Abstract:
A security system adapted for use on an aircraft to prevent unauthorized access into a cockpit area of the aircraft via a cockpit door. The system includes a keypad accessible by individuals in a cabin area of the aircraft. A logic system is in communication with the keypad and also with a switch disposed inside the cockpit. Occupants of the cockpit, via the switch, have the ability to manually unlock the cockpit door, to deny the request for entry, or to do nothing, in which case the door will be automatically unlocked after the expiration of a predetermined time interval. A pressure sensor in communication with the controller allows the electronic door locking member to be automatically overridden, and the door immediately opened, in the event of a decompression condition occurring in the cockpit.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. patent application Ser. No. 10/100,227 filed on Mar. 18, 2002, presently pending, the disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to security systems, and more particularly to a security system adapted for use on a mobile platform such as an aircraft for preventing unauthorized entry onto the cockpit of an aircraft. 
     BACKGROUND OF THE INVENTION 
     At the present time there is an increasing need for controlling access to particular areas of mobile platforms. More specifically, there is an increasing need to control access to a cockpit of a commercial aircraft. Present day security systems often involve a simple lock or other system requiring the use of a key to unlock a door leading to a cockpit. However, such systems can be inconvenient for flight attendants who may need to periodically enter the cockpit area of an aircraft, such systems require a low force to open the door in case of decompression event. 
     Present day systems for preventing unauthorized access to the cockpit of a commercial aircraft through the use of a key can be forced open, and also can be foiled by an intruder if the intruder should gain access to the key. Accordingly, there is a strong need for a security system for preventing unauthorized access into a cockpit of a commercial aircraft which does not suffer from the above-described limitations. 
     More specifically, there is a need for a security system for use on a commercial aircraft which provides the pilot, co-pilot or other occupants of the cockpit a signal that entry into the cockpit is being requested. Such a system would ideally give the individuals in the cockpit an opportunity to make an assessment as to whether or not entry into the cockpit will be permitted either immediately, or whether entry should be denied. There is further a need for such a system which allows the pilot, co-pilot or other cockpit occupant to unlock the door separating the cockpit from the cabin area of the aircraft from a convenient location within the cockpit. Also required is the ability for the flight attendant to unlock the door after alerting the pilot and co-pilot for a pre-set time, in case the pilot and co-pilot are both incapacitated. 
     SUMMARY OF THE INVENTION 
     The above and other objects are provided by a security system in accordance with a preferred embodiment of the present invention. The security system is particularly well adapted for use in mobile platforms such as, but not limited to, commercial aircraft. The security system operates to lock a door which separates a cockpit from a passenger cabin area and to allow occupants of the cockpit to receive signals indicating that a request for entry into the cockpit has been made by an individual in the passenger cabin area of the aircraft. The system further enables an occupant of the cockpit to provide a signal to the system allowing immediate unlocking of the cockpit door, or to deny the request to unlock the door. 
     The security system preferably includes a pressure sensor. The pressure sensor causes the cockpit door to unlock when a difference in pressure between the cabin and cockpit is sensed. 
     The system generally includes a user input device which is accessible by individuals in the cabin area. In one preferred form the input device comprises a keypad. A controller incorporating a chime is disposed in the cockpit. The logic system communicates with a control device positioned for convenient use by persons in the cockpit, as well as with a lock operably associated with the cockpit door. In one preferred form, the control device comprises a multi position rotary switch. 
     In a preferred embodiment the multi position rotary switch provides three switch positions: an “AUTO” position, an “UNLOCK” position and a “DENY” position. An individual in the cabin area makes a request to gain entry to the cockpit by entering a predetermined access code into the keypad. It will be appreciated that the access code is a pre-programmed, restricted code that only individuals, such as flight attendants, would be apprised of in advance of entering the aircraft. When a correct access code is input to the keypad, the logic system generates an aural and visual annunciation within the cockpit apprising individuals in the cockpit that a request to enter the cockpit has been made. If the switch is in the AUTO position, the occupants of the cockpit have a predetermined time period in which to decide either to unlock the cockpit door or to deny the request to enter. If a decision is made to allow entry, the occupants may leave the switch in the AUTO position, in which case the logic system will automatically unlock the lock associated with the cockpit door at the expiration of the predetermined time interval. If the occupants decide that entry should not be permitted, then the switch can be moved to the DENY position. This signals the logic system that the request to enter is being denied. The logic system will immediately disable the keypad and prevent further entry signals from being generated within the cockpit for a predetermined time thereafter. If the occupants decide to grant immediate entry, then moving the switch to the UNLOCKED position sends a signal to the logic system that the lock to the cockpit door should be immediately unlocked. The logic system then sends a signal to a suitable device, such as a solenoid, that immediately unlocks the cockpit door. The UNLOCK position unlocks the door at any time and stops all ongoing visual and aural annunciations. 
     In one preferred embodiment the signal provided by the logic system is provided by a chime associated with a controller. The logic system also implements an intelligent series of time delays after a request for entry has been made at the keypad. When such a request has been made, the controller causes the chime to emit an audible signal to the occupants of the cockpit. The controller also simultaneously begins a first predetermined delay interval. If no action has been taken at the control device by any occupant of the cockpit at the expiration of the first predetermined delay interval, a second audible warning is provided by the chime and a second predetermined delay interval is commenced. At the end of the second predetermined delay interval, if still no action has been taken by any occupant via the control device to either admit or deny the request for entry, then the chime provides a continuous audible warning for a third predetermined time delay interval. At the end of the third delay interval the controller automatically sends a signal to the solenoid to unlock the lock to the cockpit door. A visual indicator also preferably flashes intermittently during the third delay interval further signaling that the cockpit door will be unlocked within a very short time if no action is taken. This operating scheme thus provides a short time period for the occupants of the cockpit to make an assessment as to whether the request for entry to the cockpit should be granted or denied. Conveniently, the door lock is automatically unlocked without intervention by the occupants of the cockpit provided the control device is in the AUTO position. The provision of both audible and visual signals virtually eliminates the possibility that the occupants of the cockpit will not realize that a request for entry has been made. It further allows automatic unlocking of the cockpit door unless an occupant of the cockpit intervenes through appropriate control of the switch. 
     It will be appreciated that the keypad described above does not have the capability under any circumstances to unlock the door lock of the cockpit door. The lock is controlled strictly by signals received from the switch provided in the cockpit. Accordingly, no amount of tampering with the keypad, or even the destruction of the keypad, can result in unlocking of the cockpit door once it is locked. Unlocking can be accomplished only via the multi position switch. 
     Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein: 
         FIG. 1  is a simplified block diagram of a security system  10  in accordance with a preferred embodiment of the present invention; and 
         FIG. 2  is a timeline of the three time delay intervals implemented by the controller of the system after a request to unlock the cockpit door is received. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses. 
     Referring to  FIG. 1 , there is shown a security system  10  for controlling access into a control center of a mobile platform. In the following description, the mobile platform will be referred to as a commercial aircraft and the control center will be referred to as the cockpit of the aircraft. It will be appreciated, however, that the system  10  of the present invention is equally applicable to non-moving structures where it is desired to closely control access to a sensitive area of the structure. It is anticipated that the invention may also find applications on other mobile platforms such as ships or even buses. The system  10  advantageously includes only a limited number of independent component parts making it easily retrofitable to existing commercial or other types of aircraft. 
     Referring further to  FIG. 1 , the system  10  generally includes a user input device in the form of a keypad  12  which is disposed in the passenger cabin area  13   a  of an aircraft  13 , and in one preferred location on a door post assembly  15   a  adjacent a door  15  of the aircraft  13  facing the passenger cabin area. However, the keypad  12  may be placed in virtually any location where it can be conveniently accessed by flight crew members who may need to gain periodic access to the cockpit  13   b  of the aircraft  13 . 
     The keypad  12  is in communication with a logic system  14 . The logic system  14 , in turn, is in communication with a control device  16 , a circuit breaker  18  and a door lock solenoid  20 . An ambient air pressure sensor  22  disposed in a cockpit  13   b  of the aircraft  13  communicates with the door lock solenoid  20  and the logic system  14 . The door lock solenoid  20  is operably associated with a door lock  26  for the cockpit door  15 , as will be described in greater detail momentarily. 
