Digital Display Pixel Luminance Control Against Refresh-Rate Flicker

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Solution Overview

Problem

Digital displays using pulse-width modulated signals for luminance control experience flickering issues when the refresh rate varies, leading to inconsistent brightness due to non-integer multiples of the display refresh rate.

Innovation Solution

Implement spatial and/or temporal averaging by supplying half of the pixel rows with pulse-width modulated signals of opposite phases, ensuring that half of the pixel rows have relatively higher and lower luminance in each frame, thereby maintaining uniform luminance perception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If pulse-width modulated signals are used for luminance control, then luminance control precision is improved, but flickering occurs when refresh rate varies

Engineering Contradiction:

Improveluminance control precisionVSAvoidbrightness consistency

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent divides the pixel rows into two separate groups: first pixel rows and second pixel rows. Each group is controlled by independent EM gate drivers that can be supplied with pulse-width modulated signals of opposite phases. This segmentation allows the display to mitigate flickering effects by ensuring that when one group is at a higher luminance state, the other group compensates, thereby maintaining overall brightness consistency during refresh rate variations.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies opposite phases to the pulse-width modulated signals supplied to different pixel row groups. Specifically, when the first EM gate driver receives a signal with a certain phase, the second EM gate driver receives a signal with the opposite phase. This inversion strategy ensures that luminance fluctuations in one group are counterbalanced by the other group, eliminating the flickering effect while maintaining precise luminance control.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If refresh rate is varied to improve adaptability, then display versatility is improved, but luminance consistency deteriorates

Engineering Contradiction:

Improvedisplay versatilityVSAvoidluminance consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a dynamic control system where the luminance controller can independently adjust the duty cycles of pulse-width modulated signals supplied to different pixel row groups. This dynamic adaptability allows the display to maintain consistent luminance perception across varying refresh rates, as the system can real-time compensate for fluctuations caused by non-integer multiple relationships between PWM frequency and refresh rate.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12374278B2Pixel luminance for digital display

Publication Date: 2025.07.29 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

A digital display includes a plurality of pixel rows. For each pixel row, the digital display includes an EM gate driver configured to supply the pixel row with a luminance-controlling signal during each of a plurality of image frames. A luminance controller is configured to instruct the EM gate drivers to supply a pulse-width modulated signal to the plurality of pixel rows. Some pixel rows are supplied with a pulse-width modulated signal starting with an on pulse, and some pixel rows are supplied with a pulse-width modulated signal starting with an off pulse, on the same or different image frames.