JP2013251082A - Light source module, and liquid crystal display and lighting device equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain both optimization of luminance distribution of light and enhancement of light extraction efficiency.SOLUTION: In a light source module, a light guide plate 20 consists of a main light guide part 21 with an emission face 20b and having rugged shape bodies T formed on a rear face 21c, and a sub light guide part 22 filling gaps among the rugged shape bodies T. When optical refraction indexes of the main light guide part 21, the sub light guide part 22, and the atmosphere are respectively denoted by n1, n2, and n0, following formula (1) is satisfied. n1>n2>n0 (1).

Description

  The present invention relates to a light source module, a liquid crystal display device including the light source module, and an illumination device.

  In recent years, in order to reduce the thickness of a liquid crystal display device, a backlight including a side edge type light guide plate that emits light from a light source in a planar shape by the light guide plate is frequently used.

  For example, Patent Document 1 discloses a light source including a light guide plate having an emission surface made of a transparent material and having a plurality of prisms each having a substantially triangular cross section, and a transparent resin in close contact with the prism. An apparatus is disclosed. The transparent resin in close contact with the prism is made of a transparent material having a refractive index different from that of the light guide plate. The technique of Patent Document 1 is intended to realize a light source device that has high in-plane uniformity of emitted light and has a narrow emission angle distribution of light regardless of the distance from the light source.

  Patent Document 2 discloses an illumination device including a light guide plate, a light source disposed on a side surface of the light guide plate, and a prism row formed on the back surface of the light guide plate. The technology of Patent Document 2 aims to realize an illumination device that reduces the number of optical sheets and LEDs, and improves the uniformity and utilization efficiency of light.

Japanese Patent Laying-Open No. 2006-261088 (published September 28, 2006) JP 2011-113903 A (released on June 9, 2011)

  However, the conventional technology as described above has a problem that it is difficult to achieve both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency on the exit surface.

  When the light guide plate is large (for example, 60 type), the light extraction efficiency at the exit surface is improved and the intensity of the emitted light is made uniform within the exit surface of the light guide plate or the intensity is maximized at the center. Is required. As in Patent Document 2, in the technique of extracting the propagating light propagating through the light guide plate by the prism row formed on the back surface of the light guide plate at the emission surface, the light extraction efficiency is increased by the light rising effect by the prism row. Can be improved. However, since the light extraction effect by the prism row is too high, the luminance distribution in the exit surface of the light guide plate is a distribution in which the intensity of the emitted light near the light incident end surface is extremely high. Therefore, it is difficult to optimally adjust the luminance distribution. In the technique of Patent Document 2, in order to optimize the luminance distribution while maintaining the light rising effect by the prism array, it is necessary to form an extremely fine prism array. Such a fine prism array is difficult to manufacture.

  Therefore, with the technique of Patent Document 2, it is difficult to achieve both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency on the exit surface.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to optimize the luminance distribution of light extracted from the exit surface of the light guide plate and to improve the light extraction efficiency on the exit surface. It is an object of the present invention to provide a light source module capable of achieving both of the above, a liquid crystal display device and an illumination device including the same.

In order to solve the above-described problems, the light source module of the present invention includes a light guide plate that emits light incident in a direction perpendicular to the end surface from at least one of a pair of opposed end surfaces, and light that is incident on the light guide plate. A light source module including a plurality of light sources incident on the light guide plate, wherein the light guide plate includes the main light portion having the light exit surface and a concave / convex shape formed on a back surface opposite to the light exit surface, and the concave / convex shape. When the light refractive indices of the main light portion, the sub light guide portion, and the atmosphere are n1, n2, and n0, the following formula (1) is formed.
n1>n2> n0 (1)
It is characterized by satisfying.

