Web tracking and control

Claim 2

Apparatus for at automatically measuring the amount and direction of sideway displacement of one edge of a continuous and moving web of material, comprising: a source of electric voltage of preselected frequency; a first transducer electrically connected to said source for translating said voltage into sound waves having said voltage frequency, said transducer having a surface of predetermined area for transmitting said sound waves into an ambient environment; a second transducer having a surface oppositely disposed to said first transducer surface and coextensive therewith for receiving said sound waves from said environment and translating said last-mentioned waves into an electric voltage having the frequency of said source voltage; acoustical impedance matching means on said first and second transducer surfaces; said acoustical matching means including a plate having a thickness of the order of an odd number of one-fourth wavelengths of said sound waves in said environment, said plate provided with a plurality of spaced holes extending throUgh said thickness thereof, said plate having a surface substantially coextensive with the associated surface of the transducer on which said plate is mounted; said web having one edge along the width thereof disposed in a preselected position in said environment between said first and second transducer surfaces for attenuating said sound waves a predetermined amount and thereby attenuating the translated voltage a corresponding amount, said one edge of said web further attenuating said sound waves and translated voltage in proportion to the amount and direction of the sideway displacement of said one edge of said web with regard to said preselected position as said web is moved in a lengthwise direction; and means electrically connected to said second transducer for deriving from said attenuated voltage corresponding to said preselected position of said one edge of said web a voltage of predetermined magnitude and for deriving from the further attenuated voltage a voltage varying in magnitude relative to said last-mentioned predetermined voltage magnitude to provide automatic measurements of the amount and direction of said sideway displacement of said one edge of said web relative to said preselected position thereof as said web is moved in said lengthwise direction.

Claim 3

The apparatus according to claim 1 in which each of said plates is mounted a distance of approximately 0.010 inch from said associated transducer surface.

Claim 4

The apparatus according to claim 1 in which said driving means includes in sequence a filter connected to said second transducer and tuned to the frequency of said second transducer translated voltage, an amplifier for amplifying said second transducer translated voltage, a converter for lie linearly changing the translated voltage into a direct voltage, and a meter for indicating the magnitude of the converted direct voltage.

Claim 5

Apparatus for automatically measuring the amount and direction of the sideway displacement of the opposite edges of a continuous and moving web of material, comprising: a source of electrical voltage of predetermined frequency; a first pair of spaced transducers connected to said voltage source and translating said voltage into two discrete streams of sound waves having the voltage predetermined frequency, said transducers having surfaces of predetermined equal areas for transmitting said two sound wave streams into common environments; a second pair of transducers, each associated with one of said first transducers, said second transducers having surfaces spaced from and coextensive with said first transducer surfaces for receiving said sound wave streams from said environments and translating said last-mentioned sound wave streams into two discrete corresponding electric waves having the frequency of said source voltage, acoustical impedance matching means on the surfaces of said first and second pairs of transducers, said acoustical matching means including a plate having a thickness of the order of an odd number of one-fourth wavelengths of said sound waves in said streams in said environments so as to substantially maximize the power transference between associated transducers; said web having the opposite edges along the width thereof disposed in preselected positions in said sound wave streams for attenuating said sound waves therein a predetermined amount and thereby attenuating the associated translated voltages a corresponding amount, said web opposite edges further attenuating said sound waves in said sound streams and associated translated voltages in proportion to the amount and direction of the sideway displacement of said web edges with regard to said preselected positions thereof as said web is moved in a lengthwise direction; and means electrically connected to said second transducers for deriving from said two attenuated voltages corresponding to said preselected positions of said web opposite edges a difference voltage of predetermined magnitude And for additionally deriving from said further attenuated voltages another difference voltage varying in magnitude and polarity relative to said predetermined voltage magnitude difference of the sideway displacement of said web opposite edges with regard to said preselected positions thereof as said web is moving in said lengthwise direction.

