JPH09175457A - Distortion inspection method and distortion inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the distortion inspection device with which both a plane mirror and a curved surface mirror can be inspected, and concurrently peripheral parts can be inspected in detail. SOLUTION: An image processing device allows a lattice pattern 18 formed over a projection panel 17 to be projected to a mirror M acting as an inspection object, and image data for the lattice pattern 18 reflected by the mirror M is taken in by a camera 13 to be horizontally moved by a slider 14. Based on the aforesaid image data of the quantity DMH of the maximum diagonal line distortion of each lattice, the quantity AMH of the maximum angular distortion and the number of the lattices, are operated by the image processing device, so that the distortion of the mirror M is thereby detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distortion inspection method and a distortion inspection apparatus, and more particularly to an inspection method and an inspection apparatus for detecting distortion of a reflecting surface such as a mirror.

[0002]

2. Description of the Related Art Conventionally, as a method of measuring optical distortion (distortion of a reflection image) in a reflecting mirror, a distortion test of a reflection image of a mirror material (JIS R 3220), a distortion rate test of an automobile mirror (JIS D5705) Stipulated in.

In the distortion test of the reflection image, a light beam from the projector is applied to the surface of the specimen from a direction of 45 °, and a parallel image is drawn on a seed plate in the projector on a projection surface provided on the reflection optical path. This is a method of projecting straight black and white stripes and measuring the stripe spacing of the projection. Therefore, in this method, the test can be performed only on the flat plate as the mirror material, and the distortion of the curved mirror cannot be detected.

On the other hand, in the distortion rate test, an image of concentric circles at predetermined intervals and an image of eight equidistant lines passing through the center is projected on the mirror surface, and the image of the concentric circles on the mirror surface is taken by a camera or the like. Then, the distortion rate is calculated based on the average radius of the reflection image of the concentric circles and the maximum or minimum radius of the reflection image. According to this method, since the concentric circle scale is used, the plane mirror and the curved mirror can be inspected.

[0005]

However, in the above strain rate test, the average radius of the reflection image of the concentric circles and the radius of the maximum or minimum reflection image are measured, and the interval between the intersections of the concentric circles and the eight equidistant lines is measured. By asking. Therefore, since only the displacement in the radiation direction is detected, the detection accuracy may differ depending on the direction of the distortion. In addition, in the peripheral portion, the interval between the eight equidistant lines (interval in the circumferential direction) becomes wider in the peripheral portion than in the central portion, so that the inspection density becomes coarse, and the strain between the eight equidistant lines cannot be detected. There is.

The present invention has been made in order to solve the above problems, and an object thereof is a strain inspection capable of inspecting a plane mirror and a curved mirror and performing a fine inspection in a peripheral portion. A method and a strain inspection apparatus are provided.

[0007]

In order to solve the above problems, the invention described in claim 1 is a distortion inspection method for detecting distortion of the inspection object based on a reflection image from the inspection object, A grid pattern composed of a plurality of grids is projected onto the inspection object, the distortion amount of each grating of the reflection grating pattern reflected by the inspection object is calculated, and the pass / fail of the inspection object is inspected based on the distortion amount. The main point is to do so.

According to a second aspect of the present invention, in the strain inspection method according to the first aspect, as the strain amount of each of the lattices, the diagonal strain amount based on the diagonal difference of the lattice, each side of the lattice, and the lattice pattern. The gist is that the amount of angular distortion based on the angular difference from the axis of is calculated.

According to a third aspect of the present invention, in the strain inspection method according to the second aspect, the amount of diagonal distortion of the lattice is calculated based on the deviation between the calculated diagonal difference of the lattice and the diagonal difference of surrounding lattices. The gist is that the angular strain amount of the lattice is calculated based on the deviation between the calculated angular difference of the lattice and the angle difference of the surrounding lattices.

The invention according to claim 4 is the invention according to claim 2 or 3.
In the strain inspection method according to, in the diagonal distortion amount,
Select a maximum diagonal distortion amount, including a lattice of the maximum diagonal strain amount, the diagonal strain amount to form a maximum strain portion combining continuous gratings of a predetermined threshold value or more, included in the maximum strain portion. At least one of the maximum diagonal strain amount, the maximum angular strain amount, and the number of lattices is calculated by calculating the number of lattices and selecting the maximum angular strain amount from the angular strain amounts of the lattices included in the maximum strain portion.
The gist is that it is determined whether or not one is larger than a preset threshold value corresponding to each.

