JPH09272642A - Sheet feeder and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a sheet from being duplicately sent by constituting a projecting part, which projects from a guide face on a feeding path of a sheet and is brought in contact with a duplicately sent sheet, in such a state as being hid from the sheet feeding path, when a separation member is in such a state as separating a sheet. SOLUTION: A presser plate 1 released from its regulation, when a feeding roller 3 is driven, swings till a sheet S abuts on the feeding roller 3 and the sheet S is pressurized by the feeding roller 3 under being driven so as to be picked up. In this case, when the presser plate 1 is raised, the regulation of a rib 7b of a holder 7 is released, a separation roller 6 is pressurized by the feeding roller, and the separation roller 6 is drivenly and rotationally moved so that only an uppermost paper sheet is fed. A projecting part 4a on a sheet feeding path 9 is hid behind the separation roller 6. When the presser plate 1 is lowered in completing the separation and feeding operation of the sheet S, the separation roller 6 is also separated from the feeding roller 3, the projecting part 4a is emerged on the sheet feeding path 9, and a following sheet left in the adjacent to a sandwiching part of the separation roller 6 and the feeding roller 3 abuts on the projecting part 4a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for separating and feeding a set of sheets one by one, and an image forming apparatus using the same.

[0002]

2. Description of the Related Art Conventionally, a recording apparatus installed in an image forming apparatus such as a printer shares a sheet feeding roller and a conveying roller for the main purpose of cost reduction, and is fed by one large diameter feeding roller. There is one that carries a sheet from the paper to the recording area. This conventional recording apparatus is disclosed in, for example, Japanese Patent Laid-Open No. 1-13
As described in Japanese Patent No. 9286, a feed roller that is rotationally driven feeds a sheet from a bundle of sheets set under the feed roller to feed the sheet, and the sheet is fed along the outer circumference of the feed roller. It is configured so that it makes a U-turn, and the sheet is conveyed by the feeding roller to the recording area of the recording means provided above the feeding roller.

The feeding roller has a construction in which a plurality of rubber roller portions are fitted to the drive shaft, and is constructed so that the feeding roller having a large diameter does not become too heavy in weight. According to this, since the paper feeding / conveying unit can be configured with very few parts, the cost can be significantly reduced, and the use of the large-diameter roller enables the U-turn transportation of a considerably thick paper. Further, when a large-diameter roller is made with the same accuracy as a small-diameter roller, the error ratio with respect to the diameter is reduced, and the conveyance accuracy is improved.

On the other hand, as the paper feeding / separating means, Japanese Patent Laid-Open No. 62-
As described in Japanese Patent No. 105834, a rotatable separating roller is pressed against a driven feeding roller, a torque limiter is attached to the separating roller, and a sheet is separated by a braking torque of the torque limiter. There is.
According to this, the paper feeding / separating means using the separating pad is more durable, and stable feeding can be performed without any noise due to chatter between the pad and the paper.

Recently, the separating roller is made movable so that the separating roller is retracted from the driven feeding roller after completion of the separating and feeding operation of the sheet, and the succeeding paper separated by the separating roller continues. Have been developed to prevent the phenomenon of being drawn in (continuous transmission).

[0006]

DISCLOSURE OF THE INVENTION The present invention is a further development of the sheet separating action in the movable separation roller type, and its purpose is to effectively prevent double feeding of sheets. The present invention provides a feeding device and an image forming apparatus using the same.

[0007]

A typical structure according to the present invention for achieving the above object is a sheet supporting means for supporting a plurality of sheets, a sheet is fed from the sheet supporting means, and further an image forming means. A feeding rotary member that conveys the sheet toward a sheet, a separating member that separates a sheet between the feeding rotating member, and a separating state of the separating member and a retracted state that separates the separating member from the feeding rotary member. When the separating member is in the sheet separating state, the moving member has a moving portion and a protruding portion that protrudes from a guide surface on the sheet feeding path and can contact the multi-feed sheet. Is configured so as to be hidden from the sheet feeding path.

