JP3103994B2 - Developing unit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a means for preventing a developer from being scattered in a developing device installed in a color image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art In general, a color image forming apparatus includes a yellow developing device for storing yellow toner in order from the top in a rotating direction of a photosensitive drum as an image carrier, and a magenta developing device for storing magenta toner. A cyan developing device for containing cyan toner and a black developing device for containing black toner face the peripheral surface of the photoreceptor drum and are installed at predetermined intervals different from the peripheral surface. Have been. Then, yellow, magenta, cyan, and black toners are sequentially superimposed on the electrostatic latent image formed on the peripheral surface of the photoreceptor drum and developed to form a required color image.

[0003]

As described above, each developing device is provided between the peripheral surface of the photoreceptor drum and the front end portion, which is a facing surface of each developing device for accommodating each color of yellow, magenta, cyan, and black. Different gaps are provided corresponding to the characteristics.

In the course of development, toner scatters from gaps at both ends of the developing device facing the peripheral surface of the photosensitive drum, and contaminates the image reading optical system and the writing optical system in the image forming apparatus. This has an adverse effect on the operation of the main gear and the developed color image.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a developing device capable of preventing toner from being scattered from both sides of the developing device facing the peripheral surface of the photosensitive drum. .

[0006]

This object is achieved by the following a, b
Achieved by any means.

[0007] (a) electrostatic latent image that will be formed on the image bearing member
Is developed with a different color toner to form a color image
Configured as in the developing device in the color <br/> over the image forming apparatus having at least three developing units, each developing unit
Is close to the peripheral surface of the image carrier and
Positioned along and to the distal end sides of the developing unit facing the peripheral surface of the image-forming-area of the image bearing member, it
It is flexible, and the strip of the developer scatter preventing member continuously
Developing device, characterized in that provided Te.

(B) In item a), the developing device is yellow
Contains toner, magenta toner, and cyan toner
Developing device, characterized in that it is a developing device.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a side sectional view showing an attached state of a developer scattering prevention member provided in the developing device of FIG. 1, a top view of FIG. 2, and a main structure of the developing device of FIG. This will be described with reference to a side sectional view showing the configuration of the color image forming apparatus shown in FIG. However, the present invention is not limited to this embodiment.

FIG. 4 is a sectional view showing a main structure of a copying machine as the color image forming apparatus 1. This copying machine is roughly divided into an image reading system A, a laser writing system unit B,
It comprises an image forming section C and a sheet feeding section E, and a color image is formed by the following process.

First, in a reading system A, an original set on a platen glass 11 is a halogen lamp mounted on a carriage 12 which slides in a horizontal direction of a scanning optical system 10.
Illuminated by 13. Mirrors 16 and 16a are attached to the movable mirror unit 15 in a V-shape. The mirrors 16 and 16a are also slid in the horizontal direction to read the light image of the original image in combination with the mirror 14 attached to the carriage 12. Department
Derived to 17.

The carriage 12 and the movable mirror unit 15 are driven via wires (both not shown) connected to a stepping motor, and are driven at V and 1/2 V, respectively.
At the same speed.

The image reading section 17 has a lens 18 and a color CCD 19 at an image forming position behind the lens 18. Color CCD19
Is used for color separation when an original on the platen glass 11 is read, and is composed of a 3-line CCD having a filter that passes red light, green light and blue light. The color signal that has been color-corrected according to the colors of the yellow (Y), magenta (M), cyan (C), and black (B) toners is input to a laser writing unit B that is an exposure unit.

In the laser writing unit B, a laser beam generated by a semiconductor laser (not shown)
An image carrier that is rotationally scanned by a polygon mirror 52 rotated by a drive motor 51, has an optical path bent by a mirror 54 via an fθ lens 53, and is uniformly charged to a predetermined charge by a charger 55 serving as a charging unit in advance. Is projected on the peripheral surface of the photosensitive drum 30 to form a bright line.

On the other hand, in the sub-scanning direction, the photosensitive drum 30
The index provided at the specific position is detected by a photo sensor (both not shown), and based on this detection signal, the modulation of the semiconductor laser by the image signal is started, and the main scanning direction is determined. When scanning is started, a laser beam is detected by an index sensor (neither is shown) in the main scanning direction, and the modulated laser beam scans the peripheral surface of the photosensitive drum 30. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive drum 30 by the main scanning by the laser beam and the sub-scanning by the rotation of the photosensitive drum 30. In the present embodiment, the latent image is developed by a yellow developing unit 6Y containing, for example, yellow (Y) toner (visualizing medium) among a plurality of developing units provided in parallel, and a photosensitive drum 30 is provided. A Y toner image is formed on the surface. The obtained toner image is transferred to the photosensitive drum 30.
While being held above, the sheet passes below the cleaning device 59 which is a cleaning means which is separated from the peripheral surface of the photoreceptor drum 30, and then enters the second color copy cycle.

