JPH0535078A - Color electrophotographic device - Google Patents

Abstract

PURPOSE:To obtain an excellent image by preventing a vibration when a developing unit comes closer/leaves to/from a photosensitive body. CONSTITUTION:Large and small diameter parts and an inclined part connecting them, are provided on one of the photosensitive body 10 of the color electrophotographic device and the gap roller 23 of the developing unit 13. On the other hand, the gap roller 23 freely moves in the direction the roller shaft 22 of a developing roller 21 on the developing unit and a moving mechanism 29 moving the gap roller 23 is provided. Then, the photosensitive body 10 and the gap roller 23 are always abutted on the large or small diameter part, so that the developing unit 13 comes closer/leaves to/from the photosensitive body 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic system using a laser, such as a printer, a copying machine, and a facsimile (a system in which an image formed on a photoconductor is transferred to a sheet for recording).
Therefore, it can be applied to a color electrophotographic apparatus which records on paper. Specifically, a plurality of developing devices are arranged along the surface of the photoconductor and supported on the surface so as to be able to move back and forth, respectively, and those developing devices are appropriately and selectively brought close to the surface of the photoconductor, and the developing roller is attached to the surface. The present invention relates to a color electrophotographic apparatus which holds gaps between the developing roller and the surface of the photoconductor by pressing gap rollers at both ends of the roller of the roller.

[0002]

2. Description of the Related Art Conventionally, in this type of color electrophotographic apparatus,
A color image is obtained by performing development for each color on the photoconductor using a plurality of developing devices, superimposing images of the respective colors, and then transferring the images onto a sheet. At that time, the developing device that does not perform the development is separated from the surface of the photoconductor in order to avoid color mixture, and as shown in FIG.
Is biased in the direction opposite to the photoconductor 4 by a biasing means such as a spring 2, and a cam 3 is provided so as to project to the rear side of each developing device 1 to move back and forth to the photoconductor 4 and at the same time, in each developing device 1. As shown in FIG. 10, gap rollers 7 having a diameter slightly larger than the diameter of the developing roller 5 are provided at both ends of the roller shaft 6 of the developing roller 5. When developing, the developing device 1 is pushed toward the photoconductor 4 against the biasing force of the spring 2, and the gap roller 7
Is applied to the surface of the photoconductor 4 to maintain the gap between the developing roller 5 and the surface of the photoconductor 4, and when development is not performed, the developing device 1 is retracted from the photoconductor 4 by the urging force of the spring 2. The gap roller 7 was separated from the photoconductor 4.

[0003]

However, in such a conventional color electrophotographic apparatus, the gap roller 7 is brought into contact with the photoconductor 4 each time the developing device 1 moves toward and away from the photoconductor 4, and then Therefore, there is a disadvantage that the photosensitive member 4 is vibrated to cause color misregistration in the image.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to prevent vibration when the developing device moves toward and away from the photosensitive member and to obtain a clear image.

[0005]

Therefore, according to the present invention as set forth in claim 1, a plurality of developing devices 13 are arranged along the surface of the photoconductor 10 and arranged on the surface thereof, respectively, as shown in the following illustrated embodiment. Supports the rearward and backward movements of those developing devices 13
Is selectively and appropriately brought close to the surface of the photoconductor 10, and the gap rollers 23 at both ends of the roller shaft 22 of the developing roller 21 are pressed against the surface to bring the developing roller 21 and the photoconductor 10 into contact.
In the color electrophotographic apparatus that maintains a gap g with the surface of the photoconductor 10, the gap roller receiving portions 24 are provided at both ends of the photoconductor 10.
While a large diameter portion such as b and a small diameter portion such as the gap roller receiving portion 24a and an inclined portion 25 connecting them are provided, the gap roller 23 is movable in the direction of the roller axis 22 and the gap roller It is characterized in that a moving mechanism 29 for moving 23 is provided.

Further, according to the present invention described in claim 2, a plurality of developing devices 13 are arranged along the surface of the photoconductor 10 and supported on the surface so as to be able to move back and forth, for example, as in the following illustrated embodiment. The developing device 13 is appropriately and selectively brought close to the surface of the photoreceptor 10, and the gap rollers 23 at both ends of the roller shaft 22 of the developing roller 21 are pressed against the surface of the developing roller 21. In a color electrophotographic apparatus that holds a gap g between the surface and the surface of the photoconductor 10, the gap roller 23 is provided with a large diameter portion 23c, the small diameter portion 23d, and an inclined portion 23e connecting them, while The gap roller 23 is movable in the direction of the roller shaft 22, and a moving mechanism 29 for moving the gap roller 23 is provided.

[0007]

When the development is not performed, the gap roller 23 is moved in the direction of the roller shaft 22 through the inclined portion,
The developing device 13 is retracted from the photoconductor 10 by applying the large diameter portion of either the photoconductor 10 or the gap roller 23 to the other surface.

