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SUMMARY:MEchanics GAthering -MEGA- Seminar: Flexure Pivot Oscillators for 
 Mechanical Watches
DTSTART:20200326T161500
DTEND:20200326T173000
DTSTAMP:20260415T000624Z
UID:56ba779c80fceb9fb65aae67a7342193e872cf4aeaa8939e9b9f4834
CATEGORIES:Conferences - Seminars
DESCRIPTION:Etienne Thalmann\, Instant Lab\, EPFL\nIt appears that the con
 certed efforts of the watchmaking industry are leading towards a limit in 
 the accuracy of mechanical watches. The general consensus in horology is t
 hat the quality factor of the time base\, a dimensionless number that char
 acterizes the damping of an oscillator\, needs to be improved for the accu
 racy of the timekeeper to increase. The three classical mechanical time ba
 ses all suffer from limitations in the context of a mechanical watch appli
 cation. The solution appears to be flexure pivot oscillators in silicon. T
 he use of flexures instead of bearings eliminates contact friction and the
  choice of monocrystalline silicon minimizes internal friction\, leading t
 o significant improvements in quality factor in comparison to balance spri
 ng oscillators. \nAccurate timekeeping requires the period of oscillation
  of the time base to stays as regular as possible regardless of changes in
  operating conditions such as amplitude of oscillation and orientation wit
 h respect to gravity. We focus on minimizing the effects of amplitude and 
 gravity that arise from the use of flexures. The first technical contribut
 ion is to note that the isochronism defect is a second order phenomenon\, 
 and to deal with it by modifying the second order behavior of flexure spri
 ng stiffness and inertia. The second technical contribution is a design me
 thod to make the effect of gravity constant for all orientations of the ti
 me base by ingeniously placing the flexures and exploiting the position of
  the center of mass. These findings are embodied in two new flexure pivot 
 architectures called Gravity Insensitive Flexure Pivot (GIFP)\, co-RCC fle
 xure pivot oscillator (co-RCC) and Rotation-Dilation Coupled Oscillator (R
 DCO). A silicon prototype satisfying typical mechanical watch specificatio
 ns is manufactured. The technical contributions of the thesis are validate
 d by finite element simulations and experimental measurements on the proto
 type.
LOCATION:MED 2 2423 https://plan.epfl.ch/?room==MED%202%202423
STATUS:CANCELLED
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