JPH0511642A - Transfer device - Google Patents

Abstract

PURPOSE:To obtain high transfer efficiency and to prevent the failure and skipping of a transfer by using a contact type electrifier, and electrifying the opposite surface of a transfer material carrier while a transfer material pressurizing a photosensitive drum from the opposite face of the transfer material carrier. CONSTITUTION:In the contact part of the photosensitive drum 1 and the transfer material P, the electrifying roller 3 of a contact electrifier is rotated while the transfer material carrier 2 is pressed on the photosensitive drum 1 from the inner periphery of the carrier 2 to obtain the contact, so that a toner image T on the photosensitive drum 1 comes into contact with the transfer material P with proper pressure. this case the electrifying roller 3 positively electrifies the inner periphery of the transfer carrier 2 to form a transfer electric field. The negatively electrified toner image T on the photosensitive drum 1 is transferred and held on the transfer material P on a transfer part. Thus, the contact state of the toner image T on the photosensitive drum 1 and the transfer material P is stabilized, and uniform contact is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device used in an electrophotographic device or an electrostatic recording device such as a copying machine, a printer, a facsimile, etc., and in particular, it transfers toner images of a plurality of colors onto a transfer material in sequence. The present invention relates to a transfer device suitable for multiple transfer.

[0002]

2. Description of the Related Art As a method for forming a full-color image on a transfer material such as paper, there is known an electrophotographic method in which a toner image is formed on a photosensitive drum and a toner image is transferred on a transfer material for a predetermined color. There is.

An example of a transfer device in this type of electrophotography will be described with reference to FIG. As shown in FIG. 9, this transfer device includes a transfer drum 14 in which a transfer material carrier 2 made of a dielectric sheet such as plastic capable of holding an electric charge is wound around a transfer drum frame (not shown). The transfer drum 14 closely faces and opposes the photosensitive drum 1 at a transfer portion having a predetermined nip width. The transfer material carrier 2 carries a transfer material P on its outer peripheral surface and conveys the transfer material P to a transfer portion while rotating. In the transfer section, the pressing sheet 5 provided on the inner peripheral surface side of the transfer material carrier
While pressing the back surface of the transfer material carrier 2 with 2, the pressing sheet 5
An electrostatic field is formed by charging the inner peripheral surface of the transfer material carrier 2 with a corona charger 50 provided in the vicinity of 2. This corona charger 50 is a non-contact type charger,
A high voltage power supply 51 is connected to this charger. Due to this electrostatic field, the toner image T on the photosensitive drum 1 charged to a predetermined polarity is transferred to the transfer material P.

As described above, the transfer device using the transfer material carrier made of the dielectric sheet has a charging charge passing through the transfer material and is transferred onto the photoconductor drum like a transfer device in which a normal transfer material is directly charged. Since the toner image is not reversely charged, the transfer efficiency is high, and by controlling the charge amount of the transfer material carrier, it is possible to easily perform the transfer control during multiple transfer.

However, in a transfer device using a transfer material carrier composed of a dielectric sheet, the thickness of the dielectric sheet used is 150 μm in order to prevent peeling discharge that occurs when the transfer material leaves the photosensitive drum after transfer. It must be thinned to the following extent. This is 150 μm
This is because the electrostatic capacity becomes smaller and the charging potential becomes higher when the value exceeds. When such a thin sheet is used as the transfer material carrier, deformation is likely to occur when it is wound around the transfer drum frame. In addition, due to the design of the transfer device, in order to perform corona charging on the transfer material carrier corresponding to the transfer portion, the pressing sheet can be arranged only on a part of the upstream side of the transfer nip, so the nip width is narrow. Therefore, there is a problem that the transfer material and the photosensitive drum cannot be sufficiently contacted with each other, and there is a problem that partial transfer failure or transfer omission occurs.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. It uses a transfer material carrying sheet, has a high transfer efficiency, and is free from transfer defects and transfer omissions. An object of the present invention is to provide a transfer device that can obtain a uniform image.

[0007]

The transfer device of the present invention is a transfer device having a sheet-shaped transfer material carrier that carries a transfer agent and rotationally moves to convey the transfer agent to a transfer portion on the image carrier. The transfer material carrying body while pressing the image carrying body from the second surface of the transfer material carrying body through the material carrying means and the transfer material carried on the first surface of the transfer material carrying body. And a contact charging means for charging the second surface of the.

