JP2784341B2 - Method and apparatus for measuring specific gravity and liquid volume of liquid - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring the specific gravity and the amount of a liquid, and more particularly to a method for measuring the specific gravity and the amount of a liquid so that maintenance can be simplified and maintenance costs can be greatly reduced. And its device.

[0002]

2. Description of the Related Art Urine volume and urine specific gravity are sometimes used as a means for measuring a person's health condition. The amount of urine can be obtained by reading a graduated scale on a container or by a liquid volume sensor using infrared rays or the like. The specific gravity of urine is obtained by measuring the weight in addition to the urine volume.

[0003] The specific gravity of urine is determined by using a float, a vibratory density meter,
A more accurate value can be obtained by measuring using a refractive index measuring device or the like based on the total reflection method. When using the above floats, graduated floats (buoys) are used as test liquids (urine).
And read the scale at the liquid level.

A vibration type densitometer is disclosed, for example, in Japanese Patent Publication No. 7-104.
As described in Japanese Patent Publication No. 247, a vibration cell composed of a U-shaped thin tube is provided, and the vibration frequency or the vibration period of the vibration cell when the test liquid (urine) is filled in the vibration cell is measured. The specific gravity of the test liquid (urine) is calculated from the frequency or frequency of the vibration cell.

[0005] Further, in a refractive index measuring apparatus based on the total reflection method, a prism is arranged on the lower surface of a measuring cell and transmitted through a prism from a light source as described in, for example, JP-A-6-273329. By irradiating the upper surface with light from a predetermined angle and detecting the distribution of reflected light from the upper surface of the prism, a critical angle at which reflection from a boundary surface between the upper surface of the prism and a sample (urine) in contact with the upper surface is obtained. The refractive index of the sample (urine) is calculated based on the critical angle. Since the refractive index of the sample (urine) increases and decreases corresponding to the specific gravity of the sample (urine), the specific gravity of the sample (urine) is further obtained from the refractive index.

[0006]

However, in the above-mentioned conventional method, the method of reading the graduations with human eyes is inaccurate and time-consuming.

Further, the density (specific gravity) is measured by a vibrating densitometer.
Or the method of calculating the specific gravity from the refractive index using a refractive index measuring device based on the total reflection method is accurate, but has a drawback that the device configuration becomes large and the cost increases.

Further, in any of the above methods, the weight, density, refractive index and the like are measured using another device or instrument after measuring the liquid volume with any instrument or device or before measuring the liquid volume. It is necessary to measure, and even if the apparatus is configured so that the above two steps can be performed continuously, basically, two apparatuses or instruments are required, so the apparatus configuration becomes large and the cost increases. Was.

The present invention has been proposed in view of the above-described circumstances, and relates to a method for determining the light receiving position of a parallel light beam transmitted through a test liquid, which relates the liquid specific gravity and the liquid amount to the refractive index and the liquid level. It is an object of the present invention to provide a method and an apparatus capable of measuring the specific gravity and the liquid volume of a test liquid only by measuring.

[0010]

The method for measuring the refractive index nD and the amount of a liquid according to the present invention employs the following means in order to achieve the above object.

First, the test liquid 2 forms a prism surface in the following manner. A parallel light beam is incident on the liquid surface L of the test liquid 2 at a predetermined incident angle α, and the parallel light beam is emitted from the output surface 2a of the test liquid 2 inclined with respect to the liquid surface L. When this outgoing light is imaged on the light receiving element 4 via the convex lens 5, as shown in FIG. 1, the image forming position at this time differs depending on the refractive index nD regardless of the liquid level height L. _{An image is formed at 0m} (m: a positive integer that divides a position depending on the refractive index). Thus, the refractive index nD of the test liquid is obtained.
However, as a prerequisite, it is necessary to obtain an image formation position in a reference liquid having a known refractive index nD.

Next, when the above-mentioned emitted light is received by the light receiving element 4 without passing through the convex lens 5, as shown in FIG. 2, the light receiving position in this case is the liquid if the refractive index of the test liquid is the same. There are different positions P _1n (n: positive integer dividing the position depending on the height) depending on the height L of the surface. by this,
The height of the test liquid will be required. However, even if the liquid level L is different, if the refractive index nD of the test liquid is different, light may be received at the same position. Therefore, the height of the test liquid also depends on the refractive index nD of the test liquid. Will do. Therefore,
As a prerequisite for obtaining the height, it is necessary to know the refractive index nD, and it is necessary to obtain a light receiving position at a reference liquid level under a specific refractive index nD.

An apparatus for realizing the above method is first provided with a light source 3 for emitting parallel rays, and a convex lens 5 is provided.
Can be taken in and out of the optical path. The light receiving element 4 is arranged at an image forming position of the convex lens 5.

In order to realize the above method, the test liquid must have a prism surface with respect to the incident light, that is, the output surface 2a is inclined with respect to the liquid surface L of the test liquid 2. Therefore, the sample liquid container 1 used here has a part of the bottom surface inclined, or the apparatus for realizing the above-described method inclines a container having a flat bottom surface, and thereby the light source 3 and the light receiving element 4 are inclined. Or the optical path from the light source 3 to the convex lens 5 must pass through the side peripheral surface of the container 1.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method according to the present invention applied to the method for measuring urine volume and specific gravity of urine and an embodiment of the apparatus of the present invention for carrying out the method will be described in detail with reference to the drawings. This will be described below.

As shown in the block diagram of FIG. 3, the apparatus for measuring the refractive index nD and the liquid amount according to the present invention includes a light source 3, which is mounted on a container 1 arranged at a predetermined position in the apparatus. A parallel light beam is incident on the liquid surface L of the test liquid 2 which is filled and forms a prism at a predetermined incident angle α. Further, the present invention includes a light receiving element 4 for receiving the parallel light beam transmitted from the light source 3 through the test liquid 2.

Although the configuration of the light source 3 is not particularly limited,
In this embodiment, a laser emitting device 3a is used as a light source, and two slit plates 3b and 3c arranged at an appropriate distance to secure parallelism of the light beams are arranged on the optical path.

The incident angle α of the parallel light beam emitted from the light source 3 to the liquid surface L of the test liquid 2 is set to be larger than zero, whereby the parallel light is refracted at the incident position of the liquid surface L to be irradiated. It can be made to enter the test solution 2. By setting the shape of the container 1 as described below, the prism surface can be constituted by the test liquid 2 filled in the container.

That is, in the example shown in FIG. 3, the central portion of the bottom surface 1a of the test liquid container 1 is formed in an inverted conical shape, and the peripheral wall 1b is placed on the base 6 of the apparatus. The emission surface 2a that coincides with the inverted conical surface at the center of the liquid crystal L is inclined with respect to the liquid surface L by a predetermined inclination angle θ (here, 45 °). As a result, if the refractive index nD is the same, as shown by the solid line (or broken line) in FIG. 1, even if the height of the liquid surface L changes, the output angle φ of the parallel light beam output from the output surface 2a is changed.
(Φ1, φ2) remain unchanged. A light receiving element 4 composed of, for example, a CCD is disposed below the container 1. A parallel light beam emitted from the light source 3 and transmitted through the test liquid 2 in the container 1 and the bottom center 1 a of the container 1 is emitted from the light emitting surface. When the light is emitted from 2a, it is refracted again and is incident on the light receiving element 4.

Further, a convex lens 5 is disposed between the container 1 and the light-receiving element 4 so as to be put in and out of the optical path of the parallel light beam. When the convex lens 5 is located on the optical path, The configuration is such that the parallel rays form an image on the light receiving element 4.

[0021] Thus, the imaging position on the light receiving element 4 via the convex lens 5 is not dependent on the liquid level of the test liquid, the position P _01, P depends only on the refractive index of the sample liquid It becomes ₀₂ .

As a result, since the positional relationship between the refractive index nD and the light receiving element 4 is in a predetermined relationship (see FIG. 5 described later), an image of the test liquid having the reference refractive index nD on the light receiving element 4 is formed. By knowing the position, the light receiving position P
The refractive index nD of the test liquid 2 can be calculated based on _0m (P ₀₁ , P ₀₂ ).

Next, if the convex lens 5 is removed from the optical path, assuming that the refractive index nD is the same, as shown in FIG. 2, according to the height ΔX of the liquid level L of the test liquid 2, As a result, the refraction position on the liquid surface L changes, and as a result, the light receiving position P _1n (for example, P ₁₁ , P ₁₂ ) on the light receiving element 4 changes. Therefore, the refractive index nD of the test liquid 2 obtained as described above
Then, the height of the liquid surface 2 of the test liquid 2 can be calculated based on the light receiving position P _1n on the light receiving element 4 when light is received without passing through the convex lens 5.

The relationship between the height of the liquid surface L and the position on the light receiving element 4 under a specific refractive index nD is as shown in FIG. 6, which will be described later. By _knowing the light receiving position P _1n at the height, the height of the test liquid can be calculated.

An arithmetic means (not shown) is provided for performing these calculations, and the liquid to be _measured is determined based on the light receiving position P _0m of the light receiving element 4 when the convex lens 5 is positioned on the optical path. 2 is calculated, and the specific gravity is calculated based on the calculated refractive index nD.

Further, the refractive index nD calculated as described above,
The height of the liquid surface L of the test liquid 2 is calculated based on the light receiving position P _1n of the light receiving element 4 when the convex lens 5 is positioned outside the optical path, and the calculated test _object L is added. The liquid amount is calculated based on the height of the liquid level L of the liquid 2.

Either the processing when the parallel light is incident on the light receiving element 4 via the convex lens 5 or the processing when the parallel light is incident on the light receiving element 4 without passing through the convex lens 5 is performed first. Whether or not to perform the treatment can be freely selected, but in order to shorten the processing time, first, based on the light receiving position P _0m of the light receiving element 4 when the parallel light transmitted through the test liquid 2 is received via the convex lens 5. To calculate the refractive index nD of the test liquid 2 and obtain the specific gravity of the test liquid based on the calculated refractive index nD. After that, the calculated refractive index nD and the convex lens 5
It is preferable to obtain the liquid amount based on the light receiving position _P1m of the light receiving element 4 when the light is received without passing through.

FIG. 4A shows a main part of still another embodiment of the apparatus of the present invention. In this embodiment, the convex lens 5 is fixed, and a light splitting means 10 for splitting a part of the parallel light beam emitted from the emission surface of the test liquid is provided. The light splitting means 10 is, for example, a half mirror 10h
The parallel light split by the half mirror 10h is received by the light receiving element 4a via the convex lens 5, and the other parallel light is directly incident on the light receiving element 4b. As a result, two light receiving positions required for the calculation can be obtained without rotating the convex lens 5.

In FIG. 4A, the light receiving element 4a and the light receiving element 4b are separated from each other, but as shown in FIG.
By using the mirror 10m, the common light receiving element 4 can be used.
It is also possible to use c.

As described above, according to the present invention, since the parallel light is transmitted through the test liquid constituting the prism and is received on the light receiving element 4, the transmitted light is transmitted onto the light receiving element 4 via the convex lens 5. The light receiving position when receiving light depends only on the refractive index, and the light receiving position when receiving light without passing through the convex lens 5 depends on the height and the refractive index of the test solution.

Thus, the refractive index, that is, the specific gravity, and the liquid level, that is, the amount of the test liquid, of the test liquid can be obtained by one apparatus, and the cost of the apparatus can be greatly reduced.

A sucrose solution valued by a high-precision refractometer is used as the test liquid 2, the incident angle α is set to 20 °, the refractive index nD and the address of the CCD as the light receiving element 4 (light receiving position). As a result, as shown in FIG. 5, it was found that a highly accurate measurement with a correlation error of nD = ± 0.0001 or less can be performed. In FIG. 5, the horizontal axis is CC
The address of D, and the vertical axis is the refractive index nD.

Further, a sucrose aqueous solution valued by a high-precision refractometer is used as the test liquid 2, the incident angle α is set to 20 °, the liquid level and the address of the CCD as the light receiving element 4 (light receiving position). As a result, as shown in FIG. 6, it was found that the liquid level height correlation error could be measured with high accuracy within ± 1 mm. In FIG. 6, the horizontal axis represents the CCD address, the vertical axis represents the liquid level (mm), and the refractive index nD = 1.
The relationship between the liquid level and the CCD address (light receiving position) is shown for four different liquids 33299, 1.33992, 1.34752, and 1.35637.

In the above embodiment, the container 1 is provided in the apparatus so that each subject can put his or her own urine in the container. In this case, the apparatus is provided with a washing device. After one measurement, the container needs to be washed.

Also, a specific container 1 is lent to each subject who collects the test liquid (urine) 2, and each person collects his / her own urine in the container 1 and transfers the container 1 The apparatus may be placed at a predetermined position on the apparatus. In this case, each person will wash his / her own container after the measurement is completed.

[0036]

As described above, according to the present invention, the refractive index, that is, the specific gravity of the test liquid, and the liquid surface height, that is, the amount of the test liquid, can be obtained by one apparatus, and the apparatus cost is greatly reduced. There is an effect that can be reduced.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a liquid specific gravity measurement of the present invention.

FIG. 2 is a principle diagram of the liquid amount measurement of the present invention.

FIG. 3 is a configuration diagram of an embodiment of the present invention.

FIG. 4 is an enlarged view of a main part of another embodiment of the present invention.

FIG. 5 shows a refractive index / CCD at an incident angle of 20 ° according to the present invention.
It is an address relationship diagram.

FIG. 6 shows the liquid level height CC at an incident angle of 20 ° according to the present invention.
It is a D address relationship diagram.

[Explanation of symbols]

2 test liquid 2a exit surface 3 the light source 4 light receiving element 5 convex α incident angle L liquid surface nD refractive index P _e, P _e1, P _e2 receiving position

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G01N 9/00-9/36 G01N 21/17-21/61 G01N 33/493 G01F 23/28

Claims (5)

(57) [Claims] When a parallel light beam is incident on a liquid surface of a test liquid constituting a prism surface at a predetermined incident angle, and a transmitted light from the test liquid is imaged on a light receiving element via a convex lens. The refractive index of the liquid is calculated based on the light receiving position of the liquid crystal, and the height of the liquid surface is calculated based on the light receiving position at which the light receiving element receives light with the convex lens removed and the calculated refractive index, A method for measuring a specific gravity and a liquid amount of a liquid, wherein a liquid specific gravity and a liquid amount are obtained from the refractive index and the height of the liquid surface. 2. A light source for irradiating a parallel light beam at a predetermined incident angle to a liquid surface of a test liquid constituting a prism surface, a light receiving element for receiving a transmitted light from the test liquid, and A convex lens that moves in and out of the optical path of the parallel light beam between the light receiving element and forms an image of the parallel light beam on the light receiving element when located on the parallel light ray, and positions the convex lens on the optical path. Calculating the refractive index of the liquid based on the light receiving position of the light receiving element at the time of, based on the calculated refractive index and the light receiving position of the light receiving element when the convex lens is positioned outside the optical path. Calculating the liquid surface height of the test liquid, and calculating the specific gravity and liquid amount of the liquid based on the refractive index and the liquid surface height of the base test liquid, measuring device 3. A light splitting means for fixing the convex lens and splitting a part of the parallel light beam emitted from the light emitting surface of the test liquid, wherein one of the parallel light beams split by the light splitting means is split. While entering the convex lens,
3. The measuring device according to claim 2, wherein the other parallel light beam is directly incident on the light receiving element. 4. The apparatus for measuring the specific gravity and liquid volume of a liquid according to claim 3, wherein the light receiving element for receiving the one parallel light beam and the light receiving element for receiving the other parallel light beam are common. 5. An apparatus according to claim 3, further comprising separate light receiving elements for receiving the one parallel light beam and the other parallel light beam, respectively.