JP2007128114A - Planar lighting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem in which a conventional planar lighting apparatus used for a transmissive liquid crystal display with a large display area is difficult to obtain a uniform light distribution characteristic and liable to increased electric power consumption. <P>SOLUTION: A planar lighting apparatus is equipped with a light guiding block 11 including: a light incident end face 15; a light emitting end face 16 situated opposite to the light incident end face 15 and provided with an area larger than the light incident end face 15; four side end faces 17, 18 which are situated between the light incident end face 15 and the light emitting end face 16 and which include a pair of slopes; and a plurality of prism bodies which are projectingly formed on the pair of slopes and which contain an apex extending in parallel to the light emitting end face 16. The apparatus is also equipped with a linear fluorescent lamp 14 which opposes the light incident end face 15 of this light guiding block 11 and which extends in parallel to the apex of the prism bodies, and equipped with a reflector 27 which surrounds this fluorescent lamp 14 and the light incident end face 15. A distance from the light emitting end face 16 of the light guiding block 11 to the fluorescent lamp 14 is set larger than the thickness of the light guiding block 11 along the direction perpendicular to the light emitting end face 16. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flat illumination device for emitting light introduced from a light incident end surface portion of a light guide block from a light emitting end surface portion opposed to the light incident end surface portion, and more particularly to a light emitting end surface portion having a large area. This is suitable for emitting light uniformly from the entire region.

  As a flat illumination device used as a light source of a transmissive liquid crystal display device, various forms are used according to the display area of the liquid crystal display device. However, in order to reduce power consumption, a fluorescent lamp or LED array is used as a light source, and the flat illumination device is made flat in order to make the flat illumination device compact in the depth direction and at the same time obtain uniform light distribution characteristics on the liquid crystal display surface. In most cases, a light guide plate having a shape is used, and light from a light source incident from the side end face of the light guide plate is uniformly emitted from the surface of the light guide plate. On the front and back surfaces of such a light guide plate, minute irregularities for changing the propagation characteristics of light propagating in the light guide plate and the light emission direction from the surface of the light guide plate are formed in a predetermined pattern, Thereby, substantially uniform light can be emitted from the entire surface of the light guide plate.

  With the advancement of liquid crystal technology, liquid crystal display devices having a very large display area can be manufactured. In such a large transmissive liquid crystal display device, even if fluorescent lamps are arranged on all side end surfaces of the light guide plate, the amount of light at the center of the liquid crystal display surface is insufficient, and is uniform over the entire display surface. It is difficult to have a good light distribution characteristic. For this reason, as a flat illumination device used for a transmissive liquid crystal display device with a very large display area, a light source such as a fluorescent lamp is arranged on the back surface of the liquid crystal display device through a diffuser plate, and this is covered with a reflector. Things have become commonplace.

  A large light guide plate with minute irregularities to change the propagation characteristics of light propagating inside and the light emission direction from the surface in a predetermined pattern is fundamentally impossible to roll forming, so it is manufactured by injection molding However, as the area of the light guide plate is increased, the molding pressure must be increased, and an extremely large injection molding apparatus is required, resulting in a disadvantage that the equipment cost increases.

  In the case of a structure in which a light source is arranged between the diffuser plate and the reflector, it is necessary to increase the distance from the diffuser plate to the light source to some extent in order to have uniform light distribution characteristics over the entire area of the diffuser plate. The light from the light propagates in the air to the diffuser plate. For this reason, in combination with the use of a diffuser plate, the attenuation of light is large, and even if uniform light distribution characteristics are obtained over the entire area of the diffuser plate, in order to obtain sufficient illuminance It is necessary to use a light source with high power consumption. Conversely, when the light source is arranged close to the diffuser plate, the intensity of the light emitted from the diffuser plate can be secured to some extent, but the uniform light distribution characteristics over the entire area of the diffuser plate. It is virtually impossible to have.

  An object of the present invention is to provide a low power consumption flat illumination device capable of obtaining uniform light distribution characteristics even for a transmissive liquid crystal display device having a large display area.

  Another object of the present invention is to provide a low power consumption flat illumination device having a uniform light distribution characteristic capable of arbitrarily changing an illumination area.

