Common Electrode Interference Sensing for Display Accuracy
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Solution Overview
Problem
Current systems fail to effectively measure electromagnetic interference (EMI) in proximity sensor devices integrated with display devices due to image-dependent noise during display update times, leading to inaccurate positional information and increased system costs and size.
Innovation Solution
Operating a portion or all of the common electrodes for interference sensing during non-display update times, allowing for accurate interference measurements to improve positional information accuracy, and using a processing system with driver and receiver modules to manage capacitive sensing and display updating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If common electrodes are operated for capacitive sensing during display update times, then sensing rate increases, but measurement precision deteriorates due to image-dependent noise
Solution Approach 1:
The display frame time is segmented into multiple portions: a first portion for capacitive sensing operations and a second portion for interference sensing operations. This temporal segmentation allows the system to perform both sensing tasks without interference, as each operation type is isolated to its designated time window within the display frame cycle.
Solution Approach 2:
The system implements periodic interference sensing operations at specific intervals within display frame times. By establishing a periodic schedule where interference sensing occurs in the second portion of display frames while capacitive sensing occurs in the first portion, the system maintains regular measurement cycles without continuous interference contamination.
2Object-affected harmful factors
If EMI-generating components are distanced from proximity sensing components, then interference is reduced, but device complexity and size increase
Solution Approach 1:
The system converts the harmful EMI generated by display components into a measurable signal by implementing interference sensing operations during the second portion of display frames. Instead of trying to eliminate or distance EMI sources, the system acknowledges their presence and periodically measures the interference, then uses this measurement data to compensate for and remove EMI effects from the capacitive sensing readings.
Solution Approach 2:
The system introduces an intermediary measurement process that captures EMI characteristics separately from the capacitive sensing process. By measuring interference during dedicated time portions and using this intermediate data to adjust and clean the primary sensing measurements, the system effectively mediates between the EMI-generating display components and the sensitive proximity sensing components without requiring physical separation.
3Object-affected harmful factors
If shielding components are added to the device package, then EMI protection is improved, but manufacturing cost increases
Solution Approach 1:
The system replaces mechanical/physical EMI protection methods (such as shielding components and spatial distancing) with an electrical/software-based solution. By implementing interference sensing and compensation algorithms that operate on the sensed signals, the system achieves EMI protection through signal processing rather than through additional physical components, thereby reducing manufacturing complexity and cost.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the accuracy of positional information determination by minimizing the impact of EMI and reducing system costs and size by integrating interference sensing into the display device's operation.
Implementation Method 1
Many commercially available proximity sensor devices utilize one or more electrical techniques to determine the presence, location and/or motion of an input object, such as a capacitive or a resistive sensing technique
Implementation Method 2
these useful electrical sensing techniques are susceptible to interference, such as electromagnetic interference (EMI), commonly generated by the other supporting components, such as liquid crystal display (LCD) components
Data Source
AI summary
Embodiments of the present invention generally provide a method and system for sensing interference in a display device having integrated input sensing. In various embodiments of the invention, input sensing performed on one or more rows of common electrodes may be operated for interference sensing, and, during the blanking period, some or all of the common electrodes may be operated for interference sensing. Interference measurements acquired during blanking periods may be used to increase the accuracy with which input sensing is performed, for example, by establishing one or more baseline interference values and/or determining that one or more common electrodes should be driven at a different frequency. In some embodiments, all of the common electrodes may be operated for interference sensing during a blanking period, while in other embodiments a portion of the common electrodes (e.g., one-third, one-half, etc.) may be operated for interference sensing during a blanking period.