JPH07101566A - Sheet feeding device - Google Patents

Abstract

PURPOSE:To accurately hold a paper sheet at a topmost part in a predetermined specified position by elevating a placing tray through utilization of an elevation mechanism and grasping a topmost part paper position to control elevation. CONSTITUTION:A paper topmost part surface is irradiated with light by a distance measuring sensor 20. Reflection light thereby is received by a light receiving means, a distance from the sensor 20 to a topmost part is measured from a light receiving condition, and position relation between a paper document on a placing tray 2 and a conveyance belt 17 is discriminated. A measurement distance based on the sensor 20 is in a constant state, air for a feed belt 4 is discharged, and through the starting of suction operation, feed operation is started. In this case, until a predetermined position is detected by the sensor 20, a motor for drive coupled to an elevation mechanism is driven and controlled and running of the motor is stopped in response to detection of the specified position. This constitution holds the topmost part of placed paper sheets in a determined specified position.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for feeding a sheet cut to a predetermined size to a predetermined position, for example, feeding a sheet original or the like to a reading position, or feeding a sheet of paper to an image forming position. The sheet feeding device that is fed with
The present invention relates to a sheet feeding device that holds a top sheet placed in a placement trouble at a constant height (position) and enables stable feeding.

[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 copying apparatus, a document is placed at a predetermined position, that is, an exposure position which is a document reading position, and the document at the exposure position is projected on a recording medium. In this case, in order to save the trouble of manually placing the sheet original at the exposure position, the sheet original is placed on the original placing tray, and the sheet original on the original placing tray is moved to the exposure position. There is a copying machine equipped with an automatic document feeder that automatically conveys.

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-conveyed to the exposure position again to form an image. Some are put back on the document tray. In this way, the sheet document is returned from the document placing tray to the exposure position, and from the exposure position to the document placing tray.
Called DH).

Further, in addition to the feeding of the sheet original, the image forming apparatus transfers the image formed on the photosensitive member, which is a recording medium, in particular, the toner image to the sheet in order to transfer the image onto the sheet. A sheet feeder is provided for feeding to the position. As this sheet feeding device, besides using a friction roller, for example, JP-A-60-8253 is used.
As disclosed in Japanese Patent Publication No. 7-62 (Japanese Patent Publication No. 62-56056), there is also one that feeds a sheet of paper placed on a placing tray by air means, that is, air blowing and air suction. According to this apparatus, for example, in order to perform sheet feeding, the pressure for sucking the uppermost sheet is controlled to ensure single sheet feeding.

As described above, the image forming apparatus is provided with a device for feeding a sheet original and a feeding device for feeding a sheet of paper, and automatically feeds them as needed.
In this case, as shown in FIG. 11, a loading tray 32, on which a large number of sheets 31 are loaded, is provided to be vertically movable by an elevating mechanism, and the uppermost portion of the sheets 31 is raised to a prescribed height (position). Then, the sheet 31 at that position is fed by using a feeding roller or an air feeding means (not shown) provided facing the upper part.

In order to hold the uppermost portion of the seat 31 at a fixed position, a height detection switch 33 is provided, and in response to an OFF (or ON) operation of the switch 33, a driving means for an elevator mechanism (not shown). Then, the motor is rotated to raise the loading tray. Then, the detection switch 33 becomes O
By turning N (or OFF), the rotation of the motor is stopped, and the raising of the loading tray is stopped, so that the uppermost sheet is always held at the specified position.

[0008]

However, according to the conventional raising / lowering operation of the loading tray, since it responds to the ON / OFF operation of the detection switch composed of the micro switch, the range of the specified position is large and the feeding position is large. It cannot be held in the proper position for feeding. That is, since a mechanical switch is used, the difference in response to turn on or off is very large. For example, the point a at which the switch turns on from the off state
The difference between the ON state and the OFF point b is very large. Therefore, the uppermost part of the sheet moves up and down within the range of this response, which causes a large difference in the feeding force during feeding, and stable feeding cannot be performed.

Therefore, the operation piece of the switch 33 is devised so as to reduce the response difference, and the arrangement position of the switch 33 is adjusted, but these are very troublesome works.

Further, this response difference is different for each detection switch, and it is very difficult to accurately keep the position of the uppermost portion of the seat within the specified position, and at the same time, the adjustment for that is very troublesome. It was

Moreover, due to the inertial force of the drive motor constituting the lifting mechanism, even if the motor is stopped and controlled while the detection switch 33 is ON, the loading tray 32 will be slightly lifted. Therefore, the position of the uppermost sheet becomes higher than the point a in FIG. 11, and the sheet cannot be held within the specified position range. Moreover, it is placed (set) on the placing tray.
Even if the amount of sheets to be loaded (laden weight) or the like is increased, the amount of rise after stopping the drive motor is not constant, and the position of the uppermost sheet cannot be held constant.

Therefore, the idea of holding the uppermost sheet at a predetermined position without providing the detection switch shown in FIG.
JP-A-60-56736 (Japanese Patent Publication No. 62-5605)
No. 2). This is a means for feeding air, and controls the lifting mechanism in response to the time for sucking the uppermost sheet by air.

However, even in such an apparatus, since the position of the uppermost sheet is not directly detected, there is no guarantee that the sheet is held at a constant height. Moreover,
If the thickness of the placed sheet (one sheet having a different weight) is different, the time for sucking the sheet is different, so that the positioning of the uppermost portion of the sheet becomes unstable. Further, in the suction of air and the like, a change in the external atmospheric pressure, for example, in the highland and the flatland is different, and at the same time, a change in the suction force causes a large difference in the time for sucking the uppermost sheet.

As described above, when the uppermost sheet is held at the position within the specified range without detecting the height of the uppermost sheet, it is limited to air feeding, and a friction roller is used. Was not applicable, or it was very difficult to position it accurately within the specified range.

Moreover, according to the above-mentioned conventional apparatus, when self-diagnosis of a failure (trouble, etc.) of the drive unit including the lifting mechanism, the motor of the drive unit is energized, and the current and rotation speed at that time are determined. It can be done by detecting. However, this requires extra time because the self-diagnosis is performed by setting another mode. Moreover, this self-diagnosis is completely different from controlling the position of the uppermost portion of the seat, and the self-diagnosis cannot be performed by controlling the uppermost portion of the seat.

In view of the above-mentioned problems, the present invention provides a sheet feeding apparatus capable of accurately holding the uppermost sheet on the loading tray at a predetermined prescribed position (reference position). To aim.

Another object of the present invention is to enable self-diagnosis of the means for raising and lowering at the same time when the uppermost portion of the seat is held in a prescribed position.

[0018]

According to a first aspect of the present invention, there is provided a sheet feeding device which is vertically movable through an elevating mechanism for placing a sheet cut to a predetermined length. The loading tray to be moved, the feeding means for feeding the sheet on the loading tray to a predetermined position, and the lifting mechanism for holding the uppermost sheet on the loading tray at the specified position. A sheet feeding device having a driving means for driving and raising and lowering the loading tray, including position detecting means for detecting a position up to a topmost sheet placed on the loading tray, and the position detecting means. Control means for controlling the drive means on the basis of the position detection by the above, and moving the uppermost sheet on the placing tray to a specified position.

