JPS61159138A - Densitometer - Google Patents

Abstract

PURPOSE:To prevent the quantity of transmitted light from decreasing and having variance and to eliminate measurement errors by providing a floating plate which is movable for adjustment to the light collecting surface of a prism, providing a weight which places a vertical load on the light collecting surface, and spreading uniformly and detecting sample liquid. CONSTITUTION:A light beam transmitted through the sample liquid is diffracted by an angle corresponding to the concentration of the sample liquid and projected from the prism and the angle of the projection light is detected to measure the concentration of the sample liquid. The floating plate 23 is provided inside a light shield cover 21 and a light collecting plate 24 is fitted in its center. The floating plate 23 is movable to and away from the light collecting surface of the prism for adjustment and the weight 29 is provided on its top surface while straddling the light shield plate 24. The reverse surface of the light collecting plate 24 is arranged while superposed upon the light collecting surface of the prism and the sample liquid is interposed between them. Thus, the floating plate 23 is movable for adjustment and the weight 29 is provided on its top surface to apply place a vertical load on the sample liquid uniformly by the cooperation between the both. Consequently, the sample liquid is spread uniformly and thinly between the prism and light collecting plate 24 to uniform the quantity of transmitted light.

Description

[Detailed description of the invention] Industrial applications TECHNICAL FIELD The present invention relates to a concentration meter that is most suitable for a sugar content meter and the like.

PRIOR ART AND THEIR PROBLEMS Conventionally, eyepiece type saccharimeters that utilize a prism have been known as saccharimeters for measuring sugar concentration.

As shown in FIG. 1A, this saccharimeter has a prism 1 whose first surface is a light-collecting surface 2, whose second surface is a colored reflective surface 3, and whose third surface is a light-emitting surface 4. Apply it to the entire surface and apply the test solution 5.
The transmitted light beam is passed through the prism l, refracted at an angle according to the concentration of the test solution, and emitted from the light emitting surface 4. The light P2 emitted without being reflected is passed through the gauge plate 6, and the density is read at the position where the boundary line P between the colored light and the white light crosses the scale 7 of the gauge plate 6 (see Figure 1B). .

However, with this saccharimeter, the boundary line between bright and dark is examined with one eye through a small eyepiece window, which makes it very difficult to see, and the boundary line causes fluctuations in the field of view depending on the eyepiece posture, angle, etc. There are disadvantages such as the presence of odd color areas that do not belong to any of the areas, resulting in blurring, and the difficulty of grasping the exact boundaries.
In addition to being prone to false detections and being difficult to use, the test liquid applied to the prism's light collection surface becomes uneven, making the amount of transmitted light uneven and causing the test liquid to become uneven. It is too thick, and the amount of transmitted light is significantly reduced, resulting in measurement errors and the like, which has the disadvantage that highly reliable concentration detection ability cannot be expected. These drawbacks become more noticeable when the viscosity of the test liquid is high.

Purpose of the Invention The present invention was provided in order to eliminate the above-mentioned problems, and even when the viscosity of the test liquid is high, it may adhere thickly to the prism surface, or thick and thin spots may form, causing damage to the optical system. This prevents the amount of light incident on the prism from decreasing, and ensures that the test liquid always forms a thin layer with a uniform thickness on the light-collecting surface of the prism, thereby preventing the amount of transmitted light from decreasing and dispersing, and reducing the occurrence of measurement errors, etc. The object of the present invention is to provide a densitometer that effectively solves the problem.

Means for Solving the Problems In order to solve the above problems, the present invention passes the transmitted light beam of the test liquid through a prism, refracts it at an angle corresponding to the concentration of the test liquid and emits it, and detects the angle of the emitted light. In a densitometer that measures the concentration of a test liquid, a movable plate is provided that can be adjusted relative to the prism light-collecting surface, a light-collecting plate that overlaps the prism light-collecting surface is provided on the movable plate, and the prism is A weight is provided to apply a vertical load to the light-collecting surface of the prism, so that the sample liquid is always uniformly spread on the light-collecting surface of the prism and used for detection, regardless of the type of test liquid and the amount supplied.

