JP3175103B2 - Liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device having a liquid crystal display panel and a surface light source used for illuminating the liquid crystal display panel.

[0002]

2. Description of the Related Art A generally known liquid crystal display device is provided with a surface light source unit which emits light with uniform brightness from a planar light emitting surface so that the entire surface of the liquid crystal display panel is uniformly illuminated. I have.

In order to increase the brightness of the illumination from the surface light source, a transparent plate as shown in FIG. 6 is used on the light emitting surface of the surface light source. The transparent plate has a refraction surface having a large number of triangular cross-sections, like the cross-sectional shape of a Fresnel lens, and a plurality of linear projections whose ridges (vertexes) are arranged in parallel as shown in FIG. Is a transparent plate.

When the transparent plate 4 is disposed between the surface light source unit 1 and the liquid crystal display panel 3 as shown in FIG. 5, light from the surface light source unit 1 illuminates the liquid crystal display plate 3 through the transparent plate 4. It is known that the brightness increases by about 20 to 30% and the display screen of the liquid crystal display panel 3 becomes bright.

[0005]

However, when a transparent plate 4 having a cross section similar to that of a Fresnel lens is arranged on the light emitting surface of the surface light source section 1 and the liquid crystal display panel 3 is illuminated, Although the brightness increases, there are drawbacks such as a stripe pattern such as moiré stripes appearing on the surface of the liquid crystal display panel 3 and the image on the liquid crystal display panel 3 is difficult to see.

[0006]

A liquid crystal display device according to the present invention comprises: a surface light source section for emitting light of substantially constant brightness over the entire surface in a planar shape; and a front surface of the surface light source section having a substantially triangular cross section. A liquid crystal display comprising: a transparent plate having a large number of linear projections formed in a shape such that the ridge lines thereof are substantially parallel to each other; and a liquid crystal display plate to which light from the surface light source unit is irradiated through the transparent plate. The device is characterized in that the ridge line of the linear projection of the transparent plate is oblique to the side of the liquid crystal display panel.

The surface light source section has a light guide, and a primary light source disposed opposite to an incident end face of the light guide, and transmits the light from the primary light source incident from the incident end face to the light source. A light-guiding surface light source unit that emits light from the surface of the light guide while propagating through the light guide and serves as illumination light can be provided.

In the liquid crystal display device of the present invention, light from a primary light source is made incident from an incident end face so that light incident from the incident end face is emitted from the light guide surface while propagating through the light guide. At the same time, the light emitted from the surface of the light guide is irradiated to the liquid crystal display panel through a transparent plate having a large number of linear projections formed so that the cross-sectional shape is substantially triangular and the ridge lines are substantially parallel. In the liquid crystal display device described above, the ridge line of the linear convex portion of the transparent plate may be inclined with respect to the incident end face of the light guide.

[0009]

Next, an embodiment of the liquid crystal display device of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the outline of the configuration of an embodiment of the present invention, wherein 1 is a surface light source unit, 2 is a light emitting surface, and 3 is a liquid crystal display panel. The liquid crystal display panel 3 is placed on the light emitting surface 2 side of the surface light source unit 1, and an image is observed on the liquid crystal display panel 3 by illumination by the surface light source unit 1. Reference numeral 10 denotes a transparent plate having a large number of linear projections 11 having a triangular cross section (see FIG. 1), and ridge lines (vertexes) 12 of the respective linear projections 11 being parallel. They are formed side by side (see FIG. 2). Transparent plate 10 having such a shape
By effectively utilizing the light from the surface light source unit 1,
It is used to increase the brightness of illumination by the surface light source unit 1. In other words, the transparent plate 10 allows the light from the surface light source unit 1 to be effectively used as illumination light by the refraction of the linear projections 11 so that the liquid crystal display panel 3 can be brightly illuminated. I have. Here, when the liquid crystal display device is configured such that the light from the surface light source unit 1 is irradiated on the liquid crystal display panel 3 through the transparent plate 10 as shown in FIG. The ridge line of the part 11 is the side 3 of the liquid crystal display panel 3.
a with respect to a.

In this embodiment, since the transparent plate 10 having the Fresnel lens-shaped refracting surface is arranged, the brightness of the illumination by the surface light source unit 1 of the liquid crystal display panel 3 is increased, and the observation of a bright display image is performed. Becomes possible. Moreover, the transparent plate 10
, A good image can be observed without generating a fringe pattern such as a moiré fringe.

