Dynamic Vision Sensor Pulsed Light Pattern Capture
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Solution Overview
Problem
Pulsed image capturing systems face challenges in high ambient illumination environments due to saturation and noise issues, requiring significant image processing to separate pulsed light patterns from ambient light, which increases system complexity and power consumption.
Innovation Solution
A pulsed image capturing system utilizing a dynamic vision sensor (DVS) with a synchronized global reset and hold mechanism, where a global reset signal sets a reference illumination level, and a global hold signal locks illumination change events, allowing for clean extraction of pulsed light pattern reflections without additional image processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a CMOS image sensor is used to capture pulsed light patterns, then the system can capture images, but ambient light causes saturation and noise that make pattern detection difficult
Solution Approach 1:
The patent employs a dynamic vision sensor (DVS) that operates differently from traditional CMOS sensors. Instead of capturing static frames, the DVS dynamically detects changes in illumination levels at each pixel, generating event signals only when light intensity changes occur. This dynamic operation allows the system to respond selectively to pulsed light patterns while ignoring constant ambient light, thereby improving measurement precision without being affected by ambient light saturation.
Solution Approach 2:
The system uses periodic pulsed light illumination combined with periodic reset and hold signals to the DVS. The pulsed light source emits light in periodic pulses, and the DVS is synchronized with these pulses through periodic reset signals (to set reference levels) and hold signals (to capture illumination changes). This periodic coordination between light pulsing and sensor operation enables precise detection of pulsed light patterns while filtering out non-periodic ambient light variations.
2Measurement precision
If traditional image processing methods are used to separate pulsed light from ambient light, then pattern extraction is possible, but system complexity and power consumption increase significantly
Solution Approach 1:
The patent extracts only the relevant information at the sensor level by generating event signals that represent illumination changes. Instead of capturing complete images and performing complex post-processing to separate pulsed light from ambient light, the DVS extracts only the changes in illumination directly at each pixel. This extraction of essential information (illumination changes) at the sensing stage eliminates the need for complex image processing algorithms, thereby reducing device complexity while maintaining accurate pulsed light pattern detection.
3Measurement precision
If the pulsed light duration is increased to improve signal strength, then detection sensitivity improves, but ambient light saturation worsens
Solution Approach 1:
The system implements feedback through synchronized control between the pulsed light source and the DVS operation. The reset signal to the DVS is timed to coincide with the start of each light pulse, establishing a reference level just before the pulse arrives. The hold signal is timed to capture the illumination change during the pulse. This feedback-based synchronization ensures that the sensor is in the correct state to detect the pulse with maximum sensitivity while the short pulse duration prevents ambient light saturation.
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 system effectively captures pulsed light patterns while suppressing ambient light and scene content, reducing noise and power consumption, and enabling binary image capture with minimal processing requirements.
Implementation Method 1
The plurality of pixels are configured to sense an amount of light from the pulsed light pattern reflected by the external object and output event signals
Data Source
AI summary
A pulsed image capturing system includes a pulse generation circuit, a dynamic vision sensor (DVS), and a DVS scanning and readout circuit. A global reset signal is transmitted to pixels of the DVS to set a reference illumination level for the pixels, and then a pulsed light pattern is generated. A global hold signal is transmitted to the pixels, after the pulsed light pattern is generated, to hold an illumination change event indicating a change with respect to the reference illumination level. A DVS scanning and readout operation is performed on event signals received from the pixels, after the global hold signal is transmitted to the pixels. A reflection of the pulsed light pattern is extracted from the DVS output after cleaning artifacts from the DVS output without additional image processing.