JP2009029567A - Automatic document feeder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic document feeder, capable of shortening the time from setting of the document on a document table to start of copy action. <P>SOLUTION: The automatic document feeder is provided with a movable document table 3 on which a document bundle 1 comprising a plurality of documents is placed, a pickup roller 7 to separate the uppermost document to transfer from the document bundle 1 placed on the movable document table 3, and a bottom plate raising motor 105 to raise and lower the movable document table 3 in such a way that the uppermost document of the document bundle 1 gets in contact with, or separates from the pickup roller 7. A controller 100 is also provided to raise and lower the movable document table 3 while varying drive speed of the bottom plate raising motor 105 in such a way that the uppermost document of the document bundle 1 gets in contact with the pickup roller 7 with a predetermined pressure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an automatic document conveying device, and more particularly to an automatic document conveying device that separates and conveys a document at the top of a document bundle placed on a document table one by one.

  In general, in an automatic document feeder, in order to separate and transport the uppermost document of the document bundle placed on the document table one by one, a part of the document table is raised and the uppermost document bundle is In some cases, the separation member is brought into contact with the original document with an appropriate pressure.

  Conventionally, this type of automatic document feeder switches whether to raise the document table as a paper feed preparation operation according to the status of the image forming apparatus main body and whether or not the mixed loading mode is set. An apparatus that shortens the time required for copying is known (for example, see Patent Document 1).

  In addition, there is known a technique in which the time from the detection of a document set to the first copy is shortened by arbitrarily setting the lowered position of the document table (see, for example, Patent Document 2). .

In addition, after the original is placed on the original table, the upper surface of the original is moved to a standby position below the upper limit position by a predetermined distance from the upper limit position for a predetermined time, and the original is placed on the original table. There is known a technique that shortens the time from the paper feed instruction to the first copy regardless of the amount (for example, see Patent Document 3).
JP 2000-53255 A Japanese Patent Laid-Open No. 11-352608 Japanese Patent No. 3661783

  However, in the conventional automatic document feeder as described above, as the number of documents that can be stacked on the document table has increased in recent years, the document is separated from the position where the document table is lowered when the document bundle is placed. Since the distance to the raised position of the document table for transporting is increased, it takes a longer time to raise the document table, and the copy operation is started after the document is set on the document table. There was a problem that it took a long time to do.

  The present invention has been made to solve the above-described conventional problems. By shortening the time required for the original table to rise to the paper feedable position after setting the original on the original table, It is an object of the present invention to provide an automatic document feeder that can shorten the time from when a document is set on a document table to when a copy operation is started.

  An automatic document feeder according to the present invention includes a document placing unit for placing a document bundle composed of a plurality of documents, and a document on the top of the document bundle is separated from the document bundle placed on the document placing unit. An automatic document feeder comprising: a separating and conveying unit that conveys the document; and a driving unit that raises and lowers the document placing unit so that the uppermost document of the bundle of documents contacts and separates from the separating and conveying unit. In the apparatus, drive control for raising and lowering the document placing means while changing the drive speed of the drive means so that the uppermost document of the document bundle contacts the separation conveying means with a predetermined pressure It is characterized by having means.

  With this configuration, the driving unit is driven at a high speed so that the document placing unit rapidly rises, and the driving unit is stopped before stopping the document placing unit so that the document placing unit finishes rising at an appropriate position. By rotating at a low speed, it is possible to shorten the time from when the document is set on the document placing means to when the copy operation is started. Further, since the document placing means finishes rising at an appropriate position, stable document separation and conveyance can be performed.

  Further, the automatic document feeder according to the present invention is characterized in that the drive control means changes the driving speed of the driving means in accordance with a change in the document stack placement status in the document placement means. .

  With this configuration, the drive unit is rotated at a high speed or a low speed according to the presence or absence of a document bundle in the document placing unit, so that the copy operation is started after the document is set on the document placing unit. Time can be shortened.

  In the automatic document feeder according to the present invention, the drive control unit separates all of the bundles of documents placed on the document placing unit by the separation carrying unit, and the document placing unit is in the raised position. The driving means is driven at a high speed so that the document placing means descends rapidly when conveyed.

  With this configuration, it is possible to shorten the time from when the document placing unit descends until a new document bundle is placed.

  In the automatic document feeder according to the present invention, when the drive control unit is in a state where the document placing unit is in the lowered position and a document bundle is placed on the document placing unit, the document placing unit The driving means is driven at a high speed so that the temperature rises rapidly.

  With this configuration, it is possible to shorten the time from when the document is set on the document placing unit to when the copy operation is started.

  The automatic document feeder according to the present invention further comprises weight detection means for detecting the weight of the document bundle placed on the document placement means, and the drive control means detects the weight detected by the weight detection means. Accordingly, the drive speed of the drive means is changed.

  According to this configuration, the document placing unit can be moved at an appropriate speed according to the weight of the document bundle placed on the document placing unit.

  In the automatic document feeder according to the present invention, the drive control unit drives the drive unit at a low speed when the weight detected by the weight detection unit is equal to or greater than a threshold value.

  With this configuration, when the bundle of documents placed on the document placing means is heavy, the document placing means can be raised while maintaining a sufficient driving force at a low speed.

  The automatic document feeder according to the present invention is characterized in that the drive control means drives the drive means at a high speed when the weight detected by the weight detection means is less than a threshold value.

  With this configuration, when the bundle of documents placed on the document placing means is light, the document placing means is raised at a high speed in a short time, and the copy operation is started after the document is set on the document placing means. The time can be shortened.

  The automatic document feeder according to the present invention is characterized in that the document placing means includes at least one weight detecting means.

  With this configuration, the movement of the document placing unit can be controlled in accordance with the weight of the document bundle placed on the document placing unit.

