JPH11124244A - Paper feeding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce streaks put on the printing surface of a paper sheet. SOLUTION: An edge part along the paper sheet feeding direction (a) of a separating pad 40 is inclined relative to a paper sheet feeding direction. The opposed surface 40a of the separating pad to a paper feeding roller has an inclined surface 40a2 which is apart more from the paper feeding roller, as viewed in the axial direction of the paper feeding roller, than the tangential line (t) with the circular surface of the paper feeding roller at a pressure contact part T between the separating pad 40 and the paper feeding roller moving to the upstream side of a paper feeding direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paper feeder for feeding paper (plain paper, coated paper, OHP (overhead projector) sheets, glossy paper, glossy film, cut sheets such as postcards, envelopes, etc.). . More specifically, the present invention relates to a so-called pad separation type sheet feeding device that separates and feeds a sheet by a sheet feeding roller and a separation pad, and a sliding contact surface of the fed sheet with the separation pad is a printer or the like. The present invention relates to a sheet feeding device which is particularly effective when a printing surface is used.

[0002]

2. Description of the Related Art FIG. 5A is a conceptual view (side view) showing an example of a conventional paper feeder SF and a printer PR using the paper feeder SF, and FIG. 5B is a plan view of a separation pad. FIG.

A paper feeder SF feeds a plurality of sheets P stacked on a hopper 1 to a rotating paper feed roller 2 by a hopper spring 1.
a, the paper being fed is pressed and fed between the paper feed roller 2 and the separation pad 3 pressed against the paper feed roller 2 by an urging force F by a compression spring or the like (not shown), thereby feeding the paper. Is separated from the next sheet P2 (including the next sheet P3, etc., the same applies hereinafter), and only the top sheet P1 is fed in the direction of arrow a.

[0004] The separation operation will be described in detail as follows.

When the paper feed roller 2 rotates in the direction of the arrow and its circumferential surface 2a comes into contact with the uppermost paper P1 of the paper P, when the paper P1 is fed toward the separation pad 3, When the next sheet P2 is attracted to the sheet P1 by the action of static electricity or when a frictional force acts between the sheet P1 and the sheet P2, the sheet P2
2 may be sent together with the sheet P1.

However, the movement of the sheet P2 is hindered by the tip of the sheet P2 abutting against the separation pad 3, and the sheet P2 can be temporarily separated from the sheet P1.

Further, when the friction coefficient between the paper feed roller 2 and the paper P is μ1, the friction coefficient between the separation pad 3 and the paper P is μ2, and the friction coefficient between the papers is μ3, μ1
>Μ2> μ3, the feed roller 2 and the separation pad 3 are configured so that the feed roller 2
When the sheet P1 and the sheet P2 are both pressed by the paper feed roller 2 and the separation pad 3 as the paper P rotates, the movement of the sheet P2 is hindered by the frictional force between the sheet P2 and the separation pad 3, and the secondary Paper P1 is separated from the paper P1
Only will be fed.

As described above, only the uppermost sheet P1 is fed.

The fed sheet P1 is reversed and conveyed by being wound around a sheet feed roller 4 and is supplied below a print head 5. After being printed by the print head 5, the sheet P1 is discharged. Is discharged to the department.

Reference numerals 5 and 6 denote pinch rollers, and reference numerals 7 and 8 denote paper guides.

[0011]

In the above-described paper feeding device and printer, the paper P1 is reversed and fed to the print head 5, so that the sliding contact surface Ps with the separation pad 3 is in contact with the printing surface. Become.

On the other hand, as shown in FIG. 5B, the separation pad 3 in the conventional sheet feeding device has a pad surface (sheet feeding roller 2).
3a) was rectangular, and edges 3e, 3e (edges of the pad surface 3a) along the paper feeding direction a were parallel to the paper feeding direction a.

For this reason, the paper P1 is nipped by the paper feed roller 2 and the separation pad 3, and its printing surface Ps is
When the paper is fed while being slid in contact with the edge portions 3e, there is a problem that stripe-like scratches are easily caused by the slidable contact with the edges 3e. In particular, when the paper P is a glossy paper, a glossy film, or the like having a glossy surface applied to its printing surface, the stripe-shaped scratches are easily conspicuous.

An object of the present invention is to solve the above-mentioned problems and to provide a sheet feeding device capable of reducing the above-mentioned stripe-like scratches.

[0015]

According to a first aspect of the present invention, there is provided a sheet feeding apparatus for separating a sheet by a sheet feeding roller and a separation pad pressed against the sheet feeding roller via a sheet. The separation pad is characterized in that an edge of the separation pad along the sheet feeding direction is inclined with respect to the sheet feeding direction.

