Pixel Driving Circuit for Micro LED Brightness Stability
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Solution Overview
Problem
In Micro LED and Mini LED display devices, the brightness and luminous efficiency are affected by the current density of the driving current, leading to unstable brightness and high energy consumption when the current density is low, and existing methods primarily control brightness by adjusting the driving current without effectively managing luminous duration.
Innovation Solution
A pixel driving circuit comprising a driving control sub-circuit and a driving duration control sub-circuit that writes data signals and voltage signals to control both the magnitude and duration of the driving current, ensuring high current density and stable brightness across various gray scales.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the driving current is reduced to lower power consumption, then energy consumption decreases, but brightness becomes unstable and luminous efficiency drops
Solution Approach 1:
The patent applies dynamics by making the driving current adaptable through pulse width modulation (PWM). The driving current is dynamically adjusted by controlling the duration of current pulses rather than using a fixed low current level. This allows the system to maintain high current density during active emission periods to ensure stable brightness and luminous efficiency, while reducing overall power consumption by controlling the temporal distribution of current delivery.
Solution Approach 2:
The patent implements periodic action through pulsed current delivery to the light-emitting element. Instead of continuous current flow, the driving circuit delivers periodic current pulses with controlled width and frequency. This periodic modulation allows the element to receive high current density during each pulse for stable light emission, while the overall energy consumption is reduced by the duty cycle control, resolving the contradiction between power consumption and brightness stability.
2Use of energy by moving object
If the driving current is reduced to lower power consumption, then energy consumption decreases, but luminous efficiency drops
Solution Approach 1:
The driving circuit dynamically controls current delivery to maintain optimal current density during emission periods. By using PWM techniques, the circuit ensures that when current is delivered, it does so at high density levels that maximize luminous efficiency of the LED element, while the overall power consumption is managed through temporal control of current delivery duration and frequency.
Solution Approach 2:
The periodic pulsed current delivery ensures that the light-emitting element operates at peak efficiency during each active period. The pulse width and frequency are optimized to maintain high current density during emission, maximizing luminous efficiency, while the off-periods reduce average power consumption. This periodic operation mode resolves the contradiction by decoupling instantaneous efficiency from average power consumption.
3Illumination intensity
If traditional brightness control methods are used, then brightness can be adjusted, but luminous duration cannot be effectively controlled
Solution Approach 1:
The patent segments the brightness control function into two independent control dimensions: amplitude control for brightness intensity and pulse width control for luminous duration. The driving circuit separately manages the current amplitude (affecting brightness) and the pulse duration (affecting luminous duration), allowing independent adjustment of both parameters without interfering with each other, thus resolving the limitation of traditional single-dimension control methods.
Solution Approach 2:
The driving circuit dynamically controls both the amplitude and temporal characteristics of the driving current through PWM modulation. By independently adjusting the current amplitude and pulse width, the system can dynamically control both brightness intensity and luminous duration, providing flexible and precise control over the light emission characteristics that overcomes the limitations of traditional control methods.
Data Source
AI summary
A pixel driving circuit includes a driving control sub-circuit and a driving duration control sub-circuit. The driving control sub-circuit includes a first driving sub-circuit connected to a first node. The driving control sub-circuit is configured to be connected to an element to be driven. The driving control sub-circuit is configured to output a driving signal to drive the element to be driven to operate. The driving duration control sub-circuit includes a second driving sub-circuit connected to a second node. The driving duration control sub-circuit is configured to write a first voltage signal into the second node, write a third voltage signal into the second node, and transmit a second voltage signal to the first node in response to a voltage variation at the second node to stop the first driving sub-circuit from outputting the driving signal, so as to control an operating duration of the element to be driven.