JP3482988B2 - Multi-sheet feed prevention device for sheets - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for preventing multiple sheets from being fed.

[0002]

2. Description of the Related Art As a device for preventing the multi-sheet feeding of a sheet represented by a recording sheet, generally, a pickup roller pulls out the uppermost sheet in a stack portion onto a separation pad, and the second and subsequent sheets are fed. Only the first sheet of paper is pulled out to the paper feed roller by the pickup roller while being held by the friction of the separation pad.

However, even with such a separating means, in the case of paper having a high degree of smoothness such as a film or paper charged with static electricity, the papers may be strongly adhered to each other for separation. It also causes a problem that it is difficult and the friction with the separation pad impairs the paper feeding accuracy that affects the print quality.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and its object is to:
It is an object of the present invention to provide a new sheet multi-sheet feeding preventing device that can reliably separate closely attached sheets without impairing the sheet feeding accuracy.

[0005]

That is, in order to achieve the above-mentioned object, the present invention is of a type that separates the second and subsequent sheets by sliding the back surface of the sheet against a separation pad in the feeding process. In the sheet multi-feed preventing device, when the sheet feeding roller in contact with the sheet is on the lower side of the sheet feeding direction of the separating pad, the sheet feeding roller is separated from the sheet at the standby position lower than the separating pad when the sheet feeding is completed. Sometimes, a push-up member that displaces to the sheet push-up position above the separation pad is provided, while near the upper side of the separation pad in the sheet transport direction, the sheet feed roller separated from the sheet comes into contact with the sheet only when the feeding is completed. A pressing member for deforming the lever sheet into an upward concave shape is provided.

[0006]

With this structure, when the paper feed roller is separated from the separation pad, the sheet is lifted from the separation pad by the push-up member, and the push-down member is brought into contact with the sheet to form a concave shape upward. The second and subsequent sheets are peeled off from the uppermost sheet without load by bending the sheet.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. 1 to 5 show one embodiment of a multi-sheet feeding preventing apparatus which is one embodiment of the present invention applied to a printer, based on each operation.

First, an outline of this apparatus will be described. In the hopper 1 for stacking and stacking the recording sheets S,
In a state where the separation pad 3 for preventing multi-sheet feeding is constantly urged to the pickup roller side by a separation pad holder spring (not shown), in a portion located immediately below the truncated circle type pickup roller 6 in a state where it is loaded in the printer body. Installed.

On the other hand, on the printer body side, between the pickup roller 6 and the pinch roller 7, there is provided a push-up roller 11 that lifts the recording sheet S so as to float from the separation pad 3 , and also the pickup roller. 6 , sea
A push-down roller 20 that tracks the roller 6 and suppresses the floating of the recording sheet S is provided on the upstream side in the transport direction, and is configured to perform the operation described below by a drive mechanism described below. .

Reference numeral 4 in the drawing denotes a hopper plate for pressing the uppermost recording paper S1 against the pickup roller 6 by the push-up lever 5, and reference numeral 8 directs the recording paper S to the print head. The paper feed roller to supply is shown.

[0011] pushing up roller 11 described above is constructed as a unit 10 which operates the push-back member 1 3 integrally with,
As shown in FIG. 5, two guide grooves provided on the left and right side plates.
14 and 15 , the waiting position (FIG. 1) below the paper path L that connects the separation pad 3 and the nip portion A of the pinch roller 7 and the paper to lift the recording paper S from the separation pad 3. A push-up position (FIG. 2) at which the recording paper S is pushed up and a push-back member 13 that is pushed up above the path L.
Thus, the second and subsequent recording sheets S are displaced to the push-back position (FIG. 3) for pushing back.

That is, as shown in FIG. 5, this mechanism rotates the rhombus cam 17 around the fulcrum 17a around the fulcrum 17a by the arc-shaped rib 16a and the pin 16b which are rotated every time the recording sheet S is fed and protruded to the periphery. A push-up roller 11 which is driven by a swinging drive disk 16 and a diamond-shaped cam 17 and is guided by two guide grooves 14 and 15 and is provided at the upper end every time the recording paper S is fed.
Is configured by the push-back member 13 that is displaced from the waiting position to the push-up position and then to the push-back position.

