JPH0772757A - Image forming device - Google Patents

Abstract

PURPOSE:To easily remove the recording medium jammed and to satisfactorily miniaturize a device. CONSTITUTION:An image forming device is provided with a photorespector drum 3 for forming the image by transferring the image to the recording medium, an electrifier 4, a developing device 5 and a transferring device 6, and the photosensitive drum 3, the electrifier 4 and the developing device 5 are integrated into one body as the process unit, and the process unit is arranged freely attachably and detachably to and from the device main body 1. The fixing unit 13 is provided for fixing the image of the recording medium by arranging the fixing roller 14 in press contact with the pressure roller 15 and passing the recording medium formed with the image through the press- contacting part of the respective rollers 14 and 15, and the operation part is provided for releasing the press-contact state of the fixing roller 14 and the pressure roller 15 of the fixing unit 13. The lever 16 is provided for normally fixing the process unit to the device main body 1, and releasing the fixation of the process unit to the device main body 1, according to the releasing operation for each of the rollers by the operation part.

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 applied to an electrophotographic apparatus used in a copying machine, a laser printer or the like.

[0002]

2. Description of the Related Art An image forming apparatus of this type is provided with a photosensitive drum, and a charging device, an exposure device such as a laser scanner unit, a developing device, a transfer device and the like are arranged around the photosensitive drum. For image formation, the surface of the photoconductor is uniformly charged by a charging device, and then exposed by an exposure device to record image information on the surface of the photoconductor as an electrostatic latent image, and the electrostatic latent image is developed by a developing device. It is visualized with an agent (toner), and the visualized image is transferred onto a recording paper by a transfer device. Then, the recording paper on which the visualized image is transferred is thermally fixed by the fixing unit and discharged.

In such an image forming apparatus, maintenance such as replacement of the photosensitive drum, disposal of waste toner, replenishment of developer, cleaning of the charging device, etc. is required depending on the period of use.
These maintenance tasks were not normally performed on the user side, but in recent years, small personal type copiers and printers have been developed, and maintenance tasks that are simplified on the user side are required. .

Under the circumstances described above, a series of developing processes such as a charging device, a photosensitive drum, a cleaner, etc. are unitized to be attachable to and detachable from the main body of the apparatus to facilitate maintenance work. The process unit is attached to and detached from the apparatus body by opening and closing the cover of the apparatus body.

Further, the fixing unit is provided with a fixing roller having a heater and a pressure roller which comes into pressure contact with the fixing roller from below, and thermal fixing is carried out by passing the recording paper on which the visualized image is transferred through the pressure contact portion of each roller. When a paper jam problem occurs due to skew of the recording paper or winding of the recording paper around the fixing roller, it is necessary to release the pressure contact state between the fixing roller and the pressure roller in order to pull out the recording paper from the fixing unit. Therefore, a lever is provided and, for example, the pressure roller is pushed down by manually operating the lever, or the pressure roller is pushed down by interlocking the lever with the opening of the cover of the apparatus main body.

[0006]

As described above, conventionally, since the process unit is fixed to the apparatus main body and the pressure contact state between the fixing roller and the pressure roller is released by using separate mechanisms, For example, when a paper jam occurs in the fixing unit, the fixing of the process unit to the apparatus main body is released, the cover is opened, and then the pressure contact state between the fixing roller and the pressure roller is released.
The work was troublesome. Further, since the fixing mechanism and the releasing mechanism are individually incorporated in the main body of the apparatus, the size of the entire apparatus cannot be sufficiently reduced.

Therefore, the present invention provides an image forming apparatus in which the removal operation when the recording medium is jammed is facilitated and the size can be sufficiently reduced.

[0008]

The present invention is provided with a process unit integrally having a part or all of image forming means for transferring and forming an image on a recording medium, and the process unit with respect to the apparatus main body. In a detachable image forming apparatus, a fixing roller and a pressure roller are arranged in pressure contact with each other, and a fixing unit for fixing an image on a recording medium by passing a recording medium on which an image is formed through a pressure contact portion of each roller, Equipped with an operation unit that releases the pressure contact state between the fixing roller and the pressure roller of the fixing unit, the process unit is always fixed to the device body, and the release of each roller by the operation unit releases the fixation of the process unit to the device body. The releasing means is provided.

[0009]

In the present invention having such a structure, the releasing means always fixes the process unit to the apparatus main body. When the operation section releases the pressure contact state between the fixing roller and the pressure roller of the fixing unit, the releasing means simultaneously releases the fixation of the process unit to the apparatus main body.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, 1 is an image forming apparatus main body, 2
Is a cover of the apparatus main body 1.

