Today, display technology is evolving toward high definition, low electromagnetic radiation, low power consumption, and small size. Although the production technology of CRT (Cathode Ray Tube) displays has become more and more mature and the display quality of images has become better and better, its volume and radiation problems are still unavoidable by its own physical characteristics. Therefore, the LCD display is accelerating the pace of replacing the traditional CRT display with its small size, light weight, and no radiation, and is also hailed by many as the terminator of the CRT. Let's talk about the working principle of LCD display.
The most important substance in liquid crystal displays is liquid crystal. It is a regularly arranged organic compound and is a substance between a solid and a liquid. Currently used is a molecular arrangement that is most suitable for the manufacture of liquid crystal displays. Thin column type liquid crystal. The physical properties of liquid crystals are: When the electricity is turned on, the order of the molecules becomes orderly, allowing the light to pass easily; when the electricity is not applied, the arrangement of the molecules is disordered and the light is prevented from passing. Let the liquid crystal molecules block or allow light to penetrate. Most of the liquid crystals are organic compound materials and consist of rod-shaped molecules. In the natural state, the major axes of these rod-shaped molecules are approximately parallel. The liquid crystal is poured into a well-manufactured grooved plane, and the liquid crystal molecules are arranged along the groove, so if the grooves are very parallel, the molecules will be completely parallel. In technical terms, the LCD panel contains two very delicate sodium-free glass materials, called Substrates, with a layer of liquid crystal sandwiched between them. When the light beam passes through this layer of liquid crystal, the liquid crystal itself stands or twists irregularly so as to block or smoothly pass the light beam.
From the perspective of the liquid crystal display structure, whether it is a laptop or a desktop system, the LCD display used is a hierarchical structure composed of different parts. The LCD consists of two glass plates, approximately 1 mm thick, separated by a uniform spacing of 5 μm containing liquid crystal material. Because the liquid crystal material itself does not emit light, there is a lamp as a light source on both sides of the display screen, and on the back of the liquid crystal display there is a backlight (or even light plate) and a reflective film, which is composed of fluorescent substances. Light can be emitted, and its main function is to provide a uniform background light source. The light from the backlight enters the liquid crystal layer containing tens of thousands of liquid crystal droplets after passing through the first layer of polarization filter layers. Liquid droplets in the liquid crystal layer are all contained in a fine cell structure, and one or more cells constitute a pixel on the screen. Between the glass plate and the liquid crystal material is a transparent electrode, the electrodes are divided into rows and columns, at the intersection of the rows and columns, by changing the voltage and changing the optical state of the liquid crystal, the liquid crystal material acts like a small light valve. Around the liquid crystal material are the control circuit portion and the driver circuit portion. When the electrodes in the LCD generate an electric field, the liquid crystal molecules are distorted, so that the light passing through them is refracted regularly, and then filtered through the second filter layer and displayed on the screen.
Liquid crystal display technology also has weaknesses and technical bottlenecks. Compared with CRT monitors, there are obvious differences in brightness, screen uniformity, viewing angle, and reaction time. The reaction time and the viewing angle depend on the quality of the LCD panel. The uniformity of the screen and the auxiliary optical module are greatly related. The brightness of the LCD monitor mainly depends on the backlight source.
For liquid crystal displays, the brightness is often related to his backplane light source. The brighter the backplane light source, the brightness of the entire LCD monitor will increase. In the early days of liquid crystal displays, because only two cold light tubes were used, uneven brightness and the like were often caused, and the brightness was not satisfactory. Until the introduction of four cold light tube products, there was no small improvement.
The signal response time is also the response delay of the liquid crystal cell of the liquid crystal display. Actually refers to the time required for the liquid crystal cell to change from a molecular arrangement state to another state of molecular arrangement. The smaller the response time, the better. It reflects the response speed of each pixel of the liquid crystal display to the input signal, that is, Pixel from dark to light or from bright to dark speed. The smaller the response time is, the user does not have the feeling of tail drag when watching the motion picture. Some manufacturers will achieve rapid response by reducing the concentration of conductive ions in the liquid crystal body, but the color saturation, brightness and contrast will be reduced accordingly, and even cause color cast. This signal reaction time went up, but at the expense of the LCD display. Some manufacturers such as "pure community" use a chip in the display circuit to add an IC image output control chip, dedicated to display signal processing method to achieve. The IC chip can adjust the signal response time according to the VGA output graphics signal frequency. Since there is no change in the physical properties of the liquid crystal, there is no effect on its brightness, contrast, or color saturation, and the manufacturing cost of this method is relatively high.
As can be seen from the above, the quality of the LCD panel does not fully represent the quality of the LCD monitor, and there is no excellent display circuit with no matter how good the panel is. It is believed that with the increase in the output of LCD products, the cost reduction, and the widespread popularity of LCD products, it is expected to be just around the corner.