WO1999066467A1

WO1999066467A1 - Intelligent interface between lock system and alarm system

Info

Publication number: WO1999066467A1
Application number: PCT/US1999/013367
Authority: WO
Inventors: William F. Brown, Jr.; Roy T. Abner
Original assignee: Sargent & Greenleaf, Inc.
Priority date: 1998-06-15
Filing date: 1999-06-15
Publication date: 1999-12-23
Also published as: AU4565699A

Abstract

An intelligent interface between a lock system and an alarm system (130) monitors the condition of various items related to the lock system and the area associated with it. The interface (200) monitors whether the lock bolt (100) is extended or retracted, whether an attempt is being made to open the door lock (124), whether the door guarding a protected area is open or closed (150), whether a motion detector (122) has detected an individual's presence, and so forth. The inventive interface intelligently (200) interprets the conditions that are input to it, reports status to the alarm system (130), controls other devices, and provides information to display devices (134). The interface's monitoring and intelligent interpretation (200) reduces occurrences of false alarms, such as when an authorized individual routinely unlocks the lock (100) after forgetting to disable the alarm system. Also, more appropriate control of other monitoring devices such as a video recorder (140) is provided, so that video images are recorded only during certain events of interest. The intelligent (210) controlled recording thereby minimizes the amount of storage required for the video recordings, and reduces the amount of time required for security personnel to locate an event of interest on the tape.

Description

INTELLIGENT INTERFACE BETWEEN LOCK SYSTEM AND ALARM SYSTEM

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to systems that monitor controlled- access areas. More specifically, the invention relates to an interface between a lock system and an external alarm system. The interface monitors the condition of various items related to the lock and the area around it, intelligently interpreting the conditions, reporting status to the external alarm system and providing control to external monitoring or information to display devices.

2. Related Art

Various lock systems are known in the art, some of which are used in conjunction with alarm systems. However, many of the interfaces between the lock system and alarm system are relatively unintelligent, causing various undesirable results.

For example, if certain alarm systems are not first manually disabled, an alarm condition is triggered whenever a lock is opened or whenever a door to a protected area is opened—even when the lock has merely been routinely opened by an authorized individual. Such false alarms can only be prevented if the individual remembers to disable the alarm system before opening the lock and door. Thus, there is a need in the art to provide a system that monitors the condition of a lock and the area around it, and indicates alarm conditions more intelligently, so as to minimize false alarms.

As another example of the shortcomings of known lock-alarm interfaces, certain alarm and monitoring systems are triggered whenever motion is detected in or near a protected area, such as outside a safe. In such systems, a motion detector directly causes the alarm system to react, such as by calling the police or performing some other alarm response. Conceivably, a motion detector could be used to cause a video tape recorder to begin recording events in the area. However, if the area outside the safe is a high-traffic area, hours of video tape would be recorded needlessly, because few or none of the individuals triggering the motion detector were even trying to gain access to the protected area. More primitive systems involve constant (albeit time-lapse) video recording, thus generating quantities of essentially contentless video recordings. In either of these scenarios, security personnel must store large quantities of video cassettes, and review hours of useless video recordings to find an occurrence of interest. Thus, there is a need in the art to provide a system that is intelligent enough to distinguish between routine, innocent occurrences and acts that actually threaten a protected area.

It is to provide more intelligent monitoring and reporting of the condition of a lock system and the area associated with it, and to thus satisfy these needs in the art, that the present invention is directed.

SUMMARY OF THE INVENTION

The invention provides an intelligent interface between a lock system and an alarm system. The inventive interface monitors the condition of various items related to the lock system and/or the area associated with it. such as, for example, whether the lock bolt is extended or retracted, whether an attempt is being made to open the lock, whether the door guarding a protected area is open or closed, and/or whether a motion detector has detected an individual's presence. The inventive interface intelligently interprets the conditions that are input to it, and reports status to the alarm system, and/or controls other devices or provides information to display devices.

Advantageously, the inventive interface's monitoring and intelligent interpretation reduces occurrences of false alarms, such as when an authorized individual routinely unlocks the lock after forgetting to disable the alarm system.

