Pixel Circuit Separating Data Writing and Vth Compensation
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Solution Overview
Problem
Existing pixel circuits in display technologies face challenges in reliably compensating the threshold voltage (Vth) within a short time, especially at high frame rates, due to the simultaneous nature of data writing and Vth compensation, which affects display quality.
Innovation Solution
A pixel circuit is designed with separate data writing and Vth compensation circuits, allowing for independent control of data writing and potential adjustments through a coupling effect, enabling flexible adjustment of the gate potential of the driving transistor and reliable resetting of the driving transistor at low frame rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If data writing and Vth compensation are performed simultaneously in existing pixel circuits, then the circuit structure can be simplified, but the compensation accuracy deteriorates especially at high frame rates
Solution Approach 1:
The pixel circuit is divided into separate data writing circuit and Vth compensation circuit, allowing independent operation of each function. The data writing circuit writes data to the first node while the Vth compensation circuit separately compensates the threshold voltage of the driving transistor, eliminating interference between the two processes and ensuring accurate compensation even at high frame rates.
Solution Approach 2:
The Vth compensation is performed in advance during a dedicated compensation phase before the data writing phase. By completing the threshold voltage compensation beforehand, the circuit ensures that the driving transistor has accurate Vth values ready for subsequent data writing and display operations, preventing compensation errors that would occur with simultaneous operation.
2Productivity
If data writing and Vth compensation are performed simultaneously, then the operating speed can be maintained, but the display quality deteriorates
Solution Approach 1:
The pixel circuit operates in periodic phases: a compensation phase where Vth is adjusted, followed by a data writing phase, then a display phase. This periodic separation ensures that compensation is always performed under optimal conditions before data writing, maintaining both high operating speed and excellent display quality through rhythmic alternation of functions.
3Device complexity
If the gate potential of the driving transistor is not adjusted flexibly, then the circuit operation is simple, but the display performance becomes unstable at low frame rates
Solution Approach 1:
The gate potential of the driving transistor is made dynamically adjustable through the Vth compensation circuit that can modify the potential at the first node based on detected threshold voltage variations. This dynamic adjustment capability ensures stable display performance at low frame rates by adapting the gate potential to actual circuit conditions, while the overall circuit structure remains relatively simple.
Data Source
AI summary
Provided is a pixel circuit. In the pixel circuit, a data writing circuit controls the connection or disconnection between a data terminal and a first node, a reset circuit controls the connection or disconnection between an initial power supply terminal and a second node and between an initial power supply terminal and a light-emitting element, and controls the connection or disconnection between a reference power supply terminal and the first node, a potential adjustment circuit adjusts the potentials of the first node, the second node and the third node, a light emission control circuit controls the connection or disconnection between the reference power supply terminal and the first node, and controls the connection or disconnection between the fourth node and the light-emitting element, and a drive circuit drives the light-emitting element to emit light.