JPH0220672Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] The present invention is a device for detecting liquid flow in a viscometer under high temperature using a viscosity tube having a thin tube section at the lower end of a long glass tube. This is related.

[Conventional technology]

Normally, in a capillary flow-down viscometer, as shown in Fig. 1, the center of a long glass tube is bulged out in a daruma shape to create an upper chamber B and a lower chamber A, and a capillary tube part 1 is provided at the lowermost end. The formed viscosity tube 2 and a first pair of light guides 4 and 5 for liquid detection, which are arranged to face each other on the outer peripheral wall of the constriction part 3 between the upper chamber B and the lower chamber A. , and a second pair of light guides 6 and 7 for liquid detection, which are arranged to face each other on the outer circumferential wall between the lower chamber A and the thin tube part 1.

The above-mentioned viscometer receives light L 1 _and light from the terminals of one of the guides 4 and 6 of the first and second pair of light guides, respectively.
L ₂ is irradiated so that the lights L ₁ and L ₂ pass through the transparent viscosity tube 2 as passing lights L' ₁ and L' ₂ , respectively, and the passing lights L' ₁ and L' ₂ are guided through the other guides 5 and 7, respectively, and detected as transmitted light L'' ₁ and L'' ₂ by a photodetector such as a phototransistor.

Thus, for example, the liquid F to be measured
is filled into the viscosity tube 2, and the upper and lower chambers B and A are filled with the liquid F. Next, the upper part of the viscosity tube 2 is opened, and the liquid F slowly flows down from the thin tube part 1.
The liquid level f of the liquid F in the lower chamber A is measured at the time when the liquid level f crosses the first passing light L' ₁ and the time when it crosses the second passing light L' ₂ . This is to measure the time it takes for the liquid to flow out through the thin tube section 1.

However, each light guide 4, 5, 6, 7
If used for a long time under high temperature, it will deteriorate and the light L ₁ ,
The transmittance of L ₂ becomes poor, and the other light guide 5, 7
The transmitted light L″ ₁ and L″ ₂ emitted from the guides also became weaker, resulting in a disadvantage that the light transmittance deteriorated significantly compared to when each guide 4, 5, 6, and 7 was initially used. .

In other words, the liquid level f of the liquid F is detected by guiding the lights L ₁ and L ₂ from the light source 11 such as a lamp to the viscosity tube 2 through one of the light guides 4 and 6, respectively. The passing lights L' ₁ and L' ₂ passing through are further guided to the respective phototransistors 12 and 13 by the other light guides 5 and 7, respectively.

Thus, if there is no liquid F in the viscosity tube 2,
The passing lights L' ₁ and L' ₂ are scattered, and if there is a liquid F,
The passing lights L' ₁ and L' ₂ are scattered, and if there is a liquid F,
The transmitted lights L' ₁ and L' ₂ are condensed, and the amount of each transmitted light L'' ₁ and L'' ₂ changes depending on the presence or absence of the liquid F. As a result, the presence or absence of the liquid F, that is, the passage of the liquid surface, can be determined from this change in the amount of light.

However, when each of the light guides 4 to 7 is new, as shown in FIG. 2, the amount of light Q of each transmitted light L'' ₁ and L'' ₂ is large, and for example, the value qa of the amount of light when there is no liquid F is also high. . Moreover, when liquid F is present, the value qb becomes even higher. On the other hand, each light guide 4~
7 is used for a long time, the light quantity Q of the transmitted light L″ ₁ , L″ ₂ , both the value qc when there is no liquid F and the value qd when there is liquid F, becomes the corresponding value qa and qb. Compare,
The problem was that both values were low.

That is, in FIG. 2, the ratio of the difference △E ₁ between the values qb and qa and the difference △E ₂ between the values qd and qc is △E ₁ /△
E ₂ had the disadvantage that the difference between new and long-term used products varied widely, ranging from 500 to 1000.

In this way, when the light guides 4 to 7 are used for a long time, the above-mentioned △E ₁ / △E ₂ changes greatly from 500 to 1000, so when the light guide is new, it is necessary to If the amplification ratios of the amplifiers are matched, as the light guide deteriorates after long-term use, the amplification ratios of the amplifiers will need to be adjusted again, which has the disadvantage of making the device extremely complicated to use. .

In addition, if the amplification rate of the amplifier is adjusted when the light guide deteriorates after long-term use, the high sensitivity of the amplifier when the light guide is new will increase the frequency of equipment malfunctions during measurement, resulting in production When used in a process, the product quality deteriorates.

[Purpose of invention]

The present invention has been devised for the purpose of solving the above-mentioned problems.

