US 3671721 A
A data reading system for use particularly in cash- or goods-dispensing machines in which the data to be read is represented by a plurality of passive resonant devices in or on a card and in which, when said data is to be read from said card, said card is placed in the field of a reactive element fed with variable frequency oscillations and associated with counting means in such a way that the count registered by said counting means indicates the resonant frequency of any one or more of said resonant devices located in said field.
Claims available in
Description (OCR text may contain errors)
United States Patent Hunn et al. 1 June 20, 1972  DATA READING SYSTEMS 3,328,564 6/1967 Stuart et a1 .235/92 TF  Inventors: Bernard Albert Hunn, Berkhamsted; 2 Elsa Neville Hatfield both 3:493:954 2/1970 Bartlett et al. ....340/258 c gland 3,531,627 9/1970 Ham 1 ..235/6l 12  Assignee: Revenue Systems Limited, Luton,
Bedfordshire, England OTHER PUBLICATIONS Hausman and Slack, Physics," August, 1948, pages 447,  Filed. Dec. 12, 1969 448 and 475 477- I  Appl. No.: 884,601 Barber, 21 Ways to Pick Data Off Moving Objects," Control Engineering, January, 1964, pgs. 6 l 63.
 Foreign Application Priority Data Primary ExaminerMaynard R. Wilbur Dec. 12, 1968 Great Britain ..59,162/68 Assistant E-wminerThomas Sloyan AttorneyBerman, Davidson and Herman  US. Cl. ..235/61.ll H, 235/61.12 N, 235/92 TF,
340/171, 340/185, 340/258 0 [571 ABSTRACT [5 l] Int. Cl ..G06k 7/08, 606k 19/06, 1103b 23/00 A data reading System f r use particularly in cashor goods-  Field of Search ..235/6l.l l l61.1 l7, dispensing machines i which the data to be read is 235/92 TF, 61.12; 340/149 A, 258 C, 184, 171, epresented by a plurality of passive resonant devices in or on 185; 331/178; 179/100-2 A; 194/14; 328/27 78; a card and in which, when said data is to be read from said 336/200; 338/195 card, said card is placed in the field of a reactive element fed with variable frequency oscillations and associated with 1 References Cited counting means in such a way that the count registered by said counting means indicates the resonant frequency of any one UNITED STATES PATENTS or more of said resonant devices located in said field. 2948105 1 8/ 1960 Eisler A card for use in such a system comprises a plurality of passive 2,774,060 12/1956 Thompson resonant devices, the resonant frequencies of which represent 1 7 824 12/1957 Albrlght the data carried by the card. 2,851,596 9/1958 Hilton ..235/92 3,180,321 4/1965 Aldinger ..340/171 X 17 Claims, 7 Drawing Figures PULSE GENEPATOR SHAPE? GUI/N75? RAMP OSC/ZLA TOR M S N R 0 Z p gpz y X STATIC/SEA FDR/V5? Patented June 20, 1972 4 Sheets-Sheet 2 CLOCK lNI/E/VTORS:
BER/VIQRD /-7L.BEI?T I--/UNN ELGAN NEVILLE HON/ELL Mum f 4 Sheets-Sheet 3 1 L w W a p 00 0. m M 6%. w K m a .,v Kw J J m w M .o 6 1 1 J D I a 5 BC ELGAN NEVILLE #040544,
BY M Patented June 20, 1912 3,671,721
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BERNARO ALBERT HUN/V, ELGAN NEVILLE HOWELL A rraalvs Ys.
DATA READING SYSTEMS This invention relates to data reading systems, and it is an object of the invention to provide a system for reading out data from cards. The term card" is used herein to denote any convenient form of token or the like which may be carried and inserted in a reading machine. Such cards may be used, for example, as requisitioning elements for cashor goodsdispensing machines, as fixed word stores or programs for computers, or for any other purpose for which reliable and accurate identification of the card is essential.
From one aspect, the invention consists in a data reading system in which the data to be read is represented by a plurality of passive resonant devices in or on a card and in which, when said data is to be read from said card, said card is placed in the field of a reactive element fed with variable frequency oscillations and associated with counting means in such a way that the count registered by said counting means indicates the resonant frequency of any one or more of said resonant devices located in said field.
From another aspect the invention consists in a card for use in a system according to the preceding paragraph said card comprising a plurality of passive resonant devices, the resonant frequencies of which represent the data carried by the card.
