Writable optical drive with dynamically variable linear velocity to prevent buffer under-run

A method of writing data to an optical disc comprising:

• receiving data to be written to the optical disc from a host computer;
• storing data to be written to the optical disc in a memory buffer;
• writing data from the memory buffer to the optical disc in a continuous write sequence at a substantially constant linear density;
• detecting a condition that may result in a buffer under-run event;
• and
• changing a linear velocity of the optical disc in response to the condition while writing to the optical disc to reduce a likelihood of the buffer under-run event occurring.

A write power control circuit adapted to dynamically vary a write power of a laser used to write data on an optical disc while writing to the optical disc and changing a linear velocity of the optical disc, the write power control circuit comprising:

• an amplifier, a control input of the amplifier controlling an output of the amplifier, the output of the amplifier affecting the write power of the laser;
• a sampling circuit, the sampling circuit measuring a characteristic of a mark made by the laser on the optical disc at a discrete time;
• and
• a feedback circuit, the feedback circuit receiving the characteristic of the mark from the sampling circuit, the feedback circuit comparing the characteristic of the mark to a target characteristic, the feedback circuit adapted to maintain the write power of the laser by manipulating the control input of the amplifier to align a characteristic of marks made by the laser to the target characteristic, the feedback circuit further configured to provide a sufficient power adjustment range to accommodate a change in the linear velocity of the optical disc.

A controller for an optical drive, the optical drive adapted to write data on an optical disc and change a linear velocity while writing to the optical drive to reduce a likelihood of a buffer under-run condition, the controller comprising:

• a first circuit adapted to monitor a write speed;
• a second circuit adapted to monitor a linear velocity of the optical disc;
• and
• a third circuit adapted to change the linear velocity of the optical disc and maintain the write speed and the linear velocity such that the write speed and the linear velocity maintain a relationship while the linear velocity changes.

An optical drive system, the optical drive system adapted to write data on an optical disc and change a linear velocity while writing to the optical drive, the optical drive system comprising:

• a control circuit adapted to receive data to be written to the optical disc from a host computer;
• a buffer adapted to store data received by the control circuit;
• a writing circuit adapted to retrieve data from the buffer, the writing circuit further adapted to write the data from the buffer as a series of pulses recorded on the optical disc in a continuous write sequence at a substantially constant linear density;
• a detection sensor adapted to detect a condition that may result in a buffer under-run event;
• and
• a writing speed circuit, the writing speed circuit adapted to control a rate at which the writing circuit records to the optical disc, the writing circuit further adapted to decrease a linear velocity of the optical disc in response to the detected condition while writing to the optical disc to reduce a likelihood of an occurrence of the buffer under-run event.