JP2010132396A - Sheet feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeder enabling reliable correction of the skew of sheets by adequately aligning the front ends of sheets to each other at a nip position between a pair of resist rollers even when slip occurs on a roller arranged on the upstream side of the pair of resist rollers which align the front ends of the sheets to each other. <P>SOLUTION: A time after the drive of a driving motor for driving a delivery roller and a feed roller is started but before a resist sensor in front of the pair of resist rollers detects the front end of the sheet is measured, and a time after the resist sensor detects the front end of the sheet but before the front end of the sheet abuts on the pair of resist rollers to stop the driving motor is controlled in accordance with the measured time. Thus, the deflection of the front ends of the sheets abutting on the pair of resist rollers is controlled to be constant to prevent an aligning failure of the front ends of the sheets. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet feeding device that feeds a sheet on a sheet feeding tray toward a predetermined processing position, and more specifically, an alignment mechanism that aligns the leading edge of a fed sheet and corrects the skew of the sheet. It is about.

    2. Description of the Related Art A document feeder, a copying machine, a printer, and the like are provided with a sheet feeder that feeds sheets such as sheet documents or copy sheets stacked on a sheet feed tray.

  A conventional sheet feeding device includes a feeding roller for feeding out a sheet on a sheet feeding tray, a separating unit including a feeding roller and a separation pad for separating and feeding the fed sheet into one sheet, and a separating unit And a pair of feed rollers that feed the sheet separated into one sheet toward the processing position.

  The sheet feeding apparatus configured as described above has an alignment function for correcting sheet skew. As a sheet feeding apparatus having this type of alignment function, for example, as described in Patent Document 1, a sheet separated by a separating unit including a sheet feeding roller and a separation pad is abutted against a registration roller. Matching configurations that match are generally known.

  Specifically, a sheet detection sensor is provided in front of the registration roller, and the sheet feeding roller is driven by a fixed feed amount from the time when the sheet detection sensor detects the leading edge of the sheet. As a result, the leading edge of the sheet hits the nip point of the stopped pair of registration rollers by a predetermined amount of contact, and a bend (loop) is formed. This operation aligns the leading edge of the sheet. Thereafter, by driving the registration roller, the registration roller pair feeds the sheet to the downstream side with the leading edge of the sheet abutted against the nip portion interposed therebetween. By these operations, the skew of the sheet is corrected.

JP 2004-106995 A

  However, the feeding roller for feeding out the original and the paper feeding roller for separating and feeding the original into one sheet change the conveying force due to changes in the material and surface over time and wear due to the usage frequency. The amount of slip between the seat and the sheet also changes over time. In recent years, the types of sheets to be handled are diversified, and the amount of slip between the roller and the sheet varies depending on the type of the sheet. Further, the amount of abutment against the registration roller pair varies due to a change or difference in slippage between the feeding roller and the sheet and between the sheet feeding roller and the sheet, and the leading edge of the sheet cannot be properly aligned. Problems arise. When such a problem occurs, the feeding roller, the paper feed roller, and the separation pad must be frequently replaced, and handling thereof becomes complicated. In addition, there is a problem that the feeding roller, the paper feeding roller, and the separation pad are exchanged regardless of the life of the roller.

  Further, in order to solve the above-described problem caused by the variation in the abutting amount, the maximum value of the variation is obtained as experimental data in advance, and the feed amount of the constant sheet feeding roller is set to the maximum value of variation from the time when the leading edge of the sheet is detected It can be set to match. However, in this case, the contact time of the sheet with the pair of registration rollers becomes long, and the productivity is lowered. In addition, depending on the condition of the roller and the type of the sheet, the sheet will be pressed against the registration roller pair more than necessary, so the sheet may be bent, or the leading edge of the sheet may pass through the nip position of the registration roller pair, resulting in poor alignment. May occur.

  The present invention has been made in view of the above-described problems, and even when slippage occurs on a roller disposed on the upstream side of the alignment position, the leading edge of the sheet is properly positioned at the nip position of the registration roller pair. It is an object of the present invention to provide a sheet feeding apparatus that can align and reliably correct sheet skew.

