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US 5,499,226 AGranted
Optical information reproduction apparatus and optical information reproduction method
AssigneeCanon Kabushiki Kaisha
InventorsShinichi Ohta, Hiroto Kitai
Life of this patent
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Abstract
In an optical information reproduction apparatus, digital information recorded as an optical mark on an optical information recording medium is reproduced in the following manner. A light beam is applied to the recording medium, and the obtained reproduction signal is binarized. The binary reproduction signal is sampled by a sampling clock which is generated by a PLL control signal generator, and is synchronized with the binary reproduction signal so as to reproduce the digital information. The PLL control signal generator achieves synchronization based on the leading and trailing edges of a change point of the binary reproduction signal.
Claims18
An optical information reproduction apparatus comprising:
- means for reading out digital information recorded as an optical mark on an optical information recording medium as an information reproduction signal by scanning the recording medium with a light beam;
- conversion means for converting the information reproduction signal into a binarized reproduction signal;
- means for generating a first signal corresponding to leading and trailing edges of a change point of the binarized reproduction signal;
- means for generating a sampling clock signal;
- means for generating a second signal which oscillates at a frequency at least twice a frequency of the sampling clock signal;
- phase comparison means for generating a phase advance signal and a phase delay signal, the phase advance signal being a signal which indicates a phase difference between the first signal and the second signal, the phase delay signal having a pulse width equal to the second signal;
- and
- means for reproducing the digital information by sampling the binarized reproduction signal with the sampling clock signal on the basis of the phase advance signal and the phase delay signal.
5 more elements
An optical information reproducing apparatus comprising:
- means for reading out digital information recorded as an optical mark on an optical information recording medium as an information reproduction signal by scanning the recording medium with a light beam;
- conversion means for converting the information reproduction signal into a binarized reproduction signal;
- means for generating a first signal corresponding to leading and trailing edges of a change point of the binarized reproduction signal;
- means for generating a sampling clock signal;
- phase comparison means for generating a first output indicative of a phase difference between the first signal and the sampling clock signal and for comparing the first output with a second output which is a predetermined pulse;
- and
- means for reproducing the digital information by sampling the binarized reproduction signal with the sampling clock signal on the basis of a signal from said phase comparison means.
4 more elements
An optical information reproducing apparatus comprising:
- means for reading out digital information recorded as an optical mark on an optical information recording medium as an information reproduction signal by scanning the recording medium with a light beam;
- conversion means for converting the information reproduction signal into a binarized reproduction signal;
- means for generating a first signal corresponding to leading and trailing edges of a change point of the binarized reproduction signal;
- means for generating a sampling clock signal;
- phase comparison means for detecting a phase difference between a signal obtained by delaying the first signal and the sampling clock signal;
- and
- means or reproducing the digital information by sampling the binarized reproduction signal with the sampling clock signal on the basis of a signal from said phase comparison means.
4 more elements
An optical information reproducing method comprising the steps of:
- reading out digital information recorded as an optical mark on an optical information recording medium as an information reproduction signal by scanning the recording medium with a light beam;
- converting the information reproduction signal into a binarized reproduction signal;
- generating a first signal corresponding to leading and trailing edges of a change point of the binarized reproduction signal;
- generating a sampling clock signal;
- generating a second signal which oscillates at a frequency at least twice a frequency of the sampling clock signal;
- generating a phase advance signal indicative of a phase difference between the first signal and the second signal and a phase delay signal having a pulse width equal to the second signal;
- and
- reproducing the digital information by sampling the binarized reproduction signal with the sampling clock signal on the basis of the phase advance signal and the phase delay signal.
5 more elements
An optical information reproducing method comprising the steps of:
- reading out digital information recorded as an optical mark on an optical information recording medium as an information reproduction signal by scanning the recording medium with a light beam;
- converting the information reproduction signal into a binarized reproduction signal;
- generating a first signal corresponding to leading and trailing edges of a change point of the binarized reproduction signal;
- generating a sampling clock signal;
- generating a first output indicative of a phase difference between the first signal and the sampling clock signal and comparing the first output with a second output which is a predetermined pulse;
- and
- reproducing the digital information by sampling the binarized reproduction signal with the sampling clock signal on the basis of a result of the comparing in said first output generating step.
4 more elements
An optical information reproducing method comprising the steps of:
- reading out digital information recorded as an optical mark on an optical information recording medium as an information reproduction signal by scanning the recording medium with a light beam;
- converting the information reproduction signal into a binarized reproduction signal;
- generating a first signal corresponding to leading and trailing edges of a change point of the binarized reproduction signal;
- generating a sampling clock signal;
- detecting a phase difference between a signal obtained by delaying the first signal and the sampling clock signal;
- and
- reproducing the digital information by sampling the binarized reproduction signal with the sampling clock signal on the basis of a result of said detecting step.
4 more elements
Dependencies are inferred from the claim text.