| 摘要 |
An ignition timing control device for an internal combustion engine is provided with a microcomputer which determines the ignition timing (i.e., the angles BTDC) on the basis of a measurement of the period between successive pulses of a crankshaft angle signal in each ignition cycle. The device comprises, in addition to other conventional components, an rpm level judgement device, for determining whether the rpm of the engine is above a predetermined level or not. At the start of each ignition control cycle, this determination of the rpm level is effected on the basis of the measurement of the period of the crankshaft angle signal performed in the immediately preceding ignition cycle. When the rpm is judged to be above the predetermined level, the ignition timing signal is generated in accordance with the value of the ignition timing which has been determined in the preceding ignition cycle; when, on the other hand, the rpm is judged to be not above the predetermined level, the ignition timing signal is generated in accordance with the value of the ignition timing which is determined in the current ignition cycle.
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