OLED Pixel Circuit Overlapping Compensation With Data Writing
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Solution Overview
Problem
In high-resolution display devices, especially those using organic light emitting diodes (OLEDs), the time required for compensating the threshold voltage of driving transistors restricts the number of pixels that can be multiplexed, leading to reduced frame rates and increased data preparation and writing times.
Innovation Solution
The display device incorporates a pixel structure with a data line, a gate line, and a pixel comprising an OLED, a low voltage source, a data select switch, a reference voltage switch, an emission switch, and a driving transistor. The compensation period for the pixel overlaps with the data writing period of a previous row, allowing for efficient threshold voltage compensation without extending the overall data preparation and writing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of pixels is increased to achieve high resolution, then the display resolution is improved, but the time allocated for data preparation and writing is reduced
Solution Approach 1:
The patent performs threshold voltage compensation during the data writing period of the previous row through preliminary action. By using a reference voltage switch to apply reference voltage to the gate of the driving transistor during the compensation period, which overlaps with the data writing period of the previous row, the compensation is completed before the current row's data writing begins, thus not extending the overall data preparation and writing time.
Solution Approach 2:
The patent introduces a time dimension overlap between compensation operations and data writing operations. By allowing the compensation period of the current row to overlap with the data writing period of the previous row, the patent effectively utilizes idle time resources and achieves parallel processing, thereby maintaining high resolution while preventing time loss.
2Reliability
If threshold voltage compensation is performed using reference voltage, then the driving transistor performance is stabilized, but the compensation time is extended
Solution Approach 1:
The patent merges the compensation period with the data writing period of the previous row. By configuring the reference voltage switch to operate during the compensation period which overlaps with the previous row's data writing period, the patent combines two operations in time, achieving both threshold voltage stabilization and time efficiency simultaneously.
Solution Approach 2:
The patent ensures continuous useful action by overlapping the compensation period with the data writing period. Instead of having sequential operations that would create idle time, the patent maintains continuous utilization of the pixel circuit resources, where compensation for the current row occurs while data writing for the previous row is still in progress.
3Speed
If the frame rate is increased for high resolution displays, then the display refresh speed is improved, but the time for data preparation and writing is further reduced
Solution Approach 1:
By performing threshold voltage compensation as a preliminary action during the overlapping period with the previous row's data writing, the patent prepares the pixel circuit in advance for the current row's operation. This preliminary compensation enables faster subsequent operations and supports higher frame rates by eliminating sequential time delays.
Solution Approach 2:
The patent utilizes the time dimension creatively by allowing overlap between compensation and data writing operations. This dimensional approach to time management enables the system to achieve higher frame rates by effectively parallelizing operations that would traditionally be sequential, thus increasing the overall processing speed.
Data Source
AI summary
Embodiments relate to a display device including pixels that compensate a threshold voltage of a driving transistor, the pixels arranged in a plurality of rows. The gate of the driving transistor of each pixel is coupled to a pixel data switch and a reference voltage switch, configured to selectively provide pixel data provided via a data line and a reference voltage provided via a separate reference voltage line to the gate of the driving transistor, respectively. As pixel data and the reference voltage are provided to the driving transistor via separate lines, the compensation period of the pixel may overlap in time with a data writing period of pixels of a previous row of the display device, increasing the rate at which the display device is able to program the pixels of each row.