JPS5899733A - Turbidimeter - Google Patents

Abstract

PURPOSE:To make it possible to accurately measure the turbidity of a liquid to be measured having a low turbidity without requiring increasing the measuring apparatus in size, by repeatedly passing light through the liquid and then, detecting the light quantity ratio between the transmitted light and the light-source light. CONSTITUTION:The beam of light emitted from a light-source lamp 13 is formed into a parallel beam by a convex lens 14 and is projected onto a cell 12. Then, the light beam is passed through a liquid 11 to be measured, where the beam is reduced in luminous intensity, and enters a rectangular prism 17. The light beam is 90 deg. reflected by the upper oblique side 21 of the rectangular prism 17 to travel downward and is 90 deg. reflected by the lower oblique side 28 so as to be projected onto the cell 12 again and is then passed through the liquid 11 to enter a rectangular prism 18. Further, the light beam is passed through the liquid 11, the rectangular prism 17, the liquid 11 and the rectangular prism 18 and is projected onto the cell 12, and after repeatedly passing through the liquid 11 five times, the light beam enters a photocell 15 for transmitted light. The turbidity of the liquid 11 is calculated by an arithmetic device 25 from the luminous intensity of the transmitted light and that of the light-source light detected by a photocell 16 for light-source light.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical turbidity meter that can measure the turbidity of water, etc. with high accuracy.

Conventionally, as this type of apparatus, one having a structure as shown in FIG. 1 has been used. In this figure, (1) is the liquid to be measured whose turbidity is to be measured, and (2) is - the liquid to be measured (5).
(1) is a transparent cell for passing through and exposing the liquid to be measured (1), (3) is a light source lamp, (4) is a convex lens to make the light beam of the light source lamp (3) parallel, and (5) is a transparent cell for passing through the liquid to be measured (1). ) is a photocell for transmitted light that receives the measurement light transmitted through the light source rung and converts it into an electrical signal, and (6) is a light source monitor photocell that directly receives the light beam from the light source rung (3) and converts it into an electrical signal. Cell, (7) is the above two photocells (5)? (6)
An arithmetic unit (8) is an output terminal of the arithmetic unit (7) which calculates the turbidity χ by calculating the logarithm of the ratio of the signals obtained.

The light source lamp (3) is provided at the focal point of the convex lens (ri), and the light rays emitted from the light source lamp (3) pass through the convex lens (ri).
4), the light is converted into parallel light, passes through the liquid to be measured (1), is attenuated according to the turbidity of the liquid to be measured (1), and its luminous intensity is detected by the transmitted light photocell (5). Ru. Luminous intensity I of transmitted light detected by the transmitted light photocell (5)
and the light detected by the light source photocell (6), the photometric process for attenuation. There is a relationship between Equation (1) (Lamber
t -Beer's law)- holds true.

I = IoeXP (-etz)'
---(1) Here, Io: luminous intensity of the light source, I: luminous intensity of transmitted light.

χ: Turbidity 9. ξ: Attenuation coefficient, t: Cell length According to this law, when the turbidity χ is low, the amount of light attenuated by absorption or scattering is small.
) is the light intensity of the transmitted light detected by the light source lamp (3
) is almost the same as the luminosity IO. Therefore, when measuring turbidity χ with a conventional turbidity meter, the S/N ratio in the low concentration region is poor and the measurement error becomes large. For this reason, when measuring a liquid to be measured with low turbidity with a conventional turbidity meter, the length t of the cell (2) must be increased (by increasing the amount of light attenuation of the transmitted light) in order to increase the S/N ratio. It was necessary to make the device thicker, and as a result, the entire device became thicker.

The present invention solves the above-mentioned drawbacks of the conventional methods, and allows the turbidity of low-turbidity test liquids to be accurately measured without making the device thicker by repeatedly transmitting transmitted light through the test liquid. The purpose is to provide a turbidity meter that can measure turbidity.

The gist of the present invention is a turbidity meter that detects the amount of light transmitted through a liquid to be measured and light source light, which has an optical system that repeatedly transmits the transmitted light to the liquid to be measured.
For example, two right-angled prisms are used as the light system that repeatedly transmits the transmitted light through the liquid to be measured.

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Fig. 2, (6) is a transparent cell through which the liquid to be measured (1 m) can be passed continuously.The cell (2)
A light source lamp (2) is provided on one side of the light source lamp (2).
6) and the cell (6) is provided with a convex lens α◆2,
The convex lens Q4 is arranged at 5 so that its focal point overlaps with the light source lamp (2) in order to convert the light rays emitted from the light source lamp (to) into parallel rays. A light source light monitoring photocell cLQ for monitoring the luminous intensity of the light source lamp (6) is provided near the light source lamp (6).

Next, two right angle prisms (b) and (to) are provided at substantially extended positions of the light source lamp (to) and the convex lens α so as to sandwich the cell (6). The right angle prism (B) on the opposite side of the light source lamp (6) through the 7° lens (B) has its long side (G)
along the right side of the cell (B) IC, and align the upper hypotenuse (2I
) is arranged so that it intersects with the extension line of the light source lamp (to) and the convex lens a◆.

Similarly to the right-angle prism (b) on the opposite side, the right-angle prism (on the side of the light source lamp) has its long side ■ along the left side (c) of the cell (2), and its upper hypotenuse (good) is a convex lens α◆ Measurements from .

Shift it below the right angle prism (b) on the opposite side so as not to block the light.

Furthermore, a transmitted light photocell (g) is provided on the opposite side of the light source lamp (to) via the cell (6), and its output end is connected to both photocells (g) together with the light source monitor photocell (g).
g), is connected to an arithmetic unit (25) that calculates the logarithm of the output ratio of αQ. Transmitted light photocell (g) is used as a light source lamp)
-(5) is the output end of the arithmetic unit (c), which is placed at a position corresponding to the lower hypotenuse (a) of the right-angle prism on the side.

Next, the present invention will be explained in detail. 1. The light rays emitted from the light source lamp (6) are formed into parallel light rays by the convex lens, and
), passes through the liquid to be measured (b), reduces the luminous intensity, and enters a right-angled prism (b). The light beam is reflected by 90 degrees from the upper hypotenuse (21) of the right angle prism and goes downward, and is reflected by 90 degrees from the lower hypotenuse (to) and is projected onto the cell (2). Its luminous intensity is reduced and it enters a right-angled prism (c). The ray of light is reflected by 90 degrees at the lower hypotenuse (c) of the right-angled prism () and goes upwards, and by 90 degrees at the upper hypotenuse (good).
The light beam is reflected at 7-(6) and is transmitted through the liquid to be measured (l) to reduce its luminous intensity and enters the right-angle prism (b).The light beam is reflected at 90 degrees at the lower hypotenuse (c) of the right-angle prism. The light beam travels upward, is reflected by 90 degrees at the upper hypotenuse (21), is projected onto the cell (b), and is transmitted through the sample liquid α, where its luminous intensity is reduced and enters the right angle prism α peak. (
It is reflected by 90 degrees from the upper hypotenuse (2) of 118 and goes downward, reflected by 90 degrees from the lower hypotenuse (A) and projected onto the cell (6), and transmitted through the liquid to be measured (B) to reduce its luminous intensity. and enters the transmitted light photocell (g).

Therefore, the luminous intensity of the transmitted light is reduced in the same way as when the cell length t is increased by five times by repeatedly passing through the liquid to be measured (b) five times.

The turbidity χ is calculated according to the following equation (B), which is a modification of the above equation (A),
Calculate with arithmetic unit (e).

The calculated turbidity 2 is displayed on a display (not shown) connected to the output end of the computing unit (c).

In the above embodiment, the case where two prisms are used has been described, but the number of prisms used may be six or more, or may be one. When two or more are used, the sensitivity can be increased, so it is suitable for low turbidity, and when one is used, it is suitable for relatively high turbidity.

Since the present invention has the configuration as described above, it has the effect of increasing the accuracy of measured values (turbidity) without increasing the size of the device.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional turbidity meter, and FIG. 2 is an explanatory diagram of a turbidity meter that is an embodiment of the present invention. 11-Measurement liquid, 12-cell, 13-light source lamp, 14
- Convex lens, 15 - Photocell for transmitted light, 16 - Photocell for monitoring light source light, 17.18 - Right angle prism agent Patent attorney Shin Kuzuno -

Claims (1)

[Claims] A turbidity meter that detects the light intensity ratio between transmitted light transmitted through a liquid to be measured and light from a light source, the turbidity meter comprising an optical system that repeatedly transmits the transmitted light through the liquid to be measured.