Abstract:
A wireless system that detects the presence of a child in a safety seat located in the passenger cabin of a vehicle includes a controller responsive to signals generated by sensors monitoring predefined functions of the vehicle, RFID tag device attached to the safety seat and RFID tag reader mounted in the cabin. The system generates control signals which activate an alarm, open the doors of the vehicle and roll down windows if the child is left in the safety seat of an unattended vehicle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation of U.S. patent application Ser. No. 11/194,179, filed on Aug. 1, 2005, now U.S. Pat. No. 7,321,306 and entitled WIRELESS SYSTEM TO DETECT PRESENCE OF CHILD IN A BABY CAR SEAT, which claims priority to Provisional Application Ser. No. 60/635,371, filed Dec. 10, 2004. 

   BACKGROUND OF THE INVENTION 
   A. Field of the Invention 
   The invention relates to systems for detecting the presence of occupants of an automobile. In particular, the invention relates to systems that detect the presence of a child in a child&#39;s seat without other passengers and the automobile is not in an operational mode. In this case, corrective action is taken to minimize injuries to the child. 
   B. Prior Art 
   Most, if not all, jurisdictions within the United States of America require infants and children of certain age to be strapped into a child&#39;s seat when the automobile is in motion. Failure to do so is an infraction of the law and could result in the operator paying a fine for the infraction. Even though this law protects infants and children under certain conditions, it could also cause injuries or even death to the infant and children it is suppose to protect. One of the conditions occurs when an operator parks the vehicle and forgets to remove the occupant from the child seat. There have been reports in the press that the operator leaves an occupant in the baby seat, the temperature soars or drops and as a result the child or infant suffers injuries. In fact, there have been reports of children and/or infants dying from high temperatures. 
   To prevent this unintended result, the prior art has provided systems that detect the presence of occupants in an infant seats of unattended vehicles and sound an alarm on such detection. U.S. Pat. Nos. 5,949,340 and 6,714,132 are examples of such prior art systems. Even though the systems provided in these patents work well for intended purposes, the child&#39;s seat in these systems requires some type of power which is derived from the vehicle, in which the child&#39;s seat is mounted. To obtain power from the vehicle the child&#39;s seat is usually wired to the electrical system of the vehicle. This requirement imposes unnecessary restrictions which limits portability of child&#39;s seat. In other words, if the child&#39;s seat is wired to the vehicle electrical system as is required by U.S. Pat. No. 5,949,340, the seat can only be used with the vehicle to which it is wired. 
   In view of the prior art limitations, there is a need to provide a more efficient detection system that makes the child&#39;s seat portable so that it can be used in different vehicles. 
   SUMMARY OF THE INVENTION 
   The system of the present invention is implemented with Radio Frequency Identification, hereafter RFID, technology. The RFID technology is packaged into a RFID tag and a RFID tag reader. The electrical structure of the RFID tag includes an antenna coupled by a switch to the tag electronics. The tag reader includes an electromagnetic wave (EMW) transmit antenna, RFID code receives antenna, associated electronic circuits and an interface to couple the tag reader to the vehicle electronics. The RFID tag is attached to the child&#39;s seat also called the safety seat and the tag reader is placed inside the cabin of the vehicle in spaced relation to the RFID tag. Communication between the tag reader and the tag is wireless. 
   The switch in the RFID tag is pressure sensitive so that the electrical continuity between antenna and associated electrical circuit occurs when a child is placed in the safety seat. Electrical discontinuity occurs when the child is removed from the safety seat. When the RFID tag reader is enabled by the automobile central controller (with the appropriate conditions which will be described subsequently) it will emit electromagnetic wave energy to energize the RFID tag device which in term transmits its RFID code to the RFID tag reader. The RFID tag reader then relays the identified car-seat status information back to the automobile central controller which takes predefined actions to minimize injury to the occupant of the safety seat. 
   The cost of the RFID components have been steadily decreasing, so the cost of the detection and corrective system will be relatively low. 
   The RFID system generates its own power, so none is needed from the vehicle power system. 
   Because the RFID tag is mounted on the safety seat and makes wireless connection with the tag reader, the safety seat is portable and can be moved from one vehicle to the next. Of course, each of the vehicles must be fitted with a compatible RFID tag reader. 
   These benefits, advantages and others are made available to users of the present invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a schematic of a vehicle in which the RFID system of the present invention is deployed. 
       FIG. 2  shows a schematic of the safety seat containing the RFID tag device and the expanded-view of the switchable transmit/receive antenna system of the RFID tag device according to teaching of the present invention. 
       FIG. 2A  shows a block diagram of the RFID tag reader according to teaching of the present invention. 
       FIG. 3  shows a schematic of the RFID tag according to teachings of the present invention. 
       FIG. 4  shows schematic for the control system according to teachings of the present invention. 
       FIG. 5  shows a flow chart of the process or program used in the control unit of  FIG. 4 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a pictorial schematic of a vehicle  100  armed with a child safety protection system according to the teachings of the present invention. The child safety protection system monitors occupancy of baby seat  102  and takes corrective action, such as sounding an alarm, unlocking doors or rolling down windows if a child is left in the vehicle. The child safety protection system includes a RFID tag reader  104  deployed in the roof of the vehicle. RFID tag device  106  is mounted to the baby seat  102 . Because RFID tag device  106  is mounted to the baby seat  102  it may be transported and used in different vehicles provided with a compatible RFID tag reader  104 . It should also be noted that the RFID tag reader can be mounted in other locations in the cabin other than the roof. This is possible because RFID tag reader  104  need not be in line with RFID tag device  106  in order to exchange information. It is only require for the RFID tag reader to be within the close proximity around the RFID tag device. 
     FIG. 2  shows a schematic of the details of the baby seat  102  and the RFID tag device  106  according to the teachings of the present invention. It should be noted that throughout the different views of the drawings common devices or components are identified by like numerals. It should be noted that throughout this document safety seat and baby seat are used interchangeably. Also, shown in  FIG. 2  is an expanded internal structure view of the RFID device  106  with its transmit/receive antenna  302 , antenna switch  304 , and RF circuit  300 . When the antenna switch  304  is closed, electromagnetic wave energy from the RFID tag reader can induce electric current through the transmit/receive antenna  302  to power up the RF circuit  300 . Once being powered up, the RF circuit  300  transmits its embedded RFID code through the same transmit/receive antenna  302  for the RFID reader to read. On identifying the receive RFID code, the RFID reader relays the car safety seat status to the Automobile Central Controller (describe subsequently) to take one or all the corrective actions mentioned herein. 
     FIG. 2A  shows a block diagram of the RFID tag reader  104 . It includes a Reader Control Unit  200 , an Electromagnetic Wave (EMW) Emitter  202 , a RFID Code Receiver  204 , an EMW Transmit Antenna  206 , and a RFID Code Receive Antenna  208 . During operation, when the right conditions (describe subsequently) are met, the automobile central controller sends an RFID tag reader enable signal via interface  210  to the Reader Control Unit  200  to enable the EMW Emitter  202  to emit EMW through the EMW Transmit Antenna  206 . If antenna switch  304  ( FIGS. 2 and 3 ) is closed, the RFID tag device  106  is energized. Once energized and powered up, the RFID tag device  106  transmits is embedded RFID code as radio signal into the surrounding for the RFID tag reader  104  to read. Once the RFID Code Receiver  204  receives the RFID code through the RFID Code Receive Antenna  208  and identified the correct code, it sends a RFID identity signal to the Reader Control Unit  200  which in term sends the corresponding car-seat status via interface  212  to the Automobile Central Controller (describe subsequently) to take one or all the corrective actions mentioned herein. The function performed by each of the components shown in  FIG. 2A  are evident from the above description. 
     FIG. 3  shows a schematic for RFID tag device  106  which is substantially the same as the schematic shown in  FIG. 2 . RFID tag device  106  includes RFID tag device circuit  300  which is an off the shelf item detail of which will not be given. When a child or infant is sitting in safety seat  102  switch  304  closes and RFID tag device  106  is configured to receive electromagnetic wave energy from RFID tag reader  104  and in turn transmits its ID to said tag reader  104 . 
     FIG. 4  shows in block diagram of the overall RFID child safety seat system  400 . The diagram shows interaction between RFID tag reader  104  and components in the automobile in which the system is mounted. The system includes the automobile main control unit  402 . This main control unit could be a computer in which an application program is executed to carry out the function necessary to implement the child protection according to the teachings of the present invention. 
