JPH1072144A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly prevent a skew of a paper sheet by registering the paper sheet tip along the nip part tip by once reversely rotating carrying roller pairs when a separating pad does not interposingly press the paper sheet with a circular arc part of a paper feeding roller in a paper feeder composed of the paper feeding roller having a D-shaped cross section and an operation idle roller. SOLUTION: After the tip P1a of a paper sheet P1 is put in a condition of slightly passing through a nip part N of carrying roller pairs 2 and 3, the carrying roller pairs 2 and 3 are once reversely rotated. For example, when the paper sheet P1 skews as shown by a virtual line, a tip part P1a2 passes after a tip part P1a1 passes. In this situation, since a paper sheet rear part is interposingly pressed by a contact part of a separating pad and an idle roller, when carrying force acts only on the paper sheet tip part P1a2, the paper sheet P1 rotates in the arrow X1 direction. As a result, the tip P1a of the paper sheet is registered along the nip part N of the carrying roller pairs 2 and 3 as shown by a broken line.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to one sheet of laminated paper (plain paper, coated paper, OHP (overhead projector) sheet, glossy paper, cut sheet of glossy film, etc.) from the top one. The present invention relates to a printer that feeds paper one by one and prints the paper. In particular, the present invention relates to a technique for preventing a fed sheet from being conveyed in a state of being inclined with respect to a conveying direction, that is, a technique for preventing skew of the sheet.

[0002]

2. Description of the Related Art An outline of a conventional general printer is shown in FIG.
Shown in

In FIG. 1, reference numeral 1 denotes a sheet feeding device, which feeds sheets P one by one.

The fed sheet P is transported by a pair of transport rollers 2 and 3.
The paper is conveyed while being pinched by the printer, printed by the printing means 4, and then discharged out of the apparatus by discharge roller pairs 5 and 6.

[0005] As the sheet feeding device 1, a device shown in Fig. 14 has been conventionally known (Japanese Utility Model Publication No. 8-3396).

In FIG. 1, reference numeral 10 denotes a substantially D-shaped paper feed roller as viewed from the side, which has an arc portion 10a and a straight portion 10b.

Reference numeral 11 denotes a guide block on which a shaft 10c of the sheet feed roller 10 is supported.

A cassette 12 has a loading plate 12 inside.
a is provided. A plurality of sheets P are set in a stacked state on the stacking plate 12a. Reference numeral 12c denotes a spring, and the paper P is urged toward the paper feed roller 10 by the spring 12c.

Reference numeral 13 denotes a separation pad, and the bracket 13
a. The separation pad 13 is located in the rotation orbit of the arc portion 10a of the paper feed roller 10,
A spring 14 urges the paper feed roller shaft 10c along a guide 15.

Reference numeral 16 denotes an idle roller rotatably mounted on the guide block 11, and 17 denotes a guide block.
This is a movable idle roller in which a shaft 17a is movably attached to one long groove 11a. Movable idle roller 17
Is biased toward the separation pad 13 by the spring 18 and is in contact with the separation pad 13.

The urging force F2 of the spring 18 is set smaller than the urging force F1 of the spring 14 of the separation pad 13 (that is, F1> F2).

The above-described paper feeding device operates as follows.

In a standby state, as shown in FIG. 14, the linear portion 10b of the paper feed roller 10 is in a state of facing the paper P, and the paper feed roller 10 is not in contact with the paper P.
The urging force F2 of the spring 18 of the movable idle roller 17 is equal to the urging force F2 of the spring 14 of the separation pad 13.
Since it is set to be smaller than 1, the movable idle roller 17 is pushed up by the separation pad 13, and the shaft 17a is in contact with the upper end of the long groove 11a.

During the paper feeding operation, the paper feeding roller 10 rotates in the direction of the arrow, and its arc portion 10a comes into contact with the uppermost paper P1 of the paper P, so that the paper P1 faces the separation pad 13. Sent. At this time, the sheet P2 is fed together with the sheet P1 because the next sheet P2 is attracted to the sheet P1 by the action of static electricity or a frictional force acts between the sheet P1 and the sheet P2. May be used.

However, the sheet P2 is separated from the sheet P1 by the separation pad 13 as follows, and only the uppermost sheet P1 is fed.

That is, when the leading end of the sheet P2 hits the separation pad 13, its movement is hindered, and the sheet P2 can be separated from the sheet P1 temporarily.

The frictional force between the arc portion 10a of the paper feed roller 10 and the paper P1 is f1, and the paper P2 and the separation pad 1
Assuming that the frictional force between the sheet P3 and f3 is f2 and the frictional force between the sheet P1 and the sheet P2 is f3, the paper feed roller 10 and the separation pad 13 are configured such that a relationship of f1>f2> f3 is established. Therefore, when the paper P1 and the paper P2 are pressed by the arc portion 10a of the paper feed roller and the separation pad 13 as the paper feed roller 10 rotates, the paper P2
The movement is hindered by the frictional force with the separation pad 13, and the paper P2 is secondarily separated from the paper P1, and only the paper P1 is fed. Note that the separation pad 13 is
Since it is located in the rotation orbit of the circular arc portion 10a of the paper feed roller 10, the circular arc portion 1a rotates to rotate the circular arc portion 1a.
However, since the movable idle roller 17 is urged toward the separation pad 13 by the spring 18, even if the separation pad 13 is pressed down, the movable idle roller 17 comes into contact with the separation pad 13. The separating operation is performed.

