CH711317A2 - Chronograph mechanism with retrograde rattrapante. - Google Patents

Abstract

The present invention relates to a retrograde chronograph mechanism for a watch movement (1) for providing, on demand, retrograde driving of a first display unit of a unit of a measured time, preferably seconds. a measured time, the mechanism also comprising a split-seconds mobile intended to carry a second display member of the same unit of a measured intermediate time, a split-seconds counter connected to the chronograph counter (8) via a disengageable indexing device, a retrograde drive device of the retractable mobile having a kinematic connection with the retrigger counter, and a locking device (66, 68) at the request of the divider counter to enable the retractor. intermediate time display measured.

Description

Technical area

The present invention relates to a retrograde chronograph mechanism for a watch movement, intended to ensure, on demand, the retrograde drive of a first display unit of a unit of a measured time, preferably seconds of a measured time.

This mechanism comprises a chronograph counter, a clutch device for establishing, on demand, a connection between the chronograph counter and a driving wheel of the watch movement, a chronograph mobile for carrying the first display member, a retrograde drive device of the chronograph mobile having a kinematic connection with the chronograph counter.

State of the art

[0003] Few timepieces have been presented so far which include a chronograph mechanism with retrograde display of at least one unit of a measured time.

By way of example, the patent application WO 2005/091 086 A1 describes and illustrates a timepiece with electronic movement arranged to present a retrograde display tenths of seconds and a retrograde display hundredths of seconds . Because of the use of an electronic movement, it is clear that this invention lies more in the manner of presenting the information than in the construction that achieves the desired display.

The patent application EP 1 024 416 A2 describes another example of chronograph mechanism, mechanical this time. The purpose of the construction presented in this application is to control a display of fractions of measured seconds of time and to take up typical elements of mechanisms used to make retrograde displays. However, in this case, the display unit of fractions of seconds does not exactly follow a retrograde movement, in the conventional sense, insofar as the display of the number of fractions of seconds measured is done on demand, whereas the mechanism is stopped to avoid any risk of damage.

More recently, the Hublot brand has introduced several models of mechanical watches containing the same movement comprising a bi-retrograde chronograph mechanism, within a collection called Big Bang Unico Bi-Retrograd Chrono. This watch movement is arranged to control the movements of retrograde display hands of seconds and minutes of time measured. The two needles move opposite two concentric graduated sectors.

[0007] It can be seen that few major novelties are presented by watchmakers in connection with chronograph mechanisms. This is particularly due to the fact that these mechanisms are among the most difficult to develop and, in particular, they must be perfectly adjusted to present a display quality sufficient to be implemented in timepieces of top of the line. Most inventions relating to chronograph mechanisms also relate to known constructions and aims to improve the operation and / or reliability or to simplify the development.

There is, however, a constant need to create innovative products in the field of watchmaking, in particular to seduce customers by offering exclusive timepieces and practical use, in particular whose readability is good.

Disclosure of the invention

A main object of the present invention is to provide a chronograph mechanism of the type mentioned above, that is to say with retrograde display, representing an important technical advance in the field of chronograph mechanisms by the implementation. a rare complication taking a novel form and ensuring a good readability of the information provided by the corresponding timepiece.

For this purpose, the present invention relates more particularly to a chronograph mechanism corresponding to the characteristics mentioned above, characterized in that it comprises a catch-up mobile intended to carry a second display unit of the unit of a measured intermediate time, a catch-up counter connected to the chronograph counter by means of a disengageable indexing device, a retrograde drive device of the jumper mobile having a kinematic connection with the counter-split counter, and a latching device at the request of the split counter to allow the display of the measured lap time.

Split-chronograph mechanisms are relatively rare and are even more complex to develop than conventional chronograph mechanisms. Typically, the catch-up mechanism controls the movements of a second display hand of a measured intermediate time which is positioned under the second chronograph hand, being pivoted to the center of the dial of the corresponding timepiece. . The readability of these watches is often reduced as we finally end up with four hands pivoted in the center, with those of minutes and hours.

With the features of the present invention, that is to say the implementation of a retrograde retrograde needle, it becomes possible to associate such a needle to a retrograde chronograph mechanism and to provide a specific display area for measured times. The legibility of the corresponding timepiece can thus be improved with reference to known timepieces. It is possible to arrange the two needles in such a way that they are superimposed as is the case usually, but one can also consider, as an alternative, a specific display sector for each of the hands if the occupation of the dial by other functions of the timepiece allows it.

