Abstract:
Occupant sensing system ( 12 ) for detecting the presence of an occupant within an automotive vehicle ( 10 ) includes a seat belt sensor ( 14 ) for detecting a buckled condition of the seat belt. An ignition sensor ( 24 ) generates an ignition-off signal. An indicator ( 30 ) is coupled to a controller ( 20 ), the seat belt sensor ( 22 ), and the ignition sensor ( 18 ). The controller controls the indicator in response to the seat belt buckled signal and ignition-off signal.

Description:
BACKGROUND OF INVENTION 
     The present invention relates generally to occupant sensing for automotive vehicles, and more particularly, to signaling the vehicle operator in response to a person being left in the vehicle. 
     Motor vehicles typically have a seat belt sensor that is used to detect the buckle being buckled or unbuckled. The sensing of the buckled or unbuckled state is performed after the ignition is started. An indicator is used to remind the vehicle operator to fasten the seat belt. Vehicles typically have only a driver seat belt sensor while the remaining seats do not have a seat belt sensor. 
     When transporting children, instances have been noted where children have been left in a vehicle for prolonged periods. This may happen especially for sleeping infants who make no noise. Thus the vehicle operator may forget about the infant. No means is currently provided for reminding a vehicle operator for the presence of other occupants. 
     Occupant sensing systems are known in which the temperature is detected and a motion detector is used to sense movement within the vehicle when the temperature is above an extreme temperature or below an extreme temperature. One problem with such a system is that at the time the vehicle operator leaves the vehicle the interior of the vehicle may be at a relatively safe temperature. The system notifies the driver in an extreme condition by sounding the horn. However, if the temperature subsequently rises or falls, the vehicle operator may be too far from the vehicle to hear the horn sounding. 
     It would therefore be desirable to provide an occupant sensing system that senses the presence of an occupant without the need for temperature sensing. 
     SUMMARY OF INVENTION 
     The present invention provides a system for detecting the presence of an occupant within a vehicle that has a seat belt sensor that generates a seat belt buckled signal and an ignition sensor generating an ignition-off signal. An indicator is also included in the system. 
     A controller is coupled to the seat belt sensor, the ignition sensor and the indicator. The controller controls the indicator in response to the seat belt buckled signal and the ignition-off signal. 
     In a further aspect of the invention, a method for detecting the presence of an occupant within an automotive vehicle comprises generating a seat belt buckled signal, generating an ignition-off signal, and activating an indicator in response to the seat belt buckled signal and the ignition-off signal. 
     One advantage of the present invention is that it is not dependent on the immediate interior or exterior temperature of the vehicle. 
     Another advantage of the invention is that various types of indicators include indication through a remote keyless device or cellular network. 
     Other advantages and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a partial cutaway view of an automotive vehicle having an occupant sensing system according to the present invention. 
     FIG. 2 is a block diagrammatic view of the sensing system of FIG.  1 . 
     FIG. 3 is a flow chart of the operation of the sensing system according to the present invention. 
    
    
     DETAILED DESCRIPTION 
     In the following figures, the same reference numerals will be used for the same components. 
     Referring now to FIG. 1, an automotive vehicle  10  has an occupant sensing system  12 . Occupant sensing system  12  is coupled to a seat belt  14  for a passenger seat  16  of automotive vehicle  10 . The occupant sensing system  12  is coupled to an ignition sensor  18 . Ignition sensor  18  may, for example, have an ignition switch commonly used in automotive vehicles. The ignition switch is used to receive a key which allows a lock cylinder to rotate and activate the switch. The switch has an on position and an off position generating an on signal and off signal, respectively. 
     Referring now to FIG. 2, system  12  is illustrated in further detail. System  12  has a controller  20  that has various inputs and outputs. Controller  12  is preferably a microprocessor-based system having common elements such as a CPU internal memory, and an IO bus. Controller  20  is coupled to a seat belt sensor  22  positioned within the seat belt or seat belt buckle of FIG.  1 . Seat belt sensor  22  generates a seat belt signal indicative of whether or not the seat belt is buckled. As shown, seat belt sensor  22  may be an electronic sensor or a continuity sensor such as a switch. In an unbuckled state, no signal is received while in a buckled state the switch is closed and an electrical signal is received at controller  20 . The ignition system may also be coupled to controller  20  through an ignition switch  24 . Ignition switch  24  generates an ignition-on signal when the ignition is on and an ignition-off signal when the ignition is off. The ignition-off signal may be the absence of an ignition-on signal. A timer  26  may also be coupled to controller  20 . Timer  26  may be used to time various events. Timer  26  may be used to count up, count down, and provide relative timing. One example of a use for timer  26 , as will be further described below, is for waiting a predetermined time from an event such as an ignition-off signal from ignition switch  24 . 
     A reminder button  28  may also be coupled to controller  20 . Reminder button  28  may enable and disable the occupant sensing system. For example, in some situations, child seats remain buckled in place and therefore the reminder button may be activated to disable the system once a reminder is generated. 
     Controller  20  may also be coupled to an indicator  30 . Indicator  30  may take many forms or combination of forms. Indicator  30  may, for example, issue a voice command  32 . Indicator may also be a horn or buzzer such as a car horn or buzzer  34 . Indicator  30  may also include flashing the interior lights  36  or exterior lights  38 . Controller  20  may also actuate a transmitter  40 . Transmitter  40  has an antenna  42  used to generate communication signals  44 A and  44 B to a remote keyless entry device  46  or a cellular phone  48  through respective antennas  50  and  52 . Cellular phone  48  may represent an actual cellular phone or other cellular device such as a paging device. Communication signal  44 B may also be routed through a cell tower (not illustrated). 
     Referring now to FIG. 3, the process begins in step  60 . In step  60 , controller determines whether the system is enabled. The system may automatically be enabled or may be enabled or disabled by the reminder button  28  described above. If the system is enabled, step  62  is executed. In step  62  if the ignition system is not on step  60  is re-executed. In step  62  if the ignition system is off as indicated by an ignition-off signal or the lack of an ignition-on signal, step  64  is executed. In step  64 , if the passenger seat belt is not latched, step  60  is re-executed. In step  64 , if the passenger seat belt is latched a time period may be waited in step  66 . Step  66  is an optional step. That is, a time period need not be waited. 
     After step  66 , an indicator signal generated by the controller is used to generate an indicator or actuate an indicator in step  68 . As mentioned above, various combinations of indicators may be used. Various voice.commands provided over the audio system of the vehicle may be generated to remind the vehicle operator that a seat belt is still fastened which indicates a person is still within the vehicle. Likewise, a horn  34  may be activated as well as interior lights  36  or exterior lights  38 . Of course, combinations of either may be used. A transmitter  40  may also be actuated to provide a reminder on a device such as a remote keyless entry device provided with a receiver or a cellular phone or paging device. 
     As can be seen, the present invention advantageously reminds the vehicle operator that another person is belted within the vehicle. 
     While particular embodiments of the invention have been shown and described, numerous variations and alternate embodiments will occur to those skilled in the art. Accordingly, it is intended that the invention be limited only in terms of the appended claims.