US 3824576 A
An alarm system consists of a touch-sensitive electronic circuit connected to the handle of a door by an electrical connection which is completed through the striker plate area and latch bolt.
Description (OCR text may contain errors)
United States Patent 1 91 v 1 1 ,824,576.-
Pioch 1 July 16, 1974 1 ALARM SYSTEM ACTIVATED BY TOUCH 1,122,010 12/1914 Lesko 200/6168 T 3,025,434 3/1962 Atkins CI al. 317/146 SENSITIVE DOOR KP'JOB IN RUSIQR 3,147,468 9/1964 Daniels 200/6168 x  Inventor: Robert J. Ploch, 3982 U op a 3,171,066 2/1965 Atkins 6161; 340/258 c x Clark Lake, Mich. 49234 3,197,588 7/1965 Baldwin et al. ZOO/61.68 3,200,306 8/1965 Atkins et al 340/258 0 x  Flledi 1972 3,492,542 1/1970 340/258 c x 21 APPL NO; 2 1 132 3,514,557 5/1970 Jette, Jr. 200/6168 X Primary Examiner-James R. Scott  Attorney, Agent, or Firm-Harness, Dickey & Pierce  Int. Cl. G08b 13/00, l-lOlh 35/00  Field of Search 200/6162, 61.65, 61.67, [57 ABSTRACT 200/6168; 317/146, DIG. 2; 340/63, 258 C,
278 274; 307/38, 39, 86, 116 An alarm system conslsts of a touch-sensmve electronic circuit connected to the handle of a door by an  References Cited electrical connection which is completed through the UNITED STATES PATENTS striker plate area and latch bolt.
1,075,955 10/1913 Wright et al 200/6168 1 Claim, 1 Drawing Figure ALARM SYSTEM ACTIVATED BY TOUCH SENSITIVE DOOR KNOB INTRUSIOR BACKGROUND OF THE INVENTION Various systems have been proposed to warn the occupants of a building or other enclosure of the presence of persons who have come onto the premises or into the enclosure. Some such systems are arranged to sense the unauthorized opening of a door or window. Other systems sense the presence of an intruder who has already entered the enclosure itself, or who has entered a controlled space guarded by surveillance-type sensing equipment.
If an intruder contemplating criminal activity has already entered the enclosure, however, the limited and critical time available for protective action is not only reduced, but the would-be criminal is already psychologically committed, having made as illegal entry, and having placed himself in a position from which it may be much more difficult physically as well as psychologically to retreat.
The overall aim of the present invention is to provide an improved system which provides more effective protection for the occupants and a more effective deterrent to a criminal than prior art systems of the indicated varieties, and wherein a warning device is activated by the act of grasping the knob or handle of a door A more specific object of the invention is to provide improved, simple and reliable apparatus of the indicated variety which is simple to install, effectively concealed, and difficult for a criminal to disable.
Other objects and advantages will become apparent upon further consideration of the present disclosure in its entirety.
BRIEF DESCRIPTION OF THE FIGURE OF DRAWING The single FIGURE of drawing is a somewhat diagrammatic sectional view taken horizontally through a door and door jamb, showing the installation of the input connection member employed in my improved alarm system, and also indicating somewhat diagrammatically an alarm and control assembly connected thereto.
DETAILED DESCRIPTION OF PREFERRED FORM OF THE INVENTION As indicated hereinabove, l preferably employ a system which is responsive to the touching of or close presence to an electrically conductive component such as a door handle so that the capacitive or inductive effect of the human bodywill trigger, through a touchresponsive circuit arrangement, desired alarm apparatus. The touch-responsive circuitry is so connected to the metallic knob or handle of a door that it will respond to anyone grasping the handle if the door is closed, even if a glove (or other insulating layer) is interposed between the hand and the knob or handle of a person grasping it, to trigger desired warning or indicating devices.
As shown in the drawing, the installation is arranged to coact with a conventional hinged door, generally designated 10, having a latch/lock assembly, generally designated 12, which includes a latch bolt 14 retractable by turning either the external knob 15 or the internal knob 16. The external knob is formed of metal, as
is the shaft 18 which, when turned by the knob, retracts the latch bolt 14, an electrically conductive connection thus being provided between the knob 15 and bolt 14. When the door is closed the projected latch bolt extends through an opening 20 in a striker plate 22 mounted on the door jamb 24. The door jamb may be backed by conventional 2X4 framing and stud members 25, 26 as is usual in wood framing. These are of course concealed by lath or wallboard 28 inside the building and by external sheathing 30. These structural components, as well as the door and lock and latching means may be of conventional construction, or may be varied. In themselves, they do not form any part of the present invention.
Means are provided whereby, when the door is closed, an electrical connection is provided between the door knob 15 and remote apparatus which is designed to sense grasping of the knob. Such electrical connection is completed through the striker plate 22. Although it would be possible to connect a wire such as the lead wire 33 directly to the striker plate, relying upon the electrical connection between the striker, bolt, lock mechanism, shaft and knob, I preferably provide a more positive electrical connection between the bolt 14 and the electrical conductor 33 leading to the triggering circuit, since the bolt may not always be in firm contact with the striker plate.
An electrical connection member 35 is provided, consisting of a cylindrical body adapted to be pushed into a hole 36 drilled by the installer in the framing and stud members 25, 26. Drilling is preferably accomplished by first removing the striker plate, and if necessary, enlarging the bolt clearance hole 38 in the jamb 24 behind the striker plate bolt hole 20, and then drilling the hole 36 completely through both of the members 25, 26 in registry with the shot position of the bolt. The connector body 35 is provided near its outer end with a laterally projecting abutment collar 40 which limits the extent to which it can be pushed into the hole 36. It fits relatively tightly in the hole 36, and carries on its outer end a flexible metallic spring contact element 42, which may be formed of a phosphor bronze strip, positioned to be effectively engaged by the bolt. The lead wire 33 is electrically connected to the contact element 42. One or more washers may be placed under the abutment 40, to position the contact strip 42 for properengagement by the latch bolt 14.
The lead 33 extends to any desired location, which may be either remote from or close to the door, inside the house or enclosure. As shown in the drawing a box 45 is provided in the wall and may contain the touchresponsive circuitry (not shown) as well as an alarm device, and a shutoff switch. The alarm device may be an electronic squealer, siren, bell or other noise-making device, the sound of which is rendered audible through louvers as 46 in the face plate 48 which covers the box on the inside wall. The toggle knob of a shutoff switch is also illustrated at 50.
Suitable touch-responsive triggering systems, control switches, relays, alarm bells and the like are well known in the art and need not be described herein. Such trig- I gering systems are disclosed in the following U.S. pa-
tents, among others: Atkins et al. U.S. Pat. No. 3,025,434 granted Mar. 13, 1962; Roberts U.S. Pat. No. 3,103,003 granted Sept. 3, 1963; Atkins 3,200,306 granted Aug. 10, 1965; Atkins U.S. Pat. No. 3,569,728 granted Mar. 9, 1971; and Bellis U.S. Pat. No.
3 3,666,988 granted May 30, 1972. Such triggeringsysterns are adapted to trip a relay, which, as is well known in the intrusion alarm art, may be effective not only to operate an audible warning device, as suggested previously herein, but to turn on lights, operate police alerting systems, recorders, or the like. Such systems also frequently include a time delay circuit, which enables authorized personnel to enter the premises and shut off the system before the alarm is activated, or an outside key-operated and/or concealed shutoff switch may be provided to permit authorized entry without activating the alarm. Such variations, again, being well known, will not require specific description. They are often varied in accordance with the needs and desires of the users of the system. I
With my improved system, the presence of a person is indicated before entry has been effected. Except as to authorized personnel (who will know how to prevent activation of the system), the grasping of the knob or handle of a closed outside door of a home is, in itself, an act of a suspicious character, of which the occupants should be apprised.
For places where public access is permitted, this improved warning system may be used merely as an announcing device, during business hours, and used as an alarm at other times. For example, a relatively soft bell or light may be activated by the triggering circuit, during business hours, to call attention to the entrance of a customer, while at nighttime and at times other than business hours, a loud alarm and/or police alerting system, which is disconnected during business hours, can be activated and operatively connected to the triggering'circuit to protect the premises.
This Detailed Description of Preferred Form of the Invention, and the accompanying drawing, have been furnished in compliance with the statutory requirement to set forth the best mode contemplated by the inventor of carrying out the invention. The prior portions consisting of the Abstract of the Disclosure and the Background of the Invention are furnished without prejudice to comply with administrative requirements of the Patent Office. I
What is claimed is:
1. An alarm system adapted to indicate the touching of the door handle of a swinging door having a door handle and a latch bolt whichis electrically connected to and mechanically operable by the door handle whereby the latch bolt is movable into and out of me and alarm when the door is closed.