Sensor-Equipped Display Device Parasitic Capacitance Reduction
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Solution Overview
Problem
Existing sensor-equipped display devices face challenges in accurately detecting objects, particularly concavo-convex patterns like fingerprints, due to parasitic capacitance and sensitivity issues, which affect the precision and reliability of sensing operations.
Innovation Solution
The integration of a sensor-equipped liquid crystal display device with a current mirror circuit, operational amplifier, and capacitor configuration, where pixel electrodes function as detection electrodes, and a common electrode shields the detection area to reduce parasitic capacitance, enabling precise charge accumulation and discharge for enhanced sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel electrodes are used as detection electrodes with common electrode shielding, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The pixel electrodes serve dual functions as both display pixel electrodes and detection electrodes for sensing objects. The common electrode also serves dual purposes as both a display component and a shielding electrode to reduce parasitic capacitance. This multi-functionality approach improves measurement precision without requiring completely separate sensor structures.
Solution Approach 2:
The sensing function is merged with the existing display structure by using the pixel electrodes and common electrode from the display device itself as the sensing elements. The current mirror circuit and operational amplifier are integrated into the display device architecture, combining display and sensing functions into a unified system.
2Measurement precision
If additional structural elements are added to enhance sensing accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Existing display components (pixel electrodes, common electrode) are repurposed for sensing functions. The pixel electrodes detect objects while the common electrode provides shielding, eliminating the need for separate sensor structures and maintaining measurement precision without adding structural complexity.
Solution Approach 2:
The display device's own structures serve the sensing function. The pixel electrodes and common electrode inherently provide both display and sensing capabilities, and the device's internal circuits (current mirror, operational amplifier) handle the sensing processing, making the system self-sufficient without external sensor additions.
3Measurement precision
If parasitic capacitance is reduced through shielding, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The common electrode performs dual roles: maintaining display functionality and providing electrostatic shielding to reduce parasitic capacitance during sensing operations. This eliminates the need for separate shielding structures while improving detection precision.
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 configuration enhances the accuracy of object detection, including concavo-convex patterns, by minimizing parasitic capacitance and improving sensitivity, allowing for detailed sensing without additional structural elements, thus improving the overall performance of the sensor-equipped display device.
Implementation Method 1
parasitic capacitance and sensitivity issues, which affect the precision and reliability of sensing operations
Implementation Method 2
an integrator including an operational amplifier and a capacitor
Data Source
AI summary
According to one embodiment, a sensor-equipped display device includes a scanning line, a signal line, a pixel switch, a pixel electrode, a first common electrode, a detection electrode, a current mirror circuit, and an integrator. The integrator includes an operational amplifier including an inverting input terminal and a noninverting input terminal.