JP2009044511A - Image sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensor in which a semiconductor chip constituting a sensor element can be small-sized and while maintaining miniaturization as a whole, a focal point depth is made deep. <P>SOLUTION: The image sensor forms an image in a read region L extending in a main scanning direction while being reduced and inverted on a sensor chip 600 via a lens 350. The sensor chip 600 includes a plurality of sensor chips 600 in each of which a predetermined number of photo-detectors are arrayed on its upper surfaces and read regions L1, L2... for image formation respectively within effective photo-detection ranges H1, H2... of neighboring sensor chips (601, 602) are overlapped with each other at their terminal portions for a predetermined length. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image sensor, and is an image configured to read a two-dimensional image by sequentially reading a line-like image extending in the main scanning direction while moving relative to the document in the sub-scanning direction. It relates to sensors.

  This conventional main image sensor is described in Patent Document 1, for example. This image sensor is of a so-called flat bed type, and moves in the sub-scanning direction below transparent glass whose upper surface is a document placement surface. The image sensor includes an illumination light source that illuminates an area extending in the main scanning direction on the document placement surface, a lens that forms reflected light from the document at an equal magnification, and an image formed by the lens. A sensor element for receiving light. In the sensor element, a plurality of light receiving elements are arranged in a row in the main scanning direction. Each time the image sensor moves a predetermined distance in the sub-scanning direction, the sensor element sequentially reads a line-shaped image in the main scanning direction on the document.

Japanese Patent Laid-Open No. 11-74497

  By the way, the above-described conventional image sensor reads a line-shaped image extending in the main scanning direction at an equal magnification, so that the sensor element has a series of lengths in the main scanning direction corresponding to the reading width. Specifically, a plurality of semiconductor chips each having a predetermined number of light receiving elements formed at equal intervals are arranged closely in the longitudinal direction.

  On the other hand, due to recent technological innovation, it is possible to increase the density of elements to be formed on the main surface of the semiconductor chip. However, in the case of the image sensor of Patent Document 1, the reading resolution is restricted on the semiconductor chip. In addition to forming a plurality of light receiving elements at a predetermined pitch, the semiconductor chip is generally increased in size and the material cost cannot be reduced.

  In general, a so-called SELFOC lens is used as the lens, but this lens has a shallow depth of focus, and if the document on the document placement surface is lifted, the read image of that part becomes blurred. There is also a problem of end.

  The present invention has been conceived under the circumstances described above. It is an object of the present invention to provide an image sensor having a deep focal depth while reducing the size of the semiconductor chip constituting the sensor element and maintaining the overall size reduction.

  In order to solve the above problems, the present invention employs the following technical means.

  That is, the image sensor according to the present invention is an image sensor that forms an image of a reading area extending in the main scanning direction on a sensor element through a lens, and the sensor element includes a predetermined number of light receiving elements. A plurality of sensor chips arranged on the upper surface are configured, and a reading area that is imaged in each effective light receiving area of two adjacent sensor chips is overlapped by a predetermined length between their end portions. It is characterized by being.

  On each sensor chip, an image of a reading area in charge of these is reduced and formed. Therefore, the sensor chips can be arranged apart from each other in the main scanning direction. Thereby, each sensor chip can be reduced in size, and the material cost can be reduced.

  Adjacent sensor chips are arranged such that the end portions of the reading areas in charge thereof overlap each other by a predetermined length. Therefore, in the reading of a series of images extending in the main scanning direction, it is possible to effectively avoid a situation in which a part of the image is missing.

  In a preferred embodiment, the image sensor holds, in a case, an illumination light source for illuminating the reading area, a substrate on which the plurality of sensor chips are mounted, and the lens corresponding to each sensor chip. Holding means.

  In a preferred embodiment, the illumination light source includes a light emitting element and a light guide member having an emission surface on which light emitted from the light emitting element is incident and which emits light toward the reading region. On the other hand, a reflection surface is formed on the outer surface of the light guide member, and an image of the reading area is formed on the sensor element via the reflection surface and the lens. Has been.

  According to such a configuration, a sufficient optical path length from the reading area to the sensor element can be obtained, and the focal depth of the lens can be set deep. As a result, even if the original in the reading area is lifted, it is possible to effectively avoid a situation in which the read image is blurred.

  A preferred embodiment also includes one or more additional reflecting surfaces that further reflect the light reflected by the reflecting surface and enter the lens.

  According to such a configuration, the optical path length from the reading area to the sensor element can be further extended, and the focal depth of the lens can be set deeper.

