JPH08105735A - Quality evaluation apparatus of pearl - Google Patents

Abstract

PURPOSE: To obtain a quality evaluation apparatus by which a precise wound thickness is measured objectively and by which the reliability of an evaluation is enhanced by a method wherein ultrasonic waves are made to fall on a pearl, surface reflected waves are detected from their reflected waves, interface reflected waves at the interface between the nucleus and the wound part of the pearl are detected and the wound thickness of the pearl is computed on the basis of the time difference between the surface reflected waves and the interface reflected waves. CONSTITUTION: A pearl S is held by a pearl holding part 5, it is aligned with a part near a focus in which ultrasonic waves are converged, and it is arranged inside a water tank 6 together with the sound-wave transmitting and receiving face of an acoustic lens 4. Then, one-shot pulse waves at 25 to 100MHz from a transmitter 1 are applied to a transducer 3 via a circulator 2, they are wave-transmitted as spherical waves from the sound-wave transmitting and receiving face of the acoustic lens 4, and reflected waves from the pearl S are received so as to be converted into an electric signal. A signal extraction part 7 extracts, from the input electric signal, a signal which simultaneously contains the surface reflected waves and the interface reflected waves. The signal is displayed on a digital oscilloscope 8, and it is stored in a buffer memory 15. A CPU 17 reads out the waveform of reflected waves from the memory 15, and it computes a wound thickness.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for evaluating the quality of pearls, and more particularly to an apparatus for evaluating the quality of pearls whose quality is evaluated by the thickness of the pearl winding.

[0002]

2. Description of the Related Art In the jewelery industry, quality control of pearls is being clarified in order to prevent the distribution of poor pearls. The pearl quality evaluation items include color, scratch, shape, size, brilliance, nacre (so-called “roll” formed on the surface of the pearl core), and the like. In gem appraisal,
Although uniform standards have been established internationally for the appraisal of diamonds, the present condition is that the appraisal of pearls has not reached that level. Among the quality evaluation items of pearls, color, scratches, shape, size, and shine can be judged to some extent by external observation, but the pearl winding part cannot be judged from the appearance unlike colors and scratches.

Therefore, conventionally, X-rays have been used to measure the thickness of a pearl winding. This method of utilizing X-rays is to irradiate pearls with X-rays and judge the winding thickness from the shape of the shadow at that time. Judgment of the X-ray shadow shape is made by an expert assessor from X-ray photographs and the like, and it largely depends on the experience and intuition of the assessor.

[0004]

However, the above-mentioned method of utilizing X-rays is based on a complete scientific basis because the witness of the pearl is determined by the assessor based on his experience and intuition. Not an appraisal, but there was room for the subjective elements of the appraiser to be included in the evaluation results. In addition, since the number of skilled appraisers is limited, it was limited to identify the pearls distributed in large quantities in the market.

The present invention has been made in view of the above points, and it is an object of the present invention to accurately measure the thickness of a pearl winding without resorting to a trained expert. An object of the present invention is to provide a pearl quality evaluation device capable of highly reliable pearl evaluation.

[0006]

The present invention has taken the following means in order to achieve the above object. The present invention according to claim 1, wherein an ultrasonic wave is incident on a pearl, a reflected wave from the pearl is received, and a surface reflected wave on the surface of the pearl from the reflected wave and a core and a winding of the pearl are formed. Detecting the interface reflection wave at the interface, calculating the winding thickness of the pearl from the time difference between the surface reflection wave and the interface reflection wave, in the pearl quality evaluation device to determine the evaluation value of the pearl from the obtained winding thickness There is a water tank filled with a coupler liquid for propagating ultrasonic waves, an acoustic lens having a sound wave transmitting and receiving surface side inserted into the water tank from the bottom surface of the water tank, and the pearl inserted in the water tank is the acoustic sound. The pearl holder for positioning with respect to the lens axis of the lens, and the focusing mechanism for raising and lowering the pearl holder to adjust the relative distance between the pearl and the acoustic lens are provided.

According to a second aspect of the present invention, in addition to the above configuration, a cross movement mechanism for moving the acoustic lens in a plane orthogonal to the lens axis of the acoustic lens is provided.

According to a third aspect of the present invention, the center frequency of the ultrasonic wave is a single pulse wave of 25 MHz to 100 MHz.

[0009]

According to the present invention corresponding to claim 1, from the reflected wave of the ultrasonic wave incident on the pearl, the surface reflected wave on the surface of the pearl and the interface reflected wave on the interface between the pearl core and the winding. Is detected, the pearl winding thickness is calculated from the time difference between the two,
The evaluation value of the pearl is obtained from the winding thickness value. Further, in this device for evaluating pearls, the pearl holding section positions the pearl with respect to the lens axis of the acoustic lens, and the pearl holding section is moved up and down by the focusing mechanism. Since the pearl holder and the acoustic lens are provided separately, the relative distance between the pearl held in the pearl holder and the acoustic lens is adjusted, and the pearl can be positioned at the focal position of the acoustic lens. It will be possible.

According to the second aspect of the present invention, while the relative distance between the acoustic lens and the pearl is substantially maintained, the acoustic lens and the water tank are integrated in the XY plane orthogonal to the optical axis of the acoustic lens by the cross movement mechanism. Since it can be moved with, the pearl and the acoustic lens can be aligned.

According to the present invention corresponding to claim 3, the ultrasonic wave most suitable for the evaluation of the winding thickness of the pearl is used, whereby the winding thickness is satisfactorily measured.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, the frequency of ultrasonic waves used will be described with reference to FIG. FIG. 7 shows the relationship between the pearl structure and the reflected waveform. Generally, ultrasonic waves are reflected at the interface where the acoustic properties change. A pearl consists of a core in the center and a nacre (roll) formed around it.
Since it has a layered structure, the ultrasonic wave incident on the pearl is shown in FIG.
As shown in, the light is reflected at the surface of the pearl and at the interface between the pearl layer (roll) and the core. After that, the former is the surface reflection wave,
The latter is called an interface reflected wave.

The time interval between two such reflected waves can be measured using a single pulse ultrasonic wave. However, the winding thickness of pearls is 0.1 mm to less than 1 mm, and the nacre (rolling)
Since the speed of sound of the calcium that composes is approximately 6000 m / sec, the time interval between the surface reflection wave and the interface reflection wave of pearls is roughly calculated as ((0.1-1) × 2) mm ÷ 6000 m / sec = 0.03
~ 0.3 μsec. A generally widely used ultrasonic flaw detector is insufficient to separate and evaluate reflected waves with such short time intervals.

The applicant of the present invention conducted a study to properly evaluate the winding thickness of the pearl, and as a result, the center frequency was 25 MHz.
It has been found that the best results are obtained using a single pulse wave of ~ 100 MHz. Within this range, a center frequency of 90 to 100 MHz is particularly preferable.
With ultrasonic waves having a center frequency lower than this range, it becomes difficult to separate surface reflected waves from interface reflected waves, and with higher frequencies, the attenuation of ultrasonic waves increases and the S / N ratio of the received signal decreases,
No good evaluation can be made in either case.

Based on this result, in the embodiment, the acoustic lens 4 to be described later has a center frequency of 25, 30, 50,
It is possible to arbitrarily select from 75, 90 and 100 (MHz) for use. In response to this, the transmitter 1 described later has a configuration in which a single circuit pulse of each frequency can be switched and transmitted by a known circuit.

For simplification of the transmitter 1, there are about three types of transmission frequencies (eg 30, 50, 100 (MHz)).
Even if the configuration is limited to, it can be practically used. This is because the frequency characteristic of the single-shot pulse wave has a spread that is a mountain shape with the center frequency as a peak, so even if the transmission frequency does not exactly match the acoustic lens frequency, ultrasonic waves with an intensity that does not interfere with measurement can be obtained. Because it will be done. For example, the center frequency of the transmitted wave of 30 MHz is about 25 to 40 MHz, and the center frequency of 50 MHz is 4
About 0 to 70 MHz and 100 MHz may be used for transmission to the acoustic lens of about 70 to 100 MHz, respectively. Outside this range, the intensity of ultrasonic waves generated becomes weak and the S / N ratio decreases. In particular, when the transmission frequency deviates to the side lower than the frequency of the acoustic lens, the lateral resolution of measurement and the like decrease, which is not preferable.

<First Embodiment> FIG. 1 is a diagram showing the overall construction of an embodiment of the present invention. The present embodiment includes a measurement unit that measures the reflection waveform of pearls, and a discrimination document creation unit that analyzes the reflection waveform measured by the measurement unit and evaluates the thickness of the pearl winding.

