Dead Pixel Policy.

[Danno]

***Please do not post replies in this topic. If you are unsure about any of the information please start a new topic.***

All TFT manufacturers have different policies on the amount of dead it takes to class a monitor as faulty. There is an ISO (International Standards Organization) that many manufacturers follow.

ISO 13406-2 (Class II) standard which covers the maximum number pixels on any given panel.

The pixel faults are defined in the following way:

Type 1) constant bright pixel
http://forum.novatech.co.uk/files/pixel01.gif
Type 2) constant dark pixel
http://forum.novatech.co.uk/files/pixel02.gif
Type 3) defect pixel, either constantly bright (red, green, blue or constantly dark)
http://forum.novatech.co.uk/files/pixel03.gif
Type 4) fault cluster, the number of defective pixels in a 5 x 5 pixel square.
http://forum.novatech.co.uk/files/pixel04.gif

Class I monitors are guaranteed products which do not have any defects at all however it is rare to find a manufacturer offering such high quality products.

Class II specification consists of the following faults permissible: 2 x Type 1, 2 x Type 2, 5 x Type 3 and 2 x Type 4.
Class I monitors are guaranteed products which do not have any defects at all however it is rare to find a manufacturer offering such high quality products.
Class II specification consists of the following faults permissible: 2 x Type 1, 2 x Type 2, 5 x Type 3 and 2 x Type 4.

The number of permissible pixel faults can be calculate with the following function:
(number of errors = number of pixels of the physical resolution x number of errors in the pixel fault category / 1.000.000) with rounding up upward (there it no half errors gives). The following table defines the maximum permissible number of pixel faults for the respective resolution types validly for the pixel error class II.
Panel type

http://forum.novatech.co.uk/files/pixel05.gif

Based on the standard ISO 13406-2 the customer can use the tables explained above as basis for the evaluation of the pixel error tolerance. Excess of one of the specified border criteria leads to the entry into force of the warranty claim.

Hardware review website http://www.tomshardware.com have been in touch with different monitor manufacturers to find out what there dead pixel policy is. Below are the results. The full article can be found here.

http://www.tomshardware.com/2003/03/19/penalty/

http://forum.novatech.co.uk/files/th1.gif

http://forum.novatech.co.uk/files/th2.gif

http://forum.novatech.co.uk/files/th3.gif

http://forum.novatech.co.uk/files/th4.gif

http://forum.novatech.co.uk/files/th5.gif

http://forum.novatech.co.uk/files/th6.gif

[Danno]

More on dead pixels. Over time i will check differnet manufacturers policies to see whats what.

Viewsonic

LCD Pixel Criteria

ViewSonic is committed to customer satisfaction by providing the highest quality products in the industry. The result is that our LCD displays generally have very few non-performing pixels. For example, an 18" SXGA (1280 x 1024) display has nearly 4 million sub-pixels. A product exhibiting 7 non-performing pixels would equate to an extremely small 0.00018 percent of the total sub-pixels.

(1280 Horizontal Pixels) * (1024 Vertical Pixels) * (3 sub-pixels per pixel) = 3,932,160 sub-pixels

[(7 non-performing pixels) / (3,932,160 sub-pixels)] * 100% = 0.00018%

To ensure the highest performing displays, ViewSonic sets limits as to the allowable number of pixel anomalies. ViewSonic has adopted the following pixel criteria to supplement our existing three-year limited warranty. This policy applies to all ViewSonic LCD displays during the warranty period.
ViewSonic sets limits on 14" - 15" LCD's at 4 bright sub-pixels, 4 dark sub-pixels, or a combination of 4.
ViewSonic sets limits on 17" - 19" LCD's at 7 bright sub-pixels, 7 dark sub-pixels, or a combination of 7.
ViewSonic sets limits on 20" & greater LCD's at 10 bright sub-pixels, 10 dark sub-pixels, or a combination of 10.
It is possible that any replacement display may also have some non-performing sub-pixels. This should be considered when requesting a warranty exchange.

Taken from http://www.viewsonic.com/support/qa.cfm ... uestion=01 (http://www.viewsonic.com/support/qa.cfm?topic=lcd&question=01)

[Danno]

GNR and Di-fusion

Warranty Claims in the event of Pixel Faults in LCD Monitors78

General Information

Pixel faults are the result of a defective transistor in the display. In places where a transistor fails to connect through (or always connects), a continuously bright (or continuously dark) spot is visible. In addition, there are so-called sub pixels that are as a rule illuminated red, green or blue. Unfortunately it is not possible to avoid pixel faults completely when a TFT panel is manufactured because the scrap percentage would be excessively high, leading to an unacceptable increase in the price of the panel and of the entire monitor.

The International Standards Organisation have developed a standard ISO 13406-2:2002 (Titled - Ergonomic requirements for work with visual display based on flat panels), in co-operation with the manufacturers of monitors, panels and several expert testing companies e.g. TÜV Rheinland, which addresses amongst others the topic of pixel faults and defines several classes of failure.

