Communications: radio wave antennas – Antennas – High frequency type loops
Reexamination Certificate
1997-04-04
2001-10-23
Kim, Robert H. (Department: 2877)
Communications: radio wave antennas
Antennas
High frequency type loops
C343S741000, C343S743000, C343S744000, C343S866000, C340S572800, C340S008100
Reexamination Certificate
active
06307518
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an antenna configuration of an apparatus for detecting a child safety seat placed on a seat of a motor vehicle.
Especially in light of recent findings regarding the apparent dangers posed by airbags and the development and integration of systems which will ensure proper inflation of airbags (i.e. adjusted inflation force depending on the occupant and/or temporary disengagement of the tripping mechanism), it is most important to dependably determine various bits of information regarding the type and position of any occupant on each motor vehicle seat exposed to such airbags. The information is particularly important when a child safety seat is placed on the vehicle seat.
There has become known from German Patent DE 44 09 971 C2 one such apparatus, in which one transmitting antenna and one receiving antenna each are disposed in the vehicle seat. An electromagnetic exciter field is broadcast periodically via the transmitting antenna. A resonator/transponder of a child safety seat placed on the passenger seat alters the exciter field in a characteristic way. The exciter field altered by the resonator is picked up as a measurement field by the receiving antenna and evaluated by an evaluation circuit. If a single characteristic for a resonator is ascertained in the measurement field, then an output circuit of the apparatus generates a status signal that is supplied in particular to an airbag controller. The airbag controller can vary the tripping of an airbag disposed in front of the vehicle seat, or a side airbag disposed laterally of the seat, on the basis of the status signal output by the child safety seat detection apparatus. Optionally, airbag tripping can be prevented, to protect a child in the child safety seat from the force of the airbag as it inflates.
An improvement of the foregoing system is disclosed in European Patent Disclosure EP 0 708 002. According to that disclosure it is possible not only to detect whether a child safety seat is disposed on the vehicle seat but also to ascertain the orientation of the child safety seat on the vehicle seat: Either the child safety seat is disposed in the travel direction on the passenger seat with its backrest toward the vehicle seat, or the child safety seat is disposed counter to the driving direction on the passenger seat with its backrest toward the dashboard. When child safety seats face forward, it may still be allowable under some circumstances for the airbag to be tripped. To detect the child safety seat orientation, a child safety seat has two resonators, one in its left half and the other in its right half. Correspondingly there are one transmitting antenna and one receiving antenna each disposed in the left and right halves of the vehicle seat. Each resonator alters the exciter field generated by the transmitting antennas in a different way, so that by an evaluation of the measurement fields picked up from the receiving antennas it can be detected which resonator is disposed above which half of the vehicle seat.
With such an antenna configuration, however, a child safety seat placed in skewed orientation on the vehicle seat cannot be detected, for instance where one resonator is located directly above a gap between the transmitting and receiving antennas in the middle of the vehicle seat and the other resonator is on the periphery of the vehicle seat. If the child safety seat is skewed in this way or rotated, and especially if it is placed transversely across the vehicle seat, in which case both resonators are located above the gap, then tripping of the airbag is just as dangerous as in the rear-facing orientation. Yet even so, the child safety seat detection apparatus would still furnish a status signal indicating the absence of a child safety seat. There would be no hindrance to tripping the airbag at its full strength.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an antenna configuration of an apparatus for detecting a child safety seat placed on a seat of a motor vehicle, which overcomes the above-mentioned disadvantages of the prior art devices and methods of this general type and which allows detection and determination of the orientation of a child safety seat placed on the vehicle seat.
With the foregoing and other objects in view there is provided, in accordance with the invention, a combination of an apparatus for detecting a child safety seat placed on a seat of a motor vehicle and an antenna configuration integrated in the seat of the motor vehicle; the antenna configuration comprises:
a single loop-shaped transmitting antenna for transmitting an electromagnetic exciter field and two loop-shaped receiving antennas for receiving electromagnetic measurement fields.
In accordance with an added feature of the invention, the transmitting antenna has a diameter of at least 20 cm. In a rectangular (or square) loop, the diameter is defined as the shortest distance between sides.
In accordance with an additional feature of the invention, the vehicle seat has a left half and a right half as referred to a longitudinal axis of the vehicle, and wherein a first one of the receiving antennas is assigned to the left half of the vehicle seat and a second one of the receiving antennas is assigned to the right half of the vehicle seat.
In accordance with a further feature of the invention, the first and second receiving antennas overlap each other partly.
In accordance with another feature of the invention, the receiving antennas each have a single winding and are disposed in a single plane. The two receiving antennas may thereby define a gap therebetween, and the assembly includes an electrically conductive connection, across the gap, between the receiving antennas, the gap being bordered by a portion of each of the two receiving antennas and by the electrically conductive connection.
In accordance with again an added feature of the invention, there is provided a common substrate defining the single plane, and wherein the transmitting antenna has a single winding commonly disposed in the single plane with the receiving antennas, and wherein the transmitting antenna enclosed the receiving antennas. Preferably, the receiving antennas are surrounded by the transmitting antenna.
With the foregoing and other objects in view there is also provided, in accordance with the invention, an apparatus for detecting a child safety seat placed on a seat of a motor vehicle, comprising:
an antenna configuration integrated in a seat of a motor vehicle, the antenna configuration having a single loop transmitting antenna for transmitting an electromagnetic exciter field and two loop-shaped receiving antennas for receiving electromagnetic measurement fields;
a control device connected to the transmitting and receiving antennas for impressing the electromagnetic exciter field on the transmitting antenna, evaluating the measurement fields picked up by the receiving antennas, and generating a status signal as a function of the evaluated measurement fields.
In accordance with yet a further feature of the invention, the assembly also comprises one or several resonators secured to a child safety seat, and wherein the control device is programmed to generate a first status signal if neither receiving antennas detect in the respective measurement fields a signal that is typical for the presence of the resonator in the exciter field.
In accordance with yet another feature of the invention, the control device is programmed to generate a second status signal if at least one of the receiving antennas detect in a respective measurement field a signal that is typical for the presence of a single resonator in the exciter field.
In accordance with yet an additional feature of the invention, the control device evaluates an intensity of a first signal typical of a first resonator in the first measurement field and in the second measurement field, as well as an intensity of a second signal typical of a second resonator, both in the first measurement fie
Hamperl Reinhard
Hetzenecker Erwin
Pietsch Arnulf
Swart Marten
Zelger Christian
Greenberg Laurence A.
Kim Robert H.
Lauchman Layla
Lerner Herbert L.
Siemens Aktiengesellschaft
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