Detection device, detection method, and detection system

Abstract

The present invention detects the presence or absence of an internal rear surface structure which cannot be visually observed from the front surface of an object to be measured, and estimates the size of the internal rear surface structure.　This detection device detects an internal rear surface structure including at least one among a hollow portion that can exist inside an object to be measured and a notch portion that can exist in the rear surface of the object to be measured. The detection device comprises: an image acquisition unit that acquires images obtained by imaging the object to be measured before and after deformation; a strain distribution calculation unit that calculates a strain distribution on the front surface of the object to be measured by comparing and analyzing the images obtained by imaging the object to be measured before and after deformation; a strain gradient distribution calculation unit that calculates a strain gradient distribution by differentiating the calculated strain distribution in a distance direction; and an internal rear surface structure detection unit that estimates the size of the internal rear surface structure by analyzing the calculated strain gradient distribution.

Claims

1. A detection device for detecting an internal back surface structure that includes at least one of a hollow portion that may exist inside an object to be measured and a notched portion that may exist on the back surface of the object to be measured, comprising: an image acquisition unit that acquires images of the object to be measured before and after deformation; a strain distribution calculation unit that calculates the strain distribution on the surface of the object to be measured by comparing and analyzing the images of the object to be measured before and after deformation; a strain gradient distribution calculation unit that calculates the strain gradient distribution by differentiating the calculated strain distribution in the distance direction; and an internal back surface structure detection unit that estimates the size of the internal back surface structure by analyzing the calculated strain gradient distribution.

2. A detection device according to claim 1, wherein the internal back surface structure detection unit calculates the distance between extreme values ​​in the strain gradient distribution as an estimated value of the size of the internal back surface structure.

3. A detection device according to claim 1, wherein the internal back surface structure detection unit calculates the size of a region in a monochrome image obtained by binarizing the strain gradient distribution where the pixel value is greater than or equal to a threshold value as an estimate of the size of the internal back surface structure.

4. A detection device according to claim 3, wherein the internal back surface structure detection unit changes the threshold used when binarizing the strain gradient distribution, and calculates the median value of the size of the region that changes in response to the change in the threshold, as an estimate of the size of the internal back surface structure.

5. A detection device according to claim 4, wherein the internal back surface structure detection unit is a detection device for evaluating the reliability of an estimated value of the size of the internal back surface structure.

6. A detection device according to claim 5, comprising a UI control unit that displays an estimated value of the size of the internal back surface structure and at least one of the reliability of the estimated value on a UI screen.

7. A detection device according to claim 5, wherein the internal back surface structure detection unit calculates the median value of the size of the region that changes in response to the change in the threshold when the strain gradient distribution is binarized, as an estimated value of the size of the internal back surface structure, and evaluates that the higher the continuity of the size of the region that changes in response to the change in the threshold, the higher the reliability.

8. A detection device according to claim 7, wherein the internal back surface structure detection unit evaluates the continuity of the size of the region based on the sum of the amount of change in the size of the region that changes in response to a minute change in the threshold.

9. A detection method using a detection device for detecting an internal back surface structure that includes at least one of a hollow portion that may exist inside an object to be measured and a notched portion that may exist on the back surface of the object to be measured, the detection method comprising: an image acquisition step of acquiring images of the object to be measured before and after deformation; a strain distribution calculation step of calculating the strain distribution on the surface of the object to be measured by comparing and analyzing the images of the object to be measured before and after deformation; a strain gradient distribution calculation step of calculating the strain gradient distribution by differentiating the calculated strain distribution in the distance direction; and an internal back surface structure detection step of estimating the size of the internal back surface structure by analyzing the calculated strain gradient distribution.

10. A detection system comprising an imaging device, a detection device, and a terminal device, for detecting an internal back surface structure including at least one of a hollow portion that may exist inside an object to be measured and a notched portion that may exist on the back surface of the object to be measured, wherein the imaging device images the object to be measured before and after deformation, the detection device comprises an image acquisition unit that acquires the image captured by the imaging device, a strain distribution calculation unit that calculates the strain distribution on the surface of the object to be measured by comparing and analyzing the images of the object to be measured before and after deformation, a strain gradient distribution calculation unit that calculates the strain gradient distribution by differentiating the calculated strain distribution in the distance direction, an internal back surface structure detection unit that estimates the size of the internal back surface structure by analyzing the calculated strain gradient distribution, and a UI control unit that causes the terminal device to display a UI screen showing the estimated size of the internal back surface structure, the terminal device being a detection system that displays the UI screen.

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