WO1990001142A1

WO1990001142A1 - Method and apparatus for measuring the surface condition

Info

Publication number: WO1990001142A1
Application number: PCT/JP1989/000732
Authority: WO
Inventors: Yukio Ibe
Original assignee: Kabushiki Kaisha Ksp
Priority date: 1988-07-21
Filing date: 1989-07-21
Publication date: 1990-02-08
Also published as: JPH0232206A

Abstract

A method and an apparatus for measuring surface coarseness, ruggedness, scars, degree of oxidation, discoloration and the like of materials. The operation is carried out such that an intersecting point P of the optical axis of a source of light (1) and of the optical axis of a light-receiving element (2) is positioned on a plane (4a) that is to be measured and another operation is carried out to move the source of light (1) and the light-receiving element (2) along the spherical surface with the intersecting point P as a center over a predetermined range, until the detect output of the light-receiving element reaches a maximum value. Thus, measurement can be carried out under predetermined conditions at all times, and the measuring precision is greatly improved compared with that of the prior art.

Description

Ming E Measurement of surface condition

The present invention relates to a method for measuring the surface state of an object and an apparatus for performing the method. For example, the present invention relates to a method for measuring, confirming, and further discriminating a surface condition such as a surface roughness of a polished object, that is, a surface roughness. The present invention also relates to a method and an apparatus for detecting scratches generated on the surface of an object polished to a mirror surface, and confirming or discriminating the degree of oxidation or dirt on the surface of a substance. .

There are various methods for measuring or discriminating the unevenness, roughness, etc. of the object surface.However, the method of detecting and judging the reflected light beam of the light beam projected on the surface to be measured is simple and inexpensive. It is heavily used.

For example, as shown in the cross-sectional view of FIG. 1, a light source 1 for emitting a light beam la and a light receiving element 2 for detecting a reflected light beam lb are provided on the inner surface of a cup-shaped housing 3 as shown in the sectional view of FIG. It is fixed at a fixed angle and measures the object 4 under test. When is set, the distance L between the light source 1 and the light receiving element 2 and the surface 4a to be measured is made constant by the action of the housing 3.

This is as shown in the graph of FIG. 2, that is, the characteristic curve diagram of the distance L (relationship) between the light source 1 and the light receiving element 2 and the surface 4a to be measured and the output V (mV) of the light receiving element 2. The output of the light receiving element 2 is when the case 3 is set on the DUT 4 and the flat measured surface 4a coincides with the intersection P of the optical axis of the light source 1 and the optical axis of the light receiving element 2. In consideration of the maximum value, the surface state of the surface 4a to be measured is determined by comparing the value of the signal detected by the light receiving element 2 at that time with a known measured value of the surface state obtained in advance through experiments or the like. It is like that.

However, as shown in FIG. 3 _ (a), when there is a large unevenness 4b of the projected light beam la on the surface 4a to be measured, the distance from the light source 1 and the light receiving element 2 to the surface 4a to be measured is L changes. In addition, as shown in FIG. 3 (b), when the projection spot of the projected light beam la is an inclined surface 4c, the angle between the projected light beam la and the reflected light beam lb changes, and the light receiving element lb The amount of light incident on the device is greatly reduced. Therefore, the conditions are different from the case where the measured surface 4a is assumed to be flat, and it is complicated to evaluate the detection output of the light receiving element 2 and compare it with the reference value. Need As a result, the simplicity, which is an advantage of the method for measuring the surface state using such a light beam, is impaired. Disclosure of the invention

The present invention has been made to solve the above-mentioned problems, and the object thereof is to provide almost the same conditions regardless of the surface condition, such as unevenness or inclination of the surface to be measured, etc. In other words, the distance between the light source and the light receiving element and the surface to be measured is maintained at a constant value, and the desired measurement can be performed while maintaining the projection and reflection angles of the luminous flux on the surface to be measured at a constant value. It is to provide a method and an apparatus.

The purpose of the above is

In a method of projecting a light beam from a light source to a surface to be measured and detecting a reflected light beam by a light receiving element arranged at a fixed position with respect to the light source to measure a surface state,

As the light beam, a light beam obtained by turning on / off a light beam in the infrared region in a pulsed manner at a predetermined cycle is used.

