Systems and methods for a high output, high color quality light are disclosed. In some embodiments, such a light may include a light fixture including one or more leds configured to output a cumulative light output; wherein the cumulative light output comprises an intensity of greater than or equal to 10,000 lumens; and wherein the cumulative light output comprises a CRI of at least 90.
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0. 66. A light fixture comprising:
a plurality of leds that provide a cumulative light output comprising an intensity of greater than or equal to 10,000 lumens and a color rendering index (CRI) of at least 90, the plurality of leds comprising two or more strings of leds, the two or more strings of leds comprising a first string of leds and a second string of leds connected in parallel with the first string of leds;
a current source that provides a drive current comprising at least 700 mA to the plurality of leds;
a first current control device connected in series with the first string of leds;
a second current control device connected in series with the second string of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device.
0. 32. A light fixture comprising:
a plurality of leds that provide a cumulative light output comprising an intensity of greater than or equal to 10,000 lumens and a color rendering index (CRI) of at least 94, the plurality of leds comprising two or more strings of leds, the two or more strings of leds comprising a first string of leds and a second string of leds connected in parallel with the first string of leds;
a first current control device connected in series with the first string of leds that provides a drive current comprising at least 700 mA to the plurality of leds;
a second current control device connected in series with the second string of leds and configured to control the drive current provided to the plurality of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device.
0. 39. A light fixture comprising:
a plurality of leds configured to output a cumulative light output, the plurality of leds comprising two or more strings of leds, the two or more strings of leds comprising a first string of leds and a second string of leds connected in parallel with the first string of leds;
a first current control device connected in series with the first string of leds and configured to control a drive current provided to the plurality of leds, wherein the drive current comprises at least 700 mA;
a second current control device connected in series with the second string of leds and configured to control the drive current provided to the plurality of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device, wherein the cumulative light output comprises an intensity of greater than or equal to 10,000 lumens and a color rendering index (CRI) of at least 90.
0. 54. A light fixture comprising:
a plurality of leds configured to output a cumulative light output at an efficiency, the plurality of leds comprising two or more strings of leds, the two or more strings of leds comprising a first string of leds and a second string of leds connected in parallel with the first string of leds;
a first current control device connected in series with the first string of leds and configured to control a drive current provided to the plurality of leds, wherein the drive current comprises at least 700 mA;
a second current control device connected in series with the second string of leds and configured to control the drive current provided to the plurality of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device, wherein the cumulative light output comprises an intensity of greater than or equal to 10,000 lumens and a color rendering index (CRI) of at least 90.
13. A light fixture comprising:
a plurality of leds configured to output a cumulative light output at an efficiency, the plurality of leds comprising two or more strings of leds, the two or more strings of leds comprising a first string of leds and a second string of leds connected in parallel with the first string of leds;
a first current control device connected in series with the first string of leds and configured to control a drive current provided to the plurality of leds, wherein the drive current comprises at least 700 mA; and
a second current control device connected in series with the second string of leds and configured to control the drive current provided to the plurality of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device;
wherein the cumulative light output comprises an intensity of greater than or equal to 10,000 lumens and a color temperature of greater than or equal to 4000° K color rendering index (CRI) of at least 90.
1. A light fixture comprising:
a plurality of leds configured to output a cumulative light output, the plurality of leds comprising two or more strings of leds, at least two of the two or more strings of leds comprising different color leds, the two or more strings of leds comprising a first string of leds and a second string of leds connected in parallel with the first string of leds;
a first current control device connected in series with the first string of leds and configured to control a drive current provided to the plurality of leds, wherein the drive current comprises at least 700 mA; and
a second current control device connected in series with the second string of leds and configured to control the drive current provided to the plurality of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device;
wherein the cumulative light output comprises an intensity of greater than or equal to 10,000 lumens and a color temperature of greater than or equal to 4000° K color rendering index (CRI) of at least 94.
0. 2. The light fixture of
0. 3. The light fixture of
4. The light fixture of claim 3 1, wherein at least one of the strings comprises a Blue Shifted Yellow string and at least one of the strings comprises a Red string.
5. The light fixture of claim 3 1, wherein each of the strings comprises a Blue Shifted Yellow string with a different color temperature.
0. 6. The light fixture of
a first current control device connected in series with the first string of leds;
a second current control device connected in series with the second string of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device.
7. The light fixture of claim 6 1, wherein each of the first and second current control devices comprise: a Bipolar Junction Transistor (BJT); a MOSFET; a junction gate field-effect transistor (JFET); or an insulated gate field effect transistor (IGFET).
