JP2002220125A - Image inputting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image inputting device capable of increasing recognition accuracy of a document length concerning a feed direction and detecting various document sizes automatically without causing erroneous detection by suppressing unevenness of document conveyance speed by a register roll. SOLUTION: This image inputting device is provided with a platen in which a document to be scanned is fed, a scanning member scanning a document image through the platen, a document tray on which a bundle of documents is set, a paper feeding roll separating and feeding a plurality of documents set on the document tray one by one, and a pair of register rolls receiving the document from the paper feeding roll and feeding it into the platen. The drive of the paper feeding roll is continued even after a tip of the document is nipped between the register rolls, the drive of the paper feeding roll is stopped until a rear end of the document passes through the paper feeding roll at the latest, and after that, the paper feeding roll is rotated by following the document conveyed by the register rolls.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input apparatus for separating and feeding a plurality of originals one by one in a copying machine, a facsimile or the like, and scanning an image of the originals. The present invention relates to an improvement in an image input device capable of detecting the size of a document when feeding the document to a platen.

[0002]

2. Description of the Related Art In a copying machine or a facsimile, an image input device for separating a plurality of originals one by one and taking in the original image is indispensable for its function of copying or transmitting the original. An image input device of this type includes a platen into which a document to be scanned is fed, a scanning member for scanning a document image through the platen, a document tray on which a bundle of documents is set, and one document from the document tray. A pair of registration rolls (hereinafter, referred to as “registration rolls”) for feeding the originals sequentially fed from the paper supply rolls to a platen such as a copying machine; 2. Description of the Related Art A platen belt is generally known that includes a platen belt that is conveyed on a platen, and a discharge tray that discharges documents that have passed through the platen.

As a method of scanning a document sent to a platen, a so-called optical system moving system in which a document is temporarily stopped on the platen and scanning is performed while the scanning member is moved under the platen. On the contrary, there is known a so-called sheet moving system in which the scanning member is stopped under the platen, and an image of the original is captured while the document is being conveyed on the platen.

In any of the scanning methods, a plurality of documents stacked on a document tray are separated one by one by a paper feed roll and sent to a platen. The registration roll provided in between temporarily stops its rotation when the trailing edge of the document passes through the registration roll, and starts rotating again after a lapse of a predetermined time from the start timing of feeding the previous document to the platen. It is configured.

[0005] In addition to synchronizing the feeding interval of the original to the platen with the image forming operation of the copier, the skew of the original generated during the feeding by the paper feed roll (oblique feeding in the transport direction) is brought before the platen. It is necessary to remove it on the side. That is, when the trailing edge of the previous document exits the registration roll, the registration roll stops its rotation, so that when the next document is fed from the document tray by the feed roll, the leading end of the document is nipped by a pair of registration rolls. It is locked against the part. When the paper feed roll further feeds the document in this state, the document is bent in the transport path,
The skew of the document is absorbed by this bending. Then, when the rotation of the registration roll is resumed after that, the document is sandwiched between the registration rolls and sent to the platen in a state where the skew generated on the front side of the registration roll is removed.

On the other hand, the paper feed roll is stopped when the document locked by the registration roll slightly bends (loops), and even if the registration roll is restarted, the paper feed roll remains until the start of feeding the second document. It merely rotates following the conveyance of the first document. This is because, when the trailing edge of the document passing through the registration roll passes through the paper feed roll, if the paper feed roll is activated, the second document is sent following the first document. This is because a fixed interval synchronized with the image forming operation of the copying machine cannot be created between the two originals that are scanned back and forth.

