JPH0312685B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a sensor arrangement structure in a surface defect inspection apparatus for inspecting defects on the surface of an object to be inspected, such as a painted surface of an automobile or a machined object close to a mirror surface.

Prior Art Inspection of defects such as scratches, protrusions, lumps, dirt, etc. on the surface of an object to be inspected as described above can be carried out from visual inspection by inefficient and individual workers to surface inspection using a highly directional laser beam, for example. There is a trend toward automatic inspection using defect inspection equipment.

An example of the inspection principle of a conventional surface defect inspection apparatus using this laser beam will be explained with reference to FIG.

In the figure, a laser slit beam is irradiated from a laser generator 1 onto a surface 2 of an object to be inspected and reflected specularly.
The LS is condensed by a condensing lens 4 in the detection device 3 onto a line sensor 5, which is a photoelectric sensor, for photoelectric conversion.

In this way, since the laser beam has very strong directionality, if there is a defect such as a scratch on the surface 2 of the object to be inspected, the irradiated laser slit beam LS
is scattered there, and the photoelectric conversion output of the line sensor 5 changes, so the presence or absence of defects on the surface 2 can be inspected based on the magnitude of this output.

However, the conventional surface defect inspection apparatus based on such an inspection principle has the following problems.

That is, in order to be able to directly detect the specularly reflected light from the surface 2 of the object to be inspected by the line sensor 5 via the condensing lens 4, it is necessary to align the optical axes with high precision. Therefore, there is usually a very troublesome 3
After aligning the optical axes at the dimensional level, both are fixedly installed, but in this case, the relative positional relationship of the surface 2 of the object to be inspected with respect to the inspection apparatus must also be kept constant.

Therefore, it is only possible to inspect the surface of an object to be inspected that has a flat surface or a constant shape such as the outer circumferential surface of a shaft member, resulting in a problem that the objects to be inspected are limited.

In addition, as a solution to this problem, the relative positional relationship between the laser generator 1, the surface 2 of the object to be inspected, and the detection device 3 can be detected with high accuracy on a three-dimensional level, and based on the detection results, It is conceivable to construct a system with a detection/adjustment mechanism that aligns the optical axes with high accuracy in three dimensions, but such a detection/adjustment mechanism is not only very complicated and large but also expensive. Therefore, it is not practical, and is particularly unsuitable for inspection specifications in which surface defects of an object to be inspected are inspected while relatively moving the inspection device and the object to be inspected.

Furthermore, the conventional apparatus has the problem that the focus of the condenser lens 4 must be adjusted every time the relative positional relationship between the surface 2 of the object to be inspected and the detection device 3 changes.

In view of these various problems, the applicant proposed a method in which the laser slit light that is irradiated onto the surface of the object to be inspected and reflected is once projected and diffused onto a diffusion screen, and the slit-shaped scattered light is inspected using a line sensor. The present invention aims to provide a surface defect inspection device that inspects defects on the surface of an object to be inspected.

According to such a surface defect inspection device, it is possible to perform two-axis optical axis adjustment so that the laser slit light reflected from the object to be inspected is projected even onto a predetermined line-shaped portion on the diffusion screen photographed by the line sensor. This could be the beginning of solving the various problems mentioned above.

However, in the case of such a surface defect inspection apparatus, the problem is how to make the slit image formed by the reflected laser slit light coincide with the line-shaped portion of the diffuser screen.

In other words, the slit image on the diffusion screen is
If the surface of the object to be inspected is flat, a straight line image will not cause much of a problem, but if the outer surface is curved, such as various automobile panels, the slit image will be curved, making alignment difficult. How to deal with this was a serious issue.

Purpose This invention has been made in view of the above background, and provides a sensor arrangement structure in a surface defect inspection device that can easily align a curved slit image to a line-shaped portion on a diffusion screen. The purpose is to

Configuration Therefore, the sensor arrangement structure in the surface defect inspection apparatus of the present invention is such that the slit-shaped scattered light from the diffusion screen is split into two directions by the beam splitter, and the first split light is split into two directions in one of the first spectral directions. A line sensor for defect detection that detects the first slit-like spectrum is arranged, and the second slit-like spectrum is transmitted to the line sensor for defect detection in the other second spectral direction. A plurality of line sensors for detecting posture as spectra for posture detection (in other words, for detecting the posture of the slit image with respect to a line-shaped portion on the diffusion screen) are connected to each line sensor and a second slit-shaped spectrometer. are arranged so that they cross each other.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to FIG. 2 and subsequent drawings.

FIG. 2 is a perspective configuration diagram showing an embodiment of a surface defect inspection apparatus to which the sensor arrangement structure according to the present invention is applied, excluding a control system.

In the figure, 6 is a surface defect inspection device,
It is attached via a mounting plate 7 to the tip of a robot 8 as a mobile mechanical device.

This surface defect inspection device 6 includes a base 9 fixed to a mounting board 7, a second adjustment mechanism 10 attached to the base 9, and brackets 11 and 1 attached to the base 9.
1, a first adjustment mechanism 13 attached to the back side of the movable stay 12 so as to be rotatable in the direction of arrow A, and a movable stay 12 A laser generator 15 is attached to one front end of the movable stay 12 so as to be swingable in the direction of arrow θx via a shaft 14, a detection device 16 is fixedly attached to the other front end of the movable stay 12, It is composed of a defect marker 17 and the like attached near the center of the lower end.

The second adjustment mechanism 10 excluding the control system includes a drive motor 1 having a tachometer generator 18 attached to one end thereof.
9, a spur gear 21 that is rotated by the drive motor 19 via the connecting portion 20, and a spur gear 2 that meshes with the spur gear 21 and rotates the shaft 22 in the direction of arrow _θ1 .
By controlling the rotation of the drive motor 19, the movable stay 12 can be freely moved in the direction of arrow θy with respect to the base 9 via the brackets 11, 11 fixed to the shaft 22. It can make you shake your head. The effect of this swing will be described later.

The first adjustment mechanism 13 excluding the control system includes a drive motor 2 with a tachometer generator 24 attached to one end.
5, a ball screw 26 rotated by the drive motor 25, a bridge section 27 that is fed by the rotation of the ball screw 26, and a bridge section 27 rotatably connected to the shaft section 14 of the laser generator 15. It is composed of a lever 28 that is fixedly connected, a support frame 29 that supports a drive motor 25 to which a tachometer generator 24 is attached, and a ball screw 26 to which a piece 27 is screwed. It is attached to the back side so that it can rotate in the direction of arrow A.

By controlling the rotation of the drive motor 25, the shaft 14 can be rotated in the direction of arrow _θ2 , thereby making it possible to freely swing the laser generator 15 in the direction of arrow θx. Note that this swinging action will also be described later.

The laser generator 15 is, for example, a He-He laser generator, converts the generated laser beam light into laser slit light LS, and converts the generated laser beam light into laser slit light LS.
It is equipped with a lens system that irradiates the painted outer surface 30a of an automobile door 30 as an object to be inspected.

The detection device 16 includes a detection tube 32 having a transmission type diffusion screen 31 such as ground glass fixed to the tip, which projects and diffuses laser slit light LS emitted from the laser generator 15 and specularly reflected from the painted outer surface 30a; A line sensor for defect detection that images a predetermined line-shaped part on the screen 31, and a posture sensor that detects the attitude of a projected image by reflected laser slit light on the line-shaped part on the diffusion screen 31 that is imaged by this line sensor. It is composed of a camera part 33, etc., which has a built-in camera part 33 and a detection tube 32 integrally attached thereto.

The defect marker 17 is a paint material that can be wiped off in the vicinity of the defect that does not interfere with the laser slit light LS when a defect such as a lump or scratch is present at the position of the painted outer surface 30a irradiated with the laser slit light LS and its presence is detected. is sprayed as a mark to indicate the presence of defects.

Next, with reference to FIGS. 3 to 6, which are detailed views of the surface defect inspection apparatus 6 excluding the robot 8 and the defect marker 17, the action of the above-mentioned swing will be explained.

In addition, FIG. 3 is a front view of the surface defect inspection device 6,
4 is a right side view of FIG. 3, FIG. 5 is a front view of the first adjustment mechanism 13, and FIG. 6 is a front view of the second adjustment mechanism 1.
0 is a bottom view of FIG.

First, as shown in FIGS. 3 and 4, the laser generator 15 and the detection device 16 are connected to the optical axis _L1 of the laser generator 15 and the condenser lens of the camera unit 33, which is the optical axis on the detection device 16 side. It is attached to the movable stay 12 so that the optical axis L ₂ of 33a (optical axis of a defect detection line sensor to be described later) intersects within the same plane at an intersection angle δ.

In the first adjustment mechanism 13, when the ball screw 26 is rotated by the drive motor 25 and the bridge part 27 is sent in the direction of arrow B, the movable stay is moved by the shaft 35 via the bracket 34 shown in FIG. 1
A support frame 29 rotatably supported on the shaft 3
5 in the direction of arrow A, and is rotatably connected to the bridge portion 27 by a shaft 36, and the shaft 14 (FIG. 4)
Since the lever 28 fixedly connected to the lever 28 rotates in the direction of arrow C around the shaft 14, the bracket 3 attached to the back side of the movable stay 12 as shown in FIG.
The shaft 14, which is rotatably attached to the shaft 7 via a bearing and has a stationary plate 38 fixed to one end, which fixes the laser generator 15, rotates in the direction of the arrow θ ₂ , and thereby the laser generator 15 shakes his head in the direction of arrow θx, as shown in Figure 3.

