Pixel Driving Circuit for Micro LED Full Gray Scale Display
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Solution Overview
Problem
Micro light emitting diodes (Micro LEDs) have low light emitting efficiency at low current density, making it challenging to achieve full gray scale display effectively.
Innovation Solution
A pixel driving circuit comprising a current control sub-circuit and a gating sub-circuit that outputs a gray scale current signal and controls light emission intensity and duration, allowing for continuous or intermittent light emission to achieve high and low gray scale displays by adjusting the magnitude of the gray scale data signal and pulse voltage signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the driving current input into the micro light emitting diode is reduced to achieve low gray scale display, then the power consumption is reduced, but the light emitting efficiency decreases and main wave peak shifting occurs
Solution Approach 1:
The patent applies periodic action by using pulse width modulation (PWM) to control the micro LED. Instead of using low current density which causes efficiency loss, the circuit rapidly switches the LED on and off with high current density pulses. The duty cycle of these pulses is adjusted to achieve different gray levels, maintaining high light emitting efficiency while enabling low gray scale display and reducing average power consumption.
Solution Approach 2:
The patent implements dynamics by using a dual-gating mechanism with independent control of turn-on voltage and turn-off voltage. The first gate controls the turn-on timing and the second gate controls the turn-off timing, allowing dynamic adjustment of the pulse width. This dynamic control enables precise gray scale representation while maintaining the LED in high-efficiency operating regions through rapid switching.
2Reliability
If the driving current is increased to maintain high light emitting efficiency, then the light emitting efficiency is improved, but the power consumption increases
Solution Approach 1:
The patent uses periodic high-current pulses instead of continuous low-current operation. By switching the micro LED on and off rapidly with high current density during the on-period, the light emitting efficiency is maximized. The average power consumption is controlled by adjusting the duty cycle of these periodic pulses, allowing high efficiency operation with reduced overall power consumption.
Solution Approach 2:
The patent maintains continuous control over the LED operation through dual-gating mechanisms that ensure the LED is always in a controlled state—either actively emitting at high efficiency or safely off. The continuous adjustment of pulse width and timing allows the system to maintain optimal operating conditions while managing power consumption continuously throughout operation.
3Device complexity
If conventional driving circuits are used for micro light emitting diodes, then the circuit structure is simple, but full gray scale display cannot be achieved due to low light emitting efficiency at low current density
Solution Approach 1:
The patent segments the control function into two independent gates: a first gate for controlling turn-on and a second gate for controlling turn-off. This segmentation allows independent optimization of each control function, enabling precise pulse width modulation for full gray scale display. The segmentation transforms a single control signal into two coordinated control signals, achieving enhanced functionality while maintaining reasonable circuit complexity.
Solution Approach 2:
The patent introduces an intermediary dual-gating mechanism between the control circuit and the micro LED. This intermediary layer translates simple control signals into precise current pulses with adjustable width and timing. The gating circuits act as mediators that enable full gray scale capability by controlling the duration and timing of high-current pulses without requiring complex direct control of the LED itself.
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
Enables full gray scale display at high current density with high light emitting efficiency, reducing energy consumption and cost, while avoiding flicker perception and hardware implementation difficulties.
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 sub-circuit configured to output a gray scale current signal to an element to be driven, and a gating sub-circuit. The gating sub-circuit is coupled to a scan signal terminal, a reset signal terminal, a gating data signal terminal and a pulse voltage signal terminal; the gating sub-circuit is configured to drive the element to be driven to continuously emit light under the control of a scan signal from the scan signal terminal and a gating data signal from the gating data signal terminal, and to drive the element to be driven to intermittently emit light under the control of a reset signal from the reset signal terminal, the gating data signal from the gating data signal terminal, and a pulse voltage signal from the pulse voltage signal terminal.