| 摘要 |
A pulse width modulation (PWM) optical disk drive calibrates the write and preheat pulse patterns generated by the laser to a particular media and media condition. This is accomplished by either reading information prewritten on the media, which indicates the expected thermal interference, or by directly measuring the thermal interference from a calibration sequence recorded when new media is inserted into the disk drive. The direct measurement of thermal interference is performed by first trial writing a specific calibration sequence of marks and gaps on the media. This calibration sequence, called the E(th) sequence, is then read back and the thermal interference value, E(th), is calculated. The specific write and preheat pulse patterns are then adjusted, as a function of the calculated value of E(th), by selecting new sets of write and preheat pulse patterns. The new sets of write and preheat patterns are selected from a look-up table that correlates the correct pattern sets with the measured value of E(th).
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