JPH03128835A - Retard device of sheet feed mechanism - Google Patents

Abstract

PURPOSE:To ensure complete prevention of multiple sheet feed by making stronger return force than attaching force and frictional force between multiple- feed sheets by the return action of a retard member by stress accumulated when a driving roller and the retard member are driven. CONSTITUTION:If multiple-feed sheets by a sheet feed roller 5 are inserted in a nip part formed between a retard driving roller 6 and a retard roller 7, the driving force of the retard driving roller 6 will not work on the retard roller 7. Instead, the force accumulated in a coil spring 21 works on the sheet brought into contact with the retard roller 7. At this time, by setting the force accumulated in the coil spring 21 so that it may become larger than attaching force and frictional force between the multiple-feed sheets, it is possible to rotate the retard roller 7 in an opposite direction so that the sheet brought into contact with the retard roller 7 may be returned to the upstream side, thus providing the prevention of multiple sheet feed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a retard device for a paper feeding mechanism used to feed cut sheets to image forming apparatuses such as copying machines and printers.

[Prior Art] Generally, a paper feeding mechanism used for feeding cut sheets in an image forming apparatus such as a copying machine or a printer has a mechanism that separates cut sheets stacked in a paper feed cassette one by one. For feeding, a retard-type sheet separation and feeding mechanism is used, which includes a paper feed roller, a retard roller, and the like.

Next, a configuration example of a retard device used in a conventional retard type sheet separation and feeding mechanism will be described with reference to FIG. 9 and FIG. 1O. This configuration example is a paper feeding mechanism using a retard roller disclosed by the applicant in Japanese Patent Laid-Open No. 64-38346. In the figure, 101 is a paper feed cassette, and 102 is a sheet placement plate, one end of which is swingably attached around a support shaft 103.

The lower surface of the sheet placement plate 102 and the sheet cassette 10
A coil spring 104 is compressed and disposed between the bottom plate of the sheet mounting plate 1 and the bottom plate of the sheet mounting plate 1.
02 is always biased clockwise around the support shaft 103 to press the sheets stacked on the sheet placement plate 102 against the paper feed roller 105.

Reference numeral 106 denotes a retard roller that is placed against the paper feed roller 105 and is configured as shown in FIG. That is, the retard roller 106 is constructed by press-fitting a cylindrical rubber member 10B onto the outer periphery of a hollow plastic cylindrical member 107, and a groove 107a is formed in one end surface of the cylindrical member 107.

A torque spring 109 is fitted into the hollow portion of the cylindrical member 107 so as to tightly contact the inner wall thereof, and the end portion 109
a is adapted to engage with the groove 107a. Further, a retard shaft 110 is fitted into the inner periphery of the torque spring 109 so as to be in close contact with the inner periphery of the torque spring 109, and one end portion 110a thereof has a small diameter and the other end portion 110b is formed into an oval shape. 111 is a U-shaped holding member, with long holes 111 on both side plates.
By inserting the retard shaft 110 into the elongated hole 111a, the retard shaft 110 is prevented from rotating and is held so that it can move only in the length direction of the elongated hole 111a. In this manner, the retard roller 106 is held by the holding member 111 and the retard shaft 110 is pressed by the spring member 112 as shown in FIG. 6, so that the retard roller 106 is brought into pressure contact with the paper feed roller 105. .

The operation mode between the retard IdllIO and the retard roller 106 is such that a torque spring 109 is interposed between them and the spring 109 functions as a one-way constant torque clutch, so the retard roller 106 rotates only in one direction. I am unable to move. Furthermore, in the unfitted state, the inner diameter of the torque spring 109 and the outer diameter of the retard shaft 110 are slightly larger, so that when the retard roller 106 is rotated in one direction, the outer diameter of the retard shaft 110 is slightly larger. , the retard roller 106 can be rotated with a certain amount of torque, and in the state shown in FIG. ing.

In the paper feeding device configured in this way, the paper feeding roller 1
05 rotates, the retard roller 106 is rotated around the retard shaft 110. At this time, paper feed roller 1
05 turns the retard roller 106 as To,
Furthermore, the fitting torque between the retard shaft 110 and the torque spring 109, that is, the torque required to rotate the retard roller 106, is assumed to be T1. Then, the sheet is conveyed as the paper feed roller 105 rotates, and the retard roller 106 and the paper feed roller 1
05, rotational torque Tt is applied to the retard roller 106 by the paper. At this time, T
So that the relationship o > T + > T2 holds,
Since the friction coefficient and contact force of the paper feed roller 105 and the retard roller 106 are set, the retard roller 10
6 does not rotate. Therefore, the sheet is retard roller 1
06 and is conveyed by the paper feed roller 105.

