JPH09315618A - Automatic document conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an errneous of a preceding document by not performing jam detection until the rear end of the preceding document passes a read position in case the preceding document is passing the read position at the time of detecting that the tip of a succeeding document is in a specified position. SOLUTION: In case a document is being read, it is so judged that the document is passing slit glass, and whether a register sensor (tip detecting means) is off is discriminated (S4). In case the register sensor being off, whether the rear end of the document has passed a read position is discriminted on the basis of the pulse count value of a driving motor counted from the position of the register sensor (S7). In case of having passed, whether the register sensor is turned on again is discriminated (S8). In case of the register sensor being on, it is so judged that a succeeding document is conveyed in a somewhat jointly fed state, and the conveyance of the preceding document is continued without performing jam detection to make the document pass through the read position.

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 mounted on an image forming apparatus such as a copying machine or a facsimile machine, and more specifically, it separates an original from a plurality of original bundles at a reading position. The present invention relates to an automatic document feeder that conveys an image to a stopped image reading unit.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as a copying machine or a facsimile machine, when a document stack consisting of a plurality of documents is placed on a document table and a job start switch is pressed, one document is printed. An automatic document feeder is provided that separates the documents one by one and conveys them to the reading position, and reads the document by the reading means that stops at the reading position, and when this reading is completed, the document is discharged to a predetermined discharge position. There is something.

In recent automatic document feeders, in order to simplify the structure and reduce the cost, a single drive motor is exclusively used for a drive system for feeding an original. (See, for example, Japanese Patent Laid-Open No. 7-187429), a document is separated and conveyed to a reading position by a separating and conveying unit driven by a single drive motor, and then read by a sheet discharging unit driven by the drive motor. The document that has been read at the position is ejected. Further, in order to reduce the reading time of the original document, this device is configured to put the succeeding original document on standby at a predetermined position on the upstream side of the reading position while the preceding original document is being read. Is detected by a registration sensor.

By the way, since such an automatic document feeder has a single drive motor, it may follow the preceding document at the time of separation of the document, depending on the type of document and the use environment (temperature, humidity, etc.). When a document to be transported is conveyed with a little feeding, it is difficult to stop only the following document at a predetermined position and transport only the preceding document, so the trailing edge of the preceding document passes the reading position. When the leading edge of the following original is detected by the registration sensor before it is carried out, the conveyance of the original is stopped by detecting it as a feeding jam.

[0005]

However, in such a conventional automatic document feeder, the leading edge of the following document is detected by the registration sensor before the trailing edge of the preceding document passes the reading position. Then, since it was detected as a jammed paper feed and the document conveyance was stopped, the document that was being read normally even though the cause of the jam was the following document was stopped. Therefore, there is a problem that a miscopy occurs.

Therefore, according to the first aspect of the present invention, even when the original is conveyed with a little feeding, the preceding original is surely read to prevent the miscopy of the original. An object of the present invention is to provide an automatic document feeder capable of performing the above. According to the second aspect of the present invention, when the succeeding document is conveyed with a slight amount of conveyance and exceeds the stop position with respect to the predetermined position, the exceeded amount rises to the conveyance speed corresponding to the copy magnification to the reading position. When the distance is sufficient, the document start timing is delayed by the protrusion amount from the predetermined position so that the document is transferred to the reading position and copied at the same transfer start timing as when stopped at the stop position. An object of the present invention is to provide an automatic document feeder which can carry out smooth feeding control without causing interruption of feeding due to jam detection by feeding at a feeding speed according to the magnification.

[0007]

According to the first aspect of the present invention,
In order to solve the above-mentioned problems, the image forming apparatus is equipped with a reading unit stopped at the reading position, and the original is continuously conveyed to the reading position while the original is read by the reading unit. An automatic document feeder, which separates and conveys a bundle of documents placed on a document table to a reading position, a discharging unit which discharges a document that has been read, and the separating and conveying unit. And a single drive motor for driving the sheet discharging means, so that when a preceding document finishes reading, a document following this document is made to stand by at a predetermined position upstream of the reading position in the document conveying direction. In an automatic document feeder that drives the separation / conveyance unit and the paper discharge unit, a leading edge detection unit that detects that the leading edge of the document is at the predetermined position and a passage detection unit that detects that the document is at the reading position. Means and the detection signals from the leading edge detecting means and the passage detecting means, when it is detected that the leading edge of the succeeding document is at the predetermined position, the preceding document is preceded when it is passing through the reading position. It is characterized in that a control means is provided for driving the separating / conveying means and the paper discharging means without performing jam detection until the trailing edge of the document passes the reading position.

