OLED Response Time Accelerator TFT for Low Luminance Turn-Off
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Solution Overview
Problem
Existing organic light emitting diodes (OLEDs) face challenges in reducing turn-off time, which affects their response time and efficiency, especially at low luminance levels.
Innovation Solution
Incorporating a response time accelerator thin film transistor (TFT) in the drive circuit of OLEDs, which short or reverse biases the OLED for a predetermined period during a frame time, along with independently controllable emissive areas to manage light output and current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If conventional drive circuits are used without additional components, then device complexity is low, but turn-off time is long
Solution Approach 1:
The patent applies preliminary action by introducing a response time accelerator TFT that is pre-configured in the drive circuit to actively discharge accumulated charges during the turn-off period. This pre-prepared mechanism rapidly removes trapped charges before they can cause prolonged emission, thereby reducing turn-off time without requiring complex additional circuitry throughout the entire device.
2Speed
If standard emission control is used, then current density is uniform, but response time at low luminance is slow
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the electrical parameters of the response time accelerator TFT based on the operational state of the OLED. At low luminance levels, the accelerator TFT is activated to change the discharge rate of accumulated charges, thereby speeding up the response time specifically when needed most - during low luminance operation - without affecting normal high luminance performance.
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 significantly reduces the OLED's response time, especially at low luminance levels, by increasing current density and ensuring rapid discharge of charges, thereby improving display performance and efficiency.
Implementation Method 1
a response time accelerator thin film transistor (TFT) configured to short or reverse bias the OLED for a predetermined period of time during a frame time
Implementation Method 2
OLEDs make use of thin organic films that emit light when voltage is applied across the device
Data Source
AI summary
Embodiments of the disclosed subject matter provide a device that includes an organic light emitting device (OLED), and a drive circuit to control the operation of the OLED, comprising a response time accelerator thin film transistor (TFT) configured to short or reverse bias the OLED for a predetermined period of time during a frame time. Other embodiments include an OLED having a plurality of sub-pixels, where one or more of sub-pixels configured to emit light of at least a first color comprises a first emissive area and a second emissive area that are independently controllable, where the first emissive area is larger than the second emissive area. The controller is configured to control the second emissive area to have (i) a higher brightness, and/or (ii) a higher current density than the first emissive area for a first sub-pixel luminance level that is less than a maximum luminance.