WO2006029721A1

WO2006029721A1 - Timepiece displaying the day of the month comprising a device for a running time equation

Info

Publication number: WO2006029721A1
Application number: PCT/EP2005/009424
Authority: WO
Inventors: Marco Rochat
Original assignee: Frederic Piguet S.A.
Priority date: 2004-09-15
Filing date: 2005-09-01
Publication date: 2006-03-23
Also published as: EP1792235B1; EP1637941A1; EP1792235A1

Abstract

The inventive timepiece comprises a watch movement, a calendar date mechanism (124) and a pair of hour and minute hands (10, 12) displaying a civil time and an additional minute hand (16) which displays a true minute and is driven by a true time display mechanism, wherein the day position of the true time minute hand (16) is determined by the position of a time equation cam (64) rotationally driven at one revolution per year by the calendar data mechanism (124). Said timepiece is characterised in that the true time display mechanism actuates a mobile carrying an additional hour hand (14) displaying the true hour.

Description

QUANTIME WATCH PIECE COMPRISING A DEVICE OF EQUATION OF THE WALKING TIME

The present invention relates to a timepiece comprising a time equation mechanism with display. More particularly, the invention is directed to a walking time equation mechanism operating a true time minute hand that indicates the gap between true solar time and civil time. As we know, there is a gap between the true solar time which corresponds to the duration that elapses between two consecutive upper passes of the Sun to the meridian of the same place, and the average solar time or civil time which is the average , made on the year, the duration of all solar days true. This difference between the civil time and the true time reaches +14 min 22 s on February 11, and -16 min 23 s on November 4 as shown in Figure 1 attached to this patent application. These values vary little from year to year.

To indicate the difference between the civil time and the true time, certain timepieces include a mechanism said to equation of walking time, that is to say whose switch has two minute hands, one indicating the civil time and the other the true time, the minute hand of the true time being actuated by a weather equation cam whose profile is determined by the difference between the mean solar time and the true time at a given instant .

The cam is rotated at the rate of one revolution per year by a simple or perpetual calendar mechanism. The simple date is a mechanism that can indicate the day of the week, the day of the month, the month of the year or the phases of the moon, but which does not take into account the variation of the number of days in the months (months of 28, 29 or 30 days). In other words, the user of a watch comprising a simple date mechanism will have to make a manual correction every month ends that are less than 31 days. For example, February 28 or April 30 will require manual correction. With regard to the perpetual calendar, it allows, as a simple date mechanism, to indicate the day, the date, the month and the moon phases. But, unlike the simple calendar mechanism, the perpetual calendar mechanism automatically takes into account the length of the months (28, 29 or 30 days), and this without manual intervention. A perpetual calendar mechanism therefore automatically takes into account leap years.

An example of a timepiece comprising a walking time equation mechanism of the kind described above is given by the European patent application EP 1 286 233 in the name of the Applicant. A disadvantage of this mechanism is that it only takes into account the difference between the minute of the civil time and the minute of the true time. However, this indication is incorrect since it would also be necessary to take into account the difference between the civil time of the place where one is and the civil time of the reference time zone to which one belongs, deviation that can be affected by the transition from winter time to daylight saving time and vice versa. In the case of a country like Switzerland which is in the time zone of Greenwich, the position of the zone is such that the civil time in Switzerland is one hour ahead of that of Greenwich in winter. During the daylight saving time, the Swiss calendar time is incremented by one additional hour, so that it is two hours ahead of the Greenwich civil time. On January 9 (winter time), the sun is 6.57 min behind the civil time. Thus, when the sun is at its zenith, the Greenwich civil time is 12h 07min. In Switzerland on the other hand, the watch will indicate 1 hour more, that is 13h 07min. On July 9 (summer time), the sun is 5.06 min behind schedule. Thus, when the sun is at its zenith, the civil time of Greenwich is 12h 05min. In Switzerland, on the other hand, the watch will show two more hours, ie 14h 05min.