On the other hand, the sheet of the pickup roller 6
A push-down roller 20 that pushes down the recording paper S toward the separation pad 3 on the hand side in the conveying direction is a separation lever 2 pivotally supported by a fulcrum shaft 21 and slidably in the longitudinal direction.
It is attached to the free end of No. 2 and is configured to move in the arrow direction shown in FIGS. 4 (a) to 4 (c) by the operation cam 26 acting on the lever 22.

[0014] That is, the separation lever 22, by fitting the long hole provided in the base end portion to the supporting point shaft 21, slidably in the longitudinal direction, mounted swingably pivot shaft 21 around In addition, the spring 2 fixed at one end to the fulcrum of the fixing member
In the state in which the urging force in the clockwise direction in the figure is constantly applied by 9, the two cam followers 23, 24 provided on this surface are provided on the arc-shaped cam surface 27 and the spot-shaped cam piece 28 provided on the adjacent operation cam 26. It is configured to come into contact with each other and make a predetermined movement.

On the other hand, the operation cam 26 for operating the separation lever 22 is configured to rotate at the same speed as the pickup roller 6 by being driven by the gear 25 of the pickup roller drive system, and a part of its peripheral surface is An arcuate cam surface 27 including a horizontal portion 27a that comes into contact with the inner cam follower 23 of the separating lever 22 and pulls up the lever 22 toward the fulcrum shaft 21 and an arcuate portion 27b for holding this position, and the separating lever 22 L 4A is provided with a spot-shaped cam piece 28 which comes into contact with the shaped cam follower 24 and rotates the separation lever 22 counterclockwise in the figure against the spring 29.
In the waiting state shown in FIG. 3, the L-shaped cam follower 2 that comes out of the spot-shaped cam piece 28 and turns counterclockwise to the full by the urging force of the spring 29, and contacts the spot-shaped cam piece 28 from this state.
4 via a horizontal part 2 4 a vertical 2 4 b rotated counterclockwise in the drawing, and致Ru the separating action just before shown in FIG. 4 (b),
The inner cam follower 23, which is in contact with the arcuate cam surface 27, pulls up from the horizontal portion 27a to the circumferential portion 27b to cause the push-down roller 20 at the leading end to follow the inner locus a, and further to separate as shown in FIG. 4 (c). In the operating position, the vertical portion 2 of the L-shaped cam follower 24 pressed by the spot-shaped cam piece 28.
After turning fully to the right through 4b, and further from here to move from the arcuate cam surface 27 to move from the inner locus a to the outer locus b, it is released from the spot-shaped cam piece 28 and urged by the spring 29. It is configured to return to the standby position of FIG.

Next, the separating operation and the feeding operation of the recording paper S by the apparatus thus constructed will be described with reference to FIGS.
An explanation will be given based on (b).

In the waiting state until the paper feed signal is input, the drive disk 16 is, as shown in FIG.
The rear end of the arc-shaped rib 16a in the rotation direction is attached to the diamond-shaped cam 17.
In this state, the shaft 18 held by the diamond-shaped cam 17 and the pin 13a of the push-back member 13 are respectively brought into contact with the regulating projection 17a of the first embodiment. As shown in FIG. 1A, the push-back member 13 is located at the right end of the first and second guide grooves 14 and 15, and is separated from the push-back member 13.
It is located below the paper path L connecting the pinch roller 7 and the nip portion A of the pinch roller 7.

On the other hand, as shown in FIG. 4 (a), the separation lever 22 located behind the pickup roller 6 is disengaged from the spot-shaped cam piece 28 and is reciprocated around the fulcrum shaft 21 by the urging force of the spring 29. It rotates clockwise and holds the pressing roller 20 at its tip at the non-contact position.

