TECHNICAL NOTE “Grade A” vs. “Grade B” LCD Panels
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.
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.
PIXEL DEFECTS
There 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.
SURFACE DEFECTS
There are two types of surface defects, scratches and dents/bubbles. These defects are defined per the criteria below.
Definition of surface defects:
The tables below show the differences between Grade A and Grade B LCD panels in terms of allowable surface defects.
FOREIGN MATERIAL CONTAMINATION
There 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:
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.
