JPS6015662A - Transfer device - Google Patents

Abstract

PURPOSE:To enable transfer always at a specified spacing irrespectively of the thickness of a transfer material and to obtain a color image free from dropout development, etc. by bringing a photosensitive body and a drum for conveying and transferring the transfer material into contact with each other. CONSTITUTION:A transfer drum 26 which has the same diameter as the diameter of a photosensitive drum 10 and rotates at the same speed as the speed of said drum is provided on shafts 26 and has spacer rings 28 on the shafts 26 at both ends. The rings 28 are provided via elastic members 39 to rings 29. The width L1 thereof is made shorter by (L2-L1)divided by 2=2-5mm. than the width L2 at which the transfer material is held. The rings 28 are kept stopped as a detaining pawl 31 engages with a turning plate 32 in the stage of holding transfer paper P on the drum 25 and in the stage of separating the paper P therefrom but said pawl is disengaged from the plate 32 and the rings rotate together with the drum 25 when the position D where the transfer material is held on the drum 25 and the position E of the rings 28 coincide in the stage of transfer. Then the rings are sandwiched between the drum 10 and the paper P of the drum 25 in the transfer position A and the spacing between the powder image on the drum 10 and the paper on the drum 25 is thus maintained always constant.

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, the present invention 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. 3 to 4 times
A method of performing multiple transfers is used.

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 it is difficult to perform multiple transfers 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 photosensitive drum 1, a transfer material gripping means 3 provided on the circumference of the transfer drum 20, a transfer material separation means 4, a transfer bias voltage application means 5, and a guide. It consisted of a plate 6 and a transfer material conveyance mechanism (not shown).

Conventionally, when transferring the powder image on the photoreceptor drum 1 onto the transfer material P using a transfer device as described above to obtain a multicolor image, the transfer material P is passed along the two circumferences of the transfer drum through the guide plate 6. After that, the transfer material gripping means 3 grips the transfer material onto the transfer drum 2.

Furthermore, the transfer material conveyance mechanism transports the transfer material P to the transfer position A in synchronization with the powder image on the photoreceptor drum 1, and at the same time brings the transfer material P into contact with the powder image on the photoreceptor drum 1, the transfer bias is applied. A bias voltage is applied between the photoreceptor drum 1 and the transfer drum 2 by the voltage application means 5, and the powder image on the photoreceptor drum 1 is transferred 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. The first powder image transferred with a weak adhesion force of electric charges may adhere to the photoreceptor drum 1 during the next transfer and be removed, or when an image such as characters is transferred, the center of the powder image may be removed. A so-called hollow phenomenon occurs in which a portion is not transferred, making it difficult to obtain a high-quality color image with well-balanced color.

In order to improve these drawbacks, instead of the conventional bias roller method for transfer, a corona charger 7' is provided on the back of the transfer drum 2' as shown in FIG. 2, and the transfer is performed by corona discharge. Although a corona transfer type transfer device has been proposed, it does not fully solve the above-mentioned drawbacks, and furthermore, it has the disadvantage that alignment becomes difficult during transfer.

OBJECT OF THE INVENTION The present invention solves the problems with the conventional transfer device.It is possible to obtain a high-quality color image without hollowing even after multiple transfers, and it is possible to obtain a high-quality color image without hollowing out or the like even after multiple transfers. It is an object of the present invention to provide a transfer device that can perform good transfer without any problems.

Structure of the Invention The present invention relates to a transfer device for a color copying machine, and 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; The transfer device includes a gap holding member that faces the photoconductor and covers at least a portion of the transfer material, and connects the photoconductor and the transfer drum via the gap maintenance member and the transfer material. By bringing them into contact with each other, it is possible to transfer images with a constant gap between the image on the photoreceptor and the transfer material on the transfer drum regardless of the paper thickness of the transfer material. It is possible to obtain a high-quality color image without any phenomena.

DESCRIPTION OF EMBODIMENTS FIG. 3 is a schematic cross-sectional view of a transfer device according to an embodiment of the present invention and a color copying machine to which the same is applied. FIGS. 4 and 5 are cross-sectional views showing the main parts of a transfer device in an embodiment of the present invention. FIG. 6 is a longitudinal cross-sectional view of the main parts of a transfer device in one embodiment of the present invention, and the structure thereof will be explained below based on the drawings.

In FIG. 3, 10 is an electrophotographic photosensitive drum having a photoconductive layer such as a selenium layer (Ss) or a cadmium sulfide layer (CdS), and is rotatably supported on a shaft 11. Rotate in the direction of arrow B. Reference numeral 12 denotes a document table glass on which the original is placed. The first scanning mirror 13 and the second scanning mirror 14 perform original scanning, and are configured to operate at a speed ratio of 1:%, respectively. The light source 15 illuminates the original and is integrated with the first scanning mirror. The lens system 16, the third scanning mirror 17, and the fourth scanning mirror 18 each form an original reflected light image on the photoreceptor drum 1o.
Fixed to the main body.

The color separation filter 19 is rotatably supported on a shaft 2o, and has a color separation filter 19a corresponding to three colors (R, G, B).

It is composed of filters 19b and 19c.

21 is a slit that is adjustable on the main body.
The corona charger 22 uniformly charges the photoreceptor drum 10, and is provided so as to face the photoreceptor drum 1o.

The developing device 23 is composed of four developing devices 23a, 23b, 23C, and 23d for cyan, magenta, yellow, and plaque, and is provided so as to face the photosensitive drum 10. The cleaning blade 24 is for removing unnecessary toner remaining on the photoreceptor drum 1o after the transfer. It is rotatably supported by a shaft 26, and is slidably biased together with the shaft 26 toward the photosensitive drum 1o by biasing means (not shown).

Further, the transfer drum 26 has the same diameter as the photosensitive drum 10 and has a diameter of 1:
It is gear-coupled with the photoreceptor drum 1o at a speed ratio of 1, and -
It is configured to rotate in the C direction in synchronization with the photosensitive drum 10.

The gripper device 27 grips the transfer material P,
It is provided integrally with the transfer drum 25.

As shown in FIG. 6, the spacer ring 28 is provided on a rotating ring 29 rotatably supported by a shaft 26 at both ends of the transfer drum 25 via an elastic member 30 (for example, polyurethane foam).

Spacer rings 2 provided at both ends of the transfer drum 25
The width L1 between 8 and 8 is the transfer material holding width L2 on the transfer drum 25.
On the other hand, the length is set to be 2-Ll (□=2 to 5 points) short enough to not affect the image.

Further, a locking pawl 31 is provided on the spacer ring 28, and the locking pawl 31 engages with a rotating plate 32 rotatably provided on the main body.

The spacer ring 28 shown above is attached to the transfer drum 25.
When gripping the transfer material P on top and when separating the transfer material P, which will be described later, the locking claw 31 on the spacer ring 28 engages with the rotating plate 32 and is in the position shown in FIG. 4. Although it is stopped, during transfer, as shown in FIG. 5, when the transfer material gripping position of the transfer drum 26 and the E position of the spacer ring 28 match, the rotation plate 32 is released and the transfer starts. drum 25
The photosensitive drum 1 rotates together with the photosensitive drum 1 and is held between the photosensitive drum 10 and the transfer material P on the transfer drum 25 at the transfer position A.
The gap between the powder image on the transfer drum 26 and the transfer material on the transfer drum 26 is kept constant at all times.

The separation claw 33 transfers the transferred transfer material P to the transfer drum 25.
It is rotatably provided on the shaft 34, and is configured such that its tip comes into contact with the circumference of the transfer drum 25 in conjunction with the grip release operation of the grit holder 27. ing.

A cassette 35 stores the transfer material P.

The paper feed roller 36 separates and sends out the transfer material P in the cassette 35 one by one, and is supported by a shaft 37 so as to rotate in the direction of arrow F. It is configured so that it is always in contact with the Further, the paper feed roller 36 rotates in the direction of the arrow F only when feeding the transfer material P from the cassette 35, so that the rear end of the transfer material P reaches the paper feed roller 36.
It is configured to stop after passing through.

The timing rollers 38 and 39 further convey the transfer material P sent out by the paper feed roller 36 to the transfer drum 25, and are in a stopped state when the paper feed roller 36 is rotating, and after the paper feed roller 36 has stopped, the photosensitive drum 1o is stopped. It is configured to rotate in the directions of arrows G and H in synchronization with the image above.

The paper conveyance unit) 40 conveys the transfer material P separated from the transfer drum 25 to a fixing device 46, which will be described later, and includes a roller 43 and a roller 44 rotatably supported on shafts 41 and 42. The conveyor belt 45 is configured to rotate in one direction as the rollers 43 and 44 rotate.

The fixing device 46 completely fixes and fixes the toner on the transfer material P, and includes a heat roller 47 and a rubber roller 48.
and a heater 49.

The paper discharge rollers 5o and 51 are for sending out the transfer material P that has completed a series of copying processes to the outside of the main body, and the shafts 52 and 6
Reference numeral 054, which is rotatably supported by the shaft 3, is a paper discharge tray that receives the discharged transfer material P. 55.56.57.5
8 is a guide plate fixed to the main body. 0 Regarding the transfer device of this embodiment configured as above,
The operation will be explained below.

The original on the document platen glass 12 is illuminated by a light source 16, and the reflected light is scanned by a first scanning mirror 13 and a second scanning mirror 14. The first scanning mirror 13 and the second scanning mirror 14 move at a speed ratio of 1:3A, thereby scanning the original while keeping the optical length of the first half of the lens system 16 constant. The light image passes through the lens system 16 and passes through the color separation filter 1.
9, and this color separation filter 19 separates the light image into three colors (
19a corresponding to R, G, B).

19b or 19c, and the color-separated optical image is sent to the third scanning mirror 17 and the fourth scanning mirror 18.
, further passes through the slit 21 and forms an image on the photosensitive drum 1o.

The photosensitive drum 10 is charged by a corona charger 22,
Next, an electrostatic latent image is obtained while irradiating the color-separated optical image.

The electrostatic latent image on the photosensitive drum 10 is then developed by a developer corresponding to the color separation filter (for example, a yellow developer 23c for the blue filter 19c) and made visible. After development, the powder image formed on the photoreceptor drum 10 reaches the transfer section A.

When a copying operation is started, the uppermost transfer material P in the cassette 36 is transferred to the paper feeder 36 as the photosensitive drum 1o rotates.
It is sent out by the guide plate 55, hits the timing roller 38 or 39, and stops instantaneously.

Thereafter, the transfer material P sent by the timing rollers 38 and 39 passes through a guide plate 66 and is gripped by a gripper device 27 provided on the transfer drum 26.

The gripped transfer material P is then conveyed together with the transfer drum 25, passes through the transfer section A, and reaches position E of the spacer ring 28. Here, the transfer material P passes through the transfer section A, but at this time, no powder image has yet been formed on the photoreceptor drum 1o, and the powder image is not transferred.

When the tip of the transfer material P reaches the E position, that is, the D position, the rotary lever 32 that had been locking the spacer ring 28 until then comes off the locking claw 31 formed on the spacer ring 28, and the spacer ring 28 , together with the transfer material P held on the transfer drums 25 and 26, start rotating when the above position and the E position are aligned. At this time, the spacer ring 28 is provided on the transfer drum 25 via the elastic member 3o, and its diameter is the same as that of the transfer drum 25.
Since the diameter of the transfer material P is larger than the diameter of the elastic member 3o by the thickness of the elastic member 3o, the transfer material P is smoothly wound around the transfer drum 26 without coming into contact with the spacer ring 28. Thereafter, the transfer material P and the spacer ring 2 reach the transfer section A together with the transfer drum 25.

At this time, a powder image has already been formed on the photoreceptor drum 1o, and the transfer material P that has arrived at the transfer section A is spaced a certain distance from the powder image on the photoreceptor drum 10 by the spacer ring 2, which has been rotating together. Since the distance P is narrower than the width L2, the transfer part on the transfer drum 26, at this time, the spacer ring 2
8 and the transfer material P are held between the transfer drum 26 and the photoreceptor drum 1o, so that the elastic member 3o is bent and are in perfect contact with each other.

In this state, transfer bias voltage applying means (not shown)
When a bias voltage is applied between the photoreceptor drum 1o and the transfer drum 26, the powder image on the photoreceptor drum 1o is transferred in flight toward the transfer material P on the transfer drum 26, and the powder image is transferred to the transfer material P. formed on top.

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,
20b, the powder image on the photosensitive drum 1o, which has been sequentially exposed and developed (cyan and magenta), is transferred to form a multicolor image. In this embodiment, when a multicolor image is formed, the transfer material P is not drawn and transferred onto the powder image on the photoreceptor drum 10, so that during multiple transfers, the previously transferred powder There is no possibility that the image will adhere to the photoreceptor drum 10 again during the next powder image transfer and the transfer will not be performed sufficiently. According to experiments, the most preferable image quality could be obtained when the gap with P, that is, the thickness of the spacer ring was set to 20 μm to 100 μm.

The transfer material P on the transfer drum 26 on which the multicolor image has been formed is further sent together with the spacer ring 28, and the spacer ring 28 is stopped by the rotating plate 32 on the way and stopped at the position before transfer, and the transfer material P is transferred to the transfer drum Z. The upper transfer material P reaches the separation section and is separated from the transfer drum 26 by the separation claw 33.

The separated transfer material P is then sent by a paper transport unit 40, passes through a guide plate 57, and reaches a fixing device 46, where the powder image on the transfer material P is fixed. Further, the transfer material P is discharged onto a paper discharge tray 64 by paper discharge rollers 6o and 61.

As described above, according to this embodiment, the powder image on the photosensitive drum 1o and the transfer material P do not come into direct contact with each other, but the spacer ring 28 maintains a constant gap between the powder image and the transfer material P. Since the image is transferred while maintaining the image quality, it is possible to obtain a high-quality color image with no hollow defects.

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 faces and covers a part of the transfer material, the photoreceptor and the transfer drum are brought into contact with each other via the gap holding member and the transfer material, and the gap member By performing transfer by always maintaining a constant gap between the image on the photoreceptor and the transfer material on the transfer drum, regardless of the paper thickness of the transfer material, it is possible to perform transfer even during multiple transfers. In addition, the previous powder image transferred onto the transfer material will not adhere to the photoreceptor and be removed during the next powder image transfer, and the phenomenon of hollowing out due to insufficient turning will not occur. It is possible to obtain high-quality color images with well-balanced colors, which has great practical effects. Further, since the distance between the transfer material and the photoreceptor can be kept constant regardless of the thickness of the transfer material, good transfer can be performed.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic cross-sectional views of a conventional transfer device;
FIG. 4 is a sectional view of a transfer device according to an embodiment of the present invention and a color copying machine to which the same is applied. FIG. 5 is a cross-sectional view showing the main parts of the transfer device, and FIG. 6 is a cross-sectional view of the main parts of the transfer device in the longitudinal direction. 10...Photosensitive drum, 12...Original table glass, 16...Lens system, 19...
・Color separation filter, 22...Corona charger, 2
3...Developer, 25...Transfer drum,
27... Gripper device, 28... Spacer ring, 3o... Elastic member, 33...
... Separation claw, 36 ... Paper feed roller, S8, 3
9...Mark/timing-roller, 4o...Paper conveyance unit, 46...Fixer. Fig. 4 1θ Fig. 6/θ 5

Claims (1)

[Scope of Claims] 0) 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 a transfer drum that faces the photoconductor and that A transfer device comprising: a gap holding member that covers a part of the transfer material; and the photoreceptor and the transfer drum are brought into contact with each other via the gap holding member and the transfer material. (2) The transfer device according to claim 1, wherein gap holding members are provided at both ends of the transfer drum at intervals smaller than the width of the transfer material. (3) The transfer device according to claim 2, wherein the spacing member is constituted by an annular body having a diameter larger than the diameter of the transfer drum. (4) The transfer device according to claim 1, wherein the gap holding member is attached to the transfer drum via an elastic body.