JP3514122B2 - Surface defect inspection equipment - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface defect inspection apparatus capable of detecting defects with uniform accuracy regardless of whether the surface to be measured is a flat surface or a curved surface.

[0002]

2. Description of the Related Art As a conventional surface defect inspection apparatus, there are JP-A-8-285559 and JP-A-9-7998.
There is one disclosed in Japanese Patent No. These are related to a device that projects a stripe pattern on a surface to be inspected, captures the stripe pattern in a CCD camera, performs image processing, and detects a defect based on the processing result.
Even if the surface to be inspected is inclined or curved, it is devised so that the detection accuracy of defects does not decrease.

[0003]

However, in such a conventional defect inspection apparatus, the inclination of the surface to be inspected,
The stripe pattern taken into the CCD camera is made uniform based on the curved state, that is, the stripe pitch is made uniform. However, the shape of the surface to be inspected varies greatly depending on the vehicle model and part, so the stripe pattern Even if the pitch can be made uniform, the number of stripes taken in by the CCD camera is often different, so that the defect detection accuracy cannot be said to be completely stable. This is because it is difficult to detect defects located at the edges of the stripes, and thus the detection accuracy decreases as the number of stripes increases.

The present invention has been made in order to solve such a conventional problem, and the number of stripes taken into the CCD camera is always constant so that the measured surface is a flat surface or a curved surface. It is an object of the present invention to provide a surface defect inspection apparatus capable of detecting defects with uniform accuracy regardless of whether the surface defect inspection device is a surface defect inspection device.

[0005]

The present invention for achieving the above object is configured as follows.

According to the first aspect of the invention, a plurality of lights are arranged in a row.
Stripe pattern forming means for forming a stripe pattern on the surface to be inspected by turning on and off in units, stripe pattern input means for inputting a stripe pattern reflected on the surface to be inspected, and stripe pattern input means The number of stripes from the entered stripe pattern
The lights of the stripe pattern forming means are turned on and off so that the number of the extracted stripes becomes a constant number.
It has a control means for controlling in a column unit .

The invention as defined in claim 2 is as set forth in claim 1.
In the surface defect inspection device of
Means, illumination means and an arcuate illumination arranged in a plurality of rows parallel tunnel, the lights of illumination of said illumination means and an illumination control means for controlling the column-by-column basis, on the surface to be inspected It is characterized in that it forms a stripe pattern.

According to a third aspect of the present invention, in the surface defect inspection apparatus according to the second aspect, the illumination constituting the illumination means is a plurality of LEDs arranged in an arch shape. To do.

The invention as defined in claim 4 is as set forth in claim 1.
In the surface defect inspection device of
Means comprises a liquid crystal shutter capable of the width and pitch of the stripes freely changed, and irradiating means for irradiating the stripes formed by the liquid crystal shutter on the inspected surface, stripes on the surface to be inspected Forming a pattern
Is intended, said control means, so that the number of stripes is constant number, and controls the pitch and width of stripes formed in the liquid crystal shutter.

[0010]

The present invention constructed as described above has the following effects for each claim.

According to the first aspect of the invention, since the number of stripes input by the stripe pattern input means is set to a fixed number, the surface to be inspected may be flat but curved. However, the number of stripes is always the same, and it becomes possible to detect defects in a stable state. Therefore, it becomes possible to detect defects with uniform accuracy.

The inventions described in claim 2 and claim 3 are
The number of stripes is set to a constant number by controlling the lighting of the illumination means in a tunnel shape by arranging a plurality of arch-shaped illuminations in parallel in each column, so that the number of stripes is constant. In addition to the effect similar to the effect, the number of stripes can be made constant by a simple control of controlling lighting.

According to the fourth aspect of the present invention, since the number of stripes is made constant by changing the width and pitch of the stripes of the liquid crystal shutter, in addition to the same effect as the first aspect, irradiation of the stripes is performed. Can be performed with a very small device.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram of a surface defect inspection apparatus according to the present invention. A lighting device 10 as a lighting unit shown in the figure has a plurality of lights arranged in a line to form an arch 15, and a plurality of lights are arranged in parallel in a tunnel shape (about 1.
5 m). As shown in FIG. 2, high-intensity LEDs 17 are arranged in a line in this arch 15 without a gap, and a reflecting plate is provided on the back side of the LEDs 17. The arches 15 are arranged side by side through a shield plate so as not to allow the illumination light of the adjacent arches 15 to enter (to improve the contrast of stripes and to make the black and white boundaries clear) and to form a tunnel. The illuminating device 10 is formed. When the LED of only one arch 15 is turned on, a stripe having a width corresponding to the width of the arch is reflected on the painted surface of the vehicle body. Therefore, the width of the stripe can be adjusted by the number of lighting columns of the arch.

