EP0762243A1 - Timepiece with power-reserve indication - Google Patents

Abstract

The watch movement includes a barrel (1) and a spring (1a) and hands (5), with an electrical energy generator (2) providing via a rectifier (4) a direct voltage to a regulator circuit (6). The regulator circuit controls the speed of the generator in order to provide the correct speed of rotation of the hands to display the current time. The regulator circuit includes a transistor (10) for short-circuiting the generator and braking it when the regulator circuit determines that the hands are moving too fast to display the correct time. Circuitry is provided to count the number of times the generator is braked during a given period of time, and as a result of this count provide a visual indication of the reserve of energy held. This may be displayed in the form of a sliding scale display, or the illumination of one of several different markers showing the hours operation remaining.

Description

The present invention relates to a power reserve indication device for an electronic timepiece.

More particularly, the invention relates to such a device for an electronic timepiece in which the electrical energy is generated by a generator driven by a spring barrel.

Mechanical watches have been known for a long time, provided with a device for indicating the power reserve generally operating in a differential manner and coupled both to the winding device and to the barrel which houses the spring of the watch, source of the walking energy of it. The indicator member of such a device is then driven in one direction when the barrel is reassembled and in the other while the spring relaxes and advances the watch.

Such a power reserve indication device could be used in a timepiece of the electronic type comprising an electric power generator coupled to the spring barrel and intended to power an electronic timepiece circuit regulated by an oscillator with quartz.

However, in such an application, due to the presence of electronic means, the conventional mechanism for indicating the reserve may appear complex and bulky, while the electronic circuit makes it possible to considerably simplify the indication of the power reserve.

The object of the invention is to propose a simple and effective solution in this context for indicating in an irreproachable and clear manner the power reserve of an electronic timepiece which derives its electrical energy from a generator driven by a spring. of barrel, this generator also serving to regulate the progress of the part.

The invention therefore relates to a timepiece comprising a barrel, a spring housed in this barrel, time display members mechanically coupled to said barrel, a generator of electrical energy also mechanically coupled to said barrel and intended for delivering an alternating voltage, a rectifier connected to said generator for delivering a direct voltage from said alternating voltage, and a regulator circuit supplied by said direct voltage and intended to control the speed of said generator so as to impose on said organs of display of a speed of rotation corresponding to an accurate indication of the current time, said regulator circuit comprising for this purpose a switching member capable of short-circuiting said generator and of braking it when said regulator circuit finds that said generator is rotating at a speed greater than that to which it must turn for ace provide a correct indication of the time, said timepiece being characterized in that it also comprises a device for indicating the power reserve comprising means for fixing successive periods of time of predetermined duration, means for, at during each of said periods, count the number of times that said generator is braked by said switching member and means for, depending on the result of said counting, provide a visual indication of the power reserve.

• la figure 1 montre un schéma général simplifié d'une pièce d'horlogerie selon l'invention;
• la figure 2 est un diagramme des temps illustrant le fonctionnement de la pièce d'horlogerie selon l'invention;
• les figures 3a à 3f montrent plusieurs variantes de dispositifs d'affichage pouvant être utilisés dans la pièce d'horlogerie selon l'invention.

Other characteristics and advantages of the invention will appear during the description which follows, given solely by way of example and made with reference to the appended drawings in which:

• Figure 1 shows a simplified general diagram of a timepiece according to the invention;
• Figure 2 is a timing diagram illustrating the operation of the timepiece according to the invention;
• Figures 3a to 3f show several variants of display devices that can be used in the timepiece according to the invention.

We will first refer to Figure 1 which shows a simplified general diagram of a timepiece according to the invention. It should be noted that the part of this diagram relating to the regulator circuit intended to control the speed of rotation of the generator of this timepiece, will not be described in detail here, the skilled person can easily build this device control by referring to the description of Swiss patent application No 686 332 in the name of the Applicant of this patent application. However, to make it easier to understand the present invention, the essential elements of the diagram and of the operation of this regulator circuit will be briefly recalled here.

The timepiece equipped with a power reserve indication device according to the invention comprises a source of mechanical energy formed by a barrel 1 housing a spring 1a of the usual type in watchmaking technique, with manual winding or automatic.

The barrel 1 is mechanically coupled to the rotor 2a of an electric generator 2 via a gear train 3 symbolized by dashed lines.

The generator 2 comprises a coil 2b at the terminals B1 and B2 from which an alternating voltage Ug is generated, when the rotor 2a is rotated, this rotor carrying a permanent magnet generating a magnetic field symbolized by an arrow in the figure 1 and with which the coil 2b is coupled.

The terminals B1 and B2 of the coil 2b are connected to a rectifier 4, the output terminals 4a and 4b supply a continuous voltage Ua derived from the alternating voltage Ug and intended to supply the various electronic circuits of the timepiece.

Hands 5 or any other conventional mechanical time display means are coupled to the gear train 3 in order to allow the display of the current time and possibly the date and the day and other time indications. .

The speed of rotation of the hands 5 is maintained at a constant average value thanks to a regulator circuit 6 which controls this value at a set speed Vc.

As described in the aforementioned patent application, the components of the regulator circuit 6 are designed to regulate the speed of rotation of the rotor 2a, so that the hands 5 rotate at the required speed of just indicating the time when the rotor rotates at the set speed Vc. This is four turns per second, for example.

The servo circuit 6 includes an oscillator 7 stabilized by a watchmaking type quartz and a frequency divider 8 reducing the frequency of this oscillator to a value usable by a functional block 9 which controls the gate of a semiconductor component 10 , for example an n type MOS transistor.

The latter is connected by its main circuit to the terminals B1 and B2 of the coil 2b of the generator 2. Consequently, this semiconductor component when it is made conductive, makes it possible to short-circuit this coil and thus to have a braking effect on the generator's rotational movement 2.

• a) la vitesse moyenne de rotation du rotor 2a soit supérieure à la vitesse de consigne Vc, tant que le ressort de barillet 1a n'est pas presque complètement désarmé, à condition que la bobine 2b ne soit pas court-circuitée par le composant semi-conducteur 10, et que
• b) cette vitesse moyenne de rotation soit inférieure à la vitesse de consigne Vc, Si la bobine 2a est court-circuitée et ce même lorsque le ressort de barillet 1a est complètement remonté et que le couple moteur qu'il fournit, a une valeur maximale.

The constructive characteristics as well as the functionalities of the various elements which have just been described are designed in such a way that

• a) the average speed of rotation of the rotor 2a is greater than the set speed Vc, as long as the barrel spring 1a is not almost completely disarmed, provided that the coil 2b is not short-circuited by the semiconductor component 10, and that
• b) this average speed of rotation is less than the set speed Vc, if the coil 2a is short-circuited even when the barrel spring 1a is completely wound up and the motor torque which it supplies has a maximum value .

Note also that in the context of the present invention, the elements and functionalities briefly listed above could possibly be achieved in other ways than that described in the aforementioned patent application, provided that the speed of rotation of the generator is properly regulated as indicated above. This regulation must therefore be made as a function of the setpoint speed Vc required (determined by the correct indication of the time by the hands 5) by means of successive brakes of the generator 2 due to short-circuits repeated from coil 2b thereof.

The brake control signal SF which flows on a line 11 between the functional block 9 and the grid of the semiconductor component 10 is of the logic type and in the example shown, it is assumed that this signal is in the logic state " 0 "as long as the timepiece delays, that is to say as long as the average speed of the rotor 2a is lower than the set speed Vc. Under these conditions, the component or transistor 10 remains blocked and the rotor 2a is not braked.

On the other hand, as long as the timepiece advances or the average speed of the rotor 2a is greater than the set speed Vc, the braking control signal SF is formed by pulses of determined durations starting at the start of each half cycle, for example positive, of the voltage Ug at the terminals B1 and B2 of the coil 2b. During each of these pulses of the control signal SF, the latter is in state "1" making the transistor 10 conductive and braking the rotor 2a.

The information concerning the alternating voltage Ug delivered on the terminals B1 and B2 of the coil 2b reaches the functional block 9 via a line 12.

The invention is based on the observation that the braking signal SF circulating on the conductor 11, in other words the frequency with which the rotor 2a is braked, constitutes a measurement of the state of winding of the spring 1. In fact, when the barrel spring is completely wound up, that is to say that the power reserve is maximum, the engine torque it produces is maximum. Under these conditions, the rotor will constantly tend to rotate at a speed greater than the set speed Vc and it must therefore be braked at the start of each period of the voltage Ug.

As the barrel spring 1a relaxes, the engine torque which it supplies decreases progressively, so that the rotor must less and less frequently be braked and that gradually its speed will be less and less frequently higher at the set speed Vc, until it is no longer braked at all. This will then mark the exhaustion of the power reserve and the timepiece ends up stopping if the user does not wind the spring 1a.

According to the invention, the power reserve indication device thus comprises means which account for successive braking operations over successive periods of time of predetermined duration and which generate a display signal from the number of braking operations occurring during of these successive time periods. An exemplary embodiment of these means will now be described in more detail.

