Abstract:
A number of remotely located locked devices (26 and 27) are selectively operated by sending signals from a central supervisory location (28) through the telephone network (27) to a telephone set 32 and a converter (44) installed at each remote location. Initiating call signals from a remote telephone set are automatically generated and routed through the telephone network to a supervisory telephone set equipped with a standard 0-9 digit dial plus a special pushbutton (34) for generating a special signal. Receipt of the special signal at a calling remote station disconnects the remote telephone set and conditions a stepping circuit (74-86) and a sequence circuit (81-82) for subsequent operation upon receipt (88-104) of a predetermined sequence of 0-9 digit signals. Upon receipt of the predetermined sequence of signals within a first set time period, the stepping circuits and the sequence circuits are operated to generate (111) a signal that releases the locked device for a second set time period.

Description:
FIELD OF THE INVENTION 
     This invention relates to a system for selectively controlling a number of locked facilities at a number of diverse remote locations and, more particularly, to a system utilizing a commercial telephone network for the transmission of lock control signals between a central controller telephone set and telephone sets at the remote locations. 
     BACKGROUND OF THE INVENTION 
     Over the years a number of systems have been developed and installed for selectively controlling the entry into a locked building, e.g., apartment houses, through the use of telephones located in a number of rooms along with an auxiliary control and switching units for communicating with individuals seeking entry and for controlling the release of the lock. 
     Several of these systems, such as disclosed in U.S. Pat. No. 3,917,911 issued Nov. 4, 1975 to J. M. Lesher, U.S. Pat. No. 3,947,641 issued Mar. 30, 1976 to A. E. Trell and U.S. Pat. No. 4,113,986 issued Sept. 12, 1978 to G. F. Clement et al., use commercial telephone central offices to establish selective communication and control paths between tenants and a visitor seeking entry through a single locked door. 
     Other systems have been developed for selectively controlling access through a number of locked gates. One such system known as the Affirm Facility Management Systems manufactured by the Western Electric Company, Incorporated, New York, N.Y., utilizes an on-line card to limit entry by person, building, time of day and day of week. To gain admission, an encoded identification cards is inserted in a card reader at a particular one of a number of entrances to a building. The reader scans the card and transmits the data to a local control unit which determines whether the card holder should be admitted through that entrance, at that time and on that day. The data base for these control functions stores several thousands admittance data and can be readily updated. 
     There is still a need for a rather simple security system for selectively releasing locked devices for facilities at a number of remote locations under the control of an operator stationed at a central office. In a system of this type, the controller operator executes the necessary control functions through the agency of a conventional telephone network. In such a system the control should be attained by pushbutton dialing a sequence of multifrequency call number signals which are utilized to effectuate the selective release of the locked facility to which a person is seeking entry. This system should also include the capability of limiting the time that the locked device is released so that the person must enter the facility during this time, otherwise the controls revert to an original condition. In addition, such a system should also place a limit on the time available for the controller to dial the distinct number sequence indicative of a particular location to which the person is seeking entry. 
     SUMMARY OF THE INVENTION 
     This invention contemplates, among other things, a system for selectively releasing lock devices at a plurality of remote locations through multifrequency signals transmitted through a telephone central office which are generated by a controller at a central telephone set. The controller operates the telephone set pushbutton dial to generate a special signal which conditions sequence circuits at the remote locations so that subsequent dial multifrequency signals actuate one of the sequence circuits to release the lock device at one particular remote location. 
     More particularly, a person seeking entry to a locked facility at a remote location picks up a telephone set receiver to initiate the operation of an automatic multifrequency dialer which sends the call number of controller&#39;s telephone set through a commercial telephone office to establish a communication path between the entry-seeking person and the controller The person identifies himself to the controller who thereupon initiates the dialing of three multifrequency signals to release the lock device at the remote location for a predetermined period of time during which the person must enter the facility and after which the lock device is restored to an initial locking condition. The first multifrequency signal is converted to a binary coded digital signal to actuate a timing circuit which performs a number of functions, one of which is the setting of a time period in which the controller must pushbutton dial the next two signals indicative of the particular remote location. 
