JPH04129934A - Cut paper sheet supply method and device therefor - Google Patents

Abstract

PURPOSE:To supply paper sheet stably by setting the amount of driving a roller driven by a preliminary driving means so that a paper sheet to be sent out next may stand by for next sending-out action in such status that its front edge has passed over a paper separating claw. CONSTITUTION:A paper sheet separating claw 16 is engaged with the feed edge of a paper sheet pile S. A feed roller 14 frictionally engaged with the upper surface of the paper pile S is rotated to send out paper sheets one after another from the upper side of the paper pile S. In this case, when a paper sheet is sent out from the paper pile S, the feed roller 14 is driven until the rear end of the sheet leaves the feed roller 14 and, when feed of the sheet is completed, a sheet to be sent out next is given in advance initial sending-out action by driving the feed roller 14. This makes a sheet stand by for next sending-out action in such status that its front edge has passed over the paper separating claw 16.

Description

[Detailed Description of the Invention] [Summary] A paper feeding method and device for cut paper that adopts a claw separation method, which can be applied particularly to printers, copying machines, etc. To provide a paper feeding method and device capable of economically solving both the slipping problem that may occur between paper sheets when they are transported by transport rollers, and the folding problem that may occur at both ends of the paper to be fed next. With the purpose of In the paper feeding method, when paper is fed out from a paper stack, the feeding roller is driven until the trailing edge of the paper comes out of the feeding roller, and when the feeding of the paper is completed, it is fed in advance to the next sheet to be fed. A paper feeding method characterized in that the initial movement is provided by driving a feeding roller, whereby the paper is made to stand by for the next feeding operation in a state where its leading edge has passed over a paper separating claw. The paper feeding device that implements the paper feeding method includes a paper size determining means for determining the size of the paper to be fed, and a feeding drive amount of the feeding roller in accordance with the judgment of the paper size judging means. 5) A driving amount determining means, a paper feeding detection means for detecting whether or not the paper is completely fed out from the paper stack, and a paper feeding detection means for detecting whether the paper is completely fed out from the paper stack. and a preliminary driving means for preliminarily driving a feeding roller to give an initial feeding motion to the next sheet of paper to be fed out in advance when the paper is detected. A paper feeding device is configured that includes a paper size determining unit that determines the size, and a feeding drive amount determining unit that determines the feeding drive amount of the feeding roller in accordance with the determination by the paper size determining unit.

[Industrial application field]

The present invention relates to a paper feeding method and device for cut paper that employs a claw separation method, and more particularly to a paper feeding method and device that can be applied to printers, copying machines, and the like.

[Prior Art] In a cut paper feeding method that employs a claw separation method, a paper separation claw is arranged at the feeding edge of a paper stack, and a feeding roller frictionally engaged with two surfaces of the paper stack. As a result, the paper is fed one by one from the top side of the paper stack. Referring to FIGS. 10(a) and 10(b), there is shown a paper feed cassette that employs a claw separation method, and this paper feed cassette includes a rectangular tray 10 that accommodates a stack S of paper, and a rectangular tray 10 that accommodates a stack S of paper. Rectangular tray 1
A pair of feed rollers 14.14 are disposed close to and above one side wall 12 of the o, and paper separating claws 16 are disposed at both ends of the o side wall 12. Figure 10(b)
As shown in FIG. 2, a movable bottom plate 18 is disposed at the bottom of the rectangular tray 1o and is disposed close to one side wall 12 of the rectangular tray 1o, and one end of the movable bottom plate 18 is lifted by an elastic spring 20. As a result, one end side of the paper stack S, that is, the feeding end side, is pushed up, whereby the upper surface of the feeding end of the paper stack S is elastically pressed against the feeding roller 14 and brought into frictional engagement. . On the other hand, the upper edge of the dispensing end of the paper stack S serves as the dispensing edge and is engaged with the pair of paper separating claws 16 . The payout rollers 14 are fixed on a common shaft 22, which is connected to a suitable drive motor, for example via a clutch (not shown).

