JPS6057236A - Method for measuring reflection density in biochemical analysis - Google Patents

Abstract

PURPOSE:To decrease measuring errors and to provide higher accuracy, reliability and reproducibility by irradiating a ray to the measuring surface of a measuring element and performing multi-point sampling at the same point. CONSTITUTION:A ray 2 is irradiated to a measuring element 6 and light 2a reflected from the measuring surface is transmitted via a photodetector 10 to a photodetecting element 20 and a part of the ray 2 is transmitted as reference light to a photodetector 21. The respective output signals from the detectors 20 and 21 are respectively subjected to high-voltage conversion 30, 31 and are inputted to a compensating circuit 40 by which the signals are logarithmically converted. The output from the circuit 40 and the output from a circuit 51 for generating a reference voltage are changed over by a switch 50 and are inputted to an A/D converter 60. The converted output is fed to an arithmetic circuit 70 and the correct conversion value for the output from the circuit 40 is calculated. Sampling at the same point of the element 6 is performed many times while a shutter vane 8 is open and the average value thereof is determined. The measuring error by the noise of the element 6 is thus removed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a method for analyzing the components of a liquid sample by irradiating a measuring element with a photometric beam and measuring the reflection density of the reflected light. This invention relates to a method for measuring reflection density in chemical analysis.

[Conventional technology]

Generally for liquid samples such as blood and serum.

In many cases, it is necessary to know whether or not a particular component is contained in the liquid sample, or the amount of that component.

For this purpose, chemical analysis using reaction reagents is performed.

There are two methods for chemical analysis of liquid samples: the dry method and the wet method. Of these, the dry method uses a liquid sample measurement element consisting of a thin plate impregnated with a specific reagent sandwiched between mounts. A liquid sample to be analyzed is supplied dropwise to the element, placed in a thermostatic chamber for reaction, and the liquid sample and reagent are allowed to react, and the progress or results of the reaction are monitored.

For example, this method is a method of measuring and detecting a change in color density due to a reaction using an optical density meter or other means, and is very convenient in that a liquid sample can actually be treated as a solid.

However, when a large number of samples are individually dropped onto the measuring element,
It is difficult and troublesome to measure color density changes due to reactions using an optical density meter, so recently a disk in which a plurality of measuring elements are fixed at equidistant positions on the same circle is used.

The disk is installed so that it can be rotated at a constant angle, and the measuring surface of the measuring element is sequentially irradiated with a measuring beam of a desired wavelength.
A biochemical analyzer has been developed that measures reflected concentration by converting reflected light from the measurement surface of the measurement element into an electrical signal.

In the past, reflection density was measured by one sampling, which made it impossible to remove unstable elements in the optical and electrical systems, resulting in large errors in measured values, low measurement accuracy, and poor reliability and reproducibility. It was bad.

[Purpose and structure of the invention]

In view of the above points, the present invention performs multi-point sampling at the same point when irradiating a photometric light beam onto the measurement surface of a measurement element and measuring its reflection density.

By taking the average value, unstable elements in the optical and electrical systems, such as sensor noise, can be effectively removed and measurement errors can be significantly reduced. The purpose of this invention is to provide a method for measuring reflection density in chemical analysis.

[Embodiments] Next, the present invention will be described based on embodiments shown in the accompanying drawings.

FIG. 1 shows an example of the configuration of a system that implements the measurement method according to the present invention.

In the figure, 1 is a light source that emits a photometric light beam 2. On the optical path of the photometric light beam 2, there is a condenser lens 3 for condensing the photometric light beam 2. Cylindrical slit 4 for making the irradiation diameter of the photometric light beam 2 constant. Mirrors 5 for changing the optical path of the photometric beam 2 are installed, and on the optical path of the photometric beam 2 changed by the mirror 5, there is a measuring element 6 that has reacted with a sample such as blood.
is located.

Furthermore, between the condenser lens 3 and the cylindrical slit 4, 45
A transparent glass 7 tilted at an angle of 70° and shutter blades 8 are installed. The transparent glass 7 is used to branch a part of the photometric light beam 2 as reference light in order to understand the fluctuation in the light intensity of the photometric light beam 2, and the shutter blade 8 is used to open and close the photometric light beam 2 irradiating the measurement element 6. It is rotationally driven by a rotary solenoid 9 so that it can move forward and backward on the optical path.

A plurality of light receivers 10- for receiving the reflected light 2a generated by the irradiation are arranged around the irradiation point of the measurement element 6, and the light receivers 10--1-- receive the received light in a first direction. An optical fiber 11- for transmission to the light receiving element 20 is connected. Similarly, a light receiver 12 is disposed on the optical path of a part of the reference light 2b branched by the transparent glass 7, and the light receiver 12 has an optical fiber that transmits the received reference light to the second light receiving element 21. 13 are connected. Note that the reflected light 2a may be directly received by a light receiving element, and the optical fibers 11 and 13 may be omitted.

The first light-receiving element 20 and the second light-receiving element 21 convert the element reflected light 2a and the reference light 2b into electric signals (current values) of a magnitude corresponding to each light amount, and are converted by a photoelectric element such as a photodiode. It is configured.

30, a current-voltage converter that converts the first electrical signal generated by the first light receiving element 20 into a voltage value V mea;

31 is a current-voltage converter that converts the second electric signal generated by the second light receiving element 21 into a voltage value V ref.

40 is a voltage V m corresponding to the amount of light reflected from the measuring element 2a.
ea and the voltage V r corresponding to the light intensity of the reference light 2b
By differentially amplifying ef.

This is a compensation circuit that compensates for variations in the light amount of the measuring element reflected light 2a based on variations in the light source of the photometric light beam 2. The compensation circuit 40 consists of a logarithmic converter, and the input voltages Vmea, Vref and the output voltage VX are expressed as Vx = K]og (Vref /Vm
ea) It is expressed by a relational expression where K is a constant number.

50 is a switching circuit, and 60 is an A/D converter.

The switching circuit 50 is connected to the input terminal 5 of the A/D converter 60.
0a, the output terminal 50b of the compensation circuit 40, the terminal 50c of the reference voltage generation circuit 51 set to a constant reference voltage VH, and the terminal 50d set to a reference voltage VL smaller than the reference voltage Vl+, in sequence. It is possible to switch. This switching circuit 50z is composed of analog switches, and each terminal is switched by a selection signal generator 5.
This is done by a signal from 2.

The A/D converter 60 adjusts the output Vx of the compensation circuit 40 and the reference voltage Vl according to the switching of the switching circuit 50.
It inputs and samples l and VL, and outputs a digital conversion value corresponding to each value. This sampling is performed by a pulse signal sent from the sampling pulse generator 61, and a plurality of samplings can be commanded by -times of irradiation.

70 is a reference voltage value Vl (, VL and the output Vx of the compensation circuit 40 are inputted to the A/D converter 60 and each conversion output value is obtained, so that the output of the compensation circuit 40 becomes a correct digital conversion value. This is an arithmetic circuit that performs calculations.The arithmetic circuit 70
is for correcting errors in the A/D converter 60. Immediately, the input voltage to the A/D converter 60 is VA,
Letting the output voltage after digital conversion be VD, the following relational expression holds true: VD = a VA + b - - - - - - (2). Here, a and b are coefficients that change due to changes over time and the like.

Therefore, the input voltage of the A/D converter 60 is Vx.

Output value VD after digital conversion when Vll and VL
x, VDL, VDL is VDx = a Vx + b ---1---■V1 sho = a Vll + b ----------■■mouth L
a Vl, + b -----■. The solid line in FIG. 2 shows this state. If you delete coefficients a and b from the above formulas ■, ■, and ■ and find the formula related to ■, it is the reference voltage value, and VDII, VDL, and VDx are the output values after digital conversion, so in formula 0, does not include error factors due to changes over time, etc.

By substituting each value into the above equation 0 and calculating, the correct digital conversion value of Vx can be found. Said calculation time 1i! &70 executes the calculation of the above equation 0, and the broken line in FIG. 2 shows the result of this calculation.

The digital conversion value is obtained many times while the shutter blade 8 is open, and the arithmetic circuit 70 displays the average value as a measured value. This causes noise (
The measurement accuracy is improved by removing irregularities in the measured values due to the effects of thermal noise, Johnson noise, etc.

The reflection density measurement method in biochemical analysis according to the present invention will be explained with reference to the above system configuration.

First, the light source 1 is turned on while the optical path of the photometric light beam 2 is blocked by the shutter blade 8.

Next, the rotary solenoid 9 is driven by the signal when the measuring element 6 is placed at the irradiation position, and the shutter blade 8
is removed from the optical path, and the measuring element 6 is irradiated with the photometric light beam 2. The reflected light 2a from this measuring element 6 is transmitted to a light receiver 10-
The received light is transmitted to the first light receiving element 20 via the optical fiber 11-. On the other hand, a part of the photometric light beam 2 is branched as a reference light by the transparent glass 7 and transmitted from the light receiver 12 to the second light receiving element 21 via the optical fiber 13.

The first light receiving element 20 outputs a first electrical signal corresponding to the amount of reflected light 2a, and the second light receiving element 21 outputs a first electric signal corresponding to the amount of reflected light 2a.
A second electrical signal corresponding to b is output. The first and second electrical signals are converted into voltages Vmea and Vref, respectively, by current-voltage converters 30.31.

The voltage-converted signals Vmea and Vref are input to a compensation circuit 40 consisting of a logarithmic converter and are logarithmically converted, and as a result, the compensation circuit 40 calculates Vx = K log (Vref / Vmea).
produces an output Vx.

As is clear from this equation, even if the photometric light beam 2 irradiating the measuring element 6 changes, the reference light obtained by branching a part of the photometric light beam 2 also changes at the same rate, so Vref /
This is canceled out by Vmea, and the output Vx changes only due to differences in reflection density due to differences in liquid samples, and errors due to variations in the amount of irradiated light can be eliminated.

Therefore, the output Vx from the compensation circuit 40 and the voltages VH and VL from the reference voltage generation circuit 51 are transferred to the switching circuit 5.
A/D converter 6 selectively according to the switching of the switch 0
0, the A/D converter 60 converts it into digital,
The converted value is transmitted to the arithmetic circuit 70. The converted value of this A/D converter 60 contains an error due to the A/D converter itself.

The conversion value Vx obtained in this manner does not include errors due to fluctuations in the light intensity of the photometric light beam or errors caused by the A/D converter 60, and is a function that changes depending on the component reacting with the reagent of the measuring element 6.

Then, with the shank vane 8 open, sampling is performed at the same point on the measuring element 6 many times, and the average value is calculated to eliminate measurement errors due to noise in the light receiving element.

In the above embodiment, the arithmetic circuit 70.degree. selection signal generation circuit 52. The operations of the sampling pulse generator 61 and the like can also be performed by a microcomputer.

〔Effect of the invention〕

As described above, this invention is characterized by performing multi-point sampling at the same point and taking the average value when measuring the reflected density by irradiating the measurement surface of the measurement element with a photometric light beam. Measured values are not affected by sensor noise, etc.

Therefore, highly accurate measurement values with significantly reduced measurement errors for the entire system can be obtained, ensuring reliability.

This has the excellent effect of significantly improving reproducibility.

[Brief explanation of drawings]

The figures show an embodiment of the present invention, FIG. 1 is a block diagram showing the configuration of the system, and FIG. 2 is a graph showing values after digital conversion and values after correction. 1 - Light source 2 - Luminous flux 3 - Condensing lens 4 - Cylindrical slit 5 - Reflection mirror 6 - Measuring element 7 - Transparent glass 8 - Shutter blade 9 - Rotary solenoid 10.12 - Light receiver 11. 13・−・−
Optical fiber 20.21-light receiving element 30.31-・-
Current-to-voltage converter 40 - Compensation circuit 50 - Switching circuit 60 - A/D converter 70 - Arithmetic circuit Patent applicant Konishiroku Photo Industry Co., Ltd.

Claims (1)

[Claims] When irradiating the measurement surface of the measurement element with a photometric light beam and measuring its reflection density, multi-point sampling is performed at the same point.
A method for measuring reflection concentration in biochemical analysis, characterized by taking the average value.