JP2009092742A - Light guide element and image sensor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light guide element making quantity of light in each section of linear light emitted from a light outgoing face uniform as much as possible and to provide an image sensor module provided with this light guide element. <P>SOLUTION: This light guide element 4 is provided with: a light incoming face 4A extended linearly on the whole, formed into a substantially circular column shape, and provided in an end part in the longitudinal direction x; a light reflection face 4B extended in the longitudinal direction x and reflecting the light incoming from the light incoming face 4A toward the opposing outgoing direction z'; and the light outgoing face 4C letting the light coming from the light reflection face 4B go out as linear light extending in the longitudinal direction x. The light reflection face 4B is composed of a plurality of plane parts 43 and a plurality of concave parts 44 arranged alternately along the longitudinal direction x. A plurality of concave parts 44 are formed into faces scattering light more than a plurality of plane parts 43. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light guide used for, for example, a flatbed scanner and an image sensor module.

    FIG. 8 shows an example of a conventional light guide and an image sensor module using the same (for example, see Patent Document 1). The image sensor module X shown in the figure includes a substrate 91, a light source module 92, a plurality of sensor IC chips 93, a light guide 94, and a case 95. The substrate 91 is an insulating substrate, and a plurality of sensor IC chips 93 are arranged in the main scanning direction x. The light source module 92 includes an LED chip 92a that emits red light, green light, and blue light.

  The light guide 94 has a rod shape extending in the main scanning direction x, and is made of, for example, a transparent acrylic resin. The light guide 94 is formed with a light incident surface 94a, a light reflecting surface 94b, and a light emitting surface 94c. Light emitted from the light source module 92 is incident from the light incident surface 94a. The light reflecting surface 94b is configured such that a plurality of tapered concave surfaces extending in a direction perpendicular to the main scanning direction x are arranged at a predetermined pitch in the main scanning direction x. The light traveling in the light guide 94 is reflected toward the light exit surface 94c by these concave portions of the light reflecting surface 94b. Linear light extending in the main scanning direction x is emitted from the light emitting surface 94c. By irradiating the reading object with the linear light, the reflected light is received by the sensor IC chip 93. Thereby, the content described in the reading object can be taken in as electronic data.

  In the image sensor module X having the above configuration, the light reaching the concave surface portion of the light reflecting surface 94b is reflected by the tapered surface of the concave surface portion and travels in a substantially constant direction. If it does so, the linear light radiate | emitted from the light-projection surface 94c will have the peak of several light quantity equivalent to the pitch of a concave surface part. When such a linear light is applied to the reading object, the illuminance of the entire length of the reading object in the main scanning direction x varies greatly. For example, vertical stripes appear in an image obtained by reading the reading object. There was a thing.

JP-A-9-275469

  The present invention has been conceived under the circumstances described above, and a light guide body in which the amount of light of the linear light emitted from the light emitting surface is made more uniform, and the light guide body It is an object of the present invention to provide an image sensor module including the above.

  The light guide provided by the first aspect of the present invention extends linearly as a whole and is formed in a substantially cylindrical shape, and has a light incident surface provided at a longitudinal end portion thereof and the longitudinal direction. A light reflecting surface that extends and reflects light incident from the light incident surface toward an opposite emitting direction, and light emission that emits light traveling from the light reflecting surface as linear light extending in the longitudinal direction And the light reflecting surface is composed of a plurality of plane portions and a plurality of concave portions alternately arranged along the longitudinal direction, and the plurality of concave portions. Is formed on a surface that scatters light rather than the plurality of flat portions.

  According to such a configuration, since the light reflected by the plurality of concave portions is dispersed by scattering, the amount of light at each place of the linear light emitted from the light emitting surface becomes nearly uniform.

  In preferable embodiment of this invention, white coating is given to the said several concave surface part. In this case, for example, if the plurality of plane portions are mirror-like, the plurality of concave portions become surfaces that scatter light more than the plurality of plane portions. Moreover, in other preferable embodiment of this invention, the said several concave surface part is made into the fine rough surface. Even in this case, when the plurality of flat surface portions are mirror-like, the plurality of concave surface portions are surfaces that scatter light more than the plurality of flat surface portions.

