Organic Light Emitting Display Gate Signal Overlap for Threshold Voltage Compensation
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Solution Overview
Problem
High-resolution organic light emitting display devices face display defects such as spots due to insufficient threshold voltage compensation periods, especially when driven at high frequencies or using demultiplexers, which reduce the time available for compensating the threshold voltage of driving transistors.
Innovation Solution
The organic light emitting display device applies odd-numbered and even-numbered group gate signals to pixel rows, with the odd-numbered group gate signal overlapping part of the even-numbered group gate signal, ensuring sufficient threshold voltage compensation time by dividing the compensation period into multiple sub-periods for each sub-pixel, thereby preventing image deviations and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the data signal is switched quickly by the demultiplexer to reduce wirings and output channels, then the device complexity is reduced, but the compensating period of the threshold voltage of the driving transistor is significantly reduced
Solution Approach 1:
The pixel rows are divided into two groups: odd-numbered pixel groups and even-numbered pixel groups. Each group is driven by separate gate signals (odd-numbered group gate signal and even-numbered group gate signal), allowing independent control and extended compensation periods for each group without increasing overall device complexity.
Solution Approach 2:
The gate driver alternates between applying odd-numbered group gate signals and even-numbered group gate signals to different pixel groups in a periodic manner. This periodic switching allows each pixel group to receive adequate compensation time while maintaining high-speed operation across the entire display.
2Productivity
If the display device is driven at high frequency, then the productivity is improved, but the compensation time for each sub-pixel is insufficient
Solution Approach 1:
By segmenting the pixel rows into odd and even groups with separate gate signal control, each group can be compensated during its dedicated time slot without compromising the overall high driving frequency. The segmentation allows parallel processing of compensation for different groups.
Solution Approach 2:
The threshold voltage compensation is performed in advance during the compensation period before the emission period begins. By applying the gate signals and data signals in a specific sequence, the compensation is completed preliminarily, ensuring that the driving transistor is ready for high-frequency operation without sacrificing compensation quality.
3Speed
If the compensating period is reduced, then the device can operate at higher speeds, but display defects such as spots appear
Solution Approach 1:
Segmenting the display into odd and even pixel groups allows each segment to receive adequate compensation time despite fast overall switching. The separate gate signals ensure that compensation is properly performed in each segment, preventing display defects while maintaining high-speed operation.
Solution Approach 2:
The gate driver continuously alternates between odd and even group gate signals, ensuring that compensation actions are continuously performed across all pixel groups without interruption. This continuous alternating action maintains both high speed and high reliability by ensuring no pixel group is left uncompensated.
Data Source
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AI summary
An organic light emitting display device includes a display panel including pixel groups, each including a plurality of sub-pixels for each of pixel rows. A gate driver is configured to sequentially provide an initialization signal to the pixel rows, to provide a first group gate signal to first pixel groups of the pixel groups, to provide a second group gate signal overlapping at least a part of the first group gate signal to second pixel groups of the pixel groups, to sequentially provide the first group gate signal to the pixel rows, and to sequentially provide the second group gate signal to the pixel rows. An emission control driver is configured to sequentially provide an emission control signal to the pixel rows. A data driver is configured to output a data voltage. A data divider is configured to selectively provide the data voltage to data lines connected to the sub-pixels.