Quantcast

Samsung CRT-HDTV!

Nick_UK

Banned
welwynnick said:
....... The electron beam can never register exactly with any one particular phosphor "pixel" or line, and it doesn't try to. It is always set up so that the beam spot is bigger than the phosphors, and it always overlaps a few of them.
Well for a start, Nick, there isn't a single electron beam in a colour TV, there's three. There's an electron gun for each colour. And if you've ever done a "purity" adjustment on a CRT, you would know that the purpose of this is to make the beam from the red gun strike the red phosphors, not overlapping ones ! If you get this adjustment wrong, you can end up with some very dark pictures, because the beam is hitting the shadow mask, and not the phosphor dots.
 

Eiji

Member
welwynnick said:
Could be!
And it might also have HDCP on the HDMI input. I hope so.
The problem is, for the UK version of the TX-R3079WH, the WS32Z308P, Samsung removed the HDMI input and 1 of 2 component inputs and support for a 60Hz refresh rate. Quite sad really but Samsung have a chance at putting things right when they bring the newer model to the UK with hopefully all the features of its US counterpart.
 

Welwynnick

Well-known Member
Nick_UK said:
Well for a start, Nick, there isn't a single electron beam in a colour TV, there's three. There's an electron gun for each colour.
Yes, of course there are, and that is why there is a shadow mask. CRT pixels, unlike digital displays, are not addressable. You cannot aim the beams for a specific pixel. Whever the beams do strike, there will be a pixel of the right colour to illuminate. A "red" bem cannot strike a blue pixel because of the shaddow mask / eelctron gun geometry. And you cannot stop the beams from hitting the shadow mask. It might not sound very promising, but it does work.

Nick :)
 

Welwynnick

Well-known Member
Nick_UK said:
Yes, you are correct. In a colour CRT there are a fixed number of dots on the screen. These dots must act in a similar way to pixels on a plasma or LCD screen. However, the situation is often worse on a shadow mask CRT screen, because of the distance between the colour dots is higher than on a plasma or LCD.
Not true at all. Yes, there are a fixed number of RGB triads, but these do not define or restrict the resolution of the screen. That is limited by the electron guns and the drive electronics.

The dots (bars, or stripes, actually) behave like plasmas, but only in the sense that they are phospors, and they are red, greeen and blue. In a CRT, you can have several "dots" in one video pixel, or you can have more than one line or pixel illuminating each phosphor. It's an analogue display, not a digital one.

Distance between the colour dots is higher...? Are you sure about that? I don't believe that is true, but I've never seen it specified for a TV. I've got an SD 36"CRT and a 50" 1366x768 plasma, and I'm pretty sure the CRT dots are smaller. The plasma dots are at 0.81 mm pitch, which is small for a plasma - about 1.0 mm is typical. I'll go and have a look tonight.

Nick
 

Nick_UK

Banned
I think you'd better read this..........

Cheap Hi-Res TV : Forget It

I think you are talking TV and thinking PC. Yes, you can get some amazing dot-pitches on small CRT PC monitors, but as the size increases, so does the dot pitch and dot size. As you said, not many TV manufacturers quote dot-pitch, and it's for a very good reason. Most domestic CRT TV's struggle to resolve a 640 x 480 picture.

"Big nasty secret: There does not exist a colour CRT tube, whether shadow mask or aperture grille, TV or computer monitor, that can clearly display all 1920 horizontal pixels of full-res HDTV.

There are plenty of computer monitors that can accept input resolutions of 1920 by whatever, or higher, but none of them have enough phosphor units to actually clearly display them. TV tubes aren't even in the race."

 

Goose74

Novice Member
My Sony FW900 handles 1920x1200 quite nicely thanks! It can go up to 2560x1600 and looks stunning
 
D

Demon1

Guest
Just wanted to post this from the Samsung knowledge base.

Important: Although HDCP was initially developed to protect digital content sent through the DVI interface, it has also been applied to the newer HDMI digital interface. All devices with HDMI interfaces are HDCP compliant.


Important: All Samsung TVs with DVI connectors are HDCP compliant. All Samsung TVs with HDMI connectors are HDCP compliant.
 

