Display Panel Dual-Sided EVSS Power Routing for Uniform Luminance
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Solution Overview
Problem
Organic light emitting displays experience luminance non-uniformity due to variations in the driving voltage supplied to sub-pixels, which is influenced by the distance from the power supply source.
Innovation Solution
A display device with a power supply system that includes a first and second power line to apply EVSS power, a timing controller to control power application, and EVSS buffers with TFT switches to stabilize the EVSS power by alternating between high and low potential voltages during active and vertical blank periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If EVSS power is supplied from a single power supply source, then the device complexity is reduced, but voltage variation occurs due to distance from the power supply source
Solution Approach 1:
The single power supply source is segmented into two separate power supply sources (first power supply source and second power supply source) positioned at opposite ends of the display panel. This segmentation allows voltage to be supplied from both directions, reducing voltage variation across the panel while maintaining a relatively simple overall structure.
2Stability of the object's composition
If EVSS power is supplied continuously at high potential, then the luminance uniformity is maintained during active period, but voltage variation accumulates during vertical blank period
Solution Approach 1:
The power supply operates in periodic cycles, alternating between first EVSS power and second EVSS power during the vertical blank period. This periodic switching prevents voltage variation accumulation by periodically resetting the voltage levels, while maintaining luminance uniformity during the active display period.
Solution Approach 2:
During the vertical blank period before the active display period, the system performs preliminary voltage adjustment by supplying alternating first and second EVSS power. This preliminary action prevents voltage variation from accumulating before the next active period begins, ensuring luminance uniformity is maintained.
Data Source
AI summary
A display device includes a display panel including pixels connected to a plurality of power input lines and receiving EVSS power, a first power line connected to one end of each of the power input lines to apply first EVSS power, a second power line connected to the other end of each of the power input lines to apply second EVSS power having the same electric potential as that of the first EVSS power, and a power supply configured to apply the first EVSS power through the first power line or to apply the second EVSS power through the second power line.