초록 ▼

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

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.

대표청구항 ▼

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 electri

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.