Appliance LED Brightness Control Under Chamber Heat
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Solution Overview
Problem
Conventional methods for controlling light intensity in appliances with light emitting devices, such as LEDs, either maintain low intensity to prevent damage at high temperatures or increase complexity and cost by using temperature-dependent variable current driving, failing to adapt effectively to varying operating conditions.
Innovation Solution
An appliance with a light emitting device and a controller that adjusts the light intensity based on temperature values within the chamber, using pulse width modulation or triac control to dynamically modify the driving signal, ensuring reliable operation and adaptability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light emitting device is driven at high current to increase light intensity, then the illumination level improves, but the device suffers premature damage due to high temperature
Solution Approach 1:
The patent applies dynamics by transitioning from static direct drive to dynamic pulse width modulation (PWM) control. The driving current is made variable through PWM signals that dynamically adjust the duty cycle based on temperature conditions, allowing the system to optimize between light intensity and device protection in real-time rather than being fixed at a conservative low intensity level
Solution Approach 2:
The patent changes the driving parameter from constant current to variable current controlled by PWM duty cycle. By modifying the duty cycle parameter in response to temperature changes, the system can deliver high current pulses when cool for maximum brightness while reducing average current when temperature rises, thus protecting the device while maintaining illumination capability
2Reliability
If the light intensity is maintained at low level to prevent damage, then the device reliability improves, but the user cannot read the display or see within the chamber effectively
Solution Approach 1:
The patent implements periodic action through PWM control, where the light emitting device is driven in periodic pulses rather than continuous DC. This allows the device to receive high current in brief pulses for maximum brightness when needed, while the average power remains controlled to prevent overheating, effectively decoupling peak intensity from thermal load
Solution Approach 2:
The system dynamically adjusts the PWM duty cycle based on real-time temperature feedback, allowing the light intensity to be high when the device is cool and automatically reducing intensity when temperature rises, thus maintaining both user visibility and device reliability under varying operating conditions
3Reliability
If temperature-dependent variable current driving is used to protect the LED, then the device reliability improves, but the complexity and cost of detection and driving circuits increases
Solution Approach 1:
The patent applies self-service by utilizing the existing temperature sensor and controller that are already part of the appliance's normal operation. Rather than adding dedicated LED protection circuitry, the system leverages the appliance's existing temperature monitoring capabilities to control the LED, making the protection mechanism self-integrated and avoiding additional complexity
Solution Approach 2:
The existing temperature sensor and controller serve multiple functions: they monitor chamber temperature for cooking operations and simultaneously control LED intensity for protection. This multi-functionality eliminates the need for separate dedicated temperature-dependent driving circuits, reducing overall system complexity while achieving reliable LED protection
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
Enables increased light intensity while protecting the light emitting device from premature damage, reducing complexity and cost by dynamically adjusting the light intensity in response to temperature changes, enhancing user experience and appliance reliability.
Implementation Method 1
The light emitting device can be a light emitting diode, a liquid crystal display, or other type of device that includes an element having a light intensity. When the light emitting device is a light emitting diode (LED), driving the LED at a high current in a high temperature environment causes premature damage to the light emitting device.
Implementation Method 2
A method of variably controlling a drive signal to a light emitting device of the appliance based on a temperature value indicative of a temperature within a chamber of the appliance... using pulse width modulation or triac control to dynamically modify the driving signal
Data Source
AI summary
An appliance and method for variably controlling a drive signal to a light emitting device of the appliance based on a temperature value indicative of a temperature within a chamber of the appliance is provided. The light emitting device can be included in a display or disposed within a chamber of the appliance to provide illumination. The light intensity level of the light emitting device can be controlled based on the temperature value indicative of a temperature within the chamber. The temperature value indicative of a temperature within the chamber can be a value detected within the chamber, a value detected on a surface of the chamber, or a value that anticipates the temperature within the chamber. The light intensity can be controlled with a driving signal to the light emitting device. For instance, the light intensity can be controlled using pulse width modulation of the driving signal.