JP2011003437A - Reflective structural body, light scattering member, light guide plate, and illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable light to reach the side end part in a reflective structural body or a light guide plate.SOLUTION: The reflective structural body includes a first face (11) having two side end parts (11a, 11b) which are mutually opposing and a plurality of light scattering bodies (21) to scatter light. Regarding a perpendicular cross-section to an axis (11c) positioned on the first face between two side end parts, a height (h) from the first face of individual light scattering bodies becomes smaller as going from the axis toward the side end parts.

Description

  The present invention relates to a reflective structure, a light scattering member, a light guide plate, and a lighting device.

  As a prior art, a light guide plate for a backlight of a liquid crystal display device having a hemispherical scatterer on at least one surface is disclosed.

JP 2005-249882 A

  However, since the hemispherical scatterers (or reflectors) are arranged so as to have a constant height, the light incident from the center of the light guide plate and reflected by the center scatterer is reflected on the light guide plate. It is difficult to reach the side edge.

  In view of such a problem, an object of the present invention is to allow light to reach a side end portion of a reflective structure or a light guide plate.

  A reflective structure according to an aspect of the present invention includes a first surface having two side end portions facing each other, and a plurality of light scatterers that are formed on the first surface and scatter light. With respect to the cross section perpendicular to the axis located on the first surface between the two side ends, the height of the individual light scatterers from the first surface is from the axis toward the side end. It is characterized by becoming smaller.

  According to the present invention, the amount of light reaching each light scatterer up to the side end increases, and the light emission efficiency of the reflective structure or the light guide plate increases.

It is a schematic perspective view of a light-guide plate. (A) It is a bottom view which shows the 1st surface of a light-guide plate. (B) It is an end elevation which shows the 2nd surface of a light-guide plate. (C) It is a front view which shows the 3rd surface of a light-guide plate. (D) It is a rear view which shows the 4th surface of a light-guide plate. (E) It is a side view which shows the 5th surface or 6th surface of a light-guide plate. (F) It is a perspective view which shows the other example of the shape of a 2nd surface. (A) It is a figure which illustrates partially the reflective structure of a 1st surface. (B) It is sectional drawing which shows the change of the height of the light-scattering body in a reflective structure. (C) It is sectional drawing which shows the form of the side surface of a light-scattering body. (D) It is sectional drawing which shows the other form of the side surface of a light-scattering body. (A) It is a perspective view which shows the light-scattering body of a quadrangular pyramid shape. (B) It is a perspective view which shows a hemispherical-shaped light-scattering body. (C) It is a perspective view which shows the light-scattering body of a semi-ellipsoid shape. (A) It is sectional drawing which shows the change of the height of a light-scattering body, when a light-scattering body is hemispherical shape. (B) It is sectional drawing which shows the change of the height of a light-scattering body, when a light-scattering body is a semi-ellipsoid shape. It is sectional drawing which shows the condition where the ratio of the height and radius of a light-scattering body changes when a light-scattering body is a part of spherical shape. (A) It is a figure which shows an example of the diffraction grating pattern of the 3rd surface. (B) It is a figure which shows the other example of the diffraction grating pattern of a 3rd surface. (C) It is a figure which shows the light which passes the diffraction grating of a 3rd surface. (A) It is a figure which shows an example of the diffraction grating pattern of a 4th surface. (B) It is a figure which shows the other example of the diffraction grating pattern of a 4th surface. (C) It is a figure which shows the light from the diffraction grating of a 4th surface. (A) It is a figure which shows an example of distribution of the light-scattering body of a 1st surface. (B) It is a figure which shows another example of distribution of the light-scattering body of a 1st surface. (C) It is a figure which shows another example of distribution of the light-scattering body of a 1st surface. (A) It is a figure which shows an example of a structure of an illuminating device. (B) It is a figure which shows the other example of a structure of an illuminating device.

[First embodiment]
With reference to FIG. 1, the light-guide plate which concerns on 1st embodiment is demonstrated. The light guide plate is used as an illumination device for an endoscope, but is not limited to this.