  The first embodiment of the flat illumination device according to the present invention is formed of a cylindrical concave lens surface, is located on the opposite side of the light incident end surface portion where light enters, and from the light incident end surface portion. A light emitting end face part from which light is emitted, and a plurality of light deflecting elements that are randomly formed on the light emitting end face part and deflect the light emitting direction from the light emitting end face part, Located between the light incident end surface portion and the light emitting end surface portion, four side end surface portions including a pair of inclined surfaces, and protruding from the pair of inclined surfaces, are parallel to the light emitting end surface portion. And a plurality of prism bodies each having a first inclined surface portion facing the light incident end face portion side and a second inclined surface portion on the opposite side thereof, each of which deflects the traveling direction of light. Including light guide block and this guide A light source end face of the light guide block comprising a linear light source facing the light incident end face of the block and extending in parallel with the top of the prism body, and a reflector surrounding the light source and the light incident end face The distance from the light source to the light source is set to be larger than the thickness of the light guide block along the direction perpendicular to the light emitting end face.

  The light guide block used in the present invention is made of an optically transparent resin such as PMMA, PC, zeonor (trade name: Nippon Zeon Co., Ltd.), Arton (trade name: JSR Co., Ltd.) or the like other than optical glass. Can be manufactured.

  In the planar illumination device according to the first aspect of the present invention, the light deflection element of the light guide block has an isosceles triangular opening whose base is parallel to the central axis of curvature of the concave lens surface of the light incident end face portion, It may be a triangular pyramid-shaped recess having a pair of conical surfaces perpendicular to the end surface portions and an inclined conical surface including the base. In this case, it is effective that the light deflection element of the light guide block is formed so as to have a larger occupation ratio toward the center of the light emitting end face.

  The flat illumination device according to the second aspect of the present invention has a light incident end surface portion on which light is incident, an opposite side of the light incident end surface portion and a larger area than the light incident end surface portion. A light exit end face to emit, a plurality of light deflection elements randomly formed on the light exit end face to deflect the light exit direction from the light exit end face, the light entrance end face and the light exit Four side end surface portions including a pair of inclined surfaces, a top portion formed in a protruding state on the pair of inclined surfaces, and extending in parallel with the light emitting end surface portion, and the top portion. A first slope part facing the light incident end face part side and a second slope part opposite to the first slope part as a boundary, and a plurality of prism bodies each deflecting the traveling direction of light, and the light exit end face part with respect to the light exit end face part The inclination angle of the pair of inclined surfaces is the light emitting end surface. A light guide block set larger toward the side, a linear light source facing the light incident end surface portion of the light guide block and extending in parallel with the top of the prism body, and the light source and the light incident end surface portion. A distance from the light emitting end surface portion of the light guide block to the light source is set to be larger than the thickness of the light guide block along a direction perpendicular to the light emitting end surface portion. It is characterized by.

  A third embodiment of the flat illumination device according to the present invention has a light incident end face part on which light is incident, an opposite side of the light incident end face part and a larger area than the light incident end face part. A light exit end face to emit, a plurality of light deflection elements randomly formed on the light exit end face to deflect the light exit direction from the light exit end face, the light entrance end face and the light exit Four side end surface portions including a pair of inclined surfaces, a top portion formed in a protruding state on the pair of inclined surfaces, and extending in parallel with the light emitting end surface portion, and the top portion. A plurality of prism bodies each having a first inclined surface portion facing the light incident end surface portion side and a second inclined surface portion on the opposite side as a boundary and deflecting the traveling direction of light, and the light emitting end surface portion and the The angle formed by the second slope of the prism body is the light incident A light guide block that is set to be larger toward the light emission end face along the facing direction between the end face and the light emission end face, and the light incident end face of the light guide block, and the top of the prism body A linear light source extending in parallel and a reflector surrounding the light source and the light incident end surface portion, and a distance from the light emitting end surface portion of the light guide block to the light source is relative to the light emitting end surface portion The thickness of the light guide block is set to be greater than the thickness of the light guide block along the vertical direction.

  In the present invention, the light emitted from the light source is incident on the light guide block from the light incident end face without waste by the reflector, and the light is emitted through the light guide block toward the light exit end face while repeating total reflection at the side end face. Propagate. In the middle, the light propagation direction is partially deflected and diffused by the prism body formed on the side end face, and the light whose emission direction is controlled by the light deflecting element formed on the light exit end face is emitted. The light is emitted almost uniformly over the entire end face.

