JP2007078581A - Illumination device for visual inspection - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination device capable of performing visual inspection of high precision. <P>SOLUTION: The illumination device 20 for visual inspection is equipped with a light emitting diode group 68 for a dark visual field and a light emitting diode group 70 for a bright visual field. Upon visual examination due to the dark visual field method, only the light emitting diode group 68 for the dark visual field is made effective and, upon visual examination due to the bright visual field method, only the light emitting diode group 70 for the bright visual field is made effective. The illumination light emitted from the light emitting diode group 68 or 70 is diffused by a diffusion plate 74 or 78 to irradiate a contact lens 50 being an inspection target. Accordingly, the contact lens 50 is illuminated with uniform brightness and the so-called luminous intensity irregularity is not generated. As a result, visual examination can be performed with uniform precision over the whole of the contact lens 50. Upon visual examination due to the dark visual field method, the diffusion plate 78 for the dark visual field method is covered with a shutter plate 80 from above. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection illumination device, and more particularly to a visual inspection illumination device that irradiates, for example, an object to be inspected by a visual inspection device.

  This type of illumination device is used in, for example, an appearance inspection device for contact lenses. As such an appearance inspection apparatus for contact lenses, there is a conventional one disclosed in Patent Document 1, for example. According to this prior art, the circular light source means as an illuminating device is disposed below a contact lens that is an inspection object (inspection object). And circular illumination light is emitted from this circular light source means, and this illumination light is projected on a contact lens. Here, when the contact lens has a defect such as a flaw, the illumination light projected on the contact lens is irregularly reflected by the defective portion. Then, the irregularly reflected light is incident on an electronic imaging device disposed above the contact lens. As a result, a captured image in which the defective portion is emphasized is obtained, and the appearance inspection determination of the contact lens is performed based on the captured image. Note that mask means for shielding unnecessary illumination light passing through the outer periphery of the contact lens is provided between the contact lens and the electronic imaging device.

Japanese Patent Laid-Open No. 11-23414

  However, in the above-described conventional technology, the illumination light emitted from the circular light source means is directly projected onto the contact lens, so that uneven illuminance (distribution) occurs on the contact lens. For this reason, a place where the above-described defective portion is easily visible on the contact lens and a place where the above-described defective portion is not visible are generated, and there is a possibility that the defective portion may be overlooked depending on the case.

  Accordingly, an object of the present invention is to provide an illumination device for appearance inspection that can perform an appearance inspection with higher accuracy than before.

  In order to achieve such an object, the present invention provides a light emitting means for emitting light toward an inspection object in the visual inspection illumination apparatus for irradiating the inspection object by the visual inspection apparatus with light for illumination, and the light emitting means. And a light diffusing means provided between the inspection object and the object to be inspected and having a substantially semi-transparent property with respect to the light.

  That is, in this invention, light for illumination, that is, illumination light is emitted from the light emitting means, and this illumination light is applied to the inspection object via the light diffusing means. Here, the light diffusing means has a substantially semi-transparent property with respect to the illumination light, in other words, has an effect of scattering the illumination light. Therefore, the illumination light is diffused by the scattering action by the light diffusing means, and the diffused illumination light is irradiated to the inspection object. As a result, the inspection object is illuminated with uniform brightness, and uneven illuminance is suppressed.

  There may be a plurality of light emitting means. In this way, the illumination range (area) by the illumination light is expanded, and the intensity of the illumination light (illuminance of the inspection object) is improved.

  In this case, a light diffusing unit is provided between all the light emitting units and the inspection object. It is desirable that the distance from each light emitting means to the inspection object is substantially equal, and the distance from each light emitting means to the light diffusing means is also substantially equal. In this way, the illumination conditions of the illumination light from each light emitting means to the inspection object through the light diffusing means become substantially equal, and even when a plurality of light emitting means are provided, the occurrence of uneven illuminance is suppressed. .

  Such an invention is applied to, for example, a so-called dark field appearance inspection apparatus that performs an appearance inspection by irradiating an inspection object with illumination light from an oblique direction and observing scattering and reflection of the illumination light. The In this case, the inspection object is arranged on the optical axis of the objective lens included in the appearance inspection apparatus. Then, the light emitting means is displaced from the arrangement position of the inspection object in the direction along the optical axis, and at a position farther from the optical axis than the periphery of the inspection object in the direction perpendicular to the optical axis. Provided.

  The appearance inspection by the dark field method is suitable for, for example, inspecting the outline (edge) of the inspection object and the surface state of the inspection object, particularly the presence or absence of defects such as wrinkles on the surface. .

  Further, in the appearance inspection application by the dark field method, for example, when the inspection object is a transparent body having a property of being substantially transparent to the illumination light, the light emitting means is arranged in a direction along the optical axis of the objective lens. You may provide in the position away from the said objective lens rather than the said test object. According to this configuration, in the direction along the optical axis of the objective lens, the illumination light is irradiated to the inspection object from the side opposite to the objective lens with the inspection object interposed therebetween.

  Further, a prevention means for preventing the illumination light from directly entering the objective lens may be provided. That is, the prevention means is provided to prevent the illumination light emitted from the light emitting means or the illumination light transmitted through the light diffusion means from directly entering the objective lens. By providing such a prevention means, it is possible to eliminate direct light that becomes an obstacle in appearance inspection by the dark field method (in other words, when observing scattering and reflection of illumination light), and an optical image with high contrast can be obtained. Obtainable.

  Further, depending on the form of the inspection object, the illumination light applied to the inspection object may be extremely refracted and the refracted light may enter the objective lens. In addition, illumination light may be irregularly reflected between the inspection object and the container for holding it, and the irregularly reflected light may enter the objective lens. In this way, when refracted light or irregularly reflected light is incident on the objective lens, the optical image of the light emitting means by these refracted light or irregularly reflected light is superimposed on the optical image of the inspection object, that is, it is reflected. Occurs. This reflection phenomenon may hinder the appearance inspection work. Therefore, in order to avoid such a reflection phenomenon, a changing means for changing the distance between the inspection object and the light emitting means in the direction along the optical axis of the objective lens may be provided. That is, when the distance is changed by the changing means, the irradiation angle of the illumination light to the inspection object changes. When the illumination light irradiation angle changes in this way, the traveling direction of the above-described refracted light or irregularly reflected light changes, thereby avoiding the reflection phenomenon.

  The present invention also irradiates the inspection object with illumination light straightly, and performs an appearance inspection by observing transmitted light that has passed through the inspection object out of the illumination light. Can also be applied. In this case, the inspection object is disposed on the optical axis of the objective lens of the appearance inspection apparatus. The light emitting means is provided at a position facing the objective lens with the inspection object interposed therebetween.

  The appearance inspection by the bright field method is suitable for, for example, inspecting the internal state of a substantially transparent inspection object, in particular, the presence or absence of defects such as bubbles and foreign matter.

  In addition, in this visual field inspection application by the bright field method, changing means for changing the direction of illumination light applied to the inspection object via the light diffusion means between the inspection object and the light diffusion means, Further, it may be provided. The changing means referred to here is to change the direction of the illumination light by diffractive action or refracting action. As such changing means, for example, a specific pattern is drawn with opaque ink on a transparent sheet. And those having specific irregularities formed on the surface of a transparent sheet. That is, when the changing means is interposed between the light diffusing means and the inspection object, the direction of the illumination light applied to the inspection object is changed to an oblique direction. Then, by illuminating the inspection object with the illumination light from the oblique direction, the outline of the inspection object and the surface on the surface of the inspection object are the same as in the appearance inspection by the dark field method described above. It becomes possible to recognize the presence or absence of such defects. Moreover, it becomes easier to recognize the presence or absence of defects such as bubbles in the inspection object.

  The illuminating device applied to such a bright field method can be accommodated in one housing together with the illuminating device applied to the dark field method described above. In this case, an enabling means for enabling any one of the lighting devices is provided. In this way, it is possible to cope with both the appearance inspection by the dark field method and the appearance inspection by the bright field method. That is, an illumination device for both the dark field method and the bright field method can be realized.

  An example of the inspection object in the present invention is a contact lens.

  According to the present invention, the inspection object can be illuminated with uniform brightness, that is, uneven illuminance does not occur. Therefore, the appearance inspection can be performed with higher accuracy than the above-described conventional technique in which the appearance inspection accuracy is lowered due to the influence of the illuminance unevenness.

  1st Embodiment at the time of applying this invention to the external appearance inspection apparatus 10 for contact lenses is described with reference to FIGS.

  As shown in FIG. 1, an appearance inspection apparatus 10 according to the first embodiment includes a base part 12 as a base part, a head part 14 provided above the base part 12, and the base part 12. And a connecting portion 16 that connects the head portion 14 to each other.

  The base portion 12 has a substantially rectangular parallelepiped shape, and includes a personal computer (strictly the main body of the personal computer) 18 as an image processing device and a power supply device 22 for a light source unit 20 described later. Is arranged. A sample stage unit 26 is provided on the upper surface 24 of the base 12.

  The sample stage unit 26 includes a rectangular plate-shaped base 28 fixed to the upper surface 24 of the base portion 12, a Z-axis stage 30 fixed at an appropriate position on the base 28, and an L-shape on the Z-axis stage 30. And a light source unit 20 as an illuminating device fixed through a fixture 32 having a shape. As will be described in detail later, a generally bowl-shaped transparent container 34 is placed at a predetermined position on the light source unit 20, and a contact lens 50 as an inspection object is accommodated in the container 34. In other words, it is set.

  The sample stage unit 26 is configured so that the center O (see FIG. 2) of the container 34 is positioned on an optical axis 38 of a CCD (Charge Coupled Device) camera 36 described below. When the Z-axis stage 30 is operated, the light source unit 20 moves along with the container 34 in the direction along the optical axis 38. As a result, the focus of the CCD camera 36 is adjusted. The operation of the Z-axis stage 30 can be directly performed manually or indirectly by using the personal computer 18 (command input means such as a keyboard or a mouse (not shown)). Further, the image processing by the personal computer 18 can be used to automatically operate the Z-axis stage 30, that is, to perform automatic focus adjustment.

  The CCD camera 36 includes a single-focus type magnifying objective lens 40 that has the optical axis 38 and the CCD camera 36, and the incident surface of the magnifying objective lens 40 faces downward, that is, faces the container 34. The head portion 14 is provided. A video output terminal (not shown) of the CCD camera 36 is connected to a video input terminal (not shown) of the personal computer 18. The magnifying objective lens 40 can be arbitrarily replaced with one having a different magnification. For example, the magnification can be arbitrarily changed within a range of 5 to 100 times. Instead of the CCD camera 36, other types of cameras such as a CMOS (Complimentary Metal Oxide Semiconductor) type may be used.

  Further, a liquid crystal display 42 as a display means is provided in the head unit 14 with the display screen exposed to the front side of the head unit 14. A video input terminal (not shown) of the display 42 is connected to a video output terminal (not shown) of the personal computer 18. Instead of the liquid crystal display 42, other types of displays such as a CRT (Cathode Ray Tube) type may be employed.

  According to the appearance inspection apparatus 10 configured in this manner, when the illumination light is irradiated from the light source unit 20 to the contact lens 50 set in the container 34, the optical image of the contact lens 50 is enlarged. The light enters the CCD camera 36 through the lens 40. The CCD camera 36 converts the incident optical image into a video signal that is an electrical signal, and the converted video signal is input to the display 42 via the personal computer 18. As a result, an enlarged image of the contact lens 50 is displayed on the display screen of the display 42. Then, from this enlarged image, the appearance of the contact lens 50 is inspected, and for example, the shape and size, or the presence or absence of defects such as wrinkles and bubbles, etc. are inspected. The appearance inspection (good / bad determination) can also be automatically performed by image processing by the personal computer 18.

  By the way, the single appearance inspection apparatus 10 according to the first embodiment can perform both the appearance inspection by the dark field method and the appearance inspection by the bright field method. This is realized by the light source unit 20 functioning as an illumination device for both the dark field method and the bright field method. For this reason, the light source unit 20 is configured as follows.

  That is, as shown in FIG. 2, the light source unit 20 has a substantially rectangular parallelepiped casing 60. In the state where the light source unit 20 is fixed to the Z-axis stage 30 via the fixture 32 as described above, the upper surface portion 62 and the bottom surface portion 64 of the housing 60 are horizontal, and the above-described enlargement. It is orthogonal to the optical axis 38 of the objective lens 40 (CCD camera 36). Furthermore, a circular through hole 66 centering on the optical axis 38 is formed in the upper surface portion 62. Then, the container 34 is placed so as to close the through hole 66 from above.

  The container 34 is substantially bowl-shaped as described above. Specifically, the container 34 has a substantially spherical crown-shaped bottom portion 34a protruding downward, and a short cylindrical shape that extends straight upward from the periphery of the bottom portion 34a. Wall portion 34b. The container 34 is integrally formed of a material transparent to illumination light from the light source unit 20, for example, transparent glass such as soda glass or quartz glass, or transparent resin such as polycarbonate or ABS resin. The container 34 is supported by the peripheral edge of the through hole 66 in a state where the outer surface of the bottom portion 34 a is in contact with the peripheral edge of the through hole 66.

  In order to form such a support state of the container 34 by the through hole 66, the diameter φa of the container 34 is larger than the diameter φb of the through hole 66. For example, the diameter φb of the through hole 66 is 30 [mm] to 60. In contrast to [mm], the diameter of the container 34 is 50 [mm] to 80 [mm]. The center O of the bottom 34a of the container 34 is also the apex of the bottom 34a, and the container 34 is placed so that the center O of the bottom 34a is positioned on the optical axis 38 of the magnifying objective lens 40. .

  Then, a colorless and transparent liquid 52 is injected into the container 34, and the contact lens 50 is placed in a state where the front surface (projected side surface) is directed downward into the container 34 into which the liquid 52 has been injected. It is thrown in quietly. Then, the contact lens 50 sinks slowly (flickering) downward, that is, toward the bottom 34 a of the container 34. When the contact lens 50 reaches (contacts) the inner surface of the bottom 34a, the contact lens 50 naturally moves toward the vertex of the inner surface, that is, the center O according to gravity. As a result, the contact lens 50 settles at a fixed position with respect to the center O, that is, is set on the optical axis 38.

  The liquid 52 is a so-called drying preventing agent for preventing the contact lens 50 from drying (especially shrinkage in the case of a soft type). The liquid 52 also functions as a buffering agent for reducing the mechanical impact on the contact lens 50. As the liquid 52, for example, a generally known contact lens storage solution is suitable, but a liquid other than the storage solution may be employed as long as it is harmless to the contact lens 50 and the human body.

  The liquid 52 is injected to such an extent that the contact lens 50 is sufficiently immersed, but a wall 34 b is provided to prevent the liquid 52 from flowing out of the container 34. That is, the wall 34b functions as a so-called liquid outflow prevention means for preventing the liquid 52 from flowing out. The height dimension Ha of the wall 34b is sufficient if it is at least several [mm] or more, for example, about 10 [mm] to 20 [mm].

  The thickness dimension ta of the container 34 is substantially constant in both the bottom 34a and the wall 34b, and is, for example, about 1 [mm] to 3 [mm]. Further, the curvature radius R of the inner surface of the bottom 34a is also substantially constant. The curvature radius R of the inner surface is desirably larger than the curvature radius (front curve) of the front surface of the contact lens 50 in contact with the inner surface, and is, for example, about 100 [mm] to 300 [mm].

  The contact lens 50 may be either a soft type or a hard type. In any case, the diameter φc of the contact lens 50 is smaller than the diameter φb of the through hole 66 described above. For example, in the case of a soft type, the diameter is about 13.8 [mm] to 14.5 [mm]. In the case of a hard type, it is about 8.4 [mm] to 9.4 [mm].

  Inside the housing 60, a so-called dark-field light emitting diode (LED) group 68 that is used for visual inspection by the dark field method, and a so-called bright-field light emitting diode group 70 that is used for visual inspection by the bright field method. Are provided. Among these, the dark-field light-emitting diode group 68 has a large number (several tens to hundreds) of white light-emitting diodes 72, 72,. These light emitting diodes 72, 72,... Are provided in an annular shape so as to surround the optical axis 38 around the optical axis 38 of the magnifying objective lens 40 in the vicinity of the upper surface portion 62 in the housing 60. . Further, the light emitting diodes 72, 72,... Have a plurality of stages in the vertical direction (the direction along the optical axis 38), for example, a three-stage configuration. The light emitting portions (bullet-like portions) of the respective light emitting diodes 72, 72,... Are directed to the vicinity of the center of the through hole 66. In other words, the contact lens 50 located near the center of the through hole 66 is connected to the contact lens 50. Is directed. Further, the distance from the light emitting portion of each light emitting diode 72, 72,... To the vicinity of the center of the through hole 66 is substantially constant. Therefore, the light emitting diodes 72, 72,... Arranged below are closer to the optical axis 38 than the light emitting diodes 72, 72,. However, the distance from the optical axis 38 to each of the light emitting diodes 72, 72,... Is larger than the distance (φb / 2) from the optical axis 38 to the periphery of the through hole 66. In other words, in the horizontal direction (direction perpendicular to the optical axis 38), each of the light emitting diodes 72, 72,... Is located farther from the optical axis 38 than the peripheral edge (edge portion) of the contact lens 50.

  .. Are arranged between the light emitting diodes 72, 72,... (Light emitting diode group 68), specifically between the light emitting diodes 72, 72,. A dark field diffusion plate 74 is provided. The dark field diffusion plate 74 is formed of a material that is translucent to light emitted from the light emitting diodes 72, 72,..., So-called illumination light for dark field, for example, heat such as polypropylene or acrylic. A plastic resin that has been matted. The distance from the inner side surface of the dark field diffusion plate 74 to the vicinity of the center of the through hole 66 (for example, the center of the front surface of the contact lens 50) is substantially uniform over the entire inner side surface. The distance from the outer surface of the diffusing plate 74 to the light emitting portions of the light emitting diodes 72, 72,... Is also substantially uniform over the entire outer surface. Further, the thickness tb of the dark field diffusion plate 74 is uniform over the entire dark field diffusion plate 74, for example, about 0.5 [mm] to 3 [mm]. The upper end (large opening side) of the dark field diffusion plate 74 is in close contact with the upper surface 62 of the housing 60, and the lower end (small opening side) is the light emitting diode 72 located at the lowest position. , 72,... Are further opened below.

  On the other hand, the bright-field light-emitting diode group 70 also has many (several dozen) white light-emitting diodes 76, 76,... Of the same standard as the light-emitting diodes 72, 72,. ing. These light emitting diodes 76, 76,... Are in the vicinity of the bottom surface portion 64 of the housing 60, just below the through hole 66, in other words, at positions facing the magnifying objective lens 40 through the through hole 66. It is provided so as to have a plane (two-dimensional) density so as to have a spread that is approximately the same size as the through-hole 66. The light emitting portions of these light emitting diodes 76, 76,... Are directed right above, that is, directed to the through hole 66.

  Further, between each of the light emitting diodes 76, 76,... (Light emitting diode group 70), specifically between the light emitting diodes 76, 76,. A disc-shaped bright field diffusion plate 78 is provided horizontally. The bright-field diffuser plate 78 is also formed of a translucent material similar to the above-described dark-field diffuser plate 74, and the thickness tc thereof is uniform over the entire bright-field diffuser plate 78. For example, it is about 0.5 [mm] to 3 [mm]. Therefore, the distance in the vertical direction from the upper surface of the bright field diffusion plate 78 to the through-hole 66 is uniform over the entire upper surface, and the light emitting diodes 76, 76,... From the lower surface of the bright field diffusion plate 78. The distance to the light emitting portion is uniform over the entire lower surface. The diameter φd of the bright field diffusion plate 78 is larger than the diameter φb of the through hole 66, and is, for example, 50 [mm] to 80 [mm].

  Further, a disc-shaped shutter plate 80 as a light shielding means is provided above the bright-field diffuser plate 78, more specifically between the bright-field diffuser plate 78 and the lower end of the dark-field diffuser plate 74. It is provided horizontally. The shutter plate 80 is formed of a material opaque to the illumination light for bright field emitted from the light emitting diodes 76, 76,..., For example, a metal such as aluminum or stainless steel, or a resin such as acrylic or ABS. It is made of. Further, the surface of the shutter plate 80 is coated with a matte black paint exhibiting a high absorption rate for the bright field illumination light (and dark field illumination light). The shutter plate 80 is connected to a shutter operation knob 82 provided on the outside of the housing 60, for example, on the upper surface portion 62. By operating the shutter operation knob 82, a bright field diffusion plate is obtained. It can be arbitrarily excluded from above 78. Specifically, when the shutter operation knob 82 is operated (rotated) in the direction indicated by the arrow 84 in FIG. 2A, the shutter plate 80 moves to the position indicated by the two-dot chain line 80a in FIG. However, it is excluded from above the bright field diffusion plate 78. The diameter φe of the shutter plate 80 is larger than the diameter φd of the bright-field diffusion plate 78, more specifically, larger than the opening diameter at the lower end of the dark-field diffusion plate 74, for example, 60 [mm] to 100 It is about [mm].

  According to the light source unit 20 configured as described above, only the dark field light emitting diode group 68 is validated and the bright field light emitting diode group 70 is invalidated by the above-described power supply device 22 during the visual field inspection by the dark field method. It becomes. That is, only the dark-field light emitting diodes 72, 72,... Emit light, and the bright-field light emitting diodes 76, 76,. As a result, as shown by dotted arrows 90, 90,... In FIG. 3, dark field illumination light is emitted from the dark field light emitting diodes 72, 72,. The contact lens 50 is irradiated through the diffusion plate 74 and the container 34 (bottom 34a). That is, the dark field illumination light is applied to the contact lens 50 obliquely from below.

  Here, the dark field diffusion plate 74 is formed of a material that is translucent to the dark field illumination light as described above, and in other words, has an effect of scattering the dark field illumination light. Therefore, the dark field illumination light emitted from each of the light emitting diodes 72, 72,... Is diffused by the scattering action by the dark field diffusion plate 74, and the diffused light is irradiated to the contact lens 50. Therefore, unlike the above-described conventional technique in which the illumination light emitted from the circular light source means is directly projected onto the contact lens, the entire contact lens 50 can be irradiated with uniform (blurred) brightness, and the contact Irradiance unevenness does not occur on the lens 50.

