Shared Transparent Electrode for Reflective Display Touch Sensor
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Solution Overview
Problem
Existing electrophoretic displays with projected capacitive touch sensors face challenges in optical performance due to the presence of light-absorbing conductive materials and interfaces, which degrade image quality, especially in reflective displays.
Innovation Solution
The solution involves combining the function of one electrode layer of a projected capacitive touch sensor array with that of a transparent driving electrode of an electrophoretic display, using a shared transparent electrode to improve optical performance. This is achieved by embedding the touch sensor electrodes in a semi-conductive layer that promotes conductivity without significant optical absorption, allowing for dual functionality in addressing the display and sensing touch inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional conductive materials are used in touch sensor electrodes, then electrical conductivity is improved, but optical performance deteriorates due to light absorption
Solution Approach 1:
The patent combines the transparent electrode of the electrophoretic display with one electrode layer of the projected capacitive touch sensor into a single shared transparent electrode structure. This merging eliminates the need for separate conductive layers, reducing the number of light-absorbing interfaces while maintaining both display addressing and touch sensing functions.
Solution Approach 2:
The shared transparent electrode serves multiple functions simultaneously: it acts as the transparent driving electrode for addressing the electrophoretic display and as one of the capacitive sensing electrodes for detecting touch inputs. This multi-functionality resolves the contradiction by making a single component satisfy both electrical conductivity and optical transparency requirements.
2Adaptability or versatility
If multiple separate electrode layers are used for touch sensing and display addressing, then functional versatility is improved, but device complexity increases
Solution Approach 1:
The patent merges the display addressing electrode and touch sensor electrode into a single shared transparent electrode layer, reducing the total number of layers and interfaces in the device structure while maintaining both display and touch sensing capabilities through temporal multiplexing of functions.
Solution Approach 2:
The shared transparent electrode is designed to perform both display addressing and touch sensing functions by switching between modes: during display update periods it serves as the driving electrode, and during touch sensing periods it serves as the capacitive sensing electrode, thereby reducing device complexity without sacrificing functional versatility.
3Adaptability or versatility
If multiple interfaces between layers are present, then functional capability is improved, but optical performance deteriorates
Solution Approach 1:
By combining the transparent display electrode and touch sensor electrode into a single shared layer, the patent eliminates the interface between two separate conductive layers, thereby reducing the number of optical interfaces that cause light scattering and absorption, while maintaining both display and touch sensing functionalities.
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 approach enhances optical performance by reducing light absorption and improving image quality, while also enabling efficient touch sensing and display addressing through a shared electrode structure.
Implementation Method 1
embedding the touch sensor electrodes in a semi-conductive layer that promotes conductivity without significant optical absorption
Implementation Method 2
the first electrode layer, the dielectric layer, and the second electrode layer form a capacitive touch sensor that detects a touch input by sensing a change in capacitance at a touched point on the first electrode layer
Implementation Method 3
the second electrode layer, the semi-conductive layer, the electro-optic medium layer, and the third electrode layer form an electro-optic device in which the electro-optic medium layer is addressed by applying a driving voltage to the third electrode layer
Data Source
AI summary
A touch-enabled electro-optic display device has a stack of layers including, in order: a first electrode layer at a viewing surface of the touchscreen electro-optic display device; a dielectric layer; a second electrode layer; a semi-conductive layer; an electro-optic medium layer; and a third electrode layer. The second electrode layer, the semi-conductive layer, the electro-optic medium layer, and the third electrode layer form an electro-optic device in which the electro-optic medium layer is addressed by applying a driving voltage to the third electrode layer while holding the voltage on the second electrode layer constant. The first electrode layer, the dielectric layer, and the second electrode layer form a capacitive touch sensor that detects a touch input by sensing a change in capacitance at a touched point on the first electrode layer.