Further, in the sheet feeding device according to the present invention, the position detecting means is composed of a distance measuring sensor for measuring a distance to the uppermost sheet.

Further, in the apparatus according to claim 1, the control means controls the driving means based on a comparison between a reference distance applied to a specified position and a measurement distance measured by a distance measuring sensor which is the position detecting means. Is characterized by.

Further, in the sheet feeding apparatus according to the first aspect of the invention, the reference distance is keyed in and stored.

Further, in the sheet feeding device according to claim 1, the control means measures the distance of the uppermost sheet at the time of stop control by the reference distance when the drive control of the driving means is performed based on the reference distance. The reference distance is corrected using the difference between the measured distance and the reference distance as a correction value, and the drive means is drive-controlled based on the correction.

According to a sixth aspect of the present invention, there is provided a sheet feeding device which is vertically movable for placing a sheet cut to a predetermined length and is vertically moved by an elevating mechanism. A tray, a feeding means for feeding a sheet on the loading tray to a predetermined position, and the lifting mechanism for driving the lifting mechanism to hold the uppermost sheet on the loading tray at a specified position. In a sheet feeding device provided with a driving means for raising and lowering a tray, according to a distance measuring means for measuring a distance to an uppermost sheet placed on the placing tray and a distance measured by the distance measuring means. Control means for controlling the drive means to move the uppermost portion of the placing tray to a specified position, and the distance to the uppermost sheet by the distance measuring means during vertical movement of the placing tray by the controlling means. To measure When the measured distance is not changed after a predetermined time, characterized by comprising a diagnostic unit formed by the self-diagnosis as a trouble of the drive means.

[0024]

According to the sheet feeding apparatus of the first aspect of the present invention, in order to feed the cut sheet placed on the placing tray, the feeding means operates to feed the uppermost sheet. I do. Prior to the feeding operation, in order to hold the uppermost portion of the placed sheets at a constant position, the placing tray is raised via the elevating mechanism. That is, the control means drives and controls the drive means, which is a motor, based on the position detection up to the uppermost position of the sheet, and the drive of the drive means is stopped by the position detection means detecting a prescribed position. . Thereby, the uppermost position of the seat can be controlled to a predetermined position. In particular, by providing a distance measuring sensor for measuring the distance to the uppermost portion of the seat as the position detecting means, the control means can drive-control the driving means according to the measured distance. And
The driving operation of the driving means is stopped in a state where the distance measured by the distance measuring sensor has moved to a reference distance which is a predetermined prescribed position.

The reference distance is keyed in advance by the key input means and stored. Therefore, the difference between the individual devices can be guaranteed by this. In this case, the range of the specified position has a certain width, and as the control target, the width, that is, the upper limit and the lower limit values are key-inputted and stored, and the control can be performed within the range. . If the inertial force of the driving means poses a serious problem, the reference distance may be corrected. For example, the driving unit is stopped at the reference distance, the distance to the uppermost portion of the sheet is measured after stopping, and the reference distance is corrected using the difference between the measured distance and the reference distance as a correction value. After that, by controlling the stop timing of the drive means with the corrected reference distance, drive control can be performed in anticipation of inertial force. Can be corrected. That is, the position of the uppermost sheet can be set to a predetermined value by correcting the measurement distance for a predetermined position and correcting the timing.

In particular, according to the distance measuring sensor, there is no difference in the ON-OFF operation timing unlike a mechanical switch, and the control means can respond in response to a predetermined position detection, so that accurate position regulation can be performed. You can do it.

Further, according to the sheet feeding apparatus of the sixth aspect of the present invention, in the state where the ascending / descending operation is performed via the ascending / descending mechanism based on the distance measured by the distance measuring sensor, When the measured distance remains constant and does not change, the failure state of the lifting mechanism including the driving means can be self-diagnosed. That is, the self-diagnosis can be easily performed by using the measurement distance from the distance measurement sensor and the normal control operation of performing the elevation drive control based on this distance. Therefore, it is not necessary to separately set the self-diagnosis mode, and it is possible to save useless time and another configuration for that purpose.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a sheet feeding apparatus for cutting sheets of a predetermined size 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. That is, it can be applied to all devices for feeding cut sheets to a predetermined position. In particular, the present invention can be applied to a feeding device that feeds a sheet of paper on a loading tray to a transfer position in an image forming apparatus to process a sheet, a document feeding device that feeds a sheet document to a reading position, and the like.
Further, not only the image forming apparatus such as the copying apparatus and the printer but also the facsimile and the like can be applied to the feeding apparatus for feeding one sheet of the transmission document to the reading position, and further, the recording apparatus can be used. It can also be applied to a device for feeding a sheet of paper to a recording position. In short, the present invention can be applied to a sheet feeding device in which a sheet is placed, the placing tray 2 is moved to a prescribed position, and the feeding operation is performed at that position.

FIG. 1 is a sectional view showing a specific example of the sheet feeding apparatus of the present invention applied to a copying apparatus, and FIG. 2 is an example in which the sheet feeding apparatus shown in FIG. 1 is applied to a document circulation feeding apparatus (RDH). FIG.

In FIG. 1, the copying apparatus is a sheet circulating apparatus (RDH) 30 which is a sheet feeding apparatus having an original placing tray for placing sheet originals on the upper portion of the copying apparatus main body.
Is equipped with.

The sheet-shaped original 1 is placed on the original placing tray 2. The loading tray 2 is provided so as to be movable up and down, and is vertically moved via a not-illustrated conventionally known lifting mechanism. As the elevating mechanism, for example, means for converting the rotation of the drive motor into vertical movement is provided, and the means is connected to the mounting tray 2. Known means for converting the vertical movement include, for example, a large number of pulleys, a wire wound around the pulleys, a large number of rotating gears, and the like. The well-known mechanism is used as it is without any features, and its details are omitted.

The presence or absence of a sheet original placed on the placing tray 2 is positioned by an operating piece of a microswitch 3 for detection fixed to a vertically moving placing tray. The operation piece is pushed down by the document placed on the placing tray 2 to operate, and the presence of the document is detected. Further, when the sheet document is set (placed) on the placing tray 2, the placing tray 2 is lowered to the lowermost position, and the detection switch 19 for detecting this position is
It is fixedly provided on the apparatus main body side, that is, on the RDH main body side.

Therefore, when setting on the placing tray,
The loading tray is lowered to the lowermost position and can be loaded in this state. When this lowermost position is detected by the detection switch 19, the drive motor for vertically moving the loading tray 2 is stopped, and further lowering is prohibited. Then, when a sheet is set on the loading tray 2, this is detected by the detection switch 3, and the raising operation is started by the rotation of the drive motor (forward rotation), and the uppermost sheet original 1
Is raised to a specified position and stopped at that position.

Further, in order to feed one sheet of paper to the image forming position in the copying apparatus, the same construction as the sheet feeding apparatus of FIG. 1 is used, and the loading tray 2 is provided so as to be able to be pulled out from the apparatus main body. Some are configured to facilitate the placement of sheets on the tray, ie, the set operation. Further, there is also a cassette system in which the loading tray itself is replaceable, that is, a loading tray is provided in a replaceable cassette body.

