Display Apparatus Overdrive Voltage for Low Grayscale Stain Reduction
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Solution Overview
Problem
Current display apparatuses suffer from stains in low grayscale areas due to current leakage in light emitting elements, which deteriorates display quality and reduces the lifetime of pixel circuits.
Innovation Solution
The display apparatus employs an overdriven high power voltage in the initial period of the emission duration, selectively applied to specific color light emitting elements, to enhance pixel uniformity in low grayscale images, reduce light emitting delay, and prevent or reduce the decrease in the lifetime of these elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard power voltage is applied to light emitting elements, then the display apparatus operates normally, but current leakage causes stains in low grayscale areas and deteriorates display quality
Solution Approach 1:
The patent applies a preliminary high power voltage in the initial period before the light emitting element emits light. This overdrive voltage compensates for the light emitting delay and ensures uniform emission from the start, preventing stains in low grayscale areas. The preliminary action is taken before the harmful effect (current leakage causing stains) can manifest.
Solution Approach 2:
The patent changes the power voltage parameter dynamically - applying a high power voltage (overdrive level) during the initial period and then switching to a normal power voltage. This parameter change allows the light emitting element to overcome its delay characteristic and achieve uniform emission, eliminating the stain problem while maintaining normal operation.
2Reliability
If a high power voltage is continuously applied to compensate for light emitting delay, then pixel uniformity improves, but the lifetime of the light emitting element decreases
Solution Approach 1:
The patent applies high power voltage periodically - only during the initial period before light emission begins. After this initial overdrive period, the voltage returns to normal levels. This periodic application of high voltage compensates for light emitting delay without continuously stressing the light emitting element, thereby extending its lifetime while maintaining pixel uniformity.
Solution Approach 2:
The high power voltage is applied preliminarily only when needed (during the initial delay period) and then discontinued. This preliminary overdrive action compensates for the light emitting delay without subjecting the light emitting element to continuous high voltage stress, thus resolving the contradiction between improving uniformity and extending lifetime.
3Reliability
If selective overdrive voltage is applied to specific color light emitting elements, then light emitting delay is reduced and pixel uniformity enhances, but device complexity increases
Solution Approach 1:
The patent applies overdrive voltage selectively to specific color light emitting elements (e.g., green subpixels) that have longer emission delays, while normal voltage is applied to other elements. This localized approach targets only the elements needing compensation, reducing overall control complexity compared to applying overdrive to all elements uniformly.
Solution Approach 2:
The patent dynamically adjusts the power voltage based on the specific requirements of different color light emitting elements. The control system identifies which elements need overdrive compensation and applies high voltage only to those, creating a dynamic and adaptive control strategy that balances performance improvement with complexity management.
Data Source
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AI summary
A display apparatus includes a display panel and a power voltage generator. The display panel includes pixel circuits including a first light emitting element and a second light emitting element. The power voltage generator applies a high power voltage to first electrodes of the first light emitting element and the second light emitting element, a first low power voltage to a second electrode of the first light emitting element and a second low power voltage to a second electrode of the second light emitting element. The high power voltage has high level, the first low power voltage has low level and the second low power voltage has high level during an emission duration of a first frame. The high power voltage has the high level, the first low power voltage has high level and the second low power voltage has low level during an emission duration of a second frame.