Power supply apparatus and heating apparatus and image forming apparatus
First Claim
1. A power supply apparatus comprising:
- a voltage detecting section for outputting a first pulse signal which is at a first voltage level when the AC power supply voltage is below a specified threshold value, and at a second voltage level when the AC power supply voltage exceeds the specified threshold value; and
a power control section for controlling supplied power in response to the first pulse signal fed from said voltage detecting section, wherein said power control section successively measures a period of an edge in one direction of the first pulse signal fed from said voltage detecting section, sets a set time period at a time period equal to half the period of the edge in one direction, and controls a switching device for switching between turning-on and turning-off of said AC power supply in accordance with timing of the edge in one deirection and timing when the set time period has elapsed after the edge in one direction.
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Accused Products
Abstract
A period of a first edge, a voltage change in a first direction of a first pulse signal fed from a zero-crossing detecting circuit, is detected. A second edge, a voltage change in a second direction opposite to the first direction, is generated when a time period equal to half the period of the first edge has elapsed from the next first edge. In response to a second pulse signal generated from the first and second edges, phase control of power to be supplied to heating elements is performed by using triacs. In this manner, during power control using a signal from the zero-crossing detecting circuit as a trigger signal, is achieved stable power control which enables tracking even though the power supply frequency fluctuates, and which is impervious to the effect of the positive or negative polarity of an input power supply.
18 Citations
11 Claims
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1. A power supply apparatus comprising:
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a voltage detecting section for outputting a first pulse signal which is at a first voltage level when the AC power supply voltage is below a specified threshold value, and at a second voltage level when the AC power supply voltage exceeds the specified threshold value; and
a power control section for controlling supplied power in response to the first pulse signal fed from said voltage detecting section, wherein said power control section successively measures a period of an edge in one direction of the first pulse signal fed from said voltage detecting section, sets a set time period at a time period equal to half the period of the edge in one direction, and controls a switching device for switching between turning-on and turning-off of said AC power supply in accordance with timing of the edge in one deirection and timing when the set time period has elapsed after the edge in one direction. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An image forming apparatus including an image forming section for forming a toner image on a recording medium, and a fuser for fusing the toner image on the recording medium by heating the toner image, wherein
said fuser comprises: -
heating means including a heating element;
temperature detecting section for detecting temperature of said heating means; and
the power supply apparatus which supplies power to the heating element of said heating means for heating, and wherein said power supply apparatus comprises;
a voltage detecting section for outputting a first pulse signal which is at a first voltage level when the AC power supply voltage is below a specified threshold value, and at a second voltage level when the AC power supply voltage exceeds the specified threshold value; and
a power control section for controlling supplied power in response to the first pulse signal fed from said voltage detecting section, wherein said power control section successively measures a period of an edge in one direction of the first pulse signal fed from said voltage detecting section, sets a set time period at a time period equal to half the period of the edge in one direction, and controls a switching device for switching between turning-on and turning-off of said AC power supply in accordance with timing of the edge in one deirection and timing when the set time period has elapsed after the edge in one direction.
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Specification