In a copying machine or a facsimile,
In order to automatically select the size of a recording sheet on which a document image is to be output, it is necessary for the image input device to accurately grasp the document size. When scanning an original image by the optical system moving method, it is possible to detect the original size when the original is set at a predetermined position on the platen, but in the case of the sheet moving method, the original size is detected on the platen. Cannot be detected. For example, the size of the document is detected by counting the time during which the document crosses the front surface of a sheet detection sensor (hereinafter, referred to as “registration sensor”) provided immediately before the registration roll. I have. That is, after counting the time during which the main signal of the registration sensor is ON, the count value is applied to a pre-stored size table in the document feeding direction, thereby specifying the corresponding document size. If you can grasp the length of the document in the width direction orthogonal to the feed direction,
The document size is determined. However, in the width direction,
There is a guide plate on the document tray for regulating the position of the document in the width direction. By checking the position of the guide plate with a sensor, the length of the document can be easily grasped. Therefore, the document size can be ascertained by checking only the output signal of the registration sensor.

[0008]

However, in consideration of variations in the length of the document itself, curl or folding of the document, etc.,
The document length stored in the size table in the feed direction needs a tolerance of about ± 2 to 3 mm. In addition, since there is a variation in the document conveying speed, a tolerance of about ± 5 to 6 mm is required for the variation, and a total tolerance of about ± 10 mm must be anticipated in consideration of a margin for detection accuracy. . As described above, the cause of the variation in the document conveyance speed is largely due to the drive control of the paper feed roll. That is, when the leading edge of the document is already sandwiched between the registration rollers, the paper feed roll does not rotate by itself but rotates following the document being transported. A large frictional force, in other words, a load acts between them. This frictional force is easily affected by the paper quality of the manuscript and the temperature and humidity of the day,
Since the load also changes due to the deterioration of the paper feed roll over time, the load is not constant but changes for each copy job or facsimile transmission job. For this reason,
Even if the register roll is rotated at a constant torque, the conveyance speed of the original document varies.

Therefore, if the count value obtained from the registration sensor falls within the range of the tolerance, it is not possible to distinguish the difference in the length of the document in the feed direction, and the count value falls within the range of the tolerance. As for two original sizes whose original lengths are close to each other, these cannot be automatically identified. Therefore, when using an inch series, computer form paper, or the like as a document in addition to the standard sizes of the A series and the B series, it is necessary for the user to manually input the document size.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to improve the accuracy of document length recognition in the feed direction by suppressing variations in document transport speed due to registration rollers. Accordingly, it is an object of the present invention to provide an image input apparatus capable of automatically detecting various document sizes without erroneous detection.

[0011]

In order to achieve the above object, an image input apparatus according to the present invention comprises a platen to which a document to be scanned is fed, a scanning member for scanning a document image through the platen, and a document bundle. , A paper feed roll that separates and feeds a plurality of documents set in the document tray one by one, and a pair of papers that receive the documents from the paper feed rolls and send them to the platen. The paper feed roll continues to be driven even after the leading end of the document is sandwiched between the register rolls, and at the latest, the paper feed is performed until the trailing edge of the document passes through the paper feed roll. The driving of the roll is stopped, and thereafter, the paper feed roll is driven to rotate with respect to the document conveyed by the registration roll.

According to such a technical means, even after the leading end of the document separated and fed by the paper feed roll reaches the registration roll and the document can be conveyed by the registration roll thereafter, the above-described operation is performed. Since the paper feed roll is continuously driven to assist the document conveyance, the paper feed roll does not become a load for the conveyance of the document, and the variation in the document conveyance speed is suppressed. In addition, the driving of such a paper feed roll is stopped before the trailing end of the document has passed through the paper feed roll, and thereafter, the document conveyed by the registration roll causes the paper feed roll to rotate. When the trailing end of the document being conveyed passes through the paper feed roll, the rotation of the paper feed roll is stopped, and the second document is not sent without leaving an interval from the first document.

By driving the paper feed roll in this manner, the tolerance of the document size table set in consideration of the variation in the document transport speed can be reduced, so that different types of paper having different lengths in the feeding direction can be used. Documents of different sizes can be distinguished from each other, and the trouble of manual input of the document size by the user can be reduced.