  In the flat illumination device according to the second or third aspect of the present invention, the proportion of the area of the light deflection element per unit area of the light exit end face of the light guide block increases as the distance from the light entrance end face increases. It is preferable that it is set.

  The light incident end face portion may be a convex surface or a concave surface other than a flat surface, and may be formed of, for example, a conical surface, a truncated cone surface, a lens surface or a lenticular surface thereof, or a lenticular prism surface. When the light incident end face portion is composed of a lenticular lens surface or a lenticular prism surface, it is effective to change the characteristics and distribution of individual optical elements between the central portion and the outer peripheral edge portion of the incident end face portion. A surface is preferable in terms of ease of manufacture and effects.

  The flat illumination device according to the present invention may further include a light reflecting cover that is formed integrally with the reflector and covers the periphery of the light guide block other than the light incident end face and the light exit end face. In this case, the light guide block further includes at least a pair of connection end surface portions that are formed between the light output end surface portion and the side end surface portions and are respectively perpendicular to the light output end surface portion, and at least two light guide blocks. May be integrally connected via these connection end surfaces, and the light reflection cover may cover the periphery of the integrally connected light guide blocks. In this case, one of the pair of connection end surface portions of the light guide block may have a locking projection, and the other may have a locking recess having a shape corresponding to the locking projection.

  You may make it set the space | interval of the prism body along the opposing direction of the light-incidence end surface part of a light guide block, and a light-projection end surface part as the light-projection end surface part side narrows.

  You may make it set the height of the top part of the prism body of a light guide block so that the light-projection end surface part side may become high along the opposing direction of a light-incidence end-face part and a light-projection end-face part.

  The light deflection element of the light guide block may be convex or concave with respect to the light emitting end face, and forms a part of a spherical surface, a circular or polygonal columnar shape or a conical shape (prism shape). It may be.

  A light reflection layer formed on the surface of the side end surface portion of the light guide block may be further provided. In this case, the light reflecting layer has a metal or a white inorganic substance, and can be formed by vapor deposition, sputtering, coating, or adhesion.

  According to the first aspect of the flat illumination device of the present invention, light that has entered the light guide block from the light incident end face portion is efficiently diffused by the prism body while propagating through the light guide block toward the light exit end face portion. In addition, the light deflection element can emit light with a substantially uniform light amount from the entire area of the light emitting end face. Further, the light that has entered the light guide block from the light incident end face can be efficiently diffused toward the light exit end face. As a result, light from the light source can be emitted from the entire area of the light emitting end face with a substantially uniform light amount.

  According to the 2nd form of the planar illuminating device of this invention, the ratio of the light which totally reflects toward the light emission end surface part side among the light which propagates the inside of a light guide block is increased, so that it approaches the light emission end surface part side. Therefore, it is possible to increase the amount of light emitted from the outer peripheral edge portion relative to the central portion of the light emitting end surface portion, and to obtain a more uniform light amount over the entire area of the light emitting end surface portion. Light can be emitted.

  According to the 3rd form of the planar illuminating device of this invention, since the ratio by which the total reflection conditions of the light which propagates the inside of a light guide block are violated increases so that it approaches the light-projection end surface part side, the center part of a light-projection end surface part On the other hand, the amount of light emitted from the outer peripheral edge can be relatively increased, and a more uniform amount of light can be emitted from the entire area of the light emitting end face.

  When the light reflection cover that is formed integrally with the reflector and covers the periphery of the light guide block other than the light incident end face part and the light output end face part is further provided, the light leaks to the outside from the side end face part of the light guide block. Light can be reintroduced into the light guide block, thereby minimizing the loss of light from the light source.

  The light guide block includes at least a pair of connection end surface portions that are formed between the light output end surface portion and the side end surface portions and are respectively perpendicular to the light output end surface portion, and at least two light guide blocks have these connection end surfaces. When the light-reflecting cover covers the integrally connected light guide blocks, the flat illumination device having an arbitrary illumination area can be easily configured. .

  If the ratio of the area of the light deflection element per unit area of the light exit end face is set to increase as the distance from the light entrance end face increases, the light totally reflected at the light exit end face is Since there exists a tendency to radiate | emit from a light-projection end surface part by presence, the light of a more uniform light quantity can be radiate | emitted over the whole region of a light-projection end surface part.

