TWI747365B - Visual inspection device - Google Patents

Abstract

The present invention provides an appearance inspection device that can suppress the occurrence of halation and is excellent in inspection processing speed. The appearance inspection apparatus includes: a transport unit that transports the test object, a camera, a plurality of illuminators that photograph each partial imaging area of the surface of the test object transported by the transport unit, and irradiate illumination light toward the area Illuminator, one or more diffusers arranged in the irradiating direction of the illuminator, and an image processing unit that processes image data obtained by the camera, the one or more diffusers and the plurality of illuminators each The irradiation directions are vertical respectively.

Description

Visual inspection device

The present invention relates to an appearance inspection device.

In the production site, etc., visual inspection equipment is used to confirm the state of the solder on the circuit board and whether there are defects on the glass surface. As an appearance inspection device, for example, light is irradiated to the test object such as a substrate, the surface of the test object is captured with a camera to obtain an image, and the surface condition of the test object is judged by confirming the image. Such a device has been used by the public. Know.

When the reflectivity of the surface of the test object is high, etc., the image obtained by the camera will produce halo, which makes the appearance inspection difficult. As an inspection device for suppressing halation, Japanese Patent Laid-Open Publication No. 2001-208702 discloses a defect inspection device that includes a light source for irradiating inspection light at a predetermined angle to a predetermined area on the surface of the inspection target; The light receiving unit is arranged at a position deviated from the optical axis of the specular reflection light from the area; and the light shielding unit is arranged on a line segment connecting the virtual image of the light source and the light receiving unit and is located between the inspection target and Between the light receiving units, the light that is irradiated from the light source to the light receiving unit and causes halo is shielded.

According to the above defect inspection apparatus, since the light receiving unit does not receive the inspection light that is specularly reflected on the surface of the inspection object being transported, but only receives scattered and diffracted diffuse reflection light, it is possible to suppress the occurrence of halation. However, if the conveying speed of the inspection object is increased in order to increase the inspection processing speed, or the illuminance of the inspection light is increased for reasons such as inspecting the surface of the inspection object whose reflectivity is not constant, it may not be possible to suppress halos. The production of light.

In view of the above-mentioned problems, an object of the present invention is to provide an appearance inspection apparatus that is excellent in inspection processing speed while suppressing the occurrence of halation.

In order to solve the above-mentioned problems, the appearance inspection apparatus of the present invention includes: a conveying part that conveys the test object; a camera that photographs each partial imaging area of the surface of the test object conveyed by the conveying part; and multiple An illuminator that irradiates illuminating light toward the shooting area; one or more diffusers arranged in the illuminating direction of the illuminator; and an image processing unit that processes image data obtained by the camera, the one or The plurality of diffusers are perpendicular to the respective irradiation directions of the plurality of luminaires.

According to the above-mentioned visual inspection apparatus, the image processing unit processes the image to generate an image of the entire surface of the test object while acquiring the image data of the test object conveyed by the conveying unit, and performs the whole process. The image is judged whether there are abnormal parts, so the inspection processing speed is excellent, and the appearance inspection can be performed efficiently. Since the image data is obtained by imaging each partial imaging area of the surface of the object to be inspected by a camera, it is easier to increase the transport speed and increase the inspection processing speed compared to imaging the entire surface of the object at one time. Since the appearance inspection device has a plurality of illuminators, even if the conveying speed of the test object is increased, sufficient illuminance for the camera to obtain image data can be provided, and the inspection processing speed can be further increased. In addition, since the diffuser plate is perpendicular to the respective irradiation directions of the plurality of luminaires, the illuminating light can be efficiently diffused, halation can be suppressed, and highly accurate appearance inspection can be performed. In addition, "perpendicular" to the irradiation direction of the diffuser plate and the luminaire means that the normal direction of a part of the diffuser plate located in the irradiation direction of the luminaire coincides with the illuminating direction, where "the normal direction and the illuminator "The above-mentioned irradiation direction is the same" is not only the case of complete coincidence, but also includes the case where the above-mentioned normal direction and the above-mentioned irradiation direction are not completely coincident under the condition that the diffusion of the illumination halo light can be suppressed, for example, also includes relative to the above-mentioned normal direction. , The above-mentioned irradiation direction has an inclination within 5°.

