JPH1191971A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of a fluctuation in the press load of a handling roller according to the rotation direction of the handling roller of a paper feeding device and to effect a stable feed of sheet papers. SOLUTION: A paper feeding device is formed such that at least one paper sheet (p) of stacked paper sheets (p) is fed by a delivering means 1, one paper sheet (p) is separated by a separating means and fed. The separating means comprises a feed roller 2 driven for forward rotation; a handling roller 3 to be driven for reversing and brought into pressure contact against the feed roller 2 through the paper sheet; a torque limiter 6 arranged on the rotary shaft of a handling roller 3; and a press means 16 arranged at the handling roller having a press force directing in a range in a 15 deg. arc or less based on a direction to interconnect the center of the handlirag roller 3 and the rotation center of the feed roller 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeder for sheet-like recording paper in an image forming apparatus such as a copying machine, a facsimile, a printer, and the like, and a document feeder in an automatic document feeder attached to an image reading apparatus. It relates to a paper device.

[0002]

2. Description of the Related Art Conventionally, in an apparatus such as a copying machine, a facsimile, a printer, or the like, sheets of paper stacked on a paper tray, a paper cassette, a paper stacker, etc. are sequentially taken out one by one from the top or bottom. And a paper feeding device for feeding the image to the image recording unit and the like.

In general, this type of sheet feeding apparatus is disclosed in Japanese Patent Application Laid-Open Nos. Sho 62-105834 and 63-574.
As shown in JP-A-47-47, a feed roller and a separating roller are provided in front of a feeding roller in pressure contact with each other, and the fed sheet-like paper is separated by being inserted between the feed roller and the separating roller. The paper is fed one by one.

FIG. 6 is a cross-sectional view of a conventional separating roller type sheet feeder. In the paper feeding process, first, the upper surface of the paper p stacked on the movable bottom plate 22 rises to a set position by the swing of the lever 21, and the pickup roller 1 and the feed roller 2 start rotating by the paper feed signal. Predetermined pressure P1
The pickup roller 1 brought into pressure contact with the upper surface of the sheet by the sheet feeding roller 2 separates the sheet p from the feed roller 2 (reverse roller).
After being fed to the nip position with No. 3, it is released from the paper surface. The separation roller 3 is driven in the direction opposite to the traveling direction of the paper p via the torque limiter 6, and
Is pressed against the feed roller 2 with an initial pressure of When the separating roller 3 comes into direct contact with the feed roller 2 (when there is no paper p between the nips) or when the paper p is fed between the single nips, the torque limiter 6 slips beyond the limit torque and the feed roller 2 Followed rotation.
However, when two or more sheets of paper p are fed between the nips, the limit torque overcomes the frictional force between the sheets and causes the separating roller 3 to rotate in the reverse direction to push back the lower sheet of paper p to prevent multiple sheets from being fed. I have.

[0005] Such a paper feeder will be described with reference to the examples shown in Figs. FIG. 7 is a perspective view of the sheet feeding device, and FIG.
FIG. 8A is a plan view of a double feed prevention unit of the sheet feeding device, and FIG.
FIG. 2 is a front view of the sheet feeding device.

In a conventional paper feeder, as shown in these figures, a pickup roller 1 is provided in a state of being pressed against a sheet p deposited on a sheet tray, and By rotation, paper p
Is sent out.

Following the pickup roller 1, there is provided a sheet separating mechanism in which a feed roller 2 and a separating roller 3 are provided to face each other. A mechanism is provided for sending out only the top one sheet of the sheets, and stopping or returning the sheet p below it.

This system is generally called a friction separation roller system, and is used in many paper feeders.

In the above-described paper separating mechanism, the feed roller 2 is driven and rotated integrally with the drive shaft 4 from a drive source (not shown) via gears Z1 and Z2. Handling roller 3
Are connected to a gear Z7 fixed to a torque limiter shaft 7 having a torque limiter 6. The support shaft 5 is rotatably supported by a pressure arm member (support) 9. The pressing arm member 9 is spring-biased by a pressing spring (spring member) 8 provided between the pressing arm member 9 and a fixed portion of a frame of a copying machine or the like so that the separating roller 3 is pressed against the feed roller 2. It is composed.

