JP4265553B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus that reads an image of a document conveyed from a paper feed tray to a paper discharge tray via a conveyance path at a predetermined reading position.

  2. Description of the Related Art Conventionally, as an image reading apparatus mounted on a copier, a scanner, or a multi-function device having both of these functions, a CCD (Charge Coupled) 2. Description of the Related Art An image reading unit such as a device (Device) or a CIS (Contact Image Sensor) is provided at a predetermined position to read an image of a document being conveyed.

  For example, in a conventional image reading apparatus as shown in FIG. 9, a document is transported onto a platen glass 91 by an automatic document transport mechanism 90 called ADF (Auto Document Feeder), and is disposed below the platen glass 91. The image of the original passing through the platen glass 91 is read by the image scanner 92. A guide member 93 is provided at a position facing the platen glass 91, and the document is guided by the guide member 93 so as to pass a predetermined position on the platen glass 91. Further, the automatic document conveying mechanism 90 is provided with a conveying roller 94 and a pinch roller 95, and the document is nipped by these and conveyed on the conveying path 96.

  The CCD and CIS used as the image sensor 92 emit light from a light source toward the platen glass 91. The light is reflected by the surface of the document passing over the platen glass 91, and the reflected light enters the image sensor 92. The reflected light is converted into an electric signal by the image sensor 92. In such document image reading, it is known that show-through becomes a problem when the thickness of the document is thin (see, for example, Patent Documents 1 and 2).

  Specifically, as shown in the drawing, a guide member 93 and a transport roller 94 are disposed at a position facing the platen glass 91. Since the transport roller 94 is rotationally driven, a gap is appropriately provided between the guide member 93 and the transport roller 94. Therefore, the guide member 93 and the conveying roller 94 are present at a position facing the platen glass 91 with a predetermined gap in the width direction of the document.

  When a thin original passes through the platen glass 91, a part of the light emitted from the image sensor 92 passes through the original and reaches the guide member 93 and the conveying roller 94, and this reflected light is again transmitted to the original. And enters the image sensor 92. On the other hand, the light reaching the gap between the guide member 93 and the conveyance roller 94 enters the automatic document conveyance mechanism 90 and does not return to the image sensor 92 as reflected light. As described above, at the position where the guide member 93 and the conveying roller 94 are present, the reflected light overlaps with the reflected light from the document, while the portion corresponding to the gap is only the reflected light from the document. The reflectivity differs between the guide member 93 and the conveyance roller 94, and further, no reflected light is generated in these gaps. Therefore, the read image of the document includes the guide member 93, the conveyance roller 94, and the reflected light from these gaps. Depending on the presence or absence and the intensity difference, streaky show-through occurs in the transport direction.

JP 2002-84424 A JP 2003-198810 A

  According to the means disclosed in Patent Document 1, a plurality of types of originals having different transmittances are read and show-through data is created in advance. Then, the show-through data is stored and held in the storage medium of the apparatus. When performing image reading, first, the transmittance of each document is measured, and show-through data corresponding to the transmittance is obtained from the show-through data stored and held. Thereafter, the image reading is performed to acquire image data, and the image data is corrected with the show-through data, so that the show-through can be eliminated.

  According to the means disclosed in Patent Document 2, when reading an image, first, the light transmittance of each document is measured. Control variables such as the amount of light emitted from the image sensor to the document are changed according to the obtained light transmittance. As a result, the amount of light transmitted through the document can be reduced to eliminate the show-through.

  However, in these means, it is necessary to measure the transmittance / light transmittance of each document before reading an image, and an arithmetic means for performing the calculation is required. Further, such a calculation is performed when the document passes over the platen glass 91, and there is a problem that the reading speed is slow due to the calculation process. In addition, data measurement work is required to create the show-through data in advance, and storage means for storing and holding the show-through data is also required. Such an increase in calculation means and storage means increases the number of parts of the image reading apparatus, which causes an increase in the size and cost of the apparatus.

  The present invention has been made in view of such a problem, and an object of the present invention is to provide means for easily preventing show-through caused by a conveyance roller or a guide member without increasing the number of parts.

  An image reading apparatus according to the present invention includes a paper feed tray and a paper discharge tray arranged in two upper and lower stages, and a conveyance path formed in a substantially U shape in a lateral direction so as to connect the paper feed tray and the paper discharge tray. And a conveying means for conveying the document from the paper feed tray to the paper discharge tray via the conveying path, and a curved portion of the substantially U-shaped conveying path in the lateral direction, and the document is moved along the curved portion. A conveyance roller that conveys the paper so as to be reversed; an image reading unit that is disposed at a position facing the conveyance roller and reads an image of a document conveyed in the conveyance path in a predetermined direction at a predetermined reading position; A guide member which is provided opposite to the reading surface of the image reading means together with a roller and guides the document to a reading position along the guide surface; and an outer peripheral surface of the conveying roller; Guide surface of the guide member Of those who substantially the same color and a portion to face at least the reading surface.

