JPH01139432A - Overlap feed preventing type paper feeding device for picture image forming device - Google Patents

Abstract

PURPOSE:To make it easy to remove a paper clogging between a carrying means and an overlap feed preventing means by providing a blank form feeding cassette with the overlap feed preventing means to allow the overlap feed preventing means to get out of a cassette charging part together with the blank form feeding cassette. CONSTITUTION:Frictional resistance caused by a friction member 47 is given to an overlap feed preventing roller 20 attachedly provided on a paper feeding cassette 10 at every time when the cassette 10 is drawn out of a cassette charging part 11, and the overlap feed preventing roller 20 is thereby rotated as much as a fixed angle in a direction P opposite to that of paper feeding. Thus a nipping space between a carrying roller 19 and the overlap feed preventing 20 is varied to prevent the nipping surface of the roller 20 from partially wearing. In addition, since the roller 20 can be drawn out of the cassette charging part 11 together with the blank form feeding cassette 10, the paper clogging between the carrying roller 19 and the overlap feed preventing roller 20 can be easily removed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a double-feed prevention sheet feeding device installed in an image forming apparatus such as an electrostatographic copying machine or a printer.

[Conventional technology]

For example, Japanese Patent Application Laid-Open No. 61-273444 was developed as a paper feeding device with a function to prevent double feeding, which is installed in the paper feeding section of an electrostatographic copying machine.
As seen in the above publication, a conveying means and a double feeding prevention means each having a frictional resistance greater than the frictional resistance between the sheets are provided in the paper feeding section, and the double feeding prevention means is linked to the insertion and removal of the paper feeding cassette. A configuration has been proposed in which the paper is rotated by a predetermined angle in the opposite direction.

According to the above configuration, when two sheets of paper are fed between the transport means and the double-feed prevention means, only the paper on the transport means side is fed based on the difference in frictional resistance. This prevents double feeding of paper.

By rotating the double-feed prevention means little by little in the opposite paper feeding direction, the nip surface of the double-feed prevention means with respect to the conveyance means is changed, thereby preventing uneven wear of the double-feed prevention means. Therefore, the function of preventing double paper feeding can be maintained well over a long period of time without requiring a dedicated drive device for rotating the double feeding prevention means.

[Problem that the invention seeks to solve]

By the way, in the double-feed prevention sheet feeding device configured as described above, double-feeding of paper is properly prevented, but it is extremely rare for paper to become jammed between the conveyance means and the double-feed prevention means. Moreover, since the entire double-feed prevention conveyance device is provided in the main body of the apparatus, it is difficult to remove the jammed paper.In addition, the double-feed prevention means and the conveyance means become dirty and the paper is not fed easily. It was also difficult to clean the paper when it became defective and to replace the double-feed prevention means, which wears out faster than the conveyance means.

Moreover, the structure for converting the insertion/removal movement of the paper feed cassette into the rotational movement of the double feeding prevention means is complicated, and when the paper feeding cassette is loaded, an impact is applied to the rotation mechanism of the paper feeding cassette and the double feeding prevention means. Moreover, it is difficult to assemble such a rotating structure in the narrow space of the paper feeding section.

The present invention has been made in view of the above circumstances, and
The object of this invention is to solve all of the above-mentioned conventional drawbacks through extremely simple and rational improvements.

Means for Solving the Problem c] In order to achieve the above object, the present invention comprises a conveying means and a double feeding prevention means that is rotatable only in the counter-feeding direction via a unidirectional drive transmission means. A double-feed prevention paper feeding device for an image forming apparatus, wherein the double-feed prevention means is provided in a paper feed cassette, and when the paper feed cassette is inserted into and removed from a cassette loading section, the double-feed prevention means is moved in the opposite paper feeding direction. It is characterized in that it is equipped with a rotation mechanism that rotates it by a predetermined angle.

