JPS58105267A - Separating and carrying device of transfer material - Google Patents

Abstract

PURPOSE:To make a separating pawl unnecessary, to simplify a device, and to prevent a belt from being damaged, by setting a radius of curvature of a separating belt in a position where transfer paper is separated, smaller than a radius of curvature by flexure of the transfer paper itself. CONSTITUTION:A conductive endless belt 20 is extended round four rolls 21a- 21d, and to the roll 21c, bias voltage is applied. A radius of curvature of the roll 21d of a transfer paper separating position is set small than a radius of curvature in case when transfer paper 17 is bent in a state that it has been attached to the belt 20. Therefore, when the transfer paper 17 comes to the separating position, it overcomes attracting force of the belt 20 by its own flexure and is peeled off, and the transfer paper 17 is carried to a fixing unit 19 stably. Therefore, it is unnecessary to provide a separating pawl, the device is simplified, and it is possible to prevent damage of the belt, which is apt to be caused by the separating pawl.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transfer material separation and conveyance device for an electrophotographic copying machine using a conductive endless belt.

In a transfer-type electrophotographic copying machine, a toner image formed on a photoreceptor through a predetermined process is transferred to a transfer paper under voltage application to a transfer charger, and then the transfer paper is is separated from the photoreceptor, transported to a fixing section, fixed, and discharged outside the machine. Conventionally, methods for separating the transfer paper on which the toner image has been transferred from the photoconductor include a separation claw that touches the circumferential surface of the photoconductor, or a transfer separation section along the conveyance reference side edge of the transfer paper. Mechanical means such as a narrow end lace separation belt installed nearby, a separation device using a pink-off belt fixedly installed at the same location as above, a separator roller, and a rind roller, or an air negative Methods that use pressure to suction and separate the transfer paper, and methods that install a separation charger immediately after the transfer charger and apply an AC voltage to separate the paper, have been adopted, but these methods do not apply pressure to the surface of the photoreceptor. There are disadvantages such as the mechanism is complicated, which increases costs, white spots appear on the side edges of copies, and separation performance is unstable because delicate adjustments are required. This method has the disadvantage that a separate conveying means is required to convey the transferred transfer paper to the next process.

- In the case of two-color electrophotographic copying machines, such as red and black beaks, development is performed using a developer with both positive and negative polarities, so separation using a separation charger tends to cause disturbances in the toner image transferred onto the transfer paper. (It is not suitable.

A conductive belt separation method is available as a method that can improve these problems and perform full-surface transfer without damaging an image or the photoreceptor (as well as separating and transporting images).

The outline will be explained with reference to FIG. 1, which shows an example of the schematic arrangement when this method is applied to a two-color electrophotographic copying machine. In order of direction: primary charging charger 2, secondary charging charger 7, image exposure position 4, 41st developer (
Red)5. Second developing device (black) 6, bleed charger 7, transfer charger 8, conductive separation belt 9, static elimination charger 10, cleaning device 11, quenching lamp 12
is installed.

The above-mentioned conductive belt 9 is endlessly made of a thin metal plate, such as nickel, and is wound around two rollers 13 and 14 and driven to rotate in the direction of the arrow. Conductive belt 9
An applied voltage control circuit 15 that can apply a bias voltage by switching between positive and negative or zero is connected to the holder, and a cleaning device 16 is in contact with the holder.

After being charged twice with different polarities by the primary and secondary charging chargers 2 and 3, a single image of, for example, red and black is exposed to form a positive and negative latent image on the photoreceptor. A red image is developed with a negatively charged red developer, and then a black image is developed with a positively charged black developer in the second developing device 6. Next, the two-color developed image formed on the drum 1 is aligned with the positive polarity by the bricharger 7, and is transferred from the back side of the transferred transfer paper 17 at the appropriate timing by the transfer charger 8. When the leading edge of the transfer paper 17 reaches the contact point between the conductive separation belt 9 and the photosensitive drum 1, the leading edge of the transfer paper 17 is separated by applying a /(Iasumi pressure of opposite polarity to the transfer charge to the conductive separation belt 9. bell)
9 and separated from the photoreceptor drum 1. After the leading end of the transfer paper 17 is attracted to the separation bell (9), the applied voltage control circuit 15 switches the bias voltage to the same polarity as the transfer charge or to zero to ensure transfer. The thus-adsorbed transfer paper is conveyed toward the fixing section by the conductive separation belt 9. The transfer paper 17 is peeled off from the conductive separation belt 9 near the fixing unit 19, guided by the fixing guide plate 18, and fed into the fixing unit 19.

