Graham Magnetics Incorporated

Carlisle Corporation

William A Manly

Robert J Deffeyes

To indicate the origin of manufacture of the components of a roofing system, magnetically permeable particles are incorporated into the components. The particles are preferably loaded into the lap sealant and adhesive used to form field splices. Thus loaded, the lap sealant and/or adhesive has magnetically permeable properties or characteristics which are electromagnetically detectable through and beyond one layer of rubber sheeting. Detection of these particles provides an indication of origin of the material.

Noninvasively identifiable membrane roof system

Absorptive shields for transmission lines, especially those tending to radiate electromagnetic wave lengths within a frequency range of from about 10.sup.6 to about 10.sup.10 hertz, especially 10.sup.7 to 10.sup.10 hertz. The shields are flexible materials filled with ferromagnetic, or ferrimagnetic, powders of selected particle size and distribution.

EMI-Suppression from transmission lines

An improved magnetic recording member of the disc type, the article of the invention is polymodal wherein one mode is formed of a first population of magnetic particles which have a coercivity differing by at least 200 oersteds from the coercivity of particles in another mode. These latter particles are, preferably, metallic magnetic particles oriented in a vertical direction and are in a thin layer over said first population of magnetic particles. This combination overcomes existing limitations on (a) disc products, and (b) the preferred metallic particles heretofore known.

Polymodal magnetic recording member

Playback method and apparatus compensate exactly for both tracking and speed errors due to any eccentricity in the information track on a rotating recording member during playback by moving the read head in a circular path having the same radius, angular velocity and phase as the circle of eccentricity of the track.

Recording track eccentricity compensation method and means

An improved magnetic recording member of the disc type. The article of the invention is formed, preferably, of metallic magnetic particles oriented in a vertical direction. This combination overcomes existing limitations on (a) disc products, and (2) the preferred metallic particles heretofore known.

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Arlington, TX, United States of America

William A Manly