From this waiting state, the pickup roller 6 is rotated counterclockwise together with the print signal so that its one end 6a is brought into contact with the separation pad 3 (see FIG. 1).
(B)), The hopper plate 4 is pushed up by the push-up lever 5 to bring the uppermost recording sheet S1 into contact with the pickup roller 6 (FIG. 1 (c)).

When the uppermost recording paper S1 is sent out to the nip portion A between the paper feed roller 8 and the pinch roller 7 as the pickup roller 6 rotates, the second and subsequent recording papers sent out together with this recording paper S1. S2 is separated by friction with the separation pad 3, and only the recording paper S1 at the leading end hits the nip portion A to be skewed, and along with this, the hopper plate 4 is lowered by about 5 mm to load the recording paper S. It reduces and helps skew removal (Fig. 2 (a)).

On the other hand, at this point, the separation lever 22
In the transition process from FIG. 4 (a) to FIG. 4 (b), the horizontal portion 24 b of the L-shaped cam 24 is pressed by the rotating spot-shaped cam piece 28 to rotate around the fulcrum shaft 21 in the figure. Although it starts to turn counterclockwise, the pressing roller 20 at the leading end does not come into contact with the recording paper S at this point.

On the other hand, the uppermost recording sheet S1 is the nip portion A.
5B, the drive disk 16 rotates in the direction of the arrow in the figure to allow the pin 16b protruding from the rear edge of the drive disk 16 to enter the groove. Rotate the cam 17 clockwise in the drawing to move the cam 1
Push-back member 1 via a common shaft 18 held at the lower end of 7.
3 is guided by the inclined portion of the first guide groove 14 and rises upward, and the push-up roller 11 at the tip thereof is projected from the conveying surface of the recording sheet S1 (FIG. 2B).

Then, at the time point shown in FIG. 2C, the push-back member 1 guided by the two guide grooves 14, 15 is pushed.
3 whereas further pushing up the recording sheet S by the push-up roller 11 at the tip, lightly pinch the recording sheet S with the push-back member 1 3 arc end 6b of the front end edge 12 and the pickup roller 6.

On the other hand, during this time, the separation lever 22 is
As shown in (c), the vertical portion 24b of the L-shaped cam 24 is pushed by the spot-shaped cam piece 28 while being pushed up by the circumferential portion 27b, so that the vertical portion 24b is rotated counterclockwise in FIG. Then, the push-down roller 20 at the leading end is deeply abutted against the surface of the recording paper S in the vicinity of the separation pad 3 to bend the recording paper S in this portion upward in a largely concave shape.

As a result, even when the second recording sheet S2 is strongly adhered to the back surface of the uppermost recording sheet S1 due to static electricity or the like, two sheets are caused by the curved portion largely bent by the push-down roller 20. the tip of the eye and subsequent recording sheet S2 is caused to peel from the back of the recording sheet S1 in the uppermost, it is prevented its delivery by front edge 12 of the push-back member 1 3.

[0026] By subsequent rotation, as shown in FIG. 3 (a), while the pick-up roller 6 Yuku away from the separation pad 3, will push-back is guided on two guide grooves 14, 15 members 1 3 that The recording paper S1 is lifted from the separation pad 3 by the push-up roller 11 at the front end to remove the paper feed resistance that adversely affects recording and writing as much as possible.

Finally, the separation lever 22 which is disengaged from the arcuate cam surface 27 is displaced in the projecting direction, and the pressing roller 20 at the tip of the separating lever 22 presses the uppermost recording sheet S1 from above to stably pull out the recording sheet S1. aims while, by the push-back member 1 3 of the front edge 12 moves the second and subsequent recording sheet S2, which is separated in the direction of the hopper 1 back into the cassette (Fig. 3
(B)) A sheet feeding operation including a series of multi-sheet feeding preventing operations is ended.

The separating lever shown in FIG. 6 shows another embodiment of the present invention which is constructed so as to be able to cope with thick recording paper having strong elasticity.

The separating lever main body 32 includes an L-shaped cam portion 3
An arm 35 pivotally supporting the push-up roller 30 is pivotally supported by a pin 36 at a portion deviated from 4, and
The lever main body 32 and the weak spring 37 stretched on the other end of the arm 35 keep the linear state at all times, and the arm 35 can be displaced in the retracting direction when a large force is applied. It is a thing.

This separation lever presses the ordinary recording paper in the vicinity of the separation pad 3 so as to give it a large flexure, and presses the recording paper in the direction of the arrow in the figure for a strong recording paper. By retracting the roller 30, damage to the separation lever main body 32 or the recording paper is suppressed in advance.

[0031]

As described above, according to the present invention, the lower side of the separation pad is displaced to the standby position below the separation pad at the time of sheet feeding, and is separated when the sheet feeding roller is separated from the sheet. A push-up member that displaces to the sheet push-up position above the pad is provided, and near the upper side of the separation pad, the sheet feed roller comes into contact with the sheet only when it is separated from the sheet, and this is transformed into a concave upward shape. Since a pressing member is provided, the second and subsequent sheets that are strongly adhered by static electricity can be easily and reliably peeled from the uppermost sheet by deforming the sheet upwards into a concave shape, and separate it. By performing the sheet separation operation while pushing the sheet upward from the pad, it is possible to simultaneously remove the paper feeding load that adversely affects the print quality. That.

Moreover, since a contact surface for contacting the leading end of the sheet is provided at the tip of the pushing-up member and the pushing-up member is moved toward the stack portion of the sheet while being raised, a load is involved. It is possible to return the second and subsequent separated sheets to the stack section again by this leading edge, and to perform the next sheet feeding without any trouble.

Furthermore, when an abnormal pressing force is applied to the pressing member, a part of the pressing member is displaced in the retreat direction, so that the present invention can be applied to a sheet such as a thick cardboard having a strong elasticity without any trouble. You can

[Brief description of drawings]

FIG. 1A to FIG. 1C are views showing a recording sheet separating and feeding operation.

2 (a) to (c) are diagrams showing the subsequent same operation.

3 (a) and 3 (b) are diagrams showing a further subsequent operation of the same.

4A to 4C are diagrams showing respective movements of a push-down lever.

5 (a) and 5 (b) are diagrams showing each operation of the lifting member.

FIG. 6 is a view showing another embodiment of the push-down lever.

[Explanation of symbols]

1 Hopper 3 Separation Pad 6 Pickup Roller 8 Paper Feed Roller 11 Pushup Roller 12 Front Edge 13 Pushback Member 20 Pushdown Roller 22 Separation Lever

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Claims (3)

(57) [Claims] 1. A sheet feeding process using a sheet feeding roller,
In a multi-sheet feeding preventing device of a type in which the back surface of the sheet is slidably contacted with a separation pad to separate the second and subsequent sheets, a sheet feeding roller contacting the sheet is provided on the lower side of the separation pad in the sheet conveying direction. A push-up member is disposed at a standby position below the separation pad when a sheet is to be fed, and a push-up member that is displaced to a sheet push-up position above the separation pad at the end of sheet feeding from the sheet feeding roller separated from the sheet. A sheet is characterized in that a push-down member is provided in the vicinity of the upper side of the pad in the sheet conveying direction so as to come into contact with the sheet and deform the sheet upward into a concave shape only when the sheet feeding roller separated from the sheet has finished feeding. Multi-sheet feeding prevention device. 2. A front surface of the push-up member is provided with an abutting surface for abutting the leading end of the sheet, and the push-up member is raised at the end of sheet feeding of the sheet feeding roller separated from the sheet, and 2. The multi-sheet feeding preventing apparatus according to claim 1, further comprising means for displacing the sheet beyond the separation pad to the stack of sheets. 3. The multi-sheet feeding prevention according to claim 1, wherein a part of the pressing member is provided with a member that is displaced in the retreat direction by an abnormal pressure contact force when the pressing member contacts the sheet. apparatus.