Acoustic flute web edge sensor

An acoustic web edge sensor comprising:

• a) a body having a surface over which a web having an edge is movable;
• b) an acoustic pipe comprising a fluid conducting region of determinate length in said body, said pipe being closed at each end and having an opening between said ends for placing said region in fluid communication with said surface;
• c) said web being located on said surface with said edge in said opening and said web initially covering a portion of said opening;
• and
• d) acoustic transmitting/receiving means operatively connected to said acoustic pipe for sending acoustic energy along said pipe and for receiving reflected acoustic energy in said pipe;
• e) so that as said web moves along said surface in a direction changing the portion of said opening covered by said web an acoustic signal is produced which contains information as to the location of said edge of said web.

A web width sensor comprising:

• a) a first acoustic flute web edge sensor for providing an acoustic signal indicative of the location of one edge of a web;
• b) a second acoustic flute web edge sensor for providing an acoustic signal indicative of the location of the other edge of the web;
• and
• c) so that by locating the positions of both edges of the web the width of the web is determined.

An acoustic web width sensor comprising:

• a) a body having a surface over which a web having a pair of edges is movable;
• b) a first acoustic pipe comprising a fluid conducting region of determinate length in said body, said pipe being closed at each end and having an opening between said ends for placing said region in fluid communication with said surface;
• c) said web being located on said surface with one of said edges in said opening and said web initially covering a portion of said opening;
• d) first acoustic transmitting/receiving means operatively connected to said acoustic pipe for sending acoustic energy along said pipe and for receiving reflected acoustic energy in said pipe;
• e) a second acoustic pipe comprising a fluid conducting region of determinate length in said body, said pipe being closed at each end and having an opening between said ends for placing said region in fluid communication with said surface;
• f) said web being located on said surface with the other of said edges in said opening of said second acoustic pipe and said web initially covering a portion of said opening;
• and
• g) second acoustic transmitting/receiving means operatively connected to said second acoustic pipe for sending acoustic energy along said pipe and for receiving reflected acoustic energy in said pipe;
• h) so that as said web moves along said surface in a direction changing the portions of said openings covered by said web acoustic signals are produced which contain information as to the location of said edges of said web thereby determining the width of said web.

A method for sensing the edge of a web comprising the steps of:

• a) providing an acoustic pipe in a body having a surface contacted by said web, said pipe having an opening located so that the edge of the web covers a portion of the opening as a function of the position of the web;
• b) causing an air column in said pipe to resonate so that the resultant acoustic signal has a resonant frequency spectrum which is a function of the portion of the opening which is covered by the web;
• and
• c) utilizing the resultant acoustic signal to provide information relating to the location of said edge of said web.

A method for sensing the width of a web comprising the steps of:

• a) providing a first acoustic flute web edge sensor in operative association with one of the edges of the web to produce an acoustic signal indicative of the location of said one edge;
• b) providing a second acoustic flute web edge sensor in operative association with the other edge of the web to produce an acoustic signal indicative of the location of said other edge;
• and
• c) utilizing the resultant acoustic signals to provide information as to the locations of the edges of the web thereby determining the width of the web.