In Figure 2, the light guide is new and the values qa,
The fact that the state represented by qb and the difference △E ₁ becomes obsolete and becomes that represented by the values qc, qd and the difference △E ₂ means that the intensifier input based on the received light This is equivalent if you consider changing the input signal DC ₁ to DC ₂ and the output of the amplifier.

In other words, in Figure 2, the difference in value △E ₁ in the case of a new product and the DC bias DC ₁ corresponding to the value qa
The ratio between △E ₁ /DC ₁ and the value difference △E ₂ for long-term used products and the ratio of DC bias DC ₂ to the value qc △
E ₂ /DC ₂ is almost always constant. Utilizing this fact, as the difference becomes smaller like △E ₂ , the amplification rate of the amplification device is increased, and the liquid level f of the liquid F flowing down the thin tube 1 is adjusted to reduce the deterioration of each guide 4 to 7. The aim is to accurately detect the presence or absence of

[Structure of the idea]

The present invention provides at least two viscosity tubes disposed opposite to each other on the outer circumferential wall of the viscosity tube 2 of the capillary flow-down type viscometer.
pairs of light guides, namely a first pair of light guides 4, 5 and a second pair of light guides 6, 7 for liquid detection;
, photodetectors such as phototransistors 12 and 13 that receive the light passing through one light guide 4 and 6 via the other light guide 5 and 7, and an electric field effect that mainly attenuates the signal from this photodetector. transistor
Attenuator AT and attenuator such as FET
It consists of an amplifier A ₁ including a transistor Q ₁ and the like arranged after the AT, and a comparison amplifier A ₂ connected after _the amplifier A ₁ . While applying the reference voltage Es via the switch SW,
This flow detection device for a capillary flow-down type viscometer is characterized in that the output of the amplifier _A2 is connected to the attenuator AT, and the degree of attenuation of this attenuator is made variable.

[Explanation of Examples]

First, an embodiment will be described based on FIGS. 3 and 4. For example, phototransistor 12
When the transmitted light L'' ₁ hits the phototransistor 12, a signal a is outputted from the phototransistor _12. In FIG. If indicated by T, it will be as shown in Figure 4a.
In this waveform of the signal a, the downward protrusion occurs when the liquid surface f and the passing light L' ₁ overlap, and this is because the amount of light naturally decreases. Furthermore, what is clear from a in Figure 4 is that
In the presence of liquid F, the transmitted light L' ₁ converges, and the transmitted light L'' suddenly becomes stronger.

A ₁ is an amplifier whose gain can be changed, and this amplifier A ₁ is arranged after the phototransistor 12 . The output signal b of this variable gain amplifier _A1 is
The result is as shown in FIG. 4b.

A ₂ is a comparison amplifier, and the comparison amplifier A ₂ is connected after the variable gain amplifier A _1. The output of the amplifier A ₁ is input to one input terminal, and the output is Output to variable gain amplifier _A1 . Es is a reference voltage and is input to the other input terminal of the comparator amplifier _A2 .
Thus, the comparison amplifier _A2 outputs an output signal for gain correction. The output signal of the comparison amplifier _A2 is fed back to the variable gain amplifier _A1 .
As will be described later in the explanation of FIG. 5, this feedback makes the reference level of the output signal b of the variable gain amplifier _A1 , that is, the output level when there is no liquid F in the viscosity tube 2, equal to the reference voltage Es. becomes possible.

_A3 is a differential amplifier, which is connected after the variable gain amplifier _A1 and outputs a signal as shown in FIG. 4c. Note that this differential amplifier _A3 is
Extract the AC component of signal b.

G ₁ is a direction gate circuit, and this gate circuit is
It is arranged after the differential amplifier A ₃ and rectifies the waveform of the signal c to produce only the signal d in the necessary direction.

FF is a memory such as a flip-flop, and this memory is connected after the direction gate circuit _G1 .
The signal d is held temporarily.

Note that FIG. 5 is a concrete electronic circuit based on the block diagram of FIG. 3, and the reference signals correspond to those in FIG. 3. The variable gain amplifier _A1 in the figure is
Field effect transistor for attenuator AT
It consists of a FET, a transistor Q ₁ for increasing the width, and others.

To summarize the operation in Fig. 5, in the case of △E ₁ /DC ₁ in Fig. 2, the attenuation of the field effect transistor FET is increased, and in the case of △E ₂ /DC ₂ in Fig. 2, the attenuation amount of the attenuator AT is increased. Reduce the amount of attenuation and amplify it with transistor _Q1 .

