Abstract: A discharge lamp lighting apparatus includes a resonant circuit (5a to 5d) having a capacitor (C3a to C3d) connected to at least one of primary (P1 to P4) and secondary (S1 to S4) windings of a transformer (T1 to T4), an output of the resonant circuit being connected to a corresponding one of discharge lamps, a triangular wave generator 12 to PWM-control switching elements Qp1 and Qn1that pass a current to the primary winding of the transformer and the capacitor, a lighting monitor unit 8 configured to detect a current passing through at least one predetermined discharge lamp among the discharge lamps and output a detection signal when all of the discharge lamps have lighted, and a PWM comparator to control the switching elements according to the triangular signal and detection signal.

Abstract: An overload protection circuit and method for a fluorescent lamp drive circuit is presented, the fluorescent lamp drive circuit having first and second switches connected in series and a controller adapted to switch the switches on and off alternately. The overload protection circuit is adapted to detect a voltage across the first switch, and to turn off the first switch based on whether the detected voltage exceeds a first threshold voltage.

Abstract: A power converter circuit converts an AC line signal to a DC signal for powering an organic light emitting diode. The circuit uses only capacitive elements to limit current to the LED. Inductive and resistive elements are not included in the circuit to limit current. The absence of inductive components eliminates electromagnetic interference generated by the circuit and avoids circuit components magnetically coupling to one another. The circuit includes complementary MOSFET switches that alternately conduct to convert the AC line voltage into a DC current for powering the LED.

Abstract: A method of driving a lamp of a liquid crystal display device includes generating a control signal; generating a first drive signal using the control signal; generating a second drive signal by shifting a voltage level of the first drive signal; selectively outputting one of a high potential supply voltage and a low potential supply voltage in response to the second drive signal; transforming the selectively outputted voltage; and supplying the transformed voltage to a lamp.

Abstract: A LED dimming control circuit that avoids a higher output voltage than expected is provided. The LED dimming control circuit comprises an inductor, a transistor, a dimming control signal, a feedback signal, a switching control circuit, an error amplifier, and an inverted amplifier. The inductor and the transistor are coupled to a node. The switching control circuit is controlled by the dimming control signal and the feedback signal. The transistor is controlled by the switching control circuit. The output terminal of the error amplifier and the non-inverted input terminal of the error amplifier form a negative feedback path via the inverted amplifier.

Abstract: A ballast including an H-bridge type inverter for driving a lamp and a filter circuit that includes a buck inductor is disclosed. The buck inductor is a primary winding of a transformer, and a secondary winding of the transformer provides power to a controller of the ballast. The controller operates the inverter in various pre-ignition modes of operation such that prior to ignition, the open circuit voltage (OCV) (i.e., voltage across the lamp) and buck inductor current are controlled to transfer sufficient power from the primary of the transformer to the secondary winding of the transformer to power the controller. No switches of the inverter are turned on while there is a non-zero current through the filter circuit.

Abstract: A current fed bipolar junction transistor (BJT) based inverter ballast includes base drive circuits configured to drive respective BJT switches, and high-speed drive reverse peak current limiting circuits, configured to operate in conjunction with the respective base drive circuits.

Abstract: A circuit for driving a light emitting diode (LED), the circuit includes a timer, first to third electronic switches, and a regulator. The timer provides a pulse signal to switch the first and second electronic switches. The first electronic switch provides a first level signal to one end of the LED. The second electronic switch switches the third electronic switch on and off. The third electronic switch provides a third level signal to another end of the LED. The regulator adjusts the pulse signal to be at a predetermined frequency to control the first, second, and the third level signals to alternate between a high voltage level and a low voltage level at the predetermined frequency. The LED is driven to be on and off at the predetermined frequency by the first and third level signals.

