Optical Motion Sensor Dynamic Hysteresis Threshold
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Solution Overview
Problem
Optical pointing devices face challenges in preventing false motion detection and excessive power consumption when at rest, particularly on low contrast surfaces, due to the fixed hysteresis threshold settings which require a trade-off between motion detection sensitivity and power efficiency.
Innovation Solution
The method involves dynamically adjusting the hysteresis value of comparators based on the device's state, setting a low hysteresis value when moving and a high value when at rest, allowing for reliable motion tracking on low contrast surfaces while reducing false motion detection and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed hysteresis threshold is used for motion detection, then the device can maintain stable operation, but it causes false motion detection on low contrast surfaces and excessive power consumption when at rest
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed hysteresis threshold to a dynamically adjustable threshold that adapts based on device state (motion vs. rest). The system automatically increases the threshold when motion is detected and decreases it when the device is at rest, resolving the contradiction between reliable motion detection and power consumption efficiency
Solution Approach 2:
The patent implements parameter changes by modifying the hysteresis threshold value based on operational conditions. The threshold parameter is changed from a static fixed value to a dynamic value that increases during motion detection to improve reliability and decreases during rest periods to reduce power consumption, directly addressing the technical contradiction
2Use of energy by moving object
If a high hysteresis threshold is set to prevent false motion detection at rest, then power consumption is reduced, but motion detection sensitivity decreases on low contrast surfaces
Solution Approach 1:
The system uses dynamics to adjust the hysteresis threshold based on device state. When motion is detected, the threshold is lowered to maintain high sensitivity for detecting motion on low contrast surfaces. When the device is at rest, the threshold is raised to prevent false detection and reduce power consumption, thus resolving the contradiction between power efficiency and detection sensitivity
3Measurement precision
If a low hysteresis threshold is set to improve motion detection sensitivity on low contrast surfaces, then false motion detection increases when at rest, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the hysteresis threshold adjustable based on device state. The system maintains low threshold values during motion to ensure high sensitivity for detecting subtle movements on low contrast surfaces, while automatically increasing the threshold during rest periods to eliminate false detections and reduce power consumption, resolving the reliability-sensitivity contradiction
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 prevents false motion detection when the device is at rest and ensures accurate motion tracking on low contrast surfaces, thereby optimizing power usage and detection performance.
Implementation Method 1
a photodetector device (320) which is a photodetector array including a plurality of pixels, responsive to radiation reflected from the illuminated surface portion S
Implementation Method 2
each for comparing the light intensity of a first pixel of array 320 with the light intensity of a second pixel of array 320 and for outputting a resulting edge direction condition
Data Source
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AI summary
A method for operating an optical motion sensing device comprising a light source and a photodetector device, said method comprises the steps of: a) illuminating a surface portion with radiation by means of the light source; b) detecting radiation patterns reflected from the illuminated surface portion by means of the photodetector device; c) extracting motion features from the detected radiation patterns by comparing light intensity between neighbouring pixels of said photodetector device by means of comparators with a determined hysteresis threshold; d) detecting and measuring displacement with respect to the illuminated surface portion based on said extracted motion features; e) determining whether the optical motion sensing device is moving or at rest; f) adjusting said determined hysteresis threshold of the comparators between at least a low and a high hysteresis values, consisting in selecting said low hysteresis value when the optical motion sensing device is moving and selecting said high hysteresis value when the optical motion sensing device is at rest.