A plurality of sheets are transferred to the retard roller 106 and the paper feed roller 10.
If the sheets are conveyed to the nip section 5 in an overlapping manner, the moment the sheets are nipped at the nip section, the drawer 106
stops rotating, and only the uppermost sheet is conveyed by the paper feed roller 105, and the other sheets are stopped by the braking action of the fitting torque T1 of the retard roller 106, thereby preventing double feeding.

[Problem to be solved by the invention]

By the way, in a conventional retard device using a retard roller that prevents co-rotation using a one-way clutch to prevent double feeding of sheets, if the adhesion force between the double fed sheets is a little strong, The sheet at the bottom surface is conveyed so as to slide on the retard roller, and it is not possible to prevent the conveyance of sheets other than the sheet at the top position, resulting in double feeding.

The present invention was made in order to solve the above-mentioned problems in conventional retard devices, and it applies a strong pullback force to sheets that are double-fed, thereby reliably preventing double-feeding even when the adhesion between sheets is strong. The purpose of the present invention is to provide a retard device that can perform the following functions.

[Means and operations for solving the problem] In order to solve the above problems, the present invention provides a retard device for a sheet feeding mechanism that elastically presses the drive roller to prevent double feeding of sheets. a retard member that is driven by rotation;
A means for accumulating elastic stress in accordance with the retard member is provided, and a pulling force is applied to the sheet in contact with the sheet by a returning operation of the retard member due to the stress accumulated in the stress accumulating means. It consists of

With this configuration, when double feeding of sheets occurs, the return action of the retard member due to the stress accumulated in the stress accumulating means reduces the adhesion force between the sheets that are in contact with the sheets. A pullback force greater than the frictional force acts, and it is possible to effectively prevent the conveyance of double-fed sheets.

〔Example〕

Next, an example will be described. FIG. 1 is a partially sectional plan view showing a state in which a first embodiment of the retard device according to the present invention is mounted on the main body side and combined with a paper feeding mechanism, and shows cut sheets loaded in a sheet cassette. This shows how the sheets are being fed one by one. In the figure, ■ is a sheet cassette, 2 is a sheet mounting plate that is swingably mounted with one end supported by a spindle, and 3 is a coil spring that pushes up the sheet mounting plate 2 onto the mounting plate 2. The sheet 4 placed on the paper feed roller 5 is pressed against the paper feed roller 5. Reference numeral 6 denotes a retard drive roller, which is integrated into a unit with the paper feed roller 5 and configured to be rotated simultaneously by a drive mechanism (not shown). 7 is a retard roller arranged so as to be in pressure contact with the retard drive roller 6.

FIG. 2 is an exploded view of the parts of the retard roller portion, and FIG. 3 is an assembled sectional view thereof. The retard roller 7 is constructed by press-fitting a cylindrical rubber roller 12 onto the outer periphery of a hollow roller core 11, and a groove 13 is formed at one end of the roller core 11 along its inner peripheral wall. , and the groove 1
A stopper 14 is formed in the portion where 3 is not formed. In addition, the inner circumferential wall on the other end side of the roller core 11 is made larger in diameter,
A support hole 16 for inserting and holding one end of a coil spring, which will be described later, is formed at the terminal end of the large-diameter inner circumferential wall portion 15.

This retard roller 7 has a hollow clutch shaft 1.
7 is rotatably inserted, a slot 18 is formed at one end of the clutch shaft 17, and clutch teeth 19 having a plurality of inclined surfaces are formed on the outer periphery of the other end, and the roller core 11 A stopper portion 20 that fits into the groove portion 13 and engages with the stopper 14 is formed.

As shown in FIG. 3, a coil spring 21 is disposed between the clutch shaft 17 and the large-diameter inner circumferential wall 15 of the roller core 11, and one end of the coil spring 21 is connected to the slot 18 of the clutch shaft 17 and the other end is connected to the roller core 11. It is inserted into the support hole 16 of the core 11 and held. Then, the stop plate 22 is fitted into the end of the slot 18 and fixed, and the peripheral part of the stop plate 22 is brought into contact with the end face of the roller core 11 to hold the clutch shaft 17 within the retard roller 7, and the retard roller 7 is held against the clutch shaft 17. It is designed to be able to rotate against the spring force of the coil spring 21 over the range in which the groove portion 13 is formed.