In the visual inspection apparatus, it is also possible to arrange a diffuser for each of the plurality of luminaires, and it is preferable that the one diffuser and the respective irradiation directions of the plurality of luminaires are perpendicular to each other. In this way, the illumination light of the plurality of luminaires can be uniformly diffused through the one diffuser plate, and compared with arranging the diffuser plates for the plurality of luminaires, the device can be downsized with a simple structure.

Preferably, the above-mentioned one diffuser plate is partially cylindrical, and the cross section of the diffuser plate is arc-shaped. In this way, it is possible to make the incident surface of the illuminating light in the one diffuser plate and the respective irradiating directions of the plurality of illuminators perpendicular to each other through a simple structure.

Preferably, the shooting direction of the camera is perpendicular to the shooting area, and the plurality of illuminators are symmetrically arranged with the shooting direction of the camera as a reference. In this way, the camera can accurately image the imaging area from a substantially top view in the vertical direction, and the imaging area can be accurately illuminated by the plurality of illuminators arranged symmetrically with the imaging direction of the camera as a reference. In addition, the shooting direction of the camera and the shooting area "perpendicular" means that the normal direction of the shooting area is consistent with the shooting direction. Here, "the normal direction and the shooting direction are consistent" are not only the case of complete coincidence. Under the condition that it is possible to shoot in a substantially top view, the normal direction and the shooting direction do not completely match, for example, the case where the shooting direction has an inclination within 5° with respect to the normal direction.

Preferably, the irradiation directions of each of the plurality of illuminators respectively cross the imaging area. In this way, uniform and sufficient illuminance can be easily obtained in the above-mentioned imaging area. In addition, "intersection" not only means that the respective illumination directions of the plurality of illuminators intersect the surface of the test object in the above-mentioned imaging area, but also include the case where they intersect near the surface under the condition that uniform and sufficient illuminance can be obtained. Depending on the inspection object, for example, it also includes the case where the intersection of the irradiation direction and the surface of the inspection object in the imaging area are separated by within 1 mm.

It is preferable that the conveyance speed of the said conveyance part is 70 mm/sec or more. In this way, the processing speed of the appearance inspection is improved, and the appearance inspection device with excellent processing ability can be obtained.

Preferably, the number of pixels of the above-mentioned camera is 8000 or more, and the resolution is 7.00 μm/pixel or less. In this way, it is possible to clearly image the surface of the test object whose conveying speed is relatively fast, so that accurate appearance inspection can be easily performed.

Preferably, it is 8 seconds or less from the acquisition of the image of the surface of the test object to the end of the processing and inspection of the entire area of the surface of the test object by the image processing unit. In this way, it can be an appearance inspection device excellent in inspection efficiency of appearance inspection.

The visual inspection device described above suppresses halation and has high inspection accuracy, and has an excellent inspection processing speed.

Hereinafter, an appearance inspection apparatus according to an embodiment of the present invention will be described in detail based on the drawings.

(Visual inspection device)

As shown in FIG. 1, the appearance inspection apparatus 1 of one embodiment of the present invention mainly includes: a conveying unit (not shown) for conveying the test object 2; Each partial shooting area of the illuminator; a plurality of illuminators 4 that irradiate the illumination light toward the above-mentioned area; one or more diffusers 5 arranged in the illuminating direction of the illuminator 4; and processing image data obtained by the camera 3 Image processing unit (not shown).

The test object 2 is not particularly limited. For example, a substrate on which a pattern of a plurality of wafers (electronic components) is formed, and paste in which pastes such as Ag (silver), Ru (ruthenium), or glass are screen-printed on the surface of the substrate can be mentioned. The agent coats a test object with a plate shape such as a substrate, a glass plate, a wafer, a metal plate, and the like, and the surface is a substantially flat surface. In addition, the "surface of the test object" is the surface of the test object on the side that is photographed by the camera, and the surface on the side that is not in contact with the conveying unit.

(Transportation Department)

The transport department transports the inspected object 2. In FIG. 1, the test object 2 is conveyed from left to right on the paper surface in the conveying direction X. The conveying method is not particularly limited, and a method of conveying by a belt conveyor, placing the test object 2 on a stage and conveying the stage with a linear motor or the like can be used.

