LCD Damage


The name of the type of damage an LCD can have are referred to the actual damage or cause of damage. 

For example: Damage to an LCD would be a spot, galaxy, scar, scratch, dent, et cetera.

SPECIAL NOTE:

There have been no documented case studies provided to the public to support the information below.  The information provided below are supported by professional experiences in the field under uncontrolled environments. 

It has been my experience that if 10 people have a laptop for at least 10 years, 9 out of the 10 of those people would have damaged their LCD monitors at one point within those 10 years. 

A well-known fact in the IT world is that damage to an LCD screen will only be caused by pressure or temperature, which translates to improper use or abuse from the user. 

PERSONAL OPINION:

The IT world hides this fact from the user by never providing the user with clearly labeled information on proper use and care for their LCD.  Instead, the system manufacture works with the user to warrantee their LCD from improper use or abuse. 

The IT world is no longer repairing LCD screens in the field because of highly reported cases of cross-contamination.  No known reports of injury were documented in the past 10 years.

It has been our experience that 20lbs of direct pressure will cause glass crack or fractures. 

It has also been our experience that 20 degrees Fahrenheit will cause light leakage or pooling and may cause back light and other damage.  

Below is a list of the names of damage and possible causes on an LCD screen.

A good resource for information on LCD’s is going directly to the most common manufacture like ScreenTek, Ltd - URL: http://www.screentekinc.com/

If you have any negative/positive feedback that you would like to share, regarding any data recovery company, please feel free to email me at Articles@McClainSolutions.com


Spot


A spot is a light or dark area on an LCD panel greater than 1 sub pixel.
  • Bright spot defects are best seen with solid dark patterns (black, red, or blue).
  • Dark spot defects are best seen with solid bright patterns (white, yellow, green, or mid-grey).
Small spots are less than 0.1 mm.
Image of spot.

Medium spots are between 0.1 mm and 0.7 mm.
Image of spot.

Large spots are greater than 0.7 mm wide.
Image of spot.


Galaxy


Galaxy is defined as any combination of the three types of spots (small, medium, and large) concentrated in an area.
  • Bright galaxy defects are best seen with solid dark patterns (black, red, or blue).
  • Dark galaxy defects are best seen with solid bright patterns (white, yellow, green, or mid-grey).

Image of galaxy.
Image of galaxy


Scar


A scar is a line that may appear on the LCD panel due to a foreign substance such as hair, lint, worm, etc. trapped between its layers. A region of the LCD panel affected by scars may appear bright, dark, or discolored with respect to the background pattern.
  • Scars are best observed on a white, black, or mid-gray background.
  • Scars differ from scratches because scars are below the surface, but scratches are surface defects.

Image of scar.


Scratch


A scratch is a thin, shallow cut or mark on the external surface of the LCD panel which may be caused by a sharp object.
  • Scratches are best observed with the panel turned off or turned on displaying a solid pattern.
  • Scratches differ from scars because scars are below the surface, but scratches are surface defects.

Image of scratch.


Dent


A dent is a small depression or impression made on the external surface of the LCD panel caused by pressure or a blow. Dents are permanent and visible even when the LCD panel is turned off.

Dents differ from delamination (bubbles) because dents are surface depressions and delaminations are below the surface.
Image of dent.

Delamination


Delamination results in the formation of bubble(s) on the external surface of the LCD panel. High temperature, humidity, and/ or improper assembly of the LCD panel can cause delamination defects. Generally, air or moisture is trapped between the front polarizer and glass substrate, resulting in the formation of bubbles.

Delamination differs from dents in that delamination defects are below the surface, but dents are on the surface.
Image of Delamination.
Image of Delamination.

Pixel


A pixel, also known as a dot, is a combination of three sub pixels, one red sub pixel, one green sub pixel, and one blue sub pixel By varying the levels (intensity) of red, green, and blue sub pixels, LCD panels are able to display different colors.
Image of pixel.

Dark sub-pixel


Dark sub pixel failures occur when one or more sub pixels are locked into the off state.

Dark sub pixel defects are best seen with solid bright patterns (white, yellow, green, or mid-grey).
Image of Dark sub-pixel.
Image of Dark sub-pixel.
Image of Dark sub-pixel.

Bright sub-pixels


Bright sub pixel failures occur when one or more sub pixels are locked into the on state. Combinations of multiple on pixels appear as other colors (e.g., full red + full green + full blue = white).

Bright sub pixel defects are best seen with solid dark patterns (black, red, or blue).
Image of Bright sub-pixels.
Image of Bright sub-pixels.

Partial sub-pixels


Partial sub pixel failures occur when sub pixels fail to turn all the way on or off.

This type of defect is best observed with solid patterns (black, white, red, green, blue, and mid-grey).

The white regions in the illustration are for demonstration purposes only. Real life partial sub pixel failures vary in colors and intensity.
Image of Partial sub-pixels.

