JPH06298400A - Paper sheet feeder - Google Patents

Abstract

PURPOSE:To detect the double feed of documents immediately after its occurrence and easily recover it during the image reading action or the image forming action. CONSTITUTION:An automatic paper feeder separately feeds documents O via a separation section 33 and a rotary roller 31. The change of the thickness of the documents O is converted into the electric signal via a pressure-sensitive conducting rubber in the separation belt 253 of the separation section 33 or a pressure-sensitive conductive rubber in a feed roller facing the separation section 33, and the conveyance state at the time of the double feed of the documents O is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device such as an automatic document feeder used in an image forming apparatus such as a copying machine.

[0002]

2. Description of the Related Art Conventionally, there is a known example of an automatic sheet feeder (sheet feeder) using a pressure sensitive sensor.

An example thereof is Japanese Patent Laid-Open No. 63-117823. In this system, a pressure sensor is attached to the paper guide of the document feed table to detect that the side surface of the paper comes into contact with the guide. The purpose of this known example is to solve the problem that the document guide must be set again after being aligned with the document. That is, the document guide is automatically set.

Another known example is JP-A-63-28156.
No. 9 publication. The purpose of this is to detect the pressure applied to the take-out roller at the paper take-out portion with a pressure sensor and adjust the pressure applied to the take-out roller. By this pressure adjustment, the paper can be taken out stably.

Further, as a known example for detecting the thickness of the paper being fed, there is JP-A-2-127327. It detects the displacement of the paper feed roller. In this embodiment, a non-contact micro displacement sensor (for example, a laser displacement sensor manufactured by Keyence Corporation) is used. There is no.

Further, the purpose of detecting the thickness of the paper is to reliably convey the paper by adjusting the pressing force of the pressure roller in the paper feeding section for reversing the original according to the thickness of the paper.

Japanese Laid-Open Patent Publication No. 4-52780 describes an embodiment in which double feeding of sheets is detected, separate output destinations for double fed documents and other documents are provided, and only double fed documents are extracted. There is.

In this embodiment, two types of double feed detection methods are described.

The displacement of bearings of a pair of rollers for feeding a sheet is read by an optical displacement sensor.

Another method is to detect the thickness of a document being conveyed by using a capacitance sensor.

Further, a plurality of originals are once input to a document reading device, standard deviations and variances of the thickness and length of the target document are calculated, and double feeding is detected based on the values.

Japanese Unexamined Patent Publication No. 3-107174 discloses an automatic document feeder for feeding a document to a copying machine, and counts and displays copied documents based on a detection signal from a paper discharge sensor of the automatic document feeder. Examples have been described.

However, in the first known example, the pressure sensitive sensor is used only for turning on and off, and the automatic setting of the document guide is only realized. Moreover, there is no specific description of the pressure-sensitive sensor.

Further, in the second known example, the pressing force is only adjusted in order to ensure the stability of taking out the paper. Further, like the first known example, there is no specific description of the pressure sensitive sensor.

In the third known example, similarly, the pressing force is merely adjusted in order to improve the reliability of paper conveyance. Further, the means for measuring / detecting the displacement of the transport roller is expensive and impractical.

In the fourth known example, by the displacement sensor,
The method of detecting the displacement amount of the conveyed roller has the following problems.

In this embodiment, the resolution of the displacement sensor is 1
Although it is described as about 10 μm, such a displacement sensor is very expensive, and since the accuracy of the outer diameter of the roller that conveys the sheet is 5 to 10 μm, the displacement of the sheet is Before the reading, there is a problem that the displacement data is largely shaken and it becomes difficult to detect the actual double feed.

In the means for detecting the thickness of the original using the electrostatic capacity sensor, even if the same original is detected even if the electrostatic capacity of the conveyed sheet is low or the humidity is high, There is a problem that the result of the detection of the difference is different. In the worst case, a leak may occur between the terminals that detect the capacitance, and the detection circuit may be damaged.

If the original is linear, the thickness will appear as a change in the capacitance accurately. However, when the original is curled or between the electrodes of this detecting device. Therefore, if the degree of bending of the document is changed, it becomes difficult to accurately detect the thickness. That is, since it is already known that the original document is usually flexible and the bending degree changes during transportation, this method is impractical.

Even if the document is once read for trial and the double feed is detected based on the thickness and length data, if the double feed frequency is different from that at the time of trial reading, it is determined that the double feed has occurred. Error will occur.

In the fifth known example, the number of originals for which copying has been completed is counted and displayed by the paper discharge sensor of the automatic document feeder. In this case, the user, who is the user, must count the number of documents input to the automatic document feeder in advance, compare the count with the displayed count, and detect the double feed by itself. Needless to say, this is a great burden on the user when a large amount of documents are copied or stored in a medium such as communication and an optical disk.

By the way, it is very important to detect the double feeding of papers in the paper feeding, especially in the apparatus for feeding the originals. Automatic paper feeders are used not only in copying machines, but also in facsimiles, optical disk file devices and the like. In a copying machine, when double feeding, it is possible to check the copied paper immediately. However, in this case, the user needs to be on the side until the end of the operation in order to constantly check the operation of the copying machine. In addition, as in recent years, as the speed and capacity of copiers have increased, even if double feed is found, a large number of useless copies are generated before the operation of the copier is stopped.

On the other hand, in a facsimile or an optical disk file device for converting image information of an original into an electric signal, double feeding of the original is a more serious problem. In a facsimile, it is not possible to determine whether or not a multi-feed has been made from the copied paper, and there are few cases in which the lack of information due to a multi-feed is notified by an inquiry from the destination. In this case, it is not only rude to the destination, but the facsimile communication is repeated once again.

In the optical disk file device, when the image information is converted into an electric signal and stored in a storage medium such as an optical disk, in order to confirm whether or not the multi-feed has been made, the information is recalled from the optical disk and a CRT or the like is called. It will be checked by the display means. This significantly impairs the office automation (OA) effect of the optical disk file device that can store a large amount of information.

As described above, the importance of detecting double feed has been recognized, but the means for realizing it has been left uninvented.

[0026]

By the way, in the conventional sheet feeding apparatus, when the originals placed on the original feeding table are fed one by one, the coefficient of friction between the separation belt and the originals. Is μ _P1 , and the friction coefficient between the paper feed roller and the original is μ
_P2 , when the friction coefficient between documents is μ _PP , μ _P2 > μ
If the relationship of _P1 > μ _PP is satisfied, only the document on the bottom surface will be fed and the separation function will be performed reliably.

However, in reality, there are various originals, and the friction coefficient may differ between the upper surface and the lower surface of the original. In such a case, the condition of the friction coefficient cannot be satisfied, and the documents are fed in duplicate. Further, when the humidity is low, static electricity is generated between the originals, so that the originals stacked may not be separated and may be sent.

When the document thus double-fed is supplied to the image reading device, information is lost, which may cause a paper feed failure. In the worst case, not only is the document set again in the paper feeding device, but also the document is damaged.

Further, even when supplying to the image forming apparatus,
The following problems occur.

Even when copying a plurality of copies from a plurality of originals, if the originals are double-fed, pages will be lost, and if a large number of copies are to be made, a large amount of copy paper will be wasted if copying is repeated from the beginning. Become.

Further, in the case of performing a double-sided copy of a plurality of copies, after copying the sheets on the front side, stacking the copy sheets and supplying the copy sheets to the image forming apparatus again, if the sheets are double-fed, the copying operation is interrupted. However, there is a problem that the user has to restart the copying of the table or carry out the manual paper feeding only for the number of copies that are double-fed.

According to the present invention, however, the pressure-sensitive conductive rubber is used for the feeding rotary member, and the double feed is detected by converting the change in the length and thickness of the document into an electric signal. Double feeding of documents can be reliably detected, and an image reading operation or an image forming operation can be detected immediately after double feeding, and recovery can be facilitated.

[0033]

A paper sheet feeding device of the present invention is a storage means for storing a plurality of paper sheets, a conveying means for conveying paper sheets, and the storage means. A take-out means for taking out the paper sheets one by one and supplying them to the conveying means,
A feeding rotating means provided on the conveying means for feeding the paper sheets taken out by the taking-out means, abutting against the feeding rotating means, and rotating in a direction opposite to the rotating direction of the feeding rotating means. 2 by the above-mentioned taking-out means
It is composed of a separating means for separating the sheets after the first sheet from the sheet for the first sheet, and the separating means is a pressure-sensitive conductive rubber whose resistance value is changed by the applied pressure, and this conductive sheet. A conductive material provided on the outer side of the rubber is laminated, and the pressure due to the feeding of the paper sheet fed between the feeding rotation means and the feeding rotation means is set by the pressure-sensitive conductive rubber. Is output as a change in.

