JPH05296739A - Contour form measuring device - Google Patents

Abstract

PURPOSE:To secure a contour form measuring device that can measure the contour form of a measured work so accurately in a simple system. CONSTITUTION:A scale surface 16b is formed in the underside of a work table 16. ACCD camera 34 of low resolution, photographing the whole body of this work table 16 is installed there. Another CCD camera 36 of high resolution, photographing a part of a projected image 53 is installed in a mobile table 28. Then, a key mark 20A is selected out of a photographed image 50 taken by the CCD camera 36 by a controller 48, and a relative coordinate at a contour measuring point used with this key mark 20A as the reference is calculated. A scale coordinate in the work table 16 of the key mark 20A is calculated out of the photographed image 53 of the whole work table 16 photographed by the CCD camera 34, and on the basis of the scale coordinate of the key mark 20A and the relative coordinate of the calculated measuring point, the picture element resolution of the CCD camera 36 is applied to the relative coordinate, and thereby this relative coordinate is converted into the scale coordinate at a hare position 0 of the work table 16. Plural converted scale coordinates are coupled together, through which such sequence control as forming the contour form of a measured work 18 is carried out.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contour shape measuring apparatus, and more particularly to a contour shape measuring apparatus for measuring the contour shape of small parts such as small gears which cannot be measured by a contact type contour shape measuring apparatus.

[0002]

2. Description of the Related Art Recently, as a contour shape measuring apparatus of this type, an object to be measured is imaged by a fixedly mounted CCD camera,
It has been proposed to measure the contour shape of an object to be measured by converting this image into an electric signal and performing image processing measurement. However, the contour shape measuring device having a fixed CCD camera is subject to the restriction due to the photographing magnification of the CCD camera, and therefore has the drawbacks described below.

That is, if the photographing magnification is lowered in order to pick up the image of the entire object to be measured, the pixel resolution is lowered, so that the contour shape cannot be measured with high accuracy. If the photographing magnification is increased and the resolution is increased to obtain high accuracy, only a part of the object to be measured can be imaged and the contour shape of the entire object to be measured cannot be measured. Therefore, in order to eliminate such problems, a CCD camera with a high photographing magnification is used, and this CC
Either the D camera or the work table on which the object to be measured is placed is sent with high precision (that is, sent without causing an error in the feed amount), and the measured value is obtained from the feed amount and the high-precision image processing result. I have to. As a result, the contour shape of the entire object to be measured can be measured with high accuracy.

[0004]

However, the CCD
The conventional contour shape measuring apparatus that sends either one of the camera and the work table with high accuracy has a drawback that a moving system for sending the CCD camera or the work table with high accuracy becomes very complicated and the cost becomes enormous. is there.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a contour shape measuring apparatus capable of measuring the contour shape of an object to be measured with high accuracy by a simple system.

[0006]

According to the present invention, in order to achieve the above object, an object to be measured is placed on the upper surface and a plurality of marks indicating positions from the origin are formed on the surface at predetermined intervals. A work table, a movable table that is disposed so as to face the work table and is movable in at least the same plane, and is mounted on the work table at an imaging magnification including at least one of the marks. A first camera for capturing an image of a part of the measured object placed, and means for calculating the position of the contour of the measured object based on the mark in the captured image based on the output from the first camera, Means for calculating the position of the contour with respect to the origin from the position of the reference mark from the origin and the position of the calculated contour;
And moving the moving table to measure the contour shape of the entire object to be measured.

[0007]

According to the present invention, a part of the object to be measured is imaged by the first camera having a photographing magnification including at least one of the marks formed on the work table. Then, based on the output from the first camera, the relative position of the contour of the DUT based on the mark in the captured image is calculated, and the position of the reference mark from the origin and the calculated contour. Then, the absolute position of the contour with respect to the origin is calculated. As a result, the contour shape of the measured object in the captured image is measured, and when measuring the contour shape of the entire measured object, the first camera is moved in a plane on the moving table to measure the entire measured object. Is divided into a plurality of blocks and imaged, and the above-described image processing is performed for each block. As a result, the contour shape of the entire measured object can be measured with high accuracy without being affected by the feed amount error of the moving table.

Further, the mark in the picked-up image picked up by the first camera is identified based on the output from the second camera having a photographing magnification capable of picking up the image of the entire work table. Furthermore,
The work table is a transparent plate, the mark is attached toward the first camera side, and the mark forming surface and the object mounting surface are separated by the thickness of the work table. It is possible to separately and clearly capture the image of the measured object and the mark. That is, when the object to be measured is imaged, the first camera is moved in a predetermined direction on the moving table so as to focus on the object to be measured. As a result, the image of the mark is blurred and only the object to be measured can be clearly imaged. On the other hand, when capturing the image of the mark, the first camera is moved in the other direction by a predetermined amount so as to focus on the mark. As a result, the object to be measured is imaged out of focus, and only the mark can be clearly imaged. Therefore, even if a part of the object to be measured is hidden by the mark, that part can also be imaged, so that the contour shape of the entire object to be measured can be accurately measured.

Further, if an illuminating means for irradiating the mark from below is provided, the mark can be more clearly imaged.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of a contour shape measuring apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a contour shape measuring apparatus 10 according to the present invention. A work table 16 is horizontally attached to an opening 14 formed in a support 12 of the contour shape measuring apparatus 10.

The work table 16 is formed of a transparent plate, and an object 18 to be measured such as a small gear is placed on the upper surface 16a thereof. Further, on the lower surface 16b of the work table 16, as shown in FIG. 2, cross-shaped marks 20, 20, ...
, And dot marks 22, 22 ... Are formed vertically and horizontally at predetermined intervals. The marks 20, 20 ... Are formed at intervals of 1 mm, and the marks 22, 22 ... Are formed in the middle thereof. Further, reference numerals indicating XY coordinates are attached to the upper edge portion and the left edge portion of the marks 20, 20 ... In the figure.

Above the work table 16, background illuminations 24, 24 are arranged as shown in FIG. In addition, the light scattering plate 26 is used for the background lighting 24, 24 and the work table 16.
The light-scattering plate 26 is provided between the background illuminations 24 and 24 and can change the traveling direction of the light emitted from the background illuminations 24, 24 to the direction of the work table 16. The work table 16
As shown in FIG. 3, a moving table 28 that can move in the three-dimensional XYZ directions is installed below the table. The moving table 28 is moved in the X direction by driving the ball screw device 30, is moved in the Y direction by driving the ball screw device 32, and is moved in the Z direction by driving an elevating device (not shown). Be moved.

A CCD camera 34 is attached to the moving table 28. A macro lens is attached to the CCD camera 34, and the entire work table 16 can be imaged by this macro lens. Incidentally, CCD
A light 35 is attached to the tip of the camera 34. A CCD camera 36 is attached to the moving table 28 adjacent to the CCD camera 34. CC
A high-magnification objective lens 38 is attached to the D camera 36, and the DUT 1 projected through the work table 16 is measured.
It is possible to capture an image of a part of 8 and the marks 20, 22 in the image of the part. The CCD camera 36 is integrally provided with a light 40, and the light from the light 40 is emitted toward the lower surface 16a of the work table 16 via the polarizing glass 42.

The CCD cameras 34 and 36 are connected to a controller 48 via cables 44 and 46, respectively. This controller 48 includes CCD cameras 34, 3
Image processing measurement is performed based on the information from 6 and sequence control for creating the contour shape of the DUT 18 is performed. Next, the contour shape measuring apparatus 10 configured as described above
The sequence control by the controller 48 will be described.

The sequence control by the controller 48 will be described below. One mark (key mark) 2 of the marks 20 and 22 formed on the work table 16 from the captured image 50 (FIGS. 4 and 5) in the narrow field of view captured by the CCD camera 36.
Select 0A. Arbitrary measurement points a, b, c, d, e, f in the captured image 50 based on the selected key mark 20A.
The relative coordinates of g (FIG. 5) are calculated.

Scale coordinates (absolute coordinates) (x, y) of the key mark 20A at the origin 0 of the work table 16.
From the captured image 52 (FIG. 4) of the entire work table 16 captured by the CCD camera 34. The scale coordinates of the key mark 20A are (0.5, 1.5). Scale coordinates of the key mark 20A (0.5, 1.5)
Based on the calculated relative coordinates of the plurality of measurement points, the relative coordinates of each measurement point are multiplied by the pixel resolution of the CCD camera 36, and each relative coordinate is scaled coordinates (x, y) at the origin 0 of the work table 16, (X, y) ...

A plurality of scale coordinates (absolute coordinates) (x, y), (x, y) ... Thereby, the contour shape of the DUT 18 in the captured image 50 (FIG. 4) can be measured. Then, when measuring the contour shape of the entire object to be measured 18, the CCD camera 36 is planarly moved by the moving table 28, and the entire captured image 53 (FIG. 4) is divided into a plurality of blocks 54, 54, ... To do. Then, for each of the blocks 54, the sequence control of the above-mentioned (1) is performed. As a result, the contour shape of the entire measured object 18 can be measured with high accuracy without being affected by the feed amount error of the moving table 28.

In the present embodiment, the scale surface (lower surface) 16b of the work 16 is covered with the CCD cameras 34, 36.
Mounted toward the side, the scale surface 16b and the DUT 1
Since the mounting surface (upper surface) 16a of 8 is separated by the thickness of the work table 16, the image pickup 53 of the object to be measured 18 and the marks 20 and 22 imaged by the CCD camera 36 are separately and respectively. A clear image can be taken.

That is, when the object to be measured 18 is imaged, the CCD camera 36 is raised by a predetermined amount by the moving table 28 so as to focus on the object to be measured 18. As a result, the marks 20 and 22 are imaged out of focus, so that only the object to be measured 18 can be clearly imaged. On the other hand, when the marks 20 and 22 are imaged, the CCD camera 36 is lowered by a predetermined amount so as to focus on the marks 20 and 22. As a result, the object to be measured 18 is imaged out of focus, and only the marks 20 and 22 can be clearly imaged. Therefore, a part of the object to be measured 18 hidden by the mark 20B (FIG. 5) can be imaged, and the contour shape of the entire object to be measured 18 can be accurately measured.

Since the CCD camera 36 is provided with the light 40 for irradiating the scale surface 16b from below, the marks 20, 22 can be more clearly imaged. Further, the present embodiment has the following effects. First,
By attaching the scale surface 16b toward the CCD cameras 34, 36 side, it is possible to prevent the marks 20, 22 from being worn due to contact with the object to be measured 18.

Secondly, the measurement accuracy depends only on the accuracy of the image processing measurement of the controller 48 and the accuracy of the scale itself, not the feed accuracy of the moving table 28.
No change over time or over time. Thirdly, since the work table 16 is fixed and the camera is moved, the object to be measured 18 can be easily transported and fixed.

Fourth, the marks 20, 22 on the scale image
It is possible to correct the magnification and distortion of the optical system and the video signal system by measuring the interval and distortion of the grid of the. Further, although the CCD cameras 34 and 36 are used in the present embodiment, the present invention is not limited to this, and other solid-state imaging devices capable of converting an image into an electric signal and outputting the electric signal, a video camera, a TV camera, a microscope, or the like. good.

[0023]

As described above, according to the contour shape measuring apparatus of the present invention, the first camera images a part of the object to be measured including at least one of the marks formed on the work table, Based on the output from the first camera, the position of the contour of the object to be measured with reference to the mark in the captured image is calculated, and the position of the reference mark from the origin and the position of the calculated contour are calculated. The position of the contour portion from the origin is calculated. Thereby, the contour shape of the measured object in the captured image can be measured. Further, when measuring the contour shape of the entire object to be measured, the first camera is moved in a plane on the moving table, the entire object to be measured is divided into a plurality of blocks, and an image is taken for each block. Perform processing.
As a result, the contour shape of the entire measured object can be measured with high accuracy without being affected by the feed amount error of the moving table.

If a second camera having a photographing magnification capable of picking up the entire work table is provided, the mark in the picked-up image picked up by the first camera is based on the output from the second camera. It is possible to identify the position of the mark among the plurality of marks. Further, by attaching the mark of the work toward the first camera side, and separating the surface of the mark and the mounting surface of the measured object by the thickness of the work table,
The image of the object to be measured and the mark captured by the first camera can be captured separately and clearly.

Further, if an illuminating means for illuminating the mark from below is provided, the mark can be more clearly imaged.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a contour shape measuring apparatus according to the present invention.

FIG. 2 is an explanatory diagram of a work table applied to the contour shape measuring apparatus according to the present invention.

FIG. 3 is a perspective view showing an embodiment of a contour shape measuring apparatus according to the present invention.

FIG. 4 is a part of a picked-up image picked up by a low-resolution CCD camera applied to a contour shape measuring apparatus according to the present invention.

FIG. 5 is a captured image captured by a high resolution CCD camera applied to the contour shape measuring apparatus according to the present invention.

[Explanation of symbols]

 10 ... Contour measuring device 16 ... Work table 20, 22 ... Mark 20A ... Key mark 24 ... Background illumination 26 ... Light scattering plate 28 ... Moving table 34, 36 ... CCD camera 48 ... Controller

Claims (4)

[Claims] 1. A work table on which an object to be measured is placed, and a plurality of marks indicating positions from the origin are formed at a predetermined interval on the surface of the work table. A movable table that is movable in the same plane; a first camera that is installed on the movable table and that captures an image of a portion of the object to be measured placed on the work table at an imaging magnification that includes at least one of the marks; Means for calculating the position of the contour of the measured object based on the mark in the captured image based on the output from the first camera, and the position of the reference mark from the origin and the calculated contour. Means for calculating the position of the contour from the position based on the origin, and the contour shape measuring apparatus for moving the moving table to measure the contour shape of the entire object to be measured. 2. The mark in the picked-up image is identified at which position among the plurality of marks based on an output from a second camera capable of picking up an image of the entire work table. The contour shape measuring apparatus according to claim 1. 3. The work table is formed of a transparent plate, and the mark is attached toward the first camera, and the first camera measures the object to be measured when the object is imaged. A predetermined amount is moved by the moving table so that the mark is focused on, and when the mark on the work table is imaged, a predetermined amount is moved in another direction so that the mark is focused. 1. The contour shape measuring device according to 1. 4. The contour shape measuring apparatus according to claim 3, further comprising illumination means for illuminating the mark of the work table from below when the first CCD camera images the mark on the work table. ..