 212 (see FIGS. 5 and 6). The sliding sheet 216 is formed, for example, from a glass fiber material (for example, glass cloth) coated with a fluororesin such as PTFE (Polytetrafluoroethylene) (for example, a glass cloth sheet). The thickness of the sliding sheet 216 is set, for example, to about 0.1 mm to 0.5 mm. In this embodiment, the thickness of the sliding sheet 216 is set to 0.13 mm. The sliding sheet 216 and the nip forming member 212 are bonded to each other by an adhesive or an adhesive member.

[0047] Fig. 7 is an end view showing a state in which the shielding members (217, 218) are held by the shielding member holding portions (231c, 241c). Fig. 8A is an end view showing another example of the configuration of the shielding members (217, 218) and the heat dissipation member 219. Fig. 8B is an end view showing yet another example of the shielding members (217, 218) and the heat dissipation member 219. Fig. 9 is a schematic vertical cross-sectional view of a part of the configuration of the heat fixing unit 210 as viewed from the paper discharge unit 96 side.

[0048] A pair of front and rear shielding members (217, 218) are provided between the heat source 213 and the fixing belt 211 in the sheet non-passage areas (β1, β2) (see FIG. 7). The shielding members (217, 218) serve to block heat transfer from the heat source 213 to the fixing belt 211. The shielding members (217, 218) have a front shielding member 217 and a rear shielding member 218 (see FIGS. 4A and 4B). The front shielding member 217 is provided on the front end side of the fixing belt 211, i.e., in the sheet non-passage area β1, between the heat source 213 and the fixing belt 211 (see FIGS. 4A, 4B, 5, and 7). The rear shielding member 218 is provided on the rear end side of the fixing belt 211, that is, in the sheet non-passage area β2, between the heat source 213 and the fixing belt 211 (see FIGS. 4A, 4B, 5, and 7).

[0049] The front shielding member 217 and the rear shielding member 218 are formed in a quarter-circle dome shape. The front shielding member 217 is fixed by a front upper frame 231, which will be described later, and the rear shielding member 218 is fixed by a rear upper frame 241, which will be described later (see Figs. 4A and 4B). In this embodiment, the width of the front shielding member 217 and the rear shielding member 218 along the W direction is set to 24 mm based on the width (21.5 mm) of the above-mentioned sheet non-passage region β1 and sheet non-passage region β2 so as to reliably block heat transfer from the heat source 213 to the sheet non-passage region β1 or the sheet non-passage region β2.

[0050] Both the front shielding member 217 and the rear shielding member 218 are made of a metal material (e.g., stainless steel, aluminum, copper, etc.) having a predetermined thickness (e.g., 0.1 mm) formed into a plate shape. In this embodiment, the front shielding member 217 and the rear shielding member 218 are made of SUS430.

[0051] In this embodiment, the sheet non-passage region (β1, β2) has a sheet non-passage region β1 and a sheet non-passage region β2 separated by the sheet passing region α, and therefore a front shielding member 217 and a rear shielding member 218 are provided corresponding to the sheet non-passage region β1 and the sheet non-passage region β2, respectively. Of course, this is not limited to the above, and for example, when the sheet non-passage region has a single region or multiple adjacent regions, a single shielding member may be provided, while when the sheet non-passage region has multiple separated regions, three or more shielding members may be provided.

[0052] The heat dissipation member 219 is attached to the shielding members (217, 218) between the heat source 213 and the fixing belt 211 so as to face the sheet passing area α of the fixing belt 211 (see FIG. 7). The heat dissipation member 219 has a role of dissipating heat from the shielding members (217, 218) to the sheet passing area α side.

[0053] The heat dissipation member 219 is a plate made of a metal material (for example, stainless steel, aluminum, copper, etc.) having a predetermined thickness (for example, 0.1 mm). In this embodiment, the heat dissipation member 219 is made of SUS430.

