JP2001041710A - Lens magnification recognition method and optical measuring system of optical measuring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens magnification recognition method and an optical measuring system of an optical measuring device which can prevent deterioration of the measuring accuracy caused by a mistake of setting lens magnification by an operator, and moreover does not need setting lens magnification by the operator. SOLUTION: A reference lens of a reference design magnification Stand M is mounted on a turlet, a diameter of the circular pattern of a plate for magnification recognition by the reference lens is measured as the number of reference pixel Stand P in advance, and when an image measuring machine starts measuring, the diameter of the circular pattern of the plate for magnification recognition is measured by using one of tube lenses (28A-28C) as the actual number of pixel Actual P (Step S41). Next, the rough magnification Actual M of one of the tube lenses (28A-28C) is calculated by the expression Actual M=St and M × (Actual P/Stand P) (Step S42), and the closest design magnification to Actual M value calculated is retrieved from the table (table 1) of the tube lens characteristic storage area so that the magnification of one of the tube lenses (28A-28C) can be determined (Step S43).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recognizing a lens magnification of an optical measuring apparatus and an optical measuring system, and more particularly to acquiring necessary measurement information while imaging an object to be measured by an imaging device such as a CCD camera. The present invention relates to a method for recognizing a lens magnification of an optical measuring device such as an image measuring device, a three-dimensional measuring device, and a microscope, and an optical measuring system.

[0002]

2. Description of the Related Art Conventionally, optical measuring devices such as an image measuring device, a three-dimensional measuring device, and a microscope for measuring the size and shape of a work (object to be measured) placed on a table have a magnification of A turret-type variable magnification mechanism in which a plurality of different objective lenses are mounted on a rotatable turret allows a measurement point of a workpiece to be magnified and observed. In this case, the setting of the magnification of the lens is manually performed by the operator.
No. 304022).

[0003]

However, in the above-mentioned optical measuring device, since the magnification of the lens greatly affects the measurement accuracy, if the operator makes a mistake in setting the magnification of the lens, the optical measuring device is used. The measurement results will be inaccurate.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical measuring device capable of preventing a decrease in measurement accuracy due to an erroneous setting of a lens magnification by an operator and eliminating the need for an operator to set a lens magnification. And an optical measuring system.

[0005]

According to a first aspect of the present invention, there is provided a method for recognizing a lens magnification of an optical measuring apparatus, comprising the steps of: measuring a size and shape of an object placed on a table by using a lens and a lens; In a method for recognizing a lens magnification of an optical measuring device for measuring by an imaging means, a pattern for recognizing a lens magnification is attached on a surface of the table, and a dimension of the pattern is measured in advance as a reference pixel number using a lens of a predetermined magnification. At the start of measurement by the optical measuring device,
The dimensions of the pattern are measured as the actual number of pixels using a lens used for measurement, and the magnification of the lens used for the measurement is calculated based on the predetermined magnification, the reference number of pixels, and the actual number of pixels. And

According to the lens magnification recognizing method of the optical measuring device, the dimensions of the lens magnification recognizing pattern affixed on the table surface are measured in advance using a lens of a predetermined magnification as a reference pixel number. Then, at the start of the measurement of the optical measuring device, the dimensions of the pattern are measured as the actual number of pixels using a lens used for the measurement, a predetermined magnification,
Since the magnification of the lens used for measurement is calculated based on the reference number of pixels and the actual number of pixels, the magnification of the lens used for the measurement can be reliably and easily recognized, and as a result, It is possible to prevent a decrease in measurement accuracy due to an incorrect setting of the lens magnification and improve the reliability of the measurement, and to improve the usability of the optical measuring device by eliminating the need for the operator to set the lens magnification. .

The method for recognizing a lens magnification of an optical measuring device according to a second aspect of the present invention is the same as the method for recognizing a lens magnification of the optical measuring device according to the first aspect, except that the following formula: ActualM = StandM × (ActualP / StandP) (where StandM Is the predetermined magnification, ActualP is the actual number of pixels, StandP is the reference number of pixels), and the magnification of the lens used for the measurement (Ac
tualM) is calculated.

According to the method for recognizing the lens magnification of the optical measuring apparatus according to the second aspect, the calculation of the magnification of the lens used for the measurement is performed using the formula ActualM = StandM × (ActualP / StandP). Can be easily and quickly calculated.

According to a third aspect of the present invention, there is provided a method of recognizing a lens magnification of an optical measuring apparatus according to the first or second aspect, wherein the lens magnification recognizing pattern comprises a circular pattern and a square pattern. It is characterized by comprising one of them.

To achieve the above object, an optical measuring system according to a fourth aspect of the present invention is an optical measuring system for measuring the size and shape of an object to be measured placed on a table with a lens and an image pickup means. A lens magnification recognition pattern stuck on the surface of the table, first measuring means for measuring the size of the pattern as a reference pixel number using a lens of a predetermined magnification, and a lens used for measurement at the start of measurement A second measuring means for measuring the size of the pattern as an actual number of pixels using:
The image processing apparatus further includes a calculating unit that calculates a magnification of a lens used for the measurement based on the reference pixel number and the actual pixel number.

According to the optical measuring system of the fourth aspect, the same effect as the method of recognizing the lens magnification of the optical measuring device of the first aspect can be obtained.

According to a fifth aspect of the present invention, in the optical measuring system according to the fourth aspect, the calculating means is configured as follows: ActualM = StandM × (ActualP / StandP) (where StandM is the predetermined magnification) , ActualP is the actual number of pixels, and StandP is the reference number of pixels) using the magnification (Ac) of the lens used for the measurement.
tualM) is calculated.

According to the optical measuring system of the fifth aspect, the same effect as the method of recognizing the lens magnification of the optical measuring device of the second aspect can be obtained.

According to a sixth aspect of the present invention, in the optical measuring system according to the fourth or fifth aspect, the lens magnification recognition pattern comprises one of a circular pattern and a square pattern. I do.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a front view of an optical system unit of an optical measuring device in an optical measuring system according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

The optical measuring device in the optical measuring system according to the present embodiment comprises an image measuring machine. This image measuring machine has a glass table 20 on which a work (object to be measured) is placed and movable in the X-axis direction and the Y-axis direction (FIG. 2) in a horizontal plane, and a column (FIG. The optical system unit 21 is provided so as to be able to ascend and descend in the vertical Z-axis direction (FIG. 1) via a not-shown). The table 20 is moved in the X and Y axis directions by the X and Y axis driving systems 78X and 78Y (FIG. 5), and the optical system unit 21
The table 20 is moved in the Z-axis direction with respect to the table 20 by the Z-axis drive system 78Z (FIG. 5). These X, Y, Z axis drive systems 7
8X to 78Z are provided with X, Y, and Z axis encoders 79X to 79Z (FIG. 5) for measuring the X and Y axis positions of the table 20 and the Z axis position of the CCD camera 24 described later, respectively. At a predetermined position in a corner portion of the table 20, a magnification recognition plate 30, which will be described later, is attached in advance.

The optical system unit 21 has a housing 22. An objective lens 23 is mounted on the lower surface of the housing 22, and a CCD camera 24 and a lighting device 25 are mounted on the upper surface. The CCD camera 24 has an optical axis L of the objective lens 23.
The imaging device is arranged above and configured to capture an image of a workpiece by light from the objective lens 23.

A mirror 2 for reflecting light emitted from the lighting device 25 at right angles to the optical axis L is provided in the housing 22.
6, a beam splitter 27 that reflects light reflected from the mirror 26 on the optical axis L and the objective lens 23, a plurality of tube lenses 28A to 28C having different magnifications (for example, 1 ×, 2 ×, and 5 ×). A switching device 29 that can selectively switch any one of the plurality of tube lenses 28A to 28C on the optical axis L is provided. An illumination device 34 that irradiates light toward the objective lens 23 via the table 20 is disposed below the table 20 and on the optical axis L of the objective lens 23. The illumination device 25 and the illumination device 34 can be selectively used depending on the state of a measurement surface such as a work.

