JPH07253697A - Color image forming device - Google Patents

Abstract

PURPOSE:To make a cartridge of integrally incorporating a photoreceptor drum etc. well-balanced, compact, attachable and detachable to and from the device main body with a simple operation, and capable of setting a position in including an exposure optical system of the main body side with high accuracy. CONSTITUTION:The color image forming device is constituted so that the cartridge is made compact with an excellent operability by respectively arranging such as the plural electrifying unit 11 and developing unit 13 located on the peripheral surface of the photoreceptor drum 10 in the symmetrical and well- balanced position, a supporting member 20 for attaching the exposure optical system 12 fixed on the main body side is made in a state included by the photoreceptor drum 10 at the time of attaching to the main body and the photoreceptor drum 10 is disengaged form the device main body after the detach from the supporting member 20 at the time of taking out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention mainly arranges a plurality of image exposing means and developing means on the peripheral surface of a drum-shaped image forming body to form toner images by superposing them during one rotation of the image forming body. The present invention relates to an electrophotographic color image forming apparatus.

[0002]

2. Description of the Related Art As a method for forming a multicolor image, a monochromatic toner image formed on each photoconductor is intermediately transferred by equipping the photoconductor with the same number of images as necessary, a charger and a developing device. A device that creates a color image by superimposing it on an image (A)
An apparatus (B) for forming a color image by repeating charging, image exposure and development for each color by rotating one photoreceptor a plurality of times, or similarly, charging and image exposure for each color within one rotation of one photoreceptor. An apparatus (C) and the like for forming a color image by sequentially performing development are known.

However, the above-mentioned device (A) has a drawback that the volume of the device is increased because a plurality of photoconductors and intermediate transfer members are required, while the device (B) has a charging means, an image exposing means and a photoconductor. However, there is a restriction that the size of the formed image is limited to the surface area of the photoreceptor or less, though the volume is reduced.

Although the apparatus (C) is capable of high-speed image formation, it is necessary to dispose a plurality of sets of a charger, an image exposure means and a developing device within one circumference of the photosensitive member, and an optical system for image exposure. There is a possibility that the toner leaking from the developing device close to the system may stain the image quality and impair the image quality.To avoid this, the distance between the image exposing means and the developing device needs to be increased, so the diameter of the photoconductor inevitably increases. There is a contradiction that the device will become larger.

For the purpose of avoiding the drawbacks of the above-mentioned obstacles in the apparatus (C), the substrate of the image forming body is made of a transparent material, and a plurality of image exposing means are housed therein to form an image. An apparatus has been proposed in which the photosensitive layer formed on the outer periphery of the substrate is exposed through the substrate (for example, JP-A-5-307307).

[0006]

However, the apparatus according to the above-mentioned proposal has a complicated structure because a large number of image exposing means are provided inside the image forming body and a large number of chargers and developing devices are provided outside the image forming body.
It is difficult to attach and detach the developing device, the image forming body, and the image exposing means, which deteriorates the handleability, and it is difficult to maintain the positional accuracy between the respective devices. In particular, by arranging the fixed optical system inside and rotating it on the image forming body,
Attaching and detaching is a difficult point. Further, it is preferable that the developing device and the like have a common structure as much as possible.

An object of the present invention is to provide a color image forming apparatus which is improved in this point and rationalizes a layout to maintain high balance and positional accuracy of equipment, is compact, and has good handling and operability.

[0008]

SUMMARY OF THE INVENTION The above-mentioned object is a color in which a toner image is formed on an image forming body by repeating charging, image exposure and development on the image forming body, and then collectively transferring to a transfer material. In the image forming apparatus, the image forming body is a drum-shaped image forming body, and includes the plurality of image exposing means fixed to the apparatus main body, and the image is formed with respect to a vertical line passing through the center of the drum-shaped image forming body. Two exposing means and two developing means are arranged at right and left positions, and further, a transfer means is arranged on one side of the vertical below the horizontal line passing through the center of the drum-shaped image forming body, and a cleaning means is arranged on the other side. A color image forming apparatus (first invention), and charging, image exposure and development are repeatedly performed on the image forming body to form toner images on the image forming body in a superimposed manner, and then collectively transferred to a transfer material. line In the color image forming apparatus, the image forming body includes the plurality of image exposing means fixed to the apparatus main body, and the image exposing position is a position upstream of the developing area of the developing means and inside the container of the developing means. A color image forming apparatus (second invention), and a drum-shaped image forming body is repeatedly charged, image-exposed and developed to form a toner image on the image forming body in a superimposed manner, In a color image forming apparatus that performs batch transfer to a transfer material, the image forming body includes a plurality of image exposing means fixed to the apparatus main body, and the image exposing is performed on a vertical line passing through the center of the drum-shaped image forming body. Two developing means and two developing means are arranged at left and right positions, respectively, and further, transfer means is provided on one side of the vertical line above the horizontal line passing through the center of the image forming body, and cleaning is provided on the other side. It is accomplished by a color image forming apparatus (the third aspect), characterized in that a stage.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of each embodiment of the present invention, the structure of a color image forming apparatus common to each invention will be described with reference to FIGS.

Reference numeral 10 denotes a drum-shaped image forming body, that is, a photosensitive drum, which is coated with a transparent conductive layer and an organic photosensitive layer (OPC) on the outer periphery of a cylindrical substrate formed of a transparent member such as optical glass or transparent acrylic resin. It was done.

A flange 10A at one end of the photosensitive drum 10 is provided with a guide pin 30 of a cartridge 30 described later.
The flange 10B at the other end is supported by P, and the flange 10B at the other end is fitted onto a plurality of guide rollers 40R provided on the substrate 40 of the apparatus main body to mesh the outer gear 10G with the drive gear 40G. Rotated clockwise with the layers grounded.

Reference numeral 11 denotes a scorotron charger, which is a photosensitive drum 10.
The above-mentioned organic photoconductor layer is charged by a grid held at a predetermined potential and corona discharge by a discharge wire to give a uniform potential to the photoconductor drum 10.

Reference numeral 12 denotes L arranged in the axial direction of the photosensitive drum 10.
In an exposure optical system composed of an ED and a self-occurring lens, image signals of respective colors read by a separate image reading device are sequentially taken out from a memory and inputted to the respective exposure optical systems 12 as electric signals. It

Each of the exposure optical systems 12 is mounted on a cylindrical supporting member 20 fixed to the substrate 40 of the apparatus main body with guide pins 40P1 as guides, and is mounted on the photosensitive drum 10.
Is housed inside the base body of.

Numerals 13Y to 13K denote developing units for accommodating yellow (Y), magenta (M), cyan (C), and K (black) developers, respectively, with predetermined gaps with respect to the peripheral surface of the photosensitive drum 10. Development sleeve 13 that keeps the same and rotates in the same direction
Equipped with 0.

Each of the developing devices is in a non-contact state by applying a developing bias voltage to the electrostatic latent image formed on the photosensitive drum 10 formed by the charging by the charging device 11 and the image exposure by the exposure optical system 12 described above. Reverse development with.

Next, the process of the color image forming apparatus in this apparatus will be described.

The original image is temporarily stored in an image reading device, which is separate from the present device, as an image read by an image pickup device or an image edited by a computer as an image signal for each color of Y, M, C and K. Are stored and stored in.

When the photoconductor drive motor is started by the start of image recording, the drive gear 40G is rotated to rotate the photoconductor drum 10 in the clockwise direction, and at the same time, the photoconductor is charged by the charger 11 (Y). Application of electric potential to the drum 10 is started.

After the photosensitive drum 10 is applied with an electric potential,
In the exposure optical system 12 (Y), the exposure by the electric signal corresponding to the first color signal, that is, the yellow (Y) image signal is started, and the yellow (Y) of the original image is formed on the photosensitive layer on the surface by the rotational scanning of the drum. ) Form an electrostatic latent image corresponding to the image.

The latent image is reverse-developed by the developing device 13 (Y) with the developer on the developing sleeve in a non-contact state, and a yellow (Y) toner image is formed according to the rotation of the photosensitive drum 10.

Next, the photosensitive drum 10 is further given a potential on the yellow (Y) toner image by the charging action of the charger 11 (M), and the second color signal of the exposure optical system 12 (M), that is, Exposure with an electric signal corresponding to the magenta (M) image signal is performed, and the non-contact reversal development by the developing device 13 (M) causes the magenta (M) toner image on the yellow (Y) toner image. Will be sequentially stacked.

By the same process, a cyan (C) toner image corresponding to the third color signal is further generated by the charging device 11 (C), the exposure optical system 12 (C) and the developing device 13 (C), and also the charging device. 11 (K), exposure optical system 12 (K) and developing unit 13
By (K), a black (K) toner image corresponding to the fourth color signal is sequentially superimposed and formed, and a color toner image is formed on the peripheral surface of the photosensitive drum 10 within one rotation.

