Optical Touch Detection via Alternating Display Frames
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Solution Overview
Problem
Conventional display devices with touch sensors struggle to accurately detect multiple contact points and contact strength on a display panel, as they either fail to register insulator contacts or require costly and image-quality-reducing pattern formation for touch detection.
Innovation Solution
A position detecting system that includes a display panel with alternating data voltages for image and pattern display, a position detecting sensor capturing images of patterns, and a backlight unit for illuminating the panel, allowing for the detection of contact positions and pressure through visible or infrared light, without permanently altering the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If patterns are permanently formed on the display panel for touch detection, then contact position detection accuracy is improved, but manufacturing cost increases and image quality deteriorates
Solution Approach 1:
The patent uses a camera to capture images of patterns displayed on the screen instead of permanently forming patterns on the panel. The patterns are temporarily displayed during dedicated detection frames, allowing touch position detection without permanent modifications to the display structure.
Solution Approach 2:
The system alternates between display frames and detection frames periodically. During detection frames, patterns are displayed and captured for touch detection, while during display frames, normal image content is shown. This periodic switching enables both functions without permanent pattern formation.
2Measurement precision
If patterns are permanently formed on the display panel for touch detection, then contact position detection is enabled, but the display panel size and thickness increase
Solution Approach 1:
Instead of embedding physical patterns in the panel structure, the patent displays patterns optically on the screen surface and captures them with a camera. This eliminates the need for additional physical layers or structures that would increase panel thickness.
Solution Approach 2:
The patent replaces the mechanical approach of embedding physical patterns and sensors into the panel with an optical system using display patterns and camera imaging. This substitution eliminates the need for additional physical space within the panel structure.
3Measurement precision
If conventional touch sensors are used, then single point contact detection works well, but multiple contact points cannot be distinguished
Solution Approach 1:
The camera captures an image containing all contact points simultaneously, creating a visual copy of the entire contact pattern. This allows the system to identify and distinguish multiple contact points based on their positions in the captured image, overcoming the limitation of conventional sensors that only detect single points.
4Adaptability or versatility
If capacitive touch sensor is used, then multiple contact points can be detected, but insulator contacts cannot be detected
Solution Approach 1:
The patent replaces the electrical field-based capacitive sensing mechanism with an optical imaging system. The camera captures light reflected from or emitted by the display patterns at contact points, allowing detection of any object that physically contacts the screen regardless of its electrical conductivity properties.
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 accurate detection of multiple contact points and contact strength without increasing the display panel's size or thickness, improving image quality by separating pattern frames from image frames and supporting both conductive and insulative contacts.
Implementation Method 1
capturing an image of the patterns when a position detecting mode of the position detecting sensor is turned on
Implementation Method 2
allowing for the detection of contact positions and pressure through visible or infrared light
Data Source
AI summary
The present disclosure relates to a position detecting system. The position detecting system includes a display panel including a plurality of pixels. The position detecting system also includes a data driving unit configured to apply a first data voltage and a second data voltage to the display panel, wherein the first data voltage is associated with display of an image on the display panel during a first frame and the second data voltage is associated with display of patterns on the display panel during a second frame. The position detecting system further includes a position detecting sensor configured to capture an image of the patterns when a position detecting mode of the position detecting sensor is turned on.