That is, according to the present invention, the floating plate that is adjustable with respect to the prism surface is provided with a weight that applies a vertical load to the prism surface, so that the weight that applies a vertical load to the prism surface is formed between the lighting surface of the prism and the lighting plate. An average vertical load is applied to the test liquid layer,
The test liquid layer can be made evenly thinner, and measurement accuracy can be improved.

Furthermore, since the layer of test liquid spreads over the entire light-collecting surface of the prism, concentration can be measured with a small amount of test liquid.

EXAMPLES The present invention will be explained below based on illustrated examples. 2 to 4 show the principle mechanism and concentration measurement method of a concentration meter to which the present invention is applied.

The prism 10 has a first surface as a light-collecting surface 12 and a second surface as a light-absorbing surface 13. In FIG. 1, the second surface of the prism l is a colored reflective surface, but in this embodiment, the second surface is a light absorption surface 13, and the light transmitted through the test liquid reaching this surface is prevented from being emitted as much as possible. The surface is black so that it does not reflect light to eliminate disturbance factors.

Further, the third surface is used as a light emitting surface 14, and the transmitted light of the test liquid that does not reach the light absorbing surface 13 is emitted for concentration detection.

A lens 15 for optical imaging is disposed facing the light exit surface 14 of the prism 10, and an image sensor 16 is disposed at the focal plane F of the lens 15.

Light exit surface 14. The optical imaging lens 15 and the image sensor 16 are arranged to face each other within the light-shielding cylinder 18 in order to eliminate disturbance factors.

The image sensor 16 has a large number of photoconversion elements (semiconductors) 17 such as phototransistors arranged in a row and is packaged with a circuit IC that converts light into an electrical signal, and the surface on which the photoelectric conversion elements are arranged in tandem is used as a lighting window.

The adoption of the image sensor 16 is based on the phenomenon that the transmitted light of the test liquid emitted from the prism IO is approximately proportional to the concentration, and the emission angle of its critical light ray changes.

That is, when the test liquid 19 is applied to the light-collecting surface 12 of the prism IO and covered with the light-collecting plate 24 as shown in FIG.
The incident light is diffusely reflected on the glass surface in contact with the test liquid, becoming light rays in all directions, but it passes through the test liquid. Due to the critical angle determined by the refractive index of the prism lO and the refractive index of the prism lO, it does not exist at a critical angle of 7 or more.

For convenience, the ray of light having the critical angle γ will be referred to as the critical ray Ql.

This critical ray Q1 is further refracted by the light exit surface 14 of the prism 10 and exits at an angle θ.

Therefore, the light rays emitted from the prism 10 exist only at angles less than or equal to θ, and there are no light rays emitted at angles greater than 0, for example, the light rays X1.

The critical ray Q1 is at an angle θ proportional to the concentration of the test solution.
and enters the lens 15 for optical imaging,
Through this, the light is received by the image sensor 16 arranged at the focal plane F of the lens 15.

In FIG. 4, Ql indicates the critical ray that exits the prism 10 with an elevation angle of the angle θ and enters the lens 15, and the ray that passes through the lens 15 and is received by the image sensor 16 is the critical ray as described above. Below the exit angle of the light ray Ql, and below the position of the image formed by the critical ray Q1, there are rays of each angle, for example, the ray Q2. Q3 forms an image and becomes brighter.

As a result, the position where the critical light beam Q1 is received is defined as the boundary S between bright and dark, the section below S is defined as a bright section Wl, and the section above S is defined as a dark section W2. That is, the boundary S, the dark zone W2, and the bright zone W1 move up and down in proportion to the concentration of the test solution for the reason described above, and the photoelectric conversion element 17 in the open bright zone Wl is irradiated.

As a result, a certain number of photoelectric conversion elements 17 within the interval corresponding to the concentration of the test solution respond, and each outputs an electric signal (voltage).

This electric signal is applied to the data conversion circuit AI to convert it into a digital or analog signal representing the concentration value, and this is displayed on the display A.
2, and the concentration of the test solution 19 is clearly displayed in digital or analog form.

