JPH07295459A - Image forming apparatus - Google Patents

Abstract

PURPOSE:To provide an image forming apparatus in which a fixing unit can be positioned surely in a main body part without being accompanied with any trouble such as vibration, etc., after setting and without increasing the number of parts by composing the image forming apparatus in the way wherein a process unit is changed by opening the upper part of an apparatus box. CONSTITUTION:An axial pin 9 of a fixing unit 8 is so made as to be positioned to a main body frame 13 and the joining of the pin 9 with the axial pin of a link lever 11 attached to the main body frame 13 is made possible to be released by releasing operation of a lock lever 10 attached to an upper part opening and closing cover 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying machine or a facsimile, and more particularly to an image forming apparatus of the type in which a process unit is replaced by rotating and opening an upper part of an apparatus casing.

[0002]

2. Description of the Related Art When a so-called consumable item such as a developing toner contained in an image forming apparatus or a process unit integrating a photosensitive member and a developing apparatus is replaced, a door provided in an apparatus casing. Etc. are opened and work is performed. Conventionally, there are two types of opening of the housing. That is,
The work is performed with the front surface of the housing open, and the work with the top of the housing opened.

In most downsized image forming apparatuses, most of them are replaced by opening the upper part of the housing. In such an apparatus of the case upper opening type, since opening and closing only the case portion is not sufficient for securing a working space, the fixing system is opened and closed among units related to image information formation. It is attached to the housing so that the open space is wider when the upper part of the housing is opened.

At this time, various proposals have been made to ensure a highly accurate image quality for a fixed image formed by transferring and fixing image information on a sheet. For example, in Japanese Unexamined Patent Publication No. 3-48259, one of an image carrier as an image forming unit and a pair of registration rollers is positioned by a bearing of a main body frame, and a fixing unit faces the sheet conveying path in a closed state on the opening / closing body side. A configuration is disclosed in which image forming means such as a container, a transfer roller, and the other of a pair of registration rollers are sequentially arranged from above, which makes it possible to accurately position the registration roller with respect to the axis of the image carrier during operation. The fixing device is also accurately positioned with respect to the image forming unit, and it is always possible to obtain a highly accurate image.

[0005]

However, in the structure in which one of the fixing unit and the registration roller is held in the opening / closing frame as described above, it is necessary to accurately assemble the fixing unit and the like in the opening / closing frame and to It is necessary to increase the dimensional accuracy and the mounting accuracy, which causes an increase in assembly cost.

As another configuration, in the case where the fixing unit is held by the opening / closing frame and the sheet feeding section, the image forming section, and the optical section are positioned and held by the fixed body frame, the image forming section of the body frame is used. In order to accurately position the fixing unit, the opening / closing frame allows the fixing unit to float, and when the opening / closing frame is closed, the fixing unit is positioned on a part of the main body frame.

However, an additional component such as a spring is required to float the fixing unit, which is a factor of cost increase. Further, the floating causes vibrations generated in the fixing unit itself and vibrations generated from the main body. Therefore, there was a problem that the position of the fixing unit was difficult to stabilize.

Therefore, the present invention is an image forming apparatus in which the upper part of the apparatus casing is opened and closed to replace the process unit, etc., and the number of parts is not increased, and problems such as vibration do not occur after setting. Another object of the present invention is to provide an image forming apparatus capable of reliably positioning the fixing unit with respect to the main body.

[0009]

According to the present invention, an object of the present invention is to provide an image forming apparatus having an upper opening / closing cover to which a fixing unit is attached so that a shaft pin of the fixing unit is positioned with respect to a main body frame. Has become
This is solved by activating the lock lever attached to the upper opening / closing cover to release the engagement of the link lever attached to the main body frame with the shaft pin.

The lock lever has an inclined surface, and when the lock lever is released, the inclined surface slides on the link lever to forcibly release the engagement of the lever with the shaft pin. Is suitable.

[0011]

The details of the present invention will be described below with reference to the embodiments shown in the drawings.

In FIG. 1 showing a laser printer according to the present invention, a sheet picked up from a sheet feeding cassette 1 by a sheet feeding roller 2 or a sheet fed through a manual sheet feeding roller 3 is registered by a registration roller 4. After being timed, the sheet is conveyed to the image forming unit. In the image forming unit 5 as a kit, a charging charger, a developing device, a cleaning device and the like are arranged around the photoconductor.
In this image forming kit, a photoconductor uniformly charged by a charging charger is exposed by an optical unit 7 which is inputted with image information and subjected to predetermined processing, and a latent image formed is visualized by a developing device. Then, the toner image is transferred onto the sheet of paper by the transfer device 6, and is heated and pressed by the fixing unit 8 to fix the image. The image-fixed sheet is discharged onto the main body cover 14 via the sheet discharge roller 12.