The connection 11 of the functional block 9 which transmits the brake control signal SF to the transistor 10 is connected to a counter 13 responsible for counting the number of this signal. Its counting input C is therefore connected to connection 11. Its reset input R is connected to the output Q of a frequency divider 14 which fixes successive periods of time of predetermined duration. In this case, the input of this divider 14 is connected to the output of the frequency divider 8 so as to further divide the output frequency of the latter.

A memory 15 formed for example by a conventional flip-flop locking circuit, is connected by its inputs E1 to E4 respectively to certain outputs, here the outputs Q9 to Q12, of the counter 13. The clock input C of this memory is connected to the output Q of the frequency divider 14. The outputs Q1 to Q4 of the memory 15 are respectively connected to the inputs E1 to E4 of a decoder 16 whose outputs, here S1 to S9, are respectively connected in turn to the inputs E1 to E9 display means or a display 17.

In the example under consideration which is in no way limiting, the output signal from the frequency divider 8 has a period of 250 ms. The rate of division of the frequency divider 14 is 2048, which makes appear at its output a pulse every 512 seconds (see figure 2). This signal thus determines the predetermined period of time during which there are the times that the transistor 10 puts the coil 2b in short circuit.

Assuming that the rotor 2a turns too fast relative to the set speed Vc for the entire duration of the counting period and is braked at the start of each period of the voltage Ug (this means that the spring is only 'at the start of its expansion), the number of pulses of the control signal SF is greater than 2048. As a result, the counter 13 must have a higher capacity and include one more flip-flop which gives it a minimum capacity necessary for 4096.

• La courbe a) montre le signal de sortie du diviseur de fréquence 14. Ce signal présente une période de durée D, choisie ici comme étant égale à 512 secondes.
• La courbe b) montre le signal SF appliqué à l'entrée de comptage du compteur 13, étant entendu que la figure montre, à titre illustratif, deux périodes de comptage relativement espacées pendant lesquelles les nombres d'impulsions sont assez différents l'un de l'autre. Elles rendent donc compte de deux phases de fonctionnement pendant lesquels l'armage du ressort est fort, respectivement faible.
• La courbe c) représente le contenu du compteur 13 respectivement pendant les deux périodes représentées, tandis que la courbe d) montre la sortie de la mémoire 15 qui conserve chaque fois l'information de la période de comptage précédente et qui est remis à zéro à chaque expiration de la période de comptage grâce à un signal de remise à zéro qui transite sur un conducteur 18 (figure 1).

FIG. 2 illustrates by a diagram representing some significant signals as a function of time, how the device for indicating the power reserve that has just been described works.

• Curve a) shows the output signal of the frequency divider 14. This signal has a period of duration D, chosen here as being equal to 512 seconds.
• Curve b) shows the signal SF applied to the counting input of counter 13, it being understood that the figure shows, by way of illustration, two relatively spaced counting periods during which the numbers of pulses are quite different, one of the other. They therefore account for two operating phases during which the winding of the spring is strong, respectively weak.
• The curve c) represents the content of the counter 13 respectively during the two periods represented, while the curve d) shows the output of the memory 15 which keeps each time the information of the previous counting period and which is reset to zero at each expiration of the counting period by means of a reset signal which passes over a conductor 18 (FIG. 1).

FIG. 3 shows some examples of practical embodiment of the display means 17. The figure represents in a), b), c) and d) displays indicating the instantaneous value of the output of the memory 15 respectively by an ungraduated indication (a)) or graduated in 12 hour intervals for example (b), c), and d)). Of course, the ways of producing these display means are multiple and those skilled in the art will be able to easily design them. For example, the dial C of the timepiece may include a window G behind which a colored band moves which is animated by a small actuator (not shown) receiving its signal control of the decoder 16. As a variant, it is possible to use a series of light-emitting diodes.

In e) and f) of FIG. 3, two other variants are shown respectively, one comprising a liquid crystal display CL displaying the power reserve in hours, and the other comprising several openings O forming a graduated scale in 12 hour periods for example. A light-emitting diode can be provided behind each of these openings, being suitably controlled by the outputs of the decoder 16.

The resolution of the display 17 can be arbitrary, for example by periods of a determined number of hours, as represented in b), c), d) and f) of FIG. 3, by units of hours as in e), or by all or nothing with a single indicator, a variant which has not been shown in the drawings. Those skilled in the art will be able to adapt the memory 15, the decoder 16 and the display 17 to these different display possibilities which all come within the scope of the invention.

In particular, it is clear that an increase in resolution goes hand in hand with an increase in the capacity of the memory 15.

However, as has already been explained above, it is possible to make the elements and functionalities in another way than that described in the aforementioned Swiss patent application No. 686 332. Thus, it is understood that in analogy it is also possible, while remaining within the scope of the present invention, to measure the duration between each occurrence of a braking pulse SC to determine the power reserve instead of counting this number of pulses for a predetermined fixed duration, as explained above. In this case, the power reserve is large If the duration between two successive pulses is short, that is to say when you have to brake often, and the reserve is low if this duration is long.

It is also possible that the memory 15 stores only a certain number of most significant bits of the output information of the counter 13, for example the four most significant bits, as shown in FIG. 1. In these conditions, we can theoretically. display 16 separate pieces of information on display 17. This is generally considered to be redundant for the intended purpose, a number of pieces of information of a maximum of nine should be sufficient to properly inform the user of the timepiece about his power reserve.

It should be noted in passing that the device according to the invention can, to a certain extent, inform the user about the mechanical state of the timepiece. For example, if the display 17 does not reach the maximum reserve graduation, when the user has just completely wound the spring, this will mean for example that the timepiece needs a revision and requires a new one. lubrication.

Claims (7)

Timepiece comprising a barrel (1), a spring (1a) housed in this barrel (1), time display members (5) mechanically coupled to said barrel (1), an electric power generator (2) also mechanically coupled to said barrel (1) and intended to deliver an alternating voltage (Ug), a rectifier (4) connected to said generator (2) to deliver a direct voltage (Ua) from said alternating voltage (Ug ), and a regulator circuit (6) supplied by said direct voltage (Ua) and intended to control the speed of said generator so as to impose on said display members (5) a speed of rotation corresponding to a fair indication of the current time, said regulator circuit (6) comprising for this purpose a switching member (10) capable of short-circuiting said generator (2) and of braking it when said regulator circuit (6) finds that said generator (2) is rotating higher speed ior to that (Vc) at which it must turn to ensure correct indication of the time, said timepiece being characterized in that it also comprises a power reserve indicator device comprising means (8, 14 ) to fix successive periods of time of predetermined duration (D), means (13) for, during each of said periods, counting the number of times that said generator (2) is braked by said switching member (10), and display means (17) for, depending on the result of said counting, providing a visual indication of the power reserve. Timepiece according to claim 1, wherein said regulator circuit (6) comprises a clock quartz oscillator (7) and a first frequency divider (8), characterized in that said means for fixing said time periods of duration (D) predetermined include an additional frequency divider (14) connected to the output of said first divider (8). Timepiece according to any one of claims 1 and 2, wherein said generator comprises a coil (2b) and said switching member (10) is a semiconductor component connected by its main circuit to the terminals of said coil ( 2b) of said generator (2) so as to be able to short-circuit it under the control of said regulation circuit (6) characterized in that said means for counting comprises a counter (13) connected to the control grid of said component (10 ) to count the number of times that it short-circuits said coil (2b) during said predetermined time (D). Timepiece according to claim 3, characterized in that said counter (13) is connected to a memory circuit (15) which stores the state of said counter during each of said predetermined periods. Timepiece according to any one of claims 1 to 4, characterized in that said display means (17) are arranged to provide an indication graduated in hours or multiples of hours on the dial (C) of said piece . Timepiece comprising a barrel (1), a spring (1a) housed in this barrel (1), time display members (5) mechanically coupled to said barrel (1), an electric power generator (2) also mechanically coupled to said barrel (1) and intended to deliver an alternating voltage (Ug), a rectifier (4) connected to said generator (2) to deliver a direct voltage (Ua) from said alternating voltage (Ug ), and a regulator circuit (6) supplied by said direct voltage (Ua) and intended to control the speed of said generator so as to impose on said display members (5) a speed of rotation corresponding to a fair indication of the current time, said regulator circuit (6) comprising for this purpose a switching member (10) capable of short-circuiting said generator (2) and of braking it when said regulator circuit (6) notes that said generator (2) rotates at a speed greater than that (Vc) at which it must rotate to ensure correct indication of the time, said timepiece being characterized in that it also comprises a device for indicating the power reserve comprising means (13) for counting the number of times that said generator (2) is braked by said switching member (10), means (8, 14) for measuring the duration of time between each braking and display means (17) for, depending on the result of said duration measurement, providing a visual indication of the power reserve. Timepiece according to claim 6, characterized in that said display means (17) are arranged to provide an indication graduated in hours or multiples of hours on the dial (C) of said piece.

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