JP7443698B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device and an image forming apparatus.

An electrophotographic image forming apparatus includes a fixing device that fixes a toner image onto a sheet of paper. The fusing device includes a fusing assembly and a pressure roller. A pressure roller presses the fuser assembly to form a fuser nip.

The fixing assembly described in Patent Document 1 includes a fixing film, a heater, a heat insulating holder, and a metal stay. The fixing film is cylindrical. The fixing film rotates as the pressure roller rotates. The heater contacts the inner surface of the fixing film and heats the fixing film. An insulated holder holds the heater. The metal stay presses the heat insulating holder against the pressure roller. The heat insulating holder described in Patent Document 1 has a plurality of ribs. Each of the plurality of ribs protrudes from the side wall of the heat insulating holder in a direction perpendicular to the width direction of the fixing film. The plurality of ribs are arranged at equal intervals along the width direction of the fixing film. Each of the plurality of ribs has the same height. The height of the rib indicates the length of each of the plurality of ribs protruding from the side wall of the heat insulating holder in the direction perpendicular to the width direction of the fixing film. The ribs maintain the shape of the fuser film as it rotates.

JP2017-97143A

However, unless the shape of the member disposed inside the fixing film is optimized, the center portion of the fixing film in the width direction may become depressed. If the dent in the widthwise center of the fixing film is large, cracks may occur in the fixing film due to the dent.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a fixing device and an image forming apparatus in which a fixing belt is not easily dented.

A fixing device according to the present invention includes a fixing belt, a heating section, and a belt holding section. The fixing belt is endless. The heating section faces an inner circumferential surface of the fixing belt. The belt holding section rotatably holds both ends of the fixing belt. The heating section includes a heater and a heater holding member. The heater heats the fixing belt. The heater holding member holds the heater. The heater holding member has a main body and a plurality of protrusions. The plurality of protrusions regulate the shape of the fixing belt. Each of the plurality of protrusions protrudes from the main body. The plurality of protrusions include a plurality of first protrusions and a plurality of second protrusions. The plurality of first protrusions are arranged in a central portion of the main body in the first direction where both ends of the fixing belt face each other. The plurality of second protrusions are arranged in a position different from the center portion of the main body portion. The belt holding section has a contact section that contacts the fixing belt. The fixing device satisfies (a) or (b). In the above (a), in a second direction perpendicular to the first direction, the maximum width of the contact portion is the same as the first maximum width, and the first maximum width is greater than or equal to the second maximum width. Show that. The first maximum width indicates the maximum width of the central portion of the heater holding member. The second maximum width indicates the maximum width of a region of the heater holding member where the plurality of second protrusions are arranged. The above (b) indicates that the maximum width of the contact portion is wider than the first maximum width, and the first maximum width is wider than the second maximum width in the second direction.

An image forming apparatus according to the present invention includes the fixing device and an image forming section. The image forming section forms a toner image on a recording medium. The fixing device fixes the toner image on the recording medium.

According to the fixing device and image forming apparatus of the present invention, the fixing belt is not easily dented.

1 is a diagram showing an image forming apparatus according to an embodiment of the present invention. 1 is a perspective view showing main parts of a fixing device according to an embodiment of the present invention. FIG. 1 is an exploded perspective view showing a fixing device according to an embodiment of the present invention. 3 is a sectional view taken along cutting line IV in FIG. 2. FIG. It is a perspective view of a pair of belt holding parts concerning an embodiment of the present invention. It is a perspective view of a heater holding member and a belt holding part concerning an embodiment of the present invention. It is a top view of the heater holding member and belt holding part based on embodiment of this invention. 8 is an enlarged view of region R in FIG. 7. FIG. (a) is a sectional view taken along cutting line IXA in FIG. 7. (b) is a sectional view taken along cutting line IXB in FIG. 7. (c) is a sectional view taken along cutting line IXC in FIG. 7. (a) is a partial sectional view taken along cutting line XA in FIG. 2. (b) is a partial cross-sectional view of the fixing belt and the protrusion according to the embodiment of the present invention at the center of the heater holding member in the Y-axis direction when the fixing device is in a stationary state. (a) is a partial cross-sectional view of the fixing belt and the protrusion according to the embodiment of the present invention at the center of the heater holding member in the Y-axis direction when the fixing device is in a driving state. (b) is a partial cross-sectional view of the central portion of the heater holding member in the Y-axis direction between the protrusion of the comparative example and the fixing belt in the driving state of the fixing device. (a) is an enlarged view of the first end of the heater holding member viewed from the Z-axis positive side. (b) is a diagram of the first end of the heater holding member viewed from the negative side of the X-axis. (a) is a sectional view showing a state in which the fixing belt is inserted into the heater holding member from the second end side of the heater holding member. (b) is a sectional view showing a state in which the fixing belt is inserted into the heater holding member.

Embodiments of the present invention will be described below with reference to the drawings. In addition, in the drawings, the same reference numerals are given to the same or corresponding parts, and the description will not be repeated. Furthermore, in this embodiment, the drawings show an X-axis, a Y-axis, and a Z-axis that are orthogonal to each other. The Z axis is parallel to the vertical plane, and the X and Y axes are parallel to the horizontal plane.

An image forming apparatus 100 according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram showing an image forming apparatus 100 according to this embodiment. The image forming apparatus 100 is, for example, a copying machine, a facsimile machine, or a multifunctional device having these functions. In this embodiment, the image forming apparatus 100 is a monochrome multifunction device.

