EP0718211A1 - Desiccation capsule and article provided with the same - Google Patents

Abstract

The capsule has a first compartment (27) containing a desiccation product (30) capable of absorbing moisture and having an aperture (25) in one face (22), covered by a membrane (23) which allows moisture to pass through it while retaining the product. It has a second compartment (28) which is connected to the first one through the aperture (25) and has a second aperture (26) in its other face (31). The first compartment has a transparent partition (29) at one end to allow the colour and/or state of the desiccant product to be viewed. The capsule is fitted in a non-permanent manner, eg. by a clip or thread, to an article which is to be protected against humidity, eg. a watch, camera, package or electronic apparatus.

Description

The present invention relates to a desiccation capsule comprising a compartment intended to contain a desiccant capable of absorbing moisture, the said compartment being provided on a first face with a first opening closed by a membrane allowing moisture to pass through, but retaining the undissolved desiccant. The present invention further relates to articles, such as watches, cameras, packaging means, etc., comprising a housing defining the interior and exterior of the article, the interior of which must be protected. moisture.

A growing number of items and devices need to be permanently protected from moisture damage. This is particularly the case for electronic devices, especially portable devices, such as watches, calculators, computers, photocopiers, recording, transmission and / or sound or image reproduction devices, for example cameras, camcorders, video recorders, telephones, portable music players, radios, amplifiers, etc. This is also the case for many mechanical devices, for example certain watches or certain musical instruments, electrical devices such as motors, lighting devices, cupboards electrical or optical devices such as binoculars or objectives. This can also be the case of articles constituting means for packaging sensitive parts, for example cardboard boxes, cases or bags for transporting any type of object sensitive to humidity. In general, the invention can be applied to practically all articles comprising a housing defining the interior and exterior of the article, the interior of the article, or the object disposed inside the article. item may suffer from moisture.

A technique sometimes adopted to protect the interior of the article is to make the case as waterproof as possible. This technique is best suited for items that do not need to be opened often, such as watch cases. However, it has also been used to protect portable music players, binoculars or cameras, in particular photographic cameras or cameras, for example.

Despite advances in the sealing technique, and in particular in the seal technique, it is difficult to provide truly safe and durable protection of the interior of the device housing or article against moisture damage, especially against corrosion. Seals have aging problems and lose part of their tightness after a few years. On the other hand, the seal may undergo accidental deterioration following an impact for example.

Certain articles, although also requiring protection, can only be very difficult to make waterproof, or at a cost that is disproportionate to the value of the article to be protected. These items must therefore be protected by keeping them permanently in a low humidity environment, which can be difficult. This is the case, for example, of boxes used for the storage or transport of sensitive objects, but also of most usual electronic devices.

Patent CH215706 (April 19, 1940) describes a waterproof watch whose case contains a desiccation capsule. This capsule contains a desiccant capable of absorbing moisture that may have entered the watch. The desiccation capsule protects the watch mechanism even when the seals have failed to seal.

Patents US2463315 (March 1, 1949), CH384690 (December 31, 1956), US3939646 (February 24, 1976), and JP58061561 (April 12, 1983) describe various other means of placing a certain amount of desiccant inside a housing shows, showing that research efforts have been made for a very long time to find a solution to this problem. None of these solutions was however able to prevail, due to disadvantages which prevented any commercial success.

Neither of these solutions makes it easy to detect whether moisture has entered the article and whether the capsule must be replaced. If the waterproofness of the case has become defective and water thus easily enters the watch, the capsule can only fulfill its role as long as its absorption capacity is not exceeded. It must then, or even if possible before this time, be imperatively replaced or regenerated, for example by heating. There is nothing, however, in these embodiments to detect when the capsule must be regenerated. In addition, this regeneration or replacement requires in all these embodiments to dismantle the housing and must therefore be carried out by a specialist.

Patent CH314386 (December 22, 1953) describes a waterproof watch comprising a tablet containing a material sensitive to humidity. The tablet is visible from the outside and a change in the color and / or appearance of the material thus signals to the user of the watch that moisture has penetrated the case. However, this tablet only functions as a control, but not as a desiccant and does not have the function of absorbing moisture. When the pastille changes color, it is therefore necessary to have the watch repaired, which may already have suffered possibly irreparable damage.

One of the aims of the invention is therefore to propose a drying capsule which avoids these problems, and which clearly indicates to the user when it must be replaced.