According to a fifth aspect of the present invention, there is provided a distortion inspection device for inspecting the distortion of the inspection object based on a reflection image from the inspection object, the projection means projecting a lattice pattern onto the inspection object. Image input means for inputting a reflection image of a grid pattern projected by the projection means and reflected by an inspection target; and distortion amount calculation means for calculating the distortion amount of each of the grids forming the grid pattern of the input reflection image. The point is to have and.

According to a sixth aspect of the present invention, in the strain inspection apparatus according to the fifth aspect, the strain amount calculating means is a diagonal strain amount calculating means for calculating a diagonal strain amount based on a difference between diagonal lines of the lattice. The gist is that it is composed of an angular distortion amount calculating means for calculating an angular distortion amount based on an angular difference between each side of the grating and the axis of the grating pattern.

According to a seventh aspect of the present invention, in the strain inspection apparatus according to the sixth aspect, the diagonal strain amount computing means computes a diagonal line difference of each lattice, and calculates the difference from the diagonal line difference of the surrounding lattices. The diagonal strain amount of the lattice is calculated, and the angular strain amount calculating means calculates the angular difference between each side of each lattice and the axis of the lattice pattern, and the lattice difference of the surrounding lattice is calculated based on the deviation from the angular difference of surrounding lattices. The point is that the amount of angular distortion is calculated.

The invention described in claim 8 is the invention according to claim 6 or 7.
In the distortion inspection device according to, among the diagonal distortion amount,
Strain that includes a first selection unit that selects the maximum diagonal distortion amount and a grid having the maximum diagonal distortion amount, and that forms a maximum distortion portion by combining continuous gratings whose diagonal distortion amount is equal to or greater than a predetermined threshold value. Part forming means, grid number computing means for computing the number of lattices included in the maximum strain portion, and second selecting means for selecting the maximum angular strain amount of the angular strain amounts of the lattice included in the maximum strain portion. And at least one of the maximum amount of diagonal distortion, the maximum amount of angular distortion, and the number of grids by the first and second selection means and the number-of-grids calculation means is more than a preset threshold value corresponding to each. The gist is to have a determining means for determining whether or not it is large.

Therefore, according to the invention described in claim 1,
A grid pattern composed of a plurality of grids is projected onto the inspection object, the distortion amount of each grating of the reflection grating pattern reflected by the inspection object is calculated, and the acceptance / rejection of the inspection object is inspected based on the distortion amount.

According to the second aspect of the invention, as the strain amount of each lattice, a diagonal strain amount based on the diagonal difference of the lattice,
An angular distortion amount based on an angular difference between each side of the grid and the axis of the grid pattern is calculated.

According to the third aspect of the invention, the amount of diagonal distortion of the lattice is calculated from the difference between the calculated diagonal difference of the lattice and the diagonal difference of the surrounding lattices. Further, the amount of angular distortion of the lattice is calculated from the deviation between the calculated angular difference of the lattice and the angular difference of the surrounding lattices.

According to the fourth aspect of the present invention, the maximum diagonal distortion amount is selected from among the diagonal distortion amounts, and the maximum diagonal distortion amount is included in the lattice, and the diagonal distortion amount is continuously equal to or more than a predetermined threshold value. The maximum strained portion is formed by connecting the lattices. The number of lattices included in the maximum strain portion is calculated, and the maximum amount of angular strain is selected from the angular strain amounts of the lattice included in the maximum strain portion. Then, it is determined whether or not at least one of the maximum diagonal strain amount, the maximum angular strain amount, and the number of grids is larger than a preset threshold value corresponding to each, and the pass / fail of the inspection target is determined. It

According to the fifth aspect of the present invention, the projection means projects the lattice pattern onto the inspection object, and the reflection image of the lattice pattern reflected by the inspection object is input by the image input means. Then, the distortion amount of each lattice forming the lattice pattern of the reflected image input by the distortion amount computing means is computed.

According to the sixth aspect of the invention, the strain amount calculating means is composed of a diagonal strain amount calculating means and an angular strain amount calculating means. The diagonal distortion amount calculation means calculates the diagonal distortion amount based on the difference between the diagonal lines of the lattice, and the angular distortion amount calculation means calculates the angular strain amount based on the angular difference between each side of the lattice and the axis of the lattice pattern. Is calculated.

According to the seventh aspect of the present invention, the diagonal distortion amount calculation means calculates the diagonal line difference of each lattice, and the diagonal strain amount of the lattice is calculated by the deviation from the diagonal line difference of the surrounding lattices. . Further, the angular distortion amount calculation means calculates the angle difference between each side of each lattice and the axis of the lattice pattern,
The angular distortion amount of the lattice is calculated from the deviation from the angle difference of the surrounding lattice.

