Over-write capable magnetooptical recording method with widened power margin, and magnetooptical recording apparatus used in this method

Claim 2

An over-write magnetooptical recording method having improved ease of discrimination of data, comprising the steps of: preparing an over-write multi-layered magnetooptical recording medium, which consists of at least two layers including a memory layer and a writing layer, and in which the memory layer and the writing layers are exchange-coupled to each other, a direction of magnetization of the writing layer can be aligned in a predetermined direction at room temperature without changing a direction of magnetization of the memory layer, and the direction of the magnetization of the writing layer is already aligned in the predetermined direction; rotating said medium; radiating a laser beam onto said medium; pulse-modulating an intensity of the laser beam between a high level P H and a low level P L according to binary coded information to be recorded; and applying a bias field to an irradiation position of the laser beam, wherein when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and the intensity is returned to the low level P L after the mark formation.

Claim 3

An over-write magnetooptical recording method having improved ease of discrimination of data, comprising the steps of: preparing an over-write multi-layered magnetooptical recording medium, which consists of at least two layers including a memory layer and a writing layer, and in which the memory layer and the writing layers are exchange-coupled to each other, a direction of magnetization of the writing layer can be aligned in a predetermined direction at room temperature without changing a direction of magnetization of the memory layer, and the direction of the magnetization of the writing layer is already aligned in the predetermined direction; rotating said medium; irradiating a laser beam onto said medium; pulse-modulating an intensity of the laser beam between a high level P H and a low level P L according to binary coded information to be recorded; and applying a bias field to an irradiation position of the laser beam, wherein when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, the intensity is temporarily decreased below the limit value P Lmin and is returned to the low level P L .

Claim 4

An over-write magnetooptical recording method having improved ease of discrimination of data, comprising the steps of: preparing an over-write multi-layered magnetooptical recording medium, which consists of at least two layers including a memory layer and a writing layer, and in which the memory layer and the writing layers are exchange-coupled to each other, a direction of magnetization of the writing layer can be aligned in a predetermined direction at room temperature without changing a direction of magnetization of the memory layer, and the direction of the magnetization of the writing layer is already aligned in the predetermined direction; rotating said medium; irradiating a laser beam onto said medium; pulse-modulating an intensity of the laser beam between a high level P H and a low level P L according to binary coded information to be recorded; and applying a bias field to an irradiation position of the laser beam, wherein when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, the intensity is temporarily decreased below the limit value P Lmin and is returned to the low level P L .

Claim 5

An over-write magnetooptical recording method having improved ease of discrimination of data, comprising the steps of: preparing an over-writing capable multi-layered magnetooptical recording medium, which consists of at least two layers including a memory layer and a writing layer, and in which the memory layer and the writing layers are exchange-coupled to each other, a direction of magnetization of the writing layer can be aligned in a predetermined direction at room temperature without changing a direction of magnetization of the memory layer, and the direction of the magnetization of the writing layer is already aligned in the predetermined direction; rotating said medium; irradiating a laser beam onto said medium; pulse-modulating an intensity of the laser beam between a high level P H and a low level P L according to binary coded information to be recorded; and applying a bias field to an irradiation position of the laser beam, wherein when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, when the intensity is decreased to the low level P L , the intensity is temporarily decreased below the limit value P Lmin and is then returned to the low level P L .

Claim 6

An over-write magnetooptical recording method having improved ease of discrimination of data, comprising the steps of: preparing an over-writing capable multi-layered magnetooptical recording medium, which consists of at least two layers including a memory layer and a writing layer, and in which the memory layer and the writing layers are exchange-coupled to each other, a direction of magnetization of the writing layer can be aligned in a predetermined direction at room temperature without changing a direction of magnetization of the memory layer, and the direction of the magnetization of the writing layer is already aligned in the predetermined direction; rotating said medium; irradiating a laser beam onto said medium; pulse-modulating an intensity of the laser beam between a high level P H and a low level P L according to binary coded information to be recorded; and applying a bias field to an irradiation position of the laser beam, wherein when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, when the intensity is decreased to the low level P L , the intensity is temporarily decreased below the limit value P Lmin and is then returned to the low level P L .

Claim 7

An over-write magnetooptical recording apparatus comprising: rotating means for rotating a magnetooptical recording medium; a laser beam light source; a light source drive circuit for pulse-modulating an intensity of a laser beam between a high level P H and a low level P L according to binary coded information to be recorded; bias field applying means; and a pulse waveform shaping circuit, in which when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and the intensity is returned to the low level P L after the mark formation.

Claim 8

An over-write magnetooptical recording apparatus comprising: rotating means for rotating a magnetooptical recording medium; a laser beam light source; a light source drive circuit for pulse-modulating an intensity of a laser beam between a high level P H and a low level P L according to binary coded information to be recorded; bias field applying means; and a pulse waveform shaping circuit, in which when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and the intensity is returned to the low level P L after the mark formation.

Claim 9

An over-write capable magnetooptical recording apparatus comprising: rotating means for rotating a magnetooptical recording medium; a laser beam light source; a light source drive circuit for pulse-modulating an intensity of a laser beam between a high level P H and a low level P L according to binary coded information to be recorded; bias field applying means; and a pulse waveform shaping circuit, in which when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L capable of erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, the intensity is temporarily decreased below the limit value P Lmin and is returned to the low level P L .

Claim 10

An over-write capable magnetooptical recording apparatus comprising: rotating means for rotating a magnetooptical recording medium; a laser beam light source; a light source drive circuit for pulse-modulating an intensity of a laser beam between a high level P H and a low level P L according to binary coded information to be recorded; bias field applying means; and a pulse waveform shaping circuit, in which when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L capable of erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, the intensity is temporarily decreased below the limit value P Lmin and is returned to the low level P L .

Claim 11

An over-write magnetooptical recording apparatus comprising: rotating means for rotating a magnetooptical recording medium; a laser beam light source; a light source drive circuit for pulse-modulating an intensity of a laser beam between a high level P H and a low level P L according to binary coded information to be recorded; bias field applying means; and a pulse waveform shaping circuit, in which when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, when the intensity is decreased to the low level P L , the intensity is temporarily decreased below the limit value P Lmin and is then returned to the low level P L .

Claim 12

An over-write magnetooptical recording apparatus comprising: rotating means for rotating a magnetooptical recording medium; a laser beam light source; a light source drive circuit for pulse-modulating an intensity of a laser beam between a high level P H and a low level P L according to binary coded information to be recorded; bias field applying means; and a pulse waveform shaping circuit, in which when a mark previously formed by the beam at the high level P H is defined as a pre-recorded mark, and a minimum low level P L for erasing the pre-recorded mark upon irradiation of a DC-ON laser beam is defined as a limit value P Lmin , when the intensity of the laser beam is increased from the low level P L to the high level P H , the intensity is temporarily decreased below the limit value P Lmin and is then increased to the high level the intensity of the laser beam is decreased to continue the mark formation after mark formation based on the high level P H is started, and after the mark formation, when the intensity is decreased to the low level P L , the intensity is temporarily decreased below the limit value P Lmin and is then returned to the low level P L .