JPH03182433A - Paper feeding device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Al Industrial Field of Application) The present invention relates to a paper feeding device that conveys paper placed on a hopper table to a paper feeding roller on the main body side of an image forming apparatus by means of a preliminary paper feeding roller.

(b) Conventional technology In a paper cassette provided in an image forming apparatus, paper placed on a hopper table is pre-fed by a preliminary paper feed roller to a paper feed roller on the main body side of the image forming apparatus, and then the paper is formed into an image. Some image forming apparatuses feed paper to an image forming process section of the image forming apparatus main body using a paper feed roller of the apparatus main body.

(C) Problems to be Solved by the Invention In the above-mentioned apparatus, a separating claw is provided at the top of the tip of the hopper stand. When the preliminary paper feed roller starts rotating, the separation claw presses the leading edge of the uppermost paper against the force of feeding the paper, forming a loop at the leading edge of the paper. This separates the top paper from the bottom paper and prevents double feeding.

However, in such a device, the leading edge of the next sheet to be fed may curl, causing a jam or a transfer failure. That is, when the length of the paper to be fed is short, the preliminary paper feed roller starts feeding the next paper at the time the first paper reaches the paper feed roller. At this time, if the leading edge of the next sheet forms a loop, the rotation of the preliminary paper feeding roller will stop and the leading edge of the next sheet will be left as it is, resulting in a looping tendency at the leading edge of the sheet.

In view of these problems, an object of the present invention is to provide a paper feeding device that prevents the preliminary paper feeding roller from stopping when the leading edge of the paper is looped, thereby preventing the occurrence of jams and transfer defects. do.

fd1 Means for Solving the Problems This invention provides a feeder that transports paper placed on a hopper stand to a paper feed roller of an image forming apparatus main body by rotation of a preliminary paper feed roller provided at the tip of the hopper stand. In the paper device, means for detecting the paper length in the conveying direction of the paper placed on the hopper stand; and comparison means for comparing the length from the tip of the hopper stand to the paper feed roller with the paper length; The present invention is characterized in that, when the paper length is determined to be shorter by the comparing means, means is provided for continuing the rotation of the preliminary paper feed roller for a predetermined period of time after the paper reaches the paper feed roller.

(e1 Effect In this invention, the paper length is short, and the feeding of the next paper is started before the previous paper reaches the paper feed roller of the main body of the image forming apparatus, and when the previous paper reaches the paper feed roller, Even if the leading edge of the next sheet forms a loop, the rotation of the preliminary paper feed roller does not stop at that point and continues to rotate for a certain period of time.As a result, the next sheet of paper is further fed out and the leading edge of the paper is The loop state is released and the loop habit is no longer formed.

(f) Embodiment ■ Overall configuration FIG. 16 is a schematic front view of a copying machine equipped with a large-capacity cassette, and FIG. 15 is an external view.

In the figure, 1 is a cassette body that is inserted into the copying machine body, 2 is a cover made of transparent resin such as acrylic, 3 is a side bottom plate fixedly arranged inside the cassette body, and 4 is a hopper stand on which paper is placed. It moves up and down along belts 5 provided on both side surfaces. Sensors (microswitches) Sl and S2 are provided at the limit positions of the vertical movement of the hopper stand 4, and when the sensor S1 detects paper or the hopper stand, the rising of the hopper stand 4 is stopped, and the sensor S2 detects the hopper stand 4. When this is detected, the lowering of the hopper stand 4 is stopped. A door switch S3 is provided on the cassette body 1 at a position opposite to the cover 2.
Detects the open/closed status of the When the cover 2 is closed, the hopper stand 4 rises, and when the cover 2 is opened, the hopper stand 4 descends to the lower limit position.A guide plate 6 is provided in front of the side bottom plate 3, and a guide plate 6 is provided in front of the side bottom plate 3. Guide the paper. Reference numeral 8 denotes a preliminary paper feed roller that contacts the paper on the hopper table 4 and feeds the paper. Further, reference numeral 9 denotes an auxiliary roller provided between the preliminary paper feed roller 8 and the paper feed roller 7. A separation claw 10 is provided at the tip of the hopper table 4. The preliminary paper feeding roller 8 is provided near the separating claw 10. Here, the distance between the separation claw 10 and the paper feed roller 7 (paper detection sensor 34) is Ll, and the length of the minimum size paper is L2. Auxiliary roller 9 is Ll>L
2, this is provided to prevent paper conveyance from stopping midway along the guide plate. For example, in this device, L2 is B
The auxiliary roller 9 is a spare roller provided in the center where the distance between the rollers 8-9 and the distance between the rollers 9-7 are each 100n. Paper feed roller 8. The paper is sent to the paper feed roller 7 by the auxiliary roller 9, and is detected by the sensor S4. Then, by rotating the paper feed roller 7, the paper is sent to a position between the photoreceptor 50 and the transfer device 51 of the main body of the copying machine.

