Stock material or miscellaneous articles – Composite – Of inorganic material
Utility Patent
1994-03-15
2001-01-02
Robinson, Ellis (Department: 1772)
Stock material or miscellaneous articles
Composite
Of inorganic material
C359S527000, C359S530000, C359S536000, C359S537000, C428S691000, C428S917000
Utility Patent
active
06168876
ABSTRACT:
This invention relates to novel structures, useful, inter alia, as safety devices, which combine the desirable features of fluorescence, retroreflectivity and electroluminescence in a single structure. In a specific embodiment, the invention relates to highway safety and traffic control devices.
The use of fluorescent materials for improved daylight visibility and conspicuity is well known and is commonly practiced in such applications as hunter's vests, highway worker safety vests and plastic traffic control cones. Such materials use special dyes and pigments, which convert low wavelengths of light energy to higher wavelengths, thereby providing color emphasis, which offers good contrast with surroundings and, thus, higher visibility.
The use of retroreflective materials for improved nighttime visibility and conspicuity to improve safety conditions is also well known and is commonly practiced in applications such as highway signs and reflective strips attached to clothing and safety vests.
The use of fluorescent and retroreflective materials in combination for improved daytime and nighttime visibility also has been used commercially for many years. For example, the triangular slow moving vehicle emblem specified for use on vehicles traveling the highway at less than twenty-five miles per hour is composed of a center triangle made from fluorescent film and a border of retroreflective sheet. This design has been used for many years and is recognized internationally.
The U.S. Coast Guard places signs along the waterways consisting of various configurations of fluorescent film and retroreflective sheet in combination for both daytime and nighttime visibility.
The above illustrations represent the use of fluorescent and retroreflective materials in essentially the same plane, so that the fluorescent material and the retroreflective material are essentially side-by-side in the same device. This generally has been necessary, since, due to the construction of most retroreflective films, retroreflective film placed over a fluorescent film masks the corresponding fluorescent area, converting the fluorescent area to a retroreflective area. On the other hand, many fluorescent films and devices are opaque, precluding their use over retroreflective films.
Recently, transparent or translucent fluorescent films or constructions have been offered to the market which make possible the preparation of unique products. Such a fluorescent film can be superimposed directly over a retroreflective film, providing the combination of retroreflectivity and fluorescence in the same area without total sacrifice of either phenomenon. Although some compromises may be required when the single construction is used for both functions, the net effect is a material or construction that provides the desired combined characteristics of both daytime and nighttime visibility.
The concept of combining a fluorescent film over a retroreflective sheet is disclosed in U.S. Pat. No. 3,830,682, issued Aug. 20, 1974 to William P. Rowland. This technology is produced commercially by several firms and sold under trade names such as Reflexite (“Reflexite Corp), “RTC” (Avery International) and reflectorized “Stabrite” (SMV Technologies, Inc.) and Scotchlite Diamond Grade reflective sheet (Minnesota Mining and Manufacturing Co.).
The above examples of fluorescent and retroreflective products depend on incident light such as daylight (for fluorescent material) or an artificial light source such as an automobile headlamp (for retroreflective material) to provide visibility. The light must impinge on the face of the material to provide the desired daytime or nighttime visibility.
Nighttime visibility of a fluorescent film can be enhanced by placing a light source, such as an ordinary incandescent light bulb, behind a fluorescent film. The nighttime visibility of such a device can be increased by increasing the brightness of the light source or by increasing the transparency of the fluorescent film.
The development of electroluminescent light sources has provided a new degree of freedom in the preparation of backlighted fluorescent constructions. Electroluminescent lamps are characterized by low electric current consumption, good mechanical durability and the ability to be bent to conform to curved surfaces so long as the radius of curvature of the surface is greater than the curvature tolerance of the lamp. A further feature, which makes electroluminescent lamps particularly well suited for use with fluorescent films and constructions is that the light is emitted over a wide area rather than from a point source. This permits production of unique constructions, such as backlighted fluorescent films for both daytime and nighttime visibility, which may be considered as “active” rather than “passive” in their nighttime visibility modes. Conspicuity may be further improved by turning the lamp on and off periodically.
The backlighted fluorescent film provides the combination of a passive daytime device of high visibility with an active nighttime device of high visibility. The deficiency of such a device is that, in the event of a failure of the lamp, such as from interruption of the power source, the nighttime visibility is dramatically reduced and the device can no longer call attention to a hazard.
In accordance with this invention, there is provided a backlighted structure that combines the properties of fluorescence, retroreflectivity and electroluminescence in a single device whereby both daytime and nighttime visibility are markedly improved. Specifically, the invention is a composite structure comprising a source of electroluminescent light and, superimposed on said source, a translucent or transparent fluorescent film and, in close proximity thereto, a retroreflective film. The retroreflective film can be either superimposed on the light source or adjacent to it in the same plane.
The composite structure of this invention overcomes the deficiency of known electroluminescent-backed fluorescent films by providing retroreflectivity from incident light (e.g. automobile headlights) in the event of electrical power failure. The retroreflective film provides the device with a “fail safe” feature.
Since the retroreflective film does not depend on the light source for the effect that it produces, it need not be superimposed on the light source as is the fluorescent film. It can be superimposed on the light source if desired, either atop or under the fluorescent film, but it can also be placed adjacent to the fluorescent film and in substantially the same plane, e.g., in the presently used slow moving emblem. The retroreflective and fluorescent features of the film can also be combined into a single film, which is superimposed on the light source.
One embodiment of a structure according to this invention is the use of an electroluminescent light source behind the fluorescent center of a slow moving vehicle emblem. This structure provides the visibility of daytime fluorescence when the electroluminescent source provides minimal, if any, increase in visibility, with an active device which provides visibility when ambient lighting is not sufficient to provide the desired level of visibility. This structure is enhanced by the “fail-safe” feature of passive nighttime visibility from the retroreflective film, all in one device.
Another embodiment of a structure according to the invention is an elongated flexible structure that can be wrapped around a person or inanimate cylindrical surfaces such as construction zone barrels, trees or other such potential traffic hazards.
A significant advantage of such a construction is that the luminance of electroluminescent lamps tends to be low relative to incandescent lamps such as automobile headlights or even a good quality flashlight. The brightness of the retroreflective material under high intensity illumination, such as automobile headlights, can be far brighter than an electroluminescent lamp. Thus, the passive “fail safe” feature enhances the total visibility of the structure.
Retroreflective
Thorp Elizabeth M.
Thorp Stephen N.
Alexander W. Stanley
Robinson Ellis
LandOfFree
Backlighted fluorescent/retroreflective safety device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Backlighted fluorescent/retroreflective safety device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Backlighted fluorescent/retroreflective safety device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2516930