JP2008198460A - Light emitting element and surface illumination device - Google Patents

Abstract

A thin surface illumination device that can uniformly illuminate a large area by using a resin molded member having a small area and that is highly efficient and low in cost is provided.
A light emitting element 32 includes a red light source 38r, a green light source 38g, and a blue light source 38b arranged in a line, and a light guide plate disposed on the surface side thereof. The long light emitting elements are arranged so as to be substantially continuous in the longitudinal direction, and are arranged with a large interval in the width direction. Conical concave portions are densely formed on the surface of the light guide plate, and convex portions having a triangular cross section are densely formed on the back surface (light source side) of the light guide plate, and the light guide plate emits from each light source. The red light, the green light, and the blue light thus generated are confined and mixed, and the light is spread in the width direction and emitted.
[Selection] Figure 5

Description

  The present invention relates to a light emitting element and a surface illumination device. In particular, the surface illumination device of the present invention can be used as a thin and large backlight, and the light emitting element of the present invention can be suitably used for the surface illumination device.

  As a light source of a conventional backlight for a liquid crystal display, a fluorescent tube such as a cold cathode tube (CCFL) is generally used. However, a liquid crystal display using a fluorescent tube has a problem that color reproducibility is low, and there is a possibility that the global environment is contaminated by mercury used in the fluorescent tube.

  For this reason, backlights using light emitting diodes (LEDs) having three types of light emission colors of red, green, and blue, which are the three primary colors of light, have been developed in recent years. In such a backlight, it is necessary to uniformly mix the light emitted from the red, green, and blue light emitting diodes and turn it into white light to irradiate a diffusion plate or the like that becomes the light emitting surface of the backlight. Become.

  However, when the distance between the light emitting diode and the diffusion plate becomes short, the color of each light emitting diode can be seen through. Therefore, when trying to obtain uniform white light, the light emitting diode and the diffusion plate are separated and mixed between them. Therefore, it is difficult to reduce the thickness of the backlight as much as a conventional backlight using a cold cathode tube. In addition, with the widespread use of large-screen liquid crystal televisions and the like, backlights having a large area and a uniform light emitting surface are required. However, as the backlight becomes larger, the color unevenness and luminance unevenness of the backlight are reduced. It becomes difficult to do.

  In order to solve such problems, Japanese Unexamined Patent Application Publication No. 2006-19141 (Patent Document 1) and Japanese Unexamined Patent Application Publication No. 2006-120355 (Patent Document 2) disclose an LED backlight having an improved structure. Yes.

  1 is a plan view of a backlight 11 disclosed in Patent Document 1, FIG. 2A is a cross-sectional view taken along line A1-A1 in FIG. 1, and FIG. 2B is a cross-sectional view taken along line A2-A2 in FIG. . In this backlight 11, recesses 13 are provided in a row at the center of the back surface of the light guide plate 12, and side-emitting red light emitting elements 14 r, green light emitting elements 14 g, and blue light emitting elements 14 b are provided in the respective recesses 13. (For example, refer to cited document 3) are sequentially arranged at intervals. The red light emitting element 14r has a red light emitting LED chip sealed in a sealing resin, and the green light emitting element 14g has a green light emitting LED chip sealed in a sealing resin, and emits blue light. The element 14b is obtained by sealing a blue light emitting LED chip in a sealing resin, and in each case, a recess for totally reflecting the light emitted from the LED chip toward the side surface is formed on the upper surface of the sealing resin. Has been. Further, an uneven prism surface 15 is formed on the back surface of the light guide plate 12.

  In the backlight 11, red light Lr, green light Lg, and blue light Lb emitted from the side surfaces of the red light emitting element 14 r, the green light emitting element 14 g, and the blue light emitting element 14 b enter the light guide plate 12 from the recess 13. The light is totally reflected by the surface of the light guide plate 12 and the concavo-convex prism surface 15 to guide the light in the light guide plate 12. Lights Lr, Lg, and Lb of the respective emission colors that are guided in the light guide plate 12 in this way are mixed by being guided in the light guide plate 12 as shown in FIG. 2 (b), and are also shown in FIG. 2 (a). As shown, the light is guided through the light guide plate 12 and spreads in the width direction, and is emitted from the surface of the light guide plate 12. Thus, the light emitted from the surface of the light guide plate 12 is further uniformly mixed by being diffused by the diffusion sheet 16 disposed thereon, and is emitted upward as white light.

  3 is a plan view of the backlight 21 disclosed in Patent Document 2, and FIG. 4 is a cross-sectional view showing a cross section along line B1-B1 in FIG. 3 and an enlarged view of the B2 portion. The backlight 21 has a relatively large white light emitting element 22 spread in a grid pattern. The white light emitting element 22 (see, for example, cited document 4) is provided with a reflection mirror 25 on the back side of the transparent resin plate 23, and a red light emitting LED chip 24 r and a green light emitting LED chip at the center of the reflection mirror 25. 24g, blue light emitting LED chip 24b is placed close to each other.

  In this backlight 21, red light Lr, green light Lg, and blue light Lb emitted from the LED chips 24r, 24g, and 24b are reflected on the surface of the transparent resin plate 23 and the reflection mirror 25 as shown in FIG. The white light mixed in the transparent resin plate 23 is emitted from the surface of the transparent resin plate 23 by being guided by repeatedly reflecting between the light and the light. Further, the white light emitted from the white light emitting element 22 is further mixed by being diffused by the diffusion sheet 26 disposed in front of the white light emitting element 22, thereby causing the entire backlight 21 to emit white light.

JP 2006-19141 A JP 2006-120355 A JP 2003-8068 A JP 2006-148036 A JP 2006-309981 A JP 2006-313682 A

  In the backlight 11 disclosed in Patent Document 1, the light emitted from the light emitting elements 14r, 14g, and 14b of each emission color is uniformly mixed using a single light guide plate 12, and the light guide plate is spread over a large area. 12 is emitted to the diffusion sheet 16. Therefore, the light guide plate 12 needs to have an area equivalent to the light emitting surface of the backlight 11, and the area occupied by the light guide plate 12 which is a resin molded product is large.

  Even in the backlight 21 disclosed in Patent Document 2, since the white light emitting element 22 is spread over the entire backlight, when the transparent resin plate 23 used for the white light emitting element 22 is combined, the light emission of the backlight 21 as a whole is also performed. The area is equivalent to the surface, and the area occupied by the transparent resin plate 23 is increased.

  Therefore, in the backlight 11 disclosed in Patent Document 1 and the backlight 21 disclosed in Patent Document 2, the weights of the backlights 11 and 21 are heavy due to the light guide plate 12 and the transparent resin plate 23 of the white light emitting element. There was a problem. Further, since the light guide plate 12 and the transparent resin plate 23 are made of a material having excellent light resistance to (near) ultraviolet light emitted from the LED chip and heat resistance to heat, the cost of the backlight member is high. In general, the cost of the light guide plate and the transparent resin plate accounts for about 10% of the cost of the backlight.

  Further, in the backlight 11 disclosed in Patent Document 1, in order to improve the color mixing property of red, green, and blue light emitted from the light emitting elements 14r, 14g, and 14b, the light generated by the LED chip is used for each light emitting element. Since the light is emitted from the side surfaces of 14r, 14g, and 14b, as shown in FIG. 2B, the light emitted from the light emitting element is absorbed by the adjacent light emitting element or exits from the light emitting element and enters the light guide plate 12 The light that guided the light is absorbed again by the light emitting element, resulting in a loss.

  Also in the backlight 21 disclosed in Patent Document 2, since the LED chips 24r, 24g, and 24b of each color are densely arranged in the white light emitting element 22, as shown in B2 part of FIG. The light emitted from the side surface was absorbed by the adjacent LED chip, resulting in a loss.

  As a result, both the backlight 11 disclosed in Patent Document 1 and the backlight 21 disclosed in Patent Document 2 have deteriorated the light emission efficiency of the backlight 11 by about 10 to 20%.

  In order to improve the brightness of the backlight, a polarizing sheet or a prism sheet may be provided on the surface of the diffusion sheet. In that case, about 50% of the light transmitted through the diffusion sheet is reflected by the polarizing sheet or the like. Return to the light source. In the case of such a structure, in the backlight 11 disclosed in the cited document 1, since the light guide plate 12 exists on the entire surface, all the light reflected and returned by the polarizing sheet is re-entered in the light guide plate 12. It enters and propagates in the light guide plate 12. Also in the case of the backlight 21 of the cited document 2, since the white light emitting elements 22 are spread over the entire surface, the light reflected by the polarizing sheet and returned is captured by the white light emitting elements 22. Therefore, in any of the backlights 11 and 21, the light loss is increased by about 10 to 20% in comparison with the propagation in the air without the resin molding member such as the light guide plate like the backlight using the cold cathode tube. The light utilization efficiency of the backlight was getting worse.

  Further, in the backlight disclosed in the cited document 2, since the white light emitting elements are spread, the required number of the light emitting elements is increased and the cost is increased.

  Patent Document 5 discloses a configuration in which a light guide plate is opposed to a light source and a deflecting portion such as a Fresnel lens shape is provided for spreading light emitted from the light source in the width direction. Further, Patent Document 6 discloses a light source plate that is opposed to a light source and provided with a deflecting portion having a concave groove shape for spreading light emitted from the light source in the width direction. With these structures, when the positional relationship between the deflecting unit and the light source is deviated, a desired orientation cannot be obtained, so that assembly accuracy is required. In addition, since such a light guide plate does not function to sufficiently mix red, green, and blue light, a sufficient space for color mixture must be secured between the light guide plate and the diffusion plate, The backlight becomes thicker.

  In addition, even when white light emitting LEDs are used in each of the above backlights, there is still a problem as described above because the light emitted from each LED must be uniformed to prevent uneven brightness.

  The present invention has been made in view of such technical problems, and the object of the present invention is to uniformly illuminate a large area using a resin molded member having a small area, The present invention relates to an efficient and low-cost thin surface lighting device. Moreover, it is providing the light emitting element suitable for such a surface light source device.

  In the light emitting device of the present invention, a plurality of light sources are arranged along the longitudinal direction, and a light guide plate is disposed so as to cover all the light sources so as to face the light emitting direction of each light source. A light-emitting element having a long shape, wherein the light guide plate refracts light incident from the light source on a surface facing the light source so that directivity characteristics spread on the short side of the light-emitting element, A first optical surface for totally reflecting the light reflected by the opposite surface, and reflecting a part of the light incident from the light source on a surface opposite to the surface facing the light source; It is characterized by having a second optical surface that emits light with wide directivity toward the short side of the light emitting element by transmitting the remaining light.

