US3438489A - Automatic sorting system for articles such as mailbags - Google Patents

Description

April 15, 1969 M. J. CAMBORNAC ETAL 3, 3

AUTOMATIC SQRTING SYSTEM FOR ARTICLES SUCH AS HAILBAGS Filed June 12, 1967 Sheet V of 8 PALO ALTO CALIFORNIA A410 4170 (lama/m4 ya Hg. 5a.

INVENTORS Itcltl I. mum Jean J. CHAZOT Lucien P. PUECHBgRTY nyw jaz/zz A ril 15, 1969 M.J. CAMBORNAC ETAL 3,438,489

AUTOMATIC SORTING SYSTEM FOP. ARTICLES SUCH AS MAILBAGS Z of 8 Sheet Filed June 12, 1967 FIG. 2

FIG. 6

mvwroks c a a W W m .m J P Q mmd mum April 15, 1969 M. J. cAMBoRNAc ETAL 3,438,489 AUTOMATIC SOBTING SYSTEM FOR ARTICLES SUCH AS IAILBAGS Filed June 12, 19s? Shee t J of a 1mm Michel J. CAHBORNAC Jean J. CHAZOT Lucien P. PU CHB ERTY April 15, 1969 M.J. CAMBORNAC ETAL 3,438,489

AUTOMATIC SORTING SYSTEM FOR ARTICLES SUCH AS MAILBAGS Filed June 12, 1967 Sheet 018 NVEN'ITORS:

mzchct J. Jean J. CHAZOT Lucien P. PUB ERTY MW A ril 15, 1969 M.J. CAMBORNAC ETAL 3,433,439

AUTOMATIC SORTING SYSTEM FOR ARTICLES sucn AS MAILBAGS Filed June 12, 1967 Sheet 6 of 8 Q 5 8 x u 05 C ODER INVENTORS 2 Michel J. CAMBORNAC Jean J. CHAZOT Lucien P. PUEC BY M April 1969 VM.J. CAMBORNAC ETAL 3,438,489

AUTOMATIC SORTING SYSTEM FOR ARTICLES SUCH AS MAILBAGS Filed June 12, 1967 Sheet 7 of 8 a: 5 I 4 -44- 6.41 o 90 INVENTORS:

Michel J. cmsoamc Jean J. CHAZOT Lucien P. PUEC ERT! AUTOMATIC SORTING SYSTEM FOR ARTICLES SUCH AS MAILBAGS Filed June 12, 1967 Sheet 3 of a 4/ L a f J 4 P8. 6

COUNTER Kb 43 i 2: 6.6

1956f WE Jean J. CHAZOT Lucien P. PUE HBER'IIY A {a INYENTORS:

Michel CAMBORNAC United States Patent Int. (:1. 1i07e 5/34 U.S. Cl. 209111.5 4 Claims ABSTRACT OF THE DISCLOSURE A radio sorting system for mechanically conveyed niailbags the label of which includes a radiation powered transponder is disclosed. The label is composed of two portions. The first main portion which includes said transponder is attached to the mailbag and adapted to rece ve on the one hand a written indication of the destination of the mailbag and on the other hand the second portion wlich is an index-key for coding the response signal of said transponder according to the written destination indication.

The present invention relates to an automatic sorting system for articles such as mailbags and more particular to articles of extremely varied shapes which are labelled and conveyed by a mechanical conveyor.

It is known that the mail is normally collected at a given moment in closed bags, each equipped with a label bearing the destination of its contents and fixed to the neck of the bag.

On their arrival at a sorting ofiice, the bags thus constituted are first divided into two categories, on the one hand the bags to be opened, that is to say those of which the contents have to be sorted in the ofiice and transferred to other bags bearing other destinations, on the other hand the bags in transit which have to be redispatched as they are to other centers.

The new bags formed and the bags in transit are then distributed, on leaving the oilice, for the various means of transport (rail, road and air) which they have to take.

In the sorting ofiices which are not yet equipped with mechanical handling means, the sorting of the incoming bags takes place by hand, officials taking the bags one by one from a lorry or a truck and carrying them to a truck selected depending on the information read on each label. This method is obviously lengthy, tedious and arduous.

