technical note - ndssi.com

TECHNICAL NOTE“Grade A” vs. “Grade B” LCD Panels

The number of defects, and in turn the level of quality,

of the final manufactured product varies significantly.

A leading manufacturer of LCD panels used in today’s

surgical flat panel displays sort the LCD panels they

produce, classifying them into different “Grades”

based upon defect criteria specifications (“Grade

A” or “Grade B”). Since “Grade A” LCD panels have

fewer defects and must meet a more stringent defect

criteria specification, they are higher quality, and therefore higher cost. “Grade B” panels have

a larger number of allowable defects, and are therefore lower quality and lower cost.

NDSsi uses only “Grade A” LCD panels in all of its products, while many competitors use “Grade B”

panels in order to save cost, and as a result compromise quality. In medical applications, it is important not

to compromise the quality of the displayed image since it is often the basis for making clinical decisions.

The following tables and images show the differences between “Grade A” and “Grade B” LCD panels in

terms of different types of allowable defects.

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INTRODUCTION

NDSsi and other companies that produce surgical LCD displays purchase the actual LCD panels

(commonly referred to as “Glass”) from one of only a handful of manufacturers in Asia. These LCD

panels are relatively difficult and expensive to produce. There is

no such thing as a “perfect” LCD panel that has absolutely

zero defects. There is a wide variety of different defects

that LCD panels can have, ranging from “stuck”

(bright) or “dead” (dim) pixels to surface

“bubbles” and foreign material

contamination inside the panel.

Bare LCD Panel

NDS Radiance® Surgical Display Line


PIXEL DEFECTSThere are essentially two different types of pixel defects, bright (stuck pixels) and dark (dead pixels).The

table and images below show the differences between Grade A and Grade B LCD panels in terms of

allowable pixel defects.

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Defect Grade A: Max Quantity Allowed

Grade B: Max Quantity Allowed

Bright Pixel Defect (Stuck) 0 5Adjacent Bright Pixel Defects (Stuck) 0 1Dark Pixel Defect (Dead) 5 7Adjacent Dark Pixel Defect (Dead) 2 3Total Dot Defects (Bright + Dark) 5 12Pixel Defect Minimum Distance > 15 mm Not Specified

Grade A Panel Grade B Panel

Bright Defects(Stuck Pixels)

Dark Defects(Dead Pixels)

Bright Defects(Stuck Pixels)

Dark Defects(Dead Pixels)


SURFACE DEFECTSThere are two types of surface defects, scratches and dents/bubbles. These defects are defined per the

criteria below.

Definition of surface defects:

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DefectGrade A Grade B

Qty Allowed Width (mm) Length (mm) Qty Allowed Width (mm) Length (mm)

Scratches 22 0.05≤W≤0.1 0.3≤L≤3.0 3 0.05≤W≤0.1 0.3≤L≤3.0

LG Display’s Incoming Inspection Standard

1.0May/15/’12

Do not copy or distribute. Copyright ⓒ 2012 LG Display8

3.0 Inspection Criteria

3.1.2. Dark Dot

Defect Modes Dark Dot types Inspection standards

Pixel off

Inspection Patterns :White,Half Gray

ND Filter

O.K Type 1 Type 2 Type 3

Observer

LCM

30~40cm

90±5 ˚

<How to apply ND Filter>

ND Filter

3.2. Polarizer Defects

Items Criteria(acceptable level)

Scratches Linear

Width 0.05≤W≤0.1 1. Extraneous substance which can be wiped out, like Finger Print, Particles, are not considered as a defect.

2. Defects which are on the Black Matrix(outside of Active Area) are not considered as a defect.

Length 0.3≤L≤3.0

Quantity N≤2

Dent or Bubble Circular

Diameter 0.2≤D≤0.4

Quantity N≤2

Defect modes Definition Inspection standards

Scratches Inspection patterns :White, Half

GrayDent or Bubble

L>4W : considered as LinearL≤4W : considered as Circular

a

b

D= (a+b)/2

W: widest point [mm]L : longest point [mm]

DefectGrade A Grade B

Quantity Allowed Diameter (mm) Quantity Allowed Diameter (mm)

Dent or Bubble 22 0.2≤D≤0.4 2 0.2≤D≤0.5

The tables below show the differences between Grade A and Grade B LCD panels in terms of allowable

surface defects.


FOREIGN MATERIAL CONTAMINATIONThere are two types of foreign material contamination defects, linear and circular. These defects are

defined per the criteria below.

Definition of foreign material contamination defects:

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Contamination Defect

Grade A Grade B

Width (mm) Length (mm) Width (mm) Length (mm)

Linear 0.05≤W≤0.1 0.3≤L≤2.5 0.05≤W≤0.1 0.3≤L≤3.0

LG Display’s Incoming Inspection Standard

1.0May/15/’12

Do not copy or distribute. Copyright ⓒ 2012 LG Display9

3.3 Foreign Material (Polarizer, Backlight)

Items Criteria(acceptable level)

Linear

Width 0.05≤W≤0.1

In the case of foreign material in Polarizer which appears bright, it is based on inspection standards of Bright Dot. (ND Filter)

Length 0.3≤L≤2.5

Quantity N≤3

CircularDiameter 0.2≤D≤0.4

Quantity N≤3

Defect modes Definition Inspection standards

Linear Inspection Pattern :White, Half

Gray

Circular

W

L=A+B

L=A+B+C

L=A+B

a

b

L>4W : considered as LinearL≤4W : considered as Circular

D= (a+b)/2

W: widest point [mm]L : longest point [mm]

3.4 Mura

Mura which appears in the screen when the LCM displayed. (Using 2% ND Filter)It would not be counted as Mura, although it is visible with naked eyes

Contamination Defect

Grade A Grade B

Diameter (mm) Diameter (mm)

Circular 0.2≤D≤0.4 0.2≤D≤0.5

The tables below show the differences between Grade A and Grade B LCD panels in terms of the size of

allowable foreign material contamination defects.

© 2012 NDS Surgical Imaging. Features and specifications are subject to change without notice. NDS products are capable of displaying radiology (PACS) images for reference purposes only. Products may not be available in all markets and are subject to the regulatory or medical practices that govern individual markets. Always refer to the package insert, product label and/or user instructions before using any NDSsi product. Contact your NDSsi representative for more information. All trademarks are property of their respective owners.

Doc# 72H0010 rev A

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