A photosensitive drum 3 is arranged in the central portion of the apparatus main body 1, and a charging device 4, a developing device 5 and a transfer device 6 which are sequentially composed of a scorotron charger are arranged around the photosensitive drum 3 in a clockwise direction. The image forming means is arranged in the.

For example, a laser scanner unit 7 is arranged as an exposure device in the cover 2 above the developing device 5, and a laser beam 7a from the laser scanner unit 7 is arranged.
Is irradiated onto the surface of the photosensitive drum 3 through a space between the charging device 4 and the developing device 5.

The developing device 5 comprises a container 9 containing the developer 8, a developing roller 10 for supplying the developer 8 in the container 9 to the surface of the photosensitive drum 3, and the like.

Of the image forming means, the photosensitive drum 3, the charging device 4 and the developing device 5 are unitized as a process unit and housed inside the cover 2, and can be detached from the main body 1 by opening the cover 2. It is like this. Further, this process unit can be pulled out obliquely upward in the drawing when it is separated from the apparatus main body 1 by opening the cover 2.

A paper tray 11 for supplying recording paper, which is a recording medium, is arranged on one end side of the apparatus main body 1, and the recording paper supplied by the paper tray 11 is fed by the paper feed roller 1.
2, the transfer portion, that is, the photosensitive drum 3 and the transfer device 6
It is designed to be conveyed to a portion facing the.

The photosensitive drum 3 rotates clockwise in the figure, and the charging device 4 uniformly charges the surface of the photosensitive drum 3. Laser light 7a from the laser scanner unit 7
Exposes the surface of the uniformly charged photosensitive drum 3 to record image information as an electrostatic latent image. The developing device 5 supplies the developer 8 to the electrostatic latent image on the surface of the photosensitive drum to visualize it.
The transfer device 6 transfers the visualized image on the surface of the photoconductor drum onto a recording paper sheet to be conveyed.

The recording paper on which the visualized image is transferred is heat-fixed by a fixing unit 13 arranged on the other end side of the apparatus main body 1 and discharged.

The fixing unit 13 is arranged such that the fixing roller 14 provided with a heater is on the upper side and the pressure roller 15 is on the lower side, and the transfer surface side of the recording paper on which the visualized image is transferred is the fixing roller 14 side. By passing through the pressure contact portion, heat fixing is performed. The pressure roller 15 is urged upward by a spring 18 and comes into pressure contact with the fixing roller 14.

On the other end side of the apparatus main body 1, a lever 16 constituting a releasing means is arranged. This lever 16
2 is a V-shaped member that rotates up and down about a fulcrum 17 as shown in FIG. 2. One side 16a extending from the fulcrum 17 constitutes an operating part, and the middle bottom part thereof is a pressing roller 15.
It comes into contact with the upper side of the rotating shaft 15a, and its tip projects outside the apparatus body 1. The tip of the other side 16b extending from the fulcrum 17 is adapted to engage with the upper side of the rotary shaft 3a of the photosensitive drum 3.

That is, when the cover 2 is closed with respect to the apparatus main body 1, the lever 16 is urged upward by the spring 18 so that the one side 16a constituting the operating portion is pushed up. As a result, the other side 16b is deviated in the clockwise direction around the fulcrum 17, and the photoconductor drum 3 is fixed to the apparatus main body 1 side at its tip.

In the embodiment having such a structure, the photosensitive drum 3 rotates clockwise in the figure, is uniformly charged by the charging device 4, and is then exposed by the laser beam 7a from the laser scanner unit 7 to be statically charged. A latent image is formed. This electrostatic latent image is developed and visualized by the developer from the developing device 5. Then, the visualized image is transferred by the transfer device 6 to the recording paper fed from the paper tray 11. The recording paper on which the visualized image is transferred is heat-fixed by the fixing unit 13 and discharged.

When a recording sheet jams near the entrance to the fixing unit 13 in such a series of image forming processing steps, one side 16a of the lever 16 which is an operating portion is indicated by a dotted line in FIG. The tip end of the is rotated downward.

As a result, the pressure roller 15 is pushed down and the pressure contact state with the fixing roller 14 is released. At the same time, the tip of the other side 16b of the lever 16 is disengaged from the rotary shaft 3a of the photosensitive drum 3, and the fixing state of the process unit to the apparatus main body 1 is released.