The paper sheet feeder according to the present invention is a storage means for storing a plurality of paper sheets, a conveying means for conveying the paper sheets, and one paper sheet stored in the storage means. Take-out means for feeding to the carrying means, feeding rotation means provided on the carrying means for feeding the paper sheets taken out by the taking-out means, contacting the feeding rotation means, and feeding the feeding means. The rotating means rotates in a direction opposite to the rotating direction, and is composed of a separating means for separating the second and subsequent paper sheets taken out by the taking-out means from the first paper sheet. The sending and rotating means is constituted by arranging a pressure-sensitive conductive rubber whose resistance value is changed by the applied pressure on the conductive member and a conductive material provided outside the conductive rubber on concentric circles, Accompanying the feeding of paper sheets fed between the separating means The force and outputs it as a change in resistance by the conductive rubber of the pressure sensitive.

[0035]

According to the present invention, in the above-mentioned construction, the paper is separated and fed by the belt-shaped separation brake section and the separation roller. By converting the change in the thickness of the leaves into an electric signal, the conveyance state such as the double feeding of the paper sheets is detected.

According to the present invention, in the above structure,
In the one in which the sheet is separated and fed by the separation brake unit and the separation roller, the separation roller has a pressure-sensitive conductive rubber built therein, and by converting the change in the thickness of the sheet into an electric signal,
It is configured to detect a conveyance state such as double feeding of paper sheets.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a copying machine as an example of the image forming apparatus according to the present invention.

That is, reference numeral 1 is a main body of the copying machine.
A document automatic feeding device (AD) as a paper sheet feeding device of the present invention which automatically conveys a document (paper sheet) O above the
F: Auto document feeder) 20 is installed.

A document table (transparent glass) 2 on which the document O fed by the automatic document feeder 20 is placed is provided on the upper surface of the copying machine body 1.

A document scanning unit 3 for scanning and reading a document O set on a document table 2 is provided in the main body 1 of the copying machine, and an image forming unit 4 is provided below the document scanning unit 3. The original table 2 is fixed to the main body 1.

The document scanning section 3 is constructed, for example, as shown in FIG. That is, the first carriage 7 on which the exposure lamp 6 as a light source is installed, the second carriage 9 on which the mirror portion 8 that bends the optical path is installed, and the zoom lens 1.
0, the reflected light from the document O is guided to the photoelectric conversion unit 11, and the mirror unit 12 that corrects the optical path length at the time of zooming, the photoelectric conversion unit 11 that receives the reflected light from the document O, and the positions of these units are changed. Drive system (not shown) and photoelectric conversion unit 11
Output, that is, image data is converted from analog data to digital data by an A / D converter 13.

The first carriage 7 has an exposure lamp 6 for irradiating the original O with light, a reflector 14 as a reflecting mirror for collecting the light from the exposure lamp 6 on the surface of the original, and a reflected light from the original O. A mirror 15 that guides the second carriage 8 is mounted.

The mirror section 8 is composed of mirrors 8a and 8b for guiding the light guided by the mirror 15 to the zoom lens 10. The first and second carriages 7 and 9
Are connected to each other by a timing belt (not shown), and the second carriage 9 moves in the same direction at half the speed of the first carriage 7. Thereby, scanning can be performed so that the optical path length to the zoom lens 10 is constant.

The zoom lens 10 has a fixed focal length and can be moved in the optical axis direction during zooming.

The mirror section 12 includes two mirrors 12a,
12b, the positions of the mirrors 12a and 12b are changed according to the change of the optical path length corresponding to the selected magnification, and the light from the zoom lens 10 is changed to the two mirrors 12a, By bending the optical path at 12b, the light is guided to the photoelectric conversion unit 11.

The photoelectric conversion unit 11 photoelectrically converts the reflected light from the original O, and is mainly composed of, for example, a CCD type line image sensor. In this case, one pixel of the document O corresponds to one element of the CCD sensor. The output of the photoelectric conversion unit 11 is output to the A / D conversion unit 13.

The movement of the first and second carriages 7 and 9 and the mirrors 12a and 12b is performed by a stepping motor (not shown).

The first and second carriages 7 and 9 are provided with a timing belt (not shown) suspended between a drive pulley (not shown) connected to the rotary shaft of the stepping motor and an idle pulley (not shown). It is designed to be moved according to the movement of.

In the zoom lens 10, a spiral shaft (not shown) is rotated by a corresponding stepping motor (not shown), and this spiral movement moves in the optical axis direction.

The image forming section 4 is composed of, for example, an image forming section combining a laser optical system and an electrophotographic system capable of forming an image on a transfer sheet.

Next, the structure of the automatic document feeder 20 will be described with reference to FIG.

The automatic document feeder 20 is unitized, and the rear end edge of the cover body 21 as a housing thereof can be freely opened and closed on the rear end edge of the upper surface of the copying machine body 1 via a hinge device (not shown). The automatic document feeder 20 is attached so that the entire automatic document feeder 20 can be pivotally displaced to open the original table 2.

As shown in FIG. 1, on the upper surface of the cover main body 21 slightly leftward, a document feed table 22 is provided as a document holding means capable of holding a plurality of documents O all at once.

Further, the originals O held with the image forming surface facing upward by the original feeding table 22 are sequentially taken out one by one from the lower side and supplied to one end side (the left end side in the drawing) of the original table 2. A take-out / feeding means 23 is provided.

The take-out / feeding means 23 is constructed as follows.

That is, the document stopper 2a arranged along the inclined lower end of the document feeding table 22 and the left edge of the document table 2.
Horizontal U-shaped paper feed path 25 so as to communicate with the upper surface of the sheet
Is provided so that the document O is inverted and guided so that the document forming surface faces down.

A shutter 26 for aligning the end faces of the originals O set on the original feeding table 22 is provided upstream of the paper feeding path 25, and a pickup roller 27 for taking out the original O is provided in the vicinity thereof. A weight plate 28 for pressing the original O against the pickup roller 27, an empty sensor 29 as an original detecting sensor for detecting the setting state of the original O on the original feeding table 22, and an actuator 30 of the empty sensor 29 are provided. Has been done.

Further, in the original taking-out direction of the pickup roller 27, a rotating roller 31 as a paper feeding roller,
The rotating roller 31 is provided with a separating portion (described later) 33 which is attached to the frame 32 of the main body and comes into pressure contact with the light body so that the originals O are reliably fed one by one. The separation unit 33 detects the thickness of the original document O, a conveyance state such as double feeding (overlapping conveyance) of the original documents O, and a pressure-sensitive conductive rubber 33a as a separation rubber for detecting opening / closing of the automatic document feeder 20. Built-in (described later). The friction coefficient μ _bs between the separation belt 253 of the separation unit 33 and the original O and the friction coefficient μ _rs between the rotary roller 31 and the original O are larger than the friction coefficient μ _ss between the originals O. Therefore, only the document O on the lowermost surface is separated and conveyed until it hits the aligning rollers 34, 34.

Further, at the downstream portion of the sheet feeding path 25, an aligning roller 3 as a registration roller pair for correcting the inclination (skew) of the original O and adjusting the supply timing.
4 and 34 are provided, and a registration sensor 36 that is located in front of the aligning rollers 34 and 34 and detects the document O to adjust the operation timing of the aligning rollers 34 and 34 is provided. Further, a document size sensor is provided downstream of the aligning rollers 34, 34 to detect the document O and detect the size of the document O.

Further, a document transport belt 37 as a document transport means is stretched to cover the upper surface of the document table 2. Then, the document O fed by the take-out feeding means 23 is conveyed from one end side (left end side) of the document table 2 to the other end side (right end side), and is ejected at the right side portion of the cover body 21. The paper unit 38 discharges the paper to a paper discharge receiving portion 39 formed on the upper surface of the cover body 21.

The original conveying belt 37 is a wide endless belt whose outer surface is hung on a pair of belt rollers 40, 40 and is white and can run in both forward and backward directions by a belt drive mechanism (not shown) described later. Has become. Further, a plurality of belt pressing rollers 41 for pressing the belt surface onto the original table 2 and a set switch 42 used as a release switch at the time of jam are provided on the back surface side of the inner peripheral portion of the original conveying belt 37. Has been.

Further, the paper discharging means 38 is constructed as follows.

That is, the right edge of the document table 2 and the paper discharge receiving portion 3
A lateral U-shaped sheet discharge path 43 is provided so as to communicate with the sheet 9, and the original O is inverted and discharged so that the original forming surface faces up.

A transport roller 44, a pinch roller 45 for pressing the document O on the transport roller 44, and a document detecting means for detecting the trailing end of the document O fed in the sheet discharge direction are provided in the middle portion of the paper discharge path 43. The paper discharge sensor 46 and the actuator 47 of the paper discharge sensor 46 are provided.

On the downstream side of the paper discharge path 43, a paper discharge roller 48 is provided and a plate spring 49 for pressing the original O on the paper discharge roller 48 is provided.

Reference numeral 50 in the figure denotes a cover switch.

Next, the operation of the automatic document feeder 20 thus configured will be described with reference to FIGS. 3 (a) to 3 (d).

