CN101718410A

CN101718410A - Method for preparing LCD backlight

Info

Publication number: CN101718410A
Application number: CN200910218897A
Authority: CN
Inventors: 宁铎; 吴涛; 王素娥; 张永佳; 金岩
Original assignee: Shaanxi University of Science and Technology
Current assignee: Shaanxi University of Science and Technology
Priority date: 2009-11-10
Filing date: 2009-11-10
Publication date: 2010-06-02

Abstract

The invention discloses a method for preparing an LCD backlight, which comprises the following steps: firstly, manufacturing a transparent board by adopting epoxy resin; and then setting LED line sources all around the board respectively, and setting refractive indexes of a light medium one, namely air and a light medium two, namely an epoxy resin board to be n and n/ respectively, wherein the incidence angle alpha of the LED line sources is the critical angle alpha0, and alpha0=arcsin (n//n). In the method, the combination of the LED line sources is used as the backlight; the line sources are converted into area sources according to the total reflection law and the reversibility principle of light, uniform backlight is provided for the LCD, and a condition of further reducing the thickness of the backlight is created.

Description

A kind of preparation method of LCD backlight

Technical field

The invention belongs to optical field, be specifically related to a kind of preparation method that can improve the backlight uniformity and reduce LCD (LCD) backlight of thickness.

Background technology

LCD (LCD) is widely used in fields such as television set and display with its good performance.But liquid crystal is a kind of material that is situated between between liquid and crystal, and itself is not luminous, but changes its molecules align state by voltage, promptly applies different voltage to liquid crystal and just can control the throughput of light, thereby show diversified image.Because liquid crystal itself can't be luminous, so all LCD need back lighting.The backlight of LCD nearly all is CCFL (ColdCathodeFluorescent Lamps, a cold-cathode fluorescence lamp) at present.

Because cold-cathode fluorescence lamp is not an area source, therefore in order to realize the uniform brightness output of backlight, the module backlight of the LCD numerous additional devices such as diffusion sheet, LGP, reflecting plate of also will arranging in pairs or groups, thus cause the complex structure of backlight, cost rises, and thickness increases.Nonetheless, obtain as the unusual difficulty still of the output of brightness uniformly as the CRT.When most of LCD deceives picture entirely in vain or entirely in demonstration, fairly obvious its outstanding defective that just becomes of the difference of screen edge and center brightness.Therefore when the LCD industry makes great efforts to open up new application, the high performance of backlight technology (as high brightness, high uniformity, low cost, low power consumption, lightening etc.) is very important.

Summary of the invention

The shortcoming that the objective of the invention is to overcome above-mentioned prior art provides a kind of total reflection principle and invertibity according to light, line source is transformed into the preparation method of the LCD backlight of area source.For achieving the above object, LCD backlight among the present invention is: at first, adopt epoxy resin to make transparent sheet material, around described sheet material the LED line source is set respectively then, the refractive index of establishing optical media one and be air and optical media two and be epoxy resin sheet material is respectively n and n ^/, the incidence angle α of this LED line source is critical angle α ₀, α ₀==arcsin (n ^// n),, can obtain uniform in-plane backlight effect according to the reversibility pricinple of light.

Since up and down and about the correlation structure of totally four line sources of each symmetry, thereby compensation has mutually solved in the present LCD display the little problem of screen edge brightness around the CCFL type backlight.And four line sources all install the version in the side of transparent sheet material, make that the thickness of backlight is reduced, for LCD display complete machine thickness reduces to have created condition.

As backlight, total reflection principle and invertibity according to light are transformed into area source to line source with the combination of LED line source in the present invention, thereby even backlight are provided and reduce its thickness for LCD.

Description of drawings

Fig. 1 utilizes the inverse process of light total reflection to realize that line source converts the principle schematic of area source to;

Fig. 2 is operation principle of the present invention and planar structure schematic diagram.

The specific embodiment

Below in conjunction with accompanying drawing the present invention is described in further detail.

Referring to Fig. 1, because some groups of LED type sources of parallel light are luminescence chip A, B, C, D, E, F and G when inciding epoxy resin and two kinds of light mediums of air interface with critical angle, can produce total reflection and form line source H, shown in (a) among Fig. 1.So according to the reversibility pricinple of geometric optics, placing one group of line source H that is made of LED in outgoing place injects parallel rays, to there be parallel rays A, B, C, D, E, F and G to form uniform surface light source equally, shown in (b) among Fig. 1 from positive evenly ejaculation of epoxide resin material.This method had both been saved numerous additional devices such as diffusion sheet in the backlight, LGP, reflecting plate, reduced the thickness of cost and backlight, (because LED group lamp does not increase thickness as the line source device in the side of epoxy resin), and realized the uniformity of backlight.

As backlight, certainly shooting angle α is the smaller the better, ideal situation is that vertical when α=0 to penetrate glass planar best, in fact because the optical material restriction, α is generally about 30 ° even bigger, but because about and the mutual compensation effect of this symmetrical structure up and down, guaranteed penetrating from the front uniformly of backlight.

If optical media 1 is air and optical media 2 is that the refractive index of epoxy resin is respectively n and n ^/, according to Snell's law:

sinα/sinα ^/＝＝n ^//n

So when total reflection takes place, refraction angle α ^/==90 °, at this moment Dui Ying incidence angle α is exactly critical angle α ₀So, can calculate: α ₀==arcsin (n ^// n)

For example to have added refractive index behind the titanium dioxide be that the epoxy resin of n=1.82 is as encapsulating material when selecting for use; Then in air, n ^/=1.0, so when epoxy resin and air interface generation total reflection, α ^/=90 °, the substitution following formula:

α＝33.7°

Promptly constitute led light source in the encapsulating structure as shown in Figure 1 for the material of above optical parametric, as long as when encapsulation, guarantee that the Line beam that luminescence chip sends enters epoxy resin in this way, then will be with the even outgoing of the critical angle α=33.7 ° angle of emergence, thus realize the LED line source is converted to area source.

In fact, in order to guarantee the uniformity of emergent ray, in this method, employing is total to four groups of line sources of device around this epoxy resin, through after compensating mutually, just can obtain even planar light source, specifically as shown in Figure 2 so at whole epoxy resin scope exit facet.Wherein (a) is symmetrical two groups of line source F2 and the light path schematic diagram of F1 under the total reflection situation, and they will compensate the back mutually with A2-E2 and two groups of directional lights of A1-E1 and form uniform backlight from the positive outgoing of epoxy resin; (b) then for about in the reality, about the structural representation of the novel LCD backlight formed of four groups of line sources and epoxy resin with total reflection function.

This by about, the uniform backlight that forms of laterally zygomorphic four groups of line sources both efficiently solved before the fairly obvious defective of difference of screen edge and center brightness in the CCFL structure backlight, effectively reduce the thickness of backlight again, become backlight technology very practical among a kind of LCD.

Claims

1. the preparation method of a LCD backlight, it is characterized in that: at first, adopt epoxy resin to make transparent sheet material, the LED line source is set respectively around described sheet material then, if optical media one is air and optical media two is that the refractive index of epoxy resin sheet material is respectively n and n ', and the incidence angle α of this LED line source is critical angle α ₀, α ₀==arcsin (n '/n),, can obtain uniform in-plane backlight effect according to the reversibility pricinple of light.