JP5565661B2 - Document conveying apparatus, image reading apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to a document conveying device and an image reading device. The present invention also relates to an image forming apparatus such as a copying machine or a facsimile provided with an image reading apparatus.

  2. Description of the Related Art Conventionally, an image reading apparatus equipped with an automatic document feeder (ADF: auto document feeder) as a document feeder is known. This image reading apparatus irradiates an image surface of a document with light from a light source inside the image reading unit through a translucent member while transporting the document by ADF. Then, the reflected light from the document image surface is received by the image sensor via the translucent member, and the image is read. In this type of image reading apparatus, when a document image is read, the document passes while being in contact with the light transmissive member. Therefore, it is inevitable that dust on the image surface side of the document adheres to the light transmissive member. Further, when an adhering substance such as dust adheres to the reading position of the translucent member, the effect appears on the read image signal, resulting in a so-called vertical streak connected in the sub-scanning direction, resulting in significant image degradation. End up.

  Patent Document 1 describes an image reading apparatus that includes an endless belt that faces a translucent member with a predetermined distance and a charging unit that charges the endless belt. The image reading apparatus described in Patent Document 1 sucks a document on an endless belt, conveys the document at a predetermined distance from the translucent member at a reading position, and reads a document image separated from the translucent member. With this configuration, the document is conveyed without rubbing against the translucent member. As a result, it is possible to prevent dust or the like on the image surface side of the document from dropping from the document due to sliding with the translucent member and adhering to the reading position of the translucent member. Therefore, it is possible to suppress the occurrence of vertical stripes in the read image, and it is possible to suppress the deterioration of the read image.

  However, for example, due to fluctuations in the speed of the endless belt caused by the eccentricity of the stretching roller that stretches the endless belt, a pair of transport rollers as a first document transport unit that is adjacent to the endless belt and disposed upstream in the document transport direction ( Hereinafter, a speed difference may occur between the first conveying roller pair) and the endless belt. In addition, there may be a difference in speed between the endless belt and a pair of transport rollers (hereinafter referred to as a second transport roller pair) that is adjacent to the endless belt and is downstream of the document transport direction as a second document transport unit. When the document is being transported by the endless belt and the first transport roller pair upstream of the endless belt in the document transport direction, if a speed difference occurs between the endless belt and the first transport roller pair, the endless belt of the document The portion adsorbed on the surface is pulled or pushed in by the conveying force of the first conveying roller pair. As a result, there is a problem that the original adhering to the endless belt is peeled off from the surface of the endless belt, the distance between the original and the translucent member varies, and the original image cannot be read satisfactorily. Further, when a document is being transported by the endless belt and the second transport roller pair downstream of the endless belt in the document transport direction, if a speed difference occurs between the endless belt and the second transport roller pair, The portion adsorbed on the endless belt is pulled or pushed in by the conveying force of the second conveying roller pair. As a result, the document is peeled off from the surface of the endless belt, the distance between the document and the translucent member fluctuates, and there arises a problem that the image of the document cannot be read well.

  The present invention has been made in view of the above problems, and an object of the present invention is to suppress the peeling of a document from the conveyance belt even if a speed difference occurs between the conveyance belt and the document conveyance means adjacent to the conveyance belt. It is an object of the present invention to provide an original conveying apparatus, an image reading apparatus, and an image forming apparatus that can perform the above operation.

In order to achieve the above object, the invention of claim 1 is arranged to face the light transmitting member of the image reading means with a predetermined distance in order to achieve the above object. In a document conveying apparatus that includes a conveying belt and an adsorbing unit that adsorbs an original to the conveying belt, and adsorbs the original to the conveying belt and conveys the original to a reading position of the image reading unit. A conveyance roller that is adjacent and has a driving roller that rotates in the document conveyance direction, and a driven roller that is driven to rotate in contact with the driving roller, and conveys the document while sandwiching the nip between the driving roller and the driven roller. A first document conveying means comprising a pair of rollers and disposed upstream of the conveying belt in the document conveying direction, a driving roller adjacent to the conveying belt and rotating in the document conveying direction, and a pressure contact with the driving roller A driven roller that rotates in contact with the driven roller, and includes a conveying roller pair that conveys the document while sandwiching the nip between the driving roller and the driven roller, and is disposed downstream of the conveying belt in the document conveying direction. and a second document conveying means, by changing the pressure to the drive roller of the driven roller of the first document conveying means, a first conveying force changing means for changing the original conveying force of the first document conveying means, the A second conveying force changing unit configured to change a document conveying force of the second document conveying unit by changing a pressure applied to the driving roller of the driven roller of the second document conveying unit; and a leading end of the document reaches the conveying belt. Until the leading edge of the document reaches the reading position, the first transport force changing unit is controlled so that the document transport force of the first document transport unit is less than a predetermined document transport force. Document tip Before reaching the second document conveying means, the document conveying force of the second document conveying means is weaker than a predetermined document conveying force, and after the trailing edge of the document reaches the reading position, Control means for controlling the second conveying force changing means so as to return the original conveying force of the second original conveying means to a predetermined original conveying force until the end is separated from the conveying belt, and detects an abnormal conveyance of the original. An abnormality detecting means for detecting the first original conveying force so that the pressure applied to the driving roller of the driven roller of the first original conveying means is weakened when the abnormality detecting means detects an abnormality in the original conveying. The changing means is controlled, and the second original conveying force changing means is controlled so that the pressure applied to the driving roller of the driven roller of the second original conveying means is weakened.
According to a second aspect of the present invention, there is provided the first document position for determining whether or not the leading edge of the document attracted to the surface of the transport belt reaches a predetermined amount upstream from the reading position in the document transport apparatus according to the first aspect. Determining means, and when the first document position determining means determines that the leading edge of the document has reached a predetermined amount upstream from the reading position, the control means determines the document conveying force of the first document conveying means to a predetermined value. The first document conveying force changing means is controlled so as to be weaker than the original document conveying force.
According to a third aspect of the present invention, there is provided the second document position determining means for determining whether or not the trailing edge of the document has passed the first document conveying means in the document conveying device according to the first or second aspect. When the second document position determining unit determines that the trailing edge of the document has passed through the first document transport unit, the control unit determines the document transport force of the first document transport unit to be a predetermined document transport. The first document conveying force changing means is controlled to return to the force.
According to a fourth aspect of the present invention, in the original conveying apparatus according to any one of the first to third aspects, the third original position for determining whether or not the leading edge of the original has reached a predetermined amount upstream from the second original conveying means. And determining means, and when the third document position determining means determines that the leading edge of the document has reached a predetermined amount upstream from the second document conveying means, the document of the second document conveying means The second document conveyance force changing means is controlled so that the conveyance force is weaker than a predetermined document conveyance force.
According to a fifth aspect of the present invention, in the original conveying apparatus according to any one of the first to fourth aspects, the apparatus further comprises fourth original position determining means for determining whether the trailing edge of the original has passed the reading position. When the fourth document position determining unit determines that the trailing edge of the document has passed the reading position, the second document transport unit returns the document transport force of the second document transport unit to a predetermined document transport force. The force changing means is controlled .
According to a sixth aspect of the present invention , in the original conveying apparatus according to any one of the first to fifth aspects, the first original conveying force changing means and the second original conveying force changing means use a solenoid to drive the driven roller. It is characterized in that it is configured to change the pressure applied to.
According to a seventh aspect of the present invention, there is provided an image reading apparatus including a document conveying unit that conveys a document and an image reading unit that reads a document image of the document conveyed by the document conveying unit. The document feeder according to any one of claims 1 to 6 is used.
The invention of claim 8 is an image reading apparatus, an image forming apparatus and an image forming means for forming an image based on the original image read by said image reading apparatus, as the image reading apparatus, according to claim 7 The image reading apparatus is provided.