Adjust the distance between the light source and the light-receiving element and the surface to be measured so that the surface to be measured coincides with the intersection of the two light beams of the light source and the light-receiving device arranged at a fixed position with respect to each other; and Move the light receiving element within a predetermined range along the spherical surface centered on the intersection point. The peak value of the output signal is held, and the maximum value of the obtained detection signal is compared with a known signal value relating to the surface condition. Is

A light source for projecting a light beam formed by turning on and off a light beam in an infrared region in a pulsed manner at a predetermined cycle toward a surface to be measured;

A light-receiving element for receiving a light beam reflected from the surface to be measured, a housing in which the light source and the light-receiving element are fixed such that their optical axes cross at a predetermined angle,

'' A drive mechanism that moves the housing close to and away from the surface to be measured,

A first rotation mechanism for rotating the housing around a horizontal U-axis passing through an intersection of both light sources and light-receiving elements, and intersecting the housing at a right angle with the u-axis at the intersection And a mechanism for rotating the housing itself about an angle bisector of the optical axis of the light source and the light receiving element as an axis. When,

A pulse generator that synchronizes and controls the on / off operation of the light source in the predetermined cycle and the operation of the gate path for passing the detection signal from the light receiving element;

A peak hold circuit that holds a peak value of a detection signal of the light receiving element that has passed through the gate circuit, An indicator for displaying the hold value of the beak hold circuit,

A beak update detection circuit that activates a desired annunciator when an update speed of a beak value held on the beak hold surface is a predetermined value or more;

The present invention can be implemented by a surface condition measuring device characterized by providing the above.

With such a measuring method and apparatus according to the present invention, the distance between the light source and the light receiving element and the surface to be measured is kept constant, and the projection and reflection angles of the luminous flux on the surface to be measured are kept constant. Since the measurement can always be performed under the same conditions regardless of the surface condition, such as the presence or absence of unevenness or inclination of the surface to be measured, the surface can be compared with a known measurement value of the same object. The measurement and discrimination of the state will be performed much more accurately than in the past. BRIEF DESCRIPTION OF THE FIGURES

Fig. 1 is an explanatory diagram of a conventional measuring device for surface condition, Fig. 2 is a graph showing characteristic curves of measurement results by the conventional measuring device shown in Fig. 1, and Figs. 3 (a) and (b) are FIG. 1 is an explanatory diagram showing the problems of the conventional measuring device shown in FIG. 1, and FIG. 4 is an explanatory diagram showing an apparatus for implementing the measuring method according to the present invention. FIG. 5 is an explanatory diagram showing an outline of a main part, FIG. 5 is an explanatory diagram showing an original material of the measuring method according to the present invention, and FIG. 6 is an electric circuit of an apparatus for performing the measuring method according to the present invention. FIG. 7 is a block diagram showing one embodiment of the present invention, FIG. 7 is a graph showing an example of a measurement result by the method according to the present invention, and FIG. 8 is a diagram for implementing the measuring method according to the present invention. FIG. 9 is a front view showing an embodiment of the apparatus, and FIG. 9 is a side view thereof. Best form for carrying out the invention

The details of the present invention will be specifically described below with reference to FIGS. 4 to 9.

Fig. 4 shows the main part of the apparatus for carrying out the measurement method according to the present invention.The light source 1 and the light receiving element 2 are arranged at a fixed angle on the inner wall of the cup-shaped housing 3A. The fixing is the same as that of the embodiment shown in FIG. 1, but the length of the hood of the housing 3A is configured to be shorter than the above L by £ and the optical axis of the light source 1 is set. P, the intersection of the axis of the projected light beam la from the light source 1 and the axis of the reflected light beam lb from the measured surface 4a when the detection output at the light receiving element 2 is maximized. It is configured such that P is formed further forward than the tip of the hood.

The support wheel 5 of the housing 3A is shown in FIG. 8 and FIG. As will be described later, the object to be measured 4 is held on a stand body head via a predetermined rotating mechanism, and the object 4 to be measured is located on the XY axis of the stand body bed provided immediately below the head. It is placed on a cross slide table, and a desired measurement site of the DUT 4 can be made to face the housing 3A by moving and positioning the XY cross slide table in two axes. In the above-mentioned stand body, the head to which the above-mentioned housing 3A is attached and the cross slide table are configured so as to be able to approach and separate in the vertical direction (the Z-axis direction). A rotary positioning table is provided between the loss slide table and the measured object 4 or between the cross slide table and the bed.

