JPS6091375A - Separating device for transfer paper - Google Patents

Abstract

PURPOSE:To separate transfer paper from a photosensitive body effectively without using any assisting material for separation by bringing the transfer paper into contact with the photosensitive body which has curvature less than a 10 radius R at least partially. CONSTITUTION:The photosensitive body 1 contacting the front end part of the transfer paper 2 runs off at right angles to the straight advance direction of the paper 2 because of the curvature of a photosensitivd body driven roller 1b. The diameter of the roller 1b is less than the 10mm. radius R. Further, when the photosensitive body 1 and paper move by nearly the same extents, the paper 2 reaches a fixation guide 12 and is separated from the photosensitive body 1 securely.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for separating a transfer paper from a photoreceptor in an electrophotographic copying apparatus.

Structures of conventional examples and their problems Conventional transfer paper separation devices include one based on electrical processing using a separation charger, one based on mechanical processing using a separation belt, and one based on electrical processing using the above-mentioned separation charger and separation claw. Some use mechanical processing in combination.

Generally, an electrophotographic copying apparatus forms an electrostatic latent image by charging a photoreceptor formed in the shape of a drum or belt with a charging charger and exposing it to light. Develop this with toner,
With the transfer paper in contact with the developing surface, a transfer charger applies corona discharge to the transfer paper with a polarity opposite to the charge held by the toner, thereby transferring the developed toner image on the photoreceptor to the transfer paper. Next, when the transfer paper on which the toner image has been transferred is separated from the surface of the photoreceptor, the transfer paper has an extra charge of opposite polarity to the toner due to the corona discharge for the transfer. , the transfer paper is attracted to the photoreceptor by this electrostatic attraction. This makes it difficult to separate the transfer paper from the photoreceptor. As one of the devices to easily separate this, a separation charger is provided separately from the transfer charger, and this removes the excess charge generated during transfer.
A so-called electrostatic separation device is used, which is electrically treated so that the transfer paper naturally separates from the photoreceptor due to its rigidity and weight. As described above, the electrostatic separation device must include a separation charger in addition to the transfer charger. Furthermore, since the separation charger uses alternating current (AC) corona discharge, it is necessary to provide an AC high voltage power source. On the other hand, a separation belt device that processes separation mechanically has a transfer guide 6 as shown in FIGS. 1 and 2.
The transfer paper 2 guided by the photoreceptor drum 1 is
The toner image formed on the surface of the photosensitive drum 1 by the image forming means is transferred by the transfer charger 6.

At this time, one end A of the transfer paper 2 is held between the separation belt 3 and the separation roller 4, and the end of the transfer paper 2 away from the image area is moved along the end of the transfer material conveyance path of the photoreceptor drum 1. It advances without contacting the photoreceptor drum 1.

On the other hand, the portion of the image area near the center other than the above-mentioned end portion is in contact with the photoreceptor drum 1, and the toner image is transferred by the transfer charger 5, progressing at the same speed as the photoreceptor drum 1, and the transfer and separation are completed. It is done. As is clear from the above, the end portion of the transfer paper held by the separation belt exists separately from the image area. Therefore, the image is deleted from the edges of the copied image (the part held by the separation belt), and there is a drawback that the entire image cannot be copied.

There is also another separation device that uses a separation charger and separation claws together. As shown in FIG. 3, this device uses a transfer guide 6 to transfer a toner image formed on the surface of the photoreceptor drum 1 by an image forming means to a transfer paper 2 guided to a photoreceptor drum 1 by a transfer charger 5. and then separated by a separation charger 7. However, the force that separates the transfer paper 2 from the photoreceptor drum 1 easily changes depending on the surrounding environmental conditions such as humidity.
There are times when the separation of the transfer paper 2 from the photoreceptor drum 1 is insufficient, or when the transfer paper 2 is not separated at all. At these times, the transfer paper 2 is separated from the photoreceptor tram 1 by the separating claw 8 in the direction of the arrow as shown by the dashed line. but,
In this case, there is a drawback that the unfixed toner image held on the surface of the transfer paper 2 is rubbed when it comes into contact with the separation claw 8, and a mark is formed on the toner image. Furthermore, there is a problem that the separation claw constantly contacts the photoreceptor, causing scratches on the surface of the photoreceptor.

In order to solve the above-mentioned problems, a transfer paper separation device as shown in FIG. 4 has been proposed, which separates the transfer paper from the photoreceptor without using a separation charger, a separation belt, or a separation claw. As shown in FIG. 4, the transfer paper 2 guided by the transfer guide 6 to the belt-like photoreceptor 1 in contact with the photoreceptor driving drum 1a transfers the toner image formed on the surface of the belt-like photoreceptor 1 by the image forming means. The image is transferred by the transfer charger 5. The leading edge of the transferred transfer paper advances to the photoconductor driven roller 1b. At this time, the leading edge of the transfer paper 2 tries to move straight due to the rigidity of the paper, but the belt-shaped photoreceptor 1 that is in contact with the leading edge of the transfer paper 2 changes due to the curvature of the photoreceptor driven roller 1b, and as a result, the transfer paper 2 The tip of the photoreceptor 1 and the belt-shaped photoreceptor 1 in contact with it separate from each other in a very short time. When the transfer paper 2 further advances, the photoreceptor 1 is
The electrostatic attraction force due to the rigidity of the transfer paper 2 is weakened, so that the electrostatic attraction force becomes relatively strong, and the transfer paper 2 is attracted to the belt-shaped photoreceptor 1 again. A device that skillfully utilizes the phenomenon described above is an electrostatic adsorption separation device. A separation aid 9 is placed at a position where the transfer paper 2 is separated from the body 1, the leading edge of the transfer paper 2 is brought into contact with the separation aid 9, and the electrostatic adsorption force due to the charge of the transfer paper 2 itself after transfer is used to There is also a device that allows separation by adsorption to the separation auxiliary material 9. However, with this device, dirt adheres to the surface of the separation aid 9 due to toner scattering within the copying machine. This toner stain causes toner stains on the back side of the transfer paper when the transfer paper is separated, so there is a problem in that duplex copying is only possible using the front and back sides of the transfer paper. moreover,
To solve this problem, we rotated the separation aid, and
This requires cleaning means such as bringing a cleaning brush into contact with the separation auxiliary material, resulting in a problem that the copying machine has a complicated structure.

OBJECTS OF THE INVENTION An object of the present invention is to provide a transfer paper separation device that effectively separates transfer paper from a photoconductor without using a separation charger, a separation belt, a separation claw, or a separation aid. .

Structure of the Invention The present invention uses a photoreceptor in which at least a portion has a radius of curvature of R10 or less, so that the transfer paper is naturally separated from the photoreceptor by utilizing straightness due to the rigidity of the transfer paper after transfer. This structure allows for stable separation of the transfer paper, simplifies the structure of the copying machine, and enables full and double-sided copying of images.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 5 shows a schematic diagram of a copying machine to which the transfer paper separating device of the present invention is applied. In FIG. 5, 1 is an endless belt-shaped photoconductor (hereinafter referred to as a photoconductor) using an organic photoconductor, 1a is a photoconductor driving drum with a diameter of 100 mm, and 1b is 1
5 mmφ photoconductor driven roller, 2 is a transfer paper, 6 is a transfer guide, 1Q is a charging and transfer charger, 11 is a fixing guide, 12 is a cassette containing the transfer paper 2, 1
3 is a feed roller, 14 is a pair of transport rollers, 15 is a developing device, 16 is an exposure device including an optical fiber lens 16a and a lamp 16b, 17 is a cleaning device, 18 is a photoreceptor static elimination lamp, 19 is a fixing device, and 20 is an ejector. It's a paper tray.

The operation of the transfer paper separation device of this embodiment configured as described above will be described below.

The transfer paper 2 indicated by a broken line in FIG. 6 is sent to the transfer guide 6 by a pair of transport rollers 14.

