Electronic Sensing And Actuator System

Abstract

An electronic sensing and actuator control system for sensing an energy change dependant on the proximity of a coded member to a sensor mechanism, the mechanism including an electric field producing means operative over a range of continuously varying frequencies; the coded member including a passive energy absorbing circuit responsive to a predetermined frequency range and adapted for placement in proximity to said mechanism to create a variation in the energy level of said electric field producing means; detecting means for detecting variations in the energy level of said electric field; and control-actuator means adapted to respond to the detecting means.

Description

BACKGROUND OF THE INVENTION

The present invention relates to apparatus for electrically sensing the proximity of an object and remotely controlling the actuation of an actuator responsive to the proximity of said object.

Electronic sensing and actuator control systems have various applications. There are applications in the processing or manufacturing of items in which items need be processed such as sorted, counted or tested. Other applications may include locking systems to secure designated areas from access by unauthorized persons or objects.

A lock system generally requires a portable code device, e.g., key to be utilized to actuate a locking to permit access to the secured area. The lock and key are programmed such that actuation of the lock is dependent upon coincidence between the program of the lock and the program of the key. In an electronic locking system the key program controls the actuation of an electrical circuit which, in turn controls actuation of the lock. Commonly, in electronic locking systems, in order to actuate the lock, the "key" is in the form of a card which need be inserted in a slot or socket or make other physical connection.

In various installations it is desirable to have locking systems which may be controlled by various different programs. For example, a "master key" is commonly desirable in order to entitle different authorized persons access to the secured area but at the same time it is necessary that the "master key" have a different code than other authorized "keys." Further, it is commonly desirable to have the locking system non-conspicuous and hidden from view. It is further commonly desirable to incorporate a locking system which does not require alteration of the area to create a key receiving station such as a slot, socket, etc.

The present invention teaches an improved electronic sensing and actuator control system which operates by proximity of the coded member to the sensor. When applied as an electronic lock the present invention does not require the aid of slots, sockets or physical connection for receiving the "key." It further teaches an actuator which may be adapted to respond to a plurality of coded programs.

SUMMARY OF THE PRESENT INVENTION

The present invention teaches an electronic sensing and actuator control system responsive to the proximity of an object to be sensed. The object to be sensed need not necessarily make physical contact with any other part of the apparatus but need only be brought into a sensing zone including the electrical field generated by an electrical part of the apparatus. The electrical part of the apparatus is adapted to sense the proximity and the coded program of the object and to generate a responsive control signal to an actuator mechanism in turn adapted to perform a designated function. As a locking system, the object to be sensed may be referred to as the "key." The "key" may consist of a card composed of interconnected passive electronic components, e.g., inductors, capacitors, resistors and/or crystals, such that the key may be readily transported by an individual to and from the sensing zone. The apparatus is adapted to actuate the lock when the proper key is sensed. The apparatus may be further adapted to sense and actuate an alarm if an incorrectly programmed key is brought in the sensing zone in an attempt to actuate the lock.

In an exemplary embodiment of a locking system, the key is in the form of a portable card comprised of passive inductance-capacitance elements establishing at least one resonant frequency. The electrical part of the apparatus includes a variable frequency oscillator adapted to continuously oscillate at varying frequencies within a frequency range. The electrical part of the apparatus creates an electrical field within a sensing zone in which zone the key may be brought for sensing. The electrical part of the apparatus includes a sweep voltage source extending to the oscillator adapted for controlling the oscillator frequency responsive to the sweep voltage. The sweep voltage source further engages a comparator network adapted to compare the sweep voltage to select reference voltages. The select reference voltages are selected according to desired frequencies such that the comparator may compare the actual sweep voltage to the reference voltages. The comparator network is adapted to generate a first comparator signal when the actual sweep voltage coincides with a selected reference voltage.

A detector network extends to the oscillator to detect the energy level of the oscillator and to detect the presence of the load on the oscillator. The energy level of said oscillator varies with varying load and the load varies as the key is brought into the sensing zone and the oscillator frequency approaches the resonant frequency of the key. The detector in turn generates a control signal responsive to the load conditions of the oscillator.

