Backlight Light Guide Plate's Classification
Dec 14, 2021
The backlight light guide plate currently mainly has three types of backlight sources: EL, CCFL and LED according to the type of light source. According to the different distribution positions of the light source, it is divided into side-light type and direct-light type (backlight type). The following is a brief introduction of them.
1. Edge light type. That is, the Suzhou backlight is made by setting the linear or point light source on the side of a specially designed light guide plate. According to the needs of actual use, it can be made into two-sided or even three-sided. Edge-light type backlights can generally be made very thin, but the light utilization rate of the light source is small, and the thinner the light source, the smaller the utilization rate, the maximum is about 50%. The core of its technology is the design and production of light guide plates. The most commonly used edge-light type are LED backlight and CCFL backlight. As LCD modules continue to develop in the direction of being brighter, lighter, and thinner, edge-lit CCFL-type backlights have become the mainstream of current backlight development.
1) LED backlight. LED lights are also called light-emitting diodes. Compared with other light sources, the power consumption of a single LED light is the smallest. From blue to red, LED lights come in many colors, and another special color is white. In various colors, it can be roughly divided into two types: high-brightness and low-brightness. Since white is a mixed color, there is no identifiable wavelength value. Therefore, the backlight light guide plate is represented by its coordinate value on the chromaticity diagram, and we customize it as "cool white" and "warm white". In various colors, there is a problem of color deviation. Among them, blue and white are more obvious, especially white. Now LED suppliers can't effectively control it.
2) CCFL backlight. The biggest advantage of this kind of backlight is its high brightness, so the larger black and white negative phase, blue mode negative phase and color liquid crystal display devices basically use it. In theory, it can make a variety of colors based on the color matching principle of the three primary colors. Its disadvantage is that it consumes a lot of power, it also needs inverter circuit drive, and the working temperature is narrow, between 0 and 60 degrees, and other backlight sources such as LED can reach between -20 and 70.
2. Backlight type at the bottom. It is a flat surface light source with a certain structure, the backlight light guide plate can be a continuous and uniform surface light source, such as EL or flat fluorescent lamp; it can also be composed of more point light sources, such as dot matrix LED or incandescent lamp Backlight, etc. Commonly used are LED dot matrix and EL backlight.
1) EL backlight. That is, electroluminescence is a cold light source that emits light by the intrinsic luminescence of phosphors excited by an alternating electric field. Its biggest advantage is its thinness, which can be 0.2~0.6mm in thickness. Disadvantages are low brightness, short life span (usually 3000~5000 hours), inverter drive is required, and flicker, noise and other defects may occur due to circuit interference. There are two types of EL drives: inverter and Driver IC. Because the frequency and load output voltage of the current Driver IC cannot reach the typical conditions of EL (400Hz, AC100V), the brightness is lower than that of the inverter drive. Recently, white light (full-color) EL and LCD backlights have emerged. However, due to the low brightness, it is basically used for small size liquid crystal displays below 4 inches. Such as: mobile phones, PDAs, game consoles, etc. Full-color (white light), large-size brightness backlight, and now the mainstream is still using CCFL as the light source.
2) LED bottom backlight. The advantages are good brightness and good uniformity. The disadvantage is that the thickness is large (greater than 4.0mm), the number of LEDs used is large, and the heating phenomenon is obvious. Generally, low-bright colors are used for design, while high-bright colors are basically not considered due to the high cost.
