Why do black spots or bright spots appear on TFT LCD screens?

Palm-sized DVDs, portable color TVs and laptop computers mostly use true-color TFT LCD screens to display images. Its bright and lifelike colors, thin, lightweight and portable size, soft light, no radiation and no eye damage are all very popular among consumers. However, careful users sometimes find that on the TFT LCD display, there are individual black dots in the white image, and individual white dots (including red, green and other color dots) in the black image. This makes people suspect that the machine or display is defective or defective. In fact, this is a very common phenomenon of active matrix TFT LCD screens. It does not mean that the machine or the display screen is faulty, nor does it mean that they are defective products. This phenomenon also exists whether it is a domestic machine or an imported brand-name machine.

To display large-format, detailed color images on a TFT LCD screen, the entire display screen needs to have hundreds of thousands of pixels. Take the palm-sized DVD player XD?DW1 produced by Japan's AIWA Company, a world-famous manufacturer, as an example. It uses a 5.8-inch TFT color LCD display to display images, with a pixel count of 1200 (X) × 234 (Y). =280800 (280,000 pixels). As long as one of the 280,000 TFT tubes is open-circuited, the pixel will turn into a black dot; if there is a short-circuit, the pixel will turn into a white dot (or red, blue, etc. color dot). For these 280,000 TFT tubes (and the same number of liquid crystal devices), none of them are broken. At the current level of process technology, no TFT liquid crystal production plant in the world can achieve this. Of course, among a large number of TFT LCD displays, there will be very few devices without a single broken TFT tube. However, the price of the LCD screen obtained by "selecting one out of a hundred" is simply unacceptable to ordinary consumers. Therefore, all TFT LCD display manufacturers around the world, including the world-famous Japanese companies such as Toshiba, Panasonic, Hitachi, Sharp, etc., generally stipulate a reasonable allowable black spot on the LCD screen without affecting the image quality and viewing effect. , the number of bright spots, as the quality inspection standard.

To avoid consumers' doubts, some complete machine manufacturers specifically explain this in the product manual. For example, Japan's Aihua Company has this explanatory text in the manual of its XDDW1 DVD player:

A few bright white or dark spots may appear on the LCD screen. This is a very common phenomenon in active-matrix display technology and does not indicate a malfunction or defect.

For various DVDs, color TVs and computers that use the most advanced and mature active matrix TFT LCD screens, a few bright spots or black spots appear on the LCD screen. As long as they are within the scope of the LCD screen quality regulations, It will not affect the image quality and viewing effect, nor does it mean that the machine or display is faulty or defective. Of course, if there are more black spots or bright spots than specified in the display acceptance standards, thus affecting the image quality and viewing effect, consumers should negotiate with the relevant manufacturers to protect their due rights.