OLED Pixel Circuit IR Drop Compensation via Segmented Reference Voltage
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Solution Overview
Problem
Existing OLED display technologies face issues with pixel driving signal voltage deviations due to layout IR drops, leading to non-uniform image luminance across the display area, which are difficult to compensate for with complex pixel compensation circuits or separate reference voltage lines.
Innovation Solution
The proposed pixel circuit uses a data signal source to provide both the reference voltage and data signal voltage through a data line, with specific phases for setting up the reference voltage and charging, thereby avoiding IR drops and ensuring accurate voltage charging for the hold capacitor, independent of the DC power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the reference voltage is provided by the DC power supply, then the circuit structure is simple, but the IR drop on the power supply line causes voltage deviation and non-uniform luminance
Solution Approach 1:
The patent segments the reference voltage provision into two independent parts: a dedicated reference voltage line separate from the DC power supply line. This segmentation allows the reference voltage to be delivered without suffering from the IR drops that affect the main power supply line, thereby resolving the contradiction between circuit simplicity and voltage uniformity.
Solution Approach 2:
The patent introduces an intermediary reference voltage line that acts as a separate transmission path for delivering reference voltage to the hold capacitor. This intermediary path avoids the harmful IR drops of the main power supply line while maintaining circuit functionality, thus improving voltage uniformity without significantly complicating the overall circuit structure.
2Manufacturing precision
If a pixel compensation circuit is used to compensate for IR drop, then voltage uniformity is improved, but the circuit becomes complex
Solution Approach 1:
The patent extracts the reference voltage delivery function from the main power supply line and places it on a separate dedicated line. This extraction eliminates the need for complex compensation circuits by addressing the IR drop issue at its source through structural separation, thereby improving voltage uniformity while avoiding the complexity of active compensation mechanisms.
3Manufacturing precision
If a separate line is used for providing reference voltage, then IR drop is avoided, but the layout becomes complex
Solution Approach 1:
The patent merges the reference voltage line with the data line in terms of physical routing and resource sharing. Both the reference voltage and data signal are transmitted through the same data line infrastructure, which simplifies the layout by avoiding the need for completely separate physical wiring paths, thus achieving voltage uniformity without excessive layout complexity.
Data Source
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AI summary
The present invention discloses a pixel circuit and a driving method thereof, a display device. The pixel circuit comprises a reference voltage set up sub-circuit, a charging sub-circuit and a driving sub-circuit; the reference voltage set up sub-circuit and the charging sub-circuit being connected with the driving sub-circuit respectively, the reference voltage set up sub-circuit being used for, within a first period of time, providing for the driving sub-circuit, the charging sub-circuit being used for, within a second period of time, providing for the driving sub-circuit a data signal voltage; the driving sub-circuit comprising a driving transistor for driving the light emitting device to emit light, and a first capacitor for maintaining the reference voltage and the data signal voltage; within a third period of time, the first capacitor discharging so that the driving transistor is turned on to drive the light emitting device to emit light.