Koninklijke Philips Corporation N.v.

U.S. Philips Corporation

Intrinsic Id B.v.

Koninklijke Philips Electronics N.v.

Genkey Netherlands B.v.

Priv Id B.v.

Antonius H M Akkermans

Pim Theo Tuyls

Willem Gerard Ophey

Boris Skoric

Cornelius Antonius Hezemans

Peter Coops

Bartholomeus Johannes Van Rijnsoever

Jozef P H Benschop

George A L Leenknegt

Martinus P M Bierhoff

Anthonius L J Dekker

Theodorus A E Langenhuizen

Robert P Koster

Carsten Heinks

Raymond N J Veldhuis

Chun Chen

Jasper Goseling

Vincent Van Der Leest

A device for reading and/or writing information from an optical carrier, the device comprising an imager for imaging a radiation beam into scanning spot to scan the carrier, and a detector for generating a read signal indicative of the intensity of the radiation reflected from the carrier. The device has an information transfer mode, wherein the scanning spot is moved in a first direction. The device has a displacement mode, wherein the scanning spot is moved in a second direction transverse to the first direction. The device includes a controller for controlling the imager in response to a measurement signal indicative of the degree of focusing of the radiation beam. The controller samples and holds the measurement signal in response to a sample signal causing the measurement signal to be sampled when the intensity is comparatively high thus reducing radial-to-vertical crosstalk.

Device for reading and/or writing information from/onto an optical information carrier

An apparatus for driving a record carrier according to the invention comprises a transducer for generating a read signal in response to patterns recorded at the record carrier and displacement means for displacing the transducer and the record carrier with respect to each other. Out of the read signal an auxiliary signal having a relatively low frequency content is generated. The apparatus comprises binary signal generating means for generating a binary signal out of the auxiliary signal including first hold means for generating a first hold signal, second hold means for generating a second hold signal, signal combination means for generating a slicing signal out of the first hold signal and the second hold signal, and comparing means for comparing the auxiliary signal with the slicing signal and outputting a binary output signal. The first hold means are adapted for temporarily maintaining the first hold signal at a value substantially corresponding to a top value of the auxiliary signal. The first hold means are further adapted for temporarily maintaining the value of the first hold signal at a value substantially corresponding to a bottom value of the auxiliary signal augmented by an addition value. The second hold means are adapted for temporarily maintaining the second hold signal substantially at a value corresponding to a bottom value of the auxiliary signal. The second hold means are further adapted for temporarily maintaining the value of the second hold signal at a value corresponding to a top value of the auxiliary signal diminished by a subtraction value.

Apparatus for driving a record carrier

A device according to the invention for scanning a rotating information carrier ( ) comprises a transducer ( ) and controller ( ) for controlling a scanning parameter of the transducer ( ), such as the radial position and the setting of a focus. The controller comprise difference signal generator ( ) for generating a difference signal (RE) which is indicative of a difference between a current value and a desired value of the scanning parameter, and correction signal generator ( ) for generating a correction signal (S ) in response to the difference signal. The correction signal generator ( ) comprise a delay loop ( ) having first in first out memory ( ) for generating a delayed signal (S ) and feedback filter ( ) for filtering the delayed signal (S ). The device comprises rotation speed detector ( ) for generating a clock signal (CL) having a frequency which is indicative of the rotation speed of the information carrier ( ), the delay in the memory ( ) being proportional to a period of the clock signal.

Device for scanning a rotating information carrier

A device for optically scanning an information plane having tracks. Radiation is supplied by a radiation source focused on the information plane by an objective system. The beam reflected by the information plane is incident on a dividing element, for example a grating which divides the beam into two halves along a dividing line. Two sub-gratings at both sides of the dividing line each form a detection beam from one half of the beam, which detection beams are detected each by a detector. A focus error signal is generated from the detector signals by forming a difference signal of the two detector signals and dividing this difference signal by the sum signal of the two detector signals. The focus error signal is relatively insensitive to the position accuracy of the detectors with respect to the detection beams.

Device for optically scanning information tracks on a plane using two subbeams

Apparatus for reading and/or writing onto an information carrier includes the positioning system. The positioning system includes a drive member for moving a second part with respect to a first part and a fine-positioning member for moving a third part with respect to the second part. The positioning member also includes control means for continuously controlling the drive member in response to the orientation signal. The control means include control signal generating means for generating a control signal from the orientation signal. The control means further include a sensor for generating an auxiliary signal which is an indication for a current consumed by the drive member, and signal combination means for generating a drive voltage for the drive member in response to the control signal and the auxiliary signal.

Positioning system and apparatus including the positioning system

An optical beam (,) in a scanning device is focused on an information layer (,) of a multi-layer optical record carrier. A focus control circuit (,) keeps the focal point (,) of the beam on the information layer. When the focal point jumps to another information layer, the focus control circuit does not monitor the so-called central aperture signal in order not to depend on the presence of information in the information layers. During the jump the characteristics of the feedback loop of the focus control unit are modified to avoid instabilities in the movement of the focal point during the jump. When the focal point is captured on the designated information layer, the characteristics of the feedback loop are restored.

Optical scanning apparatus for a multi-layer record carrier, including a focus control circuit

A control system in accordance with the invention comprises error signal generating means for generating an error signal in response to a reference signal and a first and a second position signal. The reference signal is a measure of the desired value of a position of a first part of a drive system with respect to a second part of the drive system. The position signals are a measure of the actual value of said position. The error signal is a measure of the difference between the desired value and the actual value of the position. The control system further comprises energizing means for energizing a motor which is to be controlled by the control system in dependence on the error signal. The control system of the invention is characterized in that the error signal generating means are adapted to generate weighting factors from the reference signal, for weighting the position signals with the weighting factors and determining a sum of the weighted position signals. The control system can be used in a recording/playback device for positioning a read/write head.

Control system, driving system and control method, apparatus including the driving system

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Eindhoven, Netherlands

Antonius H M Akkermans