PWM and PAM Pixel Drivers for Stable Inorganic LED Color
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Inorganic light emitting diode elements in display devices experience a change in wavelength due to variations in driving current, leading to deteriorated image quality when driven similarly to organic light emitting diode elements.
Innovation Solution
A display device design incorporating pulse width modulation (PWM) and pulse amplitude modulation (PAM) signals, with specific pulse configurations and pixel drivers to control the application period of driving current, maintaining a constant current while adjusting luminance by varying the emission period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If inorganic light emitting diode element is driven by adjusting driving current magnitude to control luminance, then luminance control is achieved, but wavelength of emitted light varies causing image quality deterioration
Solution Approach 1:
The patent applies periodic pulse signals (PWM and PAM) to drive the inorganic light emitting diode element instead of continuous current adjustment. By using periodic pulses with controlled duty cycles and amplitudes, the system achieves luminance control through temporal modulation rather than magnitude adjustment, thereby maintaining consistent wavelength throughout the emission period
Solution Approach 2:
The patent changes the control parameters from continuous current magnitude to discrete pulse characteristics (width, amplitude, duty cycle). By modifying pulse parameters rather than continuous current levels, the system achieves luminance variation while keeping the actual current magnitude during emission constant, thus preventing wavelength shift
2Illumination intensity
If driving current magnitude is adjusted to control luminance, then luminance varies, but color coordinates become inconsistent
Solution Approach 1:
The patent uses periodic pulse modulation techniques where luminance is controlled by varying pulse duration (PWM) or pulse amplitude (PAM) within a fixed frequency cycle. This periodic approach ensures that the light emitting element operates at consistent current levels during emission, maintaining stable color coordinates while achieving desired luminance variations through temporal control
Solution Approach 2:
The system transitions from controlling luminance via current magnitude to controlling via pulse temporal parameters (width, duty cycle, amplitude timing). This parameter transformation allows independent control of luminance and color characteristics, maintaining consistent color coordinates by keeping the emission current magnitude constant
3Ease of operation
If inorganic light emitting diode element is driven similarly to organic light emitting diode element, then drive simplicity is maintained, but image quality deteriorates due to wavelength change
Solution Approach 1:
The patent implements a universal pulse modulation interface that can drive inorganic light emitting diode elements with the same control architecture used for organic variants. By adopting PWM and PAM techniques, the system maintains drive simplicity and compatibility while specifically addressing the wavelength stability requirements of inorganic materials through standardized pulse control protocols
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 optimal luminous efficiency and maintaining consistent color coordinates.
Implementation Method 1
a light emitting element
Implementation Method 2
The light emitting element may include an inorganic light emitting diode element
Data Source
AI summary
A display device includes a scan write line, a PWM emission line, a PAM emission line, a sweep signal line, a first data line, a second data line, and a subpixel connected thereto, and including a light emitting element, a first pixel driver to supply a control current to a node according to the first data voltage in response to the PWM emission signal, a second pixel driver to generate a driving current according to the second data voltage in response to the PWM emission signal, and a third pixel driver to supply the driving current to the light emitting element according to the PAM emission signal and a voltage of the node, wherein the PWM emission signal includes a plurality of PWM pulses, the PAM emission signal includes a plurality of PAM pulses, and a number of the PWM pulses is greater than a number of the PAM pulses.