JPH02106531A - Sheet supply method for image forming device - Google Patents

Abstract

PURPOSE:To stably convey charts by laying the front end part of a following chart over the rear end part of a preceding chart abutted on a resister roller, conveying the following chart in an extremely short time after conveyance of the preceding chart, thereby speeding up continuous conveyance of the charts. CONSTITUTION:When a preceding chart is abutted on a resister roller 33 to make a loop and then drive of a conveying roller 32 is stooped, an optical system exposing an original image is operated to expose the original image. An electrostatic image corresponding to the original image is thus formed on a sensitive drum 10, and the electrostatic image is developed by toner. In this way, while a toner image is formed on the drum 10, a following chart 60 is conveyed and its front end part overlaps the rear end part of the loop-shaped preceding chart. Thus, while the toner image is formed on the drum 10, roller 33, 32 are driven in synchronism with a specified timing of rotation of the drum 10, the loop-shaped preceding chart is conveyed to the drum 10 by the roller 33 through a third conveying roller 34.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to recording paper on which a predetermined image is transferred to an image carrier on which the image is formed, in an image forming apparatus such as an electrophotographic copying machine or a printer. Regarding how to feed paper.

(Prior Art) In an electrophotographic copying machine, after a predetermined toner image is formed on a photoreceptor drum that is an image carrier, a recording paper is conveyed to the photoreceptor drum, and the toner image is transferred onto the recording paper. be done. When feeding the recording paper to the photoreceptor drum, the image will not be transferred to a predetermined position on the recording paper unless the timing at which the image is formed on the rotating photoreceptor drum and the timing at which the recording paper is conveyed are synchronized. For this reason, conventionally, the timing at which an image is formed on a photoreceptor drum is after the recording paper is fed one by one from the recording paper storage section to the registration rollers, and the conveyance of the recording paper is stopped by the registration rollers. The registration rollers are driven in synchronization with the recording paper to convey the recording paper to the photoreceptor drum. After the recording paper passes through the registration rollers, the recording paper is newly conveyed from the recording paper storage section to the registration rollers.

Recently, there has been a demand for such electrophotographic copying machines to be able to perform continuous copying at high speeds, and efforts have been made to speed up the exposure scanning of originals as well as the continuous conveyance of recording paper. .

(Problems to be Solved by the Invention) However, in order to increase the speed of continuous conveyance of the recording paper, it is sufficient to increase the conveyance speed of the recording paper itself.

However, if the conveyance speed of the recording paper is increased, there is a problem that the conveyance of the recording paper will not be stable, leading to clogging, and the noise will be increased.

In order to increase the continuous conveyance of recording paper without increasing the conveyance speed of the recording paper, for example, Japanese Patent Laid-Open No. 60-8735
As disclosed in Publication No. 9, the trailing edge of the recording paper that has been fed to the registration rollers and stopped is overlapped with the leading edge of the recording paper that follows the recording paper, and the image recording paper is It is sufficient to continuously feed the photoreceptor drum. However, in the copying machine disclosed in the publication, two sheets of recording paper are continuously conveyed to the photoreceptor drum, so it is difficult to continuously copy the copied image of one document onto multiple sheets of recording paper. The problem is that it is not possible.

The present invention solves the above-mentioned conventional problems, and its purpose is to shorten the feeding time of recording paper even when the same image is continuously formed, and therefore to reduce the continuous conveyance of recording paper. An object of the present invention is to provide a paper feeding method for an image forming apparatus that can increase the speed.

(Means for Solving the Problems) The present invention temporarily stops recording paper fed through a conveyance path at a registration roller, and transfers the recording paper to an image carrier on which a predetermined image is formed by the registration rollers. A paper feeding method for an image forming apparatus in which a subsequent recording paper is fed so that the leading edge of the subsequent recording paper overlaps the trailing edge of the preceding recording paper that has been stopped by a registration roller. and a step of transporting the preceding recording paper after it passes a predetermined position until it comes into contact with the registration roller and stops when the preceding recording paper is fed to the image carrier by the registration rollers. ,
The above object is thereby achieved.

(Example) The present invention will be described below with reference to Examples. FIG. 1 is a schematic diagram of a paper feeding section in an electrophotographic copying machine that is an image forming apparatus. In the figure, IO is a photoreceptor drum, and the photoreceptor drum 10 is rotatable in the clockwise direction indicated by arrow A. During its rotation, the surface of the photosensitive drum 10 is uniformly charged by a charging device (not shown), and a predetermined original image is exposed onto the surface by an optical system (not shown), so that it becomes static. A latent image is formed. Thereafter, the electrostatic latent image on the photosensitive drum 10 is developed with toner in a developing device (not shown).

A recording paper 60 in a recording paper storage section 20 is conveyed to the photosensitive drum 10 through a recording paper conveyance path 30 in a paper feeding section. After the toner image on the photoreceptor drum 10 is transferred to the recording paper 60 by a transfer device 71, the recording paper 60 is separated from the photoreceptor drum 10 by a separation device 72.

