JPH07260471A - Measuring apparatus of surface shape - Google Patents

Abstract

PURPOSE:To measure the surface shape of an object, to be measured, with high accuracy by a method wherein information on the angle of inclination of a contact measuring point by a measuring probe is input and a measuring force is controlled in such a way that a contact deformation amount in the vertical direction is always definite. CONSTITUTION:While a measuring probe 1 is being moved to the X-direction, the movement of a probe shaft 3 is controlled by an X-Z coordinate-system drive means in such a way that the measuring probe comes into contact with the surface of an object 2 to be measured, and contact points of the measuring probe 1 by a coordinate measuring means are measured at prescribed intervals. A means which controls a measuring force is added to this constitution in such a way that a contact deformation amount due to the measuring probe 1 becomes always definite. That is to say, the control means reads out the angle of inclination theta of a measuring point from an input means on the basis of information on the angle of inclination of the surface of the object to be measured, and a measuring force P is controlled so as to satisfy an expression of P=P0sq. rt. COStheta (in the expression, P0 represents the measuring force at an angle of inclination of 0). Thereby, it is possible to obtain the measuring apparatus in which an error due to a change in the contact deformation amount is avoided and whose measuring accuracy can be enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a contact type coordinate measuring device.

[0002]

2. Description of the Related Art Conventionally, optical elements such as lenses and reflecting mirrors,
A contact-type coordinate measuring device as shown in FIG. 16 is used for measuring the surface shape of such a mold object for an optical element. This is widely used to measure the cross-sectional shape or surface shape of a three-dimensional object.
A tracing stylus 201 supported by an xyz-direction driving mechanism moves on the surface of the object to be measured 202 and detects the three-dimensional coordinates of a contact point to measure the surface shape of the object to be measured.

In such a coordinate measuring device, the measuring element 20
The measurement force on the surface of the DUT 202 is constant. For example, in the case of a structure in which the weight acting on the tracing stylus 201 is balanced by a weight (not shown), the weight of the weight is made slightly smaller than the weight of the tracing stylus to obtain a measuring force corresponding to the difference in weight. There is. Also,
In the case of a structure in which the gravity acting on the tracing stylus 201 is balanced by a spring force, a position where the amount of contraction of the spring is constant is detected, and the measuring force is kept constant by maintaining this position.

[0004]

However, when the measuring force on the surface to be measured of the probe is constant as in the above-mentioned conventional coordinate measuring apparatus, the contact between the probe and the object to be measured due to the contact of the probe. The sum of the deformation amounts (hereinafter, simply referred to as “contact deformation amount”) is not constant depending on the tilt angle of the surface of the measured object.

If the amount of contact deformation is not constant in this way, a measurement error occurs, and the object to be measured is an optical element such as a lens or a reflecting mirror, or a submicron such as a mold for such an optical element (plastic, glass mold, etc.). Alternatively, when a shape accuracy higher than that is required, there is a problem that it is not possible to meet a strict requirement for measurement accuracy.

In view of the above problems, the main object of the present invention is to obtain a surface profile measuring apparatus capable of measuring the surface profile of an object to be measured with high accuracy. Another object of the present invention is to obtain an apparatus capable of highly accurate surface shape measurement by keeping the amount of contact deformation in the direction perpendicular to the surface of the object to be measured always constant. Another object is to obtain an appropriate control condition for the measuring force of the probe so that the contact deformation amount in the direction perpendicular to the surface of the object to be measured is constant.

[0007]

In order to achieve the above object, in the surface profile measuring apparatus according to the first aspect of the present invention, the tracing stylus is moved on a curved surface having a change in inclination angle of the object to be measured. A surface profile measuring device for measuring the surface profile of an object to be measured by detecting the three-dimensional coordinates of a contact point, the input for inputting inclination angle information of a contact measuring point by the contact point of the surface of the object to be measured. Means for controlling the measuring force of the tracing stylus based on the tilt angle information obtained by the inputting means so that the contact deformation amount due to the contact between the tracing stylus and the tracing stylus becomes constant in the direction perpendicular to the surface to be measured. When the measuring force is P, the inclination angle is θ, and the measuring force when the inclination angle is 0 is P ₀ , the control means satisfies the following formula. . P = P ₀ / cos θ

[0008]

According to the present invention as set forth in claim 1, the control means controls the measuring force of the probe based on the inclination angle information of the contact measuring point by the probe on the surface of the object to be measured obtained by the input means. This is a device for measuring the surface shape of a measurement object.
Therefore, according to the present invention, by controlling the measuring force, the contact deformation amount in the vertical direction with respect to the surface of the object to be measured can always be made constant, and the measurement error caused by the variation of the contact deformation amount can be avoided. , The measurement accuracy is improved.

That is, the control means sets the measuring force to P,
When the inclination angle is θ and the measurement force when the inclination angle is 0 is P ₀ , the contact deformation amount is measured on the surface of the object to be measured by controlling the measurement force so as to satisfy P = P ₀ / COS θ. In contrast, it can be constant in the vertical direction.

FIG. 14 shows a conceptual diagram of the tracing stylus section. Control means for controlling the measuring force acting on the object to be measured b via the measuring element a is connected to the measuring element shaft c. At the position where the inclination angle of the surface of the object to be measured is θ, measure the measuring force a
When contacted with, the surface to be measured is deformed at the contact point by the contact deformation amount dn in the direction perpendicular to the surface to be measured. Actual deformation occurs in both the probe a and the object b to be measured, but here, for the sake of easy understanding, it is shown that the object b only deforms.

At this time, the force N perpendicular to the surface to be measured at the contact point is expressed by the following equation (11). N = Pcos θ Equation (11)

The contact deformation amount dn due to the force N is expressed by the following formula (12) according to the Hertz formula. dn = AN ^2/3 (where A is a constant) (12) The constant A is determined by the material and the radius of curvature of the probe a and the object b. The radius of curvature of the object b to be measured differs depending on the location, but since it is generally sufficiently larger than the radius of curvature of the probe a, the error can be ignored even if it is considered as a plane.

