HK1036331B - Multi-function push-button contact clamp - Google Patents

Description

Multifunctional button contact splint

Technical Field

The invention relates to a multi-functional contact jaw, which is made in a single piece of simple and economical design, which acts like a key to prevent the button from moving after it has been set in position, and also acts like a return spring in the middle position and contact means, for example on a printed circuit contact pad.

The invention also relates to a contact arrangement in which several clamping plates of the aforementioned type are arranged end to end.

Background

Such a clamping plate or contact device finds application in a very wide range of fields, in particular in the control of small electronic devices, such as timepiece components.

In push button devices it is known to use elastic members to perform some of the functions of the key/return spring/contact means, as long as a contact force is desired which is less than the force necessary to act on the push button head, in particular when said contact is established on a printed circuit contact.

In swiss patent No. 621034, a control mechanism for the movement of a watch comprises a wire spring, which is disposed between two support members arranged on either side of the button stem and the median portion of which is engaged in a recess of said stem, thus achieving the dual action of the key member and the return spring, such contact being ensured by the end of the button acting on an inclined spring.

In us patent No. 4818830, a push button mechanism is made by a flat metal spring cut along a complex, generally U-shaped profile and secured and/or guided by several bolts secured to a plate, so that one limb has sufficient resilience to close a contact when force is applied thereto via the end of the push button stem. The mechanism thus performs the function of a return spring and contact arrangement but without the function of a key.

The mechanism proposed in british patent No. 2040517 is formed by a pre-cut metal leaf spring which includes a number of bent portions at the outer sides thereof parallel to the general plane of the plate. The spring plate is fixed at one end thereof by a bent portion fixed to the plate and by a bolt fixed to the plate. On the button stem, and close to its end, the leaf spring has a step whose plane is lower than the general plane of the plate and is located in a groove made for this purpose. The end portion comprises, on the one hand, an opening, one edge of which is engaged in a recess of the button stem to form the key and the return spring, and, on the other hand, a rigid projection bent towards the outside of the plate and arranged along the axis of the button stem to form a contact on an elastic spring leaf situated on the opposite side. A rigid tip extending to the outside of the stem abuts a stop against an edge of the opening to properly position the button and wind the leaf forming the spring. This configuration enables the spring/key/contact function to be ensured by a single leaf, but it should be noted that on the one hand not only a leaf is shaped but also a hollow deformation has to be provided in the plate, and on the other hand the force acting on the button head is directly exerted at the contact point, which can thus only be formed by a strip spring.

Disclosure of Invention

The object of the present invention is to overcome the drawbacks of the prior art cited above by providing a contact jaw formed by a metal spring plate cut and bent to ensure at least the functions of spring, key and contact, while also allowing to obtain a contact force that is less than the force to be exerted on the button head.

The invention therefore relates to a multi-functional contact cleat associated with at least one push-button having a head and a stem passing through the middle of a casing closed by at least one back cover and comprising a plate and a metal grid, characterized in that: said contact jaw is formed by a single piece comprising a flat metal base substantially parallel to the back cover and provided with means for its fixing in the housing on one side of the stem and at least one elastic strip spring substantially perpendicular to the base, which extends beyond the stem and follows a portion of the inner periphery of the intermediate piece, said strip spring having a first pre-stressed portion opposite to the stem, which has a cut cooperating with a groove arranged close to the end of the stem to form the key and the return spring in the unloaded position, and a second portion having an elasticity greater than the first portion and whose end can close a contact of the printed circuit with a force less than the force required to actuate the button.

In the case of several buttons on the casing, for example when the casing is a chronograph stopwatch, a contact plate of the aforementioned type can be arranged facing each button. According to a preferred embodiment, the base of each contact jaw is positioned end-to-end to form a single base along the periphery of the intermediate portion comprising a plurality of spring strip springs.

Drawings

Further advantages of the invention and the manner of carrying out the invention will be explained in more detail in the following description with reference to the drawings, in which:

figure 1 is a top view of a watch case including a multi-function contact cleat according to the present invention;

FIG. 2 is an enlarged perspective view corresponding to FIG. 1;

FIG. 3 is a cross-sectional view of the button taken along line III-III of FIG. 1;

FIG. 4 is a cross-sectional view of the contact spring taken along line IV-IV of FIG. 1;

fig. 5 is a top view of an embodiment of a contact cleat mounted to more than one button.

Detailed Description

With particular reference to figures 1 to 4, the case for an electronic watch with a digital display comprises a middle part 2 and a back cover 3 made in a single piece, which are jointly represented by the back cover middle part 4/and are obtained, for example, by moulding a plastic material. The back cover 3 comprises a plate 5 and a metal grid 15 shaped to house and position various timepiece elements, of which only a LCD (liquid crystal display) display module 6 is shown in the figures, under which is arranged an elastic printed circuit 7 provided with a tab 8 bent over the edge of the display unit 6 to act as a contact area. The housing is closed by a quartz crystal 9 (watch skin). The housing 1 includes a' mechanism that allows a contact to be established on the contact Pad (Pad) of the bent tab 8 of the printed circuit 7. The mechanism is formed only by a metal multi-function contact clamp 20, which clamp 20 is actuated by a push button 10, on the head 11 of which button 10a force F is exerted, which force is transmitted by a stem 12, which stem 12 comprises a groove 17 near its end, as can be seen in fig. 3. The contact clamping plate 20 is obtained by cutting or punching a sheet of metal along a specific contour and bending it so as to simultaneously fulfil the functions of key member, button return spring and contact means after it has been arranged positioned in the housing.

With particular reference to fig. 1 and 2, it can be seen that the contact jaw 20 essentially comprises a base 21 parallel to the general plane of the housing and a flat spring 22 perpendicular to the base 21, wherein a first portion 23 of the flat spring 22 is connected to the base 21 over a portion of its length by a bent portion 21 a. The first portion 23 extends to a second portion 24 beyond a bent portion 23a, and the second portion 24 will extend beyond the stem 12. The portion 24 includes a cut-out 30 in its middle which will engage in the recess 17 of the shank 12 to form a key member. As will be seen later, the positioning of the bent portion 23a and of the base 21 with respect to the inner surface of the intermediate portion 2 is obtained so that the free portion of the first portion 23 beyond the bent portion 21a and the second portion 24 are prestressed so as to together form a return spring of the push-button 10 in the unloaded position.

The strip spring 22 extends beyond the push button by a strip-shaped portion and is connected to the second portion 24 by a bent portion 24a, and is formed with three portions 25, 26, 27 which are connected to each other by bent portions 25a, 26a, wherein the region 27 has at its end a small projection 28 which is bent along the bent portion 27a so that the strip spring is deformed in a direction opposite to 'the deformation obtained by bending all of the bent portions 23a, 24a, 25a and 26a in the same direction', thereby bending the strip spring along a polygonal line which substantially follows the inner wall of the intermediate portion 2. The curved shape of portion 25 is obtained only by the structural stresses associated with the other elements or supports of the movement. The strip-shaped portion formed by the regions 26 and 27 is characterized in that: over most of its length, for example starting from the middle of the region 26, has a smaller cross section than the rest of the flat spring.

In the example shown, this smaller cross-section is obtained by making the end portion of the flat spring 22a smaller width than the portion connected to the base, as is also evident in the sectional views of fig. 3 and 4. This configuration gives the end portion a greater elasticity, so that the bent tab 28 is pressed against the contact pad 8 of the printed circuit 7 with a force F that is less than the force F that has to be exerted on the push button.

This difference in resilience can equally be obtained in different ways, for example by making a strip of spring of the same width from one end to the other, but cutting a window in the end portion or making this portion thinner. Similarly, a strip of spring with a greater number of bends can be made until it is perfectly curved to follow the internal contour of the intermediate portion.

The base 21 of the contact clamping plate 20 also comprises a blade 29 bent outside the general plane of the casing to establish, through the grid 15, a contact between, for example, a region of the printed circuit 7 and the positive pole of the battery cover.

In order to allow the base 21 of the contact-making plate 20 to be fixed to the plate 5, the latter (21) comprises two holes 18, 19 in which two bolts 13, 14 engage, which are fixed to the plate so as to allow precise positioning in the horizontal plane, the assembly being axially retained by two welds 16 on the grid plate 15. It is clear that other equivalent means can be used to obtain the axial positioning, such as deforming the heads of the bolts 13, 14 or providing them with cooperating washers on their ends.

As can be seen, the multi-functional contact cleat according to the present invention can be simply and economically manufactured, requires only two bolts to be installed in the rear cover of the housing or a plate member fixed thereto, and can be set in place with a reduced number of operations, so as to be easily performed by a robot on an automated assembly line. Indeed, with particular reference to figure 2, after the push-button 10 has been set in position, the contact clamping plate need only be pressed slightly to engage the notch 30 in the groove 17 of the shank, then the bolts 13, 14 are inserted into the holes 18, 19 and two welds 16 need to be formed, for example by laser.

Fig. 5 schematically shows an embodiment of a multi-functional contact jaw for a housing comprising two push buttons 10a, 10b, which, as previously mentioned, are connected to two strip springs 22a, 22b, with the difference that the base of each jaw is connected to form a ring 31 comprising two radial extensions 32, 33 in which mounting holes 18, 19 are drilled. The bent ends 28a, 28b are of course pressed against different contact areas of the printed circuit 7.

The same arrangement is of course possible for more than two buttons and/or with a non-circular housing.

Claims (7)

1. -a multi-functional contact jaw (20) associated with at least one push-button (10), said push-button (10) having a head (11) and comprising a plate (5) and a metal grid (15), a shank (12) passing through the median portion of a casing closed by at least one rear cover (3), characterized in that: said contact jaw (20) is formed by a single piece comprising a plane metal base (21) substantially parallel to the back cover (3) and provided with means (18, 19) for its fixation inside the casing and on one side of the stem (12) and at least one elastic strip spring (22) substantially perpendicular to the base (21), which extends beyond the stem (12) and follows a portion of the inner periphery of the intermediate portion (2), said strip spring (22) having a first pre-stressed portion (23, 24) placed opposite the stem (12) and having a notch (30) cooperating with a groove (17), the groove (17) being arranged close to the end of the stem (12) to form the key member and the return spring in the unloaded position, and a second portion (25, 26, 27) having a greater elasticity than the first portion, and its end (28) closes a contact (8) of the printed circuit (7) with a force less than the force required to actuate the button (10).

2. The contact cleat of claim 1 wherein: the second part (26, 27) of the strip spring (22) has a cross section which is smaller than the cross section of the first part (23, 24).

3. The contact cleat of claim 2 wherein: the second part (26, 27) of the strip spring (22) has a width which is smaller than the width of the first part (23, 24).

4. The contact cleat of claim 1 wherein: the means for fixing the base are formed by two openings (18, 19) in which two bolts (13, 14) are inserted, one end of which is fixed to the back cover (3) or to a plate (5) parallel to the back cover (3) and is carried out by two welds on the grid (15).

5. The contact cleat of claim 1 wherein: the base (21) also includes a pad (29) bent out of the plane of the housing to form a contact on the printed circuit (7).

6. The contact cleat of claim 1 wherein: the base (21) conforms to the entire periphery of the intermediate portion and comprises a plurality of resilient springs (22a, 22b) arranged to face the same number of buttons (10a, 10 b).

7. Timepiece, characterized in that it comprises at least one multi-functional contact bridge (20) according to any one of claims 1 to 6.