US607407A - Ments - Google Patents

Description

No. 607,407. Patented .Illly I2, I898. C. COLEMAN.

ALARM SYSTEM.

(Application filed Oct. 18, 1897.)

(N0 Model.)

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NTTED STATES I PATENT FFICE.

CLYDE COLEMAN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGN- MENTS, OF TWO-THIRDS 'IO GEORGE P. JONES, OF SAME PLACE.

ALARM SYSTEM.

SPECIFICATION forming part of Letters Patent No. 607,407, dated July 12, 1898.

Application filed October 18, 1897. Serial No. 655,525. (No model-) To ctZZ whom it may concern:

Be it known that I, CLYDE COLEMAN, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Alarm Systems, of which the following is a full, clear, concise, and exact description, reference being had to the accompanying drawings, forming a part of this specification.

My invention relates to an alarm system, my object being to provide new and improved means whereby localized portions of the electric protective circuit may be varied in character to prevent the tampering with the circuit without sounding an alarm at the alarmstation.

My invention also comprehends a new and improved arrangement of the alarm system whereby any attempt to open the vault door or covering during the intervals that the character of the'circuit remains constant will result in sounding the alarm.

In alarm systems wherein a vault or other inclosure is protected by means of an electrical barrier arranged to operate a signal at the alarm-station when tampered with it has been found necessary to provide means for varying from time to time the character of the circuit Within the vault or within the alarm-station or other localized portions of the circuit, to thus frustrate any attempt to determine the circuit arrangements in order that an equivalent device may be interpolated outside of the protected structure to thereby permit the opening of the vault without sounding an alarm.

In accordance with the present invention a device is provided in one localized portion of the protective circuit, preferably at the alarmstation, for varying the voltage of the circuit, while in another localized portion of the circuit, usually at the protected structure, a de vice is provided which is responsive to the voltage changes and acts to maintain the cur rent constant within prescribed limits notwithstanding the variation of voltage. For producing the variations of voltageI may employ a rheostat, while as a compensating device a second rheostat may be employed which is operated by a magnet responding to the current changes produced by the operation of the first rheostat. Again, a dynamo or generator may be employed the speed or other factor of which may be varied to produce a change of voltage, While as the responsiveand compensating device a motor may be employed the speed of which will antomatically vary with the change of voltage to produce a counter electromotive force that will maintain the current constant. In some of these systems it has been possible, notwithstanding the change of the character of the circuit at intervals, to interpolate an equivalent device during the short interval that the circuit remains constant, then to quickly throw open the vault-door, loop the contacts thereof, and then remove the interpolated device before the character of the circuit changes to permit the system to operate without sounding the alarm, due to the fact that the door-contacts have been looped. The vault-door may be thus opened and the system still remain irresponsive.

It is the object of the present invention to provide means whereby any attempt to loop the door-circuit will permanently change the character of the protective circuit to thus effectively sound the alarm.

In the accompanying drawings, Figure 1 is a view showing the circuits in diagram. Fig. 2 is a view showing the door open. Fig. 3 is a View of a modified form of alarm circuit. Fig. 4 is a View of a second modification. Fig. 5 is a view of a. third modification.

Like letters refer to like parts in the several figures.

At the alarm station is provided a resistance-varying device comprising a vessel a, containing a body of mercury or other conducting liquid ct, connected with one side of the battery I). Immersed in the mercury is a carbon or graphite rod a depending from a pivoted lever a carrying a pin a which rides upon'the periphery of a cam o driven by a clock mechanism a or by other means, as desired. As the cam rotates the rod a is raised and lowered to vary the resistance of the circuit to thereby alter the strength of the current. At the protected structure is provided a similar vessel 0, containing a body of mercury c, in which is immersed a carbon or graphite rod 0 connected with the lever 0 adapted to be raised and lowered by means of the core d of the electromagnet d. The electric protective circuit extends from battery b to contact e, contact e upon the vaultdoor 6 these contacts being in engagement so long as the door is closed. Circuit then extends through the conductors e on the door to contact 6 contact e in engagement therewith, through the electrical barrier 6, protecting the walls of the vault, thence through magnet d, rod 0 mercury c, conductor fto the rod a mercury a, and back to the battery. In the circuit at the alarm-station is the magnet g of a responsive device, the m agnet acting upon the armature-lever g to balance the same against the tension of the spring g and maintain the contact-arm g out of contact with contacts g 9 Any change of the strength of the current through the magnet g counterbalances the armature-lever and closes arm g against one of the contacts, thus closing the circuit of the battery It through bell or sounder h to give the alarm. In the circuit at the protected structure is the magnet k, which acts upon a change in the current to close a short circuit it around the magnet d, as hereinafter described.

The normal operation of the system is as follows: The rotation of the cam of acts to raise and lower the rod a thus varying the voltage and resistance of the circuit to thereby slightly increase or decrease the current flowing over the protective circuit, which immediately acts upon the magnet cl at the alarmstation to vary the resistance through the body of mercury c thereat to compensate for a change in the voltage and resistance produced at the alarm-station. Thus if the rod a at the alarm-station be raised to increase the resistance, and thereby tend to decrease the current flowing, the decreased current causes magnet cl at the protected structure to lower the rod 0 thereat to decrease the resistance of the circuit, and thereby increase the current to its normal value. The variation of the current over the protective circuit is thus very slight, and the magnet d at the protected structure maintains the current constant within prescribed limits. The magnet 9 of the responsive device at the alarmstation is adjusted so that it will not sound the alarm due to the normal slight fluctuations, but will respond to any change of current strength which is more excessive.

In Fig. 3 is illustrated a modification in which a dynamo or generator 0 is provided at the alarm-station driven by a motor 0, the speed of which may be varied at will. At the protected structure is provided a motor 0 supplied with current from generator 0. The responsive device 19 responds to any change of current strength. Any change of speed of the generator produces a corresponding change in the speed of the motor, thereby varying the counter electromotive force of the motor to compensate for the change of voltage of the generator, thus maintaining the current constant. Thus if the speed of the generator increases to increase the voltage thereof the increased voltage to which the motor is subjected causes the same to run at a higher speed, thereby increasing the counter electromotive force thereof to counteract and compensate the increase of voltage of the generator.

In systems of this classwherein the nature or character of the circuit in localized portions is varied from time to time it has been attempted to defeat the system by interpolating in the protective circuit just beyond the protected structure a device which will maintain the same current which flows during any particular interval between the changes of the character of the current. Such an interpolated device lis illustrated in dotted lines. The device is placed in circuit during the short interval that the character of the system remains constant. The vault-door e is then suddenly opened and the contacts thereof are looped by means of conductors Z Z to provide a constant passage for the current through the alarm system notwithstanding the fact that the door is open. The interpolated device I is then thrown out of circuit immediately and before any change in the character of the system is made, and as the character-varying devices then proceed to perform their functions the system fails to give the alarm, since the protective circuit is completed through the loops notwithstanding the fact that the door-contacts have been separated. In order to prevent this looping of the door-contacts in a system of this character during the interval that the character of the system remains constant, I provide a device for permanently changing the character of the circuit by such an attempt to loop the door-contacts, to thus unconditionally cause the sounding of the alarm when the door-contacts are tampered with. This device is illustrated in Fig. 1 as serving to shortcircuit the operating-magnet d at the protected structure; but it may be otherwise arranged to permanently change the character of the circuit.

The magnet is included in the protective circuit and acts upon an armature-lever 70 balanced by a spring 70 and carrying an arm k arranged to engage contacts 70 70", to thereby close the short circuit 70 around the operating-magnet (Z, and thereby permanently cut the same out of circuit and preventing its respouse to the change of voltage produced on the circuit at the alarm-station, thereby permitting a change of the current strength to sound the alarm. contacts for even a short time causes magnet 7a to release its armature to close the shunt 7c. The range of the magnet is such that it does not respond to the normal fluctuations of the current due to the normal changes of the voltage.

A switch m, Fig. 1, is preferably provided The separation of the door whereby the door-circuit may be shunted when it is desired to open the vault. The switch is preferably operated by a combination-lock or in any other manner, whereby it may be operated only by authorized parties.

In Fig. 4 the device for periodically chang-,

. of the door-contacts the magnet releases its armature and closes ashort circuit is around the resistance 70 and around the magnet is. In Fig. 5 the magnet 70 norm ally holds a switch k in position to close the protective circuit. Upon the separation of the door-contacts the magnet is deenergized to permanently open the protective circuit.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. The combination with an electric protective circuit extending between a protected structure and the alarm-station, of a voltagechanger for varying the Voltage of the current flowing thereover and a device responsive to said voltage variations acting to maintain the current constant within prescribed limits, substantially as described.

2. The combination with an electric protective circuit, of a voltage-changer situated therein at the alarm-station, a device responsive to said voltage-changer situated at the protected structure and acting to maintain the current constant within prescribed limits, substantially as described. I

3. The combination with a protective circuit protecting a vault or other inclosure and extending through separable door-contacts,of means for varying the nature of the circuit within the vault at intervals, and a device responsive to a momentary vseparation of the door-contacts to permanently change the nature of the circuit, substantially as described.

In witness whereof I have hereunto subscribed my name in the presence of two witnesses.

CLYDE COLEMAN.

Witnesses: W. CLYDE J ONES, M. R. RocHFoRD.

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