  In a preferred embodiment, the reading is performed by arranging an index in an overlapping portion of the reading areas corresponding to the two adjacent sensor chips, and among the plurality of light receiving elements included in one of the two sensor chips, The index is adjusted so as to exclude data from the light receiving elements on the end side of the sensor chip including the light receiving elements on which the image is formed.

  According to such a configuration, an image of a reading area extending in the main scanning direction can be acquired without being excessive or insufficient.

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the drawings.

  Hereinafter, a preferred embodiment of the present invention will be specifically described with reference to the drawings.

  1 to 4 show a first embodiment of an image sensor according to the present invention. As shown in FIG. 1, the image sensor 100 according to this embodiment is configured as a so-called flat bed type that moves below a transparent glass 200 whose upper surface is a document placement surface 200 </ b> A.

  The image sensor 100 includes a case 300 in which an illumination light source device 400, a plurality of lenses 350, and a plurality of sensor chips 600 mounted on a substrate 500 are incorporated.

  The case 300 has a longitudinal axis in the direction perpendicular to the plane of FIG. 1, and includes a bottom wall 301, a side wall 302 rising from one edge of the bottom wall 301 in the short direction, and both ends of the bottom wall 301 in the longitudinal direction. And an end wall 303 that rises from the edge. The other end of the case 300 in the short direction is open, and a long rectangular substrate 500 is attached thereto. The case 300 also has a partition wall 310 that holds a lens 350 to be described later and partitions the space in the case 300.

  An illumination light source device 400 is mounted on a portion of the upper surface of the partition wall 310 close to the substrate 500. The illumination light source device 400 includes a longitudinal light guide member 410 having a smooth surface made of a transparent resin such as PMMA and polycarbonate, and light emitting elements disposed at one end or both ends of the light guide member 410. The light guide member 410 has an emission surface 411 for emitting illumination light toward the reading region L extending in the main scanning direction (the direction orthogonal to the plane of FIG. 1) on the transparent glass 200. The light guide member 410 also includes a reflection portion 412 for reflecting light incident from the end portion thereof toward the emission surface 411. This reflection part 412 is formed by forming the recessed part 412a or the convex part 412b intermittently so that it may appear well in FIG. As the light emitting element 450, a package type LED device 450a or the like is preferably used and mounted on an appropriate substrate 451. Power supply to the LED device 450a can be performed through the substrate 500. As shown in FIG. 2, the light from the light emitting element 450 incident from the end portion of the light guide member 410 travels in the longitudinal direction while being totally reflected by the side surface of the light guide member 410, but is reflected by the reflection portion 412. Then, the light reaching the emission surface 411 at an angle smaller than the total reflection critical angle is emitted from the emission surface 411 as illumination light.

  In this embodiment, the light guide member 410 is inclined at 45 ° with respect to the transparent glass 200, and light incident from the transparent glass 200 downward in the vertical direction is changed by 90 °. A reflective surface 460 for directing in the direction is integrally formed. The reflective surface 460 can be formed by depositing a metal film on a flat surface formed at an appropriate portion of the light guide member 410. The significance of the reflecting surface 460 will be described later.

  A prism 470 is provided adjacent to the side wall 302 of the case 300. The prism 470 is for changing the traveling direction of the light traveling from the reflecting surface 460 in the short direction of the case as described above by 180 ° between the two reflecting surfaces 471 and 472. That is, the prism 470 includes a vertical entrance / exit surface 470a and two reflecting surfaces 471, 472 inclined at an angle of 45 ° in opposite directions with respect to the entrance / exit surface 470a. It is made of resin or the like. Of course, two mirrors corresponding to the two reflecting surfaces 471 and 472 may be arranged in place of the prism 470.

  As shown in FIGS. 1 and 3, a plurality of convex lenses 350 arranged at predetermined intervals in the longitudinal direction of the case are held between the prism 470 and the substrate 500. As described above, the case 300 is provided with the partition wall 310, and the partition wall 310 has the horizontal portion 311 and the vertical portion 312, and the lens holding hole provided in the vertical portion 312. The convex lens 350 is held at 313.

A plurality of sensor chips 600 are mounted on the substrate 500. The sensor chip 600, as shown in FIG. 4, a semiconductor chip that is integrally formed with a plurality of light receiving elements d ₁ to d _n on the upper surface, so as to correspond to each optical axis of the convex lens 350, a main They are arranged at predetermined intervals on a straight line extending in the scanning direction. The substrate 500 is also mounted with a control device (not shown) that controls reading of image data from the sensor chip 600.

  As can be understood from the above, the image sensor 100 is configured to display images extending in the main scanning direction of the document D placed on the document placement surface 200A on the upper surface of the transparent glass 200 and illuminated by the illumination light source device 400. The image is read by forming a reduced inverted image on each sensor chip 600 corresponding to each convex lens 350 by the convex lens 350. That is, the reflected light from the document D is incident on the convex lens 350 via the reflecting surface 460 and the two reflecting surfaces 471 and 472 of the prism 470 formed integrally with the light guide member 410, and is imaged on the sensor chip 600. The Specifications such as the optical path length from the document D to the convex lens 350, the optical path length from the convex lens 350 to the sensor chip 600, the focal length of the convex lens 350, etc. are obtained by using a sensor chip with a predetermined reduction magnification of an image of a reading area of a predetermined length on the document. It is set so that an image is formed in an effective light receiving range on 600.

  However, in the present invention, the arrangement positions of the sensor chips 600 in the main scanning direction are particularly set as follows. That is, as shown in FIG. 3 schematically showing the optical path from the reading area L on the document placement surface 200A to each sensor chip 600, the effective light receiving ranges H1, H2,... Of adjacent sensor chips 601, 602. The reading areas L1, L2,... On the document placement surface 200A that are imaged are overlapped by a predetermined length. This overlapping range is, for example, a predetermined number of pixels.

The image sensor 100 having the above configuration is, for example, initialized as follows before shipment. That is, a line-shaped index M extending in the sub-scanning direction is arranged at an overlapping portion of each reading area L1, L2,..., And reading is performed using all effective light receiving ranges of each sensor chip 600 in that state. Then, the same index M is read at the ends of the effective light receiving ranges H1 and H2 of the adjacent sensor chips 601 and 602. In FIG. 4, the hatched light receiving element d ₄ on the sensor chip 601 and the hatched light receiving element dn _-3 on the sensor chip 602 receive the same index M image. Show. Then, for any one of the adjacent sensor chips (601 or 602), including the light receiving element (d ₄ or d _n-3 ) from which the index M has been read, the end of the sensor chip 600 is further The light receiving elements are specified, and the data from these light receiving elements are excluded from the series of image data. For example, in FIG. 4, the data from the light receiving element d ₁ to d ₄ of the sensor chip 601, or exclude data from the light receiving element d _n-3 ~d _n of the sensor chip 602 from the series of image data. By doing so, even if there is an overlapping portion in the reading regions L1, L2,... Corresponding to the adjacent sensor chips 601, 602, the image of the same portion is prevented from being read twice. Information on the light receiving elements specified to exclude data as described above is recorded in a memory provided in a control device (not shown).

  Next, the operation of the image sensor 100 having the above configuration will be described.

A document D to be read is placed on the document placement surface 200 </ b> A on the upper surface of the transparent glass 200. The image sensor 100 sequentially reads images in the reading region L in the main scanning direction on the document D while moving in the sub-scanning direction. That is, for each of the reading areas L1, L2,... That each sensor chip 600 is in charge of, the image is reduced and inverted on each sensor chip 600, and from each sensor chip 600, the light receiving elements d _{1 to} d are sequentially formed. Data for every _n is output serially as image data. However, since the image formed on each sensor chip 600 is an inverted image, the control device connects the serial data from each sensor chip 600 to the outside while reversing the order. At this time, as described above, the data on the light receiving elements specified to be excluded from the adjacent sensor chips 601 and 602 are automatically excluded. By performing such a reading operation every time the image sensor 100 is moved a predetermined distance in the sub-scanning direction, two-dimensional image data of the document can be acquired.

  In the image sensor 100 having the above-described configuration, by using the reflective surfaces 460 and 472 provided on the light guide member 410 and the prism 470, the optical path length from the document D to the convex lens 350 can be obtained. The depth of focus of the convex lens 350 can be increased. For this reason, even if the document D is slightly lifted, the problem that the read image of that portion is blurred is reduced, and the quality of the read image can be improved.

  Further, since the images of the read areas L1, L2,... That are in charge are reduced and formed on each sensor chip 600, the sensor chip 600 can be reduced in size, and the material cost can be reduced.

  Further, since the ends of the reading areas L1, L2,... That the adjacent sensor chips 600 (601, 602) are in charge of each other overlap, there is some error in the mounting position of the sensor chip 600 with respect to the substrate in the main scanning direction. Even if it occurs, it is possible to prevent the image from being lost in the read data.

  In addition, since a part of the reflection surface 460 provided to increase the optical path length from the document D to the convex lens 350 is formed using the outer surface of the light guide member 410 of the illumination light source device 400, a separate mirror or the like is formed. The number of parts can be reduced compared to the provision of the reflective surface.

