Illuminated sign

Details Illuminated sign Illuminated sign

1998-11-25

2001-03-13

Melius, Terry Lee (Department: 3628)

Card, picture, or sign exhibiting

Illuminated sign

Lamp box

C362S812000

Reexamination Certificate

active

06199310

ABSTRACT:

TECHNICAL FIELD
This invention relates to an improved illuminated sign, and, more specifically to an improved neon grid sign and method for designing a neon grid sign that can be read from a variety of angles without a visible presence of undesirable streaks in the sign lettering illumination.
BACKGROUND OF THE INVENTION
Illuminated signs are used throughout the world to convey information to passers-by. Neon is often chosen for such illuminated signs because of the distinctive, brilliant color it emits. Traditionally, neon has been used in the form where tubing is bent into the shape of a word. Manufacture of this type of sign requires the frequently costly services of a skilled glass tube bender. Such signs are also limited in that once they have been created at considerable expense, they cannot be modified.
Referring now to
FIGS. 1 and 2
, there are depicted a partial-cutaway plan view and a cross-sectional side view of an illuminated sign, known as a neon grid sign, described generally in several early U.S. patents (for example, U.S. Pat. No. 1,813,759 to Thomas Peters, U.S. Pat. No. 2,080,679 to E. D. Vissing, U.S. Pat. No. 2,094,436 to H. R. VanDeventer et al., U.S. Pat. No. 2,046,044 to R. A. Vissing, and U.S. Pat. No. 2,118,385 to J. J. Shively). Such signs are not prevalent in commerce today. Sign
10
comprises essentially a sign frame
14
having a width “W” in which are located lengthwise sections of luminous tubing
12
parallel to the width and providing illumination. The sign frame is covered by a sign face
18
having transparent letters
11
outlined by an opaque background
13
.
Luminous tubing
12
has a small diameter relative to the sign box width, and thus may be bent in alternating 180-degree curves into an S-shaped pattern with lengthwise sections
15
between curves
42
to provide illumination over the complete sign width, as shown in FIG.
1
. The luminous tubing
12
is electrically attached to an electrical transformer
16
. To provide a uniform appearance of light instead of a series of lines, the tubing may be mounted within curved, reflective channels
20
that have a mirrored surface.
A neon grid signs offers an advantage over signs comprising merely a neon tube bent into the shape of a word, in that a single sign frame
14
may be used with multiple or modifiable sign faces
18
to change the text of the sign as desired. The neon grid signs as described in the aforementioned references have a disadvantage, however, in that from certain angles between the viewer and the sign, the light shining through the letters forms a streaked pattern, as depicted in
FIG. 3
, that make the message on the sign difficult to read. Depending upon the quality of the reflectors behind the tubing, this streaked pattern may appear as a series of dark lines, or may comprise stripes of greater and lesser brightness.
The unilluminated ridges
22
between reflective channels
20
may contribute to the streaked pattern. A key factor in the creation of the streaked pattern is that the curvature of the reflector
20
may not reflect light back to the viewer
30
from the tubing
12
at certain viewing angles &ggr;, as shown in
FIG. 4
, but instead reflects the lesser light coming from the direction of the viewer.
Some of the references disclosed above discuss ways to address this problem. Patent '759 describes a neon grid sign where the grid of neon tubing stands alone as the source of light, and where the pattern produced by either a single grid of one color, or multiple grids of more than one color is part of the effect desired. In such a pattern, the changes in color or light intensity are desired, so the issue of uniform light is not addressed.
Patent '679 describes the presence of metallic reflectors similar to reflectors
20
that reflect the light from the neon tubing in what is “practically a sheet of light”. Patent '679 also describes, however, some presence of dark lines or reduced light reflection efficiency associated with each reflector embodiment. Significantly, patent '679 also refers to means for angling the sign to enable the sign to be more easily read when the observer is above or below the sign, implying that the illumination quality may suffer when the sign is at a vertical angle from the viewer.
Patent '436 purports to provide a sheet of neon “substantially free of the objectionable streaks and of uniform over-all brilliancy”; however, the reference provides no detail regarding the geometry of the reflectors, so that this claim can be verified. Additionally, the patent claims adjustable means for tilting the sign face at various angles, again suggesting that the sign may have required angular adjustment to facilitate streak-free viewing at certain angles.
Patent '044 describes an improvement in the form of a gap in the reflector that was necessary to prevent electrical buzzing from occurring as a result of current leakage from the bulbs to the metal reflectors.
Patent '385 describes a neon grid sign that uses a sheet of ribbed glass or other diffusion plate to help eliminate the streaked pattern. Such a diffusion plate, however, necessarily also dims the brightness of the light visible to the viewer. Thus, some of the color and brilliance that makes neon a desirable light source may be lost.
The continued pursuit of a neon grid sign free of the undesirable streaked pattern in the 1930's and the dearth of such signs in commercial use today are testimony to the desirability and elusive nature of a sign that eliminates the streaked pattern. The present invention provides a neon grid sign and method for designing such a sign that optimizes the dimensional properties of the reflector channels to eliminate, without a diffusion plate, the streaked pattern even when the sign is viewed from a vertical angle, the reflector channel design being adaptable to the largest viewing angle of the intended viewer.
SUMMARY OF THE INVENTION
In accordance with this invention, there is provided an illuminated grid sign designed to be viewed at a maximum viewing angle (&agr;) from a horizontal line of sight of an observer, the sign comprising:
a frame having a width;
a partially transparent face supported thereon;
a plurality of lengthwise sections of luminous tubing mounted in the frame and having a tubing inside radius (r) and an inside surface having a reflector-closest edge, and;
a plurality of concavely-curved, reflective channels each having an angle of wrap (&bgr;) and a concave surface having a tubing-closest edge positioned at a minimum distance (d) from the tubing inner surface reflector-closest edge;
wherein the improvement comprises each channel having a substantially semi-cylindrical shape with a radius of curvature (R) approximately equal to 120% of r×(1+1/(sin &agr;))+d, or less.
The invention also comprises a method for designing an illuminated grid sign having illuminated tubing and a plurality of reflective channels therein, the method comprising:
determining a maximum viewing angle (&agr;) from a horizontal line of sight of an observer to the sign;
selecting the illuminated tubing, said tubing having an inside radius (r);
determining a minimum distance (d) between the tubing inside radius and the reflective channel adjacent thereto; and
designing the reflective channels to be substantially semi-cylindrical in shape with a radius of curvature (R) approximately equal to 120% of r×(1+1/(sin &agr;))+d, or less.
The method may further comprise selecting an angle of wrap (&bgr;), no greater than 180 degrees, for the reflective channels that minimizes visible streaks of brighter and less-brighter regions in the sign when viewed from the maximum viewing angle (&agr;), or less.


REFERENCES:
patent: 1813759 (1931-07-01), Peters
patent: 2046044 (1936-06-01), Vissing
patent: 2057064 (1936-10-01), Shively et al.
patent: 2080679 (1937-05-01), Vissing
patent: 2090989 (1937-08-01), Van Deventer et al.
patent: 2094436 (1937-09-01), Van Deventer et al.
patent: 2118385 (1938-05-01), Shively
patent:

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