JP2001165630A - Sensor calibration device for surface property measuring machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor calibration device capable of easily and precisely performing the coordinate calibration of an image sensor used for a surface property measuring machine. SOLUTION: This device comprises the outside reference side face 20 of a cylinder 20 having a central axis C; the upper end surface of the cylinder 20 orthogonal to the central axis C; an inclined surface part 14 provided in the connecting part between the reference side face 20 and an upper end face 13; an illuminating light reflection part 30 provided in the vicinity of the lower part of the cylinder 20; and a fixing part 40 to be fixed to the base of the measuring machine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensor calibration device for measuring the shape of an object to be measured, and more particularly to a coordinate calibration device for an image sensor.

[0002]

2. Description of the Related Art As a sensor for measuring the surface properties of an object to be measured, a contact type stylus sensor and a non-contact sensor are used. There is a great demand for a sensor that can collect a large amount of information at a high speed without damaging the device. This image sensor tends to be frequently used for measuring two-dimensional or three-dimensional shapes, particularly among surface properties, but a touch signal probe has conventionally been the mainstream sensor in this field.

Various probes are used as the touch signal probe according to the purpose of measurement and the shape of the object to be measured. Even when measuring one object to be measured, these probes are exchanged for measurement. In some cases, in the measurement of an object to be measured having a complicated shape, various kinds of touch signal probes are automatically exchanged by an automatic probe exchanging device, and various kinds of measurements are continuously performed. In this case, the mounting attitude changes slightly with the replacement of the touch signal probe, so when performing precision measurement, measure the precision reference sphere with the surface as the calibration reference plane and calibrate the touch signal probe coordinates. I do. (See, for example, JP-A-7-146130.)

[0004] On the other hand, the conventional image sensor is much heavier and larger than a touch signal probe weighing several hundred grams because it includes an imaging unit and a lighting unit. For this reason, the conventional image sensor cannot be easily replaced, and has been used while being attached to the measuring machine. Therefore, the coordinate calibration had to be performed only once.

[0005]

On the other hand, a small and lightweight image sensor has been developed at a practical level, and the image sensor and the touch signal probe are mixed according to the type of measurement as in the conventional touch signal probe. In the case of replacement, coordinate calibration after attaching the image sensor is required. However, in the measurement of the reference sphere used for calibration of the conventional touch signal probe, the image sensor
Calibration with high accuracy and high accuracy was not easy.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it is an object of the present invention to provide a sensor calibrating apparatus capable of easily performing high-accuracy coordinate calibration even when an image sensor is replaced in an exchangeable image sensor. With the goal.

[0007]

In order to achieve the above object, the present invention provides an outer surface of a cylinder having a central axis,
A reference side surface that forms a calibration reference surface, an upper end surface of the cylinder that is orthogonal to the central axis, and that forms a height reference surface, and an inclined surface provided at a joint between the reference side surface and the upper end surface, An illumination light reflecting portion provided near the lower portion of the cylinder;
And a fixing part for fixing to a base of the measuring machine. According to the present invention, when the sensor calibration device is imaged from above with an image sensor including an illumination device, the illumination light reflecting unit reflects the illumination light and is imaged in a bright color,
The slope portion is imaged in dark color because the illumination light is reflected to the side. Therefore, the arc-shaped or straight-line contour of the reference side surface is clearly imaged, and the center coordinates of the circle of the reference side surface, that is, the center axis coordinates can be obtained from this image, so that the coordinate calibration of the image sensor can be performed easily and precisely.

Normally, when a bright portion and a dark portion are imaged by an image sensor, the bright portion tends to expand (a phenomenon in which a dark portion adjacent to the bright portion is imaged in a bright color). Since the cross section is circular, this expansion occurs around the entire contour of the circle. Therefore, there is an effect that no error occurs in the obtained center coordinates.

Further, the present invention is characterized in that the reference side surface includes a plane parallel to the central axis. According to this configuration, the reference side surface is imaged in an alphabet D shape. Therefore, by measuring the inclination of the D-shaped linear portion, the rotation inclination of the image sensor, that is, the rotation angle of the image sensor around the axis of the objective lens can be calibrated.

