JPH01227910A - Optical inspection device - Google Patents

Abstract

PURPOSE:To facilitate shape inspection by irradiating the curved surface of a body to be measured with line light from slantingly above and forming a light irradiation image similar to the arcuate shape of the curved surface. CONSTITUTION:When the curved surface 1a of the body 1 to be measured is irradiated with the line light 10a from slantingly above, the light irradiation image which cuts the curved surface 1a slantingly is formed on the curved surface 1a. This light irradiation image is detected by a photoelectric sensor 11 and applied to a signal processing means 13. Consequently, the signal is converted into a binary image wherein the curved surface shape is reflected and its binary image pattern is compared with a normal reference curved surface pattern to decide whether or not the curved surface 1a has a defect due to excessive cutting. Thus, the light irradiation image is formed on the curved surface 1a by the light cutting method of the line light 10a and executed the picture processing of the light image pattern to decide the curved surface shape, so the shape inspection is facilitated, the picture processing is speeded up, and the cost the processing system is reducible.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Industrial Application Field The present invention relates to an optical inspection device for optically inspecting the surface shape of an object to be inspected, and in particular for inspecting a processed surface finished into a curved shape. Related to optical inspection equipment.

B. Prior art An example of an object to be inspected having an arcuate surface is one in which one side of the object 1 to be inspected, which has a rectangular parallelepiped shape, is cut into an arcuate curved surface 1a, as shown in FIG. A shape inspection system determines whether or not this curved surface 1a has been processed into a regular size and shape.

By the way, in finishing machining of such a curved surface 1a, due to abnormal cutting feed of the cutting tool, etc., the top part (the hatched part) of the curved surface 1a may be cut more than necessary, as shown in FIG. 10.

Conventionally, a system shown in FIG. 11 or 12 is known as a system for optically inspecting the shape of an object to be inspected 1 having an arcuate surface as described above.

FIG. 11 shows that a laser or other light source 2 irradiates a curved surface 1a of an object 1 with a spot of light, and the reflected light is detected by a position sensor 3. Position sensor 3 and curved surface 1a utilize the fact that the output voltage differs depending on whether reflected light is received.
Find the relative distance a between the upper irradiation lights, and from this calculate the curved surface 1 t
The shape is inspected by measuring the shape of l.

In addition, FIG. 12 shows that the curved surface 1a of the object to be inspected 1 is uniformly irradiated by a plurality of light sources 4, the light irradiated surface is imaged by a television camera 5 placed on one side of the curved surface 1a, and the imaged signal is obtained. It is processed into a binary image or the like by a processing circuit (not shown), and from this processed image, the shape of the curved surface 1d, that is, the presence or absence and width of an over-cut portion as shown in FIG. 1O is detected.

C0 Problems to be Solved by the Invention In the conventional shape inspection method shown in FIG. 11, the inspection accuracy is improved because the spot light and the position sensor 3 are used to measure each point. It takes a lot of time to test and is not practical.

In addition, in the conventional shape inspection method shown in FIG. 12, the shape is determined from the image signal obtained by imaging the uniformly illuminated curved surface 1a with the television camera 5, so it is difficult to obtain a clear image. There is a lack of clarity in distinguishing images between a normal part of a single curved surface and a defective part due to over-cutting, and the processing of these images becomes extremely complex, increasing the system cost of the image processing device and reducing the reliability of shape inspection. There is also the problem of low gender.

There is also a method of measuring the shape of the curved surface 1a by a contact method, but this method takes a lot of time to inspect the shape and has problems such as damaging the object 1 to be inspected.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide an optical inspection device that can easily inspect the shape of a curved surface at low cost.

Means for Solving the D0 Problem FIG. 1 is a claim correspondence diagram corresponding to the claim of the optical inspection apparatus of the present invention.

In step 1, the linear light source 10 irradiates the object 1 to be inspected with line light 10a from diagonally above at a predetermined irradiation angle O to generate a light irradiation image that cuts the curved surface 1a of the object 1 obliquely. .

For example, a two-dimensional sensor is used as the photoelectric sensor 11, and two-dimensionally detects a light irradiation image 12 generated on the curved surface 1a by irradiation with the line light 10a.

The signal processing means 13 processes the light irradiation image 12 detected by the photoelectric sensor 11 into a binary image necessary for inspecting the shape of the curved surface 1a, and converts this binary image pattern (detection pattern) into a normal reference curved surface. The presence or absence of defects is determined by comparing with the pattern.

When the E1 action line light 10a and the curved surface 1a of the object to be inspected 1 are irradiated from an upward oblique direction, a light irradiation image is generated on the curved surface la, and this light irradiation image is detected by the photoelectric sensor 11 (processing a). By adding it to the means 13, it is converted into a binary image reflecting the curved surface shape, and by comparing and collating this binary image pattern with a normal reference curved surface pattern, the curved surface 1a is
Determine whether there is a defect due to excessive cutting.

Therefore, in the present invention, a light irradiation image is generated on the curved surface 1a by the light cutting method using the line light 10a, and this light image pattern is image-processed to determine the shape of the curved surface, so that shape inspection is possible. It is simple, and it is also possible to speed up image processing and reduce the cost of the processing system.

F. Embodiment 1 First Embodiment A first embodiment of the present invention will be described with reference to FIGS. 2 to 7.

FIG. 2 is an overall configuration diagram of a first embodiment of an optical inspection apparatus to which the present invention is applied, and the same parts as in FIG. 1 will be described with the same reference numerals.

In FIG. 2, the linear light g10 is on the side opposite to the moving direction of the object 1 to be inspected, which is transported in the direction of the arrow by the conveyor 15, and is tilted forward at a desired angle to the curved surface 1a of the object 1 to be inspected. On the other hand, at a desired irradiation angle O (for example, 30 degrees), the line light 10a
A slit plate 101 that generates
The light source 102 is located behind the slit plate 101 and is placed opposite to a transparent slit 101a for producing linear light formed horizontally on the slit plate 101.

The two-dimensional sensor 11 is a CCD (Charge Coupon).
This camera is composed of a solid-state camera or a television camera in which devices such as pledDevice are two-dimensionally arranged, and is placed above the object to be inspected 1, facing the part of the light irradiation image formed on the curved surface la of the object to be inspected. The peripheral area including the irradiation image is imaged. A two-dimensional image may be formed by using a one-dimensional sensor and moving it relative to the test piece 1.

The signal processing circuit 13 that takes in the video signal from the two-dimensional sensor 11 receives the digital signal from the A-D conversion circuit 131 and the A-D conversion circuit 131 that converts the analog signal from the two-dimensional sensor 11 into a digital signal. An image processing circuit 132 that processes a binary image reflecting the curved shape of the inspection object 1, and a display device W114 such as a CRT that processes this binary image pattern.
The display control circuit 133 for displaying the data and the data arrangement state on the coordinates corresponding to the light irradiation image are obtained from the binarized image pattern data stored in the memory 132a in the image processing circuit 132, and this and the data arrangement state in the memory 134a are calculated. A determination processing circuit 1 that determines whether or not there is a defect in the curved surface 1a of the detection pattern by comparing and collating the normal reference curved surface pattern data stored in the
It is composed of 34.

Further, in FIG. 2, 16 is a position detection device for detecting the inspection start position of the inspected object 1 transferred by the conveyor 15, and a light source 16a and a light receiving element 16b are opposed to each other with the conveyor 15 in between. A light source 16a
When the light from the light receiving element 16b is blocked by the object 1 to be inspected, the inspection of the object 1 to be inspected is started by a signal from the light receiving element 16b.

Next, the inspection operation of this embodiment configured as described above will be explained.

When the inspection object 1 placed on the conveyor 15 in the state shown in FIG. 2 is transferred in the direction indicated by the arrow by the operation of the conveyor 15, and the light source 16a blocks the light from the light receiving element 16b, the inspection system starts the inspection. After entering the mode, as the object 1 to be inspected moves in the direction of the arrow A, the two-dimensional sensor 11 detects the portion of the curved surface 1a illuminated by the line light 10a at predetermined time intervals, and the detected part is input into the signal processing circuit. Then, predetermined image processing and curved surface shape determination processing are executed.

