JPH05257339A - Image fomring device - Google Patents

Abstract

PURPOSE:To solve various problems in positioning precision, facilitating jamming processing, etc., and to make the device furthermore compact even when a developing means and a transfer means placed in the periphery of a photosensitive drum are integrated into a unit in a so called backside exposure device. CONSTITUTION:The device has the developing means 15 and the transfer means 8 assembled integrally to a unit body 20 which can be unloaded from the device main body, a paper feeding path 22 feeding recording paper to a transfer position is provided within the unit 20, the developing means 15 and the transfer means 8 are placed with the paper feeding path 22 in between or the developing means and the transfer means are placed so that a supporting point, the transfer position and the developing position are placed within the range of 180 degrees from the center of the drum.

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 having an exposing means provided in a photosensitive drum carrying a toner image, and more particularly to an image forming apparatus which facilitates maintenance.

[0002]

2. Description of the Related Art Conventionally, on the inner peripheral side of a photosensitive drum formed by laminating a transparent conductive layer and a photoconductive layer on a transparent support,
Arrangement of exposure means for generating light output corresponding to image information,
At the same time as or immediately after the light output of the exposing means is focused to form a latent image on the photoconductor layer, the latent image is visualized (toner) through a developing means facing the photosensitive drum. An image forming apparatus is known in which the toner image can be transferred to plain paper through a transfer roller or other transfer means after being converted into an image. (JP-A-58-153957, etc., hereinafter referred to as back exposure device)

In this type of apparatus, unlike the Carlson type electrophotographic apparatus in which the exposing means is arranged on the outer peripheral surface of the photosensitive drum, the exposing means is arranged in the drum, and the position between the exposing means and the drum is also set. Since the precision must be maintained at a high level, the exposure means and the drum are integrated with each other, and amorphous silicon α-Si is used for the drum to enable semi-permanent use.

[0004]

However, in the developing means provided around the drum, it is necessary to regularly replace the toner and the carrier, and when the toner accommodating portion is made into a cartridge which is detachable from the developing means main body. Also in this case, the sleeve, the fixed magnet assembly, etc. constituting the developing means reach the use limit in the unit of tens of thousands of sheets, and it is necessary to replace them. Also in the transfer means, since the toner used in this apparatus is often conductive toner, a transfer roller is generally used. However, if the transfer means is configured by using such a roller, the paper powder will come into contact with the recording paper. Therefore, it is necessary to regularly clean the drum, and since the drum side that rotates by rolling is made of high hardness α-Si, it is necessary to replace it in units of tens of thousands due to its wear deterioration.

Therefore, both of the above process means need to be detachably provided to the device body without being fixedly attached to the device body. Each of the guide means must be provided independently, which complicates and increases the size of the device. In order to eliminate such a drawback, it is preferable to integrate both of the above means into a unit, but various problems occur in uniting the two devices.

One of them is the problem of recording paper conveyance. That is, in the above apparatus, a transport path for guiding the recording paper must be provided in the transfer position due to its structure, but it is extremely difficult to form the transport path when the both means are integrated.

The second is the problem of positional accuracy. That is, since the transfer roller is arranged in contact with the drum, while the sleeve constituting the developing means is arranged close to the drum,
These must be separated from the drum once to be separated, and if such a separation step is added, the positional accuracy of the developing sleeve, which must maintain the distance between the drum and the drum with high accuracy, is not correct. This is likely to occur, and as a result, image quality is likely to deteriorate.

In view of the above-mentioned drawbacks of the prior art, the present invention provides a rear exposure apparatus which can easily guide the recording paper to the transfer position even when the above-mentioned two parts are integrated into a unit. With the goal. Another object of the present invention is to
An object of the present invention is to provide a backside exposure apparatus capable of maintaining a high degree of positional accuracy of the developing sleeve and the like even when the above two parts are integrated into a unit and the unit is repeatedly attached and detached.

[0009]

The invention according to claim 1 is
The first feature is that the developing unit and the transfer unit are integrally assembled to a unit body that is removable from the apparatus main body. As a result, only one guide means is required for removing each means, the apparatus structure is not complicated, and it is possible to avoid an increase in size. In particular, the durability of both means is on the order of tens of thousands of sheets. It is preferable because it is done.