The object of the present invention is to overcome the aforementioned drawbacks as well as others by providing a date timepiece comprising a walking time equation device which makes it possible to indicate the exact civil time of the timepiece. where you are when the sun goes to its zenith.

For this purpose, the present invention relates to a timepiece comprising a watch movement and a date mechanism, this timepiece having a pair of hour and minute hands which indicate the calendar time, and an extra minute hand which indicates the minute of the true time and which is driven by a true time display gear, the daily position of the minute hand of the true time being determined by the position of an equation cam rotational time rotated at a rate of one revolution per year from the date mechanism, characterized in that the display wheel of the true time drives a mobile carrying an extra hour hand which indicates the true time.

Thanks to these features, the present invention provides a timepiece whose walking time equation mechanism provides a complete indication (hour and minute) on the true solar time. Thus, when the solar time coincides with the civil time (this happens four times a year), the true time switch provides the same indication as the civil time switch at the center of a time zone like the Greenwich meridian . On the other hand, when the solar time is in ahead or behind the civil time, the true time hour hand provides the same indication as the civil time hour hand, while the true time minute hand is delayed or shows an advance of a few minutes on the minute hand of the civil time. This is true, however, only in the center of the time zone on which the equation of walking time is based. Indeed, in the same time zone, there may be a difference between the civil time of the place where one is and the civil time in the center of said time zone, which difference may be induced by the passage of time winter in summer time and vice versa. This is why there is a real interest in being able to shift the calendar time indicated by the watch according to the calendar time of the reference time zone.

For this purpose, and according to a complementary feature of the invention, the timepiece comprises a correction device that shifts the calendar time indicated by said timepiece according to the calendar time of a time zone reference without changing the indication of true time. Thus, on January 9, while the sun is delayed by 6.57 min on civil time, the watch according to the invention which has been previously set by its user to provide an indication of the civil time in Switzerland will display 13h 07min when the sun will be at its zenith. Likewise, on July 9, when the sun is 5.06 min behind the civilian time, the watch will show 14:05 min, while the true time switch will show 12:00. Therefore, whatever the the time zone in which the wearer of the watch is located, he will know at all times the exact difference between the civil time and the solar time.

Other features and advantages of the present invention will emerge more clearly from the detailed description which follows of an embodiment of the timepiece according to the invention, this example being given for purely illustrative and not limiting purposes only, in connection with the appended drawing in which:

- Figure 1, already mentioned, is a representation of the graph of the equation of time for the year 2003 on which are indicated the dates 1, 11 and 21 for each month, the months of the year being indicated in figures romans and the difference between the civil time and the solar time being indicated in minutes;

- Figure 2 is a plan view of the dial of a timepiece according to the invention according to a first embodiment;

- Figure 3 is a plan view of the dial according to a second embodiment; - Figure 4A is a schematic representation of time zones;

- Figure 4B is a schematic representation of longitudes; FIG. 5A is a sectional view of the left part of the civil time timer mobile and the true time timer mobile:

FIG. 5B is a sectional view of the right part of the civil time timer and the true time timer mobile; FIG. 6 is a plan view of a wheel whose position is indexed by a star twelve teeth and a jumping spring;

FIG. 7 is a plan view of a time equation cam;

FIGS. 8A and 8B are plan views of the mechanism for defining the longitude; FIG. 9 is a plan view of the mechanism for managing the longitude, and

- Figure 10 is a sectional view of the date mechanism.

The present invention proceeds from the general inventive idea of providing a timepiece which provides, in addition to an indication of the minute of true time, an indication of the time of the true time. Thus, in the center of a given time zone, there will be an exact indication of the solar time according to the civil time of the time zone. Sometimes, however, in a time zone, the civil time of the place where one is differs from the reference time of said time zone, this difference being able to be induced by the passage of the winter time to summer time and vice versa. To remedy this problem, it is proposed to increment or decrement the indication of the civil time in steps of one hour without changing the display of the true time. This gives an indication of the passage of the sun to its zenith corresponding to the civil time of the place where one is.

