Abstract: A driving circuit includes: a first connecting port for receiving a first signal during a first operating mode; a second connecting port for receiving a second signal during the first operating mode or receiving a third signal during a second operating mode; a first driving unit coupled to the first connecting port and the second connecting port, for driving an LED element according to the first signal and the second signal during the first operating mode; and a second driving unit coupled to the second connecting port, for driving the LED element according to the third signal during the second operating mode; wherein the second operating mode is different from the first operating mode.

Abstract: A driving circuit includes: a first connecting port for receiving a first signal during a first operating mode; a second connecting port for receiving a second signal during the first operating mode or receiving a third signal during a second operating mode; a first driving unit coupled to the first connecting port and the second connecting port, for driving an LED element according to the first signal and the second signal during the first operating mode; and a second driving unit coupled to the second connecting port, for driving the LED element according to the third signal during the second operating mode; wherein the second operating mode is different from the first operating mode.

Abstract: A light emitting diode (LED) tube lamp includes a lamp tube; a first pin and a second pin coupled to a first end of the lamp tube, and a third pin coupled to a second end of the lamp tube; a first rectifying circuit comprising diodes and connected to the first and second pins, and a second rectifying circuit comprising diodes and connected to the third pin and an output terminal of the first rectifying circuit; a filtering circuit coupled to the two rectifying circuits and the LED module, for filtering the rectified signal to produce a filtered signal; an LED module comprising LEDs for emitting light, the LED module configured to be driven by the rectified signal or the filtered signal; and a driving circuit coupled between the two rectifying circuits and the LED module, and configured to drive the LED module.

Abstract: An optoelectronic circuit for receiving a variable voltage containing alternating increasing and decreasing phases. The optoelectronic circuit includes assemblies of light-emitting diodes mounted in series; a current source connected to each assembly by a switch; for each switch, a first comparison module for comparing the current passing through the switch with a current threshold; a second comparison module for comparing a voltage representing the voltage at the terminals of the current source with a voltage threshold; and a control module connected to the first and second comparison modules and designed to control the opening and closing of the switches, during each increasing phase and each decreasing phase, according to signals supplied by the first and second comparison modules.

Abstract: An LED tube lamp is disclosed. An installation detection circuit is configured in the LED tube lamp configured to receive an external driving signal. The installation detection circuit is configured to detect during one or more pulse signals whether the LED tube lamp is properly installed on a lamp socket, based on detecting a signal generated from the external driving signal. The installation detection circuit includes a switch circuit coupled to the pulse generating circuit, wherein the one or more pulse signals control turning on and off of the switch circuit.

Abstract: A LED tube with a safety device is provided. The LED tube is connected with an external power supply, comprises: two conductive needle groups, each of the conductive needle groups includes two needles; at least a LED light-emitting component configured to be electrically connected with the needles; and a plurality of fuses configured at the conductive needle groups, respectively.

Abstract: An LED tube lamp is disclosed. An installation detection circuit is configured in the LED tube lamp configured to receive an external driving signal. The installation detection circuit is configured to detect during one or more pulse signals whether the LED tube lamp is properly installed on a lamp socket, based on detecting a signal generated from the external driving signal. The installation detection circuit includes a switch circuit coupled to the pulse generating circuit, wherein the one or more pulse signals control turning on and off of the switch circuit.

Abstract: A compatible inductor-type circuit structure with direct input from commercial power includes a substrate and a light-source control-loop device. The light-source control-loop device is disposed on the substrate and includes a constant current circuit, plural light source modules, a switch, a commercial power simulation circuit, a high voltage protection circuit, plural bridge rectifier circuits and a limited current protection circuit. The constant current circuit, the light source modules, the switch, the commercial power simulation circuit, the high voltage protection circuit, the bridge rectifier circuits and the limited current protection circuit are connected together electrically. By the abovementioned structures, a luminaire can be installed directly on any lamp holder, without considering whether to remove the ballast. The circuit structure can be compatible with a dedicated LED lamp holder or a lamp holder activated by a ballast, thereby facilitating the usage.

