A kind of back light system that comprises free-form surface reflector
Technical field
The present invention relates to a kind of back light system, particularly a kind of back light system that comprises free-form surface reflector
Technical background
In recent years, the market of flat-panel monitor is along with the development of consumption electronic product is increasing, and wherein, (Liquid Crystal Display LCD) accounts for the share of FPD near 90% to LCD.LCD is as a kind of passive luminescent device, and itself can be not luminous, for transmission type lcd device, must rely on back light that light is passed display floater, represents graph image.Cold-cathode tube (Cold Cathode Fluorescent Lamp, CCFL) and light emitting diode (Light Emitting Diodes LED) is two kinds of major techniques of present LCD backlight.CCFL backlight technology maturation wherein, various supporting optics are fairly perfect; The LED-backlit color reducibility is good, energy consumption is low, the life-span is long, response speed is fast, material does not have the environment public hazards, integral product is more frivolous, do not contain fragile part or the like.LED becomes LCD mainstream technology backlight just rapidly at present, and various backlight assemblies at the LED design are also more and more.
LCD is backlight to be divided into two kinds of Edge Lighting (side following formula) and DirectLighting (straight-down negative) according to its optical texture.The light source arrangement of side following formula is evenly distributed to light on the panel by Light Guide Plate (LGP) in LCD panel side, and the light source of straight-down negative directly is arranged in the liquid crystal panel below, does not need LGP.No matter be side following formula or direct-type backlight, all need optical thin films such as diffusion barrier, brightness enhancement film that uniform illumination is converted into and be suitable for the Luminance Distribution that spectators watch.In general, side down type LCD integral thickness backlight is thinner, is applicable to the small-medium size display; The directly-down type LCD light uniformity backlight height is not restricted by display sizes, is easy to realize dynamic area contrast control.
In the side down type LCD is backlight, the light of light source outgoing is coupled in the process of LGP, and the light energy loss can take place, LGP with the turn light rays of horizontal direction incident in the process of LCD panel direction, also there is energy loss, coupling efficiency and leaded light efficient have restricted the whole light efficiency of side type backlight jointly, in general, the whole light efficiency of actual side down type backlight system is not higher than 75%, is unfavorable for realizing energy-efficient display; And the leaded light area of LGP has certain limitation at present, and the leaded light area of monolithic LGP is generally less than 30 inches diagonal, and the oversize display will use the polylith LGP, has increased the difficulty of optical design and the complexity of system.
In the direct-type backlight, the fluorescent tube volume backlight owing to CCFL is bigger, generally uses the LED technology.
In direct-light type LED backlight, a kind of technical scheme has been used side-emitting led (Side Emitter LED) as described in U.S. Pat 6607286 and the US6679621, and the light energy of LED outgoing concentrates in the scope of horizontal direction ± 20 °.This based on side-emitting led back light system in, the inwall of backlight cavities is coated with highly reflective material, the light that LED sends interreflection in backlight cavities finally forms uniform light energy distribution at the panel place.This backing structure uniformity is higher, but light has lost a lot of energy in the process of interreflection, and whole light efficiency is on the low side, and integral thickness is also bigger than normal.Another kind of technical scheme is with LED distributed arranging below panel, because going out the space angle distribution of light energy, LED generally concentrates on axis direction, LED need with the LCD panel at a distance of certain distance, could guarantee that target face illumination is even, in general, the thickness of distribution type LED direct-type backlight is greater than the side light type LED backlight.In order to reduce the thickness of distribution type LED direct-type backlight, a kind of technical scheme is the density of arranging that increases the distributed LED of arranging, can reduce system's thickness to a certain extent, but this technical scheme can cause the number of LED sharply to increase, 22 cun panels use the number of LED to surpass 1000, can bring a series of problems such as light source uniformity, reliability, power drives; Another kind method is to use secondary lens to increase the LED rising angle, can reduce system's thickness equally, the existing at present free-form surface lens through the precision optics design is applied among the LED-backlit, but when being to use secondary lens to change the beam projecting direction, because the existence of total internal reflection, the beam projecting angle can not increase too much, and then the degree that reduces of back light system thickness is also limited, compares the side type backlight and also has certain gap.
Summary of the invention
The technical problem to be solved in the present invention is, provides a kind of illumination even, and entire system thickness is little, the light efficiency height, and be convenient to install the back light system that comprises free-form surface reflector with heat dissipation design.