  According to said structure, it is the structure which the said sub light guide part fills the clearance gap between the uneven | corrugated shapes formed in the said leading light part. That is, according to the above configuration, the light guide plate has a two-layer structure including the leading light portion and the sub light guiding portion, and the leading light portion and the sub light guiding portion have an uneven interface. Are in close contact with each other. Further, according to the above configuration, the sub light guide portion is made of a material whose light refractive index n2 is lower than the light refractive index n1 of the main light portion and higher than the light refractive index n0 of the atmosphere. Yes. By adopting such a configuration, it is possible to suppress the improvement of the light extraction efficiency due to the concavo-convex shape and reduce the light extraction efficiency while maintaining the light rising effect due to the concavo-convex shape. As a result, according to the above configuration, since the density of the uneven shape can be lowered even if the size of the uneven shape is large, the luminance distribution can be optimized. At the same time, light can be raised perpendicular to the exit surface. Therefore, according to the above configuration, it is possible to achieve both optimization of the luminance distribution in the emission surface and improvement in the luminance of light in the vertical direction (relative to the emission surface).

  From the above, according to the above configuration, a light source module capable of achieving both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency at the exit surface is realized. can do.

In the light source module of the present invention, the following formulas (2) and (3)
n1-n2> 0.05 (2)
n2-n0> 0.30 (3)
It is preferable to satisfy.

  The inventors of the present invention set optimal optical refractive indexes n1, n2, and n0 to achieve both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency on the exit surface. We have intensively studied. As a result, by setting the light refractive index n1 of the leading light portion and the light refractive index n2 of the sub light guide portion as in the above configuration, the light that is more reliably extracted from the exit surface of the light guide plate It has been found that both the optimization of the luminance distribution of the light source and the improvement of the light extraction efficiency on the exit surface can be achieved.

  In the light source module of the present invention, when the direction perpendicular to the end face of the light guide plate is the first direction, the uneven shape on the back surface is a streak extending in a direction perpendicular to the first direction. It is preferable that

  In the above configuration, by reducing the density (groove density) of the concavo-convex shape in the vicinity of the end surface where light is incident, and increasing the density of the concavo-convex shape at a position far from the end surface where the light is incident in the first direction. The luminance distribution of the entire light guide plate can be improved. For this reason, according to said structure, there exists an advantage that luminance distribution can be improved with the simple structure of changing the density of uneven | corrugated shape.

  In the light source module of the present invention, when the concavo-convex height of the concavo-convex shape is H and the thickness of the light guide plate is D, the concavo-convex height H is 0.3% or more of the thickness D of the light guide plate. It is preferable that

  When the uneven height H of each uneven shape is less than 0.3% of the thickness D of the light guide plate 20 and the size per uneven shape is too small, the light guide plate expands due to heat generated from the light source, The uneven shape is crushed. For this reason, the light extraction amount due to the uneven shape changes. Assuming this point, according to the above configuration, the uneven height H is set to 0.3% or more of the thickness D of the light guide plate. Unlike the prior art, in the light source module of the present invention, the luminance distribution on the exit surface can be optimally controlled even when the size of the concavo-convex shape is large as in the above configuration.

  In the light source module of the present invention, when the direction perpendicular to the end face of the light guide plate is the first direction, the length of the light guide plate in the first direction is preferably 300 mm or more.

  In the light source module of the present invention, even if a large light guide plate having a long length (light guide distance) in the first direction is used as in the above configuration, the density of the uneven shape is reduced in the vicinity of the end face where light enters. In addition, it is possible to increase the density of the concavo-convex shape at a position far from the end face where the light is incident in the first direction. As a result, even with the above configuration, the luminance distribution can be optimized.

  In order to solve the above-described problems, a liquid crystal display device according to the present invention includes the above-described light source module.

  According to the above configuration, since the above-described light source module is provided, it is possible to achieve both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency on the exit surface. A liquid crystal display device can be realized.

  In order to solve the above-described problems, an illumination device according to the present invention includes the above-described light source module.

  According to the above configuration, since the above-described light source module is provided, it is possible to achieve both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency on the exit surface. A simple lighting device can be realized.

In the light source module of the present invention, as described above, the light guide plate has a light-emitting portion having the exit surface and an uneven shape formed on the back surface opposite to the exit surface, and a gap between the uneven shapes. When the light refractive indexes of the leading light portion, the sub light guiding portion, and the atmosphere are n1, n2, and n0, the following formula (1)
n1>n2> n0 (1)
It is the composition which satisfies.

  Moreover, the liquid crystal display device of this invention is the structure provided with the said light source module as mentioned above.

  Moreover, the illuminating device of this invention is the structure provided with the said light source module as mentioned above.