Abstract: A drive circuit (100) includes an operational amplifier (OP1) that compares a voltage applied to an inverting input terminal with a reference voltage applied to a non-inverting input terminal, a MOS transistor (M1) that has an output connected to the inverting input terminal of the operational amplifier (OP1) and supplies a current to a load (3) depending on a comparison result of the operational amplifier (OP1), and a switch (SW1) that switches, based on a control signal, between outputting the comparison result of the operational amplifier (OP1) to the MOS transistor (M1) and outputting a predetermined voltage to the MOS transistor (M1) to turn off the MOS transistor (M1).

Abstract: A light source device includes first and second electrodes, an arc tube having a main body section having a discharge space in which the first and second electrodes are disposed with a distance and a sealing section disposed on each of the both ends of the main body section, a primary reflecting mirror disposed on the side of the first electrode, a secondary reflecting mirror disposed on the side of the second electrode, and a current drive device that generates an alternating current for causing the discharge between the first and second electrodes, and power control by controlling the alternating current so that supplying energy in an anodic term of the first electrode becomes smaller than supplying energy in a cathode term.

Abstract: A circuit arrangement for controlling the operation of an electronic transformer (1) whose power supply can be lowered. The electronic transformer (1) is electrically connected to an output of a switch (7), and the switch (7) can be controlled by a control unit (5). A radio interference suppression circuit (8) is coupled to the switch (7) and, according to a control state, which exists on the switch (7), for controlling the starting behavior of the electronic transformer (1), the radio interference suppression circuit (8) can be disconnected from the switch (7) and/or an output (A) of the switch (7) can be short-circuited. A method for controlling the operation of an electronic transformer is also disclosed.

Abstract: There is provided highly efficient discharge lamp lighting apparatus capable of reducing its cost by reducing high withstand voltage components on the secondary side of a high voltage transformer and stabilizing, its circuit operation. A discharge lamp lighting apparatus (1) comprises a high voltage transformer (2), a switching circuit (4) for driving the primary side of the high voltage transformer (2), and a triangular wave generation circuit (15) for determining the operation frequency of the switching circuit (4). The triangular wave generation circuit (15) includes a frequency switching means (25) for switching the operation frequency of the switching circuit (4) between before and after the lighting of a discharge lamp (3). At the secondary side of the high voltage transformer (2), a resonant circuit having a capacitance component consisting of only a parasitic capacitance (CCFL) is also formed.

Abstract: A cold-cathode tube driving apparatus wherein the number of booster transformers has been reduced and the increase in installation space and in cost has been suppressed. This cold-cathode tube driving apparatus comprises a booster transformer (2); a plurality of cold-cathode tubes (3-1 to 3-N); and a time division control circuit (control circuit 6 and time division FETs 4-1 to 4-N) for lighting one or more of the plurality of cold-cathode tubes (3-1 to 3-N) in a time division manner by use of a high frequency voltage after boosted by the booster transformer (2).

Abstract: A step-up/step-down regulator circuit wherein a switch has a terminal connected to an end of an inductor, another terminal grounded, and a control terminal connected to an end of a switch. In this way, performing an open/close control of the switch can indirectly perform an open/close control of the switch, thereby solving the problem that the structure and operation of a switch control circuit will be complicated when the switching between step-up and step-down operation is realized.

Abstract: A circuit device for an LED's driving and stabilizing system includes an AC/DC controllable driving voltage source, a feedback driving controller, an LED demodulation driving controller controllable driving voltage source, an external regulator, and an LED modular device. While various internal conditions or factors of the circuit device may be obtained through integrally or partially setting and computing, the circuit device may also be externally connected to an input signal source according to the characteristics of different attributive conditions to thereby achieve the function of automatic regulation, enabling the LED modular device connected thereto and having been used over a long period of time to have lowered brightness attenuation rate, reduced power loss, reduced heat generation, and accordingly, extended the LED's lifespan.

