CMOS ROIC Multi-Register Bank for Parallax Error Reduction
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Solution Overview
Problem
Conventional digital time delay integration (TDI) scanning array devices using CMOS technology face significant parallax error due to the need for multiple independent TDI arrays and off-chip digital readout circuitry for each spectral band, which can render imagery unusable, especially for larger arrays.
Innovation Solution
The implementation of multiple accumulation registers within a single on-chip CMOS read-out integrated circuit (ROIC) allows for the accumulation and integration of multiple interlaced images, reducing parallax error by using a single accumulation ROIC per detector array and enabling efficient switching between filter bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple independent TDI arrays are used for each spectral band, then spectral imaging capability is improved, but in-track spatial offset increases causing parallax error
Solution Approach 1:
The patent merges multiple TDI arrays for different spectral bands into a single integrated TDI array. Multiple optical bandpass filters are positioned over different regions of the same array, allowing simultaneous capture of multiple spectral bands without the in-track spatial offset that plagues separate arrays. This consolidation eliminates the parallax error between bands while maintaining full spectral imaging capability.
Solution Approach 2:
The single TDI array is designed to perform multiple spectral imaging functions simultaneously. By incorporating multiple optical bandpass filters over different regions of the same array, each region can capture a different spectral band, making the single array universal for multispectral imaging without requiring separate dedicated arrays for each band.
2Adaptability or versatility
If multiple independent TDI arrays are used for each spectral band, then spectral coverage is improved, but device complexity increases
Solution Approach 1:
The patent combines what would traditionally require multiple separate TDI arrays into a single integrated array. By placing multiple optical bandpass filters over different regions of one array, the system achieves multi-spectral coverage with a single device, dramatically reducing complexity while maintaining the ability to capture multiple spectral bands simultaneously.
3Reliability
If conventional digital TDI accumulation is used with off-chip readout circuitry, then signal accumulation is achieved, but temporal offset between bands increases
Solution Approach 1:
The patent replaces the conventional digital TDI accumulation process with on-chip analog accumulation using a capacitor chain. This substitution eliminates the need to completely read out each frame to an accumulator before summing, thereby eliminating the temporal offset between bands. The analog capacitor chain performs continuous accumulation in-phase with image motion, maintaining synchronization across all spectral bands.
4Manufacturing precision
If a filter wheel with single TDI detector is used, then parallax offset is reduced, but acquisition speed decreases
Solution Approach 1:
Instead of sequentially switching filters as in a filter wheel, the patent uses multiple optical bandpass filters positioned simultaneously over different regions of the TDI array. Each region captures a different spectral band in parallel, eliminating the sequential time penalty of filter wheel operation while maintaining minimal parallax offset through the single-array architecture.
Data Source
AI summary
An integrated circuit includes an array of pixels for capturing and processing successive image frames of a moving scene, the array including at least one row of pixels (inputs); and at least one current value register, in which the current value register is configured to store current pixel values captured from the array (inputs). Also included is at least one set of multiple accumulated value registers, in which each accumulated value register is configured to communicate with the current value register. Furthermore, there is included at least one readout register, in which the readout register is configured to communicate with the set of accumulated value registers. A controller is also included for shifting and summing the rows of pixels and outputting a summed column as a time delayed integrated (TDI) signal.