GB2138976A - Clocks and instruments - Google Patents

Abstract

A clock has removable external 'hour' and 'minute' hands (72,78) which are retained on and moved around a non-magnetic dial (20) by magnetic forces exerted through the dial by magnetic devices (66,68) carried by corresponding 'hour' and 'minute' members (62,64) of a clock mechanism (52) mounted in a peripheral frame (12) to the rear of the dial. The dial is removably retained in that frame by magnetic retaining devices (Fig. 2,28) carried in the frame. The dial is preferably transparent and has hour markings and other decorative matter (24) applied to the protected, rear surface of the dial. The dial may also be provided on its exposed front surface with hour marking and other decorative devices (130) which are removably retained in location recesses (132) by magnetic forces exerted through the dial by magnetic devices (134) secured to the rear surface of the dial. <IMAGE>

Description

SPECIFICATION Clocks and instruments This invention relates to clocks and other instruments of the kind in which one or more indicating hands or pointers (referred to hereafter simply as 'hands') are arranged to move over a front side of a dial or face (referred to hereafter simply as a 'dial') relative to indicia fixed on said front side, and are moved by a driving or actuating means (referred to hereafter simply as a 'driving means') disposed adjacent the rear side of said dial via spindles or arms (referred to hereafter simply as 'spindles') which pass through said dial or around an edge thereof.

In orderto protect the front side of said dial and the said driving means against contamination and discoloration by dust and moisture carried in the atmosphere, it has been commonplace to enclose the dial and its cooperating hands and the driving means completely in a case, which case incorporated for viewing the dial and hands a transparent panel (usually of glass) mounted in a bezel or frame carried on the body part of said case. To permit access to the hands, said transparent panel has often been carried in a bezel which was hingedly mounted on said case body.

In order to clean the dial and hands, it has been necessary to hinge open the transparent panel and preferably remove the hands, and for greatest convenience remove the dial from the case body.

The enclosure of the hands and dial behind a transparent panel (particularly of glass) has the attendant disadvantage that reflections from the surface of the panel can obscure an observer's view of the hands and dial, and can introduce errors in reading the positions of the hands when viewed from oblique directions.

According to one aspect of the present invention, said dial is omitted, and the said indicia are formed on or applied to the inner or rearward side of the transparent panel so as to be visible to an observer through said transparent panel.

According to a second aspect of the present invention, an additional set of hands corresponding to the first-mentioned set of hands is arranged to move externally over the outer or forward side of said transparent panel, magnetic means being provided for supporting the hands of said second set against the outer side of said transparent panel, and for causing those external hands of the said second set to be driven by and in synchronism with the corresponding internal hands of said first-mentioned set. Said magnetic means may comprise a plurality of magnetic devices each of which includes a magnet and an associated magnet keeper.

Various preferred features of the said first aspect ofthe present invention comprise: (a) said transparent panel is provided with an external surface which is externally non-reflective; (b) said transparent panel is supported and retained magnetically in an opening in said case body; (c) said transparent panel is close-fitted in a said opening, and rests against fixed stops disposed in and spaced around said opening, magnetic means being arranged to hold said transparent panel against said fixed stops:: (d) said magnetic means comprises a plurality of magnetic devices likewise disposed in and spaced around said opening, each said magnetic device comprising a magnet (preferably a permanent magnet) and an associated magnet keeper, and each said magnet being secured to one of said transparent panel and said case body, and each said magnet keeper being secured to the other of said transparent panel and said case body.Each said magnet keeper may comprise magnetically-soft material or magnetically-hard material; (e) said magnets or their associated magnet keepers may be mounted in or otherwise constitute said fixed stops; (f) said case body incorporates an opening mechanism for removing the transparent panel from said opening, said mechanism having a rearward part accessible from the rear side of said case body and a forward part arranged for contacting the rear side of said transparent panel and/or any associated bezel, said mechanism being arranged such that movement of said rearward part in an 'opening' direction urges said forward part into contact with said transparent panel and/or bezel whereby to urge said transparent panel away from said stops and thereby separate the said magnet and its associated keeper in at least some of said magnetic devices;; (g) said transparent panel is self-supporting directly in said opening, and has no bezel or frame; (h) said transparent panel is provided centrally on its said outer side with a recess, which recess is arranged to act as a central bearing for said external hands, said external hands being arranged to sweep angularly around the transparent panel.

Various preferred features of the said second aspect of the present invention include the fol lowing:- (a) where said hands comprise linear elements arranged for translational movement by said driving means in a direction transverse to their length dimension, said external hands may comprise slender parallel rollers held by said magnetic means in contact with said outer side of the transparent panel and driven magnetically by said magnetic means; (b) where said hands comprise linear elements arranged for angular movement about a central pivot by said driving means, said external hands may comprise slender tapered rollers, or even spherical rollers, held by said magnetic means in contact with said outer surface of the transparent panel and driven magnetically by said magnetic means:: (c) alternatively, said external hands may comprise linear elements arranged for such angular movement about a central pivot, said elements being formed from thin sheet metal or other material and arranged for angular movement about a pivot pin held magnetically by said magnetic means against said outer surface of the transparent panel.

Said pivot pin may be located at its central position on the transparent panel in a shallow location recess formed in said panel or in a locating member secured to said outer side of the transparent panel, said pivot pin being held in position by a magnetic device having one of its constitutent magnet and keeper members secured on the rear side of said panel and the other of said members secured on said pivot pin.

Where, as in the case of a clock, said hands comprise at least two hands arranged for rotation about a common pivot point, said additional set of hands includes a corresponding plurality of hands supported on and arranged for rotation about a said pivot pin. Each said hand of said additional set is angularly positioned in relation to said transparent panel and to the corresponding hand at the rear side of said panel by a magnetic device spaced radially from said pivot pin, a magnet member of said device being secured on one of the two cooperating hands on one side of said panel and the associated keeper member of said magnetic device being secured on the other of the two cooperating hands on the other side of said panel, the magnetic devices associated with the respective hands of said additional set being positioned at different radial distances from said pivot pin.

Whereas for the hand of said additional set disposed nearer said outer side of the transparent panel the said magnetic device member secured thereto may contact and rub against said outer surface of said panel, two such magnetic device members disposed symmetrically on opposite sides of said pivot pin are required to position the other hand of said additional set in a manner such that said other hand and the magnetic device members secured thereto do not contact or collide with the said hand disposed nearer said outer side of said panel.

Said hand of said additional set nearer said panel is preferably cranked so as to enable the said magnetic device members secured to said other hand of said additional set to be positioned nearer said panel.

Advantageously, said pivot pin may be secured to said other hand of said additional set, so as to rotate therewith.

Other features and advantages of the present invention will appear from the description that follows hereafter, and from the claims appended at the end of that description.

One clock embodying the present invention will now be described by way of example, and with reference to the accompanying diagrammatic draw ings, in which: (a) Figure 1 shows a front elevation of the clock; (b) Figure 2 shows a similar elevation, but with the clock dial or face removed to reveal the clock mechanism; (c) Figure 3 shows a vertical section taken on the section line indicated in Figure 2 at Ill-Ill; and (d) Figure 4 shows an enlargement of part of the section shown in Figure 3, that part being indicated in Figure 3 by the arrow IV.

Referring now to the drawings, the clock compris es a hollow body 10 of square front view and rectangular side view. That body includes a square shaped frame 12 carrying at its underside two bar-shaped feet 14, and having secured in its four internal corners longitudinally-extending stop members 16; an opaque rear closure panel 18 let wholly into the rear of the square opening defined by said frame, so as to abut there the rear ends of said stop members 16; and a front closure panel 20 let wholly into the said square opening at its front end and abutting there the front ends of said stop members 16.

The said front panel 20 comprises a plate of glass 22 of which at least the outer (i.e. forward-facing) surface is matt, and hence non-reflecting. That glass panel carries over its entire inner (i.e. rearwardfacing) surface a sealed decorative layer 24, and at its four corners four soft-iron magnetic keepers 26.

Those keepers cooperate with associated permanent magnets 28 secured firmly in recesses formed in the front ends of the stop members 16, the magnetic attraction between each said keeper and its associated magnet being such as to hold the glass panel firmly and securely in position in the front end of the frame.

The frame 12 carries beneath the upper transverse portion 30 thereof a longitudinally-extending Ushaped bracket 32, in the two dependent end portions of which is slidably carried an axially movable push-rod 34 having enlarged end portions 36. That push-rod is arranged so that when pushed from its rear end, the front end thereof contacts the inner side of the glass panel 20 and urges the upper portion thereof forwardly out of the frame opening against the magnetic attraction of the two magnets 28 mounted in the upper pair of stop members. This enables the glass panel to be removed completely from the frame opening, thereby revealing the clock mechanism mounted inside the frame 12. That mechanism is generally indicated by reference 38.

The decorative layer 24 is constituted by suitable hour and other desired decorative indicia 40 formed deposited on (e.g. by a silk screen process) the rear side of the glass panel 22, and a tough sealing layer of suitable colour and texture applied over said indicia and rear side of the glass panel. The said indicia and the associated background provided by said sealing layer are of course fully visible through the mats front surface of the glass panel.