  Further, the propagation conditions of the dark-field illumination light from the dark-field light-emitting diodes 72, 72,... To the contact lens 50 in the container 34 through the dark-field diffusion plate 74, that is, the respective light-emitting diodes. The irradiation conditions of the dark field illumination light onto the contact lens 50 by 72, 72,... Are substantially equal. Accordingly, there is no illuminance unevenness due to the difference in the irradiation conditions.

  Now, it is assumed that there are defects such as wrinkles on the surface of the contact lens 50. In this case, the dark field illumination light applied to the contact lens 50 is irregularly reflected by the defective portion. Then, the irregularly reflected light is incident on the CCD camera 36 via the magnification objective lens 40. As a result, an image in which the defective portion is emphasized is displayed on the display screen of the display 42 described above. The dark field illumination light is also irregularly reflected by the edge portion of the contact lens 50. Accordingly, the edge portion is also displayed on the display screen of the display 42. On the other hand, when there is no defect in the contact lens 50, only the edge portion is projected, and the other portion is projected as a dark (so-called dark) image with the surface (upper surface) of the shutter plate 80 as the background.

  As described above, according to the appearance inspection by the dark field method, it is possible to effectively inspect the edge portion of the contact lens 50 and the presence or absence of defects on the surface of the contact lens 50.

  .. Are covered with the upper surface portion 62 of the housing 60. The light emitting diodes 72, 72,. In other words, the upper surface portion 62 of the housing 60 is interposed between the light emitting diodes 72, 72,... And the magnifying objective lens 40. Therefore, the dark field illumination light emitted from each of the light emitting diodes 72, 72,... Does not directly (linearly) enter the magnification objective lens 40. That is, the upper surface portion 62 of the housing 60 functions as a preventing means for preventing the dark field illumination light from directly entering the magnifying objective lens 40 from each of the light emitting diodes 72, 72,. In addition, by preventing direct incidence of light to the magnifying objective lens 40 in this way, an optical image having a high contrast can be obtained in an appearance inspection in the dark field direction.

  In addition, depending on the positional relationship between the dark field light emitting diodes 72, 72,... And the contact lens 50, the optical image of the light emitting diodes 72, 72,. A phenomenon occurs. This reflection phenomenon is caused by, for example, the dark field illumination light applied to the contact lens 50 as indicated by a dotted arrow 92 in FIG. 4 and the contact lens 50 as indicated by a two-dot chain arrow 94 in FIG. It is assumed that the light is diffusely reflected between the container 34 (bottom 34a) and the diffusely reflected light is incident on the magnifying objective lens 40. Although not shown in the figure, the reflection phenomenon also occurs when the dark field illumination light is refracted extremely greatly by the contact lens 50 or the container 34 and the refracted light is incident on the magnification objective lens 40. It is speculated that there is. If such a reflection phenomenon occurs, there is a risk of hindering the appearance inspection work.

  Therefore, in the first embodiment, the relative positional relationship between the dark-field light emitting diodes 72, 72,... And the contact lens 50 can be changed. Can be arbitrarily changed in the direction along the optical axis 38 of the magnifying objective lens 40. More specifically, for example, as shown in FIG. 5, the upper surface portion 62 of the casing 60 on which the container 34 is placed can be arbitrarily replaced with a through hole 66 having a different diameter φb. 5 shows a state in which the through hole 66 has a diameter φb larger than that of the upper surface portion 62 in FIG. 3, for example, and in this case, the position of the container 34 moves downward. On the contrary, when the upper surface portion 62 of the housing 60 is replaced with one having a through hole 66 having a small diameter φb, the position of the container 34 moves upward. For example, as shown in FIG. 6, the position of the container 34 can be moved by providing an annular spacer 100 between the container 34 (bottom 34 a) and the upper surface 62 of the housing 60. In this case, the position of the container 34 is adjusted by the height dimension Hb of the spacer 100.

  When the position of the container 34 moves in the direction along the optical axis 38 in this way, the irradiation angle of the dark field illumination light with respect to the contact lens 50 set in the container 34 changes. Then, by changing the irradiation angle of the dark field illumination light in this way, the traveling direction (angle) of the irregularly reflected light and the refracted light causing the above-described reflection phenomenon is changed, so that the reflection phenomenon is avoided. . This reflection phenomenon is avoided when each of the light emitting diodes 72, 72,... Is slightly below the contact lens 50 (center of the front surface), for example, several [mm], in the direction along the optical axis 38. The

  On the other hand, at the time of visual inspection by the bright field method, only the bright field light emitting diode group 70 is validated and the dark field light emitting diode group 68 is invalidated by the power supply device 22 described above. In other words, only the bright field light emitting diodes 76, 76,... Emit light, and the dark field light emitting diodes 72, 72,. In addition, the shutter plate 80 is removed from above the bright field diffusion plate 78 by the shutter operating knob 82 described above, as shown in FIG. As a result, bright field illumination light is emitted from the light field light emitting diodes 76, 76,..., As indicated by dotted arrows 110, 110,. The contact lens 50 in the container 34 is irradiated through the diffusion plate 78 for use. That is, bright field illumination light is irradiated onto the contact lens 50 from directly below.

