JP2012101883A - Sheet material transporting device, image reading device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet material transporting device which can detect that a rear end of a sheet material passes a predetermined position at timing earlier than that of a conventional device without losing the setting performance of the sheet material at a sheet material loading device, and an image reading device provided with the sheet material transporting device and an image forming device.SOLUTION: The sheet material transporting device has a belt rotation detecting mechanism 140 which is a feeding material rotation detecting section that detects whether a feeding belt 84 rotates, and when a draft is transported by a pullout roller pair 86, the drive of a feeding motor 102 is turned off. By this, the feeding belt 84 rotates in conjunction with the draft transported by the pullout roller pair 86, and when a rear end of the draft goes through a separation nip Ab, the rotation of the feeding belt 84 is stopped. Accordingly, when the belt rotation detecting mechanism 140 detects that the rotation of the feeding belt 84 is stopped, it is possible to detect that the rear end of the draft goes through the separation nip Ab.

Description

  The present invention relates to a sheet material conveying apparatus that separates and conveys sheet materials one by one from a sheet material stacking unit that stacks a plurality of sheet materials, and an image reading apparatus and an image forming apparatus provided with the sheet material conveying apparatus. Is.

  Conventionally, a document automatic as a sheet material conveying device that conveys documents one by one from a document table serving as a sheet material stacking unit on which a plurality of document materials are stacked and loaded to a reading position where a document image is read by an image reading unit A document reading device provided with a conveying device is known. In this document reading device, a pickup roller serving as a calling member applies a conveying force to a document positioned at the top of a plurality of document bundles placed on a document table, and a sheet feeding roller serving as a feeding member. It sends out toward the separation nip which is a contact portion with the separation member. The document conveyed to the separation nip by the pickup roller is separated into one sheet by the separation nip and conveyed to the reading position.

  A conventional automatic document feeder includes a trailing edge detection sensor that is a trailing edge detection unit that detects the trailing edge of a document on the downstream side in the conveyance direction with respect to the separation nip. The conveyance control of the next document (hereinafter referred to as the next document) is started with the detection of the trailing edge of the document (hereinafter referred to as the previous document). As the trailing edge detection sensor, it is detected that the trailing edge of the document has passed a predetermined position by irradiating light on the surface of the document with a reflective or transmissive photosensor to detect the presence or absence of the document.

  Today, where work efficiency is required, there is an increasing demand for improvement in productivity during continuous conveyance of documents in an automatic document feeder. In order to increase productivity in an automatic document feeder, it is required to reduce as much as possible the interval between the previous document and the next document (hereinafter referred to as “paper gap”) that are continuously conveyed.

  In order to improve productivity during continuous conveyance of a document, it is preferable that the trailing edge detection sensor be disposed in the vicinity of the separation nip so that the passage of the trailing edge of the front document can be detected as early as possible. However, the leading edge of the next original may protrude downstream in the transport direction from the separation nip. Therefore, when the trailing edge detection sensor is disposed in the vicinity of the separation nip, the leading edge of the next document protruding downstream in the transport direction from the separation nip may face the trailing edge detection sensor. As a result, the trailing edge detection sensor cannot detect the trailing edge of the front document, and the trailing edge detection sensor cannot be brought sufficiently close to the separation nip.

  Patent Document 1 and Patent Document 2 have a configuration in which a roller member that contacts the upper surface of a bundle of documents on a document table is disposed and the passage of the trailing edge of the front document is detected by detecting a change in speed of the roller member. Are listed. In such a configuration, it is possible to detect the passage of the trailing edge of the front document by detecting whether or not the document is moved in the conveyance direction. In Patent Document 1 and Patent Document 2, the trailing edge of the document can be detected before the trailing edge of the document passes through the separation nip. Therefore, since the trailing edge passes through the separation nip when a predetermined time elapses after the trailing edge of the document is detected, continuous conveyance is performed by conveying the next document after the predetermined time has elapsed since the trailing edge of the document has been detected. The space between the papers can be reduced.

  However, in the configurations described in Patent Document 1 and Patent Document 2, the roller member that comes into contact with the upper surface of the document on the document table protrudes further upstream than the pickup roller. For this reason, there is a problem that the document setting property on the document table is greatly impaired and the operability is lowered, which is not practical.

  Further, the demand for detecting that the trailing edge of the front document passes through a predetermined position at the earliest possible timing is not limited to the automatic document feeder. If it is a sheet material conveying apparatus that conveys a sheet material from a sheet material accommodating unit that accommodates a plurality of sheet materials to a conveyance target position one by one, it detects that the trailing edge of the front document passes through a predetermined location at the earliest possible timing. It is required to improve productivity.

  The present invention has been made in view of the above problems, and its object is to prevent the trailing edge of the sheet material from being in a predetermined position at an earlier timing than before without impairing the setability of the sheet material in the sheet material stacking unit. It is an object of the present invention to provide a sheet material conveying device capable of detecting passing, an image reading device including the same, and an image forming device.

In order to achieve the above object, the invention according to claim 1 is a sheet material stacking unit that stacks and stacks a plurality of sheet materials, and is rotated by a drive input from a drive source and conveyed from the sheet material stacking unit. A sheet feeding member that feeds the uppermost sheet material among the sheet materials that have been formed, a separation nip formed in contact with the feeding member, and one sheet material conveyed from the sheet material stacking unit A separating member for separating the sheet material, wherein the feeding member is configured to rotate with the sheet material when driving from the driving source is cut off, and the feeding member And a feeding member rotation detecting means for detecting whether or not the sheet material is rotating, and a trailing edge detecting means for detecting the trailing edge of the sheet material based on the detection result of the feeding member rotation detecting means. It is a feature.
Further, the invention of claim 2 is the sheet material conveying apparatus according to claim 1, wherein the sheet material is conveyed by the downstream conveying member disposed downstream of the separation nip in the sheet material conveying direction. The drive source is controlled to be turned off until the rear end passes through the separation nip, and the rear end detection means detects that the feed member rotation detection means has stopped rotating the feed member. If detected, it is detected that the rear end of the sheet material has passed through the separation nip.
According to a third aspect of the present invention, in the sheet material conveying apparatus according to the first or second aspect, the separation member is input with a drive for moving the surface in a direction opposite to the surface movement direction of the feeding member in the separation nip, In a state in which the surface is in direct contact with the feeding member or via a single sheet material, the feeding member is a double feed blocking roller that rotates with the surface movement of the feeding member.
According to a fourth aspect of the present invention, in the sheet material conveying apparatus according to any one of the first to third aspects, the conveyance of the next sheet material is started based on the detection result of the trailing edge detecting means. It is.
The invention according to claim 5 is the sheet material conveying apparatus according to claim 4, wherein the sheet material stacking unit is opposed to the sheet bundle stacked on the sheet material stacking unit, and is at least the highest level of the sheet bundle stacked on the sheet material stacking unit. A calling member that calls and conveys the sheet material toward the separation nip, and contact / separation means that contacts and separates the calling member with respect to the sheet bundle loaded on the sheet material stacking unit, When at least the uppermost sheet material of the sheet bundle stacked on the sheet material stacking unit is transported to the separation nip, the contact member is controlled to separate the calling member from the sheet bundle stacked on the sheet material stacking unit. Based on the detection result of the trailing edge detecting means, the contacting / separating means causes the calling member to abut against the sheet bundle stacked on the sheet material stacking section. The one in which the features.
According to a sixth aspect of the present invention, in the sheet material conveying apparatus according to any of the first to fifth aspects, an image sensor is used as the feeding member rotation detecting means.
According to a seventh aspect of the present invention, in the sheet material conveying apparatus according to any one of the first to fifth aspects, a rotary encoder is used as the feeding member rotation detecting means.
The invention according to claim 8 is the sheet material conveying apparatus according to any one of claims 1 to 7, wherein the downstream side conveying member that conveys the sheet material is disposed downstream of the separation nip in the sheet material conveying direction. A downstream conveying member rotation detecting means for detecting whether or not the downstream conveying member rotation detecting means detects the downstream conveying member rotation detecting means when the feeding member rotation detecting means stops the rotation of the feeding member. When the means detects the rotation of the downstream conveying member, it is determined that the trailing edge of the sheet material has been detected.
Further, the invention of claim 9 is the sheet material conveying apparatus according to claim 8, wherein the downstream conveying member rotation detecting means is based on a driving signal input to a driving source for driving the downstream conveying member. The presence or absence of rotation of the downstream transport member is detected.
The invention according to claim 10 is the sheet material conveying apparatus according to claim 8 or 9, wherein the downstream conveying member rotation detecting means is a plurality of downstream conveying members disposed downstream of the separation nip. It is characterized by detecting the presence or absence of rotation of the downstream side conveyance member arranged at the most upstream in the sheet material conveyance direction.
According to an eleventh aspect of the present invention, there is provided an image reading apparatus comprising: a document conveying unit that conveys a document sheet as a sheet material; and a reading unit that reads a document image of the document sheet conveyed by the document conveying unit. The sheet material conveying device according to any one of claims 1 to 10 is used as the document conveying means.
According to a twelfth aspect of the present invention, there is provided an image forming apparatus comprising: an image reading unit; and an image forming unit that forms an image based on a document image read by the image reading unit. The image reading apparatus is provided.

