Ignition control apparatus for an internal combustion engine

Claim 1

An ignition control apparatus for an internal combustion engine having a power supply, cylinders, and spark plugs each of which is mounted on each of said cylinders, comprising: a signal generating means for generating electrical signals which indicate the conditions of said engine; a first electrical circuit, which would be inoperable at low voltages from the power supply which may occur at the time of starting the engine, for calculating ignition timing of each of said spark plugs in response to the value of said electrical signals, and for generating a control signal based on said calculated ignition timing; a second electrical circuit for generating a control signal based on ignition timing of a fixed spark-advance angle, said second electrical circuit comprising a C-MOS type electrical circuit which is operable at low voltages from the power supply which may occur at the time of starting the engine; a third electrical circuit for controlling the timing of sparks produced by said spark plugs in response to the value of a control signal provided from either one of said first electrical circuit and said second electrical circuit; and a switching means which is automatically changed over and controlled for applying said control signal from said second electrical circuit to said third circuit at the time of starting said engine and for applying said control signal from said first electrical circuit to said third circuit during periods of operation of the engine other than at the time of starting the engine.