The paper feed roller 10 makes one full rotation and returns to the standby state (the state shown in FIG. 14).

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

The paper fed in such a manner may be fed obliquely with respect to the traveling direction.
The fed paper is usually transported by the transport roller pairs 2 and 3 and printed by the printing means 4 as shown in FIG. 13, but the paper is transported in an oblique state. That is, if the sheet is skewed, the printing state will also be skewed, so it is necessary to prevent the sheet from being skewed.

As a technique for preventing the skew of the sheet, conventionally, as shown in FIGS. 15A and 15B, the sheet is fed by a single sheet feed roller 7 and the fed sheet P1 is fed. Tip P1a
There is known a technique in which the sheet feed roller 7 is stopped after passing through a nip portion (pressing portion) N of the pair of conveying rollers 2 and 3, and the pair of conveying rollers 2 and 3 are once rotated reversely.

When the sheet P1 is skewed and the transport rollers 2 and 3 rotate in reverse, the timing at which the leading end P1a of the sheet passes through the nip portion N of the transport rollers 2 and 3 in the reverse direction is determined by the timing. Different in the width direction. When the sheet P1 is skewed, for example, as shown by the imaginary line in FIG. 15A, the leading end P1 on the upper side in FIG.
After the passage of a1, the front end P1a2 on the lower side passes. That is, the tip P on the upper side
Although the conveying force of the conveying roller pairs 2 and 3 does not act on 1a1, a situation occurs in which the conveying force acts on the lower end P1a2.

In such a situation, since the paper feed roller 7 is stopped, the paper P1 rotates in the direction of arrow X in FIG. 15A, and as a result, the leading end P1a of the paper is It will be aligned along the nip portion N.

Thereafter, the paper P1 can be transported straight by rotating the transport roller pairs 2 and 3 forward.

On the other hand, in the paper feeding device of the printer, FIG.
As shown in FIG. 6 (b), there is a printer in which the paper feed tray 12 'is set up and inclined so as to reduce the installation area of the entire printer.

When the sheet feeding tray 12 'is inclined as described above, the weight of the sheet P1 acts on the sheet in the feeding direction at the time of feeding. Therefore, if the sheet feeding roller is single, the sheet is extremely inclined. There is a disadvantage that it is easy to perform.

In such an apparatus, FIG.
As shown in (a), by providing at least one pair of paper feed rollers 7 ', skew during paper feeding is reduced.

[0028]

As described above, if a pair of paper feed rollers 7 'are provided, the skew of the sheet cannot be prevented by the above-described skew prevention technique (FIG. 15). A pair of paper feed rollers 7 ', 7' share a common drive shaft 7a.
This is because the sheet P1 is pressed at the same time, and the sheet P1 cannot be rotated even if the transport roller pairs 2 and 3 are reversed.

However, if the pair of paper feed rollers 7 ', 7' is mounted on separate drive shafts and the free rollers can be freely rotated independently when the pair of transport rollers 2, 3 is rotated in the reverse direction, the above-described configuration is possible. It is possible to prevent the paper from being skewed by the skew prevention technology (FIG. 15). However, when the pair of paper feed rollers 7 ', 7' are mounted on different drive shafts, the paper will be significantly skewed at the time of paper feed unless the two drive shafts are synchronized with each other. In order to form a free roller that can freely rotate independently at the time of reverse rotation, a clutch or the like is required, and the structure becomes extremely complicated.

Therefore, the pair of paper feed rollers 7 ', 7'
It is not advisable to attach them to separate drive shafts so as to be free rollers that can freely rotate independently when the transport rollers 2 and 3 rotate reversely.

On the other hand, the structure shown in FIG. 14, that is, a substantially idle D-shaped paper feed roller 10, and a movable idle roller 1 which can freely rotate independently of the paper feed roller 10.
According to the structure provided with No. 7, it is considered that the above-described skew prevention technology (FIG. 15) can be used. This is because, if the transport roller pair is rotated in reverse while the paper feed roller 10 is not pressing the paper, the paper may be rotated by rotating the idle roller 17 under load.

However, in the structure shown in FIG.
As described below, it is extremely difficult or impossible to smoothly rotate the sheet, that is, to smoothly perform the skew preventing operation.

In the structure shown in FIG. 14, when the paper feed roller 10 makes one rotation during the paper feed operation and becomes the state shown in FIG. 14 (the state in which the arc portion 10a does not press the separation pad 13),
The urging force F2 of the spring 18 of the movable idle roller 17
Than the biasing force F1 of the spring 14 of the separation pad 13.
Is set larger, so that the separation pad 13
The movable idle roller 17 is stopped in a state where the movable idle roller 17 is pushed up until the shaft 17a comes into contact with the upper end of the long groove 11a.

