Abstract: Methods and apparatus for controlling the brightness level of a lamp in a backlit LCD display include primary and secondary controllers. The primary controller establishes the arc drive to the lamp to achieve the desired lamp brightness. The primary controller includes a desired brightness set-point as a first input, and a feedback signal corresponding to actual brightness detected at the lamp as a second input. The primary controller operates in real time, essentially adjusting the lamp arc drive instantaneously as a function of the detected brightness feedback signal. The secondary controller is employed to fine tune the control of the lamp by determining whether the desired brightness level may be achieved more efficiently. The secondary controller varies one or more parameters, such as temperature, within the lamp to achieve the optimum operating point of the lamp at the desired brightness level.

Abstract: An illumination control apparatus for controlling illumination by detecting a change in an environment is provided. The illumination control apparatus includes a magnetic field detector for detecting a change in a magnetic field generated by a magnetized ferroelectric object to output a first signal having a voltage which is proportional to the change in the magnetic field; an amplifier for amplifying the first signal; a discriminator for discriminating a level of the amplified voltage to output an illumination on-signal having a first logic level if the level of the amplified voltage is higher than a predetermined voltage, and otherwise to output an illumination off-signal having a second logic level; an illumination controller for outputting an illumination driving voltage in response to the illumination on-signal having the first logic level; and an illumination portion for producing light in response to the illumination driving voltage.

Abstract: In a flash apparatus capable of making high-speed repeating light emission, a self-maintaining switch element provided for various purposes is prevented from erroneously operating due to the high-speed repeating light emission, by providing a circuit element which reverse-biases a control electrode of the self-maintaining switch element.

Abstract: A drive circuit of a light emitting element capable of setting a desired constant current and capable of operating stably at a high speed while holding a forward direction voltage required for the emission of light even under a low power supply voltage, wherein there is provided an input circuit which receives differential drive signals and outputs differential signals of levels in accordance with the level of a supplied drive voltage, a differential output circuit in which an emitter-connection portion of transistors is grounded via a resistor, the differential signals and are supplied to bases, and a laser diode is connected to a collector of the transistor, a reference voltage generation circuit which generates a reference voltage, a comparison circuit which compares the voltage of the emitter-connection portion with the reference voltage and outputs a signal of the level in accordance with the result of comparison, and a variable voltage supply circuit which generates a voltage in accordance with the inpu

Abstract: An electronic ballast (EVG) is provided for operating at least one lamp (10), wherein a light sensor (20) for monitoring the brightness of a specific physical area (28) can be connected to the electronic ballast. A control arrangement (12) controls or regulates the brightness of the lamp (10) as a function of an actual brightness value delivered by the light sensor (20) and when the electronic ballast is put into operation automatically identifies whether a light sensor (20) is connected to the connection arrangement (18a, 18b).

Abstract: A fill-in light emitting apparatus having an illuminating mechanism for emitting illumination light whose color temperature can be varied; a color temperature metering mechanism for measuring the color temperature of the external light; and a color temperature controlling mechanism for varying the color temperature of the illumination light in accordance with color temperature data measured by the color temperature metering mechanism.

Abstract: A fill-in light emitting apparatus having an illuminating mechanism for emitting illumination light whose color temperature can be varied; a color temperature metering mechanism for measuring the color temperature of the external light; and a color temperature controlling mechanism for varying the color temperature of the illumination light in accordance with color temperature data measured by the color temperature metering mechanism.

Abstract: A luminaire diagnostic system including a lamp and a photocontroller for automatically turning the lamp on during periods of darkness and off during periods of daylight wherein the photocontroller includes detector circuitry for detecting the load drawn by the lamp, a microprocessor, responsive to detected load and programmed to predict a condition of the lamp such as a cycling event and/or lamp out condition based on the load drawn by the lamp, and an indicator such as a visual alarm for indicating the occurrence of the condition detected and/or a transmitter for transmitting the detected condition to a remote location. Also, upon cycle detection, the lamp may be turned off to prevent damage to fixture components.

Abstract: A video lighthead mountable to a video camera and having a dimmer control that varies the intensity of the light output from the lighthead using pulse width modulation techniques. A photo sensor measures the intensity of light reflected from a subject in front of the lighthead. The intensity of light output from the lighthead is adjusted by control circuitry in response to changes in measured reflected light intensity to maintain a constant level of illumination. The adjustment is carried out by modifying the duty cycle of a pulse width modulation circuit. The duty cycle adjustment of the pulse width modulation is also used to compensate for supply voltage variations in order to maintain constant light output.

