Natural Opinions

An Archive Of My Thoughts

Acronyms

CRT:  Cathode ray tube
LCD:  Liquid crystal display
DLP:  Digital light processor
LCoS:  Liquid crystal on silicon
OLED:  Future, organic light emitting diode
CCFL-LCD:  Cold Cathode Fluorescent Light (this refers to the type of backlight used) - Liquid Crystal Display
LED-LCD:  Light Emitting Diode (this refers to the type of backlight used) - Liquid Crystal Display

CRT

Pros
-Superior color depth and accuracy
-Superior contrast, true blacks
-Better viewing angles
-Extremely low response times, no motion blur (unless it's part of the source) and less juddering
-Multiple native resolutions, it will look sharp with any of them
-Higher refresh rates
-Lowest possible input lag
-Extremely long lifespans
-No stuck/dead pixels
-Highly adjustable image properties such as contrast
-Even cheap models were capable of insane resolutions (only computer monitors, most TV models are SD)

Cons
-Flicker.  The higher the refresh rate the less noticeable it is.
-High frequency noise.  Particularly in lower end models due to the horizontal scanning causing magnetic parts to vibrate in the 15-20 KHz range.  The sound is very annoying but luckily many older people will not be able to hear these frequencies due to deteriorated hearing.  Increasing resolution and refresh rate will increase the scanning frequency and should thus make the noise less noticeable after a certain point.  This is far more likely to be noticeable in TVs than monitors.
-Size
-Weight
-Power consumption
-Heat
-Inferior brightness.  This can be a problem in brighter environments.
-Eye strain.  Decreases as refresh rate is increased.
-Burn in
-Less sharp compared to an LCD running at it's native resolution.  In lower end models the difference in sharpness can be very substantial.
-Analogue or mixed only, inferior signal transmission, no digital "enhancements" like frame interpolation
-Small size only
-Becomes "duller" over time as they age.  Maximum sharpness and brightness both decrease over time.
-Very few widescreen models available.  The geometry is difficult to handle.
-Most TV models are SD.  This is because the limitations on scanning speed make having a large screen space and high resolution at the same time very difficult.  HD CRTs were often small or had to resort to extremely expensive electronics or rear projection techniques.  Rear projection units are enormous, extremely heavy, extremely expensive, and have a number of other problems.
-Most are not flatscreen.  Geometry problems exist in both flatscreen and curved screen models.
-Most TV models were interlaced (most computer monitors support high resolution and progressive scanning) due to limit
-Overscanning is generally worse
-Limited inputs/outputs
-Reflective surface

Plasma

Pros
-Contrast is better than an LCD but worse than a CRT, close to true blacks
-Color depth and accuracy is better than an LCD but worse than a CRT
-Viewing angles are as good as a CRT
-Motion blur is almost as good as a CRT, judder is as good as a CRT
-Highest refresh rates of any type of common display system
-Long lifespans, almost as long as a CRT
-Image properties are more adjustable than an LCD but less adjustable than a CRT
-Digital
-Widescreen
-Flatscreen
-High definition
-Progressive
-Large sizes available
-No overscanning
-Plenty of inputs/outputs


Cons
-Will only look really good at it's native resolution
-Input lag is similar to an LCD
-Dead/stuck pixels are possible but less likely than an LCD
-Smaller sizes are limited to low resolutions
-Only large models exist
-Eye strain is greater than an LCD but still nowhere near a CRT
-Size is more than an LCD but less than a CRT
-Weight is more than an LCD but less than a CRT
-Power consumption is much higher than either an LCD or CRT
-Heat is higher than an LCD or CRT
-Inferior brightness to an LCD
-Burn in
-Becomes duller over time (lifespan is rated at about 100,000 hours average as I'm writing this in 2011)
-Reflective surface
-Does not function properly at high altitudes

LCD

Pros
-No flicker
-No high frequency noise
-Small size
-Light weight
-Low power consumption
-Less heat
-Capable of higher brightness
-Less eye strain
-No burn in
-Sharper than a CRT at it's native resoltuion
-Digital signals and digital enhancements like frame interpolation
-Available in a broad range of screen sizes
-Image not become duller as the display ages
-Widescreen models are widely availible
-Progressive, flatscreen, high definition
-Overscanning can be disabled
-Plenty of inputs/outputs
-Surface is not very reflective, it can be used in rooms with lots of light

Cons
-Inferior color depth and accuracy
-Inferior contrast, cannot produce true blacks
-Inferior viewing angles
-Higher response times, more motion blur and more judder
-Will only look sharp at it's native resolution
-Low refresh rates
-More input lag
-Shorter lifespans
-Can have stuck/dead pixels
-Very few options for true image adjustment, most options manipulate the image itself not how it displays it
-Were more expensive and higher resolution models cost a lot

Other Types

Rear projection
  -CRT
  -LCD (single chip)
  -LCD (three chip)
  -DLP (single chip)
  -Laser (Developed by Mitsubishi.  How it works is unknown)
  -LCoS