  In a preferred embodiment of the present invention, the light guide is further provided with protruding pieces that are perpendicular to the longitudinal direction and project in a direction different from the emission direction on both side surfaces sandwiching the emission direction. It has been.

  The image sensor module provided by the second aspect of the present invention accommodates the light guide provided by the first aspect of the present invention, the light source module facing the light incident surface, and the light guide. A case; and a light receiving sensor that is arranged along the longitudinal direction and receives linear light reflected by the reading object. According to such a configuration, the content of the reading object can be read with relatively uniform light. Preferably, when the convex piece is provided on the light guide, the case extends in the longitudinal direction and is formed with a groove that fits the convex piece of the light guide. . According to such a configuration, the light guide can be easily positioned when assembled to the case.

  Furthermore, in another preferable embodiment, the light source module includes three LED chips that emit red light, green light, and blue light, and the three LED chips are arranged in series in the emission direction. ing. According to such a configuration, the irradiation range of the red light, the green light, and the blue light emitted from the light source module is unduly dispersed along a direction orthogonal to both the emission direction and the longitudinal direction. Can be prevented.

  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 to 3 illustrate an example of an image sensor module according to the present invention, and FIGS. 4 to 7 illustrate an example of a light guide according to the present invention. The image sensor module A of this embodiment includes a substrate 1, a light source module 2, a plurality of sensor IC chips 3, a light guide 4, a lens array 5, and a case 6. As shown in FIG. 2, the image sensor module A reads the description content of the document Dc as image data while being relatively moved in the sub-scanning direction y with respect to the document Dc placed on the document table St, for example. It is structured as a thing.

  As shown in FIGS. 1 and 2, the substrate 1 is made of ceramic such as alumina or aluminum nitride, and has a long rectangular shape with the main scanning direction x as the long side direction and the sub-scanning direction y as the short side direction. Yes. The substrate 1 is attached to the lower end of the case 6 and is positioned with respect to the case 6. A plurality of sensor IC chips 3 are mounted on the substrate 1.

  The light source module 2 includes a light source substrate 20, a plurality of terminals 21, three LED chips 22, and a case 23. The light source substrate 20 has a rectangular shape, and is made of, for example, ceramic. Alternatively, the light source substrate 20 is made of a composite material of a reinforcing member and a polyimide resin, or a glass epoxy resin. The plurality of terminals 21 are for connecting the light source module 2 to the substrate 1. Each terminal 21 has a clip shape at one end. Each terminal 21 is attached to the light source substrate 20 by this clip-shaped portion. The three LED chips 22 emit red light, green light, and blue light, for example, and are mounted in series on the light source substrate 20. The case 23 is made of white resin, for example, and surrounds the three LED chips 22.

  The plurality of sensor IC chips 3 are semiconductor chips each having a rectangular shape in plan view, each having a light receiving portion (not shown), and is an example of a light receiving sensor referred to in the present invention. The plurality of sensor IC chips 3 are mounted on the substrate 1 along the main scanning direction x, and are arranged immediately below the lens array 5 as shown in FIG. The sensor IC chip 3 has a photoelectric conversion function and is configured to output an image signal having an output level corresponding to the amount of received light.

  As shown in FIGS. 4 to 7, the light guide 4 is a highly transparent member made of an acrylic resin such as PMMA (polymethyl methacrylate), and has a substantially cylindrical shape having a substantially circular cross section over the entire length. Has been. The light guide 4 is formed by, for example, injection molding using a mold, and has a light incident surface 4A, a light reflecting surface 4B, and a light emitting surface 4C. The light incident surface 4A is a surface for introducing light from the light source module 2 into the light guide 4 as shown in FIG. 1, and is constituted by one end surface of the light guide 4 in the main scanning direction x. . The light incident surface 4A is mirror-finished to prevent light from the light source module 2 from being scattered. In this embodiment, the light incident surface 4A has a gentle convex shape as shown in FIGS. ing. In the present embodiment, the light guide 4 has a total length of about 230 mm and a diameter of about 4 mm.

  The light reflecting surface 4B directs the light traveling along the main scanning direction x from the light incident surface 4A toward the light emitting surface 4C provided to face the light reflecting surface 4B in the direction z ′ (emitting direction). It is a surface for reflecting along. The emission direction z 'coincides with the direction in which the three LED chips 22 are arranged in series. As shown in FIGS. 4 to 7, the light reflecting surface 4 </ b> B is provided at the tip of the convex portion 41. The convex portion 41 has a strip shape with a substantially rectangular cross section extending in the main scanning direction x. The light reflecting surface 4B is constituted by a plurality of flat surface portions 43 and a plurality of concave surface portions 44 arranged alternately. The plurality of concave surface portions 44 are formed every 1 mm along the main scanning direction x. In the present embodiment, as shown in FIG. 7, the flat surface portion 43 is a flat mirror surface, while the concave surface portion 44 is a fine rough surface. This fine rough surface is formed by blasting a part of a mold for forming the light guide 4 by embossing or using metal particles having a particle diameter of 20 μm to 200 μm. Because of such a fine rough surface, the concave surface portion 44 has a higher light scattering function than the flat surface portion 43.

  Instead of forming the concave surface portion 44 as a fine rough surface as described above, the concave surface portion 44 may be formed into a mirror surface similar to the flat surface portion 43 and then white coated. In this case, the white coating is performed by, for example, hot stamping or screen printing.

  As clearly shown in FIGS. 5 and 6, the light guide 4 is formed with a plurality of protruding pieces 42. These convex pieces 42 are provided so as to form a pair on both side surfaces sandwiching the direction z ′, and in the main scanning direction x, a plurality of pairs are positioned at a predetermined interval. The convex piece 42 is projected along a direction perpendicular to the main scanning direction x and perpendicular to the direction z ′, and has a predetermined length in the main scanning direction x. The convex piece 42 only needs to protrude in a direction perpendicular to the main scanning direction x and does not necessarily protrude in a direction perpendicular to the direction z ′. What is necessary is just to protrude in the direction different from direction z 'which is an output direction.

  The light exit surface 4C is a surface that emits light toward the document Dc, and extends in the main scanning direction x. From the light emitting surface 4C, linear light extending in the main scanning direction x is emitted.

  The lens array 5 is for focusing the light reflected by the document Dc on the plurality of sensor IC chips 3 at the same erect magnification. The lens array 5 includes a block-shaped holder extending in the main scanning direction x and a plurality of lenses arranged along the main scanning direction x. These lenses extend in a direction z whose optical axis is perpendicular to both the main scanning direction x and the sub-scanning direction y.

  The case 6 has a substantially block shape extending in the main scanning direction x, and houses the substrate 1, the light source module 2, the plurality of sensor IC chips 3, the light guide 4, and the lens array 5. As shown in FIGS. 2 and 3, the case 6 includes a recess 61 for housing the light guide 4, a groove 62 used for positioning the light guide 4, and the light guide 4 falling off. A stopper portion 63 is formed to prevent this. The recess 61 has a width larger than the diameter of the light guide 4 and opens upward over the entire length in the main scanning direction x. The groove 62 has a shape in which the convex piece 42 of the light guide 4 can be fitted, and when the convex piece 42 is fitted, the outgoing direction (direction z ′) has a constant posture inclined with respect to the vertical direction. It is provided to become. The stopper portion 63 is provided at a portion corresponding to one convex piece 42 of the light guide 4. The stopper portion 63 locks the convex piece 42 so that the light guide 4 is held in a fixed posture.

  Next, the operation of the light guide 4 having the above configuration and the image sensor module A including the light guide 4 will be described.

  According to this embodiment, the light emitted from the light source module 2 and traveling through the light guide 4 is reflected by the light reflecting surface 4B and emitted from the light emitting surface 4C. Since the light reflecting surface 4B has the concave surface portion 44 arranged every 1 mm, more light can be reflected toward the light emitting surface 4C. Moreover, since the concave surface portion 44 is a fine rough surface that scatters light, the light that is reflected by the concave surface portion 44 and travels toward the light exit surface 4C is dispersed. For this reason, the linear light emitted from the light emitting surface 4C is in a state in which the amount of light at each place is substantially uniform over the entire length region in the main scanning direction x and the sub-scanning direction y. Therefore, it is possible to read the description content of the document Dc as image data having a uniform color tone.

