Heater Wave-Number Control for High-Power Flicker Suppression
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Solution Overview
Problem
In high-speed image forming apparatuses, reducing the resistance value of heaters to increase suppliable power leads to worsened flicker in wave number control, necessitating an improvement in power supply methods.
Innovation Solution
A heating device with a control mechanism that performs wave number control by switching a switching element between conductive and non-conductive states based on detected temperature, adjusting power duty to maintain positive/negative symmetry and using specific power control patterns to optimize power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the resistance value of the heater is reduced to increase suppliable power, then the power supply capacity is improved, but the flicker performance deteriorates
Solution Approach 1:
The patent applies periodic action by using wave number control that operates over multiple AC voltage cycles (control periods spanning multiple half-waves). The control means periodically switches the triac on and off at zero-cross points over extended periods (e.g., 100ms, 200ms, or longer), transforming the continuous power supply into a controlled periodic pattern that reduces flicker while maintaining high power delivery capability to low-resistance heaters.
Solution Approach 2:
The patent changes the control parameters by adjusting the control period duration (number of AC cycles) and the duty ratio (ratio of on-time to total control period). By varying these parameters dynamically based on heater resistance and power requirements, the system optimizes both power delivery and flicker performance for different operating conditions.
2Device complexity
If wave number control is used to reduce noise and simplify filters, then the device complexity is reduced, but the flicker worsens when heater resistance is lowered
Solution Approach 1:
The patent maintains the simplicity of wave number control with zero-cross switching but extends the control period to multiple AC cycles. This periodic extension smooths out power delivery variations that cause flicker, allowing the system to maintain low device complexity without filters while improving flicker performance for high-power, low-resistance heater applications.
3Object-affected harmful factors
If the control period is extended to improve flicker performance, then the flicker is reduced, but the temperature control responsiveness decreases
Solution Approach 1:
The patent applies dynamics by making the control period duration variable rather than fixed. The control means dynamically adjusts the control period length and duty ratio based on real-time temperature feedback from the detection means. When rapid temperature changes are needed, shorter control periods are used for faster response; when steady-state operation is achieved, longer control periods are used to minimize flicker.
Solution Approach 2:
The patent implements feedback control where the detection means continuously monitors heater temperature and feeds this information back to the control means. The control means uses this feedback to dynamically adjust both the control period duration and duty ratio, optimizing the balance between flicker reduction and temperature control responsiveness based on current operating conditions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach improves flicker performance while increasing suppliable power to heaters, ensuring efficient and stable operation even with reduced resistance values.
Implementation Method 1
a heat generating member (111) connected to an AC power source (50)
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 3
AI summary
A heating device includes a heater, a switching element connected between the heater and an AC power, and a controller performing a wave number control. A power control pattern includes a first pattern of which a control period is a first number, equal to or more than 2, of half waves and which satisfies a positive/negative symmetry, and a second pattern of which the control period is a second number, equal to or more than 2 and divisible by 4, of half waves and which satisfies the positive/negative symmetry. The controller sets the second pattern in a case where a supplying power duty is a first duty and sets the first pattern in a case where the supplying power duty is a second duty which is the supplying power duty larger or smaller by one step than the first duty, and performs wave number control.