ESD Protection Circuit for Organic Light Emitting Display
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Solution Overview
Problem
Organic light emitting displays are susceptible to defective driving due to electrostatic discharge (ESD), which can damage the display panel and its components, as ESD is transmitted through coupling wiring lines and can exceed the voltage limits of existing protection mechanisms.
Innovation Solution
An ESD protection circuit is integrated between the pad unit and the display unit, scan driver, or data driver, featuring a semiconductor layer, insulating layers, and a conductive layer with physically disconnected ends that are coupled through the semiconductor layer, allowing for ESD dispersion and protection through resistance units and diode-coupled transistors, with additional ESD current paths to manage high voltage ESD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If coupling wiring lines are used to supply driving power and signals from the pad unit to the display panel, then the driving power and signals can be transmitted to the display unit, scan driver, and data driver, but the coupling wiring lines can also transmit ESD from the outside to the inside of the display panel, causing defective driving
Solution Approach 1:
A protective circuit unit is introduced as an intermediary component between the pad unit and the display panel components. This protective circuit unit includes resistance units that are coupled to the coupling wiring lines, serving as a mediator to divert ESD currents away from the vulnerable display panel components while allowing normal driving signals to pass through unaffected.
Solution Approach 2:
The resistance units in the protective circuit unit are designed to normally have high resistance to block current flow during normal operation, but when ESD occurs, the resistance units break down and convert into low resistance paths. This transforms the harmful ESD energy into a controlled current path that safely dissipates the energy through the resistance units, protecting the display panel components from damage.
2Reliability
If resistance units are used to protect against ESD, then ESD currents can be diverted and components protected, but the resistance units may not withstand very high voltage ESD events, requiring additional protection paths
Solution Approach 1:
The protective circuit unit is segmented into multiple functional components: resistance units for normal ESD protection and diode-coupled transistors for high voltage ESD protection. This segmentation allows each component to specialize in handling different voltage levels of ESD events, with the resistance units managing lower voltage events and the diode-coupled transistors activating for high voltage events that exceed the resistance unit breakdown voltage.
Solution Approach 2:
The protective circuit unit employs dynamic characteristics where the diode-coupled transistors remain in a high-impedance state during normal operation and low-level ESD events, but dynamically switch to an active low-impedance state when high voltage ESD events occur. This dynamic behavior allows the circuit to adapt its protection mechanism based on the severity of the ESD event, providing multi-level protection.
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
The ESD protection circuit effectively disperses and manages ESD, preventing damage to the organic light emitting display components and ensuring stable supply of driving power and signals by utilizing resistance units and diode-coupled transistors to divert ESD currents, thereby preventing defective driving.
Implementation Method 1
The protective circuit unit includes a semiconductor layer, insulating layers on the semiconductor layer and a conductive layer on the insulating layer. One region of the conductive layer that overlaps the semiconductor layer is physically disconnected to create two adjacent ends of the conductive layer. The two adjacent ends are coupled to each other through the semiconductor layer.
Implementation Method 2
The protective circuit unit may include diode-coupled transistors. Each of the diode-coupled transistors may include the semiconductor layer, a gate insulating layer on the semiconductor layer, a gate electrode on the gate insulating layer, an interlayer insulating layer on the gate electrode, and source and drain electrodes on the interlayer insulating layer.
Data Source
AI summary
An organic light emitting display. The organic light emitting display includes a display unit, a scan driver, a data driver, a pad unit including a plurality of pads for transmitting driving power or driving signals to at least one of the display unit, the scan driver, and the data driver, and a protective circuit unit coupled between the pad unit and at least one of the display unit, the scan driver, or the data driver. The protective circuit unit includes a semiconductor layer, insulating layers on the semiconductor layer, and a conductive layer on the insulating layer. One region of the conductive layer that overlaps the semiconductor layer is physically disconnected to create two adjacent ends that are coupled to each other through the semiconductor layer. The two adjacent ends of the disconnected conductive layer have recesses and protrusions.