Capacitive Threshold Compensation for OLED Driving Transistors
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Solution Overview
Problem
Existing electronic devices that use transistors to drive elements like OLEDs face issues with variations in driving state due to errors in transistor threshold values, affecting grayscale levels and brightness.
Innovation Solution
The method involves using a transistor with capacitive elements to accurately compensate the threshold voltage and data voltage, allowing for precise control of the driving current and voltage by generating a sum voltage from these elements, which is then applied to the control terminal of the driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a transistor is used to drive a driven element, then the driving current can be controlled, but variations in transistor threshold values cause errors in driving state and grayscale levels
Solution Approach 1:
The patent implements a feedback mechanism where the threshold voltage of the driving transistor is detected and compensated through capacitive elements. The first capacitive element holds the threshold voltage, and the second capacitive element holds the data voltage, with their combined effect compensating for threshold variations to achieve accurate grayscale levels.
Solution Approach 2:
The patent changes the electrical parameters (voltages) stored in capacitive elements to compensate for threshold voltage variations. By adjusting the voltage levels in the first and second capacitive elements, the system compensates for transistor parameter variations and maintains accurate driving states.
2Manufacturing precision
If the gate of the driving transistor is set to have potential (Vdd−Vth) based on threshold voltage, then high definition and screen enlargement can be realized, but the time required to change the set potential increases
Solution Approach 1:
The patent performs preliminary action by pre-charging the first capacitive element with the threshold voltage before the actual driving operation. This allows the threshold compensation to be prepared in advance, reducing the time required during the actual potential change operation while maintaining high definition quality.
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 ensures accurate compensation of the threshold voltage and data voltage, leading to improved grayscale accuracy and reduced irregularities in brightness, enhancing the overall performance of the driven elements.
Implementation Method 1
a first capacitive element which holds a threshold voltage of the driving transistor in a compensation period
Implementation Method 2
a second capacitive element which holds a data voltage in a data writing period
Implementation Method 3
generates a sum voltage representing a sum of a voltage of the first capacitive element and a voltage of the second capacitive element
Data Source
AI summary
A method drives an electronic circuit for driving a driven element including a transistor which includes control, first, and second terminals, and in which a conduction state representing conduction between the first and second terminals changes depending on a potential of the control terminal, a first capacitive element that includes first and second electrodes, the first electrode being electrically connected to the control terminal, and a second capacitive element that includes third and fourth electrodes, the driven element being supplied with at least one of a driving voltage having a voltage level based on the conduction state in the transistor and a driving current having a current level based on the conduction state in the transistor. The method includes holding a threshold voltage of the transistor by the first capacitive element, with the second and third electrodes separated from each other, holding a data voltage by the second capacitive element, with the second and third electrodes separated from each other, and generating a sum voltage representing the sum of voltages of the first and second capacitive elements by electrically connecting the second and third electrodes, and supplying a potential based on the sum voltage to the control terminal of the transistor.