Professionals in the display industry may know that LCD panels have grades, which can be divided into three grades: A, B, and C according to the quality. The basis for distinguishing the grades is the number of dead pixels. However, there are no hard and fast rules in the world, so the scoring standards vary from country to country.
1. What is a bad pixel?
As for the dead pixels, the liquid crystal display technology has developed so far, but it still cannot fundamentally overcome this defect. Because the LCD panel consists of two glass plates, the sandwich in the middle is a drop of crystals about 5 microns thick. These crystal droplets are evenly separated and contained in tiny cells, three of which make up a pixel on the screen. Under the magnifying glass, the pixels are square, and each pixel is a light-emitting point. Each light-emitting point has an independent transistor to control its current. If the transistor that controls the dot fails, the light dot will keep on or off. This is the bright spot or dark spot mentioned above, collectively referred to as the "dead spot"!
2. Judgment of Class A and Class B LCD screens
In the liquid crystal panel, the number of defective points within 5 is Class A, the number of defective points greater than 5 but less than 10 is Class B, and the number of defective points greater than 10 is Class C panel. Type A panels are common liquid crystal displays on the market, but Type B panels are bound to be produced in the production process of LCD panels, so most of these Type B panels will be digested by display manufacturers of inferior brands. C-class panels are completely unsuitable for display, and most of them are cut into small-sized qualified LCD screens for other fields. However, very few LCD manufacturers use C-class panels. Two or three years ago, there was a turmoil in which low-priced and low-quality LCD monitors disrupted the market.
Of course, the performance of Class B and Class C panels is incomparable to Class A panels except for the number of dead pixels. Compared with A-level panels, B-level panels and C-level panels have relatively uneven brightness, relatively insufficient color saturation, poor image color reproduction, and even damaged appearance. In addition to judging LCD panels with professional instruments, consumers can also visually distinguish them with the naked eye. Leveraging known A-level panels for comparison, B- and C-level panels immediately show their original shape. In addition, panel manufacturers also divide A-level panels into three steps: A, A, and A. Good-quality LCD panels are suitable for consumers who have higher display quality requirements. Under normal circumstances, the number of dark spots and bright spots on the A-class panel is less than 3, and the sum of bright spots and dead spots is less than 5; the number of dark spots on the A-class panel is less than 3, and the entire LCD screen has no bright spots, but the number of dead spots is less than 3; Class A panels have neither bright spots nor dark spots, and the number of dead spots is 0. A few LCD manufacturers claim that their LCD products have no bright spots, and their LCDs use A-level panels.
Now, more and more LCD screens will be used in vehicle-mounted instruments, including measuring instruments, automotive instruments, power instruments, etc. Then most of the LCD screens corresponding to these instruments are Class A LCD screens, and the use conditions are more stringent and harsh.
The working environment of industrial instruments is mostly harsh, and the reliability requirements for the LCD screen of the instrument are also relatively strict. General LCD screens cannot withstand such intensive work, including high and low temperature, drop, dustproof and waterproof effects, and cannot meet the requirements of industrial-grade instrument LCD screens. Therefore, an industrial-grade A-level LCD display must be selected.
Secondly, the instrument LCD screen selects low power consumption:
There are many circuits in a normal LCD screen. When these circuits drive the CRT to work, it needs to consume a lot of power, and as the volume increases, the power consumed by its internal circuits will also increase. In contrast, the power consumption of the liquid crystal display is mainly consumed on its internal electrodes and driving IC, so the power consumption is much smaller than that of traditional displays.
How to judge the grade of LCD panel in the market?
2022 02/21