Abstract: The present invention discloses a feedback circuit capable of regulating response according to variation of dimming signal, comprising an error amplifier unit, a bandwidth regulating unit and an optical coupler. This feedback circuit is applied in an LED illumination apparatus comprising a plurality of LED components, an LED driver, a PWM controller, and a dimming circuit unit. When the LED driver and the dimming circuit unit normally work, the bandwidth regulating unit produces an electrical resistance for regulating a feedback signal provided by the error amplifier unit according to a dimming signal of the dimming circuit unit. Therefore, the regulated feedback signal is outputted by the optical coupler for making the PWM controller correspondingly generates a controlling signal to adaptively regulate bandwidth of the LED driver, so as to attenuate an audible noise produced by the LED driver due to instability of the response.

Abstract: An LED tube lamp includes a first rectifying circuit, a second rectifying circuit, an LED lighting module, a mode determination circuit and a mode switching circuit. The first rectifying circuit is coupled to a first pin and second pin and is configured to rectify an external driving signal transmitted from the first pin and/or the second pin. The second rectifying circuit is coupled to a third pin and a fourth pin and is configured to rectify the external driving signal with the first rectifying circuit. The filter circuit is coupled to the first rectifying circuit and configured to filter the rectified signal. The LED lighting module has a driving circuit and an LED module, and is coupled to the filter circuit and is connected to receive the filtered signal. The mode determination circuit is configured to generate a first determined result signal based on the external driving signal.

Abstract: A light emitting diode (LED) tube lamp includes a lamp tube having four pins for receiving an external driving signal; a first rectifying circuit coupled to two of the four pins to rectify the external driving signal; a second rectifying circuit coupled to another two of the four pins to rectify the external driving signal; a filtering circuit coupled to the first and the second rectifying circuits to filter rectified signal; and an LED lighting module coupled to the filtering circuit to receive filtered signal to emit light. The first rectifying circuit further includes a terminal adapter circuit for providing four terminals correspondingly coupled to the four pins. With function of the terminal adapter circuit, the LED tub lamp is compatible with an AC driving mode and a ballast driving mode. The LED lighting module further includes a driving circuit having a controller and a converter circuit.

Abstract: Apparatus and method are disclosed for providing AC line power to lighting devices such as light emitting diodes (“LEDs”). A representative apparatus comprises: a plurality of LEDs couplable to form a plurality of segments of LEDs; a current sensor; and a controller to monitor a current level through an overall series LED current path, and to provide for first or second segments of LEDs to be in or out of the overall series LED current path at different current levels. The controller is configured to, in a first light emitting diode configuration, cause first and second segments of LEDs to be parallel to one another and in the overall series LED current path. The controller is further configured to, in a second light emitting diode configuration, cause first and second segments of light emitting diodes to be coupled in series and in the overall series light emitting diode current path.

Abstract: An induction heating system includes an induction heating coil operable to inductively heat a load with a magnetic field, a detector for detecting a current feedback signal corresponding to a current flowing through the induction heating coil, and a controller for detecting a switching transient in the current feedback signal and determining a resonant frequency of the system based on a characteristic of the switching transient.

Abstract: A lighting installation includes a light fixture having a socket adapted to electrically connect to at least one lamp, the light fixture having a line voltage input, a neutral input and a ground input. Also included is a circuit for suppressing electrical surges including output leads for line voltage and neutral to the socket, a first varistor connecting the line voltage input and ground input, a second varistor connecting the line voltage input and neutral input, a third varistor connecting the ground input and neutral input, a resistor connecting the line voltage input and line voltage output, and a resistor connecting the neutral input and neutral output.

