Abstract:
A seismic sensor controlled door unlocking system which has a vibration sensor and a control system. The vibration sensor is configured to detect heavy vibrations such as those made by an earthquake. The control system maintains the locked state of, and has the ability to unlock, a door to which it is connected. Upon detection of a large vibration by the vibration sensor, the control system unlocks the door.

Description:
FIELD OF THE INVENTION  
         [0001]    This invention relates to a vibration sensor for detecting vibrations resulting from an earthquake, a bomb explosion or other vibration inducing disasters, and a control system connected to the vibration sensor which can cause a locked door to be unlocked when the sensor detects heavy vibrations from, for example, an earthquake. The vibration sensor is an inexpensive device which can be manufactured with standard off-the-shelf parts for simplicity, and comprises mostly mechanical parts (as opposed to electrical parts) to ensure dependability and long life of the vibration sensor. The vibration sensor is also housed in a control box which contains a backup battery, door lock control circuitry and a power regulator.  
         BACKGROUND OF THE INVENTION  
         [0002]    Vibration sensors such as seismic detectors are well known. These devices are used to detect vibrations from an earthquake, and produce an electrical signal indicative of the seismic activity detected over a period of time. These types of devices only record a time period of the event, and do not produce a control signal to a further device such as a fluid valve. Also, these devices are very accurate, and as such are very expensive.  
           [0003]    U.S. Pat. No. 3,359,538 to Raphael shows a pendulum type seismograph having a suspension cable  6  connected at one end to a pendulum  5 , and a driving magnet  9  fixed to a base below the swinging pendulum. Movement of the pendulum about the coil around the magnet causes a current to develop in the coil  19 , which is then recorded on a voltmeter  22 . The seismic detector of Raphael is used only to record the seismic events.  
           [0004]    U.S. Pat. No. 3,813,505 to Shoji shows a sensing device of acceleration and vibration which uses a seismic detector connected to an operating system for actuating a valve, cock or a switch in order to avoid a danger. The actuating device can open or close a valve in a gas line in order to prevent the flow of gas in a pipe that could be damaged by an earthquake. Broken gas lines have been known to cause great fires just after an earthquake.  
           [0005]    U.S. Pat. No. 4,012,611 issued to Petersen shows a seismic switch for a door alarm, the switch includes a permanent magnet supported by a swinging pendulum. A magnetic reed switch is positioned below the magnet and produces an open circuit in the reed switch. When the magnet is displaced, the reed switch is closed, forming a closed electrical circuit. The closed electrical circuit is used to activate an alarm.  
           [0006]    U.S. Pat. No. 5,694,867 issued to Diaz-Lopez (herein incorporated by reference) shows a security door system used in a bank, where the system includes two locking doors separated by an access chamber in which a metal detector is locked. The second door is usually locked to prevent a person from entering the bank. The second door is only unlocked when the metal detector detects no metal object such as a gun, and when the first door is locked. A power supply box includes an uninterrupted power supply and the control circuitry that is used to control the security door system, and is to be mounted to a wall. In this patent, if an earthquake or an explosion (such as from a bomb) was to occur, people from the bank could not escape because the door or doors would be locked. Thus, people could be trapped in the building. A bank employee could activate an emergency switch that would over-ride the system and open all locked doors, but the system would not then be fully automatic. If the bank personnel was incapacitated because of the vibration producing event such as a massive bomb explosion or earthquake, that person may not be capable of activating the over-ride to unlock the door or doors. Some systems which use electromagnetic locks include a 30 second time delay which unlocks the lock 30 seconds after a person pushes on the door. The purpose of the delay is to notify authorities that the normally locked door is about to be opened. This 30 second delay system would produce much panic if an explosion was to occur and people tried to rush out the door. The extra 30 seconds could mean the difference between life and death.  
           [0007]    Thus, there is a need in the prior art door locking systems for a device in which potentially damaging vibrations caused by an earthquake or explosion can be sensed, and a control system which will use the sensed vibrations to unlock a door for emergency escape of occupants.  
         BRIEF SUMMARY OF THE INVENTION  
         [0008]    It is an object of the present invention to provide for an inexpensive vibration sensor that does not need to be as accurate as the present technology would allow, but could be manufactured using simple, off-the-shelf parts such that an inexpensive vibration sensor could be produced so that use of a large number of the sensors would be economically feasible.  
