Pixel Circuit Refresh Rate Control for Display Flicker Mitigation

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Solution Overview

Problem

Existing display technologies face challenges in achieving high pixel density, uniformity, and reduced flickering, as they often require trade-offs between programming speed, pixel pitch, and image uniformity, and are prone to flickering due to refresh rate-related darkening and brightening.

Innovation Solution

The use of a current divider within a pixel circuit, utilizing a storage capacitor and data line capacitance to divide a reference current, allowing for rapid discharge of the data line while maintaining small current through the driving transistor, and increasing refresh rate by displaying each frame multiple times, thereby reducing flickering perception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If additional lines and transistors are added to each pixel circuit for compensation, then image uniformity is improved, but pixel-pitch increases

Engineering Contradiction:

Improveimage uniformityVSAvoidpixel-pitch

Core Design Contradiction:

Manufacturing precisionVSLength of moving object

Solution Approach 1:

The patent combines the compensation function and programming function into a single shared data line, eliminating the need for separate compensation lines. The pixel circuit uses the same data line for both applying compensation voltages and programming display information, thereby reducing the number of lines and transistors while maintaining uniformity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The data line is designed to serve multiple functions: it acts as both a compensation voltage application line and a programming data line. By making the data line universal, the patent reduces the overall number of lines required in the display panel, thus decreasing pixel-pitch while maintaining compensation capabilities.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Speed

If high biasing current or initial charge is used to increase programming speed, then programming speed is improved, but image uniformity deteriorates

Engineering Contradiction:

Improveprogramming speedVSAvoidimage uniformity

Core Design Contradiction:

SpeedVSManufacturing precision

Solution Approach 1:

The patent applies compensation voltages to the pixel circuits before the actual programming operation. By pre-compensating for variations in transistor characteristics and then using moderate biasing currents for programming, the system achieves both good uniformity and acceptable programming speed without the need for excessively high currents that would compromise uniformity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent dynamically adjusts the biasing current and programming voltage based on the specific pixel circuit characteristics. By adapting the programming parameters to each pixel's needs rather than using fixed high current for all pixels, the system maintains uniformity across the display while achieving efficient programming.

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If refresh rate is increased to reduce flickering perception, then flickering is reduced, but power consumption increases

Engineering Contradiction:

Improveflickering perceptionVSAvoidpower consumption

Core Design Contradiction:

Object-affected harmful factorsVSUse of energy by moving object

Solution Approach 1:

The patent implements a duty cycle-based refresh approach where the display alternates between program phases and emission phases. By optimizing the timing and duration of these periodic phases, the system achieves reduced flickering at the perceived refresh rate while managing power consumption through controlled emission intervals rather than continuous operation.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent maintains continuous pixel circuit operation by keeping the display information stored in the pixel circuits during program phases, allowing the emission to continue or resume without complete interruption. This continuous action reduces flickering perception while minimizing the need for high power consumption during non-emission periods.

Inventive Principle:

Principle #20Continuity of useful action

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

This approach enables swift programming of pixel circuits, maintains uniformity, increases pixel density, and decreases the perception of flickering by enhancing refresh rate, allowing for higher display resolution and improved image stability.

Implementation Method 1

utilizing a storage capacitor and data line capacitance to divide a reference current

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS11790868B2Systems and methods for operating pixels in a display to mitigate image flicker

Publication Date: 2023.10.17 IGNIS INNOVATION

AI summary

Circuits for programming a circuit with decreased programming time are provided. Such circuits include a storage device such as a capacitor for storing display information and for ensuring a driving device such as a driving transistor drives a light emitting device according to the display information. The present disclosure provides driving schemes for decreasing flickering perceived while displaying video content by introducing idle phases in between in emission phases to increase the effective refresh rate of a display. Driving schemes are also disclosed for reducing the effects of cross-talk by ensuring that programming information is refreshed in a display array that utilizes a driver connected to multiple data lines via a multiplexer.