Display Driver Frequency Switching to Prevent Touch Signal EMI
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Solution Overview
Problem
Touch signals in display devices act as electronic interference (EMI) for internal components, reducing the reliability of operations in touch sensors and display devices.
Innovation Solution
A display driver that changes the frequency of internal signals to prevent interference with touch signals by using a frequency counter, comparator, and frequency generator to generate a feedback signal indicating a different frequency when touch and interface signals match.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the display driver uses a fixed frequency for interface signals, then the circuit design is simple, but interference occurs when the interface signal frequency matches the touch signal frequency
Solution Approach 1:
The frequency counter and comparator detect frequency matching between interface signals and touch signals in advance, before interference can occur. This preliminary detection allows the system to proactively adjust frequencies to prevent EMI rather than reacting to interference after it occurs.
Solution Approach 2:
The system dynamically changes the frequency parameter of interface signals based on detection results. When a frequency match is detected, the frequency generator modifies the interface signal frequency to a different value, thereby eliminating the EMI condition while maintaining signal functionality.
2Reliability
If signal wires for interface and touch signals are separated to avoid interference, then interference is prevented, but dead space increases in the display device
Solution Approach 1:
Instead of changing the physical layout of signal wires, the system changes the frequency parameter of the signals themselves. By dynamically adjusting interface signal frequencies to avoid matching touch signal frequencies, the patent eliminates interference while allowing wires to overlap, thereby reducing dead space.
Solution Approach 2:
The patent transitions from solving the interference problem in the spatial dimension (separating wires) to solving it in the frequency dimension (adjusting signal frequencies). This dimensional shift allows wires to occupy the same physical space without causing interference, as long as their frequencies are different.
3Reliability
If the display driver actively monitors and adjusts signal frequencies, then interference is prevented, but the control system becomes more complex
Solution Approach 1:
The frequency counter continuously monitors the frequencies of interface and touch signals, and the comparator feeds back comparison results to the frequency generator. This feedback loop enables automatic frequency adjustment when matching is detected, maintaining reliability through continuous monitoring and correction.
Solution Approach 2:
The display driver performs self-diagnosis and self-adjustment regarding frequency conflicts. The integrated frequency counter, comparator, and frequency generator within the display driver enable it to autonomously detect and resolve frequency matching issues without external intervention, reducing the need for additional control system complexity.
Data Source
AI summary
A driving circuit includes a sensor driver and a display driver. The sensor driver outputs a touch signal, and the display driver receives a first interface signal from a processor and outputs a feedback signal to the processor. The feedback signal is output when a first frequency of the first interface signal and a second frequency of the touch signal received from the sensor driver match. The third frequency is different from the first frequency.