Touch Drive Signal Frequency Adjustment for Noise Reduction
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Solution Overview
Problem
Capacitive-type touch detection devices in display devices are prone to noise interference from both external and internal sources, which can degrade touch detection sensitivity and stability, especially when the sampling frequency of the detection result is close to the frequency of external noise.
Innovation Solution
A display device with a touch detection function that includes a touch detection element, a scan drive unit, and a noise detector, where the touch drive signal frequency is changed in the touch detection operation period when noise is detected, allowing the touch detection unit to sample the detection result synchronized with the touch drive signal and reducing noise interference by differing the sampling frequency from external noise frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the touch detection device uses a fixed sampling frequency close to external noise frequency, then the touch detection can be performed efficiently, but the noise interference degrades detection sensitivity and stability
Solution Approach 1:
The patent applies dynamics by making the sampling frequency variable rather than fixed. The control unit dynamically adjusts the sampling frequency of the touch drive signal based on detected noise characteristics. When noise is detected at a particular frequency, the system changes the sampling frequency to avoid overlap, thereby maintaining detection sensitivity while preserving efficient touch detection operation.
Solution Approach 2:
The patent implements parameter changes by modifying the sampling frequency parameter of the touch drive signal. The control unit detects noise frequency components and adjusts the sampling frequency parameter to differ from the noise frequency, preventing noise from being sampled along with the touch detection signal. This parameter adjustment resolves the contradiction by eliminating noise interference while maintaining operational efficiency.
2Measurement precision
If the sampling frequency is changed to avoid noise frequencies, then the touch detection sensitivity is improved, but the complexity of the drive system increases
Solution Approach 1:
The patent employs feedback by using the noise detector to continuously monitor the electromagnetic environment and provide information about noise frequencies to the control unit. The control unit then adjusts the sampling frequency based on this feedback, creating a closed-loop system that automatically optimizes touch detection sensitivity without requiring complex manual configuration or multiple hardware components.
Solution Approach 2:
The system implements self-service by having the display device autonomously detect and respond to noise interference. The noise detector and control unit work together to automatically adjust the sampling frequency without external intervention, allowing the system to self-correct and maintain optimal performance in varying electromagnetic environments without increasing overall system complexity.
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 stability and sensitivity of touch detection by effectively reducing the influence of noise, ensuring accurate detection of external proximity objects even when noise frequencies overlap with the sampling frequency.
Implementation Method 1
A capacitance is formed between the common electrode and the touch detection electrode, and the formed capacitance changes according to an external proximity object.
Data Source
AI summary
According to an aspect, a display device with a touch detection function includes: a scan drive unit that supplies a touch drive signal to a touch detection element in a touch detection operation period different from a display operation period in which a pixel signal and a display drive signal are sequentially supplied to display elements to perform display scanning; and a noise detector that detects noise included in a frequency component sampled by a touch detection unit. When the noise detector detects the noise, the scan drive unit changes a frequency of the touch drive signal in the touch detection operation period and supplies the changed frequency to the touch detection element.