Abstract: Systems, methods, and apparatus for a circuit with power factor correction (PFC) are disclosed. In one or more embodiments, the disclosed method comprises providing, by a single-stage power converter, a delay in phase between a peak current command and a rectified input voltage such that a phase of a transformer current intentionally lags behind a phase of the rectified input voltage to maintain a power factor (PF) level and a total harmonic distortion (THD) level for the single-stage power converter. In one or more analog embodiments, a resistor and a capacitor are implemented into a conventional single-stage power converter to provide the delay in phase between the peak current command and the rectified input voltage. In one or more digital embodiments, a controller within a conventional single-stage power converter exclusively provides the delay in phase between the peak current command and the rectified input voltage.

Abstract: There is provided an output circuit for supplying an output current to a load coupled to an output terminal in response to an input signal. The output circuit includes an output transistor for supplying the output current to the output terminal, an output-drive circuit for driving the output transistor, a constant-current limiting circuit for generating a current control signal for limiting the output current to a predetermined current value, and a control circuit for implementing a control such that the output current is controlled on the basis of the current control signal if a voltage at the output terminal is at a predetermined voltage, or less after the input signal is supplied while the output transistor is driven by the output-drive circuit if the voltage at the output terminal is in excess of the predetermined voltage.

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 device for an AC power supply comprising at least two lighting groups, wherein each lighting group has a group input and a group output and at least one LED, wherein the at least one LED is arranged between the group input and the group output, wherein the lighting groups are connected to one another in series.

Abstract: An LED lighting device includes light emitting diode, a current control circuit having a first series circuit of first and second switching elements, a second series circuit of third and fourth switching elements, and a condenser, which is configured so that the first and second series circuits are parallel connected and the condenser is connected between a connection point of the first and second switching elements and a connection point of the third and fourth switching elements, and a control circuit for alternatively on-off controlling a pair of the first and fourth switching elements and a pair of the second and third switching elements.

Abstract: A motor control device is electrically connected with a motor. The motor control device includes a controller and a driving circuit. The controller has a default value of time and generates a first driving signal and a second driving signal. The driving circuit includes a first switching element and a second switching element, the first switching element and the second switching element receive the first driving signal and the second driving signal respectively, and the first switching element and the second switching element are switched on or switched off alternately according to the first driving signal and the second driving signal respectively, so as to drive the motor to operate.

Abstract: A control means has an adjustment function in a microprocessor to adjust variations in an output to a discharge lamp due to variations in components by correcting a duty ratio of a PWM signal for varying an operating frequency of an inverter circuit so that a detected value of a second detection circuit falls within a target range. The microprocessor switches paths to transmit the PWM signal between a path passing through a feedback circuit and a path passing through a voltage follower circuit by switches a switch circuit to supply the signal through the path passing through the voltage follower circuit in adjusting output variations in the preheating mode and the starting mode.

Abstract: Respective pulsed power supplies for plasma opening switches each produce a first current and a second current during a power pulse and a difference between the first current and the second current during a terminal portion of the power pulse. The pulsed power supplies are initiated or adjusted in response to measured opening times of the plasma opening switches in order to minimize or eliminate a need for command triggered opening of the plasma opening switches. Command triggered opening may occur in real time for a shot as needed in response to asymmetry of opening times of the plasma opening switches in the array during the shot.

Abstract: An LED lamp protecting circuit includes an LED lamp, a constant current source and a buffer circuit. The constant current source includes positive and negative input terminals, positive and negative output terminals and a switch. The buffer circuit is connected between the negative output terminal and the LED lamp. The buffer circuit includes a charging capacitor, a first NPN transistor and a second PNP transistor. An emitting electrode of the second transistor is connected to the LED lamp. A collecting electrode of the second transistor is connected to the negative output terminal. The charging capacitor is connected between the emitting electrode of the second transistor and a ground. A collecting electrode and an emitting electrode of the first transistor are respectively electrically connected to a base electrode of the second transistor and the ground.

Abstract: A light source driving circuit for powering multiple light sources in a vehicle includes multiple current limiters and a balance controller. The current limiters are coupled to the light sources for adjusting currents of the light sources respectively. The balance controller coupled to the current limiters can control the current limiters such that a current flowing through each of the light sources is substantially the same as a first target current. Moreover, the balance controller can control the current limiters in response to a brake of the vehicle such that a current flowing through each of the light sources is substantially the same as a second target current.

