JP2009193884A - Illuminating device and display using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To increase and equalize the brightness of an illuminating device 1 having a light source 4, a tabular light guide plate 2, and a reflector 3 disposed on the backside of the light guide plate 2. <P>SOLUTION: The light guide plate 2 has a plurality of reflective portions 5 that are recesses formed on the surface or backside of the light guide plate 2 to outwardly emit light from the light source 4. Each of the reflective portions 5 has a curved reflective surface 6 on its side face closer to the light source 4. Each of the recesses has a sectional shape of an approximate right triangle or an approximate isosceles triangle with the base equivalent to a straight line made by the surface or the backside. An angle made between the reflective surface 6 and the base is within a range of 0° to 90° not inclusive of 0° and 90°. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a lighting device having a flat light emitting surface and a display device using the same.

  Liquid crystal display devices are widely used in portable devices such as notebook personal computers, mobile phones, PDAs, and electronic dictionaries. Since the liquid crystal panel used in the liquid crystal display device is not a self-luminous type, it is necessary to incorporate a flat illumination device on the back surface of the liquid crystal panel. Since a lighting device for portable equipment is required to be thin, a thick light-emitting source cannot be used on the back surface of the liquid crystal panel. On the other hand, this type of display device needs to have high illumination light intensity so that it can be seen outdoors during the day. In addition, uniform light emission without uneven brightness is desired for the displayed image. Therefore, a sidelight type illumination device has been studied. In the sidelight type lighting device, the light source can be installed on the side surface of the light emitting surface, so that the entire thickness can be reduced (see, for example, Patent Document 1).

  The structure of such a conventionally known lighting device 50 is schematically shown in FIGS. 8A and 8B are longitudinal sectional views, and FIG. 9 is a plan view. The lighting device 50 includes a light source 53, a light guide plate 51, and a reflection plate 54. The light source 53 is disposed on the side surface of the light guide plate 51, and light emitted from the light source 53 is introduced into the light guide plate 51. On the back surface of the light guide plate 51, a plurality of reflecting portions 52 formed of V-shaped grooves as shown in FIG. 8A or hemispherical depressions as shown in FIG. 8B are formed. . The light confined between the front and back surfaces of the light guide plate 51 is reflected by the reflecting portion 52 and emitted from the front surface of the light guide plate 51. Therefore, the light confined in the light guide plate 51 can be taken out from the surface of the light guide plate 51 by appropriately setting the reflection portion 52. Further, the reflection plate 54 reflects the light leaking from the back surface of the light guide plate 51 toward the light guide plate 51 again, and prevents the intensity of illumination light extracted from the upper surface of the light guide plate 51 from being lowered.

As shown in FIG. 9, a large number of reflecting portions 52 are formed on an arc centered on the light source 53. The reflection portion 52 has a rectangular shape when viewed from above, and the longitudinal direction of the rectangle is formed to be substantially perpendicular to the direction of the light source 53. By arranging the reflection part 52 in this way, the reflected light reflected by the reflection part 52 can be concentrated in the vertical direction of the surface of the light guide plate 51, and for example, when applied to a liquid crystal display device, a bright display is obtained. be able to.
JP-A-11-250714

  With the shape of the conventional reflector 52, it is impossible to obtain the optimal directivity of illumination light when the display panel is illuminated.

  For example, the case where the reflection part 52 is comprised with the V-shaped groove | channel shown to Fig.8 (a) is demonstrated. FIG. 10A is an enlarged cross-sectional view of the reflection part 52 of the V-shaped groove formed on the back surface of the light guide plate 51, and FIG. 10B shows the distribution characteristics of the emitted light at this time. The light reflected by the reflection part 52 of the V-shaped groove is emitted substantially parallel to the perpendicular to the back surface of the light guide plate 51. Therefore, as shown in FIG. 10B, the distribution of the emitted light is concentrated in a very narrow range, and the lighting device has high directivity. Since the range of the emitted light is very narrow, the appearance in front of the lighting device and the appearance from an inclined angle are greatly different. For this reason, it is necessary to impart a diffusion effect to the light guide plate 51 or to dispose a diffusion plate above the light guide plate 51.