Photoreceptor drum 10 by each of these exposure optical systems
The exposure of the organic photosensitive layer is conducted from the inside of the drum through the above-mentioned transparent substrate. Therefore, the exposure of the images corresponding to the second, third and fourth color signals is performed without any influence of the toner image previously formed.
It is possible to form an electrostatic latent image equivalent to the image corresponding to the color signal of. The stabilization of the temperature inside the photosensitive drum 10 and the prevention of the temperature rise due to the heat generation of each exposure optical system 12 use a material having good thermal conductivity for the supporting member 20, and use a heater 201 when the temperature is low, When the temperature is high, it can be suppressed to a level without any trouble by taking measures such as radiating heat to the outside through the heat pipe 202. Further, during the developing action by each developing device, a developing bias in which a direct current or an alternating current is applied to the developing sleeve 10 is applied, and jumping development is performed by the one-component or two-component developer accommodated in the developing device, and the transparent Non-contact reversal development is performed on the photoconductor drum 10 whose grounding is carried out on the conductive layer.

Thus, the color toner image formed on the peripheral surface of the photosensitive drum 10 is transferred to the transfer paper which is conveyed from the paper feed cassette 15 in the transfer device 14A and is fed in synchronization by the driving of the timing roller 16. It

The transfer paper on which the toner image has been transferred is a static eliminator.
In 14B, the charge is removed and the toner is separated from the peripheral surface of the drum. After the toner is fused in the fixing device 17, the toner is discharged via the paper discharge roller 18 onto the tray above the device.

On the other hand, the photosensitive drum 10 from which the transfer paper has been separated removes and cleans the residual toner in the cleaning device 19 to continue the formation of the toner image of the original image, or temporarily stops the toner image of the new original image. Formation.

The photosensitive drum 10, the charging devices 11, the developing devices 13, and the cleaning device 19 are the cartridge 3
It is constructed so that it can be attached to and detached from the main body of the apparatus while leaving the supporting member 20 having the exposure optical system 12 in the state of being housed in the unit 0 and integrated.

That is, the cartridge 30 is housed in a frame 50 shown in FIG.

The structure in which the supporting member 20 is left at the time of attachment / detachment is a heater.
201, heat pipe 202, lead wire 20 for operating the LED
It has a feature that the optical system 12 and the optical system 12 can be fixed to the supporting member 20 despite the rotation of the photoconductor and the attachment / detachment of the photoconductor. It can also be used to determine the axis of the photosensitive drum 10 as described below.

When mounted, the gantry 50 is composed of a side plate 50A and a pair of support pedestals 50B, on which the cartridge 30 is placed and slid horizontally along the guide rails 51 inside the main body in a locked state.

The mount 50 is a guide pin that supports the photosensitive drum 10 in the cartridge 30 when it is inserted into the apparatus.
30P is engaged with the support member 20 for mounting the exposure optical system 12 described above, and the flange 10B is provided before and after the support member 20 for mounting the substrate 40.
After being externally fitted to the side guide roller 40R, the side plate 50A is tightly fixed to the abutting portion 53 of the apparatus main body by using the tightening screw 52 as a fixing means. As a result, the axial center and the axial center position of the photosensitive drum 10 with respect to the image forming portion are determined.

When the pedestal 50 is pulled out from the inside of the apparatus at the time of dismounting, the photoconductor drum 10 causes the exposure optical system 12 described above.
The slide is stopped at a position separated from the support member 20 to which the guide is attached, and the guide rail 51 supports the slide rail.

The photosensitive drum 10 which is disengaged from the guide roller 40R provided on the substrate 40 by pulling out the mount 50.
The flange 10B is supported by several folding portions 30A formed integrally with the cartridge 30 and maintains the same axial center position as that at the time of insertion. Therefore, when the frame 50 is inserted again, the flange 10B is easily fitted on the guide roller 40R to set the photosensitive drum 10 at the normal axial position.

(Embodiment 1) An embodiment of the first invention in the present invention will be described with reference to FIG.

Since the photosensitive drum 10 has the exposure optical system 12 accommodated therein, the plurality of chargers 11 and the developing devices 13 described above may be provided on the outer peripheral surface of the photosensitive drum 10 even if the drum diameter is relatively small. It is possible, and the volume of the device can be made compact by using a small diameter drum having an outer diameter φ of 60 mm to 160 mm.

Further, as shown in FIG. 4, two vertical lines M--M passing through the center of the photosensitive drum 10 are used as symmetry axes, and two exposure optical systems 12 and two developing devices 13 are provided on the left and right sides of the vertical line M--M. By disposing the transfer device 14A on one side of the lower portion of the horizontal line N-N passing through the center and the cleaning device 19 on the other side, the cartridge 30 is kept in the left-right balance, and the handling operation becomes extremely easy.