According to a second aspect of the present invention, in the sheet feeding apparatus according to the first aspect, the surface of the separation pad facing the sheet supply roller is separated from the separation pad when viewed from the axial direction of the sheet supply roller. It is characterized in that it has an inclined surface that moves away from the paper feed roller toward the upstream side in the paper feed direction with respect to the tangent line with the circumferential surface of the paper feed roller at the pressure contact portion with the roller.

[0017]

According to the sheet feeding apparatus of the first aspect, the sheet is separated and fed by the sheet feeding roller and the separation pad pressed against the sheet feeding roller via the sheet.

Since the edge of the separation pad along the sheet feeding direction is inclined with respect to the sheet feeding direction, the sliding contact with the edge reduces scratches on the sheet. . Furthermore, since the edge is inclined with respect to the sheet feeding direction, the scratch itself is not easily formed, and
Even if a flaw is present, the flaw is diffused in a direction orthogonal to the sheet feeding direction, and as a result, the flaw is less noticeable.

That is, according to the sheet feeding device of the first aspect, the above-mentioned striped scratches are reduced.

According to a second aspect of the present invention, in the sheet feeding apparatus according to the first aspect, the surface of the separation pad facing the sheet feeding roller is separated from the separation pad when viewed from the axial direction of the sheet feeding roller. Since it has an inclined surface that moves away from the paper feed roller toward the upstream side in the paper feed direction than the tangent to the circumferential surface of the paper feed roller at the pressure contact portion with the paper feed roller, the paper feed roller and the separation pad Can be reduced, and as a result, the above scratches can be further reduced.

This will be described in detail.

In the pad separation type sheet feeding device, the movement of the next sheet P2 which is likely to be sent together with the sheet P1 is temporarily hindered by the leading end of the sheet P2 hitting the separation pad 3, and the sheet P1 As shown in FIG. 6, in order to obtain the primary separation effect satisfactorily, the separation pad 3 can be separated from the pad surface (the surface facing the paper feed roller) 3a. It is desirable to set the collision angle θ1 of the paper P relatively large.

However, since the conventional pad surface 3a is formed of only one plane, if the collision angle θ1 is to be increased, in FIG. 6, the separation pad 3 is connected to the feed roller 2 in order to increase the collision angle θ1. As can be seen by rotating clockwise around the pressure contact portion T with
, The wrapping angle θ2 of the sheets P1 and P2 becomes large. When the wrapping angle θ2 increases, not only the conveying force of the paper feed roller 2 on the sheet P1 but also the conveying force on the sheet P2 increases due to the action of the frictional force between the sheets. It is difficult to reliably separate the sheet P2, and the sheet P2 is easily sent together with the sheet P1 (overlapping is likely to occur).

In order to prevent this, in order to reliably obtain the secondary separation action, the pressure contact force F between the sheet feeding roller 2 and the separation pad 3 must be increased. The paper P is more easily scratched.

On the other hand, according to the paper feeder of the second aspect, the surface of the separation pad facing the paper feed roller is pressed against the separation pad and the paper feed roller when viewed from the axial direction of the paper feed roller. Than the tangent to the circumference of the paper feed roller in the
Since the sheet has an inclined surface that moves away from the sheet supply roller toward the upstream side in the sheet supply direction, a collision angle of the sheet with respect to the pad surface is increased by the inclined surface.

Therefore, according to the paper feeding device of the second aspect, the collision angle of the paper with the separation pad can be increased without increasing the winding angle of the paper with the paper feeding roller. With a relatively small pressing force between the paper feed roller and the separation pad, the paper can be reliably separated and fed one by one.

That is, according to the paper feeder of the second aspect, the pressure contact force between the paper feed roller and the separation pad can be reduced, and in combination with the configuration of the first aspect, the flaws can be reduced. Can be further reduced.

[0028]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partially omitted side sectional view showing a main part of an embodiment of a sheet feeding apparatus according to the present invention, and FIG. 2 is a partially enlarged view of FIG.

The paper feeder of this embodiment is applied to a printer, and includes a paper feed roller 20 provided in the printer main body 10 and a plurality of paper feed rollers 20 detachably mounted on the printer main body 10. And a separation pad 40 provided on the sheet cassette 30 that stores the sheets P.

As shown in FIG. 1, the paper feed roller 20 is formed in a D shape in a side view having an arc portion (circumferential surface) 20a in contact with the paper P and a straight portion 20b not in contact with the paper. At least the outer peripheral surface of the arc portion 20a is made of a high friction material such as rubber. The paper feed roller 20 is connected to the lever 2
One end is rotatably supported by a shaft 22 and is driven to rotate about the shaft 22 by an appropriate driving means (not shown).

The lever 21 is supported on the frame 11 of the printer body by a shaft 23, and is rotatable around the shaft 23. A compression spring 24 is provided between the lever 21 and the frame 11 as urging means.
The lever 21 is constantly urged clockwise in the drawing, but its rotation is regulated by the rear end 25 of the lever 21 abutting on the frame 11 as shown by the imaginary line.

The paper feed cassette 30 includes a case main body 31 and
The case body 31 includes a hopper 32 rotatably mounted on the case body 31, and a separation pad 40 incorporated at an upper end of the case body 31. 33 is detachably attached to the printer main body by engaging the engaging portion 33 with the engaging portion 13 of the printer main body 10.

The rear end (left side in FIG. 1 and not shown) of the hopper 32 is rotatably attached to the case body 31. A plurality of sheets P are stacked on the hopper 32 in a stacked state. Is placed. The hopper 32 is moved up by a lift mechanism (not shown) provided in the printer main body 10 during a paper feeding operation, and presses the paper P against the paper feeding roller 20. The pressing force at this time is obtained by the compression spring 24.

The separation pad 40 is made of a material having a coefficient of friction with the sheet P smaller than the coefficient of friction of the sheet feed roller 20 with the sheet P. Each of the friction coefficients is made of a material having a friction coefficient larger than the friction coefficient between sheets. That is, if the friction coefficient between the paper feed roller 20 and the paper is μ1, the friction coefficient between the separation pad 40 and the paper is μ2, and the friction coefficient between the papers is μ3,
μ1>μ2> μ3.

The separation pad 40 includes a separation pad holder 41
Attached to.

FIGS. 3A and 3B are diagrams showing details of the separation pad 40 and the separation pad holder 41. FIG. 3A is a plan view, FIG. 3B is a cross-sectional view (side cross-sectional view) of FIG. () Is a cc cross-sectional view (side cross-sectional view) in which the separation pad 40 in FIG.

The separation pad holder 41 is an integrally molded product, and has a support surface 42 to which the separation pad 40 is fixed, columns 43 provided on both sides below the support surface 42, and a substantially lower center of the support surface 42. And a pair of stop claws 45, which are formed below the support surface 42,
45.

The support surface 42 is formed as a trapezoidal recess as seen in plan view as shown in FIG. 3A, and the bottom surface thereof is formed as shown in FIGS. Face 4
2a and 42b. These two surfaces 42a, 4
2b has a shape of “H” in side view as a whole.

As shown in FIG. 4, the separation pad 40 is formed in a trapezoidal shape in a plan view, which is adapted to the support surface 42. Therefore, the edges 40e, 40e of the separation pad 40 along the sheet feeding direction a in this embodiment are inclined with respect to the sheet feeding direction a.

The separation pad 40 is formed of a foamed urethane rubber sheet or the like, and is attached to the support surface 42 with a double-sided adhesive tape 40b provided on the bottom surface. Therefore, the pad surface (the surface facing the paper feed roller 20) 40a of the separation pad 40 attached has a shape along the support surface 42, that is, two surfaces 40a1 and 40a2. 40a2, when viewed as a whole, assumes the shape of the letter "he" in side view.

Each of the columns 43 has a guide groove 43a formed on the outside thereof.
1, are slidably fitted on guide rails 35, 35 (only one of which is shown) formed on the inner wall surface of a concave pad mounting portion 34 provided at the upper end of the sheet feeding cassette 30 as shown in FIG. . Therefore, the separation pad holder 41 (that is, the separation pad 40) is slidable in the guide groove 43a in the pad mounting portion 34 (so as to be able to protrude and retract with respect to the pad mounting portion 34 of the sheet cassette 30).

Around the cylindrical portion 44, a pad spring 46 (see FIG. 3C) as a biasing means composed of a compression coil spring is mounted. As shown in FIG. 1, the pad spring 46 is provided in a compressed state between the bottom 36 of the pad incorporating portion 34 and the separation pad holder 41, and feeds the separation pad holder 41 (that is, the separation pad 40). The separation pad holder 41 is always urged toward the roller 20 (toward the projecting direction). When the separation pad holder 41 projects, the stop claws 45, 45 engage with the stopper 37 provided in the pad mounting portion 34. Is regulated by

Separation pad 4 incorporated as above
0 is one surface 40a2 of the pad surface (surface facing the paper feed roller 20) 40a as shown mainly in FIG.
However, when viewed from the axial direction of the paper feed roller 20 (in FIGS. 1 and 2), the tangent t between the separation pad 40 and the circumferential surface 20a of the paper feed roller 20 at the pressure contact portion T between the paper feed roller 20 is smaller than that. An inclined surface that moves away from the paper feed roller 20 is formed toward the upstream side (the left side in FIGS. 1 and 2) in the paper feed direction.

