OLED Pixel Driving Method with Overlapping Scan and Emission Periods
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Solution Overview
Problem
Conventional OLED displays for stereoscopic images face issues with crosstalk and limited light emission periods, leading to luminance non-uniformity and increased power consumption, especially when displaying stereoscopic content.
Innovation Solution
The OLED display employs a novel driving method where the scan period and light emission period overlap, incorporating multiple transistors and capacitors to control the driving current independently of power source and threshold voltages, with a blank period inserted to prevent crosstalk and ensure sufficient light emission, while maintaining a simple power circuit structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the scan period and light emission period are separated sequentially as in conventional OLED displays, then the circuit structure can be simplified, but the light emission period becomes limited and luminance non-uniformity occurs
Solution Approach 1:
The patent implements overlapping scan period and light emission period within each frame period, creating a periodic driving pattern where data writing and light emission occur simultaneously in different time slots. This resolves the contradiction by allowing the light emission period to be extended without requiring sequential operation, thereby maintaining adequate emission duration while managing circuit complexity through structured periodic control
Solution Approach 2:
The patent applies preliminary action by pre-charging capacitors during the scan period before light emission begins. Specifically, the first capacitor stores data signal voltage and the second capacitor stores driving current voltage in advance, ensuring that when the light emission period starts, the necessary electrical conditions are already prepared. This allows the light emission period to be sufficiently long without extending the overall frame period excessively
2Manufacturing precision
If multiple transistors and capacitors are added to control driving current independently of power source and threshold voltages, then luminance non-uniformity is reduced, but device complexity increases
Solution Approach 1:
The patent changes the control parameters from direct power source voltage control to capacitor voltage storage control. By storing data signal voltage in the first capacitor and driving current voltage in the second capacitor, the system decouples the driving current from direct dependence on power source voltage and transistor threshold voltage variations. This parameter transformation achieves luminance uniformity while the complexity increase is offset by the systematic organization of additional components
Solution Approach 2:
The patent introduces capacitors as intermediary elements between the power source and the organic light emitting diode. The first capacitor C1 and second capacitor C2 act as voltage buffers that isolate the driving current from direct fluctuations in power source voltage and transistor threshold voltage. These intermediary capacitors absorb voltage variations and provide stable driving conditions, achieving luminance uniformity without requiring complex active compensation circuits
3Use of energy by moving object
If the aperture ratio is increased to reduce power consumption, then power efficiency improves, but control over driving current becomes more difficult
Solution Approach 1:
The patent replaces direct electrical control mechanisms with capacitor-based voltage storage mechanisms. Instead of relying on complex transistor switching networks to control driving current, the system uses the first capacitor C1 and second capacitor C2 to store and release voltage, thereby controlling the driving current through passive electrical elements. This substitution simplifies the control mechanism while accommodating larger aperture ratios that reduce power consumption
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 prevents pixel deterioration, ensures accurate luminance display, and reduces power consumption by maintaining a high aperture ratio and minimizing luminance non-uniformity due to voltage deviations.
Implementation Method 1
each of the plurality of pixels simultaneously emits light based on a driving current corresponding to a second data signal, which is a data signal of a previous frame
Data Source
AI summary
An organic light emitting diode (“OLED) display comprises a plurality of pixels which receives a first data signal, which is a data signal of a frame, through a plurality of data lines connected thereto, and stores the first data signal during a frame period of the frame, where the pixels simultaneously emit light based on a driving current corresponding to a second data signal, which is a data signal of a previous frame, where the frame period includes a scan period, during which the first data signal is stored, and a light emission period, during which the light is emitted based on the second data signal, the scan period and the light emission period overlap each other in the frame period.