Next, the roller assembly thus formed is placed and held within the U-shaped support frame 25. A pin insertion hole 28 is formed in one side 26 of the plates 26 and 27 on both sides of the support frame 25, and a pin insertion hole 29 is formed in the side plate 27 on the side where the clutch teeth 19 of the clutch shaft 17 are disposed. A hole 30 and a notch 3 for inserting a locking piece 36 having an inclined surface attached to a circular spring plate 35 arranged on the outside of the
1. Further, hook portions 32,33 for support are formed in the extensions of each side plate 26,27 of the support frame 25, and a locking groove 34 is formed in the central upright piece.

Then, the circular spring plate 35 is engaged with the clutch tooth 19 of the clutch shaft 17 through the insertion hole 30 and the notch 31 of the support frame side plate 27 with its locking piece 36 so that the inclined surfaces thereof face each other, The circular spring plate 35. The pin 37 is inserted through the insertion hole 28.29 of the support frame side plate 26.27 and the hollow part of the clutch shaft 17, and the roller assembly is supported on the support frame 25 via the circular spring plate 35, and the retard roller portion is Configure.

As shown in FIG.
2.33 is fitted onto the support shaft 39 which is supported on the apparatus main body side and is biased to rotate by the spring 38, and mounted on the main body 1 side, and the bottle 4o protruding from the support shaft 39 is attached to the support frame 25. When engaged with the locking groove 34, the retard roller 7 is configured to be brought into pressure contact with the retard drive roller 6 as shown in FIG. And retard roller rough clutch shaft 17
cannot rotate in the sheet feeding direction due to the engagement between its clutch teeth 19 and the locking piece 36 of the circular spring plate 35, but in the opposite direction to the sheet feeding direction, the clutch teeth 19 are tilted. The surface engages with the inclined surface of the locking piece 36 of the circular spring plate 35, and the locking piece 36 held by the circular spring plate 35 is moved in the axial direction of the clutch shaft 17 due to the deformation of the spring plate 35. The clutch shaft 17 can be easily rotated to accommodate the ejection of jammed paper from the sheet cassette side.

Next, the operation of the retard device configured as described above will be explained. When the retard drive roller 6 starts rotating with the start of sheet feeding, the retard roller 7 that is in pressure contact with it rotates together with the retard drive roller 6.

On the other hand, the rotation of the clutch shaft 17 is stopped when the clutch teeth 19 provided at one end engage with two locking pieces 36 of the circular spring plate 35 supported by the support frame 25. The coil spring 21, whose other end is supported by the slot 18 of the clutch shaft 17, is wound tightly in the support hole 16 of the roller core 11, and a biasing force is accumulated. Then, when the retard roller 7 continues to rotate together and the stopper 14 provided on the roller core 11 comes into contact with the stopper portion 20 of the clutch shaft 17, the retard roller 7 stops rotating.

In such a state, when the multi-fed sheets fed by the paper feed roller 5 enter the nip formed between the retard drive roller 6 and the retard roller 7, the retard drive roller 6 The driving force stops working. Then, the biasing force stored in the coil spring 21 comes to act on the sheet that is in contact with the retard roller rough. At this time, by setting the accumulated biasing force of the coil spring 21 to be greater than the adhesion force and frictional force of the double-fed sheets, the sheets in contact with the retard roller 7 are retarded in the direction of pulling them back upstream. The rollers 7 are rotated in the opposite direction to prevent double feeding.

Note that even when a single sheet is fed by the paper feed roller 5, if the sheet enters the nip formed between the retard drive roller 6 and the retard roller 7, the retard roller 7 will rotate in the opposite direction. However, since the retard drive roller 6 continuously applies a large conveying force to the sheet, there is no problem in feeding the sheet. .

Next, a second embodiment of the present invention will be described based on FIG. This embodiment uses a retard pad as a retard member that comes into pressure contact with the retard drive roller, and the same members as those in the first embodiment shown in FIG. 1 are given the same reference numerals and their explanations will be omitted.

The retard pad 51 in this embodiment is slidably supported on a support plate 52, and a return spring 53 is stretched between one end of the retard pad 51 and an end 52a of the support plate 52.

