JP2004117805A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which has a high cost merit by reducing a cost of a fixing unit. <P>SOLUTION: The image forming apparatus uses the fixing unit for fixing a sheet carrying an unfixed image by a heater while the sheet is passed between a rotatable fixing rotor and a pressurizing rotor pressure set to each other. In this apparatus, a stay for coupling information between opposed side plates for supporting the fixing rotor or the pressurizing rotor is formed of a resin material. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus such as a printer for a computer, a copying machine, and a facsimile.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an image forming apparatus using an electrophotographic method forms, for example, an electrostatic latent image on a surface of a photosensitive drum as an image carrier, and develops the electrostatic latent image on the photosensitive drum with toner or the like as a developer. Then, the developed image is transferred to a transfer material by a transfer device to carry the image on the transfer material, and the toner image on the transfer material is fixed by a fixing device using pressure, heat, or the like. The transferred transfer material is discharged out of the apparatus through a paper discharge path. In the fixing device, a heater and a pressure roller as fixing means are arranged. The toner image transferred sheet that has reached the fixing device enters the fixing nip of the heater and the pressure roller. While the sheet passes through the fixing nip, the transferred toner image is heated and pressed to be fixed on the sheet surface.
[0003]
Further, since the life of components such as the pressure roller of the fixing device is shorter than the life of the device main body, the fixing device is often configured as a fixing unit detachable from the device main body. Further, in order to facilitate a user's jam clearance in the vicinity of the fixing nip, the fixing device is often configured as a fixing unit detachable from the apparatus main body.
[0004]
Here, as shown in FIG. 8, a pressure of about 15 kgf is applied between the heater and the pressure roller 6 by the pressure spring 22, and the opposite side plate supporting the pressure roller is easily distorted. The upper part between the side plates is connected by a metal reinforcing stay 50. Since the stay is located above the heater, the stay becomes hot to about 90 ° C., and if the user touches the fixing device when attaching or detaching the fixing device, the stay may be burned.
[0005]
[Problems to be solved by the invention]
Therefore, in this type of image forming apparatus, a metal stay for connecting the side plates for reinforcement and a resin for protecting the user are provided above the opposed side plates that support the fixing rotator or the pressing rotator. There is a problem that the cost of the fixing device increases due to the presence of the two parts of the cover.
[0006]
Accordingly, it is an object of the present invention to provide an image forming apparatus which reduces the cost of a fixing device and has a high cost merit.
[0007]
[Means for Solving the Problems]
The above object is achieved by an image forming apparatus according to the present invention. The present invention is directed to an image using a fixing device in which a heating body performs a fixing process on a sheet carrying an unfixed image while passing the sheet between a fixing rotator and a pressure rotator that are pressed against each other and are rotatable. In the forming apparatus, a stay that connects an upper portion between opposed side plates that support the fixing rotating body or the pressing rotating body is formed of a resin material.
[0008]
According to the first aspect of the present invention, a metal reinforcing stay for connecting the upper side between the opposing side plates supporting the fixing rotator or the pressure rotator and the upper part of the fixing device for user protection are covered. By forming the two parts of the resin cover with one stay made of a resin material, the cost of the fixing device can be reduced.
[0009]
According to the second aspect of the present invention, since the stay formed of the resin material has a channel structure extending in the connecting direction, it is possible to connect the upper portion between the opposed side plates supporting the fixing rotating body or the pressing rotating body. Strength as a reinforcing stay is increased.
[0010]
According to the third aspect of the invention, since the stay formed of the resin material has a shape that covers a part of the side surface, the back surface, or the front surface of the fixing device, a new component for protecting the user is not required, and the fixing device is not required. Cost can be prevented.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
First, the overall configuration of the image forming apparatus will be briefly described with reference to FIG. When a print start signal is input, the laser scanner 30 irradiates a laser beam corresponding to image information onto the photosensitive drum 31 rotating clockwise. As a result, an electrostatic latent image is formed on the photosensitive drum 31, and the electrostatic latent image is developed with toner by a developing device (not shown).
[0012]
When the print start signal is input, the sheets S stacked and stored in the cassette 32 are sequentially fed out from the top sheet by the sheet feed roller 33 rotating in the counterclockwise direction. The fed sheet S is sent to the registration roller pair 35 in the rotation stopped state by the conveyance roller pair 34.
[0013]
The sheet S sent to the registration roller pair 35 stops moving when a predetermined amount of loop is formed by the leading end of the sheet abutting the nip of the registration roller pair 35. By forming this loop, the skew state of the sheet S is corrected.
[0014]
The sheet S whose skew has been corrected is sent to a transfer portion between the photosensitive drum 31 and the transfer roller 36 by a pair of registration rollers 35 that starts rotating at a predetermined timing with respect to the toner image on the photosensitive drum 31. . The toner image on the photosensitive drum 31 is transferred to the sheet S passing through the transfer section by the transfer roller 36.
[0015]
The sheet S to which the toner image has been transferred after passing through the transfer unit is sent to the on-demand type fixing unit 1. Then, the toner image being transferred is fixed on the sheet surface by being heated and pressed in the course of passing through the fixing unit 1. The sheet S that has undergone the fixing process that has passed through the fixing device 1 is discharged to the face down tray 4 by the discharge roller 3 via the intermediate conveyance roller 2.
[0016]
Here, the fixing unit 1 of the on-demand system will be described with reference to FIG. A heater 5 and a pressure roller 6 as a fixing unit, and a conveying roller pair 7 are arranged in this order from the upstream side in the sheet conveying direction.
[0017]
The heater 5 has a plate shape. The plate-shaped heater 5 is fixed to a flat portion (a portion facing the pressure roller 6) of a film guide 9 for guiding rotation (inner surface guide) of the cylindrical fixing film 8. I have. The film guide 9 is fixed at a predetermined position.
[0018]
The pressure roller 6 is fixed at a position facing the heater 5. Drive from a main motor (not shown) is transmitted to the pressure roller 6, and the pressure roller 6 rotates counterclockwise. The cylindrical fixing film 8 is rotated by the rotation of the pressure roller 6 while being guided by the film guide 9.
[0019]
The toner image transferred sheet S that has reached the fixing unit 1 is guided by the guide 10 and enters the fixing nip of the heater 5 and the pressure roller 6. While the sheet S passes through the fixing nip, the transferred toner image is heated and pressed, and is fixed on the sheet surface. The sheet S that has passed through the fixing nip enters the transport nip of the transport roller pair (transport unit) 7. The sheet S that has been subjected to the fixing process and discharged by the pair of conveying rollers 7 is sent to the face down tray 4 while being guided by the conveying guide (rib) 37.
[0020]
Next, the configuration of a characteristic portion of the present invention will be described with reference to FIGS.
[0021]
FIG. 3 and FIG. 4 are perspective views of the fixing unit 1. The fixing unit 1 is configured to be detachable from the apparatus main body as shown in FIG. 5, and can be detached from the main body by operating the lock lever 40 in FIG.
[0022]
6 and 7 show only the characteristic portions of the present invention and omit other portions. In FIG. 6, reference numeral 20 denotes a fixing frame (sheet metal), and the pressure roller 6 is rotatably supported on a side plate 20 a of the fixing frame via a bearing 21. Further, a pressure of 15 kgf is applied between the heating heater, the fixing film 8 and the pressure roller 6 by the pressure spring 22. An upper fixing cover 23 is fixed to upper portions 20b and 20c of the fixing frame 20 with screws to correct a distance between side plates and the like.
[0023]
The fixing upper cover 23 is formed of PET (containing glass) having heat-resistant and high-rigidity characteristics, has a channel structure extending in the connection direction as shown in FIG. 7A, and is provided with a reinforcing rib 23a. It has sufficient rigidity as a reinforcement stay. The fixing upper cover 23b, 23c, 23d has a shape that covers a part of the side surface and the rear surface of the fixing device, so that the user does not directly touch the fixing frame 20 to prevent a burn or the like. .
[0024]
【The invention's effect】
An image forming apparatus using a fixing device in which a heating element performs a fixing process on the sheet while passing a sheet carrying an unfixed image between a rotatable fixing rotator and a rotatable pressing rotator that are pressed against each other, A stay for connecting the upper side between opposed side plates supporting the fixing rotating body or the pressure rotating body is formed of a resin material.
[0025]
Therefore, two parts, a metal reinforcing stay for connecting the upper side between the opposing side plates supporting the fixing rotator or the pressing rotator, and a resin cover covering the upper part of the fixing device for user protection, are made of a resin material. Therefore, the fixing device can be made up of one part, and the cost of the fixing device can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus according to a first embodiment.
FIG. 2 is a detailed view of a fixing unit. FIG. 3 is a detailed view of an embodiment. FIG. 4 is a detailed view of an embodiment. FIG. 5 is a detailed view of an embodiment. FIG. 6 is a detailed view of an embodiment. FIG. 8 is a detailed diagram of an example.
1: Fixing unit 6: Pressure roller 20: Fixing frame 20a: Side plate 23 of fixing frame: Fixing upper cover

Claims (5)

In an image forming apparatus using a fixing device in which a heating element performs a fixing process on the sheet while a sheet carrying an unfixed image is passed between a rotatable fixing rotator and a pressure rotator that are pressed against each other and are rotatable,
A pair of side plates that support the fixing rotator or the pressure rotator,
An image forming apparatus, wherein a member connecting the side plates on the image carrying surface side of the side plate is formed of a resin material. The image forming apparatus according to claim 1, wherein the connecting member has a channel structure extending in a connecting direction. The image forming apparatus according to claim 1, wherein the connecting member has a shape that covers a part of a side surface, a back surface, or a front surface of the fixing device. 4. The image forming apparatus according to claim 1, wherein the resin material of the connecting member is PET. The image forming apparatus according to claim 1, wherein the fixing device is configured as a unit detachable from an apparatus main body.

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