JPH05257337A - Image forming device - Google Patents

Abstract

PURPOSE:To solve various problems in positioning precision, facilitating jamming processing, etc., and to make the device even more 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 and the transfer means assembled integrally to a unit body 3 which can be unloaded from the device body, and the unit body 3 is provided unloadably along the direction separating from the periphery surface of the drum, or the unit 3 can be placed within the device positioned in a space which is at least above the center of the photosensitive drum 4, or at least one of the two means is assembled to be freely rockably against the unit body 3, and furthermore a U shaped carrying path surrounding the photosensitive drum is utilized.

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, a transfer roller is generally used because the toner used in this apparatus is often a conductive toner. However, when the transfer means is constructed using such a roller, it contacts the recording paper. Therefore, it is necessary to clean it regularly because it is contaminated with paper powder, and because the drum side that rotates by rolling is high hardness α-Si, it is necessary to replace it in the unit of tens of thousands due to its wear deterioration. There is.

Therefore, both of the above process means must be detachably attached 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 solve such a drawback, it is preferable to integrate the above two means into a unit, but various problems occur when the two devices are unitized. The first
Is the problem of position accuracy. That is, since the transfer roller is arranged in contact with the drum, while the sleeve constituting the developing means is arranged in proximity to the drum, it is difficult to maintain the positional accuracy of these members with high accuracy when unitized. However, if the unit is configured to be removable along the direction of the center line of the drum, the unit must be once separated from the drum to be removed in order to avoid rubbing between the drum and the both members. If such a detaching process is added, the positional precision of the developing sleeve is likely to be misaligned due to the repeated detaching operation, and as a result, the image quality is likely to be deteriorated.

The second problem is toner replacement. That is, as the apparatus is downsized, the toner storage capacity in the developing apparatus becomes smaller and the toner needs to be frequently replaced. However, it is a heavy burden on the user to integrally take out a plurality of process means each time the toner is replaced. Not only that, but due to the repeated disengagement operation, the unit mounting accuracy, in other words, the positional accuracy of the both members is lowered.

The third problem is the jam clearance problem. That is, even if a conveyance path for guiding the recording paper to the transfer position is formed inside the unit or on the apparatus main body side, the frame body constituting the unit conceals the side surface side of the conveyance path, making jam processing difficult.

The respective inventions described below provide a back exposure apparatus which can solve the above-mentioned drawbacks respectively even when the above-mentioned both parts are integrated to form a unit, thereby further downsizing. To aim for things. Another object of the present invention is to provide a back exposure apparatus capable of maintaining a high degree of positional accuracy of the developing sleeve and the like even when the both parts are integrated to form a unit, and even when the unit is repeatedly attached and detached. The purpose is to provide. Another object of the present invention is to provide a backside exposure apparatus that can easily achieve the replacement of the toner and the unitization of the both parts. Another object of the present invention is to provide a back exposure apparatus which can easily achieve jam processing even when the above two parts are integrated to form a unit.

[0011]

Next, the structure and operation of the invention described in each of claims 1 to 5 will be described. However, these inventions are not contradictory to each other and can be selectively selected according to a desired purpose. It is possible to use a plurality of inventions in combination. Each of the inventions described in claims 1 to 5,
It is characterized in that the developing means and the transfer means are integrally assembled to a unit body which is removable from the main body of the apparatus. As a result, there is only one guide means for removing each means.
This is preferable because the apparatus configuration can be prevented from becoming complicated and the size can be prevented from increasing, and the durability of both means is in the unit of tens of thousands of sheets.

According to the first aspect of the present invention, the unit body can be pulled out in a direction away from the drum peripheral surface without being pulled out in the axial direction. As a result, it is possible to remove the unit in one step without adding a detaching step of detaching the unit from the drum once in order to avoid rubbing between the drum and the both members. A guide groove may be formed along the guide groove, and the guide groove may be stopped at the end position. In other words, since two points can be easily supported in the axial direction, the position accuracy can be maintained with high accuracy. Further, by adopting the above-mentioned configuration, when the transport path for guiding the recording paper to the transfer position is formed on the apparatus main body side, the transport path in the vicinity of the transfer position can be easily opened, and the transport path can be provided in the unit. Even when forming, since the detaching direction of the unit is the direction of contacting and separating from the conveying direction of the recording paper, even if the paper is jammed in the vicinity of the transfer position, the paper will not be damaged and can be easily united with the unit. You can pull out the paper.

On the other hand, the invention according to claim 2 is characterized in that the unit body can be arranged in an apparatus located at least in a space above the center of the photosensitive drum. According to this structure, the unit body can be arranged so as to face the upper surface side of the housing, whereby the toner supply port of the developing device is provided on the upper surface of the unit body to easily replace the toner. I can do things.

