JPH0688783A - Liquid concentration meter - Google Patents

Abstract

PURPOSE:To obtain a liquid concentration meter which can prevent a reflection deposition film from being released and can retain a constant measurement accuracy. CONSTITUTION:The title meter is provide with a solid rod 14 consisting of a transparent resin, a detection part K which is formed at one edge part of the solid rod 14, a luminous part which is provided on the other end face of the solid rod 14 and applies light beams to the detection part K, and a light detection part which is provided on the other end face of the solid rod and detects the reflection light from the detection part. Then, a reflection deposition film 14a is formed on the end face of the solid rod and then a UV coat film 14b covering at least the reflection deposition film is formed on the reflection deposition film 14a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid rod made of a transparent resin, a detection portion formed at one end of the solid rod, and the detection portion provided at the other end surface of the solid rod. The present invention relates to a liquid densitometer having a light emitting section for emitting a light beam to a section, and a light detecting section provided on the other end surface of the solid rod for detecting reflected light from the detecting section.

[0002]

2. Description of the Related Art Conventionally, it is known that the concentration (volume%) of a liquid has a certain correlation with the refractive index of the liquid. A liquid concentration meter as shown in FIG. 7 is considered by utilizing this correlation.

In the figure, the solid rod 1 made of a transparent resin such as acrylic has a refractive index of n1. This solid rod 1
One end portion (front end side) of is used as a detection portion, and the end surface is formed in a hemispherical shape. Then, an aluminum reflection film 1a is formed on the end surface by vapor deposition or the like. On the other end side (base end side) of the solid rod 1, a light receiving and emitting integrated element 3 is provided by a holder 2. The light receiving / emitting integrated element 3 has a light emitting diode 3a as a light emitting portion whose light emitting surface abuts on the other end side end surface of the solid rod 1, and a light detecting portion whose light receiving surface abuts on the other end side end surface. The photodiode 3b is integrally provided.

The light emitting section drive circuit 4 is a circuit for driving the light emitting diode 3a, and the concentration measuring circuit 5 is a photodiode 3b.
This is a circuit for obtaining the concentration signal of the liquid to be measured 6 having a refractive index of n2 from the analog electric signal obtained from. Reference numeral 7 denotes a display unit for displaying the concentration signal output from the concentration measuring circuit 5.

Next, the operation of the above configuration will be described. The light emitting diode 3a is driven by the light emitting section drive circuit 4,
Emit a light beam. The light beam emitted from the light emitting diode 3a propagates in the solid rod 1 and is reflected by the reflective film 1a. This reflected beam is incident on the sensing portion A of the detector. At the sensing portion A, a part of the light beam is transmitted into the liquid to be measured 6, but the remaining light beam is totally reflected. Then, the totally reflected light beam is incident on the photodiode 3b.

The light beam incident on the photodiode 3b is converted into an analog current signal here. The analog current signal is converted into a concentration signal of the liquid to be measured 6 by the concentration measuring circuit 5 and displayed on the liquid crystal display unit 7.

According to the above arrangement, the light quantity of the light beam which causes total reflection is a function of the refractive index n2 of the liquid 6 to be measured.
On the other hand, the concentration of the measured liquid 6 and the refractive index n of the measured liquid 6
Since there is a certain correlation with 2, the concentration of the liquid 6 to be measured can be measured by detecting the light amount of the light beam that causes total reflection, that is, the light amount incident on the photodiode 3b.

[0008]

However, although the reflection film 1a of the solid rod 1 of the liquid concentration meter having the above-mentioned structure is a vapor deposition film of aluminum, the vapor deposition film of aluminum has poor fixability. In particular, when the reflective film 1a comes into contact with another object,
There is a problem that peeling easily occurs due to friction.

Further, such peeling of the reflective vapor deposition film 1a is
There is also a problem that the liquid densitometer cannot maintain a certain measurement accuracy.

The present invention has been made in view of the above problems, and an object thereof is to provide a liquid densitometer capable of preventing peeling of a vapor deposition film of a reflective film and maintaining a certain measurement accuracy.

[0011]

DISCLOSURE OF THE INVENTION The present invention which solves the above-mentioned problems includes a solid rod made of a transparent resin, a detecting portion formed at one end of the solid rod, and the other of the solid rods. In a liquid densitometer having a light emitting section which is provided on the end surface of the solid state and which emits a light beam to the detecting section, and a light detecting section which is provided on the other end surface of the solid rod and which detects reflected light from the detecting section, The reflective vapor deposition film provided on the detection unit and a UV coating film that covers at least the reflective vapor deposition film are provided.

[0012]

In the liquid densitometer of the present invention, since the UV coat film covers at least the reflective vapor deposition film, peeling of the reflective vapor deposition film is prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view showing an embodiment of the present invention. FIG. 2 is an enlarged view of the reflective film of the rod in FIG. 2, FIG. 2 is a side view showing an embodiment of the present invention, and FIG. 4 is a configuration diagram for explaining the attachment of the rod in FIG. 2, FIG. 5 is a sectional view taken along line VV in FIG. 4, and FIG. 6 is a block diagram for electrically explaining the liquid concentration sensor of the present embodiment. .

