JP2009176593A - Lighting device and display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To restrain uneven light intensity emitted from a light-emitting surface of a light guide plate, using a simple structure. <P>SOLUTION: A illumination device 1 comprises the light guide plate 2 for emitting light incident from a light-incident surface from a light-exiting surface, by reflecting with a V-shaped groove 27 arranged at a lower surface, and spot light sources 4-1, 4-2, and 4-3 arranged on the light-incident surface. Grooves 3-1, 3-2, with curved surfaces wherein the moving direction of the incident light from the light-incident surface to an opposite surface is approached in a direction orthogonal to the light-incident surface, are formed on the light-exiting surface of the light guide plate 2. The light incident from the light-incident surface moves by gradually approaching in the direction orthogonal to the light-incident surface so that the light incident from the light-incident surface repeats reflection to the grooves 3-1, 3-2. Then, the light with high directivity vertical to the light-exiting surface is generated with reflection of the V-shaped groove 27. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an illumination device for performing liquid crystal display and the like, and a display device using the illumination device.

  A liquid crystal display device used for a cellular phone or the like uses a member that absorbs light such as a deflecting plate or a color filter, and therefore, the display becomes dark only by reflected light of natural light. For this reason, in order to brighten the display of the liquid crystal display device, an illumination device such as a backlight is disposed on the back surface of the liquid crystal display device so that light is emitted from the illumination device to the liquid crystal display device.

  FIG. 8 is an external view showing a configuration of a conventional lighting device. FIG. 9 is a cross-sectional view of the lighting device shown in FIG. This illuminating device uses an edge light system (side light system) in which light enters from the side surface and exits from the upper surface, and includes a Y-direction prism sheet 21, an X-direction prism sheet 22, a diffusion plate 23, a light guide plate 24, and a reflection. A plate 25 is provided hierarchically, and a line light source 26 is provided along one side of the side surface of the light guide plate 24.

  The light guide plate 24 is made of a transparent material such as acrylic, and receives light from the line light source 26 through the light incident surface. A plurality of V-shaped grooves 27 are formed on the lower surface of the light guide plate 24 to scatter light incident from the light incident surface upward (in the positive direction of the Z axis). The light source 26 includes a light emitting element, and an LED (Light Emitting Diode) is used as the light emitting element.

  The diffusion plate 23 is provided above the light guide plate 24 and scatters light emitted at a shallow angle from the light exit surface of the light guide plate 24 in the vertical direction. Thereby, luminance unevenness due to the light reflected on the V-shaped groove 27 of the light guide plate 24 can be suppressed.

  The X-direction prism sheet 22 is provided above the diffusing plate 23, and a large number of sawtooth prisms are formed in the Y-axis direction on the surface thereof, and light having an angle in the Y-axis direction is vertically directed. Turn. The Y-direction prism sheet 21 is provided on the upper side facing the X-direction prism sheet 22, and a large number of sawtooth prisms are formed in the X-axis direction on the surface, and light having an angle in the X-axis direction is perpendicular to the Y-direction prism sheet 21. Turn in the direction.

  The reflection plate 25 is provided below and facing the light guide plate 24, and scattered light that has been scattered through the outside from the lower surface of the light guide plate 24 is incident on the inside from the lower surface of the light guide plate 24 again. Emits upward from the surface.

  In FIG. 9, an arrow indicates light that enters the light guide plate 24 from the line light source 26 and finally exits upward via the Y-direction prism sheet 21. The light passes through the inside while being totally reflected on the upper surface and the lower surface of the light guide plate 24 and proceeds in the positive direction of the X axis. When the light enters the inclined surface of the V-shaped groove 27 formed below the light guide plate 24, the light is totally reflected and goes upward depending on the incident angle, or passes through the V-shaped groove 27 to the outside atmosphere and is reflected by the reflective plate. The light is reflected by 25, re-enters the light guide plate 24, and moves upward. Therefore, the light emitted from the light exit surface of the light guide plate 24 is diffused, and is not necessarily directed to the positive direction of the Z axis that is the main illumination direction (the direction perpendicular to the light exit surface). That is, there is not only light perpendicular to the light exit surface but also light at a shallow angle with respect to the light exit surface.

  The liquid crystal display device that is irradiated with light from the lighting device 20 needs light having high directivity in the vertical direction. Therefore, in order to deflect such diffused light into light having high directivity in the vertical direction, a Y-direction prism sheet 21 and an X-direction prism sheet 22 are provided.