First, as shown in FIG. 3A, a plurality of originals O are collectively set (placed) on the original feeding table 22 so as to abut against the shutter 26. This manuscript O
The actuator 30 is rotated and the empty sensor 29 is turned on by the mounting. On the other hand, an operation panel 52 described later
Enter the required information from. After this, copy key 52c
push. As a result, the shutter solenoid 68 and the weight plate solenoid 70 are turned on, the weight plate 28 suppresses the lifting of the original O, and the shutter 2 from the conveyance path 25.
6 retreats. Further, the pickup roller 27 and the rotation roller 31 rotate, respectively, and the lowermost first original O on the original feeding table 22 is taken out and fed, and a pair of registration rollers 34 and 34 are used to intervene. And is fed to the lower surface side of the document transport belt 37 which is running in the feeding direction (see (b) and (c) of FIG. 3).

Then, the document is fed onto the document table 2, and thereafter, in order to abut the document O against the document stopper 24, after the trailing edge of the document O is detected by the registration sensor 36, the document transport belt 37 travels for a certain number of pulses. After that, the original conveying belt 37 is moved in the reverse direction for a certain number of pulses to move the original O.
And the setting of the original O is completed.

When the setting of the original document O is completed, the original document scanning unit 3 in the copying machine body 1 scans the original document, and the image forming unit 4 starts the copying operation on the sheet as the transfer sheet. Will be done.

After the copying operation is completed, the original O is sent out from the original table 2 as the original conveying belt 37 travels, and is discharged to the discharged paper receiving portion 39 via the paper discharging means 38 (see FIG. 3). (See (d)).

On the other hand, when the original O is sent out from the original table 2, the next original O is sent to the original table 2. Then, this operation is repeated until there is no original O set on the original feed table 22.

Next, the control circuit will be described with reference to the block diagram shown in FIG.

That is, a main controller 51 for controlling the entire copying machine 1 is provided. The main control unit 51 includes an operation panel 52 for instructing various operations, the document scanning unit 3,
An interface 53 for exchanging data with the image forming unit 4 and the automatic document feeder 20 is connected.

The operation panel 52 has a display section 52a for displaying operation contents and the like, and a setting key 52 for making various settings.
.., a copy key 52c for instructing the start of copying, an input mode switching key 52d, a clear key 52e, and the like.

The automatic document feeder 20 is provided with a control unit 61 for controlling the entire automatic document feeder 20.
The control unit 61 includes a driver 63 that drives a feeding motor 62 that is a drive source of the pickup roller 27 and the rotating roller 31, aligning rollers 34, 34, a document conveyance belt 37, a conveyance roller 44, and a paper discharge. Laura 4
8, a driver 65 for driving a conveying motor 64, which is a drive source of the drive source 8, the empty sensor 29, the document size sensor 3
5, a registration sensor 36, a set switch 42, a paper discharge sensor 46, a cover switch 50, a driver 67 that drives an electromagnetic clutch 66 that interrupts the transmission of the rotational force of the conveying motor 64 to the aligning rollers 34, 34, A driver 69 that drives a shutter solenoid 68 that rotates the shutter 26, a driver 71 that drives the weight plate solenoid 70 that rotates the weight plate 28, a memory 72 that stores various data, and a detection circuit 73. An A / D converter 74 for converting a voltage value into a digital value and an interface 60 for exchanging data with the copying machine 1 are connected.

The A / D converter 74 has an inversion output function, and the voltage from the detection circuit 73 for detecting the voltage value obtained by the resistance value change of the pressure-sensitive conductive rubber 253b in the separation belt 253 of the separation unit 33. The digital value corresponding to the change in the value is output to the control unit 61. While the voltage value from the detection circuit 73 decreases, it outputs a digital value increasing in the positive direction.

The control section 61 is adapted to judge the carrying state such as double feeding (two-sheet overlapping feeding) of the original O based on the digital value supplied from the A / D converter 74. For example, when a digital value corresponding to the voltage value “V0” from the detection circuit 73 is supplied from the A / D converter 74,
It is determined that the original O is not conveyed, and the digital value corresponding to the voltage value “V1” from the detection circuit 73 is A / A.
When the document O is supplied from the D converter 74, it is determined that the document O is normally conveyed, and when the digital value corresponding to the voltage value “V2” from the detection circuit 73 is supplied from the A / D converter 74. , Determine whether the document O is double-fed.

The separating unit 33 is shown in FIG. 1 and FIG.
(B), as shown in FIG. 6 and FIG. 7, pressure-sensitive conductive rubber 253
It is composed of a separation belt 253 having a belt shape having b.

That is, the separation belt 253 has the conductive layer 2
A pressure-sensitive conductive rubber 253b is laminated on the upper portion of 53a, and a conductive layer 25 for signal detection is formed on the pressure-sensitive conductive rubber 253b.
3c has a laminated structure.

The separation belt 253 has two rotating rollers 2
It is hung on 51, 252. Rotating roller 251,
Support shafts 251a and 252a of 252 are bearings 255, 255, 256 and 25 made of a conductive material and provided on a frame 254 of the automatic document feeder main body.
6 is rotatably supported.

The conductive layer 253c of the separation belt 253 includes
The signal detection roller 257 is arranged in contact with the conductive layer 253a of the signal detection roller 257 while rotating together with the separation belt 253. A harness 258 is connected to the signal detection roller 257. As a result, the separation belt 25
The third conductive layer 253c and the other input end 73b of the detection circuit 73 are connected via the signal detection roller 257 and the harness 258. The signal detection roller 257
Is made of a material having both springiness and conductivity, such as SUS or phosphor bronze, and is rotatably supported by the support member 259.

The frame 254 has a harness 26.
0 is connected, and the harness 260 allows the pressure-sensitive conductive rubber 253b of the separation belt 253 and the detection circuit 7 to be connected.
3 is connected to one of the input ends 73a through the conductive layer 253a, the rotating roller 251, the support shaft 251a of the rotating roller 251, the frame 254, and the harness 260.

Instead of the signal detection roller 257, a conductive brush 261 having a width corresponding to a part of the conductive layer 253c may be provided as shown in FIG. In this case, the signal from the conductive brush 261 is transmitted through the support member 262 and the harness 263 to the other input end 73b of the detection circuit 73.
Have been led to. As described above, by using the conductive brush 261, it has a cleaning function for the signal detection portion and a signal detection function.

Further, as shown in FIG. 9, the conductive brush 2
61 may be provided so as to be in contact with the entire conductive layer 253c. Thus, the conductive brush 261
By using, it is possible to have both a function of detecting a signal and a function of cleaning an adhering material such as paper dust on the feeding belt 253.

The signal from the pressure-sensitive conductive rubber 253b is
Conductive layer 253a, rotating roller 251, rotating roller 251
Support shaft 251a, frame 254, and harness 2
The voltage is supplied to one input end 73a of the detection circuit 73 via 60 and the detection circuit 7 via the conductive layer 253c, the signal detection roller 257, and the harness 258.
3 is supplied to the other input terminal 73b.

For example, when the original O is not sandwiched between the separating belt 253 as the separating unit 33 and the rotating roller 31, the pressure on the separating belt 253 is P0 and the output voltage from the detection circuit 73 is V0. Therefore, when one original O is sandwiched between the separating unit 33 and the rotating roller 31, the pressure on the separating belt 253 is P1 and the output voltage from the detection circuit 73 is V1, When two originals O (two originals O) are sandwiched between the separating unit 33 and the rotating roller 31 (double feeding of the originals O), the pressure on the separating belt 253 is P2, and the detection circuit 73 detects Output voltage is V2 (P2>P1> P0, V0>
V1> V2).

The relationship between the pressure of the separating section 33 and the output voltage of the detection circuit 73 is as shown in FIG.

The pressure-sensitive conductive rubber 253b is made of a polymer material in which a conductive filler is dispersed so that the material is made conductive by a conductive elastomer.
(Elastic polymer such as silicone rubber). The pressure-sensitive conductive rubber 253b is an elastomer of the conductive elastomer capable of taking out a resistance change in response to a pressure stimulus, and is a pressure conductive rubber Pressure sensiti
ve Conductive Rubber; Also called PCR.

11 and 12 show the relation between typical pressure and resistance value of the pressure-sensitive conductive rubber 253b.

FIG. 11 shows the pressure dependence of the pressure-sensitive conductive rubber 253b in which carbon black is dispersed in the elastomer.

FIG. 12 shows the pressure dependence of the pressure-sensitive conductive rubber 253b in which conductive metal particles (for example, a particle diameter of 10 μm or more such as copper or nickel) are dispersed in silicon rubber.

In the case of FIG. 11, there is a resistance value change of about 2 to 3 digits, and in the case of FIG. 12, there is a resistance value change of 6 digits or more from 10 ⁸ Ωcm or more to 10 ² cm or less in volume resistivity. .

Further, in the above example, the pressure sensitive conductive rubber 253b was provided in the separation belt as the separation portion.
As shown in FIG. 5, the feeding roller 152 facing the separating roller 153 as the separating portion may have the pressure-sensitive conductive rubber 152b. As shown in FIG. 14, the feeding roller 152 has a structure in which a pressure-sensitive conductive rubber 152b and a conductive layer 152c are laminated on a concentric circle of a conductive roller shaft 152a.

