Flaw detecting method and apparatus

Claim 2

In a material monitoring apparatus for determining the quality of a sheet material, an assembly including housing means and support means connected with said housing means for supporting the same closely adjacent to a surface of a travelling sheet of material without any optical structure between said housing means and said sheet, said housing means being formed with a series of apertures which are arranged in a row extending in the direction of sheet travel with said apertures being of progressively larger sizes in the direction of sheet travel and being directed toward the sheet, a plurality of photoelectric sensing means carried by said housing means for receiving light respectively entering through said apertures thereof directly from the sheet while travelling only through a relatively small air gap between the sheet and the housing means closely adjacent thereto, the amount of light received being dependent upon the quality of the sheet material, traversing means operatively connected with said assembly for moving the latter cyclically first in one direction and then in an opposite direction transversely across the sheet while the latter travels longitudinally, electronic circuit means electrically connected with said plurality of sensing means for converting the light received thereby into electrical signals, and indicating means electrically connected with said electronic circuit means for responding to the electrical signals for indicating the quality of the material.

Claim 3

The combination of claim 1 and wherein each of said photoelectric sensing means includes a retroreflective fiber optical structure having an input end, and output end, and a sensing end, said structure receiving light at said input end and transmitting the light to said sensing end to be directed therefrom to and reflected back from the sheet, said sensing end receiving the reflected light and transmitting it to said output end.

Claim 4

The combination of claim 1 and further comprising spring means interconnecting in cantilever fashion said housing means and said support means.

Claim 5

The combination of claim 1 and wherein said circuit means includes threshold detection means associated with each of said photoelectric sensing means and wherein each of said threshold detection means is set at an effectively higher threshold value corresponding to the progressively larger sized apertures such that a larger sized flaw is required in order to produce an electrical signal from the photoelectric sensing means associated with a larger sized aperture.

Claim 6

The combination of claim 1 and further comprising illuminating means located on the side of the sheet material opposite to the side where said housing is positioned, whereby said photoelectric sensing means senses the light transmitted through the sheet material.

Claim 7

The combination of claim 1 and further comprising sheet guide means for guiding the sheet material to travel along a path adjacent said housing means.

Claim 8

The combination of claim 1 and wherein said circuit means includes weighting circuitry to weigh appropriately the output of each electrical signal in accordance with the size of the corresponding aperture.

Claim 9

The combination of claim 1 and wherein each of said photoelectric sensing means comprises means for receiving light travelling from the sheet through an aperture and photodetector means positioned for receiving the light.

Claim 10

The combination of claim 8 and wherein said electronic circuit means includes amplifier means receiving an output signal from said photodetector means, threshold detection means for receiving the amplified output signal and for producing individual signals corresponding to values of the amplified output signal which are greater than the threshold, means receiving the individual signals from said threshold detection means and producing fixed trigger pulses corresponding to each individual signal, and trigger means receiving said trigger pulses and for producing a pulse of fixed duration in response to each such trigger pulse.

Claim 11

The combination of claim 9 and wherein said indicating means includes digital counter means receiving said fixed duration pulses for counting them.

Claim 12

In a material monitoring apparatus for determining the quality of a sheet material, an assembly including housing means and support means connected with said housing means for supporting the same adjacent a surface of a travelling sheet of material, said housing means being formed with a series of apertures directed toward the sheet and respectively having different sizes, a plurality of photoelectric sensing means carried by said housing means for receiving light respectively entering through said apertures thereof, the amount of light received being dependent upon the quality of the sheet material, electronic circuit means electrically connected with said plurality of sensing means for converting the light received thereby into electrical signals, indicating means electrically connected with said electronic circuit means for responding to the electrical signals for indicating the quality of the material, and an air-bearing means operatively connected with the said assembly for supporting the latter on air over the travelling sheet, said housing means including an outer casing having an open end adjacent said sheet material and an inner container supported within said outer casing and defining an air chamber therewith, said photoelectric sensing means being situated within said inner container, and nozzle means coupled to said air chamber for directing air from said nozzle means through said air chamber to escape from the bottom of said outer casing thereby forming said air bearing means between said housing means and the sheet material.

Claim 13

In a material monitoring apparatus for determining the quality of a sheet material, an assembly including housing means and support means connected with said housing means for supporting the same adjacent a surface of a travelling sheet of material, said housing means being formed with a series of apertures directed toward the sheet and respectively having different sizes, a plurality of photoelectric sensing means carried by said housing means for receiving light respectively entering through said apertures thereof, the amount of light received being dependent upon the quality of the sheet material, electronic circuit means electrically connected with said plurality of sensing means for converting the light received thereby into electrical signals, indicating means electrically connected with said electronic circuit means for responding to the electrical signals for indicating the quality of the material, and an air-bearing means operatively connected with the said assembly for supporting the latter on air over the travelling sheet, said housing means including an outer casing having an open end adjacent said sheet material and an inner container supported within said outer casing and defining an air chamber therewith, said photoelectric sensing means being situated within said inner container, and nozzle means coupled to said air chamber for directing air from said nozzle means through said air chamber to escape from the bottom of said outer casing thereby forming said air bearing means between said housing means and the sheet material.

Claim 16

The method of claim 12 and wherein a warning is automatically given when the indicated quality is poorer than a predetermined lowest quality limit.