Hello, I’m Yoo-chul Kim and I am in charge of software and global R&D strategy in the CTO Technology Strategy Team. What did you think of my last post, ‘Delving into the 3D TV Technology Dispute through Picture Quality’. Following that post, Today, we are going to talk about the glasses, which is an important factor in choosing 3D TVs.
[Notes on Terms]
First, let’s take a look at the terms.
Polarized Glasses = Polarization 3D = Passive method,
Shutter Type Glasses = Alternate-frame sequencing = Active method.
The panel is what produces 3D images in FPR 3D TVs, and that is why polarized glasses (a.k.a. Passive glasses) are used. On the other hand, for SG (Shutter Glasses) types, the glasses play a critical role in realizing 3D images. That is why shutter glasses type, a.k.a. active glasses are used.
Active type glasses are usually referred to as SG type. The FPR (Film Patterned Retarder, film type polarized glasses) can be seen as a further technological advancement over Passive type technology.
So for the sake of convenience, let’s refer to these technologies as SG type and FPR type. At times, I may need to compare the old kind of Passive type with FPR type, and in this case I will be referring to them as PGR (Polarized Glasses Retarder) and FPR (Film Patterned Retarder) types.
Heavy, Pricey, or Stylish
SG types utilize shutters by inserting liquid crystal between two polarized plates and sending electric signals. This requires batteries, charging and circuits, and that really drives up the cost of the glasses. Of course, it is also more difficult to keep the weight of the units down.
FPR type glasses only require one polarized plate, so it is very similar to sunglasses. Normally, sunglasses are made by coated UV protective film, and prices greatly differ depending on the material or design. FPR type is very similar. You can expect to see partnerships with famous global luxury brands to develop FPR type 3D glasses that can also be used as sunglasses.
How many different 3D products can you enjoy with one pair of glasses?
One of the major issues during the recent 3D TV dispute is whether or not this pair of glasses is compatible with other products. To use 3D glasses for TVs and other various 3D products, there has to be a standard viewing angle and brightness between TV and FPR type glasses. LG’s FPR 3D products, ranging from TVs, projectors, monitors and notebook computers, can be viewed with a single pair of glasses. FPR film (manufactured by LG Display) used in FPR types, is also supplied to Real D, and Master Image, the 1st and 2nd ranked companies, respectively, that supply 3D systems for movies theaters in the world. This means that you can use the same pair of glasses to watch 3D movies in the theater (Types may vary depending on the theater). You can use the same pair of glasses for almost all existing TVs, projectors and more.
Glasses for SG types also need an interface standard between the TV and glasses. Currently, different manufacturers have different orders between the left and right lenses, different timing, and different interval times in between flickers. And, noise may occur due to fluorescent lights used in the room or infrared signals. This is precisely why CEA is moving to set a standard, and in a few years time, you will be able to share the same pair of glasses among products.
Enjoy 3D content from all LG 3D products with a single pair of CINEMA 3D glasses
To Sit or To Lay
There has also been a lot of discussion about whether you can watch 3D TVs while lying down, and this has to be viewed from 2 different perspectives.
1) Does the screen darken for SG types when you turn your head?
As mentioned above with the weight and price, both SG and FPR types require polarized lenses. Our domestic competitor uses linear polarized lenses in the SG type glasses, and when you start to turn your head, the screen darkens until finally you can’t see anything at all. FPR types use circular polarized lenses, which don’t make the screen darker even when you turn your head.
A competitor in Japan coated a film that converts linear to circular on top of the circular polarized lens in their SG type glasses. This was unveiled at an exhibition and the product also prevented the screen from becoming darker. In the end, the issue was the extra cost regarding the extra piece of film, and it was not about the difference between SG or FPR types.
2) If you are viewing through circular polarized lenses, can you watch 3D TVs while lying down?
3D images are created for the left and right eye. The left eye sees the left image and the right side sees the right image. So, if you are lying down on your side, the left eye should see the top image, and the right eye should see the bottom image, but this isn’t the case. Even if you are lying down, the left eye continues to see the left image, and the right eye will continue to see the right image.
Even so, we receive these images as 3D. The human brain is not that limited. Of course, 3D effects will not be as great as watching it in an upright position. However, I think that we may see new technology that may overcome this shortcoming in the near future. Even now, LG is working quickly to develop 3D that can be viewed without glasses, so I’m sure we’ll see a solution to the viewing angle.
Less Crosstalk Means Less Dizziness
Crosstalk refers to the ratio of when the left and right images are not sent to the desired position and overlap. So less crosstalk (lower percentage) means less possibility of becoming dizzy, and this in turn could be seen as an outstanding 3D display.
Theoretically FPR types have no chance of generating crosstalk. This is because each pixel is set to be sent to a certain eye. However, depending on the evenness of the film and the circuits, subtle crosstalk may be discovered. The numbers are measured to be 0.6%, and are suggested to be 0.0001%.
There are many efforts to reduce crosstalk in SG types. Just up until last year, some products showed crosstalk ratios of over 10%, but recent products have been measured to be 2.6%, suggested to be 1%. However, we will still have to wait and see how much more it can be reduced in SG types.
Flicker gives you headaches and makes you tired when watching 3D TVs
Flicker, refers to well… flickering. The biggest side effects of 3D TV viewing are tiresome eyes and headaches. You can think of fluorescent lights 10 to 20 years ago to get a better idea. 50Hz fluorescent lights flicker approximately 100 times per second. This kind of flicker is very tiresome to the eyes. That is why inverter stands were developed. Inverter stands use a part called ballast stabilizers to increase the flickering to over 10 thousand times per second. This dramatically decreased the tiring of the eyes. Most fluorescent lights these days have ballast stabilizers.
CRT TVs flickered 50 times per second. LCD TVs in the market today flicker 100, 200, and 400 times per second, makes it easier on the eyes. PDP TVs flicker up to 500 times per second, so it is the easiest on the eyes.
FPR types are no different from watching 2D content of LCD or PDP TVs. Most LCD TVs are 200 Hz, and this causes minimal flickering. (Although measurement standards are not clear, measurements by TUV show flickering measuring approximately 0.001. The measurements must be less than 1 to be certified as flicker-free).
200Hz SG type TVs generte about 50 images for each eye ever second. To reduce crosstalk, black images are shown to the eyes even after the shutters open, that is why you see not 100, half of 200, but about 50 images. In this case the flickering can become worse. (Measurements by TÜV show approximately 3)
Writer (guest) – Yoo-chul Kim
Yoo-chul Kim is in charge of software and global R&D strategies in the CTO Technology Strategy Team. He is also active as an expert in technology promotion through exhibitions, lectures and recruiting. Kim will be talking about how new technology impacts our lives. On a personal level, he is interested in games, good places to eat and comic books. He longs for the day when people can share more information more conveniently.