JP2520200B2 - High speed displacement measuring device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high speed displacement measuring device for measuring the displacement of an object (object to be measured) vibrating at a high speed.

[0002]

2. Description of the Related Art The development of electronic technology in recent years has been remarkable, and the technology is used in all fields. The use of electronic technology has enabled measurement that was once impossible. One of them is a method of measuring the displacement of an object using a semiconductor position detecting element (hereinafter referred to as PSD).
This is a method of measuring using a position sensor. PS
D has a structure as shown in FIG. 6 in a simple manner, and has a property that the photocurrent output of the output terminal varies depending on the position of incident light. The position sensor measures the displacement of the object based on the principle of triangulation utilizing the difference in the photocurrent output. 2 for PSD as shown in FIG.
FIG. 8 shows an example of a position sensor configured by using the PSD that enables the dimensional position detection, and FIG. 9 shows an output example of the two-dimensional position detection of the position sensor of FIG. An example of a basic displacement measuring system using a position sensor (hereinafter referred to as a position sensor system) is shown in FIG. In this position sensor system, the light from the light source 1010 is collected by the light projecting lens 140 at the spot position 1020, and the scattered light is collected on the light receiving surface of the PSD 112 of the position sensor 110. PSD 112 and position calculation circuit 1
The position of the light receiving surface of the PSD 112 is calculated at 13, and the displacement of the DUT 100 is measured based on the position of the light receiving surface of the PSD 112. The measurement accuracy of this position sensor system is high,
For example, when the PSD of the position sensor has a visual field of 10 mm, the resolution is about 2 or 3 micrometers.

By measuring displacement using such a position sensor, remote non-contact, high accuracy (positional resolution of about 1/5000), multipoint simultaneous measurement, three-dimensional position measurement, etc. have never been possible before. It has become possible to measure the displacement of objects, and it has been applied in a wide range of fields including impact / deformation tests, vibration / displacement measurement, gait analysis, sports / work posture analysis, and so on.

[0004]

Although the position sensor system has come to be used in various measurement fields and its advantages have been understood, in the position sensor system shown in FIG. 10, the response speed of the PSD is increased. From
The response speed of the system is limited to about several hundred microseconds. In impact / deformation tests and vibration / deviation measurement, there is a strong demand for the position sensor system to be able to accurately measure the displacement of an object (measurement object) that exceeds the response speed. For example, piezoelectric elements such as ceramic vibrators are considered for wide applications such as microactuators and engine valves because of their high speed and controllability, but the displacement of the piezoelectric elements is several micrometers, and the response speed is several microseconds or less. Therefore, it is impossible to directly measure the vibration and displacement of the piezoelectric element. As described above, in the position sensor system described above, there is a limit to its application due to the response speed of PSD.

SUMMARY OF THE INVENTION In view of the above points, it is an object of the present invention to provide a high speed displacement measuring device capable of accurately measuring the displacement of an object vibrating at a high speed exceeding the response speed of PSD.

[0006]

A high-speed displacement measuring device according to a first aspect of the present invention includes a drive output generator that generates a light source drive output that is synchronized with the vibration of an object to be measured and is out of phase with the vibration, and a light source. Equipped with a pulse light source for spot-irradiating the measured object with pulsed light whose pulse width is sufficiently shorter than the vibration cycle of the measured object according to the drive output, and a position detector for detecting reflected light from the measured object. A drive output generator, a vibration drive circuit for generating a vibration drive output for vibrating the object to be measured, a phase shift means for changing the phase of the vibration drive output, and a phase shift output from the phase shift means. And a light source driving circuit for generating a light source driving output. The high-speed displacement measuring device according to claim 2 is a drive output generator that generates a light source drive output that is synchronized with the vibration of the measured object and is out of phase with the vibration, and the measured object according to the light source drive output. The drive output generator is equipped with a pulse light source that irradiates the DUT with a pulsed light whose pulse width is sufficiently shorter than the vibration period, and a position detector that detects the reflected light from the DUT. Vibration detection means for detecting the vibration of an object, phase shift means for changing the phase of the detection output from this vibration detection means, and a light source drive circuit for generating a light source drive output based on the phase shift output from this phase shift means. It is characterized in that it is configured to include. A high-speed displacement measuring apparatus according to claim 3, wherein a drive output generator that generates a light source drive output that is synchronized with the vibration of the object to be measured and is out of phase with the vibration, and a light source drive output provided on the object to be measured. The pulse output source generates a pulsed light whose pulse width is sufficiently shorter than the vibration cycle of the DUT, and a position detector that detects the pulsed light.The drive output generator vibrates the DUT. A vibration driving circuit for generating a vibration driving output, a phase shifting means for changing the phase of the vibration driving output, and a light source driving circuit for generating a light source driving output based on the phase shifting output from the phase shifting means. It is characterized by being composed of. A high-speed displacement measuring apparatus according to claim 4, wherein a drive output generator that generates a light source drive output that is synchronized with the vibration of the object to be measured and is out of phase with the vibration, and a light source drive output provided on the object to be measured. According to, a pulse light source that generates a pulsed light having a pulse width sufficiently shorter than the period of vibration of the measured object, and a position detector that detects the pulsed light, the drive output generator,
Vibration detecting means for detecting the vibration of the object to be measured, and phase shifting means for changing the phase of the detection output from the vibration detecting means,
And a light source drive circuit for generating a light source drive output based on the phase shift output from the phase shift means. A high-velocity displacement measuring apparatus according to a fifth aspect is the high-velocity displacement measuring apparatus according to any one of the first to fourth aspects, further comprising means for moving an object to be measured parallel to a surface intersecting the optical axis of the pulsed light. It is characterized by