As a sheet-shaped transfer material carrier, for example,
A charge-retaining high-resistance dielectric sheet made of polyethylene terephthalate, polyimide, polycarbonate, polytetrafluoroethylene (Teflon), or polyvinyl chloride can be used.

As the contact charging means, a sheet-shaped transfer material carrier and a charging means capable of uniformly pressing the transfer material on the photosensitive member,
For example, a contact charger having a roller shape, a brush shape, a roller brush shape, or the like can be used.

[0010]

That is, in the transfer device of the present invention, the transfer material carried on the sheet-shaped transfer material carrier is exposed from the opposite surface of the transfer material carrier by using the contact type charger in the transfer part. While pressing against the body drum, the opposite surface of the transfer material carrier is charged. When this transfer device is used, the contact state between the toner image on the photosensitive drum and the transfer material is stabilized. In this way, the transfer material and the toner image are brought into uniform contact with each other in the transfer portion, so that no transfer failure or transfer omission occurs.
Further, since the transfer material carrier is charged, the charge does not pass through the transfer material to reversely charge the toner on the photosensitive drum.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic sectional view of a transfer portion of a transfer device according to the present invention. In the figure, a photosensitive drum 1 which is an image bearing member has a photosensitive layer 1b provided on the surface of an Al drum 1a which is grounded, and the photosensitive drum 1 has a negative image formed by a known image forming process. A toner image T charged with polarity is formed and rotates in the direction of the arrow.
On the other hand, a transfer material carrier 2 made of a dielectric sheet wound around a transfer drum frame (not shown) carries and fixes the transfer material P, and is in contact with the photosensitive drum 1 with a predetermined nip width. .. The transfer material carrier 2 is rotationally moved so as to have a constant circumferential speed with the photosensitive drum 1 as the transfer drum frame is rotated.

At the contact portion between the photosensitive drum 1 and the transfer material P, a charging roller 3 which is a contact charger is arranged in the transfer drum frame, and the charging roller 3 is on the photosensitive drum 1. The transfer material carrier 2 is rotated in the direction of the arrow while being pressed against the photosensitive drum from the inner peripheral surface thereof so that the toner image T and the transfer material P come into contact with each other at an appropriate pressure. The charging roller 3 is made of an elastic layer 3b made of conductive onset comedones urethane core metal 3a and a conductive urethane rubber layer provided on the surface thereof, the ² per 1cm between the metal core 3a and the surface layer 3c The resistance is about 10 ⁶ Ω. A bias power source 4 is connected to the core metal 3a, and a positive polarity DC voltage is applied from the bias power source 4 to the photosensitive layer 3b through the core metal 3a.

The charging roller 3 is a moving transfer material carrier 2.
While being pressed against the photosensitive drum from the inner peripheral surface side, the inner peripheral surface of the transfer material carrier 2 is charged with a positive polarity to form a transfer electric field. The negatively charged toner image T on the photosensitive drum 1 is transferred and held on the transfer material P at the transfer portion.

Next, the case where the present invention is applied to an electrophotographic color recording apparatus will be described.

FIG. 2 is a schematic configuration diagram showing an example of a color recording transfer device according to the present invention. In the figure, a well-known corona charger 11 is provided around the photosensitive drum 10, a laser optical system 12 for irradiating the photosensitive drum 10 with a laser beam 17 via mirrors 24 and 25, a developing device 13, and a transfer drum 14. A cleaner 15 made of a fur brush and a charge eliminating lamp 16 are arranged. The developing device 13 includes a black developing device 13a, a yellow developing device 13b, a magenta developing device 13c, and a cyan developing device 13d. The electrostatic latent image on the photoconductor drum 10 is selected and developed at appropriate times. ..

The transfer drum 14 has a transfer material carrier 2 made of a PET (polyethylene terephthalate) film having a thickness of 100 μm and stretched on a transfer drum frame body (not shown) connected by a connecting member 16. ,
A gripper 17 provided on the connecting member 16 for holding the tip of the transfer material P carried on the transfer material carrier 2, a charging roller 3 similar to that shown in FIG. 1, and carrying the transfer material after a predetermined number of times of transfer. Before the transfer material P is separated from the body 2, a static eliminator 18 and a separation claw 19 for discharging the transfer material P and the transfer material carrying body 2 are provided.

A transfer material (paper) P is stored in the cassette 27, picked up by a paper feed roller 26, and fed to the transfer drum 14 by a pair of registration rollers 23 in a timely manner. On the other hand, the transfer material P after transfer separated from the transfer material carrier 2 by the separation claw 19 is conveyed by the conveyor belt 20, and then the heat roller fixing device 2
1, the toner image on the transfer material P is fixed, and the tray 2
It is discharged to 2.

In the color recording apparatus using the transfer device having the above-mentioned configuration, charging, exposure, development, transfer, cleaning and charge removal of the photosensitive member are repeated for each color of the photosensitive drum once. After the transfer material P is fed to the transfer material 14, the transfer drum 1 is transferred the number of times corresponding to a predetermined number of colors (selected from black, yellow, magenta, and cyan).
4 is rotated to perform multiple transfer, and after the transfer is completed, the transfer material carrier 2 is discharged and the transfer material P is separated.

Using the color recording apparatus shown in FIG. 2 described above, multiple transfer of three colors was performed in the order of yellow, magenta, and cyan. FIG. 3 shows a graph showing the transfer efficiency with respect to the applied voltage of the charging roller at this time, that is, the transfer characteristic. From the figure, it can be seen that extremely high transfer efficiency can be obtained by sequentially increasing the voltage applied to the charging roller 3 with the number of times of transfer. This indicates that in the case of multiple transfer, the amount of toner transferred to the transfer material increases each time the transfer is repeated, so that it is possible to transfer more efficiently by increasing the applied voltage accordingly. .. In the obtained transfer image, partial transfer failure, transfer omission, etc. did not occur at all in all three colors.

As the contact charger 3, various examples other than the embodiment shown in FIG. 1 can be cited. 4 to 6
A modified example of the contact charging means is shown in FIG. For example, as shown in FIG. 4, a charging roller having a conductive rubber 3d provided on the surface of a core metal 3a, and as shown in FIG. 5, a fixing layer 3e made of conductive rubber provided on the surface of the core metal 3a. Examples of the charging brush roller include a conductive brush made of rayon or the like containing carbon in the fixed layer 3e, and a fixed charging brush made of a conductive brush fixed to a holder 3g as shown in FIG.

As described above, the contact charger used in the transfer device of the present invention has appropriate elasticity and appropriate electrical resistance,
Any charger may be used as long as it can uniformly and sufficiently press the transfer material and the transfer material bearing member against the photoreceptor.

FIG. 7 is a view showing the schematic arrangement of a color recording transfer device using a transfer belt. In the figure, the transfer material carrier 2 made of a dielectric sheet is an annular belt which is circulated by a pair of drive rollers 29 and 30 and rotates in the direction of the arrow. On the upper flat surface of the transfer material carrier 2, four process units 100a, 100b, 10
0c and 100d are sequentially arranged. 100a is black, 100b is yellow, 100c is magenta, and 100d is cyan. The four process units 100a, 100b, 100c and 100d have the same configuration, and the corona chargers 31a, 31b, 31c are provided around the photoconductor drums 30a, 30b, 30c and 30d which rotate in the directions of the arrows. And 31d, laser optical systems 32a, 32b, 3 for irradiating these photosensitive drums with laser beams 33a, 33b, 33c and 33d.
2c and 32d, developing units 34a, 34b, 34c and 3
4d, transfer belt 50, cleaner 35 composed of a blade
a, 35b, 35c and 35d, static elimination lamps 36a, 3
6b, 36c and 36d are arranged. Developing unit 34
Black, yellow, magenta, and cyan developers are contained in a, 34b, 34c, and 34d, respectively.

Inside the transfer material carrier 2, four contact type charging rollers 3a, 3b corresponding to each process unit,
3c and 3d are four photosensitive drums 30a, 30b,
30c and 30d are provided so as to face each other with the transfer material carrier 2 in between and to be pressed against each other. The charging roller charges the back surface of the transfer material carrier 2 in contact with the transfer portion, which is the contact portion.

Further, on the downstream side of each process unit,
Separation static eliminator 25 for eliminating static electricity on the sheet P, and transfer material carrier static eliminator 2 for eliminating static electricity on the transfer material carrier 2 after the sheet P is separated.
8 are provided. The transfer material P separated from the transfer material carrier 2 is conveyed to the heat roller fixing device 21, the toner image on the transfer material P is fixed, and the transfer material P is discharged to the tray 22.

A transfer material (paper) P is stored in a cassette 27 provided on the upstream side of each process unit, picked up by a paper feed roller 26, and transferred by a pair of registration rollers 23 at a timing. It is fed to 2.

In the color recording apparatus having a plurality of transfer portions having the above-described structure, toner images are sequentially formed on the photosensitive drums of the process units provided for each color, and the toner images are passed once through the paper. In addition, since multiple transfer is sequentially performed, there is an advantage that high-speed color storage can be performed. By applying the transfer device of the present invention to such a color recording device, transfer unevenness and transfer omission do not occur in each transfer image for each color.

FIG. 8 shows an example of a monochromatic recording apparatus according to the present invention. The transfer material carrier 2 made of a dielectric sheet is
It is an annular belt that is circulated by the pair of drive rollers 29 and 30 and rotates in the direction of the arrow. A photoconductor 40 is provided on the upper flat surface of the transfer material carrier 2 and rotates in the direction of the arrow in accordance with the rotational speed of the transfer material carrier. A cleaner 45, a discharge lamp 46, a corona charger 41, and a developing device 44 are provided on the photoconductor 40. Also,
A contact type charging roller 3 is provided inside the transfer material carrier 2 so as to oppose and press the photoconductor 40 with the transfer material carrier 2 interposed therebetween. In part, the back surface of the transfer material carrier 2 is charged while being in contact with it.

On the rotating transfer material carrier 2, a cassette 27 is provided on the upstream side of the photoconductor 40, and the transfer material (paper) P is stored in the cassette 27 and picked up by the paper feed roller 26. The pair of registration rollers 23 feed the transfer material carrier 2 at a proper timing. Further, on the downstream side of the photoconductor 40, there are provided a separation static eliminator 25 for neutralizing the paper P and a transfer material carrier static eliminator 28 for neutralizing the transfer material carrier 2 after the paper P is separated. The transfer material P separated from the transfer material carrier 2 is
The toner image on the transfer material P is fixed by being conveyed to the heat roller fixing device 21, and is discharged to the tray 22.

When single-color transfer was performed using the single-color recording apparatus having the above-mentioned structure, no uneven transfer and no transfer omission occurred.

[0031]

As is clear from the above description, according to the present invention, the transfer material and the toner image can be surely and uniformly contacted with each other, so that good transfer can be efficiently carried out without uneven transfer and missing transfer. You can Further, since the dielectric sheet is used as a transfer material carrier, an excellent color recording apparatus suitable for multiple transfer can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a transfer section of a transfer device of the present invention.

FIG. 2 is a schematic configuration diagram showing an example of a transfer device of the present invention.

3 is a graph showing transfer efficiency with respect to applied voltage in the apparatus of FIG.

FIG. 4 is a diagram showing a modification of the contact charger according to the present invention.

FIG. 5 is a diagram showing a modification of the contact charger according to the present invention.

FIG. 6 is a diagram showing a modified example of the contact charger according to the present invention.

FIG. 7 is a diagram showing an embodiment of a fixing device of the present invention.

FIG. 8 is a diagram showing another embodiment of the fixing device of the present invention.

FIG. 9 is a schematic configuration diagram of a conventional transfer device. 1 ... Photoconductor drum (image carrier), T ... Toner image, 2 ... Transfer material carrier, P ... Transfer material, 3 ... Contact charger.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshihiro Kasai 70 Yanagimachi, Saiwai-ku, Kawasaki-shi, Kanagawa Toshiba Yanagimachi Factory

Claims (1)

Claim: What is claimed is: 1. A transfer material carrying unit having a sheet-shaped transfer material carrying member, which carries a transfer agent and rotationally moves to carry the transfer agent to a transfer portion on an image carrying member. The second surface of the transfer material carrier is placed with the transfer material carried on the first surface of the transfer material carrier interposed therebetween.
The second surface of the transfer material carrier while pressing the image carrier from the surface of
And a contact charging means for charging the surface of the transfer device.