US3890608A

US3890608A - Door monitoring and controlling device for a security system

Info

Publication number: US3890608A
Authority: US
Inventors: Francis C Peterson
Original assignee: C Hager and Sons Hinge Manufacturing Co
Current assignee: C Hager and Sons Hinge Manufacturing Co
Priority date: 1972-10-11
Filing date: 1972-10-11
Publication date: 1975-06-17
Anticipated expiration: 1992-06-17

Abstract

A security system for monitoring and controlling the operation of doors from a remote location includes door locks, each having a retractable latch bolt which projects into a strike and keeps the door from opening, auxiliary latching means which block the latch bolt to prevent it from being retracted by a thin object passed along the strike, operating means for manually retracting the latch bolt, and a solenoid operated locking mechanism for locking the operating means. The lock is further provided with a switch for sensing the position of the auxiliary latching mechanism and another switch for sensing the position of the locking mechanism. The two switches are connected through a contact hinge to an alarm at the remote location, while the solenoid is connected through the contact hinge to an operating switch at the remote location. The alarm is actuated not only by the sensing means but also by the hinge as it opens. The alarm can be cancelled only by closing a key-operated switch at the door so security personnel must investigate the cause for an alarm.

Description

United States Patent 1 1 Peterson 1 DOOR MONITORING AND CONTROLLING DEVICE FOR A SECURITY SYSTEM [75] inventor: Francis C. Peterson, Affton, Mo.

[73] Assignee: C. Hager & Sons Hinge Manufacturing Company, St. Louis, Mo.

22 Filed: Oct.ll, 1972 21 Appl. No.: 296.561

[52] US. Cl. 340/274; ZOO/61.64, 200/617; 315/84; 292/D1G. 25; 70/D1G. 49; 339/4 [51] Int. Cl. G08b 13/08 {58] Field of Search 340/274. 276:2(10/6162, ZOO/61.64, 61.67, 61.68, 61.7; 315/84;

DIG. 24, DIG. 25

[56] References Cited UNITED STATES PATENTS 3,070,784 12/1962 Strand 340/274 3,148,525 9/1964 Dorant 70/280 X 3,157,042 11/1964 W012 I 70/279 3,160,720 12/1964 Faulkner 200/44 3,353,383 11/1967 Fish I I 340/274 3,383,674 5/1968 Soltan et a1 340/274 X 3,432,631 3/1969 Deutscher et al..... 200/6167 3,570,285 3/1971 3,751,086 8/1973 Geringer 292/144 X 1 June 17, 1975 Schlage 292/201 Van Wyck 292/144 [57] ABSTRACT A security system for monitoring and controlling the Operation of doors from a remote location includes door locks, each having a retractable latch bolt which projects into a strike and keeps the door from opening, auxiliary latching means which block the latch bolt to prevent it from being retracted by a thin object passed along the strike, operating means for manually retracting the latch bolt, and a solenoid operated locking mechanism for locking the operating means The lock is further provided with a switch for sensing the position of the auxiliary latching mechanism and another switch for sensing the position of the locking mechanism. The two switches are connected through a contact hinge to an alarm at the remote location, while the solenoid is connected through the contact hinge to an operating switch at the remote location. The alarm is actuated not only by the sensing means but also by the hinge as it opens. The alarm can be cancelled only by closing a key-operated switch at the door so security personnel must investigate the cause for an alarm.

14 Claims, 7 Drawing Figures PATENTEDJUH 11 ms 513950 3 SHEET DOOR MONITORING AND CONTROLLING DEVICE FOR A SECURITY SYSTEM BACKGROUND OF THE INVENTION This invention relates in general to security systems and more particularly to a security system wherein doors are controlled from and monitored at a remote location.

Many buildings are too large for security personnel to effectively patrol and as a result intruders often gain access to these buildings and wander throughout them without being detected. Indeed, forceable entries into buildings and intrusions into restricted areas thereof represent a major problem for building managers and security personnel, as well as law enforcement agencies.

