JP2007194119A - Surface light-emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface light-emitting device to supplement shortage of an amount of light in the center portion of a light guide plate. <P>SOLUTION: The surface light-emitting device comprises a light guide plate which is made of a transparent plate material of nearly flat plate shape and is formed to have an inclined face at the end portion inclined aslant to the main face to become a light emitting face and a light irradiation part which is arranged so as to overlap at least partially with the inclined face when viewed from the light emitting face side of the light guide plate and emits light to the inclined face. Since the inclined face is formed at the end portion, reflection of light to the inner face direction of the light guide plate can be made and the center portion can be made bright even in the light guide plate for a large screen. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a surface light emitting device that emits planar light, and more particularly to a surface light emitting device that outputs a light source in which a plurality of light emitting elements are arranged in a straight line as planar light.

  Recently, as a light source for a backlight of a liquid crystal display device, a light emitting diode element (LED) or a cold cathode tube is used to generate light, and light from the light emitting diode element or the cold cathode tube is emitted in a planar shape. The device is used. In such a surface light-emitting device, light-emitting diode elements and the like are usually arranged on one side surface of the light guide plate, and the light incident from the side surface is reflected by one main surface of the light guide plate and faces the opposite side. Ejected from the main surface. A plurality of dots for reflection are formed on one main surface of the light guide plate that performs reflection, and light incident from the side surface is reflected by the plurality of dots to the exit surface.

  As a light guide plate on which such dots for reflection are formed, the dots are arranged so that a band-like area defined as an area having a certain distribution density is formed, and the interval formed by the dots in each band-like area is set. A technique is known in which generation of bright lines is suppressed by setting the area different from the adjacent band-like areas (see, for example, Patent Document 1). As a light diffusing dot pattern on the reflection surface of the light guide plate, a technique is also known in which the area of the dots is sequentially enlarged as the distance from the light source increases, and the area for light diffusion in a region further away from the light source is increased. (For example, refer to Patent Document 2). Further, there is also known a configuration in which a light guide plate itself having a slope is used so that light incident from the side surface can be reflected at a dispersed position on the exit surface and the entrance surface (see, for example, Patent Document 3). .) In addition, there is also known a technique of forming a V-shaped groove that is thin at the central portion to solve the problem that light does not reach the central portion (see, for example, Patent Document 4).

JP 2003-43266 A JP-A-8-271893 JP-A-6-314069 JP 2001-228477 A

  In general, by using a light guide plate, it is possible to guide light stably, and when a component is assembled, the light guide plate is present at the center of a portion applied to the assembly. They can be aligned and the assembly accuracy can be increased. However, when the surface light emitting device is used for a relatively large signboard, it is necessary to shine the entire large signboard. Therefore, a light guide plate having a large size is indispensable. However, when a relatively large light guide plate is adopted, it is easy to obtain the light intensity at the end of the light guide plate that is close to the light source, but the light at the center of the light guide plate that is far from the light source. Strength will fall. For this reason, in the conventional technique, it has been difficult to obtain luminance of surface light emission with a relatively large area and uniform center and end portions. In addition, the large-sized light guide plate tends to increase the price of the transparent resin material, which tends to increase the overall cost.

  SUMMARY OF THE INVENTION The present invention solves various problems of a surface light-emitting device using a light guide plate in the prior art, and particularly provides a surface light-emitting device that compensates for a lack of light quantity at the center of the light guide plate. .

  In order to solve the above technical problem, the surface light-emitting device of the present invention is made of a substantially flat transparent plate material, and has an inclined surface inclined at an angle with respect to the main surface serving as a light emitting surface. And a light irradiating unit arranged to overlap at least a part of the inclined surface when viewed from the light emitting surface side of the light guide plate and emitting light to the inclined surface. It is characterized by having.

  In a preferred embodiment of the surface light emitting device of the present invention, the light irradiating section may have a structure in which a plurality of light emitting diode elements are arranged in a substantially straight line, and is the main light emitting surface. The inclination angle of the inclined surface with respect to the surface can be set to, for example, an angle of 30 to 60 degrees, more preferably an angle of 40 to 50 degrees, and further, the light guide plate according to the refractive index of the material forming the light guide plate When viewed from the light exit surface side, the light directly transmitted from the light irradiator to the light exit surface side of the light guide plate is suppressed, and most of the light output from the light irradiator is inclined and the light guide plate Any angle may be used so long as it is directed in the in-plane direction.

