JP2897443B2 - Surface condition inspection method and 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 surface inspection method and apparatus for inspecting a surface defect such as a coating defect by irradiating a surface to be inspected with light and detecting the reflected light.

[0002]

2. Description of the Related Art Conventionally, the inspection of the painted state of a painted vehicle body in an automobile manufacturing line or the like has been performed by visual inspection of an operator. However, it is necessary to accurately inspect minute paint defects on the surface of the vehicle body. Was difficult, and a heavy burden was imposed on the operator to find it completely. In order to reduce the burden on the operator, see, for example, JP-A-62-23.
As shown in No. 3710, a surface to be inspected is irradiated with laser slit light, the reflected light is projected on a screen of a detecting means, and surface defects on the surface to be inspected are automatically determined according to the sharpness of the projected image. Inspections have been performed.

[0003]

As described above, in a configuration in which a coating defect on a surface to be inspected is inspected by irradiating a laser slit light, the width of an area to be inspected in one inspection step is limited. Since it is narrow, there is a problem that it takes a long time to perform a wide range of inspection. Also, when the surface of the vehicle body or the like to be inspected is curved,
With this, the reflected light of the laser slit light also bends, so that the light at the end in the length direction deviates from the light receiving portion of the detecting means, and there has been a problem that inspection of this portion becomes impossible.

For this reason, it is conceivable to irradiate a uniform amount of light from a light irradiating means over a predetermined range of a surface to be inspected and to inspect the presence or absence of a coating defect according to the state of the reflected light. In such a case, there is a problem that a minute defect cannot be detected because halation occurs at a defective portion due to a large increase in the amount of irradiation light. Also,
If the amount of light applied to the surface to be inspected is reduced to perform the minute detection, the amount of reflected light at the bent portion of the surface to be inspected changes significantly. However, there is a problem that it is easy to be erroneously determined to be defective.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and it is possible to accurately inspect the presence or absence of a surface defect without erroneous determination even when the surface to be inspected is curved. It is another object of the present invention to provide a surface state inspection method and apparatus capable of accurately detecting the presence or absence of a minute defect without lengthening the inspection time.

[0006]

The invention according to claim 1 is
A surface state inspection method for inspecting the surface state of an inspected surface by irradiating the inspected surface from a light irradiating unit with light in which at least one of the luminous intensity or the wavelength of the light is gradually changed and detecting reflected light thereof. After dividing the surface to be inspected into a plurality of areas, setting a threshold value as a criterion for judging the surface condition of each area, and comparing the threshold value with an actual detection value By doing so, the presence or absence of a surface defect is determined.

According to a second aspect of the present invention, an average rate of change of reflected light is obtained for each area in accordance with a change in luminance or wavelength of light reflected from a surface to be inspected, and a surface state is determined in accordance with the average rate of change. Is set as a reference value for judging pass / fail.

According to a third aspect of the present invention, the surface to be inspected is irradiated with light of which at least one of the luminous intensity or the wavelength gradually changes from the light irradiating means and the reflected light is detected. A surface state inspection method for inspecting a state, in which a curved state of a surface to be inspected is inspected in advance, and an inspection area is set such that at least one of luminance or wavelength of reflected light changes in a certain direction according to the curved state. Is set, at least one of the change states of the brightness or the wavelength of the reflected light is sequentially detected and compared within the inspection area to determine the presence or absence of a surface defect.

According to a fourth aspect of the present invention, there is provided a light irradiating means for irradiating a surface to be inspected with light of which at least one of a light intensity and a wavelength gradually changes; Detection means for detecting at least one;
Threshold value setting means for dividing the surface to be inspected into a plurality of areas and setting a threshold position serving as a reference for judging whether or not the surface condition is good for each area; and detection performed by the detection means A judgment means for judging the presence or absence of a surface defect by comparing the value with a threshold value set by the threshold value setting means is provided.

According to a fifth aspect of the present invention, there is provided an area setting means for setting an inspection area such that at least one of the luminance and the wavelength of the reflected light changes in a certain direction in accordance with the curved state of the surface to be inspected. is there.

