JP2024130192A - Fixing device and image forming apparatus - Google Patents

Abstract

[Problem] To provide a fixing device capable of stabilizing a housing frame without increasing the weight or cost of the device. [Solution] A fixing device 9 that can be installed in an image forming device includes a housing frame, a rotatable endless fixing belt 20, a heater 22 for heating the fixing belt 20, a heater holder 23, a stay 24 disposed inside the fixing belt 20 and supporting the heater holder 23, a pressure roller 21 forming a nip portion N with the fixing belt 20, a guide plate member 26 for guiding a recording medium P to the nip portion N, and a separation plate member 25 for separating the recording medium P that has passed through the nip portion N from the fixing belt 20. The housing frame has a support plate member 29 disposed on the pressure roller 21 side, and a pair of side plate members 28 disposed on both ends of the support plate member 29 in the longitudinal direction, and the pair of side plate members 28 are held by at least one of the separation plate member 25, the guide plate member 26, and the stay 24 on the fixing belt 20 side. [Selected Figure] Figure 5

Description

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

In image forming devices such as copiers, printers, and facsimiles, images are formed by image forming processes such as electrophotographic recording, electrostatic recording, and magnetic recording, and an unfixed toner image is formed on a recording medium (such as paper) by an image transfer method or a direct method. As a fixing device for fixing an unfixed toner image, a fixing device equipped with a heating means is known that heats and pressurizes the toner image formed on the recording medium in the nip between the fixing member and the pressure roller to perform the fixing process.

From the viewpoint of energy saving, a thin belt member (fixing belt) with low thermal capacity is used as the fixing member in the fixing device used in an electrophotographic image forming apparatus. For example, a configuration is known in which a nip is formed between a heating element arranged on the inner surface of the fixing belt and a pressure roller via the fixing belt.

In a fixing device, stability of the housing frame and positional accuracy of the components are required. However, in a fixing device equipped with a heating unit, the positioning accuracy between the components may decrease due to differences in the thermal expansion coefficients of the components.
In response to this, Patent Document 1 discloses a configuration that includes a first positioning portion that positions the heating member and the holding member in the longitudinal direction of the heating member, a second positioning portion that positions the holding member and the device frame in the longitudinal direction of the heating member, and a third positioning portion that positions the device frame and the image forming device main body in the longitudinal direction of the heating member, and the first positioning portion and the second positioning portion, or the first positioning portion and the third positioning portion, are provided on the same side based on the center of the heat generating portion in the longitudinal direction of the heating member.

According to the configuration of JP-A-2003-133999, in a fixing device including a heating device, it is possible to improve the relative positional accuracy of the heating member, the holding member, and the housing frame.
However, since the housing frame of the fixing device has a first frame consisting of a pair of side walls and a front wall, and a second frame consisting of a rear wall, there are issues such as an increase in the size of the device, an increase in the weight of the device, and an increase in parts costs.
On the other hand, in order to stably hold the components arranged inside the device, it is essential to stabilize the housing frame.

The present invention aims to provide a fixing device that can stabilize the housing frame without increasing the weight or cost of the device.

In order to solve the above problem, the fixing device of the present invention is a fixing device that can be attached to an image forming device, and includes a housing frame, a rotatable endless fixing belt, a heater that heats the fixing belt, a heater holder that holds the heater, a stay that is arranged inside the fixing belt and supports the heater holder, a pressure roller that forms a nip with the fixing belt, a guide plate member that guides a recording medium to the nip, and a separation plate member that separates the recording medium that has passed through the nip from the fixing belt, and the housing frame has a support plate member that is arranged on the pressure roller side, and a pair of side plate members that are arranged on both ends of the support plate member in the longitudinal direction, and the pair of side plate members are held on the fixing belt side by at least one of the separation plate member, the guide plate member, and the stay.

The present invention provides a fixing device that can stabilize the housing frame without increasing the weight or cost of the device.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic configuration diagram of a fixing device according to the present embodiment. FIG. FIG. FIG. 2 is a side view of the fixing device according to the embodiment. 1A is a perspective view of the fixing device according to the present embodiment, FIG. 1B is a schematic plan view thereof, and FIG. 1C is a schematic plan view of a conventional fixing device. 11 is an explanatory diagram showing an example of a mode in which a side plate member is positioned and fixed by a separation plate member. FIG. 11 is an explanatory diagram showing an example of a mode in which a side plate member is positioned and fixed by a separation plate member; FIG. 11 is an explanatory diagram showing an example of a mode in which a side plate member is positioned and fixed by a separation plate member. FIG. 11 is an explanatory diagram showing an example of a mode in which a side plate member is positioned and fixed by a separation plate member. FIG. 11 is an explanatory diagram showing an example of a mode in which a side plate member is positioned and fixed by a separation plate member; FIG. 2 is a perspective view showing the fixing device and a fixing device installation frame of the image forming apparatus according to the embodiment; FIG. 1A is a perspective view showing a state in which the fixing device according to the present embodiment is mounted on an image forming apparatus, FIG. 1B is a schematic plan view, and FIG. 1C is a schematic plan view of a conventional fixing device. 1 is a partial perspective view of a fixing device according to an embodiment of the present invention when mounted on an image forming apparatus; FIG. 4 is a diagram illustrating dimensions of a side plate member. 13 is a diagram illustrating the dimensions of an insertion hole in a wall portion of the installation frame. FIG. 13 is a partial perspective view of a protruding end of a side plate member and an insertion hole in a wall portion of the installation frame. FIG. 1A is a diagram of a wall portion of an installation frame, and FIG. 1B is a diagram showing a state in which the fixing device according to the present embodiment is fixed. 1A is a diagram of a wall portion of an installation frame, and FIG. 1B is a diagram showing a state in which the fixing device according to the present embodiment is fixed. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. FIG. 21 is a plan view of the heater shown in FIG. 20. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. FIG. 1 is a diagram showing a configuration of an image forming apparatus different from that of the above embodiment. FIG. 27 is a diagram showing a configuration of the fixing device shown in FIG. 26 . FIG. 28 is a plan view of the heater shown in FIG. 27. FIG. 28 is a perspective view of the heater and heater holder shown in FIG. 27. FIG. 4 is a perspective view showing a state in which a connector is attached to a heater. 30A is a diagram showing the arrangement of a temperature sensor and a thermostat provided in the fixing device shown in FIG. 27, and FIG. 30B is a diagram showing a groove portion of the flange member shown in FIG. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. 33 is a perspective view of the heater, the first high thermal conductive member, and the heater holder shown in FIG. 32. FIG. 4 is a plan view of the heater showing the arrangement of the first high thermal conductive member. 13 is a plan view of the heater showing another example of the arrangement of the first high thermal conductivity member. FIG. 13 is a plan view of a heater showing still another example of the arrangement of the first high thermal conductivity member. FIG. FIG. 4 is a plan view of the heater showing enlarged divided regions. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. 39 is a perspective view of the heater, the first high thermal conductive member, the second high thermal conductive member, and the heater holder shown in FIG. 38. 4 is a plan view of the heater showing the arrangement of the first high thermal conductivity member and the second high thermal conductivity member. FIG. 10 is a plan view of a heater showing another example of the arrangement of the first high thermal conductivity member and the second high thermal conductivity member. FIG. 13 is a plan view of a heater showing still another example of the arrangement of the second high thermal conductive member. FIG. FIG. 4 is a diagram showing a configuration of a fixing device different from that of the above embodiment. FIG. 1 illustrates the atomic crystal structure of graphene. FIG. 1 illustrates the atomic crystal structure of graphite.

The fixing device and image forming apparatus according to the present invention will be described below with reference to the drawings. Note that the present invention is not limited to the following embodiment, and can be modified, added, modified, deleted, or otherwise changed within the scope of what a person skilled in the art can imagine. Any embodiment is within the scope of the present invention as long as it achieves the functions and effects of the present invention.
In addition, in each drawing, components such as members and components having the same function or shape are denoted by the same reference numerals as far as they can be distinguished, and the description thereof will be omitted after it has been described once.

FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention.
In this specification, the term "image forming apparatus" includes a printer, a copier, a facsimile, a printing machine, or a multifunction machine that combines two or more of these. Furthermore, in the following description, "image formation" refers not only to forming meaningful images such as characters and figures, but also to forming meaningless images such as patterns.
First, the overall configuration and operation of an image forming apparatus according to this embodiment will be described with reference to FIG.

The image forming device 100 shown in FIG. 1 has four imaging units 1Y, 1M, 1C, and 1Bk that are detachable from the image forming device main body. Each imaging unit 1Y, 1M, 1C, and 1Bk has the same configuration except that it contains a developer of a different color, yellow, magenta, cyan, or black. These color developers correspond to the color separation components of a color image. Each imaging unit 1Y, 1M, 1C, and 1Bk has a drum-shaped photoconductor 2 as an image carrier, a charging device 3, a developing device 4, and a cleaning device 5. The charging device 3 charges the surface of the photoconductor 2. The developing device 4 supplies toner as a developer to the surface of the photoconductor 2 to form a toner image. The cleaning device 5 cleans the surface of the photoconductor 2.

The image forming apparatus 100 also includes an exposure device 6 , a paper feed device 7 , a transfer device 8 , a fixing device 9 as a heating device, and a paper discharge device 10 .
The exposure device 6 exposes the surface of each photoconductor 2 to light, forming an electrostatic latent image on that surface. The paper feed device 7 supplies recording medium (hereinafter also referred to as "paper") P to a paper transport path 14. The transfer device 8 transfers the toner image formed on each photoconductor 2 to the paper P. The fixing device 9 fixes the toner image transferred to the paper P to the surface of the paper P. The paper discharge device 10 discharges the paper P outside the apparatus. The imaging units 1, the photoconductors 2, the charging device 3, the exposure device 6, the transfer device 8, etc. constitute an image forming means for forming an image on paper.

The image forming apparatus 100 also includes a fixing device installation frame 105 on which the fixing device 9 is detachably mounted.
The fixing device installation frame 105 has a structure for positioning the mounted fixing device 9. A specific aspect of the positioning will be described later.

The transfer device 8 has an endless intermediate transfer belt 11 as an intermediate transfer body, four primary transfer rollers 12 as primary transfer members, and a secondary transfer roller 13 as a secondary transfer member. The intermediate transfer belt 11 is stretched by a plurality of rollers. The primary transfer rollers 12 transfer the toner images on the photoconductors 2 to the intermediate transfer belt 11. The secondary transfer rollers 13 transfer the toner images transferred onto the intermediate transfer belt 11 to the paper P. Each of the multiple primary transfer rollers 12 contacts the photoconductors 2 via the intermediate transfer belt 11. As a result, the intermediate transfer belt 11 and each photoconductor 2 come into contact with each other, and a primary transfer nip is formed between them. Meanwhile, the secondary transfer roller 13 contacts one of the rollers that stretch the intermediate transfer belt 11 via the intermediate transfer belt 11. As a result, a secondary transfer nip is formed between the secondary transfer roller 13 and the intermediate transfer belt 11.

A pair of timing rollers 15 is provided on the paper transport path 14 between the paper feeder 7 and the secondary transfer nip (secondary transfer roller 13).

Next, the printing operation of the image forming apparatus will be described with reference to FIG.
When an instruction to start a printing operation is given, in each of the imaging units 1Y, 1M, 1C, and 1Bk, the photoconductor 2 is rotated clockwise in FIG. 1, and the surface of the photoconductor 2 is charged to a uniform high potential by the charging device 3. Next, the exposure device 6 exposes the surface of each photoconductor 2 based on the image information of the original read by the original reading device or the print information instructed to be printed from the terminal. This reduces the potential of the exposed portion, forming an electrostatic latent image. Toner is then supplied from the developing device 4 to this electrostatic latent image, and a toner image is formed on each photoconductor 2.

The toner images formed on each photoconductor 2 rotate with the rotation of each photoconductor 2 and reach the primary transfer nip (the position of the primary transfer roller 12). The toner images are then transferred to the intermediate transfer belt 11, which rotates counterclockwise in FIG. 1, so that they overlap one another. The toner images transferred onto the intermediate transfer belt 11 are then transported to the secondary transfer nip (the position of the secondary transfer roller 13) with the rotation of the intermediate transfer belt 11. The toner images are transferred to the paper P that has been transported at the secondary transfer nip. This paper P is supplied from the paper supply device 7. The paper P supplied from the paper supply device 7 is stopped once by the timing roller 15, and then transported to the secondary transfer nip in accordance with the timing at which the toner image on the intermediate transfer belt 11 reaches the secondary transfer nip. Thus, a full-color toner image is carried on the paper P. After the toner image is transferred, the toner remaining on each photoconductor 2 is removed by each cleaning device 5.

The paper P with the transferred toner image is transported to the fixing device 9, which fixes the toner image onto the paper P. The paper P is then discharged from the device by the paper discharge device 10, completing the printing process.

The recording media on which the image is formed include paper P (plain paper), as well as cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, overhead projector sheets, plastic film, prepreg, copper foil, etc.

Next, an example of the configuration of a fixing device to which the present invention is applied will be described.
As shown in FIG. 2, the fixing device 9 according to this embodiment is a fixing device 9 that can be attached to the image forming apparatus 100, and includes a housing frame, a rotatable endless fixing belt 20 as a fixing member, a heater 22 for heating the fixing belt 20, a heater holder 23 for holding the heater 22, a stay 24 arranged inside the fixing belt 20 and supporting the heater holder 23, a pressure roller 21 that forms a nip portion N with the fixing belt 20, a guide plate member 26 that guides a recording medium (paper P) to the nip portion N, and a separation plate member 25 that separates the recording medium (paper P) that has passed through the nip portion N from the fixing belt 20.

The heating device 19 is composed of a planar heater 22 as a heating member, a heater holder 23 as a holding member for holding the heater 22, and a stay 24 as a reinforcing member for reinforcing the heater holder 23 in the longitudinal direction.

2 is the longitudinal direction of the fixing belt 20, pressure roller 21, heater 22, heater holder 23, stay 24, separation plate member 25, guide plate member 26, etc., and hereinafter, this direction will be simply referred to as the longitudinal direction. Note that this longitudinal direction is also the width direction of the paper P being transported, the belt width direction of the fixing belt 20, and the axial direction of the pressure roller 21.

The fixing belt 20 has a cylindrical substrate made of polyimide (PI) with an outer diameter of 25 mm and a thickness of 40 to 120 μm. A release layer made of fluororesin such as PFA or PTFE with a thickness of 5 to 50 μm is formed on the outermost surface of the fixing belt 20 to enhance durability and ensure releasability. An elastic layer made of rubber or the like with a thickness of 50 to 500 μm may be provided between the substrate and the release layer. The substrate of the fixing belt 20 is not limited to polyimide, and may be a heat-resistant resin such as PEEK or a metal substrate such as nickel (Ni) or SUS. The inner peripheral surface of the fixing belt 20 may be coated with polyimide, PTFE, or the like as a sliding layer.

The pressure roller 21 has an outer diameter of, for example, 25 mm and is composed of a solid iron core 21a, an elastic layer 21b formed on the surface of the core 21a, and a release layer 21c formed on the outside of the elastic layer 21b. The elastic layer 21b is made of silicone rubber and has a thickness of, for example, 3.5 mm. To improve the release properties of the surface of the elastic layer 21b, it is desirable to form a release layer 21c made of a fluororesin layer having a thickness of, for example, about 40 μm.

The pressure roller 21 is urged toward the fixing belt 20 by the urging means, so that the pressure roller 21 is pressed against the heater 22 via the fixing belt 20. This forms a nip N between the fixing belt 20 and the pressure roller 21. The pressure roller 21 is also configured to be driven to rotate by the drive means, and when the pressure roller 21 rotates in the direction of the arrow in FIG. 2, the fixing belt 20 is rotated accordingly.

The heater 22 is provided longitudinally across the width of the fixing belt 20 and is arranged so as to contact the inner peripheral surface of the fixing belt 20. The heater 22 may be in non-contact with the fixing belt 20 or indirect contact via a low-friction sheet or the like, but the direct contact of the heater 22 with the fixing belt 20 improves the efficiency of heat transfer to the fixing belt 20. The heater 22 can also be in contact with the outer peripheral surface of the fixing belt 20, but since there is a risk that the fixing quality will decrease if the outer peripheral surface of the fixing belt 20 is damaged by contact with the heater 22, it is preferable that the heater 22 be in contact with the inner peripheral surface of the fixing belt 20.

The heater holder 23 and the stay 24 are disposed on the inner periphery of the fixing belt 20. The stay 24 is made of a metal channel material, and both ends are supported by both side walls of the fixing device 9. The stay 24 supports the surface of the heater holder 23 opposite the heater 22 side, so that the heater 22 and the heater holder 23 are maintained without being significantly deflected by the pressure force of the pressure roller 21, and a nip portion N is formed between the fixing belt 20 and the pressure roller 21.

The heater holder 23 is desirably made of a heat-resistant material because it is prone to becoming hot due to the heat of the heater 22. For example, if the heater holder 23 is made of a heat-resistant resin with low thermal conductivity such as LCP or PEEK, the heat transfer from the heater 22 to the heater holder 23 is suppressed, making it possible to heat the fixing belt 20 efficiently.

When the printing operation is started, the pressure roller 21 is driven to rotate, and the fixing belt 20 starts to rotate. In addition, the fixing belt 20 is heated by supplying power to the heater 22. Then, as shown in FIG. 2, when the temperature of the fixing belt 20 reaches a predetermined target temperature (fixing temperature), the paper P carrying the unfixed toner image is guided by the guide plate member 26 and transported between the fixing belt 20 and the pressure roller 21 (nip portion N), and the unfixed toner image is heated and pressurized to be fixed to the paper P. The fixed paper P is separated from the fixing belt 20 and the pressure roller 21 by the separation plate member 25.

The heating device provided in the fixing device according to this embodiment is shown in FIG. 3 and FIG.
FIG. 3 is a perspective view of the heating device 19, and FIG.
3, a rectangular accommodation recess 23a for accommodating the heater 22 is provided on the surface of the heater holder 23 facing the fixing belt 20 (the nip portion N side). The heater 22 is held in the accommodation recess 23a by being sandwiched together with the heater holder 23 by a connector (described later).

The pair of flange members 32 have a C-shaped belt support portion 32b that is inserted into the inner circumference of the fixing belt 20 to support the fixing belt 20, a flange-shaped belt regulation portion 32c that contacts the end face of the fixing belt 20 to regulate movement (deviation) in the belt width direction, and support recesses 32d into which both end sides of the heater holder 23 and the stay 24 are inserted to support them.

Further, the flange member 32 is provided with a guide groove 32 a extending in the direction in which the fixing belt 20 approaches and separates from the pressure roller 21 .
A pair of side plate members 28 constituting the housing frame of the fixing device 9 are engaged with the guide grooves 32a.
The heating device 19 is attached to the housing frame of the fixing device 9 by inserting the side plate members 28 along the guide grooves 32a. The fixing belt 20 is configured to be movable in the direction toward and away from the pressure roller 21 by the side plate members 28 moving relatively within the guide grooves 32a.

The stay 24 has fitting portions 24a at both longitudinal ends thereof, which protrude toward the heater holder 23. The fitting portions 24a are fitted into stay fitting portions 28b, which are fitted portions of the side plate members 28.
The fitting portion 24a and the guide groove 32a are disposed on the same straight line along the direction in which the side plate member 28 enters, as indicated by the dashed arrow in the figure.

The fitting portions 24a of the stays 24 and the stay fitting portions 28b of the side plate members 28 are fitted together to determine the relative positions and also to define the distance (longitudinal distance) between the pair of side plate members 28.
Since the side plate members 28 are supported by the stays 24 in this manner, the housing frame of the fixing device 9 is stabilized.

The width of the recess in the fitting portion 24a of the stay 24 only needs to be wide enough to fit into the stay fitting portion 28b of the side plate member 28, and can be selected appropriately depending on the thickness of the side plate member 28.

To ensure the rigidity of the stay 24, it is preferable that the stay 24 be made of an iron-based metal material such as stainless steel or SECC (electro-galvanized steel sheet).

FIG. 5 is a side view of the fixing device according to the present embodiment, and FIG. 6A is a perspective view of the fixing device according to the present embodiment.
6B and 6C are schematic diagrams of the housing frame of the fixing device 9, with FIG. 6B showing the configuration of the fixing device of this embodiment and FIG. 6C showing the configuration of a conventional fixing device.

The housing frame of the fixing device in this embodiment has a support plate member 29 arranged on the pressure roller 21 side, and a pair of side plate members 28 arranged on both longitudinal ends of the support plate member 29. The side plate member 28 and the support plate member 29 are assembled by fitting the support plate fitting protrusions 28d provided on the side plate member 28 into fitting holes 29b provided on the support plate member 29.

The side plate member 28 is provided with a bearing 28c that supports the rotation shaft of the pressure roller 21. The pressure roller 21 is rotatably supported by the side plate member 28 with both ends of the rotation shaft attached to the bearings 28c.

The side plate member 28 is generally U-shaped with an opening for supporting the pressure roller 21, and two sides of the generally U-shaped member have protruding ends 28a whose widths gradually decrease toward the tips.
The protruding ends 28a are provided on two sides of the substantially U-shaped configuration, and two are provided on each of the pair of left and right side plate members 28, so that the housing frame has four protruding ends 28a as a whole.

A drive transmission gear 31 is provided as a drive transmission member on one end side of the rotation shaft of the pressure roller 21. The drive transmission gear 31 is arranged in a state where it is exposed outside the side plate member 28 when the pressure roller 21 is supported by the side plate member 28. As a result, when the fixing device 9 is mounted on the image forming device 100 (installed on the fixing device installation frame 105), the drive transmission gear 31 is connected to a gear provided on the image forming device, and is in a state where it can transmit driving force from the drive source.

The fixing belt 20 is supported by the flange member 32 in a so-called free belt manner, in which no circumferential tension is applied when the belt is not rotating.

A pair of springs (not shown) are provided between each flange member 32 and the support plate member 29 as biasing members. Each spring biases the flange member 32 toward the pressure roller 21, so that the fixing belt 20 is pressed against the pressure roller 21, and a nip portion N is formed between the fixing belt 20 and the pressure roller 21.

The pair of side plate members 28 are held by at least one of the separation plate member 25 , the guide plate member 26 , and the stay 24 on the fixing belt 20 side.
It is preferable that the support be held by two or more members selected from the separation plate member 25, the guide plate member 26, and the stay 24. As a combination of two members, the separation plate member 25 and the guide plate member 26 are preferable.

As shown in FIG. 6C, the conventional fixing device includes a fixing stay 40 as a member that constitutes the housing frame. The fixing stay 40, together with the support plate member 29, positions and fixes the side plate member 28, stabilizing the housing frame.

In contrast, in the fixing device according to the present invention shown in FIG. 6(B), the side plate member 28 can be positioned and fixed by at least one of the existing components, the separation plate member 25, the guide plate member 26, and the stay 24 (not shown), so the fixing stay 40, which is a large component that configures one of the longitudinal sides of the housing frame, can be omitted, and the housing frame can be stabilized while realizing a reduction in the weight of the fixing device 9 and in the parts costs. By stabilizing the housing frame, it is also possible to prevent the components arranged inside from falling or falling off.

The side plate members 28 are held by the separation plate members 25 in the following manner.
Either one of the longitudinal ends of the separation plate member 25 or the side plate member 28 has an engaging portion, and the other has an engaged portion, and the relative positions are determined by engagement between the engaged portion and the engaging portion, and the separation distance between the pair of side plate members 28 is determined.
The manner of engagement includes fitting and fastening.

The side plate members 28 are held by the separation plate member 25 disposed above the fixing belt 20, so that the separation distance between the upper sides of the pair of side plate members 28 is defined.
In addition, since the separation distance on the pressure roller 21 side is determined by the support plate member 29, the separation distance on the fixing belt 20 side is determined by the separation plate member 25 arranged on the fixing belt 20 side, thereby ensuring a stable state of the housing frame of the fixing device 9.

The side plate members 28 are held by the guide plate members 26 in the following manner.
Either one of the longitudinal ends of the guide plate member 26 or the side plate member 28 has an engaging portion, and the other has an engaged portion, and the relative position is determined by the engaging portion engaging with the engaged portion, and the separation distance between the pair of side plate members 28 is determined.
The manner of engagement includes fitting and fastening.

The side plate members 28 are held by the guide plate members 26 disposed below the fixing belt 20, so that the separation distance between the lower sides of the pair of side plate members 28 is defined.
In addition, since the separation distance on the pressure roller 21 side is determined by the support plate member 29, the separation distance on the fixing belt 20 side is determined by the guide plate member 26 arranged on the fixing belt 20 side, thereby ensuring a stable state of the housing frame of the fixing device 9.

The side plate members 28 are held by the stays 24 in the following manner.
Either the longitudinal end of the stay 24 or the side plate member 28 has an engaging portion, and the other has a fitted portion, and the relative position is determined by the engaging portion engaging with the fitting portion, and the separation distance between the pair of side plate members 28 is determined.
For example, as shown in FIGS. 3 and 4, the fitting portions 24a at both ends of the stay 24 in the longitudinal direction may be fitted into stay fitting portions 28b which are fitted portions of the side plate members 28. In the embodiment shown in FIG.

The distance on the pressure roller 21 side is determined by the support plate member 29, and the distance on the fixing belt 20 side is determined by the stay 24 arranged on the fixing belt 20 side, so that the housing frame of the fixing device 9 is in a stable state.

The separation plate member 25, guide plate member 26, and stay 24 that hold the side plate member 28 are preferably made of metal from the standpoints of dimensional stability, strength, and thermal expansion.

In addition, in the engagement between the separation plate member 25 and the side plate member 28, and in the engagement between the guide plate member 26 and the side plate member 28, it is preferable to have a plurality of combinations of engaging portions and engaged portions.
It is also preferable to have a plurality of different combinations of engaging portions and engaged portions.

As a combination of an engaging portion and an engaged portion, it is preferable to provide, for example, a combination in which the separation distance between a pair of side plate members 28 is determined by the separation plate member 25, and a combination in which the relative positions of the side plate member 28 and the separation plate member 25 are determined to determine the separation distance between the separation plate member 25 and the fixing belt 20.

Similarly, it is preferable to have a combination in which the guide plate member 26 determines the distance between the pair of side plate members 28, and a combination in which the guide plate member 26 determines the distance between the guide plate member 26 and the fixing belt 20.

7 to 11 are explanatory diagrams showing examples in which the separation plate member 25 holds the side plate members 28. FIG.
Although an example of holding by the separation plate member 25 is shown in Figs. 7 to 11, the guide plate member 26 may have a similar configuration.
In the drawing, of the pair of side plate members 28, the left side plate member is indicated as 28(L) and the right side plate member is indicated as 28(R).

First Embodiment
7, both longitudinal ends of the separation plate member 25 have curved surfaces facing the side plate members 28. These curved surfaces are provided with screw holes 301 as engaging portions. On the other hand, the side plate members 28 are provided with screw holes 201 as engaged portions at predetermined positions.
Screw members are inserted from the outside through the screw holes 301 of the separation plate member 25 and the screw holes 201 of the side plate members 28 to fasten the separation plate member 25 and the side plate members 28 together.

As a result, the distance between the pair of side plate members 28 is determined by the length of the separation plate member 25 .
In addition, since the separation plate member 25 is positioned relative to the side plate members 28, the distance between the separation plate member 25 and the fixing belt 20 is determined.
In addition, in FIG. 7, two screw holes are provided at one engagement point, but the number of screw holes is not limited to this.

Second Embodiment
8, both longitudinal ends of the separation plate member 25 have curved surfaces facing the side plate member 28. The curved surfaces are provided with a screw hole 301 as an engaging portion and two bosses (convex portions) 302. Meanwhile, the side plate member 28 is provided at predetermined positions with a screw hole 201 as an engaged portion and a fitting hole 202 into which the boss 302 fits.
The boss 302 of the separation plate member 25 is fitted into the fitting hole 202 of the side plate member 28, and a screw member is inserted from the outside through the screw hole 301 of the separation plate member 25 and the screw hole 201 of the side plate member 28 to fasten the separation plate member 25 and the side plate member 28 together.

In this embodiment, the separation plate member 25 and the side plate members 28 are fastened and fixed together, so that the distance between the pair of side plate members 28 is determined by the length of the separation plate member 25 .
Furthermore, the relative positions of the separation plate member 25 and the side plate members 28 are determined by the engagement of the boss 302 with the engagement hole 202 , and the distance between the separation plate member 25 and the fixing belt 20 is determined.
In addition, in FIG. 8, one screw hole, two bosses and fitting holes are provided at one engagement point, but the number of each is not limited to this.

Third Embodiment
9, both longitudinal ends of the separation plate member 25 have curved surfaces, part of which faces the side plate member 28. The curved surfaces are provided with screw holes 301 as engaging portions. They also have convex structures 303 as engaging portions that extend horizontally without bending. Meanwhile, the side plate member 28 is provided at predetermined positions with screw holes 201 as engaged portions and fitting holes 203 into which the convex structures 303 fit.
The convex structure 303 of the separation plate member 25 is engaged with the engaging hole 203 of the side plate member 28, and a screw member is inserted from the outside through the screw hole 301 of the separation plate member 25 and the screw hole 201 of the side plate member 28 to fasten the separation plate member 25 and the side plate member 28 together.

In this embodiment, the separation plate member 25 and the side plate members 28 are fastened and fixed together, so that the distance between the pair of side plate members 28 is determined by the length of the separation plate member 25 .
Furthermore, the relative positions of the separation plate member 25 and the side plate members 28 are determined by the engagement of the convex structures 303 with the engagement holes 203 , and the separation distance between the separation plate member 25 and the fixing belt 20 is determined.
In addition, in FIG. 9, one screw hole, one convex structure, and one fitting hole are provided at one engagement point, but the number of each is not limited to this.

Fourth Embodiment
10, both longitudinal ends of the separation plate member 25 have horizontally extending convex structures 303 and engaging recesses 304 as engaging portions. On the other hand, at predetermined positions of the side plate member 28, there are provided, as engaged portions, fitting holes 203 into which the convex structures 303 fit, and engaging recesses 204 that engage with the engaging recesses 304.
The convex structure 303 of the separation plate member 25 is fitted into the fitting hole 203 of the side plate member 28 , and the engagement recess 304 of the separation plate member 25 is engaged with the engagement recess 204 of the side plate member 28 .

In this embodiment, the engagement between the engagement recesses 304 and 204 defines the separation distance between the pair of side plate members 28 to the length of the separation plate member 25 .
Furthermore, the relative positions of the separation plate member 25 and the side plate members 28 are determined by the engagement between the convex structures 303 and the engagement holes 203 , and the separation distance between the separation plate member 25 and the fixing belt 20 is determined.
The shape of the engagement recess and the shape of the convex structure and the fitting hole are not limited to this.

Fifth Embodiment
11, both longitudinal ends of the separation plate member 25 have horizontally extending convex structures 303 as engaging portions, and engaging recesses 305 on the curved side surfaces. Meanwhile, at predetermined positions of the side plate member 28, there are provided, as engaged portions, fitting holes 203 into which the convex structures 303 fit, and engaging recesses 205 that engage with the engaging recesses 305.
The convex structure 303 of the separation plate member 25 is fitted into the fitting hole 203 of the side plate member 28 , and the engagement recess 305 of the separation plate member 25 is engaged with the engagement recess 205 of the side plate member 28 .

In this embodiment, the engagement between the engagement recesses 305 and 205 defines the separation distance between the pair of side plate members 28 to the length of the separation plate member 25 .
Furthermore, the relative positions of the separation plate member 25 and the side plate members 28 are determined by the engagement between the convex structures 303 and the engagement holes 203 , and the separation distance between the separation plate member 25 and the fixing belt 20 is determined.
The shape of the engagement recess and the shape of the convex structure and the fitting hole are not limited to this.

Next, we will explain the configuration for installing the fixing device 9 of this embodiment on the fixing device installation frame (hereinafter also simply referred to as the "installation frame") 105 of the image forming device 100 and positioning and fixing it.

Fig. 12 is a perspective view showing the fixing device 9 and the fixing device installation frame 105 according to this embodiment, and Fig. 13(A) is a perspective view showing the fixing device 9 according to this embodiment mounted on the fixing device installation frame 105. Figs. 13(B) and (C) are schematic diagrams of the housing frame of the fixing device 9 and the installation frame 105 of the image forming apparatus, with Fig. 13(B) showing the configuration of this embodiment and Fig. 13(C) showing the conventional configuration.
FIG. 14 is a partial perspective view of FIG. 13 as seen from the opposite side.

The support plate member 29 of the fixing device 9 has a through hole 29a through which a fixing means is inserted for positioning and fixing it between the image forming device 100 (installation frame 105).

The installation frame 105 of the image forming apparatus 100 has a slit-shaped insertion hole 111 into which the protruding end 28a of the side plate member 28 is inserted, and a fixing portion 112 provided with a fixing means that engages or fits into the through hole 29a of the support plate member 29.
The insertion hole 111 is provided in the installation frame wall portion 110 .
The fixing portion 112 is provided at an end of the side wall 120 of the installation frame 105 so as to face the installation frame wall portion 110 .

As shown in FIG. 12, when the fixing device 9 is attached to the installation frame 105, the four protruding ends 28a of the side plate members 28 are inserted into the corresponding insertion holes 111 in the direction indicated by the dashed lines in the figure.
The manner in which the fixing device 9 is positioned and fixed to the installation frame 105 is determined by the position, shape and size of the protruding end 28 a and the position, shape and size of the insertion hole 111 .

As shown in FIGS. 13 and 14 , the four protruding ends 28 a of the side plate members 28 of the fixing device 9 are inserted into the four corresponding through-holes 111 .
The pair of side plate members 28 are also supported by the installation frame wall portion 110 of the installation frame 105 on the fixing belt 20 side. In addition, since the housing frame of the fixing device 9 is supported in the vertical direction, the posture of the fixing device 9 is stable in the vertical and horizontal directions.

In the example shown in FIG. 13, one of the two through holes 29a provided on both ends of the support plate member 29 in the longitudinal direction is fastened to the fixed portion 112 by a screw 115, and the other is engaged with an embossment 114 provided on the fixed portion. In this way, the fixing device 9 is positioned and fixed in the front-rear direction relative to the installation frame 105. The fixing device 9 is positioned in the up-down and left-right directions by inserting the protruding end 28a into the insertion hole 111, as described above.

13C, the conventional fixing device includes a fixing stay 40 as a member that constitutes the housing frame. The fixing stay 40, together with a support plate member 39, positions and fixes the side plate member 28, thereby stabilizing the housing.
In contrast, in the fixing device 9 of the present invention shown in Figure 13 (B), the side plate member 28 is positioned and fixed by at least one of the separation plate member 25, the guide plate member 26, and the stay 24 (not shown), and the side plate member 28 is also held by the installation frame wall portion 110, so that the housing frame can be sufficiently stable even if the fixing stay 40 is omitted.
By stabilizing the housing frame, the drive transmission from the image forming apparatus 100 and the paper transport are also stabilized, so that highly accurate images can be obtained.

The protruding end 28a of the side plate member 28 and the insertion hole 111 of the installation frame wall portion 110 are described with reference to Figures 15 to 17.

FIG. 15 is a diagram for explaining the dimensions of the side plate member 28. As shown in FIG.
The plate thickness of the protruding end 28a of the side plate member 28 is indicated by T. Furthermore, the length of the upper protruding end 28a of each of the two sides of the substantially U-shaped side plate member 28 is indicated by h1, and the length of the lower protruding end 28a is indicated by h2.

FIG. 16 is a diagram for explaining the dimensions of the insertion hole 111 of the installation frame wall portion 110. As shown in FIG.
The length of the opening of the two upper insertion holes 111 is indicated as H1, and the length of the opening of the two lower insertion holes 111 is indicated as H2.
The insertion holes 111 have a slit-like shape with a wide central portion, and the width of the narrowest portion is indicated by W. Of the four insertion holes 111, the upper right insertion hole 111 in the figure has a width W1, the lower right insertion hole 111 has a width W2, the upper left insertion hole 111 has a width W3, and the lower left insertion hole 111 has a width W4.

An example of the setting of the length h of the tip portion 28a and the length H of the insertion hole 111 will be described.
The two upper insertion holes 111 are provided at targeted positions for positioning and fixing the tip portion 28a, and the length H1 of the two upper insertion holes 111 is set to be approximately the same as the length h1 of the upper tip portion 28a.
On the other hand, the length H2 of the two lower insertion holes 111 is set to be greater than the length h2 of the lower protruding end 28a.

With the above settings, when the tip 28a is inserted, the upper tip 28a fits into the upper insertion hole 111, and is positioned and fixed in the correct position.
On the other hand, the two lower insertion holes 111 have openings longer than the lower end 28a into which the insertion is performed, so that the end 28a is not fixed in the vertical direction. This makes it possible to absorb errors due to dimensional variations and installation errors.

An example of the setting of the plate thickness T of the tip portion 28a and the width W of the insertion hole 111 will be described.
First, a case where the side plate members 28 are positioned only by the separation plate member 25 will be described as a configuration of the housing frame of the fixing device 9. As shown in FIG.
In the above embodiment, only the upper sides of the side plate members 28 are held and positioned by the separation plate member 25 disposed above the fixing device 9. The separation distance between the pair of side plate members 28 is accurately determined only on the upper sides.

In this case, the two lower insertion holes 111 are set to the desired separation distance between the pair of side plate members 28, and the widths W2 and W4 of the two lower insertion holes 111 are set to be approximately the same as the plate thickness T of the tip 28a. Furthermore, the widths W1 and W2 of the two lower insertion holes 111 in the two upper rows are set to be wider than the plate thickness T of the tip 28a.

By setting in this manner, the distance between the lower side of the side plate member 28 whose protruding end 28a is inserted into the insertion hole 111 is also accurately determined.
Since the separation distance on the upper side of the side plate member 28 is accurately determined by the separation plate member 25, there is no need to adjust it by being held by the installation frame 105. Conversely, in order to avoid problems such as distortion caused by interference from the installation frame 105, it is preferable that the widths W1 and W3 of the two upper insertion holes 111 are set wider than the upper end portion 28a to be inserted, with some play.

Next, a configuration of the housing frame of the fixing device 9 in which the side plate members 28 are positioned only by the guide plate members 26 will be described.
In the above embodiment, the side plate members 28 are held and positioned only at their lower sides by the guide plate members 26 disposed below the fixing device 9. The separation distance between the pair of side plate members 28 is accurately determined only at their lower sides.

In this case, the two upper insertion holes 111 are set to the desired separation distance between the pair of side plate members 28, and the widths W1 and W3 of the two upper insertion holes 111 are set to be approximately the same as the plate thickness T of the tip portion 28a, while the widths W2 and W4 of the two lower insertion holes 111 are set to be wider than the plate thickness T of the tip portion 28a.
By setting it in this way, the separation distance on the upper side of the side plate member 28 where the protruding end 28a is inserted into the insertion hole 111 is also accurately determined. Also, the influence of interference from the installation frame 105 can be avoided.

FIG. 17 is a partial perspective view of the fixing device 9 and the installation frame 105, and also shows an enlarged view of the insertion hole 111. As shown in FIG.
As shown in FIG. 17, the insertion hole 111 has a wide portion 111b in which the central portion of the slit is expanded with respect to a region 111a in which the protruding end portion 28a of the side plate member 28 is disposed.

When the fixing device 9 is attached to the installation frame 105, there is a possibility that the tip 28a may be inserted in a position that is offset from the intended position of the insertion hole 111. Even in such a case, by providing the wide portion 111b as a clearance (scoop), the installation frame wall portion 110 does not become an obstacle and the attachment can be performed. The tip 28a is shaped so that its width gradually decreases toward the tip, and the wide portion 111b is also shaped so as to be inclined toward the region 111a. Therefore, even if the tip 28a is inserted in a position that is offset (the wide portion 111b), the tip 28a is smoothly guided to the intended position (the region 111a).
With this configuration, the workability when attaching and detaching the fixing device 9 as a unit is improved, and assembly is also facilitated.

The through hole 29a of the support plate member 29 and the fixing portion 112 of the installation frame 105 are described with reference to Figures 18 and 19.

18A, the installation frame 105 is provided with a pair of fixing parts for fixing the support plate member 29. The fixing parts 112 are provided from the ends of the side walls 120 of the installation frame 105 to face the installation frame wall part 110, and include an embossment 114 that fits into the embossed through holes 292 of the through holes 29a of the support plate member 29, and a screw hole 113.
18B is a diagram showing a state in which the fixing device 9 is attached. The embossed portion 114 fits into the embossed through-hole 292 of the support plate member 29, thereby positioning the fixing device 9. The screw hole 113 is fastened to the screw hole 291 of the support plate member 29 by a screw 115, thereby fixing the fixing device 9.

On the other hand, as described with reference to FIGS. 15 and 16, the protruding ends 28a of the side plate members 28 are inserted into the insertion holes 111 of the installation frame wall portions 110, and the fixing device 9 is also positioned by being fitted thereto.
Therefore, as shown in Figures 19 (A) and (B), the fixing portion 112 may be provided with only a screw hole 113, and similarly the support plate member 29 may be provided with only a screw hole 291, and both may be fastened together with a screw 115.
By configuring the fixing device 9 only with the screw 115, it is possible to omit the space required for providing the embossment 114 for positioning and the embossed through hole 292. This makes it possible to reduce the width of the support plate member 29 indicated by the arrow S in the figure, and therefore the width of the fixing device 9 itself can also be reduced, making it possible to realize a compact device.
Furthermore, by using the support plate member 29, together with the side plate member 28, as a member that contributes to improving the mounting accuracy and the stability of the housing frame, it is possible to optimize the size and function of the device.

The fixing device of this embodiment and the image forming device equipped with this fixing device can achieve a more compact, lightweight, and less expensive device, as well as stabilization and accurate positioning of the housing frame. It can also prevent scratches and damage caused by the dropping or falling off of various components arranged between the pair of side plate members 28 of the fixing device 9. It can also prevent image defects caused by such problems.

The above configuration is also applicable to fixing devices and image forming apparatuses of different embodiments.
An example of a fixing device and an image forming apparatus to which the present invention is applied will be described below. An example of a heater 22 and a heater holder 23 provided in a heating device 19 of the fixing device 9 will also be described.

The fixing device 9 shown in FIG. 20 is equipped with a planar or plate-shaped heater 22 having a resistance heating element 56 provided on a substrate 55 as a heat source. The substrate 55 is made of ceramics such as alumina and aluminum nitride, or materials having heat resistance and insulation properties such as glass, mica, and polyimide. The substrate 55 may also be made of a metal material such as stainless steel, iron, or aluminum on which an insulating layer is formed. The resistance heating element 56 is formed by applying a paste made of a mixture of silver palladium (AgPd) and glass powder to the surface of the substrate 55 by screen printing or the like, and then baking the substrate 55. The resistance heating element 56 is covered with an insulating layer 57. The insulating layer 57 is made of materials such as heat-resistant glass, ceramic, and polyimide.

21, the heater 22 is formed in a rectangular plate shape and is arranged so that its longitudinal direction coincides with the longitudinal direction of the fixing belt 20. A plurality of resistance heating elements 56 are arranged at intervals along the longitudinal direction of the substrate 55 (heater 22). A plurality of electrode portions 58 and a plurality of power supply lines 59 are provided on the surface of the substrate 55 on which each resistance heating element 56 is provided. Each resistance heating element 56 is connected in parallel to each electrode portion 58 provided at both longitudinal ends of the substrate 55 via the power supply lines 59. Each resistance heating element 56 and each power supply line 59 are covered by an insulating layer 57. On the other hand, each electrode portion 58 is not covered by the insulating layer 57 and is exposed so that a connector as a power supply terminal can be connected.

As shown in FIG. 20, the heater 22 is held by a heater holder 23 and is positioned so as to be in contact with the inner circumferential surface of the fixing belt 20. Therefore, when the heater 22 generates heat, the fixing belt 20 is heated from the inside.

The fixing belt 20 and pressure roller 21 are basically the same as the pressure roller in the above embodiment.

The heater holder 23 is provided integrally with a guide member 66. The guide member 66 is disposed on the upstream and downstream sides of the nip portion N in the rotation direction of the fixing belt 20. When the fixing belt 20 rotates, the guide member 66 contacts the inner peripheral surface of the fixing belt 20 to guide the fixing belt 20 from the inside.

Further, a temperature sensor 67 serving as a temperature detection member for detecting the temperature of the heater 22 is disposed on the inner side of the fixing belt 20. The temperature sensors 67 are pressurized by a spring 70.
The temperature sensor 67 shown in FIG. 20 is a contact-type temperature sensor that detects the temperature by contacting the surface of the heater 22 opposite the nip portion N side, but it may also be a non-contact-type temperature sensor that is arranged in a non-contact manner with the heater 22 and detects the ambient temperature in the vicinity of the heater 22.

In the fixing device 9, the heater 22 is supplied with power from a power source provided in the image forming apparatus body, causing the resistance heating element 56 to generate heat. This heats the fixing belt 20. The amount of heat generated by the heater 22 is controlled based on the temperature of the heater 22 detected by the temperature sensor 67, so that the temperature of the fixing belt 20 is maintained at a predetermined temperature (fixing temperature). In this state, as shown in FIG. 20, a sheet of paper P carrying unfixed toner enters between the fixing belt 20 and the pressure roller 21 (nip portion N), whereby the unfixed toner on the sheet of paper P is pressurized and heated, and the toner image is fixed to the sheet of paper P.

The temperature sensor 67 may be located at the center M of the nip N in the paper transport direction as shown in FIG. 20, or may be located upstream of the center M of the nip N in the paper transport direction as shown in the embodiment in FIG. 22. In other words, the temperature sensor 67 may be located on the entrance side of the nip N. The entrance side of the nip N is an area where heat from the fixing belt 20 is particularly likely to be lost by the paper P entering the nip N. Therefore, by detecting the temperature on the entrance side with the temperature sensor 67, the fixability of the image can be ensured and the occurrence of fixing offset, in which the toner image cannot be sufficiently heated, can be effectively suppressed.

The fixing device 9 shown in FIG. 23 has a pressure roller 69 disposed on the opposite side of the fixing belt 20 from the pressure roller 21 side. The pressure roller 69 is a counter rotating member that rotates opposite the fixing belt 20 as a rotating member. This pressure roller 69 and the heater 22 are configured to sandwich and heat the fixing belt 20. On the other hand, on the pressure roller 21 side, a nip forming member 68 is disposed on the inner circumference of the fixing belt 20. The nip forming member 68 is held by the stay 24. The nip forming member 68 and the pressure roller 21 sandwich the fixing belt 20 to form a fixing nip N.

In the fixing device 9 shown in FIG. 24, the pressure roller 69 described above is omitted, and the heater 22 is formed in an arc shape to match the curvature of the fixing belt 20 in order to ensure the circumferential contact length between the fixing belt 20 and the heater 22. The rest of the configuration is the same as that of the fixing device 9 shown in FIG. 23.

The fixing device 9 shown in FIG. 25 is composed of a heating assembly 92, a fixing roller 93 as a fixing member, and a pressure assembly 94 as an opposing member. The heating assembly 92 has the heater 22, heater holder 23, stay 24, and heating belt 99 as a rotating member described in the previous embodiment. The fixing roller 93 is an opposing rotating member that rotates opposite the heating belt 99 as a rotating member. The fixing roller 93 is composed of a solid iron core 93a, an elastic layer 93b formed on the surface of the core 93a, and a release layer 93c formed on the outside of the elastic layer 93b. A pressure assembly 94 is provided on the opposite side of the fixing roller 93 from the heating assembly 92 side. The pressure assembly 94 has a nip forming member 95 and a stay 96 arranged therein, and a pressure belt 97 arranged rotatably so as to enclose the nip forming member 95 and the stay 96. Then, the paper P is passed through the fixing nip N2 between the pressure belt 97 and the fixing roller 93, where it is heated and pressurized to fix the image.

The image forming apparatus according to the present invention is not limited to the color image forming apparatus shown in FIG. 1, but may also be a monochrome image forming apparatus, a copier, a printer, a facsimile, or a combination machine of these.

For example, the present invention can be applied to an image forming apparatus having a configuration as shown in FIG.
26 includes an image forming means 80 including a photosensitive drum and the like, a paper transport section including a pair of timing rollers 81 and the like, a paper feed device 82, a fixing device 9, a paper discharge device 84, and a reading section 85. The paper feed device 82 includes a plurality of paper feed trays, each of which stores paper of a different size.

The reading unit 85 reads the image of the document Q. The reading unit 85 generates image data from the read image. The paper feeder 82 stores multiple sheets of paper P and sends the sheets P to the transport path. The timing rollers 81 transport the sheets P on the transport path to the image forming means 80.

The image forming means 80 forms a toner image on the paper P. Specifically, the image forming means 80 includes a photosensitive drum, a charging roller, an exposure device, a developing device, a replenishing device, a transfer roller, a cleaning device, and a charge removal device. The toner image represents, for example, an image of the original Q. The fixing device 9 heats and pressurizes the toner image to fix the toner image to the paper P. The paper P with the fixed toner image is transported to the paper discharge device 84 by a transport roller or the like. The paper discharge device 84 discharges the paper P outside the image forming apparatus 100.

Next, the fixing device 9 of this embodiment will be described. Descriptions of configurations common to the fixing device of the previous embodiment will be omitted as appropriate.

As shown in FIG. 27, the fixing device 9 includes a fixing belt 20, a pressure roller 21, a heater 22, a heater holder 23, a stay 24, a temperature sensor 67, etc.

A fixing nip N is formed between the fixing belt 20 and the pressure roller 21. The nip width of the fixing nip N is 10 mm, and the linear speed of the fixing device 9 is 240 mm/s.

The fixing belt 20 has a polyimide base and a release layer, and does not have an elastic layer. The release layer is made of a heat-resistant film material, such as fluororesin. The outer diameter of the fixing belt 20 is approximately 24 mm.

The pressure roller 21 includes a core metal 21a, an elastic layer 21b, and a release layer 21c. The pressure roller 21 has an outer diameter of 24 to 30 mm, and the elastic layer 21b has a thickness of 3 to 4 mm.

The heater 22 includes a base material, a heat insulating layer, a conductor layer including a resistive heating element, and an insulating layer, and is formed with a total thickness of 1 mm. The width Y of the heater 22 in the cross-arrangement direction is 13 mm.

28, the conductor layer of the heater 22 includes multiple resistive heating elements 56, power supply lines 59, and electrode portions 58A to 58C. In this embodiment, as shown in the enlarged view of FIG. 28, the multiple resistive heating elements 56 are divided in the arrangement direction to form divided regions B (however, in FIG. 28, only the enlarged view of the divided regions B is shown, but in reality, divided regions are provided between all of the resistive heating elements 56). The resistive heating elements 56 form three heating sections 35A to 35C. By passing electricity through the electrode portions 58A and 58B, the heating sections 35A and 35C generate heat. By passing electricity through the electrode portions 58A and 58C, the heating section 35B generates heat. For example, when performing a fixing operation on small-sized paper, the heating section 35B can be made to generate heat, and when performing a fixing operation on large-sized paper, all of the heating sections can be made to generate heat.

As shown in FIG. 29, the heater holder 23 has a recess 23b that houses and holds the heater 22. The recess 23b is formed on the heater 22 side of the heater holder 23. The recess 23b is composed of a surface (bottom surface) 23b1 formed in a rectangle (rectangle) of approximately the same size as the heater 22, and four walls (side surfaces) 23b2, 23b3 arranged to intersect with the surface 23b1 along the four sides that form the outline of the surface 23b1. Of the pair of walls 23b2 arranged in a direction intersecting the longitudinal direction X of the heater 22 (arrangement direction of the resistance heating element 56), one wall 23b2 may be omitted, and the recess 23b may be configured to open at one end of the longitudinal direction of the heater 22.

As shown in FIG. 30, the heater 22 and heater holder 23 are held by a connector 86. The connector 86 has a housing made of resin (e.g., LCP) and a number of contact terminals provided within the housing.

The connector 86 is attached so as to sandwich the heater 22 and heater holder 23 from the front and back sides together. In this state, each contact terminal comes into contact (pressure welds) with each electrode portion of the heater 22, electrically connecting the heat generating portion to the power supply provided in the image forming device via the connector 86. This makes it possible to supply power from the power supply to the heat generating portion.

The flange members 32 are inserted into both ends of the stays 24 in the direction of the arrows in FIG. 30, and hold both ends of the fixing belt 20 from the inside of the belt.
The flange member 32 is fixed to the housing of the fixing device 9. As a manner of fixing, the configuration according to the present invention (see FIG. 4) can be applied.

The direction in which the connector 86 is attached to the heater 22 and heater holder 23 is the cross direction of the heater arrangement (see the direction of the arrow from the connector 86 in Figure 30). When the connector 86 is attached to the heater holder 23, a convex portion on one of the connector 86 and the heater holder 23 may engage with a concave portion on the other, and the convex portion may move relatively within the concave portion. The connector 86 is attached to the heater 22 and heater holder 23 on one side of the arrangement direction, opposite the side on which the drive motor of the pressure roller 21 is provided.

Figure 31 (A) shows the arrangement of the temperature sensor 67 and the thermostat 88, which is a current interrupting member.

As shown in FIG. 31A, the temperature sensors 67 are arranged to face the inner circumferential surfaces of the center C and end portions of the fixing belt 20 in the longitudinal direction. One of these temperature sensors 67 is also arranged at a position corresponding to the divided region B (see FIG. 28) between the resistive heating elements of the heater 22.

At the center C side and end sides of the fixing belt 20, thermostats 88 as current-cutting members are arranged to face the inner surface of the fixing belt 20. Each thermostat 88 detects the temperature of the inner surface of the fixing belt 20 or the ambient temperature near the inner surface. If the temperature detected by the thermostat 88 exceeds a preset threshold value, current to the heater 22 is cut off.

As shown in Figures 31(A) and 31(B), a guide groove 32a is provided on the flange member 32 that holds both ends of the fixing belt 20. The guide groove 32a extends in the direction in which the fixing belt 20 approaches and separates from the pressure roller 21. The housing frame (side plate member 28) of the fixing device 9 engages with the guide groove 32a, and the fixing belt 20 is configured to be able to move in the direction in which it approaches and separates from the pressure roller 21 by moving relatively within the guide groove 32a.

The present invention is also applicable to a fixing device having the following configuration.
FIG. 32 is a schematic diagram of a fixing device according to another embodiment to which the present invention can be applied.
32, the fixing device 9 according to this embodiment includes a fixing belt 20 as a rotating body or fixing member, a pressure roller 21 as a counter rotating body or pressure member, a heater 22 as a heat source, a heater holder 23 as a heat source holding member, a stay 24 as a flange member, a temperature sensor (thermistor) 67 as a temperature detection member, and a first highly heat conductive member 89. The temperature sensor 67 detects the temperature of the first highly heat conductive member 89.

The stay 24 abuts the contact surfaces 241 of two vertical portions 240 extending in the thickness direction of the heater 22 etc. against the heater holder 23, and holds the heater holder 23, the first high thermal conductivity member 89, and the heater 22. In the array crossing direction (the up-down direction in the figure), the contact surfaces 241 are provided outside the range in which the resistance heating element 56 is provided. This makes it possible to suppress heat transfer from the heater 22 to the stay 24, and allows the heater 22 to efficiently heat the fixing belt 20.

The heater holder 23 is provided with guide members 66 that guide the fixing belt 20. The guide members 66 are provided on the upstream and downstream sides of the heater 22 in the belt rotation direction. The upstream and downstream guide members 66 are arranged at intervals along the longitudinal direction of the heater 22. Each guide member 66 is formed in a roughly fan shape and has an arc-shaped or convex curved belt-facing surface that extends in the belt circumferential direction so as to face the inner circumferential surface of the fixing belt 20.

22, like the heater shown in FIG. 28 above, has multiple resistance heating elements 56 spaced apart from one another in the longitudinal direction of the heater 22. However, in a configuration in which multiple resistance heating elements 56 are spaced apart from one another, the temperature of the heater 22 in divided regions B, which are the spaces between the resistance heating elements 56, tends to be lower than in the portions where the resistance heating elements 56 are arranged. For this reason, the temperature of the fixing belt 20 also becomes lower in divided region B, and there is a risk that the temperature of the fixing belt 20 will become uneven along the longitudinal direction.

Therefore, in this embodiment, the first highly thermally conductive member 89 is provided to suppress the temperature drop in the divided region B and suppress temperature unevenness in the longitudinal direction of the fixing belt 20. The first highly thermally conductive member 89 will be described in more detail below.

As shown in FIG. 33, the first high thermal conductivity member 89 is disposed between the heater 22 and the stay 24 in the left-right direction of the figure, and is sandwiched in particular between the heater 22 and the heater holder 23. In other words, one surface of the first high thermal conductivity member 89 abuts against the rear surface of the base material 55 of the heater 22, and the other surface of the first high thermal conductivity member 89 (the surface opposite to the one surface) abuts against the heater holder 23.

The first high thermal conductivity member 89 is a plate-like member having a certain thickness, and is set, for example, to a thickness of 0.3 mm, a length in the longitudinal direction of 222 mm, and a width in the transverse direction of the longitudinal direction of 10 mm. In this embodiment, the first high thermal conductivity member 89 is composed of a single plate material, but it may be composed of multiple members. Note that the guide member 66 described in FIG. 32 is omitted in FIG. 33.

The first high thermal conductive member 89 is fitted into the recess 23b of the heater holder 23, and the heater 22 is attached from above, so that the first high thermal conductive member 89 is sandwiched and held between the heater holder 23 and the heater 22. In this embodiment, the longitudinal width of the first high thermal conductive member 89 is set to be approximately the same as the longitudinal width of the heater 22. The longitudinal movement of the first high thermal conductive member 89 and the heater 22 is restricted by both side walls (longitudinal direction restriction parts) 23b1 arranged in a direction intersecting the longitudinal direction of the recess 23b. In this way, the longitudinal positional deviation of the first high thermal conductive member 89 in the fixing device 9 is regulated, so that the heat conduction efficiency can be improved in the target range in the longitudinal direction. In addition, the longitudinal movement of the first high thermal conductive member 89 and the heater 22 is restricted by both side walls (arrangement intersecting direction restriction parts) 23b2 arranged in the longitudinal direction of the recess 64b.