The gear Z7 is connected to a gear Z5 via an intermediate gear Z6.
Connected to The other end of the shaft 10 of the gear Z5 is provided with a gear Z4.
Are integrated and connected to the gear Z2 via the intermediate two-stage gears Z3B and Z3A. With these gear trains,
Power is transmitted from the drive source to the torque limiter shaft 7 via the gears Z1 and Z2.

In the paper feeding process of the paper feeding device, first, the upper surface position of the paper p rises to the set position, and the pickup roller 1 and the feed roller 2 start rotating by the paper feed signal. The pickup roller 1 pressed against the upper surface of the paper at a predetermined pressure is
After the paper p is fed to the nip position between the feed roller 2 and the separating roller 3, the paper p is released from the paper surface.

The separating roller 3 is provided with the gear trains Z2 and Z3.
(A, B), Z4, Z5, Z6, Z7 and the torque limiter 6 are driven in the opposite direction to the traveling direction of the paper p, and the pressing force of the spring 8 of the pressure arm 9 and the torque limiter 6 It is pressed against the feed roller 2 with the operating pressure generated by the torque. The separation roller 3 is a feed roller 2
When there is direct contact with (when there is no paper between the nips)
Alternatively, when the sheet p is fed between the nips, the torque limiter 6 slips beyond the limit torque and is rotated by the feed roller 2. However, when two or more sheets of paper p are fed between the nips, the limit torque overcomes the frictional force between the sheets, rotates the separating roller 3 in the reverse direction, and pushes back the lower sheet to perform the double feed (multiple sheet feed). Preventing. In FIGS. 6 to 8, solid arrows shown on each rotating body indicate the rotation direction when the sheets are not multi-fed, and broken lines indicate the rotation directions when the sheets are multi-fed.

As shown in FIG. 8B, the pressing force of the separating roller 3 against the feed roller 2 is applied via a swing fulcrum shaft 10 of a pressing arm 9 which supports the separating roller 3 in a swingable manner. It depends on the pressing force of the spring 8. The position of the swing fulcrum shaft 10 is usually set to avoid the conveyance path of the paper p.
For example, the position is set to the position shown in FIG.

The driving force of the separating roller 3 is transmitted from a driving source via a gear train. In the double feed prevention device of the separating roller type, a torque limiter 6 is generally connected in the middle of a drive transmission system. Due to the magnitude of the force acting on the separating roller 3 via the sheet p and the force of the torque limiter 6, the forward and reverse rotation directions of the separating roller 3 change, and this action prevents the sheet p from being double fed. . The driving force is transmitted as a force for rotating the separating roller 3 in the direction opposite to the direction in which the sheet p is transported.

[0015]

When the pivoting fulcrum shaft 10 shown in FIG. 8 (b) is set and the separating roller 3 rotates following the direction of transport of the paper p, that is, the torque limiter 6 is rotated. When the separating roller 3 rotates against the rotation of the roller, the limit torque of the torque limiter 6 acts as a pressing force of the separating roller 3 to the feed roller 2 due to the relationship between the fulcrum, the point of action, and the direction of the force.

When the lower sheet p2, which has been multi-fed from the feed roller 1, is conveyed in a direction opposite to the normal conveying direction and the multi-feed is corrected and separated, the torque limiter 6 is inputted without slipping. When the separating roller 3 rotates in the direction of the force, the torque limiter 6 acts as a connecting member, and no limit torque is generated.
Is only the load by the pressure spring 8.

As described above, the contact pressure between the feed roller 2 and the sheet P to be conveyed fluctuates depending on the rotation direction of the separating roller 3, and the frictional force between the separating roller 3 and the sheet P also fluctuates. Sex becomes unstable.

[0018]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the conventional paper feeder, eliminates fluctuations in the pressing load of the separation roller due to the rotation direction of the separation roller, and achieves stable paper feeding. The purpose is to realize.

