Back to results
US 4,303,953 AGranted
Method of positioning reproducing elements and device for carrying out the method
AssigneeU.S. Philips Corporation
InventorHendrik J. Sanderson
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeU.S. Philips Corporation
InventorHendrik J. Sanderson
Estimating the term…
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.
A method of controlling the position of a pair of reproducing elements in an apparatus for reproducing signals recorded in a plurality of parallel tracks on a recording medium, said reproducing elements and said medium being arranged for movement relative to each other so that said elements consecutively read alternate tracks and the signals recorded in the tracks containing pilot signals such that the pilot signals from each pair of consecutively read tracks are spaced from each other by a predetermined, nominal time interval when the reproducing elements are spaced from each other by a predetermined, nominal distance in a direction transverse to the track direction, said method comprising the steps of:
In an apparatus for reproducing signals recorded in a plurality of parallel tracks on a recording medium, said apparatus including a pair of reproducing elements arranged for relative movement with respect to said medium so as to consecutively read alternate tracks on said medium, the improvement wherein the signals recorded in said tracks contain pilot signals such that the pilot signals from each pair of consecutively read tracks are separated by a predetermined, nominal time interval when the reproducing elements are spaced from each other by a predetermined, nominal distance in a direction transverse to the track direction, the improvement further comprising means for detecting the pilot signals read by said reproducing elements from said tracks, means for measuring the time interval between the pilot signals detected from each pair of consecutively read tracks, means for comparing said measured time interval with said nominal time interval, and means for generating a control signal indicative of the deviation of the distance between said reproducing elements in said transverse direction from said nominal distance when said measured time interval deviates from said nominal time interval by a predetermined amount.
In an apparatus for reproducing signals recorded in a plurality of parallel tracks on a recording medium, said apparatus including a pair of reproducing elements arranged for relative movement with respect to said medium so as to consecutively read alternate tracks on said medium, the improvement wherein the signals recorded in said tracks contain pilot signals such that the pilot signals from each pair of consecutively read tracks are separated by a predetermined, nominal time interval when the reproducing elements are spaced from each other by a predetermined, nominal distance in a direction transverse to the track direction, the improvement further comprising means for detecting the pilot signals read by said reproducing elements from said tracks, first means for generating a first series of pulses which are spaced from each other by time intervals equal to said nominal time interval, means for measuring the difference between the duration of a first time interval between one of said pulses of said first series and a first pilot signal detected from a first one of a pair of consecutively read tracks and the duration of a second time interval between the next succeeding pulse of said first series and a second pilot signal detected from the second of said pair of consecutively read tracks, and means for generating a control signal indicative of the deviation of the distance between said reproducing elements in said transverse directional from said nominal distance when said difference exceeds a predetermined value.
Dependencies are inferred from the claim text.