Another object is to provide a simple and economical, but effective and efficient desiccation capsule construction which can be adapted to various types of articles with an internal volume possibly very different.

To do this, the invention proposes to produce a desiccation capsule comprising a transparent wall making it possible to see from the outside of the article the color and / or the appearance of the desiccant product contained in the capsule, the capsule then being able to be easily disassembled thanks to non-permanent fixing means.

A product which changes color during the absorption of moisture, for example CuSO 4, will therefore preferably be used as desiccant. This also avoids other problems associated with the products used in the embodiments mentioned, of the SiO ₂ type, which have a relatively low volume absorption capacity for moisture, and which consequently require desiccation capsules with large dimensions. , which can be very difficult to integrate aesthetically in certain articles, in particular in a watch case. In addition, the color variation of Si0 ₂ during moisture absorption is low, making it a poor visual moisture detector.

The problems mentioned are thus solved by virtue of the new features of claim 1.

Most common desiccants are corrosive and attack the metal capsule that contains them. In the devices of the aforementioned art, these products are at best separated from the interior of the housing of the device at best by a semi-permeable membrane which, in normal situation, retains the desiccant product but lets moisture pass in liquid form or carbonated. When moisture enters the housing, this moisture passes through the semi-permeable membrane and is absorbed by the desiccant. Unfortunately, the desiccant dissolves in the water and in this way manages to cross the membrane in the opposite direction. Traces of the product thus leave the capsule and spread inside the case of the article, attacking the mechanism by corrosion and creating points of fixation of humidity. This problem is especially important when a small diameter desiccation capsule is used to quickly dry a very humid volume of air. In this situation, in fact, the semi-permeable membrane, of small surface, is completely impregnated with water and remains moist at least until all the water has been absorbed by the desiccant.

According to a characteristic of the invention, the desiccation capsule comprises a first compartment containing the desiccant and a second compartment separated from the first by a semi-permeable membrane and provided with a second opening connecting it with the interior of the article. . This second compartment functions as an airlock which retains the dissolved desiccant inside and prevents it from spreading throughout the case of the article or device to be protected.

According to another characteristic of the invention, the capsule can be provided with a removable plug obstructing the second opening. This stopper allows you to transport and store the desiccation capsule before installing it on the article to be protected. The cap is preferably removed just before installing the capsule in the article housing.

The invention also relates to articles which can be protected by desiccation capsules of this type.

The invention will be better understood using the description and the appended figures:

FIG. 1 represents a first type of desiccation capsule adapted in particular to a watch middle.

Figure 2 shows in detail a desiccation capsule of the first type.

FIG. 3 represents another view of the desiccation capsule of the first type.

FIG. 4 represents a second type of desiccation capsule adapted in particular to a middle part of a watch.

FIG. 5 represents a third type of desiccation capsule, more particularly suitable for articles of greater internal volume.

FIG. 1 represents a first type of desiccation capsule 20, in particular adapted to be integrated into a middle part 11 of a watch 10. The capsule comprises a first compartment 27 containing, as desiccant 30, copper sulphate CuS0 ₄ . In addition to a large volume absorption capacity for moisture, which allows the capsule to be miniaturized, CuS0 ₄ has the advantage of rapidly changing from white to bright blue when it is brought into contact with moisture. It thus constitutes an effective visual humidity detector. It can be used in the form of powder, crystals, pellets or agglomerates for example. The first compartment has enough volume to contain enough desiccant to be able to absorb any moisture that may have entered the watch.

Preferably, at least certain parts 21, visible in FIG. 2, of the capsule in contact with the desiccant product are made of titanium. This metal has the advantage of withstanding corrosion well due to the desiccant product and its use is well mastered in watchmaking.

According to the invention, the capsule comprises a second compartment 28 functioning as an airlock. Referring to Figure 2, the first compartment 27 and the second compartment 28 are separated by an internal wall 22 composed of a membrane 23 and a washer 24 pierced with an opening 25. The internal wall 22 constitutes one of the faces the first and second compartments. Conclusive tests were carried out with a wall with a diameter of 1.8 millimeters and a diameter of the opening with 0.5 millimeters. The washer 24 makes it possible to prevent tearing of the membrane when the desiccant product expands during the absorption of moisture. In an alternative embodiment not shown, this could be dispensed with. washer, for example using a desiccant with lower expansion. The internal wall would then only consist of a membrane. The membrane may for example be of the semi-permeable type or else be produced using a porous filter, as is usual in the chemical industry. Alternatively, the membrane may also be a ceramic membrane, or any other membrane or filter capable of allowing moisture to pass through while retaining the desiccant. The second compartment is also preferably made of titanium.

