LED work light

• US 7,553,051 B2
• Filed: 03/18/2005
• Issued: 06/30/2009
• Est. Priority Date: 03/18/2004
• Status: Active Grant

• Current Assignee: Alltemp Products Company Limited (DiversiTech Holdings, Inc.)
• Original Assignee: Brasscorp Limited
• Inventors: Dobbin, Sarah, Brass, Jack, Hallgrimsson, Bjarki, Hilts, Lorne, Klipstein, Donald L., Whitfield, Robert Tod
• Primary Examiner(s): Payne; Sharon E
• Application Number:
  US11/083,086
• Publication Number:
  US 20050265035A1
• Time in Patent Office: 1,565 Days
• Field of Search: 362/373, 362/185, 362/186, 362/190, 362/237, 362/244, 362/311, 362/336, 362/337, 362/340, 362/451, 359726-728
• US Class Current: 362/373
• CPC Class Codes: F21L 14/023 having two or more, or different light sources
• CPC Class Codes: F21L 4/00 Electric lighting devices with self-contained electric batteries or cells
• CPC Class Codes: F21L 4/08 characterised by means for in situ recharging of the batteries or cells
• CPC Class Codes: F21S 4/20 with light sources held by or within elongate supports
• CPC Class Codes: F21S 45/47 Passive cooling, e.g. using fins, thermal conductive elements or openings
• CPC Class Codes: F21V 15/04 Resilient mountings, e.g. shock absorbers shock absorbing devices of vehicle headlamp housings B60Q1/0491; in general F16F15/04
• CPC Class Codes: F21V 17/12 by screwing
• CPC Class Codes: F21V 21/06 Bases for movable standing lamps; Fixing standards to the bases F21V21/08 takes precedence
• CPC Class Codes: F21V 21/08 Devices for easy attachment to any desired place, e.g. clip, clamp, magnet
• CPC Class Codes: F21V 21/32 Flexible tubes
• CPC Class Codes: F21V 21/406 for portable lighting devices
• CPC Class Codes: F21V 23/02 the elements being transformers, impedances or power supply units, e.g. a transformer with a rectifier
• CPC Class Codes: F21V 23/0435 activated by remote control means
• CPC Class Codes: F21V 27/005 for portable lighting devices
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/75 with fins or blades having different shapes, thicknesses or spacing
• CPC Class Codes: F21V 29/763 the planes containing the fins or blades having the direction of the light emitting axis
• CPC Class Codes: F21V 29/83 the elements having apertures, ducts or channels, e.g. heat radiation holes
• CPC Class Codes: F21V 5/04 of lens shape
• CPC Class Codes: F21V 7/0091 using total internal reflection
• CPC Class Codes: F21Y 2103/10 : comprising a linear array of point-like light-generating elements
• CPC Class Codes: F21Y 2115/10 : Light-emitting diodes [LED]
• CPC Class Codes: H05B 45/10 : Controlling the intensity of the light
• CPC Class Codes: H05B 45/375 : using buck topology
• CPC Class Codes: H05B 45/38 : using boost topology
• CPC Class Codes: H05B 45/56 : involving measures to prevent abnormal temperature of the LEDs
• CPC Class Codes: Y02B 20/30 : Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

Work light has LEDs that require heatsink. Desired radiation pattern achieved by using optical components designed to produce beam or LEDs may have beams in different directions. Radiation pattern of LEDs may be changed by refractive-reflective optics or by convex lenses. Convex lenses may be hemispheres, other planoconvex shapes, concavo-convex shapes, or other shapes. Curved surfaces on any lenses may be spherical or aspheric. Ballast to operate the LEDs from line voltage AC or low voltage DC. Work light may contain batteries. The work light may be mounted on a stand. May have accessory mount. May have charging station. May have a paging transmitter to activate a paging receiver in work light. May have openings for heat transfer from heatsink to ambient air external to light.

Claims

1. A work light comprising:

a) a high power LED that normally requires a heatsink for operation in a normal working environment while preserving a useful life in prolonged use,

b) a heatsink thermally connected to the LED to preserve useful working life of the LED when operated in prolonged use,

c) a casing substantially enclosing the LED and the heatsink, the casing comprising at least a portion that is transparent through which light can emit from the casing about a beam axis,

d) an optic within the casing associated with the LED such that a beam of light radiating from the LED has a beam width that is changed by the optic, and light emitting from the optic emits a useful beam of light through a transparent portion of the casing, the useful beam of light with a width adequate for use in working for prolonged periods that is essentially at least 40 degrees and essentially no more than 90 degrees,

wherein the casing is substantially tubular and wherein the beam emitted from the casing has a central beam axis that is essentially perpendicular to a longitudinal axis of the casing, and wherein the beam of light emitting from the optic has a more uniform light density across its beam width than the light density across a beam emitted by the LED, and

wherein the optic is a convex lens, the convex lens has both a convex surface and a concave surface, and the concave surface is curved more sharply towards its edge than towards its center such that light is more evenly spread across the area of the beam when the LED associated with the concave surface has a beam width greater than 90 degrees.

2. The work light of claim 1 wherein the concave surface is flat in its center.

3. The work light of claim 1 wherein:

the LEDs are white LEDs.

4. The work light of claim 3 further comprising:

a) a plurality of LEDs including the LED,

b) a plurality of optics including the optic, and

c) at least one heatsink including the heatsink,

wherein each optic is associated with a respective one of the LEDs, and each LED is thermally connected to the at least one heatsink, and

wherein each LED produces a beam of light having a beam width other than essentially at least 40 degrees and essentially no more than 90 degrees,

wherein the plurality of LEDs and optics are arranged to produce a combined work light beam having a beam width that is essentially at least 40 degrees and essentially no more than 90 degrees,

wherein the beam of light emitting from each optic has a more uniform light density across its beam width than the light density across a beam emitted by its associated LED, and

wherein each LED of the plurality of LEDs produces a beam of light having a beam width of essentially less than 40 degrees and each optic is placed forward from its respective LED in order for said work light to produce a work light beam width that is essentially more than 40 degrees and essentially no more than 90 degrees, and

wherein each optic is a convex lens, each convex lens has both a convex surface and a concave surface, and the concave surface is curved more sharply towards its edge than towards its center such that light is more evenly spread across the area of the beam when the LED associated with the concave surface has a beam width greater than 90 degrees.

5. The work light of claim 4 wherein:

said work light works from low voltage direct current.

6. The work light of claim 5 further comprising:

a DC power source within the casing.

7. The work light of claim 5 wherein:

the DC power source comprises rechargeable batteries.

8. The work light of claim 7 wherein:

the casing is plastic.

9. The work light of claim 8 further comprising:

a handle covering about a handle portion of the casing extending from a head portion of the casing, wherein the head portion houses the LED and heatsink.

10. The work light of claim 9 wherein:

the handle covering comprises a compressible material.

11. The work light of claim 10 wherein:

the compressible material is selected from rubber or a thermoplastic elastomer.

12. The work light of claim 4 wherein:

at least one convex lens is part of a transparent lens assembly.

13. The work light of claim 12 wherein:

the transparent lens assembly is molded.

14. The work light of claim 13 wherein:

the lens assembly is machined after molding.

15. The work light of claim 14 wherein:

the lens assembly is polished after machining.

16. The work light of claim 4 wherein the convex surface of each convex lens has a diameter, and the concave surface of each convex lens has a diameter smaller than that of the convex surface of its respective convex lens.

17. The work light of claim 4 wherein the concave surface of each convex lens is flat in its center.

18. The work light of claim 4 wherein:

the plurality of LEDs are mounted substantially on one plane to emit light substantially perpendicular to the plane.

19. The work light of claim 18 wherein:

the plurality of LEDs are mounted substantially along a line in the plane.

20. The work light of claim 4 wherein:

dissipation of heat from the at least one heatsink maintains the temperature of an outside surface of the LEDs below about 75 degrees Celsius in a range of ambient temperatures below about 35 degrees Celsius.

21. The work light of claim 20 wherein the at least one heatsink is set back from an adjacent internal surface of the casing.

22. The work light of claim 20 further comprising:

an air gap between the at least one heatsink and the adjacent internal surface of the casing.

23. The work light of claim 20 wherein each LED emits light about a central beam axis,

wherein the at least one heatsink has three dimensions:

depth, width and height,

wherein each LED is mounted adjacent and in thermal contact with the at least one heatsink along the respective LED central beam axis in an opposite direction to which the LED emits light,

wherein the depth of the at least one heatsink is measured along the respective LED central beam axis,

wherein the width and height of the at least one heatsink are measured perpendicular to the depth and to one another, and

wherein the depth of the at least one heatsink is substantially less than the width of the at least one heatsink and substantially less than the height of the at least one heatsink, such that the work light uses less space in the direction in which light is desired.

24. The work light of claim 4, wherein each LED has a nominally lambertian radiation pattern.