  The interval between the prism bodies along the opposing direction of the light incident end face portion and the light exit end face portion is set closer to the light exit end face portion side, or the height of the top of the prism body is set to the light incident end face portion and the light exit end face portion. If the light exit end face side is set higher along the facing direction of the light, the ratio of breaking the total reflection condition of the light propagating in the light guide block increases as it approaches the light exit end face side. The amount of light emitted from the outer peripheral edge portion can be relatively increased with respect to the central portion of the end surface portion, and a more uniform amount of light can be emitted from the entire area of the light emitting end surface portion.

  Embodiments of the flat illumination device according to the present invention will be described in detail with reference to FIGS. 1 to 8, but the present invention is not limited to these embodiments, and further combinations thereof, or claims of this specification Any change or modification included in the concept of the present invention described in the scope of the present invention can be made, and can naturally be applied to any other technique belonging to the spirit of the present invention.

  The appearance of the first embodiment of the flat illumination device according to the present invention is shown in an exploded state in FIG. 1, and its cross-sectional structure is shown in FIG. That is, the planar illumination device in the present embodiment is a pair of light guide blocks 11 each having a substantially isosceles triangular prism shape, a frame body 12 surrounding the outer peripheral edge of the light guide block 11, and the frame body 12. And a pair of casings 13 in which the light guide blocks 11 are respectively housed, and a pair of fluorescent lamps 14 that are housed in the casings 13 and are connected to a power source (not shown) as a light source of the present invention. Yes.

  The side shape of the light guide block 11 in the present embodiment is shown in FIG. 3, and an arrow IV part in FIG. 2 is extracted and enlarged and shown in FIG. That is, the light guide block 11 in this embodiment is formed of an optically transparent acrylic resin (PMMA) having a refractive index of about 1.4 to 1.7, and light from the fluorescent lamp 14 that is a light source is incident thereon. An elongated light incident end face portion 15, a rectangular light emitting end face portion 16 which is located on the opposite side of the light incident end face portion 15 and has a larger area than the light incident end face portion 15 and emits light, and a light incident 1st and 2nd side end surface parts 17 and 18 located between the end surface part 15 and the light emission end surface part 16, and between the light emission end surface part 16 and the 1st side end surface part 17, light emission And a pair of connection end surface portions 19 each perpendicular to the end surface portion 16.

  The elongated light incident end face 15 of the present embodiment facing the fluorescent lamp 14 and having a length substantially equal to the fluorescent lamp 14 has a cylindrical concave lens surface whose center axis of curvature (not shown) is parallel to the longitudinal direction of the fluorescent lamp 14. The light entering the light guide block 11 from here is taken into consideration in a plane perpendicular to the central axis of curvature of the cylindrical concave lens surface.

  The pair of first side end surface portions 17 are formed by a pair of inclined surfaces having a plane that passes through the central axis of curvature of the cylindrical concave lens surface and is perpendicular to the light emitting end surface portion 16 as symmetry planes. The end surface portion 18 is perpendicular to the central axis of curvature of the cylindrical concave lens surface.

  When the light incident end face portion 15 is formed as a flat surface, the light entering the light guide block 11 from here becomes the refractive index of the material constituting the light guide block 11 in a plane parallel to the second side end face portion 18. The incident critical angle depends on the angle, that is, it does not physically diffuse beyond the total reflection angle, so that the opening angle γ of the pair of first side end face portions 17 is larger than the total reflection angle of the material constituting the light guide block 11 In particular, when the distance from the light emitting end face portion 16 to the fluorescent lamp 14 that is a light source is set short to reduce the thickness of the flat illumination device, the opening angle γ of the pair of first side end face portions 17 is guided to the light guide block. 11 needs to be larger than the total reflection angle of the material constituting 11. In such a case, the light incident end face portion 15 is formed on the cylindrical concave lens surface as described above, thereby guiding the light incident into the light guide block 11 according to the opening angle γ of the pair of first side end face portions 17. It becomes possible to diffuse the entire area of the optical block 11.

