LCD Protection Circuit for Laser Trimming Elimination

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Conventional liquid crystal display (LCD) manufacturing processes are costly due to the need for laser trimming of data lines and are vulnerable to electrostatic discharge, which slows down the turning-off process of switching elements during inspection.

Innovation Solution

Incorporating a protection circuit with transistors and a storage capacitor connected between signal lines, which forms a guard ring to discharge electrostatic discharge and apply inspection voltages, reducing the need for laser trimming and enhancing the efficiency of visual inspections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If laser trimming process is used to cut data lines after visual inspection, then manufacturing precision can be improved, but manufacturing cost increases

Engineering Contradiction:

Improvedata line cutting precisionVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The protection circuit is designed to perform the data line cutting function automatically during the visual inspection process through voltage application, eliminating the need for subsequent laser trimming. The circuit预先 (in advance) prepares the cutting action by applying inspection voltage that causes controlled breakdown of the data line insulation, achieving both precision and cost reduction.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The protection circuit enables the system to perform its own data line cutting function without requiring external laser trimming equipment. By using the inspection voltage generated within the circuit itself to cause controlled insulation breakdown, the system serves its own manufacturing needs, reducing dependency on additional manufacturing processes.

Inventive Principle:

Principle #25Self-service

2Ease of operation

If switching element is used to control data lines during inspection, then ease of operation is improved, but electrostatic discharge vulnerability increases

Engineering Contradiction:

Improvedata line control during inspectionVSAvoidelectrostatic discharge sensitivity

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The protection circuit acts as an intermediary between the inspection voltage source and the data lines. It includes protective components that mediate the voltage application, preventing direct electrostatic discharge while still enabling the inspection function. The circuit intermediates the harmful effect by controlling and limiting the voltage stress on the data lines.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protection circuit is designed to cushion against electrostatic discharge by incorporating protective elements that absorb or divert excess voltage before it can damage the switching elements or data lines. This beforehand cushioning prepares the system in advance to withstand potential electrostatic stress during inspection operations.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Measurement precision

If inspection voltage is applied to data lines connected together, then measurement precision is improved, but electrostatic discharge risk increases

Engineering Contradiction:

Improvepixel charge rate measurementVSAvoidelectrostatic discharge probability

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The protection circuit serves as an intermediary that safely applies inspection voltage to multiple data lines. It includes protective components that mediate the voltage application across parallel data lines, enabling precise measurement while preventing electrostatic discharge through controlled voltage management and isolation mechanisms.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution decreases manufacturing costs by eliminating the need for laser trimming and protects the LCD from electrostatic discharge, allowing for faster and more reliable visual inspections of pixel luminance.

Implementation Method 1

a storage capacitor connected between the control terminal of the first transistor and the output terminal of the first transistor

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

discharging electrostatic discharge through the protection circuit

Methodology Applied

Scientific EffectElectrostatic Discharge: Electrostatic Discharge

Data Source

PatentUS8279147B2Liquid crystal display device having protective circuits and method of manufacturing the same

Publication Date: 2012.10.02 SAMSUNG DISPLAY CO LTD

AI summary

A display device includes a plurality of pixels connected with a plurality of gate lines and a plurality of data lines, a data driving part applying a data signal to the plurality of data lines, a gate driving part applying a gate signal to the plurality of gate lines, and a plurality of protection circuits connected with the plurality of data lines, wherein each of the plurality of protection circuits comprises a first transistor including a control terminal connected with a first signal line, an input terminal connected with a data line, and an output terminal connected with a second signal line, a second transistor including a control terminal connected with the second signal line, an input terminal connected with the second signal line, and an output terminal connected with the first signal line, and a storage capacitor is connected between the control terminal of the first transistor and the output terminal of the first transistor.