Perché lo schermo LCD che vediamo è nero?

La figura seguente è il diagramma schematico di base dello schermo LCD. Spiegherò brevemente il processo e poi spiegherò.

Look from the bottom up. The backlight is a point light source that emits a kind of light that is directed to "all directions" through the light guide plate, and the backlight becomes uniform. The light from "all directions" passes through the polarizer and is filtered. those that cannot pass through. The liquid crystal material is optically active, and can rotate the "horizontal" light slowly when it is rotated to 90 degree , 270 degree , etc., and can be completely changed to "vertical", and then pass through the filter plate (this TN type liquid crystal matching method filter plate and When the polarizing plate is 90 degree ), its brightness is 100 percent ; when it is rotated to 180 degree , 360 degree , etc., it will completely fail to pass through the filter, and its brightness is 0 percent ; the rest of the angle grayscale is between 0-100 percent .

In questo momento, ci sono solo colori di luminosità tra il nero e il bianco, quindi ogni gruppo di 3 cristalli liquidi passa attraverso il vetro del filtro di colore rosso, verde e blu rispettivamente per formare un gruppo di 3 cristalli liquidi di tre colori primari, 3 colori (il la cui proporzione è determinata dall'angolo di rotazione dei cristalli liquidi). decisione) sovrapposti a un colore desiderato, un tale gruppo di cristalli liquidi, diventa un pixel.

Se lo vedi e lo capisci, le seguenti conclusioni saranno facili da capire. Allora, perché la maggior parte degli schermi LCD in bianco e nero che vediamo escono neri?

    Mainly for reasons of cost, necessity and longevity. There is no need to use color, and the cost of color filter glass can be saved. There is no need to combine three primary colors into one. For the same panel, the pixels are tripled. Only black and white can be used, not black{{0}}white uniform grayscale. It can reduce the cost of the control circuit (only 0 and 1 are needed = =) The voltage control can also be very arbitrary, it does not need to be very black or very white, it is almost enough, the accuracy of the circuit design is reduced a lot, many circuits and components are used more Less, the higher the life and stability, and the lower the cost. For products that do not have a backlight and use ambient light as the light source, the backlight is also omitted, and the power and energy consumption of the backlight is also omitted. Why not use the background black For the question of displaying white, the answer is that commonly used display panels such as glass and plastic are transparent, and the cost of dyeing glass and plastic black will increase. The display method used by the LCD is based on the principle described above. When the power is off, the liquid crystal does not rotate, the backlight is not turned on, the upper and lower polarizers are perpendicular to each other, and all the light is blocked, so it is black.