JPS6313900B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention involves forming a latent image by exposing a photoreceptor to light,
The present invention relates to a paper feeding mechanism for an electrophotographic printing machine that develops this latent image, transfers it to paper, and then fixes it to print.

Conventionally, as shown in FIG. 1, a paper feeding mechanism in an electrophotographic printing machine of the above type has two pairs of tractors 2, 2 for transporting paper 1, and a photosensitive drum 3.
The paper 1 passes between the transfer device 4 and the photosensitive drum 3, which are provided between the tractors 2 and 2 on the same side as the drum 3, while being in sliding contact with the drum 3. Then, the latent image on the drum 3 is transferred. In the above-mentioned conventional paper feeding mechanism, the two pairs of tractors 2, 2, which are synchronously driven by timing belts, etc., are installed at different positions.
In addition, due to stretching of the timing belt, etc., the protruding pawl of the tractor 2 does not properly engage with the feed hole of the paper 1, and as a result, the latent image on the photosensitive drum 3 is not aligned with the paper 1.
This has the disadvantage that the paper 1b is transferred out of alignment, and furthermore, it is difficult to fold the paper 1b after printing. Moreover, in the above conventional mechanism, the tractors 2 and 2 are disposed on the same side as described above, and due to constraints such as the size and structure of the printing machine, the distance between the paper 1a before printing and the paper 1b after printing is A disadvantage in use also arises in that the paper 1 cannot be provided widely and therefore it is difficult for the operator to load the paper 1 onto the tractor 2, 2.

The present invention aims to solve the above-mentioned conventional drawbacks, improve the reliability of printing functions, and propose an electrophotographic printing machine that can easily load paper.

In order to achieve the above object, the present invention is directed to an electrophotographic printing machine in which a photoreceptor is exposed to light to form a latent image, this latent image is developed and transferred to paper, and then fixed and printed. , a tractor provided upstream of the paper with respect to the photoconductor and feeding the unprinted paper to the photoconductor at a speed approximately equal to the circumferential speed of the photoconductor; and a tractor provided downstream of the paper with respect to the photoconductor; The content of the electrophotographic printing machine is an electrophotographic printing machine having a friction roller provided on the side thereof and rotating at a speed higher than the circumferential speed of the photoreceptor to eject the transferred paper from the photoreceptor.

The present invention will be described below based on an embodiment shown in the drawings.

FIG. 2 shows a schematic diagram of the paper feeding mechanism according to the present invention, in which the front and rear (second
Paper sheets 1a and 1b before and after printing are arranged in the left-right direction in the figure), and from the point of sliding contact between the paper 1 and the photosensitive drum 3, there is a pair of tractors 2 on the front side of printing, and a set of friction wheels on the side after printing. A roller device 5 is provided to convey the paper 1. The tractor 2 may be of the same type as the conventional one, for example, one having a function of sending out the paper 1 by providing a protruding pawl on the conveyor belt, and driven in accordance with the circumferential speed of the drum 3. It is something.

The friction roller device 5 sends out the paper 1 using frictional force, and as shown in FIG. a case 7 which is provided so as to cover the roller 6 and has an opening 7a only at the place where the roller 6 and the paper 1 make sliding contact; a vacuum pump 8 which reduces the pressure inside the case 7; It consists of a guide cover 9 that guides the. Friction roller device 5 configured by the above-described suction method
, the paper 1 in the opening 7a of the case 7
is always maintained by the roller 6 due to the suction force into the case 7.
The rollers 6 are in sliding contact with each other, and are stably conveyed by the rotation of the rollers 6. The roller 6 is
It rotates at a circumferential speed that is slightly faster than the circumferential speed of the photosensitive drum 3.

FIG. 4 shows an example of the roller 6. In the figure, the roller 6 is formed in a stepped front shape, and the pitch l across the opening 9a of the guide cover 9 is reduced to 1/1. It is set at 2 inches.
The rollers 6 and guide covers 9 are formed at such intervals in most cases where the width of the paper 1 used in this type of electrophotographic printing machine is a multiple of 1/2 inch. This is to prevent the left and right ends of the paper 1 from getting caught up in the rollers 6. Note that the circumferential surface of the roller 6 is preferably coated with, for example, urethane rubber in order to increase the frictional force with the paper 1.

FIG. 5 is a longitudinal sectional front view showing another embodiment of the roller 6, in which the roller 6 is provided with dovetail-shaped through holes 6a at predetermined intervals.
This makes it possible to increase the suction force of the paper 1 to the roller 6. Note that the shape and structure of the roller 6 are of course not limited to the above-described embodiments.

The operation of the electrophotographic printing machine using the paper feeding mechanism configured as described above will be explained as follows.

In FIG. 2, in the printing press of the present invention, a photosensitive drum 3 rotating in the direction of the arrow is uniformly charged by a charger 11, and the drum 3 is irradiated with light 12 to form a latent image. The image is visualized by the developing device 13 and transferred onto the paper 1 by the transfer device 4. The transferred image on the paper 1 is fixed by the fixing device 14 and becomes a printed image. After the transfer, the photosensitive drum 3 is cleaned by a static eliminating fluorescent lamp 15, a cleaning brush 16, etc., and the above-described latent image formation, development, and transfer are repeated again. At this time, the paper 1 is being transported by the tractor 2 and the friction roller device 5,
Since the roller 6 rotates rather quickly, the paper 1 is stuck between the roller 6 and the tractor 2 to prevent it from loosening. Also, when loading paper, when paper 1 is installed on tractor 2,
The paper 1 is passed through the guide 10 and the transfer device 4 by the tractor 2, reaches the roller 6, and is forcibly conveyed by the friction roller device 5, whereby the paper 1 is The present invention can be easily attached to a printing machine.
According to the inventor's experiments, when paper 1 is initially installed, thin paper such as 45Kg or 55Kg paper is folded in half at the horizontal perforations and then transported to tractor 2.
It has been found that more reliable paper loading can be achieved if the paper is attached to the paper.

As explained above, in the present invention, since the paper feeding mechanism is configured using a friction roller device consisting of a pair of tractors and a set of suction type, there is no possibility of misalignment occurring in the sliding contact between the paper and the photosensitive drum. Furthermore, even if a flash lamp or the like is used in addition to the fixing roller as the fixing device, it is possible to apply appropriate tension to the paper in the transfer device.

Moreover, in the present invention, a tractor with a conveyance speed approximately equal to the circumferential speed of the photoconductor is provided upstream of the photoconductor, and a roller with a circumferential speed faster than the photoconductor is provided downstream, so that the surface of the photoconductor The relative speed with respect to the paper can be made zero, so the paper does not bend on the surface of the photoreceptor, and therefore high-quality printing is possible with a simple configuration.

Furthermore, to load paper into the printing machine of the present invention, it is only necessary to engage and attach the leading end of the paper to the tractor, and therefore, the present invention can eliminate the difficulty of conventional paper loading. It has the following effects.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a paper feeding mechanism of a conventional electrophotographic printing machine, FIG. 2 is a schematic diagram of a paper feeding mechanism according to the present invention, FIG. 3 is a partially sectional side view showing a friction roller device, and FIG. 4 3 is a partially omitted front view showing the roller of the suction and feeding device of FIG. 3, and FIG. 5 is a partially omitted sectional front view showing another embodiment of the roller of FIG. 4. 1... Paper, 2... Tractor, 3... Photosensitive drum, 4... Transfer device, 5... Friction roller device, 6... Roller, 7... Case, 8... Vacuum pump, 9... Guide cover, 10... Guide, 11... Charger, 12... Light irradiation, 13...
Developing device, 14... Fixing device, 15... Static elimination fluorescent lamp,
16...Cleaning brush, l...Pitch.

Claims (1)

[Claims] 1 A photoreceptor is exposed to light to form a latent image, this latent image is developed and transferred to paper by a transfer device facing the photoreceptor, and then a In an electrophotographic printing machine that performs printing by fixing with a fixed fixing device,
a tractor provided upstream of the paper with respect to the photoconductor and feeding the unprinted paper to the photoconductor at a speed substantially equal to the peripheral speed of the photoconductor; and a tractor downstream of the paper with respect to the photoconductor. and a friction roller that is provided between the transfer device and the fixing device and rotates at a speed faster than the circumferential speed of the photoreceptor to convey the transferred paper to the fixing device. Electrophotographic printing machine.