OLED Pixel Circuit Compensation for Voltage Drop and Degradation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Digital driving methods for OLED displays are sensitive to variances in OLED characteristics and small voltage drops, and they face challenges in compensating for degradation and voltage drops, especially in large panels with high resolution.
Innovation Solution
A pixel circuit design that includes a driving unit, a read-out unit, and a compensation unit, where the compensation unit provides a compensation current based on the anode current detected by the read-out unit, using p-channel metal oxide semiconductor transistors and capacitors to maintain or adjust the compensation data, thereby compensating for decreased anode current due to OLED deterioration and voltage drops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If digital driving method is used for OLED display, then power consumption is reduced and response speed is improved, but the display becomes sensitive to OLED characteristic variances and voltage drops, making compensation difficult
Solution Approach 1:
The patent applies preliminary action by measuring the anode current of the OLED and storing compensation data before the actual display operation. The compensation unit pre-calculates and stores the compensation values in a memory unit, so that when voltage drops or OLED deterioration occurs, the compensation can be applied immediately without real-time calculation delays. This preliminary measurement and storage approach resolves the contradiction by preparing compensation data in advance while maintaining the power-efficient digital driving method.
Solution Approach 2:
The patent implements feedback by continuously monitoring the anode current of the OLED and using this information to adjust the compensation current. The read-out unit measures the actual anode current, and this measured value feeds back to the compensation unit, which then adjusts the compensation data stored in memory. This closed-loop feedback mechanism allows the system to adapt to OLED characteristic variations and voltage drops while maintaining digital driving efficiency, thus resolving the sensitivity issue without sacrificing power savings.
2Reliability
If compensation for OLED deterioration and voltage drops is implemented, then image quality consistency is improved, but device complexity increases due to additional compensation circuits and control units
Solution Approach 1:
The patent applies universality by designing the compensation unit to perform multiple functions: it measures anode current, calculates compensation values, stores compensation data in memory, and outputs compensation current. The driving unit also serves dual purposes by controlling both the main OLED driving and the compensation current output. This multi-functional design reduces the need for separate dedicated circuits for each compensation function, thereby improving image quality consistency while minimizing the increase in device complexity.
Solution Approach 2:
The patent merges the compensation function with the existing driving unit and control structure. Instead of adding a completely separate compensation system, the invention integrates the compensation unit into the existing pixel circuit architecture, sharing common elements such as the driving transistor and control signal lines. The compensation data is stored in a memory unit that is accessed by the existing control logic, merging storage and processing functions. This integration approach maintains image quality consistency while avoiding proportional increases in device complexity.
3Reliability
If compensation current is provided based on anode current measurement, then OLED performance degradation is compensated, but manufacturing precision requirements increase due to accurate current measurement and control needs
Solution Approach 1:
The patent applies parameter changes by converting the anode current measurement into a digital compensation value that can be stored and processed. Instead of requiring continuous high-precision analog current control, the system measures the anode current parameter, converts it to a digital compensation data value, and stores it in memory. This parameter transformation from continuous analog to discrete digital reduces the manufacturing precision requirements for current measurement circuits while maintaining effective compensation through digital-to-analog conversion in the compensation unit.
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 compensates for the decreased anode current caused by OLED degradation and voltage drops, ensuring consistent performance and image quality in OLED displays, particularly in large panels with high resolution.
Implementation Method 1
An OLED display generates an image using an OLED that emits light based on recombination of electrons and holes
Data Source
AI summary
A pixel circuit and organic light-emitting diode (OLED) display including the same are disclosed. In one aspect, a pixel circuit comprises an OLED electrically connected between a first node and a low power supply voltage, a driver electrically connected to the OLED at the first node and configured to drive the OLED with a voltage corresponding to a data signal based at least in part on a scan signal, a read-out unit configured to measure an anode current of the OLED based at least in part on a read control signal, and a compensation unit electrically connected to the OLED at the first node and configured to provide the OLED with a compensation current corresponding to a compensation data signal based at least in part on the measured anode current and a compensation control signal.