Here, as shown in FIG. 9, the binary image pattern of the normally processed curved surface 1a becomes as shown in FIG. 3, and as shown in FIG. 10, the top of the curved surface 1a is shaved. A binarized image pattern when there is a defect due to overcrowding is shown in FIG.

In FIGS. 3 and 4, a white portion 30 corresponds to the light irradiation image formed on the curved surface la by irradiation with the line light 10a, and a hatched portion 31 corresponds to an area not irradiated with the line light 10a. .

As is clear from FIGS. 3 and 4, there is a difference between the height 81 and Q3 of the obtained curved surface pattern image between the normal case and the defective article.

The reason for this is that, as shown in FIG.
When the apex level of the curved surface 1a falls as shown by the broken line due to a defect such as overcutting, the irradiation position of the line light 10a becomes P
It changes from point to Q point. This is because a difference Δt occurs in the height of the curved surface portion due to excessive cutting. As a result, a difference in Δ is generated in the direction of arrow A in FIG.

This distance ΔQ is, as shown in FIG. 5, ΔQ=Q knee Q,
=Δj/tanθ. Therefore, by determining nl and Q shown in FIG. 3 or 4, the shape of one curved surface 1a can be determined.

An example of an image processing method for determining Ql and Q is shown in FIGS. 6 and 7. The binarized image after being detected by the two-dimensional sensor 11 and image-processed by the signal processing circuit 13 is usually X
, are treated as ixj dot data in the Y direction.

In this case, for each of the ixj dot data, a signal of a certain level or higher that is irradiated with the line light 10a is set to "H".
As a result, the image pattern captured by the two-dimensional sensor 11 and binarized becomes as shown in FIG. (the portion corresponding to the light irradiation image 12), this pattern data is stored in the memory 132a of the image processing circuit 132.

Then, in the determination processing circuit 134, the memory 132a
The pattern data within is scanned in the X direction from j=l, 1==1st, and the position where 118 II is first found. For example, as shown in Fig. 7, if area ■ (assuming these coordinates are Ill J) is the first 'H'', then (lx+1+jj, (xl-1+j+1)
, (1x+J+1), (j+1.j+1) °
'H' is checked.Then, the area ■ becomes 1.
1 HII, and then using the same method, it is found that the region (3) l■, . . . is II H11. In this way, the entire memory area in which the detection pattern data is stored is scanned to find the coordinates of the data that is LL HII. At this time, II H+
If the last coordinate that becomes 1 is (in, jn), then the length of the curved surface shape in the Y direction is the length of the coordinate (jn-j) (
(number of pixels).

In this case, if the length of each coordinate value (pixel) is δ, then J
The value is n Jx=Qx (orQ2)/δ. Therefore, in the determination processing circuit 134, the values of Ω and /δ as normal values are stored in the memory 134a in advance, and the Q obtained from this and the pattern of the actually detected curved surface is
It is determined whether or not the curved surface 1a of the object 1 to be inspected has a defect due to excessive cutting or the like.

In this way, in this embodiment, the curved surface 1 of the object l to be inspected is
A is irradiated obliquely from above with the line light 10a to produce a light irradiation image similar to the arc shape of the curved surface 1a, so the shape of the curved surface 1a can be clearly captured, and accordingly, the shape of the curved surface 1a can be clearly captured. Determination of the presence or absence of a defect on a curved surface becomes accurate, and the binarization process and determination process become easy, system cost is reduced, and the reliability of inspection is not impaired.

In the above-mentioned embodiment, the curved surface 1a of the object to be inspected 1 protrudes outward in an arc shape. However, the curved surface to be inspected may be curved inwardly, or It is also possible to inspect the angularly protruding parts.

-Second Embodiment- In the above-mentioned embodiment, the line light 10a directed toward the object 1 to be inspected is
We have explained the case where the irradiation angle θ is fixed constant and the same inspection object 1 is inspected, but if the irradiation angle θ is fixed,
When inspecting a mixture of inspection objects 1 with different curved surfaces 1a such as R, the light irradiation image of the curved surface 1a cannot be accommodated within the specific window detected by the two-dimensional sensor 11, and the image pattern to be inspected is missing. may occur.

FIG. 8 shows another embodiment of the present invention in which the irradiation angle θ of the line light can be changed according to the curved surface 1a of the object to be inspected 1 in order to solve the above-mentioned problems. .

In FIG. 8, the linear light source 10 is connected by an arrow B
A rotary drive device 17 such as a pulse motor is connected to the shaft 16, and by operating this rotary drive device 17, the curved surface 1a of the object 1 to be inspected is irradiated with the line light 10a. The angle θ can be changed.

In addition, a two-dimensional sensor 11 disposed above the object to be inspected 1 is provided with an image determination circuit 1 that determines whether the light irradiation image of the curved surface 1a falls within a predetermined specific window.
A control circuit 19 for controlling the rotary drive device 17 is further connected to the image determination circuit 18 .

In the system configured as described above, prior to actual shape inspection, first, the linear light source 10 is activated and the linear light 10a is
is irradiated onto the inspection object l on the conveyor IS, and in this state is passed through the detection area of the two-dimensional sensor 11 by the conveyor 15. At this time, the image determination circuit 18 determines whether the image has a size that fits within a predetermined specific window, and directs the linear light g10 in the direction of arrow B so that the image fits within the specific window. to change the irradiation angle θ. Once the beam is set at an illumination angle O suitable for inspecting the shape of the curved surface 1a, the system shown in FIG. 2 moves to actual shape inspection. Note that 1 image determination circuit 1
8 is incorporated in the signal processing circuit 13 shown in FIG.

In the above, the image determination circuit 18 determines the difference in the curved surface 1a and changes the direction of the linear light source 10. , the width and length may be measured using another optical sensor, and the direction of the linear light source 10 may be changed based on the measurement results.

Furthermore, in the above embodiment, the linear light source 10 is connected to the slit plate 1.
01 and the light source 102 was explained,
However, the light source is not limited to this, and the type of light source is not limited to an incandescent lamp, but a laser beam or the like may also be used. For example, the laser spot can be scanned in the width direction of the object to be inspected using a rotating polygon mirror or the like, or the laser beam can be converted into line light using a cylindrical lens.

Furthermore, in the embodiment, the case where the inspected object 1 is moved is described, but the linear light source 1o and the two-dimensional sensor 1
1 may be moved integrally parallel to the curved surface 1a.

G0 Effects of the Invention According to the present invention, the curved surface of the object to be inspected is irradiated obliquely from above with line light to generate a light irradiation image similar to the arc shape of the curved surface, so that the curved surface shape can be detected by a two-dimensional sensor. This makes it easier to process into a binary image, and it also makes it possible to accurately determine the presence or absence of defects on curved surfaces, reducing system costs for curved surface inspection. , the reliability of curved surface inspection can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a diagram corresponding to the claims of the optical inspection apparatus of the present invention. FIG. 2 is an overall configuration diagram of a first embodiment to which the present invention is applied. FIGS. 3 and 4 are explanatory diagrams showing curved image patterns in the first embodiment. FIG. 5 is an explanatory diagram showing the principle of curved surface inspection in the first embodiment. FIG. 6 and FIG. 7 are explanatory diagrams showing an example of the shape measurement of a curved surface in the first embodiment. FIG. 8 is a configuration diagram showing a second example in which the irradiation angle θ can be adjusted according to the present invention. FIG. 9 is a perspective view showing an example of an object to be inspected. FIG. 10 is a perspective view of an object to be inspected that has a defect. FIG. 11 and FIG. 12 are schematic configuration diagrams showing a conventional optical inspection device. 1: Inspection object 1a: Curved surface 10: Linear light source 10a Ni-line light 11: Two-dimensional sensor 12: Light irradiation image 13: Signal processing circuit

Claims (1)

[Claims] A linear light source that irradiates the object to be inspected with line light from diagonally above at a predetermined irradiation angle to create a light irradiation image that cuts the curved surface of the object diagonally, and irradiation with the line light from this linear light source. A photoelectric sensor detects the light irradiation image on the curved surface, processes the light irradiation image detected by this photoelectric sensor into a binary image necessary for inspecting the shape of the curved surface, and converts this binary image pattern into What is claimed is: 1. An optical inspection device comprising: signal processing means for determining the presence or absence of a defect by comparing the pattern with a normal reference curved surface pattern.