Abstract: An electrical circuit is described that comprises a first string and second LED string coupled in parallel, a first and second transistor, at least one bypass transistor, and a controller. The first transistor is coupled to the first LED string at a first terminal of the first transistor. The second LED string includes multiple LED color strings coupled in series. The second transistor is coupled to the second LED string at a first terminal of the second transistor. The bypass transistor is coupled to one of the color strings. A first terminal of the bypass transistor is coupled to a first terminal of the color string. The second terminal of the bypass transistor is coupled to a second terminal of the color string. The controller controls a gate voltage of the first and second transistors and the bypass transistor to operate all transistors in linear modes.

Abstract: A lighting circuit includes an input unit, an output unit, a rectifying circuit, first and second switching circuits, a dimming signal generating circuit, and first and second control units. The input unit is connected to a control device that outputs an alternating-current voltage. The output unit is connected to a light-emitting unit. The rectifying circuit converts the alternating-current voltage into a rectified voltage. The first switching circuit converts the rectified voltage into a first voltage with a first switching element. The second switching circuit converts the first voltage into a second voltage with a second switching element and outputs the second voltage to the output unit. The dimming signal generating circuit generates a dimming signal. The first control unit controls the first switching element. The second control unit controls the second switching element.

Abstract: When an LED lighting apparatus which is a lighter load than an incandescent lamp or halogen lamp is connected to a dimmer, a malfunction may occur. The invention prevents the occurrence of such malfunction without defeating the purpose of low power consumption of the LED lighting apparatus. More specifically, the LED lighting apparatus includes a rectifier circuit, a light-emitting circuit connected to the rectifier circuit and containing a single or a plurality of LEDs in which current begins to flow when an output voltage of the rectifier circuit exceeds a threshold voltage, and a bypass circuit having a bypass path for making the current flow to the rectifier circuit without passing through the light-emitting circuit, and a detecting unit for detecting the current flowing through the light-emitting circuit, and wherein when the current detected by the detecting unit exceeds a predetermined value, the bypass circuit shuts off the current flowing through the bypass path.

Abstract: An LED with an internal bypass transistor, particularly suited for use in a series wired LED string to keep the string lit in the event of a failure of an LED. In one embodiment, the collector and/or base of the bypass transistor is used as one terminal of the shunt and the emitter is used as the opposite terminal. The preferred embodiment is to use the collector and emitter terminals only with the base terminal open.

Abstract: The present invention introduces a device and a method for driving an LED with an improved power factor without using a voltage detector having a large amount of area and power consumption. The device for driving an LED includes a power supply unit, an LED array, and a current path select circuit. The LED array 320 is connected with the power supply unit in parallel and includes at least one LED string including LED channels LED1 to LEDn that are configured of a plurality of LEDs connected in series. The current path select circuit selects a path of current flowing from output terminals of the plurality of LED channels according to voltage levels of each of the output terminals of the plurality of LED channels.

Abstract: Ballasts and LED drivers are presented for powering at least one light source, in which a shunt circuit provides a high impedance to allow operation of the light source when the AC input power exceeds a power threshold value, and provides a low impedance when the AC input power is below the power threshold value to prevent an output power stage from providing power to the light source.

Abstract: A circuit for driving a LED assembly comprising an LED illumination device. The circuit includes a switch, an inductor, in a series connection with the switch, the switch, in its closed state, charges the inductor and in its open state, allows the inductor to discharge. The circuit includes a current measurement element to measure a current flowing through the inductor and/or the LED illumination device in the open and closed state of the switch, and a comparator to compare a signal representing the current measured by the current measurement element with a reference. The switch, inductor and current measurement element establish, in operation, a series connection with the LED illumination device. An output of the comparator is provided to a driving input of the switch for driving the switch between its open and closed state upon a change of an output state of the output of the comparator.

Abstract: An LED module for use in sign letter channel lights comprises a substrate, a reflector mounted on the substrate, an LED mounted within the reflector on the substrate and a Zener diode shunt element connected in parallel across the LED, a printed circuit board on the substrate, wherein the LED is mounted on the printed circuit board, and an insulating cover. The module may be entirely encapsulated. An LED driving protection circuit provides ground fault protection for a plurality of series connected LED modules.