The present invention will be described in connection with a timepiece of the wristwatch type comprising a walking time equation mechanism actuated by an equation cam, itself driven in rotation at the rate of one revolution per year to from a date mechanism that can be indifferently simple or perpetual. In the case of a single date, the hour and minute hands of the real time can be reset by the user himself at the end of the months of the year with less than 31 days since the determination of the difference between the two hands of the minutes of the civil time and the true time is defined by the equation cam of the time driven by the date mechanism. Thus, during a date reset, the time equation cam is automatically placed in its exact position for the given day.

In what follows, we will not describe the watch movement in its entirety, but only the mobile timers of civil time and true time.

The timepiece according to the invention comprises in particular a dial whose plan view is shown in FIG. 2. Designated as a whole by the general numerical reference 1, the dial provides the wearer with different information. He first indicates, in a first small dial 2, the month of the year. We see in Figure 2 that the indication of the month of the year is by a needle 4. Of course, the needle 4 could be replaced by a record that would bear the inscription of the months of the year and which would turn under the dial 1 leaving the name of the month by an opening in said dial 1 and called wicket. A second hand 6 moving over another small dial 8 indicates the date (1 to 31) or date.

As can also be seen in FIG. 2, the timepiece comprises, in addition to a conventional switch whose function is to indicate the civil time and which comprises a 10-hour hand and a minute hand 12, a second hand. referral, concentric to the civil time switch, and which includes a second hour hand 14 and a second minute hand 16 which indicate the true time. To allow the wearer of the watch to easily differentiate between the hours of hours 10 and 12 minutes of the civil time and the hours of hours 14 and 16 minutes of the true time, the latter can end, for example, by a representation of the astrological symbol of the sun 18. The exact position of the hands 14, 16 of the true time for a given day is determined every day (once every 24 hours) around midnight, then the needles 10, 12 of the civil time and needles 14, 16 of true time move together, the gap between the hours of needles 10 and 14 and minutes 12, 16 remaining constant for the given day.

In addition to the date-related indications, the watch according to the present invention also provides an indication of the difference between the civil time of the place where one is and the civil time in the center of the time zone to which one belongs by means of a needle 20 moving in relation to a time scale 22. This time scale 22 is graduated hourly and extends between -4 and +4 hours, which corresponds to the maximum time difference that can be note between the civil time of a given place on the earth and the civil time in the center of the reference time zone to which this place belongs. The user thus instantly knows the value of the offset applied to the calendar time displayed by the watch relative to the civil time in the center of the spindle.

Our globe is divided into 24 time zones of 60 minutes each, each time zone corresponding to 15 ^degrees of longitude (see Figure 4A). The Greenwich meridian, passing through London, is located in the middle of a time zone and carries longitude 000. Longitudes are counted from the Greenwich meridian from 0 to 180 ° eastward (E). example, the longitude of Bienne (Switzerland) is 007E15 (7 degrees and 15 minutes east longitude) and that of Athens is 023E44 (23 degrees and 44 minutes east longitude), and from 0 to 180 degrees west (W) (for example, the longitude of Lisbon is 009W08 and that of Rio de Janeiro is 043W14) (see Figure 4B).

