The present application generally relates to retroviewers for use in viewing one or more retroreflective articles.
Retroreflective materials are characterized by the ability to redirect light incident on the material back toward the originating light source. This property has led to the widespread use of retroreflective sheeting for a variety of traffic and personal safety uses. Retroreflective sheeting is commonly employed in a variety of articles, for example, road signs, barricades, license plates, pavement markers and marking tape, as well as retroreflective tapes for vehicles and clothing.
It is often desirable to assess the retroreflectivity of articles including retroreflective sheeting in order to ensure their compliance with safety guidelines. Because retroreflective sheeting made by differing sheeting manufacturers or distributors often exhibits differing retroreflectivity at given angles, it is also desirable to compare the retroreflectivity of samples of retroreflective sheeting and/or articles including retroreflective sheeting. Existing retroviewers capable of visually assessing retroreflectivity are described in U.S. Pat. No. 3,767,291 (issued Oct. 23, 1973) and U.S. Pat. No. 3,832,038 (issued Aug. 27, 1974), both of which were assigned to the assignee of the present application. These patents describe, respectively, a table-top and handheld retroviewer capable of verifying a document having a retroreflective image bearing layer which is substantially transparent under diffuse light viewing conditions to provide viewing of images on an underlying surface.
The inventor of the present application recognized that the existing retroviewers had certain drawbacks. One such drawback is their production of a virtual image having an area of less than 0.5 square inch. In some instances, different sized, and often larger, virtual images may be desired. Another drawback is that existing retroviewers have an angle of divergence from the illumination axis of from 0.2° to about 2°. In some instances, different angles of divergence may be desired. Further, existing retroviewers are largely used to detect retroreflectivity at a distance of between about 0.5 foot to about 2 feet. This distance range is at least partially dependent on the construction of the existing retroviewers and their inclusion of beam splitters and small, low-intensity lights.
In some instances, detection of retroreflectivity at different distances may be desired. For example, when viewing retroreflective sheeting for use in or when viewing a license plate, detection of retroreflectivity at a distance of between about 5 feet and about 100 feet, for example, may be desired. Existing retroviewers are inadequate for visual detection of retroreflectivity at this distance.
Consequently, the inventor of the present application designed various retroviewers capable of detecting retroreflectivity at multiple observation angles and greater viewing distances. Retroviewers of the present application facilitate a comparison of retroreflective materials under multiple scenarios simulating real world viewing conditions that are critical in the use of vehicle license plates, traffic signs, and the like. For example, both small observation angles (0.1 degrees to about 1.0 degrees, more preferably between about 0.2 degrees and about 0.4 degrees) for long-distance safety scenarios and larger observation angles (between about 1.1 degrees and greater than 2 degrees) for license plate reading scenarios can be created using the retroviewers of the present application. The user can choose retroviewer dimensions and angles suitable for the desired applications (e.g., demonstration of retroreflectivity in an office environment).
In one embodiment of the present application, a retroviewer for use in viewing a retroreflective article at a distance of between about 5 feet and about 100 feet includes (1) a housing portion including a body that forms a handle, the housing portion capable of holding at least one light source; and (2) a viewing portion adjacent to the housing portion and including a viewing passageway having a longitudinal axis that perpendicularly intersects a longitudinal axis of the body.
In another embodiment of the present application, a retroviewer for use in viewing a retroreflective article includes (1) a housing portion including a tubular body that (a) forms a handle and (b) that is capable of holding a first light source capable of emitting light along a first illumination axis and (c) that is capable of holding a second light source capable of emitting light along a second illumination axis, wherein the first and second light sources positioned perpendicular to a longitudinal axis of the tubular body and separated by a distance d; and (2) a viewing portion adjacent to the housing portion and including a viewing passageway having a longitudinal axis that perpendicularly intersects the longitudinal axis of the tubular body, wherein the viewing portion further includes an eyepiece.
In another embodiment of the present application, an adjustable retroviewer for use in viewing a retroreflective article includes: (1) a housing portion including a body that forms a handle and that is capable of holding a light source capable of emitting light along a first illumination axis; and (2) a viewing portion adjacent to the housing portion and including a viewing passageway having a longitudinal axis that perpendicularly intersects the longitudinal axis of the body, the viewing portion further including an eyepiece and a flange into which body may be fitted. In this embodiment, the distance between the viewing portion and the light source can be altered by movement of the body along its longitudinal axis into the flange.
Retroviewers of the present application are capable of assessing retroreflectivity of retroreflective articles, including, but not limited to, retroreflective sheeting, signs, license plates, documents, and the like. At least some of the retroviewers are handheld in that they can be held up to the user's eye by the user's hand.
One exemplary embodiment of a retroviewer of the present application is shown in
Housing portion 102 includes an upper housing portion 130 and a lower housing portion 132, each of which are connected to body 104 by one or more connection means 134 such as, for example, the T-joints shown in
Those of skill in the art will appreciate that many changes can be made to the specific embodiment shown in
A cross-sectional view of one exemplary embodiment of an adjustable retroviewer 300 including only one light source 140 is shown in
Retroviewers of the present application are particularly useful for verification of retroreflective articles that are viewed at a distance of between about 5 feet and 100 feet, more preferably between about 10 feet and about 50 feet, and most preferably between about 15 feet and about 30 feet. One such retroreflective article is a license plate or a sample of license plate sheeting.
The viewing position defined by eyepiece 108 is spaced approximately the same distance from the retroreflective article as the light source(s) 130 and 132. Further, in at least some preferred embodiments, eyepiece 108 is secured to housing portion 102 to position the user's eye along a viewing axis at a slight downward angle of about 0.1° to about 1.5°, more preferably between about 0.5° to 1°.
As shown in
In at least some embodiments of the adjustable retroviewer, the user can change (1) the distance between the retroviewer and the retroreflective article and (2) the distance between the eyepiece and the single light source to change the observation angle. As was stated above, moving the retroviewer closer to the retroreflective article will create larger observation angles and moving the retroviewer farther from the retroreflective article will create smaller observation angles. In at least some embodiments of the adjustable retroviewer, two light sources are not required because any observation angle is possible between the minimum and maximum slot positions.
The retroviewers of the present application allow the viewer to visually detect retroreflectivity and retroluminance (the product of retroillumination and retroreflectance).
A prototype of the retroviewer shown in
The recitation of all numerical ranges by endpoint is meant to include all numbers subsumed within the range (i.e., the range 1 to 10 includes, for example, 1, 1.5, 3.33, and 10).
Those having skill in the art will appreciate that many changes may be made to the details of the above-described embodiments and implementations without departing from the underlying principles thereof. Further, various modifications and alterations of the embodiments and implementations described and shown in the present application will become apparent to those skilled in the art without departing from the spirit and scope of the application. The scope of the present application should, therefore, be determined only by the following claims.
This application claims the benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 61/243, 871 filed Sep. 18, 2009.
Number | Date | Country | |
---|---|---|---|
61243871 | Sep 2009 | US |