JPH0627763A - Automatic document feeder and copying system with it - Google Patents

Abstract

PURPOSE:To realize a copying system of high productivity and low cost capable of easily detecting completion of a bunch of documents at fast timing even when stop position of the documents is made at a standard on the front side, not complicated in structure and having an automatic document feeder and a device of a high carrying property and low cost. CONSTITUTION:A document setting sensor 28 is provided to detect existence of documents of a document loading table 21, an optical reflection type sensor 31 to detect existence of the document of the document loading table 21, and an MPU is provided to control the optical reflection type sensor 31 to move to a position to detect the rear end part of the documents at the time when the document setting sensor 28 detect existence of the documents on the document loading table 21 in accordance with detection information from the document setting sensor 28 and the optical reflection type sensor 31.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic document feeder and a copying system having the device, and more specifically, it separates documents one by one from a document stack placed on a document table and sequentially exposes the documents. The present invention relates to an automatic document feeder that is configured to convey a document to a position and expose the document at the exposure position, and then discharge the document to a document discharge table, and a copying system having the device and capable of performing high-speed copying.

[0002]

2. Description of the Related Art Recently, in a copying system such as a copying machine, there is a tendency that the speed is further increased, and various high speed copying systems have been announced. In this copying system, normally, a document is separated from a stack of documents placed on a document mounting table and sequentially conveyed to a document exposure position, and after the document is exposed at the exposure position, the document is ejected. It is equipped with an automatic document feeder (hereinafter, also simply referred to as ADF) that discharges paper to a table, and in a copying system equipped with this ADF, it is possible to shorten the document replacement time and how quickly. Whether or not the end of the document stack can be detected is an important point for increasing the speed of copying.

In order to shorten the time for replacing the original, the original transporting distance is shortened by setting the original stop reference on the original placing table to the front side, that is, the original feeding side. It is suitable above. However, this front standard A
In the DF, since the next original is always present at the original set detection position, the end of the original bundle is detected only after the feeding of the final original is started.

Usually, in a high-speed copying system, it is often after starting feeding of a transfer sheet corresponding to the next original (the original next to the final original) at this point, so this front side reference is used. Then, there was a problem that a blank copy with nothing copied might be made.
On the other hand, in some ADFs, the document stop position is set to the back side, that is, the discharge side reference. As the back side reference, for example, JP-A-58-88767 and JP-A-3-256949. There is one as described in the official gazette.

In the former publication, two sets of endless belts for feeding an original to the exposure position, that is, the back side on the contact glass are provided in front and behind in the feeding direction of the original. By controlling the belts separately, the next original is conveyed to the front side of the starting original. Further, in the latter publication, a mechanism for bringing the endless belt near the original document feeding side into contact with and separating from the contact glass is provided, and the original document is placed at the reference position on the back side of the contact glass. In such a case, the endless belt is separated upward from the contact glass so that the next original is conveyed and waits to the front side of the starting original.

In the conventional example described above, since the stop position of the originals is used as the back side reference, it is possible to detect the end of the original bundle at a relatively early time. In addition to the above, there is an advantage that it is possible to shorten the time for replacing the document.

[0007]

However, in the copying system having such a conventional automatic document feeder, two sets of endless belts are provided, or the endless belts are contacted with the contact glass. Since a mechanism for contacting and separating is provided, there is a problem that not only the mechanism becomes complicated, but also the cost increases.

Therefore, the present invention can easily detect the end of the document stack at an early timing even if the stop position of the document is used as the front side reference, the structure is not complicated, and the transportability is high and the cost is low. An object of the present invention is to provide a transporting device and a highly productive and low-cost copying system having the device.

[0009]

The invention according to claim 1 is
In order to solve the above-mentioned problems, originals are separated one by one from a bundle of originals placed on an original placing table, sequentially conveyed to an original exposure position, and after the originals are exposed at the exposure position, the original is ejected. In an automatic document feeder that discharges paper to a table, a document set sensor that detects the presence or absence of a document on the document table,
An optical reflection type sensor that is provided so as to be movable in the document feeding direction and detects the presence or absence of a document on the document placing table, and a document set sensor based on the detection information from the document set sensor and the optical reflection type sensor. And a reflection type sensor conveyance control means for controlling the optical reflection type sensor to move to a position where the rear end of the document is detected when the presence of the document on the document placing table is detected. It has a feature.