  However, in the illumination device 20 provided with the Y-direction prism sheet 21 and the X-direction prism sheet 22, the number of parts increases, the number of assembling steps increases, and the cost increases. Therefore, an illumination device is known in which the Y-direction prism sheet 21 and the X-direction prism sheet 22 are not required, and the prism sheet and the light guide plate are integrated (see Patent Document 1).

  FIG. 10 is a diagram showing a configuration of a light guide plate used in a conventional lighting device, and shows a configuration when the lower surface of the light guide plate is viewed from below. The light guide plate 31 is provided with a reflection layer 33 provided with a diffuse reflection pattern by a plurality of grooves 32 on the lower surface thereof, and a line light source 34 is provided along one side of the side surface. The grooves 32 are formed in parallel in the direction along the traveling direction of the light from the line light source 34 that passes through the inside of the light guide plate 31, that is, in the direction orthogonal to the light incident surface.

When light enters from the line light source 34 through the light incident surface and passes in a direction orthogonal to the light incident surface, the light is diffusely reflected by each groove 32 and emitted from the light output surface (upper surface). Since the irregular reflection action is uniform in each groove 32 and the change in luminance due to the distance from the line light source 34 is reduced, as a result, light with less luminance unevenness can be emitted from the light output surface of the light guide plate 31.
JP-A-8-29624

  The illumination device using the light guide plate 31 shown in FIG. 10 is a surface light source device in which a line light source 34 is disposed on one side of the side surface of the light guide plate 31. Here, when a plurality of point light sources are arranged at predetermined intervals instead of the line light source 34, light does not uniformly enter from the light incident surface of the light guide plate 31, and therefore the direction of light traveling in the light guide plate 31 is determined. Varies by location. For this reason, the irregular reflection effect is not uniform over the entire length of each groove 32, and light with uneven brightness is emitted from the light exit surface of the light guide plate 31. Even in an illumination device using such a point light source, the luminance unevenness of the light emitted from the light exit surface of the light guide plate 31 can be suppressed, the number of parts can be reduced as a whole, the number of assembling steps can be reduced, and the cost can be reduced. Is desirable.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to suppress luminance unevenness of light emitted from a light exit surface of a light guide plate with a simple configuration in an illumination device in which a light source is disposed on a side surface of the light guide plate and a display device using the light source. .

  In order to solve the above problems, the present invention has taken the following measures.

  (1) In a lighting device including a light source and a light guide plate that reflects light incident from the light source through a light incident surface by a reflection mechanism and emits the reflected light from the light output surface, the light guide plate includes: And a groove having a curved surface for making the direction in which the incident light travels approach the direction orthogonal to the light incident surface is formed on the light exit surface from the light incident surface toward the surface facing the light incident surface. did.

  (2) In the illumination device according to (1), the groove of the light guide plate has at least a part of a semicircular cross-sectional shape on a light incident surface and a cross-sectional shape on a surface facing the light incident surface. The semicircular diameter is formed so as to be closer to.

  (3) In the illumination device according to (1), the groove of the light guide plate has at least a part of a semicircular cross-sectional shape on a light incident surface and a cross-sectional shape on a surface facing the light incident surface. The semicircular diameter is formed to be smaller as it is closer to.

  (4) In the illumination device of (1), the groove of the light guide plate is formed from the light incident surface to the middle of the surface facing the light incident surface.

  (5) In the illuminating device according to (1), the light guide plate is configured so that the traveling direction of incident light approaches the direction orthogonal to the light incident surface from the light incident surface toward the surface facing the light incident surface. A plurality of grooves having a curved surface are formed in parallel.

  (6) In the illumination device of (1), the groove of the light guide plate is formed so that a cross-sectional shape parallel to the light incident surface has at least a part of a semicircular shape.

  (7) In the illumination device of (1), the groove of the light guide plate is formed so that the cross-sectional shape parallel to the light incident surface has at least a part of an ellipse.

  (8) In the illumination device of (6) or (7), the groove of the light guide plate is formed so that a cross-sectional shape parallel to the light incident surface has a linear shape.

  (9) In the illumination device of (1), one light source and the light guide plate in which one groove is formed are provided.

  (10) In any one of the illumination devices according to (1) to (8), the groove is formed on a light incident surface between the plurality of light sources and two light sources of the plurality of light sources. The light guide plate is provided.

  (11) In the lighting device according to any one of (1) to (10), the minimum distance between the groove and the surface facing the light output surface of the light guide plate is the light output surface of the light guide plate and the light output. It was made to be 0.2 to 0.8 times the distance between the surfaces facing the surface.

  (12) The display device includes any one of the illumination devices (1) to (11) and a display panel to which light emitted from the illumination device is irradiated.