Here, from the viewpoint that the feeding roll does not exert a load on the conveyance of the document after the document is sandwiched between the registration rolls, the speed at which the document is conveyed by the registration roll can be reduced. It is preferable that the transport speed is equal to or higher than the transport speed. By setting the document feed speed by the paper feed roll in this way, no tension acts on the document between the registration roll and the paper feed roll, and the paper feed roll applies a load to the document being conveyed by the registration roll. Not even.

On the other hand, in the present invention, it is necessary to stop the paper feed roll before the trailing end of the document passes through the paper feed roll, and it is important to determine the timing of the stop. This stop timing may be determined unambiguously, for example, in accordance with the minimum size original that can be automatically fed, or may be determined based on the original size estimated from the width of the original in the width direction. The determination may be made in accordance with the minimum size document. In the former case, regardless of the size of the document, the paper feed roll rotates and stops for a certain period of time after the leading edge of the document is sandwiched between the registration rolls. Even when the drive stop timing of the paper feed roll is determined in this way, the load acting on the document from the paper feed roll is reduced, and it is possible to suppress variations in the document transport speed. Further, in the latter case, it is possible to further delay the drive stop timing of the paper feed roll according to the size of the original, so that the load acting on the original is further reduced as compared with the former case, and It is possible to effectively suppress variations in the document conveyance speed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an image input device according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an example of a digital color copier equipped with the image input device of the present invention. This copier optically reads image information of a document 11 placed on a platen glass 10 and
An image input unit 1 converts the image data into electrical image data by the CD sensor 12, and an image output unit 2 forms an image on a recording sheet P based on the image data transferred from the image input unit 1. Further, the image input unit 1 includes an automatic document feeder (ADF) 13 for automatically feeding the document 11 to the platen glass 10.

The image output unit 2 forms a toner image on the photosensitive drum 20 based on the image data transferred from the image input unit 1, and then primarily transfers the toner image to an endless transfer belt 3. Further, a recording image is formed on the recording sheet P by secondary-transferring the toner image on the transfer belt 3 onto the recording sheet P. The recording sheet P on which the toner image has been secondary-transferred passes through the fixing device 4. The paper is discharged onto the discharge tray 50.

The photosensitive drum 20 is rotated in a direction indicated by an arrow at a predetermined process speed, and around the photosensitive drum 20, the surface of the photosensitive drum 20 is uniformly charged to a predetermined background potential. A charging corotron 21, a laser beam scanner 22 that exposes the photosensitive drum 20 with a laser beam modulated based on image data and forms an electrostatic latent image on the photosensitive drum 20, and black, yellow, magenta, and cyan And a rotary developing unit 23 for developing an electrostatic latent image on the photosensitive drum by any one of the developing units, and a developing unit 23 on the photosensitive drum 20 prior to the primary transfer of the toner image to the transfer belt 3. A pre-transfer treatment corotron 24 for removing potential and a cleaner 25 for removing residual toner on the photosensitive drum 20 after the primary transfer of the toner image is disposed. That.

On the other hand, the transfer belt 3 is wound around a plurality of rolls and rotates in the direction of the arrow,
The toner images of each color sequentially formed on the transfer belt 3
After the multiple transfer to the recording sheet P, the secondary transfer is collectively performed from the transfer belt 3 to the recording sheet P. At a position facing the photosensitive drum 20 with the transfer belt 3 interposed therebetween, a primary transfer roll 30 for forming a transfer electric field between the photosensitive drum 20 and the primary transfer roll 30 is provided. Is the secondary transfer roll 31 and the counter electrode roll 3
The recording sheet P is inserted between the secondary transfer roll 31 and the transfer belt 3 to receive the transfer of the toner image. A belt cleaner 33 that removes paper dust and residual toner from the surface of the transfer belt 3 after the secondary transfer is provided between the secondary transfer position and the primary transfer position in the rotation path of the transfer belt 3. Is provided.