In this state, when the sheet P1 is to be rotated by rotating the pair of conveying rollers in reverse, the sheet P1 is biased by the urging force F1 of the spring 14 of the separation pad 13 at the rear.
As a result, an attempt is made to rotate while being pressed between the separation pad 13 and the movable idle roller 17.

However, the separation pad 13 presses the paper between the arc portion 10a of the paper feed roller 10 as described above to prevent the case where two or more papers are fed. The bias force F
1 is set relatively large (at least larger than the urging force F2 of the movable idle roller 17 as described above).

Therefore, the sheet P1 must be rotated with the rear part of the sheet P1 pinched by the relatively large urging force F1, so that the sheet P1 hardly rotates or does not rotate.

That is, with the structure shown in FIG. 14, it is extremely difficult or impossible to prevent skew of the sheet.

An object of the present invention is to solve the above-described problems and to provide a printer which uses a substantially D-shaped paper feed roller and a movable idle roller when viewed from the side, and which can smoothly prevent skew of paper. Is to provide.

[0039]

According to a first aspect of the present invention, there is provided a sheet feeder having a sheet feed tray for holding a plurality of sheets in a stacked state, an arc portion and a straight portion. A substantially D-shaped feed roller for feeding the sheet by rotating once during a sheet feeding operation and feeding the sheet by contacting the arc portion with the uppermost sheet of the plurality of sheets stacked on the sheet feeding tray; The paper feed roller is positioned in the rotation orbit of the arc portion of the paper feed roller, is urged toward the paper feed roller by the pad urging means, and presses the paper between the arc portion and the paper feed roller. And a separation pad for separating the sheet to be fed from the next sheet, and a roller urging means for generating an urging force smaller than the urging force of the pad urging means. Idle roller in contact with pad A pad regulating means separate from the idle roller for regulating the movement of the separation pad toward the paper feed roller when the separation pad does not pinch the paper between the arc portion of the paper feed roller; A conveyance roller pair for conveying the paper fed by the paper roller, and after the leading end of the paper has passed through the nip portion of the conveyance roller pair, and the separation pad is located between the paper feed roller and the arc. When the sheet is not being pressed, the transport roller pair is once reversed to align the leading edge of the sheet along the nip portion.

According to a second aspect of the present invention, in the printer according to the first aspect, the feeding tray is inclined.
A sheet feeding tray for holding sheets in an inclined state, wherein at least one pair of the sheet feeding rollers is provided.

[0041]

According to the first aspect of the present invention, the printer has a sheet feeding tray for holding a plurality of sheets in a stacked state, an arc portion and a linear portion, and rotates once during a sheet feeding operation to rotate the arc portion. A sheet feed roller having a substantially D-shape in side view for feeding the sheet by contacting the uppermost sheet of the plurality of sheets of paper stacked on the sheet, and a pad positioned in the rotation orbit of an arc portion of the sheet feed roller. A separation pad that is urged toward the paper feed roller by the urging means and squeezes the paper with the arc portion to separate the paper to be fed by the paper feed roller from the next paper; So that during the paper feeding operation,
Only the top sheet is fed from the feed tray.

After the uppermost sheet is fed, the arc portion of the feed roller does not contact the sheet, that is, the separation pad does not pinch the sheet between the sheet and the arc portion of the feed roller. However, since the idle roller is urged toward the separation pad by roller urging means for generating an urging force smaller than the urging force by the pad urging means and is in contact with the separation pad, the paper is The idle roller and the separation pad are in a state of being pinched.

According to this printer, when the separation pad does not pinch the sheet with the arc portion of the paper feed roller, the movement of the separation pad toward the paper feed roller is restricted.
Since the pad regulating means different from the idle roller is provided, the urging force of the pad urging means is received by the pad regulating means.

Therefore, the pinching force of the sheet is obtained by the roller urging means, and the urging force of the roller urging means is smaller than the urging force of the pad urging means. It is possible to reduce the size as compared with (FIG. 14).

In such a state, after the leading edge of the sheet has passed through the nip portion of the pair of conveying rollers, once the pair of conveying rollers reversely rotates, if the sheet is skewed, as described above, The timing at which the leading end passes through the nip portion of the pair of conveying rollers in the opposite direction differs in the width direction, and the conveying force of the pair of conveying rollers partially acts on the sheet in the width direction.

In such a situation, the rear portion of the sheet
Since the paper is squeezed with a relatively weak squeezing pressure between the idle roller and the separation pad, the paper smoothly rotates around the squeezing part, and as a result, the leading edge of the paper is aligned along the nip part of the transport roller pair. It will be.

Thereafter, the sheet can be transported straight by rotating the pair of transport rollers forward.

That is, according to the printer of the first aspect, the skew of the sheet can be prevented smoothly.

According to the printer of the present invention, since the feeding tray is inclined and the sheet is held in an inclined state, the installation area of the entire printer can be reduced.

