VARIABLE-BEAM LIGHT SOURCE AND RELATED METHODS
Light sources with arrangements of multiple LEDs (or other light-emitting devices) disposed at or near the focus of a reflecting optic and controllable individually or in groups facilitate varying the angular distribution of the light beam (e.g., the beam divergence) via the drive currents supplied to the LEDs.
1 . A light source producing a beam of variable divergence, comprising:
(a) a concave reflecting optic;
(b) an arrangement of light-emitting devices disposed fixedly relative to and oriented to face in the same direction as the reflecting optic, light emitted by the light-emitting devices and reflected by the optic forming a light beam; and
(c) driver circuitry for controlling drive currents to the light-emitting devices individually or in groups thereof to thereby variably control a divergence of the light beam.
2 . The light source of claim 1 , wherein the arrangement of light-emitting devices is disposed substantially at a focus of the reflecting optic.
3 . The light source of claim 1 , wherein the light-emitting devices comprise LEDs.
4 . The light source of claim 1 , wherein the reflecting optic is at least one of faceted or textured.
5 . The light source of claim 1 , wherein the reflecting optic comprises a parabolic reflector.
6 . The light source of claim 5 , wherein the arrangement of light-emitting devices is disposed substantially at a focal plane of the parabolic reflector.
7 . The light source of claim 1 , wherein a diameter of the reflecting optic is greater than a largest dimension of the arrangement of light-emitting devices.
8 . The light source of claim 7 , wherein the diameter of the reflecting optic is at least twice as large as the largest dimension of the arrangement of light-emitting devices.
9 . The light source of claim 1 , wherein a largest dimension of the arrangement of light-emitting devices is greater than a focal length of the reflecting optic.
10 . The light source of claim 9 , wherein the largest dimension of the arrangement of light-emitting devices is at least twice as large as the focal length of the reflecting optic.
11 . The light source of claim 1 , wherein the circuitry is configured to control the drive currents to the light-emitting devices based on their distance from a center of the arrangement.
12 . The light source of claim 11 , wherein the circuitry is configured to narrow the beam by providing non-zero drive currents only to light-emitting devices within a specified distance from the center.
13 . The light source of claim 1 , wherein the circuitry is configured to further uniformly vary the drive currents to all light-emitting devices to thereby vary the intensity of the beam.
14 . The light source of claim 1 , wherein the circuitry is configured to selectively drive a subset of the light-emitting devices so as to generate a pattern.
15 . The light source of claim 1 , wherein the circuitry is programmable.
16 . The light source of claim 1 , wherein the circuitry is configured to control the drive currents based on at least one of sizes or positions of respective light-emitting devices.
17 . The light source of claim 1 , wherein a light-emitting device located at a center of the arrangement is a higher-power device than a light-emitting device located at a periphery of the arrangement.
18 . The light source of claim 1 , wherein the arrangement of the light-emitting devices is planar.
19 . A method of varying divergence of a light source comprising a concave reflecting optic and, disposed fixedly relative to and oriented to face in the same direction as the reflecting optic, an arrangement of light-emitting devices controllably individually or in groups, the method comprising:
driving the light-emitting devices so as to create a light beam emerging from the focusing optic; and
controlling the drive currents to the light-emitting devices, individually or in groups thereof, based, at least in part, on the distance of the devices from a center of the arrangement so that the beam has a divergence variably determined by the controlled drive currents.
20 . The method of claim 19 , wherein the light-emitting devices comprise LEDs.
21 . The method of claim 19 , wherein the reflecting optic comprises a parabolic reflector.
22 . The method of claim 19 , wherein controlling the drive currents comprises decreasing the drive currents to LEDs in an outer region of the arrangement to thereby narrow the beam.
23 . The method of claim 19 , further comprising simultaneously and uniformly varying the drive currents to all LEDs to thereby vary the beam brightness.
24 . The method of claim 19 , further comprising programming driver circuitry controlling the drive currents.