Communications: radio wave antennas – Antennas – Antenna components
Reexamination Certificate
1999-06-24
2001-07-24
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Antenna components
C343S753000, C343S91100R
Reexamination Certificate
active
06266028
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an antenna lens for a distance sensor, there being recessed on one side of a lens base element grooves into which are placed electrically conductive traces which are encapsulated into the grooves. Distance sensors can be used in particular for motor vehicles, for example in the context of an automatic distance warning system, a pre-crash detection device, or an adaptive vehicle speed control system.
BACKGROUND INFORMATION
German Patent Application No. 96 44 164 describes a dielectric element which is located in the beam path of the radar system and possesses at least one arrangement made up of electrically conductive traces. The arrangement is to be dimensioned and/or arranged such that its effect on the beam path of the electromagnetic waves is negligible. This is achieved by the fact that the arrangement has conductive traces whose width is no more than &lgr;/10 and whose spacings from one another are at least &lgr;/4, &lgr; denoting the free-space wavelength of the electromagnetic waves being used. The conductive traces themselves should extend largely perpendicular to the polarization plane of the radiated or received waves.
Also described is the possibility of dividing the electrically conductive arrangement into at least two portions separated from one another, so that the electrical resistance and capacitance between the two separate portions can be measured. These two variables contribute to the so-called loss angle tan &dgr; of the coating material, which allows conclusions to be drawn regarding the magnitude of any soiling or of a coating on the dielectric element.
Thick-film technology in the case of elements made of ceramic, and known printing methods in the case of plastic elements, are cited as possibilities for manufacturing the electrically conductive arrangement on the dielectric element.
Nothing is set forth in German Patent Application No. 1 96 44 164 regarding the manufacture of electrically conductive traces which run within a dielectric element.
German Patent Application No. 1 97 24 320 describes a heatable antenna lens made up of a dielectric element which possesses therein an arrangement of electrically conductive traces. The lens is configured such that the electrically conductive arrangement does not lie in one plane, and such that the electrically conductive arrangement is; arranged close to the convex external surface of the lens. Attachment of the heating contacts is accomplished through holes in the lens base element. The material indicated for the lens is preferably a thermoplastic such as polycarbonate or polyethylene.
A two-stage injection process is set forth for manufacture of the lens. In this, a lens base element with a groove preferably of continuously meandering shape is first injection-molded. A resistance wire is placed into this continuous groove. This intermediate assembly is then injection-coated with a surface layer, preferably made of the same material as the lens.
A disadvantage of German Patent Application No. 197 24 320 is that the electrically conductive traces that are laid in place can slip during the second injection-molding operation. If the intended position of the electrically conductive traces were to change under the injection-molding pressure, subsequent overheating and damage to the plastic, and possibly to the wire, at those points would be possible.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide an antenna lens for a distance sensor into which electrically conductive traces are introduced in such a way that their position within the antenna lens is exactly defined.
According to the present invention, the electrically conductive traces are placed into grooves in the lens base element, passed over the edge of the lens base element, and held in their position with fastening elements.
An advantage of the antenna lens according to the present invention is that the electrically conductive traces are held in their position by the fastening elements in such a way that when the lens base element is injection-coated, no further slippage is possible. The danger of later overheating and damage to the plastic and possibly to the electrically conductive traces, due to incorrect positioning of the electrically conductive traces, is thus eliminated.
Advantageously, fastening elements in the form of projections on the outer edge of the lens base element, fastening elements on the side of the lens base element facing away from the grooves, and clamping elements on the side of the lens base element facing away from the grooves, are present. These fastening elements and clamping elements securely hold and clamp the electrically conductive traces in the desired position. If the various fastening elements are located at different distances from the center of the lens base element, this non-intersecting placement of the electrically conductive traces prevents any electrical short-circuit due to mutual contact.
REFERENCES:
patent: 1812695 (1931-06-01), Harms
patent: 3188642 (1965-06-01), Bock et al.
patent: 3673606 (1972-06-01), Maune
patent: 3972043 (1976-07-01), Lotus
patent: 4318108 (1982-03-01), Yukl
patent: 4757323 (1988-07-01), Duret et al.
patent: 5764199 (1998-06-01), Ricardi
patent: 196 44 164 (1998-04-01), None
patent: 197 24 320 (1998-12-01), None
Lucas Bernhard
Schmidt Ewald
Dinh Trinh Vo
Kenyon & Kenyon
Robert & Bosch GmbH
Wong Don
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