JPH11142326A - Absorptiometer for measuring glycohemoglobin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an absorptiometer simple in structure and sufficiently reduced in size and cost. SOLUTION: A light source 1 is a laser emitting blue light with a wavelength of 415 nm. An absorptiometer includes a light emitting system containing the light source 1; a sample cell 2 holding glycohemoglobin; a measuring light detection system consisting of a measuring photodetector 5 detecting the light passed through the sample cell 2 to convert the quantity thereof to a current, and of a measuring current/voltage converter 6 converting the current to voltage, and a measuring light path system guiding the light from the light source 1 to the sample cell 2 and guiding the light passed through the sample cell 2 to the measuring light detection system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorbance meter for measuring glycated hemoglobin.

[0002]

2. Description of the Related Art Glycohemoglobin is a substance in which glucose molecules are chemically bonded to hemoglobin in a non-enzymatic manner, and has conventionally been used clinically as a marker for diagnosing diabetes.

[0003] The concentration of glycated hemoglobin is usually measured by an absorbance meter. An absorptiometer is an apparatus that converts light from a light source into a single color, transmits the light through a sample solution, and converts the intensity of the transmitted light into an electric signal to measure the absorbance of the sample. When measuring glycated hemoglobin, since the maximum absorption wavelength of glycated hemoglobin is 415 nm, it is necessary to transmit light near the wavelength of 415 nm to glycated hemoglobin in the sample solution. Conventionally, when measuring glycated hemoglobin, an absorbance meter using a lamp light source such as a halogen lamp or a tungsten lamp as a light source has been used.

[0004] The light emission state of the lamp light source is greatly affected by changes in the external environment such as temperature. For this reason, parts for keeping the temperature around the light source constant are required, and the installation place of the light source is limited. Since the heat generated by the light source itself is large, the temperature inside the absorbance meter also increases. If a device for cooling the temperature of components and the like inside the absorbance meter is provided, the absorbance meter itself becomes large and expensive.

[0005] It takes a long time for the light quantity of the lamp light source to stabilize after the start of light emission. An absorbance meter for measuring glycated hemoglobin may require urgent measurement due to its clinical function, and is often kept powered on.
The lamp light source has a large change with time in the amount of light, and has a short stable lighting time of about 4000 hours. For this reason, it was necessary to replace the lamp frequently. In addition, since a large current is required to light the lamp, there is a restriction that the size of the drive circuit inside the absorbance meter must be increased.

[0006] The lamp light source includes not only light having a wavelength of 415 nm but also many lights having other wavelengths.
In order to transmit only light having a wavelength of 415 nm to glycohemoglobin, an interference filter that selectively transmits light having a wavelength of 415 nm is required. In addition, since a lamp light source has a heat ray at an emission wavelength, a heat ray absorption filter for removing the heat ray is required.

[0007] As described above, the absorbance meter for measuring glycated hemoglobin using a lamp light source requires many parts, and is therefore large and expensive. For this reason, in recent years, an absorbance meter using a light emitting diode (hereinafter, referred to as an LED) as a light source instead of a lamp light source has been used.

When an LED is used as a light source, it consumes less power than a lamp, generates less heat, and hardly increases the temperature inside the absorbance meter. No need. In addition, 415n
LEDs near m do not have a heat ray at the emission wavelength, so a heat ray absorption filter is not required.

[0009]

As described above, an absorbance meter using an LED as a light source has a simpler structure, a smaller size, and is less expensive than a device using a lamp light source. However, the LED includes not only light having a wavelength of 415 nm but also a plurality of lights having other wavelengths. Therefore, an interference filter was indispensable for transmitting light having a wavelength of 415 nm to glycohemoglobin.

[0010] The light emitted by the LED has low parallelism. Since accurate measurement requires parallel light to enter the interference filter and the sample cell, a collimator lens that converts light from the LED into parallel light is required. As described above, even if an LED is used as a light source, the absorbance meter cannot be sufficiently reduced in size and cost.

The present invention has been made in order to solve the above-mentioned problems, and has as its object to provide an absorptiometer for measuring glycated hemoglobin which has a simple structure, and is sufficiently reduced in size and cost. .

[0012]

The absorptiometer for measuring glycated hemoglobin according to the present invention, which has been made to achieve the above object, has a light emitting system using a laser emitting a monochromatic blue light having a wavelength of 415 nm or near the same as a light source. A light transmissive sample cell that holds a sample containing glycated hemoglobin, a light receiving system for measurement that receives light passing through the sample cell and converts the voltage, and guides light from the light emitting system to the sample cell, A measurement optical path system for guiding the light passing through the sample cell to a measurement light receiving system.

The laser light source has a single emission wavelength, has a very short time until the light quantity is stabilized, and has a long life as a light source. Furthermore, it is a light source that is resistant to impact, small in size and low in power consumption. Since the laser light uses stimulated emission, it has the same wavelength and phase, and is used for glycohemoglobin measurement.
It is possible to obtain light having a wavelength of only 15 nm.
Moreover, the light emitted from the laser light source does not include heat rays. Therefore, unlike the case of using a lamp light source, a heat ray absorbing filter is not required for the absorbance meter. Further, since the wavelength of the laser light is, for example, only 415 nm, there is no need for an interference filter for cutting light having a wavelength other than 415 nm. In addition, the power consumption of the laser light source is about 1/20 that of the lamp light source, and the heat generation is very small.

The laser light source may be a device capable of obtaining a wavelength of 415 nm by direct light emission, or a device capable of indirectly extracting 415 nm from another wavelength such as a waveguide type SHG. Since the peak of the absorption wavelength of glycated hemoglobin is 415 nm, the emission wavelength of the laser light source may be around 415 nm. Specifically, 400 to 450 nm may be used.

The light-transmitting sample cell for holding the sample containing glycated hemoglobin only needs to be capable of transmitting light from a light source, and a part of the sample cell is not transparent even if it does not have perfect transmittance. It doesn't matter. Specifically, the sample cell is desirably made of glass or plastic. The sample cell includes a rectangular parallelepiped cell and a tubular cell. The tubular cell is particularly preferably in the form of a flow cell in which a liquid continuously flows through a tube.

The measuring light receiving system comprises a measuring light receiving element for receiving light passing through the sample cell and converting the amount of light to a current, and a measuring current-voltage converter for converting the current to a voltage. These are not particularly limited, but specifically, photodiodes and photoelectric tubes are used.

The measuring optical path system guides light from a laser light source, which is a light emitting system, to a sample cell. Since the laser light has high parallelism, a collimator lens for converting light from a light source into a parallel light beam is unnecessary in the measurement optical path system in the absorbance meter of the present invention. A configuration in which the light emitting system, the sample cell, and the light receiving system are simply arranged on a straight line is sufficient. If they cannot be arranged on a straight line, an optical fiber may be used.

The absorptiometer for measuring glycated hemoglobin of the present invention comprises a control light receiving system which is a light receiving system different from the light receiving system for measurement, and a control light path system which is a light path system different from the light receiving system for measurement. The control light receiving system receives light from the light emitting system without passing through the sample cell and converts the voltage, and the control optical path system receives light from the light emitting system without passing through the sample cell. Preferably, the optical path system leads to a control light receiving system.

When a contrast light receiving system and a contrast optical path system are provided,
Glycohemoglobin can be easily and repeatedly measured under the same conditions, and the accuracy of the measurement can be improved.

The control light receiving system includes a control light receiving element for receiving light from the light emitting system without passing through the sample cell and converting the light amount into a current, and a control current / voltage converter for converting the current into a voltage. It becomes. The control light-receiving element and the control current-voltage converter may be the same as the measurement light-receiving element and the measurement current-voltage converter in the measurement light-receiving system. Alternatively, one light-receiving element and one current-voltage converter can be switched between measurement and control. In this case, the control optical path system itself is overlapped with the measurement optical path system, and the measured value in a state where no sample cell is arranged or a state where a sample cell not holding a sample is arranged may be set as a control value. .

If a control optical path system is separately arranged in addition to the measurement optical path system so as to guide light from the light emitting system to the control light receiving system, it is not necessary to pay attention to the arrangement of the sample cells. Therefore, it is preferable that the measurement optical path system and the control optical path system are separately arranged.

As a further preferred embodiment of the absorptiometer for measuring glycated hemoglobin of the present invention, a light source driving system for turning on a light source in a light emitting system, and an integration for integrating a voltage converted by a control light receiving system within an arbitrary time. There is a configuration having a comparator and a comparator that compares a voltage output from the integrator with a preset reference voltage and drives or stops the light source driving system based on the comparison result.

The comparator oscillates a signal for stopping the light source driving system when the voltage output from the integrator is higher than the reference voltage, and oscillates when the voltage output from the integrator is lower than the reference voltage. A signal for driving the light source drive system is oscillated. The light source is turned on or off by driving or stopping the light source driving system, and the light quantity guided to the control light receiving system is kept constant.

If the reference voltage can be controlled by a microcomputer or can be changed by a user, accurate measurement can be performed even when parts of the optical path system are replaced or when the light quantity changes with time. It can be performed.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a diagram showing an outline of an embodiment of an absorbance meter for measuring glycated hemoglobin according to the present invention. The light source 1 is a semiconductor laser that emits blue laser light having a wavelength of 415 nm. Blue laser light has high parallelism and a single wavelength. A sample cell 2 containing a sample solution containing glycated hemoglobin is disposed in front of the light source 1 (in the emission direction of the laser light 11), and behind the light source 1 (in a direction opposite to the emission direction of the laser light 11). Is provided with a lighting circuit 10 which is a drive system of the light source 1. The sample cell 2 is made of a light-transmitting plastic, and the light 1 that has passed through the sample cell 2
A photodiode 5a as a light receiving element for measurement is arranged at a position where 1a passes. Between the light source 1 and the sample cell 2, a beam splitter 3 for dispersing the parallel light 11 from the light source 1 is arranged. Above the beam spiriter 3, a photodiode 5b serving as a control light receiving element that receives the light 11b that has not passed through the sample cell 2 is arranged. The photodiode 5a is a current / voltage converter 6 for measurement.
a, the photodiode 5b is connected to a control current-voltage converter 6b. Current-voltage converter for measurement 6
a is connected to an analog-digital converter 7, which is connected to a microcomputer 8. The control current / voltage converter 6b is connected to the comparator 9 via the integrator 20, and the comparator 9 is connected to the light quantity setting circuit 15.

The operation of the absorbance meter for measuring glycohemoglobin according to the present invention will be described below with reference to FIG.

The laser beam 11 emitted from the light source 1 is split by the beam splitter 3 into beams 11a and 11b. The light 11a passes through the sample cell 2 and is incident on the photodiode 5a, and the light 11b is incident on the photodiode 5b.
The photodiodes 5a and 5b respectively emit light 11a and 11b.
The light quantity b is converted into a current, and the converted current is converted into a voltage by the current-voltage converters 6a and 6b. The voltage output from the measuring current-voltage converter 6a is input to the analog-to-digital converter 7 and converted into a digital signal. The absorbance is calculated by inputting the digital signal to the microcomputer 8.

The voltage output from the reference current-voltage converter 6b is input to the integrator 20, averaged and then input to the comparator 9. The comparator 9 compares the input voltage with a reference voltage preset by the light quantity setting circuit 15, and stops the lighting circuit 10 when the voltage output from the integrator 20 is higher than the reference voltage. Oscillate the signal. By stopping the lighting circuit 10, the laser light source 1 is turned off. As a result, the voltage output from the integrator 20 becomes lower than the reference voltage. The comparator 9 oscillates a signal for driving the lighting circuit 10, and the laser light source 1 is turned on by driving the lighting circuit 10.

The above operation is repeated, and the laser light source 1 is feedback-controlled while being pulsed, so that the amount of light guided to the control light receiving system is kept constant.

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and various modifications can be made within the scope of the claims described at the beginning. It is also possible. Even if each component is replaced with an equivalent, it does not matter at all.

[0032]

The absorbance meter for measuring glycated hemoglobin according to the present invention uses a laser as a light source, and therefore generates much less heat than an absorbance meter using a lamp as a light source. Since a radiator or the like having a large heat capacity becomes unnecessary, the entire absorbance meter can be downsized.

The light amount of the laser light source is stabilized in a short time from the start of light emission. Therefore, it is sufficient to operate the absorbance meter after the measurement of glycated hemoglobin, and it is possible to sufficiently cope with an urgent measurement.

The laser beam has a single wavelength. By using a laser for measuring glycated hemoglobin that includes only light having a wavelength of 415 nm as a light source, the absorbance meter of the present invention does not require an interference filter that selectively transmits light depending on the wavelength. Furthermore, since a laser beam having a wavelength of 415 nm does not include a heat ray, a heat ray absorption filter is not required.

The conventional absorbance meter requires an interference filter, and also requires a collimator lens for collimating the light incident on the interference filter and the sample cell. The absorbance meter of the present invention uses a laser light source. Since laser light has high parallelism, in the present invention, it is not necessary to convert the laser light into parallel light, and the collimator lens included in the conventional absorbance meter becomes unnecessary.

As described above, when a laser is used as a light source, a heat ray absorption filter, an interference filter, and a collimator lens are not required, so that the entire absorbance meter can be made smaller than a conventional one. Further, since the light amount is stabilized in a short time, it is possible to sufficiently cope with an urgent measurement of glycated hemoglobin.

[Brief description of the drawings]

FIG. 1 is a diagram showing an outline of one embodiment of an absorbance meter for measuring glycated hemoglobin of the present invention.

[Explanation of symbols]

 Reference Signs List 1 light source 2 sample cell 3 beam spiriter 5a, 5b photodiode 6a, 6b current-voltage converter 7 analog-digital converter 8 microcomputer 9 comparator 10 lighting circuit 11 laser light 15 light quantity setting circuit 20 integrator

Claims (4)

[Claims] 1. A light emitting system using a laser that emits blue monochromatic light at or near a wavelength of 415 nm as a light source, a light transmitting sample cell holding a sample containing glycohemoglobin, and light passing through the sample cell. A light receiving system for receiving light and converting the voltage, and a light path system for measurement that guides light from the light emitting system to the sample cell and guides light passing through the sample cell to the light receiving system for measurement. Absorbance meter for measuring glycohemoglobin. 2. A light receiving system for contrast, which is a light receiving system different from the light receiving system for measurement, and a light path system for contrast, which is another light path system different from the light receiving system for measurement. The light receiving system for light receives the light from the light emitting system without passing through the sample cell and converts the voltage, and the optical path system for control uses the light from the light emitting system for receiving light without passing through the sample cell. 2. An absorptiometer for measuring glycated hemoglobin according to claim 1, wherein the absorptiometer is an optical path system leading to the system. 3. A light source driving system for turning on a light source in the light emitting system, an integrator for integrating a voltage converted by the control light receiving system within an arbitrary time, and a voltage output from the integrator and 3. A glycated hemoglobin measuring device according to claim 1, further comprising: a comparator for comparing the set reference voltage with the reference voltage, and driving or stopping the light source driving system based on a result of the comparison. Absorbance meter. 4. The measurement light-receiving system includes a measurement light-receiving element for receiving light passing through the sample cell and converting the amount of light to a current, and a measurement current-voltage converter for converting the current to a voltage. The control light receiving system includes a control light receiving element that receives light from the light emitting system without passing through the sample cell and converts the light amount into a current, and a control current-voltage converter that converts the current into a voltage. The absorbance meter for measuring glycated hemoglobin according to any one of claims 1 to 3, characterized in that: