Display Device Data Signal Line Dual-Function Characteristic Detection
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Solution Overview
Problem
Existing display devices face challenges in simultaneously compensating for degradation of both drive transistors and organic EL elements while minimizing circuit size, as previous techniques either fail to detect characteristics of both simultaneously or result in significant increases in circuit size.
Innovation Solution
An active matrix-type display device with a pixel matrix and monitoring control lines, where a pixel circuit driving unit performs characteristic detection during a frame period, storing correction data for video signal correction, and using a data signal line for both luminance signal transfer and characteristic detection, without adding new signal lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate monitoring lines are added for detecting characteristics of drive transistors and organic EL elements, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent makes the data signal line serve dual functions: transferring luminance signals during normal display operation and detecting characteristics of drive transistors and organic EL elements during monitoring periods. This multi-functionality eliminates the need for separate monitoring lines, resolving the contradiction between measurement precision and device complexity
Solution Approach 2:
The patent combines the luminance signal transfer function and characteristic detection function into a single data signal line. By merging these functions, the patent achieves precise characteristic detection without adding separate monitoring infrastructure, thus avoiding increased device complexity
2Productivity
If characteristic detection is performed during frame period, then productivity is improved, but loss of time occurs due to sharing of AD conversion resources
Solution Approach 1:
The patent implements periodic characteristic detection during frame periods by alternating between luminance signal transfer and characteristic detection phases. This periodic action allows the system to perform compensation efficiently while managing time loss through structured time-multiplexed operation of shared AD conversion resources
3Device complexity
If data signal line is used for both luminance signal transfer and characteristic detection, then device complexity is reduced, but measurement precision deteriorates due to signal interference
Solution Approach 1:
The patent segments the operation into distinct time phases: luminance signal transfer phase and characteristic detection phase. By temporally separating these functions, the patent prevents signal interference while maintaining the benefit of using a single data signal line, thus resolving the contradiction between device complexity and measurement precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables compensation for degradation of both drive transistors and organic EL elements while maintaining a compact circuit size, ensuring sufficient S/N ratio and effective current measurement through shared AD conversion and sample and hold functions.
Implementation Method 1
an organic EL element whose luminance is controlled by a flowing current
Implementation Method 2
one capacitor Cst, and one organic EL element OLED. The transistor T1 is an input transistor, and the transistor T2 is a drive transistor
Data Source
AI summary
A display device that can compensate for degradation of circuit elements while suppressing an increase in circuit size is implemented.A data signal line (S(j)) is not only used as a signal line that transfers a signal for allowing an organic EL element (OLED) in each pixel circuit (11) to emit light at a desired luminance, but also used as a signal line for characteristic detection. In addition, a switch (334) is provided between the data signal line (S(j)) and an internal data line (Sin(j)). In such a configuration, during an AD conversion period during which analog data obtained for characteristic detection is converted into digital data, the switch (334) is brought into an off state and a potential of the data signal line (S(j)) obtained immediately before the AD conversion period is supplied from through a predetermined control line (CL) to the data signal line (S(j)).