EP1346264A1

EP1346264A1 - Analog electronic watch having a time reset device following power shortage

Info

Publication number: EP1346264A1
Application number: EP01985360A
Authority: EP
Inventors: Jean-Claude Martin; Jean-Charles Guanter
Original assignee: Asulab AG
Current assignee: Asulab AG
Priority date: 2000-12-18
Filing date: 2001-11-29
Publication date: 2003-09-24
Anticipated expiration: 2021-11-29
Also published as: DE60129738D1; EP1346264B1; US20040027925A1; JP2004516482A; EP1215545A1; JP4554884B2; DE60129738T2; US6934223B2; KR100880347B1; CN1222850C; CN1481520A; WO2002050617A1; KR20030059313A

Abstract

The invention concerns an electronic watch comprising analog display means (1) consisting of at least a hand (2) driven by at least a motor (3), a time base (4) for controlling the means powering (8) the motor, a rechargeable power source (9), and means for stopping (14) the motor, which act in particular on the powering means and time counting means (18) synchronously with the display means for adequate power supply. When a power shortage is detected by the stop means, the display means are stopped, the corresponding value of the counting means is stored in storage means and the counting means continue to operate. When sufficient power is restored, means computing time difference (20) send signals representing the time difference (21) between the stored value and the value of the time counting means to the powering means for time reset of the analog display means.

Description

ANALOGUE ELECTRONIC WATCH HAVING A TIME-SETTING PROVISION F FOLLOWING A POWER SUPPLY

The present invention relates to an electronic watch which comprises analog display means constituted by at least one hand driven by at least one motor, a time base for controlling means for driving said motor, a rechargeable power source, engine stop means acting in particular on said drive means and time counting means in synchronism with said analog display means for a sufficient supply voltage of the source.

A watch comprising means for detecting insufficient supply of the engine is known in particular from document WO 98/33098. This document presents an electronic watch comprising hands driven by a motor and controlled by electronic means containing time data, a power source and means for detecting the insufficiency of this source. In the event of insufficient supply, the needles are brought and maintained in reference positions programmed in advance in the electronic means.

This watch nevertheless has some drawbacks. In fact, the hands of the watch reflect the value of a counter for electronic means. This is why it is necessary to bring the hands to a reference position, during a supply failure, to force the value of this counter to a reference value programmed before starting the watch. Thus, this counter synchronized with the hands is no longer usable as a time counter. It is therefore necessary to have a second counter that counts the time during a power supply failure. On the other hand, during normal operation of the watch, which represents the majority of the operating time, the two counters contain the same values. These two counters unnecessarily complicate the electronic means of the watch.

The main object of the invention is therefore to overcome the drawbacks of the aforementioned prior art by providing an electronic watch which comprises simplified electronic means which do not require programming a reference value for setting the time due to insufficient time. 'food.

To this end, the subject of the invention is an electronic watch of the type mentioned in the introduction which is characterized in that upon detection of an insufficient supply by said stop means, said display means are stopped and the corresponding value of said counting means is stored in means of storage, said counting means continuing to operate, and in that time difference calculating means send, as soon as the supply is again sufficient, time difference signals between the stored value and the value of the means of counting to said drive means for resetting said analog display means to the time.

Advantageously, said engine stop means are actuated for a first threshold voltage corresponding to the detection of an insufficient supply of the engine and they are kept actuated as long as a second threshold voltage greater than the first threshold voltage has not been reached by the power source, which makes it possible to avoid the problems linked to the variation in supply voltage due to the variations in load when elements such as the motor are stopped.

This second threshold voltage corresponds to a determined charge level of the power source. In fact, when one of the energy-consuming elements such as the motor stops, it is common for rechargeable power sources of the battery or accumulator type to have their voltage level which varies somewhat. This variation in the supply voltage is a phenomenon known to those skilled in the art. When the load of the power source becomes insufficient to supply the current necessary for the operation of the watch, the stopping of an energy-consuming element, such as the motor, causes a large drop in load and current requirements, which causes a variation in the supply voltage. This discontinuity in the discharge of the power source creates, as shown in Figure 3, a transient period (t1, t1 + dt), during which the motor is stopped and restarted several times in succession until the voltage level is insufficient to start the motor again. This transitional period prematurely wears out the parts of the watch which are thus activated and then stopped. In addition, the user can think of a malfunction of his watch by seeing the hands stop, place himself in a reference position and start several times in succession. According to a variant of the invention, it is possible, upon detection of an insufficient supply, to provide a sufficient period of time for maintaining the activated stop means to avoid the effects of the variation of the load of the power source between t1 and t1 + dt described above.

The storage means may include in particular a non-volatile memory. Other characteristics and advantages of the present invention will appear in the following description, given by way of example and made with reference to the appended drawings, in which:

- Figure 1 shows an overview of the time setting device according to a preferred embodiment of the invention;

- Figure 2 shows the state of the motor as a function of the voltage delivered by the power source;

- Figure 3 shows a period of discharge / recharge of the power source in a device of the prior art, and - Figure 4 shows a period of discharge / recharge of the power source in a device according to invention.

Figure 1 shows the elements of the watch necessary for understanding the invention. The electronic watch comprises analog display means 1 generally consisting of at least two hands 2. One is used to indicate the hours and the other the minutes. It is possible to provide a third hand used to indicate, for example, the seconds.

The hands 2 are driven by at least one motor 3. Preferably, the hour hand and the minute hand are driven by a stepping motor and the second hand is driven by another stepping motor. Indeed, for the sake of energy saving, the motor driving the second hand can be stopped earlier.

The arrangement of the motors and cogs for driving the hands will not be described here. In fact, there are already known clock movements comprising several motors for actuating the hands, for example, individually.

A time base 4 makes it possible to define for each motor 3 the pitch for the advance of the needle 2 associated with said motor. The time base 4, generally used, consists in particular of a quartz oscillator, referenced 5 and 6, and of different frequency dividing stages 7 of the oscillator 6 to drive each motor 3 with the desired pitch. Drive means 8 of the motor or motors 3 are provided for this purpose.

The motor 3 is supplied by a rechargeable power source 9 of the accumulator or battery type. This power source 9 can be recharged in different ways, in particular by the use of photovoltaic cells, of oscillating mass, or even by electrical contacts. The latter method will preferably be used to satisfy a need for rapid and complete recharging. Voltage comparators 11 and 12 are placed at the output of the power source 9. They receive as input a fraction of the supply voltage obtained by a voltage divider, for example a resistive bridge, and a voltage V ′ _S ι , respectively V ' _S2 . These voltages reflect the threshold voltages V _S ι and V _S2 (see Figures 2 to 4).

V _S ι corresponds to a sufficient voltage to ensure synchronization between the time indication of the analog display 1 and the pulses supplied by the time base 4 to the motor drive means 8. Typically, the value of this voltage is chosen with a safety factor in relation to the minimum voltage necessary for the correct operation of the motor 3.

V _S2 corresponds to a determined load level for which the load is considered sufficient to restart the engine. The latter could still function correctly below this voltage. This second threshold voltage also makes it possible to avoid the effects as discussed with reference to FIG. 3. Obtaining the reflective voltages V ′ _S1 and V ′ _S2 is carried out by means of a conventional circuit known to those skilled in the art. . This circuit, not shown, comprises means for supplying a reference voltage to which a resistive voltage divider bridge is applied, defining the two voltages V ' _S ι and V' _S2 . These two voltages are therefore lower than the threshold voltages V _S ι and V _S2 . The comparator 11, respectively 12, compares the fractionated supply voltage with the reflection voltage V ' _S ι, respectively V' _S2 . These comparison means 11 and 12 are operational as long as the supply voltage is greater than a minimum voltage V ₀ uτ (see FIG. 4).

Advantageously, there is provided switching means, not shown, leaving only the comparator 11 active when the power source 9 is discharged, and conversely leaving the comparator 12 active when the power source 9 is charged.

Engine stop means 14 recover the results of the comparisons. These means make it possible in particular to detect an insufficient supply of the source 9. According to the state of the supply and according to the previous state of the motor supplied by a signal 13, these stop means 14 will send to the means of drive 8 a signal 15 for controlling the state of the motor, which will either be a signal to stop the motor or a signal to start the motor. The evolution of these engine states as a function of the comparisons made by the comparators 11 and 12 will be studied in detail in FIG. 2.

