Control circuit for light-emitting element

A control circuit configured to generate a driving signal for driving a light-emitting element, comprising:

• an external synchronization oscillator configured to receive a synchronization clock signal from an external circuit, and to generate an external synchronization cyclic signal synchronously with the synchronization clock signal;
• an internal oscillator configured to generate an internal cyclic signal having a predetermined frequency asynchronously with the synchronization clock signal;
• and
• a driving signal generating unit configured such that, when the frequency of the external synchronization cyclic signal is within a predetermined range, the driving signal generating unit generates the driving signal based upon the external synchronization cyclic signal, and such that, when the frequency of the external synchronization cyclic signal deviates from the predetermined range, the driving signal generating unit generates the driving signal based upon the internal cyclic signal.