Combined ultrasonic-based multifeed detection system and sound-based damage detection system

1. A sheet handling apparatus comprising:

a transport path;

a device adapted to separate a first sheet from a plurality of stacked sheets and to feed the first sheet into the transport path;

only one detector positioned near the transport path to detect a signal indicative of a multifeed condition indicating that a second sheet is overlapping the first sheet and a signal indicative of a misfeed condition indicating that the first sheet is being damaged in the transport path; and

a processing system coupled to the detector, adapted to receive and process signals from the detector and to filter the audio signals into separate first and second frequency bands for separate processing, wherein the first frequency band is used to determine the multifeed condition and the second frequency band is used to determine the misfeed condition, the processing system configured to determine either a multifeed in the transport path or a misfeed in the transport path and to terminate feeding sheets in response to the determination.

2. The apparatus according to claim 1 , wherein the detector comprises an ultrasonic energy source.

3. The apparatus according to claim 2 , wherein the detector further comprises a microphone.

4. The apparatus according to claim 3 , wherein the detector further comprises a mount made from a compliant noise isolating material.

5. The apparatus of claim 1 , further comprising a filter for separating the signals into two frequency bands.

6. The apparatus of claim 1 , wherein the processor is further configured to calculate an energy level of the digital audio data in the second frequency band to determine the misfeed.

7. The apparatus of claim 1 , wherein the processing system further comprises a converter for converting the signals from the detector into the digital data.

8. An article processing apparatus for processing a plurality of articles, comprising:

a transport path for the plurality of articles;

a feeder device for feeding individual ones of the articles into the transport path;

only one audio detector positioned in the transport path to detect signals indicative of a multifeed condition in the transport path and a misfeed condition in the transport path; and

a processing system coupled to the detector to receive and process signals from the detector and to filter the signals into separate first and second frequency bands for separate processing, wherein the first frequency band is used to determine the multifeed condition and the second frequency band is used to determine the misfeed condition, the processing system configured to terminate processing the plurality of articles in response to the signals from the detector.

9. The apparatus according to claim 8 , wherein the detector comprises an ultrasonic device and a microphone.

10. The apparatus according to claim 8 , further comprising a converter coupled to the detector for converting the signals from the detector into digital data frames which are received by the processing system.

11. The apparatus of claim 10 , wherein the processing system for calculates an energy level of the data frames to determine if the data frames indicate the misfeed condition.

12. The apparatus according to claim 11 , wherein the processing system counts a number of data frames that indicate the misfeed condition.

13. The apparatus of claim 12 , wherein the processing system issues a termination signal in response to the number of data frames that indicate the misfeed condition exceeding a preselected number.

14. A document handling apparatus comprising:

a document transport path for moving the document therethrough;

only one detector proximate the transport path for detecting a signal indicating a multifeed in the transport path and for detecting a signal indicating a misfeed in the transport path; and

a processing system coupled to the detector for processing the signal indicating multifeed and the signal indicating misfeed, for filtering the signal indicating multifeed and the signal indicating misfeed into separate frequency bands for separate processing, and for issuing a termination signal terminating document handling by the apparatus in response to determining a multifeed or a misfeed or both.

15. The apparatus according to claim 14 , wherein the detector comprises a microphone, the signal indicating multifeed comprises ultrasonic sound, and the signal indicating misfeed comprises sound emanating from the document being damaged.

16. The apparatus according to claim 15 , wherein the processing system includes a converter coupled to the detector for converting the signal indicating misfeed into digital data frames.

17. The apparatus according to claim 16 , wherein the processing system comprises a processor for analyzing the digital data frames and determining whether the document is undergoing the misfeed.