According to the invention described in claim 8, the first aspect is further provided.
The selection means, the strained portion formation means, the lattice number calculation means, the second selection means, and the determination means are provided. The maximum diagonal distortion amount is selected from the diagonal distortion amounts by the first selecting means. The strained portion forming unit joins continuous lattices including a lattice having the maximum diagonal strain amount and having a diagonal strain amount equal to or more than a predetermined threshold value to form the maximum strained portion. The number of grids included in the maximum strain section is calculated by the number-of-grids calculation means.
The second selection means selects the maximum angular distortion amount from the angular distortion amounts of the lattice included in the maximum distortion part. Then, at least one of the maximum diagonal distortion amount, the maximum angular distortion amount, and the number of grids by the first and second selection means and the number-of-grids calculation means is preset by the judgment means in correspondence with each other. It is determined whether it is larger than the value.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a schematic front view of the strain inspection apparatus 11, and FIG. 2 is a schematic side view of the strain inspection apparatus 11.

A three-point support base 12 is fixed on the floor surface 12 of the strain inspection device 11. On the three-point support 12,
A mirror M, which is an object to be inspected and is conveyed by a conveying device (not shown), is placed. The three-point support 12 is used to center the placed mirror M.

A camera 13 is provided above the three-point support base 12, and the camera 13 is supported by a slider 14 so as to be horizontally movable in the front-rear direction (front and back directions in the drawing in FIG. 1). A projection lens 16 supported by a support plate 15 is arranged between the three-point support 12 and the camera 13. Then, the mirror M supported by the three-point support 12, the projection lens 16, and the camera 13
Are arranged so that their optical centers coincide with each other.

The camera 13 has a line CCD having a predetermined number of pixels (5000 pixels in this embodiment). The camera 13 is moved in the horizontal direction by the slider 14, and in accordance with the movement, the images of each line are sequentially captured via the projection lens 16 to capture the reflected image of the entire mirror M.

The mirror M supported by the three-point support base 12
Is a mirror used for a door mirror of an automobile, for example, and as shown in FIG. 4, has a substantially oval shape in which the horizontal direction (the horizontal direction in FIG. 4) is longer than the vertical direction (the vertical direction in FIG. 4). Has been formed. The camera 13 is arranged so as to capture a reflected image of the mirror M in the lateral direction (left and right direction in FIG. 1) as image data for one line. Then, the camera 13 is moved by the slider 14 in the vertical direction of the mirror M (the front-back direction in FIG. 1 and the left-right direction in FIG. 2) and captures the reflected image of the entire mirror M via the projection lens 16.

A light projecting panel 17 is provided on the side of the mirror M and behind the distortion inspection device 11 (on the left side in FIG. 2). The light projecting panel 17 is a box, and a lattice pattern 18 is formed on the front side surface 17a. The lattice pattern 18 is a mesh formed by orthogonal parallel line groups arranged at regular intervals (horizontal direction in FIG. 1) and vertical direction (vertical direction in FIG. 1). In the form, it is formed by a plurality of light emitting points 19 arranged at the intersections of the parallel line groups. Those light emitting points 1
9 is formed by, for example, a plurality of through holes formed in the side surface 17a along the horizontal direction and the vertical direction, and a lamp (all not shown) provided in the light projecting panel 17. Therefore, the light projecting panel 17 projects the grid pattern 18 by the plurality of light emitting points 19.

A half mirror 20 is provided above the three-point support 12 and between the projection lens 16. The half mirror 20 is attached so as to be inclined at a predetermined angle, is used to reflect an image (grating pattern 18) projected from the light projecting panel 17 and project the image onto the mirror M to be inspected. The lattice pattern 18 can be projected on the entire surface of the mirror M by the half mirror 20. Therefore, unlike the conventional distortion rate test (JIS D 5705) for automobile mirrors, the center of the mirror M can be reliably inspected.

Then, the mirror M passes through the projected grating pattern 18 through the half mirror 20 and the distortion inspection device 1
Reflect above 1. The reflected grid pattern 1
8 is guided to the camera 13 via the projection lens 16,
It is captured as image data by the camera 13. The image data captured by the camera 13 is processed by the image processing device 21, which will be described later, to detect the distortion of the reflected image of the mirror M.

Next, the electrical configuration of the strain inspection device 11 is shown in FIG.
It will be described according to. The camera 13 is connected to the image processing device 21. The camera 13 transmits the captured image data of the mirror M to the image processing device 21.

The image processing device 21 includes a camera driver 2
2 are connected. The camera driver 22 is the camera 1
3 is used to supply a driving power source, a clock signal, and the like. The camera 13 takes in the image data for one line by the driving power and the clock signal supplied from the camera driver 22, and outputs the taken-in image data to the image processing device 21.