Note that reference numerals 11 and 12 are regulating plates, which are movable inward (in the direction of arrow A) and outward (in the direction of arrow B), respectively.

Each mechanical section will be explained in detail below. FIG. 3, FIG. 13, and FIG. 14 are perspective views showing the configuration of main parts of the large-capacity cassette.

(2) Hopper table moving mechanism In FIG. 14, the side bottom plate 3 is fixed to the cassette body as described above. On the other hand, the rollers 4a provided on both side surfaces of the hopper table 4 are attached to a belt (5) (not shown).
Move up and down by moving along. Hopper stand 4
The parts stored in the cassette body 1 include three plates 4b,
4b and 4c, and the cover 2 is composed of a mounting table 4d. The center mounting table 4c has a width that almost matches the width of the smallest size paper, and is fixed to the outer mounting table 4d. Slide hopper stands 4b, 4b are mounting stands 4
c is movable in the directions of arrows A and B, and is moved in accordance with the size of the paper placed on the hopper table. This movement is performed by a regulating plate. That is, the regulating plates 11.12 shown in FIG. 13 are loosely fitted into the retaining parts 4e, 4e on the sides of the slide hopper stands 4b, 4b, and when the regulating plates 11.12 move in the directions of arrows A and B, The slide hopper stands 4b, 4b move in the directions of arrows A and B. Note that the slide hopper tables 4b, 4b move in the vertical direction along the regulating plate 1112, but the regulating plate 11.1 in the retaining portion 4e
There is some play in the attachment of 2, and the hopper table can be easily moved up and down.

(2) Regulating Plate Moving Mechanism In FIG. 13, the regulating plates 11 and 12 move in the directions of arrows A and B along reinforcing plates 13 fixed to the cassette body at both ends. Each of the regulating plates 11 and 12 is provided with horizontal pieces 11a and 12a at the upper part thereof, and is supported by the reinforcing plate 13 here.

Slits 14a and 15a are formed in the bottom surface of the reinforcing plate 13 along the moving direction of the regulating plate 11.12. Slide shaft 16a along these slits 14a, 15a
is passed, and the regulating plate mounting portion 14 is attached to the slide shaft 16a.
b, 15b is inserted. Regulation plate mounting part 14b, 1
5b each has a regulating plate fixing part fixed to the regulating plate 11, 12, a slide spring, and a wire attachment part.

The regulating plate fixing portion of the regulating plate mounting portion 14b is screwed onto the regulating plate 11 through the slit 14a.

Further, the regulating plate fixing portion of the regulating plate mounting portion 15b has a slit 15.
It is screwed onto the regulating plate 12 through the hole a. Then, the wire 16 is attached to the wire attachment part above the slits 14a and 15a.
d is stretched.

Pulleys 16b and 16c are attached to the side piece of the reinforcing plate 13 along the slide shaft 16a.
A wire 16d is stretched between the wire mounting portions b and 16C and the wire mounting portions of the regulating plate mounting portions 14b and 15b. FIG. 4 is a diagram showing this state. One end of the wire 16d is fixed to the reinforcing plate 13, and the regulating plate attachment part 14b and the pulley 16
It is fixed to the other regulating plate mounting portion 15b via b. Further, the wire 16d is fixed to the regulating plate attachment portion 14b via a pulley 16c.

