Sensor Driver Phase Cancellation for Display EMI Reduction
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Solution Overview
Problem
Display devices face electromagnetic interference (EMI) issues due to the interaction between driving signals for sensors and image display signals, leading to reduced sensing sensitivity and display quality, with existing frequency band adjustments being inadequate.
Innovation Solution
A sensor device and display device design that utilizes a sensor panel divided into areas, employing reference signals with opposite phases to receive sensing signals, minimizing EMI without altering frequency bands, and applying shield signals with reverse phases to improve signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If driving signals are supplied to sensors of the sensor device, then sensing function is enabled, but electromagnetic interference occurs that deteriorates display quality
Solution Approach 1:
The sensor panel is divided into a first area and a second area, with sensors in each area driven by reference signals with opposite phases. This segmentation allows the EMI from different sensor groups to cancel each other out, reducing overall electromagnetic interference while maintaining sensing functionality across the entire panel.
Solution Approach 2:
Reference signals with opposite phases are applied to sensors in different areas, creating counterbalancing electromagnetic fields. The EMI generated by sensors in the first area is counterweighted by the opposite-phase signals from sensors in the second area, effectively reducing net electromagnetic interference with the display device.
2Object-affected harmful factors
If frequency band of driving signal is changed to avoid EMI, then electromagnetic interference is reduced, but finding additional appropriate frequency band becomes difficult
Solution Approach 1:
Instead of changing the frequency band, the invention changes the phase parameter of the driving signals. By applying reference signals with opposite phases to different sensor areas, the system reduces EMI through phase cancellation while maintaining the same frequency band, thus avoiding the constraint of finding additional frequency bands.
3Reliability
If signals for image display are supplied to display device, then image display function is enabled, but sensing sensitivity is reduced due to electromagnetic interference
Solution Approach 1:
By segmenting the sensor panel into areas driven by opposite-phase reference signals, the EMI affecting the display device is reduced. This allows the display function to operate with better image quality while the sensors maintain their sensitivity, as the counterbalancing signals reduce the net electromagnetic noise in the system.
Data Source
AI summary
A sensor device includes: a sensor panel including sensors arranged in a matrix form and sensor lines electrically connected to the sensors one-to-one; and a sensor driver configured to receive sensing signals from the sensors through the sensor lines, wherein the sensor driver is configured to simultaneously receive a first sensing signal from a first sensor using a first reference signal and a second sensing signal from a second sensor using a second reference signal, wherein the first reference signal and the second reference signal have a same waveform, a phase of the second reference signal is different from a phase of the first reference signal, and wherein a phase of the second sensing signal is different from a phase of the first sensing signal.