JP2001247225A - Paper feeding device and printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper feeding device capable of stably feeding paper even in the case of handling printing paper for high printing quality without being influenced by the abrasion of a paper feeding roller. SOLUTION: A surface layer of a paper feeding roller 121 is formed of an elastic body of a high friction material, an extrusion roller 9 to extrude a surface layer part 122c corresponding to a feeding starting corner part 121c of the paper feeding roller 121 outward is provided inside of the surface layer and an action retreating mechanism 10 for bulging the surface layer part 122c of the feeding starting corner part by moving this extrusion roller 9 to an extruding position only at the time of paper feeding start when the feeding starting corner part 121c of the paper feeding roller 121 delivers a paper sheet on the top level is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Rotary paper feed rollers feed stacked paper (plain paper, coated paper, OHP (overhead projector) sheets, glossy paper, glossy film, and other cut sheets) one by one from the top. More particularly, the present invention relates to a sheet feeding device suitable for a printer or the like and a printer including the same.

[0002]

2. Description of the Related Art Conventionally, a single-turn type paper feed roller having a substantially D-shape in side view has been used to reduce the number of stacked paper sheets from the highest one by one.
As a sheet feeding device of a type that feeds out one sheet at a time, for example,
There is one disclosed in US Pat. No. 3,396,396.

FIG. 12 shows the configuration. That is, this paper feeder includes a paper feed roller 40 in which a shaft 40d is supported by a guide block 41, and a plurality of sheets P stacked on an internal stacking plate 42a. And a separation pad 43 mounted on a bracket 43a and positioned in the rotation orbit of the arc portion 40a of the paper feed roller 40.
And a spring 44 for urging the separation pad 43 in the direction of the paper feed roller shaft 40d along the guide 45. Reference numeral 46 denotes an idle roller rotatably mounted on the guide block 41, and reference numeral 47 denotes the guide block 4.
This is a movable idle roller in which a shaft 47a is movably attached to one long groove 41a. Movable idle roller 47
Is biased toward the separation pad 43 by the spring 48 and is in contact with the separation pad 43. The urging force F2 of the spring 48 is set smaller than the urging force F1 of the spring 44 of the separation pad 43 (that is, F1> F2).

[0004] During standby, as shown in FIG. 12, the linear portion 40b of the paper feed roller 40 is in a state of facing the paper P, and the paper feed roller 40 is not in contact with the paper P.
The urging force F2 of the spring 48 of the movable idle roller 47 is equal to the urging force F2 of the spring 44 of the separation pad 43.
Since it is set smaller than 1, the movable idle roller 47 is pushed up by the separation pad 43, and the shaft 47a is in contact with the upper end of the long groove 41a.

During the paper feeding operation, the paper feeding roller 40 rotates in the direction of the arrow, and its arc portion 40a comes into contact with the uppermost paper P1 of the paper P, so that the paper P1 faces the separation pad 43. 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 43 as follows, and only the uppermost sheet P1 is fed. That is,
When the leading end of the sheet P2 hits the separation pad 43, the movement of the sheet P2 is hindered, and the sheet P2 can be temporarily separated from the sheet P1.

The friction force between the arc portion 40a of the paper feed roller 40 and the paper P1 is f1, and the paper P2 and the separation pad 4
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 40 and the separation pad 43 are configured such that a relationship of f1>f2> f3 holds. Therefore, when the paper P1 and the paper P2 are pressed together by the arc portion 40a of the paper feed roller and the separation pad 43 as the paper feed roller 40 rotates, the paper P2
The movement of the sheet P is inhibited by the frictional force with the separation pad 43, so that the sheet P2 is secondarily separated from the sheet P1 and only the sheet P1 is fed. The separation pad 43 is
Since the feed roller 40 is positioned in the rotation orbit of the arc portion 40a, the arc portion 4a rotates to rotate the arc portion 4a.
However, since the movable idler roller 47 is urged toward the separation pad 43 by the spring 48, even if the separation pad 43 is pressed down, it comes into contact with the separation pad 43. The separating operation is performed.

As described above, in the paper feeding apparatus shown in FIG. 12, if the paper feeding roller 40 is assumed to be a circular paper feeding roller, the paper feeding roller 40 is always in pressure contact with the separation pad. While the difficulty of ease is overcome by using a D-shaped paper feed roller in side view, the next paper gradually enters the press contact portion between the paper feed roller and the separation pad, and the paper can be separated. The difficulty of disappearing,
This is overcome by providing the idle roller 46 and the movable idle roller 47.

[0009]

However, in a paper feeding apparatus using a D-shaped paper feeding roller, when viewed in the direction of rotation of the D-shaped paper feeding roller 40, a circular arc portion 40a extends from the end of the linear portion 40b. , The paper on the hopper is first taken in and sent by the corner 40c at the start end, and the contact area with the paper is small. For this reason, the corner 40c of the D-type feed roller 40
The effect of abrasion is large, and non-feeding will occur while the device is being used.

