JP5495105B2 - Document conveying apparatus, image reading apparatus, and image forming apparatus - Google Patents

Description

  The present invention relates to an original conveying apparatus, an image reading apparatus, and an image forming 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 light from a light source inside an image reading unit onto an image surface of a document via a translucent member while conveying the document by ADF. Then, the reflected light from the document image surface is read by the image sensor through the translucent member. 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 of Patent Document 1 adsorbs a document to a charged 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.

  In the image reading apparatus described in Patent Document 1, when the original is wrinkled or wavy, the original may not be well adsorbed on the surface of the endless belt, and there is a concern that the original may be lifted. As described above, when the document is conveyed to the reading position in a state where the document is lifted, there is a possibility that the image may be out of focus.

  Patent Document 2 describes an image reading apparatus in which a blade-like flexible member is provided upstream of a reading position in the document conveyance direction. The tip of the flexible member is brought into contact with the endless belt surface, the document is conveyed to the nip portion between the flexible member and the endless belt, and the document is pressed against the endless belt surface by the flexible member. As a result, the original can be brought into close contact with the endless belt surface, and the original can be adsorbed to the endless belt surface exactly. Therefore, out-of-focus can be suppressed.

However, there is a possibility that the document is peeled off from the endless belt while the document passes through the linear nip between the tip of the blade-like flexible member and the endless belt and is transported to the reading position. The reason will be described below.
Due to the electric field of the charged endless belt, charges having a polarity opposite to the charged polarity of the endless belt surface are collected on the endless belt side surface of the document, whereby the document is electrostatically attracted to the surface of the endless belt. However, it will be clear from experiments described later that it takes a certain amount of time until the charge on the endless belt surface of the document is sufficiently charged with the opposite polarity to the charged polarity of the endless belt surface and the attractive force of the document on the endless belt is increased. Became. In the image reading apparatus described in Patent Document 2, immediately after the original comes into contact with the conveyance belt, the linear nip between the end of the blade-like flexible member and the endless belt is removed. For this reason, immediately after passing through the linear nip, the charge on the endless belt side of the document is not sufficiently charged with the opposite polarity to the charged polarity of the endless belt surface, and the document is still attracted to the endless belt. The power is weak. As a result, when a force that causes separation from the endless belt is generated in the portion of the document that has passed through the nip portion between the flexible member and the endless belt, the portion between the exit of the nip portion of the document and the reading position is the endless belt. There is a risk of peeling off.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to convey a document that can closely adsorb the document to the transport belt and can prevent the document from peeling from the transport belt. An apparatus, an image reading apparatus, and an image forming apparatus are provided.

In order to achieve the above object, the invention of claim 1 is characterized in that a conveyor belt stretched around a plurality of stretch rollers and disposed opposite to the light transmitting member of the image reading means with a predetermined distance, Charging means for charging the conveyance belt, and in a document conveyance device that conveys the document to the reading position of the image reading means by electrostatically adsorbing the document to the conveyance belt, the document on the conveyance belt is so as to abut against the said conveyor belt from the original conveying direction most upstream to a position near the reading of the document conveying region to be transported, and the pressure belt which is stretched around a plurality of stretching rollers, a plurality of stretching the pressure belt And a housing that is rotatably attached to the apparatus main body, and that rotates the housing about the upstream side in the document conveying direction from the conveying belt contacting portion of the pressure belt. Rotating hand And a contacting / separating means for contacting and separating the pressure belt with respect to the conveying belt, and when the document is not conveyed, the pressure belt is separated from the conveying belt to prevent the document from entering the conveying belt. And a control means for controlling the contact / separation means so that the upstream side of the pressure belt in the document conveyance direction contacts the conveyance belt, and the pressure belt is disposed from the upstream side of the conveyance belt in the document conveyance direction. The control means is configured to contact in order, and the control means contacts the contact belt so that a contact speed at which the pressure belt contacts the transport belt sequentially from the upstream side in the document transport direction is the same as the transport speed of the document. The separation means is controlled .
According to a second aspect of the present invention, there is provided a conveying belt that is stretched by a plurality of stretching rollers and is opposed to the translucent member of the image reading unit at a predetermined distance, and charging that charges the conveying belt. Means for electrostatically adsorbing the original document to the conveying belt and conveying the original document to the reading position of the image reading means. A pressure belt stretched by a plurality of stretching rollers so as to abut on the transport belt from the most upstream in the document transport direction to the vicinity of the reading position, and a contact for contacting and separating the pressure belt with respect to the transport belt A separating means, an abnormality detecting means for detecting an abnormality in conveying the original, a deforming means for deforming an original conveying area of the conveying belt, and the abnormality detecting means, when the abnormality detecting means detects a conveying abnormality, the pressure belt is moved to the conveying belt. Or Controls the moving means to be separated, is characterized in that a control means for controlling the deformation means to deform the original conveying region of the conveying belt.
According to a third aspect of the present invention , in the document feeder of the second aspect , the contacting / separating means supports a plurality of stretching rollers that stretch the pressure belt, and is rotatably attached to the apparatus main body. And a pivot means for pivoting the housing, wherein the pivot point of the housing is provided upstream of the conveying belt contact portion of the pressure belt in the document conveying direction. Is.
According to a fourth aspect of the present invention, in the document conveying device according to the third aspect , when the document is not conveyed, the pressure belt is separated from the conveying belt, and the document is synchronized with the entry of the document into the conveying belt. Control means for controlling the contact / separation means is provided so that the upstream side of the pressure belt in the document transport direction contacts the transport belt.
The invention according to claim 5 is the document conveying apparatus according to claim 4 , wherein the pressure belt is configured to contact in order from the upstream side of the conveying belt in the document conveying direction, and the control means includes the additional unit. The contact / separation means is controlled so that the contact speed of the pressure belt contacting the transport belt in order from the upstream side in the document transport direction is the same as the transport speed of the document.
According to a sixth aspect of the present invention, there is provided the document conveying device according to any one of the first to fifth aspects , wherein the document conveying path from the contact portion exit between the conveying belt and the pressure belt to the reading position is defined as the abutting position. It is characterized in that it is linear along the document conveyance direction at the part exit.
The invention according to claim 7 is the document conveying apparatus according to claim 6 , wherein the conveying belt is adjacent to the conveying belt from the exit of the contact portion between the conveying belt and the pressure belt, and is downstream of the conveying belt in the document conveying direction. The document transport path to the nip entrance of the pair of reading exit rollers positioned at the position is made linear along the document transport direction at the exit of the contact portion.
According to an eighth aspect of the present invention, there is provided the document conveying apparatus according to the second aspect, wherein the control unit deforms the document conveying area of the conveying belt in synchronization with the separation of the pressure belt from the conveying belt. The deformation means is controlled.
According to a ninth aspect of the present invention, in the document conveying device according to any one of the first to eighth aspects, the pressure belt is made of a member that is difficult to be charged.
According to a tenth aspect of the present invention, there is provided an image reading unit including a document conveying unit configured to convey a document and an image reading unit configured to read a document image of the document conveyed by the document conveying unit via a light transmitting member at a reading position. In the apparatus, the document conveying device according to any one of claims 1 to 9 is used as the document conveying means.
According to an eleventh aspect of the present invention, in the image reading apparatus according to the tenth aspect , a translucent member contacting / separating means for bringing the translucent member into and out of contact with the transport belt is provided. .
The invention of claim 12 includes 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 10 Alternatively, 11 image reading apparatuses are provided.

