Quick summary from the original Chinese text:
How is Sony Mobile able to manufacture a 4K phone?
Improvements in LED efficiency, new IC chips, and improved performance from Qualcomm's chips. Additionally, Sony's stake in display manufacturers allows it to have an easier time ordering new panels, enabling it to bring to the market the first 4K panel on a phone.
Why did they go with a 4K panel?
1080p and 4K content are mainstream, not 1440p.
Upscaling tech outline
There was news few days back that the Z5P ran at 1080p. This is actually due to Sony's new display technology. Z5P uses pixel complement upscaling to convert sub 4k display sources to 4k.
Under typical conditions, for power efficiency Sony will pick the 3rd and 4th methods (from
http://timg.eprice.com.tw/tw/mobile...0_3_4551_cfdec87f9206c4721fe8e32ede8f6d39.jpg) but it will change depending on situation.
In Album and Movies app the Z5P will either intelligently (fancy) upscale to 4K, but use (simple) pixel doubling upscaling for games and web browsing.
Z5 series display tech
Z5 series have fancy tech (Live Colour LED etc) but only Z5P has upscaling and wide viewing contrast technologies. It's not only the first mobile 4K panel, it is also a panel of the best quality.
Z5 series have PSR (Panel Self Refresh) - or what they're calling Memory on display.
Z5 series have very thin display stack, wherein making it thinner by 0.5mm allows an increase in battery capacity by > 20%.
The rest is showing off their software display enhancements, yadda yadda yadda (TRILUMINOS etc)
Audio enhancements
Z5 is the first with LDAC, and supports DSEE HX with spotifysupport. 3.5mm output support is enhanced with DAC decoding up to 192/24 versus Z3's 96/24. Z5 series also have automatic handset compensation (EQ) and supports noise cancelling with HiRes Audio (NC750 only for now it seems.)
LDAC improves Bluetooth streaming quality.
DSEE HX is an upscaling filter, that can be applied to both the stock Music app and Spotify.
How was 0.03s HybridAF attained.
New sensor with on chip PDAF (phase detection autofocus) pixels, with a wider lens, and OIS.
Sensor alternates between pure PDAF and PDAF+CDAF (contrast detection autofocus), but 0.03s assumes optimal light allowing PDAF only mode.
New HDR algorithms
Get better HDR pictures + comparison to competitors.
(I have no idea why is SteadyShot featured under HDR, it helps with HDR but it's more useful than HDR in many cases...)
Why is the Z5 series thicker? Fingerprint sensor.
The new camera system didn't cause it (it's the same thickness as prior systems), but rather due to the space requirements of the fingerprint sensor.