JPH0876113A - Backlight and liquid crystal display - Google Patents

Abstract

(57) [Summary] [Object] To provide a liquid crystal display device which efficiently utilizes light from a fluorescent lamp. [Configuration] When the fluorescent lamp 4 is turned on, the glass bulb 5
While the light is emitted from the flat surface portion 5a, the light emitted in the direction of the curved surface portion 5b is reflected by the reflecting plate 6 and is emitted from the flat surface portion 5a, and is introduced into the light introduction portion 7a of the acrylic light guide 7. Light is guided by the acrylic light guide 7, an apparent light emitting surface is formed on the light diffusing plate, and the light from the light diffusing plate illuminates from the back surface of the liquid crystal display. [Effect] Since the facing surface of the fluorescent lamp 4 facing the light introducing portion 7a is the flat surface portion 5a and the light introducing portion 7a and the flat surface portion 5a are parallel to each other, the incident angle to the acrylic light guide 7 is small, The amount of light incident on the light introducing portion 7a at an acute angle can be increased, the amount of Fresnel reflection can be reduced, and the light emitted from the fluorescent lamp 4 can be efficiently introduced from the light introducing portion 7a, and the light efficiency can be improved.
Since the cross-sectional shape of the fluorescent lamp 4 approximates a circular cross-section, the discharge is stable.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art Conventionally, there is known a backlight for irradiating light from the back surface of a liquid crystal display body to irradiate the liquid crystal display body.

In recent years, this type of backlight has been widely adopted in consumer products and also used in office automation equipment. As the office automation equipment becomes lighter, thinner, shorter, and smaller, the backlight is also required to have high brightness, thinness, and light weight.

As a light emitting device having a higher light utilization efficiency than the conventional one, for example, Japanese Patent Laid-Open No. 7348/1990.
The configuration described in Japanese Patent Publication is known. This JP-A-2
No. 7348 discloses that the cross-sectional shape of the fluorescent lamp is flattened corresponding to the light introducing portion of the acrylic light guide, and the area of the fluorescent lamp facing the light introducing portion is widened to improve the light efficiency. ing.

[0005]

However, the positive column of the discharge generated in the fluorescent lamp becomes unstable as compared with the positive column of the fluorescent lamp having a circular cross section due to the pressure of the enclosed gas, the shape of the electrodes, and the like. May cause flicker.

Therefore, when the fluorescent lamp described in JP-A-2-7348 is used, there is a problem that the uniformity of brightness may be deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a backlight and a liquid crystal display device capable of stably discharging a fluorescent lamp and efficiently utilizing light.

[0008]

According to another aspect of the present invention, there is provided a backlight comprising: a light guide body having a planar light introducing portion on at least one end face side; and an outer surface of the light guide body facing the light introducing portion. In the flat plane portion, a portion other than the flat portion is provided with a fluorescent lamp which is a curved surface portion bent toward the flat portion.

The backlight according to claim 2 is the backlight according to claim 1.
The backlight described above is provided with a plurality of light diffusion plates arranged on the front side of the light guide.

The backlight according to claim 3 is the backlight according to claim 1.
Alternatively, the backlight according to the item 2 is provided with a light diffusing unit disposed on the rear surface side of the light guide.

The backlight according to claim 4 is the backlight according to claim 3.
The backlight described above includes a light reflector arranged so as to cover the light diffusing means.

The backlight according to claim 5 is the backlight according to claim 1.
In the backlight according to any one of items 1 to 4, the curved surface portion has an arc shape and has a reflecting surface on either one of the inner surface and the outer surface.

A liquid crystal display device according to a sixth aspect is the first aspect.
The backlight according to any one of items 1 to 5 and a liquid crystal display provided on the front side of the backlight.

[0014]

In the backlight according to the first aspect of the present invention, the shape of the fluorescent lamp is such that the outer surface of the light guide body facing the light introducing portion is a flat plane portion, and the portions other than the flat portion face the flat portion. Since the curved surface is curved, the cross-sectional shape approximates to a circular shape, which stabilizes the discharge, and the flat surface faces the light-introducing section, so the light from the fluorescent lamp is guided by the light guide. Since the amount of Fresnel reflection is reduced, the light from the phosphor can be used efficiently.

The backlight according to claim 2 is the backlight according to claim 1.
In the backlight described above, since the plurality of light diffusion plates are arranged on the front side of the light guide, the brightness can be made uniform.

The backlight according to claim 3 is the backlight according to claim 1.
Alternatively, in the backlight described in item 2, since the light diffusing means is arranged on the rear surface side of the light guide, the brightness can be made uniform.

The backlight according to claim 4 is the backlight according to claim 3.
The backlight described above includes a light reflector arranged so as to cover the light diffusing means.

The backlight according to claim 5 is the backlight according to claim 1.
In the backlight described, the curved portion has an arc shape,
Since the reflective surface is provided on the inner surface side or the outer surface side, the light from the surface of the fluorescent lamp that does not face the light guide can be efficiently used.

A liquid crystal display device according to a sixth aspect is the first aspect.
Alternatively, since the liquid crystal display is provided on the front side of the backlight described in 2, light can be efficiently used.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid crystal display device of the present invention will be described below with reference to the drawings.

In FIGS. 2 and 3, reference numeral 1 denotes a base body which constitutes a light reflector whose inner surface is mirror-finished, and the base body 1 has a rectangular shape in plan view, and both ends of the holding portion 2 and 2 are folded back into an arc shape.
Is formed, and an irradiation opening 3 having a rectangular opening is formed between the holding portions 2 and 2.

Further, straight tube fluorescent lamps 4 and 4 are disposed inside the holding portions 2 and 2 at both ends of the base body 1, respectively, and sandwiched and held by the holding portions 2.

As shown in FIG. 1, the fluorescent lamp 4 has a flat surface portion 5a having a linear cross-section on one end surface, and the flat surface portion 5a is formed on the opposite side of the flat surface portion 5a. A curved surface portion 5b formed of a quadratic curve that is open toward the portion 5a and curved toward the flat surface portion 5a is formed, and is formed into a substantially semi-cylindrical cross section, and the flat surface portion 5a extends in the longitudinal direction. A flat surface is formed, and a quadric surface along the longitudinal direction is formed in the curved surface portion 5b, and the inner surface is the circular portion 5c as in the conventional case.
It has a glass bulb 5. The curved surface 5b of the glass bulb 5 is provided with a reflection plate 6 having a reflection surface toward the inner surface.

Further, the holding portion 2 is formed with an arcuate curved surface 2b facing the curved surface portion 5b of the glass bulb 5 of the fluorescent lamp 4. Further, the inner surface of the substrate 1 is made of, for example, silver (Ag).
Alternatively, the substrate reflecting surface 1a is formed by processing it into a mirror surface by vapor deposition coating of aluminum (Al) or the like.

Further, so that the irradiation opening 3 is closed,
An acrylic light guide 7 having a substantially rectangular planar shape is attached, and light introducing portions 7a are formed at both ends of the acrylic light guiding body 7. The light introducing portions 7a are the same as the height of the flat portion 5a of the fluorescent lamp 4. They are formed at almost the same height.

A plurality of V-shaped grooves 7b serving as light diffusing means are formed in parallel with the fluorescent lamp 4 on the back surface which is the rear surface of the acrylic light guide 7. The light diffusing means may be a conical small hole or a means for adhering white ink.

Furthermore, on the front side of the acrylic light guide 7, two plate-shaped light diffusion plates 8 serving as a diffuser for diffusing the irradiation light from the back side are laminated and stacked. .
The front side, which is the surface of each of the light diffusion plates 8 and 8, is processed to be rougher than the back side, and also has the effect of a prism for condensing light.

On the front surface of the light diffusing plate 8, a liquid crystal display 9 for displaying with liquid crystal is provided. The liquid crystal array direction of the liquid crystal display 9 is set to be different from the acrylic light guide 7 by about 45 °.

Next, the operation of this liquid crystal display device will be described.

First, when the fluorescent lamp 4 is turned on, light is emitted from the flat portion 5a of the glass bulb 5 and the curved portion
The light radiated in the 5b direction is reflected by the reflection plate 6 and is reflected by the flat portion 5a.
And is introduced from the light introducing part 7a of the acrylic light guide 7. Then, in the acrylic light guide 7, light is guided to the entire acrylic light guide 7, and the apparent light emitting surface is provided with the light diffusion plate 8.
The liquid crystal display 9 is formed on the upper surface, and the liquid crystal display 9 is illuminated from the back by the light of the light diffusion plate 8.

Since unevenness of light is unlikely to occur on the light diffusing plate 8, the liquid crystal display body 9 is also illuminated from the back surface by the uniform irradiation light, and therefore is illuminated from the back surface by the uniform irradiation light. .

Further, the fluorescent lamp 4 facing the light introducing portion 7a.
Since the opposite surface of the glass bulb 5 is a flat surface portion 5a, and the light introducing portion 7a and the flat surface portion 5a are parallel to each other, the light emitted from the fluorescent lamp 4 is guided by an acrylic resin, as shown in FIG. The incident angle θ1 incident on the light body 7 is small, and as shown in FIG. 5, compared with the incident angle θ2 of the light radially irradiated by the conventional general fluorescent lamp 11 and incident on the acrylic light guide body 7. Since it is not so large, the amount of light incident on the light introducing portion 7a at an acute angle can be increased, the amount of Fresnel reflection can be made smaller than before, and the light emitted from the fluorescent lamp 4 can be efficiently emitted.
It can be introduced from 7a, and the efficiency of light can be improved.

The above-described embodiment is not limited to the liquid crystal display device, and the same effect can be obtained by using it as an escape guide light or sign lighting.

[0034]

According to the backlight of claim 1,
Since the outer surface of the fluorescent lamp facing the light introducing portion of the light guide is a flat plane portion, and the portion other than this flat portion is a curved portion bent toward this flat portion, the cross-sectional shape is Since the cross section is close to a circle, the discharge is stable and
Since the flat portion is opposed to the light introducing portion, the amount of Fresnel reflection of the light from the fluorescent lamp on the light guide decreases.
The light from the phosphor can be used efficiently.

According to the backlight of the second aspect, in addition to the backlight of the first aspect, since a plurality of light diffusing plates are arranged on the front side of the light guide, the brightness can be made uniform.

According to the backlight of the third aspect, in addition to the backlight of the first aspect or the second aspect, since the light diffusing means is arranged on the rear surface side of the light guide, the brightness can be made uniform.

According to the backlight of the fourth aspect, in addition to the backlight of the third aspect, a light reflector provided so as to cover the light diffusing means is provided.

According to the backlight of the fifth aspect, in addition to the backlight of the first aspect, since the curved portion has an arc shape and has a reflecting surface on the inner surface side or the outer surface side, it is used as a light guide for a fluorescent lamp. Light from non-opposing surfaces can also be used efficiently.

A liquid crystal display device according to a sixth aspect is the first aspect.
Alternatively, since the liquid crystal display is provided on the front side of the backlight described in 2, light can be efficiently used.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a liquid crystal display device of the present invention.

FIG. 2 is a side view of the same.

FIG. 3 is an exploded perspective view of the same.

FIG. 4 is a partial enlarged view showing an enlarged part of the same side surface.

FIG. 5 is an enlarged cross-sectional view showing a side surface of a conventional liquid crystal display device.

[Explanation of symbols]

 1 Base Material Constituting Light Reflector 4 Fluorescent Lamp 5a Flat Surface 5b Curved Surface 6 Reflective Plate Having Reflective Surface 7 Acrylic Light Guide 7a Light Introducing Section 7b Groove as Light Diffusing Means 8 Light Diffusing Plate 9 Liquid Crystal Display

Claims (6)

[Claims] 1. A light guide body having a planar light introducing portion on at least one end face side, and an outer surface of the light guide body facing the light introducing portion is a flat plane portion, and a portion other than the flat portion. Is equipped with a fluorescent lamp which is a curved surface portion curved toward the flat surface portion. 2. The backlight according to claim 1, further comprising a plurality of light diffusion plates arranged on the front surface side of the light guide. 3. The backlight according to claim 1, further comprising a light diffusing means provided on the rear surface side of the light guide. 4. The backlight according to claim 3, further comprising a light reflector provided so as to cover the light diffusing means. 5. The backlight according to claim 1, wherein the curved surface portion is arcuate and has a reflecting surface on either one of the inner surface and the outer surface. 6. A liquid crystal display device comprising: the backlight according to claim 1; and a liquid crystal display body arranged on the front side of the backlight.