A kind of LCD back light system that uses led light source
Technical field
The utility model relates to a kind of back light system that uses semiconductor light sources, is specifically related to use LCD (Liquid Crystal Display, the liquid crystal display) back light of LED (Light-Emitting Diode, light emitting diode) light source.
Background technology
Along with the technology of ultra-bright LED is ripe gradually, price constantly descends, because of its have life-span length, vibration resistance, luminous efficiency height, noiseless, be not afraid of advantages such as low temperature, no mercury pollution problem and cost performance height, LED has obtained very big expansion in various signals demonstrations and lighting source Application for Field, especially in the application facet of backlight of LCD, it replaces CCFL (Cold-CathodeFlorescent Lamps gradually, cold cathode fluorescent tube) backlight 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.
As backlight, LED can roughly be divided three classes: white, monochrome and polychrome.When using White LED backlight, circuit is simple relatively, and 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, and white colour temperature is fixed, and colour gamut is less.When constituting white with red, green, blue LED, can improve LCD display preceding color and brightness characteristics, when enlarging colour gamut, can also realize high brightness, thereby more superior than CCFL in this respect.Use the RGB of monochromatic LED backlight, 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 angle of departure.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, but the back light system of this scheme drives and the control circuit more complicated.
In order further to enlarge color expression range, be not limited to R (red) in the past, green (G), B (indigo plant) three primary colors, can realize multicolor by appending new color, make lcd screen have broader colour gamut.
Because LED is a spot light, radiation pattern is conical, so the key of LED-backlit is to obtain a surface of evenly illuminating.LGP is the effective ways that improve color homogeneity.In order to obtain high brightness, be better than using the scheme in sidelight source with LED scheme of direct illumination after lcd screen.
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.
In the back light system of existing patent, all do not mention light source mixing monochromatic LED light source that blue led adds green emitting phosphor as backlight, to improve the color representation power and the gamut range of display device.
Content
The purpose of this utility model is to provide a kind of LCD back light system that uses the mixed color LED light source in conjunction with the red LED light source.Back light system of the present utility model uses two kinds of led light sources: mixed color LED light source and red LED light source.
Described mixed color LED light source is to excite green emitting phosphor to send green glow by blue-light LED chip, indigo plant, green glow is mixed form mixed light.
Described red LED light source is that monochromatic red LED chip sends ruddiness.
The above-mentioned employed fluorescent material of mixed color LED light source comprises green emitting phosphor, thus in the composition of its emission spectrum indigo plant is arranged, the peak value of yellow two colors, the White LED light source that forms than common colour mixture has increased the green spectral composition.About the proportioning of finished product, manufacturing and the fluorescent material of the fluorescent material of green, to mix be prior art and technology, and Related product can be bought or customize.
The chromaticity coordinates of lcd screen (white point) depends on the ratio of several color of light, needs according to display screen, the optional scope of the colour temperature of mixed color LED light source generally is: 3500K~9000K, wherein the optional scope of the dominant wavelength of blue-light LED chip generally is: 440nm~480nm, and the optional scope of the peak wavelength of the green light that excites generally is: 490nm~540nm; The optional scope of the dominant wavelength of red LED light source generally is: 580nm~635nm.
As shown in Figure 1 and Figure 2, in described back light system, a plurality of mixed color LED light sources (11) and a plurality of red LED light source (12) are installed simultaneously on printed substrate (PCB) (2), two kinds of led light sources are intermeshing evenly distributed.The light direction of all led light sources is in the face of LGP, according to certain rules, a determining deviation arranges, and forms a luminous dot matrix that optical axis direction is parallel to each other.
At the light direction of led light source, be arranged in order LGP (3) and a series of blooming (4).
During work, the light that mixed color LED light source and red LED light source are sent all enters LGP (3), through fully reflection mixing, again by blooming devices such as (4), shines the rear surface of liquid crystal panel, forms back lighting.
In said structure, certain rule that described led light source is arranged and spacing do not have strict restriction, are evenly to be distributed as final goal with the brightness on the LCD screen, color.
Can regulate the brightness of two kinds of led light sources in the described back light system respectively,, obtain suitable screen color to change the spectral component of whole light source.
The selection of led light source is according to using needs to decide in the back light system, and the encapsulating structure of led light source (comprising electrical structure, optical texture, frame for movement) is also determined according to different designs and use needs.
The beneficial effects of the utility model are: ordinary white led light source spectral component only concentrates on indigo plant, yellow dichromatism, scheme of the present utility model remedies the spectral component of the led light source of back light system and improves, increase composition green, ruddiness, can improve the gamut range of display device; And the back light system drive circuit complexity of RGB three primary colors LED light source, the shortcoming that cost is high have been avoided using.
Be described in further detail the utility model with reference to the accompanying drawings in conjunction with the embodiments.
Description of drawings
Fig. 1 is the generalized section of the utility model LCD back light system;
Fig. 2 is the vertical view that the PCB of two cover light sources has been installed in the utility model LCD back light system;
The specific embodiment
Embodiment one
See also Fig. 1 and Fig. 2, a plurality of mixed color LED light sources (11) and a plurality of red LED light source (12) are installed on the PCB (2) simultaneously, and two kinds of led light sources are intermeshing evenly distributed respectively.Because in the light component of backlight, ruddiness generally accounts for 5%~20% of total light intensity or total light flux, so mixed color LED light source (11) quantity is more, red LED light source (12) negligible amounts.
Wherein the colour temperature of mixed color LED light source is selected 6500K~7500K, and the dominant wavelength of red LED light source is selected 615nm~625nm.
Led light source adopts paster that the form of (SMT) is installed, and the shooting angle of light (FWMH) is 120 °.The equal selection work electric current of used mixed color LED light source and red LED light source is 150mA, the high-power and high-luminance LED of power 0.5W.
PCB has made corresponding circuit on (2), and two kinds of led light sources can operate as normal also be controlled respectively.
As shown in Figure 1, at the light direction of led light source, be arranged in order LGP (3) and a series of blooming (4).
During work, the light that mixed color LED light source and red LED light source are sent all enters LGP (3), and through fully reflection mixing, by blooming (4), its effect is that the direction of light is put in order again.Last light shines the rear surface of liquid crystal panel, forms back lighting.
Embodiment two
Basic identical with embodiment one, different is that wherein mixed color LED light source (11) selection work electric current is 150mA, the high-power and high-luminance LED of power 0.5W, and red LED light source (12) selection work electric current is the low-power LED of 20mA, compares intensive arrangement.
Embodiment three
Basic identical with embodiment one, different is wherein mixed color LED light source (11) and the equal selection work electric current of red LED light source (12) be the low-power LED of 20mA, compare intensive arrangement.
More than be that preferred implementation of the present utility model is described, those skilled in the art is in the scheme scope of the utility model technology, and common variation and the replacement carried out all should be included in the protection domain of the present utility model.