Optical Edge Sensors for Full Display Touch Coverage
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Solution Overview
Problem
Existing electronic devices with displays face challenges in integrating capacitive touch sensors along the borders, as traditional non-optical touch sensors struggle to cover the entire display area, including the border regions.
Innovation Solution
The implementation of an optical sensor in the border region of the display, utilizing infrared light-emitting and sensing pixels, which work in conjunction with a non-optical touch sensor in the active area to provide comprehensive touch input coverage across the entire display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a non-optical touch sensor is used in the active area, then touch input can be gathered in the active area, but the border region cannot be covered for touch input
Solution Approach 1:
The display is divided into two regions with different sensor types: the active area uses non-optical touch sensors while the border region uses optical sensors. This segmentation allows each region to be optimized for its specific sensing requirements, enabling complete border coverage that would not be possible with a single sensor type
Solution Approach 2:
Optical sensors are introduced as intermediary elements in the border region to bridge the gap left by non-optical sensors. These optical sensors detect light changes caused by touch, providing sensing capability in regions where traditional capacitive sensors cannot effectively operate
2Area of stationary object
If optical sensors are added to the border region, then complete display area coverage is achieved, but device complexity increases
Solution Approach 1:
The display structure is designed to serve multiple functions: the display itself provides visual output while also serving as the sensing medium for optical touch detection in the border region. This multi-functionality reduces the need for separate dedicated sensing components, thereby limiting the increase in device complexity despite achieving complete area coverage
3Adaptability or versatility
If light-emitting and light-sensing pixels are placed in the border region, then optical touch sensing is enabled, but manufacturing complexity increases
Solution Approach 1:
Different pixel types are placed in different regions: standard light-emitting pixels in the active area and specialized light-sensing pixels in the border region. This local differentiation allows manufacturing processes to be optimized for each region's specific requirements, making the overall manufacturing process more manageable despite the diversity of components
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 solution enables most or all of the display area to be responsive to user touch input, even in regions where traditional capacitive touch sensing is challenging, by effectively utilizing both optical and non-optical touch sensing technologies.
Implementation Method 1
an optical sensor in the border region may be formed from infrared light-emitting pixels and infrared light-sensing pixels
Implementation Method 2
an optical sensor in the border region may be formed from infrared light-emitting pixels and infrared light-sensing pixels
Data Source
AI summary
A display may have an array of light-emitting pixels that display an image in an active area of the display. These light-emitting pixels may be visible light pixels such as red, green, and blue thin-film organic light-emitting diode pixels. The display may also have a border region that runs along a peripheral edge of the active area. The border region may be free of pixels that display image light, whereas the active area may be free of light detectors. A non-optical touch sensor such as a capacitive touch sensor may overlap the active area to gather touch input from the active area. The non-optical touch sensor may not overlap any portion of the border region. In the border region, an optical sensor formed from infrared light-emitting pixels and infrared light-sensing pixels or other optical sensing circuitry may serve as an optical touch sensor.