KR101770771B1 - Apparatus for measuring weights - Google Patents

Apparatus for measuring weights Download PDF

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Publication number
KR101770771B1
KR101770771B1 KR1020160003145A KR20160003145A KR101770771B1 KR 101770771 B1 KR101770771 B1 KR 101770771B1 KR 1020160003145 A KR1020160003145 A KR 1020160003145A KR 20160003145 A KR20160003145 A KR 20160003145A KR 101770771 B1 KR101770771 B1 KR 101770771B1
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KR
South Korea
Prior art keywords
load cell
light
light beam
reflector
weight
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KR1020160003145A
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Korean (ko)
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KR20170083812A (en
Inventor
김동진
이장호
조규만
박준규
박종현
윤승현
임효섭
최재우
Original Assignee
주식회사 카스
서강대학교산학협력단
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Priority to KR1020160003145A priority Critical patent/KR101770771B1/en
Priority to PCT/KR2017/000287 priority patent/WO2017122979A1/en
Publication of KR20170083812A publication Critical patent/KR20170083812A/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G3/00—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances
    • G01G3/12—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
    • G01G3/125—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing wherein the weighing element is an optical member
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/16—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge
    • G01B11/161—Measuring arrangements characterised by the use of optical techniques for measuring the deformation in a solid, e.g. optical strain gauge by interferometric means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02001—Interferometers characterised by controlling or generating intrinsic radiation properties
    • G01B9/0201—Interferometers characterised by controlling or generating intrinsic radiation properties using temporal phase variation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02017—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations
    • G01B9/02021—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations contacting different faces of object, e.g. opposite faces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01G—WEIGHING
    • G01G3/00—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances
    • G01G3/12—Weighing apparatus characterised by the use of elastically-deformable members, e.g. spring balances wherein the weighing element is in the form of a solid body stressed by pressure or tension during weighing
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B26/00—Optical devices or arrangements for the control of light using movable or deformable optical elements
    • G02B26/08—Optical devices or arrangements for the control of light using movable or deformable optical elements for controlling the direction of light

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

The weight measuring apparatus according to the present invention comprises a hollow portion passing through a body, an upper connecting portion connecting upper portions of the first and second fixing portions at both ends of the body, A load cell including a lower connection part for connecting the load cell; A target reflector attached to a bottom surface of the upper connection portion corresponding to a position where a load of the upper connection portion is applied; A reference reflector attached to a bottom surface of the lower connection part; A first light beam reflected by the target reflector and a second light beam incident on the reference reflector and reflected by the second light beam, A path displacement calculation unit; And a weight calculating unit for calculating a weight based on the displacement of the load cell corresponding to the path displacement of the light.
This makes it possible to measure the weight with a high precision measurement range using a laser.

Description

{APPARATUS FOR MEASURING WEIGHTS}

The present invention relates to weight measurement, and more particularly, to an apparatus for measuring the weight of an object to be measured placed on a load cell using an interferometer in weight measurement using a load cell.

The scale is a device for measuring the load of the object to be measured. In the past, the electromagnetic force measuring method and the electric resistance measuring method have been used.

The electronic equilibrium measurement method is a method of measuring the weight by measuring the amount of electricity required when an electromagnetic force sufficient to balance with the load is applied. The measuring capacity ranges from a few milligrams to several kilograms and has a relatively high precision. However, There is a problem in that the mixing of ambient noise is adversely affected to adversely affect the accuracy and stability, the measurement range is too small, and the structure is relatively complicated.

Electric resistance wire method is also called load cell method. It is a method of measuring strain by converting strain of load cell by load into electrical signal by using strain gauge. The load cell scale is made of a structure including a load cell manufactured to be securely deformed in a load range of a region to be measured, a load applying means for applying a load to the load cell, a seat plate on which a measured object is mounted, an outer case, and a control unit. The load cell scale can measure only the load of a specific area that can be measured by the built-in load cell, and thus, a scale having two load cells is also proposed to selectively measure loads in a plurality of areas.

The relative accuracy of the electrical resistance wire type is lower than that of the electronic balance type electronic balance, and when the load cell is increased, the A / D conversion speed is lowered and the accuracy is lowered, and there is also a problem of regular calibration according to the aging of the load cell.

Therefore, a new method for precise weight measurement capable of solving the problem of the electromagnetic force equalizing method or the electric resistance wire method is required.