The engine stop means are in particular connected to a time reset circuit 17. This time reset circuit 17 is composed of at least one counter 18 making it possible to count the time according to the pulses received by the time base 4, storage means composed of at least one memory 19 making it possible to store the content of the counter 18 and means of calculating time difference 20 allowing d '' obtain the offset 24 between the position of hands 2 and the exact time.

The counter 18 operates continuously as long as the power source 9 delivers a minimum voltage V ₀ uτ sufficient to supply the time base 4 and operate said counter 18. Below this voltage V ₀ uτ, no more functions exist. is guaranteed to function properly. In general, this voltage V ₀ uτ is much lower than the first threshold voltage V _S ι, which leaves the user sufficient time, for example, a minimum of several hours, to realize the insufficiency feed, needles 2 being stopped. The user can then recharge the accumulator or the battery 9 while keeping exact time information. In the event of a power supply failure, the motor 3 is stopped as well as the hands 2. The stop means 14 then send the information signal 16a concerning the stopping of the motor to a memory 19. The value then contained in the counter 18 is stored in the memory 19. Preferably, a non-volatile memory 19 is used. When the motor 3 is restarted, an information signal 16b is sent to the difference calculation means 20. Thus, these means 20 perform the subtraction between the current value 22 of the counter 18 and the value stored 23 in the memory 19 The result obtained is in the form of time difference signals 21 which are sent to the drive means of the motor 8 in order to reset the hands 2 to the time. Hands 2 are brought to the hour by the shortest route. Depending on the value of the difference, the drive means 8 control the rotation of the motor 3 in one direction or the other.

An example of implementation could be as follows:

1. 0 hours <(current time - memorized time) <6 hours rotation: clockwise;

2. 6 hours <(current time - memorized time) <12 hours rotation: anticlockwise;

3. -12 hours <(current time - memorized time) <-6 hours rotation: clockwise; 4. -6 hours <(current time - memorized time) <0 rotation hour: anticlockwise; Other embodiments making it possible to bring the hands to the hour by the shortest route can also be envisaged.

FIG. 2 represents the operation of the engine stop means 14 as a function of the comparisons made by the comparators 11 and 12 and as a function of the state of the engine 15, seen in FIG. 1.

The abscissa shows the supply voltage delivered by the source 9. This voltage can vary between 0 and V _MAX - The zero voltage corresponds to the voltage delivered when the battery or accumulator 9 is completely discharged. The voltage V _A X corresponds to the maximum voltage delivered when the battery or the accumulator is fully charged. The voltage V ₀ uτ, defined earlier, corresponds to the minimum voltage for which the data of the counter 18 is exact. The voltages V _S ι and V _S2 correspond to the two threshold voltages whose associated reflection voltages V ′ _S ι and V's ₂ make it possible to control the state of the motor.

On the ordinate, the state in which the engine is located is shown. If the state corresponds to A, the engine is stopped. If the state corresponds to M, the engine is running.

Starting from a maximum state of charge of the power source 9, the voltage delivered is V _MAX - At this power voltage, the energy supplied is sufficient, the motor is therefore running, that is to say - say in state M. With time and the use of the time functions of the watch, the battery or accumulator 9 is discharged. When the supply voltage becomes lower than the threshold voltage V _S ι, the energy supplied by the source is no longer sufficient to ensure synchronization between the time base 4 and the hourly indication of the hands 2. The means engine 14 are actuated and the engine 3 is stopped by the motor drive means 8. The engine 3 goes to state A. Once the engine 3 stopped, the needles 2 are also judgment. The value of the time counter 18 is memorized, the counter continuing to operate. The majority of the energy consumed by the device is the energy consumed by the motor. This last stopped, consumption becomes very low. This is why, the watch can still calculate the time during the whole period of time during which the supply voltage is less than V _S ι but greater than V ₀ uτ- The user seeing the hands 2 stopped then knows that the battery or accumulator 9 must be recharged. When recharging the power source 9, the motor 3 is only restarted from a second threshold voltage V _S2 greater than V _S ι and corresponding to a determined minimum recharging level. The stop means 14 remain actuated, during recharging, for a value between V _S1 and V _S2 , because the state of the engine is at A. Figures 3 and 4 show a conventional discharge / recharge cycle of the power source 9 as a function of time, according to the prior art (Figure 3) and according to the invention (Figure 4).

