JP2009177548A - Image sensor module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image sensor module capable of obtaining more uniform linear light. <P>SOLUTION: The image sensor module A includes a light source 6, a light guide 3 which projects light from the light source 6 toward an object to be read in the form of linear light extending in a main scanning direction, reflectors 2A and 2B which extend in the main scanning direction and are situated across the light guide 3 in a direction orthogonal to the projection direction of the linear light, a photodetection means 7 of receiving the linear light reflected by the object to be read, and a case 1 which contains the light source 6, the light guide 3, reflectors 2A and 2B, and the photodetection means 7, and has spaces 21a and 21b extending in the main scanning direction between the light guide 3 and the reflectors 2A and 2B. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image sensor module used for, for example, a scanner or a bill reading device.

  2. Description of the Related Art Image sensor modules having a function of irradiating a document or a bill with linear light and a function of reading reflected light are widely used in scanners and bill readers. FIG. 4 shows an example of a conventional image sensor module. The image sensor module X shown in the figure has a configuration in which reflectors 92A and 92B, a light guide 93, a lens unit 94, a substrate 95, an LED module 96, a sensor chip 97, and a glass plate 98 are accommodated in a case 91. And has an outer shape extending in the main scanning direction perpendicular to both the sub-scanning direction y and the height direction z.

  The light from the LED module 96 travels in the light guide 93 in the main scanning direction. The light guide 93 is formed with a reflecting portion 93a and an exit surface 93b. The reflection part 93a is composed of, for example, a plurality of grooves arranged at equal pitches, and reflects the light traveling in the light guide 93 toward the emission surface 93b. Linear light extending in the main scanning direction is emitted from the emission surface 93b. The reflectors 92 </ b> A and 92 </ b> B are made of a material having a relatively high reflectance such as a white resin, for example, and are for preventing light from leaking from the light guide 93. The reflectors 92A and 92B are in close contact with the light guide 93 and sandwich the light guide 93. The linear light is reflected on the original and then imaged on the sensor chip 97 by the lens unit 94. The sensor chip 97 is disposed on the substrate 95 along the main scanning direction. Thereby, the content printed on the document can be read as image data.

  However, there is a strong demand for downsizing the image sensor module X. It is directed to reduce the dimensions in the sub-scanning direction y and the height direction z while achieving the function of reading documents of the same width. For this reason, reflector 92A, 92B becomes a relatively elongate shape. If the reflectors 92A and 92B are thermally deformed or an external force is generated during assembly, the light guide 93 and the reflectors 92A and 92B may not be in close contact with each other. The amount of light reflected into the light guide 3 by the reflectors 92A and 92B is different between a portion where the light guide 93 and the reflectors 92A and 92B are in close contact with each other, and a portion where the light guide 93 is not in close contact. For this reason, the amount of reflection of light by the reflectors 92A and 92B varies along the main scanning direction, and the amount of the linear light may vary along the main scanning direction.

JP 2000-125080 A

  The present invention has been conceived under the circumstances described above, and an object thereof is to provide an image sensor module capable of obtaining more uniform linear light.

  The image sensor module provided by the present invention extends in the main scanning direction, a light source, a light guide that emits light from the light source as linear light extending in the main scanning direction toward the reading target, A reflector that sandwiches the light guide in a direction perpendicular to the emission direction of the linear light, a light receiving means that receives the linear light reflected by the reading object, the light source, the light guide, the reflector, And a case for accommodating the light receiving means, wherein a space extending along the main scanning direction is provided between the light guide and the reflector. .

  According to such a configuration, since a space is provided between the light guide and the reflector, even when the reflector is deformed, the amount of light reflected by the reflector changes along the main scanning direction. It is difficult to do. Therefore, such an image sensor module can obtain more uniform linear light along the main scanning direction.

  In a preferred embodiment of the present invention, the space is provided so as to sandwich the light guide from both sides in a direction orthogonal to the emission direction of the linear light. According to such a configuration, the amount of light reflected by the reflector is less likely to change along the main scanning direction, and more uniform linear light can be obtained along the main scanning direction.

  In a preferred embodiment of the present invention, the space is provided over substantially the entire length of the reflector along the main scanning direction. According to such a configuration, the amount of light reflected by the reflector is less likely to change along the main scanning direction, and more uniform linear light can be obtained along the main scanning direction.

  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 an example of an image sensor module according to the present invention. The image sensor module A of this embodiment includes a case 1, reflectors 2 </ b> A and 2 </ b> B, a light guide 3, a lens unit 4, a substrate 5, an LED module 6, a sensor chip 7, and a glass plate 8. The image sensor module A has a reading width of about 100 mm, and is suitable for use in a banknote reading device that reads banknotes that move relative to each other in the sub-scanning direction y. The image sensor module A can set the reading width to, for example, 50 mm or 200 mm by changing the main scanning direction x dimension.

  The case 1 includes reflectors 2A and 2B, a light guide 3, a lens unit 4, a substrate 5, an LED module 6, a sensor chip 7 and a glass plate 8, and has a substantially rectangular parallelepiped shape extending in the main scanning direction x. ing. Moreover, the case 1 is opened up and down in the height direction z, and the glass plate 8 is fitted in the upper part and the substrate 5 is fitted in the lower part. As shown in FIG. 2, a linear light source accommodation space 11 is formed in the case 1. The linear light source accommodation space 11 extends in the main scanning direction x and opens in the direction z. The linear light source accommodation space 11 accommodates the reflectors 2A and 2B and the light guide 3 constituting the linear light source. The linear light source accommodation space 11 is provided with a recess 11a. The recess 11a has a relatively shallow bottom shape that is rectangular in plan view. Case 1 is formed of, for example, a black resin.

  The light guide 3 is made of a transparent resin such as methyl methacrylate resin (PMMA), for example, and emits light from the LED module 6 as linear light extending in the main scanning direction x. As shown in FIG. 3, the light guide 3 has a structure in which a pyramid portion 31 and a flat portion 32 are combined. , 3f. In the present embodiment, the pyramid portion 31 and the flat portion 32 are arranged such that the center lines of each other form an angle of about 40 °. In this embodiment, the direction y dimension of the pyramid portion 31 is about 3.8 mm, the direction z dimension is about 4.7 mm, and the direction x dimension is about 60 mm. The flat portion 32 has a thickness of about 1.7 mm and a height of about 8 mm.

  The incident surface 3 a faces the direction z and is located in front of the LED module 6. The inclined surface 3b is a surface for traveling in the main scanning direction x by reflecting the light incident from the incident surface 3a. The reflecting portion 3 c extends in the main scanning direction x and is located at the lower end of the flat portion 32. The reflection portion 3c is a portion that reflects the light traveling in the main scanning direction x in the light guide 3 to the exit surface 3d. The reflection part 3c is comprised by the some groove | channel, for example. The plurality of grooves are arranged at an equal pitch in the main scanning direction x, and the larger the distance from the inclined surface 3b, the larger the size. As shown in FIG. 3, the exit surface 3 d extends in the main scanning direction x and is provided at the upper end of the flat portion 32. The side surfaces 3e and 3f are a pair of side surfaces that face each other and connect the reflecting portion 3c and the emission surface 3d, and both extend along the main scanning direction.

  The reflectors 2A and 2B are for preventing the light traveling in the light guide 3 from being unreasonably leaked, and are made of, for example, white resin. As shown in FIG. 3, the reflectors 2 </ b> A and 2 </ b> B extend in the main scanning direction x and sandwich and hold the light guide 3.

  The reflector 2A has a light guide housing space 21 as shown in FIG. The light guide housing space 21 is formed larger than the light guide 3, and a space 21a is formed between the light guide 3 and the side surface 3e in a state in which the light guide 3 is housed. The space 21a extends over substantially the entire length along the main scanning direction x of the reflector 2A. Further, as shown in FIG. 3, the reflector 2 </ b> A has a recess 22 and a bottom plate 23. The recess 22 is located near one end in the main scanning direction x of the reflector 2A, and is recessed in the sub-scanning direction y. The bottom plate 23 defines the lower end of the light guide housing space 21 and has a strip shape extending in the main scanning direction x.

  As shown in FIG. 3, the reflector 2 </ b> B has a band plate shape standing in the direction z as a whole. A convex portion 25 and a tongue portion 26 are formed on the reflector 2B. The convex part 25 protrudes in the sub-scanning direction y and fits into the concave part 22 of the reflector 2A. The tongue portion 26 has a thin plate shape extending in the sub-scanning direction y. In a state where the reflectors 2 </ b> A and 2 </ b> B are combined with the light guide 3 interposed therebetween, the tongue portion 26 is located on the lower side of the bottom plate 23. As shown in FIG. 2, in a state where the reflectors 2 </ b> A and 2 </ b> B and the light guide 3 are accommodated in the case 1, the tongue 26 is fitted into the recess 11 a. The reflector 2 </ b> B is provided to reflect light leaking from the light guide 3 into the light guide 3 at a portion near the LED module 6 of the light guide 3.

