Several major difficulties of naked eye 3D technology

July 19 On July 14, 2011, Toshiba Corporation of Japan officially released the F750 laptop computer with glasses-free 3D function. The birth of this product not only caused a huge wave in the laptop industry, but also marked a milestone for the entire consumer electronics industry. Because with the release of this glasses-free 3D laptop computer, electronic products with glasses-free 3D function have penetrated into almost all consumer electronics fields, and are no longer limited to the previous limited fields such as game consoles, DC/DV, etc.

Toshiba's 12-inch and 20-inch glasses-free 3D TV advertising effects pictures released in Japan

In fact, at the beginning of this year, there have been officially commercialized naked-eye 3D TVs in the Japanese home appliance market. They are two small-sized naked-eye 3D TVs (12 inches and 20 inches) launched by Toshiba. However, the sizes of these two products are too small to be considered as real mainstream products. After their launch, they did not create any special sensation among the color TV industry and consumers.

So for flat-panel TVs larger than 32 inches, which are more practical for ordinary consumers, what are the problems that hinder the popularization of naked-eye 3D technology? What is the current development status of naked-eye 3D technology? When buying a TV now, should you consider upgrading to "naked-eye 3D" in the future? This article will give you the answers.

There is also "internal competition" in naked-eye 3D technology

"Glass-free 3D" is just a functional descriptive term. If we further subdivide it, glasses-free 3D technology can also be divided into several completely different types. Different glasses-free 3D technologies have different principles and the final imaging effects are also different. It can be said that glasses-free 3D technology itself is still in the process of development and change, and has not yet reached a particularly perfect level.

There are two common and relatively mature naked-eye 3D technologies: one is the parallax barrier type and the other is the lenticular lens type. Devices with smaller display areas tend to use the former, while larger devices such as TVs and monitors tend to use the latter.

The two mainstream naked-eye 3D technologies have their own advantages

The parallax barrier type naked eye 3D technology uses a specific algorithm to arrange images alternately, and then separates the images visible to the left and right eyes through the parallax barrier set between the display backlight and the liquid crystal panel. Since the left eye or right eye views the screen at different angles, the image can be allocated to the left eye or right eye by blocking the light with this angle difference, and the user's brain synthesizes these two different images into a three-dimensional image with spatial depth information.

There are two common and relatively mature naked-eye 3D technologies: one is the parallax barrier type and the other is the lenticular lens type. Devices with smaller display areas tend to use the former, while larger devices such as TVs and monitors tend to use the latter.

The two mainstream naked-eye 3D technologies have their own advantages

The parallax barrier type naked eye 3D technology uses a specific algorithm to arrange images alternately, and then separates the images visible to the left and right eyes through the parallax barrier set between the display backlight and the liquid crystal panel. Since the left eye or right eye views the screen at different angles, the image can be allocated to the left eye or right eye by blocking the light with this angle difference, and the user's brain synthesizes these two different images into a three-dimensional image with spatial depth information.

This technology has been around for a relatively long time and is relatively easy to implement. However, its disadvantages are also obvious, that is, the backlight module is blocked by the parallax barrier, which reduces the brightness. At the same time, the resolution of the screen will also decrease in 3D mode. For example, Sharp has launched a naked-eye 3D display using this technology. In 3D mode, not only is the brightness only half of that in 2D mode, but the resolution will also drop to about 120dpi, which is only half of that in 2D mode.

The lenticular lens 3D technology adds a dense layer of lenticular lenses to the top layer of the LCD panel, so that the pixels of the image under each lenticular lens are divided into several sub-pixels, and the sample lens can project each sub-pixel in different directions. Therefore, when the eyes watch the display from different angles, they see different sub-images.

The advantage of the lenticular lens naked-eye 3D technology is that there is no module to block the backlight, so the display brightness is not affected. However, it has strict requirements on the angle at which the audience views the screen. If the angle is not appropriate, the three-dimensional effect may not be seen.

In addition to these two naked-eye 3D technologies, there are also technologies in the industry that achieve naked-eye 3D by changing the direction of the light source (Sony), and "MLD" technology that achieves stereoscopic effect by stacking multiple layers of LCD screens, etc. However, these technologies are either in the laboratory stage or difficult to implement on TV sets due to cost issues. It seems that it is still difficult to become the mainstream naked-eye 3D technology in the future.

Nintendo's 3DS portable game console uses parallax barrier 3D technology

Among the naked-eye 3D devices currently on the market, parallax barrier 3D technology is a more common type, which is mostly used in small-sized devices such as 3D mobile phones (Sharp SH8168U) and portable game consoles (Nintendo 3DS). The 56-inch 3D TV displayed by Toshiba in China this time uses cylindrical lens technology, because the TV has higher requirements for brightness and resolution, and the former is not competent for more demanding application environments.

Several major difficulties that plague naked-eye 3D technology

Brightness, resolution, viewpoint, and several major difficulties that plague naked-eye 3D technology

In fact, no matter which naked-eye 3D technology is used, it still faces considerable challenges to achieve large-scale commercialization. Even the relatively mature parallax barrier naked-eye 3D technology and lenticular lens 3D technology described above have their advantages and disadvantages relative to each other. If compared with the existing shutter 3D technology or polarized 3D technology, there is still a big gap.

Regardless of the type of naked-eye 3D technology, the most common problem currently faced, and the biggest problem, comes from the resolution in 3D mode.

For example, the naked-eye 3D game console 3DS released by Nintendo not long ago has a main screen resolution of 800×240, but when switched to 3D mode, the resolution becomes 400×240, that is, the left and right eyes each correspond to half of the horizontal pixels. Therefore, the 3D picture that players finally see is actually only a resolution of 400×240; and the naked-eye 3D mobile phones released by Sharp and LG before also face the same problem. As long as they switch to 3D mode, the resolution will inevitably be lost to a large extent.

Toshiba's newly exhibited naked-eye 3D TV is still under development and has three optimal viewpoints. But for real applications, three viewpoints are obviously not enough.

The second problem is the viewpoint of naked-eye 3D. In fact, whether it is Nintendo's 3DS game console, or those naked-eye 3D mobile phones, 3D cameras, and video cameras, if you want to see a more vivid 3D effect, you need to meet the appropriate angle and distance, otherwise the 3D effect will be reduced at best, and in serious cases, you can only see images full of double images.

In addition to the imperfections of naked-eye 3D technology itself, another factor affecting the popularization of naked-eye 3D TVs can be summarized as the obstacles from existing 3D technology. After all, in terms of cost, timeliness, etc., existing 3D technology is more pragmatic than naked-eye 3D technology.

Existing 3D technology also poses a substantial challenge to naked-eye 3D

The most commonly used 3D imaging technologies for 3D TVs are shutter 3D and polarized 3D. The biggest feature of these two 3D technologies, or their common "disadvantage", is that viewers need to wear 3D glasses, otherwise they will not be able to see the 3D stereoscopic effect. But apart from that, these two 3D technologies still have many advantages.

Existing polarized 3D technology has made glasses highly lightweight, and can even be installed in front of ordinary myopia glasses in the form of clips, without significantly reducing the comfort of the audience.

For example, in the most important aspects of image quality and viewing experience: resolution, brightness, and viewing angle, existing 3D technologies have advantages that naked-eye 3D technology cannot catch up with in a short period of time. For example, shutter-type 3D TVs can achieve full HD stereoscopic images, while polarized 3D TVs have the advantages of high visual comfort and wide viewing angles, which directly address the shortcomings of naked-eye 3D technology.

Shutter 3D technology can display full HD stereo images. If the physical resolution of the panel is improved, its 3D resolution will also be improved.

More importantly, the cost of existing 3D technology is really cheap. For example, active shutter 3D TV basically adds some driving circuits on the basis of 100Hz LCD TV to achieve the upgrade of 3D function. The cost is not much higher than that of ordinary 2D 100Hz TV. Polarized 3D TV only adds a layer of polarizing film on the LCD panel, and polarized glasses are very cheap. The overall cost is even more advantageous than shutter 3D TV. Therefore, with the increase in production scale and further reduction in prices, 3D function will inevitably become a standard function of all flat-panel TVs in the future, and 3D TV will become a very common home appliance without consumers having to pay too much extra for it.

We can imagine that when naked-eye 3D TV meets a very mature and economical 3D TV, even if it has the advantage of not needing to wear glasses, will this advantage still have a great chance of winning? After all, many consumers only want to have stereoscopic vision when watching movies occasionally. In most other cases, they are still accustomed to the conventional 2D mode.

Taking all the above factors into consideration, it is not difficult to draw such a conclusion: although naked-eye 3D technology is convenient and allows viewers to see stereoscopic images without wearing 3D glasses, it is not yet truly practical in applications such as televisions that require high image quality. Therefore, we cannot be overly optimistic about the commercialization of naked-eye 3D TVs. Before the emergence of revolutionary naked-eye 3D technology, glasses-type 3D TVs, which are less comfortable to use but have better image quality and price, are still the first choice for ordinary consumers.