Abstract: Multiple output channel light source power supply circuits, and methods for protecting, are provided. A front end circuit receives an input voltage and provides a regulated front end DC voltage (FEDC). Voltage converter circuits (VCCs) receive the FEDC and provide a separate associated DC output for each associated output channel. A protection switch is coupled between. In its conducting state, the FEDC is coupled to the VCCs. In its non-conducting state, the FEDC is decoupled. A current sense circuit of a current sensor in parallel with a bypass switch is coupled to the VCCs to provide a current sense output representing current through at least one VCC. A controller circuit places the protection switch in the non-conducting state in response to the current sense output. The bypass switch may be placed in a conducting state to shunt current around the current sensor during normal operation to reduce or eliminate inefficiency.

Abstract: An apparatus, method and system are disclosed for providing AC line power to lighting devices such as light emitting diodes (“LEDs”). A representative apparatus comprises: a plurality of LEDs coupled in series to form a plurality of segments of LEDs; first and second current regulators; a current sensor; and a controller to monitor a current level through a series LED current path, and to provide for first or second segments of LEDs to be in or out of the series LED current path at different current levels. A voltage regulator is also utilized to provide a voltage during a zero-crossing interval of the AC voltage. In a representative embodiment, first and second segments of LEDs are both in the series LED current path regulated at a lower current level compared to when only the first segment of LEDs is in the series LED current path.

Abstract: A processing system may include a plasma source for providing a plasma and a workpiece holder arranged to receive ions from the plasma. The processing system may further include a pulsed bias circuit electrically coupled to the plasma source and operable to switch a bias voltage supplied to the plasma source between a high voltage state in which the plasma source is biased positively with respect to ground and a low voltage state in which the plasma source is biased negatively with respect to the ground.

Abstract: The disclosure relates to a pixel circuit which includes an LED, a storage capacitor, a driving transistor, and first to third switching transistors. The driving transistor is utilized to control connection/disconnection between a power supply voltage and the LED. The first switching transistor receives a first scanning signal for controlling connection/disconnection between a gate of the driving transistor and the power supply voltage. The second switching transistor receives a second scanning signal for controlling connection/disconnection between the storage capacity and a ground voltage. The third switching transistor receives the first scanning signal for controlling connection/disconnection between the storage capacity and a data voltage. The first scanning signal and the second scanning signal are in antiphase to each other. A driving method thereof is also disclosed.

Abstract: A dimming apparatus transmitting control signals with AC power line (10) is applied to an alternating current power source (20), a light emitting diode driving power unit (40), and a light emitting diode unit (30). The dimming apparatus transmitting control signals with AC power line (10) includes an input voltage detection unit (102), a one-shot signal unit (104), an AND gate unit (106), a pulse width modulation dimming signal unit (108), an inductor unit (110), a first switch unit (114), a dimming signal recovery unit (124), and a second switch unit (122). The input voltage detection unit (102) is electrically connected to the alternating current power source (20), the inductor unit (110), and the one-shot signal unit (104). The AND gate unit (106) is electrically connected to the one-shot signal unit (104), the pulse width modulation dimming signal unit (108), and the first switch unit (114).

Abstract: Semiconductor light emitting circuits include semiconductor light emitting diodes that are serially connected between a pair of input terminals. Four layer semiconductor devices, such as Shockley diodes and/or thyristors are also provided, a respective one of which is connected across a respective one of the semiconductor light emitting diodes. The four layer semiconductor devices can allow a string of light emitting diodes to continue to be lit if one light emitting diode fails.