In this state, the cover 2 is opened from the apparatus main body 1 as shown in FIG. 4, and the process unit is pulled out obliquely upward in the drawing, so that a hand can be easily inserted near the entrance to the fixing unit 13. Therefore, the jammed recording paper can be easily taken out.

Even if the recording paper is jammed in the fixing unit 13, the pressure roller 1 is operated by operating the lever 16.
Since 5 is pushed down, the recording paper can be easily taken out also in this case.

As described above, since the pressing state of the fixing roller 14 and the pressure roller 15 and the fixing state of the process unit to the apparatus main body 1 can be released at the same time by operating one lever 16, the jammed recording paper can be removed. It will be easy. Further, the structure is simplified, and the size of the entire apparatus can be sufficiently reduced.

Next, another embodiment of the present invention will be described with reference to the drawings. In this embodiment, only the main parts are shown, the same parts as those in the above embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

In the structure shown in FIG. 5, a rod-shaped lever 21 which rotates about one end as a fulcrum is used as an operating portion, one end of a wire 22 is fixed to the other end of the lever 21, and the wire 22 is fixed to the pressure roller 15. The rotary shaft 15a is in contact with the rotary shaft 15a and is located below the rotary shaft 15a and below the fulcrum 23 and above the fulcrum 23 at a height substantially equal to the rotary shaft 3a of the photosensitive drum 3. The other end of the wire 22 is fixed to a jig 25 for fixing the photosensitive drum 3 to the apparatus main body via the upper side of each of the fulcrums 24 to form a releasing means.

In this embodiment, when a paper jam occurs, the lever 21 is rotated counterclockwise in the figure to the position shown by the dotted line in the figure. As a result, the wire 22 is pulled, whereby the pressure roller 15 is pulled down, and at the same time, the jig 25 is disengaged from the photosensitive drum 3 and the engaged state is released.

Therefore, also in this embodiment, the pressing state of the fixing roller 14 and the pressure roller 15 and the fixing state of the process unit to the apparatus main body 1 can be released at the same time by operating the lever 21. The effect can be obtained.

The one shown in FIG. 6 uses a lever 31 having a kind of cam structure as a releasing means. Normally, the lever 31 is in the position shown by the solid line in the figure, and the tip portion 32 of the lever 31 is exposed. The process unit is fixed to the apparatus main body 1 by engaging with the rotary shaft 3a of the body drum 3.

When a paper jam occurs, the other end of the lever 31, which is the operating portion, is pulled horizontally as indicated by the dotted line in the figure. As a result, the cam portion 33 formed on the bottom of the lever 31
Contacts the rotating shaft 15a of the pressure roller 15 and presses the pressure roller 15 downward. As a result, the pressure contact state between the fixing roller 14 and the pressure roller 15 is released. At the same time tip 3
2 is disengaged from the photoconductor drum 3 and the engaged state is released.

Therefore, also in this embodiment, the pressing state of the fixing roller 14 and the pressure roller 15 and the fixing state of the process unit to the apparatus main body 1 can be released at the same time by operating the lever 31, so that it is the same as in the previous embodiment. The effect can be obtained.

[0035]

As described above, according to the present invention, the releasing means for releasing the pressure contact state between the fixing roller and the pressure roller is also configured to fix and release the process unit with respect to the apparatus main body. When the clogs are clogged, the removal work becomes easy and the size can be sufficiently reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a main configuration of the embodiment.

FIG. 3 is a diagram for explaining the operation of the main part of the embodiment.

FIG. 4 is a sectional view showing a state in which a cover is opened in the embodiment.

FIG. 5 is a main part configuration diagram showing another embodiment of the present invention.

FIG. 6 is a configuration diagram of a main part showing still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Device body 3 ... Photosensitive drum 4 ... Charging device 5 ... Developing device 6 ... Transfer device 13 ... Fixing unit 14 ... Fixing roller 15 ... Pressure roller 16 ... Lever

Claims (1)

[Claims] 1. An image forming apparatus comprising a process unit integrally having a part or all of image forming means for transferring and forming an image on a recording medium, and the process unit being detachable from an apparatus main body. , A fixing roller and a pressure roller are arranged in pressure contact with each other, and a fixing unit for fixing the image on the recording medium by passing the recording medium on which the image is formed through the pressure contact portion of each roller, and the fixing roller and the pressure of this fixing unit. An operation unit for releasing the pressure contact state of the rollers is provided, the process unit is fixed to the apparatus main body at all times, and release means for releasing the fixation of the process unit to the apparatus main body by the release operation of each roller by the operation unit. An image forming apparatus characterized by being provided.