A second feature is that a paper feed path for feeding recording paper is provided at the transfer position in the unit body, and the developing means and the transfer means are located with the paper feed path sandwiched therebetween. It is characterized by having been arranged. As a result, since the paper feed path is also provided inside the unit, the recording paper can be guided to the transfer position accurately and surely. In this case, since the registration roller has durability, it may be provided in the unit or may be left on the apparatus main body side.

The invention according to claim 2 is the same as the first invention in that it has a unit body for integrally assembling the developing means and the transfer means, but the present invention is particularly applicable to the unit body. The first feature is that the unit body is swingable in the contact and separation directions from the drum peripheral surface around the fulcrum. As a result, the transfer roller constituting the transfer means comes into contact with the drum peripheral surface supported on the apparatus main body side, and as a result, the unit is held at the apparatus main body side by the two-point support. As a result, high positional accuracy can be maintained even if the unit attaching / detaching operation is repeated, even if the sleeve body constituting the developing means is disposed close to the drum peripheral surface in a non-contact state between the fulcrum and the transfer roller. It is possible.

A second feature of the second invention is that the transfer position and the developing position are located at least on one side of a straight line passing through the fulcrum and the center of the drum, in other words, within a range of 180 degrees about the drum. That is, the developing means and the transfer means are provided. As a result, even if the transfer roller (developing sleeve) at the fastest position can be swung around the fulcrum, the transfer roller (developing sleeve) can be reliably separated without rubbing against the drum surface, and the process means are not damaged. The subsequent extraction process is easy.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described in detail below as an example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Not too much. Figure 1
Shows an internal configuration of a printer according to an embodiment of the present invention, in which a sheet feeding cassette 2 is provided on the front side of a thick rectangular frame 1 whose longitudinal direction is set back and forth, and a sheet ejection opening 3 at the rear end is provided on the upper side. The paper discharge portions 4 are formed to face the front side and obliquely upward, respectively.

Then, a paper feed roller 6, a registration roller 7, a transfer roller 8, a fixing roller 9, and a paper discharge are provided from a front end of the paper feed cassette 2 toward a paper discharge opening 3 along a laterally J-shaped conveying path 5. A roller 10 is provided, while the transfer roller 8 is provided.
A photoconductor drum 12 including an exposure head 11 is disposed on the upper surface side of the in contact with the transfer roller 8, and both are configured to be synchronously rotatable by a drive system (not shown). Further, a developing device 15 is arranged above the transfer roller 8, and a developing sleeve 15a in the device is arranged to face the photoconductor drum 12 so as to face it.

Further, the developing device 15, the registration roller 7,
The transfer roller 8 and the transfer roller 8 are integrally assembled by the unit body 20. Next, the configuration of each part will be described.

As is well known, the photosensitive drum 12 is formed by laminating a translucent conductive layer and a photoconductive layer on a translucent support sleeve and is rotatable in the arrow direction.

The exposure head 11 includes an LED array 11a for generating a light output corresponding to image information and a focusing lens 11b.
(Product name: SELFOC lens), and is configured to form an image on the photoconductor layer located on the focal line connecting the axis of the photosensitive drum 12 and the developing sleeve 15a.

The unit body 20 is pivotally supported in the axial direction of the drum 12 by a support shaft 21 located above the drum 12, and the developing sleeve 1 of the unit body 20 is supported.
A paper feed path 22 is formed along the transport path 5 in an empty area sandwiched between 5a and the transfer roller 8, and the registration roller 7 is disposed on the paper feed path 22. Then, the arrangement positions of the respective members are considered so that the contact position between the support shaft 21 and the transfer roller 8 is located within a range of 180 ° C. around the drum 12 axis.

As a result, even when the support shaft 21 is swung in the direction away from the peripheral surface of the drum 12, the transfer roller 8 can be smoothly separated without rubbing the surface of the drum 12.

