You probably don't think too often that you need slightly different moon phase mechanisms for a watch in the northern hemisphere compared to the southern. In fact, all you need is for the moon phase wheel, the wheel that has the moon on it, to rotate in the opposite direction: right to left on most watches.
In most watches, this would just be a matter of adding a gear, or assembling the mechanism differently. But what, Breguet asks, what do you do for someone who travels from the northern hemisphere to the southern, or vice versa?
Well, for that world traveler, who only wants to bring one watch with them, Breguet has an answer: a moon phase mechanism with counterrotating wheels, two heart cams, and a selection mechanism to engage one or the other.
This is an interesting patent in that it may do fewer new things than any other modern patent we've featured here. It's basically two moon phases, with a selector between them. The heart cams allow the selection lever to engage one wheel or the other.
Like many of the patents here, this one is unlikely to see manufacture. It's not a really meaningful improvement on the existing mechanisms, and has incredibly limited real world use.
Here's the thing with moon phase complications: they're popular, they're mechanically simple, and they're very bad at accurately displaying anything other than full and crescent moons.
The way most work is to have a semicircular opening with a smaller semicircle, or occulation disk on either end of the semicircle. As the moon emerges over left side, it starts as a tight crescent, and slowly grows to a full moon, before waxing. But the middle areas between the full moon and crescents are poor representations of the moon. If you check your moon phase at a half moon, it will look like a moon cookie with a bite taken out of it more than a half moon.
Enter Audemars. Their stated goal with this patent was to create a complication that did not add substantially to the complexity of the movement, while providing a more accurate representation of the moon at any given phase. What they've come up with is a really clever mechanism that was patented in the United States on July 30, 2013.
They maintain a few staples of more common moon phase complications. As shown in the patent, it keeps the semicircular opening for the complication, a moon disk with two moons opposed at 180 degrees from one another, and the traditional rotation rate of 29.5 days per half-turn. That is where the similarities end.
Instead of having semicircular occulation disks, the patented complication has two rotatable occulation disks that look vaguely like those three winged boomerangs. The disks can be calibrated to provide more accurate occulation of the moon at particular parts of its orbit. As the moon disk rotates it engages gears that move the occulation disks, typically in one quick movement, like with a date change.
In the end, this is a very interesting, but very high end complication. It adds a lot of pieces to what is typically a simple and inexpensive addition to a watch. I would really love to see this make its way into a watch, either by AP or licensed by someone else.