Heretofore, attempts have been made to remotely control door locks from a central location, but most of these attempts have involved incorporating electrically operated release mechanisms into the lock strikes on door frames. In arrangements of this nature, the strike jamb of the door frame must be specially prepared to accommodate the release mechanism; and the special preparation is usually quite expensive. Moreover, these devices release the door once they are energized and as a result the door will swing open in strong drafts. This is particularly hazardous in the event of a tire since the door cannot be unlocked to permit trapped people to escape and still be secured against opening in the presence of drafts created by the fire. Hence, strike centered release mechanisms contribute to the spread of fires. Also, strike centered systems are easily violated.

Surveillance systems have also been developed for monitoring locks, but these systems are also for the most part strike centered. Hence, while they may provide some indication of the condition of the electric release mechanism in the strike jamb, they provide no indication as to the position of the door. Thus, the release mechanism could be closed while the door is slightly ajar and the monitoring system would not recognize the break in security.

Aside from the foregoing, the alarms of some monitoring systems can be reset at the central location. This enables a lazy guard to merely cancel an alarm without investigating the cause for the alarm.

Finally, it should be noted that the best locks of current construction utilize an auxiliary latch in lieu of a dead bolt to prevent unauthorized opening of the lock with a plastic credit card or some other thin device capable of being inserted between the strike and the door. The auxiliary latch engages the strike and depresses as the door closes and when depressed allows a locking lever to fall behind the latch bolt. Thus, the latch bolt cannot be forced back into the lock with a plastic credit card. The usual practice for violating a lock of this nature is to place a piece of adhesive tape over the auxiliary latch and latch bolt when the door is open and then come back at some later time when the door is supposed to be locked. Of course, the door will not be locked at that time by reason of the adhesive tape, and thus access is gained to the area which would otherwise be protected.

SUMMARY OF THE INVENTION One of the principal objects of the present invention is to provide a security system having electrically operated locks which can be controlled from a remote location. Another object is to provide a security system which monitors the positions of doors as well as the condition of locks associated with the doors. A further object is to provide a security system which monitors both the electrical locking mechanism and the auxiliary latch of the lock. An additional object is to provide a security system having an alarm which cannot be cancelled without going to the door from which the alarm originated. Still another object is to provide a lock having auxiliary latching means to prevent unauthorized retraction of the latch bolt and further having sensing means for sensing the position of the auxiliary latching means and the locking mechanism. These and other objects and advantages will become apparent hereinafter.

The present invention is embodied in a security system having a lock provided with sensing means which set off an alarm when a security violation occurs at the door in which the lock is installed. The invention is also embodied in a security system wherein an alarm can only be cancelled at the location of the security violation which caused the alarmto be energized. The invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed.

DESCRIPTION OF THE DRAWINGS In the accompanying drawings which form part of the specification and wherein like numerals and letters refer to like parts wherever they occur:

FIG. 1 is a perspective view of a door provided with a lock and contact hinge forming part of the security system of the present invention;

FIG. 2 is a perspective view of the contact hinge;

FIG. 3 is a sectional view of the lock showing it in its locked condition;

FIG. 4 is a sectional view similar to FIG. 3 but showing the lock in its unlocked and open condition;

FIG. 5 is a schematic diagram of the electric circuit forming part of the present invention;

FIG. 6 is a schematic diagram of a modified circuit; and

FIG. 7 is a sectional view of a modified lock in its locked condition.

DETAILED DESCRIPTION Referring now to the drawings (FIG. 1), D designates a door which is hung on and swung away from a door frame 2 having a strike jamb 4 and a hinge jamb 6. The door D is actually hung on

hinges

8 and 10 which are attached to the hinge jamb 6. The hinges 8 are conventional full mortise hinges, while the hinge 10 which is also a full mortise hinge, is a so-called contact hinge which completes several electrical circuits when closed. The door D is provided with a lock L, while the strike jamb 4 is fitted with a keeper or strike 12 which the lock L engages and thereby prevents opening of the door D.

