JPH08295427A - Sheet paper feeding device - Google Patents

Abstract

PURPOSE: To reduce impact when an introducing roller is applied to a sheet at the uppermost part, and restrict feed defective or noise by disorder of the sheet by impact. CONSTITUTION: A paper feeding device is composed by providing a drive gear 157 to drive an introducing roller 151 to feed a sheet P placed on a sheet tray 150 from the uppermost part by a stepping motor to be engaged with a sector gear 152-1 formed integrally with an arm 152 for supporting the introducing roller 151 for moving it between a position where it is applied to the sheet P at a sheet feed position (e), and a stand-by position (a) where it will not be applied to the sheet P. Based on a measured distance by a distance measuring sensor 35 disposed above the sheet tray 150, speed is reduced or brake controlled, for example, when it reaches a position (b) before it is applied to the sheet P from the stand-by position (a).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device for feeding stacked sheets cut into a predetermined size to a predetermined position.

[0002]

2. Description of the Related Art Conventionally, according to an image recording apparatus, a sheet-shaped recording sheet is conveyed to a recording position, a recording image is formed on the sheet, and then the sheet is ejected to the outside of the apparatus. For example, a copying apparatus in which an image of an original is directly formed on a recording medium, the image on the recording medium is transferred to a sheet-shaped conveyed sheet, and the sheet after the transfer is discharged to the outside of the apparatus through a fixing step. Etc.

In the above copying apparatus, a document is placed at a predetermined position, that is, an exposure position, and the document image at the exposure position is projected on a photoconductor which is a recording medium. In this case, in order to save the trouble of manually placing the sheet original at the exposure position,
There is a copying apparatus including an automatic document feeder for stacking sheet originals on an original tray and automatically conveying the sheet originals on the original tray to the exposure position.

Among the automatic document feeders described above, when the image exposure of the sheet document at the exposure position is completed, the document is fed from the exposure position and re-transported to the exposure position again to form an image. Some are returned to the loading tray. There is also a recirculating document transport device (Recirculating Document Handler; hereinafter referred to as RDH) that returns the sheet document from the document mounting tray to the exposure position and from the exposure position to the document mounting tray.

There is also a recording (or copying) device for performing not only sheet originals but also double-sided recording (copying) for forming images on both sides of a cut sheet or composite recording for forming images on the same side of a sheet by superimposing. . In the copying machine having the double-sided and synthesizing function, before discharging the paper on which the original image is formed on one surface to the outside of the apparatus, the paper is temporarily discharged and stored in the intermediate tray, and the paper in the intermediate tray is re-described above. The image is conveyed to the image forming position of the copying machine and an image is formed on the opposite surface or the same surface.

Therefore, in order to feed the sheet to a desired position as described above, the sheets stacked on various trays are
A paper feeding device is provided for feeding from this position. That is, it corresponds not only to the feeding of stacked sheet originals in the RDH and to the intermediate tray of the sheet paper but also to the tray on which the sheet feeding device is stacked to feed the sheet of paper stacked for recording an image. And each is provided independently.

As an example of this paper feeding device, as shown in FIGS. 13 and 14, there is provided a take-in roller 107 which can move up and down corresponding to the sheet paper or the sheet original stacked on the loading tray 119. Then, the uppermost sheet is sent out by the take-in roller 107, and is sent between the paper feed roller 105 and the reverse separation roller 110 which are provided to prevent double feeding.

The paper feed roller 105 is fixed to the rotary shaft 101, and is rotationally driven in the direction of sending the sheet to the transport roller 122. A drive gear 113 is fixed to the rotary shaft 101 by a pin 114, and a rotational force from a drive motor (not shown) is transmitted via a clutch and a transmission means. This drive gear 113 is a driven gear 115
A gear 116 fixed to the rotation shaft 112 of the reverse separation roller 110 is meshed with each other, and the separation roller 110 is driven to rotate in the same direction in accordance with the rotation of the paper feed roller 105, thereby feeding the paper. At the contact position with the roller 105, the sheet sent by the take-in roller 107 is rotationally driven in the direction of returning it to the placing tray 119.

Therefore, when the sheets sent out by the take-in roller 107 are double-fed, the uppermost sheet is fed to the conveying roller 122 side by the sheet feeding force of the sheet feeding roller 105. The sheet below the uppermost sheet is fed back by the reverse separation roller 110, and one sheet is fed.

In particular, the reverse separation roller 110 includes a rotary shaft 11
It is attached to No. 2 via a torque limiter 111. Therefore, at the time of double feeding, the lower sheet is fed back in the direction to be fed back through the above-described reverse rotation drive mechanism. However, when there is no sheet or the like, the separation roller 1 follows the rotation of the paper feed roller 105 due to the frictional resistance.
10 is driven to rotate in the same direction at the contact portion,
The torque limiter 111 is provided.

Further, the call-in roller 107 is the paper feed roller 1.
05 is fixed to a shaft 117 rotatably provided between a pair of arms 109 rotatably provided on the rotary shaft 101. A driven gear 108, to which the rotation of the gear 104 fixed to the rotating shaft 101 is transmitted via the intermediate gear 106, is fixed to the shaft 117. Therefore, the intake roller 107 rotates the feed roller 105. Will be driven to rotate. Further, the arm 109 has the rotating shaft 101.
Since it is rotated about the fulcrum, the intake roller 107 can move up and down between the standby position shown by the solid line and the paper feeding position shown by the broken line. In this vertical movement mechanism, a friction plate is interposed between one arm 109 and the gear 104,
The arm 109 is pressed toward the gear 104 by the coil spring 102 provided on the rotating shaft 101, and is rotated in the rotating direction in association with the rotation of the rotating shaft 101.

Therefore, as the paper feed roller 105 is driven to rotate, the reverse separation roller 110 and the intake roller 107 rotate, and at the same time, the arm 109 causes the coil spring 1 to rotate.
At 02, the friction plate 103 is rotated in conjunction with the rotary shaft 101, and the pickup roller 107, which was at the standby position, is lowered to the paper feeding position where it abuts the uppermost stacked sheet. At this time, the invoking roller 107 contacts the uppermost sheet of the arm 109, whereby further rotation is restricted and the arm 109 slips with respect to the rotating shaft 101.

The lowermost sheet of the uppermost sheet comes into contact with the uppermost sheet and is fed in the rotational direction by the lowering of the sheet feeding roller 109, and the leading edge is fed between the sheet feeding roller 105 and the reverse separation roller 110. The reverse separation roller 110 is the paper feed roller 105.
In the state in which the sheet feed roller 105 is in contact with the sheet feed roller 105, the sheet is driven to rotate in accordance with the rotation direction of the sheet feed roller 105, and therefore the leading edge of the fed sheet is fed in the sheet feed direction as it is. However, if two or more sheets are fed in a state of being overlapped (when they are fed multiple times),
The friction resistance between the reverse separation roller 110 and the sheet is larger than the friction resistance between the sheets, and the torque limiter 1
Since the frictional resistance is increased by 11, the reverse separation roller 110 is reversely driven in the direction in which the sheet is sent back to the loading tray 119 side. As a result, the uppermost sheet is sent out to the transport roller 122 side by the paper feed roller 105, and the following sheets are sent back to feed one sheet.

Further, the sheet feeding device shown in FIGS. 15 and 16 does not move the take-in roller up and down in accordance with the rotation of the rotary shaft of the sheet-feeding roller, but lowers by the cam mechanism and the weight of the take-in roller. It is what makes me. 15 and 16, the same reference numerals are given to the same acting parts as those in FIGS. 13 and 14.

Transmission of the rotation between the shaft 117 rotatably provided on the pair of arms 109 and the rotary shaft 101 is performed by the timing belt 106a instead of the gear, and the intermediate gear is omitted.

In this paper feeding device, the feeding roller 10
In order to move 7 up and down, a rotary cam 121 is provided so as to come into contact with the arm 109 on the side opposite to the position where the roller 107 is rotatably held. When the rotary cam 121 rotates and the tip of the rotary cam 121 comes off the arm 109, the rotatably provided arm 109 rotates about the rotary shaft 101 by its own weight due to the load including the intake roller 107, and the intake roller is rotated. 107 is lowered to a position where it comes into contact with the uppermost sheet on which it is placed. In this state, the take-in roller 107 and the reverse separation roller 110 are also rotationally driven according to the rotation of the paper feed roller 105, and only the uppermost sheet is fed as in the case of FIG. When this paper feed is performed, the rotary cam 121 is driven to rotate once and then stopped, so that the arm 109 is lifted as shown in the figure and the take-in roller 107 is separated from the uppermost sheet on which it is stacked.

