JPH11142333A - Light responsive particle densitometer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the obtaining of concentration in a simple method, by outputting a light reception signal as a binary rectangular wave corresponding to time when an optical axis is blocked by suspended particles and time when the optical axis is not blocked according to changes in the reception of light from a light emitting part, and integrating outputted light reception signals. SOLUTION: Light is emitted by a light emitting part 1 connected to a d.c. power source 6 and is received by a light receiving part 2. Obtained light reception signals are integrated by an integrating circuit B. A voltage lower than a voltage corresponding to output at the time of the total blocking of light is outputted by the integrating circuit B according to a period of time during which light from the light emitting part 1 is blocked, and the ratio of the outputted voltage to a reference voltage indicates the ratio of blocking time in a predetermined time. When suspended particles in a fluid pass the optical axis between the light emitting part 1 and the light receiving part 2 in this way, an output voltage Vout becomes a low voltage. In the case of the absence of suspended particles, the output voltage Vout is at a high electric potential. Therefore, the voltage Vout is expressed as a binary rectangular wave due to the presence or absence of suspended particles in the optical axis. Expressing the output voltage Vout in a rectangular wave eliminates errors even at the time when the light emitting part 1 and the light receiving part 2 are stained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid particle concentration meter for measuring the amount of suspended solid particles in a fluid, and more particularly to a suspension suitable for measuring suspended particles having a particle size of 0.1 mm or more. It relates to a particle concentration meter.

[0002]

2. Description of the Related Art In measuring the concentration of particles contained in a fluid to be measured, light or ultrasonic waves are continuously transmitted through the fluid, and when the light or ultrasonic waves pass through the fluid, the light or ultrasonic waves are transmitted. Because it is attenuated by particles contained in the fluid,
There is a turbidity meter for determining the concentration of suspended particles using this attenuation rate, and is mainly used for measuring the concentration of suspended particles of 10 μm or less.

[0003]

In the above-mentioned conventional apparatus, when the size of the suspended particles is about 10 μm or less in the turbidimeter, the attenuation of light or ultrasonic waves and the concentration of the suspended particles are reduced. Although a satisfactory correlation is obtained between the particles, the diameter of the suspended particles has a size of 0.1 mm or more, despite the increasing need for measuring the concentration of relatively large suspended particles in recent years. , The above-mentioned correlation starts to break down. Further, in the case of suspended particles having a size of 0.5 mm or more, the reliability of the obtained suspended particle concentration is greatly reduced in the measurement by the above method. Was.

Further, in the above-mentioned conventional method, the concentration is calculated from the attenuation rate based on the amount of transmitted light or the volume of ultrasonic waves in a fluid containing no suspended particles. If the surface of the light-emitting unit and light-receiving unit becomes contaminated during the concentration measurement process, the attenuation rate calculated from the amount of light received by the light-receiving unit does not indicate the attenuation due to transmission through the fluid. Since the rate is deviated, there is a problem that complicated processing is required such that the surfaces of the light emitting unit and the light receiving unit need to be always kept clean.

The present invention has been made in view of such circumstances, and is intended for use in the case of relatively large suspended particles having a diameter of 0.1 mm or more, and even when the size of the suspended particles is not constant. In order to obtain a suspended particle concentration meter that can accurately measure the concentration of suspended particles and that does not affect the measurement performance even if the detection unit becomes dirty, it responds to changes in light reception from the light emitting unit Then, when the suspended particles interrupt the light path and when the light path is not interrupted, the received light signal is output as a binary rectangular wave corresponding to each, and by integrating the signals, the interruption probability obtained from the time ratio at the interruption is output. Found that the concentration was accurately proportional to the concentration of the suspended particles to be treated, so that the light using a smoothing circuit that could determine the concentration by a simple method without using an expensive computer or a high-precision clock was used. Responsive particle densitometer The purpose is to provide.

