In-Cell Display Touch Drive Signal Frequency Adjustment
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Solution Overview
Problem
In-cell display devices face challenges with false touch detection due to exogenous noise at frequencies similar to the touch drive signal, and the reduction of touch drive signal frequency decreases touch detection sensitivity.
Innovation Solution
A display system with a control circuit that alternately arranges display and touch detection periods within a frame period, detects noise at the touch drive signal frequency, and adjusts the frequency to a lower value and detection time when noise is detected, while maintaining equivalent touch detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frequency of the touch drive signal is reduced to suppress false detection from exogenous noise, then false detection is reduced, but touch detection sensitivity decreases
Solution Approach 1:
The patent implements dynamic frequency adjustment of the touch drive signal based on detected noise conditions. The control circuit monitors for exogenous noise and adaptively changes the touch drive signal frequency between a first frequency (when noise is present) and a second frequency (when noise is absent), allowing the system to optimize both false detection suppression and touch detection sensitivity under varying environmental conditions
Solution Approach 2:
The patent changes the frequency parameter of the touch drive signal dynamically based on noise detection results. By switching between different frequency values (first frequency for noise suppression, second frequency for sensitivity), the system resolves the contradiction between reliability and measurement precision through parameter adaptation
2Measurement precision
If the detection time is extended to improve touch detection accuracy, then detection accuracy improves, but response time increases
Solution Approach 1:
The patent implements dynamic adjustment of the detection time period based on noise conditions. The control circuit extends the detection time period when exogenous noise is detected to improve detection accuracy, and reduces it when noise is absent to maintain fast response, thereby resolving the contradiction between accuracy and response time through adaptive timing
3Reliability
If the touch drive signal frequency is changed dynamically to suppress noise, then false detection is reduced, but system complexity increases
Solution Approach 1:
The patent employs a feedback mechanism where the control circuit continuously monitors for exogenous noise and adjusts the touch drive signal frequency accordingly. The noise detection output feeds back to the frequency control, creating a closed-loop system that automatically suppresses false detection while managing complexity through intelligent control algorithms
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 solution effectively suppresses false detection caused by exogenous noise and maintains touch detection sensitivity by dynamically adjusting the touch drive signal frequency and detection time.
Implementation Method 1
The touch detection circuit detects a noise at a frequency of the touch drive signal based on the touch detection signal
Implementation Method 2
a drive circuit that supplies a touch drive signal to each of the plurality of common electrodes
Implementation Method 3
a liquid crystal layer; a pixel electrode; a common electrode... the liquid crystal layer, the pixel electrode, and the common electrode
Data Source
AI summary
A display device includes a plurality of common electrodes. A second drive circuit supplies a touch drive signal to each of the plurality of common electrodes. A touch detection circuit performs detection of a touch by an object to the display device, based on a touch detection signal received from each of the plurality of common electrodes in one or more touch detection periods. A length of the one or more touch detection periods is a detection time. The touch detection circuit detects a noise at a frequency of the touch drive signal based on the touch detection signal. When the noise is detected, the control circuit changes the frequency of the touch drive signal to be lower than the frequency used when the noise is not detected and changes the detection time to be longer than the detection time used when the noise is not detected.