Toko, Inc.

Toko Kabushiki Kaisha

Yutaka Electric Mfg. Co., Ltd.

Nemic Lambda Kabushiki Kaisha

Densetsu Corporation

Tokyo Corporation

Koji Arakawa

Shigeru Kameyama

Hitoshi Yoshioka

Kazushi Watanabe

Isami Norigoe

Masanori Ishii

Teruo Tamada

An AC-DC converter is disclosed which is so designed as to realize an improved power factor and thereby minimize generation of voltage distortion and higher harmonies in power supply line, without making the circuit arrangement complex and bulky. A step-down DC-DC converter is connected to an output side rectifier, and the arrangement is made such that the output current of the rectifier is permitted to flow only during a time period when the output voltage of the rectifier is higher than the voltage at an output capacitor of the DC-DC converter.

AC-DC converter

An AC-DC converter of a type having an improved power factor having an arrangement that enlargements of loads to be borne by circuit components due to AC input voltage is prevented so that the size and cost of the AC-DC converter are reduced. A constant-current circuit is, in parallel, connected to a voltage dividing point of charge voltage of an output capacitor to be connected to an input terminal of an error amplifier of a booster converter circuit and realized by a plurality of resistors so that control of a constant-current value of the constant-current circuit is performed with the rectified output from the rectifying circuit. As a result, the loads to be borne by the circuit components of the AC-DC converter can be made constant regardless of the supplied AC voltage level so that the size and cost of the AC-DC converter are reduced.

AC-DC converter having improved power factor to control feedback signal

A power-factor improved AC-DC converter has a rectifier circuit, a booster converter circuit and a DC-DC converter circuit. A winding on a converter transformer of the DC-DC converter circuit supplies power to both a DC-DC converter control circuit and a booster converter control circuit. In starting up the AC-DC converter, the DC-DC converter circuit is started first, followed by start of operation of the booster converter circuit. With this arrangement, power-factor improved AC-DC converter can be realized with minimum increase in the size and production cost, and the start-up characteristic is improved to avoid failure of start up of the AC-DC converter.

The present invention provides an AC-DC converter in which an application range of an AC input voltage can be extended, keeping a voltage in a circuit from rising at a light load. In an AC-DC converter having a rectifier 3, a boost chopper 4 and a DC-DC converter 5, a PWM circuit 6, an one-shot multivibrator 7, a pulse synthesizer 8 and a comparator 9 are further arranged. The pulse synthesizer 8 generates a second pulse signal having a pulse width being narrower by a pulse width of the delay pulse V.sub.pD than that of the first pulse signal V.sub.pa by means of the first pulse signal V.sub.pa which the PWM circuit 6 output s and a delay pulse V.sub.pD generating in said one-shot multivibrator 7. The comparator 9 compares a voltage V.sub.C boosted up by the boost chopper 4 with a reference voltage V.sub.REF to stop generating the delay pulse when voltage V.sub.C drops below the reference voltage V.sub.REF .

This invention provides an AC-DC converter in which the shape and the cost do not increase by a measure for a harmonic distortion in the power factor improved AC-DC converter generating little harmonic distortion. In the AC-DC converter, a control input terminal of a switching transistor of an active filter is connected to an output terminal of a flip-flop, a set input terminal of which is connected to a DC-DC converter to receive a synchronizing pulse signal therefrom. A reset input terminal of the flip-flop is connected to an output terminal of a comparator to receive an OFF-timing signal from the comparator. The comparator determines OFF-timing of the switching transistor by comparing a level voltage with an outout voltage from a saw-tooth wave generating circuit. Thereby since it is not required that an active filter has a multiplier and an an oscillating circuit, its circuit construction is simple and the AC-DC converter in small size and at low cost is realized.

AC-DC converter having saw-tooth wave generating circuit in active filter

An object of the present invention is to provide a structure for a choke coil which facilitates making choke coils more compact, thinner and easier to manufacture. The structure uses a band-shaped conductor, the terminal portions at both ends are fixed in a terminal fixing plate provided to one end of the winding portion of a bobbin.

Choke coil

A DC-DC convertor includes a transformer having a primary winding adapted to be connected in series with a DC power source and a secondary winding, a rectifier and smoothing circuit, a main switching device, adapted to be connected in series with the DC power source, for connecting the rectifier and smoothing circuit to the secondary winding of the transformer when the main switching device is in an on-state, an auxiliary switching circuit connected in parallel with the main switching device, and a signal generating circuit for providing a first control signal to the main switching device and a second control signal to the auxiliary switching circuit. The auxiliary switching circuit includes a first capacitor connected in parallel with a second capacitor that is connected in series with an auxiliary switching device. The signal generating circuit controls on/off operation of the main switching device and the auxiliary switching device such that both the main switching device and the auxiliary switching device are in an off state simultaneously in a manner wherein the main switching device turns on after a first rest period has elapsed after the auxiliary switching device turns off and the auxiliary switching device turns on after a second rest period has elapsed after the main switching device turns off.

DC-DC converter

A DC-DC converter includes a transformer and a switching element. The primary winding of the transformer and the switching element are connecting in series with a DC power source. A DC output is extracted via a rectifier circuit connected to a secondary winding of the transformer. A capacitor is connected in parallel to the switching element, and a saturable reactor is connected between the secondary winding of the transformer and the rectifier.

In a battery charging device, terminals for supplying a charging current to a battery to be charged are provided on one side wall of the device body, and a closure member is provided to be movable like a drawer. When the closure member is drawn out, at least one opening is defined between the closure member and said one side wall so that the battery can be inserted and held therein to be charged.

Battery charging device

A ceramic filter comprising a plurality of three-terminal, dual-mode ceramic filter elements which are connected with each other through a capacitive coupling circuit which is adapted to increase the input/output impedance of the ceramic filter.

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Tsurugashima, Japan

Koji Arakawa