| 摘要 |
PURPOSE: An OSD(On Screen Display) device is provided to display on screen signals only by controlling on/off operation of transistors, regardless of the existence of input signals without any additional semiconductor device or circuit. CONSTITUTION: A microprocessor(28) receives external composite video signals, and vertical and horizontal synchronizing signals(39,38) from the LCD unit(40). Then the microprocessor(28) outputs video signals(R,G,B) and FB(Fast Blanking) signals(30) for OSD. A video signal mixing unit(22), installed between the LCD unit and the microprocessor, mixes video signals(24) and the signals for OSD to generate composite video signals. A panel driver(25) installed inside the LCD unit outputs the vertical and horizontal synchronizing signals. A transistor(TR1) ,installed between the video signal mixing unit and a base voltage source, controls the supplying of composite signals extracted from the video signal mixing unit to the LCD unit. |
