Touch Display Panel Audible Noise Suppression via Variable Period Switching
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Solution Overview
Problem
Touch display panels with integrated touch and display functions suffer from audible noise due to switching frequencies within the range of human hearing, caused by the periodic switching between display and touch phases, which affects user experience.
Innovation Solution
A driving apparatus and method for a touch display panel that alternately switches between a common reference voltage and a touch driving signal, with varying time lengths for display and touch periods, and different waveforms or active periods within touch frames, to alter the switching frequency and reduce audible noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the touch display panel alternately switches between display phase and touch phase with fixed time lengths, then the driving control is simple and stable, but audible noise occurs due to switching frequency within human hearing range
Solution Approach 1:
The patent applies dynamics by making the time lengths of display periods and touch periods variable rather than fixed. The driving apparatus dynamically adjusts the time lengths of display periods (DP1, DP2) and touch periods (TP1, TP2) in alternating touch display periods, causing the switching frequency to vary over time. This dynamic adjustment moves the switching frequency out of the human audible range, eliminating audible noise while maintaining driving control simplicity through automated adjustment.
2Object-generated harmful factors
If the switching frequency is increased to move out of audible range, then audible noise is reduced, but the time for each display and touch period decreases, affecting display quality and touch sensing accuracy
Solution Approach 1:
The patent applies parameter changes by systematically varying the time length parameters of display periods and touch periods. Instead of using a fixed high switching frequency that would compromise quality, the patent changes the duration parameters (DP1, DP2, TP1, TP2) to achieve variable switching frequencies. This allows each individual period to maintain sufficient length for high-quality display and accurate touch sensing, while the overall switching frequency varies to avoid audible ranges.
3Object-generated harmful factors
If the time lengths of display and touch periods are made variable, then audible noise is suppressed by varying switching frequency, but the driving control complexity increases
Solution Approach 1:
The patent applies periodic action by implementing a systematic alternating pattern of different time length configurations. The driving apparatus uses periodic sequences of display periods and touch periods with varying time lengths (DP1, DP2, TP1, TP2), creating a structured variation in switching frequency. This periodic approach suppresses audible noise through frequency modulation while maintaining manageable driving control complexity through automated periodic adjustment sequences.
Data Source
AI summary
The driving apparatus for driving a touch display panel includes a first voltage generating circuit configured to generate a common reference voltage, a second voltage generating circuit configured to generate a touch driving signal, and a control circuit configured to generate a switching signal. The switching signal is at the first voltage level during display periods for providing the common reference voltage to the touch display panel. The switching signal is at the second voltage level during touch periods for providing the touch driving signal to the touch display panel. A first touch display period includes a first display period a first touch period adjacent to the first display period. A second touch display period includes a second display period and a second touch period adjacent to the second display period. The first touch display period and the second touch display period are different in time length.