  In the automatic document feeder according to the present invention, the drive control unit causes the document placing unit to wait for the uppermost document of the document bundle to contact the separating and conveying unit once with a predetermined pressure. The drive means is driven at a low speed so that the original document placing means rises at a low speed until the original bundle placed on the sheet is separated and conveyed by the separating and conveying means.

  With this configuration, the uppermost document in the document stack on the document placing unit can always be accurately placed at the proper feeding position.

  Further, in the automatic document feeder according to the present invention, the drive control unit drives the drive unit according to the distance between the position of the uppermost document in the document bundle and the movement target position of the document. It is characterized by changing.

  With this configuration, the driving unit is driven at a high speed when the distance to the movement target position is large, and the driving unit is driven at a low speed when the distance to the movement target position becomes small. The time from the setting to the start of the copying operation can be shortened, and the document placing means can be stopped accurately at an appropriate position to stably separate and convey the document.

  The automatic document feeder according to the present invention further includes document position detecting means for detecting the position of the uppermost document in the document bundle, and the drive control means detects the document bundle detected by the document position detecting means. The driving speed of the driving means is changed in accordance with the distance between the position of the uppermost original of the original bundle and the movement target position of the original obtained from the position of the uppermost original.

  With this configuration, the position of the uppermost document in the document bundle can always be detected by the document position detecting means, and the document placing means can be moved quickly and accurately.

  Further, in the automatic document feeder according to the present invention, the drive control unit is configured to perform the document loading according to a plurality of situations including the state of the document placing unit and the placement state of the document bundle on the document placing unit. The drive speed of the drive means is changed so that the time required for raising and lowering the placing means is minimized, and the document placing means is raised and lowered stably.

  With this configuration, the movable document table 3 can be moved quickly and accurately.

  Further, in the automatic document feeder according to the present invention, the driving means includes a motor, and the drive control means changes the speed of raising and lowering the document placing means by changing the rotation speed of the motor. It is characterized by letting.

  With this configuration, it is possible to easily change the moving speed of the document placing means.

  In the automatic document feeder according to the present invention, the driving unit includes a motor and a clutch connected to the motor, and the driving control unit disconnects the clutch from the motor, whereby the document placing unit. Is lowered by its own weight.

  With this configuration, the document placing unit can be quickly lowered, and the power consumed by the driving unit can be reduced.

  In the automatic document feeder according to the present invention, the driving unit includes a motor and a cam connected to the motor, and the driving control unit rotates the cam by the motor, whereby the document placing unit. It is characterized in that it is raised above a certain height and then lowered by its own weight.

  With this configuration, the document placing unit can be quickly lowered from the proper feeding position without changing the rotation direction of the driving unit, and the power consumed by the driving unit can be reduced.

  In the automatic document feeder according to the present invention, the driving means includes a motor having a rotating shaft arranged vertically and an inclination cam connected to the motor, and the drive control means causes the motor to move the inclination cam. By rotating, the document placing means is raised above a certain height and then lowered by its own weight.

  With this configuration, the document placing unit can be quickly lowered from the proper feeding position without changing the rotation direction of the driving unit, and the power consumed by the driving unit can be reduced.

  According to the present invention, it is possible to provide an automatic document feeder that can shorten the time from when a document is set on the document table to when the copy operation is started.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a configuration of an automatic document feeder according to an embodiment of the present invention.

  First, the configuration will be described.

  As shown in FIG. 1, the automatic document feeder 50 includes a document table 2 on which a document bundle 1 composed of a plurality of documents is placed with the document surface facing upward, and a document bundle 1 placed on the document table 2. A pickup roller 7 that transports the uppermost document, a paper feed belt 9 and a reverse roller 10 that separate the document transported by the pickup roller 7, and a single document that has been separated into a slit in the image forming apparatus main body 400. A pull-out roller 12, an intermediate roller 14, and a reading entrance roller 16 that conveys to the vicinity of the glass 21, a reading roller 19 that conveys the document conveyed to the vicinity of the slit glass 21 while making contact with the slit glass 21, A reading exit roller 23 that further conveys the document that has been read at the reading position 20, and a reading exit roller 23. Includes a discharge roller 28 for discharging the feed is a document, a paper discharge tray 29 ejected documents is placed.

  An image forming apparatus main body 400 is disposed below the automatic document feeder 50. The automatic document feeder 50 is attached to the image forming apparatus main body 400 so as to be freely opened and closed via an opening / closing mechanism (not shown). Yes. The image forming apparatus main body 400 includes a scanner unit (not shown) that reads a document transported by the automatic document transport device 50, a printer unit that prints on transfer paper, a paper feeding unit, and a control unit (not shown) that controls the operations of these units. Yes. The automatic document feeder 50 and the image forming apparatus main body 400 constitute an image forming apparatus 450.

  The document placed on the document table 2 passes through each part of the transport path before being discharged to the discharge tray 29. The conveyance path includes a document setting unit A on which the document bundle 1 is placed, a separation feeding unit B that separates and feeds one document from the placed document bundle 1, and a feeding document. A registration unit C that draws and conveys a document after alignment, a turn unit D that turns the conveyed document and conveys the document surface downward, and a surface of the document. A first reading and conveying unit E that reads from below the slit glass 21, a second reading and conveying unit F that reads the back side of the document, a paper discharge unit G that discharges the document whose front and back have been read to the outside, and And a stack portion H on which a document is placed. Note that the front side of the document refers to a surface that faces upward on the document table 2 and is read by the first reading / conveying unit E, and the back side of the document faces downward on the document table 2 and corresponds to the second reading / conveying unit F. The surface on which reading is performed.