[Effect]

According to the above characteristic structure, each time the paper feed cassette is inserted or removed, the double feed prevention means attached to the paper feed cassette is rotated by a predetermined angle in the opposite paper feed direction, and the double feed prevention means nip surface is changed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 schematically shows an electrostatographic copying machine as an example of an image forming apparatus. 2
The photoreceptor 3 is horizontally mounted on the holder, and around the photoreceptor 3,
Charging device 4, developing device 5, transfer device 6, paper separation device 7
, a cleaning device 8 is arranged in this order in the rotational direction of the photoreceptor 3, an exposure device 9 is provided in the upper space of the copying machine main body 2, and a paper feed cassette 10 is loaded in the lower space of the copying machine main body 2. furthermore, a paper feed conveyance device 13 is provided extending from the paper feed device 12 having a function of preventing double feeding to the transfer device 6;
A manual paper feed section 14 is provided in the middle of the path, while a paper discharge conveyance device 16 conveys the paper after transfer and separation to the fixing device I5.
and a paper ejection roller pair 17 that feeds out the paper after fixing, and
A paper discharge tray 18 is provided to receive the fed paper while winding it up.

The double-feed prevention paper feeding device 12 includes an upper conveyance roller 19 made of rubber, for example, which is an example of a conveyance means, on the copying machine main body 2 side, and a lower double-feed roller, which is an example of a double-feed prevention means, made of rubber, for example. A prevention roller 20° 20 is provided in the paper feed cassette 10, and this double feed prevention paper feed device 12
A paper feed roller 21 is disposed on the upstream side in the paper feeding direction.

The frictional resistance of the transport roller 19 is greater than the frictional resistance of the double-feeding prevention roller 20.20, and the frictional resistance of the double-feeding prevention roller 20.20 is set to be greater than the frictional resistance between sheets. Therefore, the paper feed roller 21 transfers two sheets of paper to the transport roller 1 in a stacked state.
When the paper is fed between the transport rollers 9 and the double-feed prevention rollers 20 and 20, the paper is fed by the transport rollers 19 based on the frictional resistance.

The details of the double feed prevention sheet feeding device 12 will be explained as follows.
As shown in FIGS. 1 and 3, a pair of brackets 24.24 are connected to the roller support member 23 extending over the front and rear side plates 22.22 of the copying machine main body 2.
A drive shaft 25 is installed on the drive shaft 25, and the conveyance roller 19 is provided on the drive shaft 25. A pair of arms 26 and 26 are pivotally connected to the drive shaft 25, and are driven via a belt-type interlocking mechanism 27. The interlocking shaft 28 that is
6.26, and the paper feed roller 21 is provided on this interlocking shaft 28.

Note that a solenoid 29 is installed on one side of the arm 26.26.
An L-shaped bell crank 30 connected to the paper feed roller 21 is linked, and when the solenoid 29 is energized by the input of a paper feed signal, the paper feed roller 21 is lowered by its own weight and is housed in the paper feed cassette 10. The uppermost sheet on the mounting plate 31 is fed toward the double-feed prevention sheet feeding device 12.

Further, the roller support member 23 is provided with a paper detection arm 32 that swings downward under its own weight, and a sensor 33 that detects the lowest state of the arm 32. When all the sheets are fed, the tip of the arm 32 falls downward from the opening 34 of the loading plate 31, and based on this state being detected by the sensor 33, the paper on the loading plate 31 is fed. It is now possible to detect the presence or absence of

Furthermore, as shown in FIG. 4, the front and rear side plates 22, 2
2, the extraction direction C of the paper feed cassette 10,
a first bracket 42 provided with a support pin a projecting from the first bracket 42;
and a second bracket 43 having a screw hole bored through it in the vertical direction, and the roller support member 23
A hole C into which the support pin a is inserted, a hole d which corresponds to the screw hole, and a notch e are formed on both sides of the
The first bracket 42 is relatively connected to the roller support member 23.
The roller support member 23 is placed on the second bracket 43 so as to be inserted into the notch e from below, and the roller support member 23 is slid so that the hole C of the roller support member 23 is inserted into the support pin a. The roller support member 23 is fixed to the copying machine main body 2 side by engaging the hole d with the screw hole and hinged the stopper f to the screw hole.

By removing the paper feed cassette 10 from the cassette loading section 11, cleaning and maintenance inspection of the double feed prevention rollers 20 and 20 provided in the paper feed cassette 10 can be easily performed, and the paper feed cassette 10 can be easily cleaned and maintained. The cassette throat 10 is inserted into the cassette loading section 11.
Open the paper feed lid 44 in the state that it has been pulled out, and remove the component parts (transport roller 19, paper feed roller 21, paper presence/absence detection arm 32, sensor 33) that have been assembled to the roller support member 23 to form a unit. By taking it out from the copying machine main body 2, the above-mentioned component parts can be easily maintained and inspected.

