GB2606276A

GB2606276A - Particle analysis device and particle analysis unit

Info

Publication number: GB2606276A
Application number: GB2206920.7A
Authority: GB
Inventors: Tatewaki Yasuhiro; Izawa Momoka
Original assignee: Horiba Ltd
Current assignee: Horiba Ltd
Priority date: 2019-10-15
Filing date: 2020-10-06
Publication date: 2022-11-02
Anticipated expiration: 2040-10-06
Also published as: GB202206920D0; GB2606276B; JPWO2021075310A1; WO2021075310A1

Abstract

To provide a particle analysis device capable of repeatedly switching the light on and off in a short time and capable of applying a constant current to an LED when it is turned on, with an inexpensive configuration with the overall device compact kept compact, the particle analysis device that analyzes properties of particles from an image obtained by capturing an image of the particles comprises: an LED that emits light to particles in a cell; a constant current circuit that applies a constant current to the LED; and a switching device that is connected to the constant current circuit and that turns current flowing to the LED on and off, wherein the constant current circuit includes: a measurement device that is serially connected to the LED and that measures the current flowing to the LED to output measurement signals; a shunt regulator that outputs feedback signals on the basis of the measurement signals; and a current control device that controls current flowing to the LED by using feedback signals.

Description

DESCRIPTION

PARTICLE ANALYSIS DEVICE AND PARTICLE ANALYSIS UNIT

Field

[00011 -the present Mention relates ba particle analysis device that analyzes the characteristics of particles from an image obtained by finaging the particles. and to a particle analysis unit including the particle analysis device,

Background

[00021 As illustrated in Patent Literature 1, this type of particle analysis device include a light-emitting diode (LED) that emits light to particles in a cell, and may be configured to repeatedly turn the 1,111D on and off to image the particles in the cell when the LED is turned on.

[0003; In such a configuration, first of all. in order to imat.e the contour of the ticles vi Mum, blurring, the on-lime must be short, Ibr example, several us. "then, in c match the imaging conditions of on-times, the brightness at each on-time must be constant. For this purpose. a constant current circuit including an operational ampl tor example, is nsed to apply a constant current to the LED.

[0004] [o ever. when such a constant current circuit is used and aninexpensive operational amplifier is used, the rise of the current when the LED i turned on is slow, making it difficult to turn the I.ED on and off in a short period of time. [fan expensive operational amplifier is used, for example. and a DC/DC converter is used to operate the device siith both pimer supplies, the constant current circuit becomes large and the Ns hole device becomes a large scale.

Citation List Patent Literature [00051 Patent I.iterature * U.S.Pa it Application P a 2017/0315039

Summary

Technical Problem 0.1006.1 1ihe present invention has been made to solve the above problems. and its main object is to make it possible to repeat the turning on and off clan LED in a short period of time and to apply a constant current to the LEI) durina the on time. while keeping the entire device compact and with an inexpensive configuration.

Solution to Probl-n Thus, a particle analysis device according to the present invention is a particle analysis device that analyzes a characteristic of particles from an image obtained by imaging the particles. The device includes: an 1.ED that emits light to the particles: a constant current circuit that flov.s a constant current to the LED: and a switching element that is connected 10 the constant current circuit and turns on and MI the current flowing through the LED. The constant CUITCtli Ciletlit includes: a measurement element that is connected in stifles 'AIM the LED. measures the current flowing through the LED, and outputs a measurement signal: a shunt regulator that outputs a feedback signal based on the measurement signal; and a current control element that controls the current flov)ing through the LED by the feedback signal.

[00081 With the pa dicle analysis device configured in this way. since a feedback circuit formed by the shunt regulator is used as the constant current circuit, the configuration can be made less expensive than that of im operational amplifier. In addition, since the shunt regulator can be operated by a single power supply. the entire device can be kept compact, and while the k ED is turned on and off repeatedly it) a short period of time, a constant current can be applied to the LED during the on time.

