Opposite-Polarity LED Pixel Circuit for ESD-Resistant Displays
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Solution Overview
Problem
LED chips in display devices are vulnerable to electrostatic discharge, leading to potential damage and increased manufacturing costs due to the need for separate protection diodes, which are not directly involved in light emission.
Innovation Solution
A display device configuration where two LED chips per pixel are connected in parallel with opposite polarities, allowing one to function as a light source and the other as a protection diode, sharing a common pixel circuit, thereby enhancing electrostatic withstand voltage and reducing the number of required pixel circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protection diode is connected in parallel to the LED chip to prevent electrostatic discharge damage, then the reliability of the LED chip is improved, but the device complexity increases due to additional components
Solution Approach 1:
The patent merges the protection diode function with the LED chip itself by connecting two LED chips in parallel with opposite polarities. This combination allows one LED chip to serve as the light source while the other serves as the protection diode, eliminating the need for separate protection components and reducing overall device complexity
Solution Approach 2:
The patent makes the LED chip multi-functional by enabling it to serve both as a light source and as a protection diode. The second LED chip can function as a protection diode for the first LED chip, and vice versa, allowing the same component type to fulfill multiple roles within the pixel circuit
2Reliability
If separate protection diodes are added to protect LED chips, then the reliability is improved, but the manufacturing cost increases
Solution Approach 1:
The patent combines the protection function with the existing LED chip structure by using a parallel connection of two LED chips with opposite polarities. This merging eliminates the need for additional separate protection diodes, thereby reducing component count and manufacturing cost while maintaining electrostatic discharge protection
Solution Approach 2:
The patent implements a self-service mechanism where the LED chips themselves provide the protection function. The second LED chip protects the first LED chip from electrostatic discharge, and the first LED chip protects the second, allowing the system to protect itself without external protection components
3Reliability
If two LED chips are connected in parallel with opposite polarities, then the electrostatic withstand voltage is increased, but the pixel circuit complexity increases
Solution Approach 1:
The patent uses inversion by connecting the two LED chips with opposite polarities in parallel. This reverse connection arrangement allows one LED chip to function as a protection diode for the other, enabling the circuit to withstand electrostatic discharge in both polarities while sharing a common pixel circuit
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 configuration increases the electrostatic withstand voltage of the display device, reduces manufacturing costs, and enhances high-definition and transparent display capabilities while maintaining full-color functionality.
Implementation Method 1
a first LED chip including a first anode and a first cathode, a second LED chip including a second anode and a second cathode... The first cathode and the second anode are electrically connected to a second power supply voltage line
Data Source
AI summary
A display device includes a plurality of first pixels and a plurality of second pixels. Each of the plurality of first pixels includes a first LED chip including a first anode and a first cathode, a second LED chip including a second anode and a second cathode, and a first transistor. One of source and drain electrodes of the first transistor is electrically connected to a first power supply voltage line. The other of the source and drain electrodes is electrically connected to the first anode and the second cathode. The first cathode and the second anode are electrically connected to a second power supply voltage line. A first potential of the first power supply voltage line is different to a second potential of the second power supply voltage line.