Then, when the laser generator 15 turns its head in the direction of the arrow θx, its optical axis L ₁ and the optical axis on the detection device 16 side
The intersection angle δ with L ₂ is adjusted. Note that this first
The drive motor 25 in the adjustment mechanism 13 is rotationally controlled based on the detection result of a posture sensor, which will be described later, and the details will be described later.

Next, in the second adjustment mechanism 10, when the spur gear 21 is rotated by the drive motor 19, the spur gear 21 is rotatably supported on the base 9 via a bearing as shown in FIG. Spur gear 23 meshing with
Since the shaft 22 around which the brackets 11 and 11 are respectively fixed rotates in the direction of the arrow _θ1 , the movable stay 12 to which the brackets 11 and 11 are attached rotates in the direction of the arrow θy as shown in FIG. Shake.

When the movable stay 12 swings in the direction of arrow θy, the laser generator 15 and detection device 16 attached to the movable stay 12 move together with the swing, so that the optical axis The inclination angle ε of the plane formed by L ₁ and L ₂ with respect to the painted outer surface 30a is adjusted. Note that the second adjustment mechanism 10
The drive motor 19 has an inclination angle ε=90°,
That is, the rotation is controlled based on the detection result of the attitude sensor, which will be described later, so that the plane formed by the optical axes L ₁ and L ₂ becomes the normal plane of the painted outer surface 30a, but the details of this will also be described later. .

Next, the internal structure of the detection device 16 according to the present invention will be explained with reference to FIG.

In the figure, a beam splitter 44 provided in the camera section 33 shown in FIGS. From the slit image SL, the slit-shaped scattered light incident through the condenser lens 33a is separated into two directions, a first spectral direction u ₁ and a second spectral direction u ₂ .

Then, the first beam splitter 44
In order to detect the first slit-shaped spectral beam from the beam splitter 44, a sensor arrangement surface 40a facing the spectral direction _u1 is provided with a predetermined beam on the diffusing screen 31 via the beam splitter 44 and the condensing lens 33a. For example, when imaging a line-shaped region 31a,
A line sensor (CCD or MOS type PDA) 41 for detecting defects of 2048 bits (pixels) is arranged horizontally. Note that, as a matter of course, the line sensor 41 and the diffusion screen 31 are located at the focal position of the condenser lens 33a.

In addition, a sensor arrangement surface 40b (sensor arrangement surfaces 40a and 40b are orthogonal to each other) extending in the second spectral direction _u2 by the beam splitter 44 has, for example, two 2048-bit (pixel) attitude sensors.
Line sensor (CCD or MOS) for attitude detection
type PDA) 42, 43, both sensors 42, 43
are parallel to each other, and both sensors 42, 43
and the second slit-shaped beam from the beam splitter 44 are arranged so that they intersect with each other (orthogonally in this embodiment).

Both sensors 42 and 43 detect the second slit-like spectrum from the beam splitter 44 as a posture-detecting spectrum of the first slit-like spectrum with respect to the defect detection line sensor 41, in other words, the line The sensor 41 detects the attitude of the slit image SL with respect to the linear portion 31a on the diffusion screen 31.

Note that _L2 in the figure is the optical axis of the condenser lens 33a and the line sensor 41 for defect detection.

Furthermore, the line sensors 42 and 43 for attitude detection and the diffusion screen are also located at the focal position of the condenser lens 33a.

Furthermore, the relative positional relationship of the line sensors 41 to 43 is such that the reference line R along the arrangement of the light receiving parts of the line sensor 41 intersects the center pixel (1024) of the line sensors 42 and 43.

Furthermore, the interval between the line sensors 42 and 43 is set in accordance with the maximum curvature of the curved surface portion of the painted outer surface 30a of the automobile door 30 that is the object to be inspected (the larger the curvature, the narrower it is).

According to the detection device 16 configured as described above, defect detection and posture detection/adjustment can be performed as follows.

First, for example, as shown in FIG.
If there is a defect P such as a spot or a scratch at the irradiation position on 0a, the laser slit light LS irradiated from the laser generator 15 to the painted outer surface 30a is scattered there and receives specularly reflected light from the painted outer surface 30a. On the diffusion screen 31, there is a defect P as shown in the figure.
A cut slit image SL will be projected at a point corresponding to .

If this slit image SL overlaps and matches the linear portion 31a of the diffusion screen 31 imaged by the line sensor 41 for defect detection shown in FIG. Therefore, defects P on the painted outer surface 30a can be detected.

Moreover, the line sensor 41 for defect detection detects scattered light as shown in FIG.
By receiving the SC, the diffusion screen 31
Since the upper slit image SL is captured, the slit image SL and the line-shaped portion 31a (FIG. 7) may be affected by vibrations of the mechanical system or the first and second adjustment mechanisms 1 described above.
Defects can be detected even if there is some deviation due to poor adjustment of 0 and 13.

Furthermore, since the slit image is enlarged by the diffusion, the detection resolution of the defect P is improved.

Next, for example, in FIG. 10, the painted outer surface 3
When 0a is at the position shown in the actual figure, the slit image SL ₁ on the diffusion screen 31 created by the laser slit light LS ₁ irradiated on the painted outer surface 30a is
Assume that the image is projected onto a line-shaped portion 31a on the diffusion screen 31 shown in FIG.

In this state, when the position of the painted outer surface 30a changes three-dimensionally by rotating the angles α and β to the position shown by the broken line as shown in FIG. From LS ₁
The slit image projected onto the diffusion screen 31 changes three-dimensionally from SL ₁ to LS ₂ .
Changes two-dimensionally to SL ₂ .

Note that between the slit images SL ₁ and SL ₂ , not only a two-dimensional position change but also a change in image length occurs, but this change in length will not be dealt with.

This two-dimensional relative position change of the slit image from SL ₁ to SL ₂ is a position change due to parallel movement in the direction perpendicular to the longitudinal direction of the slit image and rotation of the slit image itself.

The attitude of the slit image SL ₂ whose relative position has changed relative to the above-mentioned line-shaped portion 31a is determined by the line sensors 42 and 43 for attitude detection shown in FIG.
This can be detected by sensing the intersection imaging positions Q ₁ and Q ₂ of the slit image SL ₂ on the slit images SL 2 and 43.

By the way, while the above-mentioned inclination angle ε is kept constant at 90°, the intersection angle δ is adjusted by the above-mentioned first adjustment mechanism 13 from δ ₀ to δ ₁ or δ ₂ as shown in FIG. 12A, for example. If the attitude of the painted outer surface 30a is constant, the slit image SL projected onto the diffusion screen 31 will move as indicated by the arrow G ₁ with the optical axis L ₂ as the center.
direction according to the amount of change in the intersection angle δ.

Further, while the intersection angle δ is kept constant at a predetermined value, the inclination angle ε is adjusted from ε ₀ =90° to ε ₁ as shown in FIG. 12B, for example. When the attitude of the painted outer surface 30a is constant, the slit image SL shown by the dashed-dotted line projected onto the diffusion screen 31 shown by the broken line becomes
On the diffusion screen 31 shown by a solid line, there is an arrow mark relative to the reference line R (see FIG. 7), also shown by a solid line.
G Rotates in _two directions according to the amount of change in the tilt angle ε.

This means that the laser generator 15, the detection device 16,
Even if the relative positional relationship between the outer surface 30a and the painted outer surface 30a changes and the slit image on the diffusion screen 31 is displaced relative to the line-shaped portion 31a imaged by the line sensor 41 for defect detection, the parallelism of the slit image By controlling the amount of rotation of the drive motors 25, 19 of the first and second adjusting mechanisms 13, 10 based on the amount of movement and amount of rotation, and adjusting the crossing angle δ and the angle of inclination ε, a relatively displaced slit image can be obtained. This means that the line sensor 41 for defect detection can return the image to the line-shaped portion 31a on the diffusion screen 31.

The amount of translation and rotation of the relatively displaced slit image with respect to the line-shaped portion 31a is determined by the amount of translation and rotation of the slit image with respect to the line-shaped portion 31a. Based on the positions Q ₁ and Q ₂ , the 11th
As shown in the figure, the value indicating the amount of parallel movement is 1024−
(Q ₁ + Q ₂ )/2 is the value indicating the amount of rotation Q ₁ −
It can be obtained by calculating each Q ₂ .

Therefore, the former value is set as the swing amount of the laser generator 15 in the arrow θx direction corresponding to the required adjustment crossing angle δx, and the latter value is set as the arrow θy of the movable stay 12 corresponding to the required adjustment inclination angle εy. The rotation amount (including the rotation direction) of the drive motor 25 of the first adjustment mechanism 13 is controlled based on the former value, and the second adjustment mechanism is controlled based on the latter value.
By controlling the rotation amount (also including the rotation direction) of the drive motor 19 of the adjustment mechanism 10, the diffusion screen 31 imaged by the line sensor 41 for defect detection can be controlled.
The slit image SL can be positioned in the upper line-shaped portion 31a.

