JPH03248002A - Apparatus for inspecting dimensions of minute material - Google Patents

Abstract

PURPOSE:To improve productivity and to prevent errors in reading by constituting this apparatus of a device comprising a means for supplying a work, an inspecting means and a means for sorting good products and defective products in the vicinity of an index table, a TV camera, and a control device. CONSTITUTION:In a device 34, a work supplying means, an inspecting means, and a means for sorting good products and defective products are provided in the vicinity of an index table. A work 1 is mounted on the device 34. The image of the work 1 is picked up with a TV camera 25. The good products and the defective products are classified with a control part 35 including an image processing device. Namely, an image signal 2 which is received from the camera 25 is outputted into an image processing device 6. In the image processing device, the image signal is binarized based on the preset binarization level. Outer-edge position data 7 are outputted into a computer 8. In the computer, the outer-edge position data which are stored beforehand are compared with the outer-edge position data of the binarized image after the correction of the inclination and the like. The difference is compared with a tolerance value. Thus, the pass/fail judging data are outputted into a classifying part 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for inspecting the dimensions of a workpiece whose outer edge has a complicated shape and requires high dimensional inspection accuracy.

[Conventional technology]

As shown in Fig. 9, in order to inspect with high accuracy the dimensions of the outer edge, warpage δ1, Paris 2, etc. of the workpiece 1, which is a fine object with a long and narrow outer edge having a complicated shape, (Conventional Example 1) Projection (Conventional example 2) A microscopic image is taken with a television camera, and after being binarized by an image processing device, the position data of the outer edge stored in the device storage device in advance and the position data of the outer edge of the binarized image are corrected for tilt and position. There are two methods to compare the two and detect the difference between the two.

Here, the aspect ratio of the work 1 is 4:3 or more, and the longitudinal dimension L1 of the work 1 is the TV camera imaging field of view (usually 8.8 m
The resolution for detecting a workpiece twice as large as the X1 microscope objective (mX 6.6 mm) is equivalent to the cell size of the image pickup tube (usually 11μ chains for solid-state imaging devices), and the resolution of the X1 microscope objective lens (
As an example of an inspection that requires a diameter of about 11 μm (usually around 11 μm),
In order to perform inspection using the image processing method shown in conventional example 2), Xi
It is common to use an objective lens to capture images two or more times.

In addition, as an inspection method, as shown in FIG. 10, the workpiece 1 is placed on a stage 3 equipped with a motor that can automatically position the workpiece 1 in the XY force directions, and inspected with a microscope 6 equipped with an X1 objective lens 4 and a television camera 5. This is described in Precision Measurement Technology published by Sogo Technological Center. (hereinafter referred to as the "XY stage method") and the X1 stage shown in FIG.
A microscope objective lens 7, a reflection mirror 8, and a television camera 9 are used to photograph the left side of the workpiece 1 in the figure, and an objective lens 10, a reflection mirror 11, and a television camera 12 are used to photograph the right side of the workpiece 1 in the figure. This is a method using a two-field lens barrel, in which both images, with the left and right sides having an interval of L2, are combined by an image processing device, and the workpiece 1 can be inspected while being fixed. (hereinafter referred to as "reflector method") Furthermore, the half mirror 1 shown in FIG.
3. X1 TV camera with microscope 14 on the left side in the diagram of workpiece 1, half mirror 15, TV camera with microscope 1
Take a picture of the right side with 6.

There is a method similar to the above-mentioned reflecting mirror method (hereinafter referred to as "half-mirror one-way method").

[Problem that the invention seeks to solve]

(1) The method using a projector has the following problems.

Φ Since the work is done by humans, productivity is low and reading errors are likely to occur.

O Draw an accurate outer edge of workpiece 1 on a transparent film (it is necessary, but even if the line width of the outer edge is about 0.5 mm, the projection magnification is XIO and the projection magnification is 10. The projection magnification is X25 and the same is 0. This results in a measurement error of .02 mm, and the line width becomes the measurement resolution.

The error due to the above line is 0.01■ at a magnification of X50, but even if a large projector with a projection image diameter of 4300 mm is used, the field of view is approximately In order to inspect the workpiece 1, it is necessary to move and inspect the workpiece 1 three or more times. It requires a lot of time to operate and is low in efficiency.

(2) In the case of the "reflector method °", the field of view of the microscope objective lens uses an X lens, so the diameter φ of the objective lens 7 is equal to or larger than the image 1' of the workpiece 1, as shown in Fig. 13. sometimes has the greatest field of vision. Therefore, even if the distance L2 between the objective lenses 7 and 10 shown in FIG. 11 is reduced to the minimum, the first
As shown in FIG. 4, a gap L3 is created between the two television camera imaging fields 18 placed in the microscope field 17, and the vicinity of the center of the workpiece 1 cannot be measured.

