Optical memory playback apparatus

An optical memory playback apparatus, which comprises:

• a medium having information stored therein in the form of an arrangement of reflective regions and nonreflective regions,
• an electroluminescent semiconductor element adapted to emit a light through one end surface thereof for reading out the information from the medium,
• a rod lens serving to lead the light emitted from the electroluminescent semiconductor element onto the medium and return the light reflected from the medium to the end surface of the electroluminescent semiconductor element,
• a cartridge having the electroluminescent semiconductor element and the rod lens incorporated therein with their optical axes coinciding with each other, a cartridge holder drive means having the cartridge held in a state freely movable in the lateral direction and the perpendicular direction with respect to the medium,
• a signal processing unit serving to detect the change of terminal voltage of the electroluminescent semiconductor element due to the self-coupling effect brought about by the returned light from the medium,
• an information reproduction means for reproducing the information in accordance with the signal received from the signal processing unit,
• a focusing control means serving to issue a signal to the cartridge holder drive means in accordance with the signal from the signal processing unit for thereby controlling the focal point of the light being sent to the medium, and
• a tracking control means serving to issue a signal to the cartridge holder drive means in accordance with the signal from the signal processing unit for thereby controlling the tracking of the light being sent to the medium.