EP0696891B1 - Closure for straps of bracelets - Google Patents

Description

The present invention is in the field of closures of bracelets, in particular of wrist watch bands. Spread are mainly buckle closures today. This ensure a secure closure of the two ends of the strap, are slightly the size of the wrist of the wearer of the watch adapt and also inexpensive to manufacture.

The buckle closure is a bit awkward when Applying around the wrist, both when closing and when To open. It requires a relatively stiff watch band because of that Holes that absorb the tensile forces acting in the belt to have. Almost exclusively leather or Plastic in question. Woven textile tapes were found to be Watch straps are more suitable in terms of pattern and color, can not be satisfactory with the buckle closure combine.

There are also mechanical closures instead of the buckles but mainly for use with metal bracelets. Here however, adapting to the size of the wrist is critical and the mechanical fasteners, such as the Springs, make pretty high quality demands on the Manufacturing.

Numerous solutions for closures are known in which the attraction of permanent magnets is used. The German Patent specification DE 2855708 C2 from Kodama discloses a magnetic lock, being a permanent magnet in a magnetic Circle attracts a second closure piece. Doing so Separation force of approx. 4 N (Newton) reached, with no additional mechanical locking, for example by positive engagement is provided. This requires however, relatively strong magnetic fields and security the snatching or before accidental opening of the Closure is still not guaranteed.

Other solutions also involve the attraction of the two closure parts connected to the ends of the tape by permanent magnets, but in the end position still a mechanical lock is provided so that on the two closure parts acting tensile force not by the magnetic Adhesive force but caught by a mechanical lock becomes.

In U.S. Patent 4,622,726, Nakamura discloses a solution when the two locking parts are tightened a part against the other part by a slight rotation is brought into a mechanical catch around its own axis, that can withstand high tractive forces. With this solution is disadvantageous that the locking does not happen automatically, but still requires a special handle.

Such closures with permanent magnets were able to so far not enforced in the field of watch straps and for various reasons.

An important reason surely lies in the fact that the accuracy of all clocks through strong magnetic fields in higher or is less affected. Watches can go through special measures are protected against magnetic fields ("antimagnetic"), but this requires considerable additional effort required.

The quartz watches that dominate the watch market today with analog display are based on a stepper motor that contains a rotating magnet and is therefore very sensitive to magnetic interference fields. Comes when you put the watch down the closure part equipped with a permanent magnet the clockwork to lie, so the accuracy is on improperly disturbed.

The magnetic closures available today meet these requirements regarding the field strength of the stray field when open Apparently not clasp what their use at least Quartz watches still severely handicapped.

The invention relates to a device for a magnetic closure for bracelets, especially for wristwatches, with two Closure parts and with permanent magnets, which are the two closure parts connect by magnetic adhesive force.

By this invention, a magnetic closure for Wristwatches are indicated, even when open in case of accidental contact with the movement, none Impairment of the accuracy of movement causes and also at Quartz watches that do not have a so-called have "anti-magnetic" protection. In addition, the Wrist watch closure according to the invention after assembly of the two closure parts automatically such mechanically lock that opening only by a willful one special handle can be done.

The object is achieved according to the invention by the features of Claim 1 solved. What is achieved by this solution is that in the closed Condition of the strap closure permanent magnet, pole piece and Yoke form a shielded magnetic circuit and also in the open Condition of the closure Permanent magnet and pole piece shielded are.

Advantageous developments of the invention are in the subclaims specified.

The opening in the all-round shielding is areal kept so small that the stray field emerging here below which is also tolerable for the very sensitive movements Field strength remains.

The magnetic lock is very easy to use. At the Closure, the upper closure part is approximately in the middle placed the lower closure part, whereupon the yoke part in the lower part of the opening in the shield slides and thus the automatic locking takes place. The The clasp is released by two fingers by one moderate pressure on the side surfaces of the two closure parts at the band ends is exercised by about 2mm must be moved against each other, whereupon the upper Closure part is free and can be lifted off.

The magnetic circuit housed in the shield can do a lot be built small and only takes about 8mm (in the direction of the belt seen). So that remains in the closure parts enough space to accommodate the two ends of the tape. Small band reserves can be provided at both ends in such a way that the tape length in steps of approx. 5mm can be extended or shortened by a total of 15 to 20mm.

Fig. 1a - 1c die konstruktive Gestaltung der erfindungsgemässen Verschlussvorrichtung anhand eines Ausführungsbeispiels, in perspektivischer Darstellung,

Fig. 2 eine Ausführungsvariante der magnetischen Abschirmung, die den magnetischen Kreis umhüllt, in perspektivischer Darstellung,

Fig. 3: eine Detailvariante des Jochs des magnetischen Kreises, in perspektivischer Darstellung,

Fig. 4a - 4b: zwei Detailvarianten von Anordnungen zur Erzielung einer mechanischen Verriegelung des Jochs im angezogenen Zustand, in Form einer schematischen Schnitt-Darstellung,

Fig. 5: Schnitt-Darstellung durch die Mitte des Magnetverschlusses,

Fig. 6: Detailvarianten für die Anordnung der Dauermagnete, in perspektivischer Darstellung,

Fig. 7: eine weitere Detailvariante für die Anordnung von zwei Dauermagneten, in Form einer horizontalen Schnitt-Darstellung durch die Mitte des Verschlusses,

Fig. 8a - 8c: Fixierung der Band-Enden an den Verschlussteilen und die Verkürzung/Verlängerung des Bandes,

Fig. 9: den für die Öffnung des verriegelten Magnetverschlusses erforderlichen Handgriff.

The invention is explained below using exemplary embodiments and drawings, in which:

1a-1c, the structural design of the closure device according to the invention using an exemplary embodiment, in a perspective view,

2 shows a variant of the embodiment of the magnetic shield, which envelops the magnetic circuit, in a perspective view,

3: a detailed variant of the yoke of the magnetic circuit, in a perspective view,

4a - 4b: two detailed variants of arrangements for achieving a mechanical locking of the yoke in the tightened state, in the form of a schematic sectional view,

5: sectional view through the middle of the magnetic closure,

6: detailed variants for the arrangement of the permanent magnets, in a perspective view,

7: another detailed variant for the arrangement of two permanent magnets, in the form of a horizontal sectional view through the middle of the closure,

8a-8c: Fixing the ends of the tape to the fastener parts and shortening / lengthening the tape,

Fig. 9: the handle required for opening the locked magnetic lock.

1a - 1c show the two closure parts 1 and 2, wherein Closure part 1 rests on the inside of the wrist, while closure part 2 is closed via closure part 1 comes to lie. Both closure parts 1 and 2 have a bowl-shaped Profile, preferably a flat U-profile, where Closure part 2 has a larger clear width than part 1, so that this part is placed over the closure part 1 can. Both closure parts are with side flanges 3 and 3 'or 4 and 4', so that, as shown in Fig. 1, in between a cavity 5 is created.

The magnetic circuit is arranged, enveloped in this cavity 5 from the magnetic shield 6 that is on the drawing Fig. 1c is visible. Two are created on the side of the shield 6 Niches 19 and 20, which are used to fix the two ends of the band 7 and 7 'serve. The straps to be fixed are drawn through hinted like structure.

On the upper closure part 2, this is compared to the magnetic one Circle moving yoke 9 attached so that this when the closure is assembled through the window-like Opening 8 in the magnetic shield 6 in the cavity 5 protrudes.

FIG. 2 shows an embodiment variant of the magnetic shield 6. The shield 6 according to the invention should be such be at least approximately closed. In order to the magnetic field is achieved with an open magnetic circuit i.e. in the absence of the yoke 9 only a very small one Part comes outside the shield 6 and as an interference field for the clockwork, if any, can work. A window-like Opening 8 serves the passage of the moving yoke 9, which on upper closure part 2 is attached. When dimensioning The yoke 9 is therefore also the smallest possible area of the Opening 8 aimed for.

A preferred variant for the production of an all-round Shielding 6 consists in the division into two according to Figure 2, namely in a 5-sided trough with a deep-drawing tool can be manufactured and a lid with side Flanges that can be put over the trough. As a material So-called "soft iron" comes into question and one is very sufficient thin sheet of approximately 0.3mm thickness, which is an excellent Shielding effect guaranteed.