  The document supplied from the sheet feeding tray and conveyed through the conveyance path is conveyed U-turns by the conveyance roller so as to be reversed along the curved portion. When the curved portion is conveyed, the document is guided to the reading surface of the image reading means by the guide member. The image reading unit reads an image of the document passing through the reading surface. At least two or more members of the outer peripheral surface of the conveying roller and the guide surface of the guide member are opposed to the reading surface of the image reading unit. Here, when the original is thin, a part of the light emitted from the image reading means passes through the original, and the light reflected on the outer peripheral surface and the guide surface affects the read image. Since the members are substantially the same color, a density difference does not occur in the read image as a difference in reflectance between these members.

  Further, according to the present invention, in the image reading apparatus, the guide member is provided with a covering member that covers a gap between the conveyance roller and the guide member at a portion facing the reading surface. As described above, the outer peripheral surface of the conveyance roller and the guide surface of the guide member are opposed to the reading surface of the image reading unit. Here, when the original is thin, a part of the light emitted from the image reading unit passes through the original and is reflected by the outer peripheral surface and the guide surface. Enters the interior without being reflected. Therefore, the difference in the presence or absence of reflected light affects the read image as a density difference. By covering the gap with the covering member, the light that has passed through the document is reflected by the covering member. It is possible to prevent the concentration due to.

  In the image reading apparatus according to the present invention, the covering member is a film material that is attached to the guide surface of the guide member and extends to the outer peripheral surface of the conveying roller or to the vicinity thereof. By using a thin film material for the covering member, the gap can be covered without affecting the guide of the document by the guide member. Further, since the film material has flexibility, it can be deformed so as to be appropriately bent in accordance with the tolerance between the guide member and the conveying roller, and the gap can be reliably covered.

  According to the present invention, in the image reading device, a stepped portion having a radially recessed outer peripheral surface is formed at an edge of the outer peripheral surface of the transport roller, and the tip of the covering member is formed on the stepped portion. It is what was supported. Thereby, since the front-end | tip of a coating | coated member and a conveyance roller overlap, the said clearance gap can be covered completely and reliably. Further, even when the leading end side of the covering member is pushed inward by a document or the like, the stepped portion supports the leading end of the covering member, so that the covering member does not bend or drop inward.

  According to the present invention, in the image reading apparatus, a concave portion is formed on the guide surface on which the covering member is affixed so that the surface of the covering member is recessed from the guide surface. As a result, since the back surface of the document and the covering member are not in close contact with each other, the difference in color between the covering member and the guide member can be reduced from appearing as a density difference in the read image of the document. Accordingly, since the selection range of the color of the covering member is widened, the selection range of the material of the covering member is also widened. Further, by appropriately setting the depth of the recessed portion according to the color of the covering member, the influence of the color of the covering member on the read image of the document can be adjusted. Further, since the covering member is in a position recessed from the guide surface, the covering member does not come into contact with the document guided by the guide member, so that conveyance failure and damage to the covering member due to catching of the document are prevented. In addition, since the depth of the recessed portion can be adjusted according to the thickness of the covering member, it is possible to paste a covering member having a high thickness and high strength.

  According to the present invention, in the image reading apparatus, an inclined surface inclined in a tapered shape toward the recessed portion is formed in a portion of the guide surface facing the reading surface. As a result, the reflected light does not change abruptly at the boundary between the recessed portion and the guide surface, and gradually changes according to the distance between the back surface and the inclined surface of the document. Therefore, also in the read image, the density change at the boundary between the recessed portion and the guide surface becomes gentle, and the influence on the read image can be reduced.

  According to the present invention, in the image reading apparatus, the inclined surface is formed within a range in which a document having a minimum reading width passes through the guide surface. As a result, both ends of the document having at least the minimum reading width are guided to the predetermined positions by the guide surface, and no floating occurs between the both ends of the document and the reading surface of the image reading unit. Further, the guide surfaces around the both ends of the document and the reading surface are maintained at a predetermined distance. Therefore, it is prevented that both ends of the read image become dark.

  As described above, according to the image reading apparatus of the present invention, it is possible to reduce the influence of the conveying roller and the guide member disposed facing the reading surface on the read image as a so-called show-through of the original.

Embodiments of the present invention will be described below with reference to the drawings as appropriate.
FIG. 1 shows an external configuration of a multifunction machine 1 according to an embodiment of the present invention. The multi-function device 1 is a multi-function device (MFD: Multi Function Device) that integrally includes a scanner function, a printer function, and a facsimile function. The upper part of the multifunction device 1 is a scanner unit 2 for reading an image of a document, and the lower part of the multifunction device 1 is a printer unit 3 for recording an image on a recording sheet. The image reading apparatus according to the present invention is realized as the scanner unit 2 of the multifunction machine 1, and the printer function or the like is an arbitrary mechanism in the present invention. For example, the image reading apparatus according to the present invention as a single scanner having only the scanner function. An apparatus may be realized.

Hereinafter, the configuration of the scanner unit 2 will be described in detail.
As shown in FIG. 1, the scanner unit 2 includes a document holding cover 6 having an auto document feeder (ADF) 5 with respect to a reading table 4 that functions as an FBS (Flatbed Scanner). It can be opened and closed through a hinge on the back side. The reading table 4 is configured as a housing of the multifunction machine 1, and a platen glass 20 (see FIGS. 3 and 4) is disposed on the top surface facing the document pressing cover 6. Further, an image reading unit 21 (image reading means) is built in the reading table 4 so as to face the platen glass 20. When the scanner unit 2 is used as an FBS, the document pressing cover 6 is opened to place a document on the platen glass 20, and the document pressing cover 6 is closed to fix the document on the platen glass 20. Thereafter, the image reading unit 21 is scanned along the platen glass 20 to read the image of the original.