[0007]

[0008]

[0009]

The driving output generator generates a light source driving output that is synchronized with the vibration of the object to be measured and is out of phase with the vibration, and the pulse light source emits pulsed light in accordance with the light source driving output, and the pulsed light is received. The reflected or scattered light when the measurement object is spot-irradiated, or the pulsed light from the pulsed light source provided on the measurement object reaches the position detector. Here, since the pulsed light source synchronizes with the vibration of the object to be measured and emits light whose phase is shifted with respect to the vibration, reflection at a position deviated from the center of vibration by an amount corresponding to the phase shift, It is scattered or luminescent. Therefore, it is equivalent to reaching from a stationary position. The position detector detects the spot-irradiated position from the reflected light, and the displacement of the measured object is measured from the difference in the detected positions.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. The same or equivalent parts as those in the above-mentioned conventional example are designated by the same reference numerals, and the description thereof will be simplified or omitted. FIG. 1 shows an example of a high speed displacement measuring device which is a first embodiment of the present invention.

The high-speed displacement measuring device shown in FIG. 1 is for measuring the displacement by vibrating an object to be measured by an electric means. This apparatus vibrates the DUT 100 and generates a light source driving output which is synchronized with the vibration and generates a phase-shifted light source, and a pulsed light to the DUT 100 according to the light source driving output. Pulse light source 1
20 and a position sensor 110 as a position detector that detects reflected light from the object 100 to be measured.
Reference numeral 140 is a lens for converging the pulsed light, and reference numeral 101 is a position (hereinafter referred to as a spot position) on the DUT 100 where the pulsed light from the pulsed light source 120 is spot-irradiated.

The device under test 100 is made of a ceramic oscillator and vibrates at high speed by the output from the drive output generator 130. The drive output generator 130 is the device under test 100.
And a phase shift circuit 132 that changes the phase of the vibration output from the vibration drive circuit 131 according to the phase shift signal input 134, and the phase shift circuit 132.
2 includes a light source drive circuit 133 that drives a pulse light source from the phase shift output from the pulse shift source, and generates a light source drive output whose phase is shifted with respect to the vibration of the DUT 100 as shown in FIG. The light emission timing of 120 is controlled. The pulse light source 120 is composed of a laser diode, a light emitting diode, or the like, and generates pulsed light (pulse width microseconds to nanoseconds) having a pulse width sufficiently shorter than the vibration cycle of the DUT 100. .

Next, the operation of this apparatus will be described.

Vibration drive circuit 13 of drive output generator 130
1, the device under test 100 vibrates at a high speed at a predetermined cycle. The output of the vibration driving circuit 131 for driving the device under test 100 is shifted in phase by an amount corresponding to the phase shift signal input 134 in the phase shift circuit 132, and based on that, the light source for controlling the timing of light emission of the pulse light source 120. Generate drive output. This drive output causes the pulsed light source 120 to emit light. The relationship between the vibration of the DUT 100 and the light emission timing of the pulse light source 120 is as shown in FIG.
When the amount of phase shift at 32 is θ, the pulsed light source 120 emits light when the DUT 100 comes from the center of its vibration to d. The pulsed light from the pulsed light source 120 is condensed at the spot position 101, which is the measurement point, and the measured object 1
It is scattered at 00. The spot position 101 is a fixed position separated from the center of vibration of the DUT 100 by a predetermined distance according to the timing of light emission of the pulse light source 120. The scattered pulsed light is transmitted to the position sensor 110.
Are collected on the light receiving surface of PSD 112. The position of the light receiving surface of the PSD 112 is calculated by the PSD 112 and the position calculation circuit 113, and based on this, the spot position 1 is calculated by the principle of triangulation.
01 is obtained, and the displacement of the DUT 100 is measured.