8. The light fixture of
9. The light fixture of claim 6 1, further comprising a third string of leds connected in series with the first and second string of leds.
10. The light fixture of claim 6 1, further comprising:
a pulse generator;
an RC circuit coupled to the pulse generator; and
a third current control device coupled to the RC circuit, the third current control device configured to vary the voltage measured by the second voltage measurement device.
11. The light fixture of
a plurality of heat-sink-mounted led array modules, each module engaging an led-adjacent surface of a heat-sink base for transfer of heat from the module;
a heat-sink heat-dissipating surface extending away from the modules;
at least one venting aperture through the heat-sink base to provide air ingress to the heat-dissipating surfaces adjacent to the aperture.
12. The light fixture of
a housing and an led assembly secured with respect thereto and open to permit air/water-flow over the led assembly, the led assembly comprising:
an led-array;
an extruded heat sink that has a base and heat-transfer surfaces extending from the base, wherein the heat-transfer surfaces are surfaces of a plurality of fins extending away from the base in a first direction, the fins including first and second fins along the opposite edges of the base, the first and second edge-adjacent fins also extending from the base in a second direction opposite to the first direction.
0. 14. The light fixture of
0. 15. The light fixture of
a first current control device connected in series with the first string of leds;
a second current control device connected in series with the second string of leds;
a first voltage measurement device coupled to the first string of leds and the second string of leds, the first voltage measurement device coupled to the first current control device and configured to control the first current control device; and
a second voltage measurement device coupled to the first string of leds and the second string of leds, the second voltage measurement device coupled to the second current control device and configured to control the second current control device.
16. The light fixture of claim 15 13, wherein each of the first and second current control devices comprise: a Bipolar Junction Transistor (BJT); a MOSFET; a junction gate field-effect transistor (JFET); or an insulated gate field effect transistor (IGFET).
17. The light fixture of
18. The light fixture of claim 15 13, further comprising a third string of leds connected in series with the first and second string of leds.
19. The light fixture of claim 15 13, further comprising:
a pulse generator;
an RC circuit coupled to the pulse generator; and
a third current control device coupled to the RC circuit, the third current control device configured to vary the voltage measured by the second voltage measurement device.
20. The light fixture of
a plurality of heat-sink-mounted led array modules, each module engaging an led-adjacent surface of a heat-sink base for transfer of heat from the module;
a heat-sink heat-dissipating surfaces extending away from the modules;
at least one venting aperture through the heat-sink base to provide air ingress to the heat-dissipating surfaces adjacent to the aperture.
21. The light fixture of
a housing and an led assembly secured with respect thereto and open to permit air/water-flow over the led assembly, the led assembly comprising:
an led-array;
an extruded heat sink that has a base and heat-transfer surface extending from the base, wherein the heat-transfer surfaces are surfaces of a plurality of fins extending away from the base in a first direction, the fins including first and second fins along the opposite edges of the base, the first and second edge-adjacent fins also extending from the base in a second direction opposite to the first direction.
22. The light fixture of
23. The light fixture of
24. The light fixture of
25. The light fixture of
26. The light fixture of
27. The light fixture of
28. The light fixture of
29. The light fixture of
30. The light fixture of
31. The light fixture of
0. 33. The light fixture of claim 32, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens.
0. 34. The light fixture of claim 32, wherein the drive current comprises from 700 mA to 1000 mA.
0. 35. The light fixture of claim 32, wherein the cumulative light output comprises a total radiant flux from 30,900 mW to 41,600 mW.
0. 36. The light fixture of claim 32, wherein the cumulative light output comprises a color temperature of greater than or equal to 4000° K.
0. 37. The light fixture of claim 32, wherein the cumulative light output comprises a color temperature of greater than or equal to 5000° K.
0. 38. The light fixture of claim 32, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens, and the drive current comprises a current from 700 mA to 1000 mA.
0. 40. The light fixture of claim 39, wherein at least two of the two or more strings of leds comprise different color leds.
0. 41. The light fixture of claim 40, wherein at least one of the strings comprises a Blue Shifted Yellow string and at least one of the strings comprises a Red string.
0. 42. The light fixture of claim 40, wherein each of the strings comprises a Blue Shifted Yellow string with a different color temperature.
0. 43. The light fixture of claim 39, wherein each of the first and second current control devices comprise: a Bipolar Junction Transistor (BJT); a MOSFET; a junction gate field-effect transistor (JFET); or an insulated gate field effect transistor (IGFET).