The glass panel 22 also carries centrally on its outer surface a decorative metal disc 42 in which a central circular aperture serves as a location recess for a magnetically supported pivot pin 44. That pin incorporates at its rear end one of two members which together constitute a magnetic support device, which member is located in said recess and cooperates with the other 46 of said two members, which other member is secured firmly to the glass panel 22 centrally on its rear side. Each said member comprises a small cylindrical permanent magnet, the polarities of the two magnets being such as to attract the pivot pin 44 and hold it firmly with its said rear end located in said location recess.

Mounted within said frame 12 is a transverse bracket 48 secured to the vertical side portions 50 of said frame, on which bracket is mounted an electrically-driven clock movement 52 of the kind incorporating an electric battery for providing the driving power. That clock movement is provided at its forward end with a rudimentary clock face 54 having simple hour markings 56, and through that clock face protrude centrally concentric hour and minute hand shafts 58 and 60. These shafts carry respectively hour and minute indicating members 62,64, each of which extends linearly on either side of its central shaft-receiving aperture. Each such member comprises a flat strip of a non-magnetic material.

The hour indicating member 62 carries near one end thereof (the upper end in the Figures) one small cylindrical member 66 of an hour hand magnetic device.

The said minute indicating member 64 carries near its respective ends at positions disposed symmetrically on either side of the minute shaft 60 two small cylindrical members 68, each of which constitutes one member of one of two similar minute hand magnetic devices.

These magnetic devices associated with the respective hour and minute indicating members 62,64 are intended to support and drive an additional set 70 of hour and minute indicating members (hereafter called the hour and minute hands respectively), which set is disposed adjacent the outer surface of the glass panel.

This additional set 70 includes a slender hour hand 72 of a thin non-magnetic sheet material, which hand is provided at one end with an annular bearing portion 74 which is engaged around the said magnetically supported pivot pin 44. That hour hand carries near its free end, and on its rear side, a small cylindrical member 76 constituting a second member of the said hour hand magnetic device. This latter member is magnetically attracted towards the cooperating member 66 carried by the said hour indicating member 62, and is hence drawn into contact with the outer surface of the glass panel 20.

A thin layer of a low coefficient-of-friction material (such as P.T.F.E.) is secured to the rear face of the said member 76 carried by the hour hand 72, so as to minimise any movement-inhibiting friction due to contact with the glass panel.

The hour hand is cranked in the manner shown to permit the central bearing portion 74 to lie closely adjacent the decorative disc 42.

The said additional set of hands also includes a slender minute hand 78 which extends radially from an integral disc portion 80. That disc portion is secured firmly at a central position on its rear side to the forward end of said magnetically supported pivot pin 44. That disc portion also carries on its rear side two small cylindrical members 82 disposed symmetrically about said pivot pin. These members constitute the respective second members of the two said minute hand magnetic devices, and are attracted magnetically towards the respective members carried by said minute indicating member 64.

In each of said magnetic devices the two constituent cooperating members preferably comprise permanent magnets, though if desired only one such member may comprise such a magnet, the other member then comprising a magnet keeper of a magnetically soft material, such as soft iron.

It will be appreciated that both the hour and minute hands 72, 78 are centrally supported and located by the magnetically held pivot pin 44, and that the respective hands 72 and 78 are driven magnetically by the respective magnetic devices which couple them magnetically with the respective indicating members 62 and 64.

The rear end of the central pivot pin 44 is also fitted with a thin film or layer of a low friction material such as P.T.F.E., so as to minimise the frictional resistance to angular movement of the minute hand. Alternatively, the pivot pin 44 may be fitted at its free end with a thin layer of a hard metal, so as to minimise any tendency of the free end of the pivot pin to wear away with time.

In trials carried out with a clock of the construction shown and described, the hands 72 and 78 of the clock have followed with good positional accuracy the movement of the said hour and minute indicating members 62 and 64 driven by the clock movement. Moreover, the hands 72 and 78 were held firmly in position adjacent the outer surface of the glass panel, and could be dislodged only by a deliberate action to remove them.

For cleaning the outer face of the glass panel, the external hands were readily removable, and cleaning of that face was easily effected with a damp cloth, and without any risk to the indicia and decoration visible through the glass panel. After cleaning the glass panel, the external hands were readily reapplied to that panel, and were securely fixed in their respective positions once they were rotated to seek out the magnetic devices carried by the said hour and minute indicating members 62 and 64.

The facility, to remove the glass panel, is advantageous where the occasional cleaning of the glass panel may be injurious or damaging to the finish of the clock frame, since the glass panel can be readily removed and cleaned away from the frame.

