Optical Motion Sensor Shutter Control for Low-Noise Detection
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Solution Overview
Problem
Conventional optical sensor devices suffer from degraded performance due to varying shot noise levels under different light conditions, leading to false motion detection and high power consumption.
Innovation Solution
An optical sensor device with a pixel array and control circuit that uses BJT sensing pixels, employing two integration capacitors and varying shutter exposure times to capture and compare image signals, thereby enhancing motion detection sensitivity and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical sensor devices use fixed shutter exposure time, then the device structure is simple, but the motion detection accuracy degrades due to varying shot noise levels under different light conditions
Solution Approach 1:
The patent applies dynamics by making the shutter exposure time adjustable rather than fixed. The control circuit dynamically changes the shutter exposure time based on detected light conditions to optimize motion detection accuracy. This resolves the contradiction by allowing the system to adapt to varying shot noise levels while maintaining relatively simple hardware structure through software/control-based adjustment.
Solution Approach 2:
The patent changes the parameter of shutter exposure time according to light conditions. By varying this parameter dynamically, the system maintains optimal motion detection performance across different lighting scenarios. This parameter adjustment approach improves measurement precision without requiring complex hardware modifications.
2Measurement precision
If conventional optical sensor devices increase shutter exposure time to improve signal strength, then motion detection sensitivity improves, but power consumption increases
Solution Approach 1:
The system dynamically adjusts shutter exposure time based on real-time light condition detection. When light conditions are good, it uses shorter exposure times to reduce power consumption. When light conditions are poor, it extends exposure time to maintain sensitivity. This dynamic adjustment resolves the contradiction between sensitivity and power consumption.
Solution Approach 2:
The patent changes the shutter exposure time parameter adaptively. By optimizing this parameter based on environmental light conditions, the system achieves high motion detection sensitivity when needed while minimizing power consumption during normal operating conditions, thus resolving the trade-off between these two parameters.
3Stability of the object's composition
If conventional optical sensor devices use high integration capacitor capacity to reduce noise, then signal stability improves, but the device size and complexity increase
Solution Approach 1:
Instead of using larger capacitors to stabilize signals, the patent dynamically adjusts shutter exposure time to optimize signal quality. This control-based approach achieves signal stability without requiring increased capacitor capacity, thereby avoiding the associated complexity and size increase.
Solution Approach 2:
The patent replaces the mechanical approach of using larger capacitors with a control-based solution. By using software/control circuitry to adjust exposure time, it achieves the same signal stabilization effect without the hardware complexity and size penalty of larger capacitor components.
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 accurately determines motion in images while consuming lower power by dynamically adjusting shutter exposure times and threshold voltages, improving sensitivity and reducing false motion detection.
Implementation Method 1
a photo transistor, a first integration capacitor, and a second integration capacitor. The photo transistor is configured to capture and generate a first image signal during a first shutter exposure time interval
Data Source
AI summary
An optical sensor device includes a pixel array and a control circuit. The pixel array has pixel units arranged in N rows and M columns, and a pixel unit comprises: a photo transistor, configured to capture and generate a first image signal during a first shutter exposure time interval of a first time and to capture and generate a second image signal during a second shutter exposure time interval of a second time, the first time and the second time being consecutive; a first integration capacitor, coupled to the photo transistor, for storing the first image signal; and a second integration capacitor, coupled to the photo transistor, for storing the second image signal. The control circuit performs a motion detection to determine whether a motion occurs according to a difference between the two image signals.