The surface light source unit 1 in the above embodiment includes:
For example, a structure as shown in FIG. 3 can be used. That is, FIG. 3 shows an example of a so-called light guide type surface light source unit 1, and a linear light source 15 such as a cold cathode tube is opposed to one side surface of a light guide 16 made of a transparent body. The light source 15 is arranged as a primary light source, and light emitted from the light source 15 enters the light guide 16. On the lower surface side of the light guide 16, a reflection surface 18 is disposed.
A diffusing plate 17 is arranged on the upper surface side of 6. On the other hand, a transparent plate 10 is disposed on the upper surface side of the surface light source unit 1 in FIG. 3 as shown in FIGS. As described with reference to FIGS. 1 and 2, the transparent plate 10 has a large number of linear protrusions 11 formed upward. A large number of the linear convex portions 11 are formed so that the cross-sectional shape thereof is substantially triangular and their ridge lines (vertexes) 12 are arranged in parallel.
6 are formed so as to be oblique to the incident surface 16a (see FIGS. 1 to 3). As a result, the projections 11 of the transparent plate 10 shown in FIGS. 1 and 2 are also inclined with respect to the side 3 a of the rectangular liquid crystal display panel 3. The light guide type surface light source device configured as described above allows the light from the light source 15 to be incident from the incident end face 16a and propagates the light incident from the incident end face 16a in the light guide 16 while the light guide The light emitted from the upper surface of the light guide 16 is applied to the liquid crystal display panel 3 through the diffusion plate 17 and the transparent plate 10.

Further, as another example of the surface light source section 1, a linear light source 20, a reflection plate 21, and a diffusion plate 22 as shown in FIG. Later light may pass through the diffusion plate 22 to become diffused light, and the diffused light may be used as illumination light, such as a so-called direct light source device.

[0014]

The liquid crystal display device of the present invention uses a transparent plate having a large number of linear projections formed so that the cross-sectional shape is substantially triangular and the ridges are substantially parallel. The display panel can be illuminated more brightly, and the stripes on the surface of the liquid crystal display panel can be prevented by arranging the ridges of the linear projections formed on the transparent plate at an angle.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a plan view of a transparent plate used in the embodiment.

FIG. 3 is a cross-sectional view illustrating an example of the surface light source unit according to the embodiment.

FIG. 4 is a cross-sectional view of another example of the surface light source unit of the embodiment.

FIG. 5 is a cross-sectional view of a conventional device in which a liquid crystal display panel with increased brightness and a surface light source unit are combined.

FIG. 6 is a cross-sectional view of a conventional transparent plate for increasing brightness.

FIG. 7 is a plan view of the transparent plate shown in FIG. 6;

[Explanation of symbols]

 1 surface light source unit 3 liquid crystal display panel 10 transparent plate

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-123342 (JP, A) JP-A-3-200929 (JP, A) JP-A-3-45527 (JP, A) 53424 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1/13357 F21V 8/00 601 G09F 9/00 336 G09F 9/30-9/46 G02B 6/00

Claims (3)

(57) [Claims] 1. A surface light source unit which emits light of substantially constant luminance in a plane over the entire surface, and is disposed on a front surface of the surface light source unit,
A transparent plate having a large number of linear convex portions formed so that the cross-sectional shape is substantially triangular and their ridge lines are substantially parallel,
A liquid crystal display panel, wherein light from the surface light source unit is irradiated through the transparent plate, wherein a ridge line of a linear convex portion of the transparent plate is inclined with respect to a side of the liquid crystal display plate. A liquid crystal display device comprising: 2. The light source according to claim 1, wherein the surface light source unit includes a light guide, and a primary light source disposed opposite to an incident end face of the light guide, and transmits light from the primary light source incident from the incident end face. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a light guide type surface light source unit that emits light from the surface of the light guide while propagating through the light guide and serves as illumination light. 3. A light from a primary light source is made incident from an incident end face, and light incident from the incident end face is emitted from the light guide surface while propagating through the light guide body. A liquid crystal display device in which emitted light is applied to a liquid crystal display panel through a transparent plate having a large number of linear projections formed so that the cross-sectional shape is substantially triangular and the ridge lines are substantially parallel. And a ridge line of the linear convex portion of the transparent plate is inclined with respect to an incident end face of the light guide.