With such a configuration, for example, when the regulation plate attachment part 14b moves in the direction of arrow A, the other regulation plate attachment part 15b is pulled and moves in the direction of arrow A by the same distance as the regulation plate attachment plate 14b. Conversely, if the regulation plate attachment part 14b moves in the direction of arrow B, the regulation plate attachment part 15b also moves by the same distance in the direction of arrow B. Note that the same operation also occurs when the regulating plate attachment portion 15b is moved. At this time, the regulation plate mounting portion 14
a15a moves smoothly along the slide shaft 16a.

The regulation plate attachment part 14a is attached to the horizontal piece 11a of the regulation plate 11, and the regulation plate attachment part 15a is attached to the horizontal piece 1 of the regulation plate 12.
2a. On the horizontal pieces 11a and 12a, a regulating plate mounting portion 14a is provided.

15a is fixed at a position slightly forward of the center of gravity P of each regulating plate. When the regulating plate 11.12 is in a free state (when the lock described later is released), the regulating plate 11.12 is suspended by the regulating plate mounting portions 14a and 15a, with the lower end facing toward you (hereinafter referred to as Fig. 16). The right side is called the front and the left side is called the back). In this state, if you hold the levers Ilb and 12b provided on each of the regulating plates 11.12 and move the regulating plate 11.12 in the direction of arrow A or B, the regulating plate will slide.
a, and the regulating plates 11, 12 can be easily moved to a position corresponding to the width of the paper. Note that 16e is a size label indicating the position of the paper width of the specified size. The regulating plates 11.12 are locked by a locking mechanism to be described later.
12 is held vertically by locking its lower end.

Rollers 17a and 18a for facilitating the movement of the aforementioned regulating plates 11 and 12 are attached to the back of the center of gravity (2).

Slits 17b and 18b are formed on the bottom of the reinforcing plate 13 at the rear of the slits 14a1 and 5a.
The roller 17a is screwed to the horizontal piece 11a through b,
A roller 18a is screwed onto the horizontal piece 12a through the slit 18b. FIG. 5 is a perspective view showing how the roller 17a (18a is also attached in the same way) is installed, FIG. 6 is a front view thereof, and FIG. 7 is a side view. The support shaft 17d of the roller 17a is attached to the regulating plate 11 by a roller attachment portion 17C. The roller mounting portion 17c is a box-shaped portion into which the support shaft 17d is loosely fitted, with legs formed therein, and rotatably supports the roller 17a in a lifted state from the regulating plate 11. Note that this support part does not use bearings or the like, so there is no increase in cost.

When the regulating plate 11 is locked, the rollers 17a are lifted off the reinforcing plate 13 as shown in FIG. 7(A), and the rollers 17a do not come into contact with the reinforcing plate 13. However, when the regulation plate 11 is unlocked, the regulation plate 11 is tilted and the rear side is lowered from the regulation plate mounting portion 14b, so that the rollers 17a come into contact with the reinforcing plate 13 (FIG. 7(B)). If the regulating plate is moved in the direction of arrow A or B in this state, the rollers 17a will rotate accordingly, making it easier to move the regulating plate 11. Further, as shown in FIG. 6, the mounting plate 17c is formed so that its upper surface is inclined from the front toward the rear. When the regulation plate 11 is unlocked, the mounting plate 17
This is to ensure that the upper surface of roller c is parallel to the support axis 17d of the roller. With this configuration, the roller 17a
When the mounting plate 17c rotates along the reinforcing plate 13, it is possible to prevent uneven rotation caused by the edge portion of the mounting plate 17c rubbing against the support shaft 17d.

A positioning bin 1 is located further back from the horizontal pieces 11a and 12a.
1c and 12c are provided. This positioning bin Il
Concave portions (not shown) are formed at positions corresponding to the widths of the various sheets of paper on the reinforcing plate 13, facing the paper sheets 12c and 12c. As a result, the regulating plates 11, 12 are positioned at positions corresponding to various paper widths. Furthermore, a roller positioning member 1id for positioning the preliminary paper feeding roller 8 is provided at the rear end of the horizontal pieces 11a and 12a.
12d is attached (described later).