The measuring unit has a function as a transmitting / receiving means for transmitting / receiving ultrasonic waves to / from the pearl. Transmitter 1
Can be generated by switching a single pulse of each frequency as described above, and the operation is performed via the computer 17. The transmission signal transmitted from the transmitter 1 is
It is applied to the transducer 3 via the circulator 2. The acoustic lens 4 transmits the ultrasonic wave generated by the transducer 3 attached to one end as a spherical wave from the concave sound wave transmitting / receiving surface 4a formed at the other end, and receives the ultrasonic wave reflected from the pearl. To the transducer 3 and convert it again into an electrical signal. The acoustic lens 4 is held by a cross movement mechanism described later. The pearl S is held by a pearl holder 5 described later, and is placed in the vicinity of the focus position where the ultrasonic waves converge. The sound wave transmitting / receiving surface 4a and the pearl S are arranged in a water tank 6 filled with water W as a coupler liquid for propagating ultrasonic waves.

The signal slicing section 7 is a preamplifier 11 for amplifying a reception signal transmitted from the acoustic lens 4 via the circulator 2, and a gate 12 connected to its output terminal.
And a gate signal generation circuit 13 for setting the cutout position and width of the reception signal cut out by the gate 12. By operating the gate 12 so that the input signal passes only while the gate signal is on, only the signal component of the predetermined period can be extracted from the received signal. The position and width of the gate are determined by the gate generation circuit 1 via the computer 17.
It can be adjusted by operating 3.

The digital oscilloscope 8 includes an A / D converter 14 for quantizing the received signal cut out by the signal cutting section 7 at a predetermined sampling frequency, and the A / D converter 1.
A buffer memory 15 for storing the output of No. 4 as reflection waveform data and a monitor 16 for displaying the reflection waveform data stored in the buffer memory 15 are provided.

On the other hand, the identification document creating unit reads the reflected waveform data stored in the buffer memory 15 of the digital oscilloscope 8 to measure the thickness of the pearl winding and evaluate the quality, and a time difference detecting means and a thickness calculating means. Computer 17 as a monitor and a monitor 1 for displaying a reflection waveform
8 and a printer 19 for printing the evaluation result on the identification document. (Note that as described above, the computer 17
Also has a function as an operating means of the measuring unit. )

Next, with reference to FIG. 2, a focusing mechanism for raising and lowering the pearl holding portion will be described. FIG. 2 is a front sectional view of the measurement unit portion of this embodiment. XY stages 31 and 32 (described later) as a cross movement mechanism capable of moving in the left-right direction and the vertical direction on the paper surface are provided on a circular flat plate-shaped base 30, and a cylindrical lens support having a flange at the center of the upper portion thereof. The ring 33 is fixed. Inside thereof, a cylindrical lens frame 34 is detachably attached without play. A flat flange 35 is screwed to the upper part of the lens frame 34, and the acoustic lens 4 is fixed thereon with the sound wave transmitting / receiving surface 4a facing upward. A transducer 3 is built in the acoustic lens 4, and transmission and reception signals are transmitted by a cable (not shown) connected to the connector 4b. The lens frame 34 is fixed by a set screw 36 screwed into a screw hole 33a penetrating the side surface of the lens support ring 33.
It is fixed so that it does not come off.

Four support legs 37 are erected on the upper surface of the flat flange 35, and the circular water tank 6 is supported on the upper ends thereof. There is a circular opening in the center of the bottom surface of the water tank 6, and the acoustic lens 4 is fixed by a lens fixing ring 38 so that the sound wave transmitting / receiving surface 4 a thereof projects into the water tank 6. The acoustic lens insertion portion is hermetically sealed with O-rings 39a and 39b.

Four support legs 4 are provided around the upper surface of the base 30.
0 is erected, and a cylindrical holding ring 41 having a thread groove inside is mounted on the upper end thereof. The center of the retaining ring 41 is arranged so as to substantially coincide with the axial center of the acoustic lens 4. A cylindrical lifting ring 42 having a thread groove on the outer peripheral surface is screwed into the thread groove of the holding ring 41. The diameter of the upper end of the outer peripheral surface is one step thicker, and the knurled 42a
Are formed. Two pins 43a and 43b are planted on the upper end surface of the lifting ring 42 at positions facing each other with the cylinder axis interposed therebetween.