  On one of the pair of connection end surface portions 19 extending in parallel with the central axis of curvature of the cylindrical concave lens surface, a plurality of locking convex portions 20 having a truncated cone shape are spaced apart along the longitudinal direction of the connection end surface portion 19. (Two in the illustrated example) are formed, and the other connecting end surface portion 19 has locking concave portions 21 having shapes corresponding to these locking convex portions 20 spaced apart along the longitudinal direction of the connecting end surface portion 19. A plurality (two in the illustrated example) are formed. The positions of the locking projections 20 and the locking recesses 21 formed on each connection end surface portion 19 are such that the locking projections 20 formed on one connection end surface portion 19 of the plurality of light guide blocks 11 are guided to the other light guide. When fitted into a locking recess 21 formed in the other connection end surface portion 19 of the block 11, the connection end surface portions 19 of these two light guide blocks 11 are completely overlapped, and light emission of the two light guide blocks 11 is performed. The end face portion 16 is set to be completely on the same plane without a step.

  A plurality of light deflection elements 22 for deflecting the light emission directions from the light emission end face portion 16 are randomly formed on the light emission end face portion 16, and the light deflection element 22 in this embodiment is a spherical surface. A partially formed convex spherical shape having a radius of about several tens of micrometers and protrudes from the surface of the light emitting end face 16 by about several micrometers. The dimensions, distribution, and the like of these light deflection elements 22 are appropriate so that the diffusion angle, brightness, and brightness of the light emitted from the light emission end face portion 16 are substantially uniform over the entire area due to the presence of the light deflection elements 22. Is set to The light deflecting element 22 may be concave with respect to the light emitting end face portion 16 as long as it can achieve such an object, and may have a circular or polygonal columnar shape or a conical shape. The occupation ratio of the light deflection element 22 per unit area of the light exit end face portion 16 is such that the distance from the center is a plane perpendicular to the light exit end face portion 16 passing through the central axis of curvature of the cylindrical concave lens surface. The distribution shown in FIG. 5 is basically provided so that the linear distance from the incident end face portion 15 increases as the distance increases.

  A plurality of prism bodies 23 for deflecting the light traveling directions are formed on the first side end face portion 17. Similar to the light deflection element 22, these prism bodies 23 also have a diffusion angle, brightness, and brightness of light finally emitted from the light emitting end face portion 16 so as to be almost uniform over the entire area due to the presence of the prism body 23. It is set properly. In this embodiment, the prism body 23 includes a top 24 extending in parallel with the light emitting end face 16, a first inclined face 25 facing the light incident end face 15 with the top 24 as a boundary, and a second on the opposite side. And a slope portion 26. In the present embodiment, the interval P between the prism bodies along the facing direction of the light incident end face 15 and the light exit end face 16 is set to be narrower toward the light exit end face 16 side. It is also effective to form such a prism body 23 on the second side end face portion 18.

  The height of the apex 24 of the prism body is set so that the light incident end face 15 and the light exit end face 16 have a uniform diffusion angle, brightness, and brightness over the entire region. Of the light emitting end face 16 and the angle θ formed by the light emitting end face 16 and the second inclined surface 26 of the prism body is set to the light incident end face 15 and the light emitting end face 16. The light emission end face 16 side may be set to be larger along the facing direction.

  Accordingly, by appropriately adjusting the dimensions, distribution, and the like of the light deflection element 22 and the prism body 23, the light emitted from the light emission end face portion 16 is diffused only in a desired direction, and the luminance distribution and brightness are also arbitrary. It becomes possible to set to.

  In the present embodiment, the pair of first side end surface portions 17 are each formed as a flat surface. However, the opening angle γ of the pair of first side end surface portions 17 decreases continuously or stepwise toward the light emitting end surface portion 16 side. You may make it set so that it may become. That is, in the case of the light guide block 11 in which the opening angle γ of the pair of first side end surface portions 17 is set to be larger than the maximum refraction angle of incident light, the light amount and luminance emitted from the central portion of the light emitting end surface portion 16 are the first. It tends to be larger than the amount of light and luminance emitted from both side edges of the light emitting end face portion 16 adjacent to the side end face portion 17. For this reason, the light emission end face part 16 is relatively increased in light quantity and luminance emitted from both side edges of the light emission end face part 16 so that the light emission end face part 16 has a uniform light quantity and luminance over the entire area. It is effective to reduce the opening angle γ of the first side end face portion 17 close to the side and totally reflect the incident light incident on the light guide block 11 here. This is because the angle θ formed by the light emitting end face portion 16 and the second inclined surface portion 26 of the prism body is set to be larger toward the light emitting end face portion 16 side along the opposing direction of the light incident end face portion 15 and the light emitting end face portion 16. It is the same as that.

