JPH0713393A - Sheet feeding condition controlling device - Google Patents

Abstract

PURPOSE:To control a feeding condition according to a mounting amount of documents under the optimum condition, to prevent a feeding error previously, and to surely carry out feeding. CONSTITUTION:When documents 1 are mounted on a document tray 2, this mounting condition is detected by a detection switch 3. On the basis of this detection, a distance from a sensor to the uppermost part of the mounted documents, in other words, the amount of the mounted documents is detected by a distance measuring sensor 20 above the document tray 2. When the detected amount of the documents is more than the maximum mounted amount on the document tray 2, driving of a feeding belt 4 is forbidden, while driving of the feeding belt 4 is allowed when the detected document amount is the maximum mounted amount or less. The number of revolutions of a motor driving a fan device 13 is controlled so as to control an air volume according to the document amount, and the mounted document air separation based on the control of an air flow rate and feeding of one piece of the document is surely carried out at the same time.

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 into a predetermined size to a predetermined position, for example, a sheet feeding device for feeding a sheet original or the like to a reading position. In particular, it relates to feeding control of the sheet.

[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. As described above, there is a recirculating document handler (hereinafter referred to as RDH) that returns the sheet document from the document placing tray to the exposure position and from the exposure position to the document placing tray.

Further, in addition to feeding the sheet original, according to the image forming apparatus, in order to transfer an image formed on a photoconductor, which is a recording medium, particularly a toner image, to a sheet paper,
A sheet feeding device for feeding the sheet of paper to the transfer position is provided. As this sheet feeding device,
Besides using a friction roller, for example, Japanese Patent Laid-Open No. 60-825.
As described in Japanese Patent Publication No. 37, No. 37, there is one that feeds a sheet of paper placed on a placing tray by air means, that is, air blowing and air suction.

As described above, the image forming apparatus is equipped with a device for feeding sheet originals and a feeding device for feeding sheet papers, and automatically feeds them as needed.

[0007]

When the original is fed to a predetermined position, the original is placed on the original tray, and the amount of the original placed is predetermined. In other words, the amount of the originals that can be placed on the original tray (the number of sheets to be placed) is determined by the feeding capacity of the feeding means, or when copying on both sides or the same side (composite copying). The sheets are stored in the intermediate tray, and the processing capacity is determined by the ability to store the sheets in the intermediate tray.

Therefore, when a sheet original is placed on the original placing tray and an amount of original that cannot be fed is placed,
Document feeding failure may occur due to insufficient capacity of feeding means,
The copying machine stops halfway due to a paper transport trouble in the intermediate tray.

In order to prevent this, for example, Japanese Patent Laid-Open No. 59-59
In Japanese Laid-Open Patent Publication No. 7647 and Japanese Utility Model Laid-Open No. 63-59157, it is detected that a document placed on the document tray exceeds a predetermined amount, and the operation of the feeding unit is prohibited based on this detection. is doing.

Further, in the case where the cut sheet is separated by air suction or air blowing as the feeding means, and the cut sheet is air-fed through a suction belt or the like, the amount of the original document on the original document tray is Regardless of the reason, the air is always fed with a constant amount of air, so that feeding failure is inevitable. Therefore, in the past, it has been disclosed in JP-A-60-
As disclosed in Japanese Patent No. 82537, it is clarified that the air flow rate is controlled according to the amount of paper placed. In this case, the air flow rate is controlled depending on whether or not the paper is a predetermined amount or more. It's just an alternative. Therefore, it is not possible to perform detailed control according to the amount of documents,
The probability of defective feeding increases due to problems with the air flow rate.

Moreover, according to Japanese Patent Laid-Open No. 59-7647 and Japanese Utility Model Laid-Open No. 63-59157, the feeding operation is simply prohibited when the number of sheets to be placed exceeds a predetermined amount. Further, according to Japanese Patent Laid-Open No. 60-82537, the air flow rate is simply selected depending on whether or not it exceeds a predetermined amount, and there is no way to control the air flow rate according to the mounting amount. Therefore, conventionally, based on the detection of whether or not a predetermined amount is exceeded, the flow rate of air according to the sheet loading amount can be controlled by simply controlling the feeding operation or controlling the air flow rate to a single value. Cannot be controlled.

In view of the above problems, the present invention detects the amount of sheets, for example, a document, placed on the placing tray to control the sheet feeding according to the amount of the placed sheets, thereby causing a feeding failure. It is an object of the present invention to provide a sheet feeding control device that eliminates the above-mentioned problem and, at the same time, drives the air flow rate in an optimum state to enable reliable air feeding.

[0013]

According to another aspect of the present invention, there is provided a sheet feeding control device for feeding a sheet tray on which a sheet original is placed and an original on the placing tray to a predetermined position. A sheet feeding device including a sheet feeding unit including an air unit, and a sheet amount detecting unit that detects the amount of sheets placed on the placing tray, and a sheet by the placing amount detecting unit. A control unit configured to control the air flow rate of the feeding unit according to the mounting amount.

A sheet feeding control device according to a second aspect of the present invention is the sheet feeding control device according to the first aspect, which stores in advance a processable sheet amount capable of processing the sheet placed by the feeding means, Comparison means for comparing the stored data of the storage means with the sheet placement amount detected by the placement amount detection means, and the control means based on the comparison result of the comparison means,
The feeding means is set to an operable state or a non-operating state, and in the operable state, the air flow rate is controlled according to the sheet mounting amount of the mounting amount detecting means.