Nick_UK

Banned
Goose74 said:
My Sony FW900 handles 1920x1200 quite nicely thanks! It can go up to 2560x1600 and looks stunning
And so it might, but it's not displaying all the pixels :suicide:
 

Welwynnick

Well-known Member
The pixels on these monitors are almost invisible to the naked eye, and they have a video bandwidth of 350 MHz - 60 times that of an ordinary PAL or NTSC TV, and more than any current PC video card can throw at them.

They can display 1920 pixels.
 

Kalos Geros

Active Member
I could see by looking at the Samsung 32Z308P at the mall, that its dot pitch didn't seem any higher than my 10-year old Samsung widescreen...and I have actually counted that my Samsung has 600 phosphor RGB clusters in vertical direction...I really wonder would 1080i be noticable with such a low dot pitch... :confused:
 

Nick_UK

Banned
welwynnick said:
The pixels on these monitors are almost invisible to the naked eye, and they have a video bandwidth of 350 MHz - 60 times that of an ordinary PAL or NTSC TV, and more than any current PC video card can throw at them.

They can display 1920 pixels.
Well, for a start Sony FW900's are 24" (22.5" viewable size) PC monitors not TV displays, which is what we were discussing - Samsung HD TV displays. Even so, if you do the math, you will find that it would not be possible to fit 1920 dots with a 0.23mm dot pitch across this size of screen.

The discussion is about the HDTV Slimline Samsung TV's, which are TV's, not PC monitors. Although the spec on these sets says that they have a "fine dot pitch", the spec conveniently omits to say exactly what the dot pitch is.
 

Welwynnick

Well-known Member
I think it’s my turn to be pedantic, now Yes, we are talking about Samsung TVs, but I didn’t raise the subject of the Sony monitors. Richard just suggested they couldn’t display 1920 x 1200 because someone with no accountability on some website made an ignorant sweeping generalisation.
Nick_UK said:
Even so, if you do the math, you will find that it would not be possible to fit 1920 dots with a 0.23mm dot pitch across this size of screen.
On the contrary, if you do the maths, you get:
Aspect ratio = 16:10
Diagonal = SQRT(256 + 100) = 18.87
Diagonal = 22.5” = 571.5mm
Horizontal = 571.5mm x 16/18.87 = 485mm
Resolution = 485/0.23 = 2107 pixels give or take a few
That squares with my eyeball estimate.
Pedantic, yes, but many people do believe what they read in this forum, like HMDI mandating HDCP etc.

By the way, I took some high–res close up photos of our 36” Sony TV with a ruler to get an estimate of the number of pixels. I’ll see if I can show some of them.

Horizontal resolution? Curiously enough, near as damn it to 852 pixels! About the same as an SD plasma, and sufficient for PAL.

Vertical resolution? Difficult to say – the pixels are in fact continuous vertical stripes. When the DRC video processing is set 100Hz (low res), there seems to be about 480 distinct horizontal lines. Not brilliant but fair enough. When the DRC is set to 50Hz (hi res), it’s not possible to distinguish individual lines or pixels. IIRC, DRC is supposed to double vertical resolution in this mode, so that is consistent with the horizontal scanning frequency of the 100Hz mode. We think the 50Hz mode looks much better. (And, incidentally, rather better than our 1366x768 plasma, scaler or no scaler.)

The point there, though, is that the “dots” do not limit the vertical resolution, at least. The more scans you take per field, the better the resolution. The phosphors simply display whatever they happened to be scanned with.
 

MikeK

Novice Member
I think it’s my turn to be pedantic, now Yes, we are talking about Samsung TVs, but I didn’t raise the subject of the Sony monitors. Richard just suggested they couldn’t display 1920 x 1200 because someone with no accountability on some website made an ignorant sweeping generalisation.
On the contrary, if you do the maths, you get:
Aspect ratio = 16:10
Diagonal = SQRT(256 + 100) = 18.87
Diagonal = 22.5” = 571.5mm
Horizontal = 571.5mm x 16/18.87 = 485mm
Resolution = 485/0.23 = 2107 pixels give or take a few
That squares with my eyeball estimate.
Pedantic, yes, but many people do believe what they read in this forum, like HMDI mandating HDCP etc.


