GB2050654A

GB2050654A - Wrist-watch of Reduced Thickness

Info

Publication number: GB2050654A
Application number: GB8013785A
Authority: GB
Original assignee: SSIH Management Services SA
Current assignee: SSIH Management Services SA
Priority date: 1979-04-27
Filing date: 1980-04-25
Publication date: 1981-01-07
Also published as: IT8021565A0; DE3016058C2; CH639812GA3; DE3016058A1; HK49290A; IT1148794B; CH639812B; GB2050654B

Abstract

A construction of an electronic wrist-watch has a greatly reduced overall thickness constituted by the super-position of the case back 1, at least two time indicating discs 4, 5 and the crystal 8. The remaining elements such as the motor 9, oscillator 14, battery 13 and gear train 10 are placed outside the periphery of the discs. The discs carry respective minute and hour hand marks 6, 7 (the minutes disc 5 being transparent) and are pivoted on a stud 3 on the case back 1. To reduce as far as possible the watch thickness while at the same time maintaining rigidity of the discs, they are supported at their peripheries, which are toothed and driven by the gearing, by rollers 18, 33. <IMAGE>

Description

SPECIFICATION Wrist-watch of Reduced Thickness This invention has as its object to provide a wrist-watch of reduced thickness comprising a watch case, a crystal and at least two time indicating discs such discs being coupled together by a gear train itself driven by an electric motor controlled by-an electronic circuit.

A mechanical wrist-watch with the same type of display has been previously known from the prior art. Swiss patent No. 307 045 describes a mechanical wrist-watch in which the barrel drives an hours disc and a minutes disc through the intermediate of the usual motion work. In this form the barrel is coaxially mounted with the indicator discs and the motion work as well as the final train are found at the exterior of the indicating discs and within two diametrically opposed wings arranged between the bracelet attaching lugs.In addition to the fact that the purpose sought in the above-cited patent was not that of obtaining a reduced thickness watch but rather to produce an aspect of mystery in giving to the watch hands the impression of being suspended, it will be appreciated that the space employed by the barrel renders it unsuitable for showing the reduced thickness overall and that only methods employing elements of the most modern techniques may be used to displace the motor element beyond the periphery of the indicating discs. Moreover neither of the Swiss patents Nos. 312 519 and 312 520 which were patents of addition to the above previously mentioned patent suggest solutions to the problems which the present invention proposes to solve.

Other propositions have been made for replacing the hands by indicating discs. The German laid open applications DEOS 22 04 907 and DEOS 25 48 559 each described a clock provided with transparent discs. Figure 1 of the first mentioned shows that no means has been employed to reduce the thickness of the clock, the disc driving system requiring an important amount of space between the discs. In the second of the above-mentioned publications the purpose is to give the impression that the hands are not driven by any mechanism. If this display appears to require little thickness its driving mechanism to the contrary is lodged in a socket having a thickness clearly greater than the clock and forming a support therefor.

Extra flat watch movements have already been proposed. French patent application No. 2 341 886 describes such a movement having manual or automatic winding and for which the thickness does not exceed 1, 5 or 2 mm, and where the moving parts suspended from the bottom plate are pivoted in cantilever. This relatively complex system requires expensive elements, notably ball bearings.

In the classic type of wrist-watch driven however by a quartz controlled osciilator with an electric motor and an analog type display, at least 9 elements are superposed in arriving at the overall thickness of the watch. These are the case back, the bottom plate, the minute wheel, the motion work (dial train), the hour wheel, the dial, the minutes and the hours hands and finally the crystal. It is the purpose of the present invention to reduce as far as possible the number of these elements juxtaposed one over the other in order to obtain a watch of overall reduced thickness. It is another purpose of the present invention to use electronic elements to obtain the most flexible arrangement of said elements with respect to one another in order to be able to reduce greatly the overall thickness of the watch.

The wrist-watch in accordance with the invention is characterized in that the overall thickness is constituted by superposition of the back of the case the time indicating disc and the crystal, there have being sufficient play arranged on all sides of said discs to permit free movement thereof. The remaining priciple watch elements such as the motor, gear train and electronic circuit are located in portions of the case extending beyond the diameter of the indicating discs, said portions having a thickness no greater than the overall thickness.

For a better understanding of the description which is to follow reference is made to the drawings which show by way of example a preferred form of the invention: Figure 1 is a plan view of the watch bottom plate to a greatly enlarged scale, Figure 2 is a cross section of the watch to an enlarged scale the various elements having been arranged in order to render the mechanism more readily understandable and according to a first variant of the invention, Figures 3a and 3b represent a cross section of the gear train as employed to drive the hours indicator as well as the minutes indicator, Figure 4 is a cross section of the watch to an enlarged scale according to a second variant, Figure 5 is a cross section of the watch to an enlarged scale according to a third variant, Figure 6 is a cross section to a still greater scale showing a gear train acting to drive the discs.