A sheet feeding control device according to a third aspect of the present invention is the sheet feeding control device according to the first aspect, wherein the feeding means feeds the sheet document on the loading tray to a predetermined position and then returns it to the loading tray. It is characterized in that it is a document circulating and conveying means.

A sheet feeding control device according to a fourth aspect of the present invention is the sheet feeding control device according to the first aspect, wherein the sheet feeding control device faces the sheet to be placed, as a sheet amount detection means for detecting the amount of the sheet placed on the sheet tray. A distance measuring sensor including a light emitting element and a light receiving element provided in the same manner, and the amount of seating of the sheet is detected by measuring the distance between the sensor and the top of the placed sheet. To do.

A sheet feeding control device according to a fifth aspect of the present invention includes a loading tray on which cut sheets are loaded, and air means for feeding the sheets on the loading tray to a predetermined position. In a sheet feeding device including a feeding unit, a distance to the uppermost portion of the placed sheet is set in order to detect the amount of the sheet placed on the placing tray, which includes light emitting and light receiving elements. In response to the non-detection signal of the distance measuring sensor for measuring, the sheet detecting means for detecting the presence or absence of the sheet placed on the above-mentioned tray, the sheet detecting means,
Performs self-diagnosis related to the distance measurement of the distance measurement sensor, and controls the air amount of the feeding means according to the sheet amount measured by the distance measurement sensor when the self-diagnosis is normal. A control means for driving and controlling the feeding means in a standard state irrespective of detection of the sheet amount by the distance measuring sensor.

A sheet feeding control device according to a sixth aspect of the present invention is the device according to the fifth aspect, further comprising a storage means for storing in advance a processable sheet amount capable of processing the sheet on which the feeding means is placed. The control means inhibits the feeding operation of the feeding means when the distance measuring sensor detects a placed sheet that exceeds the sheet amount stored in the storage means.

According to a seventh aspect of the present invention, in the sheet feeding control device according to the first or fifth aspect, the distance measuring sensor also serves as a sensor for detecting the presence / absence of a sheet placed on the placing tray. Is characterized by.

[0020]

According to the apparatus of the first aspect of the present invention, when the sheet is placed on the placing tray, the placement amount of the placed sheet is detected by the placement amount detecting means. The flow rate of air is controlled according to the detected sheet amount. For example, the flow rate of air is increased when the mounting amount is large, and the air flow rate is decreased when the mounting amount is small. This ensures that the stacked sheets are separated, and the feeding means
It is possible to reliably feed the sheets.

Further, according to the apparatus of the second aspect of the present invention, if the amount of sheets to be placed on the placing tray is equal to or more than a predetermined amount, feeding failure or the like may occur. Therefore, the maximum mounting amount is stored in advance in the storage means. By comparing the stored content of the storage unit with the detected sheet placement amount, the comparison unit outputs a detection result indicating whether or not the stored content is equal to or more than the stored content. Based on the comparison result, the control means sets the feeding operation of the feeding means to the operating or non-operating state. Therefore, if the operating state is set, the air flow rate is controlled according to the sheet mounting amount. This enables stable feeding. On the other hand, when the detected sheet placement amount is larger (larger) than the content of the storage unit, the feeding unit is set to the non-operating state, and the sheet placement amount is notified as exceeding the feeding processing capacity, for example, It is possible to display and instruct the user to reduce the amount of sheets to be fed.

Further, according to the apparatus of the third aspect of the present invention, since the document is fed to a predetermined position and then circulated again to the document tray, the placement amount of the document is being fed. Except for originals, a fixed amount of originals are always placed, so you can detect the amount of paper placed before the start of feeding and fix the air amount based on this to ensure more stable feeding, especially circulating feeding. It is possible and easy to control.

According to the apparatus of the fourth aspect of the present invention, in order to detect the amount of the placed sheet, the distance measuring sensor is used to determine the amount of the placed sheet depending on the distance between the sensor and the placed uppermost sheet. The amount of the formed sheet can be easily detected. Therefore, according to the detection, it is possible to measure the distance according to the number of sheets to be placed, and thus it is possible to perform finer feeding control.
In other words, by gradually reducing the number of fed sheet documents,
It is possible to detect the decreasing remaining amount of the sheet and perform the feeding control according to the detected condition. In particular, the air flow rate of the air means can be finely controlled.

Further, according to the apparatus of claim 5 of the present invention, the mounting amount can be accurately detected by self-diagnosing the mounting amount detecting means, and the air flow rate for feeding based on the detection can be determined. You can control. Moreover, if the placement detection means fails as a result of the self-diagnosis, the feeding means is not controlled based on the detection state of the placement detection means, and the standard air flow rate according to the capability of the feeding means is achieved. Can be set and controlled. This allows
Stable feeding control can be performed without reckless control.

According to the sixth aspect of the present invention, in the fifth aspect, when the sheet placement amount exceeds the processing capacity of the sheet feeding means as a result of the self-diagnosis, the sheet feeding operation is prohibited. . As a result, defective feeding can be prevented.

Further, according to the apparatus of claim 7 of the present invention, the presence or absence of the sheet placed on the placing tray can be determined by the distance measuring sensor based on the distance measurement. If there is a document as a result of this distance measurement, the distance is processed as the document placement amount, and the operation of the apparatus according to claim 1 is executed.

