JPH0540374A - Form inverting mechanism of image formation device - Google Patents

Abstract

PURPOSE:To securely prevent a form from jamming when turned over. CONSTITUTION:An inversion lever 17 is coupled with a lever branch claw 14 by an inversion spring 18. While a path change claw 2 is switched by a solenoid 11 directly from a reception position to a feed-out position, a reversing driven roller 8 is switched from a separated position to a form clamping position through the inversion spring 18. Therefore, a form jam due to the switching of the reversing driven roller 8 before the path change claw 2 can securely be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is directed to a pair of reversing conveying rollers provided inside a reversing path and capable of contacting and separating one roller from the other roller, and at the entrance of the reversing path to guide a sheet to a duplex unit. An image that has a path changing pawl that can be switched to a position, in which the sheet fed into the reversing path is conveyed in reverse by contacting the reversing roller pair, and guided by the path changing pawl with the rear end side as the front end to the duplex unit. The present invention relates to a sheet reversing mechanism of a forming device.

[0002]

2. Description of the Related Art A paper reversing mechanism of the above type is well known and is attached to an image forming apparatus having a double-sided function such as a copying machine and a printer. This type of reversing mechanism, as shown in FIG. 7, is a lever branch pawl 35 that rotates the passage changing pawl 33.
And a reversing lever 36 for rotating one of the reversing rollers, that is, the reversing passive roller 34 so as to contact a reversing driving roller (not shown), are connected to the same link lever 32 connected to the solenoid 31.

[0003]

However, when the lever branch pawl 35 and the reversing lever 36 are actuated by the same link lever 32, the passage changing pawl is caused by the positional tolerance between the lever branch pawl 35 and the reversing lever 36, the assembly tolerance and the like. 33
Before the paper comes to the delivery position, the reverse passive roller 34 presses the reverse drive roller to reversely convey the paper, and the paper is applied to the conveyance drive roller (not shown) to cause a paper folding jam. ..

SUMMARY OF THE INVENTION It is an object of the present invention to solve the conventional problems described above and to provide a reversing mechanism of an image forming apparatus capable of reliably preventing jamming of the paper when the paper is reversed.

[0005]

The structure of the present invention for achieving the above object is as follows.

(1) A pair of reversing conveyance rollers provided inside the reversing path and one roller of which can contact and separate from the other roller, and a receiving position which is provided at the entrance of the reversing path and guides the sheet into the reversing path. It has a path changing pawl that can be switched between the feeding position leading to the unit and the sheet fed into the reversing path, the pair of reversing rollers come into contact and convey the sheet in reverse, and the path changing claw guides the rear end side. In the sheet reversing mechanism of the image forming apparatus that conveys the sheet to the duplex unit as the leading edge, one of the reversing rollers comes into contact with the other roller to reversely convey the sheet and the path changing claw is switched to the delivery position for guiding the sheet to the duplex unit. The paper reversing mechanism is characterized by delaying the timing so that the reversing roller operates after the operation of the path changing claws.

(2) A drive source for operating the passage changing pawl and the reversing roller is connected to the passage changing pawl, and the drive of the driving source is transmitted to the reversing roller via a spring, thereby The sheet reversing mechanism according to (1), wherein the timing is delayed so that the reversing roller operates after the operation.

(3) A drive source is individually connected to the passage changing pawl and the reversing roller, and a control unit for giving an operation signal to these driving sources delays the timing so that the reversing roller operates after the passage changing pawl operates. The sheet reversing mechanism described in (1) above is characterized in that an actuation signal for causing the sheet to be crushed is given.

[0009]

According to the above construction, the passage changing pawl is operated in contrast to the operation of one roller of the reversing roller contacting the other roller for reversing and conveying and the operation of switching the sheet of the path changing pawl to the feeding position for guiding the sheet to the duplex unit. Since the timing is delayed so that the reversing roller operates later, one roller of the reversing roller does not come into contact with the other roller prior to the operation of the path changing claw, and it is possible to prevent the paper jam in the reversing path.

[0010]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an explanatory view showing an embodiment of a reversing mechanism according to the present invention. In FIG. 1, reference numeral 1 is a reversing mechanism, and the reversing mechanism 1 is arranged between a fixing device (not shown) and a duplex unit. The reversing mechanism 1 is provided with a reversing path 4 formed by a path changing claw 2 and a guide plate 3, and a sheet sent from the direction of arrow A through the upper flow path 10A after finishing fixing on the upper part of the reversing path 4 ( A conveyance drive roller 5 for conveying (not shown) into the reverse path 4 and a first roller 6 are provided. Reversing rollers 7 and 8 for reversing a sheet (not shown) fed into the reversing path 4 in the reverse direction, that is, the arrow B direction are provided at the lower part of the reversing path 4, and the reversed sheet is an upper part of the reversing path 4. The sheet is conveyed in the direction of arrow C through the lower flow path 10B by the conveyance driving roller 5 and the second roller 9 provided in the above and is sent to the duplex unit.

The passage changing pawl 2 is fixed to a lever branch pawl 14 mounted so as to be rotatable about a shaft 13, and the lever branch pawl 14 is connected to a link lever 12 connected to a solenoid 11 as a drive source. Has been done. in this case,
The lever branch claw 14 has a long hole 15A formed therein.
5A is fitted with the pin 15B fixed to the link lever 12, so that the lever branch claw 14 and the link lever 1
2 and are connected. The passage changing pawl 2 is swung by the solenoid 11 between the receiving position shown in FIGS. 1 and 2 and the feeding position shown in FIG.

