EP0899634B1 - Device for immersion in water and comprising a sound transducer - Google Patents

Description

The present invention relates to an apparatus likely to be immersed in a liquid such as water, such as devices worn on the wrist such as than watches. More particularly, the invention relates to such apparatus in the case of which is mounted a sound transducer.

To guarantee the water resistance of watches worn on the wrist at a depth of immersion that can nominally reach thirty meters it is already known to mount an acoustic transducer in the watch case without providing a way of communication between the transducer and the outside likely to conduct sound waves directly (CH-A-375 664). A such mounting has the advantage of guaranteeing very good waterproofness of the watch. On the other hand, the acoustic energy to or from the transducer the full wall of the case, this solution is not possible only if we are satisfied with a poor sound quality. In effect, the usable frequency band is then limited at the frequencies that manage to cross this wall. In practice, we have to work with the frequencies of resonance of the transducer, these frequencies cannot be effectively transmitted through a wall of the housing that if they correspond to a resonant frequency of this wall. This necessarily limits the range of frequencies that can be transmitted and is therefore not suitable reproducing and / or receiving complex sounds such as speech or music. We will also note that such a wall annoyingly dampens the transmission of sounds emitted or received by the transducer.

The object of the invention is to provide an apparatus for type indicated above fitted with a sound transducer so that we can work with a broad spectrum sound, in particular the sound spectrum corresponding to the speech, while ensuring a high degree of tightness.

• ledit transducteur sonore est monté dans ledit boítier en regard d'une membrane déformable le séparant de façon étanche d'une cavité d'entrée qui est ménagée dans ledit boítier et en communication directe avec l'extérieur, et en ce qu'entre la membrane et ledit transducteur sonore est ménagée une chambre intermédiaire admettant une déformation de ladite membrane sous l'action d'une pression statique extérieure et délimitée côté transducteur par un organe de soutien monté fixe dans le boítier et susceptible de limiter la déformation de la membrane en cas d'application de ladite pression statique extérieure.

The invention therefore relates to a waterproof portable device capable of undergoing immersion to a predetermined depth of a liquid such as water, in particular waterproof watch, comprising a housing in which is mounted a sound transducer so as to communicate in a fluid-tight manner with the outside of the housing by means of sound energy, characterized in that

• said sound transducer is mounted in said housing opposite a deformable membrane sealingly separating it from an inlet cavity which is formed in said housing and in direct communication with the outside, and in that between the membrane and said sound transducer is provided an intermediate chamber admitting a deformation of said membrane under the action of an external static pressure and delimited on the transducer side by a support member mounted fixed in the housing and capable of limiting the deformation of the membrane in the event application of said external static pressure.

Thanks to these characteristics, when the switchgear is out of the liquid, the membrane is mounted so that you can vibrate freely under the action of the sound energy to be received and / or emitted. On the other hand, the apparatus being submerged, the membrane can deform under the action of hydrostatic pressure, certainly without ability to transmit sound energy, but protected against any deterioration due to the support provided by the support organ.

• la figure unique montre une vue en coupe partielle d'une pièce d'horlogerie conçue selon l'invention et munie à titre d'exemple d'un transducteur microphonique.

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

• the single figure shows a partial sectional view of a timepiece designed according to the invention and provided, for example, with a microphone transducer.

In the description which follows, the invention will be illustrated in its application to a timepiece such as a wristwatch. It is clear, however, that the invention can be applied to any other apparatus must include at least one sound transducer, the apparatus also being capable of being submerged in a liquid such as water to a depth predetermined. Furthermore, in the example described, the sound transducer is a microphone, however a sound reproduction transducer can also be advantageously used with the invention.

That said, we see represented in the single figure, a sectional view of a wristwatch 1 which is guaranteed sealing up to a predetermined water depth, a depth of 30 m being a predicted value often in convenient.

We recognize from watch 1 in the single figure the case 2, glass 3, hands 4 and 5, dial 6 as well as some parts of the time setting mechanism 7. All these elements, as well as those not visible on the drawing, like integrated circuit, quartz, motor miniature, cog etc. are classic and therefore not to be described here. Although it is not a limiting application of the invention, the apparatus according to the invention provided with the microphone transducer could advantageously be a watch forming a telephone portable.

