High-Def Alphabet Soup: PDP LCD DLP LCoS! What is the Best Type of HDTV for Me?

So, you want to buy an HDTV? I sometimes think it is easier to buy a car than a new television. All cars use the same type of internal combustion engine and adhere to measurement standards that allow for comparison (i.e. horsepower and gas mileage ratings). In the HDTV arena, things seem to be mushier. Some manufacturers will decide to publish viewing angles and brightness measures…and others will not. Attributes like picture quality and color vividness are just plain difficult to measure and communicate. Additionally, a manufacturer may list a contrast ratio, but fail to mention whether it is a dynamic or static. I can’t decide if comparing televisions is more like herding cats or nailing Jell-o to a tree. But that is not going to stop me from trying to establish some basic guidelines to compare types of HDTVs. Just keep in mind that there is no replacement for your own first-hand evaluation of any television's picture.

The one part that I will spare you is all of the behind-the-scenes, didn’t-need-to-know, I-couldn’t-care-less detail of how each technology works. I’ll skip over the details of how electricity between plates of glass will excite gases to a state of flatulence, emitting a spectrum that is tantalizing to the senses. Most folks don’t need to know that millions of mirrors the size of flea dandruff turn on hinges that are thinner than a pubic hair and reflect light in a bazillion colors ranging from back-of-the-throat mucus green to falling-off-a-cliff-to-my-death pale yellow. I will spare you the detail. You will thank me.

Another thing to understand is that evaluating TV types is like playing pin-the-tail-on-the-donkey with the donkey on a racing car. The moving target requires constant re-evaluation. Each of the five HDTV types discussed here have distinct advantages and disadvantages, but manufacturers work to address these issues and improve upon prior models. The plasmas have addressed their prior burn-in issues. Newer LCDs will start having new features to improve motion clarity. DLPs have worked to eliminate its rainbow effect. Yesterday’s rules of thumb can quickly turn into today’s myths.

Flat Panel: PDP & LCD
Let us start our discussion with the cream of the crop, the flat panel televisions. If you want a wall-mountable television (or just something really thin), then Plasma or LCD (liquid crystal display) will do the trick at about 4 inches of thickness. Both continue to improve upon their deficiencies, making the differences noted here smaller than ever. Plasma Display Panels (PDP) generally have deeper blacks and better color, but LCD TVs are brighter, making them better choices for well lit rooms. LCD televisions display static images better and continue to be the choice for PC connectivity. Quick motion display, on the other hand, is typically better on the plasma. At the last Consumer Electronics Show, however, many manufacturers showed interpolation methods to improve motion clarity on LCDs. In the near future, look for features like Clear Motion (JVC), Natural Motion (Philips), and – the award for the longest name – Motion Compensation Frame Interpolation (Samsung and Sharp). While LCDs are more prevalent for TVs 37" and under, Plasmas are still more popular in the over-60" range. The sweet spot of the market, displays of the 42" to 50" size, is where the greatest competition exists between the two technologies.

Rear Projection: DLP, LCD Projection, LCoS
If keeping your wallet fat is more important than making your television ultra-thin, then rear projection televisions may be the best option for you. These may be deeper than flat panels, but at 11" to 18" in depth, they are much shallower than your father's rear projection. Three main technologies dominate: DLP, LCD projection, and LCoS. While each has advantages and disadvantages, the DLP (digital light processing) appears to have the slight edge with deeper blacks, a good display of motion, and great capability of displaying still images from a PC. This technology from Texas Instruments, is the one touting millions of tiny little mirrors. Additionally, DLPs continue to dominate the very large 60”+ market. In the past, DLPs have been plagued by "rainbows", infrequent color streaks seen by some viewers. Newer DLP models with high speed color wheels have addressed this problem. LCD projection televisions have grown in popularity and are very price competitive near the sweet spot. The LCD's "screen door effect", a phenomenon where you can see the space between the image pixels, is only seen up close and will diminish with 1080p output. The LCoS (liquid crystal on silicon) technology has been sporadically used among manufacturers, and now has been rebranded as SXRD (Sony) and HD-ILA (JVC). With only these two major manufacturers left, LCoS has been kept out of the limelight. It is hard to go wrong with a good quality set using any of these technologies. They have all come a long way and provide outstanding pictures.

Viewing Angle
Besides console depth, one of the biggest differences between flat panels and rear projection TVs is the viewing angle. This term describes how far off-center you can view the television before you start to see deterioration of the image color and brightness. Plasmas and LCDs have horizontal viewing angles around 178° (note: be suspicious of any figures greater than 180° - this means that you see a good image when you sit behind the screen). The rear projection models suffer in this area, with horizontal viewing angles in the range of 130° to 160°. This, I argue, may be good enough for just about anyone. Any viewing position beyond this range just sucks anyway. If you are sitting at the outskirts of a 120° view, your image is significantly distorted, appearing to be half the width of an image viewed from the front (see graphical illustration). Any horizontal viewing position beyond the capability of TVs described here is just a poor place to watch HDTV.

The viewing angle of greater concern is the vertical viewing angle. For plasmas and LCDs, this continues to hover around 176°. This means you can practically have the TV hanging from the ceiling directly above you and you will see a colorful, bright picture (albeit scrunchy from the angle at which you are viewing). The rear projections, however, start to have significant deterioration 20°-30° above horizontal (i.e. a 40°-60° total viewing angle). At a viewing distance of 8 feet, that can be as little as 3 feet above eye level. Ideally, for ergonomic reasons, you want the TV to be as close to eye level, anyway. In making your decision, however, you need to keep in mind that rear project televisions have limitations on how high the TV can sit.

The Chart
Below is a chart that summarizes the main features of HDTVs and their relative ranking among the television types. Black level and brightness help make up the contrast ratios. Be careful when reading manufacturer specs on contrast ratios. A dynamic contrast ratio looks at the brightest vs. darkest points over time, where the static contrast ratio evaluates this for a snapshot in time. Very high dynamic contrast ratios are easier to achieve than static ones. An outstanding static contrast ratio may be 1,500:1, while it is not unusual to see a dynamic contrast ratio over 10,000:1. The criteria "XL Sizes" refers to the ability of the technology to delivery very large (60"+) televisions. Lastly, the "Price/Size" attribute describes how large of a screen you can buy with your dollar, regardless of other features. An overall rating is provided with all criteria given equal weighting.
Conclusion
While the bottom line of the chart shows the plasma technology on top, this is obviously using my choice of criteria and scaling of attribute differences. [Added 07/11/07: My opinion is not isolated, however, as CNETs Best HDTVs Overall had Plasmas in 6 of the top 10 spots.] It is often more useful, however, to consider your particular application and determine which criteria are important for your environment. For example, something as simple as wall mounting would eliminate the DLP technology from consideration. So with your own criteria and the knowledge gathered here, maybe you can make a little more sense of the high-def alphabet soup and create an informed buying decision.