According to the present invention, the document conveying force of the first document conveying means is determined by the predetermined document conveying force between the time when the leading edge of the document reaches the surface of the conveying belt and the time when the leading edge of the document reaches the reading position. Also weaken. As a result, the document conveying force of the first document conveying unit acting on the portion of the document adsorbed to the conveying belt when a speed difference occurs between the conveying belt and the first document conveying unit during document image reading. The pulling force and pushing force caused by the above can be reduced as compared with the case where the first original conveying means conveys the original with a predetermined original conveying force.
Further, the document conveying force of the second document conveying unit is made weaker than the predetermined document conveying force until the leading edge of the document reaches the second document conveying unit. As a result, the document conveying force of the second document conveying unit acting on the portion of the document adsorbed to the conveying belt when a speed difference occurs between the conveying belt and the second document conveying unit during document image reading. The pulling force and the pushing force due to can be reduced as compared with the case where the second original conveying means conveys the original with a predetermined original conveying force.
Therefore, during the document image reading, the portion adhering to the conveyance belt of the document is peeled off from the surface of the conveyance belt by the pulling force or pushing force by the document conveyance force of the first and second document conveyance means. This can be suppressed as compared with the case where the second original conveying unit conveys the original with a predetermined original conveying force.
Further, since the document conveying force of the second document conveying means is returned to the predetermined document conveying force after the trailing edge of the document reaches the reading position and until the trailing edge of the document is separated from the conveying belt, the second document Compared with the case where the document conveying force of the conveying unit is not returned to the predetermined document conveying force, the document after being separated from the conveying belt can be conveyed better by the conveying force of the second document conveying unit.

  According to the present invention, even when a speed difference occurs between the conveying belt adjacent to the conveying belt and the conveying belt during image reading, it is possible to suppress the peeling of the original from the conveying belt surface. The original image can be read.

1 is a schematic configuration diagram showing a copying machine according to an embodiment. FIG. 3 is a partially enlarged configuration diagram illustrating an enlarged part of the internal configuration of the image forming unit of the copier. FIG. 2 is a perspective view illustrating a configuration of a scanner and an ADF of the copier. The expanded block diagram which shows the principal part structure of ADF with the upper part of a scanner. The block diagram which shows a part of electric circuit of ADF and a scanner. The block diagram which shows the principal part of the electric circuit of the 2nd fixed reading part of ADF. The block diagram which shows the periphery of the 1st fixed reading part at the time of original reading. The schematic block diagram of an upstream conveyance force change mechanism. FIG. 6 is a control flow diagram of change processing for changing the conveying force of a reading entrance roller pair and the conveying force of a reading exit roller pair. Explanatory drawing of operation | movement with the upstream conveyance force change mechanism and downstream conveyance force change mechanism in each flow. FIG. 5 is a control flow diagram of document conveyance abnormality processing.

  Hereinafter, an embodiment in which the present invention is applied to a copying machine (hereinafter simply referred to as a copying machine) as an electrophotographic image forming apparatus will be described. First, a basic configuration of the copying machine according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram showing the copying machine. As shown in FIG. 1, this copier is a document transport reading unit 1 that is an image reading device for reading an image of a document MS, and an image that forms an image based on image data acquired by the document transport reading unit 1. An image forming unit 2 that is a forming unit and a paper feeding unit 30 that feeds transfer paper that is a recording material to the image forming unit 2 are provided.

  First, the configuration of the image forming unit 2 will be described. FIG. 2 is a partially enlarged configuration diagram illustrating an enlarged part of the internal configuration of the image forming unit. As shown in FIGS. 1 and 2, the image forming unit 2 includes four process units 3K, Y, M, and C that form toner images of respective colors of black, yellow, magenta, and cyan. Subscripts K, Y, M, and C indicate black, yellow, magenta, and cyan, respectively. Each of the process units 3K, Y, M, and C includes photoconductors 4K, Y, M, and C that are image carriers that carry toner images of respective colors. Around each of these photoreceptors 4K, Y, M, and C, there are charging devices 5K, Y, M, and C for uniformly charging the surface of each photoreceptor 4, and electrostatic latent images formed on each photoreceptor 4 surface. Developing devices 6K, Y, M, and C for developing an image, and photosensitive member cleaning devices 7K, Y, M, and C for cleaning the surface of each photosensitive member 4 after transfer of a toner image are provided. The process units 3K, Y, M, and C support the photosensitive members 4K, Y, M, and C and various devices disposed around the process units as a single unit on a common support. The forming unit 2 is detachable from the main body.

  Further, the image forming unit 2 forms an electrostatic latent image by irradiating a uniformly charged surface of each of the photoreceptors 4K, Y, M, and C with laser light corresponding to image information. It has. The optical writing device 8 includes a laser light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and the surface of each photoconductor 4K, Y, M, C that is rotationally driven based on image data at a predetermined exposure position. The laser beam is irradiated while scanning in the main scanning direction.

  The image forming unit 2 also includes a transfer unit 10 that transfers the toner images formed on the photoreceptors 4K, Y, M, and C to the transfer paper via the intermediate transfer belt 9, and a fixing device that fixes the toner image on the transfer paper. 20 mag.

  The transfer unit 10 includes an intermediate transfer belt 9 that is stretched by a plurality of rollers and is driven to rotate in the direction of the arrow in the figure, and a primary transfer roller 11K to which a predetermined voltage is applied to the photoreceptors 4K, Y, M, and C. , Y, M, and C, the intermediate transfer belt 9 is sandwiched to form a primary transfer nip. The intermediate transfer unit 10 forms a secondary transfer nip by sandwiching the intermediate transfer belt 9 between the secondary transfer backup roller 12 and the secondary transfer roller 13 to which a predetermined voltage is applied. The intermediate transfer unit 10 further includes a cleaning device 14 that removes transfer residual toner remaining on the intermediate transfer belt 9. The toner images on the photoreceptors 4K, Y, M, and C formed by the process units 3K, Y, M, and C are sequentially superimposed and transferred onto the intermediate transfer belt 9 at the primary transfer nip. The four-color superimposed toner images transferred onto the intermediate transfer belt 9 are collectively transferred onto the transfer paper at the secondary transfer nip. The transfer residual toner remaining on the intermediate transfer belt 9 after passing through the secondary transfer nip is removed by the cleaning device 14.

  Below the transfer unit 10 in the drawing, an endless paper transport belt 16 is stretched between the secondary transfer roller 31 and the driving roller 15 to move endlessly, a pair of registration rollers 18, a fixing roller 18 and a fixing roller. The apparatus 20 etc. are provided. The registration roller pair 18 sandwiches the transfer paper supplied via a paper feed path 19 by a paper feed unit, which will be described later, between the rollers, and enters the secondary transfer nip at a timing that can be synchronized with the four-color toner image on the intermediate transfer belt 9. Send it out. The transfer paper on which the full-color image has been transferred through the secondary transfer nip is separated from the intermediate transfer belt 9 and is conveyed to the fixing device 20 along with its endless movement while being held on the paper conveyance belt 16. . The transfer paper conveyed to the fixing device 20 is fixed to a full-color image by pressurization or heating in the fixing device 20, then sent from the fixing device 20 to the paper discharge roller pair 21, and then to the outside of the apparatus. Discharged.

  A switchback device 22 is provided below the paper transport unit 17 in the figure. The switchback device 22 reverses the transfer paper that has undergone image fixing processing on one side by switching the path of the transfer paper to the transfer paper reversing device side with a switching claw, and enters the secondary transfer nip again.

  The paper feeding unit 30 of the copying machine includes a plurality of paper feeding cassettes 31 for storing a plurality of transfer papers in a stack of paper sheets, and feeds the uppermost transfer paper in each paper feeding cassette 31. The paper roller 32 is pressed. When the selected paper feed roller 32 is driven to rotate, the uppermost transfer paper is separated by the separation roller 33 and sent out one by one toward the paper feed path 34. The transfer paper fed to the paper feed path 34 is guided to the paper feed path 19 in the image forming unit 2 through a plurality of conveying roller pairs 35 and is sandwiched between the rollers of the registration roller pair 18.

  In the image forming unit 2 configured as described above, image formation is performed as follows. For example, in the black process unit 3K, the surface of the photoconductor 4K uniformly charged by the charging device 5K is irradiated with the laser light L modulated and deflected by the optical writing device 8 while being scanned, thereby causing an electrostatic latent image. An image is formed. The electrostatic latent image on the photoreceptor 4K is developed by the developing device 6K and becomes a black toner image. In the primary transfer nip that faces the primary transfer roller 11K across the intermediate transfer belt 9, the toner image on the photoconductor 4K is transferred onto the transfer paper. The surface of the photoconductor 4K after the toner image is transferred is cleaned by the photoconductor cleaning device 7K to prepare for the formation of the next electrostatic latent image.

