JPS58223013A - Apparatus for measuring surface shape of body - Google Patents

Abstract

PURPOSE:To measure the surface shape of a body, whose light reflectivity is small such as a video disk, by arranging a contact type displacement detector on the measuring surface of a material to be measured, which is rotatably supported, and detecting the moving position and displaced value. CONSTITUTION:When the undualtion of a disk 2 in the circumferential direction is measured, a displacement detector 3 is contacted with an arbitrary position on the disk surface. When a start button is operated, a motor 16 starts a constant speed rotation at a speed lower than a rated speed when the disk is used. At this time, angular pulses BS from a rotary encider 18 and a signal AS detected by the displacement detector 3 are introduced in an operation control part 5. When the undulation of the disk 2 in the radial direction is measured, the displacement detector 3 is set at the innermost position on the surface of the disk 2. When the start button is operated, a motor 40 starts the rotation, the displacement detector is moved to the outer periphery side from the inner side of the disk 2 and detects the undulation of the surface of the disk 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an improvement in an object surface shape measuring device for measuring the surface shape, such as flatness, of an object whose surface has a low light reflectance, such as a video disc. .

[Technical background of the invention]

Conventionally, as a means of measuring the unevenness of the surface of an object, for example, a coherent beam of light or a beam is irradiated onto the measurement surface and the amount of unevenness is determined from the change in the reflected image.
There is a method that irradiates light through a grating plate and determines the rough state of the unevenness from the degree of deformation of the reflected virtual image. However, since all of these measurement methods determine the unevenness based on the state of light reflection on the measurement surface, when measuring objects with low light reflectance on the surface, such as video discs, Accurate measurements cannot be made because the light level is significantly reduced.

Therefore, in the past, for example, a metallurgical microscope or a scanning microscope was used to obtain an enlarged image of a specified minute area, and from this image the unevenness of the object surface was determined by shape, or a capacitive displacement meter was used. Detecting surface irregularities.

[Problems with background technology]

However, with the former type of microscope, the measurable range is limited to a minute area, so it is difficult to know the overall unevenness state, and it is difficult to know the overall unevenness state. Since the operation has to be repeated many times, it has the disadvantage that measurement requires a lot of time and effort. Furthermore, in this case, if shape discrimination were to be performed automatically, the image processing would be complicated and the equipment would be very expensive.On the other hand, the latter method using a capacitive displacement meter, Since the resolution is determined by the size of each sensor, the measurement accuracy is generally low, and there is a drawback that only rough irregularities can be obtained.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface shape measuring device for an object that can accurately and continuously measure the surface displacement of an object even if the light reflectance is low.

[Summary of the invention]

In order to achieve the above object, the present invention has an object to be measured rotatably supported on a support base, and a contact type displacement detector is arranged opposite to the measurement surface of the object to be measured, and in this state, the displacement is detected. After controlling the support mechanism of the device to position the displacement detector, the object to be measured is rotated at a constant speed, or the object to be measured is stopped and the displacement detector is moved in the radial direction of the object to be measured. In particular, it is designed to detect the displacement characteristics of the measurement surface of the object to be measured.

[Embodiments of the invention]

FIG. 1 is a schematic configuration diagram of a surface profile measuring apparatus according to an embodiment of the present invention. Contact type displacement detectors 3 and 1 are arranged opposite to each other on the surface. It is composed of a support mechanism 4 that supports the displacement detector 3 so as to be movable in the gravity direction and the horizontal direction, an arithmetic control section 5, and a display section 6.

The support stand 1 has a turntable 11 on which a video disc 2 is placed, and a shaft 12 of this turntable 11.
are connected to a drive motor 16 via a force, a ring 13, an electromagnetic clutch 14 and a timing belt 15, respectively.

Further, a rotary encoder 18 is connected to the shaft 121C via a gear mechanism 17 consisting of two gears having the same number of teeth. This rotary encoder 18 is for detecting the rotation angle of the video disc 2, and emits, for example, 512 angle pulses each time the video disc 2 rotates once. Note that 19 is a vacuum tube for sucking the video disc 2 onto the turntable 1.

The displacement detector 3 has a measuring element 34 made of an electric micrometer attached to an XY stage 33 configured to be able to move minutely with micrometer heads 31 and 32, as shown in FIGS. 2(a) and 2(b), for example. By operating the micrometer heads 31 and 32, the position of the probe 34 can be finely adjusted in the vertical and horizontal directions.

The support mechanism 4 has a support column 43 equipped with a feed screw 42 that is rotated by the handle 4 inside.
A support arm 43 that moves in the vertical direction is attached. Inside this support arm 43, a handle 44, a feed screw 46 rotated by a drive motor 40 via a shikarag ring 45, and a pair of guide arms 47- are provided. An L-shaped 7-mm 48 having the displacement detector 3 attached to its tip is screwed onto the feed screw 46. By rotating 46, it reciprocates in the horizontal direction while being guided by a guide arm 47.