As shown in Figures 5 to 10, the prism 10° lens 1
5, image sensor 16, data conversion circuit A1. The display device A2 is housed in the densitometer container 20, and the prism 10 is fixed so that its light receiving surface 12 is located on the open surface 20a of the densitometer container 20.

21 is a light-shielding cover for the open surface 20a, and the light-shielding cover 21
has one end pivotally connected to the concentration meter container by a hinge 22, and is configured to be able to open and close with respect to the open surface 20a.

A floating plate 23 is provided inside the light shielding cover 21. A lighting plate 24 is attached to the center of the floating plate 23, and a stepped portion 25a is provided in the middle on the upper surface of the floating plate 23 on both sides of the lighting plate 24.
A guide column 26 hanging vertically from the inner surface of the light-shielding cover 21 is loosely inserted into the tube section 25, and a washer is fixed to the lower end of the guide column 26 with a screw 28, etc. A flange 27 that abuts against the portion 25a is formed to prevent it from coming off.

Therefore, the movable plate 23 is made movable in the left-right direction or torsional direction within the gap between the guide column 26 and the cylindrical portion 25 into which it is loosely inserted, and the lower surface of the light-shielding cover 21 and the upper end of the cylindrical portion 25 and the cylindrical portion are It is suspended between the step portion 25a of No. 25 and the washer so as to be freely movable in the vertical direction.

That is, in the present invention, the movable plate 23 can be adjusted within the above-mentioned range with respect to the light receiving surface 12 of the prism.

Further, a weight 29 is provided on the upper surface of the floating plate 23 so as to straddle the lighting plate 24.

Further, the lower surface of the lighting plate 24 is the lighting surface 1 of the prism lO.
2, and the test liquid 19 is placed between them.
The configuration is such that it intervenes.

As described above, the floating plate 23 can be adjusted, and the weight 29 is provided on the upper surface of the floating plate 23, and the weight 29 works together to apply an average vertical load to the test liquid 19. Therefore, the test liquid 19 is spread evenly and thinly between the prism 10 and the lighting plate 24, thereby making the amount of transmitted light uniform.

In addition, in this embodiment, the floating plate 2 surrounded by the light shielding cover 21
A light source lamp 33 (LED) is installed on the upper surface of the lighting plate 24, facing the light incident surface 24b at one end of the lighting plate, and the light source lamp is oriented so that the transmitted light can enter the lighting plate 24 at the best angle. It is installed in an adjustable manner.

This example will be explained based on FIGS. 8 to 10. *Moving plate 23
On the upper surface, semicircular arc-shaped guide pieces 30a, 30a are arranged to stand in front of the light incident surface 24b at one end of the lighting plate 24 so as to be concentric with each other.

On the other hand, a lamp holder is constituted by rotating pieces 31a, 31a having semicircular arc-shaped side surfaces and a lamp holding piece 31b having an insertion hole 32 for a light source lamp 33 in the center thereof, and the above-mentioned lamps are provided on both sides of the lamp holding piece 31b. Rotating pieces 31a, 31a are attached, and handles 31c, 31c protruding from one side of the attached surface are inserted into holes 31d, 31cl bored on the other side, and are assembled so as to be rotatable with respect to each other.

The lamp holder assembled in this way has a guide piece 30a.
, 30a, and the light source lamp 33 is inserted into the hole 32.

Thus, the lamp holder is rotated through the rotating pieces 31a, 31a,
The guide pieces 30a can be rotated between the guide pieces 30a (in the direction of the arrow in FIG. 9), or the lamp holding piece 3tb can be rotated between the guide pieces 30a and 30a.
, 31a and downward (in the direction of the arrow in FIG. 8). Therefore, after determining the best angle for the light source lamp 33,
The components of the lamp holder, the lamp holder, and the guide pieces 30a, 30a are fixed by gluing or the like.

Further, a half-bead-pyramidal light guiding portion 24a is formed on the upper surface of the lighting plate 24, and the light source lamp 33 is directly opposed to the end surface of the light guiding portion 24a. In this case, the light incident surface 24b and the lamp 33 are tilted so that the light enters at a constant angle with respect to the prism light receiving surface.