  For the other process units 3Y, 3M, and C, the above-described image forming process is executed in synchronization with the movement of the intermediate transfer belt 9. On the other hand, the transfer paper fed from the paper feed cassette 31 is sent at a predetermined timing by the registration roller pair 19 and conveyed to the secondary transfer nip. Alternatively, the transfer paper fed from the manual feed tray 23 installed on the side surface of the image forming unit 2 is fed out into the manual feed path by the feed roller 24 and sent out at a predetermined timing by the registration roller 28. It is conveyed to the next transfer nip. Then, the transfer paper on which the full color image is collectively transferred at the secondary transfer nip is transported by the paper transport unit 17 and the toner image is fixed by the fixing device 20. In the single-sided print mode in which an image is formed only on the first side of the transfer paper, the transfer paper sandwiched in the paper discharge nip between the rollers of the paper discharge roller pair 21 is directly discharged out of the apparatus and discharged to the paper discharge tray 25. Stacked on top. In the double-sided print mode in which images are formed on both sides of the transfer paper, the transfer paper sandwiched between the paper discharge roller pair 21 is returned in the reverse direction and enters the switchback device 22. Then, after being turned upside down in the switchback device 22, it is sent again to the secondary transfer nip and subjected to image secondary transfer processing and fixing processing on the other side, and then discharged by the discharge roller 21. The paper is discharged onto the paper tray 25. After the toner image has been transferred, the residual toner is removed by the belt cleaning device 14 and the intermediate transfer belt 9 is ready for image formation by the process unit 3 again.

  The above-described image forming operation is an operation when the full-color mode for superimposing four colors is selected by an operation unit (not shown). For example, when the black-and-white image forming mode is selected on the operation unit, the support rollers other than the driving roller are moved to move the photoreceptors 4Y, 4M, and 4C away from the intermediate transfer belt 9, and the intermediate transfer belt 9 Only the formation of a K toner image may be performed.

  Next, the document conveyance reading unit 1 as an image reading device will be described in detail. As shown in FIG. 1, the document conveying / reading unit 1 includes a scanner 40 serving as an image reading unit fixed on the image forming unit 2 and an ADF 41 serving as a document conveying device supported by the scanner 40. The scanner 40 includes a moving reading unit 42 and a first fixed reading unit 43 as reading means for reading an image of a document (not shown). The moving reading unit 42 is disposed directly below the contact glass 45 fixed to the upper wall of the casing of the scanner 40 so as to come into contact with the document MS, and includes a light source, a reflection mirror, and the like, and is movable in the left-right direction in the drawing. It has a carriage, an optical lens 46a fixed to the scanner 40 main body, an image reading sensor 46b, and the like. Then, in the process of moving the carriage from the left side to the right side in the figure, the light emitted from the light source is reflected by a document (not shown) placed on the contact glass 45 and then passed through a plurality of reflecting mirrors. Light is received by an image reading sensor 46 fixed to the scanner 40 main body.

  The first fixed reading unit 43 disposed in the scanner 40 is disposed immediately below a platen glass 47 which is a translucent member fixed to one end of the upper wall of the casing of the scanner 40, and includes a light source, a reflection mirror, and a CCD. And the like. The first fixed reading unit 43 passes the plurality of reflecting mirrors while sequentially reflecting the light emitted from the light source on the document surface when the document MS conveyed by the ADF 41 described later passes over the platen glass 47. The light is received by the image reading sensor. Accordingly, the first surface of the document MS is scanned without moving the optical system including the light source and the reflection mirror.

  FIG. 3 is a perspective view showing the configuration of the scanner 40 and the ADF 41. As shown in FIG. 3, the ADF 41 includes, on a main body cover 48 as a housing, a document placing table 49 for placing a document MS before reading, a transport unit 50 for transporting the document MS, and a document MS after reading. A document stacking table 57 for stacking the document.

  FIG. 4 is an enlarged configuration diagram showing the main configuration of the ADF 41 together with the upper portion of the scanner. As shown in FIG. 4, the transport unit 50 of the ADF 41 includes a separation feeding unit 51, a registration unit 52, a turn unit 53, a first reading transport unit 54, a second reading transport unit 55, and a paper discharge unit 56. Has been. The separation feeding unit 51 separates and feeds the originals MS one by one from the bundle of originals MS set on the original placement table 49. The registration unit 52 performs primary abutting alignment of the fed document MS, and pulls out and transports the aligned document MS. The turn portion 53 has a curved conveyance portion that is curved in a C shape, and conveys the document surface toward the reading portion side (downward) while folding the document MS in the curved conveyance portion. The first reading / conveying unit 54 conveys the document MS above the platen glass 47, while the first surface of the document MS is placed on the first fixed reading unit 43 disposed inside the scanner 41 below the platen glass 47. Is to be read. The second reading conveyance unit 55 causes the second fixed reading unit 44 to read the second surface of the document MS while conveying the document MS under the second fixed reading unit 44. The paper discharge unit 56 discharges the original MS from which both-side images have been read toward the original stack base 57.

  As shown in FIG. 3, the main body cover 48 of the ADF 41 is supported by a hinge 58 fixed to the scanner 40 so as to be swingable in the vertical direction. Then, the platen glass 47 and the contact glass 45 on the upper surface of the scanner 40 are exposed in the opened state by moving like an open / close door by the swing. In the case of a single-bound document such as a book in which one corner of a document bundle is bound, the documents cannot be separated one by one and cannot be transported by the transport unit 50. Therefore, in the case of a single-sided original, the main body cover 48 is opened as shown in FIG. 3, and then the single-sided original having the page to be read is opened face down and placed on the contact glass 45, and then the main body cover is opened. 48 is closed. Then, the image of the page is read by the moving reading unit 42 shown in FIG.

  On the other hand, in the case of a document bundle in which a plurality of independent documents MS are simply stacked, the first fixed reading unit 43 in the scanner 40 and the document MS set on the document placing table 49 are automatically conveyed one by one. The second fixed reading unit 44 in the ADF 41 can sequentially read. In this case, the ADF 41 sends the originals MS of the original bundles placed on the original placement stage 49 sequentially from the top into the transport unit 50 and transports them toward the original stacking stage 51 while inverting them. In the course of this conveyance, the original MS is passed immediately above the first fixed reading unit 43 immediately after being inverted. At this time, the image on the first surface of the document MS is read by the first fixed reading unit 43 of the scanner 40. Further, the second surface of the document MS is read by the second fixed reading unit 44.

  FIG. 5 is a block diagram showing a part of the electric circuit of the ADF and the scanner. As shown in FIG. 5, the ADF 41 includes a controller 60 made up of ASIC (Application Specific Integrated Circuit) and the like, and can control various devices and sensors. The controller 60 includes a registration sensor 61, a document set sensor 62, a paper discharge sensor 63, an abutment sensor 64, a document width sensor 65, a reading entrance sensor 66, a proper paper feed position sensor 67, and a bottom plate home position (HP) sensor 68. Etc. are connected. A second fixed reading unit 44, a pickup motor 71, a paper feed motor 72, a reading motor 73, a paper discharge motor 74, a bottom plate raising motor 75, and the like are also connected. A main body control unit 100 that controls each device of the scanner 40 is also connected. The scanner 40 includes a main body control unit 100 including a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like, which can control various devices and sensors (not shown). The main body control unit 100 is connected to the controller 60 of the ADF 41 via the I / F 77, and can also indirectly control various devices and sensors in the ADF 41 via the controller 60.

  In the ADF 41 having the above-described configuration, as shown in FIG. 4, the document MS has a document tip placed on a movable document table 59 that can swing in the directions of arrows a and b in the drawing according to the thickness of the bundle of documents MS. At the same time, the document is placed with the document trailing edge placed on the document table 49. At this time, the position in the width direction is adjusted by abutting side guides (not shown) against both ends in the width direction (direction orthogonal to the document conveyance direction) on the document placement table 49. The document MS set in this way pushes up a lever member 78 that is swingably disposed above the movable document table 59. Accordingly, the document set sensor 62 detects the setting of the document MS and transmits a detection signal to the controller 60. This detection signal is sent from the controller 60 to the main body control unit 100 via the I / F 77.

  The document placing table 49 is provided with a first document length detection sensor 79 and a second document length detection sensor 80 for detecting the length of the document MS in the transport direction. Detected. In the present embodiment, it is necessary to arrange at least a sensor that can determine whether the document size is vertical or horizontal. The first document length detection sensor 79 and the second document length detection sensor 80 may be a reflection type photo sensor or an actuator type sensor that can detect even one document.

