Timepiece having a time indicator hand which is movable between two positions

Timepiece having a timepiece movement and comprising a time indicator hand which can indicate a first piece of time information when in a first position, and a second piece of time information when in a second position; a first time indication moving part; and a second time indication moving part, in which the timepiece movement includes a first cam (7) which is fixed to the first time indication moving part (9) and which is shaped to shift the time indicator hand to its first position, and a second cam (8) which is fixed to the time indicator hand and which is shaped to shift the time indicator hand to the second position.

BACKGROUND ART

The present invention relates to a timepiece including a time indicator hand which is movable between two positions to indicate two different pieces of time information.

Timepieces of this type are known in the prior art.

More specifically, EP 1 959 317 describes a timepiece which has a switch mechanism enabling the time indicator hand, for example the minute hand, to indicate two different pieces of information, such as the current time and the stop watch time, according to its movement, caused by the actuation of a push button, between a position for indicating the current time and a position indicating the stop watch time.

The switch mechanism which is described includes a transmission pinion rotated by a first moving part of the timepiece movement so as to represent a first piece of information to be displayed, and an element having a first split-second core mounted idly on the transmission pinion and rotated by the first moving part or by a second moving part of the movement so as to represent a second piece of information to be displayed.

The switch mechanism also includes a second split-second core fastened to the transmission pinion, a transmission wheel mounted idly on the transmission pinion and having a first and a second hammer biased against the first and second core respectively, a switch wheel mounted rotatably on the periphery of the transmission wheel and having a first and a second cam acting, respectively, on the first and the second hammer so as to separate, alternately, the contact between the first hammer and the first core and the contact between the second hammer and the second core respectively, in order to change the position of the transmission wheel according to the first or second piece of information to be displayed, respectively, an intermediate drive wheel being mounted idly on the transmission pinion and engaging with the switch wheel, the intermediate drive wheel being fastened to a drive wheel which can be rotated in a controlled way by means of a driving mechanism of the transmission mechanism.

The switch mechanism described in EP 1 959 317 is complex because of the use of numerous parts and their arrangement. In particular, it requires a transmission wheel with two hammers and a switch wheel with two cams.

Another switch mechanism for a timepiece enabling the minutes or the date to be indicated by the minute hand is described in CH 693 155.

This mechanism operates with a differential system and a planet gear fixed to a resetting cam, the differential system enabling an angular movement to be imparted to the minute hand to indicate a date. This mechanism is complex, and the planet carrier placed between the moving parts of the differential occupies a certain amount of vertical space.

Consequently there is a need to replace the existing switch mechanisms, and to simplify the timepiece movements, in timepieces in which a single time indicator hand can indicate two different pieces of information.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the aforementioned drawbacks, at least partially.

For this purpose, the present invention describes a timepiece having a timepiece movement and comprising a time indicator hand which can indicate a first piece of time information when in a first position, and a second piece of time information when in a second position; two concentric fixed scales for displaying the first and the second time indication respectively; and a first time indication moving part and a second time indication moving part, positioned concentrically and connected to the timepiece movement so as to be driven with two different periodicities.

The timepiece movement is distinctive in that it includes a first cam which is fixed to the first time indication moving part and which is shaped to shift the time indicator hand to its first position, a second cam which is coaxial with the first cam, is fixed to the time indicator hand and is rotatable with respect to the first cam, and which is shaped to shift the time indicator hand to the second position, a lever mounted pivotably on the second time indication moving part, actuating means for making the lever engage with the second cam in order to shift the time indication hand to the second position, and resilient return means engaged with the first cam to return the time indicator hand to the first position as soon as the lever ceases to engage with the second cam.

Advantageously, the resilient return means include a rotatable moving part to which the second cam is fastened and which can be rotated with respect to the first cam.

Also advantageously, the resilient return means include a pressure roller which moves on the first cam, and resilient means for returning the pressure roller into the recess of the first cam to position the time indicator hand in the first position, all these means being fastened to a face of the rotatable moving part opposite that to which the second cam is fastened.

