Abstract: The present invention relates to digital protection circuits in a CRT based display system for the purpose of providing hardware protections to the system before exactly removing a crisis. Self-testing and diagnostic capabilities are also supplemented in a CRT based monitor that are used to lacking in the monitor. The protection circuit basically includes a microprocessor section, a timer section, a register section, a digital to analog converter section, an analog to digital converter section, a non-volatile memory section, and an analog section. All sections can be integrated in a single chip and share a single controller. By using two diodes with their negative terminals coupled together to supplement capabilities of self-testing and diagnostic even when lack of power supplying. All implementations mentioned above can be easily achieved at a very low additional cost.

Abstract: A single chip display system processor in a CRT (Cathode Ray Tube) based display is disclosed, including a display system controller, a horizontal processor, a vertical processor, and optionally, the on screen display (OSD) processor. The horizontal processor, a vertical processor, and the on screen display (OSD) processor are under control by the display system controller. This single chip display system processor also controls some elements of the CRT based display, such as power horizontal deflection circuit, power vertical deflection circuit, video processor, the power video circuit, power supply for the electronics and CRT, and the user front panel. The display system processor encompasses a phase lock loop (PLL) circuit within the horizontal processor that compares incoming horizontal signal with the feedback signal from power horizontal deflection circuit for the purpose of synchronizing incoming video signals to display stable image in the CRT based display system.