OLED Pixel Circuit Layout With Four Transistors for High Definition
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Solution Overview
Problem
Existing display devices using OLEDs face challenges in miniaturization and high definition due to the requirement of multiple transistors per pixel circuit, which increases the complexity and area required, hindering further reduction in size and improvement in display quality.
Innovation Solution
A display device configuration that includes a pixel circuit with a reduced number of transistors, specifically a first transistor, a second transistor, a third transistor, and a fourth transistor, where the first transistor supplies current to a display element via the fourth transistor, and the second and third transistors control the flow based on scanning and data lines, allowing for compact design and improved display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If five transistors are provided in one pixel circuit to compensate threshold and control current, then display quality is maintained, but pixel circuit area increases and miniaturization is hindered
Solution Approach 1:
The invention extracts and removes one transistor from the conventional five-transistor pixel circuit, resulting in a four-transistor configuration. This is achieved by reconfiguring the circuit so that the display element is connected between the drain of the first transistor and the data line, eliminating the need for one transistor while maintaining current control functionality and threshold compensation capabilities.
2Measurement precision
If five transistors are used per pixel circuit for current control, then current accuracy is improved, but device complexity increases
Solution Approach 1:
The invention removes one transistor from the pixel circuit while reconfiguring the remaining four transistors to maintain current control accuracy. The display element is connected between the drain of the first transistor and the data line, allowing the first transistor to control current flow directly to the display element without requiring an additional transistor for signal routing.
Solution Approach 2:
The four-transistor configuration performs multiple functions: the first transistor controls current to the display element, the second transistor handles scanning line signals, the third transistor manages data line signals, and the fourth transistor provides threshold compensation. This multi-functional design maintains current control accuracy while reducing overall circuit complexity.
3Reliability
If five transistors are provided in each pixel circuit, then threshold compensation is achieved, but manufacturing yield decreases due to increased complexity
Solution Approach 1:
The invention removes one transistor from the pixel circuit, reducing the component count from five to four transistors per pixel. This reduction simplifies the manufacturing process, increases yield by reducing the number of potential failure points, and maintains threshold compensation functionality through the reconfigured four-transistor circuit.
Data Source
AI summary
The display device includes a pixel circuit provided corresponding to a data line and a scanning line, the pixel circuit includes first to fourth transistors and a display element, and the first transistor supplies a current in accordance with a voltage between a gate node and a source node to the display element via the fourth transistor, the second transistor is disposed between the data line and the gate node of the first transistor and is turned on and off in accordance with a potential of the scanning line, the third transistor is disposed between the data line and a drain node of the first transistor, and the fourth transistor is disposed between the drain node of the first transistor and the display element.