At the time of development, the gap roller 23 is moved in the direction of the roller shaft 22 through the inclined portion, and the photosensitive member 1 is moved.
The small diameter portion of either 0 or the gap roller 23 is applied to the other surface to approach the photoconductor 10, and the gap g between the surface of the developing roller 21 and the surface of the photoconductor 10 is maintained.

[0009]

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

FIG. 9 is a color diagram showing an embodiment of the present invention.
1 is a diagram showing a schematic configuration near a photoconductor of a laser printer. Reference numeral 10 in the figure denotes a photoconductor, and around the photoconductor 10, a charger 11, an optical writer 12, and a
A developing device 13, a transfer charger 14, a static eliminator 15, and a cleaning device 16 are arranged, and the developing device 13 is arranged in the order of developing devices 13a, 13b, 13c, 13d of yellow, red, blue and black.

The photoconductor 10 is rotationally driven in the direction of the arrow,
At that time, after charging the surface of the photoconductor 10 with the charger 11,
The optical writing device 12 provided on the upper portion irradiates, for example, laser light based on a yellow image signal to form an electrostatic latent image on the photoconductor 10. Then, the electrostatic latent image is transferred to the yellow developing device 13a.
To develop a yellow toner image on the photoconductor 10.
During this period, developing devices 13b-1 for red, blue, and black colors other than yellow
3c and 13d have retreated from the photoconductor 10. Then, after development with a yellow toner, the surface of the photoconductor 10 is destaticized by the destaticizer 15. Next, similarly to the formation of the yellow toner image, charging, exposure, development and charge elimination are repeated, and the red developing device 13 is used.
b, the blue developing device 13c and the black developing device 13d form respective toner images. After completion of all toner development, the transfer charger 14 electrostatically transfers the paper 17 conveyed to the lower side of the photoconductor 10. On the other hand, the toner remaining on the photoconductor 10 after the electrostatic transfer is removed by the cleaning device 16.

By the way, as shown in FIG. 1, the developing device 13 is biased toward the photoconductor 10 by a biasing means such as a spring 20. Gap rollers 23 are provided at both ends of the roller shaft 22 of the developing roller 21 so as to be movable in the direction of the roller shaft 22. In this gap roller 23, a flange portion 23a is formed at an end portion on the developing roller 21 side, and a flange portion 23b is formed at the other end portion. Further, a large diameter portion having a diameter larger than that of the photoconductor 10 is provided at both ends of the photoconductor 10 to form a gap roller receiving portion 24b. Both the gap roller receiving portion 24b and the photoconductor 10 are inclined portions 25.
Tie in. Further, the gap roller 23 is urged toward the developing roller 21 side by a spring 26 provided on the roller shaft 22, and the inner surface of the collar portion 23b of the gap roller 23 is driven in parallel with the developing roller 21. End cam 28 provided on shaft 27
The drive shaft 27, the spring 26 and the like constitute a moving mechanism 29 for the gap roller 23. Then, the gap roller 23 comes closest to the developing roller 21 side, the collar portion 23a contacts the surface of the photoconductor 10, and the gap roller 23 straddles the gap roller receiving portion 24b.
The gap g between the developing roller 21 and the surface of the photoconductor 10 is maintained.

When the development is not performed, the drive shaft 27 of the moving mechanism 29 is driven to rotate the end surface cam 28, as shown in FIG. Then, the end face cam 28 is attached to the collar portion 2.
3b, the other collar 23a rides on the inclined portion 25 and moves onto the gap roller receiving portion 24 to move the gap roller 23a.
Is the farthest position from the developing roller 21. Therefore, the developing device 13 is pushed in the direction opposite to the photoconductor 10 and causes color mixing in the image on the photoconductor with a predetermined distance L between the surface of the photoconductor 10 and the surface of the developing roller 21. Retreat to an empty position. When developing, the end surface cam 28 is rotated by driving the drive shaft 27 of the moving mechanism 29 to release the pressing of the gap roller 23, so that the gap roller 23 is moved toward the developing roller 21 side by the spring 26. It is pushed back to the state shown in FIG. Therefore, the collar portion 23a moves onto the photoconductor 10, and the gap g between the surface of the developing roller 21 and the surface of the photoconductor 10 is maintained.

