JP2006071595A - Optical inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect a defect simply, by comparing data obtained by photographing at least two or more inspecting parts in the image of an element to be inspected photographed at one time, using a pair of coupling lenses individually by means of a CCD camera, etc. <P>SOLUTION: The inspection device includes an objective lens facing the element to be inspected, a focusing lens arranged on the optical axis of the objective lens, a splitter arranged on the optical axis of the coupling lens to split this optical axis into two, and an imaging means, arranged on the optical axes split by the splitter. The inspecting device is arranged so that optical distances to the light-receiving surface of this imaging means and the element to be inspected become equal, and the optical axis of the light-receiving surface of the imaging means is not coaxial with the split optical axes. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical inspection apparatus for performing defect inspection in a repetitive pattern of a flat object to be inspected having a repetitive pattern such as a liquid crystal panel, a plasma display panel, and a color filter by using an imaging means such as a CCD camera. More specifically, comparing data obtained by separately capturing at least two or more inspection parts in an image of an object to be inspected at a time by a pair of an objective lens and a coupling lens with a CCD camera or the like. Thus, the present invention relates to an optical inspection apparatus that can detect defects in the image.

  In the manufacturing process of liquid crystal panels, plasma display panels, color filters, etc., for example, the color filter pixels are partially defective in color (white defects), and part of the black matrix protrudes into the pixels. Such defects (black defects) and defects such as foreign matter adhering to the color filter may occur, and such defects need to be detected and eliminated.

Conventionally, defect inspection in a repetitive pattern of a flat inspected object having a repetitive pattern as described above is performed by previously storing the result of image processing of data obtained by photographing the inspection portion of the inspected object with a CCD camera. A device for judging the presence or absence of a defect in the measurement site from comparison with the normal pattern data (for example, refer to Patent Document 1), data obtained by imaging the measurement site with a CCD camera and other sites and CCD An apparatus (see, for example, Patent Document 2) that compares data taken by a camera and image-processed to determine the presence or absence of the above-described defect in a measurement site is disclosed.
JP 06-308036 JP 2004-117150 A

In the former of the above-described conventional apparatus, since there are various patterns of the object to be inspected, it is necessary to previously store normal pattern data in the memory as reference data for each pattern of the object to be inspected, which complicates the process. Become.
Further, in this conventional apparatus, the pattern of the part to be inspected of the object to be inspected is compared with the reference data previously stored in the memory, and the presence / absence of a defect in the inspection part is determined from the difference. Since it is obtained from a workpiece other than the object to be inspected, there is a problem that there is an influence such as a difference in light and shade between the inspected part and the reference data resist.

On the other hand, in the latter of the above-mentioned conventional devices, in order to inspect the inspected part of the object to be inspected, it is necessary to move the optical system such as an objective lens in order to obtain data of other comparative parts. take time.
Moreover, although the data of the above-mentioned comparison part is collected from the same object to be inspected, there may be a difference in density due to uneven application of the resist, for example, and there are problems such as the influence of the difference in density.

  The apparatus of the present invention includes an objective lens facing an object to be inspected, an imaging lens disposed on the optical axis of the objective lens, a beam splitter for dividing the optical axis of the coupled lens into a plurality of optical axes, An inspection apparatus having imaging means arranged on at least two optical axes divided by a beam splitter, wherein the optical distances between the light receiving surface of the imaging means and the object to be inspected are equal to each other And the optical axes of the light receiving surfaces of the imaging means respectively disposed on the at least two optical axes are not coaxial with the divided at least two optical axes.

  The apparatus of the present invention is characterized in that the optical axis of the light receiving surface of the imaging means can be moved toward and away from each of the optical axes divided into the at least two optical axes.

In the apparatus of the present invention, since the optical axis of the light receiving surface of the imaging unit is not coaxial with the divided optical axis, one image of the object to be measured obtained by the objective lens by the imaging unit such as each CCD camera is included. The different parts (measurement part and comparison part) can be photographed.
For this reason, it is not necessary to store the reference pattern in advance according to the pattern of the object to be inspected, and the operation can be easily performed.

In addition, since the part to be inspected and the comparative part are very close to each other, the influence of resist coating unevenness on the object to be inspected is small, and processing for canceling the difference in density of the resist is unnecessary.
In addition, the movement of the objective lens, the focusing operation and the like need only be performed once, and the inspection can be performed in a short time.

  Since the optical axis of the light-receiving surface of the imaging means can move in parallel with the divided optical axis, the apparatus of the present invention can capture the image of the measurement site and the image of the comparison site in a substantially congruent state. Thus, the comparison between the two can be performed very easily.

Hereinafter, an optical inspection apparatus as an embodiment of the present invention will be described with reference to FIGS.
As shown in FIG. 1, this inspection apparatus 1 includes an objective lens 3 disposed opposite to an object to be inspected 2 and an imaging lens 4 coaxial with the optical axis 10 of the objective lens 3. In addition to a half mirror 8 provided between the objective lens 3 and the imaging lens 4 on 10, a light source 9 for irradiating light to a measurement site of the object 2 through the half mirror 8 is provided. Yes.
A beam splitter 5 that divides the reflected light from the object to be inspected 2 into two is disposed above the imaging lens 4 on the optical axis 10, and the reflected lights 10 </ b> A and 10 </ b> B divided by the beam splitter 5 are arranged. Reflecting mirrors 7A and 7B are provided for sending to the light receiving surfaces 60A and 60B of the CCD cameras 6A and 6B, respectively, which are imaging means.

The visual field areas 102 and 103 (see FIG. 2) of the light receiving surfaces 60A and 60B of the CCD cameras 6A and 6B are less than ¼ of the area of the image (101) captured by the objective lens 3 and the imaging lens 4. In this embodiment, as shown in FIG. 2, the objective lens 3 has a visual field of 4.8 mm × 3.6 mm with a 1/3 inch CCD field of view with a diagonal field of 24 mm.
The center axes 61A and 61B of the light receiving surfaces 60A and 60B of the CCD cameras 6A and 6B are arranged so as not to be coaxial with the optical axes of the reflected lights 10A and 10B divided by the beam splitter 5 (in the figure, the reflected lights 10A and 10B). 10B and arranged so as to be shifted from each other by δ in the horizontal direction.

The CCD camera 6A captures the measurement site and the CCD camera 6B captures the comparison site. The center axis 61B of the light receiving surface of the CCD camera 6B is set to the optical axis of the reflected light 10B by a camera moving means (not shown). The approach or separation is possible.
The camera moving means includes a driving motor 6C, a driving screw (not shown) joined to the output shaft of the driving motor 6C, and a nut (not shown) screwed to the driving screw.

  The drive motor 6C is electrically connected to the control device 81 via a driver 80, and external input means 82 is electrically connected to the control device 81. The drive motor 6C is driven by the external input means 82. Rotates in a predetermined rotation direction (the direction in which the center of the light receiving surface 60B of the CCD camera 6B approaches or separates from the optical axis of the reflected light 10B), and the drive screw connected to the output shaft of the drive motor 6C The CCD camera 6B that is rotated and joined to a nut that is screwed into the drive screw moves in a predetermined direction.

  On the other hand, the CCD camera 6A and the CCD camera 6B are connected to the A / D converters 70A and 70B, the memories 71A and 71B, the comparison processing unit 72 and the determination unit 73, and the image display device 74, respectively. The respective images of the camera 6B are displayed simultaneously on the left and right of the screen of the image display device 74. Then, from the left and right images on this screen, it is possible to confirm whether or not the shooting pattern of the CCD camera 6A matches the shooting pattern of the CCD camera 6B.

  If the shooting pattern of the CCD camera 6A and the shooting pattern of the CCD camera 6B do not match, the driving motor 6C of the CCD camera 6B is driven, and the shooting pattern of the CCD camera 6A matches the shooting pattern of the CCD camera 6B. The operator can move to the position through the external input means while visually confirming the position.

  The camera moving means for the CCD cameras 6A and 6B, the objective lens 3, the half mirror 8, the imaging lens 4, the beam splitter 5, the reflecting mirrors 7A and 7B, and the CCD camera 6B are integrally formed as a base (not shown). The base is movable two-dimensionally in parallel with the surface of the inspection object 2 by a second moving means (not shown), and the objective lens 3 and the inspection object The base is movable in the vertical direction with respect to the object 2 to be inspected by a third moving means (not shown) in order to focus on the 2 parts to be inspected.

Next, the operation of the inspection apparatus configured as described above will be described based on FIG. 3 in addition to FIGS.
First, the device under test is moved above the measurement site of the device under test 2 by the second moving means. Thereafter, the objective lens 3 and the measurement site of the object 2 are focused by the third moving means.
Whether the focus is appropriate or not is determined by the operator based on the video screen on the image display device 74, and is corrected by the third moving means as necessary (step 1).

  Next, the part to be measured of the object to be measured 2 is photographed by the CCD camera 6A through the objective lens 3, and the reference part is photographed by the CCD camera 6B at the same time. The images thus taken are displayed on the screen of the image display device 74 (step 2).

The operator looks at the image from the CCD camera 6A and the image from the CCD camera 6B displayed on the left and right on the screen of the image display device 74, and determines whether or not the patterns of the images match (step). 3) If they do not match, the external input means 82 moves the CCD camera 6B in the left-right direction (direction approaching or moving away from the CCD camera 6A) to match the pattern of each image (step 4).
Since the pattern of the part to be measured has regularity, it is possible to automatically perform the next comparative inspection by registering the contents (CCD position information) taught for each measurement object. Is possible.

In this state, these captured image signals are stored in the memories 71A and 71B via the A / D converters 70A and 70B, and then each data is sent to the comparison processing unit 72 for comparison processing (step 5).
Based on the processed data, the determination unit 73 determines the presence or absence of a defect in the measurement site (step 6), and the result is displayed on the image display device 74 (step 7).
After completion of the inspection (step 8), the inspection object 2 is transported to the next process as necessary.

The configuration relating to the X axis and the Y axis corresponding to the surface to be inspected of the optical inspection apparatus of the present invention is not limited to this embodiment, and the imaging element, the optical system, and the like can be moved in parallel to the inspection surface of the inspection object 2. Any configuration can be used.
The position of the imaging lens 4 may be provided between the reflecting mirrors 7A and 7B and the CCD cameras 6A and 6B facing the reflecting mirrors 7A and 7B.
Further, the lens of the CCD camera may be used as it is without providing the imaging lens 4.

1 is a conceptual diagram of an optical inspection apparatus according to an embodiment of the present invention. It is explanatory drawing which shows the relationship between the area of the light-receiving surface of the imaging means (CCD camera) in the apparatus of the said invention, and the area of the area | region of the to-be-inspected object which an objective lens takes in. It is a flowchart which shows the effect | action of the apparatus of the said invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Inspected object 3 Objective lens 4 Imaging lens 5 Beam splitter 6A CCD camera 6B CCD camera 6C Driving motor 60A Light receiving surface of CCD camera 60B Light receiving surface of CCD camera 61A Center axis of light receiving surface of CCD camera 61B CCD Center axis of light receiving surface of camera 7A Reflector 7B Reflector 70A A / D converter 70B A / D converter 71A Memory 71B Memory 72 Comparison processing unit 73 Determination unit 74 Image display device 8 Half mirror 80 Driver 81 Control device 82 External Input means 9 Light source 10 Optical axis 10A Reflected light 10B Reflected light 101 Image 102 Imaging field area of CCD camera (6A) 103 Imaging field area of CCD camera (6B)

Claims (2)

  An objective lens facing the object to be inspected, an imaging lens disposed on the optical axis of the objective lens, a beam splitter that divides the optical axis of the coupled lens into a plurality of optical axes, and the beam splitter. An inspection device having imaging means respectively disposed on at least two optical axes, wherein the optical distance between the light receiving surface of the imaging means and the object to be inspected is equal to each other, and An optical inspection apparatus, wherein an optical axis of each light receiving surface of the imaging means respectively disposed on the at least two optical axes is not coaxial with the at least two divided optical axes. 2. The optical system according to claim 1, wherein an optical axis of a light receiving surface of the imaging unit is configured to be able to approach and separate from each of the optical axes divided into the at least two optical axes. Inspection device.

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