  FIG. 2 is a block diagram showing the configuration of the control unit of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 2, the automatic document feeder 50 includes a controller 100 that controls the entire automatic document feeder 50. The automatic document feeder 50 also includes a registration sensor 17, a document set sensor 5, a paper discharge sensor 24, an abutment sensor 11, a document width sensor 13, a reading entrance sensor 15, a sensor for inputting a signal to the controller 100. The paper proper position sensor 8, the home position sensor 6, the bottom plate distance measuring sensor 303, and the weight detection sensor 301 are provided. The automatic document feeder 50 also includes a second reading unit 25, a pickup motor 101, a paper feed motor 102, a reading motor 103, a paper discharge motor 104, a bottom plate lift, and the like as an actuator that controls driving by outputting a signal from the controller 100. A motor 105 and an electromagnetic clutch 305 are provided.

  The image forming apparatus main body 400 includes a main body control unit 111 that controls the image forming apparatus main body 400 and a main body operation unit 108 that performs various input operations and operation instructions. The controller 100 and the main body control unit 111 are connected via the I / F 107, and data such as a control signal is exchanged between them.

  FIG. 3 is a block diagram showing the configuration of the second reading unit of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 3, the second reading unit 25 includes a light source unit 200 that irradiates light on a document based on a lighting signal from the controller 100, a plurality of sensor chips 201 that receive reflected light from the document, A plurality of amplifying units 202 that amplify signals output from the sensor chip 201, an A / D 203 that converts the amplified signals from analog signals to digital signals, and an image processing unit 204 that performs image processing on the digitally converted signals. A frame memory 205 that stores the image-processed signal, an output control circuit 206 that controls output of the signal stored in the frame memory 205 based on a timing signal from the controller 100, and a signal from the output control circuit 206 Is provided to the main body control unit 111. The second reading unit 25 is supplied with power from the controller 100.

  Here, the configuration of the automatic document feeder 50 will be described according to the order in which the document placed on the document table 2 is discharged to the discharge tray 29. First, a document bundle 1 composed of a plurality of documents is placed on a document table 2 including a movable document table 3 with the surface facing upward. Next, the position in the width direction of the document bundle 1, that is, the position in the direction orthogonal to the conveyance direction is positioned by a side guide (not shown). The placement of the document on the document table 2 is detected by the set filler 4 and the document set sensor 5, and a detection signal is output to the main body control unit 111 of the image forming apparatus main body 400 via the I / F 107. An outline of the length of the document in the conveyance direction is detected by document length detection sensors 30 and 31 provided on the surface of the document table 2. As the document length detection sensors 30 and 31, a reflection type sensor that detects without contact with the document by optical means or a contact type actuator that can detect even when there is only one document can be used. . The document length detection sensors 30 and 31 are arranged so that it can be determined whether the document is placed vertically or horizontally.

  The movable document table 3 is configured to move up and down in the directions of arrows a and b in FIG. When it is detected by the set filler 4 and the document set sensor 5 that the document is placed on the document table 2, the controller 100 rotates the bottom plate raising motor 105 in the normal direction so that the uppermost document in the document bundle 1. The movable document table 3 is lifted so that is in contact with the pickup roller 7. Hereinafter, the position where the uppermost document of the document bundle 1 contacts the pickup roller 7 is referred to as an appropriate feeding position.

  The pickup roller 7 is operated by the pickup motor 101 via the cam mechanism in the directions of arrows c and d in FIG. 1 and is pushed by the document on the raised movable document table 3 to be lifted in the direction of arrow c, so An upper limit of movement is detected by the position sensor 8. The proper paper feed position sensor 8 is a sensor for detecting that the movable original table 3 is raised and the uppermost original of the original bundle 1 is maintained at an appropriate height.

  When the set position of the original is detected by the set filler 4 and the original set sensor 5 while the home position sensor 6 detects that the movable original table 3 is in the lowered position, the controller 100 reads the original bundle. The bottom plate raising motor 105 is rotated at a high speed so that the uppermost part of 1 reaches the proper paper feed position, and the movable original table 3 is stabilized when the uppermost part of the original bundle 1 reaches the proper paper feed position. The rotation of the bottom plate raising motor 105 is decelerated to a predetermined speed so as to stop. That is, the controller 100 changes the driving speed of the bottom plate raising motor 105 in accordance with a change in the document stack placement state on the movable document table 3.

  FIG. 4 is a cross-sectional view showing the configuration of the movable document table of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 4, the movable document table 3 is provided with a weight detection sensor 301 that detects the weight of the document stacked on the movable document table 3. A detection signal from the weight detection sensor 301 is output to the controller 100. The controller 100 changes the rotational speed of the bottom plate raising motor 105 as shown in FIG. 5 based on the weight of the document detected by the weight detection sensor 301.

  FIG. 5 is a diagram showing a speed control curve of the bottom plate raising motor of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 5, when the weight of the document detected by the weight detection sensor 301 is equal to or greater than a predetermined threshold, the controller 100 causes the bottom plate raising motor 105 to move as indicated by the straight line A of the speed control curve. Is rotated at a low speed to raise the movable document table 3 at a low speed while maintaining a sufficiently stable driving force.

  On the other hand, when the weight of the document detected by the weight detection sensor 301 is less than a predetermined threshold, the controller 100 rotates the bottom plate raising motor 105 at a high speed as indicated by the straight line B of the speed control curve. As a result, the movable document table 3 is raised at a high speed so that the uppermost document in the document bundle 1 quickly reaches the appropriate feeding position.

  Further, as indicated by the straight line C of the speed control curve, the controller 100 may continuously change the rotation speed of the bottom plate raising motor 105 in accordance with the weight of the document detected by the weight detection sensor 301. In this case, the controller 100 controls the rotational speed of the bottom plate raising motor 105 so as to satisfy both securing a stable driving force and shortening the raising time of the movable document table 3.

  FIG. 6 is a cross-sectional view showing the configuration of the movable document table of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 6, by providing a weight detection sensor group 302 including a plurality of weight detection sensors 301 on the movable document table 3, the weight of the document on the movable document table 3 can be accurately detected. In this case, the controller 100 can more appropriately control the rotation speed of the bottom plate raising motor 105 based on accurate weight detection results obtained by the plurality of weight detection sensors 301. The plurality of weight detection sensors 301 are preferably arranged in both the document conveyance direction and the width direction.