In this case, when the original document is conveyed with a little feeding, the distance between the preceding original document and the subsequent original document is short, and the subsequent original document stops at a predetermined position, the preceding original document passes through the reading position. If it is not, the jam detection is not performed until the trailing edge of the preceding document passes the reading position, so that the reading of the preceding document can be reliably performed, and a miscopy of the preceding document may occur. Can be prevented.

According to a second aspect of the present invention, in order to solve the above-mentioned problems, in the invention according to the first aspect, the control means sends a detection signal from the leading edge detection means when the preceding document passes the reading position. It is configured to count the protrusion amount of the leading edge of the following document from the predetermined position based on the above.When the protrusion amount of the following document is less than or equal to a predetermined value, the jam detection of the following document is not performed and the predetermined position is not detected. It is characterized in that the conveyance start timing of the original stopped at the above is delayed by the protrusion amount and the separation and conveyance means is re-driven.

In this case, when the succeeding document is conveyed with a slight amount of conveyance and exceeds the stop position with respect to the predetermined position,
When the excess amount is a distance sufficient to rise to the conveyance speed corresponding to the copy magnification to the reading position, the conveyance start timing of the document is delayed by the protrusion amount from the predetermined position and stopped at the stop position. The original is conveyed to the reading position at the same conveyance start timing as that described above, and is conveyed at a conveyance speed corresponding to the copy magnification.

That is, when reducing a copy of an original, the original conveying speed is increased and the original is read by the reading means. When enlarged copying of the original is performed, the original conveying speed is reduced and the original is read by the reading means. Read with. Therefore, if the leading edge of the document pops out from the stop position to the reading position by a predetermined amount or more when the document is reduced, the distance from the leading edge of the document to the reading position is shortened and the conveyance speed corresponding to the copy magnification rises. It's gone.

Therefore, when the amount of protrusion of the front end of the document from the predetermined position is a distance sufficient to rise to the conveyance speed corresponding to the copy magnification to the reading position, the conveyance start timing of the document from the predetermined position. By delaying by the protrusion amount, it is possible to convey the document to the reading position at the same conveyance start timing as when it apparently stopped at the stop position, and to convey at the conveyance speed according to the copy magnification, and jam detection Therefore, it is possible to perform smooth transfer control without interrupting the transfer.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are views showing an embodiment of the automatic document feeder according to the present invention, and show an example in which the automatic document feeder is attached to an image recording apparatus. The image reading device can be applied to a copying machine, a facsimile device and the like.

First, the structure will be described. In FIGS. 1 to 3, 1 is an image forming apparatus, and a slit glass (reading position) 2 and a contact glass 3 are provided on the upper surface of the image forming apparatus 1. Below the slit glass 2 and the contact glass 3, an exposure lamp 4 as an image reading means, a first mirror 5 and the like are provided. The exposure lamp 4 and the first mirror 5 are mounted on the contact glass 3. When reading an original document, it moves to the left and right in FIG. 1 below the contact glass 3, and when reading an original document on the slit glass 2, it stops below the slit glass 2 and the exposure lamp 4 After the original surface is read by, the reflected light is focused on a focusing element such as a CCD through a first mirror 5 and a lens (not shown) as is known.

Further, an automatic document feeder (hereinafter, simply referred to as ADF) 6 is mounted on the image forming apparatus 1, and a document placed on the contact glass 3 is placed on the lower surface of the ADF 6. A reflecting plate 7 is provided which is pressed against and serves as a white reference when reading a document.
The ADF 6 is connected to the image forming apparatus 1 via a hinge 8 as shown in FIG.
Can be opened and closed freely.