During paper feeding, the drive motor is always in a driving state, and the rotation of the feed roller 14 and its stop are controlled by turning on/off the clutch provided between the drive morph and the shaft 22.
Done by off. When the clutch is turned on, the feed roller 14 is driven to rotate in the direction of arrow A (FIG. 8(a)), and as a result, the uppermost sheet of paper from the paper stack S is brought into frictional contact with the feed roller 14. At this time, only the leading edge of the paper passes over the paper separating claw 16. That is, when the topmost paper is fed out, the paper below it also tends to be fed out due to friction with the topmost paper, but the feeding force is smaller than that of the topmost paper, so The lower paper cannot get over the paper separation claw 16, and only the uppermost paper can be fed out. In short, in paper feeding using the claw separation method, the cooperation between the feeding roller 14 and the paper separating claw 16 can ensure that the sheets are fed one by one from the paper stack S.

[Problem to be solved by the invention]

The sheet of paper fed out as described above is sent toward a pair of conveyance rollers (not shown), and then guided by the conveyance rollers to a recording section of a printer, copying machine, or the like. In this case, the rotational drive of the feeding roller 14 is temporarily stopped when the leading edge of the feeding paper reaches the transport roller, but at this time, the trailing edge portion of the feeding paper remains in the paper feed cassette. , it has not come out from the feeding roller 14. Therefore, when the feed sheet is conveyed by the conveyance roller and the trailing edge portion of the feed sheet is pulled out from the feed roller 14, the feed roller 14 rotates with it. Since such a continuous rotation load is relatively large, slippage may occur between the feeding sheet and the conveying roller. Of course, if slipping occurs, the feeding speed of the paper will become uneven, and
Not only will it not be possible to record an image at an appropriate location on the fed paper, but the recorded image may also be distorted.

In order to eliminate such problems, it has also been proposed to continue rotating the feed roller 14 until the trailing edge of the feed sheet completely leaves the feed roller 14.

However, in that case, when the trailing edge of the sheet of paper comes out of the feed roller 14, the feed roller 14
engages the next sheet to be dispensed, so that the sheet is subjected to an instantaneous dispensing action, at which time both edges of the sheet are brought into contact with the paper separating pawls 16 (see FIG. 8 et al.). It will be bent as shown at B. If such paper is fed immediately, the folding of the edges is not a problem, but if the paper is left alone (i.e., the paper feed operation is stopped), the folding of the edges The bending will be in a plastically deformed state, which may cause various problems. For example, a sheet of paper may get caught in a conveyance path due to folds at both ends, resulting in a so-called jam, or the entire sheet of paper may be creased and wrinkled, resulting in missing recorded images.

In order to solve the following problems, it has been proposed to use a feed roller with a built-in one-way clutch. In FIG. 8C, such a payout roller is designated by the reference numeral 24 and is mounted on the shaft 22 via a one-way clutch 26. When the shaft 22 rotates in the direction of arrow A, the one-way clutch 26 transmits its rotational force to the feeding roller 24.
When the feeding roller 24 itself rotates in the direction indicated by the arrow, the rotational force thereof is not transmitted to the shaft 22. According to such a configuration, after the rotational drive of the feeding roller 24 is stopped while the trailing edge side portion of the feeding sheet remains in the paper feed cassette, the trailing edge side portion of the feeding sheet is removed from the feeding roller 24. When the sheet is pulled out, the continuous rotational load on the feeding roller 24 is greatly reduced, so no slippage occurs between the feeding roller and the conveyance roller. However, when paper is fed at a high speed, even if the clutch provided between the drive motor and the shaft 22 is turned off, the feed roller 24 continues to rotate due to its inertia, resulting in A feeding action is applied to the paper to be fed out, and both ends of the paper are bent due to collision with the paper separating claw 16 (eighth
Figure (b)). Therefore, even if a feed roller with a built-in one-way clutch is used, the above-mentioned problems are not completely solved. Furthermore, the feed-out roller with a built-in one-way clutch is considerably more expensive than the feed-out roller 14 shown in FIGS. 8(a) and 8(b), and its use poses an economical problem.

As another solution, it has been proposed to use a substantially half-moon-shaped feeding roller 28 as shown in FIG. 8(d).

