Light control circuit of optical disc system

摘要

A light control circuit of an optical disc system for controlling light from a light emitting element at a read power level even if a write data operation is performed. The light control circuit includes a light control circuit, a superimposedly energizing circuit for providing a light for data write and a subtraction circuit for subtracting a predetermined current from a light sensing element. A light control circuit may further include a reference value setting circuit for automatically finding and determining reference values of a read power level, a write power level, and a subtraction value. The reference values may be defined with respect to an origin of the characteristic of the light emitting element where a current flowing through the light emitting element is substantially zero. Alternatively, the reference values may be defined with respect to another origin of the characteristic of the light emitting element where a current flowing through the light emitting element is near to a current providing the first predetermined level.