JP3434425B2 - 3D 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 a three-dimensional shape measuring apparatus used for measuring the shape of an object to be measured having a three-dimensional shape in a non-contact state using laser light.

[0002]

2. Description of the Related Art A three-dimensional shape measuring device of this type is disclosed, for example, in Japanese Unexamined Patent Publication No. 7-113637. The device of the publication includes a reception signal processing circuit and a calibration data memory for each sensor on the sensor head side provided with a laser light source and a plurality of sensors, and enhances connection compatibility between the sensor and the controller for measurement. We are trying to prevent a decrease in precision.

[0003]

However, in the conventional measuring device as described above, when the object to be measured is a mass-produced product, the measurement signal is processed by referring to the preset calibration data, Although it is possible to prevent a decrease in accuracy in signal processing, the object to be measured is not a mass-produced product, and individual shapes are different, such as a tooth model or tooth mold for manufacturing a dental prosthesis, and surface materials are different. Therefore, when the objects to be measured have different reflectance characteristics, there is a problem that it is not possible to sufficiently prevent the deterioration of the measurement accuracy with only several kinds of calibration data set in advance. That was the challenge.

In this type of measuring device, for example, if the filter glass or optical lens of the light receiving system is slightly dirty or water droplets are attached, the amount of light received by the sensor changes and the output becomes delicate. Because of the change, the measurement distance may have an error even when using the calibration data set in the condition that the optical system is clean. In addition to this, the characteristic change of the optical position detection element due to the temperature change and the minute change due to the temperature expansion may occur. Even if the optical system is changed, an error may occur in the measurement distance.

Further, for example, in measuring the shape of a dental mold for producing a dental prosthesis, the difference in the color and concentration of the pigment in the plaster material used for the dental mold, the unevenness of the material due to the non-uniform mixing of the materials, Alternatively, there may be a difference in the surface reflectance characteristics of the tooth mold depending on the presence or absence of minute surface irregularities on the tooth mold. Therefore, when measuring the shape of a tooth model or tooth model for producing a dental prosthesis, the above-mentioned various factors are complicatedly related, and the measurement conditions change delicately at each measurement. There is a problem in that it is not possible to perform highly accurate shape measurement only with the calibration data of.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and is capable of performing highly accurate shape measurement even when the shape of each measured object or the reflectance characteristic of the surface is different. It is an object of the present invention to provide a three-dimensional shape measuring device that can perform measurement.

[0007]

A three-dimensional shape measuring apparatus according to the present invention is, as a first aspect, a triangulation method in which a light projecting system including a laser light source and a light receiving system including an optical position detecting element are combined. Detects the amount of movement in each axial direction of the distance measuring means for measuring the distance to the object to be measured, and the multi-axis moving means for changing the relative position of the distance measuring means and the object to be measured in three axial directions. In the apparatus for measuring the three-dimensional shape of the object to be measured, which is provided with the moving position detecting means, the direction in which the distance measuring means and the object to be measured approach and separate is defined as the Z axis direction, and the distance measuring means and the object to be measured are moved by the multi-axis moving means. From the distance data when the distance measuring means measures an arbitrary calibration point of the measured object while changing the distance in the Z-axis direction to the measured object, and the moving position data of the moving position detecting means in the Z-axis direction Calibration hand to detect the calibration data represented And a received light amount detecting means for detecting the received light amount from the output of the optical position detecting element of the distance measuring means, and a received light amount detected by the received light amount detecting means when the measuring data is detected by the measuring means within a preset range. The distance measuring means is provided with a received light amount determining means for determining whether or not there is a light receiving amount determining means, and the distance measuring means performs control to calibrate the distance data when the main measurement is performed. A plurality of light receiving systems are provided at axially symmetrical positions about the light projecting axis, and the calibration means is a means for detecting calibration data for each light receiving system. In the three-dimensional shape measuring device, the light receiving amount detecting means for detecting the light receiving amount from the output of each light receiving system of the distance measuring means and the selecting means for comparing the light receiving amount by each light receiving system and selecting the largest light receiving amount. Equipped, the amount of received light is selected It was has been configured to perform control to calibrate with calibration data and the distance data of the measurement detected by the calibration unit obtained by the light receiving system, and a means for solving the problems of the above configuration.

A three-dimensional shape measuring apparatus according to the present invention is, in claim 4, an object to be measured by a triangulation method by combining a light projecting system including a laser light source and a light receiving system including an optical position detecting element. Position detecting means for measuring the distance to the object and moving position detecting means for detecting the amount of movement in each axial direction of the multi-axis moving means for changing the relative positions of the distance measuring means and the object to be measured in three orthogonal directions. In the device for measuring the three-dimensional shape of the object to be measured, the direction in which the distance measuring means and the object to be measured approach and separate is defined as the Z-axis direction, and the distance measuring means and the object to be measured are moved by the multi-axis moving means. Calibration data representing a mutual relationship is obtained from the distance data when the distance measuring means measures an arbitrary calibration point of the measured object while changing the distance in the Z-axis direction and the movement position data of the movement position detecting means in the Z-axis direction. Equipped with a calibration means to detect, The separation measuring means selects a plurality of sets of light receiving systems having different light receiving angles with one set of a plurality of light receiving systems arranged symmetrically about the projection axis of the laser light, and a switching means for selecting an output from each set. In addition, the calibration means is a means for detecting calibration data for each light receiving system, and is configured to perform control to calibrate the distance data when the main measurement is performed by the distance measuring means with the calibration data. It is used as a means to solve the problem.

[0009]

In the three-dimensional shape measuring apparatus according to the first aspect of the present invention, the direction in which the distance measuring means and the object to be measured come close to and apart from each other is defined as the Z-axis direction, and the measuring means moves the distance by the multi-axis moving means. From the distance data and the moving position data of the moving position detecting means in the Z-axis direction when the distance measuring means measures an arbitrary calibration point of the measured object while changing the distance between the measuring means and the measuring object in the Z-axis direction. Detecting the calibration data representing the mutual relationship, after this, when the main measurement by the distance measuring means, because the control to calibrate the distance data with the calibration data is performed,
Even if the shape and surface reflectance characteristics of individual DUTs are different, each time the shape of the DUT is measured, the calibration data of the DUT itself is used to calibrate the distance data. As a result, highly accurate measurement results can be obtained. Further, in the measuring device, when the received light amount is within the set range by detecting the received light amount by the received light amount detection means and determining whether the received light amount is within the set range by the received light amount determining means, It can be judged that the normal measurement is being performed, and when the received light amount is outside the setting range,
It can be judged that there is some trouble in the light receiving system or the DUT side.

In the three-dimensional shape measuring apparatus according to the second aspect of the present invention, the distance data is obtained from each of the plurality of light receiving systems in the distance measuring means, and the calibration data is detected for each light receiving system in the calibration means. , Multiple calibration data used for calibration will be obtained, or even if the reflected light does not enter a part of the light receiving system due to the surface shape of the object to be measured, etc., the remaining light receiving system will obtain the distance data. Accordingly, the accuracy of shape measurement or the reliability of the measurement function can be improved.

[0011]

In the three-dimensional shape measuring apparatus according to the third aspect of the present invention, the light receiving detecting means detects the respective light receiving amounts from the outputs of the plurality of light receiving systems of the distance measuring means, and the selecting means gives the largest light receiving amount. The control is performed to calibrate the distance data of the main measurement obtained by the selected light receiving system with the selected light receiving system using the calibration data detected by the calibration device. Even if there is a difference in reflectance characteristics on a part of the surface of the object to be measured, highly accurate shape measurement can be performed without being affected by these differences.

In the three-dimensional shape measuring apparatus according to the fourth aspect of the present invention, the direction in which the distance measuring means and the object to be measured approach and separate is defined as the Z-axis direction, and the measuring means uses the multi-axis moving means to measure the distance. And the object to be measured while varying the distance in the Z-axis direction from the distance data when measuring an arbitrary calibration point of the object to be measured by the distance measuring means and the moving position data in the Z-axis direction of the moving position detecting means. When the calibration data that represents the relationship is detected and then the distance measurement means performs the main measurement, the calibration is performed to calibrate the distance data, so when the shape and surface reflectance characteristics of each measured object are different. However, each time the shape of the object to be measured is measured, the calibration data of the object to be measured is used to calibrate the distance data, whereby a highly accurate measurement result can be obtained. Further, in the measuring device, since the distance data is obtained from each of the plurality of light receiving systems in the distance measuring means, and the calibration data is detected in each of the light receiving systems in the calibration means, a plurality of calibration data used for calibration is obtained. Or, even if the reflected light is not incident on a part of the light receiving system due to the surface shape of the object to be measured, the distance data can be obtained by the remaining light receiving system. Can improve the sex. Further, in the measuring device, the distance measuring means includes a plurality of sets of light receiving systems having different light receiving angles and a switching means of each set. Therefore, it is possible to select an optical system at a position that does not cause a blind spot.