Let us also assume that the coated outer surface 30a is a curved surface as shown in FIG. 13, and the slit image is misaligned with respect to the line-shaped portion 31a.

In such a case, the slit image SL ₃ on the diffusion screen 31 formed by the laser slit light SL ₃ irradiated onto the painted outer surface 30a is curved as shown.

The relationship between the slit image SL ₃ and the line sensors 41 to 43 at this time is, for example, as shown in FIG. _The line sensors 42 _{, 43} set (narrower than the width of [1024−(Q ₁ +Q ₂ )/2,
Q ₁ −Q ₂ ] and the rotation amount of the drive motors 25, 19 based on the calculation results, the 15th
As shown in the figure, a curved slit image SL ₃ can be superimposed on a line-shaped portion 31a on the diffusion screen 31 imaged by the line sensor 41 for defect detection.

Next, an embodiment of the control system of the surface defect inspection apparatus 6 shown in FIG. 2 will be described with reference to FIG. 16.

In the same figure, a first drive detection circuit 45 operates a line sensor (2048 bits) 42 for attitude detection shown in FIG.
While SA is being input, the video signal is sequentially input by driving, and the input video signal is processed frame by frame as follows to create, for example, the slit image SL ₂ or SL shown in FIG. 11 or 14. Address data Q ₁ indicating the cross-imaging position of SL ₃ is sequentially output.

That is, 1 output from the line sensor 42
When a frame worth of video signals is subjected to floating binarization processing, binarized video data as shown in FIG. 17A, for example, is obtained. The fall from "H" to "L" or the center of the rise and fall is detected, and the corresponding address data is output as address data _Q1 indicating the cross-forming position of the slit images.

Similarly, the second drive detection circuit 46 includes a line sensor (2048 bits) 43 for posture detection shown in FIG.
is driven while the measurement command SA is being input to sequentially input the video signal, and the input video signal is subjected to floating binarization processing for each frame. Based on the digitized video data, address data _Q2 indicating the cross-imaging position of the slit images is output.

The third drive detection circuit 47 drives the defect detection line sensor (2048 bits) 41 shown in FIG. 7 while a measurement command SB is input from the control section 53, which will be described later, to sequentially generate video signals. At the same time, the input video signal is processed frame by frame as follows to produce, for example, the painted outer surface 30 shown in FIG.
Numerical data W (W=0 if there is no defect) corresponding to the size of defects such as spots in a is output.

That is, 1 output from the line sensor 41
When a frame worth of video signals is subjected to floating binary processing, if there is a defect P at the irradiation position of the laser slit light on the painted outer surface 30a, for example, the 17th
Binarized video data as shown in Figure C is obtained,
The width from the fall from "H" to "L" of this binarized video data to the subsequent rise from "L" to "H" is detected, and the value indicating the width is calculated as the size of the defect P. Output as numerical data W according to.

The servo amplifier 48 generates an adjustment voltage signal Vx (oscillation) corresponding to the amount of oscillation of the laser generator ₁₅ outputted from a control unit 53, which will be described later _. (can be positive or negative depending on the direction), the tachogenerator 2
1st while receiving speed feedback from 4th.
The drive motor 25 of the adjustment mechanism 13 is rotationally driven.

Similarly, the servo amplifier 49 is connected to a control section 5 which will be described later.
_An adjustment voltage signal Vy ₍ The drive motor 25 of the second adjustment mechanism 10 is driven to rotate while receiving speed feedback from the tachogenerator 18 based on the positive and negative values depending on the swing direction.

The power supply circuit 50 operates while an oscillation command SL is input from a control section 53, which will be described later, so that the laser generator 15 outputs laser slit light.

The driver 51 operates the solenoid valve 5 only when a marker injection command SM is input from the control section 53, which will be described later.
2 to supply air to the spring cylinder 17a of the defect marker 17, thereby spraying the paint from the fine nozzle onto the painted outer surface 30a.

The control unit 53 includes an alignment control unit 54 and a defect inspection control unit 55.
and D/A converters 56, 57, etc.

The alignment control unit 54 is configured by a microcomputer, for example, and receives address data Q ₁ , Q ₂ from the first and second drive detection circuits 45 and 46 and a start command SS from a robot control unit (not shown). , stop command ST, temporary stop command SE, etc. are sequentially processed by the program described later to obtain measurement command SA, oscillation command SL, robot operation command SR, crossing angle adjustment data Dx, tilt angle adjustment data Dy, and defects. Output inspection permission command SOK.

Note that the start command SS is output when the robot 8 shown in _FIG . It is output when the defect inspection end position Fn on the painted outer surface 30a is reached.

Further, the temporary stop command SE is output while the robot 8 is moving between each turning position on the painted outer surface 30a, for example, from position Fm to position Fm+1.

The defect inspection control unit 55 is also configured as a system by, for example, a microcomputer, and receives numerical data W indicating the size of the defect from the third drive detection circuit 47, an inspection start command SSS from a robot control section (not shown), and the like. Inspection stop command
The SST, the defect inspection reference value l from the operation panel (not shown) of the present surface defect inspection device 6, the defect inspection permission command SOK from the alignment control unit 54, etc. are processed by a program to be described later, and the measurement is performed. Command SB and marker injection command SM
Output.

In addition, inspection start command SSS and inspection stop command SST
is output from a robot control unit (not shown) at the same timing as the start command SS and stop command ST, for example.

Hereinafter, the functions of the alignment control unit 54 and the defect inspection control unit 55 will be explained with reference to the program processing flows shown in FIGS. 18 to 20.

Note that, based on the following explanation, the robot 8 in FIG.
It is assumed that the playback operation is performed from the teaching point corresponding to the defect inspection start position F ₀ in FIG.

First, in FIG. 18, which is a processing flow diagram of a program executed by the CPU in the alignment control unit 54, in STEP 1, it is checked whether or not a start command SS has been input from the robot control section. Wait until it is input, and then proceed to STEP 2.

In STEP 2, the measurement command SA is output to the first and second drive detection circuits 45 and 46, and the oscillation command SL is output to the power supply circuit 50.

As a result, the slit laser beam LS from the laser generator 15 is irradiated onto the painted outer surface 30a of the automobile door 30a, and the first and second drive detection circuits 45 and 46 are connected to the posture detection line. Driving of the sensors 42 and 43 is started, and address data Q ₁ and Q ₂ are successively output.

Next, in STEP 3, program SUB shown in FIG. 19 is executed.

In STEP 4 of FIG. 19, the latest address data Q ₁ ,
Import Q ₂ .

In the next STEP 5, based on the address data Q ₁ and Q ₂ taken in in STEP 4, the value 1024-(Q ₁ +Q ₂ )/2 indicating the amount of parallel movement described above is calculated as the intersection angle adjustment data Dx.

In STEP 6, based on the address data Q ₁ and Q ₂ taken in in STEP 4, the value Q ₁ - _{Q 2} indicating the amount of rotation described above is calculated as the tilt angle adjustment data Dy.

Note that the slit image SL projected on the diffusion screen 31 is the line sensor 4 for defect inspection.
Line-shaped part 31a imaged by No. 1 (Fig. 7)
, and when Q ₁ and Q ₂ are Q ₁ and Q ₂ = 1024, both Dx and Dy are zero.

In STEP 7, the intersection angle adjustment data Dx and inclination angle adjustment data Dy calculated in STEP 5 and 6 are simultaneously output to the D/A converters 56 and 57 shown in FIG. 16, respectively.

As a result, the above-mentioned adjustment voltage signals Vx and Vy are outputted from the D/A converters 56 and 57, respectively, and the first and second adjustment mechanisms 13 and 10 are controlled by the action of the servo amplifiers 48 and 49. Drive motor 2
5 and 19 are rotationally driven. By rotationally driving these drive motors 25 and 19, the above-mentioned intersection angle δ and inclination angle ε are adjusted, and the laser slit light LS specularly reflected from the painted outer surface 30a is directed to the diffusion screen 31. The image is formed on a line-shaped portion 31a in .

Then, in STEP 8, address data Q ₁ , Q ₂ again
In the next step 9, check whether Q ₁ , Q ₂ = 1024, and find out that Q ₁ , Q ₂ ≠ 1024
If so, return to STEP 4 and repeat the processing from STEP 4 to 8. If Q ₁ , Q ₂ = 1024, proceed to STEP 10 in Figure 18.
Proceed with the process.

Note that the processing up to this point is performed by robot 8 in Figure 2.
This is the initial positioning that is performed when the robot reaches the defect inspection starting position F ₀ and once stops.

Next, in STEP 10, after the initial alignment is completed, it is possible to start defect inspection, so a robot operation command SR is sent to the robot control section (not shown).
is output and the playback of the robot 8 is started.

In STEP11, the program shown in Figure 19 again
Execute SUB.

In STEP 12, it is checked whether the temporary stop command SE has been input from the robot control unit. If it has not been input, the process proceeds to STEP 13. If it has been input, the process returns to STEP 11 and executes the program SUB shown in Figure 19. repeat.

The reason for carrying out the process like this STEP 12 is that while the robot 8 is moving between each folding position on the painted outer surface 30a, the slit image is
This is to perform only alignment of the SL and not perform defect inspection.

