OLED Pixel Circuit Voltage Stabilization via Dual Supply Lines
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Solution Overview
Problem
Organic light-emitting display devices face variations in supply voltages, leading to deterioration in image quality due to resistance in conductive lines, resulting in non-uniform luminance and potential display failures.
Innovation Solution
The implementation of a configuration with a high-level supply voltage line, data line, scan signal line, emission control signal line, first and second supply voltage lines, and a specific transistor structure that transfers different voltages to the pixel circuit during distinct periods, with an additional transistor connected between the supply voltage lines to stabilize the voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional supply voltage line configuration is used, then the device structure is simple, but voltage variations occur due to resistance in conductive lines leading to non-uniform luminance
Solution Approach 1:
The supply voltage line is divided into multiple segments (first supply voltage line and second supply voltage line) that can be independently controlled. Each segment can supply voltage to different regions or at different times, reducing the impact of resistance-induced voltage drops in any single line and improving overall voltage stability across the display device.
2Reliability
If multiple supply voltage lines with different voltages are used, then voltage variations are reduced, but the transistor structure and control complexity increase
Solution Approach 1:
The pixel circuit performs preliminary actions by storing compensation values in storage capacitors during initialization and compensation periods. This preliminary compensation for expected voltage drops allows the circuit to maintain accurate drive currents during the emission period, ensuring luminance uniformity without requiring complex real-time adjustment mechanisms.
Solution Approach 2:
The pixel circuit dynamically adjusts its operation by switching between different supply voltage lines at different times. The first and second supply voltage lines are selectively connected to the pixel circuit based on the operating period (initialization, compensation, or emission), allowing the circuit to adapt to different voltage requirements and reduce luminance non-uniformity.
3Reliability
If the additional transistor is connected between supply voltage lines, then voltage margin is maintained, but the pixel circuit complexity increases
Solution Approach 1:
The additional transistor serves multiple functions: it acts as a switching element for connecting different supply voltage lines, functions as part of the voltage selection mechanism during different periods, and contributes to the overall voltage stabilization mechanism. This multi-functionality reduces the need for separate dedicated components for each function.
Data Source
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AI summary
Provided is an organic light-emitting display (OLED) device. The organic light-emitting display (OLED) device includes at least a pixel circuit comprising an organic light-emitting diode and a driving transistor for driving the organic light-emitting diode; a first supply voltage line transferring a first voltage to the pixel circuit; at least a second supply voltage line transferring the first voltage to the pixel circuit during a first period and transferring a second voltage to the pixel circuit during a second period; and a switch connected between the first supply voltage line and the second supply voltage line, wherein the switch is turned on during the first period and turned off during the second period. Accordingly, it is possible to provide a structure for reducing variations in supply voltages of an organic light-emitting display device.