JP6312432B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus, and more particularly to an image reading apparatus provided with an automatic document conveyance mechanism.

  2. Description of the Related Art Conventionally, image reading apparatuses such as digital copying machines, facsimiles, and image scanners are often provided with a document conveying device that feeds out a plurality of documents one by one and automatically conveys them to a reading position. Furthermore, image reading apparatuses that can simultaneously read both sides of a conveyed document have been widely put into practical use.

  As an image reading apparatus capable of simultaneous reading on both sides, two image reading units along the document conveying path are placed on opposite sides of a document conveying surface made of platen glass (also referred to as contact glass), on both sides of a document to be passed. The thing arrange | positioned so that each may face is known (for example, refer patent document 1). In this case, a contact image sensor (CIS) that is advantageous for downsizing the entire apparatus is often used for the image reading unit.

  On the other hand, recently, not only thin originals such as plain paper but also credit cards, cash cards, various membership cards and certificates, plastic or cardboard laminates, resin or metal cards, etc. Therefore, it is required to perform image reading processing on a thick original. However, if the depth of focus of the CIS is small, when the thickness of the document changes, it may not be possible to accurately read the image of the document passing through the document conveyance surface on the side opposite to the document conveyance surface. There is.

  In view of this, the double-sided image reading device described in Patent Document 1 includes a pair of image reading units that are disposed at positions facing both sides of the conveyed document and at least one of which can be moved close to and away from the document. The movement of one of the image reading means is controlled by detecting the thickness of the conveyed document, thereby adjusting the interval of the image reading means relative to the document so that it can be read accurately even if the thickness of the document changes. ing.

  Further, in order to read the image surfaces of the sheet materials having different thicknesses well, there is known an image reading apparatus that holds the image reading unit movably up and down while urging the image reading unit toward the sheet conveying surface ( For example, see Patent Document 2). In this image reading apparatus, the image reading unit or the sheet conveyance guide is moved up and down by the balanced movement mechanism or the balanced link mechanism so that the image reading gap between the image reading unit and the sheet conveying surface is maintained substantially the same as the thickness of the document. I have to.

JP 2002-262029 A Japanese Patent No. 431660

  However, the double-sided image reading apparatus described in Japanese Patent Laid-Open No. 2004-228561 is moved up and down by rotating the image reading means made of CIS by a piezoelectric actuator based on the thickness of the original or by rotating a fixed pitch screw with a pulse motor. Adjust the interval. At this time, since the CIS does not directly contact or engage with the document guide surface of the glass supporting the document, the document conveyance gap between the document guide surface and the document guide surface is determined only by the amount of elevation of the CIS. For this reason, the distance from the CIS document becomes unstable, and it may be difficult to accurately and reliably read the image of the document.

  Further, in the image reading apparatus described in Patent Document 2, the image reading gap is changed by the image reading unit being pushed up when the pair of rollers arranged on the upstream side and the downstream side nip the original. For this reason, the height of the image reading unit tends to become unstable, the image reading gap fluctuates, and images cannot always be read accurately and reliably, which may cause problems such as deterioration or deterioration in image reading accuracy. .

  Accordingly, the present invention has been made to solve the above-described conventional problems, and an object of the present invention is to provide an image reading unit and an original conveying surface in an image reading apparatus that reads an image of an original conveyed on an original conveying surface. Can be set to an appropriate height constantly and stably corresponding to the thickness of the document, thereby achieving high reading accuracy that can always perform image reading accurately and reliably. It is to be realized.

The image reading apparatus of the present invention, for reading the document conveying surface having been reading position along the document transport path which a document is conveyed, the image of the document conveyed along the document conveying surface, said original conveying surface a and an image reading portion disposed facing the image reading unit is movable in the width direction crossing the conveying direction of the document to the document transport surface, the image reading in the width direction part from has a protrusion of at least one pair is protruded toward the document transport surface, the document conveying surface has a contact surface for receiving the protruding portion of the pair of the image reading unit, gap between said image reading portion and the original conveying surface, at least a length different first gap, the width direction to the second gap, the image reading unit with respect to the original conveying surface the position moved to the abutment to abut on the protruding portion Wherein the height or at least one of the protrusion height of the protrusion of the changes.