[0009.1 mote 'dile implementation, a configuration ma:), be provided, in which the shunt regulator includes: a control terminal that is connected to an anode side of the measurement element and receives an input of the measurement signal: and an output terminal that outputs the feedback signal and is connected to a control terminal of the current control element, and a resistive element having a predetermined resistance value is connected between the output terminal of the shunt regulator and the control it:Mina] current controi element.

With such a configuration, when the voltage measured by the 111CaSUECIllent. element increases, the voltage output from the shunt regulator (i.e., the voltage on the cathode side of the shunt regulator) increases and the current flow ing through the resistive element decreases. causing the current flow ing through the current control element, that is, the current flowing through the LTD to decrease. On the other hand. when the voltage measured by the measurement clement decreases, the voltage output from the shunt regulator {i.e., the voltage on the cathode side of the shunt regulator) decreases and the current flowing through the resistive element increases, causing the current flow ing through the current control element, that is. the current flowing through the LED to increase. This configuration enables feedback control of the current flowing through the LED to be a constant current. 01

ft) keep the voltage needed to drive the switching element low, it is pr rattle that the cathode side of the switching element is at ground potential. WO I 11 It is prc;terable that the switching element is connected in series with the LED. this conligtiration allows the LED to be switched on and off faster than when the switching element is connected in parallel with the LED, I 2.1 It is preferable that the particle analysis device further includes a resistive element that is connected in parallel with the LED and has a resistance value smaller than a resistance value of the LED when the constant current is flowing through the LED.

With such a configuration, immediately after the LED is turned on-from on, the current does not flow through the LED but through the resistive element, thus enabling the prevention of afterglow generation.

[00131 It is preferable that a voltage divider circuit is provided between the measurement element and the shunt regulator, and at least one of voltage divider resistive elements included in the voltage divider circuit is a variable resistive clement w ith a variable resistance value, With such a configuration, the size of the constant current floiving through the LED cart he adjusted by changing the resistance value oldie variable resistive element, tool 41 As an aspect in which advantageous effects of the present invention more conspicmously demonstrated, a configuration may further include an imaging device that images the particles" in which a cell housing the particles. the LED, the constant current circuit, and the imaging device are unitized and configured to be attachable to and detachable from a device body, With such a conflguratiott, since the part ic le analysis dcv ice ae cording to the present in is compact as described above, the device body to and from which this particle armlysis device is attached and detached can also be made compact, 0015f A particle anal) 515 unit including the particle analysis device and the device body described above is also One aspect of the present iimention, in V. Itch the device body includes a pairielc size distribution measurement device and an cite Insure hOnSing the particle size distribution measurement device, and the particle analysis device is housed in the enclosure together »iith the particle size distribution measurement device, In addition to the advantageous effects of the particle analysis device described above. such a particle amalysis unit can exert the effect of providing an image-based particle analysis device and a particle size distribution measurement device as a compact unit.

[00161 In order to further make the device hod) compact, it is preferable tliat the power supply of the device hod) is also used as a power supply to power the LED.

Advantageous Effects of Invention 1.00171 According to lhe i nvetiti on described above, it is possible to repeat the turning * on and alt at the 1.14I) in a short period c.,1 time and to apply a constant current lathe 1.14D during the on time. while keeping the entire device compact and VS ith an inexpensive configuration.

Brief Description of Drawing au

FIG. 1 is a schematic diagram °fan overall cantiat rticle analysis unit according io an embodiment.

FIG. 2 is a schematic diagram ala configuration at a particle is dcvi the embodiment FIG. 3 is a circuit diagram ala configuration of a drive circuit in the embodiment.

FIG. 4 is a circuit diagram ala conhiguratian ala drive circuit in another en bodiment FIG. 5 is a circuit diagram ala ci ligui ion ala drive circuit in another embodiment.

