JP2001019194A - Sheet feeder, recorder and paper feed method for sheet feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the deterioration of separating feed performance and reduce the effects of back tension in a simple constitution. SOLUTION: When a sheet supported by a pressure plate 4 to press abut to a paper feed roller 1 is fed out to be separated sheet by sheet by a separating pad 6, the pressure plate 4 is separated from the paper feed roller 1 when the sheet is separated, after the separated sheet is conveyed by a conveying means in the downstream, the separating pad 6 is separated from the paper feed roller 1, and also, a relative angle of the separating pad 6 to a sheet on and after the second is changed so as to be larger than an angle initially set for a separating feed. In this way, back tension of the conveyed sheet can be decreased, and the double feed of the sheet also can be surely prevented.

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 provided in a printing device such as a printer.

[0002]

2. Description of the Related Art FIGS. 4 to 6 show an example of a conventional sheet feeding apparatus. FIG. 4 shows a sheet feeding standby state of the sheet feeding apparatus, and FIG. 5 shows a sheet feeding state.

In FIG. 4, reference numeral 1 denotes a paper feed roller;
Is a drive shaft for rotating the paper feed roller 1. The rotation of the drive shaft 2 is transmitted from a drive source such as a motor (not shown) via a drive transmission mechanism described later in detail. Reference numeral 3 denotes a frame constituting the sheet feeding device, 4 denotes a pressing plate for pressing the loaded printing medium (hereinafter referred to as recording paper) P against the paper feed roller 1, and 5 denotes a predetermined pressing force to the pressing plate 4. Is a pressure plate spring for providing The pressure plate 4 is rotatably supported on the frame 3 by a fulcrum 4a. Reference numeral 3a denotes an abutment wall formed on the frame 3, which receives a load on the front end side of the recording paper P supported obliquely and regulates its position.

FIG. 4 shows a state in which the recording paper P is set in a standby state of the sheet feeding device, and the stacking angle θ at this time is shown.
In the sheet feeding apparatus having this kind of configuration, the angle formed with the horizontal is generally about 3 to facilitate the setting of the sheet bundle.
It is set between 0 degrees and about 60 degrees.

Reference numeral 6 denotes a separation pad which is held by a pad frame 7 which can rotate around a fulcrum 7a. Also,
The separation pad 6 is pressed against the paper feed roller 1 by a separation spring 8, and a predetermined pressure required for separation is applied between the separation pad 6 and the paper feed roller 1.

[0006] Reference numerals 10 a and 10 b denote paper feed guides, and the recording paper P fed by the paper feed roller 1 and the separation pad 6.
Is guided to a nip portion constituted by the transport roller 11 and the pinch roller 12. The recording paper P guided to the nip is conveyed with specified accuracy by the rotation of the conveying roller pairs 11 and 12. Reference numeral 13 denotes an ink-jet print head, and reference numeral 14 denotes a platen, both of which constitute a printing unit. Reference numeral 15 denotes a paper discharge roller, and reference numeral 16 denotes a pinch roller for generating a paper discharge force. In the case of an inkjet printer or the like, a spur roller or the like is used to prevent transfer of ink.

FIG. 6 shows a drive transmission mechanism provided outside the frame 3, and shows a release state (a state shown in FIG. 4) in which the pressure plate 4 is separated from the paper feed roller 1. Driving from a driving source (not shown) is performed by a gear train 20,
The power is transmitted to a gear 22 fixed to the drive shaft 2 via 21 to rotate the paper feed roller 1. Gear 23 has cam 23
Are provided so as to rotate integrally with each other.
The cam 23 rotates in synchronization with the rotation of the cam 23.

The pressure plate 4 is provided with a pressure plate cam 4b which can be engaged with the cam 23. When the pressure plate cam 4b is pushed down by the cam 23, it is released. Then, when the sheet feeding operation is started, the gear 22 rotates in the direction of C, and the cam 23 is disengaged from the pressure plate cam 4b to reach the position shown by the one-dot chain line in the figure, so that the pressure plate 4 is supplied by the pressure plate spring 5. The recording paper is urged in the direction of pressing against the paper roller 1, and the stacked recording paper is pressed against the paper feed roller 1.

