Pixel Circuit Periodic Reference Signal for Display Response
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Solution Overview
Problem
Existing display devices face challenges in achieving target brightness without causing motion blur or flickering, as they either require long response times for light-emitting elements when driven at normal currents or result in flickering when driven at lower illumination ratios.
Innovation Solution
A pixel circuit design that includes a switch, capacitor, driving transistor, and light-emitting diode (LED), where the reference signal is adjusted to provide different current magnitudes under the same data voltage, allowing for shorter response times and reduced flickering by varying the current output during different operation periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a normal driving current is provided to the light-emitting element to achieve target brightness, then the illumination ratio is maintained, but the response time becomes long causing motion blur
Solution Approach 1:
The patent applies periodic action by dividing the frame time into multiple sub-frames with different illumination ratios. A first sub-frame uses a higher illumination ratio to provide sufficient brightness, while a second sub-frame uses a lower illumination ratio. This periodic variation allows the light-emitting element to reach target brightness faster in the first sub-frame while maintaining perceptual brightness through the integration effect across multiple sub-frames, thereby reducing motion blur.
2Loss of time
If a large current is driven to the light-emitting element to shorten response time, then the reaction time is reduced, but the illumination ratio must be lowered to maintain target brightness which causes flickering
Solution Approach 1:
The patent uses periodic action to divide the frame time into multiple sub-frames with varying illumination ratios. By alternating between higher and lower illumination ratios across sub-frames, the system can use larger currents in the first sub-frame to achieve fast response without causing perceptible flickering, as the human eye integrates the brightness across the periodic sub-frames to perceive stable target brightness.
Solution Approach 2:
The patent segments the frame time into multiple sub-frames, each with different illumination ratios and current levels. This segmentation allows the driving current to be optimized for fast response in the first sub-frame while distributing the total light output across multiple segments, preventing the perception of flickering that would occur with continuous low-current operation.
3Speed
If the illumination ratio is lowered to maintain target brightness with large current, then the response time is shortened, but the human eye notices display flickering
Solution Approach 1:
The patent implements periodic action by creating multiple sub-frames with alternating illumination ratios within each frame time. The first sub-frame uses a higher illumination ratio with larger current for fast response, while the second sub-frame uses a lower illumination ratio. This periodic structure allows the display to achieve fast response speeds without causing perceptible flicker, as the human visual system integrates the alternating brightness levels into a perceived steady state.
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 enables a broader range of applications by shortening response times for high currents and maintaining uninterrupted illumination with reduced flickering, making it suitable for high-resolution devices like virtual reality displays.
Implementation Method 1
a first terminal of the capacitor and the first switch are coupled to a node, a second terminal of the capacitor is configured to receive a reference signal. the reference signal is changed to different voltages during different operation periods, the capacitor couples a voltage difference between the different voltages to the node according to the reference signal
Implementation Method 2
The LED is coupled to the driving transistor, the LED emits light according to the current
Data Source
AI summary
A pixel circuit is disclosed herein, which includes a first switch, a capacitor, a driving transistor, and a light-emitting diode (LED). The first switch outputs voltage data in response to a scan signal. A first terminal of the capacitor and the first switch are coupled to a node. A second terminal of the capacitor receives a reference signal. The driving transistor is coupled to the node, and configured to output current according to a voltage stored in the node. The LED is coupled to the driving transistor, and emits light according to the current. The reference voltage is different during different operation periods. The driving transistor outputs a first current according to the voltage data and the voltage difference, and outputs a second current according to the voltage data during different operation periods, such that the LED emits a first light and a second light during different operation periods.