Are laptop screens sized the way they are

displaylaptop

We've been discussing this in the Comms Room on Serverfault, and thought it might make a good question on SuperUser…especially if there's a clear answer. The hope is that it is a Good Subjective question.

Why do laptop screen sizes come in the fractional sizes they do instead of 11/12/13/14/15"? The most frequent I see advertised are 11.6", 12.5", 13.3", 14", 15.6". What's the reasoning behind it? keyboard size? ergonomics? resolution requirements? Most are LCD screens just like TV's, and yet TV's are advertised as whole numbers (19", 26", 46", etc.).

Looking at actual LxWxD dimensions on laptops doesn't really help since screen bezels vary in size.

For instance:

example 11.6" laptop dimensions =
11.55" x 8.50" x 1.27" — this is due to a rather large bezel.

Whereas my x1 carbon touch, 14" diagonal screen but dimensions = WQHD Touch: 13.03" x 8.94" x 0.55" (Front)-0.79" (Rear) — again bezel…if it could be edge to edge that would be different, and "normal math" would insist the actual "monitor size" was about 15.5", which it is if you include the bezel.

SO:

Are there actual equations/ratios/mathematical factors in determining screen sizes on a laptop that make certain sizes more common than others? Note I stated screen size (like the common 11.6", 13.3", 15.6", etc.) and not actual dimensions of the monitor lid itself.

TO HELP CLARIFY THE QUESTION:

I'm asking why those particular fractional sizes are so common? Look at HP, Lenovo, and Dell. They all tend to go with those screen sizes. Is it because it is what the consumers are used to seeing/using? Is it dictated by resolution requirements that dictate the screen size (meaning 11.6" works out resolution wise, but 11.7" doesn't)? Or is it something else? If you want to hone in on one: Something somehow determined that 11.6" was a good common screen size…I'm curious what that was.

Display sizes are determined primarily by how many displays will fit on one mother glass slab at the manufacturing plant.

The manufacturing plant starts off with a single slab of glass, onto which the displays will be manufactured. Mother glass sizes are mostly standardized in the industry, and are increasing:

Generation     Size (mm)                  Diagonal (inches)
1st            300 ×  400                    19
2nd            400 ×  500                    25
3rd            550 ×  650                    33
4th            680 ×  880 or 730 × 920       43 or 46
5th           1000 × 1200 or 1100 × 1300     61 or 67
6th           1500 × 1800                    92
7th           1900 × 2200                   114
8th           2200 × 2400                   128
9th           2400 × 2800                   145
10th          2850 × 3050                   164
10.5          2940 × 3370                   176
11th          3200 × 3600                   189


The larger a piece of mother glass is, the harder it is to work with, due to breakage. However, throughput is counted by number of working displays at the end of the line, and certain line processes take the same amount of time for a small piece of glass as for a large one. So to increase throughput, increase the mother slab and put more displays on it.

It doesn't make sense to create a manufacturing line for a single size of display. It makes more sense to create a manufacturing line that handles the same size mother glass slab, and just change the number of displays created from the mother glass slab based on the order requirements.

Since the manufacturing line glass isn't going to change in size, once you know about the size of the display you want, you can determine how many of them can fit onto one mother slab. If there's additional space, it makes sense to increase the size until you're using as much space on the slab as possible, without going over your size requirement.

So the 10th generation glass will make one 150" TV (which is only used at tradeshows simply to showcase the size of the mother glass a given factory can handle), or it will make nine 50" TVs. The second generation glass was able to make a nice 24" desktop display, or four 11.6" displays.

A more in-depth treatment of this can be found at Norm's Flat Panel. AUO has a nice interactive diagram that shows cutting patterns for a few sizes up to generation 8.5 glass. While I included 11th generation size, there are no plants currently operating at this size. Corning announced the world's first 10.5 generation glass substrate factory in December 2015, and it will take some time to build.

Keep a watch for the next tradeshow as other manufacturers demonstrate 150" TVs to show off their new 10th generation plants, and eventually 170" TVs as the first glass rolls off this new plant's line.