Communications: electrical – Condition responsive indicating system – Specific condition
Patent
1996-03-13
1998-03-03
Mullen, Thomas
Communications: electrical
Condition responsive indicating system
Specific condition
128722, 3404571, G08B 1326
Patent
active
057240248
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to a device for detecting the presence of persons on seats, pursuant to the preamble of claim 1.
SUMMARY OF THE INVENTION
Such detecting devices have proven to be very important when there is a question of determining whether or not a seat in a vehicle is occupied. For example, this is necessary in connection with a passenger-side air bag, in order to determine whether or not a person is sitting in the front passenger seat, so as to avoid unnecessary triggering of the passenger-side air bag in case of an accident.
Likewise, it is necessary to determine the number of persons, not only in the front passenger seat, when there is a question of determining a certain vehicle occupation factor. This vehicle occupation factor relates to determining a calculation variable which indicates the distance which the vehicle has traveled with what number of persons. This is because it has turned out that as a rule, passenger cars are occupied only by one or two persons, and that any occupation number above this tends to be the exception.
It is now desirable to increase the occupation factor of passenger cars and for this purpose, it is necessary to first determine the number of persons riding in the motor vehicle, in a manner that is as resistant as possible to falsification.
Another problem consists of the desire to have a very accurate monitoring system to ensure that persons in the car have put on their safety belts. This can be desirable in case of accidents for reasons of insurance law.
Until now, it has only been known to detect the presence of persons by means of ultrasound sensors or infrared sensors, for example. These sensors, however, are not resistant to falsification and furthermore are inaccurate.
The invention is therefore based on the task of further developing a device of the type stated initially, in such a way that it is possible to detect the presence of persons on seats, for example in a motor vehicle, with a high level of security against falsification.
To accomplish the stated task, the invention is characterized by the technical theory of claim 1.
The significant characteristic of the invention is that only the presence of one person, in each instance or seat, is detected by means of one or more electrodes assigned to the person or seat, with a capacitative measurement being carried out on the person's body, using the electrodes. The body of the person to be detected is considered as the dielectric which is arranged between at least two electrodes, as a moving body. Flux lines develop between the electrodes and are modified by the moving body which is located in the flux line progression. This modification of the flux lines, caused by the movement of the person located in the field of action of the electrode, as well as by this person's breathing and/or heart beat (thorax changes), ensures an accurate measurement, which is furthermore resistant to falsification, of the presence of a person who is located between the electrodes.
For the arrangement of the electrodes to the body, there are a number of possibilities, all of which are supposed to be covered by the present invention.
In a first, preferred embodiment, it is provided that a first electrode is attached to the safety belt and rests against the front part of the person's body by being attached to the safety belt, while another electrode is attached to the seatback, forming a capacitor with the aforementioned first electrode.
In this connection, it is essential that the person's breathing is detected by means of changes in rhythm of the upper body, in the flux line progression of the two opposing electrodes.
The rhythmic expansion and contraction of the volume of the upper body resulting from breathing is therefore detected as a breathing signal and is evaluated accordingly. Since the parameters of human breathing are characteristic, this method is particularly secure against falsification, because a dog wearing a safety belt, for example, breathes differently than a human being wearing a
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Hupp Thomas
Kuehne Georg
Sonderegger Wilhelm
Mullen Thomas
Vos Verkehrs-Optimierungs-Systems GmbH & Co.
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