Relative to its center, a time zone thus extends between -7.5 ° and + 7.5 ° longitude. Although the equation graph is the same for the whole planet, the sun does not go to the zenith at the same time, depending on where you are. Thus, for example, the sun will be at the zenith earlier in Paris than in London, although these two cities belong to the same time zone. To manage this difference due to the position in longitude of the wearer relative to the center of the time zone in which it is located, the watch includes a dial 24 graduated between -7.5 ° and + 7.5 ° above which moves a needle 26 adapted to rotate in both directions. Thanks to this mechanism of longitude management which will be described in detail below, the user can apply an offset of +/- 7.5 ° of longitude, a time shift of +/- 30 min at the time. true. However, before applying this offset, the user must specify whether he is standing in longitude West (W) or East (E). For this, it has an additional dial 28 above which moves a needle 30 which points either west (W) or east (E). The transition from the west longitudes system (W) to the longitudes system is (E) can only be done when the longitude management mechanism is at zero, in other words when the pointer 26 points to the zero of the dial 24. It must be understood that a displacement in the direction of longitudes is (E) corresponds to a reverse displacement in the direction of longitudes west (W). For example, someone who moves +6Ε from Greenwich will see the sun at the zenith at 11:36, while someone who moves +6 ⁰ W always from Greenwich will see the sun at the zenith at 12 o'clock 24min. The dial illustrated in FIG. 3 differs from that shown in FIG. 2 in that the display of the true time is eccentric. The hours 14 and 16 minutes of the true time move over a dial 32 which may have a shape corresponding to the astrological representation of the sun to allow the user to immediately make the difference between the display of the civil time and the display of the true time.

We are now interested in the watch movement according to the invention and, more particularly, in the civil time and true time timer mobiles in connection with FIGS. 5A and 5B appended to the present patent application. The movement of the watch (not shown) drives a wheel 34 mounted on a roadway 36 at the free end of which is fixed the minute hand 12 of the civil time. The roadway transmits the basic time information to an hour wheel 38 and then to a civil hour wheel 40 via a timer mobile 42 24

- 7 -

comprising a wheel 44 and a pinion 46 which achieve a reduction of 1/12. The calendar hour wheel 40 is fixed on a barrel 48 which carries, at its free end, the hour hand of the civil time.

The hour wheel 38 carries a jumper spring 50 which drives a star with twelve teeth 52 in steps of 1/12 (see FIG. 6). The star 52 is driven on an intermediate wheel 54 which itself carries a jumper spring 56 which drives in steps of 1/12 a star with twelve teeth 58 driven on the barrel 48. The operation of this mechanism will be described below .

The minute hand 16 of the true time is driven by a true time display gear comprising in particular a differential mechanism 60 which has for respective entries the roadway 36 on the one hand, and a rake 62 which cooperates with a cam equation of time 64 (see Figure 7). More specifically, the differential mechanism 60 comprises a planet wheel 66 which is driven by the roadway 36 and which carries one and, preferably, two planet gears 68. These two satellites 68 are able to turn on themselves and to roll on an internal toothing 70 of an equation wheel of the time 72. The latter also has on its outer periphery a toothing 74 by which it cooperates with the rake 62 and the equation cam of time 64. The differential mechanism 60 finally includes in its center an output mobile 76 formed of a pinion 78 carried by an axis 80 and which meshes with the planet gears 68. A wheel 82 is driven on the pinion 78 and meshes with an equation pavement 84 mounted freely on a canon 86 minutes of the true time which carries at its free end the needle 16 minutes of the true time. For a more complete description of the differential mechanism and its operation, reference will be made to European Patent Application EP 1 286 233 in the name of the Applicant, which is hereby incorporated by reference.

The equation pavement 84 drives in rotation, through a friction coupling 88, an additional roadway 90 fixed on the barrel 86 of the minutes of the true time and which constitutes one of the inputs of a second differential mechanism. This additional roadway 90 carries one and, preferably, two planet gears 94 which are able to turn on themselves and to roll on an internal toothing 96 of a longitude management wheel 98. This wheel for managing the longitude 98 also has on its outer periphery a toothing 100 by which it cooperates with a longitude correction mechanism 102 which will be described in detail below. The differential mechanism 92 finally comprises in its center an output pinion 104 integral with the gun 86 of the minutes of the true time and which meshes with the planet gears 94. The structure and operation of this second differential mechanism 92 are similar to those of the differential mechanism 60 described above. Therefore, for more details, one can also refer to the European patent application in the name of the Applicant mentioned above.

