Thermostat Backlight Control for Accurate Temperature Sensing
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Solution Overview
Problem
Temperature control devices, such as thermostats, face inaccuracies in temperature measurement due to heat generated by internal components like display screens and button backlights, which can deviate from actual space temperatures, affecting HVAC system performance.
Innovation Solution
A temperature control device with a control circuit that adjusts its power consumption and sampling frequency to minimize heat generation, using ambient light detection to optimize backlight intensity and reduce heat impact on temperature readings, allowing for accurate temperature measurement and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the display screen and button backlight operate at high intensity to improve visibility and user interaction, then illumination intensity is improved, but heat generation increases causing temperature measurement inaccuracies
Solution Approach 1:
The button backlight operates in periodic cycles of high intensity (during user interaction) and low or zero intensity (during idle periods). The control circuit switches the backlight between these states based on detected user activity, allowing accurate temperature measurements during idle low-heat periods while maintaining visibility during active periods.
Solution Approach 2:
The button backlight intensity is dynamically adjusted based on operational state. The system transitions between static high-intensity operation and dynamic periodic operation, adapting the backlight intensity to current needs. This dynamic adjustment allows the system to optimize between visibility requirements and measurement accuracy requirements.
2Ease of operation
If the electrical load operates continuously in awake state to maintain responsiveness, then ease of operation is improved, but heat generation and energy consumption increase
Solution Approach 1:
The control circuit alternates between awake state (high responsiveness, high power consumption) and idle state (reduced responsiveness, low power consumption). During idle periods, the system enters a low-power state with periodic sampling, then transitions back to full awake state when user interaction is detected, balancing responsiveness needs with energy conservation.
Solution Approach 2:
The system automatically transitions between operational states based on detected user activity without requiring manual intervention. The control circuit monitors for button presses or other user inputs and autonomously adjusts the operational state, power consumption level, and sampling frequency accordingly.
3Measurement precision
If temperature sampling frequency is increased to improve measurement accuracy, then measurement precision is improved, but heat generation and energy consumption increase
Solution Approach 1:
The temperature sampling operates periodically rather than continuously. During idle periods, sampling occurs at reduced frequency or is suspended entirely. When user interaction is detected and the system transitions to awake state, sampling frequency increases to provide more frequent measurements, optimizing the balance between measurement accuracy and energy consumption.
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
The solution enables precise temperature control and measurement by reducing the heat impact from internal components, improving the accuracy of temperature readings and energy efficiency.
Implementation Method 1
a light detector circuit configured to measure an ambient light level around the control device
Implementation Method 2
the display screen may give off heat when it is operating... the heat given off by the display screen may throw off the measurements provided by the thermostat
Data Source
AI summary
A temperature control device (e.g., a thermostat) may be configured to control an internal heat-generating electrical load so as to accurately measure a present temperature in a space around the temperature control device. The temperature control device may comprise a temperature sensing circuit configured to generate a temperature control signal indicating the present temperature in the space, and a control circuit configured to receive the temperature control signal and to control the internal electrical load. The control circuit may be configured to energize the internal electrical load in an awake state and to cause the internal electrical load to consume less power in an idle state. The control circuit may be configured to control the internal electrical load to a first energy level (e.g., a first intensity) during the awake state and to a second energy level (e.g., second intensity) that is less than the first during the idle state.