JP2018169295A - Liquid level height measuring device, liquid injecting device having liquid level height measuring device, and method for measuring liquid level height using level height measuring device - Google Patents

Abstract

To contactlessly measure a change of liquid level in a transparent container with high accuracy without being affected by an environment or enable a change of liquid level in a transparent container to be measured contactlessly when there is difficulty bringing a sensor into direct contact with a liquid level because of the presence of a narrow part in a measurement path.SOLUTION: A liquid level height measuring device 50 measures a liquid level height in a container 30 by a change from a reference height. A length measuring instrument with laser interferometer 100 includes a laser light source, a beam splitter and a laser detector, and is capable of radiating a laser beam. A reflector 18 reflects the laser beam radiated from the length measuring instrument with laser interferometer at the underside of the container. The length measuring instrument with laser interferometer finds a liquid level height, as a change from the reference height, from a difference between the reference optical path length Lof the laser beam radiated from the laser light source and reflected from the reflector when the liquid level height in the container is at reference height and an optical path length Lx at the time the liquid level height is changed, and the refractive index of a liquid 34 under measurement that is included in the container during measurement.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a measuring apparatus for measuring the liquid level in a container, a liquid injection apparatus having the liquid level measuring apparatus, and a liquid level measuring method using the measuring apparatus, particularly through a narrow part. The present invention relates to a liquid level measuring device suitable for measuring the liquid level in a container, a liquid injection device having the liquid level measuring device, and a liquid level measuring method using the same.

  As a method for measuring the liquid level or amount of liquid in a container in a non-contact manner, a method using ultrasonic waves has been proposed. For example, in Patent Document 1, when detecting the liquid level with an ultrasonic transducer attached to the bottom of the container, in order to eliminate an error due to the thickness of the bottom of the container, the ultrasonic transducer is driven in bursts while changing the frequency, and the bottom of the container Ultrasonic waves are emitted toward the liquid surface via Thus, the plate thickness natural frequency is specified, and the plate thickness is corrected when calculating the liquid level of the container based on the received signal of the liquid level reflected wave at the liquid level detection driving frequency.

  Further, in Patent Document 2, when dispensing from a parent sample to a child sample, a vibrator that oscillates and receives ultrasonic waves between the distal end portion of the portion where the dispensing tip of the pump is mounted and the dispensing tip. After the ultrasonic wave is transmitted from the vibrator, the ultrasonic wave propagates to the dispensing tip, and is transmitted to the dispensing tip via the liquid surface of the liquid sample sucked into the dispensing tip. The signal processing circuit measures the liquid level of the liquid sample from the time elapsed from transmission to reception until it is received back.

  On the other hand, the liquid level in the container is also measured using laser light. For example, in Patent Document 3, a laser-type liquid level meter is used to facilitate optical axis alignment and calibration of the measurement distance. The distance meter adjusts the laser beam left and right and back and forth by a fine movement rotation mechanism, and detects the position of the calibration body from the distance measurement by the laser distance meter and the change in the reflected high intensity. The distance is constructed by comparing the known value with the detected value. In Patent Document 4, in order to measure the height without contact, the bubble surface is irradiated with laser light, the reflected light is collected, the phase difference between the incident light and the reflected light is calculated, and the height of the bubble is calculated. Detected.

JP 2011-2326 A JP-A-10-232239 JP 2014-145756 A JP 2001-249042 A

  As described in Patent Document 1 and Patent Document 2, a method of measuring the height of the liquid level in a conventional container using the propagation time of ultrasonic waves is used. At that time, since the ultrasonic wave is reflected by the liquid surface, the distance between the sensor and the liquid surface is calculated based on the propagation time of the ultrasonic wave. However, the liquid level measurement method using ultrasonic waves has the following problems to be solved. One is accuracy and the other is measurement range. Regarding accuracy, the ultrasonic wave propagation time and sound velocity value are required for liquid level measurement, but the sound velocity varies greatly depending on the ambient conditions such as ambient temperature. The measurement accuracy of commercially available sensors using ultrasonic waves is about 1 mm, and general-purpose ultrasonic sensors are not suitable for precise measurement. Regarding the measurement range, the ultrasonic wave transmitted from the ultrasonic sensor has a certain extent. That is, there is a limit to narrowing down the spot diameter of the transmission signal. A generally used ultrasonic sensor has a spread of several tens of millimeters, and it may not be possible to determine exactly which position is being measured.

