JP2015225003A - Appearance inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an appearance inspection device that can detect a crack of a surface of an inspected body with high sensitivity even if the crack thereof is shallow.SOLUTION: An appearance inspection device according to the present invention is a device that inspects a surface of a planar inspected body, and the appearance inspection device comprises: (a) a light source that irradiates the surface of the inspected body with a plurality of mutually adjacent parallel linear light; and (b) a linear light reception unit that is arranged at a location where any of the plurality of mutually adjacent parallel linear light reflected upon the surface of the inspected body or passing through the inspected body is received or at a location in the vicinity of the location, and is parallel to the linear light. If there is a surface crack of the inspected object, when the plurality of linear light with which the surface of the inspected body irradiated is reflected at a portion of the crack or passes through the portion thereof to enter the light reception unit, the plurality of linear light is incident upon the light reception unit at a mutually different angle. Thus, even if the crack is shallow, a defect of the crack can be detected by any of reflection light/transmission light, which in turn can detect a defect of the surface of the inspected body with high sensitivity as a whole.

Description

  The present invention relates to the appearance of an object to be inspected, such as defects such as wrinkles and irregularities on the surface of a planar object to be inspected, the shape of the object to be inspected, and the placement and dimensions of an attachment attached to the object to be inspected. It relates to a device to be inspected.

  Conventionally, in order to inspect defects on the surface of a planar inspection object such as a smartphone main body (housing) or a glass substrate mounted on the surface of the inspection object, the inspection object is moved and perpendicular to the moving direction. A method of irradiating a surface of an object to be inspected with a linear light and receiving the reflected light with a sensor is used. For example, Patent Document 1 discloses that a surface of a moving strip is irradiated with a single line of light, and a reflected image of the linear light reflected on the surface of the strip is captured by a time delay integration type video camera. An apparatus for inspecting the surface of the strip for defects is described.

JP 2004-132800 JP

  In Patent Document 1, a single linear light is irradiated on the surface of an object to be inspected, and the linear light reflected there is a sensor (TDI) composed of a one-dimensional pixel array of a time delay integration type video camera (TDI camera). Sensor). Therefore, when unevenness or wrinkles (defects) on the surface of the object to be inspected are shallow, depending on the angle, the intensity drop due to defects in the reflected linear light is slight, and detection is difficult. was there.

  The problem to be solved by the present invention is to provide an appearance inspection apparatus that can detect with high sensitivity even if the surface of the object to be inspected has a shallow wrinkle.

The present invention made to solve the above problems is an apparatus for inspecting the surface of a planar object to be inspected,
a) a light source for irradiating the surface of the object to be inspected with a plurality of parallel linear lights close to each other;
b) The line arranged at a position where one of the plurality of parallel linear lights received by the surface of the object to be inspected or transmitted through the object to be inspected, or a position in the vicinity thereof And a linear light receiving portion parallel to the light beam.

  Here, “close to each other” for a plurality of parallel linear lights means that the distance between the plurality of parallel linear lights is smaller than the size of the defect to be detected. In addition, with respect to the position of the linear light receiving unit, the “position in the vicinity of the light receiving position” refers to a position between a plurality of parallel linear lights or from the end of the plurality of parallel linear lights. A position that is separated by a distance shorter than the entire width of the plurality of linear lights.

  In the appearance inspection apparatus according to the present invention, a plurality of linear lights are irradiated on the surface of the object to be inspected, so that it is reflected by a defect on the surface of the object to be inspected, or is transmitted through the portion of the defect of the object to be inspected. The reflected / transmitted lights of the plurality of linear lights are incident at different angles when entering the light receiving unit. For this reason, even if it is a shallow ridge, the defect can be detected by any reflected light / transmitted light, and the defect on the surface of the object to be inspected can be detected with high sensitivity as a whole.

  It is desirable that the incident angle of the linear light from the light source (the angle formed by the optical path of the linear light and the normal surface on the surface of the object to be inspected) is 10 degrees or less.

  By reducing the incident angle in this way, the distance between the light source and the detection unit (the distance in the direction parallel to the surface of the object to be inspected) is reduced, and the overall length of the appearance inspection apparatus can be reduced. In addition, it becomes easier to inspect defects on the inspection object with high transparency. That is, in the case of an object to be inspected with high transparency, the smaller the incident angle, the greater the proportion of light that is transmitted at a location where there is no defect, making it easier to detect the reflected light from the defect.

  The linear light receiving unit may receive no direct reflected light of a plurality of parallel linear lights (this is referred to as “scattered light receiving type”), or any one of them The reflected light of the linear light may be directly received (this is referred to as “direct light receiving type”). The scattered light receiving type is suitable for detecting defects such as irregularities, wrinkles, wrinkles, etc. that are colorless or the same color as the object to be inspected, and the direct light receiving type is a colored or shaded foreign object, black spot, dirt, etc. Suitable for detecting defects.

  The linear light receiving unit can extract one linear data from an image captured by a camera. With this configuration, a general camera can be used without using an expensive line sensor. Further, in the case of a line sensor, it is necessary to accurately set the position where linear light should be received, and the setting is troublesome. However, in the case of a camera, such troublesome position setting is not necessary.

The visual inspection apparatus according to the present invention further includes:
It is desirable to provide a moving mechanism for moving the object to be inspected in a direction not parallel to the plurality of linear lights.

  Thereby, it becomes possible to inspect a wide range of the surface of the object to be inspected. In the case of the direct light receiving type, an image of the surface of the object to be inspected can be obtained by accumulating the direct reflected light received by the linear light receiving unit. In addition, it is also possible to inspect the attachments.

  When such a moving mechanism is provided, it is desirable to further provide a reversing mechanism for reversing the front and back of the object to be inspected at one end thereof. Thus, after moving the object to be inspected in one direction by the moving mechanism and inspecting one surface, the front and back are reversed by the reversing mechanism, and the object to be inspected is moved in the reverse direction by the moving mechanism. Now you can inspect the other side. This reduces the size and cost of the appearance inspection apparatus.

  The plurality of parallel linear lights close to each other can be produced by covering a part of a linear light source with a light shielding tape parallel to the longitudinal direction. For example, two parallel linear lights can be obtained by sticking a light-shielding tape covering the entire length in the longitudinal direction at the center in the width direction of the linear light source. Moreover, three parallel linear lights can be obtained by attaching two light shielding tapes slightly apart in the width direction.

  The appearance inspection apparatus according to the present invention may further include an image sensor. As described above, with the direct light receiving type, it is possible to inspect the outer shape of the object to be inspected by providing the moving mechanism with only the linear light source, but the inspection speed is further improved by providing the image sensor.

  According to the appearance inspection apparatus according to the present invention, even if the inspected object has a shallow wrinkle, it can be detected with high sensitivity.

1A and 1B are a side view and a top view showing a schematic configuration of an appearance inspection apparatus according to an embodiment of the present invention. The schematic top view of the carrier of the Example. Schematic of the light emission surface of the light source for defect inspection of the Example. Side view showing schematic configuration of defect inspection unit of same embodiment (a), front view of line camera (b), top view (c) of inspection object irradiated with light from defect inspection light source, and line The top view (d) which shows a visual field. The side view (a) which shows schematic structure of the inversion part of the Example, a front view (b), and a top view (c). The figure which shows operation | movement of the inversion part of the Example. The schematic diagram of the light reflected in the defect inspection part of the Example. Schematic diagram (a) of a light emitting surface of a defect inspection light source of a visual inspection apparatus according to another embodiment of the present invention, and an outline showing the relationship between the light irradiated from the defect inspection light source surface and the line field of view Figure (b). The side view which shows the position of the permeation | transmission camera of the test | inspection part which concerns on another Example. The defect image detected with the external appearance inspection apparatus of the Example.

