JP2719204B2 - Switch device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switchback device for switching a sheet conveying direction from one direction to a reverse direction in an image forming apparatus such as a copying machine, a printer, and a facsimile.

[Conventional technology]

2. Description of the Related Art An image forming apparatus such as a copying machine having a switchback device for temporarily stopping a sheet on which image formation on the front side has been completed in a sheet conveyance path, and then switching the sheet to a refeeding path to form an image on the backside. There is.

FIG. 8 shows an example of such a conventional switchback device. As shown in FIG. 8A, a sheet P is shown by a pair of carry-in rollers 21 and 22 which rotate in the directions indicated by arrows. After being conveyed to the left by the rotation of the pair of reversing rollers 24 and 25 in the direction of the arrow, to the position shown in FIG.
The rotation of the pair of reversing rollers 24 and 25 is stopped, and the switching claw 26 is turned clockwise to switch the sheet conveyance path.

In this state, as shown in FIG.
When the rollers 4 and 25 rotate in the reverse direction, the sheet P is returned to the right, and is conveyed to a re-feeding path (not shown) by the rotation of the pair of discharge rollers 22 and 23 in the direction indicated by the arrow, thereby completing the switchback operation.

FIG. 9 shows a switchback device disclosed in U.S. Pat. No. 3,944,212, in which a sheet P sent downward by the rotation of the carry-in roller pair 31 and 32 in the direction of the arrow is a non-reversing roller pair. Clearance between perfect roller 34 and driven roller 35
It is introduced into the switchback part 37 through the insertion of the reference numeral 36.

When the paper P passes through the nip portion of the pair of carry-in rollers 31 and 32 and is introduced into the switchback portion 37, the detecting means 38 and 39 detect this, and the non-circular roller 34 makes one rotation in the direction indicated by the arrow. The sheet P is nipped between the driven rollers 35 and sent upward, and is conveyed by the pair of discharge rollers 32 and 33, thereby completing the switchback operation.

According to this device, the leading paper is fed to the discharge roller pair 32, 33.
After the sheet is nipped, a gap 36 is formed between the non-circular roller 34 and the driven roller 35.
Even if the paper has not completely escaped, the leading edge of the next paper
36 can be introduced, and the paper reversal cycle can be shortened.

[Problems to be solved by the invention]

However, such conventional switch devices have the following problems.

That is, in the former case, since the pair of reversing rollers 24 and 25 are always in a pressure contact state, the next sheet cannot be carried in unless the switch of the preceding sheet is completed, and the productivity in the switch section is low. It cannot be applied to high-speed aircraft.

In the latter case, after the paper is introduced into the switchback portion 37 and is separated from the nip portion of the carry-in roller pair 31, 32, the paper is restrained by any roller until the non-circular roller 34 starts. Since the sheet is left in a free state, there is a possibility that the sheet that is reversely fed by the pair of reversing rollers 34 and 35 may be skewed.

The present invention has been made in view of the above points,
An object of the present invention is to provide a switch device which can continuously switch sheets at short intervals and does not cause skewing of sheets.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, a continuous feed sheet fed by a pair of carry-in rollers in a state of being partially overlapped by a predetermined amount in the transport direction is moved forward by a pair of reversing rollers pressed against a sheet transport path. In the switchback device which sequentially feeds back one sheet at a time and feeds the sheet by a pair of conveying rollers, the distance between the pair of reversing rollers, the pair of carrying-in rollers and the pair of carrying-out rollers is determined by the length of the minimum usable sheet in the conveying direction. In addition to the following, the feed roller on the side pressed against the next sheet of the reverse roller pair is rotated in the loading direction, and the reverse roller on the side pressed against the preceding sheet is rotationally driven in the opposite direction via a torque limiter. The torque limiter does not transmit the driving force when the number of sheets sandwiched by the nip portion of the pair of reversing rollers is one or less.
In the case of two or more sheets, the information is transmitted.

(Operation)

With the above configuration, the torque limiter does not transmit the driving force from the time when there is no paper at the nip portion of the reversing roller pair to the time when only the first paper is nipped by the nip portion. Feeds the paper by rotating it with a feed roller rotating in the carry-in direction.