  In this way, by directly contacting the protruding portion of the image reading unit and the contact surface of the document conveyance surface, the conveyance gap between the image reading unit through which the document passes and the document conveyance surface is reduced in the width direction of the image reading unit. Not only is the image reading unit moved in the width direction with respect to the document conveyance surface, but also suitable for the thickness of the document passing through the conveyance gap. The height can be changed. As a result, images can always be accurately and clearly read from various originals with different thicknesses, from thin originals such as plain paper to thick originals such as credit cards.

  Note that when the document conveying surface is made of platen glass (or contact glass), it means platen glass (or contact glass) itself in a narrow sense, and platen glass (or contact glass) in a broad sense. It is understood to mean a structure including a frame portion to be held. In this specification, the document conveyance surface is used in a broad sense.

  In an embodiment, the image reading unit further includes means for urging the image reading unit toward the contact surface of the document conveying surface. As a result, it is possible to more stably ensure the conveyance gap at an appropriate height while accommodating different document thicknesses.

  In one embodiment, the contact surface is provided at a height different from the document conveyance surface and the document conveyance surface. As a result, the height of the conveyance gap can be changed in two steps, with one height when the protruding portion of the image reading unit directly contacts the document conveyance surface that supports the document to be conveyed.

  In this case, in one embodiment, the contact surface is provided at the document conveyance surface and a plurality of heights that are stepwise different from the document conveyance surface. Thereby, the height of the conveyance gap can be changed in three or more stages.

  In one embodiment, a contact surface having a height different from that of the document conveyance surface is provided on the protrusion of the document conveyance surface. Such an abutting surface can be easily provided, for example, by attaching a separate protruding member to the document conveying surface.

  In another embodiment, a contact surface having a height different from that of the document conveying surface is provided in the recessed portion of the document conveying surface. Such a contact surface can be easily provided by forming a recess in the frame portion of the document conveying surface, for example.

  In one embodiment, the protrusion height of the protrusion of the image reading unit changes in accordance with the amount of movement of the image reading unit in the width direction. This makes it possible to adjust and control the protrusion height of the protrusion in a one-dimensional manner, so that it becomes easy to adjust the height of the conveyance gap.

  In this case, in one embodiment, the protrusion of the image reading unit is an eccentric roller having a rotation center axis in the document conveyance direction. Accordingly, it is possible to adjust the height of the conveyance gap steplessly by changing the protrusion height of the protrusion portion steplessly.

  In another embodiment, a driving unit for moving the image reading unit in the width direction is further provided, and the driving unit is driven and controlled in accordance with the thickness of the document. As a result, the height of the conveyance gap can be automatically adjusted to continuously convey and read documents having different thicknesses.

It is sectional drawing which shows the suitable embodiment of the image reading apparatus of this invention. It is a front view of the image reading part of the 1st embodiment of the present invention. FIGS. 2A and 2B are partial enlarged views of FIG. (A), (B) figure is the elements on larger scale corresponding to FIG. 3 after a height fluctuation. (A), (B) figure is the elements on larger scale of the modification of a 1st embodiment, respectively. (A), (B) figure is the elements on larger scale corresponding to FIG. 5 after a height fluctuation. It is a front view of the image reading part of the 2nd embodiment of the present invention. (A)-(C) figure is the elements on larger scale which show the height fluctuation | variation in a 2nd embodiment.

  Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are denoted by the same or similar reference numerals. Further, in the following description, a flexible original that can be folded like plain paper is referred to as a sheet original, and a hard and inflexible original such as a resin or metal card is referred to as a card original for convenience.

  FIG. 1 is a cross-sectional view showing a preferred embodiment of an image reading apparatus having an automatic document feed (ADF) function. The image reading apparatus 1 according to this embodiment can be used for both sheet originals and card originals, and is configured to read images on both the front and back sides of the original. The image reading apparatus 1 includes a lower unit 2 and an upper unit 3 constituting an ADF attached to the lower unit so as to be opened and closed.

  The lower unit 2 is provided with a first platen glass 4 on the upper surface thereof, and a first image reading unit 5 for reading the lower surface of the document passing over the first platen glass 4 is disposed immediately below the first platen glass 4. Yes. The first image reading unit 5 is a CIS provided with a lighting device, a rod lens array, and a light receiving sensor in a housing 6. The first image reading unit 5 is mounted on the carriage so as to be horizontally movable in order to scan and read a document on a placed document reading platen adjacent to the first platen glass 4.

  In the upper unit 3, a second image reading unit 7 is disposed so as to face the first image reading unit 5 with the first platen glass 4 of the lower unit 2 interposed therebetween. Similarly, the second image reading unit 7 is a CIS provided with a lighting device, a rod lens array, and a light receiving sensor in a housing 8, and a second platen glass 9 is provided on the lower surface of the housing 8.

  Further, the upper unit 3 includes a paper feed tray 10 for stacking and placing a plurality of sheet originals S, an ADF main body 11 that carries out image reading processing by conveying sheet originals from the paper feed tray, and reading processing. And a paper discharge tray 12 for discharging and storing the sheet original. Inside the ADF main body 11, a first document conveyance path for folding a sheet document from the sheet feed tray 10, passing through a conveyance gap G between the first and second image reading units 5 and 7, and conveying the sheet document to the discharge tray 12. 13 is provided.

  In the first document transport path 13, a feeding roller 14 for contacting the uppermost sheet document S on the paper feed tray 10 and feeding the sheet document S to the first document transport path is disposed on the most upstream side. ing. Immediately downstream thereof, a sheet separation mechanism is provided that includes a sheet feeding roller 15 that reliably separates the fed sheet originals one by one and a separation pad 16 that abuts the sheet feeding roller 15.

  Further, on the first document transport path 13, a pair of first read rollers 17 for transporting a sheet document to a reading position is provided upstream of the first and second image reading units. A pair of second lead rollers 18 for sending the sheet document in the discharge direction are disposed downstream of the image reading unit. A discharge roller 19 for discharging the sheet document to the discharge tray 12 is disposed at the end of the first document transport path 13.

  On the end surface of the upper unit 3 opposite to the paper feed tray 10, a card document feed port (not shown) that opens near the lower end of the upper unit 3 and a plurality of card documents C are placed in succession. A card feed guide (not shown) is provided. Inside the ADF main body 11, a card document passes through a conveyance gap G between the first and second image reading units 5 and 7 from the card feeding guide and is conveyed to the paper discharge tray 12. A second document transport path 20 is provided. A third lead roller 21 and a fourth lead roller 22 are disposed immediately upstream and downstream of the first and second image reading units 5 and 7 along the second document conveyance path 20.

  A feeding roller (not shown) for contacting the uppermost card document C in the card feeding guide and feeding the card document C to the second document conveying path is located upstream of the second document conveying path 20. ) Is arranged. Furthermore, a card separation mechanism is provided that reliably separates card documents one by one from the card feeding guide, for example, a sheet feeding roller and a separation roller that contacts the sheet feeding roller. Since each of these rollers is composed of a known structure used in a conventional ADF, it will be omitted for convenience of explanation in the accompanying drawings.

  FIG. 2 shows the document conveying surface 24 composed of the first platen glass 4 and its frame portion and the second image reading unit 7 from the upstream side in the document conveying direction as described above. FIGS. 3A and 3B are partially enlarged views of the vicinity of the left and right ends in the width direction perpendicular to the document conveyance direction of the second image reading unit 7 of FIG.

  As shown in each of these drawings, a pair of protrusions 25a and 25b having the same height are integrally provided on the lower surface of the second image reading unit 7 at both left and right ends. The second image reading unit 7 is disposed with both projecting portions 25 a and 25 b abutting against the document conveying surface 24, thereby increasing the height between the image reading surface on the lower surface of the second image reading unit 7 and the document conveying surface 24. A constant conveyance gap G is defined over the entire length in the width direction of the second image reading unit.

  As shown in FIG. 2, the second image reading unit 7 can be biased toward the document conveying surface 24 by providing an appropriate biasing means such as a spring 36 on the fixed support unit 37 as shown in FIG. 2. . Accordingly, since the projecting portions 25a and 25b are always brought into contact with the document transport surface 24 with a certain amount of pressing force, a transport gap G having a certain height is secured, which is convenient. This height conveyance gap G is set so as to be suitable for image reading of a thin document such as a sheet document.

  The second image reading unit 7 can be moved in the width direction by one of the width directions by the driving means 26 arranged on the left side in the drawing in this embodiment. As the driving means 26, for example, an actuator composed of a pulse motor or an electromagnetic solenoid can be used.

  A pair of protrusions 27 a and 27 b are provided on the document conveying surface 24 at equal distances on the same side of the protrusions 25 a and 25 b along the movement direction of the second image reading unit 7 in the width direction. ing. In the present embodiment, the protrusions 27a and 27b are arranged on the left side of the protrusions 25a and 25b in the figure, but can also be provided on the right side.

