Display Flicker Reduction via Voltage Compensation
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Solution Overview
Problem
Display devices experience flicker issues when the driving frequency is changed, particularly in frequency variable modes where the timing of initializing the first electrode voltage of the light emitting element is not constant, leading to undesirable luminance and flicker occurrences.
Innovation Solution
A display device design that includes a pixel connected to scan lines and a data line, featuring a light emitting element and a storage capacitor, with a sensing unit to sense the first electrode voltage in an initial blank period after frequency change, and a data driver applying a compensation data voltage based on the sensed voltage to prevent flicker by maintaining desired luminance without initializing the first electrode voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first electrode voltage is initialized when data voltage is supplied to the storage capacitor in frequency variable mode, then the storage capacitor is properly charged, but flicker occurs due to non-constant initialization timing
Solution Approach 1:
The patent inverts the conventional initialization approach by not initializing the first electrode voltage during frequency variable mode operation. Instead of applying initialization voltage to the first electrode when frequency changes, the system maintains the existing voltage state, thereby avoiding flicker caused by timing variations in initialization while still achieving proper luminance control through alternative means.
Solution Approach 2:
The patent changes the voltage initialization parameter conditionally based on operating mode. In normal mode, the first electrode voltage is initialized when data voltage is supplied to the storage capacitor. In frequency variable mode, this initialization is suppressed. This parameter change resolves the contradiction by adapting the initialization behavior to the specific operating conditions.
2Adaptability or versatility
If the driving frequency is changed to non-integer multiples, then frequency flexibility is improved, but flicker and luminance inconsistency occur
Solution Approach 1:
The patent implements dynamic control of the initialization process based on the detected operating mode. The system dynamically adjusts whether to initialize the first electrode voltage by detecting whether the display is operating in normal mode or frequency variable mode. This dynamic adaptation enables the system to maintain luminance consistency across different frequency conditions while preserving frequency flexibility.
3Manufacturing precision
If the first electrode voltage is initialized during frequency variable mode, then voltage compensation is achieved, but flicker occurs due to timing variations
Solution Approach 1:
The patent applies different voltage control strategies to different operating conditions. Specifically, the initialization of the first electrode voltage is applied locally to normal mode operation but suppressed in frequency variable mode. This localized quality adjustment resolves the contradiction by providing precise voltage control where needed (normal mode) while avoiding flicker in frequency variable mode through selective suppression of initialization.
Data Source
AI summary
A display device includes: a pixel connected to a first scan line, a second scan line, and a data line, and including a light emitting element and a storage capacitor; and a timing controller configured to drive the pixel in a normal mode in which a driving frequency is maintained constant or a frequency variable mode according to a variable frequency signal supplied from outside, wherein in the normal mode, a first electrode voltage of the light emitting element is initialized in response to a data voltage being supplied to the storage capacitor, and wherein in the frequency variable mode, the first electrode voltage of the light emitting element is not initialized in response to the data voltage being supplied to the storage capacitor.