EP0845718A1 - Electric switching means on a printed circuit board and watch comprising such a switch - Google Patents

Abstract

An electric switch device (14) co-operating with a printed circuit (13) and closing perpendicular to such circuit when it is actuated by a pressure in a direction (A) parallel to the plane (16) of the circuit. The switch comprises an elastic contact element (22) having a prominent portion (25) which receives the pressure from a push-button (4) in a direction (A) parallel to the printed circuit. At least one flexible leg (28) of the contact element is fixed to the printed circuit or close to the latter. Another leg (26) of this contact element carries at its end a contact portion (27) which is lowered onto a pad of the circuit when the contact element bends under the effect of the control pressure.

Description

The present invention relates to a device electrical switch on a printed circuit having an insulating substrate which extends substantially in a plane in the region of the switch and which carries at least one conductive pad of the printed circuit, the device further comprising a fixed contact piece at a fixed point of attachment relative to the substrate, said part being elastically deformable between a position of rest where it does not touch the conductive surface and a latching position where a contact part of said part is in contact with said range, and a control member which is movable in a direction of thrust substantially parallel to the plane of the substrate and to distance from said plane to apply thrust in said direction to the contact part in order to put it in its position of engagement.

The invention also relates to a watch comprising a box and such a device in the box.

In most switches mounted on a printed circuit and closing by manual pressure on a control key, this pressure acts perpendicular to the plane of the printed circuit, because it is the simplest construction. There are, however, case where the control unit must be placed laterally and act parallel to the circuit plane. A typical case is that of watches, for example chronograph watches or multifunctional watches, where a printed circuit is generally parallel to the bottom and to the upper side of the watch case, while we prefer place the control buttons on the sides of the box, rather than on the top side where they would be exposed to untimely actuation by contact with foreign bodies. The usual solution then consists to use, opposite each push-button, a switch placed outside the printed circuit and closing in the direction of action of the pusher, therefore parallel to the plane of the printed circuit. This results in a bulk which is annoying in a small object such as a box of watch. The publications US-A-4,062,181, US-A-4,122,664 and EP-A-0 703 512 describe devices of this kind.

We know from US-A-4,423,966 an alarm clock table provided with a type of switch having a blade of flexible contact mounted directly on a flat substrate and operated by a control button which slides in a slot parallel to the plane of the substrate. The blade has a very open inverted V shape, to present a ramp at low inclination serving as a cam against which the control button is pressed while sliding to lower the blade by bending until the free end of the blade goes to touch a contact pad on the substrate. This construction is not suitable for a watch, because that you can hardly seal in the area of the slot and also because such a switch is too imprecise to control time functions. In in addition, the friction of the button on the cam surface is troublesome for the operator and cause wear.

US-A-4 144 428 describes a switch of the genre defined in the preamble above, i.e. converting the control movement parallel to the plane of the substrate in a closing movement of the contact electric by deformation of the contact piece for the move closer to the substrate carrying the conductive surface on which it should apply. A metal frame in inverted rectangular U shape is fixed on a card circuit board supposed to be horizontal and supports a rod horizontal pusher that can slide through the built. The contact piece is a flexible blade having a fixed support point against an interior angle of the frame and a mobile support point formed by a collar of the rod. When we push the rod, the blade bulges down and goes touch a conductive pad on the printed circuit. This construction is relatively heavy and bulky on the printed circuit and also poses problems of lubrication and wear which can affect its operation.

The object of the present invention is to avoid disadvantages of the prior art, by creating a device switch on a printed circuit very simple and inexpensive construction, a reliable operation and small footprint, allowing in particular its use in an object of small size such as a wristwatch.

To this end, a first aspect of the invention relates to an electrical switch device of the kind indicated above, characterized in that the point is located near the plane of the substrate and in that the contact piece is flexible between the point of attachment and a point of application of said thrust, so that it bends under said thrust and that the part of contact follows an approximately trajectory perpendicular to the plane of the substrate when it enters contact with the conductive surface.

So, assuming for example that the substrate is horizontal, when the control member is actuated to close the switch, the contact part flexes mainly in the vicinity of its attachment point located at proximity to the substrate plane and preferably in this plan itself, so that the rest of the room performs a substantially pivoting movement around this area of main bending. As the contact part of the room is also close to the plane of the substrate, its trajectory is then descending, so approximately perpendicular to this plane. However, the point application of the thrust is distant from this plane and follows therefore a trajectory with a horizontal component. This trajectory can be completely horizontal if the point application of the thrust is vertical to the main bending zone.

Preferably, the contact piece includes a prominent part located at a distance from said plane, a first branch attached to the prominent part and comprising the contact part, and a second branch flexible attached to the prominent part and fixed to the attachment point, the point of application of the thrust being located on the prominent part or near this one.

In a device according to the invention, the point of the contact piece can be found either on the substrate, so that the part is integral with the printed circuit, either on another fixed element by relation to the substrate, so that the printed circuit has a smaller footprint, especially for the storage. If the attachment point is on the substrate, the printed circuit may have a second range conductive which is electrically connected to the workpiece contact at the point of attachment. In addition, the part protruding from the contact piece, comprising the point application of the thrust, may extend beyond a edge of the substrate in the direction of the control member, especially if one wishes that this organ does not extend not above the printed circuit.

A second aspect of the invention relates to a watch comprising a box and a device according to the first aspect of the invention, the watch being characterized in that that the plane of the substrate is substantially parallel to a bottom of the box and in that the control member includes a manual pusher arranged in a middle part of the box and having, opposite the contact piece, a bearing surface perpendicular to the direction of thrust.

This means that we have a contact electric closing directly on the printed circuit, perpendicular to it, under the action of a pusher disposed laterally in the watch case and which may be, in particular, of conventional construction. In a particularly simple embodiment, the pusher can be formed by a deformable element in elastomer.

Depending on the case, the bearing surface of the pusher can be arranged to bear directly against the workpiece contact, or a transmission element, in particular in ball shape, can be interposed between the surface support of the pusher and the contact piece, said element being guided in the box to be mobile in the thrust direction.

• la figure 1 est une vue en coupe partielle d'une montre comportant une forme de réalisation préférée d'un dispositif d'interrupteur électrique selon l'invention,
• la figure 2 est une vue agrandie en élévation latérale de la pièce de contact de l'interrupteur représenté à la figure 1,
• la figure 3 est une vue agrandie en plan de l'interrupteur représenté à la figure 1,
• la figure 4 est une vue analogue à la figure 1 représentant une autre forme de réalisation,
• la figure 5 est une vue en plan de la pièce de contact illustrée à la figure 4, et
• la figure 6 représente une variante du dispositif illustré à la figure 4.

Other characteristics and advantages of the present invention will appear in the following description of various exemplary embodiments, with reference to the appended drawings, in which:

• FIG. 1 is a partial sectional view of a watch comprising a preferred embodiment of an electrical switch device according to the invention,
• FIG. 2 is an enlarged view in side elevation of the contact part of the switch shown in FIG. 1,
• FIG. 3 is an enlarged plan view of the switch shown in FIG. 1,
• FIG. 4 is a view similar to FIG. 1 showing another embodiment,
• FIG. 5 is a plan view of the contact part illustrated in FIG. 4, and
• FIG. 6 represents a variant of the device illustrated in FIG. 4.

The watch partially shown in Figure 1 includes a box 1 comprising a bottom 2, a middle part 3 equipped with one or more lateral pushers 4, one bezel 5 and a lens 6 covering display means digital or analog, for example needles not represented and a dial 7. Between the bottom 2 and the dial 7 is a central compartment 8 which contains a watch movement not shown.

In the present example, the back 2 and the middle part 3 are formed by a single piece of synthetic material, on which the bezel 5 is also welded in material synthetic. Glass 6 is welded or glued to the telescope 5 and maintains the dial 7. The pusher 4 shown is a deformable elastomer part, housed in an orifice lateral of the middle part 3 and preferably produced by overmolding. The pusher 4 has a central axis 9 parallel to the bottom 2 of the box, a head 10 projecting from the outside of the box, and a bearing surface 11 disposed on a protrusion 12 of the pusher inside of the box in front of compartment 8. This surface 11 is preferably flat and perpendicular to the bottom 2 when the pusher is at rest. In a plan perpendicular to that of FIG. 1, the pusher 4 can for example have a circular or oblong shape.

However, it should be noted that other types of push buttons or controls can be used in the context of the present invention, as is will describe later, provided that the actuation of such control device causes displacement of the surface support 11 in a thrust direction A parallel to axis 9 of the pusher.

Compartment 8 contains a printed circuit 13 fitted with an electrical switch 14. The printed circuit 13, which may be of a conventional type, comprises a insulating substrate 15 consisting of a relatively card rigid which extends in a substantially parallel plane 16 at the bottom 2 of the box 1. In the example shown, the substrate 15 is fixed directly on the bottom 2, but it could be attached to any other fixed element in the box. On the upper face of the substrate, the circuit printed 13 includes conductive tracks 17, 18 connected to respective conductive pads 19, 20 (Figure 3) which are part of the switch 14 with a metal contact piece 22 fixed to the printed circuit 13 by means of two rivets constituting two attachment points 23 of Exhibit 22. Figures 2 and 3 show more in detail the shape of the contact piece 22 which has been cut from a metal sheet and folded. This piece has a protruding portion 25 raised relative to to the substrate 15, therefore located at a distance from the plane 16 of the substrate and extending opposite the bearing surface 11 pusher 4 (Figure 1). In the middle of the game prominent 25 is attached one end of a first flexible leg 26, the other end of which is slightly bent upwards, constitutes a contact part 27 located above the conductive surface 20 of the printed circuit 13. On either side of the first branch 26, each end of the protruding part 25 is connected to a respective second flexible branch 28, the other end of which 29 constitutes a foot which is fixed to the printed circuit 13 by the corresponding rivet. The Figure 3 shows that one of the feet 29 is applied to the conductive pad 19, this being connected for example at the ground pole of the printed circuit by the track driver 17.

When the head 10 of the pusher is pressed manually 4, its bearing surface 11 moves in the direction of arrow A, up to the latched position drawn in broken lines in Figure 1, and grows in the same direction the prominent part 25 of the piece of contact 22. This push causes the second to flex branches 28 of part 22 where the bending moment is the largest, i.e. in a bending zone main 30 (figure 2) located near the point attachment 23 corresponding. This bending has the effect lower the contact part 27 until it comes into contact with the conductive pad 20, closing switch 14 to establish a connection electric between tracks 17 and 18 of the printed circuit. In this position, the flexibility of the first branch 26 avoids the need for a stop in the pusher 4.

When you release the pressure on the pusher, it and the contact piece 22 resume by elasticity their rest position drawn in solid lines, so that the switch 14 reopens.

An advantage of the configuration which has just been described in contact piece 22 is that its part prominent 25 can be found, in plan view, beyond of an edge 31 of the printed circuit 13, so that this edge does not need to be close to pusher 4. This can also allow a reduction in length of the pusher.

In the embodiment illustrated by Figures 4 and 5, the watch case 1 comprises a pusher made of elastomer 34 having a deformable central body 35 circular or oval bell shape, anchored by overmolding in the middle 3 of the watch case 1. The pusher 34 has a projecting outer head 36 and an inner rod 37, the end of which forms a bearing surface 38 perpendicular to the axis 39 of the pusher, therefore to the thrust direction A and on the plane of the printed circuit 13. An insulating plastic ball 40 is interposed between this surface 38 and the contact piece 42 of the switch 14, this ball being guided in a duct of the box 1 so as to slide in the direction A when pushed by pusher 34 and in the opposite direction when it is pushed back by the workpiece contact 42.

The contact piece 42 has a shape different from the part 22 described above, but it works from analogously. It basically includes a blade metallic folded in a general inverted U shape, to form a prominent curved portion 43 between a first branch 44, the bent free end of which forms the contact part 45, and a second flexible branch 46 having at its end an enlarged foot 47 which is fixed to the printed circuit 13 by two rivets constituting its points attachment 48. When the pusher 34 is pressed, the ball 40 leans against the prominent part 43 or the top of the second branch 46 of the contact piece 42, for flex the bottom of this branch to the position as shown in broken lines in the figure 4. The contact part 45 thus lowers vertically to apply on the contact pad corresponding of the printed circuit.