FIG. 3 shows another embodiment, in which the photoconductor 10 is not provided with a large diameter portion and the gap roller 2 is provided.
3 comprises a large diameter portion 23c, a small diameter portion 23d and an inclined portion 23e connecting them. Then, the gap rollers 23 are brought into a state in which the small diameter portions 23d are opposed to each other, and the springs 26 urge the developing rollers 21 respectively. Also, the small diameter portion 2
The side surface of one end of the L-shaped lever 30 is brought into contact with the facing surface of 3d. In addition, both leverage-3
The other end portion of 0 is parallel to the upper and lower sides, and its side surfaces are opposed to each other, and rack teeth 31 are provided at the opposed portions to mesh with a pinion 32 provided on the main body of the developing device 13, so that the lever 30 and the pinion 32 are connected to each other. -A moving mechanism 29 for the gap roller 23 is constituted by a spring 26 or the like provided on the rotary shaft 22. Then, the small diameter portion 23d of the gap roller 23 is brought into contact with the photoconductor 10 so that the gap g between the surface of the developing roller 21 and the surface of the photoconductor 10 is maintained.

When the development is not performed, as shown in FIG. 4, the pinion 32 of the moving mechanism 29 is driven to move the lever 30 inward to move the gap roller 23 to the spring 2.
At 6, the pressing roller 21 is pushed toward the developing roller 21, and the contact portion of the gap roller 23 with the photoconductor 10 is moved from the small diameter portion 23d to the large diameter portion 23c through the inclined portion 23e. Then, the developing device 13 is pushed in the direction opposite to the photoconductor 10 and the image on the photoconductor having a predetermined space L between the surface of the photoconductor 10 and the surface of the developing roller 21 does not cause color mixing. Retreat to the position. Further, when developing, when the pinion 32 of the moving mechanism 29 is driven, the gap roller 23 is pushed against the developing roller 21 against the urging force of the spring 26, and the contact portion with the photoconductor 10 is contacted. From the large diameter portion 23c through the inclined portion 23e to the small diameter portion 23d
To the state shown in FIG. Therefore, the developing roller 21
A gap g between the surface of the photoconductor 10 and the surface of the photoconductor 10 is maintained.

FIG. 5 shows another embodiment, in which one end of the photoconductor 10 is provided with a small-diameter portion having the photoconductor 10 as a large-diameter portion, and the small-diameter gap roller receiving member is provided. A large-diameter portion having a small-diameter portion for the photoconductor 10 is provided at the other end, and this is used as a large-diameter gap roller receiving portion 24b. The small-diameter gap roller receiving portion 24a and the photoconductor 10 are connected to each other by the inclined portion 25, and the large-diameter gap roller receiving portion 24b and the photoconductor 10 are connected to each other by an inclined portion 25. A large-diameter gap roller 40a is provided at one end of the developing roller 21, and a small-diameter gap roller 40b is provided at the other end. Further, an eccentric cam 41 that comes into contact with one side surface of the developing device 13 is provided, and a spring 42 that biases the eccentric cam 41 toward the other side surface is provided.
Make up. Then, the eccentric cam 41 of the moving mechanism 29 is brought into contact with the developing device 13 at the maximum diameter portion, and the large diameter gap roller 4
0a is applied to the small-diameter gap roller receiving portion 24a, and the small-diameter gap roller 40b is applied to the photoconductor 10, and the developing roller is rotated.
The gap g between the surface of the roller 21 and the surface of the photoconductor 10 is maintained.

When the development is not performed, the eccentric cam 41 of the drive mechanism 29 is rotated so as to contact the developing device 13 at the minimum diameter portion as shown in FIG.
The urging force of 2 moves the developing device 13 in parallel with the photoconductor 10. Then, the small-diameter gap roller 40b becomes the inclined portion 25.
On the large-diameter gap roller receiving portion 24b, and the large-diameter gap roller 40a rides on the inclined portion 25 and moves on the photoconductor 10 to hit its surface. Therefore, the developing device 13 is pushed in the direction opposite to the photoconductor 10 and a predetermined gap L is formed between the surface of the developing roller 21 and the surface of the photoconductor 10.
And retreat to the position on the photoconductor 10 on which the color mixture does not occur. When developing, the eccentric cam 41 of the moving mechanism 29 is rotated and brought into contact with the developing device 13 at the maximum diameter portion, so that the developing device 13 resists the urging force of the spring 42 and reverses the above. Is pushed in the direction, and the large diameter gap roller 40
5a is moved to the small-diameter gap roller receiving portion 24a via the inclined portion 25, and the small-diameter gap roller 40b is moved to the photosensitive member 10 via the inclined portion 25 to obtain the state of FIG. Therefore,
A gap g between the surface of the developing roller 21 and the surface of the photoconductor 10 is maintained.

FIG. 7 shows still another embodiment, in which a circumferential groove 43 is provided at one end of the photoconductor 10 and the end portion divided by the circumferential groove 43 has the same diameter as the photoconductor 10. The gap roller receiving portion 24 of FIG. In addition, as described above, the large diameter portion 2
A gap roller 23 formed by 3c, a small diameter portion 23d, and an inclined portion 23e connecting them is provided so that the small diameter portion 23d faces the gap roller receiving portion 24 side. Then, the eccentric cam 41 of the moving mechanism 29 is brought into contact with the developing device 13 at the minimum diameter portion, and the large diameter portion 23c and the inclined portion 23e of the gap roller 23 on the side of the gap roller receiving portion 24 enter the circumferential groove 43,
The small diameter portion 23d contacts the gap roller receiving portion 24, and the small diameter portion 23d of the other gap roller 23 contacts the surface of the photoconductor 10. Then, the gap g between the surface of the developing roller 21 and the surface of the photoconductor 10 is maintained.

