Pioneer Corporation

Junji Tanaka

Hiroshi Hikima

Shin Akabane

Naoharu Yanagawa

Takakazu Sugiyama

When record information is recorded on a recording medium with recording control information pre-recorded thereon by forming pre-pits so that the recording control information will be used to control the recording of the record information to be recorded on the recording medium, a first light beam having first power and a second light beam having second power different from the first power are irradiated to the pre-pits on a time-shared basis according to the record information to generate read signals generated from electrical signals according to the amounts of reflected light of the respective beams so that the pre-pits will be detected from inputs of the read signals. In this configuration, the pre-pits are detected from only the read signals input during a period of irradiation of the second light beam.

Pre-pit detecting apparatus detecting pre-pit signal from only signals input during period of applying light beam having reproducing power

An information recording/reproducing apparatus irradiates a light beam on an optical disc on which pre-pits are formed, and performs recording and/or reproduction of information with respect to the optical disc according to a recording clock produced based on a wobble signal and a pre-pit signal. When recording information onto the optical disc having the pre-pits, a light beam is radiated to thereby extract the wobble signal and pre-pit signal. Then, according to the wobble signal and the pre-pit signal, a recording clock signal is produced, and information is recorded based on the recording clock signal. When producing a pre-pit signal, a push-pull signal is produced from the reflected light from the optical disc, and this signal is compared with a reference level to thereby detect a pre-pit. Here, when a pre-pit is not detected, the reference level is changed and the detection processing of the pre-pits is executed again.

Apparatus and method for re-executing pre-pit detection if pre-pits are not detected after changing reference level

A composite signal in which pre-pit signal components are piggypacked onto frequency components of wobbling, is extracted from an optical recording medium. The composite signal is binarized, so that pre-pit signals are generated. The pre-pit signals pass through a first gate when the gate is open. The gate is periodically opened only in a period during which the amplitude of the wobbling becomes a maximum one. The number of the pre-pit signals passing through the gate is counted, so that a binarizing level for generating the pre-pit signal is set based on the relationship between the counted number per a reference time and a predetermined reference number.

Pre-pit detecting device and binarizing level setting method

A prepit detection unit for detecting prepits in an optical recording and reproducing apparatus for recording and reproducing information on a recordable, optical record medium including preinformation such as address information in a prepit form. In the prepit detection unit, for first and second divisional RF signals output from a pickup being divided into a first divisional light reception part and a second divisional light reception part by a division line optically parallel to the tangential direction of an information track for receiving reflected light from the optical record medium, mark sections and space sections are clamped by potential correction circuits and a difference is found by a radial push-pull circuit.

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Tokorozawa, Japan

Junji Tanaka