Camera Motion Sensor Cool-Off Control by Event Length
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Solution Overview
Problem
PIR sensors in camera devices are sensitive to heat generated by other components, leading to inaccurate motion detection (false positives) or missed detections (false negatives) due to heat-induced sensitivity fluctuations.
Innovation Solution
Implementing adaptive cool-off periods for motion sensors based on the duration of high-power component usage, where the length of the cool-off period is determined by the heat generation and sensitivity of the motion sensor, ensuring accurate motion detection while conserving power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the motion sensor is continuously used for motion detection, then motion detection coverage is improved, but detection accuracy deteriorates due to heat-induced sensitivity fluctuations
Solution Approach 1:
The system performs preliminary cooling action by disabling the motion sensor after a high-power event before motion detection is needed again. This preliminary cooling prevents the sensor from being too hot for accurate detection, thereby resolving the contradiction between continuous detection coverage and detection accuracy.
Solution Approach 2:
The system implements periodic motion detection by alternating between active detection periods and cool-off periods. During high-power events, the motion sensor is disabled; during normal periods, it is active. This periodic operation maintains detection accuracy while preserving overall detection coverage.
2Measurement precision
If the cool-off period is extended to ensure sensor cooling, then detection accuracy is improved, but power efficiency deteriorates due to unnecessary downtime
Solution Approach 1:
The system dynamically adjusts the cool-off period duration based on the actual high-power event duration and sensor cooling rate. Rather than using a fixed extended cool-off period, the system calculates the minimum necessary cooling time, thereby maintaining detection accuracy while maximizing power efficiency by minimizing unnecessary downtime.
3Measurement precision
If the motion sensor is disabled during cool-off period, then false positives are reduced, but false negatives increase due to missed detections
Solution Approach 1:
The system uses feedback from high-power event detection to control the motion sensor state. When a high-power event is detected, the system feeds back to disable the motion sensor, preventing false positives. The cool-off period duration is determined by the event duration, providing adaptive feedback control that balances false positive reduction with false negative minimization.
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
Balances false positives and false negatives by dynamically adjusting the cool-off period, allowing the motion sensor to regain accuracy without unnecessary downtime, thus enhancing detection reliability and power efficiency.
Implementation Method 1
A passive infrared (PIR) sensor measures infrared light radiating from objects in its field of view. A PIR sensor can detect motion by detecting changes in the amount of infrared radiation impinging upon it.
Implementation Method 2
Some types of electronic components in camera devices generate heat when functioning. This heat may spread to the PIR sensor and increase its sensitivity
Data Source
Figure 1
Figure 2A~2B
Figure 2C
AI summary
A method including, at a camera, detecting motion in a field of view of the camera using a motion sensor, initiating processing of video data corresponding to the field of view in which the motion was detected, ceasing the processing after a first time duration, and determining a cool-off period for the motion sensor, the cool-off period having a second time duration based on the first time duration during which the camera does not detect motion using the motion sensor.