At the end of the feeding of the first sheet, the next sheet, which is sent over the trailing end, is sent to the nip of the pair of reversing rollers, so that the nip holds two sheets of paper.

As a result, the torque limiter is in a state capable of transmitting the driving force, the reverse roller rotates in the return direction, and the leading sheet is fed back in the opposite direction to the discharge roller against the frictional force with the next sheet. A switchback is performed.

At this time, the next sheet is still fed in the feeding direction, so that the switchback cycle can be advanced.

Further, since the distance between the pair of reversing rollers, the pair of carry-in rollers and the pair of carry-out rollers is set to be equal to or less than the minimum length in the feed direction of the paper, the paper is always restrained by any one of the pair of rollers. Therefore, there is no possibility that the sheet is skewed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 7 of the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 to 5 are explanatory views showing different operation states thereof, and FIG. 6 is a sectional view of a principal part showing an example of the torque limiter. .

In this embodiment, as shown in FIG.
15, a pair of reversing rollers 5, 6 for retrieving the paper P sent to the retrieving path 15 into the switchback section 16 and returning the conveyed paper in the reverse direction, and a pair of reversing rollers 5, 5. The transport roller pair 3 and 4 for feeding out the paper fed back by 6 and the paper backflow prevention plate 7 made of an elastic body such as a mylar or a leaf spring provided at the intersection of the carry-in path 15 and the carry-out path 17.

The pair of reversing rollers 5 and 6 are composed of a feed roller 5 and a reverse roller 6 pressed against the feed roller 5 by a pressure spring 8 with a sheet conveying path interposed therebetween. The feed roller 5 has the same peripheral speed as the feed rollers 1 and 2. Rotate in the direction to feed paper.

On the other hand, the reverse roller 6 is fixed to a sleeve 10 rotatably mounted on a shaft 9 as shown in an example in FIG. 6, and this sleeve 10 is fixed to the shaft 9 via a pin 11. A spring clutch 13 acting as a torque limiter is engaged between the flange portion 12 and applies a reverse torque to the reverse roller 6 in a direction in which the sheet is fed back when the shaft 9 rotates counterclockwise in FIG.

The torque limiter constituted by the spring clutch 13 includes a reverse roller 6 and a feed roller 5.
When there is no sheet between the rollers and when only one sheet is nipped between the nip portions of both rollers, the driving force is not transmitted, and the reverse roller 6 rotates with the feed roller 5 so that two or more sheets are When the sheet is nipped, the torque overcomes the frictional force between the sheets to rotate the reverse roller 6 in the feed-back direction at the same speed as the peripheral speed of the pair of discharge rollers 3 and 4.

Further, the distance L ₂ between the end which projects into the introduction passage 15 of the paper check plates 7 and Nitsupu portion of the pair of reverse rollers 5,6, and larger than the paper overlapping amount L ₁ (see FIG. 7) Paper Backflow into the carry-in path 15 is prevented.

Next, the operation of the embodiment having the above configuration will be described in the second.
Prior to the description of the embodiment, a method of continuously feeding sheets used in the present invention will be briefly described with reference to FIGS.

The sheets P ₁ , P ₂ , P ₃ ... Of the length L in the transport direction are connected in a state in which the leading end of the next sheet overlaps the back of the trailing end of the leading sheet by the length L _1. Sent.

Thus the first sheet P ₁ supplied with the second sheet P ₂ is fed into the introduction passage 15 by the rotation of arrow direction of the carry roller pair 1,2 as shown in Figure 2 is, the sheet P ₁ is sent to Nitsupu portion of the pair of reverse rollers 5,6 while deforming against a paper check plates 7 on its resilient force by the strength of its own stiffness.

Prior to this, the reversing rollers 5 and 6 are
Since There are Kaitsu taken to feedroll 5, when the leading end of the sheet P ₁ reaches the Nitsupu portion of the pair of reverse rollers 5,6, the leading end of the sheet P ₁ as shown in Figure 3 is sandwiched at its Nitsupu portion Suitsuchibatsuku Sent to section 16.