The window-like opening 8 in the shield 6 still takes over the task of locking the two closure parts 1 and 2 in the tightened state by the edge 12 together with a corresponding notch 13 in the yoke 9, as shown in Figure 4a and 4b.

In FIG. 3, the design is greatly enlarged in perspective of the yoke 9 shown. The side surface 10 is there faces the magnetic field and is attracted by it. The Attachment to the underside of the closure part 2 can for example take place over an angle 11 (indicated in FIG 1b).

FIG. 4 schematically shows the inventive method in a sectional view automatic mechanical locking in the locked state. This locking is meant to be the unintended or also violent lifting of the upper closure part 2 in prevent closed state.

4a, the yoke 9 is by a Angle 11 attached to the upper closure part 2 such that a notch 13 of approximately 0.5-1 mm in width is formed. When the yoke is attracted by the magnetic field, the upper one moves Closure part 2 by approximately 2 mm, the notch 13 of the yoke 9 slides over the edge 12 of the shield into the lock. This state is maintained until the magnetic Closure deliberately by a special handle released and thus the lock is released.

Dauermagnet: Punktwolke

ferromagnetische Teile: schraffiert

Magnetische Abschirmung: strichliert.

FIG. 4b shows an embodiment without the angle 11 for fastening the yoke 9 on the closure part 2. The notch is formed by milling the yoke 9 at the connection point to the closure part 2. With this solution, the footprint of the yoke has to be widened so that stable attachment is possible.
5 shows a longitudinal section through the magnetic closure in a large enlargement. For reasons of clarity, the following markings have been made:

Permanent magnet: point cloud

ferromagnetic parts: hatched

Magnetic shield: dashed.

The yoke 9 fastened to the upper closure part 2 is in two Current states shown: Once immediately after However, the two closure parts 1 and 2 are still put together before the horizontal shift under the influence of the magnetic field (dotted lines), then also after successful magnetic suit (solid lines).

The yoke 9 is made of a material with a very low magnetic Permeability manufactured, but contributes a ferromagnetic layer 10 on the magnetic field facing Page. This prevents the magnetic field from over the yoke 9 through the opening 8 in the shield 6 penetrates outside.

The part of the magnetic circuit associated with the closure part (1) is made from at least one permanent magnet 16 and a pole piece 15 Pole shoe 15 is very magnetic with an intermediate layer 14 Permeability, which serves as a footprint, on the inside of the shield 6 attached. The air gaps 22 and 23 prevent a metallic Contact between the side surfaces of the pole piece 15 and the shield 6. The structure according to the invention is such that the magnetic Circle with regard to the shield 6 can be thought of as "floating" can. There is no metallic contact with high magnetic contact Permeability between the magnetic circuit (16, 15, 9) and the shield 6, and also not to any closure parts outside the shield 6.

A marginal field of low field strength only forms on the window-like opening 8 of the shield 6. This portion can also thanks to the clever construction and dimensioning of the closure be minimized.

6 shows two possible variants for the perspective Arrangement of the permanent magnets 16 with a single permanent magnet 16 or with two arranged side by side Permanent magnets 16. In any case, the magnetization is vertical to the front of the permanent magnets 16 and is by arrows marked. When using two permanent magnets 16 is the Choosing an opposite polarity is advantageous, like this is also indicated by arrows. With a relative wide closure can even use three in Spaces of permanent magnets 16 arranged next to one another be advantageous, the corresponding smaller dimensions exhibit.

FIG. 7 shows a variant of the arrangement of the permanent magnets 16 shown as a sectional drawing through the middle the permanent magnet. With this arrangement, two come roughly Permanent magnets 16 arranged at right angles to one another Application, the magnetization and polarity by arrows is marked. The permanent magnets 16 are on a common one Pole shoe 15 attached. The yoke 9 is drawn in two positions, namely in the position immediately after the two closure parts 1 and 2 were added together (dashed) and even after that Yoke 9 was attracted by the magnetic field. The yoke 9 is made of material made with low magnetic permeability, but is on the Contact surface with the pole piece 15 or the permanent magnet 16 with a ferromagnetic layer 23 with high magnetic permeability Mistake. In this way it is avoided that the magnetic field over the yoke 9 penetrates through the opening 8 of the shield 6 to the outside.

This arrangement results in a frictional positioning of the Yokes 9 on the central axis, which is an advantage. There are also certain Advantages in terms of space requirements.

Figures 8a - 8c illustrate the possibility of fixing the two Ends 7 and 7 'of the watch band. With the closure part 1, as shown in FIG. 8 a, the niches 19 on both sides of the shield 6 and 20, which are provided for fixing the band ends 7 and 7 '. With wristwatches, however, it is absolutely essential that the wearer of the watch can shorten and lengthen the belt length by approx. 10 - 15 mm. The strap closure according to the invention enables this in the following way.

A thin approximately U-shaped leaf spring 18 made of steel or Plastic is fastened transversely in the recess 19 in such a way that a pocket arises, which is sufficient to accommodate a small band reserve. The 8b shows a watch strap 21 made of textile material. A such tape can easily be placed on a rigid plastic strip 24 be glued, which makes wrapping possible. The depth of the niches 19 and 20 is enough for 3 - 4 layers of the tape wound on top of each other. In the present example according to FIG. 8b, these are apart from the glued on one Location another two layers.

In most cases it should be desirable to have both niches 19 and 20 to use, with the closure part 2 in exactly the same way a leaf spring 18 is provided and used and the recess 20 for Recording the tape end 7 'is used. This way, both is straightforward an extension as well as a shortening of 10 - 15 mm in 5 mm steps possible.

8b is inserted into the recess 19 and celebrated in this position by the spring 18. Even large tractive forces in the Band 21 is not capable of the band according to FIG. 8c from the niche 19 tug because self-locking of the tape wrap with the leaf spring 18 consists.

The opening of the magnetic closure is shown in FIG. By the locking mechanism operated simultaneously is such that in all activities, including sporting activities, the closure cannot open by itself. This opening happens alone by a handle as shown in FIG. 9. Take for example Thumb and index finger of the right hand on both sides of the closure parts 1 and 2, with the thumb on the overhead Closure part 2 exerts pressure while the index finger on the lower Closure part 1 exerts back pressure. This creates the magnetic adhesive force overcome and the two closure parts move against each other by about 2 mm. All it takes is a slight pressure on the thumb down on the wrist and the closure part 2 jumps to above and can be lifted off.

Claims (6)

1. Device for straps of bracelets, in particular for straps of wrist watches, having a magnetic closure and an automatic mechanical lock, the closure comprising two closure parts (1, 2) and at least one permanent magnet (16) with pole shoe (15) which connects said closure parts by magnetic force, as well as a yoke (9), which jointly form a magnetic circuit,
   charcterized in that,
   the magnetic circuit (16, 15, 9), in closed state of the closure is disposed inside a shield (6) made of ferromagnetic material of high magnetic permeability, which is closed as far as possible on all sides, and is isolated from said shield (6) by air gaps (22, 23) and fastening elements (14) of a very low magnetic permeability close to the value of air and, that in the open state of the magnetic circuit in absence of the yoke (9) only a very small portion of the magnetic field of the permanent magnet (16) with pole shoe (15) extends outside the shield (6).
2. Device according to claim 1,
   characterized in that,
   the yoke (9) is made of a material of low magnetic permeability and at its side facing the at least one permanent magnet (16) carries a layer (10) of ferromagnetic material.
3. Device according to claim 1,
   characterized in that
   the shield (6) is made of non-metallic material and is lined on all sides with a layer of ferromagnetic material.
4. Device according to claim 1 or 3,
   characterized in that
   the shield (6) is constructed in a through- or box-like manner and has a slot-like opening (8) for the passage of a carrier (11) for the yoke (9).
5. Device according to claim 4,
   characterized in that
   an edge (12) of the slot-like opening (8) is used for the mechanical locking of the two closure parts (1, 2).
6. Device according to claim 1,
   characterized by
   two permanent magnets (16),which are disposed at an angle of between approximately 60° and 120° relative to one another on a correspondingly shaped pole shoe (15), as well as by a yoke (9) having a shape corresponding to the end faces of the permanent magnets (16).

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