  In order to achieve the above object, the present invention provides a paper feed tray for stacking sheets, a feed roller for feeding out the sheets on the paper feed tray, a paper feed roller for feeding the sheets fed by the feed roller, A separating member that is pressed against the sheet feeding roller to separate the sheet, a pair of registration rollers that align the leading ends of the sheets fed by the sheet feeding roller, and a feeding roller and a sheet feeding roller In the sheet feeding apparatus, the detecting unit is disposed between the sheet feeding roller and the registration roller, and detects the leading edge of the sheet, and the detecting unit from the time when the driving unit starts driving. Measuring means for measuring the time until the leading edge of the sheet is detected, and control means for controlling the driving time of the sheet feeding roller by the driving means based on the measurement result of the measuring means , With.

  The time from when the driving unit starts driving until the detecting unit detects the leading edge of the sheet is measured, and based on the measurement result, the leading end of the sheet is detected by the detecting unit and then abuts against the registration roller pair to bend. Since the drive time of the drive means until formation is controlled, it is possible to adjust so that the amount of deflection formed by striking the pair of registration rollers is always constant, and it is possible to prevent misalignment of the leading edge of the sheet.

  FIG. 1 is a cross-sectional view showing an entire document feeding device to which the sheet feeding device of the present invention is applied and an image reading device on which the document feeding device is mounted. FIG. It is sectional drawing which shows a part. The configuration of the document feeder and the image reading apparatus on which the document feeder is mounted will be described below with reference to FIGS.

  Reference numeral 10 denotes a document feeder mounted on the image reading apparatus 1, and the document feeder 10 conveys a sheet document so as to pass through the upper surface of the contact glass 2 of the apparatus body 1.

  The image reading apparatus 1 includes a reading unit including a light source 3, a plurality of mirrors 4, a lens 5, and a reading element 6. This reading means irradiates a sheet original conveyed with light by a light source 3 such as a lamp through a contact glass 2. Then, the reflected light from the sheet original is reflected by the mirror 4 and guided to the reading element 6 such as a CCD through the lens 5. The light guided by the mirror 4 and the lens 5 is photoelectrically converted by the reading element 6 to read the sheet original image. That is, the upper surface of the contact glass 2 constitutes a reading unit of the apparatus main body 1. The apparatus body 1 also includes a contact glass 7 having an area on which a sheet document can be placed. The sheet document placed on the upper surface of the contact glass 7 by opening and closing the document feeder 10 is used as a light source 3 and a mirror 4. By moving in the sub-scanning direction, the image of the sheet original can be read through the contact glass 7.

  The document feeder 10 includes a sheet feeding tray 15 on which a plurality of sheet documents can be placed, and a sheet feeding unit that separates the sheet documents on the sheet feeding tray 15 one by one toward the contact glass 2 ( (Feeding means) 11, a transport unit 12 that allows the sheet document to pass along the upper surface of the contact glass 2, a discharge unit 13 that receives and discharges the sheet document that has passed through the upper surface of the contact glass 2, and is discharged from the discharge unit 13. And a paper discharge tray 16 for storing a sheet original from which an image to be read is stored. Further, the document feeder 10 includes a switchback unit 14 that switches back a sheet document ejected from the upper surface of the contact glass 2 by the ejecting unit 13, and again feeds the sheet document to the feeding unit 11 and feeds it to the upper surface of the contact glass 2. It has. Here, the paper feed tray 15 is inclined at a certain angle and is disposed with a space above the paper discharge tray 16.

  The sheet document placed on the sheet feeding tray 15 is regulated by the side guide 17 that regulates the side portion thereof, and the leading end is regulated by the stopper member 60. An empty sensor S4 for detecting the presence or absence of a sheet document on the sheet feed tray 15 is provided upstream of the stopper member 60 in the sheet feeding direction.