   As stated previously, communication between RFID tag device  106  and RFID tag reader  104  is wireless. The automobile main control unit  402  is connected over a separate transmission channel to the car ignition switch (SW) sensor  404 , car door switch sensor  406 , auto alarm  408 , light alarm  410 , car window open switch  412  and RFID reader  104 . For completeness, the RFID Tag  106  is shown mounted in spaced relationship to the RFID reader. The car switch sensor  404  senses the state of the vehicle ignition switch and indicates whether the switch is on or off. Car door switch sensor  404  senses the state of the doors in the vehicle and forward signal to the main control unit indicating whether the doors are closed or open. The RFID tag reader  104  receives enabling signal from main control unit  402 . On receiving this signal the RFID reader  104  is now in the state to emit electromagnetic wave energy to enable and communicate with the RFID tag device  106 . The conditions which causes the main control unit  402  to issue a read enable signal to RFID tag reader  104  will be discussed subsequently. 
   Still referring to  FIG. 4  the auto alarm  408 , light alarm  410  and the car window open switch  412  are all activated when the control unit  402  determines that a child is left in the infant seat and the car ignition switch is off, the car doors are closed and the RFID reader is returning a positive child engage or child present signal. 
     FIG. 5  shows a flow chart for an application program which can be executed in the main control unit  402  to carry out the steps necessary to implement the child safety protection according to the teachings of the present invention. The program enters at block  502  and descends into block  504  whereat sensor  404  is interrogated to determine the state of the ignition switch. If the car&#39;s ignition switch is on, the program loops; otherwise, (i.e. car&#39;s ignition off) the program exits along the yes path into block  506  whereat the main control unit  402  outputs the reader enabled signal to enable the RFID tag reader  104  to emit electromagnetic wave energy to its proximity neighborhood. The reader emitted electromagnetic wave energy is collected by external switchable antenna  302  of the RFID device  106 . If a child was in the safety seat switch  304  would have been closed and the RFID tag device circuit  300  would have been energized by the received signal. As a consequence a radio RFID tag code is transmitted from the RFID tag device  106 . The RFID tag code includes the identity (tag number) of the tag device. On receiving the identity tag code the RFID reader returns a signal to the main control unit  402 . 
   Referring again to  FIG. 5  if at block  508  the return control signal indicates the child seat is not engaged (empty) the program exits along the no path and loops. If the signal in  508  indicates that the child seat is engaged (occupied) the program descends along the yes path into block  510  whereat the program waits for a preset time interval and then descends into block  512 . In block  512  the program tests if the child seat is engaged. As stated above this is done by the signal that is returned from the RFID reader to control unit  402 . If the safety seat is empty the program exits along the no path and loops. If the safety seat is occupied the program exits along the yes path into block  514 . In block  514  the controller takes corrective actions, such as activating an audio alarm, light alarm, move windows to down position etc. The program then descends into block  516  whereat it checks if the child is in the seat. If the child is not in the seat the program exits along the no path and loop. If the child is in the seat the program descends into block  518  whereat an alarm is activated and the program loops back to block  516  to repeat the action previously discussed. 
   As stated above the purpose of this invention is to detect when a child is left in a safety seat while the vehicle is unattended and to take corrective action to prevent injury to the child. The switch  304  ( FIG. 3 ) of the RFID tag device  106  can be a pressure switch which is closed by the weight of the child in the safety seat. An alternative approach would be to close the switch when the safety buckle of the safety seat is engaged, as is required by law to protect the child. Of course, other techniques for closing the switch  304  can be implemented by one skilled in the art without deviating from the spirit or scope of the invention. 
   So long as switch  304  is open, the RFID tag device is not in a state to transmit or receive information from the RFID tag reader. Switch  304  closes when an object, such as a child, is in the safety seat  102 . With the tag device  106  armed (i.e. switch  304  is closed) if the RFID reader  104  is enabled it will send out electromagnetic waves (EM waves) waves to energize to the antenna  302  of the RFID tag device. As stated above the RFID reader is enabled if the vehicle ignition switch is in the off state. With the antenna switch of the RFID tag device closed, the EM waves from the RFID reader are received as induced energy in the RFID tag device and Power up the RFID tag device. Once the RFID tag device is energized it can transmit its identifying code (ID) to the same external antenna  302  from which it has received the energizing signals. Once the RFID tag code is received by the RFID reader it indicates that an object, such as a child, is in the safety seat. The RFID reader then outputs reader return signals to the main control unit. The main control unit uses the signals to take corrective action as set forth above. 
   Even though the present invention has been described with references to specific embodiment this should not be construed as limitation in the scope of the invention as claimed herein. It is within the skills of one skilled in the art to make obvious adjustments and changes without deviating from the scope and spirit of the claimed invention.