JP2011203132A - Visual inspection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a visual inspection apparatus capable of accurately checking defects of optical elements.SOLUTION: The visual inspection apparatus for detecting the defects of a substrate 7 includes a plurality of low-magnification camera light sources 3 obliquely irradiating a plane of the substrate 7 with light respectively and arranged across the substrate 7; a low-magnification camera 4 having an optical axis in a direction intersecting with those of these low-magnification camera light sources 3 and imaging the light irradiated from the low-magnification camera light sources 3 and reflected from or transmitted through the substrate 7; a high-magnification camera light source 5 vertically irradiating the plane of the substrate 7 with light; and a high-magnification camera 6 having an optical axis identical with that of this high-magnification camera light source 5 and imaging the light irradiated from the high-magnification camera light source 5 and reflected from the substrate 7.

Description

  The present invention relates to an appearance inspection apparatus that detects a defect in an optical substrate.

  Conventionally, determination of the presence or absence of defects due to scratches on the optical surface of an optical element or dust adhering to the optical element during the production of the optical element is performed with a camera within the effective area range of the optical element, and the captured image is displayed on the screen. Displayed above, and this is done by visual confirmation by the operator. And the external appearance inspection apparatus which performs the pass / fail determination of an optical element is known about the defect identified by such visual confirmation as described in patent documents 1-5.

Patent Document 1 describes an appearance inspection apparatus that captures an image of an optical device with a single camera and displays the captured image together with a frame image indicating an outer region and an effective region of the optical device.
In Patent Document 2, an inspection table, an inspection head having an imaging device movable relative to the inspection table, an image input from the imaging device and a reference image input in advance are compared, and an inspection target An appearance inspection apparatus including a determination apparatus that determines the quality of an object is described.
Patent Document 3 describes a quartz substrate inspection method in which light is obliquely applied to a quartz substrate and the light is observed in a dark field by an imaging system arranged perpendicular to the quartz substrate.

Patent Document 4 describes a lighting device for surface inspection that includes a plurality of LEDs and a cylindrical lens that is arranged corresponding to each of the LEDs and that is set so that light gathers in a certain surface area of the inspection object. ing.
Patent Document 5 discloses an appearance inspection system in which a plurality of subjects are arranged, defects are evaluated from images obtained by illuminating the subject with light, and evaluation is displayed in association with each subject. Are listed.

JP 2008-139235 A Japanese Patent Laid-Open No. 10-068615 JP 2002-277403 A JP 2004-354047 A Japanese Patent Application Laid-Open No. 2008-24969

However, the device described in Patent Document 1 has only a low-magnification camera, and the accuracy of determining the size of a substrate defect is insufficient.
Also, if the camera is of a high magnification, it is not possible to image the entire substrate plane at the same time, so it is necessary to move the camera or substrate to image the entire substrate. As a result, the inspection process time is extended.

Since the inspection head having the imaging device moves in the device described in Patent Document 2, the positional relationship between the imaging device and the light source changes when the inspection head is moved, so that defect detection accuracy is lacking.
The one described in Patent Document 3 observes the quartz substrate with a single imaging system. Therefore, as in Patent Document 1, only a low-magnification camera has insufficient accuracy to determine the size of a substrate defect. Since the image of the substrate portion having no defect is picked up only by the magnification camera, the inspection process time is extended.

The device described in Patent Document 4 is a lighting device for surface inspection with increased light source utilization efficiency, and the camera for imaging uses the conventional configuration, and thus has the problem of Patent Document 1 described above.
The one described in Patent Document 5 is an appearance inspection system that inspects a plurality of subjects at the same time, and the inspection technique and configuration thereof are the same as those in the prior art, and have the problem of Patent Document 1 described above.

  The objective of this invention is providing the external appearance inspection apparatus which can confirm the defect of an optical element accurately.

[Application Example 1]
The appearance inspection apparatus according to this application example is an appearance inspection apparatus that detects a defect of a substrate, and irradiates light obliquely with respect to the plane of the substrate, and a plurality of low magnifications arranged with the substrate interposed therebetween. A light source for cameras and a low-magnification camera having an optical axis in a direction intersecting with the optical axes of these low-magnification camera light sources and imaging light that is irradiated from the low-magnification camera light source and reflected or transmitted from the substrate And a light source for a high-magnification camera that irradiates light perpendicular to the plane of the substrate, and has the same optical axis as the optical axis of the light source for the high-magnification camera and is irradiated from the light source for the high-magnification camera And a high-magnification camera that captures an image of light reflected by the substrate.

In the appearance inspection apparatus according to the application example, since the low-magnification camera and the high-magnification camera are provided, the entire plane of the substrate is imaged by the low-magnification camera, and the presence / absence of the defect and its location are confirmed, and then confirmed. The details of the defect can be confirmed by imaging the location of the defect with a high-magnification camera. For this reason, if the entire substrate is checked with a low-magnification camera and there is a defect, it is only necessary to check the details with a high-magnification camera. The shape, size, etc. can be confirmed. Therefore, the entire substrate can be confirmed, but the details of the defect cannot be confirmed, or the details of the defect can be confirmed, but it takes time to confirm the entire substrate, and there is no fear that the inspection process time is extended.
Therefore, in the appearance inspection apparatus according to the application example, it is possible to efficiently and accurately check the substrate defect.

[Application Example 2]
The visual inspection apparatus according to this application example preferably includes a display device that displays in parallel the image data captured by the low-magnification camera and the high-magnification camera.

  The visual inspection apparatus according to the application example includes a display device that displays the image data of each of the low-magnification camera and the high-magnification camera, so that an image captured by only one apparatus can be confirmed on the spot. it can. Therefore, the inspection workability is good and the defect of the substrate can be easily confirmed.

[Application Example 3]
In the appearance inspection apparatus according to this application example, the size of a defect on the surface of the substrate is calculated based on image data captured by the high-magnification camera, and it is determined whether the size of the defect is within an allowable range. It is preferable to have a determination unit.

  The visual inspection apparatus according to the application example described above includes a determination unit that calculates the size of a defect based on image data captured by a high-magnification camera and determines whether the size is within an allowable range. Therefore, the pass / fail judgment of the substrate can be easily performed, the workability of the appearance inspection is good, and the inspection process time can be shortened.

[Application Example 4]
In the appearance inspection apparatus according to this application example, when the detected maximum dimension of the defect is less than 10 μm, the substrate is determined to be an acceptable product, and when the detected maximum dimension of the defect is 10 μm or more, the substrate is determined. It is preferable to provide a pass / fail determination means for determining a rejected product.

  In the appearance inspection apparatus according to the application example described above, the substrate is determined to be acceptable if the maximum dimension of the detected defect is less than 10 μm, and the substrate is determined to be unacceptable if the maximum dimension of the detected defect is 10 μm or more. Since the acceptance / rejection judging means is provided, the acceptance / rejection of the substrate can be easily determined from the image data, the workability is good, and the inspection process time can be shortened.

[Application Example 5]
In the appearance inspection apparatus according to this application example, it is preferable that at least one of the light source for the low magnification camera or the light source for the high magnification camera is an LED.

In the appearance inspection apparatus according to the application example, at least one of the light source for the low-power camera or the light source for the high-power camera is an LED, and therefore has higher brightness and longer life than a case where a fluorescent lamp or the like is used as the light source. Defects can be confirmed more easily and accurately with a high-intensity light source, and the frequency of light source replacement work is kept low, which is significant from the viewpoint of maintenance.

[Application Example 6]
The visual inspection apparatus according to this application example preferably includes a stage on which the substrate is placed and a moving mechanism that moves the stage within a plane of the substrate.

In the appearance inspection apparatus according to the application example described above, a stage and a moving mechanism that moves the stage within the plane of the substrate are provided. Therefore, by simply moving the stage, the low-magnification camera and the high-magnification camera image the substrate. The position can be changed. Therefore, it is not necessary to move the low-power camera, the high-power camera, the light source for the low-power camera, the light source for the high-power camera, and the like, and the configuration of the appearance inspection apparatus can be simplified.
Further, if the low magnification camera, the high magnification camera, the light source for the low magnification camera, the light source for the high magnification camera, and the like are moved, the position adjustment becomes complicated. Also excellent.

It is the schematic of the external appearance inspection apparatus in one Embodiment of this invention. It is a composition schematic diagram for explaining the appearance inspection device in this embodiment. It is a block diagram for demonstrating the external appearance inspection method using the external appearance inspection apparatus in this embodiment. It is the figure which showed an example of the image of the image display part of the external appearance inspection apparatus in this embodiment. It is the schematic for demonstrating the method to calculate the maximum dimension of the defect in this embodiment.

[Configuration of visual inspection equipment]
An appearance inspection apparatus according to an embodiment of the present invention will be described below with reference to the drawings.
The appearance inspection apparatus will be described with reference to FIGS.
FIG. 1 shows a schematic diagram of an appearance inspection apparatus in the present embodiment. FIG. 2 is a schematic configuration diagram for explaining the appearance inspection apparatus according to this embodiment. FIG. 3 is a block diagram for explaining an appearance inspection method using the appearance inspection apparatus according to the present embodiment.
As shown in FIG. 1, an appearance inspection apparatus 1 includes a housing 11, a caster 12 that supports the housing 11 so as to be movable from below, and a stage on which an optical substrate 7 serving as a substrate to be inspected is placed. 2, a low-magnification camera light source 3 that irradiates light obliquely with respect to the plane of the optical substrate 7, and a low-magnification image that captures light that is emitted from the low-magnification camera light source 3 and reflected or transmitted through the optical substrate 7 A high-power camera light source 5 that irradiates light perpendicular to the plane of the optical substrate 7, a high-power lens 9 that receives light emitted from the high-power camera light source 5, and the high power A high-magnification camera 6 that captures an image of the light reflected from the optical substrate 7 on which the light transmitted through the lens 9 is incident. The low magnification camera 4 uses an image with a magnification of, for example, 3 times, and the high magnification camera uses an image with a magnification of, for example, 90 times.

The stage 2 includes an XY stage 21 that can move in two orthogonal directions, and a θ stage 22 that can rotate around the center of the stage 2 placed on the upper surface of the XY stage 21. Yes. The XY stage 21 and the θ stage 22 are arranged so that their central portions are coaxial, and have an XY cavity portion 211 and a θ cavity portion 221 so that light can be transmitted around the center. .
Further, the low-magnification camera light source 3 includes an elongated first low-magnification camera light source 31 having an optical axis oblique to the plane of the optical substrate 7 above the stage 2 and the optical substrate 7 below the stage 2. The second low-magnification camera light source 32 having an optical axis in an oblique direction with respect to the plane. The first low-magnification camera light source 31 and the second low-magnification camera light source 32 employ LEDs as their light sources.

The low-magnification camera 4 is located above the stage 2 and at a position that is not on the reflected optical axis when the optical axis of the first low-magnification camera light source 31 is reflected on the optical substrate 7 and the second low-magnification camera 4 The optical axis of the magnification camera light source 32 is arranged at a position not on the transmitted optical axis that passes through the optical substrate 7.
Further, the high-power camera light source 5 is disposed at the center of the stage 2, that is, above the center of the optical substrate 7, and irradiates the optical substrate 7 with light vertically. The high-magnification camera 6 is disposed above the stage 2 and on the reflected optical axis of the light irradiated by the high-magnification camera light source 5 onto the optical substrate 7. The high-power camera light source 5 can employ a halogen lamp, a mercury lamp, or the like as the light source, and may further employ an LED.

As shown in FIG. 2, the image analysis device 8 as the pass / fail determination means can be freely controlled by a display device 81 that displays image data captured by the low-power camera 4 and the high-power camera 6 and an operator's operation. A drive command unit 82 and an operation input button 83 used for image switching, input of pass / fail judgment criteria described later, and the like are provided.
The stage 2 includes an XY stage drive control unit 21A and a θ stage drive control unit 22A that drive the XY stage 21 and the θ stage 22 based on signals from the drive command unit 82, respectively.

As shown in FIG. 3, the low-magnification image is displayed on the low-magnification image display unit 811 after image data captured by the low-magnification camera 4 is processed by the low-magnification image data processing unit 811A.
The high-magnification image is displayed on the high-magnification image display unit 812 after image data captured by the high-magnification camera 6 is processed by the high-magnification image data processing unit 812A. The image data processed by the high-magnification image data processing unit 812A is also transmitted to the pass / fail determination unit 84.
The acceptance / rejection determination unit 84 includes a comparison unit 841 that compares pass / fail based on the received image data, a storage unit 842 that stores information such as acceptance criteria, and a calculation unit that calculates the size of defects from the image data. 843. When the comparison unit 841 determines pass / fail, the comparison unit 841 displays the result on the pass / fail determination display unit 813 of the display device 81.

Next, the display device 81 will be described with reference to FIG.
FIG. 4 is a diagram illustrating an example of an image on the image display unit of the appearance inspection apparatus according to the present embodiment.
As shown in FIG. 4, the display device 81 includes a rectangular display 810, a low-magnification image display unit 811 displayed on the right half of the display 810, and a high-magnification image display displayed on the left half of the display 810. Unit 812 and a pass / fail determination display unit 813 displayed at the upper left corner of the high-magnification image display unit 812.

  The low-magnification image display unit 811 displays the defect F of the optical substrate, and a high-magnification image region V that includes the defect F is shown to enlarge and display the defect F. An image enlarged in the high-magnification image region V is a high-magnification image display unit 812. The enlarged defect F is displayed on the high-magnification image display unit 812, and its shape and size can be confirmed with the naked eye. Further, a pass / fail determination unit (not shown) calculates the shape and size of the defect F, determines whether or not the acceptance criterion is satisfied, and the result is displayed on the pass / fail determination display unit 813. In this pass / fail judgment display portion 813, for example, “◯” is displayed when the product is acceptable as shown in the figure, and “X” is displayed when the product is unacceptable.

An outline of a calculation method for calculating the shape and size of the defect will be described with reference to FIG.
FIG. 5 is a schematic diagram for explaining a method of calculating the maximum dimension of defects in the present embodiment.
As shown in FIG. 5, the high-magnification image data is identified for each mesh pixel in a calculation unit (not shown), and the size of the high-magnification image data is calculated based on the number of pixels on which the defect F indicated by diagonal lines is displayed. . For example, as shown in the figure, since the horizontal dimension L1 of the defect extends over 5 pixels and the vertical dimension L2 extends over 4 pixels, the maximum dimension _{Lmax of the} defect is determined as follows. When calculated as L, L _max = {(5L) ² + (4L) ² } ^1/2 = (41L ² ) ^1/2 . In the arithmetic unit, the dimension of the defect F is calculated in this way. If the obtained maximum dimension L _max is, for example, 10 μm or less, for example, “◯” is displayed on a pass / fail judgment display section (not shown) as a pass product, and “X” is displayed if it is a reject product.

[Operation of visual inspection equipment]
Next, the operation of the appearance inspection apparatus will be described with reference to FIGS.
The appearance inspection apparatus 1 places the optical substrate 7 on the θ stage 22, so that when the optical substrate 7 is confirmed to be defective or defective, the optical substrate 7 is an acceptable product or an unacceptable product. Whether or not there is is determined using the low magnification camera 4 and the high magnification camera 6. Specifically, the maximum size of the defect is calculated based on the image data captured by the high-magnification camera 6, and for example, if it is 10 μm or less, a pass / fail determination is made such as an acceptable product.

As an appearance inspection method, first, the optical substrate 7 is placed on the θ stage 22. Then, the optical substrate 7 is irradiated by the first low-magnification camera light source 31 and the second low-magnification camera light source 32, and the reflected light and transmitted light are imaged by the low-magnification camera 4. Thereby, the image data of the entire optical substrate 7 by the low magnification camera is displayed on the low magnification image display unit 811.
Further, the optical substrate 7 is irradiated by the high-power camera light source 5 and the reflected light is imaged by the high-power camera 6. Thereby, the image data of the entire optical substrate 7 by the high magnification camera 6 is displayed on the low magnification image display unit 811.

At this time, when the low magnification image display unit 811 confirms the defect F on the optical substrate 7, the drive command unit 82 drives the XY stage 21 and the θ stage 22 so that the high magnification image region V includes the defect F. Let As a result, the enlarged image of the defect F is displayed on the high-magnification image display unit 812.
The maximum dimension of the defect F displayed on the high-magnification image display unit 812 is calculated by the calculation unit 843. At this time, for example, when the maximum dimension of the defect F is 10 μm or less, when the optical unit 7 is stored in the storage unit 842 so as to be determined as an acceptable product, the calculated maximum dimension satisfies the determination criterion of the storage unit 842. It is compared in the comparison part 841 and a pass / fail determination is made. The acceptance / rejection determination result is displayed on the acceptance / rejection determination display unit 813 as, for example, “◯” if the product is a pass product, and “x” if it is a reject product.

In the present embodiment, the following operational effects can be achieved.
(1) In this embodiment, since the low-magnification camera 4 and the high-magnification camera 6 are provided, the entire plane of the optical substrate 7 is imaged by the low-magnification camera 4, and the presence or absence of the defect F and its location are confirmed. Thereafter, the details of the defect F can be confirmed by imaging the confirmed defect F with the high-magnification camera 6. For this reason, if the entire optical substrate 7 is confirmed with the low magnification camera 4 and there is a defect F, the presence or absence of the defect F on the optical substrate 7 and its location can be determined by simply confirming the details with the high magnification camera 6. Further, the details of the defect F, for example, the shape and size of the defect F can be confirmed. Therefore, the entire optical substrate 7 can be confirmed, but the details of the defect F cannot be confirmed, or the details of the defect F can be confirmed, but it takes time to confirm the entire optical substrate 7, and the inspection process time is extended. There is no fear of it.
Therefore, in this embodiment, the defect F of the optical substrate 7 can be confirmed efficiently and accurately.

(2) In this embodiment, since the display device 81 for displaying the image data of the low magnification camera 4 and the high magnification camera 6 is provided, an image captured by only one appearance inspection device 1 is displayed on the spot. Can be confirmed. Therefore, inspection workability is good and the defect F of the optical substrate 7 can be easily confirmed.

(3) In the present embodiment, the maximum dimension L _max of the detected defect F If there is less than 10μm determines optical substrate 7 as accepted products, if the maximum dimension L _max of the detected defect F is not less than 10μm is Since the acceptance / rejection determination unit 84 that determines the optical substrate 7 as a rejected product is provided, the acceptance / rejection determination of the optical substrate 7 can be easily performed from the image data, the workability is good, and the inspection process time can be shortened. it can.

(4) In the present embodiment, since the low-magnification camera light source 3 and the high-magnification camera light source 5 are LEDs, they have higher brightness and longer life than when a fluorescent lamp or the like is used as the light source. In addition, the defect F can be confirmed more easily and accurately by a high-intensity light source, and the frequency of light source replacement work and the like can be kept low, which is significant from the viewpoint of maintenance.

(5) In this embodiment, the XY stage 21 and the θ stage 22 are moved in the plane of the optical substrate 7 by the XY stage drive control unit 21A and the θ stage drive control unit 22A, respectively. The image pickup positions of the low-magnification camera 4 and the high-magnification camera 6 with respect to the optical substrate 7 can be changed simply by moving. Therefore, it is not necessary to move the low-magnification camera 4, the high-magnification camera 6, the low-magnification camera light source 3, the high-magnification camera light source 5, and the like, and the configuration of the appearance inspection apparatus 1 can be simplified.
Further, if the low-magnification camera 4, the high-magnification camera 6, the low-magnification camera light source 3, the high-magnification camera light source 5 and the like are moved, the position adjustment becomes complicated. Also, inspection workability is excellent.

(6) In this embodiment, the low-magnification camera 4 is located above the stage 2 and at a position that is not on the reflection optical axis when the optical axis of the first low-magnification camera light source 31 is reflected by the optical substrate 7. In addition, the optical axis of the second low-magnification camera light source 32 is arranged at a position that is not on the transmitted optical axis that transmits the optical substrate 7. For this reason, there is no fear that the light of the low-magnification camera light source 3 is excessively projected onto the low-magnification camera 4 and the optical substrate 7 cannot be imaged, and the defect F can be detected reliably.

(7) In this embodiment, the first low-magnification camera light source 31 and the second low-magnification camera light source 32 are provided as a plurality of low-magnification camera light sources 3. For this reason, when the flat surface of the optical substrate 7 is coated, if there is only one low-magnification camera light source 3, there is a possibility that irregular reflection of the defect F cannot be observed due to reflection by the coating. In the embodiment, there is no such fear, and the defect F of the optical substrate 7 can be reliably detected.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
In the present embodiment, the LEDs are used as the light sources for all of the low-power camera light source 3 and the high-power camera light source 5, but the present invention is not limited to this. For example, only the light source 31 for the first low-magnification camera may be an LED, and any LED may be used as long as the LED is adopted as one of the light sources.
In the present embodiment, the display 810 is configured to display the low-magnification image display unit 811, the high-magnification image display unit 812, and the pass / fail determination display unit 813 at the same time. One or two may be displayed and the image may be switched.

DESCRIPTION OF SYMBOLS 1 ... Appearance inspection apparatus, 3 ... Light source for low magnification cameras, 4 ... Low magnification camera, 5 ... Light source for high magnification cameras, 6 ... High magnification camera, 7 ... Optical substrate (board | substrate), 81 ... Display apparatus, 84 ... Pass / fail Determination part (determination part), F ... defect, L _max ... maximum dimension

Claims (6)

A visual inspection apparatus for detecting defects in a substrate,
A plurality of low-magnification camera light sources arranged to irradiate light obliquely with respect to the plane of the substrate and sandwich the substrate;
A low-magnification camera having an optical axis in a direction intersecting with the optical axis of these low-magnification camera light sources, and imaging light that is irradiated from the low-magnification camera light source and reflected or transmitted from the substrate;
A high-power camera light source that irradiates light perpendicular to the plane of the substrate;
A high-magnification camera that has the same optical axis as that of the light source for the high-magnification camera and that captures the light emitted from the light source for the high-magnification camera and reflected by the substrate. Inspection device. The appearance inspection apparatus according to claim 1,
An appearance inspection apparatus comprising: a display device configured to display in parallel image data captured by the low-magnification camera and the high-magnification camera. In the appearance inspection apparatus according to claim 2,
An appearance having a determination unit that calculates the size of a defect on the surface of the substrate based on image data captured by the high-magnification camera and determines whether the size of the defect is within an allowable range. Inspection device. The appearance inspection apparatus according to claim 3,
Pass / fail judgment means for judging that the substrate is an acceptable product when the maximum dimension of the detected defect is less than 10 μm, and for judging that the substrate is an unacceptable product when the maximum dimension of the detected defect is 10 μm or more. An appearance inspection apparatus comprising: In the appearance inspection apparatus according to any one of claims 1 to 4,
At least one of the light source for the low magnification camera or the light source for the high magnification camera is an LED. In the appearance inspection apparatus according to any one of claims 1 to 5,
An appearance inspection apparatus comprising: a stage on which the substrate is placed; and a moving mechanism that moves the stage within a plane of the substrate.

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