Thus, in the present invention, the positioning of the housing 3A and the measured object 4 in the Z 轴 direction so that the intersection point P is located on the surface 4a to be measured at the time of measurement, and the housing 3A itself Is moved within a predetermined range along a spherical surface centered at the intersection P, whereby the center axis A of the housing 3A passing through the intersection P always changes the normal direction of the surface 4a to be measured. As a result, the luminous flux from the light source 1 is always projected onto the surface 4a to be measured at a constant incident angle, so that the angle of reflection from the surface 4a to be measured is also constant, and It is designed so that measurements are always made under constant conditions. The movement of the housing 3A along the spherical surface around the intersection P is desirably performed by moving the housing 3A along the X-axis passing through the intersection P (or the U-axis parallel to this), as shown in FIG. ) Around the arrow M, and rotate along the arrow N about the Y-axis (or V-axis parallel to it) perpendicular to the X-axis at the intersection P. Achieved by:

In this way, at the time of measurement, the housing 3A is moved along the arrows M and N while the housing 3A is moved toward and away from the surface 4a to be measured, and the output of the light-receiving element 2 is constantly output during the operation. If the maximum value is detected, the intersection point P coincides with the surface 4a to be measured at the time when the maximum value is obtained, and the center line A of the housing 3A is located at the portion of the surface 4a to be measured. This indicates that the surface normal is measured and discriminated under constant conditions by comparing the maximum value with known measured values of the same object.

That is, it is possible to perform the measurement under the same condition even under various different situations, such as when the surface 4a to be measured has irregularities larger than the diameter of the light beam, an inclined portion, etc. In this way, it is possible to perform a comparative measurement of the surface condition such as the surface roughness and the presence or absence of scratches on a three-dimensional surface.

The hood of the housing 3A was shorter than the distance L between the light source 1 and the light receiving element 2 and the intersection P of their optical axes. This is to prevent the tip of the hood from colliding with the surface to be measured 4a during the rotation operation of 3A as described above.

However, in the above case, the portion of the luminous flux projection point P on the surface 4a to be measured is exposed to ambient environmental light, so the wavelength of the luminous flux for measurement from the light source 1 is set in the infrared region. Needless to say, it is necessary to perform other distribution.

Next, with reference to FIG. 6, one embodiment of an electric circuit of an apparatus for performing the measuring method according to the present invention will be described. In the figure, 6 is the light source 1 and the light receiving element 2. A light source 1 emits a luminous flux having a wavelength in the infrared region described above, and a predetermined frequency, that is, a commercial frequency and its harmonics by a pulse generator 7. The switching element 8 is turned on and off at a frequency different from that of, for example, 270 Hz to emit a pulsed light beam.

The pulse-shaped light beam emitted from the light source 1 and reflected on the surface to be measured is detected by the light receiving element 2, and the detection signal passes through a buffer circuit 9 and is controlled by the pulse generator 7 by the pulse generator 7. The output through the path 10 removes the above-mentioned disturbance of the detected waveform due to the ambient light and the overshooting / undershooting of the detected square wave. As a result, in the present invention, the housing 3 A is It is sufficient that the light receiving element 2 and the light receiving element 2 can be set at predetermined projection and light reception angle positions, and the light receiving element 2 does not need to have a function as a special light shield for environmental light.

11 is an operational amplifier for amplifying the output of the gate circuit 10 at a predetermined magnification, 12 is a beak hold circuit having an input terminal and a reset input terminal for the output of the amplifier 11, and an AZD core having a hold key. The beak value of the detection signal obtained by the light receiving element 2 is displayed on the desired analog meter or digital LCD display 14 via the inverter 13, while peak update detection having a subdivision circuit and a comparator circuit is performed. When the increase rate of the peak value detected by the pulse generator 7 of the beak hold circuit 12 for each frequency by the circuit 15 is equal to or higher than a predetermined value, the beacon circuit 12 is notified by a light, sound, vibration, or the like by a notifier 16. The distance adjustment of the sensor section 6 (housing 3A) to the surface to be measured by manual or other means and the adjustment of the inclination angle of the support shaft of the housing 3A can be performed without the display unit 14. .

