JPH03171073A - Color image forming device - Google Patents

Abstract

PURPOSE:To prevent an electrostatic latent image on a surface of a photosensitive body from blurring due to a variation in load of a rotating transfer drum by driving the photosensitive body drum and the transfer drum by independent driving paths. CONSTITUTION:A first driving force transmitting mechanism 71 which transmits driving power to the transfer drum 34, and a second driving power transmitting mechanism 72 which transmits driving power to the photosensitive body 30 are connected to a driving source 70, in a state where they are independent of each other. In this case, the first driving force transmitting mechanism 71 and the second driving force transmitting mechanism 72 have their gear ratio, etc., set so that the transfer drum 34 and the photosensitive body drum 30 are rotated synchronized to each other. Therefore, the transfer drum 34 and the photosensitive body 30 can be individually driven by the first driving force transmitting mechanism 71 and the second driving force transmitting mechanism 72. Thus, the load variation of the transfer drum 34 can be controlled from being transmitted to the photosensitive body 30.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a color image forming apparatus, and more specifically, by rotating a sheet of paper wound around a transfer drum multiple times together with the transfer drum, photosensitive The present invention relates to a color image forming apparatus that transfers a toner image of each color of a document formed on a body onto a sheet of paper.

BACKGROUND ART Conventionally, color image forming apparatuses such as color copying machines and color printers that form color images on paper using electrostatic electrophotography have been provided.

FIG. 4 is a schematic view of the main parts of the above-mentioned color image forming apparatus, which visualizes the color-separated image into a toner image around a photoreceptor 90 onto which the color-separated image of the original is projected. A developing device 91 and a transfer drum 92 that winds the paper P and brings the paper P into contact with the photoreceptor 90 are provided.
On the other hand, a paper feed section 94 is provided that supplies paper P one by one via a paper transport path 93. Further, inside the transfer drum 92, there is a transfer charger 95 that transfers the toner image on the photoreceptor 90 onto the paper P, and a separation charger 9 that separates the paper P to which the toner image has been transferred from the photoreceptor 90.
6 is provided. Further, a peeling claw 98 is provided close to a predetermined position on the outer periphery of the transfer drum 92 to peel off the paper P on which transfer has been completed from the transfer drum 92 and guide it to the paper conveyance belt 97. A fixing device 99 for fixing the toner image transferred to the paper P is provided on the side.

In the color image forming apparatus configured as described above, the developing device 9
1 uses toner that has a complementary color relationship with the color separation image of the original. It is stored in a plurality of developing devices 91a, and each developing device 91a has a
It is selectively brought close to the photoreceptor 90 according to the color separation image of the original. Furthermore, a clip claw 92a is provided at a predetermined portion of the outer periphery of the transfer drum 92 to clip the leading end of the paper P conveyed through the paper conveyance path 93.

According to the color image forming apparatus described above, each time the paper P wound around the transfer drum 92 is rotated together with the transfer drum 92 and brought into contact with the photoreceptor 90, a toner image for each original color is transferred onto the paper P. can be done. Finally, the paper P on which the toner image has been transferred is peeled off from the transfer drum 92 by a peeling claw 98, and guided to nine fixing devices by a paper conveyance belt 97, and the toner image is transferred to the paper P.
By fixing the image on the original, a color image corresponding to the original can be obtained.

FIG. 5 is a schematic diagram showing a drive mechanism for the photoreceptor 90 and the transfer drum 92, and as shown in the figure, the photoreceptor 90
The transfer drums 92 and 92 are configured to rotate synchronously by gears Gl and G2 that are rotatably provided at their respective ends.

The photoreceptor 90 and the transfer drum 92 are driven by a drive gear G3 that is engaged with a gear G1 on the photoreceptor 90 side. Further, the transfer drum 92 is configured to be rotatable around a fulcrum O by a cam mechanism so as to be able to move toward and away from the photoreceptor 90. , is slightly separated from the photoreceptor 90, and is pressed against the photoreceptor 90 at the same time that the paper P is clipped by the clip claw 92a of the transfer drum 92.