[0014]

[0015]

[0016]

[0017]

According to the three-dimensional shape measuring apparatus according to the first aspect of the present invention, even when the shape or the surface reflectance characteristic of each measured object is different, it is possible to measure the shape of the measured object. Since the calibration of the distance data is performed each time using the calibration data of the measured object itself, each measured object such as a tooth model or a tooth mold for manufacturing a dental prosthesis is measured. Even if the shape and the reflectance characteristics of the surface are different, it is possible to accurately measure the shape of any object to be measured,
Highly accurate measurement results can be obtained. Further, according to the measuring device, it is possible to determine whether or not normal measurement is performed by determining whether or not the amount of received light is within the set range before the main measurement. When the amount of received light is out of the setting range, it is possible to determine the occurrence of problems such as contamination of the optical system, the influence of the material of the measured object, the position error of the calibration point, or the poor placement of the measured object. , It is possible to prevent the measurement failure.

According to the three-dimensional shape measuring apparatus of the second aspect of the present invention, the same effect as that of the first aspect can be obtained, and a plurality of calibration data used for calibration can be obtained, so that the measurement target can be measured. It is possible to achieve higher accuracy in measuring the shape of an object, or even if reflected light does not enter part of the light receiving system due to the surface shape of the object to be measured, distance data can be obtained from the remaining light receiving system. Therefore, the reliability of the measurement function can be improved.

[0019]

According to the three-dimensional shape measuring apparatus of the third aspect of the present invention, the same effect as that of the second aspect can be obtained, and the largest amount of received light is detected for the plurality of light receiving systems. Since the distance data of the actual measurement obtained by the light receiving system is calibrated with the calibration data, it is assumed that some optical systems have slight stains or there is a difference in the reflectance characteristics on the surface of the DUT. Even if there is a change in the temperature characteristics of the light receiving system, it is possible to perform highly accurate shape measurement without being affected by these.

According to the three-dimensional shape measuring apparatus of the fourth aspect of the present invention, even when the shape or surface reflectance characteristic of each measured object is different, each time the shape of the measured object is measured. Since the distance data is calibrated using the calibration data of the measured object itself, the shape of each measured object such as the measured model such as a tooth model or a tooth mold for manufacturing a dental prosthesis is measured. Even if the reflectance characteristics of the surface is different, it is possible to accurately measure the shape of any object to be measured,
Highly accurate measurement results can be obtained. Further, according to the measuring device, a plurality of calibration data used for calibration can be obtained, so that the accuracy of shape measurement of the object to be measured can be further improved, or the surface shape of the object to be measured can be more accurate. Even when the reflected light does not enter the light receiving system of the part, since the distance data can be obtained by the remaining light receiving systems, the reliability of the measuring function can be improved. Further, according to the measuring device, even if the object to be measured has a deep recess, for example, by selecting an optical system at a position that does not form a blind spot with respect to the reflected light, a highly accurate shape can be obtained without any problem. Measurement can be performed, and if a failure occurs in one optical system, it can be quickly switched to another optical system as a backup means.

[0022]

[0023]

[0024]

[0025]

1 to 9 are views for explaining an embodiment of a three-dimensional shape measuring apparatus according to claims 1 to 3 of the present invention.

As shown in FIG. 1, the three-dimensional shape measuring device is a distance measuring means (sensor head) 1 using laser light.
The control device 2 and the stage 3 for setting the three-dimensionally measured object M are provided, and the control device 2 is connected to the display device 4 for displaying the measurement results and the like. The object M to be measured in this example is a tooth model (abutment) for manufacturing a dental prosthesis.