Ah, just to play devil's advocate for a minute :), but does the FW900 not feature TV style variable stripe pitch, where it's 0.23mm in the middle of the screen, and 0.27mm towards the edges.

Given the width of 19.1in, this means that 1920 pixels is actually c.101dpi across the width of the screen. Now .23mm stripe pitch, gives c.110dpi, so you're OK there, but 0.27mm stripe pitch only gives c.94dpi, not quite enough for 1920.

How's that for pedantic :) :)

Of course if you assume c.6% overscan, then you only have to display 1805 pixels - which means you can actually do it, even at the edges, but then you aren't really displaying 1920 pixels anymore.


Bottom line is that it's not quite so simple to compare FPDs and CRTs on pixel/dot/stripe pitch alone. It's certainly an indicator though - and while there may be exceptions, I tend to agree that there are/will be few CRT TVs which can truly do 1920x1080.
However, that doesn't mean they won't look really good anyway with HD material - and ultimately that's really the bottom line, not the actual number of pixels!


By the way, I took some high–res close up photos of our 36” Sony TV with a ruler to get an estimate of the number of pixels. I’ll see if I can show some of them.

Horizontal resolution? Curiously enough, near as damn it to 852 pixels! About the same as an SD plasma, and sufficient for PAL.


Yes - in fact 720 stripes would be enough these days (assuming equidistant stripes :) and the interpretation of PAL timing to be 53.33usecs per active line, but this is another debate - 702 would be enough for a 52usec active line)


Vertical resolution? Difficult to say – the pixels are in fact continuous vertical stripes. When the DRC video processing is set 100Hz (low res), there seems to be about 480 distinct horizontal lines. Not brilliant but fair enough. When the DRC is set to 50Hz (hi res), it’s not possible to distinguish individual lines or pixels. IIRC, DRC is supposed to double vertical resolution in this mode, so that is consistent with the horizontal scanning frequency of the 100Hz mode. We think the 50Hz mode looks much better. (And, incidentally, rather better than our 1366x768 plasma, scaler or no scaler.)


You'd like to think that there would be 576 lines viewable for a large PAL TV (not inc overscan of course) - however, as your experience may show, the reality is often a little different to what we may intuitively expect.
Of course some of these modern processing options can greatly complicate things, esp when the manufacturer is a bit vague about they really do!
 

Welwynnick

Well-known Member
MikeK said:

Ah, just to play devil's advocate for a minute :), but does the FW900 not feature TV style variable stripe pitch, where it's 0.23mm in the middle of the screen, and 0.27mm towards the edges.
That's absolutely correct. If you take an average of 0.25mm, then you do end up with 1920 pixels. Some specs say it can accept 2300 or 2500 horiz res, but when I tried that, it didn't look right. Sony recommends 1920x1200, and with good reason. I'm happy that's it's real resolution.

Whether a CRT HDTV can actually resolve 1920 x 1080 is another matter. I've heard several people say they can't, and I wouldn't be surprised if that applied to the Samsungs, too. At least they accept 720p and 1080i and display them both at (near) native, which probably means they would look very good. It's good news that Samsung sets with DVI/HDMI take HDCP, I just hope the UK sets will have them. HD by YUV only is too much hard work.

Nick
 

Nick_UK

Banned
welwynnick said:
On the contrary, if you do the maths, you get:
Aspect ratio = 16:10
Diagonal = SQRT(256 + 100) = 18.87
Diagonal = 22.5” = 571.5mm
Horizontal = 571.5mm x 16/18.87 = 485mm
Resolution = 485/0.23 = 2107 pixels give or take a few
That squares with my eyeball estimate.
Pedantic, yes, but many people do believe what they read in this forum, like HMDI mandating HDCP etc. .
Pedantic ? Yes. Correct ? NO !

Because you don't understand what "dot pitch" is ! Dot pitch is the distance between pixels, not the diameter of the pixels !