The switching device 29 is provided at a position different from the optical axis L so as to be rotatable about an axis 31 parallel to the optical axis L, and has a radius corresponding to the distance from the axis 31 to the optical axis L. A turret 32 having a plurality of tube lenses 28A to 28C attached at equal angular intervals (120 °), and a positioning device 33 for positioning the turret 32 at respective angular positions where the tube lenses 28A to 28C coincide with the optical axis L.
And a turret drive motor 44 connected to the shaft 31 of the turret 32 via a clutch 43. The rotation angle of the turret 32 is detected by a turret sensor 45.

The positioning device 33 includes three recesses 51 formed by notching at 120 ° intervals on the outer peripheral surface of the turret 32.
A to 51C, and a bearing 52 that is urged in a direction that is always in contact with the outer peripheral surface of the turret 32 and can be engaged with the recesses 51A to 51C. The bearing 52 is supported by an L-shaped bracket 53 attached to the upper surface of the housing 22 via a leaf spring (not shown), and is urged toward the outer peripheral surface of the turret 32 by the leaf spring. The turret 32 is positioned by fitting the bearing 52 into the recesses 51A to 51C by this bias.

The magnification recognition plate 30 affixed to a predetermined position of the corner on the surface of the table 20 has a thickness of 2 to 2.
A mask chart is used in which a predetermined pattern having a known size is deposited on a 3 mm glass substrate by chromium or aluminum. As the pattern shape, a square pattern (FIG. 3) with a known length of each side and a circular pattern (FIG. 4) with a known diameter are used, but a circular pattern is preferable because it has no directionality. In the present embodiment, a circular pattern is used. The size of the pattern is such that the image of the circular pattern can be accommodated within one screen of the CCD camera 24 when the tube lens used is of the highest magnification.
Since this pattern is made of chromium or aluminum vapor, the pattern is preferably measured by transmitted light, and an illumination device 34 is used.

FIG. 5 is a block diagram of a control device of the optical measuring device in the optical measuring system according to the embodiment of the present invention. The control device includes a CPU 71,
The CRT 73 via the display control unit 72, the illumination device 25 via the illumination control unit 74, and the frame grabber 7
5 and the CCD camera 24 via the gain control unit 76,
The turret drive motor 44 and the turret sensor 45 are connected via the turret drive control unit 77, respectively. Further, the CPU 71 includes an X / Y-axis drive system 78X, 7
8Y, X and Y axis encoders 79X and 79Y, a Z axis drive system 78Z and a Z axis encoder 79Z, and a command input unit 8
1 and the memory 82 are connected to each other.

The memory 82 has a work area 83 for storing image data picked up by the CCD camera 24 and processing results of the CPU 71, a design magnification for each of the tube lenses 28A to 28C described later, and dimensions XA and YA (equivalent to one pixel). μ
m) and lens offset values XB, YB, ZB (m
m) in the form of a table shown in Table 1, a tube lens characteristic storage area 84, and each of the axis encoders 79X to 79X.
A counter 85 and the like for storing the X, Y, and Z axis positions detected at 9Z are provided.

In the above configuration, when the illuminating device 25 is used, the light from the illuminating device 25 is reflected by the mirror 26, then by the beam splitter 27, and placed on the table 20 through the objective lens 23. Irradiated on the work. When the lighting device 34 is used, the light from the lighting device 34 is directly applied to the work through the table 20. The light from the objective lens 23 passes through the beam splitter 27 and is
The image is magnified to a magnification of A to 28C and imaged by the CCD camera 24. The image of the CCD camera 24 is converted into image data by pixels arranged vertically and horizontally. The image data of each pixel is stored as a digitized gray value between 0 and 255 in an image data storage area 83 in the memory 82.

Hereinafter, the table of Table 1 will be described.
Each data in the table (Table 1) is unique to the image measuring device, and is created in advance for each image measuring device.

[0027]

[Table 1]

In Table 1, ID number 001 corresponds to tube lens 28A, and ID number 002 corresponds to tube lens 28A.
B and the ID number 003 correspond to the tube lens 28C, respectively.