Figures 1 and 2 clearly show how the watch is arranged. According to a first form of the invention the watch case comprises a case back 1 and a cover member 2. The case back comprises at the same time the bottom plate of the watch supports all the components either in beds or on studs. Around a first central stud 3 there pivots a metallic hours disc 4 and a transparent minutes indicator disc 5. On each of these discs there is impressed a guide mark which represents repectively the hours hand 7 and minutes hand 6.

The watch cover 2 comprises a crystal 8 through which may appear the discs with guide marks and below which a dial is engraved or impressed. Two diametrically opposed extensions project on either hand of the Indicator discs.

The left extension carries an electric motor 9 and a gear train 10 with gears arranged to pivot on studs 22 and is arranged and adapted to drive the discs 5 and 4 by means of their peripheral teeth 11 and 12.

Since the thickness of these discs will constitute the greater part of the overall thickness of the watch it is of interest to reduce as much as possible such thickness. It should be chosen to between 0,05 and 0,15 mm with a preferred value of about 0,1 mm. The discs are initially cut out in the form of a washer; thereafter peripheral teeth are cut therein. It is important to manufacture such discs from a stable material which exhibits very little deformation because of differences in temperature and humidity.One may use for example transparent plastics material such as mylar (Registered Trade Mark). In this case to avoid static electric charges which attract dust or to avoid deformations the internal surface of the crystal will coated with an antistatic product which may for instance be a semitransparent metallic layer or better still a metallic transparent metal oxyde of the type ITO (Indium Tin Oxyde). One may likewise employ sapphire as a variant material for such discs as shall be explained further on. Since these indicator discs are very thin and particularly should they be executed in a piastic material it is necessary to foresee guide means situated proximate the drive wheels and which will maintain teeth of the drive wheels opposite the teeth of the discs.Such arrangement 18 is shown in figure 1 and 2 and comprises a first roller 30 intended to guide the hours indicator 4 and second roller 31 intended to guide the minutes indicator 5. The roller may be in two independent pieces, are superposed one over the other and may rotate freely about a stud 32 fixed to the case back 1. The arrangement of the guide rollers is such that if the hours indicator 4 is not entirely flat it will be supported on roller 30 to rotate the latter reducing thus the considerable friction loss which would result if the roller were fixed. In the same manner the minutes disc 5 may come into contact with roller 31.

Figure 1 shows a second guide arrangement 33 which may apply to the construction to assure a still better correspondence between the teeth. It will be understood that arrangements 18 and 33 are as shown in figure 1 that is to say proximate the drive wheels and that the arrangement of guide 1 8 of figure 2 does not really correspond to the construction utilized but has been shown thus for purposes of clarity in the drawing.

The right hand extension includes an energy source 13 (battery), a quartz oscillator 14, a trimmer 15, an electronic circuit 1 6 and a corrector 1 7.

As clearly shown in figure 2 the overall thickness of the watch is constituted only by the superposition of four elements, namely the case back 1, the indicator discs 4 and 5 and the crystal 8, whereas in Swiss patent No. 307 045, as previously cited, this thickness comprises at least 6 elements. The same figure 2 shows as well that the extensions containing the various other elements included in the watch and situated beyond the indicator discs comprise a case which does not substantially exceed the overall thickness. It must here be recalled that sufficient play must be arranged on all sides of the indicating discs in order that they may move freely.Although the invention employs a known arrangement for displaying the hours and the minutes, it employs this to a greater profit in order to achieve in connection with the use of modern electronic elements a result until now quite unknown, that is to say, a reduction of great magnitude in the thickness in the watch. The construction disclosed permits effectively to obtain a thickness of the order of 1,5 mm including watch case, such being hitherto unknown.

Figure 3a shows how the hours disc 4 may be driven from pinion 19 as fixed to the axis of motor 9 via the hour wheel 20. Incorporated into the gear train is also to be found a minutes wheel 21 which drives the minutes disc 5 as shown in figure 3b. As previously mentioned the indicator discs are very thin and because of this they are poorly adapted to transmit a torque. In Swiss patent No. 307 045 as already mentioned one may see in figure 3 that the hours disc 15 as driven by the barrel cover 11 drives through teeth 12 the minutes disc 21 by way of a gear train 24 to 28. The construction here proposed avoids the problem wherein one of the indicators is required to transmit its motion to the other indicator, since each of the said indicators are driven by separate and independent gear trains and this from a common driving wheel 21 as shown in figure 3a and 3b.

The single phase bipolar motor which drives the mechanism must exhibit a thickness as small as possible. This is difficult to realize using known motors which have only a single winding in the stator circuit. in order to limit this thickness the invention proposes the utilization of two windings 34, 35 such as shown in figure 1. A still greater reduction may be obtained in a variant of the invention where the number of the windings is increased to 4. In such case each motor pole includes two windings.

