JP2024078064A - Belt device, fixing device, and image forming apparatus - Google Patents

Abstract

[Problem] Even when the second frame is configured to be separable from the first frame holding the belt member and multiple roller members, it is possible to easily and accurately determine the position of the belt member in the combined first and second frames. [Solution] A fixing belt 21 (belt member) stretched across multiple roller members 22, 23, 25, a first frame 41 holding the multiple roller members 22, 23, 25 and the fixing belt 21, and a second frame 42 separably combined with the first frame 41 are provided. Then, by combining the second frame 42, which was in a separated state, with the first frame 41, the position of the heating roller 22 (one roller member) among the multiple roller members 22, 23, 25 is regulated in the combined first frame 41 and second frame 42. [Selected Figure] Figure 3

Description

This invention relates to a belt device such as a fixing device or intermediate transfer belt device that has a belt member stretched across multiple roller members, a fixing device that heats and fixes a toner image on a sheet, and an image forming device such as a copier, printer, facsimile, or a combination machine thereof.

Technology for positioning a belt member at a target position in a belt device installed in an image forming device such as a copier or printer has been known for some time (see, for example, Patent Document 1).

Meanwhile, Patent Document 1 discloses a technology that provides a mechanism for controlling the position of a roller member that stretches an intermediate transfer belt (belt member).

In conventional belt devices, when the second frame is configured to be separable from the first frame that holds the belt member and multiple roller members, etc., for the purpose of improving maintainability, it is not possible to accurately determine the position of the belt member in the combined first and second frames.

This invention has been made to solve the problems described above, and aims to provide a belt device, a fixing device, and an image forming device that make it easy to accurately determine the position of the belt member in the combined first and second frames, even when the second frame is configured to be separable from the first frame that holds the belt member and multiple roller members.

The belt device of this invention comprises a belt member stretched over a plurality of roller members, a first frame that holds the plurality of roller members and the belt member, and a second frame that can be separated and combined with the first frame, and the position of one of the plurality of roller members is regulated in the combined first and second frames by combining the second frame, which was in a separated state, with the first frame.

The present invention provides a belt device, a fixing device, and an image forming device that can easily and accurately determine the position of the belt member in the combined first and second frames, even when the second frame is configured to be separable from the first frame that holds the belt member and multiple roller members.

1 is an overall configuration diagram showing an image forming apparatus according to an embodiment of the present invention; FIG. 2 is a diagram illustrating a configuration of a fixing device. FIG. 2 is a diagram illustrating the configuration of first and second frames in the fixing device. 3 is a diagram showing first and second frames in the fixing device in the width direction; FIG. FIG. 13 is a diagram showing a state in which the second frame is separated from the first frame. 10 is a diagram showing the configuration of first and second frames of a fixing device in a first modified example. FIG. 13 is a diagram showing a state in which the second frame is separated from the first frame in the fixing device in the second modified example. FIG.

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that in each drawing, the same or corresponding parts are given the same reference numerals, and the repeated explanations will be appropriately simplified or omitted.

First, the overall configuration and operation of an image forming apparatus 1 will be described with reference to FIG.
In FIG. 1, reference numeral 1 denotes an image forming apparatus as a multifunction machine having a copy function and a printer function, reference numeral 2 denotes a writing unit that emits laser light based on input image information, reference numeral 3 denotes an original transport unit that transports an original D to an original reading unit 4, reference numeral 4 denotes an original reading unit that reads image information of the original D, and reference numeral 7 denotes a paper feed unit in which sheets P such as paper are stored.
Further, reference numeral 9 denotes a registration roller (timing roller) that adjusts the timing of transporting sheet P, 11Y, 11M, 11C, and 11BK denote photosensitive drums on which toner images of each color (yellow, magenta, cyan, and black) are formed, and 12 denotes a charging unit that charges each of the photosensitive drums 11Y, 11M, 11C, and 11BK.
Further, reference numeral 13 denotes a developing unit which develops the electrostatic latent images formed on each of the photosensitive drums 11Y, 11M, 11C, and 11BK, reference numeral 14 denotes a primary transfer bias roller which transfers the toner images formed on each of the photosensitive drums 11Y, 11M, 11C, and 11BK onto a sheet P in a superimposed manner, and reference numeral 15 denotes a cleaning unit which collects untransferred toner on each of the photosensitive drums 11Y, 11M, 11C, and 11BK.
In addition, reference numeral 16 denotes an intermediate transfer belt cleaning section that cleans the intermediate transfer belt 17, reference numeral 17 denotes the intermediate transfer belt onto which multiple color toner images are transferred in superimposed order, reference numeral 18 denotes a secondary transfer bias roller for transferring the color toner image on the intermediate transfer belt 17 onto the sheet P, and reference numeral 20 denotes a fixing device that fixes the toner image (unfixed image) on the sheet P.
Reference numeral 65 denotes an operation panel on which information relating to the printing operation (image forming operation) is displayed and on which operations are performed.

