Abstract: Building lights are centrally controlled to reduce power consumption under building central control, or in response to electric utility commands to the building computer. Each lighting wall control unit includes a transceiver which can communicate to at least one neighbor transceiver, thereby forming a distributed communication network extending back to the building computer. The transceivers operate asynchronously with low data rate FSK signals, using carrier frequencies between 900 and 950 MHz. Different communications protocols control packet forwarding and acknowledgement so that messages reach their destination but are not forwarded in endless circles, and so that collisions are minimized.

Abstract: A telephone-based automatic meter reading (AMR) system includes a telemetry device through which a host computer can collect meter readings remotely. So that the telemetry device does not interfere with customer usage of other telephone devices on the telephone line, an apparatus and method is provided which enables the telemetry device to sense both the static off-hook status and the dynamic off-hook status of the telephone line. Numerous circuit components in the telemetry device are shared in sensing both the static and the dynamic off-hook status. Whenever it is determined that a telephone device is, or has become, off-hook, the telemetry device is prevented from using the telephone line. Isolation between the telephone line and the meters is ensured using a transformer and optocouplers.

Abstract: A portable, electronic device for remotely detecting and indicating whether a ballast driving a fluorescent lamp is of the magnetic type. The device comprises a power supply, a light sensor that receives emitted light from the fluorescent lamp and, in response, produces an output signal having a frequency proportional to the flicker frequency of the emitted light, a voltage detector that converts the output signal into a digital signal stream having a pulse frequency proportional to the frequency of the output signal, a microcontroller that determines whether the pulse frequency of the digital signal stream is between predetermined high and low threshold levels, wherein a first indicator signal indicating the presence of a magnetic ballast is produced as an output of the microcontroller when the pulse frequency of the digital signal stream is determined to be between the threshold levels. Until activated by a user, the microcontroller remains in a “sleep” mode, thus conserving the power supply.

Abstract: A telephone-based automatic meter reading (AMR) system includes a telemetry device through which a host computer can collect meter readings remotely. The telemetry device has one or more ports to read one or more meters at pre-scheduled time intervals. All data read from the meter(s) is stored in a non-volatile memory in the device, and the collected data is transferred back to the host computer according to a predetermined schedule (with a call back interval that can be hourly, daily, weekly or monthly). An apparatus and method is provided which enables the host computer to initiate a special data stream to invoke a powerless circuit portion of the telemetry device—specifically, a telephone-side portion which is electrically isolated from the meter-side circuitry (such as by an optocoupler). The ringing signal on the phone line powers the circuitry in this telephone-side portion of the device such that no AC connection or separate battery power is required.

Abstract: A communication method particularly suited for lighting control employs encoding of perturbations in a voltage signal having a fundamental period with a nominal waveform. A control period includes a pre-selected number of fundamental periods of the voltage signal. Different control commands are indicated by imposing a selected perturbation, such as a phase cut, on the nominal waveform with a respective occurrence signature within the control period. The control commands are decoded from the voltage signal by detecting the occurrence signature of the perturbations within each control period. Decoding is accomplished by differentiating the nominal waveform to detect encoded perturbations.

Abstract: An electronic ballast for driving a fluorescent lamp includes an electromagnetic interference (EMI) filter and power circuit, a preconditioner coupled to the EMI filter and power circuit and an inverter circuit coupled to the preconditioner for energizing the fluorescent lamp. The preconditioner includes an active power factor controller and a boost circuit which is controlled at least in part by the active power factor controller. The active power factor controller has a reference voltage input to which is applied a reference voltage. At start up, the inverter provides a time varying signal which is rectified.

Abstract: A lighting control circuit that controls the lighting of particular lamps in response to the toggling of the power switch. The circuit a) connects only with the high (output) side of a lighting system's ballast, b) is completely contained on the high side, and c) with regard to toggling, is dependent upon only a single time period. The circuit can be used with any ballast which makes use of an output transformer and no change need be made to the original ballast circuitry. Users will find operation of the circuit to be straightforward. A triac driven by a flip-flop via a driver transistor is used to control the high frequency AC power that is used to drive the lamps. A Schmitt trigger sharpens the signal generated by the ballast output transformer in response to the toggling of the light switch which is employed to change the output state of the flip-flop. Operationally, all the lamps driven by the ballast are lit when the power switch is initially turned on.

Abstract: A ballast for a gas discharge lamp includes a detection circuit which detects an operating state of the lamp in which the lamp current for the column discharge of one polarity is different from the lamp current for the column discharge of the other polarity by detecting the DC component of the voltage across the discharge lamp. The detection circuit includes (i) a device coupled such that a DC voltage is imposed there across when the lamp current is different for the column discharge according to one polarity verses the other polarity, and (ii) a sensing circuit for sensing the DC voltage across the device. The device may be a capacitive device, and in a particularly inexpensive implementation, is a DC blocking capacitor or a ballast capacitor. The sense circuit senses when the DC voltage across the device exceeds a threshold value, which may corresponds to fully-rectified state of the lamp or more favorably, to a lesser state of imbalance.

Abstract: A ballast includes safety circuitry which senses lamp status through various phases of ballast operation. According to one feature, the ballast is prevented from supplying an output voltage upon initial energization of the ballast when a lamp is not present at the output terminals. The presence of a filament is sensed via a DC path extending through the filament heater windings of an output transformer. When the DC path is not complete, a control input, for example the power supply input of the ballast controller, is not provided with a voltage to start ballast operation. The DC path is also used to restart the ballast if a defective lamp is replaced with a good one. Over-voltage and capacitive mode detection is also disclosed to shut down ballast output upon lamp failure/removal.

Abstract: A programmed electronic ballast circuit including a voltage maintenance circuit to ensure that the integrated circuit continues to oscillate and drive the half-bridge inverter until the DC bus voltage falls to a level insufficient to permit the fluorescent bulbs at the output to ignite. Additionally, the voltage maintenance circuit drives the voltage of the integrated circuit down to a level whereby proper resetting of the integrated circuit and proper preheating of the florescent bulb filaments is assured.

Abstract: Building lights are master controlled to reduce power consumption under building master control, or in response to electric utility commands to the building computer. Each lighting wall control unit includes a transceiver which can communicate to at least one neighbor transceiver, thereby forming a distributed communication network extending back to the building computer. The transceivers operate asynchronously with low data rate FSK signals, using carrier frequencies between 900 and 950 MHz. Different communications protocols control packet forwarding and acknowledgement so that messages reach their destination but are not forwarded in endless circles, and so that collisions are minimized.

Abstract: A lamp controller includes an interface circuit, or receiver, which receives an input signal and decodes control signals supplied from a transmitting device, such as a power line wall controller, according to at least two of the following communication techniques: phase angle control, step control, and coded control. The receiver tests the input signal and identifies which type of control technique is employed by the wall controller connected to the lamp controller. The receiver then decodes the control command from the input signal. In a disclosed embodiment, the lamp controller is gas discharge lamp dimming ballast having a two wire input for connection to the hot dimmed and neutral leads of the power line controller. The ballast has an improved topology in which a pre-conditioner supplies a substantially constant DC voltage to a ballast stage including an inverter, a resonant tank output and a control circuit.

Abstract: A ballast includes safety circuitry which senses lamp status through various phases of ballast operation. According to one feature, the ballast is prevented from supplying an output voltage upon initial energization of the ballast when a lamp is not present at the output terminals. The presence of a filament is sensed via a DC path extending through the filament heater windings of an output transformer. When the DC path is not complete, a control input, for example the power supply input of the ballast controller, is not provided with a voltage to start ballast operation. The DC path is also used to restart the ballast if a defective lamp is replaced with a good one. Over-voltage and capacitive mode detection is also disclosed to shut down ballast output upon lamp failure/removal.

Abstract: A dimming ballast for use with a phase control dimmer, and particularly a triac dimmer, includes an EMI filter selected with a high impedance to avoid excessive voltage and peak currents in the filter due to resonance with the phase controlled AC waveform at low conduction angles, when the load presented by the lamp is low. The EMI filter includes a filter capacitor connected at the output of a rectifier. The ballast also includes circuitry to sense the rectified DC voltage and to discharge the filter capacitor when the rectified voltage is at or near zero, to thereby keep the EMI filter loaded and prevent misfiring of the triac dimmer. In a favorable embodiment, the sensing and discharge function is carried out by a pre-conditioner of the switched-mode type.

Abstract: A gas discharge lamp dimming ballast has a two wire input for connection to the hot dimmed and neutral leads of a phase control dimmer. The ballast has an improved topology in which a pre-conditioner supplies a substantially constant DC voltage to a ballast stage including an inverter, a resonant tank output and a control circuit. A dimming interface circuit derives a dimming signal having a voltage equal to the average value of the rectified output voltage of a full-bridge rectifier feeding the pre-conditioner circuit. The dim signal is independent of the DC rail voltage and, in combination with the maintenance of a substantially constant DC rail voltage, permits of improved dimming control while providing the ease of installation of a two wire ballast. The response time of the interface circuit relative to the pre-conditioner is selected to avoid power imbalances.

Abstract: A system for controlling the intensity of a lamp including a remote sensing device for detecting the presence of an occupant within an area. The device also transmits a signal based on the currently sensed presence of the occupant. After each transmission of an occupancy signal, the device is inhibited from further transmission for a first predetermined period of time to limit power consumption requirements by the battery powered device. The system also includes a light controller responsive to the transmitted occupancy signal for controlling the level of illumination by the lamp. In the absence of a transmitted occupancy signal within a second predetermined period of time, the light controller will instruct the ballast to reduce the level of illumination by the lamp. In the absence of an occupancy signal being transmitted within a third predetermined time period, the light controller will instruct the ballast to turn off the lamp.