In order to solve the above-mentioned problems, the invention according to claim 2 has a light receiving element for receiving the light emitted from the optical reflection type sensor, and the light receiving element is arranged at a predetermined position, and the control means is provided. However, it is characterized in that whether or not the optical reflection type sensor is at the home position is determined based on the output information of the light receiving element. In order to solve the above-mentioned problems, a third aspect of the present invention is a copying system having the automatic document feeder according to the first or second aspect, wherein the exposure device exposes a document stopped at an exposure position, and the exposure unit. The automatic document feeder includes image forming means for forming the image exposed by the means on the transfer sheet, conveying means for conveying the transfer sheet to the image forming means, and conveying control means for controlling the operation of the conveying means. The apparatus conveys the original document to the exposure position and starts feeding the next original document while the original document is exposed by the exposure means. When it is detected that the original has been fed and is not on the original placing table, the next original is determined to be the final original, and the conveyance control unit conveys the next transfer paper of the transfer paper corresponding to the next original. Characterized by communicating that it will be canceled That.

[0011]

According to the first aspect of the present invention, a document set sensor for detecting the presence or absence of a document on the document table and a document set sensor movably provided in the document feeding direction to detect the presence or absence of the document on the document table. When the document set sensor detects that there is a document on the document mounting table based on the detection information from the optical reflection type sensor and the document set sensor and the optical reflection type sensor, the optical reflection type sensor detects the document Reflective sensor control means for controlling the rear end to move to a position for detection.

Therefore, the original is surely detected regardless of the size of the original. In addition, the optical reflection type sensor is moved to the rear end of the document to reliably detect the rear end of the document,
At this time, substantially at the same time as the final document is fed, it is surely detected that the document is the final document. As a result,
Even if the stop position of the document is the front side reference, the end of the document stack is detected at an early timing, the structure is simplified, and a low-cost automatic document feeder having high transportability can be obtained.

According to another aspect of the present invention, there is provided a light receiving element for receiving the light emitted from the optical reflection type sensor, the light receiving element is arranged at a predetermined position, and the reflection type sensor control means outputs the output information of the light receiving element. Based on the above, it is determined whether or not the optical reflection type sensor is at the home position. Therefore, by using the reflective sensor itself, the home position of the reflective sensor can be easily detected, and the reflective sensor can be controlled at low cost.

According to the third aspect of the present invention, while the original document is conveyed to the exposure position by the automatic document feeder and the original document is exposed by the exposure means, the feeding of the next original document is started, and the optical system is operated. When the reflective sensor detects that the next original is fed and is not on the original placing table, the reflective sensor control means determines that the next original is the final original, and at this time, the conveyance control is performed. The means for stopping the conveyance of the next transfer sheet of the transfer sheet corresponding to the next original is transmitted to the means.

Therefore, the next original is fed immediately after the feeding of the first original, which shortens the time for replacing the original.
Further, when the next original is the final original and the rear end of the original is detected by the reflection type sensor, the transfer paper is stopped at an early timing, and a blank transfer paper is generated as in the conventional case. To be done. In addition, high-speed copying can be performed at low cost without complicating the structure.

[0016]

EXAMPLES The present invention will be described below based on examples.
1 to 8 are views showing an embodiment of a copying system having an automatic document feeder according to the present invention. First, the configuration will be described. FIG. 1 is a diagram showing an outline of a copying system of the present invention. In FIG. 1, reference numeral 1 is an ADF, and the ADF 1 is composed of a paper feed unit 2, a transport unit 3 and a paper discharge unit 4, and is not shown. It covers the contact glass 5 provided on the upper part of the main body of the copying machine.

An exposure unit 6 is provided below the contact glass 5.
The exposure means 6 is composed of a light source 7, a plurality of reflection mirrors 8 and a lens 9 and the like, and exposes the original document conveyed on the contact glass 5 from the right side in the drawing. A photosensitive drum 10, which is an image carrier, is disposed below the exposing means 6, and a known charger (not shown) is provided around the photosensitive drum 10.
A developing device, a transfer charger, a cleaning device and the like are provided, and when the exposure light L corresponding to the original image from the exposure means 6 is irradiated onto the photoconductor drum 10, the exposure light L
Is formed as an electrostatic latent image, the electrostatic latent image is visualized and then transferred onto a transfer paper.
The photoconductor drum 10, the charger, and the like form an image forming unit 11.