In the above structure, when the separating member is in the sheet separating state, a plurality of sheets set are separated and fed one by one by the action of the feeding rotating body and the separating member. At this time, since the protruding portion is hidden from the sheet feeding path, it does not interfere with the sheet feeding. On the other hand, when the separating member moves to the retracted state from the feeding rotating body, the projecting portion projects on the guide surface on the sheet feeding path, so that the sheets are fed with a medium having a large frictional force between the sheets. The succeeding sheet is stopped by the protrusion even when the sheet is fed (retracted) to the sheet. For this reason, double feeding with children is effectively prevented.

[0009]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

[First Embodiment] A first embodiment of the present invention will be described with reference to FIGS. 1 to 6. 1 is an overall perspective view of the sheet feeding device. Further, FIG. 2 is a conceptual view from the side when the separation mechanism of the same feeding device is retracted. FIG. 3 is a conceptual view from the side when the separating mechanism of the feeding device is operating. FIG. 4 and FIG. 5 are views showing only the vicinity of the separating mechanism in the conceptual view from the side when the separating mechanism is operating. Further, FIG. 6 is an explanatory diagram of an image forming apparatus using a sheet feeding device.
Here, first, the configuration of the sheet feeding device will be described.
Next, the configuration of an image forming apparatus using this sheet feeding device will be described.

{Sheet Feeding Device} The sheet feeding device according to this embodiment uses a movable separating roller using a torque limiter as a separating member.

In FIGS. 1 to 3, the pressure plate 1 has a function of pressing the sheet S on the stacker 2 against the feeding roller 3 at the time of feeding. The pressure plate 1 has a shaft 1a on the upstream side in the sheet conveying direction, is axially supported by the frame 4 by the shaft 1a, and can swing around the shaft 1a. Further, the pressure plate 1 is urged from the lower surface by a pressure plate spring 5 in the counterclockwise direction (pressing against the feeding roller 3) in FIG.

The feeding roller 3 is a feeding rotating body for picking up and feeding the sheet S and conveying the sheet S. The feeding roller 3 is rotatably supported by the frame 4 and has a rubber 3a on its surface. There is. Further, the feeding roller 4 is connected to and driven by a pulse motor (not shown).

The separation roller 6 constitutes a separation member for separating the sheet S, is axially supported by the holder 7, a clutch spring (not shown) is arranged on the shaft, and a torque of a predetermined value or more is applied. Only at this time can it rotate clockwise in FIG. Here, the separation roller 6 itself has no driving force. Further, rubber is provided on the surface of the separation roller 6.

The separating roller 6 can be moved between a sheet separating position and a retracted position by moving means. To explain this in detail, the holder 7 which rotatably supports the separation roller 6 is rotatably supported by the frame 4 by the shaft 7a and is urged by the spring 8 in the clockwise direction (pressing the feeding roller 3) in FIG. Has been done. A rib 7b is provided at the tip of the holder 7, and the rib 7b is normally regulated by the pressure plate 1 to regulate the swing of the holder 7.

However, when the pressure plate 1 swings,
The regulation of the rib 7b is also released, and the holder 7 also swings. That is, when the pressure plate 1 is raised and pressed by the feeding roller 3, the holder 7 is also raised and the separation roller 6 is pressed by the feeding roller 3 as shown in FIG. 3 (sheet separation state).
When the pressure plate 1 is lowered and retracted from the feed roller 3, the separation roller 6 is lowered together with the holder 7 as shown in FIG. 2 and retracted from the feed roller 3 (retracted state).

A sheet feeding path 9 is provided on the frame 4.
Is provided on the projecting portion 4a projecting above the guide surface. The protruding portion 4 a is for preventing the double feeding of the sheets S, and protrudes from the guide surface on the sheet feeding path 9 in the vicinity of the downstream side of the separation roller 6 on the sheet feeding path 9. It is provided in the state. During the feeding operation, that is, when the separating roller 6 is pressed by the feeding roller 3, the sheet S is hidden by the separating roller 6 and does not hinder the feeding of the sheet S. When the separating roller 6 is retracted, the sheet is retracted. It appears on the feeding path 9.

Next, the case where the sheet S is fed in the above configuration will be described. As shown in FIG. 2, in the feeding standby state, the pressure plate 1 is regulated by a regulation member (not shown), is lowered against the bias of the spring 5, and is retracted from the feeding roller 3. . Here, since the separation roller 6 is also regulated by the pressure plate 1 together with the holder 7, the separation roller 6 is lowered and is retracted from the feeding roller 3.