In the case shown, the apparatus or watch 1 according to the invention, is mounted on a plate 8, the latter resting on the bottom 9 of the housing 2. The plate 8 has an opening 10, of circular shape, in which is mounted microphone 11. This can be of any type suitable, an electret microphone being preferred for its small dimensions. As an indication, such microphone can have a diameter of about 6 mm and a height of about 2 mm.

In the example shown, the microphone itself dit is encased in a cup 12 whose bottom 12a is drilled with holes 13 and acts as a support member. However, it is also possible that the microphone 12 either a simple cylindrical body resting on a plate with through holes.

The opening 10 made in the plate 8 is provided above an inlet cavity 14, of general shape circular and opening out through a right-angled channel 15 to outside.

At the periphery of the external face of the bottom 12a of the cup 12 is bonded a first mounting ring 16 which, with a second mounting ring 17, is intended for hold a circular membrane 18 pinched or fixed with a another way between the two rings. This membrane 18 thus sealingly separates the inlet cavity 14 from a intermediate chamber 19 communicating through the holes 13 with the microphone 11, while transmitting the sound vibrations coming from outside to this one. The mounting ring 16 defines the volume of the chamber intermediate 19. The mounting ring 17 is further axially resting against a shoulder 20 surrounding the inlet cavity 14. According to an alternative embodiment, the membrane 18 can be directly glued or fixed with a other way to ring 16 and ring 17 can be omitted.

In the example shown, the first mounting ring 16 has a radial groove 21 formed in its thickness. The bottom 9 has on its side a groove 22 which follows the groove 21 and which leads to a pressure balancing pad 23. This can be mounted against a radial shoulder 24 provided on the side internal of a hole 25 made in the plate 8 on the external side from which the groove 22 opens. The chamber 19 is thus in communication with the chip 23.

This tablet 23 is impermeable to liquids such as water but it is permeable to gases such as air at provided that the gas pressure changes slowly. all sudden change in gas pressure is therefore blocked by this patch. This can be done by example in sintered Teflon® or ceramic.

In the example described, the case 2 of watch 1 also includes a device 26 communication of its interior space with the exterior. In practice, this is a passage 27 in the plate 8 and bottom 9 and closed by a pad 28 which, like the pad 23, is impermeable to liquids such as water, but permeable to gases whose pressure varies slowly. It can be made in the same material as tablet 23.

• la rainure 22 peut être omise, et le gaz diffuser par un chemin de fuite entre la surface frontale de la bague 16 et la surface du fond 12a;
• il peut n'y avoir qu'une seule communication avec l'extérieur à travers une pastille telle que la pastille 28 montée comme représentée sur la figure, la rainure 22 communiquant avec l'intérieur de la montre;
• la coupelle 12 peut être montée dans son logement du boítier 2 de manière à laisser un chemin de fuite le long de sa paroi extérieure pour faire diffuser les gaz à faible variation de pression vers l'extérieur le long de sa paroi extérieure.

Several variants can be envisaged to put the chamber 19 in communication with the outside only for very small variations in the gas pressure. So :

• the groove 22 can be omitted, and the gas diffusing through a leak path between the front surface of the ring 16 and the bottom surface 12a;
• there can be only one communication with the outside through a pad such as the pad 28 mounted as shown in the figure, the groove 22 communicating with the interior of the watch;
• the cup 12 can be mounted in its housing of the housing 2 so as to leave a leak path along its outer wall to diffuse the gases with low pressure variation outward along its outer wall.

The device thus arranged for communication of the intermediate chamber 19 with the outside only for slow variations in static gas pressure surrounding, keeps the membrane 18 operational, even if the watch is brought by the carrier at different altitudes or is carried in climatic conditions inducing such variations slow.

It can be noted that in a way the pads 23 and 28 constitute low-pass filters which do not allow passage that variations in the pressure of gases such as air, very low frequency, typically 1/10 Hz and less.

It should be noted that in the present example of realization, room 19 is first in communication with the inside of box 2 and cannot communicate with outside (always only for low static gas pressure) only through the communication device 26. This arrangement is preferred here since the watch described may include other organs also requiring compensation slow pressure. It can be for example a sound reproduction transducer. The placing device in communication 26 can then be used for both transducers at the same time, which minimizes places in the case where communication to the exterior exists for gases such as air.