  As shown in FIGS. 3A and 3B, the protrusions 27a and 27b are flat and horizontal of a sufficiently large size so that the protrusions 25a and 25b of the second image reading unit 7 can be brought into contact with the upper surfaces thereof. The contact surfaces 28a and 28b have the same height. The side surfaces adjacent to the protrusions 25a and 25b of the protrusions 27a and 27b are formed on a relatively gentle slope. The protrusions 27a and 27b can be easily provided by sticking a separate member having a desired shape and size to the document conveying surface 24, for example.

  According to this embodiment, the second image reading unit 7 is moved to the left in the drawing along the width direction by the driving means 26, and the projecting portions 25a and 25b are moved to the inclined surfaces of the document conveying surface 24 and the projections 27a and 27b. Are arranged on the contact surfaces 28a and 28b as shown in FIGS. 4 (A) and 4 (B). Thereby, the conveyance gap G can be changed higher than the case of FIG. The conveyance gap G1 thus increased is set so as to be suitable for image reading of a thick original such as a card original.

  In the modification of the first embodiment, the protrusion on the document conveying surface 24 can be provided so as to have two contact surfaces with different heights in a stepwise manner. As a result, when the second image reading unit 7 is moved by a predetermined distance to the left in the drawing along the width direction by the driving means 26, the protrusions 25a and 25b are brought into contact with the lower abutment surface of the protrusion. When it is arranged above and is further moved to the left in the figure by a short distance, it is arranged on the higher contact surface of the projection.

  Accordingly, the conveyance gap between the second image reading unit 7 and the document conveyance surface 24 can be changed in three stages. Furthermore, by providing three or more contact surfaces with different heights on the protrusions on the document conveying surface 24, the conveying gap can be further changed in multiple stages.

  5A and 5B show a modification of the first embodiment of FIG. In this modification, the pair of left and right protrusions 29 a and 29 b provided in the second image reading unit 7 has a protrusion height larger than that in FIG. 3, and the document conveying surface 24 has protrusions 27 a and 27 b. Instead, a pair of left and right recessed portions 31 a and 31 b are provided in the frame portion 30 that constitutes a part of the document conveying surface 24. The recessed portions 31a and 31b have flat and horizontal abutting surfaces 32a and 32b having a sufficient size for abutting the protruding portions 29a and 29b of the second image reading unit 7 on the bottom surfaces thereof.

  As shown in FIGS. 5A and 5B, when the projecting portions 29a and 29b of the second image reading unit 7 are arranged on the contact surfaces 32a and 32b of the recessed portions 31a and 31b, the second image reading unit 7 is provided. A conveying gap G having a certain height is defined between the document conveying surface 24 and the document conveying surface 24 over the entire length in the width direction of the second image reading unit. The transport gap G is preferably set so as to be suitable for image reading of a thin original such as a sheet original, as in FIG.

  The concave portions 31a and 31b are formed on one side surface in the width direction, in the present embodiment, on the left side surface in the figure on a relatively gentle slope. When the second image reading unit 7 is moved to the left in the drawing along the width direction by the driving means 26, the projecting portions 29a and 29b slide along the inclined surfaces of the recessed portions 31a and 31b, as shown in FIG. As shown in (A) and (B), they are arranged on the document conveying surface 24. Thereby, the said conveyance gap can be changed higher than the case of FIG. The conveyance gap G2 thus increased is set so as to be suitable for image reading of a thick original such as a card original.

  FIG. 7 shows the second image reading unit 7 and the document conveying surface 24 of the second embodiment of the present invention from the upstream side in the document conveying direction as in FIG. The second image reading unit 7 according to the second embodiment includes rolling rollers 33a and 33b arranged at both left and right ends in the width direction.

  The rolling rollers 33a and 33b are provided so that a part of the rolling rollers 33a and 33b protrudes from the lower surface of the second image reading unit 7 toward the document conveying surface 24 and the protruding height is the same on the left and right. Accordingly, similarly to the first embodiment of FIG. 2, a conveyance gap having a constant height is provided between the second image reading unit 7 and the document conveyance surface 24 over the entire length in the width direction of the second image reading unit. Defined.

  8A to 8C illustrate one of the rolling rollers, that is, the rolling roller 33b on the right side in the drawing. As shown in the figure, the rolling roller 33b is an eccentric roller provided on a circular roller body 34b with the rotation center shaft 35b shifted from its center position. In addition, since the left side rolling roller 33a is comprised similarly to the right side rolling roller 33b, and is attached in the same eccentric position in a figure, detailed drawing is abbreviate | omitted.