Also, the inventive interface allows more appropriate control of other monitoring devices such as a video recorder, which can be controlled to record a video image only during certain events of interest. This intelligently-controlled recording thereby minimizes the amount of storage required for the video recordings, and reduces the amount of time required for security personnel to locate an event of interest on the tape.

Other objects, features and advantages of the invention will be apparent to those skilled in the art upon a reading of the following specification in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is better understood by reading the following Detailed Description of the Preferred Embodiments with reference to the accompanying drawing figures, in which like reference numerals refer to like elements throughout, and in which:

FIG. 1 is a high-level block diagram illustrating a typical connection of an inventive interface 200 with a lock system, monitoring devices, display devices, and alarm system.

FIG. 2 is a hardware block diagram of the interface 200 according to a preferred embodiment of the present invention.

FIG. 3 is a high-level flow chart indicating major functional features performed by the inventive interface.

FIG. 4 is a high-level diagram indicating functions performed within the main loop 400 from FIG. 3.

FIG. 5 shows functional details of the key closure response routine 500 from FIG. 4.

FIG. 6 shows functional details of the bolt sensing routine 600 from FIG. 4.

FIG. 7 shows functional details of the VCR control routine 700 from FIG. 4.

FIG. 8 shows functional details of the bolt status delay routine 800 from FIG. 4.

FIG. 9 shows functional details of the alarm timer routine 900 from FIG. 4. FIG. 10 is a timing diagram of a typical sequence of events, illustrating a timing relationship of various signals in a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In describing preferred embodiments of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the design or selection of conventional elements such as microprocessors, level shifters, buffers, drivers, switches and the like, whose details are not essential to the claimed invention, are not included for the sake of brevity, it being understood that those skilled in the art, upon reviewing this specification and drawings, are readily able to make and use the claimed invention without undue experimentation.

FIG. 1 is a high-level block diagram illustrating a typical deployment of the inventive alarm interface 200. The illustrated alarm interface 200 is connected to a lock system (including elements 100 and 110), monitoring devices (such as elements 122 and 124), display devices (such as element 150), and an alarm system (such as element 130).

More specifically, the alarm interface 200 is shown connected in series between a lock 100 and its corresponding access control device 1 10 (such as a keypad unit with a keypad 112). The lock 100 and alarm interface 200 are preferably located on the back of a door 1 that separates a protected area 2 from an unprotected area 3. Access control device 1 10 may be located conventionally, on or beside the door 1 , accessible from area 3. It is understood that a keypad 1 12 is illustrated by way of example, and that the lock may be opened by any suitable means, such as a card reader, visual scanner, or other device for determining whether an individual is authorized to enter the protected area. In the illustrated embodiment, batteries within the keypad unit 1 10 provide power to the lock via a series of voltage and ground lines, labelled 1 17, 107 and 1 18, 108, respectively.

In an exemplary implementation, keypad unit 1 10 also provides data signals on data lines 1 15, 105 to lock 100. The data signals indicate which keys on the keypad have been pressed. In normal operation, a microcontroller in the lock 100 determines whether a sequence of numbers entered at the keypad matches a correct combination. If the sequence matches a correct combination, the lock retracts a bolt (not shown) that otherwise prevents the door 1 from being opened. The opening and subsequent extension of the bolt to re-close the lock may be performed in any conventional manner, and details thereof need not be included in this discussion.

The lock provides a beep/LED signal on lines 106, 1 16 to the keypad. This beep/LED signal causes a beeper or LED (not shown) on the keypad unit 1 10 to sound or to be illuminated, in response to a key closure, entry of an incorrect combination, low batteries, or other condition programmed into the lock^'s microcontroller. The lock can send differently- coded signals on the beep/LED paths 106, 1 16, to differentiate among the different conditions that are encountered.

The inventive interface 200 is preferably modular in nature, and can be inserted in-line between the keypad and lock using connectors 109 and 119. In a preferred embodiment of the interface 200, the lines 105, 106, 107, 108 are electrically connected straight through to lines 1 15, 1 16, 117, 1 18, respectively. In this manner, the alarm interface unit 200 may be inserted and removed without affecting the functioning of the lock system that includes lock unit 100 and keypad 1 10.

