Nikon Z system patent

For those that are interested, I finally found the major patent for the Z system. It's possibly been located before - but I haven't seen it, I hope it's useful.
The communications system is interesting. The main channel is a conventional duplex SPI operating at 8MHz, through which the command interface runs driven by the camera, as might be expected. There's also a 'hot-line' channel a simplex synchronous channel running from lens to body, which is driven by the lens. The lens using this channel to send the camera information at 1ms intervals, describing for example 'a position of the focusing lens, a position of an image blur correction lens, and a position of an aperture'. What an 'image blur correction lens' is I'm not sure. It sounds like in lenses with two focussing groups their position can be transmitted independently to the camera. The hot-line operates independently of the main focussing command system, an the benefit is, apparently, that the body-side control unit can continuously grasp the position of the focusing lens, and thus can control auto-focusing at high speed. The hot line operates at between 8 and 20 MHz.

Just to add to this, there's a few patents, all saying more or less the same thing - US10831084, US10871623, US10895710, US11415771, and applications US20190129121A1, US20200026151A1, US20200068114A1, US20210011254A1, US20210072622A1, and US20230168461A1. It's clear that these are the Z mount (previously identified 'Z' patents have actually been Nikon 1 mount patents) by the diagrams, such as this:

showing clearly the four-claw Z bayonet. Having put my brain into gear (it takes longer to get started these days), I can say a bit more about what these pins are:
1. LDET. This is the last pin that will be engaged as the lens is twisted on anti-clockwise. It performs a 'lens detection' function. It's pulled high by the camera, the lens pulls it to ground. All the other pins (including power supplies) are disconnected until LDET is asserted.
2. VBAT. Raw battery power supply for lens motors, maximum 10V.
3. PGND. Power ground.
4. V33. 3.3V logic power supply to lens.
5. GND. Logic ground to lens.
6. RDY. Lens pulls low to signal ready to communicate.
7. DATAB. SPI data from body to lens (MOSI). Communications always start with body-issued command. Data rate is 8MHz.
8. CLK. SPI clock from body to lens.
9. DATAL. SPI data from lens to body (MISO). This follows SPI classic loop around, with lens returning data following first command from body. RDY is de-asserted by lens after each byte whilst lens processes and actions last byte.
10. HCLK. SPI clock from lens to body for 'Hot-line' communications. Data rate is 8-20 MHz
11. HDATA. SPI data from lens to body for 'Hot-line' communications.
I worked out what the 'hot-line' link is all about. It's for using adapted F-mount lenses. The F-mount is hard to adapt to mirrorless because it doesn't have absolute focus positioning. It developed from the original screw-drive mount, and in the AF-S (an other in-lens motor versions) the command set was supplemented with motor on and direction commands, which the camera used just like it would turning on its own motor for screwdrive lenses. In other words, all they did was move the motor to the lens. For the higher end cameras a couple of extra pins were added for 'hot-line' signals (that is what Nikon called them) which fed back from the lens a pair or quadrature signals encoding focus scroll movement and direction. This allowed the camera to track the focus movement and control the focus motor more precisely. The 'hot-line' interface in the Z mount does the same thing, but translated to digital codes. I doubt whether it's used at all for native Z lenses, although the patent also talks about to sending aperture and 'blur correction' information, which I guess could be useful for video.
As for 'blur correction', of course what it's talking about is lens IS (VR) - by feeding back the configuration of the lens stabilisation elements it can enable combined AF with the IBIS.

Exactly so.

Works for me, but maybe because it's cached somewhere in Google.

Try patents.google.com/patent/US10831084B2