The contact deformation amount dn due to the probe a,
It is expressed by equation (3). dn = A (Pcos θ) ^2/3 (13) Equation

In order that the contact deformation amount due to the measuring force of the probe becomes constant in the direction perpendicular to the surface of the object to be measured,
Since equation (13) must be constant, the following equation (14) holds. P = B / cos θ (B is a constant) Equation (14)

In the equation (14), if the measuring force P = P ₀ when the inclination angle θ = 0, the equation (14) becomes the following equation (15), and the following is obtained between θ and P / P ₀ : Table 1 shows the relationship. P = P ₀ / cos θ (15) Equation

[0016]

[Table 1]

Therefore, if the measuring force of the probe is controlled according to the inclination angle θ of the object to be measured so that the relationship of Table 1, that is, the expression (15) is maintained, the contact in the direction perpendicular to the surface to be measured is achieved. Deformation amount dn
Is always constant.

In the present invention, it is necessary to input the tilt angle information of the measurement point from the input means, but a method of obtaining this tilt angle information will be described below. First, there is a method of obtaining the contact point, that is, the tilt angle information of the measurement point, from the design shape (expression, point sequence) of the object to be measured. This is effective when the actual shape of the object to be measured is close to the design shape with a small shape error. When using this method, it is necessary to know in advance the posture of the object to be measured with respect to the measurement coordinate system placed during measurement.

As another method, there is a method of obtaining from a rough shape measurement value measured by a conventional measuring method in which the measuring force is controlled to be constant in advance. This method does not require a small error between the actual shape of the object to be measured and the design shape, and considering that it is difficult to grasp and control the attitude with respect to the measurement coordinate system, the time required for the rough measurement is not sufficient. However, a value closer to the actual tilt angle can be obtained.

Further, as another method, there is a method of obtaining the tilt angle information in real time while measuring the shape. A tilt angle detecting probe can be used for this method.
That is, it is a method of directly obtaining the actual inclination angle of the contact point from the probe.

Specifically, a so-called surface normal detection probe can be used. In this probe, four electrodes, which are connected to the object to be measured by a constant-current power source via standard resistors, are symmetrically installed on the upper hemisphere on which a resistive thin film is formed on the spherical surface of the probe. When this probe is brought into contact with the object to be measured, a constant current circuit is formed, and the constant current flowing out from the constant current power supply is shunted in inverse proportion to the resistance value between the contact point and each electrode, and flows into each electrode. The position of the contact point on the probe can be detected by measuring the current flowing into the
Further, the unit normal vector of the contact point, that is, the inclination angle of the contact point can be detected from the contact point position and the probe center coordinate value. When using such a surface normal detection probe,
The device under test must be a conductor.

As a method of obtaining angle information in real time, there is a method of estimating the inclination angle of the measurement point from the immediately preceding measurement coordinate data. This method is possible if there are two or more already measured points, but as shown in FIG. 15A, when two-point data is used, the inclination angle is estimated from a straight line passing through the two points. Therefore, the angle error becomes large when performing the measurement of the curved surface of the DUT surface.

When using three-point data (see FIG. 15)
(B) Since an arc or a quadratic curve passing through three points can be obtained, the error of the estimated tilt angle with respect to the actual tilt angle is small. When obtaining the tilt angle information in real time using the immediately preceding data, N of 3 points, preferably 4 points or more
The estimated angle information may be obtained by obtaining a (N-1) th degree curve passing through the points. Such an error of the estimated tilt angle has a relatively small sensitivity to the contact deformation amount, and its influence on the actual surface shape measurement is negligible. However, it should be noted that if the order is too high, a smooth curve may not be obtained. Further, N pieces of measurement data at the measurement start end are not used for final shape data.

With such a method for obtaining the tilt angle information in real time, an extra time for measuring the rough shape in advance is unnecessary. In particular, the method using the already-measured point data does not require a special probe such as a surface normal detection probe, and has a simple structure without the restriction that the object to be measured must be a conductor. Of course, the method of obtaining the tilt angle information usable in the present invention is not limited to the method described above.

Further, in the present invention, the measuring force of the tracing stylus is controlled by the control means, and the concrete means will be described below. First, there is a method of controlling the spring force. That is, the probe shaft holding the probe is supported by the drive mechanism (Z-axis) of the device body by a spring, and the weight of the probe and the probe shaft (hereinafter referred to as the probe portion) and the spring force are balanced to make the surface of the object to be measured. The contact point is brought into contact with the surface of the object to be measured in a state where the lower end of the contact point is lifted to a certain extent and the spring is contracted compared to the state in which the contact point (the measuring force is zero). At this time, a measuring force is generated which is determined by the amount of contraction of the spring and the spring constant.

Therefore, the measuring force can be controlled by controlling the amount of contraction of the spring by, for example, the Z-axis servomotor. Incidentally, in the case of such a control means utilizing the spring force, a mechanism for detecting the amount of contraction of the spring or the amount of displacement of the probe or the probe shaft with respect to the Z stage and feeding back the detection result is required.

Further, as another control means, there is a means for controlling the thrust of the voice coil motor. Since the voice coil motor generates a thrust force proportional to the magnitude of the input current, the current value is lower than the state where the probe weight is balanced by the thrust force of the voice coil motor (measuring force is zero). The probe is brought into contact with the surface of the object to be measured with. At this time, a measuring force is generated, but the measuring force can be controlled by controlling the input current value. If the input current is constant, the measuring force is constant, and the measuring force is constant even if the relative displacement amount of the probe / probe shaft with respect to the Z stage changes.

Further, the control by a pneumatic cylinder may be used. Since the pneumatic cylinder generates a thrust force proportional to the magnitude of the input air pressure, the probe pressure is lower than when the probe weight is balanced by the thrust of the pneumatic cylinder (measurement force is zero). To the surface of the object to be measured. At this time, a measuring force is generated, but the measuring force can be controlled by controlling the input air pressure. If the input air pressure is constant, the measuring force is constant, and the measuring force is constant even if the relative displacement amount of the probe / probe shaft with respect to the Z stage changes.