A motor driver 23 is connected to the image processing device 21. The motor driver 23 is used to operate the slider 14. Slider 1
Reference numeral 4 denotes an air slider with a linear motor in the present embodiment, which drives a linear motor (not shown) based on a signal supplied from the motor driver 23 to horizontally move the camera 13.

Therefore, the image processing device 21 drives and controls the slider 14 via the motor driver 23 to control the camera 1.
3 is moved horizontally, and the camera 13 is driven and controlled via the camera driver 22 to input the image data of the entire mirror M from the camera 13.

As described above, the slider 14 is an air slider with a linear motor, and is floated by air supplied from an air supply source (not shown) via the air clean unit 24 to move the camera. Thirteen
It is designed to prevent vibration when moving horizontally.

The image processing device 21 includes a reflection image memory 21.
a, a data memory 21b, and a program memory (not shown). The reflection image memory 21a is used by the camera 13
It is used to store the image data of the reflected image of the mirror M input from. The data memory 21b is used for the calculation result in the processing of the image processing device 21 and the reflection image memory 21a.
It is used to store correction data and the like for correcting the image data stored in.

A processing program for image processing is stored in the program memory. Image processing device 21
Inputs a reflection image of the entire mirror M as image data based on a processing program, and performs a distortion detecting operation for detecting distortion of the mirror M based on the image data. In the distortion detecting operation, the image processing device 21 stores the image data taken from the camera 13 in the reflection image memory 21a. Then, the image processing device 21 uses the reflection image memory 21a.
The distortion of the mirror M is detected based on the image data stored in the table, and the pass / fail judgment of the mirror M is performed based on the distortion.

The half mirror 20 and the projection lens 16
May include distortion with respect to the transmitted or reflected image, and the image data stored in the reflected image memory 21a includes distortion in the half mirror 20 and the projection lens 16. These distortions appear at the same place unless the half mirror 20 and the projection lens 16 are moved or replaced. Therefore, the correction data is created in advance from the image data input using the optical reference and the correction data is stored in the data memory 21b. Then, the image processing apparatus inputs the reflection image data of the mirror M to be inspected, and adds the correction data to the reflection image data, whereby the half mirror 2
0, distortion of the projection lens 16 is corrected.

A display 25 is connected to the image processing device 21. The image processing apparatus 21 is configured to display the inspection result of the mirror M, the operation state of the apparatus 21, and the like on the display 25. With this configuration, the operator can easily confirm the inspection result of the mirror M.

Next, the operation of the strain inspection device 11 configured as described above will be described. The image processing device 21 drives and controls the camera driver 22 and the motor driver 23 based on the processing program, horizontally moves the camera 13, captures the reflected image of the entire mirror M, and stores it in the reflected image memory 21a. The reflection image of the mirror M is shown in FIG. FIG.
In FIG. 3, in order to make it easier to understand the distortion of the mirror M, each light emitting point 19 forming the lattice pattern 18 is shown as a line segment connecting in the vertical direction and the horizontal direction, and the light emitting point 19 is omitted. The vertical and horizontal pitches of the lattice pattern 18 are shown larger than actual.

As shown in FIG. 4, there is distortion on the left side (left side in the figure) of the mirror M, and the distortion distorts the reflection image of the grating pattern 18. The image processing device 21
Of the light emitting points 19 forming the lattice pattern 18, four light emitting points 19 form a quadrangular region (hereinafter, this region is referred to as a lattice) 31. When this grating is compared on the left and right sides of the mirror M, the distortion-free right grating 31 (for example, the grating 31a) is substantially square. On the other hand, in the distorted left-side grating 31 (for example, the grating 31b), each side connecting the four light-emitting points 19 has an angle corresponding to the distortion and is distorted. Therefore, the distortion of the mirror M can be detected by measuring the distortion of the grating 31.

That is, the image processing device 21 determines the coordinates of each light emitting point 19 of the grid pattern 18 based on the image data stored in the reflection image memory 21a. Each light emitting point 1
As the coordinates of 9, the horizontal direction (the horizontal direction in FIG. 4) is Y
The axis and the vertical direction (vertical direction in FIG. 4) are the X axis, and the position on each axis is the coordinate value of each light emitting point 19.

Next, the image processing device 21 calculates the distortion amount of each lattice 31 (distortion amount calculation means). As shown in FIG.
In the case of the lattice 31c constituted by the light emitting points 19a to 19d, the strain amount of the lattice 31c constitutes the difference between the two diagonal lines 32a and 32b of the lattice 31c and each lattice 31 with respect to the reference X-axis and Y-axis. It is composed of four sides 33a to 33d and the angle difference between them.