Further, the illumination light reflecting portion of the present invention includes a light transmitting sphere for reflecting the illuminated light at the same angle and in the opposite direction, and a substrate for fixing the light transmitting sphere. . As a result, the translucent sphere reflects the illumination light by the so-called cat's eye effect, so that even for illumination light from any direction, the light is reflected in the opposite direction, so that the contour of the reference side surface is more sharply defined. Images can be taken.

The fixing portion of the present invention includes a fixing member for fixing to a base of the measuring instrument, and a rotation for adjusting the reference side surface to rotate at an arbitrary angle about the center axis with respect to the fixing member. An adjusting member, and an inclination adjusting member that adjusts the inclination of the central axis to an arbitrary angle with respect to the fixed member. With this configuration, when the sensor calibration device is installed on the base (or the mounting table) of the measuring device, the mounting and the posture adjustment can be easily performed.

Further, the present invention is characterized in that the upper end face includes a calibration operation reference mark. As a result, in the calibration work, the calibration work can be automated by executing the calibration part program by adjusting the reference of the image sensor (for example, the optical axis of the objective lens) to the calibration operation reference mark position.

Further, the present invention provides an inner surface of a round hole provided on a reference member in a vertical direction and having one opening on an upper side, the reference inner surface forming a calibration reference surface; An upper end surface of the reference member, which is orthogonal to the central axis, a slope portion provided at a joining portion between the reference inner side surface and the upper end surface,
An illumination light reflecting part provided near the lower part of the round hole and a fixing part for fixing to a base of the measuring instrument are provided. Further, a reference plane parallel to the central axis is provided on an outer side surface of the reference member, and a slope portion is provided at a joining portion between the reference plane and the upper end surface. According to the present invention, since the circular inner contour of the reference inner surface can be imaged clearly and over the entire circumference, the center coordinates of the circle of the reference inner surface, that is, the center axis coordinates of the round hole, are more accurately obtained from this image. And the coordinate calibration of the image sensor can be performed more precisely.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. In all the drawings, components denoted by the same reference numerals represent the same components. FIG. 1 is a schematic perspective view of a sensor calibration device of a surface texture measuring device according to a first embodiment of the present invention.

In FIG. 1, a sensor calibrating device 1 of the present embodiment is an outer surface of a cylinder 10 having a central axis C, a horizontal cross section of which is an arc reference side surface 11, and a straight line parallel to the central axis. And a reference side surface 12, and both of them constitute a reference side surface 20. Further, the column 10 has an upper end surface 13 orthogonal to the central axis C, and a slope portion 14 is provided at a joint portion between the upper end surface 13 and the reference side surface 20. A calibration operation reference mark 15 is provided on a part of the upper end surface 13.

In this embodiment, the calibration operation reference mark 15 is a round hole having a small inner diameter. An illumination light reflector 30 is provided in the vicinity of the lower part of the cylinder 10, and the cylinder 10 and the illumination light reflector 30 are fixed to a fixing unit 30 for fixing the sensor calibrator 1 to the base of the measuring machine. It is fixed to. The outer diameter of the portion of the cylinder 20 where the illumination light reflecting portion 30 is installed is small,
It is configured in a constricted shape, and the illumination light reflecting portion 30 is installed so as to enter the constricted portion. The shapes of the reference side surface 20 and the upper end surface are finished with sufficient accuracy necessary for calibration.

FIG. 2A is a plan view of the sensor calibrating device 1, and FIG. 2B is a side view showing a partial vertical cross section of the sensor calibrating device 1. The fixing part 40 includes a mounting screw 41 for fixing the sensor calibration device 1 to the table of the measuring machine.
And a fixing base 42 having a hole for inserting and fixing a mounting screw 41 at the center thereof, and these both constitute a fixing member. The lower side surface of the fixing base 42 is tapered (partially conical) over the entire circumference.
4 comes into contact.

