Independent Temperature Control Circuit for Dual Heater Wires
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Solution Overview
Problem
Existing temperature control circuits for heating devices, such as hot packs, are inefficient in controlling two heater wires simultaneously, leading to increased manufacturing costs and limited flexibility in usage, as they require separate circuits and can only heat or stop both devices at the same time, disrupting the hot compress function.
Innovation Solution
A temperature control circuit using a bi-directional thyristor, diodes, and a controller that connects the heater and sensing wires in parallel, allowing for independent control of two heating devices by utilizing the positive and negative half-periods of alternating current, enabling separate or simultaneous operation of the devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If two separate temperature control circuits are used for two heater wires, then each heater wire can be controlled independently, but the manufacturing cost increases
Solution Approach 1:
The patent combines two separate temperature control circuits into a single integrated circuit that can control two heater wires independently. The controller receives temperature signals from both sensing wires and generates control signals for both heater wires through a unified control logic, thereby reducing component count and manufacturing cost while maintaining independent control capability
Solution Approach 2:
The single temperature control circuit is designed with multi-functionality to handle both heater wires. The controller can selectively activate heating for the first heater wire, second heater wire, both, or neither based on their respective temperature conditions, making the circuit universal for controlling multiple heating devices
2Device complexity
If one switch is used for controlling two heater wires, then the circuit complexity is reduced, but both heater wires can only be heated or stopped at the same time
Solution Approach 1:
The control system dynamically adjusts the heating state of each heater wire based on real-time temperature feedback. The controller can independently switch between different heating modes (first heater only, second heater only, both heaters, or neither) by processing temperature signals from both sensing wires and generating corresponding control signals, providing flexible and adaptive heating control
3Device complexity
If one switch controls two heater wires placed at different locations, then the circuit is simplified, but the controller uses the highest temperature for control, causing the heater that has reached preset temperature to continue heating when the other has not
Solution Approach 1:
The system implements independent feedback loops for each heater wire through separate sensing wires. Each sensing wire continuously monitors the temperature of its corresponding heater wire and sends signals to the controller. The controller processes both temperature signals independently and adjusts each heater wire's heating state based on its own temperature feedback, ensuring accurate temperature control for each heating device regardless of location
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 solution allows for flexible usage of two heating devices simultaneously or separately, while reducing manufacturing costs by simplifying the circuit elements and ensuring accurate temperature control of each device independently.
Implementation Method 1
U.S. Pat. No. 5,861,610 employs a positive temperature coefficient (PTC) element as the sensing wire to sense the changes in temperature
Implementation Method 2
U.S. Pat. No. 7,180,037 discloses an invention employing a positive temperature coefficient (PTC) element or a negative temperature coefficient (NTC) element
Implementation Method 3
The controller comprises a trigger circuit and the trigger circuit is connected with a gate of the bi-directional thyristor so that a controller switch can conduct the alternating current in two half-waves or one half-wave
Implementation Method 4
Two heater wires of the two heating devices can be heated up respectively by the positive half-period and negative half-period of alternating current
Data Source
AI summary
A temperature control circuit for two heating devices respectively provided with a heater and a sensing wire. The sensing wires' ends are respectively connected to a diode. The two diodes' polarity is opposite to that of the sensing wires' connecting ends. Another ends of the sensing wires are connected to a capacitor to form a resistor-capacitor circuit. The heater wires are connected to a diode respectively and then a bi-directional thyristor. The two diodes' polarity is opposite to that of the heater wires' connecting ends. Thereby, the heater wires can be heated up respectively by the positive and negative half-periods of alternating current. When phase shifts occur because of the heater wires' temperature change, the sensing wires can control the bi-directional thyristor via a controller so that the positive or negative half-period are not triggered. Therefore, the heater wires' heating temperatures can be controlled individually.