A document placing table 9 is provided on the upper part of the ADF 6, and a document stack P made up of a plurality of documents is placed on the document placing table 9. The original bundle P placed on the original placing table 9 contacts the original bundle P.
After being fed by the separable calling roller 10, the sheet is separated by a separation belt 11 and a separation prevention roller 12, and the separation belt 11 presses and contacts the separation prevention roller 12 at an arbitrary angle θ. ing.

A stopper member 13 is provided downstream of the calling roller 10 in the original conveying direction, and the original bundle P placed on the original placing table 9 is stopped by the stopper member 13 to the separating belt 11 side. It is forbidden to enter. Call roller
A pressure plate 14 is provided below the pressure plate 10.
The solenoid 100 comes into contact with and separates from the calling roller 10. That is, when the copy start switch is pressed down, the pressure plate 14 is operated by the solenoid 100.
Move from the position separated from the calling roller 10 indicated by the solid line to the position contacting the calling roller 10 indicated by the virtual line, press the document to the calling roller 10, and feed the document by the calling roller 10. Has become. It should be noted that this start switch is provided from the main body main controller 102 provided in the main body of the image forming apparatus 1 to the ADF main controller 101.
When the signal is output to the solenoid 100, the solenoid 100 is driven based on the output signal from the ADF main controller 101.

The separation belt 11 is bridged between a driving roller 15 and a driven roller 16, and the driven roller 15 is attached to a case 17 by a shaft 15a.
Are connected via The case 17 is rotatable about a shaft 15a.
10 are installed. Therefore, when the case 17 rotates about the shaft 15a as a fulcrum, the call roller 10 is separated from the document bundle P. When the driven roller 16 is rotated about the fulcrum 15a in this state, the separation belt 11 is separated from the separation preventing roller 12. The case 17 is connected to the paper feed unit case 18 via a shaft 15a, and the paper feed unit case 18 is rotatably attached to the ADF 6 main body via a fulcrum 19.

The driven roller 16 is biased by a spring 20, and the spring 20 separates the separation belt.
11 has a constant tension. Also, drive roller 15
A one-way clutch 21 connected to the drive motor 103 is provided between the shaft 15a and the shaft 15a, and the drive roller 15 is rotated clockwise by the clutch 21 in FIG.

The drive of the shaft 15a is transmitted to the calling roller 10 through a gap clutch (not shown). This gap clutch rotates the shaft 15a by a predetermined degree when the drive of the shaft 15a is transmitted, and then rotates the shaft 15a to the calling roller 10.
This is a member in which a meshing portion is formed so as to transmit the driving force of the document. Conversely, when the calling roller 10 is rotated by the conveyance of the document, the mesh for transmitting the driving force is disengaged. When the trailing edge of the trailing edge passes through the calling roller 10, the rotation of the shaft 15a is not transmitted to the calling roller 10 until it is rotated by a predetermined angle, and the interval between the following document and the original is opened during that time.

In order to exert such a function,
Instead of the gap clutch, the driving roller 15 and the calling roller 10 may be driven via an electromagnetic clutch or a spring clutch. The separation prevention roller 12 is shown in FIG.
It is designed to rotate in the middle and clockwise, and the separation belt
The uppermost document is separated from the document stack P fed between 11 and the separation prevention roller 12.

The original separated by the separation belt 11 and the separation prevention roller 12 is reversed by a first conveying roller 23 and a driven roller 24 driven by a drive motor 103.
It is inverted along 25 and conveyed toward the slit glass 2. The driven roller 24 is the paper feed case 18
Is attached to a lever 26 rotatably mounted around a fulcrum 19, and a spring 27 for pressing the lever 26 is attached.
The first transport roller 23 is pressurized by the.

A registration sensor (leading edge detecting means) 104 is provided between the original placing table 9 and the slit glass 2 on the upstream side of the slit glass 2 in the original feeding direction. Is detected and a signal is output to the ADF main controller 101. When this signal is input, the controller 101 temporarily stops driving the drive motor 103 and outputs a signal to the main body main controller 102.

