JP2004198307A - Ultrasonic system and method for measuring thickness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively and surely carry out a thickness measurement without having adverse influence on an object to be measured. <P>SOLUTION: When carrying out measuring the thickness of a lens 15 in such a way that arrival time intervals between reflected waves being ultrasonic waves generated from an ultrasonic sensor 40, one of which arrives from the surface of the lens 15 and the other of which arrives from the rear face of the lens 15, are observed, and the distance between the surface and the rear face is calculated from the arrival time intervals, states of the reflected ultrasonic waves arriving thereat are monitored. When such a judgement that the lens 15 is placed at a position where above measurement can be carried out, is made based on monitored results, the measurement is carried out in this positional condition. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a technique for measuring the thickness of an object using ultrasonic waves.
[0002]
[Prior art]
The technique disclosed in Patent Document 1 will be described with reference to FIG.
In FIG. 5, an ultrasonic-transparent elastic body 104 is arranged on the surface of the ultrasonic probe 103 held by the handling device 101 via the pressure adjusting means 105 on the side of the object to be measured 102, and the pressure is adjusted. The ultrasonic probe 103 is pressed against the measured object 102 via the elastic body 104 by the means 105. In this case, the ultrasonic probe 103 is placed in contact with the measurement point of the object to be measured 102 via the elastic body 104 while maintaining the vertical state, and the pressing of the elastic body 104 The degree of elastic deformation is kept constant.
[0003]
In this state, the ultrasonic waves m emitted from the ultrasonic probe 103 are made to enter the object 102 through the elastic body 104 from a direction perpendicular to the surface of the object 102. This ultrasonic wave m is reflected on the bottom surface of the device under test 102, travels again in a direction perpendicular to the surface of the device under test 102, and returns to the ultrasonic probe 103 through the elastic body 104. At this time, thickness information of the measured object 102 is obtained from a time difference between detection timings of the ultrasonic waves returned from the ultrasonic probe 103 from the front surface and the back surface of the measured object 102 and the like.
[0004]
Patent Literature 1 discloses a technique for automatically measuring the thickness of the DUT 102 as described above.
[0005]
[Patent Document 1]
JP 2002-233952 A
[Problems to be solved by the invention]
In the production of industrial products in recent years, small-volume, multi-product production has increased, and the shape and thickness of the object to be measured vary widely, so that the pressing position (height) of the elastic body 104 is Often different. Under this situation, the automatic measurement of the thickness by the technique disclosed in the above-mentioned Patent Document 1 cannot determine whether or not the elastic body 104 has contacted the object to be measured 102 without fail. It is necessary to push the test object 102 into the object 102 more than necessary. For this reason, the measurement efficiency of the automatic measurement is reduced, and in addition, the object to be measured 102 may be deformed by pressing, and the measurement accuracy is deteriorated and the object to be measured 102 is damaged. Was.
[0007]
In view of the above problems, it is an object of the present invention to efficiently and reliably measure the thickness without adversely affecting the object to be measured.
[0008]
[Means for Solving the Problems]
The present invention performs observation of the difference in arrival time between the reflected wave of the emitted ultrasonic wave and that arriving from the front surface of the measured object and that arriving from the back surface of the measured object, An apparatus or method for measuring the thickness of the object to be measured by calculating the distance between the front surface and the back surface from the difference in the arrival time is assumed.
[0009]
In the ultrasonic thickness measuring apparatus according to one aspect of the present invention, a monitoring unit that monitors a state of arrival of a reflected wave of an ultrasonic wave and an object to be measured are located at a position where the above-described measurement can be performed. The above-described problem is solved by including a control unit that performs control for starting the measurement at the position when the determination that the measurement has been performed is made based on the result of the monitoring.
[0010]
According to the above configuration, the measurement of the object to be measured is performed at that position when it is determined that the object to be measured is located at a position where the thickness measurement can be performed based on the result of monitoring by the monitoring unit. By moving the measured object from the outside of the measurable range of the thickness measurement in a direction approaching the measurable range, the thickness of the measured object can be measured near the boundary of the measurable range.
[0011]
In addition, since it is possible to prevent a force that moves the object from its position to the inside of the measurable range from being applied to the object, the shape and thickness of the object vary. Even if it does, the deterioration of measurement accuracy and damage to the object to be measured due to this force can be suppressed, and the measurement efficiency can be improved by eliminating unnecessary movement of the object to be measured to the inside of the measurable range. Can be improved.
[0012]
Further, in the ultrasonic thickness measurement method which is another aspect of the present invention, the state of arrival of the reflected wave of the ultrasonic wave is monitored, and the object to be measured is located at a position where the above-described measurement can be performed. Is determined at the position when the determination is made based on the result of the monitoring.
[0013]
By doing so, the same operation and effect as those of the above-described ultrasonic thickness measuring apparatus according to the present invention can be obtained, and the above-mentioned problem can be solved.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, a case where the present invention is implemented in measuring the thickness of the optical lens will be described.
FIG. 1 shows the overall configuration of an apparatus for implementing the present invention.
[0015]
In FIG. 1, the handling device 10 is arbitrarily controlled to move vertically by a driving unit 20. The arithmetic unit 30 controls the transmission and reception of the ultrasonic wave by the ultrasonic sensor 40 and receives the ultrasonic wave emitted from the ultrasonic sensor 40 based on the time required until the ultrasonic wave is reflected and received by the ultrasonic sensor 40. The thickness of the measured object is calculated. The control unit 50 controls the driving unit 20 and the calculation unit 30.
[Example 1]
Next, FIG. 2 will be described. FIG. 2 shows a first example of a detailed configuration around the handling device 10 and the ultrasonic sensor 40 in FIG.
[0016]
The handling device 10 is configured by inserting a piston 13 into a cylinder 11. FIG. 2A shows a state in which the piston 13 is pushed downward from the cylinder 11 by the elastic force of the spring 12 which is an elastic body. A lens holding portion 14 is provided at the tip of the piston 13, and the lens 15 can be held by a method such as clamping, sticking, or suction.
[0017]
An ultrasonic sensor 40 is disposed below the handling device 10 so as to be immersed or in close contact with the ultrasonic wave propagation member 16. In addition, as the ultrasonic wave propagation member 16, for example, a liquid such as water, oil, or a grinding fluid may be used, or a solid such as silicon, polycarbonate, vinyl chloride, or acryl may be used.
[0018]
Hereinafter, a procedure for measuring the thickness of the lens 15 using the apparatus having the configuration shown in FIGS. 1 and 2 will be described.
First, the control unit 50 gives an instruction to the drive unit 20 to move the handling device 10 downward in FIG. 2, and lowers the lens 15 toward the ultrasonic wave propagation member 16 as shown in FIG. To go. In this state, when the control unit 50 gives an instruction to the calculation unit 30 to generate an ultrasonic wave from the ultrasonic sensor 40, the transmission wave e, which is the ultrasonic wave, propagates through the ultrasonic wave propagation member 16 and the ultrasonic wave propagation member The light is reflected at the interface 16 and becomes an interface reflected wave f, and returns to the ultrasonic sensor 40. FIG. 3A shows a measurement signal of the ultrasonic sensor 40 confirmed by the calculation unit 42 at this time.
[0019]
In FIG. 3A, the transmission waveform 41 indicates the time when the transmission wave e is emitted, and the interface reflection waveform 42 indicates the time when the interface reflection wave f arrives. Note that the horizontal axis in FIG. 3 indicates the passage of time.
Thereafter, when the downward movement of the handling device 10 is continued, the lens 15 comes into contact with the ultrasonic wave propagation member 16 and then enters as shown in FIG. 2B. FIG. 3B shows a measurement signal from the ultrasonic sensor 40 confirmed by the calculation unit 42 at this time.
[0020]
In FIG. 3B, what appears next to the transmission waveform 41 is a lens surface reflection waveform 43 which is a detection result of the ultrasonic wave reflected on the surface of the lens 15 (the lower surface in FIG. 2). After that, the propagation time of the traveling wave i of the ultrasonic wave propagating through the lens 15 from the front surface to the back surface of the lens 15 is changed to the lens 15 of the back surface reflected wave k which is the reflected wave of the traveling wave i at the back surface of the lens 15. The lens back surface reflection waveform 44 appears at a position corresponding to the time obtained by adding the propagation time from the back surface to the front surface.
[0021]
In FIG. 3B, the time interval between the lens surface reflection waveform 43 and the lens back surface reflection waveform 44 does not change depending on the position of the lens 15, but the positional relationship between these waveforms and the transmission waveform 41 is determined by the handling device 10 shown in FIG. It changes in conjunction with the vertical movement of. This is because the surface reflection waveform 43, which is a reflection wave of the traveling wave g on the surface of the lens 15, corresponds to the propagation time of the transmission wave g propagating in the ultrasonic wave propagation member 16 to the surface of the lens 15. This is because the position of the lens 15 moves in the ultrasonic wave propagation member 16 while the time obtained by adding the propagation time of the wave h to the ultrasonic sensor 40 is shown.
[0022]
By the way, when the ultrasonic wave propagation member 16 is solid, the lens 15 is attached to the ultrasonic wave propagation member 16 by a cylinder mechanism configured by the cylinder 11, the piston 13 and the spring 12 provided in the handling device 10. Since the lens 15 is held down and the lens 15 does not enter the ultrasonic wave propagation member 16, the vertical movement of the handling device 10 and the movement of the waveform in the measurement signal by the ultrasonic sensor 40 are not linked. However, even in this state, the measurement signal detected by the ultrasonic sensor 40 includes the lens surface reflection waveform 43 and the lens back surface reflection waveform 44 as shown in FIG. 3B.
[0023]
To summarize the above, based on information obtained from the drive unit 20 and the arithmetic unit 30, the vertical movement of the handling device 10 and the lens surface reflection waveform 43 or the lens back surface represented in the measurement signal detected by the ultrasonic sensor 40. Detecting that the movement of the reflection waveform 44 is interlocked, or that the lens surface reflection waveform 43 and the lens back surface reflection waveform 44 appear in the measurement signal detected by the ultrasonic sensor 40 in place of the interface reflection waveform 42 Accordingly, the control unit 50 can know that the lens 15 has come into contact with the ultrasonic wave propagation member, that is, that the thickness of the lens 15 can be measured.
[0024]
Thereafter, when it is determined that the thickness of the lens 15 can be measured, the control unit 50 gives an instruction to the calculation unit 30 and, for example, a method similar to that disclosed in the above-mentioned Patent Document 1 To measure the thickness of the lens 15.
By doing so, it is possible to detect that the lens 15 has come into contact with the ultrasonic wave propagation member 16, so that it is not necessary to lower the handling device 10 more than necessary, and the ultrasonic wave propagation member 16 In this case, the contact pressure can be suppressed as much as possible. As a result, it is possible to prevent the lens 15 from being damaged due to the thickness measurement, and it is also possible to immediately detect a state where the thickness measurement becomes possible even when the lens 15 having a random thickness is inserted, for example. Because it is possible, it can respond quickly to lenses of various thicknesses.
[Example 2]
Next, FIG. 4 will be described. This figure shows a second example of the detailed configuration around the handling device 10 and the ultrasonic sensor 40 in FIG.
[0025]
4, the configuration of the handling device 10 is the same as that shown in FIG. 2, but the holding portion between the ultrasonic wave propagation member 16 and the ultrasonic sensor 40 is different from that shown in FIG.
As shown in FIG. 4A, the ultrasonic sensor 40 is inserted into the sensor holding cylinder 17. A hole space having an arbitrary size is provided in the ultrasonic wave propagation direction of the ultrasonic sensor 40 in the sensor holding cylinder 17, and the ultrasonic wave propagation member 16 is held in the hole space. The ultrasonic wave propagation member 16 is configured to be flush with the opening of the sensor holding cylinder 17 or protrude from the opening. By employing this configuration, the amount of use of the ultrasonic wave propagation member 16 can be made smaller than in the configuration example shown in FIG.
[0026]
Hereinafter, a procedure for measuring the thickness of the lens 15 using the apparatus having the configuration shown in FIGS. 1 and 4 will be described.
First, the control unit 50 gives an instruction to the driving unit 20 to move the handling device 40 downward in FIG. 4, and lowers the lens 15 toward the ultrasonic wave propagation member 16 as shown in FIG. To go. At this time, the measurement signal by the ultrasonic sensor 40 confirmed by the calculation unit 42 is the same as that shown in FIG.
[0027]
Thereafter, when the downward movement of the handling device 10 is continued, the lens 15 comes into contact with the sensor holding cylinder 17 (the ultrasonic wave propagation member 16) as shown in FIG. 4B. The waveform observed by the ultrasonic sensor 40 in this state is as shown in FIG.
