JP2011057386A - Automatic document feeding device, image reading device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an automatic document feeding device which improves productivity by quickening a timing for feeding the next document. <P>SOLUTION: In accordance with the detecting output of a document face detecting means 8 provided near a pickup roller 7, the movement of a movable document table is controlled to keep the upper face positions of a bunch of documents P consistently at almost the same position. The pickup roller 7 has a cut portion 7b, and is stopped with the cut portion 7b directed to the documents, when stopped. This eliminates the need for moving the pickup roller 7 up and down to quicken the timing for feeding the next document. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an automatic document feeder that is mounted on an image reading apparatus and conveys a document.

  An image reading apparatus for reading a document image is well known and widely used as an image reading unit provided in a scanner or an image forming apparatus. An automatic document feeder (ADF) that is mounted on the image reading apparatus and conveys a document to a reading position is also well known.

In the automatic document feeder, the document set on the document stacking unit is called by the pickup roller, and separated and conveyed by the separation mechanism unit.
A general automatic document feeder is configured to feed in order from the upper surface of a bundle of documents stacked on a document stacking unit, and a pickup roller is attached above the document stacking unit. As a general operation of the pick-up roller, the document is lowered once from the upper retracted position and rotated after contact with the document to convey the document to the separation mechanism, and the document to the separation mechanism and the drawing roller downstream of the separation mechanism. A system is used in which the pickup roller rises when the tip is conveyed.

  For example, Japanese Patent Laid-Open No. 2007-254146 (Patent Document 1) includes a pickup roller that is supported by a swinging pickup arm so as to be rotatable and movable up and down. An automatic document feeder configured to sequentially feed into a conveyance path is disclosed.

  By the way, when the productivity of the machine (the number of sheets that can be read per minute in the reading device) increases, it is necessary to shorten the sheet interval (the interval between the trailing edge of the first document and the leading edge of the next document). It is necessary to advance the paper feed timing.

  However, in the conventional mechanism for moving up and down the pickup roller, the pickup roller is lowered and temporarily moved down to advance the feeding timing of the next document in order to carry the document. There was a problem of becoming a big bottleneck. The one described in Patent Document 1 prevents non-feeding and separation failure due to a difference in the paper thickness of the document, but the problem of improving productivity cannot be solved.

  The present invention solves the above-described problems in a conventional automatic document feeder, and can improve the productivity by advancing the feeding timing of the next document, and an image reading apparatus and an image forming apparatus provided with the automatic document feeder. It is an issue to provide.

  According to the present invention, there is provided an automatic document feeder having a document stacking unit for setting a document and a pickup roller for calling and transporting the document set on the document stacking unit. It has at least one cut part with a part cut, is rotationally driven by a driving means in a fixed arrangement, and is controlled to stop the cut part toward the original surface when stopped, and the original The stacking means is provided so as to be movable so as to approach and separate from the pickup roller, and provided in the vicinity of the pickup roller is a document surface detection means for detecting the upper surface position of the document stacked on the document stacking means, Based on the detection output of the original surface detecting means, the pickup roller on the upper surface of the original set on the original stacking means That position is always resolved by being configured to maintain approximately the same position.

  Preferably, the document surface detecting means detects the document surface when the upper surface of the document set on the document stacking means approaches the inside of the roller outer peripheral extension line in the cut portion of the pickup roller.

The document surface detecting means preferably includes a filler member that is swingably or slidable and contacts the document surface, and a sensor that detects the filler member.
Preferably, the document surface detection means includes a non-contact type sensor that detects the document surface in a non-contact manner and at least one document pressing member that is disposed in the vicinity of the non-contact type sensor and presses the document.

In the pickup roller, it is preferable that a connection portion between the cut portion and the arc portion is configured to have a curved shape.
Further, it is preferable that a plurality of the pickup rollers are provided and controlled so that the drive timing of each pickup roller is shifted.

Further, according to the present invention, the above problem is solved by an image reading apparatus provided with the automatic document feeder according to any one of claims 1 to 6.
According to the present invention, the above problem is solved by an image forming apparatus including the automatic document feeder according to any one of claims 1 to 6 or the image reading device according to claim 7.

  According to the automatic document feeder, the image reading apparatus, and the image forming apparatus of the present invention, it is not necessary to move the pickup roller up and down (up and down), the timing of feeding the next document can be advanced, and the productivity is improved. Can be made.

