JPH06207809A - Microscopic hole dimension measuring apparatus - Google Patents

Abstract

PURPOSE:To enable precise measurement of dimensions of a microscopic hole automatically by performing an automatic control the focus, a quantity of illumination light and an opening stop of a microscope according to the diameter of a hole to be measured to process an transmission magnified image taken. CONSTITUTION:A relationship between the optimum quantity of light of a lighting device 11 and a lighting opening stop 12 determined from a plurality of reference dies with varied dimensions and the diameter of holes of reference dies and a linear diameter drawn actually with the reference dies is stored 53 into a system controller 5. In the actual measurement, drawing dies 15 to be measured is placed on a table 14 of a microscope 1 and a focus adjusting section 19 is controlled automatically based on a data of a focus detecting section 21 in a CCD camera 3 by the control of a focus control section 21 and then, prescribed linear diameter values of the dies 15 are inputted. When a need arises for changing the magnification of the microscope 1 depending on the hole diameter, a lens is switched to the one corresponding to the hole diameter. Thus, the quantity of illumination light and the stop 12 of the device 11 are controlled 23 and 24 automatically to be set to the optimum conditions based on the table in the device thereby obtaining the diameter of the dies by an image processing 4 from a transmission magnified image taken.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine hole size measuring device for automatically and precisely measuring the hole diameter and slit width of an object to be measured having a fine hole such as a drawing die by using a microscope for obtaining a transmission enlarged image. Regarding

[0002]

2. Description of the Related Art The hole diameter of a wire drawing die is 0.01-2.
It has a small value of 0 mm. It is difficult to accurately measure the diameter of such a minute hole using a conventional measuring device. Also in the JIS standard, the hole diameter of the wire drawing die is determined by the measured value of the drawn wire diameter. However, there is a demand for the user to construct a system that directly and precisely measures the hole diameter of the wire drawing die and predicts the wire diameter to be completed by this.

[0003]

In a measuring device using a microscope, focusing and adjustment of a transillumination aperture stop are performed as follows.
This is an important factor for accurate measurement. However, conventionally, even if the focusing is automated, there is no automated aperture stop. The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a micropore size measuring apparatus that automatically and precisely measures the micropore size using a transmission magnified image by a microscope.

[0004]

A micropore size measuring device according to the present invention comprises a microscope for obtaining a transmission magnified image of an object to be measured having micropores, and an image pickup device for picking up a magnified image of this microscope.
Image processing means for digitizing the output signal of the image pickup device to detect the edge coordinates to calculate the size of the minute hole, microscope control means for automatically adjusting the light quantity of the illumination light of the microscope and the illumination aperture stop, and measuring. It has a storage device for storing the optimum value of the light quantity of the illumination light of the microscope suitable for the power hole size and the numerical aperture of the illumination aperture stop, and based on the storage device by inputting the standard value of the hole size to be measured. And a system control unit for optimally controlling the microscope control unit.

The micropore size measuring device according to the invention also comprises
When the object to be measured is a drawing die, the system control means is characterized in that it has an arithmetic unit for predicting the wire diameter of the fiber obtained by the drawing die based on the hole diameter obtained by the image processing means. .

[0006]

According to the present invention, it is possible to measure the micropore size of the object to be measured by picking up a transmission magnified image of the microscope and processing the image. Further, in the present invention, the focus of the microscope,
The amount of illumination light and the illumination aperture stop are automatically controlled according to the hole diameter to be measured, which enables highly accurate hole size measurement. Further, by using the hole size measuring device of the present invention, it is possible to easily construct a system for predicting the wire diameter to be completed by the wire drawing die.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of a wire drawing die hole diameter measuring apparatus according to an embodiment of the present invention. FIG. 2 shows the structure of the drawing die to be measured. As shown in FIG. 1, this device is attached to an optical microscope 1 for obtaining a transmission enlarged image of a drawing die 15 placed on a table 14, a microscope control device 2 for automatically adjusting the focus of the microscope 1 and the like. CCD
It has a camera 3, an image processing device 4 for processing the output signal of the CCD camera 3, and a system control device 5 such as a computer for controlling the microscope control device 2. The system control device 5 has a function of predicting the wire diameter based on the hole diameter data obtained by the image processing device 4, in addition to the control of the microscope control device 2.

