JP3340296B2 - Distortion inspection method and distortion inspection device - Google Patents

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 an inspection apparatus, and more particularly, to an inspection method and an inspection apparatus for detecting a distortion of a reflection surface such as a mirror.

[0002]

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

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

On the other hand, in the distortion factor test, an image of a concentric scale at a predetermined interval and an image of an octant line passing through the center of the scale are projected on a mirror surface, and an image of the concentric scale of the mirror surface is captured by a camera or the like. Then, the distortion factor is calculated based on the average radius of the concentric reflection image and the radius of the maximum or minimum reflection image. According to this method, since the concentric scale is used, the plane mirror and the curved mirror can be inspected.

[0005]

However, in the above-mentioned distortion factor test, the average radius of the reflection image of the concentric circle and the radius of the maximum or minimum reflection image are measured by measuring the interval between the intersections of the concentric circle and the octants. By seeking. Therefore, since only the displacement in the radiation direction is detected, the detection accuracy may be different for the direction of the distortion. In addition, in the peripheral part, the interval (circumferential interval) between the eight equal lines is wider in the peripheral part than in the central part, so that the inspection density becomes coarse, and the strain between the eight equal lines cannot be detected. There is.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to inspect a plane mirror and a curved mirror and to perform a fine inspection in a peripheral portion. An object of the present invention is to provide a method and a distortion inspection device.

[0007]

According to a first aspect of the present invention, there is provided a distortion inspection method for detecting distortion of an inspection target based on a reflection image from the inspection target. The inspection target projects a lattice pattern composed of a plurality of lattices, and the diagonal difference between each lattice of the reflection lattice pattern reflected by the inspection target and the diagonal difference between surrounding lattices.
Is the diagonal distortion amount, and each grid with respect to the reference axis
The difference between the angle difference between the sides constituting
The gist is that the amount of angular distortion is calculated, the amount of diagonal distortion and the amount of angular distortion of each lattice are calculated, and the pass / fail of the test object is inspected based on the amount of diagonal distortion and the amount of angular distortion of each lattice .

[0008]

[0009]

According to a second aspect of the present invention, in the distortion inspection method according to the first aspect , a maximum diagonal distortion amount is selected from the diagonal distortion amounts, and a lattice of the maximum diagonal distortion amount is included.
Diagonal distortion is formed to form a maximum distortion portion combining continuous lattices equal to or greater than a predetermined threshold, and the number of lattices included in the maximum distortion portion is calculated. Among them, the maximum amount of angular distortion is selected, the maximum amount of diagonal distortion,
The gist is that it is determined whether or not at least one of the maximum amount of angular distortion and the number of lattices is larger than a preset threshold value corresponding to each.

According to a third aspect of the present invention, there is provided a distortion inspection apparatus for inspecting a distortion of the inspection object based on a reflection image from the inspection object, wherein the projection unit projects a lattice pattern on the inspection object. Image input means for inputting a reflection image of a grid pattern projected by the projection means and reflected by the inspection object; and a diagonal difference between each grid and a surrounding grid constituting the grid pattern of the input reflected image. Bias with
The difference is defined as the amount of diagonal distortion, and each grid is constructed with respect to the reference axis.
The difference between the angle difference between the formed sides and the angle difference
The gist of the present invention is to provide a distortion amount calculating means for calculating a diagonal distortion amount and an angular distortion amount of each lattice as a distortion amount.

[0012]

[0013]

[0014] According to a fourth aspect of the invention, the distortion inspecting apparatus according to claim 3, of the diagonal distortion amount, a first selection means for selecting the maximum diagonal distortion amount, the maximum diagonal distortion amount A strain portion forming means for forming a maximum strain portion by combining continuous grids including a grid and having a diagonal distortion amount equal to or greater than a predetermined threshold, and a grid number calculation for calculating the number of grids included in the maximum strain portion Means, and second selecting means for selecting the maximum amount of angular distortion from among the amount of angular distortion of the lattice included in the maximum distortion section,
Whether at least one of the maximum diagonal distortion amount, the maximum angular distortion amount, and the number of lattices by the first and second selecting means and the lattice number computing means is larger than a preset threshold value corresponding to each of them. The gist of the present invention is to provide a determination means for determining whether or not the determination is made.