[0010] Although there is not much problem with plain paper,
In the case where the above-described paper feeding device is applied to a printer and high-quality printing paper provided with a photo-printed paper-based coating layer is handled, the paper dust is generated by the surface portion near the corner 40 c of the D-shaped paper feeding roller 40. That is, there is a problem that the paper adheres to the surface portion exemplified as the adhered area X in FIG. 12, and the adhered paper dust causes the D-type paper feed roller to slip, thereby reducing the paper feeding force.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems, and to provide a paper feeder which is not affected by abrasion of a paper feed roller and is capable of performing stable paper feed even when handling high-quality print paper. The present invention is to provide a printer equipped with the same.

[0012]

Means for Solving the Problems In order to achieve the above object, the present invention is configured as follows. According to the first aspect of the present invention, the circular arc portion of the single-rotation type paper feed roller having a substantially D shape in side view is brought into contact with the surface of the paper stacked on the hopper, and the papers are fed one by one from the topmost paper. In the feeding device of the feeding type, the surface layer of the paper feeding roller is formed of an elastic body made of a high friction material, and a surface layer portion corresponding to a feeding action start corner of the paper feeding roller is formed inside the surface layer. An extrusion roller for pushing outward is provided, and the extrusion roller is moved to the extrusion operation position only when the feed operation start corner of the paper feed roller feeds the uppermost sheet, and the feed roller is moved. An action retreat mechanism for swelling the surface layer portion of the action start corner is provided.

According to the first aspect of the present invention, when the paper feed roller starts feeding paper, that is, when the paper feed roller rotates and its feeding start corner comes to the position where the uppermost paper is fed out, The pushing roller moves to the pushing action position by the action of the action retracting mechanism, and the surface layer portion of the feed action start corner swells. As a result, in the sheet feeding roller, the area of the sum of the non-swelling portion and the extruded swelling portion of the feeding action start corner portion is in contact with the sheet, and the contact area is increased when viewed in the circumferential direction. Paper feeding is started in this state.

In other words, the feed action start corner of the paper feed roller contacts the paper surface with a very small area at the start of paper feed when viewed in the direction of rotation of the paper feed roller unless the extrusion roller swells. become. However, in the present invention, at this point, the pushing roller moves to the pushing action position and swells the surface layer portion (rubber layer portion) of the feed action start corner, so that the feed roller is viewed in the rotation direction. As a result, the contact area becomes longer only at the bulging portion, and the paper feed roller comes into contact with the paper surface in a larger area.

Therefore, according to this paper feeder, even if the feed operation start corner of the D-type paper feed roller is worn, the feed operation start corner of the D-type paper feed roller is further reduced (see FIG. 12). Even when the paper dust of the printing paper for high image quality adheres to the middle attachment area X) and the D-type paper feed roller easily slips, the top sheet moves relative to the next sheet, It is paid out reliably. If even a small amount of paper starts to move, then the frictional force between the uppermost paper to be fed and the next paper is changed from static to dynamic and becomes smaller. The uppermost sheet is reliably fed by the arc portion following the sheet.

According to a second aspect of the present invention, in the paper feeder according to the first aspect, rubber is used as the elastic body of the high friction material, and a surface layer of the paper feed roller is formed as a surface rubber layer. It is characterized by the following. According to the present invention, since rubber is used as the elastic body of the high friction material, the swelling of the surface layer by the extrusion roller can be easily realized.

According to a third aspect of the present invention, in the paper feeding device according to the first or second aspect, the action retracting mechanism includes a stationary cam provided in a paper feeding roller, and a stationary cam provided in the paper feeding roller. One end is engaged and driven, and the other end is provided with a driven lever that supports the pushing roller and rotates integrally with the sheet feeding roller.

According to this feature, the driven lever rotates around the stationary cam together with the paper feed roller. When the paper feed roller starts feeding, that is, the paper feed roller rotates,
When the feed operation start corner comes to a position where the uppermost sheet is fed, the operation retracting mechanism moves the extrusion roller to the extrusion operation position, and the surface layer (rubber layer) of the feed operation start corner expands. Put out. As a result, when the feed roller is viewed in the circumferential direction, the area of the sum of the non-swelling portion and the extruded swelling portion of the feed start corner comes into contact with the sheet, and the contact area is enlarged. To start paper feeding.

The stationary cam is formed as an eccentric cam. When the paper feed roller comes into contact with the uppermost sheet at the start of paper feeding, the base of the driven lever comes to the most protruded portion from the center of the eccentric cam. It is preferable to synchronize them.

According to a fourth aspect of the present invention, in the paper feeder according to the first or second aspect, the action retracting mechanism is provided in a paper feed roller and supports the pushing roller. A plunger for displacing the extruding roller to an operative position for expanding the surface layer portion and a non-operating position retracted therefrom; and energizing the plunger only when the paper feed roller starts feeding the paper. And an energizing circuit for changing the pushing roller from a non-operating position to an operating position.

According to this feature, the extruding roller is displaced by the electrically operated plunger between the working position where the surface layer portion (rubber layer portion) swells and the non-working position. The timing of the non-operation position can be easily adjusted to the rotation position of the sheet feeding roller. In particular, there is an advantage that the timing can be easily adjusted by adjusting later.

According to a fifth aspect of the present invention, in the paper feeder according to any one of the first to fourth aspects, the surface layer portion of the feed start corner in the paper feed roller is formed by: It is characterized in that it is formed as a tongue that can be pushed outward in the radial direction, and the tongue comes into contact with the paper surface of the paper on the hopper when the paper feed roller starts feeding paper.

In the form in which the surface layer (rubber layer) of the corner for starting the feeding action is simply swollen by an extrusion roller, only one side of the chevron is an effective area that comes into contact with the sheet at the start of feeding. In the case where the surface layer portion (rubber layer portion) of the feed start corner is formed as a tongue extruded radially outward as described above, the tongue is rotated rearward in the rotational direction from the point where the extrusion roller is in contact with the tongue. The surface layer portion (rubber layer portion) is also an effective area in contact with the sheet at the same time as the start of sheet feeding and performing a feeding action. For this reason, in the sheet feeding roller, the sum area of the non-swelling portion of the feeding action start corner portion and the extruded swelling portion (entire tongue piece) comes into contact with the sheet, and when viewed in the circumferential direction thereof, Paper feeding is started in a state where the area is enlarged.

Further, according to the invention as set forth in claim 6 of the present invention, a sheet is sent out from a sheet feeding device, a predetermined printing is executed on the sheet by a printing section, and the sheet passing through the printing section is discharged by a sheet discharging section. In a printer configured to discharge paper to the outside, the paper feeding device is the one described in any one of claims 1 to 5.

According to the printer of the present invention, even when the feed operation start corner of the D-type paper feed roller is worn, it is further improved in the vicinity of the feed operation start corner of the D-type paper feed roller (see FIG. 12). Even if the paper dust of the high-quality printing paper adheres to the attachment area X), the D-type paper feed roller is likely to slip, the top sheet moves relative to the next sheet, and it is ensured. It is paid out. If even a small amount of paper starts to move, then the frictional force between the uppermost paper to be fed and the next paper is changed from static to dynamic and becomes smaller. The uppermost sheet is reliably fed by the arc portion following the sheet, so that printing can be executed under a stable sheet feeding state.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on the illustrated embodiment. First, the overall configuration will be described based on a partially omitted side view (partially transparent) showing the printer shown in FIG. As shown in FIG. 10, the sheet feeding device SF is rotatably attached to a pair of sheet feeding roller units 120 and 120 ′ attached to a sheet feeding roller shaft 110 and a frame (not shown). Hopper 130.

In FIG. 10, reference numeral 121 denotes a paper feed roller which is a component of the paper feed roller units 120 and 120 '. The paper feed roller has an arc portion 121a and a linear portion 121.
b and is substantially D-shaped in side view. And
When viewed in the rotation direction of the paper feed roller 121, the linear portion 121
The corner from the end of b to the starting end of the circular arc portion 121a acts as the feeding action start corner portion 121c.
Further, at least the surface of the arc portion 121a and the surface of the linear portion 121b of the sheet feeding roller 121 are formed of an elastic body (for example, rubber) of a high friction material. This paper feed roller 12
1 is fixed to a hollow paper feed roller shaft 110 rotatably fitted to the stationary shaft 100. Paper feed roller shaft 110
Although not shown, through a gear fixed to its shaft end,
By the electric motor as the driving means, just one
It is designed to rotate only by rotation.

The hopper 130 is rotatably attached to a frame (not shown) by a shaft 132. Reference numeral 137 denotes a paper feed tray, and the paper feed tray 13
Reference numeral 7 is attached to the printer. These hoppers 1
A plurality of sheets P are set in a stacked state on the sheet feeding tray 30 and the sheet feeding tray 137. The set sheet P is supported and aligned by its leading end contacting the back surface (support surface) 152 of the separation pad holder 151 described later.

Reference numeral 140 denotes a frame (hereinafter, referred to as a sub-frame) of the sheet feeding roller unit 120. A hopper spring (compression spring) 133 is provided between the sub-frame 140 and the tip of the hopper 130. The hopper 130 is constantly urged by the hopper spring 133 in the clockwise direction in FIG. However, the rotation is performed by the hopper cam 135 fixed to the paper feed roller shaft 110.
11 (see FIG. 11), the cam followers provided at both ends of the hopper 130 come into contact with each other, whereby the hopper 130 is regulated.

The separation pad 150 is fixed to the separation pad holder 151. The separation pad 150 is made of a material (for example, a material such as cork) whose friction coefficient with respect to the paper P is smaller than the friction coefficient of the paper feed roller 121. Each of the friction coefficients is made of a material having a friction coefficient larger than the friction coefficient between sheets. That is, the coefficient of friction between the paper feed roller 121 and the paper is μ1,
Assuming that the friction coefficient between the separation pad 150 and the paper is μ2 and the friction coefficient between the papers is μ3, μ1>μ2> μ3.

The separation pad holder 151 includes a pad support 153 (FIG. 11) to which the separation pad 150 is fixed.
It has the above-described support surface (rear surface) 152 at the leading end of the sheet and an arm 154 formed integrally therewith. The rear end of the arm 154 is rotatable by the shaft 155 to the sub-frame 140. Installed. The separation pad holder 15 is formed by a pad spring 156 provided between the lower surface of the pad support 153 and the subframe 140.
1 is a clockwise direction in FIG.
0 is constantly urged in the direction in which it contacts the paper feed roller 121.