Conventionally, separation claws have been used as a means of separating the transfer paper from the conductive endless belt, but when separation claws are used, the belt surface may be damaged by the claws, and the claws may become contaminated with toner. Jams are likely to occur due to dirt on the back of the transfer material and lifting of nails (also, if the belt is scratched, scratches will occur on the surface of the photoreceptor that comes into contact with it,
As a result, there are disadvantages in that uneven transfer occurs and the durability of the belt itself deteriorates.

SUMMARY OF THE INVENTION An object of the present invention is to provide a simple peeling means that eliminates the above-mentioned drawbacks of the separating claws that have been generally employed as a means for peeling a transfer material from a conductive endless belt.

The feature of this invention is that the radius of curvature of the conductive endless belt at the transfer material peeling position can be adjusted without using a dedicated member such as a separating claw as the peeling means.

Setting the dimensions and arrangement of the belt support member, such as a roller, so that the transfer paper used in the copying machine is smaller than the minimum radius of curvature that can be bent while being attracted to the belt by electrostatic force. Therefore, the transfer paper is not able to follow the bending of the belt at this portion and is peeled off from the belt due to its own bending stiffness.

The present invention will be described in detail below with reference to drawings showing embodiments thereof.

In the transfer paper separation and conveyance device according to the embodiment of the present invention shown in FIG.
It is wrapped around 1a, 21b, 21c, and 21d,
In synchronization with the 10 rotations of the photosensitive drum, it rotates in the direction indicated by the arrow in the figure at the same peripheral speed as that of the photosensitive drum. Roller 21m, 2
1c and 21d are pivotally supported on a unit board made of an insulating material which is firmly fixed to the copy unit, and the unit conveyed by one minute is electrically insulated from the machine frame. The roller 21b uses a spring (not shown) to push the belt 20 outward to apply a predetermined tension, and also to make surface contact between the roller 21m and the roller 221b over a certain area of the belt 20 on the circumferential surface of the photoreceptor drum 1. It is located in a suitable position. Rollers 21c, 21
d is the bell between them) 20 direction is the fixing unit 19
Its position is set so that it faces the intake port. The roller 21c is connected to an applied voltage control circuit via an electrode for applying a bias voltage.

The roller 21d also serves as a separation roller for wrapping the belt 2o around it and making a U-turn, as well as imparting a required radius of curvature to the belt 20 constituting the present invention. A fixing guide plate 22 is provided between the separating roller 21d and the paper receiving opening of the fixing unit 19.

The operation of this device will be explained below.

When the leading edge of the transfer paper 17 that has been transferred and sent by the transfer charger 8 while being in close contact with the photoreceptor drum 1 reaches the separation position where the conductive endless belt 2o and the photoreceptor drum 1 come into contact, a transfer charge is applied to the belt 20. A bias voltage opposite to that of the transfer paper is applied, and the leading edge of the transfer paper and the belt 20 come into surface contact, thereby ensuring that the belt 2DK is attracted, peeled off from the photoreceptor drum 1, and attached to the belt while being attached to the roller 2.
It sequentially changes direction at 1b and 21c and moves toward the roller 21d. The belt 20 makes a U-turn from the roller 21dK along the outer circumference of the roller 21d with a small radius of curvature, but the radius of curvature is such that the transfer paper overcomes the adhesion force to the belt 20 due to its own bending rigidity and peels off, as described above. Since the radius is determined to be suitable, the transfer paper 17 is separated from the belt 20 at this portion and is conveyed along the fixing guide plate 20 toward the fixing unit 19.