  Therefore, it is possible to achieve both optimization of the luminance distribution of light extracted from the exit surface of the light guide plate and improvement of light extraction efficiency on the exit surface.

It is a disassembled perspective view which shows the structure of the liquid crystal display device provided with the light source module of this invention. It is principal part sectional drawing which shows the structure of the said liquid crystal display device. It is sectional drawing which showed typically the structure of the light-guide plate of a light source module. FIG. 4 is a schematic diagram for explaining the operation and effect of the light source module of FIG. 3, and (a) shows an optical path of propagating light in the vicinity of the concavo-convex shape body of the main light portion when a sub light guide portion is provided; (B) shows the optical path of the propagation light in the vicinity of the concavo-convex shape body of the main light portion when the sub light guide portion is not provided. It is a graph which shows the light intensity distribution of the light guide direction (Y direction) of the output surface in a light source module about the case where a sub light guide part is provided, and the case where a sub light guide part is not provided. When the length in the light guide direction is 200 mm, the pitch of the concavo-convex shape body T is 1.0 mm, and the material of the main light portion is acrylic resin, the light extraction efficiency difference n1-n2 and n2-n0 and the light extraction efficiency ( It is a graph which shows the correlation with the main light guide part side and the sub light guide part side. (A)-(d) is sectional drawing which shows the various shapes of the uneven | corrugated shaped body formed in the back surface of the main light part in the light-guide plate of the said light source module. It is sectional drawing which shows the whole structure of the information display apparatus provided with the light source module of FIG.

(Configuration of liquid crystal display device)
First, an overall configuration of a liquid crystal display device including the light source module according to the present embodiment will be described with reference to FIGS. FIG. 1 is an exploded perspective view showing a configuration of a liquid crystal display device provided with the light source module of the present embodiment. FIG. 2 is a cross-sectional view of the main part showing the configuration of the liquid crystal display device.

  For example, a liquid crystal display device 1 as an electronic apparatus including the light source module 10 of the present embodiment is configured by a chassis 2, a light source module 10, a liquid crystal panel 3, and a bezel 4 in order from the back, as shown in FIG. The light source module 10 includes a reflection sheet 11 as a reflection plate, a light guide plate 20, a lower diffusion sheet 17, and an upper diffusion sheet 18.

  On the side of at least one end face 20a of the pair of end faces 20a and 20a of the light guide plate 20 of the light source module 10, as shown in FIG. 2, a light source provided with an LED 12, a LED substrate 13, and a reflector 14 as a light source. A unit 15 is provided. In addition, an uneven shape body (not shown) is formed in the vicinity of the lower surface 20c as a surface opposite to the light exit surface 20b of the light guide plate 20. The light guided inside the light guide plate 20 is taken out by the uneven shape body. Thereby, the light from the LED 12 is incident on one end surface 20a of the light guide plate 20, and the light is guided while totally reflecting the inside of the light guide plate 20, and a plurality of light beams provided near the lower surface 20c of the light guide plate 20 are provided. The total reflection condition is broken by the uneven shape body, and the liquid crystal panel 3 is irradiated with light from the emission surface 20 b of the light guide plate 20 through the lower diffusion sheet 17 and the upper diffusion sheet 18. The operation of the uneven shape body will be described later.

  Therefore, the light source module 10 of the present embodiment employs a side edge (also referred to as side light) method. Although light is emitted from the light guide plate 20 from other surfaces than the light exit surface 20b, the reflection sheet 11 is disposed on a surface other than the light exit surface 20b of the light guide plate 20 and the surface on which the LEDs 12 are disposed. Since the light enters the optical plate 20, most of the light is emitted from the emission surface 20b. Here, the light source unit 15 is provided on only one of the pair of end surfaces 20a along the longitudinal direction of the light guide plate 20, for example. However, the present invention is not necessarily limited thereto, and the light source unit 15 may be provided on both the pair of end surfaces 20 a along the longitudinal direction of the light guide plate 20. In addition, the light source unit 15 may be provided on at least one of the pair of end surfaces 20 a along the short direction of the light guide plate 20. Here, the longitudinal direction of the light guide plate 20 is the X direction, and the short direction is the Y direction. A direction perpendicular to both the X direction and the Y direction is taken as a Z direction. It can be said that the Z direction is a normal direction of the light guide plate 20. In the light guide plate 20, the direction from the end face 20 a on which light from the LED 12 enters to the end face 20 a on the opposite side to the end face is referred to as a “light guide direction”. Since the light source module 10 is provided on the end surface 20a along the longitudinal direction of the light guide plate 20, the “light guide direction” is the short direction (Y direction).

(Configuration of light source module)
FIG. 3 is a cross-sectional view schematically showing the configuration of the light guide plate 20 that is a characteristic part of the light source module 10. Here, the light guide plate 20 in the light source module 10 of the present embodiment includes a leading light portion 21 and a sub light guide portion 22 as shown in FIG. 3. The main light guide 21 has an exit surface 20b. And the shape of the back surface 21c on the opposite side to the output surface 20b in the main light part 21 is a plurality of streak-like uneven bodies T. Specifically, the plurality of streak-like concavo-convex shapes T are formed by arranging a plurality of prismatic structures each having a trapezoidal prism whose cross-sectional shape in the YZ direction is a trapezoid. The uneven body T is formed as a streak pattern on the back surface 21c, for example, along a direction (X direction) perpendicular to the light guide direction (Y direction). That is, the main light portion 21 has a plurality of concave and convex shaped bodies T formed of trapezoidal prisms having ridge lines parallel to the longitudinal direction on the back surface 21c opposite to the emission surface 20b.

  In addition, this uneven | corrugated shaped body T is a structure formed in the back surface 21c itself of the main light part 21, and is not provided in the main light part 21 as a member different from this main light part 21. FIG.

  The concavo-convex shape body T formed in the main light guide portion 21 is a shape having a function of raising light propagating through the main light portion 21, and is, for example, a prism shape. The light propagating through the main light guide portion 21 rises with respect to the emission surface 20b due to the concavo-convex shape. For this reason, the light extraction efficiency is improved. It can be said that the concavo-convex shape body T is an optical path conversion unit that converts the direction of the optical path of light propagating while being totally reflected in the main light unit 21 to the normal direction of the light guide plate 20.

  In the light source module 10, it is necessary to propagate light from the end face 20a on which the light from the LED 12 is incident to the end face 20a opposite to the end face. For this reason, when the light guide plate 20 is large (for example, 60 type) and the dimension in the light guide direction (Y direction) is large, the light extraction efficiency is lowered in the vicinity of the end face 20a where the light from the LED 12 is incident, It is necessary to increase the light extraction efficiency at a position where the distance in the light guide direction is long from the end face 20a where the light enters.

  In the light source module 10, the concavo-convex shaped body T is formed as a streak pattern along the direction (X direction) perpendicular to the light guide direction (Y direction) on the back surface 21c. In such a configuration, the density (groove density) of the concavo-convex shaped body T is lowered in the vicinity of the end face 20a where the light is incident, and the density of the concavo-convex shaped body T at a position far from the end face 20a where the light is incident in the light guide direction. The luminance distribution of the entire light guide plate 20 can be improved by increasing. For this reason, there is an advantage that the luminance distribution can be improved with a simple structure in which the density of the uneven shape body T is changed.

  Actually, when the light guide plate 20 is large (for example, 60 type), it is difficult to reduce the density of the concavo-convex shaped body T for the following reason.

  When the light guide plate 20 is large, it is desirable that the concavo-convex shaped bodies T ... are formed by extrusion from the viewpoint of cost reduction. In this case, there is a limit to the miniaturization of the uneven shape bodies T..., And it is difficult to reduce the size of each uneven shape body T. In addition, if the size of each of the concavo-convex shapes T is too small, when the light guide plate 20 expands due to heat generated from the LED 12, the concavo-convex shape T is crushed and the light extraction amount by the concavo-convex shape T Will change. From the above, it is difficult to reduce the size of each of the concavo-convex shaped bodies T.

  In addition, in order to reduce the density of the concavo-convex shape bodies T in a state where the size of the concavo-convex shape bodies T is large, it is necessary to increase the interval between the concavo-convex shape bodies T. In this case, the luminance distribution cannot be made uniform, and there is a problem that the quality is lowered, for example, the interval between the concavo-convex shaped bodies T is visually observed as luminance unevenness.