[0027]

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, it is needless to say that the present invention can be applied not only to the image forming apparatus but also to a facsimile or the like in an apparatus for feeding one sheet of a transmission document to the reading position.

FIG. 1 is a sectional view showing a specific example of a sheet feeding control device of the present invention applied to a copying machine, and FIG. 2 shows an example of applying the sheet feeding control device to a document circulation feeding device (RDH). FIG.

In FIG. 2, the copying apparatus is provided with an original circulating device (RDH) 30 having an original placing tray for placing sheet originals on the upper part of the main body of the copying apparatus.

The sheet-shaped original 1 is placed on the original placing tray 2. An operation piece of a micro switch 3 for detecting the presence / absence of an original placed on the original placing tray is located on the original placing tray 2, and the micro switch 3 is attached to the original placing tray 2. The operation piece is pushed down by the placed document to operate, and the presence of the document is detected.

On the originals placed on the original placing tray 2, there is arranged a feeding belt 4 which is a feeding means for sequentially feeding the uppermost originals. A part of suction means is incorporated in the feeding belt 4, and the uppermost original 1 is sucked onto the belt by air suction, and the sheet original is fed by the movement of the belt. Along with the feeding belt 4 which is the feeding means, the stacked originals placed on the original placing tray 2 are separated into individual sheets, and air is fed in front of the originals (feeding sheet) in order to reliably feed one sheet. An air outlet 5 is provided for blowing out from the front (in the feeding direction). The uppermost one of the originals 1 separated by the air blowing from the air outlet 5 is adsorbed to the feeding belt 4 by the suction means, and the belt 4 is rotated in the arrow direction, so that the original 1 Carry out.

The fed document 1 is fed along a transport path 6 formed by a guide plate, and is sequentially transported by various transport rollers 7 arranged in the transport path. An exposure unit 8 for projecting an image of the document 1 on the surface of a photosensitive drum, which is a recording medium that is rotatably driven and is provided in the main body of the copying apparatus, is disposed in the middle of the conveyance 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. A 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 1 which has passed through the exposure section 8 is further conveyed via the conveying rollers 7c, returned to the lower part of the original tray 1 and again circulated and conveyed. When the original document shown in FIG. 1 is circulated and conveyed, the upper and lower surfaces of the original document 1 are inverted and returned to the original document tray 1. Therefore, when the original document 1 is a double-sided original document, the original document is read at 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 reversing it 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 schematic configuration of the RDH 30 including the feeding device. A copying apparatus main body (not shown) is located below the RDH 30. That is, the copying apparatus main body is provided with an optical system for irradiating the transparent plate 9 constituting the exposure unit 8 with light and projecting it onto the photosensitive drum surface. This optical system consists of a copy lamp such as a halogen lamp,
It is equipped with a plurality of mirrors, a zoom lens, etc., and projects the image of the document 1 conveyed to the transparent plate onto the photosensitive drum.

A photosensitive drum formed in a drum shape is rotatably arranged below the optical system. 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 a further image is formed on the sheet of paper on which the image is formed, for example, when an image is formed again on the opposite side of the sheet of paper on which the image is formed, the sheet of paper is temporarily discharged to the intermediate tray without being discharged. The sheet is conveyed, and the sheet is again fed from the intermediate tray to the transfer position.

As described above, in order to expose the image on the photosensitive drum, it is necessary to feed the original 1 placed on the original placing tray 2 by the feeding belt 4 and feed it to the exposure section 8. is there. Therefore, FIG. 1 shows the details of the structure of the air outlet 5 in order to separate the feeding belt 4 and the original and surely feed one sheet.

The feeding belt 4 has an opening 12 of an air intake duct 11 which is hung from above in the middle thereof.
The intake duct 11 is connected to the fan device 13, and forms a flow of air in the arrow direction. That is, air suction is performed.

The air outlet 5 blows the front surface of the original document and the front end portion of the original document attracted to the feeding belt 4 in order to separate the placed original document bundle. The air outlet 5 composed of this nozzle is connected to the fan device 15 through the exhaust duct 14 and forms an air flow in the direction of the arrow.

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 large number of vent holes 18 that are inserted in the thickness direction in a dispersed manner, and the document 1 is adsorbed by the suction force of the intake duct 11 through the vent holes 18 and the like.

In the sheet feeding apparatus of the original configured as described above, the feeding belt 4 and the outlet 5 which are the feeding means are controlled to feed the original 1 placed on the original placing tray 2. Ensure stable and stable delivery. Therefore, according to the present invention, a means for detecting the placement amount (original amount) of the document 1 placed on the document placing tray 2 is provided. As shown in FIG. 1, the sheet placement amount detecting means of the original document is composed of a distance measuring sensor 20 placed and arranged so as to face the original document. The original surface is irradiated with light and the reflected light thereof is received by the light receiving means. The light is received at, and the distance from the sensor 20 to the document surface is measured under this light receiving condition. By measuring this distance, the amount of documents corresponding to the number of documents can be determined. That is, since the distance between the uppermost portion and the distance measuring sensor 20 changes according to the number of originals, the amount of originals that is the amount placed on the placing tray 2 by measuring the distance. Can be detected.

Therefore, the operation of the feeding belt 4 is controlled according to the mounting amount corresponding to the measured distance based on the distance measuring sensor 20, and the flow rate of air is also controlled.

