JP3322753B2 - Duplex unit of image forming apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer,
Regarding a duplex unit of an image forming apparatus such as a facsimile,
In particular, the present invention relates to a double-sided unit having an elastic guide whose leading end is in contact with a feed roller in order to improve the transportability of the transfer paper fed into and out of the double-sided unit.

[0002]

2. Description of the Related Art For example, some copiers include a duplex unit 1 used for forming images on both sides of a transfer sheet as shown in FIG. The two-sided unit 1 includes a two-sided tray 2 on which transfer paper having an image formed on one side is stacked, a feed roller 3 rotatable in both forward and reverse directions, and a separation roller which rotates while contacting the feed roller 3. 6, an elastic guide 4 provided to improve the transportability of the transfer sheet P which is fed to the double-sided tray 2 and whose end comes into contact with the feed roller 3 and is re-fed from the double-sided tray 2; When the transfer paper P is sent out from the tray 2, the transfer paper P on the double-sided tray 2 is brought into contact with the feed roller 3.

When the transfer paper P having an image formed on one side is stacked (stacked) on the double-sided tray 2, the feed roller 3 rotates in the direction indicated by the solid line in FIG. The transfer paper P conveyed thereby is sequentially stacked on the bottom plate 5 at the lower position in the double-sided tray 2. At this time, the tip of the elastic guide 4 follows the direction of rotation of the feed roller 3 so that it is oriented as shown by a solid line in FIG.

[0004] When the stacking of the transfer paper P in the double-sided tray 2 is completed, the feed roller 3 rotates reversely in the direction of the arrow shown by the broken line, and the feed roller 3 functions as a paper feed roller and a separation roller. Further, the bottom plate 5 rotates to a raised position indicated by a phantom line in the figure, and the uppermost transfer paper P stacked thereon is brought into contact with the feed roller 3.

Accordingly, the uppermost transfer paper P is re-fed while being separated into one sheet. At this time, the elastic guide 4
Since the tip follows the rotation direction of the feed roller 3,
The direction changes as shown by a virtual line.

[0006]

However, in the case of such a double-sided unit having an elastic guide whose leading end abuts on the outer peripheral surface of the feed roller, the transfer roller is rotated in the reverse direction after the transfer paper is stacked in the double-sided tray. In some cases, inconvenience may occur when the transfer paper is re-fed.
That is, as shown in FIG. 10, after the transfer paper P is stacked in the double-sided tray 2, the elastic guide 4 has a leading end indicated by a solid line in the direction in which the feed roller 3 is rotating. Orientation (left).

In this state, the bottom plate 5 moves to the rising position indicated by the imaginary line in FIG. 3 when re-feeding, so that the leading end of the transfer paper P located at the highest position contacts the feed roller 3, and
It is pressed with a pressure suitable for paper feeding. Therefore,
In this state, the leading end of the elastic guide 4 and the leading end of the transfer paper P are both in contact with the feed roller 3.

In this state, when the feed roller 3 is reversely rotated in the direction indicated by the broken line for re-feeding the paper, the elastic guide 4 and the transfer paper P which are in contact with the feed roller 3 as shown in FIG. Are simultaneously moved to the right in the same figure, so that the leading end of the transfer paper P curls as shown in FIG.
When the sheet is fed to the separation position where the separation roller 6 is located, the sheet is pinched when the sheet is pinched.

When the width of the elastic guide 4 is formed so as to substantially correspond to the width of the feed roller 3 as shown in FIG. 13, for example, the bent end portion is formed at a portion corresponding to the width of the elastic guide 4. Occurs, and as a result, it may cause a transport jam, or even if the jam does not occur,
However, there is a problem because the image is not transferred to the printer.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an elastic guide having a leading end contacting a feed roller in order to improve the transferability of a transfer sheet. Another object of the present invention is to prevent the transfer paper from being bent.

[0011]

According to the present invention, in order to achieve the above object, in a double-sided unit of an image forming apparatus as described above, when a transfer sheet is fed from a double-sided tray, the bottom plate is moved by a bottom plate moving means. Before the transfer paper on the double-sided tray comes into contact with the feed roller, means for rotating the feed roller in the second direction to change the direction of the tip of the elastic guide to the direction corresponding to the second direction is provided.
The means, the feed roller and the bottom plate moving means
Are driven by the same drive source, and the bottom plate moving means is driven by
So that the torque from the power source is transmitted through the speed reduction mechanism
The drive source drives the feed roller in the second direction.
The bottom plate moving means through the speed reduction mechanism.
It moves so that the bottom plate moves with a delay to the ascending position .

