Infrared Touch Sensing Surface with Quantum Dot Detectors
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Solution Overview
Problem
Existing touch sensing technologies in displays, such as OLED panels, face issues with pre-touch detection, poor accuracy in distance estimation, and inability to reliably determine the positions of multiple fingers, leading to suboptimal user interaction.
Innovation Solution
An in-cell optical detection system utilizing embedded quantum dot photo-detectors and spatial-temporal control of infrared light emission to differentiate between touch and proximity, with two sets of sensors and emitters operating at different wavelengths to accurately detect finger positions and prevent pre-touch errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensing or optical sensing is used for touch detection, then touch sensitivity is improved, but pre-touch detection occurs causing false positives
Solution Approach 1:
The patent segments the sensing function into two distinct systems: a first optical sensing system for proximity detection and a second capacitive sensing system for touch detection. This segmentation allows each system to operate independently with optimized parameters, preventing false positives while maintaining accurate touch detection.
Solution Approach 2:
The patent introduces an intermediary processing layer that receives signals from both sensing systems and uses temporal correlation to determine valid touches. The intermediary filters out false positives by requiring consistent signals across both systems within a specific time window.
2Adaptability or versatility
If optical sensing is used for proximity detection, then hover detection capability is improved, but distance estimation accuracy deteriorates
Solution Approach 1:
The patent changes the detection parameter from continuous optical intensity (which provides proximity detection) to temporal correlation analysis of optical and capacitive signals. This parameter transformation enables both proximity detection and accurate distance estimation by analyzing the timing relationship between hover and touch events.
3Measurement precision
If multiple optical sensors are used for multi-finger detection, then resolving power is improved, but device complexity increases
Solution Approach 1:
The patent merges the optical sensing and capacitive sensing systems into a unified detection architecture where both sensor types work together. This combination allows the system to achieve superior multi-finger resolution through complementary strengths while sharing processing resources, thereby reducing overall system complexity.
Solution Approach 2:
The patent creates a universal sensing architecture where the same processing system handles both proximity detection, touch detection, and multi-finger position resolution. This multi-functionality reduces device complexity by consolidating processing tasks rather than requiring separate dedicated systems for each function.
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 system effectively disambiguates touch from proximity, offers superior resolving power and distance estimation, and enables interaction with various input tools like light pens and gloved fingers, while reducing power consumption by disabling hover sensing when needed.
Implementation Method 1
a first emitter of light, configured to emit light at a first infrared wavelength into a region between the two principal surfaces
Implementation Method 2
The IR light for this function is constrained to a waveguide material in the display's front surface. When a finger makes contact with this waveguide material, it frustrates total internal reflection and scatters light downwards to the photodetector elements.
Implementation Method 3
A first one of these sets of sensors is activated when a finger makes contact with the display surface. The IR light for this function is constrained to a waveguide material in the display's front surface.
Implementation Method 4
embedded quantum dot photo-detectors, which have the capability of responding differentially to different narrow-band light emission
Implementation Method 5
a plurality of second emitters of light, configured to emit light at a second infrared wavelength differing from the first infrared wavelength and to illuminate a volume exterior to the display
Implementation Method 6
The second set of sensors, e.g., quantum dot detectors, can be coordinated with the second emitter to detect light reflections from objects in the vicinity of the display.
Data Source
AI summary
A system and method for hover detection and touch detection in a display. In one embodiment, a first set of infrared (IR) emitters illuminates the interior of a transparent layer and the IR light is confined to the interior of the layer by total internal reflection, unless an object, such as a finger, touches the surface of the layer. Additional IR emitters at a different wavelength illuminate the volume outside of the display for hover detection. Two sets of wavelength-selective IR sensors, such as quantum dot sensors, are embedded in the display and are used to localize one or more fingers touching, or hovering near, the display.