Further, since at least one pair of paper feed rollers is provided, remarkable skew of the paper at the time of paper feeding is prevented, and thereafter, the skew of the paper is reduced in the same manner as the operation according to the first aspect. Removed.

Therefore, the configuration according to claim 1 is
This is particularly effective when the sheet feeding tray is inclined.

[0052]

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

FIG. 1 is a side view showing an essential part of an embodiment of a printer according to the present invention, FIG. 2 is a plan view schematically showing a partially omitted part, and FIG. 3 is a partially enlarged view of FIG. 4 is a cross-sectional view taken along the line IV-IV in FIG. 3, FIG. 5 is a partially omitted plan view, and FIG. 6 is a side view in which portions different from FIG. 3 are omitted.

In FIGS. 1 and 2, SF is a paper feeder incorporated in the printer, 2, 3 are a pair of transport rollers as in the prior art, 4 is a printing means, 5 and 6 are a pair of discharge rollers, 80 Is a paper guide including an upper guide 80a and a lower guide 80b.

Reference numeral 20 denotes a paper feed roller, as shown in FIG.

FIG. 3 is an enlarged view of the sheet feeding device SF, and FIG.
However, the sheet feeding device SF is actually incorporated in the printer in a state where a sheet feeding tray 31 and a hopper 30, which will be described later, are inclined as shown in FIG.

As shown in FIG. 3, the paper feed roller 20 is formed in a substantially D shape in side view having an arc portion 20a and a straight portion 20b, and at least the surface of the arc portion 20a and the surface of the straight portion 20b are formed. It is formed of a high friction material (for example, rubber). The paper feed roller 20 is fixed to a paper feed roller shaft 22 via a bush 21. That is, the feed roller 20 and the bush 21 cannot rotate with respect to the feed roller shaft 22. The paper feed roller shaft 22 is supported by a frame (not shown, the same applies hereinafter), and is driven by a driving means (not shown, the same applies hereinafter) to just one during the paper feeding operation.
It is designed to rotate only by rotation.

Reference numeral 30 denotes a hopper, and 31 denotes a paper feed tray.
The hopper 30 is rotatably attached to the frame by a shaft 32, and the sheet feed tray 31 is detachably fixed to the frame. Plural sheets of paper P are set on the hopper 30 and the paper feed tray 31 in an inclined stacked state as shown in FIG. The set paper P is aligned by the leading end Pa of the paper P contacting the back surface 52 of the separation pad holder 51 described later.

Reference numeral 40 denotes a subframe, and a hopper spring (compression spring) 33 is provided between the subframe 40 and the tip of the hopper 30 (see FIG. 5). Therefore, the hopper 30 is constantly urged by the hopper spring 33 in the clockwise direction in FIG. 3, that is, in the direction in which the sheet P comes into contact with the paper feed roller 20, but as shown in FIGS. Cam followers 34 are formed at both side ends (only one side end is shown in FIG. 5) of 30.
When the cam follower 34 comes into contact with a hopper cam 35 (only one is shown in FIG. 5) fixed to the paper feed roller shaft 22, the rotation thereof is restricted. Note that a pad 36 similar to a separation pad described later is provided on the top surface of the tip of the hopper 30.

3 to 5, reference numeral 50 denotes a separation pad, which is fixed to the separation pad holder 51. The separation pad 50 has a coefficient of friction with the sheet P
It is made of a material (for example, a material such as cork) having a coefficient of friction smaller than zero. 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 50 and the paper is μ2, and the friction coefficient between the papers is μ3, μ1>
μ2> μ3.

The separation pad holder 51 holds the separation pad 50
And a pair of arm portions 54 integrally formed therewith, and a pad support portion 53 to which is fixed. The sub-frame 40 is rotatably attached to the sub-frame 40 by the shaft 55.

A pad spring (compression spring) serving as a pad urging means is provided between the pad support 53 and the subframe 40.
56 are provided. Accordingly, the separation pad holder 51 is constantly urged by the pad spring 56 in the clockwise direction in FIG. 3, that is, in the direction in which the separation pad 50 is brought into contact with the paper feed roller 20, but as shown in FIG. A projection 57 is formed on one side of the pad holder 51, and the projection 57 contacts the pin 41, which is provided on the sub-frame 40, and serves as a pad regulating unit, whereby the rotation thereof is regulated. ing. Projection 57 is pin 4
In a state in which the separation pad 50 is in contact with the sheet feeding roller 1, the separation pad 50 is located in the rotation orbit of the circular arc portion 20a of the sheet feeding roller.

In FIGS. 3 and 4, reference numeral 60 denotes an idle roller, and 61 denotes an idle roller holder. Reference numeral 70 denotes a cover for the sheet feeding roller 20, which is attached to the sub-frame 40.

The idle roller holder 61 has a substantially ring shape having a hole 61a at its center. A shaft 63 is provided below one side surface of the idle roller holder 61, and the idle roller 60 is rotatably supported by the shaft 63.

As shown in FIG. 3, a pair of holes 61b, 61b are formed in the idle roller holder 61, and hooks 42, 42 provided in the sub-frame 40 are lightly fitted to the holes 61b, 61b. Thus, the idle roller holder 61 is attached to the sub-frame 40. Further, a pair of pins 61c, 61c is provided on the upper and lower sides of the other side of the idle roller holder 61, and the pins 61c, 61c are slidably fitted into the elongated holes 43, 43 formed in the sub-frame 40. It is jammed (see FIG. 4). Further, the feed roller shaft 22 is inserted through the hole 61a of the idle roller holder 61,
The diameter of the hole 61a is formed larger than the diameter of the paper feed roller shaft 22.

Therefore, the idle roller holder 61
Is slidable in the directions of arrows a1 and a2 in FIG. 3 by the pins 61c, 61c being guided by the long holes 43, 43.
0 can also be slid in the directions of arrows a1 and a2.

A spring receiving portion 64 is provided on an upper portion of one side surface of the idle roller holder 61.
Between the cover 4 and the cover 70, a roller spring (compression spring) 65 as roller biasing means is provided. Therefore,
The idle roller holder 61 is formed by a roller spring 65
Although it is always urged in the direction of arrow a1, the idle roller 60 comes into contact with the separation pad 50,
Its movement is regulated. The urging force of the roller spring 65 is set smaller than the urging force of the pad spring 56. Therefore, the idle roller 60 is
Is not pushed down.

On the other hand, a cam follower 66 is formed on the lower surface of the spring receiving portion 64, and this cam follower 66 is
By coming into contact with or separating from the cam 23 formed on the bush 21 described above, the idle roller holder 61 moves in the direction of the arrow a1 or a2, and the idle roller 60 also moves in the direction of the arrow a1 or a2. I have. That is, the idle roller retracting mechanism is constituted by the idle roller holder 61 and the cam 23, and the operation of the cam 23 causes the leading edge of the sheet to be fed to move between the separation pad 50 and the idle roller 60 as described later. When the idle roller 60 passes through the separation pad 5
0, and after the leading edge of the paper has passed between the separation pad 50 and the idle roller 60, before the contact between the arc portion 20a of the paper feed roller 20 and the separation pad 50 via the paper is released. The cam 23 is configured so that the idle roller 60 contacts the separation pad 50.

In FIG. 4, A indicates a paper passing range.

Next, the operation of the above-described printer will be sequentially described in a standby mode, a sheet feeding operation, a sheet skew feeding operation, and a printing operation.

<Standby> During standby, the cam follower 34 of the hopper 30 is in contact with the hopper cam 35 of the sheet feeding device SF, as indicated by the solid line in FIG.
The hopper 30 has been pushed down. Also,
As shown in FIG. 3, the paper feed roller 20 is
b is in a state of facing the paper P, and the paper feed roller 2
0 is not in contact with the paper P.

Therefore, in this state, the paper P can be easily set on the hopper 30 and the paper feed tray 31.

The separation pad holder 51 (that is, the separation pad 50) is urged clockwise in FIG. 3 by the pad spring 56. When the projection 57 comes into contact with the pin 41 as shown in FIG. The rotation is restricted and stopped at the position shown in FIG. Therefore, the urging force of the pad spring 56 does not act on the idle roller 60. At this time, the separation pad 50 is located in the rotation path of the circular arc portion 20a of the sheet feeding roller.

The cam 23 and the cam follower 66 of the idle roller holder 61 are not in contact with each other. Therefore, the idle roller 60 is in contact with the separation pad 50 by the biasing force of the roller spring 65.

<Sheet Feeding Operation> (i) In FIG. 3, the sheet feeding roller shaft 22 starts rotating clockwise. Therefore, the paper feed roller 20 and the cam 23 also start rotating.

(Ii) As shown in FIG. 7, when the paper feed roller 20 and the hopper cam 35 rotate together with the paper feed roller shaft 22 by a predetermined angle and the contact between the hopper cam 35 and the cam follower 34 of the hopper 30 is released, The hopper 30 is pushed up by the hopper spring 33, and the sheet P is also pushed up.
a.

(Iii) As the paper feed roller shaft 22 continues to rotate, as shown in FIG.
The sheet P1 is sent toward the separation pad 50 by the contact between the 0 arc portion 20a and the top sheet P1. At this time, the sheet P2 is fed together with the sheet P1 because the next sheet P2 is attracted to the sheet P1 by the action of static electricity or a frictional force acts between the sheet P1 and the sheet P2. However, the movement of the sheet P2 may be hindered by the leading end P2a of the sheet P2 abutting against the separation pad 50, and the sheet P2 may be temporarily separated from the sheet P1. Similarly, even if lower-order paper P3 or the like is to be sent, it can be separated in the same manner.

At this point (the point shown in FIG. 8), the slope 23a of the cam 23 comes into contact with the cam follower 66 of the idle roller holder 61.
1a has not yet reached the contact portion T between the idle roller 60 and the separation pad 50.

(Iv) As the paper feed roller shaft 22 continues to rotate, the paper feed roller 20 is rotated as shown in FIG.
Presses the separation pad 50 via the uppermost sheet P1. As a result, the separation pad 50 is pushed down in the direction of the arrow b1 against the urging force of the pad spring 56, and at the same time, the uppermost sheet P1 is sandwiched between the separation pad 50 and the arc portion 20a of the paper feed roller 20 by the urging force of the pad spring 56. Press. That is, the sheet P <b> 1 is sent while being pressed between the sheet feeding roller 20 and the separation pad 50. At this time, as described above, the sheet P2 may be likely to be sent together with the sheet P1, but as described above, the friction coefficient between the sheet feeding roller 20 and the sheet is μ1, and the separation pad 50 and the sheet are separated. Assuming that the friction coefficient between the papers is μ2 and the friction coefficient between the papers is μ3, μ1>μ2> μ3, so that the paper P1 and the paper P
2 is the arc portion 20a of the feed roller and the separation pad 5
0, the paper P2 is hindered from moving by the frictional force between the paper P2 and the separation pad 50, is secondarily separated from the paper P1, and only the paper P1 is fed. Becomes

At this time (the time shown in FIG. 9), the cam follower 66 of the idle roller holder 61
Thus, the cam 23 is pushed up by the inclined surface 23a and rides on the arc surface 23b of the cam 23. As a result, the idle roller 60 moves in the direction of arrow a2, and the separation pad 5
However, the leading edge P1a of the uppermost sheet P1 has not yet reached the contact portion T between the idle roller 60 and the separation pad 50 (see FIG. 8).

That is, when the leading edge P1a of the paper P1 to be fed passes between the separation pad 50 and the idle roller 60, the idle roller 60 must be already separated from the separation pad 50. Becomes

(V) As the paper feed roller shaft 22 continues to rotate, the paper P1 is further fed in a state where the paper P1 is nipped by the paper feed roller 20 and the separation pad 50 as shown in FIG.

At this point (the point shown in FIG. 10),
The cam follower 66 of the idle roller holder 61 is located at the end of the arc surface 23b of the cam 23.

(Vi) As the paper feed roller shaft 22 continues to rotate, the paper P1 is further fed in a state where the paper P1 is nipped by the paper feed roller 20 and the separation pad 50, as shown in FIG.

At this time (the time shown in FIG. 11), the cam follower 66 of the idle roller holder 61 slides down the other inclined surface 23 c of the cam 23, so that the idle roller 60 Abut. However, at this time, the arc portion 20a of the paper feed roller is still in contact with the separation pad 5 via the paper P1.
0 is pressed.

That is, the idle roller 60 comes into contact with the separation pad 50 before the contact between the arc portion 20a of the paper feed roller and the separation pad 50 via the sheet P1 is released.

(Vii) Further, the feed roller shaft 22 rotates (just rotates once), and as shown in FIG.
Is pushed down by the hopper cam 35 and returns to the standby state (the state shown in FIG. 3).

At this point, the sheet P1 is not completely removed from the sheet feeding device, and the rear portion of the sheet P1 is in contact with the separation pad 50 and the idle roller 60.
It is in a state of being pinched by T ′ (see FIG. 2).

<Skew Feeding Operation of Paper> When the paper feed roller shaft 22 rotates during the above-described paper feed operation, the transport roller pairs 2 and 3 shown in FIG. 1 also rotate forward (rotate in the paper transport direction).

The paper P1 fed by the rotation of the paper feed roller 20 is guided by the paper guide 80 and travels to the pair of transport rollers 2, 3.

When the paper feed roller 20 has just made one rotation, as shown by the phantom line in FIG.
a is in a state where it has slightly passed through the nip portion N of the pair of conveying rollers 2 and 3.

Thereafter, the conveying roller pairs 2 and 3 once reversely rotate (see the arrow direction in FIG. 1).

In the case where the sheet P1 is skewed as shown by the imaginary line in FIG. 2, when the pair of conveying rollers 2 and 3 reverses, the leading end P1a of the sheet reverses the nip portion N of the pair of conveying rollers 2 and 3. The timing of passing in the direction differs in the width direction. When the sheet P1 is skewed, for example, as shown by the imaginary line in FIG. 2, the leading end P1a1 on the upper side in FIG.
a2 will pass. That is, the transport force by the transport roller pairs 2 and 3 does not act on the upper end P1a1, but the transport force acts on the lower end P1a2.

In such a situation, the rear portion of the sheet is in contact with the separation pad 50 and the idle roller 60 at the contact portions T and T '.
Therefore, if the conveying force acts only on the leading end P1a2 on the lower side of the sheet,
One (upper in FIG. 2) contact portion T acts as a load on the sheet to be fed back. Therefore, the sheet P1
Rotates in the direction of arrow X1 in FIG. 2, and as a result, the leading edge P1a of the sheet is aligned along the nip portion N of the pair of conveying rollers 2, 3 as shown by the broken line in FIG. The idle roller 60 in the other contact portion T 'rotates according to the sheet rotating in the arrow X1 direction.

<Printing Operation> Thereafter, the conveying roller pairs 2 and 3
Rotates forward and the sheet P1 is transported straight, and the printing means 4
Is printed out by the discharge roller pairs 5 and 6.

Until the trailing edge of the sheet P1 passes through the contact portions T and T 'between the separation pad 50 and the idle roller 60, the sheet P1 receives a load at the contact portions T and T' (backward). Is transported by the transport rollers 2 and 3).

In this case, since the idle roller 60 is urged by the roller spring 65 toward the separation pad 50 and presses the sheet P1 with the separation pad 50, the idle roller 60 is once separated from the next sheet P2. The next sheet P2 is again attracted to the sheet P1 by the action of static electricity, or
1 and the paper P2 exert a frictional force,
Even if the sheet P2 is sent together with the sheet P1, this is prevented.

According to the printer described above, the following operation and effect can be obtained.

(A) A sheet feeding tray 31 for holding a plurality of sheets of paper P in a stacked state, an arc portion 20a and a straight portion 20b are provided. A substantially D-shaped paper feed roller 20 that feeds the sheet P1 by contacting the uppermost sheet P1 of the plurality of sheets P that has been formed, and the rotation path of the circular arc portion 20a of the sheet feed roller 20 The sheet P1 to be fed by the sheet feed roller 20 is moved to the next sheet P2 by being urged by the pad spring 56 toward the sheet feed roller 20 to squeeze the sheet with the arc portion 20a. And the separation pad 50 that separates the uppermost sheet P1 during the sheet feeding operation.

After the uppermost sheet P1 has been fed, as shown in FIG. 12, the arc portion 20a of the paper feed roller is not in contact with the sheet, that is, the separation pad 50 is in the arc portion of the paper feed roller. 20a, the sheet P1 is not pinched, but the idle roller 60 is
Is biased toward the separation pad 50 by a roller spring 65 that generates a biasing force smaller than that of the sheet P1, and the sheet P1 is pressed by the idle roller 60 and the separation pad 50 because the sheet P1 is in contact with the separation pad 50. State.

According to this printer, when the separation pad 50 does not pinch the sheet P1 with the arc portion 20a of the paper feed roller, the movement of the separation pad 50 toward the paper feed roller 20 is restricted. Since the pin 41 is provided as a pad restricting means different from the idle roller 60,
The urging force of the pad spring 56 is received by the pin 41.

Therefore, the squeezing force of the sheet P1 is obtained by the roller spring 65, and the urging force of the roller spring 65 is smaller than the urging force of the pad spring 56.
It is possible to make it smaller than 4).

In this embodiment, the idle roller 60 is urged toward the separation pad 50 to
Is configured to pinch the sheet P1 between
(1) Load (resistance) on paper fed backward during skew prevention operation
And (2) the next sheet P2 is attracted again by the action of static electricity to the sheet P1 once separated from the next sheet P2, or the sheet P1 and the sheet P2 The purpose is to prevent the paper P2 from being sent together with the paper P1 in the process of transporting the paper P1 by the transport rollers 2 and 3 due to the frictional force acting between them. Roller biasing means (in this case, roller spring 65) within an achievable range
Can be made as small as possible.

In the process of transporting the sheet P1 by the transport rollers 2 and 3, the nip pressure TF1 required to prevent the next sheet P2 from being sent together with the sheet P1, and the nip pressure TF1 applied to the sheet P1 Nipping pressure TF2 required to apply a load (resistance) to rotate the paper and nip pressure T between the pad and the paper feeding roller required to separate the pad during paper feeding.
Since there is a relationship of TF1 <TF2 <TF3 with F3, the biasing force of the roller biasing means (in this case, the roller spring 65) can be made as small as possible within a range where this relationship is satisfied. It is. In this embodiment, T
F1 = TF2 <TF3.

In the above state, after the leading edge of the sheet P1 has passed through the nip portion N of the pair of transport rollers 2, 3,
Once the pair of conveying rollers 2 and 3 rotate in the reverse direction, the rear portion of the sheet P1 is squeezed by the idle roller 60 and the separation pad 50 with the relatively weak squeezing force TF2. The paper P1 rotates smoothly around the pressure portion, and as a result, the leading end P1a of the paper P1 is aligned along the nip portion N of the pair of transport rollers 2, 3.

That is, according to this printer, it is possible to smoothly prevent skew of a sheet.

(B) Since the feed tray 31 is inclined as shown in FIG. 1 and the sheet is held in an inclined state, the installation area of the entire printer can be reduced.

Since a pair of paper feed rollers 20 are provided, remarkable skewing of the paper at the time of paper feeding is prevented, and thereafter, the skewing of the paper is removed in the same manner as in the above operation (a).

(C) As described above, according to the printer of this embodiment, the load applied to the uppermost sheet P1 after feeding the sheet P1 is smaller than that of the conventional apparatus (FIG. 14). Can be smaller.

In the conventional device, a relatively large urging force F1
In this case, the rear portion of the sheet P1 is pressed, so that the load on the pressing portion is large, and if the conveying rollers 2 and 3 cannot provide a sufficient conveying force to overcome the load, the sheet Feed accuracy is reduced,
There was a problem that the printing accuracy by the printing means 4 was reduced. Therefore, in the conventional apparatus, in order to obtain a conveying force enough to overcome the load, the conveying rollers 2 and
3, it is necessary to increase the paper holding pressure, and at the same time, a large driving force for driving the transport rollers 2, 3 is required. . There is also a problem that the transport rollers 2 and 3 are easily worn.

On the other hand, according to the printer of this embodiment, after the uppermost sheet P1 is fed,
Can be reduced as compared with the conventional apparatus (FIG. 14), so that the above-described problem can be solved, and the conveying rollers 2 and 3 can be driven with a relatively small driving force. Accuracy can also be improved.

(D) During the sheet feeding operation, the sheet feeding roller 20 rotates to feed the topmost sheet P1.
1a is an arc portion 20a of the feed roller 20 and the separation pad 50.
(See FIG. 9), if the idle roller 60 is in contact with the separation pad 50, the idle roller 60 has a resistance against the paper to be passed. Becomes

On the other hand, according to the printer of this embodiment, when the leading edge P1a of the paper P1 to be fed is going to pass between the separation pad and the idle roller, the idle roller 60 is moved to the separation pad 50. Since the retraction mechanism is provided to separate the paper P1
However, the idle roller 60 does not become a resistance.

Further, the retracting mechanism is provided for the leading end P of the sheet P1.
1a passes between the separation pad 50 and the idle roller 60, the arc portion 20a of the paper feed roller and the separation pad 50
The idle roller 60 is brought into contact with the separation pad 50 before the contact via the sheet P1 is released (see FIG. 11).
After the contact between the arc portion 20a of the sheet feeding roller and the separation pad 50 via the sheet P1 is released, the next sheet P2 is not sent together with the top sheet P1 (see FIG. 2). See FIG. 12).

(E) The retracting mechanism of the idle roller is provided on the paper feed roller shaft 22 and is operated by the cam 23 rotating with the shaft 22, so that the structure can be simplified. For example, a simple structure can be achieved as compared with a case where the structure is operated by a solenoid or the like.

As described above, one embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the present invention.

[0117]

According to the printer of the first aspect, the skew of the sheet can be prevented smoothly.

Further, according to the printer of the second aspect, the installation area of the entire printer can be reduced.

[0119]

[Brief description of the drawings]

FIG. 1 is a side view showing a main part of an embodiment of a printer according to the present invention.

FIG. 2 is a partially schematic plan view of the same.

FIG. 3 is a partially omitted side view partially seen through the partially enlarged view of FIG. 1;

FIG. 4 is a sectional view taken along line IV-IV in FIG. 3;

FIG. 5 is a partially omitted plan view.

FIG. 6 is a side view in which parts different from those in FIG. 3 are omitted.

FIG. 7 is an operation explanatory view.

FIG. 8 is an operation explanatory view.

FIG. 9 is an operation explanatory view.

FIG. 10 is an operation explanatory view.

FIG. 11 is an operation explanatory view.

FIG. 12 is an operation explanatory view.

FIG. 13 is an explanatory diagram of a conventional technique.

FIG. 14 is an explanatory diagram of a conventional technique.

FIG. 15 is an explanatory diagram of a conventional technique.

FIG. 16 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

 P sheet P1 Top sheet P2 Next sheet 2,3 Conveyor roller pair 20 Feed roller 20a Arc section 20b Straight section 23 Cam 30 Hopper 31 Feed tray 40 Subframe 41 Pin 50 Separation pad 56 Pad spring 60 Idle roller 61 Idle roller holder 65 Roller spring 66 Cam follower

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location B65H 5/06 B65H 5/06 A

Claims (2)

[Claims] A sheet feeding tray for holding a plurality of sheets in a stacked state, an arc portion and a straight portion, wherein the arc portion is stacked on the sheet feeding tray by one rotation during a sheet feeding operation. A substantially D-shaped feed roller for feeding the sheet by contacting the uppermost sheet of the plurality of sheets, and a pad urging means which is located in the rotation orbit of the arc portion of the sheet feed roller. A separation pad that is urged toward the paper feed roller to squeeze the paper between the arc portion and separates the paper to be fed by the paper feed roller from the next paper; Between the idle roller, which is urged toward the separation pad by roller urging means for generating an urging force smaller than the urging force of the urging means, and which comes into contact with the separation pad; Do not pinch the paper with A pad regulating means different from the idle roller, which regulates the movement of the separation pad toward the paper feed roller, and a transport roller pair for transporting the paper fed by the paper feed roller. After the leading end of the sheet has passed through the nip portion of the pair of conveying rollers, and when the separation pad is not pressing the sheet with the arc portion of the sheet feeding roller, the pair of conveying rollers is once rotated in the reverse direction to form the sheet. A printer wherein the leading ends are aligned along the nip portion. 2. The sheet feeding tray according to claim 1, wherein the sheet feeding tray is inclined, and is a sheet feeding tray for holding the sheet in an inclined state, and at least one pair of the sheet feeding rollers is provided. Printer.