Infrared Sensor ROIC Bias Correction for Pixel Non-Uniformity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Infrared sensors with micro-bolometer focal plane arrays face non-uniformity issues due to varying bolometer resistance, leading to limited amplification and reduced scene dynamic range, causing signal saturation and reduced detection characteristics.
Innovation Solution
A read-out integrated circuit (ROIC) with a cell array, level generator, and correction units that adjust bias voltages for each bolometer to correct resistance non-uniformity, using a control unit to set bias levels and store resistance correction values for optimal signal integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If bias voltage is applied to bolometers to generate signal current, then detection sensitivity is improved, but resistance non-uniformity between pixels increases causing signal saturation
Solution Approach 1:
The patent applies parameter changes by adjusting the bias voltage level for each pixel based on its specific resistance characteristics. The NUC unit modifies the bias voltage parameter to compensate for resistance non-uniformity, allowing each pixel to operate at its optimal detection sensitivity without causing signal saturation. This is achieved by storing correction values in a lookup table and selecting appropriate bias levels dynamically.
2Measurement precision
If amplification factor is increased to improve signal current, then detection characteristics are enhanced, but non-uniformity between pixels is amplified
Solution Approach 1:
The patent implements local quality by applying individualized bias voltage corrections to each pixel based on its specific resistance characteristics. Instead of using a uniform amplification factor for all pixels, the system tailors the bias voltage level to each pixel's local properties, thereby enhancing detection characteristics while preventing the amplification of non-uniformity artifacts.
3Measurement precision
If DC bias current is eliminated using skimming cell, then signal current extraction is improved, but circuit complexity increases
Solution Approach 1:
The patent uses an intermediary approach by introducing the NUC unit as a mediator between the bolometer array and the signal processing circuitry. This NUC unit acts as an intermediate correction layer that adjusts bias voltages before signals are fully processed, enabling effective DC bias current elimination and signal extraction while managing circuit complexity through a modular correction architecture.
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
Minimizes pixel non-uniformity, maximizes scene dynamic range, and enhances detection characteristics by improving the amplification factor, resulting in more accurate and reliable infrared imaging.
Implementation Method 1
micro-bolometers are resistance thermometers used to measure an infrared ray
Implementation Method 2
when an infrared ray is applied, temperature increases and electric resistance changes
Implementation Method 3
temperature increases and electric resistance changes as a detection element
Data Source
AI summary
A signal detecting circuit of an infrared sensor includes: a cell array in which bolometers sensing infrared rays and outputting signal currents are arranged in an N×M format; a level generator that outputs a plurality of bias voltages corresponding to a plurality of bias levels; N resistor non-uniformity correcting circuits that are located in a column direction of the cell array and supply different bias voltages to each of the bolometers; M resistor non-uniformity correcting circuits that are located in a row direction of the cell array and supply different bias voltages to each of the bolometers; a control unit that sets a bias voltage level of each resistor non-uniformity correcting circuit to correct the resistor non-uniformity of the cell array; and N integrators that integrate the signal currents output from the cell array.