  According to the configuration of the second aspect, the document can be reliably sent out when the pickup roller is rotated, and the non-feed of the document can be prevented. That is, it is possible to prevent the state where the pickup roller and the document do not contact with each other due to the error of the detection means.

According to the configuration of the third aspect, the document surface detection means can be configured with a simple configuration and at a low cost.
According to the configuration of the fourth aspect, it is possible to prevent erroneous detection due to the curling of the document and to accurately detect the upper surface of the document.

According to the fifth aspect of the present invention, it is possible to eliminate the catch at the time of rotating the pickup roller, smooth the roller rotation, and suppress the chipping and wear of the roller.
According to the configuration of the sixth aspect, since at least one pickup roller is in contact with the document while the document is being conveyed, it is possible to perform reliable conveyance and to convey a long distance even when the roller diameter of the pickup roller is small.

1 is a cross-sectional view illustrating a configuration of a sheet-through ADF that is an example of an automatic document feeder according to the present invention. It is a block diagram showing a control system of the automatic document feeder. It is a block diagram which shows the structure of the 2nd image reading means for reading a back surface original. FIG. 10 is a detailed view showing a document pickup section in a conventional automatic document feeder. FIG. 3 is an enlarged view showing a document pickup unit in the embodiment of the present invention. It is a figure for demonstrating a structure and operation | movement of a document surface detection means. It is a figure which shows another example of a document surface detection means. It is sectional drawing which shows the shape of a pick-up roller. 2 shows a configuration example in which a plurality of pickup rollers are provided. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus including a document stop type image reading apparatus and an automatic document feeder. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The present invention is an automatic document feeder (ADF) that conveys a document to a reading unit of an image reading device such as an image reading unit or a scanner in an image forming apparatus such as a copying machine or a facsimile, or a recording medium inside the copying machine. The present invention relates to a mechanism for transporting a sheet such as a document or a sheet, such as a sheet feeding unit that transports a sheet from a sheet stacking unit to a copying machine. In the present embodiment, as a representative example, the present invention will be described by taking up the case of conveying a document of a sheet through ADF mounted on a copying machine.

  FIG. 1 is a cross-sectional view showing the configuration of a sheet-through ADF that is an example of an automatic document feeder according to the present invention. FIG. 2 is a block diagram showing a control system of the automatic document feeder. FIG. 3 is a block diagram showing the configuration of the second image reading means 25 for reading the back side document. First, the basic configuration and operation of this embodiment will be described with reference to these drawings.

  The sheet-through ADF 1 according to this embodiment includes a document setting unit A for setting a read document bundle, a separation feeding unit B for separating and feeding documents one by one from the set document bundle, and a fed document. , And a turn part D that turns the conveyed original and conveys the original surface toward the reading side (downward). A first reading / conveying unit E for reading the front image of the original document from below the contact glass, a second reading / conveying unit F for reading the back side image of the original after reading, and discharging the original on which the front and back sides have been read out of the apparatus. A paper discharge unit G that performs stacking and holding a document after reading, a drive unit 101 to 105 that drives the transport operation, and a controller unit 100 that controls a series of operations. .

  The original bundle P to be read is set on the original table 2 including the movable original table 3. In this example, the document surface is set face up. The document table 2 is provided with a side guide (not shown), and the width direction of the document bundle P is positioned by the side guide in a direction orthogonal to the transport direction. The document set is detected by the set filler 4 and the set sensor 5 and transmitted to the main body control unit 111 by the I / F 107. Further, the length of the document in the conveyance direction is roughly determined by a document length detection sensor 30 or 31 (a reflective sensor or an actuator type sensor that can detect even one document) provided on the document table surface. Is determined (a sensor arrangement capable of determining at least whether the document size is vertical or horizontal is necessary).

  The movable document table 3 can be moved up and down in the directions a and b shown in FIG. 1 by a bottom plate raising motor 105. When the set filler 4 and the set sensor 5 detect that a document has been set, the bottom plate rises. The motor 105 is rotated forward to raise the movable document table 3 so that the uppermost surface of the document bundle P contacts the pickup roller 7. In the vicinity of the pickup roller 7, document surface detection means 8 (FIG. 5) described later is provided. Further, the pickup roller 7 has a cut portion 7b (FIG. 8) described later.

