BJT Pixel Circuit for Motion Detection Without Image Storage
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Solution Overview
Problem
Conventional motion detection systems require significant memory and computational resources due to the need to store and compare entire images, leading to inefficiencies in memory usage and processing complexity.
Innovation Solution
An image sensor comprising a BJT pixel circuit, biasing circuit, and comparator that charges and discharges storage capacitors to generate output voltages for comparison, allowing motion detection without storing the entire image, thereby reducing memory and computational requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional motion detection stores entire images in memory for comparison, then motion detection accuracy is maintained, but memory size and computational complexity increase significantly
Solution Approach 1:
The patent divides the image processing task into pixel-level operations. Instead of storing and processing entire images, each pixel independently compares its current signal with a stored reference value, enabling motion detection through local differential computation rather than global image comparison
Solution Approach 2:
The patent extracts only the essential motion detection function from full image processing. By using a differential computation unit that compares current pixel signals with stored reference values, the system extracts motion information without requiring storage or processing of complete image data
Solution Approach 3:
The patent changes the parameter being processed from complete image data to differential voltage signals at pixel level. The storage capacitor holds reference voltage levels corresponding to background illumination, and the differential computation unit compares these with current signals to detect motion, transforming the problem from image storage to voltage comparison
2Measurement precision
If pixel signals are amplified and digitized for full image processing, then image quality is preserved, but energy consumption and processing time increase
Solution Approach 1:
The patent applies partial action by performing only the necessary computation for motion detection at pixel level. The differential computation unit compares signals locally without requiring full amplification and digitization of all pixel data, reducing energy consumption while maintaining sufficient signal quality for motion detection
Solution Approach 2:
The patent extracts only the motion detection function from complete image processing. By comparing differential voltages directly at pixel level without full ADC conversion and digital processing, the system achieves motion detection with reduced energy consumption while preserving the essential signal information needed for motion detection
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 enables efficient motion detection by comparing differential image signals at the pixel level, reducing memory size and simplifying computations while maintaining effective motion detection capabilities.
Implementation Method 1
The BJT pixel circuit comprises a photodiode
Implementation Method 2
a BJT, controlled by the photodiode
Implementation Method 3
a first storage capacitor; a second storage capacitor
Data Source
AI summary
An image sensor comprising a BJT pixel circuit, a biasing circuit and a comparator. The BJT pixel circuit comprises a BJT; a charging selection circuit, configured to control a first storage capacitor to be charged in a first reset time and to control a second storage capacitor to be charged to a second reset time; a discharging selection circuit, configured to control the first storage capacitor to be discharged by the BJT in a first exposure time to generate a first output voltage, and to control the second storage capacitor to be discharged by the BJT in a second exposure time to generate a second output voltage; a biasing circuit, configured to provide voltage decreasing and voltage increasing to the second output voltage to generated adjusted images; and a comparator, configured to compare the first output voltage and the adjusted voltages.