Below the image output section 2, four-stage sheet feeding cassettes 5a to 5d containing recording sheets P of different sizes are provided, and the size of the original detected by the image input section 1 is reduced. Recording sheet P of appropriate size according to
Are fed from one of the sheet feeding cassettes to the image output unit 2 by the rotation of the feed roller 51. A plurality of sheet transport rolls 52 are provided on the transport path of the recording sheet P from each of the sheet feeding cassettes 5a to 5d to the secondary transfer position of the toner image, and registration is performed immediately before the secondary transfer position. A roll 53 is provided, and the registration roll 53 transfers the recording sheet P sent from the sheet feeding cassettes 5a to 5d at a predetermined timing synchronized with a timing of writing an electrostatic latent image on the photosensitive drum 20. Send to the next transfer position.

In FIG. 1, reference numeral 26 denotes an image processing which supplies the laser beam scanner 22 after processing the image data transferred from the image input unit 1 to the image output unit 2 in accordance with the contents of the copying operation. , Reference numeral 54 denotes a manual feed tray used for manual feeding of the recording sheet P, reference numeral 55 denotes a sheet conveying belt for feeding the recording sheet P on which the toner image has been secondarily transferred to the fixing device 4, and reference numeral 56 denotes a recording sheet. P
This is an inverter path for inverting the recording sheet P and feeding it from the fixing device 4 to the secondary transfer position at the time of double-sided copying.

In the color copying machine of the present embodiment having the above-described configuration, the laser beam scanner 22 exposes the photosensitive drum 20 based on the image information of the original taken in by the image input unit 1, and the photosensitive drum 20 is exposed first. An electrostatic latent image corresponding to black is written on the body drum 20. on the other hand,
In the rotary developing unit 23, a developing device for black toner is set at a position facing the photosensitive drum 20, and the electrostatic latent image is developed by the black developing device with a slight delay from its writing timing. Then, the black toner image thus formed is transferred to the primary transfer roll 3.
0, the image is primarily transferred onto the transfer belt 3, and the transfer belt 3 rotates while carrying the toner image. When the developing process by the black developing device is completed, the transfer belt 3
The developing device is replaced before the rotation cycle is completed, and the developing device for yellow toner is set at a position facing the photosensitive drum 20 by rotating the rotary developing unit 23 by 90 °.

Thereafter, these operations are repeated for each rotation cycle of the transfer belt 8, and each time, the yellow, magenta and cyan toner images are transferred from the photosensitive drum 20 to the transfer belt 3. , A superimposed toner image of four color toner images is formed. The full-color multi-transferred toner image thus formed is secondarily transferred to the recording sheet P sent from the registration roll 53 at a predetermined timing, and the unfixed toner image is transferred to the recording sheet P. The sheet is discharged to the discharge tray 50 via the fixing device 4.

Next, the configuration of the image input unit will be described. As described above, the image input unit 1 causes the reflected light of the document 11 set on the platen glass 10 to be incident on the solid-state imaging device such as the CCD sensor 12, thereby converting the image information of the document 11 into an electric signal. Is configured. Below the platen glass 10, the platen glass 1
A lamp for illuminating the original 11 through the reference numeral 0, a plurality of reflection mirrors and lenses for guiding reflected light of the original obtained as a result of the illumination to the CCD sensor 12 and forming an image are provided. Illumination lamp and some mirrors are platen glass 1
The carriage 11 is mounted on a carriage that can move along the axis 0, and the carriage moves so that the original 11 that is stationary on the platen glass 10 can be scanned. In addition, this carriage can be stopped at a predetermined position below the platen glass 10, and the original 11 can be moved on the platen glass 10 by using the above-mentioned ADF so that the original 11 can be scanned by a so-called sheet-through method. Is configured.