On the other hand, as shown in FIGS. 5 and 6, an opening 40 is formed in the inclined guide plate 35 connected to the mounting plate 31 of the paper feed cassette 10 at a position corresponding to the conveyance roller 19. The inclined guide plates 35 on both sides of the opening 40
A pair of brackets 36 with elongated holes g formed on the lower surface side.
36, and an arm 3 is provided on each of the brackets 36, 36.
7.37 is pivoted. The outer rotating body (hereinafter referred to as
At the same time, a support shaft 39 is inserted into the elongated hole g, and the support shaft 39 is connected to the inner rotary body (hereinafter referred to as a driven rotation side member) of the one-way drive transmission means 38. ) 38b and the free end side of the other arm 37, and the double-feed prevention roller 20.
20, and the double feeding prevention roller 20.
20 toward the conveyance roller 19 side (
For example, a coil spring) 41.41 is installed on the bracket 36°36.

The one-way drive transmission means 38 is connected to its driven rotation side member (and in turn, to the driven rotation side member 3 via the support shaft 39).
Double feeding prevention rollers 20, 20 connected to 8b>
The rotation direction is set such that the reciprocating rotation side member 38b freely rotates only in the counter-sheet feeding direction (counterclockwise direction in FIG. 1) P. In other words, the reciprocating rotation When the side member 38a is rotated in the opposite paper feeding direction P, the driven rotation side member 3 is integrated with the reciprocating rotation side member 38a.
The direction in which the driving force is transmitted is set so that the double feeding prevention rollers 8b and 20 and 20 also rotate in the opposite paper feeding direction P.

As shown in FIG. 7, when the paper feed cassette 10 is loaded into the cassette loading section 11,
As the paper moves in the arrow direction A, the double feeding prevention rollers 20, 20 first come into contact with the conveying roller 19, and as the paper feeding cassette 0 moves in the arrow direction A, relatively. The double-feed prevention roller 20.20 moves in a direction away from the conveyance roller 19, that is, in the arrow direction B, against the biasing means 41.41, and as shown in FIG. As the paper feed cassette 10 moves in the direction of the arrow C when the paper feed cassette 10 is pulled out from the cassette loading section 11, the double feeding prevention rollers 2 (1, 20
It moves in the direction of contact with the conveyance roller 19, that is, in the direction of the arrow, by the urging force of .

That is, the insertion/removal movement of the paper feed cassette 10 (arrow direction A,
C), the conveying roller 19 acts against the biasing force of the biasing means 41.degree.C, thereby causing the double feeding prevention roller 20. 20 is configured to be movable in directions B and D toward and away from the conveyance roller 19.

The conveying roller 19 of the double feeding prevention roller 20.20
A motion conversion means 45 is provided to rotate the double-feed prevention roller 20.20 in the counter-feeding direction based on the movement in the direction in which it comes into contact with the double-feed prevention roller 20.2.
0 in the opposite paper feeding direction P by a predetermined angle.

The above-mentioned motion converting means 45, which is not shown in FIG.
A temporary spring member 4 having a surface portion in a direction perpendicular to the surface connecting the
6.46 is connected to the lower surface side of the inclined guide plate 35 in a state corresponding to the circumferential surface of the double feeding prevention roller 20.20, and felt or sponge is attached to the upper surface of the plate spring member 46.46. A friction member 47.47 such as the like is attached, and
The friction member 47.47 is connected to the double feeding prevention roller 20.
20, which prevents double feeding when the paper cassette 10 moves in the direction C when the paper cassette 10 is removed from the cassette loading section 11. 20 in the approach direction, frictional resistance by the friction member 47.47 is applied to the double feed prevention roller 20.20, and the double feed prevention roller 20.20
is rotated in the opposite direction P.

Each time the paper feed cassette 10 is taken out from the cassette loading section 11, the double feeding prevention roller 20° 20 is rotated by a predetermined angle in the opposite paper feeding direction P. The nip surfaces of the double-feed prevention rollers 20, 20 are changed, so that the double-feed prevention roller 20
．． This prevents uneven wear on the nip surface of the paper sheet 20, and also prevents double feeding of paper over a long period of time.
Roller 2 for preventing double feeding when the paper feed cassette 10 is inserted and removed
A rotating mechanism X that rotates the double-feed prevention rollers 20, 20 by a predetermined angle in the opposite paper feeding direction is configured by the configuration of moving towards and away from the conveying roller 19 of 0.20 and the motion converting means 45. It is being done.

