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New IPS Technologies - Introduction
There used to be a time
when manufacturers and customers were just happy to know their screen was using
an IPS (In Plane Switching) panel. Now it seems there's all kinds of different
versions cropping up, with new names and apparently different characteristics. I
wanted to discuss the different versions being used and promoted today, and
hopefully help summarise some of the differences.
What do LG.Display Have to Say About It?
Firstly, most IPS panels
are manufactured by
LG.Display, previously known as LG.Phillips. It's interesting to note that
within their websites
technical FAQ section they make reference to the different naming schemes
being used to identify IPS panels. This is copied from their website so excuse
the slightly odd English:
[IPS
vs IPS-α] Is
there any product difference between IPS and IPS-α
?
Physically, there
exits no difference between IPS and IPS-α.
However, Dell or HP, indicates “Intel Inside” in their products all the same
time, even though they possess unique properties of product. Like this, we will
keep on promoting the product indicating IPS, where several companies using IPS
indicate IPS Premium to emphasize each appealing point.
So they use the term IPS-α
to give a blanket reference to all the different types of IPS panel being
mentioned (although they substitue the 'α'
for an 'a' in parts of it). They are saying really that they aren't too
concerned by it, the panels are all IPS, and different manufacturers use their
panels and just highlight the strengths or features they want by adding another
letter. This seems to fit in with some of the more recent versions being
promoted, which we discuss below.
What Are the Different Versions?
-
IPS
- IPS stands for 'In Plane Switching' which was originally developed by
Hitachi in 1996. This original version had some obvious limitations and has
been through several generations sinces its initial development. It was
produced to combat the two main issues with TN matrices, those being limited
viewing angles and low-quality colour reproduction. As already stated, the
main manufacturer of IPS technology today is LG.Display (prev LG.Philips)
-
S-IPS
- 'Super IPS' was the first major development in IPS technology, helping to
overcome some of the original drawbacks and now offering some improved
response times and lower production costs. You will still see S-IPS mentioned
in modern displays (e.g. HP still refer to their
LP2475W as having an S-IPS panel on their website) and LG.Display still
refer to their technology as S-IPS on their website in many cases. This is
probably still the most generic name used for IPS panels in the market.
-
AS-IPS
- 'Advanced Super IPS' hasn't really been seen much, but was used by NEC to
promote their
NEC 20WGX2 when it was launched. This was supposedly a custom made and
tweaked panel produced by LG.Display exclusively for the 20WGX2, and it was
characterised by an excellent response time, something which was really a
first in the IPS market.
Above: NEC
20WGX2
-
H-IPS
- A newer generation of S-IPS panels, this time with a slightly different
pixel alignment and setup giving rise to the name 'Horizontal IPS'. Pixels
are orientated in straight vertical lines with a slightly smaller electrode
width. Close inspection of modern IPS panels can show this new H-IPS pixel
structure, although not all manufacturers refer to their models as featuring
an H-IPS panel. Indeed, LG.Display don't really make reference to this H-IPS
version, although from a technical point of view, most modern IPS panels are
H-IPS in format. NEC have referred to H-IPS in their recent panel specs for
models such as the 2690WXUi2 and 3090WUXi.
-
e-IPS
- This is perhaps the most confusing of the 'new' versions of IPS panel being
used today. It's not really been clarified, and the 'e' seems to be a bit of a
mystery. Back in 2005, LG.Display talked about the improvements they were
making with their latest generation of 'Enhanced IPS' panels , mostly relating
to the overdriving circuitry they were now using to boost response times. This
was some time ago, and the name e-IPS (or should that have been E-IPS?) was
never really widely used. We saw the AS-IPS panel in the NEC 20WGX2 which
seemed to be offering the same improvements, and then H-IPS became more of a
widespread name for the newer generation of panels. These new H-IPS
panels featured fast response times and the presence of RTC, so perhaps
LG.Display didn't bother with the E-IPS name too much.
Above:
Dell 2209WA
More recently though,
the
Dell 2209WA was the first IPS-based model to be released in the 22" market
and advertised as featuring an e-IPS panel. The very competitive and low cost
lead some to speculate that the 'e' stood for 'economy IPS'. There seems to
have been a fair amount of use of this new 'e-IPS' name with other
manufacturers such as NEC using it in their specifications for their
new 2490WUXi2 for instance. They have even made the distinction and used H-IPS
in other models in their range (e.g. 2690WUXi2).
The name 'economic IPS' seems to make the most sense, although it could also
be linked to 'enhanced' and perhaps even 'energy efficient' or 'eco' with all
the modern focus on carbon footprints and power consumption. It is a
sub-section of H-IPS panels really but used in lower cost displays as these
panels are less expensive to manufacturer.
Some are actually 6-bit + AFRC modules in fact (as opposed to true 8-bit)
which might explain how the costs are kept very low in some cases.
-
UH-IPS and H2-IPS -
These are new names which some manufacturers such as HP and LG seem to be touting a little.
They has been mentioned with the launch of the HP ZR24w and ZR22w models
for instance, along with LG's line of IPS LED screens (e.g. IPS226V). HP have stated
that these 'new' panels offer improved energy efficiency, but it's unclear
what the new letters stand for. Perhaps the 'UH-IPS' stands for 'Ultra
Horizontal-IPS'? It certainly seems these are just slightly updated versions
of H-IPS panels, with HP playing on a certain key message or characteristic
with their description. It's possible as well that UH-IPS is just the same
thing as e-IPS, with different manufacturers using different terminology to
try and separate their displays. I suspect that UH-IPS is either the same
thing as e-IPS, or a sub-category of that development, which in turn is a
sub-category of H-IPS.
Some spec sheets from LG give some clues as to the differences.
The lines separating the
subpixels are smaller than with H-IPS and therefore the UH-IPS technology has
an 18% higher aperture ratio. This will supposedly improve brightess and
enhance contrast, all while allowing them to save energy. LG have used this
terminology with their LED backlght models.
-
S-IPS II - Another new term being used by
LG for some of their modern IPS LED screens such as the IPS236V. This "S-IPS
II" reportedly has an even higher aperture ratio than UH-IPS (11.6% higher),
further improving brightness and contrast and helping save energy. This
particular IPS236V is again combined with LED backlighting. It looks also from
the information available (above) that the pixel structure has been altered
and is no longer vertical as with H-IPS, but more like the traditional S-IPS /
AS-IPS "arrow" layout. This looks more like an e-IPS type development, but
returning to the older S-IPS pixel layout as opposed to developing H-IPS.
-
p-IPS
-
This is a new name which NEC have
started to talk about since early 2010 with their
new PA series of screens. Thankfully they've been kind enough to tell us
what the 'p' stands for in their marketing, giving rise to the generation of
'Performance IPS' panels. This new panel name is being used in the new 24" -
30" sized screens (PA241W, PA271W and PA301W). In fact the p-IPS name is just
a sub-category of H-IPS technology, being created as a way for NEC to
distinguish their new "10-bit" models from the rest of their range. In
addition, when you look into the details of it the panels are actually an
8-bit module with 10-bit reciever, giving you an 8-bit+AFRC module. This is
capable of producing a 1.07 billion colour palette (10-bit) through FRC
technology but it is not a true 10-bit colour depth.
There are very few true 10-bit panels out
there in the market, although a 24" 10-bit module was features in the HP
LP2480zx for instance, but at a much higher cost. Some other high end models
use true 10-bit panels as well, but you need to be a little wary of
manufacturers specified 10-bit figures as they are not always 100% accurate.
It's all very well saying a panel is capable of
10-bit colour depth (1.07 billion colour palette) as opposed to an 8-bit
colour depth (16.7 million colours), but you need to take into account whether
this is practically useable and whether you're ever going to truly use
that colour depth. Apart from the requirements of your application, operating
system, graphics card and software, one more pertinent limitation is from a
display point of view, where there must be an interface which can support
10-bit colour depth. At the moment DisplayPort and Dual-link DVI are the only
options which can. A full 10-bit work flow is still extremely uncommon in the
current market.
Regardless of whether you have a true
10-bit colour depth being displayed, a screen with 10-bit capabilities still
has its advantages. The monitor should still be capable of scaling the colours
well, even from 24-bit sources. Most of these 10-bit panels will also be
coupled with extended internal processing which will help improve accuracy and
these are better translated onto a 10-bit panel than they would be onto an
8-bit panel, giving less deviation and less chance of banding issues.
Asus have also adopted the "p-IPS" name in their
recent 24"
PA246Q model, which again is an IPS based screen with "10-bit" colour
support. It is not only NEC who are using this new name to distinguish the
models using these new panels. Some manufacturers have utlised the same 10-bit
panels in their screens but have not used the p-IPS name, and stuck with IPS
or sometimes S-IPS instead (e.g. Dell U2410, U2711, U3011).
Above: NEC P241W
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