LED LCD TV light source technology and the advantages of DLP

This white paper will explore the light emitting diode (Light Emitting Diode; LED) technology and its application to the influence caused by the TV products. This paper will focus on the application of the technology advantages and challenges, and its application to the special advantages of DLP products.

introduce

LED has become a key to the extensive use of lighting technology. Since its invention, LED has been used in a variety of common products, including watches, calculators, remote control, lights, and household equipment. With the rapid development of LED technology, with the continuous improvement of brightness and efficiency, new applications are emerging.

LED history

Since the early twentieth Century, scientists are constantly looking for ways to light material. In 1907, Henry Joseph Jand discovered that silicon carbide (SiC) can emit light. Over the next 50 years, scientists have discovered that light emitting compounds. By the 1950s, with the continuous deepening of the study of gallium arsenide (GaAs), the discovery of LED has finally come true.

Baer laboratory, HP, Meng Shandou and RCA IBM, the company first started LED research in 1960s. HP and Monsanto first launched a commercial red light based on gallium arsenide LED in 1968. In the early 70s, with TI, HP and Sinclair and other companies to launch new products such as calculators and electronic watches, LED applications surge. Other applications such as indicators and alphanumeric displays will soon become the mainstream application of LED, and continues to date.

The background of LED technology as the name implies, LED is the luminous diode. Diode is the most basic semiconductor components, its role is to control a certain range of conductivity. The simplest diode is made up of a poor conductor of electricity and modified (doped) to increase the free electrons. A high electron content material (called N) is connected with a low electron content material (called P), which provides a pathway for free electron flow. This connection is called a PN connection. LED is a semiconductor diode with PN connections, after the release of photons. This process is called the injection of light, which occurs in the process of filling the low energy hole from the N material to the P type material. When high energy electrons enter a low energy hole, they release energy and produce photons. The materials used in the P and N type material layers, and the spacing between the two, determine the wavelength and energy levels of the light. There are many kinds of materials which can be used to produce LED, which is widely used in the fields of gallium arsenide (AlGaAs), AlInGaP (indium gallium phosphide) and indium gallium nitride (InGaN). Indium gallium phosphide is commonly used to produce red and yellow light, while indium gallium nitride is commonly used to produce blue and green light - these materials are generated within the visible light spectrum. Combined with the new production structure, they can be made into a very bright LED for general lighting and automotive lighting. Some additional application architecture began to generate phosphide white, with low energy consumption and longer life and the ordinary incandescent lamp and fluorescent lamp to compete. Global LED production has reached about 4 billion per month, the major manufacturers concentrated in Taiwan, Japan and the United States, while the Taiwan region accounted for the world's total output of the share of the top 50%. Most manufacturers are only LED grain packaging, only a few have the ability to actually produce LED grain. Figure 1 depicts the share of the LED market in both low and high brightness LED.

3 LED technology innovation and breakthrough recently grain materials packaging production of LED reached a high level of brightness. The substrate uses a new material that improves the thermal conductivity, thereby absorbing more energy and emitting a brighter light. The brightness boost brings new LED applications, such as automotive lighting, traffic signals, and the latest TV display. Figure 2 illustrates the new architecture. The significant improvement in the level of production of aluminum indium gallium phosphide and indium gallium nitride, the brightness of the blue and green light was improved, while other colors (such as amber and cyan) also came out. These improvements enable the system to faithfully reproduce the color, which is equivalent to the brightness of the ordinary bulb technology, and has a longer lifetime. Other performance improvements include the characteristics of the system layer, such as instantaneous imaging, no mercury, no color refresh artifacts, dynamic adjustable brightness, and wider color gamut. Figure 3 compares the gamut of LED and general reference standards (Rec. 709). The color gamut of LED lighting is very wide (more than 40% of the color standard of HDTV), so the color fidelity is higher. LED technology is especially attractive for TV products that have high requirements for life and color reproduction. With the continuous development of LED technology, its impact on the television industry is also growing. Figure 4 describes the evolution of LED technology and the luminance efficiency of the next few years.

4 LED LED control technology challenges grain thermal stability is the key to LED hairvortex optical properties and stability of the. The diffuse light emitted by the LED architecture ranges from the surface of the PN structure and the surrounding area in all directions (evenly distributed in 180 degrees). Although this seems to be highly efficient, most of the light is absorbed by neighboring grains, substrates, or other LED surfaces. This absorption results in an increase in the heat load of the LED device. In order to obtain maximum light output and reliability, thermal issues must be properly addressed. In addition, for applications that require the use of light energy to focus on small display devices such as DLP HD TV, any light beyond the system's optical path angle is not available, and there may be heat and increase system energy