The membrane 18 is made of a little material elastic and it is not stretched between the rings of mounting 16 and 17 in order to guarantee freedom of vibration as wide as possible. Material particularly suitable for membrane 18 is the Mylar®, its thickness can be between 2 and 50 µm, a preferred value being 10 µm. Its diameter is one little higher than that of microphone 11. Note that a such a membrane can transmit vibrations in a frequency range from 200 Hz to 5 kHz.

The behavior of the membrane 18 is as follows.

When the watch is worn out of the water, the membrane 18 has a flat configuration in which it is distant from the grid formed by the bottom 12a of the cup 12. It can thus transmit without disturbances sound vibrations coming from outside to room 19 and from there to microphone 11 at through the holes 13 made in the bottom 12a.

However, when the watch comes to be submerged, the membrane 18 will deform due to an abrupt variation of the differential pressure, to assume a curved shape towards the bottom 12a, the path of pressure compensation described above not reaching fairly quickly to balance the difference in pressures. From a certain hydrostatic pressure value, the deformation of the membrane will be such that it will apply against the bottom 12a of the cup 12, this last forming an effective support preventing any deterioration, and in particular an irreversible deformation, membrane 18.

Note that in the case where the transducer is a speaker, the characteristics of the membrane including thickness, diameter and material of which it is incorporated, will be adapted accordingly.

Claims (12)

1. Portable water resistant device capable of undergoing submersion to a predetermined depth in a liquid such as water, in particular a water resistant watch, including a case (2) in which is mounted an acoustic transducer (11) so as to communicate in a water tight manner with the exterior of the case (2) via acoustic energy, characterised in that

   said acoustic transducer (11) is mounted in said case (2) facing a membrane (18) which is able to be deformed, separating it in a water tight manner from an inlet cavity (14, 15) which is arranged in said case (2) and in direct communication with the exterior, and in that between the membrane (18) and said acoustic transducer (11) an intermediate chamber (19) is arranged, allowing deformation of said membrane by the action of external static pressure and delimited on the side of the transducer by a support element (12a) fixedly mounted in the case and capable of limiting the deformation of the membrane in the event of application of said external static pressure.
2. Device according to claim 1, characterised in that said support element is a plate (12a) pierced with holes (13) to allow the passage of the acoustic energy transmitted from said inlet chamber (14, 15) via said membrane (18) or transmitted in the opposite direction.
3. Device according to claim 2, characterised in that said plate constitutes the bottom (12a) of a housing (12) in which said acoustic transducer (11) is arranged.
4. Device according to any one of claims 1 to 3, characterised in that said membrane (18) is held between two mounting rings (16, 17) fixed onto said support element (12a), the ring (16) situated on the side of said transducer (11) determining internally the volume of said intermediate chamber (19).
5. Device according to claim 4, characterised in that said intermediate chamber (19) is placed in communication with the exterior through means (23) only allowing a flow of gas in the presence of slow variations in the differential pressure between said intermediate chamber (19) and the exterior.
6. Device according to claim 5, characterised in that said means allowing a flow of gas are formed by at least one pressure balancing membrane (23).
7. Device according to claim 5, characterised in that said means allowing a flow of gas are formed by an escape path connecting said intermediate chamber (19) to the exterior.
8. Device according to claim 6, characterised in that said intermediate chamber (19) communicates with the interior of said case (2) through a first of said pressure balancing membranes (23) and in that the internal volume of said case (2) communicates with the exterior through a second of said pressure balancing membranes (28).
9. Device according to any one of claims 1 to 8, characterised in that said membrane (18) is made of Mylar®.
10. Device according to claim 9, characterised in that said membrane (18) has a thickness selected between 2 and 50 µm, and preferably a thickness of 10 µm
11. Device according to any one of claims 6 and 8 to 10, characterised in that said pressure balancing membrane is made of sintered Teflon® or ceramics.
12. Device according to any one of the preceding claims, characterised in that said acoustic transducer is a microphone (11) or a loud-speaker.

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