JPS6015663A - Transfer device - Google Patents

Abstract

PURPOSE:To prevent dropout in the stage of plural times of transfer and to obtain an image having good color balance by providing a projecting member for maintaining a spacing to at least a part of a photosensitive drum and a transfer drum. CONSTITUTION:A photosensitive drum 10 having a photoconductive layer such as an Se layer has spacer rings 12 so that always a specified spacing is provided between said drum and a transfer drum 26. Said rings are provided on the outside circumference outer than the image forming part G of the drum 10. The drum 26 is provided to shafts 27 and is so constituted that the circumferential surface thereof contacts with the rings 12 of the drum 10. The drum 26 has the same diameter as the diameter of the drum 10 and 1:1 speed ratio. The transfer is accomplished while the contact of the powder image on the drum 10 with the transfer material P on the drum 26 is prevented by the rings 12 in the above- mentioned way. The spacer rings may be provided on the outside circumference at both ends outer than the part of the drum 26 where the material P is held.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a transfer device applied to a transfer type electronic copying machine.
In particular, it relates to a transfer device in a color copying machine.

Conventional configuration and its problems In transfer type color copying machines, in order to superimpose the powder image formed on the photoreceptor onto the transfer material, the transfer material is wrapped around the transfer drum and transferred directly to the photoreceptor. A method is used in which transfer is performed three or four times by bringing the material into contact with the material.

The above method is based on the bias roller transfer method and can be used effectively, especially in color copying machines, because alignment can be easily achieved during transfer, but multiple transfers can be performed on the same transfer material. Because of this, there were problems as shown below.

FIG. 1 shows a sectional view of the main parts of a transfer device in a conventional color copying machine, and its structure and operation will be explained below.

A conventional transfer device includes a transfer drum 2 provided opposite to a photoreceptor drum 1, transfer material gripping means 3 provided on the circumference of this transfer drum 2, transfer material separation means 4, transfer bias voltage application means 6, Conventionally, the powder image on the photoreceptor drum 1 is transferred onto the transfer material P using a transfer device as described above, which is composed of a guide plate 6 and a transfer material transport mechanism (not shown), to obtain a multicolor image. In this case, the transfer material P is passed along the circumference of the transfer drum 2 through the guide plate 6, and then gripped onto the transfer drum 2 by the transfer material gripping means 3.

Further, the transfer material conveying mechanism transports the transfer material P to the transfer position A in synchronization with the powder image on the photoreceptor drum 1, and simultaneously applies a bias voltage for transfer when it comes into contact with the powder image on the photoreceptor drum 1. The means 6 applies a bias voltage between the photosensitive drum 1 and the transfer drum 2 to transfer the powder image on the photosensitive drum 1 onto the transfer material P.

In the same way, transfer is performed 3 to 4 times for each color, and the transfer material P
A multicolored image is formed on top.

Thereafter, this transfer material P is separated from the transfer drum 2 by the transfer material separating means 4 and conveyed to the next step.

As described above, the conventional transfer device is configured, but when performing multiple transfers, the transfer material P is brought into direct contact with the powder image on the photoreceptor drum 1. When a powder image that has been transferred with a weak adhesion force due to the bias charge is attached to the photoreceptor drum 1 during the next transfer, or when an image such as a character is transferred, the center portion of the powder image may be removed. A phenomenon of so-called hollow areas that are not transferred occurs, making it difficult to obtain a high-quality color image with good color balance.

In addition, in order to improve the disadvantages of Nire et al., instead of using the conventional bias roller method for transfer, a corona charger 7' is installed on the back of the transfer drum 2' as shown in FIG. Although a corona transfer type transfer device has been proposed, it does not fully solve the above-mentioned drawbacks, and it also has the drawback that alignment during transfer becomes difficult.

OBJECTS OF THE INVENTION The present invention solves the problems in the conventional transfer device, and by providing a simple gap maintaining member between the photoreceptor and the transfer drum, hollowing out occurs even during multiple transfers. It is an object of the present invention to provide a transfer device capable of obtaining high-quality color images without any blemishes.

