India Broadband Forum

just4kix

Television sets' technology made progress by leaps and bound in the last decade. Ten years or so ago, we just had traditional Cathode Ray Tube (CRT) TVs. A typical CRT TV has a CRT and resident electronics such as tuner, audio amplifier and video converter. The first round of innovation started with the emergence of vitually flat or full flat TVs. Mostly such features were offered in high-end and large TV sets only. Today flat CRT TVs are a norm with even 14" flat TV.

Traditional CRT TVs and their issues
CRT or cathode ray tube is the old standard for televisions. The principle behind it is a vacuum tube that consists of an electron gun that is directed towards a screen coated in phosphor. The electron gun fires electrons at the screen causing the phosphor to heat up. This action causes colors on the screen which are used to produce an image that you watch. A 21" or 51 cm (diagonal) TV was considered good enough for the home. With the introduction of home theatre concept demand for large screen TVs zoomed. People wanted the largest TV set that they could afford.

But this presented with two problems. The first problem was the size of such a TV. The 21" TV was about 20" or so in depth. A large picture tube meant bigger depth. Most conventional homes could hardly find space to accomodate large TVs. CRTs became compact and this removed the problem to some extent.

The second problem was resolution. TV transmission was/is still standard defination which translates to:

• NTSC: 525 lines, 640 × 480 (VGA), 30 frames per second, interlaced scan.
• PAL: 625 lines, 640 × 480 (VGA), 25 frames per second, interlaced scan.

Standard definition is also known as 480i (480 vertical dots and 'i' for interlaced).

This meant that large the TV, the lesser the resolution (picture clarity). Interlaced scan refers to one of two common methods for "painting" a video image on an electronic display screen (the second is progressive scan) by scanning or displaying each line or row of pixels. This technique uses two fields to create a frame. One field contains all the odd lines in the image, the other contains all the even lines of the image. A PAL based television display, for example, scans 50 fields every second (25 odd and 25 even). The two sets of 25 fields work together to create a full frame every 1/25th of a second, resulting in a display of 25 frames per second.

In case of NTSC, it scans 60 fields every second (30 odd and 30 even). The two sets of 30 fields work together to create a full frame every 1/30th of a second, resulting in a display of 25 frames per second.

In short what interlacing does to you is, it creates flickering images.

Why this difference in case of NTSC and PAL? The main reason was that the frequency generator was derived from the sine wave of the AC signal. In USA and other places, where NTSC is prevelant, the AC frequency is 110~120V/60Hz whereas in case of PAL countries (Europe, Australia, Asia) it is 230~240V/50Hz.

Solution to interlaced scan
Early attempts to produce flicker free picture was to double the frequency from 50/60 Hz to 100/120 Hz. Thus the full picture could still be interlaced but shown twice as fast and thus reducing the flicker.

Enter Progressive Scan. Progressive or noninterlaced scanning is a method for displaying, storing or transmitting moving images in which all the lines of each frame are drawn in sequence and at once in a second. This is in contrast to the interlacing used in traditional television systems where only the odd lines, then the even lines of each frame (each image now called a field) are drawn alternatively.

Progressive scan (also known as: P-Scan) is used for most cathode ray tube (CRT) computer monitors, all LCD computer monitors, and most HDTVs as the display resolutions are progressive by nature. Some TVs, and most video projectors have one or more progressive scan inputs. Before HDTV became common, some high end displays supported 480p (480 vertical lines of resolution with progressive scan.) This allowed these displays to be used with devices which output progressive scan like progressive scan DVD players and certain video game consoles.

Progressive scan brought about the following advantages:

• Higher vertical resolution than interlaced video with the same frame rate.
• Absence of visual artifacts associated with interlaced video of the same line rate, such as interline twitter.
• No necessity in intentional blurring (sometimes referred to as anti-aliasing) of video to reduce interline twitter and eye strain.
• Offers much better results for scaling to higher resolutions than equivalent interlaced video, such as upconverting 480p to display on a HD-TV (more later).
• Frames have no interlace artifacts and can be used as still photos.

The above background is necessary to understand the CRT vs LCD vs Plasma debate.

Plasma TVs
A plasma display panel (PDP) is a type of flat panel display now commonly used for large TV displays (typically above 37-inch or 940 mm). Many tiny cells located between two panels of glass hold an inert mixture of noble gases. The gas in the cells is electrically turned into a plasma which then excites phosphors to emit light. Plasma displays are commonly confused with LCDs, another lightweight flatscreen display but with very different technology.

