Thin film transistor liquid crystal display (TFT-LCD) is a variant ofliquid crystal display (LCD) which uses thin-film transistor(TFT) technology to improve image quality (e.g., addressability, contrast). TFT LCD is one type ofactive matrixLCD, though all LCD-screens are based on TFT active matrix addressing. TFT LCDs are used in television sets, computer monitors, mobile phones, handheld video game systems, personal digital assistants, navigation systems, projectors, etc. [1] Contents [hide]1 Construction2 Typeso2.1 Twisted nematic (TN) o2.2 In-plane switching (IPS) o2.3 Advanced fringe field switching (AFFS) o2.4 Multi-domain vertical alignment ( MVA) o2.5 Patterned vertical alignment (PVA) o2.6 Advanced super view (ASV) 3 Display industry4 Electrical interface 5 Safetyo5.1 Toxicity6 See also7 References8 External links[ edit ]Construction
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8/6/2019 Thin Film Transistor Liquid Crystal Display
improvements to these shortcomings. Because of its wide viewing
angle and accurate color reproduction (with almost no off-angle color
shift), IPS is widely employed in high-end monitors aimed at
professional graphic artists, although with the recent fall in price it has
been seen in the mainstream mar et as well.
Hitachi IPS evolving technology[8]
Name Nickname Year AdvantageTransmittance/contrast ratio
Remarks
Super TFT IPS 1996 Wideviewingangle
100/100 Base level
Most panels also support true 8-bit per channel color . These improvements came at the cost of a slower response time, initially about 50 ms. IPS panels were also
extremely expensive.
Super-IPS S-IPS 1998 Color shiftfree
100/137
IPS has since been superseded by S-IPS (Super-IPS, Hitachi Ltd. in 1998), which has all the benefits of IPS technology with the addition of improved pixel
refresh timing.
AdvancedSuper-IPS
AS-IPS 2002 Hightransmittance
130/250
AS-IPS, also developed by Hitachi Ltd. in 2002, improvessubstantially on the contrast ratio of traditional S -IPS
panels to the point where they are second only to some S-PVAs.
IPS-Provectus
IPS-Pro 2004 High contrastratio
137/313
The latest panel from IPS Alpha Technology with a wider
color gamut and contrast ratio matching PVA and ASVdisplays without off-angle glowing.
IPS alpha IPS-Pro 2008 High contrastratio
Next generation of IPS-Pro
IPS alphanext gen
IPS-Pro 2010 High contrastratio
Technology transfer from Hitachi to Panasonic
LG IPS evolving technology
Name Nickname Year Remarks
Super-IPS S-IPS 2001 LG Display remains as one of the main manufacturers of panels based on HitachiSuper-IPS.
8/6/2019 Thin Film Transistor Liquid Crystal Display
TFT stands for Thin-Film Transistor. TFT technology is a new standard these days for
manufacturing displays, monitors, laptop screens, and other devices. TFT LCD displays can
show crisp text, vivid colors, fast animations, and complex graphics.
TFT LCD monitors, also called flat panel displays, are replacing the old style cathode ray
tubes (CRTs) as the displays of choice. Almost all LCD monitors today take advantage of the TFT technology.
What are the benefits of a TFT display?
Each pixel on a TFT display is backed by a tiny transistor. Transistors are so small these
days, they need only a very minimal charge to control what they do. TFT displays are much
more energy eff icient than regular CRT screens that need a powerful light source.
TFT displays also allow for very f ast re-drawing of the display, so the image has very
little chance to flicker. This was not always the case with flat-panel monitors. Original
passive matrix LCD displays were not able to refresh at very high rates and therefore could
not keep up with fast moving images. A TFT monitor refresh rate is very high resulting in a
display that can be used for video, gaming, and all forms of multimedia.
A TFT monitor delivers crisp text, vibrant colors , and an improved response time for
multimedia applications. Today's standard for response rate in TFT monitors is 16 ms or
less.
