Electric lamp and discharge devices: systems – Current and/or voltage regulation
Reexamination Certificate
1999-03-11
2001-05-01
Philogene, Haissa (Department: 2821)
Electric lamp and discharge devices: systems
Current and/or voltage regulation
C315S308000, C315S339000, C315S362000, C315SDIG004
Reexamination Certificate
active
06225759
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to lighting control circuitry, and in particular to a dimmer for use with gas discharge lamp ballasts and incandescent lamps.
BACKGROUND OF THE INVENTION
Dimming circuits for incandescent lamps are well-known and extensively used. However, there are fewer commercially available dimming circuits suitable for use with gas discharge lamps, such as fluorescent lamps. Available gas-discharge lamp dimming circuits contain complex circuitry and a high number of components which makes them expensive to build, install and retrofit to existing ballasts. Consequently, most residential and commercial fluorescent installations do not have dimming capability.
Dimming of fluorescent and other gas discharge lamps is commonly accomplished by a digital dimming circuit located in the ballast and controlled using the “0 to 10V” signalling protocol. This protocol uses a pair of dedicated wires to send a dimming control signal represented by a voltage signal of value between 0 and 10 volts to the ballast dimming circuitry. The ballast dimming circuitry then converts this control signal into a signal adapted to change ballast operating conditions. While this dimming method is popular for dimming fluorescent and other gas discharge lamps, it suffers from several significant disadvantages.
In order to provide dimming for existing lighting installations, the dedicated wires of this signalling system must be installed within ceilings and walls, resulting in significant installation costs. Further, since each ballast requires a separate set of wires, the lighting system is complex to wire and can pose a safety threat if any of the wires are improperly installed (i.e., if the dimming signal wires are mistakenly connected to the main power source, the ballast will short, severely damaging the device and possibly injuring the installer).
Further, signal wires from one ballast must be galvanically isolated from possible interference and noise produced by other ballast signal wires. Such isolation may require the use of additional components which significantly adds to the expense and complexity of a lighting system comprising a number of ballasts. Moreover, since the main power wires are often in close proximity to the signal wires, control signals are still often affected by electrical interference and noise. Corrupted control signals consequently can cause device malfunctions.
A dimming protocol which offers independent fixture addressing is a digital protocol method developed by Tridonic Corporation. This protocol uses signal wires to transmit digital information representing the desired brightness level (i.e., 128 or 256 levels of brightness) and other information such as the particular address of the target ballast to be dimmed. While this method allows for increased unit flexibility and better signal wire economy, the system still requires the use of complex decoders within each ballast and stand alone dimming ballasts which are typically twice as expensive as the existing 0-10 Volt protocol dimming ballasts. In addition, the digital signal sent to the ballasts is susceptible to electrical noise and interference.
Another dimming signalling system is shown in U.S. Pat. No. 4,181,873 to Nuver. U.S. Pat. No. 4,181,873 avoids the need for a separate set of signal leads to a lamp ballast by encoding a high frequency signal (200 kHz to 400 kHz) on an AC line voltage. This signal provides control information which is used to control the gating to a triac for dimming a lamp. However, this dimming protocol is rarely used because such RF communications are very sensitive to the electrical noise commonly found on an AC line. Further, this signalling protocol generates what is known as “RF pollution” which affects radio frequency transmissions and which violates FCC Regulations regarding the maximum level of radio frequency interference that any industrial or commercial electrical device may produce.
Finally, a power line control system is disclosed in U.S. Pat. No. 5,614,811 to Sagalovich. U.S. Pat. No. 5,614,811 discloses encoding voltage pulses within an AC power line voltage at zero crossing points of any one-half AC cycle. The voltage pulses act as control signals for any electrical device which is connected to the AC power line through a receiver/control apparatus. While this control system alleviates some disadvantages associated with RF pollution, the system utilizes relatively complex transmitter and receiver circuits and still creates some RF pollution. Further, this control system cannot be implemented within a European power system as it requires electrical connection to both hot and neutral wires. In Europe, the neutral wire of the AC line is typically provided directly to the lamp or device and is not available for connection to an intermediate control device.
Thus, there is a need for a dimmer circuit for gas discharge lamp ballasts and incandescent or halogen lamps, which can be implemented in a cost-effective manner and which facilitates easy and safe installation, which is not susceptible to electrical interference or corruption, which meets established FCC radio interference noise regulations, which can be easily retrofitted to operate within any dimming ballast, and which can be used in association with European power systems.
BRIEF SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a dimmer circuit for controlling an electrical lighting device having a load input, said dimmer circuit including:
(a) a power input terminal coupled to a first wire of an AC power line, said AC power line generating an input AC waveform across said first wire and a second wire, said input AC waveform having a selected waveform energy,
(b) an encoding circuit coupled to said input terminal for selectively wave chopping the half cycles of said input AC waveform in the vicinity of the zero crossings of input AC waveform to generate a plurality of output waveforms across an output terminal and said second wire, said output waveforms including said input AC waveform having at least some half cycle zero crossing step delays, each output waveform having a waveform energy substantially the same as said selected waveform energy,
(c) a controller coupled to said encoding circuit and operative to cause said encoding circuit to produce across said output terminal and said second wire a selected one of said output waveforms,
(d) said load input being adapted to be coupled to said output terminal and to said second wire for receiving said selected output waveform so that said selected output waveform provides operational power to said electrical lighting device, and
(e) a decoder adapted to be coupled to said output terminal and to said second wire and to said electrical lighting device and responsive to the selected output waveform from said encoding circuit for controlling said electrical lighting device.
In a second aspect, the present invention provides a method of controlling an electrical lighting device at a first location connected to an AC power line at a second location, said AC power line having first and second wires and providing an AC waveform across said first and second wires, said AC waveform having a selected waveform energy, said method including the steps of:
(a) selectively wave chopping the half cycles of said input AC waveform in the vicinity of the zero crossings of input AC waveform, to generate a plurality of output waveforms across an output terminal and said second wire, said output waveforms including said AC waveform having at least some half cycle zero crossing step delays,
(b) selectively transmitting one of said output waveforms from said second location across said first and second wires to said electrical load, to provide operational power to said load,
(c) decoding said power waveforms at said first location, and controlling said electrical lighting device in accordance therewith.
Further objects and advantages of the invention will appear from the following description, taken together with the
Bogdan Alexei
Hoffknecht Marc Oliver
Bereskin & Parr
Lumion Corporation
Philogene Haissa
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