           [0009]    It is another object of the present invention to provide a vibration sensor that can be easily checked to determine if the sensor is functioning properly.  
           [0010]    It is another object of the present invention to provide a vibration sensor that can be easily adjusted and accurately checked.  
           [0011]    It is another object of the present invention to provide for a vibration sensor in communication with a normally locked door such that when a vibration induced event occurs (such as an earthquake or bomb explosion), the normally locked door is unlocked to allow escape through the door.  
           [0012]    It is another object of the invention to provide for a compact power control box in which all the battery backup, control circuitry and seismic sensor is located. The control box can be mounted in a secure area of the building away from the doors to prevent tampering therewith, and the box and its contents are mounted to a rigid wall or column of the building in order to insulate the seismic sensor from non-threatening vibrations such as vibrations from the door system or from heavy trucks passing by.  
           [0013]    The objects of the present invention are realized in that the vibration sensor is comprised of a pendulum having a magnet connected at a bottom end of the pendulum, a normally opened magnetic contact switch located in a fixed position near the bottom of the swinging magnet, and a relay switch located near the magnetic contact switch to maintain the contact in an opened position after the vibration inducing event has ceased. The vibration sensor is also connected to a locking control system for a door such that the normally locked door can be unlocked automatically when the vibration sensor detects a vibration above a specified level. The vibration sensor is mounted in a lock box along with the battery backup power supply, the voltage converter, the electrical circuitry, and the fuses. The box is secured to a rigid structure of the building at a location away from the doors to prevent tampering and insulate the seismic sensor from non-threatening vibrations. The vibration sensor is mounted in a hollow metal box which is closed on both ends by plastic caps. A front face of the metal box has an opening and a glass plate covering the opening so that the pendulum can be viewed from outside. The pendulum includes a threaded weight can be adjusted along the pendulum. The weight has a marking thereon, and the inside of the box includes a scale in which the marking on the weight can be aligned in a plurality of positions in order to adjust the sensitivity of the pendulum. The vibration sensor includes a green LED and a red LED which is used to check if the sensor is functioning properly. In one embodiment, a relay switch is secured to a side of the metal box, while in another embodiment the relay forms the bottom cover for the metal box. 
       
    
    
       [0014]    Other objects, features and advantages of the present invention will become apparent from a consideration of the following detailed description, and from the accompanying drawings.  
       BRIEF DESCRIPTION OF THE DRAWINGS  
       [0015]    [0015]FIG. 1 shows the vibration sensor.  
         [0016]    [0016]FIG. 2 shows the vibration sensor in use with a door system.  
         [0017]    [0017]FIG. 3 shows an electrical circuit with the vibration sensor and the relay switch connected to a magnetic lock.  
         [0018]    [0018]FIG. 4 shows a control box in which the seismic sensor is placed therein, along with the battery backup and control circuitry.  
         [0019]    [0019]FIG. 5 shows an electric circuit diagram for a seismic sensor used in a control system to lock a door.  
         [0020]    [0020]FIG. 6 shows the seismic or vibration sensor with a glass window covering the front.  
         [0021]    [0021]FIG. 7 shows the magnet and pendulum assembly of the vibration sensor.  
         [0022]    [0022]FIG. 8 shows the seismic sensor with the adjustment scale, and the relay switch mounted on the side. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]    [0023]FIG. 1 shows the seismic or vibration sensor  10  formed of an aluminum box  11 , a top plate  19  secured to the box  11 , a pivot point  12  secured to the underside of the top plate  19 , a threaded rod  13  is connected to the pivot point  12 , a permanent magnet  14  is connected to the other end of the wire  13 , a bottom plate  16  is mounted on the bottom end of the box  11 , a normally opened magnetic contact  15  mounted on the bottom plate  16  so as to be near to the permanent magnet  14  but not in physical contact therewith, and wires  17  and  18  extending through a hole or holes in the bottom plate  16 . The box  11  is preferably made of aluminum, but can be made of any material (I.e. metal or plastic) which would support the components. The top  19  and bottom  16  plates are made of a hard plastic material.  