  The sheet feeding unit 11 descends and comes into contact with the uppermost surface of the sheet document on the sheet feeding tray 15, and a feed roller 18 that can be raised and lowered to feed the sheet document, and a sheet feeding sheet that is fed by the feed roller 18. Separating means composed of a separating member 20 comprising a friction pad for passing the roller 19 and the uppermost sheet document through only one sheet and blocking the feeding of the second and subsequent sheet documents, and the separating means into one sheet A pair of registration rollers 21 that are sent to the downstream side after abutting and aligning the leading edge of the separated sheet document, and feeding the sheet document along the sheet feeding path 25.

  The conveyance unit 12 includes a pair of carry-in rollers 22 for supplying a sheet document to the contact glass 2 on the upstream side of the contact glass 2 and a pair of carry-out rollers 23 for discharging the sheet document from the contact glass 2 on the downstream side. The document is conveyed along the conveyance path 26.

  The paper discharge unit 13 and the switchback unit 14 share a part on the paper discharge tray 16 side, and a paper discharge roller pair 24 for discharging the sheet document to the paper discharge tray 16 is provided. The paper discharge roller pair 24 rotates in the forward direction when a sheet document is discharged to the paper discharge tray 16. Further, when reading both sides of the sheet document, the sheet document roller pair 24 rotates in the reverse direction with the rear end side of the sheet document nipped in order to reverse the sheet document and supply it to the contact glass 2 again. Control is performed so that the sheet document is switched back and sent to the sheet feeding unit 11.

  That is, in the single-side mode for reading one side of a sheet original, the sheet original is discharged from the paper discharge path 27 onto the paper discharge tray 16, and in the double-side mode for reading both sides of the sheet original, the sheet original is switched back in the paper discharge path 27. It returns to the middle of the paper feed path 25 via the switchback path 28.

  FIG. 3 is a control glock diagram. Each detection sensor will be described with reference to the block diagrams of FIGS. 1, 2, and 3. The paper feed tray 15 is provided with a plurality of sensors S1 and S2 for detecting the length size of the sheet document. Further, the width direction of the sheet document placed on the sheet feed tray 15 is detected by a volume VR whose output changes depending on the amount of movement of the side guide 17, and the detection result of the sheet document width and a plurality of sensors S1 and S2 are used. The sheet document size is determined based on the detected sheet document length. Further, in the path for guiding the sheet document, an empty sensor S4 as detection means for detecting that the sheet document is placed on the sheet feed tray 15 described above, and the sheet document fed through the sheet feed path 25. A registration sensor S5 for detecting the edge of the sheet document, a lead sensor S6 for detecting the edge of the sheet document provided in front of the contact glass 2, and a discharge sensor S7 for detecting the edge of the sheet document discharged from the contact glass 2, respectively. Is provided. These sensors S1 to S7 are connected to a control unit 100 including a CPU that controls the driving of the entire apparatus, and the motors MT1 and MT2 are driven based on detection signals from the sensors.

  The registration roller pair 21 aligns the leading edge of the sheet document by causing the leading edge of the sheet document to abut the nip position, and forms a deflection on the leading edge side of the sheet document. Is configured to correct. In the present embodiment, the details will be described later, but from the time when the paper feed motor MT1 that drives the feed roller 18 and the paper feed roller 19 is driven, that is, from the time when the feed roller 18 and the paper feed roller 19 start driving. The time until the leading edge of the sheet is detected by the registration sensor S5 is measured, and the leading edge of the sheet document hits the nip position of the registration roller pair 21 after the registration sensor S5 detects the leading edge of the sheet document based on the measurement result. Thus, the driving time (alignment time) of the sheet feeding motor MT1 until the sheet document is bent is adjusted so that the deflection of the sheet document is always constant.

  The document transport control operation of the document feeder configured as described above will be specifically described.

  First, the single-side mode for reading one side of a sheet original will be described with reference to the timing chart of FIG. 4. First, the sheet original is placed (set) on a paper feed tray in contact with a stopper 60 serving as a leading edge restricting means. When it is detected that the empty sensor S4 is ON, that is, when a sheet document is placed on the sheet feed tray 15, and a sheet feed command is received, the restriction of the sheet document of the stopper 60 is released, and the sheet feed motor MT1. Is driven forward. Accordingly, the feeding roller 18 and the paper feeding roller 19 are rotated in the sheet original feeding direction, and the sheet original is fed. At this time, the registration roller pair 21 does not rotate by the action of the one-way clutch.