As shown in FIG. 1, the image forming apparatus 100 includes a reading section 3, a document transport section 4, a paper feed section 5, a transport section 6, an image forming section 2, a fixing device 1, and a discharge section 7. Equipped with

The reading unit 3 reads the image of the document D. The reading unit 3 generates image data from the read image. The document transport section 4 transports the document D to the reading section 3 . The paper feed section 5 accommodates a plurality of sheets P. Paper feeding section 5 feeds paper P to transport section 6 . The paper P is made of paper or synthetic resin, for example. Paper P is an example of a recording medium. The conveyance unit 6 includes a plurality of conveyance roller pairs. The transport section 6 transports the paper P via the image forming section 2 to the discharge section 7 .

The image forming section 2 forms a toner image on paper P using an electrophotographic method based on the image data. The image data indicates an image of document D, for example. The image forming section 2 includes, for example, a photosensitive drum, a charging device, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a static eliminator.

The fixing device 1 heats and presses the toner image to fix the toner image on the paper P. The conveyance section 6 conveys the paper P on which the toner image is fixed to the discharge section 7 . The ejection unit 7 ejects the paper P to the outside of the casing of the image forming apparatus 100 .

Next, the details of the configuration of the fixing device 1 of this embodiment will be described with reference to FIGS. 2 to 4. FIG. 2 is a perspective view showing the main parts of the fixing device 1 according to the present embodiment.

As shown in FIG. 2, the fixing device 1 includes a fixing belt 10, a pressure member 20, a heating section 30, and a pair of belt holding sections 60.

The fixing belt 10 heats the paper P onto which the toner image has been transferred. The fixing belt 10 is endless. Fixing belt 10 has a substantially cylindrical shape. Fixing belt 10 has flexibility. The fixing belt 10 is rotatable about the first rotation axis L1. The first rotation axis L1 and the Y-axis are parallel. Fixing belt 10 extends along first rotation axis L1.

Define a first direction DY. The first direction DY indicates the direction DY in which the first rotation axis L1 extends. Hereinafter, the first direction DY may be referred to as "the width direction DY of the fixing belt 10." Hereinafter, the side in the first direction DY where the heating unit 30 is arranged may be referred to as "one end side in the first direction DY", and the opposite side may be referred to as "the other end side in the first direction DY".

Fixing belt 10 has multiple layers. The fixing belt 10 includes, for example, a polyimide layer and a release layer. The release layer is formed on the outer peripheral surface of the polyimide layer. The release layer is, for example, a heat-resistant film made of fluororesin.

Fixing belt 10 has a first end 101 and a second end 102. The first end portion 101 is an end portion of the fixing belt 10 on the other end side in the first direction DY. The second end portion 102 is an end portion of the fixing belt 10 on one end side in the first direction DY.

The pair of belt holding sections 60 rotatably hold the fixing belt 10. Specifically, the pair of belt holding parts 60 includes a first holding member 61 and a second holding member 62. The first holding member 61 is attached to the first end portion 101 of the fixing belt 10 . The second holding member 62 is attached to the second end portion 102 of the fixing belt 10 .

The pressure member 20, together with the fixing belt 10, presses the paper P onto which the toner image has been transferred. Specifically, the pressure member 20 has a substantially cylindrical shape and is arranged to face the fixing belt 10 . Pressure member 20 is pressed against fixing belt 10 . In other words, the pressure member 20 presses the fixing belt 10. The pressure member 20 is, for example, a pressure roller. The pressure member 20 extends along the first direction DY.

The pressure member 20 includes a core bar 21, an elastic layer 22, and a release layer 23. The core metal 21 has a cylindrical shape. The elastic layer 22 is formed on the core bar 21 . The elastic layer 22 has a cylindrical shape. The release layer 23 is formed to cover the surface of the elastic layer 22. The core metal 21 is rotatable about the second rotation axis L2. The second rotation axis L2 and the first rotation axis L1 are substantially parallel. The material of the core metal 21 is, for example, stainless steel or aluminum. The elastic layer 22 has elasticity. The material of the elastic layer 22 is, for example, silicone rubber. The material of the release layer 23 is, for example, fluororesin.

FIG. 3 is an exploded perspective view showing the fixing device 1 according to this embodiment. As shown in FIG. 3, the heating section 30 includes a heater 31, a heater holding member 32, a reinforcing member 33, a plurality of heat sensitive bodies 34, and a plurality of cover members 37.

The heater 31 heats the fixing belt 10. The heater 31 extends along the first direction DY. Specifically, the heater 31 has a heater surface 310. The heater surface 310 has a planar shape or an elongated thin plate shape. The heater 31 is, for example, a planar heater or an elongated thin plate heater. The heater 31 is, for example, a ceramic heater. A ceramic heater has a ceramic substrate and a resistance heating element. The thickness of the heater 31 is, for example, 1 mm.

A second direction DX and a third direction DZ are defined. The second direction DX indicates a direction perpendicular to the heater surface 310 of the heater 31. The second direction DX and the X-axis are parallel. In the second direction DX, the side on which the pressure member 20 is arranged may be referred to as "one end side of the second direction DX", and the opposite side may be referred to as "the other end side of the second direction DX". The third direction DZ indicates a direction perpendicular to the first direction DY and the second direction DX. The third direction DZ and the Z axis are parallel.

The heater holding member 32 holds the heater 31. The heater holding member 32 is made of, for example, heat-resistant resin. The heater holding member 32 extends along the first direction DY. Of the two ends of the heater holding member 32 in the first direction DY, the end closer to the second end 102 of the fixing belt 10 is directly connected to a connector disposed in the main body of the image forming apparatus 100, for example. Or they can be fitted indirectly.

The heater holding member 32 has a main body portion 321 and a plurality of protrusions 320. The plurality of protrusions 320 regulate the shape of the fixing belt 10 when the fixing device 1 is driven. Each of the plurality of protrusions 320 protrudes from the main body portion 321. Details of the heater holding member 32 will be described later with reference to FIGS. 6 to 8.