A paper feeder according to the present invention that achieves the above object,
In a sheet feeding device for feeding at least one sheet out of the stacked sheets by a feeding unit and separating and feeding one sheet by a separating unit, the separating unit includes a feed roller driven in a forward rotation. A separating roller which is driven in reverse rotation and presses against the feed roller via the sheet, and a torque limiter provided on a rotation shaft of the separating roller, and wherein the separating roller is disposed at a center of the separating roller. 15 each for the direction connecting the rotation centers of
A pressing means whose pressing force is directed within a range of less than ° is provided.

Further, according to the present invention, which achieves the above object, at least one sheet out of the stacked sheets is
In a paper feeder which feeds out one sheet by a feeding means and separates and feeds one sheet by a separating means, the separating means includes a feed roller driven in a forward rotation and a feed roller driven in a reverse direction through the sheet. A separating roller that presses the separating roller, a torque limiter provided on a rotation shaft of the separating roller, and a pressing arm member and a spring member that swingably support the separating roller. And a pressing means for pressing the pressing arm member toward the center of the pressing arm member.

B / (r · a) <3.0 × 10 ⁻² (1 / mm) Preferably, b / (r · a) <1.5 × 10 ⁻² (1 / mm) The distance in the direction perpendicular to the line connecting the center of the separation roller and the center of the feed roller between the swinging fulcrum axis of the pressure arm member and the rotation axis of the separation roller, b is the pressure contact position between the separation roller and the feed roller, and the position of the pressure arm member. The distance r in the direction parallel to the line connecting the center of the separation roller with the pivot point and the center of the feed roller, and r is the radius of the separation roller.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a paper feeder according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall configuration diagram of an image forming apparatus provided with an automatic document feeder DF.

The image forming apparatus main body includes an image reading unit A,
An image forming section B, an image processing section C, an image writing section D, a cassette sheet feeding section E, a manual sheet feeding section F, an automatic double-sided copy sheet feeding section (ADU) G, and a large capacity sheet feeding section (LCT) H are provided. ing.

The above-described apparatus and sheet feeding section are provided with a separating means (a separating roller type double feeding prevention apparatus) as shown. That is, the automatic document feeder DF has the document sheet separating means K1, the cassette sheet feeding section E has the sheet separating means K2 and K3, the manual sheet feeding section F has the sheet separating means K4, and the automatic double-sided copy sheet feeding section G has the sheet separating means. K5, paper separation means K6, K
7 are provided. Each of these separating means has substantially the same structure.

FIG. 2 is a perspective view showing an embodiment of the paper feeding apparatus of the present invention. In addition, about the code | symbol used for a figure, the part which has the same function as FIGS. 6-8 is attached | subjected.

In this embodiment, a torque limiter shaft 7 is provided on a support shaft of the separating roller 3, and the torque limiter 6 and the torsion coil spring 11 are mounted on the torque limiter shaft 7.
Was provided. The torsion coil spring 11 is wound around the outer periphery of the torque limiter shaft 7, one end of which is locked by a fixing pin 12 driven into the torque limiter shaft 7, and the other end is fixed by a fixing pin 13 driven into an end face of the torque limiter 6.
It is locked to. The torsion coil spring 11 is twisted and accumulates torsional force (torsion) when the separating roller 3 rotates forward in the direction of the solid arrow shown in the figure. The torsional force accumulated in the torsion coil spring 11 gives the separating roller 3 a reverse rotation driving force.

In the normal paper feeding process, the torsion coil spring 11 is twisted and the limit torque is accumulated until the separating roller 3 rotates in the direction indicated by the solid line in the drawing and the torque limiter 6 idles at the limit torque. .

Next, when the multi-fed paper p is fed, the limit torque overcomes the frictional force between the papers, and the torsion of the torsion coil spring 11 is released. The separating roller 3 rotates reversely in the direction indicated by the dashed arrow. Thus, by the forward rotation of the feed roller 2 and the reverse rotation of the separating roller 3, only the uppermost sheet p in contact with the feed roller 2 is fed through the nip position between the feed roller 2 and the separating roller 3, The lower sheet is pushed back by the separating roller 3 to prevent double feeding.

The torque limiter shaft 7 penetrates an elongated guide hole 14B formed in an upright side wall 14A near both ends of the frame 14, and is slidable in the vertical direction.

Fixing pins 15 are penetrated and implanted near the shaft ends of the torque limiter shaft 7, respectively. One end of the fixing pin 15 projects below the torque limiter shaft 7,
Elastically compressible coil spring (compression spring member) 16
To loosely fit into the inner diameter of the coil spring 16 to position the coil spring 16. The upper end surface of the coil spring 16 positioned by the fixing pin 15 is pressed against the outer peripheral surface of the torque limiter shaft 7, and the lower end surface of the coil spring 16 is
The coil spring 16 (pressing means) pushes up the torque limiter shaft 7 vertically upward. The torque limiter shaft 7 urged by the coil spring 16 urges the separating roller 3 to press the feed roller 2 rotatably supported at a fixed position with a predetermined pressing force.

FIG. 3 is a front view showing another embodiment of the paper feeding apparatus of the present invention.

The support shaft 5 on the shaft of the separating roller 3 is supported by a guide hole 17A of the movable frame 17, and the movable frame 17 is urged upward by a coil spring 16 so that the separating roller 3 is fed to the feed roller. 2 was pressed.

The separating roller 3 which is in pressure contact with the feed roller 2 is not limited to a vertically upward direction.
In the range of 15 ° to the left and right with respect to the vertical line of the pressure contact position of 6, the fluctuation of the pressing load of the separating roller 3 due to the rotation direction of the separating roller 3 can be eliminated, and stable paper separation and conveyance can be realized. it can.

FIG. 4 is a front view showing still another embodiment of the sheet feeding device of the present invention.

A swing fulcrum shaft 10 for swingably supporting the pressure arm member 9 is disposed obliquely below the downstream side in the transport direction of the sheet p. That is, the swing fulcrum shaft 10 is disposed at a distance a in the paper transport direction and a distance b in a direction perpendicular to the paper transport direction with reference to the axis of the support shaft 5 of the separating roller 3 and the axis of the torque limiter shaft 7. ing.

When the following experimental device was used, the position of the swing fulcrum shaft 10 was a = 27.75 mm and b = 21.60 m.
m, radius r of separation roller 3 = 12 mm, capacity of torque limiter T = 628 g · f · cm, b / (r · a) = 6.
5 × 10 ⁻² (1 / mm), and when the separating roller 3 rotates following the paper conveyance direction, the pressing force P excluding the pressing force by the pressure spring (spring member) 8 generated in the separating roller 3. _T was P _T = 407.4 g · f.

The pressing force when the separating roller 3 is rotating in the direction opposite to the normal conveying direction of the sheet is only the pressing force by the spring member 8.

As described above, the pressing force of the separating roller 3 against the feed roller 2 changes depending on the rotation direction of the separating roller 3. That is, when the paper p is rotated in the paper transport direction following the paper p, it is close to the double feed area shown in FIG. 5, and when the separating roller 3 is rotated in the opposite direction to the paper transport direction, the paper cannot be fed. Close to the area.

This narrows the proper range of the pressing load by the spring member 8 of the separating roller 3 for preventing the double feeding of the paper p and enabling the paper feeding. When separating and feeding various papers having different friction coefficients, This is a major cause of paper feeding failure.

FIG. 5 is a characteristic diagram showing the relationship between the pressing load of the separating roller 3 and the frictional force acting on the sheet.

Actually, the coefficient of friction μ2 between the sheets fluctuates depending on the type and environment (temperature and humidity) of the sheet p, and the same applies to the coefficient of friction μ1 between the sheet p and the separating roller 3.
The pressing load of the separating roller 3 must have a sufficient margin with respect to the boundaries M and N shown in FIG. However, a margin cannot be secured because of an increase by P _T , and as a result, depending on conditions, two or more sheets may be overlapped or a sheet feeding failure may occur.

In the present invention, in FIG.
By setting the position of the swing fulcrum of the pressure arm member 9 within the following range, the pressing load of the separating roller 3 is set to a value that allows a sufficient margin.

By setting a, b, and r in the following ranges using an experimental apparatus, the pressing force P generated on the separation roller 3 is set.
_T is 188.4 g · f and 94.2 g · f, which is a value that allows a sufficient margin.

B / (r · a) <3.0 × 10 ⁻² (1 / mm) preferably b / (r · a) <1.5 × 10 ⁻² (1 / mm) where a is loose Swing fulcrum shaft 1 with roller 3 as reference position
0 is the distance in the direction perpendicular to the line connecting the center of the separation roller 3 and the center of the feed roller 2, and b is the center of the separation roller 3 of the swing fulcrum shaft 10 with the separation roller 3 as a reference position and the center of the feed roller 2. And r is the radius of the reverse roller. In this experiment, the appropriate range of the pressing load by the separating roller 3 (the range between M and N in FIG. 5).
Is about 350 to 880 g · f, and the increase _PT of the pressing load of the separating roller 3 is 188.4 g · f to 94.2 g.
There is no problem if the value is within the range of f. Accordingly, the range of variation of the pressing load of the separating roller 3 depending on the position of the pivoting fulcrum shaft 10 of the pressing arm member 9 is reduced to such an extent as not to hinder the sheet feeding, and stable sheet feeding is achieved.

The paper feeder of the present invention is not only effective when applied to the various paper feed units shown in FIG. 1, but also as a means for preventing double feed in a general friction separation roller type paper feeder in a facsimile or printer. Applicable.

[0047]

Since the paper feeder of the present invention has the above-described configuration, fluctuations in the pressing load of the separation roller against the paper due to the rotation direction of the separation roller are eliminated.
Fluctuations in the frictional force with the paper were also eliminated, and stable paper feed was achieved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an image forming apparatus including an automatic document feeder DF.

FIG. 2 is a perspective view showing an embodiment of the sheet feeding device of the present invention.

FIG. 3 is a front view showing another embodiment of the sheet feeding device of the present invention.

FIG. 4 is a front view showing still another embodiment of the sheet feeding device of the present invention.

FIG. 5 is a characteristic diagram showing a relationship between a pressing load of a separating roller and a frictional force acting on a sheet.

FIG. 6 is a cross-sectional view of a conventional separating roller type sheet feeding device.

FIG. 7 is a perspective view of a main part of a conventional sheet feeding device.

FIG. 8 is a plan view and a front view of a double feed prevention unit of a conventional sheet feeding device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pickup roller (delivery means) 2 Feed roller 3 Separation roller (reverse roller) 5 Support shaft 6 Torque limiter 7 Torque limiter shaft 8 Pressure spring (spring member) 9 Pressure arm member (support) 10 Oscillating fulcrum shaft 11 Torsion coil spring 16 Coil spring (compression spring member, pressing means) 17 Movable frame body K1 to K7 Paper separation means

Claims (2)

[Claims] 1. A sheet feeding device for feeding at least one sheet out of stacked sheets by a feeding unit and separating and feeding one sheet by a separating unit, wherein the separating unit is driven by a forward rotation drive. A feed roller, a separating roller driven in reverse rotation and pressed against the feed roller via the sheet, and a torque limiter provided on a rotation shaft of the separating roller, and the separating roller A sheet feeder, comprising: a pressing unit having a pressing force directed within a range of 15 degrees or less with respect to a direction connecting the center of rotation of the feed roller from the center. 2. A sheet feeding device for feeding at least one sheet out of the stacked sheets by a feeding unit and separating and feeding one sheet by a separating unit, wherein the separating unit is driven by a forward rotation drive. Feed roller, a separating roller driven in reverse rotation and pressed against the feed roller via the paper, a torque limiter provided on a rotation shaft of the separating roller, and a pressurizing support for swingably supporting the separating roller. Pressing means for pressing the separating roller toward the center of rotation of the feed roller by an arm member and a spring member, and setting a position of a swing fulcrum of the pressing arm member within the following range. A sheet feeding device characterized by the following. b / (r · a) <3.0 × 10 ⁻² (1 / mm) preferably b / (r · a) <1.5 × 10 ⁻² (1 / mm) where a is a pressure arm member Distance in the direction perpendicular to the line connecting the center of the separation roller and the center of the feed roller between the pivot shaft of the separation roller and the rotation axis of the separation roller, b is the pressure contact position between the separation roller and the feed roller, and the rotation support point of the pressure arm member Is the distance in the direction parallel to the line connecting the center of the separating roller and the center of the feed roller, and r is the radius of the separating roller.