Philips LCD HDTV with 1,000,000:1 to be released this year!

[Nielo TM]

A 47” 1080p Philips LCD with LED backlighting will be releases this year according to engadget. So if you have some large amount of cash to burn, here’s your chance.







PS: I don’t see the point of releasing SED, FED or the next-gen PDP anymore lol (unless they can be manufactured cheaply)

[Tejstar]

Interesting - it looks like that Sharp set has some competition! Would love to see one in the flesh!

[NicolasB]

Originally Posted by Nielo TM

The ultra high contrast ratio is achieved by having dedicated LED backlighting for each individual pixel.

I don't see any reference to 1 LED per pixel in the article you link to - do you have a source for that? If it really does have 1 LED per pixel that would be an amazing advance.

[DanDT]

Originally Posted by NicolasB

I don't see any reference to 1 LED per pixel in the article you link to - do you have a source for that? If it really does have 1 LED per pixel that would be an amazing advance.

This set doesn't have 1 LED for each pixel, that would be totally overkill and a waste of resources at the moment. Plus, i don't even think it's possible to release a set this year like that - the technology is just not there. It most likely has a array of LEDs at much lower resolution than the real LCD's resolution, which is really more than enough and will give much, MUCH better results than normal LCDs anyway.

[Dave163]

Can I ask a really stupid question? Rather than having an array of hundreds of switchable LEDs behind the LCD screen instead of a conventional backlight, why not have a conventional backlight but mount a second LCD screen between the backlight and the main LCD screen, immediately behind the main LCD screen (ie the one with colour pixels)? The secondary screen would need only black-and-white pixels capable of a greyscale, and they could be much larger than the tiny colour pixels. The purpose of the secondary screen would be to adjust the amount of backlighting at localised areas of the screen to improve the contrast ratio, ie letting all the light through in light areas and blocking off most of the light in dark areas. I'd have thought that would give pretty much the same result as having an array of dimmable white LEDs, but at much reduced cost. Can I patent the idea???
Dave

[NicolasB]

Originally Posted by Dave163

Can I ask a really stupid question? Rather than having an array of hundreds of switchable LEDs behind the LCD screen instead of a conventional backlight, why not have a conventional backlight but mount a second LCD screen between the backlight and the main LCD screen, immediately behind the main LCD screen (ie the one with colour pixels)? The secondary screen would need only black-and-white pixels capable of a greyscale, and they could be much larger than the tiny colour pixels. The purpose of the secondary screen would be to adjust the amount of backlighting at localised areas of the screen to improve the contrast ratio, ie letting all the light through in light areas and blocking off most of the light in dark areas. I'd have thought that would give pretty much the same result as having an array of dimmable white LEDs, but at much reduced cost. Can I patent the idea???
Dave

I think part of the reason for using LED backlights is that they're not white - there are separate red, green and blue ones. This is (I believe) what allows LED-backlight devices to achieve a much wider colour gamut than conventional LCDs: the standard backlight tends not to be very well balanced in terms of red, green and blue components, and it's trickier to get the filters the right colour.

If all of the light hitting the LCD panel is already within the correct R, G and B bands, that makes life much simpler. It also means you can (for example) dial down the blue component of the backlight while leaving the red and green components at full brightness, so you have rather more precise control over the output.

In your proposed setup you'd also have to ensure that the light coming through the back grid had the correct spectral characteristics (e.g. the same balance of red and blue) at all brightness levels, which would be quite a trick. And you'd have alignment problems: how do you ensure that all of the light from one cell in the rear grid only strikes the appropriate front pixels and nothing around them? The only way to do this would be to make the lightly highly collimated, which would reduce your viewing angle almost to zero.

It'd also be expensive, of course.

I think a more interesting question is: is anyone currently developing an LCOS device using LED lighting? That would kick *rse.

[Nielo TM]

I don’t see how that level of contrast ratio can be achieved without having very deep blacks.

[Dave163]

Originally Posted by NicolasB

I think a more interesting question is: is anyone currently developing an LCOS device using LED lighting? That would kick *rse.

Thanks Nicolas!

