Optics: measuring and testing – By configuration comparison – With photosensitive film or plate
Patent
1989-04-25
1991-02-12
Evans, F. L.
Optics: measuring and testing
By configuration comparison
With photosensitive film or plate
250560, G01B 1106
Patent
active
049919695
ABSTRACT:
A method for measuring a film thickness of a sheet including feeding a sheet over a rotary shaft, providing a light shield parallel to the center of rotation of the rotary shaft at a predetermined distance from the rotary shaft surface to define a gap therebetween, scanning the gap with a laser beam, and measuring the time during which the laser beam passes through the gap to determine the film thickness of the sheet to be measured. A different-diameter portion is provided at the end portion of the rotary shaft for calculating a difference between the time during which the laser beam passes through the gap on the different-diameter portion and the time during which the laser beam passes through the gap on the portion of the rotary shaft adjacent to the different-diameter portion and on which no sheet is placed, and correcting the time during which the laser beam passes between the surface of the sheet and the light shield by utilizing the calculated difference to obtain the thickness of the sheet.
REFERENCES:
patent: 4311392 (1982-01-01), Yazaki et al.
"Optics and Electronics", No. 99, New Technical Communications, p. 125.
Sensor Technique, vol. 6, No. 2, Feb. 1966.
Ariki Masayuki
Nagao Toshishige
Nakano Hideki
Tokumaru Makoto
Evans F. L.
Mitsubishi Denki & Kabushiki Kaisha
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