Abstract: Each of discharge lamp lighting apparatus that are connected to a common line includes a sawtooth-wave oscillator to generate a sawtooth signal for PWM-controlling a plurality of switching elements passing a current through a primary winding of a transformer and a capacitor of a resonant circuit connected to a discharge lamp, a PWM comparator controlling the plurality of switching elements according to the sawtooth signal, and a pulse synchronization circuit providing the common line with a synchronization pulse signal based on a pulse signal in relation to the sawtooth signal, and when receiving a synchronization pulse signal from the common line, synchronize the oscillation frequency of the sawtooth signal with the frequency of the synchronization pulse signal from the common line. So that a voltage of aligned frequency and phase is applied to one end of each discharge lamp.

Abstract: A multi-discharge tube lighting apparatus connectable to a power source comprising a first output terminal and a second output terminal respectively outputting voltages of opposite phases, the lighting apparatus comprises first to n-th discharge tube units where n represents an integer of two or more, each of which has a first end connected to the first output terminal and a second end connected to the second output terminal and comprises at least one discharge tube, a first winding, and a second winding, which are connected in series between a first end and a second end. The first winding of the first discharge tube unit is electromagnetically coupled via a transformer to the second winding of the n-th discharge tube unit. The first windings of the second and subsequent discharge tube units are electromagnetically coupled via transformers to the second windings of the previous discharge tube units, respectively.

Abstract: A current balancing device includes: a power supply that outputs sinusoidal alternating-current; and a plurality of series circuits, each of the series circuits including a full-wave rectifier, one or more of windings, and one or more of loads in series connection, the full-wave rectifier connected to an output of the power supply and performing full-wave rectification for the alternating-current of the power supply. Currents flowing in the respective series circuits are balanced based on an electromagnetic force generated in one or more of the windings.

Abstract: An AC conversion circuit includes a main transformer having a primary winding and a secondary winding to electrically insulate the AC power source side and the discharge tube side from each other, an IC1 arranged on the AC power source side, a plurality of switching elements arranged on the AC power source side and driven by the IC1, to pass a current through the primary winding of the main transformer based on the DC power, an IC2 arranged on the discharge tube side, to generate a pair of rectangular-wave signals for conducting PWM control on a current passing through the discharge tube and having the same pulse width with a duty ratio of less than 50% and a phase difference of about 180 degrees, and one or more signal transfer insulated elements to send the pair of rectangular-wave signals from the IC2 to the IC1.

Abstract: A discharge lamp lighting apparatus includes switching elements to pass a current to a primary winding of a transformer and a capacitor, an oscillator to generate a triangular signal, an error amplifier to amplify an error voltage of a voltage corresponding to a current passed through a discharge lamp and receive a burst dimming signal that is a pulse signal to intermittently supply power to the discharge lamp, comparators to compare the error voltage with the triangular signal and generate PWM control signals that turn on/off the switching elements, respectively, a clamp circuit to clamp an output from the error amplifier so that the output from the error amplifier may not drop below a lower limit value of the triangular signal during an OFF period of the burst dimming signal, and breaking circuits to block the PWM control signals during the OFF period of the burst dimming signal.

Abstract: An LCD apparatus includes an LCD panel to display an image and an LED backlight to illuminate the LCD panel from behind. The LCD panel has first sections divided in a vertical direction and second sections divided in a horizontal direction. The LED backlight includes an LED light source and an edge-type light guide. The LED light source includes LEDs that are arranged along at least one of upper and lower sides of the light guide and are allocated to the second sections, respectively. A brightness of an image displayed in a given second section is used to control a light quantity of the corresponding LED. Each LED radially emits light so that light beams from adjacent ones of the LEDs intersect each other.

Abstract: The present invention includes: a power supply unit 10 outputting an alternating current; and multiple series circuits each of which is connected to an output of the power supply unit 10 and includes at least one winding N1, S1, at least one rectifying element D1, D2, and at least one load LED1a, 2a, which are connected in series. Currents flowing through the multiple series circuits are balanced based on an electromagnetic force generated at the at least one winding N1, S1.

Abstract: A current balancing apparatus includes a first transformer having a first primary winding and a first secondary winding electromagnetically coupled with the first primary winding, the first primary winding having a first end connected to a first load that passes a first current; a second transformer having a second primary winding and a second secondary winding electromagnetically coupled with the second primary winding, the second primary winding having a first end connected to a second load that passes a second current having an AC component substantially having a 180-degree phase difference with respect to the first current; and a series circuit including the first secondary winding, the second secondary winding, and a current smoother, to balance the first current and second current with each other.

Abstract: A discharge-lamp lighting apparatus includes series circuits connected to each end of a DC power source, a transformer, FETs Qp1, Qn1, Qp2, and Qn2, and a drive circuit. The drive circuit includes transistors Q1 and Q3 to discharge gate-source capacitances of the Qp1 and Qp2, resistance elements to determine gate potentials of the transistors Q1 and Q3 when the transistors Q1 and Q3 are turned on, transistors Q2 and Q4 to charge the gate-source capacitances of the Qp1 and Qp2, constant current circuits, and switches connected in series with the series circuits of the constant current circuits and resistance elements, respectively, to turn on/off the constant current circuits.

Abstract: It is possible to reliably prevent two switching elements comprising a half-bridge circuit from turning ON simultaneously even when two pulse signals allowing both the two switching elements to turn ON are input thereto. A first drive signal is allowed to be output from a first output terminal 4 to a P-type MOSFET 10 based on a first pulse signal and a second pulse signal, and a second drive signal is allowed to be output from a second output terminal 5 to an N-type MOSFET 11 that operates as a second switching element based on the first pulse signal and the second pulse signal, and a protecting circuit 20 is configured to allow at least one of the P-type MOSFET 10 and the N-type MOSFET 11 to turn OFF.

Abstract: A DC/AC converter includes: a resonant circuit including a transformer having a primary winding and a secondary winding and at least one capacitor, in which the capacitor is connected to at least one of the primary winding and secondary winding of the transformer, and an output terminal to which the load is to be connected is provided on the secondary winding side; a switching circuit connected to both ends of a direct current power supply and having a bridge configuration composed of switching elements for flowing a current through the primary winding of the transformer and the capacitor in the resonant circuit; and a control circuit that turns on/off the switching elements by a pair of drive signals, and flows a current through the load bidirectionally, thereby performs a PWM control for the current flowing through the load, wherein the control circuit includes step drive circuits which turn on the switching elements in steps, and the step drive circuits are provided so as to individually correspond to the

Abstract: A DC/AC converter includes a resonant circuit having a first capacitor connected to at least one of a primary winding and a secondary winding of a transformer and an output end connected to a load, the resonant circuit receiving an alternating signal having a predetermined frequency and amplitude to pass a current, a variable impedance element connected in parallel with a part of the output end of the resonant circuit, the variable impedance element changing the impedance value thereof according to a current passing through the load, and a controller to control the current passing through the load to a predetermined value by changing the resonant frequency of the resonant circuit according to the changed impedance value of the variable impedance element.

Abstract: An apparatus for lighting LEDs includes an LED group load having the LEDs, a converter to generate a voltage applied to the LED group load, a current controller to control a current of the LED group load, a voltage controller to control an output voltage provided by the converter, a time division circuit to intermittently pass a current through the LED group load, and a selector. The selector, during a period in which the time division circuit passes a current through the LED group load, selects the current controller to control a current of the LED group load and thereby control an output voltage provided by the converter, and during a period in which the time division circuit passes no current through the LED group load, selects the voltage controller to control an output voltage provided by the converter.

Abstract: A power conversion apparatus includes a first DC converter to convert an AC voltage from an AC power source into a DC voltage and correct a power factor, a light emitting load to emit light under a predetermined DC voltage, a second DC converter to electrically insulate the first DC converter and the light emitting load from each other, convert the DC voltage from the first DC converter into the predetermined DC voltage, and supply the predetermined DC voltage to the light emitting load, a plurality of loads to operate under low DC voltages, and a third DC converter to electrically insulate the first DC converter and the plurality of loads from each other, convert the DC voltage from the first DC converter into low DC voltages, and supply the low DC voltages to the plurality of loads.