The table (Table 1) shows the design magnification of each lens of ID numbers 001 to 003 corresponding to the tube lenses 28A to 28C, dimensions XA, YA corresponding to one pixel,
Including lens offset values XB, YB, ZB,
It includes a reference magnification StandM for the reference lens, a dimension equivalent to one pixel, an offset value of the lens, and a reference pixel number StandP described below.

The dimensions XA and YA corresponding to one pixel are values measured in advance in the X and Y axis directions corresponding to one pixel in the image of the CCD camera 24 obtained by the reference lens and the tube lenses 28A to 28C. The offset values XB, YB, ZB of the lenses are values measured in advance in the axial direction of the image when the reference lens and each of the tube lenses 28A to 28C are positioned on the optical axis L.

Hereinafter, the measurement processing of the reference pixel number StandP will be described with reference to FIG. FIG. 6 is a flowchart illustrating a procedure of the measurement process of the reference pixel number StandP.

In FIG. 6, first, a reference design magnification Stand
An M (1 × in this embodiment) reference lens is mounted on the turret 32, and the diameter of the circular pattern of the magnification recognition plate 30 is determined using this reference lens as the reference pixel number StandP.
(Step S31). At this time, if the measured number of pixels has a fraction, the number of pixels is displayed as a decimal by an interpolation method (the same applies to the following measurement). In the present embodiment, as shown in FIG. 7, the X and Y coordinates of three points having different edges of the circular pattern 50 are measured, and the diameter of the circular pattern 50 is determined from the measured three X and Y coordinates by a known method. It is calculated as the number of pixels.

Next, the obtained reference pixel number StandP
Is stored in the tube lens characteristic storage area 84 as data of a table (Table 1) (step S32).

At the start of the measurement by the image measuring device, the following lens magnification setting operation is performed using the reference magnification StandM and the reference pixel number StandP stored in the table (Table 1) in advance.

FIG. 8 is a flowchart showing a procedure of a lens magnification setting operation.

In FIG. 8, first, when a turret rotation command is input from the command input section 81 (step S11),
The CPU 71 holds the image displayed on the CRT 73 (step S12). That is, the CCD camera 24
The image data picked up by the image data storage area 8
3 and the image data is continuously displayed on the CRT 73 (FIG. 9A). Next, the turret drive motor 44 is driven via the turret drive control unit 77,
Based on a signal from the turret sensor 45, the motor 44 is stopped when any of the desired tube lenses 28A to 28C is rotated by an angle positioned on the optical axis L (step S13). The screen of the CRT 73 at this time is shown in FIG.
(B) shown. Thereby, the used tube lens 28
As A to 28C reach the vicinity of the optical axis L, the bearing 52 starts to fit into the corresponding recesses 51A to 51C.
Here, when the clutch 43 is disengaged, the motor 44 is disconnected from the turret 32 and the rotational resistance of the motor 44 is eliminated, so that the turret 32 starts to engage with the concave portions 51A to 51A.
It is automatically rotated and positioned up to the angular position where 51C is completely fitted to bearing 52.

Next, lens magnification processing recognition processing for determining the magnification of the selected tube lenses 28A to 28C by the processing of FIG. 10 described later is performed (step S14). Next, an automatic light adjustment process is performed so that the light amount of the illumination device 25 and the camera gain of the CCD camera 24 are automatically set to optimal values every time the magnification of the lens changes (step S15), as will be described later. After performing the turret optical axis offset processing by the processing of FIG. 11 (step S16), the hold state of the image is released (step S17). As a result, the image held on the CRT 73 (FIG. 9)
(A)) Instead of the selected tube lens 28A
An enlarged image with a magnification of ~ 28C is displayed (FIG. 9).
(C)).

Hereinafter, the lens magnification recognition process in step S14 of FIG. 8 will be described with reference to FIG. FIG. 10 is a flowchart showing the procedure of the lens magnification recognition process in step S14 of FIG.

In FIG. 10, first, one of the tube lenses 28A to 28C used for measurement is used to determine the diameter of the circular pattern of the magnification recognition plate 30 by the actual number of pixels.
Measured as ActualP and the measured value
(Step S41). This measurement measures the X and Y coordinates of three different points of the three edges of the circular pattern 50 in the same manner as the above-described measurement processing of the reference pixel StandP, and uses a known method from the measured three X and Y coordinates. Is used to measure the diameter of the circular pattern 50 as the number of pixels. Next, the tube lens 28 is obtained from the StandM value and StandP value of the table (Table 1) and the ActualP value of the work area 83.
One approximate magnification ActualM of A to 28C is calculated by the following equation (1).
(Step S42).

ActualM = StandM × (ActualP / StandP) (1) Next, the design magnification closest to the calculated ActualM is retrieved from the table (Table 1) of the tube lens characteristic storage area 84 to find the magnification of the lens to be used. Determine (Step S
43).

After the magnification of the tube lens is determined in this manner, the offset values XB, YB, ZB of the tube lens are read from the table (Table 1) and set in the counter 85 in step S16 of FIG. CCD
After correcting the displacement of the image of the camera 24, the measurement by the image measuring device is performed. Obtaining the dimensions and coordinate values of the image by multiplying the distance (number of pixels) on the image of the CCD camera 24 by the dimensions (XA, YA) corresponding to one pixel of the tube lens read from the table (Table 1). Can be.

Hereinafter, the turret optical axis offset processing in step S16 of FIG. 8 will be described with reference to the flowchart of FIG.

First, the offset values XB, YB, ZB corresponding to the tube lens selected from the tube lens characteristic storage area 84 of the memory 82 are fetched (step S).
21), the value of the counter 85 of each axis is corrected using the value (step S22). For example, if the counter value before zooming is X = 0.000, Y = 0.000, Z = 0.0
00, in the state after zooming, X = 0.001, Y = 0.
002, Z = 0.0015,
These values X = 0.001, Y = 0.002, Z = 0.
0015 is set in the counter 85. Next, the offset value table 20 is moved in the X and Y axis directions, and the optical unit 21 is moved in the Z axis direction (step S).
23). As a result, the displacement of the image of the CCD camera 24 can be corrected.

According to the present embodiment, the magnification of the tube lenses 28A to 28C used for measurement can be reliably and easily recognized, and as a result, the measurement accuracy due to an erroneous setting of the lens magnification by the operator is reduced. It is possible to prevent the drop and improve the reliability of the measurement, and to improve the usability of the optical measuring device by eliminating the need for the operator to set the lens magnification.

In the present embodiment, the lens magnification recognition processing of FIG. 10 is executed by a program, but may be executed by an operator's button operation or the like.

In the present embodiment, the present invention is applied to an image measuring machine having a turret type zoom mechanism.
The present invention can also be applied to an image measuring device equipped with a zoom lens type variable power mechanism, and an image measuring device of an interchangeable lens type.

In the above embodiment, the present invention is applied to an image measuring device as an optical measuring device, but the present invention can also be applied to a three-dimensional measuring device and a microscope.

Further, the present invention can be applied as an automatic probe ID generation function when mounted as an image probe on a coordinate measuring machine. That is, when there are a plurality of image probes having different lens magnifications, the CMM needs to know which probe is actually mounted, but an ID is set for each lens as shown in Table 1. Thus, after recognition of the lens magnification, the ID corresponding to the lens can be output to the coordinate measuring machine.

[0049]

As described in detail above, according to the method for recognizing a lens magnification of an optical measuring device according to the first aspect, a lens magnification recognition apparatus attached to a table surface using a lens of a predetermined magnification. The dimensions of the pattern are measured in advance as the reference number of pixels, and at the start of the measurement of the optical measuring device, the dimensions of the pattern are measured as the actual number of pixels using a lens used for measurement. Since the magnification of the lens used for the measurement is calculated based on the number of pixels, the magnification of the lens used for the measurement can be reliably and easily recognized, and as a result, the setting of the lens magnification by the operator can be performed. The accuracy of measurement can be improved by preventing a decrease in measurement accuracy due to errors, and the usability of the optical measuring device is eliminated by eliminating the need for the operator to set the lens magnification. It is possible to above.

