Information
-
Patent Grant
-
6286979
-
Patent Number
6,286,979
-
Date Filed
Thursday, February 24, 200024 years ago
-
Date Issued
Tuesday, September 11, 200122 years ago
-
Inventors
-
-
Examiners
- Sember; Thomas M.
- Alavi; Ali
Agents
-
CPC
-
US Classifications
Field of Search
US
- 362 297
- 362 298
- 362 301
- 362 302
- 362 303
- 362 304
- 362 305
- 362 346
-
International Classifications
-
Abstract
An optical integrating cavity supplies light or other radiant energy through a port to a deflector. The deflector coupled to the port may form a “fan” extending along one side or around all or part of the circumference of the cavity. Preferred embodiments use principles of constructive occlusion (diffuse reflectivity in a mask and cavity structure) together with the port and deflector structure. The cavity and mask serve as the optical integrating cavity. The constructive occlusion provides a tailored intensity distribution for radiant energy illuminating a first region; whereas the integrating cavity, port and deflector distribute another portion of the electromagnetic energy over a second field of intended illumination. The first and second areas illuminated may overlap slightly, or one may include the other, but preferably most of the two areas are separate. In some cases, the system configuration creates a dead zone between the two regions.
Description
FIELD OF THE INVENTION
The present invention relates to systems for illuminating a desired area with electromagnetic radiation, such as visible or infrared light, with a desired intensity distribution, for example using an integrating cavity, a port and a fan-shaped deflector structure. Preferably, the cavity takes the form a constructive occlusion type mask, cavity and shoulder providing a tailored intensity distribution of radiant energy over one region, while the port and deflector provide illumination of another region.
BACKGROUND
Radiant or electromagnetic energy emitters and distributors find a wide range of applications in modern society. Visible illumination systems, for example, illuminate areas and surfaces to enable use by personnel even though natural ambient lighting might be insufficient. Infrared illumination is a critical component of many night-vision technologies.
Different applications of radiant energy illumination systems require different performance characteristics. For example, a visible illumination application might require that the lighting system provides a desired minimum intensity over a flat surface of specified dimensions about an axis of the lighting system, at a known distance from the system along its axis. Simple radiation sources, such as light emitting diodes (LEDs) or light bulbs with reflectors and/or lenses typically provide a high intensity radiation in regions close to the axis, but the intensity drops off quickly at angles approaching the horizon. On an illuminated surface, the intensity is not uniform, as often desired.
To provide a desired illumination at edges of a design footprint, the source often will emit substantially higher amounts of radiation than necessary along the axis. Although such an approach may meet minimum requirements, it requires an excessive amount of power.
Prior attempts to provide desired intensity distributions have involved complex arrangements of sources, lenses and reflectors. These complex arrangements tend to be relatively expensive and sensitive to problems of misalignment, which limits ruggedness and durability.
As an example of a difficult lighting application, consider illumination of the vehicle filling area, under a canopy, in a modern self-serve type gas station or the like. Light fixtures are attached to the underside of the canopy. Such fixtures must distribute light downward toward the ground. The illumination system must also provide some illumination at an angle to illuminate vertical surfaces of the pumps. To achieve desired lighting, the requirements for such an application actually specify desired downward intensity and angular coverage and require some amount of up-lighting at an angle onto the underside of the canopy. A problem arises, however, where illumination systems meeting such requirements also distribute a substantial portion of the light outward at angles approaching the horizon. The light emitted in this later direction actually “trespasses” on adjacent properties, and in many instances, is disturbing to persons living on or using the adjacent properties.
U.S. Pat. No. 5,733,028 issued Mar. 31, 1998 to Ramer et al. discloses a number of embodiments of illumination systems that utilize constructive occlusion. With this technology, a mask occludes an active optical surface, typically a Lambertian surface formed by the aperture of a diffusely reflective cavity. In most embodiments, a reflective shoulder surrounds all or at least a portion of the aperture. The mask, cavity and shoulder distribute radiant energy from within the cavity out over an area, with a tailored intensity distribution. The disclosure there emphasizes uniformity of the intensity distribution, for example with respect to angles extending over a hemispherical radiation pattern. Adjustment of the parameters of the constructive occlusion system enables the system designer to tailor the system performance to a wide range of applications.
However, a need still exists for radiant energy or electromagnetic emission and distribution systems, which can satisfy certain specialized requirements as to a desired intensity distribution. Such systems must be relatively simple in structure, to minimize cost and maximize durability. Also, such systems should be able to achieve a desired intensity distribution including at least some area beyond the horizon of the aperture, and in some instances exhibiting a dead zone at or near the horizon. In the gas station example, such a dead zone at or near the horizon would help to minimize light trespass on adjacent properties.
DISCLOSURE OF THE INVENTION
The invention addresses the above stated needs and overcomes the stated problems by providing a port and deflector structure on an optical-integrating cavity, preferably the cavity in a mask and cavity type constructive occlusion illumination system.
One aspect of the invention relates to a lighting system, comprising a diffusely reflective optical-integrating cavity and a source coupled to emit light into the cavity. An elongated port extends along a portion of a perimeter of the cavity. This port provides passage for light from within the cavity. The system includes two reflectors mounted along opposite edges of the port. Each reflector has a reflective surface extending at an angle from one elongated edge of the port toward a region to be illuminated. These reflective surfaces form a deflector, coupled to the port. In a circular system embodiment, for example, the deflector would fan around all or a part of the periphery of the circular cavity. One or more deflectors may fan or extend along the side(s) of a rectangular system. The deflector expands outward along its length as the surfaces extend toward a region to be illuminated. The deflector directs the light from within the cavity over the region to be illuminated.
The deflector surfaces may be formed on a variety of structures. For example, the reflectors may be formed on facing surfaces of two angled plates or on a surface of a solid base and an opposing surface of a plate. Alternatively, the deflector may utilize total internal reflection, in which case, the surfaces correspond to the boundaries between a transparent solid and the surrounding environment.
The preferred embodiments combine the port and deflector structure with the elements of a constructive occlusion illumination system. The constructive occlusion provides illumination for one region, and the port and deflector illuminate another region.
Another inventive aspect therefore relates to a system for projecting electromagnetic radiation with predetermined intensity over two distinct regions. The system includes a base, which has a defined area substantially facing a first region to be illuminated. This area of the base exhibits a reflective characteristic with respect to the electromagnetic radiation. Preferably, a shoulder is adjacent to and extends along a portion of the defined area of the base, although the shoulder may be omitted. If included, the surface of the shoulder, which faces toward at least a portion of the first region, has a reflective surface. The system further includes a mask between the base and the first region, at a predetermined distance from the defined area of the base. On the mask, an area substantially facing the defined area of the base also is reflective. A source emits electromagnetic radiation for reflection between the defined areas of the base and mask, such that the base, mask and shoulder provide a tailored intensity distribution of electromagnetic radiation over the first region to be illuminated. The system also includes a port and a deflector. The port extends through the base or the mask, from the defined area thereof toward a second region to be illuminated. The deflector has a reflective inner surface extending and expanding from a narrow end coupled to the port toward the second region. The regions may overlap, or one region may include the other. In certain preferred embodiments, the second region includes at least a substantial area that is outside the first region. In several of these embodiments, a dead zone that the system does not illuminate separates the two regions.
In the preferred embodiments, one of the defined areas comprises the aperture of a diffusely reflective cavity. The cavity therefore may be in the base or the mask, although often it is formed in the base.
The mask and cavity system may take a variety of different shapes. In many cases, these elements are circularly symmetrical about a common axis. For example, the cavity may take the form of a segment of a sphere, often approaching a hemisphere. The aperture is a flat, circular opening. The mask may be a flat disk, or the mask may contain a reflector surrounding the light source. In such cases, the preferred deflector forms a fan extending around at least a portion of the base.
