CN103867965A - Backlight module - Google Patents

Abstract

The invention provides a backlight module, which comprises light sources and a diffusion sheet, wherein the diffusion sheet comprises a light-entering surface and a light-exiting surface; the light sources are arranged at one side of the light-entering surface of the diffusion sheet; the light-exiting surface of the diffusion sheet is provided with sub-wavelength gratings. According to the backlight module provided by the invention, by arranging the sub-wavelength gratings on the light-exiting surface of the diffusion sheet, light of which the incident angle reaches a critical angle of total reflection in the diffusion sheet can emerge out of the diffusion sheet through the diffraction action of each sub-wavelength grating, the loss of optical energy is reduced, and the light use efficiency of the backlight module is improved.

Description

Backlight module

Technical field

The present invention relates to backlight module.

Background technology

Because the liquid crystal in display panels itself is not luminous, for reaching display effect, need to provide a planar light source device to display panels, as backlight module, to realize real function.Existing backlight module generally comprises the element such as light source, diffuser plate, and wherein, diffuser plate is one of critical elements, and the light scattering diffusion that this diffuser plate can send light source, improves outgoing light homogeneity.But when the light that light source sends is penetrated by the exiting surface of diffuser plate after diffuser plate, owing to only being entered in the air dielectric that refractive index is less by the larger diffuser plate of refractive index, part light can not penetrate this diffuser plate because there is total reflection, thereby the light transmittance of diffuser plate is declined, reduce the efficiency of light energy utilization.

Summary of the invention

For overcoming the not high problem of the backlight module efficiency of light energy utilization in prior art, the invention provides a kind of backlight module that can improve the efficiency of light energy utilization.

A kind of backlight module comprises light source and diffusion sheet, and wherein this diffusion sheet comprises incidence surface and exiting surface, and this light source is arranged at a side of the incidence surface of this diffuser plate, on the exiting surface of this diffuser plate, is provided with sub-wave length grating.

Backlight module in the present invention arranges sub-wave length grating by the exiting surface at diffusion sheet, the light that makes incidence angle in diffuser plate reach the cirtical angle of total reflection can penetrate this diffuser plate by the diffraction of sub-wave length grating, reduce the loss of luminous energy, improved the efficiency of light energy utilization of backlight module.

Accompanying drawing explanation

Fig. 1 is the generalized section of backlight module in an embodiment of the present invention.

Fig. 2 is the schematic perspective view of diffusion sheet in the backlight module shown in Fig. 1.

Main element symbol description

Backlight module	100
		Light source	10
Diffuserplate	20
		Incidence surface	201
Exitingsurface	202
		Scattering particles	203
Sub-wave length grating	21

The following specific embodiment further illustrates the present invention in connection with above-mentioned accompanying drawing.

The specific embodiment

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

Please refer to Fig. 1 and Fig. 2, in the present invention's one preferred embodiments,backlight module 100 at least comprises at least onelight source 10 and adiffuser plate 20.

In the present embodiment, thislight source 10 is cold cathode fluorescent tube (Cold Cathode Fluorescent Lamp, CCFL).

Thisdiffuser plate 20 is tabular, and it comprises anincidence surface 201 and an exiting surface 202.Thislight source 10 is positioned at a side of theincidence surface 201 of this diffuser plate 20.In the present embodiment, the material of thisdiffuser plate 20 is transparent organic resin, as polymethyl methacrylate (Polymethyl Methacrylate, PMMA) or Merlon (Polycarbonate, PC).In thisdiffuser plate 20, be also dispersed withscattering particles 203, the light thatlight source 10 sends refraction, scattering and reflex throughscattering particles 203 afterincidence surface 201 is injected thisdiffuser plate 20 spread.

On theexiting surface 202 of thisdiffuser plate 20, be provided with the sub-wave length grating (Sub-Wavelength Gating) 21 of continuous distributed.After penetratingexiting surface 202, there is diffraction through this sub-wave length grating 21 in the light in diffuser plate 20.While ejaculation by theexiting surface 202 ofdiffuser plate 20 due to light, be to be entered in the medium that refractive index is less by the larger medium of refractive index, the incidence angle of part light can reach the critical angle of total reflection, and this sub-wave length grating 21 makes this part reach the light generation diffraction of the cirtical angle of total reflection, thereby diffraction goes out thisdiffuser plate 20, and there will not be the phenomenon that can not penetratediffuser plate 20 because of there is total reflection at exiting surface 202.In the present embodiment, thissub-wave length grating 21 is integrative-structures with thisdiffuser plate 20, thissub-wave length grating 21 is one dimension separate unit shape, its cycle is less than the light wavelength thatlight source 10 launches and is greater than 1/3rd wavelength of the light thatlight source 10 sends, and this sub-wave length grating 21 makes the light that exitingsurface 202 penetrates that-1 rank diffraction occur.Be understandable that, sub-wave length grating in present embodiment is a preferably embodiment, in other embodiments, this sub-wave length grating 21 can be also multidimensional, the shape of this grating also many shape pyramids etc. other form the structure of gratings, and the cycle of this grating can be to be also greater than other values in the scope of the light wavelength thatlight source 10 sends, this sub-wave length grating can be to be also fixedly installed on this diffuser plate exiting surface, and its effect is identical with the effect of one dimension separate unit shape sub-wave length grating in present embodiment.

Backlight module in the present invention arranges sub-wave length grating by the exiting surface at diffusion sheet, the light that makes incidence angle in diffuser plate reach the cirtical angle of total reflection also can penetrate this diffuser plate by the diffraction of sub-wave length grating, reduce the loss of luminous energy, improved the efficiency of light energy utilization of backlight module.

Although the preferred embodiment of the present invention is illustrated and is described, those skilled in the art will realize, and can make various changes and improvements, and these do not exceed true scope of the present invention.Therefore expect, the present invention is not limited to disclosed conduct and realizes the specific embodiment of the contemplated optimal mode of the present invention, and all embodiments that the present invention includes have in the protection domain of appended claims.

Claims (9)

1. a backlight module, comprises light source and diffuser plate, and this diffuser plate comprises incidence surface and exiting surface, and this light source is arranged at a side of the incidence surface of this diffuser plate, it is characterized in that, on the exiting surface of this diffuser plate, is provided with sub-wave length grating.

2. backlight module as claimed in claim 1, is characterized in that, this sub-wave length grating is one-dimensional grating structure.

3. backlight module as claimed in claim 1, is characterized in that, this sub-wave length grating is multidimensional optical grating construction.

4. backlight module as claimed in claim 2 or claim 3, is characterized in that, this sub-wave length grating is the separate unit shape grating of continuous distributed.

5. backlight module as claimed in claim 2 or claim 3, is characterized in that, this sub-wave length grating is many shape pyramid structures of continuous distributed.

6. backlight module as claimed in claim 1, is characterized in that, the cycle of this sub-wave length grating is less than light wavelength and is greater than 1/3rd wavelength of light.

7. backlight module as claimed in claim 1, is characterized in that, this sub-wave length grating and this diffuser plate are integrative-structures.

8. backlight module as claimed in claim 1, is characterized in that, the material of this diffuser plate is polymethyl methacrylate.

9. backlight module as claimed in claim 1, is characterized in that, the material of this diffuser plate is Merlon.

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