An additional equation pavement 106 is attached to the barrel 86 of the minutes of true time. This pavement 106 transmits the true time information to a mobile carrying the true hours hand 14 via a timer wheel 112 comprising a wheel 114 and a pinion 116 which achieve a reduction of 1/12. . The mobile carrying the true hours hand 14 comprises an equation board 108 and a real hours wheel 110. The real hours wheel 110 is fixed on a gun 118 of the hours of the true time which carries the real hours hand 14 at its free end. The wheel of the true hours 110 carries on the other hand a spring jumper 120 which drives in steps of 1/12 a star with twelve teeth 122 driven on the barrel 118.

We are now interested in the operation of the mechanism described above. Suppose first that the wearer of the watch is in the center of a time zone, for example on the meridian of Greenwich. In this case, no correction is to be made, both from the point of view of the shift of the civil time and the management of the longitude. The movement of the watch thus drives the wheel 34 mounted on the roadway 36 to provide an indication of the minute of the base time, ie the civil time in the center of the spindle. In turn, the roadway 36 transmits, via the timer wheel 42 and the hour wheel 38, the basic time information to the calendar hour wheel 40 to provide an indication of the time of the civil time. Simultaneously, the movement of the watch causes the differential mechanism 60 to provide an indication of the minute of the true time or solar time. In normal operation of the watch, the time equation cam 64 and the rake 62 are stationary. On the other hand, the planet gears 68 are driven by the roadway 36, that is to say by the clockwork movement of the watch. The pinions 68 therefore turn on themselves and roll on the internal toothing 70 of the equation wheel of the time 72, driving the output pinion 78 and the wheel 82 in rotation. The equation pavement 84 in turn rotates, driving the additional roadway 90 via the friction clutch 88, allowing the minute hand of the true time 16 to rotate concomitantly with the minute hand of the time. Civil 12. The gap between the needle 16 of the minutes of true time and the hand 12 of the minutes of the civil time therefore remains constant over a period of 24 hours. Once a day, around midnight, the equation cam of time 64 pivots, driven by a date mechanism 124 which changes the calendar from one day to the next. At this precise moment, the rake 62 pivots in turn, driving the equation wheel 72 in rotation. The Since the planet gears 68 are, during this brief time interval, substantially immobile (they make a complete revolution in one hour), they rotate on themselves while being rotated by the equation wheel of time 72, and cause them to rotate. turn the output pinion 78 so as to adjust again exactly the position of the minute hand of the true time 16. The information of the true time, as for it, is transmitted to the wheel of the true hours 110 by the additional equation pavement 106 via the timer mobile 112.

Suppose now that the user is no longer on the Greenwich meridian but in Switzerland, where the civil time is one hour ahead of Greenwich in winter, and two hours in summer. To know exactly when the sun goes to its zenith according to the civil time of the place where it is, the user will have to shift the calendar time indicated by his watch of one hour (or two hours in summer) compared to the base time which is the civil time in the center of the time zone. For this, the user has a correction pinion 126 which can be rotated in both directions and which drives the wheel of the civil hours 40 forwards or backwards in steps of 1/12. Indeed, the wheel of civil hours 40 is driven on the barrel of civil hours 48 which is itself associated with the star with twelve teeth 58 indexed in position by the jumper spring 56. This spring 56 has the general shape of a C and is provided at its two ends with a spout 128 which engages in a recess between two successive teeth of the star 58. Thus, by acting on the corrector pinion 126, is driven the wheel of the civil hours 40 and hence the star 58 which advances in successive jumps of a twelfth of a turn each time. It is therefore possible to correct the calendar time displayed by the watch to account for the difference between the civil time of the place where one is and the base time in the center of the spindle without changing the true solar time.

Suppose now that the user is in Geneva (Switzerland). In addition to the time difference in Switzerland from the base time in the center of the Greenwich time zone, the difference in longitude between Geneva and Greenwich must also be taken into account. In this case, Geneva is located at 6 ° and 10 minutes east longitude compared to Greenwich, which means that the sun is 25 minutes ahead of Geneva time. On 23 December, when the difference between true solar time and civil time is zero and the Geneva time is one hour ahead of the Greenwich hour (winter time), the watch will indicate 12h 35min in Geneva during the passage of the sun to its zenith. In order to take into account the difference in longitude between the user's location and the center of the time zone in which this location is located, the user has a device for defining the longitude 130 which enables him to to indicate whether found in the system of longitudes is (E) or west (W). The transition from the longitudes system is (E) to the west longitudes system (W) and conversely causes a change in the direction of rotation of the 16 minutes hand of true time as described below. It must be understood that a displacement in the direction of longitudes is (E) corresponds to a reverse displacement in the direction of longitudes west (W). For example, someone who moves +6Ε from Greenwich will see the sun at zenith at 11h 36min, while moving + 6 ° W from Greenwich will see the sun at its zenith at 12h 24min . Before changing the longitudes system, the needle 26 of the longitude management mechanism must be zero.

The longitude defining device 130 comprises control means (not shown) by means of a pusher (column wheel and shuttle) or by a rod with two stable pulled positions. These control means act on an inverter which, in a preferred embodiment of the invention, comprises a flip-flop 131 (see FIGS. 8A and 8B) able to pass alternately from a first stable position in which it indicates the system of longitudes. is (E) at a second stable position in which it indicates the west longitudes system (W). This rocker is pivotally mounted about an axis 132 of a return wheel 133 and carries a second return 134 as well as a wheel 136 which are in permanent engagement. According to one variant, the flip-flop 131 carries two indicator elements 135 such as red-colored pellets which are intended to appear through two corresponding windows in the dial of the watch and which indicate to the user which of the two systems of longitudes is (E) or west (W) he selected. In the first stable position of the latch 131 shown in FIG. 8A, the reference 133 meshes with the longitude management wheel 98 via the reference 134 and the wheels 136 and 138. The wheel 138 is limited in its rotation. by a pin 140 so that the needle 26 can rotate more than 180 ° clockwise or anti¬clockwise. By rotating the reference 133 in the counterclockwise direction, the user causes a rotation in the same direction of the wheel 98 for managing the longitude, this rotation being limited to a maximum of 180 ° by the wheel 138. In the second Stable position of the latch shown in Figure 8B, the wheel 136 is decoupled from the wheel 138, so that the reference 133 meshes with the wheel 98 for managing the longitude via the reference 134 and the wheel 138 only. By turning the reference 133 counter-clockwise, the user causes a rotation in the opposite direction of the longitude management wheel 98, this rotation being limited to a maximum of 180 ° by the wheel 138. Thus, in turning the reference 133 always in the same direction, the user can rotate, forwards or backwards, the minute hand 16 minutes of true time depending on whether it is in the longitudes system is (E) or west (W).

Suppose, then, that the user is in Geneva, that is, at +6 ° east longitude (E) with respect to the meridian of Greenwich. As described above, the user can, by means of the longitude defining device 130, move the needle 30 so as to point it to the east (E), then display an offset of + 6 ° in longitude by means of the needle 26. This needle 26 is carried by the wheel 138 which is driven, forwards or backwards, by a maximum value of +/- 30min corresponding to a variation of +/- 7.5 ° in longitude with respect to the center of the spindle (see Figure 9). The wheel 138 is limited in its rotation by a pin 140 so that the needle 26 can not rotate more than 180 ° clockwise or counter-clockwise. This wheel 138 meshes with the external toothing 100 of the longitude management wheel 98 which, by rotating, rotates the planet gears 94. The latter in turn drive the output pinion 104 integral with the barrel 86 of the minutes of true time. By turning, the barrel 86 of the minutes of the true time rotates the additional roadway 90 which, by means of the friction coupling 88, slides on the equation pavement 84, which allows the momentary deindexing of the minute of the true time. Each degree of displacement of the needle 26 which indicates the offset in longitude relative to the center of the spindle corresponds to four minutes of displacement of the needle 16 minutes of the true time.