[0017]

According to the above-mentioned conventional technique, in the paper feeding device, it is necessary to lower the pickup roller to the uppermost sheet to be placed in the paper feeding operation. The lowering operation is completed in the state where the drawing roller is in contact with the upper sheet. At this time, noise is generated due to the impact when abutting. To reduce this shock,
Although it is effective to slow down the lowering operation, FIG.
In the paper feeding device of No. 2, since it is lowered by its own weight, it is impossible to delay its operation.

Further, in the paper feeding apparatus of FIG. 13, the driving of the rotary shaft 101 may be slowed down, but the lowered state is unknown, and in which state the drive speed of the rotary shaft 101 is the drive speed in the paper feeding operation. It is unclear whether to return to.
Therefore, it is also possible to provide a timer corresponding to the operation time for descending in accordance with the distance between the intake roller and the uppermost sheet, and after this timer time, return the rotation speed of the rotating shaft 101 to the speed of the paper feeding operation. is there.

However, if the position of the uppermost sheet is always maintained at a constant height according to the continuous sheet feeding operation, the timer may be constant, but the uppermost sheet position If the (height) decreases with each paper feed, it is an absolute requirement to set the timer setting time to the time to drop to the position where all sheets are exhausted. It takes a long time to support high-speed paper feeding.

Further, the contact sheet is violent due to the impact when the pickup roller is lowered according to the sheet feeding operation, which causes the oblique feeding and the two-sheet feeding. Due to the large impact, not only the uppermost sheet but also the lowermost sheet are driven by the invoking roller, so that the adhesive force between the sent out sheets becomes stronger than the impact, and the sheet may be fed through the sheet feeding roller 105 as it is. is there. Further, the sheet is displaced to the left or right due to the impact, so that the above-mentioned oblique feeding occurs.

In view of the above points, the present invention provides a sheet feeding device that controls the lowering operation of the take-in roller to reduce the impact caused by the contact with the uppermost sheet and to eliminate noise and defective feeding. To aim.

Another object of the present invention is to provide a device which can cope with high speed sheet feeding without prolonging the sheet feeding time.

Another object of the present invention is to eliminate the above-mentioned noise and defective paper feeding by shortening the distance in the lowering operation of the take-in roller.

[0024]

SUMMARY OF THE INVENTION A first sheet feeding device of the present invention is a loading tray on which sheets are stacked, and a vertically movable caller for feeding sheets on the loading tray. A sheet feeding device having a feed roller and a moving mechanism for moving the feed roller between a sheet feed position in contact with a sheet and a standby position separated from the sheet, the sheet feed device being placed on the placement tray. A distance measuring sensor for measuring the distance to the uppermost portion of the sheet is provided, and the moving mechanism is controlled based on the distance measured by the distance measuring sensor, and the call is made at a position before the contact between the feeding roller and the sheet. The lowering speed of the trailing roller is controlled. Particularly, in the control, the driving to the descending position is performed at high speed, and the descending position to the position where the sheet comes into contact with the sheet is driven at low speed, with the descending position at which the contact comes in advance as a boundary.

Further, the second sheet feeding device of the present invention comprises a loading tray on which sheets are stacked, an up-and-down moving roller for feeding sheets on the loading tray, A sheet feeding device having a moving mechanism for moving a pickup roller between a sheet feeding position in which the sheet comes into contact with a sheet and a standby position separated from the sheet, the sheet feeding device extending up to the top of the sheets stacked on the placing tray. A distance measuring sensor for measuring distance is provided,
The moving mechanism is controlled on the basis of the distance measured by the distance measuring sensor, the descent roller is driven down to the position where it comes into contact with the sheet, and the descent roller is moved up to a position where it is separated from the sheet after feeding. At the end of the period, control is performed to stop the raised position between the standby position and the abutting position at a preliminarily lowered position where the seat abuts.

In the second sheet feeding device, when the pickup roller is raised to the lowered position after the sheet is fed and the lowering control of the pickup roller for the next sheet feeding is performed from this position, the sheet is fed previously. Correct the descent distance according to the thickness of the sheet,
Descent control is performed based on the corrected descent distance.

Here, the thickness of the sheet is determined by the difference between the distance measured after the sheet is fed and before the next sheet feeding and the distance measured before the previous sheet feeding, and the thickness is calculated as the thickness. The descent distance from the descent position of the invoking roller is controlled in accordance with the correction.

Further, the first and second sheet feeding devices are provided with means for detecting the fed sheet, and the sheet is fed from the lowered position of the take-in roller according to the detection state of the sheet detecting means. Correct the drive distance until the contact.
That is, the pressure contact force at the time when the intake roller comes into contact with the sheet is controlled according to the detection state of the sheet detection means.

[0029]

According to the first sheet feeding device of the present invention, the distance from the pickup roller to the uppermost sheet is measured by the distance measuring sensor before the sheets stacked on the loading tray are fed. To be measured. Based on the measurement result, when the take-in roller existing at the initial standby position is lowered to the sheet feeding position where it comes into contact with the sheet, speed control for lowering is performed. In particular, based on the measured distance, when the descent is performed, the descent position before the contact roller comes into contact with the sheet is calculated. That is, in driving the invocation roller in accordance with the distance (e) obtained by subtracting the above-mentioned measured distance from the distance before the invocation roller comes into contact with the sheet, the inducing roller is lowered at a high speed and then the above-mentioned distance (e). For, the descent drive is performed at a low speed. As a result, when the invocation roller comes into contact with the sheet, the impact is reduced, and the problem caused thereby can be resolved.

According to the second sheet feeding device of the present invention,
The distance measurement is performed by the distance measuring sensor as described above according to the sheet feeding operation, and the descending distance of the feeding roller is controlled according to the measured distance to bring the sheet into contact with the sheet to feed the sheet. After this paper feeding, the feeding roller is raised to a position before coming into contact with the sheet and stopped without returning to the standby position. This position is, for example, the distance (e) before the contact with the sheet as described above. In the next paper feeding, the descent time can be shortened because the descent control can be performed from the front side.

In the second sheet feeding device, when the next sheet is fed while the sheet feeding roller is in the lowered position before the sheet contact position, the sheet fed last time is fed. The correction control is performed according to the thickness of the. That is,
Since the sheet is not being fed when the take-in roller is raised, the descending distance is corrected according to the thickness of the sheet. As a result, the contact control of the intake roller to the sheet can be reliably performed. In this case, the thickness (t) of the fed sheet can be obtained from the difference between the distance measured before the previous feeding and the distance measured before the current feeding. Therefore, by processing the thickness (t) as a correction value for the descent control of the calling roller existing in the descent position, the descent control of the calling roller can be performed according to the thickness of the previously fed sheet. . As a result, the contact relationship between the sheet feeding roller and the sheet can be ensured, and the sheet feeding operation can be stabilized.

Further, in the first and second sheet feeding devices, it is determined whether or not the sheet feeding is normally performed by the sheet detecting means for detecting the sheet feeding state in the sheet feeding operation. Here, in the case of the sheet feeding failure, that is, when the sheet is not fed correctly, in the next feeding operation,
When controlling the lowering of the intake roller according to the measurement distance, the predetermined distance (e) is lowered from the lowering position,
A predetermined distance is added to this distance to perform descent control. As a result, the pressure contact force with the sheet when the pickup roller reaches the sheet feeding position can be increased. Therefore, the sheet feeding force is increased, the preceding sheet feeding failure can be eliminated, and the sheet feeding operation can be reliably performed.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a sheet discharging device according to the present invention will be described below with reference to the drawings. Further, in the following embodiments, a copying apparatus will be described as an example of the recording apparatus, but the present invention is not limited to such an apparatus. In other words, the present invention can be applied to all apparatuses that stack cut sheets of paper or originals on a tray or a paper feed cassette and feed the topmost stacked paper.

FIG. 1 is a block diagram showing a control circuit of a copying apparatus according to the present invention, FIG. 2 is a schematic sectional view showing an example of a copying apparatus to which the sheet feeding apparatus of the present invention is applied, and FIG. FIG. 4 is a sectional view showing an example of a paper device, and FIG. 4 is a perspective view thereof.

In FIG. 2, the copying machine is a copying machine main body 1
And a document processing unit, that is, an RDH 30 which is a document feeding device for sequentially transporting the document to the document exposure position and returning it to the original position after processing.

An optical system 2 for exposing an original image for image formation is arranged on the upper part of the copying apparatus main body 1. The optical system 2 includes a copy lamp 3 including a halogen lamp, a plurality of mirrors 4 to 7, a zoom lens 8 and the like.
And have.

Below the optical system 2, a photosensitive member 9 having a photoconductive layer on the surface of a drum-shaped recording medium is rotatably arranged. Various devices for forming an image are arranged around the photoconductor 9.
For example, a charger 10, a developing unit 11, a transfer unit 12, a cleaning unit 13, a static eliminator 14 and the like are arranged.

In forming an image, first, the surface of the photoreceptor 9 is uniformly charged to a predetermined potential by the charger 10, and then the original is irradiated by the optical system 2 to reflect the reflected light to the mirror and the lens. The image is projected on the surface of the photoconductor 9 via. As a result, an electrostatic latent image corresponding to the image of the original is formed on the photoconductor 9, and toner is attached to the developing unit 11 in order to visualize the latent image to form a toner image. As the toner image, a sheet of paper is fed from a paper feeding unit selected from a plurality of paper feeding units 15, and is transferred through a registration roller 16 that feeds the paper in synchronization with the rotation of the photoconductor 9. Is electrostatically transferred to the transfer position where is placed on the sheet paper which is appropriately fed by the operation of the transfer device 12.

After that, the sheet of paper is peeled off from the photoconductor 9 and sent to the fixing section 18 through the suction / conveyance means 17. The fixing section 18 is composed of, for example, a heat roller whose upper side in contact with the toner image is heated to a constant temperature by at least a heat source, and a pressure roller which presses the heat roller with an appropriate pressure. , The toner image on the sheet of paper is heated and fixed. The fixed sheet of paper on which an image has been formed is discharged onto a sorter 20 for aligning the sheets of paper connected to the discharge port 19 of the copying apparatus main body 1 in page order, and also forms a sheet of image. It is sent to a transport means 22 for transporting to an intermediate tray 21 provided at the lower part of the copying apparatus main body 1 for forming an image again on the opposite surface or the same surface. The sheet paper carried by the carrying means 22 is carried out to the intermediate tray 21 via the switchback carrying section 23, or as it is via the carrying section 24. That is, by passing through the switchback transport unit 23, the feeding direction of the leading edge and the trailing edge of the sheet of paper is reversed and the front and back sides are reversed, and the intermediate tray 21 is transported through the transport unit 24.
It is carried out to, but if it goes through the transport unit 24 as it is,
The sheet is conveyed to the intermediate tray 21 without being turned upside down.

On the intermediate tray 21, a placing table 25 for placing sheets, a pickup roller 26 for feeding the sheet sheets on the placing table 25, and a sheet feeding for feeding the fed sheet sheets. A sheet feeding device including the means 27 is provided.

The sheet papers stored in the intermediate tray 21 are sequentially fed one by one by the action of the take-in roller 26, for example, from the uppermost one, and the above-mentioned image forming unit is fed through the paper feeding means 27 and various conveying rollers. Registration roller 1
A transport unit 28 for feeding the sheet to the sheet feeding device 6 is provided behind the sheet feeding unit 27 (downstream side in the transport direction).

On the other hand, the optical system 2 transfers the image of the original to the photoconductor 9
In addition to the RDH 30, the original placed on the original table 29 made of a transparent glass plate is optically scanned in order to project the image onto the original. Therefore, a first mirror base (not shown) composed of the lamp 3 and the mirror 4 and a second mirror base (not shown) composed of the mirrors 4 and 5 are moved in the arrow A direction,
The document on the document table 29 is optically scanned and sequentially projected onto the rotating photoconductor 9.

In addition to the image exposure on the document table 29, the optical system 2 also positions the first exposure section 31 and the second exposure section 32 for image exposure in response to the document being conveyed by the RDH 30 described above. Can be moved to. That is, RDH3
The first exposure unit 31 and the second exposure unit 32, which are made of transparent plates, are arranged side by side in sequence while the sheet document is being conveyed at 0. The optical system 2 is selectively fixed at positions corresponding to the first exposure section 31 and the second exposure section 32. Therefore, by fixing the first mirror base and the second mirror base at the positions shown in the figure, the image of the document conveyed on the first exposure unit 31 is projected onto the surface of the photoconductor 9. Further, by moving the first mirror base and the second mirror base of the optical system 2 to the second exposure unit 32 and fixing them in that position, the image on the opposite surface of the sheet original conveyed to the second exposure unit 37 is displayed. It can be projected on the photoconductor 9.

The paper feeding device according to the present invention is a paper feeding device 1 for feeding a sheet of paper to the position of the registration roller 16.
5, a sheet feeding device for feeding the copied sheet sheets accommodated in the intermediate tray 21, and a sheet feeding device for feeding the sheet originals in the RDH from the position where the sheet documents are stacked to the conveying path. Details are shown in FIGS. 3 and 4. The structure of the sheet feeding device 15 will be described below.

The sheet feeding device 15 is provided with a pickup roller 151 movably up and down corresponding to the sheets P stacked or accommodated in the placing tray 150 or the sheet feeding cassette. The take-in roller 151 is held by an arm 152 whose rotation shaft 151-1 is rotatably supported, and the arm 152 is provided for sending out the sheet paper sent out by the take-in roller 151 to the conveying roller 33. Paper feed roller 1
The rotary shaft 153-1 of 53 is rotatably provided.

The paper feed roller 153 and the call-in roller 151
The transmission mechanism of the rotation with the gears 153-2 and 151-2 fixed to the respective rotating shafts 153-1 and 151-1.
The timing belt 154 is provided so as to bridge the above. Further, a reverse separation roller 155 is provided in order to prevent the double feeding of the sheet paper that has been fed facing the paper feed roller 153. Although not shown, the rotation transmission mechanism between the paper feed roller 153 and the reverse separation roller 155 includes, for example, a drive gear fixed to the rotary shaft 153-1 and a driven gear fixed to the rotary shaft 155-1. An intermediate gear is provided between them. Therefore, the reverse separation roller 155 is rotationally driven in the same direction as the paper feed roller 153, and the moving direction is opposite at the contact position with the paper feed roller 153.

The reverse separation roller 155 is attached to the rotary shaft 155-1 via a torque limiter 156 so that it is driven to rotate when it comes into contact with the paper feed roller 153. It is configured to be rotationally driven in a direction in which the lower sheet is fed back. This torque limiter has a well-known structure and is similar to that described with reference to FIG.

On the other hand, the paper feeding device 15 includes
In order to vertically move 51, an up / down moving mechanism for rotating arm 152 is provided. This moving mechanism
The arm 152 is composed of a fan-shaped gear portion 152-1 formed on the side opposite to the support position of the intake roller 151, and a drive gear 157 meshing with the gear portion 152-1. The drive gear 157 has a shaft 157-1 to which a rotational force from a drive source such as a stepping motor (not shown) is transmitted. Therefore, when the drive gear 157 is rotationally driven in the clockwise direction in the figure, the arm 152 is rotated in the counterclockwise direction, and the intake roller 151 is lifted in a direction in which it is separated from the uppermost sheet P on the loading tray 150. Let Further, in the clockwise rotation drive, the intake roller can be lowered in the direction in which it comes into contact with the uppermost sheet P.

Further, in the present invention, the loading tray 1
A distance measuring sensor 35 for measuring the distance to the uppermost portion of the sheet paper P placed on the sheet 50 is arranged on the copying machine main body side so as to face the sheet paper P placed thereon. Therefore, the distance measuring sensor 35 detects, that is, measures the distance from the sensor position to the uppermost portion of the sheet. According to the present invention, the rotation drive control of the stepping motor is performed according to the measured distance in order to control the rotation speed of the drive gear 157. As a result, the rotation speed of the arm 152 is controlled, the descending speed is controlled from the standby position (position shown by the solid line in FIG. 3) a of the intake roller 151, and the descending position immediately before contact with the uppermost sheet (see FIG. By lowering the descent speed after the position (broken line position 3 in FIG. 3) b to a low speed, the impact at the paper feeding position (the position indicated by the one-dot broken line in FIG. 3) in contact with the uppermost sheet is reduced. Further, as shown in FIG. 3, the raising position of the invoking roller can be controlled to be lowered to the lowering position b before coming into contact with the uppermost sheet without returning to the standby position.
The paper feed start time can be shortened.

Next, the control system in the present invention will be described.

As shown in FIG. 1, the control system is a microcomputer 40 including a master CPU as control means.
And a slave CPU 41 that controls the optical system 2 and the like. The master CPU 40 receives signals from various keys and sensors according to a program stored in advance in the ROM 42, and when the document on the document table 35 is optically scanned, the slave CPU 41 uses the first and second mirror bases. A signal for instructing the movement start in the A direction and a signal for returning the first and second mirror bases that have finished the movement in the A direction to the home position or the like are output.

The slave CPU 41 is the master C
According to a command from the PU 40, the first and second mirror bases are moved to the position of the first exposure unit 31 or 32 shown in FIG. 2 and controlled so as to be fixed at the position. To that end,
The slave CPU 41 inputs the signal indicating the rotational position from the rotary encoder 48 directly connected to the motor 47 for moving the mirror base,
A control signal is output to a driver 49 that controls the rotation of the motor 47.

The master CPU 40 controls lighting of a copy lamp, which is a process unit of the image forming apparatus of the copying apparatus, control of supply voltage, and driving control of a charging device, a developing device, a transfer device, and a static eliminator. . Moreover, sheet feeding control is performed in the sheet feeding device 15 and the like according to the present invention.
Note that, on the RDH side, sheet master sheet feeding control is similarly performed on the master CPU 41 side.

In order to perform the above paper feed control, the master CP
U40 is a take-in roller 15 that constitutes the above-described sheet feeding device.
The control circuit 50 for rotationally controlling the stepping motor 38 for rotating the arm 152 of the same, the circuit 51 for controlling the rotation of the drive motor 39 for rotationally driving the paper feed roller 153, and the like at the same time as the timing control. Output a signal for control.

Further, the master CPU 40 is connected to a display control circuit 53 for driving and controlling a display device 52 for displaying the contents of the copy state and other necessary information as required. The display device 52 is provided on the operation panel similarly to the operation key 54 for inputting necessary data such as copying conditions of the copying device. This operation key 54 is also the master CP
It is connected to U and the content of key operation is grasped by the CPU 40. Then, tray detection means 55 for detecting the drawer and mounting of a mounting tray or the like on which the sheet paper according to the present invention is mounted, and a plurality of sheets arranged in the paper transport path for detecting the transport state of the paper. Detection sensor 56
The detection signal and the like are also input to the CPU 40.

On the other hand, the master CPU 40 receives a signal related to the measurement from the distance measuring sensor 35 according to the present invention, and drives and controls the stepping motor control circuit 50 and the like for controlling the driving of the paper feeding device 15 described above. Is outputting the signal. As a result, the stepping motor control circuit 5
0 controls the rotation of the stepping motor according to the instructed speed.

The distance measuring sensor 35 has a light emitting element 35-1 for measuring the distance. Therefore master CP
The U 40 drives the light emitting element 35-1 at a predetermined timing via the driver 36 to measure the distance of the distance measuring sensor 35, and the light receiving element 35- of the distance measuring sensor 35 at this time is driven.
The signal output according to the state of being received by the light receiving device 2 is received via the signal processing circuit 37, and the distance to the leading edge of the discharged document is measured (calculated) based on the received signal. In accordance with this distance measurement, the master CPU 40 sets the rotation speed of the stepping motor 38, and also sets the rotation speed for the reverse rotation drive of the stepping motor 38 after paper feeding.

The RDH is also provided on the slave CPU 41 side.
In the case of feeding the sheet document in, the driver for driving the light emitting element and the processing circuit for processing the signal from the light receiving element similar to the distance measuring sensor 35 are connected. Also in the slave CPU 41, the sheet feeding control according to the measurement distance from the distance measuring sensor 35 is performed by the master CPU.
Run independently of 40.

A specific example of distance measurement will be described in detail with respect to the distance measurement sensor for measuring the distance from the distance measurement sensor 35 according to the present invention to the uppermost position of the stacked sheets. This distance measuring sensor is described in "Sensor Technology", October 1992
Monthly Volume 12, No. The sensor described in "8-bit precision distance measuring sensor" on pages 24 to 27 of No. 11 is used. This sensor is, for example, a PSD (Position Sensit).
This is called "ive Deector", in which light from a light emitting element is applied to an object to be measured, and the distance is measured by the position where the reflected light from the object to be measured is incident on the light receiving sensor.

A brief description of this sensor is P
As shown in FIG. 5, this is a type of IN photodiode, which is composed of a p ⁻ layer on the front surface of the silicon chip, an n ⁺ layer on the back surface, and an i layer in the middle, and each of the front and back layers is shown in the figure. This is a configuration in which electrodes A, B and C as shown are provided. An equivalent circuit of the PSD sensor having the structure shown in FIG. 5 is shown in FIG.

In FIG. 6, by supplying the bias voltage VB to the terminal of the electrode C, the resistances R1 and R2 change at the position (spot position) of the light incident on the surface. For example, if light is incident on the midpoint (point d) between the electrodes A and B,
Although R1: R2 = 1: 1, the ratio of R1: R2 changes in proportion to the position of the incident light if the incident light deviates to one of the A and B electrodes. Now, assuming that the incident position of light is shifted to the B electrode side by x with respect to the center point d, and the length of the light receiving surface of the sensor (distance between A and B electrodes) is D, R1 + R2 = R0, R1 = R0 / 2 (1 + 2x / D) and R2 = R0 / 2 (1-2x / D).

Therefore, the current I extracted from the electrodes A and B in FIG. 6 is utilized by utilizing the above resistance change at the light incident position (spot position) on the light receiving surface of the PSD sensor.
1 and I2, and the current ratio I1 / I at this time
2 is proportional to the distance from the electrode B, for example. At this time, PS
Depending on the amount of light incident on the D sensor, the currents I1 and I2 are
Although the absolute value of changes, I
Since it is proportional to 1 / I2, there is no influence of the light amount itself. Therefore, in the relation of the current ratio I1 / I2, the position of the incident light on the light receiving surface on the PSD sensor can be specified, and thus accurate distance detection can be performed. In particular, when the current ratio becomes large, the incident light approaches the electrode A side of the PSD sensor, and conversely, when the current ratio becomes smaller, the electrode B side is irradiated with the incident light.

For example, as shown in FIG. 7, the light from the light emitting element (infrared LED) 35-1 is radiated to the uppermost part of the stacked sheet paper P in the present invention, which is the object to be measured, and its reflected light. The distance sensor 35 receives the light through the light receiving lens. The position x1 of the light receiving point (spot) at this time is obtained by x1 = A · f / D1 in the relationship shown in the figure. In the above equation, A is the center distance between the light projecting lens and the light receiving lens, D1 is the distance from the light projecting lens to the object to be measured, and f is the focal length of the light receiving lens. Therefore, the position x1 of the light receiving spot on the light receiving surface of the distance measuring sensor 35 becomes smaller and the position moves to the position x2 as the distance to the measured object increases. On the contrary, when the position x1 of the light receiving spot becomes large, the distance to the object to be measured becomes short.

Therefore, since the point x on the light receiving surface of the distance measuring sensor 35 can be specified by the current ratio I1 / I2 obtained from the electrodes A and B as described above, the light emitting element 35-1 can be easily obtained according to the above equation. To the measured object, that is, the distance to the distance measuring sensor 35 can be measured.

Therefore, in the present invention, as shown in FIG. 1, the currents I1 and I2 obtained from the PSD sensor, which is the distance measuring sensor 35, are converted into voltages V1 and V2 by the signal processing circuit 37, and the voltage of the master CPU 40 is changed. Input via the analog port input section. Here, the signal processing circuit 37
The conversion processing is performed as a voltage value equivalent to or equal to the obtained currents I1 and I2. Master CPU 40
Calculates a value corresponding to I1 / I2 based on this voltage value to obtain the spot position (x) of the distance measuring sensor 35,
Thus, the distance L (D1) to the uppermost position of the sheet P is calculated from the above formula for obtaining x.

According to the present invention, based on the output from the distance measuring sensor 35, in the present invention, the vertical movement mechanism of the invoking roller 151 is controlled to control its movement and lowering speed, and at the same time, it is necessary. The rising position of the intake roller 151 is controlled accordingly.

FIG. 8 shows the control of the sheet feeding device 15 according to the present invention.
In particular, the vertical movement control of the call-in roller 151 and the like are controlled by the master CP based on the distance measured by the distance measuring sensor 35.
It is a flowchart which U40 controls. Each embodiment of control will be described below with reference to FIG.

(Embodiment 1) Initialization (step S1) is performed by turning on the power of the copying apparatus. This is the initial use state of the copying machine, for example, the number of copies is set to "1", the copy magnification is set to "100%" standard image density, and the mirrors and lenses in the optical system are moved to the standby position (home position). And sensor check for jam detection. Then, an operation such as warming up of the copying machine is started. In the middle of this process, the state before the paper feeding operation in the paper feeding device, particularly the height to the top of the sheet paper stacked on the loading tray according to the present invention is measured by the distance measuring sensor 35 (S2). To do. In this distance measurement, a drive signal is output from the CPU 40 via the driver 36 in order to drive the light emitting element 35-1 of the distance measuring sensor 35 to emit light.

At this time, the area of the sheet feeding device 15 is in a stationary state at the initial stage, and the distance to the uppermost portion of the sheet paper P placed on the placing tray 150 can be measured in a stable state. . The distance (L) measured by the distance measuring sensor 35, that is, the voltages V1 and V2 input to the CPU 40 via the signal processing circuit 37 are calculated from the sensor based on the above-described calculation formula in accordance with the voltage ratio from the sensor to the top of the seat. The distance L to is calculated. The calculated distance L is stored in a desired area of the RAM 44, which is a storage unit (S3).

Then, the distance L obtained by the calculation
In order to prevent the noise and the defective feeding from being generated by colliding with the sheet when the feeding roller 151 is brought into contact with the uppermost portion of the sheet to feed the sheet, the stepping motor 38 is driven so as to come into contact with the sheet gently. Arithmetic processing for control (S
4) is performed.

As the arithmetic processing, the call-in roller 151 is used.
It is the timing to slow down the descending speed when the sheet comes into contact with the uppermost sheet. That is, in FIG. 3, the descending speed is driven at high speed from the standby position a indicated by the solid line to the descending position b before coming in contact with the uppermost sheet P, and the sheet P is driven.
With the brake timing of the stepping motor 38, the rotational speed is driven at a low speed from the descending position b just before the contact with the sheet feeding position c. The lowering position b to the paper feeding position c are set as a predetermined distance (e).

Therefore, the call-in roller 151 is normally present at the standby position a, and the distance to the distance measuring sensor 35 is constant (d). If this distance d is subtracted from the distance L measured by the distance measuring sensor 35 (Ld), the distance from the top of the sheet to the intake roller 151 can be obtained. At this time, as the timing to slow down the descent speed, the distance (L-d) obtained from the top of the seat at a preset distance (e) is determined.
A distance (L-d-e) is calculated by further subtracting the distance e. For this calculated distance, the descending speed of the ingesting roller 151 is increased, the distance is driven, and then the injecting roller 151 is driven at a low speed. The remaining distance e for pressing the uppermost sheet is lowered.

In order to lower the intake roller 151, the fan gear 152-1 is rotated by the drive gear 157 in this embodiment, as shown in FIG. 3, whereby the intake roller 151 is moved from the standby position a. Paper feed position c that abuts sheet P
Can be lowered to. At this time, as shown in FIG. 3, when the call-in roller 151 is in a standby state (position shown by a solid line), the gear 135 rotated via the stepping motor 38 is rotated counterclockwise, so that the call-in roller 151 is rotated. Gradually descend. Therefore, it is possible to control the descending distance of the intake roller 151 by the number of steps of the stepping motor 38.

For example, the paper feed roller 153 and the call-in roller 1
Assuming that the straight line between 51 and the rotation axis center is in the horizontal state (state at the standby position a), the radius of the pitch circle of the gear 157 is r
1, the radius of the pitch circle of the fan gear 152-1 is r2 (r1
<R2), r3 is the distance between the centers of the rotating shafts of the paper feed roller 153 and the call-in roller 151, and the radius of the call-in roller 151 is r.
Set to 4. Then, it is assumed that the distance measuring sensors 35 are arranged at a distance d to the position facing the sheet P surface of the intake roller 151 as described above. Further, the rotation angle of one step (one pulse) by the stepping motor is, for example, π / 36 radians (5 °) to simplify the explanation.

The distance Lo between the uppermost sheet P and the lower portion of the intake roller 151 facing the uppermost sheet is (Ld) as described above with respect to the distance L measured by the distance measuring sensor 35. Desired. In addition, when the stepping motor is driven by one step (one pulse), the angle α at which the intake roller 151 side rotates is (π / 36) · (r1
/ R2), and the descent distance at that time is r3 · si
It can be obtained by nα.

Therefore, as the step number (pulse number) p of the stepping motor for lowering the distance Lo, Lo = r3.sin (p.α + θ) Here, θ is the angle of the waiting roller 151 in the standby state, and the angle is “0” in the horizontal state as described above, and will be described below in the state of 0. If the position is lower than the horizontal state, the angle will be negative. Therefore, if α · P is sufficiently small in the vicinity of the horizontal state of the intake roller 151, it can be approximated as sin α · p≈α · p (circular motion is regarded as linear motion). Therefore Lo = r
3 · α · p, and the number p of steps is p = (Lo / r3) · α. However, α is (π / 36) · (r1 / r2).

In the above equation 2, the rotation step number p of the stepping motor 38 for lowering to Lo is obtained, and when the stepping motor 38 is rotationally driven, as described above, it is always close to the top sheet. The distance e is set in advance, and the distance to be lowered to this position is obtained by Lo-e, and the corresponding step number p1 can be obtained from the above equation. This step number p1
2), the stepping motor 38 is driven at high speed, the step number p2 (p-p1) corresponding to the remaining distance e is driven at low speed, and the driving of the stepping motor 38 is stopped after the step number p. As a result, the collision between the uppermost sheet and the intake roller 151 can be reduced, and it is possible to prevent noise at the time of collision and misfeeding of the sheet at the time of collision due to rampage.

As described above, the number of steps p for driving the stepping motor 38 is calculated in S4, and the number of driving steps for the distance e for lowering the take-in roller 151 from the lowering position b to the sheet feeding position c. p2 and the like are required.
This is completed during the warming up when the copying apparatus becomes usable, and when this warming up is completed, the state of the paper feed start command is determined in S5 by operating the copy switch or the like.

When the feeding start instruction is output, the driving of the stepping motor 38 is started, and the distance from the standby position a to the descending position b obtained by the above-described calculation is increased at a high speed. The drive is controlled (S6) so that 151 is lowered. Next, at SS7, stepping motor 3
It is judged whether or not the count of the driving pulse number p1 of 8 is completed, and if the driving is completed, the stepping motor 38
Can be switched to low speed drive. When the number of drive pulses p2 in this low speed drive is counted, the intake roller 15
Assuming that 1 has reached the sheet feeding position c, the driving of the stepping motor 38 is stopped (S9).

Upon completion of this operation, the calling roller 1
The sheet feeding operation is started in a state where 51 is lowered and abuts on the uppermost portion of the sheet (S10). In this paper feeding, the feeding roller 151, the paper feeding roller 153, and the reverse separation roller 1
55 may be rotationally driven in advance when the take-in roller 151 is lowered, or may be started when the lowering operation is completed. The feed roller 151 including the paper feed roller 153 is rotationally driven by rotationally driving the paper feed drive motor 39.

When this sheet feeding operation is carried out, and after a certain period of time, or the sheet is fed by the pickup roller 151 and passes through the sheet feed roller 151 and the separation roller and the leading edge of the sheet reaches the conveyance roller 33, the sheet is called. The paper feeding operation by the insertion roller 151 is not necessary. Therefore, the stepping motor 38 is reversely driven so as to rise above the uppermost sheet (S11).
Let it. This reverse rotation drive is drive-controlled according to the step number p obtained as described above. Then, when finally returned to the standby position a (S12), the driving of the stepping motor 38 is stopped, and the take-in roller 151 is located at this position.
Is held. Regarding the rotation speed of the stepping motor 38 at this time, there is no problem even if it is driven at high speed.

Then, before starting the next sheet feeding, as described above, S
In 2, the distance L to the top of the seat is measured by the distance measuring sensor 35 and stored.

As described above, the call-in roller 151
The descent control is performed at a low speed at the distance e to the uppermost sheet, which is the descent position b, regardless of the distance to the uppermost surface of the sheet, and thus problems such as noise are eliminated as described above. Further, since the speed of lowering to the position of the distance e is driven at high speed, it is possible to shorten the time to reach the state of feeding.

FIG. 9 shows a time chart concerning the descent drive control of the intake roller 151 according to the first embodiment. In the figure, it is driven at high speed to the descending position b, and then the paper feeding position a.
Is driven at a constant speed. Further, in the descent control for the next sheet feeding, the sheet feeding position a is lowered according to the sheet thickness t. Further, the x mark indicates the timing of distance measurement by the distance measuring sensor 35.

(Embodiment 2) According to the above embodiment, the feeding roller 151 is always returned to the standby position a after the operation of feeding one sheet. Therefore, it is necessary to lower the sheet to the lowering position b before the uppermost sheet at the start of sheet feeding, and this descending distance tends to be long for each sheet feeding. Therefore, an embodiment for eliminating the descent time from the standby position to the descent position and achieving the purpose of starting the paper feeding operation will be described below.

When the first sheet is fed at the initial stage of the sheet feeding operation, the feeding roller 151 is moved to the sheet feeding position c as shown in FIG.
The control to descend to is performed. Then, step S1
FIG. 9 shows a control flow after the paper feeding operation at 0 is executed and the paper feeding operation is completed.

In the control, in order to separate the call-in roller 151 from the sheet P, the call-up roller 151 is raised to a position corresponding to the distance e corresponding to the lowered position b without returning to the standby position a. Let Therefore, in step S13, the stepping motor 38 is reversely driven by the number of steps corresponding to the distance e, and the driving of the number of steps by the reverse driving is completed (S14), and the driving of the stepping motor 38 is stopped. Call roller 1 in this state
51 is held at the descending position c for performing the next sheet feeding.

Then, before the next sheet feeding instruction is output,
Distance measurement is performed by the distance measuring sensor 35 (S15).
The timing of this distance measurement is as follows:
Is after, and the trailing edge of the sheet has passed through the loading tray 150, and before the feeding start instruction signal is output.
By obtaining the difference between the measured distance L1 and the distance L measured by the previous sheet feeding by the distance measuring sensor 35, the thickness t of the sheet fed last time can be known.

Further, since the feeding roller 151 is held at the lowered position b for the distance L1, after feeding the paper, the feeding roller 151 is added to the distance e plus the thickness t of the sheet. 151 is separated from the uppermost sheet P. Therefore, the distance e when held in the lowered position b
Then, the number of driving steps of the stepping motor according to the distance obtained by adding the sheet thickness t and the sheet thickness t is calculated by the above-described equation 2 (S17). Then, in accordance with the number of steps, a drive for lowering the take-in roller 151 by the stepping motor 38 is started (S19) in accordance with a paper feed instruction (S18).

This descent drive is the drive of the number of steps described above, and after the completion of the drive (S20), the take-in roller 151 comes into contact with the uppermost sheet, and the paper feeding operation in S10 is started. Become. After that, as shown in FIG.
This control flow is repeated until the feeding of the set number of sheets is completed. Then, when a series of paper feeding is completed, the intake roller 151 does not return to the standby position a and stops in the state of being held at the descending position b.

Therefore, the condition for holding the take-in roller 151 in the lowered position b is that it is held until the power is turned off.
When the power is turned on, the call roller 15 is set at the time of initial setting.
1 is initialized to the standby position a, and when the sheet feeding device is used, after the first sheet is fed, it is held at the descending position b as described above.

As described above, by making the take-in roller 151 stand by at the descending position a and controlling the descending and ascending, it is possible to reduce the impact when the take-in roller 151 collides with the uppermost sheet O, which causes a problem. Can be resolved as specified in Example 1 above. In addition, at the start of paper feeding, since the take-in roller 151 is raised by a certain distance e and is on standby, the time for the descent control for paper feeding can be shortened, so that the time for starting paper feeding is implemented. It can be shortened more than that of Example 1.

Here, in the second embodiment, when the feeding instruction is made, the lowering drive for contacting the uppermost sheet from the initial standby position a of the take-in roller 151 is performed in the first embodiment. Similarly to the above, the high speed drive is performed to the descending position a, and the low speed drive is performed for the remaining distance e. However, it is not necessary to control the drive in this way. That is, only when the first sheet is fed by the initial operation, and after that, the descent drive is performed by a distance commensurate with the distance e and the thickness of the sheet until the power is turned off. Roughness of paper can be prevented at the same time.

In particular, the distance e from the lowering position b to the paper feeding position a is set to, for example, 2 mm to 3 mm. When the stepping motor 38 is rotationally driven, the stepping motor 38 is stopped and controlled until the constant speed control is performed for high speed driving. Therefore, it is not necessary to drive the descent position b to the paper feeding position a at a low speed. As a result, the descent control of the distance e can be completed before the stepping motor from the second sheet starts up until it is driven at a constant speed.

FIG. 11 is a time chart concerning the drive control of the vertical movement of the take-in roller 151. The descending drive for the first sheet feeding is driven at high speed, and the raising control of the distance e is performed when the sheet is raised after the sheet feeding. It is carried out. Regarding the driving of this distance, the stepping motor 38 is driven with the number of steps p corresponding to the distance e, without particularly driving at low speed as described above. Then, the descending drive is controlled while the descending distance is corrected in accordance with the sheet thickness t for feeding the second sheet. It can be seen that the sheet feeding position a and the descending position b are descending according to the thickness of the sheet to be fed. Also, the timing of distance measurement is indicated by a cross.

Particularly, in the second embodiment, if the same descent control as in the first embodiment is performed from the time of driving the first sheet, noise and the like can be prevented from the first sheet.

Further, in the description of the second embodiment, the thickness t of the fed sheet paper P is obtained each time,
If the thickness t is twice or more or close to the thickness to obtained at the previous sheet feeding, it is determined that the sheet having the larger thickness is a double feed. Therefore, for the purpose of preventing the double feeding, it is possible to prevent the double feeding by setting the driving speed of the sheet feeding roller 153 and the invoking roller 151 to be slightly slower to ensure the separation driving.

Such control can be similarly performed in the first embodiment. That is, step S2 in FIG.
By performing the distance measurement at 2, the thickness t of the fed sheet can be obtained at the time of feeding the second sheet. The double feeding of the sheets can be determined by the thickness t of the sheet and the thickness to of the sheet according to the distance measured before feeding the third sheet. As a result of this determination, if the two are the same, it is determined that the double feeding is not performed, and if there is the above-described difference between the two, the double feeding is determined, and as described above, the feeding roller 151 and the paper feeding roller 153 are determined. The drive speed can be controlled.

Here, in the second embodiment, if the thickness t of the sheet is not different from the thickness to of the previous sheet to be fed, the thickness t of the sheet P is specified and the sheet is fed. If the subsequent take-up roller 151 is controlled to be raised by a distance (e−t) obtained by subtracting the thickness t from the distance e, the lowering control of the take-in roller 151 is controlled based on the distance e at the next paper feeding. it can. Therefore, it is not necessary to measure the distance by the distance measuring sensor 35 before feeding the paper. This is only the case where the thickness t of the sheet paper can be specified. Further, if the thickness t of the sheet to be fed is known in advance without obtaining the sheet thickness as described above, this thickness is input or stored in advance, and the thickness t is determined according to the thickness t. Thus, it is possible to control the descent distance described above.

As described above, the first and second embodiments are examples of the lowering control of the take-in roller 151 for performing the paper feeding, which is the basis of the present invention. In this example, various embodiments described below are possible.

In particular, when the feeding roller 151 is lowered to the sheet feeding position a and then the sheet feeding operation is executed, it is conceivable that the operation by the sheet feeding is not completely performed. That is, the fed sheet is fed by the feeding roller 153 after a predetermined time.
Or reaches the position of the transport roller 33. At this time, the detection sensor (56) shown in FIG. 1 for detecting the sheet conveyance state is arranged in the conveyance path before the paper feed roller 153 or before the conveyance roller 33. When the detection sensor (58) is not detected after a predetermined time in response to the feeding drive of the feeding roller 151, the CP is detected.
On the side of U40, a paper feed failure, that is, a wrong paper feed is determined by not inputting a signal from the detection sensor (58).

Therefore, the CPU 40 discriminates the above-mentioned paper feed error, and increases the distance for lowering the take-in roller 151 at the next paper feed for the purpose of preventing the paper feed error. . In other words, when controlling the descent,
The stepping motor 38 is rotationally driven in a state in which a few more steps are added to the number of steps obtained from the above equation 2. This further lowers the take-in roller 151 from the sheet feeding position where the sheet comes into contact with the sheet.

From the above, the pressure contact force between the intake roller 151 and the uppermost sheet P is increased, and the sheet feeding force is strengthened. As a result, it is possible to eliminate the previous paper feeding error and enable a reliable paper feeding operation. In this respect, in the related art, when the loading roller is placed by its own weight, the pressure contact force is always constant, so that the action and effect of the present invention cannot be obtained.

Further, according to the second embodiment, when the sheet to be fed is exhausted, for example, the loading tray 150 is pulled out and the sheet is loaded in order to replenish the sheet. At this time, if the pull-in roller 151 is kept at a distance e from the uppermost sheet, it may be an obstacle when pulled out. In particular, the loading tray 150 cannot be pulled out, and the loading tray 150 and the intake roller 151 may be damaged by forcibly pulling out the loading tray 150.

Therefore, when the tray 150 is pulled out, the state in which the tray 150 is pulled out is detected by the detection sensor 55 composed of the micro switch or the like in FIG. In response to this detection, the copying machine body side
Under the present circumstances, the paper feeding operation of the mounting tray 150 is invalidated and the paper feeding operation by the other mounted paper feeding device 15 is enabled. Therefore, in response to the detection of the pull-out, the take-in roller 151 is driven to rise. This drive is a drive for returning from the lowered position b to the initial standby position a. Such a pulling-out operation is performed not only when the sheet is replenished but also when the sheet size is exchanged.

After the sheet is replenished or exchanged as described above, when the paper feed tray 150 is mounted, this is detected by the detection sensor 55. In response to this detection signal, the distance measurement sensor 35 measures the distance (L) to the uppermost sheet, and based on this measured distance, the distance e before the contact roller 151 comes into contact with the sheet P in advance. It is also possible to descend to the descending position b located at.

Next, the distance measuring sensor 35 needs to measure the distance while the seat is stationary. In other words, if the accurate distance is not measured, the call roller 1
The control for lowering 51 to the position where it abuts the seat cannot be performed accurately. Therefore, in the above description, the distance measuring sensor 3
The timing for measuring the distance in 5 is in the stationary state before the paper feeding. For example, as shown in FIG. 9 or FIG. 11, the process is performed after the intake roller 151 is separated from the sheet. On the other hand, by performing the distance measurement in a state where the invocation roller 151 is in contact with the sheet, more accurate distance measurement can be performed.

Therefore, at the time of the initial sheet feeding, that is, in step S2 of FIG. 8, since the pickup roller 151 is not in contact with the sheet and the distance to the uppermost portion of the sheet is unknown, the measurement is performed. , Descent control is executed. Then, the distance measuring sensor 35 is driven after a lapse of a certain time after the sheet is brought into contact with the pull-in roller 151 to measure the distance. The certain period of time is a period of time in which the sheet is agitated (vibrates) to some extent in the abutting state when the driving of the sheet feeding roller 153 and the intake roller 151 is stopped, but the agitation is stopped. The fixed time is usually about 0.1 sec, and 0.3 sec is sufficient time to exclude the influence of vibration.
The degree is reasonable.

As described above, the distance is measured by the distance measuring sensor 35 after the time of 0.3 sec, for example. This measurement distance is the timing when the paper can be fed, and the take-in roller 151 has already been lowered to the paper feeding position c. Therefore, when the lowering control for the next sheet feeding is performed according to the measured distance after the sheet feeding is completed, the thickness t of the sheet fed is not corrected. For that purpose, it is necessary to know the thickness t of the fed sheet.

Therefore, the take-in roller 151 is lowered to 2
After the feeding of the first sheet is completed, the difference between the distance L3 measured for feeding the next third sheet and the distance L2 measured before feeding the second sheet causes the sheet It is possible to know the thickness t. In the second embodiment, the thickness t is added to the distance e to obtain the corrected descent distance, and the rotation step number p of the stepping motor 38 is calculated in accordance with this. As a result, for the third sheet feeding, the descent control can be performed while the distance to the sheet surface is accurately measured.

Here, the descent control for feeding the first sheet is based on the condition that the distance to the uppermost portion of the sheet is measured before the pull-in roller 151 contacts the sheet. The descent control for sheet feeding is conditioned on the measurement distance when the sheets are in contact. At this time, the sheet thickness t
The distance has not been corrected according to. To that end,
The descent control is performed so as to correct the average value or the maximum thickness of the sheet used. Then, the second sheet is fed, and the thickness t is obtained by the difference between the distance L3 measured before feeding this sheet and the distance L2 measured before feeding the previous first sheet. Accurate distance correction can be performed by the thickness t.

By performing the distance measurement in the state where the invocation roller 151 is in contact with the sheet in this way, compared with the distance measurement to the top of the sheet in the state where nothing is done, the sheet fluctuation which is the measurement object is changed. Can be performed in a small amount, and accurate distance measurement can be performed. Therefore, more accurate descent control is possible. At the time of this distance measurement, the intake roller 151 is controlled to be in a stopped state, and the paper feeding operation is started after the measurement.

In the distance measurement in the state where the call-in roller 151 is in contact with the sheet, when the second sheet is fed, the previously measured distance L1 and the distance L2 measured before the second sheet is fed. As described above, the thickness t of the sheet can be obtained from the difference. Therefore, in this distance measurement, more accurate distance measurement can be performed by obtaining an average value of a plurality of measurement results or specifying the maximum value of the measurement distance as the measurement result, instead of a single measurement result. By specifying the maximum value of the measurement distance as the measurement result, it is possible to surely bring the sheet into contact with the sheet in the descent control of the intake roller 151. That is, if it is the minimum value of the measurement result,
It is conceivable that the descent is insufficient and the intake roller 151 is slightly separated from the sheet.

Further, also in the measurement in the state where the intake roller 151 is in contact with the sheet, the measurement can be similarly performed a plurality of times, and the average value or the maximum value can be used as the measurement result.
In this case, it is conceivable that the distance measuring sensor 35 measures the position where dust such as dust exists on the upper surface of the sheet or between the sheets. For the purpose of removing this factor, the distance measurement is performed a plurality of times while the paper feeding operation is performed. If the average value or the maximum value of this measurement distance is specified as the measurement result, the sheet moves from the paper feed, so that the above-mentioned dust and the like can be eliminated.

According to the above description of Embodiments 1 and 2 and the embodiments based thereon, the distance measuring sensor 35 is installed in the paper feeding device 1.
5 are arranged in a fixed state corresponding to the sheets to be placed. The object of the present invention can also be achieved by providing the distance measuring sensor 35 on the side of the upcoming roller 151 that moves up and down.

For example, the distance measuring sensor 35 is connected to the invocation roller 1
It is fixed to the arm 152 holding the rotary shaft 151-1 of 51 via a mounting member. At this time, the distance measuring sensor 35 is arranged so that it can be detected from the center of the roller shaft 151-1 to the top of the sheet.

Therefore, if the measurement distance L is subtracted from the radius r4 of the taking-in roller 151, the distance Lo between the taking-in roller 151 and the portion facing the sheet can be obtained. Moreover, it is not necessary to calculate the number of steps of the stepping motor 38. That is, the distance is constantly measured during the descent, and when the descent position b corresponding to the predetermined distance e before contacting the sheet is measured, the take-in roller 15 is measured.
The descent rate of 1 can be controlled to be slow.

This is because the distance between the sheet and the intake roller 151 can always be measured and the descent speed can be controlled to be slow after the distance e is measured, without being approximately calculated as in the above-described equation 2. , Enabling more precise control.

Further, when lowering the take-in roller 151 existing at the initial standby position, control is performed based on the above-described calculation formula 2 according to the measured distance L, and before the driving is stopped based on the formula. It is also possible to determine whether or not the actually measured distance is e, and control the descent rate after this determination.

Further, even when the feeding roller 151 is raised after the paper feeding is completed as in the second embodiment, the reverse driving of the stepping motor 38 can be stopped based on the result of the actual measured distance e. it can. Then, if the distance measurement is performed again, the measured distance after the previous sheet feeding is measured by the difference between the distance e measured at the time of rising and the thickness of the fed sheet. The difference is the thickness of the fed sheet, and if the thickness t1 is more than twice the sheet thickness t before the previous feeding, it can be determined that the sheet is double-fed.

Similarly, if it is determined that the preceding sheet is defective in sheet feeding, the distance e is lowered in order to increase the pressure contact force of the feeding roller 151 with the uppermost sheet in the current sheet feeding. And slightly larger than the distance e, the stepping motor 3
It is also possible to stop by increasing the number of steps of 8.

Here, the thickness t of the fed sheet cannot be known when the first sheet is fed, and the lowering control of the take-in roller 151 based on the correction distance based on the thickness t cannot be performed. Particularly, after the power is turned on, the selected paper feeding device 1
In the initial feeding of No. 5, the thickness of the first fed sheet cannot be measured until the second sheet is fed. Further, when the preload roller 151 is brought into contact with the sheet and the distance is accurately measured, the sheet thickness can be specified only before the third sheet is fed. Further, in order to determine whether the fed sheet is a single sheet or a double feed, it is determined before the fourth sheet is fed.
The descent control of (1) processes the thickness of the sheet used (for example, the maximum thickness used) or measures the measured thickness t as an accurate one.

Therefore, at the time of initial sheet feeding, the sheet thickness t measured at the time of feeding the second and subsequent sheets or the third and subsequent sheets.
Although it is possible to perform the correction control of the descending distance of the call-in roller 151 according to the above, the descending position is controlled by prediction or the like for the first sheet or the second sheet. Therefore, the average value or the maximum thickness of the sheet thickness data used in the copying apparatus is stored in advance as an initial value, and the descent control at the time of feeding the first or second sheet is performed by the initial value. . And
In feeding the second or third sheet and thereafter, the lowering of the feeding roller 151 to the sheet feeding position a can be controlled according to the measured thickness t.

At this time, when the sheets stacked on the loading tray 150 are replaced or replenished, the loading tray 15
If the user is informed of the sheet thickness t and the sheet size used for the loading tray 150 when 0 is pulled out, the user can set the sheet thickness t and the sheet size suitable for the sheet thickness t and the sheet size. From the first sheet, it is possible to control the lowering of the intake roller 151 according to the replenished sheet thickness t.

For that purpose, the size of the sheet paper P is detected, and the sheet thickness t corresponding to the size is simultaneously calculated as R.
It is stored in a predetermined area such as AM. At the same time, the cumulative number of fed sheets corresponding to the sheet size and thickness is also stored at the same time. As an example of this stored content, as shown in FIG. 12, the size and thickness t of the sheet that has been fed recently is first, and the size and thickness t of the preceding sheet fed in terms of time are later described. The display device 52 shown in FIG. Further, the number of fed sheets corresponding to the sheet size and the thickness may be similarly displayed.

Therefore, when the size of the fed sheet is changed, the loading tray 150 is pulled out. When the drawer is detected by the detection sensor 55, the stacked sheet sheets are removed, sheets of a desired size are stacked, and the replacement is completed, whereby the mounting tray is mounted. The size of the stacked sheets is detected by the detection sensor 55 detecting this mounting, and the sheet thickness t corresponding to the detected size is searched for in the stored size as shown in FIG. 12, and the search is performed. According to the result, the display device 52 displays the paper thickness t together with the size. At this time, the user operates the operation keys 54 in advance to specify the sheet thickness of the size to be used, based on the display content. As a result, it is possible to accurately control the lowering of the invoking roller 151 in the sheet feeding from the first sheet according to the sheet thickness without detecting the thickness of the sheet to be fed. The measured sheet thickness t is cumulatively added and stored in the storage area corresponding to the sheet size and the sheet thickness.

Here, regarding the display of the sheet thickness corresponding to the sheet size, the sheet of the size detected by the replacement that has been fed immediately before is displayed first. Or, start with the sheet with the most number of paper feeds,
For example, for the A4 size, by displaying the contents of the memory number 2 first, the user can easily input the designation of the thickness.

On the other hand, the replacement of the sheet size, not the replacement of the sheet size, is performed when the sheets on the loading tray 150 are exhausted. Therefore, when the mounting tray 150 is pulled out and the sheets are replenished in a state in which the other sensor 56 detects that the mounting tray 150 is out of paper,
The loading tray 150 is mounted. At this time, it is possible to display a sheet thickness t corresponding to the size to be replenished and give a message to replenish a sheet having the same thickness as the sheet thickness t. If the same size as the size of the previously fed sheet is replenished when this mounting is detected, the display allows the user to specify and input the thickness of the size sheet with the operation key 54. And, as mentioned above, 1
From the time of feeding the first sheet, the lowering control of the intake roller 151 can be performed according to the sheet thickness.

As described above, when the sheet paper is replaced or replenished, the sheet thickness is designated in advance,
It can be controlled in advance from the time of feeding the first sheet. In the display for that purpose, the above-mentioned control is performed by accumulating and storing the size of the sheet that has been involved in the sheet feeding and the thickness corresponding to the size, and displaying the content according to the replenishment or replacement work. I'm trying to do. However, displaying all the stored contents increases or decreases the burden on the user side. For this reason as well, it is possible to reduce the burden on the user side by searching the storage unit for a sheet having a thickness corresponding to the replenished or replaced size and displaying this. Also, in this display, the size of the cumulative number is displayed first, or the size of the sheet fed immediately before the work such as replacement is displayed, thereby further reducing the burden on the user side. However, it is possible to reduce mistakes in designation.

[0130]

According to the sheet feeding apparatus of the present invention, in the lowering control of the feeding roller for feeding the vertically moving sheet to the sheet feeding position, the sheet is fed before the uppermost sheet is abutted. It makes a light contact with. for that reason,
The noise at the time of collision can be prevented, and the sheet can be stably fed by preventing the sheet from being violent at the time of collision.

In the descent control, by always lowering the descent speed when descending from a predetermined distance,
The above effects can be obtained. Further, by setting the position at which the feeding roller is raised after feeding the sheet to a predetermined distance before the contact, it is possible to shorten the descent time until the start of sheet feeding, and thus to shorten the sheet feeding start time. Further, if a paper feed failure occurs, the descent control can be performed so as to increase the pressure contact force when the feeding roller abuts against the sheet from the next paper feed, so that the paper feed failure can be prevented each time.

Moreover, by performing the correction control of the lowering of the call-in roller according to the thickness of the sheet to be fed, the call-in roller and the sheet are surely brought into contact with each other to cause a paper feed failure. It enables stable paper feeding. Here, since the thickness of the sheet fed by the distance measuring sensor can be obtained, correction control can be performed according to the obtained thickness.

[Brief description of drawings]

FIG. 1 is a block diagram showing a control circuit configuration in a copying apparatus of the present invention.

FIG. 2 is a schematic configuration diagram in which a sheet feeding device is provided in a copying apparatus according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a specific example of the paper feeding device of the present invention.

FIG. 4 is a perspective view showing a specific example of the paper feeding device of the present invention.

FIG. 5 is a sectional structural view showing the structure of a PSD sensor for explaining the details of a specific example of the distance measuring sensor according to the present invention.

6 is an equivalent circuit diagram of the PSD sensor of FIG.

FIG. 7 is a diagram for explaining the principle of distance measurement according to the present invention.

FIG. 8 is a control flow chart for lowering and raising the take-in roller for sheet feeding according to the present invention.

9 is a time chart of vertical movement of a take-in roller under the control of FIG.

FIG. 10 is a flow chart showing another example for lowering and raising the take-in roller for feeding sheets according to the present invention.

11 is a time chart of vertical movement of the call-in roller according to FIG.

FIG. 12 is a diagram showing an example of accumulating and storing a paper feed status according to the present invention.

FIG. 13 is a cross-sectional view showing an example of a conventional paper feeding device.

14 is a perspective view of the paper feeding device of FIG.

FIG. 15 is a cross-sectional view showing another example of a conventional paper feeding device.

16 is a perspective view of the paper feeding device of FIG.

[Explanation of symbols]

 15 Sheet Feeding Device 150 Loading Tray 151 Calling Roller 152 Supporting Roller Arm 153 Feeding Roller 155 Reverse Separation Roller 152-1 Fan Gear 37 Drive Gear 35 Distance Measuring Sensor 38 Stepping Motor 40 CPU (Control Means) P Sheet paper to be fed

Claims (5)

[Claims] 1. A loading tray on which sheets are stacked, an up-and-down movable roller for feeding the sheets on the loading tray, and a paper feed for abutting the up-rolling roller with the sheets. In a sheet feeding device having a moving mechanism that moves between a position and a standby position separated from the sheet, a distance measuring sensor that measures a distance to the uppermost portion of the sheets stacked on the placement tray, The moving mechanism is controlled, and based on the distance measured by the distance measuring sensor, a predetermined descending position before the contact roller comes into contact with the sheet is determined, and high-speed driving is performed up to the determined descending position. A sheet feeding device comprising: a control unit configured to control the descending speed of the invoking roller from the descending position until the sheet comes into contact with the stacked sheets. 2. A loading tray on which sheets are stacked, an up-and-down movable roller for feeding sheets on the loading tray, and a paper feed for abutting the up-rolling roller with the sheets. In a sheet feeding device having a moving mechanism that moves between a position and a standby position separated from the sheet, a distance measuring sensor that measures a distance to the uppermost portion of the sheets stacked on the placement tray, The moving mechanism is controlled, and the pull-in roller is driven down to a position where it contacts the stacked sheets based on the distance measured by the distance measuring sensor, and after feeding, it is separated from the sheet contact position at that position. A sheet feeding device, comprising: a control unit that stops the intake roller at a lowered position between the standby position and the sheet feeding position when the sheet feeding device is raised to the position. 3. The descending drive according to claim 2, wherein said control means corrects the descending distance from the descending position of the intake roller in accordance with the thickness of the sheet to be fed and performs descending drive. Sheet feeding device. 4. The thickness of the fed sheet is the difference between the distance measured after feeding the sheet and before the next feeding and the distance measured when feeding the previous sheet. Seeking
4. The sheet feeding apparatus according to claim 3, wherein the descending distance of the intake roller from the descending position is corrected and controlled according to the thickness. 5. A sheet detecting means for detecting a sheet feeding state of a sheet fed by the take-in roller is provided, and the control means responds to a detection result of the sheet detecting means at the time of the next sheet feeding. 3. The sheet feeding apparatus according to claim 1, wherein the descending drive distance from the descending position of the take-in roller is corrected, and the press contact force of the take-in roller with respect to the sheet is corrected and controlled.