A linear encoder 49 is installed on the support arm 43, and the linear encoder 49 detects the movement position of the upward arm 48 and the position of the displacement detector 3.

Calculation control unit 5try-N As shown in FIG. 3, a microprocessor 51 that controls the operation of each mechanical unit and calculates measured values, and a displacement detection signal (analog signal) output from the displacement detector 3. a displacement detection signal input circuit 52 for introducing AS into the microprocessor 51;
A device/zoles C8 consisting of an angle pulse input circuit 53 that introduces the angle/base pulse BS generated from the rotary encoder 18 into the microprocessor 51 and the linear encoder 49 is connected to the microgrosse.
1, and an input period designation circuit 5 for designating the input period of the displacement detection signal As.
5, and an interface circuit 56 for interfacing signals from each of these circuits to the microprocessor 51.
and an interface circuit 57 for interfacing signals to the display unit 6 from which the microgross unit 51 is connected.

The displacement detection signal input circuit 52 amplifies the displacement detection signal AS with an amplifier 52a, sample-holds it with a sample bold circuit 52b, and then converts it into a digital signal with a ψ converter 52e.

The angle pulse input circuit 53 uses a frequency divider 53h to divide the angle pulse BS into an appropriate number depending on the type of disk to be measured, and also counts the angle pulse BS using a counter 53b to calculate the counted value. It is generated as angular position information when measuring the displacement of the disk in the radial direction.

The input period designation circuit 55 includes a switch 55a for specifying the measurement range in the radial direction when measuring displacement in the radial force direction of the disk, and a rotation start position (initial value) of the disk when measuring displacement in the circumferential direction of the disk. and an initial pulse generating section 55b for emitting a pulse specifying the ! Microswitch (not shown) to detect
It is generated from.

Further, a signal for operating the initial/4' pulse generating section 65b is generated from a microswitch that outputs 1* from an arbitrary point on the turntable 1.

The display section 6 is composed of, for example, a cathode ray tube (CRT) display, an X-Y block, or the like.

Next, the operation of the apparatus configured as described above will be explained according to the operating procedure. First, prior to measurement, the frequency division number of the frequency divider 53a of the angle pulse input circuit 53 is set according to the type of the measurement disk, and then the disk 2, which is the object to be measured, is set on the turntable 11.

In this state, when measuring the circumferential irregularities and ridges of the disk 2, first use the handle 41 of the support mechanism 4.
The support arm 43 is lowered by operating the handle 4.
4 to move the support arm 43 in the horizontal direction, the displacement detector 3 is set in contact with an arbitrary position on the disk surface. At this time, fine adjustment of the set position of the displacement detector 3 is performed by operating the micrometer head 30, 31 of the displacement detector 3.

Then, in this state, operate the start button (not shown). Then, a drive signal is generated from the microprocessor 51 to the drive motor 16, and the motor 16 starts rotating at a constant speed lower than the rated rotation speed when the disk is used. When rotation starts in this way, the rotary encoder 18
An angle pulse BS is generated from the angle pulse BS, and a displacement of the disk 2 in the circumferential direction is detected by the displacement detector 3, and its detection signal As is introduced into the arithmetic control section 5. As a result, in the calculation control section 5, the microprocessor 51 calculates the displacement detection signal As introduced while the disk 2 rotates once and while the angle pulse BS for one rotation of the disc 2 is input. A curve and an acceleration curve are respectively determined.

Here, the flat curve is obtained by sampling and holding the displacement detection signal As for each angle pulse BS. On the other hand, the acceleration curve begins with the displacement detection signal As
18 of the measured disk 2 by Fourier transforming
Calculate the number n of undulations, and calculate the number n of undulations and the rated frequency N [r-p
−all and f= N X n [:Hz] −(1
) to find the frequency f.

Then, from this frequency f and the half amplitude a of the displacement obtained from the flat curve, the acceleration of change in displacement G occurring in the direction orthogonal to the surface of the disk 2 is calculated as G = a x (2fff)
/ 980 CG)・, ...(2) Calculate as follows. However, 980 is a conversion constant for matching dimensions.

The calculated value obtained in this way is calculated by microgrosse 51, and in the case of a flat curve, the horizontal axis is the rotation angle θ [degrees] of the disk 2.
By taking the displacement D [μm] on the vertical axis, it can be displayed, for example, in the X-Y f lock. FIG. 4 shows an example of the display result. On the other hand, in the case of an acceleration curve, the horizontal axis is the frequency! [:H2) and the displacement axis a [μm] is taken as the vertical axis, so that it is displayed on, for example, a CRT display. In this case, a standard curve obtained in advance is displayed on the display gray together with the measurement curve in order to facilitate the determination of the quality of the measurement result.

FIG. 5 shows an example of the display results, in which I indicates the measured curve and ■ indicates the standard curve, respectively.

On the other hand, when measuring the radial ridge of the disk 2, first manually rotate the turntable 11 to align it with the rotation start position, and in this state generate a motor drive control signal from the microgrosse 51. Rotate the drive motor 16 and set the measurement 1'□ and □ positions. Then, by operating the handle 41, the displacement detector 3 is set at the innermost position on the surface of the disk 2, and the preparation is completed.

When the start getter is operated in this state, a drive control signal is issued from the microgrosse 51 to the drive motor 40, and the motor 40 starts rotating.As a result, the displacement detector 3 moves from the inner circumferential side of the disk 2. It moves toward the outer circumferential side and detects the ridges on the surface of the disk 2. When the displacement detection signal is output from the displacement detector 3, the arithmetic control section 5 introduces the displacement detection signal AS to the microprocessor 51 together with the device detection signal C8 constituted by the linear encoder 49. In addition, at this time, microgloss,
The input period designation circuit 51 introduces each of the above-mentioned signals only during the period designated by the switch 55a of the input period designation circuit 55. Then, the microprocessor 51 samples and holds the displacement detection signal AS according to the position detection signal C8, takes this value on the vertical axis, and plots the disk radius R [m+] converted from the position detection signal C8 on the horizontal axis. Deploy. Then, this information is output and displayed on, for example, an X-Y graph. A flat curve in the radial direction of the disc 2 is thus obtained. FIG. 6 shows an example of the display result of this flat curve.

In this way, the device of this embodiment uses the contact type displacement detector 3 and moves the displacement detector 3 and the disk 2 relatively, thereby detecting the ridges on the surface of the disk 2. By measuring the displacement of an object having a low light reflectance, such as a video disk, displacement can be detected with high accuracy, and there is an advantage that the displacement can be detected continuously. In addition, since the displacement detection signal As and the output signals of each encoder are not complicated signals like video signals, calculation processing can be performed in an extremely short time and with a simple configuration, making it possible to use high-performance and inexpensive equipment. can be provided.

Note that the present invention is not limited to the above embodiments.

For example, in addition to the disk as the object to be measured, the present invention may be applied to measuring the surface condition of other products that require flatness or products that have specific irregularities. The configurations of the displacement detector, the support base, the support mechanism, and the operation of the arithmetic control unit can be modified in various ways without departing from the gist of the present invention.

〔Effect of the invention〕

As described in detail above, the present invention includes rotatably supporting an object to be measured on a support base, and arranging a contact type displacement detector facing the measurement surface of the object to be measured, and in this state, the displacement detector or The surface shape of the object to be measured is measured by moving the object to be measured relatively and detecting the movement position and the detected displacement value.

Therefore, according to the present invention, it is possible to provide a surface shape measuring device for an object that can accurately and continuously measure the surface displacement of an object even if the object has a low light reflectance.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a surface profile measuring device according to an embodiment of the present invention, Fig. 2 (a) and (b) show the configuration of a displacement detector of the same device, and (a) is a side view. , (b) is a plan view, FIG. 3 is a block diagram showing the configuration of the arithmetic control section of the device shown in FIG. 1, and FIGS. 4 to 6 are obtained by using the device shown in FIG. 1. It is a characteristic diagram which shows the example of a display of a measurement result. DESCRIPTION OF SYMBOLS 1... Support stand, 2... Disk, 3... Displacement detector, 4... Support mechanism, 5... Arithmetic control unit, 6...
Display unit, 16.40... Drive motor, 18... Rotary encoder: I-da, 49... Linear encoder, 51
...Microprocessor, 52...Displacement detection signal input circuit, 53...Angle pulse input circuit, 54...
Position signal input circuit, 55...Input period designation circuit. Applicant's representative Patent attorney Takehiko Suzue Figure 1 Figure 2 (a) (b) Figure 4 Figure 5 [H2] Figure 6

Claims (2)

[Claims] (1) A displacement detector that rotatably supports an object to be measured and that contacts the measurement surface of the object to detect the amount of unevenness of the measurement surface, and this displacement detector is movable. a support mechanism that supports the object to be measured and moves it in contact with the measurement surface of the object in the rotational radial direction; a movement amount detector provided on the support mechanism that detects the amount of movement of the displacement detector; What is claimed is: 1. A surface shape measuring device for an object, comprising: an arithmetic control section that determines flatness characteristics at the measurement position based on detection results of an angle detector, a movement amount detector, and a displacement detector. (2) The arithmetic control unit calculates, as flatness characteristics, the surface displacement characteristics of the measuring object in the rotational circumferential direction, the surface displacement characteristics of the measuring object in the rotational radial direction, and the above-mentioned surface displacement characteristics when converted to the rated rotation of the measuring object. An apparatus for measuring the surface shape of an object according to claim 1, wherein the acceleration characteristic of change in the plane direction of the surface of the object to be measured is determined.