EP1141788B1 - Watch providing barometer and altimeter reading, and method for making same - Google Patents

Abstract

The invention concerns a wristwatch comprising in its case a resistive piezoelectric pressure and temperature sensor (26) exposed to a pressure chamber (42) communicating with the outside environment, for measuring ambient pressure. In order to provide individual calibration depending on temperature followed by a permanent correction of the sensor pressure signals, the latter is fixed to the lower surface of a printed circuit card (30) bearing the electronic circuits (35) processing the sensor signals. The calibration parameters are recorded in a non-volatile memory (36) of said circuits. A rigid and sealed separating partition (43) forms an internal floor separating the pressure chamber (42) from the watch sealed part.

Description

The present invention relates to an electronic watch providing a barometric or altimetric indication based on the ambient pressure and having the features of the preamble of claim 1.

The invention also relates to a method of manufacturing such a watch.

Electronic watches of this kind are known, in particular by the patent US 4,835,716 or by the patent application EP 640 896 , which provides the analog display of the atmospheric pressure, the trend of this pressure and the altitude by hands on the dial of the watch.

In this type of barometer and / or altimeter watch, the implantation of the pressure sensor poses problems of space, tightness, electrical connection and internal deformations due to the pressure differences between the sealed part and the chamber. pressure where prevails the ambient pressure, that is to say the atmospheric pressure, to which is added the hydrostatic pressure if the watch is immersed in water.

The case of the first electronic barometer and / or altimeter watches included a side appendage specifically designed to contain the pressure sensor and having communication ports with the outside. See for example patents US 4,783,772 and EP 345 929 . This solution had the advantage of preserving the sealing system of traditional watch cases, but this appendix was unsightly and sometimes embarrassing. It has therefore been necessary to implant the pressure sensor inside a watch case of ordinary shape, which requires a pressure chamber in the housing. This results in additional difficulties in sealing and compressive strength within this housing.

For example in the watch described in the EP 640 896 , the pressure sensor is housed in the housing in the vicinity of the middle part, under a platen of the clockwork against which it is maintained applied. A small pressure chamber is formed between the top of the sensor and the plate and communicates with the outside via a channel that passes through the plate and the middle and opens under a rotating bezel. A cover disposed between the bottom of the housing and the sensor carries electrical connections connecting the latter to an integrated circuit located next to the sensor and processing the signal to provide barometric and / or altimetric indications. Additional electrical connections are required to connect this integrated circuit to the other electrical circuits of the watch, particularly to those controlling the display.

This known construction takes considerable room in height and requires special provisions to seal around the pressure chamber and around the channel connecting it to the outside.

On the other hand, there is a problem of variation of the sensor output signal as a function of temperature. This variation is different from one sensor to another of the same type. For a variation of 10 ° C, the altimetric indications provided with piezoresistive sensors commonly used, relatively inexpensive, may have differences of up to about 100 m altitude.

The applicant has devised to calibrate each sensor as a function of temperature variations, to calculate signal calibration parameters and to record them in the electronic circuits associated with this sensor, but such a method would be excessively costly in a manufacturing process. of a watch according to the EP 640 896 because it could be applied only once the sensor and the associated electronic circuits are joined, that is to say after their mounting in the housing.

In the patent application EP 670,532 , there is provided an inner bottom separating the inside of the case of the watch into a sealed portion, which contains the movement of the watch, and a pressure chamber which is located between the inner bottom and an outer bottom pierced with several holes. The inner bottom carries a pressure sensor that is electrically connected to the electronic control of the movement by a flexible contact tab to absorb a flexion of the inner bottom under the effect of pressure. However, this construction has a relatively large thickness and does not solve the aforementioned problem of calibration.

The present invention aims to avoid the aforementioned drawbacks and relates to a watch, in particular a wristwatch, allowing an individual calibration of the indications provided by an inexpensive pressure sensor, and this thanks to an adequate construction and a manufacturing method. economically acceptable.

An additional object of the invention is to arrange the watch so as to ensure a good seal and avoid problems due to deformations resulting from variations in the ambient pressure in the pressure chamber.

According to a first aspect of the invention, there is provided an electronic watch of the kind defined above, characterized in that the pressure sensor is attached to the printed circuit board provided with time-keeping circuits and electronic circuits.

These characteristics make it possible to associate, at an early stage of manufacture, the pressure sensor with the electronic circuits intended to process its output signal. Thus, it can be provided that temperature measuring means are installed on the printed circuit board and that the electronic circuits comprise a non-volatile memory in which individual calibration parameters of the pressure sensor are recorded, and it is possible to determine these parameters and save them in the memory before assembly of the instrument, as will be explained later.

However, it should be noted that the invention can also be implemented in an instrument devoid of means for measuring the temperature, thus also without the use of a memory for individual calibration parameters of the pressure sensor, either because a lower accuracy of the pressure measurement is accepted, either because a thermocompensated or low temperature drift pressure sensor becomes available at an acceptable price.

The separation means comprise a partition wall having an opening in which said sensor is placed. Preferably this partition is connected to the housing sealingly along its periphery.

This conveniently divides the inside of the housing into a sealed portion and a pressure chamber of any shape and size. This partition supports the effect of the external pressure in the pressure chamber and thus protects the plate supporting the organs display and, where appropriate, the watch movement in the sealed part. The partition wall can easily be connected to the housing in a sealed manner along its periphery, in the manner of a double bottom, and the pressure chamber extending between this double bottom and the bottom of the housing can advantageously contain a transducer electro-acoustic arranged to emit sounds in this room that communicates with the outside.

The sensor used is preferably a piezoresistive type pressure and temperature sensor comprising Wheatstone bridge-connected resistors in which the bridge resistance varies only as a function of temperature, while the pressure variations create an imbalance of the temperature. bridge

1. a) fabriquer la carte à circuits imprimés et monter au moins le capteur de pression et lesdits circuits électroniques sur cette carte pour former un sous-ensemble;
2. b) étalonner ledit sous-ensemble dans différentes conditions de température et de pression et déterminer des paramètres de calibrage du capteur en fonction des ces conditions;
3. c) enregistrer les paramètres de calibrage dans la mémoire non volatile des circuits électroniques;
4. d) le cas échéant, compléter le sous-ensemble par d'autres éléments devant être supportés par la carte à circuits imprimés; et
5. e) monter dans le boîtier ledit sous-ensemble et les autres composants de la montre.

Another aspect of the invention relates to a method of manufacturing a watch as defined above, wherein said electronic circuits comprise a non-volatile memory for recording individual calibration parameters of the pressure sensor, the method comprising the successive steps of:

1. a) fabricating the printed circuit board and mounting at least the pressure sensor and said electronic circuitry on this board to form a subassembly;
2. b) calibrating said subassembly under different temperature and pressure conditions and determining calibration parameters of the sensor according to these conditions;
3. c) save the calibration parameters in the non-volatile memory of the electronic circuits;
4. (d) where appropriate, supplement the subassembly with other elements to be supported by the printed circuit board; and
5. e) mounting in the housing said subassembly and the other components of the watch.

• la figure 1 est une vue de dessus d'une montre-bracelet réalisée selon la présente invention,
• la figure 2 est une vue en coupe schématique de la montre de la figure 1 suivant la ligne II-II, sans la lunette tournante,
• la figure 3 est une vue en coupe schématique de la montre de la figure 1 suivant la ligne III-III, sans la lunette tournante, et
• les figures 4 et 5 représentent en perspective respectivement le dessus et le dessous d'une cloison de séparation faisant partie de la montre de la figure 1.

Other features and advantages of the invention will appear in the following description of a preferred embodiment, presented by way of non-limiting example and with reference to the accompanying drawings, in which:

• the figure 1 is a top view of a wristwatch made according to the present invention,
• the figure 2 is a schematic sectional view of the watch of the figure 1 along line II-II, without the rotating bezel,
• the figure 3 is a schematic sectional view of the watch of the figure 1 along line III-III, without the rotating bezel, and
• the Figures 4 and 5 represent in perspective respectively the top and the bottom of a partition wall forming part of the watch of the figure 1 .

The watch represented in Figures 1 to 3 comprises a housing 1 comprising a middle 2, a removable bottom 3 mounted on the middle with a compressible gasket 4, and a glass 5 fixed to the middle and covering a dial 6. The middle part 2 supports a rotating bezel 7 bearing azimuth markers 8. The telescope was removed from the Figures 2 and 3 to simplify the drawings. Conventionally, external control members are provided in the form of three lateral push-buttons 10, 11 and 12. The casing 1 is attached to a bracelet 13. For the analog time display, a needle is provided for 14 hours and a minute hand 15 which cooperate with a conventional time scale 16 on the dial 6. These needles are also used to display other indications, as will be described later. In addition, a digital display is formed by a liquid crystal cell (LCD) 17 preferably placed under a transparent window of the dial 6 and intended to display timed times obtained in a conventional manner by manipulation of the pushers 11 and 12, as well as other values which will be mentioned later.

The watch described here is also an electronic instrument performing various measurement or indication functions in addition to measurements or time indications. These additional functions, more precisely the corresponding operating modes of the watch, are represented on the dial 6 by symbols 20 to 23, while another symbol 24 (TIME) represents the conventional time display mode of the watch. In this example, the user activates the desired mode by means of capacitive control devices comprising transparent electrodes (not shown) fixed under the glass 5 above the corresponding symbols 20 to 24. Such control members are well known. and are described in particular in patent publications JP 49-13168 A , CH 607 872 and EP 674 247 . However, it is possible to provide different control members within the scope of the present invention.

The thermometer symbol 20 represents a display mode of the ambient temperature, which is indicated numerically by the LCD cell 17. This temperature is measured by means of a pressure and temperature sensor 26 which will be described more far. The symbol 21 comprising a cloud and a sun corresponds to a mode of indicating the barometric tendency, indicated by the needles 14 and 15 superimposed and brought near the cloud or the sun. This trend is calculated from the pressure indications provided by the sensor 26. The mountain-shaped symbol 22 corresponds to an altitude display mode, which is indicated numerically on the LCD cell 17. This altitude is calculated from from barometric indications obtained using the sensor 26. The symbol 23 in the form of a compass rose corresponds to a compass function, that is to say the indication of the north by means of the needles 14 and 15 put in an aligned position and making it possible to read an azimuth on the telescope 7. This direction is determined by means of a magnetic field direction sensor 27, incorporated in the instrument for example as described in the patent publication. EP 713 162 . Since the present invention essentially relates to the means used to provide barometric or altimetric indications, the other functions of the watch will not be described in detail here. It will also be noted that such a watch may also include other functions, for example a chronograph, an alarm at a predetermined time or at a predetermined altitude, an indication of the end of battery life, a radio time-out. ordered, receiving paging, etc.

• des circuits garde-temps représentés schématiquement par la référence 31 et comprenant en particulier un résonateur à quartz et un circuit intégré,
• un moteur pas-à-pas 32 à deux rotors entraînant respectivement deux arbres de sortie concentriques 33 et 34 qui portent les aiguilles 14 et 15,
• des circuits électroniques 35 pourvus d'une mémoire non volatile 36 (par exemple du type EEPROM) et destinés à traiter les signaux de sortie du capteur 26,
• le capteur magnétique 27,
• d'autres circuits électroniques non représentés, destinés à traiter les signaux du capteur magnétique 27,
• et une entretoise 37 fixée au cadran 6 et supportant un rehaut 38 et la cellule LCD 17.

As can be seen particularly in Figures 2 to 5 the watch contains a printed circuit board 30 which also serves as a platinum for the electronic watch movement. For this purpose, the card 30 has a relatively rigid and thick substrate, for example about 1.0 mm. On the upper face of the printed circuit board 30 are mounted in particular:

• time-keeping circuits diagrammatically represented by the reference 31 and comprising in particular a quartz resonator and an integrated circuit,
• a two-rotor stepper motor 32 respectively driving two concentric output shafts 33 and 34 which carry the needles 14 and 15,
• electronic circuits 35 provided with a non-volatile memory 36 (for example of the EEPROM type) and intended to process the output signals of the sensor 26,
• the magnetic sensor 27,
• other electronic circuits, not shown, for processing the signals of the magnetic sensor 27,
• and a spacer 37 attached to the dial 6 and supporting a flange 38 and the LCD cell 17.

Screws 39 secure the card 30 to the spacer 37. Printed circuits on the upper face of the card 30 provide the electrical connections between the elements 31, 32, 35 and 36, as well as connections with the switchgear elements. control described above and with contactors such as 29 arranged on the periphery of the card and actuated by the pushers 10 and 12.

The lower face of the card 30 also carries printed circuits which are connected to those of the upper face, to the sensor 26 and to power connections connecting these circuits to a battery 40 housed in the lower part of the housing 1.

The inside of the case of the watch is divided into a sealed part, which contains in particular the printed circuit board 30 and all the elements placed between the latter and the ice 5, and a pressure chamber 42, by means of separation comprising mainly a rigid partition wall 43 whose periphery is connected to the middle part 2 in a sealed manner by means of an O-ring 44. The upper face of the partition 43 has, along said periphery and around the region of the sensor 26 , a horizontal bearing surface 45 which bears against the card 30 and, via the latter, against a suitable shoulder 46 of the middle part 2. The card 30 is fixed to the partition 43 by means of screws shown, screwed into thick parts such as 47 of the partition. Outside the bearing surface 45, the upper face of the partition 43 is slightly hollowed so as to leave a small vertical gap 48 between it and the card 30. This allows the partition 43 to bend under the effect of the external pressure without the risk of deforming the card 30 constituting the platen of the movement of the watch.

As the partition 43 may be relatively thick, for example as much as the stack 40, it will be rigid enough to withstand high pressures, especially in a watch for divers. It can be made of both synthetic material and metal. The internal structure formed by the partition 43, the card 30 and the spacer 37 is fixed in the casing 1 by means of conventional unrepresented flanges, which are fixed to the middle part 2 and bear against the underside of the casing 1. partition 43 for pressing said structure against the shoulder 46.

The sealed portion of the housing interior contains air or other gas. The pressure chamber 42 contains air and communicates with the atmosphere through one or more orifices 49 formed for example through the periphery of the bottom 3, so that it is always subjected to the external ambient pressure.

As we see in the Figures 4 and 5 the partition 43 has three openings 51, 52 and 53 in which the stack 40, the pressure and temperature sensor 26 and an electroacoustic transducer 54 for providing an audible signal to the user respectively take place. This transducer comprises a vibrating plate 55 bonded to the partition 43 and a piezoelectric ceramic element 56 fixed to the plate 55 on the side of the sealed portion of the watch.

The opening 52 receiving the sensor 26 is in the vicinity of the periphery of the partition 43, the bearing surface 45 of this partition applying against the card 30 all around this opening. As a possible bending of the partition 30 would have only a small amplitude in this peripheral zone, it is not to be feared that it deforms excessively the card 30 serving as platinum of the clockwork movement.

The battery 40 is slidably inserted into an annular-shaped battery holder 57 fixed to the underside of the card 30. It is separated from the pressure chamber 42 by a cap 58 sealingly engaged in the opening 51 of the partition 43, by means of an O-ring 59. The cap lined with a shield 60 internally arranged to prevent magnetic influences of the battery on the magnetic sensor 27. The cap 58 can be fixed to the partition 43 by a system to bayonet or maintained by other appropriate means.

Thus, it is noted that the plate 55 and the cap 58 cooperate with the partition 43 to divide the inside of the housing into two parts in the present example. However, these elements could be arranged differently and not be part of the separation means.

The pressure and temperature sensor 26 is a piezoresistive sensor of the known and inexpensive type, made of a micro-machined silicon element comprising a membrane, one face of which is exposed to the ambient pressure prevailing in the pressure chamber. , while the other side carries resistors connected in Wheatstone bridge, as provided for example in the patent US 4,783,772 . In this case, the resistors are arranged in such a way that the overall strength of the bridge varies. only as a function of temperature, while the pressure variations create an imbalance of the bridge, resulting in variations in the voltage between its two output terminals. Thus, by bonding wires 60 connecting it directly to the board 30, the sensor 26 provides the integrated circuit 35 with output signals representing both the pressure and the temperature at which the sensor is exposed. This sensor may for example be of the AM761 type marketed by Intersema Sensoric in Bevaix, Switzerland.

The sensor 26 is protected by means of a ring 61 bonded to the card 30 and engaged in the opening 52 of the partition 43, and a silicone gel 62 which also coats the wires 60. This gel is electrically insulating and Water-proof. An O-ring seal 63 is compressed, preferably axially, that is to say parallel to the central axis 65 of the watch, between the ring 61 and a rim of the partition 43, and its central portion is closed. in a sealed manner by a flexible membrane 64 which allows the pressure to be transmitted from the chamber 42 to the gel 62 and the sensor 26. It will be noted that this membrane is optional, but it has the advantage of preventing the gel 62 displaces or is polluted. In a variant, the membrane-free seal 63 could be placed directly between the card 30 and the partition 43, in an annular recess formed around the upper edge of the opening 52.

A significant advantage of the construction described above is that the partition wall 43, with the elements 55, 58, 63 and 64 closing its three openings, constitutes a rigid and watertight inner bottom which protects all the electrical and watch components of the shows against the pressure and the external agents and allows to provide, between it and the true bottom 3 of the housing, a pressure chamber which covers the entire extent of the bottom 3 and allows to fix it to the middle part 2 of a simple and easily removable way, since the bottom 3 is not stressed by the external pressure. As a result, the replacement of the battery 40 is easy and does not affect the inner elements of the watch. In addition, the sound signals emitted by the transducer 54 in the pressure chamber 42 can easily propagate outward without having to cross the bottom 3 itself.

Another important advantage, already mentioned above, lies in the fact that the pressure and temperature sensor 26 is electrically fixed and electrically connected directly to the printed circuit board 30 carrying them. electronic circuits 35 associated with this sensor. This makes it possible to incorporate into the manufacturing process, inexpensively, a step of individual calibration of the pressure signal as a function of the temperature signal supplied by this same sensor (or possibly by a separate temperature sensor). also mounted on the same printed circuit board). Since the manufacturing process provides for each watch a subassembly comprising at least the printed circuit board 30, the pressure and temperature sensor 26 and the associated electronic circuits 35 arranged to receive and process the output signals of the sensor, can easily, before assembly of the watch and even before the card 30 is equipped with other components such as the motor 32 or the quartz resonator, place a batch of such subsets under predetermined conditions of temperature and humidity. pressure in an enclosure, measure the output signals of each sensor 26 before and / or after their processing by the electronic circuits 35, determine individual calibration parameters of the signals of this sensor for the subsequent correction of these signals by the circuits electronics, and save these calibration parameters in the nonvolatile memory 36 so that the electronic circuits 35 can use constantly thereafter.

As obtaining a uniform and stable temperature of the parts contained in the enclosure is quite long, the batch processing has the advantage of ensuring high productivity, a lot may include several hundred subsets which are all electrically connected to a common support for transmitting the signals to the calibration apparatus. The latter can thus calibrate and control the subsets in succession at a high rate.

Then, the subassemblies thus calibrated can be completed by the other elements to be supported by the card 30. With the construction described above, each card 30 serving platinum will then be fixed on the one hand to the spacer 37 and on the other hand to the partition wall 43, the dial and hands will be mounted, then the assembly can be placed in the housing from the bottom. It will also be noted that, in this method of assembly, the fact that the seal 63 is compressed in the axial direction represents a great ease of assembly and guarantees a good long-term sealing performance in the area of the assembly. As the clamping of the gasket 63 is guaranteed by the screws fixing the card 30 to the partition 43, it is independent of the mode of attachment of these two elements to the housing.

Since the pressure values calculated in the conventional manner from the output signals of the sensor 26 are corrected using the calibration parameters determined individually for this sensor, the watches thus manufactured are capable of providing barometric and altimetric indications. more accurate than the watches according to the prior art cited above. The applicant has observed that for a variation of 10 ° C, a range of dispersion of about 100 m on the altitude measurements can thus be reduced to less than 5 m, for example about 3 m.

Claims (14)

1. Electronic watch providing a barometer or altitude reading based on ambient pressure and including:

   - a case (1) the interior of which is divided by separating means into a sealed part and a pressure chamber (42) which communicates with the outside of the case so as to receive the ambient pressure, said separating means including a separating wall having an opening (52)

   - an electric power source (40),

   - a pressure sensor (26) having one side exposed to the pressure prevailing in the pressure chamber, this sensor (26) being located in said opening (52),

   - display means (14, 15, 17) for supplying a time indication and said barometer or altitude reading, and

   - a printed circuit board (30) disposed in the sealed part of the case and provided with time-keeping circuits (31) and electronic circuits (35) arranged to receive and process an output signal from the pressure sensor and to control the barometer or altitude reading display means, the pressure sensor (26) being directly connected via electrical connections to said printed circuit board (30)

   characterised in that the pressure sensor (26) is secured to said printed circuit board (30) provided with said time-keeping circuits and said electronic circuits.
2. Watch according to claim 1, characterised in that temperature measuring means are installed on the printed circuit board and in that said electronic circuits (35) include a non volatile memory (36) in which are stored individual calibrating parameters of the pressure sensor (26) as a function of the temperature.
3. Watch according to claim 1 or 2, characterised in that the display means include analogue display means.
4. Watch according to claim 3, characterised in that the printed circuit board (30) is rigid and constitutes a plate supporting, on the opposite side to the pressure sensor, at least an electric motor (32) for the analogue display means.
5. Watch according to any of the preceding claims, characterised in that said separating wall (43) is connected to the case in a sealed manner along its periphery.
6. Watch according to claim 5, characterised in that said opening (52) is located in proximity to the periphery of the separating wall.
7. Watch according to claim 6, characterised in that outside the pressure sensor zone, there is a gap (48) allowing the separating wall (43) to bend arranged between said wall and the printed circuit board.
8. Watch according to any of claims 5 to 7, characterised in that sealing means (61, 63) between said wall (43) and said board (30) are arranged in or around said opening (52).
9. Watch according to claim 8, characterised in that a ring (61) surrounding the pressure sensor laterally is bonded to the printed circuit board and extends into the opening (52) of the separating wall, said sealing means including a sealing gasket (63) inserted between said ring and said wall.
10. Watch according to claim 9, characterised in that said sealing gasket 63 is associated with a sealed membrane (64) which separates the pressure sensor from the pressure chamber.
11. Watch according to any of claims 5 to 10, characterised in that the pressure chamber (42) extends between the separating wall (43) and a back cover (3) of the case.
12. Watch according to claim 11, characterised in that it includes an electro-acoustic transducer (54) arranged to transmit sounds into the pressure chamber.
13. Watch according to claim 2, characterised in that the sensor (26) is a pressure and temperature sensor of the piezo-resistive type including resistors connected in a Wheatstone bridge where in the bridge resistance varies only as a function of temperature, while pressure variations create an unbalance in the bridge.
14. Method for manufacturing a watch according to claim 2, including the successive steps of:

    a) manufacturing the printed circuit board and mounting at least the pressure sensor (26) with the temperature measuring means and said electronic circuits (35) on this board to form a sub-assembly;

    b) calibrating said sub-assembly in different temperature and pressure conditions and determining sensor calibrating parameters as a function of such conditions;

    c) storing the calibrating parameters in the non volatile memory (36) of the electronic circuits;

    d) if necessary, completing the sub-assembly with other components which have to be carried by the printed circuit board; and

    e) mounting said sub-assembly and the other watch components in the case (1).

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