JP2013134888A - Lighting device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device of high luminance with optical deflection elements concealed, and a display device using the same.SOLUTION: First lenses 19 extended in a first direction arranged on an emission surface 7b of a light guide 7 and second lenses 22 extended in a second direction perpendicular to the first lenses 19 are laminated. With this arrangement, light emitted from a light source 6 is deflected by optical deflection elements 18 at the light guide 7 and is converted into linear light L by the first lenses 19. Further, the linear light L is converted into planar light by the second lenses 22 of a diffusion lens sheet 20 arranged on an emission surface 7b side of the light guide 7. With this arrangement, a lighting device 3 and a display device 1 can conceal the optical deflection elements 18 even without laminating a diffusion sheet of scattering properties on the emission surface 7b side of the light guide 7, so that converging effects by the first lenses 19 formed on the emission surface 7b of the light guide 7 are not obstructed, thereby obtaining the lighting device 3 of high luminance.

Description

  The present invention relates to an illumination device and a display device used for a display panel such as a liquid crystal display device.

  In recent large-sized liquid crystal televisions, flat display panels and the like, direct type illumination devices or edge light illumination devices are mainly employed.

  In the direct type illumination device, a plurality of cold cathode tubes and LEDs (Light Emitting Diodes) are used as light sources, and regularly arranged on the back surface of an image display element panel such as a liquid crystal panel. Since the cold cathode tube is a linear light source and the LED is a point light source, a diffuser plate having a strong light scattering property is used between the image display element panel and the light source, and the cold cathode tube and the LED are not visually recognized. I am doing so.

  In the edge light type lighting device, a plurality of cold cathode fluorescent lamps and LEDs are arranged on an end face of a light-transmitting plate called a light guide plate. Generally, the surface facing the exit surface of the light guide plate (the surface facing the image display element panel) is a light deflection surface, and the light deflection element that efficiently guides incident light incident from the end surface of the light guide plate to the exit surface. Is formed. A light deflection element formed on such a light deflection surface is generally one in which white ink is printed in a dot shape (see, for example, Patent Document 1).

By the way, recently, for the purpose of improving the moving image performance of the liquid crystal display device, reducing the crosstalk of the active 3D image, or increasing the brightness of the illumination device, a light guide plate having a lenticular lens and a prism lens arranged on the exit surface side is provided. A configuration is proposed.
In such a configuration, compared to the case where the exit surface is flat, the exit light can be condensed in the front direction of the exit surface by a lenticular lens or a prism lens, so that a high-intensity light guide plate can be obtained. .

JP-A-1-241590

However, the edge light type illumination device needs to be laminated with a strong diffusion sheet having high scattering performance so that the light deflection element formed on the light deflection surface of the light guide plate is not visually recognized. Particularly in recent edge light type lighting devices, the number of LEDs arranged from the viewpoint of cost reduction has decreased, and the thickness of the light guide plate has also decreased. For this reason, the light deflection element is more easily visible, and the importance of the strong diffusion sheet is increasing.
In such an edge light type illumination device, even if a lenticular lens or a prism lens is arranged on the exit surface of the light guide plate, the exit light condensed in the front direction of the exit surface by the lenticular lens or the prism lens is on it. It will be scattered by the laminated strong diffusion sheet. For this reason, there arises a problem that the condensing effect by the lenticular lens or the prism lens is greatly reduced and the luminance is also lowered.
Accordingly, an object of the present invention is to provide a high-luminance illumination device and a display device using the illumination device while concealing a light deflection element.

The present invention employs the following means in order to solve the above problems.
That is, the illumination device according to the first aspect of the present invention includes a light source, a light guide that guides light incident from the light source in a predetermined direction, and light diffusion that diffuses light emitted from the light guide. A light guide, an incident surface on which light from the light source is incident, an exit surface that is orthogonal to the incident surface and emits light incident from the incident surface, and an optical deflection that faces the exit surface And a plurality of point-like light deflecting elements provided on the light deflecting surface and deflecting light incident from the incident surface toward the exit surface, and the light diffusing portion is a first parallel to the exit surface. A first lens that is continuous in the direction and restricts the optical path of the light guided inside the light guide and emits it as linear light, and is continuous in a second direction that is parallel to the emission surface and orthogonal to the first direction And a second lens that diffuses the linear light emitted from the first lens into a planar shape.
According to such a configuration, the light from the light source enters the light guide from the incident surface. The incident light is deflected toward the exit surface by the light deflecting element of the light deflecting surface of the light guide, and this light includes a part of the point light deflected by the light deflecting element. The light is converted into linear light by one lens, and is further diffused by the second lens to become planar light having a uniform distribution.