Advantageously, the retrograde drive device of the chronograph mobile comprises a chronograph cam rotated from the chronograph counter and associated with a chronograph rocker carrying, on the one hand, a probe maintained in support against the chronograph cam and, secondly, a chronograph rake having a kinematic link with the chronograph mobile. In a similar manner, the retrograde drive device of the retractable wheel comprises a retracting cam driven in rotation from the split-seconds counter and associated with a catch-up flip-flop bearing, on the one hand, a probe held in abutment against the cam. on the other hand, on the other hand, a catch-up rake having a kinematic connection with the split-seconds mobile.

These characteristics allow the watch manufacturer to have the various components of the mechanism almost anywhere in the watch movement, and allow him to take into account the constraints inherent in other components of the movement with great flexibility.

It is also possible that the chronograph counter includes a first chronograph wheel, the retrograde drive device of the chronograph mobile comprising a second chronograph wheel integral in rotation with the chronograph cam, the first and second wheels of the chronograph wheel. chronograph being arranged in engagement with each other. In addition, it is then possible to provide for the split-timer counter to comprise a first split-second wheel, the retrograde-drive device for the split-second mobile comprising a second split-second wheel arranged for rotating the split-second cam, the first and second wheels. catches being arranged in engagement with each other.

Preferably, the first chronograph wheel and the first catch-up wheel are coaxial.

In this case, it can be provided that the disengageable indexing device comprises a core cam integral with the first chronograph wheel and against which is held in support a probe carried by a lever pivotally mounted on the first wheel of the second .

Similarly, it can be provided that the second chronograph wheel and the second split wheel are coaxial.

In an alternative embodiment, it is possible to provide that the second split-second wheel is rotatably connected to a third catch-up wheel itself arranged in engagement with a catch-up journal integral in rotation with the split-second cam. .

According to a preferred embodiment of the invention, provision is made for the on-demand locking device of the split-timer counter to comprise a pair of clamps arranged for pivoting between a locked position, in which the tongs act simultaneously on the first split wheel to lock it, and an unlocked position, in which the clamps are located at a distance from the first catch-up wheel to allow the latter to rotate freely.

In this case, it is advantageous to further provide that the first idler wheel has a sufficient thickness to cooperate, on the one hand, with the clamps and, secondly, with the second split-second wheel in respective plans superimposed. Thanks to this characteristic, the small deformations that the teeth of the first split-second wheel is likely to suffer due to the shocks of the clamps do not risk compromising the quality of its meshing with the second split-second wheel.

Preferably, the chronograph counter comprises a cam in the heart, reset, rotatably connected to the first chronograph wheel, the counterclockwise counter and the retrograde drive device of the mobile rattrapante being arranged from such that the splitter cam has a rotation frequency equal to twice the rotation frequency of the first chronograph wheel. In this case, the chronograph cam has a rotation frequency equal to that of the first chronograph wheel. In addition, the catch-up cam preferably has the shape of a simple snail while the chronograph cam has the shape of a double snail.

Furthermore, according to an alternative embodiment, one can also provide that the mechanism comprises an insulator integral with one of the chronograph and catch-up scales, and arranged to act on the other, so that their fall on the cams, respectively chronograph and split, are synchronized.

The present invention also relates to a watch movement with a chronograph mechanism responding to the features just presented, and a timepiece equipped with such a watch movement.

Brief description of the drawings

Other features and advantages of the present invention will appear more clearly on reading the detailed description of a preferred embodiment which follows, made with reference to the accompanying drawings given by way of non-limiting examples and in which : <tb> Fig. 1 <SEP> represents a simplified front view of a part of a watch movement, illustrated with its visible dial side, comprising a chronograph mechanism according to a preferred embodiment of the invention; <tb> fig. 2 <SEP> represents a simplified front view of a first construction detail of the watch movement of FIG. 1, and <tb> fig. 3 <SEP> represents a simplified front view of a second construction detail of the watch movement of FIG. 1.

Mode (s) of realization of the invention

Fig. 3 1 represents a simplified front view of a watch movement 1 comprising a chronograph mechanism according to a preferred embodiment of the invention, the movement being illustrated with its visible dial side. Fig. 2 represents a front view of a construction detail of the watch movement of FIG. 1, while FIG. 3 represents a complementary front view of a second construction detail of the watch movement of FIG. 1 which is not visible in FIGS. 1 and 2 .

The watch movement 1 comprises a plate 2 for supporting the movement components including certain components of the chronograph mechanism according to the invention. According to the construction of the movement, the plate 2 may also be an auxiliary plate dedicated to the chronograph mechanism and, in this case, a main plate (not shown) located under the auxiliary plate would support the other components of the movement.

The watch movement 1 will not be described in detail in that many of the elements that compose it do not have a direct impact on the implementation of the present invention.

In the present preferred embodiment, by way of nonlimiting illustration, the watch movement 1 is of the type comprising at least two needles (not shown) for displaying the current hours and minutes. These needles are here intended to be off-center towards the midday position. Moreover, the watch movement 1 is arranged to control the movements of a second chronograph seconds hand and a second seconds hand (shown in Fig. 3), that is to say a needle intended for display the measured seconds of intermediate time. Preferably, the watch movement 1 is also intended to cause the movements of hands minutes minutes and hours of time measured (not shown). It comprises a source of energy (not visible) intended to cause the movement of these needles through including a finishing train (not visible). Of course, the watch movement 1 may include complications associated with additional display members without departing from the scope of the present invention.

In a non-limiting manner, the watch movement 1 is here intended to equip a pocket watch comprising a first control member 4, chronograph, at noon and a second control member 6, of the rattrapante, at eleven o'clock.

The chronograph mechanism illustrated here is of the monopusher type, that is to say that the first control member 4 can control all operating modes of the chronograph mechanism alone, sequentially, in the order: walk, stop then reset. In the absence of action on the second control member 6, the split-second hand has the same movement as the second chronograph hand.

At first, the part of the watch movement illustrated relative to the operation of the basic chronograph will be described. The specific operation part of the catch-up mechanism will be described in a second step.

The chronograph mechanism comprises a chronograph counter 8, seconds, arranged here in the center of the watch movement 1. The chronograph counter 8 is capable of being rotated from an average wheel 10 of the movement watchmaker, via a conventional clutch device 12.

The clutch device 12 comprises a seconds wheel 14, pivoted on a bridge 16 and secured to a pinion (not visible) so that it makes a turn on itself in two minutes. A clutch wheel 18 carried by a clutch rocker 20 is arranged in permanent engagement with the seconds wheel 14. The clutch rocker 20 is pivotable between an engaged position, in which the clutch wheel 18 engages also with a first chronograph wheel 22 of the chronograph counter 8, and a disengaged position in which the clutch wheel 18 is located out of reach of the first chronograph wheel 22.

When the clutch rocker 20 is in the engaged position, the first chronograph wheel 22 is driven at the rate of one revolution in two minutes.

The first chronograph wheel 22 is arranged in permanent engagement with a second chronograph wheel 24, pivotally mounted in particular on a retrograde bridge 26 and forming part of a retrograde drive device chronograph seconds.

The second chronograph wheel 24 is integral in rotation with a chronograph cam 28, in the form of double snail.

An additional board (not visible) is partially arranged in superposition of the retrograde bridge 26 to ensure the assembly of components of the retrograde drive device, as illustrated in FIG. 3.

A chronograph rocker 30 is arranged in rotation on the additional plate, the latter comprising a feeler 32 intended to be arranged in abutment against the periphery of the chronograph cam 28 and a toothed rake 34. The latter is arranged in taken with a chronograph mobile 36, coaxial with the chronograph counter 8 and intended to carry a needle 38 seconds of measured time.

With this construction, when the clutch device 12 is in the engaged configuration, the rotation of the average wheel 10 is transmitted to the second chronograph wheel 24, and therefore to the chronograph cam 28 which rotates at the right time. a full turn in two minutes.

A graduated sector of measured seconds of time 40 is shown diagrammatically in FIG. 3, which extends over an angle of 140 degrees, by way of nonlimiting illustration. The shape of the chronograph cam 28 and the reduction ratio between the chronograph rake 34 and the chronograph mobile 36 are such that the chronograph hand 38 travels at a 140 degree angle when the chronograph cam 28 makes a U-turn, once every minute. Then, the feeler 32 falls on the portion of the chronograph cam 28 having the smallest radius and the chronograph hand 38 returns to its initial position, before repeating the same movement as long as the measurement of a time is in progress .

An elastic return member (not shown) is provided to act on the chronograph rocker 30 and maintain its probe 32 bearing against the periphery of the chronograph cam 28.

At the same time, the chronograph mechanism also provides the drive of a chronograph minute counter 42 in a conventional manner. The chronograph mechanism comprises for this purpose two drive fingers 44, diametrically opposed and integral in rotation with the first chronograph wheel 22, these fingers being intended to advance a step forward a minute 46 each time the Mobile Chronograph 36 travels at an angle of 140 degrees, ie once a minute. The return of the minutes 46 in turn causes a wheel 48 of the minute counter 42 once per minute.

Furthermore, the chronograph counter 8 also comprises a cam 49 in conventional reset, secured to the first chronograph wheel 22.

Regarding the actuation of the chronograph mechanism, the first control member 4 cooperates with a column wheel 50 three times to rotate and switch from one operating mode to another. The columns of the column wheel 50 conventionally cooperate with a spout 51 of the clutch rocker 20, with a brake 52 of the chronograph counter 8 and with a reset hammer 54. The latter comprises first and second arms 56, 58 arranged to act respectively on the seconds counter 8 and on the minutes counter 42. Elastic return members are provided, in known manner, to act on these various components and tend to push them back into their position. by default. Similarly, jumpers are provided to maintain the angular positions of the column wheel 50 and the minute counter 42, when necessary.

The structure and operation of the catch-up mechanism will now be described.

The catch-up mechanism comprises a split-second counter comprising a first split-second wheel 60 which is coaxial with the first chronograph wheel 22. It furthermore comprises a disengageable indexing device arranged between the first chronograph and split-seconds wheels. such that the angular position of the first split wheel 60 can be indexed to that of the first chronograph wheel 22 when necessary.

More specifically, this disengageable indexing device comprises, in a conventional manner, a heart cam (not visible) integral with the first chronograph wheel 22 and a lever 62 pivotally mounted on the first split wheel 60, the lever 62 having a feeler (not visible, or a roller, alternatively) held in abutment against the periphery of the heart cam under the effect of the action of a spring 64 also carried by the first wheel of split-seconds 60,

Thus, when the measurement of a time is in progress, the first split-second wheel 60 follows the first chronograph wheel 22.

A pair of conventional splitters 66 is provided to lock the first split wheel 60 when the reading of an intermediate measured time is requested by the user. The clamps 66 are movable between a locked position, in which they are arranged in abutment against the toothing of the first split wheel 60, and an unlocked position in which they leave the first split wheel 60 free to rotate.

The grippers 66 are controlled in synchronization, in a known manner, by a column wheel 68 of the retractor arranged to be rotated, step by step, by the second control member 6, to change the state of the grippers, alternately.

Furthermore, the first split-second wheel 60 has a permanent kinematic link with a retrograde counter-clockwise drive device, meshing with a second split-second wheel 70.

Note that, advantageously, the thickness of the first split wheel 60 is such that, on the one hand, the clamps 66 and secondly the second split wheel 70 cooperate with it to different levels of its teeth, in respective superimposed planes. Thus, even if a portion of the teeth of the first split-second wheel 60 would be damaged by repeated impacts of the tongs, this could not disturb the operation of the mechanism since the transmission between the first and second split-seconds wheels intervenes. with a part of the toothing that never comes into contact with the clamps.

The second catch-up wheel 70 is coaxial with the second chronograph wheel 24 and is rotationally integral with a third catch-up wheel 72, also coaxial, but of smaller diameter.

As is apparent from FIG. 3, the third catch-up wheel 72 is arranged in engagement with a catch-up return 74 integral in rotation with a split snail cam 76 in the shape of a single snail. The ratios between the second and third split-seconds wheels and the split-back gear are such that the split-second cam 76 performs a complete turn on itself in one minute.

A catch-up flip-flop 78 is arranged in rotation on the additional board, the latter comprising a feeler 80 intended to be arranged in abutment against the periphery of the split-second cam 76 and a toothed rake 82. The latter is arranged in taken with a rattrapante mobile 84, coaxial with the chronograph counter 8 and intended to carry a needle 86 of the seconds of measured intermediate time, called a catch-up.

With this construction, when the clutch device 12 is in the engaged configuration, the rotation of the average wheel 10 is transmitted to the second split wheel 70, and therefore to the split cam 76 which rotates right. a full turn in one minute.

A graduated sector of the measured intermediate time seconds 88 is shown schematically in FIG. 3, which extends over an angle of 140 degrees opposite to the graduated sector 40 of the measured seconds of time, by way of nonlimiting illustration. The shape of the split-second cam 76 and the reduction ratio between the split-second rake 82 and the split-seconds wheel 84 are such that the split-second needle 86 travels at a 140-degree angle when the split-second cam 76 makes a complete turn, either once every minute. Then, the probe 80 falls on the portion of the splitter cam 76 having the smallest radius and the split-second needle 86 returns to its initial position, before repeating the same movement as long as the measurement of a time is in progress .

An elastic return member (not shown) is provided to act on the catch-up latch 78 and maintain its probe 80 bearing against the periphery of the split-second cam 76.

This construction makes it possible to obtain an operation of the split-second needle similar to that of the known watch mechanisms, with the difference that it presents a retrograde movement here. In particular, when the grippers 66 are in their unlocked position, the split-second needle 86 has displacements similar to those of the chronograph hand 38 in all operating modes of the chronograph mechanism (on, off, reset). ), while it remains stationary in all modes of operation when the clamps are in their locking position.

The split-second needle 86 may be arranged to move with respect to the same graduated sector as the second chronograph hand 38 or, alternatively, on a sector which is specific to it as illustrated in FIG. 3.

Advantageously, an isolator 90 may be provided between the chronograph and catcheswitch latch 78, here having the shape of a curved spring whose one end is integral with the chronograph rocker 30 and the other end is arranged in support against a pin 92 carried by the catch-up latch 78. This isolator 90 ensures perfect synchronization between the two flip-flops when they fall on the corresponding cams. Specifically, the chronograph rocker 30 retains the latch rocker 78 until it has fallen. It is only at the moment of its fall that the insulator 90 releases the catch-up latch 78 and also allows it to fall on the portion of the split-second cam 76 of the weakest radius.

Thanks to the characteristics that have been exposed, a timepiece having an original chronograph display can be achieved, not only the latter being retrograde type, but in addition it is associated with a display of intermediate times also of retrograde type.

The foregoing description attempts to describe a particular embodiment by way of non-limiting illustration and, the invention is not limited to the implementation of certain particular features which have just been described, as for example the number of wheels and / or referrals described in the chronograph and ratchet workings. Indeed, it is possible to provide different wheels that could possibly have the chronograph displays and catches in other parts of the dial of the corresponding timepiece, without departing from the scope of the invention, these displays whether or not they are superimposed.

As an alternative to the implementation of a difference in rotation frequency between the first chronograph wheel 22 and the split-second cam 76, it is possible to provide that the feeler 80 of the split-seconds rocker 78 is provided with a security to allow it to retract if the reset chronograph was to cause a rotation of the cam follower 76 in the counterclockwise direction in the view of FIG. 3.

The skilled person will not encounter any particular difficulty to adapt the content of the present disclosure to his own needs and to implement a timepiece that only partly meets the described characteristics but includes a mechanism for Chronograph arranged to drive chronograph and retrograde chronograph hands, without departing from the scope of the invention.

The present teaching may also be adapted to provide the drive of a display member associated with a unit of time other than the second without departing from the scope of the invention.

Claims (16)