A controller network extends to the detector and to the comparator. The controller is adapted to control the actuator mechanism responsive to the relationship of the detector control signals and the comparator control signals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an installation of an electronic sensing apparatus and control mechanism incorporating the teachings of the present invention and applied as an electronic lock system;

FIG. 2 is a functional block diagram of the electronic apparatus and control mechanism of FIG. 1;

FIG. 3 is a circuit diagram of a variable frequency oscillator of FIG. 2;

FIG. 4 is a circuit diagram of a voltage sweep generator of FIG. 2;

FIG. 5 is a circuit diagram of a comparator network of FIG. 1;

FIG. 6 is a circuit diagram of a detector network of FIG. 1;

FIG. 7 is a graphical representation of pulse-time relationships of the circuit networks of FIGS. 5 and 6;

FIG. 8 is an exploded illustration of a key of FIG. 1; and

FIG. 9 is a functional block diagram of an alternative embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates an application of an electronic sensing and actuator control system of the present invention as utilized in an electronic locking system for securing a door 10 in turn controlling access to an enclosed area 11. The electronic sensing and control system may include a sensing network referred to by the general reference character 12 and a programmed key referred to by the general reference character 13. The sensing network 12 in turn may control an electro-mechanical actuator in the form of a lock 14 responsive to the proximity and the program of the key 13. The key 13 is a passive circuit adapted to include an electrical-field sensitive circuit or circuits having a selected resonant frequency or frequencies of a value within the range of frequencies of the oscillator 12. The sensing network 12 may be placed on the reverse side of the door 10 or at some other position remote from the lock 14. If desired, the door 10 may be marked by appropriate designations such as by lines 15 to designate a sensing zone at which location the key 13 may be presented for sensing by the network 12. In operation, when a key of a selected resonant frequency is within the sensing zone 15 the lock 14 may be actuated. If the key resonant frequency does not coincide with a select resonant frequency, the lock 14 is not actuated.

As illustrated in the block diagram of FIG. 2, the network 12 may include a variable frequency oscillator 20 including an output coil 22 which coil is positioned adjacent to the sensing zone 15 on the reverse side of the door 10. The oscillator 20 is engaged to a sweep voltage source 23. The sweep voltage source 23 continuously generates the sweep voltage v.sub.f which, in turn, continuously varies the frequency of the oscillator 20. The frequency of the oscillator 20 may be a direct function of v.sub.f, e.g., one megahertz per volt. At the same time the sweep voltage source 23 extends to a comparator network, in the form of a window comparator 24 with v.sub.f continuously applied to said comparator. A second voltage Vref., representative of a desired frequency is also applied to the comparator. The value of Vref. is preselected according to at least one of the programmed frequencies of the key 13. The window comparator network 24 is adapted to continuously generate binary logic "one" and "zero" signals responsive to the comparison of the voltage v.sub.f to the preset reference voltage Vref. For example, the comparator 24 may generate a binary logic "one" when v.sub.f coincides with Vref. and a binary logic "zero" for all other values of v.sub.f. Thus, the logic "one" comparator signal indicates coincidence of the actual frequency of the oscillator 20 and the preselected frequency and logic "zero" comparator signal indicates the absence of coincidence of the actual frequency of the oscillator 20 and the preselected frequency.

The energy level of the oscillator 20 is sensed by a detector network 25. The detector 25 is adapted to receive a sense voltage designated v.sub.d from the oscillator. The voltage v.sub.d remains substantially at a steady state level in the absence of variations of the oscillator load. The oscillator load and energy level are a function of passive reactive elements in the sensing zone 15. Accordingly, the detector 25 network generates binary logic signals responsive to changes in the energy level of the oscillator 20. During the steady state energy level of the oscillator 20 the detector 25 generates a binary logic "zero" control signal. When a reactive circuit is sensed with the sensing zone and the frequency of the oscillator 20 approaches the resonant frequency of the sensed circuit, the oscillator energy level varies and the value of v.sub.d varies. The detector 25 responds to the change in v.sub.d and generates a binary logic "one" control signal.

The comparator 24 and the detector 25 extend to a controller circuit network 26. The network 26 is adapted to operate in different modes dependent on the logic signals received from the comparator 24 and the detector 25. The controller 26 includes a first logic AND gate 27 having an input line 28 from the detector 25 and an input line 30 from the output of the comparator network 24. The AND gate 27 has an output line 32 which extends to an unlock control circuit 34 to control the lock 14. The unlock control circuit 34 may extend to a solenoid actuator 36 which is also joined to a power source + V such that in a first mode the actuator 36 may be actuated.