It will be understood from examination of figure 2 that the case back may carry the dial. In such case both indicator discs are transparent and may be arranged to bear the hours hand and minutes hand as already explained. It will be equally understood that the invention is not limited to two discs and that the watch may comprise in addition to the hours and minutes disc as previously described further disc indicating seconds.

Figure 4 shows a further variant of the invention. It may be distinguished from preceding variant in figure 2 by the fact that the cover 2 bears a case band 36 around its entire periphery.

Figure 4 shows the case back 1 of the watch which at the same time serves as the bottom plate on which are mounted all the mechanical and electrical components. The bottom plate is introduced into the case 2 which includes a case band 36 which is integral therewith and surrounds it entirely as well as a crystal 8. The purpose of this entire construction being directed to reduction of the thickness of all portions to the extent that such may be possible the case back 1 and the case 2 may not be absolved from this rule. As a consequence there is a weakening of the structure and thereby an excessive vulnerability to shocks and strains which may arise. The case band 36 as described enables an increase in the rigidity to an important extent and provides to this extra flat watch all the reliability that one may expect from an ordinary watch.

Figure 5 shows a third variant of the invention.

The difference between this variant and those which have been shown in figures 2 and 4 resides in that the case back of case 1 includes a second crystal 40 placed opposite the first crystal 8 and which has as its purpose to render the entire watch transparent throughout and give thereto a new and unexpected aesthetic aspect in the sense that it appears to lack any drive mechanism.

In one version of this variant the first and second crystals are formed of mineral glass and discs 4 and 5 of transparent plastic material such as mylar.

Preferably and with the purpose of improving the transparency, the watch crystals and disc are realized in sapphire (Al2O3 monocrystalline). One will equally note that discs formed of this material may be perfectly planar which is not the case with discs formed of plastics material which may be deformed and thus create difficulties in the mechanical functioning of the watch. In addition to its rigidity sapphire may only be scratched with great difficulty which diminishes the difficulties presented during machining and of the handling of the parts in question. In this construction which may include at least 8 highly reflecting surfaces the transparency may be still further improved through coating the said surfaces with an antireflection layer as known already from the state of the art.

There exist cases where an absolute transparency is not desirable but where the unusual aesthetic aspect may be desired to be more or less maintained: For example in a wristwatch it may be desirable to hide the hairs on the wrist of the wearer. In such cases the interior surface of the second crystal may be provided with a transparent tinted layer which for example may be blued or smoked.

The indicator discs are provided with peripheral teeth. Such teeth are cut right into the material of the disc. In one variant and in order to facilitate machining of the sapphire disc a peripheral metallic crown, of brass for instance, cut in the form of a washer may be applied to the exterior of the disc. It is this external periphery of the crown which will subsequently be cut with much greater facility.

As has been explained in respect of the construction shown in figure 2 a gear train 10 has its gears pivoting about studs 22. In a known construction these studs are integral with the bottom plate and may directly be obtained therefrom for example through milling operations.

This manner of machining (above all where it concerns soft material such as gold for example) does not enable one to obtain a precision axis on which may be pivoted a gear. To remedy this difficulty it has been proposed to drive a sleeve over the stud which sleeve may be precise and around which the gear may pivot. Such construction will result in an axis of large diameter which is undesirable in a watch of small dimensions. Moreover in the mentioned construction the gear backlash is limited by means of a plug forced into the interior of the sleeves, such plug being provided with a collar the diameter of which exceeds the external diameter of the sleeve. This construction is troublesome in that it may no longer be possible to disassemble the gears without damaging the plug which must subsequently be replaced.

Figure 6 proposes in accordance with the invention an improved construction to obviate the difficulties hereabove mentioned. Herein is shown a cross section to a greatly enlarged scale through one of the gears employed in driving the discs. In the bottom plate 1 is force fitted or glued the stud 22. Said stud comprises a stem 41 which may be obtained with sufficient precision to receive directly the pinion 42 on which is force fitted wheel 43. There is thus obtained a sufficiently small diameter to be suitable for the timepiece herein described. Also shown is a base 44 which is force fitted or glued in blind hole 45 arranged in the bottom plate.

Figure 6 also shows how, in accordance with the invention, the backlash of gears 42 and 43 .may be limited. Under cover 2 there is welded glued or fastened in any other suitable manner an elastic blade 46. Such blade which may flex in the sense of the plane of the figure is supported on the free end 47 of the stud. It thus limits the play of gears 42 and 43. Such an arrangement facilitates the disassembly of the elements constituting the watch when cover 2 is removed, since at this moment the gears may be removed without having to disturb the force fitted pieces.

In a preferred version the blade may flex about 0,1 mm in the sense of the bottom plate and approximately 0,05 mm in the sense of the cover, this, thanks to the opening 48 arranged in said cover.

It will be understood that this construction, besides the advantages which it may present for after sales service as already explained above, may enable enlarging the range of tolerances for thickness and out of true in the flat of the cover and of the bottom plate, this field of tolerances being compensated through the range of movement of the elastic blade 46.

It will finally be understood that all gears of the watch may be provided with a system of compensation of play as shown in figure 6 which is an illustration to a large scale of the arrangement for a single gear train only.

Claims

1. Wrist-watch of reduced thickness comprising a case, a crystal and at least two time indicating discs coupled together through a gear train driven by an electric motor controlled by an electronic circuit wherein the overall thickness is constituted by superposition of the back of the case, the time indicating discs and a crystal, there being sufficient play arranged on all sides of said discs to permit free movement thereof, the remaining principal watch elements such as the motor, gear train and electronic circuit being located in portions of the case extending beyond the diameter of the indicating discs, said portions having a thickness no greater than the overall thickness.

2. Wrist-watch as set forth in claim 1 comprising an hours indicating disc and minutes indicating disc.

3. Wrist-watch as set forth in claim 2 wherein the hours indicating disc comprises a metallic disc located proximate the case back provided with a guide mark representing an hours hand, the minutes indicating disc comprises a transparent disc superposed over the hours disc and provided with a guide mark representing a minutes hand and the crystal is provided on its interior face with a dial having engraved or impressed marks thereon.

4. Wrist-watch as set forth in claim 2 wherein the case back incorporates an interior dial with markings thereon and the superposed discs are transparent and provided with guide marks representing respectively an hours hand and a minutes hand.

5. Wrist-watch as set forth in claim 1 wherein the overall thickness is less than 1,6 mm.

6. Wrist-watch as set forth in claim 1 comprising an hours indicating disc, minutes indicating disc and a seconds indicating disc.

7. Wrist-watch as set forth in claim 1 wherein the indicating discs are formed from transparent material having a thickness between 0,05 mm and 0,15 mm.

8. Wrist-watch as set forth in claim 1 wherein the discs are formed from sapphire and includes peripheral teeth cut into the sapphire.

9. Wrist-watch as set forth in claim 1 wherein the discs are formed from sapphire and includes a fitted peripheral metallic crown in which peripheral teeth are cut.

10. Wrist-watch as set forth in claim 1 wherein the case back includes a second crystal, the time indicating discs being transparent and the firstmentioned crystal being provided on its interior face with a dial having engraved or impressed marks thereon thereby to render the assembly transparent thereacross.

11. Wrist-watch as set forth in claim 10 wherein the discs as well as the first-mentioned and the second crystal are provided with an antireflection coating.

1 2. Wrist-watch as set forth in claim 10 wherein the interior face of the second crystal is provided with a tinted transparent coating.

1 3. Wrist-watch as set forth in claim 1 wherein said portions of the case are in the form of two diametrically opposite extensions, one of which incorporates the gear train as arranged to couple the disc together via peripheral teeth on said discs and the electric motor, the other of which incorporates the electronic control circuit and an energy source.

14. Wrist-watch as set forth in claim 13 wherein the electric motor comprises a stator magnetic circuit having two windings.

1 5. Wrist-watch as set forth in claim 13 wherein the electric motor comprises a stator magnetic circuit having four windings.

1 6. Wrist-watch as set forth in claim 1 3 wherein the indicator discs are formed from thin sheets each being driven by an independent gear system from a common driving wheel and guided at their periphery and proximate the driving point by at least one guide means (18) including at least two superposed independent idlers (30, 31) arranged to turn freely on a stud support (32).

1 7. Wrist-watch as set forth in claim 1 6 including two guide means (18,33) situated on both sides of and proximate to the driving point of the discs.

1 8. Wrist-watch as set forth in claim 1 6 wherein the common driving wheel drives directly a minutes indicating disc and indirectly an hours indicating disc via a gear train independent from the minutes indicating disc.

1 9. Wrist-watch as set forth in claim 1 wherein the case back is equipped with studs arranged and adapted to provide bearing support for pivoting of the discs and members of the gear train, beds arranged and adapted to receive various remaining watch elements and a cover member provided with a crystal and adapted to fit onto the case back.

20. Wrist-watch as set forth in claim 1 9 wherein the cover member includes a case band over its entire periphery.

21. Wrist-watch as set forth in claim 1 9 wherein the studs are formed by a stem machined with precision to receive said discs and gear train members and a base member integral with the stem, said base member being glued or driven into a blind hole arranged on the interior of the case back.

22. Wrist-watch as set forth in claim 21 wherein the axial play of the gears is limited by an elastic blade member (46) acting against the free extremity of the stud, said elastic blade member being fixed to the interior wall of the cover member.