AU665966B2

AU665966B2 - Method for mounting a crystal on a watch case, timepiece comprising positioning means for a crystal on a case, crystal and case intended for fitting out such a timepiece

Info

Publication number: AU665966B2
Application number: AU30492/92A
Authority: AU
Inventors: Olivier Koch; Yves Meystre
Original assignee: ETA Manufacture Horlogere Suisse SA; Ebauchesfabrik ETA AG
Current assignee: ETA Manufacture Horlogere Suisse SA
Priority date: 1991-12-28
Filing date: 1992-12-24
Publication date: 1996-01-25
Anticipated expiration: 2012-12-24
Also published as: TW223684B; CH683482GA3; JPH05264750A; BR9205175A; CN1078050A; CN1037377C; CA2084953A1; EP0549978A1; EP0549978B1; CH683482B5; AU3049292A; ATE166731T1; KR930013896A; DE69225687D1; MX9207262A

Abstract

The invention relates to a method for fitting a glass onto a watch case, a timepiece comprising means for placing in position a glass on a case, as well as a glass and a case intended to equip such a piece. The timepiece according to the invention includes: - a case (1), - a glass (6) mounted on the case (1), - means for fixing the glass to the case, and - means for angular positioning of this glass on the said case, this piece being characterised in that the means for angular positioning consist, on the one hand, of a notch (14) made directly on the glass (6) and, on the other hand, of a protuberance (22) which is made directly on the case (1) and which is engaged into the said notch (14). The invention applies for example to timepieces including a glass and a case made from heat-weldable thermoplastic material. <IMAGE>

Description

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AUSTRALIA

Patents Act 1990 0% V= I% dft

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ORIGINAL

COMPLETE SPECIFICATION STANDARD PATENT S. S. Application Number: Lodged:

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Invention Title: METHOD POR MOUNTING A CRYSTAL ON A WATCH CASE, TIMEPIECE COMPRISING POSITIONING MEANS FOR A CRYSTAL ON A CASE, CRYSTAL AND CASE INTENDED FOR FITTING OUT SUCH A TIMEPIEC~e The following statement Is a full description of this Invention, Including the best method of performing It known to :-LIS 1

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-2 The present invention concerns a method for mounting a crystal on a watch case with a predetermined relative angular position.

Likewise, it concerns a timepiece comprising positioning means fcr a crystal on a case as well as a crystal and a case intended for fitting out such a timepiece.

More specifically, the invention concerns the mounting and positioning of a crystal of plastic material on a watch :case formed in material of the same type, the crystal being heat welded onto the case by a technique such as ultrasonic welding.

BACKGROUND OF THE INVENTION A welding technique of this type is described in *5 European patent EP 0101663.

Furthermore, mounting systems enabling a predetermined angular positioning of a crystal on a case as well as positioning means for such mounting are already known.

Nevertheless, such systems exhibit a major difficulty in being of complex structure or being visible from outside the watch.

The present invention thus has as its purpose to provide a method for assembling a crystal on a watch case and a timepiece provided with positioning means for such crystal on the case as well as a crystal and a case intended for fitting out such a timepiece without the above-mentioned defaults.

SUMMARY OF THE INVENTION To this effect, the invention has as its objective a method for mounting a crystal on a watch case with a predetermined relative angular position characterized in that it consists: on the one hand, of providing a positioning notch directly in the crystal, on the other hand, of providing a protuberance directly on the case having a form corresponding to that of said notch and which is shaped so as to be engageable therein, then of bringing the crystal onto the case while 9 placing said notch and said protuberance into coincidence 0469 in order to allow their engagement and permit securing the crystal onto the case.

The invention also has as objective a timepiece of the type comprising: a watch case, a crystal mounted on the case, n means fr securing the crystal onto the case, and anigular positioning means for said crystal onto said case, 1 such timepiece being characterized in that said angular positioning moans are made up, on the one hand, of a notch rmovided directly on the crystal and, on the other hand a protuberance which is directly provided on the case and 4hich is engaged in said notch.

