JP5556733B2 - Light irradiation device - Google Patents

Description

  The present invention relates to a light irradiation apparatus that is suitably used for product surface inspection, mark detection, and the like.

  As a light irradiation device capable of coaxial illumination, for example, a shadowless illumination device as disclosed in Patent Document 1 is known. This type of shadowless illumination device is used when illuminating a product or the like with no shadow for the purpose of surface inspection or the like. As such a light irradiation device using a surface light emitting device, for example, the one shown in FIG.

  That is, the light irradiation apparatus 100 includes a planar light emitting surface (first light source unit) 101 disposed so as to cover a workpiece W such as a product, and visually recognizes the workpiece W from the outside at a central portion thereof. An observation hole 101a is provided. A coaxial illumination mechanism is provided in order to irradiate the work W with light also from the observation hole 101a. In this coaxial illumination mechanism, the half mirror 103 is arranged at an inclination of 45 ° almost directly above the observation hole 101a, and a planar light emitting surface (second light source unit) 102 is arranged on the side of the half mirror 103. The light emitted from the second light source unit 102 is reflected by the half mirror 103, passes through the observation hole 101a, and is irradiated onto the workpiece W.

JP 2001-215115 A

  When the half mirror 103 is provided like the light irradiation apparatus 100 and the light reflected by the half mirror 103 is irradiated on the surface of the work W, and the light reflected by the surface of the work W is captured and imaged, the work W A dark uneven portion may be formed on a part of the surface, and the uneven portion becomes a problem in precise surface inspection or the like.

  One of the factors that cause this uneven portion is that an image on the workpiece W side is reflected on the half mirror 103. That is, as shown in FIGS. 10 and 12, when the half mirror 103 is viewed from the peripheral portion of the workpiece W through the observation hole 101 a, an area in which an image on the workpiece W side is reflected without the second light source unit 102 being reflected is generated. You can see that

  On the other hand, when the half mirror 103 is viewed from the center of the workpiece W through the observation hole 101a, it can be seen that the second light source 102 is reflected in the entire field of view as shown in FIGS.

  This means that the brightness of the second light source 102 appears to be more uneven when viewed from the peripheral edge of the work W than when viewed from the center of the work W. This is one reason why dark uneven portions are generated on a part of the surface of the workpiece W when the surface of the workpiece W is captured in the bright field by capturing the regular reflection light. This is because when the surface of the work W is observed in a bright field, the brightness of the surface of the work W is determined by the luminance of the light source. This is because the unevenness in luminance is observed as the shade of the surface of the workpiece W as it is. This shading is the most problematic when observing in a bright field a work W having a high reflectivity with irregularities on the surface.

  In order to solve this problem, a third light source unit may be further installed on the workpiece W side. However, if this is done, the apparatus will be enlarged, and the loss of light quantity will increase and the efficiency will deteriorate.

  Further, since the light emitted from the light emitter 104 and traveling through the transparent plate 105 is totally reflected by the inner surface of the side peripheral surface of the observation hole 101a, the side peripheral surface of the observation hole 101a looks dark and this also appears on the surface of the workpiece W. This can cause uneven brightness.

  The present invention has been made in view of such a problem, and has a simple configuration, but effectively suppresses unevenness of the brightness of the work surface and can perform lightless illumination and the like more suitably. Providing a device is the main intended task.

  That is, the light irradiation apparatus according to the present invention includes an observation hole provided between a workpiece such as a product to be irradiated with light and an external observation point and on an observation axis connecting them, and the observation hole. A first light source unit that irradiates the workpiece with light, a half mirror that is provided obliquely with respect to the observation axis at a position facing the observation hole on the external observation point side, and emission And a second light source part provided at a position where the light reflected by the half mirror is irradiated onto the workpiece through the observation hole, and a transparent member fitted into the observation hole. It is characterized by that.

  If it is such, the said transparent member functions as a member for reflection, for example, totally reflects the light from a 2nd light source part in the inner surface of the side peripheral surface, or the inner surface of a workpiece | work opposing surface, and 2nd The light from the light source part can be guided well to the peripheral part of the workpiece. For this reason, it is possible to irradiate the entire workpiece surface with light with a simple configuration and to construct an illumination mechanism with less luminance unevenness.

  Examples of the half mirror include a mode in which the half mirror is included in a beam splitter made of a solid transparent body.

  In the case where the half mirror is contained in a beam splitter made of a solid transparent body, in order to guide the light from the second light source part well below the second light source part in the peripheral part of the work, the beam As the solid transparent body constituting the splitter, it is preferable to use one having an absolute refractive index larger than that of the transparent member. If it is such, the light from a 2nd light source part can be totally reflected by the inner surface of the lower end surface of a beam splitter, and the advancing direction can be changed.

  The first light source unit includes a flat transparent body in which the observation hole is formed, and a plurality of light emitters that introduce light into the transparent body, and emits light from a surface of the transparent plate facing the workpiece. In the case of the surface light emitting device to be led out, it is preferable that an end surface of the transparent member facing the workpiece is flush with a surface of the transparent body facing the workpiece. If it is such, there will be no discontinuous part in the derivation | leading-out surface of the light from a 1st light source part, and the derivation | leading-out surface of the light from a 2nd light source part, and light can be irradiated to the whole workpiece | work surface uniformly. .

  When the first light source unit is a surface light emitting device as described above, the light emitted from the plurality of light emitters and traveling through the transparent plate is totally reflected on the inner surface of the side peripheral surface of the observation hole. The side peripheral surface of the hole looks dark, which also causes uneven brightness on the workpiece surface. However, if the inner surface of the side peripheral end surface of the transparent member is a light reflecting surface, such a phenomenon that the side peripheral surface of the observation hole looks dark can be prevented. Further, if the outer surface of the side peripheral end surface of the transparent member is a light reflecting surface, light leakage from the side peripheral surface of the observation hole can be more reliably prevented, so that the workpiece facing surface of the transparent plate is observed. It can be set as the light derivation surface which derives light with uniform brightness up to the end on the hole side. And it is more preferable that both the inner surface and the outer surface of the side peripheral end surface of the transparent member are light reflecting surfaces.

  In order to totally reflect the light from the second light source unit on the inner surface of the side surface of the transparent member, it is preferable that the absolute refractive index of the transparent member is larger than the absolute refractive index of the flat transparent body. Alternatively, a surface of the transparent member facing the side peripheral surface of the observation hole may be covered with a material having an absolute refractive index smaller than that of the material constituting the transparent member, and the observation hole and the transparent member A gap may be formed between them.

  The transparent member may be integrated with the beam splitter and constitute an end portion on the side facing the workpiece.

  According to the present invention having such a configuration, it is possible to effectively reduce the area without the light source portion when the observation hole is viewed from the workpiece with a simple configuration.

It is a center longitudinal cross-sectional view of the light irradiation apparatus which concerns on one Embodiment of this invention. It is a top view of the light irradiation apparatus in the embodiment. It is a fragmentary longitudinal cross-sectional view of the optical member in the embodiment. It is an optical path explanatory drawing explaining the optical path of the light irradiation apparatus concerning the embodiment. It is a center longitudinal cross-sectional view of the light irradiation apparatus which concerns on other embodiment. It is a center longitudinal cross-sectional view of the light irradiation apparatus which concerns on other embodiment. It is a center longitudinal cross-sectional view of the light irradiation apparatus which concerns on other embodiment. It is a center longitudinal cross-sectional view of the light irradiation apparatus which concerns on other embodiment. It is a typical structure figure showing the conventional light irradiation device. It is an optical path explanatory drawing explaining the optical path of the conventional light irradiation apparatus. It is an optical path explanatory drawing explaining the optical path of the conventional light irradiation apparatus. It is an optical path explanatory drawing explaining the optical path of the conventional light irradiation apparatus. It is an optical path explanatory drawing explaining the optical path of the conventional light irradiation apparatus.

  An embodiment of the present invention will be described below with reference to the drawings.

  The light irradiation apparatus 1 according to the present embodiment is for use in, for example, irradiating light on an object (workpiece) such as a product in a factory or the like and automatically inspecting scratches or marks on the surface thereof. As shown in FIG. 1 and FIG. 2, the first light irradiation unit 2 and the second light irradiation unit 6 are provided.

Each part is described in detail below.
The first light irradiation unit 2 includes a rectangular plate-shaped optical member 3, a first light source unit 5 that emits light from the periphery of the optical member 3, and a frame that holds the optical member 3 and the first light source unit 5. And a body 4.

  The optical member 3 has one surface as a workpiece facing surface 31a and is arranged on a transparent plate 31 installed toward the workpiece W that is a light irradiation target, and the other surface (anti-work facing surface) 31b of the transparent plate 31. It is composed of a large number of reflection portions 32 provided.

  The transparent plate 31 is a colorless transparent body having an equal thickness and a square shape in plan view, and an observation hole 311 is formed on an observation axis C connecting the imaging device M and the workpiece W. For example, acrylic or glass is used. Etc.

  Each of the reflecting portions 32 has, for example, a circular shape in plan view, and is extremely small and thin with a diameter of several tens to several hundreds μm and a thickness of the order of microns. And as shown in FIG. 3, the said reflection part 32 is covered over the substantially whole surface except the side peripheral part of the anti-work opposing surface 31b in the transparent plate 31 so that the fine clearance S may be formed between each other. A large number of them are arranged in the vertical and horizontal directions at an equal pitch (for example, about 0.4 mm pitch). The reflecting portion 32 is formed from, for example, a white pigment containing a particulate reflecting filler that is a light diffusing member. The reflecting portion 32 mainly reflects light on the light reflecting surface, which is the surface of the reflecting portion 32, and enters the inside. A part of the light is diffused and reflected by the reflection filler.

  As shown in FIG. 2, the first light source unit 5 includes four units respectively corresponding to the four side peripheral end surfaces 31 c of the transparent plate 31. Each unit is composed of a single wiring board 52 in the form of a strip and a plurality of LEDs 51 mounted on the wiring board 52 in a line at equal intervals, and these LEDs 51 are arranged so as to face the side peripheral end face 31c of the transparent plate 31, Light is irradiated from the side peripheral end face 31 c toward the inside of the transparent plate 31.

  The frame body 4 has a square ring shape, and is made of metal having a circumferential groove that opens to the inner circumferential surface, for example, and holds and accommodates the first light source unit 5 in the circumferential groove. Further, the side peripheral edge of the transparent plate 31 is sandwiched from the thickness direction and held by the opening edge of the groove.

  The second light irradiation unit 6 irradiates light from a cube beam splitter 7, a transparent member 7 ′ provided continuously at the lower end of the cube beam splitter 7, and a side end surface 7 a of the cube beam splitter 7. The light source unit 8 includes a cube-type beam splitter 7 and a frame 9 that holds the second light source unit 8.

  The cube-type beam splitter 7 is a rectangular parallelepiped solid transparent body in which a half mirror 71 is included, the entire surface is transparent, and light can be totally reflected on the inner surface thereof. Specifically, the cube-type beam splitter 7 used in this embodiment forms a half mirror 71 by bonding two rectangular prisms and applying a coating made of a dielectric multilayer film or a metal thin film to the joint surface. It will be. The cube-type beam splitter 7 is disposed on the observation axis C between the observation hole 311 and the imaging device M so that the half mirror (joint surface) 71 is inclined at an angle of 45 degrees with respect to the observation axis C. ing.