Further, the control of the measuring force can be performed with a higher resolution if the mechanism provided separately from the control method by the control means cancels the self-weight of the probe section. For example, by controlling the spring, the voice coil motor, or the pneumatic cylinder as the control means while balancing the weight of the probe with the weight, the voice coil motor, the pneumatic cylinder, or the like, Control the measuring force. The method used as the control means in the present invention is not limited to the one described above.

[0030]

EXAMPLES The present invention will be described below with reference to examples. First, FIG. 1 shows an outline of a measuring system configuration of a surface profile measuring apparatus according to the present invention. In this device, it is necessary to move the probe in the X-axis direction while touching the surface of the object to be measured.
The movement of the probe axis in the X and Z coordinate systems is controlled by the Z coordinate system driving means, and the contact points (measurement points) of the probe are measured by the coordinate measuring means at predetermined intervals in the X coordinate system. The measurement in the X-Z coordinate system is performed according to the movement of the measured object in the Y-axis direction by the driving of the Y-coordinate system driving means.
By performing the measurement at predetermined intervals in the coordinate system, the three-dimensional coordinates of the contact point of the probe are measured, and the three-dimensional shape of the surface of the object to be measured is obtained. The above configuration is the same as that of the conventional coordinate measuring device.

The apparatus of the present invention further comprises a control means for controlling the measuring force of the probe on the surface of the object to be measured. That is, the control means always maintains a constant contact deformation amount in the vertical direction with respect to the measured surface at the measurement point where the contact point is in contact, based on the inclination angle information of the measured object surface obtained from the input means. As described above, the measuring force of the tracing stylus is controlled according to the inclination angle of the measuring point. In order to keep the contact deformation amount (FIG. 14dn) in the direction perpendicular to the surface to be measured always constant, it is sufficient to perform control so as to satisfy the above formula (15).

As for the inclination angle information of the surface of the object to be measured sent from the input means to the control means, when the actual shape of the object to be measured is close to the design shape, the angle information based on the design value is input as the external information. You can enter it in. Further, the rough surface shape of the object to be measured, which has been measured using the conventional method, may be input in advance as the angle information. Further, the estimated tilt angle of the measurement point may be obtained from the data of the already measured point and stored as internal information in the input means.

(Embodiment 1) As a first embodiment of the present invention,
A case of a surface shape measuring device using a spring force as a control means will be described. Here, the measuring force of the probe 1 is controlled by controlling the amount of contraction of the spring, but the amount of contraction of the spring that determines the measuring force, that is, the self-weight of the spring and the probe portion is balanced and the measuring force of the probe is A differential transformer is used in the detection system for detecting the axial displacement L of the probe portion from the state of 0.

FIG. 2A is a schematic diagram of the probe section of the surface profile measuring apparatus of this embodiment. The probe shaft 2 holding the probe 1 is supported by the spring 3 on the Z axis. A core 5 is attached to the probe shaft 2 and detects a change in the voltage generated in the coil 4 of the differential transformer as the probe shaft 2 moves in accordance with the displacement in the Z-axis direction.

In the above structure, when the surface shape measurement of the object to be measured is started, the object to be measured from the input means corresponds to the position of the measuring point of the tracing stylus 1 which is determined by the driving of the XYZ coordinate system. Inclination angle θ of the measurement point based on the angle information of the object
Is read out, and a predetermined measuring force that should satisfy the equation (15) is determined from the tilt angle θ.

On the other hand, the control means obtains the actual measurement force value at the measurement point of the probe 1 determined from the displacement amount of the spring 3 in the detection system (here, the differential transformer), and the detection result is obtained. The servo motor (not shown) of the Z-axis coordinate system is driven and controlled so as to be fed back and the predetermined measuring force that should satisfy the above formula (15) is determined, and the three-dimensional coordinates of the measuring point under the predetermined measuring force are determined. To do.

The above operation is performed by X and Y on the surface of the object to be measured.
For the measurement points at predetermined intervals in the coordinate system, the contact deformation amount in the direction perpendicular to the measured surface at the measurement point of the probe 1 is always constant under the predetermined measurement force that satisfies the formula (15). By determining the Z coordinate system position and performing three-dimensional coordinate detection, the three-dimensional shape of the surface of the object to be measured can be measured with high accuracy.

In the surface profile measuring apparatus of this embodiment, the measuring element 1 is a spherical ruby having a diameter of 2 mm, the object to be measured is optical glass, and the object to be measured is controlled with the measuring force of the measuring element 1 with an accuracy of 0.1 gf. As a result of measuring the surface shape of the optical glass, the inclination angle θ = 0 °, that is, the contact deformation amount in the case where the tracing stylus 1 is in vertical contact with the surface to be measured and the inclination angle θ = 4.
Approximately 0.0 with the amount of contact deformation when contacting a 5 ° position
The difference was 01 μm. This has a measuring force of 5g as before.
θ = 0 ° and θ = 45 when measurement is performed with constant f
The difference between the contact deformation amount and the contact deformation amount is about 0.01 μm, which is very small. It is apparent that the measurement accuracy is greatly improved in the apparatus according to the present embodiment because the measurement error due to the change in the contact deformation amount is almost eliminated. Is.

In this embodiment, a spherical ruby is used for the measuring element, but various measuring elements such as ceramics, diamond, steel ball can be used.

Further, in the present apparatus, a guide 6 for guiding the movement of the probe shaft in the Z-axis direction due to the control of the measuring force.
Is provided. As the guide method, a hydrostatic bearing can be used as shown in FIG. Hydrostatic bearings have very low frictional resistance, are advantageous in reducing measurement force, and have high precision in motion performance. Also, a relatively long stroke width can be obtained.

As another probe axis guide system, there is a system using a parallel spring 8 as shown in FIG. 2 (b). This is a highly accurate method for minute changes.
However, since the spring force changes due to displacement, there is a limit to the range in which displacement is possible.