A stopper 51a is formed protrudingly on the lower surface of the retard pad 51, and is inserted into a groove 52b formed in the support plate 52 and abuts one end of the groove 52b, thereby increasing the movement range of the retard pad 5I. are now regulated. Furthermore, the support plate 5
One end of the pressure spring 54 is fixed to the spring support/holding part 52c extending below the spring 2, and its free end is brought into contact with the lower surface of the retard pad 51 through the groove part 52b, so that the retard pad 51 is connected to the retard drive roller 6. It is designed to be pressed.

Next, the operation of the retard device with the bottom of the tank as described above will be explained. When the retard drive roller 6 starts rotating with the start of sheet feeding, the retard pad 51 pressed against it moves in the direction of the arrow, and the return spring 53 stretched at one end is stretched. Biasing force is accumulated. Then, as the retard pad 51 continues to follow and the stopper 51a abuts one end of the groove 52b of the support plate 52, the retard pad 51 stops being driven.

In such a state, when the multi-fed sheets fed by the paper feed roller 5 enter the nip formed between the retard drive roller 6 and the retard pad 51, the retard pad 51 has the retard drive roller 6. The driving force will no longer work. Then, attach the return spring 5 to the sheet that is in contact with the tart pad 51.
The biasing force accumulated in 3 begins to act. At this time, by setting the accumulated biasing force of the return spring 53 to be greater than the adhesive force and frictional force of the multi-feed sheets,
The retard pad 51 is returned in the direction of pulling back the sheets in contact with the retard pad 51 upstream, and double feeding is effectively prevented.

In each of the above embodiments, the retard roller 7 or the retard pad 51 driven by the rotation of the retard drive roller 6 is
After accumulating elastic stress by being driven by the retard drive roller 6, the stopper 14 of the groove 13 is locked to the stopper 20 of the clutch shaft 17, or the retard pad stopper 51a is moved to the groove 52 of the support plate 52.
In the above example, the rotation of the retard roller rough or the movement of the retard pad 51 is stopped by contacting one end of the retard roller rough, but it is possible to stop the movement of the retard drive roller 6 without particularly providing such a stopper member. The bottom of the tank may be configured to stop the rotation of the retard roller luff or the movement of the retard pad 51 by the reaction force of the spring whose stress is accumulated by the following action.

Next, a third embodiment of the present invention will be described.

Similar to the first and second embodiments, this embodiment prevents double feeding by applying a strong pullback force to sheets that are double fed, and also shifts the pressure contact portion of the retard roller by attaching/detaching the sheet cassette to create a new sheet. The retard roller is pressed against the retard drive roller, thereby prolonging the life of the retard roller, and the retard roller is supported so that its axis can swing, and the retard roller is evenly pressed against the retard drive roller, thereby preventing the skew of the sheet. This prevents uneven wear of the rows and rollers.

FIG. 6 shows a state in which a sheet cassette is attached to the retard device of this embodiment and the cut sheets loaded in the sheet cassette are fed one by one. The same reference numerals are given to the same or equivalent members as in the first embodiment. FIG. 7 is an exploded perspective view of the retard roller side of the retard device of this embodiment.
The figure shows an assembled sectional view of the retard roller portion. The retard roller 61 is formed by a roller core 63 integrally formed with the shaft portion 62 and a cylindrical rubber roller 64 press-fitted to the outer periphery of the roller core 63, and a notch 63a is formed at the inner side of one end of the roller core 63. has been done. Then, a press-fitting part 65a having a smaller diameter than the shaft part 62 is press-fitted into the shaft part 62, and
The press-fitting portion 65a of the coil spring 65, which is integrally formed with a slack portion 65b having a larger diameter than the shaft portion 62 that fits loosely with a gap, is press-fitted into the shaft portion 62 in the notch 63a. A coil spring 65 is disposed within the notch 63a. In the press-fit portion 65a of this coil spring 65,
It has a one-way clutch function.

And the shaft part 6 of the retard roller 61 which is at the bottom of the tank in this way
2 are fitted into notched bearings 67 formed on both side plates of a U-shaped support frame 66, and an E-ring 68 is fitted to hold the retard roller 61 within the support frame 66. One end of the slack portion 65b of the coil spring 65 press-fitted into the coil spring 62 is locked to the side plate of the support frame 66.

