Buffer Transistor Pixel Pitch OLED Brightness Uniformity
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Solution Overview
Problem
In organic electroluminescent (OLED) display devices, brightness irregularities occur due to fluctuations in the threshold voltage and mobility of driving transistors and electro-optic elements, leading to uneven light emission across the screen, particularly exacerbated by waveform blunting of pulse signals in scanning lines, which affects the timing of transistor correction periods.
Innovation Solution
The implementation of a display device design where buffer transistors with maximum channel widths, equal to or greater than the pixel pitch, are used to output pulse signals for sampling video signals, and are arranged to suppress waveform blunting irregularities, ensuring consistent driving current and improved mobility correction, thereby stabilizing light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If buffer transistors with maximum channel widths are used to output pulse signals, then waveform blunting irregularities are suppressed and mobility correction is improved, but device complexity increases
Solution Approach 1:
The patent changes the channel width parameter of buffer transistors to maximum dimensions (equal to or greater than pixel pitch) to suppress waveform blunting. This parameter optimization improves signal integrity and mobility correction while maintaining brightness uniformity across the display panel.
2Stability of the object's composition
If the channel width of buffer transistors is increased to suppress waveform blunting, then light emission stability is improved, but area occupied by transistors increases
Solution Approach 1:
The patent positions buffer transistors at the intersection of scanning lines and signal lines, utilizing the two-dimensional layout space efficiently. By making channel width equal to or greater than pixel pitch, the transistors operate in an optimized dimensional configuration that improves light emission stability without excessive area occupation.
3Manufacturing precision
If pulse signal timing is optimized for mobility correction, then brightness irregularities are reduced, but device complexity increases
Solution Approach 1:
The patent implements mobility correction by applying correction pulses at specific timing periods before or during the display period. This preliminary action compensates for threshold voltage and mobility variations in advance, reducing brightness irregularities without requiring complex real-time control circuits.
Data Source
AI summary
A display device includes: a pixel array unit with pixel circuits disposed in matrix form, the pixel circuit including a driving transistor, an electro-optic element, a storage capacitor, and a sampling transistor, with the electro-optic element emitting light by generating a driving current based on information stored in the storage capacitor at the driving transistor to be applied to the electro-optic element; and a control unit, of which the output stage includes a buffer transistor, to output a pulse signal for driving the pixel array unit from the buffer transistor; wherein the pixel array unit and the control unit are formed with long laser beam irradiation to be scanned in the vertical direction or horizontal direction; and wherein with the control unit, the size of the buffer transistor is equal to or greater than the pixel pitch in the scanning direction of the laser beam.