Claim 6

Apparatus for automatically measuring the amount and direction of the sideway displacement of the opposite edges of a continuous and moving web of material, comprising: a source of electrical voltage of predetermined frequency; a first pair of spaced transducers connected to said voltage source and translating said voltage into two discrete streams of sound waves having the voltage predetermined frequency, said transducers having surfaces of predetermined equal areas for transmitting said two sound wave streams into common environments; a second pair of transducers, each associated with one of said first transducers, said second transducers having surfaces spaced from and coextensive with said first transducer surfaces for receiving said sound wave streams from said environments and translating said last-mentioned sound wave streams into two discrete corresponding electric waves having the frequency of said source voltage, acoustical impedance matching means on the surfaces of said first and second pairs of transducers, said acoustical matching means including a plate having a thickness of the order of an odd number of one-fourth wavelengths of said sound waves in said streams in said environments so as to substantially maximize the power transference between associated transducers; said web having the opposite edges along the width thereof disposed in preselected positions in said sound wave streams for attenuating said sound waves therein a predetermined amount and thereby attenuating the associated translated voltages a corresponding amount, said web opposite edges further attenuating said sound waves in said sound streams and associated translated voltages in proportion to the amount and direction of the sideway displacement of said web edges with regard to said preselected positions thereof as said web is moved in a lengthwise direction; and means electrically connected to said second transducers for deriving from said two attenuated voltages corresponding to said preselected positions of said web opposite edges a difference voltage of predetermined magnitude And for additionally deriving from said further attenuated voltages another difference voltage varying in magnitude and polarity relative to said predetermined voltage magnitude difference of the sideway displacement of said web opposite edges with regard to said preselected positions thereof as said web is moving in said lengthwise direction.

Claim 7

The apparatus according to claim 2 in which said voltage deriving means comprises: a pair of electrical paths, each providing a voltage of varying magnitude and preselected polarity and including in sequence; a filter connected to each of said second transducers and tuned to the frequency of said second transducer translated voltage; an amplifier for the last-mentioned translated voltages; a converter for translating the amplified translated voltage into direct voltage; a comparator for deriving a difference voltage of varying magnitude from the voltage of varying magnitude and polarity in the respective last-mentioned paths; and a meter for providing indications of said last-mentioned difference voltage of varying magnitude.

Claim 8

Apparatus for automatically measuring the amount and direction of sideway displacement of the opposite edges of a continuous and moving web of material, comprising: means for continuously providing two discrete paths of sound waves; means for continuously receiving said sound waves from said two discrete paths and translating said last-mentioned sound waves in said two paths into two corresponding discrete electric voltages; said web having the opposite edges along the width thereof disposed at preselected positions in said two sound wave paths for attenuating the sound waves therein a predetermined amount and thereby attenuating the associated translated voltage a corresponding amount, said web edges further attenuating said sound waves in said two paths and said attenuated two associated voltages in proportion to the amount and direction of the sideway displacement of said web edges with regard to said preselected positions thereof as said web is moved in a lengthwise direction; and means connected to said receiving means for deriving from said attenuated two voltages corresponding to said preselected positions of said web opposite edges a difference voltage of predetermined magnitude and for additionally deriving from the further attenuates two voltages a difference voltage whose absolute magnitude indicates the amount and direction of the sideway displacement of said web opposite edges with regard to said preselected positions thereof as said web is moving in said lengthwise direction.

Claim 9

Apparatus for automatically measuring the amount and direction of sideway displacement of the opposite edges of a continuous and moving web of material, comprising: means for continuously providing two discrete paths of sound waves; means for continuously receiving said sound waves from said two discrete paths and translating said last-mentioned sound waves in said two paths into two corresponding discrete electric voltages; said web having the opposite edges along the width thereof disposed at preselected positions in said two sound wave paths for attenuating the sound waves therein a predetermined amount and thereby attenuating the associated translated voltage a corresponding amount, said web edges further attenuating said sound waves in said two paths and said attenuated two associated voltages in proportion to the amount and direction of the sideway displacement of said web edges with regard to said preselected positions thereof as said web is moved in a lengthwise direction; and means connected to said receiving means for deriving from said attenuated two voltages corresponding to said preselected positions of said web opposite edges a difference voltage of predetermined magnitude and for additionally deriving from the further attenuates two voltages a difference voltage whose absolute magnitude indicates the amount and direction of the sideway displacement of said web opposite edges with regard to said preselected positions thereof as said web is moving in said lengthwise direction.

Claim 10

The apparatus according to claim 6 in which each of said plates is mounted a distance of approximately 0.010 inch from said associated transducer surface.

Claim 11

Apparatus for automatically measuring the amount and direction of the sideway displacement of the opposite edges of a continuous and moving web of material, comprising: a source of electrical voltage of predetermined frequency; a first pair of spaced transducers connected to said voltage source and translating said voltage into two discrete streams of sound waves having the voltage predetermined frequency, said transducers having surfaces of predetermined equal areas for transmitting said two sound wave streams into common environments; a second pair of transducers, each associated with one of said first transducers, said second transducers having surfaces spaced from and coextensive with said first transducer surfaces for receiving said sound wave streams from said environment and translating said last-mentioned sound wave streams into two discrete corresponding electric waves having the frequency of said source voltage; acoustical impedance matching means on the surface of each of said first and second transducers, said acoustical matching means, including a plate having a thickness of the order of an odd number of one-fourth wavelengths of said sound waves in said streams in Said environments and provided with a plurality of spaced holes extending through said thickness thereof, said plate having a surface substantially coextensive with the associated transducer surface and spaced a predetermined distance therefrom, said last-mentioned distance comprising a gap of said environment; said web having the opposite edges along the width thereof disposed in preselected positions in said sound wave streams for attenuating said sound waves therein a predetermined amount and thereby attenuating the associated translated voltages a corresponding amount, said web opposite edges further attenuating said sound waves in said sound streams and associated translated voltages in proportion to the amount and direction of the sideway displacement of said web edges with regard to said preselected positions thereof as said web is moved in a lengthwise direction; and means electrically connected to said second transducers for deriving from said two attenuated voltages corresponding to said preselected positions of said web opposite edges a difference voltage of predetermined magnitude and for additionally deriving from said further attenuated voltages another difference voltage varying in magnitude and polarity relative to said predetermined voltage magnitude difference of the sideway displacement of said web opposite edges with regard to said preselected positions thereof as said web is moving in said lengthwise direction.

Claim 12

Apparatus for automatically measuring the amount and direction of the sideway displacement of the opposite edges of a continuous and moving web of material, comprising: a source of electrical voltage of predetermined frequency; a first pair of spaced transducers connected to said voltage source and translating said voltage into two discrete streams of sound waves having the voltage predetermined frequency, said transducers having surfaces of predetermined equal areas for transmitting said two sound wave streams into common environments; a second pair of transducers, each associated with one of said first transducers, said second transducers having surfaces spaced from and coextensive with said first transducer surfaces for receiving said sound wave streams from said environment and translating said last-mentioned sound wave streams into two discrete corresponding electric waves having the frequency of said source voltage; acoustical impedance matching means on the surface of each of said first and second transducers, said acoustical matching means, including a plate having a thickness of the order of an odd number of one-fourth wavelengths of said sound waves in said streams in Said environments and provided with a plurality of spaced holes extending through said thickness thereof, said plate having a surface substantially coextensive with the associated transducer surface and spaced a predetermined distance therefrom, said last-mentioned distance comprising a gap of said environment; said web having the opposite edges along the width thereof disposed in preselected positions in said sound wave streams for attenuating said sound waves therein a predetermined amount and thereby attenuating the associated translated voltages a corresponding amount, said web opposite edges further attenuating said sound waves in said sound streams and associated translated voltages in proportion to the amount and direction of the sideway displacement of said web edges with regard to said preselected positions thereof as said web is moved in a lengthwise direction; and means electrically connected to said second transducers for deriving from said two attenuated voltages corresponding to said preselected positions of said web opposite edges a difference voltage of predetermined magnitude and for additionally deriving from said further attenuated voltages another difference voltage varying in magnitude and polarity relative to said predetermined voltage magnitude difference of the sideway displacement of said web opposite edges with regard to said preselected positions thereof as said web is moving in said lengthwise direction.