If the user is within + 6 ° east longitude (E) relative to the Greenwich meridian, the display of this offset using the longitude management mechanism causes the minute hand rotation of the true time counter-clockwise 24 minutes. Conversely, if the user is at + 6 ° west longitude (W) relative to the Greenwich meridian, displaying this offset using the longitude management mechanism will cause the minute hand to rotate. true time clockwise 24 minutes.

Now suppose the user changes timezone. It is interesting for him to be able to index the time and date of his watch simply and quickly.

For this, it has a correction pinion 142 which simultaneously rotates in one hour increments the intermediate wheel 54 and the wheel of the true hours 110. On the intermediate wheel 54 is driven the star with twelve teeth 52 whose The position is indexed by the jumper spring 50 which is of the same type as the jumper spring 56 described above. Thus, by acting on the corrector pinion 142, the intermediate wheel 54 and thereby the star 52 are driven which advance in successive jumps of one twelfth of a turn each time. By turning, the intermediate wheel 54 drives the star The display of the calendar time is therefore corrected for the number of hours corresponding to the time difference between the location of the user and the reference timezone. The true hour wheel 110 also advances in successive jumps of a twelfth of a revolution, its movement being indexed by the jumper spring 120 which is engaged with the star 122 driven on the barrel 118 of the hours of the true time. The hour hand of the civil time and the hour hand of the true time therefore move concomitantly without the minute of the true time being changed.

Suppose the user is at 25 ° east longitude (E). The multiple of 15 closest to 25 is 30 so the user will have to display -5 ° by means of the needle 26 of the longitude management mechanism. If the user is at 32 ° east longitude (E), the multiple of 15 closest to 32 being 30, the user will have to display a + 2 ° difference on the longitude management mechanism.

The date mechanism, simple or perpetual, can be of any known type and will not be described in its entirety. It is sufficient, in fact, for a good understanding of the invention, to know that this date mechanism results in the time equation cam 64 at a rate of one complete revolution per year. However, it is shown for illustrative purposes only (see Figure 10), a date mobile 144 driving the needle 6 indicating the date (1 to 31). This date mobile 144 rotates at a rate of one complete turn per month. It is actuated by the date mechanism via an intermediate date wheel 146 for reversing the direction of rotation, and a reduction wheel 148 which reduces the speed of rotation of a complete revolution per month to one revolution complete per year. It goes without saying that the present invention is not limited to the embodiment which has just been described and that various modifications and simple variants can be envisaged by those skilled in the art without departing from the scope of the invention as defined by the appended claims.

Claims

A timepiece comprising a watch movement and a date mechanism (124), this timepiece having a pair of hour and minute hands (10, 12) which indicate the calendar time, and an additional minute hand (16) which indicates the true minute and which is driven by a true time display gear, the daily position of the minute hand (16) of the true time being determined by the position of a time equation cam (64) driven in rotation at the rate of one revolution per year from the date mechanism (124), characterized in that the display gear of the true time causes a mobile carrying a needle of the overtime (14) which indicates the true time and in that an equation pavement (84) mounted free on a barrel (86) of the minutes of the true time at one end of which is fixed the needle (16) of minutes of true time rotates through a hug frictionally (88) an additional roadway (90) attached to the barrel (86) minutes of true time.

2. Timepiece according to claim 1, characterized in that the display gear of the true time drives the mobile bearing the true hour hand (14) via an equation pavement (106) fixed on the barrel ( 86) minutes of true time.

3. Timepiece according to claim 2, characterized in that the roadway (106) transmits the information of the true time to an equation board (108) and then to a true hour wheel (110) by the intermediate of a timer wheel (112) which achieves a reduction of 1/12, the true hour wheel (110) being fixed on a gun (118) hours of true time which carries at a free end the needle true hours (14).

