Patent Grant
8118451
The present patent application relates generally to light-emitting systems, and more particularly to such systems that employ reflective surfaces to produce adjustable lighting patterns.
Lighting systems for high-power light sources, such as light emitting diodes, can have a wide variety of configurations. In many cases, a particular configuration can be characterized by the illumination pattern it produces, by the coherence, intensity, efficiency and uniformity of the light projected by it, and so on. The application for which the lens and/or lighting system is designed may demand a high level of performance in many of these areas.
Many applications call for the ability to focus or change the size of a projected light spot. For example, flashlights, spotlights, and adjustable or customizable lighting systems, among others, all can utilize such focusing capabilities. However, creating a device that can provide such an adjustable lighting pattern is challenging. To date, lighting systems with focusing features have typically included single reflectors that can be moved with respect to the light source to change the size of a light spot projected onto a target surface. The capabilities of such systems are limited and their illumination characteristics are typically sub-optimal.
Accordingly, there is a need for improved lighting systems, and particularly those with adjustable focusing ability.
In one aspect, a lighting system is disclosed which comprises an inner reflector extending from a proximal end to a distal end along an axis, where the inner reflector is adapted to receive light from a light source at its proximal end. The lighting system also includes an outer reflector extending from a proximal end to a distal end through which light can exit the outer reflector. The proximal end of the outer reflector is optically coupled to the distal end of the inner reflector to receive light therefrom. Further, the inner and outer reflectors are coupled for axial movement relative to one another over a range of relative positions between a retracted position and an extended position, and the light exiting the outer reflector exhibits a progressively decreasing flood spread as the relative position of the reflectors is transitioned from said retracted position to said extended position.
In some embodiments, an axial overlap between the two reflectors is less in the extended position than in the retracted position. In the extended position, for example, the distal end of said inner reflector can axially abut the proximal end of said outer reflector. In some cases, the retracted position is characterized by a maximum axial overlap between the two reflectors within said range of relative positions, and the extended position is characterized by a minimum axial overlap between the two reflectors within said range of relative positions.
In some embodiments, the inner and outer reflectors of the lighting system can be configured such that an illumination area generated by light exiting the outer reflector exhibits a ratio of maximum to minimum intensity level of about 1.3:1 or less when said inner and outer reflectors are in said retracted position. Further, the inner and outer reflectors can be configured such that an illumination area generated by light exiting the outer reflector exhibits a ratio of maximum to minimum intensity level of about 10:1 or more when said inner and outer reflectors are in said extended position.
In another aspect, a lighting system is disclosed which comprises an inner reflector extending from a proximal end to a distal end along an axis, where the inner reflector is adapted to receive light from a light source at its proximal end. The lighting system also includes an outer reflector extending from a proximal end to a distal end through which light can exit the outer reflector. The proximal end of the outer reflector is optically coupled to the distal end of the inner reflector to receive light therefrom. Further, the inner and outer reflectors are coupled for axial movement relative to one another over a range of relative positions between a retracted position and an extended position. The inner and outer reflectors are configured such that an illumination area generated by light exiting the outer reflector exhibits a ratio of maximum to minimum intensity level of about 2:1 or less, or in other cases, of about 1.3:1 or 1.2:1 or less, when said inner and outer reflectors are in said retracted position and an illumination area generated by light exiting the outer reflector exhibits a ratio of maximum to minimum intensity level of about 10:1 or more, or in other cases about 20:1 or more, or about 30:1 or more, when said inner and outer reflectors are in said extended position.
In some embodiments, the illumination pattern generated when said inner and outer reflectors are in the extended position comprises a central region surrounded by an annular region and said ratio of maximum intensity level of about 10:1 or more (or in other cases, 20:1 or 30:1 or more) represents a ratio of intensity level of said central region relative to said annular region.
In some embodiments, an axial overlap between the two reflectors is less in the extended position than in the retracted position. In the extended position, for example, the distal end of said inner reflector can axially abut the proximal end of said outer reflector. In some cases, the retracted position is characterized by a maximum axial overlap between the two reflectors within said range of relative positions, and the extended position is characterized by a minimum axial overlap between the two reflectors within said range of relative positions.
