JPH06163993A - Light source device - Google Patents

Abstract

PURPOSE:To obtain a light source device capable of uniform surface light emission without decreasing the brightness of the whole part of a light emitting surface. CONSTITUTION:A diffusion sheet 4 is arranged and turned into a light emitting surface, and a light emitting diode chip 1 is arranged on the rear of the sheet 4. A reflecting part 3B which cuts off the direct light from the light emitting diode chip 1 to the light emitting surface side and reflects the light is installed on a reflecting case 3 which leads out the light from the light emitting diode chip 1 to the light emitting surface side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light source device for surface emission, for example, a liquid crystal display panel (LC).
It is used as a backlight for D).

[0002]

2. Description of the Related Art Conventionally, a light source device used as a backlight for a liquid crystal display panel is constructed as shown in FIG. 7, 1 is a light emitting diode chip as a light source, and its anode and cathode sides are on a printed circuit board 2. Each pattern is attached with silver paste, wire-bonded, and then resin-molded.

Reference numeral 3 denotes a reflection case arranged on the printed circuit board 2. The reflection case 3 has a horn-shaped reflection surface 3A surrounding the periphery of the light emitting diode chip 1, and the light from the light emitting diode chip 1 is reflected. Is led out to the opening side of the horn-shaped reflecting surface 3A which serves as a light emitting surface.

Reference numeral 4 denotes a diffusion sheet which serves as a light-emitting surface and is arranged so as to cover the opening of the horn-shaped reflection surface 3A of the reflection case 3. On the diffusion sheet 4 (see the dotted line in FIG. 7). In addition, the liquid crystal display panel 5 as a light valve is arranged. Reference numeral 6 is a coating material that covers unnecessary portions of the liquid crystal display panel.

[0005]

However, in the light source device having such a structure, direct light from the light emitting diode chip causes unevenness of light emission on the light emitting surface, and particularly on the light emitting surface, a portion directly above the light emitting diode chip. Becomes too bright by direct light (see Fig. 8) and becomes a point emission state.
It has been a problem to use it as a backlight of a liquid crystal display panel that requires uniform surface emission.

If a diffusion sheet having a high degree of diffusion is used in order to alleviate point emission on the light emitting surface due to direct light from the light emitting diode chip, the entire light emitting surface will be darkened this time. Will occur.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light source device capable of substantially uniform surface emission without lowering the brightness of the entire light emitting surface. It is what

[0008]

To achieve the above object, in the present invention, a diffusion sheet is provided as a light emitting surface and a light source is provided on the back side thereof, and light from the light source is emitted by a reflection case. In the light source device led to the surface side, the reflecting case is provided with a reflecting portion that blocks and reflects the direct light from the light source to the light emitting surface side.

[0009]

According to this structure, since the direct light from the light emitting diode chip is blocked and reflected by the reflecting portion, the uneven light emission on the light emitting surface due to the direct light is eliminated and the direct light is emitted. Since the light is guided to the light emitting surface side as indirect light, the brightness of the entire light emitting surface does not decrease due to the provision of the reflecting portion.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. The same parts as those of the conventional one are designated by the same reference numerals and the description thereof will be omitted. In this embodiment, as shown in FIG. 1, FIG. 2 and FIG. 3, direct light from the light emitting diode chip 1 to the light emitting surface side is directed to the reflecting case 3 for guiding the light from the light emitting diode chip 1 to the light emitting surface side. A plate-shaped reflecting portion 3B for blocking and reflecting is provided.

Specifically, the reflection part 3B is integrally formed with a resin (for example, resin) such that the reflection part 3B is supported above the light emitting diode chip 1 by a crosspiece 3C so as not to directly emit light to the light emitting surface side, as shown in the figure. Modified PPO), and at least the plate surface side of the reflecting portion 3B facing the light emitting diode chip 1 is formed in a convex shape (in this case, the light emitting surface side is also formed in a concave parabolic shape. 3) Reflective surface 3
Like A, it is mirror-finished. In addition, in order to improve the light emission efficiency, it is assumed that the light emitting surface side of the reflecting portion 3B, the crosspiece 3C, and the like are also mirror-finished.

Therefore, in such a structure, the direct light from the light emitting diode chip 1 to the light emitting surface side is shielded by the reflecting portion 3B located almost directly above and reflected to the surroundings, for example, silk on the printed circuit board 2. The reflected light is reflected by the printed white resist, the reflective surface 3A, etc., and is guided to the light emitting surface side as indirect light. Therefore, only indirect light is emitted to the light emitting surface side, and it is possible to realize substantially uniform surface emission without uneven light emission due to direct light.

By doing so, although the brightness of the light emitting surface portion located directly above the light emitting diode chip 1 is somewhat lowered, it is alleviated because the surrounding area is brighter by that amount, and as a whole, It is possible to emit light substantially uniformly (see FIG. 4).

Next, FIG. 5 shows another structural example in which the reduction of the brightness of the light emitting surface portion located directly above the light emitting diode chip 1 is suppressed, and the reflecting portion 3B and the crosspiece 3 of the reflecting case 3 are shown.
By forming the hole 7 in C so that the light does not directly exit to the light emitting surface side, the light is easily guided to the light emitting surface portion immediately above.

In this embodiment, the case where the number of the light emitting diode chips is one has been described above. However, when it is desired to emit a brighter surface light or a larger light emitting surface, the number of the light emitting diode chips is increased and It suffices to use a reflective case having a reflective portion corresponding to the number of chips. For example, when it is desired to double the number of light emitting surfaces with substantially the same brightness, as shown in FIG. 6, two light emitting diode chips 1 and 1'are provided on the printed circuit board, and each of the chips 1 and 1'is provided. The reflection case 3 having the reflecting portions 3B and 3B ′ facing each other may be used.

[0016]

As described above, according to the light source device of the present invention, since only the indirect light is guided to the light emitting surface side to eliminate the uneven light emission due to the direct light, a substantially uniform surface light emission is achieved. Can be done. Further, since this is achieved only by changing the shape of the reflection case side, it can be easily realized without causing a large change in the manufacturing process or an increase in cost.

[Brief description of drawings]

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

FIG. 2 is a schematic side sectional view thereof.

FIG. 3 is a top view thereof.

FIG. 4 is a diagram showing a relationship between the light source position and brightness.

FIG. 5 is a diagram showing another embodiment.

FIG. 6 is a diagram showing another embodiment.

FIG. 7 is a schematic side sectional view showing a conventional example.

FIG. 8 is a diagram showing a relationship between the light source position and brightness.

[Explanation of symbols]

 1 Light-Emitting Diode Chip 3 Reflective Case 3B Reflector 3C Bar 4 Diffuser Sheet

Claims (1)

[Claims] 1. A light source device in which a diffusion sheet is provided as a light emitting surface and a light source is provided on the back side thereof, and the light from the light source is led out to the light emitting surface side by a reflection case, A light source device comprising a reflecting portion for blocking and reflecting direct light to the light emitting surface side.