JP2019118053A - Lighting device and image sensor unit - Google Patents

Abstract

To provide an advantageous technique for suppressing variations in illuminance distribution in a lighting device.SOLUTION: A lighting device 100 includes a light source 101, and a rod-like light guide 102 having a light incident surface 111 on which light from a light source is incident at least at one end and a light emitting surface 112 extending in the longitudinal direction for emitting the light, and the light guide 102 includes a diffuse reflection area 115 that is disposed in a part of the light emitting surface 112 side of the light guide 102 and a part of the light incident surface 111 side in the longitudinal direction and in which light is diffused and reflected so as to spread, and the lighting device 100 further includes a diffusion member 103, and the diffusion member 103 is disposed on the light emitting surface 112 in the longitudinal direction of the light guide 102 so as to diffuse the light emitted from the light source 101 and the light emitting surface 112.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a lighting device and an image sensor unit.

  A lighting device used for a contact image sensor (CIS) or the like is required to make the illuminance distribution in the longitudinal direction (main scanning direction) more uniform. In Patent Document 1, a strip-shaped region extending in the longitudinal direction is formed in a part of the circumferential surface of the light guide, and radial fine bodies having protrusions extending radially from a reference point are two-dimensionally arrayed in the strip-shaped region. It has been shown that the light distribution makes the illuminance distribution uniform.

International Publication 2016/133216 JP, 2015-154120, A

  According to Patent Document 1, the radial fine bodies are coarsely arranged in the vicinity of the light source element at a position opposite to the light emitting surface of the light guide, and denser as they are farther from the light source element. It has been shown to ensure uniformity. However, design such as the shape of the radial fine bodies and the arrangement of the radial fine bodies may be complicated and may cause local variations in brightness. In addition to the main scanning reflection pattern disposed opposite to the emission surface in Patent Document 2, a light guide having a sub-scanning reflection pattern disposed on the side of the emission surface is disclosed in order to improve the uniformity of the illuminance distribution. It is shown. The sub-scanning reflection pattern is disposed in the vicinity of the incident surface on which light is incident, but there may be variations in the illuminance distribution between the portion where the sub-scanning reflection pattern is disposed and the portion where it is not disposed.

  An object of the present invention is to provide an advantageous technique for suppressing variations in illuminance distribution in a lighting device.

  In view of the above problems, a lighting device according to an embodiment of the present invention extends in the longitudinal direction to emit light, and a light source, an incident surface on which light from the light source is incident on at least one end portion, and And a rod-like light guide provided with a light exit surface, wherein the light guide is a part of the light exit surface of the light guide and a part of the light entrance surface in the longitudinal direction. The illumination apparatus further includes a diffusion member, and the diffusion member guides the light emitted from the light emission surface to the light emission surface so as to diffuse the light. It is characterized by being disposed along the longitudinal direction of the light.

  By the above means, in the lighting device, an advantageous technique is provided to suppress variations in the illuminance distribution.

The figure explaining the outline of the lighting installation concerning the embodiment of the present invention. The figure explaining the outline of the support method of the spreading | diffusion member of the illuminating device of FIG. The figure explaining the outline of the image sensor unit in which the lighting installation of Drawing 1 was built.

  Hereinafter, specific embodiments of the illumination device according to the present invention will be described with reference to the attached drawings. Each drawing is only a schematic drawing described for the purpose of describing the structure or configuration, and the dimensions of the illustrated members do not necessarily reflect the actual ones. Further, in the following description and the drawings, the common configuration is given the same reference numeral throughout the plurality of drawings. Therefore, the common configuration will be described with reference to a plurality of drawings, and the description of the configuration having the same reference numeral will be omitted as appropriate.

