JP2002093229A - Back-light unit and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a back-light unit and a liquid crystal display device capable of improving luminance in comparatively simple constitution. SOLUTION: In a light guide plate 2, the plane of light incidence 21 and the light outgoing plane 22 are formed on the side end face. Plural projecting parts 23 are formed on the light outgoing plane. A light source 3 is provided along the plane of light incidence 21. A porous plate 4 is provided with hole parts 41 recessed in the projecting parts 23 of the light guide plate of the number corresponding to the number of the projecting parts. Aluminum foil 42 which is a high reflecting member is deposited on the inner surface of the hole part 41. A lens plate 5 is provided with plural convex lens parts 51. In the present embodiment, the light guide plate 2 is provided with plural projecting parts 23, and the porous plate 4 having plural hole parts recessed in the projecting parts 23 of the light guide plate 2 is provided to thereby emit light entering from the light source 3 much in the light outgoing direction Z of the back-light unit, so that the luminance of a liquid crystal display means can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit and a liquid crystal display.

2. Description of the Related Art In a display device using a backlight unit, a sidelight type backlight unit is often used. The sidelight method is to irradiate a display unit by making light incident from an end face of a light guide means such as a light guide plate, propagating incident light to one surface substantially orthogonal to the end surface, and emitting light from this one surface. is there.

2. Description of the Related Art Backlight units of the sidelight type are becoming mainstream because the entire device can be made thinner as compared with an internally illuminated type in which a light source is disposed inside a display unit. The display device used tends to be required to have a uniform luminance as well as to make the entire device thinner.

[0003] For example, Japanese Patent Laid-Open No.
Japanese Unexamined Patent Publication No. 21720 (hereinafter referred to as prior art) is known. In this conventional technique, in a sidelight type backlight unit, a light guide plate and a reflection plate are joined by an adhesive layer containing particles of light scattering substances, and the area of the adhesive layer containing particles of light scattering substances is reduced. It is arranged in a dot-like manner so as to increase as the distance from the linear light source increases. By controlling the area of the adhesive layer containing the particles of the light-scattering substance or the amount of the light-scattering substance, the uniformity of the luminance can be improved.

However, in the prior art, the light incident on the light guide plate from the light source is diffusely reflected by the adhesive layer containing the light scattering substance and is emitted from the light guide plate. There is a limit to improving the brightness of the backlight unit because the amount of light emitted directly above the surface has an eye field and some light is absorbed by the adhesive layer. Further, in order to improve the luminance, a large light source having a large light output has to be provided, which causes a problem that the backlight unit is increased in size.

[0004] The present invention has been made in view of the above problems, and has as its object to provide a backlight unit and a liquid crystal display device capable of improving luminance with a relatively simple configuration.

According to a first aspect of the present invention, there is provided a backlight unit having a light emitting surface and a light incident surface provided at an end surface substantially perpendicular to the light emitting surface, and further comprising a light emitting surface. A light guide means provided with a plurality of projections on the light guide means; a light source provided on the light incident surface of the light guide means; A perforated plate having a plurality of holes as provided.

In the present invention, definitions and technical meanings of terms are as follows unless otherwise specified.

The light guiding means has a function as a planar light source for optically propagating the light incident from the light incident surface inside and emitting the light from the light exit surface. There is no particular limitation. For example, a light guide system such as a hollow system in which the light guide unit is formed by the reflection unit and the transmission unit is also allowed.

As a preferred light guide means, a light guide plate made of a synthetic resin is used. Further, the shape of the light guide plate is desirably a flat plate, but may be any shape as long as it does not depart from the gist of the present invention.

The light source is preferably a discharge lamp having electrodes at both ends. However, the type of the light source is not particularly limited as long as it emits light at a desired output by being supplied with power from both ends. It may be.

It is preferable that the perforated plate is formed so that the inner surface of the hole has a reflection characteristic.

In the backlight unit of the first aspect, first, light is incident on the light guide means by the light source provided on the light incident surface of the light guide means and propagates inside the light guide means. Then, when the light that has propagated inside the light guide means reaches the convex portion provided on the light guide means, the light is emitted because the critical reflection angle decreases.

The light emitted from the projection of the light guide means enters a perforated plate provided with a hole recessed in the projection of the light guide means. The light incident on the hole of the perforated plate is reflected on the inner surface of the hole in the light emission direction of the backlight unit.

The "light emitting direction of the backlight unit" is a direction of light that is incident on the display unit such as a liquid crystal display device provided immediately above the backlight unit substantially perpendicularly from the backlight unit.

According to the first aspect of the present invention, the light guide means is provided with a plurality of protrusions, and the light guide means is provided with a perforated plate having a plurality of holes recessed in the protrusions of the light guide means. In addition, since a large amount of light incident from the light source can be emitted in the light emission direction of the backlight unit, the brightness of the backlight unit can be improved.

According to a second aspect of the present invention, there is provided a backlight unit having a light emitting surface and a light incident surface provided on an end surface substantially perpendicular to the light emitting surface, and a plurality of concave portions provided on the light emitting surface side. A light source provided on the light incident surface of the light guide; a plurality of holes provided on the light exit surface side of the light guide and protruding from a concave portion of the light guide. And a perforated plate having:

In the backlight unit of the present invention, first, light is incident on the light guide means by the light source provided on the light incident surface of the light guide means and propagates inside the light guide means. Then, when the light propagating inside the light guide means reaches the concave portion provided in the light guide means, the reflection critical angle becomes smaller, so that the light is emitted.

The light emitted from the concave portion of the light guide means enters a perforated plate provided with a hole protruding from the concave portion of the light guide means. The light incident on the hole of the perforated plate is reflected on the inner surface of the hole in the light emission direction of the backlight unit.

According to a second aspect of the present invention, the light source is provided with a plurality of recesses in the light guide means and a perforated plate having a plurality of holes projecting from the recesses of the light guide means. Can be emitted in the light emission direction of the backlight unit, and the brightness of the backlight unit can be improved.

According to a third aspect of the present invention, in the backlight unit according to the first or second aspect, a lens plate is provided on the light emission direction side of the perforated plate.

The lens plate is not particularly limited as long as it is formed of a translucent material. A preferred lens plate is a lens plate provided with a plurality of convex lenses. In this case, the convex lens is preferably formed so that the center of the convex is provided directly above the hole of the perforated plate, but is formed such that the center of the convex is provided between the two holes. May be.

In short, the lens plate only needs to be formed so as to have a light condensing function such that light emitted from the perforated plate is emitted in parallel with the light emission direction of the backlight unit.

According to the third aspect of the present invention, since the lens plate is provided on the light emitting direction side of the perforated plate, the amount of light emitted in the light emitting direction of the backlight unit can be increased. Can be further improved.

According to a fourth aspect of the present invention, in the backlight unit according to any one of the first to third aspects, the hole of the perforated plate is larger on the light emission direction side of the perforated plate than on the light guide means side. Is formed.

According to a fourth aspect of the present invention, in the backlight unit, the hole of the perforated plate is formed such that the light exit direction side of the perforated plate is larger than the light guide means side. Since the light emitted and applied to the inner surface of the hole is more likely to be reflected so as to be parallel to the light emission direction of the backlight unit, the brightness of the backlight unit can be further improved.

According to a fifth aspect of the present invention, in the backlight unit according to any one of the first to fourth aspects, a high reflection member is provided on an inner surface of the hole of the perforated plate.

The material or configuration of the high reflection member is not particularly limited as long as the irradiated light has a desired reflection characteristic.

It is preferable that the high reflection member is formed so as to have a total reflection characteristic by forming the inner surface of the hole by aluminum evaporation or chrome plating.

In the backlight unit of the present invention, the high reflection member is provided on the inner surface of the hole of the perforated plate, so that the light emitted from the convex portion of the light guide means and applied to the inner surface of the hole is Since the light is more easily emitted so as to be parallel to the light emission direction of the backlight unit, the brightness of the backlight unit can be further improved.

According to a sixth aspect of the present invention, there is provided a liquid crystal display device comprising: a backlight unit according to any one of the first and seventh aspects; a device body provided with the backlight unit; and a liquid crystal display means provided in a light emitting direction of the backlight unit. And a liquid crystal display device comprising:

The device main body is not limited in shape, structure and material as long as it is formed so as to be provided with a backlight unit.

It is sufficient that the liquid crystal display device is provided with a backlight unit, a device main body, and a liquid crystal display means. Since the liquid crystal display device has a function as a liquid crystal display device, it is not necessary to provide a desired member other than the above. Needless to say.

According to a sixth aspect of the present invention, there is provided a liquid crystal display device having the function of any one of the first to fifth aspects.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional side view of a liquid crystal display device according to a first embodiment of the present invention, FIG. 2 is a sectional side view showing a light guide plate, a perforated plate and a lens plate, and FIG. FIG. 4 is an explanatory diagram illustrating a light guide plate, FIG. 4 is an explanatory diagram illustrating a perforated plate, and FIG. 5 is an explanatory diagram illustrating a lens plate.

In each of the figures, 1 is an apparatus main body, 2 is a light guide plate as light guide means, 3 is a light source, 4 is a perforated plate, 5 is a lens plate, and 6 is a liquid crystal display means.

The main body 1 is made of a synthetic resin having a high reflectivity, has an opening (not shown) in a rectangular shape, and its inner surfaces 1a, 1b and 1c are formed as reflectors having light reflection characteristics. I have. A lighting device (not shown) is housed inside the apparatus main body 1.

The light source 3 is a cold cathode fluorescent lamp provided along the light incident surface 21 and supported by a lamp holder (not shown).

The light source 3 has an electrode (not shown) at each end, and a wiring (not shown) for electrically connecting the end to the lighting device.

The light guide plate 2 will be described with reference to FIGS.

FIG. 3A is a top view showing a main part of the light guide plate 2, and FIG. 3B is a side view showing a main part of the light guide plate 2.

As shown in FIG. 1, the light guide plate 2 has a flat main body made of a transparent acrylic resin, and has a light incident surface 21 on a side end surface and a light exit surface on one surface substantially orthogonal to the light incident surface 21. Surface 22 is formed. Further, as shown in FIGS. 3A and 3B, a plurality of convex portions 23 are formed on the light emitting surface 22 of the light guide plate 2. The projections 23 are formed with a predetermined interval 1 as shown in FIG. The interval l is 2 mm, A is 0.15 mm, R
Is 0.12 mm.

The perforated plate 4 and the lens plate 5 will be described with reference to FIGS. 2, 4 and 5.

FIG. 2 is an enlarged sectional view of a main part showing a state where the light guide plate 2, the perforated plate 4 and the lens plate 5 are provided.

FIG. 4A is a top view showing a main part of the perforated plate 4, and FIG. 4B is a sectional side view showing a main part of the perforated plate 4. As shown in FIG.

FIG. 5A is a top view showing a main part of the lens plate 5, and FIG. 5B is a side view showing a main part of the lens plate 5.

The perforated plate 4 is made of a translucent plastic material, and a hole 41 formed in the projection 23 of the light guide plate 2 corresponds to the projection as shown in FIGS. It is formed as many as you want.

The holes 41 are formed with a predetermined interval X as shown in FIG. Note that the X interval is 2 mm.

As shown in FIG. 4B, the hole 41 is formed so that the light emitting direction side of the perforated plate 4 is larger than the light guide plate 2 side. An aluminum foil 42 as a reflection member is deposited. Further, as shown in FIG. 4A, the hole 41 has a bottom 43 on the light guide plate 2 side formed in a substantially square shape, and an upper portion 44 on the light emission direction side has a bottom 43. It is formed in a substantially square shape so as to be substantially at the center. B is 1.86m
m and C are 0.9 mm, D is 0.14 mm, and θ is 39 degrees.

The lens plate 5 is provided with a plurality of convex lens portions 51 formed in a convex shape. This convex lens portion 5
1 is formed such that a convex center 52 is provided immediately above the hole 41 of the perforated plate 4 as shown in FIG.

The convex lens portions 51 are formed with a predetermined interval Y as shown in FIG. Note that Y
The interval is 2 mm, and E in FIG. 5B is 0.88 m.
m and F are 0.5 mm.

The arrow P in FIG.
This is an example of light that enters from the lens and exits from the lens plate 5.

The operation of the first embodiment will be described.

First, light is incident on the light guide plate 2 by the light source 3 provided on the light incident surface 21 of the light guide plate 2 and propagates inside the light guide plate 2. When the light propagating inside the light guide plate 2 reaches the convex portion 23 provided on the light guide plate 2, the critical reflection angle decreases, and as shown in FIG. Is emitted.

The light emitted from the projection 23 of the light guide plate 2 is
The hole 41 of the perforated plate 4 which is recessed in the protrusion 23
Irradiated on the inner surface. The light applied to the inner surface of the hole 41 is formed such that the hole 41 is formed to be larger on the light emission direction side of the perforated plate 4 than on the light guide plate 2 side, and the aluminum foil 42 is deposited on the inner surface of the hole 41. As a result, the light is totally reflected in the light emission direction Z of the backlight unit in FIG.

The light emitted from the perforated plate 4 enters the lens plate 5 having the convex lens portion 51 and is refracted so as to be more parallel to the light emitting direction Z, and is emitted from the lens plate 5. Is irradiated.

In the first embodiment, the light guide plate 2 has a plurality of convex portions 2.
3 is provided, and the porous plate 4 having a plurality of holes 41 recessed in the convex portion 23 of the light guide plate 2 is provided, so that light incident from the light source 3 can be emitted from the backlight unit. Since a large amount of light can be emitted in the emission direction Z, the brightness of the liquid crystal display means 6 can be improved.

Further, the hole 41 is formed so that the light emission direction side is larger than the light guide plate 2 side, and the hole 4
By vapor-depositing aluminum, which is a highly reflective member, on the inner surface of the backlight unit 1, the light is totally reflected in the light emission direction Z of the backlight unit, so that the brightness of the liquid crystal display unit 6 can be further improved.

Further, since the perforated plate 4 can be provided by recessing the light guide plate 2, it is possible to easily obtain a configuration capable of improving the luminance.

Next, a second embodiment will be described with reference to FIG.

FIG. 6A is a top view showing a main part of a perforated plate 40 according to a second embodiment, and FIG. 6B is a side sectional view showing a main part of the perforated plate 40 similarly. The same components as those of the embodiment are denoted by the same reference numerals, and description thereof will be omitted.

The hole 71 of the perforated plate 7 is formed such that the light emitting direction side of the perforated plate 7 is larger than the light guide plate 2 side, as shown in FIG.
As shown in FIG. 4A, the bottom 72 on the light guide plate 2 side is used.
Are formed in a substantially circular shape, and the upper portion 73 on the light emission direction side is formed in a substantially circular shape such that the bottom portion 72 is substantially at the center.

The second embodiment has the same effects as the first embodiment.

In the first and second embodiments, the convex portion 23, the holes 41 and 71, and the convex lens portion 51 of the lens plate are formed at predetermined intervals. It can be provided at different intervals so as to have.

Further, a concave portion may be provided instead of the convex portion 23 of the light guide plate 2, and the holes 41, 71 of the perforated plates 4, 7 may be formed so as to protrude into the concave portion. In this case, the same effects as those of the first embodiment and the second embodiment are obtained.

[0063]

According to the first aspect of the present invention, the light guide means is provided with a plurality of projections, and the porous plate is provided with a plurality of holes which are recessed in the protrusions of the light guide means. Accordingly, a large amount of light incident from the light source can be emitted in the light emission direction of the backlight unit, so that the brightness of the backlight unit can be improved.

According to a second aspect of the present invention, the light source is provided with a plurality of recesses and a perforated plate having a plurality of holes projecting from the recesses of the light guide means. Can be emitted in the light emission direction of the backlight unit, and the brightness of the backlight unit can be improved.

According to the third aspect of the present invention, since the lens plate is provided on the light emission direction side of the perforated plate, the amount of light emitted in the light emission direction of the backlight unit can be increased. Can be further improved.

According to a fourth aspect of the present invention, in the backlight unit, the hole of the perforated plate is formed so that the light exit direction side of the perforated plate is larger than the light guide means side. The light emitted and applied to the inner surface of the hole is more likely to be reflected so as to be parallel to the light emission direction of the backlight unit, so that the brightness of the backlight unit can be further improved.

According to the backlight unit of the present invention, since the high reflection member is provided on the inner surface of the hole of the perforated plate, the light emitted from the convex portion of the light guide means and irradiated on the inner surface of the hole is Since the light is more easily emitted so as to be parallel to the light emission direction of the backlight unit, the brightness of the backlight unit can be further improved.

The liquid crystal display device according to the sixth aspect has the effect according to any one of the first to fifth aspects.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional side view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional side view showing a light guide plate, a perforated plate, and a lens plate.

FIG. 3 is an explanatory diagram illustrating a light guide plate as a light guide unit.

FIG. 4 is an explanatory view showing a perforated plate;

FIG. 5 is an explanatory view showing a lens plate according to the first embodiment;

FIG. 6 is an explanatory view showing a perforated plate of the liquid crystal display device according to the second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Device main body, 2 ... Light guide plate which is a light guide means, 3 ... Light source, 4 ... Perforated plate, 5 ... Lens plate, 6 ... Liquid crystal display means,

Claims (6)

[Claims] 1. A light guide means having a light emitting surface and a light incident surface provided on an end surface substantially orthogonal to the light emitting surface, and a plurality of convex portions provided on the light emitting surface side; A light source provided on the light incident surface of the light guide means; a perforated plate provided on the light emission surface side of the light guide means, and having a plurality of holes recessed in the projections of the light guide means; A backlight unit comprising: 2. Light guide means having a light exit surface and a light entrance surface provided on an end surface substantially orthogonal to the light exit surface, and having a plurality of recesses provided on the light exit surface side; A light source provided on the light incident surface of the light means; and a perforated plate provided on the light emitting surface side of the light guide means and having a plurality of holes protruding from the concave portion of the light guide means. A backlight unit, comprising: 3. The backlight unit according to claim 1, wherein a lens plate is provided on the light emission direction side of the perforated plate. 4. The backlight according to claim 1, wherein the holes of the perforated plate are formed such that the light emitting direction side of the perforated plate is larger than the light guide means side. unit. 5. The backlight unit according to claim 1, wherein a high reflection member is provided on an inner surface of the hole of the perforated plate. 6. A backlight unit according to claim 1, further comprising: a device body provided with the backlight unit; and a liquid crystal display provided in a light emitting direction of the backlight unit. Characteristic liquid crystal display device.