Method and apparatus for detection of wrinkled documents in a sheet feeding device

A method for detecting wrinkling of sheets of material, comprising:

• a) transporting the sheet of material along a feed path;
• b) arranging a transmitter at a predetermined angle to the feed path;
• c) sending a signal from the transmitter through the feed path and the sheet as it passes the transmitter;
• d) detecting changes in an angle of a paper with respect to the signal;
• e) determining the sheet is wrinkling based on the changes in the angle;
• wherein step d) comprises:
• receiving the signal after is passes through the sheet;
• comparing a amplitude of the received signal with an amplitude of the transmitted signal;
• and
• determining the change in the angle based on the comparison of the amplitudes.

In a document transport system that transports a document along a feed path, a method of detecting document jams, the method comprising:

• determining a desired angle the document forms with the feed path during normal operation;
• detecting an actual angle the document forms with the feed path;
• determining a difference between the desired angle and the actual angle;
• a document jam when the difference exceeds a predetermined threshold;
• impinging an ultrasonic signal on the document;
• receiving a portion of the impinged signal after it passes through the document;
• determining at least one of a phase difference and an amplitude difference between the impinged signal and the impinged signal after it passes through the document;
• and
• determining if the document is wrinkled based on at least one of the phase difference and the amplitude difference.

A method of detecting wrinkling of sheets of material, comprising:

• a) transmitting a signal through the sheet;
• b) receiving the signal after it has passed through the sheet;
• c) comparing the generated signal to the received signal;
• and
• d) detecting wrinkling in the sheet based on the comparison.

In a mechanism for feeding sheets of material, a method for detecting wrinkling of the sheets, comprising:

• feeding a sheet with the mechanism along a feed path;
• transmitting a signal through the sheet as it passes along the feed path;
• receiving the signal after it passes through the sheet;
• detecting a phase difference between the transmitted signal and the received signal;
• detecting an amplitude difference between the transmitted signal and the received signal;
• determining if the sheet is wrinkling based on at least one of the phase difference and the amplitude difference;
• and
• halting the feeding of the sheet if it is determined the sheet is wrinkling.

A method of detecting wrinkling of sheets, comprising:

• producing a first electrical signal;
• producing an ultrasonic signal that impinges on the sheet at a position along a feed path;
• receiving a portion of the ultrasonic signal that impinged upon the sheet;
• producing a second electrical signal in response to receiving the ultrasonic signal;
• comparing the first and second electrical signals;
• and
• analyzing the first and second electrical signals to determine if the sheet is wrinkled.

An apparatus for detecting wrinkling documents, comprising:

• an ultrasonic transmitter for transmitting a signal;
• an ultrasonic receiver receiving the signal;
• a phase comparator for comparing the transmitted signal and the received signal;
• an amplitude measurement circuit for comparing the transmitted signal and the received signal;
• and
• a microprocessor communicating with the phase comparator and the amplitude measurement circuit to determine if the document is wrinkled.