Structure of the Invention The present invention relates to a transfer device for a color copying machine, and includes a photoreceptor, a transfer drum that rotates in synchronization with the photoreceptor and holds and conveys a transfer material for transferring an image on the photoreceptor; The transfer device includes a gap holding member that is in contact with the photoconductor and the transfer drum and keeps a constant gap between the photoconductor and the transfer drum at all times, and the gap between the image on the photoconductor and the transfer drum is By performing transfer with a constant gap between the transfer material and the transfer material, it is possible to obtain a high-quality color image free from hollow defects.

DESCRIPTION OF THE EMBODIMENTS FIG. 3 shows a schematic cross-section of a transfer device according to an embodiment of the present invention and a color copying machine to which the transfer device is applied. Further, FIG. 4 is a perspective view showing the main parts of a transfer loading device in an embodiment of the present invention, and the structure thereof will be explained below based on the drawings.

10 is a photosensitive drum for electrophotography having a photoconductive layer such as a selenium layer Se or a cadmium sulfide layer CdS;
1, and rotates in the direction of arrow B.

The spacer ring 12 always provides a constant gap between the photoreceptor drum 1o and a transfer drum 26, which will be described later, and as shown in FIG. It is integrally provided on the outer periphery of both ends.

Reference numeral 13 denotes a document table glass on which the original is placed.

First scanning mirror 14. The second scanning mirror 16 performs original scanning, and is configured to operate at a speed ratio of 1:%.

The light source 16 illuminates the original and is integrated with the first scanning mirror.

Lens system 17. Third scanning mirror 18. 4th scanning mirror 1
9 transfers the original reflected light image to the photoreceptor drum 1.
It focuses on 0 and is fixed to the main body. The color separation filter 20 is rotatably supported on a shaft 21,
20a, 20b, 2 corresponding to 3 colors (R, G, B)
It consists of a filter of 0c. A slit 22 is provided in the main body so as to be adjustable. Corona charger 23
is for uniformly charging the photosensitive drum 10, and is provided so as to face the photosensitive drum 1o.

The developing devices 24 include four developing devices 24a, 24b, and 24c for cyan, magenta, yellow, and black.

24d, and is provided so as to face the photosensitive drum 10.

The cleaning blade 26 cleans the photosensitive drum 1 after the transfer.
It removes unnecessary toner remaining on the photosensitive drum 1o, and is provided so as to come into contact with the circumference of the photosensitive drum 1o.

The transfer drum 26 is rotatably supported on a shaft 27, and
By a biasing means (not shown), it is slidably biased together with the shaft 27 toward the photoconductor drum 10, so that its circumferential surface comes into contact with the spacer ring 12 that is integrally provided on the photoconductor drum 1o. It is configured.

Further, the transfer drum 26 has the same diameter as the photosensitive drum 1o, and has a diameter of 1:
The photoreceptor drum 1o is connected to the photoreceptor drum 1o by gears at a speed ratio of 1, and is configured to rotate in synchronization with the photoreceptor drum 1o. The grit gripping device 2B is for gripping the transfer material P, and is provided integrally with the transfer drum 26. The separation claw 29 separates the transferred transfer material P from the transfer drum 26, and is rotatably provided on the shaft 3o, and is linked to the grip release operation of the gripper device 28.
The tip portion thereof is configured to come into contact with the transfer drum 26.

A cassette 31 stores the transfer material P.

The paper feed row 232 separates and sends out the transfer material P in the cassette 31 one by one, and is supported by a shaft 33 so as to rotate in the direction of arrow C. It is configured so that it always comes into contact with P. Further, the paper feed roller 32 rotates in the direction of arrow C only when sending the transfer material P out from the cassette 31, so that the rear end of the transfer material P reaches the paper feed roller 3.
It is configured to stop after passing through 2.

The timing rollers 34 and 35 further convey the transfer material P sent out by the paper feed roller 232 to the transfer drum 26, and are in a stopped state when the paper feed roller 32 is rotating, and after the paper feed roller 32 has stopped, the photosensitive drum It is configured to rotate in the arrow and E directions in synchronization with the image above.