FIG. 2 shows the configuration of the ADF 13 provided on the platen glass 10. The ADF 13 is provided so as to cover the platen glass.
When the copying operation is performed without using the F, the original can be opened and closed to manually replace the original on the platen glass.

In FIG. 2, reference numeral 60 denotes an original tray on which a bundle of a plurality of originals is set, and reference numeral 61 denotes an original tray 6.
A pick-up roll 62 abuts on the original 11 stacked on the top 0 and draws the original 11 into the paper feed path R1 inside the ADF 13. Reference numeral 62 denotes a separation of the original 11 drawn by the pickup roll 61 into individual sheets. Reference numeral 63 denotes a feed roll for feeding, and reference numeral 63 denotes a retard roll which is disposed opposite to the feed roll 62 to prevent double feeding of the document 11, and reference numeral 64 denotes a document which is temporarily fed from the document tray 60. A registration roll that locks and feeds the original 11 on the platen glass 10 at a predetermined timing. Reference numeral 65 denotes a platen belt that conveys the original 11 on the platen glass 10. Reference numeral 66 denotes a platen belt 65 that is removed from the platen glass 10 by the platen belt 65. An exit roll for sending the document 11 onto the document discharge tray 67.

Here, the feed roll 62 and the pickup roll 61 are a first motor (not shown), the registration roll 64 and the platen belt 65 are a second motor (not shown), and the outlet roll 66 is a third motor. (Not shown).
Is connected to a second motor via a clutch (not shown) so that the motor can be stopped even while the platen belt 65 is rotating. Further, the paper feed roll 62 and the pickup roll 61 are connected to a first motor via a one-way clutch (not shown) so that the paper feed roll 62 and the pickup roll 61 can rotate following the conveyance of the original by the registration roll 64.

A registration sensor 71 for detecting whether or not the document 11 has reached the registration roll 64 is provided immediately before the registration roll 64.
An exit sensor 72 for detecting whether or not the sheet has been discharged to the document discharge tray 67 is provided. Each of the rolls and the platen belt 65 described above are driven at a predetermined timing synchronized with the detection signals of these sensors. Has become.

The ADF 13 also has an automatic reversing mechanism for the original 11 corresponding to double-sided copying. The original 11 drawn on the platen glass 10 is sent again to the paper feed path R1 via the inversion path R2. , Manuscript 11
Is inverted and can be sent onto the platen glass 10. A transport roll 68 is provided in the reversing path R2, and the original 11 is
An inverter sensor 69 for confirming that the vehicle has passed through the inside 2 is provided.

Further, a document detection sensor 70 is provided at the entrance of the paper feed path R1. When the document detection sensor 70 detects a document set on the document tray 60, it is provided immediately after the pickup roll 61. The supplied paper gate (not shown) protrudes into the paper supply path, and regulates the setting position of the document 11 on the document tray 60.

In FIG. 2, reference numeral 75 denotes the original 11
A gate plate for smoothly sending the original 11 drawn on the platen glass 10 to the reversing route R2 while smoothly feeding the original 11 from the transport path R1 onto the platen glass 10, and a lamp 76 and a mirror 76 for illuminating the original 11 Is a carriage on which is mounted.

FIG. 3 is a plan view of the document 11 set on the document tray 60 when viewed from above. On the document tray 60, a pair of guide plates 73 that can move along the width direction of the document 11 (the direction of the arrow A) is provided upright.
The guide plate 73 guides the document 11 so that skew generated when the document 11 is pulled in can be minimized. The position of the guide plate 11 is grasped by a position sensor (not shown), and by adjusting the standing position of the guide plate 11 in accordance with the size of the document 11, the position of the document 1 is reduced.
1 can be ascertained in the width direction.