Further, 12 is a transfer paper cassette, and a plurality of transfer papers 13 are stored in this transfer paper cassette 12.
The transfer paper 13 is fed at the uppermost position by a calling roller 14, and then conveyed by a paper feeding roller 15 and a reversing roller 16 which face each other, and then a registration roller 17
The sheet is conveyed below the photoconductor drum 10 while being timed by. The transfer charger described above is disposed below the photoconductor drum 10, and the transfer paper is designed to transfer a visible image while passing between the photoconductor drum 10 and the transfer charger.

After the transfer, the transfer paper is moved to a fixing roller 18 to fix the visible image by the roller 18, and then discharged by a paper discharge roller 19 to a paper discharge tray (not shown). The calling roller 14, the sheet feeding roller 15, the reversing roller 16 and the registration roller 17 described above constitute a conveying unit that conveys the transfer sheet to the image forming unit 11. ADF
As shown in FIGS. 2 to 5, the sheet feeding unit 2 of 1 has a document placing table 21 on which the document stack P can be placed, and the document placing table 21 is slit along the document feeding direction. 21a is formed (shown by hatching in FIG. 1). Call rollers 22 and 23 are provided in front of the document table 21, and the call rollers 22 and 23 feed a bundle of documents.

A separation roller 24 is provided in front of the calling roller 23.
And a separating blade 25 are provided for this roller 24
The blade 25 separates the lowermost originals from the original stack P one by one and feeds them. The separated originals are directed to the contact glass 5 by the pull-out driving roller 26 and the pull-out driven roller 27. It is designed to be transported.

These calling rollers 22, 23, separation rollers
The driving roller 26 and the driving roller 26 are connected to an M ₁ motor 101 capable of rotating in the forward and reverse directions via a plurality of clutches (not shown).
It is driven by this motor 101. Further, a position encoder (not shown) is provided at the end of the rotary shaft of the calling roller 23, and this encoder is provided with a one-rotation detecting sensor 110. The M ₁ motor 101 uses the output information from the one-rotation detecting sensor 110. It is designed to rotate forward and backward.

Then, the M ₁ motor 101 drives the calling rollers 22, 23, the separation roller 24 and the drive roller 26 at the time of reverse rotation to separate the document bundle P one by one and feed it.
At the time of forward rotation, the clutches connected to the calling rollers 22, 23 and the separation roller 24 are idled to stop the rollers 22 to 24, and only the roller 26 is operated so that the original is contacted with the contact glass 5
To transport. Therefore, the following document is not separated during normal rotation.

A document set sensor is provided near the separation blade 25.
28 and a detection filler 29 are provided. The detection filler 29 is swingable around a fulcrum, and when the bundle of documents P comes into contact with the leading end, it moves upward as shown by the solid line. The set sensor 28 is composed of a photo interrupter, and when the filler 29 moves upward, the filler 29
It is detected that the optical path is no longer blocked by the
Is set to be detected. A registration sensor 30 is provided in front of the rollers 26 and 27, and the sensor 30 detects a document.

On the other hand, an optical reflection type sensor 31 is provided below the slit 21a portion of the document placing table 21, and this sensor 31 is attached to an endless timing drive belt 32. The timing belt 32 is wound around pulleys 33 and 34, and this pulley 34 is driven by a step motor (hereinafter, also simply referred to as M ₂ motor) 102. Therefore, the sensor 31 can detect the presence or absence of the document through the slit 21a by moving the lower part of the slit 21 along the document feeding direction as shown by the arrow by the belt 32.

A home position sensor (hereinafter, also simply referred to as an HP sensor) 35, which is composed of a phototransistor and constitutes a light receiving element, is provided below the document placing table 21, and the sensor 35 emits light from the sensor 31. Is received to detect whether the sensor 31 is at the home position. An endless conveyor belt 41 is provided in the conveyor unit 3 of the ADF 1, and the conveyor belt 41 is wound around a driving roller 42 and a driven roller 43. Drive roller
42 is driven by the M ₃ motor 103, and conveys the document separated and fed by the paper feed unit 2 to the exposure position on the paper feed unit 2 side of the contact glass 5 and stops it. ing.

The sheet discharging section 4 of the ADF 1 has a reversing roller 45, a sheet discharging roller 46, a sheet discharging sensor 47, etc., which are driven by the M ₄ motor 104. The document on the contact glass 5 is discharged onto a document discharge tray (not shown). Further, the paper discharge sensor 47 is adapted to detect that the document has been discharged.