As shown in FIG. 5, the grating 31c at the place where the mirror M is distorted is different in the length of the two diagonal lines 32a and 32b due to the distortion of the grating 31c. Further, in the distorted lattice 31c, each side 33a to 33d has X
Angles θ1 to θ4 are set according to the strain with respect to the axis (horizontal direction) and the Y axis (vertical direction). Therefore, the image processing device 21 calculates the difference between the lengths of the two diagonal lines 32a and 32b (diagonal line difference) and the average of the angles θ1 to θ4 (angle difference).

The diagonal difference D of the grid 31c is the coordinates of the four light emitting points 19a to 19d (X1, Y1), (X2, Y2), (X3,
Y3), (X4, Y4)

[0046]

[Equation 1]

And the angular difference A of the grating 31c is

[0048]

[Equation 2]

It is represented by In addition, the image processing device 21
With respect to the diagonal line difference D and the angle difference A of each lattice 31 obtained by the above equation, the deviation from the surrounding lattice 31 is obtained. These deviations are small when the distortion of the mirror M is small (the change in the curvature of the reflecting surface is small), and become large when the distortion is large (the change in the curvature of the reflecting surface is large). It becomes the amount. When the distortion is small, the distortion of the reflected image is not noticeable, and when the distortion is large, the distortion of the reflected image is noticeable. Therefore, the calculated distortion amount is compared with a predetermined threshold value, and when the calculated distortion amount is larger than the threshold value, the mirror M is determined to be defective.

Therefore, as shown in FIG.
The diagonal distortion amount DH of the diagonal difference D of 1c is D1-D8, where the diagonal differences of the lattices around the lattice 31c to be obtained are

[0051]

(Equation 3)

Is represented by Further, as shown in FIG. 6B, the angular strain amount AH of the angular difference A with respect to the axis of each side 33a to 33d of the grating 31c is the angular difference A1 to A8 of the gratings around the grating 31c to be obtained. Then,

[0053]

(Equation 4)

Is as follows. Then, the image processing device 21 obtains the diagonal distortion amount DH and the angular distortion amount AH for each lattice 31 of the input reflected image of the mirror M, and stores them in the data memory 21b corresponding to each lattice 31. . The diagonal strain amount DH corresponding to each lattice 31 is shown in FIG. 7, and the angular strain amount AH corresponding to each lattice 31 is shown in FIG.

In FIGS. 7 and 8, the value at “0” on both the vertical and horizontal axes is the center of the reflected image of the mirror M, and the side where the distortion is large in FIGS. 7 and 8 ( Figure 7
And the right side portion in FIG. 8 is shown. In addition, the strain amounts shown in the figure are shown as [× 10 ⁴ ].

Next, the image processing device 21 performs a correction process. This correction processing is spherical surface correction processing, and each grid 31
The diagonal distortion amount DH and the angular distortion amount AH are calculated based on the correction data stored in the data memory 31b. For this correction data, the diagonal distortion amount DH and the angular distortion amount AH are similarly calculated by using a true spherical surface in advance. Then, these distortion amounts DH and AH are stored in the data memory 21b as correction data. The image processing apparatus 21 subtracts this correction data from the diagonal distortion amount DH and the angular distortion amount AH of the mirror M, thereby performing spherical correction on the mirror M.

Then, the image processing device 21 compares the diagonal distortion amount DH obtained for each lattice 31 as described above with a predetermined threshold value. This threshold value is obtained in advance by experiments and stored in the data memory 21b.

When the diagonal distortion amount DH is smaller than the threshold value, it means that the strain in the lattice 31 is smaller than that of the surrounding lattice 31, and when the diagonal strain amount DH is larger than the threshold value, the lattice is Distortion at 31 is the surrounding lattice 31
Means great against. Then, the image processing apparatus 21 joins the lattices 31 having the diagonal distortion amount DH larger than the threshold value to determine a plurality of (all existing) shapes of the strained portions 41 (determined strained portions). In this embodiment, the diagonal distortion amount DH is "0.012" (in the drawing, "1"
20 ") The above-mentioned lattices 31 are joined to determine the shape of the strained portion.

Next, the image processing device 21 determines the diagonal distortion amount D.
The maximum diagonal strain amount DHM of the strained portion 41 determined by H
Select Further, the image processing device 21 determines the distortion section 41 including the selected maximum diagonal distortion amount DHM as the maximum distortion section 41a (selects the maximum distortion section), and calculates the number of the lattices 31 included in the maximum distortion section 41a. (Calculate the number of grids). Then, the image processing device stores the calculated maximum diagonal distortion amount DHM and the number of grids in the data memory 21b. In FIG. 7, the maximum diagonal strain amount DHM is “0.0392” (“392” in the drawing), and the lattice number of the maximum strain portion 41a including the maximum diagonal strain amount DHM is “55”.