In an embodiment of the system that is substantially symmetrical about the axis, the port and fan may actually encircle the system. For example, the port may take the form of an annular ring opening outward from a hemispherical cavity. In a rectangular embodiment, the cavity takes the form of a segment of a cylinder. In this example, there may actually be two ports extending in parallel along opposite sides of the cavity and two deflectors. Each deflector forms a straight fan along one side of the system. The invention also encompasses embodiments with additional ports and deflectors coupled to the base and/or the mask at various peripheral or elevational locations.
The inventive illumination system can provide desired intensity illumination over two or more different regions, which may be totally separated. In the gas station application, for example, one region illuminated by constructive occlusion would be under the canopy. The other region may actually be above the system on the underside of the canopy, to provide indirect illumination of vertical services within the service area. A dead zone between the two regions, created by the shoulder and a fan-shaped deflector structure, prevents radiation of energy out into areas around the horizon of the system, and thereby minimizes light trespass on properties adjacent to the service station.
The inventive systems provide desired intensity illumination over precisely defined systems, with little or no illumination in undesired areas. The use of highly reflective materials within the system together with the system structure serves to distribute virtually all of the radiant energy into the desired regions. As a result, the inventive systems also are highly efficient.
Additional objects, advantages and novel features of the invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
BRIEF DESCRIPTION OF DRAWINGS
The drawing figures depict the present invention by way of example, not by way of limitations. In the figures, like reference numerals refer to the same or similar elements.
FIG. 1
is a cross-sectional view of a mask, cavity and shoulder type illumination system utilizing constructive occlusion, useful in explaining certain concepts of the present invention.
FIG. 2
is a cross-sectional view of a simple embodiment of an illumination system utilizing constructive occlusion in combination with a port and deflector structure, in accord with the principles of the present invention.
FIG. 2A
is a top plan view of the illumination system of
FIG. 2
,
FIG. 2B
is a top plan view of a system similar to that of
FIG. 2
with a modified fan design for the deflector structure.
FIG. 3
is a cross-sectional view of another simple embodiment of an illumination system utilizing constructive occlusion in combination with a port and deflector structure, in accord with the principles of the present invention.
FIG. 4
is a plan view of a first preferred embodiment of a lighting system utilizing a mask, cavity and shoulder in combination with a pair of ports and deflector structures.
FIG. 5A
is a cross-sectional view of the embodiment of
FIG. 4
taken along line
5
—
5
.
FIG. 5B
is a cross-sectional view of an alternative embodiment of the system of
FIG. 4
, wherein the deflector has curved walls.
FIG. 5C
is a cross-sectional view of system similar to that of
FIGS. 4 and 5A
but with the addition of a totally internally reflective deflector coupled to a port through the mask.
FIG. 6
is a computer line drawing of a second preferred embodiment of a lighting system utilizing the principles of the invention, for example, for illumination under a canopy in a service station or the like.
FIG. 7
is a cross-sectional view of the embodiment of FIG.
6
.
FIG. 8
is a side view of the embodiment of FIG.
6
.
FIG. 9
is a bottom plan view of the embodiment of FIG.
6
.
FIG. 10
is a polar plot, and
FIG. 11
is a graph, of intensity versus angle from the down axis, useful in explaining the performance of the system shown in
FIGS. 6
to
9
.
FIG. 12
is a front-side view of a wall-mount system utilizing the inventive concepts.
FIG. 13
is a cross-sectional view of the embodiment of
FIG. 12
taken along line
13
—
13
.
FIG. 14
is a bottom plan view of the system of FIGS.
12
and
13
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention utilizes an integrating cavity with a port and deflector along a portion of the perimeter of the cavity. Typically, the deflector is in the form of a “fan” extending along one side or around all or part of the circumference of the cavity. The preferred embodiments use principles of constructive occlusion (diffuse reflectivity in a mask and cavity structure) together with the port and deflector structure. To the port and deflector structure, the cavity and mask serve as the optical integrating cavity.
The constructive occlusion provides a tailored intensity distribution for radiant energy illuminating a first region. A reflective structure, typically expanding outward as it extends out from the port, serves as the deflector to distribute another portion of the electromagnetic energy over a second field of intended illumination. The first and second areas illuminated by such a system may overlap slightly, but preferably most of the two areas are separate. In several preferred embodiments a dead zone, which receives little or no radiant energy from the system, actually separates the two regions. The invention contemplates configurations of the system components to offer a variety of different intensity distributions in one or both of the fields of intended illumination. The invention also encompasses embodiments having one or more additional ports and deflectors to illuminate additional regions.
The combination of illumination by constructive occlusion in one region with port and deflector illumination of a separate region enables the designer to precisely tailor the illumination system to the needs of certain specific applications with little or no energy lost to irradiation of areas outside the intended fields of illumination. One particular example enables the designers to create a dead zone, so as to prevent light-trespass. In such a system, the energy that another type of system would direct into undesirable areas actually is redirected within the inventive system to illuminate the desired areas. Consequently, the inventive system provides particularly high efficiencies and enables the use of lower power and/or smaller or fewer sources of radiant energy to achieve the desired levels of illumination. The illuminating systems are relatively simple in design, making the inventive devices relatively cheap to manufacture as well as more durable than prior systems designed to meet similar application requirements.
Those skilled in the art will recognize that the principles of the present invention are applicable to distribution of various forms or wavelengths of radiant energy or electromagnetic radiation. The preferred embodiments relate to illumination with visible light, and the following discussion will concentrate on discussion of lighting systems, although clearly the invention encompasses radiation of other forms of electromagnetic energy.
FIG. 1
depicts a first, simple embodiment of a light distributor apparatus or system
11
, for projecting light with a tailored intensity distribution using the principles of constructive occlusion. In the illustration, the system
11
is oriented to provide downward illumination. Such a system might be mounted in or suspended from a ceiling or canopy or the like. Those skilled in the art will recognize that the designer may choose to orient the system
11
in different directions, to adapt the system to other lighting applications.
The light distributor
11
includes a base
13
, having or forming a cavity
15
, and an adjacent ring-shaped shoulder
17
. A disk-shaped mask
19
is disposed between the cavity aperture
23
and the field to be illuminated. In this symmetrical embodiment, the aperture
23
is circular, and the shoulder
17
completely surrounds the aperture
23
.
In many embodiments, the cavity
15
comprises a substantial segment of a sphere. For example, the cavity may be substantially hemispherical as shown. However, the cavity's shape is not of critical importance. A variety of other shapes may be used. For example, half-cylindrical cavities having a square or rectangular aperture or even having a nearly linear aperture with a narrow rectangular opening are contemplated for certain specific applications requiring a more rectangular illumination footprint in the region illuminated by the constructive occlusion technique. Practically any cavity shape is effective, so long as it has a diffuse reflective inner surface. A hemisphere is preferred for the ease in modeling its azimuthal symmetry and for its ease in construction. In the illustrated embodiment, the base and the shoulder are circular, although other shapes may be used.
The mask
19
is positioned between the base
13
and the target area, region or surface to be illuminated. As such, the mask
19
is outside of the cavity
15
. For example, in the orientation shown, the mask
19
is below the aperture
23
of the cavity
15
in the base
13
.
A source
21
emits electromagnetic radiation, for example as visible light, into the volume between the cavity surface and the facing surface of the mask. The system may include a variety of different types of sources, including light bulbs, one or more LEDs, and one or more optical fibers coupled to remote light generation components. In the example shown, the light source
21
is an idealized spherical source emitting radiation in virtually all directions.
In this first embodiment, the base
13
, the shoulder
17
and the mask
19
preferably are formed of a suitable diffusely reflective material such as Spectralon®, which is a highly reflective polymeric material manufactured and sold by Labsphere, Inc., of North Sutton, N.H. This material is easily machined and very durable, and it provides a highly efficient Lambertian surface having a reflectance of more than 99%, for visible and near-infrared wavelengths. A Lambertian surface emits light with substantially uniform intensity in all directions. W. L. Gore & Associates offers a material with similar performance characteristics under the trademark Whitestar.