[0054] The heat dissipation member 219 is connected to the front shielding member 217 and the rear shielding member 218 (see FIGS. 4A, 4B, 5, and 7). The heat dissipation member 219 is formed in a quarter-circle dome shape along the shapes of the front shielding member 217 and the rear shielding member 218, and is fixed by the support members 215 at both ends (219b, 219c) in the circumferential direction of the fixing belt 211.

[0055] In this embodiment, the heat dissipation member 219 is provided with a large number of through holes 219a in a mesh pattern (see FIGS. 4A and 4B) that allow heat to transfer from the heat source 213 to the sheet passing area α of the fixing belt 211. The through holes 219a are formed by, for example, punching or etching. The through holes 219a correspond to the transparent holes recited in the claims.

[0056] By providing such through holes 219a in the heat dissipation member 219, an effect is achieved in that the fixing belt 211 is efficiently heated in the sheet passing area α by the heat passed through the through holes 219a.

[0057] In addition, since the through holes 219a are formed in a mesh pattern, more paths for heat transfer from the heat source 213 to the fixing belt 211 are secured in the sheet passing area α, resulting in an effect that the fixing belt 211 is heated more efficiently.

[0058] In this embodiment, the heat dissipation member 219 is integrally formed with the shielding members (217, 218), which reduces the number of parts and reduces assembly costs.

[0059] Of course, the heat dissipation member 219 is not limited to being integrally formed with the shielding members (217, 218), and may be made of a material different from that of the shielding members (217, 218) or may be formed separately from the shielding members (217, 218) (see FIGS. 8A and 8B). The heat dissipation member 219 may be connected to the inside of the shielding members (217, 218) (see FIG. 8A) or to the outside of the shielding members (217, 218) (see FIG. 8B). In short, it is sufficient that the heat dissipation member 219 is attached to the shielding members (217, 218) to allow heat transfer from the shielding members (217, 218) to the heat dissipation member 219 and dissipate the heat to the sheet passing area α side via the heat dissipation member 219.

[0060] Furthermore, by providing such heat dissipation member 219 between heat source 213 and fixing belt 211 , it is possible to protect fixing belt 211 from contact with heat source 213 .

[0061] <Pressure roller> The pressure roller 220 is rotatably supported at its front end and rear end by a forward moving member 232b or a rear moving member 242b described later, and is rotationally driven by a rotational driving force of a rotation drive unit 260 (driving motor) described later. The pressure roller 220 has a role of nipping and conveying the sheet P from the paper feed unit 95 to the paper discharge unit 96 (in the F direction) together with the fixing belt 211 while being pressed against the nip forming member 212 from the outside of the fixing belt 211.

[0062] The pressure roller 220 is formed by forming an elastic member (a rubber member such as sponge rubber or solid rubber, such as silicone rubber) of a predetermined thickness (for example, about 6 mm) and a hardness of about 35 degrees to 40 degrees on a base made of a metal such as aluminum, and further forming a fluororesin layer on the upper layer of the elastic member. This fluororesin layer is formed by, for example, laminating PFA tubes or applying fluororesin. In this embodiment, the pressure roller 220 is formed by providing a PFA tube on the elastic member.

[0063] <Front and rear frames> Fig. 10A is a rear view showing the front belt holding member 231a, and Fig. 10B is a front view showing the rear belt holding member 241a.

[0064] The front frame 230 has a front upper frame 231, a front lower frame 232, and a connecting portion 233 (see FIGS. 2A and 2B). The front upper frame 231 and the front lower frame 232 are connected vertically by the connecting portion 233.

[0065] The rear frame 240 has a rear-upper frame 241, a rear-lower frame 242, and a connecting portion 243 (see FIGS. 2A and 2B). The rear-upper frame 241 and the rear-lower frame 242 are connected vertically by the connecting portion 243.

[0066] The front frame 230 and the rear frame 240 rotatably support the front and rear ends of the fixing belt 211 and the pressure roller 220, respectively, and also support other components (such as the heat source 213) arranged inside the fixing belt 211.

[0067] The front upper frame 231 has a front belt holding member 231a and a front lamp support portion 231p, and the rear upper frame 241 has a rear belt holding member 241a and a rear lamp support portion 241p (see Figures 2A, 2B, 4A and 4B).