The fixed base 42 is fitted into a concave portion below the disk-shaped rotating base 43, and the fixed base 42 and the rotating base 43 rotate relative to each other. The rotation fixing screw 44 screwed into the hole is tightened, and the rotation fixing screw 44
Are fixed to each other when the tip of the abutment comes into contact with the lower tapered portion on the side of the fixed base 42. Since the screw holes on the side of the rotating base 43 are provided at one position or at a plurality of positions at an equal angle in a horizontal plane, the tightening with the rolling fixing screw 44 can be performed at one or a plurality of positions. Rotation base 43 and rotation fixing screw 44
Constitutes a rotation adjusting member.

A concave portion is provided at the center of the upper portion of the rotating base 43,
The tilt base 45 is placed via the tilt ball 46. The inclined base 45 and the rotating base 43 are fixed by an inclined fixing screw 47 provided at an equal angle in a horizontal plane. In the present embodiment, three inclined fixing screws 47 every 120 degrees are used. Here, a spring 48 is interposed in the inclination fixing screw 47 so that an appropriate adjustment force is applied when the inclination is adjusted by the inclination fixing screw 47. Here, the inclined sphere 46, the inclined base 45, the inclined fixing screw 47, and the spring 48 constitute an inclination adjusting member.

On the upper part of the inclined base 45, the illumination light reflecting part 3 is provided.
0 is the reflector fixing screw 3 via the reflector fixing ring 33.
It is fixed at 4. At the center of the inclined base 45 is a column 1
0 is fixed. FIG. 3 shows a vertical sectional view of the illumination light reflecting section 30. The illumination light reflecting section 30 includes a light transmitting sphere 31 and a substrate 32. The translucent sphere 31 is fixed to the substrate 32 by bonding or the like, and reflects the illumination light emitted from an arbitrary direction at the same angle and in the opposite direction by the so-called cat's eye effect. The diameter of each of the light-transmitting spheres 31 is approximately 20 to 50 μm, and in this embodiment, light-transmitting spheres of the same size are used.

Next, a procedure for installing the sensor calibration device 1 on a table of a measuring machine will be described. First, the fixing base 42 is fixed to the table of the measuring machine by the mounting screw 41. Next, the rotating base 43 is put on the fixed base 42,
The rotation fixing screw 44 is lightly tightened and fixed. At this time, the rotating base 43, the inclined sphere 46, the inclined base 45, the illumination light reflecting unit 3
The cylinder 0, the cylinder 10 and the like are assembled in advance, but the attachment of the inclined base 45 to the rotating base 43 is lightly fixed by an inclined fixing screw 47 with a spring 48 interposed therebetween.

Thereafter, a touch signal probe is attached to the measuring machine, and the upper end surface 13 is measured. From this measurement result, the three inclined fixing screws 47 are adjusted so that the upper end surface 13 is horizontal (parallel to the XY plane). Thereafter, the straight reference side surface 12 is measured with a touch signal probe, and the inclination of the straight reference side surface 12 in the XY plane is 0 degree (or 180 degrees).
After adjusting the screw by loosening the rotation fixing screw 44 so as to obtain the degree, the fixing is performed.

Next, a method of calibrating the coordinates of an image sensor using the sensor calibration device 1 will be described. First, the upper end surface 13 is imaged by the image sensor S, and its Z-axis coordinates are obtained. This is done using the autofocus function of the image sensor.

Next, the XY coordinates of the central axis C are determined by determining the contour of the reference side surface. FIG. 4A is a schematic diagram illustrating a calibration state of the image sensor S. As shown in this figure, the image sensor S images the contour of the arc reference side surface 11 of the sensor calibration device 1 over three or more locations. In this figure, an example of measurement by epi-illumination is shown. In this way, the epi-illumination light L is reflected by the illumination light reflecting portion 30 and the upper end surface 13 and becomes return light to the image sensor S. Slope 1
In No. 4, since the light is reflected in a substantially horizontal direction, the light does not return to the image sensor S. Therefore, the captured image is shown in FIG.
(B), the slope portion 14 becomes dark, and the other portions become light. From this measurement result, the coordinates (XY coordinates) of point P in FIG. 4B, which is the boundary point between dark and light colors, are obtained. The coordinates of three or more boundary points are determined from the results of imaging the contour at three or more locations, and the center coordinates of the contour of the arc reference side surface 11 are determined.

