Pixel Circuit Initialization Voltage Pulse for Variable Frame Rate Luminance

Solution Overview

Problem

Display devices operating in variable frame mode experience a decrease in luminance and deterioration of image quality due to differences in initialization periods between low-frequency and high-frequency regions, leading to suboptimal image rendering.

Innovation Solution

A pixel design that includes a light emitting element, transistors, and a storage capacitor, where an initialization voltage with a pulse component is applied during the data writing period to ensure consistent charging and minimize the impact of frequency variations, thereby maintaining image quality across different frame rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If variable frame mode is implemented to prevent tearing phenomenon, then image synchronization is improved, but luminance decrease and image quality deterioration occur due to initialization period differences

Engineering Contradiction:

Improveimage synchronizationVSAvoidluminance

Core Design Contradiction:

ReliabilityVSIllumination intensity

Solution Approach 1:

The pixel circuit dynamically adjusts the initialization voltage level based on the frame rate. During high-frequency periods, a higher initialization voltage (second voltage level) is applied to ensure rapid capacitor charging and maintain luminance, while during low-frequency periods, a lower initialization voltage (first voltage level) is used. This dynamic adaptation resolves the contradiction by making the initialization process frequency-dependent.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the voltage parameter of the initialization signal based on operating conditions. By switching between two voltage levels (first voltage level and second voltage level) according to the frame rate, the system optimizes both image synchronization and luminance maintenance, preventing the deterioration that occurs with fixed initialization parameters.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If initialization period is extended to ensure capacitor charging in high-frequency region, then image quality is maintained, but frame rate variability and synchronization capability are reduced

Engineering Contradiction:

Improveimage qualityVSAvoidframe rate variability

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The pixel circuit dynamically adjusts the initialization voltage level based on the frame rate. During high-frequency periods, a higher initialization voltage (second voltage level) is applied to ensure rapid capacitor charging and maintain luminance, while during low-frequency periods, a lower initialization voltage (first voltage level) is used. This dynamic adaptation resolves the contradiction by making the initialization process frequency-dependent.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent applies periodic initialization pulses with varying voltage levels synchronized to the frame rate. During high-frequency operation, higher voltage pulses are applied periodically to ensure adequate charging within the shortened initialization period, while maintaining frame rate variability. This periodic adaptive action allows the system to maintain image quality across different frame rates.

Inventive Principle:

Principle #19Periodic action

3Illumination intensity

If initialization voltage level is increased to ensure rapid capacitor charging, then luminance is maintained, but energy consumption increases

Engineering Contradiction:

ImproveluminanceVSAvoidenergy consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent changes the voltage parameter of the initialization signal based on operating conditions. By switching between two voltage levels (first voltage level and second voltage level) according to the frame rate, the system optimizes both image synchronization and luminance maintenance, preventing the deterioration that occurs with fixed initialization parameters.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies periodic initialization pulses with varying voltage levels synchronized to the frame rate. During high-frequency operation, higher voltage pulses are applied periodically to ensure adequate charging within the shortened initialization period, while maintaining frame rate variability. This periodic adaptive action allows the system to maintain image quality across different frame rates.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS11663956B2Pixel, display device including the pixel, and method of driving the display device

Publication Date: 2023.05.30 SAMSUNG DISPLAY CO LTD

AI summary

A pixel includes: a light emitting element; a first transistor which drives the light emitting element; a second transistor electrically connected between a gate node of the first transistor and a data line; a third transistor electrically connected between a first node of the first transistor and an initialization voltage line; and a storage capacitor electrically connected between the gate node and the first node of the first transistor. Here, upon an operation in a variable frame mode, an initialization voltage is applied to the initialization voltage line, and the initialization voltage has a first voltage level. In addition, in a data writing period during which the storage capacitor is charged with an electric charge, the initialization voltage further includes a pulse voltage such that the initialization voltage has a second voltage level that is greater than the first voltage level.