Next, another embodiment of the rotation mechanism X for rotating the double-feed prevention roller 20 by a predetermined angle in the opposite paper feeding direction will be described based on the drawings from FIG. 9 onwards.

In addition, the unidirectional drive transmission means 3 used in the following other embodiments
8, the driven rotating side member 38b, which is an inner rotating body, freely rotates only in the counter-feeding direction (counterclockwise direction in the drawing) P with respect to the reciprocating rotating side member 38a, which is an outer rotating body. Set the rotation direction so that

First, the rotation mechanism X of the first alternative embodiment shown in FIGS. 9 and 10 will be described.

This device includes a bearing 48 that is movable along a long hole formed in the bracket 36, a reciprocating rotation side member 38a of the one-way drive transmission means 38, and a reciprocating rotation side member 38a of the one-way drive transmission means 38 attached to the bearing 48. The support shaft 39 to which the double-feed prevention roller 20 is fixed is attached to the driven rotation side member 38b of the transmission means 38, and the biasing means 49 for biasing the double-feed prevention roller 20 toward the conveying roller 19 side is attached as described above. A motion converting means 45 is provided to act on the bearing 48, and is in contact with the double-feed prevention roller 20 in order to apply frictional resistance to the double-feed prevention roller 20.

In the configuration of this first alternative embodiment, the configuration of the embodiment described based on FIGS. 7 and 8 causes the double feeding prevention roller 20 to swing around the swing axis P2. Therefore, while the double-feed prevention roller 20 is configured to be able to move toward and away from the conveyance roller 19, the double-feed prevention roller 20 can be moved linearly along the elongated hole. The double feeding prevention roller 20 is characterized in that it can freely approach and separate from the conveyance roller 19, and most importantly, the double feeding prevention roller 20 can be moved toward and away from the conveyance roller 19. The manner in which the roller 20 rotates in the opposite paper feeding direction P is approximately the same as in the configuration of the embodiment shown in FIGS. 7 and 8, so a description thereof will be omitted.

Next, the rotation mechanism X of the second alternative embodiment shown in FIGS. 11 to 13 will be described.

In this case, a bracket 53 is provided on the paper feed cassette 10, and a roller holding bracket 55 is pivotally attached to the bracket 53 via a pivot shaft 54.
4 is provided with a large-diameter gear G1, and the gear G is fixed to the bracket 53 by a screw i, while a small-diameter gear G2 that meshes with the gear GI is connected to the reciprocating rotation side member of the one-way drive transmission means 38. 38a, and a spindle 39 is attached to the other driven rotation side member 38b, and this spindle 39 is rotatably provided to the roller holding bracket 55, and the small diameter gear is attached to the spindle 39. Double feeding prevention rollers 20.20 are fixed to both sides of G2, and the double feeding prevention rollers 20.20 are attached to the conveyance roller 19.
A biasing means 56 for biasing the paper feed cassette/notebook 10 is provided across the roller holding bracket 55 and the paper feed cassette/notebook 10.

As shown in FIG. 12, the double feeding prevention roller 2
When the paper feed cassette 10 is further moved in the direction of the arrow A with the paper feed cassette 10 in contact with the conveying roller 19, the urging means 56
The double-feed prevention roller 20 and the roller holding bracket 55 are swung around the pivot shaft 54 in a direction away from the conveying roller 19, that is, in the arrow direction B, and the roller holding bracket 55 is As the small-diameter gear G2 engages with the large-diameter gear G1, it rotates in the clockwise direction due to the rocking, but due to the action of the -direction drive transmission means 38, the rotational force of the small-diameter gear G2 is transferred to the support shaft 39. It is never transmitted.

On the other hand, as shown in FIG. 13, the paper feed cassette 10 is
When is moved in the direction of the arrow C, the double-feed prevention roller 20 and the roller holding bracket 55 are swung in the direction of the arrow, that is, in the direction of the arrow, by the urging force of the urging means 56, and As the roller holding bracket 55 swings, the small diameter gear G2 rotates in the counterclockwise direction P, and the rotational force is transmitted to the double feeding prevention roller 20 through the support shaft 39.

That is, each time the paper feed cassette 10 is taken out from the cassette loading section, the double feed prevention roller 20 is rotated by a predetermined angle in the opposite paper feed direction P, so that the double feed prevention roller 20 is rotated by a predetermined angle in the opposite paper feed direction P. The surface of the knob is changed,
A motion converting means 45 is constituted by the large-diameter gear G+ and the small-diameter gear G2 that meshes with the large-diameter gear G+.

In such a configuration, the smaller the diameter of the gear G2 and the greater the number of teeth, the smaller the rotation angle of the small diameter gear G2 (and the more the double feeding prevention roller 20 With this configuration, each time a single sheet of paper passes between the conveyance roller 19 and the double-feed prevention roller 20, In addition, the double-feed prevention roller 20 moves by the thickness of the paper, and in response to the movement, the double-feed prevention roller 20 rotates very slightly in the counterclockwise direction. This is preferable in that the wear of the double feeding prevention roller 20 is made as uniform as possible.

In addition, the large diameter fixed side gear G1 and the one-way drive transmission means 3
Although the motion converting means 45 is constituted by a small diameter gear G2 provided on the support shaft 39 via a gear G, this may be used as a partial gear instead of the large diameter gear G. The motion converting means 45 may be configured by replacing the partial gears or the large diameter gear G with rollers and applying frictional resistance to the rollers.

Next, a third alternative embodiment of the rotation mechanism X shown in FIGS. 14 and 15 will be described.

This is a spindle 3 with a double-feed prevention roller 20 attached.
9 is pivotally connected to the placket 36 so as to be rotatable only, and
The driven rotation side member 38b of the one-way drive transmission means 38 is attached to the support shaft 39, and the rotated operation member 50 is connected to the other reciprocating rotation side member 38a. A biasing means 51 is attached between the rotated operation member 50 and the bracket 36, and as the paper feed cassette 10 is inserted into the cassette loading section, the Move the operating member 50 in the opposite paper feeding direction P.
The copying machine main body 2 is provided with a member 52 that is rotated.

When the paper feed cassette 10 is pulled out from the cassette loading section, only the rotated operating member 5o moves in the paper feed direction as the paper feed cassette moves in the direction of the arrow C on day 0. Rotate (state shown in Fig. 15).

Then, when the paper feed cassette 10 is moved in the arrow direction A when loading the paper feed cassette 10 into the cassette loading section, the rotated operation member 5o comes into contact with the rotation member 52 and moves counterclockwise. Accordingly, the double feeding prevention roller 20 is rotated by a predetermined angle in the opposite paper feeding direction P.

In each of the above embodiments, the same components as those shown in FIGS. 7 and 8 are given the same reference numerals, and their explanations will be omitted.

In addition, although a roller structure is shown as a means for preventing paper double feeding, a heald structure can be used instead, and it can be used not only in copying machines but also in various image forming apparatuses such as printers and facsimile machines. The paper feeding device in can be targeted for implementation.

Furthermore, although the one-way drive transmission means 38 has been shown to have a structure in which the ball is engaged with and disengaged from a portion of the taper, it goes without saying that a well-known structure such as a structure comprising a ratchet and a ratchet pawl may be employed.

〔Effect of the invention〕

As explained above, according to the present invention, the double feed prevention means is provided in the paper feed cassette so that the double feed prevention means can be removed from the cassette loading section together with the paper feed cassette. By removing the paper from the cassette loading section, you can easily remove paper jammed between the conveyance means and the double-feed prevention means, and also clean, replace, and perform maintenance and inspection of the double-feed prevention means in a large area outside the device. This can be done extremely easily in a small space, and when the paper feeding cassette is removed from the cassette loading section, there is no double feeding prevention means in the paper feeding device section that prevents double feeding.
By using the loading port of the paper feed cassette, maintenance and inspection of the remaining conveyance rollers and paper feed rollers can be easily performed.

Each time the paper feed cassette equipped with the double-feed prevention means is inserted or removed, the double-feed prevention means is rotated by a predetermined angle in the anti-sheet feeding direction using the insertion/removal movement, The structure for preventing double feeding of paper over a long period of time by suppressing uneven wear of the double feeding prevention means can be made simple and inexpensive.

Furthermore, since the double feeding prevention means and the component for rotating the double feeding prevention means in the opposite paper feeding direction are provided on the paper feed cassette side, their assembly is easy and the workability of assembly is improved. Overall, it has been possible to solve all the drawbacks of the conventional technology at once through simple and rational improvements.