The speed at which the transport unit transports the test object 2 is not particularly limited, and can be appropriately selected according to the characteristics of the test object 2 such as the transport method, size, and weight. As a lower limit of the said conveyance speed, it is 70 mm/sec, for example, Preferably it is 140 mm/sec, More preferably, it is 210 mm/sec. The upper limit of the conveying speed is not particularly limited, and it may be 500 mm/sec, for example. When the conveying speed is less than the above-mentioned lower limit, the processing capacity of the appearance inspection apparatus 1 may be reduced. On the other hand, when the transport speed exceeds the above upper limit, the camera 3 may not be able to clearly image the surface of the test object 2.

(camera)

The camera 3 photographs the surface of the test object 2 transported by the transport unit. The camera 3 continuously photographs a partial area on the surface of the test object 2. In other words, the camera 3 photographs each partial photographing area on the surface of the subject. The camera 3 includes imaging elements such as CCD (Charged Coupled Devices) and CMOS (Complementary Metal Oxide Semiconductor) that convert the incident light as an image into image data, and uses the converted image data as an electrical signal, which is connected with wiring The image processing unit described later sends it.

The camera 3 is not particularly limited, and an area sensor camera, a line sensor camera, etc. can be used, and it is preferable to use a line sensor camera capable of capturing images at high speed and high resolution. As the lower limit of the numerical value (number of pixels) of the above-mentioned imaging element, 8000 pixels are preferable, and 16000 pixels are more preferable. The upper limit of the number of pixels is not particularly limited, and may be 64,000 pixels, for example. When the above-mentioned number of pixels is less than the above-mentioned lower limit, the image on the surface of the test object 2 that is transported at a high speed may become unclear, making it difficult to accurately inspect. The upper limit of the resolution of the camera is preferably 7.00 μm/pixel, more preferably 5.00 μm/pixel, and most preferably 3.52 μm/pixel. The lower limit of the above-mentioned resolution is not particularly limited, and may be, for example, 1 μm/pixel. When the above-mentioned resolution exceeds the above-mentioned upper limit, the image of the surface of the test object 2 that is transported at a high speed may become unclear, making it difficult to accurately inspect.

As the arrangement of the camera 3, it is preferable that the photographing direction C of the camera 3 is perpendicular to the above-mentioned photographing area. Specifically, it is preferable that the camera 3 is arranged so as to be perpendicular to the imaging plane of the camera 3 and passing through the center of the imaging plane of the camera 3 (hereinafter, also referred to as the “central axis of the camera imaging plane”) perpendicular to the above-mentioned imaging area. With this arrangement, a plurality of illuminators 4 and diffuser plates 5, which will be described later, can be easily arranged. In addition, the “imaging surface of the camera 3” represents the surface on the side of the imaging element where the image (light) of the captured object 2 (subject) is incident on the imaging element.

The imaging surface of the camera 3 may include a lens for condensing the light in the imaging area to the imaging element.

(Illuminator)

The illuminator 4 irradiates illuminating light toward the above-mentioned photographing area photographed by the camera 3. Configure multiple luminaires4. Specifically, the illuminator 4 is arranged such that the irradiation directions P of the illumination light of the plurality of illuminators 4 respectively face the above-mentioned photographing area photographed by the camera 3.

It is preferable that the irradiation directions P of the illumination light of each of the plurality of illuminators 4 intersect in the above-mentioned imaging area on the surface of the test object 2, and it is more preferable that the irradiation direction P of each of the above-mentioned illuminating lights and the imaging direction C are in the above-mentioned imaging area. Cross in the area. In this way, sufficient illuminance is obtained for the above-mentioned shooting area, so that the camera 3 can easily obtain clear image data.

The illuminator 4 is not particularly limited, and may be an incandescent bulb, a fluorescent lamp, or the like provided with a reflecting plate for irradiating diffused light on the surface of the test object 2, and it is preferable to use LED (Light Emitting Diode) illumination. When a linear sensor camera is used as the camera 3, it is more preferable to use linear LED illumination in which semiconductor elements, namely, LED chips are arranged in a row.