  Subsequently, the alignment operation of the leading edge of the sheet document is executed. In the alignment operation, the sheet feeding motor MT1 is temporarily stopped after the alignment time tx set from the time point when the registration sensor S5 detects the leading edge of the fed sheet document. As a result, the leading edge of the sheet document is brought into contact with the nip portion of the registration roller pair 21 to form a deflection, and the leading edge of the sheet document is aligned.

  Then, after the alignment operation is completed, when a predetermined time t1 elapses, the paper feed motor MT1 is driven to rotate in the reverse direction, and at the same time, the transport motor MT2 is driven. At this time, the feeding roller 18 rises to a position away from the sheet document, the drive of the paper feed roller 19 is cut off by the action of the one-way clutch WO1, and the registration roller pair 21 is rotated in the feeding direction.

  By rotating the motors MT1 and MT2, the registration roller pair 21, the carry-in roller pair 22, the carry-out roller pair 23, and the paper discharge roller pair 24 are rotationally driven, and the sheet document is conveyed from the paper feed path 25 to the conveyance path 26. The contact glass 2 passes over the contact glass 2 by a pair of carry-in rollers 22, a carry-out roller pair 23, and a paper discharge roller pair 24. At this time, the surface (one side) of the sheet original is sub-scanned and read by the reading means at the reading position on the contact glass 2. In this process, the sheet feeding motor MT1 stops after the time t2 when the leading edge of the sheet document is securely nipped by the conveyance roller 22 from the time when the lead sensor S6 detects the leading edge of the sheet document.

  Then, the read sheet document is pushed up the tip of a flapper 29 arranged so as to block the paper discharge path 27 at the tip, and is conveyed onto the paper discharge tray 16 by the paper discharge roller pair 24. It should be noted that after the trailing edge of the sheet document is detected by the registration sensor S5, when a predetermined time t3 has elapsed, the sheet feeding motor MT1 is driven to rotate forward again to start feeding the next sheet document.

  Next, the duplex mode for reading both sides of a sheet document will be briefly described.

  When the empty sensor S4 detects that the sheet document is placed on the sheet feed tray 15, the sheet document is placed on the contact glass 2 by the feeding roller 18, the sheet feed roller 19, and the resist roller pair 21 as in the single-side mode. The surface is read by the reading means and guided to the paper discharge path 27.

  Thereafter, in this double-sided mode, a switchback reversing operation is executed in order to reverse the front and back of the sheet document and re-feed the sheet document onto the contact glass 2 again. In this switchback reversal operation, first, when the trailing edge of the sheet document reaches a predetermined position passing through the flapper 29, the driving of the transport motor MT2 is stopped. At this time, the rear end of the sheet document is nipped by the pair of discharge rollers 24 and stopped.

  Thereafter, the transport motor MT2 is driven in reverse. As a result, the sheet discharge roller pair 24 rotates in the reverse direction, the sheet document is switched back, and the switchback path along the sheet document guide surface of the flapper 29 that has moved to a position that closes the sheet discharge path 27 as the sheet document passes. 28 is guided. When the leading edge of the sheet document guided to the switchback path 28 reaches the nip portion of the registration roller pair 21, the sheet feeding motor MT2 is driven in reverse to refeed the sheet document. As a result, the registration roller pair 21 is rotated. When the leading edge of the sheet document is securely nipped between the registration roller pair 21, the transport motor MT2 is driven to rotate forward. As a result, the carry-in roller pair 22 and the carry-out roller pair 23 are rotated, and at the same time, the paper discharge roller pair 24 is rotated in the paper discharge direction.

  By this series of operations of the registration roller pair 21, the carry-in roller pair 22, the carry-out roller pair 23, and the paper discharge roller pair 24, the sheet document is reversed and fed and conveyed along the paper feed path 25 and the transport path 26. . Then, it passes over the contact glass 2. At this time, the back side of the sheet document is sub-scanned and read by the reading unit.

