Abstract: A system for determining a cleanliness of a lens of an optical disc drive. The system includes a controller configured to control movement of the lens of the optical disc drive between a first position and a second position relative to the optical disc. The first position is located a first distance from an outer surface of the optical disc and corresponds to a position causing the lens to focus light on a data layer of the optical disc. The second position is located a second distance, different than the first distance, from the outer surface and corresponds to a position causing the lens to focus light on the outer surface. The controller is further configured to receive a measurement of light reflected by the optical disc while the lens is in the second position and determine the cleanliness of the lens based on the measurement of the light.

Abstract: An apparatus and a method for reducing an offset error in a position of an objective lens of an optical disk reader by using a single beam push-pull signal. The apparatus includes a radial actuator that is configured to control the position of the objective lens. A controller that receives a push-pull signal that corresponds to the offset error of the objective lens and estimates the offset based on the push-pull signal. A sine generator generates a sine wave based on the estimated offset and further generates a feedback signal based on the sine wave to drive the radial actuator to reduce the offset error in the position of the objective lens. The apparatus also includes a data detector that is utilized to change the tracking method of the optical disk reader to a differential phase detection method upon detecting data in a data spire of the optical disk.

Abstract: Apparatus having corresponding methods comprise: a light source configured to produce light; a lens configured to focus the light on an optical disc; a photo detector configured to obtain a measurement of the light reflected by the optical disc; and a controller configured to determine a cleanliness of the lens based on the measurement of the light reflected by the optical disc responsive to the lens focusing the light on a surface of the optical disc.

Abstract: New and useful methods and systems for reading optical discs, such as multi-layer Blu-ray discs are disclosed. For example, in an embodiment a device for reading two-layered optical discs includes a laser diode capable of emitting light, a set of optics including a fixed collimator, the set of optics providing a numerical aperture (NA) of substantially less than 0.85, and a detector for detecting laser light focused on a two-layer optical disc to produce a stream of detected bits.

Abstract: New and useful methods and systems for reading optical discs, such as multi-layer Blu-ray discs are disclosed. For example, in an embodiment a device for reading two-layered optical discs includes a laser diode capable of emitting light, a set of optics including a fixed collimator, the set of optics providing a numerical aperture (NA) of substantially less than 0.85, and a detector for detecting laser light focused on a two-layer optical disc to produce a stream of detected bits.

Abstract: The invention relates to disc drive mechanism (100) which comprises an actuator (113) controlling a radial movement of a lens (109). An actuator controller (115) generates an actuator control signal which is fed to the actuator (113). An activation time processor (125) determines an amplitude variation characteristic of the actuator control signal. Specifically, the activation time processor (125) determines how the amplitude varies as a function of the rotation angle. The activation time processor (125) determines an activation time for a position change actuator signal component which causes the actuator (113) to move the lens (109) to jump to a different track. The position change actuator signal component is added to the actuator control signal in the actuator controller (115) thereby generating a combined actuator control signal which both tracks the disc and effectuates a jump. The activation time is selected such that the dynamic range of the actuator control signal is reduced.

Abstract: An optimizing of a gain in a servo control loop (21) of an optical drive is performed for the control of an actuator for focusing and tracking a laser beam (10) for reading or writing data from/to optical discs (1), wherein the actuator is controlled by a servo controller (20) in the control loop (21), by means of an algorithm performing the steps: predetermining a reference oscillation level for the servo control loop (21), iteratively checking if a power output from the control loop (21) used as an dissipation level value is less than the reference oscillation level, increasing the gain in the servo control loop in each iteration step until said dissipation level value is equal to or greater than the reference oscillation level and then decreasing the gain in the control loop by a margin value.

Abstract: A method and apparatus for a feedback loop (30) used with a servo controller (14) to control an actuator (13, 17) of an optical disc drive. The gain (18) in the feedback loop (30) determines the bandwidth of the actuator (13, 17) in accordance with predetermined parameters for predetermined intervals. High rotational disk speeds, especially during writing, necessitate that the actuator servo controller feedback loop have a high loop gain and can become critical. Higher gains will cause oscillations in the loop. Loop gain spread from sources such as detector sensitivity differences on recorded and non recorded areas, is controlled by setting the control gain at an initial value lower than the maximal value in order to avoid oscillations. The control gain is then adjusted to a maximum value by means of an AGC mechanism. This AGC mechanism is activated for short periods of times to adjust the gain.

Abstract: A method and apparatus that compensates for power variations occurring in a beam (11) of reflected light from a laser (10) within optical disc recording devices. Signal multiplication techniques are applied to signals indicative of light reflected from the optical disc. The signal multiplication conditions signal indicative of the reflected light by selecting a gain factor from one of a plurality of possible constants. The constant selected by the gain factor is dependent on the determined state of the device. Factors used in determining the gain factor include of the position of the light spot from the laser is currently passing over written track or passing over unwritten tracks, and whether the laser is currently in a read mode or a write mode. These constants as determined create a gain factor corrected signal that is independent of the state of the optical pick-up.

Abstract: The present invention relates to a method and to a reproducing apparatus for performing an actuator jump operation so as to move a pick-up means (1) from one track to another track (the target track) over a number of tracks. A braking signal for stopping the movement of the pick-up means (1) is composed of a first component measured during a preceding velocity control period and used for maintaining the pick-up means (1) at a constant velocity and a second component for stopping the movement of the pick-up means (1) at the target track. The duration of an active brake period is the same for each braking action and the calculation of parameters for controlling a braking signal is simplified.