JP2002328094A - Led ring lighting and image inspecting device with it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection image which is picked up with a definite shade for radial flaw/wrinkle inspection, fold-line inspection, and rough inspection on a plane, as well as vertical flaw inspection on a side surface and vertical rough inspection of a tall work. SOLUTION: An LED ring lighting 1 comprises multiple LEDs 3 arrayed concentrically and projects an inspection beam to a work at image inspection. All the LEDs 3 on the same circle are fitted aslope to a main body vessel 2 so that they are tangentially tilted by almost the same fitting angle θ. If the extension direction of rough such as flaw, chap, fold-line, etc., present on the surface of work facing the LED ring lighting 1 is radial, or if the extension direction of rough present on the peripheral surface of he work equals to height direction, the optical axis direction of inspection beam crosses the extension direction to present a definite shade at the rough.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to scratches or crevices on a side surface of a cylindrical object such as a cap or a mouth of a bottle or plastic bottle, or scratches or folds extending radially on a work on a disk. The present invention relates to an LED illumination used for image inspection of a crack or the like by image processing, and an image inspection device using the same.

[0002]

2. Description of the Related Art Heretofore, in image inspection of a cylindrical or disk-shaped work, for example, a ring-shaped illumination has been generally used for capturing an inspection image. Ring-type illumination includes a ring fluorescent lamp and an LED ring illumination.

FIG. 13 shows a conventional LED ring light 101.
The outline of is shown. As shown in FIG. 1A, the LED ring illumination 101 is a thin cylindrical donut-shaped main body container 1.
In this example, a large number of LEDs 103 are arranged in concentric circles in a circle 02. Further, each LED 103 is the same as FIG. (A) as viewed in the direction indicated by the arrow A, FIG. (B), and FIG.
As shown in (2), they are arranged at an angle in the direction of the center O of the circle, so that inspection light can be applied to the upper surface and the peripheral surface of a cylindrical or disk-shaped work.

[0004]

However, the above L
In the ED ring illumination 101, since the irradiation direction of the inspection light is directed to the center of the ring, that is, the optical axis of each LED 103 of the LED ring illumination is inclined inside the ring and in the direction of the ring center O. For this reason, it is useful for concentric scratch inspection of disk-shaped work, but not suitable for radial scratch inspection. No cracks in the longitudinal direction could be clearly detected in the crack inspection.

[0005] This is because, in a captured inspection image,
Scratches and irregularities are detected as shaded parts of the light illuminated obliquely (blackish contours) or just specularly reflected parts (appearing white). This is because the number of reflection portions is reduced, and it cannot be detected as a flaw.

That is, as shown in FIG. 14, for example, when inspecting a concentric flaw A1 on the surface (upper surface) W1a of a disc-shaped work W1, light is irradiated from a direction perpendicular to the flaw direction. , And shadows are easy to detect, but in the case of a radial wound A2, irradiation is performed in the same direction as the wound,
The wound will be illuminated in a manner similar to illumination from directly above, thus making shadowing less likely.

[0007] As shown in FIG. 15, the same applies to the side surface W2b of the cylindrical work W2.
When the LED ring light 101 is placed on the upper side of FIG.
As shown in FIG. 6, when the work W is viewed from above, the inspection light is light in a direction from the outer peripheral side toward the center of the work W.
For this reason, although the shadow A3 in the horizontal direction is apt to produce shadows, the wound A4 in the vertical direction (or unevenness in the vertical direction) is in principle equivalent to the case where the laser beam is irradiated from directly above the scratch D, and no shadow is generated. .

Therefore, the conventional LED ring illumination has a problem that an appropriate result cannot be obtained in image processing.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of a flat radial scratch / wrinkle inspection, a fold inspection, an unevenness inspection, or a vertical flaw inspection and a vertical inspection of a side surface of a work having a height. It is an object of the present invention to provide an LED ring illumination capable of clearly adding a shadow to an inspection image to be taken at the time of inspection for unevenness in a direction, and an image inspection apparatus having the same.

[0010]

In order to solve the above-mentioned problems, in the LED ring illumination according to the present invention, a large number of LEDs are arranged concentrically around an opening provided in the center. In the LED ring illumination that irradiates the work with inspection light during image inspection using image processing technology, all the LEDs on the same circle are inclined so that their optical axes have substantially the same mounting angle in the tangential direction of the circle. It was attached.

