JPS58106580A - Separating and carrying device of transfer material - Google Patents

Abstract

PURPOSE:To make a separate carrying device unnecessary, and to elevate reliability of separation by a simple constitution, by providing a separating belt so that its surface can contact with the surface of a photosensitive body, between 2 rollers for supporting te separating belt. CONSTITUTION:Among 4 rollers for supporting a conductive separating belt 20, a driving roller 21a and a belt tension roller 21b are opposed to a photosensitive drum 1. When the tip of transfer paper reaches a contact part of the belt 20 and the photosensitive body 1, the tip part is attracted by the belt 20 to which bias voltage of opposite polarity to a transfer charger 8 has been applied. The belt 20 is made to press-contact with the photosensitive body 1 by some area between the roller 21a and 21b, therefore, the tip part of the transfer paper is attracted to the belt 20 exactly. According to said constitution , a separate carrying means for carrying the transfer paper to the next process becomes unnecessary, and since the belt 20 contacts softly with the photosensitive body, the surface of the photosensitive body is not damaged, and separation can be executed exactly.

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 transfer paper by applying voltage to a transfer charger, and then this transfer paper is transferred to the photoreceptor. The images are separated, transported to a fixing section, fixed, and discharged outside the machine.

Conventional methods for separating the transfer paper on which the toner image has been transferred from the photoconductor include a separation claw whose tip is in contact with the circumferential surface of the photoconductor, or a separation claw provided near the transfer separation section on the transfer reference side edge KG of the transfer paper. Mechanical means such as an endless separation belt with a narrow width, a separation device using a pick-off belt, separator roller, or turn roller fixed at the same location as above, or negative pressure of air are used for transfer. Methods have been adopted to separate the paper by suction, or to install a separation charger immediately after the transfer charger and apply AC pressure to separate the paper, but these methods may damage the surface of the photoreceptor or damage the mechanism. There are disadvantages such as complexity and increased costs, white spots on the side edges of copies, and unstable separation performance that requires delicate adjustments. There is a drawback that separate transportation means are required for transportation to the process.

In particular, in the case of two-color electrophotographic copying machines such as red and black, development is performed using a developer with both positive and negative polarities, so separation using a separation charger is unsuitable because it tends to cause disturbances in the toner image transferred onto the transfer paper. be.

A conductive bell I/separation method is available as a method that improves these problems and enables full-surface transfer, does not damage images or photoreceptors, and can perform both separation and conveyance. The outline will be explained with reference to Fig. 1, which shows an example of the general layout when this method is applied to a two-color electrophotographic copying machine.
A primary charging charger 2.
Secondary charging charger 3, image exposure position 4, first developer (red) 5, second developer (black) 6, pre-charger 7,
A transfer charger 8, a conductive separation belt 9, a static elimination charger lO, a cleaning device 11, and a quenching lamp 12 are provided.

The conductive belt 9 shown in ``2'' is made of an endless metal thin 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, an image of a document consisting of, for example, red and black is exposed to light to form a positive and negative latent image on the photoreceptor, and then negatively charged by the first developing device 5. The entire red image is developed with the red developer, and then the black image is developed with the positively charged black developer in the second developer 6. Next, the two-color developed image formed on the drum L is aligned with the positive polarity by the precharger 7, and is transferred to the transfer charger 8 from the back side of the transfer paper 17 being conveyed at the appropriate timing.
.

When it comes to the contact point between the electrical separation belt 9 and the photoreceptor drum 1,
By applying a bias voltage of opposite polarity to the transfer charge to the conductive separation belt 9, the leading edge of the transfer paper 17 is attracted to the separation belt 9 and separated by the photosensitive drum. After the leading edge of the transfer paper 17 is attracted to the separation belt 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.

Now, when a full bias voltage of opposite polarity to the transfer charge is applied to the conductive separation belt 9, the transfer paper 17 is attracted to the belt 9, while a part of the toner transferred onto the transfer paper is transferred to the photoreceptor 1 again. It returns to the surface, lowers the transfer rate, and causes defective transfer areas.

Therefore, the voltage of the reverse polarity bias applied to the conductive separation belt and its application time are kept to a level necessary for the leading edge of the transfer paper to separate from the photoreceptor 1 and be attracted to the conductor belt.

As a result, a separation error sometimes occurs, and the transfer paper may wind around the photoreceptor drum.

SUMMARY OF THE INVENTION An object of the present invention is to provide a separation and conveyance device that eliminates the above-mentioned drawbacks of the conventional transfer paper separation and conveyance device using a conductive separation belt and has high separation reliability.

Hereinafter, the present invention will be explained in detail with reference to drawings showing embodiments thereof.

In the embodiment of the transfer paper separation and conveyance device using the conductive separation belt according to the present invention shown in FIG. 2, the conductive endless belt 2o has four rollers 21a.