The ISO standard (ISO 13406-2) divides displays into classes:-

* Class I - which is assigned to LCD's that show no pixel faults
* Class II - This permits several pixel faults to be admissible depending on their position and colour, per one million pixels each.

All PGE LCD monitors, branded GNR, Di-fusion & Haier, have been certified according to ISO13406-2. According to this standard, warranty claims of the customers are also justified in the event of pixel faults, if your product exceeds those guidelines listed below.

Definition of Pixel Faults under ISO 13406-2 Guidelines

Acceptable malfunctioning pixels by class & type per MILLION pixels:
Type 1 2 complete pixels constantly illuminated (white spot)
Type 2 2 complete pixels not illuminated (black spot)
Type 3 5 sub pixels constantly on or off or an intermittent fault where it may blink or show a pixel as a base colour (Red, Blue, Green, Cyan, Magenta or Yellow)
Cluster of Types 2 x Types 3 (see definition above) faults within a 5 x 5 block of pixels
Resolution Pixel Count

1024 x 768 6,432
1280 x 1024 1,310,720
1600 x 1200 1,920,000

Click here to download the full TUV Rheinland document explaining ISO 13406-2
http://www.pgeaftercare.com/downloads/TUVRheinland.pdf

Taken from http://www.pgeaftercare.com/LCDPixelFailure.htm

[Danno]

Sony

Sony guarantees to meet the international standard ISO13406-2 (Ergonomic requirement for work with visual displays based on flat panels) Class II Specification. (see first post)

Taken from http://www.sonydigital-link.com/FAQ/XML ... q.asp?l=en (http://www.sonydigital-link.com/FAQ/XML/CDP/faq.asp?l=en) (general information and then what is sony policy for dead pixels).

[Danno]

Videoseven

Why do LCDs have pixel failures?

A pixel or picture element, is composed of three sub-pixels in the primary colors of red, green, and blue. At each pixel position in an AMLCD (active matrix liquid crystal display) flat screen monitor, three cells of liquid crystal material form the red, green and blue sub-pixels that together allow the full range of colors to be displayed. Individual transistors are arranged in an array on the rear glass to control each sub-pixel. An anomaly on any one of these individual transistors will cause a bright or dark pixel to appear.

Until now it is not possible to produce any LCDs without pixel failures. The ISO 13406 therefore describes certain limits for LCDs. Please find the limits for each V7 LCD in our product description.

Product descriptions can be found here. http://www.videoseven.com/website/displ ... /index.php (http://www.videoseven.com/website/displays/en/produkte/displays/index.php)

Taken from http://www.videoseven.com/website/displ ... /index.php (http://www.videoseven.com/website/displays/en/support/faq/displays/index.php)

[Danno]

Hyundai ImageQuest

Hyundai ImageQuest strives to provide the highest quality LCD display products in the industry.
Your Product meets the Class 2 specifications under the ISO 13406-2 industry guidelines for LCD monitors.

LCD monitors use a technology based on pixels.
A pixel is a combination of three sub-pixels (red, green and blue) that produce a specific color.
There are millions of these sub-pixels on each LCD screens.
Pixel faults on LCD screens can be comprised of whole pixels or sub-pixels either going dark,
staying permanently lit or flashing.

ISO 13406-2 standard allows for a certain number of pixel faults based on the number of
total pixels in the monitor (determined by the screen size).
Hyundai ImageQuest will replace an LCD monitor during the
Warranty Period if it meets the following criteria:

- For 15” Monitor – 7 or more bad pixels
- For 17” and 19” Monitors – 10 or more bad pixels
- For 21” ~ 24” Monitors – 17 or more bad pixels
Information taken from http://www.hyundaiq.com/cus05.asp

[Danno]

Digimate

Dead Pixels
Blemishes and pixel failures are covered in accordance with ISO 13406-2.

Digimate Limited uses ISO13406-2 as the standard to determine the acceptable number of failed pixels and sub-pixels on an LCD panel.

The standard defines the various failure modes and acceptable failures per 1,000,000 pixels.No more than 4 defective pixels per 1,000,000 pixels

Pixel Fault
Type 1 - continuously fully luminous - maximum 2 per 1, 000, 000 pixels
Type 2 - "dead" pixel - maximum 2 per 1,000,000 pixels
Type 3 - R, G, B defective subpixels - maximum 5 per 1, 000, 000 pixels
Dead Pixels
No more than 4 defective pixels per 1,000,000 pixels
No defective pixel is allowed within 30mm of the centre of the panel.
No defective pixels are allowed within 5mm of each other.
We have summarized in the table below how this relates to the different sizes of Digimate screen.
http://forum.novatech.co.uk/files/Digimate.jpg

Information taken from http://www.digimate.com.hk/registration ... policy.htm (http://www.digimate.com.hk/registration/warrantypolicy.htm)