That is, the photosensitive drum 30 on which the Y toner image has been formed is charged again by the charger 55, and then the second color signal output from the reading system A is input to the writing system unit B. Writing is performed on the surface of the photosensitive drum 30 in the same manner as in the case of the first color signal described above, and a latent image is formed. The latent image is a magenta developer 6M containing, for example, magenta (M) toner as the second color.
Developed by This M toner image is formed in the presence of the Y toner image already formed.

Similarly, the latent image formed by the third image signal is developed by a cyan developing device 6C containing cyan (C) toner, and after recharging, the latent image formed by the fourth image signal is changed to black. (B) The C toner image and the B toner image are superimposed on the peripheral surface of the photosensitive drum 30 by developing with the black developing device 6B containing the toner, and the color toner image is
Formed on 30 surfaces.

An AC or further DC bias is applied to the developing sleeves of these developing units 6Y, 6M, 6C and 6B, and reversal development (jumping development) is performed in a non-contact manner on the photosensitive drum 30 whose base is grounded. Is being done. A developing unit not related to development stops rotation of the developing sleeve and cuts a bias to be applied to prevent a toner image formed on the photosensitive drum 30 from being damaged, and to remove unnecessary toner from the latent image. Do not supply to.

The color toner image formed on the peripheral surface of the photosensitive drum 30 as described above is supplied from a paper supply unit E by a paper supply belt at a transfer pole 56 provided as a transfer means, and is supplied to the color roller by a timing roller. The image is transferred onto a recording sheet, which is a recording medium synchronized with the toner image. This transfer is performed by applying a high-voltage power supply having a polarity opposite to that of the toner by the transfer pole 56.

Thus, the recording paper on which the color toner image has been transferred is separated from the surface of the photosensitive drum 30 by the separation pole 57, and is conveyed to the belt fixing device 58 via the transport belt to fix the color toner image. After being fed, it is ejected.

On the other hand, after the transfer and separation of the color toner image onto the recording paper, the photosensitive drum 30 is further rotated clockwise, and the blade 59A of the cleaning device 59 is pressed against the photosensitive drum 30 to remove and clean the remaining toner. Done. After the cleaning is completed, the blade 59A is separated from the photosensitive drum 30 again, and a new color image forming process is started.

FIG. 3 shows a cross section of a main part of the yellow developing device 6Y. Reference numeral 20 denotes a developing device main body forming a housing of the developing device 6Y, 22 denotes a first stirring member, 23 denotes a second stirring member, and 24 denotes a second stirring member. Is a supply roller, 26 is a developing sleeve, 28 is a cylindrical rod which is a developer thin film forming means having rigidity for regulating the amount of the developer applied to the peripheral surface of the developing sleeve 26, and 28a is a conveying amount of the developer. A cylindrical plate 28, which is a spring plate for regulating, is pressed against the developing sleeve 26 with a constant load in a state where no developer is present. Reference numeral 27 denotes a scraper that cuts and cuts the developer, reference numeral 25 denotes a stirring partition plate, and reference numeral 21 denotes an upper lid integrally attached to the upper surface of the developing device main body.

The toner supplied to the yellow developing device 6Y is sufficiently stirred and mixed by the carrier by the second stirring member 23 rotating in the direction of the arrow and the first stirring member 22 rotating so as to overlap each other in the opposite direction. In addition, the developer D is sent to the developing sleeve 26 via the supply roller 24.

The first agitating member 22 and the second agitating member 23 are screw-shaped members having a left-handed helical angle rotating in opposite directions of arrows, and are conveyed to the back side by the thrust of the first agitating member 22. The toner and the carrier sequentially pass over the agitation partition plate 25 whose upper edge is inclined low in the depth direction of the drawing, and the second
A supply roller that moves to the stirring member 23 side, is conveyed to the near side of the drawing by the thrust, and is a uniform developer D that is frictionally charged by the mixing action of the toner and the carrier therebetween, and is sponge-shaped and rotates in the direction of the arrow. 24 adheres in a layer on the peripheral surface of the developing sleeve 26 which rotates clockwise as shown by the arrow.

The toner conveyed by the developing sleeve 26 is applied to the electrostatic latent image formed on the peripheral surface of the photosensitive drum 30 adjacent to the developing sleeve 26 at a predetermined gap with a predetermined gap. Is developed. The rotation of each of the first and second stirring members 22 and 23, the supply roller 24 and the developing sleeve 26 is transmitted to each other by a drive transmission mechanism mounted on a side surface of the developing device main body 20. Other developing unit 6M,
6C and 6B also operate with exactly the same configuration and function as the above-described yellow developing device 6Y.