  In the second embodiment, the conveyance gap between the second image reading unit 7 and the document conveyance surface 24 is determined by the radius to the contact position between the rotation center of the rolling roller and the document conveyance surface 24. FIG. 8A shows a case where the rolling roller 33b is stationary on the document conveying surface 24 at a position where the radius from the rotation center is the minimum. In this case, the conveyance gap G is set to a minimum value suitable for image reading of a thin document such as a sheet document.

  FIG. 8B shows a position where the second image reading unit 7 is moved to the left in the drawing along the width direction by the driving means 26 and the rolling roller 33b is rotated about 90 °. The conveyance gap G3 at this position increases steplessly from the minimum conveyance gap G in FIG. 8A in accordance with the rotation amount of the rolling roller 33b, that is, the movement amount of the second image reading unit 7.

  FIG. 8C shows a position where the second image reading unit 7 is further moved leftward in the drawing along the width direction and rotated 180 ° from the position shown in FIG. At this position, the radius from the rotation center of the rolling roller 33b to the document conveying surface 24 is maximized, so that the conveyance gap G4 is maximized. The maximum conveyance gap G4 can be determined based on the thickness of the thickest document that can be conveyed by the image reading apparatus 1. Thus, in this embodiment, the conveyance gap can be adjusted steplessly from the minimum to the maximum.

  As mentioned above, although this invention was demonstrated in relation to the preferred embodiment, this invention is not limited to the said embodiment, In the technical scope, it can implement with a various change or deformation | transformation. Needless to say. For example, in the above embodiment, the conveyance path is set so that the sheet original and the card original pass through the gap between the first and second image reading units in the same direction, but the conveyance path of the sheet original and the card original is reversed. It can also be oriented.

DESCRIPTION OF SYMBOLS 1 ... Image reading apparatus 2 ... Lower unit 3 ... Upper unit 4 ... 1st platen glass 5 ... 1st image reading part 7 ... 2nd image reading part 10 ... Paper feed tray 11 ... ADF main body 12 ... Paper discharge tray 13 ... 1st 1 document transport path 20 ... second document transport path 24 ... document transport surfaces 25a, 25b, 29a, 29b ... projections 27a, 27b ... projections 32a, 32b, 28a, 28b ... contact surfaces 30 ... frame portions 31a, 31b ... concave portions 33a, 33b ... rolling roller 36 ... spring

Claims (9)

A document conveyance surface having a reading position along a document conveyance path through which the document is conveyed;
An image reading unit arranged to face the document conveyance surface for reading an image of the document conveyed along the document conveyance surface;
The image reading unit is movable in the width direction intersecting the document conveyance direction with respect to the document conveyance surface, and is at least one pair projecting from the image reading unit toward the document conveyance surface in the width direction. With protrusions of
The document conveying surface has a contact surface for receiving the pair of protrusions of the image reading unit;
Since the gap between the image reading unit and the document conveying surface is at least a first gap and a second gap having different lengths, the image reading unit is in the width direction with respect to the document conveying surface. An image reading apparatus in which at least one of a height of the abutting surface that abuts on the projecting portion and a projecting height of the projecting portion changes depending on the position of the projecting portion.   The image reading apparatus according to claim 1, further comprising means for urging the image reading unit toward the contact surface of the document conveying surface.   The image reading apparatus according to claim 1, wherein the contact surface is provided at a height different from the document conveyance surface and the document conveyance surface.   The image reading apparatus according to claim 3, wherein the contact surfaces are provided at the document conveyance surface and a plurality of heights that are stepwise different from the document conveyance surface.   4. The image reading apparatus according to claim 1, wherein the contact surface having a height different from that of the document conveying surface is provided on a protrusion of the document conveying surface. 5.   The image reading apparatus according to claim 1, wherein the contact surface having a height different from that of the document conveying surface is provided in a recessed portion of the document conveying surface.   The image reading apparatus according to claim 1, wherein a protruding height of the protruding portion of the image reading unit changes in accordance with a movement amount of the image reading unit in the width direction.   The image reading apparatus according to claim 7, wherein the protrusion of the image reading unit is an eccentric roller having a rotation center in the document conveyance direction.   The image reading apparatus according to claim 1, further comprising a driving unit that moves the image reading unit in the width direction, and the driving unit is driven and controlled in accordance with a thickness of the document.

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