  A pressing member 19 made of a sponge, a white plate, or the like is disposed on the lower surface of the document pressing cover 6 in order to press the document placed on the platen glass 20. In the image reading apparatus according to the present invention, the function of the FBS is arbitrary, and the present invention may be realized as an image reading apparatus having only the ADF 5.

  The document pressing cover 6 is provided with an ADF 5 that continuously conveys documents from the paper feed tray 22 to the paper discharge tray 23 via a predetermined conveyance path 26. In the conveyance process by the ADF 5, the document passes through the reading surface 39, and the image reading unit 21 reads the image of the document below the reading surface 39. Details of the structure of the ADF 5 will be described later.

  An operation panel 7 is provided on the front side of the reading table 4. The operation panel 7 includes various operation buttons and a liquid crystal display unit, and the multifunction device 1 operates according to instructions from the operation panel 7. In addition to the instruction from the operation panel 7, the multifunction device 1 also operates according to an instruction connected to the computer and transmitted from the computer via a printer driver, a scanner driver, or the like.

  In addition, a slot portion 8 into which various small memory cards as recording media can be loaded is provided in the upper left part of the front surface of the multifunction device 1. The image data recorded in the small memory card loaded in the slot unit 8 is read out, information about the image data is displayed on the liquid crystal display unit, and an input for recording an arbitrary image on the recording sheet by the printer unit 3 is performed. This can be done from the operation panel 7.

  As shown in FIGS. 1 and 3, the paper feed tray 22 and the paper discharge tray 23 are configured in two upper and lower stages on the document pressing cover 6. The paper feed tray 22 is formed integrally with the upper surface of the document pressing cover 6. A document whose image is read by the ADF 5 is placed on the paper feed tray 22 so that a plurality of sheets are stacked and the front end in the paper feed direction is inserted into the ADF 5. In addition, a pair of document guides 24 are provided on the paper feed tray 22 so as to be slidable in the depth direction across the depth direction of the multifunction machine 1. The document guide 24 stands up from the sheet feed tray 22 and regulates the width direction of the document placed on the sheet feed tray 22, and either one of the pair of document guides 24 by a known interlocking mechanism. Is slid, the other document guide 24 is also slid in the opposite direction.

  That is, when the document width is narrow, if one document guide 24 on the front side of the multifunction machine 1 is slid to the back side, the other document guide 24 on the back side slides to the front side in conjunction with this. Moving. As a result, the document width regulated by the pair of document guides 24 can be reduced with the approximate center in the depth direction as the center. On the contrary, when the document width is wide, when one document guide 24 on the front side of the multifunction machine 1 is slid and moved to the front side, the other document guide 24 on the back side is linked to the back side. By sliding, the original width regulated by the pair of original guides 24 can be increased.

  A paper discharge tray 23 is integrally formed with the pair of document guides 24 so as to be separated from the paper feed tray 22 in the vertical direction. The document discharged from the ADF 5 is held on both sides of the document by the discharge tray 23 and is held in a state separated from the document on the sheet feed tray 22. Since the length of the paper discharge tray 23 in the paper discharge direction is shorter than the length of the document, the front end side of the document in the paper discharge direction is held on the paper feed tray 22 so as to hang down from the paper discharge tray 23. Accordingly, the leading end portion of the document in the paper discharge direction on the paper discharge tray 23 overlaps the rear end portion of the document in the paper feeding direction on the paper feed tray 22, but the leading end portion of the document in the paper feeding direction on the paper feed tray 22. And the rear end portion of the original on the paper discharge tray 23 in the paper discharge direction are held in two stages by the paper discharge tray 23, so that these originals are not confused. Further, by shortening the paper discharge tray 23, a necessary space on the document pressing cover 6 can be reduced, and the multifunction device 1 can be made thin and small.

  In addition, at the end of the paper feed tray 22 on the side where the ADF 5 is not provided, the posture changes between a standing posture standing up from the top surface of the paper feed tray 22 and a lying posture lying down together with the top surface of the paper feed tray 22. A document stopper 25 is provided. As shown in the figure, by placing the document stopper 25 in an upright posture, for example, when a document having the same size as the paper feed tray 22 is discharged from the ADF 5, the document is stopped by the document stopper 25, It is possible to prevent sliding from the paper feed tray 22. In this way, by receiving the discharged document with the document stopper 25, the area of the sheet feed tray 22 can be reduced, and the document pressing cover 6 integrally formed with the sheet feed tray 22 can be downsized. Further, when the document stopper 25 is not necessary, by adopting a lying posture, the multifunction device 1 can be made compact when packed or stored without protruding from the document pressing cover 6.

