Abstract: An optical disc reproducing apparatus can play multiple types of discs. The apparatus biases a focusing error signal based on the disc type. An analyzer receives reflected light of a light beam irradiated from an optical pick-up to a disc. A focus error signal is generated based on the signal supplied the analyzer. A switch selectively provides one of first and second bias voltages. A control controls which of the first and second bias voltages the switch provides based on the type of disc. The bias voltage is added to the focus error signal. An object lens of the optical pickup is driven based on the focus error signal with the bias voltage added.

Abstract: A magnet-optical disk drive device comprises a disc driving mechanism which includes a drive shaft powered by an electric motor. A magnet-optical disc is detachably connected to the drive shaft. A magnetic field modulation head is positioned at one side of the disc, and an optical unit is positioned at the other side of the disc. A moving mechanism is employed for moving both the magnetic field modulation head and the optical unit in a radial direction of the disc. The magnetic field modulation head is of a floating type wherein a head proper is forced to float above the surface of the disc due to the force of an air flow which is produced when the disc is rotated.

Abstract: A disc reproducing apparatus for reproducing voice data recorded on an optical disc by successive predetermined amounts and recording the reproduced data temporarily in a RAM for subsequent continuous reproduction, and a disc recording apparatus for reading out the voice data written in RAM by successive predetermined amounts for recording on the optical disc.

Abstract: A radio transmitter apparatus arranged such that transmission efficiency is improved by switching the load impedance on the final stage in response to the power source voltage or the transmission output power.