Therefore, according to the first aspect of the present invention,
A grid pattern composed of a plurality of grids is projected on the inspection target, and the deviation between the diagonal difference of each grid of the reflection grid pattern reflected by the inspection target and the diagonal difference of the surrounding grid is compared .
Configure each grid for the reference axis as the amount of angular distortion
The deviation between the side angle difference and the surrounding grid angle difference is defined as the amount of angular distortion.
Then, the amount of diagonal distortion and the amount of angular distortion of each grid are calculated, and each grid is calculated.
The pass / fail of the inspection target is inspected based on the diagonal distortion amount and the angular distortion amount.

[0016]

[0017]

According to the second aspect of the present invention, the maximum diagonal distortion amount is selected from the diagonal distortion amounts, the grid includes the maximum diagonal distortion amount, and the continuous diagonal distortion amount is equal to or more than a predetermined threshold value. A maximum strained portion is formed in which the lattices are combined. The number of grids included in the maximum distortion portion is calculated, and the maximum angular distortion amount is selected from the angular distortion amounts of the lattices included in the maximum distortion portion. Then, it is determined whether at least one of the maximum diagonal distortion amount, the maximum angle distortion amount, and the number of grids is larger than a threshold value set in advance corresponding to each of them, and whether the inspection target is acceptable or not is determined. You.

According to the third aspect of the present invention, the grid pattern is projected on the inspection object by the projection means, and the reflection image of the grid pattern reflected by the inspection object is input by the image input means. Then, the deviation between the diagonal difference of each of the lattices constituting the lattice pattern of the reflected image input by the distortion amount calculating means and the diagonal difference of the surrounding lattice is calculated as the diagonal distortion.
And the angles of the sides that make up each grid with respect to the reference axis
The deviation between the power difference and the angle difference of the surrounding grid is defined as the amount of angular distortion.
The amount of diagonal distortion and the amount of angular distortion of the lattice are calculated.

[0020]

[0021]

According to the fourth aspect of the present invention, the first
, A distorted portion forming means, a grid number calculating means, a second selecting means, and a judging means. The first diagonal distortion amount is selected by the first selecting means. Distortion portion forming means forms a maximum distortion portion by combining continuous lattices including a lattice having a maximum diagonal distortion amount and having a diagonal distortion amount equal to or greater than a predetermined threshold value. The number of grids included in the maximum distortion section is calculated by the number of grids calculating means.
The second selecting means selects the maximum angular distortion amount from the angular distortion amounts of the lattice included in the maximum distortion portion. Then, the determining means sets at least one of the maximum diagonal distortion amount, the maximum angular distortion amount, and the number of grids by the first and second selecting means and the number-of-grid calculating means, and sets the threshold corresponding to each of them in advance. It is determined whether it is greater 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 distortion inspection device 11, and FIG. 2 is a schematic side view of the distortion inspection device 11.

A three-point support base 12 is fixed on a floor surface 12 of the distortion inspection apparatus 11. On the three-point support 12,
A mirror M as an inspection object transported by a transport device (not shown) is mounted. 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 (the front and back direction in FIG. 1). A projection lens 16 supported by a support plate 15 is provided between the three-point support table 12 and the camera 13. The mirror M supported by the three-point support 12, the projection lens 16, and the camera 13
Are arranged such that their optical centers coincide with each other.

The camera 13 has a line CCD having a predetermined number of pixels (5000 pixels in the present embodiment). The camera 13 is moved in the horizontal direction by the slider 14, and sequentially captures an image for each line via the projection lens 16 in accordance with the movement, thereby capturing a reflection image of the entire mirror M.

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

A light projection panel 17 is provided on the side of the mirror M and behind the distortion inspection device 11 (left side in FIG. 2). The light projecting panel 17 is a box, and a lattice pattern 18 is formed on a front side surface 17a. The lattice pattern 18 is a mesh formed by orthogonally spaced parallel lines arranged in a horizontal direction (horizontal direction in FIG. 1) and a vertical direction (vertical direction in FIG. 1). In the embodiment, the light emitting device is formed by a plurality of light emitting points 19 disposed at the intersections of the parallel line groups. These luminous 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 (both 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 between the three-point support 12 and the projection lens 16. The half mirror 20 is attached to be inclined at a predetermined angle, and is used to reflect an image (lattice pattern 18) projected from the light projection 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 distortion factor test (JIS D 5705) of the conventional automobile mirror, the center of the mirror M can be inspected without fail.