Further, the support frame 66 is provided with a cut-and-raised piece 69 at the center and a bent piece 70 on the end face between the side plates, and the central cut-and-raised piece 69 has a cutout groove 69 closed at the bent part.
a, and the bent piece 70 has a cutout groove 70 with one end open.
a are formed respectively. Then, on both ends 72a and 72b of a pin 72 provided in a direction perpendicular to the axial direction of a retard support shaft 71 supported by the device main body,
The notch grooves 69a and 70a of the support frame 66 are engaged with each other, and the retard support frame 66 is connected to the retard support shaft 71.
It is supported so as to be able to swing around a pin 72.

A frame-shaped bracket (c) 73 is fixed to one end of the retard support shaft 71, and the bracket (2) 73
An arm-shaped bracket (8174) is rotatably attached to the support shaft 71 so as to sandwich it therebetween.

A retard spring 75 is stretched between the tip of one arm 74a of the bracket (8174) and one end of the frame parallel to the support shaft 71 of the bracket 73, and the other arm 74b of the bracket 74 The flat end portion 74c of the sheet cassette l is adapted to come into contact with the end wall portion 1a of the sheet cassette l. When the sheet cassette 1 is installed, the flat plate portion 74c9 of the arm 74b of the bracket 03) 74 is pressed against the tip wall portion 1a of the sheet cassette 1 and rotated clockwise in FIG. 73 to rotate the retard support shaft 71 clockwise. Thereby, the retard roller 61 is biased in a direction in which it comes into pressure contact with the retard drive roller 6 via the pin 72 and the support frame 66.

Next, the operation of the retard device configured as described above will be explained. First, as shown in FIG. 6, when the seat cassette 1 is installed, the bracket (B) 74. Retard spring 75. The retard support shaft 71 is rotated clockwise via the bracket (8) 73, and the retard roller 61 is in pressure contact with the retard drive roller 6 via the pin 72 and the support frame 66.

When the retard drive roller 6 and paper feed roller 5 rotate in the direction of the arrow with the start of sheet feeding, the sheet 4 is sent out from the sheet cassette l, but the sheet 4 is stuck in the pressure nip between the retard roller 61 and the retard drive roller 6. The retard roller 610 is rotationally driven by the rotational driving force of the retard drive roller 6 until it reaches . When the retard roller 61 rotates,
The slack portion 65b of the coil spring 65, whose press-fit portion 65a is press-fitted to the shaft portion 62, is now wound tightly around the shaft portion 62, and the retard roller 61 rotates until it is completely tightened and wound. After the retard drive roller 6 is completely wound, the restoring force of the tightly wound coil spring 65 accumulates an urging force that tends to rotate the retard drive roller 6 in the opposite direction.

In this state, when sheets are fed by the paper feed roller 5 so as to be overlapped at the pressure nip between the retard drive roller 6 and the retard roller 61, the driving force of the retard drive roller 6 no longer acts on the retard roller 61. In this case as well, by setting the accumulated biasing force of the coil spring 65 to be greater than the adhesion force and frictional force of the multi-feed sheets,
The lower sheet in contact with the retard roller 61 is pushed back upstream by the reverse rotation of the retard roller 61 due to the restoring force of the coil spring 65, and double feeding is prevented. Note that after the sheet is fed, the retard roller 61 is driven by the retard drive roller 6 which rotates for a while even after the sheet is fed, and the biasing force is accumulated again, and this state is maintained even when the drive is stopped.

When the sheet cassette 1 is removed from the main body of the apparatus, the pressing force on the flat plate part 74c of the arm 74b of the bracket (8) 74, which was pressed by the contact with the tip wall part 1a of the sheet cassette 1, is released, and the support is thereby released. The shaft 71 rotates counterclockwise, and the retard roller 61, which was in pressure contact with the retard drive roller 6 via the pin 72 and the support frame 66, moves away from the retard drive roller 6, and the nip portion is closed. It will be canceled.

As a result, the coiled spring 65, which had been tightly wound, rapidly rotates the retard roller 61, and is released.

During this rapid rotation of the retard roller 61, the press-fit portion 65a and the shaft portion 62 of the coil spring 65 also rotate slightly relative to each other due to inertia, causing a shift. Therefore, when the sheet cassette 1 is next installed and the retard roller 61 is brought into pressure contact with the retard drive roller 6 again, the surface of the retard roller 61 that was in pressure contact with the retard drive roller 6 is shifted, and the retard roller 61 is brought into pressure contact with the retard drive roller 6 with a new, different surface. I will do it. This makes it possible to extend the life of the retard roller 61.

