The present invention relates to automatic analyzers that examine substances in biological samples such as blood and urine and particularly to an automatic analyzer having a scattered-light measuring device.
An example of an automatic analyzer used for clinical purposes is a biochemical analyzer that examines a particular substance in a biological sample (e.g., blood and urine) by using a reagent that exhibits color changes when reacting with that substance. Such an analyzer is designed to radiate light onto a sample-reagent mix and measure the intensity of transmissive light passing through the sample-reagent mix on a wavelength-by-wavelength basis, thereby measuring color changes quantitatively.
Other than such analyzers that examine transmissive light, there are also medical analyzers that measure the size or amount of particles in a sample using scattered light. Such analyzers detect, for example, solid substances floating in urine or perform an immunoassay by examining agglutination reactions of latex particles. Such analyzing methods are disclosed in Patent Documents 1 and 2 shown below, for example.
Patent Document 1: JP-2010-32505-A
Patent Document 2: JP-2007-309765-A
To measure scattered light, a photodetector is disposed at an angle with respect to the axis of light radiated from a light source. However, when the light scattered from a sample-reagent mix in a reaction vessel is measured, the intensity of the scattered light varies if it passes through the surface of the sample-reagent mix or through a corner of the reaction vessel. To ensure consistent measurements, it is therefore desired to measure only the scattered light passing through the same plane of the reaction vessel. However, the installation position of the photodetector within an automatic analyzer is limited because reaction vessels used are small and also because the analyzer often includes a thermostat tank for maintaining the temperatures of the reaction vessels at a constant value.
An object of the invention is to provide an automatic analyzer having a scattered-light detecting optical system that allows relatively free design of reaction vessels in terms of their sizes and shapes.
To achieve the above object, the invention provides an automatic analyzer configured as follows.
The automatic analyzer includes: a reaction vessel in which a sample is caused to react with a reagent; a reaction disk on which to place reaction vessels in the form of a circle; a reaction disk rotating mechanism for rotating the reaction disk; a light source for radiating light to be measured onto one of the reaction vessels; and a photodetector for detecting transmissive light radiated from the light source and passing through a sample-reagent mix in the one of the reaction vessels. The automatic analyzer further includes an optical system for causing the light source to radiate light onto one of the reaction vessels at an angle with respect to a plane of the one of the reaction vessels.
The above description may also be represented as follows.
The automatic analyzer includes: a reaction vessel in which a sample is caused to react with a reagent; a reaction disk on which to place reaction vessels in the form of a circle; a reaction disk rotating mechanism for rotating the reaction disk; a light source for radiating light to be measured onto one of the reaction vessels; and a photodetector for detecting transmissive light radiated from the light source and passing through a sample-reagent mix in the one of the reaction vessels. The reaction vessels are cuboid-shaped or cylinder-shaped, and the automatic analyzer further includes an optical system for causing the light source to radiate light onto one of the reaction vessels at an angle with respect to a plane of the one of the reaction vessels.
In a conventional optical system for scattered light detection, a light source is often disposed on an axis that passes through the center of a reaction vessel and is parallel to a longitude line of a reaction disk, so that measurement of transmissive light can also be performed. In other words, when the reaction vessel is cuboid-shaped, the common practice is to cause the light source to radiate light onto the reaction vessel at 90 degrees with respect to a surface of the reaction vessel. A transmissive-light detector is also disposed on the same axis. Under this method, the angle of scattered light relative to the optical axis of the light source cannot be increased too much. This is because, when the angle of scattered light is increased excessively relative to a horizontal plane, the scattered light may collide with the boundary between the reaction vessel and the surface of a sample-reagent mix within the vessel or with a bottom corner of the vessel. In contrast, the present invention is characterized in that the optical axis of the radiated light is disposed at a particular angle so that the angle of scattered light relative to a horizontal or vertical plane can be made larger.
In accordance with the invention, it is possible to provide an automatic analyzer having a scattered-light detecting optical system that allows relatively free design of reaction vessels in terms of their sizes and shapes.
Embodiments of the present invention will now be described with reference to
When the angle θ0 is assumed to be the optimal angle for scattered light detection, the light source angle θ1 and the detection angle θ2 are determined such that θ1+θ2=θ0. Because the height of the surface of the sample-reagent mix is smallest when the optical axis θ1 of the radiated light is equal to the angle θ2 set for the scattered-light detector (when θ1=θ2), the angle θ2 set for the scattered-light detector is equal to θ0/2.
Assume, for example, that θ0=45°, the reaction vessel is square in cross section, and the width 14 of the reaction vessel 3 is 5 mm. Further assume that the optical axis 8a of the radiated light and the scattered-light detecting axes 8b and 7b cross at a point 15 and that the distance 14 inside the reaction vessel (the width of the reaction vessel) is 2.5 mm. In that case, the liquid surface height can be in the range of 1 mm (2.5 mm×tan 22.5°) to 2.5 mm (2.5 mm×tan 45°).
Because a cross section of the reaction vessel is 25 mm2 (5 mm×5 mm), the amount of the sample-reagent mix can be reduced to the range of 25 μl to 62.5 μl. Accordingly, the running cost of reagents can be reduced approximately by half.
A reaction vessel rinse mechanism 18 cleans reaction vessels by discharging and suctioning water or a detergent into and from the reaction vessels 3. A sample dispenser 19 suctions a sample from one of sample vessels 21 placed on a sample vessel setting table 20, transfers the sample to a sample dispensing position 22 of a reaction disk, and discharges the sample into one of the reaction vessels 3. After the sample discharge, the sample dispenser 19 is cleaned by a sample dispenser rinse mechanism 23. A reagent dispenser 24 suctions a reagent from one of reagent vessels 26 placed on a reagent vessel setting table 25, transfers the reagent to a reagent dispensing position 27 of the reaction disk, and discharges the reagent into the sample-containing reaction vessel 3. After the reagent discharge, the reagent dispenser 24 is cleaned by a reagent dispenser rinse mechanism 28. The sample to be examined and the reagent are mixed by a stirring mechanism 29, which is cleaned by a stirring mechanism rinse mechanism 30 after the mixing. A transmissive-light measuring unit 31 measures the absorbance of the sample-reagent mix contained within the reaction vessel 3 while a scattered-light measuring unit 32 measures scattered light generated from the sample-reagent mix contained within the reaction vessel 3. All of the above operations including the measurement of transmissive light and scattered light are performed while the reaction disk 33 is being operated.
Number | Date | Country | Kind |
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2011-010349 | Jan 2011 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP2012/051117 | 1/19/2012 | WO | 00 | 7/16/2013 |