What is a color filter (CF)?

Color filter (CF)

If you use a magnifying glass to observe the LCD panel, you will find that it looks like the following figure. We know that red, blue and green are the so-called three primary colors. That is to say, using these three colors, we can mix various colors. Many flat-panel displays use this principle to display colors. We divide the three colors of RGB into three independent points, each with different grayscale changes, and then use the three adjacent RGB display points as a basic unit of display, that is, pixel. Then this pixel can have different color changes. Then for a display screen that requires a resolution of 1024*768, we only need to make the composition of this flat-panel display have 1024*768 pixels to correctly display this screen. In the figure, the black part between each RGB point is called Blackmatrix. It is mainly used to cover the part that is not intended to be transparent. For example, some ITO wiring, or Cr/Al wiring, or TFT part. Therefore, we can see in the picture that each RGB bright spot is not a rectangle, and there is a part covered by the black matrix in its upper left corner. This black missing part is the location of the TFT.

The following figure shows the common arrangement of color filters. Stripe arrangement is most commonly used in OA products, that is, our common notebook computers, desktop computers, etc. Why is this application using stripe arrangement? The reason is that most of the current software is a window interface. In other words, the screen content we see is composed of a lot of boxes of different sizes. The stripe arrangement can make the edges of these boxes look straighter, and there will be no straight line, which will look rough or jagged. But if it is applied to AV products, it is different. Because TV signals are mostly people, the lines of people are not straight, and most of their contours are irregular curves. Therefore, in the beginning, mosaic arrangement (mosaic, or diagonal arrangement) was used for AV products. However, most recent AV products have been improved to use triangle arrangement (triangle, or delta arrangement). In addition to the above arrangement, there is another arrangement called square arrangement. The difference between it and the previous ones is that it does not use three points as a pixel, but four points as a pixel. The four points combined just form a square.