GB1568475A

GB1568475A - Electronic wrist watch

Info

Publication number: GB1568475A
Application number: GB928578A
Authority: GB
Original assignee: Citizen Watch Co Ltd
Current assignee: Citizen Watch Co Ltd
Priority date: 1977-03-08
Filing date: 1978-03-08
Publication date: 1980-05-29
Also published as: JPS53110563A

Description

(54) ELECTRONIC WRIST WATCH (71) We, CITIZEN WATCH COM PANY LIMITED, a Japanese corporate body of 2-1-1, Nishishinjuku, Shinjuku-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 structural assembly of a wrist watch including an electric battery or cell.

In recent years, with the remarkable advancement of electronic technology in the field of watches and clocks, it has been possible to produce parts such as a crystal oscillator, a transducer and a circuit useful in an electronic wrist watch having satisfactorily small sizes, but it has not yet been possible to produce a battery of cell, which is used as the power source for these watches, having a sufficiently small size.

When the watch module or movement of such an electronic wrist watch is considered, the battery or cell is mounted on the watch module or movement protruding therefrom as seen in elevational cross-section and the thickness of the watch movement at the location where the cell is mounted has determined the necessary thickness of the watch module or movement at the present time and the increase of the watch thickness by the battery cell has imposed some limitation to the manufacture of electronic wrist watches having watch cases with a desired small thickness.

On the other hand, in an electronic wrist watch employing a battery or cell, the replacement of the battery or cell has been performed by removing the back cover of the watch or by providing a separate cell cover for the replacement of the battery cell on the back cover and removing the battery or cell cover as necessary. However, the former system, that is, the replacement of the battery or cell by removing the back cover of the watch requires a special tool for the purpose and is a rather troublesome operation. Thus, the replacement of the battery cell by the user is difficult. The latter system, that is, the replacement of the cell by the provision of a cell cover on the back cover is shown in Figure 1 of the accompanying drawings which is a cross-sectional view of a conventional electronic wrist watch.As seen from this Figure, a battery or cell 2 is mounted on a watch module or movement 1 and projects therefrom and a cell cover 4 is connected to a back cover 3 of the watch by means of a bayonet mechanism at the position corresponding to the position of the cell 2. In this arrangement, the center of the cell cover 4 is provided with a coin insertion groove 4a, in the form of a slot in superposed relationship to the battery or cell 2 as seen in plan.

Therefore, the replacement of the battery or cell 2 can be simply performed by inserting a coin possessed by the watch user into the groove 4a and turning the cell cover 4 in the removing direction whereby the battery or cell 2 is accessible for replacement. However, the coin insertion groove 4a formed on the cell cover 4 is required to have a depth ti of at least 700 Fm for engagement with the coin for manipulation of the cell cover and the rest of the cell cover 4, at the position of the groove, is required to have a thickness t2 of at least 500 Fm to provide adequate mechanical strength.

Therefore, as is clear from Figure 1, in the conventional electronic wrist watch in which the cell cover 4 and the battery or cell 2 projecting from the watch module or movement 1 are superimposed one upon the other. the overall thickness of the outer case of the watch tends to be increased to thereby make it difficult to obtain a thin wrist watch.

With the above-mentioned drawbacks of the conventional electronic wrist watch in mind, the present invention has as its object to provide a wrist watch in which it is easy to replace an electric cell or battery and which has a small thickness.

In accordance with the invention there is provided a structural assembly of a wrist watch comprising: a) an outer case of the wrist watch; b) a watch module or movement received in the outer case; c) an electric battery or cell received at least in part by said module or movement; and d) a back cover of the wrist watch attachable to the outer case by a bayonet or other releasable mechanism operable by rotation of the back cover through a limited angle on the outer case, the back cover having a groove for receiving a coin or tool to enable it to be rotated, said assembly being so constructed and arranged that said groove is outside the space taken up by the battery or cell, when the assembly is viewed in plan, both in the attached position of the back cover on the outer case and in the position occupied by the cover when it is rotated from its attached position to a position in which it can be detached from the case the battery or cell being readily replaceable when the cover has been so detached.

Embodiments of the invention are hereinafter described, by way of example, with reference to Figures 2 to 6 of the accompanying drawings, in which: Figure 2 is a cross-sectional view of one embodiment of electronic wrist watch of the present invention; Figure 3 is a cross-sectional view taken in a plane along the coin insertion groove of Figure 2; Figure 4 is a plan view, to a smaller scale, of the back cover of the watch of Figures 2 and 3; and Figure 5 and 6 are plan views showing other embodiments of a back cover of a watch assembly according to the invention.