A second logic AND gate 38 is included and having a pair of input lines 40 and 42 with the input line 40 common to the detector 25 and the input line 42 extending from the output of a logic inverter network 44. The input of the inverter 44 is common to the output of the comparator 24. The AND gate 38 has an output line 46 extending to an alarm control circuit 48.

Thus in the event the energy level of the oscillator 20 varies responsive to a key in the sensing zone 15, the sense signal v.sub.d varies from a steady state level and the detector 25 generates a logic "one" signal. The detector "one" signal is applied simultaneously to both AND gates 27 and 38. If the sensed signal v.sub.d is at the programmed desired frequency as established by Vref., the comparator network 24 simultaneously generates a logic "one" control signal which is received by the gate 27 such that the gate 27 is actuated and generates a logic "one" on the line 32 to the unlock control circuit 34 and to the actuator solenoid 36 to activate the lock actuator. In the event that the sensed signal v.sub.d is at a frequency within the oscillator frequency range but at a frequency other than the desired frequency, the detector 25 generates a logic "one" signal. However, the comparator network 24 simultaneously generates a logic "zero" control signal. The logic "one" and "zero" signals are received by the gate 27 but the gate 27 is not activated. The inverter 44 receives the comparator logic "zero" and inverts it to a logic "one" on the line 42 and to the AND gate 38. The AND gate 38 also receives the logic "one" from the detector 25. Accordingly, the AND gate 38 is activated and generates a logic "one" on the line 46 to the alarm circuit 48 to actuate the alarm 50 indicating that a key having a resonant frequency other than the desired frequency has been detected.

FIG. 3 is a circuit diagram of a variable frequency oscillator 20 which may be incorporated in the acutator 12. The variable frequency oscillator 20 includes a common base transistor oscillator having an NPN transistor 51 with the collector and emitter tied across a capacitor 52. The output coil 22 which forms a part of the tank circuit for the oscillator 20 is tied in common to the collector and in common to a capacitor 54 in turn common to a voltage variable capacitance in the form of a varactor 56. The common junction of the capacitor 54 and varactor 56 is common to a choke coil 58 extending to the sweep voltage source 23 to receive the sweep voltage v.sub.f. The common junction of the capacitor 54 and coil 22 are common to the voltage source + V. The emitter of the transistor 51 is common to a resistance 60 which extends to ground. The base of the transistor 51 is common to a resistance-capacitance filter network having a capacitor 62 and a resistance 64 both common to ground. The base of the transistor 51 also extends through a resistance 66 to the voltage source + V. In operation the oscillator 20 generates a continuously varying frequency depending upon the value of the voltage v.sub.f from the sweep voltage source 23. The capacitor 52, the varactor 56 and the load coil 22 determine the frequency of oscillation. Variations in v.sub.f varies the capacitance value of the varactor 56. Accordingly, when the oscillator 20 is oscillating, an electric field exists around the output coil 22. Viewing FIG. 1 the electric field penetrates the door 10 within the sensing zone 15. The energy level of the oscillator varies as the operating frequency approaches the resonant frequency of passive reactive elements within the sensing zone 15.

FIG. 4 is a circuit diagram of a sweep voltage source network 23 adapted to generate the constantly varying sweep voltage v.sub.f and to vary the frequency of the oscillator within a desired range. The sweep voltage source 23 includes a unijunction transistor 68 having one emitter tied to ground and a second emitter tied to a first resistor 70 common to the voltage source + V. The gate of the transistor 68 is common to an output terminal 71 which is common to a resistor 72 extending to the voltage source + V and to a timing capacitor 74 extending to ground reference. Referring to FIG. 2, the output terminal 71 is common to the input of the variable frequency oscillator 20 and to the comparator network 24 to supply the varying sweep voltage v.sub.f. The resistor-capacitor of the resistance 72 and capacitance 74 are such that the capacitor 74 continuously charges from + V and discharges through unijunction transistor 68. The resistor 72 allows the timing capacitor 74 to charge until the unijunction transistor 68 fires at a predetermined voltage. When the unijunction transistor 68 fires the capacitor 74 discharges to the point that the unijunction transistor turns off allowing the capacitor to recharge. The charge and discharge action continuously repeats such that the sweep voltage v.sub.f at the terminal 71 continuously varies and repeats according to the values of the resistor 72 and capacitor 74.

Referring to FIG. 5, there is shown a comparator network 24 adapted to detect a particular value of the sweep voltage v.sub.f. As shown the reference voltage from the sweep voltage source 23 is received at an input terminal 76. The input terminal 76 is tied to a coupling capacitor 78 which in turn extends to a common junction 80 to a potentiometer 82. The potentiometer 82 is preset according to the reference voltage Vref. necessary to detect the resonant frequency of the key 13 programmed to actuate the latch 14. The junction 80 is common to a pair of resistors 83 and 84 of which the resistor 83 is tied to the negative terminal of an operational amplifier 86 and the resistor 84 is common to the negative input terminal of an operational amplifier 88. The operational amplifier 86 has an output terminal 87 tied to the anode of a diode 90 extending to the negative input terminal of the amplifier 86. Across the negative and positive input terminals of the amplifier 86 is a diode 92 with the anode tied to the negative input terminal and the cathode tied to ground reference and the positive input terminal. The operational amplifier 88 has an output terminal 93 joined to the cathode of a diode 94. The anode of the diode 94 is tied to the resistor 84 and to the negative input terminal of the amplifier 88. Across the negative input terminal and the positive input terminal of the amplifier 88 is a diode 96 with the cathode tied to the negative input terminal and the anode tied to the positive input terminal and to ground reference. The diodes 92 and 96 limit the voltage of the input of the amplifiers 96 and 88 to a predetermined safe value. The output terminal 87 of the amplifier 86 is tied to a resistor 96 extending to the negative input of the amplifier 88.

The sweep voltage v.sub.f as received at the terminal 76 is level shifted by means of the coupling capacitor 78 and the potentiometer 82 so that for operational purposes the reference level at the junction 80 is zero when the oscillator frequency of the oscillator 20 is equivalent to the resonant frequency of the programmed key 13. For illustrative purposes, a voltage-time diagram 99 is illustrated to graphically depict the sweep voltage v.sub.f as received at the input terminal 76 and to illustrate the shifted reference to a trigger level V.sub.t which coincides with Vref. Accordingly, when the voltage level at the point 80 is negative relative to the trigger level V.sub.t, the output of the operational amplifier 86 is positive and the diode 90 conducts. Conduction of the diode 90 clamps the output of the amplifier 86 slightly positive. At the same time the diode 94 is reversed biased by the negative potential at the terminal 80 and the amplifier 88 produces a full positive output at the terminal 93 as illustrated by a pulse waveform 100 illustrated on a voltage-time diagram. When the input sweep voltage v.sub.f exceeds the preset trigger value V.sub.t, the voltage at the terminal 80 assumes a relative positive value such that the output at the terminal 87 is negative and the diode 90 is reversed biased. This insures a negative voltage at the input of the amplifier 88 and the diode 94 is reversed biased such that a full positive voltage of a value V.sub.1 is present at the output terminal 93. As the value of v.sub.f crosses through the preset trigger level V.sub.t such that the relative potential at 80 is zero, as illustrated by the time period t.sub.1 -- t.sub.2, the voltage at the output terminal 93 of the amplifier 88 is also zero as illustrated by the value V.sub.O of the pulse diagram 100. Accordingly, when the sweep voltage v.sub.f is at the referenced trigger level V.sub.f, it indicates that the sweep voltage source 23 is at the value Vref. coinciding with the select resonant frequency of a key to actuate the loc actuator 14. Accordingly the comparator output voltage, as illustrated by the wave form 100, when at the V.sub.O value may be designated as a binary "one" and at all other values as a binary "zero." These logic binary signals, as previously discussed, are applied to the input of the controller network 26 and to the inputs of the AND gate 27 and to the inverter 44.