  A lighting device 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 (a) and 1 (b) are diagrams schematically showing the lighting device 100 of the present embodiment. The illumination device 100 is used, for example, as a contact image sensor (CIS). Therefore, the lighting apparatus 100 includes a light source 101 for illuminating the object to be illuminated, and a rod-like light guide 102 for guiding light incident from the light source 101 in the longitudinal direction. For the light source 101, for example, a light emitting diode (LED) is used. The light guide 102 has an incident surface 111 on which light from the light source 101 is incident at at least one end, and a longitudinally extending emission surface 112 for emitting the light inside the light guide 102. Equipped with

  The light guide 102 is a diffusive reflection area 115 in which light is diffusely reflected and spread on the side of the light exit surface 112 so that light propagating in the light guide 102 is uniformly emitted from the light exit surface 112. including. The diffuse reflection area 115 is a part of the light exit surface 112 side of the light guide 102, and is disposed on a part of the light entrance surface 111 side in the longitudinal direction. The diffuse reflection area | region 115 may be distribute | arranged from the edge part by the side of the entrance plane 111 by the side of the output surface 112, as FIG. 1 (a), 1 (b) shows. Furthermore, the light guide 102 may include a reflection pattern 113 disposed to face the emission surface 112. For example, as shown in Patent Document 1, in the reflection pattern 113, the radial reflectors 114 may be two-dimensionally arranged. In this case, the pattern density of the reflectors 114 becomes denser as it goes away from the light source 101, whereby uniformity of illumination in the longitudinal direction can be ensured. However, when a point-like pattern such as the reflector 114 is used, a bright spot may occur in the illuminance distribution of the light emitted from the output surface 112. Further, for example, as shown in Patent Document 2, as a reflection pattern 113, a concavo-convex structure or the like is provided in a direction intersecting the longitudinal direction of the light guide 102 at a position facing the light emitting surface 112 of the light guide 102. It is also good. However, when the concavo-convex structure in the direction intersecting the longitudinal direction of the light guide 102 is used, a bright line may occur in the illuminance distribution of light emitted from the emission surface 112. As described above, even when the illuminance distribution generated by the reflection pattern 113 is uneven, the dispersion of the illuminance distribution can be alleviated by providing the diffuse reflection area 115. However, the diffuse reflection area 115 is disposed on a part of the light exit surface 112 side of the light guide 102 closer to the light entrance surface 111. For this reason, in the illuminance distribution of the light emitted from the light emission surface 112, a variation may occur between the portion where the diffuse reflection area 115 is disposed and the portion where the diffuse reflection region 115 is not disposed. As described above, in the case where the brightness distribution locally varies in brightness, a shadow may be generated in the read image in the CIS in which the lighting device 100 is incorporated.

  In the present embodiment, the illumination device 100 further includes the diffusion member 103 in order to suppress the variation in the illuminance distribution. The diffusion member 103 is disposed on the emission surface 112 along the longitudinal direction of the light guide 102 so as to diffuse the light emitted from the emission surface 112. Here, “upper” of the exit surface 112 indicates the direction in which the light emitted from the exit surface 112 of the light guide 102 travels. The diffusing member 103 may be disposed on at least a portion of the light guide 102 and on the light source 101. Further, as shown in FIGS. 1 (a) and 1 (b), the diffusion member 103 includes a portion of the light guide 102 in which the diffuse reflection area 115 is disposed and a portion in which the diffuse reflection area 115 is not disposed. It may be placed on the border of Also, the diffusion member 103 may be disposed on the entire light guide 102. Even if the light output from the exit surface 112 has a variation in the illuminance distribution such as bright spots and bright lines, the diffusing member 103 diffuses the light by the lighting device 100 including the diffusing member 103, and the illuminance distribution Can be suppressed. In addition, when the diffusion member 103 is disposed on the light source 101, it is possible to suppress the variation of the illuminance distribution in the vicinity of the light source 101 having the highest luminance in the lighting device 100.

  For example, when the light guide 102 includes the reflection pattern 113, and the illuminance distribution depending on the distance from the light source 101 is small in the longitudinal direction of the light guide 102, the diffusion degree of the light of the diffusion member 103 is in the longitudinal direction. It may be constant. Since the degree of diffusion of light is constant, the degree of freedom in selecting the diffusion member 103 is increased.