Such a paper feeder SF is incorporated in a printer as shown in FIG. In FIG. 10, reference numerals 2 and 3 denote transport roller pairs for transporting paper, reference numeral 4 denotes a print head for printing on paper, reference numerals 5 and 6 denote paper discharge roller pairs for discharging printed paper, and reference numerals 8a and 8b denote paper. It is a guide. The hopper 130 is inclined as shown, and a plurality of sheets of paper P are set thereon in a stacked state.

Next, the operation of the above-described paper feeder will be described. During standby, the hopper cam 135
The hopper 130 has been pushed down. The paper feed roller 121 is in a state where the linear portion 121b faces the paper P, and the paper feed roller 121 is not in contact with the paper P. The separation pad holder 151 (that is, the separation pad 150) is moved by the pad spring 156 in FIG.
Is rotated clockwise, but by contacting a pin (not shown), its rotation is regulated and stopped at the position shown in FIG. Therefore, the pad spring 156
Does not act on the idle roller 160.
At this time, the separation pad 150 is located in the rotation orbit of the circular arc portion 121a of the sheet feeding roller. The idle roller 160 separates the separation pad 1 by the urging force of the roller spring.
It is in contact with 50.

Next, the operation during paper feeding will be described. (I) In FIG. 11, the paper feed roller shaft 110 starts rotating clockwise. Therefore, the paper feed roller 121,
The bush 142 and the hopper cam 135 also start rotating.

(Ii) As shown in FIG. 11, together with the feed roller shaft 110, the feed roller 121 and the hopper cam 1
The hopper cam 135 leaves the cam follower 134 of the hopper 130 by rotating the 35 by a predetermined angle. Thereby, the cam follower 1 of the hopper cam 135 and the hopper 130
When the contact with the sheet 34 is released, the hopper 130 is momentarily pushed up by the hopper spring 133 (FIG. 10), and the sheet P is also pushed up. Pressed. At this time, when viewed in the rotation direction, the feed roller 121 contacts the top end sheet P1 from the end of the linear portion 121b to the corner of the start end of the arc portion 121a (feed action start corner) 121c.

(Iii) Further, as the paper feed roller shaft 110 continues to rotate, the arc portion 121 of the paper feed roller 121 is rotated.
The sheet P1 is sent toward the separation pad 150 by rotating while contacting the uppermost sheet P1 with the sheet a. 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. Paper P
2 can be separated from the sheet P1 temporarily, because its tip is abutted against the separation pad 150 to hinder its movement.

(Iv) Further, as the paper feed roller shaft 110 continues to rotate, the arc portion 121a of the paper feed roller 121
Presses the separation pad 150 via the uppermost sheet P1. Thereby, the separation pad 150 is pushed down,
The uppermost sheet P <b> 1 is pressed between the sheet feeding roller 121 and the arc portion 121 a by the urging force of the pad spring 156.
That is, the sheet P1 is fed by the sheet feeding roller 121 and the separation pad 1
It is sent in a state where it is clamped between 50 and 50. At this time, as described above, the next paper P2 may be likely to be sent together with the paper P1, but as described above, the friction coefficient between the paper feed roller 121 and the paper is μ1, and the separation pad 150 is Assuming that the friction coefficient between the paper P and the paper P is μ2 and the friction coefficient between the papers is μ3, μ1>μ2> μ3, so that both the paper P1 and the paper P2 When the paper P2 is sandwiched between the arc portion 121a and the separation pad 150, the movement of the paper P2 is hindered by the frictional force between the paper P2 and the separation pad 150, and the paper P2 is secondarily separated from the paper P1 and is separated from the paper P1. Only will be fed.

At this time, the cam follower 166 of the idle roller holder 161 is in a state of riding on the arc surface 123b of the cam 123 formed on the bush 142. As a result, the idle roller 160 moves upward and is separated from the separation pad 150. That is, the leading edge of the sheet P1 to be fed is
When passing between the zero and the idle roller 160, the idle roller 160 is already separated from the separation pad 150. Note that the leading end of the uppermost sheet P1 has not yet reached the contact portion T (see FIG. 11) between the idle roller 160 and the separation pad 150.

(V) As the paper feed roller shaft 110 continues to rotate, the paper P1 is further fed in a state where the paper P1 is nipped by the paper feed roller 121 and the separation pad 150. At this point, the cam follower 166 of the idle roller holder 161 is located near the end of the arc surface 123b of the cam 123.

(Vi) As the paper feed roller shaft 110 continues to rotate, the paper P1 is further fed in a state where the paper P1 is nipped by the paper feed roller 121 and the separation pad 150.

At this point, the cam follower 166
The idle roller 160 comes into contact with the separation pad 150 by sliding down the other inclined surface 123c of the cam 123. However, at this point, the arc portion 121a of the paper feed roller 121 still presses the separation pad 150 via the paper P1. In other words, the idle roller 160 contacts the separation pad 150 before the contact between the arc portion 121a of the sheet feeding roller 121 and the separation pad 150 via the sheet P1 is released. The hopper 130 is pushed down by the hopper cam 135.

