Threshold-Stopped Counters for Low-Power High-Dynamic-Range Pixels

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Solution Overview

Problem

Digital pixel architectures face issues with flux-dependent power consumption, leading to high current draws that can damage components and limit their use in certain applications, while residue pixel architectures have lower dynamic range.

Innovation Solution

A digital pixel architecture that includes a capacitor, comparator, and counters to manage power consumption by stopping counting when a threshold is reached, allowing for flux-dependent integration time scaling and achieving high dynamic range with reduced power usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a pure digital pixel architecture is used to achieve high dynamic range, then dynamic range is improved, but power consumption increases and current draw becomes extremely high

Engineering Contradiction:

Improvedynamic rangeVSAvoidpower consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic integration time scaling where the integration time is adjusted based on the measured flux level. When flux is high, integration time is reduced proportionally to maintain signal within the dynamic range while reducing power consumption. This dynamic adaptation allows the system to achieve high dynamic range without the extremely high current draws of pure digital architectures.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the integration time parameter based on measured flux conditions. By scaling integration time inversely with flux level (t_int = T_max / (1 + k*Φ)), the system adapts its operating parameters to maintain optimal dynamic range while controlling power consumption across varying illumination conditions.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If a pure digital pixel architecture is used to achieve high dynamic range, then dynamic range is improved, but current draw becomes extremely high which can damage components

Engineering Contradiction:

Improvedynamic rangeVSAvoidcurrent draw

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system dynamically adjusts integration time based on measured flux to prevent excessive current draw. By reducing integration time when flux is high, the system maintains signal levels within safe operating ranges while preserving dynamic range measurement capability, thus avoiding component damage.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback control where the measured flux level is used to adjust the integration time for subsequent measurements. This feedback mechanism ensures that the system responds to high flux conditions by reducing integration time, thereby controlling current draw and preventing harmful effects while maintaining accurate dynamic range measurement.

Inventive Principle:

Principle #23Feedback

3Use of energy by moving object

If a residue digital pixel architecture is used to avoid flux-dependent power consumption, then power consumption is reduced, but dynamic range decreases

Engineering Contradiction:

Improvepower consumptionVSAvoiddynamic range

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent implements dynamic integration time scaling that allows residue digital pixel architecture to achieve high dynamic range by extending integration time for low flux conditions while maintaining reduced power consumption. This dynamic adaptation compensates for the typically lower dynamic range of residue architectures.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

By changing the integration time parameter based on flux conditions, the system enables residue digital pixel architecture to achieve high dynamic range performance. The scaled integration time allows sufficient signal accumulation for low flux scenes while maintaining the power consumption advantages of residue architecture.

Inventive Principle:

Principle #35Parameter changes

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 architecture achieves similar or higher dynamic range with significantly reduced power consumption, enabling smaller pixel area utilization and preventing component damage.

Implementation Method 1

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

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

a capacitor configured to be charged by the electrical current and generate a voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS12432475B2Digital pixel architecture supporting low power and high dynamic range operation having a counter that stops counting pulses in response to detecting a voltage on a capacitor exceeding a threshold

Publication Date: 2025.09.30 RAYTHEON CO

AI summary

A system includes a focal plane array having multiple pixel circuit elements. Each pixel circuit element includes a photodetector configured to generate an electrical current based on received illumination. Each pixel circuit element also includes a capacitor configured to be charged by the electrical current and generate a voltage. Each pixel circuit element further includes a controller configured to sense whether the voltage on the capacitor exceeds a threshold during a sampling period. In addition, each pixel circuit element includes a timer configured to generate an estimate or measure of an amount of time within the sampling period during which the voltage on the capacitor does not exceed the threshold.