JP2009179409A - Sheet feeding device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that light quantity adjustment operation is erroneously operated and a sheet cannot be detected when a sheet having high light transmittance exists in adjustment of light quantity of a sheet detection light sensor in a sheet feeding device. <P>SOLUTION: The sheet feeding device is provided with a pre-resist sensor for detecting the conveyed sensor, an ultrasonic double-feeding detecting sensor for detecting a double-feeding state of the conveyed sheet, and a control part for controlling the sheet feeding device and adjusting the light quantity of the pre-resist sensor based on detection signals of the respective sensors. When a document is detected with the usage of the ultrasonic double-feeding detecting sensor, light quantity adjustment operation of the pre-resist sensor S3 is not performed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding apparatus provided in an image reading apparatus, an image forming apparatus, or the like that includes a roller and conveys a plurality of originals one by one, such as a scanner, a facsimile machine, a copying machine, and a printer multifunction machine. Is.

  Conventionally, an image reading apparatus, an image forming apparatus, and the like are provided with a sheet feeding device, and a sheet stacked on a sheet stacking table is fed from the sheet stacking table by a pickup roller, and when the sheets are stacked and fed, the downstream feeding is performed. Sheets are separated one by one by a roller and a separation roller in pressure contact with the roller and fed into the apparatus main body. In order to detect that the sheet is fed into the apparatus main body, a lever type sheet detection sensor is often used. However, in the case of sheet detection by the lever type sheet detection sensor, since the conveyed sheet contacts the lever and presses the lever to detect the sheet, the timing of pressing the lever varies depending on the thickness of the sheet. There is also a risk that the sheet may be damaged when contacting the lever. In order to solve the above-mentioned problem, a light transmission type sheet detection sensor that detects a sheet in a non-contact manner has become widespread. When the light transmission type sheet detection sensor is used, there is a risk that individual differences occur in sensitivity depending on the light emitting element and the light receiving element to be used, resulting in erroneous detection. In addition, there is a risk of erroneous detection due to changes in characteristics of the light emitting element and the light receiving element due to temperature and aging. In order that the light transmission sensor can always detect the paper edge of the document accurately, the light intensity of the light emitting element is maintained so that the light reception output signal of the light receiving element of the light transmission sensor is within a certain range. A technique for performing a process of adjusting the above is disclosed (for example, see Patent Document 1).

Further, in the sheet feeding apparatus, even if it is attempted to convey the sheets one by one, a double feeding phenomenon may occur in which a part of the two or more sheets or the whole sheet is conveyed and overlapped. As a measure for preventing reading mistakes, an ultrasonic double-feed detection sensor using ultrasonic waves has become widespread.
Japanese Patent Laid-Open No. 9-323846

However, in the above conventional sheet feeding device, if a sheet such as a document having a high light transmittance remains on the optical path of the sensor when adjusting the light amount of the light transmission type sheet detection sensor, the light amount is adjusted to an optimum light amount. As a result, it may be impossible to detect a document having a high light transmittance. In such a case, the edge of the paper such as a document cannot be accurately detected, and the conveyance process cannot be performed correctly. In the present invention, when adjusting the light amount of the light transmission type sensor, the presence of the sheet is detected by using a sensor provided for other purposes, and the light amount is not adjusted when the sheet exists. Accordingly, it is an object of the present invention to provide a sheet feeding apparatus that can prevent mistakes in light amount adjustment of a light transmission type sensor and can accurately detect a paper edge of a document during conveyance of the document.

In order to achieve the above object, a sheet feeding apparatus according to the present invention includes a light transmissive sheet detecting unit having a light emitting unit and a light receiving unit disposed at a position facing the light emitting unit across a sheet conveying path, An ultrasonic multifeed detection unit having an ultrasonic transmission unit and an ultrasonic reception unit disposed at a position facing the ultrasonic transmission unit across the sheet conveyance path, and adjusting a light emission amount of the light emission unit. A light amount adjusting unit that performs a light amount adjusting operation, and the light amount adjusting unit does not perform the light amount adjusting operation when the ultrasonic multi-feed detecting unit detects the presence or double feeding of the sheet.

