Magnetic door alarm with resettable delay

• US 5,434,556 A
• Filed: 01/12/1994
• Issued: 07/18/1995
• Est. Priority Date: 01/12/1994
• Status: Expired due to Fees

• Current Assignee: Daniel J. Donohoo
• Original Assignee: Daniel J. Donohoo
• Inventors: Donohoo, Daniel J.
• Primary Examiner(s): SWANN III, GLEN R
• Application Number:
  US08/180,439
• Time in Patent Office: 552 Days
• Field of Search: 340/547, 340/546, 340/545, 340/636, 340/528
• US Class Current: 340/547
• CPC Class Codes: G08B 13/08 by opening, e.g. of door, of window, of drawer, of shutter, of curtain, of blind
• CPC Class Codes: G08B 21/086 by monitoring a perimeter outside the body of the water

Abstract

A battery alarm system that is capable of recognizing when a child has opened a door by utilizing self contained electronic circuitry with a switch mounted out of reach of the child. If a child opens the door, the horn sounds. If a taller person opens the door, he can prevent the sounding of the alarm by pressing the switch either before or after the door is opened and then closing the door within a preset time. The preset time period may be extended by pressing the button. If the horn has sounded and the button is pressed, closing the door will shut off the horn. The door can also be opened and closed and the switch pressed all within a preset time without the horn being sounded. These features avoid the horn being unnecessarily sounded. When the battery energy is depleted, the horn emits a chirping sound for several weeks. The electronic circuitry allows for very low power drain and permits the battery to last for over a year under normal operating conditions. The switch, horn, and electronic circuitry are mounted near a door with leads from the electronic circuitry to a magnetic reed mounted on the door jam. The magnet that mounts to the door next to the reed switch activates and deactivates the reed switch.

Claims

1. An alarm system comprising

a proximity switch responsive to the opening of a door to produce an energizing signal;

a user actable switch;

an electrical power source;

an alarm means responsive to said energizing signal to provide a perceptible alarm signal; and

a timer and logic means for generating a plurality of time periods for disabling said alarm signal, one of which allows a time period after actuation of said user actuable switch before opening said door to activate said proximity switch during which activation of said alarm means is prevented for a predetermined period, another of which allows a time period after opening said door to activate said proximity switch during which activation of said user actuable switch prevents activation of said alarm means for a predetermined period, another of which allows an extension of the period during which activation of said alarm means is prevented after the alarm means has been energized and then disabled by said user actable switch, and another of which allows for an extension of the period during which activation of said alarm means is prevented before the alarm means is energized.

2. The alarm system of claim 1 further comprising

an electronic circuit comprised of a means to activate the alarm means if the lead between the electronic circuit and the proximity switch is interrupted.

3. The alarm system of claim 1 further comprising

an electronic circuit with a means to activate the alarm means with a chirping sound for an extended period of time when the energy of the power source is low.

4. The alarm system of claim 1 wherein the proximity switch comprises a magnetic reed switch.

5. The alarm system of claim 1 wherein the electrical power source comprises a battery.

6. An alarm system comprising:

a proximity switch responsive to the opening and closing of a door;

a user actable switch;

an electrical power source;

an alarm means responsive to an energizing signal to provide a perceptible alarm signal;

an electronic circuit comprised of a means to activate the alarm means if the proximity sensor senses the door'"'"'s opening without the actable switch'"'"'s being pressed within a predetermined length of time;

an electronic circuit comprised of a means to activate the alarm means if a lead between the electronic circuit and the proximity switch is interrupted;

an electronic circuit comprised of a means to extend the time period within which the door may be opened without activation of the alarm means by again pressing the actuable switch; and

an electronic circuit comprised of a means to allow the actuable switch to be pressed before or after the door is opened to avoid activation of the alarm means.

7. The alarm system of claim 6 further comprising

an electronic circuit with a means to activate the alarm means with a chirping sound for an extended period of time when the energy of the power source is low.

8. The alarm system of claim 6 wherein the proximity switch comprises a magnetic reed switch.

9. The alarm system of claim 6 wherein the electrical power source comprises a battery.