The lock 100 preferably includes one or more internal sensors that sense the position of the lock's bolt. In a preferred implementation, a first sensor is provided for sensing that the bolt has been extended (a "locked" condition), and a second, separate, sensor is provided for sensing that the bolt has been retracted (an "unlocked" condition). Each sensor may, for example, involve a magnet and a Reed switch mounted on opposite ones of the bolt and the lock casing; the magnets or Reed switches may be located on opposite extremes of the bolt travel so that the full extent of motion of the bolt can be detected. When the magnet and Reed switch are in close proximity, the Reed switch is in a first conductive state (open or closed), and when the magnet and Reed switch are not in close proximity, the Reed switch is in a second, opposite conductive state (closed or open).

The lock 100 provides two signals to the alarm interface 200, respectively indicating the conductive state of the two Reed switches to the alarm interface 200, on lines 101 , 102. Separate "extended" and "retracted" signals 101 , 102 are provided, despite the fact that they will normally be of opposite values. The implicit provision of what might be thought to be redundancy, provides enhanced monitoring in certain scenarios, such as when the bolt is stuck between its fully retracted and fully extended states.

To provide more intelligent monitoring of the lock system, data signals from the keypad unit 1 10 may be tapped from the data line passing through it, as may information from the beep/LED line from lock 100. This is in addition to the fact that the interface inputs the state of the "bolt extended" and "bolt retracted" indicators in lock 100.

Moreover, the inventive alarm interface 200 envisions that information from a variety of sources may be input, so as to monitor the condition of not only the lock system itself, but of other components as well.

For example, a motion detector 122, normally monitoring the unprotected area 3 near the door 1 to the protected area, provides a binary signal to the alarm interface 200 on path 123. Similarly, a door sensor 124 monitors whether or not the door 1 is physically closed or open, and provides a binary signal to the alarm interface on path 125. It is to be understood that the illustrated monitoring of lock system 100/110, motion detector 122, and door sensor 124 is exemplary, and should not limit the scope of the invention. Various other monitoring devices, and combinations thereof, are contemplated for use in conjunction with the inventive interface 200. In particular, the door sensor 124 may be directly connected to alarm system 130, although this direct connection avoids some of the benefits of having the inventive alarm interface 200 in place between them.

Preferably, the alarm interface 200 receives power from an external source such as alarm system 130 on path 160, although of course this is not a requirement of the invention. Based on its monitoring of the condition of the keypad, lock, lock bolt, motion detector, door sensor (and any other elements), the alarm interface provides several outputs, most of which are provided to alarm system 130.

Alarm system 130 may be of conventional design. Generally, such an alarm system 130 is connected to a control unit 132 that allows a user or other automated system to enable or disable the alarm system, or perform other programming tasks that the particular alarm system permits. Also, an alarm system normally operates with a display console 134 that provides visual or audible indications of the status of the alarm system or the area it protects. A common feature of alarm systems is an auto-dialer 136 that can telephone the police or a private security force in the event of an alarm condition. The alarm system can have many other components (not shown), including monitoring devices (such as motion detectors, still or video cameras, door position sensors, and the like), other display devices (local or remote), and other communication devices (such as a modem, audible or visible alarm, and so forth). In short, the details of the alarm system implementation are not essential to the inventive alarm interface 200, and further discussion not necessary.

The alarm interface 200 provides one or more bolt status indicator signals on paths 162. 164 to the alarm system 130, and are described in greater detail below. It is recognized that a single bolt status signal may be provided in place of the two bolt status indicator signals, since in normal operation they are almost always opposite in value.

Likewise, a "disarm/enable" signal is provided on path 166 to the alarm system. A "disarm" value of this signal indicates that the alarm system should not be recognizing an alarm condition (at least as far as interface 200 is concerned). Conversely, the "enable" value of the signal indicates that (as far as the interface 200 is concerned) the alarm system should be capable of recognizing an alarm condition associated with the interface.