Reference Signs List 100 I 9] particle analysis unit 101 device body I circulation flow, path p circulation pump particle size distribution measurement device 31 cell 32 light source 33 photodetector 34 arithmetic device 40 enclosure particle analysis device 21 cell 22 LED 23 drive circuit 1 constant current circuit I I measurement clement 12 shunt regulator 12 control terminal 122 output terminal 13 ctarent control element 131 control terminal 2 switching, element gate drive circuit 4 first resistive element second resistive element 24 iiiititiiii system 241 imaging device 242 condensing lens 243 light-slueldinn Iiorisiin Inember 26 casing information processing device V power supply

Description of Embodiments 100201

An embodiment Mahe present invention is described below with reference to the drawings.

<Overall configuration of particle anal N sis unit 100> A particle analysis unit 100 according to the present embodiment analyzes various physical properties of particles. As illustrated in FIG. I, the particle analysis unit 100 includes a device body 101 and an image-based particle analysis device 20 that is attachable to and detachable from the device body 101.

[00221 <Device body 101> First. the following briefly describes the device body 101.

As illustrated in FIG. 1, the device body 101 in the present embodiment includes a particle size distribution measurement device.30 that measures particle size distribution and an enclosure 40 that houses at least a part oldie particle size distribution measurement device 30. The particle size distribution measurement device 30 measures particle size distribution based on a static light scattering tlictory. 100.23] Specifically, this particle size distribution measurement device 30 utilizes the fact that the light intensity distribution corresponding to the spreading angle of diffraction/scattering light generated when light is emitted to particles is determined by the particle size based on the MR'. scattering theory. The particle size distribution measurement device 30 includes a cell 31 that houses the particles, a light source 32 that emits light to the particles in the cell 31, photodelectors 33 that receive diffraetedlscattered light generated by the light emission, and an arithmetic device 31 that calculates the particle size distribution by acquiring a light intensify signal of the received light. Ilere. the cell 3L the light source 32, and the photodeteetors 33 are housed in the enclosure 30. In order to allow the cell 31 to be attached and detached without interfering with the optical system, a cell housing space is provided in this enclosure 40 where the cell 31 is placed. separated from the light source 32 and the photodetectors $3.

Here, as the cell 31 described above, a flow type cell in which a dispersion medium containing dispersed particles circulates is used. -1'he device body 101 in the present embodiment further includes a circulation flow path roc circulating the dispersion medium and a circulation pump P provided on the circulation flow path. These circulation flow path and circulation pump P are housed in the enclosure 10 described above. Alternatively, a batch type cell may be used for the cell 31 [0025] <Particle analysis device 20> The following describes the particle analysis device 20.

the particle atmlysis device 20 analyzes the characteristics of particles and measures physical property values that indicate the physical properties of the particles.

Specific examples of the physical property values include particle site (equivalent area diameter), aspect ratio, major axis length. minor axis length, maximum distance, circumference. area (measured in unt2). area (pixels: number of pixels in a particle). roundness, convexity, flatness, intensity of imaging pixels, particle size distribution. and aggregation rate.

10026l As illustrated in FIGS. I and 2, this par icleanalsis device20 includes a cell 21 that houses particles, an LED 22 that emits light to the particles in the cell 21, a drive circuit 2$ that lights the LEE) 22, an imaging system 24 that images the particles in the cell 21, and an in processing device 25 that analyzes the characteristics of the panicles from an image obtained by the imaging system 24. [00271 In the present embodiment, as illtistratcd in FIG. 2. among the above-described components, the cell 21, the LED 22, the drive circuit and the imaging system 24 are unitized, and they are configured to be integral Ft attachable to and detachable from the above-described device body I 01. Specifically, the cell 2 I. the I. ED 22, the drive circuit 23. and the imaging system 24 are housed in a single casing 26. and the casing 26 is attachable to and detachable from the device body 101. As a result, at least some components of the particle analysis device 20, specifically the cell 21. the LED 22, the drive circuit 23, and the imaging system 24. together with the panicle size distribution measureinent device 30 described above. are housed ill the enclosure 40 of the device body 101, and more specifically in the above-described cell housing space provided in the enclosure 40. The cell 21 may be configured to be attachable to and detachable from the casing 26, In this panicle analysis device a part of the drive circuit 23 is unique. Thus.

in the Milo)) ing, the components other than the driye circuit 23 '1, ill be described first, and then the drive circuit 23 Will be described. [00291 The cell 21 is a now type cell in which the dispersion medium containi dispersed particles circulates, as illustrated in FIG. I. and is installed in a circulation circuit I. described above in the present embodiment. Alternatively, the cell 21 may be located in a different circulation Uvula 1. than the circulation circuit L described above, or it Ma?, be a batch type cell.