The above-described paper feeding device operates as follows.

In the standby state, the lever 21 of the paper feed roller 20 has a rear end 25 in contact with the frame 11 as shown by a virtual line, and the paper feed roller 20 is , And stops with the linear portion 20b facing the paper P. The hopper 32 is at the lower position (the position shown in FIG. 1), and the paper P is not pressed against the paper feed roller 20.

In the paper feeding operation, first, the paper feeding roller 20 temporarily stops after the arc portion 20a rotates (about 90 degrees) so as to correspond to the paper P from the state shown by the imaginary line in FIG. (This state is not shown, but the state shown by the solid line in FIG. 1 shows a state rotated by about 120 degrees, so that it can be easily understood from this.)

Next, the hopper 32 is moved up from the state shown in FIG. 1 by a predetermined amount with respect to the arc portion 20a of the paper feed roller 20 in the stopped state, and the paper P is moved by the arc portion 2 of the paper feed roller 20.
0a. At this time, when the paper P comes into contact with the arc portion 20 a of the paper feed roller 20 with the upward movement of the hopper 32, the paper feed roller 20 is pushed up, and the lever 21 is turned counterclockwise against the urging force of the spring 24. To the rear end 2
5 is separated from the frame 11 as shown by a solid line in FIG. As a result, the paper feed roller 20 is pressed against the uppermost sheet P1 by the urging force of the spring 24.

Thereafter, as shown in FIG.
0 rotates again, and the uppermost sheet P1 is fed toward the separation pad 40. That is, FIG. 1 shows the state at this time.

At this time, as described above, the separation pad 40
When viewed from the axial direction of the paper feed roller 20, the surface 40a facing the paper feed roller is larger than the tangent t of the press contact portion T between the separation pad 40 and the paper feed roller 20 to the circumferential surface 20a of the paper feed roller 20. Has an inclined surface 40a2 that moves away from the paper feed roller 20 toward the upstream side in the paper feed direction.
The sheet P1 (and P2) is formed by the inclined surface 40a2.
Is formed with a large collision angle θ11 (or θ12).

Therefore, the primary separating operation between the uppermost sheet P1 and the next sheet P2 can be favorably obtained.

In FIG. 1, P1 is the hopper 32
The state of the uppermost sheet when the maximum number of sheets of paper P that can be placed on the hopper 32 is stacked is shown, and P1 ′ indicates that the number of sheets of paper placed on the hopper 32 is the minimum number, that is, the last sheet. 3 shows the state of the sheet when it becomes one sheet. In either case, the collision angles θ11 and θ12 are also relatively large due to the inclined surface 40a2. For example, FIG.
Is about 33 °, and θ12 is about 28 °.

Thereafter, as the paper feed roller 20 further rotates, the paper P1 is further fed. At this time, even if the paper P2 is to be fed together with the paper P1, the paper P1 is sandwiched between the paper feed roller 20 and the separation pad 40. Paper P2 at pressure section T
Is disturbed, and is separated from the sheet P1 secondarily,
Only the sheet P1 is fed in the direction of arrow a in FIG. In FIG. 1, reference numeral 14 denotes a guide for guiding the fed paper, and the fed paper P1 is
After that, the paper is wound around a paper feed roller (not shown) and conveyed reversely, supplied below a print head (not shown), and printed by the print head.

When the sheet P1 is fed, the sheet P1 is fed while its printing surface (the lower surface in this embodiment) Ps is slid on the separation pad 40, as described above. Of the separation pad 40 along the paper feeding direction a
0e and 40e are inclined with respect to the sheet feeding direction a.
Is reduced. Furthermore, since the edges 40e, 40e are inclined with respect to the sheet feeding direction a, the scratches themselves are less likely to be formed, and even if the scratches are formed, the scratches are removed from the sheet feeding direction a. Is diffused in a direction perpendicular to the direction, and as a result, the scratch becomes less noticeable.

Then, after the paper feed roller 20 makes one rotation from the state shown by the imaginary line in FIG. 1 and returns to the state shown by the imaginary line, the hopper 32 moves down to the same state as the standby state described above. Become.