Therefore, in the light source module 10, the sub light guide portion 22 is provided on the back surface 21 c of the main light portion 21 and is configured to fill a gap between the concavo-convex shapes T. The light source module 10 has the following formula (1) when the light refractive index of the main light portion 21 is n1, the light refractive index of the sub light guide portion 22 is n2, and the light refractive index of the atmosphere is n0.
n1>n2> n0 (1)
It is the composition which satisfies.

  The light source module 10 is configured such that the sub light guide unit 22 fills the gap between the concavo-convex shaped bodies T formed in the main light unit 21. That is, the light guide plate 20 has a two-layer structure including a main light portion 21 and a sub light guide portion 22, and the main light portion 21 and the sub light guide portion 22 are interfaces of the concavo-convex shape body T. Are in close contact with each other. Moreover, the sub light guide part 22 is comprised with the material whose light refractive index is lower than the main light part 21, and whose light refractive index is higher than air | atmosphere. By adopting such a configuration, it is possible to suppress the improvement of the light extraction efficiency by the concavo-convex shape body T and reduce the light extraction efficiency while maintaining the light rising effect by the concavo-convex shape body. As a result, the density of the uneven shape body T can be lowered even if the size of the uneven shape body T is large, and thus the luminance distribution can be optimized. At the same time, light can be raised perpendicular to the emission surface 20b. Therefore, according to the configuration of the light source module 10, it is possible to achieve both optimization of the luminance distribution in the emission surface 20b and improvement in the luminance of light in the vertical direction (relative to the emission surface 20b). Hereinafter, the action and effect of the light source module 10 will be described in detail with reference to FIGS. FIG. 4 is a schematic diagram for explaining the operation and effect of the light source module 10. FIG. 4A shows the vicinity of the concavo-convex shape body T of the main light portion 21 when the sub light guide portion 22 is provided. FIG. 4B shows an optical path of the propagation light in the vicinity of the concavo-convex shape T of the main light portion 21 when the sub light guide portion 22 is not provided.

  As shown in FIG. 4A, the light A propagating through the main light unit 21 is divided into a reflection component B that is reflected and rises at the interface of the concavo-convex shape body T and a transmission component C that is transmitted through the concavo-convex shape body T. . The reflection component B is extracted at the exit surface 20b by the prism effect of the concavo-convex shaped body T. The traveling direction of the transmission component C is bent by refraction at the interface of the concavo-convex shaped body T. The transmissive component C whose traveling direction is bent is reflected at the interface between the sub light guide 22 and the atmosphere, that is, the lower side of the light guide plate 20, and is transmitted again through the interface between the sub light guide 22 and the main light 21. If the refractive index of the sub light guide part 22 is a value sufficiently close to the refractive index of the main light part 21, the effect of bending the traveling direction due to refraction is reduced, and the incident angle of the light A with respect to the lower side of the light guide plate 20 is light. Since the transmission angles at which C undergoes total reflection and transmits again through the main light part 21 side become substantially equal, the light C propagates through the main light part 21 while being totally reflected by the emission surface 20b while satisfying the total reflection condition. .

  In the configuration shown in FIG. 4A, the gap between the concavo-convex shaped bodies T formed in the main light portion 21 is filled with the sub light guide portion 22 having a light refractive index lower than that of the main light portion 21. Therefore, the reflection component B can be reduced. Further, the transmissive component C propagates again through the main light unit 21 through total reflection at the lower side of the light guide plate 20. For this reason, it is possible to suppress the improvement of the light extraction efficiency by the concavo-convex shape body T and to lower the light extraction efficiency while maintaining the light rising effect by the concavo-convex shape body.

  In addition, as shown in FIG. 4B, when the sub light guide 22 is not provided, the light A propagating through the main light 21 is reflected by the interface of the concavo-convex shape body T and rises. And a transmissive component C ′ that passes through the concavo-convex shaped body T. The reflection component B is extracted at the exit surface 20b by the prism effect of the concavo-convex shaped body T. The configuration of FIG. 4B has a larger light intensity of the reflection component B because the difference in refractive index between the main light portion 21 and the concavo-convex shape body T is larger than the configuration of FIG. The traveling direction of the transmission component C ′ is bent by refraction at the interface between the concavo-convex shaped body T and the atmosphere. The refracted transmission component C ′ is reflected by the reflection sheet 11, and then re-refracted at the interface between the sub light guide unit 22 and the main light unit 21, and then enters the main light unit 21 again. At this time, since the light refractive index n0 of the atmosphere is smaller than the light refractive index n2 of the sub light guide unit 22, the transmission angle at which the transmission component C passes through the main light body again after being refracted twice is the sub-angle of the light A. The incident angle to the light guide portion 22 is larger than that, and the transmissive component C is emitted from the emission surface 20b after breaking the total reflection condition after entering the main light portion 21.