According to the present invention, since the document conveyed to the conveyance belt is pressed toward the conveyance belt by the pressure belt, the document can be brought into close contact with the surface of the conveyance belt, and the document can be closely attached to the surface of the conveyance belt. Can be made.
Further, the document is conveyed in a state where it is sandwiched between the pressure belt and the conveyance belt from the most upstream in the document conveyance direction in the document conveyance area where the document on the conveyance belt is sucked and conveyed to the vicinity of the reading position. Accordingly, the original is pressed toward the conveying belt by the pressure belt until the adsorbing force increases to some extent after the original is adsorbed on the conveying belt. Then, after the suction force of the document to the transport belt is increased to some extent, the document passes through the contact portion between the transport belt and the pressure belt. As a result, even if a force that causes separation from the conveyance belt is generated in the portion of the document that is adsorbed to the conveyance belt, the portion of the document that is adsorbed to the conveyance belt is prevented from being separated from the conveyance belt. Can do. As a result, it is possible to suppress the separation of the document from the surface of the conveyance belt at the reading position, and it is possible to suppress the occurrence of out-of-focus blur.

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 periphery of the 1st fixed reading part at the time of original reading. The graph which showed the relationship between the contact time to the conveyance belt of a document, and the document conveyance force of a conveyance belt. The schematic block diagram which shows the structure of a glass contacting / separating mechanism. (A) is a partially enlarged front view showing the configuration of the glass contacting / separating mechanism, and (b) is a partially enlarged right side view. The block diagram which shows the periphery of a 1st fixed reading part when platen glass is lifted upwards. FIG. 10 is a configuration diagram illustrating the periphery of a first fixed reading unit according to Modification 1; The figure explaining the contact / separation operation | movement with respect to the conveyance belt of a pressure belt. The schematic block diagram of a pressure belt contact-separation mechanism. The figure which shows the structural example which provided the pressurization member. FIG. 3 is a diagram illustrating a configuration in which a document is linearly conveyed from an exit of a contact portion between a conveyance belt and a pressure belt to a nip portion of a reading exit roller pair. FIG. 3 is a diagram illustrating a configuration example in which a pressure belt contacts in order from an upstream side of a conveyance belt in a document conveyance direction.

  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 apparatus 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 light transmitting 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 transport 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. ing. The separating and conveying unit 51 separates and feeds the original MS one by one from the bundle of originals MS set on the original placing 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 and conveying unit 54 conveys the document MS above the platen glass 47, and the first surface of the document MS is placed on the first fixed reading unit 43 disposed inside the scanner 40 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 configuration diagram showing the periphery of the first fixed reading unit.
As shown in the figure, a conveyor belt 94 stretched between three stretch rollers is opposed to a platen glass 47 serving as a translucent member with a predetermined interval. In addition, a charging roller 98 is provided as a charging unit that contacts the outer peripheral surface of the conveyor belt 94 and charges the conveyor belt 94.

  Further, a pressure belt 95 that is stretched by a plurality of stretching rollers and is in contact with the conveyance belt is provided upstream of the reading position in the document conveyance direction. The pressure belt 95 is in contact with the conveyance belt 94 from the upstream side of the conveyance belt 94 in the document conveyance direction to the vicinity of the reading position. The pressure belt 95 may be configured to be rotated by the conveyance belt 94, or may be configured such that the driving force from the reading motor 73 is transmitted to one of a plurality of rollers that stretch the pressure belt. You may comprise so that it may be rotationally driven with the driving force of 73.

  If the electrostatic attraction force of the pressure belt 95 to the conveyance belt 94 is increased, the leading edge of the document cannot enter the contact portion between the conveyance belt 94 and the pressure belt, and a paper jam occurs. . In addition, the document is damaged, such as wrinkles. Therefore, the pressure belt 95 is preferably made of a member that is difficult to be charged. By making the pressure belt difficult to charge, electrostatic adsorption of the pressure belt 95 to the transport belt 94 can be suppressed. The pressure belt 95 is preferably made of an insulator such as rubber or plastic. By using the pressure belt 95 as an insulator, charging of the pressure belt 95 can be suppressed as compared with the case where the pressure belt 95 is a conductor. Further, the suction force of the pressure belt 95 to the conveyance belt 94 may be weakened by bringing a charge removal member into contact with the surface of the pressure belt 95 and discharging the surface of the pressure belt 95.

  The document MS conveyed to the conveyance belt 94 by the reading entrance roller pair 89 is sandwiched between the charged conveyance belt 94 and the pressure belt 95, and the document is electrostatically adsorbed to the conveyance belt 94. Specifically, the surface of the conveying belt 94 is charged by the charging roller 98. When the document comes into contact with the surface of the conveyance belt 94, a charge having a polarity opposite to the charging polarity on the conveyance belt 94 is generated on the conveyance belt 94 side of the document MS due to electrostatic polarization. Electroadsorb. 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 has been transported to the stretched portion of the stretching roller at the most downstream side 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.

  FIG. 7 is a graph showing the relationship between the contact time of the original with the conveying belt 94 and the original conveying force of the conveying belt 94. The document transport force is a force when the document attracted to the transport belt 94 is pulled and the document is separated from the transport belt, and the document transport force and the suction force have an equal relationship. As can be seen from the figure, immediately after the document comes into contact with the transport belt 94, the transport force of the transport belt 94 is weak because the electrostatic attraction force of the document is weak. When the contact time of the document with the conveyance belt 94 becomes long, electrostatic polarization of the document progresses, the electrostatic attraction force to the belt of the document increases, and the document conveyance force of the conveyance belt 94 increases. Thus, it can be seen that the document conveying force of the conveying belt 94 cannot be sufficiently obtained unless the document contacts the conveying belt 94 for a certain period of time.

  For this reason, when the document is not sufficiently adsorbed on the conveyor belt 94 and the force that causes the document to be separated from the conveyor belt is generated, the document is easily separated from the conveyor belt 94. The force that causes the document to be separated from the conveyance belt 94 is generated due to the following factors. There may be a difference in speed between the reading exit roller pair 90 and the conveyor belt 94 due to speed fluctuations of the conveyor belt 94 due to eccentricity of the tension roller that stretches the conveyor belt 94. When the document is being conveyed by the conveyance belt 94 and the reading exit roller pair 90, if the speed of the conveyance belt 94 becomes higher than the speed of the reading exit roller pair 90, the document is pushed into the portion adsorbed on the conveyance belt 94. Force is generated. Due to this pushing force, the portion of the original adhering to the conveyance belt 94 tends to bend in the direction of peeling from the conveyance belt 94. As a result, a force that causes the document to be separated from the conveyance belt is generated at the adhering portion of the document with the conveyance belt, and the document is separated from the conveyance belt.

  In the present embodiment, immediately after the document comes into contact with the conveyance belt 94, the document enters the contact portion between the conveyance belt 94 and the pressure belt 95 and is pressed toward the conveyance belt 94 by the pressure belt 95. Then, the document is conveyed to the vicinity of the reading position while being pressed by the pressure belt 95 toward the conveyance belt 94. As a result, the document is conveyed while being pressed by the pressure belt 95 toward the conveyance belt 94 until the electrostatic polarization of the document is sufficiently advanced and the electrostatic adsorption force of the document to the conveyance belt 94 is increased to some extent. Then, after a sufficient attracting force is obtained, it passes through the contact portion between the pressure belt 95 and the conveyor belt 94. As a result, even if a force that causes the document to peel from the transport belt 94 is generated, the document can be prevented from being peeled from the transport belt, and the read image can be prevented from being out of focus.

  Further, in the present embodiment, the document is transported from the reading position of the transport belt 94 so that the document passes through the contact portion between the transport belt 94 and the pressure belt 95 after sufficient electrostatic attraction is obtained. The upstream side in the direction is lengthened to some extent. At this time, if the upstream portion from the reading position of the conveyor belt 94 is extended straight in parallel with the platen glass surface, the ADF 51 is enlarged in the horizontal direction. However, in the present embodiment, the portion upstream of the reading position of the conveying belt 94 from the reading direction of the document is in contact with the pressure belt 95, so that the document is positioned more than the reading position of the conveying belt 94 as shown in the figure. Even if the upstream portion in the transport direction is not linear, the document does not lift from the transport belt 94 due to curvature separation. Further, the ADF 51 can be prevented from being increased in size in the horizontal direction by curving upward a portion upstream of the reading position in the document transport area of the transport belt 94 in the document transport direction.

  Further, since the document conveyance direction at the exit of the contact portion between the pressure belt 95 and the conveyance belt 94 is parallel to the document conveyance direction by the conveyance belt 94 from the contact portion exit to the reading position, the contact portion While the document that has passed through the exit is conveyed to the reading position by the conveying belt 94, the curvature is not separated and the original is not peeled off from the conveying belt 94. Thereby, it is possible to suppress the separation of the original from the surface of the conveyance belt at the reading position, and it is possible to suppress the occurrence of out-of-focus on the read image.

