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LIGHT EMITTING DIODE ASSEMBLY FOR
USE AS AN AIRCRAFT POSITION LIGHT
FIELD OF THE INVENTION
This invention relates generally to an aircraft position light, and more specifically, to an aircraft position light formed by a light emitting diode assembly.
BACKGROUND OF THE INVENTION
Federal Aviation Administration Regulations require an aircraft to include position (or navigation) lights which help identify the attitude and position of the aircraft to nearby airborne and land-based entities. More specifically, airplanes are required to have left and right position lights consisting of a red light and a green light spaced laterally as far apart as practical, and installed on the airplane such that, when the airplane is in normal flying position, the red light is on the left side of the airplane and the green light is on the right side of the airplane. Additionally, airplanes must have a rear position light which is a white light mounted as far aft as practical on the tail or on each wingtip of the airplane.
Most airplane manufacturers comply with these regulations by installing position lights on airplanes that are implemented through the use of incandescent light sources. Alternatively, some position lights operate through the use of halogen lamps, which can have a longer life expectancy than incandescent lamps. These two types of light sources are often utilized because they can achieve the light distribution and light intensity required by Federal Aviation Regulations, promulgated by the Federal Aviation Administration (FAA). The FAA requires position lights to be of a minimum intensity at a multitude of displacement angles in both horizontal and vertical planes, as defined by an airplane's orientation. Regulations also require that position lights may not exceed specific light intensity values in certain horizontal and vertical positions. That is, within a position light's intended field of coverage, the FAA establishes minimum intensities only, and outside the intended field of coverage, the FAA establishes maximum intensities. In this manner, an airplane's attitude and position can easily be determined from multiple viewing angles while at the same time insuring that the lights are not too intense beyond the position lights' field of coverage to confuse or overpower other pilots, aircraft lights, and ground-based entities.
In addition to horizontal and vertical light intensity requirements, Federal Aviation Regulations also require each position light to be of a specific color based upon International Commission on Illumination chromaticity coordinates. Federal Aviation Regulations use these chromaticity coordinates to define a particular range of chromaticities or colors suitable for position lights, defined as aviation red, aviation green, and aviation white. The left position light must be aviation red, the right position light must be aviation green, and the rear position light must be aviation white.
Because most position lights use white incandescent and halogen light sources, position light manufacturers often achieve these particular color requirements through the use of light covers. Light covers are typically made of colored glass, and are placed in front of the light source. However, the use of these covers in flight conditions and with incandescent or halogen light sources can result in undesired consequences. For example, the transmittance of red and green glass covers is only about 20 percent. This results in the use of a relatively high powered lamp to meet light intensity requirements. High powered incandescent and
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halogen light sources emit a large amount of heat, which can shatter light covers made of glass. Furthermore, light covers can change color and transmittance with temperature, so that light intensity and color may fluctuate outside of specified
5 Federal Aviation Regulation requirements in response to temperature variations.
Because position lights must operate each time an aircraft is operating at night and because the lights can be difficult to access, especially on large commercial aircraft, it is
1° advantageous for position lights to have long life and to perform reliably. Unfortunately, however, position lights which use conventional incandescent and halogen lamps can typically burn out after 1000 to 2000 hours of operation. This can occur at an inopportune time, such as in-flight or
15 during a short layover on a runway. As a result, the lamps inside these position lights are frequently replaced while the airplane is on the tarmac. This frequent lamp replacement represents a high burden to airplane operators, maintenance crews, air traffic control, and any passenger or cargo on the
20 airplane.
In addition to costs associated with aircraft delays and required maintenance, conventional light sources used in combination with colored filtered glass require a large power supply and can be very heavy, both of which are undesirable
25 in airplane design. In this regard, incandescent and halogen position lights each require about 150-200 watts of power to produce intensity to meet FAA lighting requirements with suitable margin and redundancy. For example, 100-200 watt position lights are typically employed to provide twice the
30 light intensity required under Federal Aviation Regulations. With multiple position lights on each airplane, this high power requirement contributes to a large power load, which is undesirable because of the limitations of the generators on an aircraft. Furthermore, the heavy weight of incandescent
35 and halogen position lights and light covers make the lights difficult to install, and add to undesirable weight to the aircraft. Finally, (red and white) incandescent and halogen position lights emit light having a broad spectrum and relatively high amount of infrared energy, making the lights
40 interfere with night vision imaging systems (NVIS), such as employed in military and night rescue applications.
Accordingly, there is a continuing need for a reliable position light which results in a longer life and requires less
45 maintenance than conventional position lights, while achieving FAA light intensity and distribution requirements. Furthermore, it is desirable for such a light to have reduced power consumption and reduced manufacturing costs, to be lightweight, and to have a narrow spectral distribution and
5Q lower infrared energy than conventional position lights, thereby allowing for compatibility with night vision imaging systems.
SUMMARY OF THE INVENTION
55 The present invention utilizes an assembly of light emitting diodes (LEDs) to produce a position light which meets Federal Aviation Regulation lighting requirements while lasting longer than conventional incandescent and halogen position lights, and being relatively lighter, cheaper, and
60 requiring less power than conventional position lights. Colored LEDs may be chosen to comply with Federal Aviation Regulations lighting color requirements, obviating the need for colored light covers. Furthermore, the narrow spectral distribution of LEDs results in the additional benefit that the
65 position light of the present invention will interfere less with night vision imaging systems, as compared with conventional incandescent lamp based position lights.
According to one embodiment of the invention, a light emitting diode (LED) assembly for use as an aircraft position light includes a first plurality of circuit boards in electrical communication with a base circuit board. Each circuit board of the first plurality of circuit boards is parallel 5 to every other circuit board of the first plurality of circuit boards. In addition, each of the first plurality of circuit boards is disposed at the same acute angle relative to the base circuit board. The LED assembly also includes a second plurality of circuit boards in electrical communica- 10 tion with the base circuit board.
Each circuit board of the second plurality of circuit boards is disposed at an angle to every other circuit board of the second plurality of circuit boards. As such, and wherein the second plurality of circuit boards form a fan-shaped struc- :5 ture. In addition, the LED assembly includes a plurality of light emitting diodes electrically mounted to said first plurality of circuit boards and to said second plurality of circuit boards.
Each circuit board of the first plurality of circuit boards 20 and the second plurality of circuit boards in the LED assembly can be identical to every other circuit board of the first plurality of circuit boards and the second plurality of circuit boards, to facilitate manufacturing of the assembly, and to lower the costs associated with manufacture and 25 maintenance. The plurality of LEDs can include rows of LEDs, where each row of LEDs is electrically mounted to a single circuit board of the first plurality of circuit boards and the second plurality of circuit boards. Each circuit board, in turn, can be electrically and mechanically connected to the base circuit board at a first edge thereof In this embodiment, the LEDs are, in turn, connected to the circuit board at a second edge, substantially opposite the first edge.
Furthermore, each circuit board of the first plurality of 3J circuit boards and the second plurality of circuit boards can define an axis extending between the first and second edges of the circuit board that is disposed in a plane that is perpendicular to the base circuit board. In this embodiment, at least one LED of the plurality of LEDs can be connected 4Q to the circuit board so that the LED is aligned with the axis. Additionally, at least one LED may be located on the circuit board so that the LED is angled relative to the portions that cooperate to define an arched edge.
In one embodiment, the second edge of each circuit board 45 can include multiple edges. LEDs can abut the multiple edge portions so that the LEDs are oriented in different directions. For example, a number of LEDs could abut a center edge portion so that the LEDs are parallel to vertical axis defined by the circuit board. In addition, LEDs can be mounted upon 50 other edge portions that are angled relative to the center edge portion. For example, LEDs can be mounted at angles of ±12 and ±24° relative to the axis defined by the circuit board. Since the orientation of the LEDs is generally derived from the angle of the multiple edge portions with respect to the 55 axis defined by the circuit board, the proper angular orientation of the LEDs may be ensured by placement of the LEDs directly adjacent the edge portions of the circuit board.
The manner in which the LEDs and circuit boards can be 60 oriented on the base circuit board can be determined such that the position light meets and exceeds the lighting requirements of Federal Aviation Regulations. Using the known light distribution of a chosen LED, software operating on a computer may be utilized to determine the light 65 intensity at all points in space of a position light according to the present invention. The software may do so by being
programmed with conventional mathematical expressions which add known characteristics of light emission from multiple LEDs to produce a three dimensional plot of light intensity for a given assembly of LEDs. Therefore, through trial and error, the most effective embodiments of the present invention can be determined.
The LEDs can be chosen to meet the specific color requirements of Federal Aviation Regulations so that a colored light cover is not required to be placed in front of the position light. Furthermore, the LEDs chosen can have a narrow spectral distribution such that they interfere less with night vision imaging systems than conventional position lights.
According to another embodiment of the present invention, a light emitting diode (LED) assembly for use as an aircraft position light comprises a base circuit board and a plurality of light emitting diodes (LEDs) in electrical communication with the base circuit board. The LED assembly also includes a glass or optical plastic cover (lens) located adjacent the plurality of LEDs, where the optical cover includes a first optical section and a second optical section. The first optical section can include a first plurality of faces located on a side of the optical cover opposite the plurality of LEDs, wherein each face of the first plurality of faces is parallel to each other face of the first plurality of faces, and wherein each face of the first plurality of faces is positioned at the same acute angle relative to the base circuit board. The second optical section can include a second plurality of faces located on a side of the optical cover opposite the plurality of LEDs, wherein each face of the second plurality of faces is positioned at a different angle relative to the base circuit board than each other face of the second plurality of faces.
According to one aspect of the invention, each face of the first plurality of faces and each face of the second plurality of faces can correspond to a respective LED of the plurality of LEDs. Alternatively, each face of the first plurality of faces and each face of the second plurality of faces can correspond to at least one LED of the plurality of LEDs. Furthermore, like the first embodiment, each of the plurality of LEDs located within the position light assembly can be identical.
Other features and advantages of the present invention will become apparent to one skilled in the art upon examination of the following drawings and detailed description. It is intended that all such features and advantages be included herein within the scope of the present invention as defined by the appended claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a perspective view of a position light in accordance with an embodiment of the present invention.
FIG. 2 shows a perspective view of a circuit board of the position light shown in FIG. 1 in accordance with an embodiment of the present invention.
FIG. 3A shows a front view of the circuit board shown in FIG. 2 in accordance with an embodiment of the present invention.
FIG. 3B shows a front view of the circuit board shown in FIG. 2, in accordance with an embodiment of the invention, including light distribution vectors.
FIG. 4 shows a side view of the position light of FIG. 1 in accordance with an embodiment of the present invention.
FIG. 5A shows the Federal Aviation Regulation forward position light intensity multiplier requirements for horizon5
tal angles, and a graphical representation of the requirements with respect to a forward position light on the left wing of an airplane.
FIG. 5B shows the Federal Aviation Regulation forward position light intensity requirements for vertical angles, and 5 a graphical representation of the requirements with respect to a forward position light on the left wing of an airplane.
FIG. 6A shows a perspective view of a position light in accordance with another embodiment of the present invention 10
FIG. 6B shows a side view of the position light of FIG. 6A in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION OF THE
INVENTION 15
The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different 2Q forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements 2J throughout.
A forward position light according to an aspect of the present invention will first be introduced, including an assembly of LEDs mounted in various directions, followed by a more detailed description of the individual components 30 of the position light. Next, the use of various types of LEDs, including their orientation, effect on the orientation of components of the position light, and benefits, will be described. Finally, a software program will be described which allows a design engineer to tailor the forward position light to meet 35 predetermined requirements.
FIG. 1 shows a forward position light 10 in accordance with an embodiment of the present invention. The forward position light 10 includes a base circuit board 15 and a plurality of circuit boards that are electrically and mechani- 40 cally connected to the base circuit board 15. The forward position light 10 also includes a plurality of light emitting diodes (LEDs) 25 electrically and mechanically mounted upon each circuit board 20. Additionally, the forward position light 10 includes a power source 12 in electrical 45 communication with the base circuit board 15, which, in turn, provides power to the LEDs 25 which emit light in a multitude of directions relative to the base circuit board 15. The forward position light 10 can be mounted to an airplane by bolts, clamps, screws, adhesives, or by other suitable well 50 known means. One location of a forward position light 10, on an airplane wing, is illustrated in FIG. 5A.
Referring again to FIG. 1, the plurality of circuit boards can be connected to the base circuit board 15 at a variety of angles, so that at least one circuit board 20 is positioned at 55 an acute angle relative to a surface 17 of the base circuit board 15. The plurality of circuit boards can be mounted directly to the base circuit board 15 using any suitable technique known to those of skill in the art. Alternatively, the plurality of circuit boards can be mounted to the base circuit 60 board 15 using a mounting structure, as illustrated in FIG. 4. The purpose of angling or slanting at least one circuit board 20 and, more preferably, a plurality of circuit boards, with respect to the surface 17 is to achieve vertical (z-axis) light distribution in the directions of the y-axis and the -y-axis 65 (i.e., about the ±x-axis in the z-axis direction), as shown in FIG. 1. Similarly, the plurality of LEDs 25 connected to each
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individual circuit board 20 may be oriented at different angles to achieve vertical (z-axis) dispersal of light in the x-axis and the -x-axis directions (i.e., about the ±y-axis in the z-axis direction). For example, the LEDs 25 can be mounted on a circuit board 20 in a fan-like manner so that at least one LED 23 points toward the x-axis, and at least one LED 24 points toward the -x-axis. Therefore, through the combined orientations of the circuit boards and LEDs 25 located on each board 20, the forward position light 10 can emit light in multiple directions in the 3-dimensional space defined by the x, y and z-axes. In the embodiment of FIG. 1, 156 LEDs are mounted on 13 circuit boards, so that the LEDs are at 30 different angular orientations, a configuration which will be described in more detail with reference to FIG. 4, below. However, the position light 10 can include different numbers of circuit boards and different numbers of LEDs, if so desired.
One advantage of the position light 10 according to the present invention is that minimum position light intensities can be achieved with a light requiring less power than conventional incandescent and halogen position lights. For example, the embodiment shown in FIG. 1, utilizing 156 conventional LEDs and 13 circuit boards, requires approximately 20 watts of power, as compared to conventional light sources requiring approximately 200 watts of power to meet FAA position light intensity requirements with suitable margin and redundancy. Such a decrease in power is favorable to aircraft design, where efficient power management is critical. Furthermore, unlike conventional position lights, the current through LEDs should be regulated via current regulating integrated circuit chips so that voltage variation will not affect the light intensity of the position light 10 or the current through the LEDs. This current regulation may be required because LEDs utilize semiconductors that have large fluctuations in current based upon small changes in voltage, which can have deleterious effects on LED semiconductor material. The position light 10, and its individual components, will be described in more detail with respect to FIGS. 2-5.
FIG. 2 shows a perspective view of a circuit board 20 of the position light 10 shown in FIG. 1, in accordance with an embodiment of the present invention. According to one aspect of the invention each individual circuit board 20 of the position light 10 can be identical. Therefore, the circuit board 20 of FIG. 2 may be representative of any circuit board of the plurality of circuit boards included in the position light 10. However, it will be appreciated that each circuit board 20 can be unique in both shape and construction. Nonetheless, the use of identical circuit boards is preferred because identical circuit boards minimize the cost of manufacturing and maintaining the position light 10, and simplify its assembly and maintenance. Furthermore, the use of identical circuit boards can simplify the replacement of defective boards. The circuit board 20 can include a first edge 40 for electrical and mechanical connection with the base circuit board 15, and a second edge 44 substantially opposite the first edge 40. In addition, the circuit board can define an axis 35 that extends between the first and second edges 40, 44.
The axis 35 is disposed within a plane that is substantially perpendicular to the upper surface 17 of the base circuit board 15 once the circuit board is mounted thereon. A plurality of LEDs 25 are electrically and mechanically connected to the second edge 44 of the circuit board 20. In the embodiment of FIG. 2, the LEDs 25 are connected to the second edge 44 in a row formation.
The second edge 44 of the circuit board 20 typically includes a plurality of edge portions, as will be described in
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