  In order to solve the above technical problem, another surface light emitting device of the present invention has a plurality of substantially rectangular light guide plates made of a transparent plate and arranged side by side in a flat plate shape, and an end of the light guide plate. An inclined surface that is inclined obliquely with respect to a main surface serving as a light emission surface is formed at an end portion of the light guide plate at a portion where the portions are adjacent to each other, and the inclination when viewed from the light emission surface side of the light guide plate It has a light irradiation part which is arrange | positioned so that it may overlap with a surface and inject | emits light with respect to the said inclined surface, It is characterized by the above-mentioned. The light guide plate may be used alone, or may be one in which a plurality of light guide plates are arranged side by side to form a large panel.

  Furthermore, in order to solve the above technical problem, another surface light emitting device of the present invention is made of a substantially flat transparent plate material, and is a pair of inclined surfaces inclined obliquely with respect to the main surface serving as a light emitting surface. A light guide plate formed so as to form a groove or a hole having a substantially V-shaped cross section, and the light guide plate disposed so as to overlap the groove when viewed from the light exit surface side of the light guide plate. And a light irradiator for emitting light.

  According to the surface light-emitting device of the present invention, when the light irradiation part is viewed from the light emission surface side of the light guide plate, the inclination is inclined by the end portion having the inclined surface that is inclined with respect to the main surface serving as the light emission surface. Even if it is arranged so that at least a part of the surface overlaps, most of the light that is directly transmitted from the light irradiation part to the light exit surface side of the light guide plate is suppressed, and the light is reflected in the in-plane direction of the light guide plate. Can be. As a result, for the central part of the light irradiation surface that tends to be dark only by arranging a light source around it, for example, by adopting a device structure in which light guide plates are arranged side by side, an end portion having an inclined surface is within the light emission surface. Thus, it is possible to prevent the lowering of the luminance at the center, and thus the size of the display device can be increased.

  Preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a main part of the surface light emitting device according to the present embodiment. As shown in FIG. 1, in the surface light emitting device of this embodiment, a plurality of light emitting diode elements 11 functioning as a light emitting portion are arranged in a substantially straight line, and a pair of light guide plates 12 and 13 are formed in a straight line. It is set as the structure arrange | positioned by the both sides of the several light emitting diode element 11 arranged in order.

  The light emitting diode element 11 has a structure in which light is emitted in a substantially normal direction of the light emitting surfaces 18 and 19 of the light guide plates 12 and 13 which are upward in FIG. The light emitting diode element 11 is shown in a cylindrical shape in FIG. 1, but may have other shapes, for example, a structure having a flat or bullet light generating portion. Other structures may be used as long as the light emitting diode has a structure that emits light in a substantially normal direction of the light exit surfaces 18 and 19 of the light guide plates 12 and 13.

  At the end portions of the light guide plates 12 and 13, inclined surfaces 14 and 15 that are inclined obliquely with respect to the main surface serving as a light exit surface are formed. The inclined surfaces 14 and 15 are formed with an inclination of 30 to 60 degrees, more preferably 40 to 50 degrees with respect to the light exit surfaces 18 and 19 of the light guide plates 12 and 13. Abutting surfaces 16 and 17 are formed at the ends of the light guide plates 12 and 13 on the upper side of the inclined surfaces 14 and 15, and the pair of light guide plates 12 and 13 are joined in such a manner that the abutting surfaces 16 and 17 are abutted. The light emission surfaces 18 and 19 of the light guide plates 12 and 13 are supported so as to be flush with each other.

  Here, the light guide plates 12 and 13 are plate-shaped members made of transparent synthetic resin each having a light emitting surface 18 and 19 facing each other and a reflecting surface which is the back side of the light emitting surface as main surfaces, and are not shown. However, a reflecting plate is formed at a position facing the reflecting surface, and reflecting dots for reflecting the light introduced from the side portion toward the light emitting surfaces 18 and 19 are also formed. Examples of the constituent materials of the light guide plates 12 and 13 include polyester resin, amorphous polyester resin, acrylic resin such as polymethyl methacrylate (PMMA), polycarbonate resin, polystyrene resin (PS), styrene / acrylonitrile resin (SAN), urethane. Various transparent polymer materials such as resin, cycloolefin resin, alicyclic polyolefin resin, cyclic polyolefin resin, alicyclic acrylic resin, amorphous fluororesin, epoxy resin, polyimide resin, polyamide resin, vinyl ester resin And a combination of these modified materials and a plurality of resin materials may be used. Moreover, you may have a structure which contains a fluorescent material in part or the whole surface of a light-guide plate.

  Moreover, in this embodiment, since it is necessary to form the inclined surfaces 14 and 15 in an edge part, the transparent board | plate material cut | disconnected diagonally and the transparent board | plate material which has the thickness of about butting | matching surfaces 16 and 17, for example are bonded together These composite materials can also be used. Further, a structure may be adopted in which a reflection dot for reflecting light introduced from the side portion to the light emitting surfaces 18 and 19 side and a sheet for scattering light are interposed in the bonded portion of the two plate members. It is also possible to form an antireflection film or the like on the inclined surfaces 14 and 15.

  FIG. 2 is a plan view showing a device in which the surface light emitting devices having such a structure are arranged in a plane, and is a surface light emitting device having a large light emitting area as a whole. As shown in FIG. 2, light guide plates 20 each having a substantially rectangular shape are arranged in a plane so as to form two rows and three columns, and light is emitted in the horizontal direction at the outer peripheral portion of these six assemblies. A light irradiating portion 21 having a direction is formed, and the light irradiation is arranged such that an inclined surface is formed at the boundary portion outside the outer periphery of these six aggregates and a part of the inclined surface is overlapped with the inclined surface. Part 22 is formed. In the light irradiation unit 22, the light emission direction is the normal direction of the main surface of the light guide plate.

  By arranging the light irradiation unit 22 so as to overlap in a region between the adjacent light guide plates 20 where the inclined surfaces are formed, the light emitted from the light irradiation unit 22 is reflected by the inclined surface portion, and the light guide plate 20 The light is reflected in the in-plane direction and further reflected by a reflection dot (not shown) of the light guide plate 20 to cause the light emission surface of the light guide plate 20 to emit light. At this time, since the position of the light irradiation unit 22 is inside the surface light emitting device having a large light emitting area, the distance from the light irradiation unit 22 is relatively close even in a portion close to the center portion. It is possible to prevent the central portion of the screen from becoming dark. When the direction of the light guide plate is viewed from the light emission side, most of the light from the light irradiation unit 22 on the back surface side is reflected by the inclined surface and does not directly transmit, so that the light emission direction of the light irradiation unit 22 is Regardless of the normal direction of the main surface of the light guide plate, the inclined surface portion emits light with the same brightness as the other portions, and the uniformity of the surface light distribution is excellent.

  FIG. 3 is a diagram illustrating a positional relationship between the light irradiation unit and the light guide plate. The light emitting diode element 31 constituting the light irradiating portion has a substantially cylindrical shape, and is circular when viewed from the light exit surface side of the light guide plate 32 as shown in FIG. For example, the light emitting diode element 31 is a part of a light irradiation section in which a plurality of elements are arranged in a straight line. The light emitting diode elements 31 are arranged in a positional relationship such that the hemispherical portion overlaps the end of the light guide plate 32 when viewed from the light exit surface side of the light guide plate 32. On the side protruding from the light guide plate in FIG. 3, the other light guide plate is similarly disposed so as to overlap the light emitting diode element 31.

