| 摘要 |
PURPOSE:To achieve prevention of degradation in a carborne CRT by a method wherein CRT cathode filaments are elecrically energized for a specificed fime starting from the inputting of a door opening/closing detection signal and the display of the CRT is made as soon as passenger gets on a car by interrupting the energization on a key removal detection signal. CONSTITUTION:An energization command generation circuit 30 enables the lighting of a key hole lighting bulb 36 and a aisle light lighting bulb 38 until 10-15 sec elapses after the closing of a door and an energization command 100 is fed to a preheating power source circuit 18 to preheat cathode filaments 14A-14C of a CRT12. Therefore, the CRT12 starts the display action immediately at the starting time when the action of a display 10 starts by the operation of the starting switch. Then, when it is judged from the key removal detection signal 102 that the key is not inserted into the starting switch, a transistor 86 is turned ON and a transistor 78 turned OFF to interrupt the command 100 by the opening of a relay switch 70. Therefore, when the passenger gets off a car, the filaments 14A-14C will not be energized and hence, no preheating is done, which can inhibit the degradation of the CRT12 and the lowering of the life. |
