Tire shape inspection method and tire shape inspection device

A tire shape inspection apparatus for irradiating a sidewall surface of a relatively rotating tire with line light, the sidewall surface including embossed marks formed therein, picking up an image of the line light, and deriving, based on the picked-up image, surface height distribution information that is used in shape defection inspection of the tire, the apparatus comprising:

• a line light irradiation unit for emitting plural beams of line light in succession, in order to form one optical cutting line on the sidewall surface, from directions differing from a direction of detection height for the optical cutting line;
• an image pickup unit for picking up images of the plural beams of line light, emitted for irradiation of the sidewall surface, in a direction in which a principal ray in each of the plural beams of line light is regularly reflected by the sidewall surface;
• an optical-cutting-method shape detection unit for deriving the surface height distribution information over an entire circumferential range of the sidewall surface by detecting the optical cutting line in the image picked up by the image pickup unit;
• a mask-range automatically setting unit for automatically detecting a position of the embossed mark based on sample surface shape information that is given as the surface height distribution information obtained from a sample of the tire for each type of the tire to be inspected, and automatically setting coordinate information of a mask range surrounding a range where the embossed mark exists;
• an image outputting unit for displaying a surface shape image, which is based on the sample surface shape information, and a mask range image, which is based on the coordinate information of the mask range, on a display unit in a superimposed relation;
• a mask range changing unit for changing, in parallel to processing executed by the image outputting unit, the coordinate information of the mask range in accordance with a predetermined operation input entered through an operating unit;
• an information registration unit for storing, in a storage unit, both the coordinate information of the mask range after being changed by the mask range changing unit, and registered surface shape information that is part or the whole of the sample surface shape information;
• a coordinate-system deviation detection unit for checking inspection-use surface shape information, which is given as the surface height distribution information obtained for each tire to be inspected, with the registered surface shape information, and detecting a deviation of a coordinate system between the inspection-use surface shape information and the coordinate information of the mask range;
• and
• a mask-range inspection exclusion unit for, after correcting the deviation of the coordinate system, excluding those surface height measurement values, which are included in the inspection-use surface shape information and which correspond to the coordinate information of the mask range, from a target of a shape defect inspection process.

A tire shape inspection method for executing a process of inspecting a shape defect in a sidewall surface of a tire in which embossed marks are formed, the shape defect inspection process being executed based on surface height distribution information that is prepared by plotting surface height measurement values at various positions over an entire circumferential range of the sidewall surface in a two-dimensional coordinate system, which has a first coordinate axis representing a radial direction of the tire and a second coordinate axis representing a circumferential direction of the tire,

• the tire shape inspection method comprising:
• a two-dimensional edge detection step of detecting edges of the embossed marks with a two-dimensional edge detection process executed on the surface height distribution information, and storing detected two-dimensional edge distribution information in a storage unit;
• a labeling step of executing labeling on the two-dimensional edge distribution information, and storing label distribution information obtained with the labeling in the storage unit;
• a mask range setting step of setting coordinates of the mask range, which surrounds a range where the embossed mark exists, based on filet coordinates for each label value in the label distribution information, and storing the set coordinates in the storage unit;
• and
• a mask-range interpolation step of replacing those surface height measurement values, which are included in the surface height distribution information used in the shape defect inspection process and which fall within the mask range, with values interpolated based on those surface height measurement values falling outside the aforesaid range.

A tire shape inspection apparatus for irradiating a sidewall surface of a relatively rotating tire with line light, the sidewall surface including embossed marks formed therein, picking up an image of the line light, and deriving, based on the picked-up image, surface height distribution information that is used in shape defection inspection of the tire, the apparatus comprising:

• a line light irradiation unit for emitting plural beams of line light in succession, in order to form one optical cutting line on the sidewall surface, from directions differing from a direction of detection height for the optical cutting line;
• an image pickup unit for picking up images of the plural beams of line light, emitted for irradiation of the sidewall surface, in a direction in which a principal ray in each of the plural beams of line light is regularly reflected by the sidewall surface;
• an optical-cutting-method shape detection unit for deriving the surface height distribution information over an entire circumferential range of the sidewall surface by detecting the optical cutting line in the image picked up by the image pickup unit;
• and
• an embossed mark exclusion unit for excluding information of a range, in which the embossed mark exists, from the surface height distribution information used in the shape defect inspection of the tire for each type of the tire based on the two-dimensional edge detection process that is executed on the surface height distribution information.