OLED Driving Transistor Compensation for Luminance Uniformity
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Solution Overview
Problem
Conventional organic light emitting displays using voltage programming techniques suffer from non-uniform luminance due to deviations in mobility and threshold voltage of driving transistors, while current programming techniques require a considerable amount of time to charge data lines, limiting their suitability for high-quality and high-resolution displays.
Innovation Solution
An organic light emitting display that rapidly charges data voltage using a voltage programming technique, compensating for deviations in driving transistor characteristics by employing a current programming technique, which involves a data line, scan line, switching elements, and capacitive elements to control the current and voltage supplied to the Organic Light Emitting Diode (OLED).
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If voltage programming technique is used, then charging time is reduced, but luminance uniformity deteriorates due to transistor parameter deviations
Solution Approach 1:
The patent changes the programming parameter from voltage to current. By programming current instead of voltage, the system compensates for transistor parameter deviations (threshold voltage and mobility variations) while maintaining fast charging speed. This parameter transformation resolves the contradiction between charging speed and luminance uniformity.
Solution Approach 2:
The patent introduces a feedback mechanism where the programming current is adjusted based on the actual transistor characteristics. By measuring and compensating for threshold voltage and mobility deviations, the system achieves uniform luminance while maintaining rapid charging, thus resolving the technical contradiction.
2Manufacturing precision
If current programming technique is used, then luminance uniformity is improved, but charging time increases considerably
Solution Approach 1:
The patent transforms the programming parameter from current to voltage. By using voltage programming, the system achieves fast charging comparable to conventional techniques while incorporating compensation mechanisms that maintain luminance uniformity. This parameter change resolves the contradiction between uniformity and charging time.
3Productivity
If conventional voltage programming is used, then charging speed is maintained, but display quality deteriorates due to non-uniform luminance
Solution Approach 1:
The patent incorporates feedback compensation for transistor parameter deviations (threshold voltage and mobility). By continuously monitoring and adjusting based on actual transistor characteristics, the system maintains fast charging speed while achieving uniform luminance, thus resolving the contradiction between productivity and display quality.
Solution Approach 2:
The patent modifies the programming approach by transforming from simple voltage programming to voltage programming with current compensation. This parameter transformation enables the system to maintain charging speed while improving display quality through compensation for manufacturing variations.
Data Source
AI summary
An organic light emitting display, suitable for a high quality and high resolution display device, rapidly charges a data voltage using a voltage programming technique, after compensating for a deviations in the threshold voltage and mobility of a driving transistor using a current programming technique. The organic light emitting display includes: a data line supplying a data signal; a scan line supplying a scan signal; a first switching element, electrically coupling its control electrode to the scan line, transferring the data signal supplied from the data line; a driving transistor, electrically coupling its control electrode to the first switching element, controlling a driving current of a first voltage line; a first capacitive element electrically coupled between the first switching element and the control electrode of the driving transistor; an Organic Light Emitting Diode (OLED), electrically coupled between the driving transistor and a second power voltage line, displaying an image by a current supplied from the driving transistor; and a fourth switching element compensating for deviations of characteristics of the driving transistor by supplying a current of the first current line to the driving transistor.