An appearance inspection apparatus 1 according to an embodiment of the present invention will be described with reference to FIGS.
The appearance inspection apparatus 1 detects defects such as a glass substrate on the front surface (referred to as “surface A”) of the smartphone and a flaw on the case on the back surface (referred to as “surface B”), and further on the surface. This is to inspect whether the hole for the camera lens (lens hole) provided in the microphone or the case on the back side is in the correct place. In addition, as a to-be-inspected object, it is not limited to a smart phone, What is necessary is just the planar thing in which the front and back of a to-be-inspected object reflect light.

  As shown in FIG. 1, the appearance inspection apparatus 1 includes a mounting / removal unit 10 that attaches or removes the inspection object S to / from a carrier 51 for carrying the inspection object S, and a defect in the inspection object S. And an inspection unit 20 for inspecting the appearance, a reversing mechanism 60 for reversing the front and back of the object S to be inspected, and a transport unit 50 for transporting the carrier 51 from the loading / unloading unit 10 to the inspection unit 20 and the reversing mechanism 60.

  The mounting / removal unit 10 includes a load mechanism 11 that mounts the inspection object S on the carrier 51, and an unload mechanism 12 that extracts the inspection object S from the carrier 51. Of course, these may be performed manually.

The transport unit 50 includes two parallel rails 52 and a carrier 51 that travels on the rails 52. A linear motor mechanism 53 is provided between the lower surface of the carrier 51 and the two rails 52 (FIG. 1B).
As shown in FIG. 2, two guides 511 having an L-shaped cross-section supporting both sides of the object to be inspected S (shown by dotted lines) and a width adjusting handle 512 for changing the distance between them are disposed on the carrier 51. And a cylinder 513 for fixing the object S to be inspected between the two guides 511.

The inspection unit 20 includes a defect inspection unit 21, an appearance inspection unit 31, and a processing unit 40 connected to them. A display unit 41 is connected to the processing unit 40.
The defect inspection unit 21 includes a defect inspection light source 22 and two line cameras 23a and 23b. The defect inspection light source 22 emits three parallel linear lights. Specifically, a linear light source 22 (length L = about 200 mm, width W = about 21 mm) in which a large number of highly directional blue LEDs are arranged in a line in a line is used, as shown in FIG. In addition, two black light-shielding tapes 24 (width w1 = about 6 mm) pasted at equal intervals w2 (about 3 mm) in the longitudinal direction of the light emitting surface are used.

As shown in FIG. 4A, the defect inspection light source 22 is arranged so as to be irradiated at an incident angle (α) of about 7 degrees with respect to the surface A facing upward of the inspection object S. ing.
As shown in FIG. 4B, the line cameras 23a and 23b move the carrier 51 so that the entire width Lw (see FIG. 1B) of the upper surface of the inspection object S can be imaged by two units. It is juxtaposed perpendicular to the direction and to the left and right. As shown in FIG. 4 (a), both line cameras 23a and 23b have a surface formed by the specularly reflected light from the center in the width direction of the defect inspection light source 22 formed by the camera optical axes of both line cameras 23a and 23b. It is installed so that it almost matches.

  The appearance inspection unit 31 includes an appearance inspection light source 32 and an area camera 33. The area camera 33 is provided so that its optical axis is perpendicular to the upper surface A of the object S to be inspected. The area camera 33 corresponds to the image sensor of the present invention. The appearance inspection light source 32 is an LED light source that is coaxial with the optical axis of the area camera 33 (two-dot chain line in FIG. 1A), and irradiates the entire upper surface A of the inspection object S substantially uniformly. .

  The processing unit 40 is a personal computer provided with a predetermined program, receives data from the line cameras 23a and 23b and the area camera 33, and processes the defects and appearance of the inspection object S by processing as described later. The results are transmitted to a predetermined device and displayed on the display unit 41.

  As shown in FIGS. 5A and 5B, the reversing mechanism 60 includes a reversing hand 61 having a plurality of suction pads 64, a rotary mechanism 62 that rotates the reversing hand 61 by 180 degrees, and moves them up and down. A vertically moving cylinder 63 is provided.

  Below, operation | movement of this external appearance inspection apparatus 1 is demonstrated. The initial position of the carrier 51 is the start end X (FIG. 1B) of the rail 52. When the appearance inspection apparatus 1 is activated, the carrier 51 is moved to the start end X.

  First, the distance between the guides 511 is adjusted by the width adjustment handle 512 of the carrier 51 according to the width Lw of the object S to be inspected. Thereafter, in the mounting / removal unit 10, the inspection object S is placed between the guides 511 with the surface A facing upward by the load mechanism 11 and fixed by the cylinder 513.

The carrier 51 holding the inspection object S is moved to the inspection unit 20 by the linear motor mechanism 53. In the inspection unit 20, first, three parallel lines from the defect inspection light source 22 are formed on the upper surface A of the inspection object S conveyed in the defect inspection unit 21 as shown in FIG. Jo light SL ₃ is irradiated. The image of the surface A irradiated with the linear light SL ₃ is taken by the line cameras 23 a and 23 b and sent to the processing unit 40.

The processing unit 40 extracts only the data of the central light portion of the _three parallel linear lights SL3 from the captured image data as the sensor field of view V as shown in FIG. Make an image (direct light reception type). In this embodiment, the width Ws of the sensor visual field V is approximately 28.35 μm. This sensor visual field corresponds to the linear light receiving portion in the present invention. The processing unit 40 removes noise from the line image using a spatial filter and then performs defect enhancement processing to obtain line inspection data. In the line inspection data, for example, in the case of gradation of 8 bits, the light level when there is no defect is 256, and when there is a defect, it is 256 or less. Based on the line inspection data, the processing unit 40 determines whether or not the surface A of the inspection object S has a defect, transmits the result to a predetermined device, and displays the result on the display unit 41.

  In the appearance inspection apparatus 1, while the inspection object S passes the defect inspection unit 21, the sensor visual field V sequentially moves on the surface A of the inspection object S, and a line image of each linear region is acquired. The acquired line images are sequentially sent to the processing unit 40, where the above processing is performed, and defect inspection / determination is performed. At the same time, the visual inspection apparatus 1 accumulates the data of these sequentially acquired line images, and when one inspection object S passes through the sensor visual field V, the processing unit 40 performs all the line image data. Are integrated to create an entire image of the surface A of the inspection object S. The processing unit 40 cuts out image data (for example, 256 × 256 pixels or 512 × 512 pixels) of a portion including a portion where it is determined that there is a defect earlier from the entire image, and saves it as defect image data. . The defect image is displayed on the display unit 41.

  In the appearance inspection apparatus 1, three parallel linear lights are used as defect inspection light, and the sensor visual field V is arranged so as to be in the central linear light. In the portion where there is no defect on the surface of the body S, only the light of the central linear light enters the sensor visual field V as shown in FIG. On the other hand, as shown in FIG. 7B, the amount of light incident on the sensor visual field V from the central linear light irradiated to the defect D is reduced in the portion where the defect D is present, while 2 on both sides thereof. The linear light of the book is reflected by the defect D, is reflected (diffuse reflection) in a direction other than the regular reflection direction, and enters the sensor visual field V. These lights interfere with each other in the sensor visual field V, and are in a state different from the case of only the regular reflection light of the central linear light when there is no defect D. For this reason, it is possible to detect the defect D, particularly a shallow flaw, with higher sensitivity than in the case of using a single linear light. In order to detect a shallow haze with a single linear light, the incident angle / reflection angle of the light had to be set large (that is, the light source and the camera were placed on the surface of the object S to be inspected). In the appearance inspection apparatus 1, the incident angle of the linear light can be reduced, and as a result, the distance between the defect inspection light source 22 and the line cameras 23a and 23b can be reduced. Thereby, the full length of an apparatus can be made small.

  The inspection object S that has passed through the defect inspection unit 21 is further conveyed, and the linear motor mechanism 53 is stopped when the area image capturing position of the appearance inspection unit 31 is reached. At the area image capturing position, a coaxial LED light source (appearance inspection light source 32) is irradiated on the entire surface A of the inspection object S, and an area image is captured by the area camera 33. The captured area image is sent to the processing unit 40 and subjected to image processing, and it is determined whether the position and shape of the microphone hole match a predetermined position and shape. The processing unit 40 transmits the determination result to a predetermined device and displays it on the display unit 41.

  Thereafter, the carrier 51 is further transported to the other rail end Y (see FIG. 1B) and stopped there. At this time, the reversing hand 61 is positioned below the inspection object S held by the carrier 51 (FIG. 6A). Next, when the vertically moving cylinder 63 is raised and the suction pad 64 on the upper surface of the reversing hand 61 comes into contact with the lower surface B of the inspection object S, the absorption is performed and the adsorption pad 64 is adsorbed on the surface B of the inspection object S. (FIG. 6 (b)). At this time, the lock mechanism of the carrier 51 is released.

  Thereafter, the vertically moving cylinder 63 is further raised (FIG. 6C), and the rotary mechanism 62 rotates the reversing hand 61 by 180 degrees (the direction of the arrow in FIG. 5B). As a result, the front and back of the inspection object S are reversed and the surface B faces upward (FIG. 6D). Thereafter, when the vertically moving cylinder 63 is lowered and the surface A of the inspection object S comes into contact with the carrier 51, the suction by the suction pad 64 is released (6 (e)), and the inspection object S faces the surface B upward. In this state, it is sandwiched between both guides 511 and locked by the cylinder 513.

  Thereafter, the inspection object S is conveyed in the opposite direction, that is, from the rail end Y to the rail end X. First, the appearance inspection unit 31 captures an area image of the surface B, and the defect inspection unit 21 sequentially acquires line image data of the surface B. The operations in the appearance inspection unit 31 and the defect inspection unit 21 are performed in the same manner as in the inspection of the surface A. The appearance inspection unit 31 detects the position and shape of the lens hole in the surface B, and determines the predetermined position and shape. It is determined whether or not. The defect inspection unit 21 inspects and determines whether there is a defect on the surface B.

When the inspection object S is conveyed to the mounting / removal unit 10, the linear motor mechanism 53 is stopped, the lock mechanism is released, and then the unloading mechanism 12 takes out the carrier 51. The taken inspected object S is classified into a non-defective product and a defective product (or a product requiring re-inspection) according to the appearance of the surface A and the surface B and the result of the defect inspection.
At the rail end Y, after the carrier 51 is separated from the reversing mechanism 60, the rotary mechanism 62 is rotated again by 180 degrees, and the reversing hand 61 is returned to the state where the suction pad 64 faces upward.

  In this appearance inspection apparatus 1, since there is one inspection section and the inspection object S reciprocates there, the apparatus is downsized. Moreover, since the inspection site including the defect inspection light source 22 and the line cameras 23a and 23b may be one of the defect inspection units 21, the equipment cost can be reduced.

  In the appearance inspection apparatus 1, since the inspection object S is transported by the linear motor mechanism 53, the inspection object S moves smoothly, and distortion and noise generated in the captured image (line image, area image) are minimized. It is possible to increase the sensitivity of defect detection while limiting to the limit. In addition, the conveyance speed can be increased while maintaining high sensitivity, and the inspection processing capability can be increased.

FIG. 8A is a schematic view of the light emitting surface of the defect inspection light source 25 of the appearance inspection apparatus 1 according to another embodiment of the present invention. This defect inspection light source 25 is obtained by attaching one black shading tape 26 (width w3 = about 9 mm) in the longitudinal direction to the center in the width direction of the light emitting surface (width W = about 21 mm ) of illumination. . In this embodiment, the processing unit 40 includes a portion (light-shielding portion) between _two parallel linear lights SL2 in the images taken by the line cameras 23a and 23b, as shown in FIG. 8B. Is the sensor visual field V, and the data of that portion is extracted and used as line image data (scattered light receiving type). The detection of the defect will be described in the above example (in the case of gradation of 8 bits). When there is no defect, the reflected light of the _two linear lights SL2 is not received, so that the light level is low (line camera 23a). If there is a defect, scattered light due to the defects of the _two linear lights SL2 is incident on the sensor visual field V, and the light is reduced. The level of will be greater than this.

  10A to 10E show images of surface defects of the glass substrate detected by the appearance inspection apparatus 1. FIG. These images are of the scattered light receiving type and are images in a wider range than the above-described defect image data. 10A is an image on the CF side, and FIGS. 10B to 10E are images on the surface on the TFT side. As is clear from these images, the appearance inspection apparatus 1 can detect defects with high sensitivity.

The above embodiment is an example of the present invention, and appropriate modifications, corrections, and additions are allowed within the scope of the present invention.
For example, in the above embodiment, the inspection of the appearance of the inspected object uses data imaged by an area camera different from the line camera. However, the line data of the line camera is integrated to create one image. However, it may be used instead of the area image. In this case, both the defect and the appearance can be inspected with only the line camera, so that the equipment cost can be further reduced.

Also, by adjusting the SN ratio of defects captured by the line camera by changing the width and color of the light-shielding tape attached to the light-emitting surface of the defect inspection light source according to the type of inspection object and the type of defect to be detected This makes it possible to detect defects with higher sensitivity.
Furthermore, in the said Example, although it was set as the structure which detects the surface defect by receiving the reflected light of the light source for defect inspection irradiated to the to-be-inspected object, when the to-be-inspected object permeate | transmits a part of light As shown in FIG. 9, a transmission line camera 35 that receives the transmitted light may be further provided. In this case, a defect can be detected by performing the same processing as the line captured image acquired by the line cameras 23a and 23b of the above embodiment on the captured image of the transmission line camera 35.

DESCRIPTION OF SYMBOLS 1 ... Appearance inspection apparatus 10 ... Installation / extraction part 11 ... Load mechanism 12 ... Unload mechanism 20 ... Inspection part 21 ... Defect inspection part 22, 25 ... Light source 23a, 23b ... Line camera 24, 26 ... Light shielding tape 31 ... Appearance inspection unit 32 ... Light source for appearance inspection 33 ... Area camera 35 ... Transmission line camera 40 ... Processing unit 41 ... Display unit 50 ... Conveying unit 51 ... Carrier 511 ... Guide 512 ... Width adjustment handle 513 ... Cylinder 52 ... Rail 53 ... Linear motor mechanism 60 ... reversing mechanism 61 ... reversing hand 62 ... rotary mechanism 63 ... vertical movement cylinder 64 ... suction pad D ... defect S ... inspection object V ... sensor field of view

Claims (7)

An apparatus for inspecting the surface of a planar inspection object,
a) a light source for irradiating the surface of the object to be inspected with a plurality of parallel linear lights close to each other;
b) The line arranged at a position where one of the plurality of parallel linear lights received by the surface of the object to be inspected or transmitted through the object to be inspected, or a position in the vicinity thereof And a linear light receiving part parallel to the light beam.   The appearance inspection apparatus according to claim 1, wherein an incident angle of the linear light from the light source is 10 degrees or less.   The visual inspection apparatus according to claim 1, wherein the linear light receiving unit extracts one linear data from an image captured by a camera.   The visual inspection apparatus according to claim 1, further comprising a moving mechanism that moves the object to be inspected in a direction not parallel to the plurality of linear lights.   The visual inspection apparatus according to claim 4, further comprising a reversing mechanism that reverses the front and back of the object to be inspected at one end of the moving mechanism.   6. The plurality of parallel linear lights close to each other are produced by covering a part of a linear light source with a light shielding tape parallel to the longitudinal direction thereof. Appearance inspection apparatus as described.   The visual inspection apparatus according to claim 6, further comprising an image sensor.