  Light from the light source is introduced into the light guide plate 1 through a light guide 3 such as an optical fiber bundle. The light guide plate 1, the light guide 3, and the light source constitute an illumination device. The light guide plate 1 may be made of a transparent member, for example, a transparent resin material or a translucent resin material, and may be a polycarbonate material or an acrylic resin. The material of the light guide plate 1 may be glass.

  The light guide plate 1 has a first surface 11, a second surface 12, a third surface 13, a fourth surface 14, a fifth surface 15, and a sixth surface 16 as shown in FIGS. . The first surface 11 and the second surface 12 face each other, the third surface 13 and the fourth surface 14 face each other, and the fifth surface 15 and the sixth surface 16 face each other. The third surface 13, the fourth surface 14, the fifth surface 15, and the sixth surface 16 are located between the first surface 11 and the second surface 12.

  A plurality of light scatterers 21 that scatter light introduced into the light guide plate 1 are formed on the first surface 11 (FIG. 2A) of the light guide plate 1. The plurality of light scatterers 21 on the first surface 11 constitute a reflective structure. Thereby, the incident light incident on the light guide plate 1 can be scattered by the first surface 11, and light can be emitted in a wide range from the second surface 12 facing the first surface 11 into the air. For example, as shown in FIG. 2A, the plurality of light scatterers 21 are arranged in a square lattice pattern with a substantially uniform density.

  The second surface 12 (FIG. 2B) is a transmission surface that transmits light. The second surface 12 is a semi-cylindrical (cylinder-shaped) curved surface. For this reason, it is prevented that the light which goes to a 2nd surface at a big angle so that a wide range is illuminated is totally reflected by a 2nd surface. The semi-cylindrical curved surface is a curved surface portion obtained by cutting a cylinder along a plane parallel to its rotational symmetry axis. As shown in FIG. 2 (f), the second surface 12 can be simply formed into a roof shape.

  The exit end surface of the light guide 3 is located in the third surface 13 (FIG. 2C). In the third surface 13, at least a part corresponding to the exit end surface of the light guide 3 is a transmission surface 13 a that transmits light. In FIG. 1, the transmission surface 13 a is located on the first surface 11 side in the vicinity of the central portion in the longitudinal direction of the third surface 13, but is not limited thereto. The light guide 3 constitutes a light incident means (light incident portion) disposed to face the transmission surface 13 a of the third surface 13.

  The fourth surface 14 (FIG. 2D) has the same shape as the third surface 13, but in the fourth surface 14, the separation distance (height) between the first surface 11 and the second surface 12 is It is smaller than the third surface 13.

  The fourth surface 14, the fifth surface 15, and the sixth surface 16 are all reflective surfaces. The fourth surface 14, the fifth surface 15, and the sixth surface 16 extend from the three sides that define the first surface 11 to the same side with respect to the first surface 11. By surrounding the light guide plate 1 with the reflection surface in this way, light can be emitted from a desired direction (second surface 12). Moreover, the light emission efficiency of the light inject | emitted from the 2nd surface 12 improves because the surface except the 3rd surface 13 (light incident part) and the 2nd surface 12 is a reflective surface. The luminous efficiency is a ratio between the amount of light entering the light guide plate 1 per unit time and the amount of light exiting the light guide plate 1 per unit time.

  Further, since the fifth surface 15 (sixth surface 16) has the shape as shown in FIG. 2E, the separation distance between the first surface 11 and the second surface 12 is changed from the third surface 13 to the fourth surface. It becomes small as it goes to 14. This is a countermeasure against the incident light becoming difficult to reach as the distance from the third surface 13 increases. Thereby, the first surface 11 is inclined with respect to the optical axis 3a of the incident light, and the probability that the incident light collides with the reflecting structure of the first surface 11 also in the vicinity of the fourth surface 14 is improved, and the light emission efficiency is increased. .