The fixing device 36 completely fixes the toner on the transfer material P, and is composed of a heat roller 37, a rubber roller 38, and a heater 39.

The paper ejecting rollers 4o and 41 are for sending out the transfer material P after a series of copying processes to the outside of the main body, and the shaft 42 and the shaft 4
3 is rotatably supported.

Reference numeral 44 denotes a paper discharge tray that receives the discharged transfer material P.

46, 4θ, and 47.48 are guide plates fixed to the main body, respectively.

Regarding the transfer device of this embodiment configured as described above,
The operation will be explained below. The original on the document platen glass 13 is illuminated by a light source 16, and the reflected light is scanned by a first scanning mirror 14 and a second scanning mirror 15. The first scanning mirror 14 and the second scanning mirror 15 move at a speed ratio of 1:3A, thereby scanning the original while always keeping the optical length of the first half of the lens system 17 constant. The light image passes through the lens system 17 and passes through the color separation filter 20.
The color separation filter 2o converts the optical image into three colors (R
, G, B) corresponding to 20a.

20b, 20c, and the color-separated optical image is sent to the third scanning mirror 18. and fourth scanning mirror 1
9. Further, the image passes through the slit 22 and is formed on the photoreceptor drum 10.

The photosensitive drum 1o is charged by a corona charger 23,
Next, an electrostatic latent image is obtained while irradiating the color-separated optical image. The image is developed by a yellow developer 24C) and visualized. After development, the powder image on the photosensitive drum 10 reaches the transfer section A.

When a copying operation is started, the uppermost transfer material P in the cassette 31 is sent out by the paper feed roller 32 as the photosensitive drum 10 rotates, passes through the guide plate 46, hits the timing roller 34 or 35, and stops instantaneously.

Thereafter, the transfer material P sent by the timing rollers 34 and 35 passes through a guide plate 46, is gripped by a gripper device 28 provided on the transfer drum 26, and is gripped by a powder image on the photosensitive drum 1o together with the transfer drum 26. sent in sync with.

Thereafter, the transfer material P on the transfer drum 26 reaches the transfer section A. In the transfer section A, the transfer material P on the transfer drum 26 and the powder image on the photoreceptor drum 10 are always kept apart from each other by a spacer ring 12, and when the transfer material P comes to the transfer section A, When a bias voltage is applied between the photoreceptor drum 10 and the transfer drum 26 by a transfer bias voltage applying means (not shown), the powder image on the photoreceptor drum 1o is transferred to the transfer material P on the transfer drum 26. Flying towards and transcribing,
A yellow powder image is formed on the transfer material P.

In the above manner, for example, the transfer material P to which the yellow powder image has been transferred can be used to transfer other red and green filters 20a,
The powder image on the photosensitive drum 1o, which has been sequentially exposed and developed (cyan and magenta) using the photoreceptor drum 20b, is transferred to form a multicolor image.

At this time, in this embodiment, since transfer is not performed by bringing the transfer material P into contact with the powder image on the photoreceptor drum 1o, when the transfer is performed multiple times, the previous powder image is transferred to the next powder image. There is no possibility that the toner may adhere to the photoreceptor drum 10 and the transfer will not be carried out satisfactorily.

The gap between the powder image on the photoreceptor drum 10 and the transfer material P on the transfer drum 26 is 20 μm to 100 μm when there is no powder image.
Experimental results have shown that m is preferable in terms of image quality.

That is, the open ocean of the spacer ring 12 is the outer surface of the photosensitive drum 10.
It is desirable that the outer diameter of the transfer material P be larger than the outer diameter of 40 μm to 200 μm + the paper thickness of the transfer material P.

Thereafter, the transfer material P on which the multicolor image has been formed is separated from the transfer drum 26 by releasing the grip of the gripper device 28 and at the same time operating the separation claw 29, and fixing the powder image on the transfer material P by the fixing device 36. It will be established.

Further, the transfer material P is discharged onto a paper discharge tray 44 by paper discharge rollers 40 and 41.