0. 44. The light fixture of claim 43, wherein each of the first and second voltage measurement devices comprise: a comparator and an op-amp.
0. 45. The light fixture of claim 39, further comprising a third string of leds connected in series with the first and second string of leds.
0. 46. The light fixture of claim 39, further comprising:
a pulse generator;
an RC circuit coupled to the pulse generator; and
a third current control device coupled to the RC circuit, the third current control device configured to vary the voltage measured by the second voltage measurement device.
0. 47. The light fixture of claim 39, further comprising:
a plurality of heat-sink-mounted led array modules, each module engaging an led-adjacent surface of a heat-sink base for transfer of heat from the module;
a heat-sink heat-dissipating surface extending away from the modules;
at least one venting aperture through the heat-sink base to provide air ingress to the heat-dissipating surfaces adjacent to the aperture.
0. 48. The light fixture of claim 39, further comprising:
a housing and an led assembly secured with respect thereto and open to permit air/water-flow over the led assembly, the led assembly comprising:
an led-array;
an extruded heat sink that has a base and heat-transfer surfaces extending from the base, wherein the heat-transfer surfaces are surfaces of a plurality of fins extending away from the base in a first direction, the fins including first and second fins along the opposite edges of the base, the first and second edge-adjacent fins also extending from the base in a second direction opposite to the first direction.
0. 49. The light fixture of claim 39, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens.
0. 50. The light fixture of claim 39, wherein the light fixture is configured to operate based on a drive current comprising a current from 700 mA to 1000 mA.
0. 51. The light fixture of claim 39, wherein the cumulative light output comprises a total radiant flux from 30,900 mW to 41,600 mW.
0. 52. The light fixture of claim 39, wherein the cumulative light output comprises a color temperature from 4000° K to 5000° K.
0. 53. The light fixture of claim 39, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens, and wherein the light fixture is configured to operate based on a drive current comprising a current from 700 mA to 1000 mA.
0. 55. The light fixture of claim 54, wherein each of the first and second current control devices comprise: a Bipolar Junction Transistor (BJT); a MOSFET; a junction gate field-effect transistor (JFET); or an insulated gate field effect transistor (IGFET).
0. 56. The light fixture of claim 55, wherein each of the first and second voltage measurement devices comprise: a comparator and an op-amp.
0. 57. The light fixture of claim 54, further comprising a third string of leds connected in series with the first and second string of leds.
0. 58. The light fixture of claim 54, further comprising:
a pulse generator;
an RC circuit coupled to the pulse generator; and
a third current control device coupled to the RC circuit, the third current control device configured to vary the voltage measured by the second voltage measurement device.
0. 59. The light fixture of claim 54, further comprising:
a plurality of heat-sink-mounted led array modules, each module engaging an led-adjacent surface of a heat-sink base for transfer of heat from the module;
a heat-sink heat-dissipating surfaces extending away from the modules;
at least one venting aperture through the heat-sink base to provide air ingress to the heat-dissipating surfaces adjacent to the aperture.
0. 60. The light fixture of claim 54, further comprising:
a housing and an led assembly secured with respect thereto and open to permit air/water-flow over the led assembly, the led assembly comprising:
an led-array;
an extruded heat sink that has a base and heat-transfer surface extending from the base, wherein the heat-transfer surfaces are surfaces of a plurality of fins extending away from the base in a first direction, the fins including first and second fins along the opposite edges of the base, the first and second edge-adjacent fins also extending from the base in a second direction opposite to the first direction.
0. 61. The light fixture of claim 54, wherein, the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens.
0. 62. The light fixture of claim 54, wherein the light fixture is configured to operate based on a drive current comprising a current from 700 mA to 1000 mA.
0. 63. The light fixture of claim 54, wherein the cumulative light output comprises a total radiant flux from 30,900 mW to 41,600 mW.
0. 64. The light fixture of claim 54, wherein the cumulative light output comprises a color temperature from 4000° K to 5000° K.
0. 65. The light fixture of claim 54, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens, and wherein the light fixture is configured to operate based on a drive current comprising a current from 700 mA to 1000 mA.
0. 67. The light fixture of claim 66, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens.
0. 68. The light fixture of claim 66, wherein the drive current comprises from 700 mA to 1000 mA.
0. 69. The light fixture of claim 66, wherein the cumulative light output comprises a total radiant flux from 30,900 mW to 41,600 mW.
