SPAD Pixel Counter Circuit for Motion and Grayscale Detection
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Solution Overview
Problem
Existing light detecting devices lack improved detection performance, particularly in terms of motion and intensity signal detection.
Innovation Solution
A photodetector comprising pixels with SPAD elements and counter circuits that process signals based on the difference in the number of pulses during specific time periods to detect motion and intensity signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional light detecting devices are used, then basic light detection is achieved, but detection performance is insufficient
Solution Approach 1:
The device is divided into multiple pixels, each with independent SPAD elements and counter circuits. This segmentation allows parallel processing of light signals across multiple pixels, improving overall detection performance while maintaining manageable complexity through modular design
Solution Approach 2:
The invention adds a temporal dimension to light detection by measuring photon arrival times and calculating time differences. This transforms the detection from simple intensity measurement to four-dimensional spacetime measurement, significantly improving detection performance for motion and intensity signals
2Measurement precision
If simple counting of light signals is performed, then device complexity is low, but motion and intensity signal detection accuracy is insufficient
Solution Approach 1:
The counter circuits perform preliminary counting of light signals in first and second periods before the final calculation stage. This preliminary action organizes the raw data into manageable counts that can be efficiently processed to extract motion and intensity information
Solution Approach 2:
The system uses feedback by comparing the difference between counts in first and second periods with reference values to determine motion and intensity signals. This feedback mechanism enables accurate detection while maintaining relatively simple circuitry through intelligent signal processing
3Use of energy by moving object
If detection is performed at low illuminance, then energy consumption is reduced, but signal-to-noise ratio deteriorates
Solution Approach 1:
The counter circuits operate in periodic intervals (first period and second period), allowing accumulation of photon counts over time. This periodic sampling at low illuminance conditions improves the signal-to-noise ratio through temporal integration while maintaining low energy consumption by not continuously operating at high power
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 photodetector achieves high detection performance by concurrently obtaining motion and grayscale signals, enhancing accuracy at low illuminance and contrast, and improving signal-to-noise ratio through signal processing and averaging.
Implementation Method 1
a light receiving element configured to receive light
Data Source
AI summary
There is provided a light detecting device including: a pixel comprising a light receiving element; and a pixel circuit comprising a counter circuit and a control circuit. The light receiving element is configured to receive light. The counter circuit is configured to receive a first signal based on an output of the light receiving element. The counter circuit is configured to output a second signal based on a difference between a number of first signals in a first period and a number of first signals in a second period. The control circuit is configured to control the counter circuit.