Deutsche Thomson-brandt Gmbh

Hirohito Takagi

Richard Rutschmann

Engelbert Laufer

Dietmar Peter

Friedrich Fueldner

Volker Politz

Olivier Lannuzel

Heinrich Schemmann

Juergen Baeumle

A control unit is used to set a first reading speed and a second reading speed of the information stored on the information medium as a function of a predetermined occupancy of the buffer below its storage capacity, for the purpose of reducing the number of returns. The drive motor which produces the reading speed is connected via a switch to the driver which drives it and, during the reduction of the reading speed to a predetermined value or until the occupancy of the buffer falls below a predetermined occupancy, the power supply to the drive motor which produces the reading speed, is reduced by means of a switch for the purpose of reducing the power consumption. Subcode information is preferably used to synchronize the data in the buffer after an interruption, and the buffer is preferably arranged between a first assembly for the pulse shaping of the signal read from the information medium and a second assembly for error correction.

Vibration-resistant playback device

The present invention relates to a device for writing to or reading from optical recording media which have data tracks for recording or reading out information. It has a scanning means for scanning the data tracks, a detection means which emits a signal which is modulated in accordance with the information stored on the optical recording medium and a track detector, which generates a mirror signal by means of a reference value transmitter, which mirror signal indicates whether the scanning means is scanning a data track or the region between two tracks. The device is capable of forming a reliable mirror signal without a high outlay. For this purpose, the reference value transmitter is designed as an adaptive reference value transmitter to which the mirror signal is fed as input variable.

Device for writing to or reading from optical recording media

Recording or playback devices for optical recording carriers have a servo control circuit which controls the tracking and the focus of an optical scanning unit 1 with reference to an error signal. According to the invention, the error signal is non-linearly amplified upstream of the servo controller, in order to process strong external mechanical effects, normally referred to as shocks, in such a way that the tracking and the focus are retained or adjusted. If there is a defect, such as a scratch on the disc etc., a defect detector and a linear amplifier connected in parallel with the non-linear amplifier are additionally used, the linearly amplified or non-linearly amplified error signal being fed to the servo controller as a function of the output signal of the defect detector. The sign of the error signal, which includes direction information, is retained in the case of the non-linearly amplified error signal.

Recording or playback device for optical information carriers having a

A method and an arrangement for a vibration-resistant playback device, in which uninterrupted and undisturbed reproduction of information is assured despite vibrations, by use of a 'shock-proof memory' by arrangement of a buffer between an EFM demodulator, and a de-interleaving and error correction unit, which provides the digital audio information. The buffer can be made of an ARAM (audio RAM), which is less expensive than a DRAM. The ARAM can be partially defective, and its use is made possible by the arrangement before the error correction unit. Subcode information is preferably used to synchronize the data in the buffer following an interruption.

A method is specified for processing the output signals A to F of an optoelectronic scanner (3) in a replay or recording appliance for replaying from or recording onto an optical recording medium having the following method steps: as well as an appliance with a corresponding input circuit of a digital servo controller: first of all, the output signals A to F are supplied directly to an A/D converter (2) without the interposition of a low-pass filter, and are digitized with n-times oversampling. The digitized output signals are then supplied to a k-th order comb filter (4) by means of which undersampling of the signals to the normal sampling frequency (44.1 kHz) is carried out. After this, the undersampled output signals A' to F' of the comb filter (4) are supplied to a trimming and correction circuit (6) in which trimming and correction, of OFFSET and BALANCE are respectively carried out. Finally, the trimmed/corrected output signals A' to F' are supplied to the trimming and correction circuit of a digital servo circuit (1), by means of which a focusing error signal (FE) and a track deviation error signal (TE) are produced.

Method for processing the output signals of an optoelectronic scanner in

A control unit sets a first reading speed and a second reading speed of the information stored on the information medium as a function of a predetermined occupancy of the buffer below its storage capacity. The drive motor, which produces the reading speed, is connected via a switch to the driver which drives it and, during a reduction of the reading speed to a predetermined value or until the occupancy of the buffer falls below a predetermined occupancy, the power supply to the drive motor which produces the reading speed, is reduced by means of the switch for the purpose of reducing the power consumption.

Vibration-resistant playback device having reduced power consumption

A reproducing and/or recording device for reproducing, or for recording on, an optical recording medium, having a tracking sychronization circuit (1), which has a variable center frequency generator (12, 13). The tracking synchronization circuit (1) can be operated with different center frequencies depending on application, and this has the advantage that identically designed tracking synchronization circuits (1) can be used for different purposes. It is advantageous that adaptive adjustment of a center frequency once prescribed is additionally possible during operation, thus increasing the capture range of the tracking synchronization circuit.

Reproducing or recording device for reproducing, or recording on, an

A control unit, stores addresses of a write pointer of a buffer in the case of the last valid subcode information and starts with a synchronization byte following an interruption. The synchronization byte is provided for the synchronization of the data stream in the buffer, an item of address information which identifies the interruption location in the data stream, the starting point of the synchronization being formed by a valid subcode, the address information being used as a reference both for the location of the interruption on the information medium and for the last valid data in the buffer and the writing in the buffer. This is done so that uninterrupted reproduction of information is provided despite vibrations in the playback device.

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Chiba, Japan

Hirohito Takagi