The reversing rollers 7 and 8 are composed of a position-reversing reversing driving roller 7 and a left reversing passive roller 8 which are provided on the right side in the figure, and the reversing passive roller 8 is rotatable about a shaft 16. It is supported by the mounted reversing lever 17. The reversing lever 17 is connected to the lever branch claw 14 by the reversing spring 18.
The reference numeral 19 designates the reversing passive roller 8 and the reversing driving roller 7.
Is a spring for holding at a separated position away from.

The operation mode of the reversing mechanism 1 thus constructed is as follows.
It is as follows. When the double-sided command is issued, the paper is conveyed from the direction of arrow A through the upper flow path 10A, and the paper is sandwiched between the conveyance drive roller 5 and the first roller 6 and the reverse path 4 is conveyed.
Get inside. At this time, the passage changing pawl 2 is connected to the solenoid 1
Since 1 is off, it is held at the receiving position shown in FIGS. 1 and 2, and the reversing passive roller 8 is also held at the separated position. Then, the trailing edge of the paper is the conveyance drive roller 5
When the first roller 6 is disengaged, the solenoid 11 is turned on, and as shown in FIG. 3, the lever branch claw 14 connected to the link lever 12 is rotated clockwise about the shaft 13 to move to the delivery position. To do. After this movement, the reversing lever 17, which is connected to the lever branching pawl 14 by the reversing spring 18, pivots clockwise about the shaft 16, and the paper is nipped by the reversing drive roller 7 and the reversing passive roller 8.

The sheet sandwiched between the reversing drive roller 7 and the reversing passive roller 8 is reversed so that the rear end becomes the leading end, and is guided by the path changing claw 2 toward the nip between the conveying drive roller 5 and the second roller 9. It is conveyed in the direction of arrow B. When sandwiched between the transport drive roller 5 and the second roller 9, the lower flow path 10
It is sent through B in the direction of arrow C.

Thus, the sheet is reversed by the reversing mechanism 1 and conveyed to the double-sided unit. In this embodiment, the path changing claw 2 is directly switched from the receiving position to the sending position by the solenoid 11, whereas the reversing passive mechanism is used. The roller 8 is switched from the separated position to the paper holding position via the reversing spring 18. Therefore, the passage switching claw 2 and the reverse passive roller 8 are switched at different timings,
Since the drive is transmitted to the reversing passive roller 8 after the passage changing pawl 2 is switched, it is possible to reliably prevent a paper jam due to the reversing passive roller 8 being switched before the passage changing pawl 2.

FIG. 4 is an explanatory view showing another embodiment of the present invention. In this embodiment, the path changing claw 2 and the reversing passive roller 8 are provided.
Are connected to solenoids 11 and 20 as separate drive sources. As shown in FIG. 5, the solenoids 11 and 20 are controlled by the control unit 21 according to the flow shown in FIG. 6, for example. That is, when the trailing edge of the sheet passes through the transport driving roller 5 and the first roller 6 and the reversal signal is transmitted, the solenoid 11 is activated and the passage changing pawl 2 is switched from the receiving position to the sending position by the solenoid 11. Then, after waiting for 0.5 seconds, the solenoid 20 is actuated and the reversing passive roller 8 is switched from the separated position to the sheet holding position. The reversing mechanism 1 thus configured can also achieve the same effect as that of the above-described embodiment.

[0017]

According to the structure of the first aspect of the present invention, one of the reversing rollers comes into contact with the other roller to reversely convey the sheet and the operation of switching the sheet of the path changing claw to the position for guiding the sheet to the duplex unit. Since the timing is delayed so that the reversing roller operates after the passage changing pawl operates, one of the reversing rollers does not come into contact with the other roller before the passage changing pawl operates, so that the paper in the reversing path does not move. Jam can be reliably prevented.

According to the second aspect of the invention, the timing can be delayed so that the reversing roller is activated after the passage changing pawl is activated with a simple configuration in which the reversing spring is provided.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a reversing mechanism according to the present invention.

FIG. 2 is an explanatory diagram showing a mode of receiving a sheet.

FIG. 3 is an explanatory view showing a mode at the time of feeding the paper.

FIG. 4 is an explanatory view showing another embodiment of the present invention.

FIG. 5 is a control block diagram of FIG.

FIG. 6 is a control flow chart thereof.

FIG. 7 is an explanatory view showing a part of a conventional reversing mechanism.

[Explanation of symbols]

 1 Reversing mechanism 2 Passage changing claw 4 Reversing path 7,8 Reversing roller 11,20 Solenoid 18 Reversing spring

Claims (3)

[Claims] 1. A double-sided unit and a pair of reversing conveyance rollers provided inside the reversing path and capable of contacting and separating one roller from the other roller, and a receiving position provided at the entrance of the reversing path for guiding a sheet into the reversing path. Has a path changing claw that can be switched between a feeding position that guides the sheet and a sheet that has been fed into the reversing path, the pair of reversing rollers make contact and convey the sheet in reverse, and the path changing claw guides the sheet to the rear end side. In the sheet reversing mechanism of the image forming apparatus that conveys the sheet to the double-sided unit as one, the one of the reversing rollers comes into contact with the other roller to reversely convey the sheet, and the operation of switching the sheet of the path changing claw to the delivery position for guiding the sheet to the two-sided unit On the other hand, a sheet reversing mechanism that delays the timing so that the reversing roller operates after the passage changing pawl operates. 2. The passage changing pawl is connected to a drive source for operating the passage changing pawl and the reversing roller, and the drive of the driving source is transmitted to the reversing roller via a spring to operate the passage changing pawl. The sheet reversing mechanism according to claim 1, wherein the timing is delayed so that the reversing roller is activated later. 3. A drive source is individually connected to the path changing pawl and the reversing roller, and a control unit for applying an operation signal to these driving sources delays the timing so that the reversing roller operates after the passage changing pawl is operated. The sheet reversing mechanism according to claim 1, wherein an operation signal is given.