The second compartment 28 is connected with the interior 32 of the watch by a second opening 26 through a second wall 31, constituting another face of the second compartment. In this variant, the second opening has a relatively small diameter compared to the size of the second wall, preferably less than one millimeter. The second opening is preferably circular, but it could just as easily have any other shape. In this first embodiment, the second wall 31 is substantially parallel to the first wall 22 and the two openings are substantially aligned.

The desiccant is visible from the outside 33 of the watch case through a transparent wall 29 made for example from sapphire crystal. A sealing joint 35 seals around the glass. In this example, the transparent wall is substantially parallel to the first wall 22 and to the second wall 31. Through this transparent wall, the user of the watch can observe the possible changes in color of the desiccant product and therefore detect whether any moisture has entered the watch case.

According to the invention, the capsule is removable and the first compartment can be separated from the second. The first compartment is then replaceable and can be replaced, for example, when a change in the color of the desiccant has been detected. To do this, at least part of the outside of the capsule is provided with a thread 36. The first compartment is therefore screwed into the middle part. A circular seal 34 seals above the thread. The second compartment 28 is integral with the middle part and cannot be replaced. In a variant not shown, the capsule is not removable and the second compartment is integral with the first. In this case, the entire capsule can be replaced, which allows remove traces of desiccant which may still be in the second compartment. The first compartment, or in the variant the entire capsule, can either be replaced by a new one, or be recycled by cooking which allows the water absorbed by the CuS0 _{4 to be} evacuated.

Figure 3 shows another view of the capsule from the outside. A groove 37 is provided to allow the replacement, using a screwdriver, of the first compartment 27 in the first embodiment, or of the entire capsule in the variant. This construction makes it possible to produce a capsule which completely penetrates into the opening of the case, so that the head of the capsule reaches just flush or slightly set back from the surface of the case. Other arrangements for the easy replacement of all or part of the capsule, which can be fixed to the middle part other than by screwing, are within the reach of those skilled in the art.

The invention thus makes it easy to replace the desiccation capsule without opening the watch case. This operation can therefore be carried out very simply even by an inexperienced user, and without risk of damaging the watch seals.

The operation of the article will now be explained.

The humidity inside the watch enters the second compartment of the capsule through the opening 26 of small diameter. Due to the adhesion forces that attract water molecules to the metal of the capsule, a film of water is formed which clings to the walls of the opening and completely blocks it. This film thus forms a liquid wall stretched through the opening 26. The atmospheric pressure in the second compartment repels and maintains this film towards the opening.

Water in liquid form is therefore prevented from entering the capsule. The water which soaks the semi-permeable membrane 22, which may contain traces of desiccant, is separated from the humidity inside the watch case or the article by the volume of air contained in the second compartment. . In the capsules of the prior art, which were not provided with this airlock, this water could spread inside the case and the desiccant dispersed throughout the watch.

The transfer of water through the second compartment takes place by transport of gaseous particles only. These particles come from the evaporation of the film of water stretched through the opening 26. Evaporation is facilitated on the one hand by the body heat provided by the wearer of the watch, and on the other hand by the attraction of the desiccant which absorbs the gaseous particles which have passed through the membrane 23, tending to dry the atmosphere in the second compartment and thus to favor the passage of the water particles from the film from the liquid phase to the gaseous phase.

The film remains stretched through the opening 26 as long as it is supplied with water from inside the watch.

It should be noted that the second opening 26 could have a shape other than circular, for example square or polygonal. The same goes for the second compartment.

Figure 4 shows another embodiment of the desiccation capsule. In this embodiment, the axis of the second opening 26 which connects the second compartment 28 with the interior 32 of the watch is substantially perpendicular to the axis of the first opening 25. With respect to the first embodiment, this allows miniaturization of the capsule in the case of a smaller size. In this embodiment, the second compartment is not replaceable.

In another embodiment not shown in the figures, the product is visible from the outside through a transparent wall which is not parallel to the first wall 22. In this case, at least part of the side walls of the capsule, made of sapphire crystal, is visible from the outside of the watch.

The capsule could be integrated into other parts of the middle than the one shown, or even at the bottom or the dial of the watch. It is of course also possible to integrate a desiccation capsule of one of the types described in articles other than watches, possibly by adapting the volume of desiccant and therefore the dimensions of the capsule to the internal volume of the article. to protect.

FIG. 5 describes another alternative embodiment of a desiccation capsule according to the invention. This variant is more particularly suitable for articles to be protected with greater internal volume. The dimensions of the capsule are therefore much larger, for example of the order of 12mm in diameter and 25mm in length. The first compartment 27 is thus able to contain a larger quantity of desiccant product 30, capable of absorbing the moisture which may have penetrated into an article of larger volume than a watch.

The capsule 20 is preferably made of synthetic or composite material, for example polyacetal. However, it could also be made of metal, preferably titanium in order to resist corrosion due to the desiccant.

The second compartment 28 is separated from the first by an internal wall 22 consisting of a membrane 23 and a flat seal 24, pierced with a first opening 25. A driven bush 40 keeps this wall 22 in place. In order to facilitate disassembly and replacement of the desiccant 30 or of the membrane 23, the sleeve 40 could also be screwed rather than driven into the second compartment 28.

The second opening 26 through the sleeve 40 makes it possible to connect the second compartment 28 with the interior 32 of the article to be protected from moisture. In FIG. 5, this opening is obstructed by a plug 41, which is removed after the capsule has been put in place, as will be seen below. As in the embodiments corresponding to the preceding figures, humidity therefore passes through the second opening 26, then the second compartment 28, before crossing the first opening 25 and the membrane 23 to be absorbed by the desiccant product 30 in the first compartment 27.

The dimensions of the capsule 20 are in this example much larger than in the previous examples. The first opening 25 therefore also has a larger diameter. The capsule 20 is thus adapted to articles of larger volume than that of a watch, for example for camera bodies. The casing of this type of item is generally not waterproof and must be kept away from moisture. In case of complete immersion of the article, it is generally irreparably damaged, regardless of the presence or not of a desiccation capsule.

The desiccant capsule 20 is however useful in this type of article to reduce the humidity of the air inside the housing 11, in order to prolong its duration. The humidity levels that the capsule must absorb are therefore generally low, at least in comparison with the humidity level that can prevail in a watch immersed in water with faulty seals.

Since the semi-permeable membrane 23 has a large surface area, and the moisture content to be absorbed is usually low, it is therefore unlikely that the semi-permeable membrane 23 will completely soak up water, and that desiccant may pass through the membrane and spread inside the device. It is therefore usually not necessary for the second opening 26 to have a small diameter as in the previous embodiments. The side walls of the second compartment 28 however make it possible to collect priority traces of desiccant which accidentally could still cross the membrane.

In the example illustrated, this second opening 26 has a relatively large diameter, equal to the diameter of the first opening 25 and the second compartment 28.

The desiccation capsule 20 can be fixed to the housing 10 of the article to be protected from moisture by non-permanent fixing means, for example by means of a thread 36 corresponding to a thread in an opening in the housing. The capsule can thus easily be unscrewed and replaced when the user detects through the transparent wall 29 a change in color and / or appearance of the desiccant product 30. The capsule can be unscrewed as above using a screwdriver engaged in a groove on the head of the capsule, or manually by taking advantage of a striated surface on the periphery of the head. In a variant particularly suitable for a capsule made of plastic, the capsule can be fixed to the housing by known clip-type means, taking advantage of the elasticity of the material. A peripheral seal is not necessary in the case where this type of capsule is used with articles whose casing is in any case not waterproof, for example conventional cameras. According to material of the case of the article to be protected, for example if it is made of cardboard or soft plastic, the capsule can also be pressed directly by force, possibly through a pre-cut opening. The capsule can be removed and exchanged without opening the case.

The window 29, constituting the transparent wall through which the user can observe the desiccant 30, is made of mineral ice or possibly of Plexiglas, which can then be fixed in the capsule directly by driving it out. A seal 35 protects the desiccant 30 from moisture outside the article housing.

The desiccation capsule 20 is fitted with a stopper 41 before it is placed in the case of the article to be protected. This stopper makes it possible to prevent the desiccant from absorbing moisture, and thus does not arrive to saturation before installing the desiccation capsule. This stopper is preferably made of synthetic material, for example NBR or nitril, but could also be a cork stopper. Thanks to this plug, which is inserted into the opening 26, it is possible to store, transport and market the drying capsule independently of the article to be protected. It is also possible to adapt a plug, of much smaller diameter, in the opening 26 of the desiccation capsules of the previous embodiments.