What here constitutes an "alarm condition," and what actions the alarm system takes in the event of an alarm condition, depends on the particular alarm system in question. However, regardless of the implementation of the alarm system 130, the inventive alarm interface 200 provides more intelligently processed status information to the alarm system so that the alarm system's actions are commensurately more intelligent.

For example, a conventional alarm interface might signal an alarm condition any time door 1 is opened, requiring a user to remember to disable the alarm system each time before he opens the door routinely using the keypad 1 12. However, the inventive interface recognizes that opening the door using a proper combination entry at keypad 1 12 is a routine event that should not invoke an alarm condition, and, accordingly, the inventive interface does not signal an alarm condition when the door is sensed to be open after a routine correct combination entry.

The inventive interface also provides a VCR Control signal on path 168 to a visual image recording device such as video cassette recorder (VCR) 140. VCR 140 continuously receives video signals from (for example) a video camera 142 that normally views the unprotected area 3 immediately outside the protected area 2. When the VCR Control signal is activated, the VCR records the video signal form camera 142, but when the VCR Control signal is inactive, the VCR does not record. In this manner, the inventive interface can intelligently reduce the amount of time that the VCR is recording, thus reducing the demand to store video cassettes and minimizing the amount of time security personnel must review the tapes in order to inspect an event of interest. In a preferred embodiment, the inventive alarm interfaces activates the VCR Control signal for a period of time (such as ten seconds) after any key on keypad 112 is pressed (provided that the bolt extended at the end of the ten-second period). This activation of the VCR Control signal causes anyone attempting to tamper with the keypad to be captured on video tape, while minimizing the amount of video tape that is consumed by routine openings of the lock by authorized individuals.

It is envisioned that the inventive alarm interface can activate the VCR Control signal for given periods of time, in response to conditions than pressing of a key on the keypad (such as a signal from motion detector 122. a door sensor 124, or bolt retraction signal 102). However, as described with reference to the flow charts FIGS. 3-9, a preferred embodiment of the inventive interface is designed to avoid needless false alarms and unnecessary consumption of video tapes and inteφrets these other inputs appropriately before signalling the alarm system or VCR.

Referring again to FIG. 1 , the inventive alarm interface 200 also provides G and R indicator signals on paths 170. 172 to a lock status panel 150, which may be located near the door or, alternatively, in a remote monitoring post. Lock status panel 150 has green and red indicator LEDs 152. 154 that are illuminated in response to the G and R signals, respectively. Essentially, the G and R signals are provided when the lock's bolt is extended (to lock the door) and retracted (door unlocked), respectively. These two signals provide visual confirmation to the user of the lock (or the remote monitoring personnel) that the lock's bolt is either extended or retracted, or (in an unusual circumstance) between its extreme extended and retracted positions.

To allow the interface 200 to provide other information signals to output units other than lock status panel 150 lies within the contemplation of the invention. Likewise, the invention provides that the alarm interface can provide control signals to units other than a VCR 140. Accordingly, the illustrated embodiment should be inteφreted as illustrative and not limiting. FIG. 2 is a hardware block diagram of the alarm interface 200 according to a preferred embodiment of the present invention. An essential element of the alarm interface is a microcontroller, which may be a conventional microcontroller such as a MICROCHIP PIC16C62A that is installed, programmed, and operated in accordance with principles readily known to those skilled in the art. The microcontroller has several inputs from and outputs to the outside, via buffers and drivers that may be of conventional design.

The "bolt extended" signal on path 101 and the "bolt retracted" signal on path 102 pass through respective buffers 201, 202. Buffers 201, 202 may include, for example, a low-pass filter that smooths the signal and reduces the effects of electrostatic discharge, as well as a pull-up resistor. The motion detector signal on path 123 and the door sensor signal on path 125 pass through respective buffers 223, 225 that filter and condition the respective signals to make them compatible with the microcontroller's inputs. Further, a conventional opto-isolator 216 extends with a current-limiting resistor between +V on path 208 and the beep/LED signal on path 206 so that the microcontroller can recognize when a beep/LED signal is being sent, without interfering with the signal. A conventional regulator 260 provides an interface between the alarm system voltage signal 160 and the power input of the microcontroller.