In the distance measuring sensor 20, the distance between the sensor and the uppermost portion of the placed document determines the number of placed sheets (when the thickness of the sheet to be used is constant). Accordingly, the number of placed sheets, that is, the amount of documents can be detected. For details of the distance measuring sensor 20,
As will be described later, the distance measuring sensor 20 includes an infrared light emitting element 21 and a light receiving element 22 that receives the reflected light from the document, and outputs the light to the light receiving element 22 via a signal processing circuit to calculate the distance. Obtained by processing.

Next, the control system of the document sheet feeding apparatus configured as shown in FIG. 4 will be described with reference to FIG.

As shown in FIG. 4, the control system has a microcomputer 40 including a master CPU as a 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.

For example, the master CPU 40 controls the supply and stop of the voltage supply to the copy lamp of the optical system via the copy lamp lighting circuit 42, and adjusts the execution voltage level applied to the copy lamp 43. Further, the master CPU 40 controls the voltage supplied to the charging device, the developing device, the transfer device, the cleaning device, the static eliminator and the like through various drive circuits as necessary.

Further, the master CPU 40 receives a signal relating to the measurement from the distance measuring sensor 20 according to the present invention through the signal processing circuit 50, and drives the feeding belt 4 which is a feeding means according to the signal. The motor 44 and
The speed control circuit 46 is instructed to the rotation speed of the blow-out drive motor 45 of the fan unit 15 for forming the air flow from the blow-out port 5 for separating the document and feeding one sheet. As a result, the speed control circuit 46 controls the rotation speed via the driver 47.

The CPU 40 also controls the drive including the suction drive motor 48 for driving the fan unit 13 which constitutes the suction means of the feeding belt 4. Therefore, a speed command signal is sent to the rotation speed control circuit 49, and the rotation speed of the motor 48 is controlled according to the speed command.

The distance measuring sensor 20 has a light emitting element 21 for measuring the distance. Therefore, the master CPU 40 causes the light emitting element 21 to be driven by the driver 5 at a predetermined timing in order to measure the distance of the distance measuring sensor 20.
0, and the signal output according to the light receiving state of the distance measuring sensor 20 at this time is received via the signal processing circuit 51, and based on this, drive control of the sheet feeding belt 4 or blowing is performed. The rotation speed of the drive motor 45 at the outlet 5 is controlled.

The motors 45 and 48 are driven by the speed control circuits 46 and 49 which receive the speed command signal from the CPU 40, and the rotary encoder 53 via the drivers 47 and 52.
Based on the outputs of 54 and 54, drive control is performed at a speed according to the measurement command. In order to control this rotation speed, the rotation speed of the motor can be easily controlled by controlling the voltage supplied to the motor or by controlling the frequency that determines the rotation speed of the motor.

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. Therefore, when the copy start switch (copy button) is operated, the CPU 40 receives the command and starts the copying operation. Before starting this copying operation, the CPU 40 drives the distance measuring sensor 20 in order to detect the amount of the document placed.

Therefore, the light emitting member 2 of the distance measuring sensor 20.
The light from 1 is received by the light receiving member 22 through the original,
When the CPU 40 inputs a signal based on the light receiving condition via the signal processing circuit 51, the distance between the sensor 20 and the uppermost portion of the placed document is calculated and obtained. This measured distance is processed as a document placement amount, that is, a document amount, and it is determined whether or not the document amount can be fed by the feeding belt 4. That is, it is stored in advance in a predetermined area of the RAM 55 or the ROM 41, which is a storage unit, whether or not the placed document exceeds the feedable amount (specified value). The stored specified value is compared with the detected document amount, and when the detected document amount exceeds the specified value, the feeding belt 4
Driving is prohibited. That is, the drive of the drive motor 44 is prohibited. Then, the CPU 40 notifies that the placed document exceeds the specified value. As this notification, the display lamp is turned on, or a character display device or the like is arranged on the operation panel unit so that the user can be notified by a message such as "document placement over" on this display device.

On the other hand, when an original document having a prescribed value or less is placed on the original document tray 2, the CPU 40 permits the drive motor 44 of the feeding belt 4 to be driven, and the driver 56 is issued by the paper feed command. And start the feeding operation via
The copying machine main body side also starts the paper feeding to start the copying operation. At this time, the CPU 40 sets the rotation speed of the blow-off drive motor 45 in order to control the amount of air blown out from the blow-out port 5 in accordance with the detected document amount, and outputs this speed command to the speed control circuit 46. This allows
The air flow rate from the air outlet 5 is controlled according to the amount of the original. In this case, the rotation speed of the motor is controlled so that the air amount is increased when the original amount is large, and the air amount is decreased when the original amount is small.

When the feeding is started, the original 1 is adsorbed to the feeding belt 4 by the suction means from the uppermost portion and is fed to the conveying path 6, and is exposed at the exposing section 8 in the middle of the conveying path.
An original image is formed on the photosensitive drum by the action of the optical system. The original document 1 that has passed through the exposure unit is returned to the original document tray 1 via the transport roller 7c.

When the originals are circulated and fed as described above, the amount of the originals is constant except for the originals being fed, and the amount of the originals is detected in advance before the copying operation is started. It is possible to control by fixing the air flow rate based on the original amount. As a result, control is simplified and stable separation and one sheet feeding can be reliably performed.