[0012]

[0013]

According to the double-sided unit of the image forming apparatus constructed as described above, when re-feeding the transfer paper fed to the double-sided tray, the bottom plate is moved to the raised position by the bottom plate moving means, and the double-sided tray is moved. Before the transfer paper is brought into contact with the feed roller, the front end of the elastic guide is changed to a direction corresponding to the second direction by rotating the feed roller in a second direction for sending the transfer paper from the double-sided tray. Therefore, the transfer paper sent from the double-sided tray is re-fed while being guided by the elastic guide without difficulty. Therefore, the leading end of the re-fed transfer paper does not break.

Further, by driving the feed roller and the bottom plate moving means by the same driving source, and its bottom plate moving means are as rotational force from the driving source is transmitted via a speed reduction mechanism
Because, when the drive source rotates the feed roller in the second direction, the bottom plate moving means via the reduction mechanism so the bottom plate is operated to move behind the raised position,
With a simple mechanism that only increases the reduction ratio of the reduction mechanism, the feed roller can be rotated in the second direction before the transfer paper on the double-sided tray comes into contact with the feed roller. Therefore, there is no need to perform any timing control or the like.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a configuration diagram showing a duplex unit of an image forming apparatus according to an embodiment of the present invention. The duplex unit 10 of the image forming apparatus includes a double-sided tray 12 having a movable bottom plate 15 on which a transfer sheet P on which an image is formed is loaded on one side, and a transfer sheet P to which the transfer sheet P is fed. 1 and the transfer paper P from the double-sided tray 12 thereof.
And a feed roller 13 rotatable in a second direction opposite to the direction indicated by the arrow A for sending out.

Further, an elastic guide 14 whose leading end abuts on the feed roller 13 and whose direction is changed to a direction corresponding to the first or second direction according to the rotation direction of the feed roller 13, a double-sided tray When the transfer paper P is sent out of the tray 12, the transfer paper P on the double-sided tray 12 is brought into contact with the feed roller 13. The bottom plate is moved by pivoting the bottom plate 15 about the fulcrum 21 to a raised position indicated by a virtual line in FIG. Means 11.

The double-sided unit 10 moves the transfer paper P, which has been fed onto the double-sided tray 12 by the feed roller 13 and the separation roller 42 pressed and rotated against the same, toward and away from each other in FIG. A pair of side fences (not shown) for aligning the position in the paper width direction with respect to the paper feeding direction by repeating (jogging operation), and the leading end of the transfer paper P sent to the double-sided tray 12 (the trailing end when re-feeding). 1, the end fence 43 which can reciprocate in the left-right direction in FIG.

The feed roller 13 is attached to the feed roller shaft 16 by a later-described attachment method so as to come into contact with the vicinity of the transport center of the transfer paper P to be fed at a predetermined width as shown in FIG.

The elastic guide 14 is formed of, for example, a flexible resin film, and has a width substantially corresponding to the length of the feed roller 13 in the axial direction. The entire area of the tip is the feed roller 13
Is in contact with the roller surface with a contact pressure that does not hinder the rotation of the feed roller 13 due to the elastic force of the material itself.

When the transfer paper P is sent out from the double-sided tray 12 in FIG. 1, the transfer paper P on the double-sided tray 12 is rotated by the bottom plate moving means 11 rotating upward. Before contacting the feed roller 13, the feed roller 13 is rotated in the second direction opposite to the arrow A to change the direction of the tip of the elastic guide 14 to the second direction.
(The tip is directed rightward in FIG. 1).

FIG. 3 is a perspective view showing a mechanism for operating the feed roller 13 and the bottom plate 15 in such a manner. In this mechanism, the feed roller 13 and the bottom plate moving means 11 are driven by a motor 22 which is the same drive source. The bottom plate moving means 11 reduces the rotational force from the motor 22
Is transmitted to the lever holding shaft 39, and the pressing lever 37 fixed thereto is rotated to rotate the bottom plate 15 about the fulcrum 21 (FIG. 1).

When the motor 22 rotates to rotate the feed roller 13 in the second direction shown by the arrow B, the bottom plate moving means 11 operates via the speed reduction mechanism 23, and the bottom plate 15
Is moved by the speed reduction mechanism 23 with a delay to an ascending position (position changes according to the number of transfer papers stacked on the bottom plate 15) indicated by a virtual line in FIG.

As shown in FIG. 3, the speed reduction mechanism 23 is composed of a number of gears arranged in a train, and a drive gear 24 fixed to a rotating shaft of a motor 22 has a large size of a first idle gear 25. The large diameter portion of the second idle gear 26 meshes with the small diameter portion of the first idle gear 25.

