Anti-carjacking device triggered by a switch in the seat belt latch

• US 5,438,311 A
• Filed: 02/05/1993
• Issued: 08/01/1995
• Est. Priority Date: 02/05/1993
• Status: Expired due to Term

• Current Assignee: Donald W. Lane Sr
• Original Assignee: Donald W. Lane Sr
• Inventors: Lane, Donald W. Sr.
• Primary Examiner(s): Groody, James J.
• Assistant Examiner(s): Flynn, Nathan J.
• Application Number:
  US08/014,133
• Time in Patent Office: 907 Days
• Field of Search: 340/426, 340/430, 340/438, 307/10.1, 307/10.2, 307/10.3, 180/286, 180/287, 180/289
• US Class Current: 340/426.11
• CPC Class Codes: B60R 25/10 actuating a signalling device

Abstract

An anti-carjacking circuit for disabling a motor vehicle after the driver of the vehicle has been unwillingly forced to exit the vehicle. The circuit includes: a sensor for sensing the exit of the driver, as by detecting the opening of the seat belt or, alternatively, the opening of the seat belt together with the driver'"'"'s door; a latching memory such as a relay, responsive to the sensor, for recording the exit of the driver from the vehicle while the motor of the vehicle is powered; a delay circuit such as a comparator sensing the voltage across a capacitor charged by a resistor, responsive to the latching memory and startable thereby, for indicating the passage of a predetermined period of time after the starting thereof; and a disabling circuit, such as a relay, responsive to the indication by the delay circuit of the passage of the predetermined delay period, for disabling the motor of the motor vehicle as by breaking the ignition coil'"'"'s circuit and possibly sounding an alarm. A hidden reset switch may also be included for resetting the circuit in case it is accidentally tripped, as might happen if the driver forgot to turn the engine off before removing the seat belt.

Claims

1. An anti-carjacking circuit for disabling a motor vehicle'"'"'s motor after the driver of the motor vehicle has been unwillingly forced to exit the motor vehicle, said motor vehicle including a driver'"'"'s seat belt latch, said circuit being responsive to electrical power being applied to the motor vehicle'"'"'s motor through normal operation of said motor vehicle and said circuit not requiring separate actuation of any alarm-enabling switch, said circuit comprising:

(a) sensing means for sensing the exit of the driver from the motor vehicle, said sensing means comprising a seat belt switch means for sensing the opening of the seat belt latch;

(b) latching memory means, responsive to said sensing means, for recording the exit of the driver from the motor vehicle while the motor of the motor vehicle is powered;

(c) delay means, responsive to said latching memory means and startable thereby, for indicating the passage of a predetermined period of time after the starting thereof; and

(d) disabling means, responsive to the indication by the delay means of the passage of said predetermined period of time, for disabling the motor of the motor vehicle.

2. The circuit as recited in claim 1, in which the motor vehicle further includes a driver'"'"'s door, and said sensing means further comprises a driver'"'"'s door switch means for sensing the opening of the driver'"'"'s door, and in which said seat belt switch means and said driver'"'"'s door switch means are operably interconnected so that said sensing means senses the exit of the driver only when the seat belt latch is opened and the driver'"'"'s door is opened.

3. An anti-carjacking circuit for disabling a motor vehicle'"'"'s motor after the driver of the motor vehicle has been unwillingly forced to exit the motor vehicle, said motor vehicle including an ignition coil interposed between a switched voltage and a ground potential and further including a seat belt latch, said circuit being responsive to the application of said switched voltage to said ignition coil through normal operation of said motor vehicle and said circuit not requiring separate actuation of any alarm-enabling switch, said circuit comprising:

(a) sensing means for sensing the exit of the driver from the motor vehicle, said sensing means comprising a seat belt switch means for sensing the opening of the seat belt latch;

(b) latching memory means, responsive to stud sensing means, for recording the exit of the driver from the motor vehicle while the motor of the motor vehicle is powered;

(c) delay means, responsive to said latching memory means and startable thereby, for indicating the passage of a predetermined period of time after the starting thereof, said delay means comprising;

i. a delay resistor having a first end arid a second end and being connectable at said first end to a charging voltage;

ii. a delay capacitor having a first end connected to said second end of said delay resistor and having a second end connected to a ground potential; and

iii. comparator means for detecting the charging by the charging voltage of said delay capacitor past a predetermined threshold voltage and for indicating the passage of said predetermined period of time when said delay capacitor has charged past said predetermined threshold voltage; and

(d) disabling means, responsive to the indication by the delay means of the passage of said predetermined period of time, for disabling the motor of the motor vehicle and for activating an alarm when the motor of the motor vehicle is disabled by said disabling means, said disabling means comprising interruption contact means, connectable in series with the ignition coil, for interrupting the flow of current through the ignition coil.

4. The circuit as recited in claim 3, in which said circuit additionally comprises hidden reset means for resetting said latching memory means by the driver so that said recorded exit of the driver becomes unrecorded.

5. The circuit as recited in claim 3, in which the motor vehicle further includes a driver'"'"'s door, and said sensing means further comprises a driver'"'"'s door switch means for sensing the opening of the driver'"'"'s door, and in which said seat belt switch means and said driver'"'"'s door switch means are operably interconnected so that said sensing means senses the exit of the driver only when the seat belt latch is opened and the driver'"'"'s door is opened.