JP2006071512A - Three-dimensional measuring method and three-dimensional measuring apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the height position of a faulty part or the like in a transparent or semitransparent product at high speed. <P>SOLUTION: The photographing areas of two cameras 3, 4 installed with different angles are joined to simultaneously photograph a foreign body in a transparent or semitransparent object to be inspected W. The center of gravity of the foreign body on a screen of the cameras 3, 4 is captured by a storage of a computer 7. On the basis of the position information of the foreign body by the cameras 3, 4, the height position of the foreign body in the object to be inspected W is calculated through calculations using prestored installation angles of the cameras 3, 4, the thickness information of the object to be inspected W by a camera 5, or the like. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a three-dimensional measurement method and a three-dimensional measurement apparatus for photographing an object to be inspected using a plurality of photographing means and measuring the position of, for example, a defective portion in a product.

  Three-dimensional measurement methods generally used to measure the height direction of the object to be measured include triangulation method using laser displacement meter, confocal method, focusing method, and light cutting method using slit light. It has been.

  The triangulation type laser displacement meter has the feature that the position inspection can be performed with high accuracy and the response time of the inspection is fast, but the position that can be inspected is only one point where the spot of the laser beam is hit. In the inspection, the spot position is scanned to inspect the cross-sectional shape (see Patent Document 1). In this method, since the inspection time becomes very long, when detecting, for example, a defective portion in a product as an actual inspection device, the inspection efficiency is poor and cannot be used.

Further, as another method, there has been proposed a light cutting method in which slit light is irradiated on an object to be measured and an inspection is performed based on a deviation of the irradiated slit light (see Patent Document 2). However, from the viewpoint of the line-shaped light source width of the slit light to be irradiated, only information in the height direction on the line irradiated with light in a single captured image can be obtained. The slit light position of the light source must be scanned at equal intervals, which is also not suitable for detecting a defective portion in the product and the like in terms of apparatus cost and inspection efficiency.
Japanese Patent Laid-Open No. 11-83453 Japanese Patent Laid-Open No. 5-60524

  The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and measures the position in the height direction of a foreign object such as a defective portion in the inspection object at a high speed with respect to the inspection object. It is an object of the present invention to provide a three-dimensional measurement method and a three-dimensional measurement apparatus capable of performing the above.

  In order to achieve the above object, the three-dimensional measurement method of the present invention irradiates a transparent or semi-transparent object with illumination light, and can simultaneously photograph foreign objects in the object in the same cross section. A step of installing a plurality of photographing means at various positions, a step of simultaneously photographing the foreign matter in the inspection object by each photographing means, and obtaining position data of the foreign matter from the photographed image, and the position data and each photographing. And a step of calculating a height position of the foreign matter in the inspection object based on an installation angle of the means.

  The position of the foreign material in the height direction is measured by photographing the inside of the object to be inspected using a plurality of photographing means and performing digital processing.

  Since arithmetic processing is performed on the basis of image data from a single captured image that is simultaneously captured by a plurality of imaging means, it is possible to detect a defective portion or the like in a product at an extremely high speed.

  As shown in FIG. 1, the back surface side of the inspection object W on the stage 1 is irradiated with illumination light from the projection device 2 that is a light source, and the inspection object is simultaneously used using the cameras 3 and 4 that are imaging means from the front surface side. W is photographed, and the images of the cameras 3 and 4 are digitally processed. This imaging is performed by matching the imaging ranges of the cameras 3 and 4 with respect to an arbitrary position in the inspection object W.

  That is, two cameras 3 and 4 are used, and both cameras 3 and 4 are set at arbitrary points, and both cameras 3 and 4 simultaneously photograph the same position with respect to the object W, and the object to be inspected by the plurality of images. Based on the position information of the foreign matter in W and the installation angle of each camera 3, 4, the thickness information of the inspection object W by the thickness detection camera 5 that images the inspection object W from the side is used. Parameter setting and image processing are performed in the storage device and the processing device which is a calculation means, and information on the height direction of the foreign matter in the inspection object W is obtained. Then, the result is displayed on the display device 8.

  In this way, the imaging range of the plurality of imaging means is adjusted to an arbitrary position of the object to be inspected, the foreign matter in the object to be inspected as image data from different angles, and the difference in the position information of the foreign matter by the captured image data Because of the difference in the installation angle of the imaging means, when the measurement reference position is set to zero in the thickness axis direction, the sum of the absolute values of the differences between the position of the foreign matter in the inspection object obtained by the imaging means and the reference position is The parameters of the program are set so as to be approximately equal to the thickness of the inspected object measured in advance, and the height position of the foreign matter in the inspected object is measured by performing image processing.