Furthermore, the invention has as objective on the one hand a crystal characterized in that it includes a positioning notch made up from a V-shaped qroove which extends radially and which is provided on an edge of said crystal and, on the other hand, a case including a caseband and a back cover characterized in that it further includes 4 a positioning protuberance provided on its caseband, such potuberance having at least a portion in the form of an isosceles triangle exhibiting a summit angle of about Other characteristics and advantages of the invention will appear upon reading the detailed description which follows, formulated with reference to the attached drawings which are given uniquely by way of example.

BRIEF DESCRIPTION OF THE DRAWINGS $p.ece Figure 1 is a partial cross-section of a timepiece assembly including a crystal positioned and mounted on a case by means of a mounting method and positioning ****means according to the invention; figure 2 is a partial cross-section of a crystal alone according to the invention taken in the portion of the crystal shown by arrow I on figure 1; figure 3 is a partial side view of the crystal according to the invention taken according to arrow III of figure 2; figure 4 is a partial top view of a watch case according to the invention; figure 5 is a partial cross-section taken along arrows V-V of figure 4, and figure 6 is a view similar to figure 5, but showing the crystal of figures 2 and 3 positioned on the case of figures 4 and 5, and ready to be heat welded onto such case.

DESCRIPTION OP' THD PREFERRED EMBODIMENT As is seen on figure 1, the timepiece according to the invention comprises a watch case 1 including a caseband 2 and a bezel 4 formed integrally in this example and thus constitLting a single piece assembly.

5 Such timepiece further includes a crystal. 6 which is assembled on case 1 Crystal 6 and case 1 are formed in this example of thermoplastic heat-weldable materials.

Crystal 6 for example is formed of a transparent acrylic resin (PMMA) commonly designated under the trademark "Plexiglas". As to the case, this is formed from one of the materials designated by abbreviations ABS, ASA or SAN.

Such materials correspond respectively to an acrylic butadiene styrene, to an acrylic styrene acrylic ester and to styrene acrylic nitrile. Between crystal 6 and case 1 is interposed a dial 8.

under dial 8 and in case 1 is housed a standard timepiece movement M here shown in a symbolic manner in mixed dashed lines.

JReference henceforth will be had to figures 2 and 3 which represent in a more detailed manner a crystal 6 intended for fitting out a timepiece according to the invention.

Crystal 6 includes a chamfered peripheral edge opening out towards the exterior and intended to be brought into enqi.gement with a circular groove 12 (figures 1 and 4) provided in case 1. Aq has beon described in a more detailed manner in the above-mentioned European patent, 0~ ~edge 10 is intended to be heat welded onto case 1,k in particular by an ultrasonic techoiquo.

it will be noted that crystal 6 includes a positioning notch 14 formed at least in its upper portion by a V-shaped groove which extends radially to crystal 6 and which is provided in edge Such notch 14 exhibtt at least in its upper portion, an isosceles triangle form with a summit angle A (figure 3) having a value chosen to be between 85' and 6 Preferably, angle A has a value of 90*. Notch 14 is thus provided in an outermost radial position on edge 10 and it opens out in a lateral manner exteriorly and interiorly relative to crystal 6.

Henceforth reference will be had to figures 4 and which represent in greater detail a case I intended to fit out a timepiece according to the invention.

Case 1 includes a caseband 2 which is extended by horns 18 enabling securing of a bracelet, not shown, and which Includes a back cover As mentioned hereinabove, case 1 exhibits a channel or circular groove 12 intended to form a weld zone with edge 10 of crystal 6.

According to the invention, case 1 includes a :positioning protuberance 22 provided on such case and in particular, on its caseband 2.

*.:Such protuberance 22 which is formed in the groove or channel 12 has at least partially the form of an isosceles triangle exhibiting a summit angle D (figure of about 8L2.

F~igure 6 represents crystal 6 positioned on case 1 prior to the operation of welding the two elements to one another. it will be noted thus on this figure that protuberance 22 which exhibitso. at least in its upper portion, a beveled form extends towards crystal 6 in a manner normal to Casa 1.

More specifically, it is noted that notch 14 opens out facing case 1.

Thus, it in undoratooa that the m~ounting of the crystal 7 on the case is e-ffected by positioning crystal 6 above case 1, then ir;~>4ng edge 10 into the channel or groove 12. The crystal is rotated in a clockwise or counter-clockwise sene until notch 14 comes into coincidence with protuberane 22 and adjusts itself thereon.

Next, the ultrasonic welding operation is effected through a sonotrode, not shown, as explained in detail in the above-mentioned document BP 0101663.

Figure I represents the assembled timepiece with notch 14 and protuberance 22 forming an amalgamation zone F. It is thus understood that in this state notch 14 and .4O protuberance 22 are welded to one another.

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The amalgamation zone extends in an annular manner over the timepiece since edge 10 is heat welded over its entire periphery to caseband 2 in channel or groove 12.

4 Such amalgamation obtained by welding of the two materials forms means of securing the crystal 6 onto case 1.

Notch 14 and protuberance 22 form positioning means which in this timepiece thus form an integral portion of the previously-mentioned securing means.

4044 The method of mounting according to the invention is as follows.

Initially, one provides, on the one hand, directly in crystal 6 the positioning notch 14 which for example is obtained by moulding with such crystal. More spodifically, one provides such notch in the edge 10 of crystal 6 in shaping such notch 14, at least in its upper portion, in the form of a V which extends in a radial direction relative to crystal 6 and which opens out towards a free extremity r. of the lattnr.

a- On the other hand, one provides directly on case I a protuberance 22 which, as has been explained, is of a form corresponding to the notch 14, namely an isosceles triangle and which is shaped to be able to engage in the latter.

In these steps, notch 14 and protuberance 22 are given their respective angles A and B of 900 and 800 Next, crystal 6 is brought onto a case 1 in placing in coincidence notch 14 and protuberance 22 in order to permit their relative engagement and enable securing of the crystal 6 onto case 1.

Finally, one proceeds with the heat welding in welding 0* SO O the assembly notch 14 and protuberance 22 in a manner simultaneous with the heat welding of the free edge 10 of crystal 6 onto case 1.

@0 6 "'Such method as well as the means of the invention which have just been described have shown themselves after numerous trials to assure a perfect angular positioning of the crystal onto the case, without any of its components being visible from outside the finished timepiece, for example from the top of the crystal. Furthermore, such invention is simple and inexpensive since notch 14 and protubeorance 22 may be formed without additional manufacturing operations, but solely during moulding, for example during *espectiva injection operations of the crystal and the case, Furthermore, the crystal provided with its notch 14 may be adapted onto cases without a protuberance which permits a botte4r adaptability and excellent flexibility of the manufacturing assembly .;cations.

Claims

1. A method for mounting, with a predetermined relative angular position, a crystal on a watch case comprising at least a caseband characterized in that it comprises the steps oft providing a positioning notch (14) directly in an edge (10) of the crystal intended to be secured onto the caseband providing a protuberance (22) directly on the caseband said protuberance having a form corresponding to that of said notch (14) so as to be engageable therein, then bringing the crystal onto the caseband and placing said notch (14) and said protuberance (22) into coincide~nce in order to allow their engagement and permit securing the crystal onto the case

2. A method according to claim 1, characterized in that in step said notch (14) is shaped, at least in its upper portion, in a V form extending in a radial direction relative to the crystal and opening out towards a free extremiity M~ thereof.

3. A method according to claim 2, characterized in that said notch (14) is shaped as an isosceles triangle exhibiting a summnit angle of 900.