  The light guide plate in the light emitting device of the present invention refracts light incident from the light source on the surface facing the light source so that the directional characteristics spread on the short side of the light emitting device, and reflects the light on the opposite surface. A first optical surface for totally reflecting the reflected light and reflecting a part of the light incident from the light source on the surface opposite to the surface facing the light source and transmitting the remaining light. Since it has the 2nd optical surface which radiate | emits the light which the directional characteristic spread to the transversal direction side of a light emitting element, the light radiate | emitted from each light source is guided in a light guide plate, The light from each light source can be uniformly dispersed by guiding light by repeating reflection between the opposite side surfaces. Furthermore, in the light-emitting element of the present invention, the light guide plate can widen the directivity characteristic of the light emitted from the light-emitting element toward the short side of the light-emitting element, so that the light-emitting surface can be widened. Therefore, a large area can be illuminated by a small number of light emitting elements.

  In an embodiment of the light emitting element of the present invention, the first optical surface of the light guide plate has a triangular columnar convex pattern with a slope in the short direction of the light guide plate along the short direction of the light guide plate. Arranged. According to this embodiment, the convex pattern can also have a function of spreading the light incident from each light source in the lateral direction of the light emitting element.

  In another embodiment of the light-emitting element of the present invention, the first optical surface of the light guide plate has a cone-shaped convex pattern in which a slope is located in the short side direction and the long side direction of the light guide plate. They are arranged along the hand direction and the longitudinal direction. According to this embodiment, the light incident from each light source can be spread in the short side direction or the long side direction of the light emitting element by the convex pattern. Therefore, even when there is a relatively large gap between the light emitting elements in the longitudinal direction of the light emitting element, it is possible to prevent the luminance from decreasing at the gap portion in the longitudinal direction.

  In still another embodiment of the light-emitting element of the present invention, the first optical surface of the light guide plate is a cone-shaped convex pattern in which a slope is located in an oblique direction with respect to the short side direction and the long side direction of the light guide plate. Are arranged on a light guide plate. According to this embodiment, the light incident from each light source can be spread in the oblique direction of the light emitting element by the convex pattern, and the luminance in the diagonal direction of the light emitting element can be improved.

  In another embodiment of the light emitting device of the present invention, the cross-sectional shape of the convex pattern in the short direction of the light guide plate is asymmetric, and the one-side apex angle on the side farthest from the light source closest to the convex pattern in the cross-section It is made larger than the one-side apex angle on the side closest to the light source closest to the convex pattern. According to this embodiment, the light emitted from the light source and incident on the convex pattern can be hardly reflected by the convex pattern a plurality of times, so that the light emitted from the light guide plate by reflecting the convex pattern a plurality of times It is possible to prevent the emission angle to be perpendicular to the direction from being reduced, and to widen the directivity characteristic of the light emitted from the light guide plate in the short direction of the light guide plate.

  In yet another embodiment of the light emitting device of the present invention, the one-side apex angle on the side farthest from the light source closest to the convex pattern in the cross section gradually increases as the convex pattern becomes farther from the light source. . According to this embodiment, the light emitted from the light source and incident on the convex pattern can be hardly reflected by the convex pattern a plurality of times. In addition, the convex pattern far from the light source is more likely to be reflected multiple times within the convex pattern, but as the distance from the light source is increased, the one-side apex angle on the side farther from the light source of the convex pattern is increased. It becomes difficult to reflect once. Therefore, the light emitted from the light guide plate can be more effectively prevented from being reduced by the light reflected from the convex pattern a plurality of times so that the light emitted from the light guide plate becomes smaller in the direction perpendicular to the light guide plate. The directivity characteristic in the short direction of the light guide plate can be widened.

  In another embodiment of the light emitting device of the present invention, the height of the convex pattern gradually decreases as the distance from the light source closest to the convex pattern increases. The convex pattern far from the light source is more likely to be reflected a plurality of times within the convex pattern. On the other hand, if the height of the convex pattern is reduced, the light is less likely to be reflected a plurality of times within the convex pattern. According to this embodiment, since the height of the convex pattern decreases as the distance from the light source increases, even a convex pattern far from the light source is less likely to be reflected a plurality of times. Therefore, it is possible to prevent the light emitted from the light guide plate from being reflected in the direction perpendicular to the light guide plate by reflecting the convex pattern a plurality of times, and to guide the light emitted from the light guide plate. The directivity in the short direction of the plate can be widened.

  In still another embodiment of the light-emitting element of the present invention, the convex pattern is parallel to the apex angle of the convex pattern in the cross section of the convex pattern parallel to the short direction of the light guide plate and to the longitudinal direction of the light guide plate. The apex angle of the convex pattern in the cross section is different. According to this embodiment, since the apex angle of the convex pattern in the longitudinal direction of the light guide plate and the apex angle of the convex pattern in the short direction of the light guide plate can be set separately, the light emitted from the light emitting element The spread in the short direction and the spread in the longitudinal direction can be arbitrarily set.

  Still another embodiment of the light emitting device according to the present invention is such that the second optical surface of the light guide plate is a conical recess in which the second optical surface of the light guide plate is recessed on the surface opposite to the surface facing the light source. It is composed of patterns. According to this embodiment, the light can be spread in the short direction of the light guide plate by refracting the light emitted from the light guide plate with the concave pattern.

  Still another embodiment of the light-emitting element of the present invention includes an apex angle of the concave pattern in a cross section of the concave pattern parallel to the short direction of the light guide plate and the concave pattern parallel to the longitudinal direction of the light guide plate. The vertical angle of the concave pattern in the cross section is different. According to this embodiment, since the apex angle of the concave pattern in the longitudinal direction of the light guide plate and the apex angle of the concave pattern in the short direction of the light guide plate can be set separately, the light emitted from the light emitting element The spread in the short direction and the spread in the longitudinal direction can be arbitrarily set.

  In another embodiment of the light emitting device of the present invention, the second optical surface of the light guide plate is provided with a diffusion region on the surface opposite to the surface facing the light source of the light guide plate. According to this embodiment, the light can be spread in the short direction of the light guide plate by diffusing the light emitted from the light guide plate in the diffusion region.

  In still another embodiment of the light emitting device of the present invention, the light sources are arranged in a line along the longitudinal direction of the light emitting device. According to this embodiment, since the distance between the light sources can be increased, the light emitted from the light sources is hardly absorbed by the adjacent light sources, and the efficiency of the light emitting element is improved.

  In still another embodiment of the light emitting device of the present invention, the plurality of light sources are a plurality of types of light sources having different emission colors. In the case of such an embodiment, light of different colors emitted from each light source is efficiently and uniformly mixed by the light guide plate. Therefore, a large space for color mixing is not required in front of the light guide plate, and the surface illumination device can be thinned.

  In still another embodiment of the light emitting device of the present invention, the light source includes a red light source, a green light source, and a blue light source. According to this embodiment, since the three primary colors are used as the emission colors of the respective light sources, the color reproducibility of the surface illumination device is further improved.

  In still another embodiment of the light emitting device of the present invention, the light emission colors of the light sources arranged at both ends are different. According to this embodiment, when a plurality of light emitting elements are arranged side by side along the longitudinal direction, light sources having the same emission color are not adjacent to each other between the light emitting elements arranged adjacently in the longitudinal direction. The color mixing property can be improved.

  The light source in yet another embodiment of the light emitting device of the present invention may include a white light source among light sources having different emission colors. According to this embodiment, it is possible to increase the luminance of the light emitting element and reduce the color variation of the light emission color.

  In still another embodiment of the light emitting device of the present invention, each light source is housed in a package, an LED chip is mounted in a recess provided in the package, and the sealing resin is potted in the recess. The LED chip is sealed inside. According to this embodiment, since the lens shape can be formed on the surface of the sealing resin by the surface tension of the sealing resin potted in the recess, the cost can be reduced compared to using a separate lens.

  In still another embodiment of the light emitting device of the present invention, each light source is housed in a package, a step portion for supporting an edge of the light guide plate is provided on a side surface of the package, and the step of the light guide plate is provided. The convex pattern is not formed in the region supported by the portion. According to this embodiment, the light guide plate can be stabilized by supporting the light guide plate at the stepped portion. In addition, since the region supported by the step portion of the light guide plate has a flat surface without providing a convex pattern, the fixing accuracy of the light guide plate is improved and the position of the light guide plate is more stable. Furthermore, if the light guide plate is provided with a flat surface, the light guide plate formed at the time of forming the light guide plate can be used as a protruding portion for protruding by an eject pin.

  The surface illumination device according to the present invention is a light emitting device according to the present invention, which is arranged at a relatively small interval in the longitudinal direction and at a relatively large interval in the short direction. In such a surface illumination device, the light emitted from the light emitting elements is greatly spread in the short direction of the light emitting elements, and therefore, between the adjacent light emitting elements in the short direction of the light emitting elements arranged at relatively large intervals. A decrease in luminance at the gap portion can be suppressed, and uniform luminance can be obtained throughout the surface illumination device. In addition, by using the light-emitting element of the present invention, it is light and thin, has a large area, high light utilization efficiency, and uniform brightness on the light-emitting surface (and, if a light source having a different light emission color is used, color It is possible to manufacture a surface illumination device for a backlight or the like that can be manufactured at a low cost.

  In one embodiment of the surface illumination device of the present invention, the light source is a plurality of types of light sources having different emission colors, and the light emitting elements are arranged such that the light sources of the respective emission colors are equally spaced in the longitudinal direction. Has been placed. According to such an embodiment, since the light sources of the respective emission colors are arranged at equal intervals, the color mixing property between the light emitting elements is improved, and uneven color is less likely to occur.

  In another embodiment of the surface illumination device of the present invention, a reflecting member is disposed in the gap between the light emitting elements or behind the gap. According to this embodiment, the light leaked from the light guide plate or the like to the back side can be reflected forward, and the light utilization efficiency can be further improved.

  In still another embodiment of the surface illumination device of the present invention, a diffusion sheet is disposed in front of the light emitting element. According to this embodiment, since the light emitted from the light emitting element can be diffused by the diffusion sheet and emitted forward, the color mixing property of the light can be further improved.

  The means for solving the above-described problems in the present invention has a feature in which the above-described constituent elements are appropriately combined, and the present invention enables many variations by combining such constituent elements. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 5 is a plan view showing the surface illumination device 31 according to the first embodiment of the present invention. 6 is a cross-sectional view taken along line C1-C1 in FIG. 5, and FIG. 7 is a cross-sectional view taken along line C2-C2 in FIG. In the surface illumination device 31, strip-like light emitting elements 32 are arranged almost continuously along the longitudinal direction, and the light emitting elements 32 are several times the width of the light emitting elements 32 in the short direction (width direction) of the light emitting elements 32. Are spaced sparsely, and a considerable distance is also provided between the light emitting element 32 located at the end in the short direction and the edge of the surface illumination device 31. The entire surface of the surface illumination device 31 is covered with a plate-like transparent diffusing member 33, and a space 34 for mixing light emitted from the light emitting element 32 between the light emitting element 32 and the diffusing member 33. Is formed. Further, on the back surface side of the light emitting element 32, a plate-like reflecting member 35 is provided on the entire back surface of the surface illumination device 31 or so as to fill a gap between the light emitting elements 32.

  As the reflecting member 35, a member having a high light reflectance such as a white resin plate, a white resin sheet, or a metal plate is used. As the diffusing member 33, a transparent plate having a fine diffusion pattern formed on its surface, a transparent plate having a fine diffusing agent dispersed, or the like is used. Further, on the surface side of the diffusing member 33, a prism sheet or a polarizing sheet for improving luminance may be provided as necessary (details will be described later).

  6 and 7, the light emitting element 32 includes a red light source 38r in which a red light emitting LED chip 36r is sealed with a sealing resin 37, and a green light source in which a green light emitting LED chip 36g is sealed with a sealing resin 37. A blue light source 38 b in which a light source 38 g and a blue light emitting LED chip 36 b are sealed with a sealing resin 37 is arranged in a line on a substrate 39. The LED chips 36r, 36g, 36b are arranged with an interval several times the size of the light source. A light guide plate 40, which is a resin molded member, is disposed on the light emitting side of the light emitting element 32 so as to cover the LED chips 36r, 36g, and 36b.

  FIG. 8A is a perspective view from the front surface side showing a part of the light guide plate 40 in an enlarged manner, and FIG. 8B is a perspective view from the back surface side showing a part of the light guide plate 40 in an enlarged manner. is there. 9A and 9B are enlarged cross-sectional views showing a part of the shape of the light guide plate 40. FIG. 9A shows a cross section perpendicular to the short direction, and FIG. It represents a cross section perpendicular to the direction. Hereinafter, the longitudinal direction of the light emitting element 32, that is, the direction in which the LED chips 36r, 36g, and 36b are arranged most densely is referred to as the X direction, and the thickness direction of the light guide plate 40 is referred to as the Z direction. The width direction, that is, the direction in which the light emitting elements 32 are sparsely arranged perpendicular to the X direction and the Z direction is referred to as a Y direction.

  The light guide plate 40 is a resin molded member formed into a plate shape with a transparent and high refractive index resin such as polycarbonate resin (PC) or polymethyl methacrylate (PMMA). As shown in FIG. 8A, fine conical concave portions 41 are densely arranged on the entire surface (second optical surface) of the light guide plate 40, and the back surface (first optical surface) of the light guide plate 40. As shown in FIG. 8B, convex portions 42 in the form of prisms having a fine triangular cross section are formed densely on the entire optical surface 1. The conical recesses 41 may be regularly arranged or randomly arranged. As shown in FIGS. 9A and 9B, the convex portions 42 having a triangular cross section are arranged in the short direction (Y direction) of the light guide plate 40, and the long direction (X direction) of the light guide plate 40. Have a uniform cross section.

  10 and 11 are explanatory views of the operation of the light guide plate 40. FIG. 10 shows the behavior of light in a cross section parallel to the ZX plane, and FIG. 11 shows the behavior of light in a cross section parallel to the ZY plane. Yes. Although only the green light Lg emitted from the green light source 38g is shown in FIG. 11, the behavior of the red light Lr emitted from the red light source 38r and the blue light Lb emitted from the blue light source 38b is also similar to that of the green light Lg. Same as the case.

  First, the behavior of light in a cross section parallel to the ZX plane will be described. As shown in FIG. 10, the red light Lr, the green light Lg, and the blue light Lb emitted from the light sources 38r, 38g, and 38b are incident on the light guide plate 40 from the back surface of the light guide plate 40. The light is guided through the light guide plate 40 while repeating total reflection between the front surface and the back surface, and part of the light incident on the conical recess 41 is refracted by the conical recess 41 and emitted to the outside. The

  As described above, the red light Lr of the red light source 38r, the green light Lg of the green light source 38g, and the blue light Lb of the blue light source 38b emitted from different places are guided through the light guide plate 40 and are transmitted through the light guide plate 40. The light spreads almost entirely and is uniformly mixed with each other and emitted from the surface of the light guide plate 40. For example, in FIG. 10, the red light Lr and the green light Lg that have been guided through the light guide plate 40 are also emitted just above the blue light source 38b, and these lights are mixed. The white light that is uniformly mixed and emitted from the light guide plate 40 is further mixed in the space 34 between the diffusion member 33 and irradiates the diffusion member 33, thereby causing the diffusion member 33 to emit white light uniformly.

  For this reason, the adjacent light sources 38r, 38g, and 38b can be arranged apart from each other to some extent. For example, the arrangement pitch of the LED chips 36r, 36g, and 36b can be arranged to be about several mm. Like the green light Lg shown, light emitted from the light sources 38r, 38g, and 38b becomes difficult to enter the adjacent light sources 38r, 38g, and 38b, and absorption and loss of the emitted light can be reduced. Further, by emitting the light of each of the light sources 38r, 38g, and 38b to the front with the lens shape of the sealing resin 37, the reflection cup, or the like, the absorption and loss of light can be further reduced. And the light utilization efficiency of the surface illuminating device 31 can be improved by reducing light absorption and loss.

  For example, the length of the light guide plate 40 in the X direction is 60 mm, the width in the Y direction is 10 mm, the thickness in the Z direction is 2 mm, the distance between the centers of the light sources 38r, 38b, 38b is 5 mm, and the conical recess 41 When the apex angle β is 150 ° and the distance between the light sources 38r, 38g, and 38b and the diffusing member 33 is 20 mm, compared to the case where the light sources 38r, 38g, and 38b are arranged close to each other, Utilization efficiency improved by about 15%.

  Next, the behavior of light in a cross section perpendicular to the longitudinal direction of the light guide plate 40 will be described. As shown in FIG. 11, when viewed from the X direction, the light emitted from each of the light sources 38r, 38g, and 38b is refracted by passing through the convex portion 42 formed on the back surface of the light guide plate 40. Furthermore, the light refracted when passing through the conical recess 41 and exiting from the light guide plate 40, and the light emitted at an exit angle of θs with respect to the central axes of the light sources 38r, 38g, and 38b, By passing through the light guide plate 40, the light is emitted at an emission angle θt larger than θs. Moreover, the light emitted from the light guide plate 40 is sufficiently mixed in the light guide plate 40 as described above to become white light. Therefore, even in the ZY plane, the light is sufficiently mixed to become white light, and the white light is spread in the width direction of the light emitting element 32 by the optical action of the convex section 42 and the conical concave section 41. . As a result, the light is spread in the width direction in which the light emitting elements 32 are sparsely arranged by the action of the light guide plate 40, and the light is mixed in the space 34, so that the light emitting elements 32 and the light emitting elements in the width direction of the light emitting elements 32 are mixed. Even in a region intermediate to 32, the mixed white light is irradiated to the diffusing member 33 with a sufficient amount of light.

  For example, the length of the light guide plate 40 in the X direction is 60 mm, the width in the Y direction is 10 mm, the thickness in the Z direction is 2 mm, the apex angle α of the convex portion 42 having a triangular cross section is 60 °, and the conical concave portion 41. When the apex angle β is 150 ° and the distance between the light sources 38r, 38g, 38b and the diffusing member 33 is 20 mm, the position of the diffusing member 33 is uniform with a width 6 times the width of the light guide plate 40. An irradiated area was obtained. Therefore, in this case, in the width direction of the light emitting elements 32, the distance between the light emitting elements 32 can be about 6 times that of the light guide plate 40.

  It should be noted that most of the light leaking from the back surface of the light guide plate 40 is reflected by the reflecting member 35, is incident on the light guide plate 40 again, and is reused.

  In the surface illumination device 31 of the present invention, since the light emitting elements 32 are arranged at a large distance in the width direction, the light guide plate that is a resin molded part with respect to the light emitting area of the surface illumination device 31. The area of 40 can be reduced, and the surface illumination device 31 can be reduced in weight and the member cost can be reduced. Furthermore, the number of light emitting elements required can be reduced by arranging the light emitting elements with a gap therebetween, and the cost of the surface illumination device 31 can be further reduced.

  In addition, by using the light emitting element including the light guide plate 40 having the structure as described above, the light use efficiency of the light emitting element can be increased and light can be emitted uniformly over a wide area compared to the area of the light emitting element. Therefore, even though the light emitting elements 32 are arranged at a large distance in the width direction, the surface illumination device 31 is unlikely to be dark even in the region between the light emitting elements 32 in the width direction, and the luminance is uniform and uniform. Can emit light. Further, since the light can be sufficiently mixed by the light guide plate 40, the space between the light guide plate 40 and the diffusion member 33 can be narrowed, and the surface illumination device 31 can be thinned.

  Further, by arranging the light emitting elements 32 at a large distance in the width direction, the light emitted from each light source enters the adjacent light emitting elements in the width direction and is not easily absorbed by the light sources. Further, since the light guide plate 40 of the light emitting element 32 is arranged so as to face the surface side of each of the light sources 38r, 38g, 38b, the light emitted from the light source also reenters the light source in the longitudinal direction of the light emitting element. It becomes difficult to be absorbed. As a result, it is possible to suppress a decrease in light emission efficiency of the surface illumination device 31 due to reabsorption by the light source.

  In addition, since the concave portions 41 and the convex portions 42 are formed on almost the entire front and back surfaces of the light guide plate 40, even if the positions of the light sources 38r, 38g, and 38b and the light guide plate 40 are slightly shifted, orientation variation hardly occurs. .

  When the surface illumination device 31 according to Embodiment 1 of the present invention and the backlight according to the conventional example of FIG. 3 are compared with the same brightness, thickness, size, and uniformity of brightness, the following results are obtained. . First, the ratio of the area of the resin molded member (the diffusion member 33 of the present invention and the transparent resin plate 23 of the conventional example) to the light emitting surface is reduced to 1/6 of the conventional example in the present invention, and the thickness of the resin molded member is also reduced. Can be reduced to ½ of the conventional example. Therefore, according to the present invention, the volume of the resin molded member is 1/12 compared to the conventional example, and the cost of the resin molded member is also 1/12, and the cost of the surface illumination device of the present invention is the same as that of the conventional backlight. The cost could be reduced by about 10%.

  Further, the light loss between the adjacent light emitting elements was reduced by 15% in the surface illumination device of the present invention compared to the conventional backlight. Even in a general backlight optical sheet configuration (see FIG. 14), the light utilization efficiency is improved by 20% in the present invention compared to the conventional example. Therefore, according to the present invention, the required number of LED chips can be reduced by about 40%, and as a result, the cost of the surface illumination device of the present invention can be reduced by about 10% than the cost of the conventional backlight. did it.

  As described above, according to the present invention, when the cost reduction by the resin molded member is approximately 10% and the cost reduction by the LED chip is approximately 10%, the present invention enables a total reduction of approximately 20%.

  Moreover, according to this invention, since the volume of the resin molding member becomes 1/12 as mentioned above, the surface illuminating device 31 can be reduced in weight. In addition, since the thickness can be reduced to about half compared to the conventional one in which color is mixed in the space without using a resin molded member, according to the present invention, the surface illumination device 31 can be reduced in weight and thickness.

  FIG. 12 shows a luminance distribution of a conventional example in which three white light emitting elements 22 (9 LED chips) used in the backlight shown in FIG. 3 are arranged, and a book in which nine LED chips are arranged in a line. It is the figure showing the result of having measured the luminance distribution of the light emitting element of an Example. In FIG. 12, the white light emitting element in the conventional example and the light emitting element in the example are both represented by broken lines, and the positions of the respective LED chips are represented by arrows. According to this measurement result, in the case of the embodiment of the present invention, it can be seen that the luminance of the central portion is improved by 40% as compared with the conventional example, and the uniformity of the luminance is comparable. On the contrary, if the luminance is made equal, the surface illumination device 31 of the present invention can reduce power consumption by 40% compared to the conventional example.

  In the illustrated example shown in FIG. 7, since the side surface of the light emitting element 32 is opened, the red light Lr, the green light Lg, and the blue light Lb emitted from the light sources 38r, 38g, and 38b from the light emitting element 32 in the width direction. There is a risk of leaking directly to the front and exiting forward without being uniformly mixed. Thus, when the light emitted from the red light source 38r, the green light source 38g, and the blue light source 38b leaks directly to the outside without passing through the light guide plate 40, the light emitting surface of the surface illumination device 31 appears to be colored. In order to prevent such a problem, as shown in FIG. 13, a space between the side surface of the substrate 39 and the side surface of the light guide plate 40 may be covered with a reflection plate 43.

(Embodiment 2)
FIG. 14 is a schematic cross-sectional view showing the structure of a surface illumination device 31 according to Embodiment 2 of the present invention. In this embodiment, a prism sheet 44 and a polarizing sheet 45 are arranged on the surface side of the diffusing member 33. This is a general configuration when the surface illumination device 31 is used as a backlight of a liquid crystal display panel. The light emitted from each of the light sources 38r, 38g, and 38b is diffused by the light guide plate 40 and the diffusion member 33, and then condensed in the front direction by the prism pattern of the prism sheet 44 when passing through the prism sheet 44. The front luminance of the lighting device 31 is improved. Light L condensed by the prism sheet 44 (light mixed with red light Lr, green light Lg, and blue light Lb) is linearly polarized light in a polarization direction necessary for the liquid crystal display panel disposed in front of the surface illumination device 31. Only L ₊ transmits the polarizing sheet 45.

The polarizing sheet 45 used here is a transflective polarizing sheet having a characteristic of transmitting linearly polarized light having a certain polarization direction and reflecting linearly polarized light having a polarization direction orthogonal thereto. Therefore, the linearly polarized light L ₋ having a polarization direction orthogonal to the polarization direction necessary for the liquid crystal display panel is reflected and returned by the polarization sheet 45, passes through the prism sheet 44 and the diffusion member 33, reaches the reflection member 35, and is reflected by the reflection member. 35 is diffusely reflected. The polarization direction of the light diffusely reflected by the reflecting member 35 is random, and this diffusely reflected light passes through the diffusing member 33 and the prism sheet 44 again and enters the polarizing sheet 45. Of the light incident on the polarizing sheet 45, only the linearly polarized light L _{+ in the} polarization direction necessary for the liquid crystal display panel is transmitted through the polarizing sheet 45, and the linearly polarized light L ₋ in the polarization direction orthogonal thereto is reflected by the polarizing sheet 45 and reflected. Return to the member 35 side. By repeating such light behavior, almost all of the light emitted from each of the light sources 38r, 38g, and 38b is converted into light having a polarization direction that can be used in the liquid crystal display panel to illuminate the liquid crystal display panel. Therefore, the light use efficiency can be greatly improved, and the screen brightness of the liquid crystal display panel can be improved.

  A part of the light reflected by the polarizing sheet 45 and returning to the reflecting member 35 side is not reflected by the reflecting member 35, but is absorbed by the light guide plate 40 and each of the light sources 38r, 38g, and 38b to be lost. However, in the surface illumination device 31 of the present invention, since the installation area of the light emitting element 32 is very small compared to the area of the entire surface illumination device 31, most of the light returning to the reflection member 35 side is polarized with the reflection member 35. Reflected between the sheets 45 and reused.

For example, the length of the light guide plate 40 in the X direction is 60 mm, the width in the Y direction is 10 mm, the thickness in the Z direction is 2 mm, and the area of the surface illumination device 31 is about six times that of the light guide plate 40 (that is, about 3600 mm). ² ), the light utilization efficiency was improved by about 20% compared to the conventional example (having a prism sheet and a polarizing sheet) in which white light emitting elements 22 as shown in FIG. 3 were laid.

(Embodiments 3, 4, 5)
Next, a method for designing the convex portion 42 provided on the light guide plate 40 and the third, fourth, and fifth embodiments will be described. FIG. 15 illustrates the apex angle α of the convex portion 42 having a triangular cross section provided on the back surface of the light guide plate 40. When the apex angle α of the convex portion 42 is increased and becomes obtuse, as in the convex portion 42 indicated by a one-dot chain line in FIG. 15, light (indicated by an arrow) emitted from the upper surface of the light guide plate 40 is Z direction. The angle made with respect to becomes smaller. On the other hand, when the apex angle α of the convex portion 42 is small and acute, as in the convex portion 42 indicated by a solid line in FIG. 15, the angle made by the light incident on the convex portion 42 with respect to the Z direction increases. However, if the apex angle α of the convex portion 42 becomes too small, as in the convex portion 42 shown by a broken line in FIG. 15, the light incident on the light guide plate 40 is totally reflected by the convex portion 42 a plurality of times, and the light guide plate 40 The exit angle formed by the light exiting from the Z direction is rather small.

  Accordingly, as shown in FIG. 16, the convex portion 42 having a triangular cross section has an apex angle α that is reduced to an acute angle, while the light incident on the convex portion 42 having the triangular cross section is a convex portion having a triangular cross section. It is desirable to reduce the height H of the convex portion 42 having a triangular cross section so as not to be reflected a plurality of times within the surface 42.

  FIG. 17 is a schematic view showing a part of a cross section of the light guide plate 40 used in the surface illumination device according to Embodiment 3 of the present invention. In the third embodiment, as shown in FIG. 17, the apex angle α (= α1 + α2) is reduced to an acute angle, and the cross-section of the convex portion 42 having a triangular cross section is asymmetrical, and the light sources 38r, 38g, and 38b. The side angle (one side apex angle) α2 on the side farther from each of the light sources 38r, 38g, 38b is made larger than the angle (one side apex angle) α1 closer to.

  According to the third embodiment, since the one-side apex angle α1 on the side close to the light sources 38r, 38g, and 38b is reduced, the light incident on the convex portion 42 from the light source side can be greatly expanded in the width direction, and the light source 38r. Since the one-side apex angle α2 on the side far from 38g, 38b is increased, the light largely bent by the convex portion 42 can be prevented from being reflected on the side surface far from the light sources 38r, 38g, 38b. The light can be greatly expanded in the width direction.

  When the apex angles α of the convex portions 42 arranged in the Y direction are the same, as shown in FIG. 18, when the light emission angle θs from the light sources 38r, 38g, and 38b increases, the light guide plate 40 The emission angle θt of the light emitted from the upper surface of the light increases, and the light can be greatly spread in the width direction of the light guide plate 40. However, also in this case, when the emission angle θs becomes too large, the light incident on the convex portion 42 is reflected by the convex portion 42 a plurality of times, and on the contrary, the emission angle θt from the upper surface of the light guide plate 40 becomes small.

  Embodiments 4 and 5 solve such problems. FIG. 19 is a schematic view showing a part of a cross section of a light guide plate 40 used in a surface illumination device according to Embodiment 4 of the present invention. In the fourth embodiment, as shown in FIG. 19, the height H of the convex portion 42 having a triangular cross section gradually decreases as the distance from the position immediately above the light sources 38r, 38g, and 38b increases.

  FIG. 20 is a schematic view showing a part of a cross section of the light guide plate 40 used in the surface illumination device according to the fifth embodiment of the present invention. In the fifth embodiment, as shown in FIG. 20, the one-side apex angle α2 of the side surface farther from the light source of the convex section 42 having a triangular cross section gradually increases as the distance from the position immediately above the light sources 38r, 38g, and 38b increases. Yes.

(Embodiment 6)
Next, a design method of the recess 41 provided in the light guide plate 40 and the sixth embodiment will be described. FIG. 21 illustrates the apex angle β of the conical recess 41 provided on the surface of the light guide plate 40. As shown by a one-dot chain line in FIG. 21, when the apex angle β of the conical recess 41 is large and the apex of the recess 41 becomes obtuse, the angle formed by the light emitted from the surface of the light guide plate 40 with the Z direction is small. Become. Further, as indicated by a broken line in FIG. 21, when the apex angle β of the concave portion 41 is small and becomes an acute angle, the angle formed by the light emitted from the concave portion 41 with respect to the Z direction becomes large. However, when the apex angle β of the concave portion 41 becomes too small, the light incident on the light guide plate 40 is totally reflected by the concave portion 41 and is not emitted outside from the light guide plate 40, and is emitted in the width direction of the light guide plate 40. On the other hand, the light is confined in the light guide plate 40 and easily guided, so that the color mixing property is improved.

  Therefore, when it is desired to improve the color mixing by the light guide plate 40, such as when the distance P between the light sources 38r, 38g, 38b shown in FIG. Should be improved. Conversely, when it is desired to spread the light in the width direction, the apex angle β of the recess 41 may be reduced to such an extent that the light is not easily totally reflected by the recess 41.

  FIG. 23 is a schematic view showing the structure of a surface illumination device according to Embodiment 6 of the present invention. As shown in FIG. 23, in the concave portion 41 (indicated by reference numeral 41a in FIG. 23) positioned immediately above each of the light sources 38r, 38g, and 38b, the apex angle β is reduced and light emitted forward from the concave portion 41. In the region away from any of the light sources 38r, 38g, and 38b, the apex angle β of the concave portion 41 (indicated by reference numeral 41b in FIG. 23) is increased so that the light is directed in the front direction. By facilitating the emission, the color mixing property of the surface illumination device can be improved and the luminance distribution can be made uniform.

(Embodiment 7)
Next, different patterns provided on the front and back surfaces of the light guide plate 40 will be described. The pattern provided on the light guide plate 40 is not limited to the conical concave portion 41 and the convex portion 42 having a triangular cross section, and may be a pyramidal concave portion 41 or a convex portion 42. There may be.

  For example, the gap between the light emitting elements 32 in the longitudinal direction of the light emitting element 32 is wide, and the amount of light in the gap is insufficient, and it is desired to increase the amount of light emitted in the longitudinal direction as shown in FIG. In such a case, the embodiment 7 shown in FIG. In the seventh embodiment shown in FIG. 24B, the inclined surface of the convex portion 42 is located in the longitudinal direction (X direction) and the short direction (Y direction) of the light guide plate 40. As for this convex part 42, it is desirable for apex angle (alpha) to be smaller than 180 degrees in any of an X direction and a Y direction. If the convex portion 42 having such a shape is provided, the emitted light L can be spread in the longitudinal direction of the light guide plate 40, so that it is adjacent not only in the width direction of the light emitting element 32 but also in the longitudinal direction of the light emitting element 32. It is also possible to suppress a decrease in luminance in a gap portion between the light emitting elements 32 to be performed.

(Embodiment 8)
Further, in the case where it is desired to further improve the color mixing property in the longitudinal direction of the light guide plate 40, it may be performed as in the eighth embodiment shown in FIG. In the case of the eighth embodiment shown in FIG. 25, the concave portion 41 provided on the surface side of the light guide plate 40 is formed in a pyramid shape so that the apex angle β in the ZY section is larger than the apex angle β in the ZX section. That's fine. According to such a shape, since the total reflection frequency in the ZX cross section becomes larger than the total reflection frequency in the ZY cross section, the color mixing property of light in the X direction is further improved. In order to obtain the same effect, an elliptical conical recess 41 in which the Y-axis direction is the major axis direction and the X-axis direction is the minor axis direction may be provided.

(Embodiment 9)
Further, as shown in FIG. 26, when it is desired to increase the light intensity in the diagonal direction that forms an angle of about 45 ° with respect to the X-axis direction and the Y-axis direction, the embodiment shown in FIGS. 9 should be used. In the ninth embodiment, the concave portions 41 on the front surface are inclined in the X direction and the Y direction, and the convex portions 42 on the back surface are inclined in the diagonal direction. As a result, the apex angle β in the ZX cross section of the recess 41 is smaller than the apex angle β in the cross section in the diagonal direction, so that the light reflection frequency in the ZX cross section is larger than the light reflection frequency in the diagonal direction. Further, since the apex angle α in the ZY cross section of the convex portion 42 is larger than the apex angle α in the cross section in the diagonal direction, the light emission angle in the ZY cross section becomes smaller than the light emission angle in the diagonal direction. Therefore, the color mixing degree of the light in the X direction increases, and the intensity of the light emitted in the diagonal direction increases.

  Note that when a monochromatic light source or a white light source is used, it is not necessary to mix light, so the apex angle β in the ZX section of the recess 41 may be an obtuse angle. However, even in this case, since there is an effect of averaging and improving the variation of each light source, it is desirable that the design be the same as in the case of mixing light even in such a case.

(Embodiment 10)
As shown in FIG. 28A, the tip of the convex portion 42 having a triangular cross section may be rounded. For example, when the cross section of the convex portion 42 has an acute angle, light is reflected by the convex portion 42 a plurality of times as indicated by a broken line, but if the tip of the convex portion 42 is rounded, It is possible to prevent the light from being reflected by the convex portion 42 a plurality of times, and to increase the light emission angle. Further, as shown in FIG. 28 (b), the tip end portion of the convex portion 42 having an acute angle as a whole may be obtuse, and as shown in FIG. 28 (c), the entire convex portion 42 is formed by a curved surface. May be. Thus, by making the tip shape of the convex portion 42 a rounded surface, a polygonal shape, a curved surface shape or the like, it is possible to give diversity to the light control method and design. Further, in the assembly process or the like, the tip of the convex portion 42 is not easily crushed.

  Further, as shown in FIG. 29A, the tip of the conical recess 41 may be rounded. For example, when the cross section of the concave portion 41 has an acute angle, light is refracted by the concave portion 41 and travels in the vertical direction as shown by a broken line, but if the tip of the concave portion 41 is rounded, It becomes easy to totally reflect the light by the recess 41, and the color mixing property can be improved. Further, as shown in FIG. 29 (b), the tip end portion of the concave portion 41 having an acute angle as a whole may be obtuse, and as shown in FIG. 29 (c), the entire concave portion 41 is formed by a curved surface. Also good. As described above, the light control method and design can be varied by making the tip shape of the concave portion 41 a rounded surface, a polygon, or a curved surface. In addition, the recess 41 in the light guide plate 40 can be easily formed.

(Embodiment 11)
FIG. 30 is a cross-sectional view showing the structure of the light emitting device 32 according to Embodiment 11 of the present invention. In this light guide plate 40, triangular prism-shaped convex portions 42 having a uniform cross section along the X direction are formed on the back surface of the light guide plate 40, and on the surface (second optical surface) of the light guide plate 40. Are provided with dispersed diffusion regions 46 instead of the recesses 41. As the diffusion region 46, the surface of the light guide plate 40 may be finely roughened to be roughened, white paint or the like may be dot-printed, or a white sheet may be dispersed and pasted on the surface. According to the light guide plate 40 having such a structure, a part of the light in the light guide plate 40 can be diffused and reflected by the diffusion region 46 to be guided, and the diffusion region 46 on the surface of the light guide plate 40 can be guided. Even in a non-existing region (flat surface), light can be totally reflected and guided. In addition, by diffusing a part of the light in the light guide plate 40 in the diffusion region 46, the light can be emitted in the width direction, and the light guide plate 40 has a region (flat surface) without the diffusion region 46 on the surface. ) But light can be refracted and emitted in the width direction. Of course, also in the eleventh embodiment, the light can be spread in the width direction also by the convex portion 42 having a triangular prism section.

  In the light emitting element 32 of FIG. 30, the diffusion region 46 is provided directly on the surface of the light guide plate 40. However, as shown in FIG. 31, the diffusion region 46 is provided on the back surface of the transparent member 47 such as a transparent resin sheet or a transparent resin plate. And a transparent member 47 having a diffusion region 46 formed on the back surface may be attached to the surface of the light guide plate 40.

  Alternatively, as shown in FIG. 32, a diffusion region 46 is formed on the surface of a transparent member 47 such as a transparent resin sheet or transparent resin plate, and the transparent member 47 having the diffusion region 46 formed on the surface is used as the light guide plate 40. You may affix on the surface.

Embodiment 12
33 (a) and 33 (b) are views showing a light emitting device 32 according to Embodiment 12 of the present invention. FIG. 33 (a) is a schematic plan view showing the position of the convex portion 42, and FIG. It is a DD sectional view taken on the line 33 (a). In the twelfth embodiment, the density (number) of the convex portions 42 is increased above the portion where the LED chips 36r, 36g, and 36b are arranged, and the density of the convex portions 42 is decreased at the edge of the light guide plate 40. . When the directivity characteristics of light emitted from the LED chips 36r, 36g, and 36b, particularly the directivity characteristics in the Y direction, are wide, the convex portions 42 are arranged in this manner, so that the LED chips 36r, 36g, and 36b Light emitted at a wide angle can be emitted from the light emitting element 32 at a wide angle as it is, and the surface illumination device 31 can be uniformly illuminated over a wide range.

  On the contrary, when the amount of light above the portion where the LED chips 36r, 36g, 36b are arranged is insufficient, the density of the convex portions 42 above the portion where the LED chips 36r, 36g, 36b are arranged ( The number of projections 42 may be increased at the edge of the light guide plate 40.

  In the case of the situation described in the twelfth embodiment, the apex angle α of the convex portions 42 may be changed instead of changing the density of the convex portions 42 (see FIG. 20).

(Embodiment 13)
FIG. 34A is a plan view showing a light emitting element 32 according to Embodiment 13 of the present invention, and FIG. 34B is a sectional view showing a section in the light source arrangement direction of Embodiment 13. The thirteenth embodiment represents a case where the numbers of LED chips 36r, 36g, and 36b for each emission color are extremely different. That is, in the example shown in FIGS. 34A and 34B, the number of red light emitting LED chips 36r is half the number of green light emitting LED chips 36g and blue light emitting LED chips 36b (on the other hand, red LEDs). Has twice the amount of light emitted by the green and blue LEDs.) When the number of LED chips 36r, 36g, and 36b for each emission color is extremely different in this way, the LED chip 36r, 36g, and 36b having a smaller number of emission colors (red LED in the illustrated example) is directly above. The density of the recesses 41 is increased, and the density of the recesses 41 immediately above the light emitting color LEDs (blue LEDs, green LEDs) is reduced. By doing so, it is possible to increase the color mixing property by increasing the frequency of total reflection by the concave portions 41 in the LED chips of the light emitting color having a wide interval (low density) arranged side by side.

  In order to obtain the same effect as this, the apex angle β of the concave portion 41 may be changed immediately above each of the LED chips 36r, 36g, and 36b for each emission color. Further, in order to improve the color mixing property between the adjacent light emitting elements 32, the density of the concave portions 41 at the longitudinal ends of the light guide plate 40 may be increased.

  Further, when there is a large assembly variation between the package of the light emitting element 32 and the light guide plate 40, the apex angles, sizes, shapes, etc. of the convex portions 42 and the concave portions 41 are provided with various variations to some extent. The proportions of the concave portions 41 and the convex portions 42 having the above shape may be determined according to the design method as described above. Thereby, even if the angle of the light emitted from the LED chips 36r, 36g, and 36b varies, the light can be emitted at a wide angle or mixed color by any one of the concave portions 41 or the convex portions 42. In addition, the uniformity and color mixing property of the surface illumination device 31 can be further improved by variously combining the above examples.

