Transcript Computer Peripherals - Kevin Fitzgerald.net

Computer Peripherals
“It's been said that a million monkeys typing on a
million keyboards would reproduce the works of
Shakespeare. Thanks to the Internet, we now
know that is incorrect.”
-unknown
Computer Peripherals
VIDEO MONITORS
Cathode Ray Tube
1. Construction
Cathode Ray Tube
2. Operation
Cathode Ray Tube
3. Software concerns

Random Access Memory Digital-Analog
Converter (RAMDAC)

Vertical Sync

Rasterization (aliasing)
Cathode Ray Tube
Pros

Responsiveness
Cons

Size

Heat

Vertical refresh rates
(vs. LCD)






Price
No Dead Pixels
High contrast ratio
Higher brightness
No Native Resolution
Virtually no viewing
angle
cause ‘flicker’
Liquid Crystal Displays
Thin flat displays
 Color or Monochrome
 Made up of segments or arrays
 Low power draw
 Used often in portable or battery
operated devices because of low power
consumtion

Example of a monochrome segmented display
LCD History
Otto Lehmann
publishes his work
"Liquid Crystals".
1888
The Marconi Wireless
Telegraph company
patents the first practical
application of the
technology, "The Liquid
Crystal Light Valve".
1911
1904
Friedrich
Reinitzer
discovers the
liquid crystalline
nature of
cholesterol
extracted from
carrots
1936
Charles Mauguin
describes the
structure and
properties of liquid
crystals.
In the fall, George H. Heilmeier, then working in the RCA
laboratories on the effect discovered by Williams realized the
switching of colors by field-induced realignment of dichroic dyes in
a homeotropically oriented liquid crystal. Practical problems with
this new electro-optical effect made Heilmeier to continue work on
scattering effects in liquid crystals and finally the realization of the
first operational liquid crystal display based on what he called the
dynamic scattering mode (DSM). Application of a voltage to a DSM
display switches the initially clear transparent liquid crystal layer
into a milky turbid state. DSM displays could be operated in
transmissive and in reflective mode but they required a
considerable current to flow for their operation
The first active-matrix liquid crystal
display panel was produced in the
United States by T. Peter Brody
1964
1962
The first major English language
publication on the subject
"Molecular Structure and Properties
of Liquid Crystals", by Dr. George
W. Gray
•
Richard Williams of RCA found that
liquid crystals had some interesting
electro-optic characteristics and he
realized an electro-optical effect by
generating stripe-patterns in a thin
layer of liquid crystal material by the
application of a voltage. This effect
is based on an electrohydrodynamic instability forming
what is now called “Williams
domains” inside the liquid crystal
•
1972
1970
The twisted nematic field effect in
liquid crystals was filed for patent by
Hoffmann-LaRoche in Switzerland
•
•
Produced displays for wrist watches
2008
LCD TVs are the main
stream with 50% market
share of the 200 million
TVs forecasted to ship
globally in 2008
according to Display
Bank
Overview – TN (Twisted Nematic)
1. Polarizing filter film with a vertical axis
to polarize light as it enters.
2. Glass substrate with ITO electrodes.
The shapes of these electrodes will
determine the dark shapes that will
appear when the LCD is turned on or off.
Vertical ridges etched on the surface are
smooth.
3. Twisted nematic liquid crystals.
4. Glass substrate with common
electrode film (ITO) with horizontal ridges
to line up with the horizontal filter.
5. Polarizing filter film with a horizontal
axis to block/pass light.
6. Reflective surface to send light back
to viewer. (In a backlit LCD, this layer is
replaced with a light source.)
With the top polarizer
removed and set on top
With the top polarizer
removed and aligned parallel
to the bottom polarizer
LCD Terms

Resolution:

Dot pitch:

Viewable size:

Response time:

Refresh rate:



Matrix type:
Viewing angle:
Color support:

Brightness:



Contrast ratio:
Aspect ratio:
Input ports:
The horizontal and vertical size expressed in pixels (e.g., 1024x768). Unlike CRT
monitors, LCD monitors have a native-supported resolution for best display effect.
The distance between the centers of two adjacent pixels. The smaller the dot pitch
size, the less granularity is present, resulting in a sharper image. Dot pitch may be
the same both vertically and horizontally, or different (less common).
The size of an LCD panel measured on the diagonal (more specifically known as
active display area).
The minimum time necessary to change a pixel's color or brightness. Response time
is also divided into rise and fall time. For LCD Monitors, this is measured in btb
(black to black) or gtg (gray to gray). These different types of measurements make
comparison difficult.
The number of times per second in which the monitor draws the data it is being
given. A refresh rate that is too low can cause flickering and will be more noticeable
on larger monitors. Many high-end LCD televisions now have a 120 Hz refresh rate
(current and former NTSC countries only). This allows for less distortion when
movies filmed at 24 frames per second (fps) are viewed due to the elimination of
telecine (3:2 pulldown). The rate of 120 was chosen as the least common multiple of
24 fps (cinema) and 30 fps (TV).
Active or Passive.
The angle the display is completely readable
How many types of colors are supported (coll., more specifically known as color
gamut).
The amount of light emitted from the display (coll., more specifically known as
luminance).
The ratio of the intensity of the brightest bright to the darkest dark.
The ratio of the width to the height (for example, 4:3 (square), 16:9 or 16:10 (wide)).
Types include DVI, VGA etc.
Color LCDs

Active Matrix for high
pixel counts and highresoultion displays



Multiple types
Passive matrix for small
amount of segments
(e.g. watches, alarm
clocks, microwaves..
Etc)
Position of the pixels
produces different
methods to produce
images (see images)
Cutting Edge and Beyond

Organic Light
Emitting Diode
(OLED)
Cutting Edge and Beyond

OLED

E-Paper
Cutting Edge and Beyond

OLED

E-Paper

Holographic