Alternatively, the base
13
and the mask
19
could be constructed of a suitable base material of, for example, aluminum or plastic, with a coating of a diffuse reflective material such as barium sulfate, Spectralon or Whitestar on the appropriate surfaces. Other suitable materials, though less effective than the diffuse reflective materials identified above, include quasi-diffuse reflective materials, such as gloss white paint. The use of such materials provides improved performance over prior light distributors.
The light source
21
emits light into the base cavity
15
. The light source
21
also directs some light toward the mask
19
, and the light source
21
may direct some light toward the shoulder
17
. The light source
21
may emit some light directly through the gap between the aperture
23
and the mask
19
. Light rays impacting on the diffusely reflective surfaces, particularly those impacting on the inner surface of the cavity
15
and the facing surface of the mask
19
, reflect and diffuse one or more times within the confines of the system and eventually emerge through the gap between the perimeter of the aperture and the edge of the mask. The shoulder diffuses and reflects some of this light toward the field of intended illumination.
For purposes of constructive occlusion, the base
13
may be considered to have an active optical area, preferably exhibiting a substantially Lambertian energy distribution. Where the cavity is formed in the base, for example, the planar aperture
23
formed by the rim or perimeter of the cavity
15
forms the active surface with substantially Lambertian distribution of energy emerging through the aperture. As shown in a later embodiment, the cavity may be formed in the facing surface of the mask. In such a system, the surface of the base may be a diffusely reflective surface, therefore the active area on the base would essentially be the mirror image of the cavity aperture on the base surface, that is to say the area reflecting energy emerging from the aperture of the cavity in the mask.
In accord with the invention, the mask
19
constructively occludes a portion of the optically active area of the base with respect to the field of intended illumination. In the example of
FIG. 1
, the optically active area is the aperture
23
of the cavity
15
; therefore the mask
19
occludes a substantial portion of the aperture
23
, including the portion of the aperture on and about the axis of the mask and cavity system.
The relative dimensions of the mask
19
and aperture
23
, for example the relative diameters or radii in the circular embodiment as well as the distance of the mask
19
away from the aperture
23
, control the constructive occlusion performance characteristics of the light distributor system
11
. Certain combinations of these parameters produce a relatively uniform intensity with respect to angles of emission, over a wide portion of the field of view about the system axis (vertically downward in FIG.
1
), covered principally by the constructive occlusion. Other combinations of size and height result in a system performance that is uniform with respect to a wide planar surface perpendicular to the system axis at a fixed distance from the aperture.
The shoulder
17
also reflects at least some light downward. The angle of the shoulder and the reflectivity of the surface thereof facing toward the region to be illuminated by constructive occlusion also contribute to the intensity distribution over that region. In the illustrated example, the diffusely reflective shoulder
17
is angled somewhat downward from the plane of the aperture
23
toward the first region to be illuminated.
FIG. 2
is a cross-sectional view of a first embodiment of the invention, combining the constructive occlusion principles of the system of
FIG. 1
with a port and a fan-like light distributor or deflector structure. The system
211
distributes light rays such as L
1
over a first region or field F
1
of intended illumination by constructive occlusion. The cavity and mask may be considered as a rough approximation of a spherical integrating cavity. This integrating cavity couples light to the port and deflector, which directs light rays such as L
2
toward a second field or region F
2
intended for illumination.
In the illustration, the system
211
includes a base
213
having or forming a cavity
215
. If fully extended to the aperture
23
, the cavity
215
would have essentially the same shape as the cavity
15
in system
11
(FIG.
1
). Again, the ring-shaped shoulder
17
surrounds the aperture
23
. For purposes of this discussion, the aperture
23
forms the active optical area with respect to the base
213
. A disk-shaped mask
19
is disposed between the cavity aperture
23
and the first field F
1
to be illuminated (downward in the illustrative orientation). As in the system
11
, the inner surface of the cavity
215
and the facing surface of the mask
19
are diffusely reflective. The surface of the shoulder
17
facing toward a portion of the first region F
1
is reflective, although it may be specular or diffusely reflective. These elements illuminate the first region F
1
by constructive occlusion essentially as described above. The drawing shows limited examples L
1
of the light rays produced by constructive occlusion to illuminate the first area F
1
.
In the system
211
of
FIG. 2
, however, the base
213
has one or more elongated ports
25
. In this case, the port(s)
25
represent one or more openings from the cavity
215
outward and somewhat away from the first intended field of illumination. A deflector
27
, preferably formed as a fan-shaped structure located along the port(s), directs light emerging from the cavity through the port(s)
25
toward the second region intended for illumination by the system
211
.
In the example illustrated in
FIG. 2
, assume that the cavity
215
is substantially hemispherical. The port
25
preferably takes the form of an annular opening in the shape of a ring around the cavity. In this example, the annular opening
25
is spaced a distance from the aperture
23
, although later examples include embodiments wherein the port is substantially adjacent the aperture.
FIG. 2A
is a top plan view of the system of
FIG. 2
, showing the deflector fanning out around the system, so as to completely encircle the port formed around the perimeter of the base
213
.
The port
25
allows some light processed within the cavity
215
to emerge outward in a different direction, separate and apart from the light processed and emitted downward by the constructive occlusion technique. Light passing through this port
25
enters a spreading or expanding-height deflector
27
. Viewed in cross-section, on each side of the base
213
, the exemplary deflector structure
27
has a cross-section similar to that of a cone with a straight angled wall. The narrow end of the inner surface of the deflector
27
is optically coupled to the port
25
. The deflector
27
expands (in height in the illustrated orientation) as it extends from the port
25
toward the second area F
2
of intended illumination.
In this embodiment the port
25
and the associated fan-shaped deflector
27
completely encircle the base
213
and cavity
215
(see FIG.
2
A).
FIG. 2B
shows a modified version of the deflector
27
′. In that implementation, the deflector forms a fan only partially extending around the perimeter of the base
213
. Although not visible in this view, the port typically would extend only part-way around the cavity.
In the illustrated example, the deflector essentially comprises two angled planar surfaces. The entire area of each of these surfaces is reflective. At least a portion of each reflective surface of the deflector
27
is specular. A specular, reflective material reflects light in such a manner that the angle of reflection of the redirected light with respect to the reflective surface has the same magnitude as the angle of incidence of the incoming light relative to that surface. However, the term “specular” covers a range of materials and reflectivities. A highly specular material has a mirror-like finish, for example formed by silver and glass coatings or formed of highly polished aluminum. A quasi-specular material will not reflect as efficiently as a highly specular material and may cause some diffusion of the light. However, most of the reflected light will satisfy the principle that angle of reflection equals angle of incidence. As an example, a quasi-specular surface may be formed of lightly polished aluminum.
Preferably, a substantial portion of each inner surface of the deflector
27
has a specular reflectivity. The entire surface may be uniformly specular (e.g., highly specular). Alternatively, one or more sections of the inner walls of the deflector may have a diffuse reflectivity or a different degree of specular reflectivity (e.g., quasi specular). The port
25
and the deflector
27
are dimensioned relative to a desired field of illumination such that the inner surface of the deflector
27
deflects light that would otherwise pass out of the desired second field of intended illumination within that desired field F
2
. Around its circumference, the fan-shaped deflector structure will direct or distribute light from the port
25
, represented on the left side by the light rays L
2
, toward the second area F
2
that the system
211
is designed to illuminate. The fan-shaped deflector
27
may provide a substantially uniform light intensity distribution over the second field of intended illumination F
2
.
In the illustrated example, the second area F
2
illuminated through the port and distributor extends out toward and somewhat above the horizon of the system
211
. Near the shoulder
17
, the two fields of illumination F
1
and F
2
may not overlap. However, at substantial distances from the system, the two fields will overlap somewhat. It should be apparent, however, that despite the overlap the two fields of view of the system
211
actually illuminate two substantially different areas. The central portion of the first field of view is not illuminated by any light from the port
25
or the deflector
27
. Instead that portion of the first field F
1
is illuminated only by the constructive occlusion processing. Conversely, the portion of the second field F
2
that extends substantially above the system horizon receives little or no light from the constructive occlusion illumination of the area F
1
.
