The advent of the self-winding watch ushered in a new age of design in watches. It also increased the thickness of watches. In most designs, the rotor was concentric with the movement, and stacked below the gears. But there was a way to limit the increase in thickness, as Universal Perret Freres (later Universal Geneve) said eloquently in their 1956 patent application:
According to a primary feature of our invention, the rocking weight has its axis arranged eccentrically with that of the watch and it is arranged in superposition with the winding mechanism above the watch plate within the space left free on the latter by the mainspring, the movement and the balance wheel while the total height of said weight and winding mechanism is at least approximately equal to that of the movement.
This concept, of having the rotor co-planar with (at least part of) the movement, is what we now know as a micro-rotor. This patent (really, this one is worth a read) goes into some depth as the problems with alternative low-height winding mechanisms.
The micro-rotor is still something of a niche item, but it's very interesting to see a patent describing it as early as the mid 50s.
This Gruen Patent from 1972 is featured not because it's particularly groundbreaking, but because it does such a great job at showing one common way to implement day-date mechanisms.
The day indicator is linked to the seven-sided star gear shown in the center, and it's advanced by the wheel to its left with a single finger. That wheel rotates once a day, and once a day rotates the star gear by 1/7th of a rotation, advancing a day wheel that shows the day of the week on the face of the watch.
Meanwhile in this implementation, the finger in the lower left will connect with the spurs on the date wheel around the edge. As it completes its rotation, it will advance the date wheel just like the date wheel does.
This particular implementation has a couple of interesting tweaks. The date cam is in a groove, so as it rotates around it also extends out a bit to better engage the spur. It also keeps the two wheels (day star wheel, and date wheel) in place with springs, that aid in limiting the movement to once a day when engaged by their respective cams.
This is a delightfully over the top patent. Granted in December, 2017, this patent describes an adjustable mechanical snooze function on a watch with an alarm.
I say this is over the top because watches with alarms are rare enough. It seems unlikely that anyone would actually manufacture one with a snooze feature (prove me wrong if they exist already), let alone an adjustable snooze.
The mechanism by which the snooze is achieved is pretty straight froward. There's a rack and cam (pictured above). The angle of the rack determines the duration of the snooze, and the cam has multiple points where it can set the angle of the cam.
This is really one of those patents that would make an absurdly high-end watch. Would I use this if I had it on a watch? Of course I would. Would I ever buy one? I cannot imagine a world where I would.
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.
In late November, 2016, Rolex was granted a patent for a complication that would serve a similar purpose to a chronograph, but with fewer parts, thereby making it more reliable, smaller, and lighter than traditional mechanical chronograph movements.
The basic premise is to have a your normal hour, minute, and second hands (shown as a small seconds in the patent drawings), and then "stored" hours, minutes, and seconds hands. Both sets move in sync until you freeze the "stored" time hands. Then, instead of having a readout of how much time has elapsed as with a typical chronograph, you simply have a display of when you stopped the clock.
Two heart cams then serve to resynchronize the seconds with seconds, and hours and minutes with the actual time. Heart cams are routinely used to zero out chronographs, so they have a long history in watchmaking.
I feel that it's unlikely this makes it into a Rolex watch. (The discussion of why you patent something if you're never going to sell it is for another day.) It's not clear where it would fit in their line, and it seems like most people would correctly view it as a cheaper, less convenient version of a chronograph. It's easy to read elapsed time. It's harder to do watch-math -- It's 8:37 now and I stopped the watch at 7:18. . . It's an hour and nineteen minutes, but it took you longer to get there than looking at a chronograph.
One thing that's notable about this patent is that it relates to a new complication, rather than improvements in materials or reliability to existing components. It's a little out of the ordinary for Rolex.
We don't plan to cover much of Rolex's materials patent portfolio here. It's not because it's not interesting; it really is. It's just that ceramic chemistry and metallurgy aren't as easily understood by the typical watch nerd as a bunch of gears and some simple drawings. And, if I'm being honest, aren't as easily understood by me either. When we do cover them, it's more likely going to be a "what does this mean," rather than getting too far into the "how."
This recently issued Rolex patent is a decent example.
The abstract reads:
Watch component made of a persistent phosphorescent ceramic composite material which is a sintered dense body comprising two or more phases, a first phase consisting of at least one metal oxide and a second phase consisting of a metal oxide containing at least one activating element in a reduced oxidation state, the watch component having a surface which comprises an area which shows phosphorescent emission and an area which does not show phosphorescent emission or which shows phosphorescent emission with an intensity which is lower than that of the emission of the other area.
The patent covers a ceramic element of a watch that is either partially phosphorescent, or has elements that have different phosphorescent properties. Like hour indices that look like one piece in day light, but only the tips glow. Or a solid ceramic bezel where indices on the bezel are luminescent. It's potentially pretty cool.
These patents are dense. Like fruitcake dense. Flourless chocolate cake dense. While most mechanical watch patents are pretty brief, and explain the relevant gearing and positions in relation to other gears in the train, these patents go into great detail (see the image) above regarding how the ceramic was manufactured, and which temperatures and concentrations of metals provided what results. It's good technique for getting a broad patent, but it's not easy for me to post a picture of ceramic crystals and have the implications of that be apparent for watch fans.
All of which isn't to say we will never cover them, but my feeling is that these will be of less general interest to readers than a day-night complication where the moon also displays the moon phase.
From time to time we will revisit some much older patents. They show us some ideas that either never caught on, or did but have since been improved upon or gone out of style.
This Benrus patent was issued in 1952 and expired in 1969.
This patent disclosed a simpler way to adjust watch bracelets. The bracelet features a traditional tri-fold clasp, but also allows quick adjustment to make the bracelet tighter or looser. An internal spring bar and several notches allow the user to easily adjust the fit of the bracelet while it is still on their arm, all invisible to the user.
The patent suggests that on hot days you may want a little more room in the bracelet, or to quickly push it up your arm while washing your hands.
It's a clever idea, though I don't know that it was ever mass produced. And certainly the spring bar would loose resilience over time and the bracelet would begin to slip, which is a major downside.
Meanwhile, we have seen some quick fine adjust mechanisms on bracelet clasps lately, but none that I'm aware of that let you adjust the fit while it's on your arm.
Even Lange's patent drawings are things of beauty. This patent, which expired in September, 2016, discloses and claims a beautifully simple mechanism to zero a second hand while setting the time.
The basics of this mechanism is a cam-plate drive. The cam plate can be seen attached to the seconds stem. When the crown is pulled into the setting position the cam is driven by a spring-driven lever into the zero position. By using a heart-shaped cam, the mechanism will also hack - keep the second-hand at the zero position while the minute hand is being set.
For such a desirable feature, there are surprisingly few parts involved, and given that the patent on this mechanism has expired, I'd love to see to lower-end watch companies start to incorporate this into their watches.