The developer leakage preventing member provided in the developing device of the present invention is arranged as follows. As shown in FIGS. 1 and 2, the developing units 6Y, 6M, and 6C containing the toners of yellow, magenta, and cyan are arranged in a case 7 in order from the top and at a predetermined interval downward. The black developing device 6B accommodated in the case 7a is separately disposed below the case 7. As shown in the figure, each of the developing units 6Y, 6M, 6C, and 6B has a peripheral surface of the photosensitive drum 30 at an appropriate position at a front end facing the peripheral surface of the photosensitive drum 30 outside the image forming area. Abutting rollers 6a are provided for positioning the developing devices 6Y,
A pressing spring 8 acting in the direction of the photosensitive drum 30 is provided between each of the right side surfaces of 6M, 6C, 6B and each of the cases 7, 7a, and the photosensitive member is pressed by the pressing action of the spring 8 and the abutting roller 6a. The drum 30 is positioned and pressed against the peripheral surface of the drum 30 with a predetermined gap therebetween.

As shown in FIGS. 1 and 2, the photosensitive drum 30 is used to prevent the developer D and toner from being scattered to the outside from the gaps on both sides of the tip of each of the developing units 6Y, 6M, 6C and 6B. The developer scattering prevention member 9 is provided on both sides of the distal end of each of the developing devices 6Y, 6M, 6C in the case 7 facing the outer peripheral surface of the image forming area L (FIG. 2) so as not to interfere with the abutting rollers 6a. For example, by a double-sided tape or the like.
The developer scattering prevention member 9 has a thickness of about 2 mm and has a double structure of a member made of a flexible and elastic material such as maltprene and a member made of a high-density polyethylene material having excellent slidability. It is a belt-shaped member having.
Then, a high-density polyethylene material having good slidability is opposed to the peripheral surface of the photoreceptor drum 30, and the tip is bent and attached to both sides of the upper surface portion of the yellow developing device 6Y located at the uppermost position as shown in the figure. After being attached to both sides of the front end of each of the developing devices 6Y, 6M, 6C, the rear end is bent and attached to both sides of the bottom surface of the cyan developing device 6C. Therefore, each developing unit 6Y,
Both end portions of 6M and 6C are continuously attached in the vertical direction (FIG. 1) without any gap by a single elongated strip-shaped developer scattering prevention member 9.

Although the positions of the tips of the developing units 6Y, 6M, and 6C are different from each other, since the developer scattering preventing member 9 has flexibility, the developing devices 6Y, 6M, and 6C are affixed in an irregular shape at the tips. ing. The black developing unit 6B located at the lowermost position is also a single unit, but the developer scattering prevention member is adhered to both ends of the developing unit 6B by bending in the same manner as described above. ing. Although the black developing device 6B is separated and independent from the other developing devices 6Y, 6M, and 6C in terms of the specifications of the image forming apparatus, the black developing device 6B may be collectively housed in the case 7 without being separated. Of course, each one developer scattering prevention member 9
Will be pasted. Each of the developers 6Y, 6M, 6C, on which the developer scattering prevention member 9 is attached,
6B, the scattering prevention member 9 is about half 1 mm when pressed against the peripheral surface of the photosensitive drum 30 by the respective pressing springs 8.
The gap between the peripheral surface of the photosensitive drum 30 and both ends of each of the developing devices 6Y, 6M, 6B is completely closed by being compressed to the front and rear thickness.

Each of the developing units 6Y, 6M, 6 is provided by the developer scattering prevention member 9 extremely easily attached in this manner.
The developer D and the toner are prevented from being scattered from both sides of the front end portions of C and 6B, and a good color image is always formed on the peripheral surface of the photosensitive drum 30.

The present invention is applicable not only to the developing device of the color image forming apparatus but also to the developing device of the mono-black image forming apparatus.

[0031]

According to the present invention, the peripheral surface of the photosensitive drum of the color image forming apparatus and both sides of the leading end of each developing device are closed without gaps by the developer scattering prevention member which is extremely easily attached. 6M, 6C, and 6B were prevented from scattering the developer from both sides to the outside.

[Brief description of the drawings]

FIG. 1 is a side cross-sectional view showing an attached state of a developer scattering prevention member provided in a developing device according to one embodiment of the present invention.

FIG. 2 is a top view of the above.

FIG. 3 is a side sectional view showing a main configuration of the developing device.

FIG. 4 is a side sectional view illustrating a configuration of a color image forming apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color image forming apparatus 6Y Yellow developing device 6M Magenta developing device 6C Cyan developing device 6B Black developing device 7 Case 8 Press spring 9 Developer scattering prevention member 20 Developing device main body 26 Developing sleeve 30 Photoconductor drum D Developer

Claims (2)

(57) [Claims] 1. A latent electrostatic image that will be formed on the image bearing member, different
To develop a color image.
Construction was, in the developing device in the color image forming apparatus having at least three developing units, each developing device, before
Close to the peripheral surface of the image carrier and along the rotation direction
It is arranged, also, to the distal end sides of the developing unit facing the peripheral surface of the image-forming-area of the image bearing member, respectively, variable
Flexible, strip-shaped developer scattering prevention members are continuously provided
Developing device, characterized in that it is. 2. The developing device according to claim 1, wherein the developing device is a yellow toner, a magenta
The developing device according to claim 1, wherein the developing device stores toner and cyan toner .