Touch Detection Using Differential Imaging on Self-Luminous Displays
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Solution Overview
Problem
Optical touch panels face reduced detection accuracy and increased power consumption when detecting touch locations without external light, as they rely solely on external light or require additional illumination sources.
Innovation Solution
The method involves capturing imaging data during both black and white display states on a touch panel, using transistors to control self-light-emitting elements, and detecting the location of the touch by identifying the sensor pixel with the greatest difference in imaging data between these states, thereby reducing the effect of external light and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If only external light is used for touch detection in an image-capture period, then power consumption is reduced, but detection accuracy deteriorates when there is no external light
Solution Approach 1:
The patent implements periodic action by alternating between self-light-emitting state and non-light-emitting state during the image-capture period. The light-emitting element is turned on during part of the image-capture period to provide illumination for touch detection, then turned off. This periodic illumination allows the system to maintain detection accuracy without requiring continuous external light sources, thereby resolving the contradiction between detection accuracy and power consumption.
2Measurement precision
If a separate illumination light source is provided to enable touch detection without external light, then detection accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent applies universality by making the light-emitting element serve dual functions: it acts as both the display element and the illumination source for touch detection. During the image-capture period, the light-emitting element is controlled to emit light specifically for illumination purposes, eliminating the need for a separate illumination light source. This multi-functionality reduces device complexity while maintaining detection accuracy.
Solution Approach 2:
The light-emitting element performs self-service by providing its own light for illumination during the image-capture period without requiring external illumination sources. The system uses the light-emitting element's capability to illuminate the touch detection area, thereby eliminating the need for additional separate illumination components and reducing overall device complexity.
3Use of energy by moving object
If the light-emitting element is turned off during the entire image-capture period, then power consumption is reduced, but the ability to detect touch without external light is lost
Solution Approach 1:
The patent implements periodic action by alternating between self-light-emitting state and non-light-emitting state during the image-capture period. The light-emitting element is turned on during part of the image-capture period to provide illumination for touch detection, then turned off. This periodic illumination allows the system to maintain detection accuracy without requiring continuous external light sources, thereby resolving the contradiction between detection accuracy and power consumption.
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 touch detection accuracy and reduces power consumption by utilizing both self-light-emitting and external light, eliminating the need for additional illumination sources and improving the reliability of touch location detection.
Implementation Method 1
a light-receiving element, and an image-capture pixel control signal line. In addition, a gate terminal of the third transistor and the image-capture pixel control signal line are electrically connected to each other
Data Source
AI summary
To reduce the effect of external light and to improve the accuracy of detecting the location of a touch. In an image-capture period, light emission from a self-light-emitting element is controlled, and imaging data at the time of displaying white on a display screen and imaging data at the time of displaying black on the display screen are output from each sensor pixel. The location of a sensor pixel where a difference between the two pieces of imaging data output from the same sensor pixel is the greatest is detected. Thus, the location of a touch of the object on the display screen is detected with high accuracy. By utilizing a difference between imaging data at the time of reverse display, the effect of external light can be reduced.