JP2001318235A - Liquid crystal illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal illuminator which is satisfactory in durability, is easily made to emit light uniformly, has little light loss and has an inexpensive manufacturing cost. SOLUTION: The liquid crystal illuminator is provided with light transmission tubes 1 (1a-1c), arranged along peripheries of a liquid crystal displaying surface 10. On the one end face of the light transmission tube 1a a light source unit 11 is arranged. The light, outgoing from the other end face of the light transmission tube 1a, is reflected with a reflector 5a and made incident on the one end face of the light transmission tube 1b. The light, outgoing from the other end face of the light transmission tube 1b, reflected with a reflector 5b and made incident on the one end face of the light transmission tube 1c. On the other end face of the light transmission tube 1c a reflection body layer 7 is arranged. The incident light from the end faces of the respective light transmission tubes 1a, 1b, 1c is radiated from the peripheral side faces of the respective light transmission tubes 1a, 1b, 1c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a front light type liquid crystal lighting device for irradiating light to the front surface of a display surface of a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as portable terminals as lightweight and thin display devices. Since the liquid crystal display does not have a self-luminous function, a flat light emitter (backlight) is provided on the back of the liquid crystal, or an illumination device (front light) that irradiates light to the front of the liquid crystal display surface is used. The present invention relates to a liquid crystal lighting device called a front light.

Japanese Patent Application Laid-Open No. 2000-19514 uses a cold cathode tube as a light source, arranges a substantially semi-cylindrical reflecting plate (reflector) behind the cold cathode tube, and transmits light from the cold cathode tube to a plane reflecting plate. A front-light type liquid crystal lighting device that irradiates a liquid crystal display surface with a reflector having a concave shape in an arc shape is described.

An optical transmission tube having a tubular clad and a core made of a material having a higher refractive index than the constituent material of the tubular clad is used as a linear luminous body for emitting light from the side peripheral surface. Forming a strip-shaped reflective layer between the tubular clad and the core along the length direction of the tubular clad, and reflecting light passing through the core by the reflective layer.
In recent years, attention has been paid to a light transmission tube that is scattered and emitted from the outer peripheral surface of the tubular cladding side opposite to the side on which the reflective layer is formed. It is also known to change the width of the strip-shaped reflective layer in the length direction in order to make the amount of light emitted from the side peripheral surface of the linear light-emitting body uniform in the longitudinal direction (Japanese Patent Laid-Open No. 2000-39519). issue).

In this light transmission tube, a reflecting layer is formed in a band shape between the tubular cladding and the core along the length direction of the tube, and strong light passing through the core having the largest light intensity reflects the band-like reflection light. The light is reflected by the layer and emitted as strong light with high directivity from the tube-side peripheral surface opposite to the reflective layer. As a result, the brightness becomes extremely high and the brightness becomes very bright. By forming the band-shaped reflection layer so that the width gradually increases from one end side, which is the light incident portion of the light transmission tube, to the other end side, from the light transmission tube,
A substantially uniform amount of light can be emitted in the length direction.

[0006]

A liquid crystal lighting device using a cold cathode tube as a light source has the following disadvantages. An inverter for driving a cold cathode tube is required. Since the cold cathode tube has electrodes at both ends, light is not emitted from both ends. Therefore, the vicinity of both ends of the liquid crystal lighting device becomes dark. The cold-cathode tube has no directivity in the direction of light emission, requires a reflector (reflector), and is troublesome in mounting the reflector, which is expensive, and furthermore, the reflection loss at the reflector is considerable. large. The installation of the cold-cathode tube is troublesome, and requires a mounting member, which is costly. The durability of the cold cathode tube is not good. The cold-cathode tube has a slow lighting and extinguishing speed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal lighting device which solves such various problems, has excellent operation characteristics, is inexpensive, has good durability, and emits light uniformly over the whole.

[0008]

According to the present invention, there is provided a liquid crystal lighting device for irradiating light to a front surface of a liquid crystal display surface, wherein a light transmission tube extending along an edge of the liquid crystal display surface is provided. The light transmission tube is characterized in that light enters from one end and emits light from the side peripheral surface.

With such a liquid crystal lighting device, for example, by using a light emitting diode or the like as the light source of the light transmission tube, an inverter is not required and the turning on / off speed can be increased. The light transmission tube has extremely good durability.

