EP1544692B1 - Electromechanical timepiece comprising a power reserve indicator - Google Patents

Description

TECHNICAL AREA

The present invention relates generally to a timepiece with micro-generator with power reserve indicator. The invention relates more particularly to the means for providing this power reserve indication. It also describes the method used to indicate the power reserve.

TECHNOLOGICAL BACKGROUND

It is known from the prior art, in particular from the document EP 0 762 243 in the name of the present Applicant, a timepiece, represented in FIG. 1, comprising a source of mechanical energy formed by a cylinder 1 in which is housed a spring 1a, manual or automatic winding, the winding device is not shown here.

The barrel 1 is mechanically coupled to the magnetized rotor 2a of an electric generator 2 via gear 3. The generator 2 comprises at least one coil 2b from which is generated an alternating voltage Ug, when the magnetized rotor 2a is driven by rotation, generating a magnetic field symbolized by means of an arrow and with which is coupled said at least one coil 2b.

The terminals of the coil 2b (or coils) are connected to a rectifier 4 outputting a rectified voltage Ua for supplying the regulator circuit 6, which will be discussed below.

Analogical elements for displaying a time indication 5, typically a set of hands or any other conventional means of mechanical time display, are mechanically coupled to the barrel through the gear trains 3 of the movement and are integral in rotation of the rotor 2a. The rotation speed of the needles 5 is maintained at a constant mean value by means of the regulator circuit 6, which is intended to slave the frequency of the generator to a reference frequency, so that the speed of the hands corresponds to the speed required to obtain a correct indication of the time.

This regulator circuit 6, will not be described in detail here, the skilled person can build such a control device by referring to the description of the Swiss patent application No. 686 332 in the name of the present Applicant. However, to make easier its understanding, we will recall here the essential elements of this circuit and its operation.

This regulator circuit 6 comprises a clock-stabilized oscillator 6a of a watchmaker-type quartz and a frequency divider 6b reducing the frequency of this oscillator 6a to a frequency usable by a logic circuit which controls 6c, by means of a control signal, a switching member 7, for example a transistor, for braking the generator 2 in order to regulate its frequency at a reference frequency advantageously corresponding to a correct indication of the time by the display members of the indication time 5.

The timepiece according to this document also comprises a device indicating the power reserve 9. This device comprises a counter 9a counting the successive braking signals 8 for a period of time determined by means of an additional frequency divider 9b . A memory 9c is connected at the output of the counter 9b so as to store the data counted during the determined period of time, at the output of which is connected a decoder 9d transforming the stored data into a control signal of the display means 9e. the power reserve comprising successive lines which illuminate or appear to the point corresponding to the value of the measured or calculated quantity, produced by means of either a colored strip or a liquid crystal cell.

The solution recommended in EP 0 762 243 nevertheless has the drawback of directly using the power of the generator to provide an indication of the power reserve, which has the effect of increasing the total power drawn from the generator, ie the power required to provide the hourly indication and the power required to provide the indication of the power reserve. Thus in most cases, the total power required represents an instantaneous power greater than the maximum capacity that the generator can provide, which can be detrimental, on the one hand, for the accuracy of the time indication and, d on the other hand, for the supply of the power reserve indication itself. And, at best, for cases where the indications provided remain correct, the autonomy of the timepiece is greatly reduced.

It is also known from the prior art, in particular from document EP 0 875 807 filed in the name of the present Applicant, a timepiece with a generator whose autonomy is higher. Such a timepiece, represented in FIG. 2, furthermore comprises common elements, bearing the same numerical references and already described with reference to FIG. 1, a storage device 10 intended to store and to restore energy. electric constituted by a part This storage device 10 connected to the terminals of the rectifier 4 comprises a conventional accumulator 10a.

When the barrel spring 1a is completely disarmed and the rotor 2a of the generator 2 does not rotate, the voltage Ug is obviously zero. If, in addition, the accumulator 10a of the storage device 10 is discharged, the voltage Ua is also zero, or in any case insufficient for the timepiece to operate. If the barrel spring 1 a is then raised, there comes a time when the rotor 2a begins to rotate, and where the Ug and Ua voltages start to increase.

The accumulator 10a is completely, or at least almost completely, discharged when the timepiece is stopped. When the rotor 2a begins to rotate and the voltage Ua reaches a sufficient value, the accumulator 10a begins to charge by absorbing a portion of the electrical energy supplied by the generator 2. This additional electrical energy is of course provided by the barrel spring 1a and comes from the conversion by the generator 2 of at least a portion of the mechanical energy of the spring.

