Polarity Switching Circuit for Organic EL Display
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Solution Overview
Problem
Conventional organic electroluminescent display devices require separate configurations for negative and positive polarity video signals, limiting their versatility and ability to display accurate inverted images for both polarities.
Innovation Solution
A polarity switching circuit that inverts or maintains the polarity of digital video signals, along with D/A converters, allows the display device to convert digital signals to analog and drive self-emissive elements for both negative and positive polarity video signals, enabling the display of accurate inverted images by switching the white and black levels accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate display devices are provided for negative and positive polarity video signals, then each device can display accurate images for its specific polarity, but the device versatility and adaptability are reduced
Solution Approach 1:
The display device is designed to handle both negative and positive polarity video signals through a unified architecture. The video signal processing circuit includes polarity detection functionality that automatically identifies the input signal polarity and switches the driving transistor configuration accordingly, enabling a single device to serve multiple polarity requirements without sacrificing image accuracy
2Adaptability or versatility
If a single display device is used for both negative and positive polarity video signals, then device versatility is improved, but the complexity of the video signal processing circuit increases
Solution Approach 1:
The video signal processing circuit employs dynamic switching between different driving transistor configurations based on the detected polarity of the input video signal. The circuit automatically reconfigures the connection between the video signal, driving transistors, and organic EL elements, transitioning between P-channel and N-channel transistor arrangements as needed to maintain optimal performance for the current signal polarity
Solution Approach 2:
A polarity detection circuit and switching mechanism are introduced as intermediary components between the video signal input and the driving transistors. This intermediary layer automatically identifies the signal polarity and routes the signal through the appropriate transistor configuration, managing the complexity centrally rather than requiring separate dedicated circuits for each polarity type
3Device complexity
If the driving transistor configuration is fixed for one polarity, then the circuit design is simplified, but the ability to display accurate inverted images for the opposite polarity is lost
Solution Approach 1:
The driving transistor configuration is made dynamically switchable rather than fixed. The system detects the polarity of the input video signal and automatically switches between P-channel and N-channel transistor arrangements, ensuring that the correct transistor type is used for each polarity to maintain accurate image display including proper inversion characteristics
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
Enables the use of a single self-emission type display device for both negative and positive polarity video signals, ensuring accurate image inversion and expanded application flexibility.
Implementation Method 1
an organic electroluminescent element as a self-emissive element
Data Source
AI summary
The invention provides an organic EL display device usable for both negative and positive polarity video signals. The organic EL display device of the invention has a polarity switching circuit switching a polarity of a digital video signal. In a case where a display panel is made for a negative polarity video signal, when a negative digital video signal is inputted, this polarity switching circuit lets the negative polarity digital video signal pass therethrough without inverting its polarity. When a positive polarity digital video signal is inputted, this polarity switching circuit inverts a polarity of the positive polarity digital video signal and inverts and switches reference data for a white level and reference data for a black level in order to obtain an accurate inverted image. An output of the polarity switching circuit is converted into an analog video signal through a first D/A converter and outputted to the display panel.