Further, a reversing switching claw (not shown) is provided on the downstream side of the reversing roller 45 in the document discharging direction, and the switching claw is driven by a reversing solenoid to discharge the document as it is onto the document discharging tray. Either a paper path or a reversal path (not shown) for returning to the contact glass 5 is selectively switched. Also, 51 is A
It is an MPU consisting of a one-chip microcomputer that controls the entire DF1, and this MPU 51 is connected to the control unit 52 of the main body of the copying machine via an interface driver 53, so that information is transmitted by serial communication. There is.

The MPU 51 drives each of the motors M _{1 to} M ₄ based on the output information from the various sensors such as the sensors 28, 30, 31, 35, 47 and 110 input via the input buffer 54. ing. Each motor M _{1 to} M ₄ is a driver 105
~ 108, each driver 105 ~ 108 receives a command from the MPU51, each motor M.
Rotation speed of 1 to M ₄ and forward / reverse rotation control are performed.

The MPU 51 activates the motor M ₂ especially when the document set sensor 28 detects that the document stack P is on the document table 21 based on the output information of the document set sensor 28 and the reflection type sensor 31. By driving, the timing belt 32 is operated to control the optical reflection type sensor 31 to be moved to a position where the rear end of the document is detected. There is.

Further, the MPU 51 judges whether or not the reflection type sensor 31 is at the home position based on the output information of the HP sensor 35, and controls the motor M ₂ based on this sensor information. On the other hand, the driving of the calling roller 14, the paper feeding roller 15, the reversing roller 16 and the registration roller 17 provided in the copying machine body is controlled by the control unit 52. Then, the paper feed section 2 starts feeding the next original while the original is conveyed to the exposure position on the contact glass 5 and the original is exposed by the exposure means 6. At this time, the MPU 51 determines that the next original is the final original when the reflective sensor 31 detects that the next original is fed and is not on the original placing table 21, and sends a signal to the controller 52. It is designed to communicate. Upon receiving this signal, the control unit 52 immediately stops the operation of the calling rollers 14 and the like, and performs control to stop the conveyance of the transfer sheet next to the transfer sheet corresponding to the next original.

For controlling the speed of the motor in the drivers 105 to 108, an encoder 120 mounted on the motor is used.
Pulses from .about.122 are used, and further, this pulse information is supplied to the MPU 51, and the MPU 51 mainly controls the position of the document based on this pulse information. In addition to this, a part of this pulse information is also used for motor abnormality detection.
Further, the MPU 51 controls various solenoids 56 such as the above-mentioned switching solenoid via the solenoid driver 55.

Next, the operation of the copying system provided with the ADF 1 of this embodiment will be explained based on the flow charts shown in FIGS. 6 and 7 and the timing chart shown in FIG. Figure 6
7 is a flowchart showing the overall operation of ADF1, FIG.
Is a flow chart of the trailing edge detecting and moving process of the document, and M
It is executed by PU51. FIG. 8 shows an A4 size original 3
7 is a timing chart of ADF1 when sheets are set.

Before explaining this operation, it is assumed that the operating conditions of the copying system are set as follows. (1) Copy speed A4 size 80 CPM (Copy / Minute)
And (2) The process speed of the copier body is 490 mm / s. In this way, the time required to expose a 210 mm size A4 landscape is 210/490 = 429 ms. (3) After the copying machine starts separating and feeding the transfer paper 13, aligns the leading edge of the transfer paper 13 with the registration roller 17, and then transfers the visible image leading edge on the photosensitive drum 10 (see FIG. 1) Distance indicated by ab)) Required time is 1589 ms. (4) The exposure of the original image by the exposure means 6 starts 159 ms before (3).

As a result of the above, in order to satisfy 80 CPM,
As shown in FIG. 8, it is necessary to start the transfer paper 13 during the exposure of the original two sheets before, and the original feeding speed is 1500 mm / s,
The time required for separating the document bundle P is 80 ms, and 120 ms is required until the document stack P is conveyed to the contact glass 5 and stopped after the separation. The operation of the high-speed copying system under the above conditions will be described.

In FIG. 6, first, in step S1, it is determined based on the output information from the set sensor 28 whether or not a document (A4 size) is set. At this time, when it is determined that the document is set, the detection filler 29 moves upward as shown by the solid line in FIG.
It is judged from the fact that the optical path is blocked and the set sensor 28 is turned on.

