Touch-Sensitive LED Display With Integrated Optical Sensing for Thin Screens
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Solution Overview
Problem
Existing touch-sensitive devices require multiple layers for both display and touch sensing functionalities, leading to thicker screens and increased complexity, cost, and reduced durability.
Innovation Solution
Integrate LED arrays that provide both display and touch sensing capabilities by alternating between illumination and sensing modes, using a subset of LEDs for touch detection, minimizing additional layers and optimizing spatial and temporal distribution for high accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple layers of flat materials are used to enable both touch screen and display functionalities, then both touch sensing and display functions can be achieved, but the screen assembly becomes thicker and device complexity increases
Solution Approach 1:
The patent combines the display function and touch sensing function into a single integrated LED array structure. The same LED elements that emit light for display also detect touch by measuring changes in incident light, eliminating the need for separate capacitive touch sensor layers and reducing overall assembly thickness.
Solution Approach 2:
The LED elements serve dual purposes: they function as light-emitting diodes for display output and as optical sensors for touch detection. By operating in different modes (emission mode and sensing mode), the same physical components perform multiple functions, reducing the number of required layers.
2Measurement precision
If multiple capacitive touch sensor layers are used to detect positions along perpendicular axes, then high-accuracy touch sensing is achieved, but the number of components and manufacturing complexity increase
Solution Approach 1:
The patent segments the LED array into different operational groups that can be selectively activated for sensing. By dividing the display into regions and controlling which LED elements operate in sensing mode versus display mode, the system achieves accurate touch detection without requiring multiple sensor layers.
Solution Approach 2:
Instead of stacking multiple sensor layers in the vertical dimension to achieve multi-axis touch detection, the patent uses temporal multiplexing and spatial distribution of sensing LEDs to achieve the same detection capability. The sensing function is distributed across time and space rather than concentrated in multiple physical layers.
3Device complexity
If LED elements alternate between emitting light and detecting incident light for touch sensing, then the same components perform both display and sensing functions, but visual disruption and display quality degradation may occur
Solution Approach 1:
The patent implements periodic switching between display mode and sensing mode for the LED elements. By using time-division multiplexing with appropriate duty cycles, the system alternates between illumination and sensing functions, allowing both operations to occur without requiring separate physical components 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
Enables thinner devices with reduced complexity and cost, while maintaining high display quality and sensitivity, allowing for adaptive touch detection and localization with minimal visual disruption.
Implementation Method 1
LEDs can emit light in display screens and can also be used to detect light when bias of the LEDs is reversed
Implementation Method 2
LEDs can also be used to detect light when bias of the LEDs is reversed
Data Source
AI summary
Methods, devices, and media for sensing a touch on a display panel including an array of pixels. A method includes controlling first pixels to operate in an illumination state; controlling second pixels to repeatedly switch between operating in the illumination state and operating in a sensing state; generating sensing signals indicative of levels of light detected by the second pixels; detecting a touch input to the display panel based on the generated sensing signals; and in response to detecting the touch input to the display panel, changing at least one of (i) a frequency at which the second pixels switch between operating in the illumination state and in the sensing state, (ii) a duty cycle for operating the second pixels in the sensing state, or (iii) which of the pixels in the array of pixels are controlled to switch between operating in the illumination state and in the sensing state.