HurrdurrBlurr wrote: ↑11 Oct 2021, 12:01
Why is this monitor 23.8 and not 24.5?
These are Innolux panels rather than AUO, Samsung or LG -- they all have their different fabrications for the 24-25 inch class so what one makes in 24.5" a different panel factory makes in 23.8" -- like a fab line normally designed for 48 inch 4K panels versus 50 inch 4K panels. Mother glass is cut up to multiple smaller screens. Or how good your engineers are at miniaturizing the on-glass bezel driver circuits.
For example, mother glass designed for 50" HDTV or 75" HDTV screens can generate about 4x or 9x as many 24.5" screerns. (You still need 0.5" for the integrated circuits built into the edges of the glass). But a mother glass designed for 48" HDTV or 70" HDTV screens need to shrink the screen size to 23.8" to generate 4x or 9x as many screens. Sometimes they may shrink/enlarge the pixels using a different lithography mask, but usually it's about the same dpi and pixel size (4x 1080p displays from a 4K motherglass twice the diagonal measurement).
These are example numbers, just to give you the idea how you have to adjust the size a little to be able to cut out more screens from the same mother glass.
Different screen fabs operate differently, with different flexibilities, for reasons even unknown to me, except I know that manufacturing LCDs is a lot like manufacturing computer chips, in many ways.
It's dictated by glass wafer size. How many screens you can cut from a large motherglass, is like how many chips you can cut from a silicon wafer.
LCD Glass Are Just Merely Giant Glass Computer Chips
Different "mother glass" sizes are more optimally cut up to different sizes, one motherglass may give more panels if it's 23.8" instead of 24.5". Like the multiple chips on a silicon wafer, LCD glass is like a gigantic wafer that needs to be cut up!
Just like a silicon chip, a modern LCD screen is a fully lithographed integrated circuit with transistors -- a screen is just merely one giant glass chip with TFT (Thin Film Transistors) and has on-glass IC's at the bezels with a bunch of shift registers embedded in the glass edge so you don't need a 3840-wire ribbon cable for a 3840-column screen of a 4K panel. The same lithography creating the transistorized pixels are also used to build screen-refreshing-drivers for row-column refreshing of the thin film transistor active matrix screen.
LCD Screens Are Giant Transparent Write-Only DRAM Chips
Think of a modern LCD screen like a gigantic write-only DRAM chip, where a refresh cycle is writing data (pixel colors), and a single refresh cycle scanout is one whole-chip sequential write. It's like a DRAM chip that's gigantic in 24 inch instead of 0.5 inch size -- where you see every single bit and byte of memory (as visible colors) because the chip is transparent and you're seeing pixels directly.
There are also some additional benefits to these 23.8" panels, each panels have their pros/cons. I've found these 23.8" Innolux superior for strobe tuning for certain refresh rates.
Your mileage may vary (panel lottery effects, and batch by batch) but they have different characteristics that were rather interesting during strobe tuning.
OLEDs are also litographed too, not just LCDs. Except instead of transparent pixel valves, you've got directly light-emitting LED pixels.
Citations
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Canon Lithography Machine for Creating Displays
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Nikon Lithography Machine for Creating Displays
Lithography of screens are in micrometers rather than nanometers, so it's far cheaper per square inch of surface than a computer chip.
But some high-dpi modern smartphones has only recently finally packed more transistors per square millimeter than the first Intel 4004 microprocessor (10 micrometer)!
Yet you have to push an astonishing amount of data through them. You need to go
12 BILLION subpixels per second for 8K 120Hz with the math: 7680 x 4320 x 120(hz) x 3(rgb). Even 1080p 360Hz requires processing
2.24 BILLION subpixels per second at 1920 x 1080 x 360 x 3.
But even a 500dpi smartphone screen (50 micrometer pixels with ~10 micrometer subpixel transistors) is lithographed less dense than an IBM PC XT at 4.77 Megahertz (3 micrometer transistors or ~3000 nanometers). Now imagine an even lower density 72dpi computer display instead, and we've got lower transistor density and longer circuit microwires than the first CPU.
High-Resolution High-Refresh-Rate Screens Today Refresh More Bits Per Second Today Than DRAM Chips
If you consider all pixel color values of a 10bit 8K 120Hz panel with 10bit data written per subpixel -- then
your 12 billion pixels per second is 120 billion bits per second of bit-equivalent information. That's high end DDR4 DRAM territory. You're transmitting tens of gigabytes per second over a DisplayPort or HDMI cable continuously sustained permanently, while a single stick of the world's fastest RAM still peaks only briefly there only during sustained RAM writes that's completely sequential.
It's also yet another reason (amongst many, including artifacts-wise) why screens has stayed sequential scanout rather than random access pixels, because you can refresh more pixels faster with sustained sequential writes (which is what refresh cycles are). Modern screens now refresh faster than an average DDR4 memory stick if you include all possible information density crammed into a refresh cycle.
Driving pixels fast over long wire distances over low-density lithography is a losing battle sometimes but they've pulled off the impossible. The information density real-world refreshed into the pixels usually exceeds the real-world sustained benchmark world's fastest DDR4 memory sticks. Except the screen is just ONE chip, while a DDR4 memory stick contains multiple chips (usually 8).
It is a miracle the industry can get giant 70 inch and 80 inch screens refreshing faster than a whole pair of 8-chip memory stick running in dual-channel mode.
Even more a bigger miracle that you can buy these panels for just 3 figure prices. 1080p 240Hz for under $500? 4K 120Hz for under $1000? All here today. Fairy tale pie in the sky just a couple decades ago.
Hope this helps -- fascinating information about screen manufacturing being like the manufacture of chips, as it pertains to their odd sizes, their performance, etc.