Referring to FIG. 6 there is shown therein a circuit diagram of the detector network 25 adapted to detect energy level variations in the oscillator 20 responsive to the presence of a key in the sensing zone 15. The detector 25 of FIG. 6 has an input terminal 101 common to the anode of an input diode 102 extending in common to the base of a NPN transistor 104. The base of the transistor 104 is tied in common to a resistance-capacitance filter comprising a capacitor 106 extending to ground and parallel with a resistor 108. The emitter of the transistor 104 is tied to ground reference through a resistance 110 and through a coupling capacitor 112 to the base of a NPN transistor 114. The base of the transistor 114 is also tied to a resistor 116 extending to the ground reference. The emitter of the transistor 114 is tied to ground reference and the collector is tied in common to a junction 117. The junction 117 is common to a resistance 118 and a capacitor 120. The capacitor 120 joins a junction 122 common to a resistor 124. The resistors 118 and 124 extend to the source + V. The junction 122 is also tied in common to a resistance 126 extending to an output terminal 128 in common to the anode of a diode 130. The cathode of the diode 130 is tied to the voltage source + V. The output terminal 128 is adapted to extend to the controller network 26 and the AND gates 27 and 38. In operation, the energy level change in the oscillator 20 due to the proximity of the key 13 will manifest itself as a decrease in the envelope voltage generated by the oscillator 20. The detector 25 is adapted to respond to level changes in the envelope voltage. The envelope voltage v.sub.d is detected by the diode 102 and filtered to produce a sharp decrease-increase level change in the amplitude as shown by the time diagram A in FIG. 7. The signal A appearing at the base of the transistor 104 passes through the emitter-follower stage of transistor 104 and is first differentiated by the capacitor 112 and resistor 116 as shown by the signal B in FIG. 7. The first differentiated signal B provides a signal representative of rater of change of the signal A. The signal B is then amplified and shaped by the common emitter transistor 114 and appears at terminal 117 as the signal C in FIG. 7. The signal C is then further differentiated by the capacitor 120 and resistor 124 to yield a negative going spike corresponding to the preset desired frequency along with two positive going spikes at two frequencies dependent on the quality of resonance as indicated by wave form D in FIG. 7. The positive going spikes of wave form D are clamped to the positive supply + V by the resistor 124, the resistor 126 and the diode 130 such that the output at the terminal 128 appears as signal E of FIG. 7. The desired negative going spike portion of the signal E represents the peak of the envelope signal A from the detector and the logic "one" level to be applied to the AND gates 27 and 38. For illustrative purposes the waveform 100 of FIG. 5 from the comparator 24 is reproduced in FIG. 7. It may be noted that in comparing the signal E with the signal 100 that there is time correspondence such that the AND gate 27 received a logic "one" at both input terminals and therefore actuate the unlock control circuit 34.

It may be noted that the output of the detector 25 is a function of the energy change of the oscillator 20 such that in the event of an energy change, the signal E is generated. At the same time in viewing FIG. 7 it may be noted that the comparator 24 generates a "one" pulse only at the voltage corresponding to the desired resonant frequency. For all other frequency values the comparator generates a logic "zero." The output of the comparator is tied to the inverter 44 such that for all frequencies other than the desired frequency the inverter 44 generates a logic "one" output. Accordingly, in the event that the oscillator 20 generates a signal A for frequencies other than the desired frequency a pulse similar to that of E is generated by the detector and applied to both the AND gates 26 and 38. With the coincidence of two logic "one" signals being applied to the AND gate 28 at a frequency other than the desired frequency, the AND gate 38 generates a signal to activate the alarm circuit 48 and actuate the alarm 50 while the AND gate 27 and latch 14 are not actuated. Actuation of the alarm 50 provides a signal that an "unauthorized key" is within the sensing zone.

FIG. 8 illustrates an embodiment of the key 13 in the form of an exploded card having a first face 132 and a reverse side face 134. For illustrative purposes, the diagram of FIG. 8 illustrates the faces 132 and 134 separated whereas in actual application the faces 132 and 134 are back-to-back in secured relationship. The key 13 unit of FIG. 8 includes a pair of resonant circuits A and B each of a resonant frequency. The first circuit A of the key 13 and illustrated in FIG. 2, includes a capacitor 135 and an inductor 136 tied in common to form a tank circuit. The capacitor 135 may comprise a pair of plates 137 and 138 with the plate 137 mounted on the surface 132 and the plate 138 mounted on the surface 134 separated by the card material comprised of a dielectric material 139. The inductor 136 comprises a strip 142 on the surface 132 and a strip 144 on the surface 134. The strips 142 and 144 are electrically joined in common by means of a through connection 146 extending through the card. The strip 142 is tied in common to the plate 137 and the strip 144 is tied in common to the plate 138. Accordingly, the resonant frequency of the circuit A of the key 13 is dependent on the values of the inductance 136 and capacitance 135. The circuit B of the key 13 is similar to the circuit A and carries the same reference numerals distinguished by a prime designation. The resonant frequency of the circuit B may be different from that of the circuit A. The card 13 is adapted such that the resonant circuits consist of only passive elements and may be designed of any of various sizes or shapes. The potentiometer 82 of the comparator is selected to relate to one of the resonant frequencies of the programmed key 13.

