Trend-Based Temperature Compensation for Camera Focus Stability
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Solution Overview
Problem
Monitoring devices, such as cameras, face challenges in maintaining stable focus due to environmental changes like temperature fluctuations, which affect the optics chain and sensor elements, leading to changes in the back focus that need to be compensated for.
Innovation Solution
The monitoring device detects temperature changes above a threshold, retrieves trend-based motor position settings from a memory, performs a just noticeable difference (JND) modification on the focus motor to adjust the focus, and selects a temperature-adjusted motor position setting to maintain stable focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If temperature compensation is performed using traditional methods, then focus stability may be improved, but the complexity of the compensation algorithm and processing time increase
Solution Approach 1:
The system performs preliminary actions by storing motor position settings from previous temperature conditions in a lookup table during normal operation. When temperature changes exceed a threshold, the system retrieves pre-stored trend-based settings rather than performing complex real-time calculations, thus maintaining focus stability while reducing processing complexity and time.
Solution Approach 2:
The patent replaces complex mechanical/optical measurement and adjustment systems with an electronic lookup table system. Instead of using sophisticated algorithms to calculate focus adjustments in real-time, the system substitutes a simple retrieval operation from pre-stored data, significantly reducing computational complexity while maintaining compensation effectiveness.
2Stability of the object's composition
If the focus motor is adjusted continuously to compensate for temperature changes, then focus stability improves, but the risk of over-adjustment and focus oscillation increases
Solution Approach 1:
The system applies partial action by using just noticeable difference (JND) modifications on the retrieved motor position settings. Rather than applying full compensation based on historical data, the system makes subtle adjustments that are just sufficient to maintain focus stability, avoiding over-adjustment while still effectively compensating for temperature-induced focus drift.
Solution Approach 2:
The system incorporates feedback mechanisms by continuously monitoring temperature changes and only triggering compensation when temperature changes exceed a predefined threshold. This feedback approach prevents unnecessary adjustments during stable temperature conditions, reducing the risk of focus oscillation while maintaining stability when needed.
3Speed
If a simple lookup table approach is used for temperature compensation, then processing speed improves, but the precision of focus adjustment may deteriorate
Solution Approach 1:
The system performs preliminary action by pre-calculating and storing motor position settings for various temperature conditions in a lookup table. This allows the system to retrieve pre-computed values quickly without performing complex real-time calculations, thereby maintaining high processing speed while ensuring precision through pre-optimized adjustment values.
Solution Approach 2:
The system applies dynamics by using trend-based settings that capture the dynamic relationship between temperature changes and focus adjustments. The lookup table stores not just static values but trend information that adapts to changing environmental conditions, allowing the system to maintain precision across varying operating conditions while benefiting from fast lookup operations.
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 effectively compensates for temperature-induced changes in the focal plane, ensuring a stable focus level by using trend-based settings and JND modifications, thereby maintaining image quality despite environmental temperature variations.
Implementation Method 1
Changes in the environment may affect the back focus, by, for example, moving optical elements and/or sensor elements of the monitoring device
Data Source
AI summary
A method, performed by a monitoring device, may include detecting a temperature change, greater than a temperature change threshold, from a previous temperature to a current temperature; retrieving a trend-based motor position setting for a focus motor from a trend statistics memory based on the current temperature; and selecting a starting motor position setting for the focus motor based on the retrieved trend-based motor position setting or a current motor position setting. The method may further include performing a just noticeable difference modification on the focus motor using the selected starting motor position setting, wherein the just noticeable difference corresponds to a change in a motor position setting that results in a perceivable change in a focus level of the monitoring device, and selecting a temperature adjusted motor position setting for the focus motor based on a result of the just noticeable difference modification.