  FIG. 4 is a cross-sectional view showing an example of another surface emitting device. Light guide plates 44 and 46 having inclined surfaces 45 and 47 at their ends are arranged so as to be arranged in a plane, and the light emission direction is guided corresponding to the region where the pair of inclined surfaces 45 and 47 are located. A light emitting diode element 43 on the surface side of the light plates 44 and 46 is attached. Further, the left end of the light guide plate 44 in the drawing is an end not adjacent to another light guide plate, and the light guide diode 44 has the light emission direction in the in-plane direction of the light guide plate at the end of the light guide plate 44. An element 42 is provided. Further, on the bottom side of each light guide plate 44, 46, there are provided reflection plates 48, 49 for reflecting light reflected from the light guide plate to the back surface side.

  Thus, it can be set as the structure which makes light inject from the light emitting diode elements 42 and 43 used as the some light emission part with respect to the one light guide plate 44, and especially the light emission direction of the light emitting diode element 43 is the light guide plate 44, In spite of the normal direction of the main surface of 46, the inclined surfaces 45 and 47 emit light with the same brightness as the other portions, and the uniformity of the surface light distribution is excellent. Become.

  FIG. 5 is an example of another surface light emitting device, and a V-shaped groove or hole 53 having a pair of inclined surfaces facing each other corresponding to a light emitting diode element 51 that emits light is formed in the light guide plate 52. Is done. Even if a groove or hole 53 having a V-shaped cross section is formed at a position other than the end portion of the light guide plate 52, the light emission direction of the light emitting diode element 51 is the same as in the surface light emitting device having an inclined surface at the end portion. Despite the normal direction of the main surface of the light guide plate 52, the inclined surface portion emits light with the same brightness as the other portions, and the surface light distribution has excellent uniformity of light distribution. Become. Therefore, it is extremely advantageous when configuring a large-screen display device.

It is a perspective view which shows an example of the surface light-emitting device of this invention. It is a top view which shows another example of the surface emitting device of this invention. It is a top view which shows the principal part of another example of the surface emitting device of this invention. It is a top view which shows another example of the surface emitting device of this invention. It is sectional drawing which shows another example of the surface emitting device of this invention.

Explanation of symbols

11, 31, 42, 43, 51 Light-emitting diode element 12, 13, 20, 32, 44, 46, 52 Light guide plate 14, 15, 45, 47 Inclined surface 53 Hole

Claims (8)

A light guide plate formed of a substantially flat transparent plate material and having an inclined surface inclined at an angle with respect to a main surface serving as a light emission surface;
A surface light emitting device comprising: a light irradiating unit that is disposed so as to at least partially overlap the inclined surface when viewed from the light emitting surface side of the light guide plate, and emits light to the inclined surface. apparatus. 2. The surface light emitting device according to claim 1, wherein the light irradiation unit has a structure in which a plurality of light emitting diode elements are arranged in a substantially straight line. 2. The surface light emitting device according to claim 1, wherein an inclination angle of the inclined surface with respect to a main surface serving as the light emitting surface is an angle of 30 to 60 degrees. A plurality of substantially rectangular light guide plates made of a transparent plate and arranged side by side in a flat plate shape, and inclined at an angle with respect to the main surface serving as a light exit surface at a portion where the end portions of the light guide plates are adjacent to each other A light irradiating portion that is formed on an end portion of the light guide plate and disposed so as to overlap the inclined surface when viewed from the light emitting surface side of the light guide plate, and emits light to the inclined surface; A surface light emitting device comprising: 5. The surface light emitting device according to claim 4, wherein the light irradiation unit has a structure in which a plurality of light emitting diode elements are arranged in a substantially straight line. The light from the second light irradiating unit is introduced in the direction in which the light guide plate extends from the side surface of the light guide plate at the end of the light guide plate where the ends of the light guide plates are not adjacent to each other. 4. The surface light-emitting device according to 4. A light guide plate made of a substantially flat transparent plate material and formed so as to form a pair of inclined surfaces inclined obliquely with respect to the main surface serving as a light emission surface in a groove or hole having a substantially V-shaped cross section;
A surface light emitting device, comprising: a light irradiating unit that is disposed so as to overlap the groove when viewed from the light emitting surface side of the light guide plate and emits light to the inclined surface. 8. The surface light emitting device according to claim 7, wherein the light irradiation unit has a structure in which a plurality of light emitting diode elements are arranged in a substantially straight line.