Such a feeding roller 28 applies a feeding motion to the paper with its approximately half-moon-shaped arc portion, and its rotational drive is stopped when its chord portion is directed downward. When such a substantially half-moon-shaped feeding roller 28 is used, both of the above-mentioned problems can be solved. However, in the case of the approximately half-moon-shaped feeding roller 28, the sheet can only be fed out once, and therefore only the paper feeding amount corresponding to the length of the substantially half-moon-shaped arc portion of the feeding roller 28 can be obtained. The problem is that it doesn't work. This is because although it is possible to increase the amount of paper fed out by rotating the feeding roller 28 one or more revolutions, the chord part of the feeding roller 28 cannot give a feeding motion to the paper, and therefore, the amount of paper feeding is increased. This is because feeding cannot be performed stably. In short, when using the approximately half-moon shaped feeding roller 28,
Because a sufficient amount of paper cannot be fed out, the number of transport rollers installed to transport the paper from the paper cassette to the recording section of the printer or copier increases, which increases the overall size of the printer or copier. However, the manufacturing cost of printers and copiers increases due to the increase in the number of parts.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method and apparatus for feeding cut paper, and to solve the problem of slippage that may occur between feeding rollers when the paper is fed by conveyance rollers, as well as the slipping problem that may occur at both ends of the sheet to be fed next. It is an object of the present invention to provide a cut paper feeding method and an apparatus therefor that can economically solve both the problems of folding and folding.

[Means to solve the problem]

According to the present invention, the following paper feeding method is configured as a means to solve the problem. That is, in the paper feeding method according to the present invention, as in the case of the conventional paper feeding method that adopts the mold separation method, a paper separation claw is engaged with the feeding edge of the paper stack, and friction is applied to the top surface of the paper stack. The engaged feed-out rollers are rotated, thereby feeding out the sheets one by one from the top side of the paper stack. According to the invention,
In such a paper feeding method, when paper is fed out from the paper stack, the feeding roller is driven until the trailing edge of the paper comes out of the feeding roller, and when feeding of the paper is completed, the next sheet to be fed out is driven. The present invention is characterized in that an initial feeding operation is given to the paper in advance by driving a feeding roller, whereby the paper is made to stand by for the next feeding operation in a state in which the leading edge of the paper passes over the paper separating claw. be done.

Further, according to the present invention, a paper feeding device as shown in FIG. 1(a) is configured as a necessary means for solving the problem.

In this paper feeding device, as in the case of conventional paper feeding devices that employ the mold separation method, a paper separation claw is engaged with the feeding edge of the paper stack and frictionally engaged with the upper surface of the paper stack. The feed roller is rotated, thereby feeding out the sheets one by one from the top side of the paper stack. According to the present invention, such a paper feeding device includes components as shown in FIG. 1(a). That is, it includes a paper size determining means, a feeding drive amount determining means, a paper feeding detecting means, and a preliminary driving means. The paper size determining means determines the size of the paper to be fed, and the feeding drive amount determining means determines the feeding drive amount of the feeding roller according to the judgment of the paper size judging means, and the feeding drive amount is determined based on the paper stack. When the paper is fed out from the body, the trailing edge of the paper comes out of the feeding roller.

The paper feed detection means detects whether the paper is completely fed out from the paper stack, and the preliminary drive means detects whether the paper is completely fed out from the paper stack when the paper feed detection means detects that the paper is completely fed out from the paper stack. The feeding roller is preliminarily driven in order to give an initial feeding motion to the paper to be fed next, and the driving amount by which the feeding roller is driven by this preliminary driving means is such that the sheet to be fed next It is assumed that the paper waits for the next feeding operation in a state in which the edge is pushed over the paper separating claw.

Further, according to the present invention, as a means for solving the problem, a paper feeding device as shown in FIG. 1(b) is configured.

In this paper feeding device, as in the case of conventional paper feeding devices that adopt the mold separation method, a paper separation claw is engaged with the feeding edge of the paper stack, and frictionally engages the two sides of the paper stack. The fed-out roller is rotated, thereby feeding out the sheets one by one from the top side of the paper stack. According to the present invention, such a paper feeding device includes components as shown in FIG. 1(b). That is, it includes a paper size determining means and a feeding drive amount determining means. The paper size determining means determines the size of the paper to be fed out, the feeding drive amount determining means determines the feeding drive amount of the feeding roller according to the judgment of the paper size judging means, and the feeding driving amount is determined based on the paper stack. Even after the trailing edge of the paper has come out of the feeding roller when the paper is fed out from the feed roller, an initial feeding motion is applied in advance to the next sheet of paper to be fed out, so that the leading edge of the paper is The paper is made to stand by for the next feeding operation in a state where the paper is allowed to pass over the paper separation claw.

[Effect]

As is clear from the above configuration, in the paper feeding method and its paper feeding device according to the present invention, when the paper is fed out from the paper stack, the trailing edge of the paper is driven until it comes out of the feeding roller. , when the paper is conveyed by the conveyance rollers, no slip occurs during the conveyance. Further, when the feeding of the paper is completed, the paper to be fed next is given an initial feeding motion in advance by driving the feeding roller, so that the paper moves its leading edge over the paper separating claw. Therefore, even if the leading edge of the paper is bent due to collision with the paper separating claw, the folded state will not remain for a long time.

〔Example〕

Next, embodiments of a paper feeding method and a paper feeding device according to the present invention will be described with reference to FIGS. 2 to 7 of the accompanying drawings.

FIG. 2 schematically shows an electrophotographic printer to which the present invention is applied. This electrophotographic printer is equipped with a photosensitive drum 30, and around the photosensitive drum 30 is a pre-charger 32,
A developing device 34, a transfer device 36, a cleaner 38, etc. are arranged in this order. During the recording operation, the photosensitive drum 30 is rotated in the direction of the arrow shown in the figure, and first, a charged area is formed on the photosensitive surface of the photosensitive drum 30 by the charger 32, and a laser beam scanning optical unit 40 is applied to the charged area. An electrostatic latent image is written. In FIG. 2, the scanning laser beam emitted from the laser beam scanning optical unit 40 is indicated by the reference symbol LB. Next, the electrostatic latent image is developed into a visible image using a developer, so-called toner, by a developing device 34, and the developed toner image is transferred onto a recording sheet by a transfer device 36. This recording paper is stored in the paper feed cassette 42.
The paper feed cassette 42 is substantially the same as that shown in FIGS. 8(a) and 8(b). Note that the individual components of the paper feed cassette 42 are indicated by the same reference numbers as those used in FIGS. 8(a) and 8(b).

The recording paper fed out from the paper feed cassette is guided to a first pair of conveyance rollers 44.44, and then passed through a second pair of conveyance rollers 46.46 to the photosensitive drum 30 and the transfer device 3.
The developed toner image is introduced at a predetermined timing between 6 and 6, so that the developed toner image is transferred to the recording paper at a predetermined position. The recording paper with the transferred toner image is placed on the photosensitive drum 3.
0 and guided to a heat fixing device (heat roller) 48, where the transferred toner image is thermally fixed onto the recording paper.

After thermal fixing, the recording paper is discharged onto a tray 52 via a discharge roller 50. On the other hand, the toner remaining on the photosensitive surface of the photosensitive drum 30 without being transferred to the recording paper side during the transfer of the developed toner image is cleaned by the cleaner 38, and a charged area is again formed by the charger on the cleaned surface.
The process described above is repeated.

Referring to FIG. 3, there is shown a paper feeding device applied to the electrophotographic printer shown in FIG. be done. As is clear from Figure 3, the microcomputer is a central processing unit (CPU).
) 54a, a read-only memory (ROM) 54b that stores paper feeding programs, constants, etc., and a writable/readable memo IJ (RAM) that stores temporal data, etc.
54c and a human output interface (Ilo) 54d. The control circuit 54 also controls the operation of the electrophotographic printer shown in FIG. 2, and therefore the ROM 54c also includes its operation program.