Now, a nickel belt with a thickness of 40 μm is used as the conductive endless belt 20 of the above-mentioned transfer paper separation and conveyance device, and paper with a basis weight of 40 to 6097 m'', which is commonly used as transfer paper, is used. Used at a temperature of 15°C to 20°C.
Separation roller 2 under environmental conditions of ℃ and humidity 30-70%.
When a peeling experiment was carried out on transfer paper with various diameters of 1d, when a roller with a diameter of 50 fins was used, the paper curved along the belt and remained adsorbed to the belt and was not separated. When the diameter of the separating roller 21d is 24 ma (the radius of curvature is 12 u), the transfer paper is separated.

It did not separate or became unstable. Separation roller 2
When the diameter of 1 m was 22 m, the transfer paper was stably separated and conveyed along the fixing guide plate 22. A good setting position of the fixing guide plate 22 at this time is shown in FIG.
The values of h ``'' 5 m18°d = 2 ms, respectively. -h is the distance between the transfer paper conveyance path and the tip of the fixing guide plate, and d is the distance between the outer peripheral surface of the separating roller 21d and the tip of the fixing guide plate.

If d is made larger or h is made smaller than this, even if the diameter of the roller is 22IIJ, the transfer paper will not reach the fixing guide plate.
2 and ends up getting between the end of the guide plate and the belt 20 wrapped around the roller.

Considering changes in paper quality and use environment, it is desirable that the diameter of the separation roller be 2011J or less.

Furthermore, there is naturally a limit to the flexibility of the belt, and it has been found that when a nickel belt with a thickness of 40 μm is used, it is possible to support a roller up to a diameter of 6N. Therefore, the diameter of the separation roller can be selected from 6 to 20 WJ, taking into consideration the arrangement and function of the transfer paper separation and conveyance belt unit and related devices.

As described above, according to the present invention, there is no need to provide a separate peeling member to peel the transfer paper from the separation and conveyance belt, and the device is simplified, which can easily occur when a one-separation claw is used. It is also possible to prevent scratches on the belt and stains on the back side of the transfer material caused by dirt from fingernails, resulting in significant improvements in belt durability, device reliability, and cost reduction.

Note that this separation and conveyance device is particularly useful for two-color electrophotographic copying machines in which it is difficult to use a separation charger.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram illustrating the configuration of a conventional transfer paper separating and conveying device using an electroconductive endless belt, and FIG. 2 is a sectional view showing an embodiment of the present invention. 1... Photoreceptor 8... Transfer charger 1
7... Transfer material 20... Separation belt 21m,
21b, 21c, 21d -- Belt support member 21d.
・Separation roller”

Claims (3)

[Claims] (1) After the toner image formed on the photoreceptor is transferred to a transfer material under a transfer charge, separation is made of an endless conductive belt that is supported by a plurality of belt support members and rotates in contact with the photoreceptor. A transfer material separation and conveyance device for an electrophotographic copying machine that applies a bias voltage to a belt, attracts the transferred transfer material to the belt, separates it from a photoreceptor, conveys it, and then peels the transfer material from the separation belt. , the radius of curvature of the separation belt at the position where the transfer material is separated from the separation belt is the minimum radius of curvature at which the transfer paper used in the copying machine can bend while being attracted to the separation belt. 1. A transfer material separating and conveying device characterized in that the shape, size, and arrangement of the support member are set so that the support member is smaller than the size of the support member. (2) Claim 1, characterized in that the copying machine provided with the transfer material separation and conveyance device is a two-color electrophotographic copying rack.
The transfer material separation and conveyance device described in 2. (3) When using paper with a basis weight of ``a o y /ln'' or more as the transfer material, the radius of curvature of the separation belt at the above-mentioned peeling position is set to be less than 12 mm. Or the transfer paper separation and conveyance device according to item 2.