Abstract: The invention relates to an information carrier, and a system for positioning such an information carrier in an apparatus. This system comprises an optical element (102) for generating a periodic array of light spots (103) intended to be applied to an information carrier (101), said information carrier (101) comprising a first periodic structure (108) intended to interfere with said periodic array of light spots (103) for generating a first Moiré pattern, and a second periodic structure (109) intended to interfere with said periodic array of light spots (103) for generating a second Moiré pattern, analysis means for deriving from said first and second Moiré patterns, the angle value (S) between said periodic array of light spots (103) and said information carrier (101), and actuation means (AC1-AC2-AC3) for adjusting the angular position of said information carrier (101) with respect to said array of light spots (103), from control signals (114) derived based on said angle value (S).

Abstract: The invention relates to an information carrier (101) intended to be read and/or written by a periodic array of light spots, said information carrier (101) comprising a data area (105) defined by a set of elementary data areas, a first periodic structure (108) intended to interfere with said periodic array of light spots for generating a first moiré pattern, a second periodic structure (109) intended to interfere with said periodic array of light spots for generating a second moiré pattern, said second periodic structure (109) being arranged perpendicularly to said first periodic structure (108). The invention also relates to an apparatus for reading and/or writing said information carrier (101).

Abstract: The invention relates to a system for reading data stored on an information carrier (201), said system comprising: an optical element (202) for generating an array of light spots (203) from an input light beam (204), said array of light spots (203) being intended to scan said information carrier (201), a detector (205) for detecting said data from an array of output light beams generated by said information carrier (201) in response of said array of light spots (203).

Abstract: A disk drive comprising a tray (TR) for receiving a disk, the tray (TR) being supported for movement between a first position within a casing (CS) of the disk drive and a second position projecting from the casing (CS), an electric motor for moving the tray (TR) between the first and second positions, and regulation means for regulating an electric current through the motor for regulating the rotation of the motor. The regulation means comprises detection means for detecting a back-electromotive voltage produced during rotation of the motor for deriving position information of the tray (TR) with respect to the first and second positions.

Abstract: The invention generally relates to the field of repetitive controllers for suppressing periodic signals with half-wave symmetry and, more specifically, to a repetitive controller having the form of a memory loop fed with a periodic signal of period NT and in which the memory size includes N/2 memory elements, the feedback connection is negative and a factor of ?½ is provided at the output of the memory loop. Such a repetitive controller may be used for instance in the disturbance compensation module of a drive servo system in a recording and reproducing apparatus including a head for recording data on a recording medium.

Abstract: This apparatus relates to a data carrier which rotates about an axis and on which a track is provided for containing said data, said track spiraling around a center, which apparatus comprises an angle measurer for many purposes. For obtaining this angular position information, for example an eccentricity measurer is used. The eccentricity is defined by the non-coincidence of the center and the axis. Application: The invention is well suited to small-size optical discs, CD systems, DVD systems, and Blu-Ray systems.