The measuring device comprises a Z-axis driving device 5 for driving the distance measuring means 1 closer to and away from the object to be measured M on the lower side, that is, an XY-axis for moving the stage 3 in two horizontal axial directions. The drive device 6 is provided, and the Z-axis drive device 5 and X
With the Y-axis drive device 6, the distance measuring means 1 and the object to be measured M are measured.
It constitutes a multi-axis moving means for changing the relative position with respect to three directions of X, Y and Z which are orthogonal to each other. Each drive 5,
6 is provided with movement position detecting means 7 and 8 for detecting movement amounts in the Z-axis direction and the XY-axis direction.

The distance measuring means 1 comprises a laser diode 9a.
And a light projecting system L including a laser light source 9 including its driving circuit 9b, and two light receiving systems R1 and R2 including optical position detecting elements 10a and 10b. The light projecting system L includes a laser light source 9 and a light projecting lens 11. On the other hand,
The two light receiving systems R1 and R2 are arranged at axially symmetrical positions about the projection axis of the irradiation laser beam LT and at the same light receiving angle, and in addition to the light position detecting elements 10a and 10b, a light receiving lens. 12a, 12b and the light receiving filter 13a,
13b is provided. In addition, each optical position detection element 10a,
The 10b is provided with I / V conversion circuits 14a and 14b for converting the current output from the same element into a voltage.

The distance measuring means 1 emits the irradiation laser beam LT from the light projecting system L toward the object to be measured M, and the reflected laser beam LR from the object to be measured M is received by each of the light receiving systems R1 and R2. Based on the position and the light receiving angle of each of the light receiving systems R1 and R2, the light receiving positions of the light position detecting elements 10a and 10b, and the like, the object M to be measured is triangulated.
The distance to is measured.

The control device 2 includes each I / V conversion circuit 14a,
14b voltage signals (V1, V2) a, (V1, V
2) An amplifier 15 for amplifying b, an A / D conversion circuit 16 for converting an analog signal output from the amplifier 15 into a digital signal, and an output from the A / D conversion circuit 16 for each of the optical position detection elements 10a and 10b. The calculation circuit 17 is provided for calculating the characteristic value Vs proportional to the position of the light receiving point.
The characteristic value Vs is (V1-V2) / (V1 + V2).
The control device 2 then outputs the output value (V
s) That is, from the distance data when the distance to the object M is measured by the distance measuring means 1 and the moving position data from the moving position detecting means 7 in the Z-axis direction, the calibration data representing the mutual relationship is detected. A calibration means 18 is provided.

Further, the control device 2 includes an A / D conversion circuit 16
A light receiving amount detecting means 19 for detecting the light receiving amount (V1 + V2) from the outputs of the optical position detecting elements 10a and 10b of the distance measuring means 1 is connected to the light receiving amount detecting means 19 and the light receiving amount detected by the light receiving amount detecting means 19 is preset. The light receiving amount determining means 20 for determining whether or not the light receiving amount is within the range is provided, and each light receiving system R is provided between the calibration means 18 and the light receiving amount detecting means 19.
The selection means 21 is provided for comparing the received light amounts of 1 and R2 and selecting the larger received light amount.

Next, the operation of the three-dimensional shape measuring apparatus having the above configuration will be described with reference to the flow charts shown in FIGS.

FIG. 2 is a flow chart schematically showing the shape measuring process. In step S01, the object to be measured M is attached to the stage 3, and then the calibration curve acquisition step S10 for detecting the calibration curve is performed. In step S40, a sensor for displaying whether or not there is a defect in the calibration curve data, and if there is a defect, returns to before mounting the object to be measured M, and if there is no defect, a sensor for setting the position of the distance measuring means 1 Proceeding to the height setting step S20, the main measurement of the measured object M is performed in the XYZ measurement step S30.

In the calibration curve acquisition step S10, as shown in FIG. 3, after the object to be measured M is attached, in step S11, the stage 3 is moved in the X and Y axis directions to measure the object to be measured M with respect to the distance measuring means 1. Specify any calibration point of.

Next, in step S12, the distance measuring means 1 is moved in the Z-axis direction (vertical direction) in minute steps, and the distance to the calibration point is measured for each step. In step S13, the received light amount is detected. The light position detecting elements 10a and 10b of the light receiving systems R1 and R2 are provided by the means 19.
Of the received light amount (V1 + V2) is detected, and in step S14, the received light amount determination means 20 determines whether or not the received light amount is within a preset range A1 to A2.

When the amount of received light is within the set range in step 14S (Yse), in step S15 the arithmetic circuit 17 determines the light receiving points of the light position detecting elements 10a and 10b from the outputs of the respective light receiving systems R1 and R2. The characteristic value Vs that is proportional to the position of is calculated for each step in the Z-axis direction, and in step S16, the calibration means 18
Calibration curve data, which is correspondence data between the characteristic value Vs, which is distance data, and the movement position data from the movement position detecting means 7 in the Z-axis direction is detected. In the above process, the distance measuring means 1 is moved stepwise in the Z-axis direction and the distance to the object M to be measured is measured at each step, so the calibration data becomes calibration curve data.

If the amount of received light is out of the set range in step S14 (No), the number of consecutive times out of the range is determined in step S19, and the number of consecutive times is equal to or less than the preset number (N times). In the case of (No), the calibration point is determined to be defective and the measurement of the calibration point is repeated from step S12. When the number of consecutive times exceeds the set number of times (Yes), the light receiving diameters R1 and R2 are defective in step S40. Is displayed, and it is determined that the workpiece M is not properly attached, and the procedure returns to before the attachment of the object M to be measured. In addition,
The reason why the amount of received light (V1 + V2) is outside the specified range A1 to A2 will be described in detail later.

In the sensor height setting step S20, after the previous calibration curve data is detected, in step S21 the height which is the position of the distance measuring means 1 in the Z-axis direction is tentatively determined, and then the XY-axis driving means. 6, the representative shape of the object to be measured M is sampled and measured while moving the stage 3 in a horizontal direction at a coarse pitch, the characteristic value Vs which is the distance data at each point is obtained in step S22, and previously obtained in step S23. The provisional distance data group in the Z-axis direction is detected in step S24 with reference to the calibration curve data. Then, in step S25, from the provisional distance data group, for example, the average value becomes the median value of the calibration curve data, or the measured object M is the focal position (spot) of the irradiation laser beam LT from the projection system L. An appropriate height of the distance measuring means 1 is set so that the diameter becomes smaller).

The laser spot diameter increases as it deviates from the focus position, and if the spot diameter increases, fine point measurement cannot be performed, resulting in a decrease in accuracy. Therefore, as described above, the distance measuring means 1 has a high height. The accuracy can be maintained by setting the height.

In XYZ measurement step S30, after the height of the distance measuring means 1 is finally determined in step S31, the object M to be measured is actually measured while moving the stage 3 in the XY axis directions at a fine pitch. In S32, the received light amount detecting means 19 detects the received light amounts (V1 + V2) a and b by the respective light receiving systems R1 and R2 at each XY position, and in step S33, the selecting means 21 compares the two received light amounts, In S34, the larger light receiving amount is selected by the selecting means 21.

That is, when the object M to be measured has a truncated cone shape as shown in FIG. 1, the irradiation laser beam LT is applied to the left side surface m.
Is illuminated, the light receiving system R2 on the right side becomes a blind position. At this time, in the measuring device, the light receiving amount of the right light receiving system R2 is significantly reduced,
It is determined that 2 has become the blind position, and the light receiving system R1 on the left side is automatically selected.

Then, in step S35, the characteristic value Vs, which is distance data, is detected using the output from the light receiving system that has obtained a large amount of received light, and in step S36, the previously detected light receiving systems R1 and R2 are detected. From the calibration curve data using the output, select the calibration curve data using the output from the light receiving system that has obtained a large received light amount, and in step S37, calibrate the distance data obtained in the main measurement with the selected calibration curve data. To do. Further, the selection of the light receiving system according to the selection of the light receiving amount in step S34 is repeated for each movement pitch of the stage 3, and in step S38, the distance data in the Z-axis direction calibrated by the calibration curve data and the movement position detecting means 8 are used. XY
The XYZ data group, that is, the three-dimensional shape data of the measured object M is detected from the axial movement position data, and the measurement is completed.

As described above, in the above-described three-dimensional shape measuring apparatus, basically, even when the shape or surface reflectance characteristic of each measured object M is different, the shape measurement of the measured object M is performed. Each time, the calibration data of the object to be measured is used to calibrate the distance data, so that highly accurate shape measurement can be performed, and if some optical systems are slightly soiled,
There is a difference in reflectance characteristics on a part of the surface of the object to be measured M,
Alternatively, even if there is a change in the temperature characteristic of the light receiving system, these effects are not affected.

Moreover, in the above-mentioned three-dimensional shape measuring apparatus, the calibration curve data is detected by changing the distance between the distance measuring means 1 and the object to be measured M in the Z-axis direction at regular steps. Since it is used for calibration, it is possible to improve the accuracy of the subsequent sampling measurement and main measurement results. Furthermore, the calibration curve data is used to perform the sampling measurement of the measured object M, and the distance data Since the height of the distance measuring means is determined on the basis of the distance measurement means 1 and the object to be measured M so that the laser spot diameter becomes small in order to perform accurate point measurement before performing the main measurement.
The distance between and is set appropriately.

Further, in step S14 of the calibration curve acquisition step S10, the cause that the amount of received light (V1 + V2) is out of the specified range A1 to A2 is the excessive or insufficient amount of reflected light on the surface of the object M to be measured. To be

The tooth model, which is the object M to be measured as shown in this embodiment, is usually formed by mixing a plaster material with a pigment, and the surface reflectance thereof is as shown in FIG. It is almost a function of cosine with respect to the light receiving angle. That is, when the laser spot is in a state close to ideal diffuse reflection and the plane is vertically irradiated, and the light is received at an inclination of the angle θ, the amount of light received by the optical position detection elements 10a and 10b is proportional to the characteristic value of FIG.

In the case of a plaster material having a high reflection intensity (for example, a light pink color), the ghost intensity due to the secondary reflection light is also large, and an error is likely to occur when this light is received. Therefore, the received light amount is within the setting range A1 to A2. Only when it is less than or equal to the upper limit A2 of.

On the other hand, in the case of a gypsum material having a low reflection intensity (for example, black), the primary reflected laser light LR itself becomes weak,
When the amount of light received by the light position detecting elements 10a, 10b decreases, the dark current of the light position detecting elements 10a, 10b relatively increases and an error occurs. Therefore, when the amount of light received exceeds the lower limit A1 of the setting range A1 to A2. Only if there is one.

In addition, the reason why the amount of received light (V1 + V2) is out of the specified range A1 to A2 is that one of the light receiving systems becomes dirty and the amount of received light becomes less than the lower limit A1 of the set range A1 to A2, or As shown in 7, the object to be measured (tooth model) M
There is a trace h of air bubbles mixed in during the plaster production on the surface of
There is a case where the irradiation laser beam LT is applied to this. In the case of the state shown in FIG. 7, the amount of light received by one of the light receiving systems may not fall within the set range.

Since all of the above problems impair the accuracy of shape measurement, it is determined in step S19 that the amount of received light does not fall within the set range N times in a row, and this causes problems. Is displayed.

Further, although the received light amount is within the set range, the received light amount may differ between the two light receiving systems R1 and R2. The cause is that the calibration point is measured as shown in FIG. The case where it is designated as the inclined surface of the object M is mentioned.
When the calibration point is on the inclined surface having the angle φ, the light receiving angle in each of the light receiving systems R1 and R2 changes by the angle φ, as shown in FIG. 9, and the respective light receiving amounts differ. That is,
When the light receiving amounts of the respective light receiving systems R1 and R2 are different,
Since it can be determined that there is a problem with the placement of the object to be measured M on the stage 3, the fact that a problem has occurred is also displayed in such a case. It should be noted that when the object M to be measured is significantly tilted, the side surface m of the object M to be measured may be a blind spot with respect to the projection axis of the irradiation laser beam LT. There is.

As described above, according to the measuring apparatus, the amount of received light is detected and selected, and before the main measurement, contamination of the optical system, the influence of the material of the object M to be measured, the position error of the calibration point, or the object to be measured. It is possible to determine the occurrence of a defect such as a defective placement of the device, and prevent measurement failure.

10 to 12 are views for explaining an embodiment of a three-dimensional shape measuring apparatus according to claim 4 of the present invention. The same components as those in the previous embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the three-dimensional shape measuring apparatus shown in FIG. 10, the distance measuring means 1 has a plurality of light receiving systems arranged axially symmetrically with respect to the projection axis of the irradiation laser beam LT as a set and has a light receiving angle of one set. A plurality of different sets of light receiving systems (R1 to R4) and switching means 30 for selecting the output from each set are provided.

Each light receiving system is composed of two light receiving systems R1 and R2 arranged symmetrically with respect to the light projecting axis, and two light receiving systems R3 and R4 provided at positions where the light receiving angle is smaller than these. It is divided into two groups. Each of the light receiving systems R1 to R4 includes light position detecting elements 10a to 10d, light receiving lenses 12a to 12d, light receiving filters 13a to 13d, and an I / V conversion circuit 14a.
.About.14d respectively.

The switching means 30 outputs the respective outputs (V1, V2) obtained by the pair of light receiving systems R1, R2 having the larger light receiving angle.
a, (V1, V2) b and respective outputs (V1, V2) c, obtained by the light receiving systems R3, R4 of the pair having the smaller light receiving angle.
(V1, V2) d is switched and sent to the control device 2 side, and can be selectively operated.

Generally, according to the triangulation principle, as shown in FIG. 11, the displacement δ of the light receiving point of the optical position detecting element 10 with respect to the displacement d of the height of the object M to be measured is more sensitive as the light receiving angle θ is larger. Is high. For this reason, the light receiving system is arranged so that the light receiving angle θ becomes large to some extent, but depending on the shape of the object M to be measured, a problem may occur due to the large light receiving angle θ.

That is, as shown in FIG.
If there is a narrow and deep recess H on the upper surface of the
The reflection angle α of R becomes small, and both of the pair of light receiving systems have 1
There may be a blind spot position where the secondary reflected laser light LR cannot be received. In this case, the secondary reflection is received by the light receiving system, but the light position detection element does not distinguish whether the reflected light is primary or secondary, and it receives light in an integrated manner to obtain data. Output. It is clear that such output data has a large error.

In order to cope with such a problem, in the measuring apparatus of this embodiment, the distance measuring means 1 is provided with two sets of light receiving systems R1 to R4 having different light receiving angles, and the switching means 30 makes it possible to select a set. Therefore, for example, in the case where the shape measurement is performed by the pair of light receiving systems R1 and R2 that normally have a large light receiving angle, and the object M to be measured has a recess H as shown in FIG.
By switching to the light receiving systems R3 and R4 of a small light receiving angle that can reliably receive the next reflected laser light LT, it is possible to perform measurement while maintaining high accuracy.

Further, since the switching means 30 is provided on the distance measuring means 1 side, it is not necessary to make any change related to the switching on the control device 2 side, and the shape measurement can be performed by the same data processing as in the previous embodiment. In addition, in the measuring apparatus of this embodiment, when a defect occurs in one set of light receiving systems, it is possible to quickly switch to another set of light receiving systems as a backup function.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of a three-dimensional shape measuring apparatus according to claims 1 to 3 of the present invention.

FIG. 2 is a flowchart schematically showing the operation of the measuring apparatus shown in FIG.

FIG. 3 is a flowchart showing in detail the calibration curve acquisition step shown in FIG.

FIG. 4 is a flowchart showing in detail the sensor height setting step shown in FIG. 2 subsequent to FIG. 3;

5 is a flowchart showing in detail the XYZ measurement steps shown in FIG. 2 subsequent to FIG. 4;

FIG. 6 is a graph showing a relationship between a light receiving angle of a light receiving system and a reflection intensity with respect to an object to be measured which is a tooth model made of gypsum material.

FIG. 7 is a side view for explaining a case where there are traces of air bubbles in the measured object, which is a tooth model made of gypsum material.

FIG. 8 is an explanatory diagram showing a state in which a placement error of an object to be measured has occurred.

FIG. 9 is a graph showing the relationship between the light receiving angle of the light receiving system and the reflection intensity when a calibration point is designated on the inclined surface.

FIG. 10 is an explanatory diagram showing an embodiment of a three-dimensional shape measuring apparatus according to claim 4 of the present invention.

FIG. 11 is an explanatory diagram showing the relationship between the height displacement of the object to be measured based on the triangulation principle, the displacement of the light receiving point in the light position detection element, and the light receiving angle of the light receiving system.

FIG. 12 is an explanatory diagram showing reflected laser light when there is a concave portion on the upper surface of the object to be measured.

[Explanation of symbols]

1 Distance measuring means 5 Z-axis drive (multi-axis moving means) 6 XY axis drive (multi-axis moving means) 7 Moving position detection means (in Z-axis direction) 8 Moving position detecting means (in XY axis directions) 9 Laser light source 10a 10b Optical position detection element 18 Calibration means 19 Light receiving amount detecting means 20 Light reception amount determination means 21 Selection means 30 switching means L light projection system M DUT R1 to R4 light receiving system

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Fumio Ueda 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Toshihiko Matsuda 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Sanko Co., Ltd. (56) Reference JP-A-2-116706 (JP, A) JP-A-3-167410 (JP, A) JP-A-2-115711 (JP, A) (58) Fields investigated ( Int.Cl. ⁷ , DB name) G01B 11/24 G01C 3/06 A61C 19/04

Claims (4)

(57) [Claims] 1. A distance measuring means for measuring a distance to an object to be measured by a triangulation method by combining a light projecting system including a laser light source and a light receiving system including an optical position detecting element, and the distance measuring means and the object to be measured. An apparatus for measuring a three-dimensional shape of an object to be measured, comprising moving position detecting means for detecting a moving amount in each axial direction of a multi-axis moving means for changing a relative position to an object in three orthogonal directions. The direction in which the distance measuring means and the object to be measured approach and separate is defined as the Z-axis direction, and the distance measuring means changes the distance in the Z-axis direction between the distance measuring means and the object to be measured by the distance measuring means. From the output of the optical position detection element of the distance measuring means and the calibration means for detecting the calibration data indicating the mutual relationship from the distance data when measuring an arbitrary calibration point and the movement position data of the movement position detecting means in the Z-axis direction. Received light amount detection to detect received light amount Means and a received light amount determination means for determining whether the received light amount detected by the received light amount detecting means when the calibration data is detected by the measuring means is within a preset range, and the main measurement is performed by the distance measuring means. A three-dimensional shape measuring device, characterized in that control is performed to calibrate distance data at the time with calibration data. 2. The distance measuring means is provided with a plurality of light receiving systems at axially symmetric positions around the projection axis of the laser light, and the calibration means is means for detecting calibration data for each light receiving system. The three-dimensional shape measuring apparatus according to claim 1, wherein 3. The three-dimensional shape measuring device according to claim 2, wherein the light receiving amount detecting means for detecting the light receiving amount from the output of each light receiving system of the distance measuring means is compared with the light receiving amount by each light receiving system. A three-dimensional shape characterized by comprising a selection means for selecting the largest amount of received light, and performing control to calibrate the distance data of the main measurement obtained by the light receiving system with the selected amount of received light with the calibration data detected by the calibration means. Measuring device. 4. A distance measuring means for measuring a distance to an object to be measured by a triangulation method by combining a light projecting system including a laser light source and a light receiving system including an optical position detecting element, and the distance measuring means and the object to be measured. An apparatus for measuring a three-dimensional shape of an object to be measured, comprising moving position detecting means for detecting a moving amount in each axial direction of a multi-axis moving means for changing a relative position to an object in three orthogonal directions. The direction in which the distance measuring means and the object to be measured approach and separate is defined as the Z-axis direction, and the distance measuring means changes the distance in the Z-axis direction between the distance measuring means and the object to be measured by the distance measuring means. The distance measuring means is provided with a calibration means for detecting calibration data indicating a mutual relationship from the distance data when measuring an arbitrary calibration point and the movement position data of the movement position detecting means in the Z-axis direction. Arranged symmetrically about the axis In addition to a plurality of light receiving systems having different light receiving angles as one set and a switching means for selecting the output from each set, the calibration means is a means for detecting the calibration data for each light receiving system. A three-dimensional shape measuring device characterized by performing control to calibrate the distance data when the main measurement is performed by the distance measuring means with the calibration data.