The pearl holding portion is composed of a plate holding member 44 and a positioning plate 46. The plate holding member 44 is composed of a central portion having a U-shaped cross section and flange portions protruding from both ends thereof, and the holes 43a and the long holes which are large enough to fit the pins 43a and 43b into the flange portion. 44b is provided. Further, a round hole is provided at the bottom of the U-shaped portion, and pins 45a and 45b are provided upright at positions facing each other across the round hole. The plate holding member 44 is removably mounted on the lifting ring 42, in which case the pins 43a and 43b are respectively inserted into the holes 44a,
The mounting position is uniquely determined by fitting the mounting position in the long hole 44b. By making one of the two holes an elongated hole, the gap between the pin and the hole can be tolerated.

The plate-shaped positioning plate 46 is provided with a pearl mounting hole 46c whose diameter changes conically in the plate thickness direction at the center thereof. The minimum diameter of the pearl mounting hole 46c is set smaller than the diameter of the pearl S, and the pearl S can be held in a state where the pearl S projects from the bottom of the positioning plate 46. Holes 46a and elongated holes 46b, which are sized to fit the pins 45a and 45b without play, are provided at positions facing each other across the pearl mounting hole 46c. The positioning plate 46 is removably mounted on the plate holding member 44, and the positions thereof are the pins 45a, 4 and
5b, the hole 46a, and the long hole 46b are fitted together to uniquely determine. It should be noted that one of the two holes is a long hole to allow a gap between the pin and the hole.

The fixing positions of the plate holding member 44 and the positioning plate 46 are set so that the center of the pearl S and the screw axis of the lifting ring 42 are aligned when the pearl S is mounted in the pearl mounting hole 46c.

Next, with reference to FIG. 3, an XY stage as a cross movement mechanism for moving the acoustic lens 4 in a plane orthogonal to the lens axis will be described. FIG. 3A is a sectional view taken along the line AA of the measurement unit shown in FIG. 2, and FIG. 3B is a front view with the upper half omitted. An X stage 31 is pivotally supported by a pivot 50 on a base 30. Adjustment mechanisms 51 to 54, which are composed of screws and nuts for rotating the X stage 31 about the pivot 50, are provided at portions of the X stage 31 facing the pivot 50. Reference numeral 51 denotes a stage side fixing member fixed to the X stage 31, and a moving screw 52 is screwed and fixed to a screw hole penetrating this member. A handle 53 composed of a nut is screwed into the moving screw 52, and a position regulating member 54 fixed to the base 30 is provided so as to sandwich the handle 53 from both sides.

On the X stage 31, the X stage 31
Similarly to the above, a Y stage 32 including a pivot 50 'and adjusting mechanisms 51' to 54 'is provided. Y stage 32
The axial support position of is shifted by 90 degrees with respect to the X stage 31 when viewed from the center of the stage.

Next, the operation of this embodiment configured as described above will be described. First, the type of the acoustic lens 4 to be used is selected, assembled into the lens frame 34 and the water tank 6, the water tank 6 is filled with an appropriate amount of water, and the lens support ring 33 of the main body is inserted, and the set screw 36 is tightened and fixed. Next, the pearl S is placed in the pearl mounting hole 46c of the positioning plate 46. As described above, the pearl is held in a state where the pearl S projects from the bottom of the positioning plate 46, and the pearl mounting hole 46c is a conical hole, so that the pearl is always placed at the same position.

To align the acoustic lens 4 and the pearl S, X
The Y stages 31 and 32 are used. When the handle 53 of the X stage 31 is rotated, the handle 53 moves the moving screw 5
Trying to screw in the X direction while rotating the outer circumference of 2. However, the base 30 is placed so that both sides of the handle 53 are sandwiched.
Since the position regulating member 54 fixed to the
The handle 53 does not move in the X direction but moves relatively.
2 moves in the X direction. The moving screw 52 is the X stage 31.
Is fixed to the X stage 31, while the X stage 31 is a pivot 50.
Since it is pivotally supported by the base 30 by the
The stage 31 rotates about the pivot 50. Similarly, when the Y handle 53 ′ is rotated, the Y stage 32 rotates about the pivot 50 ′ with respect to the X stage 31. Since this rotation is performed within a slight angle range, it can be regarded as a linear movement in the XY directions. Therefore, the acoustic lens 4 and the water tank 6 which are fixed on the Y stage 32 are integrated with the pearl S by X.
Move in Y direction.

Focusing is performed by rotating the lifting ring 42 by operating the knurled portion 42a. Since the holding ring 41 screwed to the lifting ring 42 is fixed to the base 30, the lifting ring 42 moves in the vertical direction while rotating by the screw groove. Therefore, the plate holding member 44 integrally fixed to the lifting ring 42 also moves up and down while rotating, and as a result, the relative distance between the pearl S and the acoustic lens is adjusted. At this time, since the mounting position of the pearl S coincides with the screw axis center of the lifting ring 42, the core of the pearl S and the acoustic lens 4 is not displaced by the rotation of the lifting ring 42, and only the relative distance is changed. To do.

In the above adjustment, it can be determined that the point at which the magnitude of the reflected wave from the pearl S is maximum is in the in-center state or the in-focus state. In the actual work, the position of the pearl S or the acoustic lens 4 may be adjusted so that the height of the reflected waveform displayed on the monitor 16 of the digital oscilloscope 8 is maximized.

After the centering and focusing are completed, the electric control system is adjusted. First, the transmission frequency of the transmitter 1 is set according to the acoustic lens 4. Further, the gate signal is set at a timing at which the surface reflected wave of the pearl and the interface reflected wave of the pearl layer (winding) and the core can be cut out together. For these settings, in addition to manual settings by the operator, use a status box that stores information such as transmission frequency and gate timing according to the type of acoustic lens, and read the contents of this status box into the device. You may make it set automatically. Further, the voltage range, time axis, etc. are set for the digital oscilloscope 8.

When the power supply of the device is on, the pulse controller 9 gives a transmission trigger to the transmitter 1 at predetermined intervals, and the transmission signal set by the transmitter 1 is transmitted. The transmission signal is applied to the transducer 3 via the circulator 2 and converted into ultrasonic waves. This ultrasonic wave propagates in the acoustic lens 4, is transmitted as a convergent spherical wave from the sound wave transmitting / receiving surface 4 a, and is incident on the pearl S.

The reflected wave reflected by the pearl S and received by the acoustic lens 4 is converted by the transducer 3 into a received signal which is an electrical signal. The received signal is input to the preamplifier 11 via the circulator 2 and the voltage level is adjusted, and then input to the signal cutout unit 7.

The signal cutout unit 7 operates so as to cut out a signal including a surface reflected wave and an interface reflected wave at the same time with respect to the input of the received signal. Since the approximate value of the time interval Δt between the surface reflected wave and the interface reflected wave is known in advance, the gate signal generation circuit 13 generates a gate signal having a time width slightly larger than this value. Then, the position of the gate signal is adjusted so that both the surface reflected wave and the interface reflected wave are included in the gate signal. Thus, the gate 12 extracts the reflected waveform signal including only the surface reflected wave and the interface reflected wave from the received signal as shown in FIG. Further, the time from the transmission signal being transmitted by the transmitter 1 to the surface reflected wave reaching the gate 12 can be known in advance from the test result or the calculation. Therefore, this time and the time interval Δt described above are gated. It is also possible to set it in the signal generation circuit 13 and eliminate the need for gate signal adjustment.

In the digital oscilloscope 8, the reflected waveform signal input from the signal cutting section 7 is converted into reflected waveform data composed of a digital signal by the A / D converter 14. The reflected waveform data has the horizontal axis on the time axis, and each peak value of the surface reflected wave and the interface reflected wave is represented by the number of bits.
Such reflected waveform data is stored in the buffer memory 15 with the time axis replaced with an address and displayed on the monitor 16.

On the other hand, the computer 17 operates based on the flow chart shown in FIG. 4 to execute the pearl winding thickness calculation and the quality evaluation calculation. That is, by reading the reflected waveform data from the buffer memory 15 and recognizing the number of bits in the read address order (= along the time axis),
Detect the peak value of the reflected waveform.

By the way, there are a plurality of peak values for both the surface reflected wave and the interface reflected wave. A / D converter 14
The signal value obtained by one sampling is called 1 dot. In this embodiment, when a signal smaller than the lower limit (absolute value) continues for n dots or more and the signal value exceeds the upper limit, the position is recognized as a peak value. Then, the number of dots from the first peak value detection position corresponding to the surface reflected wave to the next peak value detection position corresponding to the interface reflected wave is counted. Further, the time per dot (referred to as unit time) which is found from the sampling frequency in the A / D converter 14 is stored in advance, and this is multiplied by the recognized number of dots to multiply the surface reflection wave to the interface reflection. The time interval Δt to the wave is calculated. The time interval Δt may be directly read by the operator from the reflected waveform displayed on the monitor 16 of the digital oscilloscope 8 and input to the computer 17.

