JPH09255204A - Inverter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a carrying failure even if a transfer paper sheet with a tab is carried being mixed in normal transfer paper sheets in a device for inverting transfer paper sheets and carrying these sheets. SOLUTION: In an inverter for carrying a transfer paper sheet from a first route A into a second route B and then reverse-carrying the same so as to send it to the downstream side of the first route, a sensor 6 provided in the upstream side of a branching point for detecting the rear end position of the transfer paper sheet, a driving roller 3 for reverse-carrying the transfer paper sheet carried into the second route and a follower roller 4 rotationally contacted with the driving roller based on a signal from the sensor 6 are positioned in the width direction of the transfer paper sheet. Also, if a transfer paper sheet with a tab is carried in while its tab position is placed in a rear end side, since the driving roller 3 for reverse-carrying the transfer paper sheet and the follower roller 4 are brought to the tab position, this transfer paper sheet is carried with the same operational timing as that of normal transfer paper sheets.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reversing device for reversing and conveying a transfer sheet in an image forming apparatus such as a copying machine or a printer.

[0002]

2. Description of the Related Art A conventional reversing device of this type is disclosed in Japanese Utility Model Laid-Open No. 60-61241.
That is, a drive roller for reversely feeding the transfer paper is provided in the conveyance path for inverting the transfer paper branched from the main path, so that the transfer paper is reversely fed and sent to the downstream side of the main path. There is. The timing signal for driving the drive roller is given by a sensor provided near the branch point from the main path. The sensor detects the trailing edge of the transfer sheet sent to the reversing path and sends a timing signal to the control unit. Upon receipt of this timing signal, the control unit drives the drive roller after a time such that the transfer sheet is completely carried into the reversing path, and causes the transfer sheet to be fed backward.

[0003]

In the above-mentioned conventional reversing device, the sensor detects the trailing edge of the transfer sheet as described above, and the operation timing of the conveyance by the drive roller is determined by the detection timing. On the other hand, in recent years, with the diversification of requests from users for copying machines, tabbed transfer paper as shown in FIG. 4 may be used. When the tabbed transfer paper is conveyed with the tab T as the rear end, there is a problem that the operation timing of the drive roller changes depending on the installation position of the sensor and conveyance failure occurs. That is, the sensor is installed in the center of the route,
If the drive rollers are located on both sides of the transport,
The drive timing of the transfer paper with the tab is later than the drive timing of the normal transfer paper without the tab, and the transfer paper is sent before the drive roller, which may cause conveyance failure.

Therefore, according to the present invention, by arranging the position of the sensor and the driving roller, even when such a transfer paper with a tab is mixedly conveyed with a normal transfer paper, the conveyance failure does not occur. The purpose is to provide a device.

It is another object of the present invention to provide a reversing device capable of performing a stable reversing operation without skew when the transfer paper is fed backward.

[0006]

According to a first aspect of the present invention, there is provided a reversing device having a first path for conveying a transfer sheet and a second path branched from the first path. In the transfer paper reversing device, the transfer paper from the first path is once carried into the second path, and then the paper is sent back to the downstream side of the first path. Second
A sensor provided on the upstream side of the branch point from the path for detecting the rear end position of the transfer sheet, and the transfer sheet from the first path is carried into the second path and the transfer of the second path is performed. A branch claw that carries out the paper to the downstream side of the first path, a drive roller for feeding back the transfer paper carried into the second path, a driven roller that is in rolling contact with the drive roller, and the sensor. And a drive unit for moving the driven roller to and from the drive roller based on a signal from the sensor, the position of the sensor, the drive roller, and the driven roller in the width direction of the transfer sheet are aligned.

A second aspect of the present invention is characterized in that the sensor, the driving roller and the driven roller are positioned at the center of the first and second paths in the width direction.

