JP2011051746A - Medium carrying device, image reader and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a document carrying device capable of specifying a dimension of a carrying object medium before separating a document of the uppermost position from the other document without detecting a co-rotation quantity of a member of co-rotating accompanied by the movement of the document of the uppermost position when carrying the document placed in a document tray in order from the uppermost position. <P>SOLUTION: As a constitution of the document carrying device, a device is adopted for delivering the document placed in the document tray by a delivery roll 13 and detecting a positional change in a rotary shaft 13A caused in the vertical direction by a displacement sensor 5 when the rear end of the document 1 sent out by send-out roll pairs 14 and 15 passes through a contact position with the delivery roll 13 when separating and sending out the delivered document one by one by the send-out roll pairs 14 and 15, and specifies the size of the document by using a detection result of at least the displacement sensor 5. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a medium conveying apparatus, an image reading apparatus, and an image forming apparatus.

  Japanese Patent Application Laid-Open No. 2001-177699 discloses a document that detects at least one end of a document in the main scanning direction after the leading edge of the document sent from the automatic document feeder is conveyed to the main scanning size detection position of the document. A reference length in the sub-scanning direction of the document from the main scanning size detection position is located in the middle of the document scanning path between the main scanning size sensor comprising a reading element and the main scanning size detection position and the document placement position of the automatic document feeder. A sub-scanning size sensor provided at a sub-scanning size detection position that is separated by a certain amount to detect whether the length of the document in the sub-scanning direction is greater than or less than the reference length, and from the main scanning size sensor and the sub-scanning size sensor A document reading apparatus is disclosed that includes a size determination unit that determines the size of a document based on detection information.

  Japanese Patent Laid-Open No. 2004-48282 discloses a document tray on which documents of different sizes supplied to a document reading apparatus can be placed at the same time, and a size of a document placed on the document tray. A back guide which is displaced and positioned in accordance with one original side of the maximum main scanning direction size from among different documents, and is displaced by a displacement amount substantially the same as the back side guide, and has a maximum main scanning direction size. Document detection for detecting a document having a main scanning direction size other than the maximum main scanning direction size, which is simultaneously placed on the basis of the position of the front guide positioned to the other document side and the position of the positioned back guide. A document feeder having a sensor is disclosed.

  Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-107018) includes a document placement unit on which a document is placed, and a transport unit that transports the document from the document placement unit to a document reading unit along a predetermined transport path. A document reading unit that reads the document conveyed to the document reading unit by the conveying unit, a sensor that detects the width of the document before the document reading unit starts reading the document, and the size of the document only by the width information of the document by the sensor. An original reading apparatus including a size specifying unit for specifying is disclosed.

  Japanese Patent Laid-Open No. 6-130762 discloses an automatic document feeder that can load a plurality of documents on a document tray without restriction of the set order for each size. A rotating member that contacts the uppermost paper and rotates with the movement of the uppermost paper is provided, and means for detecting the amount of rotation of the rotating member and a document size corresponding to the amount of rotation are specified. An automatic document feeder including document size specifying means is disclosed.

  Patent Document 5 (Japanese Patent Application Laid-Open No. 6-11922) discloses a document setting unit for placing and setting a document, and a conveyance unit that conveys a document fed from a paper feeding unit to an image reading unit to read an image. A first detection means for detecting movement in the feeding direction of the fed document, and a document feeding device having a carry-out unit that transports the read document and restacks it at a predetermined location; The size of the original conveyed from the original setting unit is specified by combining the second detection means for detecting the length in the direction orthogonal to the feeding direction of the paper and the detection signals from the first and second detection means. There is disclosed a document feeding apparatus comprising a size determination unit that performs the determination and a size signal output unit that outputs a determination signal from the size determination unit.

  Japanese Patent Laid-Open No. 6-75448 discloses a document setting unit for placing and setting a document, and a transport unit for transporting a document fed from a paper feeding unit to an image reading unit to read an image. A first detection means for detecting movement in the feeding direction of the fed document, and a document feeding device having a carry-out unit that transports the read document and restacks it at a predetermined location; The size of the original conveyed from the original setting unit is specified by combining the second detection means for detecting the length in the direction orthogonal to the feeding direction of the paper and the detection signals from the first and second detection means. And a size display means for displaying a determination signal from the size determination means, and one of the second detection means is used as a means for detecting the placement state of the document, Manuscript When the state is detected where abnormalities, original feeding apparatus is disclosed and outputs a signal to alert the state.

JP 2001-177699 A JP 2004-48282 A JP 2004-107018 A JP-A-6-130762 JP-A-6-11922 JP-A-6-75448

  An object of the present invention is to detect the amount of rotation of a member that rotates along with the movement of the uppermost transported medium when transporting the transported medium placed in the medium placing section in order from the uppermost position. Another object of the present invention is to provide a mechanism capable of specifying the dimension of the transported medium before separating the uppermost transported medium from the other transported medium.

The invention described in claim 1
A medium placement unit on which a medium to be transported is placed;
A contact member arranged in contact with the uppermost surface of the medium to be transported placed in the medium placing portion;
Transport means for transporting the transported medium placed in the medium placing section in order from the highest transported medium;
Detecting means for detecting a change in a physical state of the contact member that occurs in a vertical direction when a rear end of the uppermost transported medium transported by the transport means passes through a contact position with the contact member; ,
And a specifying unit that specifies at least a dimension of the uppermost transported medium transported by the transport unit using a detection result of the detection unit.

The invention described in claim 2
The medium conveying apparatus according to claim 1, wherein the detection unit detects a change in the position of the contact member as a change in a physical state of the contact member.

The invention according to claim 3
The medium conveying device according to claim 1, wherein the contact member includes a rotating body that rotates in contact with an uppermost surface of a medium to be conveyed placed on the medium placing portion.

The invention according to claim 4
The conveying means is
A feeding member that sequentially feeds the transported medium placed in the medium placing unit from the highest transported medium;
The medium feeding device according to claim 1, wherein the feeding member also serves as the contact member.

The invention described in claim 5
The feeding member is a rotating member that rotates while being in contact with the uppermost surface of the medium to be transported placed in the medium placing portion,
The detecting means detects a change in a physical state of a rotating shaft that rotates integrally with the rotating member or a bearing member that supports the rotating shaft as a change in a physical state of the feeding member that also serves as the contact member. The present invention relates to the medium conveying device according to claim 4.

The invention described in claim 6
A document transport device for transporting a document;
Reading means for reading an image of a document conveyed by the document conveying device,
The document conveying device includes:
An original placement section where the original is placed;
A contact member disposed in contact with the uppermost surface of the document placed on the document placement unit;
Conveying means for conveying the document placed on the document placing section in order from the topmost document;
Detecting means for detecting a change in a physical state of the contact member that occurs in a vertical direction when a rear end of the uppermost document transported by the transport means passes through a contact position with the contact member;
The image reading apparatus includes: a specifying unit that specifies a dimension of the uppermost document conveyed by the conveying unit using at least a detection result of the detection unit.

The invention described in claim 7
A document transport device for transporting a document;
An image reading device for reading an image of a document conveyed by the document conveying device;
An image recording device for recording an image of a document read by the image reading device on a recording medium,
The document conveying device includes:
An original placement section where the original is placed;
A contact member disposed in contact with the uppermost surface of the document placed on the document placement unit;
Conveying means for conveying the document placed on the document placing section in order from the topmost document;
Detecting means for detecting a change in a physical state of the contact member that occurs in a vertical direction when a rear end of the uppermost document transported by the transport means passes through a contact position with the contact member;
The image forming apparatus includes: a specifying unit that specifies at least a dimension of the uppermost document conveyed by the conveying unit using a detection result of the detection unit.

  According to the first aspect of the present invention, when the medium to be transported placed in the medium holder is transported in order from the top, the amount of the member that rotates along with the movement of the top transport medium is Even if it is not detected, it is possible to realize a medium transport apparatus capable of specifying the dimensions of the transported medium before separating the uppermost transported medium from other transported media.

  According to the second aspect of the present invention, a change in the physical state of the contact member can be detected with a simple configuration as compared with the case where this configuration is not adopted.

  According to the third aspect of the present invention, it is possible to prevent the contact member that contacts the transported medium from being worn.

  According to the invention described in claim 4, the number of parts can be reduced as compared with the case where the present configuration is not adopted.

