Door alarm with infrared and capacitive sensors
First Claim
1. A door alarm for providing two separate discrete signals indicating approach of an individual to a door and touching of the door knob by the individual, comprising:
- a metallic door knob on said door;
a shaft connected to said door knob and a latch mechanism on said door;
insulating means for electrically insulating said door knob and said shaft from said door and said latch mechanism;
a key lock cylinder extending through a front face of said door knob;
a circular mounting ring on said front face of said door knob surrounding said key lock cylinder;
four infrared sensors spaced circumferentially at ninety degree intervals around said mounting ring;
first control means connected to said infrared sensors;
audible alarm means activated by said control means in response to approach of an individual to said door to provide a first signal;
a capacitive discharge sensor connected to said metallic door knob;
second control means connected to said capacitive discharge sensor; and
means connected to said second control means for providing a second signal in response to touching of said door knob by an individual.
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Accused Products
Abstract
An alarm system for providing separate discrete signals corresponding with the approach of an individual to a door and the touching of the door knob by the individual utilizes a combination of infrared sensors and a capacitive discharge sensor. The infrared sensors are mounted on a circular ring on the face of the door knob. The sensors are angled in different directions to detect individuals approaching from various directions. The door knob is composed of a metallic material and acts as an antenna of a capacitive discharge proximity sensor. The door knob is insulated by a sleeve from the rest of the door and latch structure. Approach of an individual is detected by the infrared sensors which activates a first alarm signal. When the individual reaches for and touches the door knob, a second different alarm is activated.
69 Citations
7 Claims
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1. A door alarm for providing two separate discrete signals indicating approach of an individual to a door and touching of the door knob by the individual, comprising:
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a metallic door knob on said door; a shaft connected to said door knob and a latch mechanism on said door; insulating means for electrically insulating said door knob and said shaft from said door and said latch mechanism; a key lock cylinder extending through a front face of said door knob; a circular mounting ring on said front face of said door knob surrounding said key lock cylinder; four infrared sensors spaced circumferentially at ninety degree intervals around said mounting ring; first control means connected to said infrared sensors; audible alarm means activated by said control means in response to approach of an individual to said door to provide a first signal; a capacitive discharge sensor connected to said metallic door knob; second control means connected to said capacitive discharge sensor; and means connected to said second control means for providing a second signal in response to touching of said door knob by an individual.
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2. A door alarm, comprising:
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door knob means; infrared sensor means on said door knob means for detecting approach of an individual remote from said door knob; and alarm means connected to said infrared sensor means activated by said approach of an individual.
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3. A door alarm, comprising:
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door knob means; sensor means on said door knob means for detecting approach of an individual remote from said door knob; said sensor means comprising at least one infrared sensor and a capacitive discharge sensor; and alarm means connected to said sensor means activated by said approach of an individual. - View Dependent Claims (4, 5, 6, 7)
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Specification