  After that, the sheet document guided through the sheet discharge path 27 is again subjected to the switchback inversion operation in order to discharge the sheet document to the sheet discharge tray 16 in the same page order. Then, the switchback reversal operation is executed, and the sheet document whose page order is aligned is discharged from the discharge path 27 to the discharge tray 16. Even in the switchback reversing operation for page alignment, the sheet document is conveyed onto the contact glass 2, but here, the sheet document is not read and scanned.

  In this embodiment, the number of drive pulses of the paper feed motor MT1 is used to measure the time, and the time is measured by counting the number of drive pulses of the paper feed motor MT1. Therefore, the time used for the above-described control for feeding the sheet document is equal to the driving amount of the sheet feeding motor MT1, that is, the rotation amounts of the feeding roller 18 and the sheet feeding roller 19.

  Here, the feeding roller 18 and the paper feeding roller 19 are caused by various factors such as wear due to use, change in friction coefficient due to environment, change in material over time, thickness of sheet original, and type of sheet original. The slip amount between the sheet feeding roller 19 and the sheet document is different. If the slip amount is large, the leading edge of the sheet document does not sufficiently come into contact with the nip position of the registration roller pair 21 and alignment failure occurs.

  In order to solve such a misalignment, in the present embodiment, as described above, during the aligning operation, adjustment is performed so that the bending formed when the leading end of the sheet hits the registration roller pair 21 is always constant. Adjustment is being performed. FIG. 5 is a conceptual diagram for explaining the adjustment operation, and FIG. 6 is an operation flowchart of the adjustment operation. 7A is a timing chart showing the alignment operation when there is no slippage between the roller and the sheet document, and FIG. 7B is a timing chart showing the alignment operation when the roller and the sheet document slip. FIG. The adjustment operation will be described below based on FIG. 5, FIG. 6, and FIG.

  As shown in FIG. 5, in this apparatus 10, the time from when the paper feed motor MT1 is activated and the feed roller 18 and the paper feed roller 19 start to rotate until the registration sensor S5 detects the leading edge of the sheet original. And a RAM 100 for storing a reference driving pulse number (reference driving time) Ps and a reference matching pulse number (reference matching time) ts. The measuring means measures the time by counting the number of drive pulses of the paper feed motor MT1.

  The reference operation pulse number Ps is a drive pulse number calculated in advance assuming that there is no slip between the feeding roller 18 and the sheet feeding roller 19 and the sheet document. The reference operation pulse number Ps includes a first reference drive pulse number Ps1 corresponding to the distance from the sheet document leading edge regulating position P1 by the stopper 60 to the detection position P3 of the registration sensor S5, the sheet feeding roller 19, and the separating member 20. And a second reference drive pulse number Ps2 corresponding to the distance from the pressure contact position P2 to the detection position P3 of the registration sensor S5, both of which are stored in the RAM. Further, the reference alignment pulse number ts is an alignment pulse number calculated in advance assuming that there is no slip between the feeding roller 18 and the paper feed roller 19 and the sheet original, and the alignment pulse number ts is calculated from the detection position of the registration sensor S5. Add the sheet feed pulse number tsb at which the leading edge of the sheet document comes into contact with the nip position of the registration roller pair 21 and a predetermined deflection is formed on the sheet to the sheet feed pulse number tsa corresponding to the distance to the nip position of the pair 21. The number of pulses. In FIG. 5, the feed amount (deflection amount) according to the sheet feed pulse number tsb is shown by a straight line.

  If the sheet document is the first sheet, the number of pulses Px measured by the timer TM is compared with the first reference driving pulse number Ps1, and the slippage between the feeding roller 18 and the sheet feeding roller 19 and the sheet document is detected. The amount ΔPx is calculated. On the other hand, for the second and subsequent sheets, the number of pulses Px measured by the timer TM is compared with the second reference driving pulse number Ps2, and the slip amount ΔPx between the feeding roller 18 and the sheet feeding roller 19 and the sheet document is calculated. To do.

  The difference in the reference drive pulse number Ps between the first and second sheets is that the leading edge of the first sheet is sent out from the restriction position by the stopper 60, and the second and subsequent sheets are separated from the paper feed roller 19. This is because the members 20 are separated at the press contact position of the member 20 and are sent out from the press contact position.