The sheet feeding apparatus according to the present invention further comprises sheet notifying means for notifying the presence of a sheet in response to detection of the sheet by the ultrasonic multifeed detecting means in the sheet feeding apparatus according to claim 1. And

The sheet feeding apparatus according to the present invention is the sheet feeding apparatus according to claim 1, wherein the light transmission type sheet detecting unit and the ultrasonic multifeed detecting unit are substantially arranged in the sheet conveying direction. It arrange | positions on the orthogonal line segment, It is characterized by the above-mentioned.

The sheet feeding device according to any one of claims 1 to 3, wherein the sheet feeding device according to any one of claims 1 to 3 detects a sheet by the light transmission type sheet detecting unit, and the ultrasonic multifeed detecting unit. When the sheet cannot be detected by the above, an abnormality notifying means for notifying at least one of the abnormality of the light transmission type sheet detecting means and the abnormality of the ultrasonic double feed detecting means is provided.

The sheet feeding device of the present invention performs detection of the presence of a sheet with high light transmittance without adding a new sensor by using a sensor mounted for the purpose of detection such as double feeding, It is possible to prevent an erroneous operation of the light amount adjustment of the light transmission type sensor that is performed before the start of the conveying operation or the like and to maintain the optimum state. As a result, it is possible to accurately detect the end of the conveyed sheet and accurately control the conveying process. Further, the presence of the sheet can be notified to prevent the sheet from being damaged, and the efficiency of the work can be greatly increased.

A document feeding apparatus which is an embodiment of a sheet feeding apparatus according to the present invention and an image reading apparatus provided with the document feeding apparatus in the apparatus body will be described with reference to the drawings. The sheet feeding device of each of the following embodiments is a document feeding device, but a recording material (sheet) on which an image is not formed is used as an image forming unit of the image forming apparatus instead of a document (sheet). It can also be used as a recording material feeding device for feeding. In addition, the present invention is not applied to the document feeder of the main body such as the image reading device, but applied to the document feeder of the document post-processing device that binds the document or punches the hole. You may make it improve the precision of the detection of the original document supplied to the processing apparatus.

FIG. 1 is a diagram showing a schematic configuration of an image reading apparatus 200 provided with a document feeding apparatus according to an embodiment of the present invention. The document table 1 is configured such that a plurality of documents as sheets to be read are stacked and can be moved up and down. The document detection sensor 3 detects the document on the document table 1. The pickup roller 4 sends out the document on the document table 1 from the document table 1. The feeding roller 6 is rotated by the feeding motor 8 in a direction in which the document is conveyed downstream. The separation roller 7 constantly receives a rotational force for returning the original document upstream from the separation motor 9 via a torque limiter or a clutch (not shown). In response, the feed roller 6 is allowed to follow and rotate by a torque limiter or a clutch and rotates. Then, when there are a plurality of originals, the separation roller 7 rotates in a direction to return the originals to the upstream side, and returns the overlapping originals.

The feeding roller 6 feeds the document downstream, and the separation roller 7 returns the document upstream, and the documents overlap and are fed into the nip portion between the feeding roller 6 and the separation roller 7. At this time, the upper document is fed downstream, the lower document is pushed back upstream, and the overlapping documents are separated and fed. Therefore, the feed roller 6 and the separation roller 7 constitute a separation / feed roller pair as a sheet separation / feed unit. For example, a separation belt roller pair may be used instead of the separation feed roller pair. The feed motor 8 rotates the feed roller 6. The separation motor 9 rotates the separation roller 7. The transport motor 10 can transport the separated and fed original from the original reading position to the discharge position, and at the same time, according to the optimum speed for reading the original and the resolution of the reading. You can change the speed. By adjusting the gap between the feeding roller 6 and the separation roller 7 or the pressure contact pressure of the feeding roller 6 against the separation roller 7 by the nip gap adjustment motor 11, the gap suitable for the thickness of the document or the thickness of the sheet is obtained. It is possible to separate and feed the document with a suitable pressure contact pressure.