Hereinafter, the separation and feeding operation of the conventional sheet feeding apparatus will be described.

When the pressure plate 4 is in the release state shown in FIG. 4, the recording paper P to be fed is inserted and held in a paper feed hopper constituted by the pressure plate 4, the abutting wall 3a and the frame 3. Next, as shown in FIG. 5, when the sheet feeding operation is started, as described above, the pressure plate 4 is urged toward the sheet feeding roller 1 by the pressure plate spring 5, and the recording paper P stacked on the pressure plate 4 is fed. Press against roller 1. The pressure contact point A1 at this time becomes the pickup point. Further, the separation pad 6 is constantly pressed against the paper feed roller 1, and this separation point is
It becomes 2.

In this state, when the paper feed roller 1 rotates in the paper feed direction C, the recording paper P on the pressure plate 4 is sent out by the paper feed roller 1, and the separation point A 2 between the paper feed roller 1 and the separation pad 6. Will be introduced. However, the number of sheets to be sent out is determined by the gap between the abutting wall 3a and the paper feed roller 1, and any further recording paper is stopped by the abutting wall 3a.

At this time, a "judgement action" is given to the leading end of the recording paper by an angle θ1 (about 20 to about 40 degrees in this case) formed between the separation pad 6 and the recording paper entry direction. Further, the paper feed roller 1 rotates, and the friction coefficient between the paper feed roller 1 and the recording paper is μ1, the friction coefficient between the recording papers is μ2, the friction coefficient between the recording paper and the separation pad 6 is μ3, Separation pad 6
If the friction coefficient is μ4, the relationship μ1>μ3> μ2 holds, so that the plurality of recording papers that have entered the separation point A2 are conveyed by the uppermost recording paper P1 by the feed roller 1, and When the recording papers are in contact only with each other, the recording papers are double-fed, but when the leading edge is loosened in a wedge shape and comes into contact with the separation pad 6, the recording paper stops there and does not double-fed. Note that the transport force is a value determined from “biasing force × the above friction coefficient” given to the separation pad 6.

The friction coefficient μ4 between the paper feed roller 1 and the separation pad 6 is set so as not to generate a frictional force larger than a drive torque of a motor or the like which is a drive source of the paper feed roller 1.

In this state, the recording paper entering the separation point A2 is separated by rotating the sheet feeding roller 1 and only one sheet is separated, and further fed by the rotation of the sheet feeding roller 1 to be fed to the nip portion of the conveying roller pair 11, 12. To reach. The recording paper that has entered the gap between the abutting wall 3a and the paper feed roller 1 does not advance beyond the separation point A2 for the above-described reason.

When the separation operation is completed, the recording sheet released by pressing the pressure plate 4 to the state shown in FIG. 4 returns to the pressure plate 4 with the remaining recording paper closed by the abutting wall 3a. become. The recording paper remaining on the separation pad 6 stops at the separation point A2. When the separated recording paper is conveyed to the printing unit by the conveyance force of the conveyance roller pairs 11 and 12, the paper feed roller 1 also stops rotating to prevent the second and subsequent recording papers from being double-fed, Only the first sheet is sent to the printing unit by the conveying roller pairs 11 and 12, and predetermined printing is performed.

[0016]

As described above, the separation and feeding are performed stably. However, even when the separated recording paper P1 enters the conveyance section and printing is performed, the recording paper P1 is kept in contact with the paper feed roller 1. Since the paper is sandwiched between the separation pads 6, a strong back tension is applied, which adversely affects the conveyance accuracy of the recording paper P1 and deteriorates the printing accuracy. for that reason,
Conventionally, a one-way clutch or the like is incorporated in the paper feed roller 1 so as to be able to hang around the recording paper being conveyed, or by providing a pair of conveyance auxiliary rollers between the paper supply roller and the conveyance roller pair, and so forth. The influence was not degraded in the transport accuracy, but could not be dealt with sufficiently.

Further, when such measures are taken, there are problems that the structure is complicated and the apparatus becomes large, and a large torque is required for the transport motor.

The present invention has been made in view of the above problems, and provides a sheet feeding apparatus capable of reducing the influence of back tension with a simple configuration without impairing the separation feeding performance. The purpose is to:

[0019]

According to the present invention, there is provided a sheet supporting means for supporting a sheet, a sheet feeding roller for feeding the sheet supported by the sheet supporting means, and a pressure contact with the sheet feeding roller. A separation pad for separating the sheets one by one, in a sheet feeding apparatus, when the sheets supported by the sheet support means are separated and fed by the separation pad by one sheet, The pressure contact between the separation pad and the paper feed roller is released, and the relative angle between the separation pad and the second and subsequent sheets is larger than the initially set angle for separation and feeding. It is characterized by changing to.

According to the present invention, after the sheet separated by the separation pad is started to be conveyed by conveying means arranged on the downstream side, the pressure contact between the separation pad and the paper feed roller is released, and , The angle is changed.

According to the present invention, the separation pad is held by a pad frame rotatably supported about a fulcrum disposed on the downstream side in the sheet feeding direction, and the pad frame is separated by a separation spring. The pad is urged so as to be pressed against the sheet feeding roller, and the upstream end of the pad holder is displaced by a cam against the urging force of the separation spring, so that the separation pad is fed to the sheet feeding roller. The pressure contact is released by separating from the roller, and the angle changes.

The present invention is characterized in that the cam rotates by a driving force from a driving source for driving the paper feed roller to displace the pad frame.

According to the present invention, there is provided a pressure contact means for pressing the sheet supported by the sheet support means by the pressure contact means and the paper feed roller, and a pressure release means for releasing the pressure contact by the pressure contact means. The pressure contact release means has a cam for moving the sheet support means against the pressure contact force of the pressure contact means, and the cam is driven by a driving force from a driving source for driving the paper feed roller. It is characterized in that the sheet support means is moved by rotation.

According to the present invention, after the end of the sheet separated by the separation means passes through the separation means, the separation pad is returned to a position for separation and feeding in which the relative angle with respect to the sheet is initially set. The sheet feeding roller reverses the sheet by a predetermined amount in the direction of returning the sheet to the upstream side, thereby returning the sheet to the initial state in which the next sheet can be separated and fed.

According to the present invention, the sheet support means supports the sheet in an inclined state such that the leading end side thereof is positioned downward, and the separation pad is arranged such that the separation surface is inclined in a direction opposite to the sheet inclination. It is characterized by.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. In addition, about the structure which is the same as or equivalent to the sheet feeding apparatus described in the prior art,
The same reference numerals are given and detailed description is omitted.

In this embodiment, the pad frame 30 holding the separation pad 6 is rotatably mounted on a fulcrum 30a provided on the downstream side in the recording paper conveyance direction, and the separation pressure is given by the separation spring 8. I have. Further, a pad arm 30b for turning is formed on the pad frame 30. An operation arm 31 for rotating the pad frame 30 is attached to the rotation support shaft 32.

The rotation support shaft 32 is a rotation shaft for transmitting the rotation to the operation arm 31. The rotation support shaft 32 is fixed by a method such as fitting by D-cut or press-fitting with a knurl so that the two rotate integrally. I have.

The drive transmission mechanism of the operation arm 31 will be described with reference to FIG.

The frame 3 is formed as a frame for supporting each mechanical element of the sheet feeding apparatus. Reference numeral 50 denotes a part of a frame constituting a transport system and the like, which is a mounting surface for mounting the sheet feeding apparatus to a recording apparatus.