If the engine torque supplied by the mainspring spring 1a becomes smaller than the maximum operating torque of the timepiece, the electrical energy produced by the generator 2 becomes insufficient to supply the various components of the regulator circuit 6 correctly. The accumulator 10a is then at least partially charged, so that the storage device 10 maintains the voltage Ua at a value such that the components of the regulator circuit 6 operate correctly. The electrical energy necessary for this operation is then provided, at least partially, by the accumulator 10a.

Thus, the autonomy of this timepiece, which comprises a storage device 10 capable of storing, in the form of electrical energy, a part of the mechanical energy contained in its mainspring, is increased by means of means which make it possible to use this electrical energy to operate the timepiece after the mainspring is no longer sufficiently armed.

However, a timepiece as described in document EP 0 875 807 only stores the excess of instantaneous power over that required to operate the timepiece correctly. Thus, the use of this excess of instantaneous power to provide an additional indication, such as the power reserve, would have the same drawbacks as those described in connection with the document EP 0 762 243, namely a direct use of the power from the generator, having the effect of greatly reducing the autonomy of the timepiece, which goes against the desired goal.

SUMMARY OF THE INVENTION

In order to overcome the disadvantages of the prior art, the idea according to the invention is to provide a reliable indication of the power reserve at the request of the user, without disturbing the normal operation of the timepiece, ie all ensuring a correct indication of the time.

In the context of the present invention, it has been demonstrated that the electromagnetic braking device of the generator allows, with full power reserve, that is to say with the spring of the fully armed barrel, to release a power relatively large average. The idea is therefore to modify the braking device so as to recover and store electrically the energy dissipated during the braking periods, within a reasonable period of time so as to be able to momentarily display additional information, such as, for example, the reserve of walk.

For this purpose, electrical energy storage means are provided for storing the energy dissipated during the braking periods of the generator as well as actuating means for activating, on request, means for indicating the power supply. power reserve of the timepiece thanks to the electrical energy stored previously. In this way, it does not reduce the autonomy of the timepiece and, moreover, the necessary accumulation means are simple, reliable and of reduced size, such as a capacitor of a value of the order of 10 microfarads.

For this purpose, the subject of the present invention is a timepiece with a generator whose characteristics are set forth in independent claims 1 and 10.

Advantageous embodiments of the present invention are the subject of the dependent claims.

The method of indicating the power reserve for such a timepiece will also be described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1, déjà décrite, représente une pièce d'horlogerie à génératrice avec indicateur de la réserve de marche selon un art antérieur ;
• la figure 2, déjà décrite, représente une pièce d'horlogerie à génératrice avec une autonomie prolongée selon un autre art antérieur ;
• la figure 3 représente une pièce d'horlogerie à génératrice avec indicateur de la réserve de marche selon un mode de réalisation préféré de l'invention ;
• les figures 4a-4c représentent des variantes de réalisation des moyens indicateurs de la réserve de marche ;
• la figure 5 représente un exemple d'un procédé mis en oeuvre pour l'indication de la réserve de marche.

Other features and advantages of the present invention will emerge more clearly on reading the following detailed description of embodiments of the invention given solely by way of nonlimiting example and illustrated by the appended drawings in which:

• FIG. 1, already described, represents a generator timepiece with a power reserve indicator according to a prior art;
• Figure 2, already described, shows a timepiece generator with extended autonomy according to another prior art;
• FIG. 3 shows a generator timepiece with power reserve indicator according to a preferred embodiment of the invention;
• Figures 4a-4c show alternative embodiments of the indicator means of the power reserve;
• FIG. 5 represents an example of a method implemented for the indication of the power reserve.

DESCRIPTION OF PREFERRED EMBODIMENTS

The invention proceeds, as already mentioned, from the general idea of accumulating the electrical energy dissipated during braking periods of the generator in order to have enough energy to indicate, on request, the power reserve. of a timepiece.

Indeed, it has been demonstrated in the context of the present invention that the energy dissipated during the braking periods of the generator represents an average instantaneous power of approximately one microwatt (ie a mean current microamper under about one volt ), insufficient to continuously supply a power reserve indicator. The idea is to be able to accumulate, within a reasonable period of time, for example a few minutes, sufficient energy to momentarily display the power reserve. An amount of energy between 40 and 80 microjoules is amply sufficient. This energy must also be released in a short time, ie we must have a much higher instantaneous power (up to a thousand times more) than the average braking power dissipated, depending on the type of indicator. the power reserve used.

