Did you know there is still a significant market for quartz analog wristwatches, even in the era of smartwatches? The research says in recent years they account for nearly three-quarters of the market for conventional wristwatches — which is estimated to value $66 billion dollars in the U.S. this year. That is larger than the global market for smartwatches. 

 

What’s even more interesting is that the analog quartz watches of today are basically unchanged from the first designs, introduced almost 60 years ago by a Swiss consortium and a Japanese watchmaker, Seiko. Both those watches and today’s modern version use something called a Lavet-type Motor. Invented by French engineer, Marius Lavet, the Lavet motor can only turn in one direction, which is dependent on the geometry of the stationary element (the stator) of a magnetic rotor.

 

However, the long-unchanged analog quartz wristwatch may finally get some technological updates in the form of silicon microelectromechanical systems (MEMS) that are half the size of the standard Lavet stepper motor currently used, which already uses miniaturized magnets to function. The future of such advancements remains to be seen.

How Does the Historical & Modern Lavet Work?

Used in a single-phase Lavet-type stepping motor, permanent magnets function as rotors. As mentioned, it can only turn in one direction, which is dependent on the geometry of its stator, the stationary element of the magnetic rotor. A circuit is then used to generate a bipolar pulse, meaning it delivers both positive and negative voltage to the coil in short intervals. When the electromagnet is turned on, it attracts the poles.

 

Another essential element of the Lavet motor is the cogging points (angles where the volume of air between the magnetic rotor poles and the bulk of the stator is reduced). These can differ depending on whether the stator coil is energized or not. Without a flowing current, the cogging points are caused by reluctant force against a magnetic field vs. slowing the propagation of an alternating magnetic flux.

 

Here is the movement process in the Lavet motor: 

 

  1. Currentless stator; rotor’s north pole points to the upper left.
  2. Energized status; rotor moves clockwise; the north pole points to the right.
  3. As energization declines, the rotor moves further until the north pole points down.
  4. Stator energized in the opposite direction; rotor moves clockwise; north pole points left.
  5. After energization declines, the rotor returns to its original position.

 

Ultimately, in order to make the Lavet motor rotate, the current sent through its stator coil needs to change direction at each step (i.e., bipolar), followed by an interval without current when the rotor moves to a reluctant position.

Apex Magnets

For companies that create analog or stepped-movement quartz clocks (including wristwatches), magnets are an important element of manufacturing, and they will continue to be whether the Lavet or silicone MEMS is used. As the world of technology and manufacturing evolves, you can count on us to keep you informed on the best ways to employ magnets. If you are looking to purchase magnets today, don’t forget to browse our product catalog.