The LED 22 emits I Edit when power is supplied but a power supply V. such as a constant voltage source. The LED 22 is a %lithe LED, ha example. In the present embodiment, a single 1.ED 22 is used, but a plurality of LEDs 22 connected in series or parallel with each other may be used instead. It is preferable that the power supply V ol the LED 22 is also used as a power supply V of the device body 101. such as the power supply V olthe particle site distribution measurement device 30 illustrated in FIG. I (the power supply of the arithmetic device 34) and as the power supply or the circulation pump P not illustrated in the drawings. Alternatively, the power supply V of the I.ED 22 may be provided separately from the power supplies of the device body 101 rhe iMMthigsystem 24. as illustrated in Fla 2, includes at least an imaging device 241 such as a camera. Here. the imaging system 24 further includes a condensing lens 242 that condenses the light having passed through the cell 2 t, and a housing reflect we member 243 such as a lens barrel that houses the condensin s and at least an entrance lens of the camera.

[0032] In the present embodiment, a shutter' oldie imaging device 241 is left open. When the LED 22 is lit, the light emitted from the LED 22 passes through the cell 21 and is guided to an imaging element of the imaging device 241. and an image of the particles in the cell 21 is acquired. The shutter of the imaging device 241 does not necessarily need to be left open, and may be opened and closed at predetermined timing, (time interval).

Pro, sically speaking, the information processing device 25 is a n 1-purpose or dedicated computer including a central processing unit (CPU). a mentors, an input/output interface, and other components. The intbrmat ion processing device 25 causes the CPU and peripheral devices to work together according to a predetermined program stored in a predetermined area of the memory so as to acquire image data of the particles obtained by the of the particles based on this image data, a predetermined physi 100341 The follr islrg ci pecifically. by image processing one or more ii property value is calculated and output.

aging device 211, and to calculate various charac ving describe he drive circuit 23, As illustrated in FIG, 3. the drive circuit 23 is configurec to repcatedls supply and stop power from the above-described power supply V to the I.ED 22, so that the lighting time and the olitime of the LED 22 are repeated at predetermined time intervals. Specifically, the drive circuit 23 includes a constant current circuit I that flows a constant current to the LED 22, and a switching element 2 that is connected to the constant current circuit I and turns on and otrthe current flowing, through the LED First, the thllowing describes the switching element 2. As illustrated in FIG. 3. the switching element 2 is conticeted in series with the LLD 22 and the constant voltage circuit to switch between on and off states. The sw itching clement 2 here turns on and olIthe connection bets\ eon ground potential and the constant voltage circuit, and the cathode side is at ground potential.

[00361 This switching element 2 is controlled so that the time in the on state and the time in the off state are each repeated at predetermined time intervals. Specifically, the switching; element 2 is a metal-oxide silicon field-effect transistor (MOSLEY) to which a gate signal is input from a gate drive circuit 3. for example. As a result, in the on state of the sw itching element 2, power from the power supply V is supplied to the LLD 22 and the TED 22 lights up, and in the offslate oldie sss itching clement 2, the power supply to the LED 22 is cut MT and the LED 22 turns off For example, a transistor may be used as the switching clement 2, [00371 In the pre embodiment, a first resistive element 4 hating a predetermined resistance value is connected in parallel with the LED 22 to prevent a current from flowing through the LED 22 and causing afterglow %Shen the LED:: is turned oil by turning the switching element 2 from the on state to the off state. More specifically, this first resistive element 4 la s a resistance value that is smaller than the resistance value of the LED 22 when a constant current supplied by the constant current circuit I described below is flowing through the TED 22.

[00.381 Thus, the constantt circuit 1 of the present embodiment includes a measurement element I I that measures the current flowing through the LED 22 and outputs a measurement signal. a shunt regulator 12 that outputs a feedback signal based on the measurement signal. and a current control element 13 that controls the current Ilowing through the LED 22 by the feedback signal. *The term "outputs a feedback signal based on the measurement signal" includes not only the case where the feedback signal is generated and output from the measurement signal itself but also the case where the feedback signal is generated and output from another signal obtained from the measurement signal.

[00391 Illte measurement e lenient tI is an element to detect the current flowing through the LEE) 22, and is connected in series with the EU/ 22. Specifically, the measurement element I I is a resistive element connected to the anode side of the switching element 2 described above and having a predetermined resistance value, 10040] The shunt regulator 12 includes a control terminal 12 i that is connected to the anode side of the measurement element II and receives the measurement signal, and an output terminal 122 that outputs the feedback signal and is connected to a control terminal 131 of the current control element 13. The shunt regulator 12 is operated by a single power supply. The feedback signal here refers to a signal that is adjusted by returning u voltage value output from the output terminal 122 of the shunt regulator 12 to the control terminal 121 so that the voltage value becomes a constant value.

[0011j To explain nuire specifically, a signal indicating the voltage on the anode side of the measurement element I I or the value of the current flow ing through the anode side of the measurement clement I I is input to the control terminal 121 of the shunt regulator 12 as a measurement signal. A signal indicating the value of the voltage corresponding to the measurement signal described above is output from the output terminal 122 of the shunt regulator 12 as a feedback signal. Here, a signal indicating the voltage value obtained by adding a predetermined voltage to the)(shape on the anode side of the measurement element tI is output from the output terminal 122 as the feedback signal.

The current control element 13 causes a current to flow through the LI according to the feedback signal input to the control terminal 131. and is a transistor. fbi example. Specifically, this current control element 13 is a negative-positive-negative (NPN) transistor including the collector terminal connected to the cathode side of the 22. the emitter terminal connected to the anode side of the measurement element I. and the base terminal, which is the control terminal 131, receiving, as base voltage, an input of the feedback signal, that is, the voltage value output from the output terminal 122 of the shunt regulator 12. Various types of current control elements, such as a PNP transistor and a ficld-ellect transistor (TiElf, may be used as the current control element 13. (I:1) lere. in the present enihod iment, a second resistive element 5 having a predetermined resistance value is connected between the output terminal 122 of the shunt regulator 12 and the control terminal 131 °lithe current control element 13. "Iiihe anode side of this second resistive element 5 is Colulected to the potver supp1y V. which is a constant voltage source in the present embodiment. As a result, a current corresponding to the difference between the constant voltage from the constant voltage source (25V in the present embodiment) and the voltage output from the output terminal 122 of the shunt regulator 12 flows through the second resistive clement 5. the anode side of the second resistive element 5 does not necessarily need to have the constant voltage (tithe constant voltage source applied to it: fbr example. a voltage lower than the constant voltage may be applied to it.

With such a con figura W. hen the voltage measured by the measurement element II increases, the voltage output from the shtmt regulator 12. that is. the voltage on the cathode side oldie shunt regulator 12. increases and the difference between this voltage and the voltage of the constant voltage source decreases, causing the current flowing through the second resistive element 5 to decrease. This reduces the current flowing from the second resistive element 5 to the current control element 13, thus reducing the current flow ing through the current control element 13_ or the current flowing through the LED 21.

[0015] On the other hand, when the voltage measured the measurement e lenient I1 decreases_ the voltage output from the shunt regulator 12, that is, the voltage on the cathode side oldie shunt regulator 12, decreases and the difference between this voltage and the voltage of the constant voltage source increases, causing the current flowing through the second resistive element 5 to increase. "This increases the current flowing front the second resistive element 5 to the current control element 13, thus increasing the current flowing through the current control element 11, or the current flowing through the lirD 22.

Thus, in the constant current circuit 1 of the present embodiment, circuit is formed by the shunt regulator 12, and this feedback circuit enabl control oldie current flowing, through the LLD 22 to be a constant current.

10047] In addition, in the present embodiment, a voltage divider circuit 6 is provided between the measurement element 11 and the shunt regulator 12. "the voltage indicated by the measurement signal measured bv the measurement element 11 is divided by the voltage divider circuit 6. and a signal indicating the value of the voltage a tier the division is input to the control terminal 121 of the shunt regulator 12.

At least one ola plurality of voltage divider resistive elements included in the voltage divider circuit 6 is a variable resistive element 61 with a variable resistance value, so that the size of the constant current flowing through the LED 22 can be changed by changing the resistance value of the variable resistive element 61. [0048.1 With the particle analysis device 20 configured in this way, the feedback circuit formed by the shunt regulator 12 operated by a single power supply is used as the constant current circuit I. so that the configuration can be made less expensive than that of an operational amplifier, the entire device can he kept compact. and while the LED 22 is turned on and off repeatedly in a short period of ime, a constant current can be applied to the LED 22 during the on time.

[00491 Also, since thecathode * ing element 2 is at ound potennal the voltage requned to drive the ss itching1 11 n is II.

[0050J Besides, since the switching element 2 is connected in series the the switching element 2 can switch the LED on and off faster than when it is connected in parallel with the LED 22.

[0051.) In addition, since the first resistive element 4, which has a resistance \faith, smaller than that of the LED 22 when a constant current is flowing through the LED 22. is connected in parallel with the LED 22, immediately after the LED 22 is turned to the off state front the on state, the current does not flow to the LEE) 22 but to the first resistive element 1. thus enabling the prevention of afterglow generation.

In addition, since at least one of the voltage divider resistive elements included in the voltage divider circuit 6 provided between the measurement element I I and the shunt regulator 12 is the variable resistive element 61 with a variable resistance value, the size of the constant current flowing, through the LED 22 can be adjusted by changing the resistance value of the variable resistive element 61.

[00531 Here, as an aspect to change the site of the constant current flowing through the LED 22. it is possible to use a variable resistor ibr the measurement element 11. but w hen a current of several amperes flows through the LED 22, for example. a variable resistor that can withstand such a large current will be expensive and large, causing the device to he expensive and large, lithe voltage divider resistive element 6i included in the voltage divider circuit 6 is a variable resistive element, as in the present embodiment, the current flowing through the voltage divider resistive element 61 can be reduced even if a large current Bows through the LED 22, and an inexpensive and compact variable resistive element can be used, allow big the device to be low-cost and compact, Furthermore, since the particle analysis device 20 can be kept compact as described above, the particle analysis device 20 can he attached to and detached from the cell housing space formed in the enclosure 40 of the device body 101 Gtliout difficulty, even i -11 housing space is a narrow space.

Besides, the poet ly V of the device body 101 is also used a er supply V to supply power to the LED 21 which allows the particle analsis unit 100 to be mote compact.

10056 I the present invention is not hmited to the above-described embodiments.

For example. the particle analysis device 20 is attached to and detached from the device body 101 in the above embodiment tit it may be used as a stand-alone device in The particle size distribution measurement device 30 of the above embodiment measures particle size distribution based on a static light scattering theory. but it may alternatively measure particle size distribution based on a dynamic scattering theory, that is, particle size distribution may he calculated based On fluctuations in kik intensity detected by a light detector.

10059I Fm.trt hermore. ahltOthlh one second resistive clement 5 is used in the above emhod a plurality of second resistive elements 5 connected in parallel and/or series may, be used, as illtistrateci in FIG. 4.

With such a configuration, the amount of went flowing through mel element 5 can be reduced. and the amount of heat generated by the resistive can be reduced.

[0060] Besides, for the particle analysis device 20. a constant current diode (constant current element) that keeps the current at a constant level tnay be used illStend of the second resistive element 5.

With such a configuration, as the voltage measured by the measurement element I I increases. the current flowing from the catItode to the anode of the shum regulator 12 increases, and the current flowing from the second resistive element 5 to the cmirent control element 13 decreases by that amount, and the current flossing through the LED 22 decitiases.

On the other hand, as the voltage measured by the ineasurement element I decreases, the COITC111 flowing from the cathode to the anode of the shunt regulator 12 decreases, and the current flossing from the second resistive element 5 to the current control element 13 increases by that amount, and the current flow ing through the LED 22 increases.

In addition, although one transistor is used as the current control element 13 in the above embodiment, a so-called Darlington transistor with a plurality of transistors connected in the Darlington configuration rnay be used as a current demerit. as illustrated in FIG. 5.

With such a conlinuranon. the current m tactor can he vwed. 0062]

In addition, in the above embodiniet a voltage divide' circuit is pi-ovicled between the shunt regulator 12 and the measurement element I I. However. this voltage divider circuit is not necessarily needed, and the voltage (current) measured by the measurement element II may be directly input to the control terminal 121 of the shunt regulator I 2, [00631 In the above embodiment, the sss itching element:2 is connected in series with the LED 22, but it may be connected in parallel ssith the LED 22. [00011 In add it ion, in the above embodiment. par dispersed in a dispersion medium are used as an analysis or measurement target, but for example, pmsder inay be analyzed or measured without being dispersed in a dispersion mednim. [0065.1 her variations and combinations of various embodiments ma) be made as long re not against the purpose of the present invention.

Industrial Applicability I 0066

According 10 the present uVcIl000, II is possible to repeat the turning on and off olan LED in a short period of time and toapp!) a constant current to the LED during the on lime. While keeping the entire device compact and \\ nil an inexpensive configuration. I 8

Claims

CLAIMSA particle analysis device that analyzes a characteristic of particles from an image obtained by imaging the particles, the particle analysis device comprising: an LED that emits light to the particles: a constant current circuit that tlovs a constant current to the I ED: and a switching element that is connected to die constant current circuit and turns on and off the current flowing through the LED, wherein the constant current circuit includes a measurement element that is connected in series with the Ero, meastres the current flowing through the LED, and outputs a measurement signal.a shunt regulator that outputs a feedback signal based on the measurement signal, and a elliTent control element that controls the current flowing through the LED h the feedback signal.
2.The particle analsis device according, to claim I. wherein the shunt regulator includes a control terminal that is connected to an anode side of the measurement element and receives an input of the measurement signal, and an output terminal that outputs the feedback signal and is connected to a control terminal or the current control element, and a resistive element having a predetermined resistance value is connected between the output tenninal of the shunt regulator and the control terminal of the current control element.
3. "Hie particle analysis device according toelaim I or2. wherein a cathode side of the switching element is at ground potential.
The particle analysis device according to any one ol'claims I to 3, wherein tlt switching element is connected in series with the LED.
The particle analysis device according to any one of claims I to 4. nrther comprising a resistive element dial is connected in parallel with the LED and has a resistance value smaller than a resistance value or the LED \ hen the constant current is H owing 1bn:tug].) the I Tr), 6.
The particle analysis device according 'claims I to 5, vherein a voltage divider circuit is provided betweert the measurement element and the shunt regulator. and at least one of voltage divider Itsistiveelements include( in the voltage dividet circuit is a variable resistive clement with a variable resistance value.
The particle analysis device according to any one of claims I to urthel comprising an imaging device that images the particles, \\ herein a cell housing the particles. the TED, the constant current circuit, and the imaging device are unitized and configured to be attachable to and detachable from a device body.
8. A particle analysis unit comprisii he particle analysis ( evice and the nevice both according to claim 7, g herein the device body includes a particle size distribution measuremeni device and an enclosure housing the panicle size distribution measurement device, and the particle analysis device is housed in the enclosure together 'N'ith the particle size distribution measurement device.
9. Hie particle analysis unit according to claim 8. "herein a poser supply of the device body is also used as a power supply to pog Cr the LED.