If it is checked in STEP 12 that the temporary stop command SE has not been input, the first
After outputting the defect inspection permission command SOK to the defect inspection control unit 55 shown in Fig. 6, it is checked in STEP 14 whether or not the stop command ST has been input from the robot control unit.
Return to and include the program SUB in Figure 19.
Repeat the processing from STEP 11 to STEP 13, and if they have been input, proceed to STEP 15 and output the measurement command SA and oscillation command SL that were output to the first and second drive detection circuits 45 and 46 and the power supply circuit 50, respectively. Stop and complete all processing.

By performing the above-mentioned processing in the alignment control unit 54, during the playback of the robot 8, the laser generator 15, the detection device 16, and the painted outer surface 3 of the automobile door 30 are
Even if the relative positional relationship between 0a and 0a deviates due to various factors or the painted outer surface 30a is curved, the laser slit light LS regularly reflected from the painted outer surface 30a always detects defects in the diffusion screen 31. An image is formed on the line-shaped portion 31a to be imaged by the line sensor 41, thereby making it possible to inspect the painted outer surface 30a for defects.

The defect inspection is performed as follows.

That is, the defect inspection control unit 5
In FIG. 20, which is a processing flow diagram of the program executed by the CPU in 5, in STEP 16, it is checked whether the inspection start command SSS has been input from the robot control section, and if it has not been input, the robot waits until it is input. , the process advances to STEP 17 when it is input.

In STEP17, the measurement command SB is output to the third drive detection circuit 47.

Then, in the next step 18, a defect inspection permission command is issued from the alignment control unit 54 shown in FIG.
Wait for SOK to be input, and when the command SOK is input, the slit image LS will appear at the line-shaped part 3.
Since it is located at position 1a, the process advances to STEP 19 and the numerical data W is fetched from the third drive detection circuit 47.

Note that this numerical data W is "0" if there is no defect such as a spot or scratch on the irradiation position of the laser slit light LS on the painted outer surface 30a scanned by the playback operation of the robot 8; is a value depending on the size of the defect.

In STEP 20, the numerical data W imported in STEP 19 is compared with the defect inspection standard value l set in advance by operating the operation panel (not shown), and if W≧l, then
The process advances to STEP21, and if W<l, returns to STEP18 and repeats the processes of STEP18 and STEP19.

In STEP 21, since W≧l and the size of the detected defect is larger than the size of the defect to be inspected, a marker injection command SM is output to the driver 51, and the defect marker is thereby 17 of the spring cylinders 17 are activated, paint is sprayed near the defect on the painted outer surface 30a detected from the defect marker 17, and the position of the defect is marked.

Then, in STEP 22, it is checked whether the inspection stop command SST has been input from the robot control unit, and if it has not been input, the process returns to STEP 18.
The processing from STEP 18 to STEP 21 is repeated, and if the input has been received, the processing proceeds to STEP 23, where the counting command SB that has been output to the third drive detection circuit 47 is stopped, and all processing is completed.

By performing the above processing in the defect inspection control unit 55, it is possible to perform defect inspection over the entire area of the painted outer surface 30a of the automobile door 30 shown in FIG.

According to the embodiment described above, in addition to the effects described in the explanation of FIG. 7, the following effects are achieved.

In other words, since the two-dimensional plane on the diffusion screen 31 is used as a reference to detect positional deviations and align the positions, not only is there no need for troublesome focus adjustment, but also a positional deviation detection system (orientation sensor) is required.
and alignment adjustment system (first and second adjustment mechanisms)
The configuration and control contents are relatively simple, and since the same light source and the same optical system (condensing lens) are used for defect detection and positional deviation detection, miniaturization can be achieved.

Moreover, since it can be configured without using any special mechanism or sensor, it is inexpensive and practical.

Furthermore, the two-axis detection/adjustment system can widen the positional tolerance between the inspection device and the object to be inspected, making it possible to easily perform the above-mentioned mobile inspection mode without compromising detection stability. This makes it possible to inspect various objects for defects.

Furthermore, by utilizing the action of the beam splitter 44, the line sensor 41 for defect detection, the line sensors 42, 43, etc. for posture detection are provided on different sensor placement surfaces 40a, 40b, and the line sensors 42, 43 Since the interval can be freely set, even a curved slit image can be made to match the line-shaped portion 31a of the diffusion screen 31.

In the above embodiment, the vehicle door 30 is fixed and the surface defect inspection device 6 is transferred by the robot 8, but conversely, the surface defect inspection device 6 is fixed and transferred to the vehicle. Surface inspection can also be performed by moving the door 30.

Further, in the above embodiment, a painted automobile door was used as an example, but it is also possible to inspect various other objects as long as they are close to a painted vehicle body or a mirror surface.

