JP2001244483A - Light emission detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emission detector measuring precise light intensity with high measuring sensibility by eliminating the influence of static electricity given to a current/voltage conversion amplifier at the time of measuring light intensity using an optical sensor. SOLUTION: In a light emission detector measuring the light intensity of an inspection sample in a measuring container 14 by an optoelectronic multiplication tube and the optical sensor 6 of a semiconductor optical sensor, a part with which the measuring container 14 is brought into contact or to which it is brought close is constituted of metal and the other electric conductive material, and the part is electrically connected to the ground line of a current/ voltage conversion amplifier 10 connected to the optical sensor 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for detecting light emitted from a sample in a measuring container by chemiluminescence or biochemiluminescence, and more particularly, to accurately detect a small amount of light using a photomultiplier tube or a semiconductor photosensor. Luminescence detector.

[0002]

2. Description of the Related Art The measurement of chemical substances using chemiluminescence or biochemiluminescence can be performed at a very low concentration and can be carried out specifically for the purpose of measuring foods and pharmaceuticals. Is used in various fields. For example, according to a biochemiluminescence method using luciferase which is a firefly enzyme and luciferin which is a luminescent substance, adenosine triphosphate (A
The measurement of TP) has attracted attention in recent years as a method for measuring microbial contamination of foods and the like because the number of microorganisms can be calculated in real time.

[0003] In order to measure a chemical substance using such chemiluminescence or biochemiluminescence, a light emission detector for detecting extremely weak light generated from the light emitting substance is required. For example, a photomultiplier tube or a semiconductor photosensor is used. In the luminescence detector, when light from the specimen is irradiated on the optical sensor, a current corresponding to the light intensity is generated. This current is converted into a voltage by a current-voltage conversion amplifier connected to the optical sensor, and the voltage is converted to light. The strength is calculated.

[0004]

In an emission detector using an optical sensor such as the above-described photomultiplier tube or semiconductor optical sensor, the feedback of the current-voltage conversion amplifier is required to increase the light intensity measurement sensitivity. The resistance must be extremely high to increase the current-to-voltage conversion ratio.

[0005] However, if the current-voltage conversion ratio of the current-voltage conversion amplifier is increased in order to increase the measurement sensitivity, the current-voltage conversion amplifier is more susceptible to effects other than the current of the optical sensor, and is particularly susceptible to static electricity. For this reason, there has been a problem that an erroneous current such as an abnormal current or a noise current flows through the current-voltage conversion amplifier due to static electricity carried by the photodetector or the measurement container, and it is impossible to accurately measure the light intensity.

The present invention has been made in view of such a conventional situation,
It is an object of the present invention to provide a light emission detector capable of accurately measuring light intensity with high measurement sensitivity by eliminating the influence of static electricity applied to a current-voltage conversion amplifier when measuring light intensity using an optical sensor.

[0007]

In order to achieve the above object, the present invention provides a luminescence detector for measuring the light intensity of a specimen in a measurement container with an optical sensor. It is characterized in that a portion that is in contact with or in proximity to is made of an electrically conductive material, and that this portion is electrically connected to a ground line of a current-voltage conversion amplifier connected to the optical sensor.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS When measuring light intensity with a light emission detector using an optical sensor such as a photomultiplier tube or a semiconductor optical sensor, the light sensor detects light by acting on a current-voltage conversion amplifier. The static electricity that causes the generation of an incorrect current other than the current that flows when the sample container containing the sample is inserted into the luminescence detector is caused by the static electricity of the measurement container itself that contains the sample that is the luminescent sample. It turned out that the static electricity generated by the above is the main thing.

In particular, since the insertion hole for inserting the measurement container needs to shield external light, blackening treatment or anticorrosion treatment such as applying black paint on the inner peripheral surface is generally performed. Therefore, the conductivity of the surface is easily lost. Therefore, the static electricity of the measuring container itself and the static electricity generated at the time of insertion cannot be released, and this static electricity has an adverse effect on the optical sensor.

Therefore, in the present invention, the portion of the light emission detector to which the measurement container comes into contact with or in proximity to the light emitting detector is made of an electrically conductive material, and the portion made of this electrically conductive material is connected to the ground line of the current / voltage conversion amplifier. The connection prevents charging of static electricity, which causes an abnormal current such as an abnormal current or a noise current to flow.

Specific portions made of an electrically conductive material include, in addition to the above-described insertion hole of the measurement container, a holding portion of the optical sensor close to the insertion hole, and an abutment with the bottom of the measurement container in the insertion hole. There are parts. In addition, if there is nothing between the measuring container and the optical sensor, it is easily affected by static electricity. Therefore, conductive glass or conductive plastic, or metal ring or mesh (mesh) that transmits light to this part.
Is preferably connected to the ground line of the current-voltage conversion amplifier.

As the electrically conductive material, a metal material such as aluminum or copper can be generally used. However, depending on the constituent parts, conductive rubber or carbon, conductive glass or conductive plastic is used, or a part thereof is used. The member may be provided with a conductive paint or conductive plating.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the light emission detector of the present invention is shown in FIGS.
It will be described based on. In this light emission detector, as shown in FIG. 1, an insertion hole 2 is provided in a light-shielding case 1, and the insertion hole 2 has a step portion in the middle, and the entrance side 2a of the step portion has a small diameter and a bottom side. It has a large diameter. Inlet side 2 of insertion hole 2
a, a light-shielding lid 4 having a light-shielding packing 5a is provided so as to be openable and closable. The light-shielding lid 4 is engaged with the cylindrical body 3 fixed to the upper end of the inlet side 2a of the light-shielding case 1 to close the inlet side 2a of the insertion hole 2. It has become.

An optical sensor 6 composed of a photodiode is mounted below the stepped portion of the insertion hole 2 with a light path provided in the light shielding case 1 interposed between the light shielding case 1 and the periphery of the optical sensor 6. Is shielded from light by the light-shielding packing 5b. A current / voltage conversion amplifier 10 is connected to the optical sensor 6, and these are electrically shielded by a shield case 11. The current generated by the light sensor 6 detecting light from the specimen is converted into a voltage by the current-voltage conversion amplifier 10 and transmitted to the arithmetic unit 13 having a CPU and the like through the A / D converter 12. In the calculation unit 13, the optical sensor 6
The concentration of the sample corresponding to the light intensity detected in is calculated,
It is displayed or printed as desired.

A shutter 7 for closing the insertion hole 2 and shielding the optical sensor 6 from light is provided at a step portion of the insertion hole 2 so as to be movable by a spring 8. The shutter 7 includes a small-diameter cylindrical portion and a large-diameter cylindrical portion. Usually, the shutter 7 is pushed up by a spring 8 so that the small-diameter cylindrical portion fits into the small-diameter portion of the insertion hole 2 and comes into close contact with the light-shielding case 1 at the step. It is structured to prevent light from entering from. The measurement container 1 is inserted into the insertion hole 2.
When the shutter 4 is inserted, the spring 8 contracts and the shutter 7 moves to the bottom. Whether the shutter 7 is closed or open can be detected by the shutter detection sensor 9.

Next, a procedure for measuring the light intensity by the light emission detector will be described. First, as shown in FIG. 2, the sample solution 15 is put into the measurement container 12, the light shielding cover 4 is opened, the measurement container 15 is inserted into the insertion hole 2, and the light shielding cover 4 is closed. At this time, the shutter 7 is depressed, the light emitted from the sample solution 15 is detected by the optical sensor 6 composed of a photodiode, a current proportional to the light intensity is generated, and the current is converted into a voltage by the current-voltage conversion amplifier 10. The arithmetic unit 13 measures the sample concentration.

In this light intensity measurement, in order to increase the light intensity detection sensitivity, it is necessary to increase the feedback resistance of the current-voltage change amplifier 10 to increase the current-voltage conversion ratio and detect a minute current. is there. However, by increasing the current measurement sensitivity, the optical sensor 6 is more susceptible to effects other than the current, and in particular, the effects of external electrical induction and static electricity cannot be ignored. Electrical induction can be prevented by putting the entirety of the optical sensor 6 and the current / voltage conversion amplifier 10 in the shield case 11, but static electricity generated by the measurement container 14 and friction caused by friction can be prevented by the shield case 1.
It is impossible to prevent even by 1.