  Further, the case where the reflecting portion 52 is configured by the hemispherical depression shown in FIG. FIG. 11A is an enlarged cross-sectional view showing the reflecting portion 52 formed of a hemispherical depression formed on the back surface of the light guide plate 51. FIG. 11B shows the distribution characteristics of the emitted light according to this configuration. . The light reflected by the reflecting part 52 is emitted with a large inclination from the normal to the surface of the light guide plate 51. Therefore, as shown in FIG. 11B, the distribution of the emitted light is dispersed in a very wide range, and the lighting device has a strong diffusivity. Since the emitted light is dispersed, high brightness cannot be obtained in front of the lighting device. Therefore, a prism sheet that corrects the emitted light in the direction perpendicular to the surface of the light guide plate 51 needs to be disposed on the light guide plate 51.

  The present invention has the following configuration in order to solve the above-described problems.

  (1) In an illuminating device including a light source, a flat light guide plate having a front surface and a back surface, and a reflector disposed on the back surface side of the light guide plate, a plurality of reflections are provided on at least one of the front surface or the back surface of the light guide plate. A reflection surface is provided on the light source side surface of the reflection portion, the reflection surface has an intersection line intersecting the front surface or the back surface, and the reflection surface is a curved surface.

  (2) In the illumination device according to (1), the intersecting line is formed of a straight line, and the intersecting line is arranged substantially at right angles to the direction in which the light source is located.

  (3) In the illumination device according to (1) or (2), the cross section cut out by a plane perpendicular to the circumferential direction centering on the light source has a straight line formed by the front surface or the back surface as a base. The angle between the reflecting surface and the base is changed in a range of 30 ° to 60 °.

  (4) A display device was configured by disposing a non-self-luminous display panel on the irradiation surface (light emitting surface) side of the illumination device having any one of the above configurations (1) to (3).

  A lighting device including a light source, a light guide plate, and a reflector, the light guide plate including a plurality of reflecting portions on at least one of a front surface and a back surface, and a reflecting surface on a light source side surface of the reflecting portion. Was a curved surface. Uniform illumination light with high brightness and little brightness unevenness can be emitted to the front of the lighting device. In other words, an illuminating device having both directivity and diffusivity was realized.

  An illuminating device of the present invention is an illuminating device including a light source, a flat light guide plate having a front surface and a back surface, and a reflector installed on the back surface side of the light guide plate, at least on the front surface and the back surface of the light guide plate. A plurality of reflecting portions are formed on one surface, and the reflecting portion is formed of a concave portion, and a side surface of the concave portion on the light source side is a curved reflecting surface. Thereby, since the direction and light quantity of the light reflected by the reflecting surface can be controlled, the directivity and diffusibility of the light emitted to the front surface of the illumination device can be controlled.

  Furthermore, the cross-sectional shape of the concave portion is a substantially right triangle or a substantially isosceles triangle whose bottom is a straight line formed by the front surface or the back surface, and the angle between the reflection surface and the bottom is 0 ° to 90 ° not including 0 ° and 90 °. It is good also as changing in a range. In particular, the curved surface was formed so that the angle between the reflecting surface and the base changed within a range of 30 ° to 60 °. As a result, an illuminating device having both directivity and diffusibility can be realized, and for example, it has characteristics suitable for an illuminating device of a non-self-luminous display element.

  Further, the intersection line between the front or back surface of the light guide plate and the reflection surface is a straight line, and this intersection line is configured to be substantially perpendicular to the direction in which the light source is located.

  In addition, the area of the reflecting surface is configured to increase as the distance between the reflecting portion and the light source increases. Alternatively, the total area of the reflection surface per unit area of the front surface or the back surface is configured to increase as the distance between the reflection portion and the light source increases. Moreover, you may comprise so that the depth of a recessed part may become deep as the distance of a reflection part and a light source increases.

  Further, the length of the reflection surface in the circumferential direction is configured to increase as the distance between the reflection portion and the light source increases. In addition, the reflecting portions are periodically arranged in the radial direction around the light source, and the radial pitch of the reflecting portions is configured to become narrower as the distance between the reflecting portion and the light source increases.