According to the method for recognizing the lens magnification of the optical measuring device according to the second aspect, the calculation of the magnification of the lens used for the measurement is performed by using the formula ActualM = StandM × (ActualP / StandP), so that the lens is used. Can be easily and quickly calculated.

According to the optical measuring system of the fourth aspect, the same effect as the method of recognizing the lens magnification of the optical measuring device of the first aspect can be obtained.

According to the optical measuring system of the fifth aspect, the same effect as the method of recognizing the lens magnification of the optical measuring device of the second aspect can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an optical system unit of an optical measuring device in an optical measuring system according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is an explanatory view of a lens magnification recognition plate having a square pattern.

FIG. 4 is an explanatory diagram of a lens magnification recognition plate having a circular pattern.

FIG. 5 is a block diagram showing a configuration of a control device of the optical measuring device in the optical measuring system according to the embodiment of the present invention.

FIG. 6 is a flowchart illustrating a procedure of a measurement process of a reference pixel number StandP.

FIG. 7 is an explanatory diagram of a method for calculating the diameter of a circular pattern.

FIG. 8 is a flowchart of a lens magnification setting operation.

FIG. 9 is a diagram showing a hold screen and a hold release screen.

FIG. 10 is a flowchart illustrating a procedure of a lens magnification recognition process in step S14 of FIG. 8;

FIG. 11 is a flowchart illustrating a procedure of a turret optical axis offset process in step S16 of FIG. 8;

[Explanation of symbols]

 Reference Signs List 20 table 24 CCD camera 25 lighting device 28A-28C tube lens 29 switching means 71 CPU 83 work area 84 tube lens characteristic area 85 counter

Continued on the front page F term (reference) 2F064 MM02 MM04 MM14 MM24 MM26 MM32 2F065 AA00 AA03 AA04 AA07 AA26 AA53 AA56 DD00 EE00 EE05 FF02 FF04 FF42 FF61 FF66 FF67 HH13 HH15 NN12 NN13 NN03 JJ03 LL09 QQ03 QQ21 QQ23 QQ24 QQ26 QQ28 QQ51 2H052 AD33

Claims (6)

[Claims] In a method for recognizing a lens magnification of an optical measuring device for measuring a size and a shape of an object to be measured placed on a table by a lens and an image pickup means, a lens magnification recognizing pattern is formed on a surface of the table. The dimensions of the pattern are pre-measured as a reference pixel number using a lens of a predetermined magnification by pasting, and at the start of measurement by the optical measuring device, the dimensions of the pattern are measured using a lens to be used for measurement by the actual number of pixels. Measured as the predetermined magnification,
A lens magnification recognition method for an optical measuring device, comprising calculating a magnification of a lens used for the measurement based on a reference pixel number and an actual pixel number. 2. The following formula ActualM = StandM × (ActualP / StandP) (where StandM indicates the predetermined magnification, ActualP indicates the actual number of pixels, and StandP indicates the reference number of pixels). Magnification of the lens used (Ac
2. The lens recognition method for an optical measuring device according to claim 1, wherein tualM) is calculated. 3. The method according to claim 1, wherein the lens magnification recognition pattern comprises one of a circular pattern and a square pattern. 4. An optical measuring system for measuring the size and shape of an object to be measured placed on a table by a lens and an image pickup means, wherein a lens magnification recognition pattern attached to a surface of the table, A first measuring means for measuring the size of the pattern as a reference number of pixels using a magnification lens, and a second measuring means for measuring the size of the pattern as an actual number of pixels using a lens used for measurement at the start of measurement. An optical measurement system, comprising: a measuring unit for calculating the magnification of the lens used for the measurement based on the predetermined magnification, the reference pixel number, and the actual pixel number. 5. The calculating means uses the following formula: ActualM = StandM × (ActualP / StandP) (where StandM indicates the predetermined magnification, ActualP indicates the actual number of pixels, and StandP indicates the reference number of pixels). And the magnification of the lens used for the measurement (Ac
The optical measuring system according to claim 4, wherein tualM) is calculated. 6. The optical measurement system according to claim 4, wherein the lens magnification recognition pattern comprises one of a circular pattern and a square pattern.