# LCD TVs

#### biferi

Joined Apr 14, 2017
231
Do lcd TVs have a Pixel Pitch or are the Pixels so close they do not even Say?

#### DickCappels

Joined Aug 21, 2008
8,170
Yes, they have pixel pitch.

#### crutschow

Joined Mar 14, 2008
28,557
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

#### biferi

Joined Apr 14, 2017
231
Well I have the TCL 75R635 TV and it is 4. K and 75 Inches.
What is my PPI?

#### bertus

Joined Apr 5, 2008
21,764
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
10,587
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
28,557
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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#### crutschow

Joined Mar 14, 2008
28,557
Well I have the TCL 75R635 TV and it is 4. K and 75 Inches.
What is my PPI?
A 75" diagonal TV has a screen width of about 65.4".
The PPI would then be 3850pixels / 65.4" = 58.9 pixels / inch.

#### biferi

Joined Apr 14, 2017
231
Well my LCD TV is 75 Inches.
So if I do 3840 Divided by 75 will this give me my Pixel Pitch?

#### crutschow

Joined Mar 14, 2008
28,557
Well my LCD TV is 75 Inches.
Did you not read my post #8?
As I said, 75 inches is the diagonal measurement.
The width is thus about 65.4" and the number of horizontal pixels is 3840, so the pixel pitch is 3840 / 65.4 = 58.9 ppi.

#### 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
10,587
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.

#### MisterBill2

Joined Jan 23, 2018
10,587
I suspect that screen manufacturers probably work with metric dimensions anyway.
Just think about the confusion if they start claiming diagonal sizes in millimeters!! Really impressive big numbers.

#### s14rs4

Joined Sep 15, 2016
73
Just think about the confusion if they start claiming diagonal sizes in millimeters!! Really impressive big numbers.
An easy way to increase the size of the picture, at no extra cost, is to move your chair closer.

#### crutschow

Joined Mar 14, 2008
28,557
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.

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