Power supply apparatus and printing apparatus
AssigneeCanon Kabushiki Kaisha
InventorTakashi Kasahara
Life of this patent
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Abstract
A power supply apparatus capable of switching an output voltage Vout based on an external control signal includes a control unit configured to perform control to stop an output from the power supply apparatus in a case where a voltage applied to a Vcc terminal is higher than a predetermined voltage Vovp. The Vcc terminal is connected to a primary-side auxiliary winding of a transformer via a regulator and the control unit operates based on power supplied to the Vcc terminal in normal operation. A base of an NPN transistor included in the regulator is connected to a ground via a first resistance R1 and a first zener diode ZD1. A second resistance R2 is provided between the base and a collector of the NPN transistor.
Claims8
A power supply apparatus capable of switching an output voltage Vout, the power supply apparatus comprising:
- a transformer;
- an NPN transistor connected to a primary-side auxiliary winding of the transformer;
- a second resistance R2 connected between a base and a collector of the NPN transistor;
- a first zener diode whose anode is connected to a ground;
- a first resistance R1 connected between the base of the NPN transistor and a cathode of the first zener diode, the first resistance R1 being connected to the second resistance R2 in series;
- and
- a controller configured to operate based on power supplied to a Vcc terminal connected to the primary-side auxiliary winding of the transformer via the NPN transistor,
- wherein the NPN transistor is connected to the ground via the first zener diode and first resistance R1,
- the controller determines a voltage value of the Vcc terminal and controls to stop an output from the power supply apparatus in a case where the voltage value of the Vcc terminal is higher than a predetermined voltage value Vovp, and
- in a case where a rectified voltage obtained by rectifying an output from the primary-side auxiliary winding is denoted by Vaux, the rectified voltage Vaux at a time the output voltage Vout reaches a voltage at which the output from the power supply apparatus is stopped is denoted by Vauxer, a voltage in the first zener diode is denoted by VZ1, and a voltage between the base and an emitter of the NPN transistor is denoted by Veb, the values have a relationship expressed by the following formula:
- Vovp<(Vauxer−VZ1)*{R1/(R1+R2)}+VZ1−Veb (1).
A power supply apparatus capable of switching an output voltage Vout, the power supply apparatus comprising:
- a transformer;
- an NPN transistor connected to a primary-side auxiliary winding of the transformer;
- a second resistance R2 connected between a base and a collector of the NPN transistor;
- a first zener diode whose anode is connected to a ground;
- a first resistance R1 connected between the base of the NPN transistor and a cathode of the first zener diode, the first resistance R1 being connected to the second resistance R2 in series;
- and
- a controller configured to operate based on power supplied to a Vcc terminal connected to the primary-side auxiliary winding of the transformer via the NPN transistor,
- wherein the NPN transistor is connected to the ground via the first zener diode and first resistance R1, and
- the controller determines a voltage value of the Vcc terminal and controls to stop an output from the power supply apparatus in a case where the voltage value of the Vcc terminal is higher than a predetermined voltage Vovp.
A printing apparatus comprising:
- a power supply apparatus capable of switching an output voltage Vout;
- and
- a printing unit configured to perform printing for a print medium,
- wherein the power supply apparatus comprises:
- a transformer;
- an NPN transistor connected to a primary-side auxiliary winding of the transformer;
- a second resistance R2 connected between a base and a collector of the NPN transistor;
- a first zener diode whose anode is connected to a ground;
- a first resistance R1 connected between the base of the NPN transistor and a cathode of the first zener diode, the first resistance R1 being connected to the second resistance R2 in series;
- and
- a controller configured to operate based on power supplied to a Vcc terminal connected to the primary-side auxiliary winding of the transformer via the NPN transistor,
- wherein the NPN transistor is connected to the ground via the first zener diode and first resistance R1,
- the controller determines a voltage value of the Vcc terminal and controls to stop an output from the power supply apparatus in a case where the voltage value of the Vcc terminal is higher than a predetermined voltage value Vovp, and
- in a case where a rectified voltage obtained by rectifying an output from the primary-side auxiliary winding is denoted by Vaux, the rectified voltage Vaux at a time the output voltage Vout reaches a voltage at which the output from the power supply apparatus is stopped is denoted by Vauxer, a voltage in the first zener diode is denoted by VZ1, and a voltage between the base and an emitter of the NPN transistor is denoted by Veb, the values have a relationship expressed by the following formula:
- Vovp<(Vauxer−VZ1)*{R1/(R1+R2)}+VZ1−Veb (1).
Dependencies are inferred from the claim text.