JPH0891637A - Sheet carrying device - Google Patents

Abstract

PURPOSE: To eliminate the bad influence to the transfer independently of size and stiffness of the paper sheet. CONSTITUTION: A loop housing chamber for housing a loop of a rolled paper is formed at a part of a sheet carrying passage 2, namely, in the upstream side of a resist roller 4. This loop housing chamber is formed of an opening and closing baffle 7, a lever 13 supported by a supporting shaft 11, a turntable 14 having a pin 15, a sensor 16 for detecting position of the turntable 14. The opening and closing baffle 7 is closed until the tip of the rolled paper 18 achieves the resist roller 4, and when the tip of the rolled paper 18 abuts on the resist roller 4, it is opened. Loop of the rolled paper 18 is thereby housed in the opened opening and closing baffle 7, and for example, bad influence of the collision at the time of cutting by a cutter 8 or the buckling generated in the paper sheet with low stiffness to a transfer part 3 can be prevented so as to prevent the missing of transfer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device of an image forming apparatus, and more particularly to a sheet conveying device for cutting a roll paper to an arbitrary length by a cutter while conveying it toward a registration roller and an image transfer portion.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a printer, in order to align an image (latent image) formed on a photosensitive drum with a copy sheet, a sheet sent is sent. A registration roller is arranged in front of the transfer device to stop the transfer, measure the timing, and send out. As is well known, the registration roller controls the feeding and stopping of the paper by repeating the rotation and the stopping.

When a sheet is temporarily stopped by the registration roller, a loop is formed on the upstream side of the sheet. Therefore, the registration roller and the registration roller are conventionally used, as disclosed in, for example, Japanese Patent Publication No. 4-18303. An accommodation space for the loop is provided between the conveying rollers arranged on the upstream side. The configuration of a conventional sheet conveying device having this accommodation space will be described with reference to the configuration diagram of FIG.

In the figure, 1 is a photosensitive drum, and 2
Is a transport path for transporting roll paper (not shown).
3 is a transfer unit, 4 is a registration roller drive roller, 4'is a driven roller, 5 is a first transport roller drive roller, 5'is a driven roller, 6 is a second transport roller drive roller, and 6'is a driven roller. , 8 is a roll paper cutter, 9 is a first sensor for detecting the leading end of the roll paper, and 10 is a second sensor. Reference numeral 21 is an opening / closing baffle made of an elastic member for forming the accommodation space, and is configured to elastically rotate clockwise about a fulcrum 22. As another prior art related to the present invention, for example, there is one disclosed in Japanese Utility Model Laid-Open No. 2-7660.

[0005]

When roll paper is fed from a roll paper feeding device (not shown) to the sheet transporting device having the above-mentioned structure, the roll paper is fed by the first transport rollers 6, 6 ', and the second transport rollers. Are transported by the transport rollers 5, 5'of
The tip reaches the registration rollers 4, 4 '. When the roll paper is further conveyed, the roll paper is transferred to the registration rollers 4 and 4.
′ And the second transport rollers 5, 5 ′ form a loop,
The open / close baffle 21 is pushed up by the loop and rotates clockwise. As a result, the loop is accommodated in the space formed by the opening / closing baffle 21. For large size roll paper (for example, A1 size),
The roll paper is cut by the cutter 8 while being transferred by the transfer unit 3 through the registration rollers 4 and 4 ′.
At this time, the loop absorbs a shock given to the roll paper and prevents the shock from being transmitted to the transfer portion.

However, in this conventional apparatus, since the space for accommodating the loop is small, it is not possible to sufficiently absorb the impact given to the roll paper at the time of cutting the roll paper. Further, the loop shape changes depending on the strength of the waist of the roll paper, and a loop-like small deformation, that is, buckling occurs in the sheet having a weak waist. The impact or buckling reaches the transfer section 3, so that the transfer section 3 does not perform stable transfer, which may cause image loss.

An object of the present invention is to eliminate the above-mentioned problems of the prior art, and to provide a sheet conveying apparatus which does not adversely affect the transfer regardless of the size of the paper such as roll paper or the strength of the waist. To provide.

[0008]

In order to achieve the above-mentioned object, the invention of claim 1 suspends a sheet sent on a sheet conveying path and synchronizes with an image formed on an image forming apparatus. In a sheet conveying device having a registration roller for sending out the sheet, a nip of at least one conveying roller which is opened to accommodate a loop generated when the sheet is stopped and which is upstream of the registration roller when the sheet is opened. It is characterized in that it is equipped with an open / closed conveyance path for releasing.
Further, the invention of claim 2 further comprises a sensor for detecting passage of the leading edge of the sheet, and control means for closing the opening / closing conveying path when the leading edge of the sheet passes and opening the opening / closing conveying path when a loop is formed. Is characterized by.

[0009]

According to the invention of claim 1, the loop accommodating chamber formed by the open / close transfer path is considerably large. For this reason, the loop formed by stopping the sheet can be enlarged, and for example, the impact generated when the cut sheet is cut is sufficiently absorbed by the loop. Further, it is possible to prevent buckling of a paper having a weak stiffness, which occurs when a loop is formed in a conventional small loop storage chamber. As a result, it is possible to prevent transfer omission in the transfer portion, and it becomes possible to perform good copying. Also,
According to the second aspect of the present invention, the opening / closing of the opening / closing conveyance path can be controlled in accordance with the advance of the leading edge of the sheet, so that the sheet can be conveyed reliably without causing a sheet jam. it can.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing the configuration of a sheet conveying apparatus according to an embodiment of the present invention. 4 which are the same as those in FIG. 4 indicate the same or equivalent components. The open / close conveyance path 7 (hereinafter referred to as the open / close baffle 7) is attached rotatably around a fulcrum 11 and is held at a predetermined position by a spring 12. The open / close baffle 7 is integrally attached with a driven roller 5'of a first conveying roller. A lever 13 that rotates integrally with the opening and closing baffle 7 is attached to the fulcrum 11, and a rotating plate 14 having a pin 15 for swinging the lever 13 is pivotally supported near the lever 13. There is. The rotational position of the rotary plate 14 is detected by the third sensor 16. The rotary plate 14 is configured to rotate in the direction of arrow a every half rotation.

FIG. 1 shows a state in which the opening / closing baffle 7 is closed, and FIG. 2 shows a state in which the opening / closing baffle 7 is open. As is apparent from the figure, when the rotary plate 14 is rotated in the direction of arrow a, the lever 13 is pressed clockwise by the pin 15 and rotates in the same direction against the pulling force of the spring 12. As a result, the opening / closing baffle 7 opens as shown in FIG. Further, when the rotary plate 14 is rotated in the direction of arrow a, the lever 13 is retracted counterclockwise by the pulling force of the spring 12. Therefore, the opening / closing baffle 7 is closed as shown in FIG.

The third sensor is, for example, a transmissive sensor, and is composed of, for example, a light emitting element and a light receiving element which are arranged to face each other. Then, when the light receiving element detects light, it is determined that the rotary plate 14 is in the state of FIG.
On the other hand, when the light receiving element does not detect light, it is determined that the rotary plate 14 is in the state shown in FIG. The rotary plate 14 is turned on / off by a stepping clutch (not shown), and stops half a turn (180 °) every time a signal is input to the stepping clutch.

Next, the operation of this embodiment will be described with reference to the timing chart of FIG. The figure shows timing signals for the operations of the first and second sensors 9 and 10, the stepping clutch that transmits rotational power to the rotary plate 14, the open / close baffle 7, the registration roller 4, and the cutter 8.

Roll paper 1 from a controller not shown
When an instruction to copy an image is issued to the image forming device 8, the registration rollers 4, 4 ', the first conveying rollers 5, 5', the second conveying rollers 6, 6 ', and the photoconductor 1 have substantially the same peripheral speed. To rotate. Then, the roll paper 18 delivered from the roll paper feeding device (not shown) passes through the cutter unit 8 and is guided into the roll paper transport path 2.

Next, at time t1, when the first sensor 9 detects the leading edge of the roll paper 18, a signal is applied to the stepping clutch. As a result, power is transmitted to the rotary plate 14, and the rotary plate 14 rotates half a turn. By this half rotation, the pin 15 pushing up the lever 13 moves, and the pulling force of the spring 12 closes the open / close baffle 7 that has been open until now, forming a sheet conveying path. As a result, the leading end of the roll paper 18 passes through the open / close baffle 7 and is guided to the registration rollers 4, 4 '.

Next, at time t2, when the second sensor 10 detects the leading edge of the roll paper, the leading edge of the roll paper passes through the nip between the registration rollers 4 and 4 ', and the first distance advances a minute distance. After a predetermined time T1, a signal is applied to the stepping clutch. As a result, the opening / closing baffle 7 starts to open, and the roll paper comes into contact with the registration rollers 4 and 4'and accommodates a loop formed. When the opening / closing baffle 7 is opened, a large loop of about 30 mm can be absorbed.

At time t3, which is the second predetermined time T2 after time t1, the registration rollers 4 and 4'are temporarily stopped. For this reason, the roll paper is opened and closed by the baffle 7
Form a loop inside. After that, when a signal is input to the registration roller 4 in synchronism with the image on the photoconductor 1, the registration roller 4 rotates and sends the roll paper 18 to the transfer unit 3. The loop amount generated during the third predetermined time T3 from the temporary stop of the registration rollers 4 and 4 ′ to the re-rotation reaches about 30 mm in roll paper conveyance amount, and this loop has a predetermined sheet length. After being conveyed, it is held until it is cut by the cutter 8. The opening and closing baffle 7 of this embodiment is
As is clear from FIG. 2, the nip of the first transport rollers 5 and 5 ′ is released, and the registration rollers 4, 4 ′ and the second transport rollers 6 and 6 ′ form a loop accommodation space.
It can provide a large space.

When the roll paper 18 reaches the transfer portion 3 and a drive signal is applied to the cutter 8 at time t4 during transfer, the cutter 8 cuts the roll paper 18. At this time, the roll paper 18 is pulled in the direction opposite to the traveling direction, and the cutting impact is transmitted to the roll paper in progress. However, since the opening / closing baffle 7 of this embodiment can accommodate a large loop as described above, the shock at the time of cutting can be absorbed by the loop. Therefore, the impact when the roll paper 18 is cut does not reach the leading end of the paper of the transfer unit 3. Even if the paper is weak, the large loop prevents the paper from buckling. As a result, the transfer unit 3 can perform good transfer without transfer omission. Furthermore, according to the present embodiment, excessive buckling of the sheet does not occur, so that paper jam due to this does not occur.

At time t5, the trailing edge of the roll paper 18 passes the first sensor 9. Then, at the time t6, when the leading edge of the next roll paper is detected, a signal is applied to the stepping clutch, and the rotary plate rotates half a turn. Therefore, the opening / closing baffle 7 is closed again. In the case of the image forming mode of a plurality of sheets, after the roll paper is cut by the cutter 8, the next roll paper 18 is further fed, and the above operation is repeated.

In this embodiment, when the paper is jammed, the opening / closing baffle 7 is opened so that the operation of the sheet conveying device is completed. Therefore, the paper jam can be easily removed.

In the above description of the embodiment, the case where roll paper is conveyed has been described, but the present invention is not limited to this, and it goes without saying that it may be applied to a conveyance path for cut paper.

[0022]

According to the first aspect of the present invention, since the nip of at least one conveying roller upstream of the registration roller can be released to form the loop storage chamber for the sheet, a large loop storage chamber can be formed. effective. Further, as a result, it is possible to absorb the impact when the paper is cut with a large loop, or it is possible to almost completely prevent the buckling that has occasionally occurred in the prior art on paper with a weak stiffness when forming a loop. You will be able to guarantee a good transcription of.

According to the second aspect of the present invention, the passage of the leading edge of the sheet can be detected to control the opening / closing of the open / close conveying path, so that the sheet is prevented from being jammed by the opening / closing of the open / close conveying path. Therefore, it is possible to provide a highly reliable sheet conveying device.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a first operation state of an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a second operation state of the present embodiment.

FIG. 3 is a timing chart showing the operation of this embodiment.

FIG. 4 is an explanatory diagram showing a configuration of a conventional device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoconductor, 2 ... Roll paper conveyance path, 3 ... Transfer part, 4 ... Registration roller, 5 ... 1st conveyance roller, 6 ... 2nd conveyance roller, 7 ... Opening / closing baffle, 8 ... Cutter, 9 ... 1 sensor, 10 ... second sensor, 13 ... lever, 14
… Rotating plate, 15… Pin, 16… Third sensor, 18…
Roll paper.

Claims (1)

[Claims] 1. A sheet conveying apparatus including a registration roller for temporarily stopping a sheet fed on a sheet conveying path and feeding the sheet in synchronism with an image formed on an image forming apparatus. The sheet conveying apparatus is provided with an opening / closing conveying path that is opened to accommodate a loop generated when the sheet is stopped, and that releases the nip of at least one conveying roller upstream of the registration roller when the loop is opened.