The role of LED backlight on LCD
May 07, 2018
The backlight is an important component in the LCD structure. Most of LCD products are transmissive. The backlight of a transmissive LCD product is an integral part of the LCD.
Cold cathode fluorescent lamps (CCFLs) currently occupy a leading position in LCD backlights. LEDs have the advantages of wide color gamut, white point adjustment, high dimming rate, and long life. Therefore, they have recently been developed as new types of LCD backlights, such as Desktop LCD monitors and LCD TV applications.
The LED backlight for LCD (hereinafter abbreviated as LED backlight) is a new type of backlight technology, and there are many kinds of backlight sources, but it is not as common in LCD products as there are technical problems and cost issues. Some of the more practical LED backlights. Static lighting LCD backlights can improve light efficiency, and are an important way to increase the ratio of the output light of the screen to the light output of the light source and improve the backlight of the LCD. Static lighting LCD backlight is one of the methods. The principle is to make each sub-pixel of the LCD illuminate with the corresponding color element, thus eliminating the color filter and improving the light efficiency.
In an LCD with a static illumination backlight, a micro lens array is mounted at the bottom of the pixel layer so that each pixel bottom corresponds to a suitable micro lens. The backlight illumination system used here is a three-primary direct-view backlight source. Each color light source is imaged on its corresponding sub-pixel and the well is projected on the display screen through a projection lens.
In order to provide sufficient brightness on the display screen and improve the uniformity of the display: In this LCD device, a light refractive element and a total internal reflector (TIR) wedge light guide plate are used, and a suitable refractive layer is provided in the light guide plate.
Static lighting backlights typically use three green, blue and blue CCFLs. In recent years, research and development of static backlighting LCDs have used LEDs as their backlight.
Static lighting LCD backlight characteristics
In static backlight LCD devices, the light distribution angle output by the TIR wedge light guide is between 70° and 90°. The use of this backlight eliminates the loss of light due to the color filter layer (avoiding the color filter layer), and allows the device to achieve three times the transmittance of conventional LCDs. This kind of backlight can also simplify the device structure and reduce power consumption.
In order to further reduce the light loss of the light source and improve the light distribution angle to eliminate the environmental pollution caused by the use of mercury, replacing the CCFL as the backlight of the device has become the development trend of the static lighting LCD backlight. Currently, LED static illumination backlights have been successfully used in 33-cm diagonal XGA resolution LCD devices. Can reduce power loss, suitable for high brightness product applications.
The feedback LED backlight uses red green blue LED as the LCD backlight to obtain better color quality, reduce power consumption, to avoid the use of mercury caused by environmental pollution, the need to control the color temperature of white light, to achieve a long enough life.