The paper feed device includes a microswitch 56, which is provided at the installation part of the paper feed cassette 42, and in this embodiment, it is turned on when the A4 size paper feed cassette is installed. and is turned off when a B4 size paper feed cassette is installed. Regarding the on/off operation of the microswitch 56, for example, a protrusion that engages with the detection part of the microswitch 5G is provided on the A4 size paper feed cassette, and the B4 size paper feed cassette is can be achieved by eliminating such protrusions. The output from the microswitch 56 is input to the control circuit 54 via l1054d, thereby making it possible to determine the size of paper to be fed. It goes without saying that when paper feed cassettes for three or more paper sizes are used, it is possible to determine which size paper is fed by increasing the number of microswitches. Alternatively, a single paper cassette capable of accommodating various paper sizes may be used, in which case a partition that can be moved according to the paper size may be provided in the paper cassette. Since a wall is provided, the paper size can be determined by activating any one of a plurality of microswitches using a protrusion that moves together with the partition wall.

The feeder also includes a sensor 58, which may consist of a photodetector or a microsinch, and in this embodiment the sensor 58 approaches the first pair of transport rollers 44, 44 as shown in FIG. It detects paper passing through it. For example, when the leading edge of the unrolled paper reaches the sensor 58, the output signal output therefrom changes from a low level to a high level, and the trailing edge of the unrolled paper reaches the sensor 58.
8, the output signal goes from high level back to low level again. Sensor 58 is connected to T1 via fall detector 60.
054d, and when the output signal from the sensor 58 changes from a high level to a low level, a fall detector 60
A pulse is output from T1054d, and this pulse is taken into the control circuit 54 via T1054d. In short, the control circuit 54 determines that the fed paper has finished passing the sensor 58 when a pulse is output from the fall detector 60.

The control circuit 54 controls the drive of a drive motor 64 via a drive circuit 62, which drive motor 64 is operatively connected to the payout roller 14 (more precisely, the shaft 22) via a clutch 66. Further, the control circuit 54 controls on/off of the clutch 66 via a drive circuit 68. During the feeding operation, the drive motor 4 is continuously driven, and the rotation of the feeding roller 14 and its stopping are controlled by turning on/off the clutch 66.
Controlled by off.

Next, the operation of the paper feeding device shown in FIG. 3 will be explained with reference to the paper feeding routine shown in FIG. The paper feeding routine shown in FIG. 4 is executed every time a print command is output from a microcomputer, word processor, etc. connected to the electrophotographic printer shown in FIG.

In step 401, a drive signal is output from the control circuit 54 to the drive circuit 64 via the l1052d, thereby driving the drive motor 64. Then step 402
Then, it is determined whether the microswitch 56 is on or off. As mentioned above, the micro switch 5
When the microswitch 6 is in the on state, the paper feed cassette 42 is for A4 size, and when the microswitch 56 is in the off state, the paper feed cassette 42 is for B4 size.

If the microswitch 56 is on, step 4
03, where the drive time TA of the feeding roller 14 is set. This drive time TA is set as a constant in the ROM54.
b, which is stored in the feed roller 14
This corresponds to the time from when the A4 size sheet is fed out by starting its rotation until the trailing edge of the A4 size sheet comes off the feed roller 14. Next,
The process advances to step 404, where it is determined whether there is a paper feeding command. This paper feed command is issued, for example, when the laser beam scanning optical unit 40 writes an electrostatic latent image on the photosensitive drum 30 based on the record data for -page.

When a paper feed command is issued in step 404, step 4
05, where a drive signal is output from the control circuit 54 to the drive circuit 66 via T1052d, which turns on the clutch 66 and starts driving the feeding roller 14. That is, feeding of A4 size paper from the paper feed cassette 42 is started. In step 406, it is determined whether the driving time TA has elapsed. As described above, when the driving time TA has elapsed, the trailing edge of the A4 size paper that had formed during the feeding operation will come out of the feeding roller 14. When the driving time TA has elapsed, the process proceeds to step 407, where the clutch 66 is turned off and the rotational drive of the feeding roller 14 is stopped.

Next, the process proceeds to step 408, where it is determined whether a pulse is output from the falling edge detector 60 or not. That is, it is determined whether the A4 size paper fed out from the paper feed cassette 42 has finished passing through the sensor 58 or not. When the pulse is output from the detector 60, the process proceeds to step 409, where the clutch 66 is turned on again, and the feeding roller 14 is driven to rotate again, and then, in step 410, time T elapses. It is determined whether or not time T has elapsed. When the time has elapsed, the process advances to step 411, where the clutch 66 is turned off and the rotational drive of the feeding roller 14 is stopped.

Time T. is much shorter than the time TA, and while the process proceeds from step 409 to step 411, only the initial feeding motion is given to the A4 size paper to be fed next, and the A4 size paper is moved toward its leading edge. Then, the paper is allowed to pass over the paper separating claw 16 and is kept in a state of standby for the next feeding operation. In FIG. 5, the feeding roller 14 is moved at a time T. The state immediately after being driven is shown, and in the figure, reference numeral 70 indicates the A4 size sheet to be fed next.

As is clear from FIG. 5, the leading edge of the A4 size paper 70 has passed over the paper separation claw 16 and protruded from the paper feed cassette 42.

In step 412, it is determined whether printing is finished. In other words, it is determined whether or not the sending of data to be recorded from the microcomputer or word processing sensor connected to the electrophotographic printer has been completed. If the sending of the data to be recorded has not been completed, step 40
4, the A4 size paper is fed out again.

On the other hand, if the sending of the data to be recorded has been completed, the routine proceeds to step 413, where the drive of the drive moculator 4 is stopped, and then the routine ends.

If the microswitch 56 is off in step 402, a B4 size sheet will be fed out, so in step 414 the driving time TB of the feeding roller 14 is set. Steps 415 to 423 correspond to steps 404 to 412, respectively, and feeding of B4 size paper is performed in the same manner as for A4 size paper. That is, except that the driving time TB is set for the feeding roller 14 according to the B4 size paper.
The contents executed in steps 415 to 423 are the same as the contents executed in steps 404 to 412.

If the paper is fed out in the manner described above, when the paper is fed out from the paper stack S, the paper is driven until the trailing edge of the paper comes out of the feeding roller 14.
When the paper is transported by the first pair of transport rollers 44, 44, no slip occurs between them.

Further, when the feeding of the paper is completed, the paper to be fed next is given an initial feeding motion in advance by driving the feeding roller 14, thereby causing the paper to move over the paper separating claw 16 with its leading edge. Since the paper is kept in a state of being held in place for the next feeding operation, even if the leading edge of the paper is bent due to collision with the paper separating claw 16, the folded state will not be left for a long time. do not have.

Note that the paper stack is accommodated in the paper feed cassette 42,
When it is installed in an electrophotographic printer, the leading edge of the top paper in the paper stack is not in a state of protruding from the paper feed cassette 42 as shown in FIG. In this case, the operator may manually pull out the leading edge of the top sheet of paper, or the operator may pull out the top paper by hand, or the feed roller 14 may be moved for a time T immediately after the paper feed cassette 42 is installed. Alternatively, the uppermost sheet may be given an initial feeding motion by rotationally driving the uppermost sheet.

In the embodiment described in FIGS. 3 and 4, the sensor 58
is located adjacent to the first pair of transport rollers 44.44, but a sensor 58 is located at any point along the paper path from the paper feed cassette 42 to the first pair of transport rollers 44.44. Needless to say, it is possible to place

In the embodiment described above, after the sensor 58 confirms that the paper has been completely fed out of the paper feed cassette,
The feeding roller 14 is preliminarily moved for a time T to give an initial feeding motion to the sheet to be fed next. However, in order to feed out the paper, the feed roller 14 is rotated for a time TA or TB, and then continues for a time T. Alternatively, the feeding roller 14 may be rotationally driven by the same amount as the initial movement of feeding the sheet to be fed next. This latter paper feeding operation will be explained with reference to the paper feeding routine shown in FIG. It goes without saying that the sensor 58 and fall detector 60 shown in FIG. 3 are not required in this sheet feeding operation.

In step 601, a drive signal is outputted from the control circuit 54 to the drive circuit 64 via the l1052d, thereby driving the drive mocro 4. Then step 602
Then, it is determined whether the micro-sinch 56 is on or off. As mentioned above, the micro switch 5
When the microswitch 6 is in the on state, the paper feed cassette 42 is for A4 size, and when the microswitch 56 is in the off state, the paper feed cassette 42 is for B4 size.

If the microswitch 56 is on, step 6
03, where the drive time MA of the feeding roller 14 is set. This drive time MA is the time TA and T explained in FIG. Corresponds to the sum of The driving time MA is stored as a constant in the ROM 54b. Next, the process advances to step 604, where it is determined whether there is a paper feeding command. This paper feed command is issued, for example, when the laser beam scanning optical unit 40 writes an electrostatic latent image on the photosensitive drum 30 based on the record data for -page.

When a paper feed command is issued in step 604, step 6
05, where a drive signal is output from the control circuit 54 to the drive circuit 66 via l1052d, thereby turning on the clutch 66 and starting to drive the feeding roller 14. That is, feeding of A4 size paper from the paper feed cassette 42 is started. In step 406, it is determined whether the driving time MA has elapsed. Drive time MA
After , the process proceeds to step 407, where the clutch 66 is turned off and the rotational drive of the feeding roller 14 is stopped. As mentioned above, the drive time MA is the time TA and T. When the time TA has elapsed, the trailing edge of the A4 size paper that is being fed out moves to the feeding roller 14.
After that time T. While this period has elapsed, an initial feeding operation is given to the A4 size paper to be fed next.

As a result, the A4 size paper to be fed out next is kept waiting for the next feeding operation with its leading edge passing over the paper separating claw 16. FIG. 7 shows the state immediately after the driving time MA has elapsed,
In the figure, reference number 72 indicates an A4 size paper fed out from the paper feed cassette 42, and reference number 74 indicates an A4 size paper to be fed next.

In step 608, it is determined whether printing is finished. That is, it is determined whether the sending of data to be recorded from the microcomputer or word processor connected to the electrophotographic printer has been completed. If the sending of the data to be recorded has not been completed, step 60
4, the A4 size paper is fed out again.

On the other hand, if the sending of the data to be recorded has been completed, the routine proceeds to step 609, where the driving of the drive motor 64 is stopped, and then the routine ends.

If the microswitch 56 is off in step 602, a B4 size sheet will be fed out, so in step 610, the driving time MB of the feeding roller 14 is set. This drive time M[l is the time Tr+ and T explained in FIG.

Corresponds to the sum of Steps 611 to 615 correspond to steps 604 to 608, respectively,
B4 size paper is fed out in the same manner as A4 size paper. That is, except that the driving times M and l are set for the feeding roller 14 according to B4 size paper.
The contents executed in steps 610 to 615 are the same as the contents executed in steps 604 to 608.

If the paper is fed out in the manner described above, when the paper is fed out from the paper stack S, the paper is driven until the trailing edge of the paper comes out of the feeding roller 14.
When the paper is transported by the first pair of transport rollers 44, 44, no slip occurs between them.

In addition, the paper to be fed next is given an initial feeding operation in advance by driving the feeding roller 14, so that the paper is allowed to move over the paper separating claw 16 with its leading edge before the next feeding operation. Therefore, even if the leading edge of the paper is bent due to collision with the paper separating claw 16, the folded state will not remain for a long time.

Although the above-described embodiments have been described in connection with an electrophotographic printer, it goes without saying that the paper feeding device according to the present invention can also be applied to other types of printers, copying machines, and the like.

〔Effect of the invention〕

As is clear from the above description, the paper feeding method and its paper feeding device according to the present invention solve the problems associated with the conventional paper feeding method and its device that adopt the claw separation method, that is, the paper is fed out by a conveying roller. This solves both the problems of slippage that may occur between the sheets when they are conveyed, as well as the folding problem that may occur at both ends of the paper to be fed next, so that not only can the paper be stably fed, but also ,
Good recording on the paper can also be ensured. Further, in the paper feeding method and the paper feeding device according to the present invention, conventional and inexpensive mechanical components of the paper feeding cassette itself can be used, so that the present invention can be implemented at low cost.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the present invention, FIG. 2 is a schematic diagram of an electrophotographic printer embodying the present invention, FIG. 3 is a block diagram showing a first embodiment of a paper feeding device according to the present invention, and FIG. Figure 4 is the third
FIG. 5 is a partially enlarged view of the paper feed cassette partially shown in FIG. 2, and the paper feeding routine shown in FIG. FIG. 6 is a reference diagram for supplementing the explanation of the routine, and FIG. 6 is a paper feeding routine for explaining the operation of the second embodiment of the paper feeding device according to the present invention. FIG. 7 is a diagram similar to FIG. 5. 8(a) is a perspective view showing a conventional example of a paper feed cassette that adopts the claw separation method, and FIG. 8(b) is a reference diagram to supplement the explanation of the paper feeding routine in FIG. 6. is shown in Figure 8 (a
), FIG. 8(C) is a partial vertical sectional view of the paper feed cassette of
Fig. 8(d) is a partial longitudinal cross-sectional view similar to Fig.
) is a partial vertical cross-sectional view similar to FIG. 8 et al.), and is a diagram showing yet another conventional example of a paper feed cassette that employs the claw separation method. 10... Rectangular tray, 12...-side wall, 14...
- Feeding roller, 16... Paper separation claw, 18... Movable bottom plate, 20... Elastic spring, 42... Paper feed cassette, 54... Control circuit, 56... Micro switch,
58...sensor, 60...falling detector, 62...
... Drive circuit, 64... Drive morph, 66... Clutch, 68... Drive circuit.

Claims (1)

[Claims] 1. A paper separating claw (16
) and rotates a feeding roller (14) frictionally engaged with the top surface of the paper stack (S) to feed out the sheets one by one from the top surface of the paper stack (S). In the paper feeding method, when the paper is fed out from the paper stack (S), the feeding roller is driven until the trailing edge of the paper comes out of the feeding roller, and when feeding of the paper is completed, the next The paper to be fed is given an initial feeding motion in advance by driving the feeding roller (14), so that the paper moves its leading edge to the paper separating claw (16).
A method for feeding cut paper, characterized in that the cut paper is made to stand by for the next feeding operation in a state where the cut paper is allowed to cross over. 2. A paper separation claw (16) is attached to the feeding edge of the paper stack (S).
) and rotates a feeding roller (14) frictionally engaged with the top surface of the paper stack (S) to feed out the sheets one by one from the top surface of the paper stack (S). A paper feeding device comprising: a paper size determining means (402) for determining the size of the paper to be fed; and a feeding drive amount of the feeding roller (14) according to the judgment of the paper size judging means (402). and a feed-out drive amount determination means (403; 414) for determining the feed-out drive amount, the paper stack (S)
When the paper is fed out from the sheet, the trailing edge of the paper comes out of the feeding roller (14), and further, it is detected whether or not the paper is completely fed out from the paper stack (S). Feeding detection means (408;
419), and when the sheet feeding detection means (408:419) detects that the sheet is completely fed out from the paper stack (S), giving an initial feeding operation to the sheet to be fed next in advance. The feed roller (14)
) for preliminary driving means (409, 41
0, 411; 420, 421, 422), and the preliminary driving means (409, 410, 411; 420
, 421, 422)
The driving amount is such that the paper to be fed out next waits for the next feeding operation with its leading edge passing over the paper separating claw (16). A cut paper feeding device featuring: 3. A paper separation claw (16
) and rotates a feeding roller (14) frictionally engaged with the top surface of the paper stack (S) to feed out the sheets one by one from the top surface of the paper stack (S). A paper feeding device comprising: a paper size determining means (602) for determining the size of the paper to be fed; and a feeding drive amount of the feeding roller (14) according to the judgment of the paper size judging means (602). and a feed-out drive amount determination means (603; 610) for determining the feed-out drive amount, the sheet stack (S)
Even after the trailing edge of the paper comes out of the feed roller (14) when the paper is fed out from the feed roller (14), an initial feeding motion is given in advance to the next sheet to be fed, so that the leading edge of the paper is A cut paper feeding device characterized in that the cut paper feeding device is made to stand by for the next feeding operation in a state where the edge of the cut paper passes over the paper separation claw (16).