JPS5973717A - Device for measuring surface undulation of body - Google Patents

Abstract

PURPOSE:To measure undulating shapes fully automatically and highly accurately and to perform judgement as to whether a material to be measured agrees with a specification or not simply by a display means, by sucking and fixing the material to be measured, removing the error caused by the slant of a rotary table by an error correcting means, and performing the comparison of the spectrum with respect to a frequency and a specification curve and the display of the result. CONSTITUTION:A video disk is sucked and fixed to a turn table. The surface displacement of the video disk in the circumferential direction is detected by a displacement detector. The outputted surface displacement detected signal AS is converted into a digital value. The digital value is sent to a CPU551 in a data analysis part 55, and written into a memory part 54. The output data from the memory part 54 is corrected by an error correcting means 552. A undulation number (n) is computed by Fourier transformation. A frequency (f) if obtained from the undulation number (n) and a rated frequency N when the video disk 2 is actually used. A spectrum of the surface displacement with respect to the frequency (f) with an amplitude alpha on one side is obtained. The obtained data is stored in an image memory 561 and a plotter memory 563.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a surface undulation measuring device for measuring the surface undulation shape of an object such as a high-density information-recorded video disk.
In particular, the present invention relates to improvements in calculation means for calculating the shape of surface undulations of objects, and to an apparatus for measuring surface undulations of objects that can determine whether or not the object conforms to specific standards.

[Technical background of the invention]

Conventionally, standards with margins were set for video discs based on the characteristics and standards of video disc playback players, but it is now possible to electrically measure whether a video disc meets the same standards as the disc. There is no means for determining the undulation shape of the video disc.90 Therefore, conventionally, humans play the video disc and comprehensively judge the ridge shape of the video disc from the images and sounds on the CRT screen obtained by the reproduction. There is a method that uses a capacitive displacement meter to measure the surface wobbling of a video disc on a player.

[Problems with background technology]

However, although the former judgment means is able to grasp the shape of the dog's ridges because it is judged by a human, it is difficult to use it as a uniform quality judgment means when shipping as a product. However, it still has the drawback that it requires a lot of time and effort to make a determination.

Next, the latter method using a capacitive displacement meter generally has low accuracy because its resolution is determined by the size of each sensor, and can only obtain a rough undulation shape. Originally, when determining the surface ridge shape of an object, it is not possible to accurately determine the ridge shape of a single video disc unless the Q-worth vector with respect to frequency and the acceleration are determined. It was difficult to calculate the acceleration of Furthermore, what is common to both is that even if a video disc is determined to be non-standard from a general point of view,
It was not possible to determine at what stage of the disk manufacturing process this occurred.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and is an object that can measure the undulation shape fully automatically and with high precision without requiring any skill, and can also determine whether or not the simple fist conforms to the standard using a display means. The object of the present invention is to provide a surface ridge measuring device.

[Summary of the invention]

The present invention fixes an object to be measured on a rotary table by vacuum suction, and a displacement detector positioned by a support mechanism is brought into contact with the surface of the object to be measured, and the object to be measured is rotated by the rotation of the rotary table. Using the time element and the surface displacement data of the displacement detector to determine the surface undulation shape of the object to be measured, and from the surface undulation shape signal with the time element to obtain the power spectrum versus frequency to determine the acceleration curve; Furthermore, the present invention is an apparatus for measuring surface ridges of an object, which displays or records the four-worth vector and the standard curve on a CRT or block to determine whether the object to be measured conforms to the standard.

[Embodiments of the invention]

FIGS. 1 and 2 are configuration diagrams showing one embodiment of the present invention. Note that FIG. 1 is a block diagram of a surface displacement detection mechanism of an object to be measured, and FIG. 2 is a block diagram of a signal processing that processes and displays signals obtained by the surface displacement detection mechanism. The surface displacement detection mechanism consists of a support stand 1 for a video disk as an object to be measured, a contact type displacement detector 3 disposed opposite to the surface of a video disk 2 supported by this support stand 1, and It is comprised of a support mechanism 4 that supports the displacement detector 3 movably in the direction of gravity and in the horizontal direction.

The support stand 1 has a turntable 11 on which the video disc 2 is fixedly placed at the center of the rotating shaft by a tapered bin 10 (also called a centering stopper), and the shaft 12 of the turntable 11 is connected to a coupling 13 and an electromagnetic clutch. 1
4 and a timing belt 15, respectively, to a drive motor 16. Further, a rotary encoder 18 is connected to the shaft 12 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 every time the video disc 2 rotates once. Further, 19 is a vacuum tube for attracting the video disc 2 to the turntable 11. This vacuum suction means is provided with small holes at regular intervals in the radial direction of the turntable 11, and inside the shaft 12 to allow air to circulate between the turntable 11 and the vacuum tube 19. Air ventilation holes are provided.

The displacement detector 3 is, for example, a micrometer head 31.3.
2, a measuring element 34 consisting of an electric micrometer is attached to an XY stage 33 configured to be able to move finely.
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 which is rotated by the nozzle 41 in the interior thereof. A support arm 43 that moves in the vertical direction is attached. A feed screw 46 and a pair of guide arms 47 are provided inside the support arm 43 and are rotated by a nozzle 44 and a drive motor 40 via a υ coupling 45. An L-shaped arm 48 having the displacement detector 3 attached to its tip is screwed onto the feed screw 46, and the L-shaped arm 48 is guided by rotating the feed screw 46 with the handle 44. It is designed to reciprocate horizontally while being guided by an 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 tab displacement detector 3.

Next, the signal processing system shown in FIG. An A-D converter 53 having, for example, a 12-bit configuration that converts As into a digital value, a memory section 54 such as a RAM that stores the digital value of this A-D converter 53, and the encoder l? When the digital conversion end signal IOC is input from the A-D converter 53, which digitally converts the surface displacement detection signal As for each output pulse of It consists of a data analysis calculation section 55 that obtains an acceleration curve, and a display judgment section 56 that has a pass/fail judgment function.

The data analysis calculation unit 55 is a calculation control unit (hereinafter, CP
551 (commonly referred to as U), and an error correction means 552 that performs single peak correction of the output data of the memory unit 54 according to the program of the CPU 551 to obtain a ridged shape as shown in FIG.
Fourier transform means 55 transforms the signal from which errors have been removed by this means 552 to obtain a spectrum of half amplitude α of surface displacement with respect to frequency f as shown in FIG.
3, an acceleration calculating means 554 for obtaining a Yakaro velocity curve using the frequency f obtained by the Fourier transform means 553, and standard curve data 555 stored in the memory of the CPU 551 in advance. The display determination section 56
is an image memory 56 that stores the waviness shape data, acceleration curve data including a spectrum, and standard curve data 555 obtained by the error correction means 552 as image data.
1, and a CRT 56 that reads and displays image data from an image memory 56 by operating a keyboard (not shown) or the like.
2, a memo 563 for storing various data, and a plotter 564 for plotting data in the block memory 563 according to an external command.

Next, the operation of the apparatus configured as above will be explained.

Prior to measurement, first, the video disc 2 is set at the center of the rotation axis of the turntable 11 using the chip/mother pin 10. In this state, the handle 41 of the support mechanism 4 is operated to lower the support arm 43, and the handle 44 is operated to move the support arm 43 in the horizontal direction, thereby moving the displacement detector 3 anywhere on the disk surface. Set it so that it is in contact with the position. At this time, fine adjustment of the set position of the displacement detector 30 is performed by operating the micrometer head 30, 31 of the displacement detector 3. moreover,
A vacuum engine (not shown) is driven to vacuum-adsorb the video disc 10 onto the turntable.

When the measurement preparation is completed as described above, the star)yf
methane (not shown). Then, the drive motor 16 rotates at a required rotational speed, and along with this rotation, the rotary encoder 18 generates an angle angle B8, and the displacement detector 3 Surface displacement is detected and a surface displacement detection signal As is output. Note that the rotary encoder 18 outputs 512 angles A' for one rotation of the video disc 2.
Luz BS is now generated. Therefore, the surface displacement detection signal As is amplified by the preamplifier 52 and then A-
The angle pulse BS is sent to the D converter 53, and serves as a conversion start signal for the A/D converter 53 as a pulse having a time element. Here, the A, -D converter 53 outputs a surface displacement detection signal A which is an analog value amplified by the preamplifier 52 in synchronization with the angle pulse BS from the rotary encoder 18.
s into a digital value, and after the A-D conversion is completed, the conversion completion signal goc is sent to the CPU 5 of the data analysis calculation unit 55.
51. Therefore, the CPU 5' 51 grasps the time element from the conversion end signal EOC, and gives a command to sequentially store the A-D converted data in the memory section 54.
It's supposed to be. In this way, rotary encoder 1
When 512 points of data corresponding to the rotation of the video disc are sampled into the memory section 54 in synchronization with the output pulses of 8, the error correction means 552 of the output data of the memory section 54 is first performed according to the program of the CPU 551.

