JPH0629725Y2 - Liquid concentration meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention is directed to a detection unit having a reflection film formed at the tip and disposed in a liquid to be measured, and a light emission for emitting a light beam to the detection unit. And a photodetector that detects the reflected light at the detector, and the concentration of the liquid to be measured is utilized by utilizing the fact that the total reflection characteristic at the detector changes depending on the concentration value of the liquid to be measured. It relates to the required liquid concentration meter.

(Prior Art) It is conventionally known that the concentration (volume ratio) of a liquid and the refractive index of the liquid have a certain correlation. Utilizing this correlation, a liquid concentration meter as shown in FIG. 4 is known.

In the figure, 1 is a first optical fiber, one end of this optical fiber 1 is connected to an optical branching device 2, the clad part 1a is peeled off at the other end, and a core part 1b having a refractive index n _co is exposed. And is used as a detection unit. Exposed core part 1 of detection part
b is curved, and a reflection film 1c is formed at the tip. Reference numeral 3 denotes a light emitting portion in which a light emitting diode for emitting a light beam is built into the first optical fiber 1, and the second optical fiber 4
Is connected to the optical branching device 2. Reference numeral 5 denotes a photodetector unit having a built-in photosensor, which is connected to the optical branching device 2 via a third optical fiber 6. The core portion 1b, which is the detection portion of the first optical fiber 1, has a refractive index of _nm.
Is placed in the liquid 7 to be measured.

Next, the operation of the above configuration will be described. The light beam emitted from the light emitting portion 3 reaches the core portion 1b of the first optical fiber 1 via the second optical fiber 4 and the optical branching device 2. Here, since the propagation modes in the optical fiber 1 are multi-modes, a part of the light beam is transmitted to the measurement liquid, but the rest of the light beam is totally reflected. Then, the totally reflected light beam is reflected by the reflection film 1 c, the optical path is branched by the optical branching device 2, and is incident on the photosensor of the photodetector 5 via the third optical fiber 6.

According to the above configuration, the light amount of the light beam that causes total reflection is
Is a function of the refractive index n _m of the liquid to be measured 7. On the other hand, since the concentration of the liquid to be measured 7 and the refractive index of the liquid to be measured 7 have a certain correlation, the light amount of the light beam that causes total reflection, that is, the light amount incident on the photosensor in the photodetector unit 5. The concentration of the liquid 7 to be measured can be measured by detecting. Then, by arbitrarily selecting the curvature of the core portion 1b to be curved, it is possible to measure the concentrations of all the measured liquids 7 having a refractive index of n _m <n _co . Also,
With such a configuration, since no electric spark is generated and no influence of electromagnetic induction is exerted, it is possible to realize a liquid concentration meter suitable for a chemical plant or the like that requires safety and explosion proof properties.

(Problems to be Solved by the Invention) However, in the liquid concentration meter having the above configuration, when measuring the concentration of the liquid to be measured, the first optical fiber of the liquid concentration meter must be immersed in the liquid to be measured. Therefore, there is a problem that it takes time to measure.

Further, since an optical fiber is used as the detection unit, there is a problem that the structure is complicated and manufacturing is troublesome, and the detection unit is easily damaged during measurement or cleaning. Further, when the liquid to be measured is a drink, there is a problem that there is an unsanitary feeling.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid concentration meter that can measure the concentration of a liquid to be measured in a hygienic manner, and that is durable and easy to manufacture. To provide.

(Means for Solving the Problem) The present invention which solves the above-mentioned problems, has a liquid chamber to be measured which has an upper surface opened and which contains a liquid to be measured, and a liquid measuring chamber connected to the liquid chamber to be measured. The glass rod having a cylindrical shape protruding from the liquid measurement chamber into the liquid chamber to be measured is formed in a portion inside the liquid chamber to be measured, and the tip of the glass rod in the liquid chamber to be measured is formed into a conical shape, and A detection unit having a reflection film provided on the conical surface, a light emitting unit for emitting a light beam to an end face of the glass rod inside the liquid measurement chamber, and the light emitting unit integrally provided with the liquid of the glass rod. A photodetector that detects reflected light from the detection unit that is emitted from the end face in the measurement chamber, and a total reflection characteristic in the detection unit that is arranged in the liquid measurement chamber and changes depending on the concentration value of the liquid to be measured. Utilize the light It is characterized in that a concentration measuring section for obtaining the concentration of the liquid to be measured from the output signal of the detecting section and a display section for displaying the concentration data obtained by the concentration measuring section are provided.

(Operation) In the liquid concentration meter of the present invention, when the light beam is emitted from the light emitting section to the detection section in the measured liquid chamber while the measured liquid is contained in the measured liquid chamber, this light is emitted. The beam is reflected by the peripheral surface of the glass rod according to the concentration of the liquid to be measured, and then enters the photodetector. The concentration measuring unit utilizes the fact that the total reflection characteristic at the detecting unit changes depending on the concentration value of the liquid to be measured, obtains the concentration of the liquid to be measured from the output signal of the light detecting unit, and the display unit displays this concentration data. indicate.

(Example) Next, the Example of this invention is described using drawing. FIG. 1 is a side view showing an embodiment of the present invention, showing a cross section of FIG. 2, FIG. 2 is a side view showing an embodiment of the present invention, and FIG. 3 is shown in FIG. It is a figure which shows an upper surface.

In Figure 1 to Figure 3, 11 is the upper surface 11a is opened, the measured fluid chamber for accommodating the 12 (refractive index is an aqueous alcohol solution of n _m in this embodiment) the liquid to be measured, 13 to be measured fluid chamber It is a liquid measurement chamber that is connected to the bottom surface 11 b of 11.

The liquid measuring chamber 13 is provided with a glass rod 14 as a detecting portion protruding into the liquid chamber 11 to be measured. The glass rod 14 is made of quartz and is a solid cylindrical glass rod having a refractive index n _co . One end side (front end side) of the glass rod 14 is used as a detection portion, and the front end is formed in a conical shape, and the conical surface is coated with a reflective film 15. Reference numeral 16 denotes a light emitting diode 16a provided at the base end of the glass rod 14 as a light emitting portion for emitting a light beam into the glass rod 14, and a photo sensor 16b as a light detecting portion for detecting reflected light at the glass rod 14.
Is a light emitting and receiving integrated element integrally provided with. Reference numeral 17 denotes a photo sensor 16b using a light emitting section drive circuit for driving the light emitting diode 16a and the fact that the total reflection characteristic of the glass rod 14 changes depending on the concentration value of the liquid 12 to be measured.
This is a substrate provided with a concentration measuring circuit for converting an analog electric signal from the photosensor 16b into a concentration display signal in order to obtain the concentration of the liquid to be measured 12 from the reflected light detected by.

Reference numeral 18 denotes a power source for supplying electricity to the board 17, and 19 denotes the board 17.
LED that displays the concentration data obtained by the concentration measurement circuit section of
Is a display unit, and 20 is a switch.

A step portion 11c of the measured liquid chamber 11 is formed. The protector 21 having a plurality of through holes 21a can be placed on the stepped portion 11c. Reference numeral 11d is a protrusion for preventing the protector 21 from coming off at three places formed above the stepped portion 11c of the liquid chamber 11 to be measured.
Is provided with a notch hole 21b that can be inserted into the protrusion 11d.

Then, the protector 21 is placed on the stepped portion 11c in a state where the cutout hole 21b is inserted through the projection 11d, and is then rotated by a predetermined angle to prevent the protector 21 from being separated from the stepped portion 11c.

Reference numeral 22 is an O-ring for preventing the measured liquid 12 from entering the liquid measuring chamber 13, and 23 is an O-ring for fixing the O-ring 22.
It is a ring presser.

Next, the operation of the above configuration will be described. Light emitting and receiving integrated element 16
The light emitting diode 16a is driven by the light emitting section drive circuit of the substrate 17 and emits a light beam. The light beam emitted from the light emitting diode propagates in the glass rod 14 and is reflected by the reflection film 15. A part of the reflected light beam reaches the cylindrical surface of the glass rod 14. Since the light beam is multimode, a part of the light beam is transmitted to the liquid to be measured 12 (alcohol aqueous solution) on the cylindrical surface (sensing portion), but the remaining light beam is totally reflected. Then, the totally reflected light beam is received by the photosensor 16 of the light receiving / emitting integrated element 16.
incident on b.

The light beam incident on the photo sensor 16b is converted into an analog electric signal here. This analog electrical signal is
It is converted into a concentration display signal of the liquid to be measured 12 by the concentration measuring circuit of the substrate 17 and displayed on the display unit 19.

According to the above configuration, the light amount of the light beam that causes total reflection is
It is a function of the refractive index _{n m} of the alcohol aqueous solution 12. On the other hand, since the concentration of the alcohol aqueous solution 12 and the refractive index n _m have a certain correlation, the light amount of the light beam that causes total reflection, that is, the photosensor 16 of the light emitting / receiving integrated element 16.
The concentration of the alcohol aqueous solution 12 can be measured by detecting the amount of light incident on b. Then, by arbitrarily selecting the apex angle θ of the conical portion coated with the reflective film 15, it is possible to measure the concentration of all alcohol aqueous solutions 12 having a refractive index of n _m <n _co .

