JP2004120220A - Document feeder and document feeding method, and document reader and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform document feeding operation while avoiding damage on a document when the forward end of such a document as having a folded forward end is buckled between sensors. <P>SOLUTION: Document feed operation is stopped if the forward end of a document is not detected by a range sensor within a specified time T after it is detected by a separation sensor when separating operation is started by means of a separation roller. If the forward end of the document is not detected within the specified time T by the separation sensor when separating operation is started by means of the separation roller, separating operation is repeated. When the forward end of the document is not detected by the separation sensor even after the separating operation is repeated a plurality of times, feeding operation is stopped. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a document feeder, a document feed method, a document reading device, and an image forming device, and more particularly, to a document that automatically feeds a document to a reading position of the image forming device, and automatically discharges the document after reading is completed. This is suitable for application to an apparatus for carrying.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, there is an image forming apparatus having an original feeder (ADF) for automatically stopping conveyance of a document to a reading position of the image forming apparatus and automatically discharging the sheet after reading is completed.
[0003]
In this type of document feeder, a plurality of documents placed on a document tray are separated and fed one by one on a sheet-by-sheet basis, and are placed on a platen glass serving as a reading unit of an image forming apparatus. The document is conveyed by the belt and stopped. After the image reading of the original in the image forming apparatus is completed, the endless belt is driven again, and the original on the platen glass is automatically discharged to a downstream discharge tray.
[0004]
Further, there is an image forming apparatus having an ADF that performs reading in cooperation with an image reading unit while automatically transporting a document to a reading position of the image forming apparatus, and automatically discharges the paper after the end.
[0005]
In this type of ADF, a plurality of documents placed on a document tray are separated and fed one by one, and a position facing a platen glass of a reading unit of the image forming apparatus is conveyed at a constant speed. As a result, the image is read by the image forming apparatus, the conveyance is continued even after the image reading is completed, and the document is discharged to the discharge tray.
[0006]
In any of the above-described types of ADFs, a plurality of documents placed on a document tray are separated and fed one by one in a sheet-by-sheet manner, and are conveyed to a reading position. However, the separated document may be skewed due to uneven placement of the document on the document tray and uneven conveyance force of the separation unit.
[0007]
Therefore, in order to correct such skew of the document, a registration roller is disposed between the separation unit and the reading unit, and the leading edge of the document is abutted against the registration roller to form a loop at the leading edge of the document. I have. At this time, a registration sensor for detecting the leading edge of the document is provided immediately before the registration roller in order to keep the loop amount at the time of abutting constant.
[0008]
Also, in order to improve the productivity of reading a document, a separation sensor is provided immediately after the separation unit so that separation of the next document can be started immediately after the rear end of the previous document has passed through the separation unit.
[0009]
In such an ADF, a time, a conveyance distance, and the like are measured from the start of separation, and when the leading edge of the document does not reach the registration sensor for a predetermined time or a predetermined conveyance distance, the separation operation is performed again, and a plurality of separation operations are performed. However, when the leading edge of the document does not reach the registration sensor for a predetermined time or a predetermined transport distance, the ADF is determined to be “abnormal” and the operation of the ADF is stopped.
[0010]
[Problems to be solved by the invention]
However, the following problem exists in the document feeder in the above-described conventional image forming apparatus.
[0011]
That is, in the conventional ADF, as described above, if the ADF has not reached the registration sensor for a predetermined time or a predetermined distance from the start of separation, a re-separation operation is performed. For this reason, even when a document whose conveyance is not stable, such as a bent front end of the document, causes tip buckling between the separation sensor and the registration sensor, the separation operation is performed again. As a result, the document fed from the ADF is damaged.
[0012]
Therefore, an object of the present invention is to determine that the ADF is abnormal without performing the separation operation again when the document is detected by the separation sensor when the document does not reach the registration sensor for a predetermined time or a predetermined transport distance from the start of separation. To provide a document feeder and a document feed method capable of solving the above-mentioned problems by stopping the operation and suppressing damage to the document, and a document reading device and an image forming apparatus provided with the document feeder. It is in.