According to the third aspect of the present invention, a plurality of the driving rollers and the driven rollers are provided, and the driving rollers and the driven rollers are arranged at symmetrical positions in the width direction of the second path.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view of an embodiment of a reversing device according to the present invention. In the figure, reference numeral 1 denotes a conveyance roller installed on the first conveyance path A, and is rotated so as to feed the transfer sheet from the left side to the right side in the figure. Reference numeral 2 denotes a branch claw, which is installed at a branch point between the first transport path A and the second transport path B. The branching claw 2 is switched between two states, and in the first state shown in FIG. 1, the transfer sheet sent from the upstream side of the first transporting path A is moved straight at the branching point to the first transporting path A. Can be transported to the downstream side of. Further, in the second state shown in FIG. 2, the transfer sheet sent from the upstream side of the first conveyance path A can be conveyed to the second conveyance path B, and as shown in FIG. The transfer paper on the transport path B of the first
It is possible to carry the paper to the downstream side of the carrying path A.

In the figure, 3 is a driving roller, and 4 is a driven roller, which rotates so as to convey the transfer paper in the second conveying path B to the downstream side (right side in the drawing) of the first conveying path A. . That is, the driving roller 3 and the driven roller 4 are rotated so as to convey the transfer sheet in the direction opposite to the direction in which the transfer sheet is carried into the second conveyance path B. The driven roller 4 is operated by the solenoid 5 so as to come into contact with and separate from the drive roller 3. When the transfer sheet is carried into the second transport path B, the driven roller 4 is separated from the drive roller 3 as shown in FIGS. 1 and 2. Further, when the transfer paper is carried out from the second carrying path B to the first carrying path, as shown in FIG.
The driven roller 4 is brought into contact with the driving roller 3 and follows the driving roller 3.

In the figure, reference numeral 6 denotes a sensor, which is installed upstream of the branch point of the first transport path A. The sensor 6 is configured such that the transfer paper transported in the first transport path A is
When the sheet is sent to the conveyance path B side of, the rear end is detected. The solenoid 5 that moves the driven roller 4 is operated based on the detection signal of the sensor 6.

When the branch claw 2 moves from the state shown in FIG. 1 to the state shown in FIG. 2 and the second conveyance path B is released, the transfer paper sent through the first conveyance path A is transferred to the second conveyance path. It is transported into B. When the trailing edge of the transfer paper passes the sensor 6, the sensor 6 detects this and sends a control signal to the control unit. The control unit drives the solenoid 5 and sends the driven roller 4 to the drive roller 3 side after a lapse of time until the rear end of the transfer sheet is sent to the upper side of the branching claw 2. The transfer sheet is sandwiched between the driving roller 3 and the driven roller 4, is fed in the carrying-in direction, and is discharged to the downstream side of the first transport path A as shown in FIG.

When the tabbed transfer paper as shown in FIG. 4 is used in the reversing device with the tab T side as the rear end, the rear end position differs between the portion with the tab T and the portion without the tab T. Here, assuming that the sensor 6 is provided at the position where the tab is provided (that is, the center of the transport path) and the drive roller 3 and the driven roller 4 are provided at the position where the tab is not provided (that is, both sides of the transport path) as in the conventional case.
The sensor 6 delays the trailing edge detection by the height of the tab as compared with the normal transfer paper. Therefore, the drive timing of the solenoid 5 is also delayed, and the transfer sheet may be fed into the second transport path B beyond the positions of the drive roller 3 and the driven roller 4, resulting in poor transport. Further, when the sensor 6 is provided at a position where there is no tab (that is, both sides of the transport path), the solenoid 5
Operates at the same timing as normal transfer paper, but in this case, the tab operates before being completely fed into the second transport path B, and there is a risk that the tab may be caught by the branch claw 2.

Therefore, in this embodiment, the sensor 6,
The drive roller 3 and the driven roller 4 are arranged in alignment with the widthwise centers of the first and second transport paths A and B. Therefore, the detection of the trailing edge of the tabbed transfer sheet by the sensor 6 is delayed as compared with the case of the normal transfer sheet, but since the drive roller 3 and the driven roller 4 are arranged at the center, these are the tab positions of the transfer sheet. The transfer paper can be fed back.

Further, in the present embodiment, in addition to the pair of the driving roller 3 and the driven roller 4 provided at the center, the pair of the driving roller and the driven roller are installed at symmetrical positions on both sides in the width direction of the transport path. You can also By arranging these rollers symmetrically with respect to the center of the transport path, it is possible to eliminate skew when the transfer paper is fed backward.