The plurality of heat sensitive bodies 34 sense the heat of the heater 31. The plurality of heat sensitive bodies 34 face the heater 31 . Each of the plurality of heat sensitive bodies 34 is arranged on the heater holding member 32. For example, the center portion of the heat sensitive body 34 is inserted into an opening formed in the heater holding member 32 and is adjacent to the heater 31 . The plurality of heat sensitive bodies 34 include a first heat sensitive body 34A and a second heat sensitive body 34B.

The heat sensitive body 34 includes a thermocut, a thermostat, or a thermistor. ThermoCut is a one-shot thermostat-like protection element. Thermocut cuts off the supply of power to the heater 31 when the temperature of the heater 31 is equal to or higher than a threshold value. In thermo-cut, once the power supply is cut off depending on the temperature of the heater 31, the power supply is not restored. The thermostat cuts off power supply to the heater 31 when the temperature of the heater 31 is equal to or higher than a threshold value. The thermostat restores power supply to the heater 31 when the temperature of the heater 31 is below a threshold value. The thermistor is a semiconductor element that measures the temperature of the heater 31. Image forming apparatus 100 controls heater 31 based on the temperature measured by the thermistor.

The plurality of cover members 37 face the heater holding member 32 with the heat sensitive body 34 in between. Specifically, the cover member 37 overlaps the heater 31, the heater holding member 32, and the heat sensitive body 34 in the second direction DX. The cover member 37 overlaps the heater 31, the heater holding member 32, and the heat sensitive element 34 in the second direction DX. The cover member 37 is, for example, a box-shaped member made of resin and has heat resistance. Each of the plurality of cover members 37 covers at least a portion of the corresponding heat sensitive body 34 . The plurality of cover members 37 include a first cover member 37A and a second cover member 37B. Specifically, the first cover member 37A covers at least a portion of the first heat sensitive body 34A. Further, the second cover member 37B covers at least a portion of the second heat sensitive body 34B.

A plurality of biasing members 35 are attached to the second cover member 37B. The biasing member 35 is, for example, a coil spring. The biasing member 35 has, for example, a cylindrical shape, a conical shape, or a barrel shape. The plurality of biasing members 35 are arranged along the first direction DY. Two biasing members 35 are attached to one second cover member 37B. The two biasing members 35 bias the second heat sensitive body 34B via the second cover member 37B.

The reinforcing member 33 reinforces the heater holding member 32. The reinforcing member 33 is, for example, an elongated metal stay member. The reinforcing member 33 has a substantially inverted U-shape when viewed in cross section from the direction along the first direction DY. The reinforcing member 33 extends along the first direction DY. The reinforcing member 33 is fixed opposite to the heater holding member 32.

FIG. 4 is a cross-sectional view taken along cutting line IV in FIG. 2. FIG. Note that, in order to facilitate understanding, a part of the interior of the fixing belt 10 is omitted in FIG. 4.

As shown in FIG. 4, the fixing belt 10 further includes an outer circumferential surface 103 and an inner circumferential surface 104. Further, the pressure member 20 has an outer circumferential surface 201. The outer circumferential surface 103 of the fixing belt 10 contacts the outer circumferential surface 201 of the pressure member 20 in a state where there is no paper P in the fixing nip region RN. Note that in FIG. 4, the outer circumferential surface 103 faces the outer circumferential surface 201 with the paper P interposed therebetween.

An inner circumferential surface 104 of the fixing belt 10 faces the heating section 30 . In other words, the heating unit 30 is arranged in a space inside the fixing belt 10. Specifically, the heater holding member 32 of the heating unit 30 is arranged on the inner circumferential surface 104 side of the fixing belt 10 . Heater holding member 32 faces fixing belt 10 with heater 31 interposed therebetween. The heater 31 receives pressure from the pressure member 20 via the fixing belt 10 . The heater 31 receives pressure from the reinforcing member 33 via the heater holding member 32.

The outer peripheral surface 103 of the fixing belt 10 and the outer peripheral surface 201 of the pressure member 20 contact each other to form a fixing nip region RN.

The pressure member 20 is rotatable about the second rotation axis L2. When the pressure member 20 rotates, the fixing belt 10 rotates following the pressure member 20. With these configurations, when the paper P passes through the fixing nip region RN, the toner image is fixed on the paper P. Note that the paper P is transported in the sheet transport direction T (positive side of the Z-axis).

Hereinafter, the upstream side in the sheet conveyance direction T may be referred to as "one end side in the third direction DZ", and the opposite side may be referred to as "the other end side in the third direction DZ".

Next, with reference to FIG. 5, the configuration of the pair of belt holding parts 60 will be further described. FIG. 5 is a perspective view of a pair of belt holding parts 60 according to this embodiment. Since the configurations of the first holding member 61 and the second holding member 62 are the same, the configuration of the first holding member 61 will be described, and the description of the configuration of the second holding member 62 will be omitted.

As shown in FIG. 5, the first holding member 61 includes a guide portion 611 and a regulating portion 612. The guide portion 611 is provided upright from the regulating portion 612 along the first direction DY. The regulating portion 612 regulates movement of the fixing belt 10 toward the other end in the width direction DY when the first end portion 101 of the fixing belt 10 is attached to the first holding member 61 . The regulating portion 612 has a flat plate shape.

