Home Theater/dlp versus lcd

Advertisement


Question
I have been shopping around for a new television.  I was looking at projection t.v.'s when a salesperson told me I would want a lcd t.v.  I have just regular cable coming into my house and he said projections would not satisfy me and I want to be able to watch from sides.  So I decided on the hitachi 50v500a 50 inch rear projection lcd.  Reviews I have read have been great but now I hear about the dlp.  When spending this kind of money, I want to make sure I get want will suit my needs.  I have free cable so I cannot see switching to satelite or digital cable but I still want to get at least a 50 inch and still have superior picture.  I hope you can guide me in the right direction.  Thank you so much.

Answer
LCD TV typicall refers to a direct-view LCD panel, like a laptop PC screen.  Rear Projection systems shine a light onto a screen from behind to make the image.  LDC Rear projection can suffer from a problem called "screen door effect."  If you look closely at a LCD panel, you will see the screen is made up of hundreds of thounsands of little blocks called pixels.  In a LCD RPTV system, if there are not enough pixels (resolution) for the size of the projected image, you will see the lines between the pixels on the screen.  Just like if you looked at a laptop screen with a magnifying glass.  With the LCD RPTV, you are taking a small LCD panel and projecting it onto a much larger screen.  When you blow up everything like that, the pixels appear bigger, and so do the lines between them.  It can be compared to looking through a screen door.  However, with enough resolution on the LCD screen, you really don't have that problem.

DLP is a technology that uses a moving color wheen to project an image.  The best DLP projectors are called "3 chip" one for each primary video color- red, green, blue.  DLP does not have the screen door effect of LCD, but can have its own problems.  For one, fast moving objects on some cheaper DLP systems produce a rainbow effect as the obect moves across the screen, because the color wheel can't keep up.  One-chip DLP systems often don't have the color clarity  and sharpness of 3-chip systems.

Personally, for RPTV, I prefer large-gun CRT's.  A RPTV with 9-inch CRT's will produce the best image possible in a rear projection setup.  Besides being able to fully resolve 1920x1080 HDTV, it can do multiple scan rates, which makes lower-res stuff look better.  LCD and DLP are digital displays- meaning they have a set number of pixels.  All material- HDTV, DVD, cable- must be up or downconverted to this resolution.  The conversion can cause quality to be lost.  Electronically, converting video is not easy.  Good video scalers cost thousands, so you won't typically find a quality one in a TV.  

The advantage of analog CRT's is they can do multiple scan rates, so every source you feed into the system gets displayed in its native form, which generally insures a better picture

Good luck

Bob

Home Theater

All Answers


Answers by Expert:


Ask Experts

Volunteer


Bob Z.

Expertise

I can answer questions about digital television, including display devices, over-the-air reception, formats, and recording. I am a certified broadcast engineer, and H/DTV watcher since the early days. I also can answer general home theater questions as well.

Experience

Broadcast Engineer, (CBT)
DTV early adopter


Organizations belong to
Society of Broadcast Engineers

Publications
TV Technology
Broadcast Engineering

©2014 About.com. All rights reserved.