| 摘要 |
PURPOSE:To effectively prevent a light emitting element from deteriorating and damaging due to the runaway of a CPU by providing a converter for converting a first control signal to a signal for preventing the light emitting element from continuously emitting a light according to an abnormal pulse when CPU malfunctions so that the second control signal becomes an abnormal pulse. CONSTITUTION:A first control signal S1 for controlling ON/OFF of a light emitting element LED and a second control signal S2 for validating or invalidating an ON signal of the first control signal S1 of a device for sequentially scanning a plurality of light emitting elements LED by a pulse drive are output through CPU. The signal S2 validates the ON signal only for a predetermined period after output, and is a pulse signal output at the interval of a predetermined period or longer for invalidating the ON signal for a predetermined period after the period. A converter for converting the signal S1 to a signal for preventing the light emitting element LED from continuously emitting a light when CPU malfunctions so that the signal S2 becomes an abnormal pulse is provided. The converter is composed, for example, of monostable multivibrators 3a, 3b. |
