Pixel Circuit Removing Reference Voltage Line
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Solution Overview
Problem
Existing display devices, particularly organic light emitting display devices, face challenges in achieving high-resolution pixel layouts due to the necessity of a reference voltage line for internal compensation methods, which limits design flexibility.
Innovation Solution
The proposed solution involves a pixel circuit that eliminates the need for a reference voltage line by applying a black data voltage to the source node of the driving element through a data voltage line during the initialization period, allowing for a high-resolution pixel layout design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If internal compensation method is used with reference voltage line, then driving element threshold voltage can be compensated, but pixel layout design is limited and resolution is reduced
Solution Approach 1:
The patent extracts and removes the reference voltage line from the pixel circuit structure. Instead of using a separate reference voltage line to apply reference voltage to the source node, the invention applies the reference voltage (black data voltage) through the existing data voltage line, thereby eliminating the need for the reference voltage line and increasing the pixel area available for display.
Solution Approach 2:
The data voltage line is made multi-functional by using it to serve both as a data signal transmission line and as a reference voltage application line during the initialization period. This allows the same physical line to perform multiple functions, eliminating the need for a separate reference voltage line and enabling higher resolution pixel layouts.
2Reliability
If reference voltage line is included in pixel circuit, then internal compensation can be performed, but device complexity increases
Solution Approach 1:
The reference voltage line is extracted and removed from the circuit configuration. The patent demonstrates that the reference voltage function can be achieved without this separate line by utilizing the data voltage line during the initialization period, thereby simplifying the overall circuit configuration while maintaining compensation reliability.
Solution Approach 2:
The data voltage line is assigned multiple functions: it serves as both the data signal line during normal operation and as the reference voltage line during initialization. This multi-functionality reduces the total number of required circuit elements and simplifies the overall device complexity.
3Adaptability or versatility
If reference voltage line is removed, then pixel layout flexibility is improved, but initialization method must be changed
Solution Approach 1:
The patent employs periodic action by utilizing different time periods for different functions. During the initialization period, the data voltage line carries the reference voltage (black data voltage) to initialize the driving element. During the normal display period, the same line carries the data signal. This time-division multiplexing allows the removal of the reference voltage line while maintaining proper initialization functionality.
Solution Approach 2:
The reference voltage (black data voltage) is applied in advance during the initialization period before the actual display operation begins. This preliminary action ensures that the driving element is properly initialized using the data voltage line, enabling subsequent normal operation without requiring a separate reference voltage line.
Data Source
AI summary
A pixel circuit and a display device including the same are disclosed. The pixel circuit includes a driving element including a first electrode connected to a first power line, a gate electrode connected to a first node, and a second electrode connected to a second node, a first switch element connected between a data line through which a first or second data voltage is applied and the first node, and supplies the first data voltage to the first node responsive to a first gate signal, a second switch element connected between the data line and the second node and supplies the second data voltage to the second node responsive to a second gate signal, a light-emitting element including an anode connected to the second node and a cathode connected to a second power line, and a capacitor connected between the first and second nodes.