  On the other hand, in the liquid level detection apparatus described in Patent Document 3 and Patent Document 4 using a laser, there is an advantage that problems of the ambient temperature and the spot diameter of the transmission signal can be avoided. However, in the device described in Patent Document 3, it is necessary to arrange a device that reflects the laser light on the liquid level in the container, and it is allowed to arrange such an obstacle without such a space. If not, it is difficult to use. Furthermore, in the liquid level measuring device described in Patent Document 4, since the laser transmission source is attached to the container, it is easily affected by disturbances such as vibration of the container.

  The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is to accurately measure a change in the liquid level in a transparent container without contact with the environment. Another object of the present invention is to enable non-contact measurement of a change in liquid level in a transparent or opaque container in which there is a narrow portion in the measurement path and it is difficult to directly contact the sensor with the liquid level. .

  A feature of the present invention that achieves the above object is that a liquid level measurement device for measuring the liquid level in a container changes from a reference height, and includes a laser light source, a beam splitter, and laser detection. And a laser interference length measuring device capable of irradiating laser light, and a reflecting material that reflects the laser light emitted from the laser interference length measuring device below the container. Then, the laser interferometer measures the reference optical path length and the liquid level of the laser light irradiated from the laser light source and reflected by the reflecting material when the liquid level in the container is at the reference height. The liquid surface height is obtained as a change from the reference height from the difference in the optical path length during measurement with varying height and the refractive index of the liquid to be measured contained in the container during measurement.

  In the above feature, the container may be a transparent container, the reflective material may be disposed in proximity to the outer surface of the bottom of the transparent container, the container is an opaque container that does not transmit laser light, and the reflective material is the The bottom surface inside the container may be provided integrally with or separately from the container. The apparatus further comprises storage means for storing the refractive index in advance, and the stored refractive index data is obtained by injecting the liquid from a reference height position of the container or a different container to a predetermined height position where the height is known. The laser interferometer is preferably measured by the laser interferometer. The refractive index can also be stored as a table or a formula.

  Another feature of the present invention that achieves the above object is that the liquid injection device includes any one of the liquid level height measurement devices, a liquid injection unit that injects a liquid into the container, and the liquid level height measurement device. It is provided with the control means which controls opening and closing of the injection path of the liquid injection means based on the measured value.

  Furthermore, another feature of the present invention that achieves the above object is to provide a laser beam from a laser interferometer that the liquid level measuring device has on a reflector disposed at the bottom of a container into which a liquid is injected by a known height. And the laser interferometer measures the reflected light reflected from the reflecting material, and injects the liquid into the container and similarly applies a laser to the reflecting material disposed at the bottom of the container. The step of irradiating laser light from the interference length measuring device and measuring the reflected light reflected from the reflector by the laser interference length measuring device and the difference in optical path length obtained by the difference between the two measurement results There is a step of calculating from the refractive index as the amount of change in the liquid level in the container. In this feature, the refractive index may be obtained based on a detection value of a temperature sensor disposed in the vicinity of the container.

  According to the present invention, since the laser light reflector is disposed below the container, even a container having a narrow portion in the measurement path can secure even a space through which the laser light emitted from above the liquid surface can pass. Then, the change in the liquid level can be measured by the reflection of the laser light from the reflector, and the change in the liquid level and the change in the liquid amount in the container can be accurately measured in a non-contact manner regardless of the environment. In addition, even if there is a narrow part in the measurement path and it is difficult to directly contact the sensor with the liquid level, it is possible to measure changes in liquid level and liquid volume in a transparent or opaque container without contact. Become.

It is a fragmentary sectional view which shows the example of a measurement using the liquid level height measuring apparatus which concerns on this invention. It is a schematic diagram explaining the measurement principle of this invention. It is a figure explaining the length measurement principle of the laser length measuring device which concerns on this invention. It is a figure explaining the change of the waveform observed in FIG. It is a figure explaining the correction method according to the physical property of the liquid in a container. It is a graph which shows an example of the liquid physical property value in a container. It is a fragmentary sectional view showing other examples of liquid level height measurement concerning the present invention. It is a fragmentary sectional view which shows the further another Example of the liquid level height measurement which concerns on this invention. It is a fragmentary sectional view showing other examples of liquid level measurement concerning the present invention. It is a flowchart which shows the process sequence of the liquid level method of this invention.

  Hereinafter, an embodiment of a liquid level measuring apparatus according to the present invention will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of one embodiment of a liquid level measuring device 50 according to the present invention. A reflective material 18 having a mirror surface is attached to the outer surface of the container 30 on the bottom surface side of the transparent container 30 in which a medicine such as a syringe or ampoule is accommodated. Further, the reflective material 18 is not directly attached to the outer surface of the container 30 but may be disposed close to the outer surface of the container 30 as will be described later.

  The container 30 is supplied with a liquid 45 such as a chemical from the liquid supply source 40 to the liquid injection means 42 by a liquid supply means such as a pump (not shown). The liquid injection means 42 opens to the opening 32 that forms the narrow portion of the container 30, and a valve means that the liquid supply means has so as to inject a predetermined amount of liquid 34 into the container 30 is a control means (not shown). Control.

  In order to measure the amount of the liquid 34 in the container 30, a laser interference length measuring device 100 is disposed outside the container 30. The laser interference length measuring device 100 emits laser light 24 toward the opening 32 of the container 30, and the emitted laser light 24 is reflected by the reflecting material 18 attached to the outer surface of the bottom surface of the container 30, thereby causing laser interference. Return to the light receiving unit of the length measuring device 100.

  The light receiving unit detects this laser return light and detects the liquid level of the liquid 34 in the container 30. At this time, the temperature of the liquid 34 is detected or approximated by the temperature sensor 60 disposed in the vicinity of or in the container 30, and stored in a storage means included in a control device (not shown) included in the liquid level measuring device 50. From the refractive index ν of the liquid 34 at the temperature measured by the temperature sensor 60 using the refractive index curve or refractive index data (or refractive index table or equation) of the liquid 34, the liquid level of the liquid 34 in the container 30 is obtained. Looking for height. As will be described later, since the refractive index ν of the liquid is relatively insensitive to temperature, the temperature sensor 60 is not necessarily required.

The above is the outline of the measurement according to the present embodiment. The details will be described with reference to FIG. FIG. 2 is a schematic diagram of an embodiment of the liquid level measuring device 50 shown in FIG. The height of the interior volume of the container 30 is L _1, liquid level which is a reference in measuring the liquid level using a liquid level measuring device 50 (initial height) is L _0.

  When the liquid 34 is injected into the container 30 using the liquid injection means 42, the liquid level of the liquid 34 in the container 30 in the middle of the rise of the liquid level Ls is Lx, which is obtained as a measurement value. The liquid level is L.

That is, this liquid level height measurement uses the laser interferometer 100 to measure the change L in the liquid level height from the initial liquid level height L ₀ , that is, the relative liquid level height (Lx−L ₀ ). is intended to measure the liquid level L, a when requiring absolute liquid surface height Lx, it is necessary to determine the initial liquid level height L ₀ as the state liquid is not in the container 30.

  The principle of the laser interferometer 100 for measuring the change in the height of the liquid level Ls will be described with reference to FIGS. FIG. 3 is a diagram showing a configuration of the laser interference length measuring device 100, and FIG. 4 is a diagram showing waveforms of laser emission light (irradiation light) and reflected light generated by the laser interference length measuring device 100.

  A yellow laser beam or a laser beam 20 having a wavelength of 589 nm is irradiated from a laser light source 10 that generates laser light to a beam splitter 12 that is a half mirror. One of the laser beams incident on the beam splitter 12 and divided in two directions is irradiated as a laser beam (reference beam) 26 to the fixed reflecting mirror 14 disposed in the housing 19 of the laser interference length measuring device 100. After that, the light is reflected by the fixed reflecting mirror 14, passes through the beam splitter 12, and enters the detector 16 which is also disposed in the housing 19 of the laser interference length measuring device 100.

  On the other hand, the other of the laser beams divided by the beam splitter 12 is irradiated as the measurement light 24 to the reflecting material 18 having a mirror surface provided at the bottom of the container 30, reflected by the reflecting material 18, and then fixed by the beam splitter 12. Together with the reflected light 26 from 14, it enters the detector 16 as detection light 22.

Here, since the liquid 34 is put in the container 30 and the liquid 34 has a refractive index ν different from that of the atmosphere, the laser light (measurement light) 24 is reflected by the reflecting material 18 at the same position in the space and returned. Nevertheless, the optical path length represented by the product of the laser beam path length L ₁ and the refractive index ν is the length of the liquid 34 portion in the laser beam 24 path, that is, the liquid level of the liquid 34 in the container 30. It changes with height Lx.

Ignore the gap between the laser interferometer length measuring machine 100 and the container 30, with reference to FIG. 2, the distance from the laser interferometer length measuring machine 100 to the reflecting surface of the reflector 18 is L _1, the liquid level measurement initial height at is L ₀ from the reflecting surface of the reflector 18.

At this time, the optical path length A of the laser light (# 20 + # 24 + # 22) emitted from the laser interference length measuring device 100, reflected by the reflector 18 and returned to the laser interference length measuring device 100 is A = 2 × {( Air column) + (liquid column)} = 2 × {(L ₁ −L ₀ ) + 2 × L ₀ × ν}.

Here, ν is a refractive index. On the other hand, the optical path length B when the liquid level rises to Lx is similarly B = 2 × {(air column portion) + (liquid column portion)} = 2 × {(L ₁ −Lx) + 2 × Lx. × ν} = 2 × {(L ₁ −L−L ₀ ) + 2 × (L + L ₀ ) × ν}. Here, the refractive index of air is 1. Therefore, the optical path length difference (A−B) is A−B = 2L (ν−1), and the liquid level height L is obtained by L = (A−B) / 2 (ν−1).

  That is, although the laser light is reflected at the same physical position (reflecting plate 18), as shown by (a) to (d) in FIG. 18d appears to move and behaves like a longer distance or shorter wavelength.

  FIG. 4 shows an example of the waveform of each laser beam 26, 24, 22 at the corresponding liquid level height Lx when the apparent position of the reflector 18 has moved to 18 (a) to (d). The uppermost stage R is the waveform of the laser light (reference light) 26 from the fixed reflecting mirror 14, the middle stage M is the waveform of the laser light (measurement light) 24 from the reflector 18, and the lowermost stage is the two waveforms R. , M is the waveform of the combined light 22. When the liquid level height Lx changes and reaches a certain position, the phases of the laser beam (reference beam) 26 and the laser beam (measurement beam) 24 that come together in the beam splitter 12 match, and the waveform of the synthesized beam 22 is a light source 10 has the same tendency as the original waveform emitted from 10 (state (a)).

  At a certain point where the liquid level height Lx is increased, the phases of the laser beam (reference beam) 26 and the laser beam (measurement beam) 24 differ by 90 ° and are returned to the beam splitter 12, and the waveform of the combined beam 22 is (a) Although the waveform is smaller than the waveform in the state (2), the waveform has the same tendency (state (b)).

  When the liquid level height Lx further increases and the phase of the laser beam (reference beam) 26 and the laser beam (measurement beam) 24 is reversed by 180 °, the waveform of the combined beam 22 becomes 0 (state (c)). When the liquid level height Lx further increases, the phases of the laser beam (reference beam) 26 and the laser beam (measurement beam) 24 differ by 90 ° and are returned to the beam splitter 12, and the waveform of the synthesized beam 22 is the waveform of (b). The waveform has the same tendency as in (state (d)). This occurs every time the optical path length changes according to the wavelength length of the outgoing light 20. Therefore, the liquid level height Lx changes to measure the wave number of the measurement wave that the detector 16 of the laser interference length measuring device 100 reaches, and the waveform is observed to have the same tendency as the outgoing light (the outgoing light is a sine wave). If it is a sine wave) or a waveform whose waveform is zero, the optical path length, that is, the liquid level height L can be measured with a resolution up to about ½ of the wavelength of the emitted light.

  Next, the refractive index ν, which is an important factor in the liquid level measurement, will be described with reference to FIGS. In this liquid level measurement, since the refractive index ν needs to be known, data of the refractive index ν is prepared in advance. FIG. 5 is a diagram showing how the refractive index ν is measured, and FIG. 6 is a graph showing an example of a temperature change of the refractive index ν. FIG. 6 is a diagram showing a temperature change of the refractive index ν when irradiating water with yellow laser light having a wavelength λ = 589.3 nm.