     At each remote location there is provided a multifrequency signal converter which acts to convert each received signal to a binary coded signal. The first binary coded digital signal operates the timing circuit which performs an additional function of conditioning a stepping circuit and a sequence circuit. The two-step circuit is operated upon receipt of subsequent multifrequency signals to operate the sequence circuit which is conditioned in accordance with the receipt of the proper two number sequence of dial signals. The correct operation of the sequence circuit operates a second timing circuit to release the lock device at the remote location. It may be appreciated that the first timing circuit only conditions the other circuits for a predetermined short period of time during which the controller at the central office dials the correct two number dial sequence in order to release the lock device at the remote location. The second timing circuit controls the period in which the lock device is released, during which time the person seeking entry may access the locked facility. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     Other advantages and features of the invention will be apparent upon consideration of the following detailed description when considered in conjunction with the drawings, wherein: 
     FIG. 1 is a schematic pictorial representation showing, in general, the relationship of a number of secured locations to which entry may be controlled from a common control station which transmits control signals through a commercial telephone central office, and 
     FIG. 2 depicts the manner of assembling the schematic circuit diagrams shown in FIGS. 3 and 4 to portray a system by which a controller may selectively control access to a number of remotely located locked premises in accordance with the principles of the present invention. 
    
    
     DETAILED DESCRIPTION 
     The terms dial and dialing as used in the specification refer or relate to the depression of pushbutton or other call signals generating means associated with a telephone station set to generate multifrequency signals or dial pulses comprised of various combinations of several fundamental frequencies, e.g., the standard commercial code combination of two or four low frequencies and/or three higher frequencies. 
     Referring to FIG. 1, there is pictorially illustrated a pair of remote secured buildings 21 and 22 having access doors 23 and 24 which are respectively maintained in a locked condition by solenoid controlled locking devices 26 and 27. The selective release of the locking devices is under the control of a security guard or controller located at a common control building or station 28. The communication and control channels for the locking devices 26 and 27 are established through the use of the standard commercial switched telephone network, a telephone company central office of which is represented by the reference numeral 29. 
     In general, a person seeking access to one of the secured buildings picks up a receiver 31 of a conventional repertoire dialer telephone set 32. The automatic dialing unit of the telephone set is effective to generate a standard multifrequency series of seven or more dial pulses indicative of the call number of a controller&#39;s telephone set 33 located in the building 28. It will be noted that the telephone sets at the remote secured locations need not have pushbuttons or other manually operated dials. Further, it is contemplated that each automatic dialing equipment is secured within the associated locked building. Upon ringing of the controller&#39;s telephone set 33, the controller picks up the receiver and orally verifies the identity of the caller seeking access to the secured building. Upon recognition of the authority of the caller to access the building, the controller presses a special or asterisk button 34 to generate a first multifrequency tone dial signal which is impressed through the central office to condition control circuitry at all of the locked facilities. Next, the controller depresses two number pushbuttons indicative of one of the remote secured buildings which signals are routed through the central office to operate the conditioned control circuitry to release the locking device for a limited period of time. If the caller does not open the locked entry door in the limited time period, the lock device is again locked and the entry procedure must be repeated to gain access to the secured building. 
     The controls for one of the lock devices are shown in FIGS. 3 and 4 where one telephone set 32 is depicted as being connected through tip and ring wires 38 and 39 to the telephone central office 29. The person seeking entry to the locked facility lifts the receiver of the set 32 and establishes the communication channel to the controller, and upon verification of the identity of the caller, the controller depresses an asterisk button on the telephone set 33 to generate a two frequency tone signal that is impressed through the central office and over the tip and ring wires to a pair of bypass wires 42 and 43. The asterisk multifrequency signal is impressed on a decoder 44 which is of standard manufacture and is adapted to convert two frequency telephone tone signals into binary coded digital signals which appear as binary logic 1 or 0 conditions on a group of four output wires 46. The standard binary coded representation for asterisk signal is 1011. The logic 0 condition is inverted by inverter 47 to logic 1 and is impressed along with the other three logic 1 conditions to a pair of gates 48 and 49 which react to apply two logic 1 pulses to a gate 51. Gate 51 produces a logic 1 output that is applied to a one-shot multivibrator 52 having a period of operation set by a resistor 53-capacitor 54 network. During the period of operation of the multivibrator 52 which is set to time out within a predetermined time, e.g., five seconds, the controller must transmit the necessary succession of two call numbers peculiar to the locking device 26 at the calling location 21. 
