VRR Display Driving Circuit for Stable Luminance Transitions

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Solution Overview

Problem

The change in refresh rate in electroluminescent display devices using a variable refresh rate (VRR) mode can cause unnatural perception of luminance differences, which is undesirable for viewers.

Innovation Solution

The display device employs a pixel circuit with a driving transistor, compensation transistor, and bias transistors that dynamically control bias voltages before and after switching refresh rates, using a refresh frame period and a hold frame period to maintain consistent luminance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the refresh rate is changed in VRR mode, then power consumption is reduced or driving speed is adjusted, but luminance difference occurs that is perceived by viewers

Engineering Contradiction:

Improvepower consumptionVSAvoidluminance consistency

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

The pixel circuit applies a bias voltage to the electroluminescent device before the refresh rate change occurs. This preliminary action prepares the device by adjusting its electrical state in advance, so that when the refresh rate changes, the luminance remains consistent and no perceptible difference occurs to viewers.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention changes the voltage parameter of the electroluminescent device by applying a bias voltage through the pixel circuit. This parameter change adjusts the electrical state of the device to compensate for the effects of refresh rate changes, maintaining luminance consistency while enabling power consumption reduction or driving speed adjustment.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If the refresh rate is updated frequently, then image quality is maintained, but power consumption increases

Engineering Contradiction:

Improveimage qualityVSAvoidpower consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The pixel circuit dynamically adjusts the bias voltage applied to the electroluminescent device based on the refresh rate. When the refresh rate is reduced, the bias voltage is adjusted to maintain image quality. This dynamic adaptation allows the system to lower power consumption while preserving acceptable image quality through intelligent voltage control.

Inventive Principle:

Principle #15Dynamics

3Use of energy by moving object

If the refresh rate is reduced for low-speed driving, then power consumption is reduced, but luminance perception becomes unnatural

Engineering Contradiction:

Improvepower consumptionVSAvoidvisual naturalness

Core Design Contradiction:

Use of energy by moving objectVSEase of operation

Solution Approach 1:

The pixel circuit applies a bias voltage in advance to counteract the potential luminance degradation that would occur during low-speed driving. This preliminary anti-action prevents the unnatural luminance perception from occurring in the first place, allowing the system to reduce power consumption while maintaining natural visual appearance.

Inventive Principle:

Principle #9Preliminary anti-action

Data Source

PatentUS12451075B2Driving circuit and display device using the same

Publication Date: 2025.10.21 LG DISPLAY CO LTD

AI summary

Disclosed is an electroluminescent display device using a variable refresh rate (VRR) mode. The purpose of the present disclosure is to reduce the occurrence of a difference in luminance at a time point of a refresh rate change, thereby preventing viewers from perceiving the variation of the refresh rate.