The image reading unit 43 including the image reading sensors 14 and 15 reads the document while changing the interval at which the line scanning is repeated based on the reading speed and the resolution. The discharge sensor 16 detects that the document passes through the image reading unit 43 and is discharged to the paper discharge stacking unit 44. The registration rollers 17 and 18 temporarily stop conveying the document downstream, and correct the skew of the document. The transport rollers 20, 21, 22, and 23 transport the document to the paper discharge stacking unit 44. The two guide plates, the upper guide plate 40 and the lower guide plate 41, are used to feed a document that is nipped between the feeding roller 6, the separation roller 7, the registration rollers 17, 18, and the conveyance rollers 20, 21, 22, 23 and conveyed. It is designed to guide you.

The pre-feed sensor S1 detects the front end (downstream end) of the fed document. The post-feed sensor S2 detects the rear end (upstream end) of the fed document. The pre-registration sensor S3 and the ultrasonic double-feed detection sensor S4 are disposed upstream of the registration rollers 17 and 18, S3 indicates the leading edge of the fed document, and S4 indicates one fed document. And a double feed state in which two or more sheets are present are detected. In addition, the pre-registration sensor S3 and the ultrasonic double feed detection sensor S4 are arranged at positions substantially overlapping when viewed from the side of the apparatus as shown in FIG. The post-registration sensor S5 detects the leading edge of the document that is disposed downstream of the registration rollers 17 and 18 and is fed.

The upper unit 202 is rotatably supported by a support unit 50 provided in the main body 201, and the upper unit 202 can be rotated to an open position to open the conveyance path. The open / closed state of the upper unit 202 is detected by an open detection sensor (not shown). In the pre-registration sensor S3 and the ultrasonic double feed detection sensor S4, the light emitting part S3a and the transmission part S4a of the sensor are arranged in the main body 201, and the light receiving part S3b and the receiving part S4b are arranged in the upper unit 202. The respective parts of each sensor are arranged so as to face each other with the conveyance path in between when the upper unit 202 is returned from the open position to the original position and the apparatus is closed.

The controller 45 controls not only the document feeder but also the entire image reading apparatus 200. For example, the controller 45 controls each motor based on output signals from each sensor to rotate the rollers. Control. The control unit 45 notifies the state of the document feeder using a display panel 46 as a sheet notification unit and an abnormality notification unit. Further, the control unit 45 includes a detection unit that detects double feed using the ultrasonic double feed detection sensor S4, a detection unit that detects a sheet using the pre-registration sensor S3, and a light amount adjustment unit of the pre-registration sensor S3. is doing.

FIG. 2 is a view showing the positional relationship between the configuration of the pre-registration sensor S3 and the ultrasonic double feed detection sensor S4 and the document F1. Reference numeral S3a denotes a light emitting unit configured by an LED or the like. Reference numeral S3b indicates a light receiving portion formed of a light receiving element such as a phototransistor. Reference numeral S4a denotes an ultrasonic wave transmitting unit constituted by an element that transmits ultrasonic waves. Reference numeral S4b denotes an ultrasonic wave receiving unit configured with an element that receives ultrasonic waves. The light receiving unit S3b is disposed so as to face the light emitting unit S3a across the conveyance path of the document F1 so that the light emitted from the light emitting unit can be received. The ultrasonic wave receiving unit S4b is disposed so as to face the ultrasonic wave transmitting unit S4a across the conveyance path so that the ultrasonic wave transmitted through the document F1 can be received. In addition, the pre-registration sensor S3 and the ultrasonic double feed detection sensor S4 are arranged side by side on a line segment that is substantially orthogonal to the conveyance direction in the conveyance path.

FIG. 3 is a diagram for explaining the positional relationship among the feed roller 6, the pre-registration sensor S3, and the ultrasonic double feed detection sensor S4 when the document feeder is viewed from above. If it is assumed that the pre-registration sensor S3 and the ultrasonic double-feed detection sensor S4 are arranged in the positional relationship shown in FIG. 3A in the apparatus, if the document F1 exists in the conveyance path, S3 or S4 There is a risk that only one of the documents will be blocked by the document. On the other hand, as shown in FIG. 3B, in the sensor arrangement of this embodiment in which the pre-registration sensor S3 and the ultrasonic multifeed detection sensor S4 are arranged side by side in a direction substantially orthogonal to the conveyance direction, The existing document F1 blocks the pre-registration sensor S3 and the ultrasonic multifeed detection sensor S4 almost simultaneously. With this arrangement, it is possible to determine whether or not the document F1 exists at a position where the pre-registration sensor S3 is blocked using the detection result of the ultrasonic double feed detection sensor S4.