  When the enter key is pressed from the main body operation unit 108 and a document feed signal is transmitted from the main body control unit 111 to the controller unit 100 via the I / F 107, the pick-up roller 7 rolls by the forward rotation of the paper feed motor 102. Rotation is driven to pick up several (ideally one) originals on the original table 2. The rotation direction is a direction in which the uppermost document is conveyed to the sheet feeding port.

  The paper feed belt 9 is driven in the paper feed direction by the normal rotation of the paper feed motor 102, and the reverse roller 10 is driven to rotate in the reverse direction to the paper feed by the normal rotation of the paper feed motor 102. The document is separated, and only the uppermost document can be fed. More specifically, the reverse roller 10 is in contact with the paper feeding belt 9 at a predetermined pressure, and is rotated by the paper feeding belt 9 when in contact with the paper feeding belt 9 directly or through a document. When the document enters between the paper feeding belt 9 and the reverse roller 10 in the unlikely event that the original is in the counterclockwise direction, the revolving force is set to be lower than the torque of the torque limiter. 10 rotates in the clockwise direction, which is the original driving direction, and pushes back an extra original, thereby preventing double feeding.

  The original separated by the action of the paper feeding belt 9 and the reverse roller 10 is further fed by the paper feeding belt 9, and the leading edge is detected by the abutting sensor 11 and further abuts against the pull-out roller 12 stopped. Thereafter, the sheet feeding motor 102 is stopped in a state where it is fed a predetermined amount from the detection of the abutting sensor 11 and as a result is pressed against the pull-out roller 12 with a predetermined amount of bending. By doing so, the driving of the paper feed belt 9 is stopped. At this time, the cut portion 7b of the pickup roller 7 is stopped downward so that the original is fed only by the conveying force of the paper feeding belt 9, so that the leading edge of the original is in the nip of the upper and lower rollers of the pull-out roller 12. Enter and align the tip (skew correction).

  The pull-out roller 12 has the skew correction function and is a roller 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. At this time (at the time of reverse rotation of the paper feed motor 102), 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.

  A plurality of document width sensors 13 are arranged in the depth direction and detect the size in the width direction perpendicular to the conveyance direction of the document conveyed by the pull-out roller 12. Further, the length of the document in the conveying 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 to be higher than the transport speed at the reading transport section E. The processing time for sending the document to the reading unit is shortened.

  When the leading edge of the document is detected by the reading entrance sensor 15, before the leading edge of the document enters the nip of the upper and lower roller pairs of the reading entrance roller 16, deceleration is started in order to make the document transportation speed the same as the scanning transportation speed. At the same time, 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 registration sensor 17 detects the leading edge of the document, the registration sensor 17 decelerates over a predetermined conveyance distance, temporarily stops before the reading position 20, and transmits a registration stop signal to the main body control unit 111 via the I / F 107. . Subsequently, when a reading start signal is received from the main body control unit 111, the document whose registration has been stopped is accelerated and conveyed so as to rise to a predetermined conveying speed until the leading edge of the document reaches the reading position. At the timing when the leading edge of the document detected by the pulse count of the reading motor 103 reaches the reading unit, a gate signal indicating an effective image area in the sub-scanning direction on the first surface is sent to the main body control unit 111 and the first reading unit is set to the document. Sent until the trailing edge is removed.

  In the case of single-sided document reading, the document that has passed through the reading conveyance unit E is conveyed to the paper discharge unit G through the second reading unit F. At this time, when the leading edge of the original is detected by the paper discharge sensor 24, the paper discharge motor 104 is driven to rotate forward to rotate the paper discharge roller 28 counterclockwise. Further, the discharge motor driving speed is reduced immediately before the trailing edge of the document exits the nip between the upper and lower roller pairs of the discharge roller 28 by the pulse count of the discharge motor 104 from the detection of the leading edge of the document by the discharge sensor 24. Control is performed so that the document discharged onto the discharge tray 29 does not jump out.

  In the case of double-sided document reading, the second image reading unit 25 is detected at the timing when the document leading end reaches the second image reading unit 25 by the pulse count of the reading motor 103 after the discharge sensor 24 detects the document leading end. Then, a gate signal indicating an effective image area in the sub-scanning direction is transmitted from the controller unit 100 until the trailing edge of the document passes through the reading unit. The second reading roller 26 serves as a reference white part for obtaining shading data in the second reading unit as well as suppressing floating of the original in the second reading unit.