Viewing the diagram of FIG. 2, it may be noted that the present apparatus can be utilized to be actuated by cards of various resonant frequencies. For example, in the case of a master key 13 having a different frequency than that of a regular key 13, the network of FIG. 2 may be modified to include a second comparator 24 receiving the sweep voltage v.sub.f. The second comparator may be preset at a voltage level relating to the master key resonant frequency. The second comparator would extend to a third AND gate also extending to the detector. The third AND gate output would extend to the unlock control circuit to actuate the lock responsive to the master key. The third AND gate output would also extend to the alarm circuit to deactivate the alarm circuit in the event that the third AND gate has a logic "one" responsive to the master key.

FIG. 9 illustrates a functional block diagram of an alternative embodiment of the present invention referred to by the general reference character 150, to be utilized for purposes of counting or sorting objects carrying a programmed "key." For purposes of clarification, those elements of the embodiment 150 similar to the previously described elements will be referred to by the same reference numeral distinguished by a prime designation.

In the FIG. 9 application, a "key" may be in the form of the objects to be counted or sorted or the object with a key attached thereto. The objects carrying the keys 13.sup.1 will be continuously processed through the sensing zone 15.sup.1. As the key is brought into the sensing zone 15.sup.1, the energy of the variable frequency oscillator 20.sup.1 is changed and detected by the detector 25.sup.1. The output of the detector 25.sup.1 is fed to a controller network 151 having an AND gate 152. In the embodiment of FIG. 9 the variable frequency oscillator 20.sup.1 sweeps in steps through a predetermined frequency range. The stepping is realized by a digital-to-analog converter network 153 driven by a digital counter 154 which may carry the number corresponding to resonant frequency of the key 13.sup.1 to be identified in the sensing zone 15.sup.1. Once the key 13.sup.1 is identified the detector 20.sup.1 may send out signals through the AND gate 152 to control the desired action and destiny of the object attached to the key 13.sup.1. The counter 154 may be stepped by means of a clock circuit 155 which extends through the input of an AND gate 156 which, in turn, extends to the counter 154. The connection of the clock 155 and counter 154 may be disabled by means of the AND gate 156 through a control demand received at the other input of the AND gate 156. In FIG. 9 gate 156 is tied in common through a line 158 to the output of an exclusive OR logic gate 160 and to the input of the AND gate 152. The OR gate 160 is also tied in common to the counter 154. Accordingly, prior to a key 13.sup.1 coming within the sensing zone 15.sup.1, the counter 154 generates a signal which is applied to the OR gate 160 such that a signal appears on the line 158. Simultaneously the clock 155 generates a signal such that the AND gate 156 generates a signal thereby permitting the counter 154 to function. Upon a key 13.sup.1 coming within the sensing zone 15.sup.1, the detector 25.sup.1 detects the change in energy level. Accordingly, the AND gate 152 is activated thereby disabling the output of the OR gate 160 and the signal on the line 158. Accordingly, the counter is disabled until the key passes through the sensing zone 15.sup.1. The OR line 158 is also common to an output terminal 162 such that an actuator mechanism (not shown) may respond to the presence of a key 13.sup.1 in the sensing zone 15.sup.1. Once the key 13.sup.1 passes through the sensing zone 15.sup.1 the OR gate may be reset and the apparatus 150 reactivated for detecting purposes. A more specific example of the application of the embodiment 150 of FIG. 9 may be for sorting inductors, capacitors or any resonant circuit of unknown value. For example, to sort inductors, a key in the form of a capacitor of known value may be connected to the inductor of unknown value to form a resonant circuit. As the formed circuit passes the sensing zone 15.sup.1 the variable frequency oscillator 20.sup.1 will identify the resonant frequency and then control a sorting mechanism to place the inductor in a bin representing its particular value.

