OLED Pixel Circuit for High-Resolution Display Driving
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Solution Overview
Problem
As display panels increase in size and resolution, existing OLED display technologies face challenges in driving frequency and aperture ratio, particularly when displaying stereoscopic images, which require higher resolution and faster image data programming.
Innovation Solution
A pixel structure is developed with multiple transistors and capacitors that allow for simultaneous data programming and light emission, including a first capacitor connected between a data line and a node, switching and driving transistors, and reference voltage transistors, enabling efficient control of the organic light emitting diode (OLED) and ensuring a sufficient aperture ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the display panel size and resolution are increased, then the display quality is improved, but the driving frequency becomes insufficient and the aperture ratio decreases
Solution Approach 1:
The pixel circuit is divided into multiple functional blocks: a switching transistor for data programming, a light emitting transistor for controlling OLED current, and a driving transistor for current control. This segmentation allows each transistor to perform its function efficiently, enabling simultaneous data programming and light emission, thus maintaining high driving frequency even with increased panel size and resolution.
Solution Approach 2:
The first capacitor stores data voltage in advance during the scan period, and the reference voltage transistor pre-charges the first node with reference voltage. This preliminary action ensures that when the light emission period begins, all voltage conditions are already prepared, allowing immediate light emission without waiting for data programming to complete, thus maintaining high driving frequency.
2Measurement precision
If the display panel size and resolution are increased, then the display quality is improved, but the aperture ratio decreases
Solution Approach 1:
The first node serves multiple functions: it stores reference voltage when the reference voltage transistor is on, stores data voltage when the switching transistor is on, and provides the gate voltage for the light emitting transistor. This multi-functionality eliminates the need for separate dedicated nodes for each function, reducing the total circuit area and maintaining aperture ratio even with high resolution.
Solution Approach 2:
The patent merges the data storage function and reference voltage storage function into a single first capacitor and first node structure. By combining these functions, the circuit occupies less area compared to having separate storage structures, thus preserving aperture ratio while achieving high resolution.
3Measurement precision
If stereoscopic image display is implemented, then the image quality is improved, but the driving frequency requirement doubles
Solution Approach 1:
The patent enables continuous operation by allowing data programming and light emission to occur simultaneously in different pixels. During the scan period, while some pixels are being programmed with data, other pixels are already emitting light. This continuity ensures that even with doubled frame rates for stereoscopic display, the driving frequency requirement is met without compromising image quality.
4Loss of time
If multiple transistors and capacitors are added to enable simultaneous data programming and light emission, then the data programming time is sufficient, but the device complexity increases
Solution Approach 1:
The patent uses dynamic control of transistor states (on/off) based on timing signals. The switching transistor, reference voltage transistor, and light emitting transistor are dynamically switched during different periods (scan period and light emission period). This dynamic operation allows the same circuit components to serve multiple purposes at different times, reducing the need for additional static components and minimizing overall device complexity.
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 solution stabilizes the enlargement of display panels, improves high-resolution display capabilities, and enhances the quality of stereoscopic images by ensuring sufficient data programming time and aperture ratio, while reducing the influence of threshold voltage deviations.
Implementation Method 1
an organic light emitting material emitting light by the electric field
Data Source
AI summary
A display device includes a plurality of pixels including a first capacitor connected between a data line and a first node, a switching transistor connecting the first node and a second node, a first light emitting transistor transmitting a first power source voltage to the second node, a driving transistor having one electrode connected to the second node and controlling a driving current flowing to an organic light emitting diode (OLED), and a reference voltage transistor transmitting a reference voltage to the first node, wherein, when the first power source voltage is applied to the second node through the first light emitting transistor such that a light emitting step in which the OLED emits light is simultaneously performed in a plurality of pixels.