  Here, the document pick-up unit in the conventional automatic document feeder will be described with reference to FIG. The same reference numerals are used for the same parts as those in the automatic document feeder of the embodiment.

  In FIG. 4, a pickup roller 57 is operated by a pickup motor in the c and d directions shown in the drawing by a pickup motor, and the movable table 3 is lifted and pushed by the upper surface of the original on the movable table 3 in the c direction. The upper limit can be detected by the table rise detection sensor 58. The pickup roller 57 rotates in a direction to convey the uppermost document to the sheet feeding port, and picks up several (ideally one) documents on the document table 2. Thereafter, the original separated into one sheet by the action of the paper feed belt 9 and the reverse roller 10 is further fed by the paper feed belt 9, and the leading edge is detected by the abutting sensor 11. After the detection, the document further advances, and the pickup roller 57 stops rotating and rises. When the original is further transported and the trailing edge of the original is detected by the abutting sensor 11, the pickup roller 57 is lowered again and the next original is fed. Further, since the gap between the pickup roller 57 and the upper surface of the document increases each time the document is conveyed, the movable table 3 is configured to be lifted by the table lift detection sensor 58 when the gap is increased beyond a certain level. In pursuing further speedup, in the conventional configuration, it takes 60 ms for the pickup to descend, and during this 60 ms, the interval between the previous document and the next document increases, and the productivity (the number of sheets that can be read per minute) is increased. ) Has become an obstacle to increasing.

Next, the present invention will be described with reference to FIGS.
FIG. 5 is an enlarged view showing a document pickup section in the automatic document feeder of this embodiment. The pickup roller 7 is fixed at a fixed position (with a configuration that does not move up and down) and is rotatably provided. As shown in FIG. 8, the pick-up roller 7 has one or a plurality of cut surfaces 7b, and is always kept in a state where the cut surface is down except during rotation. When the set filler 4 and the set sensor 5 detect that the document P is set, the movable table 3 rises, and the upper surface of the document can be detected by detecting the upper surface of the document on the movable table 3 by the document surface detection means 8. Yes. The pickup roller 7 rotates in a direction to convey the uppermost document to the paper feed port, and picks up several (ideally one) documents on the document table 2. After that, the pickup roller 7 is rotated to the next cut surface, and the configuration is such that the cut surface is turned down and stopped (with the cut surface facing the document surface).

  The control for stopping the cut surface of the pickup roller 7 toward the document surface is a method in which the drive motor is a pulse motor (stepping motor) and controlled by the number of drive pulses, or the position of the cut surface or rotation of the roller by providing some sensor. A method of detecting and controlling a corner or the like can be employed.

  Now, if the pickup roller 7 rotates and the next cut surface (the next circumference if there is one cut surface) comes, but the leading edge of the document does not reach the abutting sensor 11, the pickup roller 7 is further moved. Rotate to the cut surface. If it still does not reach the abutment sensor 11, it is determined that the document jam has occurred, and driving is stopped. Further, when the document is further conveyed and the trailing edge of the document is detected by the abutting sensor 11, the next document feeding operation is started. Further, since the gap between the pickup roller 7 and the upper surface of the original document increases every time the original document is conveyed, the upper surface position of the original document is detected by the original surface detecting means 8 so that the upper surface of the original document bundle is always maintained at substantially the same height. Further, the movable table 3 is controlled. With this configuration, there is no need to move the pickup roller up and down (up and down) as in the conventional apparatus, the timing of feeding the next original can be advanced, and productivity can be improved.

  FIGS. 6A and 6B are diagrams for explaining the configuration and operation of the document surface detecting means 8, wherein FIG. 6A is a top view of the document surface detecting means 8 as viewed from above, and FIG. 6B is a pickup roller 7 for explaining the operation. FIG.

As shown in FIG. 6, the document surface detection means 8 includes a sensor 81 and a filler 82, and is arranged in the vicinity of the pickup roller 7.
For example, a transmissive optical sensor can be used as the sensor 81, and includes a light emitting unit 81a and a light receiving unit 81b. When the light emitted from the light emitting unit 81a is received by the light receiving unit 81b, the sensor output is turned ON.