In the mechanized sorting oflices, the incoming bags are conveyed by one or more mechanical conveyors, each of which leads to a sorting official installed in a fixed station. The latter reads the label on each bag and directs the bag towards its first destination in the sorting office either by deflecting it manually in the less highly developed installations or by striking a button on the keyboard in the most modern installations. The progress thus achieved is already considerable because the physical fatigue of the staff is greatly reduced and the rate of selection considerably increased.

Nevertheless, the time taken in finding and reading the label then in the push-button operation means that, in practice, an operator can scarcely deal with more than 500 to 600 bags per hour. On the other hand, the direction indication is given to the conveyor, not to the bag, so that the moment this leaves the conveyor the corresponding information is lost. It follows that during the travel of the bag, even inside one and the same sorting ofiice, it may be necessary to read the label several times which is a waste of time and of labor.

Since the mail bags do not lend themselves to the conventional means of marking using mechanical or photoelectric means, because of their very varied shapes and random orientation on the conveyors used, in order to permit automatic sorting during their passage over a mechanical conveyor in front of a fixed sorting station, it has been proposed that a radio responder, marked generally when the bag is filled, should be introduced into each bag or attached thereto, and a transmitter and a receiver installed at the fixed sorting station in such a manner that an electromagnetic energy transmitted in the form of a first signal called interrogation signal by the transmitter to said responder on the passage of each bag in front of said station, should be used by the responder to retransmit a second signal called the response signal which is characteristic of the destination of the bag and is used by said receiver to actuate means for switching the bags in the various sorting directions.

These responders generally comprise an input circuit comprising a receiving aerial and one or more oscillating circuits, on the other hand an output circuit comprising a transistorized oscillator fed by said input circuit by means of a diode, one or more oscillating circuits and a transmission aerial. They are relatively complicated with a fairly low coding capacity for their response signals in such a manner that they are ill-adapted to the requirements of postal sorting in their coding capacity and in the minimum cost price of the members used in large numbers. Furthermore, they are not connected to the label bearing the address in clear of the destination of the mailbag so that the coded indication of this address may be omitted or in disagreement with ifs indication in clear which is always useful, particularly for checking purposes.

The object of the invention is to increase the efiiciency and to reduce the cost price of the automatic postal sorting installations.

According to the invention, in an automatic sorting system for mailbags equipped with labels indicating their destination and with radio identification responders, on their passage over a mechanical conveyor in front of a fixed sorting station equipped on the one hand with a radio transmission and receiving device, on the other hand with means for controlling the routing of the mailbags conveyed by said conveyor, said labels comprise on the one hand at least one surface adapted to receive in clear the indication of the destination of the bag for human reading, on the other hand said radio responder incorporated in their thickness and comprising, apart from the means of transmitting a high-frequency response signal in response to a high-frequency interrogation signal from said transmission device, means for modulating said response signal permitting, through a selection of connections prepared in advance, said response signal to be modulated in accordance with the coded indication of the destination of the bag in such a manner that said receiving means control the routing of each bag in consequence.

According to a preferred embodiment of said labels, said responder circuit comprises a portion permanently and rigidly connected to said label and terminated by a selective connector for said modulation circuits and an interchangeable selection key adapted to be plugged into said connector and determining the marking of said label.

According to a preferred embodiment of said responder circuit, this comprises a ring counter dividing the duration of said response signal into a succession of elemental times with each of which there is associated a particular combination of said modulation circuits.

The above features and advantages as well as others will be clearer from reading the following description of a certain number of embodiments of the invention given by way of non-limiting example with reference to the accompanying drawings in which:

FIGS. 1 and 1a show respectively in plan view and in longitudinal section, a first embodiment of a responder label according to the invention;

FIG. 2 is a block diagram of a transmission chain comprising a responder label according to the invention;

FIGS. 3 and 3a show a preferred embodiment of a responder label according to the invention;

FIG. 4 is a basic diagram of a sorting station for mailbags with responder labels according to the invention;

FIG. 5 is a perspective view of an example of an embodiment of a sorting station in accordance with FIG. 4;

FIG 6 is a diagrammatic perspective view of another example of an embodiment of the sorting station accordin g to the invention;

FIG. 7 is a wiring diagram of an embodiment of the radio circuits of a label according to FIG. 2;

FIGS. 8a, 8b show an example of a simplified embodiment of a label responder circuit 1n accordance with FIG. 7;

FIG. 9 is a wiring diagram of a preferred embodiment of the circuits of a label according to the invention;

FIGS. 9a, 9b, 90 show an example of an embodiment of a responder circuit in accordance with FIG. 9;

FIG. 10 is a diagram of the receiving device for the response signals from a label having a response circuit in accordance with FIG. 9 and FIGS. 11 and 12 are respectively diagrams of the responder circuit and of the receiving circuit in a modification of the invention.