This stop position constitutes a reference position (predetermined position), and when the main body main controller 102 receives a signal from the ADF main controller 101, the leading end of the transfer paper of the image forming apparatus 1 is provided in the image forming apparatus 1. It is conveyed and stopped so as to reach the registration sensor (not shown). When a refeed start signal is input from the controller 102 to the controller 101, both controllers 10
1 and 102, the drive motor 103 and the transfer sheet transport motor of the image forming apparatus 1 are driven so that the timings of the transfer sheet and the document are adjusted to transport the transfer sheet and the document.

Therefore, the first transport roller 23 and the driven roller are
In 24, the separated original is nipped and conveyed to the slit glass 2 through the reversing guide 28, and then conveyed by being picked up by the reversing discharge guide 29 to the discharge path 30, and is exposed by the exposure lamp 4, the first mirror 5, etc. The manuscript cannot be read.
A reflection guide plate 31 is provided on the slit glass 2, and the reflection guide plate 31 constitutes a white reference at the time of reading and a reflection portion of the light from the exposure lamp 4.

The speed of the document by the first transport roller 23 is higher than the speed of separating and transporting the document by the driving roller 15, so that the speed of the gear interposed between the first transport roller 23 and the drive motor 103 is increased. The gear ratio is set to be different from the gear ratio of the gear interposed between the drive roller 15 and the drive motor 103. For this reason, the space between the preceding document that is separated from the preceding document that passes through the slit glass 2 is increased.

The document conveyed to the paper discharge path 30 is nipped and conveyed by the second conveying roller 32 and the driven roller 33 driven by the driving motor 103, and then the driving motor 103.
The sheet is sandwiched between the sheet discharge roller 34 and the driven roller 35 which are driven by the sheet, is discharged to the outside from the sheet discharge path 30, is discharged by the discharging brush 36, and is then discharged onto the exterior cover 37. After this document is discharged, the following document is conveyed at a predetermined interval due to the difference in conveyance speed between the gap clutch and separation belt 11 and the first conveyance roller 12 according to the gear ratio set as described above, and the registration sensor 104 When the leading edge of the succeeding document is detected by the above, it is temporarily stopped at the reference position as described above, and waits at the reference position until the start signal is input from the main body main controller 102 to the ADF main controller 101.

On the other hand, the reflection plate 7 covering the contact glass 3 is provided on the lower surface of the pressure plate 38, and the pressure plate 38 serves to copy the original placed on the contact glass 3.
Pressure. The pressure plate 38 is rotatably attached to a main frame 40 via a fulcrum 39. The main frame 40 has an end attached to a shaft of a driven roller 35 and is fixed to the ADF 6 main body.

Further, the main frame 40 has an area for covering the contact glass 3, and an outer cover 37 is attached to the upper surface thereof, and together with the outer cover 37 constitutes a document discharge tray. The pressing plate 38 is connected to the auxiliary frame 42 via the link 41.
The auxiliary frame 42 is formed in a substantially U-shaped cross section so as to sandwich the outer peripheral portion of the main frame 40, and is rotatably connected to the main frame 40 via a fulcrum 43.

The main frame 40 also has a magnet 44.
Is provided, and this magnet 44 is
Is sucking. The auxiliary frame 42 may be entirely made of metal, or may be entirely made of an elastic member such as plastic and only the portion attracted by the magnet 44 may be made of metal. Further, a guide plate 42a forming a part of the paper discharge path 30 is formed at the front end portion (the left end portion in FIG. 1) of the auxiliary frame 42, and a driven roller 33 is rotatably provided on the guide plate 42a. Has been.

Further, a stamp unit 45 is provided on the guide plate 42a, and the stamp unit 45 causes the stamp to move in and out of the guide plate 42a by a solenoid 105 so that the original document passing through the slit glass 2 is conveyed in the direction of conveyance. The stamp is stamped at a predetermined position on the downstream side. At this time, the ADF main controller 10
Reference numeral 1 denotes an output signal from an encoder (not shown) that detects one rotation of the drive motor 103 rotation pulse from the registration sensor 104 to the stamp unit 45 when the trailing edge of the document is detected by the registration sensor 104. Based on the stamp unit
When the pulse is counted by the distance to the position of 45, the drive motor 103 is stopped to stop the document once, and the stamp unit 45 stamps the document.

