Capacitive Image Sensor Array Merging Elements for Signal Strength
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Solution Overview
Problem
Existing capacitive image sensors face challenges in effectively sensing biometric images, such as fingerprint images, through dielectric layers, due to reduced signal levels and signal-to-noise ratios, especially when the sensor elements are separated by increasing thicknesses of materials like flex material or glass.
Innovation Solution
The proposed solution involves a sensing circuit and method that utilize a plurality of transmitting or receiving elements forming a grid array, with a controller to provide or receive probing signals simultaneously across multiple elements, enhancing the effective area for signal transmission or reception. This includes a noise reduction circuit using differential amplification to cancel out noise, allowing for improved signal acquisition and noise reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the thickness of dielectric layers between sensor elements and biometric features is increased, then protection and structural integrity are improved, but signal level and signal-to-noise ratio deteriorate
Solution Approach 1:
The patent combines multiple transmitting or receiving elements into groups that operate simultaneously to form a single effective pixel location. This merging of elements increases the effective sensing area and aggregates the signal strength, thereby improving the signal level and signal-to-noise ratio while maintaining protection through dielectric layers
2Measurement precision
If multiple transmitting or receiving elements are used to increase effective area, then signal level is improved, but device complexity increases
Solution Approach 1:
The patent segments the sensor array into groups of transmitting or receiving elements, where each group functions as a single pixel location. This segmentation allows simultaneous operation of multiple elements while managing complexity through organized grouping and coordinated control
3Reliability
If dielectric layers of increasing thickness are used, then protection and structural integrity are improved, but signal-to-noise ratio deteriorates
Solution Approach 1:
By combining multiple elements into groups that operate simultaneously, the patent increases the effective signal strength that can penetrate through thicker dielectric layers, thereby maintaining signal-to-noise ratio even when protection layers are thicker
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 approach increases the signal level and signal-to-noise ratio, enabling effective biometric imaging through dielectric layers without compromising resolution, even with increased thicknesses between sensor elements and the biometric feature.
Implementation Method 1
capacitive image sensing... a capacitive image sensor, such as for sensing biometrics
Implementation Method 2
a noise reduction circuit using differential amplification to cancel out noise
Data Source
AI summary
A sensing circuit and method is disclosed, which may comprise a plurality of transmitting or receiving elements each defining a pixel location defined by a gap between the respective one of the plurality of transmitting or receiving elements and a single element of the opposing type to the respective transmitting or receiving element, and a controller configured to provide or receive a probing signal to or from a group of at least two of the plurality of transmitting or receiving elements, at the same time, thereby increasing the effective area providing the transmitting of or the receiving of the probing signal for each pixel location imaged. The group of transmitting or receiving elements may form a symmetric pattern, which may be centered on the pixel location. The plurality of transmitting or receiving elements may form at least one linear pixel array with the respective single receiving or transmitting element.