The responder label 10 illustrated in FIGS. 1 and 1a may, for example, have the usual dimensions of the labels for mailbags used in international service, namely about 6 x 12 cm. It comprises a rigid or semi-rigid insulating plate 20 comprising, on one of its faces, a radio circuit of small dimensions which is easy to mass-produce, either of the printed type with micro-miniaturized components added, or of the integrated type encased in a plastic insulating compound 30, and on its other face a direct or added impression, for example by means of an adhesive foil 40, of the written routing instructions for the bag to which it is attached by a cord 32 passing through an eyelet 31.

The transmission assembly illustrated in FIG. 2 comprises a transmitter 51 and a receiver 53 both installed at the sorting station and respectively equipped with aerials 51.1 and 531, and the radio responder carried by the plate 20. This comprises essentially an aerial 211, a circuit for tuning the aerial 21 to the transmission frequency F for the transmitter 51 and a detection and filtering stage 22 which supplies filtered rectified current on the one hand to an'oscillator at radio frequency f with which there is associated an aerial 231, on the other hand to a group 24 of intermediate-frequency modulation oscillators 240, 241-249 which may be connected in or disconnected individually or in accordance with combinations characteristic of the destination of the bag carrying the label, through removable connections 200 to 209.

Since the aerials 211 and 231 of the label pass in the immediate vicinity of the aerials 511 and 531 of the sorting station, the decoding of the response signal picked up by the aerial 531 designates the direction to be given to the bag passing through the sorting station.

The connections such as 200 to 209 of a large number of labels bearing identical responder circuits, for example in accordance with FIG. 2, may be prepared once and for all in such a manner as to respond to all the possible or reserved combinations to designate the various markings provided by one or more sorting oflices. The sorting offices where the bags are prepared are provided with sets of labels thus marked in advance for the various destinations which they have to serve, and a label corresponding to the destination of each bag is selected from this set.

Such a procedure implies the recovery, on arrival, of the labels, the unit-price of which, although low, is not negligible, in order to permit re-use of the empty bags.

In order to olfer the possibility of marking as required, the removable connections 200 to 209 should be in accessible forms, for example consisting of obvious eyelets between which the connection can be established by means of a clip of a kind common in stationery and removed equally easily.

FIG. 3 shows a preferred embodiment of a label which can be marked as required and which provides great flexibility of use and can be adapted to all coding systems. This label consists of a fixed portion which may be identical in all the labels and an interchangeable portion 90 which determines each marking.

The fixed portion 70 is permanently connected to the bag, for example by means of rings 33, 34 and comprises, on the one hand the adhesive foil 40 or other interchangeable support which bears the written indication of its destination, on the other hand a radio responder circuit which may be of the type illustrated in FIG. 2 or of any other type, particularly adapted to the high-capacity coding systems which will be described subsequently. It is terminated by a female connector into which there is plugged the interchangeable portion which constitutes a marking key establishing the connections characteristic of a given destination.

The marking key 90 may be a very simple printed circuit or, as indicated in FIG. 3a, which relates to the case where a binary code is used, a metal plate, the low cost of which is such that its recovery may not be regarded as imperative.

FIG. 4 shows an example of the layout of a sorting station in the path of an overhead conveyor, of which the rail 61, perpendicular to the plane of the figure, carries a bag .11 suspended, neck downwards, from pliers 12 in such a manner that its label 10 is located in a cylinder having a vertical axis centered on the pliers 12 and an axial section represented by the rectangle in broken lines 13. Immediately outside the boundary constituted by the rectangle 13 and in a plane perpendicular to the rail 61 there are disposed the transmission and receiving aerials 511 and 531, respectively connected, by screened conductors, to the transmitter 51 and to the receiver 53.

In order to reduce the power consumption of the transmitter 51 and to protect the receiver 53 from interference signals, a light barrier 521-522 permanently applies an inhibiting voltage to the transmitter 51 and to the receiver 53 except during the time when the cell 522 is obscured, by means of an amplifier 52 assembled with the transmitter 51 and receiver 53 in one and the same enclosure 50.

Furthermore, the aerials 511 and 531 maybe protected by a metal enclosure 54 acting as a Faraday cage and equipped, if necessary, with metal entrance and exit swingdoors, the opening of which is associated with the passage of each bag. In this case, the barrier 521-522 may be replaced by a simple contactor actuated by the operation of the gates.

FIG. 5 shows a perspective view of an embodiment of such a sorting station in the path of the overhead conveyor 60 with a first branching station 62 downstream of this sorting station. In this embodiment, the aerials 511, 531, the light barrier 521-522 and the assembly 50 are suspended from a gantry fixed at its center to the upper edges of the rail 61.

FIG. 6 shows a particular arrangement of a sorting station in the case of a belt conveyor 63. In order to improve the output of the aerials 511 and 531 Whatever the position of the label 10 with respect to the bag to which it is attached, while avoiding possible screen eifects, aerials are used each of which is composed of three radiating elements in a trirectangular trihedral, the top of which is connected to a screened conductor not illustrated. These aerials are disposed, with respect to the conveyor belt 63 which is of insulating material such as rubber or plastics material, in a zone in which the rollers 64 are omitted and replaced by a sliding plate 65 of plastics material such as polytetrafiuorethylene.

FIG. 7 shows an example of an embodiment of a responder circuit in accordance with the diagram in FIG. 2. In the input stage 21, the aerial 211 is coupled directly, by means of a suitable tap appropriately situated on an induction coil 212 forming, with a capacitor 213 in parallel with its terminals, a resonant circuit tuned to the frequency f. The stage 22 comprises a capacitor 222 connected in series with a diode 221 to the terminals of the capacitor 213, two resistors 223, 224 connected in series to the terminals of the capacitor 222 and two capacitors 225 and 226 connected in parallel with the resistors 223 and 224 respectively. The radio-frequency oscillator 23 comprises an aerial 231 coupled directly, by means of a tap appropriately situated on an induction coil 232 forming, with a capacitor 233 in parallel with its terminals, a resonant circuit tuned to the frequency f, a pnp transistor 234 the emitter of which is connected through a resistor 235 to the cathode of the diode 221 and through a capacitor 236 to its collector itself connected to a terminal of the capacitor 233 and the base of which is connected at the common point 227 to the resistors 223, 224 and to the capacitors 225, 226. The second terminal of the capacitor 233 is connected, at the common point 228, to the capacitors 213, 222, 226 and to the resistor 224.

The group 24 comprises a plurality of similar modulators such as 240 and 249, only these two of which have been illustrated. The modulators 240 to 249 are composed of resistor and capacitor circuits in preference to an induction-coil circuit in order to facilitate their construction in the form of printed or integrated circuits. The modulator 240 for example comprises an npn transistor 2400 the collector of which is connected through a load resistor 2401 and a. removable connection 200 to the cathode of the diode 221, while its base is connected on the one hand to the connection 200 through a resistor 2402 and on the other hand to the common point 228 through a resistor 2403, and the emitter is connected on the one hand to the common point 228 through a resistor 2404 and on the other hand to the base of the transistor 234 by means of a capacitor 2405. In order to cause the transistor 2400 to oscillate, a phase-shift circuit with resistors 2406, 2407 and capacitors 2408, 2409 couples its collector to its base, the resistors 2406, 2407 in series with the capacitor 2408 between these electrodes having their common point connected to the connection 200 through the capacitor 2409.

Thus the circuits 240 to 249 oscillate at intermediate frequencies If to I91, and, in consequence, those wherein the feed connections such as 200 and 209 are established, modulate the signal at the frequency f of the circuit 23.

If the number of circuits 240 to 249 in each label is equal to p, the number k of different markings which can be realized is thus equal to 2 for example: if p=l0, k: 1024. The intermediate frequencies If to Ifg have no limit other than being of a sufliciently low value in comparison with the frequency f to be able to modulate it conveniently but they may nevertheless be sufficiently high for the circuits 240 to 249 which produce them to have components of small dimensions. If F300 mc./s. for example, it is possible to have 111 60 mc./s., If 90 mc./s. Furthermore, printed circuits can be made with micro-miniaturized components in a plurality of layers, but the circuits 2400 to 2409 are nevertheless limited in number by the limited power which is received by the label and which has to be divided between the main and modulating oscillating circuits without the final level of reception dropping below the minimum threshold estimated at about 1 microvolt per meter.

FIGS. 8a and 8b show an example of an embodiment of such a circuit in simplified form in accordance with the technique of printed circuits with micro-miniaturized components, on the two faces of an insulating board. On the face illustrated in FIG. 8a, there is seen the receiving aerial 211, the induction coil 212 and the capacitor 213, the diode 221, the capacitor 222 and the center point 227, here designated by the letter C, which is connected to the terminals A and B of the capacitor 222 on the one hand through the resistor 223 and the capacitor 225 in parallel, on the other hand through the resistor 224 and the capacitor 226 in parallel, and which is connected to the base of the transistor 234, the resistor 235 which connects the emitter of this to the diode 221 through the terminal A, the aerial 231 and the induction coil 232, the ends of which are connected to the collector of the transistor 234, the one directly and the other by means of the terminal B and the capacitor 233. The points A, B, C are terminals common to both faces of the board. The second face thereof, which is illustrated in FIG. 8b, combines the modulation circuits 240 to 249 in a single circuit comprising a pnp transistor 2400, to the base of which there are connected, in parallel, ten circuits, each of which comprises, in series, a resistor 2407 to 2497 and a. capacitor 2408 to 2498 and may be connected selectively through a removable connection 200 to 209 to the collector of the transistor 2400 by means of the resistor 2406 and to the point A by means of the capacitor 2409.

The points A and B are connected respectively to the collector and to the emitter of the transistor 2400 by means of the resistors 2401, 2404 and to one another through the two resistors in series 2402 and 2403 the common point of which ensures the biassing of the base of the transistor 2400. The emitter of this is further connected to the point C, that is to say to the base of the transistor 234, by means of the capacitor 2405.

The labels which can be marked as required, such as that illustrated in FIG. 3, further enable a coding system to be used according to which the return Wave is modulated by a limited number of intermediate frequencies in accordance with successive combinations equally distributed over the time of the response. If this time is divided into n moments during each of which one of the combinations of p frequencies can be used, the gross capacity of the code is K=2 For a given value of the product np, the same code capacity K may be obtained for different values of n and p. n and p may be selected in such a manner that the number of code elements n+p is a minimum for example for n+p=l0 that is to say K=1024, it is possible to take n=5 and 12:2. Nevertheless, if a particular code combination, for example the combination in which the two modulation frequencies are present, is associated with a start pulse to ensure the synchronization between the code pulses transmitted by the label and the decoding device on reception, the number of combinations which can be used drops to 3 =243 and if, in addition, with the object of safety, it is desired to exclude the combination in which the two modulation frequencies are absent, all that remains for the code are the thirty-two combinations of the five-unit code.

FIG. 9 shows by way of example the basic diagram of a responder circuit for ten unit elements and two frequencies f and f adapted to a code in which the presence of a signal at the frequency and the absence of a signal at the frequency f has been selected as a start signal, the code signals being characterized by the presence of a signal at the frequency f in each of the nine unit elements of the code and differentiated by the distribution between these unit elements of four signals at the frequency f said code thus having a capacity of C =l26 combinations.

The responder circuit in FIG. 9 differs essentially from that in FIG. 7 by its coding system. Their receiving, modulation and transmission circuits are similar except that since this latter responder only uses two frequencies it is an advantage to equip it with two independent transmitters oscillating respectively at the frequencies f and f each having its own aerial circuit and own aerial and being on-off modulated in accordance with the coded marking of the label. In order to facilitate the comparison between the similar circuits in FIGS. 7 and 9, the same reference numerals have been used to designate the homologous members and the reference numerals of the supplementary transmission circuit have been marked with primes. Consequently, the receiving, modulation and transmission circuits of FIG. 9 which are identical to the circuits 21, 22, 240 and 23 in FIG. 7 except with regard to the emitter connections of the transistor 2400 and base connections of the transistors 234, 234', will not be described again.

The emitter of the transistor 2400 is connected through the capacitor 2405 and the terminal C, on the one hand to the stepping input of a counter 71, on the other hand, by means of an AND gate 74 to the base E of the transistor 234 and by means of an AND-NOT gate 75, to the base E of the transistor 234'.

The counter 71 is a ring counter with four trigger circuits with a decade connection, the feed inputs of which are connected to the terminals A and B of the capacitor 222. The eight outputs of the counter 71 are connected to eight inputs of a decoder 72 having six outputs which are active respectively when the number counted by the counter 71 is 3, 5, 6, 7, 9 and 0. The zero output of the decoder 72 is connected on the one hand to the blocking input of the gate 75, on the other hand, by means of an OR-gate 73 to the release input of the gate 74.

The operative outputs of the four trigger circuits of the counter 71, which are active respectively when this counts 1, 2, 4, and 8, and the first five outputs of the decoder 72 are connected through diodes 81 to 89 to the first nine terminals of a female connector with ten terminals, the tenth of which is connected to the second input of the gate 73. The marking key 90 which is here a simple metal plate cut out in accordance with the binary number characteristic of a given marking, closes the circuit between the diodes 81 to 89 corresponding to this marking and the gate 73.

When the energy received by the aerial 211 is sufficient for the charge of the capacitor 22 to reach an adequate voltage, for example of the order of volts, the oscillator 240 supplies the counter 71-and the gates 74, 75 with a substantially rectangular signal at a frequency selected in such a manner as to facilitate the counting, for example of the order of 2 kc./ s. When the counter 71 is at zero, the signal which appears at the Zero output of the decoder 72 releases the gate 74 and closes the gate 75 in such a manner that the negative half-wave of the signal supplied by the modulator 240 switches on the transistor 234 while the transistor 234 remains switched off. The start signal having thus been transmitted, the counter 71 advances in such a manner that the gate 75 is opened and at each of the following nine periods of the modulator 240 the transistor 234' is switched on and the signal at the frequency f is transmitted, while the signal at the frequency f is only transmitted when the marking key 90 comprises a tooth opposite the corresponding terminal at the moment in question.

FIGS. 9a, 9b, 90 show an example of an embodiment of printed and integrated circuits with three layers of the circuit in FIG. 9. FIG. 9a differs from FIG. 8a only in the elimination of the resistors 223, 224 and of the capacitors 225, 226. In addition, the terminal which is connected to the base of the transistor 234 is there designated by the letter E The layer illustrated in FIG. 9b comprises the modulation circuit 240, the various elements of which have been numbered as in FIG. 9 to facilitate the comparison between these two illustrations, the counter 71 and the decoder 72, divided for reasons of convenience into two parts 721 and 722, of which the first has two outputs active respectively when the counter 71 indicates zero and 9 and the second has four outputs which are active respectively when the counter 71 indicates 3, 5, 6 and 7. These six outputs, as well as the outputs 1, 2, 4, 8 of the counter 71 lead to the terminals 0 to 9 which communicate with the third layer illustrated in FIG. 9c. This carries the female connector adapted to receive a marking key such as and comprising the nine diodes 81 to 89, the cathodes of which are connected to the outputs 1 t0 9 of the counter 71 and of the decoders 721, 722. Furthermore, it comprises the OR gate 73, the AND gate 74 and AND-NOT gate 75 illustrated together and the transmission circuit 23'. It will be seen that the feed terminals A and B are common to the three layers, the output terminal C of the modulation stage 240 is common to the circuits illustrated in FIGS. 9b, 9c and the terminal E controlling the transistor 234 through the gate 74 is common to the circuits in FIGS. 9a and 90. FIG. 911 further shows that in order to avoid the crossing of connections, those which connect the outputs 1, 2 and 8 of the counter 71 to the terminals bearing the same number are printed on the back of the support for this circuit as indicated by their illustration in broken lines.