Then, the mirror M passes the projected grating pattern 18 through the half mirror 20 and the strain inspection apparatus 1.
1. Reflect upward. The reflected grating pattern 1
8 is guided to the camera 13 via the projection lens 16,
The image is captured by the camera 13 as image data. The image data captured by the camera 13 is processed by an image processing device 21 described later, thereby detecting the distortion of the reflected image of the mirror M.

Next, the electrical configuration of the strain inspection apparatus 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 drive power supply, a clock signal, and the like. The camera 13 captures one line of image data by a driving power supply and a clock signal supplied from a camera driver 22, and outputs the captured 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 a motor driver 23 to move the camera 13 horizontally.

Accordingly, the image processing device 21 controls the driving of the slider 14 via the motor driver 23 to
3 is moved horizontally, and the camera 13 is driven and controlled via a camera driver 22 to input 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 floats and moves by air supplied from an air supply source (not shown) via an air clean unit 24, thereby moving the camera. 13
Is prevented from vibrating 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 21 a
Is used to store the image data of the reflection image of the mirror M input from the camera. The data memory 21b stores calculation results in the processing of the image processing device 21 and the reflection image memory 21a.
Is used to store correction data for correcting the image data stored in the.

A processing program for image processing is stored in the program memory. Image processing device 21
Performs a distortion detection operation of inputting a reflection image of the entire mirror M as image data based on a processing program and detecting distortion of the mirror M based on the image data. In the distortion detection operation, the image processing device 21 stores the image data captured from the camera 13 in the reflection image memory 21a. Then, the image processing device 21 includes a reflection image memory 21a.
The distortion of the mirror M is detected based on the image data stored in the mirror M, 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 for a 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 location unless the half mirror 20 and the projection lens 16 are moved or replaced. Therefore, correction data is created in advance from the input image data using an optical reference or the like, 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 correction data to the reflection image data, thereby forming the half mirror 2.
0, the distortion of the projection lens 16 is corrected.

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

Next, the operation of the distortion inspection apparatus 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, moves the camera 13 horizontally, captures the reflection image of the entire mirror M, and stores it in the reflection image memory 21a. FIG. 4 shows a reflection image of the mirror M. FIG.
In FIG. 5, in order to make the distortion of the mirror M easy to understand, each light emitting point 19 constituting the lattice pattern 18 is shown as a line connecting in the vertical and horizontal directions, 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 causes the reflection image of the grating pattern 18 to be distorted. The image processing device 21
The four light-emitting points 19 among the light-emitting points 19 forming the lattice pattern 18 form a rectangular region 31 (hereinafter, this region is referred to as a lattice). When this grating is compared on the left and right sides of the mirror M, the right grating 31 without distortion (for example, grating 31a) is substantially square. On the other hand, in the distorted left lattice 31 (for example, the lattice 31b), each side connecting the four light emitting points 19 has an angle corresponding to the distortion and is distorted. Therefore, by measuring the distortion of the grating 31, the distortion of the mirror M can be detected.

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. In addition, each light emitting point 1
As the coordinates of No. 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 amount of distortion of each lattice 31 (distortion amount calculating means). As shown in FIG.
In the case of the grating 31c constituted by the light emitting points 19a to 19d, the amount of distortion of the grating 31c constitutes the difference between the two diagonal lines 32a and 32b of the grating 31c and each of the gratings 31 with respect to the reference X-axis and Y-axis. And the angle difference between the four sides 33a to 33d.

As shown in FIG. 5, the grating 31c in the place where the mirror M is distorted has different lengths of two diagonal lines 32a and 32b as a distortion of the grating 31c. Also, in the distorted lattice 31c, each side 33a to 33d has X
The angles θ1 to θ4 correspond to the distortion 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 these two diagonal lines 32a and 32b (diagonal difference) and the average of the angles θ1 to θ4 (angle difference).

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

[0046]

(Equation 1)

The angular difference A of the grating 31c is

[0048]

(Equation 2)

Is represented by Further, the image processing device 21
With respect to the diagonal difference D and the angle difference A of each grid 31 obtained by the above formula, the deviation from the surrounding grid 31 is obtained. These deviations are small when the distortion of the mirror M is small (the change in the curvature of the reflection surface is small), and large when the distortion is large (the change in the curvature of the reflection surface is large). Amount. When the distortion is small, the distortion of the reflected image is hardly conspicuous, and when the distortion is large, the distortion of the reflected image is conspicuous. Therefore, the calculated distortion amount is compared with a predetermined threshold value, and if 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 represented by D1 to D8, where the diagonal differences of the lattices around the lattice 31c to be obtained are D1 to D8.