Therefore, in the light emission detector of the present invention shown in FIG. 2, the light-shielding case 1 (including the inner peripheral surface of the insertion hole 2) and the shutter 7 are both made of aluminum, and the spring 8 is made of stainless steel. , The shutter 7 and the spring 8 are all electrically connected to the ground line of the current-voltage conversion amplifier 10 and the shield case 11. In addition, a plate-shaped conductive member 16 made of conductive glass or conductive plastic that transmits light was arranged in front of the optical sensor 6 and connected to the ground line of the current-voltage conversion amplifier 10 and the shield case 11. In addition, the measurement container 1 in which the sample is to be placed.
4 is usually made of plastic or glass having high light transmittance.

Using the luminescence detector of the present invention, the voltage change of the current-voltage conversion amplifier 10 before and after the measurement container 14 (without the sample solution) was inserted into the insertion hole 2 was measured, and the results are shown in Table 1 below. Indicated. The voltage before the measurement container 14 was inserted was measured in a state where the light shielding cover 4 was closed and the external light was completely shielded.

For the purpose of comparison, the same measurement was performed for a case where the inner peripheral surface of the insertion hole 2 was coated with a black alumite plating made of an aluminum oxide film, and the obtained results are also shown in Table 1 below. Was. Incidentally, also in the case of this comparative example,
The light-shielding case 1, the shutter 7, and the like were electrically connected to the ground line of the current-voltage conversion amplifier 10 and the shield case 11, as in the case of the present invention.

[0021]

[Table 1]Emission detector Voltage change (mV)  Emission detector of the present invention 0 Emission detector of comparative example 126

In the above test, since the specimen solution that emits light is not contained in the measuring container 14, no current due to light detection flows through the optical sensor 6. However, in the case of the light emission detector of the comparative example in which black alumite plating having no electrical conductivity was applied to the inner peripheral surface of the insertion hole 2, an incorrect voltage of 126 mV was observed. Even in the case of the comparative example, since the light-shielding case 1 and the like are connected to the ground line of the current-voltage conversion amplifier 10 and the shield case 11, it is apparent that the light-shielding case 1 is not caused by an improper voltage generation due to external electric induction. Thus, it can be seen that the static electricity generated by the static electricity or friction of the measurement container 14 itself has an effect.

On the other hand, no voltage change was observed in the light emission detector of the present invention. As described above, according to the present invention, a portion where the measuring container 14 comes into contact with or in proximity to the measuring container 14 is made of an electrically conductive material, and is electrically connected to the ground line of the current-voltage conversion amplifier 10 so that the influence of static electricity is reduced. It is possible to prevent it.

In the above-described light emission detector of the present invention, the portion in contact with the measurement container such as the light shielding case 1 is made of a metal such as aluminum. The object of the present invention can be attained also by making the device from an electrically conductive substance and electrically connecting it to the ground line of the current-voltage conversion amplifier.

[0025]

According to the present invention, in an emission detector using a photomultiplier tube or a semiconductor optical sensor, it is possible to prevent the generation of an erroneous current due to static electricity and measure the emission intensity more accurately. Thus, a luminescence detector suitable for measuring chemiluminescence or biochemiluminescence can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic partially cutaway side view showing a specific example of a light emission detector of the present invention.

FIG. 2 is a schematic partially cutaway side view showing a state where a measurement container is inserted into the luminescence detector of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Shield case 2 Insertion hole 4 Shield cover 6 Optical sensor 7 Shutter 8 Spring 10 Current-voltage conversion amplifier 14 Measurement container 15 Sample solution 16 Conductive member

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kazuka Tanaka 613 Kitairiso, Sayama-shi, Saitama Toa Denki Kogyo Co., Ltd. Sayama Plant F-term (reference) 2G054 AA06 AB07 AB10 BA04 CA20 CA21 CA28 EA01 EA02 FA12 FA21 FA22 FA32 FA44 FA50 FB03 GA04 GB10 JA01 JA04 JA05 2G057 AA14 BA01 BB01 BB06 BC10 5F088 BA03 BA10 BB06 JA05 JA20 5G067 AA53 DA02

Claims (1)

[Claims] 1. A light emission detector for measuring light emission of a specimen in a measurement container by an optical sensor, wherein a portion of the measurement container in contact with or in proximity to the measurement container is formed of an electrically conductive material, and the portion is formed of the optical sensor. A light-emitting detector electrically connected to a ground line of a current-voltage conversion amplifier connected to the light-emitting device.