The rear closure panel 18 may be secured in position by screws, or as is preferred, by magnetic means in a manner similar to that used for retaining the front panel 20. In this latter case, means must be provided for enabling the flush rear panel to be eased out of the frame, for example, a small projection protruding from the rear surface of the rear panel could be provided.

It will be appreciated that retaining the front and rear panels in position magnetically greatlyfacilitates access to the various internal parts of the clock for adjustment and cleaning.

Since the clock hands are disposed externally of the clock dial, the difficulties experienced with prior art clocks due to reflections from the front surface of a clock glass disposed in front of the hands do not arise. Moreover, the use of a mattfront surface on said glass panel obviates the possibility that an observer could have his view of the hands obscured by reflections from the glass positioned behind the hands.

Though in the clock-described above, only hour and minute hands are present, the present invention can be applied equally well to clocks having seconds hands in addition. In such a case, the seconds hand would be supported and driven from a correspond ing seconds indicating member by magnetic means in a manner analogous to that used in respect of the hands of the clock described above.

If desired, the rudimentary clock face 54 can be omitted from the clock movement 52.

In one modification of the clock described above, the hour indicating member 62 is replaced by a disc on which is positioned said magnetic device 66, and in addition thereto various other similar members of other magnetic supporting and driving devices.

These other members are positioned around that disc to indicate the respective times at various important places around the world (e.g. New York, Tokyo, Sidney and Moscow), and are used to magnetically support and drive various spherical or tapered rollers (e.g. ball or tapered roller bearings) positioned externally around said glass panel 20 at appropriate 'time' positions. Said rollers may be rendered distinguishable by being differently coloured, or by being positioned at different radial distances from the axis of the clock.

In yet another modification of the clock described above said hands 72, 78 are replaced by slender tapered rollers arranged to be supported externally against the glass panel and to be rolled angularly around the glass panel by the said magnetic devices associated with the said hour and minute indicating members.

In yet another form of the clock described above, the hands 72,78 are omitted and are replaced by appropriately distinguishable spherical rollers for indicating the hours and minutes of time.

If desired, the positions of the indicating members 62 and 64 may be interchanged so that the member 62 is driven by the minute shaft 60 and becomes the minute indicating member, and the member 64 is driven by the hour shaft 58 and becomes the hour indicating member. In such a case, the hand 72 becomes the minute hand, and the hand 78 becomes the hour hand.

With such an arrangement, the central disc portion 80 of the hour hand 78 may be enlarged, and be provided with various indicators for indicating the times at the said various places around the world. By making that disc of a ferro-magnetic material, the said indicators could be constituted by small magnets of different colours placed around the front side of the disc.

Moreover, that disc could be divided into two concentric portions, one for receiving indicators for indicating times of places to the east of the place of operation of the clock, and the other for receiving indicators for indicating times of places to the west of the place of operation of the clock. A distinctive, larger magnetic indicator could also be used to indicate the local time at that place of operation.

Alternatively, said disc portion 80 could be provided with the various place names printed thereon at the respective time positions, and the pointer 78 could then be replaced by a magnetically supported pointer (e.g. in the form of a magnet) whose position on the disc could be adjusted to show the local time in relation to the times at the other places.

The term 'keeper member' as used in this Specification is intended to cover any member which is attracted towards its cooperating magnet. Such a keeper member may comprise a simple piece of ferro-magnetic material, e.g. soft iron, or alternative ly another permanent magnet having appropriate polarity.

One other clock embodying the present invention will now be briefly described by way of a second example and with reference to Figure 5 of the accompanying diagrammatic drawings. That Figure shows a front elevation of the said other clock, various parts in that elevation being shown torn away to reveal other parts normally hidden from view.

Referring now to Figure 5, the clock there shown includes a base or plinth 90 which is square in plan view and rectangular in its front and side elevations.

That base comprises a frame 92 of square configuration similar to that of the frame 12 of the earlier described clock, and an upper plane panel 94 (of a non-magnetic material) which is let wholly into the upper end of a square opening defined by the frame 92, and which is supported and retained there by stop members and associated magnetic retaining devices (not shown), which members and devices are similar to those used in the earlier described clock.

Mounted within the frame 92 is an electric batteryoperated clock movement 96 having uppermost a rudimentary clock dial 98, through which protrude, centrally, concentric hour and minute shafts 100, 102. The hour shaft 100 carries an hour indicating member 104, which extends symmetrically on either side of that shaft, and carries near to its respective ends two similar magentic device members 106 of two respective hour-hand magnetic devices.

Mounted centrally on the panel 94 is a ball race 108, and on that rests an hour hand in the form of a solid, cylindrical pillar 110 bearing near its upper bevelled edge a circle of hour markings 112. Atime index pointer 114 secured on said panel and extending vertically up the side of the pillar indicates the time of day.