When the ADF 13 is used, the image input section 1 of the present embodiment configured as described above reads an original image as follows. First, when the copy start button of the copier body is pressed, the document detection sensor 70 checks the presence or absence of the document 11 on the document tray 60, and
If it is determined that the document 11 is present in the document tray 60, the pickup roller 61 and the sheet supply roller 62 are driven to rotate, and the document 11 is drawn into the sheet supply path R1. Since the pickup roll 61 is in contact with the original bundle only from above, when the pickup roll 61 rotates,
Not only the top document 11 but also the second document advances toward the paper feed roll 62, but the non-rotatable retard roll 63 contacts the paper feed roll 62 from below, so the two The advance of the eye original is stopped by the frictional force of the retard roll 63, and only the uppermost original 11 is separated from other originals and advances in the transport path R1.

At this point, the registration roll 64 is still stopped, and when the leading end of the document 11 fed into the transport path R 1 by the paper feed roll 62 reaches the registration roll 64, it is locked by the registration roll 64. Also,
The rotation of the paper feed roll 62 and the pickup roll 61 by the first motor is stopped a predetermined time after the registration sensor 71 detects the leading end of the document 11, and the leading end is moved to the registration roll 64.
The document 11 locked by the above is held in a slightly bent state in the transport path R1. And cashier roll 6
Reference numeral 4 temporarily starts the rotation after temporarily locking the leading end of the document 111, and feeds the document 11 to the platen glass 10. As a result, the leading end of the document 11 is sandwiched between the pair of registration rolls while being aligned in parallel with the axial direction of the registration roll 64,
The skew of the document 11 that has occurred before reaching the registration roll 64 is eliminated.

The platen belt 65 rotates together with the registration roll 64, and conveys the document 11 on the platen glass 10. When reading a document image by a so-called document fixing method in which the carriage 76 is moved to scan the document 11, the platen belt 65 stops with the document 11 set at a predetermined position on the platen glass 10. Thereby, the original 11 can be scanned by moving the carriage 76. Then, when the scanning of the document is completed, the platen belt starts rotating again, and the document is discharged to the document discharge tray via the exit roll.

On the other hand, when reading a document image by a so-called sheet-through method in which the document 11 is scanned while moving the document 11 on the platen glass 10, the platen belt 65, which has received the document 11 from the registration roll 64, rotates. The carriage 76 where the document 11 is stopped at a predetermined position.
At a predetermined speed. As a result, scanning of the document 11 is performed with the carriage 76 stopped. Then, the document is delivered as it is to the exit roll and discharged to the document discharge tray.

In any of the scanning methods, when a predetermined time has elapsed since the trailing end of the document 11 is detected by the registration sensor 71, the registration roll 64 is moved by the clutch to the second position.
The motor is separated from the motor, and the registration roll 64 stops rotating. As a result, the leading end of the next original 11 is
Preparations are made for locking.

In the image input apparatus of this embodiment which is constructed and operates as described above, the size of the document 11 in the conveying direction is detected by using the registration sensor 71, and is detected from the detection result and the standing position of the guide plate 73. The size of the original fed to the platen glass 10 is recognized from the relationship with the size of the original 11 in the width direction. That is, manuscript 1
After the registration roll 64, which has locked the leading end of the document 11, starts rotating and sandwiches the leading end of the document 11,
Is counted until the rear end of the document 11 passes the position facing the registration sensor 71, and this count value is compared with a previously stored document size table, and the length of the document 11 in the transport direction is determined from the comparison result. are doing. When the size of the document 11 in the conveyance direction is determined, the size of the document is determined from the relationship with the size of the document in the width direction. By transmitting the document size information to the image output unit 2, an appropriate sheet feeding cassette is always provided. It is possible to select and perform a copy operation.

The value stored in the document size table must include a tolerance in consideration of variations in the length of the document 11 itself, bending, bending, and the like. Is included in the range of the tolerance, it is determined that the document 11 corresponds to the size. However, in the conventional image input apparatus, since the conveyance speed of the document 11 by the registration roll 64 varies greatly, the tolerance needs to be about ± 10 mm with respect to the actual length of the document 11 in the conveyance direction. Even if two types of documents are slightly different from each other, if the actual count value of the registration sensor 71 is included within the same tolerance, the document may be erroneously determined to be the same length document. there were.

As described above, the original 11 by the registration roll 64
The cause of the variation in the transport speed of the paper feed roller is the driven rotation of the paper feed roll 62 and the pickup roll 61. That is, in starting the feeding of the document 11 by the registration roll 64, the sheet feeding roll 62 and the pickup roll 61 are not driven by the first motor. Only the driven rotation. FIG. 4 shows the feed roll 62 and the registration roll 6 at that time.
4 is a timing chart illustrating a driving state of No. 4 and a detection signal of a registration sensor 71. As shown in this timing chart, when the drawing of the first document 11 is started by the drive start (ON) of the paper feed roll 62, the signal of the registration sensor 71 is turned ON for a while, and the signal of the registration sensor 71 is turned ON. Immediately after being turned on, the document 11 reaches the registration roll 64. The document feed roller 62 continues to rotate for a while after the document 11 arrives at the registration roll 64, whereby the document 11 locked on the registration roll 64 is bent for skew correction. A short while after the paper feed roll 62 stops, the feeding of the original 11 by the registration roll 64 is started (ON). At this time, the paper feed roll 62 is not driven, and only the driven rotation relative to the original 11 is performed. It is. Therefore, manuscript 1
Reference numeral 1 denotes a state in which the document 11 is conveyed while being dragged by the paper feed roll 62 and the pickup roll 61, and a load corresponding to the frictional force with the paper feed roll 62 and the like acts on the feeding of the document 11 by the registration roll 64. Become. This allows
Conventionally, the document feeding speed by the registration roll 64 tends to vary.

On the other hand, in this embodiment, the registration roll 64 is used.
The paper feed roll 62 and the pick-up roll 61 are driven again in response to the start of feeding of the document 11. FIG. 5 is a timing chart at that time. As is apparent from FIG.
At about the same time as the feeding of the document 11 is started, the paper feed roll 62 and the pickup roll 61 start driving and rotating, and feed the document 11 together with the registration roll 64. As a result, the load acting on the feeding of the document 11 by the registration roll 64 is reduced, and variations in the document transport speed can be suppressed. For this reason, the tolerance included in the document size table can be set smaller than before, and it is possible to recognize two types of documents whose lengths in the conveying direction are close to each other as documents of different sizes.

On the other hand, at the stop timing of the sheet supply roll 62 and the pickup roll 61 whose driving has been resumed together with the registration roll 64, at least the rear end of the document 11 must
The drive must be stopped by the time the document 1 is completely removed, and thereafter driven by the conveyance of the document. However, the length of the first document 11 in the transport direction cannot be determined until the rear end of the document has passed the position facing the registration sensor 71, and the pickup roll 6 is determined based on the prediction.
It is necessary to determine the drive stop timing of No. 1.

In the image input section 1 of this embodiment, the document tray 6
By guiding the side edge portion of the original 11 on the guide plate 73 with the guide plate 73, the size of the original 11 in the width direction can be grasped. Therefore, the size of the original 11 in the width direction is specifically grasped. Then, the minimum size of the length in the transport direction can be grasped. If the drive stop timing of the pickup roll 61 and the paper feed roll 62 is determined according to the minimum size document derived from the size of the document 11 in the width direction, the first motor is always driven until the rear end of the document 11 is completely removed. The connected pickup roll 61 and the like can be stopped. The drive stop timing of the pickup roll 61 and the paper feed roll 62 varies depending on the size of the document set on the document tray 60.

Further, without using the size information in the width direction of the original 11, the pickup roll 61 is adjusted to the minimum original size that can be automatically fed using the ADF 13.
It is also possible to determine the drive stop timing of the paper feed roll 62. In this case, the paper feed roll 62 and the pickup roll 61 are connected to the first motor at the same time as the driving of the registration roll 64, and are always separated from the first motor after a certain time, and thereafter follow the original 11. .

By determining the drive stop timing of the feed roll 62 and the pickup roll 61 as described above, it is possible to rotate the feed roll 62 together with the registration roll 64 while preventing double feeding of the original 11. . However, for the second and subsequent documents, the length of the document in the transport direction can be ascertained when the trailing edge of the first document has passed the registration sensor 71. Under the condition that the document is set on the tray 60, it is possible to determine the drive stop timing of the paper feed roll 62 and the pickup roll 61 by using the already-determined first document size.

In the image input section of the present embodiment configured as described above, the paper feed roll 62 is driven together with the registration roll 64 even for a short time after the conveyance of the document 11 by the registration roll 64 is started. Accordingly, it is possible to suppress the paper feed roll 62 from being a load of document conveyance by the registration roll 64, thereby suppressing variations in document conveyance speed by the registration roll 64. As a result, variation in the time required for the rear end of the document 11 to cross the front surface of the registration sensor 71 is suppressed, so that the accuracy of detecting the length of the document 11 in the transport direction can be improved, and the approach of the transport direction length can be improved. This makes it possible to automatically distinguish between the two types of originals, for example, the size of an inch-series original and the size of an A-series or B-series original.

[0047]

As described above, according to the image input apparatus of the present invention, since the variation of the document transport speed is suppressed, the document size table set in consideration of the variation of the document transport speed by the registration roll. , It is possible to discriminate between different size originals having similar lengths in the feed direction,
It is possible to increase the accuracy of recognizing the document length in the feed direction and automatically detect various document sizes without erroneous detection.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an embodiment of a digital color copier including an image input unit.

FIG. 2 is a schematic diagram illustrating a configuration of an image input unit to which the present invention has been applied.

FIG. 3 is a plan view of an image input unit according to the embodiment.

FIG. 4 is a timing chart showing a driving timing of a paper feed roll in a conventional image input unit.

FIG. 5 is a timing chart illustrating a driving timing of a paper feed roll in the image input unit according to the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image input part, 2 ... Image output part, 10 ... Platen glass, 11 ... Original, 13 ... ADF, 60 ... Original tray, 6
2: paper feed roll, 64: registration roll, 65: platen belt, 71: registration sensor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 DB09 ED12 EE03 EE05 EF09 2H076 BA17 BA24 BA64 BA67 BB04 3F102 AA01 AB01 BA02 BB02 DA08 EA03 FA02 3F343 FA03 FB02 FB03 FC13 FC14 FC15 GA01 GB01 GC01 GD05 LC18 MA26 MA54 MB14 MB15 MC08 MC17 MC22 5C062 AA02 AA05 AB32 AC11 BA00

Claims (4)

[Claims] 1. A platen to which a document to be scanned is fed, a scanning member for scanning a document image through the platen, a document tray on which a bundle of documents is set, and a plurality of documents set on the document tray. In an image input apparatus having a paper feed roll that separates and feeds a sheet at a time, and a pair of registration rollers that receives a document from the paper supply roll and feeds the document to the platen, the leading end of the document is sandwiched between the registration rolls. After that, while the driving of the paper feed roll is continued, at the latest, the drive of the paper feed roll is stopped until the trailing edge of the original document passes through the paper feed roll, and thereafter, the document is conveyed by the registration roll. An image input apparatus characterized in that a paper feed roll is driven to rotate with respect to a document. 2. The image input apparatus according to claim 1, wherein the drive stop timing of the paper feed roll is determined based on a document size. 3. The image input device according to claim 1, wherein the paper feed roll is driven for a predetermined time after the leading edge of the document is sandwiched between the registration rolls. 4. The image input device according to claim 1, wherein the document feed speed of the paper feed roll after the leading end of the document is sandwiched between the register rolls is set to be equal to or higher than the document feed speed of the register rolls.