  It can be seen that the refractive index ν changes by about 0.002 (about 0.0075% / ° C.) with a temperature change of 20 ° C. Accordingly, when high-accuracy liquid level measurement is required, the liquid temperature of the liquid to be measured 34 is kept constant. However, in the case of normal measurement in which the liquid level height is measured in a temperature-controlled room atmosphere, the refractive index ν is It can be regarded as almost constant.

The measurement of the refractive index ν corresponds to the case where the initial value L ₀ of the liquid level height is set to 0 in the measurement of the general liquid level height L shown in FIG. The predetermined height (measured height) Lx of the container 30 is also known. To minimize the error of measurement, the predetermined height Lx is desirably to a full liquid state, it is Lx = L _1.

First, a laser beam is irradiated to the empty container of the transparent container 30 having the reflecting material 18 attached to the outer surface of the bottom using the liquid injection port 32, and the reflected light from the reflecting material 18 is irradiated with the laser interference length measuring device 100. The detector 16 receives the light and acquires the initial data A of the optical path length. Next, the liquid to be measured 34 is poured into the container 30 until it is full. Similarly, laser light is applied to the reflector 18 using the liquid injection port 32, and the detector of the laser interference length measuring device 100 receives the reflected light from the reflector 18 to obtain measurement data B of the optical path length. . Since the optical path length is the product of the refractive index ν and the liquid level height L, it can be obtained by ν = (A−B) / 2L ₁ +1.

  By calculating the refractive index ν by changing the liquid temperature of the liquid 34 in the container 30, a temperature calibration curve of the refractive index ν is obtained and stored in the storage means included in the laser interference length measuring device 100. Thereby, if the liquid temperature of the liquid 34 at the time of liquid level measurement is known, the refractive index ν can be easily obtained. As described above, in the case of a liquid such as water, the temperature dependence of the refractive index ν is small, so that the influence of temperature can be ignored by setting the measurement chamber to a constant temperature room or the like.

  Next, another embodiment to which the present liquid level height measuring method is applied will be described with reference to FIGS. FIG. 7 shows a case where the liquid level measurement target liquid is a flammable liquid such as various fuels. This is a case where the laser light is transmitted even if it is a flammable liquid.

  Inflammable liquids are generally highly volatile liquids, and monitoring the liquid level is regarded as important from the viewpoint of preventing accidents. In an ultrasonic sensor conventionally used for measuring the liquid level, since the sensor part is composed of an electric substrate, it cannot be denied that corrosion may occur due to long-term use and an electric spark may occur.

  If an electrical spark occurs, in the worst case, it will ignite the flammable liquid and cause an explosion. Therefore, in this embodiment, a laser interferometer that does not use any electrical device for the interferometer section is used. In that case, the laser interference length measuring device may be disposed near the container as described below, or the laser interference length measuring device is disposed at a position away from the container so as to avoid a flaming accident. Laser light may be guided to the measurement unit with an optical fiber.

  That is, since the liquid 34 contained in the container 30 is combustible, the container 30 is a metal container that is no longer transparent and does not transmit laser light. Therefore, the reflecting material 17 is provided inside the bottom surface of the container 30. When the reflecting material 17 is provided inside the container 30, the reflecting material 17 may be integrated with the container 30, or the reflecting material (mirror) 17 manufactured separately may be attached to the inside of the container 30 by adhesion or the like. Also good. Thereby, even if it is the case of the liquid which could not use an ultrasonic measuring device conventionally, a liquid level height can be measured with high precision.

  FIG. 8 shows a mounting table on which the container 30 is mounted instead of directly attaching the reflective material 18 to the outside of the bottom surface of the container 30 when measuring the liquid level height L of the liquid 34 in the transparent container 30. This is a case where the reflective material 18 is provided on the upper surface of 38. Even if there is a gap between the reflector 18 and the container 30 on the top surface of the mounting table 38, the influence of the gap is canceled in the liquid level height measurement. It can be measured.

  In the case of the present embodiment, it is not necessary to attach the reflective material 18 to each container 30, which is advantageous when measuring the liquid level height L in large quantities. Moreover, if the upper surface of the mounting table 38 is made of transparent glass and the reflective material 18 is attached inside or below the glass, the risk of the reflective material 18 being damaged or soiled by replacing the container 30 is reduced, and work efficiency is improved. To do.

