EP0777918B1 - Microwave signal switch - Google Patents

Abstract

A microwave signal switch with a metal housing containing an electrically conductive part and two electrically conductive pads each having a contact surface for contacting a facing surface on said part, said electrically conductive part being movable from a closed position in which it engages and electrically interconnects the contact surfaces of both pads, and an open position in which it is spaced apart from said contact surfaces. At least one of the contact surfaces (5) and/or the surface (9) of said electrically conductive part (3) are provided with projections (6) comprising, in a cross-sectional plane perpendicular to the contact surface, an acute-angled cross-section with a vertex angle (Υ) of less than 110° and a radius of curvature of less than 0.05 mm.

Description

The present invention relates to a switch for signals. microwave.

We already know for example from JP-A-5075302 such switches which include, inside a metal cavity, two pads electrically conductors, each comprising a contact face, and a part electrically conductive movable between a closed position in which it rests on the contact faces of the pads and connects these electrically and an open position in which it is set back from said contact faces.

These switches are used to build relays electric for microwave signals, for which they properly perform their closing and opening function microwave circuit, even under operating conditions difficult, for example in an environment polluted by impurities.

Indeed, even in the event of poor electrical contact between the electrically conductive part and the contact faces of the pads, the microwave signal is transmitted, at least by capacitive coupling, between the contact faces of the pads and the part electrically conductive.

On the other hand, for low frequencies, even for direct current, quality electrical contact is required to make a good electrical connection between the studs and the part electrically conductive.

However, these switches are often used to convey not only microwave signals, but also currents direct, for example bias currents, or currents medium or low frequency AC, for example currents feed.

In these circumstances, the switch operates satisfactory, whatever its conditions of use, for which is microwave signals but faults in operation may appear with regard to the currents of medium or low frequency, or direct currents.

This occasional malfunction of the switch is all the more annoying since it is not reproducible.

It is therefore difficult to determine precisely which would be the conditions to be respected to guarantee an operation reliable switch, for a wide range of current frequencies transmitted.

It is also known from GB-A-579 365, in an arrangement of electrical contact used for high frequency coaxial conductors, to provide undulations the peripheral surface of a tubular element sliding axially in another tubular element. During the relative movement of the elements, the vertices of undulations, which extend parallel to the axis, rub against the facing surface and wear out quickly. After a reduced number of cycles, the desired tight contact effect no longer takes place.

Friction wear would be even faster if the tops of the ripples had a sharp edge.

The present invention aims to provide a switch for microwave signals, also usable for low frequency signals and continuous signals which solves the problems mentioned above and in particular has a very high reliability, whatever are the operating conditions to which it is subject.

The subject of the present invention is a switch for microwave and continuous signals including inside a box metallic, an electrically conductive part and two studs electrically conductive, each having a contact face with a surface facing said piece, said piece electrically conductive being movable between a closed position in which it rests on the contact faces of the two studs and connects them electrically and an open position in which it is set back from said contact faces, characterized by the fact that at least one of the contact faces and / or the surface of said electrically conductive part are provided with protrusions comprising, according to at least one section plane perpendicular to the face contact, a sharp-edged section with an angle at the top less than 110 ° and a radius of curvature less than 0.05 mm.

The device according to the invention allows, by reducing the bearing surface between the electrically conductive part and the faces contact pads, increase contact pressure.

So when the electrically conductive piece arrives in contact with the contact faces of the studs, the sharp edge of the protrusions breaks possible films of impurities which may have deposited on the electrically conductive part or on top of protuberances.

The harmful action of impurities in the environment of switch can therefore be avoided.

Likewise, when the switch is subjected to strong temperature variations, vaporization cycles occur, condensation and solidification of the water present in the ambient air, which causes the formation of frost films on the faces of contact of the pads and on the electrically conductive part.

The mechanical action of the protrusions again allows break the frost film and ensure good electrical contact between the pads and the electrically conductive part.

According to the invention, the grooves which separate two adjacent protrusions of the contact face of the pads allow to evacuate the impurities broken by the tops of the protuberances.

Another advantage provided by the presence of protrusions on the contact faces of the pads comes from the fact that said protrusions are all contact zones between the studs and the electrically conductive part, which limits the risks false contacts.

In a preferred embodiment of the invention, the protrusions extend along parallel section lines constant.

According to a first variant, these lines are rectilinear.

According to a second variant, these lines are circular and concentric.

According to a third variant, these lines are in a spiral.

In these second and third variants, the face of contact of the studs may include a peripheral crown on which extend the circular or spiral lines while a recess is formed in the central part delimited by said crown of the contact face of the stud.

The invention applies equally well to switches in which the contact face of the pads is provided with protuberances, while the surface of the electrically conductive part facing contact faces of the pads is smooth or provided with protrusions having the geometric characteristics defined above, that switches in which the contact face of the pads is smooth while the surface of the electrically conductive part facing contact faces of the pads is provided with said protrusions.

• la figure 1 est une vue en coupe d'un commutateur selon un mode de réalisation de l'invention,
• la figure 2 est une vue en perspective d'un plot du commutateur de la figure 1,
• la figure 3 est une vue en coupe selon III-III de la figure 2,
• la figure 4 est une vue rapprochée des protubérances du plot de la figure 3,
• la figure 5 est une vue de détail de la partie 5 de la figure 4,
• les figures 6 à 9 sont des vues de dessus de plots comportant des protubérances de différents types, et
• la figure 10 est une vue en perspective d'une pièce électriquement conductrice d'un commutateur selon la figure 1.

In order to better understand the invention, we will now describe embodiments, given by way of non-limiting examples, with reference to the accompanying drawing in which:

• FIG. 1 is a sectional view of a switch according to an embodiment of the invention,
• FIG. 2 is a perspective view of a pad of the switch in FIG. 1,
• FIG. 3 is a sectional view along III-III of FIG. 2,
• FIG. 4 is a close-up view of the protuberances of the pad of FIG. 3,
• FIG. 5 is a detailed view of part 5 of FIG. 4,
• FIGS. 6 to 9 are top views of studs comprising protuberances of different types, and
• FIG. 10 is a perspective view of an electrically conductive part of a switch according to FIG. 1.

The switch of Figure 1 has, inside a box 1 electrically conductive and earthed, two pads 2 electrically conductive, each connected to a terminal of a circuit electric, and an electrically conductive elongated part 3, is here in the form of a metal blade carried by a piston 4, axially movable as indicated by the double arrow.

Due to the movements of the piston 4, the metal blade 3 is likely to assume a closed position, shown on the drawing, in which it rests on the end faces 5 pads 2, called contact faces in the sense of the invention, and a open position in which it is set back from the studs 2, preferably bearing against the wall of the housing 1 of so as not to be able to play the role of an antenna which would transmit electrical signals from one pad to another by radiation.

The pads 2 of the switch of Figure 1 are circular and have protuberances 6 on their upper face 5 as visible in Figure 2.

These protrusions 6 are distributed over a crown peripheral 7 of the contact face 5 of the stud, a recess 8 being formed inside this crown 7 in the central part of the contact face of the stud.

In the example shown in Figures 2 and 3, the protrusions 6 extend along lines of constant section, these lines being circular and concentric.

In accordance with the invention, the protrusions 6 have, according to an axial section plane of the stud, an acute section clearly visible in Figure 4.

In the detail view of FIG. 5, the radius has been transferred curvature (r) and the opening angle  at the top of each protuberance.

In the example illustrated, the radius of curvature r is equal to 0.01 mm and the angle at the top is 75 °.

Other protuberance variants are shown in Figures 6 to 9.

In Figure 6, the protrusion lines extend radially with respect to the stud.

In FIG. 7, they extend parallel between they in a constant direction.

In FIG. 8, the protuberances result from a crossing of circular and concentric projecting lines and radial broken lines.

In FIG. 9, the protuberances result from a crossing of protruding straight lines extending in two constant directions perpendicular to each other.

According to the invention, the protrusions 6, which have have been described on the contact face 5 of each stud, can also be provided on the surface 9 of the part electrically conductor 3 opposite the contact faces 5 of the pads, as shown in Figure 10 where we see that the end of the part contact 3 is triangular in shape.

The geometry of the protrusions 6 must then present the same geometrical characteristics as those defined above for the protrusions provided on the contact face of the studs.

In this variant, the contact face of the pads can be smooth or also have protuberances.

It is understood that the embodiments which have just been described have no limiting character and that they can receive any desirable changes without going out for this the scope of the invention.

Claims (5)

1. Switch for hyperfrequency and continuous signals comprising, within a metal housing, an electrically conductive part and two electrically conductive studs each comprising a contact face with a surface facing said part, the said electrically conductive part being movable between a closed position in which it rests on the contact faces of the two studs and an open position in which it is withdrawn from the said contact faces, characterised in that at least one of the contact faces (5) and/or the surface (9) of said electrically conductive part (3) are provided with protuberances (6) comprising, according to at least one cross-section perpendicular to a contact face, a sharp-edged section having a peak angle () less than 110° and a radius of curvature (r) less than 0.05 mm.
2. Switch according to claim 1 characterised in that the protuberances (6) extend along parallel lines of constant section.
3. Switch according to claim 2 characterised in that the lines are straight.
4. Switch according to claim 2 characterised in that the lines are circular and concentric.
5. Switch according to claim 2 characterised in that the lines are spiral.

Images