GB1566690A - Timepiece having an alkaline battery - Google Patents

Description

(54) TIMEPIECE HAVING AN ALKALINE BATTERY (71) We, KABUSHIKI KAISHA SUWA SEIKOSHA, a Japanese Body Corporate of 3-4, Scheme, Ginza, Chuo-ku, Tokyo, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a timepiece having an alkaline battery.

Attempts have been made to deal with the leakage of electrolyte from an alkaline battery, but these attempts have not yet been com pletely successful. Although progress is being made in miniaturising electrical apparatus using such a battery, miniaturisation is made difficult by the need to provide a suitable compartment for the battery. Moreover, in many cases the battery has been in direct contact with electrical circuits of the apparatus, so that if electrolyte escapes from the battery, there will not only be damage to the battery itself but also to the apparatus, e.g. a timepiece, as a whole.

Such electrolyte leakages have occurred from both electrochemical and nonelectrochemical factors. Non-electrochemical factors have included the leakage of electro lyte due to an incompletely closed electrolytic cell, cracks in the battery separator, and other physical factors, and such factors have affected both electrodes of the battery. How ever, considerable progress has been made in dealing with such non-electrochemical factors so that these no longer constitute a major problem.

The electrochemical factors, however, remain a serious problem. Thus electrolyte leakage occurs as a result of the fact that the electrolyte creeps up an anode conductive surface adjacent to a sealing member of the battery, while in a conventional battery, the oxygen surrounding the battery inevitably passes into the battery through the packing thereof. Such loss of electrolyte cannot be 'avoided at the present time since one cannot completely remove the gap between the anode cup member of the battery and the packing, although it is desirable to eliminate such a gap in order to prevent the infiltration of oxygen.

Moreover, even if the gap could be completely removed, a surface of the cup-shaped member would be chemically attacked by reason of the presence there of both electrolyte and oxygen. It is therefore desirable to ensure that there is no oxygen in contact with the battery because, if oxygen can be eliminated, the rate of chemical attack will be extremely slow and the electrolyte leakage will be far superior to to that of a conventional battery.

According to the present invention, there is provided a timepiece having an alkaline battery disposed within an inert gas atmosphere which is sealed in the timepiece case.

Thus the battery will not be in contact with an external oxygen-containing atmosphere and consequently the problems discussed above will be reduced, while any metal surface of the timepiece contacted by the said inert gas atmosphere will be protected thereby from oxidation.

Preferably the atmosphere contains one or more of the gases nitrogen, helium, neon, argon, krypton or xenon.

The battery may contain an electrolyte into which an inert gas has been introduced.

The battery is preferably a silver oxide or nickel-cadium battery.

The invention also comprises a method of making a timepiece comprising keeping both a timepiece adapted to be powered by an alkaline battery, and an alkaline battery, in an enclosure containing an inert gas atmosphere for a predetermined length of time, introducing the battery into the case of the timepiece while both are in the enclosure, and sealing the battery in the case so that the battery is disposed in a sealed inert gas atmosphere.

Preferably, an inert gas, or a mixture of inert gases, is caused to flow through the enclosure while both the timepiece and the battery are disposed therein.

Preferably both the timepiece and the battery are kept in the enclosure for at least one hour before the battery is introduced into the timepiece.

The battery may contain an electrolyte into which an inert gas has been bubbled.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which: Figure 1 is a cross-sectional view of an alkaline battery for use in a timepiece acording to the present invention, and Figure 2 is a plan view of a timepiece according to the present invention provided with the battery of Figure 1.

Terms such as "upper" and "lower", as used in the description below, are to be understood to refer to directions as seen in the accompanying drawings.

In Figure 2 there is shown an electronic timepiece constituted by a wrist watch 10 having a watch case 8 provided with a watch glass 8a through which may be viewed a digital time display 9.

Disposed within the watch case 8 is an alkaline battery 11 (Figure 1), the battery 11 being disposed within an inert gas atmosphere which is sealed within the watch case 8. The inert gas atmosphere contains substantially no oxygen and is made up of one or more of the gases nitrogen, helium, neon, argon, krypton or xenon.

The battery 11 comprises cup-shaped members 3, 6 which respectively constitute the anode and the cathode of the battery.

The cup-shaped member 3 is disposed within the upper portion of the cup-shaped member 6 and is sealed thereto by the provision therebetween of an annular packing 1. Anode active material 2 is disposed within the cupshaped member 3, and cathode active material 7 is disposed within the cup-shaped member 6.

Mounted within the cup-shaped member 6 and disposed between the cathode active material 7 and the anode active material 2 is a separator 4 having protective coatings 5 on its upper and lower surfaces.

Example 1.

A battery as shown in Figure 1 was formed by employing a drill-press to punch out two nickel sheet metal cup-shaped members 3, 6 having a thickness of 0.25mm. The cupshaped member 3 was plated with copper to a thickness of 20p and the anode active material 2, which was constituted by a zinc amalgam containing 5% of mercury (Hg) and a zinc powder of 99.99 % purity and 100 mesh particle size, was placed in the cup-shaped member 3 so that the amalgam contacted the latter. The anode active material 2 was then impregnated with an electrolyte such as sodium polyacrylate dissolved in a 30% aqueous sodium hydroxide (NaOH) solution.