Smudges


Smudges are stains or irregular shapes. The area affected by a smudge displays a slight change in luminance, appearing slightly dimmer or brighter than the background pattern. The cause of these smudges can either be contamination or damage to the front polarizer.

Smudges are best observed with a solid mid-grey pattern but are not limited to mid-grey. All solid patterns should be tested.
Images of smudge.

Buffing


Buffing is external damage to the front polarizer, often caused by contact with keycaps.
  • This type of defect is best observed with a solid black pattern displayed on the panel at full panel brightness.
  • Buffing can also be seen when the panel is not turned on.

Image of buffing.
Image of buffing.


Bright vertical line


A bright vertical line is a complete vertical line of sub pixels stuck on regardless of the active background pattern.
  • Bright vertical line defects are best observed on a solid dark pattern (black, red, green, and blue).
  • Using a white pattern for bright vertical line defect detection is not encouraged.

Image of Bright vertical line.
Image of Bright vertical line.
Image of Bright vertical line.


Dim vertical line


A dim vertical line is a complete vertical line of sub pixels stuck off regardless of the active background pattern.
  • Dim vertical line defects are best observed on solid patterns (white, black, red, green, blue, and mid-grey).
  • Use of a solid black pattern for dim vertical line detection is not encouraged.

Image of dimm line.
Image of dimm line.
Image of dimm line.


Partial bright vertical line


Partial vertical lines are caused by an open drain or a shorted data line.

This type of defect is best observed on solid patterns (white, red, green, blue, and mid-grey).
Image of Partial bright vertical line.
Image of Partial bright vertical line.
Image of Partial bright vertical line.

Data to common short


A data to common short defect results in a vertical bright line greater than one sub pixel wide but less than an entire driver IC block of data. The line is caused by a data line shorted to the common.

This type of defect is best observed on a full black pattern.
Image of Data to common short.
Image of Data to common short.
Image of Data to common short.

Vertical block defect


A vertical block defect is caused by an entire source (column) column driver(s) failure.
Image of Block defect.
Image of Even block defect.

Bright horizontal line


A bright horizontal line is a complete bright horizontal line of sub pixels stuck in the on condition regardless of the active background pattern. The horizontal line can be red, green, or blue.
Image of Bright horizontal line
Image of Bright horizontal line
Image of Bright horizontal line

Horizontal block


A horizontal block defect occurs when an entire gate is not functioning. One or more thick white bands span the entire LCD screen.

Horizontal block defects are best observed with a full dark pattern (black, red, green, or blue) and the inverter set at maximum brightness.
Image of horizontal block image.
Image of horizontal block image.

Residual image


A residual image defect is the remnant of a video image onscreen after it has been removed electronically. It is generally most pronounced for cases where the image was unchanged for long periods of time and/or had high contrast.

Residual images are best observed with a solid mid-grey pattern.
Image of Residual image.
Image of Residual image.

Pooling


Pooling defects are observed as ring-like waves or a rippling effect of the liquid crystal material. Pooling appears similar to a Newton ring but is temporary. Over time pooling dissipates.

LCD panels commonly pool when the display or system is moved, but the disturbance should cease over a very short time. Keep in mind that the L in LCD stands for liquid.

When observing a rippling defect, keep in mind the following:
  • If the rings dissipate, then the defect is pooling.
  • If the rings do not dissipate, then the defect is Newton rings.

Image of pooling.


Newton ring


A Newton ring is a ring-like panel disturbance that is permanent. Unlike pooling defects, a Newton ring defect does not dissipate over time.

When observing a rippling defect, keep in mind the following:
  • If the rings dissipate, then the defect is pooling.
  • If the rings do not dissipate, then the defect is Newton rings.

Image of Newton ring.


Backlight


A backlight defect occurs when the LCD panel remains blank after the system has powered on. No light is visible and some video graphics and/or text may barely be visible on the screen.
Image of backlight.
Image of backlight.
Image of backlight.

Light leakage


Light leakage is observed as dim light that is visible from behind the LCD bezel that leaks onto the screen. The effect is very disturbing to customers while watching DVD movies in a dark place such as on an airplane at night because DVD movies have large black bars at the top and bottom of screen that exaggerate this type of defect.
  • Light leakage is not limited to the area near the CCFL; it can appear anywhere around the peripheral of the LCD bezel.
  • Test for light leakage in a dark room with the panel displaying a solid black pattern and with the inverter set at maximum brightness.

Image of light leakage.
Image of light leakage.


Glass crack or fracture

A glass crack or fracture is caused by the LCD panel being placed under stress or suffering a shock beyond its tolerable limit. Cracks or fractures are permanent and irreparable.
Image of glass.

Crosstalk

Crosstalk defects are shadows or a gray effect that appears vertically or horizontally from the image.
Image of crosstalk.
Image of crosstalk.

A good resource for information on LCD’s is going directly to the most common manufacture like ScreenTek, Ltd - URL: http://www.screentekinc.com/

If you have any negative/positive feedback that you would like to share, regarding any data recovery company, please feel free to email me at Articles@McClainSolutions.com
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