Infrared Imager Pixel Clamp Circuit for High-Energy Suppression

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Solution Overview

Problem

Digital imaging systems are susceptible to transient energy spikes in harsh environments, leading to blooming and elevated dark current effects, and existing solutions consume large amounts of power or rely on precise tunings, failing to handle a wide range of energy levels effectively.

Innovation Solution

The implementation of a circuit with a photodetector, integration capacitor, amplifier, event detector, and switchable clamp in each optical detector, where the event detector closes the switchable clamp to prevent excessive energy from reaching the integration capacitor during high-energy events, and de-bias protection diodes help maintain pixel bias and prevent de-biasing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing high-energy suppression solutions are implemented, then imaging systems can handle high-energy events, but power consumption increases significantly

Engineering Contradiction:

Improvehigh-energy event toleranceVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The circuit uses the high-energy event signal itself to trigger the suppression mechanism. When a high-energy event is detected, the signal automatically activates the clamp circuit without requiring external power-intensive processing or control systems, achieving self-service high-energy suppression.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The invention employs simple, low-cost circuit elements (clamps, switches, and basic detectors) that provide high-energy suppression through passive or semi-passive mechanisms rather than expensive, power-hungry active suppression systems. The solution accepts that these components are simple and short-lived in terms of complexity, trading component sophistication for power efficiency.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Reliability

If existing high-energy suppression solutions are implemented, then imaging systems can handle high-energy events, but device complexity increases due to precise tuning requirements

Engineering Contradiction:

Improvehigh-energy event toleranceVSAvoidcircuit tuning complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention suppresses high-energy events by changing the electrical state of simple circuit components (clamps and switches) rather than requiring precise tuning of multiple parameters. The approach transforms the problem from one of parameter optimization to one of state control, significantly reducing device complexity.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The invention extracts the high-energy event detection and suppression function into a separate, simple trigger mechanism that operates independently from the main imaging circuitry. This isolation removes the need for complex tuning of the entire imaging system, as only the simple clamp circuit needs to respond to the extracted high-energy signal.

Inventive Principle:

Principle #2Taking out (Extraction)

3Reliability

If existing high-energy suppression solutions are implemented, then imaging systems can handle high-energy events, but they fail to handle a wide range of energy levels effectively

Engineering Contradiction:

Improvehigh-energy event toleranceVSAvoidenergy level range handling

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The clamp circuit is designed to respond to high-energy events across a wide range of energy levels through a single universal mechanism. Rather than requiring different suppression strategies for different energy levels, the invention uses one multi-functional clamp circuit that automatically adapts to various energy levels, achieving universality in high-energy suppression.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution enables imaging systems to be tolerant to high-energy effects, allowing for excellent imaging during harsh conditions while using small, low-power circuits and supporting a wide range of energy levels, with rapid recovery from high-energy events.

Implementation Method 1

a photodetector configured to generate an electrical current based on received illumination

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Data Source

PatentUS11894670B2High-energy suppression for infrared imagers or other imaging devices

Publication Date: 2024.02.06 RAYTHEON CO

AI summary

An apparatus includes a photodetector configured to generate an electrical current based on received illumination. The apparatus also includes an integration capacitor configured to integrate the electrical current and generate an integrator voltage. The apparatus further includes an amplifier configured to control a transistor switch coupled in series between the photodetector and the integration capacitor. The apparatus also includes an event detector configured to sense a high-energy event affecting the photodetector. In addition, the apparatus includes a switchable clamp coupled across inputs of the amplifier, where the event detector is configured to close the switchable clamp in response to sensing the high-energy event.