4. Timepiece according to claim 3, characterized in that the equation board (108) carries a jumper spring (120) which drives in steps of 1/12 a star with twelve teeth (122) driven on the barrel (118).

5. Timepiece according to any one of claims 2 to 4, characterized in that the display gear of the true time comprises a differential mechanism (60) which has respective entries a roadway (36) at an end of which is fixed the needle (12) of the minutes of the civil time and a rake (62) which cooperates with the equation of time cam (64).

6. Timepiece according to claim 5, characterized in that the differential mechanism (60) comprises a wheel (66) which is driven by the roadway (36) and which carries at least one planet gear (68) able to rotate on himself and rolling on an internal toothing (70) of a time equation wheel (72), this time equation wheel (72) also having an external toothing (74) by which it cooperates with the rake (62).

7. Timepiece according to claim 6, characterized in that the differential mechanism (60) comprises at its center an output gear (78) which meshes with the pinion satellite (68).

8. Timepiece according to claim 7, characterized in that a wheel (82) is driven on the pinion (78) and meshes with the equation pavement (84).

9. Timepiece according to any one of claims 1 to 8, characterized in that the additional roadway (90) is one of the inputs of a second differential mechanism (92), the other input of the differential mechanism (92) being constituted by a longitude correction mechanism (102).

Timepiece according to claim 9, characterized in that the additional roadway (90) carries at least one planet gear (94) able to turn on itself and to roll on an internal toothing (96) of a longitude management wheel (98), said longitude management wheel (98) also having an outer toothing (100) by which it cooperates with the longitude correction mechanism (102).

11. Timepiece according to claim 10, characterized in that the differential mechanism (92) comprises in its center an output pinion (104) integral with the barrel (86) minutes true time and which meshes with the pinion satellite (94).

Timepiece according to any one of claims 9 to 11, characterized in that the longitude correction mechanism (102) comprises a wheel (138) which can be driven forwards or backwards and which is limited in its rotation so that it can not turn more than 180 ° clockwise or counter-clockwise.

13. Timepiece according to any one of claims 9 to 12, characterized in that it comprises a device for defining the longitude (130) which allows a user to indicate if it is in the system of longitudes is (E) or west (W) and which cooperates with the longitude correction mechanism (102) so as to cause a change in the direction of rotation of the needle (16) of the minutes of the true time.

14. Timepiece according to claim 13, characterized in that the longitude defining device (130) comprises a mechanical inverter.

Timepiece according to Claim 14, characterized in that the device for defining the longitude (131) comprises a rocker (131) which can occupying two distinct stable positions respectively corresponding to the systems of longitudes is (E) and west (W), this rocker (131) carrying a reference (134) and a wheel (136) which are permanently engaged, the reference (134) meshing either directly or via the wheel (136) with the longitude management wheel (98) according to the position occupied by said flip-flop (136).

Timepiece according to any one of claims 1 to 15, characterized in that the movement transmits the civil time information to an hour wheel (38) and then to a calendar hour wheel (40). by means of a timer wheel (42) which achieves a reduction of 1/12, the calendar hour wheel (40) being driven on a gun (48) which carries at a free end the needle (10) civilian hours.

17. Timepiece according to claim 16, characterized in that the hour wheel (38) carries a jumper spring (50) which drives a star with twelve teeth (52) in steps of 1/12, this star (52). ) is driven on an intermediate wheel (54) which itself carries a jumper spring (58) which drives in steps of 1/12 a star with twelve teeth (58) driven on the barrel (48).

18. Timepiece according to claim 17, characterized in that it comprises a correction pinion (142) which simultaneously rotates forward or backward in steps of one hour the intermediate wheel (54) and the wheel of true hours. (110).

19. Timepiece according to any one of claims 16 to 18, characterized in that it comprises a correction pinion (126) which can be rotated in both directions and which drives the wheel of the calendar hours (40). ) forward or backward in steps of 1/12 without changing the solar time.