The composition and operation principle of CRT character display
The core component of the CRT display is its cathode ray tube. After introducing the composition and operating principle of the cathode ray tube, the other components of the CRT display will be explained next. For the character display, it is the scan control logic, display memory and character generator, which use various digital circuits. Achieved. The monitor, display memory and character generator used in the PC are placed on the display card inserted in the host computer, and the terminal used in the small computer supporting the multi-user system is scanned for control logic, display memory and character generator All are placed in the controller of the terminal device itself.
The movement of the electron beam on the display screen according to a certain trajectory is called scanning, and the circuit that controls the trajectory of the electron beam is called the scan control logic component. Common scanning methods include raster scan (Raster Scan) and random scan (Random Scan). Species, the performance and price of the two are quite different.
In the raster scan mode, the electron beam scans the entire screen from left to right and from top to bottom. The scan control itself does not need to distinguish what position is to be displayed and what point is not displayed. It only controls the electron beam on the entire screen Move repeatedly on the screen, and the specific content displayed is provided through another logic circuit. In this scanning mode, there are two schemes: progressive scanning and interlaced scanning. Progressive scanning starts from the top of the screen and sequentially scans all the lines in sequence (the line here refers to the line formed by dots in the dot matrix) , Interlaced scanning is to scan all lines with odd line numbers this time, and scan all lines with even line numbers next time. Interlaced scanning is commonly used in television. Because the raster scan and the TV system use the same technology, the technology is mature, the product is cheap, and it is widely used in computer monitors. Its disadvantage is that it has more scanning redundancy time and lower resolution, so it is mainly used for popular character displays.
In the random scanning mode, the electron beam only scans the position on the screen where the content is displayed, rather than the entire screen. Therefore, this scanning mode has a fast drawing speed and high resolution, so it is mainly used for high-quality graphic displays. The disadvantage is that its scanning control logic is more dedicated and complicated, the product production volume is not large enough, and the price is relatively high.
HDI is the English abbreviation for High Density Interconnector. High-density interconnect (HDI) manufacturing is one of the fastest growing areas in the printed circuit board industry. From the first 32-bit computer from HP in 1985 to the large client server with 36 sequential multi-layer printed boards and stacked micro-vias, HDI/mini via technology is undoubtedly the future PCB architecture. Smaller ASICs and FPGAs with smaller device spacing, I/O pins, and embedded passives have shorter rise times and higher frequencies, all of which require smaller PCB feature sizes, which drives Strong demand for HDI/mini vias.
HDI process
First-order process: 1+N+1
Second-order process: 2+N+2
Third-order process: 3+N+3
Fourth-order process: 4+N+4
Buried Hole Pcb,Blind Hole Pcb,Buried Blind Hole Pcb,Multilayer Blind Buried Hole Pcb
Chuangying Electronics Co.,Ltd , https://www.cwpcb.com