On the rear side of the unit body 20 located on the opposite side of the drum 12, the unit body 20 is provided with a spring 23a.
An urging member 23 for pressing the drum 1 toward the drum 12 is attached, which allows the transfer roller 8 to have an appropriate pressing force.
It can be pressed against two surfaces. As shown in FIG. 2, the urging member 23 can release the pressing force by rotating the pressing force release lever 24 located on the side wall surface 26 of the frame body 1. Reference numeral 27 denotes an opening / closing lid provided outside the side wall surface 26.

Reference numeral 25 is a release spring for rotating the unit body 20 in a direction of separating from the drum 12 when the release lever 24 is rotated.

Next, the operation of this embodiment will be described. First, while rotating the photoconductor drum 12 in the direction of the arrow, the light output of the exposure head 11 arranged on the inner peripheral side of the photoconductor drum 12 is focused to form a latent image on the photoconductor layer. The latent image is made into a visible image (toner image) through the developing sleeve 15a which is disposed in close proximity to the lens 12.

On the other hand, on the side of the conveying path 5, the recording paper fed to the entrance end of the registration roller 7 by the paper feed roller 6 is inserted into the transfer position in synchronization with the toner image.
The toner image can be transferred onto plain paper via the transfer roller 8, and after the image is fixed by the fixing roller 9, the paper can be ejected onto the paper ejection unit 4 via the paper ejection roller 10 and the paper ejection opening 3.

When the image forming operation is repeated for a predetermined number of times and the transfer roller 8 or the developing device 15 is deteriorated or the toner needs to be replaced, the urging force of the urging member 23 is released by rotating the release lever 24. By doing so, the transfer roller 8 is automatically separated from the peripheral surface of the drum 12 by the urging force of the release spring 23a, and in this state, the unit body 20 can be discharged to the outside by using the support shaft 21 as a guide.

When the unit body 20 is reattached, the urging member 23 resists the urging force of the release spring 25 by performing the operation opposite to the above operation.
It is rotated to the 2 side, and the transfer roller 8 is pressed against it. As a result, the unit body 20 is supported at two points between the support shaft 21 and the transfer roller 8, and the positional accuracy of the unit body 20 can be maintained accurately with the sleeve 15a being close to the drum 12. According to this embodiment, the operation of the present invention described above can be smoothly achieved.

[0026]

As described above, according to the present invention, the recording paper can be easily guided to the transfer position even when the developing means and the transfer means are integrated into a unit.
Further, according to the present invention, the positional accuracy of the developing sleeve or the like can be maintained at a high level even when the both means are integrated to form a unit, and even when the unit body is repeatedly attached and detached. And so on.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating an internal configuration of an image forming apparatus according to an exemplary embodiment of the present invention.

FIG. 2 is a perspective view showing an outer portion of the device shown in FIG.

[Explanation of symbols]

 8 Transfer Roller 15 Developing Means 20 Unit Body 22 Paper Feeding Path 12 Photosensitive Drum 11 Exposure Means

Claims (3)

[Claims] 1. An image forming apparatus in which a developing unit and a transfer unit are sequentially arranged along a drum rotation direction around a photosensitive drum in which an exposing unit is arranged, and the unit unit is removable from the apparatus main body. The developing means and the transfer means are integrally assembled, a paper feed path for feeding recording paper is provided at the transfer position in the unit body, and the developing means and the transfer means are positioned with the paper feed path sandwiched therebetween. Image forming apparatus characterized by being provided 2. An image forming apparatus in which a developing unit and a transfer unit are sequentially arranged along a drum rotation direction around a photosensitive drum having an exposing unit inside, from a drum peripheral surface around an arbitrary fulcrum. The developing means and the transfer means are integrally assembled to a unit body which can be swung in the contact / separation direction, and the developing means is arranged such that the fulcrum, the transfer position and the developing position are located within a range of 180 ° from the drum center. And an image forming apparatus having a transfer unit. 3. The transfer means is composed of a roller body capable of contacting with the drum peripheral surface, and a sleeve body constituting the developing means is located between the fulcrum and the roller body so as to be in non-contact with the drum peripheral surface. The image forming apparatus according to claim 2, wherein the image forming apparatuses are arranged.