The light emitted from the light emitting unit S3a of the pre-registration sensor S3 is an optical path that travels to the light receiving unit S3b disposed at the opposite position across the conveyance path of the document F1. In the ultrasonic sensor S4, the ultrasonic wave transmitted from the ultrasonic wave transmitting unit in S4a proceeds to the ultrasonic wave receiving unit S4b disposed at the opposite position across the conveyance path of the document F1. In order to determine whether or not the document F1 being fed has reached a position that blocks the light path of the light emitted from the light emitting unit S3a of the pre-registration sensor and received by the light receiving unit S3b, the light receiving unit S3b receives and outputs the light. The detection unit that detects the sheet in the control unit 45 compares the received signal with the threshold value for document detection determination set in the control unit 45. When the received light signal becomes smaller than the threshold value, the detection unit detects that the fed document has reached the position of the pre-registration sensor S3, and the control unit 45 detects each drive unit and sensor in the apparatus. It is controlled to carry out the transfer operation.

The light emitting element and the light receiving element used for the pre-registration sensor S3 have individual differences in the amount of light emitted and the light receiving sensitivity. Also, since there are changes due to temperature and changes with time, it is difficult to maintain an optimum state for document detection when no adjustment is made. Therefore, in order to reliably detect the document fed using the pre-registration sensor S3, a light receiving output signal having a value within the range set by the control unit 45 is output from the light receiving unit S3b when there is no document. As described above, the amount of light emitted by the light emitting unit S3a is adjusted. At the time of adjusting the light amount of the pre-registration sensor S3, first, the control unit 45 sets the light emitting unit S3a to emit the maximum light amount, and the light emitting unit until the light receiving output signal value of the light receiving unit S3b becomes a value within the set range. The light amount adjustment is terminated when the amount of light emitted in S3a is reduced by the controller 45.

The ultrasonic sensor S4 transmits ultrasonic waves having a certain range of intensity, so that regardless of the type of document, the ultrasonic sensor S4a and the ultrasonic receiver S4b can detect ultrasonic waves when the document blocks between the ultrasonic transmitter S4a and the ultrasonic receiver S4b. It is known that the presence or absence of a document can be detected when the amplitude of the ultrasonic reception signal output from the receiving unit S4b is significantly reduced. Therefore, if ultrasonic waves having a certain range of intensity are transmitted, there is no need to make adjustments as in the pre-registration sensor S3. By the way, when the upper unit is in the open state, the light emitting part and the light receiving part of the pre-registration sensor S3, and the ultrasonic wave transmitting part and the ultrasonic wave receiving part of the ultrasonic sensor S4 are not disposed at opposing positions. The light quantity cannot be adjusted. Therefore, it is configured to detect whether or not the upper unit 202 is closed when starting the light amount adjustment by using an open detection sensor (not shown).

FIG. 4 is a flowchart illustrating an operation in the image reading apparatus 200 in which the control unit 45 adjusts the light amount of the pre-registration sensor by controlling the light emission amount of the light emitting unit while referring to the detection result of the open detection sensor. . The light quantity adjustment operation is performed by a CPU (not shown) provided in the control unit 45 executing a control program. As shown in FIG. 4, first, when a series of processes relating to the light amount adjustment of the pre-registration sensor S3 is started (step ST101), whether or not the upper unit 202 is in an open state is determined based on the detection result of the open detection sensor. Check. When it is detected that the upper unit 202 is in the open state (YES in step ST102), the light amount cannot be adjusted, so the light emission of the light emitting portion of the pre-registration sensor S3 is stopped (step ST103) and again. The open state of the upper unit is confirmed (step ST102). If it is detected that the upper unit 202 is in the open state, the light amount adjustment process may be abnormally terminated. If the upper unit 202 is returned to a predetermined position and the apparatus is closed (NO in step ST102), whether or not there is a document F1 that uses the ultrasonic sensor S4 to block the ultrasonic multifeed detection sensor S4. Is determined (step ST104). If the ultrasonic multifeed detection sensor S4 is used, the ultrasonic wave transmitted from the transmission unit S4a reaches the reception unit S4b, and the original is caused by the amplitude of the ultrasonic reception signal that is lowered when the fed original F1 blocks the path. The presence of F1 can be detected. That is, the amplitude of the ultrasonic reception signal is compared with the first reception signal threshold value and the second reception signal threshold value set by the control unit 45, and the amplitude is smaller than the first reception signal threshold value, When it is larger than the second received signal threshold, the presence of the document F1 can be detected. Note that the amplitude and the second threshold are compared, and when the amplitude is smaller than the second threshold, it is possible to detect a multi-feed state in which a plurality of documents F1 exist. When the ultrasonic double feed detection sensor S4 is used to detect the presence of the document F1 or the double feed state is detected (YES in step ST104), it is determined that the document F1 also blocks the pre-registration sensor S3 (step ST104a). Then, the light amount adjustment process is terminated (step ST104b). When it is determined that the document F1 does not exist using the ultrasonic double-feed detection sensor S4 (NO in step ST104), an actual light amount adjustment operation is started, and first, the maximum light amount is emitted from the light emitting portion of the pre-registration sensor S3 (step S104). ST105). In addition to the light amount adjustment operation, the control unit 45 uses the ultrasonic double-feed detection sensor S4 and controls each mechanism unit and sensor of the apparatus based on the detection result to perform the transport operation.