A drive transmission mechanism for transmitting rotation from a drive source (not shown) to the paper feed roller 1 is disposed on the side of the frame 3. Gear 2 rotates from the drive source
The rotation drive is transmitted at 0, 21 and 22. The gear 22 is a gear that is coupled to the drive shaft 2 of the paper feed roller 1 so that rotation can be transmitted, and a cam 23 is formed integrally therewith. Reference numeral 4b denotes a pressure plate cam formed integrally with the pressure plate 4 and engaged with the cam 23 outside the frame 3.

A gear 33 meshes with the gear 21.
The gear 33 is formed with a cam 33a. Then, the rotation from the driving source is transmitted to the gear 33 via the gears 20 and 21, and the cam 33a rotates.

The rotation support shaft 32 transmits rotation to the operation arm 31 for operating the pad arm 30b of the pad frame 30. The rotation support shaft 32 and the cam 3
4 are integrally engaged, and a tip thereof is formed with a cam arm 34a. The cam 33a of the gear 33 is engageable with the cam arm 34a.
3a presses and rotates the cam arm 34a to rotate the rotation support shaft 3.
The arm 31 is rotated via 2.

The operation of the sheet feeding device will be described.

In the paper feed standby state, the cam 23 is
b, the pressure plate 4 is pressed down against the elastic force of the pressure plate spring 5, so that the pressure plate 4 is in a released state. Since the cam 22 is disengaged from the pressure plate cam 4b of the pressure plate 4, the pressure plate 4 presses the recording paper against the paper feed roller 1 by the elastic force of the pressure plate spring 5 to start the paper feeding operation. In the present embodiment, the sheet is returned to the release state again by one rotation of the sheet feeding roller 1. However, the return timing can be arbitrarily set by using a cam or by further providing a speed reduction mechanism for driving the cam.

In the separated feeding state, as shown in FIG. 1, since the operation arm 31 is not engaged with the pad arm 30b, the pad frame 30 is pressed against the paper feed roller 1 by the separation spring 8. So, as shown in FIG.
The cam 34 and the cam arm 34a are at the positions indicated by the solid lines in FIG. 3, and the cam 33a is also at the position indicated by the solid lines in FIG.

Then, the drive of the drive source is transmitted and the gear 3
3 rotates, the cam 33a moves to the cam arm 3 of the cam 34.
The cam 34 is rotated by contacting the cam 4a. As the separation feeding operation proceeds, the rotation of the gear 33 is transmitted in the direction C1 as shown in FIG. 3, the cam 33a rotates by a predetermined angle and moves to the position shown by the broken line, and the cam arm 34a moves to the position shown by the broken line. Rotate.

As a result, as shown in FIG.
1 pushes the pad arm 30b of the pad frame 30 to rotate the pad frame 30 to the standby position, so that the separation pad 6 is separated from the pressure contact position with the paper feed roller 1.

When the rotation is further transmitted, the cam 33a overruns from the position shown by the broken line in FIG. 3 and returns to the original position shown by the solid line, so that the cam arm 34a of the cam 34 becomes free. The pad frame 30 returns to the position (press-contact position) shown in FIG. 1 by the force of the time separating spring 8, and the movement of the pad arm 30b causes the arm 31 to move.
Also returns to the position shown in FIG.

At this time, the timings of the raising and lowering operation of the pressure plate 4 and the pressing and separating operations of the separation pad 6 against the paper feed roller 1 are as follows.

After the separation of the uppermost recording paper P1 by the separation pad 6, the cam 23 pushes down the pressure plate cam 4b to move the pressure plate 31 to the position indicated by the broken line in FIG. Recording paper P that was stopped
Is dropped on the pressure plate 4 to be separated from the pickup point A1. Next, the first recording paper P1 fed
When the leading end of the pad frame 30 is sandwiched between the nip portions of the transport roller pairs 11 and 12 (see FIG. 5), the pad frame 30 holding the separation pad 6 is pivotally moved downward about the fulcrum 30a on the upstream side of the transport.