  Next, with reference to FIG. 3 (a) (b), the structure of the reflective structure of the 1st surface 11 is demonstrated in detail.

  The light scatterer 21 of the reflective structure has a refractive index different from that of the transparent or transmissive material of the light guide plate 1 and scatters or reflects light. The light scatterer 21 may be a dent (or groove) formed in the first surface 11 and can scatter light because the material of the light guide plate 1 and the refractive index of air in the dent are different. In addition, if the material of the light-guide plate 1 is a resin material, it will become easy to form the some light-scattering body 21 as a dent. Alternatively, the light scatterer 21 is a material having a refractive index different from that of the light guide plate 1 and may be embedded in the first surface 11.

  Although the light scatterer 21 can take various shapes, in this embodiment, the case where the light scatterer 21 has a substantially conical shape as shown in FIG. For example, the bottom 21a (in the first surface) of each light scatterer 21 has a circular shape with substantially the same diameter, but is not limited thereto. The portion of the first surface 11 other than the light scatterer 21 is preferably a reflective surface.

  The first surface 11 has two side end portions 11a and 11b facing each other. The shaft 11c is set so as to be positioned in the central portion between the two side end portions 11a and 11b in the first surface 11 or in the vicinity thereof. The shaft 11c may be substantially parallel to the side end portions 11a and 11b. As shown in FIG. 3B, the height h from the first surface 11 of the light scatterer 21 gradually decreases from the shaft 11c toward the one side end portion 11a in the cross section perpendicular to the shaft 11c. At the same time, it gradually decreases from the shaft 11c toward the other side end 11b. Thereby, a high light scatterer is arrange | positioned in the center vicinity of the light-guide plate 1, and a light scatterer becomes low as it approaches the side edge parts 11a and 11b. Light scattered by the central high light scatterer easily reaches the side edge. Therefore, the amount of light reaching each light scatterer up to the side end portion increases, and the light emission efficiency of the light guide plate 1 increases.

  In addition, the axis 11c can be set to be obtained by projecting the optical axis 3a of incident light incident on the light guide plate 1 from the light guide 3 perpendicularly to the first surface 11. Thereby, the diffusion effect by the light scatterer in the vicinity of the optical axis of the incident light is improved, and the amount of light reaching the side end portion is increased. Further, the transmission surface 13a of the third surface is located in the vicinity of the intersection between the shaft 11c and the third surface 13. Since the light scatterer 21 is large, the light can be effectively scattered by making the light incident near the axis 11c where the diffusion effect is large. Note that when light is incident from the transmission surface 13a at a position slightly deviated toward one side end with respect to the shaft 11c, the light emission ratio in the deviated direction increases.

  As shown in FIG. 3C, regarding the cross section perpendicular to the axis 11 c, the axial side point 21 c of the contact points between the side surface 21 b of each light scatterer 21 and the first surface 11, the side surface 21 b of the light scatterer 21. An angle θ1 formed between the tangent line and the first surface 11 is set. In this case, the angle θ1 may gradually decrease from the shaft 11c toward the side end portions 11a and 11b. Thus, the normal direction of the side surface 21b of the light scatterer 21 is gradually changed as the distance from the axis 11c increases. For this reason, the reflection (scattering) directions of light from the plurality of light scatterers 21 are varied, and the light emission angle from the second surface 12 that is the emission surface can be widened.

  Note that the angle θ1 may be constant as shown in FIG. In this case, the individual light scatterers 21 can be manufactured with the same shape, and the processing becomes easy. For example, the light scatterer 21 can be manufactured by easy processing as a recess of the same type in a resin material.