Abstract: An LED lamp protecting circuit includes an LED lamp, a constant current source and a buffer circuit. The constant current source includes positive and negative input terminals, positive and negative output terminals and a switch. The buffer circuit is connected between the negative output terminal and the LED lamp. The buffer circuit includes a charging capacitor, a first NPN transistor and a second PNP transistor. An emitting electrode of the second transistor is connected to the LED lamp. A collecting electrode of the second transistor is connected to the negative output terminal. The charging capacitor is connected between the emitting electrode of the second transistor and a ground. A collecting electrode and an emitting electrode of the first transistor are respectively electrically connected to a base electrode of the second transistor and the ground.

Abstract: A nanoelectromechanical (NEM) device and a method of making same employ a laterally extending nanowire. The nanowire is grown in place from a vertical side of a vertically extending support block that is provided on a horizontal surface of a substrate. The nanowire is spaced from the horizontal surface. The NEM device includes a component that is provided to influence the nanowire.

Abstract: A high conversion efficiency inverter circuit by providing the current-mode resonant type efficient in using a power source.

Abstract: A controller for a driving circuit of power source comprises a frequency generator, a pulse width modulator, and a driving device. The frequency generator comprises a latch circuit. The frequency generator provides a pulse signal at a first frequency after the controller is started. After the frequency generator receives an indicating signal, the frequency generator changes the frequency of pulse signal from the first frequency to a second frequency and locks the frequency of pulse signal at the second frequency. The pulse width modulator provides a PWM signal according to the pulse signal and a feedback signal which indicates a status of electric power supply of the driving circuit. The driving device controls semiconductor switches according to the PWM signal.

Abstract: A ballast (10) for powering at least one gas discharge lamp (70) in a program start mode comprises an inverter (200), a resonant output circuit (400), and a control circuit (600). During operation of ballast (10), control circuit (600) monitors a voltage within resonant output circuit (400). When the monitored voltage reaches a first specified level that is indicative of sufficient filament preheating, control circuit (600) maintains the inverter operating frequency at a first present value for a preheating period so as to provide preheating of lamp filaments (72,74). Following completion of the preheating period, control circuit (600) allows the inverter operating frequency to decrease. When the monitored voltage reaches a second specified level that is indicative of sufficient ignition voltage, control circuit (600) maintains the inverter operating frequency at a second present value for an ignition period so as to provide ignition of lamp (70).

Abstract: A discharge lamp lighting circuit includes a plurality of discharge lamps, a driving circuit, a control circuit, an open protection circuit, which are connected in series. The open protection circuit includes an open control circuit, a delay circuit, and a plurality of open detecting circuits connected in series. Each of the open detecting circuits is connected to a corresponding one of the discharge lamps. One terminal of the open control circuit is connected to the control circuit, and the other terminal of the open control circuit is connected to one terminal of the delay circuit and a predetermined one of the open detecting circuits. The other terminal of the delay circuit is connected to another predetermined one of the open detecting circuits and ground.

Abstract: A lighting device (132) includes a circuit having a power supply and a plurality of light emitting diodes (120) connected in series with the power supply. The plurality of light emitting diodes (120) includes at least two groups of series-connected light emitting diodes, the groups of series-connected light emitting diodes being connected in series. A different optically isolated field effect transistor (U3-U5) is connected in parallel with each group of series-connected light emitting diodes, for selectively shunting around the group of series-connected light emitting diodes. A different capacitor (C8-C10) can also be connected in parallel with each group of series-connected light emitting diodes. A controller (U2) is connected to a gate of each of the optically isolated field effect transistors (U3-U5) for selectively turning the optically isolated field effect transistors (U3-U5) on and off.

Abstract: A circuit is used for driving a plurality of LEDs by an external voltage source. The LEDs are coupled in series. The circuit comprises a plurality of switches coupled to the LEDs in parallel, respectively, for individually controlling the brightness of the LEDs. The circuit further includes a plurality of Pulse-Width Modulation (PWM) signals coupled to the switches, respectively, for individually controlling the switches.

Abstract: An exemplary backlight control circuit (200) includes two load circuits (210), a pulse width modulation integrated circuit (PWM IC) (250) having a current sampling pin (251), a switching circuit (270), a first input circuit (230) and a second input circuit (240) including an input resistor. Each load circuit includes a backlight (211, 221) and an output end (212, 222). The first input circuit includes a diode (231), a resistor (232), a capacitor (233) and a voltage division resistor (234). A negative terminal of the diode is connected to ground via the resistor and the capacitor respectively, and is connected to the switching circuit. A positive terminal of the diode is connected to one of the output end of the load circuits. The other one of the output ends of the load circuits is connected to the current sampling pin via the input resistor.

