Display Device Touch Detection Noise Reduction
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Solution Overview
Problem
The existing display devices with combined display and touch sensor units face challenges in maintaining detection sensitivity and smooth input due to noise interference when the touch sensor unit operates during image rewriting by the display unit, particularly at high frequencies required for smooth handwriting input.
Innovation Solution
A method for driving a display device that includes alternating periods for image rewriting by the display unit and touch detection by the touch sensor unit, utilizing a gate driver to supply signals to only some pixels during touch detection periods, and employing transistors with metal oxides in the channel formation region to reduce off-state current and noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the touch sensor unit performs detection operation at the same timing when the display unit rewrites an image, then the detection sensitivity of the touch sensor unit deteriorates due to noise influence, but separating the timing reduces detection frequency and affects smooth input
Solution Approach 1:
The frame period is segmented into a first period for touch detection and a second period for image rewriting. This temporal segmentation allows the touch sensor unit and display unit to operate at different times, eliminating noise interference during touch detection while maintaining sufficient detection frequency for smooth input operation
Solution Approach 2:
The display device alternates between a first period where the touch sensor unit detects touch and a second period where the display unit rewrites images. This periodic action pattern ensures that touch detection always occurs during noise-free intervals while maintaining the required detection frequency of 80-100 times per second
2Productivity
If the frame frequency is increased to 60 Hz or higher for smooth input, then the detection operation frequency must be 80 times or more per second, but this increases power consumption and noise interference
Solution Approach 1:
By implementing periodic touch detection at specific frame rates (80-100 Hz) during noise-free first periods, the system achieves smooth input operation without requiring continuous high-frequency operation of both display and touch units simultaneously, thereby reducing overall power consumption
Solution Approach 2:
The touch detection operation is performed in advance during the first period before the display unit starts image rewriting in the second period. This preliminary action ensures that touch input is captured before noise generation begins, maintaining high detection frequency without increasing power consumption during noise-prone periods
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 detection sensitivity and smooth input for the touch sensor unit while reducing power consumption by minimizing noise interference and extending the periods available for touch detection, thereby improving overall performance and efficiency.
Implementation Method 1
employing transistors with metal oxides in the channel formation region to reduce off-state current and noise interference
Data Source
AI summary
A display device that achieves both high detection sensitivity of the touch sensor unit and smooth input on the touch sensor unit is provided. A method for driving a display device includes a first period and a second period. The display device includes pixels, a gate driver, and a touch sensor unit. The touch sensor unit detects a touch in the first period and stops detecting a touch in the second period. The gate driver supplies signals to some of the pixels and does not supply signals to the other pixels in the second period.