In addition, it is preferable that the illuminator 4 can adjust the brightness from an image processing unit etc. which will be described later. In this way, it is possible to irradiate illumination light with an optimal brightness in accordance with the characteristics of the surface of the test object 2, the conveyance speed of the test object 2, and the like, so that the accuracy of the appearance inspection can be improved.

The arrangement position of the plurality of illuminators 4 is not particularly limited, and it may be arranged radially with the imaging direction C as the central axis. That is, when viewing the irradiation direction P of the illumination light of each of the plurality of illuminators 4 from the center of the above-mentioned imaging area, the plurality of illuminators 4 can be arranged such that the irradiation direction P is radial. The arrangement position of the plurality of illuminators 4 is preferably arranged in series from the downstream side to the upstream side in the transport direction X of the test object 2. That is, it is preferable that a plurality of illuminators 4 are arranged side by side in a direction parallel to the conveyance direction X of the test object 2 (refer to FIG. 1 ). In this way, the configuration of the plurality of luminaires 4 can be simplified, thereby making the appearance inspection apparatus 1 compact. Although the arrangement positions of the plurality of illuminators 4 may be arranged asymmetrically on the downstream side and the upstream side in the conveying direction with respect to the arrangement position of the camera 3, it is preferable to arrange the camera 3 with its imaging direction C perpendicular to the above-mentioned imaging area. The arrangement is such that the arrangement positions of the plurality of luminaires 4 are symmetrically arranged on the downstream side and the upstream side. That is, it is preferable that the plurality of illuminators 4 are symmetrically arranged with the imaging direction C of the aforementioned camera 3 as a reference. In this way, since uniform illumination light is irradiated from the downstream side and the upstream side in the above-mentioned area, the camera 3 can easily obtain clear image data.

The number of luminaires 4 is not particularly limited, and can be appropriately selected according to the arrangement space and the like. For example, in the case where the above-mentioned downstream side and the upstream side are symmetrically arranged, it may be two or four. That is, when the above-mentioned camera 3 is symmetrically arranged with reference to the shooting direction C, the number of the plurality of illuminators 4 can be set to two or four.

The arranging method of the luminaire 4 is not particularly limited, and it can be arranged through an installation support or the like. Preferably, it is arranged through a support or the like whose arrangement position and the irradiation direction of the luminaire 4 can be changed. By changing the arrangement position, irradiation direction, and the like of the illuminator 4, the illuminator 4 can be easily arranged corresponding to the resolution of the camera 3, the characteristics of the surface of the test object 2, and the like.

The color of the illuminating light of the illuminator 4 is not particularly limited, and may be white, red, blue, infrared, ultraviolet, or the like in accordance with the characteristics of the surface of the test object 2. When the test object 2 is a light-transmitting object such as glass, a red color with a long wavelength is preferable, and when it is an object with strong light reflectivity such as metal, a blue color with a short wavelength is preferable, and white is more preferable.

The lighting method of the luminaire 4 is not particularly limited, and it may be full-time lighting or stroboscopic lighting, and it is preferable to adopt full-time lighting. Through full-time light emission, stable image data can be obtained at relatively low brightness.

(Diffuser)

The diffuser plate 5 diffuses the above-mentioned illuminating light and suppresses regular reflection of the above-mentioned illuminating light. The diffusion plate 5 is arranged in the irradiation direction P of the plurality of luminaires 4. The diffusion plate 5 is perpendicular to the irradiation direction P of each luminaire 4, respectively. Specifically, the diffuser plate 5 is arranged between the plurality of illuminators 4 and the test object 2, so that the incident side surface (incident surface) of the illumination light of the plurality of illuminators 4 and the irradiation direction P of each illuminator 4 are respectively vertical. More specifically, when viewed from a side view perpendicular to the transport direction of the test object 2 and the imaging direction C (FIG. 2 ), the central axis of the respective beam of the illumination light is arranged perpendicular to the incident surface.

The diffusion plate 5 has a substantially rectangular shape in plan view, and the length W (FIG. 3) of the surface of the test object 2 perpendicular to the conveying direction X (the width direction of the test object 2) is preferably greater than the width of the test object 2.