This correction means corresponds to the eccentricity calculation of roundness according to JISBO607, and calculates the time grasped by the CPU 551 by subtracting the DC component error, the fundamental wave component error, and the sine component error from the output detector of the memory unit 54. A ridge 9 shape signal with the error removed as shown in FIG.
53 and image memory 561, block memory 56
Sent to 3. In FIG. 3, the horizontal axis represents the rotation angle θ of the video disc 2, and the vertical axis represents the surface displacement. Therefore, the ridge shape signal from which the error has been removed by the error correction means 552 is the same (Fourier transform is performed according to the program of the CPU 551. This is the Fourier transform means 553 shown in the figure. Calculate the number n of ridges per revolution, and calculate the number n of ridges and the rated frequency N when the video disc 2 is actually used.
The frequency 1 is determined from , and the spectrum of the half amplitude α of the surface displacement with respect to the frequency f is determined as shown in FIG. Note that the acceleration surface mG can be easily determined from the frequency f and the half amplitude α of the surface displacement.

G=α×(2πf)2/98°, where 980 is a conversion constant for matching dimensions.

The data obtained by the calculation in this manner is stored in the image memory 561 and the plotter memory 563, respectively, in correspondence with the position data indicated by the angle pulse BS. Note that it is also possible to turn on the print or display mode using an external switch and store each data in either the image memory 561 or the plotter memory 563. In addition, when only raw data is required, the error correction means 55
By operating a switch, it is possible to easily store only the output of No. 2 or, if acceleration data is required, only the acceleration curve including the spectrum in the image memory 561 or the plotter memory 563. As mentioned above, in the display mode, the image is read from the image memory 561 and displayed on the CRT.
562 and when in print mode! Extract data from rotter memory 563 and block it.
564.

Furthermore, when a judgment command is given to the keyboard of the CRT 562, the spectrum and standard curve data 555 obtained by Fourier transformation are read out from the image memory 561 and displayed on the CRT 562 as shown in FIG.
It can be immediately determined whether the half amplitude α of the surface displacement falls within the standard C shown as the standard curve data 555. In Figure 4,
At 48Hz, the half amplitude α of surface displacement is 0.1591
(11 m) and can be determined to be out of standard.

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

The calculation for determining acceleration from frequency and displacement can be applied as is to other methods for determining similar cross-sectional shapes and accelerations based on digital or analog displacement inputs. For example, video
Displacement of the audio or audio signal train (deviation of track from perfect circle) can also be analyzed.

〔Effect of the invention〕

As described in detail above, according to the present invention, the object to be measured on the rotary table is set above the center of rotation using a tapered bin and is fixed by suction by the vacuum suction means, so that the ridged shape of the object to be measured is enhanced. It can be measured with precision. Furthermore, since the error correction means removes errors caused by rotation and table inclination, the undulation shape can be measured accurately in this respect as well. In addition, by comparing the display of the spectrum versus frequency with the standard curve, it is easy to judge the object to be measured, and it is possible to obtain a product of consistent quality. This makes it easy to identify the cause of problems that occur, and contributes to process improvements.

Furthermore, since the measurement is performed on a single object to be measured in terms of actual use, it is possible to provide an apparatus for measuring surface ridges of an object that has various effects such as making it easier to take measures when a problem occurs in the object to be measured.

[Brief explanation of drawings]

1 to 4 are shown to explain one embodiment of the device of the present invention, and FIG. 1 is a configuration diagram of the mechanical system of the device;
FIG. 2 is a block diagram of a signal processing system and a display determination section, FIG. 3 is a diagram showing a surface waviness shape, and FIG. 4 is a diagram showing a display determination state. DESCRIPTION OF SYMBOLS 1... Support stand, 2... Measured object, 3... Displacement detector, 4... Support mechanism, 1θ... Taper bin, 11...
... Turntable, 16... Drive motor, 18...
・Rotary encoder/, 19... Vacuum tube, 51
...Encoder, 53...A-D converter, 54...
・Memory unit, 55...Data analysis calculation unit, 551...
・CPU. 56...Display determination section.

Claims (1)

[Claims] An angle pulse generating means that generates an angle pulse at every predetermined rotation angle according to the rotation of 3 degrees of the object to be measured placed on the rotary table, and vacuum suction for the object to be measured on the rotary table. a displacement detector that contacts the surface of the object to be measured to detect displacement of the surface; a support mechanism that supports the displacement detector and brings it into contact with a predetermined position on the surface of the object to be measured; a memory unit that stores a surface displacement detection signal of the displacement detector in a time element using the angle pulse generated by the angle pulse generating means;
An error correction means for obtaining a ridge shape signal on the surface of the object to be measured by removing the error from the data in the memory section, and Fourier transform of the signal obtained by the error correction means to calculate the surface displacement with respect to frequency. and a display determination unit that displays the ridge shape signal based on an external command, or the spectrum and predetermined standard curve data for standard checking. A device for measuring surface ridges on objects.