Method and apparatus for detecting and counting articles

• US 5,031,156 A
• Filed: 12/12/1989
• Issued: 07/09/1991
• Est. Priority Date: 06/20/1986
• Status: Expired due to Fees

• Current Assignee: Heidelberg Finishing Systems, Inc. (Goss International Americas, LLC)
• Original Assignee: EDS Technologies, Inc.
• Inventors: Sawabini, Charles E., Johnson, William A., Watts, Leonard A.
• Primary Examiner(s): Pihulic, Daniel T.
• Application Number:
  US07/449,444
• Time in Patent Office: 574 Days
• Field of Search: 367/87, 367/93, 367/95, 367/96, 367/100, 367/117, 367/124, 367/126, 209/537, 377/8, 235/98 C, 235/98 R
• US Class Current: 367/95
• CPC Class Codes: G06M 7/00 Counting of objects carried by a conveyor

Abstract

Articles, moving along a delivery path, are counted by directing a stream of pressurized air toward one major surface of the passing articles, the direction of the air stream being transverse to the direction of travel. Sensors arranged about the air stream detect the acoustic signal which varies with changes in the profile of the passing articles, exemplified by signatures. The detected acoustic signal is divided into a plurality of frequency ranges which, in one preferred emboidment, are averaged to reduce the effect of noise which may be present in only limited ones of the frequency bands. The averaged signals are then compared against thresholds to determine the instantaneous state of the articles, exemplified by a signature stream, to generate count signals.

Claims

1. Apparatus for monitoring articles delivered along a path comprising:

means for directing an air jet toward the articles,

sensor means positioned to sense frequencies and associated amplitudes of sound waves generated by acoustic interaction of said air jet with the articles;

means governed by said sensed acoustic interaction for generating signals which vary in accordance with the frequencies and associated amplitudes of the sound waves generated by said acoustic interaction; and

means responsive to said generated signals for monitoring first, second, and third states of said articles.

2. The apparatus of claim 1 further comprising means responsive to said generated signals for accumulating count signals.

3. The apparatus of claim 1 wherein the signal generating means generates electrical signals having amplitudes at selected frequencies that vary respectively in accordance with the amplitudes at corresponding frequencies of the sound waves.

4. An apparatus for counting signatures conveyed in a first direction along a path, comprising:

means positioned adjacent the conveying path for transmitting a pressurized air jet in a second direction at an oblique angle to the first direction to interact with the individual signatures in succession;

sensing means positioned adjacent the path for sensing sound waves having varying frequencies and associated amplitudes generated by the pressurized air jet interacting successively with the signatures moving along the path;

means responsive to the varying frequencies and associated amplitudes of the sensed sound waves for generating signals characteristic of the interaction with respective signatures; and

means responsive to said generated signals for counting said signatures in succession.

5. The apparatus of claim 4, wherein said sensing means comprises a plurality of sensors positioned around said air jet, each sensor generating an output signal having predetermined characteristics which vary in accordance with a frequency and associated amplitude of the generated sound waves.

6. The apparatus of claim 5 wherein said signatures are both overlapped and spaced.

7. The apparatus of claim 5 wherein said sensors are arranged at intervals about an imaginary circle surrounding said air jet.

8. The apparatus of claim 5 wherein the air jet transmitting means includes means for providing air pressure in the range of from approximately 30 to 50 psi.

9. The apparatus of claim 8 wherein the air pressure is of the order of 40 psi.

10. The apparatus of claim 5 wherein the air jet transmitting means comprises an exit nozzle having a bore coupled to a source of pressurized air and having a bore length approximately between 0.40 and 1.9 inches.

11. The apparatus of claim 10 wherein bore length is of the order of 0.9 inches.

12. The apparatus of claim 10 wherein said bore has a diameter in the range from approximately 0.03 to 0.06 inches.

13. The apparatus of claim 12 wherein bore diameter is of the order of 0.042 inches.

14. A method of monitoring articles delivered along a path, comprising the steps of:

directing an air jet toward the articles;

sensing frequencies and associated amplitudes of sound waves generated by acoustic interaction of the air jet with the articles;

generating signals which vary in accordance with the frequencies and associated amplitudes of the sound waves generated by said acoustic interaction; and

monitoring first, second, and third states of the articles in accordance with the variations in the generated signals.

15. A method for counting articles comprising the steps of:

moving said articles so that at least a leading portion of each article is arranged at a spaced interval behind the leading portion of each adjacent downstream article, said articles being moved past a detecting location;

directing an air jet for successively striking at least the leading portion of the articles as they pass the detecting location to interact with the moving articles for generating sound waves having varying frequencies and associated amplitudes;

detecting the frequencies and associated amplitudes of the generated sound waves; and

generating a detecting signal at times when a predetermined frequency is detected; and

evaluating the amplitude associated with said predetermined frequency for generating a count signal per valid leading portion.

16. The method of claim 15 wherein said predetermined frequency comprises a sound wave having a frequency above 1,000 Hz.

17. The method of claim 15 wherein said detecting step further comprises converting the sound wave into an electrical signal having a frequency which is a function of the sound wave.

18. Detection apparatus for detecting at least one characteristic in a profile of articles moving along a delivery path, said apparatus comprising:

means for directing a jet of pressurized air toward one surface of said articles, wherein interaction of the air jet with the articles generates an acoustic signal which varies with variations in the profile of the articles in the delivery path;

sensor means including a plurality of acoustoelectric sensors arranged about said air jet in a manner to enhance directivity of said sensor means, each sensor including means for generating an electric signal corresponding to said acoustic signal received by the sensor;

means for summing the generated electric signal of said sensors for obtaining a first output signal;

filter means coupled to said summing means for filtering out unwanted frequencies in the first output signals of said summing means;

a plurality of band pass channels each being coupled to said filter means for passing a predetermined frequency band, the frequency bands of each channel being different; and

detection means responsive to the frequency bands of said channels for generating a first detection signal representative of a particular characteristic in said profile.

19. The apparatus of claim 18 wherein said detection means further comprises second summing means for summing the frequency bands of said band pass channels to obtain a second output signal;

means coupled to said second summing means for developing a predetermined threshold level; and

first comparator means for comparing said threshold level with the second output signal from said second summing means for generating said detection signal when the second output signal of said second summing means is of a predetermined value relative to said threshold level.

20. The apparatus of claim 19 further comprising second threshold generating means coupled to said second summing means for generating a second threshold level for detecting a second characteristic of said profile;

second comparison means for comparing the output of said second summing means with said second threshold level for generating a second detecting signal when the output of said second summing means is of a predetermined value relative to said second threshold level.

21. The apparatus of claim 20 wherein said second threshold generating means comprises low-pass filter means extracting a level from the output of said second summing means representative of the second characteristic of said profile, and means coupled to said low-pass filter means for producing said second threshold level.

22. The apparatus of claim 21 further comprising a branch path for coupling the output of said second summing means to said second comparator means, said branch path having a matched filter for matching a transient response in said branch path with a transient response of said low-pass filter means.

23. The apparatus of claim 22 further comprising a second branch path for coupling the output of said second summing means to said second comparator means, said second branch path including match filter means for matching a transient response of said second branch path to the transient response of said low-pass filter means.

24. The apparatus of claim 23 wherein said second branch path further comprises means for subtracting an output of said low-pass filter means from said second summing means.

25. The apparatus of claim 24 wherein said second branch path further includes half-wave rectifier means for passing only signals of one polarity and means for converting said half-wave rectifier signals to a d.c. signal.

26. The apparatus of claim 18 wherein each said band pass channel comprises a band pass filter differing from each adjacent band pass filter by one-half octave.

27. The apparatus of claim 26 wherein said band pass filter means comprises a switched capacitor filter means.

28. The apparatus of claim 18 wherein each band pass channel comprises filter means for passing a predetermined frequency band and means for converting said frequency band of said filter means to a d.c. signal.

29. The apparatus of claim 28 wherein said filter means comprises a four-pole Chebychev filter.

30. A method for counting signatures conveyed in a first direction along a path, comprising the steps of:

transmitting a pressurized air jet in a second direction at an oblique angle to the first direction to interact with the individual signatures in succession;

sensing varying frequencies and associated amplitudes of sound waves generated by the pressurized air jet interacting successively with said signatures;

generating signals, in response to the varying frequencies and associated amplitudes of the sensed sound waves, characteristic of the interaction with respective signatures; and

summing said signals for counting said signatures.

31. The method of claim 30 further including the step of positioning a plurality of sensors adjacent the path at intervals about an imaginary circle surrounding said air jet.

32. Apparatus for monitoring articles delivered along a path comprising:

means for directing an air jet toward the articles,

sensor means positioned to sense interaction between said air jet and the articles;

means, including a spectrum analyzer, governed by said sensed interaction for generating a signal which varies in accordance with sound waves generated by said interaction; and

means responsive to said generated signal for monitoring said articles.

33. An apparatus for counting spaced and overlapping individual signatures conveyed in a first direction along a path, comprising:

means positioned adjacent the conveying path for transmitting a pressurized air jet in a second direction at an angle to the first direction to interact with the individual signatures in succession;

sensing means positioned adjacent the path, including a plurality of sensors positioned around said air jet at equispaced intervals about an imaginary circle surrounding said jet, for sensing sound waves generated by the pressurized air jet interacting successively with the overlapping and spaced signatures moving along the path, each sensor generating an output signal having predetermined characteristics which vary in accordance with a frequency of the generated sound waves;

means responsive to the sensed sound waves for generating signals characteristic of the interaction with respective overlapping and spaced signatures; and

means responsive to said generated signals for counting said overlapping and spaced signatures in succession.

34. A method for monitoring articles delivered along a path comprising the steps of:

directing an air jet toward the articles;

sensing interaction between said air jet and the articles;

generating a signal, using a spectrum analyzer governed by said sensed interaction, which varies in accordance with sound waves generated by said interaction; and

monitoring said articles in response to said generated signal.

35. A method for counting spaced and overlapped indiviudal signatures conveyed in a first direction along a path, comprising the steps of:

transmitting a pressurized air jet in a second direction at an angle to the first direction to interact with the individual signatures in succession;

positioning a plurality of sensors adjacent the path at equispaced intervals about an imaginary circle surrounding said air jet;

sensing sound waves generated by the pressurized air jet interacting successively with said signatures;

generating, from each sensor, an output signal having predetermined characteristics which vary in accordance with a frequency of the generated sound waves;

generating signals characteristic of the interaction with respective overlapping and spaced signatures; and

summing said signals for counting said signatures.

36. Apparatus for monitoring articles delivered along a path comprising:

means for directing an air jet toward the articles,

sensor means positioned to sense acoustic interaction between the air jet and the articles;

means, governed by said sensed interaction, including a spectrum analyzer for selecting a plurality of frequencies corresponding to frequencies of the sensed interaction, for generating a signal having an amplitude which varies in accordance with the amplitude of the selected frequencies;

means responsive to said generated signal for monitoring said articles.

37. A method for monitoring articles delivered along a path comprising the steps of:

directing an air jet toward the articles,

sensing acoustic interaction between said air jet and the articles;

selecting a plurality of frequencies corresponding to frequencies of the sensed interaction, with a spectrum analyzer governed by said sensed interaction;

generating a signal having an amplitude which varies in accordance with the amplitude of the selected frequencies; and

monitoring said articles in accordance with the generated signal.