In this case, the original O taken out by the take-out roller 151 is separated and fed to the separating roller 153 and the feeding roller 152 into the originals O one by one, and fed by the aligning roller pair 154 and 154. Guide 155
And 156, and is fed onto the above-mentioned document table 2. Aligning roller pair 15
4, an actuator 157 of a feeding detector (not shown) is provided near the rollers 4, 154, and the aligning roller pair 1 of the original O is rotated by the rotation of the actuator 157.
Delivery to 54, 154 is detected.

The separating roller 153 is connected to the arm 159 via the shaft 158, and is pressed against the feeding roller 152 by the spring force of the spring 160 connected to the arm 159. The spring force of the spring 160 is equal to the adjustment screw 161.
It can be adjusted by. Also, guide 1
By guiding the light from the light source 162 through the notch 56, the reflected light from the guide 155 or the reflected light from the document O by the light is guided to the detector 165 via the mirror 163 and the lens 164. The passage of the document O is detected.

As shown in FIG. 15, the detection circuit 73 includes resistors R1 to R10, variable resistors VR1, VR2, and VR.
3, current detection type transistors Tr1 and Tr2, and an operational amplifier OP. Detection circuit 73
Is supplied with the change in resistance value from the feeding rotating body 35 to the input ends 73a and 73b. The supplied current with respect to the change in the resistance value is adjusted by the variable resistors VR1 and R1 and becomes the base current of the transistor Tr1. Since the amplitude of the change in the supplied resistance value is unknown, it is not a fixed resistance,
A variable resistor (volume resistor) VR1 is provided. The base current of the transistor Tr1 is detected by the current detection rate of the transistor Tr1, and the emitter current of the transistor Tr1 is divided by the resistors R4 and R5. The current passing through the resistor R4 is detected by the transistor Tr2 at the current detection rate of the transistor Tr2, and the emitter current of the transistor Tr2 is divided by the resistors R6 and R7. The current passing through the resistor R7 is detected by the operational amplifier OP based on the reference voltage by VR3 / R7 times which is determined by the variable resistor VR3 and the resistor R7.
The reference voltage input to the non-inverting input terminal of the operational amplifier OP is for input offset adjustment, and the variable resistor V
Adjusted by R2. The signal (voltage value) detected by the operational amplifier OP is output to the A / D converter 74 via the resistor R10.

In the above example, two transistors Tr1,
The current detection rate was increased by using 2, but not limited to this,
You may make it use only one transistor Tr1. In this case, the detection circuit 73 has a transistor Tr.
A signal is output from 1 through the resistor R4.

Depending on the signal supplied to the input terminal 73b, it is necessary to insert another resistor between the input terminal 73b and the resistor R1.

Next, the operation of the above structure will be described with reference to FIGS. 3 (a) to 3 (d).

First, as shown in FIG. 3A, a plurality of originals O are collectively set (placed) on the original feeding table 22 so as to abut against the shutter 26. This manuscript O
The actuator 30 is rotated and the empty sensor 29 is turned on by the mounting. On the other hand, necessary information is input from the operation panel 52. Then, the copy key 52c is pressed.
As a result, the control unit 61 turns on the shutter solenoid 68 and the weight plate solenoid 70. As a result, the weight plate 28 suppresses the lifting of the original O, and the conveyance path 25
The shutter 26 retracts from.

The control section 61 is rotated by transmitting the rotational force of the sheet feeding motor 62 to the pickup roller 27. As a result, the original O on the original feeding table 22 is taken out and sent between the separating unit 33 and the rotating roller 31. At this time, the rotating roller 31 is stopped. When the control unit 61 receives an operation start command from the main control unit 51, the control unit 61 outputs the operation start command via the various timing generation circuits 101 and transmits the rotational force of the sheet feeding motor 62 to the rotating roller 31 to rotate the same. . As a result, the lowermost first original O on the original feeding table 22 is fed by the separating unit 33 and the rotating roller 31, and the aligning rollers 34, 3 are also provided.
It is fed to the lower surface side of the document conveying belt 37 which is running in the feeding direction via the pair of registration rollers 4 (see (b) and (c) of FIG. 3).

Then, when a certain time has elapsed since the pickup roller 27 and the rotating roller 31 were rotated, the control section 61 changes the digital value from the A / D converter 74 to the voltage value "V0" from the detection circuit 73. , The original O is not conveyed and a jam is determined. Further, when the digital value from the A / D converter 74 is a value corresponding to the voltage value “V2” from the detection circuit 73, it is judged that the document O is double-fed.

When the jam is judged, the control unit 61 stops the paper feeding motor 62 and the conveyance motor 64, and outputs the occurrence of the jam to the main control unit 51 of the copying machine main body 1 through the interfaces 60 and 53. To do. The main control unit 51 guides the occurrence of the jam with the operation panel 52.

When it is determined that the multi-feed has occurred, the control unit 6
1, the feeding motor 62 and the conveying motor 64 are stopped,
The occurrence of jam is output to the main controller 51 of the copying machine main body 1 through the interfaces 60 and 53. The main control unit 51 guides the occurrence of the double feed by the operation panel 52.

That is, by rotating the pickup roller 27, the original O is sent between the separating portion 33 and the rotating roller 31, as shown in FIG. At this time, the rotating roller 31 is stopped.

When the rotation of the rotary roller 31 is started, the rotary roller 31 and the original O, the originals O,
Due to the relationship of the friction coefficient between the separating portion 33 and the original O, only one original O is fed by the rotary roller 31 with the passage of time. This is shown in (b) and (c) of FIG.
It shows in (a) of FIG. Therefore, the rotating roller 31
However, the document O
The double feed may be detected by detecting the thickness of the sheet. If, after this period has elapsed, if the document is double-fed as shown in FIG. 19B, a change in pressure due to a difference in the thickness of the document O can be detected.

When the document O is normally fed onto the document table 2, the document conveying belt 37 is moved after the document size sensor 35 detects the trailing edge of the document O in order to hit the document O against the document stopper 24. After traveling for a certain number of pulses, the original conveying belt 37 is moved in the opposite direction for a certain number of pulses to return the original O and the setting of the original O is completed.

When the setting of the original O is completed, the original scanning unit 3 in the main body 1 of the copying machine scans the original, and the image forming unit 4 starts the copying operation on the paper as the transfer paper. Will be done.

After the document scanning by the document scanning unit 3 is completed, the document O is sent out from the document table 2 as the document transport belt 37 travels, and is discharged through the sheet discharging means 38.
It is discharged to 9.

That is, when the actuator 43 is rotated by the leading edge of the original O and the paper discharge sensor 38 is turned on, the controller 61 stops the traveling of the original conveying belt 37. Further, after the discharge sensor 38 is turned off by the trailing edge of the document O (passing) and a predetermined time (several tens of msec) has elapsed, the control unit 61.
Stops the transport roller 44 and the paper discharge roller 48.

On the other hand, when the original O is sent out from the original table 2, the next original O is sent to the original table 2. Then, this operation is repeated until there is no original O set on the original feed table 22.

Next, a thickness detecting circuit for detecting the thickness of the original O based on the output signal (voltage value) from the A / D converter 74 of FIG. 4 is provided. An example in which the multi-feeding of the original O as the conveyance state is determined will be described. In this case, the control circuit is the A / D converter 7 of FIG.
4 and the control unit 61, a thickness detection circuit 100 is provided.

The thickness detecting circuit 100 sends the information in accordance with the digital value from the A / D converter 74 corresponding to the change in the voltage value from the detecting circuit 73 obtained by the change in the resistance value of the separating section 33. The thickness of the original O to be fed is detected, and whether the thickness of the second or subsequent original O fed is thicker than the reference, based on the thickness of the first original O fed. It outputs a detection signal indicating whether or not the thickness of the first original O is 2
A detection signal indicating whether or not the thickness of the original document O is thicker is output to the control unit 61.

The control section 61 determines whether or not the original O is conveyed abnormally based on a detection signal from the thickness detection circuit 100.
For example, when the detection signal is supplied from the thickness detection circuit 100 that the thickness of the second original document O is thicker than the reference, the control unit 61 determines the double feeding of the second original document O or later. , The thickness of the first document O from the thickness detection circuit 100 is 2
When a detection signal that the thickness of the first original O is thicker is supplied, it is determined that the first original O is double-fed.

As shown in FIG. 16, the thickness detecting circuit 100 includes various timing generating circuits 101 and a number counter 10.
2, an FF circuit 103, an inverter 104, AND gates 105 and 106, delay circuits 107 and 108, a latch circuit 109, and a comparator 110.

The various timing generation circuits 101 generate various timing signals in accordance with various commands supplied from the control section 61, and in accordance with the operation commands to the rotary roller 31 of the originals O one by one, It outputs a separation roller operation command to the driver 63 as shown in (a) of 17.

The various timing generation circuits 101, after a predetermined time elapses after the separation roller operation command is output,
The sampling pulse is output as shown in (a) of FIG.
02, AND gates 105 and 106, latch circuit 109
Is output to.

The various timing generation circuits 101 have a built-in counter 101a for counting a master clock from an oscillator (not shown). This counter 10
1a starts counting up from "0" as the paper feed operation command rises.

When the count value of the counter 101a reaches a predetermined number, the various timing generation circuit 101 outputs the sampling pulse shown in FIG. 17 (b). This output is output only once, as shown, when the paper feed roller operation command is at "H" level.