  As shown in FIGS. 2 and 3, a conveyance path 26 is formed in a substantially U shape in the lateral direction inside the ADF 5 so as to connect the paper feed tray 22 and the paper discharge tray 23. The conveyance path 26 includes an ADF main body 27 formed integrally with the document pressing cover 6 and an ADF cover 28 provided on the ADF main body 27 so as to be freely opened and closed. As shown in FIG. 3, the suction chute 29 of the ADF 5 includes a horizontal plane formed in the ADF main body 27 and a partition plate disposed inside the ADF cover 28 so that the paper feed tray 22 is extended. 30 is configured as a passage having a predetermined width up and down. The conveyance path 26 is formed in a substantially U shape from the suction chute 29 to the paper discharge chute 38 through the curved portion 37, and the curved portion 37 and the paper discharge chute 38 are also formed in the ADF main body 27, A passage having a predetermined width is continuously formed by the ADF cover 28, the partition plate 30, the guide member 42, and the like.

  Conveying means for conveying the document is disposed in the conveying path 26. Specifically, as shown in the figure, the sheet is conveyed by a suction roller 31 and a suction nip piece 32 that is in pressure contact therewith, a separation roller 33 and a separation nip piece 34 that is in pressure contact therewith, and a conveyance roller 35 and a pinch roller 36 that is in pressure contact therewith. Means are configured. The configuration of each roller and nip piece constituting the conveying means is an example, and the number and arrangement of rollers can be changed, or a pinch roller can be used in place of each nip piece, and other known conveying means can be changed. Of course.

  As shown in the figure, the suction roller 31 is provided at the approximate center of the suction chute 29 so that a part of the roller surface is exposed from the upper surface of the horizontal plane formed on the ADF main body 27. . Similarly, the separation roller 33 can be rotated at a position separated from the suction roller 31 in the paper feeding direction so that a part of the roller surface is exposed from the upper surface of the horizontal plane formed in the ADF main body 27. Is provided. Although not shown in the drawing, a driving force from a motor is transmitted to the suction roller 31 and the separation roller 33 so as to be rotationally driven. The suction roller 31 and the separation roller 33 have the same diameter and are rotated at the same peripheral speed. In addition, a one-turn clutch is interposed in the drive transmission to the suction roller 31, and the suction roller 31 can idle for one turn.

  The suction nip piece 32 is provided at a position facing the suction roller 31 of the partition plate 30 so as to be able to swing in a direction in which the suction nip piece 32 contacts and separates from the suction roller 31. The suction nip piece 32 is elastically biased downward by a spring member (not shown), and is pressed against the roller surface of the suction roller 31 without nipping the document. Similarly, the separation nip piece 34 is provided at a position facing the separation roller 33 of the partition plate 30 so as to be able to swing in a direction in which the separation nip piece 34 contacts and separates from the separation roller 33, and is elastically downward by a spring member (not shown). As a result, the roller is pressed against the roller surface of the separation roller 33 without nipping the document. When the original is nipped by the suction nip piece 32 and the separation nip piece 34, the original is pressed against the suction roller 31 and the separation roller 33, and the rotational force of the suction roller 31 and the separation roller 33 is transmitted to the original. .

  The conveyance roller 35 is disposed in a curved portion 37 that is substantially U-shaped in the lateral direction of the conveyance path 26. The conveying roller 35 has an outer diameter such that the roller surface forms part of the curved portion 37. Similarly to the suction roller 31 and the separation roller 33, the transport roller 35 is driven to rotate by receiving a driving force from a motor (not shown).

  Around the conveying roller 35, pinch rollers 36 are provided at three locations. Each pinch roller is elastically biased by a spring piece, is rotatably supported by the ADF main body 27 or the ADF cover 28, and is in pressure contact with the roller surface of the transport roller 35. And if the conveyance roller 35 rotates, it will follow and the pinch roller 36 will also rotate. By these pinch rollers 36, the original is pressed against the conveying roller 35, and the rotational force of the conveying roller 35 is transmitted to the original.

  A paper discharge chute 38 is formed on the downstream side of the conveyance roller 35 in the document conveyance direction. The paper discharge chute 38 is formed between the ADF cover 28 and the partition plate 30 so as to be continuous with the curved portion 37 of the conveyance path 26 constituted by the inner surface of the ADF cover 28 and the conveyance roller 35. . Accordingly, the original supplied from the paper feed tray 22 to the conveyance path 26 is sequentially discharged through the suction chute portion 29, the curved portion 37, and the paper discharge chute portion 38 to the paper discharge tray 23.

  As shown in FIG. 2, the ADF cover 28 is provided so as to be rotatable upward from the suction roller 31 with the paper feed tray 22 side as a rotation shaft. By opening the ADF cover 28, the suction chute portion 29 and the curved portion 37 are opened, and the suction roller 31 and the separation roller 33 are separated from the suction nip piece 32 and the separation nip piece 34. Therefore, by opening the ADF cover 28, it is possible to eliminate a paper jam generated in the transport path 26 and to perform maintenance inside the ADF 5.

  As shown in FIG. 3, a platen glass 20 is disposed on the upper surface of the reading table 4. The platen glass 20 is used to place a document when the scanner unit 2 is used as an FBS, and is a transparent glass plate, for example. One end side of the platen glass 20 reaches the lower side of the conveying roller 35, and also constitutes a reading surface 39 for reading an image using the ADF 5.