Of course you could fit 2107 pixels across a 485mm wide screen if the dot diameter was 0mm, but even if your pixel was 0.2mm diameter, you're only going to fit about 1000 into that space. Sorry to disillusion you, but you should make sure you understand what the terms mean before you make "sweeping generalisations" ! ;) :rolleyes:

http://www.helpwithpcs.com/jargon/dot_pitch.htm
 

Eiji

Member
While were on the subject of dot pitch, Samsung's WS-32Z308P 1080i HD CRT has a dot pitch of 0.77mm according to some Dutch folks who have been 'observing' the set.

Here is a picture one of the members took:
 

Attachments

Nick_UK

Banned
Are you sure they are not getting confused with the definition of "dot pitch"? It is one of the most confused terms - lots of people think it refers to the actual size/diameter of the pixels, but it doesn't.
 

Welwynnick

Well-known Member
Eiji83 said:
While were on the subject of dot pitch, Samsung's WS-32Z308P 1080i HD CRT has a dot pitch of 0.77mm according to some Dutch folks who have been 'observing' the set.
Well that is interesting. I took some pictures like that of my 36" TV - there should be one attached - and counted 112 pixels in 100mm, giving a pixel pitch of 0.89mm, or very close to 36/32 times the size of the Sammy. That suggests they have similar number of pixels - about 850 horizontally. You would expect a 1080i set to have more than twice that number. I was led to believe that they wouldn't actually resolve 1920 horizontally, but I didn't think they would fall that short.
 

Welwynnick

Well-known Member
Nick_UK said:
Pedantic ? Yes. Correct ? NO !
Because you don't understand what "dot pitch" is ! Dot pitch is the distance between pixels, not the diameter of the pixels !
OK, hands up all those people that think that Nick UK is wrong. The reference you gave just said "the distance between the pixels". That's rather loose, but it certainly didn't mean the gap between them. The word "pitch" is widely used to refer to the distance between periodically recurring items, such as threads on a screw, bricks in a wall...., many spatially repeated events.

In each case, though, the pitch is the size of the item plus the gap in between - it is the distance between the same points in the recurring items. In our case, it is the distance between, say the centreline of the red phosphor in one pixel and the centreline of the red phosphor in the next pixel. That is what pitch means.

To prove my point, I put a ruler up against my monitor, and counted 40 pixels in a centimetre - and I can post a picture to prove it tonight should that be necessary. So a little less shouting down of other people when you don't know what you are talking about, if you please! :nono:

Nick
 

MikeK

Novice Member
You'd also have to take account of where on the screen that ruler is sitting - it's very common for the dot/stripe pitch on TV sets to be larger near the edges than it is in the centre.

Dot-pitch does not refer to the inter-dot gap alone - it refers to the distance (usually measured diagonally) between the centre of one dot, and the centre of the same coloured dot in the adjacent triplet. Hence it includes BOTH the diameter of the dot itself AND the gap!
Strip pitch (for aperture grille CRTs) is similar, but is measured horizontally.
Depending on the screen, typically to compare a dot and stripe pitch, you'd take around 10% off the dot-pitch figure - so a .23mm stripe pitch would be about equal to a .25mm dot-pitch - roughly speaking!
 

Nick_UK

Banned
welwynnick said:
.......... So a little less shouting down of other people when you don't know what you are talking about, if you please! :nono:
Ahh, like last week, when you were completely convinced that plasma screens were scanned like CRT's ? (Until a few people put you straight, of course). :oops:
 

silkyandy x

Novice Member
Interesting discussion guys. My questions is if the crt tv can do 1080I shouldnt it be able to do 720p anyway? I thhought that CRT's did not have any fixed pixels and was capable of displaying pratically any resolution upto the maximum resolution?
 

Welwynnick

Well-known Member
Nick_UK said:
Ahh, like last week, when you were completely convinced that plasma screens were scanned like CRT's ? (Until a few people put you straight, of course).
No. Not , not completely convinced, and not like CRTs. Just curious, and hoping to contribute to a discussion.