Guide portion 611 supports fixing belt 10 . When the guide portion 611 is viewed from the first direction DY, the outer peripheral surface of the guide portion 611 has a substantially C-shape. The guide portion 611 has a shape that tapers from the regulating portion 612 toward one end side in the first direction DY. The guide portion 611 has a contact portion 611A, an inclined portion 611B, and a tip portion 611C. The contact portion 611A, the inclined portion 611B, and the tip portion 611C are formed in this order from the restriction portion 612 toward one end side in the first direction DY.

The contact portion 611A contacts the fixing belt 10. Specifically, the contact portion 611A contacts the inner circumferential surface 104 of the fixing belt 10 and rotatably holds the fixing belt 10. The inclined portion 611B and the tip portion 611C are unlikely to come into contact with the inner circumferential surface 104 of the fixing belt 10 when the fixing device 1 is in a stationary state and in a driven state.

Next, the configuration of the heating section 30 will be further explained with reference to FIGS. 6 to 8. FIG. 6 is a perspective view of the heater holding member 32 and the pair of belt holding parts 60. FIG. 7 is a top view of the heater holding member 32 and the pair of belt holding parts 60. FIG. 8 is an enlarged view of region R in FIG.

As shown in FIG. 6 , the heater holding member 32 includes a main body portion 321 and a plurality of protrusions 320 . The main body portion 321 has a first side wall portion 3211 on the other end side in the third direction DZ, a second side wall portion 3212 on the one end side in the third direction DZ, and a bottom wall portion 3213. The first side wall portion 3211 is erected from the end of the bottom wall portion 3213 on the other end side in the third direction DZ toward the other end side in the second direction DX. The second side wall portion 3212 is erected from the end of the bottom wall portion 3213 on the one end side in the third direction DZ toward the other end side in the second direction DX. Each of the first side wall portion 3211, the second side wall portion 3212, and the bottom wall portion 3213 is a plate-shaped member.

The plurality of protrusions 320 are arranged on the first side wall portion 3211. The plurality of protrusions 320 protrude from the first side wall portion 3211 toward the other end side in the third direction DZ. As shown in FIG. 6, the shape of the protrusion 320 is approximately triangular when viewed from the first direction DY.

The first side wall portion 3211 has a central portion PA, one end side portion PB, and the other end side portion PC. The other end side part PC, the center part PA, and the one end side part PB are continuously formed in this order from one end side of the first side wall part 3211 in the first direction DY to the other end side. One end side portion PB includes a first end portion PBA and a first intermediate portion PBB. The first end portion PBA includes an end portion of the first side wall portion 3211 and the second side wall portion 3212 of the main body portion 321 on the other end side in the first direction DY. The first intermediate portion PBB indicates a region of the main body portion 321 from the center portion PA to the first end portion PBA in the first side wall portion 3211 and the second side wall portion 3212 in the first direction DY. The other end side part PC includes a second end part PCA and a second intermediate part PCB. The second end portion PCA includes an end portion of the first side wall portion 3211 and the second side wall portion 3212 of the main body portion 321 on the one end side in the first direction DY. The second intermediate portion PCB indicates a region of the main body portion 321 from the center portion PA to the second end portion PCA in the first side wall portion 3211 and the second side wall portion 3212 in the first direction DY. The length of each of the center portion PA, the first end portion PBA, and the second end portion PCA in the first direction DY is adjusted according to the size of the paper P. For example, when the size of the paper P is A4, the entire length of the heater holding member 32 is approximately 240 mm in the first direction DY, and each of the central portion PA, first end portion PBA, and second end portion PCA is approximately 240 mm long. The length is about 20 mm.

The plurality of protrusions 320 are arranged in parallel from the first end PBA to the second end PCA of the first side wall portion 3211 in the first direction DY. The plurality of protrusions 320 include a plurality of first protrusions 320A and a plurality of second protrusions 320B. The plurality of first protrusions 320A are formed in the center portion PA of the first side wall portion 3211. The plurality of second protrusions 320B are formed in a portion of the first side wall portion 3211 that is different from the center portion PA of the first side wall portion 3211. In this embodiment, three first protrusions 320A are formed in the center PA of the first side wall 3211, and three second protrusions 320B are formed in the first end PBA and second end PCA. It is formed. The second protrusion 320B of the first end PBA and the second end PCA is an example of a third protrusion. The second protrusion 320B of the first intermediate portion PBB and the second intermediate portion PCB is an example of the fourth protrusion.

In the present embodiment, the plurality of protrusions 320 are densely formed at one end, the other end, and the center of the first side wall 3211 in the first direction DY. Other parts of 3211 are sparsely formed. In other words, in the central portion PA, the first end PBA, and the second end PCA, the distance between adjacent protrusions 320 is narrower than in other regions. Hereinafter, the interval between adjacent protrusions 320 will be referred to as "protrusion interval". Specifically, as shown in FIG. 7, the distance between each of the plurality of first protrusions 320A in the central portion PA, the first end PBA, and the second end PCA is the first distance d1. The remaining distance between the protrusions is the second distance d2. Specifically, the distance between each of the second protrusions 320B in the first intermediate portion PBB and the second intermediate portion PCB is the second interval d2. Furthermore, the protrusion interval between the second protrusion 320B of the first end portion PBA closest to one end in the first direction DY and the second protrusion 320B of the first intermediate portion PBB closest to the other end in the first direction DY. is the second interval d2. The distance between the second protrusion 320B of the first intermediate portion PBB closest to one end in the first direction DY and the first protrusion 320A of the center portion PA closest to the other end in the first direction DY is the second protrusion interval. The interval is d2. The distance between the first protrusion 320A of the central portion PA closest to one end in the first direction DY and the second protrusion 320B of the second intermediate portion PCB closest to the other end in the first direction DY is the second protrusion interval. The interval is d2. The distance between the second protrusion 320B of the second intermediate portion PCB closest to one end in the first direction DY and the second protrusion 320B of the second end PCA closest to the other end in the first direction DY is as follows: This is the second interval d2.

