OLED Driving Circuit Mobility Correction via Temporary Power Supply Voltage Boost
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Solution Overview
Problem
The existing display apparatuses with organic electroluminescence (EL) panels face challenges in maintaining uniform light luminance across pixels due to time-dependent deterioration of the I-V characteristic of organic EL elements and variations in transistor characteristics, leading to non-uniform image quality.
Innovation Solution
The display apparatus incorporates a power supplying section that temporarily raises the power supply potential of adjacent pixels' power supply lines during mobility correction, utilizing a sampling transistor, driving transistor, accumulating capacitor, and auxiliary capacitor to compensate for mobility variations among pixels, thereby reducing the time required for mobility correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mobility correction is performed to compensate for transistor characteristic variations among pixels, then uniformity of light luminance is improved, but the time required for correction increases
Solution Approach 1:
The patent applies preliminary action by performing mobility correction in advance during a dedicated correction period before the actual display period. The correction is executed by applying a correction voltage to the gate electrode of the driving transistor based on stored correction data, ensuring that transistor characteristic variations are compensated before image display begins. This allows the display to start immediately after correction without extending the overall operation cycle.
Solution Approach 2:
The patent implements periodic action by dividing the operation into distinct periods: a correction period for mobility correction and a display period for image output. The correction is performed periodically at the beginning of each frame cycle or at predetermined intervals, allowing the system to maintain uniformity without continuously adjusting parameters during display. This periodic approach minimizes interference with the display function while ensuring consistent luminance.
2Productivity
If the power supply potential is temporarily raised during mobility correction, then the correction speed is improved, but the power consumption increases
Solution Approach 1:
The patent applies periodic action by raising the power supply potential only during the mobility correction period and then returning it to the normal level during the display period. This temporary voltage increase accelerates the correction process by enhancing the charging/discharging speed of capacitors and the response of transistors during correction, while power consumption returns to normal levels during image display, thus balancing correction speed with overall power efficiency.
Solution Approach 2:
The patent implements dynamics by dynamically adjusting the power supply potential based on the operational phase: a higher potential is applied during mobility correction to accelerate the process, and a normal potential is maintained during display to conserve power. This dynamic voltage adjustment allows the system to optimize performance during correction without incurring continuous high power consumption during normal operation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for a reduction in the time needed for mobility correction, enabling higher speed driving and maintaining consistent light luminance across pixels, thus improving the display quality by compensating for variations in transistor characteristics and I-V characteristics.
Implementation Method 1
The organic EL element has a diode characteristic and utilizes a phenomenon that, if an electric field is applied to an organic thin film, then the organic thin film emits light
Implementation Method 2
an accumulating capacitor connected between an anode of the light emitting element and gate of the driving transistor and adapted to retain a predetermined potential
Implementation Method 3
an auxiliary capacitor connected between the anode of the light emitting element and a power supply line for an adjacent pixel and adapted to retain a predetermined potential
Data Source
AI summary
Disclosed herein is a display apparatus, including, a pixel array section including a plurality of pixels disposed in rows and columns, a number of power supply lines equal to the number of the rows of the pixels, each of the power supply lines being wired commonly to those of the pixels which are juxtaposed in a direction of a row, and a power supplying section adapted to supply a predetermined power supply potential to the pixels in the rows through the power supply lines.