PULSE INTERROGATION ARTICLE-SORTING SYSTEM

• US 3,713,102 A
• Filed: 04/23/1970
• Issued: 01/23/1973
• Est. Priority Date: 04/23/1970
• Status: Expired due to Term

• Current Assignee: Stephen J. Martin
• Original Assignee: Stephen J. Martin
• Inventors: Martin, Stephen J.
• Primary Examiner(s): Tubbesing, T. H.
• Application Number:
  US05/031,141
• Time in Patent Office: 1,006 Days
• Field of Search: 340/149R,171R,258R 343/6.5SS
• US Class Current: 340/5.8
• CPC Class Codes: B07C 3/12 using electric or electronic detecting means B07C3/14 takes precedence
• CPC Class Codes: B65G 47/496 by use of magnetic responsive means
• CPC Class Codes: G06K 19/0672 with resonating marks
• CPC Class Codes: G06K 7/086 sensing passive circuit, e.g. resonant circuit transponders

Abstract

A pulse interrogation article-sorting system for identifying and directing articles along a distribution network, such as passenger baggage along a conveyor therefor at an airline terminal. A particular form of the article-sorting system for airline baggage includes a conveyor having both a collection section along which baggage is accumulated and a distribution section providing a plurality of distribution branches or stations respectively corresponding to particular flight destinations and into which articles of baggage are selectively diverted in accordance with the destinations thereof. A plurality of diverters disposed in respective association with the distribution branches are operative selectively to effect diversion thereinto of individual articles of baggage being advanced along the conveyor. Each article of baggage carries a tag equipped with a normally passive identification responder operative to transmit an electromagnetic identification signal representative of the destination indicated by the tag in response to receipt of sharply pulsed electromagnetic interrogation signals emitted by a transmitter for interception by each article of baggage and the responder-equipped tag carried thereby. A receiver having sensor circuitry responsive to the identification signals provides both logic circuitry for processing the signals to identify the same in terms of their destination-distinguishing characteristics and control means connected with the diverters and with the logic circuitry and operative to actuate the diverter corresponding to the particular signal identified by the logic circuitry. Accordingly, whenever the logic circuitry establishes the identity of a particular identification signal transmitted by an identification responder being intercepted by the interrogation signals, the diverter corresponding to that identification signal is actuated to segregate or divert into the appropriate branch the article of baggage carrying such transmitting responder.

Claims

1. An article-identification system, comprising an interrogator operative to produce at a particular location through which such article passes a succession of sharply pulsed interrogation signals each having essEntially the same frequency, a normally dormant identification responder for transport in association with such article through said location and including a tuned circuit having a predetermined resonant frequency different from that of such interrogation signal but responsive thereto so as to be energized thereby and produce an article-identifying signal having predetermined frequency characteristics corresponding to such resonant frequency, a sensor receptive to such identification signal and operative to establish such frequency characteristics thereof, and utilization means connected with said sensor for evidencing as a function of such established frequency characteristics the presence of said identification responder and associated article at such location, whereby a plurality of such articles respectively equipped with normally dormant identification responders having tuned circuits providing differing resonant frequencies all responsive to the same interrogation signals can be differentiated one from another.

2. The system of claim 1 in which said pulse generator produces interrogation signals having a pulse width of the order of 2 microseconds.

3. The system of claim 1 in which said interrogator further includes an inductance connected with said pulse generator and defining a signal-transmitting device positioned adjacent said particular location to transmit interrogation signals thereat, and in which said signal-transmitting device is tuned to the frequency of the interrogation signals produced by said pulse generator.

4. The system of claim 3 in which said inductance is a relatively large coil of low resistance.

5. The system of claim 4 in which said inductance comprises 1 turn and has a resistance of about 0.1 ohm.

6. The system of claim 3 in which said interrogator is operative to limit the voltage present across said inductance to a relatively low value and thereby limit the electric components in the signal field developed by said inductance to low values so as to minimize electromagnetic radiation therefrom.

7. The system of claim 3 in which said interrogator developes a power ratio per identification signal pulse of at least about 2 milliwatts average power per square foot of area at said predetermined location through which such article may pass.

8. The system of claim 1 in which said sensor includes a zero axis crossing detector so as to establish the frequency characteristics of any such identification signal by determining the zero axis crossings of any 1 cycle thereof.

9. The system of claim 8 in which said sensor further includes a broad-band amplifier interposed between said receiver inductance and zero axis crossing detector, and a threshhold detector coupling said broad-band amplifier and zero axis crossing detector.

10. The system of claim 9 in which said sensor further includes an interval counter for measuring the interval between the zero axis crossings determined by said zero axis crossing detector.

11. The system of claim 1 in which said utilization means includes a logic component operative to establish the count number within a finite time period representing such frequency characteristics, and in which said logic component includes a high-count-hold logic circuit and a hold-count timer connected therewith.