  FIG. 9 is a diagram showing an application to a mass-produced product such as a case where a chemical solution is injected into an ampoule. An empty container 30 is carried to the liquid injection position by a belt conveyor or the like. At the liquid injection position, the liquid 34 is supplied from the liquid supply source 40 to the liquid injection means 42 by a liquid supply means such as a pump (not shown), and the opening and closing of the injection path is controlled by a control means such as a valve (not shown). The injection of the liquid 34 into the container 30 is controlled. When the empty container 30 is first transported to the liquid injection position, the laser beam 24 is irradiated from the laser interference length measuring instrument 100 to the reflector 18 disposed below the container 30. At this time, the reflector 18 is attached to the mounting table 38 side as shown in FIG.

The laser beam 24 transmitted through the container 30 and reflected by the reflector 18 enters the laser interference length measuring device 100 and is received by the detector 16 to measure the optical path length that is the basis of the initial value data of the liquid level measurement. . Next, the liquid 34 is injected from the liquid injection means 42 by controlling a control means (not shown). Once injected continuously measure changes in optical path length in the laser interferometer length measuring machine 100 while continuing reaches a predetermined length, determines that the liquid level L _D is set to a predetermined height, the control means liquid injection To stop.

  When the liquid injection is completed, the belt conveyor is driven and the next empty container 30 is placed at the liquid injection position. The same procedure is repeated thereafter. According to the present embodiment, it is possible to inject a predetermined amount of liquid into an empty container with high accuracy and efficiency.

  Next, the procedure for measuring the liquid level height L of the liquid 34 in the container 30 will be described with reference to the flowchart of FIG. Prior to this measurement, the refractive index ν of the liquid 34 at the temperature of the liquid 34 to be used and the wavelength of the laser beam to be irradiated is obtained in advance. As a master container used for calibration, a container 30 that is the same as or different from the container 30 to be measured is prepared.

  The total height of the internal volume of the master (container) is measured with a depth gauge or the like. If there is only a narrow part where the depth gauge cannot be inserted, the height is measured using another method such as a gravimetric method. Here, a case where a depth gauge is used will be described.

  In step S110, the liquid level height L is measured using the laser interferometer 100 when the master is empty and the liquid 34 is injected into the master up to a predetermined liquid level. When the master can be filled with the liquid, the liquid can be filled and measured, thereby enabling more accurate height measurement as shown in FIG.

  Here, if the depth gauge used for height measurement is inclined from the vertical direction with respect to the liquid level Ls, an error is included in the calibration value of the liquid level height L by an amount deviated from the vertical direction. Accordingly, in step S120, misalignment between the insertion direction and position of the depth gauge is detected.

  This misalignment is detected by irradiating the reflection material 18 with laser light and setting the direction in which the return light coincides with the irradiated light as the true direction, and detecting the inclination of the insertion direction of the depth gauge with respect to the true direction. Based on the detected misalignment of the insertion position of the depth gauge, the insertion position is corrected by tilting the depth gauge in a direction to cancel the inclination of the depth gauge in step S130. Next, the depth gauge is inserted from the normal direction and the master is measured again (step S140).

  Since the calibration using the master is completed, measurement is started for the workpiece (container) 30 that is the actual measurement target (step S150). That is, the workpiece 30 is irradiated with laser light from the laser interferometer 100 to measure the initial state and the liquid filling state.

  Thereafter, the amount of misalignment in which the laser irradiation light of the laser interference length measuring device 100 is deviated from the axis of the workpiece 30 is detected (step S160). Since the misalignment amount is known, the measurement result of the liquid level height L of the workpiece 30 using the laser interference length measuring device 100 is corrected by this amount (step S170). The process proceeds to step S180, and if there is a workpiece to be measured, the process returns to step S150.

  According to each embodiment of the present invention, even when the liquid level is difficult to measure by ultrasonic liquid level measurement, the liquid level can be measured in a non-contact manner by using laser light. That is, the liquid level height position can be measured until the laser irradiation light spreads, and the liquid level height in the submicron region can be measured. Further, since the irradiation path for the laser irradiation light only needs to be secured, it is not necessary to extend the liquid level height measurement path beyond the liquid injection port.

  Furthermore, even when a measurement passage is secured separately from the liquid injection port of the container, it may be about the diameter of the laser irradiation light and can be several mm or less, and the liquid level in the capillary It becomes suitable for the measurement etc.

