Pixel Driving Circuit for Time-Phased LED Heat Control
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face challenges in maintaining high luminous efficiency over time due to heat accumulation, which reduces their stability and efficiency, especially when operating at high current densities for extended periods.
Innovation Solution
A pixel driving circuit is designed with a light-emitting diode chip that includes multiple light-emitting portions connected in series and parallel, allowing independent control of each portion to alternately emit light or emit simultaneously, thereby managing current density and reducing heat accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional LEDs operate at high current densities for extended periods, then brightness and luminous output are improved, but heat accumulation increases causing reduced stability and luminous efficiency
Solution Approach 1:
The LED chip is divided into multiple light-emitting portions (first, second, third portions) that can be independently controlled. By segmenting the single LED into multiple portions, the circuit can activate only the necessary number of portions based on the gray scale level, thereby reducing overall current density and heat generation while maintaining required brightness output.
Solution Approach 2:
The patent implements dynamic control of light-emitting portions through a switching circuit that adjusts which portions are active based on gray scale levels. This dynamic adjustment allows the system to optimize between brightness output and heat management in real-time, activating fewer portions at lower gray scales to reduce heat accumulation.
2Illumination intensity
If multiple light-emitting portions are activated simultaneously to achieve high gray scale display, then brightness is improved, but current density and heat generation increase
Solution Approach 1:
The patent employs time-division multiplexing where light-emitting portions are activated in different time periods or phases. By controlling the timing of activation for different portions (first, second, third portions) through the switching circuit, the system can achieve high gray scale brightness through temporal sequencing rather than simultaneous activation, thereby distributing the current load and reducing peak heat generation.
3Device complexity
If a single light-emitting portion is used, then device complexity is reduced, but the ability to manage current density and reduce heat accumulation is limited
Solution Approach 1:
The LED chip is divided into multiple light-emitting portions (first, second, third portions) that can be independently controlled. By segmenting the single LED into multiple portions, the circuit can activate only the necessary number of portions based on the gray scale level, thereby reducing overall current density and heat generation while maintaining required brightness output.
Solution Approach 2:
The patent changes the operational parameters by controlling different numbers of light-emitting portions based on gray scale levels. At lower gray scales, fewer portions are activated to reduce current density and heat generation, while at higher gray scales, more portions are activated to increase brightness. This parameter adjustment optimizes the balance between thermal management and display performance.
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
This design enhances luminous efficiency by optimizing current density and reducing heat-related issues, improving the stability and longevity of the LED chip during both low and high gray scale displays.
Implementation Method 1
The light-emitting diode chip includes a plurality of light-emitting portions. The light-emitting diode chip is configured to, with cooperation of the first voltage signal from the second node and a second voltage signal received at the second voltage signal terminal, drive the plurality of light-emitting portions to emit light in different periods of time respectively
Data Source
AI summary
A pixel driving circuit includes a data writing circuit, a light-emitting control circuit, a switching circuit and a light-emitting diode chip. The data writing circuit is electrically connected to a first scanning signal terminal, a data signal terminal and a first node. The light-emitting control circuit is configured to transmit a first voltage signal received at the first voltage signal terminal to a second node. The switching circuit includes switching transistors. The light-emitting diode chip is electrically connected to the second node. The light-emitting diode chip includes light-emitting portions. The light-emitting diode chip is configured to drive the light-emitting portions to emit light in different periods of time respectively or drive at least two light-emitting portions to emit light in a same period of time. At least part of the light-emitting portions are sequentially connected in series through at least one switching transistor.