Next, the contour of the straight reference side surface 12 is similarly imaged at two or more locations. From this result, the inclination of the image sensor is determined by calculating the inclination of the linear portion.
That is, the rotation angle about the axis of the objective lens of the image sensor can be measured. From the difference between these coordinate values and the rotation angle and the measurement result at the time of the previous calibration, an exchange mounting error of the image sensor can be obtained.

In performing these calibration operations, a part program for calibration may be prepared in a coordinate measuring machine or the like capable of automatic measurement, and automatic calibration may be performed.
That is, the image sensor is positioned such that the reference point of the image sensor (for example, the optical axis of the objective lens) matches the calibration operation reference mark 15 with respect to the XY coordinates. At this time, the Z coordinate may be any position as long as the image sensor can automatically focus on the upper end surface 13. Next, when the calibration part program is executed, the above-mentioned respective calibration procedures are automatically executed sequentially, and the automatic calibration is completed.

FIG. 5 is a view showing a vertical cross section of a reference member of the sensor calibration device 2 of the second embodiment. In this embodiment, the outer shape of the reference member 50 is a cylinder,
The external shape may be arbitrary. A vertical circular hole is provided at the center of the reference member 50, and is opened to the upper side. The reference inner side surface 51 of the round hole is machined with sufficient shape accuracy necessary for calibration. The upper end of the reference member 50 is provided with an upper end surface 53 orthogonal to the center axis C2 of the round hole, and is processed with sufficient plane accuracy required for calibration. This upper end surface 53
In addition, a slope portion 54 is provided at a joint portion of the reference inner side surface 51.

Further, a linear reference plane 55 (reference plane) parallel to the central axis C2 is provided on the outer side surface of the reference member 50, and is processed with sufficient shape accuracy necessary for calibration.
A straight slope portion 56 (slope portion) is provided at a joint between the straight reference surface 55 and the upper end surface 53. The illumination light reflecting portion 60 is provided at the bottom of the round hole. The configuration of the illumination light reflecting portion 60 is the same as that of the illumination light reflecting portion 3 in the first embodiment.
Since it is the same as 0, the description is omitted.

Although an illuminating light reflecting portion (not shown) is provided below the straight reference surface 55, it is the same as the illuminating light reflecting portion 30 in the first embodiment, and a description thereof will be omitted. In order to provide the illumination light reflecting portion, the reference member 5 is required.
0 may be provided with a concave portion (corresponding to a constricted portion in the first embodiment). Further, a small hole for discharging dust is provided at the bottom of the round hole, but is not always necessary.

The reference member 50 corresponds to the first embodiment shown in FIG.
(B) is attached to the inclined base 45, and its configuration is the same, so that detailed description is omitted. The procedure for installing the sensor calibration device 2 on the table of the measuring machine and the method for calibrating the coordinates of the image sensor using the sensor calibration device 2 are the same as those in the first embodiment. When the reference inner side surface of the sensor calibration device 2 of the second embodiment is imaged by an image sensor according to FIG. 4A, the contour of the entire circumference of the circle can be measured. Calibration can be performed.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to these embodiments, and can be modified without departing from the spirit of the present invention. For example, although the sensor calibrated by this sensor calibrator has been described only for an image sensor, it can also be used for calibrating a touch signal probe. It is also easy to determine the difference between the measured coordinate values of the signal probe).

The description has been made only on the case where the reference side surfaces are all parallel and perpendicular to the Z axis and the upper end surface is parallel and horizontal to the XY plane. However, this sensor calibration device is installed with the central axis inclined. You may. With this configuration, when the image sensor itself can be tilted, calibration in the tilted state can be performed. Further, the reference inner side surface in the second embodiment may be provided at the center of the column in the first embodiment. In this way, a sensor calibration device that can exhibit both effects can be configured.

In the above embodiment, the description has been made only for the case where the light-transmitting spheres all have the same size. However, the present invention can be implemented even if the light-transmitting spheres 31 having different sizes are used.
Further, although the calibration operation reference mark is described as being limited to a minute round hole, a cross mark crossing a straight line may be used, and these marks may be formed by printing or painting. Further, a translucent non-reflective plate may be provided above the round hole in the second embodiment to prevent dust from entering the round hole.