  According to the fifth aspect of the present invention, it is possible to avoid detection errors caused by dirt or the like adhering to the rotating member due to contact with the transported medium.

  According to the sixth aspect of the present invention, when the document placed on the document placing portion is conveyed in order from the top, the amount of rotation of the member that rotates along with the movement of the topmost document is not detected. However, it is possible to realize an image reading apparatus including a document conveying device capable of specifying the size of a document before separating the top document from other documents.

  According to the seventh aspect of the present invention, when the document placed on the document placing portion is conveyed in order from the top, the amount of rotation of the member that rotates along with the movement of the topmost document is not detected. However, it is possible to realize an image forming apparatus including a document conveying device capable of specifying the size of a document before separating the top document from other documents.

1 is a schematic diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present invention. 1 is a plan view showing a part of the configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a perspective view showing a part of the configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating an overall configuration of an image reading apparatus according to an embodiment of the present invention. 1 is a perspective view illustrating an appearance of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic side view illustrating a configuration of a main part of an image reading apparatus according to an embodiment of the present invention. It is a figure which shows an example of the support mechanism of a rotating shaft. It is a figure which shows the structural example of a displacement sensor. It is a figure explaining the principle of a displacement sensor. It is a figure which shows the change of the output signal level of a displacement sensor. 6 is a flowchart illustrating an example of a processing procedure of the image reading apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating an example of a processing procedure performed to specify the size of a document when a document placed on a document tray is conveyed.

  Hereinafter, a specific embodiment when the medium conveying apparatus according to the present invention is applied to, for example, an original conveying apparatus that conveys an original as an example of a medium to be conveyed will be described in detail with reference to the drawings. The medium conveying device according to the present invention is not limited to the document conveying device, and may be applied to, for example, a paper conveying device including a manual paper feeding mechanism that handles a recording medium such as paper as a medium to be conveyed.

(Definition of terms)
In the embodiment of the present invention, specific terms will be described after defining terms as follows. In addition, the term described in the above-mentioned "Background Art" column is a term described in each patent document, and is not necessarily used in the same meaning as the term defined here.

  “Original size (dimension)” is defined by “original width” and “original length”. “Original width” refers to the original size in the “main scanning direction” when reading and scanning an original image in the main scanning direction and the sub-scanning direction, and “original length” refers to the original size in the “sub-scanning direction”. Say. In terms of the document transport direction, “document width” refers to the document size in the direction orthogonal to the document transport direction, and “document length” refers to the document size in the document transport direction. Therefore, the “document width direction” corresponds to a direction orthogonal to the document conveyance direction, and the “document length direction” corresponds to the document conveyance direction.

  The “main scanning direction” refers to a direction in which the original and the scanning body relatively move when an image of the original is read using an optical system (lamp, mirror, etc.) mounted on the scanning body such as a carriage. The vertical direction. The “sub-scanning direction” refers to a direction in which the document and the scanning body relatively move when an image of the document is read using an optical system mounted on the scanning body. For this reason, the “main scanning direction” is a direction orthogonal to the “sub-scanning direction”. The “main scanning direction” corresponds to a direction (document width direction) orthogonal to the document conveyance direction, and the “sub-scanning direction” corresponds to the document conveyance direction (document length direction).

  “Document leading edge” refers to the edge of the document placed facing the downstream side in the document transport direction, and “Document trailing edge” refers to the document edge positioned facing the upstream side in the document transport direction. Say. The “side edge of the document” refers to the document edge in a direction orthogonal to the document conveyance direction.

(Configuration of Image Forming Apparatus According to Embodiment of Present Invention)
FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 generally includes an image recording device 110 and an image reading device 10.

  The image reading apparatus 10 is disposed on the upper part of the image forming apparatus 100. The image recording apparatus 110 is disposed below the image forming apparatus 100.

  The image reading device 10 optically reads an image of a document and converts the read image into an image signal. The image recording device 110 records an image on a recording medium P such as paper based on the image signal converted by the image reading device 10.

  Here, the configuration of the image recording apparatus 110 according to the present embodiment will be described.

  As shown in FIG. 1, the image recording apparatus 110 according to the present embodiment includes a plurality of recording medium accommodating portions 120 and 121 at the lower portion thereof.

  The recording medium storage units 120 and 121 store recording media P of different sizes. For example, the recording medium accommodating unit 120 accommodates a B5 size recording medium P, and the recording medium accommodating unit 121 accommodates a B4 size recording medium P.

  Immediately above the leading end side (right end side in FIG. 1) of the recording medium accommodating portions 120 and 121, the recording medium P rotates in contact with the leading end side of the upper surface of the recording medium P, and the recording medium P is sent out from the recording medium accommodating portions 120 and 121. A delivery roll 126 is disposed.

  In the image recording apparatus 110, a conveyance path 122 is formed that extends from the leading ends of the recording medium accommodating portions 120 and 121, curves in an S shape, and extends toward the top of the image recording apparatus 110.

  A plurality of (for example, six) pairs of conveyance rolls 164 and registration rolls 168 are arranged along the conveyance path 122 in order from the upstream side in the conveyance direction of the recording medium. Each of the transport roll pairs 164 and the resist roll 168 transports the recording medium P in a sandwiched state.

  An image recording unit 130 that records an image on the recording medium P is disposed above the recording medium accommodating unit 121. The image recording unit 130 is configured to form (print out) an image on the recording medium P based on an electrophotographic method as an example of a recording method.

  The recording medium P accommodated in the recording medium accommodation units 120 and 121 is sent out by the delivery roll 126, transported through the transport path 122 by the transport roller pairs 164 and the resist roll 168, and sent to the image recording unit 130.

  The image recording unit 130 forms a color image on the recording medium P sent from the recording medium storage units 120 and 121 using, for example, cyan, magenta, yellow, and black toners. Incidentally, in addition to forming a color image, the image recording unit 130 may form a black and white image using black toner.

  The image recording unit 130 is provided with four photosensitive drums 112 that can be rotated side by side. Each photoconductive drum 112 is rotated in the direction of arrow K by a driving unit (not shown).

  A charging roll 114 is disposed at a lower left portion of each photosensitive drum 112 so as to contact the photosensitive drum 112. The charging roll 114 charges the surface of the photosensitive drum 112 to a predetermined potential.

  After charging, exposure is performed by light emitted from each exposure head 116 disposed below each photosensitive drum 112, and a latent image corresponding to the image signal converted by the image reading device 10 is formed on the surface of the photosensitive drum 112. Formed.

  The developing roller 119 of each color developing device 118 holds toner of each color charged to a predetermined polarity. The latent image formed on the surface of each photosensitive drum 112 is developed by applying a developing bias to the developing roll 119 and becomes a toner image of each color.

  Each color toner image formed on each of the four photosensitive drums 112 is transferred onto the intermediate transfer belt 113 disposed above each of the photosensitive drums 112 by the first transfer roll 115, and is transferred onto the intermediate transfer belt 113. To be a full-color toner image.

  The recording medium P sent out from the recording medium storage units 120 and 121 and conveyed by the conveyance roll pair 164 is sent between the second transfer roll 132 and the intermediate transfer roll 134 by the registration roll 168 at a predetermined timing, and is full color. The toner image is transferred to the recording medium P. At this time, the toner image is transferred to the surface of the recording medium P on the intermediate transfer roll 134 side.

  The recording medium P on which the full-color toner image is transferred is sent to the fixing device 136. The fixing device 136 fixes the toner image on the recording medium P with heat and pressure. The recording medium P on which the toner image is fixed is discharged to the paper discharge tray 140 by the discharge roll 142.

  Note that the toner image is not completely transferred to the intermediate transfer belt 113 and the recording medium P, and a part of the toner image remains on the photosensitive drum 112 and the intermediate transfer belt 113 as residual toner. Residual toner on the photosensitive drum 112 is removed by a cleaning roll 144, and residual toner on the intermediate transfer belt 113 is removed by a cleaning device 138.

(Configuration of Image Reading Apparatus According to Embodiment of the Present Invention)
Next, the configuration of the image reading apparatus according to the embodiment of the present invention will be described with reference to FIGS.

