Touch Display Device with Non-Simultaneous LED and Photo Sensor Activation
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Solution Overview
Problem
Designing a touch control structure for ultra-large LED displays is challenging due to interference between Light-Emitting Diode (LED) light emission and photo sensor detection, which affects the accuracy of touch detection in large screen applications.
Innovation Solution
The touch display device includes LED units with photo sensors, where the LED and photo sensor are enabled non-simultaneously during a conductive period of a switch, minimizing light interference and improving detection accuracy by disabling surrounding LEDs during photo sensor activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If LED and photo sensor are enabled simultaneously, then the display function is achieved, but light emission interferes with photo sensor detection reducing touch detection accuracy
Solution Approach 1:
The patent implements periodic time-division multiplexing where LEDs and photo sensors are activated in alternating time slots. During photo sensor detection periods, LEDs are turned off to eliminate light interference, while during display periods, LEDs are activated and photo sensors are disabled. This periodic switching resolves the contradiction by ensuring that light emission and detection never occur simultaneously, thereby maintaining both display functionality and touch detection accuracy.
Solution Approach 2:
The patent applies preliminary action by disabling LEDs before activating photo sensors for touch detection. The control system anticipates the need for accurate touch detection and proactively turns off LED emission in advance, preventing light interference before it can affect the photo sensors. This preliminary disabling ensures that when photo sensors become active, the environment is already free from harmful light emission.
2Illumination intensity
If LED is always on for display, then display quality is maintained, but photo sensor detection is interfered with
Solution Approach 1:
The system employs periodic action by switching between display mode and detection mode. In display mode, LEDs are illuminated at full intensity to maintain display quality while photo sensors remain inactive. In detection mode, LEDs are turned off and photo sensors are activated for touch detection. This periodic alternation ensures that high illumination intensity and accurate touch detection are achieved at different times without mutual interference.
Solution Approach 2:
The patent applies dynamics by making the LED illumination state changeable rather than static. The LED brightness is dynamically adjusted based on the operational mode: fully on during display periods and completely off during detection periods. This dynamic control allows the system to optimize both display quality and touch detection accuracy by adapting the illumination state to the current functional requirement.
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 the accuracy of touch detection by ensuring that the photo sensor is not interfered with by light emission, thereby improving the overall performance of the touch display device.
Implementation Method 1
Each LED unit includes a LED and a photo sensor
Data Source
AI summary
A touch detection method includes the following steps: (1). providing a touch display device, wherein the touch display device includes a plurality of LED units and a plurality of switches, each LED unit includes a LED and a photo sensor, and the switches are electrically coupled to the LED units; and (2). enabling the LED and a photo sensor coupled to the conductive one non-simultaneously during a conductive period of a conductive one of the switches. As a result, an influence of a touch detection of the photo sensor by a light emission of the LED could be reduced.