JP3149570B2 - Non-contact shape measuring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for measuring the shape of an object to be measured in a non-contact manner by using an optical distance detecting means.

[0002]

2. Description of the Related Art Conventionally, as means for measuring the shape of an object to be measured such as various molded products or resin molds, an optical distance sensor or the like is used instead of directly contacting a measuring needle or the like with the surface to be measured. There is known a technique for measuring the shape of the surface to be measured without making contact with the surface to be measured. For example, Japanese Patent Application Laid-Open No. 2-272
No. 308 discloses that a light is emitted from a light emitting element to a surface of an object to be measured in a predetermined direction, and the reflected light is received by a light receiving element. Is calculated using a triangulation method.

In the above-described light-reflection type distance sensor, the measurable distance range is limited. If a point to be measured exists at a position beyond this range, it may be due to light reflection or the like. Erroneous detection. Therefore, Japanese Patent Publication No. 2-16965 discloses that the distance value detected by the distance sensor is constantly monitored to determine whether or not the distance value is within a predetermined allowable distance range. In the case where the distance deviates, the actual distance is adjusted so that the distance between the distance sensor and the surface to be measured again falls within the allowable distance range before the measurement of the next measurement point is performed. I have.

[0004]

The above device monitors the current distance detection value, and moves the object to be measured in the optical axis direction when the value is likely to be out of the measurable range. By adjusting the distance, the next point to be measured is prevented from actually deviating from the measurable range in advance, but the surface shape of the object W is measured from the surface to the distance sensor. When there is a large step where the distance changes suddenly in the scanning direction, even if the distance detection value before the sudden change in the distance is sufficiently within the measurable range, it is measured immediately at the next measurement point where the distance suddenly changes In some cases, the data may be out of the possible range. In this case, it is not possible to accurately determine whether the current data is valid. For example, as shown in FIG. 9, when the optical distance sensor 30 scans across a large step on the surface of the workpiece W, the detection distance is sufficiently within the measurable range on the near side (left side in the figure) of the step. Despite being settled, at the time when the sensor passes the step, the actual relative distance from the optical distance sensor 30 to the surface of the workpiece W sharply increases and goes out of the measurable range. If the detected value is determined to be valid and imported, the actual surface shape may be erroneously recognized as the shape shown by the broken line 90 in FIG.

[0005] In view of such circumstances, an object of the present invention is to provide an apparatus capable of accurately and non-contactly measuring the surface shape of an object to be measured having a large step or the like.

[0006]

SUMMARY OF THE INVENTION The present invention provides a light emitting member for irradiating light to the surface of an object to be measured, and a light receiving member for receiving light emitted from the light emitting member and reflected from the surface of the object to be measured. And a means for calculating a distance to each position on the surface of the object based on the output of the light receiving member. Means for obtaining a final measurement result based on a first measurement result obtained by performing the measurement under the condition and a second measurement result obtained by performing the measurement under the second distance condition. (Claim 1).

For example, the distance between the object to be measured and at least one of the light emitting member and the light receiving member may be different between the first distance condition and the second distance condition.

The present invention also provides a light emitting member for irradiating light to the surface of the object to be measured, a light receiving member for receiving light emitted from the light emitting member and reflected from the surface of the object to be measured,
Means for obtaining a distance to each position on the surface of the object to be measured based on the output of the light receiving member, wherein the same measurement position on the object is measured under a first distance condition. Means for determining whether the measurement result is appropriate based on the first measurement result obtained by performing the measurement and the second measurement result obtained by performing the measurement under the second distance condition. (Claim 3).

For example, when the distance obtained by the measurement under the first distance condition and the distance obtained by the measurement under the second distance condition are within a predetermined range, it is determined that the measurement result is appropriate. (Claim 4).

The present invention also provides a light emitting member for irradiating light to the surface of the object to be measured, a light receiving member for receiving light emitted from the light emitting member and reflected from the surface of the object to be measured,
Means for obtaining a distance to each position on the surface of the object to be measured based on the output of the light receiving member, wherein the same measurement position on the object to be measured is measured under the first measurement condition. A means for obtaining a final measurement result based on a first measurement result obtained by performing the measurement and a second measurement result obtained by performing the measurement under the second measurement condition. (Claim 5).

The present invention also provides a light emitting member for irradiating light to the surface of the object to be measured, a light receiving member for receiving light emitted from the light emitting member and reflected from the surface of the object to be measured,
Means for obtaining a distance to each position on the surface of the object to be measured based on the output of the light receiving member, wherein the same measurement position on the object to be measured is measured under the first measurement condition. Means for determining whether the measurement result is appropriate based on the first measurement result obtained by performing the measurement and the second measurement result obtained by performing the measurement under the second measurement condition. (Claim 7).

For example, the first measurement condition and the second measurement condition may have different positions in the distance direction of the measured object with respect to the measurable range (claims 6 and 8).

[0013]

In the above arrangement, the first measurement condition and the second
Measurement conditions (in claims 1 and 3, the first distance condition and the second
Distance condition), when the actual measured distance is within the measurable range of the optical distance detecting means,
The difference between the first measurement result and the second measurement result should correspond to the difference between the measurement conditions. Therefore, these first
By monitoring the measurement result of the second measurement result
Appropriateness of the measurement result can be determined, and an appropriate final measurement result can be obtained.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS.

The non-contact type shape measuring apparatus shown in FIG. 3 has a bed 10 on which an X-axis guide member 11 extending in the X-axis direction (the depth direction in the drawing) is fixed. An X-axis table 12 is provided on the X-axis guide member 11 so as to be slidable along the X-axis guide member 11. The X-axis table 12 is slidably driven by an X-axis drive motor (scanning means) 14. . This X-axis table 1
On Y, a Y-axis guide member 16 extending in the Y-axis direction (the left-right direction in FIG. 3) is fixed, and a Y-axis table 20 is slidably mounted along the Y-axis guide member. The slide drive is performed by a shaft drive motor (scanning means) 18. On the Y-axis table 20, a Z-axis table 22 on which the object to be measured W is placed is set up and down (movable in the Z-axis direction). (Driving means) 23. That is, the X-axis drive motor 14 and the Y-axis drive motor 18 cause the Z
The object W to be measured placed on the axis table 22 is X, Y, Z
In each axial direction.

The apparatus has an X-axis scale 24 for detecting the amount of movement of the X-axis table 12 from the reference position, a Y-axis scale 26 for detecting the amount of movement of the Y-axis table 16 from the reference position, and a reference position. Z-axis scales 28 for detecting the amount of movement of the Z-axis table 22 from are provided. These scales 24, 26, 28 need only be able to detect the amount of movement of each axis table 12, 20, 22. A device that detects the amount of rotation with a potentiometer, a device that outputs a voltage corresponding to the pressure-sensitive scale pressing position, and the like are preferable. In addition, each axis drive motor 14,
When each of the motors 18 and 23 includes a stepping motor or the like, the moving distance may be obtained from the number of pulses of the drive signal.

On the other hand, a gate-shaped frame 29 is installed on the bed 10 so as to surround the periphery of the optical distance sensor 3.
It is mounted so as to be able to turn around a vertical axis with 0 facing downward.

This optical distance sensor 30 detects the distance to the surface of an object using a triangulation method. As shown in FIG. 4, a light emitting element 32 composed of a semiconductor laser or the like, a light projecting lens 34, a light receiving lens 36, and a light position detecting element (light receiving element) 38. Light emitting element 32
Are arranged in a direction of irradiating light vertically downward (along the Z-axis), and the light position detecting element 38 has a light-receiving area extending in a direction inclined with respect to a horizontal plane. Then, a point P on the surface of the device under test W is irradiated with light from the light emitting element 32 through the light projecting lens 34, and the reflected light is received by the light position detecting element 38 through the light receiving lens 36. (Strictly speaking, the peak position of the received light amount) is detected. Here, when the point P moves up and down to the points P1 and P2 in FIG. 4, the light receiving position of the light position detecting element 38 changes. The distance can be calculated.

In the present invention, the optical distance sensor 3
Regardless of the specific configuration of 0, various devices that measure the distance to the surface to be measured in a non-contact manner using reflected light can be applied.

This shape measuring device is provided with an arithmetic and control unit 40 as shown in FIG. As shown in the figure, detection signals and the like from the light position detection element 38 and the axis scales 24, 26, 28 are input to the arithmetic and control unit 40. The arithmetic and control unit 40 outputs a drive control signal to each of the axis drive motors 14, 18, and 23, and outputs a shape measurement result to a display device 52 such as a printer for external display. Has become.

The feature of this device is that the arithmetic and control unit 40
Is drive control means (transfer control means) 4 as shown in FIG.
2, a detection value comparing means (determining means) 44 and a shape calculating means 46 are provided.

The drive control means 42 includes the optical distance sensor 3
The object W is moved (scanned) by a unit distance in a direction perpendicular to the optical axis (ie, in the X-axis direction and the Y-axis direction) with respect to 0, and at each measurement point, the object W
Is moved between a predetermined first measurement position and a second measurement position separated from the first measurement position in the optical axis direction (Z-axis direction) (contact with the optical distance sensor 30). To separate them) so as to control the driving of the respective axis drive motors 14, 18, and 23.

The detected value comparing means 44 calculates the distance s at each measurement point at the first measurement position (ie, the distance from the optical distance sensor 30 to the light irradiation point on the object W) s
And a difference (s−) between the distance s ′ detected at the second measurement position.
s '), and based on the principle described later, whether or not the current detection value is valid is determined based on the difference (s-s'). Is to input the detected value to the shape calculating means 46, and when it is determined that the measured value is not valid, send a command to the drive control means 42 to move the workpiece W again in the Z-axis direction.

The shape calculating means 46 is provided for each axis scale 24,
The surface shape of the measured object W is calculated based on the transfer position of the measured object W obtained from the detection results 26 and 28 and the detected value determined to be valid by the detected value comparing means 44, and the result is calculated. Is displayed on the display device 52.

Next, the procedure of shape measurement by this apparatus is shown in FIG.
This will be described with reference to the flowchart of FIG.

First, the Z-axis table 22 shown in FIG.
An object to be measured W is set at a predetermined upper position (step S
1). Then, by appropriately operating the X-axis drive motor 14 and the Y-axis drive motor 18, the optical distance sensor 3
The device under test W is relatively moved by a unit distance in a direction perpendicular to the optical axis with respect to 0 (step S2). By this operation, each point on the workpiece W separated by a unit distance from each other is sequentially positioned at the measurement position (light irradiation position).

At each measurement point, first, the distance s from the optical distance sensor 30 to the surface of the workpiece W at the first measurement position.
Is detected (step S3), and the Z-axis drive motor 2
3 is operated to move the device under test W from the first measurement position to a second measurement position separated by a fixed measurement distance (step S4). The distance s' to a point on the surface of the workpiece W is detected (step S5). Then, the difference between the two distances (s−
Based on s '), it is determined whether the current distance detection values s and s' are valid values (step S6).

The principle is as follows. At the first measurement position, as shown in FIG. 6, the height distance (the distance detected by the Z-axis scale 28) from the reference position (zero position) in the Z-axis direction to the upper surface of the Z-axis table 22 is p, The distance (fixed value) from the zero position to the zero point position of the optical distance sensor 30 is a, and the distance from the zero point position of the optical distance sensor 30 to the light irradiation point on the workpiece W (that is, the optical type). Assuming that s is the distance detected by the distance sensor 30 and h is the height from the upper surface of the Z-axis table 22 to the light irradiation point on the workpiece W, the following relational expression holds.

[0029]

## EQU1 ## where p is positive when the upper surface of the Z-axis table 22 is below the zero point, and s is positive when the measurement point is below the zero point position of the sensor.

Next, at the second measurement position where the Z-axis table 22 and the object to be measured W are integrally lifted by a certain distance (for example, 1000 μm) from the first measurement position, the Z-axis is detected by the Z-axis scale 28. Assuming that the height distance of the Z-axis table 22 is p ′ and the distance detected by the optical distance sensor 30 is s ′, the point on the workpiece W is within the measurable range of the optical distance sensor 30 (ie, When the normal distance detection is performed by the optical distance sensor 30), the following expression is established.

[0031]

S−s ′ = p−p ′ = 1000 (μm) Therefore, if the measurement allowable error of the optical distance sensor 30 is α, the value (s−s ′) is 1000 ± α (μm). If it is within the allowable range, the measurement point is within the measurable range, that is, it can be determined that the detected values s and s' are valid. You can do it.

If the value (ss') is not within the allowable range (NO in step S6), the object W is moved by a predetermined adjustment distance in the Z-axis direction, and The measurement point on the surface of the measurement object is made to fall within the measurable range of the optical distance sensor 30 (step S7), and the processing from step S3 is performed again. At this time, the moving direction of the workpiece W may be determined based on the positive or negative of the detection distances s, s '. For example, when the s, s' is negative, the workpiece W may be lowered. Good.

If the value (ss') falls within the allowable range (YES in step S6), it is determined that the current detection value is valid and is taken into the shape calculation means 46 (step S8). Then, the operations after step S2 are executed until scanning (scanning in the X-axis direction and Y-axis direction) is completed (NO in step S9), and after the scanning is completed, the shape is determined based on only the data taken as valid. Is calculated and displayed on the display device 52.

As described above, in this apparatus, detection is performed by the optical distance sensor 30 at two measurement positions separated from each other in the Z-axis direction at each measurement point, and the difference between the detected values (s
−s ′), it is determined whether this detection is valid, that is, whether the measurement point is within the measurable range of the optical distance sensor 30. Even if there is a large step on the surface of W, the validity of the detected value can be accurately determined, and thereby accurate shape measurement can be realized.

FIG. 7 is a graph showing the relationship between the relative distance of the object W to the actual optical distance sensor 30 and the value detected by the optical distance sensor 30. As is apparent from this figure, when the actual distance s is out of the range of ± 6 mm with respect to the zero point of the sensor, the optical distance sensor 3
Detection by 0 is virtually impossible.

FIG. 9A shows the shape data obtained when all the measured values are taken in ignoring the measurable range of the optical distance sensor 30 as described above, and FIG. 9B shows the present embodiment. FIG. 9 schematically shows data obtained when detection is performed twice at each measurement point to determine the validity of a detection value as in the example. As shown in FIG. 9B, according to the present embodiment, the shape of the actual object to be measured can be accurately grasped. On the other hand, as shown in FIG. Satisfactory shape data can hardly be obtained due to the inability to deal with undulations. This result clearly shows the usefulness of the apparatus of this embodiment.

In the above embodiment, the object to be measured W is moved, but the optical distance sensor 30 may be moved while the object to be measured W is kept still.

[0038]

As described above, according to the present invention, each measurement position is measured under two different conditions, and based on a comparison of these measurement results, it is determined whether or not the measurement result is valid. In addition, since the final measurement result is obtained, even if there is a large step on the surface of the object to be measured, the validity of the measurement value can be accurately determined, and accurate non-contact shape measurement can be performed. There is an effect that can be realized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a main part of an arithmetic and control unit provided in a non-contact type shape measuring apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing input / output signals of the arithmetic and control unit.

FIG. 3 is a front view of the non-contact type shape measuring device.

FIG. 4 is a configuration diagram of an optical distance sensor provided in the non-contact type shape measuring device.

FIG. 5 is a flowchart showing a measuring procedure by the non-contact type shape measuring apparatus.

FIG. 6 is an explanatory diagram showing a positional relationship between an optical distance sensor and an object to be measured in the non-contact type shape measuring device.

FIG. 7 is a graph showing a relationship between an actual relative distance between the optical distance sensor and an object to be measured, and a distance detected by the optical distance sensor.

8A is a diagram showing shape data created by a conventional device, and FIG. 8B is a diagram showing shape data created by a device of the present invention.

FIG. 9 is an explanatory diagram showing a measurable range of the optical distance sensor.

[Explanation of symbols]

 14 X-axis drive motor (scanning means) 18 Y-axis drive motor (scanning means) 23 Z-axis drive motor (contact / separation means) 30 Optical distance sensor (optical distance detecting means) 32 Light emitting element 38 Light position detecting element (light receiving) Element) 40 arithmetic control unit 42 drive control means 44 detected value comparison means (judgment means) 46 shape calculation means

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01B 11/00-11/30 102

Claims (8)

(57) [Claims] A light-emitting member for irradiating the surface of the object with light; a light-receiving member for receiving light emitted from the light-emitting member and reflected from the surface of the object; and an output of the light-receiving member. Means for determining a distance to each position on the surface of the object based on the first position .
Means for obtaining a final measurement result based on a first measurement result obtained by performing the measurement under the distance condition and a second measurement result obtained by performing the measurement under the second distance condition. A non-contact type shape measuring device, comprising: 2. The non-contact type shape measuring apparatus according to claim 1,
In the first distance condition and the second distance condition,
A non-contact shape measuring device, wherein a distance of an object to be measured to at least one of the light emitting member and the light receiving member is different. 3. A light-emitting member for irradiating light to the surface of the object, a light-receiving member for receiving light emitted from the light-emitting member and reflected from the surface of the object, and an output of the light-receiving member. Means for determining a distance to each position on the surface of the object based on the first position .
Is determined based on a first measurement result obtained by performing the measurement under the second distance condition and a second measurement result obtained by performing the measurement under the second distance condition. Non-contact type shape measuring device characterized by comprising means. 4. A non-contact type shape measuring apparatus according to claim 3.
When the distance obtained by the measurement under the first distance condition and the distance obtained by the measurement under the second distance condition are within a predetermined range, it is determined that the measurement result is appropriate. A non-contact type shape measuring device, characterized in that: 5. A light-emitting member for irradiating light to the surface of the object, a light-receiving member for receiving light emitted from the light-emitting member and reflected from the surface of the object, and an output of the light-receiving member. Means for determining a distance to each position on the surface of the object based on the first position.
Means for obtaining a final measurement result based on the first measurement result obtained by performing the measurement under the measurement conditions of the above and the second measurement result obtained by performing the measurement under the second measurement condition. A non-contact type shape measuring device, comprising: 6. A non-contact shape measuring apparatus according to claim 5,
In the first measurement condition and the second measurement condition,
A non-contact type shape measuring device characterized in that the position of an object to be measured with respect to a measurable range is different. 7. A light-emitting member that irradiates light to the surface of the object, a light-receiving member that receives light emitted from the light-emitting member and reflected from the surface of the object, and an output of the light-receiving member. Means for determining a distance to each position on the surface of the object based on the first position.
Judge the suitability of the measurement result based on the first measurement result obtained by performing the measurement under the second measurement condition and the second measurement result obtained by performing the measurement under the second measurement condition. Non-contact type shape measuring device characterized by comprising means. 8. The non-contact shape measuring device according to claim 7,
In the first measurement condition and the second measurement condition,
A non-contact type shape measuring device characterized in that the position of an object to be measured with respect to a measurable range is different.