Flux Rate Unit Cell Focal Plane Array Dynamic Integration
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Solution Overview
Problem
Conventional image capturing devices face limitations in dynamic range due to saturation issues with fixed integration periods and the need for large capacitors and precision charge dump circuits, leading to high power consumption and current spikes.
Innovation Solution
The imaging system integrates a fixed amount of flux over a variable time period using a small integration capacitor and a counter, with a comparator latching the counter value when a threshold voltage is reached, eliminating the need for multibit converters and precision charge dump circuits, and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed integration period is used to accumulate charge, then the circuit operation is simplified, but the dynamic range is limited due to saturation issues
Solution Approach 1:
The patent implements dynamic integration by allowing the integration time to vary for each pixel based on the incident flux intensity. The integration period is extended for low-light pixels and shortened for high-light pixels, enabling the system to adapt to varying light conditions and achieve high dynamic range without saturation.
Solution Approach 2:
The patent changes the integration time parameter dynamically for each pixel based on the measured flux intensity. By adjusting this temporal parameter rather than keeping it fixed, the system can accommodate a wide range of light intensities and achieve high dynamic range imaging capability.
2Adaptability or versatility
If large integration capacitors are used to increase dynamic range, then the flux integration capability is improved, but the device area and power consumption increase
Solution Approach 1:
Instead of using large capacitors to increase dynamic range, the patent uses dynamic integration time adjustment. This allows small capacitors to achieve the same dynamic range effect by integrating charge for longer periods when needed, thereby reducing the required capacitor size and device area.
Solution Approach 2:
The patent replaces the physical approach of using large capacitors with a temporal approach of varying integration time. This substitution of the integration mechanism allows achieving high dynamic range with smaller, more area-efficient components.
3Measurement precision
If precision charge dump circuits are used to maintain accuracy, then the measurement precision is improved, but the power consumption and circuit complexity increase
Solution Approach 1:
The patent extracts and eliminates the need for precision charge dump circuits by using a different approach: direct measurement of integration time. This removes the harmful element (complex charge dump circuitry) while maintaining measurement accuracy through a simpler timing-based method.
Solution Approach 2:
The patent replaces the electrical charge transfer mechanism with a temporal measurement mechanism. By measuring how long it takes to accumulate a fixed charge amount rather than transferring charge precisely, the system achieves the same measurement goal with lower power consumption and simpler circuitry.
4Measurement precision
If multibit analog-digital converters are used to digitize the integrated charge, then the measurement precision is improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent replaces the analog-to-digital conversion process with a direct digital timing measurement. Instead of converting analog charge levels to digital values using complex converters, the system directly measures and records the integration time as a digital value, achieving the same information with simpler circuitry.
Solution Approach 2:
The patent extracts and removes the multibit ADC component from the system by using an alternative measurement approach. The timing-based method eliminates the need for complex analog-to-digital conversion hardware while maintaining the ability to accurately represent flux intensity levels.
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 a high dynamic range imaging system with reduced power requirements and minimized current spikes, while maintaining image quality across varying light intensities.
Implementation Method 1
a photodetector configured to generate a photo-current in response to receiving optical radiation
Implementation Method 2
a first integration capacitor... configured to maintain charge on the integration capacitor corresponding to the photo-current received from the photodetector during an integration period
Data Source
AI summary
According to one aspect, embodiments herein provide a unit cell circuit comprising a photodetector, a first integration capacitor, a first input circuit configured to maintain charge on the integration capacitor corresponding to photo-current received from the photodetector during an integration period, a first comparator coupled to the first integration capacitor and configured to compare a first integration voltage across the first integration capacitor to a first threshold reference voltage, a register coupled to the first comparator, and a counter coupled to the register and configured to repeatedly increment a counter value over the integration period, wherein in response to determining that the first integration voltage is at a certain level in relation to the first threshold reference voltage, the first comparator is further configured to output a first output signal configured to control the register to latch the counter value of the counter.