4. A method according to claim 3, characterized in that in step said protuberance (22) is shaped, at least in its upper portion, in the form of an isosceles triangle exhibiting a summit angle of 800. S. A method according to anyone of the preceding claim~s, in which the crystal and the caseband are of heat-weldable materials, characterized in that, following step the crystal is heat welded onto the caaaband through its edge which is brought to amalgamate with the material of said caseband, said notch (14) and said protuberanco (22) being likewise heat welded simultaneously with the heat weldingj of the edge of the crystal onto the caseband

6. A timepiece of the type comprising: a watch case having at least a caseband -a crystal mounted on the case means for securing the crystal onto the caseband of the case and angular positioning means for said crystal (6) onto said caseband characterized in that said angular positioning means are made up, on the one hand, of a notch (14) provided directly in an edge (10) of the crystal and, on the other hand ot a protuberance (22) which is directly provided on the caseband of the case and which is engaged in said notch (14),

7. A timepiece according to claim 6, characterized in that said notch (14) is provided in an outermost radial. position of said crystal

8. A timepiece according to claim 6 or 7, characterized in that said notch (14) opens out laterally, exteriorly and interiorly relative to the crystal

9. A timepiece according to one of claims 7 to 9, characterized in that said notch at least in its upper portion, is made up of a V groove extending radially to the crystal and opening out facing the case A timepiece according to claim 9, characterized in that said notch (14) exhibits the form of an isosceles triangle. 11, A timepiece according to claim 10t characterized in that the summit angle of the iiotch (14) is chosen to be between 85' and 0 too 12. A timepiece according to claim 1,j characterized in that the summit angle of the notch (14) is 900.

13. A time~piece according to claims 11 or 12, 4h*6* characterized in that said protuberance (22) exhibits, at. too*: least in its upper portion, the form of an isosceles triangle the summit angle of which is 14, A timepiece according to one of claims 6 to 13, characterized in that the positioning means (14,22) form an integral part of the means for securing the crystal (6) onto the caseband, of the case A timepiece according to claim 14, in which the caseband and the crystal are formed of heat-weldable materials, characterised in that the notch (14) and the protuberance (22) are welded to one another.

16. A crystal intended for fitting our a timepiece, characterised in that it Includes a positioning notch (14) made up of a V groove which extends radially and which is provided on an edge of said crystai

17. A crystal according to claim 16, characterised in that said notch at least in its upper portion, exhibits an isosceles triangle from having a summit angle with a value of

18. A case intended for fitting out a timepiece, and comprising at least a caseband characterised In that it Includes a protuberance (22) provided 'n its caseband for angularly positioning a crystal with respect to the caseband, said protuberance extending radially and having, at least in part, an isosceles triangle form exhibiting a summit angle of

19. A case according to claim 18, in which said caseband is formed of heat- S weldable material, characterised in that said protuberance (22) is formed in a circular groove provided on a caseband, said groove being intended to form a S weld zone, in particular with the edge (10) of a crystal C ATE this 31st day of October, 1995. TA SA E&ABRIQUES D'EBAUCHES WATERMARK PATENT TRADEMARK ATTORNEYS LEVEL 4, AMORY GARDENS .2 CAVILL AVENUE ASHFIELD N.S.W. 2131 AUSTRALIA LJD:RJD:GL DOC 15 AU3049202.WPO a e a, 4. *e *4 METHOD FOR MOUNTING A CRYSTAL ON A WATCH CASE, TIMEPIECE COMPRISING POSITIONING MEANS FOR A CRYSTAL ON A CASE, CRYSTAL AND CASE INTENDED FOR FITTING OUT SUCH A TIMEPIECE a S ABS 'RT OF THE DISCLOSURE The present invention concerns a method for mounting a crystal on a watch case, a timepiece comprising position- ing means for a crystal on a case, as well as a crystal and a case intended for fitting out such a timepiece. The timepiece according to the invention includes: a case a crystal mounted on the case means for securing the crystal onto the case, and angular positioning means for such crystal on said case, such timepiece being charact- erized in that the angular positioning means are made up, on the one hand, by a notch (14) provided lirectly on the crystal and, on the other hand, by a protuberance (22) which is directly provided on the case and which is engaged in said notch the invention is applied for example to timepieces including a crystal and a case of heat-weldable thermoplastic material.