  The controller 100 stops the raising of the movable document table 3 by stopping the bottom plate raising motor 105 when the appropriate feeding position sensor 8 is turned on. Further, the controller 100 rotates the bottom plate raising motor 105 to raise the movable document table 3 when the document upper surface position is lowered by feeding the document and the appropriate sheet feed position sensor 8 is turned off. The controller 100 repeats raising and stopping of the movable document table 3 based on on and off of the proper feeding position sensor 8 so that the uppermost original of the original bundle 1 always maintains the proper feeding position. It has become.

  Until the document set sensor 5 detects that the document stack 1 on the movable document table 3 has run out, the uppermost document in the document stack 1 is at the proper feeding position or slightly lowered. Either state. Therefore, the controller 100 rotates the bottom plate raising motor 105 at a low speed to raise the movable original table 3 at a low speed when the upper surface position of the original is lowered due to the feeding of the original and the appropriate paper feed position sensor 8 is turned off. It is like that.

  When the controller 100 detects that all the documents on the movable document table 3 have been fed and the document set sensor 5 has lost the document bundle 1 on the movable document table 3, the controller 100 reverses the bottom plate raising motor 105, The movable document table 3 is lowered to the home position so that the next document bundle can be set. At this time, the controller 100 quickly moves the movable document table 3 to the home position by rotating the bottom plate raising motor 105 at a high speed so that the next document bundle 1 can be quickly placed on the movable document table 3. It is designed to be lowered. That is, the controller 100 changes the driving speed of the bottom plate raising motor 105 in accordance with a change in the document stack placement state on the movable document table 3.

  After the main body operation unit 108 is operated to specify either the double-side mode or the single-side mode, the print key is pressed, and the main body control unit 111 outputs a document feed signal to the controller 100 via the I / F 107. Then, the controller 100 rotates the pickup roller 7 by rotating the paper feed motor 102 forward. The pickup roller 7 that has started rotating picks up the uppermost document on the document table 2 or several documents including the uppermost document.

  Note that the setting of the duplex mode or the simplex mode in the main body operation unit 108 may be the same for all documents placed on the document table 2 or may be different for each document. For example, the double-side mode can be designated for the first and tenth originals, and the single-side mode can be designated for the other originals among all ten originals.

  Next, when the paper feeding motor 9 is rotated forward by driving the paper feeding belt 9 and the reverse roller 10 clockwise, the paper feeding belt 9 guides the original in the paper feeding direction, and the reverse roller 10 sets the original in the paper feeding direction. Since the document is pushed out in the opposite direction, the uppermost document in the document stack 1 and the original document below the separated document are separated, and only the uppermost document is fed.

  Specifically, the reverse roller 10 is in contact with the paper feed belt 9 at a predetermined pressure, and in the state of being in direct contact with the paper feed belt 9 or in the state of being in contact with one original, the paper feed belt 9. 9 is rotated counterclockwise different from the original driving direction by the action of a torque limiter (not shown). Further, when two or more documents enter between the paper feed belt 9 and the reverse roller 10, the reverse roller 10 does not rotate with the paper feed belt 9, but rotates in the clockwise direction, which is the original driving direction. It works to push back excess documents and prevent double feeding.

  The document separated into one sheet by the action of the sheet feeding belt 9 and the reverse roller 10 is sent by the sheet feeding belt 9, then the leading edge is detected by the abutting sensor 11, and is further conveyed and stopped. Abuts on the roller 12. Next, when the original fed by a predetermined distance from the position detected by the abutting sensor 11 is pressed against the pull-out roller 12 with a predetermined amount of deflection, the paper feed motor 102 is stopped and the paper feed belt 9 is stopped. Drive stops. At this time, the pickup motor 101 is rotated to retract the pickup roller 7 from the upper surface of the document, and the document is fed only by the conveying force of the paper feed belt 9, whereby the leading edge of the document is sandwiched between the pull-out rollers 12 and Matching, so-called skew correction is performed. The pull-out roller 12 has a skew correction function, and is used for conveying the skew-corrected document after separation to the intermediate roller 14, and is driven by the reverse rotation of the paper feed motor 102. When the paper feed motor 102 rotates in the reverse direction, the pull-out roller 12 and the intermediate roller 14 are driven, but the pickup roller 7 and the paper feed belt 9 are not driven.

  The document width sensor 13 is composed of a plurality of photoelectric conversion elements such as a contact image sensor called CIS arranged in a direction perpendicular to the document transport direction, and is not shown in the figure disposed at the opposite portion of the transport path. The light reception level of the direct light emitted from the irradiation light source is output. The controller 100 detects a level difference between a portion shielded by the document and a portion not shielded by the light reception level of the document width sensor 13 when the document passes the position of the document width sensor 13, and the pull-out roller 12 The size of the conveyed document in the width direction is determined and notified to the main body control unit 111. The length of the document in the conveyance direction is detected from the motor pulse by reading the leading edge and the trailing edge of the document with the butting sensor 11. When the document is transported from the resist section C to the turn section D by driving the pull-out roller 12 and the intermediate roller 14, the transport speed at the resist section C is set higher than the transport speed at the first reading transport section E. Thus, the processing time for sending the document to the first reading conveyance unit E is shortened.

  When the leading edge of the document is detected by the reading entrance sensor 15, the document conveying speed is reduced to make the document conveying speed equal to the reading conveying speed before the leading edge of the document enters the reading inlet roller 16, and the reading motor 103 is driven forward to drive the reading inlet roller 16, the reading outlet roller 23, and the CIS outlet roller 27. When the leading edge of the document is detected by the registration sensor 17, the document conveyance speed is reduced over a predetermined conveyance distance, the document is temporarily stopped (registration stop) before the reading position 20, and via the I / F 107. Then, a registration stop signal is output to the main body control unit 111. When a reading start signal is received from the main body control unit 111, the original document that has been stopped is accelerated and conveyed so as to rise to a predetermined conveying speed before the leading edge reaches the reading position 20. At the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the reading position 20, a gate signal indicating an effective image area in the sub-scanning direction on the surface is output to the main body control unit 111. Note that the gate signal is continuously output until the trailing edge of the document passes through the first reading conveyance unit E.

