Dynamic magnetic information storage or retrieval – Automatic control of a recorder mechanism – Controlling the record
Patent
1995-12-06
2000-10-03
Loomis, Paul
Dynamic magnetic information storage or retrieval
Automatic control of a recorder mechanism
Controlling the record
360 69, G11B 1548
Patent
active
061281522
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for regulating the speed of a tape for the recording and/or reproduction of items of information, such as a video tape for example, in an operational mode in which the tape is intended to come to a stop at predetermined positions.
BACKGROUND OF THE INVENTION
Known operational modes in which a tape for the recording and/or reproduction of items of information should come to a stop at predetermined positions are, for example, the so-called slow motion mode and the freeze frame mode of a video apparatus. Thereby, a video tape is scanned by a video head in such a way that individual items of picture and/or sound information recorded on this video tape are read out on each occasion for a defined time t. For this, the tape is wound so far that the items of information for a first picture come into the spatial region of the video head. After the time t, the tape is wound on in such a way that items of information for a next picture are located in the region of the video head. Later on, the reproduction of a further picture can occur, and so on.
Thereby, it is important that the tape be brought to a standstill as accurately as possible in such a way that the beginning of the current items of picture information always coincide exactly with the region of the video head. This means, in particular, that an exactly executed delaying or braking process has to be instituted at the end of each winding on sequence so that a precise stopping of the tape is ensured.
Known apparatus, such as video apparatus for example, institute a braking process after a defined winding on time, during which, braking means such as a motor, a mechanical brake or the like, are controlled by fixed, defined control signals. This means that tolerances, which are occasioned, for example, by manufacturing tolerances of the apparatus, by different video tapes, by temperature effects and the like, are not taken into account.
The object of the present invention is to further develop the course of a braking process of the said kind in such a way that a tape for the recording and/or reproduction of items of information is brought to a halt, as exactly as possible, at predetermined positions.
This object is achieved by a method in accordance with claim 1 and by an apparatus in accordance with the first apparatus claim.
SUMMARY OF THE INVENTION
Advantageous developments of the invention are specified in the appendant claims.
In accordance with the invention, a braking process which effects an exact stoppage of a tape for recording and/or reproduction, such as a video tape for example, is realised in that, at the beginning of the braking process, a target waveform is determined to which the actual values of the speed are controlled or regulated. These target values, or else, their time-related waveform, may be determined for example on the basis of the tape speed and/or position at the beginning of the braking process.
Further features, advantages and details of the invention are explained in the following embodiments with the help of the drawing. Therein
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a block circuit diagram of a preferred embodiment;
FIG. 2 provides a symbolic illustration of a video tape;
FIGS. 3, 4, 6 illustrate waveforms of the speed values of a video tape for the embodiment of FIG. 1;
FIGS. 5, 7 illustrate waveforms of the motor control voltages during a braking process.
DETAILED DESCRIPTION OF THE INVENTION
Before going into the detailed description of the embodiments, it is pointed out that the blocks individually illustrated in the Figures merely serve for a better understanding of the invention. Usually, individual ones or several of these blocks are combined into units. These may be realised in integrated or hybrid technology or as a programme controlled micro-processor or as part of a programme that is suitable for its programming.
The elements contained in the individual stages may also, however, be implemented separately.
FIG. 1 sho
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patent: 5287233 (1994-02-01), Lee et al.
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Deutsche Thomson-Brandt GmbH
Kolodka Joseph J.
Loomis Paul
Tripoli Joseph S.
Wein Frederick A.
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