JP6095486B2 - Image measuring device - Google Patents

Description

  The present invention relates to an image measurement apparatus that measures a measurement object three-dimensionally by imaging the measurement object.

  Examples of an image measuring device that three-dimensionally measures a measurement target based on image information acquired by an imaging device include a device that uses white light having a wide spectrum width and a device that uses contrast information. Such an image measuring apparatus measures the three-dimensional shape of the object to be measured from image information obtained at each vertical position by scanning the imaging apparatus in a direction perpendicular to the stage. In such an image measuring apparatus, for example, when the size of the object to be measured does not fit in one field of view of the imaging apparatus, the imaging apparatus is moved with respect to the stage, and the measurement results at each measurement position are acquired and then combined. The so-called stitching method is sometimes used (Patent Document 1).

JP 2012-112705 A

  However, in such an image measuring apparatus, the scanning range in the vertical direction is fixed to a predetermined range at each measurement position, so that scanning takes time and is inefficient.

  The present invention has been made in view of these points, and an object thereof is to provide an image measurement apparatus capable of efficiently measuring a wide measurement range.

  An image measurement apparatus according to the present invention is provided with a stage on which a measurement object is placed, and a relative imaging device that can move relative to the stage. The measurement object is imaged in a predetermined imaging range that is narrower than the measurement range. A position control device that moves the image pickup device to a plurality of measurement positions within the measurement range, and scans in the direction perpendicular to the stage at each measurement position, and scanning of the image pickup device. An arithmetic processing unit that calculates a displacement in the scanning direction at each measurement position based on the obtained image information of the predetermined imaging range at each measurement position. The imaging device is configured to be able to image a preliminary measurement range wider than the predetermined imaging range prior to the main measurement for measuring the displacement in the scanning direction at each measurement position. The arithmetic processing unit preliminarily measures a displacement in a general scanning direction at each measurement position from image information obtained by scanning the imaging device in the preliminary measurement range during the preliminary measurement. Based on the result, the scanning range of the imaging device at each measurement position at the time of the main measurement is set.

  That is, the image measuring apparatus according to the present invention sets the scanning range at each measurement position at the time of the main measurement based on the approximate displacement in the scanning direction at each measurement position of the wide range of preliminary measurement range acquired in advance by preliminary measurement. Therefore, the length of the scanning range at the time of the main measurement can be shortened, and the measurement efficiency can be improved.

  According to the present invention, it is possible to provide an image measurement apparatus capable of efficiently measuring a wide measurement range.

1 is an overall view of an image measuring device according to a first embodiment of the present invention. It is a block diagram which shows the structure of the same apparatus. It is a flowchart explaining operation | movement of the apparatus. It is the schematic for demonstrating operation | movement of the apparatus. It is the schematic for demonstrating operation | movement of the apparatus. It is the schematic for demonstrating operation | movement of the conventional image measuring apparatus.

[Configuration of Image Measuring Apparatus According to First Embodiment]
Next, the configuration of the image measurement apparatus according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an overall view of an image measuring apparatus according to the present embodiment.

  The image measuring device 10 is an image measuring device 10 in which cameras 17a and 17b are mounted as image pickup devices for picking up the workpiece 12, and the image measuring device 10 is electrically connected to the image measuring device 10 and stored in a program stored therein. And a computer (hereinafter referred to as “PC”) 20 for controlling the driving of the computer.

  The image measuring machine 10 is configured as follows. That is, a stage 13 for mounting a workpiece 12 (measurement object) is mounted on the gantry 11, and this stage 13 is parallel to the upper surface of the stage 13 by a Y-axis drive mechanism 18. Driven by. Support arms 14 and 15 extending upward are fixed to the center of both side edges of the gantry 11, and an X-axis guide 16 is fixed so as to connect both upper ends of the support arms 14 and 15. An imaging unit 17 that images the workpiece 12 is supported by the X-axis guide 16. The imaging unit 17 is configured to be driven along the X-axis guide 16 in the X-axis direction parallel to the upper surface of the stage 13 and perpendicular to the Y-axis direction by the X-axis drive mechanism 16a. In addition, the imaging unit 17 can image the first imaging device 17a having a predetermined imaging range used during the main measurement as a measurement visual field, and the entire measurement range that is used during the preliminary measurement and wider than the measurement visual field for the main measurement. A second imaging device 17b. These imaging devices 17a and 17b are configured to be switchable between preliminary measurement and actual measurement. These imaging devices 17a and 17b may be configured as one camera by adjusting the magnification of the objective lens. The imaging unit 17 is configured to be movable in the Z-axis direction orthogonal to the upper surface of the stage 13 by the Z-axis drive mechanism 17c. As described above, the X-axis drive mechanism 16a, the Y-axis drive mechanism 18, and the Z-axis drive mechanism 17c are positions that drive the imaging unit 17 relative to the stage 13 in the X, Y, and Z axis directions orthogonal to each other. The control device is configured.

  The image measuring device 10 according to the present embodiment performs imaging in the XY directions of the cameras 17a and 17b by moving the cameras 17a and 17b in the XY directions with respect to the upper surface of the stage 13 and scanning in the Z-axis direction. The displacement (Z value) in the Z-axis direction at each measurement position of the workpiece 12 is detected from the position information and the contrast information of each minute range of the image obtained at that position. The displacement in the Z-axis direction can be detected by a white interferometer in addition to detecting from such contrast information. The white interferometer, for example, guides white light having a wideband spectrum to the work 12 and the reference surface, interferes with each reflected light, acquires a position where the peak value of the interference signal for each pixel is observed, and obtains a peak for each pixel. The displacement of the workpiece 12 in the Z-axis direction is detected according to the position and the position of the reference plate constituting the reference surface.

  The computer 20 includes a computer main body 21, a keyboard 22, a joystick box (J / S) 23, a mouse 24, a display 25, and a printer 26. The computer main body 21 is configured, for example, as shown in FIG. That is, the image information of the workpiece 12 input from the imaging unit 17 is stored in the image memory 32 via the interface (I / F) 31.

  The CAD data of the work 12 is input to the CPU 35 via the I / F 33, subjected to predetermined processing by the CPU 35, and stored in the image memory 32. The image information stored in the image memory 32 is displayed on the display 25 via the display control unit 36.

  On the other hand, code information and position information input from the keyboard 22, J / S 23, and mouse 24 are input to the CPU 35 via the I / F 34. The CPU 35 executes various processes according to the macro program stored in the ROM 37 and the program stored in the RAM 40 from the HDD 38 via the I / F 39.

  The CPU 35 controls the image measuring device 10 via the I / F 41 according to the program. The HDD 38 is a recording medium for storing various data. The RAM 40 provides a work area for various processes.

[Operation of Conventional Image Measuring Apparatus]
Next, prior to description of an image measurement method using the image measurement apparatus according to the present embodiment, a conventional image measurement method will be described. FIG. 6 is a schematic diagram for explaining a conventional image measurement method.

  As shown in FIG. 6, when measuring the three-dimensional shape of the measurement range IR0 wider than the imaging range IR1 of the camera 17a, the camera 17a is parallel to the upper surface of the table 13 as in the measurement positions P1, P2,. .., P9, the camera 17a is scanned in the Z-axis direction orthogonal to the upper surface of the table 13, and the workpiece 12 at each measurement position P1, P2,. The displacement in the Z-axis direction (Z value) is detected. More specifically, for example, the Z value of each minute part is obtained from the contrast information of each minute part in the imaging range IR1 of the camera 17a. In the conventional image measurement method, since the scan range SR1 in the Z-axis direction at each measurement position P1, P2,..., P9 is the same, the scan range includes the lowest position to the highest position of the workpiece 12. It was necessary to set SR1. For this reason, the entire scanning range is long, scanning takes time, and it is inefficient.

[Operation of Image Measuring Device According to this Embodiment]
Next, a measurement method of the image measurement apparatus according to this embodiment will be described. FIG. 3 is a flowchart for explaining an image measuring method using the image measuring apparatus according to the present embodiment.

  In step S11, as shown in FIG. 4, as a preliminary measurement, a preliminary measurement using a second camera 17b having a wider field of view than the first camera 17a and preferably capable of imaging the entire measurement range IR0 is performed. Perform autofocus. Hereinafter, autofocus performed over a wide range by preliminary measurement is referred to as multipoint autofocus. In multipoint autofocus, a two-dimensional image at each position in the Z-axis direction is acquired as preliminary measurement image information for the measurement range IR0 while scanning the second camera 17b in the scan range SR0 in the Z-axis direction. And the displacement (Z value) of the Z-axis direction in each measurement point P1-P9 is detected from the acquired preliminary measurement image information. Here, the preliminary measurement range does not necessarily coincide with the entire measurement range IRO, and can be set as necessary within a narrower range, for example.

  In addition, since the multipoint autofocus in step S11 only needs to obtain a rough Z value, the frame rate of the second camera 17b is set lower than the frame rate of the first camera 17a, etc. It is also possible to carry out with low accuracy compared with this measurement. Therefore, even when the scan range SR0 is set to the same length as the conventional one, it is possible to scan faster than the conventional one.

  In step S12, the scan range SR1 in the Z-axis direction of the first camera 17a for the main measurement is calculated from the Z values of the measurement positions P1 to P9 in the preliminary measurement of the measurement range IR0 acquired in step S11. The scan range SR1 of the main measurement can be set with the Z value of each measurement position P1 to P9 as the center, the start point, or the end point. For example, as shown in FIG. 5, when the measurement range IR0 is divided by a 3 × 3 imaging range IR1 in the XY axis direction and each imaging range IR1 is set as the main measurement range of each measurement position P1 to P9, each measurement position P1 to P1 is measured. The scan range SR1 in the Z-axis direction at P9 is a range starting from the Z values (measurement positions P1 ′, P2 ′,..., P9 ′) at the respective measurement positions P1 to P9 detected in the preliminary measurement. The scan range SR1 at the time of actual measurement is narrower than the scan range SR0 at the time of preliminary measurement, and accordingly, the time required for the entire scan can be shortened.

  In step S13, based on the scan range SR1 calculated in step S12, the main measurement, that is, autofocus in each imaging range IR1 is performed. That is, in step S13, as shown in FIG. 5, the first camera 17a is moved in the XYZ-axis directions like measurement positions P1 ′ → P2 ′ →. For each imaging range IR1, the scan range SR1 is scanned in the Z-axis direction to acquire a two-dimensional image at each Z position, and the displacement of each part in the Z-axis direction is detected.

  This main measurement is performed with higher accuracy than the multipoint autofocus in step S11. However, since the approximate Z value of the workpiece 12 is grasped, the scan range SR1 at the time of this measurement can be set extremely narrow compared with the scan range SR0, and is more efficient than the conventional technique. Can be measured.

  In addition, this invention is not limited to embodiment mentioned above. For example, in the above embodiment, the Z value is obtained from the in-focus position of the image, but it goes without saying that the present invention can also be applied to other image measuring apparatuses that can detect the Z-axis displacement of the workpiece without contact. .

  DESCRIPTION OF SYMBOLS 1 ... Image measuring machine, 2 ... Computer (PC), 3 ... Work, 4 ... Memory | storage device, 5 ... Display apparatus, 6 ... Input device, 11 ... Imaging unit, 12 ... Position control apparatus, 111 ... Imaging device, 112 ... Preliminary imaging device, 121... Plane position control device, 122.

Claims (4)

A stage on which a measurement object is placed;
An imaging device provided so as to be relatively movable with respect to the stage, and imaging the measurement object in a predetermined imaging range narrower than the measurement range and outputting image information;
A position control device that moves the imaging device to a plurality of measurement positions within the measurement range and scans the measurement devices in a direction perpendicular to the stage at each measurement position;
An arithmetic processing unit that calculates a displacement in the scanning direction at each measurement position based on image information of the predetermined imaging range at each measurement position obtained by scanning of the imaging device;
The imaging device is configured to be able to image a preliminary measurement range wider than the predetermined imaging range prior to the main measurement for measuring the displacement in the scanning direction at each measurement position,
The arithmetic processing unit preliminarily measures a displacement in a general scanning direction at each measurement position from image information obtained by scanning the imaging device in the preliminary measurement range during the preliminary measurement. An image measuring device, wherein a scanning range of the imaging device at each measurement position at the time of actual measurement is set based on a result.   The image measurement apparatus according to claim 1, wherein the preliminary measurement range is equal to the measurement range.   The image measuring apparatus according to claim 1, wherein a scanning range at each measurement position during the main measurement is narrower than a scanning range in the scanning direction during the preliminary measurement. The imaging apparatus switches the first imaging system and the second imaging system having different imaging fields of view between the preliminary measurement and the main measurement, and images the imaging range and the preliminary measurement range. The image measurement device according to claim 1.

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