     A Q output of the multivibrator 52 goes from a normal reset logic 1 to a logic 0 so as to impress negative potential over a lead 61 to operate a light emitting diode 62 which, in turn, operates a phototransistor 63. Operation of this transistor 63 is accompanied by simultaneous operation of transistor 64 to control the application of energizing current to a relay 66. Energized relay 66 opens a pair of contacts 67 and 68 connected in the tip and ring lines 38 and 39 to disconnect the telephone 32 from the communication circuit. This action serves to preclude the entry seeking person from hearing or detecting any subsequent coded signals which are utilized to release the locking device 26. The operation of relay 66 is also effective to close a contact 69 which functions to connect a resistor 71 across the bypassed tip and ring wires 42 and 43 and, thus in effect, places an impedance across these lines approximating the impedance of the disconnected telephone 32. 
     When one-shot multivibrator 52 operates, a Q output thereof goes from logic 0 to logic 1 which is impressed on a line 73 running to a clear input of a negative-edge-triggered J-K flip-flop 74 forming a first stage of a two stage stepping circuit to enable this flip-flop for subsequent operation in response to a negative going or trailing edge of a clock pulse impressed on a ready line 76. Each time a multifrequency signal is applied to and transformed to a binary coded digital signal by the converter 44, the converter recognizes the presence of the impressed signal and generates a positive going logic 1 ready pulse which is impressed on the line 76. This ready pulse is maintained on the line for the period that the controller depresses a dial pushbutton on the telephone set 33. 
     The logic 1 output Q from the one-shot multivibrator 52 is also impressed over line 77 and 78 to the clear or reset ports of a pair of negative-edge-triggered master slave J-K flip-flops 81 and 82 forming two stages of a sequence circuit to enable these devices to respond to sequential inputs applied to the respective J ports. These sequence flip-flops 81 and 82 are initially biased to a reset condition so that the Q outputs are at logic 0. The flip-flops 81 and 82 are subsequently operated in sequence in response to the proper receipt of the two call number sequence dialed by the controller which is the call number indicative of the building 21. 
     Upon termination of the asterisk signal, the logic 1 condition on line 76 goes to logic 0, and this transition is effective to trip the flip-flop 74 to drive the Q output thereof to logic 1. This logic 1 condition is impressed through and delayed by a pair of tandem connected inverters 83 and 84 to produce a delayed logic 1 condition that is impressed on a clear input of a negative-edge-triggered J-K flip-flop 86 forming the second stage of the stepping circuit. Flip-flop 86 is initially set with a normal Q output at logic 0 and a complementary Q output at logic 1. The receipt of the logic 1 at the clear input of flip-flop 82 enable the flip-flop to respond to the negative transition of the next logic 1 pulse on the line 76. This next pulse transition occurs upon conclusion of the dialing of the first number of the two number sequence needed to release the locking device 26. 
     The receipt of the first number signal of the required two number lock releasing sequence in the converter 44 results in the impression of binary coded digital signals on the leads 46 that are impressed on leads 87 running to multiplexer 88 of the conventional type. The multiplexer 88 is associated with a series of ten switches 89-1-0 which may be selectively closed to respond to a particular binary coded signal input to produce an output at a selected, designated output port 91. Assume that the first of the two number sequence is the number 2, then the closure of the switch 89-2 will result in a change in the logic state of the output 91. Initially output 91 is set at logic 0 so that the selection of the output 91 causes the logic output to go to logic 1. The logic output is impressed on line 92 to the J input of the conditioned flip-flop 81. 
