Patent Application
20070115655
The present invention relates to a new and useful lighting system that is particularly useful as a floodlighting system for a space such as the deck of a ship, and to a new and useful optical projection structure for a lighting system.
Current deck lamps use incandescent lamps with reflectors. While these systems provide illumination over a broad area, they are deficient in a number of ways. One of the primary issues is that they do not uniformly illuminate the deck. Directly in front of each lamp is a bright spot and the brightness decreases significantly as the distance in increased. In addition, incandescent lamps have limited lifetimes so regular maintenance must be done frequently and the risk of having a deck lamp fail is undesirably high.
An additional problem with current deck lamps is that too much light is directed off of the deck. If the deck lamp is being used on a military ship, any light that misses the deck contributes to the ship's visual signature and makes it easier to see. Finally, current deck lamps produce a significant amount of light that can be detected by night vision goggles (NVGs) which makes NVGs difficult to use. Attempts have been made to insert filters over the deck lamps to allow pilots landing on ships to use NVGs while personnel on the ship still have an adequate level of illumination, but the results are inadequate.
In the applicant's experience, illuminating a ship deck, particularly a ship deck that aircraft may be taking off from and landing on at all hours, presents a number of challenges. There is a need to illuminate a volume space on the ships deck in a way that enables pilots to take off and land at all hours, without interference with the night vision goggles they often use in such maneuvers. In addition, a lighting system needs to be optically effective, as well as cost effective. Moreover, the lighting system should project significant light to a predetermined volume space (e.g. the center of the deck), and in a way that is compatible with pilot's night vision goggles.
The present invention provides a new and useful lighting system that is designed to address the foregoing issues, and to a new and useful optical projection structure for such a lighting system. The lighting system of the invention is designed to be particularly useful as a lighting system for a deck (e.g. a ship deck), where pilots taking off from or landing on the deck often use night vision goggles. Moreover, the principles of the present invention are also intended to be useful in various other types of applications. The new optical projection structure is particularly useful in the lighting system of the present invention, and may also be useful in other types of lighting systems.
According to the present invention, a lighting system comprises at least a pair of lighting subsystems that project light to a volume space with different spatial distributions. One subsystem projects light to the volume space with a predetermined spatial distribution, and the other lighting subsystem projects light to the volume space with a different spatial distribution, in a manner that effectively supplements the projected light from the first subsystem, so as to provide a lighting system that effectively illuminates the entire volume space.
In one preferred application of the lighting system of the present invention, the lighting system is designed to illuminate the deck of a ship such as a carrier, and from which aircraft land and take off. The system provides a pair of lighting subsystems with different spatial distributions for illuminating the deck, in accordance with the foregoing principles.
Moreover, the system is designed to be particularly compatible with the optical capabilities of night vision goggles. The system is designed to substantially filter out light in a predetermined wavelength band that is “out of band” of night vision goggles (i.e. the wavelength band at which night vision goggles operate), so that the projected light effectively illuminates the deck, and does not interfere with the vision of pilots who are using night vision goggles.
In addition, the lighting system of the present invention is designed to be optically efficient, provide uniform illumination, and be friendly to NVGs and to be cost effective.
Still further, the principles of the present invention, while particularly useful in illuminating a ship deck, can also be used in other types of environments where illumination of a volume space in a manner that also minimizes projection of light in a wavelength band that can have adverse effect for the system is desirable. For example, street lighting systems that also need to minimize light pollution (e.g. because of optical devices in an area of interest) can benefit from the principles of the present invention.
Furthermore, the present invention provides a new and useful optical projection structure, that is particularly useful in projecting light from a source (e.g. an array of light emitting diodes [“LEDs”]) to a volume space, while minimizing the overall size of the projection structure, and maintaining good projection efficiency. The light projection structure comprises a curved reflector segment and a refractor. The curved reflector segment and refractor are in a predetermined light collection relationship to each other, and the source has a predetermined location and angular relation to the curved reflector segment and the refractor that is at least partially based on the focal points of the curved reflector segment and refractor and the light collection relationship of the curved reflector segment and the refractor.
Other features of the present invention will become further apparent from the following detailed description and the accompanying drawings.
a is a three dimensional view of an individual light producing component in the second lighting subsystem;
As discussed above, the present invention provides a new and useful lighting system that is particularly useful as a lighting system for a deck (e.g. a ship deck), and to an optical projection structure that is particularly useful in such a system. The principles of the present invention are described herein in connection with a ship deck lighting system that is designed to illuminate the center of the deck, without interference with pilots' night vision goggles. However, from that description, the manner in which the principles of the present invention can be used with various types of lighting systems will be apparent to those in the art.
A deck lighting system according to the present invention is shown at 100.
The lighting system 100 includes a housing 101 with pair of lighting subsystems 102, 104 therein, and a protective glass cover 105. The lighting subsystem 102 projects light to a deck with a predetermined spatial distribution. The lighting subsystem 104 projects light to the deck with a spatial distribution that is different from the spatial distribution of the lighting subsystem 102. Together, the lighting subsystems 102, 104 project light to the deck in a manner that illuminates a portion of the deck, and in a wavelength band that is compatible with night vision goggles.
The lighting subsystem 102 includes a new optical projection structure, according to the principles of the present invention. The lighting subsystem 102 comprises (i) a source comprising first array of light emitting diodes (LEDs) 106, (ii) optical projection structure 107 associated with the first array 106 of LEDs, comprising a curved reflector segment 108 and collimator (or refractor) 110, and (iii) a filter 112 associated with the first array of LEDs. The first array of LEDs 106 is configured to generate light in a predetermined wavelength range (e.g. 575 nm to 450 nm or 525 nm to 425 nm) that is generally compatible with night vision goggles. The filter 112 is configured to substantially filter out light in a predetermined wavelength band (e.g. the light may be filtered to substantially attenuate light with a wavelength longer than 550 nm), that further reduces any light in the cyan waveband that is within the waveband of the night vision goggles. Thus, the filtered light is effectively “out of band” of the night vision goggles (i.e. it is completely out of a waveband that could interfere with the night vision goggles). It is also contemplated that if the light source can produce light in a wavelength range that is completely “out of band” of night vision goggles (or other wavelength range that completely eliminates light in a wavelength range that is undesirable), the filter can effectively pass all of the light from the array of LEDs. The optical projection device 107 projects the light to the center of the deck with a predetermined spatial distribution that is determined by the requirements of the user.
Preferably the curved light reflecting segment 108 reflects a portion of the light from the array of LEDs and the light refracting component 110 refracts (or reflects using total internal reflection and then refracts) a portion of the light from the array 106 of LEDs. The curved light reflecting segment 108 preferably comprises an extruded, concave parabolic reflector segment.
In the lighting subsystem 102 one preferred embodiment is to have curved reflector segment 108 or collimator 110 have constant cross section. An optic with constant cross section can be described with a cross section and a curve along which the cross section is swept. In the preferred embodiment, the curve the cross section is swept along is substantially defined by the curve connecting the centers of each LED in the array of light emitting diodes 106. It is also contemplated that the curve along which the cross section can be swept along can be a straight line segment, a smooth curve or a piecewise defined curve, as will be appreciated by those in the art. An additional preferred embodiment is for both the curved reflector segment 108 and collimator 110 to have constant cross sections.
As can be appreciated by reference to
Some of the useful features of the optical projection structure described above can be appreciated from a comparison of
Typically the reflector is a full parabolic mirror and the refractor is a lens.
Both have well defined focal points and the optics are typically designed so that the focal points are coincident. The source is placed proximate to the focal points and the light exiting the source is reflected or refracted such that the light is contained within a cone around the axis of symmetry when it leaves the system. Obviously, the reflector does not have to be parabolic and the refractor does not have to collimate the light well. These devices can be rotationally symmetrical to collimate the light in both directions, or they can be extrusions to collimate the light in one direction only.
The problem with the prior structure of
At least one mirror 116 is associated with the array 106 of LEDs of the lighting subsystem 102. Preferably, there are plural mirrors associated with the lighting subsystem 102, and they are located at the end of each row of LEDs. The mirror(s) create virtual images of the LEDs, thereby to increase the effective size of the array 106 of LEDs. In addition, with a ship deck lighting system, baffles or louvers 117 (
The other lighting subsystem 104 comprises a second array of light producing components 121, each of which preferably comprises an LED 120 and an optic 122 (e.g. a collimator or refractor) associated with the LED. Rather than individual optics 122, a common optic can be associated with the second array of LEDs 120. In addition, the filter 112 may also function as a filter for the second array of LEDs 120 (or an individual filter can be associated with each of the second arrays of LEDs 120). The optic(s) associated with the LEDs 120 could be separate parts or some or all of the optic(s) could be formed from one piece. If two or more optics are formed from the same piece, there will be a variation in the shape of the optics to match the spacing of the LEDs 120. While the preferred embodiment has the same spacing between the LEDs 120 and the variations in the shape of the optics, it is not necessary for the spacings to match. In some cases, a mismatch between the spacings can be used to direct light in different directions from different LEDs 120. This would allow for the LEDs 120 to be mounted on a flat surface while still allowing for the light from each LED 120 to be aimed in different directions. In another preferred embodiment, more than one LED 120 is associated with each individual optic. For example, two, three or more LEDs 120 could be associated with one optic that form part of an array of optics. The filter(s) for the second array of LEDs 120 may be a single filter for the second array of LEDs (i.e. part of the common filter 112), or an individual filter for each of the second array of LEDs 120. The filter(s) and optical devices 122 associated with the second array of LEDs 120 are configured to substantially filter out light in the predetermined wavelength band, e.g. if the LEDs 120 are configured to generate light in the same predetermined wavelength range as the LEDs 106 (e.g. 575 nm to 450 nm or 525 nm to 425 nm) that is generally compatible with night vision goggles, the filter, or filters, are configured to substantially filter out light in a predetermined wavelength band (e.g. the light may be filtered to substantially attenuate light with a wavelength longer than 550 nm), that further reduces any light in the cyan waveband that is within the waveband of the night vision goggles.
