JPH09100041A - Sheet feeder and image forming device provided therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accelerate a rate of sheet feeding. SOLUTION: Sheets 11 on a sheet loading means 21 are delivered piece by piece by each of pickup rollers 1 which are supported by an arm 2 free of rotation and linked up with a driving motor 6 via two driving belts 4 and 5, and they are rotated by this motor 6. In addition, the arm 2 supporting these pickup roller 1 is rotated by a driving means consisting of a rotation supporting lever 7, a power transmission means 22 and a stepping motor 10, making the pickup rollers 1 move between a feeding position (a position in contact with the sheet 11) and a standby position (a position separated as far as the specified distance from the sheet 11). A travel speed of this pickup roller 1 is accurately controlled, with no variation, by a central processing unit 20 connected to the stepping motor 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image forming apparatus such as an electronic copying machine, a printer, a facsimile, and the like, and a sheet feeding device for feeding a sheet such as a document or a recording sheet, and a sheet feeding device. The present invention relates to a provided image forming apparatus.

[0002]

2. Description of the Related Art As a generally known sheet feeding apparatus, there is a retard roller type sheet feeding apparatus including a pickup roller, a conveying roller, a separation roller (reverse rotation roller) and the like. This retard roller type sheet feeding apparatus is generally used because it can stably separate and feed a sheet such as recycled paper which is likely to be double fed.

FIG. 6 shows such a conventional retard roller type sheet feeding device.

In this retard roller type sheet feeding device, a pickup roller 13 is supported by a rotatable arm 12 and can be moved between a sheet feeding position (A) and a standby position (B). There is. Then, at the paper feed position where the pickup roller 13 comes into contact with the uppermost surface of the sheet, the pickup roller 13 rotates counterclockwise in the figure, so that the uppermost sheet is sent out by the pickup roller 13 in the right direction in the figure. Be done.

The sheets sent by the pickup roller 13 enter the nip portion between the conveying roller 14 and the separating roller 15 and are separated here one by one. The conveyance roller 14 receives a driving force from a driving source (not shown), rotates, and conveys the sheet in a direction in which the sheet advances (rightward in the figure). On the other hand, the separation roller 15 is connected to a drive source (not shown) via a torque limiter (not shown) so as to rotate in a direction in which the sheet is prevented from advancing, and is rotationally driven by the drive source (not shown). ing.

When one sheet enters the nip portion between the conveying roller 14 and the separating roller 15, a large rotational resistance acts on the separating roller 15, and the torque limiter causes the driving source to move to the separating roller 15. The transmission of the driving force is cut off, and the separation roller 15 follows the transport roller 14. On the other hand, when two or more sheets enter the nip portion between the transport roller 14 and the separation roller 15, a relatively small rotational resistance acts on the separation roller 15, and the separation roller 15 prevents the sheet from advancing. Rotation in the direction to prevent the sheet on the separation roller 15 side from being conveyed. As a result, only the sheet on the side of the transport roller 14 is sent out by the transport roller 14.

When the sheet is sent out by the transport roller 14, the pickup roller 13 moves from the sheet feeding position to the standby position in preparation for the next sheet feeding. The pickup roller 13 turns on / off the solenoid 16.
The arm 12 which is rotationally controlled by means of this allows the arm 12 to move between the paper feed position and the standby position. In this conventional example, the pickup roller 13 is made to stand by at the standby position when the solenoid 16 is in the suction (ON) state, and when the solenoid suction state is released (OFF), the pickup roller 13 is in the standby state. Move from position to feed position. still,
As for the configuration of the transport roller and the separation roller, there is also a configuration in which the transport roller and the separation roller are arranged in a comb shape in the longitudinal direction of the sheet (direction perpendicular to the sheet feeding direction) and the separation roller is not provided with a torque limiter. is there.

[0008]

However, in the above-mentioned conventional example, as described above, the solenoid 1 is used to move (switch) the pickup roller 13 between the feeding position and the standby position.
6, the solenoid 16 generates an attractive force by a magnetic force to attract the iron core, so that the electrical response of the solenoid 16 varies by about 100 msec.
That is, when the pickup roller 13 is switched from the standby position to the feeding position, a variation of about 100 msec occurs.

