Integrated Touch and Pressure Sensing in Display Devices
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Solution Overview
Problem
Existing display devices require separate touch sensors for position detection and pressure detection, leading to issues with thickness, cost, and optical characteristics due to the need for non-transparent pressure-sensitive sensors and additional components.
Innovation Solution
A display device with a built-in touch sensor system that uses a light emitting element layer, inorganic insulating layers, and shared electrodes with an insulating elastic layer to detect touch position and pressing by measuring changes in capacitance, eliminating the need for separate sensors and components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate pressure-sensitive sensors are mounted on the back side or in peripheral regions of the display, then pressing detection function is achieved, but device thickness increases and optical characteristics deteriorate
Solution Approach 1:
The patent combines the touch position detection function and pressing detection function into a single sensor structure. The same electrode pattern and insulating elastic layer are used for both mutual capacitance measurement (touch position) and self-capacitance measurement (pressing force), eliminating the need for separate pressure-sensitive sensors on the back side or in peripheral regions.
Solution Approach 2:
The sensor structure is designed to perform multiple functions: the first and second electrodes with the insulating elastic layer simultaneously enable touch position detection through mutual capacitance measurement and pressing force detection through self-capacitance measurement, making the sensor universal for both detection purposes.
2Reliability
If separate touch sensors and pressure sensors are arranged and bonded together, then both touch position detection and pressing detection are achieved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent merges the touch sensor and pressure sensor into a single integrated structure. The same electrode pattern, insulating elastic layer, and control circuit are used for both touch position detection and pressing force detection, eliminating the need for separate sensors and their bonding processes.
Solution Approach 2:
The sensor structure is designed to perform multiple functions: the same hardware components (electrodes, insulating elastic layer) are used for both touch position detection through mutual capacitance measurement and pressing force detection through self-capacitance measurement, simplifying manufacturing.
3Reliability
If non-transparent pressure-sensitive sensors are used for pressing detection, then pressing detection function is achieved, but optical characteristics of the display deteriorate
Solution Approach 1:
The patent replaces the traditional mechanical or non-transparent pressure-sensitive sensor with a capacitive sensing system that uses transparent conductive electrodes and an insulating elastic layer. This allows pressing force detection through electrical capacitance measurement while maintaining optical transparency for display quality.
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 enhances thickness, cost, and optical characteristics while maintaining touch sensitivity, allowing for a thinner frame and integrated touch and pressure detection without additional peripheral sensors.
Implementation Method 1
compression of the insulating elastic layer based on a pressing force
Implementation Method 2
measure a first physical quantity corresponding to a first capacitance being a parasitic capacitance formed in each of electrode groups including the plurality of first electrodes and the plurality of second electrodes
Implementation Method 3
a first capacitance being a parasitic capacitance formed in each of electrode groups including the plurality of first electrodes and the plurality of second electrodes
Data Source
AI summary
A sensing circuit is configured to measure a first physical quantity corresponding to a first capacitance being a parasitic capacitance formed in at least one of electrode groups including a plurality of first electrodes and a plurality of second electrodes, to thereby detect that significant change has occurred in the first capacitance due to touching of a conductor when an obtained first measurement value is out of a first range. The sensing circuit is further configured to measure a second physical quantity corresponding to a second capacitance formed between each of the plurality of first electrodes and each of the plurality of second electrodes, to thereby detect that significant change has occurred in the second capacitance due to compression of an insulating elastic layer based on a pressing force when an obtained second measurement value is out of a second range.