[0013]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides
After separating the original from the bundle of originals into sheets and transporting the original, if the leading edge of the original is not detected by the second detecting means within a predetermined time from when the first detecting means detects the original, After executing the control for stopping the conveyance and the separation operation for separating the document from the document bundle into the sheets, if the leading end of the document is not detected by the first detection unit, the conveyance of the document is stopped and the document is stopped again. If the first detecting means does not detect the leading edge of the document even after performing the separating operation and performing the separating operation a plurality of times, control is performed to stop the document conveying operation.
It is characterized by the following.
[0014]
That is, the first invention of the present invention is:
A document placing means for placing a bundle of documents,
Separating means for performing a separating operation of separating a document from a document bundle into sheets;
Conveying means for performing an original conveying operation for conveying the original,
First detection means arranged downstream of the separation means in the transport direction;
A second detection unit arranged downstream of the first detection unit in the transport direction,
When the leading edge of the document is not detected by the second detecting means within a predetermined time after the leading edge of the document is detected by the first detecting means after the separation operation by the separating means and the start of the document conveying operation by the conveying means, While being configured to stop the transport operation,
After the start of the separating operation by the separating unit, if the leading end of the document is not detected by the first detecting unit within a predetermined time, the separating operation is performed again. The document transport operation is stopped when the leading edge of the document is not detected by the detecting means.
A document feeder characterized in that:
[0015]
In the first invention, typically, the document feeder is configured to be able to input signals from at least the first detecting means and the second detecting means, and to control at least the separating means and the conveying means. A control unit configured to enable the document to be conveyed by the control unit when the leading edge of the document does not reach the second detection unit within a predetermined time after passing through the first detection unit. If it is determined that the conveyance is abnormal, the conveyance unit is stopped, and if the leading end of the document is not detected by the first detection unit within a predetermined time after the separation operation is started by the separation unit, the separation operation is performed again. After the separation operation is performed a plurality of times, if the leading end of the document is not detected by the first detection unit, the document transport operation is stopped.
[0016]
In the first invention, typically, a registration roller is disposed downstream of the second detection unit in the transport direction.
[0017]
According to a second aspect of the present invention,
After separating the original from the bundle of originals into sheets by the separating unit, the original is conveyed by the conveying unit, and the leading end of the original is detected by the first detecting unit provided on the downstream side in the conveying direction with respect to the separating unit. After that, if the document is not detected by the second detection means provided downstream of the first detection means in the conveyance direction within a predetermined time, the conveyance of the document is stopped.
This is a document conveying method characterized by the following.
[0018]
According to a third aspect of the present invention,
After a separating operation for separating the original from the bundle of originals into sheets is performed by the separating unit, within a predetermined time, the first end of the original is provided on the downstream side in the transport direction with respect to the separating unit. When the detection is not performed by the detection unit, the separation operation is performed a plurality of times, and after the separation operation is performed a plurality of times, if the leading end of the document is not detected by the first detection unit, the conveyance is stopped.
This is a document conveying method characterized by the following.
[0019]
Further, a fourth invention of the present invention
Document placement means for placing a document bundle, separation means for performing a separation operation for separating documents from the document bundle into sheets, transport means for performing a document transport operation for transporting the document, and separation means A document reading apparatus provided with document transport means having first detection means disposed downstream in the transport direction and second detection means disposed downstream in the transport direction with respect to the first detection means. hand,
When the leading edge of the document is not detected by the second detecting means within a predetermined time after the leading edge of the document is detected by the first detecting means after the separation operation by the separating means and the start of the document conveying operation by the conveying means, While being configured to stop the transport operation,
After the start of the separating operation by the separating unit, if the leading end of the document is not detected by the first detecting unit within a predetermined time, the separating operation is performed again. The document transport operation is stopped when the leading edge of the document is not detected by the detecting means.
It is characterized by the following.