  In the lighting device of the present invention, a diffusion sheet that diffuses the light emitted from the second lens may be further formed.

In the illuminating device of the present invention, the light deflection element occupies a larger area on the light deflection surface in the direction orthogonal to the incident surface, on the side farther from the incident surface than the side closer to the incident surface. In the direction parallel to the incident surface, the area occupied by the light deflection element per unit area may be substantially uniform.
The amount of light that guides the inside of the light guide increases as it gets closer to the incident surface, and decreases as it moves away. Therefore, by forming more light deflection elements closer to the incident surface, it is possible to equalize the amount of light emitted from the emission surface.

  In the illuminating device of the present invention, the light deflection element may be formed in an independent convex shape or a concave dot shape.

  In the illuminating device of the present invention, the first lens has a cylindrical shape whose cross section is an arc shape or a non-arc shape cross section and a convex shape or a concave shape, or a partially rounded prism shape, A plurality may be arranged side by side along the direction.

  In the illuminating device of the present invention, the second lens has a cylindrical shape in which the cross section is an arc shape or a non-arc shape in cross section and a convex shape or a concave shape, or a partially rounded prism shape, A plurality may be arranged side by side in this direction.

In the illumination device of the present invention, the second lens may be formed on a sheet-like base material.
And the diffusion layer which diffuses light may be formed in the surface facing the surface where the 2nd lens is arrange | positioned in a base material.
The base material may be configured by dispersing diffusible particles therein.

  In the illuminating device of this invention, you may further provide the reflecting plate which reflects the light scattered from the light guide or the light source to the light guide side at the light deflection surface side of the light guide.

  A display device according to a second aspect of the present invention includes an image display element that defines a display image in accordance with transmission or shading of light in pixel units, and the illumination device of the present invention. .

According to the present invention, the light from the light source enters the light guide from the incident surface. The incident light is deflected toward the exit surface by the light deflection element of the light deflection surface of the light guide. The light includes a part of point light deflected by the light deflecting element, which is converted into linear light by the first lens, and the linear light is a second light orthogonal to the first lens. It is made planar light by the lens.
That is, it is possible to prevent the light deflection element from being visually recognized without stacking a strong diffusion sheet having high scattering performance. Since light is not scattered by the strong diffusion sheet, a high-luminance lighting device can be obtained. Therefore, it is possible to provide a high-luminance illumination device and a display device using the illumination device while hiding the light deflection element.

It is a cross-sectional schematic diagram of the display apparatus of this embodiment. (A) is a light-guide body perspective view of this embodiment, (b) is a light-guide body side view, (c) is a light-guide body side view of this embodiment. (A) is an example of the shape of a 1st lens and a 2nd lens, (b) is another example of the shape of a 1st lens and a 2nd lens. (A) is the top view which showed the light guide in a light guide, (b) is the side view which showed the light guide. (A) is the top view which showed the light guide in the light guide of this embodiment, (b) is a side view. (A) is the figure which showed the luminance distribution in a light guide, (b) is the figure which showed the luminance distribution in the light guide of this invention. (A) is the top view which showed the emitted light in the light guide of this embodiment, (b) is the side view which showed the emitted light. (A) is an example of the shape of a 1st lens and a 2nd lens, (b) is another example of the shape of a 1st lens and a 2nd lens.

Hereinafter, an embodiment for carrying out an illumination device and a display device according to the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited only to this embodiment.
FIG. 1 is a schematic cross-sectional view of an illuminating device 3 including a light guide 7 and a display device 1 including the illuminating device 3 according to an embodiment of the present invention.

  A display device 1 shown in FIG. 1 includes an image display element 2 and an illumination device 3 arranged facing the light incident side of the image display element 2.