Further, in this embodiment, the support frame 66 has its notch groove 69
a, 70a is engaged with a pin 72 provided on the support shaft 71,
Since it is swingably supported by the pin 72, when the retard roller 61 is pressed against the retard drive roller 6, the retard roller 61 can be pressed evenly over its entire length. This makes it possible to prevent skewed sheet feeding and uneven wear of the rollers.

〔Effect of the invention〕

As described above based on the embodiments, according to the present invention, the return movement of the retard member due to the stress accumulated when the drive roller and the retard member are driven is stronger than the adhesion force between the multi-feed sheets or *vibration force. Since a pulling force can be applied, double feeding of sheets can be reliably prevented.

Further, by configuring the retard member as a retard roller, and by configuring the retard roller so that the pressure contact portion of the retard roller is displaced when the roller is released from pressure contact with the drive roller, the life of the retard roller can be extended. In addition, by supporting the retard roller so that its axis can swing, it can be brought into uniform pressure contact with the drive roller.
It is possible to prevent skewing of sheets and uneven wear of rollers.

[Brief explanation of the drawing]

Fig. 1 is a plan view showing an embodiment of the retard device according to the present invention attached to the main body of the device, Fig. 2 is an exploded view of the parts of the retard roller portion, and Fig. 3 is an assembled sectional view thereof. , FIG. 4 is a perspective view showing how it is attached to the main body side, FIG. 5 is a plan view partially showing the second embodiment of the present invention in cross section, and FIG.
The figure is a plan view showing a state in which the third embodiment of the present invention is attached to the apparatus main body side and a sheet cassette is attached, FIG. 7 is a partially exploded perspective view of the retard roller section, and FIG. 8 is a FIG. 9 is a cross-sectional view showing a state in which the retard roller is held on a support frame, FIG. 9 is a plan view showing an example of the configuration of a conventional retard device, and FIG. 10 is an exploded perspective view thereof. In the figure, 1 is a sheet cassette, 2 is a sheet 4 placement plate, 5 is a paper feed roller, 6 is a retard drive roller, and 7 is a sheet cassette.
1 is a retard roller, 11 is a roller core, 12 is a rubber roller, 13 is a groove, 14 is a stopper, 17 is a clutch shaft, 1
9 is a clutch tooth, 20 is a stopper portion, 21 is a coil spring, 25 is a support frame, 35 is a circular spring plate, 36 is a locking piece, 37
is a pin, 39 is a support shaft, 51 is a retard pad, 52 is a support plate, 53 is a return spring, 54 is a pressure spring, 61 is a retard roller, 62 is a shaft portion, 65 is a coil spring, 65a is a press-fitting portion, 65b is a slack part, 66 is a support frame, 69a, 70a
71 is a notch groove, 71 is a support shaft, 72 is a pin, 73 is a bracket (c), and 74 is a bracket.

Claims (1)

[Claims] 1. In a retard device of a sheet feeding mechanism that elastically presses a drive roller to prevent double feeding of sheets, a retard member that is driven by the rotation of the drive roller and an elastic member that is driven by the rotation of the drive roller are provided. means for accumulating stress, and is configured to apply a retracting force to the sheet in contact with the sheet by a return operation of a retard member due to the stress accumulated in the stress accumulation means. Mechanism retard device. 2. The retard member is composed of a retard roller, which accumulates elastic stress by rotating together with the drive roller, and applies a retracting force to the sheet by reverse rotation due to the accumulated stress. A retard device for a paper feed mechanism according to claim 1. 3. A means for releasing the pressure contact of the retard roller with the drive roller, the stress accumulation means being constituted by a spring member partially press-fitted to the rotating portion of the retard roller, and the retard roller being driven by the pressure release means. When the stress accumulated in the spring member is released due to separation from the roller, the inertial force of the retard roller causes the press-fitted portion of the spring member to shift, and the portion of the retard roller that is in pressure contact with the driving roller is displaced. 3. A retard device for a paper feed mechanism according to claim 2. 4. The retard device for a paper feeding mechanism according to claim 2 or 3, wherein the retard roller is supported so that its axis can swing and is configured to uniformly press against the drive roller. 5. The retard member is composed of a retard pad, which accumulates elastic stress due to displacement due to frictional force with the drive roller, and applies a pulling force to the sheet by a return action due to the accumulated stress. A retard device for a paper feed mechanism according to claim 1.