To answer your question, LG are taking a twin-track approach to projection technology: on the one hand they have a LCOS rear-projection TV:
http://www.cinenow.com/uk/view-press-release-312.html

On the other hand they have an LED-lit DLP projector:
http://www.aboutprojectors.com/news/...led-projector/

No mention on the lamp source for the RPTV, so presumably it's a conventional bulb. But if they stuck a white LED source into it, it would be really interesting to compare that to a DLP.

Hard to know which would be better - I can't stand DLPs due to rainbows, but if the new Samsung RPTVs have fast enough colour switching to exceed what the eye can perceive, you have the plus that there's only one microarray so no risk of misconvergence. On the other hand, with LCOS you have no screendoor, but risk of misconvergence of the three colour panels. I'd heard that DLP has better contrast than LCOS though I'm really impressed by the new Sony LCOS (can't afford one though!) All said, I prefer the "look" of DLP to LCD but can't stand the rainbows.

Thoughts?

[NicolasB]

Originally Posted by Dave163

No mention on the lamp source for the RPTV, so presumably it's a conventional bulb. But if they stuck a white LED source into it, it would be really interesting to compare that to a DLP.

Assuming it works the same way as existing LCOS devices, i.e. that it uses three separate LCOS panels, it would seem to be a particularly silly idea to use white LEDs. It would make more sense to use red LEDs for the red panel, green for green, and blue for blue.

Originally Posted by Dave163

Hard to know which would be better - I can't stand DLPs due to rainbows, but if the new Samsung RPTVs have fast enough colour switching to exceed what the eye can perceive, you have the plus that there's only one microarray so no risk of misconvergence.

I remain suspicious about the alleged rainbow-free nature of LED-powered DLP devices. You're still reducing the problem rather than eliminating it: the eye will move less between successive sub-frames, but it will still move, and the inages still won't precisely line up on the retina. There's also the question of how fast the actual DLP mirrors can switch.

Originally Posted by Dave163

On the other hand, with LCOS you have no screendoor, but risk of misconvergence of the three colour panels. I'd heard that DLP has better contrast than LCOS though I'm really impressed by the new Sony LCOS (can't afford one though!) All said, I prefer the "look" of DLP to LCD but can't stand the rainbows.

DLP traditionally has very good ANSI contrast ratio, but I believe that in terms of absolute black level and shadow detail (i.e. differing levels of shadow in an overall-dark scene) LCOS has superior contrast to DLP; doubly so in a dynamic-iris system. (I'm actually not sure how LCOS performs on ANSI contrast tests; most oif the "DLP has the best ANSI contrast" claims date back to before LCOS became a serious contender).

[sandstheman]

Originally Posted by Nielo TM

I don’t see how that level of contrast ratio can be achieved without having very deep blacks.

The way they achieve it is by switching off clusters of LEDS in pure black areas. The problem with current backlight setups is that the backlight is constantly on and they depend on the LCD being able to shut out most of the light.

Although i would take the figures with a pinch of salt, as you can have a display that outputs 0 cd/m2 at it's darkest and 1 cd/m2 at it's brightest, not very bright but by the virtue that it is outputting 0 for black it technically has an infinite contrast range.

For a good explanation have a read of this article, it's pretty much an identical principle:

http://www.bit-tech.net/hardware/200...hdr_edr/1.html

[Nielo TM]

Thx for site, it explains a lot. Anyway, I am aware of manufactures overstating the contrast ratio of the display by increasing the brightness, contrast and backlight to maximum (e.g. LCD 600cd/m2 and PDP 1200cd/m2) and measuring the white level, then lowering the contrast, brightness and backlight to measure the black level (LCD 0.3cd/m2 and PDP 0.2cd/m2). By doing so, they will achieve very high contrast ratio (LCD, 600 divided by .03 = 2000:1 and 1200 divided by 0.2 = 6000:1 for PDP).

I'm just gonna wait for OLED lol

PS: Hope the warranty covers single dead LED, unlike the pixel policy lol

[DanDT]

Originally Posted by Nielo TM

Thx for site, it explains a lot. Anyway, I am aware of manufactures overstating the contrast ratio of the display by increasing the brightness, contrast and backlight to maximum (e.g. LCD 600cd/m2 and PDP 1200cd/m2) and measuring the white level, then lowering the contrast, brightness and backlight to measure the black level (LCD 0.3cd/m2 and PDP 0.2cd/m2). By doing so, they will achieve very high contrast ratio (LCD, 600 divided by .03 = 2000:1 and 1200 divided by 0.2 = 6000:1 for PDP).