[0011]

According to the first aspect of the present invention, the light irradiated from the light irradiating means to the surface to be inspected and reflected is received by the light receiving means, and at least one of the luminous intensity and the wavelength of the light is changed. It is compared with a threshold set for each predetermined area set in accordance with the bending state or the light irradiation state of the light irradiation unit, and when it is determined that the luminous intensity or wavelength is equal to or larger than the threshold. Means that there is a surface defect.

According to the second aspect of the present invention, the rate of change of at least one of the luminous intensity and the wavelength is measured from the reflected light on the surface to be inspected, and the measured value of the rate of change is set in advance for each area. By comparing with a threshold value corresponding to the average rate of change, the presence or absence of a surface defect is determined.

According to the third aspect of the present invention, at least one of the luminous intensity or the wavelength of the reflected light detected in one inspection area changes in only one direction of increasing or decreasing. An inspection area is set in accordance with the curved state of the surface, and the presence or absence of a surface defect is determined for each inspection area.

According to the fourth aspect of the present invention, the light radiated from the light irradiating means to the surface to be inspected and reflected is received by the light receiving means, and the change of at least one of the luminous intensity or the wavelength is changed for each predetermined area. The presence / absence of a surface defect is determined by comparing the light intensity or the wavelength with the set threshold value or not.

According to the fifth aspect of the invention, at least one of the luminous intensity or the wavelength of the reflected light from each inspection area changes only in one of the increasing direction and the decreasing direction according to the curved state of the inspection surface. The inspection area is set in the inspection area.

[0016]

FIG. 2 shows an embodiment of an inspection apparatus used for carrying out the surface state inspection method according to the present invention.
The inspection apparatus includes a light irradiating unit 1 that irradiates light to a surface W to be inspected such as a vehicle body surface, and a light receiving unit 2 that includes a video camera or the like that receives light reflected on the surface W to be inspected.
A detecting means 3 for detecting the luminance of the reflected light in accordance with an output signal from the light receiving means 2; an area setting means 4 for dividing a surface W to be inspected into a predetermined inspection area; Threshold value setting means 5 for setting a threshold value serving as a reference for judging the quality of the surface condition;
And determination means 6 for determining the presence or absence of a surface defect by comparing the detected value of the above with the above-mentioned threshold value, as described later. The light irradiating means 1 and the light receiving means 2 are
It is supported by the arm of the industrial robot 7 installed at the painting inspection station of the vehicle body, and is configured to trace the surface of the vehicle body according to a preset program ram.

As shown in FIGS. 3 and 4, the light irradiating means 1 includes a support member 9 disposed in a case 8 and a plurality of fluorescent lamps supported by the support member 9 in an inclined state. Light source 10, a first diffusion plate 11 made of an acrylic plate or the like covering the front surface thereof, a honeycomb panel 12 arranged in front of the light source 10, and a second diffusion plate made of an acrylic plate or the like covering the front opening of the case 8. And a plate 13. Then, light emitted from the light source 10 and diffused through the first diffusion plate 11 is supplied to the honeycomb panel 12.
The light that has passed through the opening passage of the honeycomb panel 12 is
The light passes through the diffusion plate 13 and irradiates the inspection surface W.

The honeycomb panel 12 is made of an aluminum plate or the like, and has a large number of open passages 16 defined by horizontal bars 14 extending in the left-right direction and vertical bars 15 extending in the vertical direction in FIG. The light that has passed through the diffusion plate 11 and is introduced into the opening passage 16 in a diffused state is
Further, it is configured to be led out forward while being reflected at a predetermined reflectance by the wall surface of the vertical rail 15. The horizontal rail 14 is set so that the height gradually decreases from the left end to the right end, and the length of the opening passage 16a at the right end is formed to be the shortest. The light introduced into the opening passage 16a at the right end having the short passage length has a small number of reflections on the wall surface of the passage, and a large amount of light is led forward. On the other hand, the light introduced into the opening passage 16b at the left end portion having a long passage length hits the wall surface of the passage and is repeatedly reflected, so that the light is led forward with a reduced amount of light. As a result, the amount of light emitted from the light irradiating means 1 gradually decreases from the right end to the left end as shown by the arrow in FIG.

A black honeycomb panel 17 for preventing diffuse reflection is provided on the wall surface of the case 8 located behind and inside the installation portion of the light source 10. The black honeycomb panel 17 has a matte black coating applied to its wall surface, or a matte black tape is fixed thereto, so that when light introduced into the opening passage hits the wall surface, most of the light is absorbed. Thus, the light emitted from the light source 10 to the side and rear is prevented from being guided to the honeycomb panel plate 12 side.

The threshold value setting means 5 includes the light irradiating means 1
A threshold is set as a reference for judging the presence or absence of a surface defect such as a concave portion or a convex portion formed on the inspected surface W in accordance with the change state of the luminance of the light irradiated and reflected on the inspected surface W from Is what you do. That is, as shown in FIG. 5, when the light radiated from the light irradiating means 1 strikes the inspection surface W and is reflected and received by the light receiving means 2, the reflected light at the right end, where the amount of irradiation is large, is received. Since the reflected light at the left end of the light receiving means 2 is received by the left side of the light receiving means 2 while the light is received by the right side of the means 2, the luminance is represented by a graph as shown in FIG. The brightness at the point A at the left end where the amount of light is small is the smallest value as shown, and the brightness gradually increases toward the right and the point B at the right end.
At the maximum value.

When the surface W to be inspected has a surface defect composed of the convex portion 18, the light reflection direction changes at this portion, and the luminance of the surface W decreases once as shown in a range C of FIG. After that, there will be a partial change that increases rapidly. That is, as shown in FIG. 5, almost no light hits the left side surface 18a of the convex portion 18 located on the side where the amount of irradiation light from the light irradiation means 1 is small. As shown in (2), the brightness of the reflected light decreases. On the other hand, on the right side surface 18b of the convex portion 18, the light at the right end of the light irradiating means 1, that is, the part of the light with the largest amount of irradiation light is reflected and input to the light receiving means 2. As shown by a point C2 in FIG. 6, the detected value of the luminance sharply increases.

Therefore, in the graph shown in FIG. 6, the average rate of change is determined from the average inclination angle of the line indicating the luminance, and a value obtained by adding a fixed correction value to the average rate of change is set as a threshold value. By comparing the value with the actual rate of change in luminance at each inspection point, the presence of the convex portion 18 is detected by detecting a decrease in luminance and a sharp increase in luminance in the range C. . When the surface W to be inspected has a surface defect composed of the concave portion 19, a phenomenon opposite to that of the convex portion 18 occurs, and as shown in a range D of FIG.
Since there is a partial change in which the luminance temporarily increases and then suddenly decreases, the presence of the concave portion 19 is detected by this.

An embodiment of the surface inspection method of the present invention using the apparatus having the above configuration will be described with reference to the flowchart shown in FIG. First, when the control operation is started, after inputting data of the vehicle body to be inspected in step S1, in step S2, the surface W to be inspected is changed according to the shape of the vehicle body based on the data or the light irradiation state of the light irradiation means 1. Partition into a plurality of corresponding inspection areas. Next, in step S3, the luminance of the reflected light from the inspection surface W detected by the light receiving unit 2 and the detecting unit 3 is input according to the irradiation light of the light irradiation unit 1, and in step S4, the luminance of each of the areas is determined. After calculating the average change rate, in step S5, a threshold value α for determining the quality of the surface state corresponding to the average change rate is set and stored.

Next, in step S6, the detected value of the luminance is horizontally scanned rightward from point A at the left end in FIG. 6 for each area. Then, in step S7, it is determined whether or not there is a surface defect at the current scan position by comparing the change rate of the actual luminance at the current scan position with the threshold α of the corresponding area. Step S7 above
In step S8, it is determined whether the surface defect is a concave portion or a convex portion, and the data and the position data are output to a paint repairing unit (not shown) in step S8. Then, in step S9, it is determined whether or not the inspection of all the inspection surfaces W has been completed, and the control in steps S7 to S9 is repeated until it is confirmed that the inspection has been completed.

As described above, the surface to be inspected W
Irradiating a predetermined range of light, and detecting the presence or absence of surface defects by detecting the brightness of the reflected light, the inspection efficiency is greatly improved compared to the inspection method of irradiating laser slit light, A wide range of inspected surfaces W can be inspected in a short time. The light irradiating means 1 irradiates the surface to be inspected W with light whose light quantity gradually changes from one end to the other end thereof, and inspects the presence or absence of a surface defect according to the change state of the luminance of the reflected light. Accordingly, the state of change in luminance is changed depending on whether the surface defect formed on the inspection target surface W is the convex portion 18 or the concave portion 19 as described above. Can be easily and accurately determined.