Preferably, the rotatable moving part is fixed to a second tube to which the time indicator hand is fastened, and the first cam is fixed to a first tube which is fitted inside the second tube.

The lever has a first end which is substantially rounded and is intended to bear on the second cam, and a second end in the shape of a finger.

The means for actuating the lever include a transmission ring pivoting around the second time indication moving part and having, on its inner perimeter, teeth arranged so as to enable the lever to pivot with respect to the second time indication moving part by interaction between the second end of the lever and a tooth.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

The timepiece described below is, as shown inFIGS. 1 to 3, a wristwatch1indicating the time by means of an hour hand2and indicating the minutes by means of a minute hand3, the hands being placed in a first position which is read with respect to a first fixed time indicator scale4.

Because of the distinctive mechanism of the timepiece movement according to the invention described with the aid ofFIGS. 4 to 10, one of the hands, which in the case of the illustrated embodiment is the minute hand3, is moved to a second position which is read with respect to a second fixed time indicator scale5, which in this case is a scale showing the date, after pressure on a push button6placed at the four o'clock position on the wristwatch1.

The timepiece movement according to the invention includes a first cam7, shown inFIGS. 4 to 7, shaped to shift the minute hand3to a first position, and a second cam8, shown inFIGS. 4 to 9, which is fixed to the minute hand3, coaxial with the first cam7, rotatable with respect to the first cam7, and shaped to shift the minute hand3to the second position.

A first time indication moving part9, shown inFIGS. 4,5and10, is fixed to the first cam7and is, in the illustrated embodiment, the cannon pinion linked to the motion work.

The cannon pinion9and the first cam7are fixed to a single tube10called the “first tube”.

A second time indication moving part11, shown inFIGS. 8 to 10, located coaxially and rotatably around the first time indication moving part9, is freely rotatable with respect to the second cam8. It is connected to the timepiece movement in such a way that it is driven with a periodicity different from that of the first time indication moving part9. In the embodiment described here, the second time indication moving part11is a date wheel.

A rotatable moving part12shown inFIGS. 4 to 7can be used to connect and disconnect the first cam7and the second cam8. It takes the form of a flywheel having a central part13to which the second cam8is fastened and a peripheral part14, such as a ring, connected to the central part13by three arms15.

The rotatable moving part12is fixed to a tube16called the “second tube” to which the minute hand3is fastened and inside which the first tube10is fitted. Resilient return means are fastened to the rotatable moving part12, on a face opposite the face to which the second cam8is fastened, and engage with the first cam7. They include a pressure roller17, connected to the ring14of the moving part12by a pivoting arm18. The pressure roller17moves against the first cam7.

A return spring19located on the ring14acts on the pivoting arm18and enables the pressure roller17to be returned to an equilibrium position corresponding to the positioning of the pressure roller17in the recess7aof the first cam7, as shown inFIG. 6. Thus the rotatable moving part12is mounted so as to be rotatable with respect to the first cam7.

As shown inFIGS. 6 to 10, a drive lever20of the second cam8is mounted pivotably on the date wheel11so as to engage with the second cam8in order to shift the minute hand3to the second position. Since it is positioned on the date wheel11, it moves together with the latter with respect to the second cam8.

It has a first substantially rounded end21intended to bear on the second cam8in order to move it to the second position, and a second end22in the shape of a finger.

As shown inFIGS. 8 and 9, the lever20is rotated by the interaction of its second finger-shaped end22with actuating means.

The means for actuating the lever20include a toothed transmission wheel23and a transmission ring24positioned coaxially and rotatably around the date wheel11, the toothed transmission wheel23carrying the transmission ring24.

The inner perimeter of the transmission ring24has teeth25which interact with the second end22of the lever20, thus enabling the lever20to pivot with respect to the date wheel11.

A return spring26acts on a pin27located on an intermediate part of the lever20in order to keep the lever fixed with respect to the date wheel11when the lever20is not moved by a tooth25.