  An image reading unit 21 is built in the reading table 4. As shown in FIG. 3, the image reading unit 21 includes a CIS unit 40, a carriage 41, and a scanning mechanism (not shown). The CIS unit 40 is a so-called contact-type image sensor that irradiates a document with light and converts the reflected light from the document into an electrical signal. The width direction is arranged with the reading direction as the reading direction. The CIS unit 40 is mounted on a carriage 41 and is in close contact with the platen glass 20. The carriage 41 is provided so as to be able to scan below the platen glass 20 by a scanning mechanism (not shown). When the scanner unit 2 is used as an FBS, the carriage 41 is scanned below the platen glass 20, so that the CIS unit 40 reads an image of a document placed on the platen glass 20. On the other hand, when the ADF 5 is used, as shown in the figure, the carriage 41 moves below the reading surface 39 and stops, and the CIS unit 40 reads an image of the document passing through the reading surface 39.

  In the present embodiment, since the scanner unit 2 is also used as an FBS, the image reading unit 21 can be scanned along the platen glass 20, but the FBS is an arbitrary function. When the invention is realized as an image reading apparatus that reads an image using only the ADF 5, the image reading unit 21 may be installed at a position opposite to the conveying roller 35, and a scanning mechanism is unnecessary. In the present embodiment, the close contact type CIS unit 40 is used as the image reading unit 21, but other known image reading units such as a reduction optical system CCD unit may be used. It is.

  A guide member 42 is disposed on a guide surface on the inner side of the curved portion 37 of the transport path 26 and facing the reading surface 39. The guide member 42 is for guiding a document conveyed on the conveyance path 26 to the reading position 39, and is provided on both sides of the conveyance path roller 35 as shown in FIGS. That is, at the position facing the reading surface 39, the transport roller 35 is disposed substantially at the center, and the guide members 42 are disposed on both sides thereof.

  As shown in FIG. 4, the guide member 42 includes a shaft support portion 43 of the transport roller 35 and a guide portion 44 that forms a guide surface of the transport path 26, and each shaft support portion 43 of the pair of guide members 42 transports the guide member 42. The roller 35 is pivotally supported from both sides. The guide portion 44 is formed in a downwardly convex arc shape, and the outer surface thereof forms a guide surface inside the curved portion 37.

  As shown in FIG. 5, the conveyance roller 35 and a part of the guide member 42 are exposed on the lower surface of the document pressing cover 6, and the exposed portion faces the reading surface 39 of the reading table 2. . Thus, the outer peripheral surface of the conveying roller 35 facing the reading surface 39 and the guide surface of the guide member 42 are substantially the same color. The roller surface of the conveying roller 35 is made of a synthetic resin such as EPDM (Ethylene Propylene Diene Methilene Linkage), while the guide member 42 is a synthetic resin such as ABS (Acrylonitrile Butadiene Styrene). These resins are made of substantially the same color or are applied with the same color paint. The color is not necessarily limited, but white is preferable because it can be used as a reference member for the chromaticity and luminance of the CIS unit 40.

  As shown in FIG. 6, a gap 45 is provided between the conveyance roller 35 and the guide member 42. As described above, in order to rotatably support the shaft of the transport roller 35 by the shaft support portion 43 of the guide member 42, an appropriate play is required in the axial direction. Tolerances need to be considered. Therefore, a gap 45 exists between the conveyance roller 35 and the guide member 42, but a film material 46 is stuck on the guide surface of the guide member 42 so as to cover the gap 45.

  The film material 46 is an elastically deformable synthetic resin such as PET (Polyetylene Terephthalate). The film material 46 has at least a width corresponding to the reading surface 39 and has a length that can extend from the center side end of each guide member 42 to the outer peripheral surface of the transport roller 35. is there. On the other hand, constraining members 47 having a slightly smaller diameter than the outer shape of the conveying roller 35 are disposed concentrically at both ends of the outer peripheral surface of the conveying roller 35 in the axial direction. The restraining member 47 is a disk-like member for restraining the torsion of the conveying roller 35 in the circumferential direction. The outer peripheral surface of the restraining member 47 forms a stepped portion 48 that is recessed in the radial direction at the edge of the outer peripheral surface of the conveying roller 35. The leading end of the film material 46 extends to reach the stepped portion 48 and is supported so as to contact the outer peripheral surface of the restraining member 47. A gap 45 between the conveyance roller 35 and the guide member 42 is covered with respect to the reading surface 39 by the film material 46 thus provided.

  A concave portion 49 in which the guide surface is recessed is formed at the end on the center side of the guide member 42 to which the film material 46 is stuck. More specifically, as shown in FIGS. 7 and 8, the guide surface 50 that faces the reading surface 39 among the guide surfaces of the guide member 42 forms a plane substantially parallel to the reading surface 39. Guided by the guide surface 50, the document is conveyed in close contact with the reading surface 39. The guide surface 50 is formed as a substantially horizontal plane parallel to the reading surface 39 at the end side of each guide member 42, that is, the end portion that does not face the conveyance roller 35.

  On the other hand, a concave portion 49 that is recessed by a depth L in the direction away from the reading surface 39 is formed at the center side, that is, the end portion facing the conveyance roller 35. The recessed portion 49 is a space for attaching the film material 46 and is formed according to the size of the film material 46. The depth L of the recessed portion 49 is also designed according to the thickness of the film material 46, and when the film material 46 is attached to the recessed portion 49, the depth L is The depth is such that the surface is somewhat recessed from the guide surface 50. The thickness of the film material 46 is set in accordance with the material so that required flexibility and strength are realized in consideration of required durability strength and the like.

  An inclined surface 51 is formed from the recessed portion 49 to the guide surface 50. Specifically, as shown in the figure, the guide surface 50 that forms the lower surface of the guide member 42 gradually moves from a predetermined position toward the recessed portion 49 toward the recessed portion 49 in a direction away from the reading surface 39 to the recessed depth L of the recessed portion 49. In the longitudinal section in the document width direction shown in FIG. 7, the inclined surface 51 has a different distance from the reading surface 39. As shown in FIG. 5, the inclined surface 51 is formed corresponding to a document having a minimum reading width capable of reading an image using the ADF 5 of the scanner unit 2. The ADF 5 is a so-called center register that conveys a document with the center in the width direction as a reference, and as shown in FIG. 5, the inclined surface 51 is within the range of the minimum reading width W with the center in the width direction as a reference. Is formed.

  In other words, the guide surfaces facing the reading surfaces 39 of the respective guide members 42 are all formed with guide surfaces 50 outside the minimum reading width W, and gradually enter the minimum reading width W and the guide surfaces 50 gradually enter. An inclined surface 51 that is concaved to a concave portion 49 with a concave depth L in the vicinity of the conveying roller 35.

Hereinafter, an image reading operation of a document using the ADF 5 will be described.
When an image is read by the scanner unit 2 using the ADF 5, the document pressing cover 6 is closed with respect to the reading table 4 as shown in FIG. Then, a document to be read is placed on the paper feed tray 22. The document may be one sheet or a plurality of sheets. For example, when reading images of a plurality of originals of the same size, the originals are stacked and aligned, and one end thereof is inserted into the suction chute portion 29 from the paper feed tray 22.

  As shown in FIG. 3, the document inserted into the suction chute 29 first comes into contact with the suction roller 31 and the suction nip piece 32. As described above, since the suction roller 31 can idle for one round, the original is inserted further into the back while the suction roller 31 is idle and the suction nip piece 32 is retracted against the elastic force of the spring member. it can. The leading edge of the document comes into contact with the separation roller 33 and the separation nip piece 34. Due to this contact, a feeling of resistance occurs in the insertion of the document, and the user determines that the insertion of the document has been completed. The original is placed on the paper feed tray 22 with the leading end inserted into the suction chute 29, whereby the setting of the original is completed.

  Next, the user operates the operation panel 7 to instruct the multifunction device 1 to start reading an image of a document. The operation panel 7 is provided with, for example, a start button. By pressing the start button, the multifunction device 1 can be instructed to start image reading. In response to the instruction, the control unit (not shown) of the multifunction machine 1 drives the motor to rotationally drive the suction roller 31, the separation roller 33, and the conveyance roller 35 at a predetermined timing. Further, the carriage 41 is moved to position the CIS unit 40 below the reading surface 39. At this time, the CIS unit 40 emits light from the light source and adjusts the chromaticity and luminance with reference to the guide surface of the guide member 42.

  As the suction roller 31 rotates, the document that is in pressure contact with the suction roller 31 by the biasing force of the suction nip piece 32 is sent out in the transport direction. A plurality of documents are integrally urged toward the suction roller 31 side by the suction nip piece 32, and the lowermost document in contact with the roller surface of the suction roller 31 receives the rotational force of the suction roller 31 to convey in the transport direction. Sent out. As a result, the leading edge of the document enters between the separation roller 33 and the separation nip piece 34 and is nipped therebetween. The original is pressed against the roller surface of the separation roller 33 by the separation nip piece 34, receives the rotational force of the separation roller 33, and is further fed out in the conveyance direction. When the lowermost document is sent out by the suction roller 31, due to the influence of static electricity or the like, the originals stacked thereon may be sent out so as to overlap each other. However, the separation roller 33 and the separation nip piece 34 may be sent. Even if a plurality of originals enter between them, only the lowermost original receives the rotational force of the suction roller 31 and the separation roller 33, so that only the original is separated from the plurality of originals and conveyed. It is sent to the road 26.

  The document fed in this way is guided by the conveyance path 26 and conveyed downward toward the reading surface 39. That is, the original is nipped by the conveyance roller 35 and the pinch roller 36 disposed immediately downstream of the separation roller 33, and is conveyed to the reading surface 39 by receiving the rotational force of the conveyance roller 35. In the conveyance path 26 where the leading edge of the document reaches the reading surface 39, the leading edge of the document is detected by a lead sensor (not shown), and the amount of the encoder or the number of steps of the motor that inputs the rotational force to the conveyance roller 35 is detected. It is determined that the tip has reached the reading surface 39. When the leading edge of the document reaches the reading surface 39, the CIS unit 40 starts reading an image of the document that passes through the reading surface 39.

  The original is further conveyed while the image is read by the CIS unit 40, the leading end side of the original is nipped between the conveying roller 35 and the pinch roller 36 immediately downstream of the reading surface 39, and the trailing end side of the original is the conveying roller. In a state of being nipped between the pin 35 and the pinch roller 36 immediately upstream of the reading surface 39, the U-turn is conveyed so as to be reversed along the curved portion 37 by receiving the rotational force of the conveying roller 35. During this time as well, the CIS unit 40 reads the image of the document passing on the reading surface 39. The read sensor detects the trailing edge of the document, and it is determined that the trailing edge of the document has reached the reading surface 39 based on the encoder amount or the number of steps of the motor that inputs the rotational force to the conveying roller 35. When the trailing edge of the original passes through the reading surface 39, the image reading by the CIS unit 40 is finished, and the original is discharged from the discharge chute 38 to the discharge tray 23.

  Thus, the CIS unit 40 reads the image of the document passing on the reading surface 39. However, as shown in FIG. 4, the curved portion 37 of the conveyance path 26 is located at a position facing the reading surface 39. Since the guide member 42 is provided, the document on which image reading is performed is guided by the guide member 42 and reaches the reading surface 39. As shown in FIG. 5 to FIG. 8, a recessed portion 49 is formed at an end portion on the center side of the guide member 42, and an inclined surface 51 inclined in a tapered shape is formed on the recessed portion 49. Is recessed in a direction away from the reading surface 39 from the guide surface 50 that guides the document in close contact with the reading surface 39. However, since the concave portion 49 and the inclined surface 51 are formed inside the minimum reading width W, both ends of the document are always guided by the guide surface 50 so as to be in close contact with the reading surface 39. Therefore, there is no floating between the both ends of the document and the reading surface 39, and the guide surface 50 faces the reading surface 39 in the vicinity of both ends where the document does not pass. Will not darken.

  The CIS unit 40 emits light to a document passing through the reading surface 39 and reads an image with reflected light from the document. If the document is thin, a part of the light from the CIS unit 40 is read. Passes through the document. In the width direction of the document on which the reading surface 39 extends, as shown in FIG. 5, a conveying roller 35 is disposed in the center facing the reading surface 39, and guide members 42 are disposed on both sides thereof. Yes. Therefore, the light transmitted through the document hits and reflects the roller surface of the conveying roller 35 at the center, and hits and reflects the guide surface of the guide member 42 on both sides thereof. As described above, since the roller surface of the transport roller 35 and the guide surface of the guide member 42 are substantially the same color, the reflectance of these members is approximately the same. Therefore, a density difference does not occur in the read image as a difference in reflectance between the conveyance roller 35 and the guide member 42.

  Further, as shown in FIG. 6, there is a gap 45 between the conveying roller 35 and the guide member 42. Here, if the film material 46 does not exist, the light transmitted through the document enters the ADF 5 from the gap 45, so that no reflected light is generated from the position corresponding to the gap 45, and the light is transmitted to the CIS unit. It will not return. On the other hand, since reflected light is generated from the transport roller 35 and the guide member 42, this difference appears as a density difference in the read image, but the gap 45 is covered with a film material 46 as shown in the figure. Therefore, the light that has passed through the document and reached the position corresponding to the gap 45 hits the film material 46 and is reflected, and the reflected light returns to the CIS unit 40. Thereby, the density difference of the read image due to the gap 45, that is, the occurrence of show-through is prevented.

  As shown in the drawing, the film material 46 is extended until it contacts the outer peripheral surface of the transport roller 35. However, since the film material 46 is elastically deformed to a suitable degree, Even if the size of the gap 45 slightly changes due to tolerance or the like, the gap 45 can be reliably covered by being deformed so as to bend appropriately according to the change. Further, since the leading end of the film material 46 is supported by the stepped portions 48 formed on both end sides in the axial direction of the conveying roller 35, the leading end of the film material 46 falls inward even if a slight external force is applied. Will not bend or bend.

  In this way, the covering member covering the gap 45 is realized by, for example, projecting the end portion on the center side of the guide member 42 so as to extend the guide surface, in addition to the flexible member such as the film material 46. However, in consideration of contact with the conveyance roller 35 and replacement due to wear or breakage, it is preferable to attach another member such as the film material 46 to the guide member 42.

  By sticking the film material 46 to the guide member 42, a convex portion is formed on the guide surface of the guide member 42 by the thickness, but as shown in FIGS. 7 and 8, the guide member A concave portion 49 is formed at the position where the film material 46 is affixed to 42, that is, at the end on the center side, and the concave depth L of the concave portion 49 is sufficiently deeper than the thickness of the film material 46. It is. Therefore, the surface of the film material 46 is in a position recessed from the guide surface 50 that guides the document so as to be in close contact with the reading surface 39. The guide surface 50 has both ends of the document in close contact with the reading surface 39, and the central portion of the document is also in close contact with the reading surface 39 by being substantially in the same position as the guide position of the guide surface 50 due to the tension of the document itself. . Further, since the conveyance roller 35 exists in the center portion of the document, it is always located on the reading surface 39 side with respect to the film material 46 supported by the stepped-down portion 48. Accordingly, the document guided by the guide member 42 floats from the film material 46 and does not come into contact with the film material 46. Thereby, conveyance failure and damage to the film material 46 due to catching of the document are prevented.

  Further, since the back surface of the document and the film material 46 are not in close contact with each other, the difference in color between the film material 46 and the guide member 42 can be reduced from appearing as a density difference in the read image of the document. In general, as the distance from the back of the original increases, the influence of the color of the member decreases. Therefore, the recess depth L of the recess 39 is appropriately set according to the color difference between the color of the film material 46 and the guide member 42. Thus, the influence of the color of the film material 46 on the read image of the original can be adjusted.

  Of course, it is preferable that there is no color difference between the film material 46 and the guide member 42, but within the range that can be adjusted by the depth L of the recessed portion 39, there is a degree of freedom in selecting the material and color in consideration of cost and the like. spread. Further, since the selection range is widened in the thickness of the film material 46, the film material 46 can be made relatively thick according to the required strength.

  Further, the depth L of the recess, which is the difference between the recessed portion 39 and the guide surface 50, is gradually changed in a tapered shape by the inclined surface 51 as shown in FIGS. That is, the distance from the back surface of the document does not change abruptly at the boundary between the recessed portion 39 and the guide surface 50 but by the inclined surface 51 formed between them. Although there is a slight difference between the reflected light from the film material 46 affixed to the recessed portion 39 and the reflected light from the guide surface 50 depending on the depth L of the dent and the color of the film material 46, such reflected light. The difference does not occur abruptly, but gradually changes according to the change in the distance between the inclined surface 51 and the back side of the document. Therefore, also in the read image, the density change due to the difference in the reflected light at the boundary between the recessed portion 39 and the guide surface 50 becomes moderate, and the influence of the difference on the read image can be reduced.

  As described above, according to the multifunction device 1 according to the present embodiment, the conveyance roller 35 and the guide member 42 disposed to face the reading surface 39 have an influence on the read image as a so-called document show-through. Can be reduced. In addition, this embodiment is only an example of this invention, and it cannot be overemphasized that embodiment can be changed suitably in the range which does not change the summary of this invention.

FIG. 1 is a perspective view showing an external configuration of a multifunction machine 1 according to an embodiment of the present invention. FIG. 2 is a perspective view showing an external configuration of the multifunction machine 1 with the ADF cover 28 opened. FIG. 3 is a cross-sectional view taken along the line AA showing the main configuration of the ADF 5. FIG. 4 is a BB cross-sectional view showing the main configuration of the ADF 5. FIG. 5 is a partial bottom view showing the configuration around the position where the reading surface 39 of the document pressing cover 6 faces. FIG. 6 is a partially enlarged bottom view showing a configuration around the position where the reading surface 39 of the document pressing cover 6 faces. FIG. 7 is a cross-sectional view taken along the line C-C showing the configuration of the guide member 42. FIG. 8 is a DD cross-sectional view showing the configuration of the guide member 42. FIG. 9 is a diagram showing a schematic configuration of a conventional image reading apparatus.

Explanation of symbols

1 ... Multifunction machine (image reading device)
21... Image reading unit (image reading means)
DESCRIPTION OF SYMBOLS 22 ... Paper feed tray 23 ... Discharge tray 26 ... Conveyance path 35 ... Conveyance roller 37 ... Curve part 42 ... Guide member 46 ... Film material (covering member)
48 ... Stepped portion 49 ... Recessed portion 50 ... Guide surface 51 ... Inclined surface

Claims (7)

A paper feed tray and a paper discharge tray arranged in two upper and lower stages;
A conveyance path formed in a substantially U shape in a lateral direction so as to connect the paper feed tray and the paper discharge tray;
Transport means for transporting a document from the paper feed tray to the paper discharge tray via the transport path;
A conveyance roller disposed in a substantially U-shaped curved portion of the conveyance path and configured to convey the document so as to be reversed along the curved portion;
An image reading means disposed at a position facing the conveying roller and reading an image of a document conveyed in the predetermined direction along the conveying path at a predetermined reading position;
A guide member which is provided opposite to the reading surface of the image reading unit together with the conveying roller and guides the document to the reading surface along the guide surface;
An image reading apparatus in which an outer peripheral surface of the conveying roller and at least a portion of the guide surface of the guide member facing the reading surface are substantially the same color.   The image reading apparatus according to claim 1, wherein the guide member is provided with a covering member that covers a gap between the conveyance roller and the guide member at a portion facing the reading surface.   The image reading apparatus according to claim 2, wherein the covering member is a film material that is affixed to a guide surface of the guide member and extends to the outer peripheral surface of the transport roller or to the immediate vicinity thereof.   4. The step according to claim 3, wherein a stepped portion having an outer peripheral surface recessed in a radial direction is formed at an edge of the outer peripheral surface of the transport roller, and the tip of the covering member is supported by the stepped portion. Image reading device.   5. The image reading apparatus according to claim 3, wherein the guide surface on which the covering member is affixed is provided with a recessed portion that causes the surface of the covering member to be recessed from the guide surface.   The image reading apparatus according to claim 5, wherein an inclined surface inclined in a tapered shape toward the recessed portion is formed in a portion of the guide surface that faces the reading surface. The image reading apparatus according to claim 6, wherein the inclined surface is formed within a range in which a document having a minimum reading width passes through the guide surface.

Images