  In the present embodiment, since the light reflecting surface 4B is provided at the tip of the convex portion 41, the boundary between the light reflecting surface 4B and other portions is also provided in the light guide 4 having a substantially circular cross section. Can be accurately defined. This is suitable for making the amount of light of the linear light emitted from the light emitting surface 4C uniform.

  Furthermore, in this embodiment, in the case 6 that accommodates the light guide 4, a groove 62 that fits into the convex piece 42 of the light guide 4 and a stopper 63 that locks the convex piece 42 are formed. Thereby, the light guide 4 having a circular cross section can be reliably positioned with respect to the case 6 in a fixed posture. Therefore, the desired relative positional relationship between the light guide 4 and the light source module 2 attached to the case 6 is always maintained. This is suitable for making the amount of light of the linear light from the light exit surface 4C uniform.

  Furthermore, in this embodiment, three LED chips 22 are arranged in series in the direction z ′. For this reason, it is possible to prevent the irradiation range of the red light, the green light, and the blue light from being unduly shifted in the direction y ′ perpendicular to the direction z ′.

  The light guide and the image sensor module according to the present invention are not limited to the above-described embodiments. The specific configuration of each part of the light guide and the image sensor module according to the present invention can be variously changed in design.

It is principal part sectional drawing which shows an example of the image sensor module which concerns on this invention. It is sectional drawing which follows the II-II line of FIG. It is sectional drawing which follows the III-III line of FIG. It is principal part sectional drawing which shows an example of the light guide which concerns on this invention. It is a principal part bottom view which shows an example of the light guide which concerns on this invention. It is sectional drawing which follows the VI-VI line of FIG. It is sectional drawing which follows the VII-VII line of FIG. It is principal part sectional drawing which shows an example of the conventional image sensor module.

Explanation of symbols

A Image sensor module Dc Document (reading object)
St Document placement table x Main scanning direction (longitudinal direction)
y Sub-scanning direction y 'direction z direction z' direction (outgoing direction)
1 Substrate 2 Light source module 3 Sensor IC chip (light receiving sensor)
4 Light guide 5 Lens array 6 Case 20 Light source substrate 21 Terminal 22 LED chip 41 Convex part 42 Convex piece 43 Flat part 44 Concave part 4A Light incident surface 4B Light reflecting surface 4C Light emitting surface 62 Groove part

Claims (7)

It extends in a straight line as a whole and is formed in a substantially cylindrical shape.
A light incident surface provided at an end in the longitudinal direction, a light reflecting surface that extends in the longitudinal direction and reflects light incident from the light incident surface toward an opposite emitting direction, and travels from the light reflecting surface A light emitting surface that emits the emitted light as linear light extending in the longitudinal direction,
The light reflecting surface is composed of a plurality of plane portions and a plurality of concave portions alternately arranged along the longitudinal direction, and the plurality of concave portions scatter light more than the plurality of plane portions. A light guide formed on a surface.   The light guide according to claim 1, wherein white coating is applied to the plurality of concave surface portions.   The light guide according to claim 1, wherein the plurality of concave portions are fine rough surfaces.   The guide according to any one of claims 1 to 3, further comprising a projecting piece projecting in a direction perpendicular to the longitudinal direction and different from the emitting direction on each of both side surfaces sandwiching the emitting direction. Light body.   5. The light guide according to claim 1, a light source module that faces the light incident surface, a case that accommodates the light guide, and an array along the longitudinal direction. An image sensor module, comprising: a light receiving sensor that receives the reflected linear light. The light guide according to claim 4, a light source module facing the light incident surface, a case accommodating the light guide, and a linear shape arranged along the longitudinal direction and reflected by a reading object A light receiving sensor for receiving light,
The image sensor module according to claim 1, wherein the case is formed with a groove portion that extends in the longitudinal direction and fits with the convex piece of the light guide. The light source module includes three LED chips that emit red light, green light, and blue light.
The image sensor module according to claim 5, wherein the three LED chips are arranged in series in the emission direction.

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