By stamping this stamp, it is possible to confirm the end of reading, the double feeding failure of the document, or the facsimile transmission in the facsimile machine. Further, a handle 46 is provided on the auxiliary frame 45 portion near the guide plate 42a, and the handle 46 can be gripped by the user. Further, a stopper 47 is provided on the main frame 40, and the stopper 47 is the base end portion (the right end portion in FIG. 1) of the auxiliary frame 42.
The auxiliary frame 42 is prevented from rotating counterclockwise about the fulcrum 43 by a predetermined amount or more.
In FIG. 1, reference numeral 48 is a driven roller that is in sliding contact with the separation belt 11.

On the other hand, the ADF main controller 101 counts the rotation pulse of the drive motor 104 when the registration sensor 104 detects the trailing edge of the document, so that the trailing edge of the document passes the reading position on the slit glass 2. It is determined whether or not it has been done, and constitutes a passage detecting means together with the registration sensor 104. When the registration sensor 104 detects the leading edge of the following document, the ADF main controller 101 first detects the registration sensor 10
When it is determined that the number of rotation pulses of the drive motor 103 counted by 4 does not pass the reading position of the preceding document, the jam detection is not performed until the trailing edge of the preceding document passes the reading position. In addition, the control means is configured to drive the drive motor 104 to control the second transport roller 32 and the paper discharge roller 34 so that the rear end of the document passes from the reading position.

When the trailing edge of the preceding document passes the reading position based on the number of pulses of the drive motor 103, the ADF main controller 101 detects the subsequent document from the reference position based on the detection signal from the registration sensor 104. The amount of protrusion (feed amount) of the leading edge is counted, and when the amount of protrusion of the following document is equal to or less than a predetermined value, jam detection of the following document is not performed, and
Re-driving the first feeding roller 23 by delaying the feeding start timing of the document stopped at the reference position by the protrusion amount (that is, delaying the re-feeding start signal) and driving the drive motor 103 again. Is designed to do.

In this embodiment, the calling roller 10, the separation belt 11, the separation prevention roller 12, the driving roller 15, the driven roller 16,
The first conveyance roller 23 and the driven roller 24 constitute a separation conveyance means 51, and the second conveyance roller 32, the driven roller 33, the paper ejection roller 34 and the driven roller 35 constitute a paper ejection means. Next, FIGS.
The operation will be described based on the following.

4 to 6 show the ADF main controller 101.
C of the controller 101, which is stored in the ROM provided in
It is a program executed by the PU. First, it is determined whether or not the document is being conveyed (step S1), and when it is determined that the document is not being conveyed, the count value of the rotation pulse of the drive motor 104 is cleared (step S2).

If the sheet is being conveyed in step S1, it is determined that the following operation has been performed. That is, when the document stack P is placed on the document table 9 with the document surface facing upward and the start switch is pressed, the pressure plate 14 calls up the roller.
By pressing the document bundle P against 10, the document bundle is conveyed toward the separation belt 11 by the calling roller 10. After the uppermost original is separated from the original stack P by the separation belt 11 and the separation prevention roller 12, the first conveyance roller 23
And the driven roller 24 conveys it along the reversing path 25 onto the slit glass 2. The drive motor 10
The rotation pulses of the drive motor 103 are counted from the time point 3 is started.

Next, it is determined whether or not the original is being read (step S3), and if it is not being read, the flow shown in FIG. 5 is executed. First, it is determined whether or not the leading edge of the document is detected by the registration sensor 104 (step S2
1), the drive motor when the registration sensor 104 is turned on
The drive of 103 is stopped and the pulse count value of the drive motor 103 is cleared (step S22). For this reason,
The original document is stopped at the reference position and waits at the reference position until a refeed start signal is input.

Further, in step S21, the registration sensor is set to O.
If not, it is determined whether or not the pulse count value of the drive motor 103 has exceeded a predetermined pulse (100 pulses).
If not, it is determined that the original has not reached the registration sensor 104, the driving of the drive motor 103 is stopped, and a jam is displayed by an operation unit (not shown) (step S2).
Four).

On the other hand, when it is determined in step S3 that the document is being read, it is determined that the document is passing through the slit glass 2 and it is determined whether the registration sensor 104 is turned off (step S4) If the registration sensor 104 is not OFF, it is determined whether or not the pulse count value of the drive motor 103 is 1.5 times or more the length of the document (step S5).

When it is determined that the pulse count value is not less than 1.5 times the length of the document, it is determined that the document is jammed in the reversing path 25 and the driving of the drive motor 103 is stopped. A jam is displayed by an operation unit (not shown).
If the registration sensor 104 is turned off in step S4, it is determined whether the trailing edge of the document has passed the reading position based on the pulse count value of the drive motor 103 counted from the position of the registration sensor 104. (Step S
7) If it passes, it is determined again whether or not the registration sensor 104 is turned on (step S8).

Here, when the registration sensor 104 is ON, the succeeding original document is conveyed at a predetermined interval from the preceding original document due to the difference in conveyance speed between the gap clutch and separation belt 11 and the first conveying roller 12. At this time, it is determined that the items will be transported along. Conversely, in this embodiment, when the subsequent document is detected by the registration sensor 104, the drive motor 103 is driven to convey the document even when the trailing edge of the preceding document is passing the reading position. It continues to pass the reading position.

Next, when the preceding document passes the reading position, the number of pulses of the drive motor 103 from the time when the leading edge of the following document is detected by the registration sensor 104 is counted, and the reference position of the following document is determined. The amount of jumping out of the sheet is counted, and when it is sent out by 10 mm or more, it is determined that the jammed paper is jammed, the driving of the drive motor 103 is stopped, and the jammed display is performed by the operation unit (not shown).

If it is within 10 mm, the delay time at the time of re-feeding is set by an amount corresponding to the pop-out amount and the jam detection is not performed (step S11), and the flow of FIG. 6 is executed. In other words, if the following document is conveyed with a slight amount of conveyance and exceeds the reference position by a predetermined amount, a distance (within 10 mm) sufficient for the exceeded amount to rise to the conveyance speed corresponding to the copy magnification to the reading position. ),
The timing to start the conveyance of the following original is delayed by the amount of protrusion from the reference position, and the original is conveyed to the reading position at the same conveyance start timing as when stopped at the reference position, and conveyed at the conveyance speed according to the copy magnification. To do.

Specifically, in the case of making a reduced copy of an original, the original conveying speed is made high and the original is read by the exposure lamp 4, the first mirror 5, etc., and in the case of making an enlarged copy of the original, the original is made. The document is read by the exposure lamp 4, the first mirror 5, etc., while the conveyance speed is slowed. Therefore, if the leading edge of the original protrudes 10 mm or more from the reference position to the reading position when reducing the original, the distance from the leading edge of the original to the reading position becomes shorter, and the feeding speed corresponding to the copy magnification cannot be reached. Will end up.

Therefore, when the amount of protrusion of the leading edge of the original from the reference position is a distance (within 10 mm) sufficient to rise to the conveying speed corresponding to the copy magnification to the reading position, the timing for starting the conveyance of the succeeding original. Is delayed by the amount of protrusion from the reference position, so that the subsequent original is conveyed to the reading position at the same conveyance start timing as that apparently stopped at the reference position and is conveyed at a conveyance speed according to the copy magnification. To do so.

This flow will be described with reference to FIG. In FIG. 6, in step S31, it is determined whether or not the document delay is set, and if it is not set, the drive motor 103 is driven based on a refeed start signal from the main controller 102 of the main body. Resume document feeding (step S3
3) If it is set, it is judged whether or not the count time of the delay timer is longer than the set delay time (step S32), and if it is longer, the drive motor
103 is driven to restart document feeding (step S3
3).

Needless to say, the set value of the delay time is set to an optimum value depending on the distance from the registration sensor 104 to the reading position. As described above, in this embodiment, when it is detected that the leading edge of the following document is at the reference position, the trailing edge of the preceding document passes the reading position when the preceding document is passing the reading position. Since the original is conveyed by the second conveying roller 32, the paper ejecting roller 34, etc. without detecting the jam until the original is conveyed by the second conveying roller 32, the paper ejecting roller 34, etc., the preceding original and the following original are conveyed. When the distance between them is short, the reading of the preceding document can be reliably performed, and it is possible to prevent erroneous copying of the preceding document.