  Here, the bright field illumination light is diffused by the bright field diffusion plate 78 when passing through the bright field diffusion plate 78. Then, the diffused light is applied to the contact lens 50. Therefore, the entire contact lens 50 can be irradiated with uniform brightness, and the above-described uneven illuminance does not occur. Further, the propagation conditions of the bright-field illumination light from the bright-field light emitting diodes 76, 76,... To the contact lens 50 in the container 12 through the bright-field diffusion plate 78, that is, the respective light-emitting diodes. The irradiation conditions of the bright field illumination light onto the contact lens 50 by 76, 76,... Are substantially equal. Therefore, uneven illuminance due to the difference in the irradiation conditions does not occur.

  The bright field illumination light irradiated from directly below the contact lens 50 in this way passes through the contact lens 50 and enters the magnifying objective lens 40. As a result, the image of the contact lens 50 based on the transmitted light is displayed on the display screen of the display 42 described above. When there is a defect such as a bubble in the contact lens 50, the bright field illumination light is scattered by the defective portion. Therefore, the defect portion is projected in a manner different from other (good) portions.

  However, since the contact lens 50 is extremely thin and exhibits a very high transmittance with respect to visible light including bright field illumination light, the defect portion such as the above-described bubbles is not displayed on the image displayed on the display 42. Although it can be recognized, it is not easy to recognize other parts such as the contour (edge) of the contact lens 50. Therefore, in the first embodiment, as shown in FIG. 8, a pattern sheet 120 as a changing unit is placed on the bright field diffusion plate 78. The pattern sheet 120 is for changing the propagation direction of the bright field illumination light applied to the contact lens 50 via the bright field diffuser plate 78. By using the pattern sheet 120, the contact is made. The outline of the lens 50 is easily recognized.

That is, as shown in FIG. 9, the pattern sheet 120 is formed on a transparent sheet (film) 122 such as an OHP (Over Head Projector) sheet or the like and a predetermined pattern 124 such as a lattice pattern with opaque ink such as black ink. Is drawn. For example, the pattern sheet 120 can be obtained by converting the predetermined pattern 124 into a CAD (Computer
Aided Design) or the like, and this can be created by printing on the transparent sheet 122.

  In a state where the pattern sheet 120 is placed on the bright field diffusion plate 78, a part of the bright field illumination light irradiated to the contact lens 50 through the bright field diffusion plate 78 is the pattern sheet. Diffracted by 120 (pattern 124 portion). As a result, as indicated by dotted arrows 112, 112,... In FIG. 8, the propagation direction of the part of the bright field illumination light is changed, and is directed, for example, in an oblique direction with respect to the optical axis 38. By irradiating the contact lens 50 with bright field illumination light propagating in the oblique direction, a state similar to that in the appearance inspection by the dark field method described above is formed, and the contour of the contact lens 50 is recognized. It becomes easy to do. The contact lens 50 is also irradiated with bright-field illumination light that linearly passes through the pattern sheet 120 (portion other than the pattern 124), as indicated by dotted arrows 110, 110,. .

  FIG. 10 (reference FIG. 1) shows an example of an image displayed on the display screen of the display 42 when the pattern sheet 120 is used. In FIG. 10, the portion that appears as a dark grid pattern is an image of the pattern 124 drawn on the pattern sheet 120. A circular pattern that appears to protrude slightly from the entire range of the image is an image of the contour portion of the contact lens 50. As described above, the pattern sheet 120 is interposed between the contact lens 50 and the bright field diffusion plate 78, so that the outline portion of the contact lens 50 is easily recognized. A discontinuous portion called a blend exists inside the periphery of the contact lens 50. According to the figure, this blend can also be recognized (the contour image in the figure). A circular pattern that is smaller than the contour image that is visible inside is a blend image). Such a blend was difficult to recognize in the conventional visual field inspection by the bright field method, but by using the pattern sheet 120, the blend was successfully clarified. Although not shown in the drawing, when there is a defect such as a bubble in the contact lens 50, the defective part is also clearly displayed. At this time, the image of the pattern 124 becomes the background of the image of the contact lens 50. Then, there is a concern that the image of the pattern 124 as the background may overlap with, for example, an image of a defective portion in the contact lens 50, so that the defective portion becomes difficult to recognize. However, the above-described magnification objective lens 40 is focused on the contact lens 50, and the image of the pattern 124 is blurred.

  FIG. 10 shows a display on the display 40 when a pattern sheet 120 in which straight lines with a width of about 0.5 [mm] are drawn in a grid pattern at intervals of about 1.0 [mm] is used as the predetermined pattern 124. It is an example of the image to be performed. Further, in FIG. 11 (reference diagram 2), as the predetermined pattern 124, a pattern sheet 120 in which straight lines with a width of about 0.5 [mm] are drawn in a grid pattern at intervals of about 5.0 [mm] is used. An example of the display image is shown. Thus, since the appearance of the image differs depending on the form of the predetermined pattern 124, the predetermined pattern 124 may be selected in accordance with the form of the contact lens 50 that is the inspection object.

  The predetermined pattern 124 is not limited to a lattice shape, and may be a spot (dot) pattern as shown in FIG. 12, or a concentric pattern as shown in FIG. Also in this case, the size of the spots, the interval between the lines, and the like may be appropriately changed. Needless to say, other patterns, for example, a pattern in which a straight line is drawn on a radiation stripe, a pattern in which parallel lines are drawn, a pattern in which a curve is drawn, or the like may be employed. However, the pattern is preferably not a random shape but drawn according to a certain pattern. Further, instead of the pattern sheet 120, a simple net-like material (such as a so-called mandarin orange net) may be placed.

  Furthermore, as the pattern sheet 120, for example, as shown in FIG. 14, a plurality of strips (or long shapes) of transparent bodies 132, 132,... Having the same quality as the transparent sheet 130 are latticed on a transparent sheet 130. You may employ | adopt what formed the unevenness | corrugation on the said transparent sheet 130 by overlapping in the shape. In this case, the bright field illumination light applied to the contact lens 50 via the bright field diffusion plate 78 is not only diffracted but also refracted by the uneven portion. And the propagation direction of the bright field illumination light is changed by this diffraction action and refraction action, and as a result, the same effect as described above is obtained. An example of an image when the pattern sheet 120 shown in FIG. 14 is used is shown in FIG. 15 (reference FIG. 3). As can be seen from FIG. 15, when the pattern sheet 120 shown in FIG. 14 is used, the contour portion of the contact lens 50 is particularly clarified. In addition, the shape, arrangement | positioning, etc. of transparent body 132,132, ... are not restricted to the aspect shown in FIG. 14, The aspect other than this may be sufficient.

  When such a pattern sheet 120 is used, that is, when the contact lens 50 is inspected for outlines and blended parts, and further on the surface of the contact lens 50 by a visual field inspection by the bright field method, the bright field diffusion plate 78 is used. May be omitted. That is, by providing the pattern sheet 120 without providing the bright-field diffuser 78, the contour or blended portion of the contact lens 50, the wrinkles on the surface, etc. are clarified by the diffractive or refractive action of the pattern sheet 120. can do.

  As described above, according to the first embodiment, both the dark-field illumination light and the bright-field illumination light are not directly applied but are diffused by the diffusion plate 74 or 78 on the contact lens 50. Irradiated. Therefore, uneven illuminance does not occur on the contact lens 50, and the contact lens 50 is illuminated with uniform brightness. That is, the appearance inspection of the contact lens 50 can be performed with higher accuracy compared to the above-described conventional technique in which the appearance inspection accuracy is reduced due to the influence of uneven illuminance.

  Although the above-described dark field diffusion plate 74 is made of resin, it is not limited to this. For example, it may be made of translucent glass such as frosted glass or white glass, or may be made of translucent paper such as trace paper. The same applies to the bright field diffusion plate 78.

  The dark-field light-emitting diodes 72, 72,... And the bright-field light-emitting diodes 76, 76,. Further, instead of these light emitting diodes 72, 72,..., 76, 76,..., Other light emitting means such as a light bulb may be used. Further, the arrangement of the light emitting diodes 72, 72,... And 76, 76,... (The shape of each of the light emitting diode groups 68 and 70) is not limited to the content described in the first embodiment.

  Further, the dark field light emitting diodes 72, 72,... (Light emitting diode group 68) may be provided above the contact lens 50 in the direction along the optical axis 38 of the magnifying objective lens 40. In this case, it goes without saying that the dark field diffusion plate 68 is also provided above the contact lens 50.

  Furthermore, the container 34 is generally bowl-shaped, but is not limited thereto. That is, a container 34 having a shape other than this may be used, or a commercially available one such as a petri dish may be used.

  Moreover, although the contact lens 50 was mentioned as an example as a test target object, things other than this, for example, various industrial parts, medical instruments, etc., can also be used as the test target object.

  Then, 2nd Embodiment of this invention is described with reference to FIGS. In the second embodiment, a light source unit 200 as shown in FIG. 16 is employed instead of the light source unit 20 in the first embodiment described above.

  That is, as shown in FIG. 16, the light source unit 200 according to the second embodiment floats the light-field light emitting diode group 70 from the bottom surface portion 64 of the housing 60 in the light source unit 20 according to the first embodiment. The shutter plate 80 is removed from the configuration.

  More specifically, a substantially disc-shaped movable plate 202 is provided immediately below the through hole 66. The movable plate 202 is horizontally provided in a state of floating from the bottom surface portion 64 of the housing 60. A bright-field light emitting diode group 70 is provided on the movable plate 202, and more specifically, the light emitting diode group. The light-emitting diodes 76, 76,... Constituting the 70 are densely arranged in a plane in a state where the respective light-emitting portions are directed right above. A bright-field diffuser plate 78 is horizontally provided above the light-emitting diodes 76,. The bright field diffusion plate 78 is fixed to the upper surface of the movable plate 202 via a cylindrical support 204, for example. The movable plate 202, the light emitting diode group 70, the bright field diffusion plate 78, and the support 204 constitute a bright field illumination unit 206.

  The bright field illumination unit 206 is connected to an illumination operation knob 208 outside the housing 60. The bright field illumination unit 206 can be arbitrarily removed from directly below the through hole 66 by operating the proof operation knob 208. Specifically, when the illumination operation knob 208 is operated (rotated) in the direction indicated by the arrow 210 in FIG. 16A, the bright field illumination unit 206 moves to the position indicated by the two-dot chain line 206a in FIG. However, it is excluded from directly below the through hole 66.

  Further, a circular black body sheet 212 is attached to at least a portion of the bottom surface portion 64 in the housing 60 that is positioned directly below the through hole 66. This black body sheet 212 exhibits a high absorptance with respect to dark field illumination light, similar to the matte black paint described above. The diameter φf of the black body sheet 212 is larger than the diameter φb of the through hole 66, and is, for example, about 60 [mm] to 100 [mm].

  According to the light source unit 200 configured as described above, only the dark field light emitting diode group 68 is enabled and the bright field light emitting diode group 70 is disabled by the above-described power supply device 22 at the time of visual inspection by the dark field method. It becomes. That is, only the dark-field light emitting diodes 72, 72,... Emit light, and the bright-field light emitting diodes 76, 76,. At the same time, the illumination operation knob 208 eliminates the bright field proof unit 206 including the bright field light emitting diode group 68 from directly below the through-hole 66 as shown in FIG. As a result, bright field illumination light is emitted from the light field light emitting diodes 76, 76,... As indicated by dotted arrows 220, 220,. The contact lens 50 in the container 34 is irradiated through the diffusion plate 78 for use. In this state, an appearance inspection is performed by the dark field method.