In the case of an interferometer measuring the length of a light path, there is a problem that the precision is excellent but the dynamic range is generally limited by the wavelength of light. Therefore, in order to utilize the interferometer as a scale, a measure for increasing the measurement range is required.

An object of the present invention is to provide an apparatus for measuring the weight of an object to be measured placed on a load cell using an interferometer having a high measuring range and high precision.

The above-described object is achieved by providing a hollow portion through a body according to an embodiment of the present invention, including an upper connecting portion connecting the first fixing portion at both ends of the body and an upper portion of the second fixing portion, and a lower connecting portion connecting the lower portion Load cell; A target reflector attached to a bottom surface of the upper connection portion corresponding to a position where a load of the upper connection portion is applied; A reference reflector attached to a bottom surface of the lower connection part; A first light beam reflected by the target reflector and a second light beam incident on the reference reflector and reflected by the second light beam, A path displacement calculation unit; And a weight calculating unit for calculating a weight based on the displacement of the load cell corresponding to the path displacement of the light.

At this time, the reference reflector may be attached at a position laterally spaced from a straight line with the target reflector so as not to obstruct the path of the first light beam.

The lower connection part of the load cell may be formed with a through hole at a position in a straight line with the target reflector so as to form a path of the first light beam in a direction perpendicular to the target reflector.

The first light beam is incident on the target reflector through the through hole, and the second light beam is incident on the second reflector through the through- And may further include a mirror to be incident on the reference reflector.

According to the weighing apparatus as described above, it is possible to measure a weight with a high precision measurement range using a laser.

1 is a perspective view of a part of a weighing apparatus according to the present invention;
2 is a block diagram of a configuration for performing processing for calculating a weight of a weighing apparatus according to the present invention;
3 is a block diagram of a reference table used for weight calculation in a weight measuring apparatus according to an embodiment of the present invention;
4 is a schematic diagram illustrating an embodiment of an interferometer applicable to the present invention; And
FIG. 5 is a flowchart of a method of measuring a weight using the weight measuring apparatus of FIG. 1;

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

The weight measuring apparatus according to an embodiment of the present invention includes a hardware module including a load cell and a module for processing the interference light through the interferometer and calculating the weight of the object to be measured.

FIG. 1 is a perspective view of a part of a weighing apparatus 1 according to an embodiment of the present invention, and FIG. 2 is a block diagram of an arrangement for performing processing for calculating a weight of the weighing apparatus 1. Hereinafter, the external configuration of the weighing apparatus 1 and the configuration for the weight calculating process will be described with reference to FIG. 1 and FIG.

1 and 2, a weight measuring apparatus 1 according to an embodiment of the present invention includes a load cell 10, an interferometer 20, a mirror 30, a through hole 40, an optical path displacement calculating unit 50, and a weight calculating unit 60.

The load cell 10 is provided with a hollow portion 11 which penetrates through the center of a body having a substantially rectangular bar shape toward the side and is fixedly attached to the upper end of the load cell supporting means 12. The load cell 10 includes a first fixing part 13 and a second fixing part 14 located at both sides of the body with respect to the hollow part 11 and includes a first fixing part 13, The upper electrode 14 is connected to the upper electrode 15 via a bridge connecting the upper portion of the load cell 10 and the lower electrode 16 via a lower electrode.

The load cell 10 has a structure in which a displacement occurs due to a load of a measured object applied between the first fixing part 13 and the second fixing part 14, And arrows indicate that a load is applied to the area. Meanwhile, the load cell 10 according to the present invention may be implemented as a load cell for precision measurement.

The target reflector 21 and the reference reflector 23 shown in FIG. 1 are disposed in the interferometer 20 in order to detect the displacement of the load cell 10, which is twisted due to the load of the object to be measured, Corresponds to a part of the structure of the interferometer 20.

The target reflector 21 is attached to the bottom surface of the upper connecting portion 15 where the load cell 10 is displaced due to a load applied thereto and the reference reflector 23 is attached to the lower connecting portion 16 where no displacement occurs, As shown in FIG. On the other hand, the reference reflector 23 is located at a position laterally spaced from the straight line with the target reflector 21 so as not to obstruct the light path to the target reflector 21.

The mirror 30 reflects the first light beam r1 and the second light beam r2 which are incident on the lower side of the load cell 10 in the lateral direction as shown in Fig. 1, Is incident on the target reflector 21 and the second light beam r2 is incident on the reference reflector 23.