When the original is set, the process goes to step S2 to send a message to that effect to the control unit 52, and then goes to step S3 where the reflective sensor 31 detects that the HP sensor 35 has detected the output information from the HP sensor 35. Determine if you are in the home position below 35. If it is not at the home position, the process proceeds to step S4 and the M ₂ motor 102 is operated to move the sensor 31 to the home position.

On the other hand, if it is determined in step S3 that the vehicle is in the home position, the flow advances to step S5 to execute the trailing edge detection movement processing flow shown in FIG. Here, first, in step S51, the M ₂ motor 102 is operated in one direction to move the reflective sensor 31 in the CW direction, that is, from the home position to the downstream side in the document conveying direction. Therefore, the reflective sensor 31 moves while detecting the document through the slit 21a.

Next, in step S52, the HP sensor
It is determined whether or not 35 is turned off. In this case, since it is turned off, the process proceeds to step S53, and it is determined whether or not the reflection type sensor 31 detects the document. If it is determined that the document has not been detected, it is determined that the reflective sensor 31 has moved from the rear end of the document to the downstream side and turned off. Therefore, the process proceeds to step S54 and the reflective sensor 31 is operated. Is O
When the FF is performed (the time indicated by c in FIG. 8), that is, the document is moved downstream from the trailing end of the document by a predetermined amount (x pulses).

Next, in step S55, it is determined whether or not the reflection type sensor 31 has advanced x pulses, and if so, the process proceeds to step S56, in which the M ₂ motor 102 is driven in the other direction and the reflection type sensor 31 is driven. 31 is moved in the CCW direction. Next, in step S57, it is determined whether or not the reflection type sensor 31 has detected the trailing edge of the document again. If it is determined that the rear edge of the document has been detected, the operation proceeds to step S58 to operate the M ₂ motor 102. Stop. Therefore, the reflection type sensor 31 stands by while detecting the trailing edge of the document.

When this process ends, step S6
Then, it is judged whether or not there is a paper feed command from the control unit 52, and if there is, it is judged that a start switch (not shown) of the main body of the copying machine has actuated, and the routine proceeds to step S7.
Pre-feeding, that is, it is determined whether or not the next original is fed immediately after the starting original is fed. If the pre-feeding is not performed, the process proceeds to step S8.

The paper feeding operation for the first original will be described in parallel with the flow of pre-paper feeding from the order of paper feeding operation. In step S8, the motor M ₁ is rotated in the reverse direction so that the rollers 22, 2
Activate 3, 24 and 26. Therefore, the document stack P is fed between the separation roller 24 and the blade 25, and the document at the lowest position is separated. The pre-feeding is performed at the timing during the exposure operation.

Next, in step S9, it is determined whether or not the calling roller 23 has made one rotation based on the output information from the one-rotation detection sensor 110. When it is determined that it has made one rotation, the process proceeds to step S10 and M ₁ The driving of the motor 101 is stopped. On the other hand, if one rotation is not detected, the process proceeds to step S11, where it is determined whether or not the reflection type sensor 31 is turned off. In this case, the feeding of the first document is just started. Therefore, the process proceeds to steps S9 and S10.

On the other hand, if the pre-feeding is completed in step S7, the flow advances to step S13 to start feeding and conveying the original. At this time, the M ₁ motor 101 is driven in the normal direction and the M ₃ motor 103 is driven. When the M ₁ motor 101 is driven in the forward direction, the clutch causes the calling roller 22,
Since the 23 and the separation roller 24 idle, the document is nipped by the separation and driven rollers 26 and 27, and at the same time the transport belt is conveyed.
It is conveyed toward the contact glass 5 by 41.

Next, in step S14, it is determined whether or not the trailing edge of the document has passed the registration sensor 30, and if it has passed, a predetermined time is determined from the time when the trailing edge of the document passes the registration sensor 30. After driving the M ₃ motor 103 for only a pulse, the M ₃ motor 103 is stopped. Therefore, the document stops at the exposure position on the contact glass 5. Next, in step S16, it is determined whether or not there is a document on the document table 21, and if there is a document, the process proceeds to step S8 to pre-feed the next document. If the above-described pre-feeding is performed when the first original is stopped on the contact glass 5, the next original is fed to the lower part of the registration sensor 30. On the other hand, if there is no document, step S17
In step S6, the fact that the original has not been set is transmitted, and the flow advances to step S6.