The filtered light from the second array of LEDs 120 is projected to the deck with a different spatial distribution than the projected light from the first lighting subsystem 102. Specifically, the filtered light from the second array of LEDs 120 is projected such that their spatial distribution effectively fills in gaps in the light projected from the first array of LEDs 106. Thus, if light from the first array 106 of LEDs is projected to the center of the deck, the light from the second array 120 of LEDs is projected to areas about the first array 106 of LEDs and off to the side of the light projected from the first array 106 of LEDs. This creates a spatial distribution from the second lighting subsystem 104 that differs from the spatial distribution created by the first lighting subsystem 102.
It should be further noted that the position and angle of each of the LEDs 106 of the first array or the LEDs 120 of the second array can be optimized, in accordance with the spatial distribution desired from each of the lighting subsystems. Moreover, the overall optical configuration of the lighting system 100 is preferably optimized by matching the éntendue of the sources to the specific areas on the deck to produce an intensity distribution over horizontal and vertical angles and in a tight vertical pattern, to enable the light from the first lighting subsystem 102 to be projected to the volume space in the tight vertical pattern. The angular subtense of the deck center is small relative to the lighting system. The tight vertical pattern is desirable to project sufficient optical power to illuminate the large area of the center of the deck.
The foregoing lighting system is designed for projecting light to the deck of a ship, but the principles of the lighting system can be used in other applications, especially those applications in which it is desirable to project light to a volume space while also filtering out light in an undesirable wavelength. For example, the principles of the present invention can be used in a street lighting system, in an area in which too much reflected light from the ground can effectively cause “light pollution” (e.g. an area that uses powerful optical telescopes that can be affected by such “light pollution”).
In addition, the principles of the present invention can be used in lighting systems that can switch between a broad band lighting system and a narrow band lighting system. For example, as illustrated by
Accordingly, the foregoing description provides a lighting system that is particularly useful as a deck lighting system for a ships deck, and which also has application in other types of lighting systems. Moreover, it will be apparent to those in the art that modifications of the lighting system and/or light projection structure described above can be made in accordance with the principles of the present invention. For example, while a parabolic, concave reflector segment 108 is disclosed above, it will be apparent to those in the art that other curved reflector segment configurations (e.g. curved concave spherical reflector segment, curved compound reflector segment that may have concave or other configurations) can also be used in an optical projection structure according to the present invention. In addition, while the cover (or window) 105 and filter 112 are illustrated as separate components, it is contemplated that the filter can be integrally formed with the window. Also, it is also possible to use a source with a broad spectral band and filter the light with an electronically controlled color filter. For example, one type of color filter that can be used is produced by ColorLink, Inc., Boulder, Colo., distributed under the mark ColorSelect, and uses polarization and technology called retarder stack technology that selectively rotate additive or subtractive color bands. Such retarder stack technology is described in U.S. Pat. Nos. 5,929,946; 5,953,083; 5,990,996; and/or 5,999,240, each of which is incorporated by reference herein. Another way would be to create a custom filter using filters, produced by ColorLink, Inc., distributed under the mark ColorSwitch, and which use liquid crystal switches configured to chromatically manipulate polarization, and which provide independent electronic control of the RGB transmission levels to provide additive and subtractive primary outputs. Such technology is described in U.S. Pat. Nos. 5,751,384 and/or 5,953,083, each of which is incorporated by reference herein. Another example of an electronically controlled color filter is to construct to incorporate a color filter array in a light valve. A particular example of this is to use a liquid crystal display with individually addressable regions. Different regions will have different color filters associated with them. By adjusting the transmission of the different regions independently, the overall spectral transmission of the filter can be adjusted. Also, an electromechanically controlled color filter could be moved into or out of a beam to adjust the color. In addition, while the preferred embodiment shows lighting subsystems 102, 104 within a common structure (i.e. within housing 101), it is not necessary to have lighting subsystem 104 contained in the same structure that contains lighting subsystem 102. Still further, mirrors 116, while described above in connection with lighting subsystem 102, can be associated with each of the lighting subsystems 102, 104.
With the foregoing disclosure in mind, it is believed that various adaptations of a lighting system and/or an optical projection structure, according to the principles of the present invention, will be apparent to those in the art.
This invention may have been at least partially supported by funding under US government SBIR Contract No. N65538-04-M-0098 awarded by the Department of the Navy, Naval Sea Logistics Center (NAVSEA). The government may have some rights in this invention.
