Self-contained Unauthorized Entry Alarm

Abstract

The entry alarm of this invention is especially useful in apartments where ease of installation and removal are highly desirable. Specifically, the invention comprises a battery operated alarm system which is completely contained within a inverted U-shaped assembly designed to fit quite simply over the top of a door and to be held in place with ordinary double-sided tape. The system includes a sensor which sets off a battery operated alarm unless a code-operated device on the outside of the door is correctly manipulated prior to the opening of the door.

Description

BACKGROUND OF THE INVENTION

The apartment dweller has for years had a problem with respect to burglar protection. Most apartments are not equiped with alarm systems to warn of the unauthorized entry or attempted entry by a burglar or other unwanted individual, and the doors are often not adequate to prevent a forced entry even though locked. In addition, it is accepted practice for strangers to come and go substantially unnoticed in multiple dwelling apartments.

Tenants in most cases are prohibited from making fixed improvements to their apartments unless they agree to leave the improvements when they vacate or to bear the expense of returning the premises to their original condition. In our mobile society apartment dwellers often change their residences after only brief stays, and for such individuals neither of the just mentioned alternatives are especially attractive as alarm systems are expensive and normally require that a certain amount of damage be done during installation. The result is quite often that the extent of installed unauthorized entry protection is an additional lock.

It is therefore an object of this invention to provide a simple unauthorized entry alarm system for apartments which can be installed easily without any need to cause any damage to the apartment either during installation or removal.

A further objective of this invention is to provide an alarm system for mounting on an apartment door having a portion of the device on the outside of the door which contains a code operated means which would, when properly manipulated, render the alarm inoperative.

Further objectives and advantages of this invention will be apparent from the hereinafter descriptions and drawings.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of one form of the invention as it would appear in the installed condition over the top of an ordinary door.

FIG. 2 is a schematic of one circuit which is useful in the operation of this invention.

DESCRIPTION OF PREFERRED EMBODIMENT

This device is designed for ease of installation, and the manner in which this objective is accomplished is best described in conjunction with the illustration thereof in FIG. 1. The alarm system is entirely contained with three separate members. Housings 1 and 2 and connected by an L-shaped bracket 3. The housings 1, 2 are hollow members containing the operative components of the alarm circuit and may be constructed of any of a variety of materials, but housing 1 preferably should be of a durable substance which is highly resistent to being broken into by someone attempting to open the door without sounding the alarm. Steel has very desirable characteristics for this purpose.

Bracket 3 may be constructed of a single solid piece, but for reasons which will be made clear later when the circuit of FIG. 2 is discussed, is preferably made of two separate laminations 11 and 12. As this bracket is also exposed to anyone who might try to gain entry to the apartment without sounding the alarm, it should also be constructed of a durable material such as steel. Bracket 3 is solidly connected to housing 1 but is connected to housing 2 by screws 4 which are mounted to housing 2 through elongated slots 5 in the bracket. These slots permit the spacing between the housings to be adjusted to accommodate fitting snugly over doors of varying thicknesses. In order to permit the door to be closed, it is necessary to have housing 1 mounted on bracket 3 a short distance down from the top of the door so that the housing will not strike the door frame.

The installation of this system is accomplished by loosening screws 4 and placing the device over the top of the door. The housings are then pressed togethed until they are snugly against each side of the door. Screws 4 are then tightened. In order to prevent the device from slipping along the door as it is openned and closed small nails or tacks may be driven into the top of the door through holes 9. These nails would do very little harm, if any, and they would be out of sight. An alternate means for holding the device in place is two-sided tape. A short strip could be placed on the side of each of the housings adjacent the door.

The location of the device along the door is not critical, but it will be more sensitive to slight openings of the door if it is placed near the edge of the door away from the hinges.

With the device in place on the door, it can be activated by turning the key operated switch 16 to the closed position and adjusting bolt 6 so that the alarm is silent when the door is closed but is activated by any attempt to open the door. This adjustment will vary from one door to another depending on how free the individual door is to wobble in the closed position.

The manner in which this alarm system operates and the functions of the various switches (S1, S2, S3, S4, S5, and S6 are switches and key 16, button 15, and leaf spring 7 all operate switches) are best understood from a study of FIG. 2. In this figure a dotted line is used to enclose those components which are located in housing 1.

In FIG. 2 boxes 20 and 22 represent buzzers or any other device which can be operated off a battery and which preferably make a great deal of noise. Two buzzers are in the circuit to provide an alarm both inside the apartment to alert the tenant and outside the door to be more effective in alerting the neighbors. These buzzers are connected in parallel with one another and this parallel combination is connected in a series circuit with battery 30, key operated switch 16 and SCR 26.

Switch 16 is for the purpose of permitting the tenant to turn the system on or off as he desires with some assurance that it will stay that way until he uses his key to alter it. For the purposes of the following it can be assumed that switch is in the closed condition unless specifically stated otherwise. With this being the case, it is apparent that the buzzers will sound when SCR 26 is switched on and will otherwise be silent.

SCR 26 will conduct when current is permitted to flow through R2 thereby putting a positive voltage on the SCR's gate terminal which is connected to the junction point between resistors R1 and R2. These resistors are connected in a series circuit with momentary switch 15, switch 8 and a parallel arrangement of switches S1, S2, S3, S4, S5 and S6. This series circuit is connected directly across battery 30, and when all the switches complete the circuit through the battery, SCR 26 will be turned on and the alarm will sound.

Momentary switch has a function which is discussed below, but is normally in the closed position. Switch 8 is operatively connected to leaf spring 7 and bolt 6 illustrated in FIG. 1 and when the door is closed and bolt 6 is properly adjusted, switch 8 is open. When the door is openned, the bolt is moved away from the door frame, and spring 7 is permitted to move toward the door frame and in the process close switch 8. If when this happens any of S1, S2, S3, S4, S5 or S6 are in a position connecting line 40 to line 42, current will flow through R2, and the alarm will be operated.

It should be noted that switches S1 to S6 are connected in what can be referred to as an OR arrangement, i.e., if any one switch is in the improper position the circuit is made and the alarm sounds. It is therefore apparent that when the system is activated, one can not open the door from the outside without the alarm sounding unless he knows the combination of positions for the six switches which will not complete the circuit. In FIG. 2 the switches are wired so that S1, S2, S4 and S6 must be in the normally closed position (all the switches having only two positions) to open the door quietly. With six two position switches there 64 different combinations, but this number can be increased by adding more switches or by utilizing a different coded device such as a rotary combination lock system.

In view of the fact that the occupant of the dwelling will have many occasions when he wants to open the door without any need for the alarm to sound, momentary button 15 has been provided. This button functions to disable the alarm for only so long as it is depressed. In the embodiment illustrated in FIG. 1 both this momentary switch and the key operated switch are shown, for purposes of convenience, on the side of housing 2 toward the door knob. They need not be in the illustrated position, and preferably are elsewhere so that they can not be reached easily from the outside through a partially openned door.

Lines 40, 42, 44 and 46 must run from housing 1 to housing 2, and they therefore must be protected from an intruder who might try to disable the alarm by cutting these lines. It is for this purpose that the preferred construction of bracket 3 is of the laminar form described above. Lines 40, 42, 44 and 46 may then be of ribbon conductor which can easily fit between the laminations.

Having set forth the invention in what is considered to be the best embodiment thereof, it will be apparent that changes may be made in the system as set forth above without departing from the spirit of the invention or exceeding the scope thereof as defined in the following claims.

Claims

We claim:

1. In a self-contained electrically operated alarm system for signaling the unauthorized opening of a door which system includes a sensor means for signaling the door-open condition and a code operated means on the outside of the door which when properly manipulated permits the opening of the door without said sensor means actuating the alarm wherein the improvement comprises first housing means, second housing means, interconnecting means between said first and second housing means which can be placed around one edge of the door with said first and second housing means on opposite sides of the door, said interconnecting means of a thickness less than that which would prevent an ordinary door from closing when said interconnecting means is in place, said first housing means containing the electrical power supply, alarm means and sensor means, said second housing means containing said code operated means.

2. An alarm system according to claim 1 wherein said interconnecting means is laminated over at least a portion thereof.

3. An alarm in accordance with claim 1 wherein said interconnecting means is made of steel.

4. An alarm system according to claim 1 wherein said code-operated means operates an electrical switch in circuit with said circuit elements contained in said first housing means, and wherein electrical connection means between said code-operated means and said circuit elements is coextensive with at least a portion of said interconnecting means on the outside of the door and that portion around one edge of the door.

5. An alarm system according to claim 2 wherein there is included electrical connection means extending between said first and second housing means, said electrical connection means placed between laminations of said interconnecting means.

6. An alarm system according to claim 5 wherein at least the lamination of said interconnecting means exposed to the outside is steel.