The article to be protected from humidity can, as we have seen, vary greatly in its construction and in its usefulness, but generally has a housing 11 defining the inside and the outside of the article. This case can, depending on the case, be completely waterproof or offer only limited protection against, for example, splashes or splashes of liquid. The interior of the housing, which contains for example an electronic, mechanical or optical mechanism, is thus more or less protected from humidity. An opening is provided in the housing 11 of the article, adapted to detachably fix therein a desiccation capsule 20. The opening is provided with a thread in the case of a capsule which is screwed. The diameter of the opening must be sufficient to introduce therein a desiccation capsule adapted to the internal volume of the article to be protected, and to allow to clearly see the color changes of the desiccant product through the transparent wall 29 which must therefore have sufficient diameter. If, unlike the case of Figures 1 to 4, the desiccation capsule 20 can not be entirely contained in the volume of the opening, a certain space must be reserved inside the housing 11 to introduce the capsule. The opening is provided in a location on the housing allowing the user to easily check whether the desiccation capsule needs to be replaced, and if necessary to extract it completely to replace or regenerate it, using a screwdriver if necessary. If the article to be protected has a sealed housing allowing immersion, the opening for the capsule may then include a seal, or at least a groove or a location for placing a seal.

The article to be protected is preferably designed so that the transparent wall 29 of the drying capsule 20 placed is visible from the outside. Preferably, this transparent wall arrives flush with the surface of the housing when the capsule is in place, as in FIGS. 1 to 4. In certain types of articles, however, this transparent wall may only be visible by opening the article housing, or through a window in the article housing. If the article is an optical device, for example a camera, a camcorder or a pair of binoculars, the capsule can also be placed inside the housing so that the transparent wall 29 is visible only through the viewfinder of the device, in the form of an alarm signal indicating to the user the need to replace the desiccation capsule.

Claims (12)

Desiccation capsule (20) comprising: - a first compartment (27) intended to contain a desiccant product (30) capable of absorbing moisture, said first compartment being provided on a first face (22) with a first opening (25), - a membrane (23) allowing moisture to pass through but retaining the undissolved desiccant closing off said opening, characterized in that the capsule also comprises a second compartment (28) connected to the first compartment by the first opening (25), said second compartment comprising on a second face (31) a second opening (26), said first compartment is closed on at least one of its faces by a transparent wall (29) making it possible to see the color and / or the appearance of the desiccant product contained in the first compartment, - And in that the capsule comprises non-permanent fixing means (36), making it possible to fix it removably to an article to be protected from humidity. Drying capsule according to the preceding claim, characterized in that the non-permanent fixing means (36) consist of a thread on the periphery of the drying capsule. Drying capsule according to claim 1, characterized in that the non-permanent fixing means (36) are of the clip fixing type. Desiccant capsule according to one of the preceding claims, characterized in that it comprises a peripheral seal (34) preventing water from entering the device to be protected from humidity. Drying capsule according to the preceding claim, characterized in that the second opening (26) is of relatively small size compared to the size of the second face. Drying capsule according to the preceding claim, characterized in that the diameter of the second opening (26) is less than 1mm. Drying capsule according to one of Claims 4 to 6, characterized in that the first compartment is removable and can be separated from the rest of the capsule. Desiccant capsule according to one of the preceding claims, characterized in that it is provided with a removable cap preventing external moisture from reaching the desiccant (30) contained in the first compartment (27). Article comprising a housing (11) defining the interior (32) and the exterior of the article, characterized in that it comprises at least one opening adapted to removably fix therein a desiccation capsule (20) according to the 'one of the preceding claims so that said first opening (25) of the desiccant capsule is inside the article. Article according to the preceding claim, characterized in that it constitutes an electronic, mechanical or optical device. Article according to one of claims 10 or 11, characterized in that said opening is an opening through the housing (11), adapted so that a desiccation capsule can be removably attached thereto with said first opening (25) of the drying capsule located inside the housing and said transparent wall (29) located outside the housing. Use of a desiccant capsule according to one of claims 1 to 7 to protect the interior of an article comprising a housing (11) defining the interior (32) and the exterior of the article.

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