Although the response speed of the PSD 112 of the position sensor 110 is not good, the spot position 101
Is at a fixed position due to the amount of phase shift of the phase shift circuit 132, which is the same as measuring a stationary object. Therefore, the DUT 100 that vibrates at high speed regardless of the response speed of the PSD 112. The displacement of the vibration is measured. By changing the amount of phase shift of the phase shift circuit 132 by θ, the spot position 101 changes, and the maximum value of the displacement of vibration, the vibration waveform of the measured object, and the like can be obtained.

Next, other embodiments will be described.

In the embodiment of the second embodiment shown in FIG. 3, instead of the vibration drive circuit 131, a drive means 350 for driving the DUT 300 is provided outside the apparatus, and this drive means 35 is provided.
0 causes the device under test 300 to vibrate. This high-speed displacement measuring device is characterized in that a vibration detection circuit 331 for detecting the vibration of the DUT 300 is provided, and the detection output of the vibration detection circuit 331 is output to the phase shift circuit 132. . The operation of this device is the same as that of the drive output generator of the device of the first embodiment described above.
This is equivalent to the detection output of the vibration detection circuit 331 instead of the vibration output of. Since the detection output of the vibration detection circuit 331, that is, the vibration waveform of the measured object is output to the phase shift circuit 132, the relationship between the vibration of the measured object 100 and the light emission timing of the pulse light source 120 is described above. Similar to the first embodiment described above, the result is as shown in FIG. Therefore, the operation principle of this device such as the spot position detection in the position sensor 110 is the same. In this device,
As shown in the figure, high-speed vibration analysis is possible even when the response frequency of the vibration detection circuit is slow.

The high speed displacement measuring apparatus of the third embodiment shown in FIG. 4 is characterized in that the pulse light source 420 is provided on the vibrating object to be measured. This is because the element used for the pulse light source 120 is extremely small. Compared with the device of the first embodiment described above, there is an advantage that a pulsed light directly enters the position sensor 110 without being scattered on the object to be measured, so that a light source that is strong against disturbance and relatively weak can be used. . In this figure, the vibration sensor 131a is included in the vibration detection circuit 331, but is shown separately in the drawing. The embodiment of FIG. 4 has the same configuration as that of the second embodiment, but similarly to the first embodiment, a vibration drive circuit for vibrating the object to be measured is provided instead of the vibration detection circuit 331. Is also good. The pulse light source may be one introduced from the outside by an optical fiber or the like.

In the high speed displacement measuring apparatus of the fourth embodiment shown in FIG. 5, the object 110 to be measured is placed on the XY stage 510, and the spot position 101 which is the measurement point is the object 110 to be measured.
The feature is that it can move on the surface of. An object that oscillates at high speed may be accompanied by a secondary resonance on its surface, and by moving the spot position 101 on the surface of the DUT 100, a one- or two-dimensional vibration pattern of the secondary resonance or the like. Is to measure. XY stage 5
By interlocking the movement of 10 and the spot position detection of the position sensor 110, a one- or two-dimensional vibration pattern can be easily obtained. Also in this case, the pulsed light source may be provided on the object to be measured as in the second embodiment. Next, a modified example of the present invention will be described.

As for the object to be measured, an example in which a ceramic vibrator is used has been shown. However, not only such a piezoelectric element, but any object that vibrates due to the principle of this device can be an object to be measured. The vibration drive circuit does not have to be inside the device, and may be replaced with a device that vibrates and drives the object to be measured outside the device. In this case, the device replaces the vibration drive circuit. Further, the vibration waveform of the object to be measured is not limited to a sine wave, but various responses can be measured by measuring a pulse wave such as a square wave or a ramp wave.

The phase shift circuit may be any one that can control the pulse light source at the timing shown in FIG.
It can be configured using elements such as a delay line, a shift register, and a comparator. Alternatively, two oscillators may be used, one for driving the light source and the other for driving the vibration, and the oscillation frequencies of the two oscillators may be slightly shifted so that the phase continuously changes depending on the beat frequency. . The position detector using a PSD such as a position sensor is highly accurate, but is not limited to this when the accuracy is not so high, and a solid state element such as a self-scanning image sensor may be used. When a solid-state element is used, it is advantageous to reduce the size and weight, but when it is not necessary to use such a solid-state element, other image pickup elements and pickup tubes can be used. Further, as shown in FIG. 12, a function for changing the obtained vibration waveform into an analog or digital signal by the phase shift change of the phase shift circuit and displaying it on the monitor is also included.

[0022]

As described above, according to the present invention, it is equivalent to measuring an object in which the spot position of the object to be measured is stationary, and a position detector having a poor response speed is used to vibrate at high speed. The displacement of a moving object can be measured with extremely high accuracy.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a diagram showing the relationship between the vibration of the object to be measured and the emission timing of the pulsed light source.

FIG. 3 is a configuration diagram of a second embodiment.

FIG. 4 is a configuration diagram of a third embodiment.

FIG. 5 is an explanatory diagram of a fourth embodiment.

FIG. 6 is a structural diagram of PSD.

FIG. 7 is a structural diagram of a two-dimensional PSD.

FIG. 8 is a diagram showing a configuration example of a position sensor.

FIG. 9 is a diagram showing an output example of a position sensor.

FIG. 10 is a configuration diagram of a conventional example.

FIG. 11 is a diagram showing the relationship between the vibration of the object to be measured and the emission timing of the pulse light source.

FIG. 12: Example of adding function to display on monitor

[Explanation of symbols]

 100 ... Object to be measured 110 ... Position sensor 120 ... Pulse light source 112 ... PSD 130 ... Drive output generator 131 ... Vibration drive circuit 132 ... Phase shift circuit 133 ... Light source drive circuit 331 ... Vibration detection circuit

Claims (5)

(57) [Claims] 1. Synchronizing with the vibration of an object to be measured,
A drive output generator that generates a light source drive output that is out of phase;
Depending on the light source drive output, the vibration cycle of the DUT may be changed.
A pulsed light with a sufficiently short pulse width to the DUT.
Pulsed light source for pot irradiation and reflection from the DUT
A position detector for detecting light, wherein the drive output generator vibrates the DUT.
A vibration driving circuit for generating a vibration driving output of the
Phase shift means for changing the phase of drive output, and this phase shift means
Light that generates the light source drive output based on the phase shift output from
A high-speed displacement measuring device comprising a source drive circuit . 2. The vibration of an object to be measured is synchronized with the vibration of the object to be measured.
A drive output generator that generates a light source drive output that is out of phase;
Depending on the light source drive output, the vibration cycle of the DUT may be changed.
A pulsed light with a sufficiently short pulse width to the DUT.
Pulsed light source for pot irradiation and reflection from the DUT
A position detector for detecting light, wherein the drive output generator detects vibration of the measured object.
The vibration detection means and the position of the detection output from this vibration detection means
Phase shift means for changing the phase and phase shift output from this phase shift means
A light source drive circuit that generates the light source drive output based on force,
A high-velocity displacement measuring device comprising: 3. The vibration of an object to be measured is synchronized with the vibration of the object to be measured.
A drive output generator that generates a light source drive output that is out of phase;
Depending on the light source drive output provided on the DUT
The pulse width is sufficiently shorter than the period of vibration of the DUT.
A pulse light source that generates pulsed light and detects the pulsed light
And a drive position generator for vibrating the object to be measured.
A vibration driving circuit for generating a vibration driving output of the
Phase shift means for changing the phase of drive output, and this phase shift means
Light that generates the light source drive output based on the phase shift output from
A high-speed displacement measuring device comprising a source drive circuit . 4. The vibration is synchronized with the vibration of the object to be measured.
A drive output generator that generates a light source drive output that is out of phase;
Depending on the light source drive output provided on the DUT
The pulse width is sufficiently shorter than the period of vibration of the DUT.
A pulse light source that generates pulsed light and detects the pulsed light
And a position detector that operates to detect the vibration of the measured object.
The vibration detection means and the position of the detection output from this vibration detection means
Phase shift means for changing the phase and phase shift output from this phase shift means
A light source drive circuit that generates the light source drive output based on force,
A high-velocity displacement measuring device comprising: 5. characterized in that the Ru further comprising a means for moving parallel to the object to be measured on the surface that intersects the optical axis of the pulsed light
The high speed displacement measuring device according to any one of claims 1 to 4 .