When the preceding document passes the reading position, the amount of protrusion of the leading edge of the following document from the reference position is counted based on the detection signal from the registration sensor 104,
If the amount of protrusion of the following document is 10 mm or less, jam detection of the following document is not performed, and the conveyance start timing of the document stopped at the reference position is delayed by the amount of protrusion and the first conveyance roller 23, etc. When the following document is transported with a little delay and jumps out of the reference position, the document is transported to the reading position at the same transport start timing as when it apparently stopped at the stop position. It is possible to carry at a carrying speed according to the copy magnification, and it is possible to carry out smooth carrying control without interruption of carrying due to jam detection.

[0050]

According to the first aspect of the present invention, when a document is conveyed with a little feeding, the distance between the preceding document and the following document is short, and the following document stops at a predetermined position, When the preceding document does not pass the reading position, the jam detection is not performed until the trailing edge of the preceding document passes the reading position, so that the reading of the preceding document can be reliably performed, and the preceding document can be read. It is possible to prevent the miscopying of the document.

According to the second aspect of the present invention, when the succeeding document is conveyed with a slight amount of feeding and exceeds the stop position with respect to the predetermined position, the excess amount is conveyed according to the copy magnification to the reading position. When the distance is sufficient to rise to the speed, the document transfer start timing is delayed by the amount of protrusion from the predetermined position, and the document is moved to the reading position at the same transfer start timing as when stopped at the stop position. Since the sheet is conveyed and conveyed at a conveying speed corresponding to the copy magnification, smooth conveyance control can be performed without interruption of conveyance due to jam detection.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an embodiment of an automatic document feeder according to the present invention.

FIG. 2 is a diagram showing a state in which the automatic document feeder of the embodiment is released from the image forming apparatus.

FIG. 3 is a block diagram of a drive system according to an embodiment.

FIG. 4 is a flowchart showing a transport control according to an embodiment.

FIG. 5 is a diagram showing transport control when the determination result of step S3 in the flowchart of FIG. 4 is NO.

FIG. 6 is a flow chart showing conveyance control at the time of re-feeding of an embodiment.

[Explanation of symbols]

1 Image Forming Apparatus 2 Slit Glass (Reading Position) 4 Exposure Lamp (Image Reading Means) 5 First Mirror (Image Reading Means) 6 ADF (Automatic Document Feeder) 9 Document Placement Table 51 Separation Conveying Means 52 Paper Ejecting Means 101 ADF Main controller (control means, passage detection means) 103 Drive motor 104 Registration sensor (tip detection means, passage detection means)

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location H04N 1/00 108 H04N 1/00 108M

Claims (2)

[Claims] 1. An automatic document feeder mounted on an image forming apparatus having a reading unit stopped at a reading position, wherein the original is continuously conveyed to the reading position while the original is read by the reading unit at the reading position. An apparatus, which separates and conveys a bundle of documents placed on a document table to a reading position, a discharge unit for discharging the read document, and the separation and transport unit and discharge unit A single drive motor for driving the means, and when the preceding document finishes reading, the document following the document is separated and conveyed so as to wait at a predetermined position upstream of the reading position in the document conveyance direction. And an automatic document feeder configured to drive a paper discharge unit, a leading edge detection unit that detects that the leading edge of the document is at the predetermined position, a passage detection unit that detects that the document is at the reading position, and When it is detected that the leading edge of the succeeding document is at a predetermined position based on the detection signals from the leading edge detecting means and the passage detecting means, when the preceding document is passing through the reading position, An automatic document feeder, which is provided with control means for driving the separating and feeding means and the paper discharging means without performing jam detection until the edge passes through the reading position. 2. The control means is configured to count the amount of protrusion of the leading edge of the succeeding original document from a predetermined position based on a detection signal from the leading edge detection means when the preceding original document passes through the reading position. When the amount of protrusion of the following document is less than or equal to a predetermined value, the jam detection of the following document is not performed, and the conveyance start timing of the document stopped at the predetermined position is delayed by the amount of protrusion and the separating and conveying means is operated. The automatic document feeder according to claim 1, wherein the automatic document feeder is re-driven.