Patent Application
20230017243
This application is claiming priority based on European Patent Application No. 21186201.6 filed on Jul. 16, 2021, the disclosure of which is incorporated herein in its entirely by reference.
The present invention relates to a Dewar device for mechanical and/or functional components of a watch, the device comprising a transparent external element.
A watch, such as an electronic watch for example, conventionally comprises a bracelet and a watch case including a plurality of electrical or electronic components. It is known in the prior art that some of these components do not withstand extreme temperatures, and cease to function properly at these temperatures. Typically, liquid crystal displays (LCDs) using light-emitting diodes or quartz crystals tolerate temperatures of up to about 80° C. (degrees Celsius), and down to 0° C. However, in special environments such as that of space or lunar missions for example, temperatures can often reach values of substantially around −150° C. to +125° C.
There is thus a need to be able to use a watch, in particular an electronic watch, in environments where such extreme temperatures may prevail.
The invention relates to a Dewar device for mechanical and/or functional components of a watch, said device being provided with a bracelet and a casing including an enclosure in which a case of said watch is capable of being arranged and at least one fastening device fastening said watch case inside said enclosure of the casing while keeping it away from the set of elements of the casing defining this enclosure, said set comprising at least one transparent external element made of a transparent ceramic material, in particular a transparent polycrystalline ceramic material.
Other features and advantages will become clear upon reading the description given hereinbelow as a rough guide and in no way as a limiting guide, with reference to
This Dewar device 1 comprises at least one transparent external element 10a, such as a crystal/glass or a back. As will be seen hereinbelow, such a transparent external element 10a is made of a material which simultaneously has good mechanical and thermal properties and is resistant to radiation and damage caused by various acids, bases and water, as well as having good transparency. This external element 10a is made of a transparent material that is capable of resulting in a transmission, evaluated by the transmittance Y, of greater than or equal to 68%, or even of greater than or equal to 85%, of light radiation at least comprising visible wavelengths. The term “transparent material” is understood herein to mean a material whose nature, combined with the thickness used, allows for at least partial transmission of the aforementioned light radiation.
Such an external element 10a is made of a transparent, refractory, ceramic material, in particular a transparent polycrystalline ceramic material. This material can consist of the following elements: aluminium oxynitride, alumina-magnesia, yttrium oxide or yttrium aluminium garnet, or a combination of two or more of these elements. More particularly, this external element is manufactured by sintering a rough part, the overall shape whereof is similar to that of the external element 10a. The rough part is essentially formed from a powder or a mixture of powders of ceramic material and, where appropriate, a binder, which after sintering and polishing has transparency characteristics in the visible spectrum. This powder or mixture of powders essentially comprises the transparent ceramic material essentially containing aluminium oxynitride, alumina-magnesia, yttrium oxide and/or yttrium aluminium garnet of aluminium oxynitride. This powder or the mixture of powders can of course, where appropriate, contain a certain number of additives in small quantities in order to obtain parts with specific properties. These additives and the effects thereof are well known to a person skilled in the art.
The external element 10a thus produced is of course completely transparent in the visible spectrum after sintering and helps to protect the case 6 of the watch 3 which is arranged inside the enclosure 5 of the casing 4 and in particular the mechanical and/or functional components 2 contained in this case 6.
This external element 10a, such as the crystal 10a, can be made, for example, according to the manufacturing method described in the French patent No. 2,556,711 which uses, as a starting material, a mixture of powders of ceramic material essentially containing aluminium oxynitride, alumina-magnesia, yttrium oxide and/or yttrium aluminium garnet.
For example, when the ceramic material contains essentially aluminium oxynitride, the composition of this external element is as follows: Al23-1/xO27+xN5-x, where x is comprised between 0.429 and 2.
Such an external element has a Vickers hardness number comprised between 1,223 and 1,632 kgf.mm−2 and preferably of 1,530 kgf.mm−2.
Furthermore, the transmittance thereof for light in the visible spectrum, which is a function of the reflection and absorption of this light, is approximately 85% for a thickness of about 2 mm.
This external element has a light absorption coefficient in the visible spectrum of no more than 65% after sintering and polishing.
Moreover, this transparent external element has, compared to transparent external elements of the prior art made of quartz glass, sapphire glass or plastic glass:
The Dewar device 1 described here is in particular formed by the combination of its casing 4 and the case 6 of the watch 3 in order to procure suitable thermal insulation for these mechanical and/or functional components 2. In this configuration, the case 6 of the watch 3 is arranged inside an enclosure 5 of the casing 4, while being kept away from or at a distance from the set of elements 10a to 10c of the casing 4 defining said enclosure 5, i.e. the external element such as the crystal 10a, an inner peripheral wall 12 of a middle 10c and a back 10b of this casing 4. It should be noted that this inner peripheral wall 12 is also that of said enclosure 5.
This distancing, spacing or separation is configured based on at least one fastening device 7 for fastening the case 6 of the watch 3 inside the casing 4. In other words, the fastening device 7 is capable of configuring a separation between said case 6 and the set of elements 10a, 10b, 10c of the casing 4 forming said enclosure 5 of this casing 4. This fastening device 7 helps to reduce or even eliminate any heat conduction between the inner peripheral wall 12a of the middle 10c and/or the back 10b and/or the crystal 10a with the case 6 of the watch 3, in particular with an overall external face of this case 6. This overall external face includes a top face comprising the crystal 11 of the case 6 of this watch 3, a bottom face comprising a back of said case 6 and an external peripheral wall of a middle of this case 6. It is understood that the bottom and top faces are opposite one another. It should be noted that the fastening device 7 is arranged on an inner peripheral wall 12 of the enclosure of the casing 4. In this configuration, the fastening device 7 mechanically connects, in particular in a reversible manner, the case 6 of the watch 3 to the inner peripheral wall 12 of the enclosure of the casing 4. Moreover, the Dewar device 1 can comprise two fastening devices 7 arranged within the enclosure opposite one another.
