EP0342624A2 — Magneto-optical data recording system

Claim 1

Independent Claim 190 words

A magneto-optical data recording system comprising: a magneto-optic recording medium (1) comprising first and second areas (4, 5) alternately provided periodically along a track (2) thereof, the first area comprising at least a clock pit (7) provided beforehand in an optically detectable form and the second area being for recording code data therein; means (27) for applying a magnetic field pulse (32) of a polarity corresponding to code data (31) to be recorded to the recording medium (1); means (25) for locally heating a portion of the recording medium (1) to which the magnetic field pulse is applied; and means (36) for generating a clock (9) of a predetermined frequency synchronous with a reproduced signal (8) corresponding to the clock pit (7), characterized in that the magnetic field pulse applying means (27) applies a magnetic pulse (32) of a polarity corresponding to the code data (31) to be recorded in accordance with the clock, and that the heating means (25) successively heats the recording medium in a pulsating manner at a predetermined frequency synchronous with the clock (9) (Fig. 2(E)) while recording the code data in the second area (5).

Claim 2

Dependent Claim 190 words

A magneto-optical data recording system comprising: a magneto-optic recording medium (1) comprising first and second areas (4, 5) alternately provided periodically along a track (2) thereof, the first area comprising at least a clock pit (7) provided beforehand in an optically detectable form and the second area being for recording code data therein; means (27) for applying a magnetic field pulse (32) of a polarity corresponding to code data (31) to be recorded to the recording medium (1); means (25) for locally heating a portion of the recording medium (1) to which the magnetic field pulse is applied; and means (36) for generating a clock (9) of a predetermined frequency synchronous with a reproduced signal (8) corresponding to the clock pit (7), characterized in that the magnetic field pulse applying means (27) applies a magnetic pulse (32) of a polarity corresponding to the code data (31) to be recorded in accordance with the clock, and that the heating means (25) successively heats the recording medium in a pulsating manner at a predetermined frequency synchronous with the clock (9) (Fig. 2(E)) while recording the code data in the second area (5).

Claim 3

Dependent Claim 62 words

A magneto-optical data recording system as set forth in Claim 1, wherein the magnetic field pulse applying means comprises: a data generator (37) for generating the code data in accordance with the clock (9); and a magnetic coil (27) for changing the polarity of the applied magnetic field in accordance with the value of the code data read from the data generator.

Claim 4

Dependent Claim 98 words

A magneto-optical data recording system as set forth in Claim 1 or 2, wherein the heating means comprises an optical head which comprises an optical head which, in turn, comprises: laser means (23); an optical system (24) for focusing the laser beam from the laser means onto the recording medium (1); and photoelectric conversion means (29) for receiving and converting a reflected beam from the recording medium (1) to an electric signal; wherein the optical head continuously irradiates a low-output laser beam during reproduction, and a high-output laser beam pulse (30) synchronous with the clock (9) during recording.

Claim 5

Dependent Claim 32 words

A magneto-optical data recording system as set forth in Claim 3, wherein the laser means (23) is driven by a laser driver (26) which is controlled in accordance with the clock (9).

Claim 6

Dependent Claim 40 words

A magneto-optical data recording system as set forth in Claim 3 or 4, wherein the magnetic pulse (32) applied by the magnetic field pulse applying means (27) is wider in time width than the laser beam pulse (30) (Fig. 3).

Claim 7

Dependent Claim 37 words

A magneto-optical data recording system as set forth in any one of Claims 3 - 5, further comprising means (38) for adjusting the relation in phase between the magnetic field pulse (32) and the laser pulse (30).

Claim 8

Dependent Claim 42 words

A magneto-optical data recording system as set forth in any one of claims 3 - 6, wherein the energy of the laser pulse (30) is changed in accordance with the code data read from the data generator (37) (Figs. 4A and 4B).

Claim 9

Dependent Claim 62 words

A magneto-optical data recording system as set forth in any one of Claims 1 - 7, wherein the clock means comprises: means (35) for extracting a signal (8) corresponding to the clock pit (7) from the output of the photoelectric conversion means (29); and phase-locked loop means (36) for generating a clock (9) synchronously with the signal extracted by the extracting means.

Claim 10

Independent Claim 143 words

A method of recording magneto-optical data, comprising the steps of: applying a magnetic field pulse (32) of a polarity corresponding to code data to be recorded (31) from magnetic field applying means (27) to a magneto-optic data recording medium (1); and locally heating the portion of the magneto- optical recording medium (1) to which the magnetic field pulse is applied, using heating means (25), to thereby record the code data (31) onto the recording medium, characterized by the steps of: applying a magnetic field pulse (32) of a polarity corresponding to code data to be recorded (31) from the magnetic field pulse applying means (27) along a track (2) of the medium (1) during recording, and continuously heating the medium using the heating means (25) in a pulsating manner at a predetermined frequency synchronous with the code data while overwriting the code data.

Claim 11

Independent Claim 143 words

A method of recording magneto-optical data, comprising the steps of: applying a magnetic field pulse (32) of a polarity corresponding to code data to be recorded (31) from magnetic field applying means (27) to a magneto-optic data recording medium (1); and locally heating the portion of the magneto- optical recording medium (1) to which the magnetic field pulse is applied, using heating means (25), to thereby record the code data (31) onto the recording medium, characterized by the steps of: applying a magnetic field pulse (32) of a polarity corresponding to code data to be recorded (31) from the magnetic field pulse applying means (27) along a track (2) of the medium (1) during recording, and continuously heating the medium using the heating means (25) in a pulsating manner at a predetermined frequency synchronous with the code data while overwriting the code data.

Claim 12

Dependent Claim 57 words

A method of recording magneto-optical data as set forth in Claim 9, wherein the magnetic field pulse applying means used is a magnetic coil (27) driven in accordance with code data (31) read from a data generator (37) for changing the polarity of the applied magnetic field (32) in accordance with the value of the code data.

Claim 13

Dependent Claim 79 words

A method of recording magneto-optical data as set forth in Claim 9 or 10, wherein the heating means used is: an optical head which, in turn, comprises: laser means (23) the drive of which is controlled by a driver (26); an optical system (24) for focusing the laser beam from the laser means onto the recording medium (1); and photoelectric conversion means (29) for receiving and converting the reflected beam from the recording medium (1) to an electric signal.

Claim 14

Independent Claim 63 words

A method of recording magneto-optical data as set forth in any one of Claims 9 - 11, wherein the recording medium comprises first and second areas (4, 5) alternately provided periodically along the track (2), the first area comprising at least a clock pit (7) provided beforehand in an optically detectable form, and the second area being for recording the code data therein.

Claim 15

Dependent Claim 90 words

A method of recording magneto-optical data as set forth in Claim 12, further comprising the steps of: extracting a signal (8) corresponding to the clock pit (7) from the output of the photoelectric conversion means (29) to generate a clock of a predetermined frequency synchronous with the signal; reading the code data from the data generator (37) in accordance with the clock (9); and controlling the driver (26) in accordance with the clock (9) to cause the laser means (23) to emit a laser pulse (30) synchronous with the clock.

Claim 16

Dependent Claim 34 words

A method of recording magneto-optical data as set forth in Claim 13, wherein the magnetic pulse (32) applied by the magnetic field pulse applying means is wider than the laser pulse (30) (Fig. 3).

Claim 17

Dependent Claim 32 words

A method of recording magneto-optical data as set forth in Claim 13 or 14, further comprising the step of adjusting the relation in phase between the magnetic pulse and the laser pulse.

Claim 18

Dependent Claim 50 words

A method of recording a magneto-optical data as set forth in Claim 14 or 15, wherein the code data read from the data generator (37) is delivered to the driver (26) to change the energy of the laser pulse (30) in accordance with the code data (Figs. 4A and 4B).

Magneto-optical data recording system

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