  As the shape of the other light scatterers 21, as shown in FIGS. 4A to 4C, a quadrangular pyramid, a hemisphere, and a semi-ellipsoid may be used. FIGS. 5A and 5B illustrate changes in height when the shape of the light scatterer 21 is a hemisphere or a semi-ellipsoid. Within the cross section perpendicular to the axis 11c, the height h from the first surface 11 of the light scatterer 21 gradually decreases from the axis 11c toward the side end portions 11a and 11b. In FIG. 5A, the radius of the hemisphere gradually decreases from the axis 11c toward the side end portions 11a and 11b, but the ratio h / height between the height h from the first surface 11 and the spherical radius r. r is 1 and constant. Here, the angle θ formed by the normal direction of the side surface 21b of each light scatterer 21 and the normal direction of the first surface 11 changes continuously.

-Effect-
Incident light incident on the light guide plate 1 can be scattered by the reflecting structure formed on the first surface 11, and light can be emitted in a wide range from the second surface 12 facing the first surface 11 into the air. The height of the light scatterer 21 from the first surface 11 decreases from the axis 11c toward the side end portions 11a and 11b. For this reason, the amount of light reaching each light scatterer up to the side end increases, and the light emission efficiency of the light guide plate increases. Actually, according to the simulation, it can be confirmed that the luminous efficiency is improved by several percent as compared with the prior art. The angle θ1 formed between the tangent to the light scatterer and the first surface 11 may be reduced from the axis 11c toward the side end portions 11a and 11b. In this case, the light emission angle from the second surface 12 (exit surface) can be widened.

  The fourth surface 14, the fifth surface 15, and the sixth surface 16 may all be reflective surfaces. In this case, light can be emitted from the second surface 12 which is a transmission surface. The separation distance between the first surface 11 and the second surface 12 may decrease as the distance from the third surface 13 toward the fourth surface 14 increases. In this case, the first surface 11 is inclined with respect to the optical axis 3 a of the incident light, and the incident light collides with the reflecting structure on the first surface 11 up to the vicinity of the fourth surface 14. The second surface 12 may be a semi-cylindrical curved surface. In this case, light traveling toward the second surface 12 at a large angle so as to illuminate a wide range can be prevented from being totally reflected by the second surface 12. The axis 11 c may correspond to a projection of the optical axis 3 a of light incident from the transmission surface of the third surface 13 perpendicularly to the first surface 11. In this case, the light diffusion effect in the vicinity of the optical axis of the incident light is improved, and the amount of light reaching the side end portion is increased.

[Second Embodiment]
The second embodiment shows a case where the shape of the light scatterer is a part of a sphere (radius r). Other configurations are the same as those in the first embodiment. In FIG. 6, θ <b> 2 is an angle formed by the normal direction at the contact point 21 c between the side surface 21 b of the light scatterer 21 and the first surface 11 and the normal direction of the first surface 11.

  As shown in FIG. 6, the ratio h / r between the height h of the light scatterer from the first surface 11 and the radius r of the sphere is within the cross section perpendicular to the axis 11c, and the side edges 11a and 11b from the axis 11c. It becomes smaller gradually toward. The angle θ formed by the normal direction of the side surface 21b of each light scatterer 21 and the normal direction of the first surface 11 changes continuously within a range from the angle −θ2 to the angle θ2.

  Thus, by arranging the light scatterer 21 having a spherical surface as the side surface 21b, the reflective structure scatters light over a wide range without directivity in the reflection direction. Further, as the value of h / r gradually decreases, the angle θ gradually decreases from the axis 11c toward the side end portions 11a and 11b, and light is scattered over a wide range.

  In the present embodiment, the spherical radius r is the same value in all the light scatterers 21, and only the height h changes. However, the present invention is not limited to this, and the radius r may also be changed. In addition, when the spherical radius r takes the same value in all the light scatterers 21, the formation (machining or the like) of the plurality of light scatterers 21 is facilitated by taking a uniform spherical shape.

  Similarly to the first embodiment, the height h from the first surface 11 of the light scatterer 21 gradually increases from one shaft 11c toward one side end portion 11a in a cross section perpendicular to the shaft 11c. And gradually decreases from the shaft 11c toward the other side end 11b.