The number counter 102 counts the number of originals O fed by the sampling pulses from the various timing generation circuits 101, and the counting result is output to the controller 61.

The FF circuit 103 is a D-type flip-flop, the data input terminal D and the clock input terminal CLK are held at "H" level, and the clear input terminal CLR operates the separation roller from the various timing generation circuits 101. A pulse corresponding to the command is supplied, and the preset input terminal PR
A preset signal (“L” level) as shown in FIG. 17C from the control section 61 is supplied to E. The preset input terminal PRE is normally held at "H" level.

As a result, the FF circuit 103 causes the chip select signal (Q output) to go to "H" level by the preset signal from the control section 61, as shown in FIG. After the pulse corresponding to the command becomes "L" level, the chip select signal becomes "L" level. That is, the first original O
The chip select signal is switched from the "H" level to the "L" level at the time when the signal has passed, and is held at the "L" level thereafter.

The chip select signal from the FF circuit 103 is supplied to the delay circuit 107 via the inverter 104 and the AND gate 105, and also the AND gate 106.
Is supplied to the delay circuit 108 via.

The AND gates 105 and 106 open the gates by sampling pulses from the various timing generation circuits 101, and the chip select signals from the FF circuit 103 are output to the delay circuits 107 and 108.

The delay circuits 107 and 108 have a latch function of temporarily storing the digital value from the A / D converter 74, and delay the stored digital value for a predetermined time and output it. The output of the delay circuit 107 is supplied to the latch circuit 109, and the output of the delay circuit 108 is the comparator 1
Supplied to 10. By using the delay circuit 108, it is possible to allow the thickness detection even when the conveyance timings of the second and subsequent originals O are deviated.

That is, the latch circuit 109 latches the digital value from the delay circuit 107 according to the sampling pulse from the various timing generation circuits 101. As a result, the data indicating the thickness of the first original O at the predetermined position is latched. This latch circuit 109
The latched contents of are supplied to the comparator 110.

That is, the first original O is separated by the separation unit 33.
The inverter 1 is sandwiched between the sheet feeding roller 31 and the sheet feeding roller 31.
Since the output of 04 is at "L" level, when the sampling clock is at "L" level, CS of the delay circuit 107 is output.
The terminal becomes "L" level and becomes operable.

The delay circuit 107 can operate only when both the signal outputs are at the "L" level.

Therefore, the data indicating the thickness of the first original O is converted into digital data by the A / D converter 74 and then temporarily stored in the delay circuit 107 as DATA1.

DATA temporarily stored in the delay circuit 107
1 is output to the latch circuit 109 as DATA2. A sampling pulse is input to the LT terminal of the latch circuit 109.

When the sampling pulse rises, the latch circuit 109 latches DATA2.

On the other hand, the AND gate 106 is supplied with the chip selector signal and the sampling pulse.

The output of the AND gate 106 is the delay circuit 1
It is input to the CS terminal 08.

The delay circuit 108 becomes operable only when both of the above signal outputs are at "L" level.

While the first original O is sandwiched between the separating section 33 and the paper feed roller 31, the chip selector signal is
Since it is at the “H” level, the delay circuit 108 is in the idle state.

When the separation operation of the first original O is completed, the chip selector signal becomes "L" level, the output of the inverter 104 becomes "H" level, and the output of the AND gate 105 becomes "H". Become a level.

Therefore, delay circuit 107 is in a resting state.

On the other hand, since the output of the AND gate 106 is the "L" level of the chip selector signal, the C of the delay circuit 108 is present when the sampling pulse is at the "L" level.
The S terminal becomes "L" level, and the delay circuit 108 becomes operable.

Therefore, when the separation operation for the second and subsequent sheets is being performed, the signal indicating the thickness of the second and subsequent sheets is sent to the delay circuit 108 as data of the thickness of the second and subsequent originals O. D
ATA4 is input and stored. The data DATA3 stored in the latch circuit 109 and the data DATA5 stored in the delay circuit 108 are sent to the comparator 110.

The comparator 110 has a built-in subtractor, and data within a predetermined range based on the thickness data for the first original O supplied from the latch circuit 109 and the second sheet supplied from the delay circuit 108. By comparing the thickness data with respect to the subsequent originals O, the second and subsequent originals O
Signal that the thickness of the original is the same as the thickness of the first original O,
A signal indicating that the thickness of the second original document O is thicker than the thickness of the first original document O and a signal indicating that the first original document O is thicker than the second original document O. The signal is output to the control unit 61.

For example, the comparator 110 outputs 3-bit comparison results CPR1, CPR2 and CPR3. When the length of the first original O is thicker than the thickness of the second and subsequent originals O, the comparison result CPR1 is set to the "L" level, and the second and subsequent originals O have the same thickness. If it is thicker than the thickness of O, the comparison result CPR2 is set to the “L” level, and if the thickness of the second and subsequent originals O is the same as the thickness of the first original O,
The comparison result CPR3 is set to "L" level.

The comparator 110 and the control section 61 may be connected by three signal lines or may be connected by three-state signal lines.

Next, in such a configuration, as shown in FIG.
The operation will be described with reference to the flowchart shown in FIG. For example, now, a plurality of originals O are collectively set (placed) on the original feeding table 22 so as to abut against the shutter 26. When the document O is placed, the actuator 30 is rotated and the empty sensor 29 is turned on. On the other hand, necessary information is input from the operation panel 52. Then, the copy key 52c is pressed. Thereby, the control unit 61
Is a shutter solenoid 68 and a weight plate solenoid 70
And turn on. As a result, the weight plate 28 suppresses the lifting of the document O, and the shutter 26 retracts from the transport path 25.

Further, the control section 61 instructs the pickup roller 27 and the rotating roller 31 to transmit the rotational force of the sheet feeding motor 62, thereby rotating each of them. As a result, the first original O on the lowermost surface of the original feeding table 22 is taken out and fed, and is moved in the feeding direction via the registration roller pair including the aligning roller 34 and the feeding rotator 35. It is fed to the lower surface side of the original document transport belt 37.

When the first original document O passes between the separating portion 33 and the rotary roller 31, the data corresponding to the thickness of the first original document O is used as a reference value, and the thickness detecting circuit is used. 1
The data is stored in the latch circuit 109 in 00.

That is, when the leading edge of the first original O reaches between the separating section 33 and the rotating roller 31, the control section 61 is operated.
In response to the instruction from, the separation roller operation command is output from the various timing generation circuits 101. The rotation roller 31 is rotated by the separation roller operation command. After outputting the separation roller operation command, the control unit 61 causes the FF circuit 103 to operate.
By outputting the preset signal to the preset terminal (PRE) of, the FF circuit 103 is set and the chip select signal becomes the “H” level.

Then, after a lapse of a predetermined time from the output of the separation roller operation command, the various timing generation circuits 101 output sampling pulses to the number counter 102, AND gates 105 and 106, and the latch circuit 109. As a result, the number counter 102 counts up, the gates of the AND gates 105 and 106 are opened, the chip select signal is supplied to the delay circuit 107, and the delay circuit 107 receives the first original from the A / D converter 74. Thickness data for O is stored as a reference value.

The trailing edge of the first original O is separated by the separating portion 3.
When passing between 3 and the rotary roller 31, the separation roller operation command from the various timing generation circuits 101 becomes "L" level, the FF circuit 113 is cleared, and the chip select signal becomes "L" level.

When the first original O is normally fed onto the original table 2, the first original O is placed on the original stopper 2.
4, the document conveying belt 37 travels for a certain number of pulses after the trailing edge of the document O is detected by the document size sensor 35, and then the document conveying belt 37 travels for a certain number of pulses in the opposite direction. The O is returned and the setting of the original O is completed.

When the setting of the first original O is completed, the original scanning unit 3 in the main body 1 of the copying machine scans the original, and accordingly, the image forming unit 4 sets a sheet as a transfer sheet. The copying operation will be started.

After the document scanning by the document scanning unit 3 is completed, the first document O is sent out from the document table 2 as the document conveying belt 37 travels, and is discharged via the paper discharging unit 38. It is discharged to 39.

On the other hand, when the first original O is sent out from the original table 2, the second original O is sent from the original feeding table 22 onto the original table 2 as described above.

By passing the second original document O between the separating portion 33 and the rotating roller 31, the data corresponding to the thickness of the second original document O and the thickness of the first original document O are changed. The corresponding reference value is compared and the comparison result is output to the control unit 61.

That is, when the leading edge of the second original O reaches between the separating section 33 and the rotating roller 31, the control section 61 is operated.
In response to the instruction from, the separation roller operation command is output from the various timing generation circuits 101. The rotation roller 31 is rotated by the separation roller operation command.

Then, after a lapse of a predetermined time from the output of the separation roller operation command, the various timing generation circuits 101 output sampling pulses to the number counter 102, AND gates 105 and 106, and the latch circuit 109. As a result, the number counter 102 counts up, the gates of the AND gates 105 and 106 are opened, the chip select signal is supplied to the delay circuit 108, and the delay circuit 108 receives the second original from the A / D converter 74. Thickness data for O is stored.

Therefore, the comparator 110 outputs data within a predetermined range based on the thickness data of the first original O from the latch circuit 109 and the second original O from the delay circuit 108.
By comparing it with the thickness data of the first original O
Is thicker than the thickness of the second original O, the comparison result CPR1 is set to the “L” level, and the thickness of the second original O is thicker than the thickness of the first original O, Comparison result CP
When R2 is set to the "L" level and the thickness of the second original O is the same as the thickness of the first original O, the comparison result CPR3 is set to the "L" level.

As a result, the control section 61 determines that the thickness detection circuit 1
00, when a detection signal that the thickness of the second original O is thicker than that of the first original O is supplied, the second original O
When the thickness detection circuit 100 supplies a detection signal that the thickness of the first original O is thicker than the thickness of the second original O, the first original O Judge sending.

When the double feed is judged, the control section 61 stops the feeding operation and outputs to the main control section 51 the fact that the double feed has occurred. As a result, the main control unit 51 guides the occurrence of double feed on the display unit 52a of the operation panel 52.

Further, the original O is read from the thickness detecting circuits 100 to 2
When a detection signal indicating that the thickness of the first document O and the thickness of the first document O are the same, the control unit 61 determines that
The original document O is scanned and ejected, and the third original O is fed from the original feed table 22 onto the original table 2 in the same manner as described above.

For the third and subsequent originals, the determination of double feeding is made and processed in the same manner as described above.

Further, in the above example, when a double feed is judged,
Although the case where the feeding operation is stopped and the occurrence of double feeding is guided on the display portion 52a has been described, the display portion 52a may be used to guide the number of documents before the double feeding occurs.

Further, the number counter 102 also includes a control unit 6
Since the preset signal from 1 is supplied, at the time of restart, the sheet number counter 102 is cleared to “0” when the first sheet is double-fed, and when the second and subsequent sheets are double-fed, it is double-fed. The previous number is retained. Accordingly, at the time of restart, the user may set the document on the document feed table 22 from the document O that has been double-fed.

With this structure, at the time of double feeding,
It is not necessary to perform the sheet feeding operation again from the first sheet, and the user can save time.

When a preset signal (“L” level) is supplied from the control unit 61 to the FF circuit 103 when a multi-feed or the like occurs during the feeding operation of a plurality of originals O, , The reference thickness data of the latch circuit 109 is initialized. As a result, the thickness data for the first original O after the double feed is released is stored in the latch circuit 109 as a reference value.

In this way, it is possible to detect the double feed for each document placed on the document feed table 22 with reference to the data of the first document O. Normally, one document (collection of originals O) has the same thickness, so if the reference data is updated for each document when there are no more documents on the original feeding table 22, various thicknesses can be obtained. Document is automatic document feeder 2
Even when set to 0, double feed can be detected.

When the preset signal from the control section 61 is not supplied to the FF circuit 103 when a multi-feed or the like occurs during the feeding operation of a plurality of originals O, the reference of the latch circuit 109 is used. The thickness data for the first original O before the multi-feed is stored and held in the latch circuit 109 as a reference value. The flowchart in this case is shown in FIG. 22 and FIG.
3 shows.

As a result, the first original O
The double feed for can be detected immediately.

24 and 25 are flowcharts in the case where the counting by the number counter 102 is taken into consideration.

By the way, when the shape of the original O to be inserted into the automatic original feeder 20 is known in advance,
It is not necessary to store the data of the first sheet in the latch circuit 109 and compare it.

Specifically, the document O to be fed is a slip, securities, or the like.

In such a case, the reference data is held in the storage means (for example, ROM) that holds the data even when the power of the apparatus is turned off, and the reference data stored in the ROM and the fed original O are stored. By comparing the data, it is possible to determine the paper feed state.

First, the thickness detecting circuit 100 when the size of the original O to be fed is fixed will be described.

As shown in FIG. 26, this thickness detecting circuit 100 includes various timing generating circuits 131 and delay circuits 13.
2, ROM 135, and comparator 136.

With such a configuration, when the leading edge of the original O reaches between the separating section 33 and the rotating roller 31, various timing generating circuits 101 are instructed by the control section 61.
Outputs a separation roller operation command. The rotation roller 31 is rotated by the separation roller operation command. Also, after a predetermined time has elapsed since the separation roller operation command was output, the various timing generation circuits 101 output sampling pulses to the delay circuit 132. As a result, the delay circuit 132 latches the digital value corresponding to the voltage value of the detection circuit 73 from the A / D converter 74.

Therefore, the comparator 136 has the ROM 13
By comparing the data within the predetermined range based on the reference thickness data from No. 5 with the thickness data of the document O from the delay circuit 132, for example, as shown in Table 1, the thickness of the document O is set as the reference. If it is thicker than the thickness, the comparison result CPR4 is set to "L" level, and if the thickness of the document O is thicker than the reference thickness, the comparison result CPR5 is set to "L" level and the document O is set.
, The comparison result CPR6 is set to "L" level.

[0178]

[Table 1] As a result, when the detection signal that the thickness of the original O is thinner than the reference thickness is supplied from the thickness detection circuit 100, the control unit 61 determines the conveyance of different types of original O, and the thickness detection circuit When the detection signal that the thickness of the original document O is thicker than the reference thickness is supplied from 100, it is determined that the first original document O is double-fed.

When it is determined that the multi-feed or the conveyance of the originals O of different types is determined, the control section 61 stops the feeding operation,
The fact that double feed has occurred is output to the main control unit 51. As a result, the main control unit 51 guides the occurrence of double feeding or the conveyance of different types of originals O on the display unit 52a of the operation panel 52.

When a detection signal indicating that the thickness of the original O is the same as the reference thickness is supplied from the thickness detection circuit 100, the controller 61 causes the original scanning of the original O and the discharge processing. At the same time, the next original O is fed from the original feed table 22 onto the original table 2 in the same manner as described above.

The control section 61 may stop the sheet feeding operation as a conveyance abnormality when the thickness detection circuit 100 supplies a signal indicating that the thickness of the original document O and the reference thickness do not match.

Further, reference data for a plurality of originals O having different thicknesses may be prepared in the ROM 135 so that they can be selected by address designation from the control section 61.

In the thickness detecting circuit 100 of the above example, the ROM is used to store the reference thickness data, but the thickness reference data may be set by a dip switch or a rotary switch instead. FIG. 27 shows a schematic block diagram in this case. In this case, it is composed of various timing generation circuits 131, a delay circuit 132, a DIP switch 140, and a comparator 136.

By the way, as shown in FIGS. 28 (a), (b) and (c), in the case where the document O is not fed in a state of being overlapped from the leading end portion of the document O, the document O of the document O is sampled during the thickness sampling. The thickness may vary.

In such a case, if the maximum value of the thickness is not detected, there is a risk of erroneous detection. Therefore, if the peak detection circuit is provided before the reference data and the detection of the second and subsequent sheets, the above problem can be solved. That is, as shown in FIG. 29, between the delay circuit 107 and the latch circuit 109 of the length detection circuit 100 shown in FIG.
And the delay circuit 108 of the length detection circuit 100 and the comparator 1
10 and the peak detection circuits 111 and 112, respectively.
To provide.

The peak detecting circuits 111 and 112 are, for example, as shown in FIG.
122, delay circuits 123 and 124, a latch circuit 125,
126, comparator 127, selector 128, inverter 1
29 and an inverter 130.

That is, as shown in FIG.
Timing pulses from the various timing generation circuits 101 are supplied to the gate control circuits 121 and 122, and digital values from the A / D converter 74 are supplied to the delay circuit 12.
Latch circuits 125 and 126 through 3 and 124, respectively.
Latch clock A (see (b) of FIG. 31) from the various timing generation circuits 101 is supplied to the latch circuit 125 as it is, and its counter output is inverted by the inverter 129. (See c)) is supplied to the latch circuit 126.

The gate control circuits 121 and 122 are in an operable state when the timing pulse from the various timing generation circuits 101 is at the "L" level, and the original O is present in the separating section 33. It only operates on. At this time, the gate control circuits 121, 1
22 opens the gates of the delay circuits 123 and 124, respectively.

In the operable state, the gate control circuit 121 outputs the operation stop signal S1 from the comparator 127.
When (“H” level) is supplied, the latch circuit 125
The gate is closed and the latch contents are retained.
In the operable state, the gate control circuit 122 closes the gate of the latch circuit 126 and holds the latch contents when the operation stop signal S2 (“H” level) is supplied from the comparator 127. .

The latch circuit 125 latches the digital value (thickness data) from the delay circuit 123 when the latch clock A rises when the gate is opened by the gate control circuit 121. The latch contents are output to the comparator 127 and the selector 128.

The latch circuit 126 latches the digital value (thickness data) from the delay circuit 124 when the latch clock B rises when the gate is opened by the gate control circuit 122. The latch contents are output to the comparator 127 and the selector 128.

The comparator 127 compares the latch content A of the latch circuit 125 and the latch content B of the latch circuit 126, and the latch content A of the latch circuit 125 is the latch content 12.
6 is larger than the latch content B of 6 (A> B), the operation stop signal S1 is output to the gate control circuit 121, and the latch content B of the latch circuit 126 is larger than the latch content A of the latch circuit 125 (B ≧ A). The operation stop signal S2 is output to the gate control circuit 122. The above comparator 1
The operation stop signal S2 output from 27 is the inverter 13
It is supplied to the selector 128 via 0 as a selection signal.

When the selection signal supplied from the comparator 127 via the inverter 130 is at "H" level, the selector 128 outputs the latch content A from the latch circuit 125 to the thickness detection circuit 76, and the selection signal is In the case of "L" level, the latch content B from the latch circuit 126 is output to the latch circuit 109 or the comparator 110 in the subsequent stage.

Next, the operation in such a configuration will be described.

First, when the leading edge of the original O reaches the separating portion 33, the voltage detected by the detecting circuit 73 is changed to the delay circuit 123,
It is input to 124. The latch circuits 125 and 126 are configured to latch the outputs of the delay circuits 123 and 124 when the latch clocks A and B rise, respectively.

Therefore, as shown in FIG. 31B, the output of the delay circuit 123 is first latched by the latch circuit 125 by the latch circuit 125.

At this time, since the latch circuit 126 does not operate, the output becomes "0".

Thereafter, the outputs of the latch circuits 125 and 126 are compared by the comparator 127. Latch circuit 12
Since the output of 6 is “0”, the comparator 127 does not supply the operation stop signal to the gate control circuit 122 (“L” level). At this point, the gate control circuit 122
Becomes a state in which the latch circuit 126 receives the output from the delay circuit 124.

On the other hand, from the comparator 127 to the gate control circuit 1
Since the operation stop signal (“H” level) is supplied to 21, the gate control circuit 121 sends the operation stop signal to the latch circuit 125. Therefore, the latch circuit 125 holds the first sampled data as it is.

Since the selector 128 is supplied with the "H" level as the selection signal, the latch content A of the latch circuit 125 is output to the thickness detecting circuit 76.

Next, when the latch clock B rises, only the latch circuit 126 is operating, so that the second sampled data is latched by the latch circuit 126. Here, the data latched in the latch circuit 126 and the data latched in the latch circuit 125 are again compared by the comparator 127.

At this time, when the latch data A of the latch circuit 125 is larger than the latch data B of the latch circuit 126 (A> B), the latch data A is again the latch data 12.
5, the latch circuit 126 latches the data from the delay circuit 124 at the next rise of the latch clock B.

Further, the latch data A of the latch circuit 124
Is smaller than the latch data B of the latch circuit 126 (A ≦ B), the comparator 127 does not supply the operation stop signal to the gate control circuit 121 (“L” level). As a result, the gate control circuit 121 enters a state in which the latch circuit 125 can latch the data from the delay circuit 123.

On the other hand, from the comparator 127 to the gate control circuit 1
Since the operation stop signal (“H” level) is supplied to the gate 22, the gate control circuit 122 sends the operation stop signal to the latch circuit 126. Therefore, the latch circuit 126 holds the second sampled data as it is.

Further, since the "L" level is supplied to the selector 128 as a selection signal, the latch content B of the latch circuit 126 is output to the latch circuit 109 or the comparator 110 at the subsequent stage.

In this way, the sampled data and the data before it are compared, and the larger data is held.

Finally, when the latch data held in the latch circuits 125 and 126 is larger than the latch data A (A ≧ B), the latch data A is output to the thickness detecting circuit 76. . When the latch data A is smaller than the latch data B (A <B), the latch data B is the latch circuit 109 or the comparator 110 in the subsequent stage.
Is output to.

In this circuit configuration, the latch circuit 10 in the subsequent stage is
9 or the comparator 110 has both latch circuits 12
The larger one of the comparison results of 5 and 126 is sequentially output. Finally, the maximum value of the whole one original O is stored in the latch circuit 109 or output to the comparator 110.

With such a configuration, even if the sizes of the originals O are different, it is possible to accurately detect the conveyance state of the originals O without erroneously detecting a double feed.

As described above, by detecting the displacement amount of the pressure-sensitive conductive rubber at the separated portion of the automatic document feeder 20, it is possible to detect double feeding and jam. In addition, when a document that has been double-fed is fed, skew may occur due to uneven thickness, and the document may be pressed against the side surface of the transport path and may be broken or, in the worst case, torn. is there. By performing the detection at the separation portion, it is possible to stop the paper feeding operation immediately after the double feeding, so that such a situation can be prevented.

Further, the automatic document feeder 20 is provided such that it can be opened and closed with respect to the document table 2 of the copying machine main body 1. Therefore, when the automatic document feeder 20 is opened, the separating unit 33
By releasing the pressure during normal use, the output of the detection circuit 73 according to the change in the resistance value of the pressure-sensitive conductive rubber 253b in the separating portion 33 is the original O during normal use.
Is smaller than the output when is not bitten.

By detecting the difference between the outputs, it can be detected that the automatic document feeder 20 is in the open state, and the paper feeding operation can be stopped to prevent malfunction.

Conventionally, a dedicated switch for detecting the open state was required, but with the above configuration, the dedicated switch can be omitted and an inexpensive automatic document feeder 20 can be constructed. it can.

This embodiment will be described below.

For the three states (conditions) for the separation unit 33, the detection circuit 73 (A / D converter 74) to FIG.
A signal as shown in is output.

When the original O is not sandwiched during normal use, the detection circuit 73 outputs a signal of level (a) shown in FIG.

When the original O is sandwiched, the detection circuit 73 outputs a signal of level (b) shown in FIG.

When the automatic document feeder 20 is in the open state, the detection circuit 73 outputs a signal of level (c) shown in FIG.

In the case of FIG. 32, the higher the pressure is, the more the output of the detection circuit 73 under each condition when output is in the upward direction is shown.

First, one example will be described.

Before the automatic document feeder 20 is used,
The operation panel 5 of the main body device or the automatic document feeder 20 at the time of unpacking the setting or at the time of factory shipment
Switch from 2 to service mode.

When in the service mode, the input switch key 52d and the clear key 52e on the operation panel 52 are simultaneously pressed. Then, this signal causes the main control unit 51 and the control unit 61 to enter the service mode.

The method of setting to this service mode may be another method.

Also, the automatic document feeder 2 is equipped with a dedicated circuit.
The open / closed state of 0 may be detected.

An example of this case is shown in FIG.

In this case, the data corresponding to the output of the detection circuit 73 in the state where the original is not sandwiched during normal use is set by the switch 201 at the time of unpacking the setting or at the time of factory shipment. The output of the detection circuit 73 is A /
The digital data is converted by the D converter 74 into the comparator 20.
2 is always input. The CS terminal of the comparator 202 is connected to the output of the AND circuit 203. The AND circuit 203 has an interrupt signal from the control unit 61 and an I signal.
/ O read signal is supplied.

That is, the output of the comparator 202 is sent to the control unit 61 only when the interrupt signal from the control unit 61 and the I / O read signal occur simultaneously.

With this arrangement, the control section 61 can detect the open / closed state of the automatic document feeder 20 at any time when other processing is not performed.

[0229]

As described above in detail, according to the present invention,
By using a belt-shaped separating section having pressure-sensitive conductive rubber or using a feeding / rotating means having a pressure-sensitive conductive rubber facing the separating section, a change in the thickness of the document is converted into an electric signal. By detecting the feeding, it is possible to surely detect the double feeding of the originals, to detect the image reading operation or the image forming operation immediately after the double feeding, and to provide the paper sheet feeder which can easily recover.

By applying the separating means, the double feeding can be detected immediately after the occurrence of the double feeding, so that the recovery after the occurrence of the problem becomes possible immediately.

When the pressure-sensitive conductive rubber is used in the separating portion for separating the paper sheets by giving a frictional force to the paper sheets fed by the feeding rotary member, the separation function is deteriorated due to abrasion. It is possible to effectively prevent a decrease in double feed detection capability.

By adopting a structure in which the pressure-sensitive conductive rubber is used for the rotating body to detect the thickness of the paper sheet, it is not necessary to provide an electrode for signal detection in the paper sheet conveyance path. Therefore, paper feeding,
It is possible to ensure the stability of the separation function.

By forming a pressure-sensitive conductive rubber between a conductive member and a conductive layer, a change in resistance value due to a displacement amount of pressure applied to a rotating body is converted into a voltage or current value, so that paper sheets can be obtained. It is possible to detect the maximum amount of change in the thickness. This is because the direction of change in resistance of the pressure-sensitive conductive rubber is the same as the direction of pressure.

Further, by using the rotating body having such a structure, the signal detection is performed by a member for supporting the rotation of the conductive member and an electrode contacting the conductive layer at a position different from the separation position of the paper sheet. Can be done at. Therefore, the separation / feeding function is not affected.

The coefficient of friction between the conductive layer of the feeding rotary member and the paper sheet is μ _P0 , the coefficient of friction between the paper sheet and the paper sheet is μ _PP , and the friction coefficient between the surface of the separating rotary member and the paper sheet. Μ _P1 > μ _P0 > μ _P1
It is characterized by satisfying the> μ _PP relationship. When the pressure-sensitive conductive rubber is used for the separating rotary body, the friction coefficient between the conductive layer of the feeding rotary body and the paper sheet is μ _P2 , and the friction coefficient between the surface of the feeding rotary body and the paper sheet is μ _P0 . Then, the relationship of μ _P2 > μ _P0 > μ _PP is satisfied.

By setting the friction coefficient of the conductive layer to the above condition, a reliable separating operation becomes possible. If the conductive layer satisfies this condition, it is not necessary to further dispose the friction member coaxially or concentrically with the conductive layer, and it is possible to downsize the separating means and reduce the manufacturing cost of the feeding rotary member.

By forming the conductive layer by thick film printing using a conductive ink mixed with conductive particles, a stable signal can be obtained without peeling from the conductive layer as an electrode in the bent portion of the rotating body and the pressure-sensitive conductive rubber. It becomes possible to detect. When the conductive layer is made of a flexible substrate, an aluminum-bonded mylar, or the like, the above problem occurs. Further, the frictional force against the paper sheets necessary for separating / feeding the paper sheets is insufficient, and the separating operation becomes difficult.

Since the thickness of thick film printing is 10 to 15 μm, even when the conductive layer is covered with a part of the pressure-sensitive conductive rubber of the rotating body, the thickness of a normal paper sheet is 50.
Since the thickness is up to 150 μm, the step between the conductive layer and the pressure-sensitive conductive rubber layer is sufficiently small, and the separation function and the double feed detection function are not affected.

Since the conductive layer is formed by printing, the rotating body can be manufactured at low cost.

When the conductive layer is made of conductive rubber, the coefficient of friction with the paper sheet is high and the abrasion resistance can be improved as compared with the case where the conductive layer is formed by conductive ink.

By detecting the signal from the pressure-sensitive conductive rubber from the conductive layer by the conductive rotating body rotating in contact with the conductive layer, abrasion of the conductive layer of the feeding rotating body can be minimized. This ensures the reliability of the separation function and the signal detection function.

Further, by detecting the signal from the conductive member through the bearing, it is possible to surely detect the signal without providing an electrode.

Signal detection is performed by a conductive brush arranged so as to be in contact with the conductive layer to clean the paper dust and dust of paper sheets attached to the conductive layer by the function as an electrode and separation or feeding. It can also serve as a function. With this cleaning function, the initial frictional force can be maintained and the deterioration of the separating or feeding function can be suppressed to a minimum. Further, it is possible to solve the problem that the pressure locally changes due to the adhesion of dust and causes the malfunction of the double feed detection.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of a copying machine as an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of a document scanning unit.

FIG. 3 is a diagram for explaining a document conveying operation.

FIG. 4 is a block diagram schematically showing a configuration of a control circuit of the image forming apparatus.

5A and 5B are a perspective view and a cross-sectional view for explaining a configuration example of a separation unit.

FIG. 6 is a cross-sectional view showing a structure of a separation unit and a peripheral structure thereof.

FIG. 7 is a perspective view for explaining a configuration example of a separation unit.

FIG. 8 is a perspective view for explaining another configuration example of the separation unit.

FIG. 9 is a perspective view for explaining another configuration example of the separation unit.

FIG. 10 is a diagram showing the relationship between the pressure of the pressure-sensitive conductive rubber and the output voltage of the detection circuit.

FIG. 11 is a diagram showing a relationship between a typical pressure and a resistance value of pressure-sensitive conductive rubber.

FIG. 12 is a diagram showing a relationship between a typical pressure of a pressure-sensitive conductive rubber and a resistance value.

FIG. 13 is a cross-sectional view showing a structure of a separation roller and a peripheral structure thereof.

FIG. 14 is a cross-sectional view showing the structure of a separation roller.

FIG. 15 is a circuit diagram showing a schematic configuration of a detection circuit.

FIG. 16 is a block diagram showing a schematic configuration of a thickness detection circuit.

FIG. 17 is a timing chart for explaining an operation of a main part of the thickness detection circuit.

FIG. 18 is a diagram for explaining a separated feeding state of a document.

FIG. 19 is a diagram for explaining a separated and fed state of a document.

FIG. 20 is a flowchart for explaining a double-feed detection operation when a document is separated and fed.

FIG. 21 is a flowchart for explaining a double-feed detection operation at the time of separating and feeding a document.

FIG. 22 is a flowchart for explaining a double-feed detection operation when a document is separated and fed.

FIG. 23 is a flowchart for explaining a double-feed detection operation when a document is separated and fed.

FIG. 24 is a flowchart for explaining a double-feed detection operation when a document is separated and fed.

FIG. 25 is a flowchart for explaining a double-feed detection operation when a document is separated and fed.

FIG. 26 is a block diagram showing a schematic configuration of a thickness detection circuit.

FIG. 27 is a block diagram showing a schematic configuration of a thickness detection circuit.

FIG. 28 is a view for explaining sampling timings in a document separate feeding state.

FIG. 29 is a block diagram showing a schematic configuration of a thickness detection circuit.

FIG. 30 is a block diagram showing a schematic configuration of a peak detection circuit.

FIG. 31 is a timing chart for explaining an output timing of a latch clock with respect to a sampling pulse.

FIG. 32 is a diagram for explaining output signals from the detection circuit in three states (conditions) for the separation brake.

FIG. 33 is a block diagram showing an example of a detection circuit of an open / closed state of the automatic document feeder.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Copier main body O ... Original document 20 ... Automatic original feeder 25 ... Paper supply path 31 ... Separation roller 33 ... Separation section 253 ... Separation belt 253b ... Pressure-sensitive conductive rubber 51 ... Main control section 52 ... Operation panel 61 ... Control section 73 ... Detection circuit 74 ... A / D converter 76 ... Thickness detection circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03G 15/00 107 8530-2H

Claims (6)

[Claims] 1. A storage means for storing a plurality of paper sheets, a transport means for transporting the paper sheets, and a paper sheet stored in the storage means is taken out one by one and supplied to the transport means. Take-out means, a feed rotation means provided on the conveying means for feeding the paper sheets taken out by the take-out means, and a rotation direction of the feed rotation means that is in contact with the feed rotation means. And a separating means for separating the second and subsequent paper sheets taken out by the taking-out means from the first paper sheet by rotating in the opposite direction to the above-mentioned separating means. Paper which is constructed by laminating a pressure-sensitive conductive rubber whose resistance value changes according to the applied pressure and a conductive material provided outside the conductive rubber, and which is fed between the feeding rotation means. The pressure due to the feeding of the leaves is adjusted by the pressure-sensitive conductive rubber. Paper sheet feeding device characterized in that is output as reduction. 2. The separating means is formed in a belt shape in which a pressure-sensitive conductive rubber and a conductive material provided outside the conductive rubber are laminated. The paper sheet feeder described. 3. The coefficient of friction between the feeding and rotating means and the paper sheets is the largest, the coefficient of friction between the separating means and the paper sheets is the second largest, and the friction coefficient between the paper sheets is the largest. The paper sheet feeder according to claim 1, which is small. 4. A storage means for storing a plurality of paper sheets, a conveying means for conveying the paper sheets, and a paper sheet stored in the storage means is taken out one by one and supplied to the conveying means. A take-out means, a feeding / rotating means provided on the conveying means for feeding the paper sheets taken out by the take-out means, and a pressure-sensitive conductive rubber whose resistance value is changed by the applied pressure. Having, abutting against the feeding rotation means, by rotating in a direction opposite to the rotation direction of the feeding rotation means,
Separation means for separating the second and subsequent paper sheets taken out by the take-out means from the first paper sheet, and a change in resistance value due to the pressure-sensitive conductive rubber in the rotary feeding means. The separation means comprises: first detection means for detecting a corresponding electric signal; and second detection means for detecting a conveyance state of the paper sheet based on the electric signal detected by the first detection means. However, a pressure-sensitive conductive rubber whose resistance value changes depending on the applied pressure and a conductive material provided outside the conductive rubber are laminated, and are fed between the feeding rotation means. A paper sheet feeder, wherein the pressure associated with the feeding of the paper sheet is output as a change in resistance value by the pressure-sensitive conductive rubber. 5. The paper sheet feeding apparatus according to claim 4, wherein the second detecting means detects double feeding of the paper sheets as a conveyance state of the paper sheets. 6. A storage means for storing a plurality of paper sheets, a conveying means for conveying the paper sheets, and a paper sheet stored in the storage means is taken out one by one and supplied to the conveying means. Take-out means, a feed rotation means provided on the conveying means for feeding the paper sheets taken out by the take-out means, and a rotation direction of the feed rotation means that is in contact with the feed rotation means. And a separating means for separating the second and subsequent paper sheets taken out by the taking-out means from the first paper sheet by rotating in the opposite direction to the feeding rotation means. , A pressure-sensitive conductive rubber whose resistance value is changed by the applied pressure on the conductive member, and a conductive material provided outside the conductive rubber are concentrically arranged, and the separation means The pressure that accompanies the feeding of paper sheets fed between Paper sheet feeding device characterized in that the conductive rubber is output as a change in resistance value.