Abstract: The present invention includes a first DC converter converting AC voltage, into DC voltage while correcting a power factor, and a second DC converter electrically isolating the first DC converter from an LED group load, and converting the DC voltage, into a predetermined DC voltage and supply the resultant voltage to the LED group load. The second DC converter includes a current detection circuit disposed on the secondary side, and detecting current flowing into the LED group load, an error amplifier amplifying an error between a detected current value detected and a reference current value, a signal transmission isolation element transmitting a control signal based on an output signal from the error amplifier, to the primary side, and a switching element transferring power to the secondary side through the transformer by being turned on/off according to the control signal.

Abstract: A discharge lamp lighting apparatus includes a triangular signal oscillator, a first control part to compare the triangular signal with an error voltage between a reference voltage and a voltage corresponding to a first current passed through a secondary winding of a transformer and generate a first PWM control signal for turning on/off switching elements Qp1 and Qn1 with a phase difference of about 180 degrees and a pulse width corresponding to the first current, and a second control part to compare the triangular signal with an error voltage between a reference voltage and a voltage corresponding to a second current passed through a secondary winding S2 of a transformer T2 and turn on/off switching elements Qp2 and Qn2 in synchronization with the first PWM control signal with a phase difference of about 180 degrees and a pulse width corresponding to the second current.

Abstract: A discharge lamp lighting apparatus includes a first inverter, a second inverter to output a voltage whose phase is opposite to that of a voltage provided by the first inverter, a discharge lamp connected between a first output terminal of the first inverter and a first output terminal of the second inverter, a first current detection circuit arranged between a second output terminal of the first inverter and a common potential and having a first current detection element and a second current detection element that are connected in series, a second current detection circuit arranged between a second output terminal of the second inverter and the common potential and having a third current detection element and a fourth current detection element that are connected in series, and a protection circuit to detect a current abnormality according to a composite signal of outputs of the second and fourth current detection elements and stop the operation of the first and second inverters.

Abstract: (1) An oscillator generates a triangular wave signal whose inclination for charging a capacitor and inclination for discharging the same are the same and which is used to turn on/off FETs Qp1 and Qn1, (2) a signal generation part generates first drive signal in a period shorter than a half period of the triangular wave signal to drive the Qp1, and generates a second drive signal having a pulse width substantially equal to that of the first drive signal and a phase difference of about 180 degrees with respect to the first drive signal, to drive the Qn1 and provide a current to the discharge tube in a direction opposite to the current driven by the first drive signal, and (3) a pulse current generation circuit converts a synchronization pulse voltage signal into a pulse current that alternates between positive and negative current values of the same absolute value at a duty of about 50% and superimposes the pulse current on the triangular wave signal to drive the first drive signal and the second drive signal.

Abstract: A discharge lamp lighting apparatus is mounted on a single circuit board. The apparatus converts a direct current into an alternating current, applies voltages of opposite phases to both ends of a discharge lamp. The apparatus includes two resonant circuits. Each of the resonant circuits includes a transformer having a primary winding and a secondary winding, a resonant reactor, and resonant capacitors. Output terminals of the two resonant circuits are connected to the ends of the discharge lamp, to apply the voltages of opposite phases to the ends of the discharge lamp, respectively. Resonant characteristics of the two resonant circuits are equalized with each other by determining values of the resonant reactors of the two resonant circuits according to values of stray capacitances determined by the lengths of high-voltage output lines extended from the two resonant circuits to the ends of the discharge lamp.

Abstract: A synchronous operating system for operating a plurality of discharge tube lighting apparatuses at the same frequency and same phase includes (1) a resonant circuit including a capacitor C3 connected to at least one of primary and secondary windings, an output thereof being connected to a discharge tube, (2) switching elements Qp1 and Qn1 connected to both ends of a DC power source, (3) an oscillator to generate a triangular wave signal whose inclination for charging a capacitor C2 and inclination for discharging the same are the same, (4) a signal generation part to generate, in a period shorter than a half period of the triangular wave signal, a first drive signal having a pulse width corresponding to a current passing through the discharge tube, and (5) a signal generation part to generate a second drive signal having a pulse width substantially equal to that of the first drive signal and a phase difference of about 180 degrees with respect to the first drive signal.