  The casing 13 covers the reflector 27 for efficiently reflecting the light emitted from the fluorescent lamp 14 to the light incident end face portion 15 of the light guide block 11, and the first and second side end face portions 17 and 18 of the light guide block 11. The inner peripheral surface of the light reflection cover 28 is subjected to a treatment such as metal plating or white coating so that light leaked from the light guide block 11 is incident on the light guide block 11 again. The light reflecting cover 28 in this embodiment surrounds the periphery of the light incident end face 15 of the light guide block 11 that is connected to each other and is subjected to the same reflection treatment as the inner peripheral surface of the light reflecting cover 28. The body 12 is integrally joined, and the frame body 12 has a width dimension substantially corresponding to the width of the connection end surface portion 19. The frame body 12 is formed with a positioning recess 29 and a positioning protrusion 30 that are locked to the locking protrusion 20 and the locking recess 21 of the connection end surface 19 that are not involved in the connection of the light guide block 11, respectively. Thus, the light guide block 11 can be accurately positioned with respect to the frame 12. The frame body 12 and the light reflection cover 28 adopt a fitting structure in this embodiment so that light does not leak to the outside from these coupling portions, and these are integrally joined by an adhesive (not shown) or the like. The

  Therefore, the light emitted from the fluorescent lamp 14 enters the light guide block 11 from the light incident end face portion 15 by the reflector 27. The angle of the incident angle more than the incident critical angle is obtained by the action of the cylindrical concave lens surface of the light incident end face portion 15. And propagates in the light guide block 11 toward the light emitting end face 16 side. The light leaked to the outside from the first and second side end surface portions 17 and 18 and the connection end surface portion 19 is incident on the light guide block 11 again by the inner surface treatment of the light reflecting cover 28 and the frame body 12, and finally All the light exits from the light exit end face 16 of the light guide block 11. In this case, the diffusion angle, brightness, and brightness of the light emitted from the light emitting end face portion 16 are substantially uniform over the entire area due to the presence of the prism body 23 and the light deflection element 22.

  In the embodiment described above, the pair of second side end face portions 18 is set perpendicular to the central axis of curvature of the cylindrical concave lens surface. However, when a point light source such as an LED or a light bulb is employed as the light source, The second side end face portion 18 can also be inclined in the same manner as the first side end face portion 17 so that the light guide block 11 can be formed in a frustum shape as a whole. In this case, a connection end surface portion similar to the connection end surface portion 19 described above is also formed between the light emitting end surface portion 16 and the second side end surface portion 18 so that the light guide block 11 can be connected in two directions. It is also possible to make it. Thus, when the side end surface parts 17 and 18 are conical surfaces, the light from the point light source can be efficiently introduced into the light guide block 11.

  In the embodiment described above, the planar illumination device is configured by combining a plurality of light guide blocks 11 in order to increase the illumination area, but it is also possible to configure the planar illumination device using only a single light guide block 11. It is. The external appearance of another embodiment of the flat illumination device according to the present invention is shown in FIG. 6 in an exploded state, and the planar shape of the arrow VII portion is extracted and enlarged in FIG. Although the appearance of 22 is extracted and enlarged in FIG. 8, elements having the same functions as those in the previous embodiment are denoted by the same reference numerals, and redundant description is omitted.