  Further, when there is an illuminance distribution depending on the distance from the light source 101 in the longitudinal direction of the light guide 102, the degree of diffusion of light of the diffusion member 103 may change in the longitudinal direction. In the portion of the light guide 102 near the light source 101, the illuminance of the light emitted from the emission surface 112 may be high. Therefore, the diffusion degree of the light of the diffusion member 103 is farther from the light source 101 of the light guide 102 of the diffusion member 103 than the portion of the diffusion member 103 disposed closer to the light source 101 of the light guide 102. The portion disposed above the portion may be lower. As a result, the variation in the illuminance distribution of the light emitted from the lighting device 100 is reduced. For example, when the light source 101 is disposed at one end of the light guide 102, the diffusion degree of light at the end of the diffusion member 103 where the light source 101 is disposed is the highest, and the side of the diffusion member 103 away from the light source 101 The degree of diffusion of light at the end of the can be the lowest. Also, for example, when the light sources 101 are disposed at both ends of the light guide 102, the diffusion degree of light at both ends of the diffusion member 103 is the highest, and the diffusion degree of light at the center of the diffusion members 103 is the lowest. It can be. The degree of diffusion of light may be gradually changed in a gradation manner or may be changed stepwise.

  As shown in FIGS. 1A and 1B, the diffusion member 103 has a plate shape including a surface 121 facing the light emitting surface and a surface 122 opposite to the surface 121, and is a surface Light may be diffused by at least one of the surface 121 and the surface 122 being rough. For example, the diffusion member 103 may be a plate-like ground glass. In addition, the diffusion member 103 may include particles for scattering light. For example, the diffusion member 103 may be plate-like glass or resin containing milky white particles. Further, for example, the diffusion member 103 may be glass or resin containing inorganic particles such as titanium oxide and barium sulfate. Also, for example, the diffusion member 103 may be ground glass containing particles for scattering light. Further, the degree of diffusion of light described above can be adjusted by the surface roughness of the surfaces 121 and 122 of the diffusion member 103 and the content of particles for scattering light.

  The diffusion member 103 may be spaced apart from the light guide 102 as shown in FIG. 1 (a). In addition, the diffusion member 103 may be in contact with the light guide as shown in FIG. It may be appropriately selected according to the shape and size of the lighting device 100. In addition, the light guide 102 may not include the reflector 114 (the reflection pattern 113). The lighting device 100 includes the light guide 102 provided with at least the diffuse reflection area 115 and the diffusion member 103.

  Moreover, the illuminating device 100 contains the flame | frame 201 which accommodates the light source 101 and the light guide 102, as the perspective view of Fig.2 (a) shows. FIG. 2 (b) shows a cross-sectional view taken along the broken line 200 of FIG. 2 (a). As shown in FIGS. 2A and 2B, the diffusion member 103 may be supported by the frame 201. In the structure shown in FIGS. 2 (a) and 2 (b), the diffusion member 103 is directly coupled to the frame 201, but the diffusion member 103 and the frame 201 are connected via a support member (not shown) or the like. May be combined.

  Hereinafter, as an application example of the illumination device 100 according to the above-described embodiment, an image sensor unit 300 in which the illumination device 100 is incorporated will be exemplarily described. FIG. 3 is a schematic view of an image sensor unit 300 in which the above-described illumination device 100 is incorporated.

  The image sensor unit 300 includes an illumination device 100 for illuminating the object to be illuminated 304, a condenser 302 for condensing the light of the object to be illuminated 304, and a line sensor 303 for receiving the light from the condenser 302. Including. In addition, the image sensor unit 300 includes a sensor frame 301 that houses the illumination device 100, the light collector 302 and the line sensor 303. The diffusion member 103 may be disposed on an area of the light guide 102 corresponding to the effective reading area of the line sensor 303.

  The light emitted from the light guide 102 of the illumination device 100 passes through the diffusion member 103 and is irradiated to the object to be illuminated 304 through the window 305 provided in the sensor frame 301 of the image sensor unit 300. The light irradiated to the object to be illuminated 304 is reflected by the object to be illuminated 304, and enters the line sensor 303 through the window 305 and the condenser 302. At this time, a member having a higher degree of diffusion of light than the diffusion member 103 is not disposed between the diffusion member 103 and the object to be illuminated 304 and between the object to be illuminated 304 and the line sensor 303. That is, the window 305 and the light collector 302 can be made of a material having a lower degree of diffusion of light than the diffusion member 103. For example, the surface of the window 305 may be flatter than the surfaces 121, 122 of the diffusing member 103. Also, for example, the window 305 may not include particles that scatter light as described above.

  In addition, the diffusion member 103 is not limited to being supported by the frame 201 of the lighting device 100 as described above. For example, the diffusion member 103 may be fixed to and supported by the sensor frame 301 via a support member (not shown) or the like.

  As described above, by disposing the diffusion member 103 in the lighting device 100, variation in illuminance distribution such as bright spots and bright lines is suppressed in the light emitted from the lighting device 100. As a result, in the image sensor unit 300 in which the illumination device 100 including the diffusion member 103 is incorporated, the image quality of the acquired image can be improved.

  Although the embodiments and examples according to the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments and examples, and the embodiments described above without departing from the scope of the present invention. Can be changed or combined as appropriate. In addition, the individual terms described in the present specification are merely used for the purpose of describing the present invention, and it goes without saying that the present invention is not limited to the exact meaning of the terms, It may also include its equivalents.

100: illumination device, 101: light source, 102: light guide, 103: diffusion member, 111: entrance surface, 112: exit surface

Claims (16)

A lighting device comprising: a light source; and a rod-like light guide including an incident surface on which light from the light source is incident to at least one end, and a light emitting surface extending in a longitudinal direction to emit light. There,
The light guide is a part of the light-guiding body on the side of the light-exiting surface, and is disposed on a part of the light-incident side in the longitudinal direction, and diffuse-reflecting so as to spread light. Equipped with an area
The lighting device further includes a diffusion member.
The lighting device, wherein the diffusion member is disposed along the longitudinal direction of the light guide on the emission surface so as to diffuse light emitted from the emission surface.   The lighting device according to claim 1, wherein the diffusion member is disposed on at least a part of the light guide and on the light source.   3. The device according to claim 1, wherein the diffusion member is disposed on a boundary between a portion of the light guide where the diffuse reflection area is disposed and a portion where the diffuse reflection area is not disposed. The lighting device described in.   The lighting device according to any one of claims 1 to 3, wherein the diffusion member is disposed on the whole of the light guide.   The lighting device according to any one of claims 1 to 4, wherein a diffusion degree of light of the diffusion member is constant in the longitudinal direction.   The lighting device according to any one of claims 1 to 4, wherein a diffusion degree of light of the diffusion member changes in the longitudinal direction. The light guide has a first portion and a second portion that is further from the light source than the first portion,
The diffusion degree of light of the diffusion member is lower in the portion disposed above the second portion of the diffusion member than in the portion disposed above the first portion of the diffusion member The lighting device according to claim 6, characterized in that: The diffusion member has a plate shape including a first surface opposite to the light emitting surface and a second surface opposite to the first surface.
The lighting device according to any one of claims 1 to 7, wherein at least one of the first surface and the second surface is a rough surface.   The lighting device according to any one of claims 1 to 8, wherein the diffusion member includes particles for scattering light.   The lighting device according to any one of claims 1 to 9, wherein the diffusion member is disposed apart from the light guide.   The lighting device according to any one of claims 1 to 9, wherein the diffusion member is in contact with the light guide.   The illumination device according to any one of claims 1 to 11, wherein the light guide further includes a reflection pattern disposed to face the emission surface. The lighting device further includes a frame that houses the light source and the light guide,
The lighting device according to any one of claims 1 to 12, wherein the diffusion member is supported by the frame. The illumination device according to any one of claims 1 to 13, which illuminates an object to be illuminated.
A condenser for condensing the light of the object to be illuminated;
A line sensor that receives light from the light collector;
The image sensor unit, wherein the diffusion member is disposed on an area of the light guide corresponding to an effective reading area of the line sensor. The illumination device according to any one of claims 1 to 12, which illuminates an object to be illuminated.
A condenser for condensing the light of the object to be illuminated;
A line sensor that receives light from the light collector;
A sensor frame containing the illumination device, the light collector and the line sensor;
The image sensor unit characterized in that the diffusion member is disposed on a region of the light guide corresponding to an effective reading region of the line sensor, and supported by the sensor frame.   The image sensor unit according to claim 14 or 15, wherein a member having a light diffusion degree higher than that of the diffusion member is not disposed between the illumination target and the line sensor.

Images