  The filler 82 is supported by a shaft 83 and can be rotated (swinged) as indicated by double arrows e and f in FIG. An upper end portion (a portion above the shaft 83) 82a of the filler 82 is disposed between the light emitting portion 81a and the light receiving portion 81b in the space portion of the sensor 81 having an inverted “U” shape.

  (B) When the filler 82 is descending as shown by a broken line in the figure, (a) the filler upper end 82a blocks the sensor light as shown in the upper part of the figure, and the sensor output is OFF. Then, as the movable table 3 is raised, the filler 82 is further rotated (clockwise in the figure) from the position indicated by the solid line in FIG. When light is withdrawn from between the light emitting portion 81a and the light receiving portion 81b, the light emitted from the light emitting portion 81a is received by the light receiving portion 81b, and the sensor output is turned ON. In this embodiment, when the output of the sensor 81 is OFF, the movable table 3 is raised by the normal rotation driving of the bottom plate raising motor 105. When the output of the sensor 81 is turned on, the bottom plate raising motor 105 is stopped and the movable table 3 is stopped. As a result, the upper surface position of the document bundle P set on the movable table 3 is always maintained at substantially the same height.

  The configuration of the document surface detection unit 8 is an example, and an appropriate configuration can be adopted. For example, the structure which detects a filler using a reflection type sensor is also possible. In addition, a combination of an appropriate sensor and filler can be employed. The filler is not limited to swinging but may be of a sliding type.

  By the way, as can be seen from FIG. 6B, the sensor output is OFF in the range where the filler 82 that has been lowered downwards rises (rotates) to the position indicated by the solid line. That is, the output of the sensor 81 is OFF until the upper surface of the document that pushes up the filler 82 reaches the extended line on the outer periphery of the pickup roller 7 indicated by a dotted line in the drawing.

  As the movable table 3 is raised, the upper surface of the document is further raised so that the sensor 81 is turned on only after entering the outer peripheral extension line of the pickup roller 7, that is, within the range of the cut portion 7b of the pickup roller 7. It has a configuration.

  As described above, the sensor 81 is turned on only when the upper surface of the original falls within the range of the cut portion 7b of the pickup roller 7, so that the original can be reliably sent out when the pickup roller 7 is rotated. Non-feed can be prevented. That is, due to an error between the sensor 81 and the filler 82 (a situation where the sensor is turned on and the movable table 3 is stopped in a range where the upper surface of the original cannot contact the peripheral surface of the pickup roller 7 is prevented) is brought into contact with the pickup roller 7 and the original. It prevents the situation that does not occur.

FIG. 7 is a diagram showing another example of the document surface detection means.
The document surface detection means 180 shown in this figure has a non-contact type sensor 181 such as an optical sensor or an ultrasonic sensor. In addition, a document pressing member 182 is provided to prevent erroneous detection due to document curling. The document pressing member 182 includes a spring 183, a rib 184, and a movable portion 185, and is movable up and down. One or a plurality (two in this example) are provided. The top surface of the document is positioned by detecting the position of the top surface of the document pressed by the document pressing member 182 with the non-contact type sensor 181. The sensor 181 is set to be turned on only when the upper surface of the document enters the range of the cut portion 7b of the pickup roller 7.

  The document surface detection means 8 or 180 is disposed in the vicinity of the pickup roller 7. By providing such a document surface detection means 8 or 180, an accurate gap between the document upper surface and the pickup roller can be detected even if the pickup roller 7 is configured to be fixed (a configuration that does not move up and down). .

FIG. 8 is a cross-sectional view showing the shape of the pickup roller 7.
As shown in this figure, the pickup roller 7 has an arc portion 7a and a cut portion 7b obtained by cutting a part of the outer peripheral surface. As described above, the pickup roller 7 is controlled so as to always stop with the cut portion 7b (cut surface) facing down except during rotation. After the preceding document is sent out, the pickup roller 7 is stopped with the cut portion 7b (cut surface) facing down, so that it is not necessary to raise and retract the pickup roller for paper separation as in the conventional apparatus. In addition, since it is not necessary to lower the pickup roller for the next document, it is possible to eliminate the lifting and lowering time of the pickup roller, to advance the timing of feeding the next document, and to improve productivity.