         [0024]    The wires  17  and  18  are connected to a relay board  25 . The relay board  25  is a well known component, model number ASRB-1 made by Advanced Signaling Company of Arlington, Tex. The relay board  25  could also be RSBN- TTL ultra sensitive relay module of Advanced Electronic Technology of Brooklyn, N.Y. The normally opened (NO) magnetic contact switch  15  is used to detect for vibrations from an earthquake or bomb explosion. The magnetic contact  15  is a well known device made by ADI of Syosset, N.Y., having model number SR-1075/BR. The relay board  25  can also be one made by Advanced Signaling Company of Arlington, Tex., model number ASPR-1X5 relay board. The vibration sensor  10  is secured to a fixed location in which the vibration is to be monitored therefrom. If the vibration sensor is used to unlock a door in a bank building, the sensor could be mounted to a concrete wall or column of the building. A typical vibration level in which the vibration sensor would be set is about 0.1 or 0.2 gravities (or 0.2 g). A gravity of 1 g is equal to the weight of the object, and means that a force equal to the weight of the magnet would be required to displace the magnetic beyond the required distance to change the position of the magnetic contact switch  15 .  
         [0025]    In operation, when a vibration induced event such as an earthquake or a bomb explosion occurs above a specified seismic level, the magnet  14  starts to swing about the pivot point  12 . When the magnet is displaced sideways beyond a specified distance, the contact switch opens and an electrical connection is broken between wires  17  and  18 . The purpose of the relay board  25  is to maintain the electrical connection when the magnet  14  swings back over the contact switch  15 .  
         [0026]    [0026]FIG. 2 shows the vibration sensor  10  used in a normally locked door  22  of, for example, a building. The door uses a magnetic lock  21  or any other well known locking device that can automatically lock and unlock a door. Magnetic locks generally are operated on low voltages, such as 12 or 24 volts DC. A terminal board  33  such as the one produced by Securitron (model number CCS4-12 or CCS4-24) and the seismic relay board  25  supply and control the power to the magnetic lock  21 . When a vibration inducing event, such as an earthquake, occurs, the power from a power source  32 —which is used to activate the magnetic lock  21 —is interrupted by the magnetic contact switch assembly  14  and  15 , and the magnetic lock  21  is deactivated or unlocked so that the door can be opened for people to escape from the building.  
         [0027]    [0027]FIG. 3 shows the vibration sensor used with the relay board  25 . The magnetic contact switch  15  is connected to a ½ amp fast blow fuse  26 . The fuse  26  will prevent the contact switch  15  from being welded closed if a short occurs in the electrical system. If the magnetic contact switch  15  is welded closed, then the system will not function as a vibration sensor. The fuse  26  is connected to the P(−) terminal of the relay switch  25 . A buzzer  36  is also connected to the relay switch  25  and to a Normally Closed reset switch  23 . Also connected in series with the buzzer  36  is a green light  38 . When the green light  38  is on, the system is operating properly. A red light  37  is connected in parallel with the buzzer  36 . The red light  37  can be mounted on the bottom portion of the vibration sensor  10  near the contact switch  15 . When the red light  37  is on, the system is not functioning properly. Pushing the reset switch  23  will reset the system for proper operation if the contact switch  15  is operating properly (is not welded together).  
         [0028]    Once the system is installed, it needs to be activated. With power connected, the normally closed reset switch  23  is pushed, providing power to the relay switch  25 . This initial power energizes a coil (located between the P+ and P− terminals) in the relay switch which maintains an electrical connection from the power source  32  to the magnetic lock  21 . Thus, the magnetic lock is activated or locked. When a vibration above a specified level occurs, such as when an earthquake or bomb explosion occurs, the magnet  14  in the vibration sensor  10  will be displaced beyond a specified distance, the contact switch  15  opens and an electrical connection between wires  17  and  18  is broken. When the contact switch  15  is open, power to the magnetic lock  21  is interrupted, and the magnetic lock  21  is released. When the vibration ceases, the relay switch  25  prevents power from being supplied to the magnetic lock  21  until the reset switch  23  is again depressed. Thus, the door  22  will not be re-locked when the vibration from the earthquake or explosion ceases or drops below the specified level to activate the vibration sensor  10 .  