  According to the present invention, since the feeding member rotates with the sheet material when the drive from the driving source is cut off, the drive input to the feeding member is cut off when the rear end of the sheet material passes through the separation nip. If so, when the trailing edge of the sheet material passes through the separation nip, the rotation of the feeding member stops. Therefore, the trailing end of the sheet material can be detected by the separation nip by detecting the rotation state of the feeding member by the feeding member rotation detecting means.

  According to the present invention, since the trailing edge of the sheet material can be detected by the separation nip, the trailing edge of the sheet material can be detected at an earlier timing than before without impairing the sheet material setting property in the sheet material stacking unit. Can be detected.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is a partial configuration diagram illustrating an enlarged part of an image forming unit in the copier. FIG. 3 is a partially enlarged view showing a part of a tandem part composed of four process units in the image forming part. FIG. 2 is a perspective view showing a scanner and an ADF of the copier. The schematic block diagram which shows the same ADF with the upper part of a scanner. The control block diagram of the whole ADF. The control part block diagram of a fixed image reading part. FIG. 10 is an enlarged explanatory view of the vicinity of an end portion on the downstream side in the conveyance direction of a document setting unit, a separation conveyance unit, and a registration unit in a conventional ADF. The schematic block diagram which shows an example of a belt rotation detection mechanism. AA sectional drawing of FIG. The schematic block diagram which shows the other example of a belt rotation detection mechanism. The sequence diagram which shows an example of the control timing of a paper feed motor and a pullout motor. The figure which shows the state by which the original was pinched | interposed into the separation nip and the nip of the pull-out roller pair. The sequence diagram which shows an example of the control timing of a paper feed motor and a pullout motor. The flowchart of a rear end detection.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter simply referred to as a copying machine 500) will be described.
First, a basic configuration of the copier 500 according to the present embodiment will be described.
FIG. 1 is a schematic configuration diagram showing a copying machine 500. The copying machine 500 includes an image forming unit 1 as image forming means, a transfer paper feeding device 40, and an image reading unit 50. The image reading unit 50 as an image reading apparatus includes a scanner 150 fixed on the image forming unit 1 and an automatic document feeder (hereinafter referred to as ADF) 51 as a sheet conveying device supported by the scanner 150. ing.

  The transfer paper feeding device 40 includes two transfer paper feed cassettes 42 arranged in multiple stages in the paper bank 41, a transfer paper feed roller 43 for feeding the transfer paper P from the transfer paper feed cassette 42, and the transferred transfer. A transfer paper separation roller 45 is provided for separating the paper P and supplying it to the transfer paper feed path 44. In addition, the main body side transfer paper feed path 37 as a transport path of the image forming unit 1 also includes a plurality of transport rollers 47 for transporting the transfer paper P as a sheet-like member. Then, the transfer paper P in the transfer paper feed cassette 42 is fed into the main body side transfer paper feed path 37 in the image forming unit 1.

  The image forming unit 1 includes an optical writing device 2, four process units 3 K, Y, M, and C that form black, yellow, magenta, and cyan (K, Y, M, and C) toner images, and a transfer unit 24. , A paper transport unit 28, a registration roller pair 33, a fixing device 34, a switchback device 36, a main body side transfer paper feed path 37, and the like. Then, a light source such as a laser diode or LED (not shown) disposed in the optical writing device 2 is driven to irradiate the four drum-shaped photosensitive members 4K, Y, M, and C with the laser light L. . By this irradiation, electrostatic latent images are formed on the surfaces of the photoreceptors 4K, Y, M, and C, and the latent images are developed into toner images via a predetermined development process.

  FIG. 2 is an enlarged partial configuration diagram illustrating a part of the internal configuration of the image forming unit 1. FIG. 3 is a partially enlarged view showing a part of a tandem part composed of four process units 3K, Y, M, and C. The four process units 3K, Y, M, and C have substantially the same configuration except that the colors of the toners to be used are different. Therefore, the subscripts K, Y, M, and C attached to the respective reference numerals in FIG. Is omitted.

  The process units 3K, Y, M, and C support the photoconductor 4 and various devices disposed around it as a single unit on a common support, and image forming of the copying machine 500 main body. It can be attached to and detached from the part 1. One process unit 3 includes a charging device 5, a developing device 6, a drum cleaning device 15, a charge removal lamp 22, and the like around the photoconductor 4. The copying machine 500 has a so-called tandem type configuration in which four process units 3K, Y, M, and C are arranged so as to face an intermediate transfer belt 25 described later along the endless movement direction. Yes.

  As the photoreceptor 4, a drum-shaped member is used in which a photosensitive layer is formed by applying a photosensitive organic photosensitive material to a base tube made of aluminum or the like. However, an endless belt may be used.

  The developing device 6 develops the latent image using a two-component developer containing a magnetic carrier and a nonmagnetic toner (not shown). In order to transfer the toner in the two-component developer carried on the developing sleeve 12 to the photosensitive member 4, the agitating unit 7 that conveys the two-component developer accommodated in the inside and supplies the developing sleeve 12 with stirring. Development section 11.

  The stirring unit 7 is provided at a position lower than the developing unit 11, and includes two conveying screws 8 arranged in parallel to each other, a partition plate provided between the two conveying screws 8, and the developing case 9. A toner density sensor 10 provided on the bottom surface is provided.

  The developing unit 11 includes a developing sleeve 12 that faces the photosensitive member 4 through the opening of the developing case 9, a magnet roller 13 that is non-rotatably provided inside the developing sleeve 12, a doctor blade 14 that approaches the developing sleeve 12, and the like. ing. The developing sleeve 12 has a non-magnetic rotatable cylindrical shape. The magnet roller 13 has a plurality of magnetic poles that are sequentially arranged from the position facing the doctor blade 14 toward the rotation direction of the developing sleeve 12. Each of these magnetic poles applies a magnetic force to the two-component developer on the developing sleeve 12 at a predetermined position in the rotational direction. As a result, the two-component developer sent from the stirring unit 7 is attracted and carried on the surface of the developing sleeve 12 and a magnetic brush is formed on the surface of the developing sleeve 12 along the lines of magnetic force.

  The magnetic brush is regulated to an appropriate layer thickness when passing through the position facing the doctor blade 14 as the developing sleeve 12 rotates, and then conveyed to the developing region facing the photoconductor 4. Then, the toner is transferred onto the electrostatic latent image by the potential difference between the developing bias applied to the developing sleeve 12 and the electrostatic latent image on the photosensitive member 4, thereby contributing to development. Further, the two-component developer that forms a magnetic brush and is carried by the developing sleeve 12 and passes through the developing region returns to the developing unit 11 again as the developing sleeve 12 rotates, and is formed between the magnetic poles of the magnet roller 13. After being separated from the sleeve surface due to the influence of the repulsive magnetic field, the magnetic field is returned to the stirring unit 7. An appropriate amount of toner is supplied to the two-component developer in the stirring unit 7 based on the detection result of the toner density sensor 10. As the developing device 6, a device using a one-component developer not containing a magnetic carrier may be adopted instead of a device using a two-component developer.

  As the drum cleaning device 15, a system in which the cleaning blade 16 made of an elastic body is pressed against the photoconductor 4 is used, but another system may be used. In order to improve the cleaning property, this example employs a system having a contact conductive fur brush 17 whose outer peripheral surface is in contact with the photosensitive member 4 so as to be rotatable in the direction of the arrow in the figure. The fur brush 17 also serves to apply the lubricant to the surface of the photosensitive member 4 while scraping the lubricant from a solid lubricant (not shown) into a fine powder. A metal electric field roller 18 for applying a bias to the fur brush 17 is rotatably provided in the direction of the arrow in the figure, and the tip of the scraper 19 is pressed against it. The toner attached to the fur brush 17 is transferred to the electric field roller 18 to which a bias is applied while rotating in contact with the fur brush 17 in the counter direction. Then, after being scraped from the electric field roller 18 by the scraper 19, it falls onto the recovery screw 20. The collection screw 20 conveys the collected toner toward the end of the drum cleaning device 15 in the direction orthogonal to the drawing surface, and delivers it to the external recycling conveyance device 21. The recycle conveyance device 21 sends the collected toner that has been delivered to the developing device 6 for recycling.

