CN201265818Y - LCD backlight system employing white LED light source - Google Patents

Abstract

The utility model provides an LCD backlight system using a white LED light source. In the white LED light source, a red LED chip and a blue LED chip are encapsulated inside the same device, and the white LED light source is covered by an embedding material containing fluorescent powder capable of generating green light by blue light to form an LED light source. The blue light given out by the blue LED chip in the LED light source passes through the embedding material containing fluorescent powder, part of the blue light is converted into green light and part of the blue light is still blue light, and red light, blue light and green light are mixed to form white light. The spectral component of the whole light source can be changed by configuring the number of the two chips and the concentration of the fluorescent powder or respectively adjusting the operation current of the LED chips. The emergent light of all the LED light sources faces to a light conducting plate to form an illuminating lattice parallel with the optical axis. In the direction of the emergent light of the LED light source, the light conducting plate and a series of optical membranes are arranged in sequence.

Description

A kind of LCD back light system that uses White LED light source

Technical field

The utility model relates to a kind of back light system that uses semiconductor light sources, be specifically related to use LED (Light-Emitting Diode, light emitting diode) LCD of light source (Liquid Crystal Display, liquid crystal display) back light particularly relates to the led light source of luminescent conversion and mixing.

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.

Another patent application of the inventor " a kind of LCD back light system that uses led light source ", application number is 20082009632.3, the applying date is on February 18th, 2008, this patent provides a kind of LCD back light system that uses the mixed color LED light source in conjunction with the 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 are mixed form mixed light, described red LED light source is that monochromatic red LED chip sends ruddiness.

In the existing patent, there is not back light system to use and adds the white LED light source of green emitting phosphor mutual encapsulation one-tenth as backlight, to improve the color representation power and the gamut range of display device by red, blue led chip.

Content

The purpose of this utility model is to provide a kind of LCD back light system that uses White LED light source.

Described White LED light source is to use red LED chip and blue-light LED chip mutual encapsulation in same device, and can be covered by the blue-light excited Embedding Material that goes out the fluorescent material of green glow with containing, and forms led light source.

The emission dominant wavelength ranges of described blue-light LED chip generally is 380nm～480nm; The emission dominant wavelength ranges of red LED chip generally is 580nm～700nm; The dominant wavelength ranges of the green light of being launched by blue-light excited fluorescent material generally is: 490nm～570nm.

Described fluorescent material mixes with Embedding Materials such as epoxy resin or silica gel in suitable ratio, covers led chip then.

By containing the Embedding Material of fluorescent material, part is transformed into green light to the blue light that blue-light LED chip in the led light source sends earlier, and part still is a blue light, and the mixed back of red, blue, green three coloured light forms white light, is transmitted into the outside of led light source.

About the proportioning of finished product, manufacturing and the fluorescent material of fluorescent material, to mix be prior art and technology, and Related product can be bought or customize.

In led light source, the ruddiness of dominant wavelength 580nm～700nm can not absorbed or conversion by above-mentioned fluorescent material.

In the described led light source, after the green light that blueness, red light and the fluorescent material that two kinds of led chips send excites is mixed, form white light.These three kinds of light components form complementary ideally in spectrum, can realize high color developing under high light efficiency.

The chromaticity coordinates of lcd screen (white point) depends on the ratio of several color of light of light source in the LCD back light system.In the light component of led light source, the shared ratio of versicolor light is decided according to the demonstration needs of screen color.Can perhaps change the luminosity of two kinds of chips by the quantity of two kinds of chips of configuration and the concentration of fluorescent material, to change the spectral component of whole light source by the operating current of regulating led chip respectively.In the led light source of back light system, ruddiness generally occupies greater than one of percentage ratio in total light intensity or total light flux, specifically according to using needs to decide, accounts for 5%～20% as ruddiness, or 30%～40%, or other arbitrary proportions.

As shown in Figure 3, Figure 4, in described back light system, go up installation a plurality of White LED light sources (1) at printed substrate (PCB) (2), 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 White LED light source 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 each chip of led light source 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, the selection of led chip in the led light source (comprising operating current, luminosity, dominant wavelength etc.) is according to using needs to decide, 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, the peak value that red, blue, green three colors are arranged in the composition of the emission spectrum of led light source, can improve the gamut range of display device, near or reach the level of the back light system that uses the RGB three primary colors LED light source; 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 in conjunction with the embodiments with reference to the accompanying drawings.

Description of drawings

Fig. 1 and Fig. 2 are respectively the profile and the structural representations of White LED light source in the utility model;

Fig. 3 is the generalized section of the utility model LCD back light system;

Fig. 4 is the vertical view that the PCB of led light source has been installed in the utility model LCD back light system.

The specific embodiment

Embodiment one

See also Fig. 1 and Fig. 2, White LED light source (1) comprises two led chips: red LED chip (11) and blue-light LED chip (12), and: Embedding Material silica gel (13) and be blended in fluorescent material (14) in the Embedding Material.The Embedding Material that contains fluorescent material covers two led chips.Led light source (1) also comprises shell (15), lead essential encapsulating materials such as (16).This led light source has the lead-in wire that connects the outside, and two kinds of led chips can independently be controlled to adjust.

In the present embodiment, the dominant wavelength of red LED chip is selected 615nm～625nm, and the dominant wavelength of blue-light LED chip is selected 450nm～455nm, fluorescent material by the dominant wavelength of blue-light excited green light of launching at 555nm～565nm.

See also Fig. 3 and Fig. 4, a plurality of White LED light sources (1) are installed on the PCB (2), and led light source is evenly distributed.In the light component of this backlight, ruddiness accounts for 5%～20% of total light intensity or total light flux.

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 red LED chip and blue-light LED chip is 150mA, the high-power and high-luminance LED chip of power 0.5W.

PCB has made corresponding circuit on (2), makes the led light source can operate as normal and control the led chip of two kinds of colors respectively.

As shown in Figure 3, 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 White LED light source 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 three

Basic identical with embodiment one, different is that middle red LED chip (11) of led light source (1) and the equal selection work electric current of blue-light LED chip (12) are the low-power LED chip of 20mA, and led light source compares 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.

Claims (5)

1. LCD back light system that uses White LED light source, it is characterized in that described White LED light source is to use red LED chip and blue-light LED chip mutual encapsulation in same device, and can cover by the blue-light excited Embedding Material that goes out the fluorescent material of green glow with containing, form led light source.

2. according to the back light system of claim 1, it is characterized in that the emission dominant wavelength ranges of blue-light LED chip in the described led light source is 380nm～480nm; The emission dominant wavelength ranges of red LED chip is 580nm～700nm; The dominant wavelength ranges of the green light of being launched by blue-light excited fluorescent material is: 490nm～570nm.

3. according to the led light source of claim 2, it is characterized in that described fluorescent material mixes with Embedding Material, covers led chip then.

4. according to the back light system of claim 1, it is characterized in that a plurality of White LED light sources are installed on printed substrate, the light direction of all led light sources forms a luminous dot matrix that optical axis direction is parallel to each other in the face of LGP.

5. according to the back light system of claim 1, it is characterized in that light direction, be arranged in order LGP and a series of blooming at led light source.

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