JP2006269199A - Light irradiation device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light irradiation device that allows a greater number of light beams to be incident through a light guide, that uniformalizes distribution of light emitted from the light guide to the maximum extent possible to be improved in accuracy of inspection. <P>SOLUTION: A bar-shaped light guide 6 is provided in one end of a case main body 5 made up of a plurality of case bodies 2, 3 and 4, while a light-emitting diode 7 is provided in the other end of the case main body 5. First and second lenses 8 and 9 are provided between the diode 7 and the light guide 6. An end face 6b on the light incidence side of the light guide 6 is formed into a round smooth surface, while an end face 6a on the light emitting side is formed into a round diffusing surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light irradiation apparatus, and more particularly to an improvement of a light irradiation apparatus applied to an inspection system that inspects a surface state of a component to be inspected by image processing.

In general, this type of inspection system is configured to irradiate light to a part to be inspected, capture the reflected light with a CCD camera or the like, and compare the imaged data of a normal part to determine the quality of the part to be inspected. Has been.
Recently, due to improvements and advancements in illumination light sources, small-sized light emitting diodes capable of obtaining a large light output have been used. For example, Japanese Patent Application Laid-Open No. 2004-111377 discloses light using such light emitting diodes. Irradiation devices have been proposed.

  This proposal is configured as shown in FIG. 6, for example. In the figure, A is a light irradiation device, and a case body D composed of a first case body B having a reduced diameter portion and an expanded portion, a second case body C, and a contraction of the first case body B. A light guide E made of a glass rod housed in the diameter portion, a light emitting diode F disposed at the bottom of the second case body C, and a first disposed between the light emitting diode F and the light guide E. , And second lenses G and H. The first and second lenses G and H are connected to and tightened between the first and second case bodies B and C using a spacer body and an O-ring. Is devised so that the respective central axes coincide with each other. In addition, each end surface of the light guide E is formed in a planar shape.

  This light irradiation apparatus is applied to an inspection apparatus J including a coaxial macro lens, a CCD camera, etc., for example, as shown in FIG. In this inspection apparatus J, for example, the coaxial macro lens portion is connected to the first cylindrical portion K1 extending horizontally, the second cylindrical portion K2 extending to the first cylindrical portion K1, and extending vertically. The beam splitter L is disposed in the second tubular portion K2 corresponding to the connecting portion of the tubular portion K1, and the objective lens M is disposed at the lower end of the second tubular portion K2. A CCD camera or the like (not shown) is disposed above the second cylindrical portion K2.

  In this apparatus, light having a spread emitted from the light-emitting diode F is shaped by the first lens G (changed to a substantially parallel light) and collected by the second lens H. The condensed light enters the light guide E and is emitted from the planar diffusion surface at the tip. The emitted light enters the beam splitter L via the first cylindrical portion K1 in the inspection apparatus J and is refracted vertically downward. The refracted light passes through the objective lens M and is irradiated on the inspection object P. The reflected light from the inspected object P again passes straight through the beam splitter L and is imaged as the inspected object P by a CCD camera or the like (not shown). This imaging data is compared with standard data stored in advance in a computer or the like, and the surface state (form, scratch, chipping, etc.) is inspected.

According to such an apparatus, since a current of 200 to 300 mA or more can flow through the light-emitting diode F, a significant increase in light output can be expected. Therefore, the illuminance of the surface on which the object P is placed is also high. The inspection accuracy can be increased and the inspection accuracy can be improved.
JP 2004-111377 A

