Deutsche Thomson-brandt Gmbh

Thomson Licensing

Thomson Licensing S.a.

Peter Mahr

Gerhard Reiner

Klaus Oldermann

Michael Huonker

Juergen Kaaden

Jurgen Kaaden

J&uuml;rgen Kaaden

Hartmut Peters

Werner Scholz

Erich Geiger

Friedrich Timmermann

Martin Kuner

Jürgen Kaaden

Christian Vollmer

Bernd Wessolly

Andreas Kluger

Bruno Weihs

Wiebke Schone

The present invention relates to a method for analyzing abnormal regions on an optical recording medium. The method includes the steps of:

Method for analyzing an abnormal region on an optical recording medium

The invention proposes an appliance for recording or playing back information having means for detecting or moving the position of a scanning device over a disc with a wobble track, said appliance being able to be used both in recorded and in unrecorded areas of the disc and hence being able to be used both for write-once and for rewriteable recording media with a wobble track, and said appliance additionally permitting fast determination of the scanning location without decoding of scanned-location information which is contained in the wobble track. According to the invention, a wobble signal is scanned from the wobble track on the disc using a scanning device, and a wobble frequency contained in the wobble signal detected from the disc is used for detecting or moving the position of the scanning device. In this regard, the wobble frequency is related to the number of revolutions or the rotation speed of the disc or to a wobble frequency known for a reference location on the disc, which allows the position of the scanning device to be detected or moved without decoding of scanning-location information which is contained in the wobble signal. To generate the wobble frequency contained in the wobble signal, a circuit block is provided which contains a phase comparator, a bandpass filter, a voltage-controlled multivibrator and a digital phase shifter and is used to generate a wobble-frequency signal.

Appliance for recording or playing back information having means for detecting or moving the scanning location on a disc with a wobble track

A method for tracking control of a head unit with respect to data tracks on a magnetic tape determines a first tracking signal and a second tracking signal from control tracks recorded on the tape. The data tracks are divided into successive data sections, each of which is subdivided into an initial region and a useful region. A first control track extends over the entire length of the data section. In addition to this, a second control track is provided in the initial region of each data section. A first tracking signal is generated from the first control track and a second tracking signal is generated from the first and second control track. A difference signal is generated and stored, which is based on a comparison of the first and second tracking signal. A tracking control signal applied to an actuator adjusting the head unit is generated from the second tracking signal when the second tracking signal is available. The tracking control signal is generated from the first tracking signal and the difference signal when the second tracking signal is not available.

Method for tracking control

The invention proposes an appliance for recording or playing back information having means for signal generation from a wobble signal which is scanned from the undulating track on a recording medium, such as a DVD+RW. According to the invention, a signal scanned from the undulating recording track on the recording medium is supplied to a circuit arrangement for generating a clock signal which is both a square-wave voltage whose phase is synchronous with that of the signal and a signal with an even-numbered multiple of the frequency of the wobble signal contained in the signal. In this regard, the invention provides a phase locked loop which is synchronized with the signal and contains a frequency divider for actuating a digital phase shifter and for providing a clock signal which is a phase-synchronous square-wave voltage having the frequency of the wobble signal. The phase comparator provided is a multiplier which is formed using a changeover switch to which the signal and the inverted signal are applied. For decoding information contained in the waveform of the recording track on the recording medium, a circuit arrangement similar to the aforementioned multiplier is used whose changeover switch is actuated with the clock signal and to which a low-pass filter is connected. The signals generated using the means for signal generation are then made available to further functional units in the appliance for recording or playing back information for recording media with a wobble track.

Appliance for recording or playing back information having means for signal generation from a wobble signal

A data player or a method in which a reading and/or writing head is positioned according to anyone of 3 methods or combinations thereof: Calculating a desirable speed curve to position the head from a first to a second position and adjust the speed of the head's movement to the desirable speed, calculating and outputting an amount of energy to a driving mechanism to move the head a determined number of steps, increasing the power applied to a driving mechanism until the head is moved for one step. The positioning may additionally be used to perform coarse positioning while the head is positioned on a track of a data medium using a fine positioning mechanism.

Position control of opticial head in a recording device

A disc speed control device for use in a disc player and/or recorder having a pick-up for reading/recording data. The device comprises an inner loop which regulates a determined disc rotation speed value received at its input and an outer loop which delivers this speed value depending on a frequency at which data is read by the pick-up. The present invention is particularly useful in multistandard disc drives which need to adjust to different disc speed modes, for example, constant angular velocity, or constant linear velocity.

Disc speed control device

a data player or a method in which a reading and/or writing head is positioned according to anyone of 3 methods or combinations thereof: Calculating a desirable speed curve to position the head from a first to a second position and adjust the speed of the head's movement to the desirable speed, calculating and outputting an amount of energy to a driving mechanism to move the head a determined number of steps, increasing the power applied to a driving mechanism until the head is moved for one step. The positioning may additionally be used to perform coarse positioning while the head is positioned on a track of a data medium using a fine positioning mechanism.

Optical head position control for optical recording device

A device and a method are disclosed for obtaining a corrected servo control signal in a servo control loop take in account a dynamic behavior of the servo control signal to calculate a new threshold for this signal. If the servo control signal for any reason goes beyond the extremum then it is corrected by replacing it with the value of the threshold. Depending on the difference between the servo control signal and the threshold the new threshold may be greater or smaller than the previous threshold value. The threshold may be a maximum or a minimum thus limiting the servo control in its maximum or in its minimum value.

Corrected servo control signal in a servo control loop

The present invention relates to a device for reading from or writing to recording media in disc form which has an unbalance compensation means. The object of the invention is to propose a device of this type which has the smallest possible unbalance even when exchangeable recording media are used. This object is achieved according to the invention by virtue of the fact that the unbalance compensation means is a centrifugal force generation means which generates a centrifugal force which is variable during operation. According to another aspect of the present invention, provision is made for the unbalance compensation means to be a positioning means for positioning the recording medium. The field of application of the invention includes, inter alia, devices for reading from and/or writing to optical recording media such as CD, CD-ROM, DVD, DVD-ROM, DVD-RAM and the like.

Device for reading from or writing to recording media in disc form exhibiting unbalance

A method for controlling a phase relation between a head drum and a tape feed system, of a type wherein digital picture data is subdivided into blocks having an assigned pointer value each and wherein the pointer values define which part of the picture the block of picture data represents includes the steps of: incrementing or decrementing a location in a measured value with a corresponding pointer value with corresponding data block in a reproduced data stream, monitoring the content of the locations in the measured value store after a certain amount of reproducing time by means of determining the distance between pointer value regions which have been reproduced more often than the regions in-between, thereby taking into account the difference in reproducing frequency between the more often reproduced regions and the more seldom reproduced regions according to the measured value store entries, and determining a phase correction value for the control of the phase relation between the head drum and the tape feed systems based on the distance between pointer value regions.

Method and device for controlling the phase relation between a head drum and tape feed system of a magnetic tape recording device

In a tape transport for recording and/or reproducing signals by means of a recording medium using separate winding motors for driving the winding plates, the drive of the winding motors servo units is constructed as open-loop control devices and/or closed-loop control devices. Such servo units can advantageously be used for open-loop control and/or closed-loop control of the drive of the winding motor even during a braking operation.

Optimized winding drive

The invention relates to a tracking device in which a position of a coil driven actuator is determined using a sensor coil. A reference signal 12 having a determined voltage and frequency is fed to a driven coil. A position of the coil driven actuator is proportional to a distance between the driving coil and the sensor coil. The sensor coil produces an alternating voltage induced by an alternating magnetic field emitted by the driving coil. The alternating voltage is used to determine the position of the actuator.

Tracking device with a coil driven actuator and a sensor coil to

An information storage medium has at least a longitudinal bundle comprising three servo tracks (3, 4, 5). The bundle is arranged in consecutive tracking units (T(N)) of a determined longitudinal length. Surfaces of said servo tracks present either a first or a second characteristic (6, 7) and vary in size and distribution inside the tracking units. The bundles may contain longitudinally stored identification information. Methods for obtaining tracking signals indicating a transversal offset between a reading head and the bundle and for retrieving identification information are disclosed. Also methods for obtaining tracking units in which transversal tracking code is combined with distinct information are described.

Combined longitudinal and transversal tracking

The invention relates to a device for positioning a first element relatively to a second element. The device according to the invention uses lifting means comprising a cam element and actuator means to actuate the cam element. The cam element has a plurality of contiguously arranged sectors with machined edges belonging to first and second interleaved groups. The machined edges are shaped such that a response of the lifting means to the actuator means has different values for sectors of said first and second group thereby providing alternately a coarse positioning and a fine positioning. The device may for example be used to position a multitrack magnetic tape and a magnetic writing/reading head relatively to each other.

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Weiler, Germany

Peter Mahr