The first interval d1 is smaller than the second interval d2. For example, the first spacing d1 is half the second spacing d2. The second interval d2 is, for example, 7 mm to 10 mm.

As shown in FIG. 7, the plurality of protrusions 320 are arranged on the second side wall portion 3212. As shown in FIG. The plurality of protrusions 320 protrude from the second side wall portion 3212 in a direction opposite to the plurality of protrusions 320 on the first side wall portion 3211. The plurality of protrusions 320 are formed from the first end PBA to the second end PCA of the second side wall portion 3212 in the first direction DY. The distance between each of the plurality of protrusions 320 on the second side wall portion 3212 and the distance between each of the plurality of protrusions 320 on the first side wall portion 3211 are the same.

As shown in FIG. 8, the height h1 of the first protrusion 320A from the main body 321 is higher than the height h2 of the second protrusion 320B from the main body 321. Hereinafter, the height h1 of the first protrusion 320A from the main body 321 will be referred to as "the height h1 of the first protrusion 320A", and the height h2 of the second protrusion 320B from the main body 321 will be referred to as "the second protrusion 320A". "height h2 of protrusion 320B" may be written. The height h1 of the first protrusion 320A indicates the distance from the first side wall 3211 to the apex of the first protrusion 320A of the first side wall 3211 in the third direction DZ, Regarding the first protrusion 320A of the second side wall portion 3212, the distance from the second side wall portion 3212 to the apex of the first protrusion 320A is shown. The height h2 of the second protrusion 320B indicates the distance from the first side wall 3211 to the apex of the second protrusion 320B for the second protrusion 320B of the first side wall 3211 in the third direction DZ, Regarding the second protrusion 320B of the second side wall portion 3212, the distance from the second side wall portion 3212 to the apex of the second protrusion 320B is shown.

Next, the configuration of the fixing device 1 will be further described with reference to FIGS. 9(a) to 9(c). 9(a) is a sectional view taken along cutting line IXA in FIG. 7. FIG. Specifically, FIG. 9A is a cross-sectional view of the heater holding member 32 to which the pair of belt holding parts 60 are attached at a portion not having the protrusion 320 in the first direction DY. FIG. 9(b) is a cross-sectional view taken along cutting line IXB in FIG. Specifically, FIG. 9(b) is a cross-sectional view of the heater holding member 32 to which the pair of belt holding parts 60 are attached at a portion having the first protrusion 320A in the first direction DY. FIG. 9(c) is a cross-sectional view taken along cutting line IXC in FIG. Specifically, FIG. 9(c) is a cross-sectional view of the heater holding member 32 to which the pair of belt holding parts 60 are attached at a portion having the second protrusion 320B in the first direction DY.

As shown in FIG. 9(a), the contact portion 611A of the guide portion 611 of the first holding member 61 has a maximum width W1 in the third direction DZ. The maximum width W1 indicates the length of a straight line connecting the apex 611TA of the contact portion 611A on the other end side in the third direction DZ and the apex 611TB of the contact portion 611A on the one end side in the third direction DZ.

As shown in FIG. 9(b), the heater holding member 32 has a first maximum width W2 in the third direction DZ. The first maximum width W2 of the heater holding member 32 is defined by the apex 320AA of the first protrusion 320A protruding from the first side wall 3211 on the other end side in the third direction DZ and the first protrusion protruding from the second side wall 3212. It shows the length of a straight line connecting the apex 320AB of the strip 320A on one end side in the third direction DZ. That is, in the third direction DZ, the first maximum width W2 of the heater holding member 32 indicates the widest width at the central portion PA of the heater holding member 32.

In this embodiment, the first maximum width W2 of the heater holding member 32 is the same as the maximum width W1 of the contact portion 611A. That is, when viewed from the first direction DY, the apex 320AA on the other end side in the third direction DZ of the first protrusion 320A protruding from the first side wall part 3211 and the other end in the third direction DZ of the contact part 611A It overlaps with the side apex 611TA. Similarly, when viewed from the first direction DY, the apex 320AB of the first protrusion 320A protruding from the second side wall portion 3212 on one end side in the third direction DZ and the one end side of the contact portion 611A in the third direction DZ overlaps with the vertex 611TB. Therefore, when the pair of belt holding parts 60 are attached to the fixing belt 10, the first protrusions 320A easily come into contact with the inner circumferential surface 104 of the fixing belt 10 when the fixing device 1 is in a stationary state. Further, in the driving state of the fixing device 1, the first protrusion 320A easily comes into contact with the inner circumferential surface 104 of the fixing belt 10. In particular, the first protrusion 320A protruding from the second side wall portion 3212 on the upstream side in the sheet conveyance direction T contacts the inner circumferential surface 104 of the fixing belt 10 when the fixing device 1 is in the driving state.

As shown in FIG. 9(c), the heater holding member 32 has a second maximum width W3 in the third direction DZ. The second maximum width W3 of the heater holding member 32 is defined by the apex 320BA of the second protrusion 320B protruding from the first side wall 3211 on the other end side in the third direction DZ and the second protrusion protruding from the second side wall 3212. It shows the length of a straight line connecting the apex 320BB of the strip 320B on one end side in the third direction DZ. That is, in the third direction DZ, the second maximum width W3 of the heater holding member 32 indicates the widest width at the one end side portion PB and the other end side portion PC of the heater holding member 32.

In this embodiment, the second maximum width W3 of the heater holding member 32 is narrower than the maximum width W1 of the contact portion 611A. In other words, the second maximum width W3 of the heater holding member 32 is narrower than the first maximum width W2 of the heater holding member 32. That is, when viewed from the first direction DY, the apex 320BA of the second protrusion 320B protruding from the first side wall portion 3211 on the other end side in the third direction DZ is the other end of the contact portion 611A in the third direction DZ. It is located closer to one end in the third direction DZ than the side apex 611TA. Similarly, when viewed from the first direction DY, the apex 320BB on one end side in the third direction DZ of the second protrusion 320B protruding from the second side wall portion 3212 and the apex 320BB on the one end side in the third direction DZ of the contact portion 611A It is located on the other end side in the third direction DZ than the vertex 611TB. Therefore, when the pair of belt holding parts 60 are attached to the fixing belt 10, the second protrusions 320B are unlikely to come into contact with the inner circumferential surface 104 of the fixing belt 10 when the fixing device 1 is in a stationary state and in a driven state.

Thus, in the present embodiment, the maximum width W1 of the contact portion 611A is the same as the first maximum width W2 of the heater holding member 32 in the third direction DZ. Furthermore, the first maximum width W2 of the heater holding member 32 is wider than the second maximum width W3 of the heater holding member 32.

Next, the configuration of the fixing device 1 will be further described with reference to FIGS. 10(a) to 11(b). FIG. 10(a) is a partial cross-sectional view taken along cutting line XA in FIG. FIG. 10B is a partial sectional view of the protrusion 320 of this embodiment and the fixing belt 10 at the center PA of the heater holding member 32 in the Y-axis direction when the fixing device 1 is in a stationary state. FIG. 11A is a partial cross-sectional view of the protrusion 320 of this embodiment and the fixing belt 10 at the center PA of the heater holding member 32 in the Y-axis direction when the fixing device 1 is in a driving state. FIG. 11B is a partial cross-sectional view of the protrusion 320 of the comparative example and the fixing belt 10 at the central portion PA of the heater holding member 32 in the Y-axis direction in a driving state of the fixing device of the comparative example. The fixing device of the comparative example has a configuration in which a second protrusion 320B is formed in the central portion PA of the heater holding member 32 instead of the first protrusion 320A, and the spacing between the protrusions in the central portion PA of the heater holding member 32 is The configuration is the same as that of the fixing device 1 of this embodiment except for the second interval d2.

As shown in FIG. 10A, when the fixing device 1 is in a stationary state, the inner circumferential surface 104 of the fixing belt 10 has a contact portion 611A of the first holding member 61 and a contact portion 611A of the second holding member 62. are in contact. In this embodiment, when the fixing device 1 is in a stationary state, the inner circumferential surface 104 of the fixing belt 10 and the first protrusion 320A are likely to come into contact with each other. On the other hand, when the fixing device 1 is in a stationary state, the inner circumferential surface 104 of the fixing belt 10 and the second protrusion 320B are unlikely to come into contact with each other. That is, as shown in FIG. 10(b), in the third direction DZ, the height h1 of the plurality of first protrusions 320A is approximately the same as the height h3 of the contact portion 611A from the main body portion 321. Moreover, the height h2 of the plurality of second protrusions 320B is lower than the height h1 of the plurality of first protrusions 320A. The height h2 of the contact portion 611A from the main body portion 321 indicates the distance from the first side wall portion 3211 or the second side wall portion 3212 to the contact portion 611A in the Z direction, as shown in FIG. 10(a).

In the driving state of the fixing device 1 of this embodiment, the center portion of the fixing belt 10 in the width direction DY may be recessed. In particular, the center portion of the fixing belt 10 in the width direction DY on the upstream side in the sheet conveyance direction T is likely to be dented. As shown in FIG. 11A, when the center portion of the fixing belt 10 in the width direction DY is recessed in the driving state of the fixing device 1 of the present embodiment, the inner circumferential surface 104 of the center portion of the fixing belt 10 is It contacts the three first protrusions 320A of the central portion PA. In other words, the three first protrusions 320A of the central portion PA try to restrict the deformation of the shape of the fixing belt 10. At this time, the maximum recess depth of the fixing belt 10 is a relatively small first depth F1.

On the other hand, as shown in FIG. 11B, when the center portion of the fixing belt 10 in the width direction DY is recessed in the driving state of the fixing device of the comparative example, the inner circumferential surface 104 of the center portion of the fixing belt 10 is It contacts the two second protrusions 320B of the central portion PA. At this time, the maximum recess depth of the fixing belt 10 is a relatively large second depth F2. In the fixing device of the comparative example, the height h2 of the second protrusion 320B in the central portion PA is lower than the height h1 of the first protrusion 320A. Furthermore, the second spacing d2 of each of the second protrusions 320B in the central portion PA is wider than the first spacing d1. Therefore, in the fixing device of the comparative example, the center portion of the fixing belt 10 in the width direction DY is recessed more deeply than in the fixing device 1 of the present embodiment. That is, the second depth F2 is greater than the first depth F1. As a result, in the fixing device of the comparative example, cracks are more likely to occur in the fixing belt 10 than in the fixing device 1 of the present embodiment.

Next, the configuration of the heating section 30 of this embodiment will be further described with reference to FIGS. 12(a) and 12(b). FIG. 12A is an enlarged view of the second end PCA side of the heater holding member 32 viewed from the Z-axis positive side. FIG. 12(b) is a diagram of the second end PCA side of the heater holding member 32 viewed from the negative side of the X-axis.