  Then, an alignment time tx from when the registration sensor S5 detects the leading edge of the sheet document based on the slip amount ΔPx to when the leading edge of the sheet document hits the nip position of the registration roller pair 21 and bending is formed on the sheet document, Adjust so that the deflection of the sheet document is always constant.

  As a result, the amount of bending during the alignment operation can always be made constant regardless of the wear of the feeding roller 18 and the paper feed roller 19 and the type of the sheet document, so that the alignment of the leading edge of the sheet document is ensured.

  This adjustment operation will be described in detail with reference to the control flowchart of FIG. 6. The paper feed motor MT1 is driven to rotate forward based on a paper feed command, and at the same time, counting of drive pulses of the paper feed motor MT1 is started (ST1 to ST2). Then, when the registration sensor S5 detects the leading edge of the sheet document, the drive pulse count is finished, and the count value (number of pulses) Px is stored in the ROM (ST3 to ST4).

  Next, if the sheet document to be fed out is the first sheet document, the first reference drive pulse number Ps1 and the count value Px corresponding to the distance from the restriction position by the stopper 60 at the front end of the sheet document to the detection position of the registration sensor S5. And the pulse difference (slip amount) ΔPx is calculated (ST5 to ST6). On the other hand, for the second and subsequent sheets, the second reference drive pulse number Ps2 corresponding to the distance from the pressure contact position of the paper feed roller 19 and the separating member 20 to the detection position of the registration sensor S5 is compared with the count value Px. The pulse difference ΔPx is calculated (ST5, ST7).

  Next, the pulse difference ΔPx calculated in step 6 or step 7 is compared with a predetermined set value X. When the pulse difference ΔPx is larger than the set value X, a value obtained by adding a predetermined adjustment value Δtx to the initial reference matching pulse number ts is set as the matching pulse number tx (ST8 to ST9). As a result, as shown in FIG. 7B, the sheet feeding motor MT1 is driven by the alignment pulse number tx obtained by adding the adjustment value Δtx to the reference alignment pulse number ts, and the alignment operation is executed.

  When the pulse difference ΔPx is smaller than the set value X, the initial reference matching pulse number ts is set as the matching pulse tx. That is, in this case, it is determined that the sheet document does not slip with the feeding roller 18 and the sheet feeding roller 19, and the alignment operation is executed at the timing shown in FIG. Note that the set value X is a value set in consideration of a minute slip that does not affect the alignment, a time lag between the driving of the driving motor MT1 and the rotation of the feeding roller 18 and the paper feeding roller 19, and the like.

  This adjustment operation is performed for each sheet document that is fed out. As a result, even when sheet documents having different thicknesses or different types of sheet documents are mixed in the stacked sheet document on the sheet feed tray 15, the leading edge of the sheet document is reliably aligned.

  The adjustment value Δtx added to the initial reference matching pulse number ts includes the ratio of the first reference driving pulse number Ps1 or the second reference driving pulse number Ps2 and the pulse difference ΔPx, and the initial reference matching time ts. The adjustment value Δtx is calculated and set so that the ratio of the adjustment value Δtx is the same. That is, the adjustment value Δtx is calculated from the following arithmetic expression.

Ps: ΔPx = ts: Δtx
Δtx = ΔPx × ts / Ps
Of course, without calculating the adjustment value Δtx as described above, a value corresponding to the pulse difference ΔPx is selected from a plurality of values stored in the ROM, and the selected reference value is used as the adjustment value Δtx. The number of matching pulses tx may be set by adding to the number ts.

  According to the above-described embodiment, the alignment operation is always performed with a certain amount of deflection, so that the leading edge of the sheet is reliably aligned. Further, since the leading edge of the sheet document can be aligned with the minimum amount of deflection necessary for alignment, the productivity of sheet document processing is improved.

  Further, the time Px from the time when the sheet feeding motor MT1 is activated to the time when the registration sensor S5 detects the leading edge of the sheet document is compared with preset reference times Ps1 and Ps2, and the matching time is determined based on the comparison result. Since tx is adjusted, appropriate matching is achieved without adding new parts.