Further, as described above, the surface W to be inspected is divided into a plurality of inspection areas corresponding to the light irradiation range of the light irradiation means 1 and the shape of the vehicle body. Even when the luminance changes at the bent portion, an accurate inspection can be performed without causing erroneous determination. For example, as shown in FIG.
If the right side of the light source is curved so as to be separated from the light irradiating means 1, the light reflection direction changes according to the curved state, and the light should be originally incident on the right end of the light receiving means 2. Light having a high luminous intensity emitted from the right end of the light irradiation means 1 is reflected toward a position other than the light receiving portion of the light receiving means 2. For this reason, a small amount of light is emitted from the light irradiation unit 1 to the inspection surface W.
8, the change rate of the luminance detected by the detection means 3 reverses from the increasing direction to the decreasing direction at the point E as shown in FIG. 8, and it is erroneously determined that there is a surface defect in this portion. there is a possibility. On the other hand, as described above, the inspection area is divided by the bent portion E based on the vehicle type data and the like input in advance as described above, and the average change rate of the luminance is obtained for each inspection area, and different thresholds are obtained. Value α
Is set, the inspection at the inflection point E is not performed, thereby eliminating the erroneous determination.

Therefore, even when the luminous intensity of the light irradiated from the light irradiating means 1 to the inspection surface W is set to be low as a whole to prevent the halation of the reflected light, the inspection surface W is not affected. It is possible to prevent erroneous determination due to the curvature, and these effects can be obtained at the same time. The inspection area is set sufficiently small in accordance with the curvature of the surface W to be inspected so that the rate of change of the luminance detected by the detection means 3 does not change from the increasing direction to the decreasing direction even in the curved portion. By doing so, the erroneous determination can be eliminated.

In the above embodiment, the threshold value α for detecting a surface defect is set in accordance with the average change rate of luminance obtained for each area. Various modifications are possible without being limited to the examples. For example, as shown in FIG. 6, when the luminance gradually increases from the left end to the right end of the surface W to be inspected, FIG.
As shown in the flowchart of FIG. 7, after inputting the luminance of the light reflected from the inspection surface W in accordance with the irradiation light of the light irradiation unit 1 in step S11, the threshold α is set to 0 in step S12, that is, the state is completely black. Set to the corresponding value. Next, in step S13, the detected value of the luminance is horizontally scanned rightward from point A at the left end of the figure for each area.
Then, in step S14, it is determined whether or not there is a surface defect by checking whether or not the actual luminance at the current scan position is smaller than the threshold value α set in step S12. In this first decision,
Since the detected value of the luminance is always larger than 0, it is determined that there is no surface defect (NO), and the process proceeds to step S15. In this step S15, the value of the scan data is set as a new threshold value α. The threshold α is updated.

Next, in step S16, it is determined whether or not the horizontal scanning of one line has been completed, and the control from step S13 to step S16 is repeated until the determination result is YES. The scan data becomes smaller than the threshold value α at the time when the luminance starts to decrease in the range C or the range D in FIG. 6, so that this is confirmed in step S14, and a surface defect is found at this position. After determining that there is, in step S17, a detection signal of a surface defect is output to the coating repair unit. Thus, even when the threshold value is sequentially updated for each inspection point, it is possible to accurately detect whether there is a surface defect including the concave portion 18 or the convex portion 19 or the like.

In the above-described embodiment, the honeycomb panel 12 having the gradually changing length of the opening passage 16 is provided to gradually change the amount of light emitted from the light irradiating means 1 to the surface W to be inspected. However, instead of the honeycomb panel 12, a filter having a light transmission amount that changes gradually from one end to the other end may be provided. Further, in the above embodiment, the example in which the light irradiating means 1 irradiates the light whose light intensity changes is described. However, the inspecting surface W is irradiated with the light whose wavelength gradually changes from one end to the other end thereof. It may be configured to inspect the presence or absence of a surface defect or the like by measuring the wavelength of the reflected light, or may be configured to irradiate light in which both the luminous intensity and the wavelength gradually change.

[0031]

As described above, according to the present invention, it is possible to easily and accurately detect the presence or absence of a surface defect without increasing the amount of light emitted from the light irradiating means to the surface to be inspected. Even when the inspection surface is curved, erroneous determination that there is a surface defect at the bending point can be effectively prevented. Accordingly, there is an advantage that the inspection surface in a predetermined range can be inspected at a time while preventing the reflected light from causing halation, and even when the inspection surface is wide, it can be inspected at an early stage. is there.

Further, since it is possible to automatically inspect whether the state of the surface defect is a convex portion or a concave portion, by outputting this inspection data to a paint repairing section or the like, the repair work of the surface defect can be performed. There are advantages such as automation.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an embodiment of a surface condition inspection method according to the present invention.

FIG. 2 is a perspective view showing an embodiment of an apparatus for detecting a surface state according to the present invention.

FIG. 3 is a cross-sectional view illustrating a configuration of a light irradiation unit.

FIG. 4 is an exploded perspective view showing a configuration of a main part of the light irradiation unit.

FIG. 5 is an explanatory diagram showing an inspection state of a surface to be inspected.

FIG. 6 is a graph showing a change state of luminance of reflected light.

FIG. 7 is an explanatory diagram showing an inspection state of a curved inspection surface.

FIG. 8 is a graph showing a change state of luminance of the curved surface.

FIG. 9 is a flowchart showing another embodiment of the surface condition inspection method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Light irradiation means 2 Light receiving means 3 Detecting means 4 Area setting means 5 Threshold setting means 6 Judgment means α threshold W Surface to be inspected

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-59-217109 (JP, A) JP-A-1-201108 (JP, A) JP-A-3-99211 (JP, A) JP-A-4- 204314 (JP, A) JP-A-4-301712 (JP, A) JP-A-4-109153 (JP, A) JP-A-4-106461 (JP, A) JP-A-4-109106 (JP, A) JP-A-62-233710 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G01B 11/00-11/30 G01N 21/88

Claims (5)

(57) [Claims] 1. A surface condition for inspecting a surface condition of a surface to be inspected by irradiating a surface to be inspected with light of which at least one of a light intensity and a wavelength gradually changes from a light irradiating means and detecting a reflected light thereof. In the inspection method, a surface to be inspected is divided into a plurality of areas, and a threshold value as a reference for judging the quality of the surface state is set for each area. A surface condition inspection method characterized in that the presence or absence of a surface defect is determined by comparing a detected value. 2. An average rate of change of reflected light is obtained for each area according to at least one of a change state of luminance and a wavelength of light reflected from a surface to be inspected, and a quality of a surface state is determined according to the average change rate. 2. The surface condition inspection method according to claim 1, wherein a threshold value as a reference for determination is set. 3. A surface condition for inspecting the surface condition of the surface to be inspected by irradiating the surface to be inspected with light whose at least one of the luminous intensity and the wavelength gradually changes from the light irradiating means and detecting the reflected light. In the inspection method, the curved state of the surface to be inspected is inspected in advance, and after setting the inspection area so that at least one of the luminance or the wavelength of the reflected light changes in a certain direction according to the curved state, A surface state inspection method, wherein the presence or absence of a surface defect is determined by sequentially detecting and comparing at least one change state of luminance or wavelength of reflected light within a range of an inspection area. 4. A light irradiating means for irradiating a surface to be inspected with light of which at least one of a light intensity and a wavelength gradually changes, and a detecting device for detecting at least one of luminance and wavelength of light reflected from the surface to be inspected. Means for dividing the surface to be inspected into a plurality of areas, threshold value setting means for setting a threshold position serving as a reference for judging the surface condition of each area, and detection by the detection means An apparatus for inspecting a surface condition, comprising: a determination unit for determining the presence or absence of a surface defect by comparing the detected value with a threshold value set by the threshold value setting unit. 5. An area setting means for setting an inspection area such that at least one of luminance and wavelength of reflected light changes in a fixed direction according to a curved state of a surface to be inspected. An apparatus for surface condition inspection as described above.