The actuating means also include an L-shaped rocker29connected mechanically to a drive wheel30by the pressure of the end of the rocker29on a pin31of the drive wheel. The drive wheel30engages with the toothed transmission wheel23.

A projection32, coaxial with and fixed to a toothed wheel33engaging with the toothed transmission wheel23, pivots and bears with a curved surface on a jumper spring34to hold it between two teeth of the date wheel11in order to prevent any unintended movement of the latter in the course of the request for the date.

A return spring35enables the transmission ring24, the toothed transmission wheel23and the toothed drive wheel30to return, after the release of the push button6, to the respective positions which they assumed before the push button6was pressed.

As shown inFIGS. 8,9and10, the date wheel11has31uniformly distributed teeth, giving it the shape of a star. It is freely rotatable with respect to the second cam8, while it is connected mechanically to the pinion9and thus to the first cam7.

As shown inFIG. 10, the date wheel11is connected to the pinion9by a set of moving parts comprising a return pinion36engaging with the pinion9and with a first intermediate toothed wheel37having at its centre a pinion38engaging with a second toothed wheel39completing one revolution per day.

The second toothed wheel39engages with the hour wheel40and has in its centre a drive finger41of the date wheel11. The drive finger41causes the date wheel11to rotate with respect to the dial, together with the lever20fastened to the date wheel11, through one interval per day, thus enabling a new date to be indicated every day.

The operation of the timepiece mechanism described above is as follows.

When the user presses the push button6to discover the date, the movement of the push button6drives the rocker29which drives, by means of the pin31, the drive wheel30, the transmission wheel23and the transmission ring24whose teeth25drive the lever20. The drive lever20then pivots in the direction of the hands of the watch1, as a result of the movement of its second end22which is driven by the tooth25, as shown inFIGS. 7 and 9, and its first end21comes into contact with the second cam8which is fixed to the minute hand3.

The second cam8is then driven by the pivoting of the lever20. The rotatable moving part12fixed to the second cam8and to the second tube16pivots around the first tube10. The movement of the rotatable moving part12stops as soon as the lever20is in the recess8aof the second cam8, and in this case the minute hand3is located in the second position, corresponding to the second time indication.

When the user releases the push button6, the rotatable moving part12and the second cam8are returned under the action of the resilient means and the pressure roller17, thus causing the rotation of the second tube16and of the second cam8around the first tube10, until the pressure roller17is located in the recess7aof the first cam7corresponding to the first position of the minute hand3.

The lever20is then driven in the opposite direction to the hands of the watch1, by means of its first rounded end21which is in contact with the second cam8. The pin27of the lever20locks into the fork of the return spring26.

The transmission wheel23and the transmission ring24are driven in the opposite direction to the hands of the watch1by the return spring35, causing the movement of the drive wheel30and consequently the movement of the rocker29by means of the pin31.

In this case, the second cam8and the rotatable moving part12are driven together with the first cam7, and consequently with the pinion9, by means of the pressure roller17. The minute hand3, fixed to the second cam8by the second tube16, follows the movement of the pinion9and indicates the first position. In other words, the first tube10and the second tube16pivot together.

Thus the resilient return means, particularly the rotatable moving part12and the pressure roller17, are connected to the first cam7when the push button6is released and are disconnected from the first cam7when the push button6is pressed and the lever20is in contact with the second cam8.

Other arrangements of the rotatable moving part12, the two cams7and8, the first tube10and the second tube16are possible, the essential feature being that the second cam8can pivot with the first cam7without the action of the lever20and can pivot independently of the first cam7under the action of the lever20, this lever being mounted on the date wheel11and being moved once every day at a given frequency with respect to the dial of the timepiece.

The present invention can be applied to any time indication, for example a power reserve indicator, as an alternative to the date indication, and can be applied to any time indicator hand, for example the hour hand2, as an alternative to the minute hand3.

In a variant, it would be possible to connect the date wheel11to a perpetual date mechanism.