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EP0170518A2
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EP
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Directionally imaged retroreflective sheeting
Assignee: 3M Co
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Filing: 1985-07-30
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Granted: —
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Expires: 2005-07-30
Abstract
Abstract Retroreflective sheeting comprising a monolayer of transparent glass microspheres partially embedded in a binder layer, a specularly reflective layer covering the back surfaces of the microspheres, and laser-formed wings viewable only within a limited conical field of view, the images being provided by tiny ellipsoidal cavities in the microspheres, each opening through a back surface of the microsphere.
Inventors
- 👤 Bruce D. C/O Minnesota Mining And Orensteen
- 👤 Thomas I. C/O Minnesota Mining And Bradshaw
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 15:12
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/12; G02B5/126; G02B5/128; G06; G06K; G06K19/00; G06K19/06; G06K19/06009; G06K19/06046; G06K19/08; G06K19/10; G06K19/14
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
78 words
Retroreflective sheeting comprising a monolayer of transparent microspheres partially embedded in a binder layer and a specularly reflective layer covering the back surfaces of the microspheres, which sheeting contains at least one image viewable from the front of the sheeting only across a conical field of view, characterized in that said image is provided by tiny cavities, each opening through a back surface of a microsphere, and substantially every opening is smaller than the depth of the cavity.
Claim 2
Dependent Claim
78 words
Retroreflective sheeting comprising a monolayer of transparent microspheres partially embedded in a binder layer and a specularly reflective layer covering the back surfaces of the microspheres, which sheeting contains at least one image viewable from the front of the sheeting only across a conical field of view, characterized in that said image is provided by tiny cavities, each opening through a back surface of a microsphere, and substantially every opening is smaller than the depth of the cavity.
Claim 3
Dependent Claim
42 words
Retroreflective sheeting as defined in claim 1 wherein the wall of each cavity is substantially an ellipsoid, the major axis of which extends orthogonally to the surface of the microsphere, and each opening is smaller than the minor axis of the ellipsoid.
Claim 4
Dependent Claim
20 words
Retroreflective sheeting as defined in claim 1 or 2 wherein said binder layer is rendered opaque by a light-colored pigment.
Claim 5
Dependent Claim
14 words
Retroreflective sheeting as defined in claim 3 wherein the pigment is Ti0 2 .
Claim 6
Dependent Claim
46 words
Retroreflective sheeting as defined in claim 1 to which is sealed a transparent protective film in a grid pattern of narrow sealed areas and relatively broad unsealed areas, and within the unsealed areas the front surfaces of the microspheres are optically exposed to an air interface.
Claim 7
Dependent Claim
15 words
Retroreflective sheeting as defined in claim 5 wherein the protective film contains a transparent dye.
Claim 8
Dependent Claim
12 words
Retroreflective sheeting as defined in claim 1 wherein the microspheres are glass.
Claim 9
Dependent Claim
90 words
Method of directionally imaging retroreflective sheeting containing a monolayer of transparent glass microspheres selected to focus a beam of visible light substantially at a reflective layer which covers the back surfaces of the microspheres, the front surfaces of which are open, said method comprising directing an infrared laser beam at a specific angle toward the front of the sheeting to form tiny cavities, each opening through the back surface of a microsphere along the axis of the laser beam, substantially every opening being smaller than the depth of the cavity.
Claim 10
Dependent Claim
90 words
Method of directionally imaging retroreflective sheeting containing a monolayer of transparent glass microspheres selected to focus a beam of visible light substantially at a reflective layer which covers the back surfaces of the microspheres, the front surfaces of which are open, said method comprising directing an infrared laser beam at a specific angle toward the front of the sheeting to form tiny cavities, each opening through the back surface of a microsphere along the axis of the laser beam, substantially every opening being smaller than the depth of the cavity.
Claim 11
Dependent Claim
17 words
Method as defined in claim 8 wherein the wavelength of the laser beam is approximately one micrometer.
Claim 12
Dependent Claim
45 words
Method as defined in claim 8 wherein a transparent protective film is sealed to the retroreflective sheeting in a grid pattern of narrow sealed areas and relatively broad unsealed areas within which the front surfaces of the microspheres are optically exposed to an air interface.
References Cited (Backward Citations)
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