GB2126012A - Snap-acting electric contact - Google Patents

Abstract

A snap-acting electric contact is cut from metal sheet and comprises a central planar portion 1 which is extended to opposite sides by two wings 2 forming a predetermined angle with the plane of portion 1, and providing for a snap-acting deformation of the contact (into electrical contact with an underlying element 5) in response to pressure applied to its top. The ends of the con tact are provided with lugs 3 which can be soldered to a printed circuit 4. <IMAGE>

Description

SPECIFICATION Snap-acting electric contact The present invention relates to an electric contact exhibiting a tactile effect of sudden operation.

Such contacts generally have a convex shape, such that when a force is applied centrally, for example by means of a finger, the contact changes over into a concave shape to establish a contact with a point of an electric circuit placed below, on a perpendicular axis through the centre.

Such a convex shape does not permit long travels, moreover if it is made of plastics material, it is necessary to cover the internal surface with a conducting material which is liable to deteriorate after being operated numerous times. In order to avoid this disadvantage, it is possible to make such a contact from a metal sheet which has to be pressed to obtain the convex shape, which increases the price.

In accordance with this invention, there is provided an electric contact exhibiting a tactile effect of sudden operation, comprising a planar upper central portion extended laterally by two wings forming a predetermined angle with the plane of the central portion, and co-operating with a conducting element disposed below said central portion, to establish an electric circuit between said contact and said element upon a snap-deformation of said contact.

An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a contact; Figure 2 is a longitudinal section of that contact; Figure 3 is a diagram to illustrate the deformation characteristic of the contact; Figures 4, 5 and 6 are sectional views showing this deformation; and Figure 7 is a longitudinal section of the contact mounted on a support plate.

The contact is cut out of a metal sheet and comprises (Figure 1) a planar upper central portion 1 which is extended laterally by two wings 2 forming a predetermined acute angle a, equal to about 20 +10 (this tolerance may vary depending on the metal used), with the plane of the central portion 1: the wings provided for a snap-action of the contact upon pressing its portion 1. Longitudinally, the central portion 1 is extended by two lugs 3 (Figure 2) bent at right angles in relation to said central portion and intended for soldering the contact to its support 4 (Figure 7).

A metal disc 5 is itself soldered to the support 4 at right angles to the centre line through the contact; it co-operates with this to establish the electric circuit at the moment of snapping.

For heavy currents being switched, the disc 5 is connected to the positive pole of the circuit and the contact to the negative pole in order to direct the metal transfer, which is inevitable on interrupting the current, from the disc to the contact blade. Thus the technical characteristics of this blade will not be impaired in time.

The contact works in the following manner: during the first portion C1 of its travel (Figure 3), which represents about 20% of its total travel C, the contact works in flexion (Figures 4 and 5) until it reaches the point E which is its point of spontaneous snapping. Having passed this point, the contact is suddenly deformed and falls as far as its total travel C (Figure 6). Said travel C is determined by the height of the disc 5, that H (Figure 2) of the lugs 3 and the length L of the contact. By selecting these three parameters, it is therefore possible to obtain the contact travel desired. Similarly, it is possible to select the contact force by selecting the angle a of the wing, the width 12 of the body, the length L of the contact and the thickness e of the material.

Furthermore, in the case of multiplex matrix keyboards, the constitution of the contact enables it to be used as a conductor between the two lugs 3 soldered to the printed circuit which enables the crossing of tracks to be avoided.

Claims

1. An electric contact exhibiting a tactile effect of sudden operation, comprising a planar upper central portion extended laterally by two wings forming a predetermined angle with the plane of the central portion, and co-operating with a conducting element disposed below said central portion, to establish an electric circuit between said contact and said element upon a snapdeformation of said contact.

2. A contact as claimed in Claim 1, in which the planar central portion is extended longitudinally by two lugs which bent at right angles to said central portion and rigidly connected to a support and electrically connected to a pole of an electric circuit to be switched.

3. A contact substantially as herein described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (3)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Snap-acting electric contact The present invention relates to an electric contact exhibiting a tactile effect of sudden operation. Such contacts generally have a convex shape, such that when a force is applied centrally, for example by means of a finger, the contact changes over into a concave shape to establish a contact with a point of an electric circuit placed below, on a perpendicular axis through the centre. Such a convex shape does not permit long travels, moreover if it is made of plastics material, it is necessary to cover the internal surface with a conducting material which is liable to deteriorate after being operated numerous times. In order to avoid this disadvantage, it is possible to make such a contact from a metal sheet which has to be pressed to obtain the convex shape, which increases the price. In accordance with this invention, there is provided an electric contact exhibiting a tactile effect of sudden operation, comprising a planar upper central portion extended laterally by two wings forming a predetermined angle with the plane of the central portion, and co-operating with a conducting element disposed below said central portion, to establish an electric circuit between said contact and said element upon a snap-deformation of said contact. An embodiment of this invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a cross-section of a contact; Figure 2 is a longitudinal section of that contact; Figure 3 is a diagram to illustrate the deformation characteristic of the contact; Figures 4, 5 and 6 are sectional views showing this deformation; and Figure 7 is a longitudinal section of the contact mounted on a support plate. The contact is cut out of a metal sheet and comprises (Figure 1) a planar upper central portion 1 which is extended laterally by two wings 2 forming a predetermined acute angle a, equal to about 20 +10 (this tolerance may vary depending on the metal used), with the plane of the central portion 1: the wings provided for a snap-action of the contact upon pressing its portion 1. Longitudinally, the central portion 1 is extended by two lugs 3 (Figure 2) bent at right angles in relation to said central portion and intended for soldering the contact to its support 4 (Figure 7). A metal disc 5 is itself soldered to the support 4 at right angles to the centre line through the contact; it co-operates with this to establish the electric circuit at the moment of snapping. For heavy currents being switched, the disc 5 is connected to the positive pole of the circuit and the contact to the negative pole in order to direct the metal transfer, which is inevitable on interrupting the current, from the disc to the contact blade. Thus the technical characteristics of this blade will not be impaired in time. The contact works in the following manner: during the first portion C1 of its travel (Figure 3), which represents about 20% of its total travel C, the contact works in flexion (Figures 4 and 5) until it reaches the point E which is its point of spontaneous snapping. Having passed this point, the contact is suddenly deformed and falls as far as its total travel C (Figure 6). Said travel C is determined by the height of the disc 5, that H (Figure 2) of the lugs 3 and the length L of the contact. By selecting these three parameters, it is therefore possible to obtain the contact travel desired. Similarly, it is possible to select the contact force by selecting the angle a of the wing, the width 12 of the body, the length L of the contact and the thickness e of the material. Furthermore, in the case of multiplex matrix keyboards, the constitution of the contact enables it to be used as a conductor between the two lugs 3 soldered to the printed circuit which enables the crossing of tracks to be avoided. Claims

1. An electric contact exhibiting a tactile effect of sudden operation, comprising a planar upper central portion extended laterally by two wings forming a predetermined angle with the plane of the central portion, and co-operating with a conducting element disposed below said central portion, to establish an electric circuit between said contact and said element upon a snapdeformation of said contact.

2. A contact as claimed in Claim 1, in which the planar central portion is extended longitudinally by two lugs which bent at right angles to said central portion and rigidly connected to a support and electrically connected to a pole of an electric circuit to be switched.

3. A contact substantially as herein described with reference to the accompanying drawings.