EP0144058A2 — Apparatus for optically writing information

Claim 1

Independent Claim 121 words

In a record carrier having a circular disc-shaped substrate on which a recording layer capable of optically writing information therein is disposed; a record carrier characterized in that a plurality of circumferential reference tracks which extend in a rotating direction are disposed at radial intervals, that each of said reference tracks is divided into a plurality of sectors, that said each sector comprises an address portion including address information of the corresponding reference track, a sector address portion including address information of the corresponding sector, and a synchronous portion including a synchronizing signal, and that said each reference track is constructed into an optically detectable structure so as to function as optical guide for recording information between the adjacent reference tracks.

Claim 2

Dependent Claim 121 words

In a record carrier having a circular disc-shaped substrate on which a recording layer capable of optically writing information therein is disposed; a record carrier characterized in that a plurality of circumferential reference tracks which extend in a rotating direction are disposed at radial intervals, that each of said reference tracks is divided into a plurality of sectors, that said each sector comprises an address portion including address information of the corresponding reference track, a sector address portion including address information of the corresponding sector, and a synchronous portion including a synchronizing signal, and that said each reference track is constructed into an optically detectable structure so as to function as optical guide for recording information between the adjacent reference tracks.

Claim 3

Dependent Claim 19 words

A record carrier according to claim 1, wherein the respective reference tracks are divided into equal numbers of sectors.

Claim 4

Dependent Claim 24 words

A record carrier according to claim 1, wherein said each sector has a fixed length irrespective of the radial position of said reference track.

Claim 5

Independent Claim 229 words

An apparatus comprising a record carrier which has a circular disc-shaped substrate provided thereon with a recording layer capable of optically writing information therein and in which a plurality of circumferential reference tracks extending in a rotating direction are disposed at radial intervals, said each reference track being constructed into an optically detectable structure so as to function as optical guide for recording information between the adjacent reference tracks; an objective lens which condenses first and second light beams so as to focus them on said recording layer of said record carrier respectively; optical detection means to detect intensities of the light beams from said recording layer; means to derive from the output of said optical detection means a tracking signal for controlling impingement positions of the light beams in a direction traversing the track direction; tracking means to cause said first light beam to track the reference track in response to the tracking signal; and light diffraction means to move said second light beam on said recording layer of said record carrier in the radial direction thereof while said second light beam holds a predetermined positional relationship with said first light beam as said first light beam is tracking said reference track; information being written between said reference tracks by said second light beam as one of said reference tracks is being tracked by said first light beam.

Claim 6

Independent Claim 229 words

An apparatus comprising a record carrier which has a circular disc-shaped substrate provided thereon with a recording layer capable of optically writing information therein and in which a plurality of circumferential reference tracks extending in a rotating direction are disposed at radial intervals, said each reference track being constructed into an optically detectable structure so as to function as optical guide for recording information between the adjacent reference tracks; an objective lens which condenses first and second light beams so as to focus them on said recording layer of said record carrier respectively; optical detection means to detect intensities of the light beams from said recording layer; means to derive from the output of said optical detection means a tracking signal for controlling impingement positions of the light beams in a direction traversing the track direction; tracking means to cause said first light beam to track the reference track in response to the tracking signal; and light diffraction means to move said second light beam on said recording layer of said record carrier in the radial direction thereof while said second light beam holds a predetermined positional relationship with said first light beam as said first light beam is tracking said reference track; information being written between said reference tracks by said second light beam as one of said reference tracks is being tracked by said first light beam.

Claim 7

Dependent Claim 38 words

An apparatus according to claim 4, wherein said light diffraction means is an acousto-optic diffracter, and by varying a frequency to be supplied to said acousto-optic diffracter, the impingement position of said second light beam can be altered.

Claim 8

Dependent Claim 40 words

An apparatus according to claim 5, wherein a single light source is comprised, a light beam from said light source is caused to enter said acousto-optic diffracter, and said first and second light beams are emitted from said acousto-optic diffracter.

Claim 9

Dependent Claim 65 words

An apparatus according to claim 6, comprising a first oscillator which generates a signal of a first frequency, a second oscillator which generates a signal of a second frequency different from the first frequency and which can alter the second frequency, and an adder which adds the outputs of said first and second oscillators, said acousto-optic diffracter being driven by an output of said adder.

Claim 10

Dependent Claim 57 words

An apparatus according to claim 6, wherein an oscillator is comprised which generates a signal of a single frequency and which can alter the frequency, said acousto-optic diffracter is driven by the output of said oscillator, and zero-order light and first-order light emitted from said acousto-optic diffracter are respectively used as said first and second light beams.

Claim 11

Dependent Claim 106 words

An apparatus according to claim 5, wherein two light sources are comprised, a light beam from one of said light sources is caused to enter said acousto-optic diffracter so as to use as said second light beam first-order light emitted from said acousto-optic diffracter, a light beam from the other light source is used as said first light beam, an optical device for synthesizing said first and second light beams is disposed in an optical path between the acousto-optic device and said objective lens, and a light beam from said optical device is condensed on said recording layer of said record carrier by said objective lens.

Claim 12

Dependent Claim 39 words

An apparatus according to claim 7, wherein said first and second oscillators are constructed so that the frequencies of their outputs may change in accordance with the tracking signal, and said acousto-optic diffracter serves also as said tracking means.

Claim 13

Dependent Claim 60 words

An apparatus according to claim 4, wherein said light diffraction means is a rotatable transmissive grating, a light beam from a single light source is caused to enter said transmissive grating so as to emit said first and second light beams therefrom, and an emission direction of said second light beam can be altered by rotation of said transmissive grating.

Claim 14

Dependent Claim 50 words

An apparatus according to claim 4, wherein said record carrier is so formed that said each reference track is divided into sectors of fixed length, and means is comprised to control a rotational frequency of said record carrier in accordance with the reference track tracked by said first light beam.

Claim 15

Dependent Claim 22 words

An apparatus according to claim 9, wherein a variable frequency oscillator for driving said acousto-optic diffracter includes a phase locked loop circuit.

Claim 16

Dependent Claim 30 words

An apparatus according to claim 8, wherein said tracking means is movable type optical path alteration means disposed in an optical path between said acousto-optic diffracter and said objective lens.

Claim 17

Dependent Claim 39 words

An apparatus according to claim 14, wherein said optical path alteration means is made of a transparent member, and a position of a light beam transmitted through said transparent member can be altered by turning of said transparent member.

Claim 18

Dependent Claim 34 words

An apparatus according to claim 14, wherein said optical path alteration means is made of a reflective member, and a sense of a light beam can be altered by movement of said reflective member.

Claim 19

Dependent Claim 164 words

An apparatus according to claim 13, wherein said variable frequency oscillator is composed of a quartz oscillator, a first scaler which divides an output frequency of said quartz oscillator, a phase locked loop, and a control circuit which controls said first scaler and a third scaler of said phase locked loop; and said phase locked loop includes a voltage-controlled oscillator which generates a signal of a frequency corresponding to a control voltage, a second scaler which divides the output frequency of said voltage-controlled oscillator, the third scaler which divides a freauency of an output of said second scaler, a phase detector which detects a phase difference between an output of said first scaler and an output of said third scaler and generates the control voltage corresponding to the phase difference, and a low-pass filter which applies the output of said phase detector to said voltage-controlled oscillator after removing high frequency components thereof; said acousto-optic diffracter being driven by the output of said voltage-controlled oscillator.

Claim 20

Dependent Claim 188 words

An apparatus according to claim 13, wherein said variable frequency oscillator is composed of a quartz oscillator, a first scaler which divides an output frequency of said quartz oscillator, a frequency synthesizer which produces a signal of a desired frequency on the basis of an output of said scaler, a phase locked loop, a mixer which mixes an output of a voltage-controlled oscillator and the output of said quartz oscillator, and a band-pass filter which derives a side band component of an output of said mixer; and said phase locked loop includes the voltage-controlled oscillator which generates the signal of a frequency corresponding to a control voltage, a second scaler which divides the output frequency of said voltage-controlled oscillator, a phase detector which detects a phase difference between the output of said frequency synthesizer and an output of said second scaler and generates the control voltage correspoding to the phase difference, and a low-pass filter which applies the output of said phase detector to said voltage-controlled oscillator after removing high frequency components thereof; said acousto-optic diffracter being driven by the signal derived by means of said band-pass filter.

Apparatus for optically writing information

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