Patent ID: 11927435
Assignee: CKD CORPORATION
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 2:
3. A three-dimensional measurement device that performs three-dimensional measurement of a measured object using a phase shift method, the three-dimensional measurement device comprising:
a first irradiator that irradiates the measured object with a first light pattern having a light intensity distribution in a fringe shape;
a second irradiator that irradiates the measured object with a second light pattern having a light intensity distribution in a fringe shape;
a control device that:
shifts a phase of the first light pattern radiated from the first irradiator in N different ways, where N is a natural number of not less than 3, and
shifts a phase of the second light pattern radiated from the second irradiator in N different ways, where N is a natural number of not less than 3; and

an imaging device that takes an image of the measured object irradiated with the first light pattern or with the second light pattern, wherein
the control device executes three-dimensional measurement of the measured object based on image data obtained by the imaging device,
the control device executes the three-dimensional measurement by:
executing first height measurement based on N different image data taken under the first light pattern having the phase shifted in the N different ways,
executing second height measurement based on N different image data taken under the second light pattern having the phase shifted in the N different ways,
calculating height measurement data of the measured object based on a measurement result of the first height measurement and a measurement result of the second height measurement,
the control device executes the first height measurement and the second height measurement by:
obtaining N luminance values with respect to a predetermined coordinate position on the image data based on the N different image data;
extracting luminance values of not less than two but less than N from among the N luminance values, wherein the extracted luminance values are neither overexposed nor underexposed; and
executing height measurement at the predetermined coordinate position based on the luminance values of not less than two but less than N, and

the control device calculates the height measurement data by:
when there is a difference between first and second numbers of the luminance values, wherein the first number is a number of luminance values that are neither overexposed nor underexposed and used for calculation of the first height measurement, and the second number is a number of luminance values that are neither overexposed nor underexposed and used for calculation of the second height measurement,
obtaining, as the height measurement data, the measurement result based on the larger number of luminance values among the first and second numbers, or
obtaining, as the height measurement data, a result of weighting of the measurement result based on the larger number of luminance values by a predetermined weight.