     The logic system  14  comprises a suitable controller, and more preferably an 8-bit controller. Advantageously, the controller  14  includes a chime  24  which is used to generate an audible signal within the cockpit  13   b  of the aircraft  13 . The control device  16  is also disposed in the cockpit  13   b  and may be mounted on an overhead panel, in an aisle stand panel or at any other conveniently accessible location in the cockpit  13   b.    
     In a preferred embodiment the control device  16  comprises a multi position rotary switch  28  having a first switch position  30  designated as the “AUTO” position, a second switch position designated the “UNLOCK” position and a third switch position  34  designated as the “DENY” position. The switch  28  comprises a manually engageable switch element  36  which is spring biased normally into the AUTO position. The switch element  36  can be moved momentarily into either the UNLOCK position or the DENY position. As soon as the switch element  36  is released, however, it is biased back to the AUTO position. An “UNLOCK” indicator light  38  is also disposed closely adjacent the switch  28 , as is a “LOCK FAILED” indicator light  40 . The UNLOCK indicator light  38  is illuminated when a predetermined access code has been correctly entered into the keypad  12 , as will be described in greater detail momentarily. The LOCK FAILED indicator light  40  indicates that the solenoid  20  has not unlocked the lock  26  of the cockpit door  15 . 
     The keypad  12  comprises a plurality of numeric keys  42  and an enter key  42   a , a first indicator light  44 , a second indicator light  46  and a third indicator light  48 . The first indicator light  44  preferably comprises a red LED for indicating that the door lock  26  is in a locked condition. Second indicator light  46  preferably comprises an amber LED which is illuminated when a user inputs the predetermined access code correctly via the keys  42  and  42   a . Third indicator light  48  preferably comprises a green LED which signals that the solenoid  20  has unlocked the door lock  26 . 
     The solenoid  20  includes a microswitch  50  for sensing the position of a plunger  20   a  of the solenoid  20 . Accordingly, the controller  14  can verify that the plunger  20   a  has been moved into the locked position when the solenoid  20  is energized. This provides an additional degree of security in the event the solenoid  20  fails and the plunger  20   a  is not moved into the “LOCKED” position. In such instance, the LOCK FAILED indicator light  40  will be illuminated by the controller  14  to provide an immediate visual indication of such a condition to the occupants of the cockpit  13   b.    
     The ambient air pressure sensor  22  is used to detect a drop in pressure in the cockpit  13   b  when the cockpit door  15  is closed. Such a condition might occur, for example, if the windshield of the aircraft  13  was broken. In such a situation, it would be necessary to immediately unlock the cockpit door  15  to prevent complete decompression of the cockpit  13   b . The pressure sensor  22  is thus used to detect a drop in pressure within the cockpit  13   b  and to immediately signal this event by deenergizing the solenoid  20 . 
     Referring to  FIG. 2 , a description will now be provided of the predetermined time delay sequence that is implemented by the controller  14 . “T 0 ” represents the instant that a user correctly enters the predetermined access code via the keypad  12 . This code preferably comprises a three to eight digit numeric code. It is provided to flight attendants or other individuals, prior to entering the aircraft, who may have a need to periodically enter the cockpit  13   b  while the aircraft  13  is in operation. Immediately after receiving the correct access code, the controller  14  causes the chime  24  to generate an audible signal represented by pulses  52 . Pulses  52  represent two “beeps” or other short duration audible signals which immediately apprises the individuals in the cockpit  13   b  that a request for access to the cockpit has just been made. At T 0 , a first predetermined delay interval is commenced which extends in to “T 1 ”. At T 1 , if the controller  14  has not received either in UNLOCK or a DENY command via the switch  28  (i.e., the switch  28  has not been moved to either of these positions), then the controller causes the chime  24  to again provide audible signals, represented by pulses  54 , to remind the occupants of the cockpit  13   b  that someone is requesting access to the cockpit. T 1  represents the expiration of the first delay interval and the beginning of a second delay interval. 
     At “T 2 ”, if the switch  28  still has not been moved out of the AUTO position during the second delay interval, then the controller  14  causes a third delay interval to be commenced. At T 2  the controller  14  causes the UNLOCKED indicator light  38  to be continuously illuminated and the chime  24  is caused to output a continuous audible alert, represented by waveform  56 , that the lock  26  of the door  15  will be unlocked within a very short time period if no operator action is taken via the switch  28 . At any time, an occupant in the cockpit  13   b  may move the switch element  36  of the switch  28  to the UNLOCK position  32 , which signals the controller  14  to turn off the chime  24  and the UNLOCKED indicator light  38 , as well as to command solenoid  20  to unlock the lock  26 . Also at any time during the first delay interval, the second delay interval or the third delay interval, an occupant in the cockpit  13   b  may move the switch element  36  to the DENY position  34 . This signals the controller  14  to turn off the chime  24  and the UNLOCKED indicator light  38 , and further inhibits operation of the keypad  12  for a predetermined time thereafter. This predetermined time may vary but is preferably for a time interval of between five minutes to thirty minutes. During this time, if an individual should again correctly enter the access code into the keypad  12 , no audible or visual signals would be provided by the chime  24  or UNLOCKED indicator light  38 . After the expiration of this time period, then the user may again input the access code into the keypad  12  and make another request to access the cockpit  13   b.    
     At T 3 , as long as no operator selection has been made via the switch  28  (i.e., meaning that the switch element  36  has remained in the AUTO position  30 ), the controller  14  causes the solenoid  20  to be deenergized. This causes the door lock  26  to be unlocked. Thereafter, manual actuation of the door handle of the cockpit door  15  will allow the door to be opened. 
     In the preferred embodiment described above, the delay interval between T 0  and T 3  is user programmable from about 15 seconds to about 120 seconds in 15 second increments. Preferably, the delay interval between T 2  and T 3  has a minimum duration of at least 10 seconds. The audible signals represented by pulses  52  and  54  preferably comprise 0.5 second duration audible signals having a frequency of preferably around 500 Hz at approximately 75 dB. It will be appreciated, however, that the duration, frequency and intensity of these audible signals may be modified to suit user preferences. 
     The UNLOCKED indicator light  38 , when flashing during the third delay interval, preferably flashes at a 50% to 60% duty cycle, with 60% being the more preferred duty cycle. Again, however, the frequency at which this light flashes may be tailored to suit user preferences. 
     When the lock  26  of the cockpit door  15  is unlocked at point T 3 , the door is preferably maintained in the unlocked position for a predetermined time interval, and more preferably for at least about five seconds. Again, this delay interval could also be modified. During this time period the solenoid  20  remains deenergized. After this short time interval expires, the controller  14  again automatically energizes the solenoid  20  to cause the lock  26  to lock the door  15 . 
     The access code is preferably changeable from the controller  14 . This is accomplished by engaging a “PROGRAM” key  58  on the controller  14  as indicated in  FIG. 1 . Once this key is depressed, a new access code can be entered at the keypad  12 . 
     Another optional feature which may be implemented is a “door bell” mode. This mode may be implemented by selecting a particular key, such as the “1” key on the keypad  12 , followed by the “ENTER” key  42   a . This causes the chime  24  to generate an audible signal but does not begin the time delay period represented between T 0  and T 3 . In effect, the occupants of the cockpit  13   b  are simply apprised that an individual in the cabin area  13   a  of the aircraft  13  is requesting access to the cockpit. The audible signal may comprise one or more short duration signals by the chime  24 . 
     The system  10  of the present invention thus provides a means by which individuals in the cabin area of the aircraft can request access to the cockpit, and can further initiate a process by which a locked cockpit door will be automatically unlocked if no intervention is taken by occupants of the cockpit. The inclusion of the pressure sensor also ensures that in the event of a decompression condition occurring in the cockpit, the cockpit door will be automatically and immediately unlocked so that the door can be quickly opened. Importantly, the system  10  provides the occupants of the cockpit with the ultimate authority to deny the requested access if circumstances are such that the cockpit occupants believe that the cockpit should remain secure from all individuals in the cabin area. 
     Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.