LCD TVs

crutschow

Joined Mar 14, 2008
28,161
The pixel pitch varies with the screen size and the resolution of the display.
For example a 4k TV has 3840 x 2160 pixels.
If the TV screen were 50 inches wide than the pitch would be 3840 / 50 = 76.8 ppi
 

bertus

Joined Apr 5, 2008
21,667
Hello,

@crutschow , is the size of a TV not given as the diagonal of the screen?
Then the PPI will be diffrent as the side is smaller as the diagonal.

Bertus
 

MisterBill2

Joined Jan 23, 2018
9,793
Given that the pixels are cloe to square the pitch will be close to the same, vertical and horizontal.and possibly close to some published number. BUT the actual picture can be no better than what is being sent to the TV input connection. And once you have the set you are stuck with whatever pitch it came with. Getting the bigger screen does not buy you much better resolution.
 

crutschow

Joined Mar 14, 2008
28,161
is the size of a TV not given as the diagonal of the screen?
Then the PPI will be diffrent as the side is smaller as the diagonal.
Yes, the screen size is normally given as the diagonal since that gives the largest number for advertising purposes.
But if you notice, I used the width of the screen and the number of horizontal pixels, not the diagonal in my calculations.
For a 50" width, the diagonal would be about 57.4"
 
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s14rs4

Joined Sep 15, 2016
73
Yes, the screen size is normally given as the diagonal since that gives the largest number for advertising purposes.
But if you notice, I used the width of the screen and the number of horizontal pixels, not the diagonal in my calculations.
For a 50" width, the diagonal would be about 57.4"
Just to but in, the diagonal measurement is historical, the original cathode ray tubes were circular and the the dimension given was the outer diameter of the glass tube. The maximum picture size was limited by the diagonal, which would be much smaller.
 
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MisterBill2

Joined Jan 23, 2018
9,793
Just to but in, the diagonal measurement is historical, the original cathode ray tubes were circular and the the dimension given was the outer diameter of the glass tube. The maximum picture size was limited by the diagonal, which would be much smaller.
It seem that some set makers use a stretchy tape when measuring that diagonal, and they round up to the next whole inch. And sometimes they will add the qualifier word "class" so that a 49.4 inch screen is a "50 inch clas" sized screen.

Crutschow does have it correct, though. The pixel pitch i based on the width, not on the diagonal.
 

s14rs4

Joined Sep 15, 2016
73
It seem that some set makers use a stretchy tape when measuring that diagonal, and they round up to the next whole inch. And sometimes they will add the qualifier word "class" so that a 49.4 inch screen is a "50 inch clas" sized screen.

Crutschow does have it correct, though. The pixel pitch i based on the width, not on the diagonal.
I suspect that screen manufacturers probably work with metric dimensions anyway. :)
 

crutschow

Joined Mar 14, 2008
28,161
Just to but in, the diagonal measurement is historical, the original cathode ray tubes were circular and the the dimension given was the outer diameter of the glass tube. The maximum picture size was limited by the diagonal, which would be much smaller.
They masked the top and bottom of the round screen but left the sides curved to give a somewhat rectangular picture (below), so the diagonal was the same as the width.
When they developed more or less rectangular tubes, they went to measuring the diagonal.

1625589332826.png
 
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