A pickup roller 41 is disposed above the end of the recording paper storage section 20, and the pickup roller 41 picks up the recording paper 60 stored in the recording paper storage section 20 one by one. Sourced from within. A pair of paper feed roller 42 and separation roller 43 are arranged on the paper feed direction side of the pickup roller 41, and between both rollers 42 and 43, the paper feed from the paper feed cassette 20 is fed by the pickup roller 41. The recording paper 60 is conveyed. The paper feed roller 42 and the separation roller 43 are rotated such that the rotation directions of opposing portions are opposite to each other. As a result, the paper feed roller 42 introduces the recording paper 60 fed from the recording paper storage section 20 into the recording paper transport path 30, and
When a plurality of sheets of recording paper are fed in duplicate from the recording paper storage section 20, the separation roller 43 regulates the conveyance of the double-fed recording sheets.

In the recording paper conveyance path 30, in order from the recording paper storage section 2o side,
A first conveyance roller 31 and a second conveyance roller 32, each consisting of a pair of rollers, are arranged at an appropriate interval. Then, from the second conveying roller 32 to the photosensitive drum 10
Registration rollers 33, which are a pair of rollers, are arranged at an appropriate distance from each other.

Further, a third conveyance roller 34 consisting of a pair of rollers is disposed between the registration roller 33 and the photosensitive drum 10. Each of the rollers 31 to 34 is driven independently. The recording paper introduced into the recording paper conveyance path 30 is fed to the photoreceptor drum 10 by the first and second # feed rollers 31 and 32, the registration roller 33, and the third conveyance roller 34.

A first conveyance switch 51 is disposed immediately before the first conveyance roller 31 in the recording paper conveyance path 30, and
Immediately before the registration roller 33, a second transport switch 52 is installed.
is installed. Each transport switch 51 and 52 is
The switch is turned on when the recording paper conveyed in the recording paper transport path 30 reaches the respective arrangement position, and continues to be turned on until the recording paper passes through the respective arrangement position.

The operation of the paper feed section having such a configuration will be explained based on the time chart shown in FIG. 2, for example, when the same copy image is continuously formed on two sheets of recording paper. First, when the print key on the main body of the copying machine is operated, the drive motor rotates and the photosensitive drum 10 is rotated. Then, after the print key is turned on, a predetermined time period of about 5001IIS, for example, 1. Waiting for the lapse of time, the first and second conveyance rollers 31 and 32 are driven. When a predetermined time t1 of, for example, about 500 m5 has elapsed since the first and second conveyance rollers 31 and 32 were driven in this way, the paper feed roller 42 is rotationally driven together with the pickup roller 41 and separation roller 43, and the recording paper storage section is rotated. One recording paper 60 in 20 is fed into the recording paper conveyance path 30. After turning on the first conveyance switch 51, the recording paper 60 is conveyed toward the photosensitive drum 10 within the recording paper conveyance path 30 by the first conveyance roller 31. First transfer switch 5
When a predetermined time t2 has elapsed since the switch 1 is turned on, the drive of the paper feed roller 42 is stopped together with the pickup roller 41 and separation roller 43, and only one recording paper 60 is delivered from the recording paper storage section 20 to the recording paper transport path. 30.

The recording paper 60 conveyed in the recording paper conveyance path 30 by the first conveyance roller 31 reaches the position where the second conveyance roller 32 is disposed, and is transferred to the registration roller 33 by the second conveyance roller 32 and the first conveyance roller 31. transported towards.

Then, when a predetermined time t2 has elapsed after the leading edge of the recording paper 60 reaches the second conveyance switch 52 located immediately in front of the registration roller 33 and the second conveyance switch 52 is turned on, the second conveyance roller 32 is driven. will be stopped. As a result, the leading end of the recording paper 60 abuts against the registration roller 33 and is curved into a loop between the registration roller 33 and the second conveyance roller 32 .

At this time, the first conveyance roller 31 continues to rotate without being interrupted. Then, while the recording paper 60 is being fed to the registration rollers 33 as described above, when the trailing edge passes the position where the first conveyance switch 51 is disposed, the first conveyance switch 51 is turned off and the feeding Paper roller 42 is again driven together with pickup roller 41 and separation roller 43.

As a result, one sheet of recording paper 60 is newly fed from the recording paper storage section 20 into the recording paper transport path 30.

Then, the recording paper 60 is conveyed within the recording paper conveyance path 30, and after turning on the first conveyance switch 51, the recording paper 60 is conveyed by the first conveyance roller 31 toward the second conveyance roller 32.

