Sensor position independent material property determination using radiant energy

A radiant energy method for determining a property of a sheet material that is normally inspected while traveling generally along a nominal sheet path, comprising

• utilizing a sensor means to respond to a condition of the sheet material and to produce a sensor response that can be related to the material property, the relation of the sensor response to the property being susceptible to change with changes in the distance relationship of the sensor means and the sheet material,
• supporting and guiding the sensor means generally along at least one nominal sensor path transverse to the sheet path so as to permit sensing the sheet condition at a plurality of locations spaced across the width of the sheet, the actual path or paths of the sensor means being subject to deviations from the nominal path that may result in changes in the distance from the sensor means to the sheet material and thereby adversely influence the sensor response,
• defining a reference path that is relatively independent of at least one factor that tends to produce a deviation of the actual path or paths of the sensor means,
• producing a distance response to changes in the distance from the sensor means to the reference path, and
• systematically relating the sensor response to the distance response so as to produce a sheet property response with substantially decreased susceptibility to change with the changes in the distance relationship of the sensor means and the material.

Radiant energy apparatus for determining a property of a material that is normally inspected while located generally in a predetermined spatial relation to a first reference position, comprising

• means for defining a second reference position,
• sensor means responsive to a condition of the material for producing a sensor response that can be related to the material property, the relation of the sensor response to the property being susceptible to change with changes in the distance relationship of the sensor means and one of the reference positions or the material,
• means for producing a distance response to changes in the distance from the sensor means to at least one of the reference positions,
• means for producing an initial sensor and distance response-related value or values that can be derived by utilizing the first and second reference positions, and
• means responsive to the distance response, the initial value or values, and the sensor response for producing a material property response with substantially decreased susceptibility to change with the changes in the distance relationship of the sensor means and the reference position or the material.

Radiant energy apparatus for determing a property of a sheeet material that is normally inspected while traveling generally along a nominal sheet path, comprising

• sensor means responsive to a condition of the sheet material for producing a sensor response that can be related to the material property, the relation of the sensor response to the property being susceptible to change with changes in the distance relationship of the sensor means and the sheet material,
• means for supporting and guiding the sensor means generally along at least one nominal sensor path transverse to the sheet path so as to permit sensing the sheet condition at a plurality of locations spaced across the width of the sheet, the actual path or paths of the sensor means being subject to deviations from the nominal path that may result in changes in the distance from the sensor means to the sheet material and thereby adversely influence the sensor response,
• means defining a reference path that is relatively independent of at least one factor that tends to produce a deviation of the actual path or paths of the sensor means,
• means for producing a distance response to changes in the distance from the sensor means to the reference path, and
• means for systematically relating the sensor response to the distance response so as to produce a sheet property response with substantially decreased susceptibility to change with the changes in the distance relationship of the sensor means and the material.