A normal color image forming operation (printing operation) in the image forming apparatus will be described below.
When the image forming apparatus 1 is used as a copier, the user places an original D on the platen, inputs necessary information such as printing conditions into the operation panel 65, and presses the copy button.
As a result, the document D is transported from the document table in the direction of the arrow in the drawing by the transport rollers of the document transport unit 3, and placed on the contact glass 5 of the document reading unit 4. Then, the image information of the document D placed on the contact glass 5 is optically read by the document reading unit 4.

More specifically, the document reading unit 4 scans the image of the document D on the contact glass 5 while irradiating it with light emitted from an illumination lamp. The light reflected by the document D is then imaged on the color sensor via a group of mirrors and a lens. The color image information of the document D is read by the color sensor for each RGB (red, green, blue) color separation light, and then converted into an electrical image signal. Furthermore, based on the RGB color separation image signal, the image processing unit performs color conversion processing, color correction processing, spatial frequency correction processing, and other processing to obtain color image information of yellow, magenta, cyan, and black.

When the image forming device 1 is used as a printer, the user inputs necessary information such as image information and printing conditions from an external input device such as a personal computer that is communicatively connected to the image forming device 1, and the information is acquired by the control unit of the image forming device 1.

The image information for each color, yellow, magenta, cyan, and black, is then sent to the writing unit 2. Then, the writing unit 2 emits laser light (exposure light) based on the image information for each color onto the corresponding photoconductor drums 11Y, 11M, 11C, and 11BK.

Meanwhile, the four photoconductor drums 11Y, 11M, 11C, and 11BK each rotate in the counterclockwise direction in FIG. 1. First, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK are uniformly charged at the portions facing the charging unit 12 (charging process). Thus, a charging potential is formed on the photoconductor drums 11Y, 11M, 11C, and 11BK. Then, the charged surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK reach the respective laser light irradiation positions.
In the writing unit 2, laser beams corresponding to image signals are emitted from four light sources, one for each color. Each laser beam passes through a separate optical path for each color component (yellow, magenta, cyan, black) (this is the exposure process).

The laser light corresponding to the yellow component is irradiated onto the surface of the first photoconductor drum 11Y from the left side of the paper. At this time, the laser light of the yellow component is scanned in the direction of the rotation axis of the photoconductor drum 11Y (main scanning direction, width direction) by the polygon mirror rotating at high speed. In this way, an electrostatic latent image corresponding to the yellow component is formed on the photoconductor drum 11Y after it has been charged by the charging unit 12.

Similarly, the laser light corresponding to the magenta component is irradiated onto the surface of the second photoconductor drum 11M from the left on the paper, and an electrostatic latent image corresponding to the magenta component is formed. The laser light of the cyan component is irradiated onto the surface of the third photoconductor drum 11C from the left on the paper, and an electrostatic latent image of the cyan component is formed. The laser light of the black component is irradiated onto the surface of the fourth photoconductor drum 11BK from the left on the paper, and an electrostatic latent image of the black component is formed.