  As an image display element, the liquid crystal display element 2 is mentioned, for example. The liquid crystal display element 2 has a structure including polarizing plates 10 and 11 on both surfaces of the liquid crystal layer 9. The liquid crystal display element 2 is a typical element that displays an image by defining a display image by transmitting or blocking light in pixel units, and has higher image quality than other display elements. And manufacturing cost can be reduced.

  The illumination device 3 includes a weak diffusion sheet (diffusion sheet) 28, a diffusion lens sheet 20, a light guide body 7, a reflection plate 5, and a light source 6 disposed so as to face the light incident side of the image display element 2. Yes.

  Although the reflecting plate 5 is disposed at least on the surface facing the light guide 7, it may be disposed at a position facing the surface where the light source 6 is not disposed among the four side end surfaces of the light guide 7. .

An example of the light source 6 is a point light source. Examples of the point light source include an LED (light emitting diode), and examples of the LED include a white LED and an RGB-LED composed of red, green, and blue chips that are the three primary colors of light.
The light source 6 may be a fluorescent tube represented by CCFL (cold cathode tube).
Such a light source 6 is arranged along one incident surface 7 </ b> L of the plate-shaped light guide 7. Not only this but the light source 6 may be arrange | positioned in two end surfaces which oppose in the light guide 7, or may be arrange | positioned in four end surfaces. Further, the shape of the light guide 7 may be a wedge shape or the like instead of the flat plate shape as shown in FIG.

  The light guide 7 is made of a material having transparency, the side facing the liquid crystal display element 2 is an emission surface 7b, and the light deflection surface 7a is formed on the surface opposite to the emission surface 7b. .

  On the light deflection surface 7 a of the light guide 7, a light deflection element 18 that deflects incident light from the light source 6 toward the emission surface 7 b is formed. As the light deflection element 18, for example, white diffuse reflection dots are printed. Another example of the light deflection element 18 includes a concave or convex structure such as a microlens shape or a prism shape.

FIG. 2A is a perspective view of the light guide 7 of the present invention when the light deflection element 18 is, for example, a concave microlens. 2B is a cross-sectional view as viewed from the incident surface 7L side, and FIG. 2C is a cross-sectional view in a direction orthogonal to the incident surface 7L.
As shown in FIGS. 2A and 2C, the light deflection element 18 is arranged on the side farther from the incident surface 7L than the side closer to the incident surface 7L in the direction orthogonal to the incident surface 7L. As shown in FIGS. 2 (a) and 2 (b), in the direction parallel to the incident surface 7L, the light deflection elements 18 per unit area It is preferable that the occupied area is substantially uniform.
The amount of light that guides the inside of the light guide 7 increases as the distance from the incident surface 7L increases, and decreases as the distance increases. Accordingly, the number of the light deflection elements 18 decreases as the distance from the incident surface 7L increases, and as the distance from the light deflection element 18 increases, the amount of light emitted from the emission surface 7b can be equalized.
Here, the size of the light deflection element 18 may be changed instead of arranging the light deflection element 18 in a sparse / dense manner. In other words, the closer to the incident surface 7L, the smaller the size of the light deflection element 18, and the larger the distance is. This also makes it possible to equalize the amount of light emitted from the exit surface 7b.

  As shown in FIGS. 2A to 2C, a first lens (light diffusion portion) 19 is formed on the exit surface 7 b of the light guide 7 on the exit surface 7 b of the light guide 7. . The function of the first lens 19 will be described in detail below.

The first lens 19 is a lens that extends in the direction (first direction) perpendicular to the incident surface 7L along the exit surface 7b, and a plurality of lenses are regularly arranged on the exit surface 7b. The first lens 19 is a convex curved cylindrical lens having a circular arc shape as shown in FIG. 3A or a non-arc-shaped cylindrical lens as shown in FIG. Is desirable.
The plurality of first lenses 19 may be arranged densely so as to contact each other in the direction along the incident surface 7L on the exit surface 7b, or intermittently arranged at intervals. You can also.