  A separate rectangular parallelepiped transparent member 7 'is continuously provided at the lower end of the cube beam splitter 7, and there is no gap between the lower end surface 7d of the cube beam splitter 7 and the upper end surface of the transparent member 7'. Close. Specifically, the transparent member 7 ′ is made of a rod lens, and the rod lens is made of a material having an absolute refractive index smaller than that of the prism constituting the cube-type beam splitter 7. The transparent member 7 ′ is inserted into the observation hole 311 so as to close the observation hole 311 provided in the transparent plate 31, and a gap is formed between the side peripheral surface of the observation hole 311 and the side peripheral end surface 7 c of the transparent member 7 ′. Not close. Further, the transparent member 7 ′ is arranged so that the lower end surface 7 b and the work facing surface 31 a of the transparent plate 31 form a continuous surface.

  As a material of the rod lens constituting the transparent member 7 ′, a material having an absolute refractive index larger than that of the material constituting the transparent plate 31 is used. This is to ensure total reflection on the inner surfaces of the four side peripheral end faces 7c of the transparent member 7 '. Further, each of the four side peripheral end surfaces 7c of the transparent member 7 'is subjected to mirror treatment by aluminum vapor deposition or the like, and an outward light reflecting surface is configured.

  The second light source unit 8 includes a rectangular substrate 81 and a plurality (a large number) of LEDs 82 arranged on the substrate 81. The substrate 81 is installed in parallel with the observation axis C, and the LED 82 is a cube beam. It arrange | positions so that it may face the side end surface 7a of the splitter 7, and inject | emits light toward the half mirror 71 from the said side end surface 7a.

  The frame body 9 has a rectangular shape in a side view, and is made of a metal having, for example, a recess opening in a side end surface, and holds the second light source unit 8 in a groove formed on the inner surface of the recess. The side edge of the cube-type beam splitter 7 is sandwiched and held by the opening edge of the recess.

  Next, the operation of the light irradiation device 1 configured as described above will be described below.

  First, as shown in FIG. 1, the workpiece W and the imaging device M are installed facing each other, and the light irradiation device 1 is placed on the observation axis C so that the workpiece facing surface 31 a faces the workpiece W therebetween. Install in.

  In this state, when light is emitted from the second light source unit 8, the light enters the inside from the side end surface 7 a of the cube-type beam splitter 7, and is entirely incident on the inner surface of the cube-type beam splitter 7 toward the half mirror 71. Progress while reflecting. The light reaching the half mirror 71 is reflected there and travels toward the observation hole 311 while being totally reflected by the inner surface of the cube beam splitter 7.

  Specifically, the light emitted from the second light source unit 8 is totally reflected on the inner surfaces of the opposing side portions from each side of the side end surface 7 a of the cube beam splitter 7 to each side of the half mirror 71. While proceeding. Then, it exits from the lower end surface 7b as uniformed diffused light and is irradiated toward the workpiece W.

  On the other hand, the light emitted from the first light source unit 5 enters the inside from the side peripheral end surface 31c of the transparent plate 31, and, as shown in FIG. 3, faces the inner surface of the workpiece facing surface 31a and the opposite workpiece toward the center portion. It proceeds while being totally reflected between the inner surface of the surface 31b. In that process, the light that has reached the reflecting portion 32 attached to the anti-work facing surface 31b is diffusely reflected there, exits from the work facing surface 31a as uniformed diffused light, and is irradiated toward the work W. .

  The imaging device M captures the light reflected by the work W and passed through the observation hole 311 to pick up an image of the work W, and performs surface inspection and symbol reading of the work W.

  At this time, as shown in FIG. 4, the reflected light from the workpiece W passes through the lower end surface 7 b of the transparent member 7 ′ and is reflected by the half mirror 71 toward the inner surface of the lower end surface 7 d of the cube beam splitter 7. Since the reflected light L1 is totally reflected by the inner surface and travels toward the second light source unit 8, the second light source unit 8 is reflected in the entire field of view when the half mirror 71 is viewed from the peripheral edge of the work W through the observation hole 311. I can see it. For this reason, when the observation hole 311 is viewed from the workpiece W, it is possible to reduce the area without the light source part.

  Of the reflected light from the workpiece W, the light that has passed through the lower end surface 7b of the transparent member 7 ′, then totally reflected by the inner surface of the side peripheral end surface 7c of the transparent member 7 ′, and further toward the half mirror 71 Since L2 is reflected by the half mirror 71 and travels toward the second light source unit 8, when the side peripheral surface of the observation hole 311 is viewed from the peripheral part of the workpiece W, it can be seen that the second light source unit 8 is reflected. . For this reason, unevenness in brightness on the surface of the workpiece W can be reduced.

  In the light irradiation device 1 according to such an embodiment, a part of the light from the second light source unit 8 is entirely on the inner surface of the lower end surface 7d of the cube-type beam splitter 7 and the side peripheral end surface 7c of the transparent member 7 ′. Since the direction of travel is changed by reflection, the light from the second light source unit 8 can be guided well to the peripheral portion of the workpiece W. For this reason, the unevenness of the brightness of the surface of the workpiece W can be reduced.

  Further, in the optical path from the second light source unit 8 to the half mirror 71 and the optical path from the half mirror 71 to the observation hole 311, the light emitted from the second light source unit 8 is totally reflected on the inner surface of the cube-type beam splitter 7. The peripheral edge of W is also irradiated with light from all directions of the observation hole 311, so that the unevenness of brightness occurring at the peripheral edge of the work W can be greatly reduced, and more uniform light can be emitted over the entire surface of the work W. It becomes possible to irradiate.

  Further, in the conventional light irradiation device, the light emitted from the first light source unit 5 and traveling through the transparent plate 31 is totally reflected by the inner surface of the side peripheral surface of the observation hole 311, and therefore the light on the side peripheral surface of the observation hole 311. Although the outer surface looks dark and this also causes unevenness of brightness on the surface of the workpiece W, according to the present embodiment, of the light emitted from the second light source unit 8, the side peripheral end surface 7 c of the transparent member 7 ′. Since the light totally reflected from the inner surface is irradiated on the surface of the work W also from the direction of the side peripheral surface of the observation hole 311, the above-described brightness unevenness can be reduced.

  Further, since the outer peripheral surface 7c of the transparent member 7 ′ that is in close contact with the side peripheral surface of the observation hole 311 is subjected to an external mirror surface treatment, light leakage from the side peripheral surface of the observation hole 311 is further reduced. As a result, the workpiece facing surface 31a of the transparent plate 31 can illuminate the workpiece W with uniform brightness up to the end on the observation hole 311 side.

  The present invention is not limited to the above embodiment.

  For example, as shown in FIG. 5, the lower end portion 72 of the cube-type beam splitter 7 is extended, and the extended lower end portion 72 is inserted into the observation hole 311 provided in the transparent plate 31. Also good.

  Moreover, in order to ensure total reflection in the inner surface of the side peripheral end face 7c of the transparent member 7 ′, instead of using a material having a higher absolute refractive index than the material constituting the transparent plate 31 as the material of the transparent member 7 ′, a transparent member 7 'side peripheral end surface 7c may be covered with a material having an absolute refractive index smaller than that of the transparent member 7'. Then, in order to prevent the leakage of light from the surface of the transparent member 7 ′ together with ensuring the total reflection, the inward mirror surface treatment such as aluminum deposition is performed on the side peripheral end surface 7 c of the transparent member 7 ′. May be.

  Furthermore, as another measure for ensuring total reflection on the inner surface of the side peripheral end surface 7c of the transparent member 7 ', a gap is provided between the transparent member 7' and the observation hole 311 without bringing them into close contact with each other. Can be mentioned. In this way, total reflection on the inner surface of the side peripheral end face 7c of the transparent member 7 'can be ensured also by interposing air between the transparent member 7' and the observation hole 311.

  Further, in order to prevent light leakage from the surface of the cube-type beam splitter 7 more reliably, the surface may be subjected to an inward mirror surface treatment by aluminum vapor deposition or the like.

  Furthermore, the first light irradiation unit 2 may be a dome-type illumination as shown in FIG. 6, or may be a ring-type illumination as shown in FIG.

  As shown in FIG. 8, the second light irradiation unit 6 includes a housing 11, a half mirror 71 attached to the housing 11, a transparent member 7 ′ fitted in the observation hole 311, and a second light source unit. 8 and the diffusion plate 10 may be used.

  Here, the housing 11 has a rectangular shape in a plan view attached to the transparent plate 31 so as to cover the observation hole 311 provided in the transparent plate 31, and the half mirror 71 includes the observation hole 311 and the imaging device. On the observation axis C with respect to M, it is arranged at an angle of 45 degrees with respect to the observation axis C.

  The diffusion plate 10 is a rectangular thin plate interposed between the second light source unit 8 and the half mirror 71, and is disposed in parallel with the light emitting surface of the second light source unit 8. This diffusing plate 10 is like a cloudy glass having translucency and light diffusibility, and makes the light from the second light source unit 8 incident from one surface 10a more uniform, and half from the other surface 10b. The light is emitted toward the mirror 71. Then, the light emitted from the other surface 10 b is reflected by the half mirror 71, passes through the observation hole 311, and is irradiated onto the work W.

  In this embodiment, among the inner surface of the housing 11, the optical path wall inner surfaces A1, A2, A3, which cover the optical path from the second light source unit 8 to the half mirror 71 and the optical path from the half mirror 71 to the observation hole 311, A4 is a mirror surface.

  Specifically, the top optical path wall inner surface A2 from the top of the other surface 10b to the top of the half mirror 71, the bottom optical path wall inner surface A1 from the bottom of the other surface 10b to the observation hole 311, the other The opposite side optical path wall inner surface A3 (not shown) from each side of the surface 10b to each side of the half mirror 71 and the bottom optical path wall inner surface from the bottom of the half mirror 71 to the observation hole 311 A4 is subjected to electrolytic polishing or the like to obtain a mirror surface with very good surface accuracy.

  All of the optical path wall inner surfaces A1, A2, A3, and A4 may not be mirror surfaces, and any one or more of them may be mirror surfaces.

  In addition, the present invention is not limited to the above-described embodiments, and may be configured by appropriately combining some or all of the various configurations described above without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Light irradiation apparatus 311 ... Observation hole 5 ... 1st light source part 7 ... Cube-type beam splitter 72 ... Lower end part 71 ... Half mirror 7b ... Lower end surface 7 ' ..Transparent member 8 ... second light source C ... observation axis W ... work

Claims (8)

An observation hole provided between a workpiece such as a product to be irradiated with light and an external observation point, and on an observation axis connecting them;
A first light source provided around the observation hole and irradiating the work with light;
A half mirror provided obliquely with respect to the observation axis at a position facing the observation hole on the external observation point side;
A second light source unit provided at a position where the emitted light is reflected by the half mirror and irradiated to the workpiece through the observation hole;
And a transparent member fitted over the entire depth direction of the observation hole.   The light irradiation apparatus according to claim 1, wherein the half mirror is included in a beam splitter made of a solid transparent body.   The light irradiation apparatus according to claim 2, wherein an absolute refractive index of a solid transparent body constituting the beam splitter is larger than an absolute refractive index of the transparent member. The first light source unit further includes a flat transparent body in which the observation hole is formed, and a plurality of light emitters for introducing light into the transparent body, and emits light from a surface of the transparent body facing the workpiece. The light irradiation apparatus according to claim 1, 2 or 3 to be derived.   The light irradiation device according to claim 4, wherein an inner surface of a side peripheral end surface of the transparent member is a light reflecting surface.   The light irradiation apparatus according to claim 4 or 5, wherein an outer surface of a side peripheral end surface of the transparent member is a light reflecting surface.   The light irradiation apparatus according to claim 4, wherein an absolute refractive index of the transparent member is larger than an absolute refractive index of the flat transparent body.   The light irradiation apparatus according to claim 2, 3, 4, or 5, wherein the transparent member constitutes an end portion of the beam splitter that faces the workpiece.