JP2007235942A - Image sensor module and image reader using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensor module capable of shortening read time from approximately 10 seconds to approximately 1 second sharply, and to provide an image reader using the image sensor module. <P>SOLUTION: The image sensor module A1 comprises: a substrate 1; a light emission means 4 that is mounted onto the substrate 1 and emits light to an original Dc; a photoelectric conversion means that is mounted onto the substrate 1 and receives light reflected by the original Dc; and an optical system that is mounted onto the substrate 1 and forms the image of the original Dc on the photoelectric conversion means. The photoelectric conversion means is an image pickup device 2 having a plurality of light reception elements arranged in a matrix shape. The optical system has a group of lenses including a lens that becomes aspherical, where the closer an incidence surface advances toward the peripheral part, the larger the curvature becomes. As a result, a lens unit 3 can form an image of which an angle is wide and distortion is small. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image sensor module and an image reading apparatus using the same.

  In order to read the contents described in a document or the like as image data, an image reading apparatus equipped with an image sensor module is generally used. FIG. 6 shows a conventional image sensor module X and an image reading apparatus Y using the same. The image reading apparatus Y shown in the figure is an apparatus that reads the content described on the original Dc, which is a reading object, by a transmission method. An image sensor module X and a control IC 93 are accommodated in the case 96 of the image reading apparatus Y. The image sensor module X can scan the inside of the case 96 in the left-right direction in the figure by driving means (not shown), and includes an optical unit 91 and an image sensor 92. The optical unit 91 includes a plurality of mirrors and a plurality of rod lenses arranged in the depth direction of the drawing, and reflects the light coming from the upper side of the image sensor unit X in the drawing, and then the image sensor 92. It is for imaging on top. The image pickup element 92 includes a light receiving unit composed of a plurality of light receiving elements arranged in the depth direction of the figure, and is configured to exhibit a photoelectric conversion function that outputs an electrical signal corresponding to the light received by the light receiving unit. It is said that. With such a configuration, the image sensor module X can simultaneously receive light extending in the depth direction of the drawing. The image sensor module X is connected to the control IC 93 via a flexible cable 94.

  A document Dc is set on the upper surface of the case 96 in the drawing. A transmissive light source 95 is disposed above the document Dc. When light is emitted from the transmissive light source 95, the light passes through the document Dc and travels downward in the figure. When the light passes through the document Dc, the saturation and lightness of the light are changed depending on the content of the document Dc. When the image sensor module X is scanned in the left-right direction in the drawing, the image sensor X continuously receives a part of the light transmitted through the document Dc as linear light. When the image sensor module X is scanned from one end to the other end of the document Dc, the control IC 93 restores image data from the output signal of the image sensor module X. As described above, the description content of the document Dc can be read as image data.

  However, since the image sensor module X is configured to receive linear light, it is necessary to scan the image sensor module X in the image reading apparatus Y in order to read a document Dc having two-dimensional description. is there. For this reason, reading the document Dc requires at least time for the image sensor module X to scan from one end of the document Dc to the other end. Therefore, it is difficult for the image reading apparatus Y to improve the reading speed. For the scanning of the image sensor module X, for example, a servo motor, a ball screw, or the like is used as the driving means described above. Since such a driving means is accommodated, the case 96 becomes bulky.

JP 2003-125176 A

  The present invention has been conceived under the circumstances described above, and it is an object of the present invention to provide an image sensor module and an image reading apparatus using the image sensor module capable of greatly reducing the reading time. To do.

    The image sensor module provided by the first aspect of the present invention is mounted on a substrate, the substrate, a light emitting means for emitting light to a reading object, and mounted on the substrate. An image sensor module comprising: photoelectric conversion means that receives the light reflected by the reading object; and an optical system that is mounted on the substrate and forms an image of the reading object on the photoelectric conversion means. The photoelectric conversion means is an image pickup device including a plurality of light receiving elements arranged in a matrix, and the optical system is an aspheric surface whose curvature increases as the incident surface moves from the center to the periphery. It is a lens unit configured to be capable of forming an image with a wide angle and a small distortion by including a lens group including a lens.

  According to such a structure, it is possible to image the said reading target object collectively with the said image pick-up element. For this reason, there is no need to relatively scan the reading object and the image sensor module. Therefore, the time for reading the object to be read can be significantly reduced from 1 second or less to 10 seconds or less.