Reference numeral 17 denotes a switch for switching between measurement and hold, which is measured by turning on the switch, that is, in such a manner that the light reflected from the light receiving element 2 of the light projected from the light source 1 to the surface 4a to be measured is maximized. After adjusting the distance and inclination of the housing 3A with respect to the surface 4a to be measured, and then off-holding, the peak hole The detected beak value of the circuit path is held by the A / D converter 13, the beak hold circuit 12 is reset by a hold signal input via a delay circuit (not shown), and the LCD display 14 is reset. The displayed beak value will continue to be displayed.

As described above, the measuring device according to the present invention includes the sensor unit 6 movably supported within a predetermined range along a spherical surface centered on the intersection P of the optical axis of the light source 1 and the light receiving element 2. The operation of adjusting the distance to the surface 4a to be measured with respect to the housing 3A so that the intersection point P is on the measurement surface, and the center axis A of the housing 3A in the direction normal to the surface to be measured When the angle adjustment operation is performed before and after the measured position at the measured position, the display 14 or the annunciator is set so that the detection signal of the light receiving element of the sensor unit 6 is maximized. The measurement value (intensity of reflected light, that is, the reflected light intensity, ie, the distance from the light source and the light receiving element to the surface to be measured, and the angle of incidence and reflection of the luminous flux on the surface to be measured) is always constant. (Detected output value of the light-receiving element) is obtained. Measurements of the surfaces condition by comparing child with known measurement value each, in which determination is made possible in a more accurate state.

FIG. 7 is a characteristic curve diagram showing an example of the measurement results obtained by the measurement method according to the present invention. Surface roughness // m R max), with the vertical axis representing the detection output (V) on an equally spaced scale and the horizontal axis representing the surface roughness (rnR max) on a logarithmic scale Therefore, the relationship is almost inversely proportional.

From this characteristic curve, it is possible to detect cracks and other scratches on the surface of a substance polished to a mirror surface with a size of submicron order or more, according to the measurement method of the present invention. In the range where the present invention is generally applied as a simple measuring method, a stylus type surface roughness meter having a surface roughness of 1 m and a surface roughness of 2 m It can be used as one that can find a significant difference from the one.

Further, according to the measurement method of the present invention, it was possible to determine the presence or absence of gloss, the presence or absence of a different color state, and the like at each measurement position in a complex shape such as a denture of a dental material. 8 and 9 are a front view and a side view showing a schematic configuration of one embodiment of a mechanical device for performing the measuring method according to the present invention, wherein 21 is a bed for supporting the entire device, Reference numeral 22 denotes a saddle supported so as to be movable in the Y-axis direction. Reference numeral 23 denotes a table supported by the saddle 22 so as to be slidable in a direction (X-axis direction) perpendicular to the moving direction. 24 indicates a drive unit for the saddle 22 in the Y-axis direction, and 25. An axial drive. Reference numeral 26 denotes a swivel provided on the upper surface of the table 23. The swivel 26 has the object 4 to be measured mounted thereon. The swivel 26 passes through the center of the swivel 26 and vertically intersects the table 23 around Z 23. (For example, the W axis), and can be moved by a driving device 37. Reference numeral 3 denotes a housing of the sensor unit, 27 denotes a head for supporting the support shaft 5 of the housing 3 _c 28 rotationally positions the housing 3 around the shaft of the support shaft 5 The device 29 is a head table for supporting the head 27 and is movably held on the arm 30. The arm 30 forms a part of a circular orbit such that the head table 29 rotates about a U-junction (parallel to the X-junction) passing through the intersection P of the housing 3, For example, a tooth shape (omitted in the figure) is engraved on the inner periphery to form a sector gear, which engages with the small gear or worm provided on the head table, and a drive provided on the head table 29 similarly. By rotating the small gear or micro-ohm by the device 31, the head table 29 is rotated about the U 轴 along the arc trajectory of the arm 30.

On the other hand, reference numeral 32 denotes a turntable which supports the arm 30 so as to be movable on the slide table 33. The center of rotation (V-axis) of the turntable 32 is parallel to Y, and is an extension line thereof. Is the light source 1 and The arm 30 is configured to pass through the intersection point P of the above two optical axes, and the entire arm 30 rotates around the V axis. Numeral 34 is a drive unit for the surface turning table 32, and numeral 35 is a core supporting the slide table 33 so as to be slidable in a vertical axis (z) direction perpendicular to a horizontal plane containing the X and γ axes. Reference numeral 36 denotes a driving device for moving the slide table 33 in the Z-axis direction.

