1. Field of the Invention
The present invention relates generally to signaling devices and more particularly to an improved light emitting diode signaling device and a method of providing an indication using the same.
2. Background Information
Light emitting diodes (LEDs) are replacing incandescent bulbs in various types of signaling devices such as, for example and without limitation, traffic signals, railroad crossing signals, and railroad wayside signals. An LED signaling device (i.e., a signaling device incorporating LEDs as an indication source) consumes less power, provides increased reliability, and requires less maintenance than a comparable incandescent signaling device (i.e., a signaling device incorporating an incandescent bulb as an indication source).
Older generation LEDs used in LED signaling devices, however, have several limitations. For example, the luminous output intensity of individual older generation LEDs is fairly low. As a result, dozens and sometimes hundreds of LEDs must be employed to generate the minimum luminous output intensity for certain signaling devices. The use of large numbers of LEDs, however, increases the manufacturing, operating, and maintenance costs of the LED signaling device. Additionally, the amount of space needed to accommodate the large number of LEDs make retrofitting some existing incandescent signaling devices prohibitive.
LED technology has continued to improve. For instance, newer generation LEDs are capable of generating a higher luminous output with lower power consumption than older generation LEDs. Thus when employed in a signaling device, fewer new generation LEDs are needed to meet the minimum luminous output intensity requirements for the signaling device. The use of fewer LEDs, however, may cause uniformity problems. Specifically, the use of fewer LEDs may undesirably increase the potential for viewing one or more of the LEDs as an individual point source and/or may undesirably increase the potential of creating shadows. A typical uniformity requirement may demand that the ratio between the greatest luminance LED and least luminance LED in the signaling device must not exceed 5:1 when measured over average areas of 500 mm.
Thus, a need exists for an improved LED signaling device which employs fewer LEDs, which meets or exceeds minimum luminous output intensity requirements, and which meets or exceeds minimum uniformity requirements. A method of providing an indication using the improved LED signaling device is also needed.
These needs and others are met by the present invention, which is directed to an improved LED signaling device. The improved LED signaling device employs a number of LEDs arranged in a specific pattern. At least some of the LEDs are received in a corresponding reflective cavity with an associated output angle. The LED signaling device also employs first and second lenses. The first lens collects the light emitted by the LEDs and disperses the light such that the second lens is flooded. The second lens collects the light dispersed by the first lens and collimates the light. The type of LEDs used, their specific pattern, the specific output angles of their corresponding reflective cavities, and the combination of the first and second lenses insure that the LED signaling device meets or exceeds the minimum luminous output intensity requirements and uniformity requirements.
As another aspect of the invention, an improved LED signaling device comprises a back plate, a circuit board, a reflector, a first lens, and a second lens. The circuit board is coupled to the back plate. The circuit board has a first surface with a number of LEDs arranged in a pattern thereon. The reflector is coupled to at least one of the back plate and the circuit board and has a number of reflective cavities, each with an associated output angle. At least some of the reflective cavities are arranged in the pattern and are structured to receive at least one of the LEDs therein. The first lens is coupled to at least one of the back plate, the circuit board, and the reflector and is located a first distance from the first surface. The second lens is coupled to at least one of the back plate, the circuit board, the reflector, and the first lens, and is located a second distance from the first surface.
As another aspect of the invention, a method for providing an indication with an LED signaling device comprises activating a number of LEDs to produce a plurality of light rays, wherein the LEDs are arranged in a pattern, and wherein each of at least some of the LEDs are associated with a respective one of a plurality of reflective cavities each having an associated output angle, dispersing the light rays with a first lens, and collimating the light rays dispersed by the first lens with a second lens.
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
a is a specification table illustrating the luminous output intensity for a 6″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for an 8″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for a 12″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for a 6″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for a 6″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for a 6″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for a 6″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for an 8″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for an 8″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for an 8″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
a is a specification table illustrating the luminous output intensity for an 8″ LED signaling device employing the LED pattern shown in
b is a table illustrating the percentage of the minimum luminous output intensity requirement for the specification table of
Directional phrases used herein, such as, for example, left, right, clockwise, counterclockwise, top, bottom, up, down, and derivatives thereof, relate to the orientation of the elements shown in the drawings and are not limiting upon the claims unless expressly recited therein.