OLED
  -Future, organic light emitting diode

CCFL-LCD
Cold Cathode Fluorescent Light (this refers to the type of backlight used) - Liquid Crystal Display

LED-LCD
Light Emitting Diode (this refers to the type of backlight used) - Liquid Crystal Display

Home theater projectors
  -DLP (single chip)
  -DLP (three chip)
  -LCD (single chip)
  -LCD (three chip)
  -LCoS

How they work

-DLP (single chip)
  Uses a chip that is essentially an array of microscopic mirrors (one for each pixel) that can be in two positions, flat (pointing towards the screen), or pointing downwards (away from the screen).  This extremely small grid of micromirrors is called a DLP chip.  Images must be scaled to the displays resolution before they can be displayed.  They are then broken into 6 images each containing 1 of the 6 color components (red, green, blue, white, cyan, yellow).  A wheel of these 6 color filters is turned by a motor.  A lamp shines light through the color wheel as it rapidly moves between the 6 different colors.  The colored light hits the the mirrors which rapidly change direction.  When the mirrors are pointed downwards they direct the light away from the screen, when they are in the flat position they direct light towards the screen.  To control the brightness of each pixel for a given color component you use to mirrors to control how long the light is relfected at the screen.  This works because even though technically the pixels are turning on/off really quickly your brain averages it to create a "brightness" for that pixel.  For example if while in the red position the mirror was mostly in the off position your brain will perceive that pixel as having very little red in it.  If it was mostly in the on position your brain will perceive it as having a lot of red.  And likewise for all the other colors.  The processor in a DLP chip has to break the color components up even further into many subfields so that no single color stays on the screen for too long.  It also has to rapidly move the mirrors between on/off to control brightness instead of holding them in the on/off position for different lengths of time since the rapid change is needed to keep the brain from being able to focus on it and therefore break the color effect.  Finally the light from the mirrors passed through a magnifying lense to project it onto a big screen.  The color rapid switching between different colors being displayed using the color wheel sometimes causes a  "rainbow effect".

  -DLP (three chip)
  Instead of using a color wheel the light from the lamp passed through a prism that breaks it up into red/green/blue.  Each type of light is directed by a series of mirrors towards a different DLP chip.  So you have 3 DLP chips instead of one.  One for red, one for blue, and one for green.  The mirrors control the brightness of each pixel by changing between the on/off position rapidly just like before.  All three chips reflect the light into a combining filter, a special lens that combined the three light beams into one.  This color beam passed through a magnifying lens which projects it onto the screen.

  -LCD (single chip)
  The light from the lamp passing through liquid crystals.  The liquid crystals change the polarity of the light passing through them.  The light then passes through a polarity filter that blocks light of a certain polarity.  You can think of this almost like shutters being opened/closed to change the amount of light that can get past them.  There are 3 LCs (liquid crystals) for each pixel.  One has a red filter over it, one has a blue filter over it, and one has a green filter over it.  Then those three subpixels have a combining filter over them that combines the red/green/blue light for that pixel.  Finally the light from all of the pixels bounced off of a mirror into a magnifying lens that projects it onto the screen.

  -LCD (three chip)
  Works the same way except the light from the lamp passed through a prism that breaks it up into red/green/blue.  Each type of light is directed by a series of mirrors towards a different LC chip.  After the three LC chips control the amount of red/green/blue light that makes it through each pixel the three light beams each hit a mirror that bounces them into a combine filtter that combines them into a single beam.  This passes through a magnifying filter that projects it onto the screen.

  -LCoS
  The single LC chip lies on top of a plate of reflective silicon.  The color/combine filters are on the other side.  The lamp is aimed upwards towards the LC chip (about 45 degrees) so that the light from the lamp will come into the LC chip at an angle.  The light from the lamp passes through the LC chip and is reflected back out by the silicon on the other side.  That light then goes through a magnifying lens that projects it onto the screen.

  -Plasma
  Each pixel has three subpixels (red/green/blue) just like in an LCD and a combine filter on top of them to combine the red/green/blue light that comes out of them.  These subpixels are each a plasma cell.  A plasma cell has a small glass air tank filled with pressurized neon gas.  A high voltage current is applied to the gas which excited it, causing it to produce x-rays.  The x-rays hit a red, green, or blue phosphorous compound on the other side of the tank.  When the x-rays hit the phosphorous it excited the phosphorous, causing it to glow and produce red, green, or blue light.  This red/green/blue light passes into a combine filter for each pixel.  Plasma displays need to be large because of the amount of material needed to keep the pressurized gases in each cell contained.  Plasmas usually have a high reflective glass screen since the screen has to be strong enough to hold back the pressurized gases.  Although newer displays usually use much less reflective synthetic materials.  Since the phosphorus compounds slowly break down from the reaction the display becomes "duller" over time.  Plasmas made since 2006 tend to use compounds that decay much slower than than those made before 2006.