The advantage of the plasma TV is that it is very thin - typically just 3" deep. Plasma TV started with 480p resolution and then came up to 720p and with advent of HDTV, 1080p.

Plasma TV was oriented more towards the home theatre market and hence slowly started going from standard (4:3) format to widescreen (16:9) format. The 720p in widescreen format means a resolution of 1280x720 pixels. True high definition is 1080p or 1920x1080 pixels.

LCD TVs
LCD or liquid crystal display is a large amount of tiny liquid crystals that are held between two electrodes. When a charge is passed from one electrode to the other via the liquid crystals they react to the charge. This reaction causes light to be emitted which creates an image that you watch.

Other than that LCD TVs are very similar looking to plasma TVs but in looks only. They have their own differences and problems.

Plasma vs. LCD
Burn-in: Burn-in is a feature that causes an image to be permanently etched to the TV panel. For example, if you watch the same TV channel all day long, 365 days a year, the logo of the TV channel will be etched on the panel. When you change the channel, you can see it faintly on the panel. This is a possible problem with plasma but not LCD.

Thickness: LCD TVs are less thick than plasma TVs.

Contrast Ratio: This is a measure of the blackest black compared to the whitest white. Plasma TVs produce a brilliant contrast in comparison to LCD TV. This is because the LCD always "leaks" some light and hence black is never black.

Cost: For size to size, Plasma TV will be cheaper than LCD.

Viewing angle: LCD TVs have a viewing angle of up to 165°. The corresponding angle is 175° in case of LCD. This means that LCD will be less pleasing to watch from an angle.

Life span: 50,000 - 60,000 hours for LCD vs. 25,000 to 30,000 hours for Plasma.

Weight: LCD TV will be a lot lighter as compared to similar size plasma TV.

Which TV is right for me?
The first thing that you will immediately notice about CRT TV's are that they are far cheaper than Plasma or LCD TV's. This is so for two reasons. The first is that the new technology has cost a lot of money to develop so the makers of these televisions have to charge a premium. This price will drop (and is dropping) over time. The other reason is that a lot of marketing has gone into the new technologies so retailers are finding it hard to move CRT TV's. The bottom line if budget is a factor is that CRT is still the way to go.

One of the majors benefits of Plasma or LCD technology is that the television is a flat panel. It can be placed on a wall are does not take up space. If you have a small apartment or house then this might be a consideration.

CRT TV's have a wider viewing angle than Plasma/LCD. Thus if you are off center with a Plasma/LCD the vision might be distorted. Not so with CRT.

Plasma/LCD TV's have excellent resolution. Whereas a CRT TV might have a resolution of 480, Plasma/LCD can have up to 1080. They will also use the progressive scanning method as opposed to interlacing giving a more fluid image.

CRT technology has a better contrast ratio than Plasma/LCD. This means there will be more distinction between the blacks images on the screen. Again, this will make things stand out better in dark movies.

Plasma/LCD technology has a greater range of colors giving a vibrant picture as opposed to CRT.

If you wish to have a better viewing experience then Plasma will yield better picture because of the higher contrast as compared to LCD.

But clearly LCD are the latest technology. More money will be put into improving the deficiencies of the technology so it will improve over time. The price will also drop. If, however, you are on a budget and you do not plan to view HDTV in the near future you can't go past the low prices of good quality CRT televisions.

p/s. I have still not done enough justice to the article but as time moves on, I will. Meanwhile please post specific queries on this thread.

and please see this article: Buying guide to LCD TV

__________________

DZire

Added/converted my thoughts and questions in Red to your post itself....

This was good enough... Thx J4X.

just4kix

NTSC TV is actually 29.97 fps. This cannot be modified. Same holds true for PAL @ 25fps.

720i or 720p is also known as EDTV. In India, manufacturers are fooling the public by calling this HD-ready. There is no such thing as HD-Ready - either it is HD or it is not. However, 720p will give you better resolution than SDTV (480i or 480p).

Punch Farce

Isn't 720p HDTV?

Wikipedia says it is.

just4kix

720p is not true HD. It is higher definition than SDTV (480i). True HD is 1080i or 1080p.

itsmemad

I wanted to know whether my current CRT TV will work when HDTV transmission will take over in India?

just4kix

You don't have to really worry right now.

- HDTV, when it comes (and that could be 3/4 years away), will be transmitted in conjustion with SDTV. For instance, in USA, we get ESPN/HBO, etc. in SD as well as HD.
- HD will be available as separate channels in a spearate package and at additional cost
- In 3 or 4 years most people would be moving to HD LCD/Plasma TVs anyway because they would become much cheap. I expect that 42" HDTV will be available for Rs. 40K or less by then. So you may get rid of your CRT by then anyway.
- all SD and HD-Ready (720p) LCDs can automatically downscale HD input to their native definition.