We will now refer to Figure 3, which shows a simplified diagram of a timepiece according to a preferred embodiment of the invention. There are a number of elements common with those presented in the context of the prior art in FIGS. 1 and 2, elements which will not be repeated in detail here and whose numerical references remain unchanged.

Thus, there is a timepiece provided with a source of mechanical energy formed by a barrel 1 in which is housed a barrel spring 1a. The barrel is mechanically coupled, on the one hand, to the generator 2 whose output voltage Ug generated at the output is rectified through an active rectifier 4 and, on the other hand, to display means of a time indication 5, typically needles, through the workings 3 of the watch movement. The rotation speed of the needles is maintained at a constant average value by means of the control circuit 6, or regulator circuit, designed to slave the frequency of the generator 2 to a reference frequency, so that the speed of the hands corresponds to the speed required to obtain a correct indication of the time.

The timepiece further comprises electric energy storage means 11 arranged so as to accumulate the electrical energy dissipated during the braking periods of the generator 2, ie during short circuits applied to the generator by the switching means 7. The switching means 7 are activated by the regulator circuit 6 when the frequency of the generator is greater than the reference frequency, ie when the rotational speed of the rotor 2a is greater than the speed needles corresponding to a correct indication of the time.

Thus, the switching means 7 can occupy two positions, a first position 7a, in which the generator 2 is connected to the accumulation means 11 ensuring optimum impedance matching with the generator so as to draw maximum power instantly from the latter, which has the effect of braking and a second position 7b, in which the generator 2 is connected to the regulator circuit 6 for controlling the frequency of the generator with respect to a reference frequency corresponding to a correct indication of the 'hour.

The accumulation means 11 are preferably formed by a voltage booster 11a and a storage element 11b. The voltage booster 11a may be, for example, a Dickson type charge pump consisting of a plurality of stages arranged in cascade. Each stage of the pump comprises an active device, for example a diode or a diode-connected transistor, which conducts the current in one direction and a storage capacity. Note of course that other types of charge pump can be used. The accumulation element 11b may be a simple storage capacitor whose charge increases a little more with each braking. Given the efficiency of such a charge pump 11a, the accumulation element 11b, preferably a storage capacitor having a capacity of about 10 microfarads at 3 or 4 volts, can accumulate after a few minutes of braking, an energy of the order of 40 to 80 microjoules.

It will be noted for this purpose that once the accumulation element 11b loaded, the accumulation means 11 continue to ensure optimum matching of the impedance, and therefore the braking of the generator.

According to an alternative embodiment, the timepiece comprises an indicator, not shown here, arranged on the dial to indicate when the accumulation element 11b is sufficiently charged to power a power reserve indication device 12 This device for indicating the power reserve 12 comprises means for displaying the power reserve 12a and a control system 12b for these display means. The control system 12b has been shown here independently of the control circuit 6, but it will be noted that it could be integrated in the control circuit 6 as well.

The control system of the display of the power reserve is actuated (signal P) by actuating means 13 of the timepiece accessible externally, such as for example a push button called "request". The purpose of this control system is to provide an accurate indication of the power reserve (signal R) on the basis of a measurement (signal C) of the power reserve transmitted by the control circuit 6. The energy required for display of the power reserve is provided by the accumulation means (signal A).

Various methods can be implemented to measure the power reserve. A first method consists in providing the control system 12b with means for counting the successive braking operations over successive periods of time of a predetermined duration and for producing a display signal of the power reserve from the number of braking operations occurring at the during these successive periods of time.

A second method consists in providing the control system 12b with means for counting the number of times the generator is braked, means for measuring the duration of time between each braking and for producing a display signal for the power reserve. function of the result of the measurement of duration.

A third method consists in providing the control system 12b with means for transmitting, by electrical coupling between the generator 2 and electromechanical actuating means, a measurement of the average current dissipated during the braking periods, providing an indication of the power reserve to display means.

Several means of displaying the power reserve can be used according to the method chosen. Different examples of power reserve indication devices are shown in FIGS. 4a-4c. In these figures, the control system 12b has been integrated in the control circuit 6. There is therefore a control circuit 14 receiving the different signals A, C and P respectively supplying the electrical energy necessary for the display of the reserve of the power reserve indication and the request for such a power reserve indication.

