Deutsche Thomson-brandt Gmbh

Thomson Licensing S.a.

Lieu Kim Dang

Heinz-J&ouml;rg Schroeder

Hartmut Richter

Christoph Dietrich

Friedhelm Zucker

Fang Lei

Christian Buchler

Christian Buechler

Heinz-J&ouml;rg Schr&ouml;der

An apparatus for reading from and/or writing to optical recording media on which data markings are arranged along tracks arranged next to one another. The apparatus according to the present invention comprises a light source, a focusing means and an intensity distribution converter. In the present invention, both the extent of the focus spot of the primary beam is reduced and the disadvantages occurring due to the secondary beams are reduced. In an exemplary embodiment, the intensity distribution converter comprises a filtering strip arranged in the region of the focusing means.

Apparatus for reading from and/or writing to optical recording media

The present invention relates to an apparatus for reading from and/or writing to optical recording media with optical scanner, light source, focusing means, tilting-detection device and tilting-compensation device. The object of the invention is to propose an apparatus and a method, which enables optimum compensation of tilting using as few apparatus functions as possible. This is achieved according to the invention by using a tilting-detection device comprising an optical grating, a detector element, a control device for controlling light source and the focusing means and a control device controlling for the tilting-compensation device.

Apparatus for reading from or writing to optical recording media having a tilting-compensation device

The present invention relates to a device for reading from or writing to optical recording media, which device has a scanning beam generation means, a focusing means and a photodetector comprising at least two detector zones and serving to receive zeroth- and first-order diffraction beams from the recording medium. The object of the invention is to obtain a reduction in interfering influences in a signal derived from signals of the photodetector, a signal such as, for example, a focus error signal or a track error signal. This object is achieved by virtue of the fact that a beam splitting means is provided, which splits a light spot falling onto the photodetector into two separate partial spots. The device is, for example, a CD or DVD player, but in particular a recording and reproduction device for so-called DVD-RAMs or similar optical recording media.

Device for reading from or writing to optical recording media

A device for reading from or writing to optical recording media comprising a scanning beam generation means, a focusing means and a photodetector comprising at least two detector zones and serving to receive zeroth- and first-order diffraction beams from the recording medium. The object of the invention is to obtain a reduction in interfering influences in a signal derived from signals of the photodetector, a signal such as, for example, a focus error signal or a track error signal. This object is achieved by virtue of the fact that a beam splitting means is provided, which splits a light spot falling onto the photodetector into two separate partial spots. The device is, for example, a CD or DVD player, but in particular a recording and reproduction device for so-called DVD-RAMs or similar optical recording media.

A device for writing to and/or reading from optical recording media having different structures is described, for example, a device which is suitable both for writing to/reading from digital videodisks (DVD) and conventional CD's. Provision is made for measuring the intensity of each peak in the mirror signal while the objective lens is moving to the recording medium. The intensity e.g. at the instant of the positive-negative crossing of the focus error signal is taken in this case. The type of optical recording medium is determined from the time characteristic and/or the height distribution of the peaks. In order to identify the type of optical recording medium, different properties of the optical recording medium are taken into account, such as reflectivity of the corresponding reflective surface, reduced intensity modulation due to spherical aberration, time characteristic and the like.

Device for writing and/or reading optical recording medium of various designs

The present invention relates to a recording or replay device, and to a method for recognizing a focussing status. The object of the invention is to provide a method of this type and a recording or replay device, with the facility of producing significant astigmatism in the reflected light beam (,) simply and cost-efficiently without elaborate alignment. This object is achieved by the use of a birefringent element (,). The invention is, in particular, suitable for use in a recording or replay device for writing to or playing back optical recording media (,) such as CDs, video discs, DVDs and the like.

Recording or replay device and method for recognition of a focussing status

Tracking error signal in an optical read/write device, such as a CD ROM, are fine tuned for deviations in the positions of the lens structure normal to the recorded medium to provide more precise tracking control. Track error signal is developed by means of DPD-TE circuitry, using for example, signals from a four quadrant photodetector. Selected pairs of the signals from the photodetector are summed and the sums are differenced to develop an intermediate signal. The intermediate signal is amplified with a gain proportional the reciprocal of the intensity of light received by the photodetector, and thereafter combined with the track error signal to provide a corrected track error signal.

Device for scanning optical discs using phase detection in a system with

A device for corrected-focus scanning of information while recording on and/or replaying information from a recording medium is based on a radiation source which provides a scanning beam, a focusing objective lens and a radiation-sensitive detector system. A diffraction element for deriving a focus error signal is arranged in the space between the focusing objective lens and the detector system, at a predetermined, fixed distance, the diffraction element being designed such that two focus planes result which are physically separated from one another. The detector system is located between the separate focus planes such that the size ratios, which change in the event of defocusing, of the symmetrically imaged focus spot can be used to derive the focus error signal.

Optical disc recording or playback device with corrected focus optical

An optical scanning device having a holographic optical element for receiving a scanning beam which has been influenced by a recording medium. One aspect of the invention is to use an optical spatial filter to obtain the information signals. A further aspect is to image the entire area of the scanning spot on only one detector and to use the complete light component, as a result of which the power component is increased and the requirements for adjustment of a plurality of elements with respect to one another are reduced.

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Villingen-Schwenningen, Germany

Lieu Kim Dang