Sanken Electric Co., Ltd.

Toru Ashikaga

Kengo Kimura

Kazushige Hirata

Hiroshi Usui

Toshihiro Nakano

Mizuki Utsuno

Jaehee Cho

Toyotomo Morita

An alternating current input voltage detection circuit comprises: a first voltage waveform detection circuit that detects a voltage waveform of one alternating current input terminal of the diode rectification circuit, based on a reference potential of the device; a second voltage waveform detection circuit that detects a voltage waveform of the other alternating current input terminal of the diode rectification circuit, based on the reference potential of the device, and a voltage waveform generation circuit that: calculates a first detection voltage waveform, which is output from the first voltage waveform detection circuit, and a second detection voltage waveform, which is output from the second voltage waveform detection circuit; generates a voltage waveform signal, in which waveform distortions generated in the first detection voltage waveform and the second detection voltage waveform are eliminated; and outputs the voltage waveform signal as the voltage detection signal.

Alternating current input voltage detection circuit

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 switching elements.

DC/AC converter

A discharge lamp lighting device is provided to comprise tube current detecting circuitstofor outputting detection signals Vto Vof tube currents Ito Iflowing through each discharge lamptofrom an inverterconnected to DC power sourcevia a plurality of transformersto, a maximum detectorfor detecting a maximum value Vof detected signals Vto Vfrom current detectorto, a minimum detectorfor detecting a minimum value Vof detected signals Vto Vfrom current detectorto, a comparison circuitfor computing one or plural values of sum, difference, product and quotient between maximum value Vfrom maximum detectorand minimum value Vfrom minimum detectorto generate a cease signal Vwhen the computed value exceeds a given value, and a control circuitfor halting operation of inverterwhen comparison circuitgenerates cease signal V. The device can reliably detect arc discharge resulted from electric connection failure in discharge lamp or lamps by the computed values from comparison circuitto positively protect discharge lamps from overheating by arc discharge at a bad connection location.

Discharge lamp lighting device

A cold cathode fluorescent lamp inverter apparatus includes a series circuit connected to a DC power source and including first and second switching elements, a series circuit connected between a connection point of the first and second switching elements and the DC power source and including a primary winding of a transformer, a reactor, and a capacitor, a cold cathode fluorescent lamp connected to a secondary winding of the transformer, a current detector connected to the cold cathode fluorescent lamp and to the secondary winding, to detect a value of a current passed through the cold cathode fluorescent lamp, and a controller to turn on/off the first and second switching elements alternately with each other according to the detected current value. The current detector detects a ripple component in the DC power source, and corrects the current of the cold cathode fluorescent lamp according to the detected ripple component.

Cold cathode fluorescent lamp inverter apparatus

A luminescent lamp lighting device includes a plurality of switch circuitseach connected to each of luminescent lampsin series under one-to-one correspondence, a plurality of optical coupling circuitseach connected to each of the switch circuits under one-to-one correspondence to turn on/off the switch circuits and a plurality of current detecting circuitseach connected to each of the luminescent lamps in series under one-to-one correspondence to detect currents flowing the luminescent lamps. The device determines whether the luminescent lamps are turned on or not, based on the currents detected by the current detecting circuits and controls the optical coupling circuits based on the determination result so as to allow all of the luminescent lamps but a luminescent lamp requiring a highest lighting voltage to be turned on in order of low lighting voltage, next allow the lighted luminescent lamps to be turned lighted off, and allow all of the remaining luminescent lamps to be turned on again after turning on the luminescent lamp requiring the highest lighting voltage.

Luminescent lamp lighting device

An alternating current power supply device is provided with switch elements Q, Qfor converting direct current power from a direct current power supply Vin into alternating current power; a transformer Tfor converting the voltage of the alternating current power converted by the switch elements into other voltage; a loadconnected to an output terminal of the transformer; a first detecting circuitfor detecting a first electric signal indicating power to be supplied to the load; a second detecting circuitfor detecting a second electric signal indicating the voltage of the direct current power supply; a feedback circuitfor generating a feedback signal based on the first electric signal detected by the first detecting circuit and the second electric signal detected by the second detecting circuit; and a control circuitfor generating a control signal based on the feedback signal from the feedback circuit and controlling on/off of the switch elements by the control signal so that power to be supplied to the load is at a prescribed value.

Alternating current power supply device and integrated circuit for alternating current power supply device

A time division signal (S) for instructing a lit period and an unlit period of a discharge tube () is input to an error amplifier () of an integration circuit (). The integration circuit () charges and discharges a capacitor () in accordance with the time division signal (S). By utilizing this operation, a control circuit () adjusts a current flowing through the discharge tube () to light and extinguish the discharge tube ().

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Niiza, Japan

Toru Ashikaga