OLED Driver Using Periodic Pulses to Reduce Heat
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Solution Overview
Problem
Organic light-emitting diodes (OLEDs) suffer from low lifetime and efficiency due to excessive electron flow and heat generation during radiant emittance, especially at high brightness, leading to rapid degradation and low wall plug efficiency.
Innovation Solution
An OLED driver system that generates bias and injection pulses based on transition and relaxation times of the OLED, adjusting voltage and current to optimize light emission, including a combiner to produce a combined output, and a system controller to manage dwell time, pulse repetition rate, and pulse current to achieve target emittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If continuous current is applied to OLED at high brightness, then light emission intensity increases, but electron waste and heat generation increase leading to low efficiency and short lifetime
Solution Approach 1:
The patent applies periodic pulsed current instead of continuous current to drive the OLED. The current is delivered in short pulses with duration shorter than the OLED relaxation time, creating periodic excitation that maintains light emission while allowing the material to relax between pulses. This reduces cumulative electron waste and heat generation while maintaining high brightness during the pulse periods.
Solution Approach 2:
The patent dynamically adjusts the pulse parameters (duration, repetition rate, amplitude) based on the OLED's relaxation time characteristics. By making the pulse duration variable and shorter than the relaxation time, the system adapts to the material's transient response, optimizing efficiency across different brightness levels while preventing excessive heat accumulation.
2Illumination intensity
If high current is applied to OLED, then light emission increases, but wall plug efficiency drops below 20%
Solution Approach 1:
By using periodic pulsed current with pulse width shorter than the OLED relaxation time, the patent ensures that current is applied only during the productive emission phase. The OLED converts electrical energy to light during the pulse, then relaxes without current flow, preventing wasteful continuous heating. This timing optimization improves wall plug efficiency by delivering current only when it produces light rather than heat.
Solution Approach 2:
The patent changes the temporal parameters of current delivery from continuous to pulsed mode, with pulse duration and repetition rate optimized based on the OLED's relaxation time. This parameter transformation allows the same average light output to be achieved with lower peak currents and reduced overall energy waste, improving wall plug efficiency.
3Illumination intensity
If current flows continuously through OLED, then light emission is maintained, but temperature degradation occurs due to heating
Solution Approach 1:
The patent uses periodic pulsed current with intervals between pulses longer than the thermal relaxation time of the OLED material. During the pulse, light emission occurs and some heating happens. During the interval, the OLED cools down before the next pulse. This periodic on-off cycling maintains average light emission while preventing temperature accumulation and thermal degradation.
Solution Approach 2:
The patent allows the OLED to complete its relaxation process before applying the next current pulse. By waiting for the transient state to decay and temperature to partially dissipate, the system prepares the material for the next efficient emission cycle, preventing cumulative thermal damage while maintaining light output.
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
The solution reduces electron waste and heat deposition in the polymer layer, enhancing OLED efficiency and extending its service life by using short, intense pulses that maintain luminance with lower average power consumption and reduced thermal effects.
Implementation Method 1
An organic light-emitting diode (OLED) has an emissive electroluminescent layer formed from a film of organic compound that emits light in response to an electric current
Implementation Method 2
OLED driver, OLED apparatus equipped with the driver and method of the apparatus... based on Meta-stability of transient states
Data Source
AI summary
An organic light emitting diode (OELD) driver for driving at least one OELD having a transition time. The OLED driver has a power supply coupled to a bias pulse controller and an injection pulse controller. The bias pulse controller is configured to generate a bias pulse output based on the OLED transition time. The injection pulse controller is configured to generate an injection pulse output. A combiner is coupled to the bias pulse output and the injection pulse output. The combiner is configured to generate a combined output to drive the OLED. A system controller may be coupled to at least one of the power supply, bias pulse controller and injection pulse controller to adjust the voltage/current delivered to the OLED to adjust a light level output of the OLED. The OLED driver may include a switch that changes a dwell time of the bias pulse controller output.