The clip claw 92g is opened and closed by a cam (not shown) fixedly disposed inside the transfer drum 92.

Problems to be Solved by the Invention> In the color image forming apparatus having the above structure, the clip claw 92a engages with the cam fixedly disposed inside the transfer drum 92, and the engagement is released. When the paper P is clipped and unclipped by the clip claw 92a, the rotating transfer drum 92 is subjected to a load change, and this load change is applied to the photosensitive material via the gears Gl and G2. transmitted to the body 90. However, in the color image forming apparatus, at the same time that the paper P is clipped by the clipping claw 92a, the exposure operation of the original by the optical system is started, and the transfer drum 92 or the photoreceptor 9
Pressed to 0. Furthermore, when separating the paper P from the transfer drum 92, the transfer drum 92 is in pressure contact with the photoreceptor 90. Therefore, due to the above load fluctuation,
There is a problem in that the electrostatic latent image on the surface of the photoreceptor 90 tends to be blurred, and this pre-printing causes color shift in the image printed on the paper.

This invention has been made in view of the above problems, and provides a color image forming apparatus that can suppress blurring of an electrostatic latent image on the surface of a photoreceptor due to load fluctuations on a rotating transfer drum. The purpose is to provide

Means for Solving the Problems> In order to achieve the above object, the color image forming apparatus of the present invention has a color image forming apparatus that rotates a sheet of paper wound around a transfer drum multiple times together with the transfer drum, so that images formed on a photoconductor are In a color image forming apparatus that transfers a toner image for each color of an original onto paper, a first drum transmits driving force to a transfer drum.
The power transmission mechanism and the second power transmission mechanism that transmits the driving force to the photoconductor are connected to the drive source in a state where they are independent from each other.〉 Color image formation with the above configuration. According to the apparatus, the transfer drum and the photoreceptor can be driven individually by the first power transmission mechanism and the second power transmission mechanism, so that load fluctuations on the transfer drum are prevented from being transmitted to the photoreceptor. Can be suppressed.

Example Hereinafter, embodiments will be described in detail with reference to the accompanying drawings showing examples.

FIG. 2 is a schematic diagram showing the internal structure of a color copying machine as a color image forming apparatus of the present invention, in which an optical system 2 for exposing and scanning a document is provided in the upper part of the apparatus main body 1, and below it, An image forming section 3 that forms a copy image on the paper P and a paper transport section 4 that transports the paper P are provided, and the toner image formed on the paper P is fixed in the middle of the paper transport section 4. A fixing device 5 is provided for this purpose.

The optical system 2 includes a light emitter 21, a reflector 22, and a lens 23.
, a color separation filter 24, etc., and by scanning and exposing the document multiple times, a color separation image (
For example, a q-minute image of three primary colors) can be projected for each original color onto a photoreceptor drum 30 of an image forming section 3, which will be described later.

The image forming section 3 also includes a charger 31, a charger 31,
Blank lamp 32, developing device 33, transfer drum 34,
A cleaner 35 and a static elimination lamp 36 are arranged in this order, and a transfer charger 37 and a separation charger 38 are provided inside the transfer drum 34. The charger 31 charges the photosensitive drum 30. After uniformly charging and removing unnecessary charges using the blank lamp 32, a color-separated image of the document is formed on the photosensitive drum 30 to form an electrostatic latent image, and the developing device 33 develops the image into a toner image. The toner image is transferred by the transfer charger 37 onto the paper P wound around the transfer drum 34, and after the residual toner is collected by the cleaner 35, the residual charge can be removed by the static elimination lamp 36.

The developing device 33 has a plurality of developing devices 33b attached to a rotating body 33a that is rotated by a predetermined angle at predetermined timings, and each developing device 33b stores toner of a different color. By arranging a developing device 33b containing toner of a complementary color to the electrostatic latent image formed on the photoreceptor drum 30 to face the photoreceptor drum 30, the electrostatic latent image for each color of the original is generated. It can be visualized into a toner image.

A clip claw 34a for clipping the leading end of the paper P is provided at a predetermined portion of the outer periphery of the transfer drum 34. The clip claw 34a is rotatably provided around an axis parallel to the axis of the transfer drum 34, and is biased to rotate in a direction in which it comes into pressure contact with the surface of the transfer drum 34 by a spring (not shown). The leading edge of the paper P can be inserted between the front surface of the paper P and the surface of the paper P to be clipped. Further, when the paper P is clipped and unclipped, the clip claw 34g is rotated in a direction away from the transfer drum 34 against the urging force of the spring by the cam mechanism 6 disposed inside the transfer drum 34. Operated (see Figure 3)
.

The cam mechanism 6 has a clip claw 3 when clipping the paper P.
4a in the direction away from the transfer drum 34, and a clip claw 34 to release the creases and bulges on the paper P when all toner image transfer is completed.
2nd to rotate a in the direction away from the transfer drum 34;
cam member 62 and a drive unit 63 that alternately displaces each cam member 61.62 in the radial direction of the transfer drum 34 at predetermined timings, and the clip claw 34a moves each cam member 61.62. The transfer drum 34 is rotated by engaging with the cam members 61 and 62 while being displaced outward in the radial direction of the transfer drum 34 . The drive unit 63 includes an operating lever 63b that can swing around a shaft 63a, and an operating lever 63b that can swing around a shaft 63a.
By alternately swinging the operating lever 63b, each cam member 61, 62 is rotated about the shaft 63d in the radial direction of the transfer drum 34. It can be displaced. Note that the clip claw 34a is engaged with the cam members 61 and 62 via an engagement lever 34c formed integrally therewith.

Further, the unclipped paper P is placed on the transfer drum 34 at a predetermined position close to the outer periphery of the transfer drum 34.
A peeling claw 34b is provided for peeling off the sheet. The peeling claw 34b is rotationally driven by a solenoid or the like so that it can move toward or away from the transfer drum 34.

The peeling claw 34b is attached to the paper P on which the toner image has been transferred.
It also functions as a guide member that guides the transport belt 42 to be described later.

The transfer drum 34 is provided with a push-up claw 34d coaxially with the clip claw 34a for pushing up the leading edge of the paper P toward the outside of the transfer drum 34 when the paper is separated from the transfer drum 34. There is. This push-up claw 3
4d is rotated by the second cam member 62.

Furthermore, the paper conveyance unit 4 includes a registration roller 4l that feeds the paper P supplied from the paper feed cassette 12 or the manual paper feed unit 13 to the clip claw 34a of the transfer drum 34;
A conveyor belt 42 feeds the paper P peeled from the transfer drum 34 to the fixing device 5, and the paper P that has passed through the fixing device 5
A discharge port 43 for discharging the water onto the pedestal 14 is provided.

The fixing device llf5 includes a heating roller 51 and a pressure roller 5.
2 are placed facing each other, and these heating rollers 51 and pressure rollers 52,
The paper P on which the toner image has been transferred can be held and conveyed to the paper discharge side.

Note that the heating roller 51 is constantly driven to rotate while being heated to a predetermined temperature by a heating means such as a heater provided inside.

In the color copying machine configured as described above, the transfer drum 34 is supported by three arms that are rotatable about a fulcrum 0 so that the transfer drum 34 can be moved away from the photosensitive drum 30 (see FIG. 1). The transfer drum 34 is slightly separated from the photosensitive drum 30 when the paper P is wound around the transfer drum 34 and when the developing device 33b facing the transfer drum 34 is switched to another developing device 33b. In addition, the transfer drum 34 is separated from the photosensitive drum 30 by a large distance so that when a paper jam occurs in the image forming section 3, the jam can be easily cleared.

