Pixel Driving Circuit for Micro LED Gray Scale Control
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Solution Overview
Problem
Micro light emitting diodes (LEDs) exhibit low light emitting efficiency at low current densities and struggle to display a wide range of gray scales effectively due to their characteristics of high efficiency at high current density and low efficiency at low current density.
Innovation Solution
A pixel driving circuit comprising a current control circuit and a gating circuit that controls the driving current and emission duration of micro LEDs to enable continuous or intermittent light emission, allowing for high gray scale display by adjusting the voltage signals and current flow, thereby achieving full gray scale representation at high current density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the driving current is increased to improve light emitting efficiency, then the light emitting efficiency improves, but the ability to display low gray scales deteriorates
Solution Approach 1:
The patent applies periodic action by controlling the micro LED to emit light intermittently rather than continuously. The gating circuit switches the light emitting element between on and off states within a frame period, creating pulsed light emission. This allows the average luminance to be reduced for low gray scales while maintaining high peak current density for high efficiency light emission during the on periods.
Solution Approach 2:
The patent implements dynamics by making the light emission state changeable between continuous and intermittent modes. The gating circuit dynamically adjusts the emission pattern based on the required gray scale level, transitioning from continuous emission for high gray scales to intermittent emission for low gray scales, thereby adapting the system behavior to different operating conditions.
2Adaptability or versatility
If the driving current is decreased to display low gray scales, then the gray scale range improves, but the light emitting efficiency deteriorates
Solution Approach 1:
The gating circuit implements periodic action by switching the micro LED on and off rapidly within a frame period. For low gray scales, the LED emits light at high current density during brief on-periods, then remains off during off-periods. This pulsed operation maintains high light emitting efficiency during emission while achieving low average luminance through duty cycle control.
3Illumination intensity
If the light emitting duration is extended to improve visibility, then the display brightness improves, but the power consumption increases
Solution Approach 1:
The patent applies periodic action by using intermittent light emission with controlled duty cycle. The gating circuit switches the micro LED between on and off states, allowing high brightness during on-periods while reducing average power consumption through the off-periods. The human eye integrates the pulsed light perception, maintaining visible brightness while reducing energy usage.
Solution Approach 2:
The patent maintains continuity of useful action by ensuring that within each frame period, the light emitting element is driven at optimal current density during on-periods to maintain high light emitting efficiency. The gating circuit ensures continuous control and adjustment of the emission pattern, keeping the system in an optimal operating state throughout the frame 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
The solution enables micro LEDs to display both high and low gray scales at high current density, enhancing light emitting efficiency and reducing power consumption while maintaining high gray scale representation.
Implementation Method 1
A micro light emitting diode has the characteristics of high light emitting efficiency at high current density, low light emitting efficiency and main wave peak shifting at low current density
Data Source
AI summary
The pixel driving circuit includes a current control circuit and a gating circuit. The current control circuit is configured to transmit a driving current signal to an element to be driven. The gating circuit is configured to transmit a second voltage signal from a second voltage signal terminal to the element to be driven such that the element to be driven continuously emits light or transmit a third voltage signal from a third voltage signal terminal to the element to be driven such that the element to be driven intermittently emits light, under the control of a scan signal from a scan signal terminal, a reset signal from a reset signal terminal and a second data signal from a second data signal terminal.