The cathode active material 7, which was constituted by a powder containing 3 % carbon and 5% manganese dioxide added to a silver oxide (Ag2O) powder, was introduced into the cup-shaped member 6 and was then impregnated with the electrolyte.

The separator 4, with its protective coatings 5, was then placed on top of the cathode active material 7, and the cup-shaped member 3, with its anode active material 2, was introduced into the cup-shaped member 6, the packing 1 being interposed between the cup-shaped members 3, 6 so as to seal the latter together. The cup-shaped members 3, 6 were then deformed to the shape shown in Figure 1.

Next, a timepiece and the so-finished battery were put in a "glove" compartment through which nitrogen gas was flowing.

After leaving the timpiece and the battery in the "glove" compartment for one hour, the battery was introduced into the case of the timepiece while they were both in the "glove" compartment. The battery was then sealed in the said case so that the battery was disposed in a sealed nitrogen atmosphere.

Example 2.

The battery was made in substantially the same manner as in Example 1, except that the cup-shaped member 3 was made of copper clad metal instead of being plated with copper and the inert gas employed was argon gas instead of nitrogen gas. Moreover, in this case, the electrolyte was introduced into the battery in vacuo, and was saturated with argon gas by bubbling the latter into the electrolyte after any other gas therein had been completely discharged therefrom.

A battery so made has a performance which is twice as good as that of a conventional battery in respect of electrolyte leakage.

Example 3.

The battery was made in substantially the same manner as in Example 2, except that the inert gas employed, both externally of the battery and in the electrolyte, was helium, neon, krypton, xenon, or a mixture of any of these gases.

The battery performance is substantially the same as that of Example 2.

Example 4.

The battery was made in substantially the same manner as in any of the preceding Examples except that a nickel-cadmium battery was made instead of a silver oxide battery. The resulting battery performance is good.

In all the Examples mentioned above, the parts of the timepiece contacted by the inert gas atmosphere are protected from oxidation by reason of the fact that the inert gas atmosphere contains substantially no oxygen.

Consequently, the performance not only of the battery but also of the timepiece itself is improved.

Although only silver oxide and nickelcadmium batteries are referred to in the Examples, any other alkaline battery may be used which can be employed in a timepiece.

WHAT WE CLAIM IS: 1. A timepiece having an alkaline battery disposed within an inert gas atmosphere which is sealed in the timepiece case.

2. A timpiece as claimed in claim 1 in which the atmosphere contains one or more of the gases nitrogen, helium, neon, argon, krypton or xenon.

3. A timpiece as claimed in claim 1 or 2 in which the battery contains an electrolyte into which an inert gas has been introduced.

4. A timepiece as claimed in any preceding claim in which the battery is a silver oxide or nickel-cadmium battery.

5. A timepiece substantially as hereinbefore described with reference to any of the Examples.

6. A method of making a timepiece comprising keeping both a timepiece adapted to be powered by an alkaline battery, and an alkaline battery, in an enclosure containing an inert gas atmosphere for a predetermined length of time, introducing the battery into the case of the timepiece while both are in the enclosure, and sealing the battery in the case so that the battery is disposed in a sealed inert gas atmosphere.

7. A method as claimed in claim 6 in which an inert gas, or a mixture of inert gases, is caused to flow through the enclosure while both the timepiece and the battery are disposed therein.

8. A method as claimed in claim 6 or 7 in which both the timepiece and the battery are kept in the enclosure for at least one hour before the battery is introduced into the time piece.

9. A method as claimed in any of claims 6 to 8 in which the battery contains an electrolyte into which an inert gas has been bubbled.

10. A method of making a timepiece substantially as hereinbefore described with reference to any of the Examples.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. Examples, any other alkaline battery may be used which can be employed in a timepiece. WHAT WE CLAIM IS:

1. A timepiece having an alkaline battery disposed within an inert gas atmosphere which is sealed in the timepiece case.

2. A timpiece as claimed in claim 1 in which the atmosphere contains one or more of the gases nitrogen, helium, neon, argon, krypton or xenon.

3. A timpiece as claimed in claim 1 or 2 in which the battery contains an electrolyte into which an inert gas has been introduced.

4. A timepiece as claimed in any preceding claim in which the battery is a silver oxide or nickel-cadmium battery.

5. A timepiece substantially as hereinbefore described with reference to any of the Examples.

6. A method of making a timepiece comprising keeping both a timepiece adapted to be powered by an alkaline battery, and an alkaline battery, in an enclosure containing an inert gas atmosphere for a predetermined length of time, introducing the battery into the case of the timepiece while both are in the enclosure, and sealing the battery in the case so that the battery is disposed in a sealed inert gas atmosphere.

7. A method as claimed in claim 6 in which an inert gas, or a mixture of inert gases, is caused to flow through the enclosure while both the timepiece and the battery are disposed therein.

8. A method as claimed in claim 6 or 7 in which both the timepiece and the battery are kept in the enclosure for at least one hour before the battery is introduced into the time piece.

9. A method as claimed in any of claims 6 to 8 in which the battery contains an electrolyte into which an inert gas has been bubbled.

10. A method of making a timepiece substantially as hereinbefore described with reference to any of the Examples.