OLED Pixel Circuit Current Splitting for Gray Scale Control
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Solution Overview
Problem
The challenge in OLED display technology is the difficulty in providing a small voltage value accurately for high current efficiency, which is required for achieving 256 gray scale display, as the current needed for the same brightness decreases, making it hard for the drive IC to supply the necessary voltage.
Innovation Solution
A pixel circuit design that includes a drive transistor, a drive control module, and multiple split light emitting control modules, which split the driving total current signal into smaller currents for each light emitting device, allowing for adjustment of gray scale display without changing the voltage adjustment range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the current efficiency of OLED is increased, then the current required for the same brightness becomes smaller, but the voltage range required for gray scale display becomes too small for the drive IC to provide accurate voltage values
Solution Approach 1:
The patent divides the single light emitting device into multiple light emitting devices (e.g., two OLEDs) that share the driving current. The drive transistor outputs a total current that is then distributed to multiple OLEDs, effectively segmenting the current path. This allows the drive IC to operate with a larger voltage range while achieving the same brightness with reduced individual current demands, thus resolving the voltage control precision issue.
2Use of energy by moving object
If the drive transistor supplies smaller current for high efficiency OLED, then energy consumption is reduced, but the voltage adjustment range becomes insufficient for accurate gray scale control
Solution Approach 1:
The patent merges multiple light emitting devices into a single pixel circuit structure, where they share common control transistors and capacitors. This merging allows the circuit to maintain low power consumption characteristics while expanding the effective voltage control range through current distribution, enabling both energy efficiency and operational ease.
3Device complexity
If a single light emitting device is used, then the circuit structure is simple, but the drive IC cannot accurately provide small voltage values required for high current efficiency display
Solution Approach 1:
The patent transitions from controlling brightness through a single current path to multiple parallel current paths. By adding the dimension of current distribution across multiple OLEDs, the system achieves finer control resolution without significantly increasing overall circuit complexity, as the additional components are integrated into the existing pixel structure.
Data Source
AI summary
A pixel circuit, an organic electroluminescent display panel and a display device. The pixel circuit comprises: a drive transistor, a drive control module, at least two split light emitting control modules and light emitting devices connected with output terminals of the split light emitting control modules in one-to-one correspondence respectively. Since the plurality of split light emitting control modules can split the driving total current signal outputted by the drive transistor based on the corresponding split control signal, the driving split current signal outputted to the corresponding light emitting device can be less than the driving total current signal. Thus, the driving current of the light emitting device under the same brightness can be reduced, thereby being capable of realizing adjustment of various gray scale display of the high current efficiency light emitting device.