-Effect-
By gradually reducing the value of h / r, the angle in the normal direction of the side surface 21b of the light scatterer 21 gradually decreases from the axis 11c toward the side end portions 11a and 11b, and light is scattered over a wide range. Is done. When the spherical radius r of the light scatterer 21 has the same value in all the light scatterers 21, formation of a plurality of light scatterers 21 (machining or the like) is facilitated.

[Third embodiment]
In the third embodiment, a diffraction grating is formed on the third surface 13 and / or the fourth surface 14. Other configurations are the same as those in the first embodiment.

  7A and 7B show a pattern (grating pattern) of the diffraction grating 31 on the third surface 13. FIG. 7A shows a concentric grating pattern. FIG. 7B shows a parallel linear grating pattern. These grating patterns collect light toward the first surface 11 as shown in FIG.

  In the grating pattern shown in FIG. 7A, light can be condensed near the axis 11c of the first surface 11, and light easily collides with the light scatterer 21 on the first surface 11 to increase the light emission efficiency. This is because the height h of the light scatterer 21 is high in the vicinity of the axis 11 c of the first surface 11. Further, since the light is collected near the axis 11c of the first surface 11, the light is incident on the axis 11c at an angle. Thereafter, the light is reflected obliquely with respect to the axis 11c. That is, the light incident from the third surface is incident on the first surface 11 and reflected from the first surface 11 in a direction crossing the axis 11c, so that the light is scattered over a wide range. On the other hand, the grating pattern in FIG. 7B is easier to form than the grating pattern in FIG.

  8A and 8B show patterns (grating patterns) of the diffraction grating 33 on the fourth surface 14. FIG. 8A shows a concentric grating pattern. FIG. 8B shows a parallel linear grating pattern. Since these grating patterns direct light toward the second surface 12 as shown in FIG. 8C, the luminous efficiency is improved.

  In the grating pattern of FIG. 8A, light can be greatly diverged toward the second surface 12. On the other hand, the grating pattern in FIG. 8B is easier to form than the grating pattern in FIG.

  In the third embodiment, it is preferable that the light source generates at least one kind of monochromatic light so that the light is easily diffracted.

-Effect-
Since the diffraction grating 31 is formed on the third surface 13 and the pattern of the diffraction grating 31 is a pattern for condensing light toward the first surface 11, the light emission efficiency of the light guide plate 1 is improved. Since the diffraction grating 33 is formed on the fourth surface 14 and the pattern of the diffraction grating 33 is a pattern that diverges light toward the second surface 12, the light emission efficiency of the light guide plate 1 is improved.

[Fourth embodiment]
In the fourth embodiment, the distribution of the plurality of light scatterers 21 on the first surface is changed from the first embodiment. Other configurations are the same as those in the first embodiment. In the first embodiment, as shown in FIG. 2A, a plurality of light scatterers 21 are arranged in a square lattice pattern with a substantially uniform density.

  In the fourth embodiment, as shown in FIG. 9A, the plurality of light scatterers 21 may be arranged in a triangular lattice pattern by alternately shifting the rows of the light scatterers 21. As shown in FIG. 9B, the distance between the light scatterers 21 (and hence the density of the light scatterers 21) may be gradually reduced from the axis 11c toward the side end portions 11a and 11b. As shown in FIG. 9C, the distance between the light scatterers 21 (and hence the density of the light scatterers 21) may be reduced from the third surface 13 toward the fourth surface 14 in the direction of the axis 11c. .

-Effect-
In 4th embodiment, the effect similar to 1st embodiment is acquired with various reflective structures.

[Fifth embodiment]
In the fifth embodiment, a lighting device 5 is configured by combining a plurality of light guide plates 1. Other configurations are the same as those in the first embodiment.

  As shown in FIG. 10A, in the illuminating device 5, the plurality of light guide plates 1 are arranged substantially symmetrically about the axis 41 around the predetermined axis 41. The first surfaces 11 of the individual light guide plates 1 are all arranged along the axis 41 in parallel therewith. By combining a plurality of light guide plates 1, the lighting device can uniformly illuminate a wide range. For example, the number of the light guide plates 1 is four, but is not limited thereto.

  As shown in FIG. 10B, the plurality of light guide plates 1 may be arranged asymmetrically with respect to the predetermined axis 41. In this case, in some of the light guide plates, the third transmission surface 13a (that is, the exit end surface of the light guide 3) is shifted to one side end side with respect to the shaft 11c to move in the shifted direction. Increase the light emission rate. Thereby, when the gap between the light guide plates is wide, the amount of light emitted toward the side where the gap between the light guide plates is wide can be adjusted.

-Effect-
The illuminating device includes at least two light guide plates, light is incident on each light guide plate, and the first surface of each light guide plate is arranged along a predetermined axis. For this reason, a wide range of angles around the predetermined axis can be irradiated.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

1 Light guide plate 3 Light guide (light incident means)
5 Illuminating device 11 First surface 11a, 11b Side end 11c Axis 12 Second surface 13 Third surface 13a Transmission surface 14 Fourth surface 15 Fifth surface 16 Sixth surface 21 Light scatterer 21a Bottom 21b Side surfaces 31, 33 Diffraction Lattice 41 axis

Claims (14)

A first surface having two side edges facing each other;
A plurality of light scatterers formed on the first surface and scattering light,
With respect to the cross section perpendicular to the axis located on the first surface between the two side ends, the height of the individual light scatterers from the first surface is from the axis toward the side end. A reflective structure characterized in that it becomes smaller.   Regarding the cross section perpendicular to the axis, the angle formed between the tangent of the light scatterer and the first surface at a point on the axis side among the contact points of the side surfaces of the individual light scatterers and the first surface is The reflecting structure according to claim 1, wherein the reflecting structure decreases from an axis toward the side end. The shape of the light scatterer is a partial shape of a sphere,
The reflection structure according to claim 1 or 2, wherein when the radius of the sphere is r and the height is h, the value of h / r decreases from the axis toward the side end. .   The reflection structure according to claim 3, wherein the spherical radius r is the same value in all the light scatterers. The reflective structure according to any one of claims 1 to 4,
And at least three surfaces extending on the same side with respect to the first surface from at least three sides defining the first surface, and the three surfaces are all reflective surfaces. Scattering member.   A light guide plate having translucency, comprising the reflection structure according to any one of claims 1 to 4 on one surface constituting the light guide plate. The reflective structure according to any one of claims 1 to 4, having the first surface;
A second surface that is a transmissive surface that transmits light and faces the first surface;
A third surface located between the first surface and the second surface, including a transmission surface that transmits light;
A fourth surface facing the third surface and positioned between the first surface and the second surface;
A fifth surface including one of the side ends;
A sixth surface including the other of the side end portions and facing the fifth surface,
The light guide plate according to claim 6, wherein the fourth surface, the fifth surface, and the sixth surface are all reflective surfaces. A diffraction grating is formed on the fourth surface;
The light guide plate according to claim 7, wherein the pattern of the diffraction grating is a pattern that diverges light toward the second surface.   9. The light guide plate according to claim 7, wherein a separation distance between the first surface and the second surface decreases from the third surface toward the fourth surface. 10.   The light guide plate according to any one of claims 7 to 9, wherein the second surface is a semi-cylindrical curved surface. A diffraction grating is formed on the third surface;
The light guide plate according to claim 7, wherein the pattern of the diffraction grating is a pattern for condensing light toward the first surface.   The said axis | shaft corresponds to what projected the optical axis of the light which injects from the transmission surface of said 3rd surface perpendicularly | vertically to said 1st surface. Light guide plate. Comprising at least two of the light guide plates according to any one of claims 6 to 11,
Light is incident on each light guide plate, and the first surface of each light guide plate is arranged along a predetermined axis. The light guide plate according to any one of claims 7 to 12,
A light incident means disposed opposite to the transmission surface of the third surface.

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