  The neutralization lamp 22 neutralizes the surface of the photoreceptor 4 by light irradiation. The surface of the photoreceptor 4 that has been neutralized is uniformly charged by the charging device 5 and then subjected to optical writing processing by the optical writing device 2. In the copying machine 500, the charging device 5 is a device in which a charging roller to which a charging bias is applied is rotated while being in contact with the photoconductor 4, but a scorotron that performs a charging process on the photoconductor 4 in a non-contact manner. A charger or the like may be used.

  In FIG. 2 described above, K, Y, M, and C toner images are formed on the photoreceptors 4K, Y, M, and C of the four process units 3K, Y, M, and C by the processes described above. Is done.

  A transfer unit 24 is disposed below the four process units 3K, Y, M, and C. The transfer unit 24 moves the intermediate transfer belt 25 stretched by a plurality of rollers endlessly in the clockwise direction in the drawing while contacting the photoreceptors 4K, Y, M, and C. As a result, primary transfer nips for K, Y, M, and C in which the photoreceptors 4K, Y, M, and C contact the intermediate transfer belt 25 are formed. In the vicinity of the primary transfer nips for K, Y, M, and C, the intermediate transfer belt 25 is transferred to the photoreceptors 4K, Y, M, and C by primary transfer rollers 26K, Y, M, and C disposed inside the belt loop. It is pushing toward. A primary transfer bias is applied to the primary transfer rollers 26K, Y, M, and C by a power source (not shown). As a result, a primary transfer electric field for electrostatically moving the toner images on the photoreceptors 4K, Y, M, and C toward the intermediate transfer belt 25 is formed in the primary transfer nips for K, Y, M, and C. Yes. In the drawing, a toner image is sequentially formed at each primary transfer nip on the front surface of the intermediate transfer belt 25 that sequentially passes through the primary transfer nips for K, Y, M, and C along with the endless movement in the clockwise direction. Overlaid and primary transferred. By this primary transfer of superposition, a four-color superposed toner image (hereinafter referred to as a four-color toner image) is formed on the front surface of the intermediate transfer belt 25.

  Below the transfer unit 24 in the figure, a paper transport unit 28 is provided between the drive roller 30 and the secondary transfer roller 31 to endlessly move the endless paper transport belt 29. The intermediate transfer belt 25 and the paper transport belt 29 are sandwiched between the secondary transfer roller 31 and the lower stretching roller 27 of the transfer unit 24. As a result, a secondary transfer nip is formed in which the front surface of the intermediate transfer belt 25 and the front surface of the paper transport belt 29 abut. A secondary transfer bias is applied to the secondary transfer roller 31 by a power source (not shown). On the other hand, the lower stretching roller 27 of the transfer unit 24 is grounded. Thereby, a secondary transfer electric field is formed in the secondary transfer nip.

  A registration roller pair 33 is disposed on the right side of the secondary transfer nip in the drawing. A registration roller sensor (not shown) is disposed near the entrance of the registration nip of the registration roller pair 33. The transfer paper P conveyed from the transfer paper feeding device 40 toward the registration roller pair 33 is temporarily stopped after a predetermined time when the leading edge of the transfer paper P is detected by a registration roller sensor (not shown). The tip is brought into contact with the resist nip of the roller pair 33. As a result, the posture of the transfer paper P is corrected, and preparations for synchronization with image formation are completed.

  When the prior application of the transfer paper P hits the registration nip, the registration roller pair 33 resumes roller rotation driving at a timing at which the transfer paper P can be synchronized with the four-color toner image on the intermediate transfer belt 25, and the transfer paper P To the secondary transfer nip. In the secondary transfer nip, the four-color toner images on the intermediate transfer belt 25 are collectively transferred to the transfer paper P due to the influence of the secondary transfer electric field and the nip pressure, and combined with the white color of the transfer paper P, a full color image is formed. The transfer paper P that has passed through the secondary transfer nip is separated from the intermediate transfer belt 25 and is conveyed to the fixing device 34 along with its endless movement while being held on the front surface of the paper conveyance belt 29.

  The transfer residual toner that has not been transferred to the transfer paper P at the secondary transfer nip is attached to the front surface of the intermediate transfer belt 25 that has passed through the secondary transfer nip. The transfer residual toner is scraped and removed by the belt cleaning device 32 in which the cleaning member contacts the intermediate transfer belt 25.

  The transfer paper P conveyed to the fixing device 34 is fixed to a full-color image by pressurization or heating in the fixing device 34, and then sent from the fixing device 34 to the paper discharge roller pair 35. The paper is discharged to a paper discharge tray 501.

  In FIG. 1 described above, a switchback device 36 that is a transfer paper reversing device is disposed under the paper transport unit 28 and the fixing device 34. As a result, when performing duplex printing, the transfer path of the transfer sheet P that has undergone image fixing processing on one side is switched to the switchback device 36 side by the switching claw, where the transfer sheet P is reversed and re-secondary. Enter the transfer / transfer nip. Then, the other side of the transfer paper P is subjected to image secondary transfer processing and fixing processing, and then discharged onto a paper discharge tray 501.

  The image reading unit 50 including the scanner 150 fixed on the image forming unit 1 and the ADF 51 fixed on the image forming unit 1 includes two fixed reading units and a moving reading unit 152 described later. The movable reading unit 152 is disposed directly below the second contact glass 155 fixed to the upper wall of the casing of the scanner 150 so as to come into contact with the document MS, and shows an optical system including a light source, a reflection mirror, and the like. It can be moved in the left-right direction. Then, in the process of moving the optical system from the left side to the right side in the figure, after the light emitted from the light source is reflected by the lower surface of the document MS placed on the second contact glass 155, a plurality of reflecting mirrors are Then, the light is received by the image reading sensor 153 fixed to the scanner 150.

  On the other hand, the image reading unit 50 includes, as fixed reading units, a first fixed reading unit 151 disposed in the scanner 150 and a second fixed reading unit 95 described later disposed in the ADF 51. . A first fixed reading unit 151 including a light source, a reflection mirror, an image reading sensor such as a CCD, and the like is disposed directly below a first contact glass 154 fixed to the upper wall of the casing of the scanner 150 so as to contact the document MS. ing. Then, when the document MS conveyed by the ADF 51 passes over the first contact glass 154, image reading is performed via a plurality of reflecting mirrors while sequentially reflecting the light emitted from the light source on the first surface of the document MS. The sensor 153 receives light. Accordingly, the first surface of the document MS is scanned without moving the optical system including the light source and the reflection mirror. The second fixed reading unit 95 scans the second surface of the document MS after passing through the first fixed reading unit 151.

An ADF 51 disposed on the scanner 150 includes a document placing table 53 for placing a document MS before reading on a main body cover 52, a document transporting unit 54 for transporting a document MS as a sheet material, and a reading. A document stacking table 55 for stacking the subsequent document MS is held.
FIG. 4 is a perspective explanatory view of the image reading unit 50. As shown in FIG. 4, it is supported by a hinge 159 fixed to the scanner 150 so as to be swingable in the vertical direction. Then, by swinging, it moves like an open / close door, and the first contact glass 154 and the second contact glass 155 on the upper surface of the scanner 150 are exposed in the opened state. 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 therefore cannot be transported by the ADF 51. Therefore, in the case of a single-sided original, the ADF 51 is opened as shown in FIG. close up. Then, the image of the page is read by the moving reading unit 152 shown in FIG.

  On the other hand, in the case of a document stack in which a plurality of independent documents MS are simply stacked, the documents MS are automatically conveyed one by one by the ADF 51 while the first fixed reading unit 151 in the scanner 150 and the second fixed document in the ADF 51 are used. The fixed reading unit 95 can sequentially read. In this case, after the original bundle is set on the original placement table 53, the copy start button 158 of the operation unit 108 is pressed. Then, the ADF 51 sends the document MS of the bundle of documents placed on the document placement table 53 in order from the top into the document conveyance unit 54 and conveys the document MS toward the document stacking table 55 while inverting it. In the course of this conveyance, immediately after the original MS is reversed, it passes through the first fixed reading unit 151 of the scanner 150. At this time, the image on the first surface of the document MS is read by the first fixed reading unit 151 of the scanner 150.