In another aspect, a lighting system is disclosed that includes an inner reflector extending from a proximal end to a distal end along an axis, where the proximal end is adapted to receive light from a light source and the distal end provides an exit opening (aperture) for the received light. The system can further include an outer reflector that is axially positioned relative to the inner reflector. The outer reflector extends from a proximal end adapted to receive light from the light source to a distal end that provides an exit opening (aperture) for the received light. The inner and outer reflectors are axially movable relative to one another and are configured such that distal movement of the outer reflector (that is, a movement away from the inner reflector) along the axis about which the reflectors are disposed progressively reduces a flood spread produced by the lighting system. For example, a transition of the reflectors from a retracted position (e.g., a nested position) to an extended position can progressively reduce the flood spread produced by the lighting system.
In some embodiments, the inner and outer reflectors can be configured such that the distal movement of the outer reflector along the axis produces a central bright spot within an illumination pattern produced by the lighting system. In some embodiments, as the outer reflector is moved relative to the inner reflector (e.g., as the reflectors are transitioned from a retracted position to an extended position in a telescopic fashion), an increasing amount of the output light is concentrated within the central bright spot with the remaining light forming a lower intensity annulus about the central bright spot.
In another aspect, a lighting system is disclosed that includes an inner reflector extending from a proximal end to a distal end along an axis, and an outer reflector that is axially positioned relative to the inner reflector. The outer reflector extends from a proximal end adapted to receive light from the light source to a distal end that provides an exit opening for the received light. The inner and outer reflectors are axially movable relative to one another and are configured such that, for at least one relative position of the reflectors (e.g., an extended position), a maximum divergence angle relative to the axis exhibited by the light exiting the distal end of the inner reflector is more than a corresponding maximum divergence angle for the light exiting the distal end of the outer reflector.
In another aspect, the invention provides a lighting system that includes an inner reflector and an outer reflector that are coupled for movement relative to one another. In many embodiments, each of the inner and the outer reflector has inner and outer surfaces with the inner surface providing a reflective surface. The inner reflector is disposed about an axis for receiving light from a light source located along that axis and for reflecting at least some of that light. The inner reflector is configured such that the light exiting therefrom exhibits a first maximum divergence angle. The outer reflector is disposed axially relative to the inner reflector for receiving light from the light source and for reflecting at least a portion of that light. The outer reflector is configured such that the light exiting therefrom, for at least one relative position of the two reflectors along the axis (e.g., an extended position), exhibits a second maximum divergence angle, where the second divergence angle is less than the first divergence angle.
In the above lighting system, the inner and outer reflectors can be coupled for movement relative to one another between a retracted position, in which the outer reflector is entirely disposed proximal to the distal end of the inner reflector, and an extended position, in which at least a portion of the outer reflector is disposed distal to the inner reflector. In some cases, the inner reflector can be, in some positions, nested or disposed at least partially within the outer reflector. The inner and the outer reflectors can be coupled for telescopic movement relative to one another between an extended position and a retracted position. In some embodiments, in the extended position the inner and outer reflectors can be positioned so as to axially abut one another along their common axis (that is, with no or substantially no overlap) and can form a substantially continuous reflective surface. Further, in some embodiments, the inner and outer reflectors are substantially equal in height along their common axis.
In some embodiments, the outer reflector collimates light received from the light source for at least one position of the outer reflector along the axis.
In some embodiments, the light source can be disposed at a focal point of at least one of the inner or the outer reflector. For example, the light source can be attached to the inner reflector, e.g., such that the light source is fixedly disposed at the focal point of the inner reflector. In some cases, the light source can be disposed at a focal point of the outer reflector when the inner and the outer reflectors are in an extended position relative to one another.
In some implementations, at least one of the inner and the outer reflector has a parabolic profile. In other implementations, at least one of the inner reflector and the outer reflector comprises a faceted surface for reflecting at least a portion of the received light. By way of example, the faceted surface can comprise a plurality of sections having in may cases generally concave profile, e.g., a conical profile or any other suitable profile. In some cases, the faceted surface is configured such that movement of the faceted surface relative to a light source (e.g., an axial movement) can vary an illumination pattern generated by the lighting system. In some cases, the faceted surface can be asymmetric (e.g., rotationally or axially asymmetric) so that its movement (e.g., axial movement) causes an asymmetric variation of the illumination pattern generated by the lighting system.
A variety of light sources can be employed in the lighting systems of the invention. By way of example, the light source can comprise a light-emitting diode, a laser diode, a tungsten filament, a high intensity discharge lamp, a short arc lamp, a plasma arc lamp, etc.
In another aspect, an illumination device is disclosed that includes an inner reflector disposed about an axis for reflecting light from a light source located along the axis, where the reflection can be characterized by a first maximum divergence angle. The illumination device can further include an outer reflector disposed coaxially with the inner reflector for reflecting light from the light source, where the reflection from the outer reflector can be characterized by a second maximum divergence angle that is less than the first maximum divergence angle (e.g., for at least one relative position of the two reflectors). The inner and the outer reflector can cooperatively direct light from the light source to a target surface to form an illumination spot thereon. The device can further include an adjustment mechanism that is coupled to the inner reflector and the outer reflector for adjusting the relative positions of those reflectors and thereby changing the illumination spot. In some implementations, the adjustment mechanism can continuously adjust the relative positions of the inner and outer reflectors. In some other implementations, the adjustment mechanism can allow a user to select one relative position of the inner and outer reflectors amongst a discrete number of such positions.
The illumination device can include a housing in which the inner and the outer reflectors are disposed, where at least a portion of the housing forms a handle. A portable electric power source can be disposed in the housing for powering the light source, e.g., a light emitting diode. In some cases, the illumination device can be a flashlight.
In another aspect, a lighting system is disclosed that includes a lens disposed about an axis and optically coupled to a light source and an inner reflector that is disposed coaxially with the lens. The inner reflector can include an anterior surface and a posterior surface, where the posterior surface is configured to receive and reflect light from the lens. The lighting system can further include an outer reflector that is disposed coaxially with the inner reflector for receiving light reflected from the inner reflector and reflecting that received light, e.g., away from the lighting system and onto a target surface. The inner and the outer reflectors can be coupled for movement relative to one another. In some implementations, at least one of the lens and the inner reflector is disposed within the outer reflector.
In some implementations of the above lighting system, a relative movement of the inner reflector and the outer reflector away from one another can concentrate progressively more of the light rays leaving the lighting system into a central region. For example, more of the light rays can be concentrated onto a central bright spot of light projected onto a target surface.
In some implementations, the posterior surface of the inner reflector faces the lens. The posterior surface can be in the form of a tapered surface, e.g., one that is tapered to a point. Further, the outer reflector can have a parabolic profile having an inner reflective surface.
In another aspect, a lighting system is disclosed that includes a lens disposed about an axis and optically coupled to a light source, and an inner reflector disposed along the axis. The inner reflector can have distal and proximal surfaces, where the proximal surface is configured to receive light from the lens and reflect at least a portion of the received light. The lighting system can further include an outer reflector that is disposed along the axis for receiving light reflected from the inner reflector and reflecting at least a portion of that light, e.g., onto a target surface. The light source, the lens, the inner reflector, and the outer reflector are oriented with respect to one another such that light from the light source passes through the lens at least partially in a first direction, is reflected at least partially at the proximal surface of the inner reflector at least partially in a second direction that opposes the first direction (or, for example, that has a vector component that opposes the first direction), and is reflected at the outer reflector at least partially in the first direction.
In some embodiments, the inner and the outer reflector are movably coupled to one another such that their relative movement varies an output illumination pattern generated by the lighting system. For example, the reflectors can be disposed telescopically relative to one another such that a relative movement of the reflectors from a retracted position to an extended position reduces the flood spread and changes the uniformity of the light projected onto a target surface such that progressively more of the light is concentrated in a central region so as to provide a bright spot surrounded by a lower intensity region.
In some embodiments, in the above lighting system, at least one of the inner reflector and the outer reflector comprises a faceted surface for reflecting at least a portion of the received light. In some cases, the faceted surface can include a plurality of concave sections which can approximate a conical profile. In some cases, the faceted surface is configured such that its movement relative to the light source varies an output illumination pattern of the lighting system. In some cases, the faceted surface can be asymmetric (e.g., rotationally or axially asymmetric) such that its movement would cause an asymmetric variation in the output illumination pattern generated by the lighting system.
In another aspect, a lighting system is disclosed that includes a reflector extending from a proximal end to a distal end along an axis, where the proximal end is adapted to receive light from a light source and the distal end provides an exit opening for the received light. The reflector includes a first reflective region for receiving light from the light source located along the axis and for reflecting at least some of that light. The first reflective region is configured such that the light reflected therefrom exhibits a first maximum divergence angle. The reflector includes a second reflective region for receiving light from the light source and for reflecting at least some of that light. The second reflective region is configured such that the light reflected therefrom exhibits a second maximum divergence angle, where the second divergence angle is greater than the first divergence angle. In many cases, the first reflective region can be proximal to the second reflective region.
In some implementations of the above lighting system, the maximum divergence angles corresponding to the first and second reflective regions can have a difference in a range of about 8 degrees to about 60 degrees.
In some embodiments, one of the reflective regions can include a plurality of facets while the other reflective region has a smooth surface. The plurality of facets can be adapted to collectively reflect light incident thereon into an angular region. In some cases, the plurality of facets are adapted to collectively reflect light incident thereon to produce a substantially uniform output illumination area on a target surface.
In some embodiments, the lighting system can include a light source located along the axis, where the light source and the reflector are coupled for movement relative to one another. In some cases, the first reflective region is adapted to collimate light received from a light source located at a focal point thereof.
In another aspect, a lighting system is disclosed that includes a reflector extending from a proximal end to a distal end along an axis and having two or more differing reflective regions (e.g., a first region proximal to a second region). The proximal end of the reflector is adapted to receive light from a light source while its distal end provides an exit opening for the received light. The lighting system can further include a light source located along the axis, where the light source and the reflector are coupled for axial movement relative to one another, such that the relative distal movement of the light source (e.g., movement away from the proximal end of the reflector) along the axis progressively increases a flood spread produced by the lighting system.
In some implementations, at least one of the reflective regions is adapted to collimate light reflected thereby.
In some embodiments, at least one of the reflective regions can comprise a plurality of facets or can include a smooth inner surface. In some cases, at least one of the reflective regions comprises a plurality of facets and at least another reflective region comprises a smooth inner surface. In some cases, the facets are adapted to reflect light incident thereon into an angular region. In some cases, the facets are adapted to collectively reflect light incident thereon so as to produce a substantially uniform output illumination area on a target surface. The uniformity of the illumination area can be defined as the ratio of the maximum to the minimum light level within the illumination area. In some preferred embodiments, the light pattern generated by the lighting system, for at least one position of the light source relative to the reflector, can exhibit a uniformity of at least about 1.2:1.
A further understanding of various aspects of the invention can be obtained by reference to the following detailed description in conjunction with the associated drawings, which are discussed briefly below.
The present application relates generally to lighting or illumination systems and associated methods that employ one or more optical reflectors to generate a desired, typically adjustable, light pattern. Such devices and methods can be used with a wide variety of light sources, including light-emitting-diodes and incandescent bulbs. Such devices and methods can have wide application, including, for example, in flashlights, spot lighting, customizable/adjustable lighting systems, household lighting, wearable headlamps or other body-mounted lighting, among others. Further, they can be useful in applications requiring illumination in conditions of degraded visibility, such as underwater lighting, emergency services lighting (e.g., firefighter headlamps), or military applications.
As will be described in more detail below, some embodiments can advantageously produce a relatively narrow beam to illuminate an object (in some cases, illuminating an object at a long distance, in conditions of degraded visibility, or otherwise) while providing a surrounding illumination that is relatively uniform (for example, to provide context or peripheral vision, such as when spotlighting an actor on a stage, or when illuminating a narrow footpath and the vegetation at its edges). For example, some embodiments can advantageously provide the ability to adjust the lighting pattern from a relatively narrow to a relatively wide beam pattern (and vice versa), with the wide beam providing a different illumination pattern (for example, a wide beam of relatively uniform illumination) than the narrow beam.
Throughout this specification, the term “e.g.” will be used as an abbreviation for the non-limiting phrase “for example.” The term “reflector” as used herein refers to an optical component that includes at least one reflective surface, e.g., a surface that can cause specular reflection of light incident thereon. In many cases, the reflective surface can exhibit a reflectance greater than about 80%, preferably greater than about 85% or 90% or 95% or about 100%, in the visible range of the electromagnetic spectrum, e.g., for wavelengths in a range of about 400 nm to about 700 nm.
In one embodiment, an exemplary lighting system generally can include an inner reflector and an outer reflector coaxially disposed along an axis. The inner reflector can have a proximal end adapted to receive light from a light source (e.g., one that is fixedly attached thereto), and a distal end through which the light exits the reflector. Similarly, the outer reflector can have a proximal end adapted to receive light (e.g., directly from a light source or via reflection from the inner reflector) and a distal end through which the light exits the reflector.
The inner and outer reflectors can be configured to move relative to one another along the axis (e.g., from a retracted position to an extended position). In some embodiments, in a retracted position, the outer reflector can circumferentially surround or overlap the inner reflector such that the distal end of the outer reflector is withdrawn proximal to the distal end of the inner reflector. In such a position, the inner reflector can produce an illumination pattern on a target surface which exhibits a particular flood spread. The flood spread, for example, can be characterized by the maximum divergence angle of light rays exiting the lighting system relative to the optical axis of the lighting system. As the outer reflector moves distally along the axis (e.g., such that an increasing portion of the outer reflector is disposed distal to the distal end of the inner reflector with a concomitant decrease in the axial overlap between the reflectors, and can receive light from the inner reflector and/or light source), the outer reflector can progressively reduce the flood spread of light exiting the lighting system.
In some cases, the flood spread of the lighting system (the spread of light rays exiting the lighting system) for a given position of the reflectors can be characterized by the light spot produced on a target surface, as shown for example in
In many cases, the outer reflector can reduce flood spread by redirecting (e.g., reflecting) at least some of the light received from the inner reflector and/or the light source. For example, the outer reflector can redirect light received from the light source towards an optical axis (e.g., a central axis of the lighting system), and/or can redirect light substantially parallel to the axis. As the outer reflector is moved distally, it can redirect an increasing amount of light, thereby reducing flood spread and/or creating a central bright spot.
Turning to
The inner and outer reflectors 12, 14 can be movable or adjustable relative to one another, as shown in the progression from
The inner and outer reflectors 12, 14 can have a variety of shapes, but in some embodiments, the inner and outer reflectors can be conoidal (for example, they can be shaped like a cone and/or have a two-dimensional profile that is a conic section, such as a parabola, cone, ellipse, etc.). In many embodiments, the reflectors can be paraboloids. In yet other embodiments, the inner and outer reflectors 12, 14 can be substantially U-shaped or V-shaped in profile. As shown in
In many embodiments, the inner and outer reflectors can be shaped and configured such that, for at least one position of the light source (e.g., the extended position, or others), the light (including both reflected and un-reflected light) exiting the inner reflector 12 exhibits a maximum angle of divergence that is greater than the maximum angle of divergence of light exiting the outer reflector. In some preferred embodiments, the relative ratio of the heights of the reflectors 12, 14 can be about 3.4:1 (the outer reflector 14 has the greater height) with an exit aperture diameter ratio of about 1.85:1 (with the inner reflector 12 having the greater diameter).
In other embodiments, the outer and inner reflectors 12, 14, can reflect light at the same or a similar maximum divergence angle. In some embodiments, the outer reflector 14 is configured and positioned relative to the light source 18 so as to reflect the light from the source incident thereon in a collimated fashion for certain of its axial positions relative to the light source 18. For example, in the case of a parabolic outer reflector in an axial position at which the light source 18 is at a focal point of the paraboloid, the light rays reflected by the outer reflector 14 are substantially collimated.
The light source 18 can have a wide variety of locations, including both on-axis and off-axis locations, as previously mentioned. However, in many embodiments the light source can be attached to inner reflector such that it is disposed at a focal point thereof. In such a case, the light source can be also disposed at the focal point of the outer reflector for at least one position of the outer reflector, such as when the outer reflector is at the extended position. In other embodiments, the light source can be attached to the outer reflector so that it is disposed at a focal point thereof. Although shown as a light-emitting diode in
Returning again to
The illumination pattern produced in such an extended position can have a central bright spot surrounded by a diffuse annular region of light. In some cases, the central bright spot can be produced at least in part by the light reflected by the outer reflector 14 (again, by light reflected so as to have a smaller divergence), while the annular region can be produced at least in part by the light escaping the inner and outer reflectors 12, 14 without reflection therefrom.
As previously mentioned, the inner and outer reflectors 12, 14 can be adjusted to an exemplary intermediate position shown in
Further, the inner and outer reflectors can be adjusted to the retracted position shown in
The relative dimensions of the inner and outer reflectors 12, 14 can vary widely. However, in many embodiments, the width or diameter of the opening of the outer reflector 14 at its proximal end 24 can be sized such that inner reflector 12 can be received therethrough to allow the inner and outer reflectors 12, 14 to move in a telescopic fashion, as illustrated by
As previously mentioned in connection with
It should be understood that the parameters listed above are merely provided as illustrations of designs and are not intended to necessarily show optimal results that can be achieved or that need to be achieved by employing a lighting system in accordance with the teachings of this application.
It should be understood that the relative positions designated as “extended”, “intermediate”, and “retracted” in connection with
In some embodiments, the inner and the outer reflectors 12, 14 are configured and the light source 18 is positioned relative to the reflectors such that in a fully retracted position, the lighting system 10 can generate an output illumination area (e.g., on a target surface) across which the light intensity level is highly uniform. In many embodiments, the illumination area can be characterized by the illuminated target surface area bounded by rays exiting the lighting system at a maximum divergence angle (e.g., the maximum angle at which rays can exit without reflection) to the optical axis. Such rays can characterize a solid angle extending from the light source and being subtended by the illumination area. For example, the ratio of maximum to minimum light intensity level across the illumination area when the reflectors are in a fully retracted position can be equal or less than about 2:1, preferably about 1.3:1 or less, in some cases about 1.2:1 or less, and in some cases the ratio can be about one. As the reflectors 12, 14 are transitioned from the fully retracted position to the fully extended position, the lighting system 10 directs progressively more of the light to a central spot within the illumination area. In some embodiments, in the fully extended position, the ratio of maximum to minimum light intensity level across the illumination area (e.g., from a central point to a peripheral point) can be equal to or greater than about 10:1, or about 20:1, or about 30:1. Further, a normalized uniformity can be defined as the ratio of maximum and minimum light intensity where:
As one of ordinary skill in the art will understand, the above-recited uniformity ratios (e.g., 2:1 in a retracted position and 10:1 in an extended position) generally can be expressed as a normalized uniformity between 0 and 1. For example, if max=1 and min=1, then the normalized uniformity is 1, while if max=2 and min=1, then the normalized uniformity is 0.5, and if max=10 and min=1, then the normalized uniformity is 0.9.
In some implementations, in the retracted position, the reflectors are sized and the light source is positioned relative the proximal end of the inner reflector such that a substantial portion of the light emitted by the source (e.g., more than about 80% or preferably more than about 90% and in some cases 100%) that enters the inner reflector exits the distal end of the outer reflector without undergoing any reflections by the outer reflector, and in many cases without undergoing any reflections by the inner reflector either. In other words, a substantial portion of the light emitted by the source can be directly projected onto a target surface.
A wide variety of adjustment mechanisms can be used to move the reflectors relative to one another. Preferably, the relative movement of the reflectors is along a common axis, as depicted in
The inner reflector 104 generally can have a tapered shape, (and/or can be conoidal, as mentioned previously) and can have anterior and posterior surfaces 96, 98. At least the posterior surface 98 can be configured to reflect light therefrom. The lens 102 can have a wide variety of shapes, but as shown the lens 102 can be configured to receive light from the light source 100 and to pass or couple such light to the inner reflector 104. The lens 102 can be formed from polycarbonate or any of a wide variety of materials.
In use, as illustrated by an exemplary ray trace 110 in
Further, in many embodiments, the outer reflector 106 can be movable or adjustable relative to an assembly of the inner reflector 104, lens 102, and light source 100, which can be fixedly attached to one another. (It should be understood, however, that any of the components can be movable or adjustable relative to one another depending on the desired adjustment mechanism and illumination characteristics.)
It should be understood that while for descriptive purposes many of the foregoing embodiments have included two reflectors, virtually any number of reflectors can be used. For example,
As shown in
In many embodiments, the inner surface of distal region 1402a can be adapted to produce a flood beam on a target plane, which can be wider (e.g., on the target plane) than the light spot produced by collimated or collected light from the proximal region 1402a. In many cases, for a given position of the light source 1410 (e.g., the light source 1410 can be disposed at a focal point of reflector region 1402b), the maximum divergence angle between the axis 1404 and a light ray reflected from region 1402a can be greater than that of the maximum divergence angle between the axis 1404 and a light ray reflected from region 1402b.
For example, the distal region 1402b can have a generally parabolic or other shape and can be faceted. Each of a plurality of facets 1412 can redirect at least a portion of light incident thereon into an angular region 1414. In many embodiments, the angular region 1414 can extend from a ray that is substantially parallel to the optical axis 1404 to another ray which is reflected at maximum angle (e.g., a chosen angle depending on the desired illumination characteristics), which is shown in more detail with arrow 1450 in
In use, for a given position of the light source 3510, light reflected from proximal reflective region 1402b can be directed into a central bright spot on a target surface, while light reflected from distal portion 1402a can produce a substantially uniform light distribution on the target surface (e.g., from the superposition of reflected rays as previously described), which can illuminate an area larger than the central bright spot.
The light source 1410 and/or the reflector 1402 can be moved along axis 1404 to change their relative axial positions and thereby vary the light pattern produced. By way of illustration, in some embodiments the light source 1410 can initially be disposed as shown in
Conversely, as the position of the light source 3510 relative to the reflector 1402 is changed from
The relative sizes of the regions 1402a and 1402b along the axis 1404 (e.g., their relative lengths along the axis 1404) can be adjusted to proportion the amount of light reflected from the proximal and distal regions 1402a, 1402b and to thereby vary the light pattern produced for a given position of the light source 1410. For example, adjusting the relative sizes of the regions 1402a and 1402b can balance the peak luminance (e.g., at a given target distance) with the size and uniformity of the flood beam. In some embodiments, the ratio of the heights of the two regions can be in a range of about 2.5:1 to about 6:1 with the height ratio of about 3.4:1 being the preferred height in some implementations of the reflector.
Although
By way of further illustration, the following Examples 1-4 are provided. It should be understood that the information presented in connection with the Examples is provided for illustrative purposes and is not intended to necessarily show optimal results that can be achieved or that need to be achieved by employing a lighting system in accordance with the teachings of this application.
For illustrative purposes, a prototype lighting system was fabricated with some similar features as those described in connection with the embodiments shown in
A Cree XR White LED (100 LM flux) was attached to the inner reflector such that it would be oriented at the focal point of the inner reflector and of the outer reflector when the outer reflector was in an extended position. The light source was fixedly attached to the inner reflector, and the inner and outer reflectors were mounted for relative co-axial movement. More specifically, the inner and outer reflectors were coupled so that the outer reflector could be moved relative to the fixed inner reflector and the LED. The outer reflector could overlap the inner reflector as it retracted. The travel distance of the outer reflector between the extended or narrow position and the retracted or wide position was about 15 mm.
A prototype two-reflector focusable lighting system based on the teachings of the invention was designed.
Design Method/Details:
The Example 2 design was performed using the following steps:
System Setup for Simulation of Example 2:
Some of the optical characteristics of the prototype system, which were obtained theoretically (via simulation), are summarized in Table 1 below:
The on-axis efficiency indicates the efficiency of light collection within a central measurement point in candelas/lumen and can be described as:
The following is a description of an exemplary design process for creating uniform lighting via the use of controlled facets as indicated in Example 2:
1. Lighting Area
2. Base Curve
3. Uniformity Considerations
4. Segmenting Base Curve
5. Build Up Facet Segments
6. Creation of 2nd Axis
7. Revolution of Facet Column
8. Final 3D Model
Based on the design results presented in Example 2, a prototype was fabricated for verification of the design intent.
System Setup:
The reflectors were formed of polycarbonate with their inner surfaces metalized via a vacuum aluminum metallization process to provide reflective surfaces. Both reflectors had generally paraboloid profiles. While the inner reflective surface of the outer reflector was smooth, the inner reflective surface of the inner reflector included a plurality of facets.
Some of the optical performance characteristics of the prototype, which were obtained experimentally from the fabricated device, are listed in Table 2 below:
The prototype lighting system provided excellent narrow-beam and very good wide-beam aesthetic quality as well as very high efficiency (in calculating the efficiency, a factor of 0.9 was assumed to account for cover window losses). The on-axis performance of the narrow beam is equal or better than production products of similar size.
By way of illustration,
With reference to
The reflector was designed for high volume manufacturing suitable for a variety of applications, such as consumer, industrial and military applications. The reflector was designed to be fabricated via molding of polycarbonate material (in other implementations other materials such as polymethylmethacrylate (PMMA), polystyrene, ultem can be employed). The inner surfaces of the reflector were designed to be metalized with aluminum (in other implementations other metals can be employed) to provide reflective surfaces exhibiting a minimum reflectivity of about 85% to redirect the light incident thereon. The design was such that in many applications, the reflector can be adjusted by the end user to change the size of projected light spot.
Design Method/Details:
In this Example 4, the design of the prototype lighting system was performed using the following steps:
Beam Pattern vs. Reflector Position to LED:
Any of the reflectors and lenses described in this application, including the foregoing Examples 1-4, can be made of polymethyl methacrylate (PMMA), glass, polycarbonate, cyclic olefin copolymer and cyclic olefin polymer, or any other suitable material. By way of example, the reflectors can be formed by injection molding, by mechanically cutting a reflector or lens from a block of source material and/or polishing it, by forming a sheet of metal over a spinning mandrel, by pressing a sheet of metal between tooling die representing the final surface geometry including any local facet detail, and so on. Reflective surfaces can be created by a vacuum metallization process which deposits a reflective metallic (e.g., aluminum) coating, by using highly reflective metal substrates via spinning or forming processes. Faceting on reflector surfaces can be created by injection molding, by mechanically cutting a reflector or lens from a block of source material and/or polishing it, by pressing a sheet of metal between tooling die representing the final surface geometry including any local facet detail, and so on.
Any appended claims are incorporated by reference herein and are considered to represent part of the disclosure and detailed description of this patent application. Moreover, it should be understood that the features illustrated or described in connection with any exemplary embodiment may be combined with the features of any other embodiments. Such modifications and variations are intended to be within the scope of the present patent application.
The present application claims priority to a U.S. provisional application entitled “Reflective Variable Spot Size Lighting System” having a Ser. No. 61/036,359 and filed on Mar. 13, 2008, a U.S. provisional application entitled “Reflective Variable Spot Size Lighting Devices and Systems” having a Ser. No. 61/050,835 and filed May 6, 2008, a U.S. provisional application entitled “Reflective Variable Spot Size Lighting Devices and Systems” having a Ser. No. 61/059,889 and filed Jun. 9, 2008, and a U.S. provisional application entitled “Reflective Variable Spot Size Lighting Devices and Systems” having a Ser. No. 61/097,750 and filed on Sep. 17, 2008. All of the foregoing provisional applications are herein incorporated by reference.
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