[0011] In such a configuration, the extending direction of the unevenness such as a scratch, a crack, or a fold existing on the surface of the work facing the LED ring illumination is in the radial direction. When the extending direction is the height direction, the optical axis direction of the inspection light emitted from each of the multiple LEDs is a direction intersecting the extending direction. Therefore, a noticeable shadow can be added to the unevenness.

According to the LED ring illumination of the present invention, a large number of LEDs are arranged concentrically around an opening provided in the center, and the LED ring illumination is applied to a workpiece when performing image inspection using image processing technology. In the LED ring illumination that irradiates the inspection light, all the LEDs on the same circle are mounted so that their optical axes are inclined so as to have substantially the same mounting angle in the tangential direction of the circle, and the LEDs of the circles adjacent to each other are mounted. Both LEs
It is assumed that the inclination direction of the tangential direction in D is opposite.

[0013] In such a configuration, the extending direction of the irregularities such as scratches, crevices, and folds existing on the surface of the work facing the LED ring illumination is in the radial direction. When the extending direction is the height direction, the optical axis direction of the inspection light emitted from each of the multiple LEDs is a direction intersecting the extending direction. Therefore, a noticeable shadow can be added to the unevenness. In addition, symmetrical shadows can be provided on both sides of the irregularities.

In the LED ring illumination according to the third aspect, a large number of LEDs are arranged concentrically around an opening provided at the center, and the LED ring illumination is applied to a workpiece when performing image inspection using image processing technology. In the LED ring illumination for irradiating the inspection light, all the LEDs on the same circle were inclined and mounted such that their optical axes alternately turned in the tangential direction of the circle and had substantially the same mounting angle. It was taken.

[0015] In such a configuration as well, when the extending direction of the irregularities such as scratches, crevices, and folds present on the surface of the work facing the LED ring illumination is in the radial direction, or when the irregularities existing on the peripheral surface of the work are present. When the extending direction is the height direction, the optical axis direction of the inspection light emitted from each of the multiple LEDs is a direction intersecting the extending direction. Therefore, a noticeable shadow can be added to the unevenness. In addition, symmetrical shadows can be provided on both sides of the irregularities.

In the LED ring illumination of the fourth aspect, the work is a rotating body, and the axis of rotation passes through the center of the circle.
In the ring illumination, when the distance from the inspection site on the side surface of the work to the LED surface is E, the radius at the inspection site is r, and the radial distance from the center of the circle to each LED is p, the mounting angle is ^{tanθ = r (p 2 -r 2} )
^The angle was set to ^1/2 / Ep. In the present invention, the shape of the rotating body is not limited to the rotating body in a strict sense, and includes other shapes having the rotating body as a basic shape.

According to a fifth aspect of the present invention, there is provided an image inspection apparatus, wherein the LED ring illumination according to any one of the first to fourth aspects and a camera for imaging a workpiece through an opening of the LED ring illumination. And image processing means for processing an inspection image captured by the camera and performing a predetermined inspection on the surface of the work.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings.

(First Embodiment) FIG. 1 is a view showing an LED ring illumination 1 according to the present invention. The LED ring illumination 1 has a large number of LEDs 3 arranged concentrically in a thin cylindrical donut-shaped main body container 2 having an opening 2a in the center, as in the prior art. The mounting position of each LED when the LED ring illumination 1 is viewed from above or below is the same as in the conventional example. In FIG. 1, the LEs are drawn on two concentric circles.
Although the arrangement of D3 is shown, the number of circles may be increased or decreased as necessary.

Each LED 3 has in its radial cross section:
When the LED ring illumination 1 is viewed from the side, it is installed so that the optical axis faces slightly inward as shown in FIG. Hereinafter, this angle is referred to as a mounting angle φ in the radial direction (in the case of 0 °, it faces directly below).

Each LED 3 has an LE on a certain concentric circle.
When D3 is viewed in a cross section in the tangential direction, it is installed obliquely with a constant inclination as shown in FIG. Hereinafter, this angle is referred to as a tangential mounting angle (the mounting angle of the present invention) θ (directly downward when 0 °).

That is, in the conventional example, the radial mounting angle φ ≧ 0 and the tangential mounting angle θ = 0 °, but in the present embodiment, the tangential mounting angle θ> 0 °. .

The LED ring illumination 1 having the above-described structure is used for performing various inspections on the upper surface (front surface) W1a of a flat work W1 as shown in FIG. The center position O of the work W1 is aligned with the center of the work W1. In this case, the inspection image of the flat work W1 is the LED ring illumination 1
Is imaged by the camera through the central opening 2a of the camera. Inspection items include, for example, inspection for the presence or absence of radial scratches and cracks on the upper surface W1a of the work W1, and whether a fold is provided at a correct position if provided.

When the inspection W is performed by the LED ring illumination 1, when the inspection light is radiated by the LED ring illumination 1, if the upper surface W1a of the work W1 has irregularities A2 such as a flaw or a crack extending radially during the inspection, the direction P of the light is changed to the upper surface W1a. , But in a direction orthogonal to the radiation on the upper surface W1a. That is, the light from each LED 3 is emitted from a direction orthogonal to the radial unevenness A2 to be detected. Therefore, an image is easily obtained in which shadows are easily formed and inspection and detection can be easily performed. In the case of such an application example, the attachment angle φ in the radial direction may be negative near 0 (outward).
The mounting angle θ in the tangential direction is suitably about 15 ° to 80 °.
The larger the tangential mounting angle θ, the more distinct the shadow becomes. Therefore, by using the LED ring illumination 1, it is possible to improve the inspection results when performing a flat radial flaw / wrinkle inspection, a fold inspection, or an unevenness inspection.

FIG. 3 is a diagram showing an example of application to inspection of a side surface W2b of a work W2 having a cylindrical surface. The work W2 is, for example, a cap of a plastic bottle, a cap of a bottle, or the like, and its purpose is to detect vertical irregularities (position marks, scratches, tears, etc.). Also in this case, the LED ring illumination 1 is arranged above the work W2. In addition, the inspection image of the side surface W2b of the work W2 is obtained by capturing the work side surface with a camera from the front (outer circumferential direction) of the work W2 or from above through a lens or a mirror (a specific example will be described later).

In such a case, when the side surface W2b of the work W2 has unevenness A4 extending in the vertical direction (height direction), when the inspection light is irradiated by the LED ring illumination 1,
The direction P of the light beam does not point in the vertical direction with respect to the side surface W2b, but points in the direction intersecting with the vertical direction of the side surface W2b (direction having orthogonal components) (see FIG. 4). That is, the light from each LED 3 is emitted from a direction intersecting the radial unevenness A4 to be detected. Therefore, an image is easily obtained in which shadows are easily formed and inspection and detection can be easily performed. Therefore, by using the LED ring illumination 1, it is possible to improve the result of the inspection when performing the vertical flaw inspection and the vertical unevenness inspection of the side surface W2b of the work W2 having the cylindrical surface.

In the case of this example, LE is calculated from the work diameter.
Since the diameter of the D-ring illumination 1 must be larger, the mounting angle φ in the radial direction is made positive. If the tangential mounting angle θ is appropriately set to about 15 ° to 80 °, the irradiation direction is angled by the tangential mounting angle θ for the vertical scratches to be detected. Can be attached.

On the other hand, in the LED ring illumination 1, the tangential mounting angle θ of the LED 3 is as follows.
Can be determined.

That is, as shown in FIG. 5, the diameter of the work W2 is D, the vertical distance to the uneven portion Q to be detected is E, LE
Assuming that the diameter (of a certain concentric circle) of the D array is C: r = D / 2 p = C / 2: sinψ = r / p tanθ = rcosψ / E = r (p ² −r ² ) Θ and φ may be determined from the relational expression of ^1/2 / Ep · tan φ = (p−rsinψ) / E = (p ² −r ² ) / Ep.

For example, D = 30 mm, C = 70 mm, E
In the case of = 30 mm, it is optimal that θ = 24 ° and φ = 44 °. In this case, light is irradiated from the direction of 24 ° to the vertical unevenness. To irradiate light at a deeper angle, C may be increased.

The work W2 having a cylindrical surface has been mainly described.
The same effect can be obtained even in the case of another shape having the rotating body as the basic shape.

(Second Embodiment) FIG. 6 is a view corresponding to FIG. 1 and shows another LED ring illumination 11 according to a second embodiment of the present invention. Hereinafter, only the configuration different from that of the first embodiment will be described, and the same portions will be denoted by the same reference numerals and description thereof will be omitted.

That is, in the LED ring illumination 11 of the present embodiment, as shown in FIG. 3D, which is a view taken in the direction of arrow C in FIG. The light beam directions of all the arranged LEDs 13 (hereinafter, referred to as second LEDs) have the opposite inclination to the LEDs 3 (hereinafter, referred to as first LEDs) arranged along the outer circle, that is, the tangential mounting described above. The angle θ2 of the second LED 13 which is an angle
And the relationship between the angle θ1 of the first LED 3 and θ2 ≒ −θ1
It is what it was. The mounting angle φ in the radial direction described above
About the same.

