Image forming apparatus
AssigneeBrother Kogyo Kabushiki Kaisha
InventorHuimin HE
Life of this patent
Estimating the term…
Abstract
A heating system includes a heater, a switching circuit providing alternating current to the heater, and a current sensor. The heating system also includes a controller that controls operation of the switching circuit. At a predetermined time during a half cycle, the controller outputs an activation signal to the switching circuit. Based on an elapsed time from outputting the activation signal that a current signal is at least at a predetermined level, the controller calculates a second time from which a current level does not exceed a threshold level during the half cycle, and outputs an activation signal to the switching circuit at the second time. The heating system is useable within an image forming apparatus.
Claims21
A heating system comprising:
- a heater;
- a switching circuit connected to the heater and configured to be turned on by a turn-on signal, the switching circuit (50) being turned on when alternating current is supplied to the heater;
- a current sensor connected between the heater and the switching circuit, the current sensor being configured to output a signal corresponding to a value of current flowing in the current sensor;
- and
- a controller configured to:
- output to the switching circuit, the turn-on signal at a time corresponding to a first phase angle (xn) in a particular half cycle (Hn) of the alternating current;
- determine a period of time (tn) from the time of the turn-on signal in which a value of current represented by a signal output by the current sensor continues to be greater than or equal to a first threshold (y0) during the particular half cycle;
- calculate a second phase angle (x(n+1)) based on the determined period of time (tn);
- and
- output to the switching circuit, the turn-on signal at a time corresponding to the calculated second phase angle (x(n+1)) in a half cycle (H(n+1)) following the particular half cycle (Hn).
An image forming apparatus comprising:
- a heater;
- a switching circuit electrically connected between an alternating current power supply and the heater;
- a current sensor electrically connected between the switching circuit and the heater, the current sensor configured to output a current signal representing a sensed current;
- and
- a controller communicatively connected to the switching circuit and the current sensor, the controller being configured to:
- at a predetermined time during a half cycle of an alternating current signal provided by the alternating current power supply, output an activation signal to the switching circuit to provide alternating current to the heater;
- receive the current signal from the current sensor indicative of the alternating current supplied to the heater;
- based on an elapsed time from the outputting of the activation signal that the current signal is at least at a predetermined signal level during the half cycle, calculate a second time from which the alternating current signal does not exceed a current threshold for a remainder of the half cycle;
- and
- during a second half cycle of the alternating current signal following the half cycle, output a second activation signal to the switching circuit at the calculated second time.
An image forming apparatus comprising:
- a heater;
- a switching circuit electrically connected between an alternating current power supply and the heater;
- a current sensor electrically connected between the switching circuit and the heater, the current sensor configured to output a current signal corresponding to a sensed current and having a maximum current value output when the sensed current is greater than or equal to a first current value;
- and
- a controller communicatively connected to the switching circuit and the current sensor, the controller being configured to:
- at a predetermined time during a half cycle of an alternating current signal provided by the alternating current power supply, output an activation signal to the switching circuit to provide alternating current to the heater;
- receive the current signal from the current sensor indicative of the alternating current supplied to the heater;
- and
- based on a determination that the current signal is at the maximum current value during the half cycle for at least some time period, in a second half of a subsequent half cycle, output a second activation signal to the switching circuit at a second time offset from completion of the subsequent half cycle a greater amount than the predetermined time is offset from completion of the half cycle.
Dependencies are inferred from the claim text.