Referring now to Figures 2 and 3, reference numeral 5 denotes a watch glass, 6 denotes a bezel and 7 denotes an outer wrist watch case. The outer case 7 and bezel 6 are press-fitted together with an 0-ring 8 of L-shaped cross-section interposed therebetween and the shoulder 8a on the O-ring 8 and the shoulder 7a on the outer case 7 are designed to abut against each other. Thus, when the bezel 6 is removed, the 0-ring 8 is held in position on the outer case 7 whereby the O-ring is prevented from falling off and thus the possibility of breakage of the O-rong 8 is reduced when the bezel is removed and re-mounted.The O-ring 8 can stand against repeated mounting and demounting of the bezel as many as ten or so times. 9 denotes a watch module or movement on which a battery or cell 10 is mounted so as to project therefrom whereby the maximum thickness of the watch module or movement 9 is determined by the thickness at the location of the movement 9 where the battery or cell 10 is mounted, similarly as in the instance of the conventional electronic wrist watch shown in Figure 1. 11 denotes a back cover having a groove 11a for the insertion of a coin and a bayonet mechanism which consists of pawls 1 1b provided on the periphery of the back cover in three or four positions spaced around the cover periphery.The pawls 11b are passed through corresponding noches 7b formed in a shoulder 7c provided on the outer case 7 and when the back cover 11 is rotated the pawls 11b leave the noches 7b and engage behind the shoulder 7c to hold the back cover 11 on the outer case 7. A packing 12 is held under compression between the outer case 7 and back cover 11 to thereby provide a water-tight seal. 13 denotes an inner frame or ring having hooks 13a engaging the watch module or movement 9 and hooks 13b engaging the undersurface of the shoulder 7c whereby the inner frame or ring holds the watch module or movement in the outer case 7.The undersurface of the inner frame or ring 13 is provided with notches 13c receiving the pawls 11b, the number of the notches corresponding to the number of the pawls and each notch extending through an angular distance of 45" when viewing the watch in plan. As is more clearly shown in Figures 2 and 4, the cell 10 projecting from the watch movement 9 and the groove 11a in the back cover 11 are so disposed that when the back cover 11 is rotated through an angular distance of less than 45" from the position A to the position B of the groove 11a, the pawls 11b are brought into alignment with the notches 7b and the cover 11 may be removed. It will be understood that an angular rotation of over 90 would be difficult from the point of view of design.

The rotation locus C described by the back cover does not interfere with the battery cell 10 as is apparent from Figure 4, that is, the coin insertion groove 11a remains in an eccentric position on the back cover 11 with respect to the battery or cell 10 for engagement by the usual removal tool such as a coin. Thus, the invention avoids a superimposed relationship of the battery or cell and the coin insertion groove, which relationship determines the maximum and substantial thickness of the prior art wrist watches.

By way of example, assuming that the thickness t3 of the back cover 11 is 500Fm and the depth t4 of the coin insertion groove 11a is 700 Rm, as seen from Figure 2, the total thickness of the outer case is reduced, in comparison with the prior art, by the depth t4 of the coin insertion groove gila. In addition, since the back cover 11 and outer case 7 are connected together by means of the bayonet mechanism which has a rotation angle of less than 45 , the back cover 11 can be easily mounted and removed and the battery or cell 10 and coin insertion groove 1 lea can be readily disposed in an offset relationship.Since the present invention eliminates the cell cover 4 as employed in the conventional electronic wrist watch of Figure 1, the desirable slant faces D, E of the outer case 7 and back cover 11, respectively, can be easily provided.

In the modification of the back cover 14 of the watch shown on Figure 5, a groove 14a for the insertion of a coin or other cover removal tool is open at both ends adjacent the cover periphery. In the modification of the back cover 14 of the watch shown in Figure 5, a groove 14a for the insertion of a coin or other cover removal tool is open at both ends adjacent the cover periphery. In the modification of the back cover 15 shown in Figure 6, a groove 15a for a coin or other tool is open at one end adjacent the cover periphery and terminates at its other end adjacent the cell 10.In each of the modified embodiments of the cover of Figures 5 and 6 the coin insertion groove is arranged not to overlap the cell 10 and has substantially the same practical effect as the groove ila of Figure 4 with respect to the engagement with the user's detachment tool such as a coin.

It will be noticed that in the embodiments of the back cover shown in Figures 4 and 5 the grooves 11a and 14a are, respectively, tangential to and parallel to a plane tangen tial to, the side surface of the battery or cell 10; also, the grooves ila and 14a are both eccentric to the centre axis of the back cover. In the embodiment of the back cover shown in Figure 6 the groove 15a extends in the direction of a diameter of the back cover.

With the above-mentioned construction and arrangement of the parts of the electro nic wrist watch, since the back cover and outer case are directly connected together by means of the bayonet mechanism to hold the back cover on the outer case, the rotation angle of the back cover is limited by the bayonet mechanism, and thus it is made possible for the cell and the coin insertion groove in the back cover to be arranged in an offset relationship. By this means the overall thickness of the outer case is re duced; also, the back cover can be easily removed by means of a coin or the like.

Furthermore, since the back cover can be easily removed, one side of the watch module or movement can be exposed and the cell replacement can be easily per formed regardless of the method of retaining the watch module or movement. Finally, since a separate cell cover, in addition to the back cover of the watch, is not necessary, the wrist watch of the invention has great advantages with respect to production cost reduction.

