JP2010118989A - Image reader - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image reader capable of coping with reading of placed originals and reading of conveying originals without increasing LED elements of light sources. <P>SOLUTION: The light source 33 is composed by linearly arranging a number of LED elements 42, and is set in a width direction of a flat bed platen 32. When a carriage 35 to which the light source 33 is mounted moves toward platen glass 30 to read conveying originals, the carriage 35 moves along a guide rail 43, and is set while being positionally misaligned by a prescribed length in the direction of read lines by an inclined groove formed at an end 46 of the guide rail 43, thus positioning the light source corresponding to the misalignment of the reference positions of the originals in the placement and conveyance of the originals. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image reading apparatus applicable to an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

  When reading an image of a document, in a state where the document is placed, the reading unit sequentially reads along the reading line while supporting the reading unit on the carriage and moving the carriage in the scanning direction, and reads it as two-dimensional image data. Things have been done. In addition, a document is transported across the reading line while the reading unit is stationary, and a reading operation is sequentially performed to read as two-dimensional image data. An image reading apparatus has been developed in which a single reading unit can perform both a reading operation by conveying a document and a reading operation in a document placement state.

When performing these two different reading operations, various improvements have been proposed in order to increase the image reading accuracy. For example, in Patent Document 1, when the height of the original surface is different between the original fixed reading and the original flow reading, the height of the rail that guides the shared reading unit that reads the original image is changed at each reading position. An image reading apparatus set to be performed is described. Further, Patent Document 2 describes an image reading apparatus in which an LED array is turned on and displayed in accordance with a set reading area.
JP 2005-277774 A JP 2001-183760 A

  5 and 6 are schematic front views of the internal structure of the conventional image reading apparatus 1. FIG. 5 shows a reading operation state when the document is conveyed, and FIG. 6 shows a reading operation state when the document is placed. Show. The image reading apparatus 1 is provided with a document conveying section 2 on the upper surface of the image reading section 3, and the document conveying section 2 is a cover that can be opened and closed.

  At the time of document conveyance reading, as shown in FIG. 5, the document is loaded on the document tray 10, and the conveyance path indicated by the dotted thick line arrow M by the pickup roller 12, the feed roller 13, the registration roller 14 and the discharge roller 15. It is discharged to 11 through the discharge tray. A strip-shaped platen glass 16 is disposed on the downstream side of the registration roller 14 so as to cross the conveyed document. The carriage 17 of the image reading unit 2 is positioned at a stationary reading position facing the platen glass 16, and the reading line of the reading unit (such as an optical reading sensor) of the carriage 17 is set within the range of the platen glass 16 and conveyed. Read the original.

  At the time of document placement reading, as shown in FIG. 6, the document conveying section 2 is opened and a document is placed on the upper surface of the platen bed 18 as indicated by a dotted line N. The platen bed 18 is made of a rectangular transparent glass, and the entire document is placed on the platen bed 18. While sequentially moving the carriage 17 from the reading start position in the sub-scanning direction X, the reading unit of the carriage 17 reads the document placed through the platen bed 18 along the reading line.

  In the conventional image reading apparatus described above, the reading line is set in a direction orthogonal to the sub-scanning direction of the carriage that supports the reading unit. A light source for irradiating a document area along the reading line is mounted on the carriage.

  As such a light source, an illumination device such as a xenon or a cold cathode tube is used. Recently, a light source in which a large number of LED elements are arranged along a reading line has been used. By using the LED element, there is an advantage that it is possible to reduce the size, the weight, and the cost.

  When LED elements are arranged in a line and used as a light source, it is necessary to set the line length in accordance with the size of the document to be read. FIG. 7 is an explanatory diagram of line lengths required for document placement reading and document conveyance reading. At the time of document placement reading, since the document is placed with reference to the corner position at the back of the platen bed 18 (the position of the triangular mark indicated by the symbol A), for example, when the document size is set up to A3 size, A3 The length of the line for irradiating the medium width (length d1) is required. On the other hand, at the time of document conveyance reading, the document is loaded on the document tray 10 with reference to the center position of the platen glass 16 (the position of the triangular mark indicated by symbol B). For this reason, the position of the line for irradiating the width (length d1) of the A3-size document is set to a position shifted by the length d2 from the time of document placement reading.

  Therefore, when both reading operations are performed by one reading unit, the length of the light source for arranging the LED elements must be set so as to irradiate a length (d1 + d2) larger than the A3 size width (d1). Instead, it is necessary to arrange the LED elements by an extra length (d2). Moreover, the power consumption for irradiating only the part for which the LED element increased will increase.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading apparatus that can cope with document placement reading and document conveyance reading without increasing the number of LED elements of a light source.