The flat base of the hour pillar 110 has secured thereto at diametrically opposite positions two similar magnetic device members 116 which are complementary to and cooperate with those members 106 carried by the hour indicating member 104.

Thus, the hour pillar is angularly positioned and driven by that member 104 as the latter is rotated by the clock movement.

The lower part of the cylindrical surface of the hour pillar is used for decorative and ornamental markings.

With the arrangement so far described, the time is indicated solely by the angular position of the hour pillar relative to the index pointer. However, if more precise indication of the time is required by the provision of a minute hand or its equivalent, this can be readily achieved by mounting a minute indicating member (of a non-magnetic material) on the said minute shaft 102 as indicated in chain-dotted lines at reference 118, by providing it with symmetricallypositioned magnetic device members 120, and by providing a minute pillar (not shown in the Figure) arranged concentrically in and extending through the hour pillar. Such a minute pillar may, if desired, be likewise mounted on a suitable ball bearing race, and be carried by said panel 94 directly, or indirectly through said hour pillar.

At its upper end such a minute pillar may be provided with a cylindrical head bearing around its peripheral surface suitable minute markings for cooperating with a vertical extension of said time index pointer 114. At its lower end said minute pillar would carry two similar magnetic device members which are complementary to and cooperate with those members 120 carried by the minute indicating member 118.

Thus, the minute pillar would be angularly positioned and driven by the minute indicating member 118 as it is rotated by the clock movement.

The said hour and minute pillars may take any suitable form, and be mounted in any suitable way on the said panel 94, but in all cases they will be driven magnetically by means of said hour and minute indicating members disposed below the panel and their associated magnetic devices.

In the description set out above, there are disclosed clocks in which the 'hour' and 'minute' hands (and a 'seconds' hand, if desired) are magnetically retained on, and are driven around, the outer surface of an external clock face. Those hands are readily detachable from the clock face so as to enable that face (and the hands) to be readily and easily cleaned.

Moreover, that clock face is magnetically held in position in the clock body or frame, and is readily removable from that body or frame to facilitate cleaning of the face and to give access to the clock movement or mechanism.

The clock face there disclosed has its hour marking indicia and other, decorative matter planted permanently on the inner surface of the clock face, being visible externally of the clock through the transparent panel which constitutes the clock face.

Thus, to make clocks with different patterns of hour marking indicia and decorative matter, the respective clock face panels have to be treated differently according to the desired clock face markings. The aspect of the present invention that follows seeks to obviate this disadvantage, so that a single design of clock face can be prepared for a whole range of clocks, regardless of the particular forms of markings to be carried on the respective individual faces.

According to this aspect of the present invention, a clock face member comprises a thin, non-magnetic panel or substrate to the rear (i.e. inwardly facing) surface of which are secured in predetermined positions small permanent magnets, and on the front (outwardly facing) surface of which are placed at the said positions hour marking devices and or other, decorative devices, which devices are retained magnetically in position by said magnets, and which devices comprise or incorporate ferro-magnetic or permanently-magnetic materials. Where said devices comprise or incorporate permanetly-magnetic materials, the said magnets secured on the rear surface of said panel may be replaced by ferromagnetic keepers.

The front surface of said panel may be provided with a ring of circumferentially-spaced recesses or depressions for receiving adjacent parts of the respective devices. This ensures accurate mechanical location of such devices, and reduces the risk of dislodgement of said devices from their correct positions opposite the respective magnetic elements secured to the rear surface of the panel. Such recesses or depressions are particularly important where said devices comprise bodies which present rounded-surface portions thereof to said panel. In one convenient embodiment, said bodies advantageously comprise spherical bodies in the form of ordinary commercially-available steel ball bearings, which bearings may if desired be surface-treated to produce desirable aesthetic effects or colourings.

In one clock embodying a clock face according to this present aspect, the external hour and minute hands are constituted as spherical bodies (e.g. ball bearings) which are retained in contact with and driven around the clock face magnetically, said bodies cooperating in the manner described in the aforementioned description above with magnets carried around internally of the clock face on rudimentary hour and minute hands which are themselves driven mechanically by the clock movement.

Other features of the present aspect will appear from the description that follows hereafter, and from the claims appended at the end of that description.