The contact hinge 10 (FIG. 2) is disclosed in U.S. Pat. No. 3,659,063 and for purposes of this discussion it is sufficient to note that the hinge 10, like the conventional hinges 8, has leaves 14 and 16, but that the leaf 14 has four

contacts

18a, 18b, 18c, and 18d, while the other leaf 16 has four spring loaded

contactors

20a, 20b, 20c, and 20d which align with and engage the

contacts

18a, 18b, 18c, and 18d, respectively, when the hinge 10 is closed. However, when the hinge l0 opens the contacts 18 separate from their respective contactors 20. The contacts l8 and contactors 20 are set in dielectric bushings 22 which insulate them from the

hinge leaves

14 and 16 and from one another. Thus, the hinge when closed can complete four different electrical circuits.

The lock L is a standard mortise lock which is modi fled to enable it to be locked or unlocked electrically from a remote location as well as manually at the door D. It is also modified to enable it to be monitored at the remote location. The basic lock illustrated in the draw ings (FIGS. 3, 4, and 7) is manufactured by The Corbin Lock Co, but it should be recognized that locks of other manufacturers may be utilized in the present inventionv The lock I. (FIG. 3) includes a housing 30 to which a face plate 32 is attached. Both the housing 30 and face place 32 are recessed into the door D, but the face plate 32 is flush with and exposed at the narrow side face of the door D.

Mounted in the housing 30 is a latch bolt 34 which moves between a retracted position, wherein it is contained entirely within the housing 30 (FIG. 4), and an extended position, wherein a portion of it projects outwardly beyond the face plate 32 (FIG. 3). When the door D is closed and the latch bolt 34 is in its extended position, the latch bolt 34 will project into an opening in the strike I2 and prevent the door D from being opened. The latch bolt 34 is urged to its extended position by a coil-type compression spring 36.

In addition to the latch bolt 34 the lock L is further provided with an auxiliary latch 38 which pivots on the face plate 32 and is normally urged outwardly beyond the face plate 32 by a spring loaded auxiliary latch lever 40 (see dotted lines in FIG. 4). The latch lever 40 pivots on the housing 30 and is urged against the auxiliary latch by a spring 42. The auxiliary latch lever 40 in turn operates a locking element or lever 44 which pivots on the housing 30 about a pivot point 46 located adjacent to the rear wall of the housing 30, and as it pivots it moves between a blocking position, wherein it is disposed behind the latch bolt 34 (FIG. 3), and a release position, wherein it is disposed above the latch bolt 34 and does not prevent the latch bolt 34 from moving to its retracted position (FIG. 4). The locking lever 44 is urged to its blocking position by a locking lever spring 48. The auxiliary latch 38, the auxiliary lever 40, the latch lever spring 42, the locking lever 44 and the lock ing lever spring 48 constitute auxiliary latching means and are all configured such that the locking lever 44 will be retained in its release position (FIG. 4) when the auxiliary latch 38 is projected outwardly beyond the face plate 32, but will be free to fall into its blocking position when the auxiliary latch 38 is depressed (FIG. 3). Thus, when the door D is open, the auxiliary latch 38 is projected beyond the face plate 32 and the locking lever 44 does not obstruct movement of the latch bolt 34 to its retracted position (see dotted lines in FIG. 4). However, as the door D is closed the latch bolt 34 first engages the strike 12 and is cammed toward its retracted position, and shortly thereafter the auxiliary latch 38 also engages the strike I2 and is moved inwardly into the housing 12. When the door moves into its fully closed position the spring 36 drives the latch bolt 34 outwardly and into the opening in the strike 12. The auxiliary latch 38, however, remains against the strike 12 and depressed. As the latch bolt 34 moves toward the strike 12 and into its extended position, the

locking lever 44' falls downwardly to its blocking position and blocks retraction ofthe latch bolt 34 (FIG. 3). Thus, when the door D is closed, a credit card or other thin object inserted between the lock face plate 32 and the strike 12 cannot force the latch bolt 34 to its retracted position. The locking lever 44 will prevent this. From the foregoing it is apparent that the auxiliary latch 38 serves as the control element for the auxiliary latching means comprised of the latch 38, the levers and 44, and the

springs

42 and 48.

In addition, the lock L has a cylinder 50 which when operated pivots a cylinder lever 52 and the cylinder lever 52 in turn lifts the locking lever 44 to its release position and further engages the latch bolt 34 and moves it to its retracted position. Thus, the lock L can be opened by inserting a key into the cylinder and turning it.

The lock L has knobs 54 (FIG. I) which are presented beyond the front and back faces of the door and these knobs 54 are mounted on a spindle 56 (FIG. 3) which extends through the door D as well as through the lock housing 30. Indeed, the spindle 56 extends through a spindle hub 58 within the housing 30, and this hub when rotated by turning one of the knobs 54 operates a hub lever 60 which engages the cylinder lever 52 and causes it to pivot as if it had been pivoted by the cylinder 50. Thus, when one of the knobs 54 is turned the locking lever 44 will likewise be lifted and the latch bolt 34 retractedv The spindle hub 58 has a notch 62 which opens toward the face plate 32 and normally aligns with a sliding dog 64 which is confined by the housing 30 and face plate 32 and slides into and out of the notch 62. Of course when the dog 64 is in the notch 62 (FIG. 3), the spindle hub 58 cannot be turned and the latch bolt 34 cannot be retracted by turning the knobs 54. However, when the dog 64 is located beyond the notch 62, (FIG. 4) the spindle hub 58 is free to rotate and the latch bolt 34 can be retracted by turning the knobs 54.

The sliding dog 64 further has a laterally projecting boss 66 which is received in the bifurcated end of an operating lever 68 having a pivot pin 70 projected from it intermediate its ends. The pivot pin 70 extends into and is confined by the housing 30, enabling the operating lever 68 to pivot relative to the housing 30 and thereby move the dog 64 into and out of the notch 62 in the hub 58. The opposite end of the operating lever 68 is connected pivotally to a draw member 72 which extends rearwardly through the back wall of the housing 30. The outer end of the draw member 72 is connected to the armature of a solenoid 74 which is mounted on the housing by means of a bracket 76. The armature of the solenoid 74 is urged outwardly toward the housing 30 by a spring 78, and when the armature is so positioned, the draw member 72 positions the operating lever 68 such that it holds the sliding dog 64 in the notch 62 of the spindle hub 58. Thus, when the solenoid 74 is not energized (FIG. 3), the spindle hub 58 cannot be rotated and the latch bolt 34 cannot be retracted by turning the knobs 54. However, when the solenoid '74 is energized (FIG. 4) the draw member 72 will move rearwardly and cause the operating lever 68 to pivot about its pin This will move the dog 64 out of the notch 62 in the sp'irldle hub 58 so that the latch bolt 34 can be retracted by turning one of the knobs 54. The sliding dog 64, the operating lever 68, the draw member 72, and the solenoid 74 constitute a locking mechanism which moves between locked and unlocked positions.

The pivot point 46 of the locking lever 44 is adjacent to the back wall of the housing 30, and near that pivot point the locking lever 44, in contrast to conventional locking levers, is provided with a switch actuating tab 80 which projects upwardly along the back wall. Directly opposite from the end of the actuating tab 80 the back wall of the housing 30 is fitted with a microswitch 82 which is operated by the switch actuating tab 80. When the locking lever 44 is in its blocking position. that is when it is behind the latching bolt 34, the switch 82 is closed (FIG. 3). However, when the locking lever 44 is raised to its release position, in which case the latch bolt 34 is free to retract, the actuating tab 80 holds the switch 82 in its open position (FIG. 4).