When a predetermined time t2 has elapsed since the second subsequent recording paper 60 turned on the first conveyance switch 51, the paper feed roller 42
The pickup roller 41 and the separation roller 43 are turned off, and at the same time, the driving of the first* feed roller 31 is stopped. As a result, the leading edge of the succeeding recording paper 60 reaches the vicinity of the second conveyance roller 32 whose drive is stopped, and partially overlaps the trailing edge of the preceding recording paper 60 which has formed a loop. become.

As mentioned above, the preceding recording paper 60 is
When the second conveying roller 32 is stopped, the optical system for exposing the original image is operated to expose the original image. As a result, an electrostatic latent image corresponding to the original image is formed on the photoreceptor drum 10, and the electrostatic latent image is developed with toner. While the toner image is being formed on the photoreceptor drum 10 in this way, the succeeding recording paper 60 is conveyed as described above, and its leading edge is brought into contact with the trailing edge of the preceding recording paper in a loop shape. are overlapped.

In this way, while the toner image is being formed on the photoreceptor drum IO, the registration roller 33 and the conveyance roller 32 are driven in synchronization with the predetermined timing of rotation of the photoreceptor drum 10, and the registration roller 33 and the conveyance roller 32 are driven. The preceding recording paper 60, which has been formed into a loop by the roller 32, is
The registration roller 33 conveys the image to the photosensitive drum 10 via the third conveyance roller 34 . Then, while the preceding recording paper 60 comes into contact with the surface of the rotating photoreceptor drum 10 and the recording paper 60 moves together with the photoreceptor drum 10, the toner image on the drum 10 is transferred to the recording paper by the transfer device 71. 6
00 is transferred to a predetermined position.

At this time, the trailing recording paper whose leading end overlaps with the trailing edge of the preceding recording paper has not yet reached the position where the second conveyance roller 32 is disposed, so that it is necessary to transport the preceding recording paper. Even if the second conveyance roller 32 is driven together with the registration roller 33, the subsequent recording paper 60 is not conveyed. Then, the preceding recording paper 60 is conveyed, and its trailing end becomes the second i11i.
When the paper passes the position where the feed switch 52 is provided, the second feed switch 52 is turned off and the first feed roller 31 is driven. At this time, the driving of the second drive conveyance roller 32 continues without being stopped. Then, the subsequent recording paper is conveyed by driving the first conveyance roller 31 , and then the recording paper is conveyed toward the registration roller 33 by the second conveyance roller 32 . The registration rollers 33 are moved so that the rear end of the preceding recording paper 60 passes through the position where the 21st # feed switch 52 is disposed and the second transport switch 52 is turned off. The drive is stopped after a predetermined time L2 has elapsed. At this time, the scanning direction of the optical system is reversed and the optical system is scanned toward the home position.

Subsequent recording paper 6 being conveyed toward registration rollers 33
0 hits the registration roller 33 whose drive has been stopped, and is formed into a loop like the preceding recording paper 60.

Thereafter, this subsequent recording paper 60 is conveyed in the same manner as the preceding recording paper 60, and a toner image is formed at a predetermined position on the recording paper.

Note that when the number of copies is three or more, the leading edge of the third recording paper is overlapped with the rear end of the looped second recording paper in the same manner as described above.

(Effects of the Invention) In this way, when the same image is continuously formed on a plurality of sheets of recording paper, the paper feeding method of the image forming apparatus of the present invention is arranged so that when the same image is continuously formed on a plurality of sheets of recording paper, Since the leading end of the succeeding recording paper is superimposed on the edge, after the preceding recording paper is conveyed by the registration rollers, the succeeding recording paper is conveyed to the registration rollers in a very short time. Therefore, continuous conveyance of the recording paper can be made faster. In this case, since there is no need to increase the transport speed of the recording paper, the recording paper can be stably transported and noise generation can also be suppressed.

4 ゛のな曾゛■ Fig. 1 is a schematic diagram of the paper feed section of an electrophotographic copying machine used to carry out the method of the present invention, and Fig. 2 is a schematic diagram for explaining the operation of the paper feed section according to the method of the present invention. This is a timing chart.

10... Photosensitive drum, 20... Recording paper storage section, 3
0... Recording paper conveyance path, 31... Second conveyance roller, 3
2... Second conveyance roller, 33... Registration roller,
42... Paper feed roller, 51... First conveyance switch,
52...2nd vIj, forwarding switch.

that's all

Claims (1)

[Claims] 1. The recording paper fed through the conveyance path is temporarily stopped by a registration roller, and the recording paper is fed by the registration roller to an image carrier on which a predetermined image is formed. A paper feeding method for an image forming apparatus, the method comprising: transporting a subsequent recording sheet such that the leading edge of the preceding recording sheet overlaps the trailing edge of the preceding recording sheet stopped by a registration roller; and registering. When the preceding recording paper is fed to the image carrier by a roller, the preceding recording paper passes a predetermined position and is then conveyed until the subsequent recording paper comes into contact with a registration roller and stops. Forming device paper feeding method.