One clock embodying a clock face according to this present aspect will now be described by way of example and with reference to the accompanying diagrammatic drawings, in which Figure 6 shows a front elevation of the clock showing in particular the said clock face and its cooperating hour and minute hands; Figure 7 shows a scrap vertical cross-sectional view of a portion of the clock face, taken on the section indicated in Figure 6 at VII-VII; Figure 8 shows a front elevation of the same clock, but provided instead with an alternative clock face and an alternative form of hour and minute indicators; Figure 9 shows a scrap vertical cross-sectional view of a portion of the alternative clock face of Figure 8, taken on the section indicated in Figure 8 at IX-IX; and Figure 10 shows a view similar to that of Figure 7, of an alternative form of hour markings provided on the clock face of Figure 6.

Referring now to the clock illustrated in the Figures 6 and 7, that clock is, with the exceptions detailed below, identical with that disclosed in the aforementioned description above, and the reader's attention is hereby directed to that earlier description for details of the construction and manner of operation of the clock. In the Figures 6 and 7 the reference numerals used are the same as those used in the earlier description for corresponding parts.

Briefly, the clock body 10 includes a squareshaped frame 12 carrying at its underside two bar-shaped feet 14 and having secured in its four internal corners longitudinally-extending stop members 16; an opaque rear closure panel (18, not shown) let into the rear of the square opening defined by the frame and abutting the rear ends of the stop members; and a front closure panel 20, constituting the clock face, let into the said square opening at its front end and abutting there the front ends of the stop members.

The clock face is held in position magnetically, being provided at its respective corners on the rear side of the panel with soft-iron magnetic keepers which cooperate with small permanent magnets 28 let into the front ends of the stop members 16.

The clock face comprises a thin panel 22 of a transparent, non-magnetic material, such as glass, having secured on its front (i.e. outwardly facing) surface a decorative metal disc 42, and on its rear surface permanent 'hour' and other, decorative indicia 40, the latter being sealed on the panel by a sealing layer (24, not shown) of a suitable colour and texture applied overall on that rear surface.

'Hour' and 'minute' hands 72,78 are magnetically supported in position against the outer surface of the clock face panel 20 by magnetic devices 44,76,82 carried on the rear sides of those hands, which devices cooperate magnetically with corresponding magnetic devices (66,46, 68, not shown) carried on rudimentary 'hour' and 'minute' hands (62,64, not shown) enclosed within the clock frame behind the clock face panel and driven mechanically by a clock movement (52, not shown).

As shown, the permanent 'hour' indicia 40 comprise simple radial lines or bars. To enhance those indicia or markings, other, decorative indicia are applied to, and supported magnetically on, the outer surface of the clock face panel. Those other indicia comprise at the respective 'hour' positions small ferro-magnetic spheres 130 having each a highly reflective external surface, and each being mechanically located in a small circular recess or depression 132 (see Figure 7) formed in the front surface of the clock face panel radially adjacent the outer extremity of the associated radial 'hour' bar 40.

The clock face panel 20 has secured to its rear surface at positions behind the respective recesses 132 small cooperating permanent magnets 134, which magnets attract and thereby magnetically secure in position the respective spheres 130.

The spheres 130 may conveniently comprise commercially-available steel ball bearings, and such may be plated, if desired, with a suitably highly polished decorative metal of a desired colour. Alternatively, each such sphere may be made of a non-magnetic material formed on or around, or attached to, a small ferro-magnetic core, the external surface of the sphere again being coated externally, if desired, with a highly reflective, polished surface layer of appropriate colour.

The recesses 132 may be relatively shallow, provided that they give adequate positional stability to the respective spheres against accidental dislodgement and loss of the spheres; or said recesses may penetrate through the full thickness of the clock face panel, so that the spheres make a limited mechanical contact with the respective magnets secured to the rear surface of the panel, as is shown in the arrangement of Figures 8 and 9.

Referring now to the Figures 8 and 9, the clock of the earlier Figures is shown there with a different clock face 220, which comprises a thin panel of an opaque, non-magnetic material, such as a synthetic plastics laminate (for example, a sheet of material available under the registered trade mark "Formica"). That panel has secured to its rear surface at the respective 'hour' positions a plurality of small cylindrical permanent magnets 23, and the panel has formed in its front surface opposite the respective magnets a plurality of recesses 232 (formed, for example, by means of a countersinking drill) which penetrate through the full thickness of the panel, and in which are received 'hour' indicia in the form of steel ball bearings 230. Each such ball bearing is in mechanical contact with the associated permanent magnet 234, and is hence strongly attracted thereto.

The panel carries on its front surface a decorative central disc 242 (for example, of brass sheet), and an associated decorative concentric annulus 236 of similar material, which annul us is formed with a ring of circumferentially spaced circular apertures 238 which are aligned with the respective recesses 232.

