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US 7,079,475 B2Granted
Pre-pit information-detecting apparatus, optical-information detecting apparatus, program, and computer-readable information-recording medium
AssigneeRicoh Company, Ltd.
InventorKei Hagiwara
Life of this patent
Estimating the term…
Abstract
An apparatus for detecting pre-pit information is disclosed, including an optical pickup, an optical-detecting section, a difference-detecting circuit, a first peak-value detecting circuit, a filtering circuit, a second peak-value detecting circuit, a differential potential-dividing circuit, and a comparator.
Claims22
An apparatus for detecting pre-pit information, comprising:
- an optical pickup configured to irradiate a light beam onto an optical-information recording medium having guiding grooves to be an information-recording track and pre-pits preset in between the guiding grooves;
- an optical-detecting section configured to optically detect said light beam reflected at said optical-information recording medium, having at least two optical-detecting regions divided across said track;
- a difference-detecting circuit configured to detect a difference between respective signals output from said two optical-detecting regions of the optical-detecting section;
- a first peak-value detecting circuit configured to detect and output a peak value of a signal output from the difference-detecting circuit;
- a filtering circuit configured to extract a signal based on wobble of said guiding grooves from the signal output at said difference-detecting circuit;
- a second peak-value detecting circuit configured to detect and output a peak value of a signal output from the filtering circuit;
- a differential potential-dividing circuit configured to divide at a predetermined proportion and output a difference between the output value of said first peak-value detecting circuit and the output value of said second peak-value detecting circuit;
- and
- a comparator configured to compare the output of said difference-detecting circuit and the output of said differential potentially-dividing circuit so as to output information regarding said pre-pits,
- wherein at least one of said first peak-value detecting circuit and said second peak value detecting circuit is made of a maximum-amplitude holding circuit for holding a maximum-amplitude voltage and includes a drop-rate selecting section for selecting multiple setting values as drop rates of the holding voltage.
7 more elements
An apparatus for detecting pre-pit information, comprising:
- an optical pickup configured to irradiate a light beam onto an optical-information recording medium having guiding grooves to be an information-recording track and pre-pits preset in between the guiding grooves;
- an optical-detecting section configured to optically detect said light beam reflected at said optical-information recording medium, comprising at least two optical-detecting regions divided across said track;
- a difference-detecting circuit configured to detect a difference between respective signals output from said two optical-detecting regions of the optical-detecting section;
- a first voltage-detecting circuit configured to detect and output a peak voltage of a difference signal output from the difference-detecting circuit;
- a filtering circuit configured to eliminate from said difference signal a detected pre-pit component;
- a second voltage-detecting circuit configured to detect and output a peak voltage or average voltage of a signal output from the filtering circuit;
- a differential potential-dividing circuit configured to divide at a predetermined ratio and output a difference between the output voltage of said first voltage-detecting circuit and the output voltage of said second voltage-detecting circuit;
- and
- a comparator configured to compare said difference signal and output voltage of said differential potential-dividing circuit so as to output information regarding said pre-pits,
- wherein at least one of said first voltage-detecting circuit and said second voltage-detecting circuit is made of a maximum-amplitude holding circuit for holding a maximum-amplitude voltage and includes a drop-rate selecting section for selecting multiple setting values as drop rates of the holding voltage.
7 more elements
Dependencies are inferred from the claim text.