  In the appearance inspection by the dark field method, the black body sheet 212 is the background of the contact lens 50. Here, in the first embodiment described above, considering that the upper surface of the shutter plate 80 is the background, the distance Hc from the background to the contact lens 50 is that of the second embodiment as compared to the first embodiment. Is bigger. In general, the larger the distance Hc is, the closer the background is to an ideal black body, which is advantageous for visual inspection by the dark field method. That is, according to the second embodiment, the appearance inspection by the dark field method can be performed better than in the first embodiment.

  On the other hand, at the time of visual inspection by the bright field method, the bright field light emitting diode group 68 is arranged directly below the through hole 66 by the illumination operation knob 208 as shown in FIG. Then, only the bright-field light-emitting diode group 70 is enabled and the dark-field light-emitting diode group 68 is disabled by the power supply device 22 described above. In other words, only the bright field light emitting diodes 76, 76,... Emit light, and the dark field light emitting diodes 72, 72,. As a result, bright field illumination light is emitted from the bright field light emitting diodes 76, 76,..., As indicated by dotted arrows 230, 230,. The contact lens 50 in the container 34 is irradiated through the diffusion plate 78 for use. In this state, an appearance inspection is performed by the bright field method.

  In the second embodiment, the above-described pattern sheet 120 may be placed on the bright field diffusion plate 78.

  Further, the black body sheet 212 may be attached to the entire bottom surface portion 64, or the above matte black paint may be applied instead of the black body sheet 212.

  As described above, the contents described in the first embodiment and the second embodiment are a part of examples for realizing the present invention, and do not limit the present invention.

It is a figure showing the whole visual inspection device composition concerning a 1st embodiment of this invention. It is a figure which shows schematic structure of the light source unit in the 1st Embodiment. It is an illustration figure which shows the state of the light source unit at the time of the external appearance inspection by a dark field method. It is an illustration figure for demonstrating a reflection phenomenon. It is an illustration figure which shows an example for avoiding the same reflection phenomenon. FIG. 6 is an illustrative view showing an avoidance example different from FIG. 5. It is an illustration figure which shows the state of the light source unit at the time of the external appearance test | inspection by a bright field method. It is an illustration figure which shows the state in which the pattern sheet is used in the external appearance inspection by the same bright field method. It is a figure which shows an example of the same pattern sheet. It is a figure which shows an example of the image obtained at the time of use of the pattern sheet of FIG. It is a figure which shows the image obtained at the time of use of the pattern sheet different from FIG. It is a figure which shows an example of the pattern sheet different from FIG. It is a figure which shows an example of the pattern sheet further different from FIG. It is a figure which shows an example of the pattern sheet further different from FIG. It is a figure which shows an example of the image obtained at the time of use of the pattern sheet of FIG. It is a figure which shows schematic structure of the light source unit in 2nd Embodiment of this invention. It is an illustration figure which shows the state of the light source unit at the time of the external appearance test | inspection by the dark field method in the 2nd Embodiment. It is an illustration figure which shows the state of the light source unit at the time of the external appearance test | inspection by a bright field method in the 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Appearance inspection apparatus 20 Light source unit 50 Contact lens 68 Dark-field light emitting diode group 70 Bright-field light-emitting diode group 72 Dark-field light-emitting diode 74 Dark-field diffuser plate 76 Bright-field light-emitting diode 78 Bright-field diffuser plate

Claims (10)

In the illumination device for appearance inspection that irradiates the inspection object with the light for illumination by the appearance inspection device,
A light emitting means for emitting the light toward the inspection object;
A light diffusing means provided between the light emitting means and the inspection object and having a substantially translucent property to the light;
An illumination device for visual inspection, comprising: A plurality of the light emitting means,
The light diffusing means is provided between each of the plurality of light emitting means and the inspection object,
The distance from the plurality of light emitting means to the inspection object is substantially equal,
The distances from the plurality of light emitting means to the light diffusing means are substantially equal.
The illumination device for visual inspection according to claim 1. The appearance inspection apparatus includes an objective lens on which an optical image of the inspection object is incident,
The inspection object is disposed on the optical axis of the objective lens,
The light emitting means is provided at a position away from the optical axis in the direction perpendicular to the optical axis and in the direction perpendicular to the optical axis in the direction along the optical axis. Be
The illumination device for visual inspection according to claim 1 or 2. The inspection object is a transparent body that is substantially transparent to the light,
The light emitting means is provided at a position farther from the objective lens than the inspection object in a direction along the optical axis.
The illumination device for visual inspection according to claim 3. A prevention means for preventing the light from directly entering the objective lens;
The illumination device for appearance inspection according to claim 3 or 4. A changing unit that changes a distance between the inspection object and the light emitting unit in a direction along the optical axis;
The illumination device for visual inspection according to any one of claims 3 to 5. The appearance inspection apparatus includes an objective lens on which an optical image of the inspection object is incident,
The inspection object is a transparent body that is substantially transparent to the light, and is disposed on the optical axis of the objective lens.
The light emitting means is provided at a position facing the objective lens across the inspection object.
The illumination device for visual inspection according to claim 1 or 2.   The external appearance according to claim 7, further comprising a changing unit that is provided between the inspection object and the light diffusing unit and changes a direction of the light irradiated to the inspection object through the light diffusing unit. Lighting device for inspection. The visual inspection illumination device according to any one of claims 3 to 6 and the visual inspection illumination device according to claim 7 or 8 are accommodated in one housing.
An activation means for activating any one of the illumination devices for visual inspection housed in the housing;
Lighting device for visual inspection.   The illumination device for appearance inspection according to claim 1, wherein the inspection object is a contact lens.