It is to be understood that, in a system in accordance with the invention, the count registered by the counting means is varied in synchronism with the frequency of the oscillations. If the frequency of the oscillations is varied continuously from a first frequency to a second frequency while the count registered by the counting means is varied in steps from a first number to a second number, each number registered by the counting means will correspond to a band of frequencies, whereas, if the frequency of the oscillations is varied in steps, each number will correspond to a particular frequency. In either case, the arrangement will be such that the presence of a resonant device in the field of the reactive element will affect the operation of the system in such a way that a signal is produced when the frequency of the oscillations is substantially equal to the resonant frequency of the resonant device. This signal may be used to stop the counting means or to transfer the number registered by the counting means when the signal appears to a store.
The oscillations may be produced by a single variable frequency oscillator, or when the frequency of the oscillations is to be varied in steps, a number of oscillators may be used, one tuned to each frequency. When a single oscillator is used, the reactive element may form part of its tuned circuit, but, since the presence of a resonant device in the field of a reactive element used in this way may affect the operating frequency of the oscillator, it may be desirable to use a buffer or power amplifier and include the reactive element in this part of the circuit. In any case, an arrangement of this kind will normally be necessary when a plurality of oscillators are used. Preferably, the outputs of all the oscillators are coupled to the input of the buffer amplifier and the oscillators are put into, and out of, action by means of switches or gates controlling the low-frequency or direct-current parts of the circuit.
The frequency of the oscillations may be increased over a relatively long period and then returned rapidly to its initial value or it may be varied first in one direction and then in the other a number of times in each cycle. Obviously the operation of the counter must have a known relationship with the variations of frequency, but the apparatus may be designed so that this relationship and/or the manner of varying the frequency is changeable at will, for example, by means of a program. Thus, the reading machine may form part of a computer and the computer itself may be programmed to produce the required variations and relationships.
The data represented by the resonant devices may be in the form of a plurality of characters of any desired kind, but it is convenient to regard each character as a digit, and to describe the data on the card as a multi-digit number. Any convenient numerical system may be used, and each digit may be represented by one or more resonant devices. All the digits on the card may be read out simultaneously if a number of reactive elements is provided equal to the number of digits in said multi-digit number. Alternatively, a single reactive element may be used and the digits may be read out sequentially, for example, by removing the card and replacing it with the resonant device or devices representing the next digit in the field of the reactive element.
When a buffer amplifier is used, it may feed a plurality of reactive elements, each arranged to read out one digit from the card. In this case a first frequency may be fed to all said elements in succession, whereinafter a second frequency is fed to all the elements in succession, and so on. Alternatively, all the frequencies may be fed in succession to one element, whereinafter all the frequencies are fed in succession to the next element, and so on. In yet another system, selective frequencies may be fed to different elements.
If the radix of the numerical system is relatively high, a relatively wide frequency range will be required if each digit is represented by a single resonant device. The maximum radix that can be used with a particular frequency range and with a single resonant device representing each digit will depend on the ability of the system to differentiate between adjacent frequencies. In many cases, therefore, it will be found more convenient to use more than one resonant device to represent each digit. For example, it is possible to use a numerical system with the radix 2" even though the system is capable of recognizing only n different frequencies, provided each digit is capable of being represented by up to n resonant devices. In this case it is convenient to use counting means having only 11 active states, each state corresponding to one of said n frequencies, and to provide, in addition, an nelement binary store, each element again corresponding to one of said n frequencies. If a device resonant at one of said frequencies is in the field of the reactive element, the store will receive a signal indicative of the count registered by the counting means (which count corresponds to the frequency of the resonant device) and the element corresponding to that frequency will be activated. In such an arrangement, if a plurality of resonant devices resonant at different frequencies are located in the field of the reactive element, a corresponding plurality of elements of the store will be activated. The resonant devices may be, for example, coils, cavities or slots.
