Organic EL Display Driving Method for Black Floating Prevention
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Solution Overview
Problem
In organic EL display devices, pause driving does not effectively reduce power consumption related to light emission, as the low-level power supply voltage during pause periods is not adequately reduced, leading to potential black floating issues due to insufficient voltage decrease during turn-off periods.
Innovation Solution
Implement a driving method that increases the low-level power supply voltage during pause periods and extends the initialization period for the anode terminal, ensuring the voltage remains at or below the light-emission threshold during black display, while reducing the voltage during normal driving periods to conserve power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the low-level power supply voltage is reduced during pause periods to save power, then power consumption is reduced, but the voltage may drop insufficiently during turn-off periods causing black floating
Solution Approach 1:
The patent applies dynamics by making the low-level power supply voltage variable rather than fixed. The voltage is dynamically adjusted based on the driving mode: during pause driving, a higher low-level voltage is applied to prevent black floating, while during normal driving, a lower low-level voltage is applied to reduce power consumption. This dynamic voltage adjustment resolves the contradiction between power saving and black floating prevention.
Solution Approach 2:
The patent changes the voltage parameter of the low-level power supply based on operating conditions. By switching between different voltage levels for the low-level power supply depending on whether the device is in pause mode or normal driving mode, the system optimizes both power consumption and display quality, preventing black floating while saving energy during pause periods.
2Reliability
If the low-level power supply voltage is increased during pause periods to prevent black floating, then black floating is prevented, but power consumption increases
Solution Approach 1:
The system dynamically adjusts the low-level power supply voltage based on the driving mode. During pause driving, a higher voltage is applied to prevent black floating, while during normal driving, the voltage is reduced to save power. This dynamic adjustment resolves the contradiction by applying higher voltage only when necessary for black floating prevention.
Solution Approach 2:
The patent implements parameter changes by varying the low-level power supply voltage level according to operating conditions. The voltage parameter is increased during pause periods to prevent black floating and decreased during normal driving to reduce power consumption, thus resolving the contradiction between reliability and energy usage.
3Use of energy by moving object
If pause driving is implemented to reduce power consumption, then overall power usage is reduced, but light emission power is not effectively reduced
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different power consumption components. While pause driving reduces the power consumption of driving circuits, the patent specifically addresses the light emission power component by adjusting the low-level power supply voltage to a higher level during pause periods, ensuring that organic EL elements do not emit light unintentionally (black floating), thus effectively managing energy loss in the light emission pathway.
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 reduces power consumption by maintaining the voltage at or below the light-emission threshold during pause periods, preventing black floating and lowering overall power usage in organic EL display devices.
Implementation Method 1
The organic EL element is also called an organic light-emitting diode (OLED), and is a self-emissive display element that emits light at luminance determined based on a current flowing therethrough
Data Source
AI summary
A display device is implemented that can reduce power consumption over a known example while preventing occurrence of black floating. The voltage value of a low-level power supply voltage ELVSS provided to a pixel circuit is set to a higher value in a pause driving period than in a normal driving period. Upon writing a data voltage, an anode initialization period for initializing an anode voltage of an organic EL element is provided. In this regard, an anode initialization period in the pause driving period is made longer than an anode initialization period in the normal driving period. To implement this, for example, a write frequency of a data voltage is made lower in the pause driving period than in the normal driving period.