The range in the longitudinal direction (arrow X direction) in which the first high thermal conductivity member 89 is arranged is not limited to the range shown in FIG. 33. For example, as shown in FIG. 34, the first high thermal conductivity member 89 may be arranged only in the longitudinal range in which the resistive heating element 56 is arranged (see the hatched area in FIG. 34).

Also, as shown in the example of FIG. 35, the first high thermal conductivity member 89 can be arranged only over the entire area at a position corresponding to the interval (division area) B in the longitudinal direction (arrow X direction). Note that in FIG. 35, the resistance heating element 56 and the first high thermal conductivity member 89 are shown shifted in the vertical direction of FIG. 35 for convenience, but they are arranged at approximately the same position in the transverse direction (arrow Y direction). The first high thermal conductivity member 89 may be arranged over a part of the transverse direction (arrow Y direction) of the resistance heating element 56, or as shown in the example of FIG. 36, the first high thermal conductivity member 89 may be arranged over the entire transverse direction (arrow Y direction) of the resistance heating element 56.

36, the first high thermal conductivity member 89 can be arranged across the resistance heating elements 56 on both sides that sandwich the interval B in addition to being arranged at a position corresponding to the longitudinal interval B. This "arrangement of the first high thermal conductivity member 89 across the resistance heating elements 56 on both sides" means that the first high thermal conductivity member 89 overlaps at least partially with the resistance heating elements 56 on both sides in the longitudinal direction. The first high thermal conductivity member 89 may be arranged at a position corresponding to all of the intervals B of the heater 22, or may be arranged at a position corresponding to only a portion of the interval B (in this case, one location) as in the example shown in FIG. 36. Here, "arrangement of the first high thermal conductivity member 89 at a position corresponding to the interval B" means that the interval B and the first high thermal conductivity member 89 at least partially overlap in the longitudinal direction.

The pressure of the pressure roller 21 causes the first highly heat conductive member 89 to be sandwiched between the heater 22 and the heater holder 23 and to come into close contact with these members. The first highly heat conductive member 89 comes into contact with the heater 22, thereby improving the thermal conduction efficiency of the heater 22 in the longitudinal direction. The first highly heat conductive member 89 is arranged at a position corresponding to the interval B of the heater 22 in the longitudinal direction, thereby improving the thermal conduction efficiency in the interval B, increasing the amount of heat transferred to the interval B, and raising the temperature in the interval B. This makes it possible to suppress temperature unevenness in the longitudinal direction of the heater 22 and to suppress temperature unevenness in the longitudinal direction of the fixing belt 20. As a result, it is possible to suppress uneven fixing and uneven gloss of the image fixed to the paper. In addition, in order to ensure sufficient fixing performance in the interval B, it is no longer necessary to increase the heat generation amount of the heater 22, and energy saving of the fixing device can be realized. In particular, when the first high thermal conductivity member 89 is arranged over the entire longitudinal area in which the resistive heating element 56 is arranged, the heat transfer efficiency of the heater 22 is improved over the entire area that is primarily heated by the heater 22 (i.e., the image forming area of the paper being passed through), and temperature unevenness in the longitudinal direction of the heater 22 and, by extension, the fixing belt 20 can be suppressed.

Furthermore, by combining the first highly heat conductive member 89 with the resistance heating element 56 having PTC characteristics, it is possible to more effectively suppress excessive heating in non-paper passing areas when small size paper is passed through. The PTC characteristics are such that the resistance value increases as the temperature increases (when a constant voltage is applied, the heater output decreases). In other words, because the resistance heating element 56 has PTC characteristics, the amount of heat generated by the resistance heating element 56 in the non-paper passing areas can be effectively suppressed, and the first highly heat conductive member 89 can efficiently transfer the heat of the non-paper passing areas where the temperature has increased to the paper passing areas, so that the synergistic effect of these two can effectively suppress excessive heating in the non-paper passing areas.

Also, since the temperature of the heater 22 is low around the interval B due to the small amount of heat generated in the interval B, it is preferable to place the first high thermal conductivity member 89. For example, by placing the first high thermal conductivity member 89 at a position corresponding to the expanded divided area C including the area around the interval B shown in FIG. 37, the heat transfer efficiency in the longitudinal direction in the interval B and its periphery can be improved, and temperature unevenness in the longitudinal direction of the heater 22 can be more effectively suppressed. Furthermore, if the first high thermal conductivity member 89 is placed over the entire longitudinal direction of the area in which all the resistance heating elements 56 are placed, temperature unevenness in the longitudinal direction of the heater 22 (fixing belt 20) can be more reliably suppressed.

Next, still another embodiment of the fixing device will be described.
The fixing device 9 shown in Fig. 38 has a second high thermal conductivity member 90 between the heater holder 23 and the first high thermal conductivity member 89. The second high thermal conductivity member 90 is provided at a position different from that of the first high thermal conductivity member 89 in the stacking direction (left-right direction in Fig. 38) of members such as the heater holder 23, the stay 24, and the first high thermal conductivity member 89. More specifically, the second high thermal conductivity member 90 is provided overlapping the first high thermal conductivity member 89. In this embodiment, a temperature sensor (thermistor) 67 is provided as in the embodiment shown in Fig. 32, but Fig. 38 shows a cross section in which the temperature sensor 67 is not provided.

The second high thermal conductivity member 90 is made of a material having a higher thermal conductivity than the base material 55, such as graphene or graphite. In this embodiment, the second high thermal conductivity member 90 is made of a graphite sheet having a thickness of 1 mm. The second high thermal conductivity member 90 may also be made of a plate material such as aluminum, copper, or silver.

As shown in FIG. 39, a plurality of second high thermal conductive members 90 are arranged in the recess 23b of the heater holder 23, and a longitudinal gap is provided between each of the second high thermal conductive members 90. A recess that is one step deeper than the other portions is formed in the portion of the heater holder 23 where the second high thermal conductive member 90 is provided. A gap is provided between the second high thermal conductive member 90 and the heater holder 23 on both sides of the longitudinal direction. This suppresses heat transfer from the second high thermal conductive member 90 to the heater holder 23, and the fixing belt 20 is efficiently heated by the heater 22. Note that the guide member 66 described in FIG. 32 is omitted in FIG. 39.

40 , the second high thermal conductivity members 90 (see the hatched portions) are disposed in the longitudinal direction (direction of the arrow X) at positions corresponding to the interval B so as to overlap at least a portion of the adjacent resistance heating elements 56. Particularly in this embodiment, the second high thermal conductivity members 90 are disposed across the entire interval B.
Note that Figure 40 (and Figure 41 described below) shows a case where the first high thermal conductivity member 89 is arranged over the entire longitudinal direction of the area in which all of the resistive heating elements 56 are arranged, but the arrangement range of the first high thermal conductivity member 89 is not limited to this.

In this embodiment, in addition to the first high thermal conductivity member 89, the second high thermal conductivity member 90 is disposed at a position corresponding to the longitudinal interval B, overlapping at least a portion of the adjacent resistance heating elements 56, thereby further improving the longitudinal heat transfer efficiency at the interval B and more effectively suppressing temperature unevenness in the longitudinal direction of the heater 22. Most preferably, as shown in FIG. 41, the first high thermal conductivity member 89 and the second high thermal conductivity member 90 are provided only over the entire area at the position corresponding to the interval B. This allows the heat transfer efficiency to be particularly improved at the position corresponding to the interval B compared to other areas.

In FIG. 41, for convenience, the resistive heating element 56 and the first and second high thermal conductive members 89 and 90 are shown shifted in the vertical direction of the figure, but they are arranged at approximately the same position in the transverse direction (arrow Y direction). However, this is not limited to this, and the first and second high thermal conductive members 89 and 90 may be arranged in a portion of the resistive heating element 56 in the transverse direction, or may be arranged to cover the entire transverse direction.

In addition, both the first highly thermally conductive member 89 and the second highly thermally conductive member 90 may be formed from the graphene sheet. In this case, the first highly thermally conductive member 89 and the second highly thermally conductive member 90 can be formed with high thermal conductivity in a predetermined direction along the graphene surface, that is, in the longitudinal direction rather than the thickness direction. This makes it possible to effectively suppress temperature unevenness in the heater 22 and the fixing belt 20 in the longitudinal direction.

Graphene is a flake-like powder. Graphene consists of a planar hexagonal lattice structure of carbon atoms, as shown in FIG. 44. A graphene sheet is a sheet of graphene, usually a single layer. A graphene sheet may also contain impurities in a single layer of carbon, or may have a fullerene structure. A fullerene structure is generally recognized as a compound in which an equal number of carbon atoms form polycyclic rings condensed into a cage shape with five-membered and six-membered rings, such as C60, C70 and C80 fullerenes or other closed cage structures with three-coordinated carbon atoms.

Graphene sheets are man-made and can be made, for example, by chemical vapor deposition (CVD).

Commercially available graphene sheets can be used. The size and thickness of the graphene sheets, as well as the number of layers of the graphite sheets described below, are measured, for example, by a transmission electron microscope (TEM).

Graphite, which is a multi-layered graphene, has a large thermal conductivity anisotropy. As shown in FIG. 45, graphite has a layer in which the condensed six-membered ring layer plane of carbon atoms spreads out in a planar shape, and has a crystal structure in which these layers are stacked on top of each other. In this crystal structure, adjacent carbon atoms in the layer form covalent bonds, and carbon atoms between layers form van der Waals bonds. The covalent bonds have a larger bond strength than the van der Waals bonds, and have a large anisotropy between the bonds within the layer and the bonds between the layers. In other words, by forming the first high thermal conductivity member 89 or the second high thermal conductivity member 90 from graphite, the heat transfer efficiency in the longitudinal direction of the first high thermal conductivity member 89 or the second high thermal conductivity member 90 is greater than that in the thickness direction (i.e., the stacking direction of the members), and the heat transfer to the heater holder 23 can be suppressed. Therefore, the temperature unevenness in the longitudinal direction of the heater 22 can be efficiently suppressed, and the heat flowing out to the heater holder 23 can be minimized. Furthermore, by constructing the first high thermal conductivity member 89 or the second high thermal conductivity member 90 from graphite, the first high thermal conductivity member 89 or the second high thermal conductivity member 90 can be endowed with excellent heat resistance that does not oxidize up to approximately 700 degrees.

The physical properties and dimensions of the graphite sheet can be changed as appropriate depending on the functions required of the first highly thermally conductive member 89 or the second highly thermally conductive member 90. For example, the anisotropy of the thermal conduction can be increased by using high-purity graphite or single crystal graphite, or by increasing the thickness of the graphite sheet. Also, in order to increase the speed of the fixing device, a thin graphite sheet can be used to reduce the thermal capacity of the fixing device. Also, if the width of the nip portion N and the heater 22 is large, the longitudinal width of the first highly thermally conductive member 89 or the second highly thermally conductive member 90 can be increased accordingly.

From the viewpoint of increasing mechanical strength, it is preferable that the number of layers of the graphite sheet is 11 or more. The graphite sheet may also partially include single-layer and multi-layer portions.

The second high thermal conductivity member 90 may be arranged in a position corresponding to the interval B (and further to the enlarged divided region C) in the longitudinal direction so as to overlap at least a portion of the adjacent resistance heating element 56, and is not limited to the arrangement shown in FIG. 40. For example, as shown in the example shown in FIG. 42, the second high thermal conductivity member 90A may be arranged to protrude beyond the base material 55 on both sides of the longitudinal cross direction (arrow Y direction). The second high thermal conductivity member 90B may be arranged in the range where the resistance heating element 56 is arranged in the longitudinal cross direction. The second high thermal conductivity member 90C may be arranged in a portion of the interval B.

In another embodiment shown in FIG. 43, a gap is provided in the thickness direction (left-right direction in FIG. 43) between the first highly thermally conductive member 89 and the heater holder 23. In other words, a recess 23c is provided as a heat insulating layer in a partial area of the recess 23b (see FIG. 39) of the heater holder 23 in which the heater 22, the first highly thermally conductive member 89, and the second highly thermally conductive member 90 are arranged.

The relief portion 23c is provided in a portion of the longitudinal direction other than the portion where the second high thermal conductive member 90 (not shown in FIG. 43) is provided. The relief portion 23c is formed by making the depth of the recess 23b of the heater holder 23 deeper than the other portions. This makes it possible to minimize the contact area between the heater holder 23 and the first high thermal conductive member 89, thereby suppressing the transfer of heat from the first high thermal conductive member 89 to the heater holder 23, and enabling the heater 22 to efficiently heat the fixing belt 20.
In addition, in the cross section in the longitudinal direction where second high thermal conductivity member 90 is provided, second high thermal conductivity member 90 abuts against heater holder 23 as in the embodiment shown in FIG.

In addition, in this embodiment, the relief portion 23c is provided in the transverse direction (the vertical direction in FIG. 43) across the entire area in which the resistance heating element 56 is provided. This effectively suppresses heat transfer from the first highly thermally conductive member 89 to the heater holder 23, improving the heating efficiency of the fixing belt 20 by the heater 22. Note that, in addition to a configuration in which a space is provided as in the relief portion 23c, a configuration in which a heat insulating layer is provided with a heat insulating member having a lower thermal conductivity than the heater holder 23 may also be used.

In addition, in this embodiment, the second high thermal conductivity member 90 is provided as a member different from the first high thermal conductivity member 89, but this is not limited to the above. For example, the first high thermal conductivity member 89 may also function as the second high thermal conductivity member 90 by making the portion of the first high thermal conductivity member 89 corresponding to the interval B thicker than the other portions.

For example, aspects of the present invention are as follows.
<1> A fixing device that can be installed in an image forming apparatus,
A housing frame;
a rotatable endless fixing belt;
a heater for heating the fixing belt;
a heater holder for holding the heater;
a stay disposed inside the fixing belt and supporting the heater holder;
a pressure roller that forms a nip portion with the fixing belt;
a guide plate member for guiding a recording medium to the nip portion;
a separation plate member that separates the recording medium that has passed through the nip portion from the fixing belt,
the housing frame includes a support plate member disposed on the pressure roller side, and a pair of side plate members disposed on both ends of the support plate member in a longitudinal direction,
The fixing device is characterized in that the pair of side plate members are held by at least one of the separation plate member, the guide plate member and the stay on the fixing belt side.
<2> Either one of the longitudinal end portions of the separation plate member and the side plate member has an engaging portion, and the other has an engaged portion,
In the fixing device according to <1>, the relative position is determined by the engagement of the engaging portion with the engaged portion, and a separation distance between the pair of separation plate members is defined.
<3> Either one of the longitudinal ends of the guide plate member or the side plate member has an engaging portion, and the other has an engaged portion,
In the fixing device according to <1>, the relative position is determined by the engagement of the engaging portion with the engaged portion, and a separation distance between the pair of separation plate members is defined.
<4> One of the longitudinal end portion of the stay and the side plate member has a fitting portion, and the other has a fitted portion,
In the fixing device according to <1>, the relative position is determined by fitting the fitting portion into the fitted portion, and a separation distance between the pair of separation plate members is defined.
<5> The fixing device according to any one of <1> to <3>, wherein the fixing device has a plurality of combinations of the engaging portion and the engaged portion.
<6> The fixing device according to any one of <1> to <5>, wherein the separation plate member, the guide plate member and the stay are made of metal.
<7> The side plate member has a generally U-shape having an opening for supporting the pressure roller,
The fixing device according to any one of <1> to <6>, wherein the two sides of the substantially U-shaped member have end portions whose widths gradually decrease toward the ends.
<8> The fixing device according to any one of <1> to <7>, wherein the support plate member has a through hole through which a fixing means for fixing the support plate member to the image forming apparatus is inserted.
<9> The image forming apparatus includes a fixing device installation frame,
When the fixing device is installed in the image forming apparatus,
the protruding end of the side plate member is inserted into an insertion hole formed in the fixing device installation frame,
In the fixing device according to any one of <1> to <8>, the fixing means is inserted through the through hole of the support plate member.
<10> An image forming apparatus including the fixing device according to any one of <1> to <9>.
<11> A fixing device installation frame on which the fixing device is installed,
The image forming apparatus described in <10> is characterized in that the fixing device installation frame has a slit-shaped insertion hole that fits into the side plate member of the fixing device, and a fixing portion that fixes the support plate member of the fixing device.
<12> The image forming apparatus according to <11>, wherein the insertion hole has a shape in which a central portion of the slit has a wide portion that does not abut against the side plate member.

Reference Signs List 9 Fixing device 19 Heating device 20 Fixing belt 21 Pressure roller 22 Heater 23 Heater holder 24 Stay 24a Fitting portion 25 Separation plate member 26 Guide plate member 28 Side plate member 28a Projecting end portion 28b Stay fitting portion 28c Bearing 28d Support plate fitting protrusion 29 Support plate member 29a Through hole 291 Screw hole 292 Embossed through hole 29b Fitting hole 31 Gear 32 Flange member 32a Guide groove 100 Image forming apparatus 105 Fixing device mounting frame 110 Mounting frame wall portion 111 Insertion hole 112 Fixing portion 113 Screw hole 114 Embossed 120 Mounting frame side wall

JP 2020-52345 A

Claims (12)

A fixing device that can be installed in an image forming apparatus,
A housing frame;
a rotatable endless fixing belt;
a heater for heating the fixing belt;
a heater holder for holding the heater;
a stay disposed inside the fixing belt and supporting the heater holder;
a pressure roller that forms a nip portion with the fixing belt;
a guide plate member for guiding a recording medium to the nip portion;
a separation plate member that separates the recording medium that has passed through the nip portion from the fixing belt,
the housing frame includes a support plate member disposed on the pressure roller side, and a pair of side plate members disposed on both ends of the support plate member in a longitudinal direction,
a pair of side plate members supported on the fixing belt side by at least one of the separation plate member, the guide plate member and the stay; Either one of the longitudinal ends of the separation plate member or the side plate member has an engaging portion, and the other has an engaged portion,
2. The fixing device according to claim 1, wherein the relative positions are determined by the engagement of the engaging portions with the engaged portions, and a separation distance between the pair of separation plate members is defined. Either one of the longitudinal ends of the guide plate member or the side plate member has an engaging portion, and the other has an engaged portion;
2. The fixing device according to claim 1, wherein the relative positions are determined by the engagement of the engaging portions with the engaged portions, and a separation distance between the pair of separation plate members is defined. One of the longitudinal end of the stay and the side plate member has a fitting portion, and the other has a fitted portion,
2. The fixing device according to claim 1, wherein the relative positions are determined by the engagement of the engagement portions with the mating portions, and a separation distance between the pair of separation plate members is defined. The fixing device according to claim 2 or 3, characterized in that it has a plurality of combinations of the engaging portion and the engaged portion. The fixing device according to claim 1, characterized in that the separation plate member, the guide plate member and the stay are made of metal. the side plate member is substantially U-shaped and has an opening for supporting the pressure roller,
2. The fixing device according to claim 1, wherein the width of each of the two sides of the substantially U-shaped member is gradually reduced toward the tip. The fixing device according to claim 1, characterized in that the support plate member has a through hole through which a fixing means for fixing the support plate member to the image forming device is inserted. the image forming apparatus includes a fixing device installation frame,
When the fixing device is installed in the image forming apparatus,
the protruding end of the side plate member is inserted into an insertion hole formed in the fixing device installation frame,
9. The fixing device according to claim 7, wherein the fixing member is inserted through the through hole of the support plate member. An image forming apparatus comprising the fixing device according to claim 1. a fixing device installation frame on which the fixing device is installed,
11. The image forming apparatus according to claim 10, wherein the fixing device installation frame has a slit-shaped insertion hole that fits with the side plate member of the fixing device, and a fixing portion that fixes the support plate member of the fixing device. The image forming apparatus according to claim 11, characterized in that the insertion hole has a shape in which the center of the slit has a wide portion that does not abut against the side plate member.

Images