OLED Pixel Circuit Reducing Area and Color Break-Up
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Solution Overview
Problem
Existing organic light emitting display devices face challenges in reducing the area of pixel circuits while minimizing color break-up (CBU) due to the sequential emission of red, green, and blue light in a single frame period, which increases the pixel circuit area and leads to CBU.
Innovation Solution
The proposed solution involves a pixel circuit design where two driving transistors share a storage capacitor and are powered from different power source supply lines, reducing the number of transistors and allowing each organic light emitting diode to emit light at different times, with the sum of the colors of the emitted lights complementing each other to reduce CBU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple driving transistors are used to drive different colored OLEDs simultaneously, then color reproduction is improved, but pixel circuit area increases
Solution Approach 1:
The patent merges the driving functions of multiple transistors by having transistors share common power source supply lines. Specifically, first and second driving transistors share a common power source supply line, allowing them to be driven with the same power supply voltage. This sharing mechanism reduces the total number of transistors required while maintaining the ability to drive different colored OLEDs, thereby reducing pixel circuit area without sacrificing color reproduction capability.
Solution Approach 2:
The patent implements multi-functionality by designing driving transistors that can operate with different power source supply lines. The first driving transistor can be driven by a first power source supply line while the second driving transistor is driven by a second power source supply line, allowing the same transistor structure to serve multiple color driving functions. This universal design reduces the need for separate dedicated transistors for each color, thus reducing overall pixel circuit area.
2Area of stationary object
If sequential emission of red, green, and blue light is implemented in a single frame period, then pixel circuit area is reduced, but color break-up occurs
Solution Approach 1:
The patent employs periodic action by sequentially emitting different colored lights (red, green, and blue) in a single frame period. The first organic light emitting diode emits first light (e.g., red) while the second organic light emitting diode emits second light (e.g., green) at different times within the same frame. This time-division multiplexing approach allows the pixel circuit to use fewer transistors while maintaining color accuracy by preventing simultaneous emission that would cause color break-up.
Solution Approach 2:
The patent applies preliminary action by pre-configuring the driving transistors and power source supply lines before the emission sequence begins. The first driving transistor and second driving transistor are prepared with appropriate power source connections in advance, allowing the sequential emission of different colored lights to occur smoothly without color break-up. The storage capacitor is also pre-charged to sustain the voltage levels needed for sequential light emission.
3Device complexity
If transistors share power source supply lines, then device complexity is reduced, but power supply control becomes more challenging
Solution Approach 1:
The patent utilizes parameter changes by dynamically adjusting the power source supply lines based on the emission timing of different colored OLEDs. The first power source supply line and second power source supply line are selectively activated according to which OLED needs to emit light at a given time. This parameter-based control approach simplifies the transistor configuration while maintaining precise power supply control through timing-based voltage selection.
Solution Approach 2:
The patent implements feedback mechanisms through the storage capacitor that sustains voltage levels and the control circuitry that monitors the emission state of different colored OLEDs. The storage capacitor provides feedback by maintaining the voltage level needed for the next emission cycle, while the control system uses feedback signals to determine which power source supply line should be activated, ensuring proper power supply control despite the shared configuration.
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 design effectively reduces the pixel circuit area and minimizes color break-up by ensuring that the emission periods of different light colors do not overlap, enhancing the display's resolution and reducing CBU.
Implementation Method 1
a first organic light emitting diode OLED1(1,1) and a second organic light emitting diode OLED2(1,1)
Data Source
AI summary
A pixel set may include the following elements: a first diode for emitting first light of first color in a first time period; a second diode for emitting second light of second color in a second time period not overlapping the first time period; a first driving transistor for controlling electrical connection between a first power supply line and the first diode; a second driving transistor for controlling electrical connection between a second power supply line and the second diode; and a data transistor for transmitting a data voltage to a gate electrode of the first driving transistor and a gate electrode of the second driving transistor in response to a scan signal.