[0068] The front belt holding member 231a has a front belt sliding contact portion 231b and a front shielding member holding portion 231c, and the rear belt holding member 241a has a rear belt sliding contact portion 241b and a rear shielding member holding portion 241c (see Figures 10A and 10B).

[0069] The front belt sliding contact portion 231b is provided in a semi-ring shape on the +W direction side of the front belt sliding contact portion 231b, and the rear belt sliding contact portion 241b is provided in a semi-ring shape on the -W direction side of the rear belt holding member 241a (see FIGS. 4A and 4B). The front belt holding member 231a and the rear belt holding member 241a have the role of supporting the fixing belt 211 so as to be freely rotatable by bringing the front belt sliding contact portion 231b and the rear belt sliding contact portion 241b into sliding contact with the inner sides of the front end portion and the rear end portion of the fixing belt 211, respectively. The front belt sliding contact portion 231b and the rear belt sliding contact portion 241b are both provided so that the sliding contact surface with the fixing belt 211 faces the opposite side to the fixing nip area FN.

[0070] The front shielding member holding portion 231c is provided on the inner circumferential side of the front belt sliding contact portion 231b, and the rear shielding member holding portion 241c is provided on the inner circumferential side of the rear belt sliding contact portion 241b (see Figs. 10A and 10B). The front shielding member holding portion 231c has a role of holding the front shielding member 217. The rear shielding member holding portion 241c has a role of holding the rear shielding member 218. The front shielding member holding portion 231c has an outer tab 231d, an inner tab 231e, and a front shielding member holding groove 231f, and the rear shielding member holding portion 241c has an outer tab 241d, an inner tab 241e, and a rear shielding member holding groove 241f (see Figs. 10A and 10B). The outer tab 231d and the inner tab 231e are both provided in a quarter-circle half-ring shape protruding from the +W direction side of the front belt sliding contact part 231b, and are spaced apart at a predetermined interval. The outer tab 241d and the inner tab 241e are both provided in a quarter-circle half-ring shape protruding from the -W direction side of the rear belt holding member 241a, and are spaced apart at a predetermined interval. The front shielding member holding groove 231f is a groove formed by the outer tab 231d and the inner tab 231e, and the rear shielding member holding groove 241f is a groove formed by the outer tab 241d and the inner tab 241e (see Figs. 10A and 10B). The front shielding member 217 is inserted into the front shielding member holding groove 231f. The rear shielding member 218 is inserted into the rear shielding member holding groove 241f. The front shielding member holding groove 231f is formed in a curved shape that follows the shape of the front shielding member 217 in a cross-sectional view seen from the W direction. The rear shielding member holding groove 241f is formed in a curved shape that follows the shape of the rear shielding member 218 in a cross-sectional view seen from the W direction.

[0071] In this embodiment, the outer tabs (231d, 241d) and the inner tabs (231e, 241e) are both set to a length of 10 mm along the W direction. The lengths of the outer tabs (231d, 241d) and the inner tabs (231e, 241e) are set to a length sufficient for holding the shielding members (217, 218). In addition, the groove width of the shielding member holding grooves (231f, 241f) is set to a size sufficient for the shielding members (217, 218) to be inserted therein and sufficient to prevent the shielding members (217, 218) from falling off.

[0072] By providing such a front shielding member holding portion 231c on the front belt holding member 231a and providing the rear shielding member holding portion 241c on the rear belt holding member 241a, the effect is achieved that the shielding members (217, 218) are stably held between the heat source 213 and the sheet non-passage areas (β1, β2).

[0073] The front lamp support portion 231p and the rear lamp support portion 241p are arranged outside the front belt holding member 231a (or the rear belt holding member 241a) for the purpose of supporting the front end portion (or the rear end portion) of the heat source 213 (see Figures 2A, 2B, 4A and 4B).