For addressing the above problem, a kind of back light system that comprises free-form surface reflector of the present invention comprises: optical films such as light source, the optical sheet with semi-transparent semi-reflecting character, backlight cavities and diffusion barrier, brightness enhancement film.
Described backlight cavities is the cavity of a sealing, its bottom is for having the free form surface reflecting surface of high reflectance, backlight cavities is by the free form surface reflecting surface of sidewall with high reflectance and bottom and place the diffusion barrier at backlight cavities top to define jointly, be provided with optical film and LCD panels such as brightness enhancement film on diffusion barrier, wherein the reflectivity of backlight cavities sidewall and its bottom free form surface reflecting surface is greater than 70%;
Described light source is positioned at the backlight cavities bottom, is linear and arranges, and is installed on the axis of free form surface reflecting surface, and light direction is relative with the LCD panel; Be provided with an optical sheet with semi-transparent semi-reflecting character in the backlight cavities and be positioned at directly over the light source, its transmissivity and reflectivity are selected as required, and profile is tabular but is not limited to tabular, also can be profiles such as parabola, sphere.
The spectrum of the light emitted line of described light source should satisfy the requirement of the required backlight of liquid crystal panel, and it can be cold-cathode tube (CCFL) or light emitting diode (LED), if light source is LED, then can be white light LEDs or three primary colours (RGB) LED; If use white light LEDs, then each white light LEDs constitutes a back light unit (BLU); If adopt three primary colours (RGB) LED, redness then, a blueness, two greens totally four LEDs constitute a back light unit BLU, but the composition mode of different wave length LED is not limited to above form in back light unit; The packing forms of LED can be for containing surface patch encapsulation or other packing forms of lens.
If light source is CCFL, then its natural be linear light source; If light source is LED, then each back light unit (BLU) also should be linear arranging, and is installed on the axis of free form surface reflecting surface, and light direction is relative with the LCD panel.
Described free form surface reflecting surface can be the free form surface reflecting surface of one or more array arrangements in whole back light system; If use a plurality of free form surface reflectings surface of array arrangement, then each free form surface reflecting surface is corresponding to a backlight sub-chamber of independently sealing, the backlight sub-chamber close-packed array of a plurality of sealings is arranged and is constituted whole backlight cavities, or connects the backlight cavities of back corresponding to the sealing of an integral body by a plurality of free form surface reflectings surface.
For the uniform illumination of realizing the backlight cavities end face distributes, the effect of each optics is as follows in the system: most of light of light source outgoing directly arrives semi-transparent semi-reflecting optical sheet, and all the other fractions directly arrive the backlight cavities top; Arriving transmission in the light of semi-transparent semi-reflecting optical sheet partly passes semi-transparent semi-reflecting optical sheet and arrives the backlight cavities top, the reflecting part arrives the free form surface reflecting surface, the free form surface reflecting surface carries out secondary reflection to these light, finally also arrive the backlight cavities top, the uniform illumination that obtains the backlight cavities end face by its reflection direction of accurate control distributes; The backlight cavities sidewall also reflexes to the backlight cavities top with the light that small part does not arrive the backlight cavities top, to improve the uniformity of illuminance of backlight cavities end face;
Finally, optical films such as the diffusion barrier at backlight cavities top, brightness enhancement film are converted into required Luminance Distribution with the uniform illumination distribution.
Adopt a kind of back light system that comprises free-form surface reflector of the present invention, accurately controlling light reflection direction and the printing opacity by semi-transparent semi-reflecting optical sheet and reflection by the free form surface reflecting surface makes light source be positioned at the backlight cavities bottom, it is even to have illumination, entire system thickness is little, the light efficiency height, and be convenient to install advantage with heat dissipation design.
Description of drawings
Fig. 1 is the structural representation of first kind of specific embodiment of the present invention.
Fig. 2 is the cutaway view of Fig. 1 along the A-A direction;
Fig. 3 is the structural representation of second kind of specific embodiment of the present invention.
Fig. 4 is the cutaway view of Fig. 3 along the A-A direction;
Fig. 5 is the symbol TV structure schematic diagram of the third specific embodiment of the present invention.
Fig. 6 is the cutaway view of Fig. 5 along the A-A direction.
Fig. 7 is the structural representation of the 4th kind of specific embodiment of the present invention.
Fig. 8 is the cutaway view of Fig. 7 along the A-A direction.
The specific embodiment
Further specify embodiments of the invention below in conjunction with accompanying drawing:
Embodiment 1
As depicted in figs. 1 and 2, a kind of back light system that comprises free-form surface reflector comprises: light source 1, backlight cavities 3, the optical sheet 4 with semi-transparent semi-reflecting character, and diffusion barrier 5, ground floor brightness enhancement film 61 and second layer brightness enhancement film 62.
Described backlight cavities 3 is the cavity of a sealing, its bottom is for having the free form surface reflecting surface 2 of high reflectance, backlight cavities 3 is by the free form surface reflecting surface 2 of sidewall with high reflectance and bottom and place the diffusion barrier 5 at backlight cavities 3 tops to define jointly, is provided with ground floor brightness enhancement film 61 and second layer brightness enhancement film 62 and LCD panel on diffusion barrier 5; Wherein the reflectivity of the free form surface reflecting surface 2 of backlight cavities 3 sidewalls and its bottom is greater than 70%;
Light source 1 described in the present embodiment is a white light LEDs, every white light LEDs is formed a back light unit, each back light unit is linear arranges, be installed on the axis of backlight cavities 3 bottom free form surface reflectings surface 2, light direction is relative with the LCD panel, places the optical sheet with semi-transparent semi-reflecting character 4 in the backlight cavities 3 to be positioned at directly over the light source 1; Trends by free form surface reflecting surface 2 common control light source 1 emergent raies of semi-transparent semi-reflecting optical sheet 4, the sidewall of backlight cavities 3 and bottom with high refractive index, forming uniform illumination at backlight cavities 3 end faces distributes, finally, optical films such as the diffusion barrier 5 at backlight cavities 3 tops, ground floor brightness enhancement film 61, second layer brightness enhancement film 62 are converted into required Luminance Distribution with the uniform illumination distribution.
Embodiment 2
As shown in Figure 3 and Figure 4, a kind of back light system that comprises free-form surface reflector comprises: light source 1, backlight cavities 3, the optical sheet 4 with semi-transparent semi-reflecting character, and diffusion barrier 5, first brightness enhancement film 61 and second brightness enhancement film 62; Overall structure is similar to embodiment 1, and the main distinction is: the light source 1 in the present embodiment is cold-cathode tube (CCFL);
Embodiment 3
As Fig. 5, shown in Figure 6, a kind of back light system that comprises free-form surface reflector comprises: light source 1, backlight cavities 3, the optical sheet 4 with semi-transparent semi-reflecting character, and diffusion barrier 5, first brightness enhancement film 61 and second brightness enhancement film 62; Overall structure is similar to embodiment 1, and the main distinction is:
Light source 1 in the present embodiment is a three-primary color LED, by a red LED 11, a blue led 12, two green LED 13 totally four LEDs constitute a back light unit BLU, each back light unit is linear arranges, be installed on the axis of backlight cavities 3 bottom free form surface reflectings surface 2, light direction is relative with the LCD panel.
Embodiment 4
As shown in Figure 7 and Figure 8, a kind of back light system that comprises free-form surface reflector comprises: light source 1, backlight cavities 3, the optical sheet 4 with semi-transparent semi-reflecting character, and diffusion barrier 5, first brightness enhancement film 61 and second brightness enhancement film 62; Described backlight cavities 3 is made of the backlight sub-chamber 31 of 2 * 1 array arrangements.
Each sub-chamber 31 backlight is the cavity of a sealing, it is by the free form surface reflecting surface 21 of sidewall with high reflectance and bottom and place the diffusion barrier 5 at backlight cavities 3 tops to define jointly, be provided with ground floor brightness enhancement film 61 and second layer brightness enhancement film 62 and LCD panel on diffusion barrier 5, wherein the reflectivity of the sidewall in free form surface reflecting surface 21 and sub-chamber 31 backlight is greater than 70%.
Light source 1 described in the present embodiment is a white light LEDs, and every white light LEDs is formed a back light unit, and each back light unit is linear arranges, and is installed on the axis of sub-chamber backlight 31 bottom free form surface reflectings surface 21, and light direction is relative with the LCD panel; Place the optical sheet with semi-transparent semi-reflecting character 4 in the sub-chamber 31 backlight to be positioned at directly over the light source 1; By the trends of free form surface reflecting surface 21 common control light source 1 emergent raies of semi-transparent semi-reflecting optical sheet 4, the sidewall in backlight sub-chamber 31 with high refractive index and bottom, two zone combinations that uniform illumination distributes form uniform illumination at backlight cavities 3 end faces and distribute; Optical films such as diffusion barrier 5, first brightness enhancement film 61, second brightness enhancement film 62 place on the backlight cavities 3, and uniform illumination is distributed is converted into required Luminance Distribution.