HP w15e Understanding pixel defects in TFT flat panel monitors
HP w15e - Widescreen LCD Monitor Manual
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- HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 1
defects in LCD monitors Bob Myers Displays Business Unit Last revised: July 1, 2009 Introduction...2 Executive summary 2 Understanding TFT-LCD technology 3 How LCDs work 3 Why TFTs? ...3 Understanding pixel defects 4 How pixel defects occur 4 How to spot a sub-pixel defect 5 HP pixel-defect - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 2
do they work? A detailed look will show that millions of tiny sub-pixels cover the typical flat panel screen, producing the mixture of color and detail that forms the sharp, vibrant images flat panel users have come to expect. How do pixel and sub-pixel defects occur? The HP specification does not - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 3
a type of liquid crystal display (LCD), also known as an active-matrix LCD (AMLCD), used in all HP LCD monitors as well as HP iPAQ devices and HP notebook displays. To understand how pixel defects occur, it helps to understand the technology behind this type of LCD. How LCDs work A liquid crystal is - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 4
switch very quickly, and then hold the state of the sub-pixel while the panel drivers take care of the other rows and columns of the display. This results in a great improvement in the contrast and response time possible with LCD technology, and permits the manufacture of largesize, high-resolution - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 5
are not likely to encounter this situation. To locate defective sub-pixels, the monitor should be viewed under normal operating conditions, in normal operating mode at a supported resolution and refresh rate, from a distance of approximately 20 inches (51 cm). The following standards show the - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 6
sub-pixels stuck on or off The HP specification ensures that all of our products exceed the ISO Class 2 requirements, as no full pixel defects are ever permitted; in most cases, HP displays will meet the more stringent Class 1 specification. As mentioned earlier, the HP specifications dictate no - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 7
defects, and no sub-pixel defects spaced closer than 15 mm, with a maximum of five total sub-pixel defects. Figure 2. Pixel fault definitions. 7 - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 8
dark dot: A sub-pixel stuck on or off. Bright spots/lines: Spots or lines that appear light in the display. Defects do not vary in pixels. Rubbing line/defects: Horizontal or diagonal lines that appear gray with the display patterns dark and may have resulted from an "out of control" rubbing process - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 9
defect specifications are part of HP's ongoing effort to provide high quality products. When it comes to LCD-TFT displays, fewer pixel defects mean better quality. HP quality and reliability HP prides itself on a reputation for industry-standard best-of-breed products-and our line of LCD monitors is - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 10
HP LCD monitors include advanced power HP support umbrella, which includes 65,000 sales and service professionals in 160 countries around the world who provide an impressive depth of service and support at the local level. All HP LCD monitors come with a three-year limited global warranty on parts - HP w15e | Understanding pixel defects in TFT flat panel monitors - Page 11
HP sales office nearest you, please refer to your local phone directory, or call the HP Ltd. 19/F, Cityplaza HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP
1
Understanding pixel
defects in LCD
monitors
Bob Myers
Displays Business Unit
Last revised: July 1, 2009
Introduction
.........................................................................................................
2
Executive summary
.............................................................................................
2
Understanding TFT-LCD technology
......................................................................
3
How LCDs work
..............................................................................................
3
Why TFTs?
......................................................................................................
3
Understanding pixel defects
.................................................................................
4
How pixel defects occur
...................................................................................
4
How to spot a sub-pixel defect
........................................................................
5
HP pixel-defect standards
....................................................................................
5
HP specifications
.............................................................................................
5
International standards (ISO-9241)
..................................................................
6
Defect type definitions
.....................................................................................
8
The HP advantage
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9
HP quality and reliability
.................................................................................
9
Designed with the environment in mind
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9
HP service and support
..................................................................................
10
For more information
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11