It should be noted that, instead of the RDH 30 for feeding the sheet original, the original is fed to the exposure section and the exposed original is fed to the original discharge tray arranged separately from the original tray before the start of feeding. In the automatic document feeder (ADF), the document amount is reduced every time the document is fed. Therefore, the reduced state can be driven by the distance measuring sensor 20 as required, and the rotation speed (rotation speed) of the motor 46 can be controlled based on the measured distance in order to control the amount of air blown out.

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 below. This is a kind of PIN type photodiode, and as shown in FIG. 5, there is ap ⁻ layer on the front surface of the silicon chip, an n ⁺ layer on the back surface thereof, 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. 4 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 50 to cause the light emitting element 22 which is an infrared LED to emit light. Further, based on the output from the distance sensor 20, the obtained distance is processed as the amount of the original document, and the drive control of the feeding belt 4 as the feeding means or the flow rate of the air blown from the air outlet 5 is controlled. A speed command for controlling the rotation speed of the blowing motor is output to the rotation control circuit. In this case, the air amount of the suction means of the feeding belt 4 can also be controlled.

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 flow chart showing an example in which an original is placed on the original placing tray 2 and the feeding means is controlled based on the amount of the placed original.

The original is placed on the original tray 2 with the image side facing up.
It is loaded on top. When this placement state is detected by the document detection switch 3 provided at an appropriate position on the document placement tray 2 (step n1), the CPU 40 instructs the distance measurement sensor 20 to start the distance measurement. That is, the distance measuring sensor 20
By driving the light emitting element 21 of the
Is irradiated to the uppermost part of the light receiving part 22 and the reflected light is received by the light receiving part 22.

Therefore, by driving the light emitting element 21,
The distance L from the distance sensor 20 to the uppermost part of the placed document can be measured. As described above, this means that the voltage V1 / V2 corresponding to I1 / I2 from the sensor 20 is applied to the master CP.
By inputting by U40, the distance L to the uppermost original 1 which is the object to be measured is obtained (n2).

When this distance L is obtained, the CPU 40
Determines (n3) whether the measured distance L is less than or equal to the specified distance LO, for example. As described above, the specified distance LO is a specified value corresponding to the maximum number of originals that can be processed by the feeding device, and this distance is stored in the storage unit in advance. . This storage is stored in a predetermined area such as the ROM 41 or the RAM 55. In this case, if there is no problem with the placement amount in the feeding device, such storage is not necessary, and the air flow rate control described below may be executed based on the placement amount of the document.

Therefore, when the sheet processing capacity of the sheet feeding device is not influenced by the amount of sheets placed, the copy switch C is executed in step n4 without performing the control in step n3.
Check whether the SW has been operated. When the copy switch is operated in this confirmation, the air flow rate blown out from the air outlet 5 is controlled to separate the stacked sheet originals according to the sheet placement amount detected by the switch n2 (n
5) is done. That is, as shown in FIG. 12, the number of rotations of the drive motor 45 of the fan unit 13 for controlling the air flow rate is set according to the amount of the placed document (the amount of the document), and the signal of the set number of rotations, That is, a pulse frequency or the like that determines the voltage or the rotation speed is set, and this is set to the speed control circuit 46.
Supply to.

As a result, the speed control circuit 46 supplies the motor 45 with a voltage in accordance with the command of the number of revolutions thereof to control the speed at that number of revolutions. At this time, the encoder 53
The speed control circuit 46 inputs a signal relating to the number of rotations from the motor 45, so that the motor 45 can be held and controlled at the set number of rotations.

As described above, the flow rate of air is determined according to the amount of sheet originals on the placing tray 2, and the air is blown to the front side of the placed originals with the flow rate according to the placing amount. Separate the stack of originals. In this state, the operation of the feeding belt 4 is started (n6), and the separated uppermost sheet document 1 is a fan unit 13 as a suction means.
Drive motor 58 and drive belt 4 drive motor 4
At the same time when the copying machine main body side starts feeding by adsorbing to the feeding belt 4 by the suction force of the action of 4, the copying apparatus main body side controls various members involved in image formation and starts copying operation (n7). To do.

On the other hand, when the feeding device has a feeding ability, a specified value based on the maximum loading amount according to the ability is stored in the storage means. Therefore, as described above, in step n3, the measured distance L is compared with the storage distance LO that is a prestored specified value, and if the measured distance L is less than or equal to the storage distance LO, a copy start command is issued to the CPU 40. When the operation state of the copy switch CSW is confirmed (n4) due to the output of the above, the air flow rate control and the feeding belt drive are performed as described above, and at the same time, the copy control operation is started.

Therefore, when the measured distance L exceeds the storage distance LO that cannot be fed, the driving of the drive motor 44 for the feeding belt 4 is prohibited. This prohibits driving (n8) together with the suction means. Then, it is displayed that the placed document 1 exceeds the specified amount (n
9) Let it do.

As described above, the original is placed on the placing tray 2 and
When copying, it is not necessary for the user to count the number of originals one by one in advance and to judge whether or not it can be processed by this, just by placing it, the suitability is automatically determined and the feeding operation is performed. By controlling whether or not to perform, it is possible to prevent feeding failure and miscopy in advance.

Further, although the measured distance is used as it is as the number of originals, it may be converted into the number of sheets (placed amount) based on the comparison table of the distance and the number of sheets, and processed by this. In this, as shown in FIG. 11, the output from the distance measuring sensor 20 is converted into the mounting amount (number of sheets) according to the output of the voltage ratio output via the signal processing means 51.