Next, the ADF 51 will be described.
FIG. 5 is an enlarged configuration diagram showing the main configuration of the ADF 51 together with the upper portion of the scanner 150. The ADF 51 includes a document setting unit A, a separation conveyance unit B, a registration unit C, a turn unit D, a first reading conveyance unit E, a second reading conveyance unit F, a paper discharge unit G, a stack unit H, and the like. The document conveying portion 54 of the ADF 51 according to the present embodiment is a portion that constitutes a path through which the document MS is conveyed from the detection position by the butting sensor 72 sensor on the downstream side of the separation conveying portion B to the reading entrance roller pair 90. .
Further, the ADF 51 rotates about the cover rotation center 145a with respect to the apparatus main body, thereby opening and closing the sheet feeding path to the middle of the separation conveyance unit B, the registration unit C, and the turn unit D. Is provided.

  The document setting unit A includes a document placement table 53 on which a bundle of documents MS is set so that the first surface is upward. The separation conveyance unit B separates and feeds the originals MS one by one from the set of originals MS set. The registration unit C temporarily abuts on the fed document MS to align the document MS, and pulls out and transports the document MS after alignment. The turn portion D has a curved conveyance portion that is curved in a C shape, and the document MS is turned upside down while being folded in the curved conveyance portion, so that the first surface of the original MS is directed downward. . The first reading and conveying unit E conveys the document MS on the first contact glass 154, while the document MS is transferred from the lower side of the first contact glass 154 to the first fixed reading unit 151 disposed in the scanner 150. The first side is read. The second reading conveyance unit F causes the second fixed reading unit 95 to read the second surface of the document MS while conveying the document MS by a second reading roller 96 disposed below the second fixed reading unit 95. It is. The paper discharge unit G discharges the original MS from which both-side images are read toward the stack unit H. Further, the stack unit H stacks and holds the document MS after the reading is completed on the document stacking table 55.

  FIG. 6 is a control block diagram of the entire ADF 51. The control unit of the ADF 51 includes motors 101 to 105, 113, and 114, which are driving units that drive a document conveying operation, various sensor units, and a fixed image reading unit 300 (first fixed reading unit 151 or second fixed reading unit). 95), and the controller 100 for controlling a series of operations.

  FIG. 7 is a control unit block diagram of the fixed image reading unit 300. The fixed image reading unit 300 includes a light source unit 200, a sensor chip 201, an image processing unit 204, a frame memory 205, an output control circuit 206, and the like.

A bundle of documents MS to be read is set on the document placing table 53 in a state where the bundle is placed so that the first surface faces upward. The document placing table 53 supports a leading end of the document and can move in the directions of arrows a and b in FIG. 1 according to the thickness of the bundle of documents MS, and a fixed document table that supports the document trailing end side. 53a. When the document MS is set on the document placement table 53, it is on the document placement table 53 with respect to both ends in the width direction (a direction perpendicular to the conveyance direction of the document MS and a direction perpendicular to the paper surface of FIG. 1). Each side guide (not shown) is abutted to position the document MS in the width direction.
The document MS set on the document table 53 in this manner pushes up the set filler 62 that is a lever member that is swingably disposed above the movable document table 53b. Along with this, the document set sensor 63 detects the setting of the document MS and transmits a detection signal to the controller 100. The detection signal is transmitted from the controller 100 to the main body control unit 111 of the image reading unit 50 via an interface circuit (hereinafter referred to as I / F 107).

  Further, the fixed document table 53a includes a plurality of document length sensors (57, 58a, etc.) including a reflection type photo sensor that detects the length of the document MS in the conveyance direction or an actuator type sensor that can detect even one document. 58b) is arranged. By these document length sensors, an outline of the length of the document MS in the conveyance direction is determined (a sensor arrangement capable of determining at least whether the document size is vertical or horizontal is necessary).

A pickup roller 80 is disposed above the movable document table 53b. The pickup roller 80 is rotationally driven by the driving force transmitted from the paper feed motor 102 together with the paper feed belt 84 and the reverse roller 85 constituting a separation nip as a separation unit.
The movable document table 53b is swung in the directions of arrows a and b in FIG. When the set filler 62 or the document set sensor 63 detects that the document MS is set on the document placement table 53, the controller 100 rotates the bottom plate raising motor 105 in the normal direction so that the uppermost surface of the bundled document MS is in contact with the pickup roller 80. The movable document table 53b is raised so as to come into contact.
The pickup roller 80 can be moved in the directions of arrows c and d in FIG. 5 by a cam mechanism driven by the pickup lifting / lowering motor 101. The movable document table 53b rises and is pushed by the upper surface of the document MS on the movable document table 53b and moves up in the direction of arrow c in the figure. By detecting this by the table lift sensor 59, the lift to the upper limit of the movable document table 53b is detected. As a result, the pickup raising / lowering motor 101 stops and the bottom plate raising motor 105 stops.

  A copy start button 158 is pressed from the operation unit 108, and a document feed signal is transmitted from the main body control unit 111 to the controller 100 which is a control unit of the ADF 51 via the I / F 107. As a result, the paper feed motor 102 is driven and the pickup roller 80 is driven to rotate forward to pick up several (ideally, one) originals MS on the original placement table 53. The rotation direction of the pickup roller 80 is a direction in which the uppermost document MS is conveyed to the paper feed port 48.

The document MS sent out by the pickup roller 80 enters the separating and conveying section B and is sent to a contact position with the paper feeding belt 84 as a feeding member. The paper feed belt 84 is stretched by a drive roller 82 and a driven roller 83, and is endlessly moved clockwise in FIG. 5 by the rotation of the drive roller 82 accompanying the normal rotation of the paper feed motor 102.
A reverse roller 85, which is a separating member that is driven to rotate clockwise in the drawing by the forward rotation of the paper feed motor 102 and a double feed prevention roller, is in contact with the lower tension surface of the paper feed belt 84. In the separation nip which is the contact portion, the surface of the paper feed belt 84 moves in the paper feed direction. On the other hand, the surface of the reverse roller 85 tries to move in the direction opposite to the paper feeding direction, but the drive transmission portion of the reverse roller 85 has a torque limiter (not shown), and the force toward the paper feeding direction is torque. When the torque is larger than the limiter torque, the reverse roller 85 rotates so as to move the surface in the sheet feeding direction.
The reverse roller 85 is in contact with the paper feed belt 84 at a predetermined pressure and is in direct contact with the paper feed belt 84 or in contact with the paper feed belt 84 through only one original MS. In a state where only one document MS is sandwiched in the separation nip, the sheet rotates with the paper feed belt 84 or the document MS and rotates counterclockwise in FIG. However, since the rotation force is set to be lower than the torque of the torque limiter when a plurality of originals MS are sandwiched in the separation nip, the reverse roller 85 is the clock in the figure opposite to the rotation direction. Rotate around. As a result, a moving force in the direction opposite to the feeding direction is applied to the original document MS below the uppermost position by the reverse roller 85, so that only the uppermost original MS is separated from several originals, and the double feed is performed. Is prevented.

The document MS separated into one sheet by the action of the sheet feeding belt 84 and the reverse roller 85 enters the registration unit C. Then, the document MS is further fed by the paper feed belt 84 and abutted against the pull-out roller pair 86 which is further advanced and stopped while the leading edge is detected by the butting sensor 72. The paper feed motor 102 being driven at this time is driven for a predetermined time from the detection of the tip by the abutting sensor 72 and then stopped. As a result, the document MS is fed by a predetermined distance from the position detected by the abutting sensor 72. As a result, the document MS is fed in a state where the document MS is pressed against the pull-out roller pair 86 with a predetermined amount of bending. The conveyance of the document MS by the belt 84 is stopped.
When the leading edge of the document MS is detected by the abutting sensor 72, the pickup lifting / lowering motor 101 is rotated so that the pickup roller 80 is retracted from the upper surface of the document MS and the document MS is sent only by the conveying force of the paper feed belt 84. . As a result, the leading edge of the document MS enters the nip formed by the upper and lower rollers of the pull-out roller pair 86, and leading edge alignment (skew correction) is performed.

  As described above, the pull-out roller pair 86 has a skew correction function and is a roller pair for transporting the skew-corrected document MS to the intermediate roller pair 66 after separation. One of the two rollers is driven to rotate. Further, the paper feed belt 84 and the pull-out roller pair 86 are rotationally driven so that the leading edge of the document MS conveyed to the pull-out roller pair 86 by the paper feed belt 84 is brought into contact with the pull-out roller pair 86 without skew correction. A configuration may be adopted in which the document is conveyed by the pull-out roller pair 86.

  The drive source of the pull-out roller pair 86 may be the paper feed motor 102. In such a case, when the paper feed motor 102 is rotated forward, the drive is transmitted to the pickup roller 80, the paper feed belt 84 and the reverse roller 85, and when the paper feed motor 102 is reversed, the pull-out roller pair 86 is transmitted. It is comprised so that a drive may be transmitted to. However, as in this embodiment, driving the pull-out roller pair 86 with the pull-out motor 113, which is an independent drive, makes it possible to shorten the motor start-up time and the time for the motor to improve productivity. .

  The document MS sent out by the pull-out roller pair 86 passes directly under the document width sensor 73. The document width sensor 73 is a sensor in which a plurality of paper detection sensors such as a reflection type photosensor are arranged in the document width direction (direction orthogonal to the paper surface of FIG. 5), and which paper detection sensor detects the document MS. Based on the above, the size of the document MS in the width direction is detected. The length of the document MS in the conveyance direction is from when the leading edge of the document MS is detected by the abutting sensor 72 to when the document MS is not detected by the abutting sensor 72 (the trailing edge of the document MS passes). Detect from motor pulse based on timing.

The document MS conveyed by the rotational drive of the pull-out roller pair 86 and the intermediate roller pair 66 enters the turn part D conveyed by the intermediate roller pair 66 and the reading entrance roller pair 90.
The intermediate roller pair 66 is configured such that the drive is transmitted from both the pull-out motor 113 which is a drive source of the pull-out roller pair 86 and the reading inlet motor 114 which is a driving source of the reading inlet roller pair 90. A mechanism is provided in which the rotational speed is determined by driving the motor on the side of the two motors whose rotational speed is faster.
In the ADF 51, when the document MS is conveyed from the registration unit C to the turn unit D by the rotational drive of the pull-out roller pair 86 and the intermediate roller pair 66, the conveyance speed at the registration unit C is set at the first reading conveyance unit E. The speed is set higher than the transport speed, and the processing time for feeding the document MS to the first reading transport section E is shortened. At this time, the intermediate roller pair 66 rotates using the pull-out motor 113 as a drive source.

  When the leading edge of the document MS is detected by the reading entrance sensor 67, the transportation speed of the document MS is set to the first scanning transportation before the leading edge of the document MS enters the nip formed by the upper and lower rollers of the pair of scanning entrance rollers 90. In order to make it the same speed as the conveyance speed in the part E, the pull-out motor 113 starts decelerating. At the same time, the reading inlet motor 114 and the reading motor 103 are driven forward. When the reading inlet motor 114 is driven to rotate forward, the reading inlet roller pair 90 is rotationally driven in the conveying direction, and when the reading motor 103 is driven to rotate forward, the reading outlet roller pair 92 and the second reading outlet roller pair 93 are moved in the conveying direction. To drive each. By starting the driving of the reading inlet roller pair 90 and decelerating the pull-out motor 113, the driving force is transmitted from the reading inlet motor 114 rather than the rotational speed of the intermediate roller pair 66 transmitted by the pull-out motor 113. When the rotational speed of the intermediate roller pair 66 is faster, the intermediate roller pair 66 rotates using the reading entrance motor 114 as a drive source.

When the registration sensor 65 detects the leading edge of the document MS from the turn portion D toward the first reading conveyance portion E, the controller 100 decelerates the driving of each motor over a predetermined time, thereby increasing the conveyance speed of the document MS. Decelerate over a predetermined transport distance. Then, the controller 100 controls the document MS to be temporarily stopped before the first reading position 400 by the first fixed reading unit 151 and transmits a registration stop signal to the main body control unit 111 via the I / F 107. .
Subsequently, when the controller 100 receives a reading start signal from the main body control unit 111, the conveying speed of the document MS is set to a predetermined conveying speed until the leading edge of the document MS whose registration is stopped reaches the first reading position 400. The driving of the reading inlet motor 114 and the reading motor 103 is controlled so as to rise up to As a result, the document MS is conveyed toward the first reading position 400 while the conveyance speed is increased. Then, at the timing when the leading edge of the document MS calculated based on the pulse count of the reading entrance motor 114 reaches the first reading position 400, the sub-scan of the first surface of the document MS from the controller 100 to the main body control unit 111 is performed. A gate signal indicating a direction effective image area is transmitted. This transmission is continued until the trailing edge of the document MS leaves the first reading position 400, and the first surface of the document MS is read by the first fixed reading unit 151.

The document MS that has passed through the first reading / conveying section E passes through the nip of the reading exit roller pair 92, and then the leading edge of the document MS is detected by the paper discharge sensor 61, and then passes through the second reading / conveying section F. It is conveyed to the paper discharge unit G.
When reading only one side (first side) of the document MS, it is not necessary to read the second side of the document MS by the second fixed reading unit 95. Therefore, when the leading edge of the document is detected by the paper discharge sensor 61, the forward drive of the paper discharge motor 104 is started, and the upper paper discharge roller in the drawing roller pair 94 is rotated counterclockwise in the drawing. Driven by rotation. The timing at which the trailing edge of the document MS exits the nip of the sheet discharge roller pair 94 is calculated based on the pulse count of the sheet discharge motor 104 after the leading edge of the document MS is detected by the sheet discharge sensor 61. Based on this calculation result, the driving speed of the paper discharge motor 104 is decelerated at the timing immediately before the trailing edge of the original MS comes out of the nip of the discharge roller pair 94, and the original MS is removed from the original stack base 55. Control is performed so that the paper is discharged at such a speed as not to jump out.

  On the other hand, when both sides (first side and second side) of the document MS are read, the timing from when the leading edge of the document MS is detected by the paper discharge sensor 61 until reaching the second fixed reading unit 95 is read. Calculation is performed based on the pulse count of the motor 103. At that timing, the controller 100 transmits a gate signal indicating an effective image area in the sub-scanning direction on the second surface of the document MS to the main body control unit 111. This transmission is continued until the trailing edge of the document MS exits the second reading position by the second fixed reading unit 95, and the second surface of the document MS is read by the second fixed reading unit 95.

  The second fixed reading unit 95 as a reading unit includes a contact image sensor (CIS), and for the purpose of preventing a reading vertical streak caused by a paste-like foreign material adhering to the document MS adhering to the reading surface. The reading surface is coated. Further, a second reading roller as a document supporting means for supporting the document MS from the non-reading surface side (first surface side) is located at a position facing the second fixed reading unit 95 across the conveyance path through which the document MS passes. 96 is arranged. The second reading roller 96 serves as a reference white portion for suppressing shading of the document MS at the second reading position by the second fixed reading unit 95 and acquiring shading data in the second fixed reading unit 95. Is responsible.

Next, features of the present embodiment will be described.
FIG. 8 is an enlarged explanatory view of the vicinity of the downstream end in the transport direction of the document setting section A, the separation transport section B, and the registration section C in the ADF 51 of the conventional example.
FIG. 8 shows a state at the moment when the rear end of the previous document MS1 passes through the separation nip Ab with respect to the previous document MS1 and the next document MS2 as two documents MS that are continuously conveyed.
Conventionally, as shown in FIG. 8, a trailing edge detection sensor Sn that detects the trailing edge of the document arranged at a distance d away from the separation nip Ab in the document conveying direction downstream detects the trailing edge of the document. As a result, it is detected that the trailing edge of the previous original has passed through the separation nip, and the conveyance of the next original has been started. For this reason, there is a problem in that the interval (between sheets) between the previous document and the next document is widened, resulting in poor productivity. By disposing the trailing edge detection sensor Sn in the vicinity of the separation nip, the conveyance of the next document can be started immediately after the trailing edge of the previous document passes through the separation nip. However, as shown in FIG. 8, the leading end of the next original MS2 (“MS2a” in FIG. 8) protrudes from the separation nip Ab before the rear end of the previous original MS1 passes through the separation nip Ab (from the separation nip Ab). May also be in the downstream side in the transport direction). In such a case, when the rear end detection sensor Sn is disposed in the vicinity of the separation nip Ab, the portion of the next original MS2 that protrudes from the separation nip Ab faces the rear end detection sensor Sn. As a result, if the trailing edge detection sensor Sn is disposed in the vicinity of the separation nip Ab, the trailing edge detection sensor Sn cannot detect the trailing edge of the front document MS1.