  In a preferred embodiment of the present invention, the substrate has an elongated rectangular shape, the imaging element and the lens unit are disposed near the center of the substrate, and the light emitting means is provided at both ends of the substrate. It is composed of a pair of light sources arranged close to each other. According to such a configuration, it is possible to illuminate the periphery of the end of the reading object with a relatively high illuminance. This is suitable for avoiding the periphery of the edge of the image from becoming darker than the center portion in accordance with the cos 4 law of the angle of view during imaging.

  In a preferred embodiment of the present invention, each of the light sources includes a plurality of LED elements. According to such a configuration, it is possible to configure a light-emitting unit that saves power and has high luminance. In addition, since the LED element is relatively small in size, it is suitable for being arranged at a portion near both ends of the substrate.

  In a preferred embodiment of the present invention, the lens unit includes the lens group having an angle of view of 150 ° or more, and the distortion is ± 2% or less. According to such a configuration, it is possible to read the contents described in a wide area such as an A4 size document as clear image data. Further, it is advantageous for reducing the thickness of an image reading apparatus using the image sensor module.

  In a preferred embodiment of the present invention, the lens group includes a diverging lens group composed of a plurality of diverging lenses, and the diverging lens is a concave lens, and an incident surface of each concave lens surrounds the center. The aspherical surface has a curvature that increases toward the part, and the exit side is substantially a concave spherical surface. According to such a configuration, the lens unit is suitable for a configuration having a wide angle and a small distortion.

  In a preferred embodiment of the present invention, the diverging lens group includes three diverging lenses. Such a configuration is suitable for widening the angle and eliminating distortion of the lens unit.

  The image reading apparatus provided by the second aspect of the present invention includes the image sensor module provided by the first aspect of the present invention. According to such a configuration, there is no need to provide a mechanism for relatively scanning the image sensor module and the reading object. Therefore, the reading time can be greatly shortened, and the image reading apparatus can be reduced in size and cost.

  In a preferred embodiment of the present invention, a reflecting member or a prism is provided at a position farther from the light emitting means than the lens unit. According to such a configuration, it is possible to irradiate the entire reading object with light from the light emitting means.

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

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

  1 and 2 show a first embodiment of an image sensor module and an image reading apparatus using the same according to the present invention. The image reading apparatus B1 shown in the figure includes an image sensor module A1, a case 60, a cover 61, a transparent plate 62, and a reflecting member 63. The image reading device B1 is for reading the description content of the document Dc, which is a reading object, as image data.

  The image sensor module A1 includes a substrate 1, an image sensor 2, a lens unit 3, light emitting means 4, a control IC 51, and a memory chip 52. The image sensor module A1 has a function of restoring the description content of the document Dc as image data by receiving light reflected by the document Dc in the image reading device B1.

  The substrate 1 is, for example, a printed wiring board, and has a long rectangular shape as shown in FIG. The substrate 1 has a structure in which a metal wiring layer made of copper or the like and a resin layer are laminated. An image sensor 2 and a lens unit 3 are mounted on the center portion of the substrate 1. Light emitting means 4 are mounted on portions near both ends of the substrate 1. A control IC 51 and a memory chip 52 are mounted on a portion of the substrate 1 between the lens unit 3 and the light emitting means 4 disposed on the right side in the drawing.

  The image sensor 2 is called a CCD type or a CMOS type, for example, and has a light receiving unit 20. As shown in FIG. 3, the light receiving unit 20 has a rectangular shape and includes a plurality of light receiving elements 20a. The plurality of light receiving elements 20a are arranged in a matrix. In the present embodiment, the light receiving unit 20 is configured by 7,016 × 5,102 light receiving elements 20a, and has a size of about 14 mm × about 10 mm. Thus, the image sensor 2 can read the A4 size document Dc with a resolution of 600 DPI. Each light receiving element 20a has a size of 2 μm square. When the light receiving unit 20 receives light, an image signal having an output level corresponding to the amount of light received for each light receiving element 20a is output from the imaging device 2.

  The lens unit 3 is for forming the description content of the document Dc on the light receiving unit 20 of the image sensor 2 by transmitting and refracting the light traveling from the document Dc. As shown in FIG. 30, a lens group 31, and a filter 32. The holder 30 is fixed to the substrate 1, and is made of black or a dark synthetic resin having light shielding properties. The holder 30 is for holding the lens group 31 and the filter 32.