The disc and annulus, which both have plain, polished rim portions 240 and intermediate areas 244 bearing decorative etched line patterns, may be secured permanently to the clock face panel, or they may be magnetically secured on the clock face panel by means of a plurality of circumferentially spaced permanent magnets secured to the rear surface of the panel, keeper members of a ferro-magnetic material being secured to or in the disc and annulus at appropriate positions.

The 'hour' and 'minute' hands 72,78 of Figure 6 are replaced in the clock of Figure 8 by steel ball bearings 272,278 having fine polished surfaces, which ball bearings are magnetically attracted to and positioned on the front surface of the clock face panel 220 by permanent magnets carried by rudimentary 'hour' and 'minute' hands (analogous to the said rudimentary hour and minute hands of the clock of Figures 6 and 7) arranged behind the clock face panel and driven by the clock movement.

In Figure 10 there is shown another form of 'hour' indicia (for replacing the spheres 130 of the clock of the Figures 6 and 7, if desired), which comprise a series of decorative members 330, each comprising, for example, a polished metal or plastics disc or button 332 secured to a small, thin magnetic keeper disc 334 of a ferro-magnetic or permanently magnetic material. Those keeper discs are preferably located in the small circular depressions 132 formed in the front surface of the clock face panel 20, and are retained there by the permanent magnets 134.

The clock face panel 20 (which may be a standard face for a range of clocks) may be given a variety of different appearances bythe use of different forms of such removable hour indicia (130, 230, 330), which indicia are simply and removably planted on the panel and retained there magnetically. For example, one clock face may have hour indica in the forms of the respective signs of the Zodiac; another clock face may have hour indicia in the forms of different aircraft silhouettes; others may have hour indicia in the forms of representations of sports or other cars, or of railway engines, and soon.

The owner of a clock according to the present invention may purchase with or for his clock differents sets of hour indicia, for the purpose of interchanging from time to time the various sets of hour indicia, whereby to give his clock a different appearance. Moreover, since the hour indicia are readily removable, those indicia and the clock face panel may be readily cleaned or refurbished as required from time to time.

The clock face panels 20, 220 may be made of any suitable non-magnetic sheet material, for example, glass, plastics laminates, aluminium, stainless steel, copper, brass, silver, gold. Clock face panels may also be formed by moulding a suitable plastics material, the said permanent magnets being incorporated and the said recesses and permanent decorative matter being formed at the time of moulding.

The hour marking devices may, if desired, comprise artistic arrays of precious and/or semi-precious jewel stones, e.g. brilliants, provided with suitable ferro- or permanent-magnetic backing members for location in said recesses formed in the front surface of the clock face panel.

Claims (29)

1. A clock, or other dialled instrument, having a dial or face, and a time or other function indicating means (referred to hereinafter as the external indicating means) disposed adjacent to a front, exposed, external surface of the dial and arranged for movement relative thereto by a driving mechanism mounted behind the rear, enclosed, internal surface of the dial, wherein the driving mechanism has a time or other function indicating means (referred to hereinafter as the internal indicating means) disposed adjacent to the said rear surface of the dial and moveable relative to that surface by said mechanism, and wherein cooperating, complementary magnetic devices carried on said internal and external indicating means respectively drive the external indicating means relative to said front surface of the dial in synchronism with the movement of the internal indicating means relative to said rear surface of the dial.

2. An instrument according to Claim 1, wherein said complementary magnetic devices are arranged in such a manner as to hold said external indicating means in position relative to said front surface of the dial.

3. An instrument according to Claim 1 or 2, wherein said internal and external indicating means each comprise a rotary indicating means arranged for angular movement about a common axis of rotation when driven by said driving mechanism.

4. An instrument according to Claim 3, wherein said external rotary indicating means and said rear surface of the dial both carry cooperating magnetic devices disposed coaxially on said axis of rotation and arranged to magnetically hold, in the manner of a pivot, said external indicating means for rotation about said axis.

5. An instrument according to Claim 3 or 4, wherein said external rotary indicating means comprises a plurality of independently movable, external rotary indicating members arranged for angular movement about a common axis of rotation, and said internal rotary indicating means comprises a corresponding plurality of internal rotary indicating members arranged to be driven in a predetermined coordinated manner by separate, co-axially disposed, output driving shafts of the said driving mechanism respectively, which shafts are aiigned with said common axis of rotation.

6. An instrument according to Claim 5, wherein one of said external rotary indicating members and its corresponding internal rotary indicating member carry at respective positions spaced from said axis of rotation two sets of complementary magnetic devices, which devices align said one external rotary indicating member with said corresponding internal rotary indicating member.

7. An instrument according to Claim 6, wherein another of said external, rotary indicating members and the corresponding internal rotary indicating member respectively carry at a position spaced from said axis of rotation complementary cooperating magnetic devices for angularly positioning said external rotary indicating member, said another external rotary indicating member being carried at said common axis of rotation on a pivot member held on said external surface of said dial and positioned co-axially with said axis of rotation.