0. 70. The light fixture of claim 66, wherein the cumulative light output comprises a color temperature of greater than or equal to 4000° K.
0. 71. The light fixture of claim 66, wherein the cumulative light output comprises a color temperature of greater than or equal to 5000° K.
0. 72. The light fixture of claim 66, wherein the cumulative light output comprises an intensity from 10,000 lumens to 74,468 lumens, and the drive current comprises a current from 700 mA to 1000 mA.
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The present application claims priority to, and is a continuation of U.S. patent application Ser. No. 14/188,184 filed on Feb. 24, 2014,
ILED2=I*R1/(R1+R2)
Where:
One drawback for a current sharing circuit according to this embodiment is that the voltage of the first string of LEDs (VLED1) needs to be no less than the string voltage of the second string of LEDS (VLED2). If this is not the case, then one of the transistors may enter saturation. When in saturation, the transistors may not control the current flowing through each string to the level set by the resistors, i.e., the current flowing through each string of LEDs may be different than the levels determined using the formulas above.
Another embodiment may comprise a third string of LEDs with a transistor connected in series with the third string and a common base with the other two transistors. Such an embodiment may further comprise a third sensing resistor in series with the third string of LEDs. In such an embodiment, the string voltage of the first string of LEDs (the string for which the transistor's base is connected to the collector) needs to be the highest among all the LED string voltages to ensure all the LED currents match the values set by the current sensing resistors.
In the embodiments described above, the constraint of maintaining the voltage drop across the first string of LEDs higher than the voltage drop across the other strings complicates the selection of LEDs. For example, the forward voltage drops of LED strings may vary with temperature and driving current. Thus, in one embodiment, desired operation may be ensured by selecting LEDs such that the minimum voltage of the first string of LEDs is no less than the maximum voltage of the other strings of LEDs. However, in some embodiments, this may increase power loss for the circuit. For example, in one embodiment, in a lighting fixture, if the voltage difference between the voltage of LED1 and the voltage of the other strings is 10V and the driving current is 0.35 A, the power loss will be 3.5 W. This may decrease the overall efficiency of the lighting fixture and also increase the thermal stress to the transistor and LEDs, thus shortening the operational life of the device.
Another embodiment may comprise using linear regulators to regulate the current to all but one of the strings of LEDs. However, such an embodiment may again suffer from the same deficiencies as the circuit described above.
Yet another embodiment for solving the problem discussed above may comprise current balancing transformers to equalize currents flowing through each of the LED strings. In one such embodiment, a magnetic balancer may be used to balance the current flowing through three strings of LEDs. In such an embodiment, two transformers with an equal number of turns of their primary and secondary windings may be connected between the output rectifier and the filter capacitor in three isolated outputs of a switch-mode power supply. Further, in such an embodiment, the current feedback from one output is used to set and regulate the current of the corresponding LED string. The 1:1 turn ratio of the transformer windings maintains the current flowing through each winding of the transformer at substantially the same value provided that the magnetizing current of the transformer is small compared to the winding current.
A deficiency of this embodiment is that it requires a switch-mode power supply. Thus, such an embodiment cannot be used independently, and lacks the flexibility to operate with an arbitrary DC source, for example, a DC current source. Furthermore, the addition of transformers for magnetic balancing into a switch-mode power supply increases the complexity and cost of the circuit. Furthermore, in some embodiments, separate output circuits may be detrimental if a large number of parallel LED strings are required. Furthermore, such an embodiment lacks the capability to individually change or tune the current flowing through each LED string once the turns-ratio of the transformer has been set. Thus, such an embodiment may not be effective for color mixing or control.
Another system for compensating for this problem without the above discussed deficiencies comprises a current control device such as a JFET or MOSFET in series with each string of LEDs. In this, embodiment, each current control device is controlled by a control device, such as a comparator and/or op-amp circuit. Each control device measures the voltage drop before and/or after the current control device, and based on this measurement, varies the impedance of the current control device, e.g., by varying a voltage to the base of the JFET, to increase or decrease the current flowing through each LED string. In some embodiments, the current measurement and control devices may be able to substantially balance the current flowing through each LED string in order to cause each LED string to have substantially the same light output.