FIG. 3
illustrates another exemplary lighting system
311
embodying the principles of the present invention. The system
311
comprises a base
313
, a mask
319
, a light source
321
and a conical deflector
327
. The system is circularly symmetrical about a vertical axis, although it could be rectangular or have other shapes. The base includes a flat central region
323
that is reflective and forms or contains the active optical area on the base facing toward the first region or area to be illuminated by the system
311
.
The mask
319
is positioned between the base
313
and the region to be illuminated by constructive occlusion. For example, in the orientation shown, the mask
319
is below the active optical area
323
of the base
313
.
In this embodiment, the mask
319
contains the diffusely reflective cavity
315
. The aperture
324
of the cavity
315
and any diffusely reflective surface that may surround that aperture form the active optical area on the mask
319
. Such an active surface faces toward the active surface
323
on the base
313
. The surface
323
is reflective, preferably with a diffuse characteristic. The surface
323
of the base
313
essentially acts to produce a diffused mirror image of the mask
319
with its cavity
315
as projected onto the base surface
323
. The surface area
323
reflects energy emerging from the aperture
324
of the cavity
315
in the mask
319
. The mask
319
in turn constructively occludes light diffused from the active base surface
323
with respect to the first region illuminated by the system
311
.
A source
321
emits electromagnetic radiation, for example as visible light, into the volume between the cavity surface and the facing surface
323
of the base. The system may include a variety of different types of sources, including light bulbs, one or more LEDs, and one or more optical fibers coupled to remote light generation components. In the example shown, the light source
321
is an idealized spherical source emitting radiation in virtually all directions.
The base
313
in the system
311
also includes a ring-shaped shoulder
317
. The lower surface of the shoulder
317
is reflective, as in the earlier embodiments. Although the angle of the shoulder surface may be different for different applications, the angle shown is essentially the same as in the previous embodiments.
The light source
321
emits light into the mask cavity
315
. The light source
321
directs some light toward the surface
323
on the base. The light source
321
may direct some light toward the shoulder
317
. Although not shown, the light source
321
may emit some additional light directly through the gap between the mask
319
and the base
313
. Light rays impacting on the diffusely reflective surfaces, particularly those on the inner surface of the cavity
315
and the facing surface
323
of the base
313
, reflect and diffuse one or more times within the confines of the system and emerge through the gap between the perimeter of the active area
323
of the base and the edge of the mask
319
. The light emitted through the gap and/or reflected from the surface of the shoulder
317
irradiates the first region with a desired intensity distribution, essentially as in the earlier embodiments.
The system
311
also includes a port
325
extending through the base
313
, from the optically active area
323
toward a second region to be illuminated. In the illustrated example, the port
325
takes the form of a circular opening along the system axis. However, the port
325
may have other shapes, locations or orientations, in order to direct light from the source
321
and the volume between the base
313
and the mask
319
toward another desired area of illumination. For some applications, there may be two or more such ports
325
through the base
313
.
The system
311
includes a deflector
327
coupled to the port
325
. The deflector
327
has the shape of a truncated cone, in this embodiment, with a circular lateral cross section. The cone has two circular openings. Although not shown, the large opening may be covered with a transparent plate or lens, to prevent entry of dirt or debris through the cone into the system. The cone tapers from the large end opening to the narrow end opening, which is coupled to the port
325
. The narrow end of the deflector cone receives light from the source
321
and from diffuse reflections between the base
313
and the mask
319
.
The entire area of inner surface of the cone
327
is reflective. At least a portion of the reflective surface is specular. In the system of
FIG. 3
, for example, the specular surface within the conical deflector
327
may be quasi-specular or highly specular. Some portions, such as along the edge at the large opening, may exhibit other types of reflectivity. For purposes of further discussion of
FIG. 3
, it is assumed that the entire inner surface of the conical deflector
327
has a uniform specular reflectivity. The angle of the wall(s) of the conical deflector
327
substantially corresponds to the angle of the desired field of view of the illumination intended for the second region. Because of the reflectivity of the wall of the cone
327
, most if not all of the light reflected by the surface would at least achieve an angle that keeps the light within the field of view.
In the illustrated example, the system
311
provides a tailored intensity illumination of a relatively large region below the base and mask. Depending of the system parameters, the intensity distribution may be substantially uniform over a range of angles, or the system may provide an intensity distribution having a substantial planar uniformity over a wide footprint. The elements may readily be adapted to provide other distributions over the first region of illumination, to meet a wide range of lighting system design criteria.
The conical deflector
327
and the port
325
enable the system to concurrently illuminate a separate, second region, over a relatively narrow range of angles. The size of the port
325
substantially determines the percentage of light directed toward the second region. The angle of the wall of the conical deflector
327
substantially determines the range of angles within the field of view and thus the size of the illumination footprint in the second region.
The conical deflector
327
, with a specular inner surface provides a substantially uniform illumination within the limited field of view; however, other deflector shapes and reflectivities may be used to provide different intensity distributions and/or different illumination footprints in the second illuminated region. For example, if the desired footprint is not along the axis of the conical deflector
327
, the deflector may further comprise an angled reflective surface or mirror
327
. This additional deflector component directs the light emerging from the cone off in another direction, for example, to one side in the version shown.
FIG. 4
is a plan view and
FIG. 5A
is a cross-sectional view of an embodiment of the principles of the invention in a first practical lighting system design application. This particular system
411
is optimized for providing an up-light illumination, albeit with a relatively high intensity in areas nearing the horizon to the right and left sides of the system. As in the earlier embodiments, the system
411
comprises a base
413
. In this case, the base
413
has a diffusely reflective cavity
415
. The cavity takes the form of a portion or segment of a cylinder, such as a half-cylinder with closed ends. Such a cavity presents a rectangular aperture toward the first area to be illuminated.
The illustrated version exhibits a relatively wide rectangular aperture. For some applications it may be desirable to lengthen the system and narrow the cavity and aperture such that the long narrow aperture approximates a nearly linear opening or slit.
In this embodiment, the ports
425
,
426
are formed along respective boundaries between the sides of the cavity
415
and the shoulders
417
,
418
. Consequently, the inner edges of the shoulders
417
,
418
actually define the aperture
423
for constructive occlusion purposes with respect to the first region intended for illumination by the system. This aperture
423
is said to be the aperture of the base-cavity
415
and define the active optical area of the base
413
essentially as if the sides of the cavity extended to the edges of the shoulders
417
,
418
(without side ports
425
,
426
).
A mask
419
constructively occludes light diffused within the cavity from a source
421
and passing through a cavity aperture
423
. The mask
419
has a diffusely reflective surface facing toward the aperture
423
. In one actual implementation of this embodiment, the ratio of the dimensions, of the mask relative to the aperture, is 0.98.
This embodiment may be circular, or as shown, this embodiment may be rectangular. A rectangular version may approach a square, or the long dimension may be sufficiently longer than the narrow dimension that the aperture and mask become virtually linear in appearance.
In the illustrated implementation, the ends of the system above the base (top and bottom in the orientation of
FIG. 4
or at the back when shown in the cross-section of
FIG. 5A
) are open. There could be a wall across one or both ends, or the shoulder and fan structures could extend around one or both ends, depending on the desired illumination around the ends of the system.
The first field to be illuminated is vertically above the system
411
in the orientation illustrated in FIG.
5
A and is substantially centered about the vertical axis (180°). In this system
411
, there are actually two shoulders
417
,
418
. The shoulders extend along the longer sides of the rectangular cavity near the sides of the aperture
423
. Essentially, each shoulder is constructed of a flat plate mounted at the desired angle with respect to the plane of the aperture
423
. The upper surface of each shoulder, facing a portion of the first intended field of illumination, has a light reflective characteristic. In the preferred form of this embodiment, the surface of each of the two shoulders
417
,
418
is specular, although a diffuse reflectivity could be used on the shoulders.