On the other hand, the mirror 30 is supported by the mirror supporting means 35 fixed to the load cell supporting means 12. The mirror support means 35 is of a "C" shape and is provided in a structure that covers a partial area of the lower connection portion 16 corresponding to the position of the target reflector 21.

The through hole 40 is a hole formed through the lower connection portion 16 and the mirror support means 35 and forms a light path to the target reflector 21. The through hole 40 is formed so as to be parallel to the target reflector 21 such that the first light beam r1 is incident on the target reflector 21 in a direction perpendicular to the direction in which the load is applied, Located.

As described above, the weighing apparatus 1 according to the embodiment of the present invention has an effective structure for employing the structure of the interferometer in the load cell balance.

2, the weight measuring apparatus 1 according to the present invention includes a light path (not shown) for performing processing for calculating the weight of the object to be measured based on the interference light detected through the interferometer 20, And further includes a displacement calculating section 50 and a weight calculating section 60.

When a load is applied to the load cell 10, the position of the target reflector 21 changes due to the warping of the load cell 10, and therefore the length of the path of the interference light due to the two light beams reflected from the target reflector 21 and the reference reflector 23 There is a change.

The optical path displacement calculation unit 50 counts the fringes included in the interference light of the two light beams reflected from the target reflector 21 and the reference reflector 23, And compares the calculated path length of the light with the reference path length corresponding to the path length of the light before the load is applied to the load cell 10 to calculate the path displacement of the light generated by the application of the load. For this purpose, the optical path displacement calculation unit 50 is implemented including a signal processing configuration for amplifying the electrical signal converted from the interferometer 20, analog-to-digital (A / D) conversion, and signal filtering.

The weight calculating unit 60 calculates the weight of the object to be measured based on the displacement of the load cell 10 corresponding to the light path displacement caused by the application of the load. At this time, a reference table in which weight information corresponding to the displacement of the load cell 10 is recorded can be used as a data table showing the correlation between the displacement of the load cell and the weight.

3 shows an example of a reference table showing the correlation between the weight and the distance used in calculating the load.

The reference table of FIG. 3 shows the degree of warpage of the load cell 10 when the load is applied to the load cell 10, that is, the length of the load cell 10 in the center of the load cell 10 and descending in the direction of the ground. In the table of Fig. 3, gf represents a unit of weight.

If there is no weight value corresponding to the displacement of the load cell 10 in the reference table, the weight calculating unit 60 predicts weight values that are not present in the table by various regression methods such as spline.

1, only the target reflector 21 and the reference reflector 23 are shown as the configuration of the interferometer 20, but the weight measuring device 1 may be included in other conventional interferometers including a light source (not shown) Of course.

Hereinafter, an example of the interferometer 20 applicable to the present invention will be described. A variety of interferometers such as a Michelson interferometer and a Mach-Zehnder interferometer may be used as the interferometer 20, but the system of the Michelson interferometer will be described below as an example of the interferometer 20.

The Michelson interferometer, which uses two beams, is composed of a probe beam and a reference beam. The change in phase or amplitude induced in the probe beam due to the physical change to be measured is used as the reference beam to interfere with the reference beam. It is possible to measure the physical quantity with a very high accuracy.

In such an interferometer using two light beams, a homodyne interferometer is used when the frequencies of the light beam and the reference light are the same, and a heterodyne interferometer is used when the frequencies of the light beams are different. In the homodyne interferometer, the phase and amplitude changes can be directly demodulated to the baseband. On the other hand, in the case of the heterodyne interferometer, since the frequencies of the two lights are different, An additional demodulation process is required for the IF (Intermediate Frequency) signal given by mixing.

Although additional demodulation process is required, it is possible to easily measure the phase and amplitude changes by using I / Q demodulation technique, which is widely used in RF communication, without using a complicated optical system. Heterodyne I / Q Interferometers are suitable for sensor applications.

4 is a structural view showing an example of an interferometer 20 applicable to the present invention.

4, an AOM heterodyne interferometer 20 according to the present invention includes a light source 200, a polarizing beam splitter (PBS) 210, a mirror 211, an AOM A quartz-wave plate 230, a collimation lens 240, a target reflector 250, a reference reflector 251, and an A / A first photodetector 260, a second photodetector 261, a differential amplifier 270, and a demodulator 280. The first photodetector 260, the second photodetector 261,

The light source 200 provides a beam of linearly polarized light in a single mode and provides a horizontally aligned beam of light on the optical axis incident surface of the PBS.

A polarizing beam splitter (PBS) 210 is an element that transmits or reflects incident light according to a polarization state. The P-wave is transmitted as it is and the S-wave is reflected perpendicularly to the incident angle. Accordingly, the polarized beam splitter (PBS) 210 transmits the P wave provided from the light source 200 as it is and provides it to the AOM 220.

The AOM 220 vibrates at a driving frequency f RF by the AOM driving unit 221. As a result, a part of the incident light beam is modulated with a zero frequency -order light, and a part of the incident light is modulated by the driving frequency f RF and output as a first-order light. At this time, the primary beams having a frequency of zero-order beams, and (f 0 + f RF) with a frequency of f 0 is output to each other, separated by a predetermined angle. The collimation lens 241 outputs the quadrangular comb and the primary light beam, which are separated and output at a predetermined angle, in parallel. The light rays of the P wave incident on the acoustooptic modulator 220 become an S wave that is a linearly polarized state rotated by 90 degrees from the P wave due to the characteristics of the AOM 220 as it passes through the AOM 220. [

The AOM driver 221 drives the AOM 220 according to the driving frequency and provides the demodulator 270 with information on the driving frequency f RF for detecting the signal light.

Since the QWP 230, which is a λ / 4-phase delay plate, is arranged at 45 °, when the linearly polarized light of the S wave is incident, the circularly polarized light is converted and output. When the circularly polarized light is incident, . The QWP 230 is disposed between the target reflector 250 and the reference reflector 251 and the AOM 220 and reflects the first and second light beams reflected from the target reflector 250 and the reference reflector 251 And rotates the polarization state so as to be 90 degrees with respect to the original polarization direction, and outputs the rotated state.

The target reflector 250 is vertically disposed on the path of one of the beams output from the AOM 220. The target reflector 250 reflects the incident light and outputs along the incident path. When the position of the target reflector 250 moves and the distance to the target reflector 250 changes, And provides the included probe beam.

The target reflector 250 of the optical interferometer according to the present embodiment functions as a target reflector 21 attached to the bottom of the upper connection portion 15 of the load cell 10 shown in FIG. Serves as a reference reflector 23 attached to the bottom surface of the lower connection portion 16 of the load cell 10.

The reference reflector 251 is vertically disposed on the path of the other one of the beams output from the AOM 220. As a result, the light output from the AOM 220 proceeds to the reference reflector 251 and is again incident on the AOM to provide a reference beam.

The light beam and the reference light reflected from the target reflector 250 and the reference reflector 251 are modulated by the AOM 220 after passing through the collimation lens 240 and the QWP 230 and proceed to the PBS 210 . The two light beams reflected from the target reflection plate 250 and the reference reflection plate 251 pass through the QWP 230 and become P polarized light in circularly polarized light. In addition, each of the light beams re-entered into the AOM 220 is divided into an unmodulated quadrangle and a primary light modulated by the driving frequency. Thus, once the frequency modulated light is again frequency modulated, the frequency difference value of the two beams output from the AOM, that is, the beat frequency, is twice the modulation frequency f RF of the AOM. In addition, the light beam passing through the AOM is rotated by 90 ° and converted into an S wave.

The light beams incident on the PBS 210 are all in the S polarization state. The light beams incident along the first path 'a' are reflected by the PBS to proceed to the first optical detector 260, b ') are reflected by the PBS and input to the second photodetector 261. [

The differential amplifier 270 receives the first and second interference signals from the first and second optical sightswitching devices 260 and 261 and detects the difference value i 1 - i 2 of the input interference signals And outputs it to the demodulator 280.

The driving frequency f RF provided to the AOM 220 through the AOM driving unit 221 is converted to a frequency 2f RF twice and supplied to the demodulation unit 280. The demodulator 280 demodulates the interference signal provided from the photodetector by using twice the frequency to detect a phase and an amplitude change with respect to the signal beam.

There are various methods of demodulating the interference signal. One of them is an I / Q (In-phase / Quadrature-phase) demodulation method. Using the I signal and the Q signal of the interference signal output from the demodulator, The change can be detected. The demodulator 280 receives and demodulates the interference signal and the modulated frequency information, and outputs the I and Q values.

The I value and the Q value output from the demodulator 280 are provided to the optical path displacement calculation unit 50, and the phase change is calculated by the equation (1).

Figure 112016002707209-pat00001

The phase change in Equation (1) measures the change in the fine path length less than 1/4 of the incident light wavelength (l) called fringe. The reason why one fringe is 1/4 of the incident light wavelength is that the light beam is reflected from the target reflection plate 250 and the reference reflection plate 251 and returns to the phase ambiguity. Large displacements greater than one fringe are detected through fringe counting.