When the development is not performed, the eccentric cam 41 of the moving mechanism 29 is rotated as shown in FIG.
By contacting the developing device 13 at its maximum diameter portion, the developing device 13 resists the urging force of the spring 42 and the photosensitive member 1
Move parallel to 0. Therefore, one of the gap rollers 2
3 rides on the gap roller receiving portion 24 by its inclined portion 23e, and the other gap roller 23 also rides on the photosensitive member 10 in the same manner, and in each case, the large diameter portion 23c thereof is held on the gap roller receiving portion 24 and the photosensitive member 10. Apply on the surface of. Therefore, the developing device 13 is pushed in the direction opposite to the photoconductor 10 and causes a color mixture on the image on the photoconductor 10 with a predetermined distance L between the surface of the photoconductor 10 and the surface of the developing roller 21. Retreat to a position where it does not wake up. When developing, the moving mechanism 2
By rotating the eccentric cam 41 of No. 9 and bringing it into contact with the developing device 13 at the minimum diameter portion, the developing device 13 is pushed in the opposite direction by the urging force of the spring 42 and returns to the state of FIG. 7. Therefore, the gap g between the surface of the developing roller 21 and the surface of the photoconductor 10 is maintained.

[0020]

Therefore, according to the present invention, the developing device has a developing roller.
Since the gap roller provided in the lens always comes in contact with the photoconductor in a state of being applied to the photoconductor, the vibration of the photoconductor due to the withdrawal of the developing device is eliminated, and a beautiful image without color misregistration can be obtained.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a state at the time of development in an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a state during non-development.

FIG. 3 is a configuration diagram showing a state during development of another embodiment.

FIG. 4 is a configuration diagram showing a state of the embodiment of FIG. 3 during non-development.

FIG. 5 is a configuration diagram showing a state at the time of development of still another embodiment.

FIG. 6 is a configuration diagram showing a state of the embodiment of FIG. 5 during non-development.

FIG. 7 is a configuration diagram showing a state at the time of development of still another embodiment.

FIG. 8 is a configuration diagram showing a state of the embodiment of FIG. 7 during non-development.

FIG. 9 is a schematic configuration diagram in the vicinity of a photoconductor of the color laser printer of the present invention.

FIG. 10 is a perspective view showing a relationship between a developing roller of a conventional developing device and a photoconductor.

FIG. 11 is a schematic configuration diagram of a conventional example of a developing device.

[Explanation of symbols]

10 photoconductor 13 Developer 21 Development Roller 22 Roller axis 23 Gap Roll 23c Large diameter part 23d small diameter part 23e inclined part 24 Gap roller receiver 24a Gap roller receiving part (small diameter part) 24b Gap roller receiving part (large diameter part) 25 slope 29 Moving mechanism 40a Gap roller (large diameter part) 40b Gap roller (small diameter part)

[Procedure amendment]

[Submission date] October 17, 1991

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

[Figure 4]

[Figure 5]

[Figure 6]

[Figure 7]

[Figure 8]

[Figure 9]

[Figure 10]

FIG. 11

Claims (2)

[Claims] 1. A plurality of developing devices are arranged along the surface of a photoconductor and supported on the surface so as to be able to move back and forth, and the developing devices are appropriately and selectively brought close to the surface of the photoconductor to develop on the surface. In a color electrophotographic apparatus in which gap rollers at both ends of a roller axis of a roller are pressed to maintain a gap between the surface of the developing roller and the surface of the photoconductor, a large diameter is provided at both ends of the photoconductor. A color electrophotographic apparatus, which is provided with a portion, a small diameter portion, and an inclined portion that connects them, and which is provided with a moving mechanism that allows the gap roller to move in the roller axis direction and moves the gap roller. 2. A plurality of developing devices are arranged along a surface of a photoconductor and supported on the surface so as to be able to move back and forth, and the developing devices are appropriately and selectively brought close to the surface of the photoconductor to develop on the surface. In a color electrophotographic apparatus in which gap rollers at both ends of a roller of a roller are pressed to maintain a gap between the surface of the developing roller and the surface of the photoreceptor, a large diameter portion is provided on the gap roller. And a small-diameter portion and an inclined portion that connects the small-diameter portion and the small-diameter portion, while the gap roller is movable in the roller axis direction, and a moving mechanism for moving the gap roller is provided.