Next, the transfer paper 2 is guided to the photoreceptor 1 and is brought into close contact with the photoreceptor 1 electrostatically, and the toner image formed on the photoreceptor 1 is transferred by a charging and transfer charger 10 .

The leading edge of the transfer paper 2, indicated by the broken line, tries to move straight due to the rigidity of the paper.

On the other hand, due to the curvature of the photoreceptor driven roller 1b, the photoreceptor 1 that is in contact with the leading end of the transfer paper 2 changes so that the photoreceptor 1 escapes from the straight movement of the transfer paper 2. Furthermore, photoreceptor 1
When the transfer paper 2 advances at the same rate, the transfer paper 2 reaches the fixing guide 12, and the transfer paper 2 is reliably separated from the photoreceptor 1.

Furthermore, in order to achieve the most suitable conditions for the present invention, the diameter of the photoreceptor driven roller was set to 10mmφ, 20mmφ, 30mmφ,
When testing was carried out for each diameter of 40 mm, it was confirmed that the upper limit of the diameter of the photoreceptor driven roller, which is a practical problem in the present invention, is 20 mm. This is because when the diameter is made larger than 20 mm, the force due to the rigidity of the transfer paper becomes inferior to the adhesion force between the photoreceptor and the transfer paper. In other words, the leading edge of the transfer paper follows the change in the curvature of the photoreceptor roller due to the adsorption force, which reduces the separation performance between the photoreceptor and the transfer paper, and further deteriorates the separation performance depending on the surrounding environment. be. On the other hand, the diameter of the photoconductor driven roller is 20rrr.
When the diameter is smaller than mφ, the change in the curvature of the photoconductor becomes large, and the force due to the rigidity of the transfer paper is relatively stronger than the adsorption force between the transfer paper and the photoconductor, which strengthens the straightness of the transfer paper and improves the separation performance. .

In the embodiments of the present invention, a feature of the present invention is that a photoconductor driven roller is used in a portion that greatly affects the separation performance to make a portion of the photoconductor have a radius of curvature of R10 or less. However, the roller is not limited to a driven roller, and any roller can be used as long as it can make a part of the photoreceptor have a curvature of 10R or less.

For example, a fixed backing plate can be used by providing a plate whose surface has been processed to have a curvature of radius R1o or less in place of the driven roller of the photoreceptor.

Effects of the Invention As is clear from the above explanation, the present invention uses a photoreceptor, at least a portion of which has a radius of curvature of less than R1o, to separate the transfer paper from the photoreceptor, thereby separating the transfer paper after transfer. The structure allows the transfer paper to naturally separate from the photoconductor due to the straightness due to the rigidity of the transfer paper and the change in the curvature of the photoconductor in contact with the leading edge of the transfer paper, so there is no need for a conventional separation charger or AC power supply. In addition, since there is no need for a separation belt or separation claws, images can be copied over the entire surface, and there is no problem with separation claw marks, and there is no need to use separation aids, so toner stains on the separation aids can be avoided. Since the dirt on the back side of the transfer paper was removed, double-sided copying became possible.

As mentioned above, the configuration of the copying machine has become extremely simple because what was required in the past has been made unnecessary, which is a great effect.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a conventional transfer paper separation device, FIG. 2 is a side view thereof, FIGS. 3 and 4 are side views showing other examples of the conventional transfer paper separation device, and FIG. 5 is a side view of a conventional transfer paper separation device. FIG. 6 is a schematic diagram of a copying machine to which an embodiment of the invention is applied, and FIG. 6 is a side view of essential parts of a transfer paper separation device of the invention. 1... Belt-shaped photoconductor, 1b... Photoconductor driven loaf - 0 Name of agent Patent attorney Satoshi Nakao and 1 other person 1st
Figure 2 Figure 3 rfIJ Figure 4 Figure 5 jθb Figure 6

Claims (1)

[Claims] A transfer paper separation device characterized in that a photoconductor is used, at least a portion of which has a radius of curvature R10 or less, and the transfer paper is brought into contact with the photoconductor.