  The image reading apparatus 10 according to the present embodiment has a function as a document conveying device that conveys a document in addition to a function of reading a document image. An upper part of the image reading apparatus 10 is provided with a document tray 11 as an example of a document placement unit on which a document is placed, and a tray lifter 12 that raises and lowers the document tray 11. The document tray 11 is maintained in a stopped state at the same position (height) during document conveyance (from conveyance start to conveyance completion). Normally, a document bundle in which a plurality of documents are collectively overlapped is placed on the document tray 11, but only one document may be placed. In addition, on the document tray 11, not only documents of the same size but also a plurality of documents (document bundles) having at least one of the document length and document width defining the document size are simultaneously placed (mixed). ) Is possible.

  The image reading apparatus 10 is an example of a transport unit 37 that transports a document placed on the document tray 11 in order from the topmost document, and an example of a reading unit that reads an image of the document transported by the transport unit 37. And a processing device 80 for processing an image signal based on an image of a document read by the reading unit 70.

  The transport unit 37 includes a feed roll 13 and feed roll pairs 14 and 15. Further, the transport unit 37 serves as a transport path for transporting a document, as a first transport path 31, a second transport path 32, a third transport path 33, a fourth transport path 34, a fifth transport path 35, and a sixth transport path. 36.

  The feeding roll 13 is held at a position retracted upward so as to be separated from the original tray 11 during standby when no original is placed on the original tray 11. When document conveyance is started with the document placed on the document tray 11, the document is lowered from the retracted position to contact the uppermost surface of the document, and the document is fed from the document tray 11 by rotating in this state. .

  The feeding roll 13 sequentially feeds the document placed on the document tray 11 raised by the tray lifter 12 from the topmost document. The pair of feed rolls 14 and 15 feeds the originals fed by the feed roll 13 one by one to the downstream side in the transport direction. The feeding roll 13 is provided as an example of a feeding member, and the feeding roll pairs 14 and 15 are provided as examples of a feeding member.

  The first transport path 31 is a transport path through which a document placed on the document tray 11 is sent out first. In the first transport path 31, in addition to the delivery roll pairs 14 and 15 described above, a takeaway roll 16, a pre-registration roll 17, a registration roll 18, a platen roll 19, and an out roll 20 are provided on the downstream side from the upstream side of the transport path. Are arranged in order. The first transport path 31 is provided with a baffle 41 that rotates around a fulcrum according to the loop state of the transported document.

  The takeaway roll 16 conveys the originals separated and sent one by one by the delivery roll pairs 14 and 15 toward the downstream roll. The pre-registration roll 17 conveys the original conveyed by the takeaway roll 16 toward the further downstream roll, and the original by a predetermined conveyance amount with the leading edge of the conveyed original abutting against the registration roll 18. , A so-called loop is formed in which the document is bent in a loop shape before (upstream side) the registration roll 18. When forming the document loop, the baffle 41 is displaced so as to escape outward from the fulcrum as a center, thereby functioning so as not to prevent the document loop formation.

  The registration roll 18 once stops conveyance of the original by abutting against the registration roll 18, and then resumes rotation at the same timing, and supplies the original while performing registration adjustment to the reading unit 70. The platen roll 19 assists the conveyance of the document being read (passing through the second platen glass 72B). The out roll 20 conveys the read original further downstream.

  The second conveyance path 32 and the third conveyance path 33 are branched on the downstream side of the out-roll 20. A switching gate 42 is provided at a branch portion of the second conveyance path 32 and the third conveyance path 33. The switching gate 42 switches the path of the document transported by the out-roll 20 to the second transport path 32 or the third transport path 33.

  A first discharge roll 21 is provided at the end of the second transport path 32. The first discharge roll 21 discharges the document transported to the second transport path 32 onto the discharge tray 40.

  A fourth conveyance path 34 is formed on the downstream side of the third conveyance path 33 for switching back the document that has passed through the third conveyance path 33. The fourth transport path 34 is provided with an inverter roll 22 and an inverter pinch roll 23 for switching back the document.

  The fifth conveyance path 35 includes a fourth conveyance path 34 and a first conveyance path 31 for guiding the document switched back by the inverter roll 22 and the inverter pinch roll 23 in the fourth conveyance path 34 to the first conveyance path 31. Are connected.

  The sixth transport path 36 and the second transport path 32 are used to guide the document switched back by the inverter roll 22 and the inverter pinch roll 23 in the fourth transport path 34 to the second transport path 32. Are connected. A second discharge roll 24 is arranged in the middle of the sixth transport path 36.

  The switching gate 43 switches the path of the document switched back by the inverter roll 22 and the inverter pinch roll 23 in the fourth transport path 34 to the fifth transport path 35 or the sixth transport path 36.

  The reading unit 70 is provided in the lower part of the image reading apparatus 10. The reading unit 70 has a configuration for optically reading an image of a document conveyed by the conveyance unit 37. As an example of a document table, a first platen glass 72A and a second platen glass 72B are provided on the upper part of the apparatus frame 71 forming the casing of the reading unit 70.

  The first platen glass 72A serves as a document table for placing a document (including a book) to be imaged in a stationary state and reading an image of the stationary document. The second platen glass 72B serves as a document table for reading an image of a document being transported (moving) when a document to be read is placed on the document tray 11 and transported by the transport unit 37. .

  A full rate carriage 73 and a half rate carriage 75 are incorporated in the apparatus frame 71 of the reading unit 70. The full rate carriage 73 is equipped with an illumination lamp 74 that irradiates light on the original and a first mirror 76A that receives reflected light obtained from the original. The half-rate carriage 75 is equipped with a second mirror 76B and a third mirror 76C that guide the light obtained from the first mirror 76A to the imaging unit.

  The imaging unit is configured using an imaging lens 77 and a CCD (Charge Coupled Device) image sensor 78. The imaging lens 77 optically reduces the optical image reflected by the third mirror 76C. The CCD image sensor 78 generates an image signal by photoelectrically converting the optical image formed by the imaging lens 77. The CCD image sensor 78 is mounted on the drive substrate 79. The image signal obtained by the CCD image sensor 78 is sent to the processing device 80 via the drive substrate 79. The processing device 80 is adapted to send an image signal to the exposure head 116.

  When reading an image of a document placed on the first platen glass 72A, the full rate carriage 73 and the half rate carriage 75 move in the scanning direction (arrow direction) at a ratio of 2: 1. At this time, the light of the illumination lamp 74 of the full rate carriage 73 is irradiated on the surface to be read of the document, and the reflected light from the document is reflected in the order of the first mirror 76A, the second mirror 76B, and the third mirror 76C. Guided to the imaging lens 77.

  The light guided to the imaging lens 77 forms an image on the light receiving surface of the CCD image sensor 78. The CCD image sensor 78 is a one-dimensional sensor and processes one line at the same time. By repeating the reading in the line direction (main scanning direction) in units of one line while the full rate carriage 73 and the half rate carriage 75 moving in the scanning direction are moved, an image for one page of the document is read.

  On the other hand, the second platen glass 72B is constituted by a transparent glass plate having a long plate-like structure, for example. The document conveyed by the conveyance unit 37 passes over the second platen glass 72B. At this time, the full-rate carriage 73 and the half-rate carriage 75 are stopped at the solid line position (left end) shown in FIG. 1, and the image of the document being conveyed in this state is read as follows.

  First, the light of the illumination lamp 74 of the full-rate carriage 73 is irradiated on the surface to be read of the document pressed against the upper surface of the second platen glass 72B by the platen roll 19 of the transport unit 37, and the reflection from the document is performed. The light is reflected in the order of the first mirror 76A, the second mirror 76B, and the third mirror 76C and guided to the imaging lens 77. Similarly to the above, one line is processed simultaneously by the CCD image sensor 78 which is a one-dimensional sensor. By repeating this reading in units of one line while the document moving on the second platen glass 72B is moving (during conveyance), an image for one page of the document is read.

  The image reading apparatus 10 according to the present embodiment employs center registration that transports a document with reference to the center position in a direction orthogonal to the document transport direction A and reads the image of the document that is being transported. In realizing this center registration, a pair of document guides 61 and 62 are provided on the document tray 11 for positioning the document as a center distribution in the main scanning direction.

  The pair of document guides 61 and 62 is provided as an example of a positioning member that positions the document placed on the document tray 11 in the main scanning direction. Of the pair of document guides 61, 62, one document guide 61 is arranged on the back side as viewed from the standing position of the user who uses (operates) the image forming apparatus 100, and the other document guide 62 is used for the use. It is arranged on the near side when viewed from the standing position of the person. For this reason, in the following description, one document guide 61 is also referred to as a back guide 61 and the other document guide 62 is also referred to as a front guide 62.

