Reference Pixel Circuit for Luminance Correction in OLED Displays
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Solution Overview
Problem
Existing organic light-emitting display devices face issues with luminance unevenness due to temporal degradation, where current measuring circuits struggle to accurately correct luminance variations across pixels, especially in varying measurement environments, leading to inaccuracies and prolonged correction times.
Innovation Solution
A display device incorporating a current generation circuit, pixel circuits, a driving unit, a measuring unit using an integrating circuit, and a correction unit that measures and corrects degradation by generating a reference current and measuring differences between adjacent pixel currents, thereby accurately adjusting luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current measuring circuit is provided for each column to measure pixel currents, then luminance correction can be performed, but measurement accuracy deteriorates due to environmental variations (temperature, noise) affecting the measured currents
Solution Approach 1:
A reference pixel circuit is introduced as an intermediary element that experiences the same environmental conditions as the actual pixel circuits but does not display images. This reference circuit serves as a mediator to capture environmental effects separately, allowing these effects to be subtracted from the measured pixel currents to obtain accurate degradation values free from environmental interference.
Solution Approach 2:
The reference pixel circuit is designed as an identical copy of the actual pixel circuits in terms of structure and components, ensuring it experiences the same environmental conditions. By copying the pixel circuit configuration and using it solely for reference measurements, the system can isolate and remove environmental variations from the luminance correction calculation.
2Reliability
If a noise measurement step is added to check for noise levels before correction, then measurement reliability improves, but correction time increases due to the additional measurement step and repetition
Solution Approach 1:
The reference pixel circuit continuously operates alongside the actual pixel circuits during normal display operation, accumulating data about environmental effects in real-time. This continuous measurement eliminates the need for separate noise measurement steps, as the reference circuit provides ongoing environmental compensation data that can be immediately applied to correct luminance variations.
Solution Approach 2:
The reference pixel circuit performs preliminary measurement of environmental effects continuously during normal operation, so that when luminance correction is needed, the compensation data is already available. This preliminary and continuous action by the reference circuit eliminates the need for time-consuming separate noise measurement and validation steps.
Data Source
AI summary
A current generation circuit that generates a current that serves as a current, a plurality of pixels arranged adjacent to one another, a source driver that supplies the same current to each of the plurality of pixels, an integrating circuit that measures the current, an ADC that converts a result of the measurement into digital data, and a control circuit that corrects degradation of other pixels 11 on the basis of the digital data obtained by the ADC using, as the reference, the current that serves as the reference.