Next, the state at the time of feeding is shown in FIG. A pulse motor (not shown) drives the feeding roller 3 so that the feeding roller 3 is driven in the feeding direction (clockwise in FIG. 3), and the regulating member (not shown) is released to release the pressure plate 1 from the pressure plate 1. The regulation is released, and the pressure plate 1 swings counterclockwise in FIG. 3 around the shaft 1a by the biasing force of the spring 5 provided under the pressure plate 1 until the sheet S on the pressure plate 1 abuts on the feeding roller 3. Move. As a result, the sheet S on the pressure plate 1 is pressed by the driving feeding roller 3, and a frictional force is generated between the feeding roller 3 and the sheet S. The upper one sheet or a plurality of the upper sheets are picked up and fed in the rotation direction of the feeding roller 3. At this time, when the pressure plate 1 rises, the regulation of the rib 7b of the holder 7 is released, and the holder 7 is urged by the spring 8 to move the shaft 7a.
3, the separation roller 6 is pressed by the feeding roller 3, and the frictional force causes the separation roller 6 to rotate following the clockwise direction in FIG. Further, at this time, as described above, the protrusion 4a on the sheet feeding path 9
Is hidden by the separation roller 6 and does not hinder the progress of the fed sheet S.

On the other hand, as shown in FIG. 4, the sheet S is sent by the feeding roller 3 to the pressure contact portion between the separation roller 6 and the feeding roller 3. At this time, when there is only one sheet S between the feeding roller 3 and the separation roller 6, the rotation torque acting on the separation roller 6 becomes larger than a predetermined value such that it exceeds the braking torque of the clutch spring. The separation roller 6 is driven by the rotation of the feed roller 3. On the other hand, when there are two sheets S between the feeding roller 3 and the separation roller 6, the rotational torque acting on the separation roller 6 is blocked by the braking force of the clutch spring. Therefore, the lower sheet Sb of the two sheets S between the feeding roller 3 and the separating roller 6 is stagnated by the separating roller 6, and only the upper sheet Sa is fed by the feeding roller 3. To be done.

When the sheet S is nipped by the pinch rollers on the downstream side of the separating roller 6 and the separating / feeding operation is completed, the pressure plate 1 starts to be lowered by the regulating member (not shown),
At the same time, the separation roller 6 is also separated from the feeding roller 3, and the protruding portion 4 a appears on the sheet feeding path 9. At this time, as shown in FIG. 5, the separated succeeding sheet Sb remains in the vicinity of the sandwiching portion between the separating roller 6 and the feeding roller 3.

If there is no protrusion 4a,
When the separation roller retracts, the frictional force that has stopped the succeeding sheet Sb disappears, so there is a risk that the succeeding sheet Sb will be pulled in (double feeding) by the frictional force with the fed sheet Sa. However, according to the present embodiment, the succeeding sheet Sb that is about to be pulled in strikes against the leading end of the protrusion 4a on the sheet feeding path 9. At this time, the succeeding sheet Sb stops at the leading end of the protruding portion 4a, so that it is possible to effectively prevent double feeding.

As described above, in this embodiment, even when a medium having a large coefficient of friction between sheets is fed,
By providing the protruding portion 4a on the sheet feeding path 9, it is possible to prevent the succeeding sheet Sb by the protruding portion 4a after the separation roller is retracted and effectively prevent the double feeding. Also,
At the time of feeding / separating, the sheet is hidden by the separating roller 6 and therefore does not hinder the sheet feeding.

[Image Forming Apparatus] FIG. 6 shows an example of an image forming apparatus using the above-described sheet feeding apparatus.
The image forming apparatus conveys the sheet S fed by the sheet feeding apparatus described above to the image forming means by the feeding roller 3 and the pinch roller 10 to form a predetermined image.

The image forming means of this embodiment uses an ink jet recording system, and the carriage 11 is capable of reciprocating in the direction perpendicular to the paper surface of FIG.
Further, an inkjet recording head 12 capable of ejecting ink according to an image signal is mounted. As a result, the carriage 11 is moved with respect to the conveyed sheet S, ink is ejected from the recording head 12 to perform image recording, and the sheet S is ejected to the ejection stacker 14 by the ejection roller pair 13.

Further, this image forming apparatus has a document reading section at the upper part of the apparatus, and the document G is conveyed by the conveying roller 15 and the information written on the document G conveyed by the optical system 16 is read. The information can be transmitted to the image forming means or the image forming means of another image forming apparatus.

The image forming means is not limited to the ink jet recording system, and various other systems such as electrophotographic system and thermal transfer recording system may be used.

[Second Embodiment] Next, another embodiment of the sheet feeding apparatus will be described with reference to FIG. The apparatus according to this embodiment is provided with a return lever 17 which is a return member for pushing back the succeeding sheet Sb in the vicinity of the protruding portion 4a of the first embodiment described above, and other configurations are the same as those of the first embodiment. Since they are the same, members having the same functions as those in the first embodiment are designated by the same reference numerals, and duplicate description will be omitted.

In FIG. 7, the return lever 17 is a swing shaft 17a.
It is attached to the frame 4, the holder 7 or the like in the vicinity of the projecting portion 4a so as to be swingable around. Further, the return lever 17 is biased to the upstream side in the feeding direction by the tension spring 18 and is in contact with the stopper 19 as shown by the chain double-dashed line in FIG. 7.

In the above structure, the case of feeding the sheet S will be described. In the feeding standby state, the separation roller 6 (not shown in FIG. 7) is fed from the feeding roller 3 similarly to the first embodiment. It is in a retracted state. At this time, the return lever 17 is biased by the spring 18 and is in contact with the stopper 19.

Next, in the feeding state, the pressure plate 1 is swung by the biasing force of the spring 5 until the sheet S on the pressure plate abuts against the feeding roller 3, and the sheet S is driven.
The uppermost one of the sheets S on the stacker 2 or a plurality of upper sheets of the sheets S are picked up by the frictional force with the feeding roller 3 and are fed in the rotation direction of the feeding roller 3. . At this time, the separation roller is pressed by the feeding roller 3 and the protruding portion 4 on the sheet feeding path 9 is also pressed.
Since a is hidden by the separation roller 6, it does not hinder the progress of the fed sheet S.

On the other hand, as shown in FIG. 7, the sheet S is sent by the feeding roller 3 to the pressure contact portion between the separation roller 6 and the feeding roller 3 to separate the sheets. After that, the sheet S
Hits the return lever 17 on the feed path 9. At this time, the uppermost sheet Sa is the separation roller 6 and the feeding roller 3
Since it is sandwiched between the return lever 17 and the spring 18, the return lever 17 is pushed to the downstream side in the feeding direction against the bias of the spring 18 (state shown by the solid line in FIG. 7) and fed.

When the sheet S is nipped by the pinch roller 10 on the downstream side of the separating roller and the separating / feeding operation is completed, the separating roller 6 is separated from the feeding roller 3 and the projecting portion 4a is formed in the sheet feeding path. Appears on 9. At this time, as shown in FIG. 7, the separated succeeding sheet Sb remains in the vicinity of the sandwiching portion between the separating roller 6 and the feeding roller 3, but it may be pulled in as described in the first embodiment. Since the succeeding sheet Sb hits the leading end of the projecting portion 4a on the sheet feeding path 9, double feeding can be prevented.

In this embodiment, when the first sheet Sa passes over the return lever 17, the return lever 17
Since the spring 17 is biased by the spring 18 toward the upstream side in the feeding direction, the spring 17 returns to the position where it abuts against the stopper 19 (two-dot chain line in FIG. 7). At this time, the succeeding sheet Sb remaining in the vicinity of the leading end of the protruding portion 4a is returned to the top of the feeding stacker 2 by being pushed upstream by the return lever 17 in the feeding direction. Accordingly, when the friction coefficient between the sheets is large, it is possible to effectively prevent the leading edge of the sheet from being bent due to the succeeding sheet Sb having the leading edge abutting against the protruding portion 4a being pulled by the conveyance of the first sheet Sa. Therefore, stable feeding can be performed.

That is, in this embodiment, even when a medium having a large coefficient of friction between the sheets is fed, the protrusion 4a is provided on the sheet feeding path 9 so that the separating roller 6 is retreated after the retreat.
The projecting portion 4a can prevent the succeeding sheet Sb, effectively prevent the double feeding, and at the time of feeding / separating, the sheet is hidden by the separation roller 6 and thus does not hinder the feeding of the sheet. Further, in the present embodiment, the succeeding sheet remaining in the vicinity of the protruding portion 4a is returned to the top of the feeding stacker 2 by the return lever 17, so that the leading edge of the sheet can be effectively prevented and stable feeding is possible. It can be performed.

Other Embodiments In the above-described embodiment, an example in which a separating roller that can rotate when a load of a certain amount or more is applied by the torque limiter is used as the separating member is shown. It does not necessarily rotate but may be, for example, a separating pad.

Further, the feeding rotating body is not limited to the roller-like one as in the above-mentioned embodiment, but may be constituted by a rotating belt or the like.

Further, the above-described sheet feeding apparatus can be suitably used not only for the image forming apparatus, but also for a reading apparatus for separately feeding and reading a plurality of originals one by one. .

[0039]

As described above, the present invention can effectively prevent the double feeding caused by the retraction of the separating member, and improve the reliability of the feeding mechanism. Therefore, in the image forming apparatus using the sheet feeding device according to the present invention, smooth image formation can be performed without causing double feeding.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a sheet feeding device showing an embodiment of the present invention.

FIG. 2 is a conceptual view from the side when the separation roller of the sheet feeding device according to the embodiment of the present invention is in the retracted state.

FIG. 3 is a conceptual view from the side when the separation roller of the sheet feeding device according to the embodiment of the present invention is in the separation state.

FIG. 4 is a partially enlarged conceptual view from the side when the separation roller of the sheet feeding device according to the embodiment of the present invention is in the separation state.

FIG. 5 is a partially enlarged conceptual view from the side when the separation roller of the sheet feeding device according to the embodiment of the present invention is in the retracted state.

FIG. 6 is an overall explanatory view of an image forming apparatus using the sheet feeding device according to the present invention.

FIG. 7 is a conceptual view from the side of a sheet feeding device showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Pressure plate 1a ... Shaft 2 ... Stacker 3 ... Feed roller 3a ... Rubber 4 ... Frame 4a ... Projection part 5 ... Pressure plate spring 6 ... Separation roller 7 ... Holder 7a ... Shaft 7b ... Rib 8 ... Spring 9 ... Sheet feeding path 10 ... Pinch roller 11 ... Carriage 12 ... Recording head 13 ... Ejection roller 14 ... Ejection stacker 15 ... Original conveying roller 16 ... Optical system 17 ... Return lever 17a ... Shaft 18 ... Spring 19 ... Stopper

Claims (5)

[Claims] 1. A sheet supporting means for supporting a plurality of sheets, a feeding rotating body for feeding the sheet from the sheet supporting means, and further conveying the sheet toward the image forming means, and a sheet between the feeding rotating body. A separating member for separating the sheet, a moving unit that moves the separating member between a sheet separating state and a retracted state in which the separating member is separated from the feeding rotating body, and a moving member that projects from a guide surface on the sheet feeding path, A sheet feeding device, comprising: a protrusion capable of contacting a sheet to be fed, wherein the protrusion is configured to be hidden from a sheet feeding path when the separating member is in a sheet separating state. 2. The sheet feeding apparatus according to claim 1, wherein the projecting portion is provided in the vicinity of the separating member and on the downstream side of the separating member in the sheet feeding direction. 3. The sheet feeding apparatus according to claim 1, wherein the separating member is a rotating member that can rotate when a load of a certain amount or more is applied. 4. A return member for pushing back a sheet that has been double-fed when the separation member moves from the sheet separation state to the retracted state is provided in the vicinity of the protruding portion. The sheet feeding device according to claim 3. 5. An image forming apparatus for forming an image on a fed sheet, the sheet feeding apparatus according to claim 1, and the sheet fed by the sheet feeding apparatus. An image forming apparatus comprising: an image forming unit that forms an image on the image forming apparatus.