The discription of led backlight
Jul 26, 2021
Backlight is an unfamiliar concept to most people. The so-called BackLight should be a light source behind the liquid crystal display (LCD), and its luminous effect will directly affect the visual effect of the LCD liquid crystal screen (LCM) . The liquid crystal display itself does not emit light. It displays graphics or characters as a result of its modulation of light. The development of the backlight can be traced back to the Second World War. At that time, ultra-small tungsten filament lamps were used as the backlight of aircraft instruments. This is the initial stage of the development of the backlight. After half a century of development, the backlight has now become an independent subject of electronics, and has gradually formed a research and development hotspot.
With the continuous development of liquid crystal display technology, the application fields of liquid crystal displays, especially color liquid crystal displays, are constantly expanding. Driven by the liquid crystal display market, the backlight industry is showing a booming scene.
The LCD is a non-luminous display device, which requires the use of a backlight to achieve the display function. The performance of the backlight source will directly affect the display quality of the LCD. The cost of the backlight source accounts for 3-5% of the LCD module, and the power consumed accounts for 75% of the module. It can be said to be a very important part of the LCD module. Components. High-definition, large-size LCDs must be matched with high-performance backlight technology. Therefore, as the LCD industry strives to open up new application areas, the high-performance backlight technology (such as high brightness, low cost, low power consumption) It also plays the role of behind-the-scenes heroes. The backlight is the light source that provides the LCD panel. It is mainly composed of light source, light guide plate, optical diaphragm, plastic frame, etc. The backlight has the characteristics of high brightness, long life and uniform light emission. Currently there are mainly EL,
There are three types of backlights, CCFL and LED, which are divided into side-light type and direct-light type (backlight type) according to the different light source distribution positions. As LCD modules continue to develop in the direction of being brighter, lighter, and thinner, edge-lit CCFL backlights have become the mainstream of current backlight development. The electroluminescence (EL) backlight body is thin and light, and provides uniform light. Its power consumption is very low, the required working voltage is 80～100Vac, the inverter that provides the working voltage can transform the input of 5/12/24Vdc into AC output. However, the EL backlight has a limited service life (the average service life is 3000-5000 hours under the condition of 50% brightness, and the service life will be greatly shortened at a higher brightness level). Therefore, the ideal inverter for EL back lighting The device allows the output voltage and frequency to increase with the aging of the EL bulb, thereby prolonging the effective life of the display using the EL back-illuminated light source.
EL back lighting is more suitable for small reflective LCD applications such as watches, digital desk clocks and monochrome PDAs that require extremely weak lighting for use in dim or dim light conditions. However, low efficiency, low brightness, and short lifetime make it unsuitable for transmissive back lighting applications such as large LCDs required for laptop computers and flat-panel desktop monitors.
The service life of LED backlight is longer than EL (more than 5000 hours), and it uses DC voltage. It is usually applied to small monochrome displays, such as telephones, remote controls, microwave ovens, air conditioners, instruments, stereo audio equipment, etc. However, its brightness is currently not enough to provide a back light source for large transmissive displays. The structure of LED backlight and CCFL backlight is basically the same. The main difference is that LED is a point light source, while CCFL is a line light source.
The small cold cathode fluorescent lamp (CCFL) provides the brightness and lifetime (and light control capability) required for large LCDs, which is why it is still the most commonly used method of backlighting to this day. However, heat accumulation is a concern.
The role of the light guide plate is to guide the light scattering direction to improve the brightness of the panel and ensure the uniformity of the panel brightness. The good quality of the light guide plate has a great influence on the backlight plate. Therefore, the design of the light guide plate in the edge-lit backlight plate Production is one of the key technologies. The light guide plate is made by using injection molding method to press propylene into a smooth surface