[0034]

According to the present invention, even in the case of an exchangeable image sensor, it is possible to accurately and easily calibrate a mounting error for each exchange, and to set the coordinates between the image sensor and the touch signal probe. Offset measurement is also possible.
It is possible to sufficiently bring out the performance of a lightweight image sensor.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of a sensor calibration device of a surface texture measuring device according to a first embodiment of the present invention.

FIG. 2 is a plan view (A) of the sensor calibration device and a side view (B) showing a partial vertical cross section.

FIG. 3 is a vertical sectional view of an illumination light reflecting section of the sensor calibration device.

FIG. 4 is a schematic diagram (A) showing a calibration state of the image sensor.
And the captured image (B).

FIG. 5 is a vertical sectional view of a reference member of a sensor calibration device of a surface texture measuring device according to a second embodiment of the present invention.

[Explanation of symbols]

 1, 2 Sensor calibration device 10 Cylinder 11 Arc reference side surface 12 Straight reference side surface 13 Upper end surface 14 Slope portion 15 Calibration operation reference mark 20 Reference side surface 30 Illumination light reflecting portion 40 Fixed portion 50 Reference member

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[Procedure amendment]

[Submission date] December 14, 1999 (1999.12.
14)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction contents]

In this embodiment, the calibration operation reference mark 15 is a round hole having a small inner diameter. An illumination light reflector 30 is provided in the vicinity of the lower part of the cylinder 10, and these cylinders 10 and the illumination light reflector 30 are fixed to a fixing unit 40 for fixing the sensor calibration device 1 to a base of the measuring machine. It is fixed to. The outer diameter of the portion of the cylinder 20 where the illumination light reflecting portion 30 is installed is small,
It is configured in a constricted shape, and the illumination light reflecting portion 30 is installed so as to enter the constricted portion. The shapes of the reference side surface 20 and the upper end surface are finished with sufficient accuracy necessary for calibration.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 1

[Correction method] Change

[Correction contents]

FIG.

Claims (7)

[Claims] 1. An outer surface of a cylinder having a central axis,
A reference side surface that forms a calibration reference surface, an upper end surface of the cylinder that is orthogonal to the central axis, and that forms a height reference surface, and an inclined surface provided at a joint between the reference side surface and the upper end surface, An illumination light reflecting portion provided near the lower portion of the cylinder;
A sensor calibration device for a surface texture measuring device, comprising: a fixing portion for fixing to a base of the measuring device. 2. The sensor calibration apparatus according to claim 1, wherein the reference side surface includes a reference plane parallel to the central axis. 3. The sensor calibrating device according to claim 1, wherein the illumination light reflection unit includes a light-transmitting sphere that reflects irradiated illumination light at the same angle and in the opposite direction, and a light-transmitting sphere. A sensor calibration device for a surface texture measuring device, comprising a substrate to be fixed. 4. The sensor calibration device according to claim 1, wherein the fixing unit includes a fixing member for fixing to a base of the measuring device, and the reference side surface with respect to the fixing member. A surface property measurement comprising: a rotation adjustment member that adjusts the rotation around the central axis to an arbitrary angle; and an inclination adjustment member that adjusts the inclination of the central axis to an arbitrary angle with respect to the fixed member. Machine calibration equipment. 5. The sensor calibration device for a surface texture measuring device according to claim 1, wherein the upper end surface includes a calibration operation reference mark. 6. An inner surface of a round hole provided in the reference member in a longitudinal direction and having one opening on an upper side, the reference inner surface forming a calibration reference surface, and being perpendicular to a central axis of the round hole. Do
An upper end surface of the reference member, a slope portion provided at a joint portion between the reference inner side surface and the upper end surface, an illumination light reflecting portion provided near the lower portion of the round hole, and fixed to a base of a measuring instrument. A sensor for calibrating a surface texture measuring device, comprising: 7. The sensor calibration device according to claim 6, wherein a reference plane parallel to the central axis is provided on an outer surface of the reference member, and a slope portion is provided at a joint between the reference plane and the upper end surface. A sensor calibration device for a surface texture measuring device, comprising: