JP2000168982A - Paper sheet feeder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent double feed even in any combination of conditions irrespective of a sheet size and paper quality. SOLUTION: Pressing force between a hopper 3b for mounting stacked paper sheets and a pick-up roller 6 for feeding the paper sheets, and pressing force between a separation roller 7 for preventing double feed and a retard roller 8 are made to be regulated respectively at the same time. By this constitution, the sheet from the hopper 3b is fed as a single sheet, double feed by the separation roller 7 and the retard roller 8 is regulated, and sheet feed is optimized in a path ranging from a hopper 3b side to double feed separation to prevent the double feed.

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 in an image reading device such as an image scanner, for example.
In particular, the present invention relates to a paper feeding device capable of adjusting a paper feeding / separation performance to reliably prevent double feeding even when a document size and paper quality are variously changed.

[0002]

2. Description of the Related Art An image reading apparatus such as an image scanner is provided with a paper feeding device for feeding a sheet set on a hopper to a line. This sheet feeder feeds out stacked sheets one by one from the top, and most of the sheet feeders have a double feed prevention mechanism in which two or more sheets are sent out by friction between overlapping sheets. A paper feeder having such a double feed prevention mechanism is disclosed in, for example, Japanese Patent Application Laid-Open No. 4-286558.

FIG. 7 is a schematic diagram showing a typical example of a conventional double feed prevention mechanism, and the one disclosed in the above-mentioned publication has almost the same configuration.

In FIG. 7, a hopper 5 for mounting and setting paper P such as an original to be read or various documents is set.
Reference numeral 1 is arranged at the base end of the reading line, and a pickup roller 52 for rotating the sheet P by contact with the surface of the uppermost sheet P and feeding out the sheet P by frictional force is arranged. The hopper 51 is urged toward the pickup roller 52 by a spring 51a, and presses the sheet P against the pickup roller 52 so that only the top sheet P can be fed out by friction with its peripheral surface. Further, the pressing force against the pickup roller 52 is kept substantially constant by the spring 51a even when the thickness of the stacked sheets P changes.

In the line on the output side of the hopper 51, for example, three-stage conveying rollers 53, 54 and 55 for feeding the paper P to the image reading position are arranged, and the paper P fed from the hopper 51 is nipped. And transport it downstream while pulling it out. A separation roller 56 and a retard roller 57 are provided between the hopper 51 and the first-stage transport roller 53 as a mechanism for preventing double feeding of the paper P.

The prevention of double feeding by the separation roller 56 and the retard roller 57 is widely known in the field of an image reading apparatus, a copying apparatus and the like.
Is a motor in which a torque limiter 57b is interposed around a main shaft 57a rotated in a direction indicated by an arrow in the drawing by a drive motor (not shown). That is, by providing the torque limiter 57b, when one sheet P is fed out from the pickup roller 52, the retard roller 57 receives the rotational torque of the separation roller 56 and rotates in the transport direction of the sheet P. Then, when two sheets of paper P are double-fed and nipped, the retard roller 57 keeps rotating in the direction of the arrow, and pushes the double-fed lower paper P back to the hopper 51 side.

[0007]

The size of the original paper P to be placed on the hopper 51 is various. For example, the size of the original paper P is such that the maximum size is A3 size and the minimum size is B5 size or smaller. It is necessary to As described above, when the size of the sheet P is set to be the same, the weight applied to the hopper 51 is large when the size of the sheet P is the same, and the weight load is small when the size is small. On the other hand, the spring 5
Since the spring constant of 1a is fixed, when the size of the sheet P is large, the pressing force on the pickup roller 52 is weak because the weight load is large, and the pressing force is strong as the size of the sheet P is small.

As described above, even when the pressing force applied to the pickup roller 52 changes depending on the size of the sheet P, the sheet P itself cannot be fed unless a proper frictional force with the pickup roller 52 is obtained. For this reason,
Even when the largest size paper P is placed on the maximum number of hoppers 51, the spring constant of the spring 51a must be set so that the frictional force required for feeding between the paper P and the pickup roller 52 can be secured.

However, when the size of the paper P is large, the setting of the spring constant of the spring 51a as described above
Feeding using friction between the pickup roller 52 and the peripheral surface is possible, but when the size of the sheet P is small, the weight load is small, and the urging force of the spring 51a is too strong. Therefore, the pickup roller 5
2 also increases the reaction force against the sheet P, and a large frictional force acts not only on the uppermost sheet P but also on the sheet below the sheet P, so that multiple feeds of the sheets P are likely to occur.

On the other hand, even if the paper P is multi-fed, it is blocked by the separation roller 56 and the retard roller 57 disposed in the immediate vicinity of the hopper 51, and the retard roller 57 I should push it back.
However, if the pressing force of the pickup roller 52 against the sheet P exceeds the return force of the retard roller 57 due to strong pressing by the spring 51a, the multi-fed sheet cannot be returned. For this reason, the lower-side sheet P that is being multi-fed is pressed in the sheet feeding direction by the pickup roller 52 and, at the same time, receives a reverse return force by the retard roller 57. Therefore, the paper P is jammed between the pickup roller 52 and the retard roller 57, and the paper P cannot be fed out.

Further, when the sheets P are in a multi-feed state, it is a necessary condition for the separation of the sheets P that the critical set torque of the torque limiter 57b be large with respect to the sliding friction force between the sheets P. For example, when the sliding frictional force between the papers P exceeds the critical set torque of the torque limiter 57b, particularly when the papers P are coarse and the sliding friction coefficient is large, the retard roller 57 rotates in the paper feeding direction. , And the sheet P cannot be separated, and a double feed occurs.

Further, when the position of the retard roller 57 is fixed with respect to the separation roller 56, the pressing force on the sheet P passing therebetween is substantially constant. And
The frictional force between the contact surfaces of the overlapping sheets P during the double feeding is substantially proportional to the magnitude of the pressing force by the separation roller 56 and the retard roller 57. Therefore, for example, under the condition that the paper quality of the paper P is coarse and the pressing force is strong, the sliding friction force between the papers P easily exceeds the critical set torque of the torque limiter 57b, resulting in the occurrence of double feeding.

As described above, the double feeding of the paper P occurs when the pressing force against the pickup roller 52 and the nip force between the separation roller 56 and the retard roller 57 with respect to the paper P are both inappropriate. I do. The possibility of causing double feed is also high enough due to the mutual relationship between the pressing force and the nip force.
Unless both the pressing of the sheet P against the sheet 2 and the nip force between the separation roller 56 and the retard roller 57 are optimized, the cause of the double feeding of the sheet P will not be eliminated.

An object of the present invention is to provide a paper feeder which can prevent double feed more reliably regardless of the size and quality of paper, regardless of the combination of conditions.

[0015]

According to a first aspect of the present invention, there is provided a paper feeder comprising: a pickup roller disposed at a start end of a line of paper to be fed; and a pickup roller disposed below the pickup roller and stacked on the upper surface thereof. A hopper that can be moved in a direction in which the surface of the uppermost layer abuts against the peripheral surface of the pickup roller, and separation rollers for preventing double feed that are respectively arranged downstream of the pickup roller and above and below the paper pass line. And a retard roller. The pressing force between the hopper and the pick-up roller and the pressing force between the separation roller and the retard roller are controlled by the conditions for single-sheet feeding of the sheet and two or more sheets. The relationship can be set to satisfy the conditions of the double feed regulation.

Further, there is provided a pressing force adjusting means for adjusting a pressing force between the hopper and the pickup roller and a pressing force between the separating roller and the retard roller, respectively. , And the double feed can be restricted.

[0017]

According to the first aspect of the present invention, there is provided a pickup roller disposed at a start end of a line of a sheet to be fed, and a pickup roller disposed below the pickup roller and stacked and mounted on an upper surface thereof. A hopper that can be moved in a direction in which the surface of the upper layer abuts against the peripheral surface of the pickup roller, and separation rollers for preventing double feed that are respectively arranged downstream of the pickup roller and above and below the paper pass line. A retard roller; and a pressing force between the hopper and the pickup roller and a pressing force between the separation roller and the retard roller, respectively. This is a paper feeder that can be set so as to satisfy the conditions of the double feed regulation, and even if the size and quality of the paper loaded on the Having a pressing force by appropriately adjusting, effect of preventing the double feeding of the sheet between the pressing force and the separating roller and the retard roller between the click-up roller.

According to a second aspect of the present invention, there is provided a pickup roller disposed at a start end of a line of a sheet to be fed, and a surface of the uppermost layer of the sheets disposed below the pickup roller and stacked on the upper surface thereof. A hopper operable to move in a direction of abutting against a peripheral surface of the pickup roller, and a separation roller and a retard roller for preventing double feed, which are respectively disposed downstream of the pickup roller and above and below a path line of the sheet. And a pressing force adjusting means for adjusting a pressing force between the hopper and the pickup roller and a pressing force between the separation roller and the retard roller, and is mounted on the hopper. Even if the paper size and paper quality are various, the pressing force adjustment means can be used to feed the cut sheet from the hopper and to the separation roller and the retard roller. An effect that can be adjusted depending on various types of sheets to allow multi-feed preventing that.

According to a third aspect of the present invention, the pressing force adjusting means controls the pressing force between the hopper and the pickup roller and the pressing force between the separation roller and the retard roller, respectively, of the paper. 3. The paper feeder according to claim 2, wherein the conditions satisfying the condition of the cut sheet feeding and the condition of the double feed control of two or more sheets can be simultaneously set, and the size and the quality of the paper mounted on the hopper are various. Even in this case, by appropriately adjusting the pressing force between the hopper and the pickup roller and the pressing force between the separation roller and the retard roller, there is an effect that double feeding of paper is prevented.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is an external view of an image scanner provided with the sheet feeding device of the present invention.

Referring to FIG. 1, an image scanner includes a housing 1 provided with an operation section 1a standing upright on the right side when viewed from the front, and a sub-housing 2 located on the left side of the operation section 1a and connected to open and close vertically. And a paper feed unit 3 for mounting a document such as a sheet on the front side of the housing 1 and below the sub-housing 2. The housing 1 and the sub-housing 2 are provided with a paper transport mechanism and an image reading device using an optical system. After reading an image from the paper fed from the paper feeding unit 3, a collection tray 2 a formed on the upper surface of the sub-housing 2 is provided.
The paper is ejected.

The paper feed unit 3 includes a frame 3a fixed to the housing 1 and a hopper 3b contained in the frame 3a for mounting paper. The hopper 3b has a size corresponding to the size of the paper. And a pair of side guides 3c for changing the distance between them. The hopper 3b is rotatably connected to the frame 3a at both ends on the distal end side by pins 3d so that the hopper 3b can rotate vertically with the base end side as a free end. That is,
The frame 3a is kept in the fixed position shown in FIG. 1 with respect to the housing 1, and in this frame 3a, the hopper 3b is assembled to the housing 1 so that its base end can freely move up and down. You.

FIG. 2 is a longitudinal sectional view of a main part showing a connection structure of the hopper 3b to the housing 1 side together with a pickup roller and a double feed prevention mechanism. FIG. 3 is a main part of FIG. 2 except for a separation roller. It is a top view.

Two arms 5 are rotatably mounted around a first support shaft 4a fixed in the housing 1, and are attached to a holding shaft 5a connecting the ends of these arms 5 to each other. A support roller 5b for receiving the bottom surface on the base end side of the hopper 3b is rotatably mounted. On the other hand, the tip of the hopper 3b is connected to the frame 3a via a pin 3d so as to be freely rotatable in the vertical direction. Therefore, when the arm 5 is rotated from the position indicated by the dashed line in FIG. 2 to the position indicated by the solid line, the support roller 5b receiving the base end of the hopper 3b lifts the hopper 3b while rotating. When the arm 5 is turned in the counterclockwise direction, the base end of the hopper 3b is lowered, and the posture of the hopper 3b is set to a position indicated by a dashed line in the figure.

In the sub-housing 2, a pickup roller 6 is disposed at a position covering the upper surface on the base end side of the hopper 3b, and a separation roller 7 is provided at a position slightly away from the hopper 3b. The pickup roller 6 and the separation roller 7 are arranged one by one at the center in the width direction of the hopper 3b, and the drive shaft 7a passing through the separation roller 7 is connected to the output shaft of a drive motor (not shown). . A drive system is connected between the separation roller 7 and the pickup roller 6 by, for example, a gear train, and the separation roller 7 and the pickup roller 6 rotate at the same peripheral speed.

Further, a hopper 3b is provided below the separation roller 7.
A retard roller 8 for preventing double feed is disposed below the pass line of the paper fed from the printer. The retard roller 8 is provided with a torque limiter. As is well known in the art, when the torque is below the critical set torque of the torque limiter, that is, when there is a double feed of the paper, the retard roller 8 pushes the paper back to the hopper 3b side. The rotation is continued, and when a load equal to or greater than the critical set torque is applied without the double feed of paper, the paper rotates in the reverse direction in the paper feeding direction.

Here, the hopper 3b is provided so that the uppermost layer of the paper mounted thereon comes into contact with the pickup roller 6 and is fed out by the frictional force, so that the first support shaft 4a and the arm 5 are moved. Between torsion spring 9
Intervene. The torsion spring 9 utilizes a torsion coil spring.

As shown in FIG. 2, the torsion spring 9 has two hooks 9a and 9b projecting tangentially from the circumferential surface of the helical winding at both ends in the winding direction. Engaging hole 5c provided with arm 9a in arm 5
And the hook 9b at the other end is a free end.
A hopper cam 10 for adjusting the elastic biasing force of the torsion spring 9 is arranged in contact with the hook 9b at the free end.

The hopper cam 10 is fixed to an adjusting shaft 11 extending in the width direction of the housing 1. An adjusting dial 11a is attached to one end of the adjusting shaft 11 as shown in FIG. It is facing. As shown in FIG. 2, the outer periphery of the hopper cam 10 has a circular shape eccentric to the adjustment shaft 11, and presses the hook 9 b in a direction in which the hook 9 b is tightened in the winding direction of the torsion spring 9.
Then, by turning the adjustment dial 11a, the hook 9b
The position of the peripheral surface of the hopper cam 10 that abuts on the torsion spring 9 is changed, thereby adjusting the degree of tightening of the torsion spring 9 in the winding direction.

On the other hand, an operating shaft 5d for pushing down the arm 5 in response to the upward rotation of the arm 5 by the torsion spring 9 is provided in the housing 1. The operation shaft 5d is arranged as an axis parallel to the first support shaft 4a and is rotatable by a drive motor (not shown) arranged inside the housing 1. As shown in FIG. 3, disc-shaped flanges 5e are provided at both ends of the operation shaft 5d in the axial direction, respectively, so as to face the pair of arms 5, respectively. And a boss 5f that abuts on the upper surface of the boss.

By providing such an operation shaft 5d, the boss 5f indicated by a solid line in FIG. 2 is separated from the upper surface of the arm 5, and there is no downward restriction of the arm 5, so that the arm 5 is not restricted.
The drum 5 is rotated clockwise around the first support shaft 4 a by the urging force of the torsion spring 9 to bring the upper surface of the base end of the hopper 3 b closest to the pickup roller 6. On the other hand, when the operation shaft 5d is rotated by the drive motor, the boss 5f
Comes into contact with the upper surface of the arm 5, and the arm 5 is pushed downward by the boss 5f. And the boss 5f
Is rotated to the lowest position, the arm 5 becomes substantially horizontal, and the hopper 3b takes an inclined position shown by a dashed line in FIG.

The retard roller 8 is supported by a base 12 rotatably connected to a second support shaft 4b disposed in the housing 1 and parallel to the first support shaft 4a. It comprises a main shaft 8a supported by a bearing 12b provided on the main shaft 12a and a torque limiter 8b interposed and connected between the main shaft 8a. A transmission shaft 8c for connecting to a motor (not shown) for driving the retard roller 8 to rotate is connected to the main shaft 8a by a flexible joint 8d. This flexible joint 8d
Is, for example, a tube made of synthetic resin, and its position is fixed to the transmission shaft 8c with respect to the main shaft 8a.
Even if the position changes vertically, the rotation is transmitted in accordance with the position change.

At one end of the base 12, a tension coil spring 12c is interposed between the base 12 and the bottom of the housing 1.
The base 12 is urged clockwise around the second support shaft 4b in FIG. 2 by the coil spring 12c. Therefore, the retard roller 8 is held in a state pressed against the separation roller 7 with a constant pressing force corresponding to the tensile force of the coil spring 12c.

The function of the torque limiter 8b connected between the retard roller 8 and the main shaft 8a is as described in the conventional example, and the main shaft 8a always rotates counterclockwise in FIG. When the paper is below the critical set torque of the torque limiter 8b, that is, when there is a double feed of the paper, the retard roller 8 rotates integrally with the main shaft 8a and pushes the paper back to the hopper 3b side. When the load is applied, the motor rotates counterclockwise in FIG.

A torsion spring 13 of two torsion coil springs extrapolated around the second support shaft 4b is connected to the base 12 holding the retard roller 8, and the base 12 is rotated clockwise in FIG. Energize. The torsion spring 13 has two hooks 13a and 13b like the torsion spring 9 provided around the first support shaft 4a, and the hook 13a at one end is opened on the rim 12a of the base 12 as shown in FIG. The hook 13 on the other end is inserted into the hole 12a-1.
b is a free end. A separating cam 14 for adjusting the force of the torsion spring 13 is disposed in contact with the hook 13b at the free end.

The separating cam 14 is arranged in parallel with the adjusting shaft 11 and is fixed to a rotating support shaft 15 rotatable around its axis, and its outer shell is substantially eccentric with respect to the rotating support shaft 15. The hook 13b is circular and is pressed in a direction to tighten the hook 13b in the winding direction of the torsion spring 13. As shown in FIG. 4, spur gears 16a and 16b are attached to the adjustment shaft 11 and the rotation support shaft 15, and intermediate teeth 16c are interposed therebetween.
When a is rotated, the rotation support shaft 15 can be rotated in the same direction simultaneously with the rotation of the adjustment shaft 11. Therefore,
By operating the adjustment dial 11a, the posture of the separation cam 14 abutting on the hook 13b is changed, and the degree of tightening of the torsion spring 13 in the winding direction is adjusted.

FIG. 5 shows a hopper cam 10 and a separating cam 1.
FIG. 9 is a schematic diagram for explaining adjustment of the urging force of the torsion springs 9 and 13 according to the posture of FIG.

FIG. 4A shows a state in which the pressing force of the hopper 3b against the pickup roller 6 and the pressing force of the retard roller 8 against the separation roller 7 are set to the maximum, respectively. Reference numeral 14 denotes an outer peripheral surface farthest from the center of rotation of the adjustment shaft 11 and the rotation support shaft 15, and hooks 9 b of the torsion springs 9, 13.
13b. At this time, the degree of tightening of the torsion springs 9 and 13 in the winding direction around the adjustment shaft 11 and the rotation support shaft 15 is maximized, and the arm 5 and the base 12 are clocked around the first and second support shafts 4a and 4b, respectively. It will be strongly biased in the direction.

FIG. 4B shows the state in which the maximum setting of FIG.
Is turned counterclockwise in the figure to set the pressing force of the hopper 3b and the retard roller 8 to the minimum. In this state, the peripheral surfaces of the hopper cams 10 and the separation cams 14 whose eccentric amounts are short abut against the hooks 9b and 13b, and the degree of tightening of the torsion springs 9 and 13 in the winding direction is reduced, and the hopper 3b Both the pressing force of the pickup roller 6 and the pressing force of the retard roller 8 on the separation roller 7 are reduced.

When the adjustment dial 11a is rotated in this manner, the rotation support shaft 15 rotates in the same direction in conjunction with the adjustment shaft 11, so that the torsion springs 9 and 13 push the hopper 3b and the retard roller 8 to be set on the hopper 3b and the retard roller 8, respectively. The pressure can be changed at the same time. In this adjustment of the pressing force, either the pressing force on the hopper 3b side or the pressing force on the retard roller 8 side is either loosened or increased.
The biasing force of the torsion springs 9, 13 is adjusted steplessly.

In the above configuration, when the pickup roller 6 and the separation roller 7 are driven to rotate, the uppermost sheet mounted on the hopper 3b is fed out by friction with the pickup roller 6, as in the conventional example. And
The separation roller 7 and the retard roller 8 form a pair, and as described above, the function of the torque limiter 8b causes the paper to be conveyed or pushed back for the multi-feed.

Here, when the paper is fed from the hopper 3b, if the pressing force of the paper against the pickup roller 6 is too strong, not only the paper is easily fed out in the multi-feed state, but also the function of preventing the double-feed by the retard roller 8. Has also been described earlier. Further, since the friction coefficient is different depending on the quality of the paper, the nip force between the separation roller 7 and the retard roller 8, that is, the pressing force between the two, is set so that the critical setting torque of the torque limiter 8b works properly. Must.

On the other hand, in the present invention, as described with reference to FIG. 5, when the adjustment dial 11a is rotated, the postures of the hopper cam 10 and the separation cam 14 are simultaneously changed, and the hopper 3b and the pickup roller 6 are moved. And separation roller 7
The pressing force between the roller and the retard roller 8 can be adjusted. In this adjustment, in order to optimize the function of separating the sheet by the separation roller 7 and the retard roller 8 from the sheet feeding by the pickup roller 6, the following condition may be satisfied.

Here, the separation roller 7 and the retard roller 8
For properly operating the sheet P separation function by
The conditions are as follows, and will be described with reference to FIG. Less than
In the conditional expression, Pr: the pressing force of the retard roller 8,
T: critical set torque of torque limiter 8b, r: retarder
Radius of roller 8, μ₀: Separation roller 7 and retard draw
Coefficient of friction between the sheet P and m: m: mass of one sheet of paper P.
At this time, T, r, μ ₀, M are constants.

(1) When there is no sheet P between the separation roller 7 and the retard roller 8: the retard roller 8 contacts and rotates with the separation roller 7, that is, the direction indicated by the solid line in FIG. Rotates counterclockwise. The condition for this is that when the transport force due to the contact between the separation roller 7 and the retard roller 8 is F, F = μ ₀ · Pr> T /
r. Therefore, the following equation (1) is obtained.

Pr> (1 / μ ₀ ) × (T / r) (1) (2) The paper P is placed between the separation roller 7 and the retard roller 8.
When there is only one sheet: there is no slip between the separation roller 7 and the sheet P and the sheet P is fed, and at the same time, there is no slip between the retard roller 8 and the sheet P and the sheet P is fed. Then, the retard roller 8 rotates together with the separation roller 7. Conditions for this is, when the coefficient of friction between the retard roller 8 and the sheet P and mu _2, a _{μ 2 · Pr> T / r} . Therefore, the following equation (2) is obtained.

Pr> (1 / μ ₂ ) × (T / r) (2) Then, as a condition of the conveying force for conveying the sheet P, F ₁ : Conveyance force, Fp:
F ₂ : Return force of retard roller 8, F ₃ : Friction force between papers P due to pressing force of hopper 3 b, F ₄ : Papers P due to own weight of first paper P 6B, the following equation is obtained.

F ₁ + Fp> F ₂ + F ₃ + F ₄ where μ ₁ : Coefficient of friction between separation roller 7 and paper P μ ₄ : Coefficient of friction between pickup roller 6 and paper P μp: between paper P When the friction coefficient m is the weight of one sheet P, Pp is the pressing force of the hopper 3b, the above inequality is rewritten as the following equation (3).

Pr> (1 / μ ₁ ) × (T / r) + (1 / μ ₁ ) × {(μp−μ ₄ ) × Pp + μp × m} (3) (3) Separation roller 7 and retard Paper P between roller 8
When there are two sheets: the sheet P in contact with the sheet P is returned to the hopper 3b by the retard roller 8 against the frictional force acting between the sheets P. Conditions for this is, F _5: frictional force between the sheet P by the pressing force of the separation roller 7, F _6: frictional force between the sheet P by the pressing force of the hopper 3b, F _7: self weight of the first sheet P frictional force between the sheet P by, F _8: return force of the retard roller 8, F _9: frictional force between the sheet P by the pressing force of the hopper 3b, F _10: paper due to the weight of 1 to 2 sheet of paper P P Assuming that the frictional force is between, the following equation is obtained from FIG.

F ₈ > F ₅ + F ₆ + F ₇ + F ₈ + F ₉ + F ₁₀ By rewriting this equation using Pr, μp, Pp, and m introduced in equation (3), the following equation (4) is obtained. can get.

Pr <(1 / μp) × (T / r) − (2 × Pp + 3 × m) (4) From the above conditional expressions, the separation roller 7 of the retard roller 8
The pressing force Pr is determined using the larger of Expression (1) and Expression (2) as the lower limit. Equation (3)
And Equation (4) are inequalities using Pr and Pp as variables. Therefore, by substituting numerical values such as the critical setting torque of the torque limiter 8b and the friction coefficient of the paper P to be used into these Equations (3) and (4). , Pr and Pp are determined. If a value equal to or larger than the lower limit value of Pr specified by Expression (1) or Expression (2) is specified, Pp
Takes the maximum value in the range of the magnitude relationship with Pr as the optimum value.

As described above, the conditions for optimizing the sheet separation by the separation roller 7 and the retard roller 8 from the sheet feeding by the pickup roller 6 can be optimized by the pressing force Pr of the retard roller 8 and the pressing force Pp of the hopper 3b. Can be expressed. Since these pressing forces Pr and Pp are determined by the urging forces of the torsion springs 13 and 9, respectively, by rotating the separation cam 14 and the hopper cam 10 for adjusting the urging force, the sheet feeding and the paper are performed. Optimization of the separation function can be performed.

Here, the hopper cam 10 and the separation cam 1
4 is simultaneously rotated by the adjustment dial 11a to change its posture, but it is sufficient if each member fulfills its function so as to satisfy the above conditions for Pr and Pp. That is, the hopper cam 10 and the separation cam 14
The biasing force of the torsion springs 9 and 13 is determined by the shape of the peripheral surfaces of the cams 10 and 14 for hoppers and separation, the rotation direction and rotation angle thereof, the spring constant of the torsion springs 9 and 13, and the gears 16a to 16c. It can be adjusted in various ways depending on the factors such as the gear ratio. Therefore, if the maximum and minimum loading weights of paper and the friction coefficient for each paper quality are set in advance as design conditions, a paper feeder that satisfies the conditions of Pr and Pp optimal for paper feeding and paper separation can be obtained.

For example, when the size of the sheet is large, the load on the hopper 3b increases, and the force for pushing the hopper 3b around the pin 3d is strong. Therefore, in order to urge the hopper 3b upward against this pressing force to compensate the pressing force to the pickup roller 6, the hopper cam 10 is set to the posture shown in FIG. Set larger. As a result, even if the load on the sheet is large, the urging force of the torsion spring 9 is transmitted to the hopper 3b via the arm 5, and the sheet on the hopper 3b is abutted against the pickup roller 6 with an appropriate pressing force. Can be. Conversely, when the paper size is small and the load on the paper is light, if the hopper cam 10 is rotated as shown in FIG. 5B, the urging force of the torsion spring 9 is reduced. Therefore, when replacing large-sized paper with small paper, the biasing force is excessive when the hopper cam 10 is in the position shown in FIG. can get.

Further, simultaneously with the adjustment of the pressing force of the hopper 3b, the pressing force of the retard roller 8 against the separation roller 7 is optimized at the same time. Since the adjustment of the pressing force is mainly intended to prevent double feed due to the difference in the coefficient of friction based on the paper quality of the paper, the separation cam 14 is adjusted to correspond to the relationship between the size of the paper to be used and the paper quality. If such a function can be performed, double feeding of sheets can be reliably prevented.

As described above, according to the present invention, even if there is a difference in weight due to the size of the paper or a difference in the coefficient of friction due to the quality of the paper, the hopper cam 1 can cope with each type of paper.
By adjusting the rotation posture of the cam 0 and the separating cam 14 with respect to the torsion springs 9 and 13, respectively, it becomes possible to achieve good sheet feeding and prevent double feeding.

[0057]

According to the present invention, the pressing force between the hopper and the pick-up roller is adjusted so that the paper can be reliably fed even when the size and quality of the paper are variously changed. Can be adjusted so as to regulate the double feeding of the paper, so that the single-sheet feeding and the prevention of the double feeding can be performed irrespective of the type of the paper. If the pressing force between the hopper and the pickup roller and between the separation roller and the retard roller can be set at the same time, the adjustment work for each sheet can be simplified and the apparatus can be optimally used as a general-purpose machine.

[Brief description of the drawings]

FIG. 1 is an external perspective view of an image scanner including a sheet feeding device of the present invention.

FIG. 2 is a longitudinal sectional view showing a main part of the sheet feeding device.

FIG. 3 is a plan view showing a main part of FIG. 2 without a separation roller;

FIG. 4 is a schematic view showing the connection between the adjustment shaft and the rotating shaft by a gear train.

5A and 5B are diagrams illustrating setting of the biasing force of the torsion spring by the hopper cam and the separating cam, wherein FIG. 5A illustrates the biasing force when the biasing force is maximized, and FIG. Diagram showing when is minimized

FIG. 6 is an explanatory diagram for finding optimum conditions for a pressing force of a hopper on a pickup roller and a pressing force of a separation roller of a retard roller.

FIG. 7 is a schematic view showing a main part of a conventional example.

[Description of Signs] 1 Housing 1a Operation section 2 Sub-housing 2a Collection tray 3 Paper feed unit 3a Frame 3b Hopper 3c Side guide 3d Pin 4a First support shaft 4b Second support shaft 5 Arm 5a Holding shaft 5b Support roller 5c Engagement hole 5d Operation shaft 5e Flange 5f Boss 6 Pickup roller 7 Separation roller 7a Drive shaft 8 Retard roller 8a Main shaft 8b Torque limiter 8c Transmission shaft 8d Flexible joint 9 Torsion spring 9a, 9b Hook 10 Hopper cam 11 Adjustment shaft 11a Adjustment Dial 12 Base 12a Rim 12a-1 Engagement hole 12b Bearing 12c Coil spring 13 Torsion spring 13a, 13b Hook 14 Separation cam 15 Rotating support shaft 16a, 16b Gear 16c Middle teeth

[Procedure amendment]

[Submission date] December 20, 1999 (1999.12.
20)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Correction contents]

[Claims]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

[0015]

The paper feeder according to the present invention comprises:
A first transporting means, one end of which faces the first transporting means;
A hopper rotatably supported and capable of loading a print medium;
The pressing force of the hopper against the first transfer means can be adjusted.
Functioning first adjusting means and a second transporting means capable of transporting the printing medium.
Feeding means, and a rotational torque opposed to the second conveying means.
A third conveying means having a torque control means for controlling,
The pressing force of the third conveying means on the second conveying means
Adjustable second adjusting means, the first adjusting means and
Control means for controlling the second adjustment means .

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Deleted

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

[0017]

DETAILED DESCRIPTION OF THE INVENTION The first aspect of the present invention is a first aspect of the present invention.
Transport means (pickup roller) and the first transport hand
Print media can be loaded with one end rotatably supported facing the step
Hopper and the first transfer means of the hopper.
First adjusting means capable of adjusting the pressing force
A second conveying means (separation roller) capable of feeding,
Torque control means for controlling rotation torque facing the transport means
A third transporting means (retard roller) having
Adjusting the pressing force of the third conveying means on the second conveying means.
Adjustable second adjusting means, said first adjusting means and
Control means for controlling the second adjusting means.
This is a paper feeding device with a characteristic that the pressing force between the hopper and the pickup roller and the pressing force between the separation roller and the retard roller are appropriate even if the size and quality of the paper loaded on the hopper are various. , An effect of preventing double feeding of sheets is achieved.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

Even if the size and quality of the paper loaded on the hopper are various, various types of paper can be supplied by the control means so that the cut sheet can be fed from the hopper and the double feed by the separation roller and the retard roller can be prevented. The effect is that it can be adjusted according to.

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] 0019

[Correction method] Change

[Correction contents]

Further, even if the size and quality of the paper loaded on the hopper are various, the pressing force between the hopper and the pickup roller and the pressing force between the separation roller and the retard roller are properly adjusted. Thus, an effect of preventing double feeding of sheets is achieved.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2H072 BA08 BA17 BA20 3F343 FA03 FB03 FC01 GA02 GB01 GC01 GD01 HA12 HB01 HD08 HD09 HD17 JA19 JD03 JD09 JD33 LA04 LA15 LC07 LD04 LD25

Claims (3)

[Claims] A pickup roller disposed at a starting end of a line of a sheet to be fed; and a top surface of a sheet disposed below the pickup roller and stacked and mounted on an upper surface of the pickup roller. A hopper movable in the abutting direction, a separation roller and a retard roller for preventing double feed, which are respectively disposed downstream of the pickup roller and above and below a path line of the sheet, wherein the hopper and the pickup roller And the pressing force between the separation roller and the retard roller can be set so as to satisfy the condition of the cut sheet feeding of the sheet and the condition of the double feed control of two or more sheets. Paper feeder. 2. A pickup roller disposed at a start end of a line of a sheet to be fed, and a top surface of a sheet disposed below the pickup roller and stacked and mounted on an upper surface thereof is formed on a peripheral surface of the pickup roller. A hopper that can be operated to move in the abutting direction, and a separation roller and a retard roller for preventing double feeding that are respectively disposed downstream of the pickup roller and above and below a path line of the sheet, and the hopper and the pickup roller And a pressing force adjusting means for adjusting the pressing force between the separation roller and the retard roller. 3. The pressing force adjusting means controls the pressing force between the hopper and the pick-up roller and the pressing force between the separation roller and the retard roller according to conditions for the cut-sheet feeding of the sheet. 3. The paper feeding device according to claim 2, wherein a relationship that satisfies the condition of the double feed control of two or more sheets can be simultaneously set.