As described above, it is difficult to maintain the high positional accuracy of the two members, that is, the developing means and the transfer means, with respect to the photosensitive drum with one unit body. Therefore, in the invention described in claim 3, the developing means and the transfer means are integrally assembled to the unit body, and at least one of the both means, more specifically, the transfer roller is shaken with respect to the unit body. It is characterized by being freely assembled. Therefore, it suffices to maintain the positional accuracy between the developing sleeve and the drum with high accuracy regardless of the positional accuracy of the transfer roller, and the position regulating means of the unit becomes easy. In this case, by equalizing the pressure contact force of the transfer roller by assembling the transfer roller in the unit body so as to be swingable in the contacting and separating direction from the peripheral surface of the drum.

Further, as described above, mounting the unit body in the apparatus main body so that it can be detached from the drum in the direction of contact and separation requires a dead space for detachment, and the transfer means must be located on the recording paper conveyance path. Since it has to be provided, the removal direction is greatly restricted, and it is difficult to set it in the preferable position as described above. In view of this, the present invention is characterized in that it is curved so as to be substantially in contact with the photosensitive drum corresponding to the transfer position of the recording paper conveyance path formed on the apparatus main body side, and a part of the curved portion is formed in the unit. To do. According to this feature, the conveying path is formed in a substantially U shape so as to face the peripheral surface of the photosensitive drum as shown in the embodiment described later, and the unit is attached to the tip of the U-shaped portion. The direction of pulling out the unit can be set at an arbitrary angle of 180 °, and the drum forming space and the transport path forming space can be divided into left and right, which is preferable in terms of layout and downsizing of the device. ..

[0016]

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 structure of the printer according to the embodiment of the present invention, in which a sheet feeding port 11 is opened on the upper side of the front wall of the thick rectangular frame 1 whose longitudinal direction is set back and forth, and a sheet discharging port 12 is opened on the lower side. Then, the paper feed cassette 13 and the paper discharge tray 14 are mounted in the respective openings 11 and 12. A substantially horizontal U-shaped recording paper transport path 2 is formed so as to connect the paper feed port 11 and the paper discharge port 12. In this case, in order to secure a space for disposing the unit body 3 and the photosensitive drum 4 which will be described later, the U-shaped top portion of the transport path 2 is limited to a substantially central position of the apparatus body. A transfer roller 31 is provided near the U-shaped top portion, a paper feed roller 21 and a registration roller 32 are provided on the upstream transport path, and a fixing roller 22 is provided at the downstream corner of the apparatus main body. ..

On the other hand, on the lower side of the space on the right side of the figure of the apparatus main body, a photosensitive drum 4 in which an exposure head 40 is included so as to face the transfer roller 31, and a driving force is applied to the photosensitive drum 4 via a belt 51. Drive motors 5 for providing the above are respectively provided. In addition, in the space above the photosensitive drum 4, the developing device 6 together with the transfer roller 31 and the registration roller 32 are provided.
A unit body 3 is integrally assembled.
A lid 19 is attached to the upper surface of the device above the unit body 3 so as to be opened. By opening the lid body 19, the unit body 3 can be taken out upward using the guide grooves 17 and 18. It is configured.

Next, the configuration of each part will be described. As is well known, the photosensitive drum 4 is formed by laminating a transparent conductive layer and a photoconductive layer on a transparent support sleeve, and
The drum 4 is configured to be rotatable in the direction of the arrow, and the drum 4 is transmitted by transmitting the driving force of the driving motor 5 via the belt 51.
The transfer roller 31 and the transfer roller 31 can be rotated synchronously. The exposure head 40 generates an optical output corresponding to image information L
It is composed of an ED column 40a and a converging lens 40b (trade 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 4 and the developing sleeve 61.

The unit body 3 is installed on the unit wall surfaces 3a at both ends in the axial direction by the two support shafts 33a and 33b so as to be positionally regulated at the ends of the guide grooves 17 and 18, and the developing device for the unit body 3 is also provided. A paper feed path 34 is formed along the transport path 5 in the air space sandwiched by the transfer roller 31 and the transfer roller 31, and the registration roller 32 is disposed on the paper feed path 34.

The developing device 6 effectively utilizes the partition wall 34a forming a part of the paper feed path 34 and the unit outer wall 3b to form the toner accommodating portion 60, and the lower surface opening of the toner accommodating portion 60 is brought close to the photosensitive drum 4. A developing sleeve 61 is provided, and a toner replenishing port is further formed on the upper surface side of the toner accommodating portion 60 so that the toner can be replenished by opening the lid 19.