     At the time during the receipt of the first number, e.g., 2, the flip-flop 86 is in a reset condition and the Q output is at logic 1 which is impressed as an enabling condition to a first input of an AND gate 93. During the presence of the first dial number, there is a logic 1 condition impressed on the ready line 76 so that a logic 1 condition appears on the second input to the enabled AND gate 93. The output of gate 93 is, thus, at logic 1 and, a logic 1 condition is impressed over line 94 running to the clock input of the flip-flop 81. At the termination of the ready pulse on line 76, the gate 93 is cut off so that the negative going transition of the pulse acts as a transfer signal and is effectively impressed from gate 93 to toggle flip-flop 81 thereby transferring the logic 1 condition of the J input to the Q output. The flip-flop 81 acts as a latching device and will stay in this latched state until there is a transition of a logic 1 to a logic 0 condition impressed on the clear input. This resetting transition will not occur until the one-shot multivibrator 52 times out and resets which occurs at the expiration of the normal time period afforded the controller to dial the two number sequence needed to open the lock device 26. 
     The logic 1 output of flip-flop 81 impressed over a line 96 to a first input of an AND gate 97 having a second input connected through line 98 to the Q output of the second sequence flip-flop 82. The flip-flop 82 only operates in response to the proper receipt of the second number of the two number sequence for the building 21. In response to the release of the dial pushbutton on the controller telephone set 33, the ready pulse on line 76 goes from logic 1 to logic 0 and thus the negative-edge-triggered flip-flop 86 changes states and the Q output goes to logic 1. This change is impressed as a logic 1 on an &#34;AND&#34; gate 101 to enable this gate for subsequent operation upon application the next logic 1 pulse on the ready line 76. 
     The receipt of the next or second number multifrequency signal of the two number sequence in the converter 44 results in the application of a binary coded signal being impressed over leads 46, 87 and a set of leads 103 running to a second multiplexer 104 having a response setting group of contacts 105-1 to 105-0. A contact 105-1 to 105-0 is selected so that the multiplexer responds to the second designated number of the dial sequence to produce a change in the state at an output 106. Assume that the second number of the required sequence is the number 4 then the contact 105-4 is closed so that there is a change in the state of the output 106 upon receipt of this second number. Output 106 is normally at logic 0 but upon selection goes to logic 1 to impress a logic 1 condition over a line 107 running to the J input of the now enabled flip-flop 82. 
     When the second number signal is converted, there is a third logic 1 pulse placed on the ready line 76. Upon termination of the dial pulse indicative of the second number, the logic condition on ready line 76 goes from logic 1 to logic 0. There is a consequent change in the logic output of the now operated AND gate 101. This transition from logic 1 to logic 0 is impressed as a transfer signal over a line 108 to the clock input of a flip-flop 82 which responds by toggling and transferring the logic 1 J input to the Q output. The appearance of logic 1 on the Q output of flip-flop 82 causes a logic 1 condition to be impressed on the line 98 to operate gate 97 that functions to impress a logic 1 condition on a one-shot multivibrator 111. The period of operation of multivibrator 111 is set by a resistance 112-capacitance 113 network and values are selected for these elements to hold the multivibrator in a flipped state for a sufficient period of time to permit the person at building 21 to enter the locked door. 
     When the one-shot multivibrator 111 is tripped to a set state, its Q output goes from logic 1 to logic 0 thereby permitting current to flow through a light emitting diode 114. Light from the diode 114 operates a phototransistor 116 and simultaneously therewith a transistor 117 is operated to supply energizing current to a relay 118. Operation of this relay controls the application of current to the solenoid operated locking device 26. The locking device 26 is now released for a period of time as determined by the selection of the components controlling the period of operation of the one-shot multivibrator 111. If the person does not enter within the period of operation of the multivibrator 111, the multivibrator reverts to the initial setting and the diode 114 is de-energized to release the relay 118 and, thus, the locking device is reactivated.