Communications: electrical – Condition responsive indicating system – Specific condition
Reexamination Certificate
1999-10-06
2001-12-11
Trieu, Van T. (Department: 2632)
Communications: electrical
Condition responsive indicating system
Specific condition
C340S562000, C340S438000
Reexamination Certificate
active
06329913
ABSTRACT:
A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.
BACKGROUND
The present invention is related to passenger detection systems, and in particular to passenger detection systems that can readily classify an attribute of a passenger of an automobile in which an air bag device is installed.
In general, air bag devices are used to ease the shock that a passenger experiences during an automobile collision, and as such must be stored in a stable condition in the automobile. Air bags are installed in front of the driver's and passenger's seats. Air bags may be installed in other locations.
In a typical air-bag system, the control system includes a control circuit that receives a signal from an electrical acceleration sensor (shock detection sensor), and transmits control signals to the gates of normally-open semiconductor switching elements. The switching elements are respectively connected in parallel paths between a system operating voltage and ground. Each path includes a safing sensor, a squib circuit and the switching element. The safing sensors are respectively mounted on the driver's seat and the front passenger seat, and each includes an acceleration detection mechanism that closes a normally-open switch in response to sudden acceleration (deceleration) of the respective seat. The squib circuits are connected to the gas sources of the air bag devices respectively mounted on the automobile in front of the driver's seat and the front passenger seat.
In operation, the air bag control system only deploys the driver-side and passenger side air bags when both of the safing sensors close, and when the electrical acceleration sensor closes. In particular, the acceleration detection mechanisms of the safing sensors close their respective normally-open switches in response to an acceleration that is relatively small in comparison to the acceleration necessary to close the electrical acceleration sensor. When closed, the safing sensors apply a high voltage signal to the control circuit and to first terminals of the squib circuits. The high voltage signals from the safing sensors cause the control circuit to enter into an operational mode. Next, the control circuit confirms that the automobile is in an accident based on the signal from the electrical acceleration sensor. If the electrical acceleration sensor also detects the acceleration, the control circuit transmits control signals that close the switching elements. As a result, current flows from the system operating voltage to ground through each of the squib circuits, thereby causing respective gas sources to deploy (inflate) the driver-side air bag and the passenger-side air bag. Once deployed, the air bags protect the driver and passenger from the shock of the collision.
Passenger-side air bags are typically designed to deploy in front of the torso of an adult passenger seated in the front passenger seat. When a rear facing infant seat (hereafter RFIS) is located on the front passenger seat, it is desirable for the passenger-side air bag not to deploy. It is also desirable for the passenger-side air bag not to deploy when a forward facing child seat (hereafter “FFCS”) is used.
Several passenger detection sensor types have been proposed for detecting a RFCS or an FFCS. Such proposed sensors include (1) a weight sensor and (2) an optics sensor and image processor. The weight sensor may incorrectly detect a heavy child, or fail to detect a light-weight adult. Further, if a heavy object (such as a bag of groceries) is placed on the seat, the air bag device may be needlessly deployed in an accident. The optics sensor is expensive and the processing equipment is complex.
Since airbags deploy forcefully and quickly, sensors for determining whether any passenger is in a desirable or undesirable location are desired. Such sensors may prevent injury. By avoiding deployment of the airbag when no passenger present, replacement costs may be avoided.
SUMMARY
The present invention is defined by the following claims, and nothing in this section should be taken as a limitation on those claims. By way of introduction, the preferred embodiment described below includes an inexpensive passenger detection system that accurately detects the presence of a passenger. The passenger detection system utilizes an oscillation circuit that causes an antenna electrode to emit an electric field that is disrupted by the electrical characteristics of an object placed on the seat. This disruption alters the current and phase of the signal in the antenna electrode. By comparing the current flowing in the antenna electrode and/or the difference between the phase of the signal in the antenna electrode and the oscillation circuit output signal with predetermined threshold values, it is possible to detect the presence of a passenger in a reliable and inexpensive manner.
In accordance with a first aspect, a vehicle passenger detection system for sensing a characteristic of a passenger in a passenger seating area is provided. A vehicle seat has an outer surface adjacent to the passenger seating area. A first electrode connects with a first portion of the vehicle seat a first distance from the outer surface. A second electrode connects with the first portion of the vehicle seat a second, different distance from the outer surface. The second electrode is adjacent to the first electrode.
In accordance with a second aspect, a vehicle passenger detection method for sensing a characteristic of a passenger in a passenger seating area is provided. An electric field is generated with at least one of (1) a first electrode connected with a first portion of a vehicle seat a first distance from an outer surface of the vehicle seat and (2) a second electrode connected with the first portion of the vehicle seat a second, different distance from the outer surface. The second electrode is adjacent to the first electrode. A signal from the first electrode is measured. A signal from the second electrode is measured.
In accordance with a third aspect, a vehicle passenger detection system for sensing a characteristic of a passenger in a passenger seating area is provided. A plurality of electrodes are arranged in at least two layers, where each layer is a different distance from the passenger seating area;. A controller is operable to receive information from the plurality of electrodes and is operable to determine the characteristic as a function of the information and the distance.
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Kirksey James Frederick
Shieh Shiuh-An
Shinmura Masanobu
Brinks Hofer Gilson & Lione
NEC Technologies, Inc.
Summerfield Craig A.
Trieu Van T.
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