  In addition, a display device of the present invention includes a lighting device having any one of the configurations described above, and a non-self-luminous display panel arranged on the irradiation surface side of the lighting device.

Hereinafter, the present invention will be specifically described with reference to the drawings.
(Example 1)
FIG. 1 is a diagram schematically illustrating a lighting device 1 according to the present embodiment. FIG. 1A is a longitudinal sectional view of the lighting device 1, FIG. 1B is an enlarged sectional view of the reflecting portion 5, and FIG. 1C is a perspective view of the lighting device 1. The same portions or portions having the same function are denoted by the same reference numerals.

  As shown in FIG. 1A, the light guide plate 2 has a flat plate shape having a front surface and a back surface, a reflector 3 is installed on the back surface side, and a light source 4 is installed on the side surface. Light emitted from the light source 4 is introduced into the light guide plate 2.

  The reflection part 5 is composed of a recess formed on the back surface of the light guide plate 2. As shown in FIG. 1B, in this embodiment, the cross-sectional shape of the recess is a substantially isosceles triangle. This cross section is a cross section when the reflecting portion is cut by a plane perpendicular to the back surface of the light guide plate among the planes including the straight line connecting the light source and the central point of the reflecting portion. Here, the inclined surface closer to the side where the light source 4 is located functions as the reflecting surface 6. A line connecting the intersecting line 10 where the reflecting surface 6 and the back surface of the light guide plate 2 intersect with the vertex 11 of the reflecting portion 5 is not a straight line indicated by a dotted line in the drawing but a curve bulging toward the light source 4 side. That is, the reflecting surface 6 is a curved surface. The effect of the reflection part 5 is demonstrated using FIG.1 (b). The light A1 emitted from the light source 4 is reflected by the reflecting surface 6 and is emitted inclined from the perpendicular to the surface of the light guide plate 2 to the side opposite to the direction in which the light source 4 is located. The light A2 emitted from the light source 4 is reflected by the reflecting surface 6 and is emitted in the direction perpendicular to the surface of the light guide plate 2. The light A3 emitted from the light source 4 is reflected by the reflecting surface 6 and is emitted inclined from the normal to the surface of the light guide plate 2 in the direction in which the light source 4 is located.

  2A is a plan view of the illuminating device 1, and FIG. 2B is a front view of the illuminating device 1 viewed from the light source 4 side. A light beam B <b> 1 reflected by the reflecting portion 5 in which the intersecting line 10 is arranged at a substantially right angle with respect to the light source 4 is emitted in parallel to the perpendicular to the surface of the light guide plate 2. However, the light beam B <b> 2 reflected by the reflecting portion 5 in which the intersecting line 10 is not arranged at a substantially right angle with respect to the light source 4 is emitted with a large inclination from the normal to the surface of the light guide plate 2. As described above, the intersecting line 10 of the reflecting portion 5 is arranged at a substantially right angle with respect to the light source 4, thereby increasing the luminance emitted from the surface of the light guide plate 2.

