Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
143 words
A method for overwriting information in a magneto-optical memory medium which comprises a substrate (11) having a layer of magneto-optical recording material (13) with a perpendicular magnetising characteristic coated on it, the method including applying a write signal (W) in the form of a pulsed laser beam having a power sufficient to write information into an information-carrying area of the memory medium and applying an erase signal (E) in the form of a laser beam having a power lower than the write signal (W), insufficient to write information into the memory medium but sufficient to erase any information previously written into the information carrying area of the memory medium; characterised in that either the write signal (W) or the erase signal is applied over all of the information carrying area of the memory medium to be overwritten regardless of the previously written information.
Claim 2
Independent Claim
143 words
A method for overwriting information in a magneto-optical memory medium which comprises a substrate (11) having a layer of magneto-optical recording material (13) with a perpendicular magnetising characteristic coated on it, the method including applying a write signal (W) in the form of a pulsed laser beam having a power sufficient to write information into an information-carrying area of the memory medium and applying an erase signal (E) in the form of a laser beam having a power lower than the write signal (W), insufficient to write information into the memory medium but sufficient to erase any information previously written into the information carrying area of the memory medium; characterised in that either the write signal (W) or the erase signal is applied over all of the information carrying area of the memory medium to be overwritten regardless of the previously written information.
Claim 3
Dependent Claim
42 words
A method according to claim 1, wherein a single laser beam head (21) applies either the writing signal (W) or the erase signal (E) selectively in accordance with the information to be written onto the information carrying area of the memory medium.
Claim 4
Dependent Claim
56 words
A method according to claim 1, wherein, initially the erase signal is applied to the information area of the memory medium to be overwritten to erase information previously written on it, and then the write signal is selectively applied to the information area to write the required information into the information area of the memory medium.
Claim 5
Independent Claim
20 words
A method according to any one of the preceding claims, wherein the information is "0" and "1" binary signal information.
Claim 6
Independent Claim
25 words
A method according to any one of the preceding claims, wherein writing and erasing signals are applied in the presence of an auxiliary magnetic field.
Claim 7
Independent Claim
22 words
A method according to any one of the preceding claims, wherein the magneto-optical memory medium is in the form of a disk.
Claim 8
Independent Claim
21 words
A method according to any one of the preceding claims, wherein the erase signal is provided by a continuous laser beam.
Claim 9
Independent Claim
50 words
A method according to any one of claims 1 to 6, wherein erase signal (E) is provided by a repetitively pulsed laser beam having a higher repetition frequency and each pulse of which has a pulse width narrower than that of the pulsed laser beam forming the writing signal (W).
Claim 10
Dependent Claim
34 words
A method according to claim 8, wherein the frequency of the erase signal (E) is 3 times or more higher than a maximum frequency of the pulsed laser beam forming the writing signals (W).
Claim 11
Independent Claim
31 words
A method according to any one of the preceding claims, wherein the intensity of the laser beam providing the erase signal (E) is lower than that providing the writing signal (W).
Claim 12
Dependent Claim
30 words
A method according to claim 8 or 9, wherein the intensity of the laser beam providing the erase signal (E) is the same as that providing the writing signal (W).