Some embodiments may comprise sensing resistors placed in series with each LED string after the control circuit. Choosing resistors with different values may vary the voltage drop measured by each measurement device. Appropriate selection of the value of these sensing resistors enables the designer to vary the brightness of each string of LEDs to provide the desired light output. For example, the designer may comprise multiple strings of white LEDs kept at a substantially high brightness, but further comprise one string of red LEDs to provide a warmer light output. In such an embodiment, the designer may select sensing resistors configured to cause the string of red LEDs to receive a lower current, and therefore be dimmer than the string of white LEDs. In such an embodiment, the brightness of the red LEDs may be set to provide the desired warmth of the total light output.
These illustrative embodiments are mentioned not to limit or define the limits of the present subject matter, but to provide examples to aid understanding thereof. Illustrative embodiments are discussed in the Detailed Description, and further description is provided there. Advantages offered by various embodiments may be further understood by examining this specification and/or by practicing one or more embodiments of the claimed subject matter.
Turning now to the Figures,
As illustrated in
In some embodiments, configurations in which the light sources are in thermal communication with base 20 while power-circuitry unit 40 is in thermal communication with cover 30, may be advantageous. In such embodiments, during operation of the light fixtures this arrangement provides primary heat transfer from the power-circuitry unit and primary heat transfer from the LED emitter(s) to separate major enclosure members, each of which serves as a heat sink.
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In
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In the embodiments shown in
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The embodiments shown in
In the embodiment shown in
The large non-LED-populated area surrounding the LED-populated area provides advantages, such as anisotropic heat conduction during operation. In particular, heat generated by the LED light sources on the LED-populated area spreads in lateral directions across the entire circuit board more than in directions orthogonal to the circuit board into the heat-sink body. That is, the circuit board, which comprises a good thermally-conductive material, such as copper or aluminum, spreads the heat laterally away from the LED-populated area and allows rapid heat transfer to the heat-sink body from across the entire circuit board—even in such “hidden” positions as are beyond the boundary of the optical aperture.
The embodiments shown in
As also schematically shown in
In the embodiment shown in
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The embodiments shown in
The present disclosure provides efficient ways for addressing thermal challenges and extracting increased amounts of light from the LEDs of LED light fixtures. One such way, as described above, is increasing the surface area of the printed circuit board without changing the configuration of the LED array thereon. This takes advantage of the extra circuit-board material for heat-transfer purposes.
In some embodiments, the material used for the LED circuit board should be selected with particular regard to its thermal conductivity. In some embodiments, a simple metal-core circuit board is comprised of a solder mask, a copper circuit layer, a thermally-conducting thin dielectric layer, and a much thicker metal-core base layer. Such layers are laminated and bonded together, providing a path for heat dissipation from the LEDs. In some embodiments, the base layer is by far the thickest layer of the circuit board and may be aluminum, or in some cases copper, a copper alloy or another highly thermally-conductive alloy. A highly-conductive base layer facilitates lateral conduction of heat in the board from beneath the LED-populated area to and across the non-LED-populated area. And since board temperatures remain high even across the non-LED-populated area, the total area of substantial thermal transfer from the circuit board to the heat sink is beneficially large—substantially larger than just the LED-populated area.
In some embodiments, instead of sizing the circuit board to closely match the size of the LED array, the circuit board may be enlarged to have a non-LED-populated area around an LED-populated area such that the non-LED-populated area extends beyond the optical aperture. In one example, such circuit-board enlargement decreases the temperature of the LEDs by 2° C. without adding manufacturing costs allowing for an increase on total lumen output. Larger decrease in temperature and larger increase in total lumen output are possible depending on non-LED-populated area of such a circuit board.
The present disclosure provides a further way for addressing thermal challenges in LED light fixtures. In some embodiments, the thermal load of the driver (power-circuitry unit) is substantially removed from the fixture member (e.g., the base member), which is in primary thermal communication with the LED circuit board. In such an embodiment, the thermal load of the driver may instead be transferred to a separate fixture member such as the light-fixture cover. In one example, such thermal “repositioning” of the driver provides a decrease in the LED temperature of about 2° C. and the thermal separation of the driver from the LED circuit board also lowers the driver temp by 2° C. This permits drive current to be increased while still maintaining a 100,000 hour driver life rating and allowing an increase on total lumen output.
In some examples of light fixtures of this disclosure, enlargement of the non-LED-populated area is combined with separation of the primary thermal paths of the LEDs and the LED driver. In one example, this combination of thermal advantages decreases the LED temperature by 4° C. and allows a 15% increase in the drive current which resulted in 13% increase in total lumen output.