However, in the above-described apparatus, although the light output can be increased, the light incident side end surface Eb of the light guide E is configured as a flat surface, and the light emission side end surface Ea is configured as a planar diffusion surface. For this reason, not only the light output emitted from the light guide E does not increase for the increase in the light output of the light emitting diode F, but also the light cannot be sufficiently dispersed and diffused on the emission surface, resulting in uneven illuminance. There's a problem.
That is, as shown in FIG. 8, when light parallel to the central axis of the light incident side Eb of the light guide E is incident, most of the incident light is light output. It is emitted from the side end face Ea. However, when the incident angle of light with respect to the central axis is 5 ° or more, the ratio of the light that is totally reflected by the end surface Eb and incident on the light guide E decreases, and the end surface Ea on the light emission side is flat. Even if it is configured as a diffusion surface, the amount of light emitted from the end face Ea is reduced. For this reason, as shown in FIG. 9, in the light amount distribution at a position 20 mm away from the end face Ea, the light amount is clearly reduced in the peripheral portion as compared with the central portion, and uneven illuminance is exhibited.
In addition, when the incident angle of the light to the end surface Eb of the light guide E is 18 ° or more, the incident light is totally reflected by the end surface Eb, and the light is not incident on the light guide E. As a result, the light output from the end surface Ea is also performed. It will not be done.
By the way, in such a light irradiation device, it is difficult to set the incident angle of light from the second lens H to the light guide E to be less than 5 ° at which total reflection does not occur because of the design of the device. Inevitable.

Therefore, for example, when applied to the inspection apparatus J shown in FIG. 7, as a result of uneven illuminance on the irradiated surface of the object P to be inspected, the reliability of image data obtained by a CCD camera or the like is lowered particularly in a portion with low illuminance. For this reason, there is a problem that the final inspection accuracy is impaired.
SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a light irradiating device that allows a large amount of light to be incident on a light guide and also makes the distribution of light emitted from the light guide as uniform as possible to improve inspection accuracy. It is to be.

  Therefore, in order to achieve the above-mentioned object, the present invention provides a case body composed of a plurality of case bodies, a rod-shaped light guide housed and arranged in one of the case bodies, and a light emitting diode arranged in the other of the case bodies. The light irradiation device includes a plurality of lenses disposed between the light emitting diode and the light guide in the case body, and guides light from the light emitting diode to the light guide by the action of the plurality of lenses. The light incident side end surface of the light guide is configured as a spherical smooth surface, and the light emission side end surface is configured as a spherical diffusion surface.

  According to a second aspect of the present invention, the light guide is composed of a glass rod, and a spherical diffusion surface is roughened by frosting or the like. The body is composed of an assembly of a plurality of optical fibers, and the end surface on the light incident side is formed into a spherical smooth surface, and the end surface on the light emission side is formed into a spherical diffusion surface.

  According to a fourth aspect of the present invention, the plurality of lenses are constituted by first and second lenses, and the first lens is a collimator for shaping the directivity of light having a spread from the light emitting diode. The second lens is a plate-shaped Fresnel lens that condenses the shaped light from the collimator lens and enters the light guide, and the fifth invention provides the second lens. Is composed of a plurality of Fresnel lenses.

  Furthermore, a sixth aspect of the present invention is characterized in that the case body is composed of a plurality of case bodies, and a plurality of lenses are positioned and held at the end portions of the respective case bodies.

  As described above, according to the present invention, the end surface on the light incident side of the light guide is configured as a spherical smooth surface having a predetermined curvature, and the end surface on the light emission side is configured as a spherical diffusion surface having a predetermined curvature. In addition, more light from the lens can enter the light guide, and the light can be dispersed by the lens effect to obtain almost uniform diffused light. For this reason, in the illuminance distribution in front of the spherical diffusion surface in the light guide, as shown in FIG. 5, the illuminance unevenness is remarkably improved as compared with the case of the prior art shown in FIG. Therefore, for example, when applied to an inspection apparatus including a coaxial macro lens, a CCD camera, etc., the object to be inspected can be illuminated with substantially uniform illuminance, so that the inspection accuracy can be further improved as compared with the prior art. It is possible to improve the reliability of the system.