  In order to match the imaging range of a plurality of cameras to an arbitrary point, it is necessary to consider both the installation angle of the plurality of cameras and the imaging range of each camera. That is, it has been found that it is not only necessary to match the imaging range of the camera as the imaging means to the object to be inspected, but there is an appropriate arrangement.

  Regarding the imaging range of multiple cameras, the position of the imaging range of each camera must be set to a position where the foreign object of the object to be inspected by the camera falls within the depth of field of all cameras. Therefore, it is necessary that the foreign matter in the inspection object enters the capturing area of each camera regardless of the height position of the inspection object.

  Therefore, the iris diaphragm can be adjusted, and the depth of field can be adjusted. For example, by using a lens whose depth of field can be adjusted to 0.3 to 0.5 [mm] as an objective lens of the camera. Thus, it is possible to capture the foreign matter in the inspection object as image data. Although the depth of field is set to 0.5 [mm] in this embodiment, the depth of field is not limited to this value as long as the object can be imaged.

  Next, the installation angles of the plurality of cameras are determined based on the relationship between the imageable range position of each camera and the depth of field. It should be noted that an optimum value is experimentally obtained for the relationship between the position of the range where a plurality of cameras can simultaneously capture an arbitrary point and the installation angle of each camera. The camera installation angle can be 1 to 89 ° (an angle other than 0 ° and 90 °), but preferably 15 to 60 ° from the relationship between the resolution and the depth of field.

  The apparatus in FIG. 1 includes a stage 1 that supports an object W to be inspected, a projection device 2, a camera (A) 3, a camera (B) 4, a camera (C) 5, lenses 6a to 6c, a storage device, and a processing device. This is a three-dimensional measuring device including a drive device 9 that controls the position of the computer 7, the display device 8, the stage 1, and the installation angle of the camera (A) 3, the camera (B) 4, and the like.

  Illumination light from the projection device 2 is projected as a shadow by a foreign substance inside the inspection object W, and is imaged by the two camera cameras (A) 3 and camera (B) 4.

  At this time, the camera (A) 3 and the camera (B) 4 are arranged so that the optical axes intersect each other at one arbitrary point and have an imageable range as a reference position. 7 is arranged so that the position can be set in the storage device 7. The arrangement angle can be set from 1 to 89 °, but a range of 15 to 60 ° is desirable from the relationship between resolution and depth of field.

  The reference position of the imageable range may be an arbitrary point, but in this embodiment, the inspected object W is set so that the depth of field of the lenses 6a and 6b can sufficiently cover the inside of the inspected object W. Set inside. In addition, the edge part of the gauge created with metal was set to the position of the lower end of the inspection object so that the imageable range position can be set to the internal position of the inspection object W.

  In order to measure the thickness of the inspection object W, the camera (C) 5 is installed in the lateral direction of the inspection object W. The installation angle of the camera (C) 5 is not particularly limited as long as the thickness of the inspection object W can be measured, but is set to 90 ° in the present embodiment from the viewpoint of measurement resolution.

First, as shown in FIG. 2, the width (thickness) X of the inspection object W on the screen of the camera (A) 3 displayed on the display device 8 and the inspection object W on the screen of the camera (B) 4 are displayed. The following relationship is established between the width (thickness) Y and the width (measured value of thickness) T of the inspection object W on the screen of the camera (C) 5.
| X | = T · sin θ ₁ (1)
| Y | = T · sin θ ₂ (2)

3 and 4, the separation distance x from the optical axis position 01, which is the position data of the center of gravity position of the foreign matter V on the screen of the camera (A) 3 displayed on the display device 8, the camera ( B) Separation distance y from the optical axis position 02, which is position data of the center of gravity position of the foreign substance V on the screen 4, and separation distance from the reference position 0 on the screen of the camera (C) 5 to the lower end of the inspection object W When the height position t _{0 of} the foreign object V from the reference position 0 and the height position of the foreign object V from the lower end of the object W are t, the following relationship is established. First, similarly to the above formulas (1) and (2), assuming that the components in the height direction of the position data x and y are t ₁ and t ₂ ,
x = t ₁ · sin θ ₁ (3)
y = t ₂ · sin θ ₂ (4)
From equations (3) and (4),
t ₁ = x / sin θ ₁ (5)
t ₂ = y / sin θ ₂ (6)
Since the camera (A) 3 and the camera (B) 4 are capturing the same foreign object V, the following two equations are established, where S is the horizontal deviation from the reference position 0.

t ₀ = −S · tan θ ₁ + (x / sin θ ₁ ) (7)
t ₀ = S · tan θ ₂ + (y / sin θ ₂ ) (8)
From equations (7) and (8),

また、被検査物Ｗ内の異物Ｖの高さ位置ｔは以下の式で表わされる。

Further, the height position t of the foreign matter V in the inspection object W is expressed by the following expression.

t = t ₀ + a
(10)
From equations (9) and (10),

That is, using the position data x and y in the image shown in FIG. 4 and the installation angles θ ₁ and θ _{2 of the} camera (A) 3 and camera (B) 4 and the height a of the reference position 0, the expression (11) By performing the calculation, the height position t of the foreign matter V in the inspection object W can be obtained.

  Next, the operation will be described with reference to FIG. In step 1, the projection device 2 is supplied with power by a power source and a control unit (not shown) and emits a uniform amount of visible light. The spot size was set to about φ10 mm from the viewpoint of lens magnification and camera field of view. In step 2, the stage 1 is moved to irradiate a predetermined part of the inspection object W with the spot light. In step 3, when spot light is irradiated onto the inspection object W, it becomes a shadow by the foreign matter V, passes through the lenses 6a and 6b, forms an image, and is taken as an image into the camera (A) 3 and the camera (B) 4. It is. Each of the lenses 6a and 6b uses a high-resolution macro zoom lens using a perfocal optical system and uses an iris diaphragm function and an adjustable light quantity. We selected one that could form an image accurately without waking up.

In step 4, the captured image is transferred to the storage device and processing device of the computer 7 as an electrical signal, and stored in the storage device as image data. Thereafter, the image data is transferred to a processing apparatus, and image processing is performed to extract position information (center of gravity position) of an image formed by the foreign matter V in the inspection object W. In that case, settings such as the magnification of each lens 6a, 6b, the installation angles θ ₁ , θ _{2 of} each camera 3, 4 and the reference position of the imageable range are registered in advance in the processing device. In step 5, the camera (C) 5 installed in the horizontal direction measures the thickness T of the inspection object W, which is a transparent or translucent plate-like object, and in step 6, the camera installation angles θ ₁ , θ ₂ and The height position of the foreign matter V based on the position data x, y which is the position information of the foreign matter V extracted by the cameras 3 and 4 and the height a of the reference position 0 obtained from the thickness information obtained by the camera 5. t is calculated.

  Further, the entire inspection object W can be inspected by interlocking with the driving device 9 and controlling the stage 1 according to the set measurement resolution and sequentially changing the inspection position.

(Concrete example)
Measurement was performed with the installation angles of the two cameras A and B set to θ ₁ and θ ₂ of 30.0 °. The object to be inspected at that time was selected as a sample with a foreign object embedded in the product. It should be noted that the actual position of the defective portion in the height direction is confirmed to be 300 μm from the lower end of the product by the conventional triangulation laser displacement meter.

  When the imageable range was set to the lower end position of the product and inspected by the cameras A and B, the height position of the foreign matter, that is, the defective portion was 300 μm from the lower end position of the product.

  In this embodiment, since it is possible to measure the imaging range 1.58 × 1.36 [mm] in one captured image, the height on the line irradiated with the light source in one captured image is high. The measurement speed is improved compared to the optical cutting method that can only obtain the information of the direction.

  From this, it can be judged that the inspection accuracy is equal and that it is possible to measure at high speed with respect to the measurement, so that the three-dimensional measurement in one embodiment can be measured at a higher speed than the measurement by the conventional example. .

It is a figure explaining the three-dimensional measuring apparatus by one Example. It is a figure which shows the method of calculating the parameter regarding the thickness information of a to-be-inspected object. It is a figure which shows the method of calculating the height position of the foreign material in a to-be-inspected object. It is a figure explaining the image data of each camera. It is a flowchart which shows a three-dimensional measuring method.

Explanation of symbols

1 Stage 2 Projector 3 Camera A
4 Camera B
5 Camera C
6a to 6c Lens 7 Computer 8 Display device 9 Drive device

Claims (2)

  A step of irradiating a transparent or semi-transparent inspection object with illumination light, and installing a plurality of imaging means at positions where foreign matter in the inspection object is in the same cross section and can be simultaneously imaged; and each imaging means The foreign matter in the inspection object is simultaneously imaged by the step of obtaining the position data of the foreign matter from the captured image, and the position of the foreign matter in the inspection object based on the position data and the installation angle of each imaging means. And a step of calculating a height position.   A light source that illuminates a transparent or translucent object to be inspected with illumination light, a plurality of photographing means for photographing a foreign object in the object to be inspected by transmitted light of the illumination light, and an image of the foreign object by each photographing means And calculating means for calculating the height position of the foreign matter based on the installation angle of each imaging means, and the plurality of imaging means are mutually connected at arbitrary positions in the inspection object. A three-dimensional measuring apparatus characterized in that the optical axes are crossed and the respective imaging ranges are photographed together.

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