Light Sensing Apparatus Automatic Gain Control Ghost Image Suppression
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Solution Overview
Problem
Light sensing devices used in seekers for guiding smart munitions face issues with sensitivity, as strong signals can generate ghost images in unintended pixels, leading to false target detection, especially when approaching the intended target.
Innovation Solution
The implementation of an automatic gain control (AGC) circuit that adjusts the sensitivity of light sensing pixels by diffusing additional light or controlling current injection, raising the noise floor to prevent false triggering, thereby reducing sensitivity to strong signals and minimizing ghost image detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitivity of light sensing pixels is increased to detect faint laser designating signals, then the detection capability for weak signals is improved, but ghost images are generated in unintended pixels when strong signals are received, leading to false target detection
Solution Approach 1:
The patent applies preliminary anti-action by proactively raising the noise floor before strong signals can cause ghost images. The system continuously monitors signal strength and preemptively adjusts the noise floor level to prevent false triggering in unintended pixels, rather than attempting to correct ghost images after they occur.
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting the noise floor parameter based on incoming signal conditions. When strong signals are detected, the noise floor is raised to suppress ghost image generation; when weak signals are present, the noise floor is lowered to maintain detection sensitivity. This adaptive parameter adjustment resolves the contradiction between detecting weak signals and preventing ghost images.
2Measurement precision
If the gain of light sensing pixels is increased to enhance signal detection, then the ability to detect laser designating signals at distance is improved, but the dynamic range is exceeded when approaching the target, causing false detections
Solution Approach 1:
The patent applies dynamics by making the noise floor adaptive rather than fixed. The system continuously adjusts the noise floor level in real-time based on the strength of incoming signals, allowing the same light sensing pixels to operate effectively across a wide dynamic range from long-distance weak signal detection to close-range strong signal detection without false detections.
Solution Approach 2:
The patent implements feedback by monitoring the output signals from light sensing pixels and using this information to adjust the noise floor level. When strong signals cause unintended pixel triggering, the feedback loop increases the noise floor to suppress false detections, and when weak signals need detection, the noise floor is reduced to enhance sensitivity.
3Measurement precision
If the sensitivity threshold is lowered to detect weaker signals, then the detection range is extended, but the noise floor causes false triggering in unintended pixels
Solution Approach 1:
The patent resolves this contradiction by making the noise floor a dynamic parameter rather than a fixed value. The system adjusts the noise floor level based on signal conditions, allowing the sensitivity threshold to remain low for detecting weak signals while the noise floor is simultaneously raised to prevent false triggering, thereby maintaining both detection sensitivity and reliability.
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 AGC circuit effectively reduces false detections by setting a higher noise floor, ensuring that only the intended target is sensed while suppressing unintended targets, thereby improving the accuracy of the guidance system.
Implementation Method 1
the AGC circuit includes a light emitting device, such as an arrangement of one or more light emitting diodes (LEDs) and one or more diffusing optics, to diffuse additional light to the light sensing pixels
Implementation Method 2
Each pixel includes a light detecting sensor to detect a triggering level of incoming light from a corresponding portion of a scene
Data Source
AI summary
A light sensing apparatus includes: an arrangement of light sensing pixels, one or more pixels each associated with a noise floor and able to detect a triggering level of incoming light above the noise floor from a corresponding portion of a scene; readout circuitry to process and reset the triggering pixels; and an automatic gain control (AGC) to raise the noise floor of one or more pixels. Sometimes, the light sensing apparatus is part of a seeker that includes control circuitry to dynamically control the AGC to raise the noise floor of one or more pixels by an adjustable amount that varies in relation to the distance between the seeker and an intended target. Sometimes, the control circuitry dynamically controls the AGC in response to a concurrent triggering of two or more triggering pixels. or in response to a gain schedule corresponding to guiding the seeker to the intended target.