Flashing retroreflecting device
AssigneeMinnesota Mining and Manufacturing Company
InventorsBryan L. Klaenhammer, William H. Long
Life of this patent
Estimating the term…
Abstract
A reflecting device providing a flashing reflection of light incident on the device toward an intended observer includes a converging Fresnel lens for receiving light directed onto the device and for focusing the light within the focal plane of the lens, through which plane a reflector is periodically moved to intermittently reflect the light. In one embodiment, the reflector is positioned to retroreflect the light back through the lens toward an observer positioned adjacent the source of light. In another embodiment, the reflector is positioned to reflect light transmitted through a first Fresnel lens toward another Fresnel lens so as to be visible by an observer of the other lens.
Claims13
In a signalling device comprising a housing;
- a lens positioned in an opening in said housing for receiving light, a reflector within said housing substantially at the focal plane of said light receiving lens, which reflector receives and reflects light from said light receiving lens along an optical path toward said lens, and reflectance control means for varying said optical path, the improvement wherein said lens comprises at least one converging Fresnel lens and said reflectance control means includes means periodically interposed into said optical path to thereby vary said path, said reflectance control means comprising a support means for supporting said reflector and drive means for oscillating said support to cause said reflector to periodically move to thereby vary said optical path, whereby light incident on said device such as that provided by vehicle headlights is periodically variably reflected, thus accentuating the detection of the reflected light, affording a flashing signal light to an observer of said device.
In a signalling device comprising a housing;
- a lens positioned in an opening in said housing for receiving light, a reflector within said housing substantially at the focal plane of said light receiving lens, which reflector receives and reflects light from said light receiving lens along an optical path toward said lens, and reflectance control means for varying said optical path, the improvement wherein said lens comprises at least one converging Fresnel lens and said reflectance control means includes means periodically interposed into said optical path to thereby vary said path, whereby light incident on said device such as that provided by vehicle headlights is periodically variably reflected, thus accentuating the detection of the reflected light, affording a flashing signal light to an observer of said device, wherein said reflectance control means comprises a support means for rigidly positioning said reflector within said housing and drive means coupled to a light shutter for periodically interrupting light incident on said reflector.
In a signalling device comprising a housing;
- a lens positioned in an opening in said housing for receiving light, a reflector within said housing substantially at the focal plane of said light receiving lens, which reflector receives and reflects light from said light receiving lens along an optical path toward said lens, and reflectance control means for varying said optical path, the improvement wherein said lens comprises at least one converging Fresnel lens and said reflectance control means includes means periodically interposed into said optical path to thereby vary said path, whereby light incident on said device such as that provided by vehicle headlights is periodically variably reflected, thus accentuating the detection of the reflected light, affording a flashing signal light to an observer of said device, further comprising a second Fresnel lens positioned in another opening in said housing at an angle with respect to said light receiving lens, said reflector is mounted to reflect light passing through said light receiving lens along an optical path through said second lens to alert an observer viewing said second Fresnel lens to the presence of said light.
Dependencies are inferred from the claim text.