As described above, the light from the light source lamp 33 enters the light guide section 24a through the incident surface 24b, is further guided by the light guide section 24a, and enters the test liquid 19 at the adopted angle. Depending on the implementation, the lighting plate 24 may have a rectangular parallelepiped shape as a whole.

As described above, the prism lighting surface is covered with the light-shielding cover 1, and the light source lamp 33 and the lighting plate 24 are integrally arranged inside the light-shielding cover 1, and overlap the prism lighting surface when the cover 1 is closed.

Therefore, it is possible to perform measurements under conditions where natural light cannot be secured, and the disturbance factors that occur when using natural light are removed.
Enables stable measurement under constant conditions.

Further, the measurement results made within the densitometer container 20 are displayed on a display window 34 provided on the top surface of the densitometer container 20.

It can be observed outside.

Effects of the Invention As detailed above, the present invention allows the transmitted light beam of the test liquid to pass through a prism, refract it at an angle corresponding to the concentration of the test liquid, and emit it, and measure the concentration of the test liquid by detecting the angle of the emitted light. This is a densitometer that performs measurements, and unlike those in which the test liquid is simply applied to the prism light-collecting surface or a ground glass is placed on the liquid surface for measurement, the test liquid is applied to the prism light-collecting surface. An adjustable floating plate is provided, a lighting plate that overlaps the prism lighting surface is provided on the floating plate, and a weight is provided on the floating plate to apply a vertical load to the prism lighting surface, so that the synergistic effect of the floating plate and the weight is achieved. This action applies an average load to the test liquid and spreads it uniformly along the prism lighting surface to form a uniform H-like test liquid layer. At the same time, the test liquid layer is appropriately thin and leveled to allow the amount of transmitted light to be transmitted satisfactorily without attenuation.

Furthermore, even when the viscosity of the test liquid is high, the conventional problem of thick adhesion or thick/thin spots that result in inadequate light transmission or insufficient light intensity is effectively eliminated, making it stable and highly reliable. It became possible to measure the concentration of

[Brief explanation of drawings]

Figure 1A is a side view schematically illustrating the principle of a conventional saccharimeter using a prism and a light beam transmitted through a test solution, and Figure 1B is a front view schematically illustrating the indication state of the saccharimeter at the eyepiece of the same saccharimeter. , Figure 2 and subsequent figures show embodiments of the densitometer according to the present invention, and Figure 2 is a side view schematically showing the principle operating mechanism of the densitometer with the arrangement of the prism, lens, and image sensor. The figure is a side view explaining the state of the test liquid transmitted light in the same prism as above.
The figure is a side view illustrating how the light beam transmitted through the prism is received by the image sensor through the lens, FIG. FIG. 7 is a partially cutaway perspective view showing the internal structure; FIG. 7 is a cross-sectional view showing the floating mechanism of the floating plate and light shielding cover in the above densitometer; and FIG. 8 is a sectional view showing the internal mechanism of the light shielding cover in the same densitometer. A sectional view, FIG. 9 is a plan view showing the arrangement of a light source lamp and a daylight plate in the above densitometer, and FIG. 10 is an exploded perspective view of the lamp holder. DESCRIPTION OF SYMBOLS 10... Prism, 12... Light-collecting surface, 13... Light-absorbing surface, 14... Light-emitting surface, 15... Lens, 16
...image sensor, 17...light conversion element, 19.
... Test liquid, 20... Concentration meter container, 20a... Open surface, 21... Light shielding cover, 22... Hinge, 23...
・Floating plate, 24... Lighting plate, 25... Tube, 26...
・Guide pillar, 27... Tsuba, 29... Weight, 30a,
30a... Lamp holder guide piece, 31a...
- Rotating piece, 31b...Lamp holding piece, 33...Light source lamp.

Claims (1)

[Claims] A densitometer that measures the concentration of the test solution by passing the transmitted light beam of the test solution through a prism and refracting it at an angle corresponding to the test solution concentration, and detecting the angle of the emitted light.The prism can be adjusted with respect to the lighting surface. 1. A densitometer comprising: a floating plate, a light-lighting plate overlapping a prism light-lighting surface, and a weight for applying a vertical load to the prism light-lighting surface.