H ow does TFT display work?
Let us start with explanation how a LCD display, a predecessor to TFT LCD, works.
In general, a LCD display comprises of a layer of LCD material and one or more polarizinglayers made of plastic, glass, or some other material. A LCD display has a sandwich-like
structure with liquid crystals filled between two glass (or plastic or polycarbonate) plates.
A LCD display shows a picture through millions of tiny picture elements called pixels. You
can understand a pixel as a tiny dot on your screen.
Pixels are formed by liquid-crystal cells that change the direction of light passing through
them in response to an electrical voltage.
These liquid crystals when stimulated by an external electrical charge can change the
properties of light passing through them. When you align two polarizing materials witheach other, light passes through. When you align one polarizing agent at a 90° angle to the
other, light is blocked. Change the voltage, and the amount of light passing through the
display is changed.
8/6/2019 Thin Film Transistor Liquid Crystal Display
Liquid crystals in LCD monitor act as a dynamic polarizing agent. They change their
orientation when you place a voltage across an LCD cell. The orientation of the polarizing
agent under the LCD layer either blocks or pass es light.
So, where does a TFT come into the game?
A TFT display is an advanced LCD display. A TFT monitor uses so -called thin-f ilm
transistortechnology to project a picture on the screen. Transistors in a TFT display are
used to change the orientation of the polarizing agent. A typical 17-inch TFT monitor has
about 1.3 million pixels and 1.3 million transistors. The following text explains TFT in a
greater detail...
Active or passive LCD?
When you look at a passive-LCD technology, the cells act as capacitors. When you charge acell, the liquid crystal flips to one position. When you stop supplying charge to the cell, it
voluntarily bleeds off its voltage and the liquid crystal slowly twists back to its original
position.
Passive LCD panels cannot quickly change the orientation of the crystal. Well, it is quick,
but not quick enough to display fast -moving graphics. To overcome this slowness,
engineers came up with active-LCD technology. Active-LCD displays use transistors to
actively change the orientation of crystals. That is where TFT comes from. T in TFT for
transistor. This method allows for faster control of the LCD cell but is also more complex.
8/6/2019 Thin Film Transistor Liquid Crystal Display
Quite a lot of our customers these days go for TFT monitors when they buy their computers. Most
buy their TFTs because they look better than CRT monitors and because the price differentials are
much lower than what they used to be. We try our best to convey to our customers the differences
between CRTs and TFTs and the specific scenarios when one is better than the other. Some timeswe get through and some times we don't. Here we would like to bring out the differences between
the two types of monitors and their pros and cons.
Traditionally all computer monitors used to be CRT monitors which are quite similar to the CRT
televisions we have in our homes. LCD monitors were only used with laptops as the price
differences were quite high. However as technology advanced and the price differences between
CRTs and TFTs came down it became viable to sell computers with TFT (or LCD) monitors. The
display device in a CRT monitor is a cathode ray tube which is inherently bulky and power-thirsty
whereas the display device in a TFT monitor is a flat array of Thin Film Transistors which makes
the TFT monitors much smaller in size and also less power consuming.
The major differences between the two are
1) CRT monitors are bulky and consume a lot of table space where as TFT monitors are thin and
occupy less space.
2) TFT monitors are more easy on the eyes of the viewer than CRT monitors.
3) CRT monitors have much much faster response times than TFT monitors. Response time is the
time interval taken by a pixel on the screen to transit from the on state to the off state or reverse.
4) TFT monitors consume less power than CRT monitors. A typical 15" CRT monitor consumesabout 100W of power whereas a corresponding TFT monitor would only consume 30W of power.
5) TFT monitors looks more elegant than CRT monitors.
6) CRT monitors tend to have much better color responses than TFT monitors. In other words CRT
monitors display colors much better than TFT monitors.
Based on the above differences we can easily make certain deductions about the scenario's where
each of these types of monitors are ideal.