21b, 21e, and 21d and driven in the direction of the arrow. Rollers 21a, 21c,
21d is pivotally supported by a unit board made of an insulating material fixed to the frame of the main body of the copying machine, and is electrically insulated from the frame of the main body. The roller 21a is a drive roller, and is driven to rotate in synchronization with the photosensitive drum l via a gear (not shown) provided at the end of its shaft, thereby causing the conductive bell 20 to rotate in the direction shown by the arrow in the figure. do. The roller 21b is used for belt tension, and one end is supported by the unit board and supported by a spring 22.The belt tension lever 28y is pivoted to rotate counterclockwise in the figure. )20 is pushed outward. This allows the belt 20 to maintain a constant and appropriate tension at all times. The rollers 21e and 21d are rollers for applying the full voltage to the belt 20, and the shaft ends of these rollers are connected to the applied voltage control circuit 15 via voltage applying electrodes.

At the position of the roller 21&, there is a gap of 0 to l+n+n between the outer surface of the belt 20 and the photoreceptor drum 1. The belt 20 is installed between the rollers 21a and 21b by installing the belt 21b so that a part of its circumference protrudes slightly toward the photoreceptor drum.
is in surface contact with the circumferential surface of the photosensitive drum 1 over a certain area. Further, the rollers 21c and 21d are positioned so that the bell 20' can be guided between these rollers in a direction in which the transfer paper is fed toward the fixing position.

Since this separating and conveying device is configured as described above, the leading edge of the transfer paper I7, which has been completely transferred and is sent while being in close contact with the photosensitive drum, is connected to the conductive belt 20 of this device and the photosensitive drum 1. When the tip reaches the contact point, the tip is attracted by the conductive belt 20 to which a bias voltage of opposite polarity to the transfer charge is applied. The voltage and application time of the reverse polarity bias applied to the belt 20 are kept to the necessary minimum in relation to the transfer rate as described above, but in this device, the belt 20 has a certain area between the rollers 21a and 21b. Since the transfer paper 17 is rotated at the same speed as the circumferential speed of the photoreceptor drum while being pressed against the photoreceptor drum 1, the leading edge of the transfer paper 17 is reliably attracted to the surface of the belt 20, and the belt 20 moves the transfer paper 17 to the rollers 21c and 21d. transported in the direction of Moreover, since the roller 21b always applies an appropriate tension to the belt 20 by the spring 22, the belt 20 can be brought into soft surface contact with the photoreceptor drum l. Even if the photoreceptor drum l is made of a thin metal plate, even if an excessive force is applied to the photoreceptor drum l or hard dust etc. gets into the gap between the photoreceptor drum l and the belt 20, the photoreceptor drum There will be no dents or scratches on the l and belt 20. The belt 20 is turned in the direction toward the fixing device by rollers 21c and 21d, whereby the transfer paper 17 separated from the photoreceptor drum 1 and adsorbed to the belt 20 is conveyed in the direction toward the fixing device. The transfer paper is placed on the belt 20 at the part where the belt 20 makes a U turn by the roller 21d.
Appropriate means 24 such as separation claws are provided, and the transfer paper is separated and conveyed along the fixing kite plate 25 to the fixing device.

As before, a cleaning blade 26 is provided so that its tip touches the surface of the belt 20 downstream of the transfer paper peeling position, and a toner discharge coil 27 is provided to discharge the toner scraped off by the cleaning blade 26. It is.

In the above embodiments, a roller is most commonly used as the conductive belt support member, but depending on the position of use, a sliding guide may be used.
It is also possible to use an appropriate one such as. In addition, if there are at least three supporting members, two of them are brought into surface contact with the belt tracker photosensitive drum, and the other one is placed in the belt position.
-' can be turned in the desired direction.

Furthermore, as mentioned above, the present invention is particularly effective for two-color electrophotographic copying machines in which the use of a separation charger as a separation device is not suitable, and therefore, in the description of the conventional device, a two-color electrophotographic copying machine is used as an example. However, it goes without saying that the present invention can be applied not only to a transfer paper separation and conveyance device of a two-color electrophotographic copying machine, but also to a transfer paper separation and conveyance device of an ordinary monochrome copying machine, and similar effects can be obtained.

As described above, according to the present invention, it is possible to obtain a remarkable effect in improving the reliability of a transfer paper separation and conveyance device using a conductive separation belt, which is simple in structure, can perform full-surface copying, and does not require a separate conveyance device.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a conventional transfer paper separating and conveying device using a conductive belt, and FIG. 2 is a sectional view showing an embodiment of the present invention. l...Photosensitive drum 8...Transfer charger 1
7...Transfer material 20...Conductive endless belt 21a,...21d...Roller (support part),...
0 11-

Claims (2)

[Claims] (1) A separation belt consisting of an endless conductive belt that is supported by a plurality of belt support members and rotates in contact with the photoreceptor after the toner image formed on the photoreceptor is transferred to a transfer material using a transfer charge. Apply a bias voltage to
In a transfer material separation and conveyance device of an electrophotographic copying machine that adsorbs the transferred transfer material and conveys the transferred material separately from the photoreceptor, the separation belt described above is rotatably movable by three or more belt support members. Two of the supporting members are disposed such that the separating belt is in surface contact with the surface of the photoreceptor between them, and the other supporting member is arranged in the direction in which the separated transfer belt is to be transported. A separation conveyance device characterized in that it is arranged to guide a separation belt tracker. (2) Claim 1, characterized in that the copying machine provided with the transfer material separation and conveyance device is a two-color electrophotographic copying machine.
Separation and conveyance device as described in section.