US 2281193 A
Description (OCR text may contain errors)
April 28, 1942- c. HOLLINGSWORTH v 2,281,193
BUHGLAR ALARM Filed sept. 4, 1941 Patented Apr. 28, 1942 UNITED STATES PATENT OFFICE BURGLAR ALARM Campbell Hollingsworth, New York, N. Y. Application September 4, 1941, Serial No. 409,567
This invention relates to burglar alarms and more especially to burglar alarms of the type including a phonograph player electrically connected in circuit with a switch, so that when the switch is closed by the opening of a closure, the phonograph is set in operation to give an audible signal intended to put the burglar to flight.
An important object of my invention is to provide an improved type of switch of compact and eflicient construction designed to be inserted in a small opening provided in the door or window frame or casement, and normally held in break position by the closed door or window, but releasable upon opening said door or window to snap to make position and complete the burglar alarm circuit.
Another object of the invention is to provide a burglar alarm comprising a few simple parts and capable of being quickly and cheaply installed in buildings or on vehicles by persons f having only ordinary mechanical ability.
Other objects and advantages will be apparent from the following detailed description of a preferred embodiment of my invention, reference being had to the annexed drawing in which:
Figure l shows the general wiring layout of a burglar alarm system including a trip switch and a phonograph player mechanism;
Figure 2 shows the trip switch with one side of the enclosing box broken away for greater clearness; and
Figure 3 is a cross-sectional view of the trip switch taken on the line 3-3 of Fig. 2.
In Fig. 1 of the drawing is conventionally illustrated a window I adapted to be raised and lowered within a Casement 2. A portion of one side of the easement is broken away to show a trip switch 3 associated therewith and connected in circuit with a pair of conductors Il, 4a, including a source of current C and leading between the switch and a small electric motor 5. The electric motor is provided with a gear 6 upon its armature shaft, and this gear meshes with a companion gear 'I secured upon an end of a worm 8. The
Worm forms part of a phonograph-operating mechanism, here simply represented by va worm wheel 9 extending axially outward from one end of a cylinder I0 upon which is mounted a composition or steel phonograph record I I. A needle I2 connected with the usual sound reproducing diaphragm constituting part of the phonograph horn I3 travels within the sound track of the phonograph record. A hand switch S is interposed within the circuit for cutting the burglar alarm system into and out of operation.
(Cl. 20G-54) The trip switch 3, as best illustrated in Figs. 2 and 3, comprises a closed box or housing I4, preferably of metal and of comparatively small size. The top of the box includes a control plate I5 having its upper face disposed substantially ilush with the top surface of the box and having its lower surface pivotally connected to a pin I6 extending crosswise of the plate and secured to the two opposite side walls of the box. A coil spring I1 under compression is housed for the major portion of its length in a shell Ila extending up from the bottom of the box I4, but its upper end projects beyond the open upper end of the shell and bears against one end of the pivoted control plate I5. The under side of the plate adjacent its other end is provided with a rubber bumper I8.
Located within the -box is a metal switch plate I9 pivot-ed to a cross-bar 29 extending between the side walls of the switch box. A weak tension spring 2l connected at one end to the switch plate and at its other to the bottom of the box yieldingly holds one end of the switch plate in engagement with a stop pin 22, but permits said end to move downwardly in a clockwise direction (Fig. 3) to engage a flexible contact member 23 extending from an end wall of the switch box.
The end of the switch plate I9 designed to engage the flexible contact member 23 is rolled into cylindrical shape as indicated at 24, so as to depress and thence readily pass under this member. The conductors 4 and 4a of the alarm circuit are connected respectively with the switch plate I9 and the contact member 23, and pass through openings provided in the walls of the box.
The side of the window easement is out away so as to provide an opening for receiving the switch box, with the control plate I5 lying substantially flush with the window trackway, as indicated in Fig. l. The wires 4, 4a connected with the switch will preferably be led through openings drilled in the easement so` as to be concealed from view so far as is reasonably possible.
The operation of the burglar alarm system set forth above is as follows: When the window I is raised by a prowler to a height above the switch 3 suflicient to allow passage of a person through the opening, the control plate I5 under the thrust 5 of compression spring I'I will rotate on the pin I6. This causes the rubber bumper I8 to engage the end of switch plate I9 and kick the latter into engagement with the flexible contact member 23 which yields and allows the rounded end of the switch plate to pass beyond it into the position indicated in dotted lines in Fig. 3 closing the electrical circuit between conductors 4 and 4a. The tension spring 2| is insufficient in strength to restore the switch plate to its original position, but serves to retain the switch plate in contact with the contact member. The stop pin 22 arrests the control plate I5 and restrains it against the action of spring I1. The circuit being closed, current flows from the source C through electric motor 5 to operate the phonograph. The phonograph playing from the record Il gives a warning such asto summon the police or frighten off the prowler.
A time fuse F may be interposed in the line so as to break the circuit after a short period of operation of the phonograph. The hand switch S will preferably be inconspicuously located but accessible for turning on the alarm in the evening and turning it oi in the morning, or otherwise as desired. To recondition the circuit for operation after the trip switch has been actuated, it is only necessary to introduce a hook into the switch box and pull upwardly upon the switch plate and draw it over the contact member 23,
which ilexes to allow the switch plate to assume the position shown in full lines in Fig. 3, then rotate the control plate l5 back into the plane of the top of the switch box where it may be held by closing the window. A new fuse F is thereupon inserted in the circuit and the hand switch S is turned to closed position.
The horn I3 may be placed in any part of the enclosure to be protected, but preferably will face the outside of the building so as to broadcast an alarm when the circuit is closed. Desirably the sound of the phonograph will be amplied as by thermionic tubes in a manner well known in the radio and phonograph speaker art. Or alternatively, several phonographs may be mechanically actuated simultaneously to produce the desired volume of sound.
While in the embodiment of my invention described above only one switch is connected to the electric circuit controlling the phonograph, it is likely that in many instances it will be found desirable to protect several closures, windows or doors for example, with the same alarm. To accomplish this the several switches 3 may be connected in parallel circuits with the phonograph motor 5.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention, and the present embodiment is therefore to be considered as illustrative and not restrictive, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.
1. In an electrical burglar alarm system, a trip switch for completing an electrical circuit for operating an alarm or the like, said switch comprising a switch box adapted to be inserted in the frame of a closure member and having a closure-contacting face, a pivoted switch element and a companion xed member having a flexible contact located within said box and adapted to be connected in the electrical circuit, means for yieldingly maintaining said pivoted switch element separated from said exible Contact, a control plate pivotally supported intermediate its length so as to swing from a position fiush with the closure-contacting face of the box to a position inwardly of the box, when the closure member is moved out of engagement therewith, and a spring normally urging said control plate into striking engagement with the pivoted switch element to depress said member into electrical engagement with the fixed member and latch said iixed member behind the flexible contact element to retain the switch in circuit-closing position independent of the control plate.
2. A trip switch for an electrical burglar alarm system or the like comprising a switch box adapted to be inserted in the frame of a closure member and having a closure-contacting face, a pivoted switch element and a companion fixed member located within said box and having a flexible contact, a spring for normally maintaining said pivoted switch element in spaced relation with respect to said iiexible Contact, a control plate pivotally mounted intermediate its length on said box and adapted to swing from a position iiush with the closure-contacting surface of the box member to a position inwardly of the box, and a spring normally urging said control plate into striking engagement with the pivoted switch element to depress said element into engagement with the xed member and cause said flexible element to latch behind the pivoted switch element and retain the switch closed independent of the position of the control plate.