As a result, the influence of the back tension generated when the uppermost recording paper P1 is sandwiched between the separation pad 6 and the paper feed roller 1 can be eliminated. At this time, since the space between the separation pad 6 and the paper feed roller 1 is opened, normally, the second and subsequent recording papers P try to fall due to their own weight generated from the stacking angle θ1, and Due to the frictional conveyance force received from the first recording sheet P1 being fed (not being pressed against the paper feed roller 1 and smaller than the frictional force at the time of separation), it falls into this gap, but as described above. To
Since the angle of the separation pad 6 is changed and the rush angle θ2 with the recording paper becomes larger than the angle θ1 suitable for separation and feeding, it stops here and does not cause double feeding.

When the end of the first recording sheet P1 has passed the separation sheet feeding point A2, the separation pad 6 is returned to the initial state in which the separation pad 6 is pressed against the sheet feeding roller 1, and then the position is changed from the solid line position to the broken line position in FIG. When the pressure plate 4 is moved up to that point, the second and subsequent recording sheets return to the separation sheet feeding point A2, so that the next recording sheet can be separated and fed.

At the time of this return operation, the leading ends of the second and subsequent sheets remaining on the separation pad 6 return to the separation point A2 because the pressure plate is opened. Further, by slightly rotating the paper feed roller 1 in the direction opposite to C, the separation point A
It is possible to reliably return the paper that has entered from 2 to the separation point A2. When the next sheet feeding operation is started in this state, the separation and feeding are repeated according to the same principle as described above.

The relationship between the cam, the arm and the position of the paper feed roller, such as the contact and separation timing, can be freely adjusted by the configuration of each gear ratio and the like.

In the present embodiment, the pressure plate 4 is
A mechanism for separating the separation pad 6 and a mechanism for separating the separation pad 6 from the paper feed roller 1 each uses the drive of the paper feed roller 1 and further uses a cam to set the timing of pressure contact / separation. However, since the timing control can be performed mechanically and easily, the cost does not increase significantly and the apparatus does not increase in size as compared with the conventional sheet feeding apparatus.

The present invention is not limited to the above-described embodiment. For example, the movement of the pressure plate and the movement of the pad are not performed by using a driving source of the sheet feeding roller but by using another driving source such as a solenoid. You may. Further, a half-moon shaped roller may be used instead of the round roller for the paper feeding roller, and rollers that freely rotate may be arranged on both sides of the half-moon shaped roller.

[0048]

According to the present invention, in this type of separation mechanism in which back tension has conventionally been a problem, the double feed can be prevented with a simple structure by changing the sheet entry angle and separating the separation pad. However, it is possible to provide a sheet feeding device with reduced back tension.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating an example of an embodiment of a sheet feeding apparatus according to the present invention.

FIG. 2 is a sectional view showing an operation state of the sheet feeding device shown in FIG. 1;

FIG. 3 is a side view showing a drive transmission mechanism of the sheet feeding device shown in FIG. 1;

FIG. 4 is a sectional view showing an example of a conventional sheet feeding apparatus.

FIG. 5 is a sectional view showing an operation state of the conventional sheet feeding apparatus shown in FIG.

FIG. 6 is a side view showing a drive transmission mechanism of the conventional sheet feeding apparatus shown in FIG.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper feed roller 2 drive shaft 3 frame 3a abutting wall 4 pressure plate (sheet support means) 4b pressure plate cam (pressure release means) 5 pressure plate spring (pressure contact means) 6 separation pad 7 pad frame 8 separation spring 23 cam (pressure release means) ) 30 pad frame 30a fulcrum 31 operating arm 32 rotation support shaft 33a cam 34 cam 34a cam arm P recording paper (sheet)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Hiroshi Yoshino 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Yasuyuki Asai 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo (72) Inventor Shinya Sonoda 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term (reference) 3F343 FA02 FB04 FC01 GA03 GB01 GC01 GD01 HB03 HD09 HD18 JA01 JD08 JD33 KB05 KB18 LA04 LA15 LC07 LC11 LC14 LC20 LC22 LD26 MA03 MA54 MB14 MC07 MC12 MC23