I'm just gonna wait for OLED lol

PS: Hope the warranty covers single dead LED, unlike the pixel policy lol

On LED LCDs, there would be no point because when showing the same picture at high contrast, some of the LEDs will be completely OFF, giving pure black, and some LEDs in another area of the screen will be ON, giving full brightness. And the areas in between will have LEDs which are dimmed.

These sets will give picture quality that is SO above current LCDs that it will hardly matter what the real constrast ratio is. I do agree that this new trend of 1,000,000:1 CR's is pure marketing. Mathematically, the sets would have "indefinite" contrast ratio.

[sandstheman]

Originally Posted by NicolasB

I think part of the reason for using LED backlights is that they're not white - there are separate red, green and blue ones. This is (I believe) what allows LED-backlight devices to achieve a much wider colour gamut than conventional LCDs: the standard backlight tends not to be very well balanced in terms of red, green and blue components, and it's trickier to get the filters the right colour.

If all of the light hitting the LCD panel is already within the correct R, G and B bands, that makes life much simpler. It also means you can (for example) dial down the blue component of the backlight while leaving the red and green components at full brightness, so you have rather more precise control over the output.

In your proposed setup you'd also have to ensure that the light coming through the back grid had the correct spectral characteristics (e.g. the same balance of red and blue) at all brightness levels, which would be quite a trick. And you'd have alignment problems: how do you ensure that all of the light from one cell in the rear grid only strikes the appropriate front pixels and nothing around them? The only way to do this would be to make the lightly highly collimated, which would reduce your viewing angle almost to zero.

It'd also be expensive, of course.

I think a more interesting question is: is anyone currently developing an LCOS device using LED lighting? That would kick *rse.

I don't think these panels will be using arrays of RGB led's as white LED's themselves have a much better colour GAMUT than the flourescent backlights that are currently used, but also the problem of getting LED's small enough and powerful enough and running cool enough to have 3 per pixel has not really been solved yet. I would say in all the cases of the new LED LCD TV's they will be using arrays of White LEDs (which are actually Blue LED's with a phosphor coating to create white: http://dansdata.blogsome.com/2006/12...-diffraction/). Again if you have a read of the article i linked in an earlier post you'll see an outline of how this is supposed to work and the related heat issues

[NicolasB]

Originally Posted by sandstheman

I don't think these panels will be using arrays of RGB led's as white LED's themselves have a much better colour GAMUT than the flourescent backlights that are currently used, but also the problem of getting LED's small enough and powerful enough and running cool enough to have 3 per pixel has not really been solved yet.

There's no way of having an individual white LED for each pixel either. Your previously-linked article, for example, describes an array of 45x31 LEDs driving am entire hi-def screen. (This, incidentally, means that the ANSI contrast ratio would be no better than that of current LCD displays - only the on/off value would be improved).

Originally Posted by sandstheman

I would say in all the cases of the new LED LCD TV's they will be using arrays of White LEDs

You may well be right. I imagine DLP displays will use three colours of LEDs, though, lit in sequence (for a single-chip device) or lighting three separate panels (for a 3-chip device). That would also be the logical arrangement for an LED-driven LCOS display.

[sandstheman]

Originally Posted by NicolasB

There's no way of having an individual white LED for each pixel either. Your previously-linked article, for example, describes an array of 45x31 LEDs driving am entire hi-def screen. (This, incidentally, means that the ANSI contrast ratio would be no better than that of current LCD displays - only the on/off value would be improved).

You may well be right. I imagine DLP displays will use three colours of LEDs, though, lit in sequence (for a single-chip device) or lighting three separate panels (for a 3-chip device). That would also be the logical arrangement for an LED-driven LCOS display.

I agree, they won't have an LED per pixel period, but i don't think they'll have as small an array as 45x31 either, LED's are small enough to have an array larger than that