FIG. 4a represents a first example using digital display means of the power reserve. Said display means are constituted by a display 15a LCD type (Liquid Crystal Display) arranged on the dial of the timepiece. The indication of the power reserve is preferably displayed as a percentage of the maximum power reserve, corresponding to the fully armed spring, or the remaining power reserve hours. These display means can be used with one of the first two methods described above.

It is preferably provided to leave the LCD display active for a period of time sufficient to allow the user time to read the power reserve indication after it has actuated the request push button.

FIG. 4b represents a second example using optical display means of the power reserve. Said display means consist of a high-performance light-emitting diode 15b visible through an opening on the dial of the timepiece. In this case, the control circuit 14 preferably delivers current pulses Ir, each of these pulses representing a percentage of the total power reserve, for example 20%. Thus, 5 pulses represent a 100% power reserve, ie a maximum power reserve. These display means can be used with one of the first two methods described above.

FIG. 4c represents a third example using electromechanical display means of the power reserve. Said display means are constituted by an analog display member, for example a needle 15c, moving relative to graduations representative of the power reserve, arranged in a window arranged on the dial of the timepiece. This analog display member 15c is driven a stepping motor 16, for example of bi-directional Lavet type, the latter being controlled by electrical coupling with the generator during the braking periods, according to the third method described above.

A first variant embodiment of this third example consists in providing an indication of the reserve by means of a Bidirectional Lavet motor (16) which makes it possible to automatically adapt the position of the analog display member (15c) when this is done. proves necessary (signal C) by means of a pulse (signal R), that is to say a step in one direction or the other depending on whether the power reserve decreases or increases, using the accumulated energy (signal A) by the accumulation means. It is important to note that according to this first embodiment, no intervention of the user of the watch is necessary for obtain an indication of the power reserve each time the power reserve varies by a predetermined amount, corresponding for example to a motor pitch. Advantageously, it is planned to be able to manually adjust (signal P) the position of the power reserve indicator, by means of a pusher, in order to correct any discrepancy between the position of the motor and that of the motor. indicator. Indeed, such an offset can occur in the event of impact occurring precisely while the motor is performing an adaptation of the position of the analog display member.

A second embodiment of this third example consists in providing a reset of the analog display member 15c during the actuation of the request push button. Thus, the signal P received by the control circuit 14 controls, in a first step, the reset of the display member and, in a second step, the indication of the power reserve. The display member then remains fixed in the position of indication of the power reserve until the next request by the user.

A third variant of this third example simply consists in adjusting the position of the display member to each request made by the user without prior reset.

1. 1.- accumuler de l'énergie électrique en chargeant les moyens d'accumulation avec la puissance dissipée lors des freinages successifs de la génératrice ;
2. 2.- requérir une indication de la réserve de marche en actionnant les moyens d'actionnement destinés à cet effet ;
3. 3.- mesurer selon l'une quelconque des méthodes sus-présentées l'indication de la réserve de marche ;
4. 4.- afficher l'indication mesurée avec les moyens d'affichage correspondants de la réserve de marche.

The method of indicating the power reserve for such a timepiece is described below. The method comprises a preliminary step of sufficiently cocking the barrel spring so that the timepiece can function properly. Apart from the first embodiment variant of the third example presented in FIG. 4c, the method then comprises the following steps:

1. 1. accumulating electrical energy by charging the accumulation means with the power dissipated during successive braking of the generator;
2. 2.- require an indication of the power reserve by operating the actuating means intended for this purpose;
3. 3.- measuring according to any one of the above-mentioned methods the indication of the power reserve;
4. 4.- Display the measured indication with the corresponding display means of the power reserve.

An intermediate step 1a (between steps 1 and 2) can be provided. This step 1a is to indicate when the accumulated energy level is sufficient to provide an indication of the power reserve.

• 2.- requérir automatiquement une indication de la réserve de marche.

The method of indicating the power reserve for the implementation of the first alternative embodiment of the third example shown in FIG. 4c, step 2 concerning the request made by means of the actuating means is replaced by a step of:

• 2.- automatically require an indication of the power reserve.

It will be understood that various modifications and / or improvements obvious to those skilled in the art can be made to the various embodiments of the invention described in the present description without departing from the scope of the invention defined by the appended claims. In particular, the present invention is not limited solely to the methods of measuring the power reserve described above as well as to the various examples of power reserve display means mentioned.

It will also be noted that other accumulation means may be used to store the electrical energy dissipated during braking periods of the generator. Regarding the actuating means, it is possible to use as an alternative, a shock detector at the ice of the timepiece, or a crown rod.