The up-light system of
FIGS. 4 and 5A
includes two ports
425
,
426
providing rectangular openings into the opposing sides of the partially cylindrical cavity
415
. The system includes a deflector structure
427
coupled to the port
425
and a deflector structure
428
coupled to the port
426
. The port
425
and the deflector structure
427
direct light from the cavity
415
toward the horizon on one side of the system (to the right in the drawings). Similarly, the port
426
and the deflector structure
428
direct light from the cavity
415
toward the horizon on the other side of the system (to the left in the drawings).
In the system of
FIGS. 4 and 5A
, the plates forming the shoulders
417
,
418
together with upper surfaces of the base
413
form the two fan-shaped deflectors
427
,
428
, one of which is coupled to each of the elongated ports. The interior surfaces of the two fan-shaped deflector structures
427
,
428
are substantially specular, as in the earlier embodiments. In the deflector
427
, one specular surface is formed on the underside of the plate forming the shoulder
417
, and the other specular surface of that deflector is formed on the top surface of the base
413
. Similarly, in the deflector
428
, one specular surface is formed on the top surface of the base
413
, and the other specular surface of the deflector is formed on the underside of the plate forming the shoulder
418
.
The light source
421
is a fluorescent lamp, that is to say in the form of an elongated tube. In this embodiment, the light source preferably is linear and extends along a substantial portion of the cavity, but other light sources could be used. For example, a remote lamp could transmit light to specific points along the cavity wall through a series of optical fibers coupled to openings through the base into the cavity or through the mask.
The source
421
could be positioned virtually anywhere so that its light passes into the space between the mask and cavity. However, it is preferred that the source
421
be located so that the source
421
transmits some portion of its light energy directly through the ports
425
,
426
into the associated deflector structures
427
,
428
. The light source
421
may transmit some light directly through the ports and deflector structures into the respective fields of view. With the ports and deflectors located substantially as shown, the fluorescent lamp
421
should reside near the surface of the mask
421
, to maximize the output into the second and third regions illuminated by the system.
With respect to the mask
419
, the cavity aperture
423
appears to be a planar Lambertian diffusion surface or source. With respect to each port and fan-shaped deflector structure, the combination of the mask
419
and the cavity
415
forms an integrating cavity for efficiently coupling light from the source
421
through the respective port
425
or
426
.
The port and fan structures provide relatively high-intensity illumination out toward the horizon of the system
411
. The constructive occlusion provides a lower intensity illumination directly above the system. The constructive occlusion illumination extends outwards towards the horizon and to some extent overlaps the areas illuminated through the deflectors
427
and
428
.
In the illustrated orientation, the system
411
does not provide any illumination downward (0°). The system begins to provide illumination only at angles approaching the horizon (90°). However, in the region just above the horizon, the deflector structure
427
or
428
provides a relatively high-intensity illumination, for example from approximately 95° to 125°. The illumination intensity tapers off to a more uniform level, provided by the constructive occlusion for angles ranging from about 145° to 180°(vertical).
The system
411
may be used as a “trougher” light, with a fluorescent lamp source, hanging down from but aimed up toward a ceiling. Actual illumination of an area by such a light relies on light bouncing down off of the ceiling. Because of the performance of the inventive design, the system
411
can provide superior lighting when hung as close as five inches below the ceiling. Prior trougher lights must be hung fifteen or more inches from the ceiling to obtain similar desirable results.
FIG. 5B
illustrates an alternate cross-section of the system. The system
411
B uses curved deflectors
427
B,
428
B. The cavity
415
, the mask
419
, the aperture
423
, the lamp
421
, and the ports
425
,
426
are the same as the like-numbered elements in the system
411
of
FIGS. 4 and 5A
. The base
413
B is essentially similar to the base
413
, except that the upper surfaces on the sides of the cavity
415
curve upward as they extend out away from the ports
425
,
426
. These surfaces are reflective, preferably with a specular reflectivity, so as to function as part of the respective deflectors
427
B and
428
B.
In this system
411
B, there are two shoulders
417
B and
418
B along the longer sides of the cavity
415
near the sides of the rectangular aperture
423
. Essentially, each shoulder is constructed of an upwardly curved plate mounted at the desired angle with respect to the plane of the aperture
423
. The upper surface of each shoulder, facing a portion of the first intended field of illumination, has a light reflective characteristic. In the preferred form of this embodiment, the upper surface of each of the two shoulders
417
B,
418
B is specular, although a diffuse reflectivity could be used on the shoulders. The lower surfaces of the curved plates
417
B and
418
B are substantially specular, as in the earlier embodiments.
The curvature of the plates forming the shoulders
417
,
418
provides an added degree of structural strength and rigidity. The resulting curved deflectors
427
B and
428
B, however, provide substantially the same distribution of light over the respective fields of illumination as do the deflectors
427
and
428
in the preceding embodiment. The shoulders also function essentially as in the earlier embodiment of FIG.
5
A.
FIG. 5C
illustrates an alternative embodiment
411
C of the up-light. The cavity
415
, the aperture
423
, the lamp
421
, the shoulders
417
,
418
, the ports
425
,
426
, and the deflectors
427
,
428
are the same as the like-numbered elements in the system
411
of
FIGS. 4 and 5A
. The system
411
C, however, includes an additional deflector
429
coupled to a third port
431
. Although the port
431
could extend through the base and provide an optical coupling to the cavity
415
, in this example, the port
431
extends through the mask
419
C. The deflector
429
, in turn, extends outward from a defined area of the mask
419
C (in this case the reflective surface facing the aperture) toward another field intended for illumination.
The embodiment of
FIG. 5C
illustrates a number of additional inventive concepts. The port
431
and the deflector
429
provide a direct illumination of a portion of the light from the lamp
421
toward a desired area of illumination. The system
411
C provides distinct illumination of four different areas or fields. The first area is illuminated by the constructive occlusion processing. The second and third areas are illuminated via the ports
425
,
426
and the deflectors
427
,
428
; whereas light from the port
431
and the deflector
429
illuminates a fourth area. The area illuminated via the port
431
and the deflector
429
, however, actually is contained entirely within the first area illuminated by the constructive occlusion processing.
The deflector
429
could take a number of different forms. In a circular system, the deflector
429
could take the form of a truncated, straight-sided cone having a substantially specular reflectivity on its inner surface, similar to the deflector
327
shown in FIG.
3
. In such a case, the port
431
would be circular.
In the embodiment illustrated in
FIG. 5C
, however, the port
431
would be elongated, either to form a rectangle or to form an elongated oval (straight-sided but with rounded ends). Assume for the moment that the port
431
is an elongated rectangle. In such a case, the deflector could comprise two plates having opposing surfaces with a specular reflectivity.
As shown, the embodiment of
FIG. 5C
uses a solid deflector
429
and relies on total internal reflectivity. The deflector
429
consists essentially of a solid piece of transparent material, such as Acrylic or glass, constructed in such a manner that the light passing therethrough is totally internally reflected. Internally, such a solid is relatively transparent, but each boundary interface between the material and the surrounding environment functions as a substantially specular reflective surface. Hence, it should be understood by those skilled in the art that utilizing a solid piece of transparent material for the deflector
429
constructed so that there is total internal reflection results in the surfaces
433
and
435
of such material being equivalent to the reflective surfaces of the other deflectors, such as those of the deflectors
427
and
428
.
FIG. 6
is a computer line drawing,
FIG. 7
is a partial cross-section view,
FIG. 8
is a side view, and
FIG. 9
is a bottom plan view, of another preferred embodiment of the invention. This embodiment is particularly useful in certain under-canopy type lighting applications, for example to provide illumination under the canopy of a service station.
