OLED Driving Circuit with Inverse-Phase Scanning Signals
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Solution Overview
Problem
Organic light-emitting diode (OLED) display devices face issues with non-uniform brightness due to voltage drops and threshold voltage deviations in thin film transistors, leading to vertical strip phenomena and inconsistent gray scale display.
Innovation Solution
The implementation of a driving method that uses a driving voltage source, reference voltage and current sources, and a storage capacitor, along with specific switch elements and scanning signals to minimize voltage drops and threshold voltage effects, ensuring uniform brightness across the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional driving circuit with single-phase scanning signals is used, then the circuit structure is simple, but voltage drops and threshold voltage deviations cause non-uniform brightness and vertical strip phenomena
Solution Approach 1:
The scanning signal is divided into two inverse-phase signals (first scanning signal and second scanning signal) that are applied alternately to different sets of pixels. This segmentation allows the circuit to compensate for voltage drops and threshold voltage deviations by switching between two complementary driving paths, thereby achieving uniform brightness across the display without requiring complex additional compensation circuits.
Solution Approach 2:
Different regions of the display are driven by different scanning signals (first or second) depending on their position. Pixels in different areas receive appropriately timed signals that account for local voltage drops and threshold variations, ensuring each region displays uniform brightness according to its specific electrical characteristics.
2Stability of the object's composition
If inverse-phase scanning signals are used to compensate voltage drops, then brightness uniformity is improved, but the scanning circuit becomes more complex
Solution Approach 1:
The compensation function is merged into the existing scanning circuit by generating inverse-phase signals from a single scanning source. The first and second scanning signals are complementary versions of the same base signal, allowing the circuit to achieve compensation without adding independent complex control circuits, thus balancing brightness uniformity with circuit simplicity.
3Manufacturing precision
If multiple switch elements and storage capacitors are added to minimize voltage drops, then display uniformity is improved, but the number of components per pixel increases
Solution Approach 1:
The circuit uses periodic switching between the first and second scanning signals at specific phases. By alternating the application of inverse-phase signals in a periodic manner synchronized with the frame rate, the circuit achieves gray scale consistency and compensates for component variations without requiring additional permanent components in each pixel, thus maintaining manufacturing precision while limiting component count.
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
This approach effectively minimizes voltage drops and threshold voltage impacts, resulting in uniform display brightness and improved image quality by adjusting current paths and voltage supply phases.
Implementation Method 1
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Data Source
AI summary
An organic light-emitting diode display device and driving method thereof are provided. The organic light-emitting diode display device including a driving voltage source; a reference voltage source that generates a reference voltage; a reference current source; and a storage capacitor connected between a first node and a second node. An organic light-emitting diode device is connected between a third node and a ground voltage source. A first scanning signal is supplied to a first scan line. A second scanning signal is supplied to a second scan line, the second scanning signal having an inverse-phase against the first scanning signal.