[0020]
Further, a fifth invention of the present invention provides
Document placement means for placing a document bundle, separation means for performing a separation operation for separating documents from the document bundle into sheets, transport means for performing a document transport operation for transporting the document, and separation means An image forming apparatus comprising: a document conveying unit having a first detecting unit arranged downstream in a conveying direction and a second detecting unit arranged downstream in the conveying direction with respect to the first detecting unit. hand,
When the leading edge of the document is not detected by the second detecting means within a predetermined time after the leading edge of the document is detected by the first detecting means after the separation operation by the separating means and the start of the document conveying operation by the conveying means, While being configured to stop the transport operation,
After the start of the separating operation by the separating unit, if the leading end of the document is not detected by the first detecting unit within a predetermined time, the separating operation is performed again. When the leading end of the document is not detected by the detecting means, the document feeding operation is stopped.
It is characterized by the following.
[0021]
According to the present invention configured as described above, when the document does not arrive at the second detection means for a predetermined time or a predetermined transport distance from the start of the separation operation, The transport operation is stopped without performing the separation operation again, and if the document is not detected by the first detection unit, the document is detected by the first detection unit even after performing the separation operation a plurality of times. Since the conveyance operation is stopped when the document is not detected, it is possible to prevent the document from being separated and fed when the document is bent at the front.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals.
[0023]
FIG. 1 shows an image forming apparatus according to an embodiment of the present invention. In this embodiment, a description will be given of a document feeder provided in a color image forming apparatus that superimposes and transfers four color toners onto one transfer material.
[0024]
As shown in FIG. 1, in the image forming apparatus according to this embodiment, image forming sections 10a, 10b, 10c, and 10d are sequentially arranged on an upper portion of an endless belt-shaped transfer material conveying member 8a extending in the left-right direction. It is lined up. The image forming units 10a to 10d have the same configuration.
[0025]
In these image forming units 10a to 10d, image carriers 1a, 1b, 1c, 1d are provided, respectively. Also, around these image carriers 1a to 1d, primary chargers 2a, 2b, 2c, 2d, static elimination lamps 3a, 3b, 3c, 3d, developing devices 5a, 5b, 5c, 5d, cleaners 7a, 7b. , 7c, 7d, etc., are provided.
[0026]
The developing units 5a to 5d store yellow, magenta, cyan, and black toners, respectively.
[0027]
Further, transfer chargers 6a, 6b, 6c, 6d are disposed inside the endless belt of the transfer material conveying member 8a and on the opposite sides of the positions corresponding to the respective image carriers 1a to 1d.
[0028]
Optical scanning devices 4a, 4b, 4c, and 4d are provided above the image forming units 10a to 10d, respectively, corresponding to the image forming units 10a to 10d. Of the optical scanning devices 4a to 4d, the optical scanning devices 4a and 4c are arranged in a lower stage along the vertical direction, and the optical scanning devices 4b and 4d are arranged in an upper stage.
[0029]
Then, image signals corresponding to a plurality of component colors in the document are radiated to the image carriers 1a to 1d by the optical scanning devices 4a to 4d, and the image carriers 1a to 1d are respectively assigned to the image carriers 1a to 1d. An electrostatic latent image is formed.
[0030]
In the image forming section 10a, when the latent image arrives at a developing position facing the developing device 5a due to the rotation and traveling of the image carrier 1a, yellow toner is supplied from the developing device 5a, and 1a, a yellow toner image is formed.
[0031]
When the yellow toner image reaches a transfer site opposed to the transfer charger 6a, a transfer material (not shown) is supplied to this transfer site by this time, and the transfer bias is applied by the transfer charger 6a. The yellow toner image is transferred to the transfer material.
[0032]
Thereafter, when the transfer material reaches the image forming portion 10b, the transfer material reaches the transfer portion of the image forming portion 10b by the same method as described above, and a magenta toner image is formed so as to be superimposed on the already transferred yellow toner image. .
[0033]
Thereafter, similarly, in the image forming units 10c and 10d, a cyan toner image and a black toner image are sequentially formed on the transfer material, respectively. Subsequently, the transfer material on which the four color toner images are formed is separated from the transfer material transport member 8 and reaches the fixing device 9.
[0034]
Then, in the fixing device 9, the respective color toner images are dissolved and mixed to form a color image, and the color image is fixed to the transfer material and fixed, and then discharged out of the device.
[0035]
The residual toner that has not been transferred to the image carriers 1a to 1d is removed by the cleaners 7a to 7d. Further, the residual charges in the respective image carriers 1a to 1d are discharged by the discharge lamps 3a to 3d. The toners and the electric charges are cleaned by the cleaners 7a to 7d and the charge removing lamps 3a to 3d, so that the respective image carriers 1a to 1d are in a ready state in which the subsequent image forming operation can be executed.
[0036]
Next, a description will be given of a document feeder (ADF) as a document feeder provided in the image forming apparatus 101 according to this embodiment, which is configured and operates as described above. FIG. 2 shows an outline of the ADF according to this embodiment, and FIG. 3 shows a configuration of the ADF 500.
[0037]
As shown in FIG. 2, a document feeder (ADF) 500 according to this embodiment is provided in an image forming apparatus 101 that copies a specified number of documents and prints image data. The image forming apparatus 101 is configured to be able to electrically read a document 103 on a platen glass 102 on which a document to be read is placed and execute copying.
[0038]
A document tray 510 serving as a document placing unit is configured to be able to stack the document bundle 104. The reading sensor 105 is a sensor for reading the document 103 while moving rightward in FIG.
[0039]
As shown in FIG. 3, the ADF 500 is provided with a document tray 510 as a document placement unit configured to be able to place the above-described document bundle 104. A pickup roller 531 provided as a transport unit provided in the ADF 500 is rotated by a separation motor 552 in contact with an upper portion of the document bundle 104, thereby supplying the uppermost document of the document bundle 104 to a separation roller 532 serving as a separation unit. It is a roller for feeding.
[0040]
Also, the separation roller 532 transfers the documents stacked on the document tray 510 to the ADF 500 by rotating only the separation motor 552 and feeding the documents fed by the pickup roller 531, even if the document is a plurality of sheets, to the ADF 500. This is a roller for separating and conveying.
[0041]
The document detection sensor 554 is a sensor for detecting that the document bundle 104 is placed on the document tray 510.
[0042]
Further, the separation sensor 546 as a first detection unit is a sensor for detecting a document separated and conveyed by the separation roller 532. A registration sensor 543 serving as second detection means disposed downstream of the separation sensor 546 in the transport direction collides the document with a registration roller provided further downstream in the transport direction to create an appropriate loop. It is a sensor that takes the timing to perform.
[0043]
The registration roller 535 is a roller for transporting the document to a reading position on the platen after being rotated by the transport motor 544 after the leading edge of the document abuts and a loop is formed in a stopped state.
[0044]
The reversing large roller 537 is a roller that is rotated by a reversing motor (not shown) to reverse the document.
[0045]
The transport belt 536 is rotated by the transport motor 544 and is a belt for transporting a document on the platen glass 102.
[0046]
The reversing paths 541 and 550 are paths for reversing the document 103. A reversing sensor 555 for detecting the leading edge of the document in the reversing paths 541 and 550 and generating timing is provided.
[0047]
The paper discharge roller 551 is a belt for discharging the document 103 conveyed by the conveyance belt 536 to the paper discharge tray 520. The paper discharge tray 520 is a tray for stacking the originals 103 after the reading is completed.
[0048]
The separation motor 552 is a motor for rotating the separation roller 532 and the pickup roller 531. The encoders 553a and 553b are configured to be able to detect the rotation speed of the separation motor 552.
[0049]
The transport motor 544 is a motor for rotating the registration roller 535 and the transport belt 536. The encoder 545a and 545b can detect the rotation speed of the transport motor 544.
[0050]
As described above, the ADF 500 according to the embodiment is configured.
[0051]
Next, basic operations of the ADF 500 and the image forming apparatus 101 according to the embodiment configured as described above will be described.
[0052]
That is, when the original bundle 104 is placed on the original tray 510 and the copy button (not shown) is pressed, the pickup roller 531 is rotated by the separation motor 552. As a result, the uppermost document (uppermost document) of the document bundle 104 is sent to the separation roller 532.
[0053]
In the separation roller 532, both the upper roller and the lower roller are rotated clockwise by a separation motor 552. Therefore, even when a plurality of originals are sent by the pickup roller 531, only the uppermost original is separated from other originals and conveyed to the inside of the ADF 500.
[0054]
When the registration sensor 543 detects the leading end of the document 103 separated and conveyed by the separation roller 532, the separation motor 552 abuts the leading end of the document 103 against the registration roller 535 by a predetermined amount capable of forming a predetermined loop. Stop after spinning.
[0055]
Thereafter, a predetermined loop is formed, and after a predetermined time from the stop of the separation motor, the registration roller 535 and the conveyance belt 536 are rotated by the conveyance motor 544, and the document 103 is conveyed to the reading position on the platen glass 102. Stopped.
[0056]
In the image forming apparatus 101, when the document 103 is transported to the reading position, the reading sensor 105 is moved by a motor (not shown), and the document 103 is read by the reading sensor 105.
[0057]
Thereafter, as described above, the image read by the image forming apparatus 101 is formed on a transfer sheet and output.
[0058]
On the other hand, with the end of the document reading by the image forming apparatus 101, the transport belt 536 is rotated again by the transport motor 544, and the document 103 from which the image information has been read is sent to the paper discharge roller 551. The paper discharge roller 551 is rotated by a paper discharge motor (not shown), and discharges the document 103 onto the paper discharge tray 520.
[0059]
As described above, a series of document reading operations in ADF 500 are executed.
[0060]
Next, the operation of the document feeder according to one embodiment of the present invention configured as described above will be described. FIG. 4 shows a flowchart of the operation according to this embodiment.
[0061]
As shown in FIG. 4, first, when the document bundle 104 is placed on the document tray 510 and the copy button (not shown) is pressed, the separating operation is started in step ST1.
[0062]
In step ST2, in accordance with the start of the separation operation, the control unit (not shown) provided in ADF 500 resets the counter of the number of separation operations to “0”.
[0063]
Then, in step ST3, a timer for detecting a conveyance failure is also set to “0”. Immediately thereafter, the process proceeds to step ST4, and the measurement of the timer is started.
[0064]
Simultaneously with the start of the timer in step ST4, the separation motor 552 starts rotating. In step ST5, the pickup roller 531 and the separation roller 532 are rotated, and the uppermost document of the document bundle 104 starts to be conveyed into the ADF 500. When the separation motor 552 starts, the counter is incremented by "+1" in step ST6.
[0065]
After that, in steps ST7 and ST11, the control unit (not shown) of the ADF 500 waits for a predetermined time T for the detection of the leading end of the document 103 by the registration sensor 543. Then, it waits until the timer for detecting the conveyance failure exceeds a predetermined value (predetermined time T).
[0066]
During this standby, if it is earlier that the registration sensor 543 detects the leading end of the document 103, the process proceeds to step ST8, where the control unit (not shown) of the ADF 500 continues to rotate the separation motor 552, A predetermined amount of registration loop is formed.
[0067]
Thereafter, the process proceeds to step ST9, where the control unit (not shown) of the ADF 500 stops the separation motor 552. Then, proceeding to step ST10, the control unit (not shown) of the ADF 500 determines that the separating operation has been completed normally, and continues the next document transport sequence.
[0068]
On the other hand, in step ST7 and step ST11, if the timer exceeds a predetermined value (predetermined time T) before the registration sensor 543 detects the leading end of the document 103, the process proceeds to step ST12, and the control unit (not shown) of the ADF 500 As a result, the separation motor 552 is stopped.
[0069]
When the separation motor 552 is stopped in step ST12, the process proceeds to step ST13, and the control unit (not shown) of the ADF 500 performs measurement of the counter.
[0070]
If the value measured by the counter is "2", the document separating operation has failed twice, and the control unit (not shown) of the ADF 500 determines that the conveyance is abnormal, and proceeds to step ST14. After the transition, the ADF sequence is stopped.
[0071]
On the other hand, if the measured value of the counter is “1”, the process proceeds to step ST15, and the control unit (not shown) of the ADF 500 determines whether or not the separation sensor 546 detects the leading end of the document 103. I do.
[0072]
If the leading edge of the document 103 is not detected by the separation sensor 546, the control unit (not shown) of the ADF 500 determines that the sheet feeding failure or the separation failure has occurred, and proceeds to step ST3 where the separation roller At 532, the separation operation is started again.
[0073]
On the other hand, if the leading edge of the document 103 is detected by the separation sensor 546, the control unit (not shown) of the ADF 500 determines that the conveyance is abnormal, and the process proceeds to step ST16 to stop the ADF sequence.
[0074]
As described above, the normal / abnormality of the conveyance in the document conveyance device and the document reading device is determined. When the conveyance process is abnormal, the conveyance is stopped, and when the conveyance process is normal, the conveyance process is continuously performed. .
[0075]
As described above, according to this embodiment, when the separation operation is started and the leading end of the document 103 does not reach the registration sensor 543 within a predetermined time T after passing through the separation sensor 546, the conveyance process is performed. The document transport operation is stopped when it is determined to be abnormal, and the separating operation is started. If the leading edge of the document 103 does not reach within a predetermined time after passing through the separating sensor 546, the separating operation is performed again, and When the separation sensor 546 does not detect the leading edge of the document 103 even after performing the separating operation, the transport process is determined to be abnormal, and the document transport operation is stopped. For example, when a document whose conveyance is not stable causes buckling of the leading end between the separation sensor 546 and the registration sensor 543, the document is stopped without performing the separation operation again. It is possible to it is possible to prevent damage to the original 103.
[0076]
As described above, one embodiment of the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and various modifications based on the technical idea of the present invention are possible.
[0077]
For example, in the above-described embodiment, a full-color copying machine is described as an example of the configuration of the image forming apparatus. The present invention can be applied to any image forming apparatus having the device.
[0078]
Also, for example, in the above-described embodiment, the description has been given of the document exchange type ADF in which the document 103 is stopped on the platen glass 102 and the image is read. It is also possible to use a so-called drift reading type ADF for reading while reading.
[0079]
Further, for example, in the above-described embodiment, the timer is used to detect the abnormality of the separation process. However, the separation / transport distance, which can be obtained by measuring the rotation amount of the separation motor 552, is used for detecting the abnormality. It is also possible to use.
[0080]
Further, for example, in the above-described embodiment, the document conveying device and the document reading device provided in the image forming apparatus have been described as an example. However, a device including only the image reading device and the ADF may be used. It is also possible to adopt a device configuration in which no forming unit is provided.
[0081]
【The invention's effect】
As described above, according to the present invention, after the start of the separating operation and the original feeding operation, the leading end of the original is detected by the second detecting unit within a predetermined time after being detected by the first detecting unit. When the separation operation is not performed, the conveyance operation is stopped, and after the separation operation is started, if the leading edge of the document is not detected by the first detection unit within a predetermined time, the separation operation is performed again. Even when the separation operation is performed a plurality of times, if the first detecting unit does not detect the leading edge of the document, the transport operation is stopped. When an unstable document buckles at the tip between the separation sensor and the registration sensor, it stops without performing the separation operation again, so that the transport operation is performed while avoiding damage to the document. It can become.
[Brief description of the drawings]
FIG. 1 is a sectional view showing an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic diagram illustrating a document feeder according to an embodiment of the present invention.
FIG. 3 is a schematic diagram illustrating a document feeder according to an embodiment of the present invention.
FIG. 4 is a flowchart for determining whether or not the transport is normal according to an embodiment of the present invention.
[Explanation of symbols]
1a, 1b, 1c, 1d Image carrier
2a, 2b, 2c, 2d Primary charger
3a, 3b, 3c, 3d Static elimination lamp
4a, 4b, 4c, 4d Optical scanning device
5a, 5b, 5c, 5d developing unit
6a, 6b, 6c, 6d Transfer charger
7a, 7b, 7c, 7d cleaner
8,8a Transfer material transport member
9 Fixing device
10a, 10b, 10c, 10d Image forming unit
101 Image forming apparatus
102 Platen glass
103 manuscript
104 Document Bundle
105 reading sensor
500 ADF
510 Document tray
520 paper output tray
531 Pickup roller
532 separation roller
535 registration roller
536 Conveyor belt
537 reversing large roller
541,550 Reverse path
543 registration sensor
544 Transport motor
545a, 545b, 553a, 553b Encoder
546 Separation sensor
551 discharge roller
552 separation motor
554 Document detection sensor
555 reversing sensor

Claims (7)

A document placing means for placing a bundle of documents,
Separating means for performing a separating operation of separating a document from the document bundle into sheets.