         [0029]    A normally opened magnetic contact  15  is used to detect for vibrations from an earthquake or bomb explosion. The magnetic contact  15  is a well known device made by ADI of Syosset, N.Y., having model number SR-1075/BR. The magnet  14  is suspended by a threaded round bar  13  so that a vibration will displace the magnet. The pendulum bar  13  is threaded on its outer surface to allow a weight  35  to be positioned along the bar  13 . The weight  35  has a hole passing through the axis, and is threaded to be engaged with the threads on the bar  13 .  
         [0030]    The purpose of the relay switch  25  is to prevent the power from re-supplying the magnetic locks after the vibrations have stopped. If a bomb was to explode, when the vibration ceases, it is not desirable to re-lock the magnetic locks because people will still need to exit the building. The sensitivity of the magnetic contact can be adjusted by displacing the magnet  14  from the contact  15 , by using a heavier magnet, or adding moving the weight  35  along the bar  13 . Changing the position of the weight  35  along the bar  13  will change the moment of the pendulum. This change will effect what force or vibration is required to displace the magnet  14  such that the reed switch  25  is changed from its normal position,  
         [0031]    The vibration sensor  10  (or seismic detector) is preferably sealed within a metal box  11  as shown in FIG. 1. The top  19  and bottom  16  of the sensor  10  is made of plastic, but could be made of other materials such as metals.  
         [0032]    The vibration sensor  10  could also be an off-the-shelf type seismic detector, but this is a costly instrument. The preferred embodiment uses the vibration sensor  10  because of its simplicity and low cost of obtaining off-the-shelf parts.  
         [0033]    Other uses of the vibration sensor  10  could be for controlling valves in gas lines. The closed contact on the relay switch  25  could be connected to a motor which shuts gas valve when the quake occurs.  
         [0034]    [0034]FIG. 4 shows a regulated power supply box  40  which is used to supply power to a magnetic lock system. Inside the box is stored a regulated DC power supply module  32 , a terminal and fuse board  33 , a seismic sensor board  25 , 12 volt or 24 volt backup batteries  46 , and the seismic or vibration sensor  10 . The box  40  has a door  41  which can be locked to prevent unauthorized entry. The reset switch  23  and the green light  38  are preferably mounted on the door  41  so that they are accessible from the front of the door  41 . An outside power source such as the 110 volts AC from the main power lines is connected to the DC power supply module  32 , which reduces the voltage to 12 or 24 volts DC for use with the door system. If the main power is lost, the backup batteries  46  supply the power needed to control the door  22 .  
         [0035]    Placing the seismic sensor  10  inside the regulated power supply box  40  provides several benefits. One is that the seismic sensor  10  can be placed close to the circuitry in which the seismic sensor  10  is to have an effect when an earthquake or the like occurs. The box  40  is also to be mounted to a rigid wall or column  43  of the building so that the box and its contents are far away from the door system in order to prevent tampering. Placing the seismic sensor  10  in the box  40  also prevents unauthorized access or tampering with the seismic sensor  10 . Also, the seismic sensor  10  will not be effected by non-threatening vibrations such as movement from the door or a passing vehicle if the box  40  is secured to a rigid structure.  
         [0036]    The vibration sensor  10  is shown in FIG. 5 in a system used to control a door lock. A door  22  is secured in a structure, and a magnetic lock  21  is associated with the door  22 . A fuses and connector panel  33  (serial number CCS-4 made by Securitron Magnalock Corporation of Sparks, Nev.) is electrically connected to the backup battery pack or packs  46 . The battery pack  46 , the fuses and connectors panel  33 , the relay switch  25 , the reset switch  23  and the vibration sensor  10  are all contained within a control box for safe storage. A 120 VAC source  34  supplies power to the fuses and connector panel  33 . A 12 or 24 volt DC power source  32  used to convert 110 volt AC to 24 volt DC is connected to a reset switch  23  and to the relay switch  25 . One terminal of the magnetic contact  15  of the vibration sensor  10  is connected to the R4 terminal of the fuses and connector panel  33 , while the other terminal from  15  is connected to the relay switch  25 . In the embodiment shown in FIG. 5, the magnetic contact switch  15  is a double pole single throw contact. The second contact points are used for a second light to indicate the status of the contact switch  15 . A ½ amp fast blow fuse  26  is used in this wire. When the vibration sensor  10  detects an earthquake above a certain level, the system will deactivate the magnetic lock  21  to allow the door  22  to be opened. The door  22  can be one of several doors used in an access control vestibule, or a single door such as a fire escape which is kept locked and only opened in an emergency. The system can also be used to control operation of things such as escalators. When an earthquake or bomb explosion is detected, the power to the escalator can be shut off to disable the escalator.  
