JP2010261839A - Light irradiating device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light irradiating device, having a simple structure reducing a region not having a light source section, when an observation hole is viewed from a workpiece and executing appropriately shadowless illumination, or the like. <P>SOLUTION: The device includes: the observation hole provided between the workpiece of a product, or the like, which is a light irradiation object and an external observation point, on an observation axis connecting them; a first light source section provided around the observation hole, for irradiating the workpiece with light; a half-mirror section provided obliquely with respect to the observation axis on a position facing to the observation hole on the external observation point side; a second light source section provided at a position where the light emitted therefrom is reflected by the half-mirror section and irradiated to the workpiece through the observation hole; and a transparent member for covering the observation hole. The inner surface of the workpiece side of the transparent member is set so as to be a light-reflecting surface that reflects it toward the second light source section, the light transmitted through the transparent member, reflected by the half-mirror section, and advanced toward the inner surface, in the reflected light from the workpiece. <P>COPYRIGHT: (C)2011,JPO&INPIT

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 described in Patent Document 1 is known. This type of shadowless illumination device is used when a product or the like is illuminated with no shadow for the purpose of surface inspection or the like. An example of such a light irradiation device using a surface light emitting device is 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 FIG. 11, when the half mirror 103 is viewed from below the second light source unit 102 through the observation hole 101 a in the peripheral part of the workpiece W, the second light source unit 102 is not reflected and the workpiece W side is not reflected. It can be seen that there is a region where an image is shown.

  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 FIG.

  This is because the luminance of the second light source unit 102 is more uneven when viewed from below the second light source unit 102 in the peripheral portion of the workpiece W than when viewed from the center of the workpiece W. Means it looks like 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.

  The present invention has been made in view of such problems, and has a simple configuration, but reduces an area without a light source portion when viewing an observation hole from a work, and more suitably performs shadowless illumination or the like. It is a main intended problem to provide a light irradiation device capable of performing the above.

  That is, the light irradiation apparatus according to the present invention includes an observation hole provided on an observation axis between a workpiece such as a product to be irradiated with light and an external observation point and connecting them, and around the observation hole. A first light source unit that emits light to the workpiece, a half mirror unit that is provided at an angle with respect to the observation axis at a position facing the observation hole on the external observation point side, and emitted A second light source part provided at a position where light is reflected by the half mirror part and irradiated to the work through the observation hole, and a transparent member covering the observation hole, and the work in the transparent member A light reflecting surface on which the inner surface of the light is reflected by the half mirror part of the reflected light from the workpiece, reflected by the half mirror part, and reflected toward the second light source part. It is characterized by being.

  In such a case, a part of the light from the second light source part is reflected on the work side of the transparent member to change the traveling direction, so that the light from the second light source part is changed to the first of the peripheral parts of the work. It can guide well below the two light source sections. For this reason, without providing a new third light source part or adopting a complicated structure, it is possible to reduce the area without the light source part when viewing the observation hole from the work, and less uneven brightness. An illumination mechanism can be constructed.

  Another cause of uneven brightness is that the second light source part (the mirror image reflected on the half mirror) does not completely cover the observation hole, and a gap is formed around it. That is, when considering a direct optical system equivalent to the case where a half mirror is interposed, as shown in FIGS. 13 and 14, the virtual second light source unit 102 ′ has an actual second light source with the half mirror 103 as the axis of symmetry. It exists in the position symmetrical with the part 102. FIG.

  Therefore, when the observation hole 101a is viewed from the peripheral edge of the workpiece W, it can be seen that a region H1 where no light source portion exists is generated as shown in FIG. On the other hand, when viewing the observation hole 101a from the center of the workpiece W, the observation hole 101a is completely covered by the second light source unit 102 (virtual second light source unit 102 ′) as shown by the hatched area H2 in FIG. Looks.

  For this reason, light is irradiated from the whole sky direction of the observation hole 101a in the central part of the work W located on the observation axis C, whereas light is emitted from the whole sky direction of the observation hole 101a in the peripheral part of the work W. It is not irradiated, and the phenomenon that the periphery of the workpiece W is darker than the central portion of the workpiece W occurs. This is another cause of dark uneven portions on a part of the surface of the workpiece W.

  In order to reduce the unevenness and illuminate the work surface with uniform brightness, the optical path from the second light source unit to the half mirror and the optical path from the half mirror to the observation hole It is preferable that at least a part of the inner surface of the optical path is a light reflecting surface. Note that the second light source unit may be covered with a diffusion plate or the like, and a light extraction surface of the diffusion plate or the like may constitute the inner surface of the optical path. Further, the inner surface of the optical path may not be visible from the work side.

  In such a case, the same effect as when the area of the second light source unit is increased by the light reflecting surface can be obtained. Therefore, the observation hole can be viewed from the workpiece without increasing the size of the second light source unit. In this case, it is possible to further reduce the area without the light source portion, and to construct an illumination mechanism with less luminance unevenness.

  Further, if the transparent member is a rectangular solid solid body including the half mirror part, air is not interposed between the half mirror part and the transparent member, so that the light extraction efficiency is excellent. Can be configured.

  Further, if at least a part of the inner surface of the solid transparent body excluding the inner surface on the workpiece side is configured to function as the inner surface of the optical path, the inner surface is emitted from the second light source unit. Since the reflected light is totally reflected, it is not necessary to perform a specular treatment on the surface.

  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 optical path explanatory drawing explaining the optical path 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.

  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 and transparent plate having a square shape in plan view with a uniform thickness, 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 holds the cube beam splitter 7, the second light source unit 8 that emits light from the side end surface 7 a of the cube beam splitter 7, the cube beam splitter 7, and the second light source unit 8. And a frame body 9.

  The cube-type beam splitter 7 is a cuboid solid transparent body including a half mirror. Specifically, two rectangular prisms are bonded together, and a dielectric multilayer film, a metal thin film, or the like is bonded to the joint surface 71 thereof. It has been coated. The cube-type beam splitter 7 used in the present embodiment is transparent on the entire surface, and light can be totally reflected on the inner surface.

  The cube-type beam splitter 7 is mounted on the transparent plate 31 so as to cover the observation hole 311 provided in the transparent plate 31, and its joint surface 71 is an observation axis C between the observation hole 311 and the imaging device M. Above, it is arranged so as to be at an angle of 45 degrees with respect to the observation axis C.

  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 the side end surface 7a of the splitter 7 may be faced, and it irradiates light toward the joint surface 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 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 beam splitter 7, and is entirely reflected on the inner surface of the cube beam splitter 7 toward the bonding surface 71. Progress while reflecting. Then, the light reaching the joining surface 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 transmitted from the inner surface of the side end surface 7a of the cube-type beam splitter 7 to the inner surface A2 of the top optical path from the top side to the top side of the joint surface 71 and the bottom surface 7b. The light travels while being totally reflected on the inner surface A1 (not shown) of the opposite side optical path from the respective sides of the bottom optical path inner surface A1 and the side end surface 7a to the respective sides of the joint surface 71. Then, it is emitted from the bottom surface 7 b as uniformed diffused light, passes through the observation hole 311, 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, among the reflected light from the workpiece W, the light that passes through the bottom surface 7 b of the cube beam splitter 7, is reflected by the joint surface 71, and travels toward the inner surface of the bottom surface 7 b. Since the light is totally reflected and travels toward the second light source unit 8, when the joint surface 71 is viewed through the observation hole 311 from below the second light source unit 8 in the peripheral portion of the work W, the second light source unit 8 is viewed in the entire field of view. 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 unit.

  In the light irradiation device 1 according to such an embodiment, by using the cube beam splitter 7, a part of the light from the second light source unit 8 is reflected by the inner surface of the bottom surface 7 b of the cube beam splitter 7. Therefore, the light from the second light source unit 8 can be guided well below the second light source unit 8 in the peripheral portion of the work W. For this reason, the unevenness of the brightness of the surface of the workpiece W can be reduced.

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

  In addition, since the cube-type beam splitter 7 totally reflects on the inner surface, it is not necessary to perform a mirror surface treatment on the surface separately, and the configuration is very simple.

  Furthermore, since the observation hole 311 is provided in the transparent plate 31, the imaging device M can capture the light reflected by the work W and capture the light that has passed through the observation hole 311. Since the light reflected by the facing surface is not captured by the imaging device, moire does not occur on the imaging screen.

  The present invention is not limited to the above embodiment.

  For example, as illustrated in FIG. 5, the second light irradiation unit 6 includes a housing 11, a half mirror 71 attached to the housing 11, a transparent plate 7 covering the observation hole 31, a second light source unit 8, and a diffusion. The plate 10 may be used.

  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 7 is formed between the observation hole 311 and the imaging device M. On the observation axis C in the meantime, 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 7, 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 7. Then, the light emitted from the other surface 10 b is reflected by the half mirror 7, passes through the observation hole 311, and is irradiated onto the work W.

  The transparent plate 7 is a disc having a uniform thickness provided so as to close the observation hole 31.

  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 7 and the optical path from the half mirror 7 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 7, the bottom optical path wall inner surface A1 from the bottom of the other surface 10b to the observation hole 311, the other Opposing side optical path wall inner surface A3 (not shown) from each side of the surface 10b to each side of the half mirror 7 and bottom optical path wall inner surface from the bottom of the half mirror 7 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 the present embodiment, as shown in FIG. 6, among the reflected light from the workpiece W, the light that passes through the bottom surface 7 b of the transparent plate 7, is reflected by the bonding surface 71, and travels toward the inner surface of the bottom surface 7 b. The second light source unit 8 is reflected in the second light source unit 8 and viewed from the lower side of the second light source unit 8 through the observation hole 311 in the peripheral portion of the work W. 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 unit.

  Furthermore, as shown in FIG. 7, the observation hole 311 may have a truncated cone shape or a truncated pyramid shape that expands toward the anti-work facing surface 31 b in the transparent plate 31. 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, so that the side peripheral surface of the observation hole 311 looks dark and this also appears on the surface of the workpiece W. If the side peripheral surface of the observation hole 311 is a taper surface facing upward, the light emitted from the second light source unit 8 from the direction in which the conventional side peripheral surface is located can be a cause of uneven brightness. Irradiation can reduce the above-described unevenness in brightness. Further, in the embodiment shown in FIG. 1, even if the side peripheral surface of the observation hole 311 is subjected to a mirror treatment such as aluminum vapor deposition, the light passing through the observation hole 311 is totally reflected, so that the same effect can be expected. . Furthermore, although not shown, even if at least a part or the entire inner surface of the optical path from the observation hole 311 to the second light source unit 8 has a truncated cone shape or truncated pyramid shape that tapers in the light traveling direction. Good.

  Moreover, the 1st light irradiation part 2 may be dome shape illumination as shown in FIG. 8, and may be ring type illumination as shown in FIG.

  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 a mirror treatment by aluminum vapor deposition or the like.

  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, transparent plate (transparent member)
71 ... Joint surface (half mirror part)
7b ... Bottom (surface on the workpiece side)
8 ... 2nd light source part

Claims (4)

An observation hole provided on an observation axis between a workpiece such as a product to be irradiated with light and an external observation point and 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 unit and irradiated to the workpiece through the observation hole;
A transparent member covering the observation hole,
The inner surface on the workpiece side of the transparent member transmits light that has passed through the transparent member, reflected by the half mirror portion, and directed toward the inner surface from the reflected light from the workpiece toward the second light source portion. A light irradiation device, which is a light reflecting surface for reflection. An optical path inner surface covering an optical path from the second light source part to the half mirror part and an optical path from the half mirror part to the observation hole;
The light irradiation apparatus according to claim 1, wherein at least a part of the inner surface of the optical path is a light reflecting surface.   The light irradiation apparatus according to claim 1, wherein the transparent member is a rectangular solid solid transparent body including the half mirror portion.   The light irradiation apparatus according to claim 3, wherein at least a part of an inner surface of the solid transparent body excluding an inner surface on the workpiece side is the inner surface of the optical path.