OSD vertical blanking signal selection circuit for display apparatus

摘要

An on-screen display (OSD) vertical blanking signal selection circuit for a display apparatus comprises: a microcomputer for generating a reference oscillating signal in response to vertical and horizontal synchronous signals from a video card; an HV processor for generating a flyback transformer (FBT) drive signal and horizontal and vertical drive signals in response to the reference oscillating signal from the microcomputer and the horizontal and vertical synchronous signals from the video card; an FBT for generating a high voltage in response to the FBT drive signal from the HV processor and for supplying the generated high voltage to a cathode ray tube; a horizontal deflection circuit for controlling horizontal deflection of electron beams in a cathode ray tube in response to the horizontal drive signal from the HV processor; a vertical deflection circuit for controlling a vertical deflection of the electron beams in the cathode ray tube in response to the vertical drive signal from the HV processor; and an OSD vertical blanking signal selector for supplying the vertical synchronous signal from the video card or a vertical blanking signal from the vertical deflection circuit as an OSD vertical blanking signal to an OSD circuit in response to a control signal from the microcomputer.