JPH06273330A - Turbidimeter - Google Patents

Abstract

PURPOSE:To provide a highly accurate turbidimeter. CONSTITUTION:The turbidimeter for measuring the turbidity of a solution by measuring the intensity of light transmitted through the solution comprises a lens 10 for focusing the light transmitted straightly through the solution and the light scattered by the solution, an optical detector 11 for detecting the intensities of the transmitted light and the scattered light focused by the lens 10, and a shutter 12 for cutting the transmitted light. Turbidity is then determined based on the intensity of scattered light when the transmitted light is cut by means of the shutter 12 and the total intensity of the transmitted and scattered lights when the transmitted light is not cut.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a turbidity measuring device for measuring the turbidity of a solution to be measured. More specifically, the scattered light transmitted through the cell and the intensity of the transmitted light are detected by the same detector, The present invention relates to a turbidity measuring device capable of accurately measuring the turbidity of a solution to be measured without being affected by the temperature characteristics peculiar to a photodiode used in a detector.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram of a conventional turbidity measuring device. In the figure, 1 is a lamp which is a light source, 2 is a collimator lens for collimating the light from the lamp 1, and 3 is a diaphragm,
The parallel light flux emitted from the collimator lens 2 is narrowed down to an appropriate light flux diameter D. Reference numeral 4 denotes a cell having a glass window 4A on the optical path surface. The solution to be measured is supplied from the inlet side and delivered from the outlet side. Reference numeral 5 is a transmitted light detector that measures the intensity I _p of the parallel light flux (transmitted light) that has passed through the cell 4, and 6 is a scattered light detector that measures the intensity I _d of the scattered light that has passed through the cell 4. still,
These detectors are composed of photodiodes or the like.

An amplification circuit 7 amplifies the intensities I _p and I _d of the light input from the transmitted light detector 5 and the scattered light detector 6, and outputs the amplified light intensities to the arithmetic circuit 8. The arithmetic circuit 8 calculates the turbidity T based on the scattered light signal S _d and the transmitted light signal S _p input from the amplifier circuit 7.

[0004]

In such a conventional turbidity measuring device, since the photodiodes used in the detector have their own temperature characteristics, the turbidity can be accurately measured. It was necessary to make the photodiodes of the transmitted light detector and the scattered light detector have the same temperature characteristics. Alternatively, it is necessary to perform a calculation for correcting the difference in temperature characteristics between the photodiodes of the transmitted light detector and the scattered light detector.

The present invention has been made in view of the above point, and is one in which the intensity of scattered light transmitted through a cell and the intensity of the transmitted light are measured by one detector, and the temperature characteristic of the photodiode is measured. It is an object of the present invention to provide a turbidity measuring device capable of accurately measuring the turbidity of a solution to be measured without being affected by.

[0006]

In order to achieve such an object, the present invention provides a turbidity measuring apparatus for measuring the intensity of light transmitted through a solution to be measured and measuring the turbidity of the solution to be measured. A lens that forms an image of the transmitted light that travels straight through the solution to be measured and the scattered light that is scattered by the solution to be measured, and a photodetector that detects the intensity of the transmitted light and the scattered light formed by the lens, A shutter for cutting the transmitted light of the solution to be measured is provided, and based on the sum of the intensity of the scattered light when the transmitted light is cut by the shutter and the intensity of the transmitted light and the scattered light when the transmitted light is not cut. It is characterized by determining the turbidity value.

[0007]

The photodetector obtains the intensity of (scattered light) / (scattered light and transmitted light) from the signal when the shutter is opened and the signal when the shutter is closed. And the photodetector got (scattered light)
The intensity ratio of scattered light and transmitted light is calculated from the intensity of / (scattered light and transmitted light) to obtain turbidity.

[0008]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of the turbidity measuring device of the present invention, and FIG. 2 is a configuration diagram of a main part of the turbidity measuring device of the present invention in a state where a shutter is opened. In the figure, components having the same functions as those in FIG. Reference numeral 10 is a lens having a focal length f provided on the extension of the parallel light flux, and 11
Is a photodetector provided on the optical axis of the lens 10.

The lens 10 forms an image of scattered light emitted from a parallel light flux at a distance a from the lens 10 on a photodetector 11 located at a distance b from the lens 10 and also transmits a parallel light flux (hereinafter, The transmitted light) is once focused on the focal point f, and then focused on the photodetector 11.

Reference numeral 12 denotes a circular shutter provided between the cell 4 and the lens 10, the opening and closing of which is controlled by the motor 13 to control the incident of the transmitted light on the lens 10. 1
3A is a circular position detecting plate, which is attached to the motor shaft 13B and rotates with the rotation of the motor 13. A position detector 14 detects a slit (not shown) provided from the outer periphery of the position detection plate 13A toward the center with a photo sensor (not shown) to recognize the open / closed state of the shutter 12.

The amplifier circuit 7 amplifies the signal S ₁ input from the photodetector 11 and outputs it to the sample hold circuit 15. The sample hold circuit 15 holds the signal S ₃ input from the amplifier circuit 15 based on the latch signal S ₂ output from the position detector 14. In this case, a signal when the shutter 12 is opened (a signal based on the intensities I _d and I _p of the scattered light and the transmitted light) and a signal when the shutter 12 is closed (the intensity of the scattered light only I _d Signal based on the above) is held.

The signal S ₃ held in the sample-hold circuit 15 is output to the arithmetic circuit 8 and the ratio of scattered light to transmitted light is obtained and becomes a turbidity signal T.

Next, the operation of the turbidity measuring device of the present invention will be described. The light emitted from the lamp 1 is collimated by the collimator lens 2 and the diaphragm 3 and emitted to the cell 4. Since the light emitted to the cell 4 is scattered or reflected, the intensity I _t of the total transmitted light that passes through the solution to be measured is I _t = I _d + I _p . Incidentally, I _d is the intensity of scattered light, and I _p is the transmitted light (cell 4
Is the intensity of the parallel light flux that has passed through.

The scattered light at a distance a from the lens 10 is imaged by the lens 10 on the photodetector 11 to have a size of d ₁ . At this time, d ₁ has a relationship of d ₁ = D _X (b / a). On the other hand, the transmitted light forms an image at the focal point f by the lens 10 and is formed on the photodetector 11 in the size of d ₂ . d ₂ is represented by D _X (b−f) / f, and (1 / f) =
From the relationship of (1 / a) + (1 / b), d ₂ = D _X (b /
a) That is, the image is formed on the photodetector 11 in the same size as d ₁ .

When the shutter 12 is turned on (transmitted light is
Only the scattered light is focused on the photodetector 11 by the lens 10 ( when it is shielded) , and is imaged in the size of d ₁ . The intensity I _d of the scattered light detected by the photodetector 11 is amplified by the amplifier circuit 7, and then the sample-hold circuit 15 is operated by the latch signal S obtained by the position detector 14 based on the operation of the shutter 12.
And is output to the arithmetic circuit 8.

When the shutter 12 is turned off (transmitted light is
The scattered light and the transmitted light are converged by the lens 10 on the photodetector 11 ( when not shielded) , and are imaged in the size of d ₁ . Photodetector 11
The scattered light and transmitted light intensities I _d and I _p detected by
After being amplified by the amplifier circuit 7, the position detector 14 is held in the sample hold circuit 15 by the latch signal S ₂ obtained based on the operation of the shutter and is output to the arithmetic circuit 8.

FIG. 3 is a diagram showing a spectrum obtained from the signal of the photodetector. The maximum value A is a signal based on the intensities I _d and I _p of the scattered light and the transmitted light, and the minimum value B is a signal based on the intensity I _d of the scattered light in which the transmitted light is shielded. The arithmetic circuit 8 is obtained by turning on / off the shutter 12 (scattered light) /
The intensity ratio of scattered light and transmitted light is obtained from the intensity of (scattered light and transmitted light) to obtain the turbidity T.

As described above in detail, the turbidity measuring device of the present invention is designed to measure the intensity of transmitted light and scattered light with the same detector, and the influence of the temperature characteristic of the photodiode. The turbidity of the solution to be measured can be accurately measured without receiving the turbidity.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a turbidity measuring device of the present invention.

FIG. 2 is a main part configuration diagram of a turbidity measuring device of the present invention in a state where a shutter is opened.

FIG. 3 is a diagram showing a spectrum obtained from a signal of a photodetector.

FIG. 4 is a configuration diagram of a conventional turbidity measuring device.

[Explanation of symbols]

 10 Lens 11 Photodetector 13 Motor 14 Position Detector 15 Sample Hold Circuit

Claims (1)

[Claims] 1. A turbidity measuring device for measuring the intensity of light transmitted through a solution to be measured to measure the turbidity of the solution to be measured, wherein the transmitted light traveling straight through the solution to be measured and scattered by the solution to be measured. The shutter for cutting the transmitted light of the solution to be measured, a lens for forming an image of the scattered light formed by the lens, a photodetector for detecting the intensity of the transmitted light and the scattered light formed by the lens, and the shutter A turbidity measuring device characterized by obtaining a turbidity value based on the intensity of scattered light when the transmitted light is cut by and the sum of the intensity of the transmitted light and the intensity of the scattered light when the transmitted light is not cut.