  When the operation mode is the single-sided mode, the document that has passed through the first reading and conveying unit E is conveyed to the paper discharge unit G through the second reading unit 25. At this time, when the leading edge of the document is detected by the paper discharge sensor 24, the paper discharge roller 104 is rotated counterclockwise by the normal rotation drive of the paper discharge motor 104. Further, the drive speed of the discharge motor 104 is reduced immediately before the trailing edge of the document comes out of the nip area of the discharge roller 28 by the pulse count of the discharge motor 104 after the discharge sensor 24 detects the leading edge of the document. By doing so, the document discharged onto the discharge tray 29 is prevented from jumping out.

  When the operation mode is the duplex mode, the second timing is reached when the leading edge of the document reaches the second reading unit 25 based on the pulse count of the reading motor 103 after the leading edge of the document is detected by the paper discharge sensor 24. A gate signal indicating an effective image area in the sub-scanning direction is output from the controller 100 to the reading unit 25. The gate signal is continuously output from the second reading unit 25 until the trailing edge of the original comes out. The surface of the second reading unit 25 is subjected to an antifouling coating process in order to prevent transfer of foreign matters on the glue attached to the document. The second reading roller 26 serves as a reference white part for obtaining shading data in the second reading unit 25 as well as suppressing floating of the original in the second reading unit 25.

  7 and 8 are cross-sectional views showing the configuration of the bottom plate distance measuring sensor of the movable document table of the automatic document feeder according to the embodiment of the present invention, and an example of the output characteristics of the bottom plate distance measuring sensor.

  As shown in FIG. 7, the automatic document feeder 50 may include a bottom plate distance measuring sensor 303 instead of the home position sensor 6, and the bottom plate distance measuring sensor 303 may detect the position of the movable document table 3. The bottom plate distance measuring sensor 303 is disposed above the movable document table 3 and measures the distance to the uppermost document of the document bundle 1 placed on the movable document table 3. In this case, the home position sensor 6 only detects that the movable document table 3 is in the lowered position, whereas the home position sensor 6 detects the topmost document of the document stack 1 placed on the movable document table 3. The distance can always be measured. Further, the homing operation for moving the control object to the reference position, which is indispensable when a single sensor such as the home position sensor 6 is used, becomes unnecessary, and the useless operation of the movable document table 3 can be omitted.

  As shown in FIG. 8, the output characteristic of the bottom plate distance measuring sensor 303 is such that, for example, the output voltage increases linearly as the measurement distance increases. When the output voltage from the bottom plate distance measuring sensor 303 is input to the controller 100, the controller 100 determines whether the document bundle 1 placed on the movable document table 3 from the bottom plate distance measuring sensor 303 depends on the magnitude of the received output voltage. The distance to the uppermost document is calculated, and optimal control is performed based on the distance from the control target position such as the appropriate feeding position or the standby position of the movable document table 3 to the actual position of the movable document table 3. It has become. Further, the controller 100 refers to the detection result of the weight detection sensor 301 in addition to the output from the bottom plate distance measuring sensor 303 so that the movable document table 3 is raised and lowered at an optimum speed. The maximum rotation speed of 105 may be limited.

  FIG. 9 is a cross-sectional view showing the configuration of the movable document table of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 9, an electromagnetic clutch 305 is provided in a portion that transmits the drive of the bottom plate raising motor 105 to the bottom plate raising lever 304, and the electromagnetic clutch 305 is turned off when the movable document table 3 is lowered to the lowest reference position. Thus, the movable document table 3 can be quickly lowered by its own weight without rotating the bottom plate raising motor 105 at a high speed.

  FIGS. 10A to 10C are cross-sectional views showing the raising and lowering operations of the movable document table of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIGS. 10A to 10C, an eccentric cam 306 is provided on the main shaft of the bottom plate raising motor 105, and the bottom surface of the movable document table 3 is supported by the eccentric cam 306. May be raised and lowered. In this case, when the movable document table 3 is raised from the lowest position to the proper feeding position, the movable document table 3 is rotated by rotating the eccentric cam 306 so that the movable document table 3 is shown in FIG. 10 (A), FIG. It is made to raise in order of 10 (C). Further, when the movable document table 3 is lowered from the appropriate feeding position to the lowest position, the eccentric cam 306 is further rotated to move the movable document to a position higher than a predetermined position as shown in FIG. After the table 3 is lifted, the eccentric cam 306 is further rotated clockwise so that the movable document table 3 is quickly lowered by its own weight, and the movable document table 3 is moved to the lowest position as shown in FIG. To move to.

  FIGS. 11A to 11C are cross-sectional views showing the raising and lowering operations of the movable document table of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIGS. 11A to 11C, instead of the eccentric cam 306, a spiral member 307 having a slope cam function and a contact member 308 that moves up and down by the spiral member 307 are used. The movable document table 3 may be raised to a position higher than a predetermined position via the contact member 308 by rotating the shaped member 307. In this case, by further rotating the spiral member 307 from the state shown in FIG. 11C, the state shown in FIG. 11A is obtained, and the movable document table 3 can be quickly lowered by its own weight.

  Next, the operation will be described.

  FIG. 12 is a flowchart showing the calculation operation of the speed control curve of the movable document table of the automatic document feeder according to the embodiment of the present invention. FIGS. 13 to 15 are diagrams showing an example of a speed control curve of the bottom plate raising motor of the automatic document feeder according to the embodiment of the present invention.

  As shown in FIG. 12, first, the controller 100 detects the weight of the document bundle 1 placed on the movable document table 3 by the weight detection sensor 301 (step S1), and the movable document table 3 is raised and lowered. The maximum rotation speed of the bottom plate raising motor 105 that maximizes the speed, the acceleration curve from the stop state to the maximum rotation speed, and the deceleration curve from the maximum rotation speed to the stop state are determined (step S2). These maximum rotation speed, acceleration curve, and deceleration curve can be changed depending on the actual apparatus configuration, ascending control or descending control, and are as shown in FIG.

  Next, in the acceleration curve and the deceleration curve determined in step S2, the controller 100 determines the advance amount (La) until the maximum rotational speed is reached from the current rotational speed shown in FIG. 14 and the stop speed from the maximum speed. The amount of advance (Lb), the total (La + Lb + Lc) of the constant speed rotation distance (Lc) necessary for performing stable ascent and descent control, and the uppermost part of the document bundle 1 on the movable document table 3 to be controlled The distance (Ld) between the current position of the original and the control target position is compared (step S3).

  Next, if La + Lb + Lc> Ld in step S3, the controller 100 gradually decreases the maximum rotation speed while gradually decreasing the maximum rotation speed, acceleration curve, and deceleration curve of the bottom plate raising motor 105 until La + Lb + Lc> Ld is not satisfied. Are respectively corrected (step S4).

  On the other hand, if La + Lb + Lc ≦ Ld in step S3, the controller 100 obtains the actual low-speed rotation distance Lc ′ by Lc ′ = Ld− (La + Lb), and a speed control curve as shown in FIG. Is calculated (step S5). Alternatively, even when the speed control curve is calculated according to steps S1 to S5 and the rotation of the bottom plate raising motor 105 is controlled, when the appropriate paper feed position sensor 8 is turned on during the actual control processing. The controller 100 invalidates the current speed control curve and performs rapid deceleration processing. Further, after calculating the speed control curve according to steps S1 to S5 and controlling the rotation of the bottom plate raising motor 105, the proper sheet feeding position sensor 8 is not turned on when the bottom plate raising motor 105 is stopped. In this case, the controller 100 rotates the bottom plate raising motor 105 at a predetermined lowest rotational speed until the proper paper feed position sensor 8 is turned on. By doing so, it is possible to compensate for deviations caused by various disturbances that occur during the control of the bottom plate raising motor 105, and it is possible to control the movable document table 3 to be raised to the appropriate feeding position.

  In applying the present invention, the configuration of the automatic document feeder 50 described above may be partially applied in accordance with the constraints caused by the actual apparatus configuration, and the calculation procedure of the speed control curve is also applied to the present invention. Changes can be made without departing from the scope of the above. For example, in the case of executing simple control in which only one home position sensor 6 is provided and only two points of the home position and the appropriate paper feed position are set as control target positions, the distance between the current position and the control target position When changing the speed control curve according to (moving distance), the standard original stacking height is added to the moving distance when the current position is the home position and the control target position is the appropriate paper feed position. The calculated value may be “distance between the current position and the target position”, and this “distance between the current position and the target position” may always be applied as the movement distance.

  Further, in the case of a configuration that does not have means for detecting the weight of the document bundle 1 placed on the movable document table 3, when the document set is detected by the set filler 4 and the document set sensor 5, The predetermined predetermined weight value is regarded as the weight at the time of setting the original, and Steps S1 to S5 are executed. Even when the setting of the original is not detected because all the originals have been fed, the predetermined predetermined value is set. Can be regarded as the weight when the document is not set, and Steps S1 to S5 can be executed.

  As described above, the automatic document feeder according to the present embodiment includes the movable document table 3 on which the document bundle 1 composed of a plurality of documents is placed, and the uppermost part from the document bundle 1 placed on the movable document table 3. A pickup roller 7 that separates and conveys the original, and a bottom plate raising motor 105 that raises and lowers the movable original table 3 so that the uppermost original of the original bundle 1 contacts and separates from the pickup roller 7. In the automatic document feeder, the movable document table 3 is raised and lowered while changing the driving speed of the bottom plate raising motor 105 so that the uppermost document of the document bundle 1 contacts the pickup roller 7 with a predetermined pressure. Since the controller 100 is provided, the bottom plate raising motor 105 is rotated at a high speed so that the movable document table 3 can be rapidly raised, and is also possible. The copy operation is performed after the original is set on the movable original table 3 by rotating the bottom plate raising motor 105 at a low speed before the movable original table 3 stops so that the original table 3 finishes rising at an appropriate position. The time until the start can be shortened. Further, since the movable document table 3 finishes rising at an appropriate position, stable document separation and conveyance can be performed.

  Further, the automatic document feeder according to the present embodiment is configured such that the controller 100 changes the driving speed of the bottom plate raising motor 105 in accordance with the change in the placement state of the document bundle 1 on the movable document table 3. Therefore, by rotating the bottom plate raising motor 105 at a high speed or a low speed according to the presence or absence of the document bundle 1 on the movable document table 3, the copy operation is started after the document is set on the movable document table 3. The time can be shortened.

  Further, in the automatic document feeder according to the present embodiment, the controller 100 causes the movable document table 3 to be in the raised position, and all the document bundles 1 placed on the movable document table 3 are separated and conveyed by the pickup roller 7. In this case, since the bottom plate raising motor 105 is driven at a high speed so that the movable document table 3 is rapidly lowered, the time until the movable document table 3 is lowered and a new document bundle 1 is placed. Can be shortened.

  Further, in the automatic document feeder according to the present embodiment, when the controller 100 has the movable document table 3 in the lowered position and the document stack 1 is placed on the movable document table 3, the movable document table 3 is rapidly moved. Since the bottom plate raising motor 105 is driven at a high speed so as to rise, the time from when the original is set on the movable original table 3 to when the copy operation is started can be shortened.

