US 4,796,247 AGranted

Compact disc (CD) player and method of compensating for tracking jumps

AssigneeBlaupunkt-Werke GmbH

InventorUlrich Vogelsang

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Abstract

To provide for continuity of audio output from a compact disc (CD) player, installed in an environment subject to shock or vibration, for example in a motor vehicle, the CD player includes an extra write-read memory (31), placed in the signal processing path of a signal scanned by an optical scanning system to a digital/analog converter in advance of an audio output system (AR), a repositioning system (36) to reposition the optical scanning optical system on a track which may have been lost due to a jolt or vibration, and a synchronizing system to synchronize writing in the write-read memory after repositioning of the optical scanning system at the end of previously written data in said write-read memory immediately in advance of tracking loss. Tracking loss can be sensed by determining loss of information data, or sensing of a scanning beam from the optical scanning system impinging on the mirror surface of the CD, with the number of tracks being jumped being determined by comparing timing data included in the CD scanned data with previously recorded data to thereby determine the length of track, and hence the number of track spirals which were skipped or jumped. Preferably, scanning and writing after detection of a tracking jump and repositioning is accelerated to rapidly refill the write-read memory, for example by increasing an operating clock rate while maintaining constant the read-out rate from the write-read memory (31).

Claims22

Dependent claims

Compact disc player, particularly for placement in unstable locations, especially in a motor vehicle, and for reproduction of data stored on a compact disc (CD) (10) located on the player, in which the data are stored on the CD along spiral tracks,

said player having a disc drive motor (11) for rotating the disc;
an optical scanning system (13) mechanically relatively at least radially movable with respect to the disc and producing scanning output signals;
signal processing means (17, 18, 25) coupled to receive the scanning output signals, said signal processing means storing groups of scanning outpt signals in data blocks and processing said blocks of signals and providing digital audio output signals;
means (26, LPF, L, R) for receiving said digital output signals and converting said digital output signals into analog audio output signals;
a tracking detector (20) for detecting tracking of the optical scanning system (13) on the tracks of the disc (10);
a tracking servo system (14, 15, 21) coupled to the tracking detector for maintaining the scanning optical system (13) on said tracks,
and comprising, in accordance with the invention,
a write-read memory (31) included in the signal processing means in the path of the signal from said
system to form the digital audio output signal, said write-read memory providing intermediate storage of the data blocks, and being arranged for continuous read-out of the data in the blocks and application thereof to said means for converting the digital output signals to analog output signals;
a repositioning system (36) coupled to the optical scanning system (13) for resetting the optical scanning system after a tracking jump;
and synchronizing means (37) coupled to the write-read memory (31) for synchronizing the initiation of writing into the write-read memory after repositioning of the optical scanning system (13) with the end of writing or recording in said memory of a data block in advance of a track jump.

8 more elements

Method of repositioning an optical scanning system (13) of a compact disc player, upon subjecting the disc player to shock, vibration or the like, particularly for a compact disc player placed in an unstable position, such as in a motor vehicle, said compact disc player storing data on a compact disc (10) located thereon, in which the data are stored on the compact disc (CD) along spiral tracks,

said player having a disc drive motor (11) for rotating the disc;
an optical scanning system (13) mechanically relatively at least radially movable with respect to the disc and producing scanning output signals;
signal processing means (17, 18, 25) coupled to receive the scanning output signals, said signal processing means storing groups of scanning output signals in data blocks and processing said blocks of signals and providing digital audio output signals;
means (26, LPF, L, R) for receiving said digital output signals and converting said digital output signals into analog audio output signals;
a tracking detector (20) for detecting tracking of the optical scanning system (13) on the tracks of the disc (10);
a tracking servo system (14, 15, 21) coupled to the tracking detector for maintaining the scanning optical system (13) on said tracks,
and comprising, in accordance with the invention, the steps of
buffer-storing the digital data blocks in a write-read memory (31);
continuously reading-out said stored data at a predetermined read-out rate (f.sub.const) for deriving therefrom the analog audio output signals;
repositioning the optical scanning means after detecting a tracking jump;
and synchronizing the initiation of further writing in the buffer write-read memory after repositioning of the optical scanning means with termination of data recorded in the write-read memory prior to detection of a track jump.

8 more elements

Dependencies are inferred from the claim text.

Facts

Application: 07/054,688Filed 27 May 1987
Priority: DE 36192587 Jun 1986
Granted: 3 Jan 1989
Term ends: Not estimatedThe source records don’t support an estimate.

Classification12 codes

G11B 7/0946
With provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record…
G11B 7/005
Recording, reproducing or erasing methods; Read, write or erase circuits therefor: reproducing
G11B 19/04
Control of operating function, e.g. switching from recording to reproducing: arrangements for preventing, inhibiting, or warning against double…
G11B 20/10527
Digital recording or reproducing: audio or video recording; Data buffering arrangements