  Therefore, in the conventional ADF 51, as shown in FIG. 8, a rear end detection sensor Sn made of a transmissive or reflective photosensor is arranged at a position separated from the separation nip Ab by a predetermined distance d on the downstream side. The passage of the trailing edge of the front document MS1 was detected.

  Further, in the trailing edge detection sensor Sn composed of a transmissive or reflective photosensor, the trailing edge is detected even in the case of a document whose sensor is temporarily not detected, such as when a punch hole is formed in the document. It is necessary to perform the following control so that the detection sensor Sn does not erroneously detect that the trailing edge of the document has been detected. That is, even if the trailing edge detection sensor Sn does not detect the document, it is not determined that the trailing edge of the document has been detected immediately, and the sensor output is detected even if a predetermined time elapses after the trailing edge detection sensor Sn stops detecting the document. It is necessary to determine that the rear end detection sensor Sn has detected the rear end at the stage where it is confirmed that the state does not return to the state. Therefore, when the trailing edge detection sensor Sn composed of a transmissive or reflective photosensor is used, the conveyance of the next document is started only after a predetermined time has elapsed since the trailing edge of the previous document was detected. I can't.

  Therefore, in the present embodiment, when the previous document is being conveyed by the pull-out roller pair 86 disposed downstream of the separation nip Ab in the document conveyance direction, the paper feeding belt 84 is rotated with the previous document MS1 to supply the document. By detecting the presence or absence of rotation of the paper belt 84, it is detected that the trailing edge of the front document MS1 has passed through the separation nip Ab.

FIG. 9 is a schematic configuration diagram illustrating an example of a belt rotation detection mechanism 140 serving as a feeding member rotation detection unit that detects the presence or absence of rotation of the paper feed belt 84, and FIG. 10 is a cross-sectional view taken along line AA in FIG. is there.
As shown in FIGS. 9 and 10, the belt rotation detection mechanism 140 includes an encoder wheel 141 attached to the shaft of the driven roller 83 and a circle (not shown) provided on the circumference of the encoder wheel 141 at a predetermined interval. The reflection type photo sensor 142 that detects the reflection mark of the photo sensor and the controller 100 that receives a signal from the photo sensor 142 are configured. The reflective photosensor 142 is attached to the paper feed unit cover 145 via the sensor bracket 143. When the photo sensor 142 detects a reflection mark (not shown), an ON signal is output to the controller 100. Therefore, when the paper feeding belt 84 is rotated and the driven roller 83 is rotating, the controller 100 receives an ON-OFF signal at regular intervals from the photo sensor 142. On the other hand, when the paper feed belt 84 is stopped and the driven roller 83 is stopped, the controller 100 receives a continuous signal of ON or OFF from the photo sensor 142. As described above, the controller 100 can detect whether the paper feeding belt 84 is rotating or stopped by monitoring the signal from the photosensor 142.

  In the above description, the encoder wheel 141 is provided on the shaft of the driven roller 83, but it may be provided on the drive roller 82. Alternatively, an encoder seal may be attached to the end of the paper feed belt 84 to detect the rotation of the paper feed belt 84. Moreover, the structure which affixed the disk-shaped encoder seal to the flange of the driven roller 83 may be sufficient. In the above, a reflective photosensor is used, but a transmissive photosensor can also be used. In this case, a slit is formed at a predetermined interval on the circumference of the encoder wheel 141.

FIG. 11 is a schematic configuration diagram illustrating another example of the belt rotation detection mechanism 140 that detects the presence or absence of rotation of the paper feed belt.
The belt rotation detection mechanism 140 illustrated in FIG. 11 includes a controller 100 that receives a signal from the image sensor 146 and the image sensor 146 by disposing an image sensor 146 such as a complementary metal oxide semiconductor (CMOS) image sensor opposite to the sheet feeding belt. It consists of and. The controller 100 receives the signal from the image sensor 146 to detect whether or not the paper feed belt 84 is rotating.

Next, rear end detection by the belt rotation detection mechanism 140 will be described.
First, the trailing edge detection in the configuration in which the document MS is conveyed by the pull-out roller pair 86 without a skew correction by abutting the leading edge of the document MS conveyed to the pull-out roller pair 86 by the paper feed belt 84 against the pull-out roller pair 86. explain.
FIG. 12 is a sequence diagram illustrating an example of control timing of the paper feed motor 102 and the pull-out motor 113. FIG. 12 shows ON / OFF of the paper feed motor 102, ON / OFF of the pull-out motor 113, rotation / stop of the paper feed belt 84 (driven roller 83), and rotation / stop of the pull-out roller pair 86 from the top. The horizontal axis indicates time.

As shown in the figure, when conveyance of the document MS on the document table 53 is started, the drive of the paper feed motor 102 and the pull-out motor 113 is turned on, and the pickup roller 80, the paper feed belt 84, and the pull-out roller rotate. Then, the document MS on the document table 53 is conveyed downstream. When the abutting sensor 72 detects the leading edge of the document MS and detects that the document MS has reached the nip Ac (see FIG. 13) of the pull-out roller pair 86, it is fed at a predetermined timing to prepare for feeding the next document. The paper motor 102 is turned off. As a result, the paper feed belt 84 is turned off by the paper feed motor 102. At this time, as shown in FIG. 13, the portion of the document MS upstream in the transport direction of the document MS is in the separation nip Ab. Therefore, the paper feed belt 84 rotates with the document MS conveyed by the pull-out roller pair 86. The document is conveyed further downstream by the pull-out roller pair 86, and when the trailing edge of the document passes through the separation nip Ab, the rotation of the paper feed belt 84 that has been rotated by the document MS is stopped. Then, the signal to the controller 100 of the photo sensor 142 or the image sensor 146 changes, the controller 100 detects that the rotation of the paper feed belt 84 has stopped, and the trailing edge of the document MS has passed through the separation nip Ab. Can be detected. Therefore, the controller 100 starts feeding the next document by using a change in the signal from the photo sensor 142 or the image sensor 146 as a trigger. Specifically, the controller 100 controls the timing of driving ON of the paper feed motor 102 by using the stop of the rotation of the paper feed belt 84 as a trigger. As described above, when the rotation of the paper feed belt 84 is stopped as a trigger for starting the next document conveyance, the timing at which the trailing edge of the document passes through the separation nip Ab can be used as a trigger for starting the next document conveyance. , Can narrow the gap between paper. In addition, since the trailing edge of the document is detected by stopping the rotation of the paper feeding belt 84, the rear edge of the punch hole is detected as in the case where the optical sensor such as a photo sensor shines light on the document and directly detects the trailing edge of the document. There is no need to perform processing to prevent edge misdetection. Even if the leading edge of the next document protrudes from the separation nip Ab, the trailing edge of the document can be detected at the position of the separation nip Ab. As a result, the timing for starting the feeding of the next original can be advanced as compared with the case where the photo sensor directly detects the trailing edge of the original.
The pickup roller 80 is lowered by controlling the timing at which the pickup lift motor 101 is turned on, for example, when the abutting sensor 72 detects the leading edge of the document. Is done.

Next, a description will be given of trailing edge detection in a configuration in which the leading edge of the document MS conveyed to the pull-out roller pair 86 by the paper feed belt 84 is abutted against the pull-out roller pair 86 to correct skew.
In the configuration in which the leading edge of the document MS is abutted against the pull-out roller pair 86 and the conveyance of the document MS is stopped for skew correction, even if only the stoppage of the rotation of the paper feed belt 84 is detected, the trailing edge of the document MS However, it cannot be distinguished whether the rotation of the paper feed belt 84 has stopped after passing through the separation nip Ab, or whether the document being transported has stopped due to document abutment by skew correction. Therefore, in such a case, in addition to the presence / absence of the rotation of the paper feed belt 84, the rotation of the pull-out roller pair 86 downstream thereof is detected, so that the conveyance of the original MS is stopped or the rear end of the original is separated from the separation nip Ab. Distinguish whether or not.

FIG. 14 is a sequence diagram illustrating another example of the control timing of the paper feed motor 102 and the pull-out motor 113. FIG. 15 is a diagram illustrating a case where the document is stopped while the document is being transported and the rotation of the paper feed belt 84 is stopped. It is a flowchart of the rear end detection in the structure to perform.
FIG. 14 shows ON / OFF of the paper feed motor 102, ON / OFF of the pull-out motor 113, rotation / stop of the paper feed belt 84 (driven roller 83), and rotation / stop of the pull-out roller 86 from the top. The axis shows time.
When conveyance of the document MS on the document placement table 53 is started, the paper feed motor 102 is turned on, the pickup roller 80 and the paper feed belt 84 are driven to rotate, and the document on the document placement table 53 is conveyed downstream. The When the abutting sensor 72 detects the leading edge of the document MS and a predetermined time has elapsed, the paper feed motor 102 is turned off. At this time, the conveyance of the document is stopped, and the stop of the rotation of the sheet feeding belt 84 is detected (YES in S1 in FIG. 15). However, the pull-out motor 113 is OFF (NO in S2 in FIG. 15), and the rotation of the pull-out roller pair 86 is stopped. Therefore, at this time, it is determined that the document is stopped by skew correction.

Thereafter, the pull-out motor 113 is turned on, and the conveyance of the document MS is resumed by the pull-out roller pair 86. At this time, the paper feed motor 102 is OFF, and as shown in FIG. 13, the upstream portion of the document MS in the transport direction is in the separation nip Ab, so that the paper feed belt 84 is transported by the pull-out roller pair 86. The manuscript MS is rotated along with the original MS. When the trailing edge of the document MS passes through the separation nip Ab, the rotation of the paper feed belt 84 is stopped again, and the stop of the paper feed belt 84 is detected by the photo sensor 142 or the image sensor 146 (S1 in FIG. 15). YES) At this time, the pull-out motor 113 is ON (YES in S2 of FIG. 15), and the paper feed belt 84 is stopped although the document MS is being conveyed by the pull-out roller pair 86. Therefore, it is determined that the trailing edge of the document MS has passed through the separation nip Ab (S3 in FIG. 15).
Then, the controller 100 controls the timing of driving ON of the paper feed motor 102 using the detection of the trailing edge of the document MS as a trigger.

  In this manner, in addition to the presence or absence of the rotation of the paper feed belt 84, the presence or absence of the rotation of the pull-out roller 86 downstream thereof is checked to distinguish whether the document MS has stopped or the document trailing edge has passed through the separation nip Ab. It is possible to accurately determine that the trailing edge of the document has passed through the separation nip Ab.

  The ON / OFF determination of the pull-out motor 113 can be detected by the controller 100 receiving a control signal for the pull-out motor 113. Examples of the control signal for the pull-out motor 113 include an enable signal for the stepping motor driver and a mode signal for determining the excitation method. By using the motor control signal to detect the rotation of the pull-out roller pair 86, there is an advantage that it is not necessary to add a new sensor or encoder.

  In the above description, whether or not the document MS is being conveyed or stopped is detected based on whether or not the pull-out roller pair 86 is rotated. However, based on whether or not the intermediate roller 66 and the reading entrance roller 90 are rotated, the document MS is being conveyed or stopped. This may be detected to determine whether the stop of the paper feed belt 84 is due to the stop of the conveyance of the document or whether the trailing edge of the document has passed through the separation nip Ab. However, in this case, it is necessary to rotate the intermediate roller 66 and the reading entrance roller 90 at the same time as the pull-out roller pair 86 is driven to rotate. This is because when the intermediate roller 66 and the reading entrance roller 90 are driven to rotate after a predetermined time has elapsed since the pull-out roller pair 86 is driven to rotate, the original MS is already present when the intermediate roller 66 and the reading entrance roller 90 are driven to rotate. This is because the rear end may be missing. The roller that stops the original MS by abutting the leading end thereof is preferably a pull-out roller pair 86 disposed at a position closest to the separation nip Ab. This is because, when skew correction is performed by abutting the leading edge of the document MS with the intermediate roller pair 66 or the reading entrance roller pair 90 downstream of the pull-out roller pair 86, the length of the document MS in the transport direction is short. The trailing edge of the document MS may pass through the separation nip Ab before the leading edge of the document hits the intermediate roller pair 66 or the reading entrance roller pair 90. As a result, even if the conveyance of the next original is started with the feeding belt 84 being stopped and the roller downstream in the conveyance direction from the separation nip Ab being driven as a trigger, Since the sheet has already passed through the separation nip, the sheet gap cannot be sufficiently packed. As shown in FIG. 13, since a document shorter than the transport path length t from the separation nip Ab to the nip Ac of the pull-out roller pair 86 cannot be transported, the leading edge of the document MS is abutted against the pull-out roller pair 86. In the case of the configuration in which the document MS is stopped, in all the documents that can be transported by the ADF 51, when the transport of the document is stopped, the trailing edge of the document can be positioned upstream of the separation nip Ab in the transport direction. As a result, when the pull-out roller pair 86 is driven to rotate and the conveyance of the original is resumed, the paper feed belt 84 is stopped along with the original, so that it is detected that the trailing edge of the original has passed through the separation nip Ab. be able to.

  In the above description, the controller 100 controls the timing of turning on the paper feed motor 102 by using the trailing edge of the document passing through the separation nip Ab as a trigger to control the timing of feeding the next document. For example, the timing of lowering the pickup roller 80 may be controlled by controlling the timing at which the pickup lifting / lowering motor 101 is turned ON, triggered by the trailing edge of the document passing through the separation nip. In this case, when the lowering of the pickup roller 80 is completed and the pickup roller 80 comes into contact with the document MS on the document table 53, the paper feed motor 102 is turned on to start feeding the next document. Further, the present invention is not limited to this, and a drive source that rotationally drives the pickup roller 80 and a drive source that rotationally drives the paper feed belt 84 may be separated, and the pickup roller 80 may be lowered while rotating. In the present embodiment, the pickup roller 80 is configured to retract the pickup roller 80 from the document on the document table 53 when the abutment sensor 72 detects the leading edge of the document MS. Such a configuration that the retraction operation of the pickup roller 80 is not taken may be adopted. In this case, the timing at which the paper feed motor 102 is turned on is controlled by using the trailing edge of the document passing through the separation nip Ab as a trigger. In the present embodiment, the pickup roller 80 is provided. However, the paper feed belt 84 is extended to a position facing the document placement table 53, and the document feed belt 84 is used to place the paper feed belt 84 on the document placement table 53. It may be configured to pick up the document, and the pickup roller 80 may be omitted. In the present embodiment, a belt member (paper feed belt) is used as a feeding member that imparts a conveyance force to a document in the separation nip Ab. However, a roller member may be used.

  In the above description, the present invention is applied to the ADF 51, but the present invention can be used for the transfer paper supply device 40. By applying the present invention to the transfer paper supply device 40, the gap between the papers can be shortened, and the productivity of the image forming apparatus can be increased.

As described above, the ADF 51 that is the sheet material conveying apparatus according to the present embodiment is based on the document input table 53 serving as a sheet material stacking unit that stacks and stacks a plurality of document materials serving as a sheet material, and a drive input from a paper feed motor 102 serving as a drive source. The paper is driven to rotate, and a paper feed belt 84 as a feeding member for carrying the topmost original among the originals conveyed from the document placement table 53, and a separation nip Ab is formed in contact with the paper feed belt 84. And a reverse roller 85 as a separating member for separating the original conveyed from the mounting table 53 into a single sheet. Further, the paper feed belt 84 is configured to rotate with the original when the drive from the paper feed motor 102 is cut off, and a feed member rotation detection for detecting whether or not the paper feed belt 84 is rotating. A belt rotation detection mechanism 140 serving as means and a controller 100 serving as a rear end detection means for detecting that the rear end of the document has passed through the separation nip Ab based on the detection result of the belt rotation detection mechanism 140 are provided.
Then, after the document is transported by the pull-out roller pair 86 as a downstream transport member disposed downstream of the separation nip Ab in the document transport direction, the paper feed belt is passed from the time when the rear end of the document passes through the separation nip. The paper feed motor 102 with respect to 84 is turned off. As a result, the paper feed belt 84 is rotated along with the original conveyed by the pull-out roller pair 86, and when the rear end of the original passes through the separation nip Ab, the rotation of the paper supply belt 84 is stopped. Accordingly, when the belt rotation detection mechanism 140 detects that the rotation of the paper feed belt 84 has stopped, the controller 100 can detect that the trailing edge of the document has passed through the separation nip Ab.
As a result, it is possible to detect that the trailing edge of the document has passed through the separation nip, and the conveyance control of the next document can be performed immediately after the trailing edge of the document has passed through the separation nip Ab. It is possible to increase productivity during continuous conveyance.

  Further, the reverse roller 85 is input with a drive for moving the surface of the separation nip Ab in the direction opposite to the surface movement direction of the sheet feeding belt 84, and the surface thereof is directly applied to the sheet feeding belt 84 or a single sheet material. In the state of contacting through the sheet, the surface of the sheet feeding belt 84 is moved. Thereby, the original can be separated into one sheet by the separation nip Ab.

  The controller 100 also starts transport control of the next document based on the result of detecting that the trailing edge of the document has passed through the separation nip. Thereby, the space between sheets can be narrowed, and the productivity at the time of continuous conveyance can be increased.

  Further, according to the ADF 51 of the present embodiment, the document stack placed on the document placement table 53 is opposed to the document stack, and at least the uppermost document of the document bundle loaded on the document placement table 53 is called and directed to the separation nip Ab. And a pickup roller 80 as a calling member to be conveyed, and contact / separation means (consisting of a contact / separation cam and a pickup lifting / lowering motor 101) for bringing the pickup roller 80 into and out of contact with a bundle of documents stacked on the document table 53. ing. When the pickup roller 80 transports at least the uppermost document of the document bundle loaded on the document placement table 53 to the separation nip Ab, the pickup roller 80 is moved from the document bundle loaded on the document placement table 53 by the contact / separation means. It is controlled to be separated. When the controller 100 detects that the trailing edge of the document has passed through the separation nip Ab, the controller 100 brings the pickup roller 80 into contact with the document bundle loaded on the document placing table 53 by the contacting / separating means. As a result, it is possible to control the pickup roller to come into contact with the bundle of documents immediately after the trailing edge of the document passes through the separation nip, so that the gap between the sheets can be narrowed and the productivity during continuous conveyance can be increased. it can.

  In addition, an encoder wheel, an encoding sticker, or the like is used as a means for detecting the rotation of the paper feed belt 84 by detecting the presence or absence of the rotation of the paper feed belt 84 using an image sensor, as compared with the case where a rotary encoder is used. The number of parts can be reduced.

  Further, a rotary encoder may be used as means for detecting the presence or absence of rotation of the paper feed belt 84.

  Further, the controller 100 as the downstream conveying means rotation detecting means for detecting whether or not the pull-out roller pair 86 as the sheet material conveying means disposed downstream of the separation nip Ab in the document conveying direction is rotating. When the belt rotation detection mechanism 140 detects the rotation stop of the sheet feeding belt in the state where the rotation is detected by the 86, it is determined that the trailing edge of the sheet material has been detected. As a result, even when the document is temporarily stopped by registration or skew correction, it can be detected that the trailing edge of the document has passed through the separation nip Ab.

  Further, the controller 100 detects the presence or absence of rotation of the pull-out roller pair 86 based on a drive signal input to the pull-out motor 113 that is a drive source for driving the pull-out roller pair 86. Thereby, the presence or absence of rotation of the pull-out roller pair 86 can be detected without providing an image sensor or a rotary encoder.

  In addition, the controller 100 detects whether the rotation is present or not by using a pair of pull-out rollers 86 arranged in the uppermost stream among the conveying means arranged downstream of the separation nip, thereby reducing the length of the original in the conveying direction. Even so, when the rotation of the pull-out roller pair 86 is started, the trailing edge of the document can be positioned upstream of the separation nip. As a result, even if the document has a short length in the conveying direction, it can be detected that the trailing edge of the document has passed through the separation nip when the rotation of the paper feeding belt is stopped and the pull-out roller is rotating. .

  An image including a document conveying unit that conveys a document MS as a sheet material, and a first fixed reading unit 151 and a second fixed reading unit 95 that are reading units that read a document image of the document MS conveyed by the document conveying unit. In the image reading unit 50 which is a reading apparatus, the ADF 51 of the present embodiment is used as the document conveying means, so that the space between the conveyed documents MS can be reduced, so that productivity when reading documents continuously is achieved. Can be improved.

  In the copier 500, which is an image forming apparatus that includes an image reading unit and an image forming unit 1 that forms an image based on a document image read by the image reading unit, the present embodiment is used as an image reading unit. By providing the image reading unit 50, it is possible to improve productivity when continuously reading a document, and therefore it is possible to improve productivity when continuously copying.

1: Image forming unit 50: Image reading unit 53: Document placement table 66: Intermediate roller 80: Pickup roller 82: Drive roller 83: Driven roller 84: Paper feed belt 85: Reverse roller 86: Pull-out roller pair 100: Controller 101: Pickup lift motor 102: paper feed motor 113: pull-out motor 140: belt rotation detection mechanism 141: encoder wheel 142: photo sensor 146: image sensor

Patent 3618898 Japanese Patent No. 3397606

Claims (12)

A sheet material stacking unit that stacks and stacks a plurality of sheet materials;
A feeding member that is rotationally driven by a driving input from a driving source and feeds the uppermost sheet material among the sheet materials conveyed from the sheet material stacking unit;
In a sheet material conveying apparatus comprising: a separation member that contacts the feeding member to form a separation nip, and separates the sheet material conveyed from the sheet material stacking unit into one sheet,
The feeding member is configured to rotate with the sheet material when driving from the driving source is cut off,
A feeding member rotation detecting means for detecting whether or not the feeding member is rotating;
A sheet material conveying apparatus comprising: a rear end detecting unit configured to detect a rear end of the sheet material based on a detection result of the feeding member rotation detecting unit. In the sheet | seat material conveying apparatus of Claim 1,
The drive source is turned off after the sheet material is conveyed by the downstream conveyance member disposed downstream of the separation nip in the sheet material conveyance direction until the trailing edge of the sheet material passes through the separation nip. Controlled to be
The trailing edge detecting means detects that the trailing edge of the sheet material has passed through the separation nip when the feeding member rotation detecting means detects that the rotation of the feeding member has stopped. Conveying device. In the sheet material conveying apparatus according to claim 1 or 2,
The separation member is input with a drive for moving the surface in a direction opposite to the surface movement direction of the feeding member at the separation nip, and the surface contacts the feeding member directly or via a single sheet material. A sheet material conveying apparatus, wherein the sheet material conveying device is a double-feed prevention roller that rotates with the movement of the surface of the feeding member. In the sheet material conveying apparatus according to any one of claims 1 to 3,
A sheet material conveying apparatus which starts conveying the next sheet material based on the detection result of the trailing edge detecting means. In the sheet material conveying apparatus according to claim 4,
A calling member disposed opposite to the sheet bundle stacked on the sheet material stacking unit, for calling at least the uppermost sheet material of the sheet bundle stacked on the sheet material stacking unit and transporting the sheet material toward the separation nip;
Contact and separation means for bringing the calling member into and out of contact with the sheet bundle loaded on the sheet material stacking unit;
When the calling member conveys at least the uppermost sheet material of the sheet bundle stacked on the sheet material stacking unit to the separation nip, the sheet bundle stacked on the sheet material stacking unit by the contacting / separating means. Control to be separated from
The sheet material conveying apparatus according to claim 1, wherein the calling member is brought into contact with the sheet bundle stacked on the sheet material stacking unit by the contact / separation unit based on a detection result of the rear end detection unit. In the sheet material conveying apparatus according to any one of claims 1 to 5,
An image sensor is used as a feeding member rotation detection unit. In the sheet material conveying apparatus according to any one of claims 1 to 5,
A sheet material conveying apparatus using a rotary encoder as a feeding member rotation detecting means. In the sheet material conveying apparatus according to any one of claims 1 to 7,
A downstream conveyance member rotation detection unit that is disposed downstream of the separation nip in the sheet material conveyance direction and detects whether or not a downstream conveyance member that conveys the sheet material is rotating;
The trailing edge detecting means is a sheet material when the downstream conveying member rotation detecting means detects the rotation of the downstream conveying member when the feeding member rotation detecting means stops the rotation of the feeding member. It determines with having detected the rear end of the sheet material conveying apparatus characterized by the above-mentioned. In the sheet material conveying apparatus according to claim 8,
The downstream conveying member rotation detecting means detects the presence or absence of rotation of the downstream conveying member based on a drive signal input to a driving source that drives the downstream conveying member. apparatus. In the sheet material conveyance device according to claim 8 or 9,
The downstream conveying member rotation detecting means detects whether or not the downstream conveying member arranged upstream in the sheet material conveying direction among the plurality of downstream conveying members arranged downstream from the separation nip is rotated. The sheet | seat material conveying apparatus characterized by the above-mentioned. An original conveying means for conveying original paper as a sheet material;
In an image reading apparatus provided with reading means for reading a document image of a document sheet conveyed by the document conveying means,
An image reading apparatus using the sheet material conveying device according to claim 1 as the document conveying means. Image reading means;
An image forming apparatus comprising: an image forming unit that forms an image based on a document image read by the image reading unit;
An image forming apparatus comprising the image reading apparatus according to claim 11 as the image reading means.

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