Timepiece able to indicate the sunrise or sunset anywhere in the world

摘要

The timepiece comprises means for indicating the sunrise and sunset taking account of seasonal variations. These means comprise a sphere reproducing the terrestrial globe, a shell arranged concentrically to the sphere and arranged to demarcate one portion of the terrestrial globe where it is night from another portion where it is day by indicating the position of the Earth's terminator. The shell can pivot about the globe on two axes perpendicular to each other. The shell is driven by the movement so as to rotate at a rate of one revolution per 24 hours about the polar axis. A disconnecting mechanism is controlled by an annual cam which has a profile representative of the tilt of the Sun with respect to the equatorial plane. The disconnecting mechanism controls the tilt of the shell about the axis by means of a drive shaft concentric to the polar axis.

主权项

1. A timepiece comprising a timepiece movement and means for indicating the sunrise and sunset taking account of seasonal variations, said means comprising a sphere reproducing the terrestrial globe, a support, and a circle mounted on the support and arranged concentrically to the sphere, the circle being arranged to indicate the position of the Earth's terminator, the circle and the sphere being arranged to be able to pivot with respect to each other along two perpendicular axes, a first of the two axes, referred to as the polar axis, corresponding to the polar axis of the terrestrial globe, and the second axis, referred to as the ecliptic axis, intersecting the polar axis at the centre of the sphere, the circle being free to rotate with respect to the support about the ecliptic axis, the sunrise and sunset indicator means further comprising an annual cam having a profile representative of the tilt of the Sun with respect to the equatorial plane and arranged to be driven in rotation by the movement at the rate of one revolution per year, a cam follower arranged to cooperate with the cam, and a kinematic connection arranged to connect the cam follower to the circle such that the plane subtended by the circle forms, with the polar axis, an angle equal to the tilt angle of the Sun with respect to the equatorial plane, wherein:
the support is arranged to be driven by the movement so as to rotate at a rate of one revolution per 24 hours about the polar axis while driving the circle; the sunrise and sunset indicator means comprise a drive shaft concentric to the polar axis and arranged to be driven in rotation at the same speed as the support, but angularly offset with respect to the support; the kinematic connection between the cam follower and the circle comprises a disconnecting mechanism connected to the cam follower and to the drive shaft, and arranged such that the angular offset is representative of the tilt of the Sun with respect to the equatorial plane, the kinematic connection further comprising transmission means arranged such that a change in angular offset results in a corresponding change in the value of the angle between the plane subtended by the circle and the polar axis; the kinematic connection between the cam follower and the circle is an intermittent connection, the disconnecting mechanism being arranged to periodically readjust the angular offset by forming a transient coupling between the drive shaft and the cam follower.