Interlacing system for skip-filed magnetic recording and reproducing

Claim 1

A skip-field video recorder/reproducer comprising: means for recording composite video signals in oblique tracks on a moving magnetic tape, the signal in each track including a conventional video field, each field comprising video information arranged in a plurality of vertically displaced horizontal lines, a vertical sync signal and a horizontal sync signal, said means including a plurality of rotatable magnetic heads, said heads being angularly spaced and axially spaced so that certain of said heads are each normally aligned during playback with a field on an oblique track for tracing each entire field, and so that at least one of said heads is misaligned, said misaligned head tracing said track beginning at a point spaced one-half of a horizontal line from the beginning of said field; drive means for rotating said heads, said drive means comprising a servo system for controlling the speed of rotation of said heads, said servo system including first means when each of said heads is in a predetermined angular position for generating a first signal, second means when each of said heads is in a second predetermined angular position for generating a second signal, means for measuring the time period between the generation of each of said first signals and the generation of each of the succeeding of said second signals, means responsive to a deviation from a predetermined time period between the generation of each of said first signals and the generation of the succeeding of said second signals for generating successive velocity error signals, means responsive to said velocity error signals for controlling the speed of said drive means to reduce said error; switching means for successively operating said heads; means responsive to the generation of each of said first signals for actuating said switch means; and means during playback for substituting said first signals for said vertical sync signal.