JPS59168304A - Surface-shape measuring device - Google Patents

Abstract

PURPOSE:To measure the shape of a surface highly accurately without effects of disturbance such as vibration and noises, by additionally using an auxiliary sensor, which detects only background noises caused by the disturbance. CONSTITUTION:The tip of the probe of a sensor 2 is contacted and fixed to the surface of a sample 1 and detects only background noises. The vicinity of the fixed position of said sensor 2 is scanned by the tip of the probe of a sensor 3, and the surface roughness corresponding to the shape of the surface and the background noises are detected. The detected outputs from the sensors 2 and 3 are fed to a signal processing circuit 6 through amplifiers 4 and 5, and subtraction and the like are performed in the circuit 6. Thus the measurement of the surface shape can be performed highly accurately without the effects of disturbance such as vibration and noises.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a measuring device suitable for measuring the surface shape of a sample, such as surface roughness, waviness, and outline of the sample.

Conventionally, a device for measuring the surface roughness of a sample such as a magnetic tape is equipped with a sensor having a stylus, and the sensor is moved by bringing the tip of the stylus into contact with the surface of the magnetic tape. A measuring device is known in which a data signal representing the unevenness of a sample surface is obtained from the sensor.

By the way, according to the current Kaga7a+ device, the sensor and sample are affected by disturbances such as vibration and noise, and the detection output signal from the sensor contains data representing the surface roughness of the sample. Noise due to disturbance (hereinafter referred to as background noise) is mixed into the signal, and measurement accuracy is significantly reduced.

Therefore, in order to prevent the measurement accuracy from decreasing due to such disturbances, when performing high-precision measurements in an environment where disturbances occur, the sample should be placed on a vibration isolation table or in a soundproof case.
I was doing 11. However, when measuring the surface roughness of a sample with an ultra-mirror finish, even if you use a stand or a soundproof case, it may not be sufficient in an environment with relatively large vibrations and noise, such as in a factory. Unable to obtain measurement accuracy.

In addition, in particular, it is often necessary to use a lifting platform to measure the surface condition of a very large sample within the factory where the sample was manufactured, which causes large external disturbances and requires the use of a vibration-isolating platform or sound-proof case. There are many cases where it is not possible to use the method, which has the disadvantage of making measurement impossible.

SUMMARY OF THE INVENTION An object of the present invention is to provide a surface shape measuring device that eliminates the drawbacks of the prior art described above and enables highly accurate measurement without being affected by disturbances such as vibration and noise.

To achieve this objective, the present invention provides an auxiliary sensor that detects only background noise due to external aging,
The feature is that ground noise is canceled out from the detection output signal of the sensor that sweeps the sample by the detection output signal of the auxiliary sensor, and a data signal representing the surface shape of the sample is obtained.

Embodiments of the present invention will be described below with reference to the drawings.

The figure is a configuration diagram showing an embodiment of the surface shape measuring device according to the present invention, in which 1 is a sample, 2 and 3 are sensors, 4.5 is an amplifier circuit, 6 is a signal processing circuit, and 7 is an output terminal. .

This embodiment will be explained using a stylus type surface roughness meter as an example.

In the figure, a sensor 2 is fixed with the tip of a stylus touching the surface of a stationary sample 1, and is an auxiliary sensor that detects only background noise. sensor 3
The tip of the stylus is brought into contact with the surface of the sample 1, is movable parallel to the surface of the sample 1, and generates a signal corresponding to the unevenness of the surface of the sample 1. These sensors 2 and 3 have the same characteristics and are arranged very close to each other.
Once the setting position is determined, the sensor 3 moves in the vicinity and sweeps the surface of the sample 1. When such a sweep is completed, the sample 1 is moved, the sensor 2 is set at a new position on the surface of the sample 1, and the vicinity thereof is again swept with the sensor 3. In this way, the sensor 3 sweeps the entire surface of the sample 1.

By the way, when the sample 1 and the sensors 2 and 3 vibrate due to a disturbance, the sensor 2 obtains only the bank ground noise caused by the disturbance as a detection output signal, and the sensor 3 obtains only the bank ground noise caused by the disturbance as a detection output signal. Because they are very close to each other, a detection output signal is obtained in which background noise similar to the background noise detected by the sensor 2 is mixed into the data signal representing the surface roughness of the sample 1.

The detection output signals from the sensors 2 and 3 are sent to amplifier circuits 4 and 3, respectively.
5 and are amplified so that the background noise levels of the respective detection output signals match, and are supplied to a signal processing circuit 6. The signal processing circuit 6 subtracts the output signal of the amplifier circuit 4 from the output signal of the amplifier circuit 5. As a result,
The background noise is canceled out from the detection output signal of the sensor 3, and the data signal from which the bank ground noise has been removed is obtained at the output terminal 7. This data signal is
The surface roughness of the sample 1 is measured by processing in the same manner as with a conventional measuring device.

Next, the results of measuring the surface roughness of a sample using this example will be shown in comparison with the results of measuring using other measuring devices.

As samples, we used two types of hard chrome-plated metal plates that were polished to a mirror finish with different precision using a grinder installed in the workshop, and these were designated as Sample A.

The sample was dropped.

Measurement samples A and B using Example (a) were polished to a mirror finish using a grinder, and then placed on the grinder as they were. The surface roughness of each was measured using a meter.

(b) Comparative Example 1 The surface roughness of each sample was measured using a conventional surface roughness meter under the same conditions as in (a) above.

(C) Comparative Example 2 Parts of Samples A and B were cut out and installed in a dedicated measurement room equipped with an anti-vibration table and a soundproof case, respectively, and the conventional The surface roughness of each sample was measured using a surface roughness meter.

Note that the conventional surface roughness meter is the standard correction d(1) device described above as the prior art.

From each roughness cross-sectional curve obtained by the above measurements, R
The a value was determined. The following table shows the Ra value for each measurement, sample, and sample.

As is clear from the above table, if a total of 6) 1[ was performed using the example, the same measurement results as Comparative Example 2 would be obtained. Comparative Example 2 is a measurement in a state where there is almost no disturbance, so if the example is used, even if the disturbance is large, results similar to measurements in an environment without disturbance can be obtained.

In addition, in the above embodiment, a stylus-type sensor was used as the sensor, or a sensor based on another principle such as an optical glove could be used, and it is possible to obtain the same effect. do not have.

Furthermore, in the above embodiment, the case of measuring surface roughness was explained, but it is clear that it can be similarly used to measure other surface shapes such as undulations and contours.
Further, a plurality of sensors for sweeping (sensor 3 in the figure) may be used.

As explained above, according to the present invention, it is possible to obtain a data signal representing the surface shape of a sample with a high S/N ratio by removing background noise caused by disturbance, and it is possible to obtain a data signal representing the surface shape of a sample with a high S/N ratio. Accordingly, it is possible to realize measurement with extremely high sieving accuracy, and it is possible to provide a surface shape measuring device with excellent functions by eliminating the drawbacks of the above-mentioned conventional techniques.

[Brief explanation of the drawing]

The figure is a configuration diagram showing an embodiment of the surface shape meter 6; 1j device according to the present invention. 1...Sample, 2,3...Sensor, 4,5
...Amplification circuit, 6...Signal processing circuit.

Claims (1)

[Claims] An aid for detecting background noise in a surface shape measuring device that is equipped with a sensor that is displaced relative to the sample, and that sweeps the sample with the sensor to obtain a data signal representing the surface shape of the sample. a sensor, and a signal processing circuit that is supplied with detection output signals from the sensor and the auxiliary sensor and subtracts the detection output signal from the auxiliary sensor from the detection output signal of the sensor,
A surface shape measuring device characterized in that the signal processing circuit is configured to cancel out the background noise mixed in the detection output signal from the sensor and obtain the data signal f:.