FIG. 5 is a timing chart showing the operation timing of the solenoid 5 with respect to the output of the sensor 6.
As shown in FIG. 5, when the sensor 6 detects the front end of the transfer sheet and the switch is turned on, and then the rear end of the transfer sheet is detected and the switch is turned off, the sensor 6 outputs a detection signal to the control unit ( (Not shown). The controller turns on the solenoid 5 after a time t sufficient for the rear end of the transfer sheet to pass through the front of the sensor 6 and to be completely carried into the second transport path B. The solenoid 5 is driven at the same timing regardless of whether the transfer sheet to be conveyed is a normal one or a tabbed one.

FIG. 6 is a block diagram showing an example of control according to the present invention. In the figure, reference numeral 7 denotes a microprocessor as a control unit, which executes control of the entire image forming apparatus. Reference numeral 8 is a ROM (read only memory) for storing control programs and the like, and 9 is a RAM (random access memory) for storing various flags, data and the like. The detection signal from the sensor 6 is sent to the microprocessor 7 via the I / O interface 10, and when the microprocessor 7 receives the detection signal from the sensor 6, the I / O interface 10, D
The solenoid 5 is driven via the C driver 11.

[0018]

As described above, in the reversing device according to the first aspect of the present invention, the position of the sensor and the positions of the driving roller and the driven roller for feeding the transfer sheet in the reverse direction are matched in the width direction of the conveying path. Even when the tabbed transfer paper is reversed, the drive roller and the driven roller operate in good timing, and there is an effect that conveyance failure is not caused.

In addition to the effect of the first aspect, the reversing device of the second aspect has the sensor, the driving roller and the driven roller located at the center in the width direction of the conveying path, so that the reversing operation of the transfer sheet is stable and has no skew. There is an effect that it becomes possible.

In addition to the effect of the second aspect, the reversing device of the third aspect is provided with a plurality of the driving rollers and the driven rollers and is arranged at symmetrical positions in the width direction of the second path, so that there is no more stable skew. There is an effect that the inversion operation becomes possible.

[Brief description of drawings]

FIG. 1 is a side view of an embodiment of a reversing device according to the present invention.

FIG. 2 is a side view showing a state in which a transfer sheet is carried into a second transport path.

FIG. 3 is a side view showing a state in which a transfer sheet is reversely fed and carried out from a second transport path.

FIG. 4 is a plan view showing a transfer sheet with a tab.

FIG. 5 is a timing chart showing the operation timing of the solenoid with respect to the output of the sensor.

FIG. 6 is a block diagram showing an example of control of the present invention based on a detection signal of a sensor.

[Description of Reference Signs] A first transport path B second transport path 1 transport roller 2 branching claw 3 drive roller, 4 driven roller 5 solenoid 6 sensor 7 microprocessor 8 ROM 9 RAM 10 I / O interface 11 DC driver

Claims (3)

[Claims] 1. A first path for conveying a transfer sheet, and the first path.
Of the transfer paper which has a second path branched from the above-mentioned path, and once the transfer paper from the above-mentioned first path is carried into the second path and then is fed back and sent to the downstream side of the above-mentioned first path. In the reversing device, a sensor provided on the upstream side of a branch point of the first path from the second path to detect a rear end position of the transfer sheet, and the transfer sheet from the first path to the second path And a drive roller for feeding the transfer paper of the second path to the downstream side of the first path and for feeding back the transfer paper of the second path. A driven roller that rolls into contact with the drive roller, and a drive unit that moves the driven roller toward and away from the drive roller based on a signal from the sensor, and the sensor, the drive roller, and the driven roller in the width direction of the transfer sheet. Inversion characterized by matching the position of the rollers Location. 2. The reversing device according to claim 1, wherein the sensor, the driving roller, and the driven roller are located at the center of the first and second paths in the width direction. 3. The reversing device according to claim 2, wherein a plurality of the driving rollers and the driven rollers are provided and are arranged at symmetrical positions in the width direction of the second path.