  In addition, the reflection on the reflection sheet 11 in FIG. 4B is different in incident angle and reflection angle on the reflection surface compared to ideal total reflection at the interface of objects having different refractive indexes in FIG. Such light scattering components tend to increase. Among the light scattering components, the light component scattered at an angle that does not satisfy the total reflection condition on the exit surface 20b of the main light portion 21 is incident on the main light portion 21 and then is emitted from the output surface 20b after breaking the total reflection condition. Due to these effects, the configuration of FIG. 4B has a higher light emission rate than the configuration of FIG. 4A. The improvement in light extraction efficiency by the body T cannot be suppressed.

  FIG. 5 shows the light intensity distribution in the light guide direction (Y direction) of the exit surface 20b of the light source module 10 when the sub light guide 22 is provided and when the sub light guide 22 is not provided. It is a graph. The graph of FIG. 5 shows a concavo-convex shape body using a light guide plate 20 having a light guide direction (Y direction) dimension of 200 mm in both cases with and without the sub light guide 22. The pitch of T ... (center-to-center distance) is 1 mm.

  As shown in the graph of FIG. 5, when the sub light guide 22 is not provided, the light extraction efficiency at the position in the vicinity of the end surface 20 a where the light from the LED 12 enters is extremely high in the light guide direction of the light guide plate 20. Is getting bigger. On the other hand, when the sub light guide part 22 is provided, it turns out that the luminance distribution is uniform in the light guide direction of the light guide plate 20.

  In the distribution in the case where the sub light guide portion 22 is not provided (dotted line distribution), it is difficult to make the luminance uniform in the light guide direction of the light guide plate 20 or to realize a symmetrical distribution having the maximum intensity at the center. is there. When the intensity of the emitted light is made uniform in the light guide direction of the light guide plate 20 only by the uneven shape body T... Of the main light portion 21 without providing the sub light guide portion 22, is the pitch of the uneven shape body T increased? Alternatively, it is necessary to reduce the size of the uneven shape body T. However, when the light guide plate 20 is large (for example, 60 type), the uneven shape body T needs to have a dimension on the order of 1 μm in order to make the luminance uniform, and the light guide plate 20 having the uneven shape body T of such a size. Is not feasible for mass production.

  Next, the setting of the light refractive index n1 of the main light unit 21 and the light refractive index n2 of the sub light guide unit 22 will be described in detail. If the light refractive index n2 of the auxiliary light guide unit 22 is the same as the optical refractive index n1 of the main light unit 21, the light guide plate 20 has an uneven shape T at the interface between the main light unit 21 and the auxiliary light guide unit 22. It can be considered that it is a single piece without. In this case, the light propagating through the main light portion 21 does not change in angle due to reflection and refraction at the concavo-convex shaped body T interface, and ideally the light extraction efficiency is zero. From this, when the light refractive index n2 of the auxiliary light guide unit 22 is a value close to the light refractive index n1 of the main light unit 21, the light extraction efficiency is close to 0 and close to the atmospheric light refractive index n0. In the case of the value, it can be seen that the light extraction efficiency is close to the case where the sub light guide 22 is not provided.

Considering this point, the light refractive index n1 of the main light portion 21 and the light refractive index n2 of the auxiliary light guide portion 22 are expressed by the following equations (2) and (3).
n1-n2> 0.05 (2)
n2-n0> 0.30 (3)
It is preferable to satisfy.

