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AssigneesFuji Electric Co., Ltd., Makita Corporation, Okada Electric Co, Ltd.
InventorsMasami Furuta, Takao Iwatsuki, Masatoshi Sugiura, Toshio Matsumoto, Hideki Watanabe, Hideiki Niwa
Estimating the term…
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.
A battery charger with a charging current controller comprising:
Dependencies are inferred from the claim text.
No related US applications are recorded in the indexed filing history.
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Circuit arrangements for charging or discharging batteries or for supplying loads from batteries: for charging batteries from AC mains by converters
Details of circuit arrangements for charging or discharging batteries or supplying loads from batteries: charging or discharging characterised by…
Power supply and charging
Term ended 24 Apr 2011 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
The present invention relates to a battery charger for charging a battery pack of an electric appliance such as an electric cleaner and a power driven tool, and more particularly to an improvement in a circuit configuration of the battery charger.
2. Description of the Prior Art
FIG. 1 is a circuit configuration of a battery charger according to the present invention;
FIG. 2 is a block diagram showing a circuit configuration of an IC for controlling a primary side of the circuit shown in FIG. 1;
FIG. 3 is a timing chart showing wave configurations of various signals in the circuit shown in FIG. 1 during a starting period and a normal operation period;
Referring to FIG. 1, there is shown a circuit configuration of a battery charger according to the present invention. In FIG. 1, the same elements as shown in FIG. 6 are labeled by the same numerals, and an explanation for these elements is omitted.
A primary DC power circuit 1 comprises of a filtration circuit 1c for eliminating noise, a diode bridge circuit 1d and a smoothing capacitor C2. A noise elimination circuit 10 including a resistor R7, a capacitor C3 and a diode D2 is connected across a primary main coil Ta of a Transformer T' for drop of voltage. A field-effect transistor FET having an insulated gate and operating as a chopper is connected in series with a shunt resistor R8 between the primary coil Ta and the earth. The transistor FET is intermittently turned at a predetermined frequency by a gate control signal G1 which has a variable duty cycle and is derived from a primary control circuit 20 as will be hereinafter explained.
A secondary DC power circuit 2 comprises of rectifying diodes D3 and D4, a current limiting coil L and a smoothing capacitor C3. A DC stabilization power circuit 30 for supplying a line voltage Vcc (5 V) to a secondary control circuit 4 and a current detector circuit 3, etc. is connected with a secondary shunt coil Tb of the transformer T'. The DC stabilization power circuit 30 includes a rectifying diode D5, a three-terminal regulator IC and capacitors C4 and C5. A DC power circuit 40 for supplying the line voltage Vcc (5 V) for the primary control circuit 20 etc. is connected with a primary shunt coil Tc of the transformer T'. The DC power circuit 40 includes a rectifying diode D6 and a smoothing capacitor C6.