FIG. 3 is an enlarged cross-sectional view of the reflecting portion 5. 3 (a) and 3 (b) show a conventional reflecting portion 5, and FIG. 3 (c) shows the reflecting portion 5 of the present invention. The conventional reflecting section 5 shown in FIG. 3A has a flat reflecting surface 6, and the angles θ1 to θ3 formed by the reflecting surface 6 and the back surface of the light guide plate 2 are constant. Therefore, the light emitted from the light source 4 is reflected by the reflecting portion 5 in the direction of the perpendicular to the light guide plate surface. The conventional reflecting portion 5 shown in FIG. 3B is hemispherical, and the entire hemispherical surface is the reflecting surface 6. The angles θ1 to θ3 formed by the reflective surface 6 and the back surface of the light guide plate 2 vary from 0 ° to 90 °. Therefore, the light emitted from the light source 4 is reflected by the reflecting portion 5 in a direction greatly inclined from the normal to the surface of the light guide plate. FIG.3 (c) is the reflection part 5 of this invention, and the reflective surface 6 is comprised by the curved surface. The cross section of the concave portion is a substantially right triangle or a substantially isosceles triangle whose bottom is the straight line formed by the back surface of the light guide plate, and the angle formed by the reflecting surface and the bottom varies in the range of 30 ° to 60 °. That is, θ1 to θ3 in FIG. 3C satisfy the equation 30 ° ≦ θ ≦ 60 °. With such a configuration, the light emitted from the light source 4 is reflected by the reflecting portion 5 and is emitted in a direction parallel to the normal to the surface of the light guide plate 2 and one emitted in a direction inclined from the normal. To be separated. As a result, the luminance emitted from the surface of the light guide plate 2 increases, the controllability of the luminance distribution improves, and it becomes easy to design uniform illumination light. Moreover, the appearance in the front of the illuminating device 1 and the appearance from the inclined angle are the same.
(Example 2)
FIG. 4A shows a longitudinal sectional view of the illumination device 1 of this embodiment. The same portions or portions having the same functions are denoted by the same reference numerals as those in the above-described embodiment, and redundant description is omitted. The reflection portion 5 is a recess formed on the back surface of the light guide plate 2, and the side surface of the reflection portion 5 on the light source 4 side is the reflection surface 6. The depth H from the back surface of the light guide plate 2 of the reflecting portion 5 increases as the distance from the light source 4 increases. Thereby, control of the illumination light radiate | emitted from the surface of the light-guide plate 2 becomes easy, and uniform brightness | luminance can be obtained.
(Example 3)
FIG. 4B shows a longitudinal sectional view of the lighting device 1 of this embodiment. The same portions or portions having the same functions are denoted by the same reference numerals as those in the above-described embodiment, and redundant description is omitted. The reflection portion 5 is a recess formed on the back surface of the light guide plate 2, and the side surface of the reflection portion 5 on the light source 4 side is the reflection surface 6. The distance P between the reflecting portion 5 and another adjacent reflecting portion 5 becomes shorter as the distance from the light source 4 increases. Thereby, control of the illumination light radiate | emitted from the surface of the light-guide plate 2 becomes easy, and uniform brightness | luminance can be obtained.
Example 4
FIG.4 (c) is a top view of the illuminating device 1 which concerns on a present Example. The same parts and parts having the same function are denoted by the same reference numerals. The reflection portion 5 is a recess formed on the back surface of the light guide plate 2, and the side surface of the reflection portion 5 on the light source 4 side is the reflection surface 6. An intersection line 10 where the reflecting portion 5 and the back surface of the light guide plate 2 intersect becomes longer as the distance from the light source 4 increases. Thereby, control of the illumination light radiate | emitted from the surface of the light-guide plate 2 becomes easy, and uniform brightness | luminance can be obtained. The other configuration is the same as that of the first embodiment, and is omitted.

  FIG. 6 is an enlarged perspective view showing the reflecting portion 5. In each of the above-described embodiments, the reflecting portion 5 is a concave portion that looks rectangular when viewed from the light source 4 as shown in FIG. 6A. However, the present invention is not limited to this, and FIG. A concave portion that looks like a trapezoid when viewed from the light source 4 as shown, or a concave portion that looks like a triangle when viewed from the light source 4 as shown in FIG. Further, other shapes may be used.

  In each embodiment described above, an LED can be used as the light source 4. Examples of the material of the light guide plate 2 include translucent plastic materials such as acrylic (PMMA), polycarbonate (PC), and cycloolefin polymer (COP), and glass. The reflection portion 5 may be formed on the front surface of the light guide plate 2 instead of the back surface, or may be formed on both the front and back surfaces of the light guide plate 2. In short, it is only necessary to have a reflection structure that can reflect light in a direction perpendicular to the surface of the light guide plate 2. The reflector 3 may be a plate-like reflector or a film-like reflector sheet. The reflector 3 may be a reflective film in which a metal film of Ag or Al is deposited on the back surface of the light guide plate 2.

(Example 5)
FIG. 7 is a schematic longitudinal sectional view of the liquid crystal display device 20 of the present embodiment using a liquid crystal display panel as a non-self-luminous display element. The same portions or portions having the same function are denoted by the same reference numerals. As illustrated, the liquid crystal display device 20 has a configuration in which a liquid crystal display panel 15 is disposed on the irradiation surface side of the illumination device 1. The liquid crystal display panel 15 includes a liquid crystal panel 17 in which two glass substrates are bonded to each other with a gap provided by a sealing material, and a liquid crystal layer (not shown) is provided in the gap, and an upper polarizing plate 16 that is bonded to the outer surface. And a lower polarizing plate 18. The illuminating device 1 is composed of a light guide plate 2, a light source 4 installed on the side surface thereof, and a reflector 3 installed on the back surface thereof, and has any of the configurations of the illuminating devices already described above. A light diffusing plate may be provided between the lighting device 1 and the liquid crystal display panel 15. Furthermore, a prism sheet may be inserted between the light diffusion plate and the liquid crystal display panel 15 as necessary.

It is explanatory drawing for demonstrating the illuminating device which concerns on the Example of this invention. It is explanatory drawing for demonstrating the illuminating device which concerns on the Example of this invention. It is an expanded sectional view of the reflection part which comprises the illuminating device which concerns on the Example of this invention. It is explanatory drawing for demonstrating the illuminating device which concerns on the Example of this invention. It is an expanded sectional view of the reflection part which comprises the illuminating device which concerns on the Example of this invention. It is an expanded sectional view of the reflection part which comprises the illuminating device which concerns on the Example of this invention. . It is typical sectional drawing of the liquid crystal display device based on the Example of this invention. It is a typical longitudinal cross-sectional view of a conventionally well-known illuminating device. It is a typical top view of a conventionally well-known illumination device. It is an expanded sectional view of the reflection part which comprises a conventionally well-known illumination device. It is an expanded sectional view of the reflection part which comprises a conventionally well-known illumination device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Light guide plate 3 Reflector 4 Light source 5 Reflecting part 6 Reflecting surface 10 Intersecting line 11 Vertex 15 Liquid crystal display panel 16 Upper polarizing plate 17 Liquid crystal panel 18 Lower polarizing plate 19 Light diffusing plate 20 Liquid crystal display device 50 Illuminating device 51 Guide Optical plate 52 Reflector 53 Light source 54 Reflector

Claims (10)

In a lighting device comprising a light source, a flat light guide plate having a front surface and a back surface, and a reflector installed on the back surface side of the light guide plate,
While comprising a plurality of reflective portions formed on at least one of the front and back surfaces of the light guide plate,
The illuminating device characterized in that the reflecting portion is formed of a concave portion, and a side surface of the concave portion on the light source side is a curved reflecting surface.   The cross-sectional shape of the concave portion is a substantially right triangle or a substantially isosceles triangle whose bottom is a straight line formed by the front surface or the back surface, and the angle between the reflection surface and the bottom is 0 ° not including 0 ° and 90 °. It changes in the range of -90 degrees, The illuminating device of Claim 1 characterized by the above-mentioned.   The lighting device according to claim 2, wherein an angle between the reflecting surface and the base changes in a range of 30 ° to 60 °.   The intersection surface where the reflection surface intersects the front surface or the back surface is a straight line, and the reflection surface is arranged so that the intersection line is substantially perpendicular to the direction in which the light source is located. Item 4. The lighting device according to any one of Items 1 to 3.   5. The lighting device according to claim 1, wherein an area of the reflection surface increases as a distance between the reflection portion and the light source increases.   5. The total area of the reflection surface per unit area of the front surface or the back surface increases as the distance between the reflection portion and the light source increases. 6. Lighting equipment.   The lighting device according to claim 5 or 6, wherein the depth of the concave portion becomes deeper as the distance increases.   The lighting device according to claim 5, wherein a length of the reflecting surface in a circumferential direction becomes longer as the distance increases. The reflecting portion is periodically arranged in the radial direction around the light source,
The lighting device according to any one of claims 5 to 8, wherein the pitch in the radial direction of the reflecting portion becomes narrower as a distance between the reflecting portion and the light source increases.   A display device comprising: the illumination device having the configuration according to any one of claims 1 to 9; and a non-self-luminous display panel disposed on an irradiation surface side of the illumination device.

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