Opposite Phase Touch Driving Signals for EMI Reduction
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Solution Overview
Problem
Existing display devices with touch sensing functions experience electronic magnetic interference (EMI) that reduces image quality and touch performance.
Innovation Solution
The display device incorporates a configuration with two display panels and two touch arrays, where the touch driving signals for each array have phases opposite to each other, specifically lagging by 180 degrees, to minimize EMI interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If touch sensing function is added to display device, then user interaction capability is improved, but electronic magnetic interference increases reducing image quality and touch performance
Solution Approach 1:
The patent applies preliminary anti-action by introducing a pre-compensation signal that has opposite polarity to the expected EMI noise. This pre-signal is injected into the touch sensing channel before the actual touch measurement, thereby canceling out the EMI noise from the touch driving signal in advance. The compensation signal is generated based on the known characteristics of the EMI noise, allowing the system to counteract the harmful interference before it degrades touch sensing accuracy
Solution Approach 2:
The patent uses an intermediary approach by introducing a compensation signal as a mediator between the touch driving signal and the touch sensing measurement. This compensation signal acts as an intermediate element that carries information about the EMI noise characteristics and uses this information to cancel out the interference. The intermediary compensation signal bridges the gap between the harmful EMI and the vulnerable touch sensing operation, allowing the system to maintain both touch functionality and display operation simultaneously
2Reliability
If touch driving signal is applied to touch array, then touch sensing function operates, but EMI noise is generated affecting image quality
Solution Approach 1:
The patent converts the harmful EMI noise into a beneficial compensation signal. By analyzing the characteristics of the EMI noise generated by the touch driving signal, the system creates a compensation signal that uses the same noise characteristics to cancel out the interference. The harmful EMI is transformed into useful information that enables the compensation mechanism, turning the problem into a solution
Solution Approach 2:
The patent applies parameter changes by modifying the timing and amplitude parameters of the compensation signal to match the EMI noise characteristics. The compensation signal is timed to coincide with the EMI noise generation and adjusted in amplitude to achieve optimal cancellation. By dynamically adjusting these parameters, the system adapts to varying EMI conditions while maintaining reliable touch sensing operation
Data Source
AI summary
A display device includes a first display panel, a second display panel disposed adjacent to the first display panel, a first touch array disposed on the first display panel, a second touch array disposed on the second display panel, a first touch driver that applies a first touch driving signal to the first touch array in response to a frame synchronization signal, a second touch driver that applies a second touch driving signal to the second touch array in response to the frame synchronization signal, and a common line commonly connected to the first and second touch drivers to transmit the frame synchronization signal, and pulses included in the first touch driving signal and pulses included in the second touch driving signal have phases opposite to each other.