Sub-Pixel PWM Driving for Stable Color Inorganic LED Displays
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Solution Overview
Problem
Existing display devices using inorganic light emitting diodes face image quality deterioration due to changes in the wavelength of emitted light with varying driving currents, which is not effectively addressed by existing technologies.
Innovation Solution
A display device is designed with a sub-pixel configuration that includes a light emitting element, a first pixel driver to generate a control current, a second pixel driver to maintain a constant driving current, and a third pixel driver to control the application period of the driving current, thereby adjusting the luminance without changing the driving current.
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 pulse width modulation (PWM) to control the light emitting element, where the driving current is applied in periodic pulses with varying duty cycles. The third pixel driver controls the period in which the driving current is applied to the light emitting element according to the control current, thereby adjusting luminance through pulse duration rather than current magnitude, which prevents wavelength shift and maintains image quality
Solution Approach 2:
The patent changes the control parameter from driving current magnitude to pulse width (duty cycle). By maintaining a constant driving current magnitude and varying only the pulse width, the system achieves luminance control without causing the wavelength shift that occurs when current magnitude is changed. This parameter transformation resolves the contradiction between luminance adjustment and image quality maintenance
2Use of energy by moving object
If the driving current magnitude is increased to improve luminous efficiency, then more light is emitted, but the wavelength changes causing color coordinate shifts
Solution Approach 1:
The patent uses periodic pulse signaling where the driving current is applied in controlled pulses. The luminous efficiency is maintained by optimizing the pulse characteristics (amplitude and width) rather than continuously increasing current magnitude. This periodic control allows the light emitting element to operate at optimal efficiency points while preventing wavelength drift through consistent current amplitude
Solution Approach 2:
The patent implements a feedback mechanism where the third pixel driver adjusts the pulse width based on control signals to maintain optimal operating conditions. By monitoring and adjusting the pulse parameters, the system maintains the driving current at an optimal magnitude for luminous efficiency while compensating for any conditions that might cause wavelength shift, thereby maintaining color consistency
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 allows for the reduction or prevention of image quality deterioration caused by changes in the wavelength of emitted light, while maintaining optimal luminous efficiency and consistent image color coordinates.
Implementation Method 1
a light emitting element... 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.