On the original placed on the tray 2 described above, a feeding belt 4 as a feeding means for sequentially feeding the uppermost sheet original 1 is arranged. The feeding belt 4 is internally provided with a part of suction means for sucking air. The uppermost sheet original 1 is sucked (adsorbed) to the belt by air suction, and the sheet original is fed by moving the belt. To send. Along with the feeding belt 4 which is a feeding means, an air blowing means which constitutes an air ejecting means for separating the stacked originals placed on the original placing tray 2 into each one and reliably feeding one sheet An exit 5 is provided. This air outlet 5 is the front surface of the placed document (the front surface in the feeding direction).
More air is blown to separate the stacked sheet originals 1 from each other. The uppermost one of the sheet originals 1 separated by the air blowing from the air outlet 5 is sucked onto the feeding belt 4 by suction means,
The original 1 is fed by rotating the belt 4 in the direction of the arrow.

As shown in FIG. 2, the fed sheet original 1 is fed along a conveyance path 6 formed by a guide plate, and is conveyed by various conveyance rollers 7 arranged in the middle of the conveyance path. They are transported one after another. An exposure unit 8 for projecting an image of the sheet original 1 on the surface of a photosensitive drum, which is a recording medium provided in the main body of the copying apparatus and is rotationally driven, is disposed in the middle of the conveying path. The exposure unit 8 has a transparent plate 9 such as glass, and an exposure light source for irradiating light from below the transparent plate 9 is arranged. The copy image surface (lower surface) of the original document 1 conveyed to the position of the exposure unit 8 is pressed by the pressing roller 10 or the like from the opposite surface and is conveyed at a constant speed.

The original document 1 that has passed through the exposure section 8 is further conveyed through the conveying roller 7c, and the original document tray 1 is placed.
It will be returned to the lower part of the and will be circulated again. When the document 1 is circulated and conveyed, the upper and lower surfaces of the document 1 are inverted and returned to the document tray 1. Therefore, when the document 1 is a double-sided document, the document is fed in the first circulation (odd circulation). One side (front side) of the second side (the even number side) is presented to the exposure section 8 on the opposite side (back side), and images on both sides are read and can be projected onto, for example, a photosensitive drum.

In the case of a single-sided original, the original 1 can be returned to the original tray 1 by turning it over before returning it to the original tray. Therefore, FIG.
In addition, a reverse conveyance path is further provided in the original conveyance path of, and the reverse conveyance path is selected when reading an image of a single-sided original,
For a double-sided original, the path shown in FIG. 2 may be selected and circulated.

The above is the R equipped with the sheet feeding apparatus of the present invention.
1 is a schematic configuration of DH30. A copying apparatus main body (not shown) is located below the RDH 30. That is,
The main body of the copying apparatus is provided with an optical system for irradiating the transparent plate 9 constituting the exposure section 8 with light and projecting it onto the surface of the photosensitive drum. This optical system includes a copy lamp such as a halogen lamp, a plurality of mirrors, a zoom lens, and the like, and projects the image of the original document 1 conveyed to the transparent plate onto the photosensitive drum.

Below the optical system, a drum-shaped photosensitive drum is rotatably arranged. Various devices for forming an image are arranged around the photosensitive drum. For example, a charging unit, a developing unit, a transfer unit, a cleaning unit, a static eliminator and the like are arranged, and the exposure by the optical system is performed between the charging unit and the developing unit. Therefore, on the photosensitive drum, an electrostatic latent image corresponding to the original image by exposure is formed, the image is developed with toner, and the sheet paper appropriately fed by the transfer device is transferred, and then the sheet paper is transferred. Is separated from the photosensitive drum surface and conveyed to the fixing unit,
After that, it is ejected to the outside of the copying machine.

At this time, when an image is further formed on a sheet of paper on which an image has been formed, for example, when an image is to be formed again on the opposite side of the sheet of paper on which the image has been formed, the sheet of paper is temporarily discharged without being discharged. The sheet is conveyed to the tray, and the sheet is again fed from the intermediate tray to the transfer position.

In order to expose an image on the photosensitive drum as described above, it is necessary to feed the sheet original 1 placed on the original placing tray 2 by the feeding belt 4 and feed it to the exposure section 8. There is. Therefore, FIG. 1 shows the details of the structure of the air discharging means including the air outlet 5 for separating the feeding belt 4 and the original document and surely feeding one sheet.

The feeding belt 4 is provided with an opening 11 of an air intake duct 12 which is hung from above at its intermediate portion.
The intake duct 12 is connected to a fan device 13 and forms an air flow in the direction of the arrow. That is, air suction is performed.

The air outlet 5 has a plurality of air blowing nozzles (not shown) for blowing the end portion of the front surface of the sheet original in order to separate the bundle of placed sheet originals. The air outlet 5 is connected to the fan device 15 via the exhaust duct 14 and forms an air flow in the direction of the arrow. These devices constitute the air ejection means.

As shown in the perspective view of FIG. 3, the feeding belt 4 is constructed by winding a plurality of endless belts 17 around a driving roller 16a and a driven roller 16b at a predetermined interval. The endless belt 17 is formed with a number of vent holes 18 which are inserted in the thickness direction in a dispersed manner, and the sheet original 1 is sucked through the intake duct 12 from the opening 12 through the vent holes 18 and the like. Adsorb.

Although the sheet feeding apparatus shown in FIG. 1 is illustrated as an example of feeding the sheet original 1, an apparatus for feeding the sheet paper other than the sheet original to the above-mentioned transfer position for image formation. Can be applied as is. That is, the transport path 6 is configured as a transport path reaching the transfer position.

In the sheet feeding apparatus for originals configured as described above, the uppermost sheet on the loading tray 2 is held at a fixed position. Therefore, according to the present invention, the sheet original 1 placed on the original placing tray 2 is opposed to
A means for detecting the position up to the top of the sheet is provided. As shown in FIG. 1, this position detecting means detects the distance to the uppermost portion of the placed sheet original 1,
The distance measuring sensor 20 is arranged so as to face the sheet original to be placed, and the uppermost surface of the sheet is irradiated with light.
The reflected light is received by the light receiving means, and the distance from the sensor 20 to the uppermost portion is measured under this light receiving condition. By measuring this distance, the positional relationship between the uppermost sheet document and the transport belt 17 of the feeding belt 4 can be determined. Therefore, it is possible to determine whether or not the uppermost position of the sheet document is in an appropriate state, and the sheet document 1 attracted to the feeding belt 4 is reliably fed.

Therefore, based on the distance measurement sensor 20, the air discharge and suction operations for the feeding belt 4 and other feedings are started in a state where the measured distance is constant, and the feeding is performed in accordance with the feeding instruction. Start sending operation. In this case, the position of the uppermost sheet can be directly measured by the distance measuring sensor 20 and can be held at the specified position. That is, until the distance measured by the distance measuring sensor 20 detects a predetermined distance (specified position), the drive motor connected to the lifting mechanism is drive-controlled, and in response to the specified position detection, Stops driving the drive motor. In particular, the distance measuring sensor 20
However, if a long distance is detected with respect to the specified position (reference distance), it is determined that the rising position is insufficient, and the drive motor is rotated in the forward direction. On the other hand, if a short distance is detected with respect to the reference distance, the drive motor is rotated in the opposite direction, and the loading tray 2 is lowered, because the distance is too high. In this way, by controlling the raising and lowering of the loading tray 2, the uppermost portion of the loaded sheet can be held at a predetermined position.

Further, when the uppermost portion of the seat is further raised from the specified position by the inertial force of the drive motor, if the raised position at that time is a position where there is no problem due to suction by air suction, it is held as it is, If this raised position is a problem, reverse driving for lowering can be performed. In addition, in order to correct the influence of the inertial force in the up-and-down drive, the drive motor is stopped before the reference distance is detected, and the correction is performed to hold the stopped uppermost sheet position at the specified position. You can do it. This is because the distance measuring sensor 20 can always measure the distance. Moreover, in the correction of the reference distance, the setting condition of the sheet document, for example, the mounting amount can be detected by the distance measuring sensor 20, so that the reference distance can be corrected according to the detection condition. That is, if the mounting amount is small, the degree of increase due to the inertial force tends to be large, and if the mounting amount is large, the inertial force is less affected and the increase is suppressed.
Therefore, it is possible to determine a correction value according to the mounting amount (number of stacked sheets, etc.).

In short, since the distance measuring sensor 20 can grasp its state from the distance between the sensor and the lowermost portion of the seat, it is possible to easily control the drive motor related to the lifting mechanism based on the distance, and to perform accurate measurement. Position control can be ensured. Although the details of the distance measuring sensor 20 will be described later, the distance measuring sensor 20 includes an infrared light emitting element 21.
And a light receiving element 22 for receiving the reflected light from the original, and the output to the light receiving element 22 is calculated by calculating the distance through a signal processing circuit.

Next, FIG. 4 shows a control system of the sheet feeding apparatus according to the present invention. The control system will be described with reference to FIG.

As shown in FIG. 4, the control system is a microcomputer 40 including a master CPU as control means.
Is equipped with. The master CPU 40 receives signals from various keys and sensors according to a program previously stored in the ROM 41, and controls the copying operation and the document feeding operation by the RDH 30. Further, the RAM 42 for storing the data required each time the control is performed is a ROM
41 are connected in the same manner. The RAM 42 is provided with a backup power supply 43 in order to hold the stored contents.

Further, the master CPU 40 controls the supply and stop of the supply of voltage to the copy lamp 45 of the optical system through the copy lamp drive circuit 44 and the application to the copy lamp 45 in order to execute the copy control operation. Adjust the execution voltage level. In addition, the master CPU 40
Performs a series of copy control via various drive circuits including the voltage supplied to the charging device, the developing device, the transfer device, the cleaning device, the static eliminator, and the like as necessary.

Further, the master CPU 40 receives the signal related to the measurement from the distance measuring sensor 20 according to the present invention via the signal processing circuit 46, and the loading tray 2
The drive motor 48 connected to the elevating mechanism is driven and controlled, and the drive motor (not shown) of the feeding belt 4 which is a feeding means corresponding to the driving motor 48 is separated, and the document is separated and one sheet is fed. The drive control of a drive motor (not shown) that controls the discharge amount of the fan device 15 for forming the flow of air from the blow-out port 5 is performed. Further, the CPU 40
Fan device 1 constituting suction means of the feeding belt 4
The drive control is performed also including a suction drive motor (not shown) that drives the motor 3.

The distance measuring sensor 20 has a light emitting element 21 for measuring the distance. Therefore, the master CPU 40 drives the light emitting element 21 at a predetermined timing in order to measure the distance of the distance measuring sensor 20.
The signal is output via the signal processing circuit 46, and the drive motor 48 is driven according to the reception status. To control. In this case, normal rotation drive for raising the loading tray, reverse rotation drive for lowering, and stop control are performed.

Further, in the CPU 40, copy conditions, for example, a numerical key for numerically inputting the number of copies, a copy magnification,
An operation panel 50 having an input key for specifying various functions such as copy density, double-sided or composite copy, trimming and masking, and a display unit for displaying the contents of the above-mentioned input copy conditions is connected. Copy control is executed in response to an input made with the keys on the operation panel, and at the same time, a reference distance indicating the height of the uppermost sheet according to the present invention and a necessary minimum or upper limit distance are input. Used to do. This point will be described in detail in the description of the embodiment.

The operation of the copying apparatus having the above structure will be described.

The copy original 1 is placed, for example, with the image side facing up, in the original placing tray 2 when copying is performed using the RDH 30, for example. Switch this mounting state to switch 3
To detect. In this case, the loading tray 2 is the detection switch 1
At 9, the state existing at the bottom is detected. Therefore, when the above-described setting work is completed, the CPU 40 inputs the detection signal of the detection switch 3 to drive the drive motor 48, particularly to drive it upward. This may be started when the copy start switch (copy button) is operated.

As described above, at the same time when the raising drive of the mounting tray 2 is started, the distance measurement by the distance measuring sensor 20 is started. The measured signal is sent through the signal processing circuit 46 to the analog input terminal AN1, of the CPU 40.
The data is input to AN2, and the CPU 40 calculates the distance L according to the input situation. It is determined how the measured distance L is with respect to the reference distance Lo. Therefore, when the measurement distance L becomes equal to the reference distance Lo, the ascending drive of the drive motor 48 is stopped.

When the above driving is completed, air is blown from the air outlet 5 to suck air, and then the feeding belt 4 is driven to start feeding the uppermost sheet original 1. To be done. In this case, the top sheet document 1
Since the feeding is started in a state where it is held at a fixed height which is the specified position, the separating operation by the blowing of air and the suction to the conveyor belt 4 by the air suction are surely performed, and thus one sheet is fed. You can ensure delivery.

Here, in FIG. 1, the uppermost sheet original 2
At the position, the reference prescribed Lo, which is a prescribed position where the separation and the suction operation are surely performed, is shown, and this position Lo is the distance from the distance measuring sensor 20 to the lifted uppermost portion of the sheet. This specified position is the center within the range where one sheet can be fed, and the upper and lower limits are shown as L ₁ and L ₂ with respect to the reference distance. This distance is within a range where reliable feeding can be performed at the reference distance, and when the uppermost sheet exists within this range, the lifting drive control is not performed.

It is considered that the reference position Lo, the upper limit position L ₁ and the lower limit position L ₂ are different in the sheet feeding device. Therefore, in order to store a value peculiar to each device in advance, the value is input in advance by using the copy number input key on the operation panel 50, and the RAM 42 is stored.
Keep it in memory.

Therefore, although the reference distance, the upper limit, and the lower limit are slightly different depending on the blowing amount and the sucking amount of air, the sheet feeding device assembled in the manufacturing process or the like with the air flow rate fixed. Can be actually driven to obtain an appropriate position, which can be stored.

When the sheet originals shown in FIG. 2 are cyclically fed, the original placing amount, that is, the distance from the upper surface of the placing tray to the uppermost portion of the placed sheet, excludes the original being fed. It is always constant, and once the top position is set as the reference position, the top position does not change. Therefore, the position may be fixed after the feeding is started.