  FIG. 6 shows the difference in optical refractive index n1-n2 and n2-n0 when the length in the light guide direction is 200 mm, the pitch of the concavo-convex shape body T is 1.0 mm, and the material of the main light portion is acrylic resin. It is a graph which shows the correlation with light extraction efficiency (the main light part side and the sub light guide part side). Here, FIG. 6 is a graph showing a simulation result obtained by approximating the light refractive index n0 of the atmospheric air to 1.0 while setting the light refractive index n1 of the main light portion made of acrylic resin to 1.5. For this reason, the optical refractive index difference n1-n0 is 0.5, which is a constant value. Therefore, when the value of the optical refractive index difference n1-n2 is determined, the optical refractive index difference n2-n0 is also uniquely determined.

  As shown in the graph of FIG. 6, when the optical refractive index difference n1-n2 is 0.05 or less (region A in FIG. 6), the light extraction efficiency is less than 20%, and the light extraction efficiency is deteriorated. Further, the fluctuation of the light extraction efficiency becomes larger with respect to the fluctuation of the optical refractive index difference n1-n2. For this reason, the influence of the emission characteristic of the module on the deviation of the optical refractive indexes n1 and n2 becomes large.

  Further, when the optical refractive index difference n1-n2 is 0.2 or more (region C in FIG. 6), the amount of light emitted from the main light portion is almost saturated, while the amount of light emitted from the sub light guide portion is It continues to increase. Therefore, since the amount of light emitted from the main light unit whose directivity is controlled is relatively small, the emission characteristic as a module is deteriorated.

  From the above, the preferable range of the optical refractive index difference n1-n2 is the region B shown in FIG. 6, which is more than 0.05 and less than 0.2 (0.05 <n1-n2 <0.2). is there. Moreover, the preferable range of the optical refractive index difference n2-n0 is more than 0.3 and less than 0.45 (0.3 <n2-n0 <0.45) from the graph of FIG.

  Further, the uneven height H of each uneven shaped body T is preferably 0.3% or more of the thickness D of the light guide plate 20. If the uneven height H of each uneven shape body T is less than 0.3% of the thickness D of the light guide plate 20 and the size of each uneven shape body T is too small, the heat generated from the LED 12 When the light guide plate 20 expands, the concavo-convex shape body T is crushed. For this reason, the light extraction amount by the concavo-convex shaped body T changes. In the light source module 10, the uneven height H of each uneven shape body T is 0.3% or more of the thickness D of the light guide plate 20, and even if the uneven shape body T is enlarged, It is possible to optimize the luminance distribution by the action. In the present embodiment, the thickness of the main light portion 21 is overwhelmingly larger than the thickness of the sub light guide portion 22, that is, “thickness of the main light portion 21” ≈ “thickness of the light guide plate 20”. Is assumed. However, the present invention is not limited to this. For example, a configuration in which the thickness of the sub light guide unit is the same as or larger than the thickness of the main light unit due to the influence of thermal expansion due to heat generation can be assumed. Even in such a case, the uneven height H of each uneven shaped body T is preferably 0.3% or more of the thickness D of the light guide plate 20.

  The length of the light guide plate 20 in the light guide direction is specifically 300 mm or more. In the light source module 10, even if a large light guide plate with a long light guide distance is used, the density of the concavo-convex shaped body T is reduced in the vicinity of the end face 20 a on which light is incident, and the light is guided from the end face 20 a on which light is incident. The density of the concavo-convex shaped body T at a position far from the direction can be increased. As a result, the luminance distribution can be optimized.

  The shape of the concavo-convex shape body T is not limited to the prism shape as long as it has a function of raising the light propagating through the main light portion 21. For example, as shown to Fig.7 (a), it becomes cylinder shape, such as cross-sectional arc shape or circular arc shape. When the thickness of the light guide plate 20 is the same, the shape shown in FIG. 7A can easily ensure a larger cross-sectional area than the prism shape described later. As a result, in the configuration in which the concavo-convex shape body T having a semicircular cross section is formed on the back surface 21c of the main light portion 21, the light coupling efficiency at the light incident surface from the LED 12 is high, and light leakage hardly occurs. Such a shape can be formed by extruding the light guide plate 20.

  Here, the structure of the concavo-convex shape body T is not necessarily the cylinder shape such as the cross-sectional arc shape or the arc shape shown in FIG. 7A, but the shape shown in FIGS. 7B, 7C, and 7D. Is also possible.

  The concave-convex shaped body T shown in FIG. 7B is formed by forming a prism with an apex angle of 90 ° on the back surface 21 c of the main light portion 21. The concave / convex shaped body T shown in FIG. 7C is formed by forming a prism with an apex angle of 5 ° on the back surface 21 c of the main light portion 21. 7D has a structure having a concave cylinder surface that is recessed with respect to the back surface 21c of the main light portion 21. The concave-convex shape body T shown in FIG.

  In the above example, the light source module 10 is applied to the liquid crystal display device 1. However, the electronic device to which the light source module 10 can be applied is not limited to the liquid crystal display device. For example, the light source module 10 may be applied to a lighting device. The illumination device including the light source module 10 can be used as an illumination device for illuminating the room or the outdoors. For example, there is use as surface illumination of the light guide plate 20 that is assumed to be incorporated in a door or the like.

  The light source module 10 can be applied to an information display device provided in, for example, an advertisement panel, a signboard, a sign panel, a guide panel, or a poster panel. FIG. 8 is a cross-sectional view showing the overall configuration of the information display device 1A including the light source module 10.

  As shown in FIG. 8, in the information display device 1A, the chassis 7, the light source module 10, the optical sheet 6, and the information display unit 8 are arranged in this order from the bottom. The cover 5 is a member for housing the chassis 7, the light source module 10, the optical sheet 6, and the information display unit 8.

  The information display unit 8 is made of a member for displaying a stationary design such as a character or a picture. Specifically, it is a member that displays a design such as an advertisement, a signboard, a sign, a guide map, or a poster, for example, and includes a display unit by drawing or the like by direct application to the light source module 10. The information display unit 8 is made of paper, transparent resin, translucent resin, opaque resin, metal or the like. By irradiating light from the back surface with the light emitted from the optical sheet 6, the information display unit 3 can be displayed brightly regardless of day or night. Therefore, the information display device 1A can be applied as, for example, an advertisement panel, a signboard, a sign panel, a guidance panel, or a poster panel by displaying on the information display unit 8.

  The present invention is not limited to the above-described embodiment, and various modifications are possible within the scope shown in the claims, and the present invention is also applied to an embodiment obtained by appropriately combining technical means disclosed in the embodiment. It is included in the technical scope of the invention.

  The present invention relates to a light source module including a side edge (also referred to as sidelight) type light guide plate that emits light from a light source in a planar shape by a light guide plate, and an electronic device including the same, for example, a backlight. It is applicable to electronic devices such as a light source module such as a liquid crystal display device and a lighting device.

1 Liquid crystal display device (electronic equipment)
10 Light source module 12 LED (light source)
20 Light guide plate 20a End face 20b Outgoing face 20c Lower face (surface)
21 Main light guide part 21c Back surface 22 Sub light guide part T Uneven shape body (uneven shape)

Claims (7)

A light source module comprising: a light guide plate that emits light incident in a direction perpendicular to the end surface from at least one of a pair of opposed end surfaces; and a plurality of light sources that emit light to the light guide plate,
The light guide plate is composed of a leading light portion having the exit surface and a concavo-convex shape formed on the back surface opposite to the exit surface, and a sub light guide portion filling a gap between the concavo-convex shapes,
When the light refractive indexes of the main light portion, the sub light guide portion, and the atmosphere are n1, n2, and n0, the following formula (1)
n1>n2> n0 (1)
A light source module characterized by satisfying Following formula (2) and (3)
n1-n2> 0.05 (2)
n2-n0> 0.30 (3)
The light source module according to claim 1, wherein: When the direction perpendicular to the end face of the light guide plate is the first direction,
3. The light source module according to claim 1, wherein the uneven shape on the back surface is a streak shape extending in a direction perpendicular to the first direction. 4. When the uneven height of the uneven shape is H and the thickness of the light guide plate is D,
The light source module according to any one of claims 1 to 3, wherein the uneven height H is 0.3% or more of a thickness D of the light guide plate. When the direction perpendicular to the end face of the light guide plate is the first direction,
The length of the said 1st direction in the said light-guide plate is 300 mm or more, The light source module of any one of Claims 1-4 characterized by the above-mentioned.   A liquid crystal display device comprising the light source module according to claim 1.   The illuminating device provided with the light source module of any one of Claims 1-5.

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