Also, the case where a differential transformer is used as a method for detecting the amount of contraction of the spring and the amount of axial displacement L of the probe portion has been described, but there are various other methods for detecting the amount of displacement L. However, in both cases, it is necessary to use a non-contact detection system so as not to affect the measuring force of the probe. Another example of such a non-contact detection method is shown below.

For example, there is a method using a laser length measuring machine shown in FIG. This is because the beam emitted from the laser light source 11 is divided into two beams in the interference optical system 12, one of which is reflected on the probe shaft upper surface S and the other of which is reflected by the fixed reflecting mirror of the interference optical system 12, and these are appropriately selected. The optical paths of the two reflected lights having the optical path difference (phase difference) are combined again to cause interference, and the light receiving unit 13
To obtain an interference image. Since this interference image changes according to the position change of the probe shaft upper surface S, the displacement amount L of the probe portion can be obtained by detecting this. According to this method, the displacement amount can be detected with high resolution and high accuracy, but the dynamic range is large and it is excessive for measuring a minute displacement.

Next, a detection system using an optical displacement meter will be shown. In FIG. 4, a laser displacement meter and an LED displacement meter 14 are provided,
Light is projected onto the probe shaft upper surface S, and the probe shaft upper surface S
The displacement amount L is obtained by detecting a change in the reflection position of light accompanying the movement of the. With this method, it is possible to set at various levels from relatively low resolution to high resolution, and the dynamic range is medium.

An optical fiber type displacement gauge as shown in FIG. 5 can also be used. (Optical fiber) The displacement amount L is obtained by projecting the light from the light source / detection unit 16 from the tip of the optical fiber 15 onto the probe shaft upper surface S and detecting the change in the reflected light amount from this. Although this method has a narrow dynamic range, it is suitable for measuring small displacements with high resolution.

Further, FIG. 6 shows a detection system using the capacitance type displacement meter 18. This is because the sensor unit 17 measures the capacitance between the sensor and the probe shaft upper surface S, which is the measurement target, and detects the change to measure the displacement L.
Is to seek. Although this capacitance type displacement meter has a narrow dynamic range, it is suitable for measuring minute displacement with high resolution.

There is also a detection system using a linear scale as shown in FIG. This is because the displacement caused by the movement of the probe shaft of the scale attached to the probe shaft 2 is detected by the optical or magnetic detector 20.
Can be asked. This linear scale detection method can be set at various levels from low resolution to high resolution, has various dynamic ranges, and suitable specifications can be selected from minute displacement to long stroke.

Further, the ultrasonic type displacement meter 2 as shown in FIG.
There is also a method of detecting the displacement amount L by 1. In this, the amount of displacement L can be obtained from the time required to project the ultrasonic wave on the upper surface S of the probe shaft, to reflect and return the ultrasonic wave, and to change the time with the movement of the probe shaft.

(Embodiment 2) Next, as a second embodiment of the present invention, a case of a surface profile measuring apparatus using thrust of a voice coil motor as a control means will be described. FIG. 9 is a schematic configuration diagram of the probe unit of the surface profile measuring apparatus of this embodiment. The probe shaft 102 holding the probe 101 is
The core 104 provided on the probe shaft 102 is magnetically attracted to the voice coil 103 fixed to the Z-axis, so that the core 104 is supported by the Z-axis which moves in the Z coordinate system.

Such thrust is proportional to the magnitude of the input current. Here, the relative displacement of the probe shaft 102 with respect to the Z axis is smoothly guided in the axial direction by the probe guide 105 including the static gas bearing 106. The measuring force is zero when the weight of the probe section is balanced by the thrust of the voice coil motor.The measuring force is generated by lowering the current value from this state, and the measuring force is generated by controlling the input current value. Can be controlled.

When the surface shape measurement of the object to be measured is started in the above structure, the object to be measured from the input means corresponds to the position of the measuring point of the tracing stylus 101, which is determined by driving the XYZ coordinate system. The inclination angle θ of the measurement point is read based on the angle information of the object, and the predetermined measurement force that should satisfy the above equation (15) is determined from this inclination angle θ.

On the other hand, the control means controls the input current value to the voice coil motor so as to obtain a predetermined measuring force that should satisfy the expression (15), and the three-dimensional coordinates of the measuring point under the predetermined measuring force. To decide. In the voice coil motor, if the input current value is constant, the measuring force is constant even if the relative displacement amount L of the probe unit with respect to the Z coordinate system changes. Therefore, the measurement force can be controlled directly by controlling the input current value, so that the measurement force is detected from the displacement L and the detection result is fed back to aim at the target measurement force, as in the case of the control of the spring force. No detection system is required.

The above operation is performed by X and Y on the surface of the object to be measured.
With respect to the measurement points at predetermined intervals in the direction, under the predetermined measurement force that always satisfies the expression (15), that is, by performing the three-dimensional coordinate detection in the state where the contact deformation amount in the axial direction of the probe 101 is always constant, The three-dimensional shape of the surface of the object to be measured can be measured with high accuracy.

(Embodiment 3) Next, as a third embodiment,
A case of a surface shape measuring device using air pressure as the control means will be described. FIG. 10 is a schematic configuration diagram of the probe unit of the surface profile measuring apparatus of this embodiment. The probe shaft 112 holding the tracing stylus 111 is supported on the Z axis by the piston 114 provided on the probe shaft 112 being sucked in the cylinder 113 fixed to the Z axis.

The thrust produced by such a pneumatic cylinder is
It is proportional to the magnitude of the input air pressure. Here, the relative displacement of the probe shaft 112 with respect to the Z axis due to the reciprocating motion of the piston 114 in the cylinder 113 according to the magnitude of the air pressure is smoothly performed in the axial direction by the probe guide 115 including the gas static pressure bearing 116. Be guided. The measuring force is zero when the weight of the probe portion is balanced by the thrust of the pneumatic cylinder. The measuring force is generated by lowering the air pressure from this state, and the measuring force can be controlled by controlling the air pressure.