         [0037]    The vibration or seismic sensor  10  is shown in FIG. 6 with a front plate  49  having a cutout portion  47  therein so that the inside contents of the sensor  10  can be easily viewed. A transparent plastic or glass plate  27  is secured to the front plate  49  of the sensor  10 , over the cutout portion  47 . A small hole  29  in the glass plate  27  is used so that a probe can be inserted such that the magnetic  14  can be displaced to test the system in operation. A large hole  28  is also in the glass plate so that the red light  37  (and the green light  38  if used) can be placed therein. The glass plate  27  preferably has four small holes positioned at each respective corner so that the plate  27  can be secured to the front plate  49  by screws.  
         [0038]    The pendulum or bar  13  of the sensor is shown in FIG. 7. The pendulum  13  is a solid piece of stainless steel (the preferred mode) or brass having threads on the outside. A weight  35  with a hole through the axis also has threads to engage the threads on the pendulum  13 . The weight  35  can be positioned along the pendulum  13  by rotating the weight. The weight includes a marking  60  thereon (see FIG. 8) and the inside of the box includes a scale  63  marked thereon. The scale  63  is also visible through the opening  47  of the front face  49  of the box. The weight can be accurately adjusted along the pendulum by aligning the marking  60  with the scale  63 . A magnet  14  is secured to a plastic holder  48  which is secured to the pendulum  13  by a compound such as epoxy. The top of the pendulum  13  is connected to an eye-bolt  56  by way of a nut  55 . The eye-bolt  56  includes threads that can be screwed into the nut  55 . Another eyebolt  57  is engaged with the first eye-bolt  56  to form a pivot point for the pendulum  13 . The second eye-bolt  57  passes through a hole in the top plate  19 . A nut  58  secures the second eye-bolt  57 —and thus the pendulum assembly—to the top plate  19 . The space or distance between the magnet  14  and the contact switch  15  can be adjusted by adjusting the nut  58  on the second eye-bolt  57 .  
         [0039]    The preferred embodiment of the seismic sensor  10  is shown in FIG. 8. The metal box used to make the sensor is preferably made of aluminum, and is 2 inches by 2 inches in cross-sectional shape and 10 inches in length. Plastic strips  54  are mounted to the top and bottom ends of the sensor on the back side of the box, and are used to secure the sensor into position. The strips  54  are preferably made of a hard plastic of about ⅜ inch thickness, and have holes  55  to accept mounting screws. Secured to the side of the box is a second box  62  used to contain the buzzer  36  and the relay board  25 . A wire cable  65  exits through one hole formed in the bottom of the second box  62 , and contains the wires  17  and  18 , and two other wires. The second box  62  also includes holes for the red light  37  and green light  38  used to determine the status of the sensor. When the green light is on, the sensor is ready for operation. When the red light is on, the contact switch is in the closed position. When the sensor is operating properly, the green light should be on and the red light should be off when the magnetic  14  is over the contact switch  15 . When the special tool is used to displace the magnet  14  so that the contact switch  15  is closed, the green light would turn off and the red light would turn on.  
         [0040]    In another embodiment of the invention, the sensor  10  can have the relay switch  25  formed integral with the bottom plate  16 . The relay switch is of such size that it can be used as the bottom plate  16 . This embodiment would provide for a compact seismic or vibration sensor which includes the relay switch  25 . The magnetic contact switch  15  would be mounted on the top of the relay switch  25  such that the contact  15  is positioned near the magnet  14 .  
         [0041]    In conclusion, it is to be understood that the present invention is not to be limited to that precisely as described herein and as shown in the accompanying drawings. More specifically, the invention could be adapted to provide security for any secure area such as a bank vault, jewelry store, prison, or other security buildings. Further, the entrance chamber as disclosed herein may be employed to control access to the secured area, and other exit-only arrangements may be provided, for example, of the general type used is subway exits using a one-way revolving door type assembly having interlocking bars to prevent entry. Accordingly, the present invention is not limited to the arrangements precisely as shown and described herein.