CN1693968A - LED backlight system for packaging LED using six-color element - Google Patents

The invention discloses a LCD weakening light system of six colors (R1,R2,G1,G2,B1,B2) unit sealed LED and includes a light source module, a reflecting box and a light blender. The light source module contains several light source parts composed of six-color LED chips. One LED chip is sealed in one unit parts and then the part is arranged to form a light source. Moreover, the six-color chip of every LED light source can be driven independently to guarantee that the six-color lights have the temperature and brightness required when it arrives at the weakening light system. The lights can be mixed in a unit sealed. The light blender is a light transmission plank of refraction and diffraction admixture. The plank is a light refraction component and its surface has tiny stair array structure. To gain more uniform light, use different dispersion layers or brightness increasing films.

A kind of LCD back light system that uses the six-color element packaged LED

Technical field

The present invention relates to a kind of back light system of semiconductor light sources, be specifically related to the LCD back light that uses the six-color element packaged LED and use light uniforming device, Preparation Method And The Use.

Technical background

Along with the technology of ultra-bright LED is ripe gradually, price constantly descends, and because of it adopts three-color light-emitting, color reductibility is good, power consumption is low, adds advantages such as long and short little frivolous, environmental protection of life-span, it replaces the CCFL backlight gradually, has demonstrated great potential in field of liquid crystal display.

Because brightness is low, LED in the past can only be limited on the miniscope as the use of backlight.Along with the fast development of semiconductor technology, add the new ideas of package design, brightness and the efficient of LED are significantly improved, and the range of application in LED-backlit source is more extensive.

LED is that a kind of noticeable LCD backlight is selected, and especially when constituting white with red, green, blue LED, can improve display screen preceding color and brightness characteristics.If as the LCD backlight, can obtain three spectrum compositions around its predominant wavelength by design with primitive colours LED; And can shield inferior pixel by LCD and eliminate its all spectrum outside peak value spectrum, thereby when enlarging the color reproduction rate, can also realize high brightness, thus more superior than CCFL in this respect.

Because it is different that the colour temperature that dialogue fields such as multimedia, TV and graphical arts show requires, this just need regulate white colour temperature according to circumstances; But the LCD that with CCFL is backlight is difficult to control the spectral distribution of its backlight, and in order to obtain the good control to white colour temperature, must sacrifice the color reproduction gray scale dynamic range of LCD.But LED can control white colour temperature by the brightness of every kind of color LED of darkening respectively, thereby will win CCFL one undoubtedly in this respect and raise.

Be generally the serviceable life of large-scale LCD screen 5～60,000 hours, and the life-span of CCFL backlight generally has only 20,000 hours at present.The theoretical life-span of LED product is 100,000 hours, considers other factors, and be 5～60,000 hours actual life, and this just is complementary with the requirement of LCD display.

Up to the present, it is very few to do the enterprise that large scale liquid crystal shows with the LED-backlit source in the world.And the large scale liquid crystal demonstration aspect, LED-backlit source or the blank out of China.

As backlight, LED can roughly be divided three classes: white, monochrome and polychrome.

When using White LED backlight, circuit is simple relatively.But because its principle of sending white light is: the blue light part that chip sends changes gold-tinted into by media; Blue light and gold-tinted are mixed just to have produced white light, and chromaticity coordinates (white point) depends on the ratio of blue light and gold-tinted.The color range of display screen is restricted, and white colour temperature fixes, and is identical with CCFL.

Use that the RGB of monochromatic LED is backlight also to have shown special shortcoming: because each color is arranged alternately, just need the required space of additive color mixing, produce uniformly mixed light.The size in this colour mixture district depends on two distances between the homochromy LED and their emission angle.For the module that has light guide plate, the surface of light guide plate must increase; And for the reflective box structure, then thickness must increase.

By contrast, multi-colored led and colour mixture White LED is to occur in its encapsulating structure, and therefore, it is just much smaller that the emission characteristics of light is compensated required space.

On the whole, among the three class LED, multi-colored led is the optimal selection of colored display backlight.

In order further to enlarge color expression range, be not limited to R (red) in the past, green (G), B (indigo plant) 3 primary colors, can realize multicolor by appending new color, make lcd screen have broader colour gamut.

Because LED is a pointolite, radiation pattern is conical, so the key of LED-backlit is to obtain a surface of evenly illuminating.The main flow of LED-backlit system is the side light type LED back light source of adopting monochromatic LED light source+light guide plate at present.

Light guide plate is to improve the effective ways of color homogeneity, but owing in the process that light is propagated loss is arranged in plate, it is lower to the utilization factor of light.If target is a televisor, its brightness should reach 400～500cd/m at least ²Thereby, be better than using the scheme of light guide plate with LED scheme of direct illumination after lcd screen in order to obtain high brightness.

Chinese patent 200410048713.3 provides a kind of backlight combination and has the LCD of this backlight assembly, is side-light type back light, and does not specify employed light source; Patent 03106671.2 described backlight is arranged on the rear side of irradiated body, and its light source is made of the light emitting diode of any color in green, blue-green, blueness, orange, red, the yellow green, and its liquid crystal indicator is the white and black displays type; Chinese patent 02152111.5 described backlight is to use the side-light type back light of a plurality of light emitting diodes, and does not propose to use multi-colored led as light source.Also have CN1558284, CN1383501 and JP8-211361, the LED that these backlight assemblies or system use arranges monochromatic chip according to certain rule, carry out mixed light then and obtain white light.The shortcoming of this method is to need the distance of certain size to come mixed light, otherwise can not obtain the comparison uniform white light.Another patented claim of the inventor, application number is 200510034629.9, the applying date is on May 20th, 2005, this patent provides the LCD back light system of a kind of use three primary colours (RGB) packaged LED, the led chip of red, green, blue three primary colours is encapsulated in the unit component, then this unit component is arranged and formed light source, and use light uniforming device.In other words, in the back light system of prior art, neither one uses the device of six look LED in a unit; Do not make the refraction of using up and the light uniforming device of diffraction simultaneously yet.

Summary of the invention

The object of the present invention is to provide a kind of LCD back light system of use six looks (R1, R2, G1, G2, B1, B2) packaged LED.Back light system of the present invention comprises light source module, reflective box and light uniforming device, wherein said light source module comprises a plurality of light source devices, each light source device is made of the led chip of six looks, and the led chip of six looks is encapsulated in the unit component, this unit component is arranged formed light source then.

Another object of the present invention provides a kind of back light system of six-color element packaged LED, wherein six of each led light source kinds of color chips can drive be controlled, so that each color light meets the requirements of colour temperature behind the preliminary mixed light in the structure of unit package and brightness is transmitted into back light system again, thereby realize the high color rendering index (CRI) and the high brightness of LCD back light system.And six color chips that encapsulate in each led light source are when rated operational current, and the scope that peak wavelength can be selected is respectively: 410～420nm, 425～435nm, 500～520nm, 530～550nm, 605～618nm, 620～230nm.Also can and use needs to determine coupling between the optics/electrical specification (as luminous flux, light intensity and drive current, voltage etc.) of each color chip according to different design proposals; The encapsulating structure of led light source (comprising electrical structure, optical texture, physical construction) is also determined according to different design proposals and use needs.

Further object of the present invention provides a kind of back light system, wherein uses light uniforming device, comprises rolling over the mixed light guide plate of spreading out, and is placed in the one side of reflective box opening, thereby obtains uniform light on the ejaculation surface of light.Described folding spreads out, and to pull matrix itself be photorefractive element to mixed leaded light, and there is small ladder array structure on its surface, thereby constitutes the micro optical array that obtains optical diffraction.

Present carry out the back light source system of mixed light, need the strict coupling of performances such as luminous flux of each LED, and mixed light, light-conducting system are required high, be easy to occur defectives such as mixed light is inhomogeneous, colour temperature deviation by a plurality of RGB monochromatic LEDs.

And the six look LED-backlit sources of using are compared with using R (red), green (G), B (indigo plant) 3 primary colors, allow liquid crystal panel that bigger color expression range is arranged.

Using the LCD back light system of six-color element encapsulated LED light source is the direct backlight structure, after promptly six-color element encapsulated LED light source is arranged, makes the rear surface of light direct irradiation liquid crystal panel.The structure of back light system comprises light source module 1, reflective box 2 and light uniforming device 3.Light source module by several above-mentioned six-color element encapsulated LED light sources 11 according to certain rules, certain spacing arrangement on same plane, these led light sources form the luminous dot matrix that optical axis direction is parallel to each other.Described certain rule and spacing be meant according to customer requirements and select, and being actually does not have strict restriction.In a preferred embodiment, place light source module and make luminous dot matrix be positioned at reflective box 2, the light that dot matrix sends is mixed in the reflective box internal reflection.LED dot matrix by the spacing rule is arranged and reflective box with respective depth realizes even illumination on the display surface.The degree of depth of reflective box depends primarily on spacing and the emission angle of LED.Obtain further homogenising light, available different scattering layer or special brightness enhancement film (BEF), these all are market products on sale, also are well-known to those skilled in the art.If to the suitable in addition combination of different films, can reduce the degree of depth of reflective box.Direct backlight needing to be mainly used in high brightness (＞500cd/m ²), in the limited system in medium size and space.

Adopt direct LED-backlit scheme, the homogeneity of color remains key issue.Usually, LED arranges and closely helps colour mixture, and that still arranges is tight more, and thermal source is just concentrated more, needs complicated radiator structure.If the LED spacing is big, just favourable many to heat radiation, but the even problem that becomes again of irregular colour.Between color and heat, reach a balance by suitable design.The present invention adopts the six-color element packaged LED and adopts light uniforming device just to solve this problem well.Unit package makes and significantly reduces light mixing distance by mixed light as early as possible.Prior art only is that monochromatic LED is arranged according to rule, is a kind of whole mixed light, and then light mixing distance is very big.With regard to light mixing distance, compare with prior art, under the identical situation of light-mixing structure, the present invention can shorten 3.5 times; If the prior art mixed light needs 28mm, the present invention only needs 8mm.This is significant to the thickness that reduces the finished product instrument.In addition, owing to used light uniforming device, not only obtain light more uniformly, and guaranteed colour temperature.Moreover each led chip can be controlled separately, makes color undistorted.

Light uniforming device of the present invention is a kind of binary optical elements (Binary Optical Elements writes a Chinese character in simplified form BOE), and it is a kind of diffraction optical element of phase-type; With the diffraction of light effect is basic functional principle, adopts the element that the analysis of optical wave-front is designed diffraction position phase profile.The ultimate principle of binary optical, from the viewpoint of wave optics, require to be designed to a micro-embossment structure of binary with computing machine according to optical wave-front exactly, its dimension of picture is less than light wavelength, and then utilize microfabrication branch art, on medium or metallic substrates, be etched into device.The method of making binary optical elements mainly contains etching method, the coating method in the microelectronic technique, high precision diamond lathe programmed control cutting method etc. at present.Wherein the etching method in the microelectronic process engineering is the main means that adopt at present.Because the position phase profile that goes out of actual fabrication is serve as to quantize multiple with 2, with desirable continuous mutually the step shape of profile be similar to, so be called as " binary optical elements ".About the principle of light uniforming device and another patented claim of the visible inventor of structure, application number is to submit on May 20th, 200510034628.4,2005, and title is " a kind of led light source that uses light uniforming device ", and its content this paper is in conjunction with quoting.

Description of drawings

Fig. 1 is the structural representation of an embodiment of LCD back light system of the present invention.

Fig. 2 is the structural representation of six-color element encapsulated LED light source of the present invention.

Fig. 3 is the plan view from above of six-color element encapsulated LED light source of the present invention.

Fig. 4 is the synoptic diagram of the light source module of LCD back light system.

Fig. 5 is the synoptic diagram of the reflective box of LCD back light system.

Fig. 6 is the structural representation of another embodiment of LCD back light system of the present invention.

Fig. 7 is the principle schematic of rolling over the mixed light guide plate of spreading out in the LCD back light system of the present invention.

Fig. 8 is the spread out synoptic diagram of mixed light guide plate of the folding that has some grooves.

Fig. 9,10, the 11st, LCD back light system of the present invention is the structural representation of several embodiment in addition.

Embodiment

Be described in further detail the present invention with reference to the accompanying drawings in conjunction with the embodiments.

Embodiment one

For example, lcd screen for 15 inches, screen diagonal length is 381mm, aspect ratio is 3: 4, its height, wide 229mm and the 306mm of being respectively set LED and are arranged in parallel, and row, column is 18mm at interval, luminous lattice dimensions is 234mm * 306mm, and led light source quantity is 14 * 18=252; For 17 inches lcd screen, screen diagonal length is 443mm, and aspect ratio is 3: 4, its height, wide 271mm and the 338mm of being respectively set LED and are arranged in parallel, and row, column is 18mm at interval, luminous lattice dimensions is 270mm * 342mm, and led light source quantity is 16 * 20=320;

In this example, LED is arranged in parallel on aluminum base PCB, and row, column is spaced apart 18mm.In order to strengthen heat radiation, the aluminum base PCB back side can connect heating radiator.

When above-described back light system is worked, six-color element encapsulated LED array need provide suitable current by driving circuit by showing in the light source module, the mixed light that sends enters reflective box, in reflective box, reflect and further mixed, shine then on the incidence surface of scattering layer, through diffusion, obtain the suitable light of uniform colour temperature from outgoing plane, thereby provide desirable back lighting to lcd screen.

In the above-mentioned back light system, because what light source used is the six-color element encapsulated LED, colour mixture is to occur in its encapsulating structure, mixed through the reflection of reflective box again, through the scattering layer diffusion, can satisfy LCD needs backlight after the emission characteristics of light compensated, and no longer need to utilize light guide plate to carry out mixed light, reduced light loss, and the structure of LCD back light system is greatly simplified, cost reduces greatly.

Obtain further homogenising light, available different scattering layer or special brightness enhancement film (BEF).To the suitable in addition combination of different films, can reduce the degree of depth of reflective box.To in following embodiment, illustrate.

Embodiment two

The light source module of LCD back light system is identical with embodiment one.

The folding hybrid system of spreading out is to be combined by diffraction optical device and traditional diffractive optical devices, and promptly the sheet primary surface is made diffraction optical device 32a, and the basic body of sheet is made refraction optical element 32b.Specifically, light guide plate itself is a refracting element, in the more well-designed micro optical array structures of the light exit surface of light guide plate, as shown in Figure 7.The aperture, unit is of a size of micron dimension, thereby has had diffraction element on the light guide plate surface, utilizes the refraction and the opposite effect (Abbe number negative sense) of two kinds of optical effects of diffraction in chromatic dispersion, and color difference eliminating is widened colour gamut effectively, improves color reproduction.

Roll over the hybrid system of spreading out and utilized the refraction and diffraction two specific characters of light simultaneously; Have unique chromatic dispersion character, good thermal behavior and monochromatic aberration calibration capability; In optical design, increase the degree of freedom of design; Multi-functional integrated, reduce volume and reduce cost; The dispersion characteristics of diffraction optical lens uniqueness can be used for achromatism.

In the above-mentioned back light system, roll over the mixed light guide plate of spreading out, the mixed effect of light is strengthened, reduced the mixed required space of light, therefore can reduce the degree of depth of reflective box, thereby the thickness of LCD back light system is reduced owing to used.

Embodiment three

Because LED directly embeds the groove on the incidence surface of light guide plate, the light that LED is sent all enters light guide plate, has avoided light loss to greatest extent.

The emission characteristics that this structure need not reserved above light source module light compensates required space, directly carries out mixed light by the folding mixed light guide plate of spreading out, and has further reduced the thickness of LCD back light system.

Embodiment four

Embodiment five

Embodiment six

Consult Figure 11, substantially according to the structure identical with embodiment one, the bottom of reflective box that different is is opening not, and light source module is positioned on the base plane of reflective box, the top of light source module adds a dividing plate 4 in addition, have some apertures on this dividing plate, corresponding with the position of led light source on the aluminum base PCB.The ganoid reflecting surface of dividing plate reduces the loss of light reflection.The advantage of this structure is to reduce the leakage of light.

Embodiment seven

Substantially according to the structure identical with embodiment one, all there are lens (light uniforming device) that utilize the binary optical system principle top of different is each six-color element encapsulated LED light source in the light source module, design the optical texture of these lens according to actual needs, can obtain specific more uniform radiation pattern, follow-up optical design is simplified greatly.

More than be described in detail light source of the present invention and backing structure, obviously, those skilled in the art can do many improvement and conversion and not deviate from spiritual scope of the present invention.For example, can be rectangle with alteration of form, circle, ellipse etc.