Preferably, the irradiation directions P of one diffuser plate 5 and the plurality of luminaires 4 are perpendicular to each other. In other words, it is preferable that the diffuser plate 5 is a diffuser plate shared by a plurality of luminaires 4. Specifically, it is preferable not to arrange the plurality of diffuser plates 5 for the plurality of luminaires 4, but to arrange only one common diffuser plate 5 for the plurality of luminaires 4. Since the incident surface of one diffuser plate 5 is perpendicular to the respective irradiation directions P of the plurality of illuminators 4, it is preferable that the above-mentioned one diffuser plate 5 is partially cylindrical, and the cross section of the diffuser plate 5 is arc-shaped. The cross-sectional shape of the diffuser plate 5 in the aforementioned side view angle is preferably polygonal, semi-elliptical, circular arc, etc., among which circular arc is the best. By making the diffuser plate 5 into a partial cylindrical shape whose cross-sectional shape is an arc, the incident surface of the diffuser plate 5 and the irradiation direction P of each illuminator 4 can be easily made perpendicular to each other.

For example, as shown in FIG. 2, the camera 3 is arranged such that the imaging direction C is perpendicular to the surface of the test object 2, and two or four illuminators 4 are symmetrical to the camera 3 on the downstream and upstream sides of the transport direction of the test object 2. In the case of arrangement, by aligning the intersection between the irradiation directions P with the center point of the arc-shaped cross section of the diffuser plate 5, the incident surface of the diffuser plate 5 can be perpendicular to the irradiation direction of the plurality of illuminators 4.

In addition, the range of the above-mentioned arc, that is, the cross section of the diffuser 5, with respect to the center of the arc, the angle θ from one end of the diffuser 5 as a reference (0°) to the other end is not particularly limited. For example, Above 120° and below 180°.

One diffuser plate 5 is provided with a through hole 51 for allowing the camera 3 to photograph the above-mentioned shooting area. For example, as shown in FIG. 3, the through hole 51 is formed in a slit shape in the longitudinal direction of the diffuser plate 5.

The lower limit of the light transmittance of the diffuser plate 5 is not particularly limited, and can be appropriately selected according to the beam of the illuminating light and the like. For example, it can be set to 50%, preferably 60%, and more preferably 70% or more. The upper limit of the light transmittance of the diffusion plate 5 is not particularly limited, and it may be 90%, for example. The diffuse reflectance of the diffuser plate 5 is not particularly limited, and can be appropriately selected according to the beam of the illumination light, etc., and may be, for example, 90% or more and 95% or less.

The diffusion plate 5 may be a resin plate or the like containing light diffusion particles, or a film-like diffusion sheet may be attached to a transparent resin plate or a glass plate. The material of the resin plate to which the film-like diffusion sheet is added is not particularly limited as long as it has high transparency. For example, polycarbonate or the like can be used.

(Image Processing Department)

The image processing unit processes the image data acquired by the camera 3. Specifically, the image data of a partial area on the surface of the test object 2 continuously captured by the camera 3 is received, and the received multiple image data are processed to generate an overall image of the surface of the test object 2 , And determine whether there is an abnormal part in the overall image. Preferably, the image processing unit includes a display unit (display) for displaying the above-mentioned overall image and the determination result of the presence or absence of an abnormal part, and includes an operation unit of the appearance inspection device 1.

(Appearance inspection method)

The appearance inspection method of the test object 2 using the appearance inspection device 1 includes: the step of transporting the test object 2; the step of obtaining the image data of the surface of the transported object 2; The processing steps, the above-mentioned image data acquisition step includes: the step of illuminating a partial area of the surface of the test object 2 with a plurality of illuminators 4; the step of diffusing the illuminating light of the illuminator 4 with the diffusion plate 5; and the camera 3 continuous shooting Steps in the above area.

(Transfer steps)

In the transport step, the test object 2 is placed on a transport unit such as a movable stage or a belt conveyor and transported. As a method of placing the test object 2, an operator may place it, or the appearance inspection device 1 may be assembled into a production facility or the like, and may be automatically placed on the transport unit from another device or the like.

(Image data acquisition procedure)

In the image acquisition step, image data of the surface of the test object 2 is acquired. The image data acquisition step includes a step of illuminating a local area on the surface of the subject 2 with a plurality of illuminators 4; a step of diffusing the illumination light of the illuminator 4 by the diffuser plate 5; and a step of continuously photographing the aforementioned area by the camera 3.

(Irradiation step)

In the irradiation step, a plurality of illuminators 4 irradiate a local area on the surface of the test object 2. The plurality of illuminators 4 are arranged so that the irradiation direction is toward the imaging direction of the camera 3.

(Light diffusion step)

In the light diffusion step, the diffusion plate 5 diffuses the illumination light of the illuminator 4. The illumination light irradiated from the plurality of illuminators 4 is diffused through the diffuser plate 5, so that the above-mentioned illumination light incident on the camera 3 can be prevented from being specularly reflected on the surface of the test object 2, and the diffused light can be at least enough to cover the above-mentioned area. illuminate.

(Shooting steps)

In the photographing step, the camera 3 continuously photographs the above-mentioned area. Specifically, the camera 3 continuously photographs a part of the surface of the test object 2 passing through the above-mentioned diffused light, and converts it into image data. At least a part of the surface area of the test object 2 irradiated by the plurality of illuminators 4 becomes the photographing area photographed by the camera 3 in the photographing step.

(Image processing steps)

In the image processing step, the image data acquired by the aforementioned camera 3 is processed. Specifically, the image processing unit generates an overall image of the surface of the test object 2 based on the partial image data of the surface of the test object 2 sent from the camera 3, and determines whether there is an abnormal part in the overall image, The above-mentioned overall image and the judgment result are displayed on a monitor or the like.

As the upper limit of the time from the acquisition of the image of the surface of the test object to the end of the inspection of the entire area of the surface of the test object by the image processing unit, 8 seconds are preferable, 6 seconds are more preferable, and more preferable 4 seconds. The lower limit of the above-mentioned processing time is not particularly limited, and may be, for example, 1 second. When the above-mentioned processing time exceeds the above-mentioned upper limit, the inspection efficiency may decrease. In addition, "until the inspection is completed" means that the overall image is generated by the image processing unit, the presence or absence of abnormal parts in the overall image is determined, and the overall image and the determination result are displayed on a display or the like.

(advantage)

According to the above-mentioned visual inspection apparatus, while acquiring the image data of the test object conveyed by the conveying unit, the image processing unit generates an image of the entire surface of the test object by processing the image, and performs the overall image It can judge whether there are abnormal parts, so the inspection processing speed is excellent, so that the appearance inspection can be performed efficiently. Since the image data is captured by the camera for each partial imaging area of the surface of the object to be inspected, it is relatively easy to increase the transport speed and increase the inspection processing speed compared to imaging the entire surface at one time. Since the appearance inspection device has a plurality of illuminators, even if the conveying speed of the test object is increased, sufficient illuminance for the camera to acquire image data can be provided, and the inspection processing speed can be further increased. Furthermore, since the irradiating directions of the diffuser plate and the plurality of luminaires are respectively vertical, the illuminating light is efficiently diffused, the generation of halo can be effectively suppressed, and high-precision appearance inspection can be performed.

(Other implementation methods)

All the features in the embodiments disclosed above are illustrative and not restrictive. The scope of the present invention is not limited by the structure of the foregoing embodiment, but is determined by the claim, and includes content equivalent to the claim and all changes within the scope of the claim.

The diffuser 5 can also be a transparent rod-shaped member having an arc shape or the like in cross section.

In addition, a case where the imaging direction C of the camera 3 is arranged obliquely with respect to the surface of the object 2 is also within the scope of the present invention.

(Example)

Hereinafter, the present invention will be described in further detail based on examples, but the description based on the examples is not intended to limit the present invention.

As the test object, a substrate in which a plurality of wafer patterns of 0.3 mm in length and 0.6 mm in width were formed on the substrate was prepared. The surface of the substrate was screen-printed with Ru paste with a film thickness of 100 μm, which was 60 mm in length and 70 mm in width. The paste coats the substrate. The paste-coated substrate was placed on a stage and transported in a horizontal direction at a transport speed of 140 m/sec, and partial images of the substrate surface were continuously captured for each imaging area.

As shown in FIG. 1, the camera is arranged such that its imaging direction is perpendicular to the surface of the test object, and the illuminator is arranged symmetrically with respect to the imaging direction of the camera on the downstream and upstream sides of the conveying direction. The cross section of the diffuser plate is arc-shaped and is arranged at a position 3 mm away from the substrate, and the angle θ from one end of the diffuser plate to the other end is 150°. In addition, the "distance between the diffuser plate and the substrate" is the distance between the both ends of the diffuser plate and the surface of the paste-coated substrate.

The camera, illuminator, and diffuser used in the image acquisition section are as follows.

Camera: CMOS linear camera (manufactured by TELEDYNE DALSA: LA-HM-16K07A, 16384 pixels, 3.52μm pixel size)

Illuminator: White LED light source (manufactured by Yutecnoroji: UFLS-75-12W-UT)

Diffusion plate: Diffusion plate (made by 3M Company: 3635-70, light transmittance about 60%, thickness 0.8mm), and semicircular polycarbonate plate (colorless and transparent, inner diameter Φ14mm, outer diameter Φ18mm)

In the image processing unit, the image data obtained by the above-mentioned camera was used as a whole image, and the occurrence of halation was visually confirmed.

In the embodiment, by changing the camera gain, the number and angle of the illuminator, and the distance between the illuminator and the diffuser, it is confirmed whether there is halo. In the comparative example, no diffuser is provided. The results are shown in Table 1. In addition, the "angle of the illuminator" is the angle between the illuminating direction of the illuminator and the conveying surface (horizontal plane).

(Table 1)

To Camera gain Number of luminaires Angle of the lower side illuminator Angle of upper side illuminator Distance between illuminator and diffuser (mm) Halo Test example 1 2.8 4 25 55 20 none Test example 2 2.8 4 40 60 20 none Test example 3 2.8 4 25 45 20 none Test Example 4 2.8 2 - 45 20 none Test Example 5 2.8 2 - 45 5 none Test Example 6 3.5 2 - 45 5 none Test Example 7 2.8 2 - 45 0 none Test Example 8 2.8 4 30 60 10 none Test Example 9 2.8 4 25 60 10 none Test Example 10 2.8 4 25 55 10 none Comparative example 1 2.8 2 - 45 - have

When the number of illuminators is 4, the lower illuminator is the illuminator close to the object to be inspected, and the upper illuminator is the illuminator close to the camera side. The angle when the number of illuminators is two is described in the column of the angle of the upper illuminator for convenience.

In Examples 1 to 10 in which the diffuser plate was arranged, no halo was generated. The overall image of Example 1 is shown in FIG. 4 after being enlarged. In Examples 4-7 in which there are two illuminators, although no halo is generated, the image is relatively dark. In this embodiment, it can be seen that proper inspection can be performed when four illuminators are installed. In Comparative Example 1 where the diffuser was not provided, although the number of illuminators was also two, it was confirmed that halo occurred. The overall image of Comparative Example 1 is shown in FIG. 5 after being enlarged. The white lines extending in the left-right direction of the paper surface in FIG. 5 are halos.

Next, under the condition that the Ag paste is applied to the substrate and the illuminator is a blue LED light source, the cross-sectional shape of the diffuser plate is a circular arc sample, and the cross-sectional shape of the flat plate sample is rectangular. For comparison. The surface of the flat plate-shaped diffusion plate opposite to the surface of the paste-coated substrate was arranged at a position 3 mm away from the surface of the paste-coated substrate. The number of illuminators is 4, the angle of the lower illuminator is 30°, the angle of the upper illuminator is 70°, and the distance between the upper illuminator and the diffuser is 10mm. In addition, the distance between the upper illuminator and the lower illuminator and the flat plate-shaped diffusion plate refers to the distance from the luminaire to the flat plate-shaped diffusion plate in the irradiation direction of each illuminator.

In the example and the comparative example, by changing the conveying speed, camera exposure time, gain, aperture, brightness of the illuminator, and the distance between the lower illuminator and the diffuser, it was confirmed whether there was halation. The results are shown in Table 2. In addition, the "luminance (%) of the illuminator" represents the ratio of 3000lm to the output beam of the illuminator.

(Table 2)

To Conveying speed (mm/sec) Camera conditions The brightness of the illuminator (%) The distance between the lower side illuminator and the diffuser (mm) Halo Exposure time (µm) Gain aperture Test Example 11 140 30 5 5 100 10 none Test Example 12 70 55 3.5 5 100 10 none Comparative example 2 140 30 3.5 6.5 94 15 none Comparative example 3 140 30 3.5 6.5 94 13 none Comparative example 4 140 30 3.5 5 94 13 none Comparative example 5 140 30 3.5 5 100 13 none Comparative example 6 70 30 3.5 5 100 13 none Comparative example 7 70 55 3.5 5 100 13 none Comparative example 8 140 30 4.5 5 100 13 none Comparative example 9 140 30 5 5 100 13 none

In Examples 11 to 12 in which a diffusion plate with a semicircular cross section was used, no halo was generated, and the overall image after processing the image data of the camera was also bright and clear, and suitable for inspection. On the other hand, in Comparative Examples 2 to 9 in which a flat plate-shaped diffuser was used, although no halation was generated, the overall image was dark, and it was not suitable for high-precision inspection.

Industrial applicability

As described above, the appearance inspection device of the present invention can effectively prevent the occurrence of halation, and therefore can increase the conveying speed to realize an efficient appearance inspection, and is therefore suitable for the production of electronic components.

1: Visual inspection device 2: Object to be inspected 3: camera 4: Illuminator 5: diffuser 51: Through hole C: Shooting direction (the central axis of the camera's imaging surface) P: Irradiation direction (central axis of the beam of illuminating light) R: radius X: conveying direction W: Length (length of the long side of the diffuser) θ: Angle

Fig. 1 is a schematic side view showing an appearance inspection apparatus according to an embodiment of the present invention. Fig. 2 is an enlarged schematic view showing a diffuser plate included in the appearance inspection apparatus of Fig. 1. Fig. 3 is a perspective schematic view of the diffuser plate of Fig. 2. Fig. 4 is an enlarged image in which a part of the entire image of the surface of the test object is enlarged. FIG. 5 is an enlarged image of a partial enlargement of the entire image of the surface of the test object that is different from that of FIG. 4.

1: Visual inspection device

2: Object to be inspected

3: camera

4: Illuminator

5: diffuser

C: Shooting direction (the central axis of the camera's imaging surface)

P: Irradiation direction (central axis of the beam of illuminating light)

X: conveying direction

Claims (6)

An appearance inspection device, comprising: a conveying part for conveying an inspected object; a camera for photographing a photographing area of each part of the surface of the inspected object conveyed by the conveying part; and a plurality of illuminators , Illuminating the illumination light toward the shooting area; a diffuser plate arranged in the irradiating direction of the illuminator; and an image processing unit that processes the image data obtained by the camera, the diffuser plate and the multiple The respective illumination directions of the illuminators are respectively vertical, wherein the test object is the surface of a plate-shaped body or the surface of an article placed on the surface of the plate-shaped body, and the diffuser is the plurality of illuminators A common diffuser plate, the diffuser plate is partly cylindrical, the cross section of the diffuser plate is arc-shaped, and the conveying part includes a belt conveyor or a carrier for placing and transporting the test object The object stage, the camera is a linear sensor camera, the illumination directions of the respective illuminators of the plurality of illuminators cross each other on the shooting area, and the intersection point is aligned with the arc of the cross section of the diffuser plate The center points are the same, the multiple luminaires are installed on a mounting pillar with a variable illuminating direction, The light transmittance of the diffusion plate is more than 50%, and the diffuse reflectance is more than 90%, and the distance between the plurality of illuminators and the diffusion plate is 20 mm or less. The appearance inspection device according to claim 1, wherein the photographing direction of the camera is perpendicular to the photographing area, and the plurality of illuminators are symmetrically arranged with the photographing direction of the camera as a reference. The appearance inspection apparatus according to claim 1, wherein the respective irradiation directions of the plurality of illuminators respectively cross on the photographing area. The visual inspection device according to claim 1, wherein the conveying speed of the conveying section is 70 mm/sec or more. The visual inspection device according to claim 1, wherein the number of pixels of the camera is 8000 or more, and the resolution is 7.00 μm/pixel or less. The visual inspection device according to claim 1, wherein from the acquisition of an image of the surface of the test object to the end of processing and inspection of the entire area of the surface of the test object by the image processing unit, Less than 8 seconds.

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