Four read and write heads on a drum arranged to prevent overlapping of tracing periods

Claim 1

A magnetic storage apparatus for avoiding overlapping of tracing periods of first and second write only magnetic heads and first and second read only magnetic heads of the storage apparatus during operation comprising: a rotating drum which has a central axis and which has a periphery, contacted by a magnetic tape at a predetermined contact angle α of a value greater than 90°; said periphery of said rotating drum having located thereon said first and second write only magnetic heads and said first and second read only magnetic heads, the first and second write only magnetic heads and the first and second read only magnetic heads contacting the tape during operation of the apparatus, wherein a relation between locations of the first and second write only magnetic heads and the first and second read only magnetic heads, is defined with the angle α as: θ1≧α θ2≧α θ3≧α θ1+θ2+θ3≦360° ×n-α where n: represents a positive integer representing how many rotating of the drum are required of processing one frame, θ1: a horizontal angle spanned between the first write only magnetic head and the first read only magnetic head with respect to the central axis of the rotating drum, θ2: a horizontal angle spanned between the first read only magnetic head and the second write only magnetic head with respect to the central axis of the rotating drum and θ3: a horizontal angle spanned between the second write only magnetic head and the second read only magnetic head with respect to the central axis of the rotating drum are given; wherein the values of θ1, θ2, θ3 and n are calculated based of a value of contact angle α greater than 90°.