In a high-speed sheet conveying machine (electrophotographic copying machine) aiming for high productivity, in consideration of variations in the operation of the solenoid 16, it is necessary to set a large sheet interval during continuous sheet feeding (for example, sheet). If the feeding speed is set to 500 mm / sec, a 50 mm sheet advances in 100 msec), which is an obstacle to speeding up sheet feeding.

In the conventional example as described above, when the solenoid 16 is turned off, the pickup roller 13 falls on the sheet S by its own weight. At this time, if the pickup roller 13 collides with the sheet S, the pickup roller 13 is picked up. The roller 13 causes a bounce due to the rubber elasticity of the roller material. As a result, in the above-described conventional example, in the case of continuous sheet feeding, the next sheet is fed after waiting for the bouncing of the pickup roller 13 to subside (decrease), which requires a long time for the sheet feeding interval. In other words, the sheet feeding speed becomes slow, and it has been difficult to meet the demand for higher sheet feeding speed.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a sheet feeding device capable of solving the problems of the conventional example and speeding up the sheet feeding, and an image forming apparatus equipped with the sheet feeding device.

[0012]

A sheet feeding device of the present invention is a sheet stacking means for stacking sheets, a feeding means for feeding out the sheets on the sheet stacking means, and the feeding means applies the sheets to the sheet. Support means for supporting the feeding means and a supporting means connected to the supporting means so that the feeding means can move from a contacting feeding position to a standby position separated from the sheet by a predetermined amount, and the feeding means is moved via the supporting means. And driving means for controlling the operating speed of the driving means.

Further, in the sheet feeding apparatus of the present invention, the drive means is such that the drive source for outputting the turning force and the rotation support lever engaged with the support means are connected by the power transmission means. It has a feature.

Further, in the sheet feeding apparatus of the present invention, the control means makes the moving speed of the feeding means from the standby position to the feeding position slower than the moving speed from the feeding position to the waiting position. In addition, the operating speed of the drive means is controlled.

Further, in the sheet feeding apparatus of the present invention, the control means controls the operating speed of the driving means so that the moving speed of the feeding means from the standby position to the feeding position becomes constant. Is characterized by.

Further, in the sheet feeding apparatus of the present invention, the control means is arranged so that the speed immediately before the end of the movement of the feeding means from the standby position to the feeding position is lower than the speed at the time of starting the movement. It is characterized in that the operating speed of the drive means is controlled.

Further, in the sheet feeding apparatus of the present invention, the control means controls the operating speed of the driving means so that the moving speed of the feeding means from the feeding position to the standby position becomes constant. Is characterized by.

Further, in the sheet feeding apparatus of the present invention, the control means is arranged such that the speed immediately before the end of the movement of the feeding means from the feeding position to the standby position is slower than the speed at the start of movement. It is characterized in that the operating speed of the drive means is controlled.

Further, the image forming apparatus of the present invention is provided with any one of the above-mentioned sheet feeding device and an image forming means for forming an image on a sheet fed from the sheet feeding device. I am trying.

Furthermore, the image forming apparatus of the present invention comprises any one of the above-mentioned sheet feeding device and a discharging means for discharging the sheet fed from the sheet feeding device onto the discharged sheet stacking means. It is characterized by that.

(Operation) According to the structure of the present invention as described above, the supporting means for supporting the feeding means is operated by the driving means whose speed is controlled by the control means, and the feeding means is moved to the feeding position. And between the standby position. Since the drive means is driven and controlled by the control means, there is no variation in the timing of switching the position between the standby position and the feeding position. Therefore, the sheets are fed with a small sheet interval during continuous sheet feeding even during high-speed sheet feeding.

Further, according to the configuration of the present invention, when the feeding means is moved from the standby position to the feeding position during high-speed continuous sheet feeding, the moving speed of the feeding means is controlled by the control means to feed the sheet. The impact when the feeding means comes into contact with the sheet is mitigated, the bounce of the feeding means is suppressed, and the sheet is fed at high speed at short intervals.

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. <First Embodiment> FIG. 1 is a perspective view of a main portion of a sheet feeding device K according to a first embodiment of the present invention.

In FIG. 1, a pickup roller 1 for sending out the sheets 11 stacked on the sheet stacking means 21 is rotatably attached to an arm (supporting means) 2 via a shaft 1a. The arm 2 is rotatably attached to a shaft 3 pivotally supported by a bearing (not shown) on the apparatus body side.

The pickup roller 1 has a shaft 1a.
1b fixed to the shaft and 3a fixed to the shaft 3
The drive motor 6 via the drive belt 4 wound around the drive belt 5 and the drive belt 5 wound around the pulley 3a fixed on the shaft 3 and the pulley 6b fixed on the output shaft 6a of the drive motor 6. And is rotated by the drive motor 6.

The rotation support lever 7 is connected to the stepping motor 10 via a power transmission device 22 and constitutes a driving means together with the power transmission device 22 and the stepping motor 10, and the arm 2 is driven by the turning force of the stepping motor 10. Is designed to rotate. A base portion 7a of the rotation support lever 7 is attached to a shaft 8 pivotally supported by a bearing (not shown) of the apparatus body so as to be integrally rotatable. The tip portion 7b of the rotation support lever 7 which is bent in a substantially L shape supports the lower side of the arm 2, and by pushing up the A portion of the arm 2, the arm 2 is moved along the axis 3. It is rotated in the direction a as a rotation axis. As a result, the pickup roller 1 moves to the standby position, which is separated from the uppermost surface (feeding position) of the sheet 11 by a predetermined amount.

Further, when the stepping motor 10 rotates in the opposite direction to the above case, the rotation support lever 7 is rotated in the direction B via the power transmission device 22. At this time, the arm 2 rotates in the direction of arrow B according to the rotation support lever 7 by its own weight, and moves to a position (feeding position) where the pickup roller 1 contacts the uppermost surface of the sheet 11. In this way, the pickup roller 1 moves between the feeding position and the standby position.

The power transmission device 22 is used for the motor shaft 1
A pulley 10b fixed to the shaft 8a, a pulley 8a fixed to the shaft 8, a drive belt 9 wound around the pulleys 10a and 8a, and a shaft 8 linked to a rotation support lever 7.
It consists of.

The stepping motor 10 and the drive motor 6 are connected to a CPU 20 as a control means, and are operated based on a control signal from the CPU 20.

When an operation start signal is output from the CPU 20 to the drive motor 6 when the pickup roller 1 is in the feeding position, the rotational force of the drive motor 6 is transmitted through the drive belts 5, 4 and the like. 1, the pickup roller 1 rotates in the direction of the arrow in the figure to feed the uppermost sheet 11. The sheet 11 sent out by the pickup roller 1 enters a nip portion (not shown) between the conveyance roller and the separation roller (or separation belt), separated by the rollers one by one, and further conveyed to the downstream side. (See, for example, FIG. 6).

According to the present embodiment configured as described above, the rotation support lever 7 is driven (pickup roller 1
The vertical movement of the pickup roller 1 is performed by the stepping motor 10 controlled by the CPU 20, so that the time variation of the switching between the standby position and the feeding position of the pickup roller 1 and the variation of the vertical movement speed of the pickup roller 1 are
Compared with the conventional example in which drive control is performed using solenoids, the number of sheets is significantly reduced (variation becomes almost zero), and the sheet interval during high-speed continuous feeding can be set small.

Further, instead of the stepping motor 10, D
Even when the C motor is used, the same effect as the above case using the stepping motor 10 can be obtained. However, in this case, it is necessary to provide a rotary encoder on the motor shaft of the DC motor, detect the rotation speed of the rotary encoder by a photosensor or the like, and control the rotation speed of the DC motor with a current value.

FIG. 2 shows a control diagram of the pickup roller 1.

The horizontal axis of FIG. 2 shows the elapsed time, and the vertical axis shows the position of the pickup roller 1. Time A shown in the figure is the time when the pickup roller 1 is moving from the paper feed position to the standby position, time B is the time when the pickup roller 1 is moving from the standby position to the paper feed position, and time C is The time from the start of feeding the pick-up roller 1 to the start of feeding the next paper, time D is the time when the bouncing of the pick-up roller 1 is stopped, and time E is the paper feed time of the pick-up roller 1.

By setting the time B to be longer than the time A, it is possible to make the falling speed of the pickup roller 1 the slowest within the time C, and the impact when the pickup roller 1 contacts the sheet 11. Since the bounce when the pickup roller 1 collides with the sheet 11 is controlled, the time D is shortened, and the speed of sheet feeding can be further improved.

That is, the speed at which the pickup roller 1 moves from the standby position to the standby position is higher than the speed at which the pickup roller 1 moves from the standby position to the standby position.
The slower control makes it possible to feed the sheet at a higher speed.

Further, as shown in FIG. 2, by moving the pickup roller 1 at a constant moving speed, the impact when the pickup roller 1 comes into contact with the sheet 11 can be reduced as compared with the conventional example. That is, in the conventional example, in contrast to the present embodiment as described above, the operation of the pickup roller is performed by a solenoid, and the pickup roller falls onto the sheet surface by gravity. Since the speed of the pickup roller becomes faster, the impact when the pickup roller collides with the sheet is larger than that in this embodiment.

Further, according to the present embodiment, since the pickup roller 1 is moved from the feeding position to the standby position at a constant speed, noise is not generated when the pickup roller 1 is stopped at the standby position. It can be suppressed more than the conventional example, and the operation noise of the device can be suppressed. That is, in the conventional example, the pickup roller is pulled up from the sheet surface by the solenoid (moved from the feeding position to the standby position), and the magnetic force of the solenoid gradually becomes stronger as the pickup roller rises. Since the speed becomes faster as it approaches the stop position (standby position), the impact when the pickup roller is stopped is larger than that of the present invention. <Second Embodiment> FIG. 3 is a control diagram of a pickup roller according to a second embodiment of the present invention.

In FIG. 3, the alternate long and short dash line indicates the first
7 illustrates a control state of the pickup roller described in the embodiment. As shown in FIG. 3, in the present embodiment, the moving speed of the pickup roller 1 from the standby position to the sheet feeding position is fast from the standby position to point F and slow from the point F to the feeding position. The speed is controlled by the CPU 20.

As a result, in the present embodiment, the impact when the pickup roller 1 contacts the sheet 11 can be reduced and the bounding time D of the pickup roller 1 can be shortened, so that the sheet feeding interval C'can be set short. Like Therefore, according to the present embodiment, the sheet feeding can be further speeded up. <Third Embodiment> FIG. 4 is a control diagram of a pickup roller according to a third embodiment of the present invention.

In FIG. 4, the alternate long and short dash line indicates the first
7 illustrates a control state of the pickup roller described in the embodiment. As shown in FIG. 4, in the present embodiment, the moving speed of the pickup roller 1 from the standby position to the paper feeding position is fast from the standby position to the point G, and from the point G to the feeding position is the first speed. The speed is controlled by the CPU 20 so that the speed is the same as that of the embodiment (FIG. 2).

As a result, in this embodiment, the moving time (falling time) B of the pickup roller 1 from the standby position to the feeding position can be shortened, and the sheet feeding interval C'can be set short. Therefore, according to the present embodiment, it is possible to further speed up sheet feeding. <Fourth Embodiment> FIG. 5 is a control diagram of a pickup roller according to a fourth embodiment of the present invention.

In FIG. 5, the alternate long and short dash line indicates the first
7 illustrates a control state of the pickup roller described in the embodiment. As shown in FIG. 5, in the present embodiment, the moving speed of the pickup roller 1 from the sheet feeding position to the standby position is fast from the feeding position to the point H and slow from the point H to the standby position. The speed is controlled by the CPU 20.

As a result, in the present embodiment, the pickup roller 1 can be smoothly stopped at the standby position, and the noise generated when the pickup roller 1 is stopped can be further reduced. <Image Forming Apparatus> An image forming apparatus using the sheet feeding apparatus K according to the embodiment of the present invention will be described below with reference to the drawings.

FIG. 7 is a schematic configuration diagram of an image forming apparatus 100 using the sheet feeding device K of the present invention. In this figure, the sheet (image forming sheet) fed from the sheet feeding device K is conveyed to the fixing means 103 by the conveying means 102 after the image is formed by the image forming means 101, and is fixed by the fixing means 103. The image is fixed, and then discharged by the discharging unit 104 to the discharged sheet stacking unit 105.

Further, the sheet (original) sent from the sheet feeding device K as a document feeding device is conveyed onto the platen glass 112, and image information is read by the optical system 106 on the platen glass 112, and then the image is read. After being carried out from the platen glass 112 by the carrying means 113, it is discharged onto the tray 110 as a discharged sheet stacking means by the discharging means 111a or the discharging means 111b.

The image forming apparatus 100 according to the present embodiment as described above is provided with the sheet feeding device K capable of high-speed feeding and quiet in operation sound, and therefore, the image forming speed can be increased. Therefore, the image forming work can be suppressed.

[0048]

As described above, in the sheet feeding apparatus of the present invention, the supporting means for supporting the feeding means is connected to the driving means, and the driving means is speed-controlled by the control means. Therefore, there is no variation in the timing of switching the position between the standby position and the feeding position by the driving means, and it is possible to reduce the sheet interval during high-speed continuous sheet feeding, thereby further speeding up sheet feeding. You can

Further, in the sheet feeding apparatus of the present invention, when the feeding means is moved from the standby position to the feeding position during high speed continuous sheet feeding, the moving speed of the feeding means is controlled by the control means, Since the impact when the feeding means comes into contact with the sheet can be alleviated and the bouncing of the feeding means can be suppressed, the sheet can be fed at a high speed with a short interval, which is combined with the effect of the present invention. Thus, it is possible to more effectively and speedily feed the sheet.

Further, since the image forming apparatus of the present invention is provided with the sheet feeding device capable of feeding the sheet at high speed as described above, the time for the image forming operation can be shortened.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main portion of a sheet feeding device according to a first embodiment of the present invention.

FIG. 2 is a control diagram of the pickup roller.

FIG. 3 is a control diagram of a pickup roller according to the second embodiment of the present invention.

FIG. 4 is a control diagram of a pickup roller showing a third embodiment of the present invention.

FIG. 5 is a control diagram of a pickup roller showing a fourth embodiment of the present invention.

FIG. 6 is a side cross-sectional view of a main part of a conventional sheet feeding device.

FIG. 7 is a schematic configuration diagram of an image forming apparatus.

[Explanation of symbols]

1 Pickup Roller (Feeding Means) 2 Arm (Supporting Means) 7 Rotation Supporting Lever (Drive Means) 10 Stepping Motor (Drive Source, Driving Means) 11 Sheet 20 CPU (Control Means) 21 Sheet Loading Means 22 Power Transmission Means 100 Image forming apparatus 101 Image forming means 110 Tray (discharging sheet stacking means) 111a, 111b Discharging means K Sheet feeding apparatus

Claims (9)

[Claims] 1. A sheet stacking unit for stacking sheets, a feeding unit for feeding out the sheets on the sheet stacking unit, and a standby for separating a predetermined amount from the sheet feeding position where the feeding unit contacts the sheet. Support means for supporting the feeding means so as to be movable to a position, drive means connected to the support means and moving the feed means via the support means, and connected to the drive means, A sheet feeding device comprising: a control unit that controls an operating speed of a drive unit. 2. The seat according to claim 1, wherein the drive means connects a drive source that outputs a turning force and a rotation support lever that engages with the support means by a power transmission means. Feeding device. 3. The control means controls the operating speed of the drive means so that the moving speed of the feeding means from the standby position to the feeding position is slower than the moving speed of the feeding means from the feeding position to the standby position. The sheet feeding device according to claim 1, wherein the sheet feeding device is controlled. 4. The control means controls the operating speed of the drive means so that the moving speed of the feeding means from the standby position to the feeding position is constant.
The sheet feeding device as described in the above. 5. The control means controls the operating speed of the drive means so that the speed immediately before the end of the movement of the feeding means from the standby position to the feeding position is slower than the speed at the start of movement. The sheet feeding device according to claim 1. 6. The control means controls the operating speed of the drive means so that the moving speed of the feeding means from the feeding position to the standby position is constant.
The sheet feeding device as described in the above. 7. The control means controls the operating speed of the drive means so that the speed immediately before the end of the movement of the feeding means from the feeding position to the standby position is slower than the speed at the start of movement. The sheet feeding device according to claim 1. 8. The method according to any one of claims 1 to 7.
An image forming apparatus, comprising: the sheet feeding device according to the item 1; and an image forming unit that forms an image on a sheet fed from the sheet feeding device. 9. The method according to any one of claims 1 to 7.
An image forming apparatus, comprising: the sheet feeding device according to the item 1; and a discharging unit configured to discharge the sheet fed from the sheet feeding unit to a discharged sheet stacking unit.