JPS6254737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field of the Invention The present invention relates to an automatic paper loading device applied to printing devices such as electrophotographic devices, and particularly to an automatic paper loading device that can smoothly convey paper. It is related to.

(B) Background of the technology Several proposals have been made for methods of engaging paper transport holes with transport protrusions on a tractor when automatically loading paper into a paper transport device, and improvements are still being made. is being actively carried out.

(C) Prior Art and Problems FIG. 1 is a diagram for explaining a paper conveying device in an electrophotographic apparatus previously proposed by the applicant.

First, a latent image is formed on the photosensitive drum 1 by the latent image forming means 2. Next, the developing means 3 supplies developer powder to visualize the latent image formed on the photosensitive drum 1. Next, the visible image on the photosensitive drum 1 is transferred onto the paper 5 by the transfer means 4. After the transfer, developer powder remaining on the photosensitive drum 1 is removed by a cleaning brush 6.

On the other hand, the sheets 5 are sequentially pulled out from the hopper 16, pass over the sheet presser 18, and are conveyed to the tractor 7 and the transfer means 4. At this time, the transport speed of the paper 5 is preset to the same speed as the surface speed of the photosensitive drum 1. Then, the visible image formed on the photosensitive drum 1 is transferred onto the paper 5 by the transfer means 4. Next, it is sent to a tractor 8 and a heat fixing device 9, where it is heated and fixed, and then sent to a stacker 17 where it is folded.

Automatic paper loading will be described below.

The operator places and fixes the paper 5 with the paper presser stand 18 horizontal. Next, the paper presser 18 is rotated to engage the transport hole of the paper 5 with the transport protrusion of the tractor 7, and then the fixed paper 5 is released.

Next, the paper 5 is moved to the movable paper guide 1 by driving the front and rear tractors 7, 8 and the pinch roller 14.
2. The photosensitive drum 1 and the guide 10 are pushed into the curved conveyance path due to their rigidity. When the leading edge of the paper 5 reaches the pinch roller 14, the feeding force eliminates the slack in the paper.
It is inserted between the rear tractor 8 and the paper holding plate 15 in a taut state.

When the paper 5 reaches the pinch roller 14, the driving of the tractors 7 and 8 is stopped. Then, the slack in the paper 5 is removed by the conveyance force of the paper feed roller 14. After a predetermined period of time has elapsed, the tractors 7 and 8 are driven again to start transporting the paper 5. At this time, the pinch roller 14 is driven at a speed faster than the paper conveyance speed of the tractors 7 and 8.

Although this device can automatically load paper smoothly, it is necessary to apply sufficient tension to the paper 5 by the paper presser plate 15 after the protrusion of the rear tractor 8 engages the paper feed hole of the paper 5. However, since the pinch roller 14 was driven even though it was possible to do so, the paper feed hole of the paper 5 could be damaged, which had a disadvantage in that it had an adverse effect on subsequent printing and the like.

(D) Object of the Invention In view of the above-mentioned conventional drawbacks, an object of the present invention is to provide an automatic paper loading device that can always carry out smooth paper feeding.

(E) Structure of the Invention The object of the present invention is to have a conveyance protrusion that engages with the paper feed hole of the printing paper and conveys the printing paper, and to sandwich the printing part and move the printing paper forward and backward in the conveyance direction. a pinch roller which is provided between the printing section and the rear tractor and is driven at a speed faster than the paper conveyance speed of the tractor to feed the printing paper; and an identification means for identifying the
When setting the printing paper, the pinch roller is placed in contact with the printing paper, and in response to the output of the identification means, the pinch roller is set after a predetermined time after the printing paper passes the pinch roller. This is accomplished by providing an automatic paper loading device characterized by displacing a roller to a separation position relative to the printing paper.

That is, the present invention identifies that the printing paper has been conveyed to the rear tractor position, and moves the pinch roller to the separation position in accordance with this result.

Therefore, after the printing paper 5 is engaged with the rear tractor 8, the driving force by the pinch roller 14 does not act on the printing paper 5.

Therefore, the paper feed hole of the printing paper 5 is not damaged during automatic paper loading, and the paper can be fed smoothly.

(F) Embodiment of the Invention An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a diagram for explaining one embodiment of the paper conveying device according to the present invention.

In the figure, by first pressing down a paper loading switch (not shown), the microcomputer 23 rotates the tractor motor 22 through the motor drive circuit 24 to drive the tractors 7 and 8, and also drives the pinch roller by the drive circuit (not shown). 14.

A rotary detector 25 is attached to the tractor motor 22 and outputs pulses corresponding to the conveyance length of the paper 5. Therefore, when the paper loading switch is pressed and the paper 5 is transported, the rotary detector 25 detects the amount of transport of the paper 5 and outputs a pulse signal. Rotary detector 25
The pulse signal output from the amplifier 26 is amplified by the amplifier 26 and input to the counter 27 .

The counter 27 counts the number of pulses preset by the microcomputer 23,
In other words, the number of pulses corresponds to the distance from the leading edge of the paper 5 loaded on the tractor 7 to the pinch roller 14, for example, the number of pulses corresponds to one pulse per paper transport length of 0.1 [mm], and the rotation When the pulse signal values from the formula detector 27 become equal, a coincidence signal is input to the microcomputer 23.

When the microcomputer 23 receives the match signal from the counter 27, it outputs a stop signal to the motor drive circuit 24.

The motor drive circuit 24 stops the tractor motor 22, that is, stops driving the tractors 7 and 8, and stops transporting the paper 5.

At the same time, the microcomputer 23 starts counting the reference clock from the reference clock oscillator 28.

At this time, the leading edge of the paper 5 is
The slack of the paper 5 is removed by the conveyance force of the paper feed roller 14.

After a predetermined period of time, the microcomputer 23
In other words, after the microcomputer 23 counts the reference clock a predetermined number of times, the motor drive circuit 24
Outputs the drive signal to. At the same time, counter 2
9 starts counting the reference clock.

The motor drive circuit 24 drives the tractor motor 22, drives the tractors 7 and 8, and starts transporting the paper 5.

Then, the counter 29 outputs a drive signal to the drive circuit 30 of the pinch roller moving motor 31 after a predetermined time has elapsed since the start of conveyance of the paper 5, that is, a time equivalent to the time that the paper 5 is conveyed to the rear tractor 8.
move the pinch roller 14 to the separation position 14';
Then, the drive motor of the pinch roller 14 (not shown) is stopped.

In other words, this counter 29 constitutes an identification means for identifying that the paper 5 has been conveyed to the rear tractor 8, and the output of this counter 29 moves the pinch roller 14 to the separation position 14', so that the paper 5 is transported to the rear tractor 8. No driving force is applied to the paper 5 after it is engaged with the tractor 8, and the paper feed hole of the paper 5 is not damaged. In this way, the paper presser plate 1
5 and tractors 7 and 8, and the pinch roller 14 is configured to avoid applying excessive tension to the paper 5. Note that the pinch roller moving motor 31 is driven only after a predetermined period of time has elapsed from the start of conveyance of the paper 5 on the tractors 7 and 8.
This is to apply sufficient tension to the paper 5 by the paper presser plate 15.

Furthermore, in this embodiment, as an identification means,
Although the case where the counter 29 is used has been explained,
The present invention is not limited to this, and any means that can identify that the paper 5 has been conveyed to the position of the rear tractor 8 can be used as appropriate.

(G) Effects of the Invention As described above in detail, according to the present invention, an identification means is provided for identifying that the printing paper has been conveyed to the position of the rear tractor, and this identification means is activated according to the output. Since the pinch roller for applying tension to the paper is separated from the paper, there is no need to apply extra tension after the paper is engaged with the rear tractor, and the paper can be conveyed smoothly. be.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an electrophotographic apparatus using a conventional paper conveyance device, and FIG. 2 is a diagram for explaining the paper conveyance device of the present invention. In the figure, 7 and 8 are tractors, 14 and 14'
1 is a pinch roller, 15 is a paper press plate, 22 is a tractor drive motor, 23 is a microcomputer,
24 and 30 are motor drive circuits, 25 is a rotary detector, 26 is an amplifier, 27 and 29 are counters, 28
3 is a reference clock oscillator, and 31 is a pinch roller moving motor.

Claims (1)

[Scope of Claims] 1. A tractor having a conveyance protrusion that engages with a paper feed hole of the printing paper to convey the printing paper, and is provided at the front and rear of the printing paper in the conveyance direction, sandwiching the printing section; a pinch roller that is provided between the printing section and the rear tractor and is driven at a speed faster than the paper conveyance speed of the tractor to feed the printing paper; and an identification means for identifying that the printing paper has been conveyed to the position of the rear tractor. and arranging the pinch roller in contact with the printing paper when setting the printing paper, and responding to the output of the identification means for a predetermined period of time after the printing paper passes the pinch roller. An automatic paper loading device characterized in that the pinch roller is later displaced to a separation position with respect to the printing paper.