With such a configuration, the concentration of the liquid to be measured 12 can be measured only by pouring the liquid to be measured 12 into the liquid to be measured chamber 11, and it does not take time and effort for the measurement, which is hygienic.

Since the glass rod 14 is used as the detector as compared with the conventional example described above, it is more durable. Further, since the light emitting / receiving integrated element 16 in which the light emitting diode 16a as the light emitting portion and the photo sensor 16b as the light detecting portion are integrally provided is provided on the end surface of the glass rod 14, the structure is simplified.

Further, since one end side of the cylindrical glass rod 14 is formed in a conical shape and the reflecting film 15 is provided on this conical surface, the light beam emitted from the light emitting diode 16a should be reflected by the reflecting film 15 in the conical portion. The beam reflected by the reflection film 15 becomes a wide beam (which has a fan shape when viewed from the axial direction of the glass rod 14) and becomes the circumferential surface of the glass rod 14 (sensing portion A). Incident on. Therefore, the light receiving area of the sensing unit A is larger than that in the case where the reflective film 15 is flat, and the measurement error when the surface of the sensing unit A has a minute scratch can be reduced. Therefore, the finishing of the surface of the sensing unit A does not have to be nervous, and the manufacturing is easy. Also, the glass rod 14
Has a cylindrical shape and one end side thereof is formed into a conical shape, so that the light emitting diode 16a and the photo sensor 16b (which are integrally configured as described above) are arranged so as to face the end surface of the glass rod 14 on the other end side. Is the glass rod 1
Since the measurement sensitivity hardly changes even when it is rotated about the central axis of 4, it does not need to be nervous at the time of positioning at the time of assembling to the glass rod 14, and the manufacturing is easy from this point as well.

The present invention is not limited to the above embodiment. For example,
In the above embodiment, the present invention has been described as an embodiment using an alcohol concentration meter, but it goes without saying that it can be applied to other liquids. The display unit 19 is not limited to the LED, and may be an LCD or the like. Further, although the measurement liquid chamber 13 is provided on the bottom surface side of the measurement liquid chamber 11, it may be provided on the side surface.

(Effects of the Invention) As described above, according to the present invention, the concentration of the liquid to be measured can be measured simply by putting the liquid to be measured in the liquid chamber to be measured and looking at the display section. Moreover, the concentration of the liquid to be measured can be easily measured, and the tip of the portion of the cylindrical glass rod protruding from the liquid measuring chamber into the liquid measuring chamber is conical. Since the detector is formed by providing the reflecting film on the conical surface, the light emitting portion and the light detecting portion are integrally provided so as to face the end surface on the other end side of the glass rod.
It is possible to realize a liquid concentration meter that is durable, has a simple structure, and is easy to manufacture.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.
FIG. 2 is a sectional view of the drawing, FIG. 2 is a side view showing an embodiment of the present invention, FIG. 3 is a top view of FIG. 2, and FIG.
The figure is a block diagram for explaining a conventional example. 1 ... 1st optical fiber, 2 ... Optical branching device 3 ... Light emitting part, 4 ... 2nd optical fiber 5 ... Photodetection part, 6 ... 3rd optical fiber 7, 12 ... Target Liquid to be measured, 11 ... Liquid chamber to be measured 13 ... Liquid measuring chamber, 14 ... Glass rod 15 ... Reflective film 16 ... Receiving / emitting integrated element, 17 ... Substrate 19 ... Display, 20 ... Switch 21 ...... Protector, 22 …… O-ring

Claims (1)

[Scope of utility model registration request] 1. A measured liquid chamber having an open upper surface for containing a measured liquid, a liquid measuring chamber connected to the measured liquid chamber, and protruding from the liquid measuring chamber into the measured liquid chamber. A detection unit having a cylindrical glass rod formed in a portion inside the liquid chamber to be measured, the tip of the glass rod inside the liquid chamber to be measured is formed in a conical shape, and a reflection film is provided on the conical surface. A light emitting unit that emits a light beam on the end face of the glass rod inside the liquid measurement chamber; and a reflection on the detection unit that is provided integrally with the light emitting unit and that emits from the end face of the glass rod inside the liquid measurement chamber. A light detection unit that detects light, and the fact that the total reflection characteristic of the detection unit, which is arranged in the liquid measurement chamber, changes depending on the concentration value of the liquid to be measured, is used to detect the output signal from the light detection unit. Obtain the concentration of the measurement liquid That concentration measuring unit and the liquid concentration meter, characterized by comprising a display unit for density data display determined by the concentration measuring unit.