Running equation of time mechanism controlled by a differential device
AssigneeMontres Breguet S.A.
InventorsSylvain Dauby, Alain Zaugg
Life of this patent
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Abstract
A running equation of time mechanism includes civil hour and minute hands to indicate civil time and a concentric true minute hand to indicate true time. The running equation of time mechanism includes an equation of time cam and a differential gear device, a first input of which is formed by a civil minute pipe on which a civil minute hand is pressed, and a second input of which is formed by the equation of time cam. The differential gear device includes a planetary reducer wheel set via which the civil minute pipe drives a civil hour pipe on which is pressed the civil hour hand, and a planetary multiplier wheel set via which the civil hour pipe drives a true minute pipe on which is pressed the true minute hand.
Claims18
A running equation of time mechanism comprising:
- a hand arrangement whose purpose is to indicate civil time by a civil hour hand and a civil minute hand, and a true minute hand,
- an equation of time cam having a profile which is determined by a difference, on every day of the year, between civil time and true time, wherein said equation of time cam is driven in rotation at a rate of one revolution per year by a timepiece movement, wherein the position of the true minute hand is determined by the position of the equation of time cam, and
- a differential gear device whose first input is formed by a cannon-pinion integral with a civil minute pipe on which is pressed the civil minute hand, and whose second input is formed by the equation of time cam, wherein the differential gear device includes a planetary reducer wheel set, via which the civil minute pipe drives a civil hour pipe on which is pressed the civil hour hand, and a planetary multiplier wheel set via which the civil hour pipe drives a true minute pipe on which is pressed the true minute hand.
Dependencies are inferred from the claim text.