  According to the present invention, the light guide plate has a groove having a curved surface for bringing the incident light traveling direction closer to a direction orthogonal to the light incident surface from the light incident surface toward the surface facing the light incident surface. , Formed on the light exit surface. The light incident from the light incident surface is gradually reflected in the groove, and gradually approaches the direction perpendicular to the light incident surface. Further, the farther from the light incident surface, the more such light is reflected by the reflection mechanism of the light guide plate, so that the light has a higher directivity in the direction perpendicular to the light exit surface. In other words, the closer to the light incident surface, the higher the luminance due to light from the light source, and the farther from the light incident surface, the higher the luminance due to light having high directivity in the vertical direction. Therefore, uneven brightness of light emitted from the light exit surface of the light guide plate can be suppressed over the entire light exit surface. Further, since a prism sheet is not required, a simple configuration can be realized, the number of parts can be reduced, the number of assembling steps can be reduced, and the cost can be reduced.

  Hereinafter, the best mode for carrying out the present invention will be described in detail with reference to the drawings. An embodiment of the present invention relates to a lighting device including a light guide plate that emits light incident from a side surface to the outside from an upper surface, and one or more point light sources arranged on one side of the side surface of the light guide plate. The light incident from the light incident surface is deflected in a direction substantially orthogonal to the light incident surface, reflected by a V-shaped groove provided on the lower surface of the light guide plate, and emitted in a direction substantially orthogonal to the light output surface of the light guide plate. Features. Specifically, a groove having a curved surface in a direction perpendicular to the light incident surface is formed on the light guide plate, and light incident from the light incident surface is repeatedly reflected on the curved surface of the groove, so that the light traveling direction is made incident. Move closer to the direction perpendicular to the surface. And it reflects on the inclined surface of the V-shaped groove formed on the lower surface of the light guide plate, thereby generating light having high directivity with respect to the light exit surface.

  As a result, luminance unevenness of light emitted from the light exit surface of the light guide plate can be suppressed, so that the Y-direction prism sheet 21 and the X-direction prism sheet 22 shown in FIGS. 8 and 9 are not necessary. Further, since the lighting device has a simple configuration, the number of parts can be reduced as a whole, the number of assembling steps can be reduced, and the cost can be reduced.

  FIG. 1 is an external view illustrating a configuration of a light guide plate provided in a lighting device according to an embodiment of the present invention. The illuminating device 1 includes a light guide plate 2 and point light sources 4-1, 4-2, 4-3. Two grooves 3-1 and 3-2 are formed on the upper surface (light exit surface) of the light guide plate 2. The point light sources 4-1, 4-2, and 4-3 are made of, for example, LEDs, and are provided at predetermined intervals along one side (light incident surface) of the side surface of the light guide plate 2.

  A diffusion plate (not shown) is provided above the light guide plate 2 in parallel with and opposite to the light guide plate 2, and below the light guide plate 2 in parallel with and opposite to the light guide plate 2. A reflector (not shown) is provided. Since the diffusing plate and the reflecting plate have been described above, description thereof will be omitted.

  The grooves 3-1 and 3-2 formed on the upper surface of the light guide plate 2 are semicircular in a cross section parallel to the light incident surface of the light guide plate 2, and the light guide plate 2 is directed toward the positive side of the Y axis. It has a concavely curved surface. The groove 3-1 extends vertically from the light incident surface between the point light sources 4-1 and 4-2 to the surface facing the light incident surface toward the positive side of the Y axis. Similarly, the groove 3-2 extends vertically from the light incident surface between the point light sources 4-2 and 4-3 to the surface facing the light incident surface toward the positive side of the Y axis.

  On the lower surface of the light guide plate 2, as shown in FIG. 9, a light reflecting surface composed of a plurality of V-shaped grooves 27 provided at predetermined intervals is formed. The V-shaped groove 27 has a function of deflecting light incident from the light incident surface upward (in the positive direction of the Z axis). In particular, when light orthogonal to the light incident surface is reflected by the inclined surface of the V-shaped groove 27, it can be emitted from the light output surface as light substantially orthogonal to the light output surface, that is, light having high directivity in the vertical direction. . The inclined surface of the V-shaped groove 27 is provided to face the light incident surface, and the angle between the inclined surface and the XY plane that is the lower surface of the light guide plate 2 is preferably 40 to 50 degrees.

  FIG. 2 is a top view of the light guide plate 2 for explaining the direction of light that travels reflected by the grooves 3-1 and 3-2 of the light guide plate 2. FIG. 3 is a cross-sectional view of the light guide plate 2 for explaining the reflection of light with respect to the direction parallel to the light incident surface of the grooves 3-1 and 3-2 of the light guide plate 2. In FIG. 2, the light in the XY plane incident from the light incident surface of the light guide plate 2 is reflected by the curved surfaces of the grooves 3-1 and 3-2, so that the direction perpendicular to the light incident surface (the positive direction of the Y axis). ) To a shallow angle (θ1> θ2). By repeating such reflection, the light traveling direction is aligned with the direction orthogonal to the light incident surface, that is, the positive direction of the Y axis. This is because the light incident on the curved surfaces of the grooves 3-1 and 3-2 is dispersed and reflected in the lower surface direction of the light guide plate 2 as shown in FIG. Referring to FIG. 2, the reflection angle θ2 of light in the XY plane that is incident at the incident angle θ1 is dispersed between the angles + θ1 and −θ1. That is, the reflected light reflected by the curved surfaces of the grooves 3-1 and 3-2 is gradually aligned in the positive direction of the Y axis when reflection is repeated.

  Temporarily, when the groove | channel which consists of two planes is formed instead of the groove | channels 3-1 and 3-2 which have a curved surface, ie, the cross section parallel to the light-incidence surface of the light-guide plate 2 is a triangular hollow. Suppose that a groove having a triangular recess is formed by two planes facing the positive side of the Y axis. In this case, since the light is emitted at the same angle as the incident angle even if it is reflected on the plane of the groove, this angle is maintained even if the reflection is repeated. Therefore, the light traveling direction is not gradually aligned in the direction orthogonal to the light incident surface, that is, the Y-axis direction.

  Thus, the light incident on the light guide plate 2 from the point light sources 4-1, 4-2, 4-3 through the light incident surface repeats the reflection of the curved surfaces of the grooves 3-1, 3-2. The tendency to proceed in the direction orthogonal to the light incident surface is increased. Then, such light is reflected by the inclined surface of the V-shaped groove 27 and is efficiently emitted from the light exit surface as light having high directivity in the vertical direction, and becomes light with a narrow viewing angle.

  In FIG. 1, the light emitted from the light exit surface of the light guide plate 2 has a higher brightness as it is closer to the light entrance surface, and has a lower brightness as it is farther from the light entrance surface. On the other hand, since the number of reflections on the curved surfaces of the grooves 3-1 and 3-2 increases as the distance from the light incident surface increases, the directivity in the direction orthogonal to the light incident surface increases, and the light is reflected on the V-shaped groove 27. By doing so, the directivity in the vertical direction increases. Thereby, the light emitted from the light exit surface of the light guide plate 2 has less luminance unevenness as the entire light exit surface. Further, since the light emitted from the light exit surface of the light guide plate 2 has high directivity in the vertical direction, the diffused light is polarized into light having high directivity in the vertical direction as shown in FIGS. The Y-direction prism sheet 21 and the X-direction prism sheet 22 are not necessary.

  Therefore, the illumination device 1 suppresses uneven luminance of light emitted from the light exit surface of the light guide plate 2 with a simple configuration even when the point light sources 4-1, 4-2, 4-3 are used. As a whole, it is possible to reduce the number of parts, reduce the number of assembly steps, and reduce the cost. Moreover, it can comprise thinly as the illuminating device 1 whole. Further, due to the shapes of the grooves 3-1 and 3-2 formed on the upper surface of the light guide plate 2 and the V-shaped groove 27 formed on the lower surface, the amount of light having high directivity in the vertical direction as light emitted from the light exit surface and Since the amount of diffused light can be adjusted, an optimal light flux distribution applicable to the display device can be generated.

  FIG. 4 is a diagram illustrating examples of dimensions of the groove 3-1 and the point light sources 4-1, 4-2 of the light guide plate 2. The same applies to the groove 3-2 and the point light source 4-3. The distance A between the upper surface and the lower surface, which is the light output surface of the light guide plate 2, is 0.5 to 4 mm. Between the curved surface of the groove 3-1 closest to the lower surface of the light guide plate 2 and the lower surface of the light guide plate 2. The distance B is a value from 0.2 times to 0.8 times the distance A.

  The distance C between the point light sources 4-1 and 4-2 is 4 to 20 mm, and the width D of the point light sources 4-1 and 4-2 is 3 mm. In this case, the point light sources 4-1 and 4-2 and the groove 3-1 are formed on the extended line of one side of the point light sources 4-1 and 4-2, It is desirable that the boundary points “a” and “b” exist between the two. This is because the light incident on the light incident surface from the point light sources 4-1 and 4-2 can efficiently reflect the curved surface of the groove 3-1.

  FIG. 5 is an external view showing a configuration of a display device using the illumination device according to the embodiment of the present invention. The display device 10 is configured to include a liquid crystal display panel 11, a diffusion plate 12, a light guide plate 2, and a reflection plate 13 in a hierarchical manner, and point light sources 4-1, 4-2, 4 on one side of the light guide plate 24. -3 is provided. The illuminating device 1 shown in FIG. 1 includes a diffusing plate 12 (not shown in FIG. 1), a light guide plate 2, a reflecting plate 13 (not shown in FIG. 1), and dots among the components of the display device 10. It corresponds to the light sources 4-1, 4-2 and 4-3. That is, the display device 10 includes a liquid crystal display panel 11 in addition to the illumination device 1 shown in FIG. 1. For example, a mobile phone, a PND (Personal Navigation Device), a smartphone, a notebook PC, and a simple portable type. Used for car navigation systems.

  The liquid crystal display panel 11 is provided in parallel to the diffusion plate 12 and facing the upper side of the diffusion plate 12. The liquid crystal display panel 11 includes a liquid crystal panel in which two glass substrates are bonded to each other with a predetermined gap by a sealing material, and a liquid crystal layer is formed in the gap, and an upper polarizing plate and a lower polarizing plate attached to the outer surface of the liquid crystal panel. It consists of and.

  Thus, since the display device 10 is configured to include the illumination device 1 shown in FIG. 1, the directivity in the vertical direction is high from the light exit surface of the light guide plate 2 through the diffusion plate 12, and the luminance is high. Light with less unevenness irradiates the lower surface of the liquid crystal display panel 11. As a result, the display device 10 can realize display with high luminance and less luminance unevenness over the entire display surface. Further, since the Y-direction prism sheet 21 and the X-direction prism sheet 22 as shown in FIGS. 8 and 9 are not necessary, the number of parts is reduced as a whole of the display device 10 by a simple configuration, and the number of assembling steps is reduced. Costs can be reduced. Further, the display device 10 as a whole can be made thin.

  FIGS. 6A to 6D are external views showing configurations of light guide plates 2a, 2b, 2c, and 2d provided in a lighting device 1 according to another embodiment. The four types of light guide plates 2a, 2b, 2c, 2d shown in FIGS. 6A to 6D are provided with three point light sources 4-1, 4-2, 4-3 on one side of the side surface. However, the shapes of the grooves 3a-1, 3a-2, grooves 3b-1, 3b-2, grooves 3c-1, 3c-2, and grooves 3d-1, 3d-2 formed on the upper surface are the same. It is different in different points.

  The grooves 3a-1 and 3a-2 of the light guide plate 2a shown in FIG. 6A are in a cross-section parallel to the light incident surface of the light guide plate 2a. It has a curved surface that is recessed in a concave shape toward the surface facing the light incident surface. In other words, the radius from the light incident surface to the surface facing the surface gradually decreases from the maximum diameter, and the surface facing the light incident surface has a minimum diameter.

  According to the light guide plate 2a of FIG. 6A, the closer to the light incident surface, the larger the radii of the grooves 3a-1 and 3a-2. Therefore, the number of times of light reflection increases, and the directivity in the direction orthogonal to the light incident surface It becomes light with higher nature. Then, the light reflected by the V-shaped groove 27 becomes light having higher directivity in the vertical direction, and the luminance of light emitted from the light exit surface of the light guide plate 2 is further increased. In addition, since the light guide plate 2a has the maximum radius of the grooves 3a and 3b on the light incident surface, the distance between the point light sources 4-1, 4-2 and 4-3 provided on one side of the side surface of the light guide plate 2a. It becomes effective when is long.

  The grooves 3b-1 and 3b-2 of the light guide plate 2b shown in FIG. 6 (b) have a semicircular shape with a smaller radius toward the light entrance surface in a cross section parallel to the light entrance surface of the light guide plate 2b. It has a curved surface that is recessed in a concave shape toward the surface facing the light incident surface. That is, the radius from the light incident surface to the surface facing the surface gradually increases from the minimum diameter, and reaches the maximum diameter on the surface facing the light incident surface.

  According to the light guide plate 2b of FIG. 6 (b), light is reflected on the curved surfaces of the grooves 3b-1 and 3b-2 formed on the upper surface thereof, and the reflection is repeated so that the light in the direction orthogonal to the light incident surface is obtained. Light with high directivity. And by reflecting in the V-shaped groove 27, it becomes light with high directivity in the vertical direction, and the luminance of light emitted from the light exit surface of the light guide plate 2b is increased. In addition, since the light guide plate 2b has the minimum radius of the grooves 3b-1 and 3b-2 on the light incident surface, the point light sources 4-1, 4-2 and 4- are provided on one side of the light guide plate 2b. This is effective when the distance between the three is small.

  The grooves 3c-1 and 3c-2 of the light guide plate 2c shown in FIG. 6C have a semicircular shape in a cross section parallel to the light incident surface of the light guide plate 2c, and are between the light incident surface and the opposing surface. It has a curved surface that is concave in the middle. That is, when the grooves 3-1 and 3-2 of the light guide plate 2 shown in FIG. 1 are compared with the grooves 3c-1 and 3c-2 of the light guide plate 2c shown in FIG. It is the same in that the cross section parallel to the optical surface is semicircular. On the other hand, the grooves 3-1 and 3-2 in FIG. 1 extend to the surface facing the light incident surface, whereas the grooves 3c-1 and 3c-2 in FIG. 6 are opposed to the light incident surface. It is different in that it extends only to the middle of the surface.

  According to the light guide plate 2c in FIG. 6 (c), light is reflected on the curved surfaces of the grooves 3c-1 and 3c-2 formed halfway along the surface facing the light incident surface, and the reflection is repeated. The light has high directivity in the direction orthogonal to the light surface. And by reflecting in the V-shaped groove 27, it becomes light with high directivity in the vertical direction, and the luminance of the light emitted from the light exit surface of the light guide plate 2c is increased.

  The grooves 3d-1-1, 3d-1-2, 3d-2-1 and 3d-2-2 of the light guide plate 2d shown in FIG. 6D are half in the cross section parallel to the light incident surface of the light guide plate 2d. It has a circular shape and has a curved surface that is recessed in a concave shape toward the surface facing the light incident surface. The two grooves 3d-1-1 and 3d-1-2 are provided between the point light sources 4-1 and 4-2 so as to be orthogonal to and parallel to the light incident surface. Similarly, the two grooves 3d-2-1 and 3d-2-2 are also provided between the point light sources 4-2 and 4-3 so as to be orthogonal to and parallel to the light incident surface. The grooves 3-1 and 3-2 of the light guide plate 2 shown in FIG. 1 and the grooves 3d-1-1, 3d-1-2, 3d-2-1 and 3d of the light guide plate 2d shown in FIG. When 2-2 is compared, they are the same in that the cross-sectional shape parallel to the light incident surface is a semicircular shape. On the other hand, only one of the grooves 3-1 and 3-2 in FIG. 1 is formed between the point light sources 4-1, 4-2 and 4-3, whereas the groove 3d in FIG. -1-1, 3d-1-2, 3d-2-1 and 3d-2-2 are different in that two are formed adjacent to each other in parallel.

  According to the light guide plate 2d shown in FIG. 6D, the grooves 3d-1-1, 3d-1-2, 3d-2-1 and 3d-2-2 are brought close to the point light sources 4-1 and 4-2. Can do. That is, the groove 3d-1-1 is a point light source 4-1, the groove 3d-1-2 is a point light source 4-2, the groove 3d-2-1 is a point light source 4-2, and the groove 3d-2-2. Can be brought close to the point light source 4-3, respectively. The point light sources 4-1, 4-2, 4-3 and the grooves 3d-1-1, 3d-1-2, 3d-2-1 and 3d-2-2 are as shown in FIG. On the extended line of one side of the point light sources 4-1, 4-2, 4-3, the plane on the upper surface of the light guide plate 2d and the grooves 3d-1-1, 3d-1-2, 3d-2-1, 3d-2. 2 so that the boundary point between the light sources 4-1 and 4-2 is incident on the light incident surface, the grooves 3d-1-1, 3d-1-2, The curved surfaces of 3d-2-1 and 3d-2-2 can be efficiently reflected.

  In addition, according to the light guide plate 2d of FIG. 6D, light is incident on the curved surfaces of the grooves 3d-1-1, 3d-1-2, 3d-2-1 and 3d-2-2 formed on the upper surface thereof. By reflecting and repeating the reflection, light having high directivity in the direction orthogonal to the light incident surface is obtained. And by reflecting in the V-shaped groove 27, it becomes light with high directivity in the vertical direction, and the luminance of light emitted from the light exit surface of the light guide plate 2d is increased.

  7A to 7D are views showing the cross-sectional shape of the groove 3 formed on the upper surface of the light guide plate 2. The groove 3x-1 shown in FIG. 7A has a semicircular cross-sectional shape, and has the groove shape described in the above embodiment. According to the groove 3x-1, the light incident from the light incident surface of the light guide plate 2 is reflected by the semicircular curved surface, thereby forming a shallow angle (θ1> θ2) with respect to the direction orthogonal to the light incident surface. Change the direction. By repeating such reflection, the light traveling direction becomes close to the direction orthogonal to the light incident surface. And it reflects in the V-shaped groove 27 formed in the lower surface of the light-guide plate 2, becomes light with high directivity of a perpendicular direction, and a brightness | luminance becomes high.

  The groove 3x-2 illustrated in FIG. 7B is configured by a part of a semicircular cross-sectional shape. According to the groove 3x-2, the ratio of the groove 3x-2 to the entire upper surface of the light guide plate 2 is smaller than that of the groove 3x-1 shown in FIG. When the light is emitted, the influence of the groove 3x-2 can be reduced, and the luminance unevenness is further reduced.

  The groove 3y shown in FIG. 7C has a semi-elliptical cross section. According to the groove 3y, the light incident from the light incident surface of the light guide plate 2 is reflected by the semi-elliptical curved surface, thereby forming a shallow angle (θ1> θ2) with respect to the direction orthogonal to the light incident surface. Change the direction. By repeating such reflection, the light traveling direction becomes close to the direction orthogonal to the light incident surface. And it reflects in the V-shaped groove 27 formed in the lower surface of the light-guide plate 2, becomes light with high directivity of a perpendicular direction, and a brightness | luminance becomes high. In addition, as shown in FIG.7 (b), the groove | channel 3y may be made to comprise a part with a semi-elliptical cross-sectional shape.

  The groove 3z-1 shown in FIG. 7D has a semicircular cross-sectional shape, and a semicircular bottom has a linear shape. According to the groove 3z-1, the light incident from the light incident surface of the light guide plate 2 is reflected on the curved surface of the groove 3z-1 as in the grooves 3x-1, 3x-2, and 3y described above. The direction is changed so as to be a shallow angle (θ1> θ2) with respect to the direction orthogonal to the light incident surface. By repeating such reflection, the light traveling direction becomes close to the direction orthogonal to the light incident surface. And it reflects in the V-shaped groove 27 formed in the lower surface of the light-guide plate 2, becomes light with high directivity of a perpendicular direction, and a brightness | luminance becomes high. In addition, the light incident from the light incident surface is reflected on the flat surface of the groove 3z-1 (where the cross-sectional shape forms a straight line), thereby being reflected on the planar portion of the upper surface or the lower surface of the light guide plate 2. So that it reflects at the same angle. As shown in FIG. 7 (b), the groove 3z-1 is configured by a part of a semicircular cross section, and a part of the bottom of the semicircular is formed by a straight line. May be. In addition, the groove 3z-1 has a cross-sectional shape as shown in FIG. 7C constituted by a semi-elliptical part or a semi-elliptical part, and a bottom part of the semi-elliptical or semi-elliptical part has a bottom. You may make it comprise a linear shape.

  The groove 3z-2 shown in FIG. 7E is configured by combining four parts having a semicircular cross-sectional shape, and the bottom has a linear shape. According to the groove 3z-2, the light incident from the light incident surface of the light guide plate 2 is reflected on the curved surface of the groove 3z-2 as in the grooves 3x-1, 3x-2, 3y, 3z-1 described above. By doing so, the direction is changed so as to be a shallow angle (θ1> θ2) with respect to the direction orthogonal to the light incident surface. By repeating such reflection, the light traveling direction becomes close to the direction orthogonal to the light incident surface. And it reflects in the V-shaped groove 27 formed in the lower surface of the light-guide plate 2, becomes light with high directivity of a perpendicular direction, and a brightness | luminance becomes high. In addition, the light incident from the light incident surface is reflected on the plane of the groove 3z-2 (where the cross-sectional shape forms a straight line), thereby being reflected on the plane portion of the upper surface or the lower surface of the light guide plate 2. So that it reflects at the same angle. The groove 3z-2 may be configured by combining four parts having a semi-elliptical cross-sectional shape and a bottom having a linear shape. Further, the number of combinations is not limited to four, and may be three or five.

  The present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the technical idea thereof. For example, the light guide plate 2 in FIG. 1 is provided with three point light sources 4-1, 4-2 and 4-3 on one side of the side surface, and two grooves 3-1 and 3-2 are formed. The number is not limited. For example, a light guide plate in which one point light source is provided and one groove is formed may be used.

  1 has grooves 3-1 and 3-2 formed on the upper surface of the light guide plate 2 and a plurality of V-shaped grooves 27 formed on the lower surface, and is similar to the display device 10 of FIG. Further, although the diffusion plate 12 is provided above the light guide plate 2 and the reflection plate 13 is provided below, the light guide plate 2 may be configured upside down. That is, in the lighting device 1, a plurality of V-shaped grooves 27 are formed on the upper surface of the light guide plate 2, grooves 3-1 and 3-2 are formed on the lower surface, and the reflecting plate 13 is provided above the light guide plate 2. A diffusion plate 12 may be provided below.

  Further, the display device 10 of FIG. 5 is configured to include the liquid crystal display panel 11, the diffusion plate 12, the light guide plate 2, and the reflection plate 13 hierarchically from the top to the bottom, but is the same as the lighting device 1. In addition, it may be configured upside down. That is, the display device 10 may be configured to include the reflection plate 13, the light guide plate 2, the diffusion plate 12, and the liquid crystal display panel 11 in a hierarchical manner from top to bottom.

  5 has been described as a liquid crystal display device, the present invention is not limited to a liquid crystal display device, and can be applied to non-self-luminous display devices other than liquid crystals.

It is an external view which shows the structure of the light-guide plate with which the illuminating device by the Example of this invention was equipped. It is a top view of the light-guide plate explaining the direction of the light reflected and reflected in the groove | channel of a light-guide plate. It is sectional drawing of the light-guide plate 2 explaining the reflection of the light with respect to the direction parallel to the light-incidence surface of the groove | channel of a light-guide plate. It is a figure which shows the example of the dimension of the groove | channel of a light-guide plate, and a point light source. It is an external view which shows the structure of the display apparatus using the illuminating device by the Example of this invention. (A)-(d) is an external view which shows the structure of the light-guide plate with which the illuminating device by another Example was equipped. (A)-(e) is a figure which shows the cross-sectional shape of the groove | channel formed in the upper surface of a light-guide plate. It is an external view which shows the structure of the conventional illuminating device. It is a figure which shows sectional drawing of the conventional illuminating device. It is a figure which shows the structure of the light-guide plate used for the conventional illuminating device.

Explanation of symbols

1,20 Illumination device 2, 24, 31 Light guide plate 3, 32 Groove 4 Point light source 10 Display device 11 Liquid crystal display panel 12, 23 Diffuser plate 13, 25 Reflector plate 21 Y direction prism sheet 22 X direction prism sheet 26, 34 lines Light source 27 V-shaped groove 33 Reflective layer

Claims (12)

In an illuminating device including a light source and a light guide plate that reflects light incident from the light source through a light incident surface by a reflection mechanism and emits the reflected light from a light emission surface.
In the light guide plate, a groove having a curved surface for bringing the incident light traveling direction closer to a direction orthogonal to the light incident surface is formed on the light exit surface from the light incident surface toward the surface facing the light incident surface. A lighting device characterized by being formed.   The groove of the light guide plate has at least a part of a semicircular cross-sectional shape on the light incident surface and a cross-sectional shape on the surface facing the light incident surface, and the semicircular diameter increases as the distance from the light incident surface is closer. The lighting device according to claim 1, wherein the lighting device is formed as follows.   The groove of the light guide plate has at least a part of a semicircular cross-sectional shape on the light incident surface and a cross-sectional shape on the surface facing the light incident surface, and the diameter of the semicircular becomes smaller as it is closer to the light incident surface. The lighting device according to claim 1, wherein the lighting device is formed as follows.   The illumination device according to claim 1, wherein the groove of the light guide plate is formed from a light incident surface to a midway to a surface facing the light incident surface.   In the light guide plate, a plurality of grooves having a curved surface are formed in parallel from the light incident surface toward a surface opposite to the light incident surface so that the traveling direction of incident light approaches the direction orthogonal to the light incident surface. The lighting device according to claim 1, wherein   The lighting device according to claim 1, wherein the groove of the light guide plate has a cross-sectional shape parallel to the light incident surface and at least a part of a semicircular shape.   The illumination device according to claim 1, wherein the groove of the light guide plate is formed to have at least a part of an elliptical cross-sectional shape parallel to the light incident surface.   The lighting device according to claim 6 or 7, wherein the groove of the light guide plate is formed so that a cross-sectional shape parallel to the light incident surface has a linear shape.   The lighting device according to claim 1, further comprising one light source and the light guide plate in which the one groove is formed.   9. The light source plate according to claim 1, further comprising: a plurality of the light sources; and the light guide plate in which the groove is formed on a light incident surface between two light sources of the plurality of light sources. The lighting device according to one item.   The minimum distance between the groove and the surface facing the light exit surface of the light guide plate is 0.2 to 0.8 times the distance between the light exit surface of the light guide plate and the surface facing the light exit surface. The illumination device according to any one of claims 1 to 10, wherein   A display device comprising: the illumination device according to any one of claims 1 to 11; and a display panel irradiated with light emitted from the illumination device.

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