In step ST106, the light reception output signal value of the light reception unit S3b of the pre-registration sensor is acquired, and the acquired light reception output signal value is compared with the lower limit value of the range of the light reception output signal value set by the control unit 45 (step ST107). To do. If the light reception output signal value is smaller than the lower limit value (YES in step ST107), it is determined that there is a document that blocks light (step ST108), and the light amount adjustment process is terminated (step ST109). Since it is already determined in step ST104 that there is no document, the determination in step ST107 may be omitted. Here, the determination in step ST107 is performed in order to further increase the determination accuracy. If the received light output signal value is equal to or greater than the lower limit (NO in step ST107), it is determined that there is no document (step ST110), and the received light output signal value is set by the control unit 45. (Step ST111). If the light reception output signal value is equal to or greater than the upper limit value (YES in step ST111), it is determined that the emitted light is too strong, and the control unit 45 controls to reduce the light amount (step ST112), and returns to step ST106. The light amount adjustment process is continued. When the light reception output signal value is compared with the reception signal range upper limit value set by the control unit 45 (step ST111) and smaller than the upper limit value (NO in step ST111), the current light reception output signal value is the control unit. It is a value within the light reception output signal range set by 45, and it is determined that the light quantity is appropriate, and the light quantity adjustment process is terminated (step ST113). As described above, according to the procedure shown in steps ST102 and ST104 in the flowchart of FIG. 4, the control unit 45 determines whether the upper unit 202 is open and whether or not there is a document based on the detection results of the open detection sensor and the ultrasonic double feed detection sensor S4. Judging. When it is detected that the upper unit 202 is closed and no document is present, the light amount of the pre-registration sensor S3 is adjusted.

In the document reading apparatus, it is necessary to accurately detect the paper edge of the conveyed document in order to determine the document reading timing. As a means for this, the pre-registration sensor S3 whose light amount has been adjusted to an appropriate value as described above can accurately detect the paper edge of the conveyed document and output a detection signal to the control unit 45.

However, assuming an apparatus that does not determine the presence or absence of a document by ultrasonic waves, such as step ST104 described above, after the upper unit 202 is opened, a document having a high light transmittance exists in the document reading apparatus conveyance path. The upper unit 202 is closed, and the light amount adjustment of the pre-registration sensor S3 is performed in a state in which strong light is emitted from the light emitting unit. Then, since the light receiving unit can obtain the light reception output signal value within the range set by the control unit 45, it is assumed that the light amount adjustment is completed by treating the state where there is no document even though the document exists. . If the pre-registration sensor S3 completes the light amount adjustment in a state where a document having a high light transmittance exists in the transport path, the transported document is a light transmittance such as tracing paper when the transport operation is started. If the original is a high original, the pre-registration sensor S3 cannot detect the original. Further, in such an apparatus, since the light amount value of the pre-registration sensor S3 cannot be brought into an optimum state, the paper edge cannot be accurately detected even for a document having a low light transmittance. Further, in such an apparatus, when the control unit 45 starts a new document conveyance operation to a place where a document already remains on the conveyance path, the document remaining on the conveyance path is newly conveyed. The original may collide with the original in the conveyance path, and the original may be damaged or jammed.

On the other hand, in the sheet detection method using the ultrasonic double-feed detection sensor S4 employed in the present embodiment, the paper edge of the conveyed document cannot be accurately detected as in the pre-registration sensor S3, but the light transmittance is low. The presence of a high original can be detected. In other words, since the detection of the presence of a document being conveyed and the detection of double feeding are detected based on the attenuation amount of the ultrasonic wave emitted from the transmitter, the ultrasonic wave is attenuated and detected even for a document having a high light transmittance. Can do. By the way, even if there is a document having a high light transmittance so that the pre-registration sensor S3 can perform the light amount adjustment operation in a state where the document is blocking light, even if the ultrasonic sensor S4 can detect the presence of the document. The document thickness and light transmittance are unknown. For this reason, the optical pre-registration sensor S3 employed in this embodiment cannot be adjusted to an optimum light amount value that can accurately detect a document. Therefore, it is necessary to adjust the light amount of the pre-registration sensor S3 in a state where there is no document at the sensor installation position. In this embodiment, when the ultrasonic sensor S4 detects a document, the pre-registration sensor S3 performs light amount adjustment. I tried not to.

The image reading apparatus according to the present embodiment is added with a function for notifying the abnormal state of the pre-registration sensor S3. Since the pre-registration sensor S3 has a small sensor unit for detecting the paper edge of the document with high accuracy, the sensor unit may be blocked by dust such as paper dust or dust. When the sensor portion is blocked, the pre-registration sensor S3 enters an abnormal state in which the light amount adjustment operation cannot be performed. FIG. 5 illustrates the inside of the conveyance path performed by the control unit 45 based on the signals output from the pre-registration sensor S3 and the ultrasonic double feed detection sensor S4 in accordance with the light amount adjustment processing performed before the conveyance operation in the image reading apparatus 200. FIG. 6 is a flowchart showing processing such as determination / notification of presence / absence of a document and determination / notification of an abnormal state of a pre-registration sensor S3.

The light amount adjustment process similar to the process of FIG. 4 is started before the conveyance operation is started, and the presence or absence of a document in the conveyance path is checked by the ultrasonic multifeed detection sensor S4 in step ST201 (YES in step ST202). ), The control unit 45 notifies the display panel 46 that there is a document in the conveyance path, and interrupts the light amount adjustment (step ST203). When the ultrasonic double feed detection sensor S4 does not detect a document in the conveyance path (NO in step ST202), the pre-registration sensor S3 performs a light amount adjustment process similar to the process in FIG. 4 (step ST204). In step ST202, since the document is already detected by the ultrasonic double-feed detection sensor S4, the detection of the document by the ultrasonic double-feed detection sensor S4 may be omitted in the light amount adjustment processing performed here. When the pre-registration sensor S3 detects a document during the light amount adjustment process (YES in step ST204), it is considered that the pre-registration sensor S3 is in an abnormal state where the light amount adjustment cannot be performed due to a failure or paper jam. 45 determines that an abnormality has occurred in the pre-registration sensor S3, notifies the abnormal state using the display panel 46, and interrupts the light amount adjustment (step ST205). As the notification means, an LED such as a liquid crystal panel may be used, or a display device provided in a computer (not shown) connected to the image reading device may be used. Moreover, since abnormality of ultrasonic double feed detection sensor S4 is also considered, you may make it alert | report it.

When ultrasonic double feed detection sensor S4 does not detect a document in the transport path (NO in step ST202) and pre-registration sensor S3 does not detect a document in the transport path (NO in step ST204), the transport path Since there is no original in the document, after the light amount adjustment operation is continued (step ST206), the transport operation is started (step ST207). As described above, according to the procedure shown in the flowchart of FIG. 5, the image reading apparatus 200 detects the presence of the document by the ultrasonic sensor S4 before the start of the transport operation even when a document having a high light transmittance exists in the transport path. It is possible to reliably detect the light amount adjustment of the pre-registration sensor S3, thereby avoiding erroneous light amount adjustment.

In addition, the image reading apparatus 200 can adjust the light amount by detecting the document when the pre-registration sensor S3 adjusts the light amount, even though the ultrasonic multifeed detection sensor S4 does not detect the document before the conveyance operation is started. When there is no abnormality, it is possible to detect that the sensor optical path of the pre-registration sensor S3 is blocked by paper dust or dust, or that there is an abnormality such as deterioration or breakage of the sensor element of the pre-registration sensor S3. Yes. As described above, the image reading apparatus 200 uses both the pre-registration sensor S3 and the ultrasonic double-feed detection sensor S4, thereby reliably detecting the presence of the document even in a state where the document with high light transmittance exists in the conveyance path. To be able to do that.

Further, when the image reading apparatus 200 receives a read operation start command and detects a document in the transport path by the above process before the start of the transport operation, the start of the transport operation causes damage to the document or occurrence of a jam. In order to prevent this from happening, it is desirable that the controller 45 informs the feeding device of an abnormality and terminates the reading operation abnormally.

1 is a side sectional view showing a schematic configuration of an image reading apparatus including a document feeding apparatus that is an embodiment of a sheet feeding apparatus according to the present invention. The figure which shows the positional relationship of the pre-registration sensor with respect to the document to be fed, and the ultrasonic double feed detection sensor in the document feeder of the present invention. The figure for demonstrating the positional relationship of a feed roller, a pre-registration sensor, and an ultrasonic double feed detection sensor The flowchart which showed the light quantity adjustment process of the sensor before registration in the document feeder of this invention FIG. 5 is a flowchart showing a document path presence / absence determination process in the document feeder of the present invention.

Explanation of symbols

S3: Pre-registration sensor S4 ... Ultrasonic double feed detection sensor S5 ... Post-registration sensor F1 ... Original (sheet)
DESCRIPTION OF SYMBOLS 1 ... Document base 4 ... Pickup roller 6 ... Feeding roller 7 ... Separation roller 8 ... Feeding motor 9 ... Separation motor 10 ... Conveyance motor 43 ... Document reading Unit 45 ... Control unit 46 ... Notification unit (notification means)

Claims (6)

A light transmissive sheet detecting means having a light emitting means and a light receiving means disposed at a position facing the light emitting means across the sheet conveying path;
An ultrasonic multi-feed detecting unit having an ultrasonic transmitting unit and an ultrasonic receiving unit disposed at a position facing the ultrasonic transmitting unit across the sheet conveying path;
A light amount adjusting means for performing a light amount adjusting operation for adjusting the light emission amount of the light emitting means,
The sheet feeding device according to claim 1, wherein when the presence or double feeding of a sheet is detected by the ultrasonic double feeding detection unit, the light amount adjustment unit does not perform the light amount adjustment operation. The sheet feeding apparatus according to claim 1, further comprising a sheet notifying unit that notifies the presence of a sheet in response to the detection of the sheet by the ultrasonic multifeed detecting unit. 3. The sheet according to claim 1, wherein the light transmission type sheet detection unit and the ultrasonic multifeed detection unit are arranged on a line segment substantially orthogonal to the sheet conveyance direction. Feeding device. When the sheet is detected by the light transmission type sheet detection unit and the sheet cannot be detected by the ultrasonic double feed detection unit, the abnormality of the light transmission type sheet detection unit and the abnormality of the ultrasonic double sheet detection unit are detected. The sheet feeding apparatus according to any one of claims 1 to 3, further comprising an abnormality notifying unit that notifies at least one of them. A light transmissive sheet detecting means having a light emitting means and a light receiving means disposed at a position facing the light emitting means across the sheet conveying path;
An ultrasonic multi-feed detecting unit having an ultrasonic transmitting unit and an ultrasonic receiving unit disposed at a position facing the ultrasonic transmitting unit across the sheet conveying path;
A method for controlling a sheet feeding apparatus, comprising: a light amount adjusting means for performing a light amount adjusting operation for adjusting a light emission amount of the light emitting means,
When it is determined that the presence or double feed of the sheet is detected by the ultrasonic double feed detection unit, and the presence or double feed of the sheet is detected by the determination step, the light amount adjustment unit is And a step of stopping the light amount adjustment operation to be performed. A program for causing a computer to execute the control method of the sheet feeding device according to claim 5.

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