  Further, the platen glass 47 is configured to be able to come into contact with and separate from the conveyance belt 94, and adheres to the surface of the platen glass 47 by bringing the surface of the platen glass 47 close to the conveyance belt 94 during the non-original reading operation. Deposits such as dust are removed by electrostatic adsorption on the conveyor belt 94.

  FIG. 8 is a schematic configuration diagram showing a configuration of a glass contacting / separating mechanism that is a translucent member contacting / separating unit that contacts and separates the platen glass 47 with respect to the conveyor belt 94. FIG. 9A is a partially enlarged front view showing the configuration of the glass contacting / separating mechanism, and FIG. 9B is a partially enlarged right side view. As shown in FIG. 8, the platen glass 47 is fixed to the frame of the fixing member 120 made of resin, and protrudes from the front support table 122 and the rear plate 123 that protrude from the front plate 121 of the scanner 40. After that, it is placed on the support table 124. As shown in FIG. 9, two long holes 124a extending in the vertical direction are formed in the side wall of the rear support base 124, and two pins 125 provided on the side surface portion of the fixing member 120 are the long holes 124a. Are loosely fitted. Thereafter, the pin 125 of the fixing member 120 moves along the long hole 124a of the support base 124, so that the platen glass 47 can move in the vertical direction as will be described later. In FIG. 9, only the rear support table 124 is shown, but the front support table 122 side has the same configuration.

  Further, as shown in FIG. 8, the first cam shaft 127 of the first cam member 126 is rotatably supported by the front side plate 121 and the front support stand 122. A first cam pulley 128 is fixed to the end portion of the first cam shaft 127. A second cam member 129 and a second cam shaft 130 are rotatably supported by the rear side plate 123 and the rear support member 124. A second cam pulley 131 is fixed to the end portion of the second cam shaft 130. Further, below the cam members 126 and 129, a drive shaft 132 that is rotatably supported by a front plate 121 and a rear plate 123 via bearings is provided. A first timing pulley 133 is fixed to the front end portion of the drive shaft 132, and a second timing pulley 134 and a driven pulley 135 are fixed to the rear end portion. A first timing belt 136 is wound around the first cam pulley 128 and the first timing pulley 133. A second timing belt 137 is wound around the second cam pulley 131 and the second timing pulley 134. A drive timing belt 138 is wound around the driven pulley 135 of the drive shaft 132, and the drive timing belt 138 is also wound around a drive pulley 139 fixed to the motor shaft 76 a of the glass vertical movement motor 76. ing.

  A glass HP sensor 69 for detecting the reference position of the platen glass 47 is provided on the front support stand 122. The reference position of the platen glass 47 is a state in which the fixing member 120 is placed on the front support base 122 and the rear support base 124, and the first cam member 126 and the second cam member 129 are separated from the fixing member 120. It is the position of the state.

  During the document image reading operation set on the document placing table 49, the platen glass 47 disposed above the first fixed reading unit 43 is placed on the front support table 122 and the rear support table 124. At this time, the image reading sensor 43a is disposed at a position deviating from the depth of field that is a range on the optical axis that connects a clear image with the focus on the focus. That is, as shown in FIG. 10, the image reading sensor 43 a focuses on the document conveying surface that is a distance L away, but does not focus on the surface of the platen glass 47. As a result, even if a foreign object adheres to the reading position of the platen glass 47, the foreign object on the platen glass 47 is not in focus. It is read by the sensor 43a. As a result, the foreign matter on the reading position of the platen glass 47 appears as a blurred thin vertical stripe in the read image, and the vertical stripe can be made inconspicuous. Further, depending on the reading conditions, such as the density of the read image is set to be lighter than that of the original image, vertical streaks do not occur even if foreign matter adheres to the reading position of the platen glass 47. it can.

  When the reading of the document image set on the document table 49 is completed, the glass vertical movement motor 76 rotates. When the glass vertical movement motor 76 rotates, the driving force is transmitted to the drive shaft 132 via the drive timing belt 138 and the driven pulley 134. The first cam member 126 rotates from the drive shaft 132 via the first timing pulley 133, the first timing belt 136, and the first cam pulley 128. Similarly, the second cam member 129 rotates from the drive shaft 132 via the second timing pulley 134, the second timing belt 137, and the second cam pulley 131. Then, the first cam member 126 and the second cam member 129 come into contact with the fixing member 120 and lift the fixing member 120 upward. When the fixing member 120 is lifted upward by the first and second cam members 126 and 129, as shown in FIG. 9B, the pin 125 of the fixing member 120 moves along the elongated hole 124a. As a result, as indicated by a dotted line in FIGS. 8 and 9, the platen glass 47 fixed to the fixing member 120 rises a distance a and approaches the conveying belt 94. Here, the rotation angles of the first cam member 126 and the second cam member 129 are detected by a pulse count that drives the glass vertical movement motor 76 from the reference position detected by the glass HP sensor 69, and the glass vertical movement motor 76 stops. To do.

When the platen glass 47 is lifted upward by the distance a, the surface of the platen glass 47 is positioned within the suckable range H of the conveyor belt 94 as shown in FIG. At this time, H> L− (t + a), where H is the range in which the conveying belt 94 can be attracted by the charging roller 98, a is the moving distance of the platen glass 47, and t is the thickness of the platen glass. As a result, the surface of the platen glass 47 enters the adsorbable range H. The foreign matter on the platen glass 47 is dust or paper dust attached to the original MS. These are rubbed with the guide members provided in the resist portion 52 and the turn portion 53 to be frictionally charged. Further, the contact portion between the pressure belt 95 and the conveyance belt 94 is charged while being conveyed. The dust and paper dust adhering to the charged original MS drop off from the original MS and adhere to the platen glass 47 when the original MS passes through the contact portion between the pressure belt 95 and the conveying belt. Therefore, the foreign matter on the platen glass 47 is normally charged. For this reason, the foreign matter F on the platen glass 47 is electrostatically moved to the conveyance belt 94 within the adsorbable range of the conveyance belt 94 and adheres to the conveyance belt 94. Thereby, the foreign material on the platen glass 47 is removed. As a result, a blurred thin vertical streak caused by a foreign object does not occur.
Dust and paper dust adsorbed on the conveyor belt 94 are removed from the surface of the conveyor belt 94 by a cleaning means (not shown) such as a cleaning blade for cleaning the conveyor belt surface.

  Next, a modification of this embodiment will be described.

[Modification 1]
FIG. 11 is a configuration diagram illustrating the periphery of the first fixed reading unit in the image reading apparatus according to the first modification.
As shown in FIG. 12, the image reading apparatus according to the first modification is configured such that the pressure belt 95 can be brought into contact with and separated from the conveyance belt 94.

FIG. 13 is a schematic configuration diagram of a pressure belt contacting / separating mechanism that is a contacting / separating unit that contacts and separates the pressure belt 95 with respect to the conveying belt 94.
The belt contact / separation mechanism rotatably supports a plurality of rollers that stretch the pressure belt 95, and is a housing 112 that is rotatably supported by the casing of the ADF, and is a rotating means that rotates the housing 112. A belt contact / separation motor 110 is included.
The housing 112 is provided with a support shaft 112 a that is coaxial with the stretching roller 95 a that is positioned at the most upstream in the document conveying direction among the plurality of rollers that stretch the pressure belt 95. The support shaft 112a is rotatably supported by the ADF casing. A timing belt 111 is wound around the support shaft 112a and the belt contact / separation motor 110. The housing 112 is provided with a filler member (not shown). When the pressure belt 95 is in the separated position, a sensor (not shown) detects the filler member.

  As shown in FIG. 11, the tension roller 95a of the pressure belt located in the uppermost stream in the document conveying direction is located upstream of the conveying belt 94 in the document conveying direction. The tension roller 95 a is in contact with the entrance roller 99 via the pressure belt 95.

  At the time of non-document reading, the pressure belt 95 is separated from the transport belt 94 as shown by the solid line in FIG. Since the pivot point of rotation of the housing 112 is on the upstream side of the conveyance belt 94 in the document conveyance direction, the pressure belt 95 is completely separated from the conveyance belt 94 when the pressure belt 95 is in the separation position. .

  Document reading is started, and the upstream side of the pressure belt 95 in the document conveyance direction is brought into contact with the conveyance belt 94 in synchronization with the leading edge of the document entering the conveyance belt 94. Specifically, the main body control unit 100 serving as a control unit counts the driving pulse of the reading motor 73 when the registration sensor 61 detects the leading edge of the original, and when the driving pulse reaches a predetermined value, the main body control unit 100 controls the belt contact / separation motor 110. Driven to rotate the housing 112 counterclockwise. As a result, the pressure belt 95 comes into contact with the tension region between the most upstream tension roller 94 a and the middle tension roller 94 b of the conveyance belt 94. Then, the housing 112 is further rotated counterclockwise, and the pressure belt stretching roller 95c on the most downstream side in the document transport direction is added before the leading edge of the document reaches the stretching portion of the intermediate stretching roller 94b. It is brought into contact with the conveying belt 94 through the pressure belt 95. When the pressure belt stretching roller 95c comes into contact with the conveyor belt 94 via the pressure belt 95, the driving of the belt contact / separation motor 110 is stopped. Specifically, when the belt contact / separation motor 110 is driven to rotate the housing 112 counterclockwise, a sensor (not shown) does not detect the filler member. When the sensor (not shown) stops detecting the filler member, it counts the drive pulses of the belt contact / separation motor 110, and when the count reaches a predetermined value, it is determined that the pressure belt 95 has reached the contact position, The drive of the belt contact / separation motor 110 is stopped.

  When the trailing edge of the document passes through the contact portion between the conveyance belt 94 and the pressure belt 95, the belt contact / separation motor 110 is rotated in the reverse direction to separate the pressure belt 95 from the conveyance belt 94. Specifically, when the registration sensor 61 detects the trailing edge of the document, the driving pulse of the reading motor 73 is counted, and when the driving pulse reaches a predetermined value, the belt contact / separation motor 110 starts to rotate backward. Then, the housing 112 rotates clockwise, and a sensor (not shown) detects a filler member (not shown). When a sensor (not shown) detects a filler member (not shown), it is determined that the pressure belt 95 has reached the separation position, and the driving of the belt contact / separation motor 110 is stopped. The drive pulses of the belt contact / separation motor 110 are counted, and when the count reaches a predetermined value, it may be determined that the pressure belt 95 has reached the separation position. In this case, there is a merit that a filler member and a sensor are not required and the number of parts can be reduced and the cost can be suppressed. However, when the suction force of the pressure belt 95 to the transport belt 94 is increased, the belt contact / separation motor is provided. There is a demerit that 110 step-out occurs and correct position control may not be performed. Therefore, when the drive pulse of the belt contact / separation motor 110 is counted and it is determined that the pressure belt 95 has reached the separation position when the count reaches a predetermined value, the pressure belt 95 is added as a member that is difficult to be charged. It is preferable that the suction force of the pressure belt 95 to the conveyance belt 94 is suppressed.

  As described above, when the leading edge of the document enters the conveyor belt 94, the pressure belt 95 is brought into contact with the conveyor belt 94, and the trailing edge of the document is a contact portion between the conveyor belt 94 and the pressure belt 95. If the pressure belt 95 comes off, the pressure belt 95 can be brought into contact with the conveyance belt 94 only when necessary by controlling the pressure belt 95 to be separated from the conveyance belt 94. As a result, the pressure belt 95 can be prevented from adsorbing to the conveyance belt 94, and the leading edge of the document can easily enter the contact portion between the pressure belt 95 and the conveyance belt 94. Thereby, conveyance failure can be suppressed.

  Further, in the above description, the pressure belt 95 first contacts the conveyance belt 94 from the upstream side in the document conveyance direction to a certain degree of downstream. However, as shown in FIG. You may make it the structure which contact | abuts to the conveyance belt 94 in order. In this case, the belt contact / separation motor 110 is controlled so that the contact speed at which the pressure belt 95 contacts the transport belt 94 in order from the upstream side in the document transport direction becomes the same as the document transport speed. As a result, the document is conveyed in such a manner that the leading edge of the document conveyed by being attracted to the conveyance belt is sequentially pressed by the pressure belt. As a result, it is possible to suppress the leading edge of the document from being conveyed away from the pressure belt, and to suppress damage to the leading edge of the document.

  In addition, when a part of the document is nipped and conveyed between the pressure belt 95 and the conveyance belt 94 and a paper jam occurs, control is performed to move the pressure belt 95 to the separation position. Is preferred. Specifically, the main body control unit 100 monitors whether or not the leading edge of the document has passed the paper discharge sensor 63 at a predetermined timing after the registration sensor 61 detects the leading edge of the document. When the leading edge of the document does not pass at a predetermined timing, the main body control unit 100 detects that a conveyance abnormality has occurred. That is, the registration sensor 61, the paper discharge sensor 63, and the main body control unit 100 constitute an abnormality detection unit. When the main body control unit 100 detects a conveyance abnormality, the conveyance of the document is stopped. At this time, since the pressure belt 95 is in contact with the conveyance belt 94, the belt contact / separation motor 110 is reversely rotated to separate the pressure belt 95 from the conveyance belt 94. Next, the main body control unit 100 notifies the user by, for example, displaying that a conveyance failure has occurred on the display unit of the operation unit 101.

  Thus, when a conveyance failure occurs, the original can be easily removed by separating the pressure belt 95 from the conveyance belt 94.

  Further, when a conveyance abnormality occurs, the document is attracted to the conveyance belt 94, and the document may be difficult to peel off from the conveyance belt 94. For this reason, as shown in FIG. 14, a pressurizing member 113 serving as a deformation means for deforming the document conveyance area of the conveyance belt 94 may be provided. The pressing member 113 is supported so as to be movable in the vertical direction with respect to the conveyor belt surface. When a conveyance abnormality occurs, the pressure member 113 is moved to the document conveyance area side of the conveyance belt 94 in synchronization with the separation operation of the pressure belt 95. Then, the pressure member 113 comes into contact with the back surface of the conveyor belt 94 and moves the conveyor belt downward. As a result, the document conveying area of the conveying belt 94 parallel to the surface of the platen glass 47 is deformed as shown by the solid line in the figure. Then, the leading edge of the document adsorbed on the conveyance belt 94 is peeled off from the conveyance belt 94 by the curvature separation. As described above, when the leading end portion of the document is peeled off, it is easy to remove the document attracted to the conveyance belt 94, and the jam processing can be easily performed. Note that when the leading end portion of the document passes through the reading exit roller pair 90 and the trailing end portion of the document is attracted to the conveyance belt 94, the pressure belt 113 conveys the document on the conveyance belt 94. When the shape of the area is changed, the trailing edge of the document is peeled off from the conveyance belt 94.

  Further, as shown in FIG. 15, it is preferable that the original is linearly conveyed from the contact portion exit between the conveyance belt and the pressure belt to the nip portion of the reading exit roller pair 90. As a result, the orientation of the document does not change from a straight line while the document is conveyed to the nip of the reading exit roller pair 90, and no force for separating the document from the conveyance belt 94 occurs due to the rigidity of the document. For this reason, it is possible to suppress the original from being peeled from the conveyance belt 94. In particular, when a thick paper document having a large rigidity is transported, the force that separates the document from the transport belt 94 when the orientation of the document changes from a straight line increases. It is preferable that the original is conveyed linearly to the nip.

  As described above, the ADF 41 serving as the document conveying device according to the present embodiment is stretched between a plurality of stretching rollers and disposed opposite to the platen glass 47 serving as a light-transmitting member with a predetermined distance. A charging roller 98 as charging means for charging 94 is provided, and the document is electrostatically adsorbed on the conveyance belt 94 and conveyed to the reading position. The ADF 41 according to the present embodiment stretches a plurality of stretching rollers so as to abut on the conveyance belt 94 from the most upstream in the document conveyance direction of the document conveyance region where the document on the conveyance belt 94 is sucked and conveyed to the vicinity of the reading position. A pressure belt 95 is provided. As a result, the original comes out of the contact portion between the pressure belt 95 and the conveyance belt 94 after the suction force to the conveyance belt 94 is increased. As a result, even if a force that causes separation from the conveyance belt 94 occurs in the portion of the document that is adsorbed to the conveyance belt 94, the portion of the document that is adsorbed to the conveyance belt 94 is separated from the conveyance belt 94. Can be suppressed. As a result, it is possible to suppress the occurrence of out of focus in the read image.

  Further, the document conveyance path from the contact portion exit between the conveyance belt 94 and the pressure belt 95 to the reading position is made linear along the document conveyance direction at the contact portion exit. Thus, the document that has passed through the exit of the contact portion between the transport belt 94 and the pressure belt 95 is transported straight to the reading position along the document transport direction at the exit of the contact portion. During the conveyance to the reading position, it is possible to prevent the original from being separated from the conveyance belt due to the curvature separation.

  In particular, as shown in FIG. 15, a pair of reading outlet rollers 90 adjacent to the conveyance belt 94 from the exit of the contact portion between the conveyance belt 94 and the pressure belt 95 and positioned downstream of the conveyance belt 94 in the document conveyance direction. By making the document conveyance path to the nip entrance straight along the document conveyance direction at the contact portion exit, it is possible to prevent the document from being separated from the conveyance belt due to curvature separation.

  Further, according to the first modification, the pressure belt 95 is provided as a contact / separation mechanism for contacting / separating the pressure belt 95 with respect to the transport belt 94. Therefore, the pressure belt 95 is attached to the transport belt 94 as follows. Can be prevented from adsorbing to the conveyor belt 94. That is, when the document is not transported, the pressure belt 95 is separated from the transport belt 94, and the document is controlled so that the pressure belt 95 contacts the transport belt 94 in synchronization with the entry of the document into the transport belt 94. By controlling in this way, the pressure belt 95 comes into contact with the conveyance belt 94 only when necessary, so that the pressure belt 95 is always in comparison with the belt in which the pressure belt 95 is in contact with the conveyance belt 94. 95 can be prevented from being charged. As a result, it is possible to suppress the pressure belt 95 from being adsorbed to the transport belt 94. By suppressing the pressure belt 95 from adsorbing to the conveyance belt 94, it is possible to prevent the document from entering the nip portion between the pressure belt 95 and the conveyance belt 94 and to prevent a paper jam. .

  The pressure belt contacting / separating mechanism supports a plurality of stretching rollers that stretch the pressure belt 95 and is movably attached to the ADF 41, and a belt that is a rotating unit that rotates the housing 112. A contact / separation motor 110 is provided. Further, the pivot point of the housing 112 is provided on the upstream side in the document conveying direction with respect to the conveying belt 94 contact portion of the pressure belt 95. As described above, since the pivot point is located on the upstream side of the conveyance belt 94 of the pressure belt 95 in the document conveyance direction, the pressure belt 95 is completely removed from the conveyance belt 94 only by rotating the housing 112. Can be separated.

  Further, as shown in FIG. 16, the pressure belt 95 is configured to sequentially contact the upstream side of the conveyance belt 94 in the document conveyance direction, and contacts the conveyance belt 94 sequentially from the upstream side of the pressure belt 95 in the document conveyance direction. The pressure belt contacting / separating mechanism is controlled so that the contact speed is the same as the document transport speed. By controlling in this way, it is possible to suppress the leading edge of the document adsorbed on the conveying belt 94 from being pushed away from the pressure belt 95 that is in contact with the conveying belt 94 and to damage the leading edge of the document. Can be suppressed.

  In addition, when an abnormality detection unit (consisting of a registration sensor, a paper discharge sensor, a main body control unit, and the like) that detects a document conveyance abnormality detects the conveyance abnormality, the pressure belt 95 is separated from the conveyance belt 94. As a result, when the user performs jam processing, the original adhering to the conveyance belt 94 can be easily removed.

  Further, as shown in FIG. 14, a pressing member 113 is provided as a deforming means for deforming the document conveying area of the conveying belt 94. When the abnormality detecting means detects a conveying abnormality, the document conveying area of the conveying belt 94 is deformed. . By deforming the shape of the document conveyance area of the conveyance belt by the pressure member 113, the document adsorbed on the conveyance belt 94 is separated from the conveyance belt by the curvature separation. As a result, when the user performs jam processing, the original adhering to the conveyance belt 94 can be easily removed.

  In addition, it is preferable to deform the document conveyance area of the conveyance belt 94 in synchronization with the separation of the pressure belt 95 from the conveyance belt 94. Accordingly, the waiting time for the jam processing can be shortened as compared with the case where the document conveying area of the conveying belt 94 is deformed after the separation operation of the pressure belt 95 from the conveying belt 94 is completed. it can.

  Further, by making the pressure belt 95 a member that is difficult to be charged, it is possible to suppress the pressure belt 95 from being electrostatically attracted to the transport belt.

  In addition, the document conveyance reading unit 1 as the image reading apparatus according to the present embodiment includes the above-described ADF 41, so that the document image can be read satisfactorily.

  Further, the document conveying / reading unit 1 of the present embodiment is provided with a glass contacting / separating mechanism as a light transmitting member contacting / separating means for bringing the platen glass 47 into and out of contact with the conveying belt 94. If the glass contact / separation mechanism is controlled so that the platen glass 47 is brought close to the conveyance belt at the time of non-image reading, adhering substances such as dust and paper powder adhering to the surface of the platen glass 47 are adsorbed to the charged conveyance belt, It can be removed from the platen glass 47. Thereby, it is possible to suppress the occurrence of vertical stripes in the read image.

    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 (image reading device)
40: Scanner (image reading means)
41: ADF (document feeder)
47: Platen glass (translucent member)
61: Registration sensor 63: Paper discharge sensor 89: Reading entrance roller pair 90: Reading exit roller pair 94: Conveying belt 95: Pressure belt 98: Charging roller 100: Main body control unit (control means)
110: Belt contact / separation motor (turning means)
112: Housing 113: Pressure member (deformation means)

JP 2007-159033 A JP 2008-22252 A

Claims (12)

A conveyor belt that is stretched between a plurality of stretching rollers and disposed opposite to the translucent member of the image reading means with a predetermined distance;
Charging means for charging the conveyor belt,
In the document conveying device that electrostatically attracts the document to the conveying belt and conveys the document to the reading position of the image reading unit ,
A pressure belt stretched by a plurality of stretching rollers so as to abut on the transport belt from the most upstream in the document transport direction of the document transport region to which the document on the transport belt is sucked and transported to the vicinity of the reading position ;
A housing that supports a plurality of stretching rollers that stretch the pressure belt and is rotatably attached to the apparatus main body, and an upstream side of the pressure belt in the document conveyance direction from the conveyance belt contact portion. Rotation means for rotating the housing as a fulcrum; contact / separation means for contacting / separating the pressure belt to / from the transport belt;
When the document is not transported, the pressure belt is moved away from the transport belt, and the contact is made so that the upstream side of the pressure belt in the document transport direction contacts the transport belt in synchronization with the entry of the document into the transport belt. Control means for controlling the separation means,
The pressure belt is configured to contact in order from the upstream side of the conveyance belt in the document conveyance direction,
The control means controls the contacting / separating means so that the contact speed of the pressure belt in contact with the transport belt in order from the upstream side in the document transport direction is the same as the transport speed of the document. Document transport device.   A conveyor belt that is stretched between a plurality of stretching rollers and disposed opposite to the translucent member of the image reading means with a predetermined distance;
Charging means for charging the conveyor belt,
In the document conveying device that electrostatically attracts the document to the conveying belt and conveys the document to the reading position of the image reading unit,
A pressure belt stretched by a plurality of stretching rollers so as to abut on the transport belt from the most upstream in the document transport direction of the document transport region to which the document on the transport belt is sucked and transported to the vicinity of the reading position;
Contacting / separating means for contacting / separating the pressure belt with respect to the conveying belt;
An anomaly detection means for detecting an abnormal document conveyance;
Deformation means for deforming the document conveyance area of the conveyance belt;
When the abnormality detection unit detects a conveyance abnormality, the contact / separation unit is controlled to separate the pressure belt from the conveyance belt, and the deformation unit is controlled to deform the document conveyance region of the conveyance belt. An original conveying apparatus comprising a control means. The document conveying device according to claim 2 .
The contacting / separating means includes a housing that supports a plurality of stretching rollers that stretch the pressure belt, is rotatably attached to the apparatus main body, and a rotating means that rotates the housing.
An original conveying apparatus characterized in that a pivot point of rotation of the housing is provided upstream in the original conveying direction from the conveying belt contact portion of the pressure belt. The document feeder according to claim 3 .
When the document is not transported, the pressure belt is moved away from the transport belt, and the contact is made so that the upstream side of the pressure belt in the document transport direction contacts the transport belt in synchronization with the entry of the document into the transport belt. An original conveying apparatus comprising control means for controlling the separating means. The document feeder according to claim 4 , wherein
The pressure belt is configured to contact in order from the upstream side of the conveyance belt in the document conveyance direction,
The control means controls the contacting / separating means so that the contact speed of the pressure belt in contact with the transport belt in order from the upstream side in the document transport direction is the same as the transport speed of the document. Document transport device. The document conveying device according to any one of claims 1 to 5 ,
An original conveying apparatus characterized in that an original conveying path from a contact portion exit between the conveying belt and the pressure belt to the reading position is linear along the original conveying direction at the contact portion exit. The document feeder according to claim 6 .
A document conveying path from the exit of the contact portion between the conveying belt and the pressure belt to the nip entrance of a pair of reading outlet rollers located adjacent to the conveying belt and downstream of the conveying belt in the document conveying direction, An original conveying apparatus having a linear shape along an original conveying direction at an exit of the contact portion. The document conveying device according to claim 2 .
The document conveying apparatus, wherein the control means controls the deforming means to deform the document conveying area of the conveyor belt in synchronization with the separation of the pressure belt from the conveyor belt. The document feeder according to any one of claims 1 to 8 ,
An original conveying apparatus, wherein the pressure belt is made of a member that is not easily charged. An original conveying means for conveying an original;
An image reading apparatus comprising: an image reading unit that reads a document image of a document conveyed by the document conveying unit via a light transmitting member at a reading position;
As the document feeder, the image reading apparatus characterized by using any of the document feeder of claims 1 to 9. The image reading apparatus according to claim 10 .
An image reading apparatus comprising a translucent member contacting / separating means for contacting and separating the translucent member with respect to the transport belt. 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 10 or 11 as the image reading apparatus.

Images