  That is, the opening angle γ of the pair of first side end surface portions 17 in the present embodiment is set to be larger than the opening angle of the pair of first side end surface portions 17 in the previous embodiment. In this case, the light exiting from the light exit end face portion 16 as it is without being totally reflected tends to increase. Therefore, the light deflecting element has a function of totally reflecting the light in the propagation direction which is emitted from the light emitting end face portion 16 as it is without being totally reflected in the light guide block 11 to the connection end face portion 19 or the first side end face portion 17 side. 22 so that the diffusion angle, brightness, and brightness of the light emitted from the light emitting end face portion 16 are made uniform. The light deflecting element 22 in the present embodiment is in a state where a plurality of types are mixed, and has a convex spherical shape having a radius of about several tens of micrometers formed by a part of a spherical surface as in the previous embodiment. In addition, the base 31 has an isosceles triangular opening parallel to the central axis of curvature of the cylindrical concave lens surface, a pair of conical surfaces 32 each perpendicular to the light emitting end face portion 16, and the base edge whose upper edge is the above-mentioned base A concave portion having a triangular pyramid shape having an inclined conical surface 33 which is 31 is provided. The connection end face transmits light in the propagation direction such that the inclined conical surface 33 of the light deflection element 22 formed by the triangular pyramid-shaped recess does not totally reflect in the light guide block 11 and exits from the light exit end face 16 as it is. It has a function of totally reflecting toward the part 19 and the first side end face part 17 side. The light deflecting element 22 formed by the triangular pyramid-shaped concave portion is randomly formed so as to have a larger occupation ratio mainly toward the central portion side of the light emitting end surface portion 16 of the light guide block 11, and forms a convex spherical shape. The elements 22 are formed randomly so that the occupancy is mainly larger toward the connection end face 19 side of the light emitting end face portion 16.

  In the present embodiment, connection end surface portions 19 and 34 are formed on the entire circumference of the light guide block 11, and the elongated locking projection 20 and the locking recess 21 extending along the long side of the light emitting end surface portion 16. And a pair of flat connection end surface portions 34 extending along the short side of the light emitting end surface portion 16. You may make it form the latching convex part 20 and the latching recessed part 21 also in a pair of flat connection end surface part 34. FIG. In this embodiment, since the fluorescent lamp 14 serving as the light source has a length shorter than the length of the long side of the light emitting end surface portion 16, the pair of second side end surface portions 18 are replaced with the pair of first end surfaces. As in the case of the side end surface portion 17, the light incident end surface portion 15 is made to correspond to the length of the fluorescent lamp 14 serving as a light source. Therefore, the light guide block 11 in this embodiment has a substantially truncated pyramid shape.

  In the two embodiments described above, when a light reflecting layer containing a white inorganic substance such as metal or titanium oxide is formed on the surfaces of the first and second side end face portions 17 and 18 of the light guide block 11. Can eliminate light leakage from the first and second side end surface portions 17 and 18 to the outside of the light guide block 11, so that the light emitting end surface portion 16 can be suppressed. Thus, light can be emitted efficiently.

It is a disassembled perspective view showing the external appearance of one Example of the plane illuminating device by this invention. It is sectional drawing of the plane illuminating device in the Example shown in FIG. It is a side view of the light guide block in the Example shown in FIG. FIG. 4 is an extracted enlarged cross-sectional view taken along the arrow IV in FIG. 2. It is a graph showing the occupation rate of the optical deflection | deviation element in the Example shown in FIG. It is a disassembled perspective view showing the external appearance of the other Example of the planar illuminating device by this invention. It is an extraction expansion top view of the arrow VII part in FIG. It is an expansion perspective view showing the external appearance of the light deflection | deviation element shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Light guide block 12 Frame 13 Casing 14 Fluorescent lamp 15 Light incident end surface part 16 Light emission end surface part 17, 18 Side end surface part 19 Connection end surface part 20 Locking convex part 21 Locking concave part 22 Light deflection element 23 Prism body 24 Top part 25 First slope part 26 Second slope part 27 Reflector 28 Light reflection cover 29 Positioning concave part 30 Positioning convex part 31 Bottom 32 Conical surface 33 Inclined conical surface 34 Connection end face part γ Opening angle of first side end face part θ Light emitting end face part Between the first and second slopes P The distance between the prism bodies

Claims (11)

