Infrared Image Sensor Noise Suppression via Periodic Switching
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Solution Overview
Problem
Existing infrared image sensors face challenges in effectively suppressing noise in infrared imaging systems, particularly in civilian applications such as mobile devices and wearable technology, where noise interference can degrade image quality.
Innovation Solution
The proposed infrared image sensor incorporates a noise suppression circuit that switches correspondence between bolometer cells and reference analog values at unit time intervals, and repeats this switching at image time intervals longer than the unit time, integrating output analog values before and after switching to reduce noise, and utilizes a multiplexer to provide infrared image values to an AD converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a noise suppression circuit switches correspondence between bolometer cells and reference analog values at unit time intervals, then noise is reduced by averaging and moving it to an unused frequency range, but device complexity increases due to additional switching and integration circuits
Solution Approach 1:
The noise suppression circuit performs periodic switching of the correspondence between bolometer cells and reference analog values at unit time intervals. This periodic switching moves noise to an unused frequency range and enables averaging over multiple periods, effectively reducing noise while maintaining a systematic approach to signal processing
Solution Approach 2:
The front-end analog circuit acts as an intermediary between the bolometer cells and the AD converter. It includes integration circuits that collect and process output analog values from multiple bolometer cells, performing averaging operations that suppress noise before the signals are converted to digital form
2Measurement precision
If the front-end analog circuit integrates output analog values before and after switching to reduce noise, then measurement precision improves, but loss of time increases due to extended integration periods
Solution Approach 1:
The system uses periodic switching at unit time intervals with integration periods that are multiples of these unit intervals. By integrating over complete switching cycles rather than continuous periods, the system achieves noise reduction through averaging while minimizing the total time required, as the integration is synchronized with the periodic switching pattern
Solution Approach 2:
The noise suppression circuit performs preliminary switching and integration operations at unit time intervals before the final image data is captured. By pre-processing the analog signals through multiple rapid switching cycles and averaging them in advance, the system reduces noise before the main image acquisition, thereby improving measurement precision without significantly extending the overall imaging time
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 significantly reduces noise in acquired infrared images by averaging and moving noise to an unused frequency range, enhancing image quality for civilian applications like mobile devices and wearable technology.
Implementation Method 1
An existing infrared image sensor, which is used to see an object, even in a dark environment, using infrared light radiated by the object
Data Source
AI summary
An infrared image sensor includes: a plurality of reference circuits configured to provide a plurality of reference analog values to a plurality of bolometer cells, respectively; a front-end analog circuit configured to collect a plurality of output analog values according to the plurality of reference analog values; and a noise suppression circuit configured to switch a correspondence between the plurality of bolometer cells and the plurality of reference analog values at unit time intervals.