OLED Data Driving Circuit Brightness Uniformity Compensation
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Solution Overview
Problem
Light emitting displays, particularly those using organic light emitting diodes (OLEDs), face challenges in achieving uniform brightness due to variations in transistor threshold voltage and electron mobility, which affect the consistency of images displayed.
Innovation Solution
A data driving circuit is developed that includes a decoder, latch, gamma voltage unit, digital-to-analog converter, current sink unit, voltage controller, and switching unit to generate and control data signals, compensating for variations in electron mobility and threshold voltages by using a compensation voltage generated based on the current sunk from the pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional data driving circuits are used without compensation mechanisms, then the device complexity is low, but the brightness uniformity deteriorates due to transistor parameter variations
Solution Approach 1:
The patent applies preliminary action by measuring and storing the compensation voltage in a capacitor during a first period before the actual data signal is applied in a second period. This pre-compensation approach allows the circuit to account for transistor parameter variations (threshold voltage and electron mobility) before they affect the displayed image, thereby improving brightness uniformity without requiring complex real-time adjustment mechanisms
Solution Approach 2:
The patent introduces a compensation voltage as an intermediary element that mediates between the data signal and the pixel output. This compensation voltage, generated based on measured transistor characteristics and stored in a capacitor, acts as a corrective intermediary that adjusts for parameter variations, enabling uniform brightness without directly modifying the transistor characteristics themselves
2Manufacturing precision
If compensation mechanisms are added to correct transistor variations, then the brightness uniformity is improved, but the device complexity increases
Solution Approach 1:
The patent applies preliminary action by measuring and storing the compensation voltage in a capacitor during a first period before the actual data signal is applied in a second period. This pre-compensation approach allows the circuit to account for transistor parameter variations (threshold voltage and electron mobility) before they affect the displayed image, thereby improving brightness uniformity without requiring complex real-time adjustment mechanisms
Solution Approach 2:
The patent introduces a compensation voltage as an intermediary element that mediates between the data signal and the pixel output. This compensation voltage, generated based on measured transistor characteristics and stored in a capacitor, acts as a corrective intermediary that adjusts for parameter variations, enabling uniform brightness without directly modifying the transistor characteristics themselves
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 enables the display of images with uniform brightness by compensating for variations in transistor characteristics, ensuring consistent light emission across all pixels regardless of electron mobility and threshold voltage differences.
Implementation Method 1
Light emitting displays may display images using organic light emitting diodes (OLEDs) that generate light when electrons and holes re-combine
Data Source
AI summary
A data driving circuit for driving pixels of a display to display images with uniform brightness may include a gamma voltage unit that generates gray scale voltages, a digital-analog converter that selects, as a data signal, one of the gray scale voltages using first data, a decoder that generates second data using the first data, a latch for storing the first data and the second data, a current sink that receives a predetermined current from the pixel during a first partial period of a complete period for driving the pixel based on the selected gray scale voltage, a voltage controller that controls a voltage value of the data signal using the second data and a compensation voltage generated based on the predetermined current, and a switching unit that supplies the data signal to the pixel during any partial period of the complete period elapsing after the first partial period.