OLED Pixel Circuit Gray Scale Control via Transistor Potential Adjustment
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Solution Overview
Problem
Conventional OLED displays face challenges in accurately controlling gray scales due to limited differences in data voltages, leading to difficulties in spreading gray scales effectively.
Innovation Solution
A pixel circuit comprising transistors T1 to T7 and capacitor C1, with specific signal control phases and voltage applications, allows for precise control of the organic light-emitting diode's brightness by adjusting the potential of the control terminal of transistor T1, thereby increasing the difference between adjacent gray scale data voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional data voltage writing method is used, then the pixel circuit structure is simple, but the gray scale differentiation capability is insufficient
Solution Approach 1:
The pixel circuit is divided into multiple functional modules: initialization module (transistors T4, T7), data writing module (transistor T2), compensation module (transistor T3, capacitor C1), light emitting module (transistor T5, T6), and control module (transistor T1). Each module performs a specific function in the gray scale control process, enabling precise differentiation while maintaining modular simplicity.
Solution Approach 2:
The circuit performs preliminary initialization of the OLED anode and transistor T1 control terminal to reference voltage Vref before data writing. This preliminary action establishes a known baseline state, enabling accurate subsequent gray scale differentiation by compensating for threshold voltage variations and ensuring consistent starting conditions for each frame.
2Measurement precision
If data voltage is written directly to control terminal of T1, then the circuit operation is simple, but the gray scale control precision is limited
Solution Approach 1:
Capacitor C1 serves as an intermediary between the data writing path and the control terminal of transistor T1. It stores the compensating voltage generated during the data writing phase and releases it during the light emitting phase, enabling precise gray scale control by mediating the voltage transfer and isolation between different operational phases.
Solution Approach 2:
The circuit performs self-compensation for threshold voltage variations of transistor T1 through the compensation phase. By automatically generating and storing the compensating voltage in capacitor C1 during the data writing phase, the circuit eliminates the need for external calibration or adjustment, achieving precise gray scale control through self-service mechanisms.
Data Source
AI summary
The present disclosure relates to a pixel circuit, a driving method of a pixel circuit, and a display apparatus. The pixel circuit includes a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, a sixth transistor, a seventh transistor, a first capacitor and an organic light-emitting diode. A control terminal of the fourth transistor is configured to input a first scanning signal. A first electrode of the fourth transistor is connected to a second electrode of the third transistor, a control terminal of the first transistor and a terminal of the first capacitor. Another terminal of the first capacitor is connected to a second electrode of the second transistor, a second electrode of the fifth transistor and a first electrode of the first transistor.