As described above, according to this embodiment, the spacer ring 12 is provided and the powder image on the photoreceptor drum 10 and the transfer material P on the transfer drum 26 are transferred without contacting each other, so that hollowing is prevented. You can get good quality color images without color.

A second embodiment of the present invention will be described below with reference to the drawings. 5 and 6 are perspective views showing the main parts of a transfer device in a second embodiment of the present invention. Components similar to those in the first embodiment are designated by the same numbers as in the first embodiment.

In FIG. 5, the difference from the first embodiment is that spacer rings 12 are provided on the outer circumference of both ends of the transfer drum 26 outside the transfer material P gripping portion, and the circumferential surface of the photoreceptor drum 1o. The transfer drum 26 is urged toward the photosensitive drum 1o so that the spacer ring comes into contact with the photosensitive drum 1o, thereby performing the transfer.

Also, in FIG. 6, the difference from the first embodiment is that spacer rings 49 and 5o are arranged on the outer periphery of both ends of the photoreceptor drum 1° outside the image forming portion and on the outside of the transfer material P gripping portion of the transfer drum 26. The transfer drum 26 is urged on the photosensitive drum 1o (IIllK) so that the spacer ring 6o on the transfer drum 26 comes into contact with the spacer ring 49 on the photosensitive drum 1o. Spacer'
) 7g 49 and 50 to create an appropriate gap (207z
m to 10100p, and is configured to perform transcription.

In addition, in the embodiment shown in FIGS. 6 and 6,
The configuration and operations not described are the same as those in the first embodiment.

As described above, according to this embodiment, the spacer ring 12 is provided on the transfer drum 26, and the spacer rings 49 and 6o are provided on both the photosensitive drum 1o and the transfer drum 26, so that the first embodiment is improved. It is possible to obtain a similar effect, and even after multiple transfers, it is possible to obtain a high-quality color image without hollowing out.

In the first and second embodiments, the spacer ring 12 is provided integrally with the photosensitive drum 1o and the transfer drum, but it goes without saying that the spacer ring 12 may be provided as a single unit.

Effects of the Invention As described above, the transfer device of the present invention includes a photoconductor, a transfer drum that rotates in synchronization with the photoconductor and holds and conveys a transfer material for transferring an image on the photoconductor, and the photoconductor. and a gap holding member that is in contact with the transfer drum and keeps a constant gap between the photoreceptor and the transfer drum at all times, and the gap holding member allows the image on the photoreceptor to be separated from the transfer material on the transfer drum. By performing transfer with a constant gap between This eliminates the phenomenon of hollow areas due to insufficient transfer, and it is possible to obtain high-quality color images with well-balanced colors, which has a great practical effect.

[Brief explanation of drawings]

1 and 2 are schematic cross-sectional views of a conventional transfer device, FIG. 3 is a cross-sectional view of a transfer device according to an embodiment of the present invention and a color copying machine to which the transfer device is applied, and FIG. 4 is a cross-sectional view of the same transfer device. FIGS. 3 and 6 are perspective views showing the main parts of a transfer device in other embodiments of the present invention. 1o...Photosensitive drum, 12...Spacer ring, 13...Original table glass, 17...
...Lens system, 2o...Color separation filter, 2
3...Corona charger, 24...Developer, 26...Transfer drum, 28...Gripper device, 29...Separation Nails, 32...
・Paper feed roller, 34.36...Timing roller, 36...Fuser. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
Figure 5

Claims (2)

[Claims] (1) A photoconductor, a transfer drum that rotates in synchronization with the photoconductor and holds and conveys a transfer material that transfers the image on the photoconductor, and a transfer drum that comes into contact with the photoconductor and the transfer drum and that rotates in synchronization with the photoconductor. and a gap holding member that maintains a constant gap between the transfer drum and the transfer drum. (2) The transfer device according to claim 1, wherein at least a portion of the photoreceptor and the transfer drum is provided with a gap holding member that protrudes from the photoreceptor surface or the transfer drum transfer surface.