Intrusion alarm system with automatic exit control and misset indicator

• US 4,683,460 A
• Filed: 05/22/1985
• Issued: 07/28/1987
• Est. Priority Date: 05/25/1984
• Status: Expired due to Fees

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Nakatsugawa, Norihiko
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US06/736,949
• Time in Patent Office: 797 Days
• Field of Search: 340/545, 340/501, 340/528
• US Class Current: 340/545.1
• CPC Class Codes: G08B 13/00 Burglar, theft or intruder alarms
• CPC Class Codes: G08B 25/008 Alarm setting and unsetting, i.e. arming or disarming of the security system

Abstract

An intrusion alarm system with an automatic exit control and a misset indicator which informs that someone has trespassed by opening a door during the resident'"'"'s absence. This system comprises a sequential circuit which is enabled by mode selection by the resident at his/her going out and which stores the door'"'"'s opening and closing signal produced as an output signal of a door open/closed detection circuit upon a second door opening, a misset alarm device which generates an alarm if the opening of the door is not detected within a predetermined time after the "Absent" mode is placed, and a timer circuit which is operated by the output signal of the sequential circuit and at the time-up to generate alarms. The sequential circuit can be cleared or disabled when the resident comes home and generation of an alarm is then prevented.

Claims

1. An intrusion alarm system comprising:

a mode selection circuit which selects a "Present" mode which represents the presence of a resident in a house, building, room or the like and an "Absent" mode which represents the absence of the resident from the house, building, room or the like, said mode selection circuit being set by the resident;

a door open/closed detection circuit which detects a door'"'"'s being in an open state or a closed state;

a sequential circuit which operates while said mode selection circuit is set in the "Absent" mode and stores signals representative of the door being opened and then closed according to said door open/closed detection circuit, said sequential circuit detecting that the door was opened for a second time after the mode selection circuit is set in the "absent" mode, and producing an output signal upon the detection of the second door opening;

a misset alarm device which generates an alarm if an opening of the door is not detected by said door open/closed detection circuit within a predetermined time after said mode selection circuit is placed in the "Absent" mode;

a timer circuit which starts counting upon said second door opening detected by said sequential circuit and produces an output signal upon expiration of a predetermined time as counted from the second door opening; and

an automatic information device which informs a security center of the detection of a trespasser when the output signal of the sequential circuit and the output signal of the timer circuit are both present.

2. The system according to claim 1, in which the sequential circuit comprises a first flip-flop circuit which is enabled when said mode selection circuit is in the "Absent" mode, and which changes its output state when the state of the door is changed from closed to open, and a second flip-flop circuit which changes its output state in response to the change of said first flip-flop circuit.

3. The system according to claim 1, in which the mode selection circuit comprises a manual switch circuit.

4. The system according to claim 1, in which the door open/closed detection circuit comprises a switch operated synchronously with the opening and closing of the door.

5. The system according to claim 1, in which the first and second flip-flop circuits are D-type flip-flop circuits whose negative output terminals are connected to D input terminals, respectively.

6. The system according to claim 1, in which the misset alarm device outputs a sound produced by an oscillator which forms a part of the timer circuit.