The presence of the ball 40 has the advantage of allowing, if necessary, a certain distance between the pusher 34 and the switch 14. It also allows insulation electric between the switch and the pusher, in particular if it is metal.

However, it is also conceivable that the piece of contact 42 described above is controlled by a push button applying directly against it.

In the variant illustrated in Figure 6, the only difference from the device in Figures 4 and 5 is that the contact piece 42 is not fixed on the printed circuit 13, but on another fixed part 50, for example a metal part electrically connected to the mass. If the bottom 2 of the box is metallic, the part contact 42 can even be fixed directly to it. The advantage of this variant is that the printed circuit 13 thus has a reduced overall height and length, allowing it to be stored and handled more easily. This variant can also have the interest in cases where the substrate of the printed circuit is flexible and / or curved, or in general of a nature which does not allow the contact piece to be easily attached to it.

Although the invention is described by its application in a watch, it is understood that its field of application extends to all kinds of others uses of a switch on a printed circuit, with control device of various types such as buttons, pushers, levers and the like, in the extent that this organ acts in a direction substantially parallel to the printed circuit.

Claims (12)

Electric switch device on a printed circuit (13) comprising an insulating substrate (15) which extends substantially in a plane (16) in the region of the switch (14) and which carries at least one conductive pad (20 ) of the printed circuit, the device further comprising a contact part (22, 42) fixed to an attachment point (23, 48) fixed relative to the substrate, said part being elastically deformable between a rest position where it does not not touch the conductive pad and an engagement position where a contact part (27, 45) of said part is in contact with said pad, and a control member (4, 34) which is movable in a thrust direction ( A) substantially parallel to the plane of the substrate and at a distance from said plane in order to apply a thrust in said direction to the contact piece in order to put it in its latching position,
characterized in that the point of attachment (23, 48) is located near the plane (16) of the substrate (15) and in that the contact piece (22, 42) is flexible between the point of attachment and a point of application of said thrust, so that it flexes under said thrust and that the contact part (27, 45) follows a trajectory approximately perpendicular to the plane of the substrate when it comes into contact with the conductive pad. Device according to claim 1, characterized in that the contact part has a part prominent (25, 43) located at a distance from said plane (16), a first branch (26, 44) attached to the part prominent and comprising the contact part, and a second flexible branch (28, 46) attached to the part prominent and fixed at the point of attachment, the point application of the thrust being located on the part prominent or near it. Device according to claim 1 or 2, characterized in that the attachment point (23, 48) is found on the substrate. Device according to claim 3, characterized in that the printed circuit has a second area conductive (19) which is electrically connected to the contact piece (22, 42) at the point of attachment. Device according to claims 2 and 3, characterized in that the prominent part (25) of the contact piece (22) extends beyond an edge (31) of the substrate (15) in the direction of the control member. Device according to claim 2, characterized in that the contact piece (22, 42) is a piece cut from a metal sheet and folded. Device according to claim 6, characterized in that the protruding part (25) has an elongated shape substantially perpendicular to the direction of thrust (A) and in that the contact piece has two second branches (28), attached to respective ends of the prominent part and attached to attachment points respective (23), and a single first branch (26) attached to the prominent part between the second branches. Device according to claim 6, characterized in that the contact piece (42) is a bent blade in a general U shape, the curved part of the U forming said protruding part (43). Watch comprising a box (1) and a device according to one of the preceding claims in the box, characterized in that the plane (16) of the substrate (15) is substantially parallel to a bottom (2) of the box and in that that the control member comprises a manual pusher (4, 34) arranged in a middle part (3) of the box and having, opposite the contact piece, a surface support (11, 38) perpendicular to the thrust direction (AT). Watch according to claim 9, characterized in that the pusher (4, 34) is formed by an element deformable into elastomer. Watch according to claim 9 or 10, characterized in that the bearing surface (11) of the pusher is arranged to bear directly against the workpiece contact. Watch according to claim 9 or 10, characterized in that a transmission element, in particular in the form of a ball (40), is interposed between the bearing surface (38) of the pusher and the contact piece (42), said element being guided in the box to be movable in the thrust direction (A).

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