The timing for detecting the amount of the placed document is set when the detection switch 3 for detecting the placement of the document is operated. However, not limited to this, in response to the operation of the copy switch, step n
The document amount detection operation based on 2 is performed after the confirmation in step n4, and steps n5 and n5 are performed according to the placed amount of the sheet document.
n6 may be sequentially executed. In addition, when the mounting amount is limited, after the mounting amount is detected, the stored amount may be compared with the specified value, and the drive control in step n5 or n8 may be performed according to the comparison result.

Therefore, even if the copy switch is operated, if the stacking amount is limited, and if the number of sheet originals is larger than the specified amount, the driving of the feeding belt 4 is prohibited in step n8. At the same time, the large amount of placed documents can be left unattended, erroneous copying and document feeding failure can be prevented, and start of the copy operation can be prohibited.

Alternatively, since the flow rate of air is controlled according to the amount of the sheet original 1 placed, the feeding belt 4 is used to
It is possible to reliably feed the sheets.

(Second Embodiment) In this embodiment, the failure of the distance measuring sensor 20 itself is discriminated by self-diagnosis, and the amount of the placed document is determined while the distance measurement is normally executed. While detecting and performing control based on this, driving in the standard state for driving the feeding means is executed by failure diagnosis regardless of detection of the document placement amount.

The flow for that is shown in FIG. In this flow, the same parts as those in FIG. 8 are designated by the same reference numerals, and the description thereof will be omitted.

In this embodiment, it should be noted that the distance measuring sensor 20 is self-diagnosed when the feeding operation is not performed, that is, the document 1 is not placed on the document placing tray 2. It is a point.

Therefore, when the document detection switch 3 detects that the document is not placed on the document tray 2,
Moving to step n11, distance measurement is executed. That is,
The distance measuring sensor 20 is driven to start the distance measurement. The measurement target at this time is the document placing tray 2 itself, and the distance between the document tray 2 and the distance measuring sensor 20 maintains a constant distance Ls. That is, the distance measuring sensor 20 is fixed at a predetermined position, and the distance from the document placing tray 2 is constant.

In this case, as shown in FIG. 13, the sensor 20 receives the reflected light from the reflection plate 23 provided under the opening 2-1 provided in the mounting tray 2, and this distance Ls is obtained.
You may clean it. Since the reflection plate 23 is arranged below the surface of the tray 2, the distance L when one sheet original is placed and the constant distance Ls can be clearly distinguished, and accurate detection can be performed. .

Therefore, this distance Ls is stored in advance in the storage means such as the ROM 41 or the RAM 55 as described above. As a result of the distance measurement by the distance measurement sensor 20, the relationship between the distance L and the constant distance Ls is compared in step n12. At this time, when the measured distance L is substantially equal to the constant distance Ls (including a certain tolerance), the distance measuring sensor 20 is assumed to be operating normally, and the document 1 is placed on the document tray 2. Wait (return to n1).

If the measured distance L is not the constant distance Ls, it is displayed that the distance measuring sensor is out of order (n1).
3) Let it go. At this time, the operation of the copying apparatus may be prohibited.

However, even if the distance measuring sensor 20 fails, if the copying apparatus main body and the RDH 30 itself do not fail, the feeding belt 4 can be driven to feed the original, and thus the required copy can be made. Can be done. Therefore, the standard state where the driving of the feeding belt 4 is allowed and the control of the flow rate of the air is not controlled by the amount of the placed document but the proper feeding operation can be performed by the feeding means as in the conventional case. Set the amount of air blown in
The motor 45 may be controlled based on this.

Therefore, the failure of the distance measuring sensor 20 is displayed in step n13 of FIG. 9, and the above-described control is executed in steps n14 to n18 without stopping the operation. Further, as the feeding device, there is a feeding operation, for example, a flow rate of air or the like in a proper state by the feeding device.
This can be experimentally obtained after manufacturing, etc., and the appropriate feeding control value (S) in the standard state is stored in advance.

Therefore, after step n13, it is confirmed that the switch 1 detects that the original 1 is placed on the original tray 2 (n14) and that the copy switch is operated. By performing (n15), the copy operation is started. At this time, before the feeding belt 4 is driven, the flow rate of the air blown from the outlet 5 is controlled in the standard state (S) as described above.

That is, in step n16, the rotation speed of the motor 45 for controlling the flow rate of the air blown out from the outlet 5 is set in the speed control circuit 46 as the speed (S) in the standard state. As a result, the motor 45 rotates at the standard speed, and the air flow rate corresponding to the rotation is supplied to the air outlet 5
Blow out. After that, drive the feeding belt 4 (n17)
And the copy operation is started (n18).

Therefore, the air blowing amount is not controlled by the incorrect measurement data based on the distance measuring sensor 20, but is controlled by being fixed to the air blowing amount in the standard state by the feeding means. It is possible to prevent reckless control and to feed manuscripts in proper condition.

Also in the present embodiment, if the capacity that the feeding device can process does not depend on the amount placed on the placing tray 2, steps n3 and n8, n are performed.
The control of 9 should be omitted. However, when the capacity that the feeding device can process is determined by the amount to be placed on the placing tray 2, control may be performed according to the flow shown in FIGS. 9 and 10.

(Other Embodiments) According to the example described above, the detection state of the document 1 placed on the document tray 2 is detected by providing the detection switch 3 separately on the tray. The measurement sensor 20 can be used in common.

As a means for this, as shown in FIG. 13, an opening 2-1 is provided at a position corresponding to the distance measuring sensor 20 of the document tray 2, and light from the sensor is provided in the opening 2-1. A member that blocks reflection, for example, a black-painted light absorbing member (23) is arranged, or a hollow state is set so that light is not reflected, or even if it is reflected, the back surface of the document tray 2 (original document tray). It is configured to be reflected on the surface opposite to the placing surface). Alternatively, the reflection plate 23 is provided in the lower portion of the opening 2-1 and the light from the reflection plate 23 is used for the distance measurement sensor 2
You may make it make 0 receive light. In this case, the reflection plate 23 is naturally located below the surface of the document tray 2.

As a result, when the document is not placed on the tray 2, the distance measurement sensor 20 determines that the reflected light of the object to be measured is not received and the distance measurement is impossible.
Alternatively, by receiving the light from the reflecting plate, the distance to the reflecting plate 23 is measured, and it is determined whether or not the measured distance L exceeds the distance (Ls) to the document placing tray 2. It can detect that there is no document.

On the other hand, when the document is placed on the document tray 2, the distance L between the sensor 20 and the top of the document is measured by the reflected light from the document. As a result, it can be detected that the document is placed.

For example, as shown in FIG. 10, distance measurement is performed by the distance measurement sensor 20 as needed. In this case, as described above, the opening 2- formed in the document placing tray 2
The reflection plate 23 is arranged below the unit 1. Therefore, in step n20, distance measurement is performed. Measurement distance L at this time
Is determined to be equal to or greater than the distance (Ls) to the document placing tray 2 (n21). In this determination, the measurement distance is L
If it exceeds s, it is determined that the sheet is not placed, and the display (n22) is performed, and the sheet document is waited to be placed.

At this time, if it is determined that the measured distance L is equal to the distance Lx from the sensor 20 to the reflector 23, the distance measurement of the distance measurement sensor 20 is normal, that is, there is no abnormality as a result of self-diagnosis. It is also possible to wait for a state in which a sheet is placed on the original document tray 2 to be placed.

When a sheet original is placed on the placing tray 2, the distance L measured in step n20 is
It is smaller than the distance Ls to the document placing tray 2. Therefore, the presence of the document is detected by the determination in step n21, and this is displayed (n23). As a result, the control after step n3 shown in FIGS. 8 and 9 is executed. By measuring the distance with the distance measuring sensor 20, not only the presence / absence of the document placed on the document placing tray 2 but also the self-diagnosis of the distance measuring sensor 20 itself is executed.

With regard to this self-diagnosis, if the distance measurement in step n20 is performed when the power of the copying machine is turned on, the sheet original is not placed on the placing tray 2. Therefore, the self-diagnosis is performed after step n22. Can diagnose. This is when the distance measuring sensor 20 can measure the distance to the object to be measured. Therefore, when the distance cannot be measured, the CPU 40 determines that there is a failure at step n20. If a failure diagnosis is made as a result of the accident diagnosis, the control after step 13 in FIG. 9 is executed.

Therefore, since the distance measuring sensor 20 can be used as the sheet placement detecting means of the document placing tray 2 without separately providing the microswitch 3, the detection switch is not required and the switch is arranged. Space can be saved and cost can be reduced.

As described above, the number of placed documents is detected based on the distance measurement by the distance measurement sensor 20, and the PSD sensor is used as the sensor.
Without being limited to this, the present invention can be implemented as long as it can be detected as a distance.

Further, as the arrangement position of the distance measuring sensor 20, in FIG. 1, the distance measuring sensor 20 is arranged so as to face the rear end of the original tray 2 opposite to the front end in the feeding direction of the original to be placed. This is because when a document is adsorbed and fed from the tip, the distance between the document adsorbed and the sensor 20 may be measured if the document is provided at the tip. In other words, according to the document feeding device that feeds the document to the exposure unit and then discharges it to the document discharge unit different from the document tray without circulating the document, the loading amount is reduced. This is a problem when the amount of air blown out is detected by the sensor 20. Therefore, when the original is sucked and fed, it is desirable to dispose the original so as to face the rear end of the original, as shown in FIG.

Here, in the case of circulating feeding from the document tray to the exposure section and then to the document tray again, the document on the document tray always has a constant document placement amount except for the document being fed. Therefore, as for the distance measuring sensor 20, in the distance measurement, before the copying operation is started, especially before the feeding operation is started, the mounting amount can be measured, and the blowing amount of air according to the mounting amount can be fixed. . That is, the placement amount of the original does not change except for the original being fed. for that reason,
The distance measuring sensor 20 may be arranged between the belts of the feeding belt 4 as its arrangement position. With such an arrangement, the operation of placing the original placed on the original tray 2 becomes easy without being disturbed by the sensor 20.

In this case, even if the carrier is not circulated,
At the timing before the sheet is attracted to the feeding belt 4,
If the measurement is performed by the distance measuring sensor 20, the sensor can be provided on the feeding belt 4.

Further, in the present invention, when the original is fed, the feeding from the uppermost part of the original has been described as an example, but as described in JP-A-60-82537, Of course, the present invention can be applied to a document which is sequentially fed from the lowermost manuscript, and has the same effect. In addition, JP-A-60-
Although the paper feeding is described in Japanese Patent No. 82537, it can also be used as an RDH as shown in FIG. That is, it is configured such that the lowermost one of the placed documents is sequentially fed and the used document is returned to the uppermost one. With such a configuration, it is possible to detect the amount of the placed document and control the drive of the feeding unit or the flow rate of air according to the detected amount of the document.

Moreover, the present invention can be directly applied to not only the sheet original feeding but also the sheet paper feeding apparatus for feeding the paper for image formation.

[0110]

According to the sheet feeding apparatus of the present invention, the feeding means is driven and controlled in accordance with the amount of the sheet placed on the tray for feeding the sheet. When more than 5 sheets are placed, the feeding operation can be prohibited in advance to prevent feeding failure.

Further, when the air means is used as the feeding means, the flow rate of the air can be controlled according to the mounted amount, so that the single sheet feeding can be reliably performed with stable feeding.

Furthermore, as the means for detecting the amount of paper placed,
Since the sensor that can measure the distance can accurately grasp the amount of placement, more precise feeding control can be performed.

In particular, in the self-diagnosis of the sensor and the failure detection, the drive control in the standard state of the feeding device is performed without prohibiting the feeding, the feeding control based on the sensor, and the reckless operation. A reliable and stable feeding operation can be performed without performing a feeding control.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part showing an example of a sheet feeding control device of the present invention.

FIG. 2 is a schematic cross-sectional view in which the sheet feeding device of the present invention is applied to 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 relating to control of the sheet feeding apparatus of the present invention.

FIG. 5 is a P showing an example of a distance measuring sensor according to the present invention.
Sectional drawing of SD sensor.

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

FIG. 7 is a diagram for explaining 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 control flowchart showing an example of self-diagnosis of the distance measuring sensor according to the sheet feeding control according to the present invention.

FIG. 10 is a control flowchart showing an example in which the distance measuring sensor also detects the sheet mounting state according to the sheet feeding control according to the present invention.

FIG. 11 is a characteristic diagram showing the relationship between the output related to distance measurement of the present invention and the number of documents.

FIG. 12 is a characteristic diagram showing the relationship with the rotation speed of the motor for controlling the air flow rate based on the measured distance of the present invention.

FIG. 13 is a cross-sectional view showing an example in which the distance measuring sensor of the present invention is also used for detecting the presence or absence of a document.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 sheet original 2 original placing tray 4 feeding belt 4 5 air outlet 13 fan device for suction means 15 fan device for air blowing 20 distance measuring sensor (PSD sensor) 21 light emitting element (infrared light emitting LED) 22 light receiving element 23 Reflector (for detecting presence / absence of original) 30 Circulating original conveying device (RDH) 40 Master CPU 44 Motor for feeding belt drive 45 Drive motor for air blowing 46 Speed control circuit 48 Drive motor for air suction 49 Speed control circuit

Claims (7)

[Claims] 1. A sheet feeding apparatus comprising: a placing tray for placing sheet originals; and feeding means including an air means for feeding the originals on the placing tray to a predetermined position. Placement amount detection means for detecting the amount of sheets placed on the placement tray, and control for controlling the air flow rate of the feeding means according to the sheet placement amount by the placement amount detection means A sheet feeding control device comprising: 2. The sheet feeding control device according to claim 1, wherein the sheet feeding control device stores in advance a processable sheet amount capable of processing the sheet placed by the sheet feeding means, storage data of the storage means and the sheet loading position. Comparing means for comparing the amount of seated sheets detected by the quantity detecting means, and the control means sets the feeding means to an operable state or a non-operating state based on the comparison result of the comparing means. At the same time, in an operable state, the sheet feeding control device is controlled to an air flow rate according to the sheet placement amount of the placement amount detection means. 3. The document circulating / conveying device according to claim 1, wherein the feeding unit is a document circulating / conveying unit that feeds the sheet document on the loading tray to a predetermined position and then returns it to the loading tray. Sheet feeding control device. 4. A mounting amount detecting means for detecting a mounting amount of a sheet on a mounting tray comprises a distance measuring sensor including a light emitting element and a light receiving element provided facing a sheet to be mounted, 2. The sheet feeding control device according to claim 1, wherein the sheet loading amount is detected by measuring a distance between the sensor and an uppermost portion of the loaded sheet. 5. A sheet feeding device comprising: a placing tray for placing a cut sheet; It consists of a light emitting element and a light receiving element, and in order to detect the amount of sheets placed on the above-mentioned tray, the distance measurement sensor that measures the distance to the top of the placed sheet and the one placed on the above tray. Sheet detection means for detecting the presence or absence of a sheet to be detected, and self-diagnosis related to distance measurement of the distance measurement sensor in response to a non-detection signal of the sheet detection means While controlling to the air amount of the feeding means according to the sheet amount measured in
A sheet feeding control device comprising: a control unit configured to drive and control the feeding unit in a standard state irrespective of detection of the sheet amount by the distance measuring sensor when a failure occurs due to self-diagnosis. 6. The sheet feeding control device according to claim 5, further comprising a storage unit that stores in advance a processable sheet amount capable of processing the sheet on which the feeding unit is placed, and the control unit includes the storage unit. A sheet feeding control device for prohibiting the feeding operation of the feeding means when a distance measuring sensor detects a placed sheet exceeding the sheet amount stored in the sheet feeding means. 7. The control means determines a relationship with a predetermined distance based on the measured distance by the distance measuring sensor,
6. The sheet feeding control device according to claim 1, wherein the sheet feeding control device also serves as a detection unit that detects the presence or absence of a document placed on the loading tray.