[0074] The front lower frame 232 has a front lower frame main body 232a and a front moving member 232b, and the rear lower frame 242 has a rear lower frame main body 242a and a rear rotating member 242b (see Figs. 2A and 2B). The front moving member 232b and the rear rotating member 242b are each supported by a rotating shaft (not shown) to be rotatable about a rotation axis δ with respect to the front lower frame main body 232a (or the rear lower frame main body 242a). The front moving member 232b and the rear rotating member 242b each have a role of rotatably supporting the front end (or the rear end) of the pressure roller 220. The front moving member 232b is urged toward the fixing belt 211 by the urging member 234, and the rear rotating member 242b is urged toward the fixing belt 211 by the urging member 244. The pressure roller 220 is pressed against the fixing belt 211 by the biasing force of the biasing members (234, 244).

[0075] <Drive transmission mechanism and rotation drive unit> The drive transmission mechanism 250 has a drive gear 251 and a driven gear 252 (see FIG. 3). The drive gear 251 is fixed to a rotation shaft 261 of the rotation drive unit 260. The driven gear 252 is fixed to a rotation shaft 220a of the pressure roller 220 in a state of meshing with the drive gear 251. By driving the rotation drive unit 260, the pressure roller 220 is rotationally driven in the second rotation direction G2 via the drive transmission mechanism 250.

[0076] <Removal material> The peeling member 270 is a peeling plate provided near the fixing belt 211 in the paper discharge unit 96 (see FIG. 6). The peeling member 270 peels the sheet P that has passed between the fixing belt 211 and the pressure roller 220 from the fixing belt 211, and prevents the sheet P from wrapping around the fixing belt 211.

[0077] Next, the radiation path of heat accumulated in the shielding members (217, 218) from the heat source 213 will be described.

[0078] The heat generated by the heat source 213 moves toward the fixing belt 211. At this time, the heat moving from the heat source 213 toward the sheet non-passing region β1 of the fixing belt 211 is blocked by the front shielding member 217 arranged on the path of the heat transfer. The heat moving from the heat source 213 toward the sheet non-passing region β2 of the fixing belt 211 is blocked by the rear shielding member 218 arranged on the path of the heat transfer. The front shielding member 217 and the rear shielding member 218 are heated by the heat from the heat source 213, and the heat accumulates in the front shielding member 217 and the rear shielding member 218. The heat of the front shielding member 217 and the rear shielding member 218 moves to the heat dissipation member 219 attached to the front shielding member 217 and the rear shielding member 218. The heat accumulated in the front shielding member 217 is conducted to the +W direction side, i.e., the sheet passing area α side, via the heat dissipation member 219, and is dissipated from the surface of the heat dissipation member 219. Similarly, the heat accumulated in the rear shielding member 218 is conducted to the -W direction side, i.e., the sheet passing area α side, via the heat dissipation member 219, and is dissipated from the surface of the heat dissipation member 219. Since the heat dissipation member 219 is provided to face the sheet passing area α of the fixing belt 211, the heat dissipated from the surface of the heat dissipation member 219 moves to the sheet passing area α of the fixing belt 211.

[0079] Therefore, by providing such a heat dissipation member 219, the heat that is blocked from moving to the sheet non-passage areas (β1, β2) by the shielding members (217, 218) is moved from the sheet non-passage areas (β1, β2) to the sheet passage area α via the heat dissipation member 219, and is dissipated to the sheet passage area α of the fixing belt 211.

[0080] (Embodiment 2) Fig. 11 is an end view showing a state in which the shielding members (217, 218) in the second embodiment are held by the shielding member holding portions (231c, 241c). Fig. 12 is a schematic vertical cross-sectional view of a part of the configuration of the heat fixing portion 210 in the second embodiment, seen from the paper discharge portion 96 side. Fig. 13 is a diagram showing a locking claw 700 of the shielding members (217, 218) in the second embodiment.

