US-12625445-B2 - Power control device, fixing device, and image forming apparatus

US12625445B2US 12625445 B2US12625445 B2US 12625445B2US-12625445-B2

Abstract

A power control device includes a heater, a zero-cross detecting unit, a triac, a supplying unit, and a controlling unit. The supplying unit discharges an electric charge when a control signal is outputted in a half-wave of each of a first polarity and a second polarity and charges the electric charge when the control signal is not outputted in the half-wave of the first polarity. The controlling unit outputs: in a first half-wave, a first control signal on the basis of the zero-cross point and a second control signal in a first phase different in timing from the first control signal, and in a second half-wave, a third control signal on the basis of the zero-cross point and a fourth control signal in a second phase different in timing from the second control signal. The first phase and the second phase are different from each other.

Inventors

Satoru Nagashima
Kouji Yasukawa
Yusuke Nakashima

Assignees

CANON KABUSHIKI KAISHA

Dates

Publication Date: 20260512
Application Date: 20241031
Priority Date: 20220228

Claims (11)

1 . A power control device comprising: a heater configured to generate heat by being supplied with an AC voltage; a zero-cross detecting unit configured to detect a zero-cross point of the AC voltage; a triac configured to switch a conduction state in which the AC voltage is supplied to the heater and a non-conduction in which supply of the AC voltage to the heater is cut off; a supplying unit configured to supply a current to the triac; and a controlling unit configured to control a state of the triac by outputting a control signal, wherein the controlling unit controls the state of the triac by outputting the control signal in a control period in which a plurality of half waves of the AC voltage with a first polarity and a plurality of half waves of the AC voltage with a second polarity different from the first polarity constitute one period of control, wherein the supplying unit discharges an electric charge when the control signal is outputted in the half wave of each of the first polarity and the second polarity and charges the electric charge when the control signal is not outputted in the half wave of the first polarity, wherein the controlling unit outputs: in a first half wave, a first control signal on the basis of the zero-cross point as a reference and a second control signal after a delay time Δt 1 , and in a second half wave, a third control signal on the basis of the zero-cross point as a reference and a fourth control signal after a delay time Δt 2 , where Δt 1 ≠Δt 2 .
2 . A power control device according to claim 1 , wherein the controlling unit outputs the second control signal in the half wave of the second polarity in the control period and outputs the fourth control signal in the half wave of the first polarity in the control period.
3 . A power control device according to claim 1 , wherein the controlling unit outputs the second control signal or the fourth control signal at a random timing on the basis of the zero-cross point as a reference for each of the half waves in the control period.
4 . A power control device comprising: a heater configured to generate heat by being supplied with an AC voltage; a zero-cross detecting unit configured to detect a zero-cross point of the AC voltage; a triac configured to switch a conduction state in which the AC voltage is supplied to the heater and a non-conduction in which supply of the AC voltage to the heater is cut off; a supplying unit configured to supply a current to the triac; and a controlling unit configured to control a state of the triac by outputting a control signal, wherein the controlling unit controls the state of the triac by outputting the control signal in a control period in which a plurality of half waves of the AC voltage with a first polarity and a plurality of half waves of the AC voltage with a second polarity different from the first polarity constitute one period of control, wherein the supplying unit discharges an electric charge when the control signal is outputted in the half wave of each of the first polarity and the second polarity and charges the electric charge when the control signal is not outputted in the half wave of the first polarity, wherein the controlling unit changes a number of outputs of the control signal outputted in the plurality of the half waves by every control period, and wherein the controlling unit outputs: in a first half wave, a first control signal on the basis of the zero-cross point as a reference and a second control signal after a delay time At 1 , and in a second half wave, a third control signal on the basis of the zero-cross point as a reference and a fourth control signal after a delay time Δt 2 , where Δt 1 ≈Δt 2 .
5 . A power control device according to claim 4 , wherein the controlling unit outputs the control signal a first number of times in a first half wave and outputs the control signal a second number of times in a second half wave, and wherein the first number of times and the second number of times are different from each other.
6 . A power control device comprising: a heater configured to generate heat by being supplied with an AC voltage; a zero-cross detecting unit configured to detect a zero-cross point of the AC voltage; a triac configured to switch a conduction state in which the AC voltage is supplied to the heater and a non-conduction in which supply of the AC voltage to the heater is cut off; a supplying unit configured to supply a current to the triac; and a controlling unit configured to control a state of the triac by outputting a control signal, wherein the controlling unit controls the state of the triac by outputting the control signal in a control period in which a plurality of half waves of the AC voltage with a first polarity and a plurality of half waves of the AC voltage with a second polarity different from the first polarity constitute one period of control, wherein the supplying unit discharges an electric charge when the control signal is outputted in the half wave of each of the first polarity and the second polarity and charges the electric charge when the control signal is not outputted in the half wave of the first polarity, wherein the controlling unit outputs the control signal a first number of times in a first half wave and outputs the control signal a second number of times in a second half wave, wherein the half wave, in which the controlling unit outputs the control signal a plurality of times includes the half wave in which the controlling unit outputs a first control signal on the basis of the zero-cross point as a reference and a second control signal after a delay time Δt 1 , and includes the half wave in which the controlling unit outputs a third control signal on the basis of the zero-cross point as a reference and a fourth control signal after a delay time Δt 2 , where Δt 1 /Δt 2 , and wherein the first number of times and the second number of times are different from each other, and the first phase and the second phase are different from each other.
7 . A power control device according to claim 6 , wherein the controlling unit outputs the control signal the first number of times in the half wave of the second polarity in the control period and outputs the control signal the second number of times in the half wave of the first polarity in the control period, and wherein the controlling unit carries out control so that in the half waves of the first polarity, the half wave in which the controlling unit outputs the second control signal and the half wave in which the controlling unit outputs the fourth control signal are alternately generated.
8 . A power control device according to claim 1 , wherein the zero-cross detecting unit detects the half wave of the AC voltage with one of the first and second polarities.
9 . A power control device according to claim 1 , wherein the controlling unit updates an output method of the control signal in a predetermined half wave by every control period.
10 . A fixing device for fixing an unfixed toner image on a recording material, comprising: control device according to claim 1 ; a film heated by the heater; and a pressing roller forming a nip in cooperation with the film, wherein the heater is provided in an inside space of the film and nips the film by itself and the pressing roller, and wherein the toner image on the recording material is heated through the film.
11 . An image forming apparatus comprising: an image forming unit configured to form a toner image on a recording material; and device according to claim 10 .