As confirmed in the present embodiment, the exposure optical system 12 and the developing device 13 are positioned substantially opposite to each other on the left and right sides of the vertical line MM as shown in the drawing, and the center of the transfer device 14A is set to the horizontal line N-.
The angle θ1 on the upstream side of rotation of the photosensitive drum 10 from the vertical line MM below N is 5 to 40 degrees, while the cleaning device 19
The angle .theta.2 on the downstream side of the rotation of the photosensitive drum 10 from the vertical line MM below the horizontal line NN is 10 degrees to 50 degrees.
The angle .theta.3 and .theta.4 formed by the center of each developing sleeve of the pair of left and right developing devices 13 disposed at each position above and below the horizontal line N--N are within ± 20 degrees above and below, respectively. By setting the angles θ5 and θ6 formed with respect to the pair of left and right developing devices 13 arranged within the range of 45 degrees to 75 degrees, respectively, the peripheral portion of the photoconductor can be effectively used and external shape balance and vertical balance can be achieved. I was able to get a good layout. The transfer device 14A may be replaced with a transfer roller or a transfer belt instead of the corona discharger.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG.

Each of the exposure optical systems 12 faces the position of the most upstream rotation of the photosensitive drum 10 inside the container of each developing unit 13, that is, the drum surface near the inlet in the developing container as shown in FIG. Thus, the image exposure is performed immediately after the photosensitive drum 10 to which the electric potential is applied by the charging device 11 enters the container of each developing device 13.

Each developing device 13 has a function of drawing in and sucking the air layer on the drum peripheral surface into the container as shown by the broken line by the rotation of the photosensitive drum 10, so that the drum surface at the image exposure position and the charging device 11 are charged. Toner is prevented from scattering and adhering toward the surface, and a high potential is applied by the charger 11 and image exposure is performed by the exposure optical system 12 to form a high-quality electrostatic image. It is also possible to dispose the photoconductor drum 10 close to the developing device 13 and further reduce the diameter of the photoconductor drum 10. Further, by making the developing sleeve 130 rotate in the same direction as the photosensitive member, the above effect is further improved.

According to the embodiment, the appropriate exposure position of the exposure optical system 12 is r, the outer diameter of the photosensitive drum 10, and the photosensitive drum 10 from the entrance of the developing container to the center of the developing sleeve 130 which is the center of the developing area. Is .alpha.1 and the central angle between the exposure optical system 12 and the developing sleeve 130 is .alpha.2, it is substantially upstream from the developing area where the photoreceptor is developed, and from the inlet of the developing container to the developing sleeve 130. The effect is most remarkable at a position where the distance between the exposure optical system 12 and the developing sleeve 130 satisfies the condition of (2/3) × α1 × r <α2 × r <α1 × r with respect to the distance to the center of. It was also confirmed that there is no toner scattering due to image exposure, and that the time required for the potential of the photosensitive drum 10 to drop can be secured before reaching the development area after image exposure. The configuration of this embodiment can be similarly applied to the case where a belt photosensitive member is used.

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG.

In the apparatus of the present invention, a transfer means composed of a pressing roller 140 and a transfer belt 141 which is conveyed and rotated by the pressing roller 140 is provided at the upper part of the apparatus main body.
The toner image is transferred via the transfer roller 140 at the upper part of the photoconductor drum 10 to the transfer paper sucked and conveyed by.

Also in the case of this apparatus, since the photosensitive drum 10 has the exposure optical system 12 accommodated therein, even if the drum diameter is relatively small, the plurality of chargers 11 and the developing devices described above are provided on the outer peripheral surface thereof.
It is possible to arrange 13 etc., and the outer diameter φ is practically
It can be 60 mm, and does not require a drum having a diameter of 160 mm or more, thus realizing a compact device.

Further, a vertical line MM passing through the center of the photosensitive drum 10 is used as an axis of symmetry, and the exposure optical system 12 and the developing device are provided on the left and right sides thereof.
The cartridge 30 maintains a left-right balance by disposing two 13 each, a pressing roller 140 on one side above the horizontal line NN passing through the center of the photosensitive drum 10, and a cleaning device 19 on the other side. Easy to handle and easy to handle.

As confirmed by this embodiment, the angle θ1 on the upstream side of the rotation of the photosensitive drum 10 from the vertical line MM above the horizontal line NN with respect to the center of the pressing roller 140 is 5 ° to 40 °.
On the other hand, the contact portion of the cleaning device 19 on the other hand is also the horizontal line N.
-N above the vertical line MM, the angle .theta.2 on the downstream side of the rotation of the photosensitive drum 10 is 10 degrees to 50 degrees, and the center of each developing sleeve of the pair of left and right developing devices 13 arranged at the lower side. The angles .theta.3 and .theta.4 formed with the horizontal line N--N are up to 20 degrees each up and down, and the angles .theta.5 and .theta.6 formed with respect to the pair of left and right developing units 13 are 45 to 75 degrees, respectively. By setting the inside, it was possible to effectively utilize the periphery of the photoconductor and obtain a layout in which the external shape balance and the superposition balance were obtained.

[0048]

According to the present invention, also in the color image forming apparatus of the type in which the exposing means is contained in the image forming body, the image forming body is balanced with the charging means, the developing means and the like, as in a general apparatus. It is possible to integrate the layout into the cartridge and attach / detach it to / from the main body with high accuracy by simple operation. As a result, a color image forming apparatus that is compact and capable of high-speed printing with good maintenance workability is provided. It will be provided.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of a color image forming apparatus according to first and second aspects of the invention.

FIG. 2 is a sectional view of the main part of the device.

FIG. 3 is a perspective view showing a detachable type of the cartridge.

FIG. 4 is a layout diagram showing a layout in a cartridge.

FIG. 5 is an explanatory view showing an image exposure position.

FIG. 6 is a sectional view showing the arrangement of a color image forming apparatus according to the third aspect of the present invention.

[Explanation of symbols]

 10 Photoconductor drum 11 Charger 12 Exposure optical system 13 Developing device 14A Transfer device 14B Static eliminator 15 Paper feed cassette 17 Fixing device 19 Cleaning device 20 Supporting member 30 Cartridge 30P Guide pin 40 Substrate 40R Guide roller 50 Stand 51 Guide rail 140 Pressing Roller 141 Transfer belt

Claims (11)

[Claims] 1. A color image forming apparatus that repeats charging, image exposure and development on an image forming body to form a toner image on the image forming body in a superimposed manner and then collectively transfers the toner image onto a transfer material. The body is a drum-shaped image forming body and includes the plurality of image exposing means fixed to the apparatus main body, and the image exposing means and the developing means are left and right with respect to a vertical line passing through the center of the drum-shaped image forming body. A color image forming method is characterized in that two units are arranged at each position, and a transfer unit is arranged on one side of the vertical line below the horizontal line passing through the center of the drum-shaped image forming body and a cleaning unit is arranged on the other side. apparatus. 2. The image forming body has a diameter of 60 mm to 160 mm.
The color image forming apparatus according to claim 1, wherein the color image forming apparatus is a drum-shaped image forming body. 3. The color image forming apparatus according to claim 1, wherein the transfer unit is arranged on the upstream side of the vertical line position below the horizontal line by 5 to 40 degrees. 4. The color image forming apparatus according to claim 1, wherein the cleaning unit is installed 10 degrees to 50 degrees downstream from the vertical line position below the horizontal line. 5. The color image forming apparatus according to claim 1, wherein the image forming body is housed in a cartridge together with the plurality of charging units and the plurality of developing units and is detachably attached to the apparatus main body. apparatus. 6. A color image forming apparatus, wherein a toner image is superposedly formed on the image forming body by repeating charging, image exposure and development on the image forming body, and then a batch transfer is performed on a transfer material. The body includes the plurality of image exposure means fixed to the apparatus main body, and the image exposure is performed at a position upstream of the developing area of the developing means and inside the container of the developing means. apparatus. 7. A color image forming apparatus, wherein a drum-shaped image forming body is repeatedly charged, image-exposed and developed to form toner images on the image forming body in a superimposed manner, and then collectively transferred to a transfer material. The image forming body includes the plurality of image exposing means fixed to the apparatus main body, and two image exposing means and two developing means are provided at right and left positions with respect to a vertical line passing through the center of the drum-shaped image forming body. A color image forming apparatus comprising: a transfer unit disposed on one side of the vertical line above the horizontal line passing through the center of the image forming body; and a cleaning unit disposed on the other side of the vertical line. 8. The color image forming apparatus according to claim 7, wherein the image forming body is a drum-shaped image forming body having a diameter of 60 mm to 160 mm. 9. The color image forming apparatus according to claim 7, wherein the transfer means is installed on the upstream side of the vertical line position above the horizontal line by 5 to 40 degrees. 10. The color image forming apparatus according to claim 7, wherein the cleaning unit is installed 10 degrees to 50 degrees downstream of the vertical line position above the horizontal line. 11. The color image according to claim 7, wherein the image forming body is housed in a cartridge together with the plurality of charging units and the plurality of developing units, and is detachably attached to the main body of the apparatus. Forming equipment.