| 摘要 |
PURPOSE:To improve reliability as the total by using an incandescent lamp as lighting of a liquid crystal display element while, when a filament is broken down, automatic switching is made to the other incandescent lamp. CONSTITUTION:A rod-shaped incandescent lamp 3 and a preparatory incandescent lamp 4 covered by a case 2 are provided on the back of a liquid crystal display element 1. When a filament 8 is broken down, the interruption occurs between a collector and an emitter of a transistor 9 for interruption detection, a current flows to a base of a transistor 10 for a conductive circuit through a base resistor 11, a space between the collector and the emitter is made conductive so that the preparatory incandescent lamp 4 is lighted. Thereby, even when the incandescent lamp 3 on one side is broken down, switching is made to the preparatory incandescent lamp 4 so that high reliability is obtained as the total. |