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. The input gear 28 is meshed with a gear 31 for sequentially transmitting the rotational force from the motor 22 to another drive system, and the gears 32 and 33 are sequentially meshed with the gear 31.

A cam 29 is mounted on the input gear 28 via a clutch 30 that idles when a predetermined load or more is applied. A pin 34 is attached to the cam 29 at a position eccentric from the center of rotation. One end of a pressure spring 35 is attached to the pin 34.

The other end of the pressure spring 35 is attached to an arm 36 fixed to one end of a lever holding shaft 39 rotatably held at a fixed portion of the duplex unit. The lever holding shaft 39 fixes one end of a pressure lever 37 for rotating the bottom plate 15 at a position substantially corresponding to the transfer center of the transfer sheet.

On the other hand, a roller drive gear 38 meshes with a small diameter portion of the second idle gear 26. The roller drive gear 38 is connected to one end of the feed roller shaft 16 rotatably held by a fixed portion of the duplex unit. Fixed
The feed roller 13 is attached to the feed roller shaft 16 by an attachment method described later.

The image forming apparatus having the double-sided unit 10 shown in FIG. 1 configured as described above is illustrated when a double-sided image forming mode for forming an image on both sides of a transfer sheet is selected and an image forming operation is started. A toner image is formed on one side of the transfer paper P by an image forming unit not to be formed, and is transported to the fixing unit 17 in an unfixed state, where the toner image is fixed.

The transfer paper P is transported by the branch claw 18 switched to the position shown by the imaginary line in FIG.
To the horizontal transport path 41 in the duplex unit 10.
And is fed onto the double-sided tray 12 by the conveying force of the feed roller 13 and the separation roller 42. Immediately after the transfer paper P has been sent onto the double-sided tray 12, the transfer paper P is moved by a side fence and an end fence 43 (not shown)
The front, rear, left and right positions are aligned. In the case of forming a plurality of double-sided images, this series of operations is repeatedly performed.

When all of the indicated number of sheets are stacked on the double-sided tray 12 in this manner, the bottom plate 15 rotates the transfer paper P on the double-sided tray 12 in the direction opposite to the arrow A in FIG. It rotates to the ascending position indicated by the imaginary line that comes into contact with the feed roller 13. As a result, the transfer paper P is re-fed sequentially from the topmost paper.

This re-feeding is performed in a state where the transfer paper P on the double-sided tray 12 is aligned in front, rear, left and right by the pair of side fences and the end fence 43. Do not become.

The rotation of the bottom plate 15 and the rotation of the feed roller 13 are performed by the same motor 22 as described with reference to FIG. Is feed roller 1
As described above, when the sheet 3 is rotated in the refeeding direction (second direction) indicated by the arrow B, the bottom plate 15 moves with a delay to the ascending position.

That is, in the duplex unit 10 according to this embodiment, when the motor 22 rotates in the direction of arrow C in FIG. When the motor 22 is stacked on the tray 12, the motor 22 rotates in the direction opposite to the arrow C, and the sheet re-feed operation starts.

As a result, the drive gear 24 rotates clockwise in FIG. 3, and the first idle gear 2
5 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 therewith.

The second idle gear 26 also meshes with a third idle gear 27. The third idle gear 27 meshes with an input gear 28 provided with a cam 29 for rotating the bottom plate 15. Therefore, the input gear 28 simultaneously rotates clockwise in FIG.

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

The cam 29 has contact portions 29a and 29b formed at positions on the outer periphery thereof which are different from each other by 180 ° in phase. When 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.

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

Accordingly, the lever holding shaft 39 rotates in the same direction, and the pressing lever 37 fixed thereto rotates in the same direction.
Is rotated to the ascending side, and the uppermost transfer paper stacked on the bottom plate 15 is moved to the ascending position indicated by a virtual line in FIG. The movement of the bottom plate 15 to the raised position is performed by the speed reduction mechanism 23.
Therefore, the feed roller 13 is delayed from the timing at which the feed roller 13 starts rotating in the direction opposite to the direction indicated by the arrow A in FIG.

Therefore, the elastic guide 14 is provided on the transfer paper P
After stacking on the double-sided tray 12, feed roller 1
3 is oriented along the direction in which it was rotating (in FIG. 1, the leading end is directed to the left). When the sheet is re-fed in contact with the transfer sheet, as described with reference to FIGS. 11 to 13, the transfer sheet may be easily broken at the leading end. However, according to this embodiment, this can be prevented.

That is, in this embodiment, the double-sided tray 1
When re-feeding the transfer paper P sent to the feed tray 2, the bottom plate 15 is moved to the above-mentioned raised position by the bottom plate moving means 11, and before the transfer paper on the double-sided tray 12 abuts on the feed roller 13, Feed roller 13 is moved to double-sided tray 12
1 is rotated in the direction opposite to the direction indicated by the arrow A in FIG. 1 to change the direction of the tip of the elastic guide 14 to the transfer paper sending side (the direction corresponding to the second direction). The fed transfer paper P is re-fed while being smoothly guided by the elastic guide 14 whose direction has been changed.

Accordingly, the leading edge of the re-transferred transfer paper P does not break. When the cam 29 is rotated counterclockwise from the position shown in FIG. 5 to the position shown in FIG. 4, the pressing lever 37 is rotated clockwise in FIG. Because it is energized,
The urging force returns to the illustrated position, and the bottom plate also returns to the illustrated position by its own weight.

In this embodiment, when a paper jam (jam) occurs at the feed roller 13,
The structure is such that the transfer paper can be easily taken out without breaking.

The configuration and operation will be described below with reference to FIGS. As shown in FIGS. 6 and 7, the feed roller 13 has a center hole 47 for rotatably fitting the feed roller shaft 16 in the axial direction. The hub groove 47a is formed within a predetermined angle range in the direction. The hub groove 47a
Although the diameter of the groove is larger than the diameter of the center hole 47, the hub walls 47b and 47c (see also FIG. 8) are formed by partially setting the diameter of the groove to be the same as the diameter of the center hole 47. .

A pin 48 is attached to the feed roller shaft 16.
When the feed roller shaft 16 is fitted into the center hole 47 of the feed roller 13, the pin 4
8 rotates within a predetermined angle range in which it contacts the hub walls 47b and 47c in the hub groove 47a.

Then, the feed roller shaft 16
Is inserted into the center hole 47 of the feed roller 13 and, for example, C is inserted into the annular grooves 16a and 16b as shown in FIG.
Retaining members 49, 5 such as rings or E-rings
0 is inserted so that the feed roller 13 does not shift in the axial direction with respect to the feed roller shaft 16 in the assembled state.

Since the feed roller 13 is attached to the feed roller shaft 16 in such a configuration, the feed roller 13 has a positional relationship between the hub groove 47a and the pin 48 of the feed roller shaft 16 as shown in FIG. when,
As shown in FIG. 9, in the direction of arrow B, the pin 48 is attached to the hub wall 47c.
Can rotate freely (idle) with respect to the feed roller shaft 16 until it comes into contact with the feed roller shaft 16.

Therefore, when the feed roller is directly connected to the feed roller shaft, and when the paper is jammed in the feed roller portion and the transfer paper is to be pulled out and taken out, a drive including a motor is provided via the feed roller. By turning the system all the way, a large force is required, and it was easy to break the transfer paper,
According to this embodiment, since the feed roller 13 is provided with the relative rotation area with respect to the feed roller shaft 16 as described above, only the feed roller 13 is freely rotated within the rotatable range, thereby causing a transfer in which a paper jam occurs. You can take out the paper.

When the transfer paper is stacked on the double-sided tray 12, the feed roller shaft 16 rotates in the direction of arrow A while the pin 48 contacts the hub wall 47c as shown in FIG. When the feed roller 13 rotates in the same direction and the paper is fed again, as shown in FIG. 8, the pin 48 rotates in the direction of arrow B while abutting on the hub wall 47b, thereby rotating the feed roller 13 in the same direction. Rotate in the direction.

When the rotation of the feed roller shaft 16 is changed from the rotation in the stacking direction to the rotation in the paper re-feeding direction (or vice versa), only the feed roller shaft 16 rotates to feed. There is an idling area where the roller 13 does not rotate (a predetermined angle range in which the hub groove 47a is formed), but if this idling area is reduced, an elastic guide for re-feeding the transfer paper after the stacking of the transfer paper is completed. 1
The direction of the tip 4 can be changed more quickly.

It should be noted that even if the idling area is provided as described above, FIG.
If the number of teeth of the input gear 28 of the reduction mechanism 23 shown in the description is increased to increase the reduction ratio, the movement of the bottom plate 15 to the ascending position (the position shown by the phantom line in FIG. 1) can be delayed. The transfer paper on the double-sided tray 12 is
Before contacting the feed roller 3, the feed roller 13 can be rotated in the direction of arrow B to change the direction of the tip of the elastic guide 14 (FIG. 2).

As described above, in this embodiment, the operation of rotating the feed roller 13 before the transfer paper is brought into contact with the feed roller 13 by moving the bottom plate 15 to the raised position when re-feeding the paper is described. Although this is realized by a simple mechanical mechanism that only increases the speed reduction ratio of the speed reduction mechanism 23, it may be performed by timing control using a microcomputer or the like.

[0053]

As described above, according to the present invention, when the transfer paper fed to the double-sided tray is re-fed, the feed roller rotates in the second direction in which the transfer paper is fed, and the elastic guide. The transfer paper on the double-sided tray abuts on the feed roller and is re-fed, after changing the direction of the leading end of the transfer paper to the direction corresponding to the second direction. Can be re-fed.

[0054] Further, by driving the feed roller and the bottom plate moving means by the same driving source, and its bottom plate moving means are as rotational force from the driving source is transmitted via a speed reduction mechanism
Runode, with a simple mechanism of simply increasing the reduction ratio of the reduction mechanism, the transfer paper on the duplex tray can be delayed to abut against the feed roller. Therefore, it is possible to prevent the leading end of the transfer paper re-fed from the double-sided tray by using only the above-mentioned mechanism without using a control device for performing the timing control.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating a duplex unit of an image forming apparatus according to an embodiment of the present invention, together with a part of the image forming apparatus.

FIG. 2 shows a feed roller 13 also provided in the double-sided unit and an elastic guide 14 whose leading end is in contact with the feed roller 13;
FIG.

FIG. 3 is a perspective view showing a mechanism for driving a feed roller 13 and a bottom plate 15 of the duplex unit in FIG.

FIG. 4 is a schematic view showing a state in which a cam 29 for rotating the bottom plate 15 is at a rotating position when a transfer sheet is fed to a double-sided tray.

FIG. 5 is a schematic view showing a state where the cam 29 is at a rotating position when the transfer paper is sent out from the double-sided tray.

FIG. 6 is a perspective view for explaining a structure for attaching a feed roller 13 to a feed roller shaft 16;

FIG. 7 is a longitudinal sectional view showing a state in which the feed roller 13 is assembled to a feed roller shaft 16;

FIG. 8 shows a feed roller shaft 16 for re-feeding the transfer paper.
FIG. 3 is a schematic diagram illustrating a positional relationship between a feed roller and a feed roller in a rotation direction.

FIG. 9 is a schematic diagram showing a positional relationship in the rotation direction between a feed roller shaft 16 and a feed roller 13 when transfer papers are stacked on a double-sided tray.

FIG. 10 is a schematic diagram illustrating an example of a duplex unit provided in a conventional copying machine.

FIG. 11 is a schematic diagram showing a state where re-feeding is started in a conventional duplex unit.

FIG. 12 is a schematic diagram for explaining a state in which the leading end of the transfer sheet is curled and the leading end is broken after the re-feed.

FIG. 13 is a schematic view showing a state in which the tip is broken at a width corresponding to the elastic guide.

[Explanation of symbols]

 10: Double-sided unit 11: Bottom plate moving means 12: Double-sided tray 13: Feed roller 14: Elastic guide 15: Bottom plate 22: Motor (drive source) 23: Reduction mechanism P: Transfer paper

Continuation of front page (58) Fields investigated (Int. Cl. ⁷ , DB name) G03G 15/00 G03G 21/00 G03G 21/14 B65H 1/00-3/68 B65H 83/00-85/00

Claims (1)

(57) [Claims] 1. A transfer sheet on which an image is formed on one side is stacked.
A double-sided tray having a movable bottom plate and a double-sided tray
The first direction to feed the transfer paper and transfer from the double-sided tray
Feed roller rotatable in a second direction for feeding paper
And the tip of the feed roller abuts on the feed roller.
The direction of the tip depends on the rotation direction of the
An elastic guide that can be changed to a direction corresponding to the direction,
When transferring the transfer paper from the double-sided tray,
Move the paper to the raised position where it touches the feed roller.
Image forming apparatus provided with bottom plate moving means for moving the bottom plate
When transferring the transfer paper from the double-sided tray,
Transfer on the double-sided tray by moving the bottom plate by moving means
Before the paper abuts the feed roller, the feed
The roller is rotated in the second direction to rotate the elastic guide.
Hand for changing the direction of the tip to the direction corresponding to the second direction
StepProvided, Said means, said feed roller and said bottom plate moving means
Driven by the same drive source, the bottom plate moving means is
The torque from the drive source is transmitted via the speed reduction mechanism
Wherein the drive source drives the feed roller to the second position.
When rotated in the direction of, the bottom through the speed reduction mechanism
The plate moving means is activated and the bottom plate is delayed to the raised position.
Moved And an image forming apparatus.
Surface unit.