As shown in FIGS. 12(a) and 12(b), the plurality of second protrusions 320B are arranged on the first side wall portion 3211 and the second side wall portion 3212. Specifically, as described with reference to FIG. 7, at the second end PCA, adjacent second protrusions 320B are arranged with a first interval d1 in the first direction DY. In the second intermediate portion PCB, adjacent second protrusions 320B are arranged with a second interval d2 in the first direction DY. Also, a second protrusion 320B located closest to the other end side in the first direction DY of the second end portion PCA, and a second protrusion 320B located closest to one end side in the first direction DY of the second intermediate portion PCB. are arranged at a second interval d2.

The fixing belt 10 and heating unit 30 of this embodiment will be described with reference to FIGS. 13(a) and 13(b). FIG. 13A is a cross-sectional view showing a state in which the fixing belt 10 is inserted into the heater holding member 32 from the second end PCA side of the heater holding member 32. FIG. FIG. 13(b) is a cross-sectional view showing a state in which the fixing belt 10 is inserted into the heater holding member 32. Note that FIGS. 13(a) and 13(b) show a cross section of the fixing belt 10 along the width direction DY when viewed from the negative side of the X-axis.

The operator moves the heating unit 30 along the width direction DY of the fixing belt 10. Thereby, the heating unit 30 can be placed within the inner circumferential surface 104 of the fixing belt 10 . Note that the fixing belt 10 is thin and easily broken. Therefore, the machine cannot insert the heating section 30 into the inner circumferential surface 104 of the fixing belt 10.

Specifically, the heating section 30 is inserted into the fixing belt 10 as follows. First, an operator presses a portion of the fixing belt 10 a predetermined distance away from the first end 101 with a finger. When the fixing belt 10 is pressed, the first end 101 of the fixing belt 10 is deformed. Specifically, when the first end 101 of the fixing belt 10 is pressed in the second direction DX, the first end 101 of the fixing belt 10 deforms into an elongated oval shape in the third direction DZ. When the first end 101 of the fixing belt 10 is expanded, it becomes easier to insert the heating unit 30 from the first end 101 of the fixing belt 10 .

Next, the operator inserts the heating unit 30 from the first end 101 of the fixing belt 10 . As shown in FIG. 13A, when the heating section 30 is inserted into the fixing belt 10, the second protrusion 320B of the second end PCA comes into contact with the inner peripheral surface 104 of the fixing belt 10. At this time, in this embodiment, since the rib interval of the second protruding rim 320B of the second end PCA is the first interval d1, the rib interval of the second protruding rim 320B of the second end PCA is the second interval d2. The first end 101 of the fixing belt 10 is less likely to be caught by the second protrusion 320B of the second end PCA than in the case of Therefore, the operator can easily insert the heating section 30 into the fixing belt 10. As shown in FIG. 13(b), once the first end 101 of the fixing belt 10 is inserted into the heating section 30, the operator can stably insert the remaining part of the heating section 30 into the fixing belt 10. .

As described with reference to FIGS. 1 to 13, the fixing device 1 includes the fixing belt 10, the heating section 30, and a pair of belt holding sections 60. The heating section 30 includes a heater 31 and a heater holding member 32. The heater holding member 32 has a main body portion 321 and a plurality of protrusions 320. The plurality of protrusions 320 include a plurality of first protrusions 320A and a plurality of second protrusions 320B. In the third direction DZ, the maximum width W1 of the contact portion 611A is the same as the first maximum width W2 of the heater holding member 32. The first maximum width W2 of the heater holding member 32 is wider than the second maximum width W3 of the heater holding member 32. As a result, in the fixing device 1, when the fixing device 1 is driven, the center portion of the fixing belt 10 in the width direction DY is When the fixing belt 10 is recessed, the inner circumferential surface 104 of the fixing belt 10 is more likely to come into contact with the protrusion 320 of the central portion PA. Thereby, the fixing device 1 can further reduce the size of the recess at the center of the fixing belt 10 in the width direction DY. As a result, the fixing device 1 can further suppress the occurrence of cracks in the fixing belt 10.

As described with reference to FIGS. 1 to 13, the plurality of second protrusions 320B include the plurality of second protrusions 320B at the first end PBA and the second end PCA, the first intermediate part PBB, and the plurality of second protrusions 320B at the first end PBA and the second end PCA. and a plurality of second protrusions 320B of the second intermediate portion PCB. The plurality of second protrusions 320B of the first end PBA and the second end PCA are arranged at a first interval d1. The plurality of second protrusions 320B of the first intermediate portion PBB and the second intermediate portion PCB are arranged at a second interval d2. The first interval d1 is smaller than the second interval d2. As a result, in the fixing device 1, the heating unit 30 is heated inside the fixing belt 10 more than in the case where the interval between the plurality of second protrusions 320B at the first end PBA and the second end PCA is the second interval d2. , the first end 101 or the second end 102 of the fixing belt 10 is unlikely to be caught by the second protrusion 320B of the first end PBA or the second end PCA. As a result, the fixing device 1 allows the operator to easily insert the heating unit 30 into the fixing belt 10 from either the first end 101 or the second end 102 of the fixing belt 10 .

The embodiments of the present invention have been described above with reference to FIGS. 1 to 13. However, the present invention is not limited to the above-described embodiments, and can be implemented in various embodiments without departing from the spirit thereof (for example, (1) to (5) shown below). The drawings mainly show each component schematically to make it easier to understand, and the thickness, length, number, etc. of each component shown in the diagram may differ from the actual one due to the drawing process. . Further, the materials, shapes, dimensions, etc. of each component shown in the above embodiments are merely examples, and are not particularly limited, and various changes can be made without substantially departing from the effects of the present invention. be.

(1) As described with reference to FIGS. 1 to 13, in the embodiment of the present invention, the image forming apparatus 100 is a monochrome multifunction peripheral, but the present invention is not limited to this. For example, image forming apparatus 100 may be a monochrome printer. Alternatively, the image forming apparatus 100 may be a color multifunction device or a monochrome multifunction device.

(2) As described with reference to FIGS. 1 to 13, in the embodiment of the present invention, the maximum width W1 of the contact portion 611A is equal to the first maximum width W2 of the heater holding member 32 in the third direction DZ. Although they are the same, the present invention is not limited thereto. For example, in the third direction DZ, the maximum width W1 of the contact portion 611A is wider than the first maximum width W2 of the heater holding member 32, and the first maximum width W2 of the heater holding member 32 is wider than the first maximum width W2 of the heater holding member 32. 2 may be wider than the maximum width W3. In this case, the driving of the fixing device 1 is faster than when the maximum width W1 is wider than the first maximum width W2 of the heater holding member 32 and the first maximum width W2 is narrower than the second maximum width W3 of the heater holding member 32. Sometimes, when the center portion of the fixing belt 10 in the width direction DY is recessed, the inner circumferential surface 104 of the fixing belt 10 comes into contact more easily than the protrusion 320 of the center portion PA. Thereby, the fixing device 1 can further reduce the size of the recess at the center of the fixing belt 10 in the width direction DY. As a result, the fixing device 1 can further suppress the occurrence of cracks in the fixing belt 10.

(3) As described with reference to FIGS. 1 to 13, in the embodiment of the present invention, the first maximum width W2 of the heater holding member 32 is the second maximum width W2 of the heater holding member 32 in the third direction DZ. Although it is wider than W3, the present invention is not limited thereto. For example, the first maximum width W2 of the heater holding member 32 may be the same as the second maximum width W3 of the heater holding member 32. In this case, the generation of dents in the fixing belt 10 is more reliably suppressed when the fixing device 1 is driven than when the first maximum width W2 of the heater holding member 32 is wider than the second maximum width W3 of the heater holding member 32. can do. As a result, the fixing belt 10 is less prone to cracking even when used for a long period of time. As a result, the fixing device 1 can drive the fixing belt 10 more stably.

(4) As described with reference to FIGS. 1 to 13, in the embodiment of the present invention, the intervals between the plurality of protrusions 320 in the central portion PA, first end PBA, and second end PCA are , the first interval d1, but the present invention is not limited thereto. For example, the interval between the plurality of protrusions 320 in the central portion PA, the first end PBA, and the second end PCA may be the second interval d2. Moreover, the protrusion intervals of the plurality of protrusions 320 only in the central portion PA may be the first interval d1, and the protrusion intervals of the remaining plurality of protrusions 320 may be the second interval d2 or more.

(5) As described with reference to FIGS. 1 to 13, in the embodiment of the present invention, the central part PA, the first end part PBA, and the second end part of the first side wall part 3211 and the second side wall part 3212 Although three protrusions 320 are formed on each PCA, the present invention is not limited thereto. For example, the number of protrusions 320 disposed in the central portion PA of the first side wall portion 3211 and the second side wall portion 3212 may be one or two, or four or more. Further, the number of protrusions 320 disposed on each of the first end PBA and second end PCA of the first side wall 3211 and the second side wall 3212 may be two or four or more. It's okay.

INDUSTRIAL APPLICABILITY The present invention can be used in the field of image forming apparatuses.

1 fixing device 10 fixing belt;
104 Inner peripheral surface 30 Heating part 31 Heater 32 Heater holding member 321 Main body part 320 Projection 320A First projection 320B Second projection 60 Belt holding part 611A Contact part W1 Maximum width of contact part W2 First end of heater holding member Large W3 Second maximum width of heater holding member

Claims (4)

An endless fixing belt,
a heating section facing the inner circumferential surface of the fixing belt;
and a belt holding part that rotatably holds both ends of the fixing belt,
The heating section is
a heater that heats the fixing belt;
a heater holding member that holds the heater;
The heater holding member is
The main body and
a plurality of protrusions regulating the shape of the fixing belt;
Each of the plurality of protrusions protrudes from the main body,
The plurality of protrusions are
a plurality of first protrusions disposed in a central portion of the main body in a first direction where both ends of the fixing belt face each other;
a plurality of second protrusions arranged in a position different from the center part of the main body part;
The belt holding section has a contact section that contacts the inner circumferential surface of the fixing belt,
The plurality of second protrusions are:
a plurality of third protrusions arranged at at least one end in the width direction of the fixing belt in the main body;
The main body portion includes a plurality of fourth protrusions different from the plurality of third protrusions,
The plurality of third protrusions are arranged at a first interval,
The plurality of fourth protrusions are arranged at second intervals,
the first interval is smaller than the second interval,
(a) In a second direction perpendicular to the first direction and parallel to the heater surface of the heater, the maximum width of the contact portion is such that the plurality of first protrusions are arranged in the central portion of the heater holding member. and the first maximum width is the same as the first maximum width indicating the maximum width of the area where the plurality of second protrusions are arranged, and the first maximum width is the same as the first maximum width indicating the maximum width of the area where the plurality of second protrusions are arranged. (b) in the second direction, the maximum width of the contact portion is wider than the first maximum width, and the first maximum width is wider than the second maximum width; Fusing device. The plurality of second protrusions are:
the plurality of third protrusions arranged at both ends of the fixing belt in the width direction of the main body;
The fixing device according to claim 1 , wherein the main body portion includes a plurality of fourth protrusions different from the plurality of third protrusions. The fixing device according to claim 1 or 2 , wherein the heater is a planar heater. The fixing device according to any one of claims 1 to 3 ,
an image forming section that forms a toner image on a recording medium;
The fixing device is an image forming apparatus that fixes the toner image on the recording medium.

Images