Thereafter, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK on which the electrostatic latent images of the respective colors are formed reach positions facing the developing unit 13. Then, the toner of the respective colors is supplied from each developing unit 13 onto the photoconductor drums 11Y, 11M, 11C, and 11BK, and the latent images on the photoconductor drums 11Y, 11M, 11C, and 11BK are developed (this is the developing process).
Thereafter, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK after the development process reach the portions facing the intermediate transfer belt 17. Here, primary transfer bias rollers 14 are provided at each of the facing portions so as to abut against the inner peripheral surface of the intermediate transfer belt 17. Then, at the positions of the primary transfer bias rollers 14, the toner images of each color formed on the photoconductor drums 11Y, 11M, 11C, and 11BK are transferred onto the intermediate transfer belt 17 in order, superimposed thereon (this is the primary transfer process).

After the transfer process, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK each reach a position facing the cleaning unit 15. The cleaning unit 15 then collects untransferred toner remaining on the photoconductor drums 11Y, 11M, 11C, and 11BK (this is the cleaning process).
Thereafter, the surfaces of the photoconductor drums 11Y, 11M, 11C, and 11BK pass through a charge removing section, and a series of image forming processes on the photoconductor drums 11Y, 11M, 11C, and 11BK are completed.

Meanwhile, the intermediate transfer belt 17 onto which the toners of the respective colors on the photoconductor drums 11Y, 11M, 11C, and 11BK are transferred (carried) in an overlapping manner travels in a clockwise direction in the drawing and reaches a position facing the secondary transfer bias roller 18. Then, at the position facing the secondary transfer bias roller 18, the color toner images carried on the intermediate transfer belt 17 are transferred onto the sheet P (secondary transfer process).
Thereafter, the surface of the intermediate transfer belt 17 reaches the position of the intermediate transfer belt cleaning unit 16. Then, the untransferred toner adhering to the intermediate transfer belt 17 is collected by the intermediate transfer belt cleaning unit 16, and a series of transfer processes on the intermediate transfer belt 17 is completed.

Here, the sheet P transported between the intermediate transfer belt 17 and the secondary transfer bias roller 18 (secondary transfer nip) is transported from the paper feed section 7 via the registration rollers 9 and the like.
More specifically, the sheet P fed by a feed roller 8 from a feed unit 7 storing the sheet P passes through a transport guide and is then guided to a registration roller 9. The sheet P that has reached the registration roller 9 is transported in a timely manner toward the secondary transfer nip.

Then, the sheet P onto which the full-color image has been transferred is guided by a conveyor belt to a fixing device 20. In the fixing device 20, the color image (toner image) is fixed onto the sheet P at a fixing nip (nip portion) between a fixing belt 21 and a pressure roller 31 (fixing process).
After the fixing process, the sheet P is discharged by a discharge roller to the outside of the apparatus main body 1 as an output image, and a series of image forming processes (printing operations) is completed.

Next, the configuration and operation of the fixing device 20 as a belt device installed in the image forming apparatus main body 1 will be described in detail with reference to FIG.
As shown in FIG. 2, the fixing device 20 as a belt device is composed of a fixing belt 21 as a belt member, a heating roller 22, a fixing auxiliary roller 23, a tension roller 25, a heater 26 as a heating means, a temperature sensor 40, a pressure roller 31 as a pressure rotating body, and the like.

Here, the fixing belt 21 as a belt member is a fixing rotating body that heats the toner image on the sheet P and fixes it on the sheet P. The fixing belt 21 is an endless belt with a multi-layer structure in which an elastic layer and a release layer (surface layer) are sequentially laminated on a base layer made of a resin material such as polyimide. The elastic layer of the fixing belt 21 is formed of an elastic material such as fluororubber, silicone rubber, and foamed silicone rubber with a layer thickness of about 90 μm. The release layer of the fixing belt 21 is formed of PFA (tetrafluoroethylene perfluoroalkylvinylether copolymer resin), polyimide, polyetherimide, PES (polyether sulfide), or the like with a layer thickness of about 20 μm. By providing a release layer on the surface layer of the fixing belt 21, the releasability (peeling ability) for the toner T (toner image) is ensured. The fixing belt 21 is stretched and supported by three roller members (a heating roller 22, a fixing auxiliary roller 23, and a tension roller 25), and runs (rotates) in the direction of the arrow (clockwise) in FIG. 2. By using the fixing belt 21 having a low heat capacity as the fixing rotation body, the temperature rise characteristic of the device is improved.
In the present embodiment, the three roller members 22, 23, and 25 are used to support and stretch the fixing belt 21, but the number of roller members is not limited to this.

