Fingerprint Detection Circuit Segmentation for Miniaturization
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Solution Overview
Problem
Conventional capacitive fingerprint identification chips face a challenge in miniaturization, as the area proportion of effective pixels decreases due to the non-proportional reduction of the power ring area, leading to degraded performance in miniaturized designs.
Innovation Solution
The fingerprint detection circuit incorporates a pixel region with a first and second pixel region, where the second pixel region is on the periphery, and a power grid is arranged below to provide a driving electrical signal, ensuring consistent capacitances of the first pixel electrodes to ground, thus maintaining the area proportion of effective pixels even when miniaturized.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the dimension of the capacitive fingerprint identification chip is reduced, then the chip size is miniaturized, but the area proportion of effective pixels in the pixel region is decreased
Solution Approach 1:
The pixel region is divided into a first pixel region containing first pixels and a second pixel region containing second pixels. The second pixel region is arranged on the periphery of the first pixel region. This segmentation allows the effective first pixels to occupy a larger proportion of the total pixel region area, as the second pixels serve as auxiliary elements that do not compromise the effective sensing area proportion during miniaturization.
Solution Approach 2:
The power grid is moved from a conventional periphery arrangement to a position below the pixel region. This dimensional repositioning allows the power supply function to be separated from the pixel plane, enabling more efficient use of the pixel region area and maintaining a higher proportion of effective pixels when the chip is miniaturized.
2Area of stationary object
If the area of the pixel region is reduced, then the chip is miniaturized, but the area occupied by the power ring is not proportionally decreased
Solution Approach 1:
The power grid is repositioned from the periphery of the pixel region to below the pixel region. This dimensional change separates the power supply structure from the pixel plane, allowing the power grid to occupy space that does not compete with the pixel region area. As a result, when the pixel region area is reduced for miniaturization, the power grid area does not proportionally decrease, maintaining efficient power supply without compromising pixel density.
3Volume of moving object
If the area proportion of effective pixels is decreased, then miniaturization is achieved, but the detection accuracy is degraded
Solution Approach 1:
The pixel region is segmented into first pixels for effective fingerprint detection and second pixels arranged on the periphery. This segmentation ensures that the first pixels maintain a high area proportion within the pixel region, preserving detection accuracy. The second pixels serve auxiliary functions without compromising the effective sensing area, allowing miniaturization without degrading detection performance.
Solution Approach 2:
The second pixels are configured to cause capacitances of the pixel electrodes of the first pixels to ground to be equal to each other. This equipotential configuration ensures uniform detection characteristics across all first pixels, maintaining consistent detection accuracy even when the overall chip size is reduced.
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 configuration enhances the area proportion of effective pixels, improves detection accuracy, and reduces interference, ensuring the capacitive fingerprint identification chip's performance is maintained despite miniaturization.
Implementation Method 1
detect a coupling capacitance formed between the pixel electrodes of the plurality of first pixels and a biological tissue
Implementation Method 2
the power source grid being configured to provide a driving electrical signal for pixel electrodes of the plurality of first pixels and pixel electrodes of the plurality of second pixels
Data Source
AI summary
A fingerprint detection circuit includes: a pixel region and a power grid. The pixel region includes a first pixel region and a second pixel region. The second pixel region is arranged on a periphery of the first pixel region, the first pixel region is provided with a plurality of first pixels, and the second pixel region is provided with a plurality of second pixels. The power grid is arranged below the pixel region, and configured to provide a driving electrical signal for pixel electrodes of the plurality of first pixels and pixel electrodes of the plurality of second pixels, to detect a coupling capacitance formed between the pixel electrodes of the plurality of first pixels and a biological tissue and to cause, via the plurality of second pixels, capacitances of the pixel electrodes of the plurality of first pixels to ground to be consistent.