FIG. 10 is a basic diagram of the receiving and decoding device for the response signals of a label in accordance with FIGS. 9 and 9a, 9b, 9c. In this case, two independent receivers, tuned respectively to the frequencies f and f and controlled jointly by the detector 52 for the passage of a bag are installed at the sorting station. Each of them comprises an aerial 531, 541, an amplifier 532, 542, a local oscillator 533, 543 and a mixer and detector circuit 534, 544. The output of the receiver 544 is connected to the blocking input of an AND-NOT gate 55 and to one of the two inputs of an AND-gate 56. The output of the receiver 534 is connected to the second input of the gates 55 and 56. The output of the AND-NOT gate 55 is connected to the operating input of a trigger 57, the operative output of which controls a AND-gate 58 having its second input connected to the output of the receiver 544 and an AND-gate 59 having its second input connected to the output of the gate 56. The output of the gate 58 is connected on the one hand to the stepping input of a shift register 63 comprising ten trigger circuits, on the other hand to the stepping input of a counter 66 which, on the ninth pulse which it receives after its return to zero transmits a reset pulse to the trigger circuit 57. The output of the gate 59 controls the operation of the first trigger circuit in the shift register 63. This is returned to zero as well as the counter 66 by the signal supplied by the amplifier 52 when the light sensitive cell 522 is obscured by the arrival of a bag at the sorting station. The outputs of the shift register 63 are connected to the inputs of a decoder 64 through a set of AND-gates 65, the release inputs of which are connected in parallel to the inoperative outputs of the trigger circuit 57.

Thus it will be seen that the marking of the label of each bag is transferred without any possible displacement to the utilisation members through the decoder 64.

The setting of the trigger circuit 57 by the start signal characterized by the presence of a signal at the frequency i in the absence of a signal of the frequency f and detected by the gate 55 determines the control of advance, through the pulses at the frequency f passing through the gate 58, of the shift register 63 as well as the writing of the digit one in the input trigger circuit thereof when the signals at the frequencies f and f are present simultaneously at the inputs of the gate 56. The resetting of the trigger circuit 57 by the counter 66 in response to the ninth stepping pulse which is applied thereto at the same time as to the shift register 63 after their common return to zero locks the shift register in the state in which the trigger stages 2 to .10 reproduce the marking of the key 90. The first trigger stage of the shift register 63 is not connected to the decoder 64 because the writing of a digit 1 and the advance are controlled by one and the same pulse so that the first trigger stage can only act as an input trigger state.

Furthermore, the restoration to zero of the register 63 and of the counter 66 on the arrival of the fresh bag at the sorting station avoids any repercussion of a defect in operation of the label of one bag on the routing of the following one.

FIGS. 11 and 12 relate to a particularly condensed mode of coding wherein the response signal is divided into ten unit elements and one and the same frequency F is used for the interrogation and response signals which are on-ofi modulated at a clock frequency fH. The label bears the responder circuit illustrated diagrammatically in FIG. 11 and comprising a single aerial 111 connected to a receiver-transmitter 112, the oscillating circuit of which comprises a variable reactance member such as a variablecapacity diode enabling its tuning frequency to be varied. The transmitter-receiver 112 transmits the power received by means of a detection circuit 113 with two filters 114 and 115, the first of which is a band-pass filter eliminating the DC. component and the frequency F and consequently only allowing through the signals at the clock frequency )H and the second is a low-pass filter. Of the filters 114 and 115, the first supplies a ring counter 116 with stepping pulses at the clock frequency and the second supplies it with a DC. feed voltage.

The outputs of the ring counter 116 lead to a connector 117 and are connected selectively by the marking key 90 to the terminals of the variable capacity diode of the re ceiver-transmitter 1.12, of which the retransmission wave at the frequency F is thus modulated, through variation in the tuning of its oscillating circuit, depending on the connections established by the key 90.

The fixed equipment illustrated diagrammatically in FIG. 12 comprises an aerial 121, a transmitter-receiver 122, a demodulator 123, a detection circuit 124, a ring distributor 125, a register 126, a decoder 127 and a clockfrequency oscillator 128 controlled by a programmer 120 the operation of which is triggered by the signal supplied by the amplifier 52 when a bag arrives at the sorting station.

The programmer 120 and the clock-frequency oscillator 128 constitute the sole centralized control device for the whole assembly. On the arrival of a bag, the programmer releases the oscillator 128 which transmits a train of ten pulse at the repetition frequency fH. These pulses, on the other hand modulate the wave of frequency F transmitted by the transmitter-receiver 122, and on the other hand cause the ring distributor 125 to advance step by step.

The wave of frequency F thus modulated is received by the aerial 111 and the receiver 112, detected at 113 and transmitted in the form of stepping pulses and of a feed voltage by the filters .114, 115 to the ring counter 116. This therefore successfully feeds the ten terminals of the connector 117, the voltage of which is transmitted to the element for regulating the tuning frequency of the receiver-transmitter 112 when the marking key 90 is equipped with a tooth at their lever. On reception, the signals received by the transmitter-receiver 122 are successfully directed towards each of the ten trigger circuits 126 and those to which the modulated signals are applied as a result of the coded marking of the key 90 become operative in such a manner that the corresponding destination is indicated by the decoder 127.

What we claim is:

1. An automatic sorting system for mailbags comprising a mechanical conveyor for conveying said mailbags; at least one fixed sorting station equipped with radio transmitting and receiving means and with means for controlling the routing of said mailbags depending on coded signals received by said receiving means in response to interrogation signals transmitted by said transmitting means; labels respectively attached to said mailbags and composed of a main portion attached to the mailbag and comprising at least one surface adapted to receive a Written indication of the destination of said mailbag, means for receiving said interrogation signals, radiation powered means for transmitting modulated coded signals in response to said interrogation signals, and a connector for controlling the modulation of said signals, and a removable and interchangeable portion to be plugged into said connector for establishing the connections determining the modulation which results in the coded signal corresponding to the written destination indication carried by the label.

2. An automatic sorting system as claimed in claim 1 wherein said fixed radio transmitting means comprise a radio-frequency interrogation signal transmitter and a lowfrequency oscillator which modulates said interrogation signal in such a manner as to determine clock pulses, said receiving means of the label comprise an aerial associated with an oscillating circuit comprising a reactance member which is variable depending on the voltage applied thereto, said transmitting means of the label comprising a ring counter power supplied by said oscillating circuit through diode means and advancing in response to said clock pulses, said ring counter successively applying voltage to the terminals of said connector which are selectively connected to said variable reactance member through said plugged in removable and interchangeable portion.

3. An automatic sorting system for mailbags comprising a mechanical conveyor for conveying said mailbags; at least one fixed sorting station equipped with radio transmitting and receiving means and with means for controlling the routing of said mailbags depending on coded sig nals received by said receiving means in response to interrogation signals transmitted by said transmitting means; labels respectively attached to said mailbags and comprising at least one surface adapted to receive a written indication of the destination of the corresponding mailbag, means for receiving said interrogation signals, radiation powered means for transmitting versatile coded signals in response to said interrogation signals, and means for selecting the coded response signal of each label in accordance with the written destination indication carried by said label; said radiation powered transmitting means comprising a plurality of selectable modulation circuits and said selecting means being adapted to elfect the connection of any combination of said modulation circuits.

4. An automatic sorting system for mailbags comprising a mechanical conveyor for conveying said mailbags; at least one fixed sorting station equipped with radio transmitting and receiving means and with means for controlling the routing of said mailbags depending on coded signals received by said receiving means in response to interrogation signals transmitted by said transmitting means; labels respectively attached to said mailbags and comprising at least one surface adapted to receive a written indication of the destination of the corresponding mailbag, means for receiving said interrogation signals, radiation powered means for transmitting versatile coded signals in response to said interrogation signals, and means for selecting the coded response signal of each label in accordance with the written destination indication carried by said label; said radiation powered transmitting means comprising a ring counter dividing the duration of said coded signals into a succession of elemental times with each of which is associated a particular combination of said modulation circuits through said selecting means.

References Cited UNITED STATES PATENTS 2,910,579 10/1959 Jones 340-152 3,286,811 11/1966 McWilliams 198-38 M. HENSON WOOD, JR., Primary Examiner. R. A. SC-HACHER, Assistant Examiner.

US. Cl. X.R. 340-152

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