[0051]

(Equation 3)

Is represented by As shown in FIG. 6B, the angular distortion AH of the angle difference A with respect to the axis of each side 33a to 33d of the grating 31c is obtained by calculating the angle difference of the grating around the grating 31c to be obtained by A1 to A8. Then

[0053]

(Equation 4)

Is as follows. Then, the image processing apparatus 21 calculates the diagonal distortion amount DH and the angular distortion amount AH for each of the lattices 31 of the input reflection image of the mirror M, and stores them in the data memory 21b in correspondence with each of the lattices 31. . The diagonal distortion amount DH corresponding to each lattice 31 is shown in FIG. 7, and the angular distortion amount AH corresponding to each lattice 31 is shown in FIG.

In FIGS. 7 and 8, the value of "0" on both the vertical and horizontal axes is the center of the reflection image of the mirror M, and the side with the larger distortion in FIGS. FIG.
8 (right side in FIG. 8). The distortion amounts shown in the figure are each represented by [× 10 ⁴ ].

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

Then, the image processing device 21 compares the diagonal distortion amount DH obtained for each of the lattices 31 with a predetermined threshold value. This threshold is obtained in advance by an experiment and stored in the data memory 21b.

When the amount of diagonal distortion DH is smaller than the threshold value, it means that the distortion in the lattice 31 is smaller than that of the surrounding lattice 31. When the amount of diagonal distortion DH is larger than the threshold value, The distortion at 31 is the surrounding grid 31
Means greater. Then, the image processing device 21 joins the lattices 31 whose diagonal distortion amount DH is larger than the threshold value to determine a plurality (all as many as possible) of the shapes of the distortion portions 41 (determination of distortion portions). In this embodiment, the diagonal distortion amount DH is “0.012” (“1” in the drawing).
20 ") The above-mentioned lattices 31 are joined to determine the shape of the distorted portion.

Next, the image processing device 21 calculates the diagonal distortion amount D
H, the maximum diagonal distortion amount DHM among the distortion portions 41 determined by H
Select Further, the image processing device 21 determines the distortion unit 41 including the selected maximum diagonal distortion amount DHM as the maximum distortion unit 41a (selects the maximum distortion unit), and calculates the number of the lattices 31 included in the maximum distortion unit 41a. (Grid number calculation). Then, the image processing apparatus stores the calculated maximum diagonal distortion amount DHM and the number of grids in the data memory 21b. In FIG. 7, the maximum diagonal distortion amount DHM is "0.0392"("392" in the drawing), and the number of lattices of the maximum distortion portion 41a including the maximum diagonal distortion amount DHM is "55".

Then, as shown in FIG. 8, the image processing device 21 selects the maximum angular distortion AHM from the angular distortion AH of each lattice 31 in the maximum distortion section 41a, and selects the selected maximum angular distortion AHM. The quantity AHM is stored in the data memory 21b.
In FIG. 8, the maximum angular distortion AHM is “0.016”.
(“160” in the drawing).

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

When at least one of the maximum diagonal distortion amount DHM, the number of grids, and the maximum angular distortion amount AHM is larger than each threshold value, the image processing apparatus 21 determines whether the mirror M to be inspected has a larger size. It is determined that the distortion is large and defective, and the result of the determination 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 apparatus 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 determined to be rejected when at least one of 8 or more (“180” in the drawing) and the number of grids is “19” or more. Therefore, in the data shown in FIGS. 7 and 8, the number of grids is “55”.
Therefore, the image processing apparatus 21 determines that the mirror M, which is the inspection target that has acquired this data, is rejected.

As described above, according to the present embodiment,
The following effects are obtained. (1) Grating pattern 1 for mirror M to be inspected
8 is projected, the distortion of each grating 31 is calculated based on the image data of the grating pattern 18 reflected by the mirror M, and the distortion of the mirror M is detected. As a result, the detection accuracy at the central portion and the peripheral portion of the mirror M can be made the same, and the peripheral portion can be detected more finely than before.

(2) The image processing device 21 corrects the distortion of each of the gratings 31 forming the grating pattern 18 of the reflected image of the mirror M.
A diagonal difference D between diagonal lines 32a and 32b of the lattice 31;
Angle difference A between the sides 33a to 33d constituting the grid 31 and the axis
And ask. Then, the image processing device 21
The deviation of the diagonal difference D and the angle difference A of 1 was determined based on the diagonal difference and the angular difference of the lattices around the lattice 31, and the deviation was calculated as the diagonal distortion amount DH and the angular distortion amount AH of the lattice 31. As a result, the amounts of distortion DH and AH on the curved reflecting surface that change at a substantially constant curvature have small values. Therefore, it is possible to detect distortion not only on the plane reflecting surface but also on the curved reflecting surface.

(3) The image processing apparatus 21 determines whether or not the amount of diagonal distortion DH of each grid 31 is equal to or larger than a predetermined threshold value.
1 to form a distorted portion 41, and the distorted portion 41 having the largest number of lattices 31 constituting the distorted portion 41 is replaced by a maximum distorted portion 41 a
And The image processing device 21 sets the largest values of the diagonal distortion amount DH and the angular distortion amount AH of the grid 31 included in the maximum distortion unit 41a as the maximum diagonal distortion amount DHM and the maximum angular distortion amount AHM. Then, the image processing device 21 determines the maximum diagonal distortion amount DH
M, the number of lattices of the maximum distortion portion 41a, and the maximum amount of angular distortion AHM
When at least one of the mirrors is larger than a predetermined threshold value corresponding to each of them, 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 it can be determined whether the mirror M is acceptable.

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

(2) In the above embodiment, the grid pattern 18 is formed by the plurality of light emitting points 19 arranged in the horizontal and vertical directions, but the camera 13 reliably detects the intersection of the grid pattern 18. Any method may be used as long as it is possible. For example, the side surface 17a
Is formed of a transparent plate of acrylic or the like, 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 each light emitting point 19, and a laser, LED, halogen lamp, xenon is arranged on the optical fiber. The method may be implemented by using a method of guiding light from a lamp or the like, or directly disposing a laser, an LED, or the like at each of the light emitting points 19.

(3) In the above embodiment, the light emitting point 19 is formed by projecting light having a circular cross section. However, the light emitting point 19 may be formed in any shape as long as the intersection of the lattice pattern 18 can be reliably detected. May be implemented. For example, it can be formed in a cross shape, a polygon shape, a ring shape, or the like.

(4) In the above embodiment, the grid pattern 18 is projected by the light emitting points 19 provided at each intersection. However, 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 formed along two axes having an arbitrary angle and orthogonal to each other. Are arranged in a grid pattern 18
May be formed.

(6) In the above embodiment, the grid pattern 18 is a mesh formed by a group of parallel lines that are arranged at right angles in the horizontal and vertical directions and intersect at an arbitrary angle. It may be implemented as a mesh formed by a plurality of equally spaced parallel line groups. For example, a mesh of equilateral triangles formed by three equally spaced parallel lines intersecting at 60 ° may be used as a grid pattern, and a light emitting point 19 may be provided at the intersection 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 amount of lattice distortion.

(7) In the above embodiment, the distortion amount of the grid of interest 31c is calculated based on the grid of interest 31c and the eight surrounding grids. The number may be changed as appropriate to implement. For example,
The amount of distortion of the grid 31c may be calculated based on four grids, up, down, left and right, or 24 surrounding grids of the grid 31c of interest.

(8) In the above embodiment, the image processing apparatus 21 calculates the calculated maximum diagonal distortion amount DHM,
The number of grids 1a and the maximum amount of angular distortion 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 an external device,
The mirror M which becomes defective in the external device may be excluded from the transport device.

(10) In the above embodiment, the slider 1
Although an air-floating air slider with a linear motor is used in 4, a bearing-type slider may be used. (11) In the above embodiment, the image processing device 21
After obtaining the maximum diagonal distortion amount DHM, the maximum distortion portion 41a may be formed by combining continuous lattices including the maximum diagonal distortion amount DHM.

Although the embodiments of the present invention have been described above, technical ideas other than the claims that can be grasped from the embodiments will be described below together with their effects. (A) In the distortion inspection apparatus according to claim 3 or 4 , the projection unit is arranged on a side of the inspection target and has a lattice pattern formed on a side surface, and the projection panel has a lattice pattern on the inspection panel. Inspection system composed of a half mirror that projects light onto According to this configuration, it is possible to project the grid pattern on the entire surface of the inspection target.

(B) The distortion inspection apparatus according to claim 3 or 4 , wherein said image input means comprises a camera comprising a line CCD and a slider for horizontally moving the camera. According to this configuration, the number of pixels for input can be increased, and image data of the entire surface of the inspection target can be input with high accuracy.