The heating roller 22 is a roller member with a hollow structure made of a metal material such as aluminum or stainless steel, and a heater 26 (heat source) is fixed inside the cylindrical body as a heating means without rotating. By setting the thickness of the heating roller 22 to be relatively thin, the heat capacity of the heating body is reduced and the temperature rise characteristics of the device are improved (the rise time is shortened).

The heater 26 (heating means) provided inside the heating roller 22 is a halogen heater, and both ends thereof are fixed to the side plates of the first frame 41 (see FIG. 3) of the fixing device 20. When the main switch of the image forming apparatus main body 1 is turned on, power is supplied to the heater 26 from a power supply unit (not shown). The heating roller 22 is heated by radiant heat from the heater 26, the output of which is controlled by a control unit, and heat is further applied to the toner image T on the sheet P from the surface of the fixing belt 21 heated by the heating roller 22.
The output control of the heater 26 is performed based on the detection result of the belt surface temperature by a temperature sensor 40 that faces the surface of the fixing belt 21 without making contact with it. More specifically, an AC voltage is applied to the heater 26 for a current-carrying time that is determined based on the detection result of the temperature sensor 40 (thermopile). By controlling the output of the heater 26 in this way, the temperature of the fixing belt 21 (fixing temperature) can be adjusted and controlled to a desired temperature (target control temperature).
In this embodiment, one heater 26 is provided inside the heating roller 22, but a plurality of heaters may be provided.
In this embodiment, the temperature sensor 40 is disposed at a position opposite to the heating roller 22 with the fixing belt 21 interposed therebetween.

The fixing auxiliary roller 23 is a roller member in which an elastic layer made of a foaming material such as foamed silicone rubber is formed on a core metal such as SUS304, and is pressed against the pressure roller 31, which serves as a pressure rotating body, via the fixing belt 21 to form a fixing nip. By forming the elastic layer from a foaming material, the nip width (nip amount) in the fixing nip can be set relatively large, and heat from the fixing belt 21 is less likely to be transferred to the fixing auxiliary roller 23. The fixing auxiliary roller 23 rotates in the clockwise direction in FIG. 2.

The tension roller 25 is disposed downstream (in the belt running direction) of the fixing nip (fixing auxiliary roller 23 ) and upstream of the heating roller 22 so as to abut against the inner surface of the fixing belt 21 .
The tension roller 25 may be biased by a compression spring to apply tension to the fixing belt 21 .

The pressure roller 31 is a pressure rotating body that forms a fixing nip through which the sheet P is conveyed by pressing it against the auxiliary fixing roller 23 via the fixing belt 21. The pressure roller 31 as a pressure rotating body mainly consists of a core 32 made of a metal material, an elastic layer 33 formed on the outer peripheral surface of the core 32 via an adhesive layer, and a surface layer 34 (release layer) formed on the outer peripheral surface of the elastic layer 33. The elastic layer 33 of the pressure roller 31 has a layer thickness of about several mm and is formed of an elastic material such as foamed silicone rubber, fluororubber, or silicone rubber that has insulating properties. The surface layer 34 of the pressure roller 31 has a layer thickness of about several tens of μm to several hundreds of μm and is formed of a low-friction material such as conductive PFA (PFA tube). By providing a conductive release layer as the surface layer 34 of the pressure roller 31, the release property (peelability) for the toner T (toner image) is guaranteed, and the problem of the sheet P being electrostatically attracted to the pressure roller 31 and reducing the separation property can be reduced.

The fixing device 20 configured as above operates as follows.
When the main switch of the apparatus main body 1 is turned on, an AC voltage is applied (power is supplied) from the power supply unit to the heater 26 .
When a print command (job command) is input, the pressure roller 31 is rotated in the direction of the arrow in FIG. 2 by a drive motor (not shown), and the fixing belt 21, the heating roller 22, and the tension roller 25 are rotated in the direction of the arrow in FIG. 2 (clockwise). Then, a sheet P is fed from the paper feed unit 7, and the toner image on the intermediate transfer belt 17 is carried on the sheet P as an unfixed image at the position of the secondary transfer bias roller 18. The sheet P carrying the unfixed image (toner image) is transported in the direction of the dashed arrow in FIG. 2 and is fed into the fixing nip between the fixing belt 21 and the pressure roller 31 in a pressure contact state. Then, the toner image is fixed on the surface of the sheet P by the heating of the fixing belt 21 and the pressing force of the fixing belt 21 (fixing auxiliary roller 23) and the pressure roller 31. Then, the sheet P sent out from the fixing nip by the rotating fixing belt 21 and pressure roller 31 is transported in the direction of the dashed arrow.

The characteristic configuration and operation of the fixing device 20 (image forming apparatus 1) in this embodiment will be described in detail below.
2, 3, etc., the fixing device 20 in this embodiment is a belt device provided with a fixing belt 21 as a belt member stretched around a plurality of roller members (a heating roller 22, a fixing auxiliary roller 23, and a tension roller 25). The fixing device 20 is detachably installed in the image forming apparatus main body 1.
The fixing belt 21 as a belt member is heated by a heater 26 as a heating means, and while traveling in a predetermined traveling direction, heats and fixes the toner image on the sheet P. The fixing device 20 as a belt device is provided with a pressure roller 31 as a pressure rotating body that presses against the fixing belt 21 to form a fixing nip through which the sheet P is transported.

3 to 5, fixing device 20 serving as a belt device in the present embodiment is provided with a first frame 41 (lower frame) and a second frame 42 (upper frame).
The first frame 41 is a part of a housing that holds a plurality of roller members (the heating roller 22, the fixing auxiliary roller 23, and the tension roller 25) and the fixing belt 21 (belt member). The second frame 42 is a part of a housing that is separably combined with the first frame 41.

More specifically, the housing (frame) of the fixing device 20 is configured to be separable into a first frame 41 and a second frame 42. Specifically, Figures 3 and 4 show the first and second frames 41 and 42 in a combined state, and in this combined state, the fixing step (image forming process) described above with reference to Figures 1 and 2 is performed. In contrast, Figure 5 shows the first and second frames 41 and 42 in a separated state (detached state), and in this separated state, maintenance of the fixing device 20 (removed from the image forming apparatus main body 1) is performed.
In the present embodiment, the first and second frames 41 and 42 are each formed in a substantially box-like shape from a metal material, and are each integrated with the exterior of the fixing device 20.

In the present embodiment, the fixing device 20 has the second frame 42, which was in a divided state, combined with the first frame 41, so that the position of one of the roller members 22, 23, 25 (the heating roller 22 with the heater 26 installed therein as a heating means) is regulated in the combined first frame 41 and second frame 42.

More specifically, the first frame 41 is provided with a contact member 51 and a guide portion 41a.
The contact member 51 is configured to be movable in a predetermined direction while contacting the heating roller 22 (one roller member). In this embodiment, the contact member 51 is made of a resin material having high rigidity and heat resistance, and is held relatively loosely in a recess formed in the first frame 41 at a position facing the heating roller 22 so as to be movable in the directions of the double arrows in FIG.
The guide portions 41a guide the movement of the heating roller 22 (one roller member) in a predetermined direction (the direction of the double arrow in Figure 3), and are formed in opposing positions on the first frame 41 so as to sandwich the heating roller 22.
The heating roller 22 is disposed so as to be in contact with the guide portion 41 a and the contact member 51 on three sides.
The first frame 41 is provided with the fixing belt 21, the heating roller 22, the fixing auxiliary roller 23, the tension roller 25, as well as the pressure roller 31 and a transport path along which the sheet P is transported.

In contrast, the second frame 42 is provided with a pushing member 52 that pushes the heating roller 22 (one roller member) toward the second frame 42 in conjunction with the operation of combining with the first frame 41 (the operation of transitioning from the state in FIG. 5 to the state in FIG. 3). Furthermore, the second frame 42 is provided with a compression spring 53 as a biasing member that biases the pushing member 52 toward the heating roller 22.
As shown in FIG. 5, when the second frame 42 is separated, main members such as the fixing belt 21 are exposed in the first frame 41.

Then, referring to Figure 3, the position of the heating roller 22 (one roller member) is determined in the combined first frame 41 and second frame 42 at the position after the pressing member 52 presses the heating roller 22 (one roller member) and the abutment member 51 moves in a predetermined direction (diagonally downward to the right in Figure 3).
Specifically, in the combined state, the pressing force of the pressing member 52 (the biasing force of the compression spring 53) causes the abutting member 51 to abut against the bottom of the recess in the first frame 41 via the heating roller 22, and the position of the heating roller 22 in the first and second frames 41, 42 is determined. That is, the heating roller 22 is restricted on all four sides by the pressing member 52, the abutting member 51, and the guide portion 41a.
In this way, in the first and second frames 41, 42, the position of the heating roller 22, which serves as one of the multiple roller members 22, 23, 25 that stretch and support the fixing belt 21, is regulated, so that the position of the fixing belt 21 is determined with high precision.

As shown in Fig. 4, the contact member 51 (and the guide portion 41a) and the pressing member 52 are provided on both sides in the width direction (the left-right direction in Fig. 4, which is the direction perpendicular to the paper surface of Fig. 3, etc.). The contact member 51 (and the guide portion 41a) and the pressing member 52 are provided at positions outside (non-paper passing area) of the paper passing area M (the width direction range through which the sheet P passes in the fixing device 20). Furthermore, the contact member 51 (and the guide portion 41a) and the pressing member 52 are formed in shapes and positions that do not hinder the operation of other components such as the fixing belt 21, the fixing auxiliary roller 23, the tension roller 25, and the pressure roller 31.
With this configuration, the heating roller 22 is positioned in a well-balanced manner on the first and second frames 41 and 42, and the fixing process is performed smoothly by the fixing device 20 without any problems.

In this manner, in the fixing device 20 according to the present embodiment, the second frame 42 is separable from the first frame 41 that holds the main components such as the fixing belt 21, and therefore the maintenance of the main components such as the fixing belt 21 can be easily performed. In other words, the maintainability of the fixing device 20 is improved. In particular, since the contact member 51 is movably installed on the first frame 41, the maintainability of the fixing belt 21 is improved compared to the case where the contact member 51 is fixedly installed on the first frame 41.
The first and second frames 41, 42 are configured to be separable, and when the separated first and second frames 41, 42 are moved to a combined state, the position of the heating roller 22, which is one of the roller members that stretch and support the fixing belt 21, is determined. Therefore, the posture of the fixing belt 21 can be determined with high accuracy in the combined first and second frames 41, 42. This allows the fixing device 20 to perform the fixing process well.

Here, as shown in FIG. 3 etc., the fixing device 20 in this embodiment is set so that the direction in which the pressing member 52 presses the heating roller 22 (one roller member) coincides with a predetermined direction (the direction in which the abutment member 51 moves).
That is, the pushing direction of the pushing member 52 and the moving direction of the abutting member 51 are set to be the same direction.
With this configuration, the position of the heat roller 22 can be determined efficiently and accurately by the contact member 51 (and the guide portion 41 a ) and the pushing member 52 .

In this embodiment, a rigid body that can move in a predetermined direction (the direction of the double-headed arrow in Figure 3) is used as the abutment member 51, but an elastic body that can deform in a predetermined direction (the direction of the double-headed arrow in Figure 3) may also be used.
In this case, in the combined state, the position of the heating roller 22 in the first and second frames 41, 42 is determined at the position after the heating roller 22 (one roller member) is pushed by the pushing member 52 and the abutment member 51 is deformed in a predetermined direction.
Even in such a case, ease of maintenance of the fixing device 20 and highly accurate positioning of the fixing belt 21 can be achieved at the same time.

<Modification 1>
As shown in FIG. 6, in the fixing device 20 (belt device) of the first modification, a second compression spring 55 (second biasing member) is provided on the first frame 41 to bias the contact member 51 toward the heating roller 22.
When configured in this manner, in the combined first and second frames 41, 42, the position of the heating roller 22 is determined by the position after the heating roller 22 is pushed by the pushing member 52 and the abutting member 51 moves in a predetermined direction (diagonally downward to the right in Figure 6) against the biasing force of the second compression spring 55.
Even when configured in this manner, the position of the heating roller 22, which serves as one of the multiple roller members 22, 23, 25 that stretch and support the fixing belt 21, is regulated in the first and second frames 41, 42, thereby enabling the position of the fixing belt 21 to be determined with high precision.

<Modification 2>
As shown in FIG. 7, a fixing device 20 (belt device) in the second modification is configured such that a second frame 42 is rotatable in the direction of the double arrow with respect to a first frame 41 about a support shaft 41x.
Note that Figure 7 shows a state in which the second frame 42 rotates clockwise around the support axis 41x relative to the first frame 41, opening the interior surrounded by the first and second frames 41, 42 and separating the first and second frames 41, 42.
Even when configured in this manner, when the first and second frames 41, 42 transition from an open state (split state) to a closed state (combined state), the position of the heating roller 22, which is one of the multiple roller members 22, 23, 25 that stretch and support the fixing belt 21, is regulated, and the position of the fixing belt 21 is determined with high precision.

As described above, the fixing device 20 (belt device) in this embodiment includes the fixing belt 21 (belt member) stretched around the plurality of roller members 22, 23, and 25, the first frame 41 that holds the plurality of roller members 22, 23, and 25 and the fixing belt 21, and the second frame 42 that is separably combined with the first frame 41. The second frame 42, which was in a separated state, is combined with the first frame 41, so that the position of the heating roller 22 (one roller member) among the plurality of roller members 22, 23, and 25 is regulated in the combined first frame 41 and second frame 42.
This makes it easier to accurately determine the posture of the fixing belt 21 in the combined first and second frames 41, 42, even if the second frame 42 is configured to be separable from the first frame 41 which holds the fixing belt 21 and the multiple roller members 22, 23, and 25.

In this embodiment, the pressure roller 31 (roller member) is used as the pressure rotating body, but a pressure belt (belt member) can also be used as the pressure rotating body. In that case, the first and second frames can be configured to transition from a divided state to a combined state so that the position of one of the roller members stretching the pressure belt is regulated.
In addition, in this embodiment, the present invention is applied to a fixing device 20 of a thermal heater type that uses a heater 26 as a heating means, but the application of the present invention is not limited to this, and the present invention can also be applied, for example, to a fixing device of an electromagnetic induction type (IH type) that uses an electromagnetic induction coil as a heating means, or a fixing device of a resistance heating type that uses a resistance heating element as a heating means.
In this embodiment, a non-rotating, fixed pad (nip forming member) may be used in place of the fixing auxiliary roller 23 .
In addition, in this embodiment, the abutment member 51 and the pushing member 52 are configured to directly abut against the outer peripheral surface of the roller portion of the heating roller 22, but they can also be configured to directly abut against the outer peripheral surface of the shaft portion of the heating roller 22, or to indirectly abut against the heating roller 22 via another member.
In these cases, the same effects as those of the present embodiment can be obtained.

In addition, in this embodiment, the first and second frames 41, 42 are configured to transition from a divided state to a combined state, thereby restricting the position of the heating roller 22 among the multiple roller members 22, 23, 25 that stretch the fixing belt 21, but the roller member whose position is restricted in this manner is not limited to the heating roller 22, and it is also possible to restrict the position of the tension roller 25, for example. However, when the position of the heating roller 22 arranged closest to the upstream side of the fixing nip in the belt running direction among the multiple roller members 22, 23, 25 is restricted, a better fixing process can be performed compared to when the positions of the roller members arranged in other positions are restricted.
In addition, in this embodiment, the present invention is applied to the fixing device 20 as a belt device, but the belt device to which the present invention is applied is not limited to this, and the present invention can also be applied to, for example, an intermediate transfer belt device in which an intermediate transfer belt 17 is installed.
In these cases, the same effects as those of the present embodiment can be obtained.

It is clear that the present invention is not limited to this embodiment, and that within the scope of the technical concept of the present invention, this embodiment may be modified as appropriate in ways other than those suggested in this embodiment. Furthermore, the number, position, shape, etc. of the components are not limited to this embodiment, and may be any number, position, shape, etc. that is suitable for implementing the present invention.

In this specification, the term "sheet" is not limited to paper, but is defined to include all sheet-like recording media, such as coated paper, label paper, and OHP sheets.
In addition, in this specification, the "split state" of the first and second frames is defined to include not only a state in which the first and second frames are completely separated, as shown in Figure 5, but also a state in which the second frame is opened relative to the first frame, and the interior surrounded by the first and second frames is open, as shown in Figure 7.

1 Image forming apparatus (image forming apparatus main body),
20 Fixing device (belt device),
21 Fixing belt (belt member),
22 heating roller (one roller member),
26 heater (heating means),
31 Pressure roller (pressure rotating body),
41 first frame,
41a guide portion,
42 second frame,
51 abutment member,
52 Pushing member,
53 compression spring (biasing member),
55 Second compression spring (second biasing member),
P sheet (recording medium).

In addition, the present invention can also be embodied in a combination of Supplementary Notes 1 to 7 as follows.
(Appendix 1)
A belt member stretched around a plurality of roller members;
a first frame that holds the roller members and the belt member;
a second frame that is divisibly combined with the first frame;
Equipped with
A belt device characterized in that the position of one of the plurality of roller members is regulated in the combined first and second frames by combining the second frame, which was in a separated state, with the first frame.
(Appendix 2)
The first frame is
a contact member that is in contact with the one roller member and is movable or deformable in a predetermined direction;
a guide portion that guides the movement of the one roller member in the predetermined direction;
Equipped with
2. The belt device according to claim 1, wherein the second frame includes a pushing member that pushes the one roller member toward the second frame in response to an operation of combining with the first frame.
(Appendix 3)
3. The belt device according to claim 2, wherein a direction in which the one roller member is pushed by the pushing member coincides with the predetermined direction.
(Appendix 4)
The belt device according to claim 2 or 3, characterized in that the position of the one roller member in the combined first frame and second frame is determined at a position after the one roller member is pushed by the pushing member and the abutment member moves or deforms in the predetermined direction.
(Appendix 5)
A fixing device as a belt device according to any one of claims 1 to 4,
a fixing belt as the belt member that is heated by a heating means and heats and fixes a toner image on a sheet while traveling in a predetermined traveling direction;
a pressure rotating member that forms a fixing nip through which a sheet is conveyed by being pressed against the fixing belt;
A fixing device comprising:
(Appendix 6)
6. The fixing device according to claim 5, wherein the one roller member is a heating roller having a heater disposed therein as the heating means.
(Appendix 7)
5. An image forming apparatus comprising the belt device according to claim 1.

JP 2009-288264 A

Claims (7)

A belt member stretched around a plurality of roller members;
a first frame that holds the roller members and the belt member;
a second frame that is divisibly combined with the first frame;
Equipped with
A belt device characterized in that the position of one of the plurality of roller members is regulated in the combined first and second frames by combining the second frame, which was in a separated state, with the first frame. The first frame is
a contact member that is in contact with the one roller member and is movable or deformable in a predetermined direction;
a guide portion that guides the movement of the one roller member in the predetermined direction;
Equipped with
2. The belt device according to claim 1, wherein the second frame includes a pressing member that presses the one roller member toward the second frame in conjunction with an operation of combining with the first frame. The belt device according to claim 2, characterized in that the direction in which the pushing member pushes the one roller member coincides with the predetermined direction. The belt device according to claim 2 or 3, characterized in that the position of the one roller member is determined in the combined first frame and second frame at a position after the one roller member is pushed by the pushing member and the contact member moves or deforms in the predetermined direction. 3. The fixing device as the belt device according to claim 1,
a fixing belt as the belt member that is heated by a heating means and heats and fixes a toner image on a sheet while traveling in a predetermined traveling direction;
a pressure rotating member that is in pressure contact with the fixing belt to form a fixing nip through which a sheet is conveyed;
A fixing device comprising: The fixing device according to claim 5, characterized in that the one roller member is a heating roller having a heater built therein as the heating means. An image forming apparatus comprising the belt device according to claim 1 or 2.

Images