Fuji Electric Co., Ltd.

Matsushita Electric Industrial Co., Ltd.

Makita Corporation

Okada Electric Co, Ltd.

Masami Furuta

Toshio Matsumoto

Masatoshi Sugiura

Hiroyuki Ota

Hideki Watanabe

Syuji Kamada

Takao Iwatsuki

Hideiki Niwa

A speed-up circuit 10 is connected to a detection line 6 for feeding back the high voltage detection value of a high voltage detection circuit 5 to a high voltage stabilizing circuit 1. When a power supply switch is turned on, since a PNP transistor 12 of the speed-up circuit 10 is turned on, a resistor 11 is connected to the detection line 6, so that the high voltage detection value is reduced forcedly. Accordingly, the high voltage stabilizing circuit 1 increases the peak value of a flyback pulse generated by a resonance-type power supply circuit 2 to output higher high voltage thereby to shorten the rising time of the high voltage output supplied to the anode of a CRT. After the lapse of the predetermined time from the turning-on of the power supply switch, since the terminal voltage of a capacitor 13 having been charged through a resistor 14 exceeds almost the voltage at a point A, the PNP transistor 12 is turned off, so that the resistor 11 is separeted from the detection line. Accordingly, the responsibility of the flyback pulse is prevented from being degraded at the time of the abrupt change of the load of the CRT.

High voltage power supply circuit

A battery charger includes a transformer having a primary coil and a secondary coil, a switch for duty control of a current flowing through the primary coil of the transformer, a detector for detecting a value of a current flowing through the secondary coil of the transformer, and a secondary controller for receiving the detected value from the detector and for outputting a charge control signal. The pulse of the charge control signal is modulated in accordance with the detected value by the detector. The battery charger further includes a light emitter controlled by the charge control signal for flickering, a phototransistor turning on and off according to the flickering of the light emitter, and a primary controller for converting the ratio of the time during on of the phototransistor to the time during off of the phototransistor into an analog value, and for outputting to the switch a pulse signal which is modulated to have a duty cycle corresponding to the analog value so as to control a duty cycle of the switch.

Battery charger with charging current controller

A DC voltage converter comprising: a switching transistor for establishing a load current circuit which connects a DC power source to a load to supply a load current to the load; a differentiating circuit connected in series to the load current circuit for producing a voltage drop corresponding to a differentiated value of the load current; an integrating capacitor connected in parallel with the load via an output terminal for outputting as an output voltage to be supplied to the load a voltage corresponding to an integrated value of a current flowing through the capacitor; a control width setting circuit for setting a width defined by upper and lower limits for controlling the output voltage in accordance with the voltage drop derived from the differentiating circuit; a ripple detection circuit receiving the output voltage from the capacitor and for detecting a ripple caused by an 'ON-OFF' operation of the switching transistor; an output-reference-level setting circuit for setting a reference voltage of the output voltage; and a switching control circuit receiving a width signal corresponding to the width and a ripple signal corresponding to the ripple for forming a switching instruction to the switching transistor, so that a variation in the output voltage is limited within the width.

DC voltage converter

Growing community of inventors

Kawasaki, Japan

Masami Furuta