Communications: directive radio wave systems and devices (e.g. – Return signal controls external device – Radar mounted on and controls land vehicle
Reexamination Certificate
2001-12-19
2003-10-07
Gregory, Bernarr E. (Department: 3662)
Communications: directive radio wave systems and devices (e.g.,
Return signal controls external device
Radar mounted on and controls land vehicle
C342S027000, C342S028000, C342S175000, C343S704000, C343S711000, C343S872000, C343S873000
Reexamination Certificate
active
06630901
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a motor vehicle radar system.
BACKGROUND OF THE INVENTION
Motor vehicle radar systems are used, for example, in the context of a vehicle automatic speed control for detecting vehicles traveling ahead. One system is also termed Adaptive Cruise Control (ACC). In order to influence the electromagnetic waves used and thus also to protect the radar system from atmospheric conditions, a body is usually located in the beam path of the electromagnetic waves. Often this body is a component of a housing that surrounds a motor vehicle radar system of this type.
BACKGROUND INFORMATION
In German Patent No. 197 36 089, a metal plate lens is described, which is used for focusing or dispersing electromagnetic waves. The metal plate lens described is used preferably in a motor vehicle radar system. German Patent No. 197 36 089, is based on the consideration that, in the context of a radar system for automatic distance warning in a motor vehicle, specific conditions of use result in covering deposits, especially of snow or slush, building up on the lens. As a result of deposits of this type, electromagnetic waves passing through the lens are substantially dampened, which can ultimately lead to the total failure of the radar system. To improve the metal plate lens with regard to the aforementioned difficulties, it is proposed that, in at least one of the metal plates, there is a contact which can supply a heating current to the metal plate. In this context, the aforementioned metal plate can be connected in an electrically conductive manner to further metal plates of the lens, so that a supplied heating current also flows through the further metal plates. The aforementioned metal plate and the further metal plates can be connected to each other in series, in parallel, or in another switchable combination. So that the metal plate lens can also simultaneously function as a weather-proof covering for the actual motor vehicle radar system, the space between the metal plates of the metal plate lens is filled with a solid or foam dielectric. To increase the heating power, the metal plates to which a heating current can be supplied have a partial area which has an increased specific ohmic resistance in comparison to copper. This specific ohmic resistance increases the power loss, which results in greater heating power and therefore in a more powerful heating of the antenna lens.
From German Patent No. 196 44 164, a motor vehicle radar system is known that has at least one transmitting/receiving element for transmitting and/or receiving electromagnetic waves, a lens-shaped dielectric body being disposed in the beam path of the at least one transmitting/receiving element for focusing or dispersing the electromagnetic waves. The lens-shaped dialectic body, which also protects the transmitting/receiving element from atmospheric conditions, has an arrangement made of electrically conductive printed circuit traces, whose width, at a maximum, constitutes a tenth-wave, and whose distances from each other, at a minimum, constitute a quarter-wave, lambda designating the free-space wavelength of the electromagnetic waves. The electrically conductive printed circuit traces, in this context, are arranged so as to be predominantly perpendicular to the polarization direction of the electromagnetic waves. The arrangement composed of electrically conductive printed circuit traces, in accordance with the desired application, can be disposed on the inner side of the dielectric body, i.e., the side that is facing the transmitting/receiving elements, the outer side, or even within the dielectric body. If a heating current flows through the electrically conductive arrangement, the dielectric body can in this manner be freed from deposits such as ice, snow, or slush. Similarly, using a heating current, the dielectric body can be dried or can be kept dry. Furthermore, it is disclosed that the possibility exists to subdivide the electrically conductive arrangement into at least two components, that are separated from each other. In this constellation, if the arrangement composed of electrically conductive printed circuit traces is situated on the outer side of the dielectric body, it is possible, by measuring the capacitance between the two separated components of the arrangement, to arrive at conclusions as to a so-called loss angle tan &dgr; of the coating material. In other words, it is possible to establish a contamination of the dielectric body. As a function of this established contamination, or of an established dirt covering, a heating current, which flows through the electrically conductive arrangement, can be switched on. On the other hand, by being subdivided into at least two areas, the heating power can be varied, for example, for a rapid heating up of an ice-covered lens using high heating power and subsequently keeping the lens free using reduced heating power. From German Patent No. 196 44 164, it is also known that the electrical printed circuit traces, in a ceramic body, are applied using a known thick-film technology, whereas in bodies made of plastic, cost-effective methods, that are also known, can be used for imprinting the electrical printed circuit traces.
German Published Patent Application No. 197 24 320 discloses a method for manufacturing a heatable antenna lens. A heatable antenna lens made of a dielectric body is described, which contains within it an arrangement made of electrical printed circuit traces. In this context, the arrangement made of electrically conductive traces is situated as close as possible to the outer surface of the lens to be heated, as a result of which there is a reduction in the heating power by applying the energy closely underneath the surface to be heated. In addition, accelerated heating-up behavior results from this. It is also described that it is possible to achieve an efficient adjustability of the heating power as a result of the fact that wires are used that have a desired resistance behavior. This can be, for example, a resistance wire.
Both German Patent No. 197 36 089, and German Patent No. 196 44 164 as well as German Published Patent Application No. 197 24 320 describe various possibilities for freeing a motor vehicle radar system from coatings of ice, snow, or slush. The two first cited documents disclose the possibility of regulating the heating power as a result of the fact that either the metal plates are connected to each other in various combinations or at least two electrically conductive arrangements are combined for regulating the heating power accordingly. German Published Patent Application No. 197 24 320, on the other hand, discloses only the possibility of adjusting the heating power using wires having a desired resistance behavior. In the aforementioned systems, at lower external temperatures and at higher driving speeds, the result is a powerful cooling of the surface due to the convection at the surface of the radar system. In this context, depending on the ambient conditions and the driving speed, it is possible that despite a switched-on maximum heating power, temperatures at the surface of the radar system can be close to the freezing point.
SUMMARY OF THE INVENTION
The object of the present invention lies in indicating a motor vehicle radar system that is better adapted to the ambient conditions. This objective is achieved as a result of the fact that in a motor vehicle radar system having at least one sensor-radiation transparent body for focusing the sensor beam and/or a radome without the desired focusing in the beam path, at least one arrangement made of electrical printed circuit traces being disposed in the area of the sensor-radiation transparent body and/or the radome, the arrangement being appropriate at least for heating the sensor-radiation transparent body and/or the radome, it being possible to supply electrical power to the electrical printed circuit traces, power control of the supplied electrical power being carried out as a function of the operating states and ambien
Lucas Bernhard
Mayer Hermann
Peveling Wolfgang
Winter Klaus
Gregory Bernarr E.
Kenyon & Kenyon
Robert & Bosch GmbH
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