  A space 21b is formed so as to be sandwiched between the reflector 2B, the bottom plate 23 of the reflector 2A, and the side surface 3f of the light guide 3. The space 21b is provided over substantially the entire length of the reflector 2B along the main scanning direction x. The space 21b is arranged on the opposite side of the space 21a with the light guide 3 interposed therebetween in a direction orthogonal to the emission direction of the linear light.

  The lens unit 4 is an optical component that forms an image on the sensor chip 7 with linear light reflected by the document. The lens unit 4 has a configuration in which, for example, a plurality of cylindrical lenses arranged in the main scanning direction x are held in a resin housing.

  The substrate 5 is made of, for example, ceramic or glass epoxy resin, and the LED module 6 and the sensor chip 7 are mounted thereon. The substrate 5 is fitted in the lower part of the case 1 and is fixed by, for example, a plurality of metal fittings (not shown).

  The LED module 6 is a light source of the image sensor module A and includes, for example, LED chips that emit red light, blue light, and green light. The LED module 6 is mounted on the substrate 5 so as to face the incident surface 3a.

  The sensor chip 7 is arranged to extend in the main scanning direction x, generates an electromotive force corresponding to the received light, and further outputs a luminance signal for each pixel from the electromotive force. By receiving the light reflected by the document by the sensor chip 7, the description content of the document can be read as image data.

  The glass plate 8 is a rectangular flat plate made of glass and covers the reflector 2 </ b> A and the lens unit 4. For example, a bill to be read is slid on the glass plate 8.

  Next, the operation of the image sensor module A will be described.

  According to this embodiment, the light guide 3 has the side surface 3e and the reflector 2A separated in advance by the space 21a over substantially the entire length along the main scanning direction x. For this reason, even when the reflector 2A is thermally deformed or an external force is applied, the amount of light reflected by the reflector 2A to the light guide 3 does not change along the main scanning direction x. Further, the reflector 2B disposed near the LED module 6 and the light guide 3 are also separated by a space 21b. For this reason, even when the reflector 2B is thermally deformed or an external force is applied, the amount of light reflected by the reflector 2B to the light guide 3 does not change along the main scanning direction x. Therefore, the amount of linear light emitted from the exit surface 3d of the light guide 3 is uniform over substantially the entire length along the main scanning direction x.

  Since reading can be performed with such uniform linear light, the image sensor module A can obtain a preferable read image. Further, the image sensor module A can be easily downsized because the uniformity of the linear light is not impaired by thermal deformation or deformation due to external force.

  The image sensor module according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the image sensor module according to the present invention can be varied in design in various ways. For example, in the above embodiment, the spaces 21a and 21b are provided between the side surfaces 3e and 3f of the light guide 3 and the reflectors 2A and 2B, but only one of the spaces 21a and 21b is provided. However, the effect of the present invention can be obtained.

  In the above embodiment, the reflector 2B is formed shorter than the light guide 3 along the main scanning direction x, but the reflector 2B may have a length equivalent to that of the light guide 3. In that case, it is preferable that the space 21b is provided over substantially the entire length of the light guide 3 along the main scanning direction.

It is a top view which shows an example of the image sensor module concerning this invention. It is sectional drawing which follows the II-II line | wire of FIG. It is a perspective view which shows the reflector and light guide used for the image sensor module shown in FIG. It is sectional drawing which shows an example of the conventional image sensor module.

Explanation of symbols

A Image sensor module x Main scanning direction y Sub scanning direction z Height direction 1 Case 2A, 2B Reflector 3 Light guide 3a Incident surface 3b Inclined surface 3c Reflecting portion 3d Emission surface 3e, 3f Side surface 4 Lens unit 5 Substrate 6 LED module (light source)
7 Sensor chip (light receiving means)
DESCRIPTION OF SYMBOLS 11 Linear light source accommodation space 21 Light guide accommodation space 21a, 21b Space 22 Concave part 23 Bottom plate 25 Convex part 26 Tongue part 31 Pyramid part 32 Flat part

Claims (3)

A light source;
A light guide that emits light from the light source as linear light extending in the main scanning direction toward the reading target;
A reflector extending in the main scanning direction and sandwiching the light guide in a direction orthogonal to the emission direction of the linear light;
A light receiving means for receiving the linear light reflected by the reading object;
A case housing the light source, the light guide, the reflector, and the light receiving means;
An image sensor module comprising:
An image sensor module, wherein a space extending along the main scanning direction is provided between the light guide and the reflector.   2. The image sensor module according to claim 1, wherein the space is provided so as to sandwich the light guide from both sides in a direction orthogonal to an emission direction of the linear light.   The image sensor module according to claim 1, wherein the space is provided over substantially the entire length of the reflector along the main scanning direction.

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