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Measuring method and measuring device

  • US 9,704,237 B2
  • Filed: 10/10/2013
  • Issued: 07/11/2017
  • Est. Priority Date: 11/29/2012
  • Status: Active Grant
First Claim
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1. A measuring method for measuring a surface form of a measurement surface, the measurement surface being a tread surface or a sidewall surface of a tire having a projection formed thereon, the method comprising:

  • a first measuring step of performing a measurement process a plurality of times while shifting a spotlight emitted from a spot light source in a sub-scanning direction on a reference tire, and acquiring a plurality of pieces of measurement data, the measurement process including illuminating the measurement surface with the spotlight, scanning the measurement surface in a main-scanning direction with the spotlight, receiving reflected light, and acquiring measurement data for one line;

    a first acquisition step of generating pieces of one-dimensional height data respectively from the plurality of pieces of measurement data, arranging the plurality of generated pieces of one-dimensional height data in a matrix, and generating two-dimensional height data of the measurement surface;

    a step of generating reference form data of the reference tire by;

    extracting a boundary of the projection from the two-dimensional height data using an edge detection filter;

    extracting a region surrounded by the extracted boundary as the projection; and

    associating a position of the extracted projection with the two-dimensional height data;

    a second measuring step of performing the measurement process on the measurement surface of a target tire, which is a measurement object, and acquiring the measurement data for one line;

    a second acquisition step of generating one-dimensional height data using the measurement data acquired in the second measuring step; and

    a removal step of comparing target one-dimensional height data, which is the one-dimensional height data acquired in the second acquisition step, with one-dimensional height data in the reference form data, a corresponding position of which in the sub-scanning direction is the same as the target one-dimensional height data, and removing a height component of the projection from the target one-dimensional height data, whereinin the step of generating the reference form data, an average or a median of height data at each position in a background region other than the projection is calculated as a reference value of the background region from height data at each position of the two-dimensional height data, a height component at each position in the projection is generated by subtracting the reference value from height data at each position in the projection, and the generated height component is associated with the two-dimensional height data, andin the removal step, a region of the projection in the target one-dimensional height data is identified using one-dimensional height data in the reference form data, a corresponding position of which in the sub-scanning direction is the same as the target one-dimensional height data, and the height component is subtracted from the height data at each position in the identified region of the projection to thereby exclude the projection from the target one-dimensional height data.

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