Pixel Circuit Switching for Higher-Resolution Event Imaging
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Solution Overview
Problem
Conventional pixel circuits in solid-state imaging devices for event detection, such as dynamic vision sensors, face limitations in enhancing temporal resolution and reducing information loss, particularly in applications requiring high dynamic range and low-light performance.
Innovation Solution
A pixel circuit design that includes a photoreceptor circuit block generating a photoreceptor signal, an analog-to-digital converter stage with two inputs for comparing signals with threshold voltages, and an electronic switch assembly to sequentially pass the photoreceptor signal to multiple inputs, decoupling light intensity sampling from event information reading, allowing for increased temporal resolution and reduced information loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single photoreceptor circuit block is used to generate photoreceptor signals, then device complexity is reduced, but temporal resolution is limited because the same circuit must sequentially serve multiple conversion elements
Solution Approach 1:
The pixel array is divided into multiple pixel circuits, each containing its own photoreceptor circuit block and analog-to-digital converter stage. This segmentation allows parallel processing of photoreceptor signals from different conversion elements, thereby improving temporal resolution while maintaining reasonable device complexity through modular design
Solution Approach 2:
The patent introduces a temporal dimension to the signal processing by implementing sequential operation modes within each pixel circuit. The analog-to-digital converter stage can sequentially process signals from different conversion elements at different time points, effectively increasing temporal resolution without requiring simultaneous multiple conversion operations that would greatly increase complexity
2Loss of information
If the photoreceptor signal is read out immediately after generation, then information loss is reduced, but the system cannot detect multiple events occurring in rapid succession because the readout process takes time
Solution Approach 1:
The photoreceptor signal is generated and held in the photoreceptor circuit block in readiness before the analog-to-digital converter stage is activated. This preliminary action allows the signal to be ready for immediate conversion when the readout operation begins, reducing information loss while enabling the system to quickly move to the next event detection
Solution Approach 2:
The pixel circuit operates in periodic cycles, alternating between signal generation/holding mode and readout/conversion mode. During each cycle, the system can detect and hold multiple events, then read them out in sequence. This periodic operation allows high event detection rates while maintaining complete information about each event
3Speed
If multiple analog-to-digital converter stages are used to process signals from multiple conversion elements simultaneously, then temporal resolution is improved, but device complexity and power consumption increase significantly
Solution Approach 1:
Multiple pixel circuits share common readout circuitry and control logic at higher levels of the system hierarchy. While each pixel circuit has its own analog-to-digital converter stage for local processing, the overall system merges readout operations and data collection to reduce total device complexity and power consumption compared to fully parallel independent converters
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 enhances temporal resolution and reduces the probability of information loss by enabling the detection of changes in light intensity before previous events are retrieved, improving the performance of solid-state imaging devices in dynamic environments.
Implementation Method 1
a photoreceptor circuit block that is configured to generate a photoreceptor signal, wherein a voltage level of the photoreceptor signal may depend on the intensity of light detected in a photoelectric conversion element
Data Source
AI summary
A pixel circuit (300) includes a photoreceptor circuit block (PR) configured to generate a photoreceptor signal. An analog-to-digital converter stage (500) is configured to compare a first input photoreceptor signal with at least one first threshold voltage and to compare a second input photoreceptor signal with at least one second threshold voltage. An electronic switch assembly (310) is configured to pass the photoreceptor signal to the first comparison in a first operating state and to pass the photoreceptor signal to the second comparison in a second operating state.