Reference numeral 28 denotes a device for rotating the housing 3 around its central axis A (that is, the bisector of the angle formed by the optical axes of the light source and the light receiving element). In the case where the surface has anisotropic light reflection characteristics due to, for example, its polishing direction, the housing 3 is turned around its center axis A, and the light receiving element generates the maximum amount of light. It is positioned so that it can be obtained.

Thus, at the time of measurement, the DUT 4 is positioned and attached to a predetermined position on the swivel 26, and the driving devices 24, 25, and 37 are manually or manually operated by a numerical control device to be measured. The measurement part is usually positioned directly below the housing 3 and the head 27 at the origin position, and then the distance of the housing 3 to the measured surface 4a by moving the driving device 36 manually or in the Z-axis direction by a numerical controller. Adjustment and adjustment of tilt angle of U-axis and V-axis movement by manual or numerical control of drives 31 and 34 And the rotation of the housing 3 around its center line by the image transfer device 28 is performed while monitoring the notification by the detection of the peak detection circuit 15.

As the rotating mechanism of the casing 3 around the U axis and the V axis, for example, a shaft rotating link mechanism described in JP-A-48-2287 and JP-A-48-2383 is used. Of course, other known configurations can be used.

As described above, according to the present invention, the distance between the light source and the light receiving element and the surface to be measured is maintained at a predetermined constant value, and the projection angle of the luminous flux on the surface to be measured is always constant with respect to the surface to be measured. Since the measurement is performed so that it is constant, the measured value that is the detection output value of the light-receiving element is always obtained under constant conditions, and the surface condition is measured by comparing with the known measured value of the same substance. Discrimination can be made much more accurately than in the past. ,

Further, according to the present invention, since the sensor is combined with the peak hold circuit as described above, it does not operate with an output less than the display on the display, and the measurer does not need to operate the sensor at the position to be measured. I can minimize three-dimensional movement with respect to the housing

It should be noted that the present invention is not limited to the above-described embodiments, and within the scope of the present invention, those skilled in the art will appreciate from the above description. It is intended to cover all readily conceivable modifications, and the scope of the invention should be determined only by reference to the appended claims. Availability on

The method and apparatus for measuring the surface state according to the present invention include, for example, the unevenness of the surface of various polished objects, surface roughness, presence or absence of scratches, the degree of oxidation of the surface, and the degree of discoloration. It is most suitable and widely used for checking and discriminating. .

Claims

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1) A method in which a light beam is projected from a light source onto a surface to be measured, and the reflected light beam is detected by a light receiving element arranged at a fixed position with respect to the light source to measure a surface state.

As the light beam, a light beam obtained by turning on and off a light beam in the infrared region in a pulsed manner at a predetermined cycle is used.

Adjust the distance between the light source and the light receiving element and the surface to be measured so that the surface to be measured coincides with the intersection of the two optical axes of the light source and the light receiving element arranged at a fixed position with respect to each other; and Move the light receiving element within a predetermined range along the spherical surface centered on the intersection. ゝ Hold the peak of the detection signal of the reflected light beam by the light receiving element, and determine the maximum value of the obtained detection signal as the surface condition. A method for measuring a surface condition, comprising comparing with a known signal value for a surface.

2) A light source for projecting a light beam formed by turning on and off a light beam in the infrared region in a pulsed manner at a predetermined cycle toward the surface to be measured, a light receiving element for receiving a light beam reflected from the surface to be measured, A housing comprising a light source and a light receiving element fixed so that their optical axes cross at a predetermined angle;

Driving motion that moves the above housing close to and away from the surface to be measured 8 mechanisms and

A first planar motion mechanism for rotating the housing around a horizontal U-axis passing through the intersection of the optical axes of the light source and the light receiving element; and intersecting the housing at right angles to the U-axis at the intersection. And a mechanism for rotating the housing itself about the bisector of the angle formed by the optical axes of the light source and the light receiving element. When,

A pulse generator that controls the on / off operation of the light source in the predetermined cycle in synchronization with the operation of the gate circuit that passes the detection signal from the light receiving element;

A beak hold circuit for holding a peak value of a detection signal of the light receiving element that has passed through the gate circuit,

An indicator for displaying the hold value of the beak hold circuit,

A beak update detection circuit that activates a desired alarm when an update speed of a beak value held by the beak hold circuit is equal to or higher than a predetermined value;

A surface state measuring device characterized by comprising: