Display Panel Compensation Circuit for IR Drop Uniformity
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Solution Overview
Problem
Existing OLED display devices suffer from uneven display brightness due to IR drops in power supply voltage distribution, which worsens with larger display areas, causing display unevenness and inconsistencies in image display.
Innovation Solution
A display panel design that includes a compensation unit between the driving transistor and the light emitting unit, controlled to disconnect the energy storage unit from the light emitting unit during the compensation period, ensuring a black state and effectively eliminating the IR drop influence, thereby maintaining pixel circuit stability and reducing display unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the display area of the OLED display device is increased, then the display coverage is improved, but the display unevenness becomes more serious due to IR drops in power supply voltage distribution
Solution Approach 1:
The patent applies preliminary action by performing compensation for the driving transistor threshold voltage before the light emitting phase. The compensation unit measures and compensates for threshold voltage variations during a compensation phase that precedes the actual display phase, ensuring that pixel circuits are pre-adjusted to account for IR drops and other variations before light emission begins. This preliminary compensation ensures uniform display across large areas without affecting the final display brightness.
2Manufacturing precision
If a compensation unit is added to eliminate IR drop effects, then display uniformity is improved, but the pixel circuit complexity increases
Solution Approach 1:
The compensation unit is designed with multi-functionality to reduce overall circuit complexity. The same compensation unit circuit structure is universally applied across all pixel circuits in the display, allowing standardized fabrication and simplifying design. The compensation unit serves multiple purposes: measuring threshold voltage, storing compensation voltage, and controlling the light emitting phase, thereby achieving uniform display without requiring entirely separate compensation circuits for each pixel.
Solution Approach 2:
The patent merges the compensation function with the existing pixel circuit structure. The compensation unit is integrated into the pixel circuit alongside the driving transistor, energy storage unit, and light emitting unit, sharing common nodes and control signals. This merging approach allows the compensation functionality to be added without completely redesigning the pixel circuit, thereby limiting the increase in complexity while achieving display uniformity.
3Manufacturing precision
If the compensation unit disconnects the energy storage unit from the light emitting unit during compensation period, then IR drop influence is eliminated, but the control complexity increases
Solution Approach 1:
The patent implements periodic action by dividing the operating cycle into distinct phases: a compensation period and a light emitting period. During the compensation period, the compensation unit disconnects the energy storage unit from the light emitting unit to accurately measure and compensate for threshold voltage without light emission interference. During the light emitting period, the connection is restored for normal display operation. This periodic switching, controlled by timing signals, simplifies the control logic by using clear phase-based control rather than continuous complex regulation.
Data Source
AI summary
A display panel, a display device and a control method for a display panel are provided. The display panel comprises a plurality of pixel circuits, each of which includes a driving transistor, an energy storage unit, a data writing unit, a reset unit, a compensation unit, and a light emitting unit. The display panel further comprises a driving circuit, which is used to control the compensation unit during a compensation period so as to disconnect the other terminal of the energy storage unit from one terminal of the light emitting unit, so that the light emitting unit in each of the pixel circuits is in an extinguished state.