It will also be noted that it is possible to increase the autonomy of the timepiece according to the invention by providing an additional storage device such as that described in document EP 0 875 807, this additional device being loaded by means of the additional electrical energy compared to the energy required for proper operation, when the generator is not braked.

Claims (14)

1. Timepiece including a mechanical power source (1) coupled, on the one hand, to first time related information display means (5) and, on the other hand, to a generator (2), a regulator circuit (6 ; 14) arranged for enslaving the generator frequency to a reference frequency, said regulator circuit including switching means (7) arranged for electrically braking the generator when the generator frequency is higher than the reference frequency, and second power-reserve display means (12a; 15a, 15b) controlled by means for measuring the power-reserve (12b ; 14), said timepiece being characterized in that it further includes means (11) for accumulating the electrical energy dissipated during generator braking periods and means (13) for actuating said second display means arranged for displaying the power-reserve by means of the electrical energy accumulated by said accumulation means (11).
2. Timepiece according to claim 1, characterized in that said electrical energy accumulation means (11) are formed by a voltage step-up circuit (11a) electrically connected to the generator (2) during braking periods and controlled by the regulator circuit (6) so as to accumulate the energy dissipated during said periods in a storage capacitor (11b).
3. Timepiece according to claim 1 or 2, characterized in that the actuating means (13) are a control member accessible from outside the timepiece.
4. Timepiece according to any of claims 1 to 3, characterized in that the power-reserve measuring means (12b; 14) include means for fixing successive time periods of a predetermined length, means for counting, during each of said fixed periods, the number of times that the generator is braked by the switching means and means controlled by the actuating means to provide, as a function of the result of counting, power-reserve information to the second display means (15a; 15b).
5. Timepiece according to any of claims 1 to 3, characterized in that the power-reserve measuring means (12b; 14) include means for counting the number of times that the generator is braked by the switching means, means for measuring the period of time between each braking and means controlled by the actuating means, for providing, as a function of the result of the period of time measurement, power-reserve information to the second display means (15a ; 15b).
6. Timepiece according to claim 4 or 5, characterized in that the second display means are optical means formed by a light emitting diode with a high yield (15b) supplying a visual power reserve indication by means of light pulses.
7. Timepiece according to claim 4 or 5, characterized in that the second display means are digital means formed by a liquid crystal display (15a).
8. Timepiece according to any of claims 1 to 3, wherein the generator (2) includes at lest one coil (2b) and characterized in that the power-reserve measuring means (12b) include an additional coil electrically coupled to said at least one coil of the generator during braking periods by the switching means (7) and an electrically controlled motor (16) controlled by said actuating means (13), for providing, as a function of an electrical quantity transmitted during the electrical coupling, power-reserve information to the second display means (15c).
9. Timepiece according to claim 8, characterized in that the second display means are electromechanical means formed by an analogue member (15c) driven by said electrically controlled motor (16).
10. Timepiece including a mechanical energy source (1) coupled, on the one hand, to first time information display means (5) and, on the other hand, to a generator (2), a regulator circuit (6; 14) arranged for enslaving the generator frequency to a reference frequency, said regulator circuit including switching means (7) arranged for electrically braking the generator when the generator frequency is higher than the reference frequency, and second power-reserve display means (12a; 15c) controlled by power-reserve measuring means (12b ; 14, 16), said timepiece being characterized in that it further includes means for accumulating (11) the electrical energy dissipated during the generator braking periods, and in that said power-reserve measuring means automatically are arranged for adapting the position of said second display means to display the power-reserve by means of the electrical energy accumulated by said accumulation means.
11. Timepiece according to claim 10, wherein the generator (2) includes at least one coil (2b) and characterized in that the power-reserve measuring means (14, 16) include an additional coil electrically coupled to said at least one coil of the generator during braking periods by the switching means (7) and an electrically controlled motor (16) controlled by said regulator circuit (14), to provide, as a function of an electrical quantity transmitted during electrical coupling, power-reserve information to the second display means (15c).
12. Timepiece according to claim 11, characterized in that the second display means are electromechanical means formed by an analogue member (15c) driven by said electrically controlled motor (16).
13. Timepiece according to any of claims 10 to 12, characterized in that it further includes adjustment means for manually adjusting the position of said analogue display means.
14. Timepiece according to any of the preceding claims, characterized in that indicator means are provided for indicating when the energy stored by the accumulation means is sufficient to display the power-reserve.

Images