Fringe counting is a technique of dividing one fringe into a plurality of zones and adding or subtracting 1/4 of the wavelength of the incident light to the displacement of the target reflector 250 every time the change in the path length of the light changes in a specific direction and goes beyond one fringe range to be.

The demodulator 280 is connected to the optical path displacement calculation unit 50. The optical path displacement calculation unit 50 according to the present embodiment divides one fringe into three zones to detect the direction of the change in the path of the light The number of fringes can be calculated.

FIG. 5 is a flowchart of a method of measuring a weight by the weight measuring apparatus 1 described above with reference to FIGS. 1 and 2. FIG.

In the following description of the embodiment, each step constituting the method of measuring the weight of the present invention can be understood as an operation performed in the corresponding component of the weight measuring apparatus 1 of the present invention explained with reference to Figs. 1 and 2 , Each step constituting the method should be limited to the function itself defining each step. That is, it should be noted that the subject of each step is not limited by the name of the constituent element exemplified by performing each step.

According to the weight measuring method according to the embodiment of the present invention, interference light through the interferometer 20 is first processed (S610).

The two light beams r1 and r2 from the light source are reflected by the mirror 30 so that one light beam r1 passes through the lower connecting portion 16 of the load cell 10 and the mirror supporting means 16, Through the through hole 40 provided in the reflector 35 and is incident on the target reflector 21 and the remaining light beam r2 is incident on the reference reflector 23. The processing of the interfered light reflected from the two reflectors 21 and 23 amplifies the weak electric signal, performs analog-to-digital (A / D) conversion on the amplified signal, (Low Pass Filter), HPF (High Pass Filter), and the like. Meanwhile, the interferometer according to the present invention includes a Michelson interferometer, a heterodyne interferometer, an AOM-based heterodyne interferometer, and a Mach-Zender interferometer as described above.

Thereafter, the length of the optical path of the interferometer 20 is calculated using the shape information of the interference light (S620). At this time, the type information of the interference light includes the number of the fringes included in the interference light and the phase difference information.

When the optical path length is calculated, the optical path displacement is derived by comparing the calculated length of the optical path with the reference path length (S630). Here, the reference path length is the optical path length when no load is applied to the load cell 10.

When the optical path displacement is derived, a length value, which is a displacement of the load cell related to the degree of bending of the load cell 10 corresponding to the optical path displacement, is searched using the reference table (S640) Is defined as the weight of the object to be measured (S650).

According to the weight measuring apparatus 1 of the present invention as described with reference to the above embodiments, an effective structure for employing an interferometer in the load cell balance is provided, and it is possible to provide a structure that can be commercialized beyond the experimental stage There is a technical significance beyond the prior art.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims. It will be possible.

10: load cell 15: upper connection part
16: lower connection part 20: interferometer
21: target reflector 23: reference reflector
30: mirror 40: through hole
50: optical path displacement calculating section 60: weight calculating section
200: light source 210: polarizing beam splitter
220: AOM 221: AOM driving section
230: QWP 240: collimation lens
250: target reflector 251: reference reflector
260: first photodetector 261: second photodetector
270: Differential amplifier 280:

Claims (4)

A load cell including a hollow portion passing through the body and including an upper connecting portion connecting the first fixing portion at both ends of the body and an upper portion of the second fixing portion, and a lower connecting portion connecting the lower portion;
A target reflector attached to a bottom surface of the upper connection portion corresponding to a position where a load of the upper connection portion is applied;
A reference reflector attached to a bottom surface of the lower connection part;
A first light beam reflected by the target reflector and a second light beam incident on the reference reflector and reflected by the second light beam, A path displacement calculation unit;
A weight calculating unit for calculating a weight based on a displacement of the load cell corresponding to a path displacement of the light; And
The first light beam is transmitted through a through hole formed in a lower connection portion of the load cell, which is formed in a straight line with the target reflector, by changing a traveling direction of the first light beam and the second light beam, And a mirror that is incident on the target reflector and allows the second light beam to be incident on the reference reflector.
The method according to claim 1,
Wherein the reference reflector is attached at a position laterally spaced from a straight line with the target reflector so as not to interfere with the path of the first light beam.
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PCT/KR2017/000287 WO2017122979A1 (en) 2016-01-11 2017-01-09 Weight measuring device

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