  Further, according to the present embodiment, the time Px from when the paper feed motor MT1 starts to drive until the registration sensor S5 detects the leading edge of the sheet document is measured by the timer MT, and the sheet document is the first sheet. In this case, the first reference driving time Ps1 corresponding to the distance from the restriction position of the leading edge of the sheet document by the stopper 60 to the detection position of the registration sensor S5 is compared with the time Px measured by the timer MT, while the sheet document is In the case of the second and subsequent sheets, the second reference drive time Ps2 corresponding to the distance from the pressure contact position between the paper feed roller 19 and the separating member 20 to the detection position of the registration sensor S5 and the time Px measured by the timer MT Therefore, the amount of bending during the alignment operation can always be made constant for all the sheet documents stacked on the sheet feed tray 15, and the leading edge of the sheet document Match is made with certainty.

1 is a cross-sectional view illustrating an entire document feeding device to which a sheet feeding device of the present invention is applied and an image reading device on which the document feeding device is mounted. FIG. FIG. 3 is a cross-sectional view showing a main part of the document feeder according to the present invention. FIG. 3 is a control block diagram illustrating a control system of the document feeder according to the present invention. FIG. 6 is a control timing chart showing the operation of the document feeder according to the present invention. It is a conceptual diagram for demonstrating the adjustment operation | movement which concerns on this invention. It is an operation | movement flowchart figure of the adjustment operation | movement which concerns on this invention. It is a timing chart figure which shows the matching operation | movement performed by the adjusted matching time which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Image reader 10 Document feeder 2 Contact glass 15 Paper feed tray 18 Feeding roller 19 Paper feed roller 20 Separating member 21 Registration roller pair 22 Carry-in roller pair 23 Carry-out roller pair 60 Stopper 100 Control part MT1 Paper feed motor S5 Alignment sensor S6 Read sensor TM Timer Ps1 First reference drive pulse number Ps2 Second reference drive pulse number Px Number of pulses (count value)
ΔPx Pulse difference (slip amount)
ts Reference matching time tx Matching time Δtx Adjustment value X Setting value

Claims (4)

A sheet feeding tray for stacking sheets, a feeding roller for feeding out the sheet on the sheet feeding tray, a sheet feeding roller for feeding the sheet fed by the feeding roller, and a sheet pressed against the sheet feeding roller A separating member that separates, a registration roller pair that aligns the leading edge of the sheet by abutting the leading edge of the sheet fed by the feeding roller, and a driving unit that drives the feeding roller and the feeding roller; In a sheet feeding device equipped with
A detection unit that is disposed between the sheet feeding roller and the registration roller and detects the leading edge of the sheet, and measures a time from when the driving unit starts driving until the detection unit detects the leading edge of the sheet. Measuring means for comparing, a comparing means for comparing the measuring time of the measuring means with a predetermined reference time, a control means for controlling the driving time of the paper feed roller by the driving means based on the comparison result of the comparing means, A sheet feeding apparatus comprising: A storage means for storing a plurality of the predetermined reference times; and a selection means for selecting any one of a plurality of reference times stored in the storage means according to the number of documents fed. The sheet feeding apparatus according to claim 1, wherein the sheet feeding device compares a measurement time of the measurement unit with a reference time selected by the selection unit. A regulation means for regulating the leading edge of the sheet placed on the sheet feeding tray and releasing the regulation of the sheet before the feeding roller feeds the document;
The selection means selects a first reference time corresponding to the distance from the restriction position of the leading edge of the sheet by the restriction means to the detection position of the detection means when the sheet to be fed is the first sheet, and the comparison The sheet feeding apparatus according to claim 2, wherein the unit compares the first reference time selected by the selection unit with a measurement result by the measurement unit. The selection means selects a second reference time corresponding to the distance from the contact position between the paper feed roller and the separating member to the detection position of the detection means when the second and subsequent sheets are fed. The sheet feeding apparatus according to claim 3, wherein the comparison unit compares the second reference time selected by the selection unit with a measurement time by the measurement unit.