Metal working – Method of mechanical manufacture – Electrical device making
Patent
1986-11-05
1988-09-27
Echols, P. W.
Metal working
Method of mechanical manufacture
Electrical device making
200 86R, 264263, 264511, H01H 1104
Patent
active
047731559
DESCRIPTION:
BRIEF SUMMARY
CROSS REFERENCE TO RELATED APPLICATIONS
This application is a national phase application corresponding to PCT/DE86/00079 filed 3 Mar. 1986 and based, in turn, on a German national application No. P35 07922.3 filed 6 Mar. 1985 under the International Convention.
FIELD OF THE INVENTION
The invention relates to a mat switch with two opposite, mutually movable, particularly flexible and electrically conductible contact surfaces, separated by electrically-insulated spacers, elastically deformable in vertical direction and defining contact windows between them, having projecting contact bosses in the area of the contact windows on at least one of the two contact surfaces with respect to the opposite contact surface, these bosses consisting of bulges in the contact surface, whereby the distance between these contact bosses and the opposite contact surface, e.g. the opposing contact bosses, is not greater than the elastic range of spring action of the the spacers.
BACKGROUND OF THE INVENTION
Such mat switches are used, for instance, as protection devices for closers. When an object, located in the path of contact closing edges, is in contact with the mat switch, a closed path, similar to that of a turned-on switch is established, through which a safety measure, as a rule a disconnection of the drive for the closer, can be initiated. Such mats are also used as contact floor mats within the path of the closing edges, so that the drive can not be actuated, as long as a person stands on the contact floor mat.
A mat of this kind is known from the publication "THE SAE JOURNAL OF AUTOMOTIVE ENGINEERING" Vol. 79, No. 10, Oct. 1091, page 22 and serves there as a sensor indicating whether the seat of a vehicle is occupied or not. The contact surfaces consist of thin copper sheet, and the bulges are formed therein by impression. The shape-preserving rigidity of these sheets required by the impression results however in the need for relatively high forces in order to establish contact. In addition, the acting forces have to be distributed over a relatively large surface, in order to counteract the high shape-preserving rigidity of the contact surfaces, to bring them closer to each other and establish contact between them. If the mat switch is subjected only to a local pressure, no contact may be made as a result of these forces, while when bigger forces are applied there can result a permanent deformation of the contact surface.
A similar mat switch is also known from the German open application DE-OS No. 24 18 856. However, there the bulges within the range of the contact windows are formed in the opposite direction, so that in the window area the contact surfaces are separated from each other by a greater distance than in the area of the spacers. When pressure is applied, the bulges reverse themselves elastically towards the opposite contact surface and establish the contact this way. But, even in this case, considerable forces are required, since the contact surfaces must have a sufficient shape-preserving rigidity. Also, the mat switch must be sealed in a synthetic-material sheathing, for the purpose of avoiding the penetration of dirt or water.
In the mat switch known from the German published specification DE AS No. 11 69 001, the contact surfaces are flat and parallel when not subjected to a load. The upper surface to be exposed to the load is made of heavy sheet metal, resistant to any bending, while the lower contact surface is made of relatively light sheet metal. The lower contact surface is provided at its bottom with base projections, arranged in the area of the contact windows. When the mat switch is subjected to load, the base projections push the lower contact surface upwardly, in the area of the contact windows and the contact is established. Here too, considerable forces are required in order to initiate the switching operation, because deformation of the entire lower contact surface required, due to the rigidity of the upper contact surface.
Finally, a process for manufacturing a mat switch is known
REFERENCES:
patent: 3654407 (1972-04-01), Kepner et al.
patent: 3718791 (1973-02-01), Szablowski
patent: 3722086 (1973-03-01), Wikkerink et al.
patent: 3812313 (1974-05-01), Wolf
patent: 3821500 (1974-06-01), Newman
patent: 4172216 (1979-10-01), O'Shea
The SAE Journal of Automotive Engineering, vol. 79, No. 10, Oct. 1971, pp. 22-23.
Dubno Herbert
Echols P. W.
Mayser GmbH & Co.
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