(3) “The half-mirror one type” does not have the disadvantage that it cannot measure near the center of the workpiece 1. However, it is difficult to adjust the half-mirrors 13 and 15 shown in Fig. 12, especially when θ
1. TV camera with microscope 14.1 depending on the inclination of θ2
The image reflected in 6 becomes heavy or shifted. An example of the influence of the inclination of θ1 on the image is shown in Figure 15. Using a lens 14' with a diameter of φ that includes the imaging field of view, the objective lens magnification is 11) = 8.8" + 6.6" = 11 mm. Xl, the objective lens resolution is 11 μm, and the wavelength used is 0.55 μm. From the Precision Measurement Technology published by Sogo Technological Center, the aperture angle = 5in-' (numerical aperture) -5in-'0.
03 = 1.75°, and the distance from the center of the lens 14' to the work l, and the distance l to the image sensor 14'' are as follows, so the half mirror that adjusts the resolution equivalent to 11 μm
When the half mirror 13 is provided between the lens 14' and the workpiece 1, the amount of inclination θ1 of the lens 13 is =0.0018''=6
It becomes 1.

It is difficult to adjust the half mirror angle by 6".
``The extent is that the microscope outer cylinder is easily tilted due to thermal deformation, etc., resulting in large measurement errors.

Note that even in the “reflector method” shown in Fig. 11, the mirror 8.1
The measurement error and difficulty of adjustment due to No. 1 are the same.

(4) In the case of "XY stage 2", there are no reflecting mirrors or half mirrors, so there are no drawbacks mentioned in (2) and (3) above. However, when loading and unloading the workpiece, the inspection device must be activated. For example, after the shape of the outer edge is binarized by an image processing device, the data is sent to a computer and stored in a storage device, which records the outer edge position data and the outer edge position of the binarized image. Compare the data after correcting the tilt and position, detect the difference between the two, and compare the difference with the tolerance value to determine pass/fail.Also, stage 3 is moved once and two screens are taken in and inspected.This series of steps Even if the operation is completed in about 2 seconds, it takes at least 2 seconds to remove workpiece 1 from stage 3 shown in No. 1011a, and the same <2 seconds to attach the next workpiece, resulting in a total of 2 seconds.
The inspection equipment cannot be operated for 73 hours. !
Two jigs for installing one workpiece 1 may be provided and shuttled, but since the loading/unloading station also moves at the same time as the stage moves when capturing the workpiece image, the handling mechanism must follow this. A further disadvantage is that this handling device is required on both sides of the inspection section.

[Means for solving problems]

A device for inspecting the dimensions of minute workpieces by image processing includes a means for supplying the workpiece near an index table, a means for inspecting it, a means for sorting good and defective products, and a device that inspects the size of the workpiece in the X direction and Z direction with respect to the workpiece. A television camera with a microscope that can be moved in the direction and outputs the workpiece on the index table as a video signal, and this video signal is converted into a binary image by an image processing device based on the coordinates and inclination between two points of the edge line of the workpiece. This apparatus is characterized in that it comprises a control device capable of determining true dimensions, comparing them with pre-stored workpiece data, detecting the difference between the two, and outputting the output to means for sorting.

〔Example〕

Examples of the present invention will be shown below.

FIG. 1 shows a block diagram of the device. In the apparatus 34, a first station 101 near the index table 21 is provided with a work supply means, a second station 101 is provided with an inspection means, and a third station 103 is provided with a means for sorting good products and defective products.

FIG. 2 shows the work supply means at the first station 101. The parts feeder 19 arranges the workpieces 1 without previously identifying the front and back sides and the front and rear directions. Next, the workpiece 1 is transferred onto a transparent glass plate 22 fixed on an index table 21 using an XY transfer device 20 equipped with a suction batt for vacuum suction. A clamp 23 is provided on the table 21 to hold the work 1 from above only when the table is rotated and to prevent the work 1 from shifting due to centrifugal force.

FIG. 3 shows the inspection means of the second station 102. Illumination of the workpiece 1 is transmitted illumination from a light guide 24 provided under a transparent glass plate 22, which is a transparent body, for example. In order to output a video signal and inspect the workpiece 1, a television camera 25 equipped with an XI microscope is supported by an XZ adjustment stage 26 for adjusting the focus in the Z direction and the position of the camera 25 in the X direction. Below the stage 26, a precision table 27 is provided parallel to the tangent to the index table 21, which is driven by an AC servo motor and a ball screw that performs fine positioning without digital control.

The precision table 27 is used to switch the field of view of the television camera 25 with a microscope from the 28 area to the 28' area shown in FIG.

FIG. 5 shows a means for sorting good products and defective products at the third station 103. An arm 29 with a suction bat that vacuum-chucks the workpiece 1, an AC servo motor 30, and a Z slide 31 that drives the AC servo motor 30 up and down, move the workpiece 1 from the index table 21 to the waste product box 32 or defective product box. 33, position it at a predetermined location, and sort it.

FIG. 6 shows the control device 35 regarding image processing control and discrimination.
The block diagram is shown below. The video signal taken in from the television camera is output to an image processing device.

The image processing device binarizes the pixel image signal based on a preset binarization level and outputs it to the computer as outer edge position data. The computer compares the pre-stored outer edge position data and the outer edge position data of the binarized image after correcting the tilt and position, detects the difference between the two, compares the difference with a tolerance value, and determines whether it is good or bad. The sorting data is output to the department as data for discrimination.

Hereinafter, the width W window wl of the workpiece 1 is determined using the edge lines AL and AR of the hatched part shown in FIG. 7(1) as a reference for inclination.

w2. An example obtained using w3 is shown below. The work l is regulated in the front and rear and left and right directions by the parts feeder 19 shown in FIG.
Even when the index table 21 is rotated, it is pressed by the clamp 23, but a deviation equivalent to the detection resolution of 11 μm occurs.

This discrepancy is unavoidable, so first of all, see Figure 7 (2).
As shown in , the y-coordinate y1 of the outer edge of the window w1 provided at a distance of Xl from the left edge of the screen is determined.

Similarly, y2 is determined using the window w2, and the tilt amount α of the workpiece 1 is determined from the following formula.

2-xl Next, use the window w3 provided at a distance of y3 from the top edge of the screen shown in FIG. Find x4 and find the width Wχ.

W x = x 4- x 3 W x, The true value W of workpiece 1 can be found from α using Wx and the amount of inclination α as shown in Figure 7 (4): W = W
It is found by xXcosα.

FIG. 8 shows the overall structure of this device. The work 1 is placed on the device 34 shown in FIG. 1, and the television camera 2 shown in FIG.
5, an image of the workpiece 1 is taken in, and a control section 35 including an image processing device shown in FIG. 6 sorts the workpieces into good and defective products.

(Effects of the Invention) According to the present invention (1) Since the work is not performed manually using a projector or the like, productivity is improved and reading errors do not occur.

(2) All the coordinates of the outer edge of the workpiece can be obtained using simple trigonometric functions, and there is no need to draw the outer edge shape of the workpiece on a transparent film as in the case of projector work, so errors in the outer edge shape and edge causes will affect the measurement error and resolution. It never becomes.

(3) A resolution corresponding to the projector objective lens magnification X50 can be obtained with the X1 microscope objective lens.

(4) Measurements can also be made near the center of the workpiece at the outer edge of the elongated body.

(5) Withstands workpiece movement, measurement adjustments, and thermal changes, and maintains high accuracy.

[Brief explanation of drawings]

1 to 8 are reference diagrams of the present invention, in which FIG. 1 is a device block diagram, FIG. 2 is a diagram showing a work supply means,
Fig. 3 is a diagram showing the inspection means, Fig. 4 is an explanatory diagram of screen switching, Fig. 5 is a diagram showing the means for sorting good products and defective products, Fig. 6 is a block diagram of the control device, and Fig. 7 is a diagram showing the means for sorting between good and defective products. An explanatory diagram showing an example of workpiece measurement, Fig. 8 is an explanatory diagram showing the overall configuration of the present invention, Fig. 9 is a diagram of the outer edge shape of the workpiece, Fig. 10 is a side view of the conventional "XY stage method", Fig. 11 12 is an explanatory diagram of the conventional "one-side reflective mirror type", FIG. 13 is an explanatory diagram showing the field of view of the objective lens, and FIG. 14 is an explanatory diagram of the conventional one-mirror type. Figure 15 is a diagram showing the field of view of the method, and is an explanatory diagram of how the tilt of a conventional half mirror affects measurement. 1: Workpiece, 21: Index table, 25: Camera, 34: Device, 35: Control, 101: Supply means, 102: Inspection means, 3: Sorting means. 7 Figure 14

Claims (1)

[Claims] 1) A device for inspecting the dimensions of minute workpieces by image processing, which includes a means for supplying the workpiece near an index table, a means for inspecting it, a means for sorting good and defective products, and an X direction with respect to the workpiece. and Z
A television camera with a microscope that can move in different directions and outputs the workpiece on the index table as a video signal,
This video signal is converted into a binary image by an image processing device, and the true dimensions are determined from the coordinates and inclination between two points on the edge line of the workpiece, and compared with pre-stored workpiece data, the difference between the two is detected and sorted. A device for inspecting dimensions of minute objects, characterized by comprising a control device capable of outputting data to a means.