[0081] In the second embodiment, the shielding member holding portions (231c, 241c) further include locked portions (231g, 241g) in addition to the shielding member holding portions (231c, 241c) in the first embodiment (see FIG. 11). The front shielding member holding portion 231c is provided with the locked portion 231g, and the rear shielding member holding portion 241c is provided with the locked portion 241g. A locking claw 700 of the shielding members (217, 218), which will be described later, is locked to the locked portion 231g and the locked portion 241g, respectively. The locked portion 231g is recessed into the outer periphery of the front shielding member 217 at the rear of the front shielding member holding groove 231f, and the locked portion 241g is recessed into the outer periphery of the rear shielding member 218 at the rear of the rear shielding member holding groove 241f (see Figure 11).

[0082] In the second embodiment, the shielding members (217, 218) further have a locking claw 700 (see FIG. 11) in addition to the shielding members (217, 218) in the first embodiment. The locking claw 700 that is locked to the locked portion 231g is provided on the edge on the -W direction side of the front shielding member 217, and the locking claw 700 that is locked to the locked portion 241g is provided on the edge on the +W direction side of the rear shielding member 218.

[0083] The locking claw 700 is formed by bending a segment 703 formed between two slits 701 and 702 arranged approximately parallel to the edge of the shielding member (217, 218) so that the segment 703 faces the outer periphery of the shielding member (217, 218) (see Figures 11 and 13).

[0084] The locking claw 700 is inserted from the shielding member holding groove (231f, 241f) into the locked portion (231g, 241g) when it is further loaded in the bending direction from the free state. The locking claw 700 returns to the free state in the locked portion (231g, 241g). The shape of the locking claw 700 is set so that it can pass through the shielding member holding groove (231f, 241f) in the loaded state, but has difficulty passing through the shielding member holding groove (231f, 241f) in the free state.

[0085] By providing such a locking claw 700 on the shielding member (217, 218), the shielding member (217, 218) is more stably held by the shielding member holding portion (231c, 241c) between the heat source 213 and the sheet non-passage area (β1, β2).

[0086] The shapes of the locked portions (231g, 241g) and the locking claws 700 are not limited to those described above, and any shapes are sufficient as long as they can prevent the shielding members (217, 218) from coming off the shielding member holding portions (231c, 241c). The locking claws 700 may be formed separately from the shielding members (217, 218), or multiple locking claws 700 may be provided on the shielding members (217, 218).

[0087] In the second embodiment, the heat dissipation member 219 is provided with a first through hole 219d, a second through hole 219e, and a third through hole 219f that allow heat transfer from the heat source 213 to the sheet passing area α of the fixing belt 211 (see FIG. 12). The first through hole 219d, the second through hole 219e, and the third through hole 219f are each formed along the W direction. A first protective frame 219g is formed between the first through hole 219d and the second through hole 219e, and a second protective frame 219h is formed between the second through hole 219e and the third through hole 219f (see FIG. 12).

[0088] By providing such first through hole 219d, second through hole 219e, and third through hole 219f, it becomes possible to pass heat from the heat source 213 through the first through hole 219d, second through hole 219e, and third through hole 219f in the sheet passing area α and to efficiently heat the fixing belt 211. In addition, by providing such first protective frame 219g and second protective frame 219h, it becomes possible to protect the fixing belt 211 from contact with the heat source 213.

[0089] (Embodiment 3) Fig. 14 is an end view showing a state in which the shielding members (217, 218) and the heat dissipation member 219 are held by the holding portions (231h, 241h) in the third embodiment. Fig. 15 is a diagram showing a locking claw 900 of the heat dissipation member 219 in the third embodiment.

[0090] In the third embodiment, the shielding members (217, 218) are each connected to an inner circumferential surface of a heat dissipation member 219 (see FIG. 14). The front shielding member 217 is connected to an end of the heat dissipation member 219 on the -W direction side (see FIG. 14). The rear shielding member 218 is connected to an end of the heat dissipation member 219 on the +W direction side (see FIG. 14).

[0091] In the third embodiment, the shielding members (217, 218) are connected to the heat dissipation member 219 by being held together with the heat dissipation member 219 by holding portions (231h, 241h) described below. Of course, this is not limited to the above, and the shielding members (217, 218) may be connected to the heat dissipation member 219 by welding, or may be connected to the heat dissipation member 219 via an adhesive or bonding member.

[0092] Because the shielding member (217, 218) and the heat dissipation member 219 are connected to each other, even if the shielding member (217, 218) and the heat dissipation member 219 are formed separately, the heat accumulated in the shielding member (217, 218) is conducted to the sheet passing area α via the heat dissipation member 219.

[0093] In the third embodiment, the shielding members (217, 218) are laminated in the plate thickness direction of the heat dissipation member 219 (see FIG. 14). Of course, the present invention is not limited to this, and the shielding members (217, 218) may be formed by plating applied to the heat dissipation member 219 (for example, copper plating coated with nickel plating, silver plating, etc.) and laminated on the heat dissipation member 219.

[0094] By stacking the shielding members (217, 218) in the thickness direction of the heat dissipation member 219, a larger contact area is ensured between the shielding members (217, 218) and the heat dissipation member 219 compared to a case in which the shielding members (217, 218) and the heat dissipation member 219 are connected together with their thickness surfaces facing each other, resulting in the effect that heat from the shielding members (217, 218) is more efficiently transferred to the heat dissipation member 219.

[0095] In the third embodiment, the shielding members (217, 218) are made of copper. The shielding members (217, 218) are electroless nickel plated for corrosion resistance. Since the shielding members (217, 218) are made of copper, which has better heat transfer properties than SUS430, it is expected that the shielding members (217, 218) will be able to more actively shield the fixing belt 211 from heat from the heat source 213, compared to when the shielding members (217, 218) are made of SUS430.

[0096] Moreover, in the third embodiment, the heat dissipation member 219 is made of aluminum. Since the heat dissipation member 219 is made of aluminum, which has better thermal conductivity than SUS430, it is expected that the heat dissipation member 219 can more actively transfer the heat accumulated in the shielding members (217, 218) to the sheet passing area α side, compared to when the heat dissipation member 219 is made of SUS430.

[0097] In this manner, by forming the shielding members (217, 218) and the heat dissipation member 219 from different materials, the effect of improving the efficiency of shielding heat from the heat source 213 and dissipating heat accumulated in the shielding members (217, 218) is achieved.

[0098] In the third embodiment, the shielding members (217, 218) further have a locking claw 700 (see FIG. 11) as in the second embodiment. The front shielding member 217 has a locking claw 700 on an edge on the -W direction side that is locked to the locked portion 231g, and the rear shielding member 218 has a locking claw 700 on an edge on the +W direction side that is locked to the locked portion 241g.

[0099] In the third embodiment, the heat dissipation member 219 extends from the front belt holding member 231a to the rear belt holding member 241a (see FIG. 14). In the third embodiment, the heat dissipation member 219 further includes a locking claw 900 that is locked to the locked portions (231g, 241g) in addition to the heat dissipation member 219 in the first embodiment (see FIG. 14). The locking claws 900 are provided on the edge of the heat dissipation member 219 on the -W direction side and the edge of the heat dissipation member 219 on the +W direction side, respectively.

[0100] The locking claw 900 is formed by bending a segment 903 formed between two slits 901 and 902 arranged approximately parallel to the edge of the heat dissipation member 219 so that the segment 903 faces the inner peripheral side of the heat dissipation member 219 (see Figures 14 and 15).

[0101] The locking claw 900 is inserted from the holding groove (231j, 241j) to the locked portion (231g, 241g) in a state where a load is applied from the free state in the bending direction. The locking claw 900 returns to the free state in the locked portion (231g, 241g). The shape of the locking claw 900 is set so that it can pass through the holding groove (231j, 241j) in a loaded state, but has difficulty passing through the holding groove (231j, 241j) in a free state.

[0102] The provision of such locking claws 900 has the effect of allowing the heat dissipation member 219 to be more stably held by the holding portions (231h, 241h) between the heat source 213 and the sheet passing area α.

