Methods of determining the optimal erase and write power, and recording apparatus with devices for said methods
AssigneeKoninklijke Philips Electronics N.V.
InventorsGuo-Fu Zhou, Roel Van Woudenberg, Johannes H.M. Spruit
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Abstract
The application relates to methods and devices for determining the optimal erase (17) and write powers for erasing and writing information on an optical record carrier (85). These optimal powers are determined from two powers, Pmin (15) and Pmax (16), found at specific points, (22) and (24), in a curve (10) where the normalized reflected power (12) is plotted versus the test power (11).
Claims17
A method of determining the optical erase power for erasing marks provided in an optical record carrier of the type in which marks are provided by locally heating the record carrier with radiation pulses having a sufficiently high power so as to cause changes in optical properties of the record carrier, which changes become manifest by a reduced reflection of the radiation pulses, characterized in that the method comprises
- a preparatory step of providing marks on the record carrier by locally heating the record carrier with radiation pulses having a first power, followed by
- a first measuring step of determining a second power (Pmin) of the radiation pulses, at which power the optical properties of the record carrier at the location of the marks provided in the preparatory step do not substantially change when the record carrier is irradiated at a power which is lower than said second power, and the optical properties of the record carrier at the location of the provided marks change to such an extent that the normalized reflected power increases, when the record carrier is irradiated at a power which is higher than said second power, and
- a second measuring step of determining a third power (Pmax) of the radiation pulses, at which power the optical properties of the record carrier change when the record carrier is irradiated at said third power at the location of the marks provided in the preparatory step, such that the normalized reflected power becomes maximal, followed by
- a comparison step of determining the optimal erase power (PEO) from the equation
- 5 P EO = β · ( P min + P max ) α
- in which α is a constant known in advance and β is a variable which is dependent on properties of the record carrier.
A method of determining the optical write power for providing marks in an optical record carrier, which marks are provided by locally heating the record carrier with radiation pulses having a sufficiently high power so as to cause changes in optical properties of the record carrier, which changes become manifest by a reduced reflection of the radiation pulses, characterized in that the method comprises
- a preparatory step of providing marks on the record carrier by locally heating the record carrier with radiation pulses having a first power, followed by
- a first measuring step of determining a second power (Pmin) of the radiation pulses, at which power the optical properties of the record carrier at the location of the marks provided in the preparatory step do not substantially change when the record carrier is irradiated at a power which is lower than said second power, and the optical properties of the record carrier at the location of the provided marks change to such an extent that the normalized reflected power increases, when the record carrier is irradiated at a power which is higher than said second power, and
- a second measuring step of determining a third power (Pmax) of the radiation pulses, at which power the optical properties of the record carrier change when the record carrier is irradiated at said third power at the location of the marks provided in the preparatory step, such that the normalized reflected power becomes maximal, followed by
- a comparison step of determining the optimal write power (PWO) from the equation
- 6 P WO = δ · β · ( P min + P max ) α
- in which α is a constant known in advance and β and δ are variables which are dependent on properties of the record carrier.
An optical record carrier for use in one of the methods as claimed 1 or 12, inscribable by a radiation beam, containing an area comprising information about properties of the optical record carrier, characterized in that the area comprising information about properties of the record carrier comprises a value for the factor β used in the comparison stage of the method.
A recording apparatus comprising a calibration device for determining the optimal erase power required for erasing marks provided in an optical record carrier of the type in which marks are provided by locally heating the record carrier with radiation pulses having a sufficiently high power so as to cause changes in optical properties of the record carrier, which changes become manifest by a reduced reflection of the radiation pulses, characterized in that the calibration device is adapted
- to provide marks on the record carrier by locally heating the record carrier with radiation pulses having a first power, and
- to determine a second power (Pmin) of the radiation pulses, at which power the optical properties of the record carrier at the location of the provided marks do not substantially change when the record carrier is irradiated at a power which is lower than said second power, and the optical properties of the record carrier at the location of the provided marks change to such an extent that the normalized reflected power increases, when the record carrier is irradiated at a power which is higher than said second power, and
- to determine a third power (Pmax) of the radiation pulses, at which power the optical properties of the record carrier change when the record carrier is irradiated at said third power at the location of the provided marks, such that the normalized reflected power becomes maximal, and
- to determine the optimal erase power (PEO) from the equation
- 7 P EO = β · ( P min + P max ) α
- in which α is a constant known in advance and β is a variable which is dependent on properties of the record carrier.
A recording apparatus comprising a calibration device for determining the optimal write power required for providing marks in an optical record carrier, which marks are provided by locally heating the record carrier with radiation pulses having a sufficiently high power so as to cause changes in optical properties of the record carrier, which changes become manifest by a reduced reflection of the radiation pulses, characterized in that the calibration device is adapted
- to provide marks on the record carrier by locally heating the record carrier with radiation pulses having a first power, and
- to determine a second power (Pmin) of the radiation pulses, at which power the optical properties of the record carrier at the location of the provided marks do not substantially change when the record carrier is irradiated at a power which is lower than said second power, and the optical properties of the record carrier at the location of the provided marks change to such an extent that the normalized reflected power increases, when the record carrier is irradiated at a power which is higher than said second power, and
- to determine a third power (Pmax) of the radiation pulses, at which power the optical properties of the record carrier change when the record carrier is irradiated at said third power at the location of the provided marks, such that the normalized reflected power becomes maximal, and
- to determine the optimal write power (PWO) from the equation
- 8 P WO = δ · β · ( P min + P max ) α
- in which α is a constant known in advance and β and δ are variables which are dependent on properties of the record carrier.
Dependencies are inferred from the claim text.