In the above-described structure, when the surface shape measurement of the object to be measured is started, the object to be measured from the input means corresponds to the position of the measuring point of the tracing stylus 111, which is determined by driving the XYZ coordinate system. The inclination angle θ of the measurement point is read based on the angle information of the object, and the predetermined measurement force that should satisfy the above equation (15) is determined from this inclination angle θ.

On the other hand, the control means controls the input current value to the voice coil motor so as to obtain a predetermined measuring force that should satisfy the expression (15), and the three-dimensional coordinates of the measuring point under the predetermined measuring force. To decide. In the pneumatic cylinder, if the input air pressure is constant, the measuring force is constant even if the relative displacement amount L of the probe unit with respect to the Z coordinate system changes. Therefore, the control of the measuring force can be performed by directly controlling the input air pressure. Therefore, as in the case of controlling the spring force, the measuring force is detected from the displacement amount L and the detection result is fed back to aim at the target measuring force. No detection system is required.

The above operation is performed for X and Y on the surface of the object to be measured.
The measurement points at predetermined intervals in the direction are always under a predetermined measurement force that satisfies the expression (15), that is, in the state where the contact deformation amount in the direction perpendicular to the measured surface at the measurement points of the probe 111 is always constant. By performing the three-dimensional coordinate detection, the three-dimensional shape of the surface of the object to be measured can be measured with high accuracy.

(Embodiment 4) In the embodiment described above,
The control means is configured to cancel the self-weight of the probe part to some extent and further control the measuring force by the same means, but a means for canceling the self-weight of the probe part is provided separately from the means for controlling the measuring force. It may be configured.
Therefore, first, as a fourth embodiment of the present invention, a case where a weight is used as a means for canceling the weight of the probe portion to some extent will be described below.

FIG. 11 (a) shows an outline of the probe part of the surface profile measuring apparatus constructed such that the measuring force is controlled by controlling the spring force after the weight of the probe part is balanced to some extent by the weight. It is a thing. The probe shaft 122 holding the probe 121 is a pulley 1 fixed to the Z-axis.
It is supported in balance with the weight 123 via 24. Here, the relative displacement of the probe shaft 122 with respect to the Z axis is smoothly guided in the axial direction by the probe guide 125 including the static gas bearing 126.

The probe shaft 122 is also supported on the Z axis by the spring 127, and when the surface shape measurement of the object to be measured is started and the probe 121 comes into contact with the surface of the object to be measured, the spring 127 is It is in a state of being contracted to the extent that a measuring force is generated at the contact point. The amount of contraction of the spring is controlled by driving a servo motor (not shown) in the Z-axis coordinate system to determine the three-dimensional coordinates of the measurement point under a predetermined measurement force. When the measuring force is controlled by controlling the spring force, it is necessary to provide a detection system that detects the amount of contraction (displacement amount L) of the spring. 2 to 8 in the first embodiment, a variable transformer, a laser displacement meter, an optical fiber type displacement meter, a capacitance type displacement meter, a linear scale ultrasonic displacement meter, or the like. You can select and use it.

In the above-mentioned structure, when the surface shape measurement of the object to be measured is started, the object to be measured from the input means corresponds to the position of the measuring point of the tracing stylus 121 determined by the driving of the XYZ coordinate system. The inclination angle θ of the measurement point is read based on the angle information of the object, and the predetermined measurement force that should satisfy the above equation (15) is determined from this inclination angle θ.

On the other hand, the control means obtains the actual measuring force value at the measuring point of the tracing stylus 121, which is determined from the displacement L of the spring 127 in the detection system, and feeds back the detection result, and the above (15) A Z-axis coordinate system servomotor (not shown) is drive-controlled so as to obtain a predetermined measurement force that should satisfy the expression, and the three-dimensional coordinates of the measurement point under the predetermined measurement force are determined.

The above operation is performed by X and Y on the surface of the object to be measured.
For the measurement points at predetermined intervals in the coordinate system, the Z coordinate system position is always determined under the predetermined measurement force that satisfies the formula (15), that is, the contact deformation amount of the probe 121 in the axial direction is always constant. By detecting the coordinates, the three-dimensional shape of the surface of the object to be measured can be measured with high accuracy. In the surface profile measuring apparatus having such a configuration, the means for canceling the self-weight of the probe unit is provided separately from the spring force control mechanism for controlling the measuring force, so that the spring as shown in the first embodiment is provided. The measurement force can be controlled with higher resolution than the configuration using only the force.

Further, a configuration using another method for controlling the measuring force may be adopted. For example, as shown in FIG.
The second embodiment has a configuration in which the probe portion is supported with the weight 123 being canceled to some extent by the weight 123 via the pulley 124.
It is equipped with the voice coil motor used in. The core 129 provided on the probe shaft 122 is magnetically attracted by the thrust generated according to the current value input to the voice coil 128 fixed to the Z axis.

Therefore, the thrust force is controlled by controlling the input current value, and the thrust force is always controlled in the probe axis direction while being controlled so as to obtain a predetermined measuring force satisfying the expression (15) according to the tilt angle information from the input means. The three-dimensional shape of the surface of the object to be measured is measured while the amount of contact deformation is constant. Here, it is not necessary to provide a detection system for detecting the amount of displacement as in the case of controlling the measuring force by the spring force. In the surface shape apparatus using this voice coil motor, only the voice coil motor shown in the second embodiment is provided by providing the means for canceling the weight of the probe section separately from the means for controlling the measuring force. The measurement force can be controlled with higher resolution than the configuration used.

Further, FIG. 11C shows a structure provided with the pneumatic cylinder used in the third embodiment for controlling the measuring force. As in FIGS. 11 (a) and 11 (b), the probe portion is a pulley 12
The piston 131 provided on the probe shaft 122 can be reciprocated by the thrust generated according to the magnitude of the air pressure input in the cylinder 130 while being supported by the weight 123 via the weight 123 to some extent. Have been sucked into.

Therefore, the thrust in the cylinder 130 is controlled by controlling the air pressure, and the measured surface is constantly controlled according to the tilt angle information from the input means so that the predetermined measuring force satisfies the expression (15). The three-dimensional shape of the surface of the object to be measured is measured with a constant contact deformation amount in the vertical direction. Here, it is not necessary to provide a detection system for detecting the displacement amount as in the case of controlling the measuring force by the spring force. In the surface profile measuring apparatus using this pneumatic cylinder, only the pneumatic cylinder shown in the third embodiment is used because the means for canceling the self-weight of the probe part is provided separately from the means for controlling the measuring force. The measurement force can be controlled with higher resolution than the conventional configuration.

(Embodiment 5) Next, as a fifth embodiment, a case where a voice coil motor is used as a means for canceling the weight of the probe portion to some extent will be described below. 12
(A) shows an outline of the probe part of the surface profile measuring apparatus configured to control the measuring force by controlling the spring force after balancing the self-weight of the probe part to some extent with a voice coil motor. . The probe shaft 142 holding the tracing stylus 141 is a voice coil 143 in which a core 144 provided on the probe shaft 142 is fixed to the Z axis.
The probe is supported by the Z-axis that moves in the coordinate system in a state where the weight of the probe is canceled to some extent by being magnetically attracted to the Z-axis. Here, the relative displacement of the probe shaft 142 with respect to the Z axis is smoothly guided in the axial direction by the probe guide 145 including the static gas bearing 146.

The probe shaft 142 is also supported on the Z-axis by the spring 147, and when the surface shape measurement of the object to be measured is started and the probe 141 comes into contact with the surface of the object to be measured, the spring 147 is It is in a state of being contracted to the extent that a measuring force is generated at the contact point. The amount of contraction of the spring is controlled by driving a servo motor (not shown) in the Z-axis coordinate system to determine the three-dimensional coordinates of the measurement point under a predetermined measurement force. When the measuring force is controlled by controlling the spring force, it is necessary to provide a detection system that detects the amount of contraction (displacement amount L) of the spring. This is based on the method such as the variable transformer, the laser displacement meter, the optical fiber displacement meter, the capacitance displacement meter, the linear scale, and the ultrasonic displacement meter as shown in FIGS. 2 to 8 in the first embodiment. It may be appropriately selected and used.

In the above structure, when the surface shape measurement of the object to be measured is started, the object to be measured from the input means corresponds to the position of the measuring point of the tracing stylus 141 which is determined by the driving of the XYZ coordinate system. The inclination angle θ of the measurement point is read based on the angle information of the object, and the predetermined measurement force that should satisfy the above equation (15) is determined from this inclination angle θ.

On the other hand, the control means obtains the actual measurement force value at the measurement point of the tracing stylus 121, which is determined from the displacement L of the spring 127 in the detection system, and feeds back the detection result. A Z-axis coordinate system servomotor (not shown) is drive-controlled so as to obtain a predetermined measurement force that should satisfy the expression, and the three-dimensional coordinates of the measurement point under the predetermined measurement force are determined.

The above operation is performed by X and Y on the surface of the object to be measured.
The Z coordinate system in which the contact deformation amount in the direction perpendicular to the surface to be measured of the tracing stylus 141 is always constant under a predetermined measuring force that satisfies the formula (15) at measurement points at predetermined intervals in the coordinate system. By determining the position and detecting the three-dimensional coordinates, the three-dimensional shape of the surface of the object to be measured can be measured with high accuracy. In the surface profile measuring apparatus having such a configuration, the means for canceling the self-weight of the probe unit is provided separately from the spring force control mechanism for controlling the measuring force, so that as shown in the first embodiment. The measurement force can be controlled with higher resolution than the configuration using only the spring.

Further, in the fifth embodiment, as a constitution using another method for controlling the measuring force, for example, FIG.
As shown in (1), the weight of the probe portion is balanced to some extent by the first voice coil motor, and then the second voice coil motor is provided for controlling the measuring force. The probe shaft 142 holding the tracing stylus 141 magnetically attracts the core 144 of the first voice coil motor provided on the probe shaft 142 to the voice coil 143 fixed to the Z-axis, so that the weight of the probe portion is reduced. Are supported by the Z axis that moves in the coordinate system while being canceled to some extent. Further, the core 149 of the second voice coil motor provided on the probe shaft 142 is magnetically attracted by the thrust generated according to the current value input to the voice coil 148 fixed to the Z axis.

Therefore, the thrust is controlled by controlling the input current value to the second voice coil motor,
According to the inclination angle information from the input means, the contact deformation amount in the direction perpendicular to the surface to be measured is constantly controlled while being controlled so as to obtain a predetermined measuring force that satisfies the expression (15). The three-dimensional shape is measured. Here, there is no need to provide a detection system for detecting the amount of displacement as in the case of measuring force control by spring force. In the surface shape apparatus using the two voice coil motors, the voice coil motor for canceling the weight of the probe unit and the voice coil motor for controlling the measuring force are separately provided, and thus the surface shape apparatus is shown in the second embodiment. As described above, the measurement force can be controlled with higher resolution than the configuration using only one voice coil motor.

Further, FIG. 12C shows a structure provided with the pneumatic cylinder used in the third embodiment for controlling the measuring force. As in FIGS. 12A and 12B, the probe portion is supported by the Z-axis with its own weight being canceled to some extent by the voice coil motor, and the piston 151 provided on the probe shaft 142 is input in the cylinder 150. It is sucked so as to be able to reciprocate by the thrust generated according to the magnitude of the air pressure.

Therefore, the thrust in the cylinder 150 is controlled by controlling the air pressure, and the surface to be measured is constantly controlled while the predetermined measurement force satisfying the expression (15) is obtained according to the inclination angle information from the input means. The three-dimensional shape of the surface of the object to be measured is measured with a constant contact deformation amount in the vertical direction. Here, it is not necessary to provide a detection system for detecting the displacement amount as in the case of controlling the measuring force by the spring force. In the surface profile measuring apparatus using this pneumatic cylinder, by providing the means for canceling the self-weight of the probe part separately from the means for controlling the measuring force,
The measurement force can be controlled with higher resolution than the configuration using only the pneumatic cylinder shown in the third embodiment.