Concerning the outputs of the microcontroller, a set of drivers 261 (which may be BS170 MOSFET drivers) are powered by power signal 160, and receives signals from the microcontroller. The drivers drive a corresponding set of switches 262, 264. 266, 268 that may be implemented as relays. Switches 262, 264, 266, 268 provide two Bolt Status Output signals 162. 164. disarm/enable signal 166, and VCR Control signal 168, respectively.

In a particular preferred embodiment, signal paths 162, 164, 166. 168 are actually implemented using two conductors each. The information is conveyed to the alarm system or VCR based on whether or not the corresponding relay 262, 264, 266. 268 is closed. Finally, the G and R signal paths 170, 172 may be driven directly, including only current-limiting resistors 270. 272 in-line between the microcontroller and the lock status panel.

A hardware implementation of a preferred embodiment of the present invention having been described above, the following is a description of the functional operation of the invention according to a preferred, non-limiting embodiment. FIGS. 3-8 are flow charts representing firmware that is programmed into microcontroller 210 (FIG. 2).

For clarity and ease of understanding, the flow charts refer to operation of the device at a high level of functionality rather than referring to non-essential details of implementation; for example, the flow charts refer to whether the "lock is locked" rather than to whether the '"bolt extended' sensor is closed." This is to emphasize that the functional operation of the device does not demand the particular hardware implementation that is described above, and that the scope of the invention should not be limited to disclosed embodiments.

FIG. 3 is a high-level flow chart indicating major functional features performed by the inventive alarm interface. After the alarm interface is powered up (at 310), an initialization routine 320 is executed.

In the initialization routine 320, after variables needed during subsequent processing are initialized, an interrupt service routine (ISR) is started. In the described embodiment, an ISR is used for timing-related functions, such as a VCR timer (ten seconds), an alarm timer (one second) and a bolt status delay timer (one-half second). Also, the ISR is used for pulsing relays properly, ensuring proper "debouncing" of the signals from the Reed switches in the lock, and detection of the (2 kHz square wave) beep/LED signal verifying that a key has been pressed. Also in the initialization routine, the alarm is enabled (via path 166), and the VCR is turned on (for the ten- second period of the VCR timer).

After the initialization routine 320 is completed, control passes to the main loop processing 400, which is described in greater detail in the high-level flow chart of FIG. 4 and the detailed flow charts of FIGS. 5-9. Referring now to FIG. 4. main loop 400 includes: a key closure response routine 500 (detailed in FIG. 5), a bolt sensing routine 600 (detailed in FIG. 6). a VCR control routine 700 (detailed in FIG. 7), a bolt status delay routine 800 (detailed in FIG. 8), and an alarm timer routine 900 (detailed in FIG. 9). In a preferred embodiment, the illustrated functions are made under control of microcontroller 210 (FIG. 2), which executes microinstructions that have been coded and stored in an internal PROM for execution. However, the implementation of the described functions is not intended to be limited to such an embodiment.

Although the routines are illustrated in a given order in FIG. 4, it is envisioned that the order in which the routines are executed may be varied in accordance with principles known to those skilled in the art. Further, it is envisioned that the functions performed by the routines may be performed in parallel rather than in series, depending on the hardware architecture of the system involved. Moreover, one or more of the described routines may be omitted, and additional routines may be included, while still remaining within the scope of the invention. Accordingly, it is to be understood that the following functional descriptions are made by way of illustration and do not limit the scope of the invention.

Referring now to FIG. 5, an embodiment of key closure response routine 500 is illustrated. Control enters the key closure response routine and a decision block 510 determines whether a key on the keypad unit 1 10 has been pressed. If it is determined that no key has been pressed, then control passes directly out of routine 500. However, if it is determined that a key has been pressed, control passes to block 520, which indicates that the alarm interface turns on the VCR 140 using a signal on VCR control path 168 (FIGS. 1 and 2). Then, in block 530, a VCR timer is set to an initial value (ten seconds in a preferred embodiment). Collectively, blocks 510, 520, and 530 ensure that, when a key on the keypad is pressed, the environment around the lock is recorded on tape by VCR 140 for a period of at least ten seconds (or some other predetermined length of time).

