Ultrasonic Fingerprint Scanner Array Eliminates Mechanical Scanning
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Solution Overview
Problem
Ultrasonic fingerprint scanning technologies are slower than optical systems due to the need for mechanical scanning of each pixel individually, despite providing superior detail and being immune to contaminants like grease and dirt.
Innovation Solution
A fingerprint scanner using a plane wave ultrasonic pulse generator, an ultrasonic wave manipulation device such as a lens or mirror, and an image generator to alter and detect ultrasonic energy reflected from the finger, allowing for the creation of a fingerprint image without mechanical scanning of each pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a two-axis mechanical scanning apparatus is used to collect ultrasonic image information pixel by pixel, then measurement precision is improved, but productivity deteriorates
Solution Approach 1:
The patent replaces the mechanical scanning apparatus with an array of ultrasonic transducers that can simultaneously collect image information from multiple pixels. This substitution eliminates the need for mechanical movement while maintaining high measurement precision through the array's ability to capture detailed ultrasonic reflections from different positions concurrently.
Solution Approach 2:
The patent divides the ultrasonic imaging function into multiple independent transducer elements arranged in an array. Each transducer element can independently collect image information from a specific region, allowing parallel data acquisition that dramatically improves productivity while maintaining the measurement precision of individual elements.
2Productivity
If a large area detector array is used to improve image collection speed, then productivity is improved, but device complexity increases
Solution Approach 1:
The patent implements a hierarchical structure where a large-area detector array is organized into smaller sub-arrays or groups. This nesting approach allows the system to manage complexity by processing data from smaller units while collectively achieving large-area coverage, thereby improving productivity without proportionally increasing overall device complexity.
Solution Approach 2:
The patent extends the detector array in multiple spatial dimensions to cover large areas. By arranging transducers in a two-dimensional grid pattern rather than a single line, the system achieves area-proportional productivity improvement while distributing the complexity across organized spatial positions that can be systematically addressed and controlled.
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 method enables faster image creation of fingerprints with superior detail, overcoming the speed limitations of traditional ultrasonic scanning systems while maintaining immunity to contaminants.
Implementation Method 1
The ultrasound method employs a piezoelectric transducer that sends a sound wave or pulse through an ultrasonic transmitting media
Implementation Method 2
The pulse is then partially reflected back at each media interface. The reflected pulse is received by the transducer
Implementation Method 3
Each lens may refract the ultrasonic energy so as to focus the ultrasonic energy of the reflected plane wave onto an array element
Data Source
AI summary
Some disclosed devices may include a thin-film transistor (TFT) substrate, an electret film and an array of addressable pixels electrically connected to the TFT substrate. The array of addressable pixels may be an array of electrodes proximate a first side of the electret film. The electrodes maybe capable of coupling charge from the electret film to the TFT substrate in response to an acoustic wave.