When circulating the original document, the position of the uppermost original document is maintained at a substantially prescribed position as described above, but when sequentially feeding sheets such as recording paper,
The position of the uppermost sheet lowers with each feeding because it decreases with each feeding. Therefore, the position of the uppermost sheet is raised to the specified position. This is the distance measuring sensor 20.
To detect the position of the uppermost sheet. If the lower limit position L ₂ is not reached (the measured distance becomes longer), the drive motor 48 is driven upward, and the drive motor 48 is stopped when the reference position Lo is reached. The position of the upper sheet can always be maintained at the specified position.

Here, when setting the sheet, the loading tray 2 is lowered by the lifting mechanism, that is, the drive motor 4 is set.
8 is driven downward (reverse rotation drive), and the detection switch 19 detects it and stops the drive. As a result, the sheet document or the like is set and the ascending drive is performed.
At this time, the distance measurement sensor 20 can determine the amount of sheets set on the uppermost tray 2 to be placed. As the sheet amount, the weight of the entire sheet bundle to be placed or the sheet bundle can be detected as the stacking amount (number of sheets, etc.). This means that when the distance from the sensor 20 is large, the loaded amount is small, that is, the weight or the loaded amount is small.

Therefore, when the inertial force of the drive motor 48 becomes a problem, the uppermost sheet position can be controlled and held at the reference position by correcting the reference distance Lo in the ascending drive after setting the sheet. That is, when the load amount is small, the distance measuring sensor 20 measures a long distance. Therefore, the correction amount is increased and a value obtained by adding the correction amount from the reference position Lo is set as the correction reference distance Lo ′. When the distance measuring sensor 20 detects a distance corresponding to the distance Lo ', the driving motor 48 is stopped, so that the uppermost sheet can be stopped in a state where the uppermost sheet reaches the reference distance Lo due to inertial force. become. Therefore, a more accurate correction can be achieved by setting a correction amount and correcting the reference distance Lo based on the load amount or the like according to the distance measured by the distance measuring sensor 20.

Further, the number of sheets or the like can be grasped and displayed according to the measured distance at this time. In order to display the number of sheets, while the copying machine is on standby, the loading tray 2 is lowered to the lowermost position, and the uppermost position of the sheet is measured in this state, so that the remaining number of sheets can be grasped and displayed. . Also, when setting sheets, the number of sheets can be similarly grasped by distance measurement.

Next, one specific example of the distance measurement by the distance measuring sensor 20 of the present invention will be described in detail. This distance measuring sensor 20 is disclosed, for example, in "Sensor Technology", Vol. 11 uses the “8-bit precision distance measuring sensor” described on pages 24 to 27. This distance measuring sensor is a PSD (Position Sensitive).
It is called a Deector sensor, which irradiates light from a light emitting element onto an object to be measured, and measures the distance by the incident position of the reflected light from the object to be measured on the sensor.

This distance measuring sensor will be briefly described. This is a kind of PIN type photodiode, and as shown in FIG. 5, the silicon chip has ap ⁻ layer on the front surface, an n ⁺ layer on the back surface, and an intermediate layer therebetween. It is composed of an i layer, and electrodes A, B and C as shown in the figure are provided on the respective layers on the front surface and the back surface. 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 depending on the incident position (spot position) of the light on the light receiving surface of the PSD sensor.
1 and I2, and the current ratio I1 / I at this time
2 is, for example, proportional to the distance from the electrode B (inversely proportional to the distance from the electrode A). At this time, although the absolute values of the currents I1 and I2 change depending on the amount of light incident on the PSD sensor, since the incident position of light is proportional to the current ratio I1 / I2, the amount of light itself has no effect.

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, thus enabling accurate distance detection. In particular, when the current ratio becomes large, the incident light comes closer to 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, a light emitting element (infrared LED) 21 constituting the distance measuring sensor 20 of the present invention.
Is emitted to the object to be measured (the uppermost sheet original), and the reflected light is transmitted through the light receiving lens to the distance measuring sensor 2
The light receiving portion 22 of the PSD sensor that constitutes 0 is caused to receive light.
The position x1 of the light receiving point (spot) at this time is obtained by x1 = A · f / L1 in the relationship shown in the figure. In the above formula, A is the center distance between the light projecting lens and the light receiving lens, L1 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 PSD sensor becomes smaller and the position moves to the position x2 as the distance to the object to be measured 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.

The point x on the light receiving surface of the PSD sensor is the current ratio I1 / I2 obtained from the electrodes A and B as described above.
Therefore, the distance D from the light emitting element 21 to the object to be measured, that is, the distance to the light receiving portion 22 of the distance measuring sensor 20 can be easily measured according to the above equation.

Therefore, in the present invention, as shown in FIG. 4, currents I1 and I2 obtained from the PSD sensor, which is the distance measuring sensor 20, are applied to the voltage V1 by the signal processing circuit 51.
And V2 and input via the analog port input section of the master CPU 40. Here, the signal processing circuit 51
Is to be converted into a voltage value equivalent to or equal to the obtained currents I1 and I2. Master CPU 4
0 calculates the value corresponding to I1 / I2 on the basis of this voltage value to obtain the spot position (x) of the distance measuring sensor 20. The distance L can be calculated.

Therefore, if necessary, the master CPU 4
0 outputs a signal for driving the driver 49 to cause the light emitting element 21, which is an infrared LED, to emit light. Further, based on the output from the light receiving element 22 of the distance sensor 20, the drive control of the drive motor 48 that drives the lifting mechanism according to the obtained distance is executed.

Some control examples of the feeding means according to the distance measurement of the distance measuring sensor 20 according to the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 8 is a flowchart showing an example in which a sheet original is placed on the original placing tray 2 and the feeding control is performed based on the sheet original.

When the sheet originals 1 are set, they are stacked and placed on the original placing tray 2 with the image side facing up. In this placement, the placement tray 2 is lowered to the lowermost position, and this state is detected by the detection switch 19.
If the sheet original 2 is placed, this placed state is
It is detected by a document detection switch 3 provided at an appropriate position on the document placing tray 2. When a series of copies according to the set number of originals is completed, the original placing tray 2 is lowered to the lowermost position. Alternatively, when the top of the sheet is maintained at the prescribed position, it is detected that the document has been removed and the document is lowered.

When the sheet original 1 is set as described above, the raising operation is started. Here, as for the loading tray 2, when setting the sheet originals, the loading tray 2 may not be lowered to the lowermost position but may be stopped in a state where the copying operation by the previous sheet bundle of originals is performed. . That is,
The position of the loading tray 2 when the original is copied on the loading tray 2 shown in FIG. 1 and the original is removed is held. When the sheet document 2 is placed in this state, the detection switch 3 detects it.

When the print switch or the like is operated, the control flow shown in FIG. 8 is executed. From the above, if at least the state that the document is placed on the tray 2 is detected by the detection switch 3 (n0), the measurement operation by the distance measurement sensor 20 is executed (n1).

In step n1, the distance to the uppermost sheet document 1 placed is measured. The distance measuring sensor 20 for measuring the distance measures the distance L from the distance sensor 20 to the placed uppermost sheet document 1 by driving the light emitting element 21. As described above, this is because the master CPU 40 inputs the voltage V1 / V2 corresponding to I1 / I2 from the distance measurement sensor 20 to the analog input terminal, and the top sheet original 1 which is the object to be measured.
Find the distance L to.

When this distance L is obtained, the CPU 40
Is, for example, when the measurement distance L is within the range of the standard prescribed Lo (L ₂
<L <L ₁ ) or otherwise (n2, n3). As described above, this reference distance Lo corresponds to the position (regulated position) at the center of the proper inner space where the feeding belt 4 can surely adsorb. The lower limit position L ₂ and the upper limit position L ₁ including the reference distance Lo, which is the specified position, are preliminarily input by the input keys on the operation panel 50 and stored in the storage means as peculiar to the sheet feeding apparatus. This storage is stored in a predetermined area such as the RAM 42 and is held by the backup power supply. This value is input, for example, by a numerical value input key on the operation panel 50 after the assembly is completed and stored.

Therefore, in the above determination, the measurement distance L
Is larger than the lower limit distance L ₂ within an appropriate range, that is, when the distance from the sensor to the uppermost portion of the sheet is long, the CPU 40 determines that the position of the uppermost portion of the sheet exists at a position lower than the reference prescribed Lo of the prescribed position. A rising drive command is output to the drive motor 48 (n4). As a result, the motor drive device 47 drives the drive motor 48 in the forward rotation direction. Then, the loading tray 2 is raised, and in this raising process, the distance measuring sensor 20 measures the distance to the uppermost sheet of the rising sheet (n5) each time. The measurement distance L and the distance distance Lo are compared (n6). As a result, the drive motor 48 continues to be driven (n6 → n4 → n5) until the raised position reaches the reference distance Lo, and if the uppermost portion rises to the specified position, the drive motor 48 is driven at n7.
Stop driving.

The first measured distance L is the upper limit position L ₁
When the distance is smaller, that is, when the distance from the sensor 20 to the uppermost portion is short and is smaller than the upper limit position L ₁ , it is determined that the position of the uppermost portion of the seat is considerably higher than the reference distance Lo, and the CPU 40 controls the driving motor 48. The descending drive command is output (n8). As a result, the motor drive circuit 49
Drives the drive motor 48 in reverse. Then, the loading tray 2 is lowered, and in the lowering process, the distance measuring sensor 20 measures the distance to the uppermost sheet being lowered (n9) each time. This measurement distance L is the reference distance L
The relationship with respect to o is compared in n10. Based on the comparison result, the descending drive of the loading tray 2 is continued (n10 → n8 → n9) until the reference distance Lo is reached. The distance measuring sensor 20 indicates that the uppermost position of the loading tray 2 has reached the reference distance Lo, which is the specified position.
Is detected, the drive of the drive motor 48 is stopped by n7.

As described above, the uppermost position of the sheet original 1 set on the placing tray 2 is maintained within the proper range (L _{1 to} L ₂ ) based on the standard prescribed Lo. Here, after the above control is terminated and the process returns to step n1, the distance measurement sensor 20 again measures the distance. This distance L
However, in steps n2 and n3, if it is not within the range of the lower limit position L ₂ and the upper limit position L ₁ , the above-mentioned operation is executed again, but if it is within that range, the flow shown in FIG. The CPU 40 executes the feeding start operation.

Here, each time one sheet original 1 is fed, the number of sheet originals on the tray 2 decreases. But,
In the case of the RDH 30, the fed sheet original 1 is returned from the lowermost part of the placing tray 2 after the image processing is completed. Therefore, once the uppermost position is set to the specified position before the start of feeding, the position becomes substantially constant, and thereafter, the lifting mechanism control of the loading tray 2 is not performed. At this time, although only the sheet original being fed is reduced, this reduction is set within an appropriate range.

The above is the description of the operation relating to the feeding control by the sheet original 2. However, if the sheet is fed to the image forming position, the sheet is gradually reduced and the uppermost position is changed. Will be reduced. Therefore, in the case where the sheet is gradually reduced by being fed, the uppermost position is always kept within the range of the reference distance Lo by executing the flow shown in FIG. 8 each time even during the feeding operation. Yes, stable feeding is possible.

Further, in the lifting control of the loading tray 2 described above, the inertial force when the rotation of the drive motor 48 is stopped is not taken into consideration. However, if there is a problem with the inertial force, it can be said that correcting it is a useful control.

This inertial force has many problems when the loading tray 2 is first raised. In other words, the driving time when the sheet is set and the ascending drive is very long. In particular, when the loading tray 2 is lifted and the uppermost sheet is held in the prescribed position, when the upper tray is driven to rise every time the number of sheets decreases, the driving time is very short and the stop driving is performed before the constant speed driving. The inertial force does not matter so much. However, in the first ascending drive, the drive is stopped in the state of being driven at a constant speed, and therefore, the position slightly rises from the stop-controlled position. This is also true when descending. But,
In the case of the method of feeding the sheet onto the loading tray 2 from above, the sheet is rarely set with the loading tray 2 in the uppermost state. That is, the feeding means is located above the placed sheet, and the placed sheet is restricted.

Therefore, it is a general operation to raise the loading tray 2 after loading the sheets. Therefore,
The distance measurement sensor 20 detects the position of the uppermost sheet placed, that is, the distance is measured and the amount of the placed sheet is
For example, grasp the number of sheets. This is because the measurement distance and the number of sheets are proportional to each other if the thickness of the sheet is constant, so that the accurate number can be grasped.

The inertial force during ascent depends on the number of sheets measured. For example, when the weight of the placed sheet is heavy, the rise is small due to the inertial force of the drive motor 48, and when the weight of the placed sheet is light, the increase amount is smaller than the inertial force of the drive motor 48. growing. for that reason,
When the distance measured by the distance measuring sensor 20 is long, the number of sheets to be placed is small and the placing weight on the placing tray 2 is light. At this time, the correction amount is set large. That is, even if the stop control is performed at the reference distance due to the problem of inertial force, the raising amount of the loading tray 2 is large, and the reference distance Lo is added to correct the raising amount (correction amount) Δ1 corresponding to this. , Correction reference distance L
o ′ (Lo + Δl) is obtained, and this distance is measured by the sensor 20.
The drive of the drive motor 18 is stopped at the timing detected by. As a result, the reference distance L that is the regular specified position
The top can be positioned at o.

The detection of the placement amount for the above correction is performed when the placement tray 2 is placed. In particular, it is performed in advance before the ascending drive. Further, if a problem occurs in the inertial force of the drive motor 48 even in the first descent drive, Lo-Δl may be obtained as the correction of the reference distance Lo contrary to the above. However, in many cases, this is not driven downward in the first drive as described above.

Here, the number of sheets to be placed can be grasped by measuring the distance to the uppermost sheet to be placed while the placing tray 2 is present at the bottom. As described above, there is a fixed relationship between the measurement distance and the number of sheets to be placed. The longer the measurement distance, the smaller the number of sheets to be placed, and the shorter the measurement distance, the larger the number of sheets to be placed. Therefore, if the thickness of the sheet is constant, the number of sheets can be measured according to the measurement distance. This allows the number of sheets to be measured when the detection switch 19 detects that the loading tray 2 is descending to the bottom. Therefore, by displaying the measured number of sheets on the display device, it is convenient because the user can be notified and it can be easily judged whether or not the number of sheets is sufficient before copying.

On the other hand, in addition to the above-described correction of the reference distance, the correction amount control shown in FIG. 9 is performed by raising or lowering the inertia of the drive motor 48 regardless of the amount placed on the placing tray 2. An example of correction when there is a problem in force is shown.
That is, the present invention is applied to the case where the drive motor 48 has a constant rotational drive force regardless of the mounting weight.

Therefore, the correction mode is set before the lifting drive for starting the feeding. This mode setting may be performed using a mode setting key provided on the operation panel 50, but it may be performed during standby before copying start of the copying apparatus or during warm-up of the copying apparatus after power-on. it can.

When the above-mentioned correction mode is set, first, the driving for raising the stopped loading tray 2 is executed (s1). At the same time, the distance measuring sensor 2
The distance measurement by 0 is executed (s2), the measured distance L and the reference distance Lo are compared (s3), and the measured distance L is Lo.
If it is above, the ascending drive control is continued. Then, when the reference distance Lo is increased, the driving of the drive mode 48, that is, the ascending drive is stopped.

After that, the timer T is started (s5), and after the processing time of the timer T has elapsed (s6), the distance measurement sensor 20 again measures the distance (s7). The timer T is set to the time from when the driving mode 48 is stopped and driven until the rotation is completely stopped. The distance measurement is performed by the distance measurement sensor 20 after the elapse of the timer time in order to grasp the amount of increase due to the inertial force after the driving mode 48 is stopped.

Therefore, the previously stored reference distance Lo is read (s8), and the relationship between the measured distance L and the reference distance Lo is determined. That is, the reference distance L
We ask how much it has risen with respect to o. This is for obtaining the correction amount Δl, and is calculated by Δl = Lo-L. This correction amount Δl is increased by the inertial force after the rotation of the drive motor 48 is stopped. In consideration of the increase amount, the correction reference distance Lo ′ is obtained as Lo + Δl, and this value is calculated next time, for example, in the next feed. It is used to control the raising and lowering of the loading tray 2 related to the feeding operation. That is, the correction reference distance Lo 'is read out and the control shown in FIG. 8 is performed. This corrected reference distance Lo 'is read during the ascending drive and is used to stop the drive of the ascending-drive motor 48. Further, as the correction when the descent driving is performed, the above-mentioned Δl may be subtracted from the reference distance Lo, and the corrected reference distance Lo ′ = Lo−Δl at the descent driving may be obtained and stored.

Whether or not the correction reference distance Lo 'is appropriate is determined by
After storing the correction reference distance Lo 'for confirmation, the loading tray 2 is lowered to the lowermost position, stopped by the detection of the detection switch 19, and the control shown in FIG. 9 is executed from that state. At this time, with respect to the timing of stopping the drive motor 48, in step s3, the corrected reference distance Lo 'is compared with the measured distance L. Then, the drive of the motor is stopped before the reference position Lo is detected, and after the time of the timer T has elapsed, the distance measurement by the distance measurement sensor 20 is performed.
The measurement distance L and the reference distance Lo are compared.

At this time, if the reference distance Lo is substantially the same, it is determined that the correction is normal, and this correction reference distance L
Fix o '. However, when they do not match, the difference (Lo-L) between the reference distance Lo and the measured distance L is obtained, and this difference is added as a further correction value for the above-mentioned corrected reference distance Lo '. In this case, when the measured distance L is larger, it means that the degree of increase is small, and the difference is added from the correction reference position Lo ′, and the result is subtracted and stored as a new correction reference distance Lo ′. Let More accurate positioning can be performed by performing the above-described confirmation at the time of ascending drive at the obtained correction reference distance (corrected specified position) until the uppermost portion is positioned at the reference distance Lo.

For this correction, stop control of the drive motor 48 is performed with reference to the reference distance Lo, and the degree of increase due to this is measured. However, the drive motor 48
Is performed, and the distance is measured at the time when the driving is stopped at an arbitrary position, and the distance is measured again after a certain time in order to grasp the amount of movement due to the inertial force with respect to the measured distance L. The difference (L-L ') with L'is the correction value (Δl)
You can also ask. This correction value may be added during ascending driving and subtracted during descending driving.

The setting of the mode of the correction reference distance Lo 'is not limited to when the power is turned on, and for example, the loading tray 2 may be provided so as to be pulled out from the apparatus main body when setting sheet paper. This is to facilitate the operation of setting the sheet paper on the loading tray 2. In this case, a drawer detection switch (not shown) for confirming the drawer state is provided. Therefore, this detection switch detects the pull-out state of the loading tray 2 (O
FF), and after adding the sheet paper to the mounting tray 2 or changing the set paper, when it is mounted on the apparatus main body, the detection switch detects (ON). By detecting this state, the loading tray 2 is driven to move up. By utilizing this, the correction mode can be set and the control shown in FIG. 9 can be executed. By this execution, the correction reference distance that becomes the specified position can be obtained and stored, and the position of the uppermost sheet is held at the position of the reference distance Lo of the specified position. Therefore, it is not necessary to set the time for the special correction mode, and the time can be effectively used.

(Second Embodiment) In this embodiment, a self-diagnosis based on the lifting operation of the loading tray 2 including the drive motor 48 is executed by using the distance measuring sensor 20. It is to save the trouble and the configuration for setting the special mode of the self-diagnosis of the drive motor 48.

FIG. 10 shows a flowchart of control for that purpose. This flow can be easily executed by using the distance measuring sensor 20 in the course of the control operation for performing the elevation drive.

In this embodiment, what is particularly noteworthy is that the self-diagnosis can be executed each time the feeding operation is started. In particular, in FIG. 8, the distance (La) measured by the distance measuring sensor 20 in step n1 is temporarily stored, and when n2 → n4 → n5 → n6 → n2 ascending drive is executed or n3 → n8 → n9 → n10. → It can be performed when the descent drive of n3 is executed.

Therefore, when the ascending or descending drive is performed in FIG. 10, the distance (La) by the distance measuring sensor 20 is temporarily stored (n11, n12). Then, the timer T1 is started, and after a lapse of the timer T1, the distance measuring sensor 20 is driven again to measure the distance (n13, n14, n15, n16). The timer T1
Is for driving the driving motor 48 for a certain period of time to detect the degree of movement corresponding to the driving time at that time. That is, by driving the driving motor 48 for a certain period of time (T1), the moving amount of the mounting tray moving up and down shows a constant value (A) unless there is another factor that hinders the movement.

Therefore, after a fixed time (T1), the ascending / descending distance is measured by the distance measuring sensor 20 and the measured distance (Lb) is temporarily stored in an area different from the above-mentioned measured distance (La) (n18). For this storage, a predetermined area of the RAM 42 is allocated and stored.

Then, at n19, with respect to the amount of rise (A) of the loading tray 2 after being driven for a certain time, the previously measured distance (La)
Is smaller than the difference (ΔL) from the measured distance (Lb) after a certain time, it is determined that the state of the raising / lowering operation is bad, that is, the vertical movement by the raising / lowering mechanism is bad, and the driving of the drive motor 48 is stopped (n20). The trouble is displayed (n21). At this time, the copying operation is stopped at the same time. That is,
If the absolute value of the measurement distances La-Lb is smaller than the movement amount (A) that will rise after a certain period of time, there is an abnormality in the mechanism for moving up and down and its drive system, and before the copying operation is started. You will be able to self-diagnose.

At this time, it is possible to self-diagnose that the elevator mechanism and the drive motor 48 are abnormal, and at the same time, the apparatus is stopped. By diagnosing this failure, the drive motor 4
It is possible to determine whether the rotation of No. 8 is abnormal or the lifting mechanism itself is abnormal. In this case, it is possible to determine whether the motor rotation is abnormal or not by performing the self-diagnosis of the drive motor 48 as in the conventional case. Therefore, if there is no abnormality in the motor 48 itself, it can be determined that there is a failure (trouble) due to the elevating mechanism that enables the loading tray 2 to move up and down.

On the other hand, if the ascending / descending state is normal, the distance (Lb) measured after a certain period of time in order to continue the self-diagnosis while the drive motor 48 is being driven up or down.
Is stored in the area where the previously measured distance (La) is stored, the timer T1 is started again, and the above-described operation is repeated after a fixed time. This allows the self-diagnosis flow of FIG. 10 to be performed before the top of the loading tray 2 is positioned at the reference distance Lo and is stopped.

As the self-diagnosis, the flow shown in FIG. 10 is executed not only during the ascending or descending drive, but also during the operation of performing the ascending or descending drive during standby to measure the correction amount and the number of loaded sheets. You may let me. In other words, it is not necessary to execute a special mode for self-diagnosis, and it can be executed during the ascending or descending drive, so that unnecessary time can be eliminated.

In each of the above embodiments, the position of the uppermost portion of the placed sheet paper (original) is recognized based on the distance measurement by the distance measurement sensor 20, and the PSD sensor is used as the sensor. , But not limited to
The present invention can be implemented by any means that can be detected as a distance.

Further, as the arrangement position of the distance measuring sensor 20, in FIG. 1, it is arranged at a position facing the rear end position of the portion opposite to the front end in the feeding direction of the placed document. This is not limited to that position, and it may be arranged at a position where it does not interfere with the feeding by the feeding means and does not interfere with the loading of the sheet. A space between them may be used to be provided at that position so as to face the mounting sheet.

Here, according to the above-described embodiment, the case where the air feeding means by the feeding belt and the suction means is provided as the feeding means has been described as an example, but this feeding means uses the friction roller. Even things are used as they are.

That is, the feeding roller is pressed against the uppermost sheet and the feeding roller is rotationally driven to perform feeding. Also in this case, since the position of the uppermost sheet is always held at the predetermined position, the feeding force becomes constant during feeding, and the feeding is stable. This feeding force is determined by the pressing force and friction between the feeding roller and the sheet. For example, when the feeding roller is forcibly pressed to the uppermost sheet by its own weight or vertically moved, Although the pressing force changes greatly depending on the uppermost position, the uppermost sheet can be positioned at a predetermined defined position at all times, so that the pressing force can be made substantially constant for feeding.

[0118]

According to the sheet feeding apparatus of the present invention, it is possible to raise and lower the placing tray by using the raising and lowering mechanism and accurately hold the uppermost position to be placed at the predetermined reference position. Especially, since the uppermost position can be grasped and the elevation control can be performed, the position can be accurately regulated. Therefore, the feeding operation can be stabilized.

Further, since the self-diagnosis of the elevating mechanism and the like can be executed during the elevating control, the self-diagnosis mode is not separately set and the operation and driving means therefor can be omitted.
Labor saving becomes possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing an example of a sheet feeding apparatus of the present invention.

FIG. 2 is a schematic cross-sectional view showing a state in which the sheet feeding device of the present invention is mounted on a circulation type document feeder (RDH) of a copying machine.

FIG. 3 is a perspective view showing an example of a sheet feeding unit that constitutes the sheet feeding apparatus.

FIG. 4 is a block diagram showing a control system of a copying control apparatus including control of a sheet feeding apparatus according to the present invention.

FIG. 5 is a PSD showing an example of the distance measuring sensor of the present invention.
Sectional drawing of a sensor.

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

FIG. 7 is a schematic diagram illustrating the principle of distance measurement.

FIG. 8 is a control flowchart showing an example of sheet feeding control according to the present invention.

FIG. 9 is a flowchart of control for correcting a specified position in sheet feeding control according to the present invention.

FIG. 10 is a control flowchart for self-diagnosis of a lifting mechanism and a drive motor in the sheet feeding apparatus of the present invention.

FIG. 11 is a cross-sectional view for positioning the uppermost portion by a conventional lifting mechanism in the sheet feeding device.

[Explanation of symbols]

1 sheet original (or sheet paper) 2 sheet loading tray 3 sheet presence / absence detection switch 4 feeding belt 20 distance measuring sensor (PSD sensor) 21 light emitting element 22 light receiving element 30 recirculating document feeder (RDH) 40 master CPU 46 signal Processor (processing circuit for distance measurement) 48 Drive motor for raising and lowering loading tray Lo Reference distance (specified position) L ₁ , L ₂ Range of specified position

Claims (6)

[Claims] 1. A loading tray for loading a sheet cut to a predetermined length and vertically moved via an elevating mechanism, and feeding a sheet on the loading tray to a predetermined position. A sheet feeding device comprising a feeding means for feeding and a driving means for driving the elevating mechanism to raise and lower the placing tray for holding the uppermost sheet on the placing tray at a prescribed position. The position detecting means for detecting the height up to the uppermost part placed on the placing tray, and the driving means is controlled based on the position detection by the position detecting means. A sheet feeding device comprising: a control unit that moves the uppermost portion to a specified position. 2. The sheet feeding apparatus according to claim 1, wherein the position detecting means is composed of a distance measuring sensor for measuring a distance to the uppermost sheet. 3. The control means controls the elevation of the drive means based on a comparison between a reference distance applied to the prescribed position and a distance measured by the distance measuring sensor in order to hold the uppermost portion of the seat at the prescribed position. The sheet feeding device according to claim 2, wherein the uppermost portion of the sheet is moved to a specified position. 4. The sheet feeding apparatus according to claim 3, wherein a reference distance applied to a prescribed position of the uppermost portion of the sheet is inputted by a key input means as needed and stored. 5. The control means, when performing up-and-down drive control of the drive means based on the stored reference distance, measures the distance measured by the distance measuring sensor and the reference distance after stopping the drive means based on the reference distance. 5. The sheet feeding device according to claim 4, wherein a difference between the above-mentioned values is obtained, and the difference is used as a correction value of the reference distance as a movement amount due to the inertial force of the driving means, and the subsequent lifting control is performed based on this value. . 6. A placing tray for placing a sheet cut to a predetermined length and vertically movable via an elevating mechanism, and a sheet on the placing tray is fed to a predetermined position. In the sheet feeding device, which is provided with a feeding means for feeding, and a driving means for driving the elevating mechanism to raise and lower the placing tray to hold the uppermost sheet on the placing tray at a prescribed position, The distance measuring means for measuring the distance to the uppermost sheet on the placing tray, and the driving means based on the distance measured by the distance measuring means are used to control the uppermost sheet on the placing tray. A control means for moving to a prescribed position, and while the above-mentioned tray is being moved up and down by the control means, the distance measuring means measures the distance to the top of the sheet, and when the measured distance does not change after a certain time, Above Sheet feeding apparatus comprising: the diagnostic means for self-diagnosis, as trouble means.