Referring now to FIG. 6, an embodiment of bolt sensing routine 600 is illustrated. Control enters the routine and a decision block 610 determines whether there has been a change in the position of the lock^'s bolt since the last time this decision block has been visited. If there has been no change in the position of the bolt (retracted-to-extended, or extended-to-retracted), then control pass directly out of routine 600. However, if it is determined that there has been a change in the position of the bolt, then control passes to a decision block 620.

Decision block 620 represents the microcontroller^'s determination of whether the bolt is being retracted. This may be determined by reading whether the "extend" signal on path 102 from the lock has just been deactivated. If it is determined that the bolt has not just been retracted (indicating that the lock is locked), then control passes directly to decision block 640.

If it is determined that the bolt has just been retracted, then control passes to blocks 622 and 624. Block 622 indicates the microcontroller's sending of a "disable alarm" signal on path 166 (FIGS. 1 and 2). and block 624 indicates the microcontroller's setting of an internal "alarm timer" to a predetermined time interval (one second in the preferred embodiment). The alarm timer ensures that, for the given time interval, the alarm system receives a disarm signal of sufficient duration to disable the alarm before receiving a bolt retraction signal, and does not treat a routine authorized bolt retraction as an alarm condition. This feature prevents false alarms when people fail to disarm the alarm system before unlocking the safe. After the alarm timer is set in block 624. control passes to decision block 640.

Decision block 640 indicates the microcontroller's comparison of the two signals received from the lock, the "extended" signal on path 101 and the "retracted" signal on path 102 (FIGS. 1 and 2). Three comparison results are possible, as follows. First, if the "retracted" signal is active but the "extended" signal is not active, this indicates that the bolt is retracted; in this event, control passes to block 642, in which the microcontroller repeatedly toggles the R signal on path 172 (FIGS. 1 and 2) and a red light flashes on the status board 150. Second, if conversely, the "retracted" signal is not active but the "extended" signal is active, control passes to block 644. this indicates that the bolt is extended; in this event, control passes to block 644, in which the microcontroller repeatedly toggles the G signal on path 170 (FIGS. 1 and 2) and a green light flashes on the status board 150. Third, if the two signals are the same, an anomalous or temporary condition is occurring; in this event, the R and G signals are alternately activated to cause both the red and green lights to flash.

After control passes from blocks 642 or 644 (but not block 650), control passes to block 646 which indicates the microcontroller's starting of a bolt status delay of a predetermined time duration (preferably half a second). During this time delay, the change of bolt status is inhibited from being sent on paths 162, 164. This feature also helps to prevent false alarms. After blocks 646 or 650, control passes from the bolt sensing routine.

Referring now to FIG. 7, an embodiment of VCR control routine 700 is illustrated. Control enters the routine and enters decision block 710. Decision block 710 indicates the microcontroller's determination of whether the VCR timer (set in block 520 in FIG. 5) has expired. If the VCR timer has not expired, control passes directly out of the VCR control routine 700 so that the VCR 140 (FIG. 1) continues to record.

If the VCR timer has expired, control passes to decision block 720, which reflects the microcontroller^'s determination of whether or not the bolt is extended. The microcontroller determines this by reading the "extended" input on path 101 (FIG. 1). If the "extended" signal is not active (indicating an unlocked condition), control passes directly out of the VCR control routine 700 so that the VCR continues to record if the lock is unlocked. If however, the "extended" signal is active (indicating the lock is locked), control passes to block 730. Block 730 indicates that the microcontroller deactivates the VCR control signal on path 168 so that, after the VCR timer has expired and the lock is locked, the VCR stops recording.

Referring now to FIG. 8, an embodiment of bolt status delay routine 800 is illustrated. Control enters the routine and enters decision block 810. Decision block 810 indicates the microcontroller's determination of whether or not the bolt status delay (set in FIG. 6 block 646) has expired. If the bolt status delay has not expired control passes immediately out of bolt status delay routine 800. However, if the bolt status delay has expired, control passes to block 820. In block 820, the microcontroller outputs on paths 162, 164 the bolt status, either locked or unlocked (as had been determined in FIG. 6 block 640) before exiting the routine. In this manner, the status of the bolt is not reported to the external alarm system 130 until after a given time period (such as a half-second) after the bolt is either retracted or extended. This half-second delay in reporting changes of the position of the bolt ensures that the alarm has adequate time to be disabled by a disarm signal on path 166, so that the bolt status does not erroneously trigger what the external alarm system 130 may wrongly consider to be an alarm condition.

Referring now to FIG. 9, an embodiment of alarm timer routine 900 is illustrated. Control enters the routine and enters decision block 910. Decision block 910 reflects the microcontroller's determination of whether or not the internal alarm timer (set in FIG. 6 block 624 to be one second) has expired. If the alarm timer has not expired, control passes directly out of the alarm timer routine. However, if decision block 910 determines that the alarm timer has expired (indicating the end of the exemplary one-second alarm timer interval), control passes to block 920. Block 920 indicates the microcontroller's activating of the alarm enable signal on path 166 (FIGS. 1 and 2).

The various timers involved in the above-described embodiment (VCPv timer, alarm timer, bolt status delay) may implemented in software, with an initial value stored in a RAM memory location and decremented periodically in response to an interrupt routine. Alternatively, an interrogate-and-decrement approach may also be used, in which a variable in RAM is checked during each iteration of a loop and decremented if the value of the variable is still greater than zero. Of course, any other implementation suitable to the puφose, such as repeated loop iterations or other electrical or electronic timers may also be used, as recognized by those skilled in the art. Accordingly, the particular manner of implementing the above-described functions is not essential to the invention that is claimed, and the scope of the invention should not be limited except by the language of the claims.

FIG. 10 is a timing diagram of a typical sequence of events, illustrating a timing relationship of various signals in a preferred embodiment of the present invention.

Referring to FIG. 10, the first trace 1010 illustrates a user's pushing of a sequence of keys to retract the bolt. The second trace 1020 illustrates how the bolt travels from its fully extended position 1021 to its fully retracted position 1022, where it remains for a given period of time (such as six seconds). At the end of the period of time, under typical circumstances, the bolt is automatically extended again, as shown at 1023.

The "extended" signal 101 (see also FIG. 1) is active only when the bolt is fully extended, shown at 1025. Likewise, the "retracted" signal 102 (see also FIG. 1) is active only when the bolt is fully retracted, shown at 1026. During the period in which the bolt is in transit between its extreme positions, neither signal 101 or 102 is active.

The VCR Control signal 168 (see also FIG. 1) is activated by the first key closure 101 1, and remains active (shown at 1068) for a given time period (such as ten seconds) after the last key closure 1012. This ensures that significant events are recorded without undue use of video tape.

The disable alarm signal 166 (see also FIG. 1 , and FIG. 6 block 622) is activated (shown at 1066) for a given time period (such as one second) after the "extended" signal 101 (FIG. 1) is deactivated. The bolt position signal (reflected in signals 162, 164 in FIG. 1) is activated (shown at 1064) a short time period (such as one-half second) after the "retracted" signal 102 is activated. The bolt position signal is deactivated the same short time period after the "extended" signal 101 is activated. In this manner, the signal indicating the position of the bolt is delayed by one-half second to allow the disable alarm signal 166 to prevent false alarms.

Modifications and variations of the above-described embodiments of the present invention are possible, as appreciated by those skilled in the art in light of the above teachings. For example, the particular inputs to and outputs of the alarm interface may be varied in different combinations. Also, the arrangement, implementation, and programming of components within the interface may be chosen to be other than those specifically disclosed, while still remaining within the contemplation of the invention. Moreover, a wide variety of lock systems and alarm systems may be used with the inventive interface without limiting its scope. The exact timing durations and relationships shown in the "typical" timing diagram of FIG. 10 may be varied while remaining within the scope of the invention. It is therefore to be understood that, within the scope of the appended claims and their equivalents, the invention may be practiced otherwise than as specifically described.

Claims

WHAT IS CLAIMED IS:

1. An interface between (A) an alarm system and (B) a lock system that includes (B 1 ) a bolt that extends to lock a door to a protected area and that retracts to allow the door to be opened and (B2) a bolt sensor that provides a bolt sensor signal indicating a position of the bolt, the interface comprising: a) a bolt sensor input that receives the bolt sensor signal from the lock; and b) means, responsive to the bolt sensor input, for sending the alarm system an alarm disable signal when the bolt sensor input receives a bolt sensor signal indicating that the bolt is being retracted, so as to prevent false alarms.

2. The interface of claim 1, wherein: the alarm disable signal is on the order of one second in duration.

3. The interface of claim 1, wherein: the bolt sensor signal includes a "bolt extended" signal and a "bolt retracted" signal; and the sending means sends the alarm disable signal in response to a transition of the "bolt extended" signal from an active state to an inactive state.

4. The interface of claim 1 , further comprising: means, responsive to the bolt sensor signal, for communicating a bolt position signal to the alarm system; and means for delaying communication of the bolt position signal to the alarm system by a time delay, so as to ensure that the alarm system has time to react to the alarm disable signal before the bolt position signal indicates that the bolt has been retracted.

5. The interface of claim 4. wherein: the bolt sensor signal includes a "bolt extended" signal and a "bolt retracted" signal; when the bolt is being retracted, the "bolt extended" signal transitions from an active state to an inactive state before the "bolt retracted" signal transitions from an inactive state to an active state; the sending means sends the alarm disable signal immediately in response to the transition of the "bolt extended" signal from the active state to the inactive state; and the communicating means communicates the bolt position signal to the alarm system in response to, but the time delay after, the transition of the "bolt retracted" signal from the inactive state to the active state.

6. The interface of claim 5, wherein: the time delay is about one-half second.

7. The interface of claim 4, wherein: the time delay is about one-half second.

8. The interface of claim 1, wherein: the sending means includes a microcontroller executing coded instructions.

9. An interface between (A) a visual recording device and (B) lock system that includes (Bl) a lock and (B2) an access authorization device that can be used by an individual to attempt to unlock the lock so as to gain entry to a protected area, the interface comprising: a) means for receiving a first signal that is activated whenever the individual uses the access authorization device; and b) means, responsive to activation of the first signal, for sending a "record" signal to the visual recording device, to cause the visual recording device to record visual images for a limited time period, to reduce use of the visual recording device to include times during and immediately after an individual is using the access authorization device.

10. The interface of claim 9, wherein the sending means includes: means for initiating the "record" signal immediately in response to a first use of the access authorization device.

1 1. The interface of claim 9, wherein the sending means includes: means for terminating the "record" signal a predetermined time period after use of the access authorization device ceases.

12. The interface of claim 1 1 , wherein: the predetermined time period is on the order of ten seconds.

13 The interface of claim 9, wherein the sending means includes: means for initiating the "record" signal immediately in response to a first use of the access authorization device; and means for terminating the "record" signal a predetermined time period after use of the access authorization device ceases.

14. The interface of claim 13, wherein: the predetermined time period is on the order of ten seconds.

15. The interface of claim 9, wherein the access authorization device is a keypad with keys that the individual can press, and the sending means includes: means for initiating the "record" signal immediately in response to a first pressing of a key in a series of one or more key pressings.

16. The interface of claim 9, wherein the access authorization device is a keypad with keys that the individual can press, and the sending means includes: means for terminating the "record" signal a predetermined time period after a final pressing of a key in a series of one or more key pressings.

17. The interface of claim 16, wherein: the predetermined time period is on the order often seconds.

18. The interface of claim 9, wherein the access authorization device is a keypad with keys that the individual can press, and the sending means includes: means for initiating the "record" signal immediately in response to a first pressing of a key in a series of one or more key pressings; and means for terminating the "record" signal a predetermined time period after a final pressing of a key in a series of one or more key pressings.

19. The interface of claim 18, wherein: the predetermined time period is on the order often seconds.

20. The interface of claim 9, wherein: the sending means includes a microcontroller executing coded instructions.