  The back guide 61 and the front guide 62 are configured to be movable in a direction (document width direction) perpendicular to the document transport direction A by a slide groove 65 formed in the document tray 11.

  Further, the back side guide 61 and the near side guide 62 are respectively abutted against one side (back side) side edge and the other side (front side) side edge of the document so that both side edge positions of the document are aligned. To position the document.

  Further, the back side guide 61 and the near side guide 62 are respectively connected to a rack 63 provided on the back side of the document tray 11 (inside the document tray). The rack 63 extending from the back guide 61 and the rack 63 extending from the front guide 62 are engaged with a common pinion 64. As the racks 63 and the pinions 64 are engaged, the back side guide 61 and the near side guide 62 are moved in the direction of approaching or separating from each other by the same amount in the document width direction. At this time, if the back side guide 61 and the near side guide 62 are arranged at positions that are equal to the left and right from the center position in the document width direction (if the center is distributed), the back side guide 61 and the near side guide 62 are arranged. The center position between is maintained at the same position even after these guides slide.

  As shown in FIG. 3, the image reading apparatus 10 includes a first document width detection sensor 50 as an example of a first document width detection unit that detects the document width of a document placed on the document tray 11. The first document width detection sensor 50 includes a plurality of optical sensors 54 arranged along a moving body 52 that moves integrally with the back side guide 61 as the back side guide 61 slides.

  The moving body 52 is configured by a plate body bent in an L-shaped cross section, and is configured integrally with the rack 63 of the back side guide 61. A plurality of openings 53 are provided in the moving body 52. Each opening 53 is provided at a position different from each other in the moving direction (original width direction) of the moving body 52. In addition, although the several opening 53 is provided in the mobile body 52 here, it may replace with the said opening 53, and may provide a notch (not shown), for example.

  Each of the plurality of optical sensors 54 constituting the first document width detection sensor 50 includes a light emitting unit 54A and a light receiving unit 54B. The portion of the moving body 52 where the opening 53 is formed moves between the light emitting portion 54A and the light receiving portion 54B of each optical sensor 54. In the state where the opening 53 of the moving body 52 is positioned between the light emitting unit 54A and the light receiving unit 54B of the optical sensor 54, the light sensor 54B receives the light emitted from the light emitting unit 54A. It becomes a state. Further, when the opening 53 of the moving body 52 is not positioned between the light emitting portion 54A and the light receiving portion 54B of the optical sensor 54, the light emitted from the light emitting portion 54A is blocked by the moving body 52 and the light receiving portion 54B does not receive light. Therefore, the optical sensor 54 is turned off.

  When the number of sensors of the plurality of optical sensors 54 constituting the first document width detection sensor 50 is three, the on / off state of the three optical sensors 54 is switched in eight patterns depending on the positions of the document guides 61 and 62. The relative positional relationship between each opening 53 of the moving body 52 and each optical sensor 54 is set.

  More specifically, first, for convenience of explanation, as shown in FIG. 3, the three optical sensors 54 are arranged in order from the side closer to the front guide 62, the optical sensor 54-1, the optical sensor 54-2, and the optical sensor 54-. 3, and the four openings 53 formed in the moving body 52 are distinguished from the opening 53-1, the opening 53-2, the opening 53-3, and the opening 53-4 in order from the side closer to the front guide 62. .

  In such a case, the patterns of the on / off states of the three optical sensors 54-1, 54-2, 54-3 are eight patterns as shown in Table 1 below according to the positions of the document guides 61, 62. It corresponds to any one of.

  In Table 1, pattern 1 is a pattern in which the optical sensor 54-1 is on and the optical sensors 54-2 and 54-3 are off. Pattern 2 is a pattern in which all of the optical sensors 54-1, 54-2, 54-3 are turned off. Pattern 3 is a pattern in which the optical sensors 54-1 and 54-3 are off and the optical sensor 54-2 is on. Pattern 4 is a pattern in which the optical sensors 54-1 and 54-2 are on and the optical sensor 54-3 is off.

  The pattern 5 is a pattern in which the optical sensors 54-1 and 54-3 are turned on and the optical sensor 54-2 is turned off. Pattern 6 is a pattern in which the optical sensors 54-1 and 54-2 are off and the optical sensor 54-3 is on. Pattern 7 is a pattern in which the optical sensor 54-1 is off and the optical sensors 54-2 and 54-3 are on. The pattern 8 is a pattern in which the optical sensors 54-1, 54-2, and 54-3 are all turned on.

  In this way, by utilizing the difference in the on / off state patterns of the optical sensors 54-1, 54-2, 54-3, the positions of the document guides 61 and 62 are identified by the difference in the on / off pattern. It becomes possible to grasp in which position it exists. The document guides 61 and 62 are simultaneously abutted against both side edges of the document when positioning the document placed on the document tray 11. Therefore, the positions of the document guides 61 and 62 in a state where the document is positioned are positions corresponding to the document width of the document placed on the document tray 11.

  Therefore, it is possible to detect the document width of the document placed on the document tray 11 depending on which of the above eight patterns the on / off state of the three optical sensors 54-1, 54-2, 54-3 described above corresponds to. Become. However, when documents of different sizes are placed on the document tray 11, the document guides 61 and 62 are abutted against both side edges of the document with the maximum width to position the document. For this reason, the document width of the document detected using the first document width detection sensor 50 (the optical sensors 54-1, 54-2, 54-3) is the document width of the documents placed on the document tray 11. Corresponds to the document width of the document with the maximum (hereinafter referred to as “maximum document width”).

  The configuration of the first document width detecting unit that detects the document width of the document placed on the document tray 11 is not limited to the above configuration, and for example, based on the rotation amount and rotation direction of the pinion 64 The document width of the document positioned by the back side guide 61 and the near side guide 62 may be detected by recognizing the positions of the guide 61 and the near side guide 62.

  In the present embodiment, as shown in FIG. 2, the document width of the document transported separated from the document tray 11 by the transport unit 37 in the vicinity of the downstream side of the feed roll 14 in the first transport path 31. A second document width detection sensor 66 is provided as an example of a second document width detection means for detecting the above.

  The second document width detection sensor 66 is configured by using, for example, a plurality of (four in the illustrated example) reflective optical sensors. The second document width detection sensor 66 determines the arrangement interval of each sensor in consideration of the detection of the document width of the document expected to be placed on the document tray 11.

  For example, it is distinguished from the first, second, third, fourth from the detection sensor 66 on the side (inner side) close to the center position that is the reference for center distribution in the document width direction (main scanning direction). Then, when a document having a document width corresponding to a short size (182 mm) of A5 size is conveyed, only the first detection sensor 66 is turned on, and a document corresponding to a short size (210 mm) of A4 size is turned on. When a document with a width is transported, the second detection sensor 66 is turned on, and when a document with a document width corresponding to a short size of B4 size (257 mm) is transported, the detection with the third sensor is performed. When the sensor 66 is turned on and a document having a document width corresponding to a short size of A3 size (297 mm) is conveyed, each of the four detection sensors 66 is in a positional relationship that satisfies the condition for turning on. Sen 66 are arranged by shifting the position in the document width direction.

  In the configuration example shown in FIG. 2, when the originals G1 and G2 of different sizes are mixedly loaded on the original tray 11, the inner side edge of each of the originals G1 and G2 is brought into contact with the inner side guide 61 and the original G1. The second document width detection sensor 66 is disposed closer to the front guide 62 on the assumption that the side end positions on the back side of G2 are aligned, but the present invention is not limited to this. For example, although not shown, the second document width detection sensor 66 is moved to the back side on the premise that the side edge on the near side of each document is brought into contact with the near side guide 62 to align the position of the side edge on the near side of the document. You may arrange | position near the side guide 61. FIG.

  In the present embodiment, as shown in FIG. 4, a document length detection sensor 56 is provided as an example of a document length detection unit that detects the document length of a document placed on the document tray 11. The document length detection sensor 56 detects the document length of the document placed on the document tray 11 on the document tray 11. Regardless of the size of the document, all the documents are placed on the document tray 11 with the leading end positions of the documents aligned. Therefore, the trailing edge position of the document depends on the document length of the document placed on the document tray 11. That is, when comparing a document with a long document length and a document with a short document length, the trailing edge position of the document with a long document length is located farther from the feeding roll 13 than the trailing edge position of the document with a short document length. It will be a thing.

  The document length detection sensor 56 is configured using, for example, a plurality (four in the illustrated example) of reflection type optical sensors. The document length detection sensor 56 determines the arrangement interval of each sensor in consideration of the detection of the document length of the document expected to be placed on the document tray 11.

  For example, counting from the detection sensor 56 on the side close to the feeding roll 13 in the document length direction, when distinguished from the first, second, third, and fourth, it corresponds to the short dimension (182 mm) of A5 size. When a document having a document length to be placed is placed on the document tray 11, only the first detection sensor 56 is turned on, and a document having a document length corresponding to the A4 size short dimension (210 mm) is placed on the document tray 11. In this case, up to the second detection sensor 56 is turned on, and when a document having a document length corresponding to the short dimension (257 mm) of B4 size is placed on the document tray 11, up to the third detection sensor. 56 is turned on, and when a document having a document length corresponding to a short size of A3 size (297 mm) is placed on the document tray 11, the positional relationship that satisfies the condition that all four detection sensors 56 are turned on. Each sensor 56 is arranged by shifting the position in the document length direction.

  When documents of different sizes are placed on the document tray 11, the number of optical sensors that are turned on among the plurality of optical sensors constituting the document length detection sensor 56 is determined by the size of the document having the maximum document length. Therefore, the document length of the document detected on the document tray 11 using the document length detection sensor 56 is the document length of the document having the maximum document length among the documents placed on the document tray 11 (hereinafter, “ Maximum document length ").

  The document detection sensors 68 and 69 are provided in the middle of the first transport path 31. The document detection sensor 68 is disposed downstream of the feed roll pairs 14 and 15 and upstream of the takeaway roll 16 in the document transport direction. The document detection sensor 69 is disposed downstream of the pre-registration roll 17 and upstream of the registration roll 18 in the document transport direction. Document detection sensors 68 and 69 detect the passage of the leading edge and the trailing edge of the document that is transported separately from the document tray 11 by the transport unit 37 at each sensor position. The document detection sensors 68 and 69 are configured using, for example, reflection type optical sensors.

  The first document width detection sensor 50, the second document width detection sensor 66, the document length detection sensor 56, and the document detection sensors 68 and 69 are electrically connected to the control unit 90, respectively. The detection signals of the first document width detection sensor 50, the second document width detection sensor 66, the document length detection sensor 56, and the document detection sensors 68 and 69 are taken into the control unit 90.

The control unit 90 controls the overall operation of the image forming apparatus 100 including the image reading apparatus 10.
For this reason, the operation of various rolls in the transport unit 37, the gate switching operation, and the like are controlled by the control unit 90.

  As shown in FIG. 5, an operation panel 58 as an example of an operation unit that can be operated by a user who uses (operates) the image forming apparatus 100 is provided on the surface of the casing of the image reading apparatus 10. . The operation panel 58 includes a display panel 59 as an example of display means.

  Here, the image reading apparatus 10 according to the present embodiment does not allow conveyance of a document of a different size and a conveyance mode that permits conveyance of a document of a different size (hereinafter, “mixed mode”) (in other words, the same size). A conveyance mode (hereinafter, referred to as “normal mode”) that allows conveyance of only a document of a size is provided.

  In the present embodiment, in the mixed loading mode, originals of different sizes are simultaneously stacked and placed on the original tray 11, the originals are conveyed one by one from the original bundle, and the image of the original is read.

  The mixed loading mode is set by the user selecting through the operation panel 58. When the mixed loading mode is selected, the control unit 90 performs processing based on the mixed loading mode.

  In the normal mode, if the document is correctly placed on the document tray 11 and the positions of the document guides 61 and 62 are adjusted accordingly, the detection result of the document width by the first document width detection sensor 50 and the document length There is no particular problem even if the document size is specified based on the detection result of the document length by the detection sensor 56. However, in the mixed loading mode, since different size documents are placed on the document tray 11, the size of the document specified from the detection result of the first document width detection sensor 50 and the detection result of the document length detection sensor 56, and the actual document. In some cases, the sizes of documents conveyed from the tray 11 do not match (align).

  Therefore, in the mixed loading mode, in addition to the detection result of the first document width detection sensor 50 and the detection result of the document length detection sensor 56, or separately from the detection result, the detection result of the second document width detection sensor 66. And the size of the document is specified based on a detection result of a displacement sensor described later. These detection results are taken into the control unit 90 as an example of information relating to document size detection. The control unit 90 has a function as a specifying unit that specifies the size of the uppermost document conveyed by the conveying unit 37 using at least the detection result of the displacement sensor.

  The size of the document specified by the control unit 90 is an image forming condition applied to the image forming operation of the image forming apparatus 100, for example, a reading range when an image of the document is read by the image reading apparatus 10, or a copy applied to a copy process. This is used to determine the magnification, the size of the recording medium P used for copy processing, and the like.

  FIG. 6 is a schematic side view showing the configuration of the main part of the image reading apparatus according to the embodiment of the present invention. In FIG. 6, the feeding roll 13 is arranged in contact with the uppermost surface 1A of the plurality of documents (document bundle) 1 placed on the document tray 11 described above. When the document tray 11 is an example of a “medium storage unit” and the document is an example of a “conveyed medium”, the feeding roll 13 is in a “contact state with the uppermost surface of the transported medium placed on the medium storage unit”. It also serves as a “contact member arranged in”. The top surface of the document 1 placed on the document tray 11 refers to the top surface of the topmost (top) document 1 among the documents 1,. As described above, the lower outer peripheral surface of the feeding roll 13 is lowered when the feeding roll 13 is lowered from the retracted position when starting the document conveyance, for example, the mass (self-weight) of the feeding roll 13 itself, or an elasticity (not shown). The pressing force using a body (spring or the like) is held in contact with the uppermost surface 1A of the document 1.

  The feeding roll 13 is provided as an example of a rotating member that rotates while contacting the uppermost surface 1A of the document 1 placed on the document tray 11. The outer peripheral surface of the feeding roll 13 is formed using an elastic material having a high friction coefficient such as rubber, for example. For this reason, when the feeding roll 13 is rotated, the uppermost document 1 in contact with the feeding roll 13 is fed toward the feeding roll pairs 14 and 15.

  At this time, if the adhesion between the originals is strong, together with the uppermost original 1, the lower original (such as the second original or the third original counted from the uppermost original) is together. May be paid out. However, between the pair of delivery rolls 14 and 15, the upper delivery roll 14 rotates to apply a conveyance force in the conveyance direction (arrow direction) to the uppermost document 1, while the lower delivery roll 15 provides the highest position. A return force opposite to the conveying direction is applied to the other documents. That is, the lower delivery roll 15 functions as a separating unit that separates the originals one by one. The function of the separating means is given, for example, by adopting a configuration in which the lower delivery roll 15 is rotatably supported by a one-way clutch (not shown).

  When such a configuration is adopted, in the state where only one document 1 is sandwiched between the delivery roll pairs 14, 15, as shown in FIG. 6, the document 1 is moved along with the rotation of the delivery roll 14. Thus, the delivery roll 15 rotates in the opposite direction to the delivery roll 14. On the other hand, in a state where a plurality of documents 1 are sandwiched between the delivery roll pairs 14 and 15, the delivery roll 15 supported by the one-way clutch rotates in the same direction as the delivery roll 14. Documents other than the upper document are returned to the document tray 11 side by the rotation of the feed roll 15. For this reason, the originals 1 are sent out from the pair of delivery rolls 14 and 15 in a state of being separated one by one.

  The feeding roll 13 is attached to the rotating shaft 13A. The rotating shaft 13A is configured using, for example, a metal shaft having a circular cross section. As shown in FIG. 7, for example, bearing members 2 are attached to both ends of the rotating shaft 13A. The bearing member 2 is a member that supports the rotating shaft 13A in a rotatable state. The bearing member 2 is fitted in, for example, a vertically long slot 3 </ b> A provided in the frame member 3 of the image reading apparatus 10. 3 A of long holes of the frame member 3 are arrange | positioned in the direction in which the long axis becomes parallel to a perpendicular direction (up-down direction). The bearing member 2 is movable in the long axis direction of the long hole 3A. For this reason, the bearing member 2 can be displaced in the vertical direction integrally with the rotating shaft 13 </ b> A and the feeding roll 13. The vertical direction described here refers to a direction (direction perpendicular to the ground plane) parallel to the direction in which gravity acts.

  The feeding roll 13 and the rotating shaft 13A are rotated integrally with each other. As shown in FIG. 8, a gear 4 is attached to one end side of the rotating shaft 13A as an example of a member that transmits the rotational driving force to the rotating shaft 13A. The gear 4 is attached to the outer side or the inner side of the position where the bearing member 2 is attached, for example, in the central axis direction of the rotating shaft 13A. The gear 4 is coaxially attached to the rotating shaft 13A so as to rotate integrally with the feeding roll 13 and the rotating shaft 13A. The gear 4 meshes with a drive gear that rotates using a drive motor (not shown) (for example, a stepping mode) or a driven gear that meshes with the drive gear. Although the gear 4 is attached to the rotating shaft 13A here, a pulley (not shown) may be attached to the rotating shaft 13A instead of the gear 4.

  A displacement sensor 5 is disposed between the feeding roll 13 and the gear 4 in the central axis direction of the rotating shaft 13A. The displacement sensor 5 is a sensor that detects a change (displacement) in the position of the rotation shaft 13 </ b> A of the feeding roll 13. Since the rotation shaft 13A is displaced in the vertical direction as described above, the displacement sensor 5 detects the displacement (change in height) of the rotation shaft 13A in the vertical direction.

  The displacement sensor 5 includes an actuator 6 and a pair of sensor elements 7 and 8. The actuator 6 is provided so as to be movable in the vertical direction by a support mechanism (not shown). The actuator 6 integrally includes a light shielding portion 6A and a contact portion 6B. The light shielding portion 6A is formed in a plate shape having a triangular shape in the side view (isosceles triangle in the illustrated example). The contact portion 6B is formed at the lowermost portion of the actuator 6 in a plate shape wider than the light shielding portion 6A. The actuator 6 is placed on the rotating shaft 13A, and the lower surface (flat surface) of the contact portion 6B is in contact with the top of the outer peripheral surface of the rotating shaft 13A. For this reason, the contact state of the actuator 6 and the rotating shaft 13A is a line contact state along the central axis direction of the rotating shaft 13A.

  Here, when the rotating shaft 13A rotates in accordance with the driving of the drive motor, the position of the actuator 6 is in any direction including the vertical direction unless the position of the rotating shaft 13A is displaced in the vertical direction. The actuator 6 is supported by the support mechanism (not shown) so as not to be displaced.

  The pair of sensor elements 7 and 8 are arranged so as to sandwich the light shielding portion 6A of the actuator 6 from both sides in the central axis direction of the rotating shaft 13A. A gap is interposed between the pair of sensor elements 7 and 8 and the light shielding portion 6 </ b> A of the actuator 6. Further, the pair of sensor elements 7 and 8 are arranged in a state of facing each other through the light shielding portion 6 </ b> A of the actuator 6. The pair of sensor elements 7 and 8 are provided with their positions fixed. For this reason, even if the actuator 6 is displaced in the vertical direction together with the rotating shaft 13A, the positions of the pair of sensor elements 7 and 8 are maintained unchanged.

  Of the pair of sensor elements 7 and 8, for example, one sensor element 7 is a light emitting element and the other sensor element 8 is a light receiving element. One sensor element 7 emits line-shaped light that crosses the light shielding portion 6A of the actuator 6 in the horizontal direction. The other sensor element 8 receives light that has arrived without being shielded by the light shielding portion 6 </ b> A of the actuator 6 out of the line-shaped light emitted from the one sensor element 7.

  The other sensor element 8 outputs an electrical signal of a level (for example, a voltage level, a current level, etc.) corresponding to the amount of received light. Further, when the actuator 6 is displaced in the vertical direction between the pair of sensor elements 7 and 8, the light shielding portion 6 </ b> A of the actuator 6 is formed in a triangular shape in a side view, so that the light emitted from one sensor element 7 Of these, the amount of light received by the other sensor element 8 changes.

  Specifically, when the actuator 6 is displaced upward in the vertical direction, the light emitting / receiving positions by the pair of sensor elements 7 and 8 are relatively displaced downward by the light shielding portion 6 </ b> A of the actuator 6. When the actuator 6 is displaced downward in the vertical direction, the light emitting / receiving positions by the pair of sensor elements 7 and 8 are displaced relatively upward by the light shielding portion 6 </ b> A of the actuator 6.

  Here, for example, as shown in FIG. 9A, when the light emitting / receiving position by the pair of sensor elements 7 and 8 is at the first height position H1 in the height direction of the actuator 6, Is assumed to be at the second lower height position H2.

  When the light emitting / receiving positions by the pair of sensor elements 7 and 8 are at the first height position H1, light is emitted from the sensor element 7 toward the sensor element 8 as shown in FIG. 9B. When the light emitting / receiving position by the pair of sensor elements 7 and 8 is at the second height position H2, light is emitted from the sensor element 7 toward the sensor element 8 as shown in FIG. Is done. In that case, since the length of the actuator 6 (light-shielding portion 6A) that blocks light changes between the pair of sensor elements 7 and 8, the light emitting / receiving positions by the pair of sensor elements 7 and 8 are the second height positions. The amount of light received by the sensor element 8 is greater in the case of being at the first height position H1 than in the case of being in H2.

  That is, when the actuator 6 is displaced upward in the vertical direction, the amount of light shielded by the light shielding portion 6A of the actuator 6 out of the light emitted from the one sensor element 7 increases, so that the other sensor element 8 reduces the amount of light received. Further, when the actuator 6 is displaced downward in the vertical direction, the amount of light shielded by the light shielding portion 6A of the actuator 6 out of the light emitted from the one sensor element 7 is reduced. The amount of light received at 8 increases. Thus, when the amount of light received by the other sensor element 8 increases or decreases, the level of the electrical signal output from the other sensor element 8 changes accordingly.

  Therefore, in the control unit 90 that captures the detection result of the displacement sensor 5, when the level of the electrical signal output from the other sensor element 8 changes (increases or decreases) to a preset threshold value or more, the actuator 6 It is a mechanism to recognize that has been displaced in the vertical direction. Since the actuator 6 is displaced in the vertical direction together with the rotating shaft 13A that supports the feeding roll 13, recognizing the displacement of the actuator 6 using the displacement sensor 5 recognizes the displacement of the feeding roll 13 and the rotating shaft 13A. It will also be.

  Regarding the “threshold value” described above, for example, the control unit 90 of the image forming apparatus 100 uses computer hardware resources such as a CPU (Central Processing Unit), ROM (Read-Only Memory), and RAM (Random Access Memory). In this case, it may be stored in a ROM (for example, EPROM) which is an example of a nonvolatile memory together with a control program.

  Here, when the document placed on the document tray 11 is transported by the transport unit 37, the document fed by the feed roll 13 is separated one by one by the feed roll pairs 14 and 15 and sent to the first transport path 31. become. At that time, when the trailing edge of the document conveyed between the pair of feed rollers 14 and 15 passes through the contact position with the feed roller 13 on the document tray 11, the position of the feed roller 13 is set in the vertical direction (the thickness direction of the document). ). Specifically, the position of the feeding roll 13 corresponds to the thickness dimension of the document in the vertical direction at the moment when the trailing edge of the document separated and fed by the feeding roll pairs 14 and 15 passes through the contact position with the feeding roll 13. Only changes downward. That is, when the trailing edge of the document fed by the feeding roll pairs 14 and 15 passes at the contact position with the feeding roll 13, the height of the uppermost surface of the document on the document tray 11 is lowered accordingly. Due to the change in the height of the uppermost surface of the document, the feeding roll 13 is displaced downward.

  At this time, the rotating shaft 13 </ b> A that supports the feeding roll 13 and the actuator 6 of the displacement sensor 5 that contacts the rotating shaft 13 </ b> A are also displaced downward together with the feeding roll 13. In the present embodiment, before and after the trailing edge of the document that has been separated and sent out as described above passes through the contact position with the feeding roll 13, it is output from the displacement sensor 5 (the other sensor element 8). The level of the electrical signal is changed to be greater than or equal to the threshold value. Therefore, the control unit 90 determines whether the trailing edge of the document that has been separated and sent out as described above has passed through the contact position with the feeding roll 13 at the level of the electric signal output from the displacement sensor 5. Recognizable from changes.

  Specifically, for example, the level of the electric signal output from the displacement sensor 5 is sequentially acquired in time series at a certain time interval (for example, every several msec), and the level of the electric signal acquired last time and the electric current acquired this time are acquired. Find the difference from the signal level. If the level difference of the obtained electrical signal is less than the threshold value, it is recognized that the trailing edge of the document has not passed the contact position with the feeding roll 13. If the level difference of the obtained electrical signal is equal to or greater than the threshold value, it is recognized that the trailing edge of the document has passed the contact position with the feeding roll 13.

  FIG. 10 is a diagram showing a change in the level of the electrical signal output from the displacement sensor 5. In FIG. 10, the vertical axis represents the level of the electrical signal output from the displacement sensor 5, and the horizontal axis represents time. As described above, when the original fed by the feed roll 13 is separated one by one by the feed roll pairs 14 and 15 and sent to the first transport path 31, the rear end of the original passes through the contact position with the feed roll 13. At timing Tc, the output signal level of the displacement sensor 5 changes to the above threshold value or more.

  The timing Tc at which the output signal level of the displacement sensor 5 changes in this way is based on the timing Ts when the document detection sensor 68 detects the passage of the leading edge of the document fed by the feed roll pairs 14 and 15 as a reference. The longer the document length of the document sent out by 14 and 15, the longer the elapsed time from timing Ts to timing Tc. As for the rotation amount of the drive motor for rotating the feed roll pairs 14 and 15, the rotation amount of the drive motor increases from the timing Ts to the timing Tc as the document length of the document becomes longer.

  FIG. 11 is a flowchart showing an example of a processing procedure of the image reading apparatus according to the embodiment of the present invention. Here, a processing procedure for reading an image of a document placed on the document tray 11 will be described.

  First, the control unit 90 determines whether or not a start button provided on the operation panel 58 has been pressed (step S1). If it is determined that the start button has been pressed, the conveying unit 37 is driven to start conveying the document (step S2). As a result, of the documents placed on the document tray 11, the uppermost document is fed by the rotation of the feeding roll 13, and the fed documents are separated one by one by the rotation of the feeding roll pairs 14 and 15. Sent out.

  Next, when the leading edge of the document reaches the second platen glass 72B through the takeaway roll 16, the pre-registration roll 17, and the registration roll 18, the reading unit 70 reads the image of the document based on an instruction from the control unit 90. Read (step S3).

  At that time, the leading edge of the original conveyed by the pre-registration roll 17 is abutted against the registration roll 18 in a rotation stop state, and the pre-registration roll 17 conveys the original by a predetermined amount in this state, whereby the original is upstream of the registration roll 18. Is bent in a loop shape. In this state, the registration roll 18 starts rotating, whereby the original is conveyed toward the original reading position on the second platen glass 72B.

  Next, the control unit 90 confirms whether or not the double-sided reading mode is designated (step S4). The duplex scanning mode is designated by the user operating the operation panel 58 before pressing the start button.

  If it is determined that the duplex reading mode is designated, the document is reversed and conveyed (step S5). The document is reversed and conveyed in the following procedure.

  First, the document that has passed over the second platen glass 72 </ b> B is sent from the first transport path 31 to the third transport path 33 by the switching gate 42, and then sent from the third transport path 33 to the fourth transport path 34. Next, after the original is switched back by the inverter roll 22 and the inverter pinch roll 23 in the fourth conveyance path 34, the original is sent from the fourth conveyance path 34 to the fifth conveyance path 35 by the switching gate 43. The document thus fed into the fifth conveyance path 35 joins the first conveyance path 31 before (on the upstream side) the pre-registration roll 17.

  Next, similarly to the above, when the leading edge of the document reaches the second platen glass 72B through the pre-registration roll 17 and the registration roll 18, the reading unit 70 reads the image of the document based on an instruction from the control unit 90. (Step S6).

  Next, the document is discharged onto the discharge tray 40 with the front and back reversed (step S7). The original is reversed and discharged in the following procedure.

  First, the document that has passed over the second platen glass 72 </ b> B is sent from the first transport path 31 to the third transport path 33 by the switching gate 42, and then sent from the third transport path 33 to the fourth transport path 34. Next, after the document is switched back by the inverter roll 22 and the inverter pinch roll 23 in the fourth transport path 34, the document is sent from the fourth transport path 34 to the sixth transport path 36 by the switching gate 43. Next, the original is transported toward the first discharge roll 21 by the second discharge roll 24 on the sixth transport path 36. Next, the document is discharged to the discharge tray 41 by the first discharge roll 21.

  On the other hand, if it is determined in step S4 that the duplex reading mode is not designated, the document is discharged (step S8). To discharge the original, the original that has passed over the second platen glass 72B is sent from the first transport path 31 to the second transport path 32 by the switching gate 42 and then discharged to the discharge tray 41 by the first discharge roll 21. To do.

  FIG. 12 is a flowchart showing an example of a processing procedure performed to specify the size of the document when the document placed on the document tray is conveyed.

  First, the control unit 90 confirms whether the user operating the operation panel 58 has selected (designated) the mixed loading mode among the normal mode and the mixed loading mode prepared in advance as selection candidates for the document transport mode. (Step S11). If it is determined that the user has not selected the mixed loading mode, processing based on the normal mode is executed (step S12).

  On the other hand, when it is determined that the user has selected the mixed document mode, the first document width detection is performed when the start instruction is received from the user by pressing the start button (when affirmative determination is made in step S13). After the document width (maximum document width) is detected using the sensor 50 (step S14), the document length (maximum document length) is detected using the document length detection sensor 56 (step S15). Note that either the process of step S14 or the process of step S15 may be performed first.

  Next, in step S16, the control unit 90 drives the conveyance unit 37 in the same manner as in step S2 to start conveyance of the document, and then detects the document width using the second document width detection sensor 66 (step S16). S17). The second document width detection sensor 66 is arranged on the downstream side in the transport direction with respect to the delivery roll pairs 14 and 15. For this reason, the document width detected by the second document width detection sensor 66 corresponds to the document width of the document that is separated and sent out one by one by the feed roll pairs 14 and 15.

  Next, the control unit 90 detects the document length using the displacement sensor 5 (step S18). The document length detection process using the displacement sensor 5 is performed at least after the document sent out by the delivery roll pairs 14 and 15. The end is performed before passing between the pair of delivery rolls 14 and 15 (in other words, before the document is completely separated). An example of document length detection processing using the displacement sensor 5 will be described below.

  First, when comparing the case of conveying a document having a document length = 182 mm and the case of conveying a document having a document length = 364 mm, the timing at which the output signal level of the displacement sensor 5 changes to a threshold value or more is determined by, for example, the document detection sensor 68. Considering the timing of detecting the passage of the leading edge of the document as a starting point, the former is faster than the latter due to the difference in document length.

  For this reason, considering only the standard A plate size and B plate size, the document width detected in step S17 is, for example, 257 mm corresponding to the long dimension of the B5 size and the short dimension of the B4 size. In this case, the document length candidate assumed (predicted) from the document width is, for example, 182 mm corresponding to the short dimension of the B5 size by using the document size correspondence table stored in advance in the nonvolatile memory. And 364 mm corresponding to the longitudinal dimension of B4 size.

  In such a case, the control unit 90, for example, the timing at which the output signal level of the displacement sensor 5 is expected to change to a threshold value or more when a document having a shorter document length (182 mm in this example) is conveyed, and the document A reference timing is set between the timing when the output signal level of the displacement sensor 5 is expected to change to a threshold value or more (for example, at an intermediate time) when a document having a longer length (364 mm in this example) is conveyed. To do. If the output signal level of the displacement sensor 5 changes to a threshold value or more before reaching the reference timing, the document length is detected as 182 mm. If the output signal level of the displacement sensor 5 does not change beyond the threshold value even after the reference timing, the document length is detected as 364 mm.

  The reference timing is a timing that does not change on the time axis even if the length of the document to be conveyed changes. For example, as described above, the upstream of the passage of the leading edge of the document fed by the feed roll pairs 14 and 15 on the upstream side. The timing detected by the document detection sensor 68 and the timing detected by the downstream document detection sensor 69 may be set as the starting point. Further, for example, the reference timing is set based on the timing at which a predetermined time elapses from the timing at which the upstream document detection sensor 68 detects the passage of the leading edge of the document fed by the delivery roll pairs 14 and 15. It may be set.

  Here, for convenience of explanation, two candidate document lengths are assumed based on the document width, and the timing at which the output signal level of the displacement sensor 5 changes to a threshold value or more depends on whether it is before or after reaching the reference timing. Although one of the candidates is detected as the document length, the present invention is not limited to this. For example, when there are three document length candidates assumed from the document width, the document length may be detected as follows.

  That is, of the candidates for the document length, when the candidate document with the shortest document length is conveyed, the timing at which the output signal level of the displacement sensor 5 is expected to change to a threshold value or more, and the candidate with the second shortest document length. The first reference timing is set between the timing when the output signal level of the displacement sensor 5 is expected to change to a threshold value or more when the document is conveyed (for example, at an intermediate time). Further, when the candidate document having the second shortest document length is conveyed, the timing at which the output signal level of the displacement sensor 5 is expected to change to the threshold value or more and the displacement sensor when the candidate document having the longest document length is conveyed. The second reference timing is set between the timing at which the output signal level of 5 is expected to change to a threshold value or higher (for example, at an intermediate time).

  If the output signal level of the displacement sensor 5 changes to a threshold value or more before reaching the first reference timing, the document length is detected in accordance with the document having the shortest document length. Further, when the output signal level of the displacement sensor 5 changes to a threshold value or more during the period from the first reference timing to the second reference timing, the document length is adjusted to the document with the second shortest document length. Detect. If the output signal level of the displacement sensor 5 does not change beyond the threshold even after the second reference timing has passed, the document length is detected in accordance with the document having the longest document length.

  There are roughly three document length candidates assumed from the document width detected using the second document width detection sensor 66, even if an inch-series document (letter, half letter, legal, etc.) is included in the detection target. Although narrowed down below, if the number of candidates increases beyond that, the number of reference timings set may be increased in accordance with the length of each candidate document.

  The document length detection method described above is merely an example, and the document length may be detected by other methods.

  For example, a correspondence table or calculation that associates the relationship between the elapsed time from when the document detection sensor 68 detects the passage of the leading edge of the document until the output signal level of the displacement sensor 5 changes to a threshold value or more and the document length of the document. The program is stored in the non-volatile memory, and the document length is read from the correspondence table based on the elapsed time actually measured using a built-in timer or the like, or the document length is calculated by the arithmetic program. The length of the document may be obtained by calculation.

  Further, for example, with respect to the rotation amount of the drive motor for rotating the delivery roll pair 14, 15, until the output signal level of the displacement sensor 5 changes to a threshold value or more after the document detection sensor 68 detects passage of the leading edge of the document. A correspondence table and a calculation program in which the relationship between the rotation amount of the drive motor and the document length of the document are associated with each other are stored in the non-volatile memory, and the encoder or the like built in the apparatus is actually used. Based on the measured rotation amount of the drive motor, the document length may be obtained by reading the document length from the correspondence table or calculating the document length by the calculation program.

  When the document width and document length are detected in this way, the control unit 90 specifies (determines) the document size from the detected information (step S19). For example, if the document width detected in step S17 is 257 mm and the document length detected in step S18 is 182 mm, the document size is specified as the B5 size of “vertically placed”. If the document width detected in step S17 is 257 mm and the document length detected in step S18 is 364 mm, the document size is specified as B4 size of “landscape”. “Vertical placement” described here means a form in which the original is placed on the document tray 11 with the long side of the document facing the transport direction, and “horizontal placement” means the short side of the document in the transport direction. This means a form in which the document is placed on the document tray 11 facing toward. The specification of the document size by the control unit 90 is performed before the reading of the document image is started in step S3, and more specifically, before the conveyance of the document by the registration roll 18 is started.

(Modification)
In the embodiment of the present invention, the displacement of the rotating shaft 13A of the feeding roll 13 is detected using the displacement sensor 5, but the present invention is not limited to this, and the displacement of the bearing member 2 that supports the rotating shaft 13A is detected. Alternatively, the detection may be performed by a displacement sensor (not shown). In addition to this, for example, the displacement of the feeding roll 13 attached to the rotating shaft 13A may be detected by a displacement sensor (not shown).

  In the embodiment of the present invention, the feeding roll 13 also serves as the “contact member”. However, the present invention is not limited to this, and a configuration in which the “contact member” is provided separately from the feeding roll 13 may be adopted. Further, when such a configuration is adopted, a rotating member of a contact member (not shown) is brought into contact with the uppermost surface of the document (conveyed medium) placed on the document tray 11 as an example of the medium placing unit, The rotating member of the contact member may be rotated (rotated) in accordance with the movement of the document under the contact state.

  In the embodiment of the present invention, the change in the physical state of the feeding roll 13 that occurs in the vertical direction when the trailing edge of the uppermost document conveyed by the conveying unit 37 passes through the contact position with the feeding roll 13. However, the present invention is not limited to this, and for example, a change in vibration (amplitude) of the feeding roll 13 that occurs in the vertical direction may be detected. When such a configuration is employed, the vibration (amplitude) of the feeding roll 13 increases momentarily when the trailing edge of the uppermost document passes through the contact position with the feeding roll 13. Therefore, when the vibration (amplitude) of the feeding roll 13 changes to a predetermined threshold value or more, the control unit 90 determines that the rear end of the uppermost document on the document tray 11 has passed the contact position with the feeding roll 13. Should be recognized.

  DESCRIPTION OF SYMBOLS 2 ... Bearing member, 5 ... Displacement sensor, 10 ... Image reading apparatus, 11 ... Document tray, 13 ... Feeding roll, 13A ... Rotating shaft, 37 ... Conveyance part, 90 ... Control part, 100 ... Image forming apparatus

Claims (7)

A medium placement unit on which a medium to be transported is placed;
A contact member arranged in contact with the uppermost surface of the medium to be transported placed in the medium placing portion;
Transport means for transporting the transported medium placed in the medium placing section in order from the highest transported medium;
Detecting means for detecting a change in a physical state of the contact member that occurs in a vertical direction when a rear end of the uppermost transported medium transported by the transport means passes through a contact position with the contact member; ,
A medium transport apparatus comprising: a specifying unit that specifies a dimension of the uppermost transported medium transported by the transport unit using at least a detection result of the detection unit. The medium conveying apparatus according to claim 1, wherein the detection unit detects a change in the position of the contact member as a change in a physical state of the contact member. The medium conveying apparatus according to claim 1, wherein the contact member includes a rotating body that rotates in contact with an uppermost surface of a medium to be conveyed placed on the medium placing portion. The conveying means is
A feeding member that sequentially feeds the transported medium placed in the medium placing unit from the highest transported medium;
The medium conveying apparatus according to claim 1, wherein the feeding member also serves as the contact member. The feeding member is a rotating member that rotates while being in contact with the uppermost surface of the medium to be transported placed in the medium placing portion,
The detecting means detects a change in a physical state of a rotating shaft that rotates integrally with the rotating member or a bearing member that supports the rotating shaft as a change in a physical state of the feeding member that also serves as the contact member. The medium carrying device according to claim 4. A document transport device for transporting a document;
Reading means for reading an image of a document conveyed by the document conveying device,
The document conveying device includes:
An original placement section where the original is placed;
A contact member disposed in contact with the uppermost surface of the document placed on the document placement unit;
Conveying means for conveying the document placed on the document placing section in order from the topmost document;
Detecting means for detecting a change in a physical state of the contact member that occurs in a vertical direction when a rear end of the uppermost document transported by the transport means passes through a contact position with the contact member;
An image reading apparatus comprising: a specifying unit that specifies a dimension of the uppermost document transported by the transport unit using at least a detection result of the detection unit. A document transport device for transporting a document;
An image reading device for reading an image of a document conveyed by the document conveying device;
An image recording device for recording an image of a document read by the image reading device on a recording medium,
The document conveying device includes:
An original placement section where the original is placed;
A contact member disposed in contact with the uppermost surface of the document placed on the document placement unit;
Conveying means for conveying the document placed on the document placing section in order from the topmost document;
Detecting means for detecting a change in a physical state of the contact member that occurs in a vertical direction when a rear end of the uppermost document transported by the transport means passes through a contact position with the contact member;
An image forming apparatus comprising: a specifying unit that specifies a dimension of the uppermost document conveyed by the conveying unit using at least a detection result of the detection unit.

Images