Claims

I claim:

1. An electronic sensing and actuator control system for controlling an actuator, the system comprising, in combination:

a variable frequency oscillator means adapted to repeatedly sweep through a range of operating frequencies and generate a field at said operating frequencies within a sensing zone, the oscillator being adapted to generate an energy level signal representative of the energy level of the output field;

a key unit means adapted to be transported to said sensing zone, the key unit comprising a field sensitive circuit having at least one selected resonant frequency, said resonant frequency being of a value within the range of frequencies of said oscillator;

an energy level detector means for receiving said energy level signal, detecting variations in the energy level of the oscillator means and generating a responsive detection output signal responsive to the energy level of the oscillator means;

a controller network adapted to be responsive to the detector output signal to generate responsive control signals for controlling an actuator mechanism; and

means for interconnecting the controller network to an actuator mechanism.

2. The system of claim 1 in which

the variable frequency oscillator means is adapted to repeatedly sweep through a range of operating frequencies and generate an electrical field at said operating frequencies within a sensing zone, the oscillator being adapted to generate an energy level signal representative of the energy level of the output field; and

the key unit means adapted to be transported to said sensing zone, the key unit comprising an electrical field sensitive circuit having at least one selected resonant frequency, said resonant frequency being of a value within the range of frequencies of said oscillator.

3. The system of claim 2 further including

a comparator network for comparing the actual frequency of the oscillator means to at least one preselect frequency, the comparator network adapted to generate a responsive comparator control signal responsive to the relationship of said actual frequency and said preselected frequency.

4. The system of claim 3 in which the controller means is adapted to respond to said detector output signal and said comparator control signal.

5. The system of claim 4 in which

the detector means is adapted to generate a first detector output signal state responsive to variations in energy level of the oscillator means and a second detector output signal state responsive to the steady state energy level of the oscillator means;

the comparator network is adapted to generate a first comparator output signal state responsive to coincidence of the actual frequency of the oscillator and said selected resonant frequency and a second comparator output signal state responsive to the absence of coincidence of the actual frequency of the oscillator and said selected frequency; and

the controller network is adapted to respond in at least two different modes, one of said modes being in response to receiving the first detector output signal state and the first comparator output signal state and another of said modes being in response to receiving the first detector output signal state and the second detector output signal state.

6. The system of claim 5 in which

the key unit means includes passive electronic components joined in a circuit of said selected resonant frequency.

7. The system of claim 6 in which

the oscillator means is in the form of a voltage frequency oscillator adapted to sweep through a range of frequencies responsive to a sweep reference voltage; and including

a sweep voltage source adapted to generate a sweep reference voltage and engaged to the oscillator means to control the frequency of the oscillator.

8. The system of claim 7 in which

the comparator network is in the form of a voltage comparator, the comparator being engaged to the sweep voltage source to receive said sweep reference voltage, the comparator network further adapted to receive at least one preset reference voltage of a fixed value, each of said preset reference voltages being adapted to be preset of a value corresponding to one of said selected resonant frequencies.

9. The system of claim 8 in which

the energy level detector means includes an input means for receiving said energy level signal and first differentiating means for differentiating said energy level signal and producing a signal representative of the rate of change of the peak amplitude of said energy level signal.

10. The system of claim 9 in which

the energy level detector means further includes a second differentiating means for differentiating the signal of said first differentiating means for producing a signal representative of the peak of said energy level signal.

11. The system of claim 10 in which

the controller network includes a logic AND gate extending to the comparator network and to the detector means and adapted to generate a control signal responsive to the time relationship of said comparator output signal state and said detector output signal state; and

an actuator mechanism adapted to respond to the control signal of said AND gate.

12. The system of claim 1 further including

a digital-to-analog converter for generating a frequency reference voltage responsive to input digital signals for controlling and converter, the counter means being responsive to a clock means extending to the counter means through a disabling means, said disabling means being adapted to disable the counter responsive to a control demand of the controller network.

13. The system of claim 12 in which

the controller network is in the form of an AND gate adapted to respond to said detector output signal and to said disabling means, an OR gate adapted to respond to said AND gate output and said counter such that the counter is disabled responsive to said detector output signal.

14. The system of claim 7 in which

the key unit means includes a plurality of electrical field sensitive circuits each having a select resonant frequency, each of said resonant frequencies being of a value within the range of frequencies of said oscillator.