Abstract: Circuits, methods, apparatus, and systems for recovering a clock from a spread spectrum signal having a periodic modulation profile. The circuits generally include an error detector circuit configured to compare the spread spectrum signal and a recovered clock signal, and to produce a first error signal corresponding to the periodic modulation profile and a second error signal corresponding to phase differences other than the spread spectrum modulation, a record and playback unit configured to record a value to a frequency memory, said value based on the first error signal and produce a third error signal corresponding to a predicted periodic modulation based at least in part on the recorded value, and a signal generator configured to produce the recovered clock signal in response to the second and third error signals.

Abstract: An optical pick-up device comprises a light source, a light beam switching unit, a light intensity change unit and a signal detection unit including photodiodes.A light beam emitted from the light source and irradiated on an information recording medium has a wavelength for recording information and a wavelength, different from the former, for the reproducing information. The light beam switching unit carries out switching between a light having the wavelength for recording information and a light having the wavelength for reproducing information.The light intensity change unit transmits or reflects the light beam having the wavelength for recording information with attenuation to prevent a saturation of the photodiodes and transmits or reflects the light beam having the wavelength for reproducing information without attenuation. The light beam thus produced is detected by the signal detecting unit, and the servo control such as focusing servo, etc. is carried out on the basis of the detected signal.

Abstract: A surface acoustic wave (SAW) pickup and record stylus is constructed from an elongated substrate which supports the propagation of SAW. The substrate is tapered to a tip at one end and a fan-shaped interdigital electrode structure having curved fingers is formed thereon. During operation in the pickup mode a beam of SAW is focused to the tip of the stylus which is arranged in contact with a record medium. During playback, the beam reflected by the record medium generates a signal in the interdigital electrode of the stylus representative of the acoustic conditions at the stylus tip and, correspondingly, of the information recorded on the record medium surface. In the record mode the stylus is brought into contact with a record medium. During recording, the input power applied to the interdigital electrode is increased to effect a deformation of the surface of the record medium representative of the information to be recorded.