(Sixth Embodiment) Next, a sixth embodiment of the present invention will be described below in which an air cylinder is used as a means for canceling the weight of the probe portion to some extent. FIG.
(A) shows an outline of the probe part of the surface profile measuring apparatus configured to control the measuring force by controlling the spring force after balancing the own weight of the probe part to some extent with an air cylinder. The probe shaft 162 holding the tracing stylus 161 is sucked by the thrust generated according to the magnitude of the air pressure input in the cylinder 163 in which the piston 164 provided on the probe shaft 162 is fixed to the Z axis. Is supported by the Z-axis that moves in the coordinate system while the weight of the probe portion is canceled to some extent. Here, the relative displacement of the probe shaft 162 with respect to the Z axis is determined by the probe guide 165 including the static gas bearing 166.
Guided smoothly in the axial direction.

The probe shaft 162 is also supported on the Z-axis by the spring 167, and when the surface shape measurement of the measured object is started and the contact point 161 contacts the surface of the measured object, the spring 167 moves. It is in a state of being contracted to the extent that a measuring force is generated at the contact point. The amount of contraction of the spring is controlled by driving a servo motor (not shown) in the Z-axis coordinate system to determine the three-dimensional coordinates of the measurement point under a predetermined measurement force. When the measuring force is controlled by controlling the spring force, it is necessary to provide a detection system that detects the amount of contraction (displacement amount L) of the spring. For this, the detection method shown in FIGS. 2 to 8 in the first embodiment may be appropriately selected and used.

In the above structure, when the surface shape measurement of the object to be measured is started, the object to be measured from the input means corresponds to the position of the measuring point of the tracing stylus 161 determined by the driving of the XYZ coordinate system. The inclination angle θ of the measurement point is read based on the angle information of the object, and the predetermined measurement force that should satisfy the above equation (15) is determined from this inclination angle θ.

On the other hand, the control means obtains the actual measuring force value at the measuring point of the tracing stylus 161 determined from the displacement amount L of the spring 167 in the detection system, and feeds back the detection result, and (15) A Z-axis coordinate system servomotor (not shown) is drive-controlled so as to obtain a predetermined measurement force that should satisfy the expression, and the three-dimensional coordinates of the measurement point under the predetermined measurement force are determined.

The above operation is performed by X and Y on the surface of the object to be measured.
For the measurement points at predetermined intervals in the coordinate system, always determine the Z coordinate system position where the contact deformation amount in the direction perpendicular to the surface to be measured is always constant under the predetermined measurement force that satisfies the formula (15). By performing the three-dimensional coordinate detection, the three-dimensional shape of the surface of the object to be measured can be measured with high accuracy. In the surface profile measuring apparatus having such a configuration, the means for canceling the self-weight of the probe unit is provided separately from the spring force control mechanism for controlling the measuring force, so that the spring as shown in the first embodiment is provided. The measurement force can be controlled with a higher resolution than the configuration using only.

In addition, as a configuration in which another method is used for controlling the measuring force in the sixth embodiment, for example, FIG.
As shown in FIG. 5, the weight of the probe portion is balanced to some extent by a pneumatic cylinder, and the voice coil motor used in the second embodiment is provided. The probe shaft 162 holding the tracing stylus 161 is a cylinder 163 in which a piston 164 provided on the probe shaft 162 is fixed to the Z axis.
The probe is supported by the Z-axis in a state where its own weight is canceled to some extent by being sucked by a thrust generated according to the magnitude of the air pressure input therein. Further, the core 169 provided on the probe shaft 162 is magnetically attracted by the thrust generated according to the current value input to the voice coil 168 fixed to the Z axis.

Therefore, the thrust is controlled by controlling the input current value to the voice coil motor, and the thrust is controlled so as to be the predetermined measuring force satisfying the expression (15) according to the tilt angle information from the input means. The three-dimensional shape of the surface of the object to be measured is always measured with the amount of contact deformation in the direction perpendicular to the surface to be measured being constant. Here, there is no need to provide a detection system for detecting the amount of displacement as in the case of measuring force control by spring force. In the surface shaping apparatus using this voice coil motor, the means for canceling the weight of the probe section and the means for controlling the measuring force are separately provided, so that the voice coil motor as shown in the second embodiment is provided. The measurement force can be controlled with a higher resolution than the configuration using only.

Further, FIG. 12C shows a probe equipped with a second pneumatic cylinder for controlling the measuring force after balancing the self-weight of the probe portion to some extent with the first pneumatic cylinder. Probe shaft 16 holding a probe 161
2 is the first piston 1 provided on the probe shaft 162.
64 is supported by the Z-axis with its own weight being canceled to some extent by being sucked by the thrust generated according to the magnitude of the air pressure input into the first pneumatic cylinder 163 fixed to the Z-axis. ing. Further, the second piston 171 provided on the probe shaft 162 is reciprocally sucked by the thrust generated according to the air pressure input into the second pneumatic cylinder 170 fixed to the Z axis.

Therefore, the thrust in the cylinder 170 is controlled by controlling the air pressure of the second pneumatic cylinder so that the predetermined measuring force satisfying the expression (15) is obtained according to the tilt angle information from the input means. The three-dimensional shape of the surface of the object to be measured is always measured while the contact deformation amount in the direction perpendicular to the surface to be measured is constant. Here, it is not necessary to provide a detection system for detecting the displacement amount as in the case of controlling the measuring force by the spring force. In the surface profile measuring apparatus using the two pneumatic cylinders, the pneumatic cylinder for canceling the self-weight of the probe portion and the pneumatic cylinder for controlling the measuring force are separately provided. The measurement force can be controlled with higher resolution than the configuration using only one pneumatic cylinder.

In the above embodiments, the hydrostatic bearing is used as the guide system for the probe shaft.
The hydrostatic bearing is not limited to the one using gas. Of course, not only the hydrostatic bearing but also a guide system that can smoothly guide the probe shaft in its axial direction (Z-axis direction) can be widely used. Since there is a method effective in some cases, it may be appropriately selected depending on the measurement conditions such as the shape of the object to be measured.

Further, regarding the method of obtaining the tilt angle information from the material of the measuring element, the measuring force control means, and the displacement amount detecting system necessary when the spring force is used for the measuring force control, including the above guide method, Although various things have been shown in the above embodiments, in forming the surface profile measuring device of the present invention, any combination can be arbitrarily selected, and the labor and cost at the time of assembling the device, the required measuring force In view of conditions such as control resolution and the degree of change in the surface shape of the object to be measured, a device having an appropriate level can be appropriately configured.

[0089]

As described above, according to the surface profile measuring apparatus of the present invention, it is possible to control the measuring force of the probe when measuring the surface profile. Therefore, by controlling this measuring force, the measurement can be performed with the amount of contact deformation on the surface of the object to be measured constantly kept constant, so that the measurement error caused by the variation in the amount of contact deformation can be eliminated, and the measurement accuracy of the surface shape can be improved. Has improved. In particular, by controlling the measuring force so as to satisfy the expression (15), the contact deformation amount in the direction perpendicular to the surface to be measured can be made constant.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a configuration of a measuring system using a surface profile measuring apparatus of the present invention.

FIG. 2 is a schematic configuration diagram of a probe unit of the surface profile measuring apparatus according to the first embodiment of the present invention, FIG. 2 (a) is a configuration in the case where a hydrostatic bearing is used for a probe shaft guide system, and FIG.
Shows a parallel spring as a guide system for the probe shaft.

FIG. 3 is a schematic configuration diagram of a probe unit when a laser length measuring machine is used for a displacement amount detection system as a modification of the surface profile measuring apparatus according to the first embodiment.

FIG. 4 is a schematic configuration diagram of a probe unit when a laser displacement meter is used in a displacement amount detection system as a modification of the surface profile measuring apparatus according to the first embodiment.

FIG. 5 is a schematic configuration diagram of a probe unit when an optical fiber displacement meter is used in a displacement amount detection system as a modification of the surface profile measuring apparatus according to the first embodiment.

FIG. 6 is a schematic configuration diagram of a probe unit when a capacitance type displacement meter is used in a displacement amount detection system as a modification of the surface profile measuring apparatus according to the first embodiment.

FIG. 7 is a schematic configuration diagram of a probe unit when a linear scale is used in a displacement amount detection system as a modification of the surface profile measuring apparatus according to the first embodiment.

FIG. 8 is a schematic configuration diagram of a probe unit when an ultrasonic displacement meter is used in a displacement amount detection system as a modification of the surface profile measuring apparatus according to the first embodiment.

FIG. 9 is a schematic configuration diagram of a probe unit of a surface profile measuring apparatus according to a second embodiment of the present invention.

FIG. 10 is a schematic configuration diagram of a probe unit of a surface profile measuring apparatus according to a third embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a probe unit of a surface profile measuring apparatus according to a fourth embodiment of the present invention, where (a) is a case where a spring force is used to control the measuring force, and (b) is a controlling the measuring force. When a voice coil motor is used for (1), (c) shows a case where a pneumatic cylinder is used for controlling the measuring force.

FIG. 12 is a schematic configuration diagram of a probe unit of a surface profile measuring apparatus according to a fifth embodiment of the present invention, in which (a) uses a spring force to control the measuring force, and (b) shows control of the measuring force. When a voice coil motor is used for (1), (c) shows a case where a pneumatic cylinder is used for controlling the measuring force.

FIG. 13 is a schematic configuration diagram of a probe unit of a surface profile measuring apparatus according to a sixth embodiment of the present invention, where (a) is a case where a spring force is used to control the measuring force, and (b) is a control of the measuring force. When a voice coil motor is used for (1), (c) shows a case where a pneumatic cylinder is used for controlling the measuring force.

FIG. 14 is an explanatory diagram for explaining the operation of the present invention.

15A and 15B are explanatory diagrams showing a method for obtaining tilt angle information in real time, where FIG. 15A illustrates a 2-point method and FIG. 15B illustrates a 3-point method.

FIG. 16 is a schematic configuration diagram of a conventional coordinate measuring device.

[Explanation of reference symbols] 1,101,111,121,141,161: Measuring element: Object to be measured S: Probe shaft upper surface 2, 102, 112, 122, 142, 162: Probe shaft 6, 105, 115, 125, 145, 165: probe guide 7, 106, 116, 126, 146, 166: hydrostatic bearing 8: parallel spring 3, 127, 147, 167: spring 4: coil (differential transformer) 5: core ( Differential transformer) 11: Laser light source 12: Interference optical system 13: Light receiving part 14: Laser displacement meter, LED type displacement meter 15: Optical fiber 16: Optical fiber light source / detection part 17: Capacitance sensor part 18: Static Capacitance detection unit 19: Scale 20: Linear scale detection unit 21: Ultrasonic displacement meter 103, 128, 143, 148, 168: Voice coil 104, 129, 144 149,169: Core (voice coil motor) 113,130,150,163,170 :( pneumatic)
Cylinder 114,131,151,164,171: Piston (pneumatic cylinder) 123: Weight 124: Pulley

Claims (1)

[Claims] 1. A surface shape measuring apparatus for measuring a surface shape of a measured object by moving a tracing stylus on a curved surface of a measured object having a change in inclination angle to detect three-dimensional coordinates of a contact point. And a sum of contact deformation amounts of the measuring element and the DUT due to contact of the measuring element, and an input unit for inputting inclination angle information of a contact measuring point by the measuring element on the surface of the measuring object. So as to be constant in the direction perpendicular to the plane, based on the tilt angle information obtained by the input means, a control means for controlling the measuring force of the measuring element with respect to the surface of the measured object, and, The control means sets the measuring force to P, the tilt angle to θ,
A surface shape measuring apparatus characterized by satisfying the following equation, where P ₀ is a measuring force when an inclination angle is 0. P = P ₀ / cos θ