Next, as shown in FIG. 4, when the overlapping portion of the sheets P ₁ and P ₂ is sandwiched between the nip portions of the pair of reversing rollers 5 and 6, the torque limiter can transmit the driving force, and the rotation of the shaft 9 is performed. There is transmitted to the reverse roller 6, the sheet P ₁ is sent back to the right in FIG.

At this time, the paper P ₂ is fed by the feed roller 5 and the transport roller pair.
Since the sheets P ₁ and P ₂ are sent to the switchback section 16 by the lines 1 and 2, the sheets P ₁ and P ₂ are conveyed by the nip section of the pair of reversing rollers 5 and 6.

Figure 5 is backhaul sent back the sheet P ₁ is the carry-out roller pair 3,4, the sheet P ₂ is the progressive to Suitsuchibatsuku portion 16, are simultaneously conveyed sheet P ₃ is the introduction passage 15 state Is shown.

In this way, the sheets P ₁ , P ₂ , P _3, ... Are switched back one by one sequentially from the leading sheet and sent back.

In the above embodiment, the peripheral speed of the pair of unloading rollers 3 and 4 in the loading direction is adjusted by the pair of unloading rollers 3 and 4 and the reverse roller 6.
Of was equal to the reverse feed direction of the peripheral speed, when requiring sheet interval to the paper to be sent back by the discharging roller pair 3 and 4, the peripheral speed v ₂ of the out direction of the unloading rollers 3,4 carrying roller pair 1, 2 and may be greater than the loading direction of the peripheral speed v ₁ of the pair of reverse rollers 5,6, the sheet interval can be freely changed Te cowpea to changing the ratio of v ₂ / v ₁ .

Further, the torque limiter for intermittently transmitting the rotational force of the shaft 9 to the reverse roller 6 can obtain the same effect even if it is based on frictional force or electromagnetic force, not depending on the spring clutch.

〔The invention's effect〕

As described above, according to the present invention, the reverse roller of the pair of reversing rollers can be driven to rotate in the paper feed-back direction via the torque limiter. Feeding is performed at the nip portion of the pair of reversing rollers at the same time, so that the cycle of the switchback can be greatly reduced, and the productivity can be improved.

In addition, since the distance between the pair of reversing rollers and the pair of carry-in and carry-out rollers is set to be equal to or less than the minimum length of the sheet, the sheet to be conveyed is always restricted by one of the pair of rollers, and the skew of the switched-back sheet is always suppressed. There is no danger.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIGS. 2 to 5 are explanatory views showing different operation states thereof, FIG. 6 is a sectional view of a main part showing an example of the torque limiter, FIG. 7 is an explanatory view showing a continuous paper feeding method used in the present invention, FIGS. 8 (a), (b) and (c) are explanatory views showing different operation states of a conventional switch device, and FIG. FIG. 9 is a configuration diagram showing a different example of the conventional switch device. 1,2 ... Loading roller pair, 3,4 ... Unloading roller pair 5 ... Feed roller (reversing roller pair) 6 ... Reverse roller (reversing roller pair) 7 ... Paper backflow prevention plate, 8 ... Pressure spring 9: Reverse roller shaft 13: Spring clutch, 15: Loading path 16: Switch back, 17: Loading path

Claims (1)

(57) [Claims] A continuous feed sheet fed by a pair of carry-in rollers in a state where a part thereof is overlapped by a predetermined amount in a conveying direction is sequentially transferred one sheet from a leading sheet by a pair of reversing rollers pressed against a sheet conveying path. In a switchback device for feeding back each time and sending it out by a carry-out roller pair, the interval between the reversing roller pair, the carry-in roller pair and the carry-out roller pair is set to be equal to or less than the minimum usable length of the sheet in the carrying direction, and The feed roller on the side that comes into pressure contact with the next sheet of the reversing roller pair is rotated in the loading direction, and the reverse roller on the side that comes into contact with the preceding sheet can be driven to rotate in the opposite direction via a torque limiter. When no more than one sheet is sandwiched between the nip portions of the reversing roller pair, no driving force is transmitted and
A switch-back device characterized in that when the number of sheets is more than one, it is transmitted.