AUTOMOBILE THEFT ALARM WITH IGNITION CONTROLLED AUTOMATIC ARMING MEANS

• US 3,829,829 A
• Filed: 12/04/1972
• Issued: 08/13/1974
• Est. Priority Date: 01/12/1972
• Status: Expired due to Term

• Current Assignee: Harrison Systems Incorporated
• Original Assignee: Rudor M. Teich
• Inventors: Teich, Rudor M.
• Primary Examiner(s): Waring, Alvin H.
• Application Number:
  US05/311,939
• Time in Patent Office: 617 Days
• Field of Search: 340/63,64,65,276 307/1AT
• US Class Current: 340/430
• CPC Class Codes: B60R 2025/1013 Alarm systems characterised by the type of warning signal, e.g. visual, audible
• CPC Class Codes: B60R 25/1003 Alarm systems characterised by arm or disarm features
• CPC Class Codes: B60R 25/1004 Alarm systems characterised by the type of sensor, e.g. current sensing means using door lock sensors B60R25/1001

Abstract

A vehicle alarm system adapted to provide a pulsed actuation of an audible alarm upon unauthorized entry is provided with means to automatically rearm the circuit a predetermined interval after the ignition switch is turned off. The alarm is activated by a pulse generating circuit which is energized by a sensing circuit responsive to the rate of change of voltage at the vehicle battery terminals and is latched in its energized condition until the ignition switch is turned on. Means are provided to render the sensing circuit ineffective while the ignition switch is on and for a predetermined interval after it is turned off to allow the driver sufficient time to exit the vehicle. The pulse generating circuit is provided with an inherent initial time delay to provide the driver sufficient time to enter the vehicle and turn the ignition switch on. Means are provided for disarming the circuit when the ignition switch is turned to the accessory position and held in such position for a predetermined time interval, failing which the circuit will be automatically rearmed upon turning the ignition off. The practical effectiveness of the system is greatly enhanced by the requirement that the driver take positive action to disarm the alarm.

Claims

1. A control circuit having an output node and a control switch with at least three operative positions, comprising a voltage source, first and second lead lines, said control switch adapted in a first position to connect said voltage source to said first lead line, in a second position to connect said voltage source to said first and second lead lines, and in a third position to disconnect both said first and second lead lines from said voltage source, said output node being operatively connected to said first lead line, first switch means having a control and having its output circuit operatively connected between said voltage source and said first lead line, capacitive storage means operatively connected to said control terminal of said first switch means, means operatively connecting said capacitive storage means to said first lead line whereby said capacitive storage means is charged during a predetermined time interval when said control switch is in said first position, and second switch means having a control terminal and having its output circuit operatively connected to said control terminal of said first switch means in parallel with said capacitive storage means and adapted when closed to shunt said capacitive storage means, said control terminal of said second switch means being operatively connected to said second lead line, thereby preventing said capacitive storage means from being charged when said control switch is in said second position, said first switch means being adapted when said control switch is moved from said first position to said third position after said predetermined interval in said first position, to latchingly connect said output node to said voltage source.

2. The control circuit of claim 1, further comprising a resistor operatively connected between said first lead line and said capacitive storage means whereby said predetermined interval is defined by the time constant of said resistor and said capacitive storage means.

3. The control circuit of claim 1, wherein said output node comprises the input to a disarm circuit for a vehicle alarm system and wherein said control switch comprises the ignition switch of the vehicle, said first position comprising the accessory position, said second position comprising the start position and said third position comprising the off position.