| 摘要 |
PURPOSE:To automatically carry out the checking of lamps and as well to make it possible to prevent transient abnormal indication upon the starting of an engine, by turning on and off the lamp in a predetermined period from the starting of the engine. CONSTITUTION:When an engine operating signal becomes H-level a timer 1 is triggered so that the H-level is maintained in a predetermined time period, such as, for example, 10sec., and then switched to L-level. In this period both inputs of a first AND gate 2 are H-level and therefore the output thereof is also H-level so that pulses are generated from an oscillating circuit 3 at a predetermined synchronization and a lamp 71 is turned on and off by means of a transistor 72. And since the output of the timer 1 becomes L-level after the predetermined time period, the transistor 72 is cut-off so that the lamp 71 is lit off. Thus, the turning-on and off of the lamp is carried out irrespective of detecting signals, thereby the checking of the lamp is surely carried out. After that, the signal level is reversed into H-level through a NOT circuit 5 and is delivered to a second AND gate 6 for alarming abnormality by the detecting signal input H. |