  The lens group 31 includes a plurality of lenses 31A, 31B, 31C, 31D, 31E, 31F, and 31G, and is configured to be capable of forming an image with a wide angle and small distortion. The plurality of lenses 31A, 31B, and 31C are disposed on the document Dc side, and are all concave lenses. The plurality of lenses 31 </ b> A, 31 </ b> B, and 31 </ b> C are so-called divergent lenses that exhibit the effect of spreading parallel light. The entrance surfaces 31Aa, 31Ba, and 31Ca of the plurality of lenses 31A, 31B, and 31C are aspheric surfaces whose curvature increases from the center toward the periphery, and the exit surfaces 31Ab, 31Bb, and 31Cb are concave spherical surfaces. Yes. It is most desirable that the concave spherical surface be an accurate spherical surface, but it may be slightly deviated from the spherical surface for achromatic or aberration correction. Good.

  The plurality of lenses 31D, 31E, 31F, and 31G are so-called converging lenses that focus incident light on a focal point. The lens 31D is a biconvex lens in which both the document Dc side and the image sensor 2 side are convex surfaces. The lens 31E is a lens having a convex surface on the document Dc side and a flat surface on the imaging element 2 side. The lenses 31F and 31G have aspheric surfaces 31Fa, 31Fb, 31Ga, and 31Gb. The aspheric surfaces 31Fa and 31Ga are both convex surfaces, and the aspheric surfaces 31Fb and 31Gb are both concave surfaces. The lens unit 3 is configured such that light from portions arranged at equal intervals on the document Dc can be imaged on the light receiving unit 20 at equal intervals. In the present embodiment, the angle of view of the lens unit 3 is about 160 to 170 °. Table 1 shows specifications of the plurality of lenses 31A, 31B, 31C, 31D, 31E, 31F, and 31G.

  Here, the diverging lenses of the lenses 31A, 31B, and 31C are lenses that expand the angle of view and greatly reduce the light rays from the original. In order to reduce the color blur of the acquired image as much as possible, the Abbe number is small. The largest possible material is desirable. The Abbe number 71.2 of these lenses 31A, 31B, and 31C in Table 1 can be realized by a molded lens made of low dispersion glass. On the other hand, the lenses 31E, 31F, and 31G can employ a combination that can form an image with little distortion by itself. The lens 31D plays a role of converging a light beam narrowed down from a large angle of view while being diverged by the diverging lens group and making it incident on the lenses 31E, 31F, and 31G for image formation. , 31B, 31C, it is desirable to use a lens made of a material having a low Abbe number in order to correct the color blur of the image caused by the diverging lenses 31A, 31B, 31C. The Abbe number of the lens 31D in Table 1 can be realized by a lens made of a resin material such as a volatilate. By using such a lens group, the distortion of the lens unit 3 is about -0.71%. The lens unit used in the image sensor module according to the present invention preferably has an angle of view of 150 ° or more and a distortion of ± 2% or less.

The filter 32 is for blocking light of a predetermined wavelength, and is an infrared blocking filter, for example. The filter 32 has a role of protecting the image sensor 2.

  The light emitting means 4 is for irradiating light toward the document Dc, and is composed of a pair of LED elements 41B, 41G, and 41R as shown in FIGS. The pair of LED elements 41B, 41G, and 41R are arranged separately near both ends of the substrate 1. The LED elements 41B, 41G, and 41R can emit blue light, green light, and red light, respectively.

  The control IC 51 is a semiconductor chip in which an arithmetic processing circuit is built. The control IC 51 controls the driving of the image sensor 2 and the light emitting means 4 mounted on the substrate 1, transfers data to the memory chip 52, and the image sensor module A 1 or image reading. Data transmission / reception with the outside of the device B1 is performed. The control IC 51 is provided with an A / D conversion unit. The A / D converter converts the image signal output from the image sensor 2 from an analog signal to a digital signal. The image data digitized by the A / D converter is output to the memory chip 52. The memory chip 52 is a flash memory, for example, and stores image data and correction data configured by the control IC 51.

