MicroLED Subpixel Circuit PWM Control for Luminous Efficiency
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Solution Overview
Problem
MicroLEDs experience low luminous efficiency and high power consumption at low grayscale values due to low current density, making it challenging to achieve desired brightness levels effectively.
Innovation Solution
A subpixel circuit comprising a data voltage write-in circuit, driving circuit, storage circuit, light-emitting time control circuit, and light-emitting control circuit, which allows for precise control of data voltage and light-emitting time to optimize current density and luminous efficiency, enabling the MicroLED to operate at higher efficiency by adjusting current density and light-emitting time in accordance with grayscale values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If current density is reduced to achieve lower brightness levels, then grayscale control is improved, but luminous efficiency deteriorates
Solution Approach 1:
The patent applies periodic action by using pulse-width modulation (PWM) to control the light-emitting element. Instead of varying current density continuously, the circuit switches the current on and off periodically with different duty cycles. This allows grayscale control through time-domain modulation while maintaining high current density during the on-state, thus preserving luminous efficiency while achieving precise brightness levels.
Solution Approach 2:
The patent changes the control parameter from current density to light-emitting time duration. By using a storage capacitor to maintain voltage and controlling the duration of current flow through PWM signals, the system achieves grayscale control without relying on low current density, thereby avoiding the luminous efficiency penalty associated with reduced current.
2Loss of energy
If current density is increased to improve luminous efficiency, then energy efficiency is improved, but power consumption increases
Solution Approach 1:
The circuit uses periodic PWM signaling to control the light-emitting element, switching at high frequency with variable duty cycles. This allows the element to operate at high current density (high luminous efficiency) only during the brief on-periods, while remaining off during the remainder of the cycle, thus achieving overall low power consumption while maintaining high efficiency during active emission.
Solution Approach 2:
The patent implements dynamic control of the light-emitting element through real-time adjustment of PWM duty cycles. The driving circuit dynamically switches between different current levels and time durations based on the desired grayscale value, optimizing the balance between luminous efficiency and power consumption for each display frame.
3Device complexity
If simple current control is used to reduce circuit complexity, then device complexity is reduced, but control precision over light-emitting time deteriorates
Solution Approach 1:
The patent segments the control function into distinct modules: a storage capacitor for voltage maintenance, a driving transistor for current control, and PWM control circuitry for timing precision. This segmentation allows each component to specialize in one aspect of control, achieving precise light-emitting time control without requiring overly complex integrated circuitry.
Solution Approach 2:
The storage capacitor acts as an intermediary element that decouples the voltage supply from the current control. It maintains stable voltage during the light-emitting period while allowing the driving transistor to precisely control the current flow duration through gate voltage modulation, thereby achieving accurate timing control without direct complex circuitry.
Data Source
AI summary
What is described above are optional embodiments of the present disclosure. It should be noted that, for those of ordinary skills in the art, several modifications and refinements may be made without departing from the principle of the present disclosure. These modifications and refinements should also be considered to be within the scope of the present disclosure. What is described above are optional embodiments of the present disclosure. It should be noted that, for those of ordinary skills in the art, several modifications and refinements may be made without departing from the principle of the present disclosure. These modifications and refinements should also be considered to be within the scope of the present disclosure.