■ Regulation plate lock mechanism The regulating plate 11.12 has a groove 11e in the vertical direction.

12e is formed. The roller 4a of the hopper stand 4 moves along the grooves 11e and 12e, and the hopper stand 4 is moved in the vertical direction. A locking portion 1 is provided at the lower end of the regulation plate 11.
1f, ilg, and a locking portion 12f at the lower end of the regulating plate 12.
, 12g are provided respectively. Front locking part 11g,
12g, as indicated by arrows F, are engaged and locked by locking portions 19 and 20 provided on the side bottom plate in FIG. 14. Further, the rear locking portion 11f is locked to the size detection portion 23 provided on the side bottom plate 3 as shown by arrow C, and the locking portion 12f is locked to the regulation plate detection portion 24.

FIG. 8 is a sectional view of the lock portion 19. A substantially U-shaped lock angle 19a with an open bottom is screwed onto the side bottom plate 3. A notch 19b is formed from the top surface of the lock angle 19a to the front side surface. The notch portion 19b is tapered gradually at the back side of the upper surface, and the retaining portion 11g of the regulating plate is held therebetween. This notch 19b
A plurality of sheets are formed to match the widths of various types of paper. When placing paper on the hopper stand 4, the regulation plate 11 is moved to a predetermined position according to the width of the paper placed on the hopper stand 4,
It is pushed into the opposing notch 19b from the front toward the back. Inside the lock angle 19a is a plate spring 19.
C is provided, and when the regulating plate 11 is pushed into the notch 19b, the retaining portion 11g overcomes the leaf spring 19c, and is urged toward the rear by the leaf spring 19C. In this way, the regulation plate 11 is locked at a position corresponding to the width of the paper. The regulating plate 12 is similarly locked by the lock portion 20.

The regulation plate 11 is unlocked as follows.

A lock release member 2Ib is provided on the side of the lock angle 19a.
A lock release angle 21a is provided to support the lock release angle 21a. FIG. 9 is an external view of the lock release member 21b. The lock release member 21b has a lock release portion 21c parallel to the leaf spring 19c and a pressing piece 21d having a flat surface in the front direction. The lock release member 21b is rotatably supported by the lock release angle 21a at a support portion 21e.

When the pressing piece 21d is pressed, the lock release member 21b rotates, and the lock release portion 21c is rotated as shown in FIG. 8(B).
presses and lifts the leaf spring 19c. Then, the locking part 1
1g is released, the lower end of the regulating plate 11 is pushed forward as shown by the arrow in the figure, and the lock is released.

Pressing of the pressing piece 21d is performed by a lock release lever 22a provided on the hopper stand 4. Lock release lever 2
2a is attached to a lock shaft 22b, and the lock shaft 22b is rotatably supported. Lock pressers 22c are provided at both ends of the lock shaft 22b. When the lock release lever 22a is pressed, the lock shaft 22b rotates in the direction of the arrow in the figure, and the lock presser 2
2C presses the pressing piece 21d of the unlocking member.As described above, the regulating plate 11.12 can be locked simply by pushing it toward the rear side, and the lock can be released by pushing the lock release lever 22a. I can do it. In addition, when the hopper stand 4 is not lowered, even if the lock release lever 22a is pushed, the lock presser 22c is moved to the pressing piece 21d.
Since there is no contact with the regulating plates 11 and 12, there is no possibility that the regulating plates 11 and 12 will be unlocked.
．． 12 can be prevented from being unlocked. Further, since the lock release lever 22a is provided in the center of the hopper table 4, that is, in a position where it is hidden even when the smallest size paper is placed, it is possible to prevent the occurrence of erroneous operation.