  By the way, as shown in FIG. 8, in the pickup roller 7 of this embodiment, the connecting portion between the arc portion 7a and the cut portion 7b is configured as a rounded R-shaped portion. By adopting such a configuration, it is possible to eliminate the catch when the pickup roller 7 rotates, and to suppress the chipping and wear of the roller by smooth rotation.

FIG. 9 shows a configuration example in which a plurality of pickup rollers 7 (two in the illustrated example) are provided.
The two pickup rollers 7 and 7 arranged in the transport direction have the configuration described with reference to FIG. 8. As shown in FIG. 8A, the cut surface 7 b is always down (paper surface) except during rotation for transporting a document. In the direction of).

  Here, as shown in FIG. 5B, it is preferable that the drive timing of the pickup rollers 7 and 7 is shifted so that at least one pickup roller 7 is always in contact with the original while the pickup roller 7 is transporting the original. It is. Thereby, even when the diameter of the pickup roller is small, a long distance can be conveyed.

  As described above, the automatic document feeder according to the present embodiment is configured as a sheet-through ADF. In the image reading apparatus equipped with the sheet-through ADF, the image reading unit is fixed (stopped). The original is conveyed by ADF to the original reading position (denoted by reference numeral 20 in FIG. 1), and the original image is read while being conveyed at a predetermined speed. Further, in the illustrated example, a second reading unit 25 that reads the back side of the document is also provided.

  The automatic document feeder of the present invention is not limited to a sheet-through type reading device, but is also applicable to a device that reads a document stopped on a contact glass surface while the reading unit is running (referred to as a document stop method). Is possible.

An example of an image forming apparatus having such a document stop type image reading apparatus and automatic document feeder will be described with reference to FIG.
The image forming apparatus shown in FIG. 10 is a so-called tandem type full-color apparatus, and includes an image reading unit and is configured as a copying apparatus. The copying apparatus of this example has an apparatus main body 310 mounted on a paper feed table 320, a scanner 330 is disposed at the top of the apparatus main body 310, and an automatic document feeder (ADF) 340 is further provided thereon. is there.

  The ADF 340 is applicable to the present invention, and includes the movable document table 3 and the pickup roller 7 as described in the above embodiment. Document surface detection means 8 (see FIG. 5) is provided in the vicinity of the pickup roller 7. The pickup roller 7 includes the cut portion 7b described with reference to FIG.

  Inside the scanner 330, a first traveling body 331 composed of an illumination light source and a mirror and a second traveling body 332 including a mirror are provided so as to be movable in parallel with the contact glass 333. The second traveling body 332 employs a known optical system that moves at half the speed of the first traveling body 331, and these traveling bodies 331 and 332 are stopped on the contact glass 332 while moving. Scan the original image. Reflected light from the original illuminated by the light source is imaged by a condenser lens 334 and taken into a solid-state imaging device 335 such as a CCD. The data is processed by the image processing unit of the copying apparatus main body.

  An intermediate transfer belt 301 is disposed almost at the center of the copying apparatus main body 110. Four image forming units 302 are arranged side by side along the upper side of the intermediate transfer belt 301. In each image forming unit 302, devices necessary for the electrophotographic process are arranged around the photosensitive drum 303.

  The intermediate transfer belt 301 is stretched around a plurality of support rollers so as to be able to rotate and convey clockwise in the drawing. Inside the intermediate transfer belt 301, a transfer roller as a primary transfer unit is disposed at a position facing the photosensitive drum 303 of each image forming unit.

  An exposure device 304 is disposed above each image forming unit 302. Write light from the exposure device 304 is applied to the photosensitive drum 303 of each image forming unit 302.

  A transfer conveying belt 305 is disposed below the intermediate transfer belt 301. One roller supporting the transfer conveyance belt 305 is configured as a secondary transfer roller, and secondarily transfers the image on the intermediate transfer belt 301 to a recording medium (transfer paper or the like).

  A fixing device 306 is provided on the left side of the transfer conveyance belt 305. A paper discharge tray 307 is provided on the left side of the fixing device 306. A sheet reversing unit 308 is provided at the lowermost part of the apparatus main body 310. The paper feed table 320 is provided with two stages of paper feed cassettes 321 and 322.

  Now, when making a copy using the color copying apparatus of this example, the original is set on the original table 2 of the ADF 340 or the contact glass 333 of the scanner. Then, when a start switch provided on an operation panel (not shown) is pressed, the scanner is driven, and reflected light from the light source is reflected by a mirror to enter a reading sensor through an imaging lens (not shown) to read document information.

  Similarly, when a start switch provided on the operation panel is pressed, the intermediate transfer belt 301 is rotated and conveyed by a drive motor (not shown). At the same time, the photoconductors 303 are rotated in the individual image forming units 302 to form black, yellow, magenta, and cyan single color images on the photoconductors 303, respectively. These single color images are sequentially transferred onto the intermediate transfer belt 301 to form a composite color image.

When the start switch is pressed, the paper is fed out from the paper feed table 320 and abuts against the registration roller 309 to be temporarily stopped.
Then, the registration roller 309 is rotated in synchronization with the composite color image on the intermediate transfer belt 301, the sheet is fed between the intermediate transfer belt 301 and the transfer conveyance belt 305, and the image is transferred by the secondary transfer unit. Record a color image on paper. The paper after the image transfer is sent to the fixing device 306, where the toner image is fixed and discharged to the paper discharge tray 307.

  As mentioned above, although this invention was demonstrated by the example of illustration, this invention is not limited to this. For example, the diameter of the pickup roller and the size of the cut portion can be set as appropriate. Further, the number of cut portions of the pickup roller is not limited to one and may include a plurality of cut portions. The document surface detection means can also adopt an appropriate configuration.

  The automatic document feeder to which the present invention is applied is not limited to the sheet-through method, and can be applied to an image reading device of a document stop method. Further, the image forming apparatus is not limited to a full-color machine, and may be a multi-color machine or a monochrome apparatus having a plurality of colors. Of course, the image forming apparatus is not limited to a copying machine, but may be a facsimile machine or a multifunction machine having a plurality of functions.

1 Seat-through ADF
DESCRIPTION OF SYMBOLS 3 Movable original table 2 Original table 4 Set filler 5 Set sensor 8 Original surface detection means 7 Pickup roller 7b Cut part 9 Paper feed belt 10 Reverse roller 20 Reading position 81 Sensor 82 Filler 100 Controller part 101-105 Drive part 180 Original surface detection Means 182 Document holding member 310 Copying device body 330 Scanner 340 Automatic document feeder (ADF)

JP 2007-254146 A

Claims (8)

In an automatic document feeder having a document stacking unit for setting a document, and a pickup roller for calling and transporting the document set on the document stacking unit,
The pick-up roller has at least one cut portion obtained by cutting a part of the peripheral surface, and is rotationally driven by a driving unit in a fixedly arranged state, and when stopped, the cut portion is stopped toward the document surface. As well as being controlled
The document stacking means is provided to be movable so as to approach and separate from the pickup roller,
In the vicinity of the pickup roller, there is provided a document surface detecting means for detecting the upper surface position of the document stacked on the document stacking means,
The automatic document feed is characterized in that the position of the upper surface of the document set on the document stacking means with respect to the pick-up roller is always maintained at substantially the same position based on the detection output of the document surface detection means. apparatus.   The document surface detecting means detects the document surface when an upper surface of the document set on the document stacking means approaches an inner side of a roller outer peripheral extension line in the cut portion of the pickup roller. Item 2. The automatic document feeder according to Item 1.   3. The automatic document according to claim 1, wherein the document surface detection unit includes a filler member that is swingably or slidably provided and contacts the document surface, and a sensor that detects the filler member. 4. Feeder.   The document surface detecting means includes a non-contact type sensor that detects a document surface in a non-contact manner, and at least one document pressing member that is disposed in the vicinity of the non-contact type sensor and presses the document. Item 3. The automatic document feeder according to Item 1 or 2.   2. The automatic document feeder according to claim 1, wherein the pickup roller is configured such that a connection portion between the cut portion and the arc portion is rounded in a curved shape.   2. The automatic document feeder according to claim 1, wherein a plurality of the pick-up rollers are provided, and the driving timing of each pick-up roller is controlled to be shifted.   An image reading apparatus comprising the automatic document feeder according to claim 1. An image forming apparatus comprising the automatic document feeder according to any one of claims 1 to 6 or the image reading device according to claim 7.

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