1) You save 70W when you use a 15" TFT monitor instead of a 15" CRT monitor. This would
translate to around 1 unit of electricity every 14 hours of usage. So depending on your usage
patter you can see how long it would take to break even on the cost differential through energy
savings. Say 1 Unit of energy costs 8 Rupees (approx 20 cents) and the cost differential is Rs 4000
(approx 100$) and you use your monitor for 10 hours every day, you will break even in around
700 working days. The equation used is simple; No of days for breaking even = ((Cost
Differential/Cost per unit)*14)/(Hours used per day). Based on your usage pattern and your
budget you can use the above data to make an educated decision.
8/6/2019 Thin Film Transistor Liquid Crystal Display
2) If you are a graphics artist and you require close to realistic representation of colors you will
have to go for a CRT monitor irrespective of any other factors.
3) If you are a gamer then depending on the type of games you play you will have to choose
between CRT and TFT monitors. If you play very fast moving games then response times of the
monitors comes into play and you might end up having to buy a CRT monitor to get a smoothgaming experience. If however you play more strategy games than action or racing games then
depending your other usage patterns you can decide between either a TFT or a CRT.
4) If you have to move your residence frequently as part of your job and you have to have a
desktop, then a TFT monitor would make more sense. It should be noted that a laptop would make
even more sense in such cases.
5) If you are running a software development center it might be wiser to select TFTs for your
software developers and CRTs for your graphics guys. If you are running any other kind of office
where your computers remain on most of the day then TFTs would pay for themselves in a few
years and would be the ideal choice.
6) If you are running a retail outlet a TFT would give your POS counter a more professional look
and also help you save on your electricity bills.
7) Small or restricted work areas also place a default preference of TFT monitors over CRT
monitors.
If you need help in deciding between a TFT monitor or a CRT monitor, do get in touch with us
using the comments form below and we will try to help you in making your decision.
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A: Short for Thin Film Transistor, a type of LCD flat-panel display screen, in which each pixel is
controlled by from one to four transistors. TFT screens are sometimes called active-matrix LCDs.
Q: What are the benefits of a TFT display?
A: A TFT LCD display delivers crisp text, vibrant color and an improved response time for visual
applications at the best resolution of all the flat-panel techniques, but it is also the most expensive.
Q: What sets the TFT apart for other LCDs?
A: TFT displays use a separate tiny transistor for each pixel on the display. Because each transistor is so
small, the amount of charge needed to control it is also small. This allows for very fast re-drawing of the
display, as the image is re-painted or refreshed several times per second.
Q: What are the differences between TFT and Color STN?
A: TFT displays utilize active matrix technology and feature transistors on every pixel. Color STN (CSTN)
is a passive matrix graphic LCD with a color filter. It only has one transistor per each pixel row and
column and features a lower refresh rate than TFTs.
Q: What size TFTs does Microtips currently offer?
A: We currently offer a 2.4´, 2.8´, 3.5´, 4.3´, 5.7´ and 7.0´ TFT.
Q: How do I interface with a TFT?
A: 1st Pick a microprocessor with a built-in TFT controller (this will tell you which interface type to use)
2nd Determine which TFT size and interface type required
3rd Determine how the pins on the TFT should best connect to the corresponding pins on the your
microprocessor
4th Connect the FFC from the TFT to a mating connector mounted on your board which is assigned to
the TFT interface of the microprocessor
5th Write initialization code and software through your microprocessor to the TFT
Q: How does Microtips handle a fluctuating TFT supply chain? A: Microtips utilizes strategic partnerships with our supply chain and focuses on standard TFT sizes
(3.5´, 5.7´, and 7.0´).
Q: Who drives the TFT market?
A: The small TFT displays below 3.5´ are typically driven by the large volume cell phone manufacturers
in Asia. That being said the supply chain for TFT displays below 3.5´ can be more volatile than the 3.5´
and above sizes. The digital photo frame industry has also begun to affect the availability of the 7.0´ and