The painted vehicle body will pass through the interior of the illuminating device 10. The illuminating device 10 is equipped with a CCD camera 20 as a stripe pattern input means for inputting a stripe pattern reflected on the vehicle body. There is. This C
The stripe image from the CD camera is processed by the image processing device 30.
Sent to. Although only one CCD camera is shown in the drawing, actually, a plurality of CCD cameras are provided corresponding to the inspection site.

The image processing apparatus 30 performs preprocessing for extracting a defect based on the input stripe image.

The host computer 40 functions as a control means, and a measurement start signal of a measurement start Ls (limit switch) provided on the conveyance line of the vehicle body, a line speed of the conveyance line, and the image processing device 30.
Based on the image processing result from, the width of the stripes, specifically, the stripe width, specifically, so that the number of stripes captured by the CCD camera 20 becomes constant (so that the specified number).
The lighting of each column of the lighting device 10 is calculated, and the result is output as a stripe width command. Further, a defect on the coated surface is extracted from the image processing result of the image processing device 30, and the result is displayed or printed on the monitor 60 or the printer 70.

The illumination controller 50 functions as illumination control means, and receives a stripe width command from the host computer 40 to turn on / off the illumination of each arch 15 constituting the illumination device 10 for each column. It is a thing. The illumination device 10 and the illumination controller 50 constitute a stripe pattern forming means.

FIG. 3 is an operation flowchart of the surface defect inspection apparatus according to the present invention. The operation of the device of the present invention will be described in detail below with reference to this flowchart and FIGS.

In this flowchart, S1 to S
In step 5, as shown in FIG. 4, the shape of the inspection surface changes as the vehicle body is transported, but the number of stripes captured by the CCD camera should be constant regardless of the change in shape. Then, the process of controlling the lighting of the illumination device 10 is performed.

For example, as shown in FIG. 5, when the inspected surface of the vehicle body is flat, the CCD camera inputs a stripe pattern having a width as shown in FIG. Then, the width of the stripe pattern captured by the CCD camera in its field of view becomes narrower than that when the surface to be measured is flat. As the curvature of the curved surface becomes smaller, many thin striped patterns such as lines appear.
As described above, when the number of stripes is increased, the boundary line between the defect and the stripe is unified, and the possibility that the defect does not appear as an isolated point increases. In the processing of the above steps, such a problem is eliminated.

In step S6, in parallel with the above process, a process for extracting defects on the painted surface based on the image picked up by the CCD camera is performed. The time required for one processing of this flowchart is about 60 msec.

First, when the vehicle body after painting is conveyed by the conveying line and the measurement start Ls is hit, the host computer 40 instructs the illumination controller 50 to specify a stripe width (for example, 20 of the arch 15 when the surface to be coated is flat).
A command to repeat lighting and extinguishing for each column) is output, and the lighting device 10 lights all the LEDs 17 forming the arch 15 at lighting intervals based on this command. The CCD camera 20 inputs the image including the stripe pattern formed by the lighting device 10 and projected on the painted surface of the vehicle body, and sends it to the image processing device 30 (S1).

The image processing apparatus 30 performs binarization processing and differentiation processing on the input image and sends the image to the host computer 40. The host computer 40 extracts the number of stripes from the image after image processing sent from the image processing apparatus 30 (S2), and calculates the stripe number ratio. This stripe number ratio is obtained by dividing the number of extracted stripes on the screen by a predetermined number of prescribed stripes. For example, if the number of stripes on the screen is 8 and the prescribed number of stripes is 5,
The stripe number ratio is 1.6 (S3).

Next, the host computer 40 calculates the commanded stripe width. This stripe width is calculated by multiplying the current stripe width (illumination ratio) by the stripe number ratio calculated in the previous step. For example, if the lighting device 10 is composed of 200 rows of arches, in the above example, the lighting ratio is 50% because lighting and turning off are repeated every 20 rows. When this is multiplied by the stripe count ratio of 1.6, the commanded stripe width becomes 80%. Therefore, the host computer 4
0 indicates the lighting controller 50 to the arch 1 of the lighting device 10.
5 is instructed to repeat the pattern of turning on 32 columns (stripe width) and turning off 8 columns (stripe pitch), and the illumination controller 50 controls the illumination of the illumination device by this pattern (S4). S5).

In parallel with this process, a defect detection process similar to the conventional one is performed. That is, based on the image that has been binarized or differentiated by the image processing device 30, a process for detecting an isolated point and determining this as a defect is performed (S6). The above process is repeated until the measurement of all the measurement points for one vehicle body is completed (S7).

As described above, in the surface defect inspection apparatus of the present invention, the number of stripes imaged by the CCD camera 20 can always be constant regardless of the shape of the surface to be inspected (the surface to be inspected having a large curvature). The number of lighting rows is controlled so that the width of the stripe becomes narrower, and the number of lighting rows is controlled so that the width of the stripe becomes wider on the surface having a small curvature.) The shape of can be flexibly accommodated. In addition, stable accuracy of defect detection can be maintained.

As described above, in the embodiment of the present invention, the LED which is used for the illumination which constitutes the illuminating device 10 has been exemplified, but the present invention is not limited to this. For example, an incandescent lamp or a fluorescent tube can be used. .

FIG. 7 shows a second embodiment of the device of the present invention. In this embodiment, a stripe image is projected on a screen 90 functioning as an irradiation means by a liquid crystal projector 80 having a liquid crystal shutter capable of freely changing the width of the stripe, and the stripe image is reflected on the surface to be coated of the vehicle body. The image obtained is configured to be captured by the CCD camera 20.

Other configurations are not shown because they are the same as the configurations shown in FIG. 1, but in the host computer, CC
The pitch and width of the stripes formed on the liquid crystal projector 80 are controlled so that the number of stripes captured by the D camera 20 is constant. The pitch and width are calculated in the same way as in the first embodiment.

In another embodiment, a stretchable striped sheet provided so that the stripes are projected on the surface to be inspected by the backlight is constructed so that it can be expanded and contracted by a motor, and the stripes projected on the CCD camera are displayed. The stripe sheet may be expanded and contracted by controlling the motor so that the number is constant.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a surface defect inspection apparatus according to the present invention.

FIG. 2 is a partially enlarged view of the lighting device shown in FIG.

FIG. 3 is an operation flowchart of the apparatus shown in FIG.

FIG. 4 is a diagram for explaining the operation of the device of the present invention.

FIG. 5 is a diagram for explaining the operation of the device of the present invention.

FIG. 6 is a diagram for explaining the operation of the device of the present invention.

FIG. 7 is a schematic configuration diagram of another embodiment of the surface defect inspection apparatus according to the present invention.

[Explanation of symbols]

10 ... Lighting device, 15 ... Arch, 20 ... CCD camera, 30 ... Image processing device, 40 ... Host computer, 50 ... Lighting controller.

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01B 11/30 G01N 21/89

Claims (4)

(57) [Claims] 1. A plurality of lights are turned on and off in units of columns.
And stripes forming means for forming a stripe pattern on the inspected surface by the a stripe pattern input means for inputting a stripe pattern is reflected on the inspected surface, Stra entered by the stripes input means
A control means for extracting the number of stripes from the stripe pattern , and controlling the lighting and extinguishing of the illumination of the stripe pattern forming means on a column-by-column basis so that the number of the extracted stripes becomes a constant number. A surface defect inspection apparatus having. 2. The stripe pattern forming means comprises a lighting means in which a plurality of columns of arch-shaped lighting are arranged in parallel to form a tunnel shape, and a lighting control means for controlling lighting of the lighting means in units of columns. has, serial said to claim 1, characterized in that to form a striped onto the surface to be inspected
On-board surface defect inspection system. 3. The surface defect inspection apparatus according to claim 2, wherein the illumination constituting the illumination means is a plurality of LEDs arranged in an arch shape. Wherein said striped forming means, chromatic liquid crystal shutter capable of the width and pitch of the stripes freely changed, and irradiating means for irradiating the stripes formed by the liquid crystal shutter on the surface to be inspected The above
Is intended to form a striped onto the test surface, wherein the control means includes a feature that the number of stripes to be constant number, controls the pitch and width of stripes formed in the liquid crystal shutter The surface defect inspection apparatus according to claim 1 .