  Next, a first embodiment of the present invention will be described with reference to FIG. In the figure, reference numeral 1 denotes a light irradiating device having a reduced-diameter storage portion 2a for storing a light guide to be described later at one end portion and a widening portion at the other end portion. A case body 5 including a case body 2, a second case body 3, and a third case body 4, a light guide body 6 housed in the housing portion 2 a of the first case body 2, and a third case body 4. , The first lens 8 disposed between the light emitting diode 7 and the end surface of the second case body 3, the end surface of the second case body 3, and the first case The second lens 9 is disposed between the end surface of the body 2 and an O-ring 10. Reference numeral 11 denotes a cable for supplying power to the light emitting diode 7 and the like.

The light guide 6 housed in the housing portion 2a of the first case body 2 is formed of, for example, a glass rod, and the end surface 6a on the light emission side has a spherical diffusion surface having a predetermined curvature, and the light incident side. The end surface 6b is formed in a spherical smooth surface having a predetermined curvature. By configuring the end face 6a as a spherical diffusing surface in this way, it is possible to form a substantially complete diffusing surface utilizing the properties of light and lens boundary surface refraction. Further, by configuring the end surface 6b to be a spherical smooth surface, the light is effectively incident on the light guide 6 even when the incident angle of the light from the second lens 9 to the light guide 6 becomes 5 ° or more. be able to. The end face 6a of the light guide 6 is roughened by, for example, frost processing.
The first lens 8 described above is configured by, for example, a collimator lens, and the directivity of light having a spread emitted from the light emitting diode 7 is shaped by the collimator lens. Further, the second lens 9 is configured by, for example, superposing two substantially plate-shaped Fresnel lenses. The second lens 9 condenses the substantially parallel light arranged by the first lens 8 and the light guide 6 Incident on the inner end face. The first and second lenses 8 and 9 are preferably formed of a resin material from the viewpoint of manufacturing cost, productivity, and weight reduction, but may be formed of glass or the like. In addition, a plurality of Fresnel lenses can be overlapped and one can be used.

A screw portion is formed on the outer peripheral surface of the expanded portion 2 b in the first case body 2 described above, and this screw portion is formed on the inner peripheral surface of one end portion 3 a in the second case body 3. Screwed and connected to the screw part. A screw portion is formed on the outer peripheral surface of the other end portion 3 b of the second case body 3, and this screw portion is formed on the inner peripheral surface of one end portion of the third case body 4. Screwed and connected to the screw part.
A heat radiating fin is formed on the outer peripheral surface of the case body 5 in order to efficiently dissipate heat generated by the light emitting diode 7.

  Next, a second embodiment of the present invention will be described with reference to FIG. The basic configuration of this embodiment is the same as that of the embodiment shown in FIG. 1, and the difference is that the light guide 6 is constituted by an assembly of a plurality of optical fibers. The end surface 6b on the light incident side is formed as a spherical smooth surface having a predetermined curvature as in the first embodiment, and the end surface 6a on the light emission side is formed as a spherical diffusion surface having a predetermined curvature. According to this embodiment, the same effect as that of the first embodiment can be expected.

  Next, an application example of the light irradiation apparatus 1 shown in FIG. 1 to the inspection apparatus J will be described with reference to FIG. First, the light irradiation device 1 is coupled to the inspection device J by inserting the storage portion 2a of the first case body 2 into the first cylindrical portion K1. In this state, when electric power is supplied to the light emitting diode 7 via the cable 11, the light emitting diode 7 emits light, and light having a spread is emitted. The directivity of this radiated light is shaped by the first lens 8, corrected and changed to substantially parallel light, and incident on the second lens 9. In the second lens 9, substantially parallel light is collected and is incident on the spherical smooth surface (end surface) 6 b of the light guide 6. In particular, since the end face 6b of the light guide 6 is configured as a spherical smooth surface, as shown in FIG. 4, even if the incident angle of light from the second lens 9 is 5 ° or more, the light guide 6 is efficiently incident. And since the front end surface (6a) of the light guide 6 is comprised by the spherical diffusion surface 6a which has a predetermined curvature, the substantially perfect diffusion surface using the property of light and interface refraction can be formed. . As shown in FIG. 5, the illuminance distribution in the front (for example, 20 mm) of the spherical diffusion surface 6a of the light guide 6 has less uneven illuminance than the conventional example shown in FIG. is doing.

The light properly diffused in this way reaches the beam splitter L via the first cylindrical portion K1, is reflected by the beam splitter L, travels vertically downward through the second cylindrical portion K2, and the objective lens M And is projected onto the inspection object P. The object P is irradiated with a substantially uniform illuminance. The light irradiated on the inspection object P is reflected, travels vertically upward through the second cylindrical portion K2, and reaches the beam splitter L. The reflected light travels straight without being reflected by the beam splitter L, enters a CCD camera (not shown), and the object P is imaged. This imaging data is compared with standard data stored in advance, and the quality of the surface state (scratches, chipping, etc.) of the inspection object P is determined.
According to this embodiment, since the light irradiation device 1 to the inspection device J are irradiated with light with less uneven illuminance onto the inspection object P as shown in FIG. 5, the surface state of the inspection object P is changed. High-accuracy and high-reliability inspection is possible with high-accuracy imaging.

  It should be noted that the present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist of the present invention. For example, the light irradiation apparatus of the present invention can be applied to apparatuses and systems other than the inspection apparatus shown in FIG. Further, the plurality of lenses are not limited to the collimator lens and the Fresnel lens as long as they have the function of shaping the light having a spread from the light emitting diode and further collecting the light. Further, the case main body can be constituted by two case bodies in addition to the three case bodies. Furthermore, although these case bodies are connected by screwing of the screw parts formed in each, it is also possible to employ connecting means other than screwing.

It is a sectional side view which shows the 1st Example of this invention. It is the sectional side view to which the principal part which shows the 2nd Example of this invention was expanded. It is a sectional side view which shows the example of application to the test | inspection apparatus of the light irradiation apparatus concerning this invention. It is a figure which shows the light incident of the light guide in the 1st Example of this invention, and the light emission condition. FIG. 5 is an illuminance distribution diagram according to FIG. 4. It is a sectional side view which shows a prior art example. It is a sectional side view which shows the application example to the inspection apparatus of a prior art example. It is a figure which shows the light incidence of the light guide in the prior art example, and the light emission condition. FIG. 9 is an illuminance distribution diagram according to FIG. 8.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light irradiation apparatus 2 1st case body 2a Storage part 2b Expansion part 3 2nd case body 4 3rd case body 5 Case main body 6 Light guide 6a Spherical diffusion surface 6b Spherical smooth surface 7 Light emitting diode 8 1st Lens 9 second lens

Claims (6)

  A case body composed of a plurality of case bodies, a rod-shaped light guide housed and disposed in one of the case bodies, a light emitting diode disposed in the other of the case bodies, and the case body between the light emitting diode and the light guide A light irradiation device that guides light from the light-emitting diode to the light guide by the action of the plurality of lenses, and the end surface on the light incident side of the light guide is spherically smoothed. A light irradiating apparatus characterized in that the end surface on the light emission side is formed as a spherical diffusion surface.   The light irradiation apparatus according to claim 1, wherein the light guide is formed of a glass rod, and the spherical diffusion surface is roughened by frosting or the like.   The light guide body is constituted by an assembly of a plurality of optical fibers, the light incident side end surface is formed as a spherical smooth surface, and the light emission side end surface is formed as a spherical diffusion surface. Light irradiation device.   The plurality of lenses are constituted by first and second lenses, the first lens is a collimator lens that shapes the directivity of light having a spread from the light emitting diode, and the second lens is a collimator lens. The light irradiation apparatus according to claim 1, wherein the light irradiation apparatus is a plate-shaped Fresnel lens that collects the shaped light from the light and makes the light incident on the light guide.   The light irradiation apparatus according to claim 4, wherein the second lens includes a plurality of plate-shaped Fresnel lenses. The light irradiation apparatus according to claim 1, wherein the case main body includes a plurality of case bodies, and a plurality of lenses are positioned and held at end portions of the case bodies.

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