Working Principle of TFT LCD

- Mar 19, 2018-

               

                 It is known that the working principle of crt is that the filament is heated after being energized and the cathode is excited to emit an electron current. The electron current is accelerated by the inner metal layer with a high voltage, and the lens is focused to form a very fine electron beam and hit on the fluorescent screen. Make the phosphor glow. And crt principle is completely different, lcd needs from the back of the light source, when the light beam through the layer of liquid crystal, the liquid crystal will be side by side or an irregular twist shape, so the LCD is more like a gate, select the light penetration or not, we can See different shades of picture on the screen.

                At present, the mainstream liquid crystal display is a thin film transistor lcd (tftlcd), which is an extension of the original liquid crystal display technology. Tft liquid crystal has a semiconductor switch for each pixel, so as to completely control a single pixel, the liquid crystal material is sandwiched between the tft glass layer and the color filter layer, and the voltage of the liquid crystal can be changed by changing the voltage value of the liquid crystal. Controls the last light intensity and color that appears.

               The liquid crystal is generally transparent unless voltage is applied. After pressurization, part of it changes and becomes opaque. This conversion speed of liquid crystal is usually very slow (more on this later). In 1992, emi announced the invention of a new liquid crystal display technology ferroelectric liquid crystal flcd (ferroelectriclcds). The advantage of ferroelectric liquid crystals is fast response, up to microseconds. And without changing the voltage can maintain the current state, which is more power, which is very meaningful for laptops, pda and other portable devices. There are many advantages of flcd, but there are few products on the market. Because flcd is very sensitive to vibration, it is very easy to damage the crystal, but it will certainly improve in the future.

               Although the future of ferroelectric liquid crystal flcd is still unknown, it also has the advantages of high contrast and large viewing angle, which will cause a certain impact on mainstream tft in the market.

               At normal operating temperatures, flcd's response time is only 70us! This short time is almost negligible.