  Further, as described above, according to each embodiment of the present invention, the liquid to be measured passes through the liquid even if partially inside the liquid, and then reflects off the reflecting material and returns to the light source side. It may be anything that comes, and even colored liquids may be measurable. Therefore, even if the liquid is a combustible material such as fuel, the measuring means does not have an electric substrate, so there is no fear of spark discharge, and the need for special means such as explosion proofing that is expensive is reduced.

  Also, since the resolution of height measurement is usually about half the wavelength of the laser beam used, it is theoretically possible to use a laser beam of 593 nm, for example, up to about 300 nm, but since a laser interferometer is used. Limited by the measurement accuracy of the laser interferometer. However, it is still possible to measure with an accuracy of about several μm. According to the present embodiment, the resolution can be improved to submicron or about several tens of nanometers by performing the interpolation process using the arithmetic means included in the laser interferometer.

  Therefore, it is possible to measure the height and surface tension of the droplet. In the above embodiment, the case where the wavelength of the laser beam is 593 nm is described with the yellow laser beam, but the wavelength of the laser beam is not limited to this, and various colors such as 405, 445, 460, 473, 532, 635, and 650 nm are used. Laser light can be used.

DESCRIPTION OF SYMBOLS 10 ... (Laser) light source, 12 ... Beam splitter (half mirror), 14 ... Fixed reflector, 16 ... Detector, 17, 18 ... Reflector, 18a-18d ... Virtual reflector position, 19 ... Housing, 20 ... Laser light (emitted light), 22 ... detection light (synthetic light), 24, 24x ... laser light (measurement light), 26 ... laser light (reference light), 30 ... (transparent) container, 30b ... (non-transparent) container , 32 ... opening (liquid injection port), 34 ... (measuring) liquid, 34 b ... flammable liquid, 38 ... mounting table, 40 ... liquid supply source, 42 ... liquid injection means, 45 ... liquid feeding, 50 ... liquid Surface height measuring device, 60 ... temperature sensor, 100 ... laser interference length measuring device, L ₀ ... reference liquid level height, L _D ... specified liquid level height, Lx ... liquid level height during measurement

Claims (7)

A liquid level measuring device for measuring a liquid level in a liquid container by a change from a reference height,
A laser interferometer having a laser light source, a beam splitter and a laser detector, and capable of emitting laser light;
A reflective material that reflects the laser light emitted from the laser interferometer in the lower part of the container,
The laser interferometer measures the reference optical path length and liquid level height of the laser light irradiated from the laser light source and reflected by the reflector when the liquid level in the container is at a reference height. The liquid surface is characterized in that the liquid surface height is obtained as a change from the reference height from the difference in optical path length during measurement and the refractive index of the liquid to be measured contained in the container during measurement. Height measuring device.   The liquid level measuring apparatus according to claim 1, wherein the container is a transparent container, and the reflecting material is disposed in proximity to the outer surface of the bottom of the transparent container.   2. The liquid level height measurement according to claim 1, wherein the container is an opaque container that does not transmit laser light, and the reflector is provided on the bottom surface of the container integrally or separately from the container. apparatus. Storage means for storing the refractive index in advance;
The refractive index data stored in advance is measured by the laser interferometer to inject the liquid from a reference height position of the container to a predetermined height position where the height is known. The liquid level height measuring apparatus according to claim 1 or 2.   The liquid level measuring device according to any one of claims 1 to 4, a liquid injecting unit for injecting a liquid into the container, and the liquid injecting unit based on a measurement value of the liquid level measuring device. A liquid injection apparatus comprising control means for controlling opening and closing of the injection path. A laser beam is irradiated from a laser interference length measuring device included in a liquid surface height measuring device to a reflecting material disposed at the bottom of a container into which a liquid is injected by a known height, and the reflected light reflected from the reflecting material is A step of measuring by the laser interferometer,
Similarly, the liquid is additionally injected into the container, and similarly, a laser beam is irradiated from a laser interference length measuring device to the reflecting material disposed at the bottom of the container, and the reflected light reflected from the reflecting material is reflected by the laser interference length measuring method. Steps that the instrument measures,
Calculating the difference in optical path length obtained by the difference between the two measurement results as the liquid level change amount in the container from the refractive index of the liquid;
The liquid level height measuring method using the liquid level height measuring apparatus characterized by including.   The liquid level height measuring method using the liquid level height measuring device according to claim 6, wherein the refractive index is obtained based on a detection value of a temperature sensor arranged in the vicinity of the container.