It should be noted that such a case 6 is comprised in a watch 3 which can be an electronic watch, for example a quartz watch, or a mechanical watch.
The mechanical and/or functional components 2 of the watch 3, mentioned hereinabove, comprise, in a non-limiting and non-exhaustive manner: a horological movement, a dial, hands, rings, gaskets and/or electronic and/or electrical components 2. It should be particularly noted that such electronic and/or electrical components 2 include, for example, a display device, a processor, a memory, an energy storage component, a motor, an integrated circuit and an electronic oscillator, etc.
Additionally, it should be noted that the main mechanical components are those of the movement and comprise, in a non-limiting and non-exhaustive manner:
It is thus understood that in this configuration, this Dewar device 1 has the same properties and features as a Dewar tube/flask well known in the prior art. As mentioned hereinabove, the properties and features of this Dewar device 1 help to procure good thermal insulation in particular from the extreme temperatures that may prevail in the external environment in which such a device 1 may be located.
In this context, this device 1 thus comprises the casing 4 which includes the middle 10c on which a bracelet is mounted allowing a user of this device 1 to wear it. This casing 4 further includes the transparent external element, in this case the crystal 10a and the back 10b mentioned hereinabove. In this device 1, it should be noted that the crystal 10a preferably comprises a surface which is substantially larger or strictly larger than a crystal 11 of the case 6 of the watch 3.
As seen hereinabove, the crystal 10a, the middle 10c and the back 10b of this device 1 jointly define the enclosure 5 of this casing 4 which is capable of receiving the case 6 of the watch 3. These three elements 10a to 10c of the casing 4, i.e. the middle 10c, the crystal 10a and the back 10b, can be separate elements which are joined together to form this enclosure 5.
Alternatively, the middle 10c and the back 10b of the casing 4 can jointly form a one-piece cast, said one-piece cast defining an opening opposite the back 10b which is capable of being closed by the crystal 10a in a reversible and impervious manner. In an alternative embodiment, the middle 10c and the crystal 10a of the case 4 of the watch 3 can jointly form a one-piece cast, said one-piece cast defining an opening opposite the crystal 10a which is capable of being closed by the back 10b, also in a reversible and impervious manner.
The middle 10c or the back 10b can also be, like the crystal 10a, a transparent external element of the casing 4 of the Dewar device. In such a configuration, the peripheral wall 12 of the middle 10c and the inner face of the back 10b can be coated with a metallic or similar, reflective coating, such as a silver layer.
It should be noted, however, that the middle 10c or the back 10b are preferably made, in a non-limiting and non-exhaustive manner, of a metallic material or of thermosetting or thermoplastic polymer resins reinforced with carbon or glass fibres or even of ceramic materials.
Moreover, the device 1 can comprise an interferometric filter arranged on an overall external face of the casing 4, i.e. on an external peripheral wall of the middle 10c and/or on the external faces of the crystal 10a and the back 10b of this case 6 of the watch 3. This interferometric filter can be a grid or a lattice forming a coating on this overall external face of the casing 4. This grid or lattice has a mesh whose dimensions are such that they allow only certain predetermined wavelengths of the electromagnetic spectrum to pass, typically wavelengths in the visible range. It should be noted that this grid is capable of reflecting at least one ultraviolet and/or infrared or near infrared radiation (NIR).
Moreover, when the device 1 is intended to be used in an environment containing air, the enclosure 5 of the casing 4 comprising the watch case 6 is under vacuum or near vacuum. In other words, in this enclosure, the space defined between this case 6 and the inner peripheral wall 12 of the middle 10c, the back 10b and the crystal 10a is empty or almost empty of material. It should be noted that when this device 1 is used in an airless or substantially airless environment, the enclosure thereof is not necessarily under vacuum, or conversely can also be under vacuum or near vacuum.
Thus, the external element, in this case the crystal, equipping this Dewar device 1, helps to provide the mechanical and/or functional components 2 of the watch 3 with very good thermal insulation from the external environment by reducing or even preventing heat loss by radiation from the components arranged in the watch case 6 over a long period of time. Thus, when the temperature outside the device 1 reaches extreme values, typically of the order of −125 to +125° C., the temperature inside the enclosure 5 remains substantially equal to the temperature present in the case 6 of the watch 3 when it is arranged inside the casing 4, typically of the order of 20° C. It should be noted that whatever the temperature conditions prevailing in the environment of the Dewar device 1, the temperature present in the case 6 of the watch 3 is a temperature that does not hinder the proper functioning of the watch. This temperature is maintained over a period of time which is 5 to 18 times longer than the period of time for which such a watch case would be capable of maintaining an operating temperature of its components 2 when located directly in such an environment where such extreme temperatures prevail (i.e. when located outside the casing of the Dewar device). It is thus considered that such a configuration allows the mechanical and/or functional components 2 of the watch 3 to be protected, and helps ensure that they function optimally under extreme external temperature conditions.
| Number | Date | Country | Kind |
|---|---|---|---|
| 21186201.6 | Jul 2021 | EP | regional |