  The control IC 51 is provided with an image data correction circuit. This correction circuit has a function of correcting the brightness deviation inherent in the image sensor 2, and a function of removing noise included in the image data. The correction unique to the image sensor 2 is performed, for example, by using the correction data stored in advance in the memory chip 52 to set the digitized image data to an appropriate level. This correction is performed for two or three levels of white and black.

  Removal of noise included in the image data is performed by averaging using image data captured a plurality of times. For example, when the gradation of each pixel is expressed by 12 bits, a 15-bit storage area is set for each pixel in the memory chip 52. Data of each pixel for a total of 8 times is added to the storage area. Then, the data stored in the upper 12 bits of the storage area is extracted as pixel data. As a result, image data obtained by averaging the imaging results of eight times is obtained. When a defective pixel is detected in the image data, an interpolation process using a plurality of pixel data around the defective pixel is performed, and the processed pixel data is used instead of the defective pixel.

  Data transmission / reception between the control IC 51 and the memory chip 52 is performed by 1-bit serial input / output. As a result, the number of wires connecting the control IC 51 and the memory chip 52 can be reduced.

  The case 60 has a resin box shape and accommodates the image sensor module A1 and the two reflecting members 63. The cover 61 is attached to the case 60 so as to be rotatable, and serves to hold the document Dc. The transparent plate 62 is made of, for example, a transparent resin and is attached to the case 60. The transparent plate 62 is a portion for placing the document Dc in a flat state.

  The two reflecting members 63 are attached to the inner surfaces on both sides of the case 60 with the image sensor module A1 interposed therebetween. The reflecting member 63 is made of, for example, aluminum and has a surface with high reflectivity. The reflection member 63 is configured to reflect light from the plurality of LED elements 41B, 41R, and 41G and to spread the light in the vertical and horizontal directions in FIG.

  Next, operations of the image sensor module A1 and the image reading device B1 will be described.

  According to the present embodiment, it is possible to collectively capture the description content of the document Dc by the image sensor 2. For this reason, unlike the configuration according to the prior art described above, there is no need to relatively scan the document Dc and the image sensor module A1. Therefore, the description content of the document Dc can be captured as image data in a very short time. Further, it is not necessary to provide the image reading device B1 with a mechanism for scanning the image sensor module A1 or the document Dc. Therefore, the image reading apparatus B1 can be reduced in size and cost.

  The lens unit 3 includes a diverging lens group in which the entrance surfaces 31Aa, 31Ba, and 31Ca are aspherical surfaces whose curvature increases from the center toward the periphery as described above, and the exit surface is substantially concave. Therefore, it is possible to form an image with a wide angle and little distortion. Thereby, it is possible to arrange the lens unit 3 at a position relatively close to the document Dc. Accordingly, the image reading device B1 can be thinned.

  Since the image sensor module A1 is configured using the long rectangular substrate 1, the image sensor module A1 does not have a two-dimensionally expanded shape as shown in FIG. This is advantageous for securing a space for mounting other electronic components in the case 60 of the image reading apparatus B1.

  By disposing a plurality of LED elements 41B, 41G, 41R near both ends of the substrate 1, it is possible to illuminate portions near both ends of the document Dc with relatively high illuminance. Since the lens unit 3 has a wide angle, the amount of light at the light receiving unit 20 decreases as it approaches the edge of the angle of view. By illuminating both ends of the document Dc with high illuminance, it is possible to avoid a shortage of light in the vicinity of the end of the light receiving unit 20. Therefore, it is suitable for capturing image data with uniform brightness. Further, the light from the plurality of LED elements 41B, 41G, 41R can be spread over the entire surface of the document Dc by the reflecting member 63. This is preferable for making the image data uniform in brightness.

  FIG. 5 shows a second embodiment of the image sensor module and the image reading apparatus according to the present invention. In the figure, the same or similar elements as those in the above-described embodiment are denoted by the same reference numerals as those in the above-described embodiment. The image reading apparatus B2 of the present embodiment is not provided with the above-described reflecting member 63. On the other hand, two prisms 41 are provided in the image sensor module A2. These points are different from the above-described embodiment.