FIG. 1 is a schematic diagram showing the drive system of the transfer drum 34 and the photosensitive drum 30. Both drums 34 and 30 have a first power transmission mechanism 71 and a second power transmission mechanism 72, respectively.
The driving forces are transmitted independently from each other. The first power transmission mechanism 71 transmits the driving force of the drive source 70 to the first gear 7 meshed with the drive gear 70a of the drive source 70.
1a, a second gear 7lb meshed with the first gear 71g, and a third gear 71C provided at one end of the transfer drum 34 and meshed with the second gear 7lb. The signal is transmitted to the drum 34. Further, the second power transmission mechanism 72 transmits the driving force of the drive source 70 to a first sprocket 72a that is provided to be able to rotate integrally with the upper Z drive gear 70a, and to this first sprocket 72a via a chain 72b. A second sprocket 72c connected to
A fourth gear 72d is provided to be rotatable integrally with the second subrocket 72c, and a fifth gear 72e is provided at one end of the photoreceptor drum 30 and meshed with the fourth gear 72d. The image is transmitted to the photo drum 30 through the photosensitive drum 30. The gear ratios and the like of the first power transmission mechanism 71 and the second power transmission mechanism 72 are set so that the transfer drum 34 and the photosensitive drum 30 are rotated in synchronization with each other. In this way, the transfer drum 34 and the photosensitive drum 30 are connected to the first power transmission mechanism 71 and the second power transmission mechanism, respectively.
Since the transfer drum 34 is driven via the power transmission mechanism 72, load fluctuations on the transfer drum 34 caused by the clip claws 34a of the transfer drum 34 engaging with the cam members 61, 62 are transmitted to the photoreceptor drum 30. It is possible to suppress the

Note that the rotation center 0 of the arm 39 that supports the transfer drum 34 is set coaxially with the first gear 71a, and the second gear 71b is supported by the three arms. For this reason, the transfer drum 34 is connected to the photoreceptor drum 3.
When moving away from 0, the transfer drum 34 revolves around the rotation center O and simultaneously rotates, and when the transfer drum 34 is brought close to the photosensitive drum 30 again, it rotates in the opposite direction to the original position. Return. Therefore, the transfer drum 3
Even if the transfer drum 34 and the photoreceptor drum 30 are moved away from the photoreceptor drum 30, there is no risk that the relative positions of the transfer drum 34 and the photoreceptor drum 30 in the circumferential direction will shift.

The present invention is not limited to the above-mentioned embodiments, and various design changes can be made, for example, by configuring the second power transmission mechanism 72 entirely with gears. <Effects of the Invention> As described above, According to the color image forming apparatus of the present invention, since the photoreceptor drum and the transfer drum are driven by independent drive paths, load fluctuations of the rotating transfer drum are hardly transmitted to the photoreceptor drum. This has the unique effect of suppressing blurring of the electrostatic latent image on the surface of the photoreceptor due to this.

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram showing an embodiment of a color image forming apparatus of the present invention, Fig. 2 is a schematic diagram showing a drive system for a transfer drum and a photosensitive drum, and Fig. 3 is a schematic diagram showing an opening/closing mechanism of a lip claw. 4 is a schematic diagram showing a conventional example, and FIG. 5 is a schematic diagram showing a conventional drive system for a transfer drum and a photosensitive drum. 30... Photosensitive drum, 34... Transfer tram, 71
...First power transmission mechanism, 72...Second power transmission mechanism, P...Paper.

Claims (1)

[Claims] 1. Roll the paper wrapped around the transfer drum. By rotating it multiple times with the photographic drum. Therefore, the toner of each original color formed on the photoreceptor is Color image formation that transfers a color image to paper In the device, driving force is transmitted to the transfer drum. The first power transmission mechanism that reaches the photoconductor a second power transmission mechanism that transmits driving force; are used as a driving source in a state where they are independent of each other. A color painting characterized by being connected Image forming device.