On the other hand, the transfer roller 31 has its base end side rotatably attached to the free end side of an arm 38 pivotally supported by the unit wall surface 3a, and a photosensitive drum 4 is urged by a spring 37 urged by the arm 38. It is configured so that it can be pressed against the peripheral surface with a predetermined pressure.

Next, the operation of this embodiment will be described. First, while receiving the rotational force of the drive motor 5 to rotate the photosensitive drum 4 in the direction of the arrow, the optical output of the exposure head 40 arranged on the inner peripheral side of the photosensitive drum 4 is focused to form a latent image on the photoconductor layer. Simultaneously with or immediately after the image is formed, the latent image is made into a visible image (toner image) through the developing sleeve 61 arranged in proximity to the photosensitive drum 4.

On the other hand, on the transport path 2 side, the recording paper fed by the paper feed roller 21 to the entrance end of the registration roller 32 in the paper feed path 34 is inserted into the transfer position in synchronization with the toner image. The toner image can be transferred onto the recording paper via the transfer roller 31, and after the image is fixed by the fixing roller 22, the paper can be discharged onto the paper discharge tray 14 through the paper discharge opening 12.

When a predetermined number of image forming operations are repeated and the toner becomes empty, the lid 19 on the upper surface of the apparatus main body is opened and the toner is supplied from the toner supply port.
Further, when the transfer roller 31 or the developing device 6 is deteriorated or jammed, the lid 19 is opened, and then the unit body 3 is taken out upward along the guide grooves 17 and 18, so that the vicinity of the transfer position is obtained. Since the conveyance path is opened, jam processing is easily performed, and the transfer roller 31 and the like on the side of the unit body 3 taken out can be replaced.

After the jam is removed or the transfer roller 31 is replaced, the unit body 3 is dropped along the guide grooves 17 and 18 to automatically regulate the position of the unit body 3 at the end positions of the guide grooves 17 and 18. The distance between the developing sleeve 61 and the drum 4 is maintained and set accurately. At this time, since the transfer roller 31 is elastically urged in the direction of approaching the drum 4 by the arm 38, it is possible to absorb a slight variation in the diameter of the transfer roller 31 and always press it with a predetermined pressure.

FIG. 2 shows another embodiment in which the transfer roller 31 is fixed to the unit body 3 without oscillating, and in the case of this embodiment, it is fixed at the end position of the guide groove 17 '. In addition, the positional accuracy can be maintained accurately with the sleeve 61 being supported at two points between the support shaft 21 and the transfer roller 31 that is in contact with the drum 4, and the sleeve 61 being close to the drum 4. In this embodiment, the sheet feeding tray 13 'is used for sheet feeding without using the sheet feeding cassette. Therefore, also in such an embodiment, the operation of the present invention described above can be achieved smoothly.

[0027]

As described above, according to the present invention, even when both the developing means and the transferring means are integrated to form a unit, and the developing sleeve is repeatedly attached and detached, It is possible to maintain a high degree of positional accuracy. Further, according to the present invention, it is possible to easily achieve unitization of both the components while achieving the ease of toner replacement. Further, according to the present invention, even when the both parts are integrated to form a unit, facilitation of jam processing can be easily achieved. 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 schematic diagram showing an internal configuration of an image forming apparatus according to another embodiment of the present invention.

[Explanation of symbols]

 31 transfer roller 6 developing means 3 unit body 22 paper feed path 4 photoconductor drum 40 exposure means

Claims (5)

[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. An image forming apparatus characterized in that the developing means and the transfer means are integrally assembled and that the unit body can be pulled out along a direction in which the unit body is separated from the drum peripheral surface. 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 in which an exposing unit is arranged, and the unit unit is removable from the apparatus main body. An image forming apparatus characterized in that the developing means and the transfer means are integrally assembled and the unit body is arranged in an apparatus located at least in a space above the center of the photosensitive drum. 3. An image forming apparatus in which a developing means and a transfer means are sequentially arranged along a drum rotation direction around a photosensitive drum having an exposing means arranged therein, and a unit body which is removable from an apparatus main body. An image forming apparatus characterized in that the developing means and the transfer means are integrally assembled, and at least one of the both means is swingably assembled to a unit body. 4. The image forming apparatus according to claim 3, wherein the means is a transfer means, and is assembled so as to be swingable in a contacting / separating direction from a peripheral surface of the drum. 5. An image forming apparatus in which a developing means and a transferring means are sequentially arranged along a drum rotation direction around a photosensitive drum having an exposing means inside, and a unit body which is detachable from a main body of the apparatus. The developing unit and the transfer unit are integrally assembled, and the developing unit and the transfer unit are curved so as to be substantially in contact with the photosensitive drum corresponding to the transfer position of the recording sheet conveying path formed on the apparatus main body side, and a part of the curved portion is formed in the unit. Image forming apparatus characterized by being formed inside