■Regulation Plate Detection Device The rear locking portion 11f of the upper restriction plate 1 is inserted into the size detection portion 23 as described above. A plurality of notches 23b are formed in the size detection angle 23a of the size detection section 23 in accordance with the paper width. This notch 23b
are formed from the top surface to the front side surface, similar to those provided in the lock angles 19 and 20 described above, and the regulating plate 11 is held at the rear part of the top surface. A size detection board 23c is provided inside the size detection angle 23a. The size detection board 23C is provided with a plate spring 23d (see FIG. 10) according to the paper width, that is, the notch 23b, and when the regulating plate 11 is inserted into the notch 23b, the plate spring 23d is pressed downward. The tact switch 23e corresponding to the width of each sheet of paper arranged in the paper is turned on.

The rear locking portion 12f of the regulation plate 12 is inserted into the regulation plate detection unit 24. The regulation plate detection section 24 is also provided with a regulation plate detection angle 24a, and the locking part 12f is inserted into a notch 24b provided according to the paper size. A leaf spring (not shown) is arranged within the regulation plate detection angle 24a. This leaf spring turns on a switch 5w1 (not shown) to detect the locked state of the regulation plate 12.

(2) Separation claws 10 are provided at the upper front ends of the paper feed mechanism regulating plates 11 and 12, respectively. The hopper table 4 on which the paper is placed is connected to the sensor S1
until the top paper is detected. At this time, the uppermost paper comes into contact with the separation claw 10.

When the sensor S1 is turned on, the preliminary paper feed rollers 8, 8 come into contact with the upper surface of the uppermost paper. The preliminary paper feeding rollers 8, 8 and the auxiliary roller 9 are rotationally driven by a motor 25. The motor 25 is held by a motor frame 25a, fixed to the reinforcing plate 13 as shown by arrow G, and transmits driving force to the preliminary paper feeding rollers 8, 8 and the auxiliary roller 9. The driving force of the motor 25 is first transmitted to the paper feed drive shaft 26 by a belt. From here, the belt 8b transmits the driving force to the shirt 1-8a that supports the preliminary paper feed rollers 8, 8, and the belts 9b, 9C transmit the driving force to the shirt t-9a that supports the auxiliary roller 9. 8a is supported so as to be slightly movable in the vertical direction. This is because the preliminary paper feed roller 8.8 rides on the topmost paper by its own weight. The pre-feed roller 8.8 is connected to the shaft 8 via a one-way clutch.
It is supported by A and is movable in the directions of arrows A and B.

The roller positioning members 11d and 12d are the preliminary paper feeding rollers 8.
．． 8, and are attached to regulating plates 11 and 12, respectively. Therefore, when the regulating plates 11, 12 move in the directions of arrows A and B, the preliminary paper feed rollers 8 and 8 also move in the directions of arrows A and B accordingly. Furthermore, as shown in FIG. 11, the regulation plate 1
The shaft 8a is located approximately 20 mm from the front end of the regulating plate 11.12, and the preliminary paper feed roller 8a is located approximately 30 mm from the side surface of the regulating plate 11.12.
will be moved. By setting the preliminary paper feeding rollers 8, 8 at such positions, it is possible to reliably feed paper regardless of the width of the paper.

As shown in FIG. 12, a plate spring 27a is provided on the guide plate 6 below the auxiliary roller 9 and is spot-welded to the guide plate 6 to press the auxiliary roller 9 upward. This pressing force is preferably about 150 g. The upper surface of the leaf spring 27a is covered with a film 27 made of foamed urethane, artificial leather, etc. with a high coefficient of friction.
b is attached to prevent double feeding of paper. Generally, paper used in copying machines is packaged in wrapping paper coated with a paraffin moisture-proofing agent. Therefore, the moisture-proofing agent adheres to the outermost paper, reducing frictional resistance and causing double feeding.In the case of large-capacity cassettes, multiple bundles of paper are stored in the cassette at once and used in sequence. Therefore, double feeding is likely to occur at each boundary of the paper bundle. Therefore, double feeding is prevented by the film 27a. Note that the paper feeding force by the auxiliary roller 9 is approximately 300 to 6
If a film with a very high coefficient of friction is used, poor paper conveyance may occur, so the film should be selected appropriately. Note that 27c is leaf spring 2
This is a resin film attached to eliminate the level difference caused by 7a.

■ Control section FIG. 2 is a block diagram of the control section of the large capacity cassette.

The operation of the large capacity cassette is controlled by a controller 30. The controller 30 has upper and lower limit sensors Sl, S2,
Inputs are received from the door switch S3, paper detection sensor S4, size detection board 23c, and the like. Size detection board 23c
is connected in parallel with the lock confirmation switch SWI of the regulation plate 12 provided in the regulation plate detection unit 24, and both regulation plates 1
Size sensing data is input to controller 30 only when 1.12 are securely locked together.

Based on these detections, the motor 31 for moving the hopper stand 4 and the paper feed motor 25 are driven.

(2) Operational Description FIG. 1 is a flowchart showing the operating procedure of the large capacity cassette.

The door switch S3 is turned on when the door 2 is opened.

When the door switch S3 is turned on, the hopper stand motor 31 rotates in the opposite direction to lower the hopper stand 4 (nl→n2) to enable paper replenishment. When the hopper stand 4 descends to the lower limit position, the sensor S2 is turned on (n3). Then, after t1 time has elapsed, the hopper stand motor 31 is turned off and the descent of the hopper stand 4 is stopped (n4→n5).
The time is only a short time of about 1 second, and the hopper stand 4 will not fall too much and the cassette body 1 will not be damaged. By stopping the hopper stand 4 t3 hours after the sensor S2 is turned on, the lock presser 2 of the lock release lever is
2c comes into reliable contact with the pressing piece 21d, and the problem of inability to release the lock can be prevented from occurring.

When the hopper stand 4 is completely lowered, the lock release lever 2
When 2a is pressed, the locking of the regulating plates 11 and 12 is released, and the lower part of the regulating plate is pushed forward. In this state, if one or both of the levers 11b and 12b is slid to match the size position of the paper on which the size label 16e is placed, both the regulation plates 11 and 12 will move by the same distance, and the locking part of the regulation plate will move. 11g, llf, 12g, and 12f face the notches 19b, 23b, 20b, and 24b, respectively.

If the lower end of the regulating plate 11.12 is pushed to the rear, the locking portion is locked, and the regulating plate will not be displaced even if vibrations are applied due to paper feeding. Re-regulating plate 11.
12 is securely locked, the switch Swl
is turned on, one of the tact switches 23e is turned on, and the paper size is input to the controller. When the user places paper on the hopper table 4 and closes the cover 2, the door switch S3 detects this.

When the sensor S3 is turned off (nil), the motor for moving the hopper stand rotates in the forward direction, and the hopper stand 4 rises to the position of the sensor S1 (n12→n13→n14). This brings the preliminary paper feed rollers 8, 8 into contact with the uppermost paper. This completes the setting of paper into the cassette main body.

When a large-capacity cassette selection signal is input from the control section of the copying machine main body (n21L and n22 determine whether or not the paper size is detected.The re-regulating plates 11 and 12 are locked to determine the paper size. If the size is detected, at least one of the regulating plates 11 and 12 is in a lock failure state.If the paper size is not detected, for example, there may be a lock failure when setting the paper or some other cause. n2 if the lock comes off with
In step 3, a message to the effect that paper feeding is prohibited is sent to the copying machine main body as an error process. This makes it possible to prevent the regulation plates 11 and 12 from shifting during paper feeding due to forgetting to lock the paper, thereby preventing the paper from being skewed and jammed.

If the paper size has been detected, reception of a paper feed start signal is waited for (n24). When the copying process is started in the copying machine main body, a paper feed signal is sent to the large capacity cassette. Then, the controller 30 compares I, i and Ll.
(see figure), if Ll<Ll, proceed to n26 and L1≧L
In case of 2, proceed to n29. L when paper feeding process is performed
If l<Ll, even when the leading edge of the paper reaches the paper feeding roller 7, the trailing edge remains in contact with the preliminary paper feeding roller 8.

However, when Ll≧L2, the trailing edge of the paper leaves the preliminary paper feed roller 8 before the leading edge of the paper reaches the paper feed roller luff, and the next paper starts to be fed by the preliminary paper feed roller 8, and then the first paper starts to be fed out by the preliminary paper feed roller 8. The paper reaches the paper feed roller 7. At this time, the leading edge of the next sheet may be looped by the separation claw 10, and if left as is, the leading edge of the sheet may form a loop, causing jams and transfer failures during image formation processing. Become.

Therefore, in the case of L1≧L2, the difference ΔL between Ll and Ll is calculated, and if this is smaller than the predetermined length, it is assumed that the next sheet will be left in a looped state, and in order to eliminate this, n31 ~Proceed to the process of n34 (n25→n29
→n30). First, the paper feed motor 25 is turned on to start preliminary paper feeding (n31). When the leading edge of the paper reaches 34, the paper feeding roller is then rotated for t2 hours to continue feeding the paper until the leading edge of the paper definitely leaves the separating claw 10 (n32→n33). Then, when the leading edge of the paper leaves the separating claw 10, the paper feed motor n34 is turned off.

On the other hand, if Ll<Ll, the paper feed motor 25 is turned on until the paper feed sensor S4 detects the paper to feed the paper (n26→n27→n28).

Note that in the case of ΔL, the second sheet of paper has already passed through the separation claw IO when the leading edge of the first sheet of paper reaches the paper feed roller luff, and the second sheet of paper is left in a loop. Since there is no paper, the process proceeds as n 30-+n 26-+n 27→n1B, and the paper is not fed after the paper is detected in S4.

In this embodiment, after S4 detects the paper by comparing Ll and Ll, the paper is further fed for 12 hours to prevent the leading edge of the next paper from being left in a loop. The paper feeding roller may be rotated by detecting the loop state of the paper.

(g) Effects of the Invention As described above, according to the present invention, the leading edge of the next sheet is no longer left in a looped state, and this prevents the leading edge of the sheet from forming a loop, thereby preventing the feeding of the next sheet. It is possible to prevent jams and transfer defects.

[Brief explanation of drawings]

1(A) to 1(C) are flowcharts showing the processing procedure of a large-capacity paper feed cassette according to an embodiment of the present invention;
The figure is a block diagram of the control section of the cassette, FIG. 3 is a perspective view of the paper feeding section, and FIG. 4 is a perspective view of the regulating plate moving mechanism. Figures 5 to 7 are diagrams showing the rollers that make the movement of the regulation plate smooth. Figure 5 is a perspective view, Figure 6 is a front view, and Figure 7 (A) is a state in which the regulation plate is locked. Side view of Figure 7 (
B) is a side view of the unlocked state. Moreover, FIG. 8 is a cross-sectional view showing the locking mechanism of the lower part of the regulating plate, with FIG. 8(A) showing the locked state and FIG. 8(B) showing the unlocked state. Figure 9 is an external view of the lock release member that unlocks the regulation plate, Figure 10 is a perspective view showing the main parts of the sensor that detects the paper width, and Figure 11 shows the position of the preliminary paper feed roller. 12 are cross-sectional views of the vicinity of the auxiliary roller. Fig. 14 is a perspective view of the locking mechanism section below the regulation plate, Fig. 13 is a perspective view of the regulation plate of the large capacity cassette/I- and the reinforcing plate portion that holds the regulation plate, and Fig. 15 is the large capacity cassette lift. FIG. 16 is a schematic front view of a copying machine equipped with a large-capacity cassette. 4 - hopper stand, 6 - guide plate, 7 - paper feed roller, 8 - preliminary paper feed roller, 9 - auxiliary roller.

Claims (1)

[Claims] (1) In a paper feeding device that conveys paper placed on a hopper stand to a paper feed roller of an image forming apparatus main body by rotation of a preliminary paper feed roller provided at the tip of the hopper stand, the sheet is placed on the hopper stand. means for detecting the paper length of the loaded paper in the conveyance direction; a comparison means for comparing the length from the tip of the hopper table to the paper feed roller with the paper length; 1. A paper feeding device comprising: means for continuing rotation of a preparatory paper feeding roller for a predetermined period of time after the paper reaches the paper feeding roller when the paper is determined to be short.