A novel clock display?

[pythoncoder]

I'm rarely impressed by alternative clock displays firstly because the traditional analog design is so damn good. You can tell the time at a glance just from the angle between the two hands: how can you improve on that? But then I found this on the internet:
bizarre watch display
Hard to realise on a mechanical watch but interesting. And it got me thinking. Some years ago I implemented analog and digital clocks on an e-paper display. In theory e-paper should be ideal for clocks with exceptionally low power consumption: zero if you switch them off! Results were poor as there are two choices. Either you refresh the display normally, in which case every (say) 1 minute the screen goes through a five second rigmarole to update. Or you use fast updates, in which case you get ghosting. I wrote it up and abandoned it.

E-paper displays in fast mode are additive. Ghosting only occurs when you turn a black pixel white. I therefore devised this adaptation of the video which only turns pixels white with a full refresh once per hour.

As in the video the display inside the circle is a window onto a dial too large to fit the screen. The dial is the minutes display, with a range of +-30 minutes. The hour hand (chevron) moves to the next hour when the minutes pass 30, with the minutes before or after the hour shown by the black band on the scale.

The above image shows 20 to 7 PM, that below shows nearly quarter past 2 PM. Like a conventional analog clock it encourages reading the display in the way in which we normally describe time.

Implemented on a Pyboard 1.x with Pervasive Displays EPD.

I'll post code in my e-paper repo in due course. Any comments or thoughts on the format?

[jimmo]

That's very cool -- I've experimented with e-paper in the past for numerical displays and never quite got the effect I wanted.

I do really like this concept though -- both the video you linked to and your adaptation! Looking forward to testing it out on one of my displays.

[pythoncoder]

I should add that the once per minute updates are virtually imperceptible - the display as a whole is rock-solid. You have to stare at the dial to see the black bar extend fractionally. Once an hour, on the half hour, it necessarily goes through the update performance.

[pythoncoder]

Code may be found here. I wrote the graphics routines with a view to easy porting to other displays, but optimising text positioning was a manual process.

Inevitably any fast mode of an e-paper display is hardware dependent.

[torwag]

Hi,
Late to the party. That is very neat. Just wanted to say that there was pepple with the pepple watches using an colour eink display. You could program your own watchfaces and some looked similar like what you showed.
pepple watches were great and advanced their time by many features unseen even now.
pepple Inc was sold to fitbit and they instantly terminated the watch and all infrastructure to use the watch.
One more sad example of a technology which was supere but could not stand against the giants in tech industry.

However rumours say that the pepple watch should be able to run micropython maybe the second hand market is full of nicely designed eink displays to be run by micropython.

[pythoncoder]

I've just looked at the pebble article on Wikipedia. A 64 colour ePaper display is quite something - except that it might have been vapourware. I guess we'll never know.

I do wonder how professional users of ePaper handle ghosting. I spent a lot of time on this, without achieving satisfactory results. I found internet videos showing ghost-free additive refreshes, but oddly none were accompanied by code, algorithms or web references. I began to smell a rat.

The only decent clock display I made was this additive design which works round the problem rather than fixing it.

[T-Wilko]

Very cool watch face, almost looks naval and it seems a good way of countering ghosting.

Might be worth mentioning that Garmin watches being made now (such as the Garmin Instinct, Fenix, Forerunner series) have a variant of Pebble's trans-reflective LCD in them with fairly similar tech behind it. I assume it's a slightly different product as they call it a 'Memory-in-pixel' (MIP). From what I've read here it seems that it does work *sort of* like ePaper. Judging by my new Instinct watch and the general design philosophy, it doesn't seem to possess any 'fast mode'-esque style of pixel refresh.

Next step: flashing micropython on to my new garmin