[0103] The shapes of the locked portions (231g, 241g) and the locking claws 700 and 900 are not limited to those described above, and any shapes are sufficient as long as they can prevent the shielding members (217, 218) and the heat dissipation member 219 from coming off the holding portions (231h, 241h). The locking claws 700 may be formed separately from the shielding members (217, 218), or multiple locking claws 700 may be provided on the shielding members (217, 218). Similarly, the locking claws 900 may be formed separately from the heat dissipation member 219, or multiple locking claws 900 may be provided on the heat dissipation member 219.

[0104] In the third embodiment, the belt holding members (231a, 241a) are different from the belt holding members (231a, 241a) in the first embodiment in that they have holding portions (231h, 241h) instead of the shielding member holding portions (231c, 241c) (see FIG. 14). The holding portions (231h, 241h) correspond to the shielding member holding portion and the heat dissipation member holding portion recited in the claims.

[0105] The front holding portion 231h is provided on the inner circumferential side of the front belt sliding contact portion 231b, and the rear holding portion 241h is provided on the inner circumferential side of the rear belt sliding contact portion 241b. The front holding portion 231h has a role of holding the front shielding member 217 and the heat dissipation member 219, and the rear holding portion 241h has a role of holding the rear shielding member 218 and the heat dissipation member 219.

[0106] The holding portions (231h, 241h) have holding grooves (231j, 241j) instead of the shielding member holding grooves (231f, 241f) (see FIG. 14).

[0107] The front holding part 231h has an outer tab 231d, an inner tab 231e, and a front holding groove 231j (see FIG. 14). The rear holding part 241h has an outer tab 241d, an inner tab 241e, and a rear holding groove 241j (see FIG. 14). The outer tab 231d and the inner tab 231e are both provided in a protruding shape of a quarter circle half ring on the +W direction side of the front belt sliding contact part 231b, and are spaced apart at a predetermined interval. The outer tab 241d and the inner tab 241e are both provided in a protruding shape of a quarter circle half ring on the +W direction side of the rear belt holding member 241a, and are spaced apart at a predetermined interval.

[0108] The front holding groove 231j is a groove formed by the outer tab 231d and the inner tab 231e, and the rear holding groove 241j is a groove formed by the outer tab 241d and the inner tab 241e. The front shielding member 217 and the heat dissipation member 219 are inserted into the front holding groove 231j, and the rear shielding member 218 and the heat dissipation member 219 are inserted into the rear holding groove 241j. The front holding groove 231j is formed in a curved shape that follows the shape of the front shielding member 217 in a cross-sectional view seen from the W direction, and the rear holding groove 241j is formed in a curved shape that follows the shape of the rear shielding member 218 in a cross-sectional view seen from the W direction.

[0109] The groove width of the holding grooves (231j, 241j) is set to a size sufficient to insert the shielding members (217, 218) and the heat dissipation member 219 in a stacked state and to prevent the shielding members (217, 218) and the heat dissipation member 219 from falling off.

[0110] By providing such holding portions (231h, 241h) on the belt holding members (231a, 241a), an effect is achieved in that the heat dissipation member 219 is stably held between the heat source 213 and the sheet passing area α.

[0111] The front holding portion 231h is provided with a locked portion 231g, and the rear holding portion 241h is provided with a locked portion 241g. A locking claw 700 of the shielding member (217, 218) and a locking claw 900 of the heat dissipation member 219 are locked to the locked portion 231g and the locked portion 241g, respectively.

[0112] The locked portion 231g has a first locked portion 231k recessed into the outer periphery of the front shielding member 217 at the back of the front holding groove 231j, and a second locked portion 231m recessed into the inner periphery of the front shielding member 217 at the back of the front holding groove 231j (see FIG. 14). The locked portion 241g has a first locked portion 241k recessed into the outer periphery of the rear shielding member 218 at the back of the rear holding groove 241j, and a second locked portion 241m recessed into the inner periphery of the rear shielding member 218 at the back of the rear holding groove 241j (see FIG. 14).

