JPH0417963Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The present invention relates to a back lighting display device suitable for use in liquid crystal televisions, etc., and is particularly designed to improve the lighting effect by effectively utilizing light. This is what I did.

[Conventional technology]

Various back-illuminated display devices have been proposed in the past, in which the display section of the display board is illuminated from the rear, but one recent example is a display panel with liquid crystal display, as shown in Figures 5 and 6. 2. Description of the Related Art A small portable television device configured with a display device (hereinafter referred to as an LCD) is known. That is, this television device 1 is constructed by closing the front opening 2A of the case 2 with the LCD 3, and housing therein a tube bulb 4 as a light source and a light guide 5. 5
A light entrance part 6 consisting of a semicircular groove is formed on one side surface corresponding to the bulb 4, and the light from the bulb 4 that enters into the light guide 5 from this light entrance part 6 enters the light guide 5.
Stipple 7 consisting of a small V-shaped recess provided on the back side of
The light is reflected toward the front surface side, and illuminates the light-transmitting portion of the LCD 3, that is, the display portion 8 from behind.

Since the display section 8 of the LCD 3 constitutes a television screen, it has a large continuous area, which makes it difficult to illuminate the entire surface with uniform brightness.
The brightness of the far part decreases. Therefore, the density of the stippling 7 is usually increased as the distance from the bulb 6 increases, and the brightness of the distant part is increased.

[Problem that the invention attempts to solve]

However, in such a conventional display device, a part of the light incident on the light guide 5 exits from the back surface of the light guide 5 to the outside and becomes a loss. There was a problem with this point.
Therefore, as a way to solve such problems,
As shown in FIG. 7, the inner bottom surface of the case is made into a smooth reflective surface 10 by vapor deposition of A or the like. However, even in such a structure, the light 11 emitted from the back surface of the light guide 5 is reflected by the reflective surface 10 and directed to enter the light guide 5 again, but the incident angle i is changed due to refraction at the time of light emission. is small, and only a small amount of light is reflected like light 12 and re-enters into the light guide 5 like light 13. Further, the light 12 travels while being reflected between the reflective surface 10 and the back surface of the light guide, and does not come out to the front surface of the light guide 5, so that a sufficient illumination effect cannot be obtained. .

[Means for solving problems]

The display device according to the present invention was developed to solve the above-mentioned problems, and the inner bottom surface of the case is made into a step-shaped reflective surface, and this reflective surface reflects the light emitted to the back side of the light guide. The light is made to enter the light guide again.

[Effect]

In the present invention, since a step-shaped reflective surface is provided instead of a smooth reflective surface, the incident angle to the light guide can be increased, and the amount of light re-entering the light guide can be increased. Therefore, light can be used effectively and lighting effects can be improved.

〔Example〕

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 1 is a sectional view showing an embodiment of a display device according to the present invention, and FIG. 2 is a partially omitted plan view of a step-shaped reflective surface provided on the inner bottom surface of the case. In addition,
Components and parts that are the same as those in FIGS. 5 to 7 are designated by the same reference numerals, and their explanations will be omitted. In these figures, this embodiment has step-shaped (sawtooth-like) unevenness on the inner bottom surface of the case 2, and the unevenness is treated with A vapor deposition, white painting, etc., so that the inner bottom surface of the case has a step-like reflection. Side 2
The conventional device shown in FIGS. 5 to 7 differs in that it is 0, that a hemispherical light entrance part 6 is provided at the center of one end surface of the light guide 5, and that a general light bulb 4 is used as a light source. There is a difference between

The irregularities of the step-shaped reflective surface 20 are formed concentrically and regularly around the light bulb 4, and the step angle θ is constant, but is not limited to this, and gradually increases as the distance from the light bulb 4 increases. It may be something that gets bigger.

Thus, in a display device having such a configuration, the light that enters the light guide 5 and exits to the back side of the light guide beyond its critical angle (42.5° in the case of acrylic) is reflected by the step-shaped reflective surface 20. At this time, if the reflecting surface is flat, as explained in FIG.
is small, and the amount of light re-entering into the light guide 5 is small.
When it is set to 0, the angle of incidence on the light guide 5 increases due to the step angle θ, so that the amount of light re-entering the light guide 5 can be increased. Therefore, the light can be used effectively and the display section 8 of the LCD 3 can be illuminated even brighter.

FIG. 3 is a sectional view showing another embodiment of the present invention, and FIG. 4 is a perspective view of the case. In these figures, the light guide 5 is formed into a wedge shape so that the plate thickness is thickest at the end on the light entrance part side and gradually becomes thinner toward the end on the light entrance part 6 and the reflection side. The LCD 3 is disposed in the case 2 so that its surface side faces the LCD 3 in parallel. Like the light guide 5, the case 2 is made of a translucent material such as acrylic resin, and its inner bottom surface is inclined to face the back surface of the light guide 5, and has a step-shaped reflective surface 20. It consists of The step-shaped reflective surface 20 extends in the optical axis direction of the tube bulb 4 and is composed of a large number of chevron-shaped protrusions 21 arranged in parallel in a direction away from the bulb 4. The bulb 4 side slope of each protrusion 21 constitutes a reflective surface by vapor deposition of A, and the bulb 4
The slope on the opposite side is not subjected to any reflection treatment and forms a transparent portion 22.

The external shape of the side wall 23 on the side of the bulb 4 of the case 2 is such that light emitted from the bulb 4 in the opposite direction to the light guide 5 and incident on the side wall 23 is directed to the bottom surface 24 of the case 2.
The shape is said to be able to effectively lead to. In addition, a portion of the lower surface 25 of the case 2 that is far from the bulb 4 is inclined so as to be almost parallel to the inner bottom surface of the case, thereby reflecting the light 26 traveling inside the bottom surface portion 24 upward. ing. A part of this reflected light 26' is reflected by the step stripe reflecting surface 20.
The remaining light is reflected from the inner surface toward the lower surface 25 and exits from the transparent portion 22 to the outside and enters the light guide 5. That is, in this embodiment, by forming the case 2 from a light-transmitting material, it is possible to effectively utilize the light 26 emitted from the bulb 4 in the opposite direction to the light guide 5.

In this case, if the lower surface 25 is also provided with stipples 27 or step reflective surfaces 28, the lower surface 25
The amount of light emitted to the outside can be reduced.

[Effect of idea]

As described above, since the display device according to the present invention has a step-shaped reflective surface on the inside bottom of the case, the light emitted to the back side of the light guide is reflected at a large angle,
The angle of incidence on the light guide can be increased. Therefore, the amount of light re-entering from the back surface of the light guide increases, the light utilization efficiency improves, and the display section can be illuminated more brightly. Furthermore, the structure is extremely simple and easy to manufacture, and its practical effects are very large.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of a display device according to the present invention, FIG. 2 is a partially omitted plan view of a step-shaped reflective surface, and FIG. 3 is a sectional view showing another embodiment of the present invention. 4 is a perspective view of the case, FIG. 5 is an exploded perspective view showing a conventional example of a display device, FIG. 6 is a sectional view, and FIG. 7 is a diagram for explaining light reflection. 2... Case, 3... Display board, 4... Tubular bulb, 5... Light guide, 6... Light entrance part, 7... Stipple,
8...Display section, 20...Step-shaped reflective surface, 22
...The clear section.

Claims (1)

[Claims for Utility Model Registration] (1) A case, a display board having a translucent display section and disposed in the opening of the case, a light source disposed in the case, and a display plate disposed in the opening of the case, and a light guide having a light entrance part and guiding the light from the light source to the display part of the display board; A display device characterized by being provided with a step-shaped reflecting surface that causes light to re-enter. (2) Utility model registration claim No. 1, characterized in that the case is made of a translucent material, and the lower surface thereof constitutes a reflective surface that reflects the light traveling inside the case toward the display panel. The display device according to item 1.