An image obtained by the CCD camera 3, hole diameter data of a drawing die obtained by image processing the image,
Further, a display 5 and a printer 6 are provided to output and display the wire diameter data predicted based on the hole diameter.

The microscope 1 is for obtaining a transmission enlarged image of the drawing die 15 placed on the table 14 by the illumination device 11. The illumination light amount of the illumination device 11 and the aperture driving unit 13 of the aperture stop 12 are automatically controlled by the light amount control unit 24 and the aperture control unit 23 in the microscope control device 2, respectively. The objective lens 16 of the microscope 1 is a lens mount 1
The lens switching device 18 attached to the lens 7 is controlled by the lens exchange control unit 22 in the microscope control device 2. Of course, the objective lens 16 can be manually switched. The focus adjustment unit 19 of the microscope 1 is also automatically controlled by the focus control unit 21 in the microscope control device 2.
The focus control unit 21 takes in focus detection data from the focus detection unit 21 in the CCD camera 21, and performs optimum control of the focus based on this data.

Lens exchange controller 2 in microscope controller 2
2, control data is sent from the system controller 5 to the aperture controller 23 and the light amount controller 24. The system control device 5 includes a CPU 51, an arithmetic circuit 52, and a storage circuit 53. In addition to various system control data, the storage circuit 53 stores the hole diameter (wire diameter) of the drawing die to be measured, and the optimum value of the light quantity of the illumination light of the microscope 1 and the numerical aperture (NA) of the illumination aperture stop for this. It has a table that stores the previously determined correlations between. Then, by inputting the standard value of the hole diameter of the wire drawing die to be measured from an input device such as a keyboard, an optimum control signal is sent to the microscope control device 2 based on the data in the storage table.

The image processing device 4 includes an A / D converter 41 for digitizing an output signal of the CCD camera 3, a frame memory 42 for storing the obtained digital data, and a slice of the data in the frame memory 42 at a predetermined slice level. And binarizing circuit 43 for binarizing, edge coordinate detecting circuit 44 for detecting edge coordinates from the binarized data, and arithmetic circuit 45 for calculating the hole diameter of the drawing die from the detected edge coordinate data. Has been done.

The hole diameter of the wire drawing die obtained by the image processing device 4 is sent to the system control device 5, and the arithmetic circuit 5 is operated.
In step 2, an operation for obtaining the wire diameter of the fiber drawn by the wire drawing die is performed. The relation between the hole diameter of the wire drawing die and the wire diameter is measured in advance and stored in the memory circuit 52, and the arithmetic circuit 52 predicts the wire diameter based on the relational expression.

The specific operation of die diameter measurement and wire diameter prediction by the system of this embodiment will be described below. First of all, it is necessary to pre-set the system prior to the main measurement. First, automatic focusing is performed using a reference die whose hole diameter is known. The focus control unit 21 in the microscope control device 2 is operated by the command switch, and the focus adjustment unit 19 is automatically controlled based on the data of the focus detection unit 21 in the CCD camera 3. Incidentally, FIG. 3 shows data obtained by measuring the relationship between the focus position shift and the die diameter measurement error for a 1.95 mmφ wire drawing die. It is understood from this data that accurate focusing is important for high precision measurements.

Next, the light amount of the illumination device 11 of the microscope 1 and the aperture stop 12 are manually adjusted to select the optimum light amount and the aperture stop. Depending on the conditions of the aperture stop, the brightness distribution of the optical image corresponding to the die hole obtained by the microscope 1 changes as shown in FIGS. 4 (a) to 4 (c). When these optical image pickup signals are digitized and the distribution of bright and dark pixel numbers is obtained,
Corresponding to FIGS. 4 (a)-(c), the distributions are as shown in FIGS. 5 (a)-(c), respectively. Assuming that the slice level of the data binarization by the image processing device 4 is set to 1/2 of the bright and dark parts of the image, the boundary between the bright and dark parts is steep as shown in FIG. It is preferable to set the aperture stop so that the bright portion is as flat as possible. The optimum conditions for the aperture stop of the illumination also differ depending on the diameter of the die to be measured. The data is shown in FIG. Since the relationship between the NA of the aperture stop and the die diameter measurement error differs depending on the die diameter as shown in the figure, it is necessary to select the optimum NA (circle in FIG. 6) that minimizes the measurement error according to the die diameter. .

Therefore, in the preliminary setting, it is necessary to use a plurality of reference dies having different known dice diameters to obtain the optimum light amount and the optimum NA of the illumination aperture stop. All the data of the correlation between the hole diameter and the optimum light amount and the optimum aperture diaphragm thus obtained are stored as a table in the storage circuit 53 in the system control device 5.

In the preliminary setting of the system, the relation between the hole diameter of the reference die and the wire diameter when the wire is actually drawn by the reference die is obtained by a plurality of measurements and an averaging process using the least squares method. This is written and stored in the storage circuit 53 in the system control device 5. Specifically, the relationship between the die diameter and the wire diameter is as shown in FIG. 7, for example. By obtaining and storing this relational expression in advance, when the diameter of the drawing die is actually measured based on this, the calculation circuit 52 can calculate and output the predicted wire diameter.

After the above preliminary setting is completed, the main measurement is started. When the drawing die to be measured is installed on the table of the microscope and the focusing command switch is pressed, the focus control unit 2 in the microscope control device 2 is operated as in the case of the above-mentioned preliminary setting.
1 operates to automatically control the focus adjustment unit 19 based on the data of the focus detection unit 21 in the CCD camera 3. If necessary at this time, the operator manually adjusts the hole of the drawing die so that it is located in the center of the camera. After adjusting the position, key in the standard wire diameter of the wire drawing die to be measured next. When it is necessary to change the magnification of the microscope depending on the hole diameter,
Key in the lens switching signal (lens designation data) corresponding to the hole diameter. Accordingly, based on the table in the system control device 5, the illumination light amount of the illumination device 11 and the diaphragm drive unit 13 of the aperture stop 12 are automatically controlled by the light amount control unit 24 and the aperture control unit 23 in the microscope control device 2, respectively. Is set to optimal conditions.

When a measurement start command is issued, the optical image is digitally processed by the image processing device 4 to obtain the die diameter, and the predicted wire diameter is calculated in the system controller 5 based on the die diameter. . For example, display 5
On the top, the obtained die diameter and the predicted wire diameter are output and displayed together with the standard value of the wire diameter keyed in. Further, these data are printed out by the printer 6 as needed.

In the embodiment, the case where the minute holes are circular holes of the drawing die has been described, but the present invention is not limited to this, and the same applies when the minute holes are slits and the slit width is measured. The present invention can be applied to.

[0020]

As described above, according to the present invention, it is possible to automatically measure the micropore size of the object to be measured by picking up a transmission magnified image of a microscope and performing image processing. Further, in the present invention, the light quantity of the illumination light and the illumination aperture stop are automatically controlled according to the hole diameter to be measured, which allows highly accurate hole size measurement.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a structure of a drawing die to be measured.

FIG. 3 is a diagram showing a relationship between a die diameter measurement error and defocus.

FIG. 4 is a diagram showing a relationship between a brightness distribution of an optical image and an illumination aperture stop.

5 is a diagram showing a digitized pixel number distribution corresponding to the brightness distribution of FIG.

FIG. 6 is a diagram showing a relationship between a die diameter measurement error and an illumination aperture stop.

FIG. 7 is a diagram showing a relationship between a die diameter and a wire diameter of a fiber drawn by the die.

[Explanation of symbols]

1 ... microscope, 2 ... microscope control device, 3 ... CCD camera,
4 ... Image processing device, 5 ... System control device, 5 ... Display, 6 ... Printer.

Claims (2)

[Claims] 1. A microscope for obtaining a transmission magnified image of an object to be measured having fine holes, an image pickup device for picking up a transmission magnified image of this microscope, and an output signal of this image pickup device being digitized to perform edge coordinate detection, Image processing means for calculating the size of the minute hole, microscope control means for automatically adjusting the light amount of the illumination light of the microscope and the illumination aperture stop, and the light amount of the illumination light of the microscope and the illumination aperture stop suitable for the hole size to be measured. And a system control means for optimally controlling the microscope control means on the basis of the storage device by inputting a standard value of a hole size to be measured. A micropore size measuring device characterized by. 2. The object to be measured is a wire drawing die,
2. The micropore size measuring device according to claim 1, wherein the system control means has an arithmetic unit that predicts a wire diameter of a fiber obtained by the drawing die based on the hole diameter obtained by the image processing means. .