DZire

That's what people suggest..
Wait with your CRT to be upgraded to LCD in a year's time.

Rameshjeee

LCD vs Plasma

Plasmas have higher viewing angle
Plasma TVs can render blacks far more effectively than LCDs. They have higher viewing angles, which means that if you’re sitting off to one side, the image quality won’t change.

They’re also better for fast-moving images (mainly sports and movies). And finally, Plasma TVs are more affordable than LCDs for the same screen size. You can go for LG’s 42” HD ready frame less Plasma (42PG61UR-TA) or Samsung’s 42” Series 4 Plasma (PS42A410C1) at under Rs 65,000. Whereas a 40” HD ready LCD will put you back by another Rs 5,000.

No full HD support
However, Pasmas are showing their age. Many are not full HD (the highest resolution available is 1920x1080 pixels) and not completely future proof. They’re still susceptible to 'burn in; -- the permanent etching of a static image on the inside of the screen when left on for too long.

Plus they have glassy, reflective screens and often get washed out in brightly lit rooms.

LCDs boast of longer life
LCDs are the newer technology. You’ll find a lot more full HD LCDs. They have longer lifespans, compared to the average plasma (Plasmas tend to get dimmer over the course of time).

LCDs also work better with video games. Plus the new generation LCDs like Samsung Series 6, LG Scarlet and Sony-Bravia X or W series can easily match or beat Pasmas in most departments

Look for sharper quality
Bottom line? First, work out your specific requirements and then do a side-by-side comparison of both technologies to see which one suit you better. The major things that might be deal-breakers for you after a demo will be the unnaturally sharp & bright images of an LCD or the reflectivity and washed out images of Plasma under bright light.

just4kix

Just as the plasma is suseptible to burn-in (etching), the LCD is also suseptible to dead or stuck pixels.

Dead and Stuck Pixels

Pixel defects for an LCD monitor are defined as one of two types: dead or stuck. Technically, both types of pixel defects are stuck pixels but it really deals with the electrical currents and the state of each pixel or sub-pixel.

A dead pixel is defined as a pixel or set of sub-pixels that has failed and is permanently in the off position. This condition means that the pixel will not let any light through. This can be observed as a dark or black spot on a brightly colored or white background.

A stuck pixel is defined as a pixel or sub-pixel that has failed and is permanently in the on position. This can be either with a single or multiple sub-pixels for a given pixel and is best observed on a dark or black background. A white pixel means all three sub-pixels have failed while a green, red or blue pixel means one of the sub-pixels has failed.

Sometimes the stuck pixel has only one or two colour failure. For example, if green and red fail, the pixel will appear as permanent blue.

DZire

Any Solution to this ?

just4kix

Solution to dead pixels, you mean?

Nope. Just as there is no solution to Plasma burn-in, there is no solution to dead pixels. Basically the pixel is dead and can no more function.

The only solution (so to speak) is buy a good brand with enough warranty on the display panel, yes, particularly the display panel. Use a stabilizer and spike guard.

newprouser

Haven't they started using Organic LED's for LCD monitor yet ?

Rep+

just4kix

Not heard about Organic LEDs. So can't say. Will check up.
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Update: Read about OLEDs. I do not think current LCD TVs are using OLEDs.

newprouser

Hmmm ok ... thx for info

Admin

Its a new thing and are a bit on the costly side... led lit lcd tv's
Sony has got them in India as well but the prices are sky high.

ag_prasun

the prblm with oled screens is that it is difficult to build a large size oled screen.a 32" oled screen would cost something in the range of 10lacs.

Punch Farce

Does that video look better in LCD or Plasma?

-F

just4kix

Plasma, most definitely. Because plasma will yield better blacks.

eruptionjoojo

Wanted to Know whether my LCD monitor is Full HD or not .......... ??


It's a DELL made SE198WFP ........ it's a 19' wide-screen LCD monitor

actually I got a Bit confused after reading the whole thread ........ anywhich ways while i checked the resolution available i.e. which i can set via windows display settings has various options i.e. :-

800*600 : 1024*768 : 1152*864 : 1280*600 : 1280*720 : 1280*768 : 1280*960 : 1280*1024 : 1440*900

The thing which is making me confused is that why can't i have a resolution of 1440*1024 ......... i'm asking this b'coz if there are 1440 and 1024 no. of pixels in the vertical and horizontal positions resp. then why there is no option of such kind or am i considering this in the wrong way ..... ??