As employed herein, the term “number” shall mean one or more than one and the singular form of “a”, “an”, and “the” include plural referents unless the context clearly indicates otherwise.
As employed herein, the statement that two or more parts are “connected” or “coupled” together shall mean that the parts are joined together either directly or joined together through one or more intermediate parts. Further, as employed herein, the statement that two or more parts are “attached” shall mean that the parts are joined together directly.
Referring to
In the current embodiment, the back plate 3 includes a rear wall 3a that is generally circular in shape. A side wall 3b extends axially from the outer circumference of the rear wall 3a and a flange 3c extends radial from the opposite end of the side wall 3b. The flange 3c includes a number of slotted posts 13 spaced about an inner circumference and a number of clips 12 spaced about an outer circumference. In the current embodiment, the back plate 3 is constructed of injection molded nylon having a spun aluminum heat sink molded therein. The heat sink may be molded into one, or a combination of, the rear wall 3a, the side wall 3b, and the flange 3c. It should be noted that other materials and or arrangements may be utilized for the back plate 3 and/or heat sink while remaining within the scope of the present invention.
In the current embodiment, the circuit board 4 is coupled to the rear wall 3a of back plate 3, for example, using a number of screws 16 or other fasteners. The circuit board 4 has a surface 4a with a number of LEDs 5 arranged in a pattern thereon. For example in the current embodiment, eight LEDs 5 are arranged in a pattern relative to a central axis 21 running through the LED signaling device 1. Although other LEDs 5 may be used, the LEDs 5 used in the current embodiment are red LUXEON® K2 high-powered LEDs manufactured by Lumileds Lighting (e.g., part number LXK2-PD12-S00). These LEDs 5 are rated to produce approximately 55 lumens at approximately 350 mA. The circuit board 4 includes at least one electrical terminal structured to receive an electrical signal for powering the LEDs 5. For instance in the current embodiment, an external conductor (not shown) for supplying a signal may be connected to a first end 17a of a stud 17 which passes through the rear wall 3a of base plate 3. The external conductor may be secured to the first end 17a of the stud 17 via a combination of washers 19 and nuts 20. An O-ring 18 may be included to prevent moisture, etc. from entering the LED signal device. A second end 17b of the stud 17 is electrically connected to the circuit board 4.
The reflector 6 is coupled to at least one of the back plate 3 and, as illustrated in
The first fresnel lens 8 is coupled to at least one of the back plate 3, the circuit board 4, and the reflector 6. In the current embodiment, the first fresnel lens 8 includes a number of arms 15 radially extending from the outer circumference thereof. The end of each arm 15 includes a tab 14 which is structured to engage a corresponding slot in one of the slotted posts 13 on the base plate 3. When the LED signaling device 1 is assembled, the first fresnel lens 8 is located a distance from the surface 4a of the circuit board 4. In the current embodiment for example, the first fresnel lens 8 is located approximately 28.5 mm from surface 4a. Although the first lens 8 is discussed as being a fresnel lens, it is contemplated that another type of lens may be used while remaining within the scope of the present invention.
The second fresnel lens 9 is coupled to at least one of the back plate 3, the circuit board 4, the reflector 6, and the first fresnel lens 8. In the current embodiment, the second fresnel lens 9 is incorporated into a cover 10. The cover 10 includes a base ring 11 having a number of notches 11a therein. The second fresnel lens 9 is spaced apart from the base ring 11 by a side wall 11b. The notches 11a are structured to engage corresponding clips 12 located on the back plate 3. Cover 10 is structured to form a “snap-fit” with base plate 3 when the notches 11a are engaged with their corresponding clips 12. One or more O-rings 22 may be provided to promote a proper seal such that water, dirt, and other debris cannot enter into the LED signaling device 1. When the LED signaling device 1 is assembled, the second fresnel lens 9 is located a distance from the surface 4a of the circuit board 4. In the current embodiment for example, the second fresnel lens 9 is located approximately 60 mm from surface 4a. Although the second lens 9 is discussed as being a fresnel lens, it is contemplated that another type of lens may be used while remaining within the scope of the present invention.
In the current embodiment, the LEDs 5, the LED pattern, the reflective cavities 7, and the dual lenses cooperate such that the LED signaling device 1 meets or exceeds minimum luminous output intensity requirements and uniformity requirements. More specifically, the pattern of the LEDs, the output angles of the reflective cavities 7, and the location of the first fresnel lens 8 relative to the surface 4a of the circuit board 4, are chosen such that substantially the entire surface of the first fresnel lens 8 is illuminated by the light emitted by the LEDs 5. The first fresnel lens 8 collects the light emitted by the LEDs 5 and disperses the light. The design of the first fresnel lens 8 and the location of the second fresnel lens 9 relative to the surface 4a (and thus, the distance between the first and second fresnel lens) is chosen such that the entire surface of the second fresnel lens 9 is flooded. The second fresnel lens 9 collects the light dispersed by the first fresnel lens 8 and collimates the light.
By dispersing the light emitted by the LEDs with the first fresnel lens 8 such that the second fresnel lens 9 is flooded, the uniformity requirements are met (i.e., the potential for viewing one or more of the LEDs 5 as an individual point source and/or the potential of creating undesirable shadows is eliminated). For example, the ratio between the greatest luminous LED and least luminous LED in the signaling device does not exceed 5:1 when measured over average areas of 500 mm. Additionally, by collimating the light with the second fresnel lens 9, the light is “focused” such that the minimum luminous output intensity requirements are met (as will be discussed in more detail in conjunction with
The pattern illustrated in
The pattern illustrated in
Table 1 lists the x, y, and z coordinates (measured in millimeters) for each LED 5, as well as the output angle of the reflective cavity 7 associated with each LED, for the pattern illustrated in
Table 2 lists the x, y, and z coordinates (measured in millimeters) for each LED 5, as well as the output angle of the reflective cavity 7 associated with each LED, for the pattern illustrated in
a illustrates the luminous output intensity and
a illustrates the luminous output intensity and
a illustrates the luminous output intensity and
The pattern illustrated in
Table 3 lists the x, y, and z coordinates (measured in millimeters) for each LED 5, as well as the output angle of the reflective cavity 7 associated with each LED, for the pattern illustrated in
As illustrated in
a, 12a, 13a, and 14a are specification tables illustrating the luminous output intensity for the LED signaling device of
The pattern illustrated in
Table 4 lists the x, y, and z coordinates (measured in millimeters) for each LED 5, as well as the output angle of the reflective cavity 7 associated with each LED, for the pattern illustrated in
As discussed above, the various colored LEDs 5 (for example and without limitation, red, yellow, green, and white LUXEON® K2 high-powered LEDs manufactured by Lumileds Lighting) may be used in the current embodiment. The pattern illustrated in
a, 17a, 18a, and 19a are specification tables illustrating the luminous output intensity for the LED signaling device of
While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of the invention which is to be given the full breadth of the claims appended and any and all equivalents thereof.
Number | Name | Date | Kind |
---|---|---|---|
1525841 | Wells et al. | Feb 1925 | A |
1548984 | Day | Aug 1925 | A |
1785694 | Day | Dec 1930 | A |
4654629 | Bezos et al. | Mar 1987 | A |
4700278 | Chew | Oct 1987 | A |
4972302 | Masuyama et al. | Nov 1990 | A |
5128848 | Enders et al. | Jul 1992 | A |
5697584 | Chew | Dec 1997 | A |
5735492 | Pace | Apr 1998 | A |
5947587 | Keuper et al. | Sep 1999 | A |
6019493 | Kuo et al. | Feb 2000 | A |
6283613 | Schaffer | Sep 2001 | B1 |
6435459 | Sanderson et al. | Aug 2002 | B1 |
6509840 | Martineau | Jan 2003 | B2 |
6616299 | Martineau | Sep 2003 | B2 |
6642666 | St. Germain | Nov 2003 | B1 |
6667623 | Bourgault et al. | Dec 2003 | B2 |
6717526 | Martineau et al. | Apr 2004 | B2 |
6731222 | Martineau | May 2004 | B2 |
6851833 | Simon | Feb 2005 | B1 |
6905227 | Wu | Jun 2005 | B2 |
6955449 | Martineau | Oct 2005 | B2 |
20020181232 | Martineau | Dec 2002 | A1 |
20040252520 | Martineau et al. | Dec 2004 | A1 |
Number | Date | Country | |
---|---|---|---|
20070274070 A1 | Nov 2007 | US |