  The automatic document feeder according to the present embodiment includes a weight detection sensor 301 that detects the weight of the document bundle 1 placed on the movable document table 3, and the controller 100 detects the weight detected by the weight detection sensor 301. Accordingly, the driving speed of the bottom plate raising motor 105 is changed, so that the movable document table 3 is moved at an appropriate speed according to the weight of the document bundle 1 placed on the movable document table 3. Can do.

  Further, the automatic document feeder according to the present embodiment is configured so that the controller 100 drives the bottom plate raising motor 105 at a low speed when the weight detected by the weight detection sensor 301 is equal to or greater than the threshold value. When the document stack 1 placed on the movable document table 3 is heavy, the movable document table 3 can be raised while maintaining a sufficient driving force at a low speed.

  In the automatic document feeder according to the present embodiment, the controller 100 is configured to drive the bottom plate raising motor 301 at a high speed when the weight detected by the weight detection sensor 301 is less than the threshold. When the document stack 1 placed on the movable document table 3 is light, the time from when the movable document table 3 is raised at a high speed in a short time and the document is set on the movable document table 3 until the copy operation is started is set. Can be shortened.

  Further, in the automatic document feeder according to the present embodiment, since the movable document table 3 includes at least one weight detection sensor 301, the automatic document feeder 3 corresponds to the weight of the document bundle 1 placed on the movable document table 3. The movement of the movable document table 3 can be controlled.

  Further, in the automatic document feeder according to the present embodiment, the controller 100 temporarily places the uppermost document of the document bundle 1 on the pickup roller 7 with a predetermined pressure and then places the document on the movable document table 3. The bottom plate raising motor 105 is driven at a low speed so that the movable document table 3 is raised at a low speed until the placed document bundle 1 is completely separated and conveyed by the pickup roller 7. The uppermost original of the original bundle 1 on the table 3 can always be accurately placed at the proper feeding position.

  Further, in the automatic document feeder according to the present embodiment, the controller 100 drives the driving speed of the bottom plate raising motor 105 according to the distance between the position of the uppermost document of the document bundle 1 and the movement target position of the document. The bottom plate raising motor 105 is driven at a high speed when the distance to the movement target position is large, and the bottom plate raising motor 105 is driven at a low speed when the distance to the movement target position becomes small. As a result, it is possible to shorten the time from when the document is set on the movable document table 3 to when the copy operation is started, and to stably stop the movable document table 3 at an appropriate position and stably separate and transport the document. It can be performed.

  Further, since the automatic document feeder according to the present embodiment includes the bottom plate distance measuring sensor 303 that detects the position of the uppermost document in the document bundle 1, the bottom plate distance measuring sensor 303 always uses the bottom plate distance measuring sensor 303. The position of the original can be detected, and the movable original table 3 can be moved quickly and accurately.

  Further, in the automatic document feeder according to the present embodiment, the controller 100 has the movable document table 3 in accordance with a plurality of situations including the situation of the movable document table 3 and the placement status of the document bundle 1 on the movable document table 3. Since the drive speed of the bottom plate raising motor 105 is changed so that the time required for raising and lowering is minimized, and the movable document table 3 is stably raised and lowered, the movable document table 3 can be moved quickly. Accurate movement can be performed.

  In the automatic document feeder according to the present embodiment, the controller 100 is configured to change the ascent and descent speeds of the movable document table 3 by changing the rotation speed of the bottom plate raising motor 105. The moving speed of the movable document table 3 can be easily changed.

  In the automatic document feeder according to the present embodiment, the controller 100 disconnects the electromagnetic clutch 305 from the bottom plate raising motor 105 so that the movable document table 3 is lowered by its own weight. 3 can be quickly lowered, and the power consumed by the bottom plate raising motor 105 can be reduced.

  Further, in the automatic document feeder according to the present embodiment, the controller 100 rotates the eccentric cam 306 by the bottom plate raising motor 105, so that the movable document table 3 rises above a certain height and then descends by its own weight. Thus, the movable document table 3 can be quickly lowered from the appropriate feeding position without changing the rotation direction of the bottom plate raising motor 105, and the power consumed by the bottom plate raising motor 105 is reduced. Can be made.

  In the automatic document feeder according to the present embodiment, the controller 100 causes the bottom plate raising motor 105 to rotate the spiral member 307 as an inclined cam, so that the movable document table 3 rises to a certain height or more. Therefore, the movable document table 3 can be quickly lowered from the proper feeding position without changing the rotation direction of the bottom plate raising motor 105, and the bottom plate raising motor 105 can be lowered. Power consumption can be reduced.

  As described above, the automatic document feeder according to the present invention has the effect of shortening the time from when a document is set on the document table to when the copy operation is started. This is useful as an automatic document feeder that separates and conveys the uppermost document of the bundle of documents.

1 is a cross-sectional view showing a configuration of an automatic document feeder according to an embodiment of the present invention. FIG. 3 is a block diagram illustrating a configuration of a control unit of the automatic document feeder according to the embodiment of the present invention. It is a block diagram which shows the structure of the 2nd reading part of the automatic document feeder which concerns on embodiment of this invention. FIG. 3 is a cross-sectional view showing a configuration of a movable document table of the automatic document feeder according to the embodiment of the present invention. It is a figure which shows the speed control curve of the baseplate raising motor of the automatic document feeder which concerns on embodiment of this invention. FIG. 3 is a cross-sectional view showing a configuration of a movable document table of the automatic document feeder according to the embodiment of the present invention. It is sectional drawing which shows the structure of the baseplate ranging sensor of the movable original table of the automatic original conveying apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the output characteristic of the baseplate ranging sensor of the automatic document feeder which concerns on embodiment of this invention. FIG. 3 is a cross-sectional view showing a configuration of a movable document table of the automatic document feeder according to the embodiment of the present invention. (A)-(C) are sectional drawings which show the raising and lowering operations of the movable document table of the automatic document feeder according to the embodiment of the present invention. (A)-(C) are sectional drawings which show the raising and lowering operations of the movable document table of the automatic document feeder according to the embodiment of the present invention. FIG. 5 is a flowchart showing a calculation operation of a speed control curve of a movable document table of the automatic document feeder according to the embodiment of the present invention. It is a figure which shows an example of the speed control curve of the baseplate raising motor of the automatic document feeder which concerns on embodiment of this invention. It is a figure which shows an example of the speed control curve of the baseplate raising motor of the automatic document feeder which concerns on embodiment of this invention. It is a figure which shows an example of the speed control curve of the baseplate raising motor of the automatic document feeder which concerns on embodiment of this invention.

Explanation of symbols

1 Document bundle 2 Document table 3 Movable document table (document placement means)
4 Set filler 5 Document set sensor 6 Home position sensor 7 Pickup roller (separation transport means)
DESCRIPTION OF SYMBOLS 8 Feed appropriate position sensor 9 Paper feed belt 10 Reverse roller 11 Abutting sensor 12 Pull-out roller 13 Document width sensor 14 Intermediate roller 15 Reading entrance sensor 16 Reading entrance roller 17 Registration sensor 19 Reading roller 20 Reading position 21 Slit glass 23 Reading exit Roller 24 Paper discharge sensor 25 Second reading section 26 Second reading roller 27 CIS exit roller 28 Paper discharge roller 29 Paper discharge tray 30, 31 Document length detection sensor 100 Controller (drive control means)
DESCRIPTION OF SYMBOLS 101 Pickup motor 102 Paper feed motor 103 Reading motor 104 Paper discharge motor 105 Bottom plate raising motor (drive means, motor)
107 I / F
108 Main unit operation unit 111 Main unit control unit 301 Weight detection sensor (weight detection means)
302 Weight detection sensor group 303 Bottom plate distance sensor 304 Bottom plate raising lever 305 Electromagnetic clutch (clutch)
306 Eccentric cam (cam)
307 Spiral member (tilt cam)
308 Contact member 400 Image forming apparatus main body 450 Image forming apparatus

Claims (16)

Document placing means for placing a bundle of documents composed of a plurality of documents;
Separating and conveying means for separating and conveying the uppermost original of the original bundle from the original bundle placed on the original placing means;
In an automatic document conveying apparatus comprising a driving unit that raises and lowers the document placing unit so that the uppermost document of the document bundle contacts and separates from the separating and conveying unit,
Drive control means for raising and lowering the document placement means while changing the drive speed of the drive means so that the uppermost document in the document bundle contacts the separation conveying means at a predetermined pressure. An automatic document feeder characterized by that.   2. The automatic document feeder according to claim 1, wherein the drive control unit changes the drive speed of the drive unit in accordance with a change in the placement state of the document bundle in the document placement unit.   When the document placement means is in the raised position and all the bundles of documents placed on the document placement means are separated and transported by the separation transport means, the drive control means 3. The automatic document feeder according to claim 2, wherein the driving unit is driven at a high speed so as to rapidly descend.   When the document placing means is at the lowered position and the document stack is placed on the document placing means, the drive control means moves the drive means at a high speed so that the document placing means rises rapidly. The automatic document feeder according to claim 2, wherein the automatic document feeder is driven by. A weight detecting means for detecting the weight of the document bundle placed on the document placing means;
2. The automatic document feeder according to claim 1, wherein the driving control unit changes a driving speed of the driving unit according to the weight detected by the weight detecting unit.   6. The automatic document feeder according to claim 5, wherein the drive control unit drives the drive unit at a low speed when the weight detected by the weight detection unit is equal to or greater than a threshold value.   7. The automatic document feeder according to claim 5, wherein the drive control unit drives the drive unit at a high speed when the weight detected by the weight detection unit is less than a threshold value. .   8. The automatic document feeder according to claim 5, wherein the document placement unit includes at least one weight detection unit.   After the drive control means once makes contact with the uppermost original of the original bundle at a predetermined pressure with respect to the separating and conveying means, the original bundle placed on the original placing means becomes the separating and conveying means. 2. The automatic document feeder according to claim 1, wherein the driving unit is driven at a low speed so that the document placing unit rises at a low speed until all of the documents are separated and transported.   The drive control means changes the drive speed of the drive means according to the distance between the position of the uppermost original of the original bundle and the movement target position of the original. The automatic document feeder described. An original position detecting means for detecting the position of the uppermost original of the original bundle;
The drive control means sets the distance between the position of the uppermost original of the original bundle and the target movement position of the original obtained from the position of the uppermost original of the original bundle detected by the original position detecting means. 11. The automatic document feeder according to claim 10, wherein the driving speed of the driving unit is changed accordingly.   The drive control means minimizes the time required for raising and lowering the original placing means according to a plurality of situations including the situation of the original placing means and the placement situation of the original bundle on the original placing means. 12. The automatic according to claim 1, wherein a driving speed of the driving unit is changed so that the document placing unit is stably raised and lowered. Document transport device. The drive means comprises a motor;
12. The apparatus according to claim 1, wherein the drive control means changes the ascent and descent speed of the document placing means by changing the rotational speed of the motor. The automatic document feeder described in 1. The drive means comprises a motor and a clutch connected to the motor;
12. The automatic according to claim 1, wherein the drive control means lowers the document placing means by its own weight by disconnecting the clutch from the motor. Document transport device. The drive means comprises a motor and a cam connected to the motor;
12. The drive control unit according to claim 1, wherein the drive control unit rotates the cam by the motor to raise the document placing unit to a certain height or higher and then lowers the original document by its own weight. The automatic document feeder according to any one of claims. The drive means comprises a motor having a rotation axis arranged vertically and an inclined cam connected to the motor;
12. The drive control unit according to claim 1, wherein the document placing unit is raised above a certain height by rotating the tilt cam by the motor and then lowered by its own weight. The automatic document feeder according to claim 1.

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