Piezoelectric Fingerprint Sensor Pixel Structure for Power Reduction
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Solution Overview
Problem
Existing sensing devices face challenges in achieving high accuracy and security, are difficult to downsize, and struggle with large area sensing due to light source requirements and component limitations, while also experiencing power consumption issues and signal delay problems.
Innovation Solution
A sensing device with a pixel structure incorporating a transducer, piezoelectric material layer, and transistors that use DC voltages for driving and sensing, allowing for efficient ultrasonic wave generation and detection, enabling high accuracy, security, and reduced power consumption, and facilitating downsizing and large area sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If typical sensing devices use light sources and relevant components, then sensing operations can be performed, but device downsizing becomes difficult
Solution Approach 1:
The patent replaces optical components (light sources) with piezoelectric transducers that generate and detect ultrasonic waves mechanically. This substitution eliminates the need for light sources and related optical components, enabling device downsizing while maintaining sensing functionality through ultrasonic wave-based touch detection
Solution Approach 2:
The piezoelectric transducer serves multiple functions: it acts as both a transmitter (generating ultrasonic waves) and a receiver (detecting reflected waves), replacing what would traditionally require separate light source and sensor components. This multi-functionality reduces component count and enables device downsizing
2Area of stationary object
If typical sensing devices are designed for large area sensing, then coverage is improved, but device downsizing becomes difficult
Solution Approach 1:
The sensing device is divided into multiple pixel regions, each with its own piezoelectric transducer array. This segmentation allows the large sensing area to be covered by distributing multiple small, compact transducer units across the surface, maintaining large area coverage while keeping individual device components small and manageable
3Measurement precision
If typical sensing devices operate continuously, then sensing accuracy is maintained, but power consumption increases
Solution Approach 1:
The piezoelectric transducers operate in periodic pulses, emitting ultrasonic waves at specific intervals rather than continuously. This periodic operation maintains sensing accuracy by regularly updating touch detection while significantly reducing power consumption compared to continuous operation modes
Solution Approach 2:
The piezoelectric transducer serves as both transmitter and receiver, using the same component for both ultrasonic wave generation and detection. This self-service capability eliminates the need for separate transmit and receive components, reducing overall system power consumption while maintaining sensing accuracy
4Productivity
If typical sensing devices use complex signal driving, then sensing operations are performed, but signal delay occurs
Solution Approach 1:
The patent replaces complex optical signal processing with direct mechanical ultrasonic wave detection. The piezoelectric transducers directly convert mechanical touch forces into electrical signals through the piezoelectric effect, eliminating multiple signal conversion stages and reducing signal delay while improving sensing operation speed
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
The solution provides a sensing device with enhanced accuracy and security, reduced power consumption, and the ability to handle large area sensing without signal delays, making it suitable for integration into display devices.
Implementation Method 1
a transducer including a first driving electrode, a piezoelectric material layer, and a second driving electrode
Implementation Method 2
detecting a sensing signal from one or more second pixels adjacent to the one or more first pixels
Data Source
AI summary
The present disclosure relates to a sensing device and a display device including the sensing device. The sensing device includes a transducer including first and second driving electrodes and a piezoelectric material layer; first and second transmission transistors for alternatively supplying first and second driving voltages to the first driving electrode; and first and second reception transistors electrically connected between a readout line and a power supply line to which a power supply voltage is supplied. During an interval in which at least one pixel is driven, the first and second driving voltages are DC voltages with a voltage level different from each other, and the first and second transmission transistors repeat turn-on and turn-off at a timing different from each other. Through this, it is possible to reduce unnecessary power consumption, and therefore, a large area fingerprint sensor can be more efficiently implemented.