JPH08333056A - Double-face device - Google Patents

Abstract

PURPOSE: To surely feed the paper to a double-face tray over a long period and refeed the paper from it without generating a jam. CONSTITUTION: When a feed roller 13 is rotated in the first direction of an arrow A to feed the paper P to a double-face tray 12, a separation roller 42 is located at the first position shown by a solid line. When the feed roller 1 3 is reversely rotated in the second direction to deliver the paper P in the double-face tray 12, the separation roller 42 is moved to the second position shown by a virtual line by the frictional force with the feed roller 13. The left end of the separation roller 42 is set to the left side across the vertical wall 54a of a guide plate 54 at the first position. The rear end of the paper P can be surely fed into the double-face tray 12. The separation roller 42 is moved to the second position when the paper P is refed, and the separation roller 42 does not hinder the paper refeeding action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
The present invention relates to a double-sided device provided in an image forming apparatus such as a facsimile and used when forming images on both sides of a sheet.

[0002]

2. Description of the Related Art A double-sided device used to form an image on both sides of such a sheet is, for example, a double-sided tray for storing the sheet on which an image is formed on one side, and a sheet for feeding the sheet into the double-sided tray. There is one including a feed roller rotatable in one direction and a second direction for feeding a sheet from the double-sided tray, and a separation roller rotatable in pressure contact with the feed roller.

The feed roller and the separation roller are formed of, for example, a rubber elastic body, and when the sheets on which an image is formed on one side are stored in a double-sided tray, the feed roller is normally rotated in the first direction. Function as a transport roller, and the separation roller rotates following the feed roller to function as a transport roller. When the paper stored in the double-sided tray is re-fed, the feed roller reversely rotates in the second direction to function as a calling roller and a paper feeding roller, and the separation roller is stopped. And play the role of the original separation roller.

As described above, in the double-sided device in which the feed roller has both the stacking function and the sheet re-feeding function, the tip end of the elastic guide (elastic piece) made of a polyester film or the like is constantly applied to the outer peripheral surface of the feed roller. Some of them are brought into contact with each other to improve the transportability and the sheet feeding property of the sheet by the function of the elastic guide (for example, JP-A-63-15).
4540, JP-A-63-154541).

Such an elastic guide is shown in FIGS. 11 and 1.
Like the elastic guide 4 shown in FIG. 2, the tip portion 4a thereof is always in contact with the feed roller 3, and the tip portion 4a changes its direction from side to side depending on the rotation direction of the feed roller 3.
As a result, the transportability of the paper is improved.

That is, when the sheets 4 are stacked with the front end 4a of the elastic guide 4 facing left as shown by the phantom line in FIG. 12, the rear end of the paper P fed into the double-sided tray 2 is set to the front end of the elastic guide 4. It is pressed against the outer peripheral surface of the feed roller 3 by 4a so that the rear end of the sheet P is not caught by the guide plate 7 by the conveying force of the feed roller 3 and falls onto the bottom plate 5 of the double-sided tray 2. Further, at the time of re-feeding in which the leading end portion 4a faces the right side as shown by the solid line in FIG. 12, the elastic guide 4 contacts the sheet P fed from the double-sided tray 2 with the contact portion between the feed roller 3 and the separation roller 6 ( It works to guide to the nip).

[0007]

However, when the feed roller 3 is rotated in the direction of arrow B and then rotated in the direction of arrow A as shown in FIG. The tip portion 4a changes its direction from the indicated position to the position indicated by the solid line while being largely bent as shown in the drawing. This elastic guide 4 changes its direction while bending,
The same occurs not only when the feed roller 3 changes its rotation direction in the arrow A direction, but also when it changes its rotation direction in the opposite arrow B direction (from the position where the tip end portion 4a is indicated by the solid line to the position indicated by the imaginary line). Change).

The change of the direction of the elastic guide 4 while causing the flexure is repeated every time the stack operation is changed to the sheet re-feeding operation or the opposite operation is changed during double-sided image formation. 14 (a) in FIG.
As shown in FIG. 14, a crack Cr may be generated at the tip 4a of the elastic guide 4, and the portion may be cut as shown in FIG. 14 (b). When the tip portion 4a of the elastic guide 4 is cut in this manner, the tip portion 4a is cut off as shown in FIG.
Since it does not come into contact with the outer peripheral surface of the feed roller 3 shown in FIG. 2, the elastic guide 4 cannot guide the paper P or perform the function of pressing the paper P against the outer peripheral surface of the feed roller 3, so that the paper is not conveyed properly. Occurs.