In the embodiments shown in
In the embodiments shown in
The embodiments shown in
In the embodiments shown in
In some embodiments, heat-dissipating surfaces 27 extend substantially orthogonally to front surface 26 of base plate 200. In the embodiments shown in
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In some embodiments, the heat-dissipating surfaces comprise the surfaces of edge-adjacent fins 621 extending transversely from beyond-module portion 681 of heat-sink base 68 at a position beyond venting apertures 69 therealong. As shown in
In the embodiments shown in
In some embodiments, heat-sink base 68 comprises a module-engaging portion 685 between beyond-module portions 681. Heat-sink heat-dissipating surfaces comprise the surfaces of a plurality of middle fins 622 extending transversely from module-engaging portion 685 of heat-sink base 68, as shown in
In the embodiment shown in
In the embodiment shown in
In the embodiments shown in
As shown in
Additional examples of LED-array modules are disclosed in co-pending U.S. patent application Ser. No. 11/774,422,
ILED2=((R1*R3)/Δ)*I
ILED3=((R1*R2)/Δ)*I
Where:
I=the total input current; and
Δ=R1*R2+R2*R3+R1*R3.
One of ordinary skill in the art will recognize that if R1=R2=R3, then ILED1=ILED2=ILED3. Thus, by setting each resistor to an equal value, each LED string may have substantially the same brightness. Alternatively, the resistor values may be varied in order to vary the brightness of each string. In some embodiments, this may be employed for color or lighting compensation. For example, in some embodiments, one or more of the LED strings may comprise different color LEDs, or LEDs with different light output characteristics, e.g., dominant wavelength (“DW”), peak wavelength (“PW”), uniform light output, total luminous flux (“TLF”), and light color rendering index (“CRI”). In some embodiments a designer may select values of resistors R1, R2, and R3 in order to compensate for these differences or provide a higher overall light quality. For example, in one embodiment, one of the LED strings may comprise LEDs of a different color than the other two strings. In such an embodiment, resistors R1, R2, and R3 may be selected such that this different color string has a different current level and thus a different brightness than the other two strings. This may be used to, for example, change the warmth of the light output or control the color of the light.
A person of ordinary skill in the art will recognize that the circuit shown in
Turning now to
In some embodiments, the designer may set the value of resistors R1 and R2 to set a balance between the current through LED strings LED1 and LED2. This will also set the brightness of each of these strings. A designer may set this brightness in order to compensate for color or other factors associated with the LEDs in each string.
Further, in the embodiment shown in
A person of ordinary skill in the art will recognize that the circuit shown in
Turning now to
Each module shown in
Further, in some embodiments, other types of current balancing circuits, such as those described throughout this application may be comprised in a module form. Further, in some embodiments, a plurality of modules such as those shown in
A person of ordinary skill in the art will recognize that the circuit shown in
Turning now to
In the embodiment shown in
In some embodiments, a benefit of using a switching regulator may be lower power loss. In some embodiments, this can improve the overall efficiency of the circuit, and reduce the amount of heat generated by the power loss. In some embodiments, this advantage may still be present even if the voltage difference between LED1 and LED2 is relatively high.
A person of ordinary skill in the art will recognize that the circuit shown in
Turning now to
In the embodiment shown in
In the embodiment shown in
A person of ordinary skill in the art will recognize that the circuit shown in
Turning now to
A person of ordinary skill in the art will recognize that the circuit shown in
There are numerous advantages of the current sharing circuit of present disclosure.
The present disclosure provides efficient ways for addressing thermal challenges and extracting increased amounts of light from the LEDs of LED light fixtures. One such way, as described above, is increasing the surface area of the printed circuit board without changing the configuration of the LED array thereon. This takes advantage of the extra circuit-board material for heat-transfer purposes.
In some embodiments, the disclosed low-profile configuration of the light fixture permits installation against the structure with a relatively small aperture formed in structure surface 1 for electrical connections. This is beneficial in installations for outdoor canopies such as those used at gasoline stations. In particular, the small connection aperture minimizes access of water to the fixture. Another benefit provided by the light fixture according to the present disclosure is that all major components are accessible for servicing from the light-emitting front of the fixture, under the canopy.
Further, some embodiments of the present disclosure provide more flexibility when choosing LED strings. For example, embodiments of the present disclosure enable the designer to select different LEDs with different characteristics. In some embodiments, this enables the designer to comprise different numbers of LEDs in each string.
