Back in 2010, we investigated panel switching in TVs. Six months down the line, it's time to take a step back, take stock and see where things stand with LCD and plasma TVs.
Published: January 23, 2011 12:56 PM
By Vincent Alzieu
Translated by: Catherine Barraclough
Panel switching is when manufacturers deliberately use different types of screen panel (the bit that actually displays the picture) in a TV sold under a specific product name. In other words, the internal components of a given product can vary in relation to what stock is available from suppliers, or even what price the panels are being sold at.


Valse des dalles


It's a bit like a car manufacturer using a different engine in some of its cars without letting customers know.

To try and keep panel quality consistent no matter which supplier they use, TV manufacturers define a set of 'product specifications', to which their supplies must stringently adhere. Panel manufacturers must therefore guarantee a certain level of responsiveness, contrast, colour reproduction, viewing angles, etc. This is supposed to ensure that panels from different sources remain very similar, if not identical, no matter which one is picked for use in the final product.

That's how it works in theory. However, in practice we've found it can be quite a different story.

Plasma vs LCD

Probably around 90% of the TVs currently on the market use some kind of LCD panel. Plasma screens are becoming much rarer these days. However, this type of screen seems to be handled better by manufacturers, and only LCD screens really seem to be subject to panel switching.

Compared with plasma screens, LCD panels are smaller, slimmer, more energy efficient and some are available with a matte finish. However, the growing popularity of LCD panels does come at a price, since manufacturers are having trouble making successful televisions in quantities large enough to keep retailers around the world well-stocked—they simply can't get hold of enough components. Therefore, manufacturers tell us, they have no choice but to guarantee a certain level of production by using several component sub-contractors instead of just one.

Which Manufacturers Switch Panels?

Unfortunately they all do! All LCD TV manufacturers admit that they have to secure back-up sources of panels in case supply from one panel maker dries up. However, the extent to which panel switching actually occurs varies from brand to brand.

StrikeItLuckyTV

Toshiba, Sharp and Loewe confirm that they use panels from different sources in order to guarantee supply for all their retailers.

Panasonic has switched panels in the past but claims it will be able to stop doing so in 2011 thanks to the opening of its new panel factories.

Samsung said it would take great care in the future to make sure each panel supplier respects its product specifications. However, it has no intention to stop using different sources of panel for the time being.

Sony doesn't panel-switch much. It seems to do so more in its entry-level models than in its higher-end TVs.

LG and Philips are less affected because many of the TVs in their ranges are equipped with IPS panels that aren't manufactured by competitors. They therefore have to make the panels themselves. We think this is a very good thing and we'd like to see other manufacturers doing the same. However, panel switching still occurs in LG and Philips TVs that use TN or other kinds of panels.

To What Extent Does Panel Switching Occur? 51% at Samsung, 12% at Sony

A lack of time, means, and also collaboration from the interested parties, led us to focus our investigations on the LCD TV ranges of the two most popular TV brands on DigitalVersus in 2010: Samsung and Sony. Evidently, other manufacturers weren't exactly disappointed that we decided not to subject their TVs to the same treatment!Duel(2)

We looked at 84 different models from the Samsung 2010 TV range. With the help of our readers and certain retailers, we discovered that 41 TVs from this list were, in theory, not affected by panel switching. However, that means that 51% of the TVs were found to have panels from varying sources! The TVs that weren't exposed to panel switching tended to be higher-end models with PVA screens, as well as 37-inch models with MVA panels made by AU Optronics.

Thanks to one of our readers, who brought in his MVA-panel TV, we were able to compare two Samsung LE40C630 TVs against each other—one with a PVA panel and the other with an MVA panel. The differences were as obvious to us as they were to the TV's owner! In fact, the differences in colour, depth of black and viewing angles were very noticeable. This can be explained by the fact that our sensor picked up a 60% difference in contrast between the two screens, with the PVA panel at 4200:1 and the MVA at 2800:1.

Panel switching seemed to be less of a problem in the Sony TVs we looked at. Out of the 25 models from 2010 we investigated, 22 were found to have no panel switching issues. Overall, only 12% of the models we investigated turned out to be at risk, and these seemed mainly to be 32-inch TVs.

Across both manufacturers' models, we found a huge number of different panels, some of which were made by Samsung-Sony, while others were made by Sharp, CMO etc. Note that each of these panels has its own specific characteristics.