The present invention has been made in view of the above problems, and even in a double-sided device having a feed roller that rotates in both forward and reverse directions, a sheet having an image formed on one side thereof is transferred to a double-sided tray for a long time. It is an object of the present invention to reliably feed the sheets of paper over the entire length of the sheet and to re-feed the sheets of paper stored in the double-sided tray without causing a jam.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is a double-sided device as described above, wherein the separating roller is at the first position when the feed roller rotates in the first direction. When the feed roller rotates in the second direction, the feed roller is movably provided so as to come into contact with the feed roller at the second position moved away from the double-sided tray from the first position. Also,
Due to the frictional force generated when the separation roller comes into contact with the feed roller, the first roller is rotated according to the rotation direction of the feed roller.
It is advisable to move to the position and the second position. Further, the separating roller may be held by a swing member.

[0011]

According to the double-sided device configured as described above, when the feed roller rotates in the first direction for feeding the paper into the double-sided tray, the separation roller is in the first position, and the feed roller is moved from the double-sided tray. When the paper is rotated in the second direction for feeding the paper, the separation rollers come into contact with the feed rollers at the second position, which is moved in the direction away from the double-sided tray from the first position. Therefore, by setting the first position to a position where the separation roller feeds the double-sided tray to the double-sided tray without hooking the rear end of the sheet to the guide plate or the like, it is possible to reliably store the sheet on which the image is formed on one side. Can be sent to a double-sided tray.

Further, when the feed roller rotates in the second direction, the separation roller comes into contact with the feed roller at the second position moved away from the first position in the direction away from the double-sided tray. When the feed roller re-feeds the sheet, the separation roller does not interfere with the re-feeding operation, so that reliable re-feeding can be performed without causing a jam.

Then, the separation roller is moved to the first position and the second position according to the rotation direction of the feed roller by the frictional force at the time of contact with the feed roller. The separating roller automatically changes its position according to the rotation of the feed roller, even if the moving mechanism using a drive source from the outside does not forcibly move it to the first and second positions. Therefore, the number of parts can be reduced and the configuration can be simplified. Further, if the separating roller is held by the swinging member, the separating roller moves to the first and second positions by swinging about the fulcrum of the swinging member, so that the separating roller and the separating roller are moved. It is possible to minimize the space required for moving the holding member.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an embodiment of a double-sided device according to the present invention together with a part of an image forming apparatus. This double-sided device 1 has a sheet P having an image formed on one side.
A double-sided tray 12 for storing paper, a first direction indicated by an arrow A for feeding the paper P into the double-sided tray 12, and a second direction opposite to the arrow A for feeding the paper P out of the double-sided tray 12. It comprises a possible feed roller 13 and a separating roller 42 in contact with the feed roller 13.

When the feed roller 13 rotates in the first direction, the separating roller 42 is at the first position shown by the solid line in FIG. 1, and when the feed roller 13 rotates in the second direction, the separation roller 42 is in the first position. The second position, which is moved from the first position in the direction away from the double-sided tray 12 (rightward in FIG. 1) and which is shown by an imaginary line in the figure, is movably provided so as to contact the feed roller 13.

The double-sided tray 12 has a movable bottom plate 15 on which a sheet P having an image formed on one side is stacked. The bottom plate 15 is placed on the bottom plate 15 by the bottom plate moving means 11. The P is brought into contact with the feed roller 13 and is rotated about a fulcrum 21 to a raised position shown by an imaginary line in FIG.

The double-sided device 1 also includes a double-sided tray 12
The paper P fed by the feed roller 13 and the separation roller 42 that is pressed against the feed roller 13 is rotated toward and away from each other in the front and back directions (jogging operation) in FIG. A pair of side fences (not shown) that align their positions, and a double-sided tray 1
Also provided is an end fence 43 that can reciprocate in the left-right direction in FIG. 1 for aligning the position of the front end portion (which becomes the rear end at the time of re-feeding) of the paper P fed onto the sheet 2.

As shown in FIG. 2, the feed roller 13 is attached to the feed roller shaft 16 so as to come into contact with the vicinity of the transportation center of the paper P to be fed with a predetermined width. When feeding the paper P from the double-sided tray 12 of FIG. 1, the double-sided device 1 raises the front end side of the bottom plate 15 by the bottom plate moving means 11 to bring the paper P on the double-sided tray 12 into contact with the feed roller 13.