[Brief explanation of the drawing]

FIG. 1 is a side view of a paper feeding device to prevent double feeding, FIG. 2 is a schematic vertical side view of an electrostatographic copying machine showing an example of an image forming apparatus, and FIG. 3 is a developed view of the paper feeding device to prevent double feeding. Fig. 4 is an explanatory diagram of the installation of the roller support member, Fig. 5 is a perspective view of the rotating mechanism, Fig. 6 is a detailed view of the one-way drive transmission means, and Figs. 7 and 8 are for preventing double feeding. It is an explanatory diagram of rotation of a mouth-ra. 9 and 9 show other embodiments of the rotating mechanism, FIGS. 9 and 10 are explanatory diagrams of the rotation of the double-feed prevention roller in the rotating mechanism of the first alternative embodiment, and FIG. A perspective view of the rotation mechanism of another embodiment, FIGS. 12 and 13 are explanatory diagrams of the rotation of the double feeding prevention roller in the rotation mechanism of the second embodiment, and FIGS. 14 and 15 are the third FIG. 7 is an explanatory diagram of the rotation of the double-feed prevention roller in the rotation mechanism of another embodiment. 10...Paper feed cassette, 11...Cassette loading section,
19... Conveying means (conveying roller), 20... Double feeding prevention means (double feeding prevention roller), 38... One-way drive transmission means, 38a... Reciprocating rotation side member, 41.49 .5
1.56...Biasing means, 45...Motion converting means, 5
0... Rotatable operation member, 52... Rotating member, P...
・Counter-feeding direction, X...Rotation mechanism. Applicant: Mita Kogyo Co., Ltd. Agent: Hideo Fujimoto, Figure 1, Figure 5, Figure 20...Double feed prevention means (double feed prevention roller) 38...
・One-way drive transmission means 41...Biasing means 45...Motion converting means
- One-way drive transmission means 38a... Reciprocating rotation side member P... Counter-feeding direction 19... Conveyance means (conveyance roller) 20... Double-feed prevention means (double-feed prevention roller) 38.・
・One-way drive transmission means 41...Biasing means 45...Motion converting means P...Counter paper feeding direction X...Rotating mechanism FIG. , × 19... Conveying means (conveying roller) 20... Double feeding prevention means (double feeding prevention roller) 38...
- One-way drive transmission means 38a...Reciprocating rotation side member 45...Motion converting means 19...Transporting means (conveying roller) 20...Double feeding prevention means (double feeding prevention roller) 38...
One-way drive transmission means 38a...Reciprocating rotation side member 45...Motion converting means 50...Turnable operation member 51...Biasing means FIG. 14 52...Rotation member P... Counter-feeding direction X...Rotating mechanism Fig. 15

Claims (3)

[Claims] (1) A double-feed prevention paper feeding device for an image forming apparatus comprising a conveying means and a double-feed prevention means that can rotate only in the counter-feeding direction via a unidirectional drive transmission means, the double-feed prevention means is provided in the paper feed cassette, and a rotation mechanism is provided for rotating the double feed prevention means by a predetermined angle in the opposite paper feeding direction as the paper feed cassette is inserted into and removed from the cassette loading section. Double feed prevention paper feeding device for image forming devices. (2) To configure the rotation mechanism, the double-feed prevention means is provided in the paper feed cassette so as to be able to move toward and away from the conveyance means, and the double-feed prevention means is urged into contact with the conveyance means side. means is provided so that the double feeding prevention means can be moved toward and away from the conveying means as a reaction force member as the paper feed cassette is inserted and removed;
and means for converting the movement of the double-feed prevention means in the direction in which it comes into contact with the conveyance means into the rotational movement of the double-feed prevention means in the counter-feeding direction.
A double feed prevention sheet feeding device for an image forming apparatus described in item 1). (3) In configuring the rotation mechanism, a rotationally operated member is connected to the reciprocating rotation side member of the one-way drive transmission means, and the rotationally operated member is rotated in the paper feeding direction. the paper feed cassette is provided with a biasing means for causing the paper feed cassette to rotate, and a member is provided on the apparatus main body side that rotates the rotated operation member in a direction opposite to the paper feed direction as the paper feed cassette is inserted into the cassette loading section. A double-feed prevention sheet feeding device for an image forming apparatus as set forth in claim (1).