Philips BDL4220QL Dark Dot Defects, Proximity of Pixel Defects, Pixel Defect Tolerances, Mura

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BDL4220QL

7.4.Dark Dot Defects

Black dot defects appear as pixels or sub-pixels that are always dark or “off”.These are the examples of black dot defects:

One dark dot

Two adjacent dark dots = 1 pair of dark dots

Two dark dots, specifications defines the minimum distance between dark dots

7.5.Proximity of Pixel Defects

Because pixel and sub-pixels defects of the same type that are nearby one another may be more noticeable, Philips also specifies tolerances for the proximity of pixel defects. In the table below you can find specifications about:

Allowed amount of adjacent dark dots = (adjacent dark dots =1 pair of dark dots)

Minimum distance between dark dots

Total no. of all defective dots

7.6.Pixel Defect Tolerances

In order to qualify for repair due to pixel defects during the warranty period, a PDP / TFT panel in a Philips Plasma / LCD- display must have pixel or sub- pixel defects exceeding the tolerances listed in the following table.

BRIGHT DOT EFFECT

ACCEPTABLE LEVEL

1 lit sub pixel

2

 

 

BLACK DOT EFFECT

ACCEPTABLE LEVEL

1 dark sub pixel

10

 

 

TOTAL DOT DEFECTS OF ALL TYPES

12

NOTE: * 1 or 2 adjacent sub pixel defects = 1 dot defect

 

7.7.MURA

Dark spots or patches may occasionally appear on some liquid crystal display (LCD) panels.This is known within the industry as Mura, which is a Japanese term for “unevenness.” It is used to describe an irregular pattern or area in which uneven screen uniformity appears under certain conditions. Mura is a result of the deterioration of the liquid crystal alignment layer and is most commonly caused by long-term operation under high ambient temperatures. It is an industry- wide phenomenon and Mura is not repairable. It is also not covered by our warranty terms.

Mura has been around since the introduction of LCD technology and with screens getting bigger and in operation 24/7, many displays are running in low light conditions.This all adds to the possibility of Mura affecting displays.

HOW TO SPOT MURA

There are many symptoms of Mura and also multiple causes. Several of these are listed below:

Impurities or foreign particles in the crystal matrix

Uneven distribution of LCD matrix during manufacturing

Non-uniform luminance distribution of the backlight

Panel assembly induced stress

Flaws within the LCD cells

Thermal induced stress – high temperature operation over long periods of time

HOW TO AVOID MURA

Although we can not guarantee the complete eradication of Mura every time, in general the appearance of Mura can be minimized by these methods:

Lower the backlight brightness

Use a screen saver

Reduce the ambient temperature around the unit

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Contents BDL4220QL When connecting and using your Public Safety InstructionsKnow These Safety Symbols Read and follow these instructionsImportant Safety Instructions Federal Communications Commission FCC Notice U.S. Only Regulatory InformationCE Declaration of Conformity Information for U.K. only Polish Center for Testing and Certification NoticeHow to connect a plug Electric, Magnetic and Electronmagnetic Fields EMFChina RoHS 中国电子信息产品污染控制标识要求Waste Electrical and Electronie Equipment North Europe Nordic Countries InformationEnd-of-Life Disposal VarningTable Of Contents Installation Notes Unpacking and InstallationPackage Contents UnpackingMounting on a Wall Ventilation Requirements for enclosure locatingControl Panel Remote control sensor and power status indicatorParts and Functions ButtonInput/Output Terminals List Remote ControlGeneral functions OptionsOperating range of the remote control Inserting batteries in the remote controlHandling the remote control Connecting External Equipments Connection1. RS232C control connection optional Connecting Multiple DisplaysIR Pass-through Connection optional IR connection optionalWire-connecting to Network optional To setup the networkOperation Playing music files Play optionsPlay multimedia files from USB device Movie options Playing movie filesPlaying photo files Start a slideshowUsing the remote control Change your settingsSettings Quick Picture and SoundSound menu Digital Crystal ClearNetwork Settings General settings menuSdtv Resolution Input modePC Resolution Hdtv ResolutionTypes of Pixel Defects + Dot Definition Pixel Defect PolicyPixels and Sub-pixels Bright Dot DefectsPixel Defect Tolerances Dark Dot DefectsProximity of Pixel Defects MuraFront Panel Cleaning Instructions Cleaning and TroubleshootingCleaning Cabinet Cleaning InstructionsTroubleshooting Symptom Possible Cause RemedyIn/Out Terminals Technical SpecificationsDisplay General