LCM provides users with a standard LCD display driver interface (4-bit, 8-bit, VGA and other different types). Users operate according to the interface requirements to control the LCD to display correctly. Compared with glass, LCM is a more integrated LCD product. For small-size LCD displays, LCM can be easily connected to various microcontrollers (such as single-chip microcomputers); however, for large-size or color LCD displays, it generally occupies a considerable part of the control system resources or cannot be controlled at all. For example, a 320×240 256-color color LCM displays at 20 fields/second (that is, full-screen refresh display 20 times in 1 second). The amount of data transmitted in one second is as high as: 320×240×8×20=11.71875Mb or 1.465MB. If the standard MCS-51 series single-chip microcomputer is used to process it, assuming that the MOVX instruction is repeatedly used to continuously transmit this data, considering the address calculation time, at least a 421.875MHz clock is required to complete the data transmission. It can be seen that the amount of data processed is huge.
The resolution of a fax is also called the scanning density. The higher the resolution, the higher the scanning accuracy. It can be divided into vertical resolution and horizontal resolution. Vertical resolution refers to the number of pixels displayed per millimeter on a vertical horizontal line, and horizontal resolution refers to the number of pixels displayed per millimeter on a parallel horizontal line. According to the international standards for three types of fax machines, the horizontal resolution is 8 pixels/mm, so the resolution of a fax machine is generally expressed as 8 pixels/mm×vertical pixels/mm. Generally, we omit the horizontal resolution and only express the resolution in terms of vertical resolution. There are three main types of vertical resolution: standard 3.85 pixels/mm, fine 7.7 pixels/mm, and super fine 15.4 pixels/mm.