Method and apparatus for verifying whether documents have been separated from an opened envelope

• US 5,655,668 A
• Filed: 09/04/1996
• Issued: 08/12/1997
• Est. Priority Date: 12/31/1992
• Status: Expired due to Fees

• Current Assignee: Neopost Industrie BV
• Original Assignee: Hadewe BV
• Inventors: Drenth, Klaas
• Primary Examiner(s): Terrell, William E.
• Assistant Examiner(s): NGUYEN, TUAN N
• Application Number:
  US08/706,066
• Time in Patent Office: 342 Days
• Field of Search: 209/556, 209/559, 209/565, 209/601, 209/603, 209/604, 209/900, 271/262, 271/263, 271/264, 271/265.01, 271/265.02, 271/265.03, 271/265.04, 53/52, 53/381.3, 53/381.5, 53/381.7, 53/492, 53/504, 324/230
• US Class Current: 209/603
• CPC Class Codes: B43M 7/02 Devices for both opening envelopes and removing contents
• CPC Class Codes: Y10S 209/90 Sorting flat-type mail

Abstract

A method and apparatus for checking whether documents have been separated from an opened envelope includes conveying an envelope past an input transducer which measures a characteristic, based on light shown through the envelope, of each individual envelope along a measuring path parallel to the direction of movement of the envelope. From the measured characteristic, a value profile is determined, from which a reference value for each envelope is determined. The value profile is used then to calculate an extreme limit value for each envelope. An envelope-suspect signal is generated if the value profile lies beyond the limit value over a specified minimum substantially continuous measuring distance. The system calculates the values for each envelope, and accordingly, envelopes of greatly diverse characteristics may be reliably checked in random order.

Claims

1. A method for separating documents from an opened envelope and checking whether documents have been separated from the opened envelopes, comprising the steps of, for each individual opened envelope to be checked:

separating contents from an opened envelope;

subsequently conveying the opened envelope on a measuring path past at least one input transducer, which measures a predetermined characteristic of that envelope along a measuring path distance extending over the envelope,

determining a value profile from the measured characteristic along said measuring path distance,

determining a reference value for that individual envelope from the value profile,

determining an extreme limit value for that individual envelope from the reference value, and

generating an envelope-suspect signal for that individual envelope if the value profile lies beyond the extreme limit value over a predetermined minimum substantially continuous distance.

2. A method according to claim 1, wherein each envelope is conveyed along the input transducer in a condition opened along three sides and unfolded about a fourth side, a smallest or greatest value of the value profile which is substantially constant over a path of at least a predetermined length is identified and a value corresponding with the substantially constant value of that part is stored as a reference value, and the limit value is determined by adding a tolerance value to this reference value.

3. A method according to claim 2, wherein the value profile is made up of separate, successive values, the smallest or greatest value of the value profile which is substantially constant over a path of at least a predetermined length is identified by identifying series of substantially identical values occurring in succession at least a predetermined number of times and selecting therefrom the series with the smallest or the greatest value.

4. A method according to claim 2, wherein, in determining the reference value, parts of the value profile below or above a predetermined threshold value are skipped.

5. A method according to claim 2, wherein prior to the verification of the envelope a value measured by the input transducer is stored as a base value associated with that envelope and the values measured are stored and processed in the form of differences with regard to the base value.

6. A method according to claim 1, comprising:

storing a value measured by the input transducer prior to the passage of the envelope as a base value,

identifying a first part of the value profile of a substantially constant value, which is limited by parts with deviating values and which has a length within a predetermined range,

identifying a second, adjacent part of the value profile of a substantially constant value and a predetermined minimum length,

determining the difference between the substantially constant values of the first and second parts,

storing said difference as the reference value, and determining the limit value by adding once or twice the reference value and a tolerance value to the base value.

7. A method according to claim 6, wherein the value profile is made up of separate, successive values, wherein

as a first part, a series of substantially identical values, whose number lies between a predetermined minimum and a predetermined maximum, are identified, and

as an adjacent part, a series including at least a predetermined number of substantially identical values are identified.

8. A method according to claim 6, wherein said difference is compared with a predetermined threshold value, and is stored as a reference value only if it lies outside a range limited by the threshold value.

9. A method according to claim 6, wherein, if two or more parts of a value profile have been identified, which have a substantially constant value, are limited by parts with deviating values and have a length lying within a predetermined range, the part with the greatest substantially constant value is identified as said first part of the value profile.

10. A method according to claim 4, wherein, after the passage of an envelope, an envelope-suspect signal is moreover generated if no value associated with that envelope is stored as a reference value.

11. A method according to claim 4, wherein said tolerance value and said threshold value are approximately equal.

12. A method according to claim 5, wherein the envelope is conveyed along at least two input transducers in positions mutually spaced transversely to the direction of conveyance and for each input transducer a base value is stored and the measured values are stored and processed as differences with regard to the base value associated with that input transducer.

13. A method according to claim 1, wherein the envelope is conveyed along at least two input transducers in positions mutually spaced transversely to the direction of conveyance, and a particular signal which can be observed by an operator of the apparatus is generated only if envelope-suspect signals have been caused by measuring results originating from at least two immediately adjacent input transducers.

14. A method according to claim 13, wherein the signal observable by the operator is furthermore generated only if the parts of the respective value profiles that lie beyond the limit value, on the ground of which said envelope-suspect signals have been generated, belong to adjacent parts of the measuring path which overlap in the direction of conveyance.

15. A method according to claim 14, wherein the signal observable by the operator is furthermore generated only if said adjacent parts of the measuring path overlap in the direction of conveyance over a predetermined minimum distance.

16. A method according to claim 1, wherein the input transducer scans the thickness of the envelope and the value profile represents a thickness profile of the envelope along the measuring path.

17. A method according to claim 1, wherein the value profile comprises a filtered representation and a less filtered representation, the filtered representation being obtained by calculating a progressive average of the unfiltered representation, the reference value being determined on the basis of the filtered representation and the unfiltered representation being checked for the presence of a part that lies outside the range limited by the limit value and is longer than the predetermined minimum length.

18. An apparatus for separating documents from opened envelopes and for checking whether documents have been separated from the opened envelopes, comprising:

separating means for separating contents from opened envelopes;

a conveyor track for passing opened envelopes to be checked individually from said separating means along an inspection station,

said inspection station including at least one input transducer arranged on the conveyor track for generating an output signal responsive to a characteristic of the envelope material passed along the input transducer, and means for generating an envelope-suspect signal, comprising data processing means, coupled to receive the output signal of the input transducer, for determining a value profile for each individual envelope from the signal originating from the input transducer for the individual envelope, storing said value profile, determining a reference value for the envelope material of the individual envelope from the value profile, determining an extreme limit value from the reference value, and generating an envelope-suspect signal if a continuous part of the value profile for the individual envelope lies beyond the extreme limit value over a predetermined minimum substantially continuous distance.

19. An apparatus according to claim 18, comprising at least two input transducers in positions mutually spaced transversely to the direction of conveyance.

20. An apparatus according to claim 19, comprising an output transducer for generating a particular signal observable by an operator of the apparatus and means for activating the output transducer in reaction to envelope-suspect signals that have been caused by measuring results originating from at least two immediately adjacent input transducers.

21. A method according to claim 19, wherein the positions of the at least two transducers are relatively staggered in the direction of movement of the conveyor.