The end wall of the solenoid 74 is fitted with another microswitch 84 which is operated by the armature of the solenoid 74. When the armature is extended, in which case the locking mechanism is in its locked condition so that the knobs 54 cannot be rotated (FIG. 3), the switch 84 is closed. However, when the solenoid 74 is energized and its armature is retracted, in which case the locking mechanism is in its unlocked condition so that the knobs 54 are free to rotate and thereby retract the latch bolt 34 (FIG. 4), the microswitch 84 opens.

The two

switches

84 and 82 are connected in series (FIG. 5) and the series combination is connected by

conductors

86 and 88 to the contacts 181: and 186 on the leaf 14 of the contact hinge 10. The

conductors

86 and 88 are contained wholly within the interior of the door D and therefore cannot be tampered with when the door D is closed. The corresponding contactors 20b and 20c on the other leaf 16 of the hinge are connected with a central control unit 90 in a remote security room by means of conductors 92 and 94.

One terminal of the solenoid 74 is also connected to the conductor 88 leading from the hinge contact 180, while the other terminal is connected to a conductor 96 which passes through the interior of the door D and is connected to the contact 18a on the leaf 14 of the contact hinge 10. The corresponding contactor a on the other hinge leaf 16 is connected by means ofa conductor 98 to the central control unit 90.

The central control unit 90 includes a switch which when closed causes a current to flow through the

conductors

98 and 96 to the coil of solenoid 74, and thence through the conductors 86 and 94 to the control unit 90. This current actuates the solenoid 74 and causes the dog 64 to release the spindle hub 58 so that the knobs 54 can turn and retract the latch bolt 34 (FIG. 4). The current passes through the hinge 10 at the

contacts

18a and 18c and

contactors

20a and 20c.

In addition, the control unit 90 contains an alarm, which may be a light, and this alarm is energized when the circuit containing the two

switches

82 and 84 is broken. This circuit includes the

conductors

92, 86, 88 and 94 as well as the

hinge contacts

18b and 18c and the corresponding contactors 20b and 20c. Once the alarm is energized by breaking the foregoing circuit, it will remain energized even if the foregoing circuit is again completed. The alarm is reset by closing a normally open reset switch 100 located in the hinge jamb 6, and connected between the conductor 98 and another conductor 102 leading back to the control unit 90. The reset switch 100 is key operated so that only security personnel with the proper key can cancel the alarm.

OPERATION When it is desired to maintain the lock L in an unlocked condition (FIG. 4), such as during working hours, the solenoid 74 is energized from the control unit 90. This causes the dog 64 to move out of the notch 62 in the spindle hub 58 and to remain out of that notch. In other words, energizing the solenoid 74 moves the locking mechanism to its unlocked condition. Consequently, the knobs 54 are free to turn and anyone desiring to pass through the door opening need only turn one of the door knobs 54 and then open the door D. Of course, when the door knob 54 is turned the latch bolt 34 is retracted and this frees the door D to swing outwardly on its

hinges

8 and 10. It is significant to note, however, that even when the locking mechanism is in its unlocked condition, the latch bolt 34 still projects into the strike 12. Hence, the door D cannot be blown open by fire-induced drafts as is the case with strike centered release arrangements.

After Working hours, the door D is secured by the lock L and is further monitored at the central control unit 90. In particular, the solenoid 74 is de-energized, and the solenoid spring 78, acting through the draw member 72 and operating lever 68, causes the sliding dog 64 to enter the notch 62 in the spindle hub 58 (FIG. 3). This prevents the hub 58 from rotating which in turn prevents the latch bolt 34 from being retracted. Anyone attempting to retract the latch bolt by slipping a thick piece of plastic or other material between the face plate 32 of the lock L and the strike l2 will be foiled, since the locking lever 44 is positioned behind the latch bolt 34, preventing its retraction.

If at the close of working hours the door D is left open, the electrical circuit through the door D will be broken at the

contacts

18b, and 18c and the contactors 20b and 20:." of the contact hinge l0, and the control unit 90 will signal an alarm.

On the other hand, should a piece of adhesive tape be placed over the latch bolt 34 and the auxiliary latch 38 to hold them both in their retracted positions after the door D is closed, or if the latch bolt 34 and auxiliary latch 38 are held in their retracted position in some other unauthorized manner, the locking lever 44 will remain in its release position. In that position its actuating tab holds the microswitch 82 open so that the electrical circuit through the door D is broken at the microswitch 82. Again, the alarm sounds.

If only the auxiliary latch 38 is depressed in some unauthorized manner, such as by a piece of adhesive tape, then the locking lever 44 will drop to its blocking position and prevent movement of the latch bolt 34 to its fully retracted position. Consequently, the door D cannot be fully closed and the alarm circuit will be broken at the

contacts

18b and 18c and the contactors 20b and 20c of the contact hinge 10.

If the solenoid 74, the draw member 72, the operating lever 68, sliding dog 64 or spindle hub 56 jambs or otherwise fails to move in such a manner that the dog 64 enters the notch 62 in the spindle hub 58, then the solenoid armature will remain retracted and hold the microswitch 84 in its open position. Thus, the alarm circuit will be broken at the switch 84 and the alarm in the control unit will be energized. In other words, if the locking mechanism fails to lock the spindle hub 58 against rotation, then the switch 84 will be open and the alarm will be energized.

In summary, an alarm will sound at the remote control unit 90 if any of the following breaks in building security occur at the door D:

l. the door fails to close completely;

2. the latch bolt 34 is in some unauthorized manner held in its retracted position;

3. the auxiliary latch 38 is in some unauthorized manner held depressed; or

4. the locking mechanism which locks the door knobs 54 against rotation jambs or otherwise malfunctions.

Once the alarm is energized at the control unit 90, it cannot be cancelled at the control unit 90. On the contrary, the reset switch 100 on the hinge jamb 6 must be closed, and this requires the presence of security personnel at the door D. Thus, the security personnel must investigate the cause for the alarm.

in most buildings a plurality of doors D are controlled and monitored from tl control unit D, and these doors are usually located at key locations such as at the entrances to stairwells or at the entrances to restricted areas,

MODIFICATIONS In lieu of being connected in series the

switches

82 and 84 may be connected in parallel across the conductors 86 and 88 (FIG. 6). In that case the switch 82 should be open when the locking lever 44 is in its blocking position and should close when the locking lever 44 moves to its release position. The switch 84, on the other hand should close when the locking mechanism is open and the knobs 54 are thereby free for rotation. However, when the locking mechanism is in its locked position, and the knob 54 cannot rotate, the switch 84 is open. In addition, the hinge is provided with a switch 110 which is held open while the hinge 10 is closed, but closes when the hinge 10 opens. The switch 110 is connected across the conductors 94 and 92. Such a hinge is described in the United States patent application of Francis C. Peterson, Ser. No. l75,594, filed Aug. 27, l97l. Finally, the remote control unit 90 is constructed such that the alarm thereof is energized when the conductors 92 and 94 are shorted. This occurs when the door D opens, and the switch 110 closes, or when the door D is closed and either one of the

switches

82 or 84 is closed.

By joining the dog 64, the operating lever 68, and the draw member 72 into a unitary structure or operating member 120 (FIG. 7) which slides to and fro with the armature of the solenoid 72, the knobs 54 are locked against rotation when the solenoid 74 is energized and are free to rotate when the solenoid 74 is de-energized. In such a case the microswitch 84 should be such that it closes when the solenoid 74 is energized and the knobs 54 are locked against rotation and opens when the locking mechanism moves ot its release position, provided the switches 81 and 84 are wired in series.

This invention is intended to cover all changes and modifications of the example of the disclosure which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. In a security system for monitoring a door in a door frame, and including a strike on the door frame and an alarm, an improved lock comprising: a retractable latch bolt movable between extended and retracted positions and normally urged to the extended position, the latch bolt when in its extended position being projected beyond the door for engagement with the strike to secure the door in a closed position, the latch bolt when in its retracted position being located beyond the strike so that the door is released from the strike and can be opened, retracting means for moving the latch bolt to its retracted position; a locking element movable between blocking and release positions, the locking element when in its blocking position preventing the latch bolt from moving to the retracted position, the locking element when in its release position permitting the latch bolt to move to its retracted position, the locking element being held in its release position by the latch bolt when the latch bolt is in its retracted position; an auxiliary latch projecting beyond the door when the door is open for engagement with the strike as the door is closed and being depressed by the strike when the door is closed, the auxiliary latch being connected with the locking element for holding the locking element in its release position when the door is open and the auxiliary latch is projected beyond the door, the auxiliary latch when depressed permitting the locking element to move to its blocking position, whereby the locking element will assume its blocking position only when the latch bolt is in its extended position and the auxiliary latch is depressed, and a switch operated directly by the locking element such that the switch condition changes with each movement of the locking element between its release and blocking positions, the switch being electrically connected with the alarm, whereby the switch monitors the position of the locking element.

2. The structure according to claim 1 wherein the locking element pivots between its release and blocking positions about an axis fixed in position with respect to the door.

3. The structure according to claim 1 wherein the retracting means is manually operated and includes at least one handle which is grasped.

4. A security system according to claim 1 wherein the door is attached to the door frame by a hinge and the alarm is connected to the hinge and is energized when the door opens.

5. A security system according to claim 4 wherein the switch is connected to the alarm through the hinge.

6. A security system according to claim 4 wherein the door is attached to the door frame by a hinge having two leaves, contacts on one leaf, and contactors on the other leaf, the hinge being closed when the door is closed, and the contacts being engaged with the contactors when the hinge is closed and being separated from the contactors when the hinge is opened; and wherein the switch is connected to the alarm through the contacts and contactors.

7. A security system according to claim 6 wherein the contacts and contactors are in an electrical circuit with the alarm; and wherein the alarm is energized when the circuit is interrupted at the contacts and contactors, whereby when the door is opened the alarm will be energized.

8. A security system for monitoring a door hinged to a door frame, said security system comprising a strike on the door frame; a lock on the door, the lock including a retractable latch belt which is capable of projecting from the door into the strike to secure the door in a closed position, manually operable retracting means for retracting the latch bolt, means movable to a locked condition for dogging the retracting means so the retracting means cannot be manually operated to open the door, and auxiliary latching means movable between blocking and release positions for preventing retraction of the latch bolt when in the blocking position and for permitting retraction of the latch bolt when in the release position, the auxiliary latching means being responsive to the position of the door and being in the release position when the door is open; an alarm; a first switch connected to the alarm and monitoring the locking means such that the first switch changes condition as the locking means moves into and out of its locked condition and will actuate the alarm only when the locking means is out of its locked condition; a second switch connected to the alarm and operable by the auxiliary latching means such that the second switch changes condition with each movement of the auxiliary latching means between its release and blocking positions and will actuate the alarm only when the auxiliary latching means is in its release position; and means connected with the alarm and responsive to the door position for operating the alarm when the door is away from its closed position, said last named means being at the hinges for the door.

9. A security system according to claim 8 wherein the alarm is located remote from the door; wherein the alarm is connected to a reset switch located at the door; and wherein the alarm, once energized, cannot be cancelled without operating the reset switch, whereby security personnel must investigate the cause of the alarm.

10. A security system according to claim 8 wherein the locking means includes a dogging element which moves into and out of engagement with the manually operable means, and a solenoid connected with the dogging element for moving it.

11. In a security system for monitoring a door in a door frame, and including a strike on the door frame and an alarm, an improved lock comprising: a retractable latch bolt movable between extended and retracted positions and normally urged to the extended position, the latch bolt when in its extended position being projected beyond the door for engagement with the strike to secure the door in a closed position, the latch bolt when in its retracted position being located beyond the strike so that the door is released from the strike and can be opened; retracting means for moving the latch bolt to its retracted position, the retracting means being manually operated and including at least one handle which is grasped; a dogging element movable independently of the retracting means between engaged and disengaged positions and when in the engaged position being engaged with the retracting means such that it prevents operation of the retracting means, whereby the latch bolt cannot be retracted with the retracting means; a solenoid connected with the dogging element for moving the dogging element from one of its positions to the other of its positions; a locking element movable between blocking and release positions, the locking element when in its blocking position preventing the latch bolt from moving to the retracted position, the locking element when in its release position permitting the latch bolt to move to its retracted position, the locking element being held in its release position by the latch bolt when the latch bolt is in its retracted position; an auxiliary latch projecting beyond the door when the door is open for engagement with the strike as the door is closed and being depressed by the strike when the door is closed, the auxiliary latch being connected with the locking element for holding the locking element in its release position when the door is open and the auxiliary latch is projected beyond the door, the auxiliary latch when depressed permitting the locking element to move to its blocking position; a first switch operated by the locking element such that the switch condition changes with each movement of the locking element between its release and blocking positions, the switch being electrically connected with the alarm, whereby the first switch monitors the position of the locking element; and a second switch connected to the alarm and responsive to the position of the dogging element so as to actuate the alarm when the dogging element is disengaged.

12. A security system according to claim 11 further characterized by a hinge having contactors on one leaf thereof and contacts on the other leaf, the contactors engaging the contacts when the hinge is closed; and wherein the switches are connected to the alarm through the contacts and contactors of the hinge.

13. A security system according to claim 11 wherein the solenoid has an axially shiftable armature and the second switch is aligned with and operated by the armature.

14. A security system according to claim ll further characterized by a hinge mounting the door on the door frame, the hinge having contacts on one leaf thereof and contactors on the other leaf, the contactors engaging the contacts when the hinge is closed; and wherein the two switches are connected to the alarm and the solenoid is connected to a source of electrical energy through the contacts and contactors of the hinge.

Claims

8. A security system for monitoring a door hinged to a door frame, said security system comprising a strike on the door frame; a lock on the door, the lock including a retractable latch bolt which is capable of projecting from the door into the strike to secure the door in a closed position, manually operable retracting means for retracting the latch bolt, means movable to a locked condition for dogging the retracting means so the retracting means cannot be manually operated to open the door, and auxiliary latching means movable between blocking and release positions for preventing retraction of the latch bolt when in the blocking position and for permitting retraction of the latch bolt when in the release position, the auxiliary latching means being responsive to the position of the door and being in the release position when the door is open; an alarm; a first switch connected to the alarm and monitoring the locking means such that the first switch changes condition as the locking means moves into and out of its locked condition and will actuate the alarm only when the locking means is out of its locked condition; a second switch connected to the alarm and operable by the auxiliary latching means such that the second switch changes condition with each movement of the auxiliary latching means between its release and blocking positions and will actuate the alarm only when the auxiliary latching means is in its release position; and means connected with the alarm and responsive to the door position for operating the alarm when the door is away from its closed position, said last named means being at the hinges for the door.

14. A security system according to claim 11 further characterized by a hinge mounting the door on the door frame, the hinge having contacts on one leaf thereof and contactors on the other leaf, the contactors engaging the contacts when the hinge is closed; and wherein the two switches are connected to the alarm and the solenoid is connected to a source of electrical energy through the contacts and contactors of the hinge.