OLED Luminance Compensation via Dynamic Voltage Control
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Solution Overview
Problem
Organic light emitting diode (OLED) displays face issues with maintaining desired luminance over time due to increased internal resistance and degradation, leading to reduced luminance despite the same electric current being used.
Innovation Solution
A display and driving method that includes a compensating unit to control the voltage of the first power source, using a resistor, amplifier, comparator, counter, and controller to adjust the voltage based on the electric current applied to the pixels, and a temperature sensor to adjust control values stored in a look-up table, ensuring the OLEDs receive a desired electric current and maintain luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the same electric current is used to drive OLEDs over time, then power consumption remains stable, but luminance decreases due to OLED degradation and increased internal resistance
Solution Approach 1:
The patent applies dynamics by making the drive current adjustable rather than fixed. The current driving the OLED is dynamically modified based on degradation characteristics, allowing the system to adapt to changing OLED properties over time while maintaining stable luminance output.
Solution Approach 2:
The patent implements feedback through a measurement unit that monitors OLED performance parameters and feeds this information back to a controller. The controller uses this feedback to adjust the drive current, creating a closed-loop system that compensates for degradation and maintains consistent luminance.
2Ease of manufacture
If OLEDs are driven with constant current, then manufacturing is simple, but luminance cannot be maintained as OLED degrades
Solution Approach 1:
The patent applies preliminary action by measuring and characterizing OLED degradation properties during or before normal operation. This preliminary data is stored and used to pre-calculate appropriate current adjustments, allowing the system to maintain luminance from the start without requiring complex real-time adaptation.
Solution Approach 2:
The patent changes the electrical parameters (drive current) based on measured OLED characteristics. By adjusting the current parameter according to the specific degradation state of each OLED, the system maintains reliable luminance while keeping the control mechanism relatively simple.
3Measurement precision
If complex compensation circuits with ADC and EEPROM are used, then luminance can be precisely maintained, but manufacturing cost increases
Solution Approach 1:
The patent extracts and measures only the essential degradation parameters of the OLED rather than implementing a complete complex measurement system. By focusing on the critical parameters needed for luminance compensation, the system achieves precise control without the full complexity and cost of traditional ADC/EEPROM-based systems.
Solution Approach 2:
The patent uses simpler, less expensive measurement and control components that may be replaced or recalibrated as needed, rather than investing in expensive, permanent ADC and EEPROM circuits. This approach maintains sufficient measurement precision for luminance control while significantly reducing manufacturing cost.
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 effectively maintains images of desired luminance regardless of OLED degradation by dynamically adjusting the voltage of the first power source, reducing manufacturing costs by not using an analog-to-digital converter and electrically erasable programmable read-only memory.
Implementation Method 1
The OLED displays may employ organic light emitting diodes that emit light by re-combination of electrons and holes
Implementation Method 2
an amplifier adapted to amplify a voltage across the resistor
Data Source
AI summary
An display and a driving method thereof are capable of displaying images of desired luminance. The display includes a scan driver connected to scan lines, a data driver connected to data lines, pixels connected to the scan lines and the data lines, the pixels being adapted to generate light while supplying an electric current from a first power source to a second power source, a power source unit for generating the first power source, and a compensating unit adapted to control a voltage value of the first power source.