What I said was: "Well I distinctly recall reading a very authoritative source saying that they DO scan the frame progressively, a line at a time, just not a pixel at a time like CRTs."

And in my second post I had the good grace (!) to say that I had learned something new. I then asked how a plasma could control all of it's pixels independantly and simultaneously when every pixel in a row shares the same scan and sustain electrodes, and every pixel in a column shares the same address electrode. There were no specific replies, and I would genuinely still love to know the answer. Anyone?

Best regards, Nick :)
 

Welwynnick

Well-known Member
silkyandy x said:
Interesting discussion guys. My questions is if the crt tv can do 1080I shouldnt it be able to do 720p anyway? I thhought that CRT's did not have any fixed pixels and was capable of displaying pratically any resolution upto the maximum resolution?
Not necessarily. Scan lines can go anywhere they like with a CRT (unlike digital displays), but there are other constraints on what a CRT can display: screen resolution, input bandwidth, vertical refresh rate and horizontal refresh rate. The latter is a restriction for 720p, because the line scanning frequency is relatively high - approx 45kHz: around half again as high as 480p or 1080i. That's a bit more expensive to engineer properly, so manufacturers avoid it if they can get away with it. That's unfortunate, because cross-conversion from 720p to 1080i doesn't usually work very well. The newer Samsungs appear to accept and display 720p properly, which is quite a big step forwards.

Nick
 

cerebros

Active Member
silkyandy x said:
Interesting discussion guys. My questions is if the crt tv can do 1080I shouldnt it be able to do 720p anyway? I thhought that CRT's did not have any fixed pixels and was capable of displaying pratically any resolution upto the maximum resolution?
Unfortunately the resolution that can be drawn will depend on the scanning frequency the set electronics support.

Based on 50Hz refresh, 1080i requires a frequency of 27KHz (540 lines x 50 fields), whereas 720p requires a frequency of 36KHz (720 lines x 50 frames). So just becuase a set can draw 1080i, doesn't mean its electronics support the higher scan rate required for 720p
 

Welwynnick

Well-known Member
Bang on.
But the frequencies are a bit higher than that because of the lines that are broadcast or stored, but not displayed - teletext, frame sync, etc.
 

Stephen Neal

Well-known Member
cerebros said:
Unfortunately the resolution that can be drawn will depend on the scanning frequency the set electronics support.

Based on 50Hz refresh, 1080i requires a frequency of 27KHz (540 lines x 50 fields), whereas 720p requires a frequency of 36KHz (720 lines x 50 frames). So just becuase a set can draw 1080i, doesn't mean its electronics support the higher scan rate required for 720p
Correct logic - wrong maths.

CRT TVs actually operate at the full, not just the active, line rate. Therefore a standard def TV set runs at 625 lines, not 576, so the scanning rate is 625x25, or 312.5x50.

For 1080i, the total number of lines is 1125 (remember that Japanese standard?!) and for 720p the total number of lines is 750.

The numbers are thus (ignoring 59.94 vs 60 in NTSC) :

480/60i = 525/60i = 262.5 x 60 = 15.75 kHz
480/60p = 525/60p = 525 x 60 = 31.5 kHz
1080/60i = 1125/60i = 562.5 x 60 = 33.75 kHz
720/60p = 750/60p = 750 x 60 = 45kHz

576/50i = 625/50i = 312.5 x 50 = 15.625 kHz
576/50p = 625/50p = 625 x 50 = 31.25 kHz
1080/50i = 1125/50i = 562.5 x 50 = 28.125 kHz
720/50p = 750/50p = 750 x 50 = 37.5 kHz

As you can see, 480/60i and 576/50i are very close - which is why it is easy to make TVs that can cope with both PAL and NTSC (or 480/60i and 576/50i component/RGB) signals.

Similarly 480/60p, 576/50p, 1080/60i and 1080/60p are all pretty close - between 28.125 kHz and 33.75 kHz (though 1080/50i is further away than the other three) so again it is easy to make displays that can cope with all of these signals natively. (480/60i and 576/50i are usually converted to either 480p/576p or 1080i prior to display)

720/50p and 720/60p are significantly different to 1080/50i and 1080/60p (as well as 480p and 576p) so it requires more engineering to create a display that copes with both natively - it is kind of like multi-sync vs fixed sync monitors.
 