Then, as shown in FIG. 8, the image processing device 21 selects the maximum angular distortion amount AHM from the angular distortion amounts AH of the respective gratings 31 in the maximum distortion portion 41a, and selects the selected maximum angular distortion amount. The quantity AHM is stored in the data memory 21b.
In FIG. 8, the maximum angular strain amount AHM is “0.016”.
("160" on the drawing).

Next, the image processing device 21 performs a determination process. In this determination process, the image processing device 21 calculates the maximum diagonal distortion amount D previously calculated and stored in the data memory 21b.
The pass / fail judgment of the mirror M to be inspected is performed based on HM, the number of gratings, or the maximum amount AHM of angular distortion. That is, the image processing device 21 compares the maximum diagonal distortion amount DHM with a predetermined diagonal distortion amount threshold value. In addition, the image processing device 21
The number of grids is compared with a predetermined threshold number of grids. Furthermore, the image processing device 21 compares the maximum angular distortion amount AHM with a predetermined angular distortion amount threshold value. These threshold values are previously obtained by experiments and stored in the data memory 21b.

If at least one of the maximum diagonal distortion amount DHM, the number of lattices, and the maximum angular distortion amount AHM is larger than each threshold value, the image processing apparatus 21 causes the image processing apparatus 21 to detect the mirror M to be inspected. It is determined that the distortion is large and defective, and the determination result is output to the display 25. Based on the determination result output to the display 25, the operator can easily determine whether the mirror M is acceptable or not.

In the present embodiment, the image processing device 21 has a maximum diagonal distortion amount DHM of "0.04"("400" in the drawing) or more and a maximum angular distortion amount AHM of "0.01".
The mirror M is judged to be unacceptable when 8 "(180 in the drawing) or more and at least one of which the number of lattices is 19 or more is applicable. Therefore, in the data shown in FIGS. 7 and 8, the number of grids is “55”.
Therefore, the image processing device 21 determines that the mirror M, which is the inspection target that has acquired this data, has failed.

As described above, according to the present embodiment,
The following effects are obtained. (1) Lattice pattern 1 for the mirror M to be inspected
8 is projected and the distortion of each grating 31 is calculated based on the image data of the grating pattern 18 reflected by the mirror M to detect the distortion of the mirror M. As a result, it is possible to make the detection accuracy in the central portion and the peripheral portion of the mirror M the same and detect the peripheral portion more finely than in the conventional case.

(2) The image processing device 21 corrects the distortion of each grating 31 forming the grating pattern 18 of the reflected image of the mirror M.
The diagonal difference D between the diagonal lines 32a and 32b of the lattice 31, and
Angular difference A between the sides 33a to 33d forming the grid 31 and the axis
And ask. Then, the image processing device 21 uses the grid 3
The diagonal difference D and the angular difference A of 1 were determined as the diagonal strain amount DH and the angular strain amount AH of the lattice 31 by obtaining the deviations according to the diagonal difference and the angular difference of the lattices around the lattice 31. As a result, both distortion amounts DH and AH on the curved reflecting surface that change with a substantially constant curvature have small values. Therefore, not only the flat reflecting surface but also the curved reflecting surface can be detected for distortion.

(3) The image processing device 21 uses the grid 3 in which the diagonal distortion amount DH of each grid 31 is equal to or more than a predetermined threshold value.
1 is joined to form a strained portion 41, and the strained portion 41 having the largest number of lattices 31 forming the strained portion 41 is set to the maximum strained portion 41a.
And The image processing device 21 sets the largest value of the diagonal distortion amount DH and the angular distortion amount AH of the lattice 31 included in the maximum distortion portion 41a as the maximum diagonal distortion amount DHM and the maximum angular distortion amount AHM. Then, the image processing device 21 determines that the maximum diagonal distortion amount DH
M, the number of lattices of the maximum strain section 41a, and the maximum angular strain amount AHM
If at least one of them is larger than the threshold value set in advance, the mirror M to be inspected is determined to be defective. As a result, the distortion of the mirror M can be easily detected, and the pass / fail of the mirror M can be determined.

The present invention may be modified as follows, and in that case, the same operation and effect can be obtained. (1) In the above-described embodiment, the reflection image of the mirror M is captured by the single camera 13, but FIGS.
As shown in 0, a plurality of (four in FIG. 10) cameras 13a to 13d may capture the reflection image of the mirror M. At that time, a screen 51 is provided between the projection lens 16 and the cameras 13a to 13d, the reflected image of the mirror M is projected on the screen 51, and the reflected image of the projected lattice pattern 18 is reflected by the cameras 13a to 13d.
To be captured by According to this configuration, an image with higher resolution can be obtained, so that the distortion of the mirror M can be detected more accurately.