FIG. 3 shows the bottom plate 15 and the feed roller 13 thereof.
It is a perspective view which shows the mechanism which operates. This mechanism drives the feed roller 13 and the bottom plate moving means 11 by a motor 22 which is the same drive source. The bottom plate moving means 11
Transmits the rotational force from the motor 22 to the lever holding shaft 39 via the speed reduction mechanism 23, and rotates the pressure lever 37 fixed thereto to move the bottom plate 15 around the fulcrum 21 (FIG. 1). To rotate.

When the motor 22 is rotated to rotate the feed roller 13 in the second direction indicated by the arrow B, the bottom plate moving means 11 is operated via the reduction mechanism 23, and the bottom plate 15 is moved.
The deceleration mechanism 23 moves the feed roller 13 to the raised position (the position changes depending on the number of sheets of paper loaded on the bottom plate 15) shown in phantom in FIG. 1 with a delay from the timing when the feed roller 13 starts to rotate. The reduction mechanism 23 is composed of a large number of gears arranged in a train of wheels as shown in FIG. 3, and the drive gear 24 fixed to the rotation shaft of the motor 22 has a large diameter portion of the first idle gear 25. The second idle gear 2 is engaged with the small diameter portion of the first idle gear 25.
The large diameter part of 6 is meshed.

Further, a third idle gear 27 meshes with the small diameter portion of the second idle gear 26, and an input gear 28 meshes with the third idle gear 27. A gear 31 for sequentially transmitting the rotational force from the motor 22 to another drive system is meshed with the input gear 28, and gears 32 and 33 are sequentially meshed with it.

A cam 29 is attached to the input gear 28 via a clutch 30 that idles when a predetermined load or more is applied, and a pin 34 is attached to the cam 29 at a position eccentric from the rotation center. , One end of a pressure spring 35 is attached to the pin 34. Then, the other end of the pressure spring 35 is attached to a pressure arm 36 fixed to one end of a lever holding shaft 39 rotatably held by a fixing portion of the double-sided device. The lever holding shaft 3
The numeral 9 fixes one end of a pressure lever 37 for rotating the bottom plate 15 at a position substantially corresponding to the center of paper conveyance.

On the other hand, a roller driving gear 38 meshes with the small diameter portion of the second idle gear 26, and the roller driving gear 38 is one end of the feed roller shaft 16 rotatably held by the fixed portion of the double-sided device 1. And the feed roller 13 is fixed to the feed roller shaft 16.

The image forming apparatus having the double-sided device 1 shown in FIG. 1 configured as described above is not shown when the double-sided image forming mode for forming images on both sides of a sheet is selected and the image forming operation is started. A toner image is formed on one surface of the paper P by the image forming unit, and the toner image is conveyed to the fixing unit 17 in an unfixed state, and the toner image is fixed there.

The sheet P is conveyed to the reverse conveyance path 19 by the branching claw 18 which is switched to the position shown by the phantom line in FIG. It is sent onto the double-sided tray 12 by the conveying force of the separation roller 13 and the separation roller 42. The paper P
Immediately after being fed onto the double-sided tray 12, the front, rear, left, and right positions are aligned by side fences and end fences 43 (not shown). Then, in the case of forming a double-sided image on a plurality of sheets, this series of operations is repeated.

When all of the designated number of sheets are stacked on the double-sided tray 12 in this way, the bottom plate 15 feeds the paper P on the double-sided tray 12 in the direction opposite to the arrow A in FIG. The roller 13 is rotated to an ascending position indicated by an imaginary line. As a result, the sheets P are sequentially re-fed from the topmost sheet. Note that this re-feeding is performed while the paper P on the double-sided tray 12 is aligned in the front, rear, left, and right positions by the pair of side fences and the end fence 43, so that it is not skewed or is not fed. .

The rotation operation of the bottom plate 15 and the rotation drive of the feed roller 13 are performed by the same motor 22 as described in FIG. 3, and the rotation of the bottom plate 15 is indicated by an imaginary line in FIG. As described above, the reaching of the raised position is delayed from the timing when the feed roller 13 rotates in the sheet re-feeding direction (second direction) shown by the arrow B in FIG. 3 due to the action of the speed reduction mechanism 23.