Conveying means for executing a document conveying operation for conveying the document,
First detection means arranged downstream of the separation means in the transport direction;
A second detection unit disposed downstream of the first detection unit in the transport direction,
After the separation operation by the separation unit and the document conveyance operation by the conveyance unit are started, the second detection unit is set within a predetermined time after the leading end of the document is detected by the first detection unit. The document transport operation is stopped when not detected by the
After the start of the separation operation by the separation unit, if the leading end of the document is not detected by the first detection unit within a predetermined time, the separation operation is performed again, and the separation operation is performed a plurality of times. A document feeder configured to stop the document feed operation when the first detecting means does not detect the leading end of the document. At least a signal from the first detection unit and the second detection unit is configured to be inputtable, and at least a control unit configured to control the separation unit and the transport unit is provided,
When the leading edge of the document does not reach the second detecting means within a predetermined time after passing through the first detecting means, the control unit determines that the transport of the document is abnormal. And the transporting means is stopped,
After the start of the separation operation by the separation unit, if the leading end of the document is not detected by the first detection unit within a predetermined time, the separation operation is performed again, and the separation operation is performed a plurality of times. 2. The document feeding device according to claim 1, wherein the document feeding operation is stopped when the leading end of the document is not detected by the first detecting means. 2. The document feeder according to claim 1, wherein a registration roller is disposed downstream of the second detection unit in the feed direction. After separating the original from the bundle of originals into sheets by the separating unit, the original is conveyed by the conveying unit, and the leading end of the original is provided on the downstream side in the conveying direction with respect to the separating unit. If the document is not detected by the second detection means provided downstream of the first detection means in the conveyance direction within a predetermined time after the detection, the conveyance of the document is stopped. A document conveying method characterized by the above-mentioned. After a separating operation for separating the original from the bundle of originals into sheets by the separating unit is performed, within a predetermined time, the leading end of the original is provided on the downstream side in the transport direction with respect to the separating unit. If the first detecting means does not detect the leading edge of the document, the transport is stopped if the first detecting means does not detect the leading edge of the document. A document conveying method characterized in that the document is conveyed. Document placing means for placing a document bundle, separating means for performing a separating operation for separating the document from the document bundle into sheets, transport means for performing a document transporting operation for transporting the document, and the separating means A document provided with document transport means having first detection means disposed downstream in the transport direction with respect to the first detection means, and second detection means disposed downstream in the transport direction with respect to the first detection means A reading device,
After the separation operation by the separation unit and the document conveyance operation by the conveyance unit are started, the second detection unit is set within a predetermined time after the leading end of the document is detected by the first detection unit. The document transport operation is stopped when not detected by the
After the start of the separating operation by the separating unit, if the leading end of the document is not detected by the first detecting unit within a predetermined time, the separating operation is performed again, and the separating operation is performed a plurality of times. A document reading device configured to stop the document conveying operation when the leading edge of the document is not detected by the first detection unit. Document placing means for placing a document bundle, separating means for performing a separating operation for separating the document from the document bundle into sheets, transport means for performing a document transporting operation for transporting the document, and the separating means An image provided with a document conveying means having a first detecting means arranged downstream in the conveying direction with respect to the first detecting means, and a second detecting means arranged downstream in the conveying direction with respect to the first detecting means. A forming device,
After the separation operation by the separation unit and the document conveyance operation by the conveyance unit are started, the second detection unit is set within a predetermined time after the leading end of the document is detected by the first detection unit. The document transport operation is stopped when not detected by the
After the start of the separation operation by the separation unit, if the leading end of the document is not detected by the first detection unit within a predetermined time, the separation operation is performed again, and the separation operation is performed a plurality of times. An image forming apparatus configured to stop the document conveying operation when the leading edge of the document is not detected by the first detection unit.

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