Obviously it is not essential to use a bayonet mechanism for attachment of the back cover to the outer case but other releasable mechanisms, e.g. a screw mechanism, operable by rotation of the back cover through a limited angle on the outer case, may be employed.

WHAT WE CLAIM IS: 1. A structural assembly of a wrist watch comprising: a) an outer case of the wrist watch; b) a watch module or movement received in the outer case; c) an electric battery or cell recieved at least in part by said module or movement; and d) a back cover of the wrist watch attachable to the outer case by a bayonet or other releasable mechanism operable by rotation of the back cover through a limited angle on the outer case, the back cover having a groove for receiving a coin or tool to enable it to be rotated, said assembly being so constructed and arranged that said groove is outside the space taken up by the battery or cell, when the assembly is viewed in plan, both in the attached position of the back cover on the outer case and in the position occupied by the cover when it is rotated from its attached position to a position in which it can be detached from the case, the battery or cell being readily replaceable when the cover has been so detached.

2. An assembly, according to Claim 1, wherein said limited angle is less than 90".

3. An assembly, according to Claim 2, wherein said limited angle is less than 45 .

4. An assembly, according to any preceding Claim, wherein said groove is tangential to or is parallel to a plane tangential to. a surface of the battery or cell when the back cover is assembled with the outer case and the assembly is viewed in plan.

5. An assembly, according to Claim 4, wherein said groove is eccentric to the centre axis of the back cover.

6. An assembly, according to any one of Claims 1 to 3, wherein said groove extends in the direction of a diameter of the back

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

Claims

**WARNING** start of CLMS field may overlap end of DESC **. depth t4 of the coin insertion groove gila. In addition, since the back cover 11 and outer case 7 are connected together by means of the bayonet mechanism which has a rotation angle of less than 45 , the back cover 11 can be easily mounted and removed and the battery or cell 10 and coin insertion groove 1 lea can be readily disposed in an offset relationship. Since the present invention eliminates the cell cover 4 as employed in the conventional electronic wrist watch of Figure 1, the desirable slant faces D, E of the outer case 7 and back cover 11, respectively, can be easily provided. In the modification of the back cover 14 of the watch shown on Figure 5, a groove 14a for the insertion of a coin or other cover removal tool is open at both ends adjacent the cover periphery. In the modification of the back cover 14 of the watch shown in Figure 5, a groove 14a for the insertion of a coin or other cover removal tool is open at both ends adjacent the cover periphery. In the modification of the back cover 15 shown in Figure 6, a groove 15a for a coin or other tool is open at one end adjacent the cover periphery and terminates at its other end adjacent the cell 10.In each of the modified embodiments of the cover of Figures 5 and 6 the coin insertion groove is arranged not to overlap the cell 10 and has substantially the same practical effect as the groove ila of Figure 4 with respect to the engagement with the user's detachment tool such as a coin. It will be noticed that in the embodiments of the back cover shown in Figures 4 and 5 the grooves 11a and 14a are, respectively, tangential to and parallel to a plane tangen tial to, the side surface of the battery or cell 10; also, the grooves ila and 14a are both eccentric to the centre axis of the back cover. In the embodiment of the back cover shown in Figure 6 the groove 15a extends in the direction of a diameter of the back cover. With the above-mentioned construction and arrangement of the parts of the electro nic wrist watch, since the back cover and outer case are directly connected together by means of the bayonet mechanism to hold the back cover on the outer case, the rotation angle of the back cover is limited by the bayonet mechanism, and thus it is made possible for the cell and the coin insertion groove in the back cover to be arranged in an offset relationship. By this means the overall thickness of the outer case is re duced; also, the back cover can be easily removed by means of a coin or the like. Furthermore, since the back cover can be easily removed, one side of the watch module or movement can be exposed and the cell replacement can be easily per formed regardless of the method of retaining the watch module or movement. Finally, since a separate cell cover, in addition to the back cover of the watch, is not necessary, the wrist watch of the invention has great advantages with respect to production cost reduction. Obviously it is not essential to use a bayonet mechanism for attachment of the back cover to the outer case but other releasable mechanisms, e.g. a screw mechanism, operable by rotation of the back cover through a limited angle on the outer case, may be employed. WHAT WE CLAIM IS:

1. A structural assembly of a wrist watch comprising: a) an outer case of the wrist watch; b) a watch module or movement received in the outer case; c) an electric battery or cell recieved at least in part by said module or movement; and d) a back cover of the wrist watch attachable to the outer case by a bayonet or other releasable mechanism operable by rotation of the back cover through a limited angle on the outer case, the back cover having a groove for receiving a coin or tool to enable it to be rotated, said assembly being so constructed and arranged that said groove is outside the space taken up by the battery or cell, when the assembly is viewed in plan, both in the attached position of the back cover on the outer case and in the position occupied by the cover when it is rotated from its attached position to a position in which it can be detached from the case, the battery or cell being readily replaceable when the cover has been so detached.

7. A structural assembly of a wrist watch substantially as hereinbefore described with reference to, and as illustrated in, Figures 2 to 6 of the accompanying drawings.