Philips 190E2FB/00 (AP), Service Manual

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18 190E2 LCD
FAQs (Frequently Asked Questions)
LCD Panel Technology
Q: What is a Liquid Crystal Display?
A:
A Liquid Crystal Display (LCD) is an optical device that is commonly
used to display ASCII characters and images on digital items such as
watches, calculators, portable game consoles, etc. LCD is the technology
used for displays in notebooks and other small computers. Like
light-emitting diode and gas-plasma technologies, LCD allows displays to
be much thinner than cathode ray tube (CRT) technology. LCD consumes
much less power than LED and gas-displays because it works on the
principle of blocking light rather than emitting it.
Q: What differentiates passive matrix LCDs from active matrix
LCDs?
A:
An LCD is made with either a passive matrix or an active matrix
display grid. An active matrix has a transistor located at each pixel
intersection, requiring less current to control the luminance of a pixel. For
this reason, the current in an active matrix display can be switched on
and off more frequently, improving the screen refresh time (your mouse
pointer will appear to move more smoothly across the screen, for
example). The passive matrix LCD has a grid of conductors with pixels
located at each intersection in the grid.
Q: What are the advantages of TFT LCD compared with CRT?
A:
In a CRT monitor, a gun shoots electrons and general light by colliding
polarized electrons on fluorescent glass. Therefore, CRT monitors
basically operate with an analog RGB signal. A TFT LCD monitor is a
device that displays an input image by operating a liquid crystal panel.
The TFT has a fundamentally different structure than a CRT: Each cell
has an active matrix structure and independent active elements. A TFT
LCD has two glass panels and the space between them is filled with liquid
crystal. When each cell is connected with electrodes and impressed with
voltage, the molecular structure of the liquid crystal is altered and controls
the amount of inlet lighting to display images. A TFT LCD has several
advantages over a CRT, since it can be very thin and no flickering occurs
because it does not use the scanning method.
Q: Why is vertical frequency of 60Hz optimal for an LCD monitor?
A:
Unlike a CRT monitor, the TFT LCD panel has a fixed resolution. For
example, an XGA monitor has 1024x3 (R, G, B) x 768 pixels and a higher
resolution may not be available without additional software processing.
The panel is designed to optimize the display for a 65MHz dot clock, one
of the standards for XGA displays. Since the vertical/horizontal frequency
for this dot clock is 60Hz/48kHz, the optimum frequency for this monitor is
60Hz.
Q: What kind of wide-angle technology is available? How does it
work?
A:
The TFT LCD panel is an element that controls/displays the inlet of a
backlight using the dual-refraction of a liquid crystal. Using the property
that the projection of inlet light refracts toward the major axis of the liquid
element, it controls the direction of inlet light and displays it. Since the
refraction ratio of inlet light on liquid crystal varies with the inlet angle of
the light, the viewing angle of a TFT is much narrower than that of a CRT.
Usually, the viewing angle refers to the point where the contrast ration is
10. Many ways to widen the viewing angle are currently being developed
and the most common approach is to use a wide viewing angle film,
which widens the viewing angle by varying the refraction ratio. IPS (In
Plane Switching) or MVA (Multi Vertical Aligned) is also used to give a
wider viewing angle.
Q: Why is there no flicker on an LCD Monitor?
A:
Technically speaking, LCDs do flicker, but the cause of the
phenomenon is different from that of a CRT monitor -- and it has no
impact of the ease of viewing. Flickering in an LCD monitor relates to
usually undetectable luminance caused by the difference between
positive and negative voltage. On the other hand, CRT flickering that can
irritate the human eye occurs when the on/off action of the fluorescent
object becomes visible. Since the reaction speed of liquid crystal in an
LCD panel is much slower, this troublesome form of flickering is not
present in an LCD display.
Q: Why is an LCD monitor virtually low of Electro Magnetic
Interference?
A:
Unlike a CRT, an LCD monitor does not have key parts that generate
Electro Magnetic Interference, especially magnetic fields. Also, since an
LCD display utilizes relatively low power, its power supply is extremely
quiet.
Ergonomics, Ecology and Safety Standards
Q: What is the CE mark?
A:
The CE (Conformité Européenne) mark is required to be displayed on
all regulated products offered for sale on the European market. This 'CE'
mark means that a product complies with the relevant European Directive.
A European Directive is a European 'Law' that relates to health, safety,
environment and consumer protection, much the same as the U.S.
National Electrical Code and UL Standards.
Q: Does the LCD monitor conform to general safety standards?
A:
Yes. Philips LCD monitors conform to the guidelines of TCO Displays
5.0 standards for the control of radiation, electromagnetic waves, energy
reduction, electrical safety in the work environment and recyclability. The
specification page provides detailed data on safety standards.
Q: After I change new PC, I found this information on screen, how
can I do?
A: Because you activate Theft Deterrence function in SmartControl II.
Please contact IT manager or Philips Service Center.