Method for recording, reproducing and erasing information and thin film for recording information

A method for recording, reproducing and erasing information by using an information recording film having a state which changes upon irradiation by a single energy beam from a single energy source and forming a single energy spot, comprising the steps of:

• setting first, second and third levels of power of the energy beam to be irradiated onto said information recording film;
• and
• allocating said first, second and third levels of power to reproducing, erasing and recording, respectively;
• the first level for the reproducing being a low power level at which no recording or erasing is effected even when the energy beam is continuously irradiated on a travelling recording film with the first level;
• the second level for the erasing being a higher power level than the first level;
• and
• the third level for the recording apparatus alternately with the second level in accordance with an information signal, the third level being applied to the second level so as to be one of added thereto and subtracted therefrom, the third level varying timewise in accordance with the information signal;
• wherein said power levels include a record power level higher than a reproduce power level and an erase power level at least one of higher and lower than the record power level, and laser power of a laser providing the energy beam is pulsively varied from the reproduce power level to the erase power level, from the erase power level to the record power level, and from the record power level to the erase power level in order to rewrite the information, and among the power level variations, two power level variations including from the erase power level to the record power level, and from the record power level to the erase power level are repeated;
• and
• wherein when the power level is at least one of lowered from the erase power level to the record power level, lowered beyond the record power level and then returned to the record power level, and raised from the record power level to the erase power level, raised beyond the erase power level within a difference between the erase power level and the record power level and then returned to the erase power level.

A method for recording, reproducing and erasing information by using an information recording film having a state which changes upon irradiation by a single energy beam from a single energy source and forming a single energy spot, comprising the steps of:

• setting first, second and third levels of power of the energy beam to be irradiated onto said information recording film;
• and
• allocating said first, second and third levels of power to reproducing, erasing and recording, respectively;
• the first level for the reproducing being a low power level at which no recording or erasing is effected even when the energy beam is continuously irradiated on a travelling recording film with the first level;
• the second level for the erasing being a higher power level than the first level;
• and
• the third level for the recording apparatus alternately with the second level in accordance with an information signal, the third level being applied to the second level so as to be one of added thereto and subtracted therefrom, the third level varying timewise in accordance with the information signal;
• wherein a comparator level is set between two levels in the reproduced signal corresponding to two power levels to shape a waveform;
• and
• wherein the comparator level is set close to a reproduce voltage of the less crystallized state of two reproduce voltages.

A method for recording, reproducing and erasing information by using an information recording film having a state which changes upon irradiation by a single energy beam from a single energy source and forming a single energy spot, comprising the steps of:

• setting first, second and third levels of power of the energy beam to be irradiated onto said information recording film;
• and
• alternating said first, second and third levels of power to reproducing, erasing and recording, respectively;
• the first level for the reproducing being a low power level at which no recording or erasing is effected even when the energy beam is continuously irradiated on a travelling recording film with the first level;
• the second level for the erasing being a higher power level than the first level;
• and
• the third level for the recording apparatus alternately with the second level in accordance with an information signal, the third level being applied to the second level so as to be one of added thereto and subtracted therefrom, the third level varying timewise in accordance with the information signal;
• wherein at least the second and third power levels include at least three or more power levels, and the at least three power levels are used to effect multi-level recording.

A method for recording, reproducing and erasing information by using an information recording film having a state which changes upon irradiation by a single energy beam from a single energy source and forming a single energy spot, comprising the steps of:

• setting first, second and third levels of power of the energy beam to be irradiated onto said information recording film;
• and
• allocating said first, second and third levels of power to reproducing, erasing and recording, respectively;
• the first level for the reproducing being a low power level at which no recording or erasing is effected even when the energy beam is continuously irradiated on a travelling recording film with the first level;
• the second level for the erasing being a higher power level than the first level;
• and
• the third level for the recording apparatus alternately with the second level in accordance with an information signal, the third level being applied to the second level so as to be one of added thereto and subtracted therefrom, the third level varying timewise in accordance with the information signal;
• wherein an irradiation time period of the energy beam of the second level is longer than an irradiation time period of the energy beam of the third level when the third level is higher than the second level.

A method for recording, reproducing and erasing information by varying power level between three power levels of a low, an intermediate and a high level of a single energy beam from a single energy source and forming a single energy spot which is irradiated on a recording medium;

• and auto-focusing and tracking are carried out at least at the low power level and rewriting of the information is carried out while said single energy spot of said energy beam once passes across the recording medium, comprising the steps of:
• raising at least the intermediate power level among the three power levels when the recording medium is a rewritable recording medium;
• and
• lowering at least the intermediate power level among the three power levels when the recording medium is a write-once recording medium which allows recording only once;
• thereby enabling use of one apparatus to update recording by overwriting on the rewritable recording medium and to reproduce, and to record and reproduce on and from the write-once recording medium.