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional of application Ser. No. 18/163,831 filed Feb. 2, 2023, currently pending; and claims priority under 35 U.S.C. § 119 to Japan Application JP2022-029268 filed in Japan on Feb. 28, 2022; and the contents of all of which are incorporated herein by reference as if set forth in full. FIELD OF THE INVENTION AND RELATED ART The present invention relates to a power control device, a fixing device and an image forming apparatus and, for example, relates to a control method of a circuit for controlling electric power supplied to an image heat fixing device mounted in the image forming apparatus such as a copying machine or a laser beam printer. There is a circuit in which electric power is supplied from an AC power source to a load by controlling electric power supply to a bidirectional thyristor (hereinafter, referred to as a triac) (hereinafter, such control is referred to as electric power control). In such a circuit, as a technique in which a power source different from the AC power source is provided and the electric power control is carried out by passing a gate current from the different power source to the triac, for example, a proposal such as Japanese Laid-Open Patent Application (JP-A) 2002-247758 has been made. On the other hand, it has been known in general that due to distortion of an AC voltage of the AC power source and superposed noise, the triac turns off. As a method in which the triac is prevented from turning off due to the noise and the electric power control is carried out, for example, a proposal such as JP-A 2001-326087 has been made. In JP-A 2001-326087, a proposal has been made as to a technique such that electric charges are continuously supplied to a power source for supplying the gate current to the triac in order to substantially continuously turn on the triac. However, in the circuit in which the triac is subjected to the electric power control by passing the gate current from the power source disposed separately from the conventional power source, the following problem arises. In order to substantially continuously turn on the triac, there is a need to continuously supply the gate current to the triac. There is a constraint on capacity of the power source provided separately from the AC power source, so that there is limitation on a time in which the gate current is capable of being supplied to the triac. Or, in order to continuously supply the gate current to the triac, there is a need to provide a power source having a large electric charge capacity. Therefore, in order to continuously supply the gate current to the triac, there is a need to continuously charging the electric charges to the power source provided separately from the AC power source by using a circuit element such as a transformer or a bridge diode. For this reason, in the circuit in which the gate current is supplied to the triac from the power source provided separately from the AC power source, it has been required that the triac is continuously controlled while avoiding the influence by the distortion of the AC power source and the noise as can as possible by a simple means while suppressing an increase in cost. SUMMARY OF THE INVENTION According to an aspect of the present invention, there is provided a power control device comprising: a heater configured to generate heat by being supplied with an AC voltage; a zero-cross detecting unit configured to detect a zero-cross point of the AC voltage; a triac configured to switch a conduction state in which the AC voltage is supplied to the heater and a non-conduction in which supply of the AC voltage to the heater is cut off; a supplying unit configured to supply a current to the triac; and a controlling unit configured to control a state of the triac by outputting a control signal, wherein the controlling unit controls the state of the triac by outputting the control signal in a control period in which a plurality of half-waves of the AC voltage with a first polarity and a plurality of half-waves of the AC voltage with a second polarity different from the first polarity constitute one period of control, wherein the supplying unit discharges an electric charge when the control signal is outputted in the half-wave of each of the first polarity and the second polarity and charges the electric charge when the control signal is not outputted in the half-wave of the first polarity, wherein the controlling unit outputs: in a first half-wave, a first control signal on the basis of the zero-cross point as a reference and a second control signal in a first phase different in timing from the first control signal, and in a second half-wave, a third control signal on the basis of the zero-cross point as a reference and a fourth control signal in a second phase different in timing from the second control signal, and wherein the first phase and the second phase are different from each other. Further features of