  The two prisms 41 are respectively arranged above the LED elements 40B, 40G, and 40R in the drawing. The prism 41 is made of, for example, a transparent resin, and is configured to be able to emit light toward the entire surface of the document Dc by transmitting and refracting light from the LED elements 40B, 40G, and 40R. Further, the LED elements 40B, 40G, 40R and the prism 41 are arranged closer to the lens unit 3 than the side surface of the case 60. Thereby, the board | substrate 1 of this embodiment is made into the longitudinal direction dimension smaller than the board | substrate 1 of embodiment mentioned above.

  Also according to such an embodiment, it is possible to appropriately illuminate the entire surface of the document Dc, and the description content of the document Dc can be read as clear image data. It is also possible to illuminate a desired portion of the document Dc with particularly high illuminance by appropriately changing the shape of the prism 41. In addition, by reducing the size of the substrate 1 in the longitudinal direction, it is possible to reduce the size of the image reading device B1 and to secure a mounting space for electronic components other than the image sensor module A2.

  The image sensor module and the image reading apparatus according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the image sensor module and the image reading apparatus according to the present invention can be varied in design in various ways.

  As a board | substrate said by this invention, it may replace with a printed wiring board and may use what is called a rigid board | substrate or a ceramic board | substrate. The imaging element is not limited to what is called a CCD type and a CMOS type, and any imaging element may be used as long as it can capture two-dimensional light collectively. The configuration of the lens unit is not limited to the above-described embodiment. The number of lenses included in the lens unit and the specifications of each lens can be changed as appropriate, as long as the image can be formed with a wide angle and small distortion. The light emitting means is not limited to a plurality of LED elements, and may be any configuration that can appropriately illuminate the reading object.

1 is a cross-sectional view illustrating a first embodiment of an image sensor module and an image reading apparatus according to the present invention. It is sectional drawing which follows the II-II line | wire of FIG. It is the perspective view and principal part enlarged view which show the image pick-up element used for the image sensor module shown in FIG. It is sectional drawing which shows the lens unit used for the image sensor module shown in FIG. It is sectional drawing which shows 2nd Embodiment of the image sensor module and image reading apparatus which concern on this invention. It is sectional drawing which shows an example of the conventional image sensor module and an image reading apparatus.

Explanation of symbols

A1, A2 Image sensor modules B1, B2 Image reading device Dc Document 1 Substrate 2 Image sensor (photoelectric conversion means)
3 Lens unit (optical system)
4 Light emitting means 20 Light receiving portion 20a Light receiving element 30 Holder 31 Lens groups 31A, 31B, 31C, 31D, 31E, 31F Lenses 31Aa, 31Ba, 31Ca Aspherical incident surface 32 Filters 40B, 40G, 40R LED elements (light sources)
41 Prism 51 Control IC
52 Memory chip 60 Case 61 Cover 62 Transparent plate 63 Reflecting member

Claims (8)

A substrate,
A light emitting means mounted on the substrate and emitting light to the reading object;
Photoelectric conversion means mounted on the substrate and receiving the light reflected by the reading object;
An optical system mounted on the substrate and forming an image of the reading object on the photoelectric conversion means;
An image sensor module comprising:
The photoelectric conversion means is an imaging device including a plurality of light receiving elements arranged in a matrix,
The optical system includes a lens group including a lens having an aspherical surface whose curvature increases as the incident surface moves from the center toward the periphery, thereby forming an image with a wide angle and small distortion. An image sensor module which is a unit. The substrate has a long rectangular shape,
The image sensor and the lens unit are disposed near the center of the substrate,
The image sensor module according to claim 1, wherein the light emitting unit includes a pair of light sources disposed near both ends of the substrate.   The image sensor module according to claim 2, wherein each of the light sources includes a plurality of LED elements.   The image sensor module according to claim 1, wherein the lens unit includes the lens group having an angle of view of 150 ° or more, and the distortion is ± 2% or less. The lens group includes a diverging lens group composed of a plurality of diverging lenses,
5. The divergent lens according to claim 4, wherein the diverging lens is a concave lens, an aspherical surface whose curvature increases as the incident surface of each concave lens moves from the center toward the peripheral portion, and the exit side is substantially a concave spherical surface. Image sensor module.   The image sensor module according to claim 5, wherein the diverging lens group includes three diverging lenses.   An image reading apparatus comprising the image sensor module according to claim 1.   The image reading apparatus according to claim 7, further comprising a reflecting member or a prism disposed at a position separated from the light emitting unit with respect to the lens unit.

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