Drivers and controllers

Drivers and controllers

YD is the frame synchronization signal, LP is the row synchronization signal, DATA is the column-driven data bus, used to transmit the output data (0 or 1) on the column, XCLK is the shift clock, and data is transmitted on DATA every time it changes. , DOFF# is to turn off the output signal. Taking a 640x480 monochrome screen as an example, 640 columns are output, corresponding to 640 bits of output, that is, 80 bytes, that is, each row scans, and the data required on the column is 80 bytes. Assuming that the column driver uses an 8-bit data line, 80 XCLK clocks are required for 80 bytes. These signals are all driven by the controller. Taking a 640x480 monochrome display as an example, the driver is an 8-bit bus. At the beginning of each frame, the controller continuously outputs 80 XCLKs and outputs the data of the first row. The column controller The data is latched at each XCLK, and then the controller outputs a pulse on YD, the row driver is reset, ready to output from the first row, the controller outputs a pulse on LP, the column driver is reset, and the data that has just been latched At the same time, the line driver also outputs from the first line, so the first line is displayed, then the controller outputs the second line of data, and then outputs an LP, so the second line is displayed, and so on, until the 480th After the line, output a YD and return to the first line, that is, the scan of the second frame is started.

It can be seen that the output of the driver is completely determined by the timing and data of the controller. For a system where the controller and the driver are separated, the driver cannot know the current display characteristics, such as monochrome or grayscale or color, what is the color depth, etc., so on such a system, grayscale/color can only use FRC Therefore, the operating frequency of a single general-purpose controller is quite high. It can reach dozens of megabytes, and even hundreds of megabytes for large sizes like computer displays.

Comparison of LCD monitor and traditional monitor

High display quality: Since every point of the LCD monitor keeps that color and brightness after receiving the signal, it emits constant light, unlike the cathode ray tube display (CRT) that needs to constantly refresh the bright spot. Therefore, the LCD display has high image quality and will never flicker, minimizing eye strain.

No electromagnetic radiation: The display material of the traditional display is phosphor, which is displayed by the electron beam hitting the phosphor. The electron beam will generate strong electromagnetic radiation when it hits the phosphor. Although there are many display products currently dealing with radiation problems A more effective treatment was carried out on the site to minimize the amount of radiation as much as possible, but it is difficult to completely eliminate it. Relatively speaking, liquid crystal displays have inherent advantages in preventing radiation, because there is no radiation at all.

Large viewing area: For displays of the same size, the viewing area of liquid crystal displays is larger. The viewing area of a liquid crystal display is the same as its diagonal size. In the case of cathode ray tube displays, the front panel of the picture tube has a frame around an inch, which cannot be used for display.