WO2006072081A1

WO2006072081A1 - Interruptible hid lighting fixture with color-changing means

Info

Publication number: WO2006072081A1
Application number: PCT/US2005/047621
Authority: WO
Inventors: Roger F. Ii Buelow
Original assignee: Fiberstars Incorporated
Priority date: 2004-12-30
Filing date: 2005-12-30
Publication date: 2006-07-06

Abstract

An interruptible HID lighting fixture is disclosed, which comprises a housing and at least one HID light source within the housing. A ballast circuit is also contained within the housing for starting the at least one HID light source. The housing also contains a DC power supply, which supplies power to the ballast circuit. A control mechanism within the housing ensures that the HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power applied to the fixture. The control mechanism comprises a keep-alive capacitance for supplying the at least one HID lamp with power during the brief interruptions of power. The lighting fixture may include a motor-driven color wheel within the housing whose operation is remotely controlled by a user-operated power switch.

Description

1NTERRUPTIBLE HID LIGHTING FIXTURE WITH COLOR-CHANGING MEANS

This application claims priority from US Provisional Patent Application No. 60/640,486 filed December 30, 2004.

Field of the Invention

The present invention relates to an HID lighting fixture with circuitry operated in response to brief interruptions of power applied to the fixture, typical circuitry consisting of color-changing means. More particularly, the invention relates to the foregoing HID lighting fixture provided with circuitry to ensure that the HID lamp is in the lit state immediately upon the reapplication of power following the brief interruption of power.

Background of the Invention

Submersible, underwater lighting fixtures for pools or other bodies of water often include color-changing means for coloring the light emitted into the body of water. Such lighting fixtures typically employ brief interruptions of power to control the color emissions from the fixture. These fixtures allow the user to momentarily turn power off and on to effect changes in the color output of the fixture. When used with an incandescent lamp or light-emitting diode source, this method of control is simple and effective. However, it would be desirable to use a much more energy efficient, high intensity discharge (HID) arc lighting source instead of an incandescent lamp or light- emitting diode source. But, the use of an HID arc lighting source presents a unique difficulty.

In particular, HID arc lighting sources require several minutes to cool off before they can be relit by a typical ballast. This is because a hot HID arc tube contains relatively high gas pressures that require unusually high voltages to initiate an arc.

This has so far precluded their use in fixtures employing the power-interruption method of control because the several minutes of cool down required before the lamps can be relit is, at best, a distraction to the user, and, at worst, is a hindrance to properly operate the color-changing scheme. Because HID lighting is a more efficient form of lighting, it would be desirable to overcome the foregoing restart time problem. In particular, it would be desirable to provide an HID lighting fixture with circuitry to ensure that the HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power.

Summary of the Invention

In accordance with one form of the invention, an intermptible HID lighting fixture is provided, which comprises a housing and at least one HID light source within the housing. A ballast circuit is also contained within the housing for starting the at least one HID light source. The housing also contains a DC power supply, which supplies power to the ballast circuit. A control mechanism within the housing ensures that the HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power applied to the fixture. The control mechanism comprises a keep- alive capacitance for supplying the at least one HID lamp with power during the brief interruptions of power. The lighting fixture may include a motor-driven color wheel within the housing whose operation is remotely controlled by a user-operated power switch.

The foregoing HID lighting fixture includes circuitry to ensure that the HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power. The claimed lighting design avoids the otherwise lengthy restart interval commonly experienced by HID lighting systems when power is briefly interrupted. This innovation renders practical use of timed interruptions of applied power for remote process control.. An especially preferred remote process concerns controlling the time-changing colored emissions of light from a lighting fixture in such a manner as to be synchronized with the colored emissions of light from one or more other lighting fixtures.

Description of the Drawings

Fig. 1 is a top view of an HID lighting fixture in accordance with the invention, partially in cross section and partially in block.

Fig. 2A shows a graph of power applied over time to the lighting fixture of Fig. 1. Fig. 2B shows a graph corresponding to Fig. 2A of power applied over time to an HID lamp of the lighting fixture of Fig. 1.

Fig. 3 shows an electrical schematic diagram, partially in block, of an HID lighting fixture in accordance with the invention.

Detailed Description of the Invention

This description covers the three topics of (1) typical HID lighting fixtures; (2) general concept of the invention; and (3) a specific embodiment of the invention.

1. Typical HID lighting fixtures Fig. 1 shows an underwater, submersible lighting fixture 10 that includes an HID source 12a. The lighting fixture 10 also contains a housing 14 that is preferably waterproof. HID source 12a and base 12b, together with an integral lamp ballast 16, color wheel motor 18a and its controller 18b, and a preferably dichroic color wheel 20 turned by motor 18a, are contained within housing 14. Housing 14 may include a shell 15a of stainless steel, for instance, and optical material 15b such as glass to allow the light from HID source 12a to reach a body of water (not shown), for instance. Exterior to housing 14 is an AC power source 21 for supplying power to ballast 16 and controller 18b via a user-operated power switch 22, allowing a user to selectively supply power to lighting fixture 10. Ballast 16 is used to ignite an arc (not shown) in HID source 12a. When turned by motor 18a, color wheel 20 changes the predominantly white light of HID source 12a into a sequence of colors of light, which is more pleasing to the eye than merely white light. Color wheel motor 18a and its controller 18b permit either a continuously changing sequence of colors or a single time-static color to be displayed, under the control of a user.

2. General concept of the invention

Without yet referring to electrical schematic diagrams, the present section describes a general concept of the present invention.

The invention teaches a way to circumvent the limitations of the above- described HID relighting procedures, to enable this efficient lighting technology to be employed with the foregoing control scheme. In accordance with the invention, an energy storage device comprising a capacitor, or more generally capacitance, is included in the ballast circuit so as to provide temporary power to the lamp and keep it lit for the brief interval during which the fixture is without power. This interval is typically from about 1 second to about 4 or 5 seconds, for example, 3 seconds. A capacitance used for the foregoing keep-alive function is referred to herein as a keep-alive capacitance. Since low-voltage capacitors — i.e., capacitors rated at below 15 volts — are smaller than their higher voltage counterparts for an equal amount of energy storage, it is advantageous to use the electrical charge stored in a low voltage, 12 volt DC capacitance. A low voltage capacitance may typically be considered a "small form" electrical device, by which is meant that the device does not enlarge the size of the control electronics by more than 50 %. The stored charge in the 12 volt capacitance may be used to power an inverter (not shown) to convert the stored energy into 100 volt AC power, for instance, suitable for powering a typical HID source. For typical HID arc tube parameters of 68 watts, ballast efficiencies of 80 %, and a necessary time-to-live of 3 seconds, the required size of a 12 volt DC capacitor is approximately 1 Farad. Capacitance higher than about 100,000 microfarads is considered high capacitance. The foregoing type of low voltage, high capacitance and small form capacitance is commercially available, and may be used for the purposes of the present invention. Figs. 2A and 2B illustrate typical powering of an HID lamp during a brief power interruption in accordance with the invention. Curve 24 in Fig. 2A, showing power to an overall HID lighting fixture, drops to zero at time 25a and remains at zero until resumption of fixture power at time 25b. Typical durations of power being interrupted between times 25a and 25b are described above, and could be 3 seconds, for instance. Fig. 2B shows power to an HID lamp being kept alive during the power interruption between times 25a and 25b. Curve 26 preferably dips from time 25a to time 25b. In other words, the HID lamp preferably can operate at substantially reduced power of, for instance, 10 percent to 30 percent of nominal power, during the power interruption. This reduces the required energy storage of a capacitance (not shown), referred to herein as a keep-alive, capacitance. However, some HID lamps may not operate if the power supplied to them is substantially reduced. In such a case, curve 26 would have a reduced dip during the power interruption. 3. Specific embodiment

Fig. 3 shows specific embodiment of the present invention, typically comprising a lighting fixture 30 including DC power supply 31 along with a one-way current valve 32 such as a DC blocking diode serially coupled to a keep-alive capacitance 34. The keep-alive capacitance and the one-way current valve are connected across output terminals of the DC power supply. DC power supply 31 may provide an DC output of, for example, 12 volts, and may receive a preferably 120 volt AC input 28 except when interrupted by a user-operated power switch 29 during brief power interruptions, for instance. Keep-alive capacitance 34 is connected across the input of a lamp ballast 16 with an inverter-based design for supplying an AC voltage of, for instance, 40-360 volts to an HID source 12a, which may have a nominal power rating of 68 watts, for instance. HID source 12a may be a type ANSI M110/0 sold by Venture Lighting of Solon, Ohio. Ballast 16 may of the type disclosed in US Patents 5,036,256 and 6,329,762, for instance. Capacitance 34 may comprise a small form, 12 volt, one Farad capacitance, by way of example, for powering HID lamp 12a via ballast 16. One-way current valve 32 prevents power from flowing back into DC power supply 31 when power switch 29 is turned off.

In operation, a user controls power switch 29 to initially turn on HID source 12a, and also to briefly turn off power to lighting fixture 30 when desired for some form of remote process control (e.g., rotational control of a color wheel). During the resulting brief interruptions of power to lighting fixture 30, whose duration might be 3 seconds, the energy stored in keep-alive capacitance 34 keeps HID source 12a alive. Preferably, HID source 12a is kept alive at a power level that is substantially reduced from nominal, as described above in connection with Fig. 2B. As will become apparent from the foregoing description of Fig. 3, the present invention applies to an HID lighting system irrespective of whether a remote process is controlled by brief, timed power interruptions or not. That is, the invention has general applicability to HID lighting systems that do not employ color wheels controlled by brief interruptions of power, or other remote processes. The HID lighting fixtures described above include circuitry to ensure that the

HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power. This innovation renders practical the use of timed interruptions of applied power for remote process control, such as controlling the time-changing colored emissions of light from a lighting fixture.

While the invention has been described with respect to specific embodiments by way of illustration, many modifications and changes will occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true scope and spirit of the invention.

Claims

What is claimed is:

1. lnterruptible HID lighting fixture with color-changing means, the color-changing behavior of which means is controlled by brief interruptions of power initiated by a user, the fixture comprising: a) a housing; b) at least one HID light source within the housing; c) a ballast circuit contained within the housing for starting the at least one HID light source; d) a DC power supply within the housing for supplying power to the ballast circuit; e) a color wheel with a motor and motor controller within the housing; f) a control mechanism within the housing to ensure that the HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power applied to the fixture; and g) the control mechanism comprising a keep-alive capacitance for supplying the at least one HID lamp with power during the brief interruptions of power.

2. The lighting fixture of Claim 1 , wherein the color wheel is a dichroic color wheel.

3. lnterruptible HID lighting fixture, comprising: a) a housing; b) at least one HID light source within the housing; c) a ballast circuit contained within the housing for starting the at least one HID light source; d) a DC power supply within the housing for supplying power to the ballast circuit; and e) a control mechanism within the housing to ensure that the HID lamp is in the lit state immediately upon the reapplication of power following a brief interruption of power applied to the fixture; f) the control mechanism comprising a keep-alive capacitance for supplying the at least one HID lamp with power during the brief interruptions of power.

4. The lighting fixture of any of the preceding claims, wherein: a) the control mechanism further includes a one-way current valve serially coupled to the keep-alive capacitance; b) the serially coupled one-way current valve and keep-alive capacitance are connected across output terminals of the DC power supply; and c) the one-way current valve prevents discharge of the keep-alive capacitance into the DC power supply.

5. The lighting fixture of Claim 4, wherein the serially coupled one-way current valve and keep-alive capacitance are connected across output terminals of the DC power supply.

6. The lighting fixture of any of the preceding claims, wherein substantially all power to run the at least one HID lamp comes from the keep-alive capacitance.

7. The lighting fixture of any of the preceding claims, wherein the keep-alive capacitance supplies power to the at least one HID light source at a substantially reduced power level from a nominal operating level.

8. The lighting fixture of any of the preceding claims, wherein the fixture is designed to operate when the fixture is at least partially submersed in water.

9. The lighting fixture of any of the preceding claims, wherein the keep-alive capacitance is designed for low-voltage, high-capacitance and small form factor.

10. The lighting fixture of any of the preceding claims, wherein each of the brief interruptions of power endures for below about 5 seconds.

11. The lighting fixture of any of the preceding claims, wherein each of the brief interruptions of power endures for below about 4 seconds.