LCD Panels: Strengths and Weaknesses


Sony Bravia 40HX803
Vign 130
[tab_prix2(,,,8890,id_ln,,,)]
Sony Bravia 40EX713
Vign 130
[tab_prix2(,,,9774,id_ln,,,)]
Toshiba Regza 46WL768
Vign 130
[tab_prix2(,,,10275,id_ln,,,)]



- Sharp makes ASV LCD panels. In the past, these panels were inferior in quality but considerable progress has been made in the latest generation. Their responsiveness has improved (approx. 8 ms ghosting time) and the contrast is very good (over 3000:1), even if colour reproduction could still be better (delta E under 3). Their real weak point is their tight viewing angles.
We found Sharp panels in TVs made by Sharp, Samsung, Sony and Philips. Sony seems to be a particular fan, as this is its panel of choice (and rightly so) for 3D TVs (the Sony Bravia 40HX803, for example).

- Samsung-Sony makes PVA LCD panels, the most recent of which are excellent. They're a bit like a better version of ASV panels, as they have wider viewing angles, a very low ghosting time (8 to 10 ms), contrast of over 4000:1, but still have colours that could be better. The only problem is that there are several generations of PVA panel, the worst being almost twice as bad as the best, with a ghosting time of 15 ms, a contrast ratio under 2000:1 and tight viewing angles. The use of a PVA panel is therefore no guarantee of quality.
A recent panel: Sony Bravia 40EX713.
An older panel: Toshiba Regza 46WL768.


Samsung LE40C630
Vign 130
[tab_prix2(,,,9365,id_ln,,,)]
Samsung UE32C6000
Vign 130
[tab_prix2(,,,10203,id_ln,,,)]
Philips 42PFL6805H Econova
Vign 130
[tab_prix2(,,,9873,id_ln,,,)]



- AU Optronics (AUO) produces the best MVA LCD panels. AUO is something of a latecomer to this type of technology but it made fast progress and improved quality quickly. However, its MVA panels still can't match the best PVA panels out there. MVA panels made by AUO are about equivalent to old-generation PVA panels, with ghosting at around 15 ms, contrast near 2000:1 and viewing angles that could be better. Most 37-inch TVs (among others) seem to be equipped with MVA panels from AUO.
MVA panel by AUO: certain Samsung LE40C630 TVs.

- CMO produces a different type of MVA LCD panel that we've generally found not to be as good as those made by AUO. CMO panels just seem to be less well made. They have the same basic advantages and disadvantages as AUO MVA panels, but colour reproduction in CMO panels is often inferior. Plus, even the most accurate of manual adjustments can't always correct this.
MVA panel by CMO: Samsung UE32C6000.

Lg 47lex8 p364 10173 35- LG-Philips makes its own type of LCD panel, known as IPS panels. These work differently to ASV, PVA and MVA panels, even though they're based on a very similar technology to MVAs. One advantage IPS panels have over the competition is their wide viewing angles, which can almost match plasma screens. Otherwise, the quality of IPS panels depends on the backlighting used. The worst panels have a fairly low contrast and a black that we think looks washed out (Philips 42PFL6805H Econova, with contrast measured at just 1140:1). At the other end of the scale, the LG 47LEX8 we recently tested blew us away with its combination of an IPS panel and LG's 'Nano' (matrix) LED backlighting! This pairing is so good that OLED technology could have trouble gaining ground in the market. In the past, IPS panels were very bad for ghosting (over 20 ms and blurring in scenes of fast movement) but this has now been improved to a pretty good 11 ms, on average.

Our Hopes for 2011

2011In an ideal world, all the TVs sold under the same product name or reference number would be truly identical! Unfortunately, identical panels across the board seems to be too much to ask. We can therefore only hope that:
- the product specifications for each type of panel become stricter and more thoroughly checked by manufacturers;
- that manufacturers stop using different types of technology in one product! Mixing PVA panels with MVA panels is not acceptable. However, we can understand and tolerate the use of MVA panels from different manufacturers (so long as the colours are well calibrated). We can also understand swapping ASV panels for recent PVAs, but that's it! We don't want to see any mode dodgy combinations in 2011!

We would also like manufacturers to systematically change the name or reference number of a TV each time they use a different type of panel!

36 1708 2A Look Back Over our Investigations

As you can imagine, we didn't just come to these conclusions over night. Our investigations into panel switching started all the way back in 2007, with the then-popular Samsung SyncMaster 226BW monitor. It was this model that first brought panel switching to light, with the successive release of three different versions of the display.

We first got word of panel switching in TVs in August 2010, when it was exposed in the forum of our French sister site by a worried reader going by the name of cepseudoexistedeja.

Filters

ADVERTISING