[0113] The locking claw 700 of the front shielding member 217 is inserted into the first locked portion 231k, and the locking claw 700 of the rear shielding member 218 is inserted into the first locked portion 241k. The locking claws 900 of the heat dissipation member 219 are inserted into the second locked portion 231m and the second locked portion 241m, respectively.

[0114] In addition, in the third embodiment, holding portions (231h, 241h) are provided to hold both the shielding members (217, 218) and the heat dissipation member 219, but of course this is not limited to this, and the portion for holding the shielding members (217, 218) and the portion for holding the heat dissipation member 219 may be provided separately.

[0115] The above-mentioned embodiment is illustrative in all respects and is not intended to be a basis for a limiting interpretation. Therefore, the technical scope of the present invention is not interpreted only by the above-mentioned embodiment, but is defined based on the description of the claims. In addition, all modifications within the meaning and scope equivalent to the claims are included. [Explanation of symbols]

[0116] 100 Image forming device 200 Fixing device 210 Heat fixing unit 220 Pressure roller 211 Fixing belt 212 Nip forming member 213 Heat source 214 Reflective material 215 Support member 216 Sliding Sheet 217 Front shielding member 218 Rear shielding member 219 Heat dissipation materials 230 Previous Frame 231a Front belt retaining member 231b Front belt sliding part 231c Front shielding member holding part 231f Front shielding member holding groove 231h Front holding part 231j Front holding groove 240 Rear Frame 241a Rear belt retaining member 241b Rear belt sliding part 241c rear shielding member holding part 241f Rear shielding member holding groove 241h Rear holding part 241j Rear retaining groove 250 Drive transmission mechanism 260 Rotation drive unit 270 Peeling member

Claims

1. a rotatable endless fixing belt; a nip forming member disposed on an inner circumferential surface of the fixing belt; a pressure roller that is pressed against the nip forming member from the outside of the fixing belt to form a fixing nip region between the fixing belt and the pressure roller; a heat source disposed inside the fixing belt and configured to heat the fixing belt; a belt holding member that rotatably holds an end portion of the fixing belt in a rotation axis direction; a shielding member that blocks heat transfer from the heat source to a sheet non-passing area of ​​the fixing belt; In a fixing device comprising: a heat dissipation member that is attached to the shielding member and dissipates heat accumulated in the shielding member to a sheet passing area on the fixing belt; the belt holding member has a shielding member holding portion that holds the shielding member, the shielding member has a locking claw that is locked to a locked portion of the shielding member holding portion, the shielding member holding portion has a shielding member holding groove into which the locking claw is inserted, The locking claw is formed by bending an edge of the shielding member, and when the locking claw is in a loaded state in which the locking claw is applied in a bending direction, the locking claw is inserted into the locked portion through the shielding member holding groove, and when the locking claw is in a free state in which the locking claw is not applied in the bending direction, the locking claw is prevented from passing through the shielding member holding groove. A fixing device comprising:

2. 2. The fixing device according to claim 1, The heat dissipating member has a through hole that allows heat to be transferred from the heat source to a sheet passing area of ​​the fixing belt.

3. 3. The fixing device according to claim 1, The fixing device, wherein the heat dissipating member is formed in a mesh shape having through holes that allow heat to move from the heat source to a sheet passing area of ​​the fixing belt.

4. 4. The fixing device according to claim 1, The fixing device, wherein the belt holding member has a heat dissipation member holding portion that holds the heat dissipation member.

5. The fixing device according to claim 4 , The fixing device according to claim 1, wherein the heat dissipating member has a locking claw that is locked to the heat dissipating member holding portion.

6. The fixing device according to any one of claims 1 to 5, The fixing device, wherein the shielding member and the heat dissipating member are integrally formed.

7. 7. The fixing device according to claim 1, The fixing device, wherein the shielding member and the heat dissipating member are connected to each other.

8. The fixing device according to claim 7 , The fixing device, wherein the shielding member and the heat dissipating member are stacked on top of each other.

9. 9. The fixing device according to claim 7, The fixing device, wherein the shielding member and the heat dissipating member are made of different materials.

10. 10. An image forming apparatus comprising the fixing device according to claim 1.

Images