That is, the double-sided device 1 according to this embodiment.
Means that when the motor 22 rotates in the direction of arrow C in FIG. 3, the feed roller 13 rotates in the direction opposite to arrow B,
When all of the designated number of sheets have been stacked on the double-sided tray 12, this motor 22 rotates in the direction opposite to the arrow C to start the re-feeding operation. As a result, the drive gear 24 rotates clockwise in FIG. 3, and the first idle gear 25 meshing with the drive gear 24 rotates counterclockwise. Further, the rotational force is transmitted to the roller drive gear 38 via the second idle gear 26, and the feed roller 13 rotates in the direction of arrow B via the feed roller shaft 16 integrated with the roller drive gear 38.

A third idle gear 27 is also meshed with the second idle gear 26, and an input gear 28 having a cam 29 for rotating the bottom plate 15 is meshed with the third idle gear 27. Therefore, the input gear 28 simultaneously rotates in the clockwise direction in FIG.

The rotation speed of the input gear 28 is slower than the rotation speed of the roller drive gear 38 because the speed reduction ratio of the speed reduction mechanism 23 is increased by increasing the number of teeth of the input gear 28. Therefore, the input gear 28 rotates slowly with respect to the rotation of the roller drive gear 38, and the cam 29 rotates in the arrow E direction from the position shown in FIG. 4 at the rotation speed thereof.

Abutment portions 29a and 29b are formed on the outer periphery of the cam 29 at positions of 180 ° out of phase with each other. As shown in FIG. 5, the cam 29 rotates in the direction of arrow E as shown in FIG. When the contact portion 29b contacts the stopper 45, further rotation of the cam 29 is restricted.

After that, the input gear 28 continues to rotate in the clockwise direction in FIG. 3, but the rotation of the input gear 28 idles at the portion of the clutch 30 mounted between the input gear 28 and the cam 29. 29 is stopped. In this way, when the cam 29 rotates to the position shown in FIG. 5, the pin 34 attached to the cam 29 becomes the position farthest from the bottom plate 15, so that the pressure spring 35 moves the pressure arm 36 in the arrow direction. Rotate in the F direction.

Therefore, the lever holding shaft 39 rotates in the same direction, and the pressure lever 37 fixed thereto rotates in the same direction, so that the pressure lever 37 causes the bottom plate 15 to rotate.
Is rotated to the ascending side, and the uppermost sheet stacked on the bottom plate 15 is moved to the ascending position shown by the phantom line in FIG. And
The movement of the bottom plate 15 to the raised position is delayed from the timing when the feed roller 13 starts rotating in the direction opposite to the arrow A in FIG.

When the cam 29 is rotated in the counterclockwise direction from the position shown in FIG. 5 to the position shown in FIG. 4, the pressure lever 37 rotates clockwise in FIG. Since it is biased by a weak spring, it returns to the position shown in the figure by its biasing force, and the bottom plate 15 also returns to the position shown in the figure by its own weight.

By the way, in the double-sided device 1, as described with reference to FIG. 1, the separation roller 42 sends the sheet into the double-sided tray 12 in accordance with the rotation direction of the feed roller 13, and the first position thereof. As described above, it is provided so as to be movable to the second position when the paper is sent from the double-sided tray 12 that has moved from the position 1 in the direction away from the double-sided tray 12.

Therefore, a mechanism for movably holding the separation roller 42 at the first and second positions will be described in detail with reference to FIGS. 6 and 7. The separating roller 42 is rotatably attached to a bracket 51, which is a swinging member, at both ends of a shaft 52 via left and right bearings 53, 53.
The bracket 51 is formed of a metal plate material in which a lower half of the bracket 51 is bent in a U shape in FIG. 6, and fulcrum holes 51a are formed in lower portions of both side surfaces thereof as shown in FIG. are doing.

Further, as shown in FIG. 6, a bracket fixing plate 55 corresponding to the bracket 51 is fixed to the vertical wall 54a of the guide plate 54 of the double-sided tray 12 by spot welding, for example. The bracket fixing plate 55 is U-shaped, and fulcrum shafts 56 and 57 are fixed to the tips of the opposite side surfaces thereof, as shown in FIG.
Then, the fulcrum shafts 56 and 57 are rotatably fitted into the fulcrum holes 51a and 51a of the bracket 51, respectively, and the retaining ring 58 for retaining is fitted into the annular groove formed on the fulcrum shaft 57 side. This prevents the bracket 51 from falling off, and the bracket 51 is rotatably attached to the bracket fixing plate 55.

