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
TECHNICAL NOTE“Grade A” vs. “Grade B” LCD Panels
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)
TECHNICAL NOTE“Grade A” vs. “Grade B” LCD Panels
SURFACE DEFECTSThere are two types of surface defects, scratches and dents/bubbles. These defects are defined per the
criteria below.
Definition of surface defects:
Page 3 of 4
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.
TECHNICAL NOTE“Grade A” vs. “Grade B” LCD Panels
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:
Page 4 of 4
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.
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