Abstract: Solid state light source driving and dimming systems are provided that enable a plurality of solid state light source (e.g., LED) driver circuits to be coupled to a single AC voltage source. The driver circuits may include constant current circuitry configured to generate a constant AC current from the AC voltage source, and rectifier circuitry configured to generate a DC current to drive the solid state light source (e.g., LEDs). Dimming control includes shunt circuitry operable with a PWM switch to shunt the AC voltage source during certain portions of a PWM signal and to decouple the shunt circuitry from the AC voltage source during other portions of the PWM signal. Shunting the AC voltage source causes the interruption of the DC current to effectively turn off the LEDs. Decoupling the shunt circuitry may improve overall efficiency of power transfer to the LEDs.

Abstract: A solid state lighting unit constituted of: a control circuitry; a single string of light emitting diodes, the single string constituted of a plurality of sections each comprising a plurality of light emitting diodes; and a plurality of bypass paths each responsive to the control circuitry, each of the plurality of bypass paths arranged to provide bypass to a particular one of the plurality of sections, wherein the control circuitry is operative to identify an open circuit condition of a particular one of the plurality of sections, and activate the bypass path arranged to bypass the open circuit section, thereby providing light through sections not exhibiting an open circuit condition.

Abstract: A control circuit used in a lamp system. The lamp system has a first and a second light emitting diode (LED) connected together in series. The control circuit includes a current source for connecting to the first LED to provide a regulated drive current to the first and second LEDs in order to illuminate the LEDs. The control circuit includes a switching component for connecting in parallel with the first LED to divert the driver current from the first LED and provide the driver current to the second LED when the switching component is activated. The control circuit includes a controller for selectively activating the switching component in order to selectively extinguish the first LED.

Abstract: A system and method is provided that eliminates DC bias on at least one of a first electrolytic capacitor and a second electrolytic capacitor of a bipolar junction transistor (BJT) based inverter ballast having a shutdown control circuit in association with only one of at least two BJT switches. A duty cycle dependent capacitor is connected in a series with a bus of the ballast, and a resonant circuit, including primary winding of the output transformer and a resonant capacitor. A balancing/charging resistor is connected at one end between the first electrolytic capacitor and the second electrolytic capacitor, and at another end to the duty cycle dependent capacitor and the resonant circuit.

Abstract: A signal is described herein that provides light output for automotive, rail, ship traffic and/or illumination control that includes a light emitting diode (LED) array, wherein the LED array includes three groups of disparate colored LEDs. A power supply unit provides independent power to each of the three LED groups. Each LED group power supply unit includes an input controlled switch connected to a power line to provide power to the LED array. An input under voltage/over voltage circuit monitors the voltage level of the power line and for enabling and/or disables the input controlled switch according to the voltage level of the power line. A flyback transformer converts the power received from the power line from an alternating or a continuous current signal to a direct current signal output to the LED array.

Abstract: Light emitting device arrays comprising alternate current routes that redirect supplied current in the event of open circuit due to a damaged light emitting element are provided. Furthermore, passive light emitting device arrays that provide current compensation for lost light output are provided.

Abstract: Disclosed is a low cost LED string circuit design that uses an inexpensive half-wave rectification and low-pass filter circuit that is designed to produce minimal flicker in the LED string that is connected to the circuit. The components of the half-wave rectification and low-pass filter circuit are selected in accordance with design principles that prevent glittering and flickering of the LED string. The circuit components of the half-wave rectification and low-pass filter circuit can be embedded in an outlet plug or as a separate independent unit between an AC power plug and the LED string.

Abstract: A communication device such as a cellular or wireless telephone handset has a light display, such as handset cover light or display backlight, synchronized to audio signals from multiple audio sources such as a microphone or AM/FM receiver. The communication device further includes an audio to illumination conversion apparatus for modulating the light display in response to the audio signal. The audio to illumination conversion apparatus has a plurality of audio filter circuits for filtering the audio signal to restrict frequency content of the audio signal to a pass-band. Multiple integration circuits generate an energy content signal indicating an energy level within the pass-band and for the whole spectrum of the audio signal. An illumination modulator generates a modulation pattern for the light display in response to the energy content signals from a predefined light show.

Abstract: First resistors (R1, R2) for setting a forward current value are connected in series to light-emitting diodes (LED 1, LED 2) respectively to constitute first serial circuits (112, 113), which are connected to an input terminal (111). Second serial circuits (115, 116) are connected in parallel to the first serial circuits (112, 113) respectively. The second serial circuits (115, 116) are constituted by a combination of a Zener diode (ZD1) and a second resistor (R3), and another combination of a Zener diode (ZD2) and a second resistor (R4). When a higher voltage than rated voltages of the light-emitting diodes (LED 1, LED 2) is applied, the Zener diodes (ZD1, ZD2) shunt current into the second serial circuit (115, 116) to allow the light-emitting diodes (LED 1, LED 2) to light up at desirable luminance levels different from each other.

Abstract: A light string includes electrical wires to which a number of bulb sockets are connected in series. Each bulb socket defines a receptacle for receiving and retaining a bulb with the bulb in electrical connection with the electrical wires. A shunt member made of alumina is incorporated in the socket. The shunt member is removably disposed in the receptacle of the socket, independent of the bulb, for being electrically connected to the electrical wires in parallel with the bulb whereby when the bulb burns out, the shunt member maintains the current flowing through the wires. The shunt member further includes an insulation sheath surrounding the alumina section.

Abstract: An electronic circuit is shown to initiate and sustain conduction in a gaseous discharge light. A breakover device and snubber network, isolation network, and self-adjusting symmetrical high voltage pulse generator are incorporated into a standard gaseous discharge light assembly typically composed of a power source, gaseous discharge lamp ballast apparatus, and gaseous discharge lamp. The electronic circuit is used (1) for initiating and sustaining conduction of electrical current through gaseous discharge lamps, (2) to provide active suppression of transient voltages both within and external to the gaseous discharge lighting apparatus, and (3) to provide significant attenuation of the propagation of undesirable conducted and radiated radio frequency interference from the gaseous discharge lamp and the overall associated ballast apparatus.

Abstract: Use of NTC (Negative Temperature Coefficient) thermistor devices having base electrical resistances in the range of about 400 to 2200 ohms is disclosed. A string set of series-connected, low voltage incandescent lamps can be configured in which each of the lamp filaments in the set is provided with a shunt circuit that includes one of the temperature sensitive NTC thermistor devices which operates as a filament shunt. The thermistor devices may have relatively low conductivity when connected to a source of operating potential during normal operation of the string set. The devices, however, may become fully conductive in response to an increase in the voltage that exceeds the device's normal voltage drop.

Abstract: An electrical power system to provide a selected voltage to a load such as a fluorescent lighting system is characterized by a winding 3 having a positive end connected to a positive rail and is tapped at a predetermined position for supplying an output terminal with a selected voltage. A first relay contact can electrically connect a neutral end of the winding to a neutral rail to provide one selected voltage or a second relay contact can electrically short-circuit a predetermined number of turns of the winding in response to a request for a second selected voltage. When a fault condition is monitored, a third relay contact can electrically short-circuit the neutral end of the winding to the predetermined position to put the system into a failsafe condition which prevents turns of the winding being open circuit.

Abstract: The circuitry for operating a glow discharge path (GES) comprises a bridge circuit (BC) comprising a polarity switch (S1) and an ignition pulse circuit (ZIS1) in a first bridge branch (B1) and a polarity switch (S2) and an ignition pulse circuit (ZIS2) in a second bridge branch (B2). The glow discharge path (GES) formed between two electrodes (E1, E2) is located in the transverse branch of the bridge circuit (BC). For changing the polarity of the glow discharge path (GES), the polarity switch (S1) of the one bridge branch (B1) can be operated together with the ignition pulse circuit (ZIS2) of the other bridge branch (B2). Thus, each of the two electrodes (E1, E2) of the glow discharge path (GES) can be used as a cathode. The cathode of the glow discharge path is cleaned by the impinging ions.

