| 摘要 |
When a "screen saver" operates to display a homogeneous black picture image after the same image is continuously displayed on a CRT (10) for a constant period of time, a power supply (3) for a CRT display unit is controlled to be turned off, thereby preventing the CRT display unit from being left for a long time in a power-on state. Namely, a waiting time for 3 minutes, for example, is provided when the "screen saver" so operates that the CRT displays a homogeneous black picture image to turn off a power circuit (9) for the CRT, and then a heater (14) for the CRT is turned off after a lapse of a prescribed period of time within 5 to 60 minutes, for example. A function for enabling such an operation of the "screen saver" may be provided in an extension graphics board (51) which is inserted in an open slot (53) provided in a computer of an open architecture type. In this case, the graphics board (51) is provided with an input detection part (68) including a keyboard access detection part (78) for detecting an address signal which is supplied to an address bus (66) in response to manipulation of a keyboard (57), and an interruption request detection part (77) for detecting an interruption signal which is outputted in response to manipulation of a mouse (58) respectively. A timer (69) is reset when the input detection part (68) detects presence of an input signal from the keyboard (57) or the mouse (58). When no reset signal is supplied from the input detection part (78) again before a lapse of a period of time which is previously set in the timer (69), a blank signal is supplied to the CRT display unit. <IMAGE> |