(Embodiment 14)
When the red light source 38 r, the green light source 38 g, and the blue light source 38 b are inserted into the light emitting element 32, they are arranged densely in the longitudinal direction of the light emitting element 32. In that case, conventionally, in order to improve the color mixing of each light source, it is general to arrange the light sources of the respective emission colors so as to be symmetric with respect to the center. For example, in the conventional light emitting device 28 shown in FIG. 35, the red LED chip 36r is placed at the center, and the green LED chip 36g and the blue LED are sequentially arranged symmetrically on both sides thereof. A chip 36b, a red LED chip 36r, and a green LED chip 36g are arranged. However, when such light emitting elements 28 are arranged side by side in the length direction, the interval between the LED chips of the same color is remarkably different among the respective emission colors. In the case of FIG. 35, between the light emitting elements 28, the distance Sg between the green LED chips 36g is the shortest, the distance Sb between the blue LED chips 36b is the longest, and the distance Sr between the red LED chips 36r is the same. Intermediate spacing. As a result, when such a light emitting element 28 is used, the color mixing property within the light guide plate of each light emitting element 28 is not sufficient, and the color mixing property between the light emitting elements 28 is deteriorated.

  FIG. 36 is a plan view showing an LED chip array of the light emitting elements 32 according to Embodiment 14 of the present invention. In the light emitting element 32 of this embodiment, the same number of red LED chips 36r, green LED chips 36g, and blue LED chips 36b are arranged at a constant pitch so as to repeat the order of the LED chip 36g, LED chip 36r, and LED chip 36b from the end. is doing. Therefore, the LED chips at both ends of the light emitting element 32 have different emission colors. Accordingly, the light emitting elements are arranged such that the distance S between the LED chip 36b located at the right end of the left light emitting element 32 and the LED chip 36g located at the left end of the right light emitting element 32 in FIG. 36 is equal to the arrangement pitch of the LED chips. If the 32 are arranged, the spacing Sg between the green LED chips 36g, the spacing Sb between the blue LED chips 36b, and the spacing Sr between the red LED chips 36r between the light emitting elements 32 become equal. Color mixing between the two is improved.

  Next, when considering the case where the light emitting elements 32 as described above are arranged sparsely in the width direction, FIG. 37 is obtained. In FIG. 37, the light emitting elements 32 are arranged in the same manner in the width direction. However, according to such an arrangement, a row of red LED chips 36r, a row of blue LED chips 36b, and a row of green LED chips 36g. As a result, striped color unevenness occurs on the light emitting surface of the surface illumination device 31.

  In order to eliminate such color unevenness, an asymmetrical light emitting element 32 as shown in FIG. 36 is used, and as shown in FIG. 38, the direction of the light emitting elements 32 is rotated by 180 degrees for every row, and the light emitting elements are arranged every other row. It is sufficient that the directions of 32 are aligned. In the case of FIG. 38, only the rows of red LED chips 36r are generated, but since only red is arranged in a row, striped color unevenness is improved.

    Alternatively, as shown in FIG. 39, the light emitting elements 32 may be arranged in a staggered manner so that the light emitting elements 32 are shifted in the longitudinal direction by one pitch of the LED chip arrangement in every other row. According to this method, since LED chips of any color are not arranged in a line, the effect of eliminating striped color unevenness is high.

(Embodiment 15)
Next, a method of arranging the LED chips 36r, 36g, and 36b for each emission color will be described. The brightness of the red LED chip 36r, the green LED chip 36g, and the blue LED chip 36b is not actually equal, so that when the same number is used, color balance cannot be achieved. Therefore, in order to adjust the degree of whiteness (white balance) of the surface illumination device 31, it is desirable to determine the ratio of the LED chips according to the amount of light of each LED chip 36r, 36g, 36b. For example, in the light-emitting element 32 (Embodiment 15) shown in FIG. 40, a red LED chip having a relatively large maximum rating and capable of emitting light twice as much as the blue LED chip 36b and the green LED chip 36g. Since 36r is used, the three red LED chips 36r, the six green LED chips 36g, and the six LED chips 36b constitute the light emitting element 32 and the light guide plate 40. If such a light emitting element 32 is used, the number of LED chips used in the light emitting element 32 can be reduced, and the reliability (life) is improved.

(Embodiment 16)
FIG. 41 is a diagram showing a light emitting device 32 and its arrangement according to Embodiment 16 of the present invention. In order to eliminate the row of the same emission color in the surface illumination device 31 and to improve the color mixing property, an LED chip is not placed in the center of the light emitting element 32, and an even number of LED chips 36r and 36g of each color are provided in the light emitting element 32. 36b are preferably arranged asymmetrically at equal intervals. In the example of FIG. 41, four red LED chips 36r, six green LED chips 36g, and six blue LED chips 36b are arranged in this way.

  When such light emitting elements 32 are arranged in the X direction and the Y direction, as shown in FIG. 41, the light emitting elements 32 are arranged in the same direction in the X direction in each column, and in the Y direction. The light emitting elements 32 are rotated by 180 ° for each row. By arranging in this way, the red LED chips 36r, the green LED chips 36g, and the blue LED chips 36b are distributed at substantially equal intervals in the X direction and the Y direction. Can be improved

(Embodiment 17)
FIG. 42 is a plan view showing the arrangement of LED chips in the light emitting device according to Embodiment 17 of the present invention. In the light emitting element 32 of Embodiment 17, a plurality of rows of LED chips are arranged in the Y direction in the light emitting element 32 in order to improve color mixing in the Y direction. At this time, if the LED chips 36r, 36g, and 36b are arranged at intervals in the Y direction, the colors are separated due to refraction at the back surface of the light guide plate 40, and the color mixing property may be deteriorated. It is desirable that the chips 36r, 36g, and 36b be arranged as close to the central axis parallel to the X direction of the light guide plate 40 as possible.

  In terms of improving color mixing, it is desirable that the LED chips 36r, 36g, and 36b in each row be close to each other to be closely packed. However, if the LED chips 36r, 36g, and 36b are too close to each other, the adjacent LED chips 36r, 36g are arranged. , 36b increases, and the light utilization efficiency decreases. In order to reduce absorption by the adjacent LED chips 36r, 36g, and 36b, it is preferable to arrange the LED chips 36r, 36g, and 36b in a staggered manner in a plurality of rows as shown in FIG.

  Further, in order to suppress the absorption of light by the adjacent LED chips 36r, 36g, 36b, as shown in FIG. 44, each LED chip 36r, 36g, 36b is accommodated in a concave reflecting cup 48 and a substrate 39 is placed. The LED chip 36r, 36g, 36b adjacent to each other may be shielded by the reflection cup 48. For this reason, it is desirable that the LED chips 36r, 36g, and 36b be arranged at an interval that allows at least the reflective cup 48 to be produced in both the X direction and the Y direction.

(Embodiment 18)
45 (a) and 45 (b) are diagrams for explaining the eighteenth embodiment of the present invention. When the light emitting element 32 is disposed in the surface illumination device 31, there may be a case where a space having a relatively wide width K may be provided between the light emitting elements 32 in the X direction due to wiring or the like. In such a case, as shown in FIG. 45 (a), the gap between the LED chips increases between the light emitting elements 32 adjacent in the X direction, and the amount of light may decrease in this portion, resulting in darkness.

  FIG. 45B shows an embodiment 18 of the present invention in which the amount of light is not reduced in the space portion even when a relatively wide space is generated between the light emitting elements 32. In the eighteenth embodiment, the distance between adjacent LED chips is increased at the central portion in the light emitting element 32, and the distance between adjacent LED chips is decreased at the end portion. As a result, the light emission density is suppressed at the central portion of the light emitting element 32 and the light emission density is increased at the end portion, so that it is possible to prevent the light amount from being insufficient between the light emitting elements 32.

  In addition, as a method for preventing the light amount from being insufficient in the space portion between the adjacent light emitting elements 32, an LED chip located at an end portion in the light emitting element 32 can be made to flow a larger current using a chip having a larger area. The light emission amount may be increased at the end of the light emitting element 32.

  Moreover, when the area and size of the surface illumination device 31 are increased, the LED chips may be arranged in a similar arrangement by expanding the LED chip arrangement as described above. However, depending on the application, a high-luminance surface illumination device 31 or a thin surface illumination device 31 may be required.

  When it is desired to design the surface illumination device 31 for high brightness use, the number of LED chips in the light emitting element 32 may be increased or the input power to each LED chip may be increased. In order to increase the luminance by using the light emitting elements, it is only necessary to reduce the arrangement pitch of the light emitting elements 32 in the Y direction and increase the number of light emitting elements 32 to be mounted. In that case, since the overlapping degree of the light emitted from the light emitting element 32 in the width direction becomes large, the irradiation range by the light emitting element 32 with the apex angle of the convex portion 42 formed on the back surface of the light guide plate 40 being an obtuse angle. By narrowing, the degree of light overlap can be reduced and the uniformity of luminance can be maintained.

  Further, when the surface illumination device 31 is thinned, if the thickness of the light emitting elements 32 is reduced, the overlapping degree of the light emitted from each light emitting element 32 is reduced, and thus the area between the light emitting elements 32 becomes dark. In order to suppress such a problem, the arrangement pitch of the light emitting elements 32 in the Y direction may be narrowed, but the apex angle of the convex portion 42 on the back surface of the light guide plate 40 is an acute angle even with the same arrangement pitch. If the irradiation range is widened, the uniformity of luminance in the surface illumination device 31 can be maintained.

(Embodiment 19)
FIG. 46 is a schematic diagram for explaining a surface illumination device 31 according to a nineteenth embodiment of the present invention. In the surface illumination device 31 of the nineteenth embodiment, the light emitting elements 32 arranged side by side in the X direction and the Y direction are partitioned by a partition wall 49. If the light emitting elements 32 are partitioned by the partition wall 49 in this way, the surface illumination device 31 can be driven, turned on, and turned off for each area according to the image of the liquid crystal display panel, thereby reducing power consumption. And moving image characteristics (moving image blur) can be improved.

  Since the gap between the light emitting elements 32 is relatively narrow in the X direction, a plate-shaped member as shown in FIG. 47A may be used as the partition wall 49 arranged parallel to the Y direction. In addition, since the gap between the light emitting elements 32 is relatively wide in the Y direction, the partition wall 49 arranged in parallel with the X direction is the one having an inclined surface as shown in FIG. It is desirable to reflect the light forward.

(Embodiment 20)

  FIG. 48A is a cross-sectional view showing a cross section along the X direction of the light emitting device 32 according to Embodiment 20 of the present invention, and FIG. 48B is a cross sectional view showing a cross section along the Y direction. In the light emitting device 32 of the twentieth embodiment, a plurality of cup-shaped recesses 51 are formed on the inner surface of a package 50 formed of a high-reflectance molding resin (for example, white resin). The LED chips 36r, 36g, and 36b are accommodated and mounted, and the recesses 51 are filled with a sealing resin 37 such as an epoxy resin or a silicone resin to seal the LED chips 36r, 36g, and 36b. Steps 52 are formed on both side surfaces in the package 50, and claw insertion holes 53 are formed on both end surfaces in the package 50. The light guide plate 40 is separated from the sealing resin 37 by inserting claws 54 provided at both ends thereof into the claw insertion holes 53 of the package 50 and placing both side portions of the lower surface on the step portions 52 of the package 50. It is fixed to the upper surface of the.

  There is a method in which the light guide plate 40 and the package 50 are bonded and fixed by filling the package 50 with a sealing resin 37 or the like. In such a method, the light guide plate 40 is used to cure the sealing resin 37 or the like. However, the light guide plate 40 is required to have heat resistance more than necessary, the cost of the light guide plate 40 is increased, and optical characteristics (such as transmittance) are required. There is a risk of getting worse. On the other hand, in the light emitting element 32 of the twentieth embodiment, the sealing resin 37 is not filled between the package 50 and the light guide plate 40, and a space is formed between the sealing resin 37 and the lower surface of the light guide plate 40. Thus, the light guide plate 40 can be attached to the package 50 after the sealing resin 37 is cured, and the problem that the light guide plate 40 needs more heat resistance than necessary can be solved. it can.

  In the light emitting element 32 of the twentieth embodiment, since the LED chips 36r, 36g, and 36b are arranged in the cup-shaped recess 51, the light emitted from the LED chips 36r, 36g, and 36b is adjacent to the LED chip 36r. , 36g, and 36b can be prevented from being absorbed and light loss can be reduced.

(Embodiment 21)
FIG. 49A is a cross-sectional view showing a cross section along the X direction of the light emitting element 32 (the light guide plate 40 is omitted) according to Embodiment 21 of the present invention, and FIG. 49B is the Y direction thereof. It is sectional drawing which shows the cross section along. In the light emitting element 32 of Embodiment 21, the surface of the sealing resin 37 that seals the LED chips 36r, 36g, and 36b in the package 50 is formed in a convex lens shape. In this embodiment, since the surface of the sealing resin 37 has a lens shape, it is possible to improve the extraction efficiency of light emitted from the light emitting element 32, particularly in the Y direction, and in the width direction (Y direction). The light can be spread over a wide range.

  The lens-shaped sealing resin 37 may be separately formed into a spherical lens shape. However, it is better to pot an uncured resin into the recess 51 of the package 50 to form a lens shape with surface tension, and then to cure. , Preferable for cost reduction. At this time, in order to make the sealing resin 37 into a spherical lens shape by surface tension, it is preferable to provide resin-stopping walls 55 on both sides of the recess 51 as shown in FIG.

  In addition, in order to improve the color mixing property in the X direction, resin is not potted for each recess 51, but as shown in FIG. The sealing resin 37 is preferably connected in the X direction. By doing so, variation in potting shape and the like can be reduced, and further, light diffuses in the sealing resin 37 and color mixing properties are improved. Furthermore, in order to increase the degree of diffusion, a diffusing material may be dispersed in the sealing resin 37.

(Embodiment 22)
FIG. 51 is a schematic view showing a wiring method of the LED chips 36r, 36g, 36b in the light emitting element 32. FIG. Each of the LED chips 36r, 36g, and 36b is electrically connected inside the package 50, whereby the red LED chip 36r is connected to the pair of lead terminals 56r, and the green LED chip 36g is connected to the pair of lead terminals 56g. The blue LED chip 36b is connected to the pair of lead terminals 56b.

  However, in the structure as shown in FIG. 51, the inside of the light emitting element 32 becomes a complicated structure. Therefore, in the light emitting element 32 of Embodiment 22, as shown in FIGS. 52 (a) and 52 (b), a pair of lead terminals 56 is provided for each of the LED chips 36r, 36g, and 36b. Thus, if a pair of lead terminals 56 is provided for each LED chip, the current applied to each LED chip can be individually adjusted even if the LED chips vary.

(Embodiment 23)
FIG. 53 is a cross-sectional view showing the structure of the light emitting device 32 according to Embodiment 23 of the present invention. FIG. 54 is an exploded view of the light emitting device 32 according to Embodiment 23 and a plan view showing a part of the light guide plate 40. In this embodiment, as shown in FIG. 54, a plurality of heat caulking projections 57 project from the upper surface of the outer peripheral portion of the package 50, and heat caulking holes 58 are formed at positions facing the light guide plate 40. Is provided. Thus, when the light emitting element 32 is assembled, after the light sources 38r, 38g, and 38b are completely mounted in the package 50, the heat caulking projections 57 are inserted into the heat caulking holes 58 to be placed on the package 50. The light guide plate 40 is placed, and then heat is applied to the heat caulking projections 57 to crush them. Therefore, as shown in FIG. 53, the light guide plate 40 is fixed on the package 50 by the heat caulking projection 57. According to this method, there is no possibility that the light guide plate 40 is unexpectedly detached from the package 50.

  Further, as shown in FIG. 55, it is desirable that a portion of the lower surface of the light guide plate 40 placed on the stepped portion 52 of the package 50 be a flat surface without providing the convex portion 42. If the portion on the stepped portion 52 is a flat surface, the fixing accuracy of the light guide plate 40 is improved and the position of the light guide plate 40 is stabilized. Furthermore, if a flat surface is provided on the back surface of the light guide plate 40 as described above, the light guide plate 40 formed at the time of forming the light guide plate 40 can be used as a protruding portion for protruding by an eject pin. . At this time, it is desirable not to provide the recess 41 in the peripheral portion of the surface of the light guide plate 40.

(Other)
Although not shown, the following methods are also conceivable as an arrangement method of the LED chips 36r, 36g, and 36b. When the surface illumination device 31 is required to have higher luminance and lower power consumption, a pseudo white LED having a high luminous efficiency combining a blue LED chip and a phosphor (yellow) may be used as a light source. For example, a pseudo white LED may be appropriately arranged in a large number of red light sources 38r, green light sources 38g, and blue light sources 38b. Furthermore, when color reproducibility is not particularly required, pseudo white LEDs may be used in place of the light sources 38r, 38g, and 38b.

  In addition, when it is required that there is no color variation of red, green, and blue, a light source that combines an ultraviolet LED chip and red, green, and blue phosphors may be used. For example, a light source composed of an ultraviolet LED chip and red, green, and blue phosphors may be appropriately disposed in a large number of red light sources 38r, green light sources 38g, and blue light sources 38b.

  When color reproducibility is required over a wide range of colors, LED chips having wavelengths different from the emission wavelength range of the red LED chip 36r, the green LED chip 36g, and the blue LED chip 36b are mixedly used. May be. Normally, a red LED chip 36r having a center wavelength of about 620 nm, a green LED chip 36g having a center wavelength of about 530 nm, and a blue LED chip 36b having a center wavelength of about 465 nm are used. You may mix the LED chip with a wavelength whose near center wavelength is longer than 620 nm, or mix the LED chip whose wavelength nearer ultraviolet is shorter than 465 nm. Further, an LED chip having an intermediate wavelength between the red light of the LED chip 36r and the green light of the LED chip 36g is mixed, or an LED chip having an intermediate wavelength between the blue light of the LED chip 36b and the green light of the LED chip 36g. Even if they are mixed, the range of good color reproducibility is widened.

  With regard to the number of LED chips mounted, basically, as the number of LED chips mounted increases, the package size of the light emitting element 32 and the like increase, and the unit price of the light emitting element 32 increases. In addition, when a large number of LED chips are mounted in one package, luminance deterioration and color change due to heat generated from the LED chips when turned on increases. Furthermore, when the number of mounted LED chips increases, the package of the light emitting element 32 and the light guide plate 40 become larger (particularly, the length in the X direction becomes longer), which causes production problems such as warpage of the light emitting element 32. Arise. However, in applications that require a large number of LED chips or light sources such as a backlight, assembly costs, wiring, and board costs for making a backlight unit are also important, so it is more costly to have as few packages as possible. Is desirable. Therefore, it is desirable that the number of LED chips mounted on the light emitting element 32 be an appropriate number depending on the application of the surface illumination device 31 and the like.

  For example, when the surface illumination device 31 is used as a backlight, the demand for luminance deterioration and color change is severe, so it is desirable to suppress the temperature change to about 10 ° C. or less. Therefore, in this case, if a package with good heat dissipation (for example, a package using a substrate acting as a heat sink) is used, the input power to the light emitting element 32 is preferably 1.5 W or less. For example, 15 LED chips may be mounted on one light emitting element 32 and power of about 0.1 W may be supplied to one LED chip.

  In addition, the length of the light emitting element 32 in the X direction is preferably about 60 mm so that warp or the like does not occur and the largest possible range can be irradiated. Note that various combinations of the number of LED chips mounted and the size of the light emitting element 32 are conceivable depending on the luminance (brightness) and area required for the backlight.

FIG. 1 is a plan view of a backlight disclosed in Patent Document 1. 2A is a cross-sectional view taken along line A1-A1 in FIG. 1, and FIG. 2B is a cross-sectional view taken along line A2-A2 in FIG. FIG. 3 is a plan view of the backlight disclosed in Patent Document 2. FIG. FIG. 4 is an enlarged cross-sectional view of the B1-B1 line cross section and the B2 portion of FIG. FIG. 5 is a plan view showing the surface illumination device according to Embodiment 1 of the present invention. 6 is a cross-sectional view taken along line C1-C1 of FIG. 7 is a cross-sectional view taken along line C2-C2 of FIG. FIG. 8A is a perspective view from the front surface side showing an enlarged part of the light guide plate, and FIG. 8B is a perspective view from the rear surface side showing an enlarged part of the light guide plate. FIG. 9A is an enlarged view showing a cross section perpendicular to the short direction (Y direction) of the light guide plate, and FIG. 9B is an enlarged view showing a cross section perpendicular to the longitudinal direction (X direction). FIG. 10 is a diagram illustrating the behavior of light in a cross section parallel to the ZX plane of the light guide plate. FIG. 11 is a diagram illustrating the behavior of light in a cross section parallel to the ZY plane of the light guide plate. 12 shows a luminance distribution of a conventional example in which three white light emitting elements (9 LED chips) used in the backlight shown in FIG. 3 are arranged, and the present invention in which nine LED chips are arranged in a line. It is a figure showing the result of having measured the luminance distribution of the light emitting element of an Example. FIG. 13 is a cross-sectional view of a light emitting device in which light does not leak from the side surface. FIG. 14: is a schematic sectional drawing which shows the structure of the surface lighting apparatus concerning Embodiment 2 of this invention. FIG. 15 is a diagram illustrating the apex angle α of the convex portion having a triangular cross section provided on the back surface of the light guide plate. FIG. 16 is a diagram for explaining a design policy of the convex portion on the back surface of the light guide plate. FIG. 17 is a schematic view showing a part of a cross section of a light guide plate according to Embodiment 3 of the present invention. FIG. 18 is a diagram illustrating the relationship between the distance between the LED chip and the convex portion and the behavior of light. FIG. 19 is a schematic view showing a part of a cross section of a light emitting device according to Embodiment 4 of the present invention. FIG. 20 is a schematic view showing a part of a cross section of a light guide plate used in a light emitting device according to Embodiment 5 of the present invention. FIG. 21 is a diagram illustrating the apex angle β of the conical recess provided on the surface of the light guide plate. FIG. 22 is a diagram for explaining the relationship between the arrangement pitch of the light sources and the apex angle β of the light guide plate surface. FIG. 23 is a schematic diagram showing the structure of a surface illumination device according to Embodiment 6 of the present invention. FIG. 24A is a plan view showing a light emitting element according to Embodiment 7 of the present invention, and FIG. 24B is an enlarged perspective view from the back side of the light guide plate used in the light emitting element. FIG. 25 is an enlarged perspective view from the surface side of the light guide plate according to Embodiment 8 of the present invention. FIG. 26 is a plan view showing a light emitting device according to Embodiment 9 of the present invention. FIG. 27A is an enlarged perspective view from the front surface side of the light guide plate of the ninth embodiment, and FIG. 27B is an enlarged perspective view from the rear surface side of the light guide plate of the ninth embodiment. FIGS. 28A, 28B, and 28C are schematic views showing various convex shapes according to the tenth embodiment of the present invention. 29 (a), 29 (b), and 29 (c) are schematic views showing various recessed portions according to the tenth embodiment of the present invention. FIG. 30 is a cross-sectional view showing the structure of the light emitting device according to Embodiment 11 of the present invention. FIG. 31 is a cross-sectional view showing a modification of the eleventh embodiment. FIG. 32 is a cross-sectional view showing another modification of the eleventh embodiment. FIG. 33 (a) is a schematic plan view showing the position of the convex portion in the light emitting device according to Embodiment 12 of the present invention, and FIG. 33 (b) is a sectional view taken along the line DD of FIG. 33 (a). FIG. 34A is a plan view showing a light emitting element according to Embodiment 13 of the present invention, and FIG. 34B is a sectional view showing a section in the light source arrangement direction of Embodiment 13. FIG. 35 is a plan view showing an LED chip arrangement in a conventional light emitting device. FIG. 36 is a plan view showing an LED chip arrangement in a light emitting device according to Embodiment 14 of the present invention. FIG. 37 is a plan view showing a state in which the light emitting elements according to the fourteenth embodiment are also arranged in the Y direction. FIG. 38 is a plan view showing a state in which the light emitting elements according to the fourteenth embodiment are arranged in the Y direction in an improved arrangement. FIG. 39 is a plan view showing another state in which the light emitting elements according to the fourteenth embodiment are arranged in the Y direction. FIG. 40 is a plan view showing an LED chip arrangement in the light emitting device according to Embodiment 15 of the present invention. FIG. 41 is a diagram illustrating a light emitting element and an arrangement thereof according to the sixteenth embodiment of the present invention. FIG. 42 is a plan view showing the arrangement of LED chips in the light emitting device according to Embodiment 17 of the present invention. FIG. 43 is a plan view showing another example in which LED chips are arranged in a plurality of rows in the light emitting element. FIG. 44 is a cross-sectional view showing the LED chip disposed in the reflection cup. 45 (a) and 45 (b) are diagrams for explaining the eighteenth embodiment of the present invention. FIG. 46 is a schematic diagram for explaining a surface illumination device according to Embodiment 19 of the present invention. 47 (a) and 47 (b) are perspective views showing the shape of a partition wall used in the surface illumination device of the nineteenth embodiment. 48A is a cross-sectional view showing a cross section along the X direction of the light emitting device according to Embodiment 20 of the present invention, and FIG. 48B is a cross sectional view showing a cross section along the Y direction. FIG. 49A is a cross-sectional view showing a cross section along the X direction of the light emitting element (the light guide plate is omitted) according to Embodiment 21 of the present invention, and FIG. 49B is along the Y direction. FIG. FIG. 50 is a cross-sectional view showing a modification of the twenty-first embodiment. FIG. 51 is a schematic diagram illustrating an example of wiring in a light-emitting element. FIG. 52 is a schematic view showing an example of wiring of a light emitting device according to Embodiment 22 of the present invention. FIG. 53 is a cross-sectional view showing the structure of the light emitting device according to Embodiment 23 of the present invention. FIG. 54 is an exploded view of the light emitting device according to the twenty-third embodiment. FIG. 55 is a cross-sectional view showing the structure of the portion where the light guide plate is placed on the step portion of the package.

Explanation of symbols

31 surface illumination device 32 light emitting element 33 diffusing member 35 reflecting member 36b LED chip 36g LED chip 36r LED chip 38b blue light source 38g green light source 38r red light source 40 light guide plate 41 concave portion 42 convex portion 44 prism sheet 45 polarizing sheet 46 diffusion region 47 Transparent member 48 Reflecting cup 49 Partition wall 50 Package 52 Step part 53 Claw insertion hole 54 Claw 55 Wall 56, 56r, 56g, 56b Lead terminal 57 Protrusion for heat caulking 58 Heat caulking hole Lb Blue light Lg Green light Lr Red light

Claims (22)

A light emitting device having a long shape in one direction, in which a plurality of light sources are arranged along the longitudinal direction, and a light guide plate is disposed so as to cover all the light sources so as to face the light emitting direction of each light source. There,
The light guide plate refracts the light incident from the light source on the surface facing the light source so that the directivity characteristics spread on the short side of the light emitting element, and reflects the light reflected on the opposite surface. A first optical surface for total reflection, and a part of the light incident from the light source is reflected on a surface opposite to the surface facing the light source, and the remaining light is transmitted to thereby emit the light. A light-emitting element having a second optical surface that emits light having wide directivity toward the short side of the element.   The first optical surface of the light guide plate is characterized in that triangular prism-shaped convex patterns whose slopes are located in the short direction of the light guide plate are arranged along the short direction of the light guide plate. The light emitting device according to claim 1.   The first optical surface of the light guide plate is formed by arranging cone-shaped convex patterns having slopes in the short and long directions of the light guide plate along the short and long directions of the light guide plate. The light emitting device according to claim 1, wherein:   The first optical surface of the light guide plate is formed by arranging, on the light guide plate, cone-shaped convex patterns whose slopes are located obliquely with respect to the short and long directions of the light guide plate. The light emitting device according to claim 1, wherein the light emitting device is characterized.   The cross-sectional shape of the convex pattern in the short direction of the light guide plate is asymmetric, and the one-side vertical angle on the side farthest from the light source closest to the convex pattern in the cross-section is the one-side vertical angle on the side closest to the light source closest to the convex pattern The light-emitting element according to claim 2, wherein the light-emitting element is larger than the light-emitting element.   6. The light emitting device according to claim 5, wherein the one-side apex angle on the side farthest from the light source closest to the convex pattern in the cross section gradually increases as the convex pattern becomes farther from the light source.   5. The light emitting device according to claim 2, wherein the height of the convex pattern gradually decreases as the distance from the light source closest to the convex pattern increases. 6.   The apex angle of the convex pattern in the cross section of the convex pattern parallel to the short direction of the light guide plate is different from the apex angle of the convex pattern in the cross section of the convex pattern parallel to the longitudinal direction of the light guide plate. The light-emitting element according to claim 3 or 4, characterized in that   The second optical surface of the light guide plate is configured by a conical concave pattern that is recessed on a surface opposite to a surface facing the light source of the light guide plate. Item 2. A light emitting device according to Item 1.   The apex angle of the concave pattern in the cross section of the concave pattern parallel to the short direction of the light guide plate is different from the apex angle of the concave pattern in the cross section of the concave pattern parallel to the longitudinal direction of the light guide plate. The light emitting device according to claim 9, wherein the light emitting device is characterized.   2. The light emitting device according to claim 1, wherein the second optical surface of the light guide plate is provided with a diffusion region on a surface opposite to a surface facing the light source of the light guide plate.   The light emitting device according to claim 1, wherein the light sources are arranged in a line along a longitudinal direction of the light emitting device.   The light emitting device according to claim 1, wherein the plurality of light sources are a plurality of types of light sources having different emission colors.   The light emitting device according to claim 13, wherein the light sources are a red light source, a green light source, and a blue light source.   The light emitting device according to claim 13, wherein the light emission colors of the light sources arranged at both ends are different.   The light emitting device according to claim 13, wherein the light source includes a white light source.   Each light source is housed in a package, an LED chip is mounted in a recess provided in the package, and the LED chip is sealed in the sealing resin by potting a sealing resin in the recess. The light emitting device according to claim 1.   Each light source is housed in a package, and a step portion for supporting an edge of the light guide plate is provided on a side surface of the package, and the convex pattern is formed in a region supported by the step portion of the light guide plate. The light emitting device according to claim 1, wherein the light emitting device is not.   14. A surface illumination device in which the light-emitting elements according to claim 1 or 13 are arranged at a relatively small interval in the longitudinal direction and at a relatively large interval in the short direction.   The light source is a plurality of types of light sources having different emission colors, and the light emitting elements are arranged so that the light sources of the respective emission colors are equally spaced in the longitudinal direction. The light emitting element as described in.   The surface illumination device according to claim 19, wherein a reflective member is disposed in the gap between the light emitting elements or behind the gap.   The surface illumination device according to claim 19, wherein a diffusion sheet is disposed in front of the light emitting element.

Images