On the other hand, if the paper feed command is not started in step S6, the process proceeds to step S20, it is determined whether or not the paper discharge command is issued, and if the paper discharge command is issued,
Since it is determined that the exposure operation of the original has been completed by the exposure means 6 on the contact glass 5, a signal is input from the control unit 52 at the end of the exposure operation (at the timings indicated by d, e, and f in FIG. 8). It

[0046] In this case, M ₃ proceeds to step S21, M ₄
Driving the motors 103 and 104, the conveyor belt 41 and the reversing roller 4
The document is discharged by 5 and the discharge roller 46. Also,
At this time, since the next original has been pre-fed, the carrying flow of steps S7 and S13 is executed thereafter. on the other hand,
At the time of paper ejection, the rear end of the document is ejected by the paper ejection sensor 47 in step S22.
It is determined whether or not the document has passed, and when it has passed, it is determined that the document has been discharged, and the process proceeds to step S23, where M ₃ ,
After stopping the operation of the M ₄ motors 103 and 104, step S24
Then, it is determined whether or not a document is set on the document placing table 21, and if it is set, the process proceeds to step S6 to execute the subsequent processing, and if not, step S6.
Proceed to step 25 and send a message that there is no original.

On the other hand, if the one-rotation detection sensor 110 has not detected one rotation in step S9 during pre-feeding,
That is, when the reflective sensor 31 is turned off in step S11 while the original is being fed by the calling roller 22, the reflective sensor 31 located at the rear end of the fed original is turned off. In order to detect that this document is the final document (at the time indicated by g in FIG. 8), the process proceeds to step S12.

Then, in step S12, the fact that this original is the final original is transmitted to the controller 52. At this time, the control unit
52 controls the calling roller 14 and the like so as to stop the conveyance of the next transfer sheet of the transfer sheet corresponding to this final document. As described above, in the present embodiment, the document set sensor 28 for detecting the presence / absence of a document on the document table 21 and the optical type sensor for detecting the presence / absence of a document on the document table 21 are provided so as to be movable in the document feeding direction. When the document set sensor 28 detects that there is a document on the document table 21 based on the detection information from the reflection type sensor 31, the document setting sensor 28, and the optical reflection type sensor 31, the optical reflection type sensor An MPU 51 that controls to move 31 to a position where the trailing edge of the document is detected is provided.

Therefore, the original can be reliably detected regardless of the size of the original. Further, the reflection type sensor 31 can be moved to the rear end portion of the document to reliably detect the rear end portion of the document. At this time, at the same time as feeding the final document, the document is the final document. It can be reliably detected that there is. As a result, even if the stop position of the document is the front side reference, the end of the document stack can be detected at an early timing, and the structure can be simplified and the ADF 1 having high transportability can be obtained.

On the other hand, in the case where the reflection type sensor 31 is not provided, the trailing edge of the original must be detected only by the set sensor 28. Since the set sensor 28 is interlocked with the detection filler 29, the return time of the filler 29 is required, and the trailing edge of the document can be detected only when the final document is fed. After passing through the registration sensor 30 for 10 to 20 ms (the time indicated by h in FIG. 8).

Even if the end of the original is transmitted to the control unit 52 at this timing, the next transfer sheet has already been started as shown by j in FIG. 8, and a blank transfer sheet is obtained. Become. The only way to eliminate this blank transfer paper is to slow down the copy speed (CPM), and the productivity of the copy work will be considerably reduced. In this embodiment, since the reflective sensor 31 is provided as described above,
The trailing edge of the document can be detected at an early stage, and such a problem does not occur.

Further, in this embodiment, the HP sensor 35 for receiving the light emission of the reflection type sensor 31 is provided, and the MPU 51 determines whether the reflection type sensor 31 is at the home position based on the output information of the HP sensor 35. Since the judgment is made, it is possible to easily use the reflection type sensor 31 by using the reflection type sensor 31 itself.
The home position can be detected, and the reflective sensor 31 can be controlled at low cost.

Further, in this embodiment, the ADF1
While the original is conveyed to the exposure position and is being exposed by the exposure means 6, the feeding of the next original is started, and the reflection type sensor 31 feeds the next original and sets it on the original table 21. If the MPU 51 determines that the next original is the final original when it is detected that the next original is not the final original, the MPU 51 instructs the control unit 52 to stop the conveyance of the next transfer of the transfer original corresponding to the next original. Trying to communicate.