Abstract: A light level sensor for use in controlling the switching of artificial lighting. The sensor comprises a photoelectric transducer which provides an output signal at a level which is significant of the illumination level of incident light. An A-D converter and a microprocessor are located in circuit with the transducer for detecting the level of the transducer output signal and for any cyclic variation of the transducer output signal resulting from cyclic variation of the level of incident light. Further circuit means are provided for generating a sensor output signal if either (a) the level of the transducer output signal is below a predetermined level or (b) the level of the output signal is above the predetermined level and, at the same time, cyclic variations occur in the level of the transducer output signal.

Abstract: A method and circuit for detecting arc instabilities in a high pressure gas discharge lamp. The method and circuit rectify and low pass filter the lamp voltage to obtain a quasi-rms voltage having recurrent periods with first zones containing spurious noise from switching of inverter switches and broad second zones, between the first zones, which are substantially free of spurious noise. The quasi-rms voltage is sampled only during the second zones, so that the samples have a high information-to-noise ratio. The sample signal may be used in a variety of methods to detect and control arc instabilities in gas discharge lamps.

Abstract: A fill-in light emitting apparatus having an illuminating mechanism for emitting illumination light whose color temperature can be varied; a color temperature metering mechanism for measuring the color temperature of the external light; and a color temperature controlling mechanism for varying the color temperature of the illumination light in accordance with color temperature data measured by the color temperature metering mechanism.

Abstract: A method for improving electrical and light producing efficiency in two terminal, direct current, low voltage incandescent lamp dimming wherein a small inductance in series with the power source, lamp, and two terminal controller boosts the voltage supplied to the timing circuitry. Accordingly, the voltage level of the controlling signal applied to the insulated gate of the field effect transistor is increased as well, improving electrical efficiency and allowing for efficient use with a wide range of supply voltage, from 18 volts or more down to as low as one volt. Also a technique is provided whereby, even though using only two terminals, lamp intensity is regulated over a wide range of supply voltage excursions, improving light producing efficiency in incandescent lamps. Also, this same technique proportionally reduces current demand when the supply voltage exceeds that of the lamp, affording increased energy extraction efficiency from batteries.

Abstract: A lamp control apparatus that responds to sudden increases in ambient light by energizing a light bulb for a short period of time. A first voltage comparator is connected to a photocell circuit such that its output normally presents a high impedance to a timing capacitor connected to the input of a second voltage comparator which, in turn, provides a gate signal for a triac power switch. The first comparator will switch to a low impedance output if a sufficient amount of light suddenly appears at the photocell. This low impedance will rapidly discharge the timing capacitor and allow the second comparator to energize the lamp. The timing capacitor will then slowly charge back to a voltage that will cause the second comparator to remove the gate signal for the triac, thereby de-energizing the lamp.

Abstract: A light sensor and light feedback adjustment device is provided for use with a control unit for selectively controlling the light output of at least one lamp of a ceiling-mounted luminaire to which the unit is connected, based at least in part on the level of ambient light feedback to the unit. The device includes a lens holder, a lens element screw-mounted on the lens holder and including a light gathering lens, and an arrangement for, in use, securing the lens holder in place in a ceiling tile of the ceiling on which the luminaire is mounted. The lens holder includes a tubular mounting portion including a central bore therein in which is disposed a fiberoptic bundle that receives light gathered by the lens. A light feedback adjustment arrangement includes an adjustable set screw mounted for movement in a transverse passage located in the lens holder between the lens element and the fiber optic bundle so as to vary the light coupled to the bundle.

Abstract: An operator independent image cytometer having a method for image segmentation. Image segmentation comprises the steps of filtering a digital image of a cellular specimen and thresholding the resultant image. In addition, the thresholding may include the sorting of features extracted from the filtered image. The present invention also includes a method for cytometer autofocus that combines the benefits of sharpening and contrast metrics. The present invention further includes an arc lamp stabilization and intensity control system. The image cytometer has broad applications in determining DNA content and other cellular measurements on as many as 10.sup.5 individual cells, including specimens of living cells. Image segmentation applications include PAP smear analysis and particle recognition.

Abstract: Apparatus for monitoring and controlling the operation of one or more high intensity discharge (HID) lamps. An electronic HID lamp power supply is electrically connected to a power source and to the HID lamps. For each lamp, one or more sensors produce one or more output signals respectively representative of one or more parameters (such as light intensity, color temperature, power consumption, temperature, arc voltage, etc.) which respectively define one or more operational characteristics of the lamps.

Abstract: A method and apparatus for nearly instantaneous and wide dynamic range exposure control in light-based measurement instruments. The excess charge drained from a CCD array by anti-blooming circuitry is effectively monitored and distinguished from leakage current. Detection of the drained charge generates a signal to deactivate the light source exposing the CCD array. The exposure control device includes a unique circuit for detecting the operating state of an anti-blooming circuit associated with a CCD array, and a unique laser light driver that ramps up the light intensity of the laser light source in an approximately exponential manner.

Abstract: Dimmable fluorescent lamp apparatus includes a dimming control element housed in an integral adapter having a base which installs directly on an existing incandescent or other lighting fixture. The adapter mounts a fluorescent illumination element either fixedly or removably and replaceably. The lamp apparatus includes a manually accessible adjustment element connected with the control element and mounted on the adapter. The adjustment element can be an electrical adjustment element or an optical adjustment element.

Abstract: A fill-in light emitting apparatus having an illuminating mechanism for emitting illumination light whose color temperature can be varied; a color temperature metering mechanism for measuring the color temperature of the external light; and a color temperature controlling mechanism for varying the color temperature of the illumination light in accordance with color temperature data measured by the color temperature metering mechanism.

Abstract: In a lighting circuit, a battery voltage is supplied via a DC booster circuit to a DC-AC converter where the voltage is converted to an AC voltage with a rectangular waveform. This AC voltage is supplied to a discharge lamp. At this time, the DC-AC converter controls the frequency of the rectangular wave output from the DC-AC converter in accordance with a signal sent to a bridge type driver from a frequency controller. A lighting detector is provided to detect if the discharge lamp has been lighted. Upon reception of a signal from the lighting detector, the frequency controller sets the frequency of the output voltage of the DC-AC converter in the pre-lighting period of the discharge lamp higher than the frequency of the output voltage of the DC-AC converter after the lighting of the discharge lamp and restricts the inversion of the polarity of the output voltage of the DC-AC converter until a predetermined time passes sfrom the point of the activation of the discharge lamp.

Abstract: A method and apparatus for ionizing a rare gas in a gas type cold cathode lighting source using a high voltage direct current pulse. Direct current pulses are applied to the lighting source, the current flow to the lighting source is sensed, upon ionization of the gas the voltage level of the pulse is reduced and the pulse width is increased so as to provide a proportionally increased constant current high voltage direct current pulsed output, and the polarity of the pulses to the light source is periodically reversed.

Abstract: A photoelectric control circuit that energizes a light bulb at a certain level of darkness and immediately records the total amount of light that results. A delay circuit prevents the new level of light from turning the bulb back off until a even greater amount of light is available. This method of operation provides full power control for a variety of lamps and bulbs without the degraded performance previously associated with reflected light from enclosures and nearby objects.

Abstract: An electroluminescent device used as an illuminating source in a scanner. The device includes at least one solid-state electroluminescent element, which has a transparent electrode with a top surface, a radiation generating stack under the transparent electrode, and a second electrode with a bottom surface under the radiation generating stack. Radiation is generated from the radiation generating stack when a selected voltage source is coupled across the electrodes. Most of the radiation generated is emitted either from the top surface or from (the top and the bottom surfaces). When the scanner scans a medium, the emitted radiation is substantially uniform at least across the top surface of the transparent electrode to create a uniform radiation source for illuminating the medium.

Abstract: A strobe apparatus having a light emitter which emits strobe light and a color temperature converter for varying a color temperature of the strobe light emitted from the light emitter. The apparatus includes a first color temperature detector for detecting a color temperature of the strobe light after being reflected from an object, a second color temperature detector for detecting a color temperature of ambient light reflected from the object, and a color temperature controller. The color temperature controller controls the color temperature of the strobe light detected by the first color temperature detector, so that the color temperature of the strobe light incident upon the object to be photographed is substantially identical to the color temperature of the ambient light detected by the second color temperature detector.

Abstract: The invention relates to a control device for an appliance consuming electric power, especially for the control of lighting or heating. The control element includes a sensor element (V8) for producing a control current or voltage as a result of a light or heat flux received thereby. An amplifier element (V4-V1) boosts the control current of said sensor element (V8) to a sufficient level for controlling one or a plurality of electronic ballasts, which is e.g. a current limiter for a discharge lamp, a regulator for a filament lamp or a heating effect regulator. The electric power required by the amplifier element (V4-V1) of the control device is supplied from said ballast by means of conductors, which also serve as a control line between the control device and the ballast.

Abstract: A correlated color temperature measuring device for measuring the color temperature of light includes a sensor which individually senses plural light components of light incident thereon and for providing plural corresponding digital color component signals representative thereof, a memory which stores correction data for correcting the plural digital color temperature component signals, and a processor which receives the plural digital color component signals from the sensor. The processor accesses the correction data in the memory, corrects the plural color component signals from the sensor based on the correction data and derives a digital signal representative of the color temperature of the incident light. The derived digital signal may be displayed on a digital display or may be outputted on a digital I/O interface in response to a request for digital color temperature information.

Abstract: An apparatus for providing excitation of a vapor discharge lamp includes a control circuit for controlling an oscillator circuit during an ignition mode of the vapor discharge lamp to establish and maintain a substantially constant DC voltage at an output of an oscillator transistor and to establish a current flow through the oscillator transistor at a first current level sufficient to ignite the vapor discharge lamp, and for controlling the oscillator after ignition of the vapor discharge lamp to maintain the substantially constant DC voltage at the output of the oscillator transistor while reducing the current flow through the oscillator transistor from the first current level to a second current level, and in preferred embodiments, includes circuitry to suppress unwanted blocking oscillations and optimize the dynamic range of the control circuitry.

Abstract: The invention relates to a switching arrangement for operation of a high-pressure sodium discharge lamp by means of an adjustable power. Control of the adjustable power takes place by means of a control signal generated by optical sensing means for registering the spectral power of light emitted by the lamp. Registration of spectral power takes place in a first wavelength range between 350 nm and 800 nm.

Abstract: Miniature light-activated lamp control apparatus and the like, including a thin disk-shaped switching unit positionable within a light bulb socket and a thin light conductor having one end attached thereto, the light conductor being extendable through the gap between the electrically conductive inner wall of the socket and the electrically conductive outer surface of the bulb base disposed in the socket, and terminating at the opposite end in a lens for gathering ambient or other light. The switching unit has a first contact on one side for engagement with the socket center terminal, and a second contact on an opposing side for engagement with the center terminal of a light bulb. The unit includes a thin circuit board having control circuitry mounted thereon, such circuitry being positioned to occupy available space between the conical bulb base and the circuit board.

Abstract: A control unit for controlling a strobe light or the like, in particular for use in an alarm system or an emergency locator, is characterized in that a direct current power supply unit is provided which is activated to drive the strobe light when an external power supply unit which is adapted to drive the strobe light is deactivated.

Abstract: A capacitive element is introduced in series with the gate of a switching element in an automatic turn on/off circuit which automatically provides artificial light depending on the ambient light incident on a photo sensitive element of the circuit wherein the capacitive element holds an offset voltage which aids in turning on the switching element and provides a hysteresis in the system which counteracts a flickering effect common to automatic turn on/off circuits controlling an artificial light which employ a photo sensitive device.

Abstract: A lighting fixture is powered from an ordinary power line and has an inverter-type ballast for powering a fluorescent lamp. This ballast comprises an inverter means whose frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals. An optical sensor is located within the fixture in such manner as to intercept part of the light emitted by the fluorescent lamp. This sensor provides a control signal proportional to the amount of light emitted by the lamp, and this control signal is applied to the ballast control terminals in such manner as to regulate the inverter frequency as a function of the light level, thereby correspondingly to regulate the magnitude of the current fed to the fluorescent lamp. By providing a threshold means in combination with high gain in the control loop, the fixture light level may be accurately maintained at any desired value substantially regardless of any changes in magnitude of power line voltage and/or in lamp efficacy.

Abstract: A reference light source device includes a first laser diode emitting a reference light, a harmonic generating unit for generating an nth harmonic of the reference light, where n is an integer, a light generating unit for generating a light signal having a waveform equal to that of the nth harmonic of the reference light, and a photodetector for combining the nth harmonic and the light signal and for generating a first electric signal corresponding to a beat signal obtained by combining the nth harmonic and the light signal. Further, the source device includes a local signal generating unit for generating a local signal, a phase comparator for generating a control signal corresponding to a phase difference between the first electric signal and the local signal, and a driving unit for driving the first laser diode according to the control signal so that a frequency of the beat signal is equal to that of the local signal.

Abstract: A power-line-operated inverter-type ballast powers one or more fluorescent lamps in a lighting fixture. The ballast comprises self-oscillating inverter means wherein the frequency of oscillation can be influenced by receipt of a control signal at a pair of control terminals connected in circuit with the inverter's positive feedback circuit. The ballast also comprises optical sensor means so positioned and constituted as to sense the light level within the lighting fixture and to provide a control signal commensurate with that light level. This control signal is then applied to the control terminals in such manner as to regulate the inverter frequency as a function of the light level, thereby correspondingly to regulate the magnitude of the current fed to the fluorescent lamps.

Abstract: Light control apparatus and method in which commanded changes in luminance in a space are executed in accordance with a rate function generated by a function generator to correspond to adaptability of the human eye to changes in luminance. A luminance sensor detects the luminance to which a person occupying the space was exposed just prior to the commanded change in luminance. The sensed luminance is used to determine the discrimination range of the occupant, and, upon a commanded increase in luminance in the space, the luminance is immediately increased to within the range.

Abstract: A variable color luminaire is arranged for controlling a plurality of light sources of different emission colors to be at predetermined dimming levels by means of dimmers, performing a comparison operation to obtain a quantity-of-light ratio and a reference quantity-of-light ratio from detection signals with respect to light outputs of the light sources detected by detectors, and subjecting the light sources to a quantity-of-light correction by means of a corrector according to results of the comparison operation so as to attain a blended color light as set, whereby the resultant blended color light can be prevented from deviating from the set blended color light even when dimming quantity of the respective light sources is close to upper and lower dimming limits.

Abstract: An apparatus and method of controlling the light intensity in a light source of variable emission affected by a drive signal. Spatial optical integration based upon light summation is incorporated into the accompanying encasement device at a backlight source by means of a light source support structure that allows light not directed toward a viewed surface, such as an LCD, to serve as a control input to the light drive signal.

Abstract: A compact auxiliary circuit modifies the operation of a low-voltage control circuit associated with an electronic dimming gas discharge lamp ballast. The auxiliary circuit modifies the output of the control circuit to reduce the brightness of the lamps when excess ambient light is available, and increases the brightness of the lamps as available ambient light is reduced. The auxiliary circuit is located in a small housing which mounts in a knockout plug of a fluorescent ceiling fixture. In a preferred embodiment, the auxiliary circuit includes a photocell that obtains information on ambient light levels through an ambient light gathering prism mounted through a ceiling tile near the fixture, and connected to the circuit housing by a flexible fiber optic cable. A single auxiliary circuit according to the invention can be connected to vary the brightness of a large number of lamps.

Abstract: In this strobo apparatus, in a strobo controlling circuit in which such self-arc extinction-type gate-controlling type switching device as an IGBT is connected in series with a flash discharge tube to control the flash of the discharge tube, a bias voltage controlling the on/off operation of the above-mentioned gate-controlling type switching device is obtained from a biasing condenser charged with an exciting current of the flashing discharge tube or directly from a power source voltage boosting circuit through a resistance or sub-condenser.

Abstract: A variable color lighting arrangement includes at least first to third light sources and at least another light source, and allows a desired mixed color light to be obtained in a relatively simpler manner, such that an emission color of a temporary light source is first imaginarily set with an emission color of one of the first to third light sources mixed with another emission color of the said another light source, a mixing ratio is calculated with emission colors of remaining two or more of the plurality of light sources including at least the first to third light sources and the emission color of the temporary source, and a required mixing ratio of the respective light sources for obtaining the desired mixed color light is obtained on the basis of the calculated mixing ratio.

Abstract: An auto-starting lamp system comprises an electrodeless high intensity discharge lamp of the type including an arc tube that contains an ionizable fill, an excitation coil surrounding the arc tube for exciting an arc discharge in the ionizable fill at least during steady state lamp operation, and a starter circuit for facilitating arc discharge of the ionizable fill. The system further comprises a controllable r.f. power source for powering the lamp excitation coil, and an electrical network for matching the impedance of the excitation coil to the impedance of the r.f. power source. The impedance-matching network has the same impedance-matching relation during both lamp start-up and steady state lamp operation. A system controller causes the r.f. power source, during lamp start-up, to ramp up in power to a peak level preferably substantially in excess of a steady state lamp operating power level, and then to decrease from the peak level.

Abstract: An atomic clock system employs one of a family of ion trap configurations confining an ion in a potential well, such that a vibrational frequency confined ion may be measured accurately. The ion traps disclassed for use in such atomic clock systems include configurations of ring-shaped conductive members, or sheets of conductive material having circular holes therein. The trap apparatus further has a means to apply an RF field such that the resulting electric field being generated in a space defined by the conductive members has a characteristic of a substantially quadrupole field whereby a charged particle, being injected into the space, is confined in said field, maintaining a dynamic equilibrium condition.

Abstract: Each of a plurality of EL lamps in an instrument panel has its own control circuit for connecting the lamp to an adjustable AC voltage source. Each control circuit includes a photodetector for detecting the intensity of the illumination of its associated lamp, when the lamp is energized. With respect to a given input voltage of the AC voltage source, when the intensity of the light emitted by a given lamp begins to diminish, its control circuit will automatically increase the AC voltage applied across the electrodes of the lamp, thereby maintaining the light intensity of the lamp regardless of its age, for a given AC input voltage to the control circuit. The intensity of each lamp therefore remains consistent throughout substantially the full life of the EL lamp.

Abstract: A gas discharge lamp has a fill mixture with first radiation-emitting substances which emit predominantly in an ultraviolet spectral range, and a further radiation-emitting substance which has an emission line in a lower-frequency spectral range. The intensity at the lower-frequency emission line is monitored and used to control lamp operation. This prevents continued use of lamps whose normal service life has been exceeded, as evidenced by intensity dropoff or frequency drift. This in turn prevents damage to health, in lamps used for medical or cosmetic purposes, or malfunctions in technical manufacturing processes, in lamps used in such processes. Thus, irradiation with unsuitable discharge tubes is prevented. Depending upon the intended lamp application, preferred fill additives may include lithium, cesium, thallium, or sodium.

Abstract: A device for modulating and controlling the level of luminosity output by a lighting facility. The modulation may be of average current or voltage. The device modulates electrical power in a cyclical manner for input to the lighting facility, so that the resulting modulation of the luminosity output serves to exercise the eyes of persons exposed thereto. The average luminosity, and the amplitude and period of modulation can be set and adjusted by the user. The rate of modulation is sufficiently slow that the level of change of luminosity is accommodated by human eyes and is imperceptible through the eyes of persons exposed thereto. In one embodiment, an illuminance sensor is provided to read the actual illumination of a lighted object. The values of the illumination so read are fed back in the device to adjust the luminosity of the lighting facility, so that the object is illuminated in the desired cyclical manner.

Abstract: Device for automatically controlling the lighting level of premises (A) having available one or more openings (B) to the outside. This device acts on means (V, S, E) of masking the openings and on means of artificial lighting with dimmer (L) as a function of a set point value corresponding to a lighting level established by the user and recorded instantaneously. The masking and lighting means are furthermore controlled in a specified order so as to limit the consumption of energy. In certain implementations, this order is determined as a function of the deviation between a measured temperature and a threshold temperature.

Abstract: An anti-cycling device for high pressure sodium lamps detects an abnormal cycling condition by using a fiber-optic cable that extends between an anti-cycling controller board and the lamp itself. An outer end of the cable is arranged so that light emitted by the lamp will be transmitted to the controller board. A photocell mounted on the controller board, at the other end of the cable, transmits a variable magnitude electrical signal to the circuitry on the controller board. The signal varies in accordance with light being transmitted or not transmitted through the cable, as the case may be, corresponding to a cycling condition. In this manner, the controller board is able to detect a cycling condition, and thereby cause the power supply to the lamp to be cut off.

Abstract: This reactor ballast is used for controlling a lamp and comprises a core and winding connected in circuit with the lamp and inductively coupled to the core for developing a magnetic field in the core when the winding is traversed by electric current. The core forms a magnetic circuit for the magnetic field comprising two parts in series with each other in the magnetic circuit, one part being of metallic magnetic material and the other being of ferrite material. A control arrangement is provided for varying the temperature of at least a portion of the ferrite part in a predetermined temperature range just below the Curie point of the ferrite material where its relative permeability decreases steeply in response to small temperature increases.

Abstract: An inverter is powered by the pulsed DC voltage obtained by unfiltered full-wave rectification of the AC power line voltage provided from an ordinary electric utility power line. The output of the inverter is a 30 kHz squarewave voltage having an instantaneous absolute magnitude that is proportional to that of the AC power line voltage. By way of a step-down voltage transformer, the 30 kHz squarewave inverter output voltage is applied to the filament of a low voltage incandescent lamp.