The effect of the first lens 19 will be described with reference to FIGS.
4A is a top view of the light guide 7 without the first lens 19, and FIG. 4B is a side view seen from the incident surface 7L side. FIG. 5A is a top view of the light guide 7 on which the first lens 19 is formed, and FIG. 5B is a side view seen from the incident surface 7L side. Each illustrates the behavior of light when the light source 6 is disposed at the center of one of the long sides of the light guide 7 that is rectangular.

  As shown in FIGS. 4A and 4B, when the first lens 19 is not provided, the light emitted from the light source 6 enters the light guide 7 from the incident surface 7L, and the inside of the light guide 7 is fan-shaped. Light is guided while spreading. On the other hand, when the first lens 19 is present, as shown in FIGS. 5A and 5B, the light incident from the incident surface 7L repeats internal reflection by the first lens 19 and is guided in one direction. Shine. That is, since the light guide is guided in a certain area without spreading in a fan shape, it is useful for controlling the light emission area of the backlight such as scanning backlight or local dimming.

  Another effect of the first lens 19 will be described with reference to FIGS. 6 (a) and 6 (b), as an example, a plurality of light sources 6 are arranged along two long sides of the light guide 7, and the light deflection element 18 is sparser as it is closer to the incident surface 7L. That is, the luminance distribution is shown when the light guide 7 is arranged closer to the center and closer in the direction parallel to the incident surface 7L.

If the light deflection element 18 is arranged closer to the incident surface 7L, or the number of the light deflection elements 18 is smaller, the light deflecting element 18 enters the light guide 7 from the light source 6 and guides the inside of the light guide 7. The light whose path is changed by the deflection element 18 is emitted from the emission surface 7b.
FIG. 6A shows the luminance distribution when the first lens 19 is not provided. The light deflection element 18 is arranged so that the luminance becomes higher toward the center of the light guide 7. However, a triangular dark portion D is generated on the short side where the light source 6 of the light guide 7 is not disposed. As shown in FIGS. 4A and 4B, the dark portion D is caused by the fact that light incident on the light guide 7 from the light source 6 spreads in a fan shape and guides the light. Are caused by superposition of the light guides and light leakage from the short side where the light source 6 is not disposed. Therefore, normally, the light deflection element 18 needs to be formed in a two-dimensional dense pattern so that the dark portion D does not occur and the central luminance of the light guide 7 is increased.

  On the other hand, FIG. 6B shows the luminance distribution when the first lens 19 is formed. Similarly to the above, the light deflection element 18 is arranged so that the luminance increases as it approaches the center of the light guide 7. As shown in FIGS. 5A and 5B, the light incident on the light guide 7 from the light source 6 does not spread in a fan shape and travels straight, so that the dark part D as shown in FIG. 6A does not occur. . That is, it is possible to obtain the lighting device 3 in which the dark portion D does not occur even in the one-dimensional dense / dense pattern without designing a complicated two-dimensional dense / dense pattern. This is particularly advantageous when it is desired to seamlessly form the light guide body 7 of the present invention by roll-to-roll by extrusion molding or the like.

  Moreover, as for the display apparatus 1 using the light guide 7 of this invention, it is desirable that a brightness | luminance is so high that the screen center. Since the light deflection element 18 of the light guide 7 on which the first lens 19 is formed is one-dimensional sparse / dense, the luminance at the center of the screen can be adjusted by appropriately adjusting the sparse / dense pattern in the direction orthogonal to the incident surface 7L. However, the luminance is substantially uniform in the direction parallel to the incident surface 7L. Therefore, by adjusting the input current to the plurality of light sources 6, it is possible to adjust the luminance in the direction parallel to the incident surface 7 </ b> L so that the luminance becomes higher toward the center of the screen.

  Furthermore, another effect of the first lens 19 will be described with reference to FIGS. FIG. 7A is a top view of the light guide 7 of the present invention, and the first lens 19 is not shown for the sake of simplicity. FIG. 7B is a side view of the light guide 7 according to the present invention as viewed from the incident surface 7L side. For the sake of simplicity, the light source 6 is not displayed and only one representative light deflection element 18 is displayed. . The light whose path has been changed by the light deflecting element 18 is emitted while the path is further changed by refraction by the first lens 19 disposed on the exit surface 7b. At this time, when the light guide 7 is observed from the exit surface 7 b side, the point-shaped light deflection element 18 is connected and visually recognized as the linear light L by the refraction effect of the first lens 19. The extending direction of the linear light L is the same as the direction in which the first lenses 19 are arranged.

As described above, as the first lens 19 for deflecting the light deflection element 18 formed in a dot shape to the linear light L, as shown in FIG. It is desirable that the convex curved cylindrical lens has a non-circular cross section as shown in b). This is because the tangent angle of the convexly curved cylindrical lens with respect to the exit surface 7b varies depending on the position, so that it is easy to convert the dotted light deflection element 18 into the linear light L.
On the other hand, a prism lens is generally not preferable as the first lens 19. This is because the prism lens with respect to the exit surface 7b has a constant tangent angle, so that the dotted light deflection element 18 is not converted into the linear light L but split into two dotted lights. When a prism lens is employed, it is desirable that the prism lens has a curved top as shown in FIG. 8A or a prism lens with a curved side as shown in FIG. 8B. .

The diffusing lens sheet 20 is disposed on the exit surface 7b side of the light guide 7 of the present invention. The diffusing lens sheet 20 has an incident surface 20a facing the light guide 7 on one surface side and an exit surface 20b facing the incident surface 20a on the other surface side.
The diffusing lens sheet 20 is provided on the light-transmitting base material 21 and the emission surface 20b side, and a second lens (which converts the light converted into the linear light L by the first lens 19 into planar light ( Light diffusing unit) 22.

The second lens 22 is in a direction (second direction) substantially orthogonal to the first lens 19 formed on the emission surface 7b of the light guide 7 on the surface (exit surface 20b side) of the base material 21. Extend. As the shape of the second lens 22 for converting the linear light L into the planar light, the cross-sectional arc shape shown in FIG. 3A or the non-circular cross-section shape shown in FIG. A convexly curved cylindrical lens is desirable. Alternatively, a prism lens having a curved top portion as shown in FIG. 8A or a prism lens having a curved side surface as shown in FIG. 8B is desirable.
A plurality of such second lenses 22 are provided side by side along the direction in which the first lens 19 extends. The plurality of second lenses 22 may be arranged densely so as to be in contact with each other, or may be arranged intermittently at intervals.

Such a diffusing lens sheet 20 may have isotropic diffusibility. Specifically, a diffusion layer is provided on the incident surface 20 a of the diffusion lens sheet 20 on the side facing the light guide 7. For this purpose, the incident surface 20a may be roughened to form a concavity and convexity for diffusing light, or a diffuser may be applied to the incident surface 20a, for example, to diffuse light. You may apply coating by. Further, the base material 21 of the diffusing lens sheet 20 may have a configuration in which diffusible particles that diffuse light are dispersed therein.
Thereby, moire interference fringes generated between the light deflection element 18 formed on the light guide 7, the first lens 19, and the second lens 22 formed on the diffusion lens sheet 20 can be suppressed. .

In the present embodiment, the weak diffusion sheet 28 is disposed on the exit surface 20 b side of the diffusion lens sheet 20.
The weak diffusion sheet 28 may have a configuration in which a coating with a substance that diffuses light or unevenness that diffuses light is formed on the surface thereof. Further, the weak diffusion sheet 28 may have a configuration in which diffusible particles that diffuse light are dispersed therein.
This weak diffusion sheet 28 suppresses moire interference fringes generated between the light deflection element 18 formed on the light guide 7, the first lens 19, and the second lens 22 formed on the diffusion lens sheet 20. Furthermore, moire interference fringes generated between the second lens 22 and the liquid crystal display element 2 can also be suppressed.

  As described above, the light emitted from the light source 6 is deflected by the light deflection element 18 in the light guide 7 and converted into the linear light L by the first lens 19. Further, the linear light L is converted into planar light by the second lens 22 of the diffusing lens sheet 20 disposed on the light exit surface 7 b side of the light guide 7. Thereby, since the light deflection element 18 visually recognized in the form of dots is converted into planar light, it is not visually recognized by the observer.

  The illumination device 3 and the display device 1 can conceal the light deflection element 18 without stacking a highly scattering diffusion sheet on the light exit surface 7 b side of the light guide 7. Since the light condensing effect by the first lens 19 formed on the surface 7b is not hindered, the high-luminance illumination device 3 can be obtained.

(Other embodiments)
The present invention is not limited to the above-described embodiment described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, the illumination device 3 of the present invention is not applied only to the display device 1. That is, as a matter of course, the illumination device 3 having a function of efficiently collecting the light emitted from the light source 6 can be used for, for example, an illumination device.
Further, the weak diffusion sheet 28 is not an essential configuration, and the weak diffusion sheet 28 may be omitted as long as sufficiently uniform illumination light is obtained by the first lens 19 and the second lens 22.
In addition, the first lens 19 is formed integrally with the light guide 7 and the second lens 22 is provided on the base material 21. However, like the second lens 22, the first lens 19 is attached to the sheet. The light guide 7 can be formed separately from the light guide 7. Further, the first lens 19 may be formed integrally with the base material 21.

  In addition to this, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Display apparatus, 2 ... Liquid crystal display element (image display element), 3 ... Illuminating device, 5 ... Reflecting plate, 6 ... Light source, 7 ... Light guide, 7L ... Incident surface, 7a ... Light deflection surface, 7b ... Ejection Surface 18, light deflecting element 19, first lens (light diffusing part), 20 diffusing lens sheet, 20 a, incident surface, 20 b, exit surface, 21 substrate, 22, second lens (light diffusion) Part), 28 ... Weak diffusion sheet (diffusion sheet)

Claims (11)

A light source;
A light guide that guides light incident from the light source in a predetermined direction;
A light diffusing portion for diffusing the light emitted from the light guide;
With
The light guide is
An incident surface on which light from the light source is incident;
An exit surface that is orthogonal to the incident surface and emits the light incident from the incident surface;
A light deflection surface facing the exit surface;
A plurality of point-like light deflecting elements provided on the light deflecting surface and deflecting the light incident from the incident surface toward the exit surface;
The light diffusion part is
A first lens that is continuous in a first direction parallel to the emission surface, and that emits the light as linear light by regulating an optical path of the light that guides the inside of the light guide;
A second lens that is parallel to the emission surface and is continuous in a second direction orthogonal to the first direction, and diffuses the linear light emitted from the first lens into a planar shape. A lighting device.   The illumination device according to claim 1, further comprising a diffusion sheet that diffuses light emitted from the second lens.   In the direction perpendicular to the incident surface on the light deflection surface, the light deflection element has a larger area occupied by the light deflection element on the side farther from the incident surface than the side closer to the incident surface. The formed area of the light deflection element per unit area is substantially uniform in a direction parallel to the incident surface on the light deflection surface. Lighting equipment.   The illumination device according to any one of claims 1 to 3, wherein each of the light deflection elements has an independent convex or concave dot shape.   The first lens has a cylindrical shape whose cross section is an arc shape or a non-arc shape cross section and a convex shape or a concave shape, or a partially rounded prism shape, and a plurality of the first lenses are arranged along the second direction. Is arranged, The illuminating device as described in any one of Claim 1 to 4 characterized by the above-mentioned.   The second lens has a cylindrical shape whose cross section is an arc shape or a non-arc shape cross section and a convex shape or a concave shape, or a partially rounded prism shape, and a plurality of the second lenses are arranged along the first direction. Is arranged, The illuminating device as described in any one of Claim 1 to 5 characterized by the above-mentioned.   The lighting device according to any one of claims 1 to 6, wherein the second lens is formed on a sheet-like base material.   The illumination device according to claim 7, wherein a diffusion layer that diffuses light is formed on a surface of the base material that faces a surface on which the second lens is disposed.   The lighting device according to claim 7, wherein the base material has diffusible particles dispersed therein.   10. The reflector according to claim 1, further comprising a reflector that reflects light scattered from the light guide or the light source to the light guide side on the light deflection surface side of the light guide. 10. The lighting device according to item. An image display element that defines a display image according to light transmission or shading in pixel units;
The lighting device according to any one of claims 1 to 10,
A display device comprising: