JP2021105574A - Ultraviolet radiation device - Google Patents

Abstract

To provide an ultraviolet radiation device emitting ultraviolet, and an ultraviolet flaw detection device irradiating the surface of an inspection target with ultraviolet to analyze a surface state of the inspection target, the ultraviolet radiation device capable of achieving, by reducing energy loss, using smaller quantity of LEDs, high ultraviolet radiation ultraviolet intensity and even ultraviolet radiation ultraviolet intensity distribution in radiation range of an irradiated surface, and improving the accuracy of ultraviolet flaw detection.SOLUTION: An ultraviolet radiation device 1 comprises: an ultraviolet LED 2 for irradiating an irradiated surface; and a lens 10 for condensing light on the irradiated surface. The lens 10 includes a hole 12 or a coating part 52. The lens 10 is located between the ultraviolet LED and the irradiated surface, which is located with a certain distance from the lens 10 in a vertical direction. The lens 10 is formed so as to convert beams h, i, j, k passing through the lens so that a region M is irradiated with the beams, and is further formed so that a region L substantially overlapping with the region M is irradiated with light passing through the hole 12 of the lens 10.SELECTED DRAWING: Figure 1

Description

The present invention relates to an ultraviolet irradiation device that irradiates ultraviolet rays and an ultraviolet flaw detector that irradiates the surface of an object to be inspected with ultraviolet rays to analyze the surface state of the object to be inspected. The present invention relates to an ultraviolet irradiation device used for exciting a phosphor such as penetrant inspection.

As a flaw detection inspection on the surface of an object to be inspected such as a steel material, a magnetic particle flaw detection test and a penetrant flaw detection test, which are a kind of non-destructive inspection method, are known. In the magnetic particle inspection test, a magnetic powder or a magnetic powder solution containing magnetic powder is applied to the surface of the object to be inspected, and a magnetic field is applied to the object to be inspected to magnetize the object to be inspected. Since the magnetic flux is concentrated on defects such as cracks on the surface of the object to be inspected, the magnetic powder is attracted to the magnetic flux and an instruction pattern by the magnetic powder is formed. Then, the defect is inspected by observing this magnetic particle instruction pattern. The magnetic particle inspection includes a fluorescent magnetic particle inspection using a fluorescent magnetic powder containing a phosphor in the magnetic powder in order to improve the defect detection accuracy.

On the other hand, in the penetrant inspection test, first, the penetrant is applied to the surface of the object to be inspected to allow the penetrant to penetrate into defects such as cracks on the surface. Next, the excess penetrant adhering to the surface is removed, the developer powder is applied to the surface, and the penetrant permeating the defect is sucked out to the surface by a capillary phenomenon. Then, the defect is inspected by observing the permeation instruction pattern by the sucked penetrant. The penetrant inspection includes a fluorescent magnetic particle flaw detection test using a fluorescent penetrant containing a phosphor in order to improve the accuracy of defect detection.

When a fluorescent magnetic powder or a fluorescent penetrant is used in a magnetic particle flaw detection test or a penetrant flaw detection test, it is necessary to irradiate an object to be inspected with ultraviolet rays to excite the fluorescent material contained in the fluorescent magnetic powder or the fluorescent penetrant. As an ultraviolet irradiation device that irradiates ultraviolet rays, one that uses an ultraviolet LED (Light Emitting Diode) as a light source is known.

Due to the directivity of the LED, the ultraviolet intensity is weakened near the outer edge of the irradiation range. Therefore, there is a problem that the detection of defects such as cracks on the surface of the object to be inspected varies, and the inspection accuracy is lowered. In other words, there is a problem that it is difficult to obtain a uniform light distribution. Here, the uniform light distribution range refers to a range in the field of ultraviolet flaw detection that secures an ultraviolet intensity of a certain level or higher to the extent that scratches can be found. As one of the countermeasures, it is conceivable to obtain a high ultraviolet radiation intensity and a uniform ultraviolet radiation ultraviolet intensity distribution by arranging many LEDs on a line and using it as a light source. There has been a problem that it is difficult to obtain and that a large number of LEDs are required, which leads to an increase in cost.

Therefore, in Patent Document 1, a plurality of light emitting units having a plurality of LED elements mounted in a rectangular grid pattern on a substrate are provided, and lenses provided in the plurality of light emitting units are further provided, and the lenses are used with each other. Discloses a light emitting device that is connected to each other as a lens array that is an aggregate of these lenses, and since the light emitting portions are rectangular, the light emitting devices are arranged at different angles.

The technique described in Patent Document 1 can obtain a uniform light distribution to some extent by using the above-mentioned light guide plate or the like, but as long as a lens is used, energy loss due to reflection and transmittance occurs. Is inevitable. Further, in Patent Document 1, there is a loss in that the outer edge of the light emitting device is irradiated with light having a intensity equal to or less than uniform.

Japanese Unexamined Patent Publication No. 2018-22884

In the technique of Patent Document 1, it is considered to some extent that the ultraviolet radiation intensity of the LED is the strongest at the center (zero angle), and it is difficult to obtain a uniform light distribution due to the directional characteristic of the LED that decreases as the angle increases. ing. However, in the field of ultraviolet flaw detectors, it is said that in the irradiation range through the LED lens, the ultraviolet intensity of the outer edge portion is weakened, so that the outer edge portion cannot be used for inspection, resulting in energy loss. There's a problem. In the disclosure of Patent Document 1, a circular light distribution is realized, and although the ultraviolet intensity of the central portion of the light distribution is sufficiently secured, the ultraviolet intensity is sufficiently secured at the outer edge portion of the light distribution. The problem of not having it still remains. The technique of Patent Document 1 has not sufficiently shown a solution to this problem.

Further, there is a problem that when light is incident on the lens and light is emitted from the lens, the light is reflected and a loss occurs. In addition, there is a problem that loss occurs when transmitting through the lens. Since the technique of Patent Document 1 collects light by a lens, these losses occur.
Therefore, in the ultraviolet LED irradiation device, it has been desired to develop a lens that can realize uniform light distribution in a wide range without these losses.

An object of the present invention is an ultraviolet radiation flaw detector that irradiates the surface of an object to be inspected with ultraviolet rays to analyze the surface condition of the object to be inspected. It is an object of the present invention to provide an ultraviolet irradiation device capable of realizing a distribution and improving the accuracy of an ultraviolet flaw detection inspection.

In order to solve the above problems, the ultraviolet irradiation device of the present invention is provided with an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a lens that collects light on the irradiated surface, and irradiates the object to be inspected with ultraviolet rays. In an ultraviolet irradiation device for ultraviolet flaw detection that irradiates
The lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
The lens also has a hole in the center of the lens.
Further, the lens has a region in which the beam passes through the hole and directly irradiates on the irradiated surface and a region in which the beam passes through the lens and irradiates on the irradiated surface using the ultraviolet LED as a light source. , The beam is formed to be transformed so that all or part of it overlaps.

Further, it is provided with an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a linear Fresnel lens having the same function as a cylindrical lens that concentrates on the irradiated surface, and irradiates the object to be inspected by irradiating the ultraviolet rays. In the ultraviolet irradiation device
The linear Fresnel lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is characterized by having a slit-shaped hole in the central portion thereof.

Further, the ultraviolet irradiation device of the present invention includes an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a lens that collects light on the irradiated surface, and irradiates the object to be inspected by irradiating the ultraviolet rays. In
The lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is provided with a coating portion in the central portion thereof.
Further, in the lens, a region where the beam passes through the coating portion and irradiates on the irradiated surface and a region where the beam passes through the lens and irradiates on the irradiated surface are formed by using an ultraviolet LED as a light source. It is characterized in that the beam is formed so as to be transformed so that all or part of it overlaps.

Further, the ultraviolet irradiation device of the present invention includes an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a linear Frenel lens having the same function as a cylindrical lens that collects light on the irradiated surface, and irradiates the ultraviolet rays. In the ultraviolet irradiation device that irradiates the object to be inspected,
The linear Fresnel lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is characterized in that a slit-shaped coating portion is provided in the central portion thereof.

Further, the ultraviolet irradiation device is characterized by including an ultraviolet transmission protection filter.

The ultraviolet irradiation device of the present invention is provided with an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a lens that collects light on the irradiated surface, and irradiates the object to be inspected by irradiating the irradiated surface for ultraviolet flaw detection. In the ultraviolet irradiation device
The lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
The lens also has a hole in the center of the lens.
Further, the lens has a region in which the beam passes through the hole and directly irradiates on the irradiated surface and a region in which the beam passes through the lens and irradiates on the irradiated surface using an ultraviolet LED as a light source. Since the beam is formed so as to be converted so that all or part of the light overlaps, when an ultraviolet LED light source having the same output is used, a hole is formed on the irradiated surface. The light that has passed through is directly irradiated, and the light that has passed through the lens and is focused is reinforced, so that high ultraviolet radiation intensity in the irradiation range of the irradiated surface can be ensured. In addition, it is possible to realize uniform light distribution in which the distribution of the ultraviolet intensity becomes uniform while ensuring the ultraviolet intensity of a certain level or more in the irradiation range, and it is possible to improve the energy efficiency and the accuracy of the flaw detection inspection. can.

Further, according to the ultraviolet irradiation device of the present invention, an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a linear Frenel lens having the same function as a cylindrical lens that collects light on the irradiated surface are provided to emit ultraviolet rays. In an ultraviolet irradiation device that irradiates an object to be inspected by irradiating it
The linear Fresnel lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, since the lens is characterized by having a slit-shaped hole in the central portion thereof, the lens is directly irradiated with ultraviolet light through the slit-shaped hole in the irradiation range, and the lens is in the vicinity of the irradiation range. Since it has a function of condensing light, it is possible to realize a high-intensity and long strip-shaped uniform light distribution, improve energy efficiency, and improve the accuracy of flaw detection inspection.

Further, the ultraviolet irradiation device of the present invention includes an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a lens that collects light on the irradiated surface, and irradiates the object to be inspected by irradiating the ultraviolet rays. In
The lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is provided with a coating portion in the central portion thereof.
Further, in the lens, a region where the beam passes through the coating portion and irradiates on the irradiated surface and a region where the beam passes through the lens and irradiates on the irradiated surface are formed by using an ultraviolet LED as a light source. Since the beam is formed so as to be converted so that all or part of it overlaps, when an ultraviolet LED light source having the same output is used, the coated portion is covered on the irradiated surface. The light that has passed through is irradiated, and the light that has passed through the lens and is focused is reinforced, so that high ultraviolet radiation intensity in the irradiation range of the irradiated surface can be ensured. In addition, it is possible to realize uniform light distribution in which the distribution of the ultraviolet intensity becomes uniform while ensuring the ultraviolet intensity of a certain level or more in the irradiation range, and it is possible to improve the energy efficiency and the accuracy of the flaw detection inspection. can.

Further, the ultraviolet irradiation device of the present invention includes an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a linear Frenel lens having the same function as a cylindrical lens that collects light on the irradiated surface, and irradiates the ultraviolet rays. In the ultraviolet irradiation device that irradiates the object to be inspected,
The linear Fresnel lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, since the lens is characterized by having a slit-shaped coating portion in the central portion thereof, ultraviolet light passes through the slit-shaped coating portion and is irradiated while maintaining the ultraviolet intensity in the irradiation range, and the lens is irradiated. Since it has a function of condensing light in the vicinity of the irradiation range, it is possible to realize a high-intensity and long strip-shaped uniform light distribution, improve energy efficiency, and improve the accuracy of flaw detection inspection.

Further, since the ultraviolet irradiation device of the present invention is provided with an ultraviolet transmission protection filter, it is possible to cut visible light, and the working environment is improved as compared with the case where visible light is irradiated. , It can contribute to the prevention of oversight of scratches by inspectors due to visible light.

It is the schematic which showed an example of the ultraviolet irradiation apparatus which concerns on this embodiment, the locus of an irradiated beam, and its irradiation range. It is the schematic which focused on the beam which passes through a hole among the beams irradiated by the ultraviolet flaw detector of FIG. It is a schematic diagram focusing on the beam passing through a lens among the beams irradiated by the ultraviolet flaw detector of FIG. 1. It is a figure which showed the lens used for the ultraviolet ray flaw detector of FIG. It is the schematic which showed the ultraviolet ray flaw detection apparatus which concerns on this embodiment, the locus of an irradiated beam, and other examples of the irradiation range. It is a figure which showed an example of the linear Fresnel lens used in the ultraviolet flaw detector of FIG. It is a figure in which a plurality of ultraviolet irradiation devices provided with a plurality of ultraviolet LEDs and linear Fresnel lenses in the present embodiment are arranged in series. As another example in this embodiment, a lens provided with a coating portion is shown.

The details of the embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an example of an ultraviolet irradiation device according to the present embodiment, a trajectory of the beam, and an irradiation range. FIG. 2 is a lens 10 of the beams irradiated by the ultraviolet flaw detector of FIG. 1, which will be described later. It is a schematic diagram focusing on the beam passing through the hole portion 12. FIG. 3 is a schematic view focusing on the beam irradiated by the ultraviolet flaw detector of FIG. 1, which passes through the lens 10 and does not pass through the hole 12. 4 (X-1), (X-2), and (X-3) are views showing a top view, a side view, and a cross-sectional view of the lens 10, respectively. FIG. 5 is a schematic view showing an example in which a linear Fresnel lens having a cylindrical lens function is used as another example of the ultraviolet irradiation device according to the present embodiment, a trajectory of the beam, and an irradiation range. be. 6 (X-1) to 6 (X-3) show a top view, a side view, and a front view of the linear Fresnel lens 30, respectively. The saw-shaped cross-sectional portion of the surface of the linear Fresnel lens 30 is not shown in part. FIG. 7 shows another example of the ultraviolet irradiation device according to the present invention, in which a plurality of examples of FIG. 5 are arranged side by side as the ultraviolet irradiation device. FIG. 8 shows an example of the ultraviolet irradiation device in the present invention having a coating portion instead of the hole portion.

When the fluorescent magnetic powder or the fluorescent penetrant is used in the magnetic particle flaw detection test or the penetrant flaw detection test, the ultraviolet irradiation device 1 irradiates the object to be inspected with ultraviolet rays to excite the phosphor of the fluorescent magnetic powder or the fluorescent penetrant contained therein. The surface of the object to be inspected is irradiated with ultraviolet rays. In the present disclosure, for the sake of explanation, the inspection table 3 is shown as the irradiated surface. The ultraviolet irradiation device for the ultraviolet flaw detector according to the present embodiment is housed in a storage box 4 and includes an ultraviolet LED 2 that irradiates with ultraviolet rays, a lens 10 as a condensing lens, a linear Fresnel lens 30, and the like. In the following, for convenience of explanation, the inspection table 3 side of FIGS. 1 to 5 is on the bottom, the ultraviolet LEDs 2 and 22 are on the top, and the front side and the back side of each of FIGS. I will call it the back. Hereinafter, a specific configuration of the ultraviolet irradiation device for the flaw detector of the present disclosure will be described.

The ultraviolet irradiation device 1 further surrounds the ultraviolet LED 2, a lens 10 provided as a condensing lens, a linear Fresnel lens 30, and the like, and further includes storage boxes 4 and 21 having an ultraviolet outlet for emitting ultraviolet rays emitted from the ultraviolet LED 2. You may prepare. It is preferable to dispose an ultraviolet transmission filter capable of blocking visible light at the ultraviolet emission port. This ultraviolet transmission filter cuts a small amount of visible light emitted from the ultraviolet LED 2 in the wavelength range of visible light, approximately 400 nm to 700 nm, and defects detected in the object to be inspected are cut with a grinder or the like. When inspecting the metallic luster surface of the surface of the object to be inspected, the inspection work can be improved by preventing the visible light from being reflected on the metallic luster surface and making the worker dazzle.

As shown in FIG. 1, the lens 10 is a lens that collects the light emitted from the ultraviolet LED 2 toward the inspection table 3. It is located between the ultraviolet LED 2 and the inspected table 3 in the vertical direction, and when an inspected object (not shown) is placed on the inspected table 3, the surface of the inspected object is irradiated, and the surface is strictly. Is the surface to be irradiated, but for convenience of explanation, this is replaced with the inspection table 3 and the surface of the inspection table 3 is described as the surface to be irradiated. This is because the surface to be irradiated is a virtual flat surface, and the object to be inspected is not necessarily a flat surface. The object to be inspected and the inspection table 3 (not shown) are located at a predetermined distance from the lens 10 in the vertical direction.

Further, the trajectory of the light beam and the irradiation range will be described in detail with reference to FIG. For convenience, beams h, i, j, k and beams α, β are taken up as light rays emitted from the ultraviolet LED 2 and passing through the lens 10. The central axis γ is the central axis of the light of the ultraviolet LED 2, and is a straight line extending in the vertical direction from the ultraviolet LED 2. The beams h and k are the outermost rays that can be designed to pass through the lens. The beams i and j are the light rays that pass through the innermost side of the lens among those that the lens 10 can change the direction of the light rays.

The beams α and β are virtual lines showing the same locus as the light rays passing through the outermost part 12 of the hole portion 12 of the lens 10. The above beams h, i, j, k and beams α, β are above not only in the XX direction cross section of FIG. 1 (Y), but also in the YY direction cross section and other radial cross sections. Rays at the same position as defined in are referred to by the same sign. The area L is the range in which the bundle of beams emitted from the ultraviolet LED 2 surrounded by the beam α and the beam β passes through the hole of the lens 10 and directly irradiates the inspection table 3 which is the irradiated surface. .. Further, the region M shown in FIG. 3 is a region irradiated by the beam surrounded by the beams i, j, h, and k, and is a region irradiated only by the light rays that convert the line of sight of the lens 10. The shapes of the outer edges of the regions L and M may differ depending on the arrangement of the LED elements of the ultraviolet LED used.

The ultraviolet irradiation device 2 and its irradiation range will be described in more detail with reference to FIG. It is preferable that the region L and the region M substantially overlap. That is, it is most preferable that the beam α and the beam h form an intersection on the irradiated surface. It is most preferable that the beam β and the beam k also form an intersection on the irradiated surface. By using the lens 10 that converts the trajectory of the beam in this way, the bundle of beams that have passed through the lens 10 and are surrounded by the beams h, i, j, and k and irradiate the region M is the ultraviolet intensity of the region L. It will be irradiated in a form that complements the shortage of light, and a wider range can be made a uniform light distribution range by a lower intensity ultraviolet LED or a smaller number of ultraviolet LEDs. In order to obtain a wider range of high-intensity ultraviolet light in the irradiation range, the innermost light beam of the beams such as beams i and j that pass through the lens and irradiate the region M is refracted toward the central axis γ side, and the region L is refracted. The outer edge on the opposite side of the lens 10 (near the intersection of h and α in FIG. 1) is irradiated, and the refraction direction is gently adjusted as the outer beam becomes, and the beam passing through the lens 10 is bored in the radial direction. It has two cross sections, a left cross section 15 and a right cross section 16, straddling the portions, and it is preferable that the beam passing through these two cross sections irradiates the entire region L so as to overlap. By overlapping the light passing through the left and right sides of the cross section of the lens in this way, it is possible to irradiate ultraviolet rays with uniform light distribution and higher intensity. However, the present invention is not limited to this embodiment, and the irradiation range of the beam passing through the hole 12 and the irradiation range of the beam passing through the lens 10 and refracting are mostly on the irradiated surface separated by a predetermined distance. As long as they overlap, high ultraviolet intensity can be secured in the overlapping portion in the irradiation range, which is preferable. However, if a lens that does not irradiate a beam that does not pass through the hole 12 is used in the vicinity of the central axis γ, it is not preferable because sufficient ultraviolet intensity in the central portion of the irradiation range cannot be secured. At least, the lens 10 in which the beams i, j, etc. irradiate the vicinity of the central axis γ and the region M has an irradiation range in which a hole is not formed in the central portion ensures sufficient ultraviolet intensity. Moreover, it is preferable from the viewpoint of widening the uniform light distribution range.

The virtual lines α and β are straight lines that are the same as the locus of the outermost beam of the beam radiated in a conical shape from the center line γ, and are the angles formed by the virtual line α and the central axis γ and the virtual line β and the central axis γ. θ is preferably 5 to 30 degrees in relation to the directional characteristics. If it is 5 degrees or less, the effect of having the hole 12 is not so much obtained, and if it is 30 degrees or more, the beam passing through the lens is relative to the beam passing through the hole 12 in relation to the directivity. Since the intensity becomes too weak, it becomes impossible to maintain a uniform intensity in the irradiation range.

It should be noted that, in FIGS. 1 to 3, the beams h, i, j, k, the virtual lines α, β, and the central axis γ have been used for explanation. This has been described by showing FIG. 1 (X), FIG. 2 (X), and FIG. 3 (X) as cross-sectional views taken along the line XX with the X direction of FIG. 1 (Y) as the width direction. For example, in the Y direction of FIG. 1 (Y), the points described so far for the beams h, i, j, k, the virtual lines α, β, and the central axis γ are the same. That is, as long as it is in the radial direction, the above description holds true regardless of the cross section taken in any direction. This is because a circular lens is used for the lens 10.

Next, the lens 10 will be described with reference to FIG. Although the lens 10 is a linear Fresnel lens, it is referred to as a lens 10 for the sake of explanation. The surface 14 of the lens 10 has a saw-shaped cross section as shown in the enlarged portion of (X-3) which is the xx cross section of FIG. 4 (X-1). In FIG. 4 (X-1), a required number of saw-shaped convex portions are formed in an annular shape in this cross-sectional view. Except for the enlarged portion of (X-1) to (X-3) in FIG. 4, the saw-shaped portion is not shown.

Further, if the thickness of the lens 10 is 0.3 mm or less, it is practically difficult to manufacture, and if it is 2.0 mm or more, light is easily reflected in an unintended direction due to reflection by the cross section of the hole portion 12. On the other hand, a thickness of 0.3 mm to 2.0 mm is suitable because there is no reflection due to the cross section of the hole 12 and efficient irradiation can be performed. Further, it is preferable to use a linear Fresnel lens for the lens 10 in that the thickness of the lens can be reduced. In the lens 10, instead of the hole portion 12, a coating portion provided with an antireflection film may be provided at the same position as the hole portion 12. Even in this case, the same effect as that of providing the hole portion 12 can be obtained. By applying the antireflection film to the central surface of the lens 10, the reflectance of this portion is lowered, so that the ultraviolet intensity of the beam passing through the coating portion is maintained, which is preferable. The application of the antireflection film itself is based on a known technique.

Next, while showing FIG. 5, the linear Fresnel lens 30, which is another example of the ultraviolet flaw detector according to the present embodiment, will be described in detail.

The ultraviolet irradiation device 20 includes an ultraviolet LED 22 and a linear Fresnel lens 30 as a condensing lens. A storage box 21 that surrounds the ultraviolet LED 22 and the linear Fresnel lens 30 and has an ultraviolet emitting port that emits ultraviolet rays emitted from the ultraviolet LED 22 may be further provided. It is preferable to dispose an ultraviolet transmission filter capable of blocking visible light at the ultraviolet emission port. This ultraviolet transmission filter cuts a small amount of visible light emitted from the ultraviolet LED 22 in the wavelength range of visible light, approximately 400 nm to 700 nm, and defects detected in the object to be inspected are cut with a grinder or the like. When inspecting the metallic luster surface of the surface of the object to be inspected, the inspection work and inspection accuracy are greatly improved by preventing the visible light from being reflected on the metallic luster surface and causing the worker to dazzle and overlook the defect. be able to.

The linear Fresnel lens 30 is a lens that collects the light emitted from the ultraviolet LED 22 toward the inspection table 23. It is located between the ultraviolet LED 22 and the inspected table 3 in the vertical direction, and when an inspected object (not shown) is placed on the inspected table 3, the surface of the inspected object is irradiated, and the surface is strictly. Is an irradiated surface, but for convenience of explanation, this will be replaced with an inspection table 23, and the surface of the inspection table 3 will be described as an irradiated surface. This is because the surface to be irradiated is a virtual flat surface, and the object to be inspected is not necessarily a flat surface. The object to be inspected and the inspection table 23 (not shown) are located at a predetermined distance from the lens 10 in the vertical direction. The linear Fresnel lens 30 has a function of distributing light as an elongated irradiation range similar to that of a cylindrical lens, which is produced by a known technique for producing a linear Fresnel lens.

Further, the trajectory of the light beam and the irradiation range will be described in detail with reference to FIG. FIG. 5 (X) is a view showing a cross section of FIG. 5 (Y) in the X direction. For convenience, the beams q, r, s, t and the beams v, w are taken up as light rays emitted from the ultraviolet LED 22 and passing through the linear Fresnel lens 30. The central axis γ is also the central axis of the light of the ultraviolet LED 22, and is a straight line extending in the vertical direction from the ultraviolet LED 22. The beams q and t are the outermost rays that can be used in design. The beams r and s are the light rays that pass through the innermost side of the linear Fresnel lens 30 among those that the linear Fresnel lens 30 can change the direction of the light rays. The beams v and w are light rays that pass through the outermost part of the hole 41 of the linear Fresnel lens 30. That is, the region A surrounded by the beams v and w does not pass through the main body of the linear Fresnel lens 30, but passes through the hole 41 of the linear Fresnel lens 30, and the beam emitted from the ultraviolet LED 22 directly passes through the inspection table 23. It is the range to irradiate. Further, the region B is a region surrounded by the beams q, r, s, and t, and is a region irradiated by the light beam that converts the line of sight of the linear Fresnel lens 30. The definitions of the beams q, r, s, t, v, and w are the ZZ cross section and the ZZ cross section in the width direction of the lens 30 and its irradiation region A to B, for example, FIG. 5 (Y). It does not change in the cross section of other straight lines that are in parallel positions.

It is preferable that the region A substantially overlaps with the region B. In this case, the area A and the area B are substantially the same range. Even if they do not overlap, it is preferable that at least the region A is within the range of the region B. By making the beam bundle a convertible lens in this way, it was directly irradiated by the beam bundle passing through the hole 41 of the linear Fresnel lens 30 in the range from beam v to w having sufficient ultraviolet intensity. In region A, when the UV intensity is below the required level, a bundle of beams illuminating the region surrounded by the beams q, r, s, t, which is the light passing through the linear Fresnel lens 30, complements this. Will play a role in In order to play a complementary role, region B needs to cover all region A. By using the linear Fresnel lens 30 that converts the beam in this way, the region B is surrounded by the beams q, r, s, and t that have passed through the linear Fresnel lens 30 in the portion where the ultraviolet intensity of the region A is insufficient. The bundle of beams to be irradiated is irradiated in a form that complements the lack of ultraviolet intensity in this region L, and a wider range is set as a uniform light distribution range by a lower intensity ultraviolet LED or a smaller number of ultraviolet LEDs. It becomes possible to do.

The beams v and w are the outermost beams that irradiate the region A, and the angle Σ formed by the virtual line v and the central axis γ and the virtual line w and the central axis γ is 5 to 30 degrees in relation to the directional characteristics. It is preferable to have. If the angle Σ is 5 degrees or less, the effect of providing the hole 41 is not sufficiently obtained in practical use, and if it is 30 degrees or more, it becomes difficult to obtain uniform light distribution in the width direction, which is not preferable.

The beam r and the beam s that irradiate the region B, that is, the beam that passes through the innermost vicinity of the lens among the beams that irradiate the region B and irradiates the beam, receives the central axis γ from there when passing through the lens. The beam is transformed so as to illuminate the vicinity of the outside of the region A on the opposite side of the beam. Then, the refraction direction of the beam passing through the lens is gradually adjusted as the passing point of the lens becomes outside the lens. As a result, the beam passing through the outermost side of the lens does not exceed the central axis γ after passing through the lens, and is on the opposite side of the central axis γ from the portion through which the beam of the lens has passed, near the outside of the region A. Irradiate. It is preferable that the linear Fresnel lens 30 that converts the beam in this way is formed.

It will be described in more detail with reference to FIG. The plane through which both the central axis γ and the YY straight line in FIG. 5 (Y) in the longitudinal direction of the hole 41 orthogonal to the central axis γ pass is defined as the virtual plane 60. The beam q passing through the left cross section 42 with the virtual plane 60 as a boundary irradiates the outermost region irradiated by the beam v passing through the hole 41 on the left side of the virtual plane 60, and gradually adjusts the degree of refraction. By doing so, the beam is converted so as to irradiate beyond the virtual plane 60 to the right end, and finally, the same part as the beam w irradiates at the right end like the beam r is irradiated. do.

Similarly, the light passing through the right cross section 43 irradiates beyond the virtual plane 60 to the left side. First, the outermost region to be irradiated by the beam w passing through the hole 41 on the right side of the virtual plane 60 is irradiated, and the refraction is gradually adjusted so as to irradiate beyond the virtual plane 60 to the left end. It is preferable that the linear Fresnel lens 30 is converted so that the beam is converted into a beam, and finally the beam s irradiates the same portion as the beam v irradiates.

An ultraviolet irradiation device provided with a linear Fresnel lens 30 that converts in this way can realize uniform light distribution in a wide range with less energy loss and less unevenness. Most preferably, the region B and the region A overlap as the same region as possible. With this shape, energy loss is small, there is no unevenness, and high intensity and uniform light distribution can be realized. However, the present invention is not limited to this embodiment, and is limited to the irradiation range of the beam that passes through the linear Fresnel lens 30 and is refracted, that is, the irradiation range of the beam that passes through the region B and the hole 41 and travels straight without refraction. It is preferable as long as it overlaps with a certain region A. However, in the region B, if a lens that does not irradiate the central portion near the central axis γ is used, sufficient ultraviolet intensity cannot be secured in the irradiation range, which is not preferable. At least, it is sufficient to form the linear Fresnel lens 30 so that the beam r, s, etc. irradiate the vicinity of the central axis γ and the irradiation range has no hole in the central portion of the region B. It is preferable from the viewpoint of ensuring uniform light distribution and ensuring uniform light distribution.

The relationship between the beams q, r, s, t, v, w and the central axis γ in the above description will be described with reference to FIG. 5 (X), and FIG. 5 (X) is shown in FIG. 5 (Y). Although the cross-sectional view in the X direction is schematic, the relationship as described above is the same even in the cross-sectional view in the Z direction of FIG. 5 (Y), for example. Even if this shifts toward the back and front of FIG. 5 (X), the relationship of the beams shown in FIG. 5 (X) as described above does not change.

Next, the shape of the linear Fresnel lens 30 will be described with reference to FIG. As shown in FIG. 6 (X-1), a slit-shaped hole 41 is provided at the center of the linear Fresnel lens 30 in the width direction. The hole 41 may be rectangular or rounded, but it is preferable that the hole 41 is linear to some extent in the longitudinal direction. As shown in (X-2) and (X-3), the linear Fresnel lens 30 is formed to be thin.

Next, the advantages of the lens 10 and the linear Fresnel lens 30 which are examples of the embodiment according to the present invention will be described in detail while comparing with the conventional lens. When condensing light using a normal lens having no holes as in the conventional case, when a beam is incident on the lens from an ultraviolet light source, it is first reflected on the lens surface, so that energy loss occurs. When the incident angle is 0 degrees, the reflectance is about 4%. Similarly, when it is emitted from the lens, it is about 4%. Therefore, the energy loss due to the reflection generated by the ultraviolet rays passing through the lens is about 8%. When Nichia's NVSU333A is used as the UV LED light source, the reflectance reaches about 8%, which is about twice as high when the incident angle is 42 degrees. When a so-called half-angle beam with a relative luminous intensity of 50 percent due to directivity is used, the reflectance reaches about 17 percent. When all the beams up to the half-value angle are used, the reflectance at an incident angle of 0 to 60 degrees, that is, the energy loss is about 7.5%. The total energy loss at the time of incident and at the time of exit is about 15%.

There is also an energy loss due to the transmittance of the lens. When a normal lens is used, the transmittance of ultraviolet rays tends to be lower than that of visible light. In addition, the material is deteriorated by ultraviolet rays, and the transmittance is further lowered. Therefore, the ultraviolet transmittance in the used state is set to around 85%. Due to the loss at the time of incident, about 85% of the energy remains, and by subtracting the transmittance, 85% of the energy remains. Therefore, in this case, the energy loss due to reflection and transmittance is 0.85 × 0.85 = 0.7225, and 72% of the energy remains. Therefore, as an energy loss, a loss of about 28% will occur. In the present embodiment, since the lens 10 and the linear Fresnel lens 30 are provided with the holes 12 and 41, the beam passing through the holes 12 and 41 directly irradiates the inspection table 3 which is the irradiated surface. .. Therefore, the energy loss due to the passage through the lens does not occur, and the energy loss is significantly reduced even when combined with the light passing through the lens.

In the present invention, it is assumed that uniform light distribution is realized when the ultraviolet radiation ultraviolet intensity is within the range of ± 10% of the average value of the ultraviolet radiation ultraviolet intensity over the entire irradiation surface of the irradiated surface. There is.

The dimensions of the irradiated surface and each region are not limited. The lens 10 and the linear Fresnel lens 30 are separated from the irradiated surface by a predetermined distance. When used in an ultraviolet flaw detector, this distance is about 300 mm to 1200 mm.

Here, typical dimensions and materials of the linear Fresnel lens 30 and the lens 10 of the present invention will be described. The length (pitch pt) of one side of each groove in the linear Fresnel lens 30 is about 0.1 to 0.3 mm. The size of each Fresnel surface and rise surface is such that the width of the Fresnel surface is about 0.15 mm to 0.40 mm and the height of the rise surface in the vertical direction is about 0.05 mm to 0.15 mm. These dimensions are not limited, and can be appropriately designed from the viewpoint of obtaining a uniform ultraviolet radiation and ultraviolet intensity distribution.

Further, since both the linear Fresnel lens 30 and the lens 10 are linear Fresnel lenses, the thickness of the lens can be made thin. By forming the thinness of these lenses to 0.3 mm to 2.0 mm, there are the following advantages. First, if it is 0.3 mm or less, it is practically difficult to manufacture, and if it is 2.0 mm or more, light is easily reflected in an unintended direction due to reflection by the cross section of the hole portion 12. On the other hand, a thickness of 0.3 mm to 2.0 mm is suitable because there is no reflection due to the cross section of the hole 12 and efficient irradiation can be performed. Further, it is preferable to use a linear Fresnel lens for the lens 10 and the linear Fresnel lens 30 in that the thickness of the lens can be reduced.

As the material of the linear Frenel lens 30 and the lens 10, a conventionally used transparent resin can be used, and an acrylic resin, an epoxy resin, a polycarbonate resin, a polyester resin, a styrene resin, an acrylic styrene copolymer resin, a cycloolefin polymer resin, etc. Silicon resin, fluororesin and the like are used, and these resins and a mold having an inverted shape of the Fresnel lens may be used for molding by a method such as a press molding method.

Next, an ultraviolet flaw detector as an example including a plurality of ultraviolet irradiation devices 20 according to the present embodiment will be described.
As shown in FIG. 7, the ultraviolet irradiation device 20 may be arranged side by side in a plurality of linear lines in the longitudinal direction of the object to be inspected. Billets and the like are often used as the object to be inspected, and in the case of an elongated object to be inspected, it is preferable to arrange the ultraviolet irradiation devices 20 in the longitudinal direction in this way. In FIG. 7, an ultraviolet irradiation device provided with five units such as an ultraviolet LED 22 and a linear Fresnel lens 30 is arranged side by side, and a uniform light distribution is provided on the left side of the third LED from the right side of the ultraviolet LED 22. .. The same applies to the left end of the ultraviolet flaw detector shown in FIG. Each beam is emitted from each ultraviolet LED 22, and the full-width edge of the ultraviolet light distribution that has passed through the linear Fresnel lens 30 is the light of the ultraviolet LED 22 arranged next to or further next to the ultraviolet LED 22 on the irradiated surface. It is preferably arranged so as to be substantially aligned with the axis. As a result, the light distribution of the ultraviolet LED 22 adjacent to the left side of the third LED from the right side over the entire region is superimposed, and a uniform ultraviolet radiation ultraviolet intensity distribution can be obtained.

Next, the coated portion will be described in detail with reference to FIG. As another example of the ultraviolet irradiation device of the present invention, FIG. 8 shows a coating on the surface of the holes 12 and 41 of the lens 10 and the linear Fresnel lens 30 in which an antireflection film is applied instead of the holes 12 and 41. It includes parts 52 and 53. The coating portions 52 and 53 are provided with antireflection films 50 and 51 on both sides of the lens, respectively. The portion not covered by the coating portion of the lens is referred to as the lens outer side 54 and the lens outer side 55. It is preferable to use AR coating technology for the antireflection films 50 and 51. That is, it is preferable that the antireflection film is made into a transparent thin film by vacuum-depositing magnesium fluoride or the like. The thickness of the antireflection film is one-fourth of the wavelength of light, and the reflectance is reduced by canceling out the reflected light of the thin film and the reflected light at the time of incident of the lens that is the base material in opposite phases. A known technique as an AR coating can be used, such as being able to increase the transmittance.
As shown in FIG. 8, the lens 10 is provided with the antireflection film 50 instead of the hole portion 12, the coating portion 52, and the antireflection film 51 is provided in the center in a slit shape instead of the hole portion 41 of the linear Frenel lens 30. By using the coating portion 53, the same phenomenon as when the light passing through the hole portion directly irradiates the irradiated surface can be realized by the coating portions 52 and 53, so that the light passing through the outer lenses 54 and 55 and the light passing through the lens outer side 54 and 55 can be realized. If the light passing through the coating portions 52 and 53 has the same irradiation region, the ultraviolet intensity is increased, and the lens 10 and the linear Frenel lens 30 have the hole portion 12 and the hole portion 41. If the configuration is the same as that of the above, the same effect can be obtained, which is preferable. All the lenses disclosed in FIG. 8 are described with reference to FIGS. 1 and 5 of the present disclosure, such that it is preferable to form the lens thinness to 0.3 mm to 2.0 mm. The configuration is exactly the same except for the holes. The antireflection film may be formed of a multilayer film, and may be an antireflection film other than AR coating by a known technique such as coating using a nanoparticle film.

Hereinafter, the present disclosure will be described in more detail and concretely with reference to Examples. However, the present disclosure is not limited to the following examples.

[Example]
In Example 1, the ultraviolet irradiation device 1 according to the present embodiment shown in FIG. 5 was used. That is, the ultraviolet irradiation device 1 includes an ultraviolet LED 2 that irradiates the irradiated surface with ultraviolet rays, and a linear Fresnel lens 30 that is a linear Fresnel lens that collects light so as to irradiate the irradiated surface. The linear Fresnel lens 30 is formed so that the beam passing through the lens 10 illuminates the region A and the beam passing through the hole 12 illuminates the region B. It has the features of the present invention, such as the ranges of regions A and B almost overlapping, and the thinness of the linear Fresnel lens 30 is 0.5 mm.

The linear Fresnel lens 30 used in the ultraviolet irradiation device 1 of the first embodiment is made of an acrylic resin, and the irradiated surface is located at a distance of 400 mm from the linear Fresnel lens 30 which is a linear Fresnel lens as a type. For the purpose of making the ultraviolet radiation intensity uniform in the irradiation range of the irradiation width of 200 mm in the width direction, which is the lateral direction in No. 5, the surface length is 40 mm, the thickness is t = 0.5 mm, and the pitch is pt = 0.2 mm. Made. The ultraviolet LED 2 used was of model NVSU233B-D4 and had a peak wavelength of 365 nm.

Regarding the ultraviolet irradiation device of Comparative Example 1, the linear Fresnel lens 30 is not provided with the hole 41, and is formed so as to irradiate the same range as the region B, which is the same range as that of Example 1. The lens was used. Other conditions are the same, such as a distance of 400 mm and the ultraviolet LED being model NVSU233B-D4.

<Evaluation method>
(Ultraviolet radiation ultraviolet intensity distribution test)
The ultraviolet radiation intensity distribution of the irradiated surface was measured when the ultraviolet irradiation devices of Example 1 and Comparative Example 1 were used. The ultraviolet radiation intensity distribution in the region of the irradiated surface 3 having an irradiation width of 200 mm located at a distance of 400 mm from each lens was measured. As a result, in Example 1, the ultraviolet radiation ultraviolet intensity is within the range of ± 10% of the average value of the ultraviolet radiation ultraviolet intensity over the entire irradiation width, and the ultraviolet intensity is the conventional average in the irradiation width. It was confirmed that the improvement was about 10% compared to the above. That is, it was confirmed that the ultraviolet intensity was made uniform and the intensity was increased.

On the other hand, in Comparative Example 1, the ultraviolet intensity distribution was also measured. As a result, in Comparative Example 1, in the irradiation width, a portion where the ultraviolet radiation ultraviolet intensity did not fall within the range of ± 10% of the average value of the ultraviolet radiation ultraviolet intensity over the entire irradiation width was observed, and the ultraviolet intensity became uniform. It was confirmed that it was not done. In addition, as a result of averaging the ultraviolet intensity in the irradiation width, it was confirmed that the ultraviolet intensity did not improve much as compared with the conventional case.

The present disclosure can be suitably used for an ultraviolet irradiation device that irradiates ultraviolet rays and an ultraviolet flaw detector provided with the ultraviolet irradiation device. However, the present disclosure is not limited to the embodiments and examples described above. The ultraviolet irradiation device of the present disclosure is useful for all tests and inspections that utilize ultraviolet rays, such as contamination check, leak inspection, and confirmation of degreasing cleaning. Further, the ultraviolet ray flaw detector of the present disclosure is not limited to the fluorescent magnetic particle flaw detector, and may be a penetration flaw detector that detects defects on the surface of the object to be inspected by using a fluorescent penetrant, and uses ultraviolet rays. It can be applied to any UV flaw detector that detects defects.

1 UV irradiation device 2 UV LED
3, 23 Inspection table
4, 21 Storage box 10 Lens 12, 41 Hole O, P cd Virtual line hi jk q r st Beam 30 Linear Fresnel lens
50, 51 Antireflection film 52, 53 Coating part 54, 55 Lens outer side 60 Virtual plane

Claims (5)

In an ultraviolet irradiation device for ultraviolet flaw detection, which comprises an ultraviolet LED that irradiates an irradiated surface with ultraviolet rays and a lens that collects light on the irradiated surface and irradiates an object to be inspected by irradiating the irradiated surface.
The lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
The lens also has a hole in the center of the lens.
Further, the lens has a region in which the beam passes through the hole and directly irradiates on the irradiated surface and a region in which the beam passes through the lens and irradiates on the irradiated surface using an ultraviolet LED as a light source. An ultraviolet irradiator, characterized in that the beam is formed to be transformed so that all or part of it overlaps. It is equipped with an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a linear frennel lens that has the same function as a cylindrical lens that concentrates on the irradiated surface, and irradiates the object to be inspected with ultraviolet rays. In the device
The linear Fresnel lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is an ultraviolet irradiation device characterized in that a slit-shaped hole portion is provided in a central portion thereof. In an ultraviolet irradiation device that includes an ultraviolet LED that irradiates an irradiated surface with ultraviolet rays and a lens that collects light on the irradiated surface and irradiates an object to be inspected by irradiating the irradiated surface.
The lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is provided with a coating portion in the central portion thereof.
Further, in the lens, a region where the beam passes through the coating portion and irradiates on the irradiated surface and a region where the beam passes through the lens and irradiates on the irradiated surface are formed by using an ultraviolet LED as a light source. An ultraviolet irradiator, characterized in that the beam is formed to be transformed so that all or part of it overlaps. It is equipped with an ultraviolet LED that irradiates the irradiated surface with ultraviolet rays and a linear frennel lens that has the same function as a cylindrical lens that concentrates on the irradiated surface, and irradiates the object to be inspected with ultraviolet rays. In the device
The linear Fresnel lens is located between the ultraviolet LED and the irradiated surface in the vertical direction.
The irradiated surface is located at a predetermined distance from the lens in the vertical direction.
Further, the lens is an ultraviolet irradiation device characterized in that a slit-shaped coating portion is provided in a central portion thereof. The ultraviolet irradiation device according to claim 1, wherein the ultraviolet irradiation device includes an ultraviolet transmission protection filter.

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