Optical record carrier having position indentifying track modulation
First Claim
1. Apparatus for recording and/or reading an information signal in an elongated track on an optical record carrier, which track is modulated by a periodic position-identifying signal having a frequency which is synchronous with a clock signal, said position-identifying signal identifying the locations of successive positions along said track;
- such apparatus comprising means for scanning said track with a beam of radiation which is reflected therefrom, optical detecting means for detecting the reflected beam and generating a detection signal corresponding to the modulation of such beam caused by the track modulation, and a detection circuit for deriving said position-identifying signal from said detection signal;
characterized in that;
said position-identifying signal comprises successive digital code signals at successive locations on said track the same as those where said information signal is recorded thereon, each digital code signal being in the form of modulated excursions of said track in a direction substantially transverse thereto; and
said position-identifying signal is in a frequency band substantially outside the frequency band of said information signal.
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Accused Products
Abstract
A system for recording and/or reading an information signal (Vi) on an elongated track (4) of an optically readable record carrier (1). A position-identifying signal (Vp) which is synchronous with a clock signal is recorded on the track 4 by modulating the transverse excursion of the track, the signal Vp indicating the instantaneous position along the track at which the information signal Vi is located. The frequency band of the position-identifying signal Vp is situated substantially outside the frequency band of the information signal Vi. In manufacturing such a record carrier, the deflection of a recording beam of radiation in a direction substantially transverse to the track is modulated by the position-information signal Vp.
62 Citations
16 Claims
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1. Apparatus for recording and/or reading an information signal in an elongated track on an optical record carrier, which track is modulated by a periodic position-identifying signal having a frequency which is synchronous with a clock signal, said position-identifying signal identifying the locations of successive positions along said track;
- such apparatus comprising means for scanning said track with a beam of radiation which is reflected therefrom, optical detecting means for detecting the reflected beam and generating a detection signal corresponding to the modulation of such beam caused by the track modulation, and a detection circuit for deriving said position-identifying signal from said detection signal;
characterized in that;said position-identifying signal comprises successive digital code signals at successive locations on said track the same as those where said information signal is recorded thereon, each digital code signal being in the form of modulated excursions of said track in a direction substantially transverse thereto; and said position-identifying signal is in a frequency band substantially outside the frequency band of said information signal. - View Dependent Claims (2, 3, 4, 5)
- such apparatus comprising means for scanning said track with a beam of radiation which is reflected therefrom, optical detecting means for detecting the reflected beam and generating a detection signal corresponding to the modulation of such beam caused by the track modulation, and a detection circuit for deriving said position-identifying signal from said detection signal;
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6. A method of manufacturing an optical record carrier on which an information signal is to be recorded in a radiation-sensitive track thereon, which track is modulated in accordance with a periodic position-identifying signal identifying the locations of instantaneous positions along said track;
- such method comprising;
scanning said record carrier with a radiation beam which traverses a scanning path corresponding to a desired pattern of said track on said record carrier and having a substantially constant scanning velocity; modulating said radiation beam with said position-identifying signal during such scanning, such position-identifying signal comprising successive digital code signals at successive positions on said track the same as those where said information signal is to be recorded thereon, each code signal digitally modulating the excursion of the track in a direction substantially transverse thereto, said position-identifying signal being in synchronism with a clock signal having a frequency corresponding to the scanning velocity of said radiation beam; and providing said position-identifying signal in a frequency band which is substantially outside the frequency band of the information signal to be recorded on said track. - View Dependent Claims (7, 8, 9)
- such method comprising;
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10. Apparatus for manufacturing an optical record carrier for recording an information signal in a radiation-sensitive elongated track thereon, which track is modulated by a periodic position-identifying signal identifying the locations of successive positions along said track;
- such apparatus comprising;
an optical system for scanning said record carrier with a radiation beam which traverses a scanning path which forms said track in a desired pattern thereon; means for generating said position-identifying signal in synchronism with a clock signal, said position-identifying signal comprising successive digital code signals at successive positions on said track the same as where said information signal is to be recorded thereon; and means for modulating said radiation beam in accordance with said, code signals during said scanning of the record carrier, each code signal digitally modulating the excursion of the track at its position in a direction substantially transverse to the track; said position-identifying signal being in a frequency band which is substantially outside the frequency band of the information signal to be recorded on said track. - View Dependent Claims (11, 12, 13)
- such apparatus comprising;
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14. A record carrier having on a surface thereof an optically readable elongated track on which information may be recorded or read by read/record apparatus which scans such track with a beam of radiation;
- characterized in that;
excursions of said track in a direction substantially traverse thereto are digitally modulated at successive positions on said track in accordance with a position-identifying signal comprising successive digital position code signals which identify the locations of such positions on said track, whereby the locations of information recorded in such positions are identified; and said transverse excursions of said track are further digitally modulated at said positions in accordance with synchronizing signals included in said position-identifying signal between the successive digital position code signals, such synchronizing signals enabling the read/record apparatus to maintain a constant scanning speed of said beam of radiation on said track. - View Dependent Claims (15, 16)
- characterized in that;
Specification