JP2572135Y2 - Light source device - Google Patents

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 diffusing and emitting light from a light source.

[0002]

2. Description of the Related Art As a light source device for irradiating a light receiving type display such as a liquid crystal display element with light, there is a diffusion type device which diffuses and emits light from a light source.

[0003] The diffusion-type light source device, conventionally, is constituted by placing a diffusion plate in front of the light source, as the diffuser, rough surface of the transparent plate made of glass or A click Lil resin A treated material, a material in which fine particles for diffusing light in a transparent plate are dispersed, and the like are used.

[0004]

However, in the above-mentioned conventional light source device, since the diffusion characteristic is determined by the type of the diffusion plate arranged in front of the light source, the diffusion state of the emitted light is constant, and therefore, It was not possible to change the directivity or the like of the luminance of the emitted light. An object of the present invention is to provide a light source device capable of arbitrarily changing the diffusion state of emitted light.

[0005]

Means for Solving the Problems The present invention of the light source device, in front of the light source, consists of a polymer dispersed liquid crystal layer are mixed a polymer and a liquid crystal between a pair of transparent substrates having transparent electrodes, before
The source light diffusion range depends on the voltage applied to the polymer liquid crystal layer.
Characterized in that a diffusion element for controlling the temperature is arranged.

[0006]

According to the present invention, the light from the light source is diffused by a diffusion element using a polymer dispersed liquid crystal. The molecules of the liquid crystal in the polymer dispersed liquid crystal layer of the diffusion element are formed on both substrates. In the state where no voltage is applied between the electrodes, the light is directed in various directions 2. In this state, light from the light source is scattered in the process of transmitting through the diffusion element, is diffused over a wide range, and exits the diffusion element. .

When a voltage is applied between the electrodes of the diffusion element, the liquid crystal molecules are arranged so as to be perpendicular to the substrate surface as the applied voltage is increased. The scattering effect of light by the dispersed liquid crystal layer is reduced, and therefore, the diffusion range of light emitted from the diffusion element is reduced. The diffusion range of the emitted light when this voltage is applied is:
It changes according to the applied voltage.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a light source device according to the present embodiment. FIG. 1A shows a state when no voltage is applied to the diffusion element, and FIG. 1B shows a state when a voltage is applied to the diffusion element. Is shown.

This light source device comprises a light source 1 and a panel-shaped diffusion element 10 disposed in front of the light source 1. The light source 1 is, for example, a plurality of rod-shaped fluorescent lamps 2 arranged in parallel.

In the diffusion element 10, a pair of transparent substrates (eg, glass plates) 11 and 12 having transparent electrodes 13 and 14 made of ITO or the like are arranged with their electrode forming surfaces facing each other. , 12 provided with a polymer-dispersed liquid crystal layer 16, wherein the substrates 11, 12 are joined via a frame-shaped sealing material 15.
Numeral 6 is provided in a region surrounded by the sealing material 15 over the entire region. Further, the transparent electrodes 13 and 14 on both surfaces of the substrates 11 and 12 are formed to have an area facing the entire region of the polymer dispersed liquid crystal layer 16. The polymer-dispersed liquid crystal layer 16 is a mixture of a transparent polymer 16a and a nematic liquid crystal 16b, as shown in FIG.

The polymer-dispersed liquid crystal layer 16 is formed by vacuum injection of a solution obtained by mixing a photocurable polymer monomer and liquid crystal in a region surrounded by the sealing material 15 between the substrates 11 and 12. The liquid crystal 16b is formed by a method of injecting light (ultraviolet light) from the outer surface side of one of the substrates and then photopolymerizing the polymer monomer to form a polymer. Polymerized polymer 16
a.

In this light source device, light from the light source 1 is diffused by the diffusion element 10 using polymer dispersed liquid crystal. The diffusion state of light emitted from the diffusion element 10 is Electrodes 1 on both substrates 11, 12
It can be changed arbitrarily by controlling the voltage applied between 3 and 14.

That is, the molecules of the liquid crystal 16b in the polymer dispersed liquid crystal layer 16 of the diffusion element 10 are
In the state where no voltage is applied between the electrodes 13 and 14, the light passes through the polymer dispersed liquid crystal layer 16 in various directions. The light is scattered by the light scattering action at the interface with 16a.

For this reason, in the state where no voltage is applied, the light from the light source 1 is scattered in the process of transmitting through the diffusion element 10, and
As shown by arrows in FIG. 1A, the light is diffused over a wide range and exits from the diffusion element 10.

Further, the electrodes 13 and 14 of the diffusion element 10 are used.
When a voltage is applied in between, the molecules of the liquid crystal 16b are arranged so as to be perpendicular to the surfaces of the substrates 11 and 12 as the applied voltage is increased. Since the light scattering effect is reduced, in this voltage applied state, the diffusion range of the light emitted from the diffusion element 10 is reduced as indicated by the arrow in FIG.

The diffusion range of the emitted light when the voltage is applied changes according to the applied voltage. That is, the diffusion element 1
As the voltage applied between the zero electrodes 13 and 14 is increased, the light scattering effect of the polymer dispersed liquid crystal layer 16 is reduced and the diffusion range of the emitted light is reduced.
FIG. 1B shows a state in which the diffusion range of the emitted light is the narrowest. In this case, all the liquid crystal molecules of the liquid crystal 16b are arranged substantially perpendicular to the surfaces of the substrates 11 and 12. I have.

Therefore, according to the light source device described above, by controlling the voltage applied between the electrodes 13 and 14 of the diffusion element 10, the diffused state of the emitted light is arbitrarily changed, and the directivity of the luminance of the emitted light is changed. Etc. can be controlled.

FIG. 3 shows a case where the above-described light source device is connected to a liquid crystal display device 20.
In this case, the viewing angle of the liquid crystal display device 20 can be changed by controlling the voltage applied to the diffusion element 10 of the light source device.

That is, when the display of the liquid crystal display device 20 is viewed from the front side, the viewing angle may be narrow. In this case, the diffusion element 10 of the light source device is set to a state where no voltage is applied or the applied voltage is reduced. In this case, the spread of the light emitted from the light source device may be narrowed. In this case, the spread of the light transmitted through the liquid crystal display device 20 is reduced as indicated by the solid arrow in FIG. High display can be obtained.

When the display on the liquid crystal display device 20 is viewed obliquely, the voltage applied to the diffusion element 10 of the light source device may be increased to widen the diffusion range of the light emitted from the light source device. By doing so, the liquid crystal display device 20
Since the spread of the light transmitted through is increased as shown by the dashed arrow in FIG. 3, the display image can be viewed from an oblique direction although the luminance slightly decreases.

Here, an example in which the light source device is used as a backlight of a liquid crystal display device has been described. It can be widely used as a light source device.

Further, in the above embodiment, the fluorescent lamp 2 is used as the light source 1, but this light source may be a point light source such as a palogen lamp or a tungsten lamp, or an EL (electroluminescence) panel or an LED (light emitting). A surface light source such as a diode) panel may be used.

[0024]

[Effect of the Invention] The light source device of the present invention uses the light from the light source,
Since the light is diffused by the diffusion element using the polymer dispersed liquid crystal in which the diffusion state of the light changes according to the applied voltage, the diffusion state of the emitted light can be changed arbitrarily.

[Brief description of the drawings]

FIG. 1 is a sectional view of a light source device according to an embodiment of the present invention, in which a voltage is not applied to a diffusion element and a voltage is applied to a diffusion element.

FIG. 2 is an enlarged cross-sectional view of a part of a polymer-dispersed liquid crystal layer of a diffusion element.

FIG. 3 is a cross-sectional view illustrating a state in which the light source device is used as a backlight of a liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Light source, 10 ... Diffusion element, 11, 12 ... Transparent substrate, 1
3, 14: transparent electrode, 16: polymer dispersed liquid crystal layer, 16a
... Polymer, 16b ... Liquid crystal, 20 ... Liquid crystal display device.

Claims (1)

(57) [Scope of request for utility model registration] 1. A light source device for diffusing and emitting light from a light source, comprising a polymer dispersed liquid crystal layer in which a polymer and a liquid crystal are mixed between a pair of transparent substrates having a transparent electrode, in front of the light source , Light is applied by a voltage applied to the polymer liquid crystal layer.
A light source device comprising a diffusion element for controlling a diffusion range of a source light.