Therefore, the next original can be fed immediately after the feeding of the first original, and the time required for exchanging the original can be shortened. Further, when the next original is the final original and the rear end of the original is detected by the reflection type sensor 31, the transfer paper can be stopped to be conveyed at an early timing. It is possible to prevent paper from being generated. Further, high-speed copying can be performed at low cost without complicating the structure.

[0055]

According to the first aspect of the present invention, the original can be reliably detected regardless of the size of the original. Further, the reflection type sensor can be moved to the rear end portion of the original document to reliably detect the rear end portion of the original document. At this time, at the same time as feeding the final original document, the original document is the final original document. This can be reliably detected. As a result, even if the stop position of the documents is the front side reference, the end of the document stack can be detected at an early timing, and the structure can be simplified and a low-cost automatic document feeder with high transportability can be obtained. it can.

According to the second aspect of the present invention, the home position of the reflective sensor can be easily detected by using the reflective sensor itself, and the reflective sensor can be controlled at low cost. According to the third aspect of the present invention, the next original can be fed immediately after the feeding of the first original, and the time required for exchanging the original can be shortened. Further, when the next original is the final original, when the rear end of the original is detected by the reflective sensor, the transfer paper can be stopped to be conveyed at an early timing. Can be prevented. Further, high-speed copying can be performed at low cost without complicating the structure.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an automatic document feeder according to the invention described in any one of claims 1 to 3 and a copying system having the device.

FIG. 2 is a configuration diagram of a sheet feeding unit of the automatic document feeder according to the embodiment.

FIG. 3 is a perspective view of an automatic document feeder according to an embodiment.

FIG. 4 is a configuration diagram of a moving mechanism of the reflective sensor according to the embodiment.

FIG. 5 is a schematic block diagram showing the overall circuit configuration of an automatic document feeder according to an embodiment.

FIG. 6 is a flowchart showing the overall operation of the automatic document feeder according to the embodiment.

FIG. 7 is a flowchart of a trailing edge detecting and moving process of a document according to an embodiment.

FIG. 8 is a timing chart of the automatic document feeder when three A4 size originals are set according to an embodiment.

[Explanation of symbols]

 1 ADF (automatic document feeder) 5 contact glass 6 exposure means 11 image forming means 13 transfer paper 14 calling roller (conveying means) 15 paper feeding roller (conveying means) 16 reversing roller (conveying means) 17 registration roller (conveying means) 21 Document Placement Table 28 Document Set Sensor 31 Optical Reflective Sensor 35 Home Position Sensor (Photosensitive Element) 51 MPU (Reflective Sensor Control Unit) 52 Control Unit (Conveyance Control Unit) P Document Bundle

Claims (3)

[Claims] 1. An original is separated from a bundle of originals placed on an original placing table and conveyed one by one to an original exposing position. After the original is exposed at the exposing position, the original is ejected to an original ejecting table. In an automatic document feeder designed for paper, a document set sensor that detects the presence or absence of a document on the document table, and a document that is movable in the document feed direction to detect the presence or absence of a document on the document table When the document set sensor detects that there is a document on the document mounting table based on the detection information from the optical reflection type sensor and the document set sensor and the optical reflection type sensor, the optical reflection type sensor detects the document An automatic document feeder, comprising: a reflection-type sensor control unit that controls to move the rear end portion to a detection position. 2. A light receiving element for receiving light emitted from the optical reflection type sensor, the light receiving element being arranged at a predetermined position, and the control means based on output information of the light receiving element. The automatic document feeder according to claim 1, wherein it is determined whether or not the sensor is at the home position. 3. A copying system having the automatic document feeder according to claim 1 or 2, wherein an exposing means for exposing an original stopped at an exposing position and an image exposed by the exposing means are formed on a transfer paper. Image forming means, and a conveying means for conveying the transfer paper to the image forming means,
The automatic document feeder conveys a document to an exposure position and feeds the next document while the document is being exposed by the exposure unit. When the optical reflection type sensor detects that the next original is fed and is not on the original placing table, the reflection type sensor control unit determines that the next original is the final original, A copying system having an automatic document feeder, which conveys to the feeding control means that the feeding of the next transfer sheet corresponding to the next original is stopped.