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US 4,055,377 AGranted
Magnetically orientable retroreflectorization particles
AssigneeMinnesota Mining and Manufacturing Company
InventorsRandall L. Erickson, Terry R. Bailey
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AssigneeMinnesota Mining and Manufacturing Company
InventorsRandall L. Erickson, Terry R. Bailey
Estimating the term…
Novel magnetically orientable retroreflectorization particles permit application of highly oriented retroreflective coatings. The retroreflectorization particles individually comprise at least one transparent microsphere, specular reflective means in optical connection with a first portion of said microsphere so as to provide retroreflection of light incident on the opposed portion of the microsphere, and a magnetic layer underlying said specular reflective means and having a magnetic axis parallel to the optical axis on which said first and opposed portions of the microsphere are aligned. When the particles are applied to a substrate in the presence of a magnetic field having flux lines of appropriate polarity perpendicular to the substrate, the particles tend to become aligned in a common direction that retroreflects light incident on the coating.
A mass of discrete retroreflectorization particles useful for forming a retroreflective coating on a substrate, the individual particles each comprising at least one transparent microsphere, specular reflective means in optical connection with a first portion of the microsphere so as to provide retroreflection of light incident on the opposed portion of the microsphere, and a magnetic layer underlying the specular reflective means and having a magnetic axis parallel to the optical axis on which said first and opposed portions of the microsphere are aligned, whereby when the particles are coated onto a substrate in the presence of a magnetic field having flux lines of appropriate polarity perpendicular to the substrate, the particles tend to become aligned in a common direction that retroreflects light incident on the coating.
A mass of discrete retroreflectorization particles useful for forming a retroreflective coating on a substrate, the individual particles each comprising one or more transparent microspheres arranged as a closely packed monolayer, a segment of binder material in which said microspheres are partially embedded, specular reflective means in optical connection with the embedded portion of the microspheres so as to provide retroreflection of light incident on the portion of the microspheres opposite from the embedded portion, and magnetic particles dispersed in said binder material and aligned so as to provide the retroreflectorization particles with a magnetic axis parallel to the optical axis on which said opposite and embedded portions of the microspheres are aligned, whereby when the particles are applied to a substrate in the presence of a magnetic field having flux lines of appropriate polarity perpendicular to the substrate, the particles tend to become aligned in a common direction that retroreflects light incident on the coating.
Dependencies are inferred from the claim text.