Display Pixel PWM for Inorganic LED Wavelength Stability
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Solution Overview
Problem
Inorganic light emitting diodes experience image quality deterioration due to variations in emitted light wavelength with changes in driving current, similar to organic light emitting diodes.
Innovation Solution
A display device design that includes specific pixel drivers and transistors to control the application period of driving current, maintaining a constant current level and adjusting the luminance of inorganic light emitting diodes, thereby stabilizing the wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the driving current applied to the inorganic light emitting diode is adjusted to control luminance, then the luminance can be varied, but the wavelength of emitted light changes causing image quality deterioration
Solution Approach 1:
The patent applies periodic action by using pulse width modulation (PWM) to control the light emitting element. Instead of varying the driving current continuously, the current is applied in periodic pulses with varying duty cycles. This allows luminance control through pulse duration while maintaining a constant current level during each pulse, thereby preventing wavelength shifts and image quality deterioration.
Solution Approach 2:
The patent changes the control parameter from driving current magnitude to pulse width (duty cycle). By maintaining the driving current at a fixed optimal level and varying only the duration of current application, the system achieves luminance control without the harmful side effect of wavelength variation that occurs when current magnitude is changed.
2Reliability
If the driving current level is maintained constant to stabilize wavelength, then image quality is preserved, but the ability to adjust luminance is limited
Solution Approach 1:
The patent resolves this contradiction by using periodic pulse signals with variable duty cycles. The driving current remains constant at an optimal level during each pulse, ensuring stable wavelength and image quality. Meanwhile, the luminance is adjusted by changing the proportion of time the current is applied (duty cycle), thus maintaining both image quality and luminance adjustability.
Solution Approach 2:
The patent introduces dynamic control through variable pulse width modulation. While the current amplitude remains fixed, the temporal characteristics of the driving signal are made dynamic by adjusting pulse duration. This allows the system to adapt luminance output without compromising the stability conditions required for consistent wavelength emission.
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 approach reduces or prevents image quality deterioration by stabilizing the wavelength of light emitted from inorganic light emitting diodes, ensuring consistent image quality.
Implementation Method 1
a light emitting element, a first pixel driver configured to generate a control current according to the first data voltage of the first data line, a second pixel driver configured to generate a driving current applied to the light emitting element
Data Source
AI summary
A display device includes a first scan line to receive a first scan signal, a second scan line to receive a second scan signal, a sweep signal line to receive a sweep signal, a first data line to receive a first data voltage, a second data line to receive a second data voltage, and a sub-pixel connected to the first scan line, the second scan line, the sweep signal line, the first data line, and the second data line. The sub-pixel includes a light emitting element, a first pixel driver configured to generate a control current according to the first data voltage of the first data line, and a second pixel driver configured to generate a driving current applied to the light emitting element according to the second data voltage of the second data line.