In this specification, means and members according to the present invention are defined as follows. The lattice pattern means an imaginary mesh formed by a group of parallel lines intersecting at equal intervals, and is not limited to a mesh formed by a group of orthogonal parallel lines, but may be formed by a group of parallel lines crossing at an arbitrary angle. It also includes the formed network.

[0080]

As described above in detail, according to the present invention, it is possible to provide a distortion inspection method and a distortion 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 distortion inspection apparatus according to an embodiment.

FIG. 2 is a schematic side view of the distortion inspection apparatus 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 state of distortion.

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

6A is an explanatory diagram showing a diagonal difference between gratings, and FIG. 6B is an explanatory diagram showing an angular difference between gratings.

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

FIG. 8 is an explanatory diagram showing an angle difference distortion amount of each lattice.

FIG. 9 is a schematic front view of another distortion inspection apparatus.

FIG. 10 is a schematic side view of another distortion inspection apparatus.

[Explanation of symbols]

17: projection panel as projection means, 20: half mirror as projection means, 18: grid pattern, 13: camera as image input means, 31: distortion amount calculation means, diagonal distortion amount calculation means, angle distortion amount calculation Means, first selecting means, distortion portion forming means, lattice number calculating means, second selecting means,
Image processing device as determination means, M ... Mirror as inspection object.

Continuation of front page (56) References JP-A-7-83624 (JP, A) JP-A-1-165907 (JP, A) JP-A-60-200141 (JP, A) (58) Fields investigated (Int .Cl. ⁷ , DB name) G01M 11/00 G01B 11/16 G01B 11/24 G01B 11/30 101

Claims (4)

(57) [Claims] 1. A distortion inspection method for detecting distortion of an inspection object based on a reflection image from the inspection object, wherein a lattice pattern including a plurality of lattices is projected on the inspection object, and The deviation between the diagonal difference of each grating of the reflected grating pattern and the diagonal difference of the surrounding gratings
The difference is defined as the amount of diagonal distortion, and each grid is constructed with respect to the reference axis.
The difference between the angle difference between the formed sides and the angle difference
And strain amount, calculates a diagonal distortion amount and angle strain in the respective grid, each
A distortion inspection method for inspecting pass / fail of the inspection object based on a diagonal distortion amount and an angular distortion amount of a lattice . 2. The distortion inspection method according to claim 1, wherein a maximum diagonal distortion amount is selected from the diagonal distortion amounts, and a grid of the maximum diagonal distortion amount is included, and the diagonal distortion amount is predetermined.
The maximum strain that combines continuous lattices equal to or greater than the threshold
And calculating the number of lattices included in the maximum distortion portion, and calculating the maximum angle among the angular distortion amounts of the lattices included in the maximum distortion portion.
Degree distortion amount, the maximum diagonal distortion amount, the maximum angle distortion amount, and the number of lattices.
At least one of which is preset for each
Strain detection to determine whether it is greater than a threshold
Inspection method. 3. The inspection system according to claim 1 , wherein
What is claimed is: 1. A distortion inspection apparatus for inspecting distortion of an inspection object , comprising: projection means for projecting a lattice pattern onto the inspection object
And projected by the projection means and reflected by the inspection object.
Image input means for inputting a reflection image of a grid pattern, and each grid forming a grid pattern of the input reflection image
The deviation between the diagonal difference of
And the angles of the sides that make up each grid with respect to the reference axis
The deviation between the power difference and the angle difference of the surrounding grid is defined as the amount of angular distortion.
Distortion amount calculating means for calculating a diagonal distortion amount and an angular distortion amount of the lattice;
A strain inspection device provided with. 4. The distortion inspection apparatus according to claim 3, wherein a maximum diagonal distortion amount is selected from the diagonal distortion amounts.
And a grid of the maximum diagonal distortion amount , wherein the diagonal distortion amount is predetermined.
Of the maximum strain by combining
Means for forming a strained portion to be formed, and a grid number calculating means for calculating the number of grids included in the maximum strained portion
And the maximum angle among the angular distortion amounts of the lattice included in the step and the maximum distortion portion.
Selecting means for selecting the degree of distortion, and the first and second selecting means and the number of grids calculating means.
Large diagonal distortion, maximum angular distortion, and small number of grids
At least one of them is a preset threshold for each
And a judging means for judging whether the value is larger than the value.
Inspection equipment.