Shared-Heating Thermal Pattern Sensor for High-Resolution Detection
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Solution Overview
Problem
Existing thermal pattern sensors, particularly fingerprint detectors, face challenges in achieving high resolution while using low-cost printing techniques due to the incompatibility of these methods with the required pixel spacing and resolution, leading to issues with signal detection and image processing when the finger and sensor are at the same temperature or when static acquisition occurs.
Innovation Solution
A thermal pattern sensor design where each electrically conductive portion acts as a heating element for multiple adjacent lines of pixels, allowing for reduced resolution requirements in the conductive portions and enabling printing techniques to be used, while maintaining effective heating and signal detection through Joule effect heating and pyroelectric capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If each pixel has its own heating element for active thermal sensing, then detection accuracy is improved, but manufacturing complexity and cost increase due to high resolution requirements
Solution Approach 1:
The patent merges the heating function for multiple adjacent pixel lines into a single shared heating element. Specifically, one heating element positioned between substrate 104 and pyroelectric layer 106 heats multiple lines of pixels (e.g., lines 102.1 and 102.2) simultaneously, eliminating the need for separate heating elements for each pixel while maintaining effective thermal sensing across all heated pixels.
Solution Approach 2:
The shared heating element serves multiple functions: it provides active heating for multiple lines of pixels simultaneously, enabling cost-effective manufacturing through printing techniques while maintaining detection accuracy. The heating element positioned between the substrate and pyroelectric layer acts as a universal thermal source for adjacent pixel lines.
2Ease of manufacture
If printing techniques are used to reduce manufacturing cost, then ease of manufacture is improved, but pixel resolution and signal detection quality deteriorate
Solution Approach 1:
The patent combines multiple pixel lines under a single heating element, allowing the heating element to have lower resolution requirements than individual pixels. This enables the use of printing techniques for fabricating the heating element while maintaining sufficient thermal control for high-quality signal detection across multiple pixel lines.
Solution Approach 2:
The heating element is positioned in a different spatial dimension (between substrate and pyroelectric layer) than the pixel readout electrodes, allowing it to serve multiple pixel lines without requiring precise alignment with each individual pixel. This dimensional separation enables lower resolution manufacturing for the heating element while maintaining high resolution for pixel detection.
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 design allows for the production of thermal pattern sensors with improved pixel resolution and reduced manufacturing costs, enabling effective detection of thermal patterns by allowing each conductive portion to heat multiple lines of pixels, thus enhancing signal quality and reducing the need for cooling periods between readings.
Implementation Method 1
each capable of heating by means of the Joule effect, independently of the other electrically conductive portions, of the portions of pyroelectric material
Implementation Method 2
pyroelectric elements, diodes, thermistors or any other temperature-sensitive elements which can convert a temperature variation into an electrical potential or current variation
Data Source
AI summary
A thermal pattern sensor is provided, including a matrix of several lines and columns of pixels, each pixel including at least one pyroelectric capacitance formed by at least one portion of pyroelectric material arranged between a lower electrode and an upper electrode; wherein one of the lower and upper electrodes forms a reading electrode of the pixels; and a plurality of electrically conductive portions, each being configured for Joule effect heating, independently of other portions of the plurality, of the at least one portion of pyroelectric material of the at least one pyroelectric capacitance of pixels of at least two adjacent lines of pixels associated with the each electrically conductive portion, and each being arranged facing at least a part of a surface of the reading electrode of each of the pixels of the at least two adjacent lines of pixels associated with the each electrically conductive portion.