Optic lens cell and illuminated signage having a cell array

Details Optic lens cell and illuminated signage having a cell array Optic lens cell and illuminated signage having a cell array

1999-09-27

2001-06-12

Cariaso, Alan (Department: 2875)

Illumination

Plural light sources

With modifier

C362S237000, C362S335000

Reexamination Certificate

active

06244727

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates generally to optical lenses, and more particularly, to a high efficiency optic lens cell with light emitting diodes for use in illuminated signs and signals.
BRIEF DESCRIPTION OF THE PRIOR ART
Illuminated signs and signals are commonly used in a variety of applications including traffic signal heads, pedestrian signal heads, blankout signs, lane control signal heads, portable road signs such as vehicle traffic control signs, pedestrian traffic control signs, message signs, and commercial advertising signs, and other portable and fixedly mounted signs. These lighting applications typically require a high intensity of light emission so that motorists, pedestrians, and other intended viewers will be made aware of the signage from a distance and may clearly discern the intended message even in bright daylight conditions.
To meet these high intensity of light requirements, incandescent lights have traditionally been used in such applications. There has been an increase in the use of light emitting diodes (“LEDs”) for illuminated signage, however, because of their desirable properties of high reliability and energy efficiency relative to incandescent lights. A drawback to using LEDs is that they provide a relatively low intensity, accordingly large numbers of LEDs must usually be employed to produce the desired intensity; some designs use 100 LEDs to produce the equivalent of a single incandescent light bulb.
There have been developed lens systems for use with LEDs which attempt to remedy this situation by providing lenses with specific geometric shapes that refract portions of the light transmitted therethrough to obtain a redistribution of light rays for increased intensity. For example, U.S. Pat. No. 5,636,057 to Dick et al. discloses a prismatic toroidal lens with two concentric solid lens portions that refract the light rays from a corresponding LED to form a modified divergent light beam. Also, U.S. Pat. No. 5,174,649 to Alston discloses a refractive lens having a hyperboloid incident light surface and an exit surface with facets configured to provide a desired light beam spread. Additionally, U.S. Pat. No. 5,833,355 to You et al. discloses a lens with an interior surface having a plurality of geometric horizontal bands to redirect light at specific angles.
The geometric refraction lenses of Dick et al., Alston, and You et al., all provide lenses with the benefit of redistributing light rays to achieve an increased utilization of the limited light output of LEDs. Each of the lens systems, however, retains certain optical losses related to the portion of the light emitted from each LED that is directed generally along and/or within a conical distribution about the central axis of light emission of the LED. These light rays need not be refracted as they are generally directed toward their intended viewing area and/or viewers. The lenses of Dick et al., Alston, and You et al., illustrate the conventional solution to providing a lens with no refraction and zero power which is to provide a generally flat lens (a “window pane”) through which light rays may be transmitted without substantial redistribution. Thus, in each of the prior art lenses, the light rays that need not be refracted are nevertheless transmitted through the lens and thereby incur optical losses because of the imperfect transmissibility of any known lens material, because of reflections at the interface of the air and the lens, and because of the accumulation of dirt and/or the like on the lens surface (See Dick et al. at
FIGS. 6-7
, Alston at
FIGS. 1A-1D
, and You et al. at FIG.
2
B).
These optical losses thereby reduce the intensity of the LED light rays transmitted through the lens. The efficiency of conventional optical materials that are economically practical for such lighting applications is typical limited to about 75%, so that typically 25% or more of the portion of the LED light output that is directed by each LED toward its intended viewing area and/or viewers is lost.
There are additionally known to be lenses for use with incandescent light bulbs that have a band, slot, or other central lens portion defined therein. U.S. Pat. No. 3,137,449 to Lenz discloses a central circular portion defined in a lens with a convex surface, though only the lens surface is convex and a solid body lens is not provided. Additionally, U.S. Pat. No. 1,995,816 to Adler, Jr. discloses a lens with a band comprised of a multitude of prisms for accentuating and directing the light output. Furthermore, U.S. Pat. No. Des. 87,501 to Adler, Jr. and U.S. Pat. No. Des. 92,641 to Adler, Jr. each disclose an ornamental design for a traffic signal having lenses with bands. Each of these lenses has a generally central portion provided as a solid material that is different from the outer portions of the lens and that focuses, diffuses, or otherwise refracts the light transmitted therethrough. Thus, the central portions of each of these lenses cause optical losses to the light rays transmitted therethrough similar to the lenses of Dick et al., Alston, and You et al. described above.
Accordingly, what is needed but not found in the prior art is a lens system for use with LEDs in illuminated signs and signals that refracts certain lights rays from an undesirable direction to a desirable direction and that allows light rays directed toward their intended viewing area and/or viewer to be transmitted through the lens without being refracted and with little or no optical losses.
SUMMARY OF THE INVENTION
Generally described, the present invention provides an optic lens cell for an illuminated sign or signal, the cell having at least one and preferably a plurality of light sources each with a central axis of light emission. The cell also has at least one lens spaced apart from the light source, the lens having at least one and preferably a plurality of convex portions each with an aperture that has a central axis generally parallel to the light source central axis. The light source and lens are mounted on a board. The light source is capable of being electrically connected to a power source such as but not limited to 120/240VAC, a battery, a photovoltaic cell, a generator, or the like. When the light source is powered, a portion of the light rays emitted from each LED are redirected by the lens convex portions and a portion of the emitted light rays are allowed to pass through the apertures, resulting in an overall distribution of light that is highly efficient.
In a preferred embodiment of the present invention, the light sources are provided by LEDs with each LED axis and aperture axis being generally collinear. Also, the lens convex portions each have a central axis and the aperture is arranged in the lens so that each aperture central axis is generally collinear with each lens central axis. Each lens convex portion is generally convex about two axes and each aperture is cylindrical. The LEDs are mounted on a circuit board and wired together so they operate as one. A plurality of the cells may be combined together into an array and contained by a housing to form a sign or signal. An electric control may be provided with the housing or remotely located for timing and other control functions of the cells. Each cell is capable of being independently operated for forming various lighted patterns as may be desired for traffic lights, portable roadside lights, commercial signs and the like.
In a first alternative embodiment of the lens, the convex portion is convex about one axis and the aperture is generally cylindrical. In a second alternative embodiment of the lens, the convex portion is convex about one axis and the aperture is in the form of a slot. In a third alternative embodiment of the lens, the convex portion is convex about two axes and the aperture is in the form of a slot. In a fourth alternative embodiment of the lens, the convex portion is convex about two axes and the aperture is in the general shape of a frustum. In a fifth alternative embodiment of the lens, the convex portion i

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