Pixel Drive Circuit for Micro LED Gray-Scale Control
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Solution Overview
Problem
Micro LED displays face challenges in maintaining LEDs in a high-efficiency operating range to achieve gray-scale cutting due to varying luminous efficiency with different driving currents.
Innovation Solution
A pixel drive circuit with a power supply line, pulse amplitude modulation unit, and pulse width modulation unit is implemented, using transistors and capacitors to control driving currents by varying voltage levels, ensuring the light-emitting element operates within a high-efficiency range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If driving current is increased to maintain high-efficiency operating range, then luminous efficiency is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic pulsed driving of the Micro LED through pulse width modulation (PWM), where the LED is driven at high current only during the illumination phase and turned off during the non-illumination phase. This periodic action allows the LED to operate in high-efficiency high-current range when needed while avoiding continuous high-power consumption, thus resolving the contradiction between luminous efficiency and power consumption.
Solution Approach 2:
The patent dynamically changes the driving current parameters through pulse amplitude modulation (PAM) and pulse width modulation (PWM), adjusting the current magnitude and duration according to display requirements. This parameter change approach enables the system to optimize between luminous efficiency and power consumption by selecting appropriate current levels and pulse widths for different display scenarios.
2Manufacturing precision
If driving current is varied to achieve gray-scale cutting, then display quality is improved, but control complexity increases
Solution Approach 1:
The patent segments the driving control into two independent functional modules: pulse amplitude modulation unit for controlling current magnitude and pulse width modulation unit for controlling illumination duration. This segmentation allows each module to specialize in one aspect of gray-scale control, simplifying the overall control logic while achieving precise gray-scale cutting through the combination of amplitude and width adjustments.
Solution Approach 2:
The patent designs a universal control architecture where the same transistor-based circuit structure can achieve multiple functions: PAM for amplitude control, PWM for width control, and their combinations for various gray-scale levels. This multi-functional design reduces control complexity by using a unified circuit framework that handles different gray-scale requirements through parameter variation rather than requiring separate dedicated circuits for each function.
3Loss of energy
If Micro LED is driven at high current continuously, then luminous efficiency is maintained, but LED lifetime decreases
Solution Approach 1:
The patent applies periodic pulsed driving through PWM, where the Micro LED operates at high current only during illumination phases and remains off during non-illumination phases. This periodic action pattern allows the LED to achieve high luminous efficiency during active periods while avoiding continuous high-current stress that would reduce lifetime, thus balancing efficiency and durability through time-limited high-current operation.
Data Source
AI summary
Disclosed are a pixel drive circuit, a driving method, and a display panel. The pixel drive circuit includes a light-emitting element, a power supply line, and a pulse amplitude modulation unit and a pulse width modulation unit connected between a high-potential power supply of the power supply line and an anode of the light emitting element. The pulse amplitude modulation unit provides driving currents with different amplitudes to the light emitting element. The pulse width modulation unit includes a second drive transistor, a first transistor and a second transistor, and a pulse width modulation circuit. The pulse width modulation circuit generates a corresponding drive signal to control the first transistor or the second transistor to be turned on based on the first data voltages during a luminescence phase, and controls the second drive transistor to be turned on to control the duration of the driving currents of the light-emitting element.