[0028]
Thereafter, even if the handling device 10 is further lowered from this state, as shown in FIG. 4C, the piston 13 is drawn into the cylinder 11 by the cylinder configuration constituted by the cylinder 11, the piston 13 and the spring 12. Therefore, the lens 15 is only weakly attached to the sensor holding cylinder 17 by the elastic force of the spring 12 and the own weight of the spring 12, the piston 13, and the lens holding unit 14.
[0029]
Hereinafter, in the same manner as in the first embodiment, based on the information obtained from the driving unit 20 and the arithmetic unit 30, the ultrasonic wave sensor 40 generates the lens surface reflection waveform 43 and the lens back surface reflection waveform 44 instead of the interface reflection waveform 42. By confirming the appearance of the detected measurement signal, the control unit 50 can know that the lens 15 has come into contact with the ultrasonic wave propagation member 16, that is, the thickness of the lens 15 can be measured. Therefore, after this detection, the control unit 50 gives an instruction to the calculation unit 30 to cause the thickness measurement of the lens 15 to be performed by, for example, the same method as that disclosed in Patent Document 1 described above.
[0030]
By doing as described above, the pressing load on the lens 15 can be suppressed to a small value, and it is possible to know that the lens 15 is positioned so as to be able to reliably measure. Further, since the thickness of the lens 15 can be measured by using a very small or minute ultrasonic wave propagation member 16, it is advantageous in terms of cost and securing a space required for the measurement.
[0031]
In addition, the present invention is not limited to the above-described embodiment, and various improvements and modifications can be made without departing from the gist of the present invention.
[0032]
【The invention's effect】
As described in detail above, the present invention provides a method of arriving between reflected waves of an emitted ultrasonic wave that arrive from a surface of an object to be measured and those that arrive from a back surface of the object to be measured. When the time difference is observed and the thickness of the object is measured by calculating the distance between the front surface and the back surface from the arrival time difference, the arrival of the reflected wave of the ultrasonic wave Is monitored, and when it is determined based on the result of the monitoring that the object to be measured is located at a position where the above-described measurement can be performed, the measurement is performed at the position.
[0033]
By doing so, there is an effect that the thickness can be measured efficiently and reliably without adversely affecting the object to be measured.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an apparatus for implementing the present invention.
FIG. 2 is a diagram showing a first example of a detailed configuration around a handling device and an ultrasonic sensor in FIG. 1;
FIG. 3 is a diagram illustrating an example of a measurement signal detected by an ultrasonic sensor.
FIG. 4 is a diagram illustrating a second example of a detailed configuration around the handling device and the ultrasonic sensor in FIG. 1;
FIG. 5 is a diagram illustrating a conventional technique.
[Explanation of symbols]
Reference Signs List 10 Handling device 11 Cylinder 12 Spring 13 Piston 14 Lens holding unit 15 Lens 16 Ultrasonic wave propagation member 20 Drive unit 30 Operation unit 40 Ultrasonic sensor 41 Transmission waveform 42 Interface reflection waveform 43 Lens surface reflection waveform 44 Lens back surface reflection waveform 50 Control unit Reference Signs List 101 Handling device 102 Object to be measured 103 Ultrasonic probe 104 Elastic body 105 Press adjusting means

Claims (2)

Of the reflected waves of the emitted ultrasonic waves, the difference in the arrival time between the one arriving from the front surface of the object to be measured and the one arriving from the back surface of the object to be measured is observed, and the time of arrival is measured. In an ultrasonic thickness measurement device that measures the thickness of the object to be measured by calculating the distance between the front surface and the back surface from the difference,
Monitoring means for monitoring the state of arrival of the reflected wave for the ultrasonic wave,
A control unit that controls the measurement to be performed at the position when the determination that the object is located at a position where the measurement can be performed is performed based on the result of the monitoring.
An ultrasonic thickness measuring device, comprising: Of the reflected waves of the emitted ultrasonic waves, the difference in the arrival time between the one arriving from the front surface of the object to be measured and the one arriving from the back surface of the object to be measured is observed, and the time of arrival is measured. When measuring the thickness of the object to be measured by calculating the distance between the front surface and the back surface from the difference,
Monitor the state of arrival of the reflected wave of the ultrasonic wave,
Performing the measurement at the position when the determination that the DUT is located at a position where the measurement can be performed is performed based on the result of the monitoring,
An ultrasonic thickness measuring method, characterized in that:

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