JPH0912198A - Paper sheet reversing device - Google Patents

Abstract

PURPOSE: To obtain high productivity and suppress a rise in noise and power consumption by reducing reasonably paper sheet interval in re-sending paper sheets to an image recording portion. CONSTITUTION: In a reversing roller device 100 comprising a first paper sheet reversing portion having a second roller 102 pressed to a first roller 101 and a second paper sheet reversing portion having a third roller 103 pressed to the first roller, the reversing rollers are rotated reversely so that sheets carried along sheet carrying path 104 are sent alternately to first or second paper sheet reversing portion by means of changeover of a changeover gate 107. And thus, while sending into a reversing portion is being made, sending out from other reversing portion is made. Accordingly, the carrying of paper sheets is stabilized, and also paper sheet interval is reduced, so that productivity is raised.

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 in an image forming apparatus such as a copying machine and a printer, and more particularly, when a sheet is discharged to a double-sided copying device or an output device,
The present invention relates to a sheet reversing device that reverses a sheet and retransmits it.

[0002]

2. Description of the Related Art Improvement of productivity of a sheet reversing device for reversing and conveying a sheet by means of forward and reverse rollers has been proposed in Japanese Utility Model Laid-Open No. 63-26659 and Japanese Patent Laid-Open No. 5-97305. In this type of paper reversing device, one of the pair of forward and reverse rollers can be brought into contact with and separated from the roller,
Since it is possible to allow the sheets to be overlapped and conveyed in the reverse conveyance path, it is possible to reduce the interval between the continuously conveyed sheets. However, as the paper size increases, the distance that the papers are overlapped and conveyed becomes longer, and the paper conveyance is likely to become unstable. Therefore, it is necessary to suppress the paper interval to the overlap of small size papers. For this reason, the larger the size of the paper, the lower the productivity. In order to improve this, it is necessary to increase the speed at the reversing unit, resulting in problems such as increased noise and power consumption. An object of the present invention is to reduce the paper interval without difficulty when retransmitting the paper to the image recording unit,
It is an object of the present invention to provide a sheet reversing device capable of achieving high productivity and suppressing increase in noise and power consumption.

[0003]

To achieve the above object, the present invention according to claim 1 provides a plurality of switches in a sheet reversing device provided in a sheet conveying path of an image forming apparatus or the like for reversing and retransmitting a sheet. A back mechanism and a paper transport path arranged toward the switchback mechanism, and sequentially feeds paper from the paper transport path to the switchback mechanism different from the switchback mechanism that has just been fed,
The structure is such that it is inverted and sequentially sent out. According to a second aspect of the present invention, in the first aspect of the present invention, the switchback mechanism includes a reversing roller including a second roller pressed against the first roller and a third roller pressed against the first roller. A device, wherein the roller device is configured to be capable of forward and reverse rotation, and alternately guides paper between the first roller and the second roller and between the first roller and the third roller in accordance with the forward and reverse operation. With this configuration, it is possible to continuously carry the sheet inversion conveyance.

According to a third aspect of the present invention, in the second aspect of the invention, a pair of rollers is provided upstream of the reversing roller device, a sheet detection sensor disposed near the rollers, and a downstream side of the sheet detection sensor. And a sheet conveyance direction switching gate arranged upstream of the reversing roller device, and alternately guides the sheet to the nip between the first roller and the second roller and the nip between the first roller and the third roller. In the configuration, a plurality of sheet conveying paths for guiding the sheet reversed by the reversing roller device are merged on the downstream side. According to a fourth aspect of the present invention, in the third aspect of the present invention, at least one of a plurality of sheet conveying paths for guiding the reversed sheet is provided with a sheet conveying direction switching gate that directly guides the sheet without passing through a reversing roller device. It is in a different configuration. Further, in the invention of claim 5, in the invention of claim 3, the paper conveyance direction switching for feeding the paper to at least one of the plurality of paper conveyance paths for guiding the reversed paper without performing the reversing operation of the reversing roller device. It is configured with a gate.

[0005]

According to the structure of the first aspect, the paper is sent to one of the plurality of switchback mechanisms, and the following paper is sent to the switchback mechanism different from the above. During the feeding operation to the different switchback mechanism, the sheet is sent out from the previous switchback mechanism. By causing the paper feed operation from another switchback mechanism during the paper feeding operation to a certain switchback mechanism as described above,
It is possible to stably convey the paper, and it is possible to improve productivity by reducing the paper interval. By using the reversing roller device including the second roller and the third roller, which are brought into pressure contact with the first roller by the switchback mechanism, the same effects as the above can be obtained with a simple structure. In addition, by adding a configuration for transporting the paper without the intermediary of the reversing roller device or a configuration for transporting the paper without performing the paper reversing operation of the reversing roller device in the switchback mechanism, a plurality of sheets can be provided on the same surface. It is possible to deal with a composition mode in which recording is performed once, and a device with high added value can be obtained.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. This embodiment is applied to an image forming apparatus configured as a printer. FIG. 5 shows a schematic configuration of this type of image forming apparatus. The apparatus main body 1 is equipped with paper feed trays 2 and 3 for accommodating sheets of various sizes, and a sheet reversing device 100 used in the double-sided mode or the combining mode, or when reversing and ejecting the sheets. Original image data sent from the outside is edited by the image processing device 4 to generate an image signal. On the other hand, the photoconductor 5 is charged by the charge corotron 6. Based on the image signal generated by the image processing device 4, a laser writing device (RO
S) 7 is used to write on the photoconductor 5 to form an electrostatic latent image of the original image. This electrostatic latent image is visualized by the developing device 8 to form a toner image. The transfer corotron 9 transfers the toner image onto the sheet conveyed at the timing of forming the toner image. After that, the paper is sent to the fixing device 10, and after the toner image is fixed, the paper is conveyed to the discharge tray 11 or the paper reversing device 100. After the toner image is transferred to the paper by the transfer corotron 9,
The toner remaining on the photoconductor is removed by the cleaner 12.

FIG. 1 shows the basic configuration of a sheet reversing device according to the present invention. The paper reversing device 100 is provided with a plurality of switchback mechanisms and a paper transport path arranged toward the switchback mechanism. The paper is alternately fed from the paper transport paths to the switchback mechanism and inverted to alternate. It is configured to send out. The switchback mechanism of the first embodiment includes a second forward / reverse rotation roller 102 (hereinafter referred to as a second roller) that is pressed against a first forward / reverse rotation roller 101 (hereinafter referred to as a first roller). Third forward / reverse rotation roller 103 (hereinafter referred to as the third roller) pressed against the first roller 101
A reversing roller device comprising: a reversing roller device;
By alternately guiding the paper between the first roller and the third roller, the paper can be continuously inverted and conveyed.

The upstream transport path of the switchback mechanism has a first paper transport path 105 and a second paper transport path 106 leading to the paper transport path 104, and the paper transport path 104 and the first and second paper transport paths. A sheet conveyance direction switching gate 107 for guiding the conveyed sheet to either the first or second sheet conveyance path is provided at the branch point of the paths 105 and 106. The sheet conveyed through the first sheet conveying path 105 is sent to the reversing sheet guide 108 by a roller pair including the first roller 101 and the second roller 102, and also conveyed through the second sheet conveying path 106. Is sent to the reversal sheet guide 108 by a roller pair including a first roller 101 and a third roller 103. The reversal sheet guide 108 is formed by the partition plate 121. The first reversal sheet guide 122 guides the sheet conveyed by the second roller side and the second reversal sheet guides the sheet conveyed by the third roller side. It is composed of a paper guide 123. The first roller 101 acts as a common roller for the sheets conveyed in the first sheet conveying path 105 and the second sheet conveying path 106.

A downstream side transport path 1 is provided outside the reverse sheet guide.
The third sheet conveyance path 110 leading to 09 is arranged,
Further, the reverse paper guide 108 is different from the third paper transport path 110.
A fourth sheet conveyance path 111 is arranged so as to face each other across the sheet and communicate with the same downstream side conveyance path 109. The upstream side of the third sheet conveying path 110 communicates with the downstream side of the first sheet conveying path 105, while the upstream side of the fourth sheet conveying path 111 communicates with the downstream side of the second sheet conveying path 106. , The sheet sent out from the reversing sheet guide 108 is fed to the merging portion of the first sheet conveying path 105 or the second sheet conveying path 106.
A first switching gate 112 and a second switching gate 113 for guiding the sheet are provided so as not to enter into, that is, toward the third sheet conveying path 110 or the fourth sheet conveying path 111. For example, when the first roller 101 is normally rotated as a driving roller, the second roller 102 side feeds the sheet to the first reversal sheet guide 122, and at the same time, the second roller 103 side moves from the second reversal sheet guide 123 to the first reversal sheet guide 123. It acts so as to send the paper to the fourth paper transport path 111. On the other hand, when the first roller 101 is rotated in the reverse direction, the sheet is conveyed in the opposite direction to the above, that is, the sheet is sent to the third sheet conveying path 110 by the third roller, and the sheet is conveyed by the second roller to the first sheet conveying path. 105 to the first reverse paper guide 1
The operation of sending to 22 is performed.

Based on a paper detection signal from a paper detection sensor 114 arranged upstream of the paper conveyance direction switching gate 107, the switching operation of the paper conveyance direction switching gate 107 and forward / reverse driving of each roller (paper reversing roller). Control is performed. Reference numerals 115 to 120 are sheet conveying rollers. In this embodiment, two switchback mechanisms have been described, but three or more switchback mechanisms may be used. Next, the control system of the sheet reversing device will be described. FIG.
In, the control unit selects a start switch signal for starting image recording, a mode key for retransmitting the paper to the image forming unit during image recording such as double-sided mode or composite mode, or after recording an image on the paper. The paper reversal control is started based on the key operation signal when the mode key for reversing and discharging is selected. Set the timer value based on the detection signal of the paper detection sensor,
The drive control of the sheet conveyance direction switching gate, the conveyance roller and the forward / reverse rotation roller is performed.

The operation of the sheet reversing device will be described with reference to FIG. When the paper reversing operation starts, the first roller rotates in the normal direction (S1), and the second roller side starts the paper feeding operation. When the paper detection sensor detects ON or OFF and the front end or the rear end of the paper is detected (S2, S3), the paper conveyance direction switching gate is driven to switch to the a side or the b side shown in FIG. 1 (S4). At this time, the timer is set to Ta = 0 (S5). When the timer value Ta has passed Ta1 (S6), the first roller is rotated in the reverse direction (S7), and the sheet sent to the reverse sheet guide is sent to the third or fourth sheet conveying path. That is, the timer value Ta1 is fed to the reversing paper guide so as to be guided from the rear end side of the paper sent through the first or second paper transport path to the third or fourth paper transport path. Set enough time. When the first roller rotates in the reverse direction (S7), the sheet sent to the reverse sheet guide is sent from the rear end to the third or fourth sheet conveying path. At this time, the timer is set to Tb = 0 (S8), and after this timer value Tb = Tb1 has elapsed (S8).
9) Judge the copy signal, and if the copy is not completed, return to step S1 to perform the subsequent paper reversing operation.

FIG. 4 shows a timing chart during the paper reversing operation. Here, the first roller, the second roller, and the third roller are collectively referred to as a sheet reversing roller. When the sheet reversing roller is rotated in the forward direction, the trailing edge of the sheet passes the transport roller, and when the sheet detection sensor detects the trailing edge of the sheet, the sheet transport direction switching guide is switched from position a to position b. The next sheet is detected by the sheet detection sensor, and when a predetermined time elapses, the driving of the sheet reversing roller is stopped, the timer value Tb1 is set, and the sheet is reversed. When the trailing edge of the next sheet is detected, the sheet conveyance direction switching guide is switched from the position b to the position a, and the conveyance direction of the next sheet, that is, the conveyance path different from the conveyance path of the preceding sheet is switched. When the timer value Tb1 has elapsed, the paper reversing roller is stopped, and then the normal rotation operation is started. By the normal rotation of the sheet reversing roller, the sheet conveyed when the sheet conveyance guide switching gate is at the position b is sent to the sheet guide by the sheet reversing roller. When the paper reversing roller rotates in the normal direction, the timer value Ta1 is set, and the paper conveyed at the position a of the paper conveyance direction switching guide is sent to the paper guide. By repeating this operation, it is possible to stably convey the sheet even between short sheets.

Next, the operation of this embodiment will be described. In FIG. 6, before the sheet is conveyed, the sheet conveying direction switching gate is located at the position b.
Therefore, the paper reversing roller is driven to rotate normally. In this state, the sheet is fed to the reversing sheet guide by the first roller and the second roller through the first sheet conveying path (FIG. A → FIG. B). When the paper detection sensor detects the trailing edge of the paper, the paper transport direction switching gate switches to the position a (FIG. C). While the next sheet is passing through the second sheet conveying path, the sheet reversing roller is stopped from the forward rotation, and is driven in the reverse direction at the sheet conveying timing (Fig. C → Fig. D). Then, the paper is sent to the third paper transport path, and at the same time, the paper is sent to the reverse paper guide by the first roller and the third roller. When the trailing edge of the paper is detected during the paper feeding operation, the paper transport direction switching gate is switched to the position b (FIG. E).

In FIG. 7, while the sheet is passing through the first sheet conveying path, the sheet reversing roller is driven in the forward direction to feed the sheet to the fourth sheet conveying path and guide the sheet to the reversing sheet guide. Feeding is performed (Fig. E → Fig. F). By the next reverse rotation drive of the paper reverse roller, the paper is sent to the third paper transport path and the paper is sent to the reverse paper guide (FIG. G). In this process, the paper is conveyed to the common conveyance path connected to the downstream side of the switchback mechanism, and the paper is conveyed to the common conveyance path during the feeding of the paper to the reverse paper guide (Fig. G). → Figure h). As described above, while the paper is being sent from the reverse paper guide to one of the paper guides, the following paper is sent to the reverse paper guide, and when the following paper is sent to the reverse paper guide, the subsequent paper is transferred to the other paper guide. By feeding the paper to the paper guide, the distance between the papers can be reduced, and the papers are not overlapped and conveyed in the conveyance path. Therefore, the paper conveyance can be stabilized and the productivity can be improved.

Next, a second embodiment of the present invention will be described. FIG. 8 shows the configuration of the paper reversing device of the second embodiment. In this embodiment, the paper reversing function of the first embodiment is provided with a non-reversing function of conveying the paper without reversing it. A fifth conveyance path 121 is provided for guiding the sheet conveyed by the conveyance rollers 115 directly to the sheet conveyance path 110 without sending it to the reverse sheet guide 108. A second sheet conveyance direction switching gate 122 is arranged to guide the sheet to the fifth conveyance path 121. The second sheet transport direction switching gate 122 is opened and closed so that the sheet can be transported to the fifth transport path 121 when the first sheet transport direction switching gate 107 is at the position b. In other words, the second sheet transport direction switching gate 122 causes the fifth transport path 121 to move.
When the sheet is closed, the first sheet transport direction switching gate 10
The switching operation of 7 can be performed.

In the synthesizing mode, the images are recorded on the same side of the sheet in several times so that the sheets are overlapped and recorded. Therefore, it is necessary to convey the sheet to the photoconductor again for each image recording. When this combination mode is selected, the second sheet conveyance direction switching gate 122 is switched to the position shown by the solid line in the figure, and the fifth conveyance path 121 is opened. The conveyed sheet passes through the fifth conveying path 121, enters the third sheet conveying path 110 in this example, and is conveyed from there to the common conveying path 109. FIG. 9 shows a modified configuration of the second embodiment. In this embodiment, the second sheet conveyance direction switching gate is arranged immediately after the sheet reversing roller, and when the sheet reversing roller is driven to rotate normally, the third sheet is not reversed by the sheet reversing rollers 101 and 102. A fifth transport path 121a for transporting to the transport path 110 is provided. That is, when the combination mode or the sheet reverse ejection mode is selected, the first sheet conveyance direction switching gate 107 is set to the position b,
The second sheet conveyance direction switching gate 122a is switched from the position c to the position d. As a result, the paper reversing roller 101,
The sheet fed into the reversal sheet guide 108 at 102 is guided to the second sheet conveyance direction switching gate 122a, and guided to the third sheet conveyance path 110 through the fifth conveyance path.

[0017]

As described above, according to the present invention, in accordance with the forward / reverse operation of the plurality of pressure-contacting rollers which constitute the plurality of switchback mechanisms, the rollers are sequentially fed into the plurality of switchback mechanisms to invert the sheet and feed it out. Therefore, it is possible to reduce the paper interval without difficulty, and it is possible to obtain high productivity. Further, the sheet interval can be reduced without increasing the speed in the reversing unit, which is advantageous for noise and power consumption.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a first embodiment of a sheet reversing device according to the present invention.

FIG. 2 is a block diagram of a control system of the sheet reversing device.

FIG. 3 is a flowchart illustrating a paper transport operation of a control system.

FIG. 4 is a timing diagram showing the operation timing of the control system.

FIG. 5 is a diagram showing an example in which the sheet reversing device of the present invention is actually applied to an image forming apparatus.

FIG. 6 is an explanatory diagram of the operation of the sheet reversing device.

FIG. 7 is an operation explanatory diagram following FIG. 6;

FIG. 8 is a configuration diagram showing a second embodiment of the sheet reversing device.

FIG. 9 is a configuration diagram showing a modification of the second embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2, 3 ... Paper feeding tray, 4 ... Image processing apparatus, 5 ... Photoconductor, 7 ... Laser writing apparatus, 100 ... Paper reversing device, 101-103 ... Paper reversing roller, 105 ...
First paper transport path, 106 ... Second paper transport path, 107
... Paper transport direction switching gate, 108 ... Reverse paper guide,
110 ... Third paper transport path, 111 ... Fourth paper transport path, 112, 113 ... Switching gate, 114 ... Paper detection sensor, 115-120 ... Transport rollers, 121, 121a
... fifth paper transport path 122, 122a ... second paper transport direction switching gate

Claims (5)

[Claims] 1. A paper reversing device provided in a paper conveyance path of an image forming apparatus or the like for reversing and retransmitting paper, comprising a plurality of switchback mechanisms and a paper conveyance path arranged toward the switchback mechanism. A sheet reversing device comprising: a sheet reversing device configured to sequentially feed the sheets from the sheet conveying path to a switchback mechanism different from the switchback mechanism that is fed immediately before, reverse the sheets, and sequentially deliver the sheets. 2. A switchback mechanism is a reversing roller device composed of a second roller pressed against the first roller and a third roller pressed against the first roller. It is configured to be reversible, and it is possible to continuously reverse the paper by guiding the paper alternately between the first roller and the second roller and between the first roller and the third roller with the forward and reverse operation. The sheet reversing device according to claim 1, wherein 3. A pair of rollers on the upstream side of the reversing roller device, a paper detection sensor arranged near the rollers, and a paper arranged on the downstream side of the paper detection sensor and on the upstream side of the reversing roller device. It is provided with a transfer direction switching gate and alternately guides the paper to the nip between the first roller and the second roller and the nip between the first roller and the third roller, and guides the paper reversed by the reversing roller device. 3. The sheet reversing device according to claim 2, wherein the plurality of sheet conveying paths are merged on the downstream side. 4. A sheet conveying direction switching gate for directly guiding the sheet without passing through a reversing roller device is provided in at least one of a plurality of sheet conveying paths for guiding the reversed sheet. Paper reversing device. 5. A paper conveyance direction switching gate for feeding the paper without performing the reversing operation of the reversing roller device is provided in at least one of the plurality of paper conveyance paths for guiding the reversed paper. The sheet reversing device according to item 3.