Capacitive Fingerprint Sensor Using Segmented Signal Lines
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Solution Overview
Problem
Conventional capacitive fingerprint sensors require small IC chips to reduce production costs, but these are insufficient for capturing entire fingerprint images with high resolution, necessitating complex additional technologies for rapid and correct recognition.
Innovation Solution
A capacitive touch panel with M signal transmitting lines and N signal receiving lines, where at least one pitch is greater than or equal to the minimum on-center spacing, allowing for the transmission and reception of charge/discharge signals to generate characteristic values forming a matrix representing the fingerprint information, reducing the need for large semiconductor IC chips and enabling high-quality fingerprint recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a small pitch capacitive sensor unit is used to capture high resolution fingerprint images, then measurement precision is improved, but device complexity and production cost increase due to large IC chip size
Solution Approach 1:
The fingerprint sensing area is divided into multiple neighboring regions, each sensed by a combination of signal transmitting lines and signal receiving lines. The characteristic value matrix is constructed by processing signals from these segmented regions, enabling high-resolution fingerprint capture without requiring a uniformly dense sensor array across the entire chip.
Solution Approach 2:
The patent transitions from a two-dimensional sensor array to a three-dimensional sensing approach by utilizing multiple layers of signal transmitting lines and signal receiving lines. This layered structure enables high-resolution fingerprint sensing with reduced pitch requirements, as the additional spatial dimension provides more sensing points without proportionally increasing chip area.
2Measurement precision
If a small pitch capacitive sensor unit is used to capture high resolution fingerprint images, then measurement precision is improved, but manufacturing cost increases due to large IC chip size
Solution Approach 1:
The fingerprint sensing area is divided into multiple neighboring regions, each sensed by a combination of signal transmitting lines and signal receiving lines. The characteristic value matrix is constructed by processing signals from these segmented regions, enabling high-resolution fingerprint capture without requiring a uniformly dense sensor array across the entire chip.
Solution Approach 2:
The patent changes the pitch parameter of the capacitive sensor unit from small (conventional) to larger dimensions. By using larger pitch values for signal transmitting lines and signal receiving lines, the IC chip size is reduced, lowering production costs while maintaining fingerprint recognition capability through the segmented sensing approach.
3Measurement precision
If a larger IC chip is used to cover the fingerprint area with sufficient resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent transitions from a two-dimensional sensor array to a three-dimensional sensing approach by utilizing multiple layers of signal transmitting lines and signal receiving lines. This layered structure enables high-resolution fingerprint sensing with reduced pitch requirements, as the additional spatial dimension provides more sensing points without proportionally increasing chip area.
Solution Approach 2:
The fingerprint sensing area is divided into multiple neighboring regions, each sensed by a combination of signal transmitting lines and signal receiving lines. The characteristic value matrix is constructed by processing signals from these segmented regions, enabling high-resolution fingerprint capture without requiring a uniformly dense sensor array across the entire chip.
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 allows for high-quality fingerprint recognition at a lower cost by capturing entire fingerprint images with improved electrical properties and reduced production costs, without the need for large semiconductor IC chips, while maintaining high resolution and accuracy.
Implementation Method 1
a capacitive touch panel to be approached or touched with an object with the biological feature includes M signal transmitting lines and N signal receiving lines
Data Source
AI summary
A biological feature-sensing device for acquiring biological feature information by sensing a biological feature is provided. The biological feature-sensing device includes a capacitive touch panel and a control circuit. The capacitive touch panel includes signal transmitting lines and signal receiving lines. A first pitch of the signal transmitting lines or a second pitch of the signal receiving lines is greater than or equal to a minimum on-center spacing of the biological feature. The control circuit receives first and second voltage signals through two sets of signal receiving lines in response to first and second charge/discharge signals transmitted through two sets of signal transmitting lines, and generates a characteristic value according to the first and second voltage signals. Many characteristic values corresponding to different combinations of the signal transmitting lines and signal receiving lines are generated accordingly to form a characteristic value matrix representing the biological feature information.