[0006]

According to the first aspect of the present invention,
A light-emitting unit, a light-receiving surface facing the light-emitting surface at a position facing the light-emitting surface of the light-emitting unit, receiving light emitted from the light-emitting unit, converting the light into an electric signal, and outputting the electric signal And an integrator for integrating the electric signal output from the light receiving unit. According to a second aspect of the present invention, in the photoresponsive particle concentration meter according to the first aspect, the integrator comprises a smoothing circuit. According to a third aspect of the present invention, in the photoresponsive particle densitometer according to the first aspect, an interval between the light emitting unit and the light receiving unit is 3 to 20 mm, and an optical path between the light emitting unit and the light receiving unit is set. The diameter is not more than 20 times the diameter of the particle to be measured.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a photoresponsive particle concentration meter according to an embodiment of the present invention will be described with reference to the drawings. FIG.
FIG. 3 is an outline view of a system using the photoresponsive particle densitometer according to the embodiment. In this drawing, reference numeral 1 denotes a light emitting unit, which may be a light emitting element itself of an LED (light emitting diode) or an end of an optical fiber that guides light from the light emitting element. Reference numeral 2 denotes a light receiving unit, which may be a light receiving element itself such as a phototransistor or an end of an optical fiber for guiding light from the light emitting element to the light receiving element. The light receiving unit 2 is supplied with a DC low voltage Vc, and the light emitting unit 1 and the light receiving unit 2 constitute a detecting unit A. Reference numeral 3 denotes a fluid containing suspended particles to be measured, which is placed inside the container 5. Reference numeral 4 denotes a stirrer, which stirs the fluid 3 in the container 5 to make the density of the suspended particles uniform and increase the accuracy of the measurement.

Reference numeral 6 denotes a DC power supply for supplying a constant voltage to the light emitting unit 1. Reference numeral B denotes an integration circuit, which includes a capacitor 7, a fixed resistor 8a, and a variable resistor 8b.
An output from the light receiving section 2 is connected to a variable contact section of the variable resistor 8b. The end of the variable resistor 8b is connected to one end of the fixed resistor 8a and is output to the outside as an output Vout, which is the output of the present photoresponsive particle densitometer. The other end of the fixed resistor 8a is grounded. A capacitor 7 is connected between the output Vout and the ground potential in parallel with the fixed resistor 8a.
Is connected. The amplitude value of the output Vout is adjusted by adjusting the position of the contact point of the variable resistor 8b.

Next, the operation of this embodiment will be described. First, the DC power supply 6 is connected, light is emitted from the light emitting unit into the fluid, and the light is received in the light receiving unit 2 using, for example, a photoelectric switch circuit or the like. The signal from the light receiving unit thus obtained is integrated using an integrating circuit B such as an RC smoothing circuit. The integration circuit outputs a voltage lower than a voltage (reference voltage) corresponding to the output when the light from the light emitting unit 1 is cut off, and the ratio of this voltage to the reference voltage within a predetermined time. Shows the ratio of the cut-off time in. That is, the output value indicates the ratio of the passage time of the suspended solid particles, which corresponds to the total volume of particles in the unit volume of the suspension, even if the size of the particles is not uniform.

Thus, when the suspended particles in the fluid pass on the optical axis of the light-emitting portion to the light-receiving portion, the light on the optical axis is thereby blocked, and the output voltage Vout becomes low. When no suspended particles are present on the optical axis, the output voltage is at a high potential. Therefore, when the output voltage Vout is graphically displayed, a rectangular wave having a binary value depending on the presence or absence of the suspended particles on the optical axis. It is expressed as

The output of the light receiving section 2 receiving the light emitted from the light emitting section 1 is processed by a photoelectric switch (not shown), so that the output voltage varies with time, and the suspended particles interrupt the optical path. 2 for when and when not
It becomes an intermittent DC pulse voltage (rectangular wave) consisting of a value.
This is one in which the period changes randomly, an example of which is shown in FIG. Here, the horizontal axis represents time, the vertical axis represents voltage, and when the voltage is {0} (low potential), suspended particles interrupt the optical path between the light emitting unit and the light receiving unit. Is {1} (high potential), it means that there are no suspended particles in the optical path.

By using a rectangular wave of two values in this way, the problem of using an analog attenuation factor is eliminated, and even when the light emitting portion and the light receiving portion are contaminated as described above, the problem is caused. The error is almost eliminated.

FIG. 3 shows the relationship between the concentration of immobilized cells and the output voltage from the integrating circuit in an organic compound reactor using immobilized cells as suspended particles having an average diameter of 0.5 mm. Here, the horizontal axis represents the immobilized bacterial cell concentration (%), and the vertical axis represents the detection output integrated value (V). As is clear from FIG. 3, the concentration is accurately proportional to the concentration of the suspension. FIG. 3 shows an excellent correlation when the concentration of the immobilized cells is in the range of 4 to 8%. However, when the sensitivity is lowered, the correlation at a lower concentration is increased. A correlation in the range can be obtained.

In the above description, the distance between the light emitting section 1 and the light receiving section 2 is preferably 2 to 20 mm, and more preferably 5 to 10 mm. The diameter of the optical path of the light that exits from the light emitting unit 1 and reaches the light receiving unit is 2 times the diameter of the suspended particles to be measured.
It is preferably 0 times or less.

As described above, the processing according to the embodiment of the present invention and the irregular wave output from the light receiving unit according to the interruption of the light by the suspended particles in the fluid to be measured by the rectangular wave obtained by the light receiving unit. Is compared with a method of calculating the integrated value and calculating the concentration of suspended particles from the signal by inputting the signal to a computer. It is excellent in portability, and has an advantage that, even when performing measurements outdoors, there is no need to secure a power source or to use a protection device from the external environment because an integrating circuit using a passive element including a resistor and a capacitor is used.

Further, compared with the case where the light receiving signal from the light receiving section is processed by using a normal pulse converter, the pulse width generated in the object such as the object to be measured is not constant.
According to the present invention, a more accurate measurement can be performed than by a pulse converter.

[0017]

As described above, according to the photoresponsive particle concentration meter according to the present invention, the concentration of suspended particles having a diameter of 0.1 mm or more can be measured with high accuracy. It does not cause measurement errors due to contamination of the light-receiving unit or the like, and eliminates the need to provide an external device such as a computer for each individual concentration measuring tank to be measured, and thus can measure the concentration of suspended solid particles inexpensively and easily. be able to. Furthermore, since the computer is not occupied, the entire measurement device is excellent in portability.In addition, since an integrating circuit using passive elements consisting of a resistor and a capacitor is used, even when performing measurement outdoors, it is necessary to secure a power supply and to protect the external environment. It has the advantage that no protective device is required.

[Brief description of the drawings]

FIG. 1 is a block diagram of a photoresponsive particle densitometer according to an embodiment of the present invention.

FIG. 2 is a square wave output signal measured by a photoresponsive particle densitometer according to an embodiment of the present invention.

FIG. 3 is a graph showing the relationship between the concentration of suspended particles and the output voltage using a photoresponsive particle densitometer according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Light-emitting part 2 ... Light-receiving part 3 ... Fluid 4 ... Stirrer 5 ... Container 6 ... DC power supply 7 ... Condenser 8a, 8b ... Resistance A ... Detection part B ... Integration circuit

Claims (3)

[Claims] A light-emitting unit, a light-receiving surface facing the light-emitting surface at a position facing the light-emitting surface of the light-emitting unit, receiving light emitted from the light-emitting unit, converting the light into an electric signal, A photoresponsive particle densitometer comprising: a light receiving unit that outputs the signal; and an integrator that integrates an electric signal output by the light receiving unit. 2. The photoresponsive particle concentration meter according to claim 1, wherein said integrator comprises a smoothing circuit. 3. The distance between the light emitting section and the light receiving section is 3 to 3.
2. The photoresponsive particle densitometer according to claim 1, wherein the diameter is 20 mm, and the diameter of an optical path between the light emitting unit and the light receiving unit is 20 times or less the diameter of a particle to be measured.