U.S. Philips Corporation

Hendrik J Sanderson

Hendrik J Bergmans

Jacob De Boer

Friedrich Sommer

A two-head recorder in which information is read from recording tracks which are substantially parallel to each other and which make an angle with the longitudinal axis of a tape-like recording medium. The recorder comprises two heads which are each mounted on a transducer for moving the head as a function of tracking signals for the two heads which appear alternately so that the two heads are alternately centered relative to the recording track. The tracking signals are also applied to a tape speed control circuit in order to control the speed of the tape-like recording medium depending upon the average value of the tracking signals.

Tape speed control device

Method and apparatus for positioning magnetic heads in a two-head helical scan video recorder, suitable control signals being generated for making the heads follow the tracks by means of piezoelectric transducers. The control signals applied to the two transducers are compared and when these control signals deviate from each other more than to a predetermined extent the one transducer receives the same control signal as the other transducer, so as to ensure that the two heads follow consecutive tracks.

Method of reading and/or writing information and apparatus for carrying

A method of recording information on a tape-like record carrier by means of a device provided with a rotary head disc on which a write head with controllable height is mounted for actively following the tracks. During recording tracking signals are written with the aid of a separate fixed head, which preferably also constitutes the erase head, and the write head follows the tracking signal recorded by the fixed head during the recording of information.

Method and apparatus for recording helical scan information and tracking

In video recorders where the video information is alternately recorded in oblique tracks by means of two heads, there are generally provided fine control mechanisms for centering the heads relative to the track to be followed. These mechanisms do not detect whether the two heads occupy a correct position relative to each other so that their position relative to each other may differ by an amount corresponding to one track or a group of tracks. The disclosed method of controlling the two heads so that they occupy a correct position relative to each other assumes the use of a recording medium with signals reproduced by the heads contain pilot signals such that in the case of a correct reading of two consecutive tracks, the detected pilot signals are spaced at a nominal time interval from each other, i.e. half the revolution period of the head disk. The time interval between the detection of two consecutively pilot signals is measured and if that time interval deviates from the nominal time interval by a predetermined amount, the position of the two heads relative to each other in a direction transverse to the recording tracks is corrected.

Method of positioning reproducing elements and device for carrying out

Method and device for controlling the position of a write or read head, which covers adjacent tracks on a record carrier, relative to at least one adjacent track, which tracks in addition to the information signals contain tracking signals, the tracking signal in n consecutive tracks having n different frequencies, where n.gtoreq.4, and the difference of the frequencies of the tracking signals of every two adjacent tracks with the frequency of the third signal, which frequency may differ from track to track, always yielding fourth signals with the same pair of lower frequencies, a control signal being derived from said fourth signals.

Method of controlling the position of a write or read head and a device

A method and apparatus for controlling the position of write-read heads with which information is recorded in a plurality of parallel tracks on a record carrier. In accordance with the invention a tracking signal is recorded in at least selected tracks during a first time interval. When the next track is written the supply of write signals to the write-read heads is interrupted for a second time interval, the first and second time intervals being selected in such a way that the track portions corresponding to said two time intervals adjoin each other. During the second time interval the cross-talk signal produced in the write-read head by the recorded tracking signal is measured and employed to produce a control signal for positioning the write-read heads.

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Eindhoven, Netherlands

Hendrik J Sanderson