Further, embodiments of the present disclosure enable additional LED strings to be placed in the same package. Because these LED strings can be placed in parallel, the total voltage drop of the circuit can be reduced. This can allow the designer to build an LED circuit with a greater number of LEDs, and therefore a higher overall light output. Furthermore, as discussed above, an even larger number of LEDs may be incorporated by using a modular approach with a plurality of current sharing drivers of the types discussed above.
Embodiments described above also allow the designer to adjust brightness to create a more pleasing (e.g., warmer light) or to compensate for other factors associated with the each LED, string of LEDs, or module of LEDs. For example, in some embodiments the resistors may be selected to compensate for different light output characteristics, e.g., dominant wavelength (“DW”), peak wavelength (“PW”), uniform light output, total luminous flux (“TLF”), and light color rendering index (“CRI”). In some embodiments, this enables a broader range of LEDs to be used, reducing production cost, because marginal LEDs that would previously have been discarded may be used. Further, the current level can be set to maximize the life of each LED or string of LEDs.
Embodiments of the present disclosure may enable an LED to comprise advantageous light output characteristics. For example, in some embodiments, the cumulative light output of embodiments of the present disclosure may comprise an intensity of greater than or equal to 10,000 lumens. Further, in some embodiments, the cumulative light output may comprise a color temperature of greater than or equal to 4000° K. In some embodiments, the cumulative light output may comprise a Color Rendering Index (“CRI”) of at least 90. In some embodiments, the CRI may be 94 or greater. In some embodiments, the above characteristics may be achieved with a drive current of at least 700 mA. In some embodiments, the drive current may comprise 1,000 mA. In some embodiments, the cumulative light output comprises an intensity of greater than or equal to 13,000 lumens. In some embodiments, the chromaticity comprises within 0.2-0.225 u′ and 0.49-0.51 v′. Further in some embodiments, the total radiant flux is within the range of 30,900-41,600 mW.
Further, embodiments of the present disclosure may enable higher efficiency light, for example, in some embodiments the lumen efficiency may comprise at least 98 lumens per Watt. In some embodiments, the lumen efficiency may comprise at least 105 lumens per Watt.
The table below shows non-limiting example characteristics of LED lighting fixtures according to the embodiments disclosed herein.
Input
LED
Total
Input
current/
1976
1976
General
Color
Intensity/
Radiant
Wattage/
mA
Chromaticity
Chromaticity
CRI/
Temp/
Lm
Flux/
Lm/
W
AC
u′
v′
Mean
° K
Mean
mW
W
93.42
781.7
0.2248
0.5003
93.92
4034
10265.00
30,920.0
109.88
119.66
1000.8
0.209
0.49
90.03
4945
12921.00
40,050.0
107.98
132.9
1112.5
0.2223
0.4978
94.32
4177
13124.00
40,190.0
98.75
132.07
1106
0.2231
0.4976
94.79
4147
13113.00
40,270.0
99.29
134.17
1123.9
0.2242
0.4979
95.01
4101
13512.00
41,590.0
100.71
132.64
1110.6
0.2209
0.4975
94.11
4239
13442.00
41,270.0
101.34
Embodiments of the present disclosure may enable an LED to comprise advantageous light output characteristics. For example, in some embodiments, the cumulative light output of embodiments of the present disclosure may comprise an intensity of at least 10,000 lumens and a lumen efficiency of at least 100 lumens per watt. Further in some embodiments, the cumulative light output may comprise a color temperature of greater than or equal to 4000° K and a Color Rendering Index (“CRI”) of at least 70. In some embodiments, the cumulative light output comprises a color temperature of greater than or equal to 5000° K and a CRI of at least 90. In some embodiments, the drive current comprises at least 1000 mA and the cumulative light output comprises an intensity of greater than or equal to 13,000 lumens. In other embodiments, the cumulative light output comprises an intensity of greater than or equal to 25,000 lumens. In other embodiments, the LED light fixture is configured to operate based on a drive current comprising at least 700 mA and the cumulative light output comprises an intensity of greater than or equal to 20,000 lumens
The table below shows non-limiting example characteristics of LED lighting fixtures according to the embodiments disclosed herein, in which the light temperature comprises at least 4000° K and the Color Rendering Index (“CRI”) comprises at least 70.