Abstract: An efficient and flexible current-mode driver delivers power to one or more light sources in a backlight system. In one application, the current-mode driver is configured as an inverter with an input current regulator, a non-resonant polarity-switching network, and a closely-coupled output transformer. The input current regulator can output a regulated current source in a variety of programmable wave shapes. The current-mode driver may further include a rectifier circuit and a second polarity-switching network between the closely-coupled output transformer and a lamp load. In another application, the current-mode driver delivers power to a plurality of light sources in substantially one polarity by providing a regulated current to a network of time-sharing semiconductor switches coupled in series with different light sources coupled across each semiconductor switch.

Abstract: A ballast (10) for powering a gas discharge lamp load (30) comprises an inverter (100), an output circuit (200), and a fault detection circuit (300). During operation, fault detection circuit (300) monitors a first signal and a second signal within output circuit (300) and sets a fault threshold in dependence on the second signal. The second signal is indicative of the type of lamps in the load (30). In response to the first signal exceeding the fault threshold, fault detection circuit (300) issues a shutdown command directing the inverter (100) to cease operation.

Abstract: A liquid crystal monitor (LC monitor) illuminating apparatus utilizes a fluorescent lamp. The lamp is provided in a backlight portion to illuminate a liquid crystal monitor from behind. The fluorescent lamp is activated by a direct-current (DC) lighting circuit that is provided with a switching circuit which reverses the polarity of the DC lighting circuit. A digital camera with a liquid crystal monitor including an LC monitor illuminating apparatus is also disclosed.

Abstract: A fluorescent lamp includes: an emission tube for generating a luminous flux; a first filament provided at one end of the emission tube; a second filament provided at another end of the emission tube; first current regulator having a first impedance; a first electrode pin coupled to one end of the first filament via the first current regulator; a first switch coupled in parallel to the first current regulator; a second switch; a second electrode pin coupled to another end of the first filament via the second switch; and a control circuit for controlling the first switch and the second switch so as to be opened or closed. The control circuit doses the first switch and the second switch before the fluorescent lamp is lit and during a nominal lighting period after the fluorescent lamp is lit, and opens the first switch and the second switch during a power conservation lighting period following the nominal lighting period.

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: Circuit arrangement for igniting and operating gas discharge lamps, in particular high-pressure gas discharge lamps. The circuit arrangement comprises four controllable switches (S1, S4) which are interconnected to form a full bridge, in which a gas discharge lamp (EL) is to be arranged in the bridge branch of the full bridge. After the ignition and operation of the gas discharge lamp (EL), a warm-up operation is carried out in which there is a switch-over between the two bridge diagonals (S1, S4; S2, S3) respectively. The gas discharge lamp (EL) is ignited by way of a series resonant circuit (L1, C1) which is coupled to the bridge branch, with two series-connected switches (S1, S2) of the full bridge being permanently open and the other two switches (S3, S4) being switched on and off alternately at a high frequency.

Abstract: A discharge-lamp illumination circuit has a DC power supply circuit, a DC-AC conversion circuit, and a control circuit for controlling a voltage from the DC power supply circuit. The DC power supply circuit has a transformer and a first switching element connected in series with a primary coil of the transformer. The activation/deactivation of the first switching element is controlled by the control signal from the control circuit. The transformer is equipped with secondary coils equal in number with the discharge lamps. Each secondary coil is equipped with a second switching element whose activation or deactivation is controlled by a signal from the control circuit. The secondary coils provide different voltages by means of control of the second switching elements.

Abstract: A circuit arrangement for starting and for operating high-pressure lamps makes an increased transfer voltage available to the discharge lamp. The increased transfer voltage is generated by voltage doubling across a rectifier unit by means of a charging capacitor (LK), separated into two individual capacitors (C1, C2), the common midpoint (M) of the capacitors (C1, C2) being connected to the two network inputs of the rectifier unit.

Abstract: Provided is an apparatus for controlling the power supplied to a discharge lamp by detecting the voltage and current of the lamp's electric supply line. A microcomputer monitors power consumption of the discharge lamp by multiplying the voltage and current detected in the supple line to determine the input power and produces a representative control signal. The actual input power is compared with a preset input power, based upon the signal, and the power consumption of the discharge lamp is controlled in accordance with the results of the comparison.

Abstract: A discharge lamp lighting device which comprises a DC power source for generating a voltage necessary for a discharge lamp from a DC power source, a control circuit for calculating a power required by the discharge lamp to perform feedback control over the DC power source, a polarity switching circuit for switching polarities of an output of the DC power source to apply the output to the discharge lamp, an ignitor for superposing a high pulse voltage to the discharge lamp at the time of starting the discharge lamp, and a capacitor which forms a closed circuit together with the ignitor, wherein, in order to suppress excessive charging and discharging currents flowing through the capacitor when the polarities of the polarity switching circuit are switched, the control circuit controls the polarity switching circuit to be operated at a low frequency and simultaneously be chopper-operated at a high frequency.

Abstract: A new method of control of high voltage gaseous conductor lamps is herein provided allowing the selective control of the operation of such lamps in a single, or multiple lamp series-connected, current regulated supply circuit, through selective shorting of said lamps with semiconductor devices. The method provided herein also allows selective operation of an infinite number of lamps on a single supply circuit.

Abstract: A discharge-lamp lighting device stably lights and controls a discharge lamp suitable for use in a vehicle. In the discharge-lamp lighting device, an inverter for receiving DC power from a DC step-up circuit supplies AC power to the discharge lamp. Further, a start-discharging circuit applies a high voltage for effecting start discharging to the discharge lamp. A lamp current controlling circuit decides the value of a current to be supplied to the discharge lamp, based on both the luminous efficiency of the discharge lamp, which varies depending on a voltage applied to the discharge lamp and a voltage for the discharge lamp, which has been detected by a voltage detector circuit. A step-up controlling circuit controls a voltage output from the DC step-up circuit in such a manner that the decided value of current coincides with the value of a current to be supplied to the discharge lamp, which has been detected by a current detector circuit.

Abstract: An apparatus for lighting a discharge lamp is provided with an inverter circuit 3 for causing an input power supply 2 to generate the voltage required for a discharge lamp 1, a rectifying smoothing circuit 4 for rectifying and smoothing the output of the invertor circuit 3, a feedback control circuit 8 for computing the power required for the discharge lamp 1 so as to control the feedback control circuit 8 in the feedback mode, a polarity switching circuit 9 for switching the polarity of the rectified and smoothed output to apply the output to the discharge lamp 1 with a low-frequency square wave, and an ignitor 11 for superposing a high-voltage pulse on the discharge lamp 1 when the discharge lamp 1 is started.

Abstract: A lighting circuit for a metallic halide lamp for vehicular headlight applications is disclosed. Included are a pair of input terminals between which a battery is connected for feeding the lamp via a normally open relay switch which is closed upon energization of an associated relay coil. The relay coil is connected in series with an operator actuated lamp switch and a protection switch, so that both lamp switch and protection switch must be closed to energize the relay coil and hence to close the relay switch. The protection switch is automatically opened to deenergize the relay coil when the battery develops overvoltage or when the lamp will not glow upon closure of the lamp switch. In an alternate embodiment, the protection switch is also opened in response to the development of overcurrent or overvoltage by a d.c. voltage booster circuit included in the lighting circuit.

Abstract: A dimming circuit for a discharge lamp (5) arranged in series with two electric coils (3, 4), one of which is by-passed by a semiconductor switching element (6).The control circuit of the semiconductor switching element (6) includes a series arrangement of a resistor (15) and a capacitor (16) connecting a main electrode to the control electrode. The inductance of the by-passed coil (3) is chosen such that the semiconductor switching element (6) is made conductive on reignition of the lamp. The electric losses of the dimming arrangement are low.

Abstract: In a method of operating a photochemotherapy chamber for the irradiation of a patient with long wave ultraviolet light, a prescribed dosage is first selected. The prescribed dosage is then automatically converted into the time duration that an ultraviolet source should be energized to deliver said dosage by monitoring the line voltage and the total hours of operation of the ultraviolet source and adjusting said time duration accordingly.

Abstract: A television receiver includes a conventional tri-color cathode ray tube display system having horizontal and vertical scansion systems. Conventional signal receiving and processing circuitry recovers picture, sound and scansion synchronizing information. A high voltage shutdown circuit is responsive to excesses of either high voltage or CRT beam current. The former being detected by a resistance divider coupled between high voltage and ground while the latter is sensed by a resistor placed in series with the secondary winding of the horizontal deflection transformer. A PNP, NPN transistor pair configured to form a switch analogous to a silicon controlled rectifier responds to detected excesses of beam current or high voltage and loads down the operating supply to the horizontal scansion oscillator to terminate high voltage generation. The transistor pair accommodates a degenerating network to reject false triggering.