As shown in FIG. 6, the bracket 51 has elongated holes 51b formed on both side surfaces thereof, and a bearing 53 is movable in each elongated hole 51b only in the G direction shown in FIG. It is inserted so as not to. The bearings 53 on both sides of the bearing 53 are urged upward by compression coil springs 59 in FIG. As shown in FIG. 7, the separation roller 42 is formed by attaching a separation member 61 having a large friction coefficient, for example, made of rubber or the like, to the center of a shaft 52 via a hub 48, and both ends of the shaft 52 are bearings 53. , 53 are rotatably supported, and both ends thereof are retaining rings 62,
A retaining process is performed by 62.

The separating roller 42 is allowed to rotate only in the J direction shown by the arrow in FIG. 6 by the one-way rotating clutch 60 mounted between the shaft 52 and the hub 48, and rotates in the opposite direction. It is supposed not to be done. The rotation position of the bracket 51 that rotatably holds the separation roller 42 is restricted by the first stopper 63 and the second stopper 64.

That is, the separation roller 42 held by the bracket 51 is brought into contact with the first stopper 63 according to the rotation direction of the feed roller 13 by the frictional force caused by the contact with the feed roller 13, as shown in FIG. It moves to a first position shown by a virtual line and a second position shown by a solid line in contact with the second stopper 64. And the first
Is located at a position a on the outermost side of the separation roller 42, which is located on the leftmost side in the figure, protruding a distance L to the left in the figure from the vertical wall 54a of the guide plate 54.

Further, the second position is such that the portion b located on the leftmost side of the outer circumference of the separation roller 42 in FIG.
In the second position, the separating roller 42 comes into contact with the feed roller 13 with a predetermined pressing force suitable for separating the sheet from the vertical wall 54a. The distance L at the first position is appropriately determined for each model in consideration of stackability of sheets stacked on the double-sided tray 12.

By the way, in a conventional double-sided device in which a feed roller rotates in both forward and reverse directions, the tip end of an elastic guide made of polyester film or the like is constantly brought into contact with the outer peripheral surface of the feed roller to feed it to a double-sided tray. It has been described above that there is one that is designed to improve the transportability of the sheets to be stored and to improve the sheet feeding property when the sheets stacked in the double-sided tray are re-fed.

However, such an elastic guide is
Each time the direction of rotation of the feed roller changes, the tip portion greatly bends and the direction of the tip portion changes, so that the bending operation is repeatedly performed, so that
As described in (b), the tip portion 4a of the elastic guide 4 was easily cut early. As a result, the tip end 4a of the elastic guide 4 does not come into contact with the outer peripheral surface of the feed roller,
Since the elastic guide 4 cannot serve the function of guiding the paper or pressing the paper against the outer peripheral surface of the feed roller, defective conveyance of the paper due to a jam or the like is likely to occur at a relatively early stage.

However, in this embodiment, the separation roller 42 is swingably held by the bracket 51 as described with reference to FIG. Since the sheet can be moved between the position and the second position, it is possible to reliably feed the sheet to the double-sided tray 12 and surely re-feed the sheet stacked on the double-sided tray 12. Therefore,
It is possible to have a good stacking property for a long period of time and to reliably perform re-feeding.

That is, as shown in FIG. 6, when the feed roller 13 rotates in the first direction indicated by the arrow A for feeding the paper P to the double-sided tray 12, the separation roller 42 is brought into contact with the feed roller 13. Due to the frictional force, the bracket 51 swings to the first position where it is in contact with the first stopper 63 and is shown by the phantom line in FIG. At the first position, the portion a on the outermost side of the separation roller 42 located on the leftmost side in the figure is
The guide roller 54 protrudes to the left from the vertical wall 54a in the figure by a distance L, and the separating roller 42 is rotated by the one-way rotating clutch 60 described in FIG. Since it rotates driven by the conveying force,
The separation roller 42 is fed to the double-sided tray 12, and the paper P having an image formed on one side thereof is guided by a guide plate 54 at its rear end.
It can be reliably fed to the double-sided tray 12 without being hooked on.