Furthermore, in the above embodiment, the intersecting angle δ of the optical axes L ₁ and L ₂ is adjusted by moving the laser generator 15, but the detection device 16 is moved. Moreover, the first and second adjustment mechanisms 13 and 10 are not limited to the embodiments, and may have any structure as long as the intersection angle δ and the inclination angle ε can be adjusted.

Furthermore, although the above embodiment has been described using a transmission type diffusion screen 31, it goes without saying that a reflection type diffusion screen can also be used.

In the above embodiment, the part rotated by the shaft 14 is made only of the lens system that converts the laser beam into laser slit light, and the laser beam is guided to the lens system using an optical fiber. For example, the structure of the surface defect inspection device attached to the robot 8 can be made more compact.

Effects As described above, according to the present invention, the slit-shaped scattered light from the diffusion screen is split into two directions by the beam splitter, and the first slit is split in one of the first spectral directions. A line sensor for defect detection that detects a slit-like spectrum is arranged, and the second slit-like spectrum is arranged in the other second spectral direction for detecting the attitude of the first slit-like spectrum with respect to the line sensor for defect detection. Since a plurality of attitude detection line sensors are arranged so that the line sensors and the second slit-shaped spectral lines intersect with each other, the line sensors for detecting defects can be detected even when the slit image is curved. It becomes possible to easily align the line-shaped portion on the diffusion screen to be imaged.

Accordingly, by using the surface defect inspection apparatus to which the present invention is applied, surface defect inspection can be performed on objects to be inspected whose outer surfaces are curved, such as various types of automobile panels.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of the inspection principle of a conventional surface defect detection device, and FIG. 2 is an example of a portion of a surface defect inspection device to which the sensor arrangement structure according to the present invention is applied, excluding the control system. A perspective configuration diagram showing
FIG. 3 is a front view showing details of the surface defect detection device 6 of FIG. 2 excluding the defect marker 17;
The figure is a right side view of FIG. 3, FIG. 5 is a detailed view of the first adjustment mechanism 13, and FIG. 6 is a detailed view of the second adjustment mechanism 1.
0, FIG. 7 is a perspective view showing the internal structure of the detection device 16 according to the present invention, and FIGS. 8 and 9 are
10 is a two-dimensional diagram of a slit image on the diffusion screen 31 based on a tertiary relative position change of the painted outer surface 30a. FIG. 11 is an explanatory diagram showing how the slit image is detected by the line sensors 42 and 43 for attitude detection shown in FIG. 7, and FIG. FIG. 13 is a schematic diagram showing how the position of the slit image changes when ε is changed. FIG.
An explanatory diagram showing how the slit image shown in FIG. 13 is detected by the line sensors 42 and 43 for attitude detection shown in FIG. 7, and FIG. 15 shows the slit image shown in FIG. FIG. 16 is a block diagram showing an embodiment of the control system of the surface defect inspection device 6 shown in FIG. 2, and FIG. The waveform diagrams in FIGS. 18 to 20 used to explain the functions of the drive detection circuits 45 to 47 are the programs executed by the CPUs in the alignment control unit 54 and defect detection control unit 55 in FIG. 16, respectively. It is a process flow diagram. 6... Surface defect inspection device, 8... Robot, 9
... Base, 10 ... Second adjustment mechanism, 12 ... Movable stay, 13 ... First adjustment mechanism, 15 ... Laser generator, 16 ... Detection device, 17 ... Defect marker, 19, 25 ... Drive motor, 30 ... Automobile door (object to be inspected), 30a ... Painted outer surface,
31... Diffusion screen, 33... Camera section, 3
3a...Condenser lens, 41...Line sensor for defect detection, 42, 43...Line sensor for posture detection, 44...Beam splitter, 45...First
drive detection circuit, 46... second drive detection circuit,
47... Third drive detection circuit, 48, 49... Servo amplifier, 50... Power supply circuit, 51... Driver, 52... Solenoid valve, 53... Control unit, 54...
Control unit for alignment, 55... Control unit for defect detection.

Claims (1)

[Claims] 1. Laser slit light irradiated onto the surface of the object to be inspected and reflected is projected onto a diffusion screen and diffused,
In a surface defect inspection device that inspects defects on the surface of the object to be inspected by detecting the slit-shaped scattered light, the slit-shaped scattered light from the diffusion screen is detected by a beam splitter. Split into two directions,
A defect detection line sensor for detecting the first slit-like spectrum is arranged in one first spectral direction, and a line sensor for detecting the defect is arranged in the other second spectral direction to detect the second slit-like spectrum. A plurality of attitude detection line sensors are arranged to detect the first slit-shaped spectral spectrum as an attitude detection spectral spectrum with respect to the line sensor, and each of the line sensors and the second slit-shaped spectral spectrum intersect with each other. A sensor arrangement structure in a surface defect inspection device characterized by: