Classification, advantages and disadvantages of naked-eye 3D stereoscopic display technology

At present, 3D display technology can be mainly divided into eye-type and naked-eye type. Eye-type 3D display technology was developed earlier, and the solution is relatively mature. It has been used in the commercial field for many years. All 3D flat-panel TVs launched this year are eye-type products. However, eye-type 3D TVs require customized 3D glasses, which may be inconvenient for consumers who already wear glasses. Naked-eye 3D does not require additional equipment to allow viewers to appreciate the 3D effect. It is generally welcomed by consumers and valued by manufacturers. Naked-eye 3D technology is the current development direction of 3D display technology.

Naked 3D display technology

From a technical point of view, naked-eye 3D can be divided into three types: barrier, lenticular lens and directional backlight. The biggest advantage of naked-eye 3D technology is that it is free from the constraints of glasses, but there are still many shortcomings in terms of resolution, viewing angle and viewing distance.

When watching, the audience needs to keep a certain distance from the display device to see the 3D effect image (the 3D effect is greatly affected by the viewing angle). There is still a certain gap between the 3D image and the common polarized 3D technology and shutter 3D technology. However, the LCD panel industry giant AUO and the R&D giant 3M are already actively conducting research and development, and it is expected that some naked-eye 3D display devices will be mass-produced in the next two years.

Light barrier

Light barrier 3D technology is also known as parallax barrier or parallax barrier technology. Its principle is similar to polarization 3D and was successfully developed by engineers from Sharp's European laboratory after more than ten years of research. Light barrier 3D products are compatible with existing LCD liquid crystal processes, so they have advantages in mass production and cost, but the image resolution and brightness of products using this technology will decrease. The implementation method of light barrier 3D technology is to use a switch LCD screen, polarization film and polymer liquid crystal layer, and use the liquid crystal layer and polarization film to create a series of vertical stripes with a direction of 90°.

These stripes are tens of microns wide, and the light passing through them forms a vertical thin stripe pattern, which is called a "parallax barrier". This technology uses the parallax barrier placed between the backlight module and the LCD panel . In the stereoscopic display mode, when the image that should be seen by the left eye is displayed on the LCD screen, the opaque stripes will block the right eye; similarly, when the image that should be seen by the right eye is displayed on the LCD screen, the opaque stripes will block the left eye. By separating the visible images of the left and right eyes, the viewer can see the 3D image.

Advantages: Compatible with existing LCD processes, so it has advantages in mass production and cost.

Disadvantages: Low screen brightness, resolution decreases inversely as the number of images broadcast by the display increases at the same time

Cylindrical lens

Lenticular lens technology is also known as double convex lens or micro-column lens 3D technology. Its biggest advantage is that its brightness will not be affected. The principle of lenticular lens 3D technology is to add a layer of lenticular lens in front of the LCD screen so that the image plane of the LCD screen is located on the focal plane of the lens. In this way, the pixels of the image under each lenticular lens are divided into several sub-pixels, so that the lens can project each sub-pixel in different directions. So when both eyes watch the display from different angles, they see different sub-pixels. However, the gap between pixels will also be magnified, so sub-pixels cannot be simply superimposed. Let the lenticular lens and the pixel column not be parallel, but at a certain angle. In this way, each group of sub-pixels can repeatedly project the viewing area instead of only projecting a group of parallax images.

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The reason why its brightness is not affected is that the cylindrical lens does not block the backlight, so the brightness of the picture can be well guaranteed. However, since the basic principle of its 3D display is still similar to the parallax barrier technology, the resolution is still a difficult problem to solve.

Advantages: 3D technology has better display effect and brightness is not affected

Disadvantages: The related manufacturing is not compatible with the existing LCD liquid crystal process and requires investment in new equipment and production lines.

Point to light source

3M's directional light source 3D technology

3M is the company that has invested a lot of energy in directional backlight 3D technology. Directional backlight 3D technology uses two sets of LEDs , a fast-response LCD panel and a driving method to allow 3D content to enter the viewer's left and right eyes in a sequential manner, exchanging images to produce parallax, and then the human eye can feel the 3D effect. Not long ago, 3M just demonstrated its successfully developed 3D optical film. The product's interview realized that real 3D stereoscopic images can be displayed on mobile phones, game consoles and other handheld devices without wearing 3D glasses, greatly enhancing communication and interaction based on mobile devices.

Advantages: Resolution and transmittance are guaranteed, will not affect the existing design architecture, and 3D display effect is excellent

Disadvantages: The technology is still under development and the product is not mature.