  When the document set sensor 62 detects that the document MS is set on the movable document table 59, the main body control unit 100 rotates the bottom plate raising motor 75 so that the uppermost surface of the document bundle contacts the pickup roller 81. The movable document table 59 is raised. Then, the main body control unit 100 stops the ascending of the bottom plate when the appropriate paper feed position sensor 67 is turned on, and repeats the paper feeding to lower the upper surface of the document bundle and when the proper paper feed position sensor 67 is turned off, raises the bottom plate to supply the paper. The control is repeated so that the appropriate paper position sensor 67 is turned on again. As a result, the height of the movable document table 59 is adjusted, and the upper surface position of the document bundle is always maintained at a height suitable for paper feeding. When all the set originals MS are fed, the bottom plate raising motor 75 is rotated forward to lower the movable original table 59 to the home position so that the next original bundle can be set.

  A pickup roller 81 is disposed above the bundle of documents placed on the movable document table 59 and supported by a cam mechanism so as to be movable in the vertical direction (arrow c and d directions in the figure). This cam mechanism can be driven by a pickup motor 71 to move the pickup roller 81 up and down. When the pickup roller 81 moves upward, the movable document table 59 swings in the direction of arrow a in the drawing, and the pickup roller 81 contacts the uppermost document MS in the bundle of documents MS. When the movable document table 59 is further raised and the pickup roller 81 is pushed by the upper surface of the document on the movable document table 59 and moved up in the direction c, the upper limit of the movable document table 59 is detected by the proper paper feed position sensor 67. Is done. As a result, the pickup motor 71 is stopped and the raising of the movable document table 59 is stopped.

  For an operation unit 101 including a numeric keypad and a display provided in the main body of the copying machine, a key operation for setting a reading mode indicating a duplex scanning mode or a single-sided scanning mode by an operator, or a copy start key A pressing operation 102 is performed. Here, when setting the double-sided reading mode or the single-sided reading mode, the same setting may be made for all the documents set on the document placing table 49, or (first sheet, second sheet,. Different settings may be made for each original (for example, the nth sheet) (for example, out of a total of 10 originals, the first and tenth sheets are in the double-sided reading mode, and the others are in the single-sided reading mode).

  When the copy start key 102 is pressed, a document feed signal is transmitted from the main body control unit 100 to the controller 60 of the ADF 41 via the I / F 77. Then, the pickup roller 81 is rotationally driven by the forward rotation of the paper feed motor 72 to pick up several (ideally one) originals MS on the movable original table 59. The rotation direction of the pickup roller 81 is a direction in which the uppermost document MS is conveyed to the sheet feeding port.

  When setting the double-sided reading mode or the single-sided reading mode, it is possible to collectively set the double-sided or single-sided setting for all the originals MS placed on the movable original table 59. The first and tenth originals MS are set to the double-sided reading mode, while the other originals MS are set to the single-sided reading mode. Can also be set.

  The document MS sent out by the pickup roller 81 enters the separation conveyance unit 51 and is sent to a contact position with the paper feed belt 82. The paper feed belt 82 is stretched by a drive roller 83 and a driven roller 84, and is endlessly moved in the clockwise direction in the drawing by the rotation of the drive roller 83 accompanying the forward rotation of the paper feed motor 72. A reverse roller 85 that is driven to rotate in the clockwise direction in the drawing by the forward rotation of the paper feed motor 72 is in contact with the lower tension surface of the paper feed belt 82. At the contact portion, the surface of the paper feed belt 82 moves in the paper feed direction. On the other hand, the reverse roller 85 is in contact with the paper feed belt 82 with a predetermined pressure, and when the paper is in direct contact with the paper feed belt 82 or only one original MS is sandwiched between the contact portions. At that time, it is carried around the paper feed belt 82 or the document MS. However, when a plurality of documents MS are sandwiched between the contact portions, the accompanying force becomes lower than the torque of the torque limiter, and therefore the clock shown in the figure is the original driving direction opposite to the accompanying direction. Rotate around. As a result, a moving force in the direction opposite to the paper feeding direction is applied to the original document MS below the uppermost position by the reverse roller 85, and only the uppermost original MS is separated from the several original sheets MS, and the double feed is performed. Is prevented.

  The document MS separated into one sheet by the action of the paper feed belt 82 and the reverse roller 85 enters the registration unit 52. Then, the tip is detected when passing just below the butting sensor 64. At this time, the pickup roller 81 receiving the driving force of the pickup motor 71 is still driven to rotate. However, since the movable original table 59 is lowered, the original MS is separated from the original MS. Only conveyed by. The endless movement of the paper feed belt 82 continues for a predetermined time from the timing when the leading edge of the document MS is detected by the abutting sensor 64, and the leading edge of the document MS abuts against the nip portion of the pull-out roller pair 86. With the leading edge of the document MS abutting against the abutting portions of both rollers, the trailing edge of the document MS is fed in the paper feeding direction, so that the document MS is bent by a predetermined amount while the leading edge is bent. Positioned at the contact portion. As a result, the skew (inclination) of the document MS is corrected, and the document MS assumes a posture along the paper feeding direction.

  In addition to correcting the skew of the document MS, the pull-out roller pair 86 has a role of transporting the document MS whose skew has been corrected to the intermediate roller pair 87 on the downstream side in the document transport direction. It is rotationally driven by reverse rotation. When the paper feed motor 72 is reversely rotated, one roller of the pull-out roller pair 86 and one roller of the intermediate roller pair 87 start rotating, and the endless movement of the paper feed belt 82 is stopped. At this time, the rotation of the pickup roller 81 is also stopped.

  The document MS sent from the pull-out roller pair 86 passes directly below the document width sensor 65. The document width sensor 65 has a plurality of paper detection units made up of a reflection type photosensor and the like, and these paper detection units are arranged in the document width direction (a direction perpendicular to the drawing sheet). Based on which paper detection unit detects the document MS, the size of the document MS in the width direction is detected. Further, the length of the document MS in the conveyance direction is detected based on the timing from when the leading edge of the document MS is detected by the abutting sensor 64 until the trailing edge of the document MS is not detected by the abutting sensor 64. .

  The leading edge of the document MS whose size in the width direction is detected by the document width sensor 65 enters the turn portion 53 and is sandwiched between contact portions between the rollers of the intermediate roller pair 87. The conveyance speed of the document MS by the intermediate roller pair 87 is set to be higher than the conveyance speed of the document MS in the first reading conveyance unit 54 described later. As a result, the time until the document MS is sent to the first reading conveyance unit 54 is shortened.

  The leading edge of the document MS conveyed in the turn portion 53 passes through a position facing the reading entrance sensor 66. Thus, when the leading edge of the document MS is detected by the reading entrance sensor 66, the document conveying speed by the intermediate roller pair 87 is reduced while the leading edge is conveyed to the position of the reading inlet roller pair 89 on the downstream side in the conveying direction. The As the reading motor 73 starts to rotate, one roller in the reading inlet roller pair 89, one roller in the reading outlet roller pair 90, and one roller in the second reading outlet roller pair 91 are driven to rotate. Start.

  In the turn section 53, the upper and lower surfaces are reversed and the conveyance direction is folded while the document MS is conveyed on the curved conveyance path between the intermediate roller pair 87 and the reading entrance roller pair 89. Then, the leading edge of the document MS that has passed through the nip between the rollers of the reading entrance roller pair 89 passes immediately below the registration sensor 61. When the leading edge of the document MS is detected by the registration sensor 61 at this time, the document transport speed is reduced while applying a predetermined transport distance, and the transport of the document MS is temporarily stopped before the first reading transport unit 54. . Further, a registration stop signal is transmitted to the main body control unit 100 via the I / F 77.

  When the main body control unit 100 that has received the registration stop signal transmits a reading start signal, the rotation of the reading motor 73 is resumed until the leading edge of the document MS reaches the first reading conveyance unit 54 under the control of the controller 60. The conveyance speed of the document MS is increased to a predetermined conveyance speed. Then, at the timing when the leading edge of the document MS calculated based on the pulse count of the reading motor 73 reaches the reading position by the first fixed reading unit 43, the controller 60 sends the first surface of the document MS to the main body control unit 100. A gate signal indicating the effective image area in the sub-scanning direction is transmitted. This transmission is continued until the trailing edge of the document MS exits the reading position by the first fixed reading unit 43, and the first surface of the document MS is read by the first fixed reading unit 43.

  The document MS that has passed through the first reading conveyance section 54 passes through the reading exit roller pair 90 and is then detected by the paper discharge sensor 63. When the single-sided reading mode is set, it is not necessary to read the second side of the document MS by the second fixed reading unit 44 described later. Accordingly, when the leading edge of the document MS is detected by the paper discharge sensor 63, the forward rotation drive of the paper discharge motor 74 is started, and the lower paper discharge roller in the drawing roller pair 92 in the clockwise direction in the figure. Is driven to rotate. The timing at which the trailing end of the document MS exits the nip of the sheet discharge roller pair 92 is calculated based on the pulse count of the sheet discharge motor 74 after the discharge sensor 63 detects the leading edge of the document MS. Based on this calculation result, the drive speed of the paper discharge motor 74 is decelerated immediately before the trailing edge of the original MS comes out of the nip of the discharge roller pair 92, and the original MS is removed from the original stack table 57. Paper is discharged at a speed that does not pop out.

  On the other hand, when the double-sided reading mode is set, the timing until the paper MS reaches the second fixed reading unit 44 after the leading edge of the document MS is detected based on the pulse count of the reading motor 73. Is calculated. At that timing, a gate signal indicating an effective image area in the sub-scanning direction on the second surface of the document MS is transmitted from the controller 60 to the main body control unit 100. This transmission is continued until the rear end of the document MS leaves the reading position by the second fixed reading unit 44, and the second surface of the document MS is read by the second fixed reading unit 44. Thereafter, the document MS is discharged onto the document stacking table 57 as described above.

  The second fixed reading unit 44 serving as a reading unit is coated on the reading surface for the purpose of preventing reading vertical streaks caused by glue-like foreign matters adhering to the document MS adhering to the reading surface. . A second reading roller 93 serving as a document supporting unit that supports the document MS from the non-reading surface side (first surface side) is disposed at a position facing the second fixed reading unit 44. The second reading roller 93 functions to prevent the original MS from floating at the reading position by the second fixed reading unit 44 and to function as a reference white portion for acquiring shading data in the second fixed reading unit 44. I'm in charge. In this copying machine, the second reading roller 93 is used as the document supporting means for supporting the document at a position facing the second fixed reading unit 44. However, a guide plate-shaped member may be used.

  FIG. 6 is a block diagram illustrating a main part of an electric circuit of the second fixed reading unit 44. As shown in FIG. 6, the second fixed reading unit 44 includes a light source unit 44 a made up of an LED array, a fluorescent lamp, a cold cathode tube, or the like. Also, a plurality of sensor chips 44b arranged in the main scanning direction (direction corresponding to the document width direction), a plurality of OP amplifier circuits 44c individually connected to each sensor chip 44b, and individually connected to each OP amplifier circuit 44c. A plurality of A / D converters 44d are also provided. Furthermore, it also includes an image processing unit 44e, a frame memory 44f, an output control circuit 44g, an I / F circuit 44h, and the like.

  The sensor chip 44b includes a photoelectric conversion element called a contact image sensor (CIS: Contact Image Sensor) and a condenser lens. Before a document (not shown) enters the reading position by the second fixed reading unit 44, a lighting ON signal is sent from the controller 60 to the light source unit 44a. As a result, the light source unit 44a is turned on and irradiates the light toward the second surface of the document MS (not shown). The reflected light reflected by the second surface of the document MS is condensed on the photoelectric conversion element by the condensing lens and read as image information in the plurality of sensor chips 44b. Image information read by each sensor chip 44b is amplified by an OP amplifier circuit 44c and then converted to digital image information by an A / D converter 44e. The digital image information is input to the image processing unit 44e, subjected to shading correction and the like, and then temporarily stored in the frame memory 44f. After that, the data is converted into a data format acceptable by the main body control unit 100 by the output control circuit 44g, and then output to the main body control unit 100 via the I / F circuit 44h. Note that the controller 60 gives a timing signal, a light source lighting signal, a power source for notifying the timing at which the leading edge of the document reaches the reading position by the second fixed reading unit 44 (image data after that timing is treated as valid data). Etc. are output.

Next, a configuration around the characteristic first fixed reading unit in the copying machine will be described. FIG. 7 is a configuration diagram showing the periphery of the first fixed reading unit during document reading.
As shown in the figure, a conveyor belt 94 stretched between three stretch rollers 95a, 95b, and 95c is opposed to a platen glass 47, which is a translucent member, at a predetermined interval. A charging roller 98 is provided as an adsorbing means for charging by contacting the outer peripheral surface of the conveying belt 94 and electrostatically adsorbing the original on the surface of the conveying belt 94. The adsorption means is not limited to one using static electricity.

  The document MS transported to the transport belt 94 by the reading entrance roller pair 89 is sandwiched between the charged transport belt 94 and the pressure roller 99, and the document is electrostatically attracted to the transport belt 94. Specifically, the document is dielectrically polarized by the electric field of the conveying belt 94 whose surface is charged by the charging roller 98. Due to the dielectric polarization, a charge having a polarity opposite to the charged polarity on the transport belt 94 is generated on the guide belt side of the document MS, and the document MS is electrostatically adsorbed on the transport belt 94. The document MS electrostatically attracted to the conveyance belt 94 is conveyed by the conveyance belt 94 and passes through the reading position of the first fixed reading unit 43. As a result, the document MS is conveyed with a predetermined distance between the document MS and the platen glass 47. Then, the document MS that has passed through the reading position and is transported to the stretched portion of the stretch roller 95a that is the most downstream in the document transport direction is separated from the transport belt 94 due to curvature separation, and moves to the pair of reading exit rollers 90. As described above, the document can be conveyed at the reading position with a predetermined distance between the document MS and the platen glass 47. Accordingly, since the document MS does not rub against the platen glass 47, foreign matters such as dust attached to the document MS do not adhere to the reading position of the platen glass 47 due to the rub on the platen glass 47. Thereby, it is possible to suppress foreign matter from adhering to the reading position of the platen glass 47.

  Further, the pair of reading entrance rollers 89 serving as the first document conveying means is provided with an upstream conveying force changing mechanism 110 serving as the first conveying force changing means for changing the conveying force. Further, the reading exit roller pair 90 as the second document conveying means is provided with a downstream conveying force changing mechanism 120 as the second conveying force changing means for changing the conveying force.

FIG. 8 is a schematic configuration diagram of the upstream conveyance force changing mechanism 110.
As shown in the drawing, the upstream conveying force changing mechanism 110 includes a support mechanism that supports one end side of the reading entrance driven roller 89b so as to be movable in a direction perpendicular to the document surface, and the other end side of the reading entrance driven roller on the document side. A support mechanism that supports the movable surface in a direction perpendicular to the surface, an upstream actuator that moves one end side of the reading inlet driven roller 89b in a direction perpendicular to the original surface, and the other end side of the reading inlet driven roller on the original surface. And an upstream actuator that moves in a vertical direction. Each support mechanism includes a bearing 113 having a long hole extending in a direction perpendicular to the document surface, a spring 114 having one end fixed to the shaft of the reading inlet driven roller, the other end of the spring 114, and an iron core of the upstream solenoid 111. It is comprised with the plate-shaped member 112 fixed to 111a.

One end side and the other end side of the shaft of the reading inlet driven roller 89b are inserted into the long holes of the bearing 113, and one end of the spring 114 is fixed to both ends of the shaft. The plate-like member 112 is provided on the outer side in the axial direction than the pair of reading entrance rollers 89, and extends in the direction perpendicular to the document conveying surface. The reading entrance driven roller side end portion of the plate-like member 112 has a spring fixing portion bent in the axial direction, and the other end of the spring 114 is fixed to the spring fixing portion. Further, the iron core 111a of the upstream solenoid 111 provided on the reading inlet driving roller side is fixed to the end of the plate-like member 112 on the reading inlet driving roller side.
The driving force of the reading motor 73 is transmitted to the reading entrance driving roller 89a via a timing belt (not shown).

  When the upstream solenoid 111 is energized, as shown in FIG. 8B, the spring 114 is compressed, and the reading inlet driven roller 89b contacts the reading inlet driving roller 89a with a predetermined pressure. Yes. At this time, the document sandwiched between the reading entrance roller pair 89 is conveyed by a predetermined conveying force. When the energization of the upstream solenoid 111 is released, the iron core 111a is lowered by its own weight or the urging force of the spring, and the compression of the spring 114 is released as shown in FIG. As a result, the pressure applied to the reading inlet driving roller 89a by the reading inlet driven roller 89b is weakened. As described above, the pressure applied to the reading inlet driving roller 89a by the reading inlet driven roller 89b is weakened, so that the conveying force applied to the original by the reading inlet roller pair 89 is weakened.

  The downstream conveyance force change mechanism 120 has the same configuration as the upstream conveyance force change mechanism 110.

FIG. 9 is a control flow chart of a change process for changing the conveying force of the reading inlet roller pair 89 and the conveying force of the reading outlet roller pair 90, and FIG. 10 shows the upstream conveying force changing mechanism 110 and the downstream in each flow. FIG. 6 is an operation explanatory diagram with a conveyance force changing mechanism 120.
First, as described above, when the copy start key 102 is pressed and the conveyance of the original on the original table 49 is started (S1), the upstream solenoid 111 is turned on and the reading inlet driven roller 89b is turned on. The pressure applied to the reading entrance driving roller 89a is set to a predetermined value (S2). In the present embodiment, the upstream solenoid 111 is turned on immediately after the document conveyance is started. However, the upstream solenoid 111 is turned on when the leading edge of the document MS reaches the reading inlet roller pair 89. Any timing may be used as long as the pressure applied to the reading inlet driving roller 89a by the roller 89b can be a predetermined value. At this time, the downstream solenoid 121 is turned off (S3) to weaken the pressure applied to the reading outlet driving roller 90a by the reading outlet driven roller 90b.

  Next, as shown in FIG. 10A, the main body control unit 100 has reached the position where the leading edge of the document MS being sucked and conveyed on the surface of the conveying belt 94 reaches the upstream position by a distance D1 from the reading position. It is checked whether or not (S4). Specifically, the main body control unit 100 starts counting the driving pulses of the reading motor 73 formed of a stepping motor from the time when the registration sensor 61 detects the leading edge of the document MS, and the number of driving pulses reaches a predetermined value. Then, it is determined that the leading edge of the document MS has reached a position upstream by a distance D1 from the reading position. That is, in the present embodiment, the main body control unit 100 and the registration sensor 61 constitute a first document position determination unit. Further, the distance D1 is set to a value that takes into account a sufficient margin for the time required for the upstream solenoid 111 to operate and the time required for the mechanical mechanism to stabilize. Thus, when the leading edge of the document MS reaches the reading position, the pressure applied by the reading inlet driven roller 89b is weakened, and the conveying force of the reading inlet roller pair 89 with respect to the document is weakened.

  When the leading edge of the document MS has not reached the position upstream of the distance D1 from the reading position (NO in S4), the document MS receives a sufficient conveying force from the reading inlet roller pair 89, and at a predetermined conveying speed. It is conveyed to the reading position. Then, as shown in FIG. 10A, when the leading edge of the document MS reaches a position upstream of the distance D1 from the reading position (YES in S4), the driving of the upstream solenoid 111 is turned off (S5). Then, the iron core 111a of the upstream solenoid 111 is moved in the direction of the arrow in the figure by the biasing force of the spring 114, and the pressure applied to the reading inlet driving roller 89a by the reading inlet driven roller 89b is weakened. As a result, the conveyance force of the conveyance belt 94 is dominant in the document MS during document image reading. Therefore, when a speed difference is generated between the reading entrance roller pair 89 and the conveying belt 94, slip occurs between the reading entrance roller pair 89 and the original MS, and the portion of the original MS adsorbed to the conveying belt 94 is detected. The generation of a pulling force or a pushing force can be suppressed. As a result, it is possible to prevent the portion at the reading position of the document during reading of the document image from being separated from the surface of the conveyor belt 94, and a good document image can be obtained.

  In this embodiment, as shown in FIG. 10B, the reading inlet driven roller 89b is separated from the reading inlet driving roller 89a, and the pressure applied to the reading inlet driving roller 89a by the reading inlet driven roller 89b is 0. I have to. As a result, the conveying force of the reading inlet roller pair 89 to the original becomes zero, and the conveying force from the reading inlet roller pair 89 does not act on the original MS during original image reading. As a result, no pulling force or pushing force is generated in the portion of the document that is adsorbed to the conveyance belt, and the document being read is prevented from being separated from the surface of the conveyance belt 94.

  Next, the main body control unit 100 checks whether or not it is the first document conveyance (S6). In the case of conveying the first document (YES in S6), since the downstream solenoid 121 is already OFF, the process moves to step S8. On the other hand, in the case of conveying the second and subsequent originals (NO in S6), the downstream solenoid 121 is ON, so that the main body control unit 100 determines that the front end of the original is the reading outlet as shown in FIG. It is checked whether or not the position upstream from the roller pair 90 by the distance D2 has been reached. Whether the leading edge of the document MS has reached the position upstream from the reading exit roller pair 90 by the distance D2 is determined by driving the reading motor 73 from the time when the registration sensor 61 detects the leading edge of the document MS, as described above. Pulse counting is started, and determination is made based on whether or not the number of driving pulses has reached a predetermined value. That is, in the present embodiment, the main body control unit 100 and the registration sensor constitute a third document position determination unit. The distance D2 is set to a value that takes into account a sufficient margin for the time required for the downstream solenoid 121 to operate and the time required for the state of the mechanical mechanism to stabilize. As a result, when the leading edge of the document reaches the reading exit roller pair 90, the pressure applied by the reading exit driven roller 90b is weakened, and the conveying force of the reading exit roller pair 90 with respect to the document is weakened.

  As shown in FIG. 10B, when the leading edge of the document MS reaches a position upstream of the distance D2 from the reading exit roller pair 90 (YES in S7), the driving of the downstream solenoid 121 is turned off (S8). Then, the iron core 121a of the downstream solenoid 121 moves in the direction of the arrow in the figure by the urging force of the spring 124, and the pressure applied to the reading inlet driving roller 90a by the reading outlet driven roller 90b is weakened. As a result, the conveyance force of the conveyance belt 94 is dominant for the document during document image reading. Therefore, when a speed difference occurs between the reading exit roller pair 90 and the conveyance belt 94, slip occurs between the reading exit roller pair 90 and the original MS, and the portion of the original MS adsorbed to the conveyance belt 94 is detected. The generation of a pulling force or a pushing force can be suppressed. As a result, it is possible to prevent the portion at the reading position of the document during reading of the document image from being separated from the surface of the conveyor belt 94, and a good document image can be obtained.

  In the present embodiment, as shown in FIG. 10C, the reading outlet driven roller 90b is separated from the reading outlet driving roller 90a, and the pressure applied to the reading outlet driving roller 90a by the reading outlet driven roller 90b is set to zero. Yes. As a result, the conveying force of the reading exit roller pair 90 with respect to the original becomes zero, and no pulling force or pushing force is generated in the portion adsorbed to the original conveying belt, and the original reading position during the original image reading is not generated. This prevents the portion located at the distance from the surface of the conveyor belt 94.

  Next, the main body control unit 100 checks whether or not the trailing edge of the document MS has passed through the reading entrance roller pair 89 (S9). Specifically, when the reading entrance sensor 66 detects the trailing edge of the document, the driving pulse of the reading motor 73 is started. When the number of driving pulses reaches a predetermined value, the trailing edge of the document is moved to the pair of reading inlet rollers. It determines with having passed 89. In other words, in the present embodiment, the main body control unit 100 and the reading entrance sensor 66 constitute a second document position determination unit.

  If the main body control unit 100 determines that the trailing edge of the document MS has passed the reading entrance roller pair 89 (YES in S9), the upstream solenoid 111 is turned on and the iron core 111a of the upstream solenoid 111 is pulled up. Then, as shown in FIG. 10C, the reading inlet driven roller 89b moves toward the reading inlet driving roller 89a and comes into contact with the reading inlet driving roller 89a. When the iron core 111a is further pulled up from the state in which the reading inlet driven roller 89b is in contact with the reading inlet driving roller 89a, the spring 114 is compressed, and the reading inlet driven roller 89b is applied to the reading inlet driving roller 89a with a predetermined pressure. Abut. As a result, the conveying force of the reading entrance roller pair 89 returns to the original state, and the next original is conveyed with a predetermined conveying force. At this time, since the document MS has already passed through the reading entrance roller pair 89, even if the conveyance force is increased, the conveyance state of the document MS is not adversely affected. In the present embodiment, the upstream solenoid 111 is turned on at the timing when it passes the pair of reading inlet rollers 89. However, the leading edge of the next original, for example, when the conveyance of the next original MS is started, It may be a predetermined timing until the roller pair 89 is reached.

  Next, the main body control unit 100 checks whether or not the trailing edge of the document MS has passed the reading position (S11). Specifically, the main body control unit 100 starts counting the drive pulses of the reading motor 73 from the time when the registration sensor 61 detects the trailing edge of the document MS, and when the number of drive pulses reaches a predetermined value, the document controller It is determined that the rear end of the MS has passed the reading position. That is, in the present embodiment, the main body control unit 100 and the registration sensor 61 constitute a fourth document position determination unit.

  If the main body control unit 100 determines that the trailing edge of the document MS has passed the reading position (YES in S11), the downstream solenoid 121 is turned on and the iron core 121a of the downstream solenoid 121 is pulled up. Then, as shown in FIG. 10D, the reading outlet driven roller 90b moves toward the reading outlet driving roller 90a and comes into contact with the reading outlet driving roller 90a. When the iron core 121a is further pulled up from the state in which the reading outlet driven roller 90b is in contact with the reading outlet driving roller 90a, the spring 124 is compressed and the reading outlet driven roller 90b is applied to the reading outlet driving roller 90a with a predetermined pressure. Abut (see FIG. 10E). As a result, the conveying force of the reading exit roller pair 90 returns to the original state, and the document MS whose rear end has passed the reading position is conveyed by the conveying force of the reading exit roller pair 90. At this time, since the document has already left the reading position and the reading of the image has been completed, even if the conveyance force of the reading exit roller pair 90 is increased, the image is not adversely affected. In this embodiment, the downstream solenoid 121 is turned ON at the timing when the trailing edge of the document passes the reading position. However, the reading roller pair 90 is read before the trailing edge of the document MS is separated from the conveyance belt 94. Any timing may be used as long as the transporting force of the vehicle is restored.

  Next, the main body control unit 100 checks whether or not there is a next original (S13). If there is a next original (YES in S13), the process returns to S4 to continue the process for the next original. If there is no next original (No in S13), both the upstream solenoid 111 and the downstream solenoid 121 are turned off (S14, S15), and the conveyance control is terminated.

  As described above, in the present embodiment, during the entire document conveyance control, at least while the image information of the document is being read, the conveyance force of the charged conveyance belt 94 is dominant over the document being read. When the conveying force of the reading inlet roller pair 89 and the reading outlet roller pair 90 is intentionally lowered so that the adhering state of the original to the conveying belt 94 does not affect the read image, the reading inlet roller pair 89 and the reading outlet roller Control is performed so that the conveyance force of the pair 90 is restored and the necessary conveyance force is applied to the document. Thereby, a good read image can be obtained, and stable document conveyance can be realized.

  Further, in the present embodiment, at least while reading the image information of the original, the reading inlet driven roller 89b is separated from the reading inlet driving roller 89a so that the conveying force of the reading inlet roller pair 89 with respect to the original becomes zero. At the same time, the reading outlet driven roller 90b is separated from the reading outlet driving roller 90a so that the conveying force of the reading outlet roller pair 90 with respect to the original is zero. This is due to the following reason. If there is a part where the original is slightly lifted from the surface of the conveying belt due to dust or wrinkles on the surface of the conveying belt, a slight pulling force or pushing force acts on the part of the original adsorbed to the conveying belt 94. The original may be peeled off from the conveying belt 94. Therefore, at least while the image information of the original is being read, the conveying force of the reading inlet roller pair 89 with respect to the original and the conveying force of the reading outlet roller pair 90 with respect to the original are set to 0 and are attracted to the original conveying belt 94. The pushing force and pulling force are prevented from acting on the part. As a result, even if there is a portion where the document slightly floats with respect to the surface of the conveying belt, the portion at the reading position of the document does not move away from the surface of the conveying belt while reading the image information of the document.

Further, when the paper jam or the like is detected during the document conveyance control, both the upstream solenoid 111 and the downstream solenoid 121 are turned off, and the pressure applied by the reading inlet roller pair 89 and the reading outlet roller pair 90 is both set. You may make it reduce.
FIG. 11 is a control flowchart of the document conveyance abnormality process.
First, when the document conveyance control is started, the main body control unit 100 checks whether a conveyance abnormality has occurred. Specifically, each sensor (document width sensor 65, reading entrance sensor 66, registration sensor 61, paper discharge sensor 63) arranged on the conveyance path determines whether or not the leading edge of the document has passed at a predetermined timing. A check is made and if the leading edge of the document does not pass at a predetermined timing, it is determined that a conveyance error has occurred. When a conveyance abnormality occurs, the driving of each motor is stopped and the document conveyance is stopped. Next, it is checked whether the upstream solenoid 111 and the downstream solenoid 121 are ON. When the upstream solenoid 111 and the downstream solenoid 121 are turned off, the display 101 of the operation unit 101 indicates that a conveyance abnormality has occurred, or a predetermined sound is generated by a speaker, causing a conveyance abnormality to the user. Notify you.
As described above, when a conveyance abnormality such as a paper jam is detected, both the upstream solenoid 111 and the downstream solenoid 121 are turned OFF, and the pressure applied to the original by the reading inlet roller pair 89 and the reading outlet roller pair 90 is reduced. Thereby, it is possible to easily perform a paper jam removing operation by the user.

As described above, the ADF 41 serving as the document conveying device according to the present embodiment has the conveying belt 94 disposed opposite to the platen glass 47 serving as the light transmitting member of the scanner 40 serving as the image reading device, and the document on the conveying belt 94. A charging roller 98 as an adsorbing means for adsorbing MS is provided, and the original MS is adsorbed on the conveyance belt 94 and conveyed to the reading position of the scanner 40. The ADF 41 according to the present embodiment is adjacent to the conveyance belt 94, adjacent to the conveyance belt 94, and a reading entrance roller pair 89 serving as a first document conveyance unit disposed upstream of the conveyance belt 94 in the document conveyance direction. Further, a reading exit roller pair 90 serving as a second document transporting unit disposed on the downstream side in the document transporting direction with respect to the transporting belt 94, and an upstream transport serving as a first transporting force changing unit that changes the document transporting force of the reading entrance roller pair 89. A force changing mechanism 110 and a downstream conveying force changing mechanism 120 as second conveying force changing means for changing the document conveying force of the reading exit roller pair 90 are provided. Then, the main body control unit 100 serving as a control means applies the document conveying force of the reading inlet roller pair 89 to a predetermined value between the time when the leading edge of the document reaches the conveying belt 94 and the time when the leading edge of the document reaches the reading position. The upstream conveyance force changing mechanism 110 is controlled so as to be weaker than the document conveyance force, and the document conveyance force of the reading exit roller pair 90 is set to a predetermined document conveyance force until the leading edge of the document reaches the reading exit roller pair 90. Also, the downstream conveyance is performed so that the document conveying force of the reading exit roller pair 90 is returned to a predetermined document conveying force after the trailing edge of the document has passed the reading position and until the trailing edge of the document is separated from the conveying belt 94. The force changing mechanism 120 is controlled.
By controlling in this way, the conveying force of the conveying belt becomes dominant during reading of the document image, and a speed difference occurs between the conveying belt 94 and the reading inlet roller pair 89 during reading of the document image. Even if a speed difference occurs between the conveyance belt 94 and the reading exit roller pair 90, the original adhering to the conveyance belt 94 can be prevented from peeling off from the conveyance belt. As a result, the original image can be read satisfactorily.

  In addition, according to the ADF 41 of the present embodiment, the first document position determination unit (comprising the main body control unit 100 and the registration sensor 61) has a predetermined amount of the leading edge of the document adsorbed on the surface of the conveyance belt 94 from the reading position. If it is determined that it has reached the upstream, the upstream conveying force changing mechanism 110 is controlled so as to reduce the 89 original conveying force of the reading entrance roller pair. By configuring in this way, the conveying force of the reading entrance roller pair 89 can be made weaker than a predetermined conveying force before the leading edge of the document reaches the reading position.

  Further, when the second document position determination means (consisting of the main body control unit 100 and the reading entrance sensor 66) determines that the trailing edge of the document has passed the reading entrance roller pair 89, the document transport of the reading entrance roller pair 89 is performed. The upstream conveyance force changing mechanism 110 is controlled so that the force is restored. With this configuration, the document can be transported with a predetermined transport force until the leading edge of the next document is detected by the first document position determining means. Further, even if the conveying force of the reading inlet roller pair is returned to a predetermined conveying force, the conveying force of the reading inlet roller pair does not reach the document whose image information is being read, which affects the reading of the document image. There is nothing.

  Further, when the third document position determination means (consisting of the main body control unit 100 and the registration sensor 61) determines that the leading edge of the document reaches a predetermined amount upstream from the reading exit roller pair 90, the conveyance of the reading exit roller pair 90 is performed. The downstream conveyance force changing mechanism 120 is controlled so that the force is weaker than a predetermined conveyance force. With this configuration, the conveying force of the reading exit roller pair can be made weaker than a predetermined conveying force before the leading edge of the document reaches the reading exit roller pair.

  Further, when the fourth document position determining means (comprising the main body control unit 100 and the registration sensor) determines that the trailing edge of the document has passed the reading position, the conveying force of the reading exit roller pair 90 is changed to a predetermined conveying force. The downstream conveyance force changing mechanism 120 is controlled to return. With this configuration, after the trailing edge of the document passes the reading position, the document can be conveyed by the conveying force of the reading exit roller pair. Further, since the conveying force of the reading exit roller pair is returned to a predetermined conveying force after the trailing edge of the document has passed the reading position, reading of the document image is not affected.

  Further, the upstream conveying force changing mechanism 110 is configured to change the pressure applied to the reading inlet driving roller 89a by the reading inlet driven roller 89b. By changing the pressing force, the conveying force of the reading entrance roller pair can be changed. Further, the downstream conveyance force changing mechanism 120 is configured to change the pressure applied to the reading outlet driving roller 90a by the reading outlet driven roller 90b. By changing the pressing force, the conveying force of the reading exit roller pair can be changed.

  Also, an abnormality detection means (consisting of a document detection sensor (a registration sensor 61, a paper discharge sensor, a reading entrance sensor, etc.) disposed on the conveyance path and a main body control unit 100) for detecting an abnormality in conveyance of the document is provided. When the abnormality detection unit detects an abnormality in document conveyance, the main body control unit 100 controls the upstream conveyance force changing mechanism 110 so that the pressure applied to the reading inlet driving roller 89a by the reading inlet driven roller 89b is weaker than a predetermined pressing force. The downstream conveyance force changing mechanism 120 is controlled so that the pressure applied to the reading outlet driving roller 90a by the reading outlet driven roller 90b is weaker than a predetermined pressure. As a result, when the user performs jam processing, it is possible to easily remove the document sandwiched between the reading entrance roller pair 89 and the reading exit roller pair.

  Further, the upstream conveyance force changing mechanism 110 and the downstream conveyance force changing mechanism 120 are configured to change the pressure applied to the drive roller of the driven roller using a solenoid. By using the solenoid, it is possible to change the pressure applied to the drive roller of the driven roller by ON / OFF control of the solenoid.

  Further, the document conveyance reading unit 1 as the image reading apparatus according to the present embodiment can read a document image satisfactorily by including the above-described ADF.

  Further, according to the copying machine according to the present embodiment, a good image can be copied by using the image reading apparatus described above.

1: Document transport reading unit 2: Image forming unit 40: Scanner 47: Platen glass 61: Registration sensor 63: Paper discharge sensor 66: Reading inlet sensor 73: Reading motor 89: Reading inlet roller pair 89a: Reading inlet driving roller 89b: Reading entrance driven roller 90: Reading exit roller pair 90a: Reading exit driving roller 90b: Reading exit driven roller 94: Conveying belt 98: Charging roller 100: Main body controller 110: Upstream conveying force changing mechanism 111: Upstream solenoid 120: Downstream conveying Force change mechanism 121: downstream solenoid

JP 2007-159033 A

Claims (8)

A conveyor belt disposed opposite to the translucent member of the image reading means with a predetermined distance;
An adsorbing means for adsorbing the original to the conveying belt;
In the document conveying device that adsorbs the document to the conveying belt and conveys the document to the reading position of the image reading unit ,
A driving roller that is adjacent to the conveying belt and rotates in the document conveying direction; and a driven roller that rotates in contact with the driving roller under pressure, and holds the document in a nip between the driving roller and the driven roller. A first document conveying means disposed on the upstream side in the document conveying direction with respect to the conveying belt,
A driving roller that is adjacent to the conveying belt and rotates in the document conveying direction; and a driven roller that rotates in contact with the driving roller under pressure, and holds the document in a nip between the driving roller and the driven roller. A second document conveying means disposed on the downstream side in the document conveying direction with respect to the conveying belt,
A first conveying force changing means for changing the original conveying force of the first original conveying means by changing the pressure applied to the driving roller of the driven roller of the first original conveying means;
A second conveying force changing means for changing the original conveying force of the second original conveying means by changing the pressure applied to the driving roller of the driven roller of the second original conveying means;
The first document conveying means has a document conveying force that is less than a predetermined document conveying force between the time when the leading edge of the document reaches the conveying belt and the time when the leading edge of the document reaches the reading position. While controlling the conveying force changing means, the original conveying force of the second original conveying means is made weaker than a predetermined original conveying force until the leading edge of the original reaches the second original conveying means, Second conveying force change means for returning the original conveying force of the second original conveying means to a predetermined original conveying force after the trailing edge reaches the reading position and before the trailing edge of the original is separated from the conveying belt. and control means for controlling,
An abnormality detection means for detecting an abnormality in conveyance of the document,
The control means controls the first original conveying force changing means so that the pressure applied to the driving roller of the driven roller of the first original conveying means is weakened when the abnormality detecting means detects an abnormality of the original conveying, and An original conveying apparatus, wherein the second original conveying force changing means is controlled so that the pressure applied to the driving roller of the driven roller of the second original conveying means is weakened . The document conveying device according to claim 1.
First document position determining means for determining whether or not the leading edge of the document adsorbed on the surface of the conveyor belt has reached a predetermined amount upstream from the reading position;
When the first document position determining unit determines that the leading edge of the document has reached a predetermined amount upstream from the reading position, the control unit determines that the document conveying force of the first document conveying unit is greater than the predetermined document conveying force. A document conveying apparatus that controls the first document conveying force changing means so as to weaken the power. In the document conveying device according to claim 1 or 2,
Second document position determining means for determining whether the trailing edge of the document has passed through the first document conveying means;
When the second document position determining unit determines that the trailing edge of the document has passed through the first document conveying unit, the control unit sets the document conveying force of the first document conveying unit to a predetermined document conveying force. A document conveying device, wherein the first document conveying force changing means is controlled so as to return to the initial position. In the document feeder according to any one of claims 1 to 3,
Third document position determining means for determining whether or not the leading edge of the document has reached a predetermined amount upstream from the second document conveying means;
When the third document position determining unit determines that the leading edge of the document has reached a predetermined amount upstream from the second document conveying unit, the control unit determines the document conveying force of the second document conveying unit to a predetermined value. An original conveying apparatus, wherein the second original conveying force changing means is controlled so as to be weaker than the original conveying force. In the document feeder according to any one of claims 1 to 4,
Fourth document position determining means for determining whether the trailing edge of the document has passed the reading position;
When the fourth document position determining unit determines that the trailing edge of the document has passed the reading position, the control unit is configured to return the document conveying force of the second document conveying unit to a predetermined document conveying force. An original conveying apparatus for controlling an original conveying force changing means . The document conveying device according to any one of claims 1 to 5 ,
The document conveying apparatus, wherein the first document conveying force changing means and the second document conveying force changing means are configured to change the pressure applied to the driving roller of the driven roller using a solenoid. An original conveying means for conveying an original;
In an image reading apparatus comprising image reading means for reading a document image of a document conveyed by the document conveying means,
As the document feeder, the image reading apparatus characterized by using any of the document feeder of claims 1 to 6. An image reader;
An image forming apparatus comprising: an image forming unit that forms an image based on a document image read by the image reading apparatus;
An image forming apparatus comprising the image reading apparatus according to claim 7 as the image reading apparatus.

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