1. Retrograde chronograph mechanism for a watch movement (1) for providing, on demand, retrograde driving of a first display member (38) of a unit of a measured time, preferably seconds measured time, the mechanism comprising a chronograph counter (8), a clutch device (12) for establishing, on demand, a connection between said chronograph counter (8) and a driving wheel (10) of the watch movement (1), a chronograph wheel (36) for carrying the first display member (38), a retrograde driving device of said chronograph mobile (36) having a kinematic connection with said chronograph counter (8), characterized in that it comprises a catch-up mobile (84) for carrying a second display member (86) of said unit with a measured intermediate time, a catch-up counter connected to said chronograph counter (8) via a disengageable indexing device (62, 64), a retrograde driving device of said jumper wheel (84) having a kinematic connection with said counter-clock counter, and a latch (66, 68) at the request of said split counter to allow the display of the measured split time. 2. Mechanism according to claim 1, characterized in that said retrograde driving device of said chronograph wheel (36) comprises a chronograph cam (28) driven in rotation from said chronograph counter (8) and associated with a chronograph scale (30) carrying, on the one hand, a feeler (32) held in abutment against said chronograph cam (28) and, on the other hand, a chronograph rake (34) having a kinematic connection with the chronograph wheel (36), and in that said retrograde driving device of said shifter wheel (84) comprises a shifter cam (76) rotated from said countertractor counter and associated with a counterbalance latch (78) carrying, on the one hand, a feeler (80) held in abutment against said split-second cam (76) and, on the other hand, a split-second rake (82) having a kinematic connection with the split-seconds mobile (84). 3. Mechanism according to claim 2, characterized in that said chronograph counter (8) comprises a first chronograph wheel (22), said retrograde driving device of said chronograph mobile (36) comprising a second chronograph wheel (24) rotationally integral with said chronograph cam (28), said first and second chronograph wheels (22, 24) being arranged in engagement with one another and, in that said catch-up counter comprises a first catch-up wheel (60), said retrograde drive device of said divider carrier (84) comprising a second catch-up wheel (70) arranged to rotate said cam of catches (76), said first and second catch-up wheels (60, 70) being arranged in engagement with each other. 4. Mechanism according to claim 3, characterized in that said first chronograph wheel (22) and first catch-up wheel (60) are coaxial. 5. Mechanism according to claim 4, characterized in that said releasable indexing device comprises a core cam integral with said first chronograph wheel (22) and against which is held in abutment a probe carried by a lever (62) mounted pivoting on said first catch-up wheel (60). 6. Mechanism according to one of claims 3 to 5, characterized in that said second chronograph wheel (24) and second split wheel (70) are coaxial. 7. Display mechanism according to one of claims 3 to 6, characterized in that said second spacer wheel (70) is integral in rotation with a third catch-up wheel (72) itself arranged in engagement with a split-spring return (74) integral in rotation with said split-second cam (76). 8. Mechanism according to one of claims 3 to 7, characterized in that said lock device at the request of said split counter comprises a pair of clips (66) arranged to pivot between a locked position in which said grippers (66) act simultaneously on said first catch-up wheel (60) to lock it, and an unlocked position in which said grippers (66) are spaced apart from said first split wheel (60) to allow the latter to rotate freely, and in that said first catch-up wheel (60) has a sufficient thickness to be able to cooperate, on the one hand, with said clamps (66) and, on the other hand, with said second catch-up wheel (70) in respective planes bunk. 9. Mechanism according to one of claims 3 to 8, said chronograph counter (8) comprising a core cam (49), reset, integral in rotation with said first chronograph wheel (22), characterized in that said catch-up counter and said retrograde driving device of said shifter wheel (84) are arranged in such a way that said shifter cam (76) has a rotation frequency equal to twice the rotation frequency of said first wheel of chronograph (22), said chronograph cam (28) having a rotation frequency equal to that of said first chronograph wheel (22). 10. Mechanism according to claim 9, characterized in that said cam follower (76) has the shape of a simple snail while said chronograph cam (28) has the shape of a double snail. 11. Mechanism according to one of claims 2 to 10, characterized in that it comprises an insulator (90) integral with one of said chronograph and catch-up latch (30, 78) and arranged to act on the other such that their fall on said cams, respectively of chronograph and splitter (28, 76), are synchronized. 12. Mechanism according to one of claims 1 to 11, characterized in that the second display member (86) is arranged to move with respect to the same sector graduated as the first display member (38). 13. Mechanism according to one of claims 1 to 11, characterized in that the second display member (86) and the first display member (38) move opposite distinct graduated sectors. 14. Watch movement (1) comprising a chronograph mechanism according to one of the preceding claims. 15. Watch movement (1) according to claim 14, when said chronograph (36) and catch-up (84) mobiles are intended to allow the display of seconds of a measured time, respectively of a measured intermediate time, characterized in that said drive wheel comprises an average wheel (10) arranged in engagement with a second wheel (14) turning on itself in two minutes and arranged to be kinematically connected to said first chronograph wheel ( 22), on demand, through said clutch device (12). 16. Timepiece housing a watch movement (1) according to claim 14 or 15 arranged to drive, on demand, a first display member (38) of a unit of a measured time and a second display member (86) of the same unit of a measured intermediate time.