8. An instrument according to Claim 7, wherein said pivot member is held in position on said external surface of said dial magnetically by complementary magnetic devices, one of which is secured to said rear surface of said dial, and the other one of which is secured to or constituted by said pivot member.

9. An instrument according to Claim 8, wherein said pivot member is secured to the said one of said external rotary indicating members.

10. An instrument according to Claim 9, wherein said another of said external rotary indicating members is cranked so as to position the part thereof carried on said pivot member adjacent said external surface of said dial.

11. An instrument according to Claim 9 to 10, wherein said pivot member and the magnetic device carried by the said other external rotary indicating member are provided with low-friction, wearresisting surfaces for contacting the said external surface of said dial.

12. An instrument according to any one of the claims 3 to 11, wherein said dial bears a circular array of time or otherfunction markings, and said external rotary indicating means defines the time or other function value with reference to that array of markings.

13. An instrument according to Claim 12, wherein said external rotary indicating means comprises a single radial arm or a plurality of radial arms arranged for angular movement about said common axis of rotation.

14. An instrument according to Claim 12, wherein said external rotary indicating means comprises a single roller member or a plurality of roller members, each such roller member being held against the said dial and rolled along the external surface thereof by the magnetic cooperation af such roller member with a complementary magnetic device carried by the corresponding internal rotary indicating means or member.

15. An instrument according to Claim 14, wherein each said roller member comprises a tapered roller or a spherical roller.

16. An instrument according to any one of the Claims 3 to 11, wherein said dial carries one or a plurality of time or other function reference devices, and said external rotary indicating means comprises one or a plurality of ciruclar or cylindrical rotary members, each such rotary member bearing a circular array of time or other function markings by reference two which said reference device or devices define the time or other function value.

17. An instrument according to any preceding Claim, wherein said dial is secured magnetically to a peripheral frame by means of one or more sets of cooperating complementary magnetic devices carried on said dial and said frame.

18. A clock according to any preceding Claim, substantially as hereinbefore described with reference to and as illustrated by any relevant single Figure or group of associated Figures of the accompanying diagrammatic drawings.

19. A clock or other dialled instrument comprising an operating or driving mechanism enclosed within a peripheral frame between front and rear transverse panel members, wherein one or each said panel member is held within said frame by one or more sets of cooperating complementary magnetic devices carried on said frame and the or each said panel member.

20. An instrument according to any preceding Claim, wherein said dial comprises a transparent or translucent panel member, and the enclosed internal surface of that panel member bears time or other function markings, reference markings or devices, and/or decorative markings or devices.

21. An instrument according to any one of the Claims 1 to 17, 19 and 20, wherein the said dial or face comprises a thin, non-magnetic panel or substrate to the rear, internal surface of which are secured in predetermined positions small magnetic devices, and on the front, external surface of which are positioned at the said positions hour (or other function) marking devices and/or other decorative devices, which markings or decorative devices comprise complementary magnetic devices and are retained magnetically in position by magnetic cooperation with the corresponding magnetic devices secured to the rear surface of the dial.

22. An instrument according to Claim 21, wherein the magnetic devices secured to the rear surface of the dial comprise permanent magnets.

23. An instrument according to Claim 21 or 22, wherein the front surface of the dial is provided with a ring of circumferentially spaced recesses for receiving adjacent parts of the said hour marking or decorative devices.

24. An instrument according to any one of the Claims 21 to 23, wherein the said hour marking devices are constituted by spherical ferro-magnetic bodies.

25. A clock having a dial or face constituted by a thin, non-magnetic panel or substrate to the rear, internal surface of which are secured in predetermined positions small magnetic devices, and on the front, external surface of which are positioned at the said positions hour (or other function) marking devices and/or other decorative devices, which markings or decorative devices comprise complementary magnetic devices and are retained magnetically in position by magnetic cooperation with the corresponding magnetic devices secured to the rear surface of the dial.

26. A clock according to Claim 25, wherein the magnetic devices secured to the rear surface of the dial comprise permanent magnets.

27. A clock according to Claim 26, wherein the front surface of the dial is provided with a ring of circumferentially spaced recesses for receiving adjacent parts of the said hour markings or decorative devices.

28. A clock according to Claim 27, wherein the said hour marking devices are constituted by spherical ferro-magnetic bodies.

29. A clock according to any one of the Claims 19 to 28, substantially as hereinbefore described with reference to and as illustrated by any relevant single Figure or group of associated Figures of the accompanying diagrammatic drawings.