APPARATUS AND METHOD FOR OPERATING A PORTABLE XENON ARC SEARCHLIGHT

• US 20030137834A1
• Filed: 11/15/1999
• Published: 07/24/2003
• Est. Priority Date: 11/15/1999
• Status: Active Grant

• Current Assignee: Xenonics, Inc. (Xenonics Holdings, Inc.)
• Original Assignee: Xenonics, Inc. (Xenonics Holdings, Inc.)
• Inventors: KENNEDY, JEFFREY P., JIGAMIAN, GREGORY Z., PELLING, GEORGE, FORSCHAGER, GORAN, Pelling, Maureen O.
• Granted Patent: US 6,702,452 B2
• Time in Patent Office: Days
• US Class Current: 362/205
• 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 8/003 Searchlights, i.e. outdoor lighting device producing powerful beam of parallel rays, e.g. for military or attraction purposes searchlights mounted on a vehicle B60Q1/245
• CPC Class Codes: F21V 14/02 by movement of light sources in vehicle head lamps F21S41/657
• CPC Class Codes: F21V 14/025 in portable lighting devices
• CPC Class Codes: F21V 14/04 by movement of reflectors in vehicle head lamps F21S41/675
• CPC Class Codes: F21V 14/045 in portable lighting devices
• CPC Class Codes: F21V 19/04 with provision for changing light source, e.g. turret auxiliary devices for cleaning, placing, or removing incandescent lamps H01K3/32, fluorescent lamps H01J9/006
• 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 29/77 with essentially identical diverging planar fins or blades, e.g. with fan-like or star-like cross-section
• CPC Class Codes: F21V 9/20 Dichroic filters, i.e. devices operating on the principle of wave interference to pass specific ranges of wavelengths while cancelling others
• CPC Class Codes: H05B 41/288 with semiconductor devices and specially adapted for lamps without preheating electrodes, e.g. for high-intensity discharge lamps, high-pressure mercury or sodium lamps or low-pressure sodium lamps H05B41/2806 takes precedence
• CPC Class Codes: H05B 41/3928 for high-pressure lamps, e.g. high-intensity discharge lamps, high-pressure mercury or sodium lamps

Abstract

A xenon arc searchlight or illumination system incorporates a high frequency/high efficiency electronic circuit that allows lamp ballasting and charging of the system battery to occur over a wide range of external DC power supplies. The tolerance to variations in the system battery voltage as well as external battery voltage are increased by providing logic control of the converter circuit through a programmed logic device. The intensity of the arc lamp is smoothly decreased or increased in a continuous manner from a maximum intensity to a minimum intensity beam. Ignition of the lamp at its minimum illumination levels is thereby permitted. The xenon arc lamp is uniquely oriented within the searchlight with respect to the reflector to provide the most concentrated and convergent field of illumination on which the lamp is capable, namely with the anode of the lamp turned away from the forward beam direction in the reflector. The resulting light beam is focused by relative movement of a reflector with respect to the lamp by advancing or retracting the reflector along its optical axis of symmetry on which the lamp is also aligned. The searchlight is designed so that the lamp, reflector and battery assemblies are easily field replaceable without tools. The lamp, ballast, battery and charger are provided in a single rugged package which can be sealed for field use. The searchlight is combined by an appropriate mounting adaptable with other optical detector devices such as cameras, binoculars and night vision telescopes. The beam output is similarly usable with a combination of filters to allow the most varied intensity and wavelengths for a particular application, such as smoke filled environments, surveillance employing near-infrared or infrared illumination, ultraviolet, underwater illumination or illumination with any color in the visible range.

Claims

1. An apparatus for producing a high intensity beam of light with high efficiency of conversion of electrical power into light intensity comprising:

a xenon or metal halide arc lamp;

a high frequency/high efficiency electronic ballasting circuit coupled to said arc lamp operating at a frequency substantially greater than 20 kHz;

a battery coupled to said ballasting circuit for powering said ballasting circuit and said arc lamp, said battery having a voltage greater than 12 volts; and

a converter circuit coupled to both said battery, said ballasting circuit and said arc lamp for converting DC voltage from said battery to pulse width modulated switched current to said arc lamp in which said DC voltage is switched by parallel switching transistors.

2. The apparatus of claim 1 wherein said high frequency electronic ballasting circuit coupled to said arc lamp operates at a frequency approximately equal to 100 kHz.

3. The apparatus of claim 1 wherein said battery has a voltage of approximately 22 volts.

4. The apparatus of claim 1 further comprising a printed circuit board on which said ballasting circuit and converter circuit are disposed, said printed circuit board having multiple layers of conductors, high current paths in said ballasting circuit and converter circuit being provided with multiple parallel conductors within said multiple layers so that power losses are minimized.

5. The apparatus of claim 4 wherein said printed circuit board has at least four multiple layers of conductors, and wherein said high current paths are realized with at least four parallel conductors.

6. An apparatus for efficiently producing a high intensity beam of light comprising:

an arc lamp having a plasma in which said light is produced;

a reflector surrounding said lamp, said reflector having a longitudinal optical axis and a focal range from which light is reflected within a predetermined range of collimation of said beam of light, said plasma of said arc lamp being positioned on said optical axis within said focal range;

wherein said reflector is longitudinally displaceable relative to said lamp so that said reflector is moved while maintaining said plasma on said longitudinal optical axis within said focal range.

7. The apparatus of claim 6 further comprising a lamp housing and wherein said arc lamp is fixed within said lamp housing, said reflector being coupled to said lamp housing and longitudinally displaceable with respect to said lamp housing.

8. The apparatus of claim 7 wherein said reflector is threaded to said lamp housing, said reflector being manually rotatable through access outside said apparatus.

9. The apparatus of claim 6 wherein said reflector has a direction of projection of said beam of light and wherein said lamp has an anode and a cathode, said anode being oriented on said longitudinal optical axis relative to said cathode so that said anode is rearwardly positioned in said reflector relative to said cathode and said direction of projection of said beam of light by said reflector.

10. A searchlight comprising:

a lamp;

a lamp circuit coupled to said lamp for powering and controlling illumination produced by said lamp;

a reflector disposed about said lamp to reflect light generated by said lamp, and

a reflector positioned so that said reflector is selectively moved by user with respect to said searchlight while said lamp remains fixed relative to said searchlight.

11. The searchlight of claim 10 wherein said reflector has an optical axis of symmetry, and wherein said lamp is positioned on said optical axis of symmetry, said reflector positioner moving said reflector in two opposing directions along said optical axis of symmetry.

12. The searchlight of claim 11 wherein said reflector positioner retains the relative position of said reflector with respect to said lamp at a last relative position between said lamp and reflector which was selected when last using said searchlight.

13. The searchlight of claim 10 wherein said lamp, reflector positioner are removable from said lamp housing as a unit for field replace without the need of special tools, said searchlight comprising a housing for containing said lamp, lamp circuit, reflector and reflector positioner.

14. The searchlight of claim 10 wherein said reflector has an optical axis of symmetry, wherein said lamp is radially adjustable relative to said reflector to be disposed on said optical axis of symmetry, and wherein radial adjustment of said lamp on said optical axis is field adjustable.

15. An apparatus for producing an adjustable high intensity beam of light comprising:

an xenon or metal halide arc lamp;

a reflector surrounding said lamp, said reflector having a longitudinal optical axis and a focal range on said longitudinal optical axis from which light is reflected within a predetermined range of collimation of said beam of light;

wherein said reflector is longitudinally displaceable relative to said lamp so that said reflector is moved while maintaining arc lamp on said longitudinal optical axis within said focal range.

16. An apparatus for producing a smoothly adjustable high intensity beam of light comprising:

a xenon or metal halide arc lamp;

a high frequency/high efficiency electronic ballasting circuit coupled to said arc lamp;

a power source coupled to said ballasting circuit for powering said ballasting circuit and said arc lamp; and

a converter circuit coupled to both said power source, said ballasting circuit and said arc lamp for converting DC voltage from said power source to pulse width modulated switched current to said arc lamp,

wherein said ballasting circuit is controllable by a switch to vary current supplied to said converter circuit and hence intensity of light output from said arc lamp by a sequence of discrete steps in current and hence in intensity of said lamp which discrete steps in intensity of said lamp are not visually perceptibly different between one step to a next step in said sequence of steps of said current to said lamp.

17. The apparatus of claim 16 comprises a contact switch, a digitally controlled resistance ladder in said ballasting circuit and a programmable logic device coupled to said contact switch and resistance ladder to produce a sequence of digital commands in response to activation of said contact switch to cycle said digitally controlled resistance ladder through said sequence of steps.

18. The apparatus of claim 16 where said sequence of steps begins at a minimum light intensity of said arc lamp and increases to a maximum light intensity of said arc lamp.

19. The apparatus of claim 18 where said sequence of steps after reaching said maximum light intensity of said arc lamp returns to said minimum light intensity of said arc lamp.

20. An apparatus comprising:

an arc lamp;

a high frequency/high efficiency electronic ballasting circuit coupled to said arc lamp, a timing circuit being included in said ballasting circuit;

a DC power source coupled to said ballasting circuit for powering said ballasting circuit and said arc lamp, said power source having a wide range of possible voltage output levels; and

a converter circuit coupled to both said power source, said ballasting circuit and said arc lamp for converting DC voltage from said DC power source to a pulse width modulated switched current to said arc lamp,

wherein said ballasting circuit controls current supplied to said arc lamp by feeding a percentage of said voltage output level from said DC power source to said timing circuit, said timing circuit generating a timing signal at a time which is dependent on said percentage of said voltage output level from said DC power source coupled to said timing circuit, said timing signal coupled to said ballasting circuit to modify said pulse width modulation of said converter circuit and hence current supplied to said arc lamp so as to operate said arc lamp notwithstanding changes in said DC voltage output level of said DC power source.

21. The apparatus of claim 20 where said timing circuit is an RC charging circuit which is charged to a predetermined threshold level by said percentage of said voltage output level from said DC power source and wherein a pulse width of said pulse width modulation is shortened when said predetermined threshold level is reached unless terminated earlier by a predetermined pulsewidth of said pulse width modulation.

22. The apparatus of claim 20 wherein said converter circuit includes an ignition circuit for providing an initial high voltage radio frequency current to said arc lamp to create a glowing plasma within said arc lamp, wherein said ignition circuit controls current supplied to said arc lamp by feeding a percentage of said voltage output level from said DC power source to an ignition timing circuit, said ignition timing circuit generating an ignition timing signal at a time which is dependent on said percentage of said voltage output level from said DC power source coupled to said ignition timing circuit, said ignition timing signal determining pulse width duration of said radio frequency current supplied to said arc lamp so as to reliably ignite said arc lamp notwithstanding changes in said DC voltage output level of said DC power source

23. The apparatus of claim 22 where said ignition timing circuit is an RC charging circuit which is charged to a predetermined threshold level by said percentage of said voltage output level from said DC power source and wherein a pulse width of said radio frequency current is shortened when said predetermined threshold level is reached unless terminated earlier by a predetermined pulsewidth of said radio frequency current.

24. A searchlight comprising:

a portable, compact housing;

a lamp circuit disposed within said housing; and

a quick release optical assembly mechanically coupled to said housing and electrically coupled to said lamp circuit, said quick release optical assembly comprising a xenon or metal halide arc lamp and a reflector, and being removable from said housing and replaceable without requiring rewiring.

25. The searchlight of claim 24 further comprising at least one filter disposable in said quick release optical assembly by means of a screw mount.

26. The searchlight of claim 24 further comprising an integral heat sink formed as part of said housing and thermally coupled to said quick release optical assembly.

27. The searchlight of claim 24 further comprising a tripod mount provided in said housing.

28. The searchlight of claim 24 for use in combination with a second device and further comprising an accessory mounting fixture adapted to permit quick field coupling to said second device so that movement of said housing to direct said lamp is also directs said second device.

29. The searchlight of claim 28 wherein said second device comprises an optical detection system and further comprising a handle formed as part of said housing to allow portability for said searchlight and for mounting to said second device, and wherein said accessory mounting fixture is a thumb screw mount to permit mounting of said optical detection device onto said searchlight and rigidly fixed to said housing.

30. The searchlight of claim 24 wherein said arc lamp has an anode and cathode, said arc lamp being mounted within said searchlight so that said anode of said xenon arc lamp is in the rearward position relative to the direction of a beam projected by said searchlight so that full luminance distribution is placed in the high magnification section of the said parabolic reflector and field illumination of said beam when the arc is placed slightly behind the focal point (spot mode) is slightly convergent and more concentrated in the far-field.

31. The searchlight of claim 24 wherein said arc lamp has an anode and cathode, said arc lamp being mounted within said searchlight so that said anode of said xenon arc lamp is in the rearward position relative to the direction of a beam projected by said searchlight so that full luminance distribution is placed in the high magnification section of the said parabolic reflector and field illumination of said beam when the arc is placed slightly in front of the focal point relative to the direction of the beam (flood mode) is slightly divergent and more uniformly rendered, without the “

black hole”

characteristic of prior art.

32. The searchlight of claim 24 further comprising a field changeable filter disposed on said searchlight to select frequency ranges transmitted in said beam to a selected frequency range depending on application.

33. The searchlight of claim 31 wherein said filter is selected to permit transmission of light in said beam through said filter for illumination in one of the environments comprised of a for illumination in a smoky environment, for infrared illumination, or for underwater illumination.

34. The searchlight of claim 31 wherein said filter is selected for reduction of intensity of said beam from said searchlight to present a minimum intensity output in said beam below which said arc lamp could not operate but for said filter.

35. The searchlight of claim 24 further comprising a recessed external power connector disposed in said housing and electrically coupled to said lamp circuit.

36. The searchlight of claim 24 further comprising an internal, rechargeable battery electrically coupled to said lamp circuit and a battery charging circuit disposed in said housing.

37. The searchlight of claim 24 wherein said housing and quick release optical assembly are coupled to each other so as to be water resistant when coupled.

38. The searchlight of claim 36 wherein said quick release optical assembly has a face plate disposed over said reflector and wherein said face plate is sealed to said quick release optical assembly by means of a watertight gasket.

39. The searchlight of claim 24 wherein said quick release optical assembly further comprises a quick release lamp housing, said arc lamp being disposed in said lamp housing and adjustably alignable with respect to said reflector even after said quick release optical assembly is coupled to said housing, said quick release lamp housing having being removable from said quick release optical assembly and replaceable without requiring realignment with respect to said reflector in order to be optimally positioned within said reflector.

41. The apparatus of claim 39 further comprising a housing in which said battery is included with said battery, converter circuit, ballasting circuit and arc lamp as a single compact unit.

42. The apparatus of claim 39 wherein said ballasting circuit comprises a lamp current circuit having output coupled across said arc lamp for providing a converted dc current and voltage to said arc lamp;

and an igniter coupled across said arc lamp to provide a high voltage RF ignition current to said arc lamp wherein said lamp current circuit is controlled by a smooth variation of current to said arc lamp to correspondingly smoothly vary light output from said arc lamp between high and low intensities by visually imperceptible amounts.

43. The apparatus of claim 41 wherein said lamp current circuit is controlled to provide said smooth variations between high and low intensities by a multiplicity of small digital current steps.

44. The apparatus of claim 41 wherein said lamp current circuit is controlled to provide said smooth variations between high and low intensities by an approximate analog variation in current intensity provided to said arc lamp.

45. The apparatus of claim 39 wherein said ballasting circuit is controlled by a control circuit to turn said arc lamp on at minimum intensity levels of operation.

40. An apparatus for generating a beam of light comprising:

an arc lamp;

a high frequency/high efficiency electronic ballasting circuit coupled to said arc lamp;

a battery coupled to said ballasting circuit for powering said ballasting circuit and said arc lamp; and

a converter circuit coupled to both said battery and said arc lamp for providing both power to said arc lamp and for recharging said battery from an external power source.