Abstract: A circuit for turning off an indicator light operates in two phases that provide a first rapid discharge phase and a second slow discharge phase. This sequence dims the light in a visual approximation of the exponential dimming that occurs with lights that operate with power supplies that have capacitors that give a slow turn off. The preferred light is an electroluminescent element that will be called a glow-effect capacitor which stores sufficient charge for slow turn off. When a switch associated with the light is opened, an FET turns on to discharge the capacitor rapidly to a selected voltage. This FET is then turned off and other components discharge the capacitor slowly. The switching signal for this FET is formed as a logic function of the switch position (open or closed) and the occurrence of the selected voltage level on the glow-effect capacitor.

Abstract: An arc diverter detects an arc between the cathode and the anode of a glow discharge apparatus and in response to arc detection, actuates a switching network that triggers a pair of switches to allow a capacitor to discharge toward the cathode along a resonant diverting path and recharge the capacitor for subsequent discharge in an opposite direction. This discharge current effectively short circuits the power supply and extinguishes the arc. The resonant diverting circuit includes two resonant diverting paths and four switches configured in an "H" to hold the capacitor in a charged condition. Alternate triggering of the diagonally situated pairs of switches enables the charged capacitor to discharge in one direction along one of the resonant diverting paths and recharge for subsequent discharge in the opposite direction, along the other of the resonant paths. Both resonant diverting paths provide discharge toward the cathode.

Abstract: Apparatus for operating a discharge lamp comprising a high frequency circuit, sensing means for sensing the absence of an electrical connection between the circuit and the lamp and control means for receiving a non-connection signal and for sending a decrease control signal to the high frequency circuit for decreasing the high frequency power supplied to the lamp in response to the non-connection signal. The sensing means senses the absence of an electrical connection between the circuit terminal to which an electric potential is applied which is less than that applied to the other circuit terminal. By sensing the electrical non-connection between the circuit terminal having the lower potential, it is not necessary to sense the absence of a connection at the other end of the lamp.

Abstract: The electric lamp for series arrangement comprises at least one current-supply wire of nickel wire, copper wire or copper cladded wire. A shortcircuit switch is provided, which consists of a vitreous mass, in which copper powder is dispersed and which is fused with the current-supply wires, and of an oxide skin, which is present on the said current-supply wire at the sealing-in area in the mass. The vitreous mass is electrically conducting. An electrical connection between the current-supply wires is not obtained, however, until the filament burns through and the oxide skin breaks down due to the overvoltage then occurring.

Abstract: A D.C. lamp system having a number of small zener diodes arranged in eleccal parallelism with various lamp current supply wires. The zener diodes are sized so that the collective wattage ratings of the zeners is equal to the arithmetical product of the D.C. supply voltage and the summation of the safe amperages of the lamps in the system. In event of normal lamp burnout, any tendency of the other lamps to also burn out due to excessive current surge is countered by the action of the zener diodes; potential excess current is drained through the zener diodes to ground. A large number of small zener diodes are used in preference to one large zener diode, thereby minimizing the need for heat sinks or special cooling means required by a larger zener diode.

Abstract: An improved operation shunt for series connected incandescent-type lamps is disclosed utilizing a novel shunt material composition comprising an admixture of conductive metal particulates, an inorganic binder, and conductive non-metallic particulates and which is adhesively bonded to an insulative bead member interconnecting the spaced apart lamp inleads.

Abstract: Protection apparatus responsive to a fault condition in a high voltage, high current device to be protected; includes an ignitron and a hydrogen thyratron, connected in parallel across the device under protection, such that in event of a fault in the protected device, current is tandemly shunted away from the faulting device. Both the hydrogen thyratron and the ignitron receive simultaneous triggering signals from a fault-detection circuit upon the occurrence of a fault in the device under protection. Since the hydrogen thyratron responds to the fault-trigger signal more rapidly than the ignitron, it establishes a current-shunting path in the first fraction of a microsecond until such time as the slower-responding ignitron can become conductive and carry the brunt of the current to be shunted away from the faulting protected device.