Mid-Frame Blanking for Touch and Pen Sensing Noise

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Solution Overview

Problem

The integration of components in mobile devices leads to electrical interference, affecting the accuracy of touch and pen sensing due to noise generated by the display driving pixels, which degrades the signal-to-noise ratio (SNR) and user experience.

Innovation Solution

Incorporating mid-frame blanking intervals within the frame period allows the sensing circuitry to operate during quieter periods, improving the signal-to-noise ratio by distributing the vertical-blanking interval throughout the frame period, thereby enhancing the accuracy of touch and pen measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the display continuously drives pixels to update the display, then the display refresh rate is maintained, but electrical interference and noise increase, degrading touch and pen sensing accuracy

Engineering Contradiction:

Improvetouch and pen sensing accuracyVSAvoiddisplay noise

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent implements periodic blanking intervals within the frame period where pixel driving is temporarily suspended. These periodic pauses create noise-free windows for capacitive sensing operations, allowing the system to alternate between display updating and sensing modes in a cyclic manner, thereby resolving the conflict between continuous display refresh and accurate sensing

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The frame period is segmented into multiple sub-intervals: active pixel driving intervals and blanking intervals. By dividing the continuous frame period into discrete segments with different functions (display updating vs. sensing), the patent enables simultaneous optimization of both display performance and sensing accuracy without requiring complete separation of the two functions

Inventive Principle:

Principle #1Segmentation

2Measurement precision

If mid-frame blanking intervals are inserted to reduce display noise, then sensing accuracy improves, but the frame period is extended

Engineering Contradiction:

Improvesensing accuracyVSAvoidframe period

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

Instead of implementing complete frame blanking which would double the frame period, the patent applies partial blanking by inserting only mid-frame blanking intervals. This partial action provides sufficient noise reduction for accurate sensing while maintaining the overall frame rate, avoiding the excessive time loss that would result from complete frame suspension

Inventive Principle:

Principle #16Partial or excessive action

Data Source

PatentEP3566116B1Mitigating display noise for touch and pen sensing

Publication Date: 2021.03.03 MICROSOFT TECHNOLOGY LICENSING LLC

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AI summary

A display device includes a display controller and a timing controller to drive frames at a frame rate onto a display. The display device may include sensor circuitry to detect a signal from a pen. The signal from the pen includes a sync signal indicative of a repetition rate of the signal. In one embodiment, the sync signal and the display timer are asynchronous. The sensor circuitry is configured to sense the signal from the pen during sensing windows, where timing of the sensing windows is based on the repetition rate. In one embodiment, the display controller is configured to pause driving a frame onto the display during the sensing windows.