The reactive element to be used with the oscillator, or with each oscillator, may be inductive or capacitive. If an inductive element is used, it may be in the form of an elongated loop and a plurality of resonant devices may be arranged in or on the card in such a way that all the resonant devices representing a particular digit are capable of being located within the field of the inductive loop simultaneously. In this case, the oscillator may be arranged to pass a signal to the counting means each time the frequency of the oscillator coincides with that of one of the resonant devices, so that the count registered by the counting means at that time can be transferred to the store. By way of example, it will be assumed that up to three resonant devices can be provided for each digit and that the radix of the numerical system is 8. In this case, it is only necessary for the system to differentiate between three portions of the frequen cy band and, if rest and resetting periods are ignored, the counting means need only count to 3. One possible way of deriving eight separate indications from such an arrangement is to use standard binary notation as shown in the Table I. A 1" in any particular column indicates the presence of a device on the card resonant at the frequency concerned and also means that the corresponding element in the store will be activated.
In order to accommodate a large number of digits on each card, it will frequently be desirable to locate the resonant elements relatively close together. In such circumstances, it may be difficult to design the reactive element so that only a single resonant device, or only a single group of resonant devices representing a particular digit, is located within the field of the reactive element at a particular time. Accordingly, in order to avoid the possibility that adjacent resonant devices will affect the oscillator, it is convenient to use two or more frequency bands and to arrange the resonant devices on the card in such a way that devices resonant in any particular band are separated from each other either by devices resonant in another band, or by a space if the next digit happens to be a zero. If, in accordance with Table I, frequencies f to f are used to represent the digits to 7 in one position in the number stored on the card, frequencies f, to f, may be used to represent the same digits in adjacent positions in the number. If necessary, of course, more than two frequency bands may be used to ensure sufficient separation between two devices resonant in the same band.
The resonant devices may take any convenient form having regard to the space available and the frequency range of the oscillator. In one particular system, each resonant device is in the form of a fiat metallic spiral located on an insulating surface. Such spirals may be produced, for example, by printed circuit techniques. In this case, it is also convenient for the reactive element of the oscillator to be an inductive loop or the like. When each digit may be represented by a plurality of spirals, it is desirable that the loop should be of elongated form so that all the spirals representing a particular digit may be arranged in line.
Methods of performing the invention will now be described with reference to the accompanying diagrammatic drawings, in which FIGS. 11 and 2 illustrate alternative forms of data carrying card in accordance with the invention;
FIG. 3 is a block diagram of a system in accordance with the invention;
FIG. 4 illustrates wave forms occurring in one particular embodiment of the system illustrated in FIG. 3; and
FIGS. 5, 6 and 7 are circuit diagrams of parts of the system illustrated in FIG. 3.
FIG. 1 of the drawings shows a card for use in a system in accordance with the invention, and it will be seen that the card is divided into six columns and three rows. Each column represents a digit in a radix-8 numerical system, and each column may be blank or may include one, two or three coils. The card includes a base of insulating material and metallic coils are produced on the base by a photo-etching technique. Any coils in the first, third and fifth columns starting from the left of the card in FIG. 1 may be resonant at any one of three frequencies fl, 12 or J3 and any coil in the second, fourth and sixth columns of the card may be resonant at any one of three frequencies f4, f and f6. If the standard binary notation set out in Table I is used, the digits represented by the various groups of coils in the six columns will be as shown in FIG. I at the foot of each column.
A card of the kind illustrated in FIG. 1 may be produced, for example, by means of a special mask depicting coils of the required frequencies. Alternatively, all the coils may initially be given the same resonant frequency, and the data may be entered on the card by removing parts or all of some of the coils so that the required frequency distribution is produced. Another method of producing a card for a system in accordance with the invention is illustrated in FIG. 2, from which it will be seen that the coils resonant at the particular frequencies are always located in the same rows on the card. Thus, a card of this kind may be produced by initially forming coils in all the possible eighteen positions on the card and by thereafter removing certain of the coils, for example, by grinding, in order to form the digits required. The possible combinations that can be obtained in this way are the same as in a card of the kind illustrated in FIG. ll, but it is clear that forgery would be somewhat easier.
Either of the cards illustrated in FIG. 1 or FIG. 2 may be read either column by column or as a whole. In the first instance, a first inductive loop may be used to read out the digits. in the first, third and fifth columns, and a second inductive loop may be used to read out the digits in the second, fourth and sixth columns. For parallel reading, on the other hand, six loops must be used, each with its own oscillator. The loops used for the first, third and fifth columns must be connected to oscillators whose frequencies are variable between fl and f3 and the loops used for the second, fourth and sixth columns must be connected to oscillators whose frequencies are variable between f4 and f6.
FIG. 3 of the drawings shows the apparatus required for reading out one character from a card in a system in accordance with the invention. In a complete system, the apparatus illustrated could be repeated a sufficient number of times to read out all the characters on the card.
The apparatus illustrated in FIG. 3 includes a pulse generator M in the form of a muIti-vibrator and the output of this pulse generator is applied to a shaping circuit S to provide a rectangular waveform as shown in the top line of FIG. 3. This waveform is applied to the input of a counter N which has a plurality of outputs which are applied to a decoder V. The number of stages in the counter will depend on the radix of the numerical system used on the card, and the present embodiment will be described with reference to a system in which the radix is 8, and the number of stages in the counter is three. If a decimal system is used, the counter would have more stages.
One output of the counter N shown in line D of FIG. 4, is applied to the control input of a ramp generator R as well as being applied to the decoder V. It will be seen from FIG. 4 that the waveform on this output includes a negative-going edge at It) and a positive-going edge at t3. The negative-going edge is used to start the ramp generator, and the positive-going edge is used to return the output of the generator to zero. An idealized form of the output is shown at R in FIG. 4.
The output of the ramp generator R is applied to an oscillator O and serves to vary the frequency of the oscillator in accordance with the magnitude of the waveform. Thus, the frequency of the oscillator can be represented by a graph of the same form as the ramp generator output R. The oscillator includes a search element in the form of an elongated loop 0 which forms part of the oscillatory circuit. When a card is being read, the resonant device or devices representing the digit to be read is, or are, located in the induction field of the search element Q. Accordingly, when the operating frequency of the oscillator is approximately the same as the resonant frequency of the, or each, resonant device, the resonant device changes the load on the oscillator. The reflected load alters the operating conditions of the oscillator and produces a change in the potential of a line Y leading to a threshold detector T. This detector is set so that it produces an output signal on a line Z when the reflected load on the oscillator exceeds a predetermined value. The output signal on the line Z is buffered by a driving circuit P so that it energizes its output U, which leads to a staticizer W. The outputs of the decoder V are also supplied to the staticizer W, and the output of the staticizer is applied to a display unit X. The arrangement is such that the staticizer activates one of three 2-state display members such as lamps L1, L2, L3 in the display unit when a signal appears on the line U, the display member energized being determined by the signals on the output lines of the decoder V at the time of occurrence of the signal on the line U.
From the above, it will be seen that the display member or members that is, or are, energized will depend on the count registered by the counter N at the time when the frequency of the oscillator corresponds to the frequency of the resonant device or devices on the card. Thus, the arrangement described serves to read out the digit represented by the resonant device on the card. If there is only one resonant device on the card, only one display member will be energized, but if there are two or more devices resonant within the frequency range of the oscillator and located within the field of the search element 0, two or more of the display members will be energized. Thus, there are 2 possible combinations and, it is therefore possible to store and read out digits of a radix-8 numerical system by using up to three resonant elements on the card, and with a display unit having only three 2-state display members. The actual digits represented by the various combinations of energized display units may, of course, be chosen in accordance with any desired code.
The multi-vibrator M and the shaping circuit S can take any conventional form, as can all the other parts of the apparatus. However, one particular form of counter N will now be described with reference to FIG. 5 of the drawings.
As already mentioned, the system being described is intended to read out digits having a radix equal to 8, and the counter illustrated in FIG. 3 is designed to operate in such a system. However, to allow for a re-set period between readout periods, a modulo-5 counter is used. The counter is designed to step on the negative-going edges of the pulses from the shaping circuit S and these edges are designated as 10 to :4 in the top line of FIG. 2. The counter includes three trigger units such, for example, as J-K flip-flops 11, 12 and 13, each having a clock input, two triggering inputs, two set inputs, and two complementary outputs. One triggering input of each trigger unit is designated by the letter J and another triggering input of each unit is designated by the letter K. In a J-K flip-flop each of these inputs would be in the form of an AND gate having three inputs and accordingly, it is to be understood that the three inputs are connected in parallel in each case. One output of each trigger unit is designated as 6 (pin 10) and the other output as Q (pin 5). In addition, the output 10 of unit 11 is designated as B while the output 5 is designated as B. Similarly, the outputs 10 and 5 of the units 12 and 13, are respectively, C and if and D and D. The set inputs of the units 11, 12 and 13 are not used in the counting function and, accordingly, are energized in such a way that the operation of each unit depends on the potentials applied to the other input terminals. The output of the shaping circuit S, which appears on the line 14, is applied to the clock inputs of all the flip-flop units, and the arrangement is such that there is a change in the state of the counter at each of the times t to :4.
Each of the outputs 10 and of each of the trigger units is capable of assuming the value 0 or 1, the output always being on 0 if the output 5 is on 1 and vice versa. Each unit is designed to remain in its existing state until a negative-going pulse is received at its clock input. When such a pulse is received, a change of state may, or may not, occur, depending on the existing state of the unit and on the signals applied at the time to the inputs J and K. The manner in which the signals applied to the inputs .1 and K affect the changes of state when a clock pulse is applied is summarized in the following Table II TABLE III 2 B C D O 0 0 O 1 l 0 0 2 1 l 0 3 0 l l 4 O 0 l The signals on the lines B, C and D are shown in FIG. 4 under these headings and it is, of course, to be understood that the values of B, C and D are always the complement of B, C and D, respectively.
The various outputs of the counter are applied to three NAND gates 15, 16 and 17 in the decoder V. The outputs of the three NAND gates are inverted in NOT gates 18, 19 and 20 and are applied, respectively, to the inputs J of a further set of three trigger units 21, 22 and 23. These units are similar to the trigger units 11, 12 and 13 and operate in accordance with the same table except that in this case one of the set inputs is used to affect the operation. The clock input of each of these units is connected to the line U which leads to the output of the driver P. Only the output 10 of each trigger unit is used and these are connected, respectively, by lines E, F and G to conventional transistor power amplifiers controlling the lamps L1, L2 and L3. The set input that is used in each case is represented by a terminal 6 and the terminals 6 of the units 21 and 22 are connected through a NOT gate 24 to the output D of the counter, while the terminal 6 of the unit 23 is connected to the output C of the counter. If the terminal 6 of a unit is on 1, the unit will operate in accordance with Table II, but if the terminal 6 is changed to 0, the output 10 will immediately change to 0 and will be maintained on 0 so long as terminal 6 is on 0.
From the above, it will be seen that if a pulse occurs on the line U between :0 and t1, both inputs of the NAND gate 15 will be at 1, so that the input I of the unit 21 will also be at 1. The input K of this unit, on the other hand, will be at 0 and the control terminal 6 will be at 1. Thus, the line B will be at 1 and, accordingly, the lamp Ll will be illuminated. So far as the unit 22 is concerned, the B input of the NAND gate 16 will be at 0 so that the input J will also be at 0. The input K, on the other hand, is at l and accordingly, the line F will be at 0. Similarly, it can be shown that the line G will be at 0. The complete operation of the decoder and staticizer can be seen from the following Table IV Thus, it will be seen that, when the signals on the inputs J and K are both 0 or 1, the state of the output after receipt of a clock pulse will depend on its state before receipt of that The designation of any output as 0 or 1" indicates that the respective units remain in the same state as they were in before receipt of a pulse on the line U. However, it will be seen that each unit will be reset with its output 10 on during each cycle of the counter. Units 21 and 22 are reset at t3 and unit 23 is reset at t4. So long as the card remains in position with the resonant device or devices in the induction field of the search element, the units will continue to be set each cycle in accordance with Table IV, but it will be understood that, when the card is removed so that no further pulses are received on the line U, the lamps will be extinguished when the respective units have been reset.
It will be seen from FIG. 4 that the frequency of the oscillation changes from f to f during the period t to 2,, from f to f during t, to t and from f to f during to t;, If the frequency band f to f is designated as f,, the band f to f as f and the band f to f as f;,, it will be seen that lamp L1 represents the frequency f,, lamp L2 the frequency f and lamp L3 the frequency f Accordingly, if the coding system shown in Table l is used for the frequencies of the resonant devices, the information may be read off the card by applying this table to the lamps that are illuminated.
The signals appearing on the lines U, E, F and G are shown under these designations in FIG. 4 on the assumption that there are three resonant devices in the field of the loop Q, one of said resonant devices being resonant within the band f to f,, one within the band f to f and one within the band f, to f;,. Thus, there will be pulses within the corresponding time periods on the line U and the lamps L1, L2 and L3 will be lit at the times indicated by the waveforms E, F and G, thus indicating the digit 7.
FIG. 6 of the drawings shows one possible arrangement of the ramp generator R on the left-hand side of the drawing, and one possible arrangement of the oscillator 0, together with its loop Q, on the right-hand side of the drawing.
The output D from the counter N is applied through a capacitor C1 to the base electrode of a normally conducting transistor T1. A capacitor C2 is charged through the forwardly biassed collector-base junction of a transistor T2 and the conducting transistor T1. When the negative-going edge of the waveform D at t0 is applied to the base of the transistor T1, this transistor is cut off and the capacitor C2 discharges through a resistor R1 and a variable resistor R2. Since the base electrode of the transistor T2 is maintained at a constant potential, a substantially constant current discharge of the capacitor would result if the variable resistor R2 were connected directly to the lower terminal of the capacitor C2. However, since a variable capacitance diode D1 is used in the oscillator to control its frequency, and since a linear variation of frequency with time is required, it is necessary to apply an exponential waveform to the diode. Accordingly, an amplifying and shaping circuit is provided in the ramp generator to produce the required exponential waveform. This circuit includes two transistors T3 and T4, diodes D2 and D3, a potentiometer P1 and a Zener diode Z1. To produce the required characteristic, an alternating current signal is applied to the anode of the Zener diode through a diode D4 and a resistor R3. The exponential waveform is taken from the collector of the transistor T4 and is applied to the variable capacitance diode D1 through a resistor Rd.
The oscillator 0 includes a transistor T connected in a C01- pitts circuit with the frequency-determining elements including the inductive loop 0 and the variable capacitance diode D1. As already stated, the voltage applied by the ramp generator to the variable capacitance diode has a substantially exponential waveform and, accordingly, the frequency of the oscillator varies in accordance with a substantially linear waveform.
When the waveform D changes in the positive direction at t3, the transistor T1 is rendered conductive so that the lower terminal of the capacitor C2 is returned substantially to earth potential. Thus, the frequency of the oscillator O varies substantially in accordance with the waveform shown at R in FIG. 1.
If a device resonant at the instantaneous frequency of the oscillator is placed in the inductive field of the loop Q, it will absorb energy from the loop and, as a result, the operating conditions of the oscillator will be altered so that the base potential of the transistor T5 will become more positive. This change of potential appears on the terminal Y and is applied to the similarly designated terminal at the input of the circuit arrangement illustrated in FIG 7.
The arrangement illustrated in FIG. 7 includes a transistor T6 operating as a buffer, a pair of transistors T7 and T8 operating as a threshold detector, a transistor T9 operating as a further buffer, a pair of transistors T10 and T11 connected in a Schmitt trigger circuit and a pair of transistors T12 and T13, acting as a driver. It will be seen that, when the terminal Y becomes more positive as a result of the coincidence of the frequency of the oscillator with that of a resonant device in the inductive field of the loop, the emitter of the transistor T6 will also become more positive and a positive-going pulse will be applied to the base electrode of the transistor T7 through a capacitor C3. The base electrode of the transistor T8 is connected to the slider of a potentiometer P2 and this potentiometer is set so that the transistor T8 is normally conducting. The transistors T7 and T8 share a common emitter resistor R5 and, accordingly, if the amplitude of the positive-going pulse applied to the base electrode of the transistor T7 exceeds the voltage on the slider of the potentiometer P2, this transistor T7 will rob collector current from the transistor T8 so that the potential of the collector electrode of the transistor T8 becomes more positive. This increase of potential is applied to the base electrode of the transistor T9 which is connected as an emitter follower and, accordingly, a positive-going pulse is applied to the base electrode of the transistor T10 through a capacitor C4. The transistors T10 and T11 are arranged so that the transistor T11 is normally conducting and the arrival of a positive-going pulse on the base electrode of the transistor T10 will change the state of the trigger so that the transistor T10 becomes conducting in place of the transistor T11. Thus, the collector of the transistor T11 becomes more positive and a positive-going pulse is applied to the base electrode of the transistor T12 through a coupling capacitor C5. This pulse is amplified by transistors T12 and T13, arranged so that the output pulse is again positive-going. This output is converted to a negative-going pulse by an inverter 30 which feeds the line U already referred to in connection with the description of FIG. 5.
What we claim as our invention and desire to secure by Letters Patent of the United States is:
1. A data storage and read-out system, comprising:
a. means for storing data on a record member including one or more passive resonant devices each having a predetermined resonant frequency;
b. timing means for generating timing pulses at predetermined intervals;
c. counting means for generating output pulses representative of successively higher numeric states in response to each successive timing pulse;
d. means responsive to a preselected one of said output pulses for generating a succession of frequencies in predetermined relationship to the generation of said output pulses;
e. detecting means for generating a data pulse in response to the presence of one of said passive resonant devices having a resonant frequency corresponding to the instantaneous frequency of said means for generating a succession of frequencies; and
f. indicating means for indicating the numeric state of said counting means at the instant when said data pulse is generated.
2. A data storage and read-out system as set forth in claim 1, wherein said means responsive to a preselected one of said output pulses comprises oscillator means and means for continuously varying the frequency of said oscillator means from a first frequency to a second frequency while the numeric state of said counting means changes from a first number to a higher number.
3. A data storage and read-out system as set forth in claim 1, wherein said means responsive to a preselected one of said output pulses comprises oscillator means and means for varying the frequency of said oscillator means in discrete steps corresponding to each successive higher numeric state of said counting means.
4. A data storage and read-out system as claimed in claim 1, wherein said means responsive to a preselected one of said output pulses comprises a single variable frequency oscillator for producing variable frequency oscillations.
5. A data storage and read-out system as set forth in claim 3, wherein-said oscillator means comprises a plurality of single frequency oscillators and means for activating and de-activating said single frequency oscillators, one at a time.
6. A data storage and read-out system as set forth in claim 1, wherein said passive resonant devices comprise electrical conductors formed as open-ended multi-turn spirals.
7. The data storage and read-out system set forth in claim 6, wherein said multi-turn spirals are arranged in a predetermined pattern on said record member.
8. The data storage and read-out system set forth in claim 1, further including reactance means coupled to said means for generating a succession of frequencies, said record member being located in the field of said reactance means during data read-out.
9. A data storage and read-out system as set forth in claim 8, further including a buffer amplifier and wherein said means for generating a succession of frequencies is coupled to the input of said buffer amplifier, said reactance means forming part of said buffer amplifier circuit.
10. A data storage and read-out system as set forth in claim 8, wherein said reactance means is an inductive loop and said means for generating a succession of frequencies comprises oscillator means.
11. A data storage and read-out system as set forth in claim 10, wherein said inductive loop is fed with electrical energy from said oscillator means, so that when the frequency of said oscillator means is substantially equal to the resonant frequency of one of said passive resonant devices, the reflected load in said oscillator means causes said detecting means to produce a data pulse.
12. A data storage and read-out system as set forth in claim 11, further including threshold detector means for producing an output signal when the reflected load in said oscillator means exceeds a predetermined value.
13. The data storage and read-out system set forth in claim 12, further including storage means and wherein said output signal causes the numeric state of said counting means to be transferred to said storage means when the reflected load exceeds said predetermined value.
14. The data storage and read-out system as set forth in claim 8, wherein said reactance means comprises a plurality of inductive loops and the passive resonant devices are arranged on said record member so that the record member can be placed with one passive resonant device in the field of each inductive loop.
15. The data storage and read-out system as set forth in claim 8, wherein said reactance means comprises an inductive loop and the passive resonant devices are arranged on said record member so that the record member can be placed with a plurality of passive resonant devices in the field of said inductive loop.
16. A data storage and read-out system as set forth in claim 8, wherein said reactance means comprises first and second inductive loops, a first succession of frequencies being fed to said first inductive loop and a second and different succession of frequencies being fed to said second inductive loop, said passive resonant devices being arranged on said record member so that a passive resonant device having a resonant frequency in said first succession may be placed in the field of said first inductance loop and a passive resonant device having a resonant frequency in said second succession may be simultaneously placed in the field of said second inductance loop.
17. A data reading system comprising a search element, a
data-carrying card locatable in the field of said search element and comprising a plurality of passive resonant devices, the resonant frequencies of which represent the data carried by the card, means for producing a square wave, a counter driven by said means, a ramp generator controlled by said counter and itself controlling the frequency of an oscillator, the oscillatory circuit of which is in part controlled by said search element, a threshold device controlled by said oscillator and operative to produce an output signal when any one of said resonant devices resonant at the instantaneous frequency of the oscillator is located in the field of said search element, a driving circuit operative to pass said signal to a staticizer controlling a plurality of display members and a decoder controlled by said counter and itself controlling said staticizer so that the resonant frequency of said resonant device determines the display members activated by said staticizer.
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