Further, at the time of re-feeding, the feed roller 13
When rotated in the second direction indicated by the arrow B in FIG. 6, the separation roller 42 is moved by the frictional force with the feed roller 13 to cause the first roller
It moves from the position of 2 to the direction away from the double-sided tray 12 and swings to the second position shown by the solid line in FIG. Therefore,
As shown in phantom in FIG. 1, the double-sided tray 12
Even when the paper P inside the paper P moves up to the position where it comes into contact with the feed roller 13, the paper P is already shown by the phantom line in the rising process.
Since it does not contact the separation roller 42 that has been retracted to the position, it is possible to reliably re-feed without jamming.

When the feed roller 13 rotates in the direction opposite to the arrow A, a rotational force for rotating the feed roller 13 in the clockwise direction in FIG. 1 is applied to the separation roller 42. Since this rotation direction is a direction in which rotation is blocked by the one-way rotation clutch 60 (FIG. 7), the separation roller 42 is stopped and is not rotated by the feed roller 13. Therefore, the paper P re-fed from the double-sided tray 12 by the feed roller 13 can be separated into one sheet by a predetermined separating operation. The re-fed paper P is the guide plate 54.
Is guided to the nip between the feed roller 13 and the separation roller 42.

FIG. 8 is a schematic view showing an embodiment of a double-sided device in which a separating roller can be moved to a first position and a second position by a solenoid. In this double-sided device, a bracket 70, which is oscillatably held by a fulcrum shaft 71 and rotatably holds a separation roller 42 at one end, is provided with a solenoid 72 at the above-described first position indicated by a virtual line in FIG. It can be moved to the second position indicated by.

That is, the movable shaft 72a of the solenoid 72
Is attached to the end of the L-shaped bracket 70 opposite to the separating roller 42 via the spring 73, and the separating roller 42 is unidirectionally rotated at the other end of the bracket 70 in the same manner as the embodiment described in FIG. It is mounted rotatably only in the J direction indicated by the arrow via a clutch (not visible in FIG. 8). Even in this case, when the solenoid 72 is turned on, the bracket 70 moves to the first position shown by the phantom line in FIG. 8 together with the separation roller 42, and the separation roller 42 rotates in the arrow A direction. Drive to.

When the solenoid 72 is turned off, the bracket 70 moves to the second position shown by the solid line in FIG. 8 together with the separating roller 42 by the urging force of the return spring 66,
Since the rotation of the separation roller 42 is stopped by the above-described one-way rotation clutch, when re-feeding the sheet on which the image is formed on one side, as in the embodiment described in FIGS. 1 to 7,
It is possible to separate the sheet into one sheet and reliably re-feed the sheet without causing a jam.

FIG. 9 is a schematic view showing an embodiment of a double-sided device in which a separating roller can be moved to a first position and a second position by using a motor. Parts corresponding to those in FIG. The same reference numerals are attached. In this double-sided device, a long hole 70a is formed at the end of the bracket 70 opposite to the side holding the separation roller 42, and a pin 76 integral with a rotary plate 75 fixed to the rotary shaft of a motor 74 is formed in the long hole 70a. Is movably fitted. Therefore, when the motor 74 is rotated by a predetermined amount in the arrow K direction, the rotating plate 75 rotates from the position shown by the solid line to the position shown by the phantom line in FIG.
6 moves, the separation roller 42 moves to the first position indicated by an imaginary line via the bracket 70.

When the motor 74 is rotated by a predetermined amount in the direction opposite to the arrow K, the rotary plate 75 returns to the position indicated by the solid line, so that the separating roller 42 and the bracket 70 are moved to the second position indicated by the solid line. Return to. Therefore, similarly to the embodiment shown in FIG. 8, the paper on one side of which the image is formed can be reliably fed to the double-sided tray, and the paper can be reliably re-fed without jam when re-fed.

FIG. 10 is a schematic view showing an embodiment of a double-sided device in which the separation roller is movable to a first position and a second position by using an eccentric cam rotated by a motor. Corresponding parts are designated by the same reference numerals. In this double-sided device, an eccentric cam 77 fixed to the rotation shaft of a motor 74 is brought into contact with an end edge 70b of the bracket 70 on the side opposite to the side where the separation roller 42 is held, and the eccentric cam 77 has an end edge 70b of the bracket 70. Is attached between the bracket 70 and the fixed portion of the apparatus. Therefore, when the motor 74 is rotated in the arrow K direction by a predetermined amount, the eccentric cam 77 rotates from the position shown by the solid line in FIG. 10 to the position shown by the phantom line, so that the bracket 70 is shown by the phantom line together with the separation roller 42. First
Rotate to the position.

When the motor 74 is rotated by a predetermined amount in the direction opposite to the arrow K, the eccentric cam 77 returns to the position shown by the solid line, so that the separation roller 42 is moved to the bracket 70.
At the same time, it returns to the second position shown by the solid line in the figure. Therefore, similarly to the embodiment of FIG. 9, the paper having the image formed on one side can be reliably fed to the double-sided tray, and
You can reliably re-feed without jam when re-feeding.

[0055]

As described above, according to the present invention, the separation roller moves to the first and second positions in response to the rotation of the feed roller in the first and second directions. If position 1 is set to a position where the separation roller is sent to the double-sided tray and the rear end of the paper can be conveyed without being caught on a guide plate, etc., the paper with an image formed on one side can be reliably sent to the double-sided tray. You can Also, when the feed roller rotates in the second direction during re-feeding, the separation roller moves to the second position. Therefore, when the feed roller re-feeds the paper in the double-sided tray, the separation roller re-feeds it. Since it does not interfere with the operation, it is possible to reliably perform re-feeding for a long time without causing a jam.

Furthermore, if the separation roller is moved to the first position and the second position according to the rotation direction of the feed roller due to the frictional force at the time of contact with the feed roller, the separation roller is removed. Since a moving mechanism for moving the first and second positions is not necessary, the number of parts can be reduced and the structure can be simplified. Further, if the separating roller is held by the swinging member, the separating roller moves to the first and second positions by swinging about the fulcrum of the swinging member. It is possible to minimize the space required for moving the holding member.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing an embodiment of a double-sided device according to the present invention together with a part of an image forming apparatus.

FIG. 2 is a perspective view showing a positional relationship of a feed roller provided in the double-sided device with respect to a sheet.

FIG. 3 is a perspective view showing a mechanism for operating a bottom plate and a feed roller of the double-sided device.

FIG. 4 is a schematic view showing a state in which a cam for rotating the bottom plate is also in a rotation position when feeding a sheet to a double-sided tray.

FIG. 5 is a schematic view showing a state in which the cam is in a rotation position when the paper is sent out from the double-sided tray.

6 is a side view showing, together with a feed roller, a mechanism for movably holding a separation roller provided in the double-sided device of FIG. 1 in a first position and a second position.

FIG. 7 is a partially sectional front view showing a mechanism for movably holding the separation roller.

FIG. 8 is a schematic view showing an embodiment of a double-sided device in which a separating roller is movable to a first position and a second position by using a solenoid.

FIG. 9 is a view showing a separation roller using a motor at a first position and a second position.
FIG. 3 is a schematic view showing an embodiment of a double-sided device which is movable to the position and.

FIG. 10 is a schematic view showing an embodiment of a double-sided device in which a separation roller is movable to a first position and a second position by using an eccentric cam rotated by a motor.

FIG. 11 is a perspective view showing an example of a feed roller and an elastic guide that comes into contact with an outer peripheral surface of the feed roller in a conventional double-sided device.

FIG. 12 is a front view showing the orientation of the leading end portion of the elastic guide when the sheets are stacked and the orientation when the paper is re-fed by a virtual line and a solid line, respectively.

FIG. 13 is a schematic view showing a state in which the direction of the tip portion of the conventional double-sided device changes while the elastic guide largely bends when the rotation direction of the feed roller changes.

FIG. 14 is a schematic diagram showing step by step a process in which a tip is cracked when the direction of the tip is changed while the elastic guide is largely bent as shown in FIG.

[Explanation of symbols]

 1: Double-sided device 12: Double-sided tray 13: Feed roller 42: Separation roller 51: Bracket P: Paper

Claims (3)

[Claims] 1. A double-sided tray for accommodating a sheet having an image formed on one side, and a first sheet for feeding the sheet into the double-sided tray.
And a separation roller that is rotatable in a second direction for feeding the paper from the double-sided tray, and a separation roller that is in contact with the feed roller, wherein the separation roller is the first roller. When the feed roller rotates in the second direction, and when the feed roller rotates in the second direction, the feed roller moves in the second position away from the double-sided tray from the first position. A double-sided device characterized by being provided so as to be movable so as to contact a roller. 2. The separation roller is moved to the first position and the second position according to the rotation direction of the feed roller by a frictional force when the separation roller comes into contact with the feed roller. The double-sided device according to claim 1, which is characterized in that. 3. The double-sided device according to claim 1, wherein the separating roller is held by a swing member.