[0010] In the present invention, the light transmission tubes are preferably arranged on a plurality of sides of the liquid crystal display surface. In this case, one light transmission tube may be provided over the adjacent side, or the light transmission tubes may be separately provided. When the light transmission tubes are separately arranged on adjacent sides, a light source may be provided for each light transmission tube, and a light source may be provided on one end surface of one light transmission tube, and the other end of the light transmission tube may be provided. The emitted light may be made incident on one end surface of an adjacent light transmission tube by a reflector. It is also possible to arrange three or more light transmission tubes in series and to arrange a reflector between the light transmission tubes so that light passes through each light transmission tube sequentially.

[0011] The light transmission tube used in the present invention may be composed of a core and a tubular cladding. Further, a strip-shaped reflection layer may be provided from the light incident portion to the end of the light transmission tube.

The optical transmission tube used in the present invention has a core and a tubular clad, and a strip-shaped reflective layer is formed between the tubular clad and the core along the longitudinal direction of the tubular clad. Preferably, the light passing through the core is reflected and scattered by the reflection layer and emitted from the outer peripheral surface of the tubular cladding opposite to the side where the reflection layer is formed.

By providing the reflection layer as described above, the reflector becomes unnecessary. In addition, light leakage is significantly reduced due to the lens effect of the cladding.

Since the light transmitting section of the light transmission tube extends over substantially the entire length, it is easy to uniformly emit light from the entire light guide plate. In order to fix the light transmission tube to the light guide plate, it is preferable to use a transparent adhesive.

In the case where one light transmission tube is continuously arranged over a plurality of sides, a bent portion generated in the light transmission tube at the corner of the liquid crystal display surface may be provided with a reflector layer over the entire circumference. Good.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of an optical transmission tube used in the liquid crystal lighting device according to the embodiment, and FIG.
3 is a cross-sectional view taken along the line III-III of FIG. 2, FIG. 4 is a perspective view of a lighting device used in the liquid crystal lighting device according to the embodiment, and FIG. FIG. 5 is a sectional view taken along the line V-V of FIG. FIG. 6 is a plan view of the liquid crystal lighting device according to the embodiment, and FIG. 7 is a sectional view taken along line VII-VII of FIG.

In this liquid crystal lighting device, a light transmission tube 1 (1a to 1c) arranged along the edge of a liquid crystal display surface 10 is provided.
Having.

In this embodiment, a light source unit 11 is provided on one end face of the light transmission tube 1a, and the light emitted from the other end face of the light transmission tube 1a is reflected by a reflector 5a so as to reflect the light. The light emitted from the other end of the light transmission tube 1b is reflected by the reflector 5b and is incident on one end of the light transmission tube 1c. A reflector layer 7 is provided on the other end surface of the light transmission tube 1c.

Light incident from one end surface of each of the light transmission tubes 1a, 1b, 1c is transmitted to the light transmission tubes 1a, 1b, 1c.
Radiated from the side peripheral surface of c.

The light reaching the other end surface of the light transmission tube 1c is reflected by the reflector layer 7 and is reflected by the light transmission tube 1c.
Because it is returned inside, there is no loss of light.

A light emitting diode is arranged in the light source unit 11. This light emitting diode may be one or one kind. In this embodiment, three light emitting diodes 12, 13, and 14 of red, blue, and yellow face the end face of the light transmission tube 1. Is provided.

The light transmission tube 1 has a band-shaped reflection layer 4 extending in the longitudinal direction of the tube between a core 2 and a tubular cladding 3 covering the core. The reflection layer 4 may be formed in a state in which the reflection layer 4 slightly penetrates into the core 3 from the surface of the core 3.

The reflection layer 4 is disposed on the side of the light transmission tube 1 opposite to the side from which light is to be emitted.
In this embodiment, the reflective layer 4 has a width that is about half the circumference of the core 2 of the light transmission tube 1, and light is hardly leaked from the reflective layer 4 side.

As the material (core material) forming the core 2, a transparent material having a higher refractive index than the material (cladding material) forming the tubular cladding 3 is used. Is appropriately selected and used depending on the purpose.

Specific examples of the core material include polystyrene,
Styrene / methyl methacrylate copolymer, (meth) acrylic resin, polymethylpentene, allyl glycol carbonate resin, spirane resin, amorphous polyolefin, polycarbonate, polyamide, polyarylate, polysulfone, polyallylsulfone, polyethersulfone, polyether Imide, polyimide, diallyl phthalate, fluororesin, polyester carbonate,
Transparent materials such as a norbornene-based resin (ARTON), an alicyclic acrylic resin (Optrez), a silicone resin, an acrylic rubber, and a silicone rubber can be used. .).

On the other hand, the clad material can be selected from transparent materials having a low refractive index, and examples thereof include organic materials such as plastics and elastomers.

Specific examples of the clad material include polyethylene, polypropylene, polymethyl methacrylate, polymethyl methacrylate fluoride, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyethylene-vinyl acetate copolymer, polyvinyl alcohol, and polyethylene. -Polyvinyl alcohol copolymer, fluororesin, silicone resin, natural rubber, polyisoprene rubber, polybutadiene rubber, styrene-butadiene copolymer, butyl rubber,
Halogenated butyl rubber, chloroprene rubber, acrylic rubber, ethylene-propylene-diene copolymer (EPD
M), acrylonitrile-butadiene copolymer, fluorine rubber, silicone rubber and the like.

Among the above core materials and clad materials, polystyrene, polycarbonate, styrene- (meth) acryl copolymer ( MS polymer) and the like, and the clad material is (meth)
Acrylic polymers are preferred.

The reflection layer contains a white pigment and a scattering material (meta).
It is preferable to use an acrylic polymer.

Examples of the white pigment and the scattering material include organic polymer particles such as silicone resin particles and polystyrene resin particles, metal oxide particles such as Al ₂ O ₃ , TiO ₂ and SiO ₂ , and sulfate particles such as BaSO _4. And carbonate particles such as CaCO _3, etc., and one of these can be used alone or in combination of two or more.

In consideration of the reflection efficiency, coextrusion workability, and the like, the average particle size of the particles of the white pigment and the scattering material is preferably about 0.1 to 200 μm, particularly preferably about 0.5 to 50 μm. The content in the reflective layer constituting material (reflective material) is about 0.5 to 20% by weight, particularly 1 to 10% by weight.
It is preferred that it is about.

Although the thickness of the reflection layer 4 is not particularly limited,
The thickness is preferably 0 to 200 μm, particularly preferably 50 to 100 μm. If the thickness is too small, the reflected light decreases and the luminance decreases.If the thickness is too large, the reflected light increases and the luminance increases. In some places, the brightness may be disadvantageously reduced.

The diameter of the core 2 is not particularly limited, but is usually about 2 to 30 mm, especially about 5 to 15 mm.
The wall thickness of the tubular cladding 3 is usually about 0.05 to 4 mm, especially about 0.2 to 2 mm.

In this light transmission tube, a reflective protective layer may be formed on the outer surface of the tubular cladding 3 so as to cover the peripheral surface that does not emit light (the peripheral surface on the reflective layer 4 side). In the case of an optical transmission tube having such a reflective protective layer formed thereon, when there is a defect such as a pinhole in the reflective layer 4, light leaking to the back side of the reflective layer 4 through this defective portion or the reflective layer 4 has By reflecting the light leaking from the side portion with the reflective protective layer, the loss of light can be reduced, and the brightness on the opposite side of the reflective layer 4 can be further increased.

As a constituent material of the reflective protective layer, a material that does not transmit the light leaked from the reflective layer 4 to the outside, does not absorb the light, and efficiently reflects the light is preferable. And a metal foil or metal sheet of silver, aluminum, or the like, or a coating film in which the above-described scattering particles that scatter light are dispersed.

To manufacture this light transmission tube, for example, a three-color extruder having three screw portions is used, and a core material, a clad material, and a reflecting material containing a white pigment or a scattering material are introduced into the extruder. The core material may be extruded into a cylindrical shape, the reflective material may be extruded into a plurality of strips on the outer peripheral surface of the columnar core material, and the clad material may be extruded into a tube shape covering the core material and the reflective material.

According to this method, three types of materials having different refractive indices and physical properties can be simultaneously extruded, and a laminated structure having three types of functions can be formed at a time.
Moreover, since the respective materials are laminated in a softened state, an optical transmission tube having excellent adhesion between the respective layers can be efficiently manufactured.

When a reflective protective layer is formed, a metal foil or a metal sheet may be adhered after the extrusion molding, or a coating material in which scattering particles are dispersed may be applied. It is also possible to form a hydrophilic protective layer.

The optical transmission tube may be manufactured by a method other than the above.

By lighting one, two or three of the light emitting diodes 12, 13, and 14, the light transmission tube 1 is turned on.
Can emit light of various colors. When only one light emitting diode 12, 13, 14 of the light source unit 11 is turned on, light of the color of the diode is radiated, and when two diodes are turned on, a light of an intermediate color in which they are mixed is emitted. Light is emitted and white light is emitted by turning on the three diodes.

Of course, as described above, only one or one type of light emitting diode may be provided.

In FIG. 6, light transmission tubes are provided only on three sides of the liquid crystal display surface 10, but light transmission tubes may be provided on four sides.

In the present invention, as shown in FIG.
Light source unit 11 on one end surface independently on each side of
The light transmission tubes 1a, 1b, 1c, 1d having the following may be arranged. Each optical transmission tube 1a, 1b, 1c, 1d
Is provided with a reflector layer 7 on the other end face. The configuration of the light transmission tube 1d is the same as the light transmission tubes 1a to 1c.
Note that, similarly to FIG. 6, the light transmission tubes may be provided only on three sides of the liquid crystal display surface.

In the present invention, as shown in FIG. 9, a continuous long light transmission tube 1e may be provided so as to go around the liquid crystal display surface. The light source unit 11 is provided on one end face of the light transmission tube 1e, and the reflector layer 7 is provided on the other end face. The light transmission tube 1e is connected to the liquid crystal display surface 1
In the place where it is bent at the corner of 0,
As shown in FIG. 10, the entire circumference of the light transmission tube 1e is
To prevent the corners of the liquid crystal display surface 10 from being illuminated excessively brightly or to prevent light leakage due to bending of the light transmission tube. The reflective material layer 8 is formed by, for example, attaching a metal foil such as aluminum or applying a paste containing a metal powder such as aluminum.

[0045]

The liquid crystal lighting device of the present invention uses a light transmission tube to emit light from a light source, and can easily and uniformly emit light over the entire surface of a liquid crystal display. Also, light loss can be reduced. In addition, by using a light emitting diode, lighting,
The light-off speed can be increased, and the amount of heat generated can be reduced. In addition, the light transmission tube has excellent durability, and has no risk of electric leakage even if it is cut, and is excellent in safety. The liquid crystal lighting device of the present invention is easy to manufacture,
It can be cheap.

[Brief description of the drawings]

FIG. 1 is a perspective view of an optical transmission tube used in an embodiment.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a sectional view taken along line III-III in FIG. 2;

FIG. 4 is a perspective view showing the liquid crystal lighting device according to the embodiment of the present invention.

FIG. 5 is a sectional view taken along line VV in FIG. 4;

FIG. 6 is a plan view of the liquid crystal lighting device according to the embodiment.

FIG. 7 is a sectional view taken along the line VII-VII in FIG. 6;

FIG. 8 is a plan view of a liquid crystal lighting device according to another embodiment.

FIG. 9 is a plan view of a liquid crystal lighting device according to yet another embodiment.

10 is a sectional view of a corner portion of the light transmission tube 1e of FIG.

[Explanation of symbols]

 1, 1a-1e Light transmission tube 2 Core 3 Tubular cladding 4 Reflective layer 5a, 5b Reflector 7 Reflector layer 8 Reflector layer 10 Liquid crystal display surface 11 Light source unit

Claims (10)

[Claims] 1. A liquid crystal lighting device for irradiating light to a front surface of a liquid crystal display surface, comprising a light transmission tube extending along an edge of the liquid crystal display surface, wherein the light transmission tube is configured to emit light from one end. The liquid crystal lighting device is characterized in that light is emitted from the side peripheral surface. 2. The liquid crystal lighting device according to claim 1, wherein the light transmission tubes are arranged on a plurality of sides of the liquid crystal display surface. 3. The liquid crystal lighting device according to claim 2, wherein one light transmission tube is arranged continuously on an adjacent side of the liquid crystal display surface. 4. The liquid crystal lighting device according to claim 3, wherein a reflection material layer is provided on the entire periphery of the light transmission tube at a corner of the liquid crystal display surface. 5. The liquid crystal lighting device according to claim 2, wherein separate light transmission tubes are arranged on adjacent sides, respectively. 6. The liquid crystal lighting device according to claim 5, wherein a light source is provided at one end of each light transmission tube, and a reflector layer is provided at the other end surface. 7. A light source according to claim 5, wherein a light source is provided at one end of one of the first light transmission tubes, and the light emitted from the other end of the first light transmission tube is reflected to be adjacent to the second light transmission tube.
A liquid crystal lighting device, further comprising a reflector that is incident on one end surface of the light transmission tube. 8. The liquid crystal lighting device according to claim 7, further comprising a reflector for making light emitted from the other end surface of the second light transmission tube incident on one end surface of the third light transmission tube. . 9. The liquid crystal lighting device according to claim 1, wherein a band-shaped reflection layer is provided from one end to the other end of the light transmission tube. 10. The optical transmission tube according to claim 9, wherein the light transmission tube has a core, and a tubular cladding surrounding the outer periphery of the core, and the band-shaped reflective layer is provided between the core and the tubular cladding. A liquid crystal lighting device, comprising: