JPS5811859A - Dispensation detector - Google Patents

Abstract

PURPOSE:To precisely detect whether dripping is present or not, by detecting a drop by variation of luminous flux caused by a small amount of a drop falling from a dispensating nozzle crossing the luminous flux. CONSTITUTION:Two photodetectors 12 and 13 are arranged to photodetect each luminous flux 10 and 11 from luminous flux generators 4 and 5. A container 14 is so arranged that a drop 2 of a reagent after crossing those pieces of luminous flux 10 and 11 falls therein. When the drop 2 of the reagent falls in the container 14, it crosses those pieces of luminous flux 10 and 11, so the photodetectors 12 and 13 vary in the quantity of photodetection and output signals appear at output terminals 15 and 16 when the drop 2 cross the pieces of luminous flux 10 and 11. One of those signals is delayed and those signals are ANDed to obtain bit drop detection signal.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a dispensing detection device of a frequently used analytical dispensing device, particularly to a drip detection device Q.

In dispensing devices in the field of biochemistry, sample samples are also trending toward miniaturization.

Therefore, the discharge of reagents or samples from the dispenser becomes like a drip, and as the discharge volume decreases, the tip of the dispensing nozzle also becomes smaller. There is a risk that clogging may occur and dispensing may not be performed at all.

In particular, automatic analyzers move to different analysis steps one after another, so if a situation occurs where no dispensing occurs, subsequent steps will continue to be invalidated. Conventionally, when a dispensing pump is clogged, if the volume to be dispensed is large, it is detected using a pressure gauge that detects the abnormal pressure caused by the clogging when pressurizing, but this is not an abnormality detection. However, there is a drawback that normal operating conditions cannot be detected.

The present invention solves such drawbacks and provides a dispensing detection method suitable for use in an automatic dispensing device, which is capable of detecting the presence or absence of a minute droplet from a dispensing nozzle with a good S/N ratio. We would like to provide the equipment. That is, the present invention provides a dispensing device for chemical or biochemical analysis, in which a light generating device including a light source and a photodetector that receives the light from the light flux generating device are connected to a minute droplet dropped from a dispensing nozzle. The drip is detected by a change in the luminous flux caused by the minute droplet crossing the luminous flux.

The present invention will be described in detail below based on examples.

FIG. 7 shows the configuration of an embodiment of the present invention, in which figure A is a block diagram of the photodetector, and figure B is a block diagram of the output signal processing unit from the photodetector. It is a diagram. In the same figure A, / is the tip of the dispensing nozzle, C is a reagent pump (not shown), which is a reagent part that is a small amount of droplets guided from a reagent reservoir, and 3 is a falling path through which the reagent part drips.
t and S are two sets of optical generators including a light source B, 7 and a lens 9 for forming a beam from the light source 4.7, and lθ and /7 are respective optical generators. +, the luminous flux from 1, and these laurels lθ, /
/ indicates that each of the light flux generating devices is arranged so as to intersect the falling path 3 of the reagent part 3 at an appropriate distance d. Further, 12 and 13 are two sets of photodetectors arranged to receive each of the light fluxes lθ, /) from the light flux generators @p, s, respectively, and /'/ is a reagent from the dispensing nozzle/. The reagent portion 2 is arranged so that the reagent portion 2 is dripped into the container after each of the light beams lθ, // intersects.

In such a configuration, when the reagent part falls into the container /l, it intersects each light beam lθ, //, so the amount of light received at each photodetector /2, 13 changes, and each output terminal /1
From 3 and /4, the reagent section 2 has a respective luminous flux lθ.

An output signal is obtained at the time when // intersects.

Figure B is a circuit configuration diagram for processing the output signals from the photodetectors /2 and /3, and these output signals are transmitted from the input terminals /7 and 1g to the respective level detectors /9. ,．． Added to 21!7. Each level detector/
I.

Reference numeral 19 is composed of, for example, an amplifier and a Schmidts rigger circuit, and is configured to convert changes in the output signal of each optical analyzer/fl detector, which changes as the reagent part crosses the light beam, into a pulse signal and output the pulse signal. It is composed of:

Hereinafter, for convenience of explanation, the light beam lθ that first intersects after the reagent part falls will be called the first light beam, and the light beam l/ that intersects after passing the distance d will be called the first light beam. The pulse signal from the level detector/l that detects the output signal of the photodetector/2 that receives the first light beam is sent to the delay circuit I.
For example, by means of a monostable multivibrator, the distance @
d is delayed by a time corresponding to the time when the reagent solution finishes passing through. If the pulse signal delayed in this way and the pulse signal from the level detector obtained by detecting the change in the second luminous flux are led to an AND circuit n and the logical product of both pulse signals is taken, a trace amount can be obtained. A minute droplet detection signal with high detection accuracy can be obtained from the droplet detection signal output terminal n.

In the present invention, the signal obtained when the reagent part 2 crosses the light flux is as follows:
This is based on the fact that a portion of the light is reflected and scattered by the reagent portion, so that the amount of light received by the photodetector is reduced by the period during which the light beam is passing through the reagent solution.

Therefore, the ratio of the circular area of the cross-sectional area of the luminous flux before passing and the cross-sectional area of the reagent part as a sphere corresponds to the dynamic range of the output signal of the Habo photodetector. Making them equal is effective in increasing the dynamic range.

However, in order to ensure that the reagent part intersects with the light beam, it is common to make the cross-sectional area of the four light beams larger than that of the reagent layer. In relation to positioning accuracy, it is necessary to make the light beam a little thicker, but from the viewpoint of safety, it is appropriate to set the ratio of the cross-sectional area of the reagent layer to the cross-sectional area of the light beam to be 5θ% or less.

The basic configuration of the present invention is to detect a trace droplet (number m) using the output of only one of the level detectors 19 and The falling path of layer 3Q is an appropriate distance d
Two light beams lθ, // are arranged with a distance between them, and each photodetector /J crosses both light beams.

In the case where the temporal correlation of the output of /A is used, it is possible to prevent the influence of noise caused by, for example, a foreign object blocking the light flux, so that the trace droplet detection signal is significantly improved. Particularly in automatic dispensing machines, if a malfunction occurs due to noise as mentioned above, it may affect the next subsystem, and this may lead to system destruction. A highly accurate test device is required. On the other hand, the above-mentioned embodiment fully satisfies this requirement, but
If it is necessary to further increase the detection accuracy, the minute droplet detection signal may be obtained by a signal processing circuit having the configuration shown in the block diagram in FIG.

In the figure, /9 and 26 are the same as the level detectors in FIG. 1B. That is, as explained earlier,
Each of them is composed of an amplifier 24', B and a Schmitt trigger circuit C, 27. Also, the delay circuit l
is composed of two monostable multivibrators 29 and 3θ for delaying the pulse signal detected by the level detector 19 by different times. One of the monostable multivibrators 2 is such that the reagent droplets from the dispensing nozzle are in the first luminous flux 10 shown in FIG.
The second monostable multivibrator 3θ has an output with a polarity opposite to that of the monostable multivibrator 3θ. , the reagent layer 2 has a delay time T corresponding to the time from the first light beam lθ shown in FIG. 1A to just before it intersects with the first light beam. The skewer pulses from each of these monostable multivibrators, 3θ, and a level detector to which the output of the photodetector 12 that receives the first light beam is supplied are led to an AND circuit 3/, and their respective outputs are The AND output of the pulses is extracted and used as a trace droplet detection signal.

FIG. 3 shows the time relationship of each of these output pulses, and A is obtained by detecting the change in the output level of the photodetector 12 for the first light beam using the level detector tq < Indicates an output pulse signal, B is a delayed signal delayed by the delay time T by the monostable multivibrator 29 driven by the output pulse signal, and 0 is a monostable multivibrator 29 driven by the pulse signal shown in A. This is a delayed signal obtained by delaying the time of T2 by the multivibrator 3θ. Further, D is an output pulse signal from the level detector which receives all the output signals of the photodetector 13 which receives the second light beam, and this output waveform is maintained for the time TAD during which the reagent layer passes through both light beams. The trace droplet detection signal is obtained at a timing that is delayed from the waveform.

As is clear from the waveform diagram in FIG. 3, according to this embodiment, detection is performed during the period T3 from just before the reagent layer intersects with the second light beam until it finishes passing through the first light beam. As a result, detection accuracy is further improved.

Now, if the amount of reagent to be dropped is 12.5μl, the direct diameter φ of the droplet is approximately 12.5μl, and the distance from the position of the reagent droplet at the tip of the dispensing nozzle to the light T#, lθ of @/ If the distance to the second luminous flux is 10, and the distance to the second luminous flux is %, then the initial velocity of the reagent layer 2 is zero, and the first luminous flux lθ crosses the first luminous flux lθ and the intersecting time teva, 0.0/ -4x9Jxt'e,
t,-0,OII! ; 880, the time t2 until it intersects with the second beam l/ is)0-0u-4×9 J X
t2J: '), %-0-O631rsea,
The time TA required to pass the distance d between both luminous fluxes lθ and 11
D is approximately /9 msec.

Now, assuming that external vibration is applied to the dispensing nozzle and an initial velocity is applied to the reagent layer, the initial velocity is 10 m/Se.
c, it is 1 cm/mB, so the reagent drop 2
The time when the light crosses the first beam // is 7 mF3 earlier.

Therefore, in order to be able to sufficiently detect such a situation, the rear end of the waveform shown in Figure 3G should be further adjusted by /ms.
Just make it shorter.

Even if the reagent droplet had a negative or upward initial velocity, it would be extremely small, and even if it had a positive or downward initial velocity, the damping effect of the liquid would cause the actual dispensing nozzle to The initial velocity given by the vibration is so small that it can be almost ignored. Furthermore, the delay times T and T2 of the delayed pulse signals shown in B and C in FIG.
To make the time difference T3 as small as possible so that the D waveform obtained by the light amount change G is included without fail,
These times T□ and T2 are necessary to improve detection accuracy, and these times T□ and T2 may be determined experimentally.

In the embodiment shown in FIG. 2, the detection judgment output obtained as described above is sent to the counter 32 to obtain information for sample verification accompanying the processing of multiple samples in the automatic analyzer. This also prevents the system from running out of control. In FIG. 2, 33 indicates a reset pulse input terminal, and 39 indicates a counter output terminal.

FIG. 1 shows the configuration of another embodiment of the photodetector according to the present invention.

In the case shown in FIG. 1B, two luminous fluxes lθ,
Each of the two luminous flux generating devices & and It is constructed so that two light beams are formed at two locations separated by an appropriate distance d on the falling path of a reagent droplet dropped from /.

That is, the luminous flux from the Koei starting device M3S is divided into two by the mirror 3B, one of which is received as the first luminous flux 10 by one of the photodetectors/J, and the other divided luminous flux is separated into two parts. The light beam is guided to a mirror n, and the mirror n causes the light beam to enter another photodetector lB as a second light beam l/.

The output signal from each photodetector /J, /4 is processed by the signal processing circuit shown in FIG. 1B or FIG.
It is sufficient to obtain a minute droplet detection signal, and since these effects have been explained earlier, their explanation will be omitted here. However, in this example, since the output signal of the photodetector 16 also changes when the minute drop crosses the first light beam, it is necessary to nullify this signal change. As is clear from the above explanation,
According to the present invention, it is possible to automatically detect the presence or absence of instillation of a small amount of droplet from a dispensing nozzle, which was conventionally done by human eyes, with a relatively simple configuration, and it is also possible to achieve sufficiently high detection accuracy.
It is extremely effective for use in a dispensing detection device of an automatic analyzer.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the embodiment of the present invention, FIG. 2 is a block diagram showing the structure of another embodiment of the signal processing section of the present invention, and FIG. 3 is the signal processing shown in FIG. 1. FIG. 4 is a waveform diagram for explaining the operation of the photodetector section, and is a configuration diagram of another embodiment of the photodetector section in the present invention. l... dispensing nozzle tip, c... reagent drop, 3...
・Reagent droplet falling route, 5, 35...Light flux generator, B. 7...Light source, J, q...Lens, lθ, //...
Luminous flux, /2. 13...Photodetector, /'l...Container, /3, /
4... Output terminal of photodetector, /7, 1g... Level detector input terminal, tq, x... Level detector, u
, 21! ...Delay circuit, 22, 3/...AND
Circuit, 3... Trace drop detection signal output terminal, 2! , 2
5... Increase 111j [J, 27... Schmitt trigger circuit, Δ. 3θ...monostable multivibrator, 32...counter, 33...reset pulse input terminal, 3ri...
・Counter output terminal, 3 Otsu 1. ? 7...Mirror. Figure 1 Figure 3 Figure 4 349-

Claims (1)

[Scope of Claims] 1. In a dispensing device for chemical or biochemical analysis, a light flux generating device including a light source and a photodetector that receives the light flux from the light flux generating device are connected to a small amount dropped from a dispensing nozzle. A dispensing detection device, which is arranged in such a relationship that the falling path of the droplet intersects the luminous flux, and detects an infusion by a change in the luminous flux caused by the minute droplet crossing the luminous flux. 2. The falling path of the minute droplet is made to intersect the light beam at two points separated by an appropriate interval, and each light beam passing through each of these intersections is received by a separate photodetector, so that the minute droplet is The output signal from one of the photodetectors obtained by crossing the first intersection is delayed by the time it takes for the microdroplet to pass between the intersections at the λ points, and this delayed signal and the microdroplet Dispensing detection according to claim 1, characterized in that the AND output with the output signal from the other photodetector obtained by crossing an intersection later passed through is used as the minute droplet detection signal. Device.