Pixel Circuit for M-OLED Duty Cycle Extension
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Solution Overview
Problem
The existing surface batch light emission drive methods for micro-organic light emitting diode (M-OLED) panels in augmented reality glasses result in a short light emission period, leading to decreased luminance and visual recognition issues due to a low light emission duty cycle.
Innovation Solution
A pixel circuit comprising a first transistor to control current to a light emitting element, a first capacitor to hold voltage, a second transistor to sample signal voltage, a second capacitor to hold the sampled voltage, and a third transistor to connect the second capacitor with the first capacitor, allowing for efficient voltage transfer and extended light emission periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If surface batch light emission drive is used to cause all pixels to simultaneously emit light, then superimposition of real world and display video is enhanced, but light emission period becomes very short resulting in low luminance and flicker
Solution Approach 1:
The pixel circuit performs preliminary actions by sampling the video signal voltage in advance using the second transistor and storing it in the second capacitor. The circuit also performs threshold correction in advance using the fourth transistor and fifth capacitor before the light emission period begins. This allows the light emission period to be extended without compromising display quality, as the necessary signal processing is completed beforehand.
Solution Approach 2:
The pixel circuit is divided into multiple functional segments: a first transistor for current control, a second transistor for signal sampling, a third transistor for capacitor connection, a fourth transistor for threshold correction, and multiple capacitors for voltage holding. This segmentation allows each component to perform its function efficiently, enabling extended light emission duration while maintaining luminance quality.
2Duration of action of moving object
If light emission period is extended to increase duty cycle, then luminance and flicker issues are improved, but signal writing and threshold correction time may be insufficient
Solution Approach 1:
The circuit performs signal sampling and threshold correction as preliminary actions before the light emission period. The second transistor samples the video signal voltage and stores it in the second capacitor. The fourth transistor performs threshold correction using the fifth capacitor. These preliminary actions ensure that when the light emission period begins, all necessary signal processing is already complete, allowing the light emission period to be extended without compromising the time available for signal writing and threshold correction.
3Duration of action of moving object
If multiple transistors and capacitors are added to extend light emission period, then light emission duty cycle increases, but device complexity increases
Solution Approach 1:
The pixel circuit components serve multiple functions: the second capacitor both holds the sampled video signal voltage and facilitates voltage transfer to the first capacitor. The third transistor both connects the capacitors and enables charge transfer. The fourth transistor performs threshold correction while also controlling the timing of operations. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity while still achieving extended light emission period.
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 configuration increases the light emission duty cycle, enhancing luminance and reducing flicker issues by allowing longer light emission periods while maintaining efficient operation.
Implementation Method 1
a first capacitor configured to hold the voltage supplied to the first terminal
Implementation Method 2
a second capacitor configured to hold the signal voltage sampled by the second transistor
Implementation Method 3
a third transistor configured to connect the second capacitor and the first capacitor and set a voltage corresponding to the signal voltage to the first capacitor by transferring electric charges accumulated in the second capacitor to the first capacitor
Data Source
AI summary
Provided are a pixel circuit, a display device, and a driving method that suppress a decrease in luminance. A pixel circuit according to the present disclosure includes a first transistor configured to control a current supplied to a light emitting element according to a voltage supplied to a first terminal, a first capacitor configured to hold the voltage supplied to the first terminal, a second transistor configured to sample a signal voltage of a video signal line, a second capacitor configured to hold the signal voltage sampled by the second transistor, and a third transistor configured to connect the second capacitor and the first capacitor and set a voltage corresponding to the signal voltage to the first capacitor by transferring electric charges accumulated in the second capacitor to the first capacitor.