(Vii) Further, the feed roller shaft 110 rotates (just rotates once), and the hopper 130
At 35, it is completely depressed and returns to the standby state (FIG. 10). However, at this point, the sheet P1 is not completely removed from the sheet feeding device. Therefore, paper P
1 has a separation pad 150 and an idle roller 1 at its rear end.
Until passing through the contact portion T with 60, the load is applied to the contact portion T (pulled backward).
It is conveyed by the conveying rollers 2 and 3 shown in FIG.

In this case, since the idle roller 160 nips the sheet P1 with the separation pad 150, the next sheet P2, which has already been separated from the sheet P1, tries to descend by its own weight, or Even if the sheet P1 is attracted to the sheet P1 by the action of static electricity or is fed together with the sheet P1 by a frictional force with the sheet P1, this is prevented.

(Viii) After the trailing end of the sheet P1 fed and conveyed as described above comes off the sheet feeding device, the sheet feeding operation is performed again as necessary. However, in a sheet feeding device using a D-type sheet feeding roller, the D
When viewed in the rotation direction of the sheet feed roller 121,
The paper on the hopper is first taken in and fed by the feeding action start corner 121c from the end of 1b to the beginning of the arc 121a, and the contact area with the paper is small. For this reason, the influence of the abrasion of the feed operation start corner portion 121c of the D-type paper feed roller 121 is large, and non-feeding occurs while the use is continued.

Although there is no problem with plain paper, when handling high-quality printing paper provided with a photo-printing paper-based coating layer, the paper dust is fed by the D-type feeding roller 121 at the feed start corner. The surface portion near the portion 121c (FIG. 12)
There is a problem that the D-type paper feed roller 121 slips due to the paper dust adhered to the adhesion region X) shown in the drawing, and the paper feeding force is reduced.

Therefore, in the present invention, the feed action start corner portion 121 of the one-rotation type paper feed roller 121 having a substantially D shape in side view is provided.
c and the circular arc portion 121a are sequentially brought into contact with the surface of the paper stacked on the hopper 130, and the paper P is fed out one by one from the uppermost paper P1 and sent out. As shown in FIG.
21 is formed of an elastic body made of a high friction material, and a portion of the surface layer 122 corresponding to the feeding action start corner 121c of the paper feed roller 121 is directed inside the surface layer 122. The extrusion roller 9 is provided for extruding, and the extrusion roller 9 is moved to the extruding operation position only when the feeding operation start corner 121c of the paper feeding roller 121 starts feeding the uppermost sheet P1.
An action retreat mechanism 10 for swelling the surface layer 122 of the feed action start corner 121c is provided.

(Embodiment 1) A first embodiment of the action retracting mechanism will be described with reference to FIGS. FIG. 1 is a cross-sectional view in a direction orthogonal to a paper feed roller axis of a paper feed device according to a first embodiment of the present invention, and corresponds to a cross-sectional view taken along line II of FIG. 2, and FIG. FIG. 3 is a cross-sectional view taken along a feed roller shaft of the sheet feeder, and FIG. 3 is a perspective view of the sheet feeder according to the embodiment with a part cut away. FIG. 4 is a time chart for explaining the operation of the sheet feeding apparatus according to the embodiment.

1 to 3, reference numeral 121 denotes a substantially D-shaped paper feed roller having a circular arc portion 121a and a linear portion 121b, and the linear portion viewed from the rotation direction of the paper feed roller 121. A corner from the end of 121b to the start of the arc 121a acts as a feed action start corner 121c. The paper feed roller 121 includes a hollow inner shell layer 124 and a surface layer 122. The surface layer 122 is formed of an elastic body of a high friction material, here, rubber.

The feed roller 121 is fixed to the hollow feed roller shaft 110 rotatably fitted to the stationary shaft 100 as described above.
Although not shown in the drawing, is rotated just one rotation during the sheet feeding operation by an electric motor as a driving means via a gear fixed to the shaft end.

The hollow inner shell layer 124 is open at the portion corresponding to the action start corner 121c, which is the corner of the D-shaped paper feed roller 121, so that the paper feed roller shaft 11
A slit-like opening 125 running in the direction of 0 is formed. Therefore, in the rubber surface layer (hereinafter referred to as a rubber surface layer) 122, only a portion corresponding to the action start corner portion 121c is present as a single layer, and the other arc portions 121a and the linear portions 121b are not provided. It exists in the form of a double layer covering the surface of the inner shell layer 124.

In the paper feed roller 121, a surface layer portion 122 c corresponding to the feed action start corner 121 c of the paper feed roller 121 is pushed out from the inside to the outside in order to push it out. The extrusion roller 9 is disposed so as to face the slit-shaped opening 125.

Further, in the paper feeding roller 121, an operation retracting mechanism 10 for moving the extrusion roller 9 to the extruding operation position only at the start of paper feeding is integrated with the stationary shaft 100 penetrating through the paper feeding roller 121. The stationary cam 11 is fixed to the stationary cam 11, and the stationary shaft 10
The cam groove 12 is provided so as to surround 0 and to be eccentric upward (in a direction away from the paper P).

In the paper feed roller 121, there is provided a driven lever 15 which is engaged with and driven by a base 15a at one end serving as a cam follower in the cam groove 12, and has a tip end 15b at the other end provided with a pushing roller 9a. Are rotatably supported. An intermediate portion of the driven lever 15 is slidably supported in the axial direction by a guide 13 protruding inside the side wall of the sheet feeding roller 121.
Normally, the pushing roller 9 is urged in a direction to return the pushing roller 9 to the retracted position by the return spring 16 provided therebetween.

As described above, the action retracting mechanism 10 according to this embodiment includes the stationary cam 11 provided in the paper feed roller 121.
The base 15a is engaged with the stationary cam 11 to be driven, and the extruding roller 9 is supported at the tip 15b.
1 and a driven lever 15 that rotates integrally.

Next, the operation of the action retracting mechanism 10 will be described. In the action retracting mechanism 10 having the above-described configuration, when the sheet feeding roller shaft 110 rotates, the feeding action start corner 121c of the sheet feeding roller 121 comes into contact with the sheet P, and the sheet feeding is started to feed out the uppermost sheet P1 (see FIG. 4 time t1)
In FIG. 1, as shown in FIGS.
The base 15a of No. 5 is engaged with the large-diameter portion having the largest radial distance from the center of the cam groove 12. Therefore, the pushing roller 9 moves to the pushing action position, and the rubber surface layer portion 122c of the feed action start corner portion 121c swells as shown in FIGS.

As a result, in the sheet feeding roller 121, the sum of the non-swelling portion of the feeding action start corner portion and the extruded swelling portion elastically contacts the sheet P, and the circumferential direction thereof As described above, the sheet feeding is started in a state where the contact area is enlarged.

That is, when the feeding operation start corner portion 121c of the paper feed roller 121 does not swell by the pushing roller 9, the paper feed roller 121 has a very small area in the rotation direction of the paper feed roller 121 when the paper feed is started. Will come into contact with the surface. However, in the present embodiment, at the time of the start of the sheet feeding, the pushing roller 9 moves to the pushing action position to bulge the rubber surface layer portion 122c of the feed action start corner. For this reason, the contact with the sheet at the start of the sheet feeding is determined by the linear portion 121 when viewed in the rotation direction of the sheet feeding roller 121.
not only the corner from the end of b to the start of the arc 121a,
When the corner comes into contact with the paper, the paper is moved in the area in the circumferential direction following the corner which is also in contact with the paper at the same time, that is, in the area up to the rubber surface layer additionally swelled by the extrusion roller 9. Will be In other words, the swelled rubber surface layer portion 122c is present on a tangent passing through the corner (121c) of the paper feed roller 121.

Therefore, the distance from the end of the linear portion 121b to the top of the bulging portion (122c), that is, the effective contact length that exhibits an effective feeding action to the paper at the start of paper feeding, has no bulging portion. As compared with the case, the contact area viewed in the circumferential direction becomes longer accordingly, so that the paper feed roller 121 comes into contact with the paper surface with a larger area.

Therefore, even when the feed operation start corner portion 121c of the D-type paper feed roller 121 is worn, the feed operation start corner portion 1 of the D-type paper feed roller 121 is further reduced.
Even when the paper dust of the high-quality printing paper adheres to the vicinity of 21c (attachment area X in FIG. 12) and the D-type paper feed roller 121 easily slips, the bulging portion of the rubber surface layer portion 122c is not removed. Due to the presence, the uppermost sheet P1 relatively moves with respect to the next sheet, and is reliably fed out by several mm as shown in FIG. If even a small amount of paper starts to move, then the frictional force between the uppermost paper to be fed and the next paper is changed from static to dynamic and becomes smaller. Arc part 121 following part 121c
The uppermost sheet is reliably fed by a.

Next, when the paper feed roller shaft 110 is rotated and the paper is conveyed after the paper feed roller 121 feeds out the paper, the base 15 a of the driven lever 15 is at a greater radial distance from the center of the cam groove 12. The small diameter portion is engaged with the small diameter portion. Therefore, the base 15a of the driven lever 15 is
1 and moves upward from the position shown in FIG. Accordingly, the driven lever 15 moves upward while being guided by the guide 13 against the return spring 16, and does not bulge the rubber surface layer portion 122 c and is located at the retracted position inside the inner shell layer 124. Back. When the paper feed state is reached after the paper feed roller 121 has fed out the paper, the push-out roller 9 is returned to the retracted position inside the inner shell layer 124 by the action retracting mechanism 10, so that the normal paper supply is performed. It can be kept in the sending state.

Therefore, according to this paper feeding device, the paper feed roller 121 is not affected by the abrasion of the feed action start corner portion 121c, and is also affected by the adhesion of the paper dust even when handling high quality printing paper. And stable paper feeding can be performed.

(Embodiment 2) FIGS. 5 and 6 show a second embodiment of the present invention. This is feed roller 1
The surface layer portion 122 of the feeding action start corner portion 121 at 21 is partially or entirely formed as a tongue piece 17 that can be pushed outward in the radial direction, and the tongue piece 17 starts feeding of the feed roller 121. Sometimes, the paper comes into contact with the paper surface of the paper on the hopper. The configuration of the action retracting mechanism 10 is the same as that of the first embodiment, and is omitted from the drawing.

When the rubber surface layer portion 122c of the feeding action start corner portion 121c is formed as a tongue piece 17 to be pushed outward in the radial direction as in this embodiment, the pushing roller 9 of the tongue piece 17 is in contact with the tongue piece 17. The rubber surface layer portion B (FIG. 6) behind the point in the rotation direction is also an effective area that comes into contact with the sheet at the start of sheet feeding. Therefore, the feed roller 1
21 is a feed action start corner portion 1 when viewed in the rotation direction.
21c, a non-bulging portion followed by an extruded tongue 17
The paper is started in a state where the contact area is enlarged when the area of the sum of the contact area and the sheet comes into contact with the sheet and viewed in the circumferential direction.

(Embodiment 3) FIGS. 7 and 8 show a third embodiment of the present invention. This is a plunger provided in the paper feed roller 121 to constitute the action retracting mechanism 10, which supports the pushing roller 9,
A plunger 19 for displacing the extruding roller 9 between an operation position where the surface layer portion 122c of the feed operation start corner portion 121c bulges and a non-operation position retracted from the operation position.
And an energizing circuit for energizing the plunger only when the paper feeding roller 121 starts feeding and changing the pushing roller 9 from the non-operating position to the operating position.

In this embodiment, the plunger 19 is
A pair is provided in the paper feeding roller 121 at a distance corresponding to the length of the extrusion roller 9, and the movable elements inside each are installed so as to be vertically displaced. The extruding roller 9 is rotatably supported between the distal ends of the shaft portions 21 protruding downward from the movers of the plungers 19. The two shaft portions 21 are guided by a guide / spring stopper 22 projecting from the inner surface of the side wall of the sheet feeding roller 121, and are supported so as to be able to move up and down in the direction of the arrow shown in FIG.

On the other hand, a spring stopper 23 is provided on the shaft portion 21 of the mover of the plunger 19 at a position above the guide / spring stopper 22. A spring 24 is interposed between the spring stopper 22 and the spring stopper 23 to apply a biasing force to the push roller 9 in a direction approaching the sheet P. Note that a joint 25 is provided at the upper end of the mover. The power supply line 26 of the plunger 19 is connected to the hollow paper feed roller shaft 11.
0, and is connected to a power supply device through an energizing circuit (not shown).

Next, the operation of the action retracting mechanism 10 in the third embodiment will be described. Paper feed roller 121
Of the sheet P (see FIG. 1)
At the time of the paper feed start (time t1 in FIG. 9) in which the uppermost sheet P1 is fed in contact with the plunger 19, the plunger 19 is energized, the movable element is sucked, and the shaft portion 21 opposes the spring 24. And the extrusion roller 9 elastically contacts the uppermost sheet P1.

In order to ensure the contact timing of the pushing roller 9, in the case of this embodiment, as shown in FIG.
Plunger 19 is energized slightly earlier than time t1. In this specification, when the plunger 19 is energized only when the paper feed roller 121 starts feeding paper,
In this manner, a mode in which energization is slightly advanced is included.

When the feed operation start corner 121c of the paper feed roller 121 starts feeding the top sheet, the plunger 19 is energized and the plunger 19 is turned on.
The extrusion roller 9 is extruded downward in FIG. 7, whereby the rubber surface layer portion 122c is expanded.

Therefore, the contact area of the paper feed roller 121 with respect to the paper in the paper feed direction at the time of the paper feed start becomes longer, and the paper feed roller 121 feed operation start corner 121
Even if c slides with respect to the uppermost sheet P1 (see FIG. 1), the uppermost sheet P1 is always fed out by the feeding force of the pushing roller 9 and starts moving. If the paper starts to move even a little, then the frictional force between the uppermost paper P1 to be fed and the next paper changes from static to dynamic and becomes smaller. Paper is fed reliably.

Next, when the paper feed roller shaft 110 is rotated and the paper is conveyed after the paper feed roller 121 feeds out the paper, the power supply to the plunger 19 is turned off, and the return force of the spring 23 causes the push roller to return. 9 is brought back out of contact with the sheet P and to the retracted position inside the inner shell layer 124.

In the embodiment shown in FIG. 7, the pushing roller 9 is displaced between the working position and the non-working position by the plunger 19 which is electromagnetically operated. There is an advantage that it is possible to easily adjust to the rotational position by adjusting later.

[0073]

As described above, according to the present invention, when the paper feed roller starts feeding paper, that is, when the paper feed roller rotates, its feed start corner comes to the position where the uppermost paper is fed. Then, the push-out roller moves to the push-out action position by the action of the action retracting mechanism, and bulges a surface layer portion made of, for example, rubber, at the feed action start corner portion. The area of the sum of the swelled portion and the extruded swelled portion comes into contact with the sheet, and the sheet feeding is started in a state where the contact area is enlarged in the circumferential direction. In other words, the sheet is pressed not in a dot or line shape but in a sheet shape so as to increase the contact area only at the initial stage and fed.

Therefore, according to the paper feeder of the present invention, even if the feed operation start corner of the D-type paper feed roller is worn, furthermore, it is located near the feed operation start corner of the D-type paper feed roller. Even if the paper dust of the high-quality printing paper adheres and the D-type paper feed roller slips easily, the top sheet moves relative to the next sheet and is fed out reliably. If even a small amount of paper starts to move, then the frictional force between the uppermost paper to be fed and the next paper is changed from static to dynamic and becomes smaller. The uppermost sheet is reliably fed by the arc portion following the sheet.

In short, by feeding a small amount of feeding force to the paper at the start of paper feeding and performing auxiliary feeding, non-feeding of paper feeding by a D-shaped paper feeding roller with worn or paper dust is prevented, and Paper feeding capacity can be increased.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view in a direction orthogonal to a paper feed roller axis of a paper feed device according to a first embodiment of the present invention, and corresponds to a cross-sectional view taken along line II of FIG.

FIG. 2 is a cross-sectional view taken along a paper feed roller axis of the paper feed device according to the first embodiment of the present invention.

FIG. 3 is a partially cutaway perspective view of the sheet feeding device according to the first embodiment of the present invention.

FIG. 4 is a time chart for explaining the operation of the sheet feeding device according to the first embodiment of the present invention.

FIG. 5 is a perspective view illustrating an external appearance of a sheet feeding device according to a second embodiment of the present invention.

FIG. 6 is a schematic view showing a cross section of the sheet feeding device of FIG. 5;

FIG. 7 is a cross-sectional view illustrating a configuration of a sheet feeding device according to a third embodiment of the present invention.

FIG. 8 is a diagram illustrating a part of an action retracting mechanism of the sheet feeding device of FIG. 7;

FIG. 9 is a time chart for explaining the operation of the sheet feeding device of FIG. 7;

FIG. 10 is a view showing an example of attachment of the sheet feeding device of the present invention to a printer, and is a partially omitted side view partially seen through.

FIG. 11 is a diagram for explaining the basic operation of the sheet feeding device of FIG. 10;

FIG. 12 is a diagram illustrating a configuration of a conventional sheet feeding device.

[Explanation of symbols]

 Reference Signs List 9 Extrusion roller 10 Action retraction mechanism 11 Static cam 12 Cam groove 13 Guide 14 Stopper 15 Follower lever 15a Base 15b Tip 16 Return spring 17 Tongue 19 Plunger 21 Shaft 22 Guide and spring stopper 23 Spring stopper 24 Spring 25 Joint 100 Stationary shaft 110 Paper feed roller shaft 121 Paper feed roller 121a Arc portion 121b Linear portion 121c Feeding action start corner portion (corner portion) 122 Surface layer (rubber surface layer) 122c Surface layer portion 124 Inner shell layer 125 Opening 150 Separation pad P Paper P1 Top-level paper SF Paper feeder T Contact area X Adhesion area

Claims (6)

[Claims] 1. A feeding method in which an arc portion of a single-rotation type paper feed roller having a substantially D shape in side view is brought into contact with the surface of sheets stacked on a hopper, and the sheets are fed one by one from the uppermost sheet. In the paper device, a surface layer of the paper feed roller is formed of an elastic body of a high friction material, and a surface layer portion corresponding to a feed action start corner of the paper feed roller is directed outward inside the surface layer. A pushing roller for extruding the uppermost sheet is provided, and the pushing roller is moved to the pushing action position only when the feeding action start corner of the paper feed roller feeds out the uppermost sheet. A sheet feeding device provided with an action retracting mechanism for expanding a surface layer portion of the sheet feeding device. 2. The paper feeder according to claim 1, wherein rubber is used as the elastic body of the high friction material, and a surface layer of the paper feed roller is formed as a surface rubber layer. 3. The retraction mechanism according to claim 1, wherein the action retracting mechanism includes a stationary cam provided in a paper feed roller, one end of which engages with and is driven by the stationary cam, and the other end supports the pushing roller. And a driven lever that rotates integrally with the paper feed roller. 4. The operation retracting mechanism according to claim 1, wherein the action retracting mechanism is provided in a sheet feeding roller, supports the pushing roller, and causes the pushing roller to swell the surface layer portion. A plunger for displacing the plunger to the non-operating position retracted therefrom; and an energizing circuit for energizing the plunger only when the paper feeding roller starts feeding the paper and changing the pushing roller from the non-operating position to the operating position. A sheet feeding device, comprising: 5. The sheet feeding roller according to claim 1, wherein a surface layer portion of a feeding action start corner portion of the sheet feeding roller is formed as a tongue that can be pushed outward in a radial direction. A sheet feeding device, wherein the sheet feeding roller comes into contact with the sheet surface of the sheet on the hopper at the time of starting sheet feeding. 6. A printer having a configuration in which a sheet is sent out from a sheet feeding device, a predetermined printing is executed on the sheet by a printing unit, and the sheet passing through the printing unit is discharged to the outside by a discharge unit. The printer according to claim 1, wherein the sheet feeding device is the one described in claim 1.