First, the structure of this embodiment will be described with reference to FIGS. Reference numeral 11 is a lower case, 12 is an upper case, and 13 is a battery holder, which constitute a case of the liquid concentration sensor of the present embodiment.

Reference numeral 14 is an acrylic resin (PMMA) rod provided at the tip of the lower case 11. This rod 1
Installation of No. 4 will be described with reference to FIGS. 4 and 5.

A through hole 11a is formed at the tip of the lower case 11.
, And two recesses 11b are provided on the inner wall surface. The tip of the upper case 12 is fitted into the inside of the lower case 11, and the projection 12 is engageable with the recess 11b.
a is formed. In addition, the convex portion 1 of the upper case 12
A cutout hole 12b is formed in the vicinity of 2a, and the projection 12
The vicinity of "a" is in a cantilever state so that it can be bent in the direction of arrow I in FIG.

Reference numeral 15 is a light emitting and receiving integrated element which is attached to the base end portion of the rod 14 and in which a light emitting diode 15a and a photo sensor 15b are integrally formed. The integrated light emitting and receiving element 15 is held in a stepped groove 12c provided at the tip of the upper case 12. Reference numeral 16 is an O-ring for waterproofing the lower case 11 and preventing the rod 14 from coming off.
17 is a liquid crystal display (LCD) that displays the concentration value of the liquid to be measured.
Is.

The tip portion of the rod 14 is used as the detecting portion K, and the end surface is formed in a hemispherical shape. Then, on the hemispherical end surface, a reflective film vapor deposition film 14a of aluminum,
A UV coat (coating of a resin adhesive having ultraviolet curability) film 14b that covers the reflective vapor deposition film 14a is formed, and the remaining portion is used as the sensing portion A.
In this embodiment, the UV coat film 14b covers the reflective vapor deposition film 14a, and further has a portion D which is in direct contact with the surface of the rod 14.

Next, the electrical construction of this embodiment will be described with reference to FIG. In the figure, reference numeral 16 is a subtraction circuit for adjusting the offset of the analog electric signal from the light emitting / receiving integrated element 15. Reference numeral 17 is an amplifier circuit for amplifying the offset-adjusted analog signal, 18 is a comparator for comparing the amplified analog signal with a predetermined value to generate a signal for liquid crystal display, 19 is generated by the comparator It is an LCD drive circuit for driving the liquid crystal display panel 17 using the signal.

Next, the operation of the above configuration will be described. The light emitting diode 15a is driven by a light emitting unit drive circuit (not shown) and emits a light beam. Light emitting diode 15a
The emitted light beam propagates in the rod 14 and is reflected by the reflective vapor deposition film 14a. This reflected beam is incident on the sensing portion A. At the sensing portion A, a part of the light beam is transmitted into the liquid to be measured, but the remaining light beam is totally reflected. Then, the totally reflected light beam is incident on the photo sensor 15b.

The light beam incident on the photo sensor 15b is converted into an analog current signal here. This analog current signal is converted into a density signal through the circuit described in FIG. 6 and displayed on the liquid crystal display panel 17.

According to the above construction, the acrylic resin rod 14 is used as the detecting portion. Therefore, it has good workability and is inexpensive.

The reflective vapor deposition film 14 for acrylic resin is also used.
Since a is covered with the UV coat film 14b, the reflective film vapor deposition film 14a does not peel off, and a certain measurement accuracy can be maintained. Further, in this embodiment, since the UV coating layer 14b is provided with the portion D which is in direct contact with the rod 14, the fixability of the UV coating layer 14b is improved and the peeling of the reflective vapor deposition film 14a can be further prevented.

The present invention is not limited to the above embodiment. In the above embodiment, the UV coating layer 14b is the rod 14
Although the portion D directly contacting with is provided, the portion D is not always necessary. Needless to say, the effect of the present invention can be obtained by covering at least the reflective vapor deposition film 14a without the portion D.

[0025]

As described above, according to the present invention, it is possible to realize a liquid concentration meter capable of preventing the vapor deposition film of a reflective film from peeling off and maintaining a certain measurement accuracy.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.
3 is an enlarged view of the reflective film of the rod in FIG.

FIG. 2 is a side view illustrating an embodiment of the present invention.

FIG. 3 is a plan configuration diagram in FIG. 2.

FIG. 4 is a configuration diagram illustrating attachment of the rod in FIG.

5 is a sectional view taken along line VV in FIG.

FIG. 6 is a block diagram for electrically explaining the liquid concentration sensor of the present embodiment.

FIG. 7 is a configuration diagram illustrating a conventional liquid concentration meter.

[Explanation of symbols]

 14 rod (solid rod) 14a reflective vapor deposition film 14b UV coating film 15a light emitting diode (light emitting part) 15b photo sensor (light detecting part) K detecting part

Claims (1)

[Claims] 1. A solid rod (14) made of transparent resin,
Detecting part (K) formed on one end of the solid rod (14) and light emission for emitting a light beam to the detecting part (K) provided on the other end face of the solid rod (14). Department (1
5a) and a light detector (15b) provided on the other end surface of the solid rod (14) and detecting the reflected light from the detector (K), the detector (K) ) Is a reflective vapor deposition film (14a), and a UV coat film (14b) that covers at least the reflective vapor deposition film (14a).