Unevenness measuring device for sheet-shaped material, and unevenness measuring method for sheet-shaped material

An unevenness measuring device for a sheet-shaped material for measuring a depth of a local recessed portion and/or a height of a local projecting portion of a sheet-shaped material being conveyed, using a surface of the sheet-shaped material held on a roller as a measurement target, the device comprising:

• a light irradiation unit configured to irradiate the measurement target with illumination light such that the illumination light is partially blocked at the measurement target, the measurement target being a surface on an opposite side to a portion that is in contact with the roller in the sheet-shaped material held on the roller;
• a time-delay integration type imaging unit arranged to face the light irradiation unit and configured to receive the illumination light that is irradiated from the light irradiation unit and that is not blocked at the measurement target;
• a luminance-profile calculation unit configured to calculate a luminance profile in a main-scanning direction from a captured image generated by the imaging unit;
• an unevenness determination unit configured to determine, based on the luminance profile, whether the sheet-shaped material has a recessed portion and/or a projecting portion;
• and
• an unevenness calculation unit configured to estimate, based on the luminance profile, a depth of the recessed portion and/or a height of the projecting portion.