Sensor Device EMI Reduction via Periodic Signal Alternation
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Solution Overview
Problem
Display devices with integrated sensor devices face challenges due to electromagnetic interference (EMI) generated by driving signals, which can affect the display quality and operation of nearby electronic devices.
Innovation Solution
A sensor device is designed with first and second sensors arranged in different directions, and a sensor driver that transmits driving signals and offset signals based on orientation information. During specific periods, the sensor driver alternates the transmission of driving and offset signals to minimize EMI.
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 (EMI) is generated affecting other electronic devices
Solution Approach 1:
The sensor driver alternates between transmitting driving signals and offset signals in periodic time periods. During first time periods, driving signals are transmitted to sensor groups while offset signals are transmitted to other sensor groups. During second time periods, the roles are reversed. This periodic alternation reduces the duration that driving signals are active, thereby minimizing EMI generation while maintaining continuous sensing capability.
Solution Approach 2:
The sensor device divides sensors into multiple groups (first sensor groups and second sensor groups) and applies different signaling schemes to different groups at different times. This segmentation allows the system to transmit driving signals to only some sensor groups at any given moment, reducing the total EMI footprint while maintaining overall sensing functionality through the offset signaling to other groups.
2Reliability
If driving signals are supplied to sensors of the sensor device, then sensing operation is performed, but display quality is reduced due to noise
Solution Approach 1:
The sensor driver implements periodic alternation between driving signal transmission and offset signal transmission to different sensor groups. This reduces the overall noise footprint in the display device by ensuring that driving signals (which act as noise) are active for only portions of the time, while the offset signaling maintains sensing operation during the alternate periods.
3Reliability
If driving signals are generated by the sensor driver, then sensing function is activated, but electromagnetic interference affects operation of other electronic devices
Solution Approach 1:
The sensor driver generates driving signals and offset signals in alternating periodic periods. During first time periods, driving signals are generated for first sensor groups while offset signals are generated for second sensor groups. During second time periods, the generation is reversed. This periodic generation pattern reduces the cumulative EMI impact on other electronic devices while maintaining continuous sensing function.
Solution Approach 2:
The sensor driver segments the sensor array into multiple groups and generates different types of signals for different groups at different times. This segmentation strategy reduces the spatial and temporal footprint of EMI generation, as driving signals are generated for only some sensor groups at any given moment, while offset signal generation maintains sensing capability in other groups.
Data Source
AI summary
A sensor device includes first sensors, second sensors, and a sensor driver. The first sensors are arranged along a first direction, and the second sensors are arranged along a second direction. The sensor driver is configured to transmit driving signals to the first sensors through first sensor lines and to receive sensing signals from the second sensors through second sensor lines. During a first period, the sensor driver is configured to transmit the driving signals to a first group of sensors, and to transmit offset signals having a frequency that is equal to that of the driving signals and a phase that is different from that of the driving signals to a second group of sensors. During a second period, the sensor driver is configured to transmit the offset signals to the first group of sensors and to transmit the driving signals to the second group of sensors.