  FIG. 5 shows a second embodiment of the image sensor according to the present invention in a cross section of the main part. This image sensor 100A extends the optical path length from the document D to the convex lens 350 further than the image sensor 100 according to the first embodiment. That is, the prism 470 in the image sensor 100 </ b> A has a first refracting surface 471 to a sixth reflecting surface 476, and the light traveling in the short direction of the case 300 from the reflecting surface 460 of the light guide member 410 travels in a folded manner. It is changed so that it enters the convex lens 350. The rest of the configuration is the same as that of the first embodiment shown in FIGS.

  According to such a configuration, the depth of focus of the convex lens 350 can be increased to prevent the image quality from being deteriorated due to the rising of the document D, and the reduction magnification of the image formed on the sensor chip 600 can be further increased. The sensor chip 600 can be further downsized.

  FIG. 6 shows a third embodiment of the image sensor according to the present invention in a cross-sectional view. In this image sensor 100B, two prisms 470A, 470B having a plurality of reflecting surfaces 471, 472,... Are arranged at both ends of the case 300 in the short direction, and reflected light from the document D is transmitted to the short side of the case 300. The direction is changed into a spelling shape by making the best use of the width dimension in the direction and is incident on the convex lens 350. Further, the reflecting surface for changing the direction of light from the reading region L by 90 ° is assigned to the reflecting surface 471 of one prism 470A. Further, the illumination light source device 400 is mounted on the outer surface side of the substrate 500. The rest of the configuration is the same as that of the first embodiment shown in FIGS.

  According to such a configuration, while the optical path length from the document D to the convex lens 350 can be gained, the size of the case 300 in the short direction can be saved, and the image sensor 100B itself can be downsized. be able to.

  Of course, the scope of the present invention is not limited to the above-described embodiments, and all modifications within the scope of matters described in the claims are all included in the scope of the present invention.

  For example, although the embodiment is configured as a so-called flat bed type, a transparent glass is installed on the upper surface of the case, and a so-called flat plate is pressed against the surface of the transparent glass by a platen and conveyed in the sub-scanning direction. Of course, it can be configured as a contact image sensor.

It is sectional drawing of one Embodiment of the image sensor which concerns on this invention. It is an expanded sectional view which follows the II-II line of FIG. FIG. 2 is a schematic diagram showing a developed optical path from a reading area to a sensor chip in the image sensor of FIG. 1. It is explanatory drawing of an effect | action of the image sensor of FIG. It is sectional drawing of other embodiment of the image sensor which concerns on this invention. It is sectional drawing of other embodiment of the image sensor which concerns on this invention.

Explanation of symbols

100, 100A, 100B Image sensor 200 Transparent glass 200A Document placement surface 300 Case 301 Bottom wall 302 Side wall 303 End wall 310 Partition wall 311 Horizontal portion 312 Vertical portion 350 Lens 400 Illumination light source device 410 Light guide member 411 Emitting surface 450 Light emission Element 460 Reflective surface 470 Prism 471,472 Reflective surface 500 Substrate 600 Sensor chip D Document H1, H2 Effective light receiving range of sensor element L Reading area L1, L2 Reading area received by each sensor element d _{1 to} d _n Light receiving element

Claims (5)

An image sensor for forming an image of a reading region extending in the main scanning direction on a sensor element through a lens in a reduced inverted manner,
The sensor element includes a plurality of sensor chips in which a predetermined number of light receiving elements are arranged on the upper surface.
An image sensor, characterized in that a reading area formed on each effective light receiving range of two adjacent sensor chips is overlapped by a predetermined length between their end portions.   An illumination light source for illuminating the reading area, a substrate on which the plurality of sensor chips are mounted, and a holding unit that holds the lens corresponding to each sensor chip are provided in the case. The image sensor according to 1. The illumination light source is configured to include a light emitting element and a light guide member having an emission surface on which light emitted from the light emitting element is incident and which emits light toward the reading region.
A reflection surface is formed on an outer surface of the light guide member, and an image of the reading area is formed on the sensor element via the reflection surface and the lens. Item 3. The image sensor according to Item 2.   The image sensor according to claim 3, further comprising one or a plurality of additional reflection surfaces that further reflect the light reflected by the reflection surface and enter the lens.   Light reception in which an index is arranged at an overlapping portion of the reading areas corresponding to the two adjacent sensor chips and reading is performed, and among the plurality of light receiving elements included in one of the two sensor chips, the index is formed. 5. The image sensor according to claim 1, wherein the image sensor is adjusted so as to exclude data from the light receiving element on the end side of the sensor chip including the element.

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