Next, the previously entered nacre (roll)
The sound velocity V of is read and the winding thickness T of the pearl S is calculated from the following equation. T = V × Δt / 2 Next, according to the value of the winding thickness T, the evaluation value regarding the winding of the pearl S is determined with reference to the table in which the winding thickness and the evaluation value are associated with each other. Further, other evaluation items (color, scratch, shape, size, brilliance, etc.) are inputted from the input means (not shown), and the respective evaluation values of these evaluation items and the winding evaluation value are inputted into a predetermined calculation formula. Determine the overall evaluation value.

When the comprehensive evaluation of the pearl S is completed, it is determined whether or not a pearl identification document for the pearl is prepared. When the creation is requested, the format data of the pearl identification document as shown in FIG. 5 is read from the built-in memory. It is assumed that the memory stores in advance the format data corresponding to the format of the pearl identification document. Then, each evaluation value is written in the corresponding portion of the format data to create the identification document data, which is sent to the printer 19. The printer 19 prints the identification document data on the identification document sheet and outputs the identification document. Further, when there is no request for creating the identification document, the reflected waveform and the measured value of the winding thickness are displayed on the monitor 18, and the identification document data is stored in an external storage device (not shown).

As described above, according to this embodiment, the time difference Δt between the surface reflected wave and the interface reflected wave is detected from the reflected wave when the ultrasonic wave is incident on the pearl S, and the winding thickness of the pearl S is detected from the value. Since the calculation is made, the pearl quality can be evaluated highly objectively and reliably without depending on the expert. In addition, the objectivity and reliability of quality evaluation can be significantly improved as compared with the conventional method of visually determining the shadow shape of an X-ray image on a pearl.

In the structure of this embodiment, the focusing mechanism for focusing is provided on the side of the pearl holder, so that the acoustic lens 4
There is no need to place a focusing mechanism underneath and the height of the device can be reduced. Further, by loosening the set screw 36, the water tank 6 and the acoustic lens 4 can be easily removed, so that the water in the water tank 6 and the acoustic lens 4 can be replaced quickly. Further, by preparing an integrated body of the aquarium 6 and the acoustic lens 4 as a unit for each type of the acoustic lens 4, it is possible to save the trouble of removing the acoustic lens 4 from the aquarium 6 and to replace the acoustic lens 4 more quickly. .

Further, by using the signal taking-in function of the digital oscilloscope 8 to cut out the predetermined signal from the received signal, the signal cutting-out section 7 can be simplified. That is, the digital oscilloscope 8 which is generally commercially available has a function of performing A / D conversion and memory by taking an input signal for a predetermined time from a certain timing, and is capable of substantially cutting out a predetermined portion of the input signal. Is. Therefore, if the acquisition time interval is set in advance and the acquisition start timing is input from the outside, signal extraction can be performed. A gate signal can be used as a signal for giving a timing, but the time width adjusting function of the generated signal can be omitted from the gate signal generation circuit 13 because only the time position thereof can be adjusted. Further, if the digital oscilloscope 8 has an external communication function, the acquisition time interval setting can be controlled by the computer 17.

<Second Embodiment> FIG. 6 shows a second embodiment in which a part of the focusing mechanism of the pearl holder is modified. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. Guide rods 60 and 61 having a circular cross section fixed to the holding ring 41 extend toward the plate holding member 44 in parallel with the axis of the acoustic lens 4. A hole 62 and an elongated hole 63 are provided at two positions facing each other with the positioning plate 46 of the plate holding member 44 interposed therebetween.
Nos. 0 and 61 are slidably fitted without play. The plate holding member 44 has projections 47a to 47 at four positions on the back sides of both ends.
d is provided and is supported in the up-down direction by the elevating ring 42 via this protrusion.

The operation of the focusing mechanism configured as described above is performed by the rotation of the lifting ring 42 as in the first embodiment. At this time, since the two guide rods 60 and 61 restrict the rotation of the positioning plate 46, only the lifting ring 42 moves up and down while rotating, and the plate holding member 44 is located at two places on one side, that is, at a total of four places. The projections 47a to 47d move only in the vertical direction while sliding with respect to the lifting ring 42, and do not rotate. Therefore, even if the mounting position of the pearl is slightly deviated from the center of the screw axis of the lifting ring 42, the pearl S and the acoustic lens 4 are not displaced due to the raising and lowering operation. Can be lowered.

It is also possible to implement an apparatus having a simplified structure by omitting the cross movement mechanism from the above-described embodiment. In this case, the integrated body of the acoustic lens 4 and the water tank 6 is adjusted in advance when the device is manufactured and fixed to the base 30 so that the axes of the acoustic lens 4 and the pearl S are aligned. Since the mounting position of the pearl S is uniquely determined as described above, the pearl S can be evaluated in a state where the axes of the acoustic lens 4 and the pearl S are substantially aligned without the XY stage. Therefore, it is possible to realize a pearl quality evaluation device having a simpler structure and lower cost. Further, as the focusing mechanism of the pearl holding portion, a known mechanism such as cam drive, friction drive, and telescopic method can be used in addition to the embodiment.

Further, in the embodiment, the winding thickness of the pearl is once calculated, and then the evaluation value relating to the winding is calculated based on this winding thickness. However, when only the winding evaluation needs to be performed ( For example, if the winding thickness is below a certain value,
In the case of bouncing as a defective product), the evaluation value regarding the direct winding is obtained from the detected time difference Δt, or the time difference Δt
You may use itself as an evaluation value. When the speed of sound of the nacre (winding) is almost the same, this is sufficient for evaluation.

[0050]

According to the present invention, it is possible to accurately measure the thickness of a pearl winding without relying on a trained expert, and based on that, it is possible to evaluate a pearl with high reliability. It is possible to provide a quality evaluation device for pearls.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a pearl quality evaluation device that represents a first embodiment of the present invention.

FIG. 2 is a front sectional view of a measuring unit portion of the pearl quality evaluation device shown in FIG.

FIG. 3 (a) is an AA of the measurement unit shown in FIG.
Sectional view taken in the direction of the arrow, (b) is a front view with the upper half omitted.

FIG. 4 is a flowchart showing a calculation operation of a winding thickness and a quality evaluation value of the computer 17.

FIG. 5 is a diagram showing a format example of a pearl discrimination document.

FIG. 6 is a front sectional view showing a second embodiment of the measuring unit.

FIG. 7 is a diagram showing a relationship between a pearl structure and a reflected waveform.

[Explanation of symbols]

 S Pearl W Water (coupler liquid) 1 Transmitter 2 Circulator 3 Transducer 4 Acoustic lens 5 Pearl holding part 6 Water tank 7 Signal cutting part 8 Digital oscilloscope 17 Computer 18 Monitor 30 Base 40 Supporting leg 31 X stage 32 Y stage 41 Holding ring 42 Lifting ring 44 Plate holding member 46 Positioning plate 46c Pearl mounting hole 50, 50 'Pivot 51, 51' Stage side fixing member 52, 52 'Moving screw 53, 53' Handle 54, 54 'Position regulating member

Claims (3)

[Claims] 1. An ultrasonic wave is incident on a pearl, a reflected wave from the pearl is received, and a surface reflected wave on the surface of the pearl from the reflected wave and an interface at an interface between the pearl core and the winding are provided. A pearl quality evaluation device, which detects a reflected wave, calculates a pearl winding thickness from the time difference between the surface reflected wave and the interface reflected wave, and obtains a pearl evaluation value from the obtained winding thickness. A water tank filled with a coupler liquid for propagating sound waves, an acoustic lens having a sound wave transmitting / receiving surface side inserted into the water tank from the bottom surface of the water tank, and the pearl inserted in the water tank is the lens axis of the acoustic lens. A pearl quality evaluation device, comprising: a pearl holding portion for positioning the pearl holding portion; and a focusing mechanism that raises and lowers the pearl holding portion to adjust a relative distance between the pearl and the acoustic lens. 2. The pearl quality evaluation device according to claim 1, further comprising a cross movement mechanism for moving the acoustic lens in a plane orthogonal to a lens axis of the acoustic lens. 3. The pearl quality evaluation device according to claim 1, wherein the ultrasonic wave is a single-shot pulse wave having a center frequency of 25 MHz to 100 MHz.