Sanken Electric Co., Ltd.

Mizuki Utsuno

Ryuichi Furukoshi

Mitsutomo Yoshinaga

Makoto Sato

Toru Ashikaga

Kazushige Hirata

Hiroyuki Chikashige

Hideto Sugiura

Eri Tamegai

Tomohiro Miyata

Sadahiro Yamazaki

Shigenori Ishii

Toyotomo Morita

Yoshikazu Takahashi

Masayuki Watanabe

Hiromi Koiwai

A pseudo-resonant switching power source device is provided which comprises a primary windingof a transformerand a main MOS-FETconnected in series to a DC power source, a voltage-resonant capacitorconnected in parallel to main MOS-FET, a rectification smootherconnected to a secondary windingof transformerand having a rectification MOS-FETand a smoothing capacitor, a synchronized rectification controllerfor turning rectification MOS-FETon after turning-off of main MOS-FETand turning rectification MOS-FEToff before turning-on of main MOS-FET, a pulse width elongation circuitfor extending on-pulse width of rectification MOS-FET, and a main control circuitfor producing main drive signals to turn main MOS-FEToff and on with operation frequency responsive to on-pulse width of rectification MOS-FETextended by pulse width elongation circuitto vary operation frequency of main MOS-FETso as to restrain noise by high frequency components in main drive signals from main control circuit

Switching power source device

A DC power source apparatus converts a DC input voltage into high-frequency power by turning on/off a switching element connected to a primary winding of a transformer and converts the high-frequency power transmitted to a secondary winding of the transformer into a DC output voltage. The primary and secondary windings of the transformer include a core winding set having a primary winding Pwound around a leg of a core defining a closed magnetic path and a secondary winding externally wound around the primary winding and another core winding set having a primary winding Pwound around a leg of the core and a secondary winding externally wound around the primary winding. The primary winding of each of the two core winding sets has a plurality of winding layers among which a lowermost one that is closest to the core is connected to the switching element.

DC power source apparatus

Since there exists a draw-out portion of a triple insulated wire in a winding structure of a transformer in which the triple insulated wire is used as a secondary winding, the thickness of the transformer is increased by an amount corresponding to the wire diameter of the draw-out portion. Further, when reduction of the thickness of the transformer is prioritized, the secondary winding can be provided only on one side, making it impossible to achieve the sandwich structure. Thus, the coupling between the primary and secondary windings has been sacrificed. An inductance part provided with a magnetic core, two or more sheet coils, and a winding includes: a bobbin constituted by at least two or more sheet coils; and a winding formed by winding a triple insulated wire between the two or more sheet coils constituting the bobbin. A triple insulated wire draw-out portion on the center side of the winding is drawn out to one outer surface side of the bobbin.

Inductance part

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 input voltage is applied by an NMOS transistor () driven by an oscillation circuit () to a primary winding () of a transformer () intermittently. A voltage induced in a secondary winding () is rectified and smoothed by an output circuit () to be an output voltage. In a normal mode where no standby signal is supplied, the oscillation circuit () controls the NMOS transistor () so that the output voltage is stabilized at a predetermined first value. When a standby signal is supplied, a detection circuit () detects the standby signal and transmits the detection to a starting circuit (). The starting circuit () starts the oscillation circuit () when a voltage of a capacitor () reaches an upper limit, and stops the oscillation circuit () when this voltage lowers below a lower limit. This upper limit is lower than an upper limit at which the starting circuit () starts the oscillation circuit () in the normal mode.

Power source apparatus

A DC power source apparatus has a DC power source for supplying a DC voltage, a transformer, and a switching element connected to a primary winding of the transformer. The switching element carries out ON/OFF operations to convert the DC voltage from the DC power source into high-frequency power, which is transferred to a secondary winding of the transformer and is converted into a DC output voltage. The primary winding of the transformer consists of a first primary winding made of a plurality of winding layers and a second primary winding made of a plurality of winding layers. The first and second primary windings are connected in parallel. The first primary winding is arranged on an inner side of the secondary winding, and the second primary winding is arranged on an outer side of the secondary winding. A terminal of a winding layer farthest from the secondary winding among the winding layers of each of the first and second primary windings is connected to the switching element.

A switching power supply has a bottom detection circuit ( ), which judges whether or not a bottom has been reached, based on a voltage of a capacitor (C ) that determines an off time of a switching element (Q ) that generates a voltage at the secondary side of a transformer ( ) and, in the case in which the judgment is made that a bottom has not occurred, a charging voltage for the capacitor (C ) is switched to a high-potential side.

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Niiza, Japan

Mizuki Utsuno