(2) In the above embodiment, the lattice pattern 18 is formed by the plurality of light emitting points 19 arranged in the horizontal and vertical directions, but the camera 13 surely detects the intersection of the lattice patterns 18. Any method may be used as long as it is possible. For example, the side surface 17a
Is formed of a transparent plate such as acrylic, and the portions other than the light emitting points 19 are masked by painting or the like. The end faces of the optical fibers are arranged corresponding to the respective light emitting points 19, and lasers, LEDs, halogen lamps, and xenon are attached to the optical fibers. A method of guiding light from a lamp or the like, or directly disposing a laser, an LED or the like at each light emitting point 19 may be used.

(3) In the above embodiment, the light emitting point 19 is formed by projecting light with a circular cross section, but any shape may be formed as long as it is possible to reliably detect the intersection of the lattice patterns 18. You may implement. For example, it may be formed in a cross shape, a polygonal shape, a ring shape, or the like.

(4) In the above-mentioned embodiment, the grid pattern 18 is projected by the light emitting points 19 provided at the respective intersections, but the entire horizontal and vertical lines corresponding to the grid pattern 18 are made to emit light. You may make it project.

(5) In the above embodiment, the grid pattern 18 is formed by the light emitting points 19 arranged in the horizontal and vertical directions. However, the light emitting points 19 are arranged along two axes that have an arbitrary angle and are orthogonal to each other. Arrange the grid pattern 18
May be formed.

(6) In the above-described embodiment, the grid pattern 18 is a mesh formed by orthogonal parallel line groups arranged in the horizontal and vertical directions, but intersects at an arbitrary angle. It may be implemented as a mesh formed by a plurality of parallel line groups at equal intervals. For example, a mesh of regular triangles formed by three parallel line groups that intersect at 60 ° may be used as a grid pattern, and light emitting points 19 may be provided at the intersections to project the grid pattern. In the case of this configuration, instead of the diagonal difference D, the average of the differences between the sides of the triangle of the reflection image is used to determine the distortion amount of the lattice.

(7) In the above embodiment, the strain amount of the focused grid 31c is calculated based on the focused grid 31c and eight surrounding grids. The number may be changed as appropriate. For example,
The distortion amount of the lattice 31c may be calculated based on four lattices at the top, bottom, left and right of the lattice 31c of interest, or 24 lattices around the lattice.

(8) In the above embodiment, the image processing device 21 calculates the maximum diagonal distortion amount DHM and the maximum distortion portion 4
The number of grids of 1a and the maximum angular distortion amount AHM may be displayed on the display 25.

(9) In the above embodiment, the image processing device 21 outputs the determination result of the mirror M to the external device,
The external device may be configured to exclude the defective mirror M from the transport device.

(10) In the above embodiment, the slider 1
Although the air flying type air slider with a linear motor is used in FIG. 4, a bearing type slider may be used. (11) In the above embodiment, the image processing device 21
Alternatively, after obtaining the maximum diagonal strain amount DHM, continuous lattices including the maximum diagonal strain amount DHM may be combined to form the maximum strain portion 41a.

Although the respective embodiments of the present invention have been described above, technical ideas other than the claims which can be understood from the respective embodiments will be described below together with their effects. (A) In the distortion inspection device according to any one of claims 5 to 8, the projection means is a projection panel which is arranged laterally of an inspection target and has a lattice pattern formed on its side surface, and the projection panel. A distortion inspection device including a half mirror that projects a lattice pattern onto an inspection target. According to this configuration, it is possible to project the lattice pattern on the entire surface of the inspection target.

(B) In the distortion inspection apparatus according to any one of claims 5 to 8, the image input means is line C.
A distortion inspection device comprising a camera made of a CD and a slider for moving the camera horizontally. With this configuration, it is possible to increase the number of pixels to be input, and it is possible to accurately input the image data of the entire surface of the inspection target.

In this specification, means and members relating to the constitution of the invention are defined as follows. The lattice pattern means an imaginary mesh formed by parallel line groups that intersect at equal intervals, and is not limited to a mesh formed by orthogonal parallel line groups, but may be formed by parallel line groups that intersect at any angle. It also includes the formed mesh.

[0080]

As described above in detail, according to the present invention, there is provided a strain inspection method and a strain inspection apparatus capable of inspecting a plane mirror and a curved mirror and performing a fine inspection in a peripheral portion. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a strain inspection apparatus according to an embodiment.

FIG. 2 is a schematic side view of the strain inspection device according to the embodiment.

FIG. 3 is a block circuit diagram showing an electrical configuration of the distortion inspection device.

FIG. 4 is a plan view of a mirror showing a distorted state.

FIG. 5 is a principle diagram for explaining strain measurement.

FIG. 6A is an explanatory view showing a diagonal line difference of the lattice, and FIG. 6B is an explanatory view showing an angle difference of the lattice.

FIG. 7 is an explanatory diagram showing the amount of diagonal distortion of each lattice.

FIG. 8 is an explanatory diagram showing the amount of angular difference strain of each grating.

FIG. 9 is a schematic front view of another strain inspection device.

FIG. 10 is a schematic side view of another strain inspection device.

[Explanation of symbols]

Reference numeral 17 ... Projection panel as projection means, 20 ... Half mirror as projection means, 18 ... Lattice pattern, 13 ... Camera as image input means, 31 ... Distortion amount calculation means, diagonal distortion amount calculation means, angular distortion amount calculation Means, first selecting means, strained portion forming means, lattice number calculating means, second selecting means, and
An image processing device as a determination means, M ... A mirror as an inspection target.

Claims (8)

[Claims] 1. A distortion inspection method for detecting distortion of an inspection object based on a reflection image from the inspection object, comprising projecting a lattice pattern composed of a plurality of lattices onto the inspection object, A strain inspecting method, wherein a strain amount of each lattice of the reflected reflection lattice pattern is calculated, and whether the inspection target is passed or not is inspected based on the strain amount. 2. The strain inspection method according to claim 1, wherein the strain amount of each of the lattices is a diagonal strain amount based on a diagonal difference of the lattice and an angular difference between each side of the lattice and an axis of the lattice pattern. A distortion inspection method for calculating an angular distortion amount based on the above. 3. The strain inspection method according to claim 2, wherein the amount of diagonal distortion of the lattice is calculated from the difference between the calculated diagonal difference of the lattice and the diagonal difference of surrounding lattices, and the calculated angular difference of the lattice. And a strain inspection method in which the angular strain amount of the lattice is calculated by the deviation from the angular difference of the surrounding lattice. 4. The strain inspection method according to claim 2, wherein the maximum diagonal strain amount is selected from the diagonal strain amounts, and the maximum diagonal strain amount is included, and the diagonal strain amount is predetermined. A maximum strain portion formed by combining continuous lattices equal to or more than a threshold value is formed, and the number of lattices included in the maximum strain portion is calculated. And a strain inspection for determining whether or not at least one of the maximum diagonal strain amount, the maximum angular strain amount, and the number of grids is greater than a preset threshold value corresponding to each. Method. 5. A distortion inspection apparatus for inspecting distortion of an inspection object based on a reflection image from the inspection object, comprising: projection means for projecting a lattice pattern onto the inspection object; A strain inspection apparatus including an image input unit for inputting a reflection image of a lattice pattern reflected by an inspection target, and a strain amount calculation unit for calculating a strain amount of each lattice forming the lattice pattern of the input reflection image. . 6. The strain inspecting apparatus according to claim 5, wherein the strain amount calculating unit calculates a diagonal strain amount based on a difference between diagonal lines of the lattice, and each side of the lattice, A strain inspecting device comprising: an angular strain amount calculating means for calculating an angular strain amount based on an angular difference from an axis of a lattice pattern. 7. The strain inspection apparatus according to claim 6, wherein the diagonal distortion amount calculation means calculates a diagonal difference of each lattice and calculates a diagonal strain amount of the lattice by a deviation from a diagonal difference of surrounding lattices. The angular distortion amount calculating means calculates an angular difference between each side of each lattice and the axis of the lattice pattern, and calculates an angular strain amount of the lattice by a deviation from an angular difference between surrounding lattices. Distortion inspection device. 8. The strain inspection apparatus according to claim 6, wherein the maximum diagonal distortion amount is selected from the diagonal distortion amounts.
Selecting means, a strain portion forming means for forming a maximum strain portion by connecting a continuous lattice having a diagonal strain amount equal to or greater than a predetermined threshold, including a lattice having the maximum diagonal strain amount, and the maximum strain portion. And a second selection unit for selecting the maximum angular distortion amount of the angular distortion amounts of the grating included in the maximum distortion unit, and the first and second Judgment means for judging whether or not at least one of the maximum diagonal distortion amount, the maximum angular distortion amount, and the number of grids by the selection means and the number-of-grids calculation means is larger than a preset threshold value corresponding to each. And a strain inspection device.