As has been described in the introduction to this description, a device, according to FIG. 3, leads to the creation of a transitional period which we want to avoid.

Indeed, during the discharge, when the supply voltage becomes lower than the threshold voltage V _S ι, at t1, the motor is stopped. However, the motor is the majority energy consumer of the device. This is why, when stopped, the battery charge drops sharply. The supply voltage again becomes greater than V _S ι. At the same time, the result of the comparator 11 between the fraction of the supply voltage and the associated reflection voltage V ' _S ι, controlling not only the stopping, but also the running of the motor, becomes positive again, thus, the engine is restarted directly after it has been stopped. There is then a transitional period during which the engine and therefore the needles are stopped and then restarted several times in succession. This period ends, at t1 + dt, when the overvoltage is no longer sufficient to restart the engine.

In a device according to the invention, as in FIG. 4, two reflective voltages V ′ _S ι and V ′ _{S2 are used} associated with the threshold voltages V _S ι and V _S2 to manage the means for stopping the motor 14 which avoids the aforementioned drawback, current in the devices of the prior art provided with battery or accumulator 9. For this, a second threshold voltage V _S2 greater than V _S ι is provided. The value of V _S2 is taken in such a way that it is greater than the voltage V _S ι to which the overvoltage due to the stopping of the main consumer is added, that is to say, when the stopping of the motor 3.

Thus, the drawbacks associated with the variation of the supply voltage due to the load variations are avoided. The power source 9 goes directly into an operating mode that is less costly in energy. This is why, the discharge slope is markedly less pronounced between the instants t1 and t2. The instant t2 represents the moment when the user realizes that the hands 2 of his watch are stopped and decides to recharge the battery or the accumulator 9. The recharging is represented between the instants t2 and t3.

According to a variant of the invention, it is also possible, upon detection of an insufficient supply, to provide a sufficient period of time to avoid the effects of the variation of the load between t1 and t1 + dt, shown in FIG. 3. This period of time can possibly be programmed according to the needs of a user. Of course, other embodiments of an electronic watch according to the invention could also be described to the knowledge of a person skilled in the art without departing from the scope of the invention defined by the claims.

Claims

REVEN DICATIONS

1. Electronic watch comprising analog display means (1), consisting of at least one hand (2) driven by at least one motor (3), a time base (4) for controlling drive means ( 8) of said motor, a rechargeable power source (9), stop means (14) of the motor (3) acting in particular on said drive means (8), time counting means (18) in synchronism with said analog display means (1) for a sufficient supply voltage, characterized in that upon detection of an insufficient supply by said stop means (14), said display means ( 1) are stopped and the corresponding value of said counting means (18) is stored in storage means (19), said counting means (18) continuing to operate, and in that time difference calculation means ( 20) send, as soon as the supply is sufficient again, diff signals No. time (21) between the stored value and the value of the counting means to said drive means (8) for resetting the time of said analogue display means.

2. Electronic watch according to claim 1, characterized in that said engine stop means (14) are actuated for a first threshold voltage corresponding (V _S1 ) to the detection of an insufficient power supply to the engine (3 ) and in that they are kept actuated as long as a second threshold voltage (V _S2 ) greater than the first threshold voltage (V _S ι) has not been reached by the power source.

3. Electronic watch according to claim 2, characterized in that the second threshold voltage (V _S2 ) corresponds to a determined charge level of the power source (9).

4. Electronic watch according to claim 1, characterized in that said stop means (14) are kept actuated for a period of time sufficient to avoid the effects of a variation in charge of the power source, upon detection insufficient food.

5. Electronic watch according to any one of claims 1 to 4, characterized in that the display means (1) are reset when the engine stop means (14) are deactivated, by the shortest path.