imperfect plasma pixels.pdf

5/24/2018 Imperfect plasma pixels.pdf

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PlasmaSync

Technical White Paper

Version 2.0, Issued 11/02

Subject: Imperfect pixels in Plasma displays

This document provides information on the nature of pixel imperfections in plasma display panels and

tolerances for pixel imperfections in NECs plasma display panels.

Background

Plasma manufacturers set limits as to how many imperfect pixels are acceptable for a panel based on acombination of user feedback and manufacturing cost data. The goal in setting these limits is to achievereasonable product pricing while minimizing distraction from imperfect pixels. However, because the

panel contains literally millions of pixel elements, it is understandable that absolute perfection cannot be

achieved in every panel.

Pixel outage is difficult to assess during the manufacturing process of plasma display panels. Only upon

completed assembly can an individual panel be assessed for imperfect pixels. The more units that are

classified as imperfect due to pixel malfunction, the lower the overall yield. This results in scrapped

materials, and, therefore, higher production costs. By setting the optimal balance between production cost

and out pixel tolerance, yield rates are increased, production costs are minimized and the savings are passedon to the market in the form of more affordably priced product.

These issues are consistent throughout the industry and are also present for other types of fixed matrixdisplay technologies including LCD panels.

Types of pixel imperfections

Pixel imperfections can be classified in one of two ways. Dark pixel defects are the result of pixels that do

not light and appear as black holes in the image. They are typically visible only on static images. Bright

pixel defects are the result of a pixel element that is stuck in the lit state and appear as a red, green or

blue spot in the screen image.

Dealing with Imperfect Pixels

Each pixel in the plasma panel is composed of a separate red, green and blue sub-pixel. It is these sub-

pixels, or pixel elements, that are considered when counting the number of pixels present for the purposesof determining defect ratios. Therefore, the base number of pixels is equivalent to the native resolution of

the panel times three. In the case of a Wide VGA 853x480 resolution panel this equates to over 1.2 million

pixel elements. In the case of a Wide XGA 1365x768 panel this totals to over 3.1 million pixel elements.

NEC strives for perfection in the manufacturing of its plasma display panels. With all of these

considerations in mind, NEC has set out pixel tolerances in its plasma panels at less than 1/1000 of a

percent. This represents an exceptionally high quality standard that is remarkable from a technicalstandpoint due the extremely large number of pixel elements present in the panels.

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In each of NECs plasma panel modules the overall threshold for pixel imperfections are as follows:

Bright Pixel 0.00025%

Dark Pixel 0.00095%

This specification ensures the quality of NECs plasma panels to at least 99.975% of perfection, which is

an extremely high level for any display technology.

Conclusion

NEC manufactures plasma display panels to very exacting standards of quality. None-the-less, due to the

sheer number of elements in a panel and the nature of the panel fabrication process it is likely that a minute

number of imperfect pixels will be present in any given panel. NEC attempts to set out pixel tolerance

specifications to strike an optimal balance between cost and viewer comfort.

NEC Solutions (America), Inc. stands behind every PlasmaSync monitor sold and will go to reasonable

lengths to ensure customer satisfaction with regard to the quality of our plasma panels.


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