  An image reading apparatus according to the present invention includes at least a carriage that supports the light source and a moving unit that moves the carriage in an image reading apparatus that reads a document along a reading line by irradiating with a light source in which a plurality of LED elements are arranged. A positioning unit that positions the carriage at a stationary reading position at the time of document conveyance reading, and a controller that controls the moving unit to scan the carriage at the time of document placement reading, and positions the carriage at the stationary reading position. In this case, there is provided a setting unit for positioning the carriage by moving it by a predetermined length in the direction of the reading line. Further, the setting unit moves the carriage by a difference between a document setting reference position at the time of document placement reading and a document setting reference position at the time of document conveyance reading.

  With the above configuration, the carriage is moved by a predetermined length in the direction of the reading line when positioning to the stationary reading position, so that the reference of the document at the time of document placement reading and document conveyance reading Even when the position is shifted, it is possible to cope without increasing the number of LED elements. Therefore, since only the LED elements necessary for irradiation of the reading line need be arranged, no extra LED elements are required, and power consumption necessary for irradiation can be reduced.

  Hereinafter, embodiments according to the present invention will be described in detail. The embodiments described below are preferable specific examples for carrying out the present invention, and thus various technical limitations are made. However, the present invention is particularly limited in the following description. Unless otherwise specified, the present invention is not limited to these forms.

  FIG. 1 is a schematic sectional view of an embodiment according to the present invention. The document reading device 1 includes a document conveying unit 2 and a document reading unit 3, and is carried by the document conveying unit 2 set on the document tray 10 and conveyed to the document reading unit 3. Then, the document read by the document reading unit 3 is discharged to the discharge tray 11.

  The document transport unit 2 is provided with a pickup roller 21 and a separation roller 22, and the document placed on the document tray 10 is drawn by the pickup roller 21, and the leading edge of the document is sandwiched by the separation roller 22. The separation roller 22 carries documents one by one, and the leading edge of the loaded document is sandwiched between the feed roller 23 and the press roller 24 and conveyed.

  The document is further conveyed downward along the outer periphery of the feed roller 23 and is sandwiched between the press roller 24 and the feed roller 23. The sandwiched document is conveyed to the reading position along the document guide member 25 disposed close to the lower portion of the feed roller 23.

  The document reading unit 3 is provided with a platen glass 30 facing the feed roller 23. The document transported by the document transport unit 2 passes between the document guide member 25 and the platen glass 30, is guided upward by the guide protrusion 31, and is sandwiched between the discharge roller 26 and the press roller 27. Become. Then, the paper is discharged to the discharge tray 11 by the discharge roller 26.

  The document transport unit 2 also serves as a document cover. When reading a book or the like, the document transport unit 2 is rotated upward to place a portion to be read such as a book on the flat bed platen 32.

  Inside the document reading unit 3, a carriage 35 on which a light source 33 and a reflection mirror 34 are mounted is provided so as to freely move in a sub-scanning direction along a guide rail (not shown). Similarly, the carriage 38 on which the reflection mirrors 36 and 37 are mounted is provided so as to freely move in the sub-scanning direction along the guide rail.

  The carriages 35 and 38 are connected to the moving mechanism 39 via a belt. The carriages 35 and 38 are transported to a belt by a drive motor of the moving mechanism 39 being rotated and reciprocated along the lower surface of the flat bed platen 32. Then, while the carriage 35 moves according to the size of the document placed on the flat bed platen 32, the document is irradiated by the light source 33, the reflected light is reflected by the reflection mirror 34, and transmitted to the reflection mirror 36.

  The carriage 38 moves by a half distance in synchronization with the movement of the carriage 35. Then, the reflected light from the original transmitted from the reflection mirror 34 is reflected by the reflection mirror 36, transmitted to the reflection mirror 37, and further reflected by the reflection mirror 37.

  An optical reading element 41 including a condenser lens 40 and a CCD is provided inside the document reading unit 3, and reflected light from the document reflected by the reflection mirror 37 is collected by the condenser lens 40. Thus, the optical reading element 41 is set to form an image. The reflected light from the document input to the optical reading element 41 is converted into an electric signal and transmitted to an image processing circuit (not shown).

  When the carriages 35 and 38 are moved, the distance between the reflecting mirror 34 and the reflecting mirror 36 changes, but the optical axes of the two always move so as to coincide with each other, and the reflected light from the original is always transmitted accurately. It has become so.

  When reading a document conveyed by the document conveying unit 2, the carriages 35 and 38 are moved to a stationary reading position facing the platen glass 30 (indicated by dotted lines), and a reading operation is performed in a stationary state. In this case, the original to be conveyed is irradiated by the light source 33 and the reflected light is transmitted to the optical reading element 41 by the reflection mirrors 34, 36 and 37.

  FIG. 2 is a schematic view of the platen glass 30 and the flat bed platen 32 as viewed from above. The light source 33 is configured by arranging a large number of LED elements 42 in a line, and the arrangement direction is set to the width direction of the flat bed platen 32 that is orthogonal to the sub-scanning direction that is the carriage movement direction. Has been. A reading line is set in the width direction of the flat bed platen 32 with respect to the document placed on the flat bed platen 32, and light emitted from the LED element 42 of the light source 33 is irradiated to the document along the reading line. Will be reflected.

  Both ends of the carriages 35 and 38 are slidably supported by grooves of a pair of guide rails 43 provided on both sides. And it is made to reciprocate along the guide rail 43 by the moving mechanism 39 mentioned above.

  The end portions 44 on both sides of the carriage 35 are disposed so as to overlap the upper portion of the guide rail 43, and the engaging protrusions 45 projecting from the lower surface of the end portion 44 are fitted in the groove portions of the guide rail 43. The carriage 35 can smoothly move along the guide rail 43 by sliding the engagement protrusion 45 inside. Similarly, the carriage 38 is also provided with engagement projections at both ends, and the engagement projections are fitted into the groove portions and moved along the guide rail.

  At the end 46 on the platen glass 30 side of the guide rail 43, a groove is formed so as to be inclined by a predetermined length in the reading line direction.

  3 and 4 are explanatory diagrams showing a state when the carriages 35 and 38 are moved to the stationary reading position. In FIG. 3, the carriage 38 moves along the guide rail 43 and reaches its end 46. For this reason, it is set at a position shifted by a predetermined length in the direction of the reading line from the position moving along the guide rail 43. The carriage 35 is not displaced in the reading line direction (main scanning direction) because it is before moving along the guide rail 43 and reaching the end 46.

  In FIG. 4, the carriage 35 moves to the end 46 and the engaging protrusion 45 enters the inclined groove, and the carriage 35 is set at a position shifted by a predetermined length in the reading line direction. In this setting state, the carriages 35 and 38 are positioned at the stationary reading position, and the document conveyance reading operation is performed.

  The positional deviation amount of the carriage in the reading line direction includes the document placement reference position at the time of document placement reading (position of the back corner of the flat bed platen 32) and the document placement reference position at the time of document conveyance reading (center of the platen glass 30). The position is set to have the same length.

  For this reason, if the LED elements of the light source 33 are arranged corresponding to the reading line at the time of document placement reading, the carriage is displaced corresponding to the reading line at the time of document conveyance reading. Therefore, the light source 33 can be used as it is. it can. Therefore, it is not necessary to arrange extra LED elements of the light source 33, and power consumption can be reduced by that amount.

  In the example described above, the groove portion of the guide rail is formed to be inclined so that the carriage is displaced by a predetermined length in the reading line direction. However, if the carriage can be displaced in the reading line direction, Other methods may be used. Further, if the light source itself is set to be displaced by a predetermined length, a conventional carriage moving mechanism can be used as it is.

It is a schematic sectional drawing regarding embodiment which concerns on this invention. It is the schematic diagram seen from the upper direction of platen glass and a flat bed platen. It is explanatory drawing which shows the state at the time of a carriage moving to a stationary reading position. It is explanatory drawing which shows the state at the time of a carriage moving to a stationary reading position. It is a schematic front view regarding the reading operation state at the time of document conveyance of the conventional image reading apparatus. It is a schematic front view regarding the reading operation state at the time of document placement of the conventional image reading apparatus. FIG. 5 is an explanatory diagram of line lengths required for document placement reading and document conveyance reading.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Original reading apparatus 2 Original conveyance part 3 Original reading part
23 Feed roller
25 Document guide member
30 platen glass
32 flatbed platen
33 Light source
34 Reflection mirror
35 Carriage
36 Reflective mirror
37 Reflection mirror
38 Carriage
39 Movement mechanism
40 condenser lens
41 Optical reader
42 LED elements
43 Guide rail

Claims (2)

  In an image reading apparatus that reads a document along a reading line by irradiating with a light source in which a plurality of LED elements are arranged, at least a carriage that supports the light source, a moving unit that moves the carriage, and the carriage during document conveyance reading And a control unit for controlling the moving unit to scan the carriage at the time of document placement reading, and the carriage at the position of the reading line when positioning the carriage at the stationary reading position. An image reading apparatus comprising a setting unit that moves and positions in a direction by a predetermined length.   The image reading apparatus according to claim 1, wherein the setting unit moves the carriage by a difference between a document setting reference position at the time of document placement reading and a document setting reference position at the time of document conveyance reading.

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