The LED ring illumination 11 having such a configuration
According to this, for example, radial unevenness existing on the upper surface (front surface) W1a of the flat work W1 described in FIG. 2 and unevenness vertically existing on the cylindrical work side surface W2a illustrated in FIG. 3 and FIG. A4 can irradiate the work W2 with light rays having both directions of one side and the other side in the tangential direction. Therefore, it is possible to provide a bilaterally symmetric shadow on the unevenness A4 and the like. The same applies to a partial projection having no length, for example, a hemispherical projection.

Therefore, when inspecting for the presence or absence of a flaw based on the strength or length of the edge of a marker or the like, the purpose is to measure the position of the irregularities A4 (markers indicating wrinkles, folds, position references, etc.). In this case, in the image processing for the inspection image, the center point in the left-right direction can be detected with high accuracy based on the change in shading of the concavo-convex A4 portion. As a result, it is possible to inspect the regularity of irregularities and the accuracy of the position with high inspection accuracy based on the position of the edge portion.

FIG. 6 shows an arrangement in which the first and second LEDs 3 and 13 are arranged on two concentric circles, respectively. The mounting angles in the tangential direction between them may be set alternately to θ1 and θ2. Although the effects of the present embodiment described above are not particularly shown, for the LEDs arranged on the same circumference, the mounting angle in the tangential direction is θ.
It goes without saying that the same can be obtained by alternately setting 1 and θ2.

(Third Embodiment) FIG.
It is a figure showing the example of image inspection device 51 using ED ring lighting 1 (11). This figure shows the inspection of the upper surface Wa and the peripheral surface Wb of the cap W of the container 100 such as a PET bottle or a bottle, or the presence or absence of a crack A on the surface of the flat work, the crack or scratch on the upper surface, or the detection of an uneven position mark. Is used for the image inspection. Although the image inspection apparatus 51 can use either of the above-described LED ring illuminations 1 and 11, it is assumed that the image inspection apparatus 51 includes the LED ring illumination 11 of the second embodiment for convenience.

In the example shown in FIG.
A camera 52 installed above the container 100 as if capturing an image of the upper surface Wa of the cap, and a cap W
Lens 53 provided between the camera and the camera 52, an LED ring illumination 11 provided outside the convex lens 53, and an image processing device (image processing means) 54 to which an inspection image captured by the camera 52 is input. ing.

The convex lens 53 refracts the light from the cap peripheral surface Wb at the peripheral portion, enlarges the image (like a magnifying glass), and forms an image on the lens of the camera 52. Upper surface Wa of cap W and peripheral surface W
b can be imaged at the same time. The diameter of the convex lens 53 and the distance to the cap W are set as follows.

That is, as shown in FIG. 8, the diameter of the cap W is D, the lower position of the peripheral surface Wb to be observed and the upper surface W
E is the distance (a height of the cap W) from a, and the top surface W of the cap is
When the distance from a to the convex lens 53 is G, the diameter of the convex lens 53 is C, and the focal length is F, setting is made such that F> (G + E) and C> FDD / (FGE). Have been.

The smaller the F, the smaller the magnification of the upper surface Wa.
The enlarging rate of the peripheral surface Wb increases, and the smaller the G, the higher the upper surface W
a is small, and the magnification of the peripheral surface Wb is large.
For example, if D = 30 (mm), E = 30, and G = 30, when F = 100 mm, C needs to be 75 mm or more. When D = 5 (mm), E = 30, and G = 10 mm, and the peripheral surface is focused on, if C is 80 mm, F needs to be 45 mm or more. In the present embodiment, F and C are approximately the same size and approximately three times D.

When the angle at which the peripheral surface Wb is viewed is α, tan α = C / F, when α = 15 °, C / F> 0.27, when α = 30 °, C When α = 45 °, C / F> 1, and when α = 30 °, C / F> 1.73. C / F> 0. 27.

Thus, as shown in FIG. 9A and FIG. 10, for example, as shown in FIG. 9A and FIG. 10, images of the upper part, the central part, and the lower part of the cap peripheral surface Wb are outside the image of the cap upper surface Wa. Further, inspection images G1 and G2 in which an image of the upper portion of the container 100 is projected further outward and an outer peripheral portion 53a of the convex lens 53 is projected on the outermost periphery can be captured.

In the image processing device 54, for example, when a flaw inspection is performed on the upper surface Wa and the peripheral surface Wb of the cap W, when the inspection image G1 is input, the image processing device 54 shown in FIG.
As shown in (a), the center O of the circle 200 is obtained by detecting the innermost circle 200 in the input inspection image G1. The innermost circle 200 is a boundary between the upper surface Wa of the cap W and the peripheral surface Wb. Next, the donut-shaped image is converted into a rectangular image as shown in FIG. 9B by polar coordinate development centered on the center O of the circle. Here, the horizontal axis x of the converted image corresponds to the angle, and the vertical axis y corresponds to the distance from the center O of the circle.

Thereafter, by detecting the edge (A4) extending in the vertical direction from the rectangular image, the presence or absence of a scratch or mark extending in the vertical direction on the peripheral surface of the cylinder is inspected. Note that FIG.
Inspection image G2 shows an example in which a groove B extending in the height direction exists on the peripheral surface Wb of the cap W,
When detecting such a groove B, inspections such as the presence or absence, the number, and the groove width of the groove B are performed by the same processing as described above.

Therefore, in the above-described image inspection apparatus 51, by providing the above-described LED ring illumination 11, the above-described inspection of the cap W and the like can be performed, and the inspection can be accurately performed.

According to the image processing apparatus 54 of the present embodiment, the first embodiment has been described with reference to FIG. 2 based on the inspection image G1 shown in FIG. Radial tear A on the surface W1a of a flat work
Inspection for cracks and scratches can also be performed. Also,
When the image processing device 54 performs only the inspection on the surface W1a of the flat work, the lens 53 is unnecessary. Therefore, the lens 53 may be removed from the configuration shown in FIG. Even in that case, the above-mentioned LE
By providing the D-ring illuminations 1 and 11, it is possible to accurately inspect the surface of the flat work for the presence or absence of radial tearing, cracking, and flaws based on the captured inspection image.

(Other Image Inspection Apparatus) The above-mentioned LE
The image inspection apparatus using the D-ring illuminations 1 and 11 may have, for example, the configuration shown in FIGS. 11 and 12 in addition to the above. That is, the image inspection device 61 of FIG.
Has a camera 52 disposed above the cap W in the same manner as that shown in FIG. 7. By installing a concave mirror 62 between the camera 52 and the cap W, This is to capture an inspection image in which the peripheral surface Wb is projected on the outer periphery of the upper surface Wa of the cap W. However, unlike the one shown in FIG. 7, the upper surface Wa and the peripheral surface Wb shown in the captured inspection image are discontinuous. In this case, as shown, the LED ring illuminations 1 and 11 need to be arranged at positions where the reflection of the image by the mirror 62 is not hindered. Other configurations are the same as those shown in FIG.

The image inspection apparatus 71 shown in FIG. 12 includes one camera 52 arranged above the cap W and three or more cameras 52 arranged around the cap W. Is used to capture a plurality of inspection images. In this case, it is sufficient that the LED ring illuminations 1 and 11 are arranged at positions where the imaging of the inspection image by each camera 52 is not hindered. Other configurations are the same as those shown in FIG.

[0050]

As described above, claims 1 to 4 are described.
In the LED ring illumination of the above, when the extending direction of the unevenness existing on the surface of the work is the radiation direction or the extending direction of the unevenness existing on the peripheral surface of the work is the height direction, the optical axis of the inspection light By making the direction intersect with the direction in which they extend, a noticeable shadow can be added to the irregularities. Therefore, by using the LED ring illumination of the present invention, when performing a flat radial scratch / wrinkle inspection, a fold inspection or unevenness inspection, or a vertical scratch inspection or a vertical unevenness inspection on a side surface of a work having a height. It is possible to improve the results of the test.

Further, in the LED ring illumination of the second to fourth aspects, symmetrical shadows can be formed on both sides of the above-mentioned irregularities. Therefore, it is possible to improve the accuracy in calculating the position of the unevenness during the image inspection. In addition, the same effect can be obtained particularly for irregularities having no length.

Further, in the image inspection apparatus according to the fifth aspect, by providing the above-mentioned LED ring illumination, it is possible to inspect a flat radial scratch / wrinkle, a fold inspection, an unevenness inspection, or a side surface of a work having a height. Inspection accuracy when performing a vertical flaw inspection and a vertical unevenness inspection is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention,
(A) is a plan view of the LED ring illumination, (b) is a view as viewed from the arrow (a), and (c) is a view as viewed from the arrow (a).

FIG. 2 is a schematic diagram showing a direction of inspection light with respect to a work upper surface in the embodiment.

FIG. 3 is a schematic diagram showing a direction of inspection light on a side surface of a work in the embodiment.

FIG. 4 is a schematic diagram showing a direction of inspection light on a side surface of the work when the work is viewed from above in the embodiment.

FIG. 5 is a diagram illustrating a mounting angle of a tangential direction of an LED in the LED ring illumination.

FIGS. 6A and 6B are views corresponding to FIG. 1 in a second embodiment of the present invention, wherein FIG. 6A is a plan view, FIG. FIG. 2B is a view as viewed in the direction of the arrow B, and FIG.

FIG. 7 is a schematic diagram of an image inspection apparatus according to a third embodiment of the present invention.

FIG. 8 is a diagram showing specifications of an optical system according to the embodiment.

FIG. 9 is a diagram illustrating an example of an inspection image and image processing using the inspection image.

FIG. 10 is a diagram showing another inspection image.

FIG. 11 is a schematic view showing another image inspection apparatus of the present invention.

FIG. 12 is a schematic diagram showing another image inspection apparatus of the present invention.

FIG. 13 is a view showing a conventional LED ring illumination,
(A) is a plan view, (b) is a view as viewed from an arrow (a), and (c) is a view as viewed from an arrow (b).

FIG. 14 is a schematic diagram showing the direction of inspection light on the upper surface of a work.

FIG. 15 is a schematic diagram showing directions of inspection light on a side surface of a work.

FIG. 16 is a schematic diagram showing directions of inspection light on a side surface of the work when the work is viewed from above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 LED ring illumination 2 Main body container 2a Opening part 3 (1st) LED 11 LED ring illumination 13 (2nd) LED 51 Image inspection device 52 Camera 53 Convex lens 54 Image processing device 61 Image inspection device 62 Mirror 71 Image inspection device A2 Irregularities extending radially on the upper surface of the work A4 Irregularities extending in the vertical direction on the side of the work O Circle center of LED ring illumination θ1 Mounting angle in the tangential direction of the first LED (mounting angle) θ2 Tangent line of the second LED Direction mounting angle (mounting angle)

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Chinori Norimune 2-27-4-605 Shimonagaya, Konan-ku, Yokohama-shi, Kanagawa F-term (reference) 2F065 AA03 AA49 BB06 BB08 DD04 FF04 GG07 HH12 JJ03 JJ19 JJ26 2G051 AA12 AA71 AB07 BA02 BB02 BB11 CA04 CB01

Claims (5)

[Claims] 1. An LED in which a large number of LEDs are arranged concentrically around an opening provided in the center, and which irradiates inspection light onto a workpiece when performing image inspection using an image processing technique.
An LED ring lighting device comprising: a D-ring lighting device, wherein all the LEDs on the same circle are mounted to be inclined so as to have substantially the same mounting angle in the tangential direction of the circle. 2. A plurality of LEDs are arranged concentrically around an opening provided at the center, and an LE for irradiating inspection light to a workpiece at the time of image inspection using image processing technology.
In the D-ring illumination, all the LEDs on the same circle are tilted and mounted so that their optical axes have substantially the same mounting angle in the tangential direction of the circle, and the tangents of both LEDs of the circle adjacent to each other An LED ring lighting device characterized in that the direction of inclination is reversed. 3. A plurality of LEDs arranged concentrically around an opening provided in the center, and an LE for irradiating inspection light onto a workpiece when performing image inspection using an image processing technique.
In the D-ring illumination, all the LEDs on the same circle are mounted so as to be inclined such that their optical axes have substantially the same mounting angle while alternately turning in the tangential direction of the circle. LED ring lighting. 4. The LED ring illumination according to claim 1, wherein the workpiece has a rotating body shape, and an axis of rotation of the workpiece passes through the center of the circle. Where E is the distance to the inspection site, r is the radius at the inspection site, and p is the radius distance from the center of the circle to each LED, the mounting angle θ is: tan θ = r (p ² −r ² ) ^{1 /} An LED ring illumination, which is set at an angle of ² / Ep. 5. L according to any one of claims 1 to 4,
ED ring illumination; a camera for imaging a workpiece through an opening of the LED ring illumination; and image processing means for processing an inspection image captured by the camera and performing a predetermined inspection on the surface of the workpiece. An image inspection apparatus, characterized in that: