Mitsubishi Electric

There are several types of TV display technologies currently in the marketplace that are considered 3DTV and 3D Ready. These current TV display technologies include DLP, Laser, Plasma (PDP) and LCD. The first commercially available types of 3DTVs use active shutter glasses for viewing 3D. 3DTV displays that use eyewear free or auto-stereoscopic approaches are available but are several years away from being commercially viable.

The DLP technology being used in 3D Digital Cinema is also commercially available in the forms of rear projection and front projection consumer products. DLP technology for the home creates images using a Digital Micro-Mirror Device (DMD) that switches light output at speeds of 4-6 microseconds. This speed enables DLP to have very good rendering of 3D contents as well as HDTV. In order to display 3D on DLP 3DTVs, the technology uses a display format called checkerboard as shown in Figure 1. This display format has been used for several years and produces very high quality 3D effects on the TV.

The checkerboard format is used to pack the left/right images into one frame. As it is a static format, there is no need to "page-flip" or sync the refresh at all. The left and right images are sampled using the native offset diagonal sampling format of the DMD. The two views are then overlaid and appear as a left and right checkerboard pattern in a conventional orthogonal sampled image. This format preserves the horizontal and vertical resolution of the left and right views providing the viewer with the highest quality image possible with the available bandwidth. Watch Checkerboard Video

Figure 1

Some of the key benefits for DLP include large screen affordability, value and high quality rendering of 3D and HDTV contents.

DLP technology in the home uses active shutter glasses. These active shutter glasses use a sync signal from the display itself using a white light synchronization protocol developed by Texas Instruments. The active shutter glasses must be labeled DLP Link in order to function with this protocol. Other types of active shutter glasses can use a separate emitter that usually comes packaged with the glasses.

LCD display technology has been around for several decades. While first used in small screens and computer screens, this display technology is now available in much larger screen sizes for the TV display market. LCD TVs create images by using a combination of a backlight (usually CCFL and more recently LED) along with an LCD panel.

LCD TV utilizes polarized light in two thin polarized panels sandwiching a liquid crystal gel which is split into pixels. A two dimensional grid of wires is used to activate each pixel individually. These pixels can be darkened depending on the voltage applied. A darkened pixel polarizes at 90 degrees to the panels, thus blocking light from passing through.

Early LCD TV had problems with ghosting when any fast movements occurred and could only be viewed when looking directly at the TV. These issues have been ironed out as has the problem of providing a large screen version of the technology. In order to address many of the ghosting issues for fast movements, LCD TV manufacturers have adopted higher frame rates. These frame rates are 120Hz, 240Hz and possibly higher. Not only are these higher frames needed to improve motion in fast motion video, but it is also required for 3D. In addition to frame rate the response time of the panel is typically in 4 to 8ms.

In order to display 3D on LCD TVs, the technology uses a display format called page flipping as shown in Figure 2. The page flipping format (also called frame sequential) is basically displaying the left and right frames of the video in a time sequential manner. For LCD TVs, this format requires very high frame rates in order to ensure there is no visual delay to the consumers' perception of 3D. Watch Flipbook video

Figure 2

LCD technology in the home uses active shutter glasses. These active shutter glasses use a sync signal from the display or a separate emitter that usually comes packaged with the glasses.

The basic idea of a plasma display is to illuminate tiny, colored fluorescent lights to form an image. Each pixel is made up of three fluorescent lights -- a red light, a green light and a blue light. Just like a CRT television, the plasma display varies the intensities of the different lights to produce a full range of color.

Unlike LCD TVs, Plasma 3D TVs do not suffer from motion blur and ghosting issues. Plasma TVs have almost instantaneous pixel refresh rates and this results in a lack of ghosting and blurring in fast motion videos. In older Plasma TVs there used to be a motion trail effect due to the phosphor lag time of the plasma screen (the lag time is the time it takes the phosphor of the screen to stop glowing after it stops being activated). However, current 3D Plasma TV manufacturers have solved this problem by developing newer phosphors with extremely low lag times.

In order to display 3D on PDP TVs, the technology uses a display format called page flipping as shown in Figure 2. The page flipping format (also called frame sequential) is basically displaying the left and right frames of the video in a time sequential manner. For LCD TVs, this format requires very high frame rates in order to ensure there is no visual delay to the consumers' perception of 3D. Watch How Stereopsis Works

PDP technology in the home uses active shutter glasses. These active shutter glasses use a sync signal from the display or a separate emitter that usually comes packaged with the glasses.