Pre-pit detecting apparatus
AssigneePioneer Corporation
InventorHiroshi Hikima
Life of this patent
Estimating the term…
Abstract
When first and second read signals generated on the basis of the outputs of electrical signals from a light receiving portion are input to an amplitude correcting circuit, the first and second read signals are added to generate an addition signal. Then the amplitudes of the first and second read signals are corrected for the each RF signal component corresponding to each recording pit, which is contained in the first and second read signals on the basis of the addition signal. Finally, the difference between the first and second read signals is computed to generate a difference signal so that a pre-pit signal will be detected on the basis of the difference signal.
Claims6
A pre-pit detecting apparatus for an optical recording medium, which has information tracks with recording pits carrying record information formed thereon and guide tracks for guiding a light beam to the information tracks, and further has pre-pits carrying pre-information formed on the guide tracks, the pre-pit detecting apparatus including an amplitude correcting circuit, which when the optical beam is irradiated to one of the information tracks, corrects the amplitude of a first read signal and the amplitude of a second read signal generated on the basis of the outputs of electrical signals from a light receiving unit, divided into two parts by a division line at least optically parallel with the information track, such that the pre-pit detecting apparatus performs a computation on the difference between the corrected first and second read signals to generate a difference signal so as to detect a pre-pit signal on the basis of the difference signal, wherein
- said amplitude correcting circuit comprises:
- an addition signal generating device for adding the first read signal to the second read signal to generate an addition signal;
- a first amplitude correcting device for correcting the amplitude of the first read signal, on the basis of the generated addition signal, for an RF signal component corresponding to a recording pit, which is contained in the first read signal;
- and
- a second amplitude correcting device for correcting the amplitude of the second read signal, on the basis of the generated addition signal, for an RF signal component corresponding to a recording pit, which is contained in the second read signal.
Dependencies are inferred from the claim text.