Solid state continuous sealed clean room light fixture

• US 6,871,983 B2
• Filed: 10/25/2001
• Issued: 03/29/2005
• Est. Priority Date: 10/25/2001
• Status: Expired due to Fees

• Current Assignee: Koninklijke Philips N.V.
• Original Assignee: TIR Systems Limited (Koninklijke Philips N.V.)
• Inventors: Jacob, Stephane Frederick, York, Allan Brent
• Primary Examiner(s): O'Shea, Sandra
• Assistant Examiner(s): Zeade, Bertrand
• Application Number:
  US10/035,477
• Publication Number:
  US 20030081419A1
• Time in Patent Office: 1,251 Days
• Field of Search: 362/364, 362/373, 362/574, 362/800, 362/404, 362/545, 362/294, 362/293, 362/33, 362/809, 362147-148, 362/150, 362/241, 362/245, 362/247, 362/455, 362/459, 362/575
• US Class Current: 362/364
• CPC Class Codes: F21S 8/04 intended only for mounting on a ceiling or the like overhead structures F21S8/02 takes precedence; details of ceiling bases F21V21/03
• CPC Class Codes: F21V 13/04 the elements being reflectors and refractors for vehicle rear lights F21S43/40
• CPC Class Codes: F21V 21/025 Elongated bases having a U-shaped cross section
• CPC Class Codes: F21V 21/04 Recessed bases
• CPC Class Codes: F21V 21/096 Magnetic devices
• CPC Class Codes: F21V 23/002 Arrangements of cables or conductors inside a lighting device, e.g. means for guiding along parts of the housing or in a pivoting arm
• CPC Class Codes: F21V 27/00 Cable-stowing arrangements structurally associated with lighting devices, e.g. reels storing lengths of cable in general B65H; the lighting devices being vehicle headlamps F21S41/192; the lighting devices being vehicle lights F21S43/195
• CPC Class Codes: F21V 29/70 characterised by passive heat-dissipating elements, e.g. heat-sinks
• CPC Class Codes: F21V 29/74 with fins or blades
• 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 29/85 characterised by the material liquid coolants F21V29/56
• CPC Class Codes: F21V 29/89 Metals
• CPC Class Codes: F21V 31/00 Gas-tight or water-tight arrangements
• CPC Class Codes: F21V 5/002 using microoptical elements for redirecting or diffusing light
• CPC Class Codes: F21V 7/06 with parabolic curvature
• CPC Class Codes: F21V 7/24 characterised by the material
• CPC Class Codes: F21V 7/28 characterised by coatings
• CPC Class Codes: F21W 2131/40 Lighting for industrial, commercial, recreational or military use
• CPC Class Codes: F21Y 2115/10 Light-emitting diodes [LED]
• CPC Class Codes: Y10S 362/80 : Light emitting diode

Abstract

A clean room ceiling light fixture formed as a sealed housing with a downwardly-directed light emitting aperture. A heat sink fixed within and spaced from the housing defines a cable raceway inside the housing. A plurality of LEDs are mounted on the heat sink. A high refractive index (polycarbonate) reflector coupled to each LED efficiently directs the LED'"'"'s light through the aperture into the clean room. The LEDs and/or reflectors can be anti-reflectively coated to improve light transmission efficiency. A refractive index matching compound applied between each LED-reflector pair further improves light transmission efficiency. A spectrally selective filter material prevents ultraviolet illumination of clean rooms used for lithographic processes which are compromised by ultraviolet rays. A holographic diffusion lens and/or variable transmissivity filter can be provided to uniformly distribute the LEDs'"'"' light through the aperture. The fixture can be sized and shaped for snap-fit engagement within the H-Bar type clean room ceiling.

Claims

1. A light fixture for a clean room ceiling formed by a plurality of frame members arranged in an H-Bar configuration, the light fixture comprising:

(a) a sealed housing module sized and shaped for removably replaceable engagement within the ceiling frame members, the module having a downwardly-directed light emitting aperture;

(b) a heat sink fixed within the module and spaced from an internal wall of the module to define a cable raceway between the heat sink and the internal wall;

(c) a plurality of light-emitting diodes mounted within the module on the heat sink, each one of the light-emitting diodes having a lens for directing light emitted by the one of the light-emitting diodes through the aperture into the clean room; and

,

(d) a power supply for applying drive current to the light-emitting diodes.

2. A light fixture as defined in claim 1, each one of the light-emitting diodes further having a reflector for directing light emitted by the one of the light-emitting diodes through the aperture into the clean room.

3. A light fixture as defined in claim 1, further comprising an anti-reflective coating on each one of the lenses.

4. A light fixture as defined in claim 2, further comprising an anti-reflective coating on each one of the reflectors.

5. A light fixture as defined in claim 2, wherein the reflectors are formed of a high refractive index material.

6. A light fixture as defined in claim 5, wherein the high refractive index material is polycarbonate.

7. A light fixture as defined in claim 2, further comprising, for each one of the lenses and an adjacent one of the reflectors, a refractive index matching compound applied between the one of the lenses and the adjacent one of the reflectors.

8. A light fixture as defined in claim 7, wherein the refractive index matching compound is an elastomer.

9. A light fixture as defined in claim 2, wherein the reflectors are formed of a spectrally selective filter material.

10. A light fixture as defined in claim 9, wherein the spectrally selective filter material is a deep dyed polyester.

11. A light fixture as defined in claim 9, wherein the spectrally selective filter material is a spectrally selective thin film filter material.

12. A light fixture as defined in claim 1, further comprising, a holographic diffusion lens for uniformly distributing, through the aperture, the light emitted by the light-emitting diodes.

13. A light fixture as defined in claim 12, wherein the holographic diffusion lens further comprises a structured surface prismatic film.

14. A light fixture as defined in claim 1, further comprising;

a variable transmissivity filter for uniformly distributing, through the aperture, the light emitted by the light-emitting diodes.

15. A light fixture as defined in claim 1, wherein the module is removably magnetically attachable to the ceiling frame members.

16. A light fixture as defined in claim 1, wherein the module is removably adhesively attachable to the ceiling frame members.

17. A light fixture as defined in claim 1, wherein the power supply further comprises an uninterruptible power supply.

18. A light fixture as defined in claim 1, wherein the power supply further comprises an in-line DC-DC converter coupled between a high voltage DC power supply and the fixture.

19. A light fixture as defined in claim 17, wherein the power supply further comprises an in-line DC-DC converter coupled between the uninterruptible power supply and the fixture.

20. A light fixture as defined in claim 17, wherein the uninterruptible power supply is located at a remote location from the fixture.

21. A light fixture as defined in claim 19, wherein the uninterruptible power supply is located at a remote location from the fixture.

22. A light fixture as defined in claim 18, wherein the DC-DC in-line converter is located closely proximate to the fixture.

23. A light fixture as defined in claim 19, wherein the DC-DC in-line converter is located closely proximate to the fixture.

24. A light fixture as defined in claim 21, wherein the DC-DC in-line converter is located closely proximate to the fixture.

25. A light fixture as defined in claim 1, wherein the power supply further comprises a regulator for regulating the drive current as a function of time.

26. A light fixture as defined in claim 25, further comprising a light sensor located in the clean room and electrically connected to the regulator, the light sensor producing an output signal representative of light intensity near the light sensor, and wherein the regulator further regulates the drive current as a function of the output signal.

27. A light fixture as defined in claim 25, further comprising a light sensor located in the clean room and electrically connected to the regulator, the light sensor producing an output signal having a magnitude representative of light intensity near the light sensor, and wherein the regulator further regulates the drive current in inverse proportion to the output signal magnitude.

28. A light fixture as defined in claim 1, further comprising a programmable controller electrically connected between the power supply and the light-emitting diodes, the programmable controller for programmatically regulating the drive current as a function of time.

29. A light fixture as defined in claim 1, further comprising a programmable controller electrically connected between the power supply and the light-emitting diodes, the programmable controller for programmatically regulating the drive current as a function of time to maintain substantially constant light flux output of the light-emitting diodes.