According to the above-described paper feeder, the following operation and effect can be obtained.

(A) Since the edges 40e of the separation pad 40 along the sheet feeding direction a are inclined with respect to the sheet feeding direction a, the sheet is brought into sliding contact with the edges 40e. The scratches on P will be reduced. Furthermore, since the edges 40e, 40e are inclined with respect to the sheet feeding direction a, the scratches themselves are less likely to be formed, and even if the scratches are formed, the scratches are removed from the sheet feeding direction a. Is diffused in a direction perpendicular to the direction, and as a result, the scratch becomes less noticeable.

(B) The surface 40a of the separation pad 40 facing the paper feed roller 20 has the circle of the paper feed roller 20 at the pressure contact portion T between the separation pad 40 and the paper feed roller 20 when viewed from the axial direction of the paper feed roller. It has an inclined surface 40a2 that moves away from the paper feed roller 20 toward the upstream side in the paper feeding direction from a tangent t to the peripheral surface 20a.
As a result, the collision angle θ11 or θ12 of the sheet P is increased.

Therefore, according to this paper feeder, the collision angle of the paper with the separation pad 40 can be increased without increasing the wrap angle of the paper with respect to the paper feed roller 20, and as a result, a relatively small angle is obtained. Then, the paper can be surely separated and fed one by one by the pressing force of the paper feed roller 20 and the separation pad 40.

That is, according to this sheet feeding device, the pressure contact force between the sheet feeding roller 20 and the separation pad 40 can be reduced, and the above-mentioned scratches can be further reduced in combination with the above-mentioned effect (a). Can be done.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the present invention.

For example, in the above-described embodiment, the shape of the separation pad 40 is trapezoidal in plan view. However, the present invention is not limited to this, and the edge along the sheet feeding direction a is inclined with respect to the sheet feeding direction a. Any shape is acceptable. Therefore, for example, the edge (40e) may be a curved line instead of a straight line.

In the above embodiment, the separation pad 4
0 of the sheet feed roller 20 and two flat surfaces 40a.
Although they were formed with a1 and 40a2, they could also be formed with a curved surface. When viewed from the axial direction of the paper feed roller, the separation pad 4
Feed roller 2 at the pressure contact portion T between the feed roller 0 and the feed roller 20
0, the inclined surface 40 that moves away from the paper feed roller 20 toward the upstream side in the paper feed direction from the tangent t to the circumferential surface 20a.
a2 is sufficient.

[0064]

According to the first or second aspect of the present invention, the above-mentioned stripe-like scratches can be reduced.

Further, according to the paper feeding apparatus of the second aspect, the above-mentioned flaw can be further reduced.

[0066]

[Brief description of the drawings]

FIG. 1 is a partially omitted side sectional view showing a main part of an embodiment of a sheet feeding device according to the present invention.

FIG. 2 is a partially enlarged view of FIG.

3A and 3B are diagrams showing details of a separation pad 40 and a separation pad holder 41, wherein FIG. 3A is a plan view, FIG. 3B is a cross-sectional view taken along line bb (side cross-sectional view) in FIG. FIG. 2 is a cc cross-sectional view (side cross-sectional view) in which the separation pad 40 in FIG.

FIG. 4 is a view showing a separation pad, (a) is a plan view,
(B) is a right side view when FIG. (A) is a front view.

FIG. 5A is a conceptual diagram (side view) showing an example of a conventional paper feeding device SF and a printer PR using the paper feeding device SF, and FIG. 5B is a plan view of a separation pad.

FIG. 6 is a conceptual diagram for explaining a conventional technique, and FIG.
FIG.

[Explanation of symbols]

 P paper 20 Paper feed roller 20a Circumferential surface 40 Separation pad 40a Pad surface (opposing surface) 40e Edge 40a2 Inclined surface T Pressure contact portion t Tangent line

Claims (2)

[Claims] 1. A sheet feeding device for separating and feeding a sheet by a sheet feeding roller and a separation pad pressed into contact with the sheet feeding roller via a sheet, wherein the sheet is fed in a sheet feeding direction of the separation pad. A sheet feeding device, wherein an edge along the sheet is inclined with respect to a sheet feeding direction. 2. A surface of the separation pad facing the paper feed roller is, when viewed from the axial direction of the paper feed roller, larger than a tangent line of the pressure contact portion between the separation pad and the paper feed roller with the circumferential surface of the paper feed roller. 2. The sheet feeding device according to claim 1, wherein the sheet feeding device has an inclined surface that moves away from the sheet feeding roller toward the upstream side in the sheet feeding direction.