If you purchased a Mitsubishi or Samsung DLP rear projection HDTV over the last 3 years, you might want to check your owners manual, spec sheet or back of the TV to confirm you are 3D ready. The fact is that many owners are unaware of the feature since it isn’t the reason they bought it to begin with. From experience in the field, many are bound to unwittingly consider replacing it for a 3D ready display when they may not need to.

If you are one of the current 2 million 3D DLP owners, you are well over $1000 ahead of the 3D game, but may have to buy a 3D adapter from Mitsubishi, the 3DC-1000, which will accept the new Blu-ray 3D standard of 48 Hz and apply the checkerboard 3D processing (I’ll go over that shortly). Mitsubishi has not provided a price at this time. There was no statement about accepting any potential broadcast 3D format which is understandable since that standard doesn’t exist yet. Mitsubishi did throw out that compatible 3D Blu-ray players might show up. Throwing in the mod to support 2 million 3D ready HDTVs might be tempting for a manufacturer but nobody has said as much at this time. Notice I said 2 million. I see no reason why the Samsung DLPs won’t be fully compatible since they use the same 3D standard as Mitsubishi.

There Is Another “But”…

This "but" refers to the checkerboard processing. DLP rear projection displays were, and for Mitsubishi continue to be, wobulated DLP displays (the mirror wobulation is a Hewlett Packard invention). DLP is a marketing name for what is technically called the DMD chip, that thing with millions of tiny mirrors you may have heard about. Texas Instruments, the DMD chip manufacturer, uses the marketing term SmoothPicture since the process makes it difficult to detect individual pixels (which also reduces the ability to fully resolve pixel detail). That means the DMD chip is half resolution, 960x1080, and a wobulation mirror runs at 120 Hz creating a full 1920x1080 response at 60 Hz. This reduces the cost of DLP product and appears to have been solely used for rear projection applications (there has never been a full 1920x1080 DMD chip in an RP DLP display). The ability to hide pixel structure also limits the clarity of a high resolution 1920 line response. The response exists, it can be seen, it has some contrast, but it is significantly different lacking the perfectly sharp individual pixel response and contrast level of a full resolution DMD chip.

If this is news to you don’t let it bring you down. I still have one; many calibrators had or still have one along with many a videophile. Resolution isn’t everything and just one of many facets to performance viewing. You have to do a lot of research and typically spend more money, at times way more money, to remove all warts. Topping it off, if you are like most folks, then you are sitting too far away to even see a 1920 response, making it real hard to suggest you are losing anything!

The cool thing is this technology easily dovetails into a 3D stereoscopic application except for one seemingly un-cool fact; the wobulation mirror does not run at 240 Hz which is required to provide full 1920x1080 resolution to each eye. On the surface that means these rear projection DLP products are 1920x1080 in 2D and 960x1080 in 3D. Just like 2D, the left and right eye images of 3D are split up in a half resolution checkerboard pattern that when combined by your brain (just like the old interlaced NTSC video) appears as a single 3D high resolution image. The huge difference is in 3D mode it throws away half the information for each eye. It would be easy to assume that you are getting half the performance but there is a solid argument against that.

The left and right eye images are actually part and parcel of the same image simply separated by the 3D encoding of angular information. What is being thrown away for one eye exists in the other and vice versa. When put together you arguably get one seamless image and no loss!

Clearly, tricking the brain is not the same thing as actually delivering 1920x1080 to each eye yet all DTV broadcast versions will be forced to use a similar system. During the 3D demo at the Mitsubishi booth it all appeared to look HD but I'll be the first to tell you that doesn't mean much because it's all a new experience for me and it will be a while before I know in the future what I didn't know then! I won't be convinced that I wasn't missing anything until there are 3D 1920x1080 resolution patterns to prove it. All that said it is more than reasonable to conclude that what I viewed didn’t suffer anymore loss in performance than what you get in 2D mode from this technology. The performance hit for broadcast 3D may be quite similar in which case most will think it isn’t any different at all!

There are three main points I want to leave you with.

• Rear projection DLP wobulates a 960x1080 DMD chip and can't provide 3D 1920x1080 to each eye
• A 1920x1080 DMD chip can provide 3D 1920x1080 to each eye
• This is a great example of how 3D display technology can differ and how performance viewers need to do their homework or hire a pro

More Useful Links

Introducing DLP 3-D TV PDF

Posted by Richard Fisher, April 6, 2010 8:32 AM