Kalos Geros

Active Member
Stephen Neal said:
For 1080i, the total number of lines is 1125 (remember that Japanese standard?!) and for 720p the total number of lines is 750.
Everything you said is spot on except: I can't understand why for example 1080 mode needs additional lines (1125 cumulative) when it actually doesn't need to carry any additional analog information beside picture. Dvd players can do DA conversion but they also need NO extra data to be sent to the display. Or is it a left-over from times when they thought HD would initially be all-analog and additional data would be transmitted via the additional lines...????

About dot pitch: it is the distance between same-colored dots in two neighbouring RGB clusters...the dot is NOT each of R, G, or B elements, but a cluster made up of all three of them...
 

Stephen Neal

Well-known Member
Kalos Geros said:
Everything you said is spot on except: I can't understand why for example 1080 mode needs additional lines (1125 cumulative) when it actually doesn't need to carry any additional analog information beside picture.
You have to separate in your mind the digital storage requirements, using frame stores, from the analogue display systems that CRT displays are still based around.

The CRT is based around a flying spot travelling across a tube.

In the 625/50 video system each TV line lasts 64us. 52us of this time it is tracing active picture, but there is 12us between the end of one 52us active line and the start of the next. This is used in the video signal as a sync pulse (and for chroma burst in composite PAL 50) but it is also a requirement to allow the electron beam to quickly "fly back" from the right hand side of the screen to the left. The magnetic deflection coils and drive systems can't move the electron beam instantly, they need time to do this - and they have 12us to do it.

Similarly when tracing from the top of the screen to the bottom of the screen, they have to trace 287.5 (rounded to 288 these days) active lines in the field, and then the beam has to fly from the bottom of the screen to the top, and it is allowed 24.5 lines to do this.

Sure it would be possible to not deliver the signal from the source to the display using an 1125 or a 750 line standard, and in fact some DVI-D systems exploit this by reducing the amount of horizontal and vertical blanking to increase the proportion of active video carried. This is possible as DVI displays are less likely to be CRT based these days, and LCDs don't have the same flyback issues.

Given that we were discussing why the actual scanning systems that drive the electron beam deflection in a tube are easy to use for both 480p and 1080i but not for 720p - it was pertinent to mention the actual frequencies involved in the tube scanning.

Sure you could use a different line-scan rate for the video interconnects, and clock a 1080 line total signal into a 1080 line frame store, which you then clocked out as an 1125 line signal for CRT scan purposes - but why make life more difficult? Such interconnects would also mandate every CRT display contained a 1080i frame-store, whereas a 480p or 1080i only CRT doesn't currently.

Dvd players can do DA conversion but they also need NO extra data to be sent to the display. Or is it a left-over from times when they thought HD would initially be all-analog and additional data would be transmitted via the additional lines...????
CRTs still require time to fly back from right to left and from bottom to top...

DVDs still output 480i as 525i, and 576i as 625i on their analogue video outputs for this reason, and set top boxes etc. output 1080i as 1125i and 720p as 750p - at least in analogue component HD terms.

It is important to remember that the 1080/60i standard is only a slight tweak of the original Japanese HiVision 1125i/1030-1050i system that has been with us for well over 15 years. (The BBC shot a drama co-produced with NHK using it in 1989, and there is footage of the 1984 LA Olympics using it...) As such it was originally an entirely analogue system - from camera to VTR to TV display.
 

Trending threads

Latest News

Philips OLED burn-in solution is 95 percent effective
  • By Andy Bassett
  • Published
Philips TVs with HDMI 2.1 and Dolby Vision IQ due in time
  • By Andy Bassett
  • Published
Sonos clarifies product update and recycling position
  • By Andy Bassett
  • Published
Philips 4th Gen P5 processor adds AI for more realistic images
  • By Andy Bassett
  • Published
LG regards HDR10+ as unnecessary
  • By Andy Bassett
  • Published
Top Bottom