Transformerless power-supply unit for supplying a low DC voltage

Claim 2

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first reference voltage generation circuit for generating a first reference voltage based on an output voltage of said rectifier circuit, said first reference voltage generation circuit including a Zener diode for setting said first reference voltage; a second reference voltage generation circuit for generating a second reference voltage based on said output voltage and larger than said first reference voltage, said second reference voltage generation circuit including a Zener diode for setting said second reference voltage; a control circuit for turning said switching means on when said output voltage is in a range between said first reference voltage and said second reference voltage and turning said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 3

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first phase-angle voltage generation circuit for generating a first phase-angle voltage which is based on an output voltage of said rectifier circuit and corresponding to a first phase-angle of said A.C. power source, said first phase-angle being a non-zero phase-angle; a second phase-angle voltage generation circuit for generating a second phase-angle voltage which is based on said output voltage and corresponding to a second phase-angle of said A.C. power source larger than said first phase-angle; a control circuit for turning said switching means on when said output voltage is in a range between said first phase-angle voltage and said second phase-angle voltage and turning said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 4

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first phase-angle voltage generation circuit for generating a first phase-angle voltage which is based on an output voltage of said rectifier circuit and corresponding to a first phase-angle of said A.C. power source, said first phase-angle being a non-zero phase-angle; a second phase-angle voltage generation circuit for generating a second phase-angle voltage which is based on said output voltage and corresponding to a second phase-angle of said A.C. power source larger than said first phase-angle; a control circuit for turning said switching means on when said output voltage is in a range between said first phase-angle voltage and said second phase-angle voltage and turning said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 5

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first reference voltage generation circuit for generating a first reference voltage based on an output voltage of said rectifier circuit; a second reference voltage generation circuit for generating a second reference voltage based on said output voltage and larger than said first reference voltage; a first phase-angle voltage generation circuit for generating a first phase-angle voltage which is based on said output voltage and corresponding to a first phase-angle of said A.C. power source; a second phase-angle voltage generation circuit for generating a second phase-angle voltage which is based on said output voltage and corresponding to a second phase-angle of said A.C. power source and which is larger than said first phase-angle; a first mixing circuit for generating a first mixed voltage which is obtained by mixing said first reference voltage with said first phase-angle voltage by means of a first mixing ratio; a second mixing circuit for generating a second mixed voltage which is obtained by mixing said second reference voltage with said second phase-angle voltage by means of a second mixing ratio; a control circuit for turning said switching means on when said output voltage is in a range between said first mixed voltage and said second mixed voltage and making said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 6

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first reference voltage generation circuit for generating a first reference voltage based on an output voltage of said rectifier circuit; a second reference voltage generation circuit for generating a second reference voltage based on said output voltage and larger than said first reference voltage; a first phase-angle voltage generation circuit for generating a first phase-angle voltage which is based on said output voltage and corresponding to a first phase-angle of said A.C. power source; a second phase-angle voltage generation circuit for generating a second phase-angle voltage which is based on said output voltage and corresponding to a second phase-angle of said A.C. power source and which is larger than said first phase-angle; a first mixing circuit for generating a first mixed voltage which is obtained by mixing said first reference voltage with said first phase-angle voltage by means of a first mixing ratio; a second mixing circuit for generating a second mixed voltage which is obtained by mixing said second reference voltage with said second phase-angle voltage by means of a second mixing ratio; a control circuit for turning said switching means on when said output voltage is in a range between said first mixed voltage and said second mixed voltage and making said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 7

A power-supply unit in accordance with claim 3 further comprising: a current limiting circuit connected in series to said switching means.

Claim 8

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first phase-angle voltage generation circuit for generating a first phase-angle voltage which is based on an output voltage of said rectifier circuit and corresponding to a phase-angle of said A.C. power source, said first phase-angle remaining constant and independent of variations in said A.C. power source; a second phase-angle voltage generation circuit for generating a second phase-angle voltage which is based on said output voltage and corresponding to a second phase-angle of said A.C. power source larger than said first phase-angle, said second phase-angle remaining constant and independent of variations in said A.C. power source; a control circuit for making said switching means on when said output voltage is in a range between said first phase-angle voltage and said second phase-angle voltage and turning said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 9

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first phase-angle voltage generation circuit for generating a first phase-angle voltage which is based on an output voltage of said rectifier circuit and corresponding to a phase-angle of said A.C. power source, said first phase-angle remaining constant and independent of variations in said A.C. power source; a second phase-angle voltage generation circuit for generating a second phase-angle voltage which is based on said output voltage and corresponding to a second phase-angle of said A.C. power source larger than said first phase-angle, said second phase-angle remaining constant and independent of variations in said A.C. power source; a control circuit for making said switching means on when said output voltage is in a range between said first phase-angle voltage and said second phase-angle voltage and turning said switching means off when said output voltage is outside said range; and a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range.

Claim 10

A power-supply unit according to claims 2 or 5, wherein said first phase-angle voltage generation circuit includes a first resistor connected in series with a second resistor and capacitor across said A.C. power source, said second resistor and capacitor are connected in parallel.

Claim 11

A power-supply unit according to claims 2 or 5, wherein said second phase-angle voltage generation circuit includes a first resistor connected in series with a second resistor and capacitor across said A.C. power source, said second resistor and capacitor are connected in parallel.

Claim 12

A power-supply unit according to claims 2 or 5, wherein said control circuit includes: first comparator means for comparing said first phase-angle voltage with a reference voltage; second comparator means for comparing said second phase-angle voltage with said reference voltage; a diode having an anode and a cathode, said cathode connected to an output of said first comparator means; a resistor having a first and second end, said first end connected to an output of said second comparator means, said second end connected to said anode; and a transistor having an emitter, a collector, and a base, said base connected to said anode, said emitter connected to said A.C. power source, and said collector connected to said switching means.

Claim 13

A power-supply unit in accordance with any one of claims 1, 2 and 5 further comprising: a current limiting circuit connected in series to said switching means.

Claim 14

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first voltage generation circuit for generating a first voltage based on an output voltage of said rectifier circuit, said first voltage being a non-zero voltage; a second voltage generation circuit for generating a second voltage based on said output voltage and larger than said first voltage; a control circuit for turning said switching means on when said output voltage is in a range between said first voltage and said second voltage and turning said switching means off when said output voltage is outside said range; a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range; and wherein said first voltage generation circuit includes a first Zener diode, a resistor and a second Zener diode connected in series across said A.C. power source.

Claim 15

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first voltage generation circuit for generating a first voltage based on an output voltage of said rectifier circuit, said first voltage being a non-zero voltage; a second voltage generation circuit for generating a second voltage based on said output voltage and larger than said first voltage; a control circuit for turning said switching means on when said output voltage is in a range between said first voltage and said second voltage and turning said switching means off when said output voltage is outside said range; a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range; and wherein said first voltage generation circuit includes a first Zener diode, a resistor and a second Zener diode connected in series across said A.C. power source.

Claim 16

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first voltage generation circuit for generating a first voltage based on an output voltage of said rectifier circuit, said first voltage being a non-zero voltage; a second voltage generation circuit for generating a second voltage based on said output voltage and larger than said first voltage; a control circuit for turning said switching means on when said output voltage is in a range between said first voltage and said second voltage and turning said switching means off when said output voltage is outside said range; a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range; and wherein said second voltage generation circuit includes: a transistor having an emitter, a base and a collector; a resistor connected to said base; and a Zener diode connected to said collector.

Claim 17

A power-supply unit comprising: a rectifier circuit connected to an A.C. power source; switching means for opening/closing an electric line which supplies a load circuit with electric power from said A.C. power source via said rectifier circuit; a first voltage generation circuit for generating a first voltage based on an output voltage of said rectifier circuit, said first voltage being a non-zero voltage; a second voltage generation circuit for generating a second voltage based on said output voltage and larger than said first voltage; a control circuit for turning said switching means on when said output voltage is in a range between said first voltage and said second voltage and turning said switching means off when said output voltage is outside said range; a capacitor which is charged with electricity by said output voltage when said output voltage is in said range and supplies said load circuit with electric power when said output voltage is outside said range; and wherein said second voltage generation circuit includes: a transistor having an emitter, a base and a collector; a resistor connected to said base; and a Zener diode connected to said collector.