A light emitting end surface that is formed by a cylindrical concave lens surface and has an elongated light incident end surface portion on which light is incident, and is located on the opposite side of the light incident end surface portion and has a larger area than the light incident end surface portion. An end face part, a plurality of light deflection elements randomly formed on the light exit end face part to deflect the light emission direction from the light exit end face part, and the light incident end face part and the light exit end face part Four side end surface portions including a pair of inclined surfaces, a top portion formed in a protruding state on the pair of inclined surfaces, and extending in parallel with the light emitting end surface portion, and the light with the top portion as a boundary. A light guide block including a plurality of prism bodies each having a first inclined surface portion facing the incident end surface portion side and a second inclined surface portion on the opposite side, and deflecting the light traveling direction;
A linear light source facing the light incident end face of the light guide block and extending parallel to the top of the prism body,
The light source and a reflector surrounding the light incident end face, and the distance from the light exit end face of the light guide block to the light source is in a direction perpendicular to the light exit end face. A flat illumination device characterized by being set larger than the thickness.   The light deflecting element of the light guide block has a pair of isosceles triangular openings whose bases are parallel to the central axis of curvature of the concave lens surface of the light incident end surface, and are perpendicular to the light emitting end surface. The flat illumination device according to claim 1, wherein the flat illumination device is a triangular pyramid-shaped concave portion having a conical surface and an inclined conical surface including the base.   The flat illumination device according to claim 2, wherein the light deflection element of the light guide block is formed to have a larger occupation ratio toward a central portion side of the light emitting end face portion. A light incident end face part where light is incident, a light emitting end face part which is located on the opposite side of the light incident end face part and has a larger area than the light incident end face part, and from which the light is emitted, and the light emitting end face part A plurality of light deflection elements that are randomly formed to deflect the light emission direction from the light emission end face part, and are positioned between the light incident end face part and the light emission end face part, and a pair of inclined surfaces Including four side end surface portions, a top portion formed in a protruding state on the pair of inclined surfaces, and extending parallel to the light emitting end surface portion, and a first inclined surface facing the light incident end surface portion side with the top portion as a boundary And a plurality of prism bodies that respectively deflect the light traveling direction, and the angle of inclination of the pair of inclined surfaces with respect to the light emitting end surface portion is the light emitting end surface portion A light guide block set larger toward the side,
A linear light source facing the light incident end face of the light guide block and extending parallel to the top of the prism body,
The light source and a reflector surrounding the light incident end face, and the distance from the light exit end face of the light guide block to the light source is in a direction perpendicular to the light exit end face. A flat illumination device characterized by being set larger than the thickness. A light incident end face part where light is incident, a light emitting end face part which is located on the opposite side of the light incident end face part and has a larger area than the light incident end face part, and from which the light is emitted, and the light emitting end face part A plurality of light deflection elements that are randomly formed to deflect the light emission direction from the light emission end face part, and are positioned between the light incident end face part and the light emission end face part, and a pair of inclined surfaces Including four side end surface portions, a top portion formed in a protruding state on the pair of inclined surfaces, and extending parallel to the light emitting end surface portion, and a first inclined surface facing the light incident end surface portion side with the top portion as a boundary And a plurality of prism bodies that deflect the traveling direction of light, respectively, and an angle formed by the light emitting end surface portion and the second slope portion of the prism body is In the opposite direction of the light incident end face and the light exit end face And the light guide blocks set larger the light emission end surface portion side I,
A linear light source facing the light incident end face of the light guide block and extending parallel to the top of the prism body,
The light source and a reflector surrounding the light incident end face, and the distance from the light exit end face of the light guide block to the light source is in a direction perpendicular to the light exit end face. A flat illumination device characterized by being set larger than the thickness.   The ratio of the area of the light deflection element per unit area of the light emitting end surface portion of the light guide block is set to be larger as the distance from the light incident end surface portion is longer. The flat illumination device according to claim 5.   7. The light reflecting cover according to claim 1, further comprising a light reflecting cover that is formed integrally with the reflector and covers the periphery of the light guide block other than the light incident end face part and the light emitting end face part. A flat illumination device according to claim 1. The light guide block further includes at least a pair of connecting end surface portions that are formed between the light emitting end surface portion and the side end surface portions and are respectively perpendicular to the light emitting end surface portion,
At least two of the light guide blocks are integrally connected through these connection end surfaces,
8. The flat illumination device according to claim 7, wherein the light reflecting cover covers the periphery of the integrally connected light guide blocks.   9. The pair of connection end surface portions of the light guide block, one of which has a locking projection, and the other has a locking recess having a shape corresponding to the locking projection. Planar lighting device.   2. The interval between the prism bodies along the facing direction of the light incident end surface portion and the light emitting end surface portion of the light guide block is set to be narrower toward the light emitting end surface portion side. The flat illuminating device according to claim 9.   The height of the top portion of the prism body of the light guide block is set to be higher toward the light emitting end surface along the opposing direction of the light incident end surface and the light emitting end surface. The flat illumination device according to any one of claims 1 to 10.

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