Abstract: A ballast (e.g. a fluorescent light ballast) includes a primary ballast for powering the lamp from a power supply (e.g., utility line power) and an battery powered ballast for powering the lamp from a battery when the primary power supply is not energized by the power supply. When power supply power is restored to the ballast, the ballast shuts down the battery powered ballast and a switch circuit operably connects the lamp to the primary ballast. The ballast toggles the switch circuit such that the primary ballast detects replacement of a lamp and resets any fault detection or protection circuits (e.g., an end of lamp life circuit) that may have been triggered during the transition from battery power to power from the power supply.

Abstract: A high-power amplifier having a current-adding array is provided for high-speed driving of an inductive element, e.g., a deflection coil of an electron beam gun. The amplifier includes a first voltage node (U1) and a second voltage node (UV), at least one of which is connected to a regulated power supply, and a plurality of first switchable bridges (B11, B12, B13, . . . , B1k) connected in parallel between the first and second voltage nodes. Each switchable bridge includes at least one resistor (R11, R12, R13, . . . , R1k) with a resistance value that is selected so that a first resistor (R11) has a first resistance value WR11 equal to Rmin, a second resistor (R12) has a second resistance value WR12 greater than or equal to WR11 and an n-th resistor has an n-th resistance value WR1n greater than or equal to WR1n?1.

Abstract: A driver circuit or controller flexibly drives either a half-bridge or a full-bridge switching network in a backlight inverter without modification, redundant circuitry or additional components. The driver circuit includes four outputs to provide four respective driving signals that establish a periodic timing sequence using a zero-voltage switching technique for semiconductor switches in the switching network.

Abstract: An exemplary switching power supply circuit (2) includes a power source (20), a pulse width modulation (PWM) circuit (21), a first switching circuit (22), a second switching circuit (23), a first transformer (25), and a second transformer (26). The first switching circuit includes a first transistor (221) and a second transistor (222). The second switching circuit includes a third transistor (231) and a fourth transistor (232). The first transformer includes a first primary winding (251) and a second primary winding (252), and the second transformer includes a third primary winding (261) and a fourth primary winding (262). The switching circuits are controlled by pulse signals from the PWM circuit. When the first and third transistors are switched on, the power source, the first primary winding, and the first transistor form a first closed loop. The power source, the third primary winding, and the third transistor form a second closed loop.

Abstract: A light emitting element driving circuit, which can achieve accurate/high-speed operation even at low voltage supply voltage, comprises: driving current supply, connected to light emitting element in series between first and second power supplies, to supply driving current to the light emitting element according to the voltage of control terminal; current determiner to determine and output the current according to an output light amount of the light emitting element; current/voltage converter to convert the determined current into voltage and output it to the control terminal of the driving current supply if control signal is in a first state, and to electrically shield its output voltage terminal from the control terminal of the driving current supply if the control signal is in a second state; and resetter to connect the control terminal of the driving current supply to the second power supply if the control signal is in the second state.

Abstract: A circuit arrangement for operating a high pressure discharge lamp includes a bridge circuit with at least two switches, a control device controlling the switches. The bridge circuit is a half-bridge circuit having exactly two switches. The control device switches on and off in an alternating manner, the first switch and the second switch of the bridge circuit having a first frequency. When the first switch is switched off for controlling the other switch with a rectangular signal of a second frequency which is greater than the first frequency and a predeterminable connection duration. The circuit also includes a tension measuring device measuring an actual value of tension over the high pressure discharge lamp. A reference device provides at least one upper threshold value for the voltage via the high pressure discharge lamp. A comparison device compares the actual voltage over the high pressure discharge lamp with the threshold value.

Abstract: The lighting device for a discharge lamp includes a bridge type rectifying and converting circuit CR1, feedback circuits FB1, FB2, a chopper circuit CR2, a charge circuit CR3, a resonant circuit CR4 resonates with a high frequency signal and lights discharge lamp DL connected to the output end by the resonant voltage, an inverter circuit CR5 which converts the DC power stored in the charge circuit by an alternate switching action of a pair of switching elements Q1 and Q2 into high frequency AC power, and a switch device connected between a connecting point J3 of capacitors C1, C2 of the charge circuit and a connecting point J2 of a pair of rectifying elements D1, D2. The lighting device for a discharge lamp can correspond to a multiple variation of a power supply voltage by a construction which uses the same switching elements by step-up chopper circuit and by inverter circuit in common and changes duty factor of the switching elements within a predetermined range.

Abstract: A lamp driving circuit (10) for operating a discharge lamp has a series arrangement of a first and a second switching device (Q1, Q2) connecting supply voltage input terminals. An inverter resonant circuit (20, 30) shunts one of the switching devices and has an inverter inductance (L1), an inverter capacitance (C1), and lamp connection terminals (O1, O2). A control circuit (40) controls the switching devices to generate a lamp current (IL) commutating at a commutation frequency. During a first interval of a commutation period, the control circuit renders the first switching device alternately conducting during a first time period and non-conducting during a second time period at a high frequency being higher than the commutation frequency, and during a second interval of the commutation period, the control circuit renders the second switching device alternately conducting during a third time period and non-conducting during a fourth time period at a high frequency being higher than the commutation frequency.

Abstract: The lamp comprises at least one light-emitting diode and an electronic power switch connected in series between a power source and the light-emitting diode. The electronic power switch is controlled by an electronic processing circuit according to the state of a control button connected to a control input of the electronic processing circuit. The button is connected in parallel to the electronic power switch. To detect and reconstitute the state of the button, the electronic processing circuit periodically applies fine turn-off pulses to a control electrode of the electronic power switch.

Abstract: A phase-modulated, double-ended, half-bridge topology-based DC-AC converter supplies AC power to a load, such as a cold cathode fluorescent lamp used to back-light a liquid crystal display. First and second converter stages generate respective first and second sinusoidal voltages having the same frequency and amplitude, but having a controlled phase difference therebetween. By employing a voltage controlled delay circuit to control the phase difference between the first and second sinusoidal voltages, the converter is able to vary the amplitude of the composite voltage differential produced across the opposite ends of the load.

Abstract: A power converter circuit converts an AC line signal to a DC signal for powering an organic light emitting diode. The circuit uses only capacitive elements to limit current to the LED. Inductive and resistive elements are not included in the circuit to limit current. The absence of inductive components eliminates electromagnetic interference generated by the circuit and avoids circuit components magnetically coupling to one another. The circuit includes complementary MOSFET switches that alternately conduct to convert the AC line voltage into a DC current for powering the LED.

Abstract: A circuit (20) for powering a load (50) includes a rectifier circuit (200), a voltage clamping circuit (300), and a DC-to-DC converter (400) such as a buck-boost converter. Voltage clamping circuit (300) is coupled between the rectifier circuit (200) and the DC-to-DC converter (400), and functions to prevent the input voltage (VIN) of the DC-to-DC converter (400) from exceeding a predetermined acceptable level, so as to protect the DC-to-DC converter (400) from damage due to transients in a voltage (VAC) provided by an AC line source (40). Preferably, voltage clamping circuit (300) is realized by an arrangement that includes a voltage divider circuit (320), a voltage sensing circuit (340), and an energy-limiting circuit (360), and is well-suited for use in power supplies and in electronic ballasts for powering gas discharge lamps.

Abstract: An exemplary backlight control circuit includes an inverter, a pulse width modulation (PWM) circuit, and a frequency setting circuit. The inverter is configured to provide an alternating current voltage to a lamp. The PWM circuit is configured to provide a pulse control signal to the inverter. The frequency setting circuit configured to regulate a frequency of the pulse control signal provided by the PWM circuit according to an environment temperature.

Abstract: An exemplary backlight control circuit includes an inverter, a pulse width modulation (PWM) circuit, and a frequency setting circuit. The inverter is configured to provide an alternating current voltage to a lamp. The PWM circuit is configured to provide a pulse control signal to the inverter. The frequency setting circuit is configured to regulate a frequency of the pulse control signal provided by the PWM circuit according to a temperature of the lamp.

Abstract: A control device for controlling power supplied to circuitry is disclosed. The circuitry comprises a plurality of portions, each of said plurality of circuit portions being arranged between a first voltage level source and a second voltage level source, said first and second voltage level sources being adapted to output different voltage levels; said control device being adapted to control power supplied to each of said plurality of circuit portions.

Abstract: A circuit for resetting a display having at least one driver outputting a driving voltage through an output channel to a corresponding data line of a panel comprises a first switch and a second switch. The first switch is actuated by a control pulse to transfer a reset voltage to the data line of the panel. The second switch is actuated by the control pulse to electrically isolate the output channel of the driver from the data line of the panel, wherein the control pulse is asserted during transient periods resulting from power-on and power-off of the display.

Abstract: The described DC to AC inverter efficiently controls the amount of electrical power used to drive a cold cathode fluorescent lamp (CCFL). The output is a fairly pure sine wave which is proportional to an input control voltage. The output waveform purity is ensured by driving a symmetrical rectangular waveform into a second-order, low pass filter at the resonant frequency of the filter for all conditions of line voltage and delivered power. Operating stress on the step-up transformer is minimized by placing the load (lamp) directly across the secondary side of the transformer. When configured to regulate delivered power, the secondary side may be fully floated which practically eliminates a thermometer effect on the operation of the lamp. All of the active elements, including the power switches, may be integrated into a monolithic silicon circuit.

Abstract: A method for driving a lamp is described includes generating a light controlling DC electric field E with a desired direction and a desired strength inside the lamp such as to obtain a desirable ion distribution inside the lamp. The lamp is supplied with a commutating current with a DC component, having a constant current intensity and a duty cycle differing from 50%. By setting the duty cycle, it is possible to set a certain average value of the lamp current, allowing the efficacy and/or color temperature of the lamp to be influenced.

Abstract: The present invention relates generally to a simple, low cost ballast for fluorescent lamps that incorporates an integrated circuit and a number of ballast protection functions to cost effectively enhance its reliability. End of lamp life circuitry is provided to shut down the ballast when rectification currents due to lamp aging exceed a predetermined level. This circuitry also functions to stop the ballast operation when the lamp's voltage exceeds a predetermined cutoff level for a set period of time. Re-ignition circuitry is provided that restarts the ballast when new lamps are installed without shutting off the ballast. Multiple striking attempt circuitry is provided that initiates a predetermined number of striking attempts such that cold or old lamps are quickly ignited without the introduction of excessive flickering.

Abstract: A discharge lamp lighting circuit includes a DC/AC converter, a starting circuit, a control unit, a plurality of switching elements driven by the control unit and a series LC resonance circuit. At the time of lighting the discharge lamp, the driving frequency of the switching elements is set to a value higher than a resonance frequency at a time of lighting the discharge lamp thereby to drive and control the switching elements. When the driving frequency reduces and the extinction of the discharge lamp is detected, the driving frequency is shifted to a frequency region which is higher than a resonance frequency at a time of extinguishing the discharge lamp thereby to restart the lamp. Further, when the driving frequency reduces to a value lower than the resonance frequency at a time of lighting the discharge lamp during the lighting of the discharge lamp, the driving frequency is restored to a frequency region higher than the resonance frequency at a time of lighting the discharge lamp.

Abstract: An apparatus of driving a lamp for a display device is provided. The driving apparatus includes an inverter (920), a lamp current sensor (940), and an inverter controller (930). The lamp current sensor (940)senses a current flowing in the lamp and output a feedback signal having a magnitude depending on the sensed current. The inverter controller (930) compares a dimming control signal from an external device with the feedback signal and controls the inverter (920) based on the comparison. The inverter (920) includes a transformer (T1) for applying a lamp drive voltage to a lamp for turning on or off the lamp and a voltage sensor (928) sensing the lamp drive voltage. The inverter (920) adjusts a turns ratio of the transformer in accordance with the sensed lamp drive voltage.

Abstract: A lamp driving device includes first, second, and third voltage converters. The first voltage converter converts a direct current (DC) power voltage to a first pulse voltage. The second voltage converter converts the DC power voltage to a second pulse voltage. The third voltage converter generates a high alternating current (AC) voltage based on the first and second pulse voltages. The lamp driving device generates the high AC voltage without a transformer, so that a manufacturing cost of a display apparatus adopting the lamp driving device may be reduced.

Abstract: To avoid the phenomenon of unsightly flickering in images projected by the projector, in high pressure discharge lamps—especially in high intensity discharge lamps, such as high pressure mercury lamps, metal halide lamps, and xenon lamps—that are used in projectors, even in the presence of the phenomenon of cyclical modulation of the lamp voltage by the returning the light spectrum when the light reflected by the dynamic color filter returns back through the optical system to the lamp, at least during steady operation of the discharge lamp (Ld), a target lamp current signal generation circuit (Up) acquires multiple lamp voltage detection signal (Sv) over a period that is at least as long as the color order cycle of the dynamic color filter (Of) and generates a target lamp current signal (St) based on the multiple lamp voltage detection signals (Sv) that were acquired.

Abstract: The present invention discloses a single-channel comprehensive protection circuit of a self-excitation half-bridge series resonant circuit having a single lamp output, including a DC block capacitor C3, a first partial pressure resistor R1, a second partial pressure resistor R2, a rectifying diode D1, a filter and integral capacitor C4, a release resistor R3, a diac D2, a filter capacitor C5, a filter resistor R4, wherein the method of one point of loading point A at the fluorescent lamp filament is used. The present invention normalizes the treatment of abnormal signals for over-current, over-voltage and end of lamp life state etc. in order to replace the conventional design of multi-channel and multi-point sampling for simplifying the circuit, reducing the cost and space, increasing reliability, and facilitating miniaturization development of the electronic lighting products.

Abstract: A driving device for driving discharge lamps (14) includes a first pulse circuit (11), a second pulse circuit (13), and a primary driving circuit (12). The first pulse circuit includes an input end, a first output end (1), and a second output end (2). The second pulse circuit includes an input end, a third output end (3), and a fourth output end (4). The primary driving circuit is connected between the first pulse circuit and the second pulse circuit for generating drive signals. The second output end of the first pulse circuit is connected to the third output end of the second pulse circuit, and the fourth output end of the second pulse circuit is connected to ground.

Abstract: A ballast integrated circuit (IC) for driving a first switching element and a second switching element includes: a variable gain amplifier (VGA) connected to a first input terminal connected to a resistor, for generating an output current signal according to a resistance value of the resistor and a gain control signal; a preheating/ignition controller connected to a second input terminal connected to a capacitor, for generating an output current signal and an output voltage signal acting as the gain control signal according to a voltage of the second input terminal; an active zero-voltage controller for generating a hard-switching current signal and an active zero-voltage switching current signal, such that it adjusts the voltage of the second input terminal according to switching states of the first switching element and the second switching element; an oscillator for generating an oscillation signal upon receiving the output current signal from the variable gain amplifier (VGA); and a dead-time controller f

Abstract: A circuit for generating a high voltage alternating current to drive a load has a current source having a first terminal and a second terminal. The circuit further has an output terminal and a circuit ground terminal. A first switch will conduct between the first terminal of the current source and the circuit ground terminal when the first switch is closed. A second switch will conduct between the first terminal of the current source and the output terminal when the second switch is closed. A third switch will conduct between the second terminal of the current source and the circuit ground terminal when the third switch is closed. A fourth switch will conduct between the second terminal of the current source and the output terminal when the fourth switch is closed. A load is coupled to the output terminal and the circuit ground terminal.

Abstract: A plasma-generation power-supply device includes a transformer connected to an alternating-current power-supply, a rectifier connected to the transformer, an inverter connected to the rectifier, a reactor inserted in series in a power line of an ozonizer that is supplied with power from the inverter, and a controller that controls the inverter. The controller detects the current flowing to the ozonizer with a current detector and provides a control that keeps power applied to the ozonizer constant.

Abstract: There is provided a process for operating a High Intensity Discharge (HID) lamp, having stable and transient operating phases, by a digitally controlled circuit that includes a DC supply and an inverter. During the stable operating phase of the lamp, the inverter's input DC voltage is maintained at a value depending on the lamp voltage.

Abstract: An electronic ballast for driving a high intensity discharge (HID) lamp is provided. The electronic ballast includes a voltage boost stage for receiving a DC input voltage and outputting a boosted DC output voltage with a controlled current. It further includes a switching stage for converting the boosted DC output voltage to a switched AC voltage capable of driving the HID lamp. An integrated circuit (IC) is coupled to the voltage boost stage and the switching stage for controlling both. The IC includes a lamp power control circuit comprising a sensing circuit for sensing an output current from the switching stage and the boosted DC output voltage, a current control loop which controls the lamp power if the lamp current is at a maximum level and a power control loop which controls the lamp power if the lamp current is below a maximum level. The IC also includes a controller unit interface and provides an ignition mode and a regular operation mode.

Abstract: A computing circuit computes a target value of a current to be supplied to a discharge lamp and generates a pulse control signal for superpose a pulse current. Furthermore, the computing circuit controls a current control circuit so that a pulse current is superposed on a lamp current at a predetermined cycle and power supplied to the discharge lamp is kept constant. For that purpose, the computing circuit lowers a DC current level of the lamp current when a pulse current is superposed on the lamp current, and exercises control so that an integrated amount of power at a predetermined cycle is equalized to a predetermined integrated amount of power.

Abstract: A lighting device for high-pressure discharge lamp for lighting the high-pressure discharge lamp by lowering or raising a DC voltage applied to an input side by a DC/DC converter circuit, then converting the DC power into an AC power by a DC/AC inverter circuit, supplying the AC power to the high-pressure discharge lamp and lighting the high-pressure discharge lamp, wherein when the polarity of the current of the high-pressure discharge lamp lit by the substantially rectangular wave is inverted, the output voltage of the DC/DC converter circuit is set to 1.5 times or more as large as the voltage at the stable lighting time of the high-pressure discharge lamp.

Abstract: In the current detection circuit that detects the output currents of a switching power supply circuit, an improved current detection circuit makes it possible to detect the output current directions of power supplies solves the malfunction of the power supplies vibrating or diverging during changes in load state and during parallel operation, and thus implements stable operation. The direction of an output current I2 can be detected by using the current detection circuit 8 that has multiple switching elements S1 to S4 each operating synchronously with an inverter circuit.

Abstract: A lamp driving apparatus of a liquid crystal display device includes m lamp groups in which a plurality of lamps generating light are disposed; n (n<m) inverter parts to generate an AC voltage for driving the lamps; an inverter controller to control the inverter parts; and a multiplexer to selectively supply the AC voltage generated at the n inverter parts to the n lamp groups among the m lamp groups. In each frame, a clock signal is divided into n divided signals. Different sets of lamp groups are driven during each of the divided signals.

Abstract: A method, apparatus, and system for compensating for lamp lumen depreciation. The method includes operating the lamp under rated wattage for a period towards the first part of operating life of the lamp. Operating wattage is increased at one or more later times. Energy savings are realized. The increases also restore at least some light lost by lamp lumen depreciation. The apparatus uses a timer to track operating time of the lamp. A few wattage changes made at spaced apart times can be made in a number of ways, including changing capacitance to the lamp, or using different taps on the lamp ballast.