Patent ID: 7259873

Claim:
A method for measurement of dimensions of an elongated article in a measuring plane perpendicular to the article, the article having a cross-section, the cross-section having a circumference, the article having a longitudinal axis and a non-circular cross-section, the circumference of the cross-section of the article, respectively having sections which are circular and elliptical, the circular cross-section having a centre and a radius, the elliptical cross-section having a centre and a large and a small radii, the measurement taking place along at least an axis of the cross-section, the method comprising the following steps: the article is illuminated in the measuring plane approximately perpendicular to the longitudinal axis by spaced light sources, the light sources being stationary with respect to the article, the number and the position of the light sources being such that per circular section at least three different peripheral rays and per elliptical section at least four different peripheral rays are generated; the peripheral rays impinge at least one light sensitive, position resolving sensor; coordinates of the position of the light sources and of at least one light sensor in a coordinate system in the measuring plane are stored in a memory of a measuring device; the coordinates of the position on the sensor where the rays impinge the sensor are determined; position data of the centres of the circular and elliptical sections and data of the radius of the circular sections and of the large and the small radii of the elliptical sections are calculated from the coordinates of the impinging positions and of the light sources using geometrical equations; at least one dimension of the cross-section of the article is determined from the calculated data; at least one of the determined dimensions is stored in the memory of the measuring device; and using the determined dimensions in an electronic control to control the dimensions of the article.