As described above, the apparatus housing for accommodating the apparatus for performing the image forming operation as in the conventional case includes the main body cover 14 having the main body frame 13 and the rotary shaft 16 of the manual paper feed roller 3.
And an opening / closing cover 15 which rotates in the direction of arrow A. A fixing unit 8, a lock lever 10, and a paper discharge roller 12 are attached to the open / close cover 15.

The heating roller shaft pin 9 of the fixing unit 8 is provided in a positioning groove formed in the main body frame 13 (side plate) for positioning and holding the image forming portion 5, the transfer device 6, the optical unit 7, and the paper feed rollers 2 and 3. It is fitted. This shaft pin 9
Further, the link lever 11 is engaged with. Engagement of the link lever 11 with the shaft pin 9 is performed by the link spring 1
It is in a pressed state by 7.

2 to 4 show how the cover 15 is opened and then closed again from the closed state of the open / close cover 15 shown in FIG.

In FIG. 2, when the unlocking operation of the lock lever 10 is performed, the lever is rotated around the fulcrum pin 18 in the B direction, that is, in the clockwise direction in the figure, and the tip end inclined surface thereof is the link lever 11. It hits the projection pin 19 of. This contact causes the link lever 11 to move to the link spring 1
The fulcrum pin 20 is pivotally displaced in the clockwise direction against 7, and as a result, the engagement of the lever 11 with the shaft pin 9 is released, and the link lever 11 moves to a position retracted from the shaft pin 9. .

The opening / closing cover 15 can be opened by retracting the link lever 11, and when the cover is opened manually, the state shown in FIG. 3 is obtained. In this open state, the process kit is replaced and jams are processed.
The link lever 11, which is once pushed down by the lock lever, rotates in the C direction around the fulcrum pin 20 due to the acting force of the link spring 17, but contacts the regulation pin 21 attached to the side plate of the main body frame and Movement is regulated.

When the opening / closing cover 15 is closed again, as shown in FIG. 4, the shaft pin 9 of the fixing unit 8 first comes into contact with the tip inclined portion of the link lever 11, and the link spring 1
Against 7, the lever is pushed down in the D direction around the fulcrum pin 20. When the opening / closing cover 15 is further closed, the shaft pin 9 slides on the tip inclined portion of the link lever 11, fits into the positioning groove of the side plate of the main body frame 13, and returns to the state of FIG.

[0019]

According to the image forming apparatus of the present invention, the shaft pin of the fixing unit is positioned with respect to the main body frame, and the main body is released by releasing the lock lever attached to the upper opening / closing cover. Since the link lever attached to the frame is configured to be disengaged from the shaft pin, the fixing unit is positioned and engaged integrally, so that the number of parts and the cost can be reduced. At the same time, after fixing the fixing unit to the main body, problems such as vibration do not occur.

According to another aspect of the image forming apparatus of the present invention, the lock lever has an inclined surface, and when the lock lever is released, the inclined surface slides on the link lever so that the lever is engaged with the shaft pin. Since it is forced to solve,
The open / close cover can be locked / unlocked smoothly and reliably.

[Brief description of drawings]

FIG. 1 is a schematic end view showing a configuration according to an embodiment of the present invention.

FIG. 2 is a schematic diagram corresponding to FIG. 1 when a lock lever is released.

FIG. 3 is a schematic view of the opening / closing cover corresponding to FIG. 1 when the cover is open.

FIG. 4 is a schematic view when closing the opening / closing lever again.

[Explanation of symbols]

 8 Fixing Unit 9 Axis Pin 10 Lock Lever 11 Link Lever 12 Paper Ejection Roller 13 Body Frame 14 Body Cover 15 Open / Close Cover 17 Link Spring

Claims (2)

[Claims] 1. An image forming apparatus having an upper opening / closing cover to which a fixing unit is attached, wherein a shaft pin of the fixing unit is positioned with respect to a main body frame, and a lock lever attached to the upper opening / closing cover. The device is configured to release the engagement of the link lever attached to the main body frame with the shaft pin by the releasing operation of. 2. The lock lever has an inclined surface, and when the lock lever is released, the inclined surface slides with a link lever to forcibly release the engagement of the lever with the shaft pin. The image forming apparatus according to claim 1.