Printing control apparatus compatible with printing systems of a laser scanning unit type and a light emitting diode type

A printing control apparatus of an electrophotographic printing system, comprising:

• synchronizing signal supplying means for receiving at least one signal out of a light emitting diode horizontal synchronizing signal generated when a period of a horizontal synchronizing signal of a light emitting diode type printing system coincides with a given counting period and a beam detecting signal generated by a laser scanning unit, and supplying a horizontal synchronizing signal corresponding to a printing system in response to a synchronizing select signal;
• clock generating means connected to said synchronizing signal supplying means, for determining said counting period, generating a reference clock for the generation of a plurality of signals, for generating a video clock from said reference clock in response to said horizontal synchronizing signal and for generating a latch driving signal from said reference clock in response to said synchronizing select signal;
• latch signal generating means connected to said clock generating means, for generating a data latch signal having a given period form said reference clock in response to said latch driving signal;
• strobe signal generating means for generating strobe signals for enabling emission of energy from a light emitting diode array by shifting said reference clock in response to said data latch signal;
• data output means for generating video data to be printed according to a mode select signal;
• and
• control signal generating means for providing said synchronizing select signal to said synchronizing signal supplying means by latching an external control signal, providing said mode select signal to said data output means, and providing a laser diode signal and a laser scanning unit motor control signal to a laser scanning unit of a laser scanning type printing system.