Patent ID: 8490516

Claim:
A screw driving machine comprising: a housing; a bit that is movable from a first position to a second position relative to the housing to strike a screw against a workpiece and that is rotatable about an axis thereof to rotate the screw to the workpiece; a push lever that is movable between a third position and a fourth position relative to the housing, the push lever moving from the third position to the fourth position when pressed against the workpiece; a combustion-type power mechanism that defines a combustion chamber when the push lever is located at the fourth position, the combustion-type power mechanism including a spark plug that ignites combustible gas filled in the combustion chamber to apply striking force to the bit toward the second position, causing the bit to strike the screw, the spark plug igniting the combustible gas when supplied with electric power; a motor that generates a rotative force when supplied with electric power; a power transmission mechanism that transmits the rotative force generated at the motor to the bit, causing the bit to rotate; a trigger to be operated by an operator; a power source that supplies the electric power to both the spark plug and the motor; a first contact switch that outputs a first signal when the first contact switch detects the movement of the push lever; a second contact switch that outputs a second signal when the second contact switch detects the operator's operation on the trigger; and a control unit that supplies the electric power from the power source to the spark plug at a first timing based on outputting one or both of the first signal and the second signal, and that supplies the electric power to the motor at a second timing based on outputting one or both of the first signal and the second signal.