Claims (11)

[Claims] 1. A sheet supporting means for supporting a sheet, a sheet feeding roller for feeding a sheet supported by the sheet supporting means, and a pressure contact with the sheet feeding roller to separate the sheets one by one between the rollers. Wherein the separation pad and the paper feed roller are provided when a sheet supported by the sheet supporting means is separated and fed by the separation pad. And the relative angle between the separation pad and the second and subsequent sheets is changed so as to be larger than the initially set angle for separation and feeding. Sheet feeding device. 2. After the sheet separated by the separation pad is started to be conveyed by conveying means arranged on the downstream side, the pressure contact between the separation pad and the paper feed roller is released, and The sheet feeding device according to claim 1, wherein the angle changes. 3. The separation pad is held by a pad frame rotatably supported about a fulcrum disposed on the downstream side in the sheet feeding direction, and the pad frame is separated by a separation spring. The separation pad is urged to be pressed against the paper feed roller, and the separation pad is displaced from the paper feed roller by displacing the upstream end of the pad holder by a cam against the urging force of the separation spring. 3. The sheet feeding apparatus according to claim 2, wherein the pressure is released by separating the sheet and the angle is changed. 4. The sheet feeding device according to claim 3, wherein the cam is rotated by a driving force from a driving source that drives the paper feed roller to displace the pad frame. 5. A pressing means for pressing the sheet supported by the sheet supporting means and the sheet feed roller by the pressing means, and a pressing release means for releasing the pressing by the pressing means. The pressure releasing means has a cam for moving the sheet supporting means against the pressing force of the pressing means, and the cam is rotated by a driving force from a driving source for driving the sheet feeding roller. 5. The sheet feeding apparatus according to claim 4, wherein the sheet supporting means is moved by moving. 6. After the end of the sheet separated by the separation means has passed through the separation means, the separation pad is returned to a position for separation and feeding in which a relative angle with respect to the sheet is initially set, 3. The sheet feeding apparatus according to claim 1, wherein the sheet feeding roller reverses the sheet by a predetermined amount in a direction of returning the sheet to the upstream side, thereby returning the sheet to an initial state in which the next sheet can be separated and fed. 7. The sheet supporting means supports the sheet in an inclined state such that the leading end side thereof is positioned downward, and the separation pad is arranged so that the separation surface is inclined in a direction opposite to the sheet inclination. The sheet feeding device according to any one of claims 1 to 6, wherein 8. A sheet feeding apparatus according to claim 1, further comprising: a recording unit that records on a sheet sent from the sheet feeding apparatus. Recording device. 9. A sheet supported by sheet supporting means and pressed out by a paper feed roller is sent out by rotating the paper feed roller, and the fed out sheet is separated one by one by a separation pad pressed into contact with the paper feed roller. When the separated sheet is fed by the feed roller and the separation pad,
The press-contact between the fed sheet and the paper feed roller is released, and after the fed sheet is started to be conveyed by conveying means arranged downstream of the separating means, the separation pad and the paper feed roller are separated. Releasing the pressure contact with the roller and changing the relative angle between the separation pad and the second and subsequent sheets so as to increase from the initially set angle for separation and feeding. Paper feeding method of the feeding device. 10. The separation pad, the angle of which has changed after the trailing edge of the separated sheet has passed between the paper feed roller and the separation pad, is returned to an initial position. 3. The sheet feeding method of the sheet feeding device according to 1. 11. The sheet feeding apparatus according to claim 10, wherein when the separation pad is returned to an initial state, the sheet feeding roller is rotated in the reverse direction to return the remaining sheet to the sheet supporting means. The paper feeding method of the device.