Input current/mA AC
Input Wattage/W
LED Intensity/Lm Mean
700
267
24,608
700
533
49,248
1000
421
33,045
1000
831
66,132
700
267
27,276
700
533
54,588
1000
421
36,628
1000
831
73,303
700
267
24,312
700
533
48,654
1000
421
32,647
1000
831
65,336
700
267
26,684
700
533
53,401
1000
421
35,832
1000
831
71,710
The table below shows non-limiting example characteristics of LED lighting fixtures according to the embodiments disclosed herein, in which the light temperature comprises at least 5700° K and the CRI comprises at least 70.
Input current/mA AC
Input Wattage/W
LED Intensity/Lm Mean
700
267
25,555
700
533
51,142
1000
421
34,316
1000
831
68,676
700
267
28,326
700
533
56,687
1000
421
38,037
1000
831
76,123
700
267
25,247
700
533
50,525
1000
421
33,903
1000
831
67,849
700
267
27,710
700
533
55,455
1000
421
37,210
1000
831
74,468
The table below shows non-limiting example characteristics of LED lighting fixtures according to the embodiments disclosed herein, in which the light temperature comprises at least 5000° K and the CRI comprises at least 90.
Input current/mA AC
Input Wattage/W
LED Intensity/Lm Mean
700
267
21,611
700
533
43,250
1000
421
29,021
1000
831
58,079
700
267
19,497
700
533
39,019
1000
421
26,182
1000
831
52,397
700
267
19,262
700
533
38,549
1000
421
25,867
1000
831
51,766
700
267
21,142
700
533
42,310
1000
421
28,390
1000
831
56,816
General Considerations
The methods, systems, and devices discussed above are examples. Various configurations may omit, substitute, or add various procedures or components as appropriate. For instance, in alternative configurations, the methods may be performed in an order different from that described, and/or various stages may be added, omitted, and/or combined. Also, features described with respect to certain configurations may be combined in various other configurations. Different aspects and elements of the configurations may be combined in a similar manner. Also, technology evolves and, thus, many of the elements are examples and do not limit the scope of the disclosure or claims.
Specific details are given in the description to provide a thorough understanding of example configurations (including implementations). However, configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques have been shown without unnecessary detail in order to avoid obscuring the configurations. This description provides example configurations only, and does not limit the scope, applicability, or configurations of the claims. Rather, the preceding description of the configurations will provide those skilled in the art with an enabling description for implementing described techniques. Various changes may be made in the function and arrangement of elements without departing from the spirit or scope of the disclosure.
Having described several example configurations, various modifications, alternative constructions, and equivalents may be used without departing from the spirit of the disclosure. For example, the above elements may be components of a larger system, wherein other rules may take precedence over or otherwise modify the application of the invention. Also, a number of steps may be undertaken before, during, or after the above elements are considered. Accordingly, the above description does not bound the scope of the claims.
The use of “adapted to” or “configured to” herein is meant as open and inclusive language that does not foreclose devices adapted to or configured to perform additional tasks or steps. Additionally, the use of “based on” is meant to be open and inclusive, in that a process, step, calculation, or other action “based on” one or more recited conditions or values may, in practice, be based on additional conditions or values beyond those recited. Headings, lists, and numbering comprised herein are for ease of explanation only and are not meant to be limiting.
Embodiments in accordance with aspects of the present subject matter can be implemented in digital electronic circuitry, in computer hardware, firmware, software, or in combinations of the preceding. In one embodiment, a computer may comprise a processor or processors. The processor comprises or has access to a computer-readable medium, such as a random access memory (RAM) coupled to the processor. The processor executes computer-executable program instructions stored in memory, such as executing one or more computer programs including a sensor sampling routine, selection routines, and other routines to perform the methods described above.
While the present subject matter has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing may readily produce alterations to, variations of, and equivalents to such embodiments. Accordingly, it should be understood that the present disclosure has been presented for purposes of example rather than limitation, and does not preclude inclusion of such modifications, variations and/or additions to the present subject matter as would be readily apparent to one of ordinary skill in the art.
As used herein in referring to portions of the devices of this disclosure, the terms “upward,” “upwardly,” “upper,” “downward,” “downwardly,” “lower,” “upper,” “top,” “bottom” and other like terms assume that the light fixture is in its usual position of use and do not limit the invention to any particular orientation.
In descriptions of this disclosure, including in the claims below, the terms “comprising,” “including” and “having” (each in their various forms) and the term “with” are each to be understood as being open-ended, rather than limiting, terms.
Wilcox, Kurt, Karpichev, Boris, Goelz, David, Miletich, Don, Kinnune, Brian, Hu, Yuequan, Medendorp, Jr., Nicholas William, Ruud, Alan, Ni, Liqin
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