Optical disc apparatus switching focus point between layers
View Patent ↗A focus jump technique enables focus control on recording layers of a disc in such a manner that its effect is not absorbed by disturbance or a variation in the movement speed of an objective lens. The technique involves monitoring level of a focus error signal and rejecting noise from the error signal. A speed sensor detects movement speed of an objective lens; and a speed control circuit generates a voltage for controlling the objective lens, based on the detected movement speed. Movement speed of the objective lens is detected during focus jump, a corresponding lens drive signal is generated, and an end position is determined from behavior of the error signal immediately before the end of the jump. A focus control is pulled, from a focus point corresponding to one recording layer, into a focus point corresponding to another recording layer forcibly in a stable manner.
1. An optical disc recording method for real-time recording of broadcast digital data in an optical disc having a first recording layer and a second recording layer, the method comprising steps of:
when a focus servo is in a locked state, recording digital data in the first recording layer with a laser light set for recording power;
during the recording of the digital data, when a recording position for a next recording digital data bridges from the first recording layer to the second recording layer, switching the laser light to a power which is lower than the recording power, and when a focus servo is in an unlocked state, performing an interlayer jump from the first recording layer to the second recording layer with a laser light set for the power which is lower than the recording power,
when the interlayer jump from the first recording layer to the second recording layer has failed, performing a servo recovery processing, and
when the interlayer jump from the first recording layer to the second recording layer has succeeded, detecting the recording position for digital data recording in the second recording layer, switching the laser light to recording power when the focus servo is in a locked state, and recording digital data in the second recording layer.
2. An recording apparatus for mounting an optical disk and for real-time recording of broadcast digital data on the optical disc having a first recording layer and a second recording layer, the apparatus comprising:
a laser which radiates laser light;
an objective lens which collects the laser light and directs the collected laser light to the first and second recording layers of the optical disc;
an actuator which moves the objective lens;
a focus control circuit which outputs a focus control signal for the actuator; and
a laser power control circuit which controls the output of the laser, wherein:
when a focus servo is in a locked state, the laser power control circuit controls the output of the laser to record digital data in the first recording layer with a laser light set for recording power,
during recording the digital data, when a recording position for next recording digital data bridges from the first recording layer to the second recording layer, the laser power control circuit switches the laser light to a second power which is lower than the recording power, and when a focus servo is in an unlocked state, an interlayer jump is performed from the first recording layer to the second recording layer with a laser light set for the power which is lower than the recording power,
when the interlayer jump from the first recording layer to the second recording layer has failed, a servo recovery processing is performed, and
when the interlayer jump from the first recording layer to the second recording layer has succeeded, the recording position for digital data recording in the second recording layer is detected, the laser power control circuit switches the laser light to recording power when the focus servo is in a locked state, and digital data in the second recording layer is recorded.