Electronic key reader

ES 2 199 891 T3

DESCRIPTION

Electronic key reader.

The present invention relates to improvements relating to readers for electronic keys.

In the field of access control, each authorized user has a badge equipped with an electronic device that, when powered by an external source, delivers a coded signal that allows, for example, the opening of a door, when it is recognized. by the reader.

The reader transmits the energy necessary for the operation of the badge by means of a self-inductance coupling, which means that the reader and the badge each incorporate an antenna that is in the form of a coil.

The reader is arranged outside the premises from which access is controlled, and means against acts of vandalism must be provided. Usually the reader is enclosed in a very sturdy metal box, fixed firmly against the exterior facade. The external face of this box has slits to allow the antenna flux to radiate outwards. In certain cases, the reader is recessed, and its front face is protected by a metal plate.

Experience has shown that, to be effective, the badge should be placed relatively close to the reader, which is explained by the fact that the metal box, or the plate, behaves like a loop traversed by the flux emitted by the antenna, which absorbs part of the energy emitted by the latter, transforming it into heat.

The present invention, which overcomes this drawback, is relevant because the box has a slit that extends from one of the edges of the box to substantially the center of the front face of the latter.

The present invention will be better understood by the description that follows, made with reference to the attached drawings by way of an indicative example only, in which:

Figure 1 is a perspective view of a known box;

Figure 2 is an elevation view of a box according to the invention;

Figure 3 is a top view of Figure

2;

Figure 4 is a view, analogous to Figure 2, showing an alternative embodiment.

With reference to Figure 1, it can be seen that the reader is enclosed in a metallic box 1, behind whose front face 2 the usual antenna schematized by means of the loop 3 has been arranged.

Openings 4 have been provided on face 2, to allow the flow emitted by loop 3 to escape. Experience has shown that only a small part of the energy radiated by loop 2 was received by the user's badge plate, needing to meet , the latter, relatively close to the reader.

This phenomenon is explained by the fact that the box behaves like a self-inductance loop, absorbing part of the flux emitted by antenna 3.

The present invention, which makes it possible to remedy the aforementioned drawback, is relevant since the box has a slit 5 that extends from the edge 2a of face 2, to the center of said face, the said slit extending over the lateral face 6 of the box to open onto its field 6a.

When the box is limited to a metal plate that covers the reader, which is embedded, the above-mentioned slit opens onto either side of said plate.

Experience has shown that the absorption effect resulting from the metal box was considerably reduced due solely to the presence of the slit 5 of Figure 2, in relation to the possibility that a user is recognized, even if he is located at a distance from the reader far superior to that which should have been previously.

Well understood, there is nothing that opposes the fact of providing on the front face of the reader, openings analogous to those referenced with 4.

The result of the invention can be improved with the provision of various slits such as those referenced with 7 in Figure 4.

Preferably, the end 5a of the slit 5 extends beyond the median line AB, joining the midpoints of the sides adjacent to it where said slit opens.