This embodiment comprises two opposing domes
613
and
619
of slightly different diameters supported at a distance from each other. Each dome may be substantially hemispherical. The inner surfaces of the domes
613
,
619
are diffusely reflective, as in the earlier embodiments. The upper dome
613
forms the base and is slightly larger in horizontal diameter than the lower dome
619
, which forms the mask for constructive occlusion purposes. The inner surface of the upper dome
613
forms a reflective cavity
615
in the shape of a segment of a sphere. The reflective interior
620
of the lower dome
619
could be considered as a cavity (similar to FIG.
3
), but for purposes of discussion here we will refer to the reflective interior region
620
as a reflector surrounding a portion of the light source.
A metal halide lamp
621
mounted between the inner surfaces of the domes serves as the light source. An electrical connector
622
extends through an opening in the upper dome
613
and provides a coupling for the metal halide lamp
621
to an appropriate power source (not shown).
The mask
619
takes the form of a second dome forming a reflector or second cavity
620
mainly to accommodate the size and shape of the preferred lamp, i.e. the metal halide lamp
621
(
FIG. 6
) at the location shown diagrammatically by the dotted-line oval
621
′ in the cross-section view of FIG.
7
. The system
611
may use the dome-shaped mask, a smaller dome or even a flat disk-shaped mask, if the designer elects to use a different type or size of light source. The combination of the cavity
615
and the deflector
620
, within the domes, closely approximates a spherical optical integrating cavity.
The system
611
also comprises three angled, circular plates
617
,
628
and
629
mounted to encircle the two domes
613
,
619
as shown. Each angled plate takes the form of a truncated, straight-sided cone. The cone formed by the lower plate
617
has its broad end down. The cone of the plate
628
has its broad end upward as does the cone of the plate
629
. The sidewall of the cone of the plate
628
preferably has a 10° angle relative to horizontal, and the sidewall of the cone of the plate
629
preferably has a 25° angle relative to horizontal.
The lower or inner surface of the plate
617
is reflective and serves as the shoulder formed about the constructive occlusion aperture
623
of the system
611
. The upper or inner surface of the plate
628
is reflective and serves as one wall of the expanding fan-shaped deflector
627
. The lower or inner surface of the plate
629
is reflective and serves as the other wall of the expanding fan-shaped deflector
627
. The reflective shoulder surface of the plate
617
preferably is specular, although materials providing a diffuse reflectivity or other type of reflectivity could be used on that surface. At least a substantial portion of each of the reflective surfaces of the deflector
627
has a specular reflectivity. Some sections of those surfaces may have a different reflectivity, such as a diffuse reflectivity adjacent the outer ends of the surfaces, for certain applications.
The junction between the plates
617
and
628
forms the aperture
623
. The space between that boundary and the lower edge of the plate
629
forms an annular port
625
formed in the wall of the base
613
to provide the optical coupling of the cavity
615
to the deflector
627
. In this embodiment, annular port
625
is adjacent to the aperture
623
. This position for the port is preferred, for ease of construction, but the annular pot could be at any elevation on the dome forming the base
613
and cavity
615
, to facilitate illumination of a second field or region at a particular angular range relative to the system
611
.
In this embodiment, the port
625
is formed along the boundary between the edge of the cavity
615
and the shoulder
617
. Consequently, the inner edge of the shoulder
617
actually defines the aperture
623
for constructive occlusion purposes with respect to the first region intended for illumination by the system. The aperture
623
is said to be the aperture of the base-cavity
615
and define the active optical area of the base
613
essentially as if the sides of the cavity
615
extended to the edges of the shoulder
617
(without the port).
Hence the cavity
615
, the aperture
623
, the mask
619
and the shoulder
617
provide constructive occlusion processing of a first portion of the light from the source
621
. The light emitted as a result of such processing provides a tailored intensity distribution for illumination of a first region, which is below the system
611
in the orientation shown. The relative dimensions of the aperture and mask, the distance of the mask from the aperture and size and angle of shoulder
617
determine the intensity distribution in this region, as in the earlier embodiments.
With respect to the port
625
, the diffusely reflective surfaces
615
and
620
inside the two domes
613
and
619
together approximate an optically integrating sphere. The integrating sphere processes light from the internal source
621
and provides an efficient coupling of such light through the port
625
.
The fan-shaped deflector
627
directs light emerging through the port
625
upward, away from the first (downward) field of intended illumination. In the illustrated example, the plates
628
and
629
form a limited second field of view for angles roughly between 10° and 25° above the horizontal. When measured with respect to the downward illumination axis of the system
611
as is used in lighting industry standards, this second field of illumination encompasses angles between 100° and 115°. Although some light passing through the port
625
is still directed outside the field of view defined by the deflector walls
628
,
629
, the reflective surfaces of the deflector
627
do channel most of the light from the port
625
into the area between the angles formed by those walls. As a result, the maximum intensity in the second illuminated region is between the angles defining the field of view of the deflector
627
.
In this embodiment, the fan-shaped deflector structure is angled so as to direct light away from the field illuminated by constructive occlusion. The two illuminated regions do not overlap at all. The plates
617
and
628
create a dead zone of no illumination between the two regions.
In use, the system
611
is mounted or hung under a canopy. The mounting may place the upper edge of the upper angled plate
629
of the deflector
627
at the surface of the underside of the canopy or a few inches below that surface.
FIG. 10
is a polar plot, and
FIG. 11
is a graph, of angle versus intensity showing the light distribution produced by the system
611
. In either illustration, the 0° angle represents the direction directly down along the vertical axis of the system
611
. The system
611
emits approximately 60% of the light energy upward, via the port
625
and the fan-shaped deflector structure
627
. The system
611
emits approximately 40% of the light downward, as processed by constructive occlusion. The emissions upward are separated from the downward emissions by a large dead zone around the horizon (90°). The dead zone prevents direct illumination of adjacent areas, for example on a nearby highway or in a house next-door to the gas station.
Because of the structure of the system, the light that otherwise would emerge undesirably in the dead zone is kept within the system and reprocessed by the reflective surfaces of the system, until it emerges into one or the other of the two desired fields of illumination. The system
611
therefore provides the desired lighting performance with a particularly high degree of efficiency.
The lighting system structure illustrated in
FIGS. 6-9
is round and symmetrical about a vertical system axis. For other applications, the design could be made rectangular or even linearized, in a manner similar to the embodiment of FIG.
4
.
In the embodiments discussed above, the systems have provided lighting in a symmetrical fashion on both sides of the system. Such constructions are appropriate for many down-lighting and up-lighting applications, where the system is mounted below a ceiling or canopy or mounted on a pole or other support in an open area. The concepts of the invention also encompass variations on the disclosed structures modified or “cut in half” by a reflective surface to facilitate wall mounting thereof.
To illustrate this principle,
FIGS. 12
to
14
relate to a cut-off version of the inventive system providing performance similar to that of the system of
FIGS. 6
to
9
.
FIG. 12
provides a front-side view of the wall-mounted system
711
.
FIG. 13
is a cross-section of the system
711
taken along line
13
—
13
of
FIG. 12
; and
FIG. 14
is a bottom plan view of the system.
This embodiment comprises two opposing half-domes
713
and
719
of slightly different diameters supported at a distance from each other. The back or cut-off side of each of the domes
713
,
719
abuts a surface of a reflective wall
730
. The inner surfaces of the domes
713
,
719
are diffusely reflective, as in the earlier embodiments. Within the domes, the surface of the wall
730
may be specular but preferably is diffusely reflective. The areas of the wall
730
outside the domes may have other reflectivities but preferably are specular.
The upper dome
713
forms the base and is slightly larger in size than the lower dome
719
, which forms the mask for constructive occlusion purposes. The inner surface of the upper dome
713
forms a reflective cavity
715
in the shape of approximately a quarter-segment of a sphere. The reflective interior
720
of the lower dome
719
could be considered as a cavity (similar to FIG.
3
), but for purposes of discussion here we will refer to the reflective interior region
720
as a reflector surrounding a portion of the light source. The reflector
720
also may take the shape of approximately a quarter-segment of a sphere. Although not shown in detail, the light source would be positioned approximately as shown by the dotted line at
721
in FIG.
13
. The source may be a florescent lamp, a metal halide lamp or other convenient source of radiant light energy.
The system
711
also comprises three angled, half-circular plates
717
,
728
and
729
mounted to extend from the wall
730
around the two domes
713
,
719
as shown. Each angled plate takes the forms half of a truncated, straight-sided cone. The lower or inner surface of the plate
717
is reflective and serves as the shoulder formed about the outer portion of the constructive occlusion aperture
723
of the system
711
. The upper or inner surface of the plate
728
is reflective and serves as one wall of the expanding fan-shaped deflector
727
. The lower or inner surface of the plate
729
is reflective and serves as the other wall of the expanding fan-shaped deflector
727
. The reflective shoulder surface of the plate
717
preferably is specular, and at least a substantial portion of each of the reflective surfaces of the deflector
727
has a specular reflectivity.
The junction between the plates
717
and
728
forms the aperture
723
. The aperture
723
is said to be the aperture of the base-cavity
715
and define the active optical area of the base
713
for constructive occlusion purposes essentially as if the sides of the cavity
715
extended to the edges of the shoulder
725
(without the port).
When viewed looking toward the reflective wall
730
, the system
711
looks essentially the same as the system
611
of the earlier embodiment (compare FIG.
8
). When viewed from below and somewhat to the right, the mirror-imaging of the system in the surface of the wall
730
makes the system appear as a full-circular system as in the earlier embodiment (with the dotted line half-portions appearing as mirror images within the wall). The light intensity distributions over the two illuminated regions produced by the system
711
are similar in profile to those produced by the system
611
except that they extend only to the right in the orientation shown (
FIGS. 13
,
14
). Assuming that the source produces the same amount or intensity of light for processing within the system
711
, the distributions produced over the one-sided regions will be approximately double the magnitude of the intensities produced by the fully circular system
611
.
The cavity
715
, aperture
723
, mask
719
and shoulder
717
provide constructive occlusion processing of a first portion of the light from the source
721
. The light emitted as a result of such processing provides a tailored intensity distribution for illumination of a first region, which is below the system
711
in the orientation shown. The relative dimensions of the aperture and mask, the distance of the mask from the aperture and size and angle of shoulder
717
determine the intensity distribution in this region. The reflectivity of the wall
730
essentially produces a mirror image of the physical elements of the system
711
, as shown in dotted line in
FIGS. 13 and 14
. Consequently, the system operates essentially as if it included the full circular components as in the preceding embodiment but reflects all of the light outward from the wall (to the right in FIG.
13
). This causes the system to distribute light in the first field of illumination with essentially the same profile as the earlier system but with almost double the intensity thereof because light that would emerge to the left is now reprocessed and directed downward to the right.
The space between the boundary of the plates
717
and
728
and the lower edge of the plate
729
forms an annular port
725
formed in the wall of the base
713
to provide the optical coupling of the cavity
715
to the deflector
727
. In this embodiment, the annular port
725
is adjacent to the aperture
723
, although the annular port could be at any elevation on the cavity
715
, to facilitate illumination of a particular field through the deflector
727
.
With respect to the port
725
, the diffusely reflective surfaces
715
and
720
inside the two domes
713
and
719
and the mirror-image reflections thereof by the surface of the wall
730
together form the equivalent of an optically integrating sphere. These optically integrating components process light from the internal source
621
and couple a substantial portion thereof through the port
725
. Because of the mirror-image effect of the wall
730
, the light emerging through the half-circular port
725
is almost double that emerging through the full circular port
625
in the preceding embodiment.
The fan-shaped deflector
727
directs light from the port
725
upward, away from the first (downward) field of intended illumination. Assuming that the plates
728
and
729
form a limited second field of view for angles roughly between 10° and 25° above the horizontal as in the earlier embodiment, the deflector
727
produces a similar intensity distribution over the second field of view, albeit doubled and covering only the half circular distribution to the right in the orientation of FIG.
13
. In particular, the fan structure provides a high intensity illumination over the second field of illumination that is separated from the first field of illumination by a substantial dead zone, as in the preceding embodiment.
In the illustrated example, the domes
713
,
719
and the wall
730
are separate elements, and the edges of the domes make relatively sharp corners where they abut the wall. Those skilled in the art will recognize that such a structure is somewhat idealized, for purposes of explanation. An actual implementation might involve formation of two or more of these elements from one common piece of material. In such an implementation, the corners, particularly those within the cavities would be rounded rather than the sharp corners illustrated. The system, however, would still perform substantially as discussed above.
Those skilled in the art will recognize that the inventive concepts disclosed above may be embodied in a variety of different practical structures to meet the lighting requirements of a wide range applications. For example, the size, shape and orientation of the cavities, the masks, the shoulders, the ports and the deflectors can be changed as needed to provide desired distribution of light over different footprints in each region illuminated. In some cases, to increase intensity in all or a part of one of the regions, a reflective “kicker” can be added in the form of a cone or baffle within the cavity of the system. Such a device tends to force more light out into a particular range of angles illuminated by the system.
Also, many of the deflectors have been shown with open ends projecting towards the desired fields of illumination. Although not shown, some applications may utilize a transparent cover over either the inner opening (at the port) or the outer opening of the deflector. Other applications may utilize some form of prism or lens at one or the other end of the deflector or at both ends of the deflector.
Furthermore, it may be desirable to have various combinations of multiple deflectors, such as one large deflector near the aperture and one or more smaller deflectors. Other applications may use fan deflectors at different elevations and/or angles coupled to the cavity and/or through the mask.
While the foregoing has described what are considered to be preferred embodiments of the invention it is understood that various modifications may be made therein and that the invention may be implemented in various forms and embodiments, and that it may be applied in numerous applications, only some of which have been described herein. It is intended by the following claims to claim all such modifications and variations which fall within the true scope of the invention.
Claims
- 1. A lighting system, comprising:a diffusely reflective optical-integrating cavity; a source coupled to emit light into the cavity; an elongated port extending along a portion of a perimeter of the cavity, for providing a passage for light from within the cavity; a first reflector mounted along the portion of the perimeter of the cavity, the first reflector having a reflective surface extending at a first angle from a first elongated edge of the port toward a region to be illuminated; a second reflector mounted along the portion of the perimeter of the cavity, the second reflector having a reflective surface extending at a second angle from a second elongated edge of the port toward the region to be illuminated; the reflective surfaces of the first and second reflectors forming a fan-shaped deflector coupled to the port and expanding outward as the reflective surfaces extend from the edges of the port toward the region to be illuminated, for directing the light from within the cavity over the region to be illuminated.
- 2. A lighting system as in claim 1, wherein the diffusely reflective optical-integrating cavity approximates an integrating sphere.
- 3. A lighting system as in claim 1, wherein the diffusely reflective optical-integrating cavity comprises two semi-spherical domes having diffusely reflective inner surfaces.
- 4. A lighting system as in claim 1, wherein the diffusely reflective optical-integrating cavity comprises two quarter-spherical domes having diffusely reflective inner surfaces and a reflective wall abutting edges of the domes.
- 5. A lighting system as in claim 1, wherein the diffusely reflective optical-integrating cavity comprises a base, a mask and a diffusely reflective cavity formed in the base or the mask configured to provide constructive occlusion illumination of another region.
- 6. A lighting system as in claim 1, further comprising:another port for providing a passage for light from within the cavity; and another deflector coupled to said another port for directing light from said another port over another region to be illuminated.
- 7. A lighting system as in claim 6, further comprising:a third port for providing a passage for light from within the cavity; and a third deflector coupled to said third port for directing light from said third port over a third region to be illuminated.
- 8. A lighting system, comprising:a cavity having a diffusely reflective inner surface and an aperture; a light source coupled to the cavity, for emitting light into an area within the cavity; a mask positioned outside the cavity at a distance from the aperture, the mask having a reflective surface optically facing the aperture, the mask constructively occluding the aperture of the cavity with respect to a first field of intended illumination, such that light reflected between the mask and cavity and emerging from a gap between the mask and the aperture illuminates a substantial portion of the first field of intended illumination with a desired intensity distribution pattern; a port extending from the diffusely reflective inner surface of the cavity toward a second field of intended illumination; and a reflector optically coupled to the port, for directing light emerging through the port toward the second field of intended illumination.
- 9. A lighting system as in claim 8, wherein the second field of intended illumination includes a substantial area outside the first field of intended illumination.
- 10. A lighting system as in claim 8, wherein the second field of intended illumination includes portion of the first field of intended illumination.
- 11. A system for projecting electromagnetic radiation with predetermined intensity over two distinct regions, comprising:a base having a defined area substantially facing a first region to be illuminated with the electromagnetic radiation, the defined area of the base having a reflective characteristic with respect to the electromagnetic radiation; a shoulder adjacent to and extending along a substantial portion of the defined area of the base, the shoulder having a surface with a reflective characteristic with respect to the electromagnetic radiation facing toward at least a portion of the first region to be illuminated; a mask between the base and the first region to be illuminated at a predetermined distance from the defined area of the base, said mask having a defined area substantially facing the defined area of the base, the defined area of the mask having a reflective characteristic with respect to the electromagnetic radiation; a source configured to emit the electromagnetic radiation for reflection between the defined areas of the base and mask, such that the base, mask and shoulder emit a substantial first portion of the electromagnetic radiation with a tailored intensity distribution of electromagnetic radiation over the first region to be illuminated; a port providing a radiation coupling from one of the defined areas toward a second region to be illuminated with the electromagnetic radiation; and a deflector having at least one reflective inner surface extending from a narrow end of the deflector coupled to the port to a wide end of the deflector directed toward the second region to be illuminated, such that a second portion of the electromagnetic radiation emerging through the port and deflector illuminates the second region.
- 12. A system as in claim 11, wherein the second region to be illuminated includes a substantial area outside the first region to be illuminated.
- 13. A system as in claim 11, wherein the second region to be illuminated includes a portion of the first region to be illuminated.
- 14. A system as in claim 11, wherein the second region to be illuminated is located entirely within the first region to be illuminated.
- 15. A system as in claim 11, wherein the defined area of the base comprises an aperture of a diffusely reflective cavity formed in the base.
- 16. A system as in claim 11, wherein the defined area of the mask comprises an aperture of a diffusely reflective cavity formed in the mask, and the defined area of the base comprises an area reflecting electromagnetic radiation emerging from the cavity through the aperture.
- 17. A system as in claim 11, wherein the surface of the shoulder is inclined at an angle from the defined area of the base toward the first region to be illuminated.
- 18. A system as in claim 11, wherein the deflector directs the second portion of the electromagnetic radiation away from the first region to be illuminated such that the shoulder and the deflector create a dead zone of little or no illumination by the system between the first and second regions.
- 19. A system as in claim 11, wherein:the port comprises an elongated opening extending along at least a portion of the periphery of the base; and the deflector forms a fan-shaped structure extending along the elongated opening.
- 20. A system as in claim 11, wherein the port extends from the defined area of the base toward the second region to be illuminated.
- 21. A system as in claim 11, wherein the port extends from the defined area of the mask toward the second region to be illuminated.
- 22. A system for projecting electromagnetic radiation, comprising:a source emitting the electromagnetic radiation; a base comprising a cavity optically coupled to receive the electromagnetic radiation from the source, the cavity having an inner surface with a substantially diffuse reflective characteristic with respect to the electromagnetic radiation and having an opening, a perimeter of the opening of the cavity forming an aperture substantially facing a first region to be illuminated with a first portion of the electromagnetic radiation; a shoulder adjacent to and extending along a substantial portion of the aperture, the shoulder having a surface with a reflective characteristic with respect to the electromagnetic radiation facing toward at least a portion of the first region to be illuminated; a mask between the base and the first region to be illuminated at a predetermined distance from the aperture, the mask having a surface area substantially facing the aperture which has a reflective characteristic with respect to the electromagnetic radiation, the mask having a relationship to the aperture such that the mask, cavity and shoulder provide a tailored intensity distribution of the first portion of the electromagnetic radiation over the first region; a port extending through the base from the cavity toward a second region to be illuminated with a second portion of the electromagnetic radiation, the second region including a substantial area outside the first region to be illuminated; and a deflector, having a reflective inner surface, extending from a narrow end coupled to the port to a wide end directed toward the second region to be illuminated.
- 23. A system for projecting electromagnetic radiation as in claim 22, wherein the source comprises a visible light source.
- 24. A system for projecting electromagnetic radiation as in claim 22, wherein at least a portion of the surface of the shoulder exhibits a substantially diffuse reflective characteristic.
- 25. A system for projecting electromagnetic radiation as in claim 22, wherein at least a portion of the surface of the shoulder exhibits a substantially specular reflective characteristic.
- 26. A system for projecting electromagnetic radiation as in claim 22, wherein the surface area of the mask substantially facing the aperture has a substantially diffuse reflective characteristic.
- 27. A system for projecting electromagnetic radiation as in claim 22, wherein at least a substantial portion of the inner surface of the deflector has a substantially specular reflective characteristic.
- 28. A system for projecting electromagnetic radiation as in claim 22, wherein the port and deflector are directed at such an angle away from the first region to be illuminated as to create a dead zone of substantially no illumination by the system between the first and second regions to be illuminated.
- 29. A system for projecting electromagnetic radiation as in claim 22, wherein the cavity is substantially hemispherical, and the port comprises an annular opening extending around the hemispherical cavity about an axis through the cavity, the aperture and the mask.
- 30. A system for projecting electromagnetic radiation as in claim 29, wherein the deflector forms a fan structure encircling the annular opening.
- 31. A system for projecting electromagnetic radiation as in claim 22, wherein the mask comprises a curved reflector for reflecting light from the source substantially toward the cavity.
- 32. A system for projecting electromagnetic radiation as in claim 31, wherein the source comprises a lamp mounted within a volume substantially enclosed by the cavity and the curved reflector.
- 33. A system for projecting electromagnetic radiation as in claim 22, further comprising:another port extending through the base from the cavity toward a third region to be illuminated with a third portion of the electromagnetic radiation; and another deflector having a reflective inner surface extending from a narrow end coupled to the other port to a wide end directed toward the third region to be illuminated.
- 34. A system for projecting electromagnetic radiation as in claim 33, wherein:the port comprises an elongated opening along a first side of the cavity; and the other port comprises an opening along a second side of the cavity substantially opposite the first side of the cavity.
- 35. A system as in claim 34, wherein each of the deflectors comprises a fan-shaped structure constructed along one of the elongated openings.
- 36. A system as in claim 34, wherein the inner surface of the cavity comprises a segment of a cylinder.
- 37. A system as in claim 36, wherein the source comprises a tubular lamp located between the mask and the inner surface of the cavity.
- 38. A system for projecting electromagnetic radiation, comprising:a source emitting the electromagnetic radiation; a base comprising a cavity optically coupled to receive the electromagnetic radiation from the source, the cavity having an inner surface with a substantially diffuse reflective characteristic with respect to the electromagnetic radiation and having an opening, a perimeter of the opening of the cavity forming an aperture substantially facing a first region to be illuminated with a first portion of the electromagnetic radiation; a port coupled to one of the defined areas and extending toward a second region to be illuminated with the electromagnetic radiation; and a deflector having at least one reflective inner surface extending from the port toward the second region to be illuminated, such that a second portion of the electromagnetic radiation emerging through the port and deflector illuminates the second region.
- 39. A system as in claim 38, wherein said at least one reflective inner surface of the deflector extends from a narrow end of the deflector coupled to the port to a wide end of the deflector directed toward the second region to be illuminated.
- 40. A system as in claim 38, wherein the deflector comprises a solid member providing total internal reflection from sides extending along the length of the solid member between an end coupled to the port and an end facing substantially toward the second region to be illuminated.
US Referenced Citations (8)