In the case of Fig. 5, the output b of variable gain amplifier _A1 is:
It is connected to a comparison amplifier A ₂ , and the output of the comparison amplifier A ₂ is connected to a field effect transistor FET for the attenuator AT of the variable gain amplifier A ₁ to form a closed loop.

Now, in Fig. 5, when the switch SW is turned on, the reference voltage Es is connected to the comparator amplifier _A2 ,
The field effect transistor FET operates so that the output b of the variable gain amplifier _A1 becomes equal to the reference voltage Es.

When the switch SW is turned off, capacitor C ₃ stores a charge with a voltage equal to the reference voltage Es, so the amplification degree of variable gain amplifier A ₁ is determined by the voltage applied to capacitor C ₃ . until it changes,
It is held at the value when the switch SW is on.

In other words, if the reference voltage Es is determined so that the amplification degree of the variable gain amplifier A ₁ is required at the time when the light guide deteriorates, the light guide can be used for a long time from when it is new. This means that stable measurements can be made even if the input level changes due to deterioration until the time of deterioration.

In addition, in order to prevent errors due to charge discharge in capacitor C ₃ , for example, viscosity tube 2 should be
Turn on the switch SW when there is no liquid F in the tank (or, of course, turn on the switch SW only when liquid F is flowing down).
If measurements are carried out, stable measurements can be made with a nearly constant amplification degree.

To further explain based on FIGS. 5 and 6,
First, when there is no liquid F in the viscosity tube 2, gain correction is performed in advance.

At this time, the switch SW shown in FIG. 5 is turned on, and the comparison amplifier _A2 , which is originally a differential amplifier, operates. As a result, the voltage at point b in FIG. 5 becomes equal to the reference voltage Es. This is because the transistor FET of the attenuator AT is controlled by the output of the amplifier _A2 .

In other words, in the case of a new product, the signal waveform at point a in FIG. ₅ is similar to Na in FIG. It will be attenuated to the reference voltage Es, as shown by Nb in Figure 6.

In the case of a product that has been used for a long time, the signal waveform at point a in Figure 5 will be as shown in Figure 6 even if the level L ₂ when there is no liquid F is below the reference voltage level Es for Oa in Figure 6. Like Ob, it will be amplified to the reference voltage Es.

At this time, since the capacitor C ₃ connected in parallel to the amplifier A ₂ in FIG. Even if the switch SW shown in FIG. 5 is turned off, the output of the amplifier _A2 will be held as it was when the gain was corrected earlier.

In addition, the capacitor _C3 connected in series to the gate end of the transistor FET is connected to the liquid F in the viscosity tube 2.
As the light enters and the amount of light increases, the transistor
This is to prevent the FET from responding quickly (that is, the amplification rate of the amplifier _A1 does not change in a short time).

[Effect of idea]

As described above, the present invention is effective even if the light guide group for liquid detection deteriorates due to long-term use, especially at high temperatures, and the difference in characteristics between new and long-term use changes significantly. Since the flow detection can be performed by taking advantage of the fact that the relative characteristic difference between when new and when used for a long time is almost constant, the flow detection is stable and accurate regardless of whether the light guide has deteriorated or not. It has the advantage of not only eliminating the need to change the amplification degree of the amplification device through modification etc. during long-term use, but also preventing sample loss due to malfunction due to the high sensitivity of the amplification device. There are some remarkable practical effects.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the usage state of the embodiment of the present invention, Fig. 2 is a graph diagram explaining the same, Fig. 3 is a block diagram showing the embodiment of the present invention, and Fig. 4 explains the same. FIG. 5 is an electronic circuit diagram showing an embodiment of the present invention, and FIG. 6 is a graph diagram explaining the same. 2...Viscosity tube, 4,5,6,7...Light guide,
12, 13...Phototransistor, FET...
Field effect transistor, AT...attenuator,
Q ₁ ...transistor, A ₂ ...comparison amplifier, Es...
...Reference voltage.

Claims (1)

[Claims for Utility Model Registration] One light guide 4, 6 that emits light into the viscometer 2 of the capillary flow-down type viscometer, and the other light guide 5 that inputs the light that has passed through the viscometer 2. ,7
, a photodetector 12 that detects the light from the other light guides 5 and 7 and outputs a first signal a, and a gain that inputs the first signal a and outputs a second signal b. Input the variable amplifier _A1 , the second signal b, and the reference voltage
and a comparison amplifier _A2 which inputs Es and outputs a signal for gain change to the variable gain amplifier _A1 , and is provided with at least two pairs of comparison amplifiers _A2. A flow detection device for a capillary flow-down type viscometer, comprising a switch SW for controlling input of the reference voltage Es.