SU798553A1

SU798553A1 - Photoelectric dispersed-material particle counter

Info

Publication number: SU798553A1
Application number: SU782686301A
Authority: SU
Inventors: Сергей Васильевич Захарченко; Сергей Михайлович Коломиец; Владимир Владимирович Смирнов; Геннадий Федорович Яскевич
Original assignee: Институт Экспериментальной Метеоро-Логии
Priority date: 1978-11-09
Filing date: 1978-11-09
Publication date: 1981-01-23

Description

(54) ФОТОЭЛЕКТРИЧЕСКИЙ РЕГИСТРАТОР ДИСПЕРСНЫХ(54) PHOTO-ELECTRIC RECORDER DISPERSARY

ЧАСТИЦPARTICLES

Изобретение относитс к технике измерени частиц, взвешенных в газах или жидкост х, и может быть использовано в химической технологии, геофизике при контроле загр знени окружающей среды. Известны фотоэлектрические регистраторы частиц, содержащие формирующий световой пучок дл освещени исследуемых частиц,, схему прососа частиц через освещенную область (рабочий объем и приемную систему, состо щую из фотоприемника и анализатора амплитуды импуль сов 1. Недостатками известных фотоэлектри ческих регистраторов вл ютс искажение функции распределени частиц по размерам и их истинной концентрации за счет одновременного попадани в ра бочий (чувствительный) объем регистратора двух или более частиц, регистрируемых прибором как одна крупна Эта погрешность существенно возрастает при увеличении концентрации, поэтому указанные приборы используютс лишь при сравнительно невысоких концентраци х частиц. Кроме того, известные устройства оказываютс чувствительными к различного рода помехам, поскольку с выхода фотоприемника на анализатор поступает случайна последовательность импульсов , переменных по амплитуде и длительности , среди которых могут оказатьс и импульсы помех, принимаемые прибором за частицы, если их амплитуда превышает порог срабатывани амплитудного анализатора. Наиболее близким к предлагаемому по технической сущности вл етс фотоэлектрический регистратор дисперсных частиц, включающий осветитель с диафрагмой, узел прососа частиц, фотоприемник , подключенный к счетному входу анализатора амплитуд импульсов и измеритель длительности импульсов, соединенный со схемой запрета, выход которой подключен ко входу анализатора амплитуды импульсов 2. Недостатком известного устройства вл етс то, что селекци по длительности оказываетс недостаточно эффективной , поскольку требует посто нства скорости npocfeca частиц через рабочий объем, обеспечить которую достаточно трудно. Более того, при малых концентраци х иногда бывает необходимо преднамеренное увеличение скорости прососа с целью получени за врем экспозиции представительных проб аэрозол The invention relates to a technique for measuring particles suspended in gases or liquids, and can be used in chemical technology, geophysics, and in monitoring pollution of the environment. Photovoltaic particle recorders are known that contain a forming light beam for illuminating the particles under study, a circuit for pumping particles through the illuminated area (the working volume and the receiving system consisting of a photodetector and a pulse amplitude analyzer 1. The drawbacks of the known photoelectric recorders are distortion of the particle distribution function in size and their true concentration due to the simultaneous fall into the working (sensitive) volume of the recorder of two or more particles recorded by This error increases significantly with increasing concentration, therefore, these devices are used only at relatively low particle concentrations.In addition, the known devices are sensitive to various kinds of interference, since a random sequence of pulses of varying amplitudes comes from the photodetector output and durations, among which may also be interference impulses, taken by the device as particles, if their amplitude exceeds the threshold or amplitude analyzer. The closest to the proposed technical entity is a photoelectric recorder of dispersed particles, including an illuminator with a diaphragm, a particle projection assembly, a photodetector connected to the counting input of the pulse amplitude analyzer and a pulse duration meter connected to the inhibitor circuit, the output of which is connected to the input of the pulse amplitude analyzer 2. A disadvantage of the known device is that the selection in duration is not sufficiently effective because it requires constant speed. STI npocfeca particles through the working volume, which is rather difficult to provide. Moreover, at low concentrations, it is sometimes necessary to deliberately increase the rate of pumping in order to obtain representative aerosol samples during the exposure time.

И наоборот - при больших концентраци х во избежание перегрузки анализатора иногда необходимо уменьшение скорости прососа. Изменение скорости прососа ведет к изменению длительности импульса от частицы и к необходимости йосто нной регулировки измерительной схемы. Кроме того, упом нутое устройство остаетс чувствительным к помехам , длительность которых меньше или равна времени пролета частицы через рабочий объем. Относительно высоким остаетс и нижний предел размеров регистрируемых частиц.And vice versa - at high concentrations, in order to avoid analyzer overload it is sometimes necessary to decrease the pumping speed. A change in the speed of the pumping leads to a change in the pulse duration from the particle and to the need for a constant adjustment of the measuring circuit. In addition, said device remains sensitive to interference, the duration of which is less than or equal to the time of flight of the particle through the working volume. The lower limit of the size of the recorded particles also remains relatively high.

Цель изобретени - повышение помехоустойчивости , снижение нижнего предела размеров регистрируемых частиц, повышение эксплуатационных характеристик .The purpose of the invention is to increase noise immunity, reduce the lower limit of the size of the detected particles, increase operational performance.

Поставленна цель достигаетс тем что в фотоэлектрическом регистраторе частиц диафрагма выполнена в виде пр моугольника, две стороны которого параллельны направлению движени частиц , и снабжена непрозрачной полосой, расположенной под углом к направлению движени частиц, не равным нулю причем размер полосы в направлении движени частиц выбран меньше размера стороны пр моугольника, параллельной направлению движени частиц; в фотоэлектрический регистратор частиц введены: коммутатор, схема управлени коммутатором, три измерител длительности импульсов и решающее устройство , выдающее сигнал запрета .анализа в случае выполнени услови The goal is achieved by the fact that in the photoelectric particle recorder the diaphragm is made in the form of a rectangle, the two sides of which are parallel to the direction of movement of the particles, and equipped with an opaque strip at an angle to the direction of movement of the particles which is not equal to zero, the sides of the rectangle parallel to the direction of movement of the particles; A switch, a switch control circuit, three pulse duration meters and a resolver are inserted in the photoelectric particle recorder, which produce a signal to ban the analysis if the condition is met

ti-tTi а-Ъti-tTi a-b

где Ti , г длительности импульсов , соответственно, с первого, второго и третьего измерителей длительности импульсов; а - размер диафрагмы в направлании движени частиц; Ь. - размер непрозрачной полосыwhere Ti, g pulse duration, respectively, with the first, second and third pulse width meters; a is the size of the diaphragm in the direction of movement of the particles; B. - size of opaque strip

в том же направлении, причем управл ющий вход коммутатора подключен к выходу схемы управлени коммутатором, второй вход коммутатора и вход схемы управлени коммутатором подключены к фотоприемнику, йба выхода коммутатора подключены ко выходам первого и третьего измерителей длительности импульсов, выход фотоприемника подключен ко входу второго измерител длительности, три входа решающего устройства подключены к выходам из лерителей длительности импульсов , а вход запрета анализатора амплитуды подключен к выходу решающего устройства.in the same direction, with the control input of the switch connected to the output of the switch control circuit, the second input of the switch and the input of the switch control circuit are connected to the photodetector, and the output of the switch are connected to the outputs of the first and third pulse width meters, the output of the photodetector is connected to the input of the second duration meter , three inputs of the resolver are connected to the outputs of the pulse duration pulse, and the inhibit input of the analyzer of the amplitude is connected to the output of the resolver va.

, Кроме того, в фотоэлектрический регистратор дисперсных частиц введены схемы вычитани , схема делени , причем оба входа схемы вычитани подключены к выходам первого и третьего измерителей длительности импульсов, выход схемы вычитани подключен к одному входу схемы делени , ко второму входу этой схемы подключен выход второго измерител длительности, а выход схемы делени подключен к счетному входу анализатора длительности, а вход запрета анализа анализатора длительности подключен к выходу решающего устройства.In addition, a subtraction circuit, a dividing circuit were introduced into the photoelectric recorder of dispersed particles, both inputs of the subtraction circuit are connected to the outputs of the first and third pulse duration meters, the output of the subtraction circuit is connected to one input of the division circuit, and the output of the second meter is connected to the second input of this circuit the duration, and the output of the dividing circuit is connected to the counting input of the duration analyzer, and the prohibition input of the analysis of the duration analyzer is connected to the output of the resolver.

На чертеже изображена блок-схема фотоэлектрического регистратора дисперсных частиц.The drawing shows a block diagram of a photoelectric recorder of dispersed particles.

Регистратор состоит из осветител 1, формирующей оптики 2, 3 и 4 и пр моугольной диафрагмы с непрозрачной наклонной полосой 5, формирующих рабочий (чувствительный) объем б регистратора , через который просасываютс измер емые дисперсные частицы, фотоприемника 7, выход которого соединен с входами усилител -формировател 8 и амплитудного анализатора 9. Выход усилител 8 соединен со входом устройства 10 управлени коммутатором , входом коммутатора 11 и входом измерител 12 интервалов времени движени через непрозрачную полосу (длительность ч}. Выход устройства 10 управлени коммутатором подключен к управл ющему входу коммутатора 11, который своими выходами подключен ко входам измерителей 13 и 14 длительности импульсов (длительности Т и Tj ) . Выходы измерителей длительности 12, 13, 14 подключены к трем входам решающего устройства 15, с выхода которого снимаетс сигнал запрета анализа , поступающий на входы запрета анализа анализатора 9 амплитуды и анализатора 16 координаты. Выходы измерителей 13 и 14 длительности импульсов подсоединены к входам вычитающего устройства 17, выход которого соединен с первым входом схемы 18 делени , второй вход схемы 18 делений соединен с выходом измерител 12 длительности интервала а . Выход схемы делени соединен со входом анализатора 16 координаты , ВЕлход которого соединен с одним из входов перемножающего устройства 19, к другому входу этого устройства подключен выход анализатора 9 амплитуды. Дополнительный выход измерител 12 длительности паузы coeдIfнeн со входом устройства 20 формировани сигналов сброса/Электроды 21 подключены к источнику 22 напр жени .The recorder consists of an illuminator 1, forming optics 2, 3 and 4 and a rectangular diaphragm with an opaque inclined strip 5, forming a working (sensitive) volume b of the recorder through which the measured dispersed particles are sucked, a photodetector 7, the output of which is connected to the amplifier inputs - the driver 8 and the amplitude analyzer 9. The output of the amplifier 8 is connected to the input of the switch control device 10, the input of the switch 11, and the input of the meter 12, the time intervals of movement through an opaque strip (h duration). The output of the switch control device 10 is connected to the control input of switch 11, which is connected to the inputs of pulse duration meters 13 and 14 (duration T and Tj) with its outputs. The outputs of duration meters 12, 13, 14 are connected to three inputs of the solver 15, from the output which removes the analysis inhibit signal, which comes to the analysis inhibit inputs of the amplitude analyzer 9 and the coordinate analyzer 16. The outputs of the pulse width meters 13 and 14 are connected to the inputs of the subtractor 17, the output of which one with a first input of dividing circuit 18, the second input circuit 18 connected to the output division 12 meter interval and duration. The output of the division circuit is connected to the input of the analyzer 16 coordinates, the Velhod of which is connected to one of the inputs of the multiplying device 19, and the output of the analyzer 9 of amplitude is connected to another input of this device. The additional output of the meter 12, the duration of the pause, is combined with the input of the device 20 for generating the reset signals / Electrodes 21 are connected to the voltage source 22.

Устройство работает следующим образом .The device works as follows.

Claims

Using a source of light 1 and a lens 2 into the working volume 6 of the device, a rectangular aperture 5 with an opaque strip is designed. When aspirating a single particle through the working volume illuminated in this way, two pulses of scattered light are generated, with duration and tj, separated by a time interval tij equal to the time of flight of the particle through an opaque strip. These pulses are converted into electrical signals by a photodetector 7 equipped with a light-collecting optics 4. The signal from the photodetector 7, 5 strong, formed by the amplitude h in the amplifier forming the 8, is delivered to the switch control device 10, which through the switch 11 alternately connects the output of the amplifier B to the input of the meter 13 and 14 of the duration of the pulse. The meter 12 intervals T measures the duration of the time intervals between pulses of scattered light JT, and yi. The signals from the outputs of the three meters 12-14 duration go to the three inputs of the decisive device 15, the output of which, if the condition is satisfied, is . , a signal appears for the prohibition of ha t. coming in at the inputs of the analysis ban of analyzers 9 and 16, where a is the geometric height of the working volume; B is the length of the opaque strip in the direction of the squander of particles. The signals from the outputs of the meters 13, 14 duration go to the inputs of the subtractor 17 and from the output of the meter 12 duration to the input of the dividing circuit. Nodes 17 and 18 calculate the function -C, which in the analyzer 16 coordinates the passage of the particle through the working volume the value of which depends on the size of the particle of its charge and voltage applied to the electrodes 21. From the output of the analyzer 16, the signal arrives at the input of the multiplying device 19, to the second input of which the signal comes from the analyzer 9 of amplitude. When a particle passes through volume b, each particle produces two pulses with an interval between them equal to the time the particle passes through an unlighted region I, and the ratio between the pulses is determined by the expression. where t, tj, are the durations of the pulses corresponding to the passage of the particle through the illuminated zones of the working volume; a is the size of the diaphragm in the direction of movement of the particles; b - the size of an opaque polbs-in the same direction, does not depend either on the speed of procuring or on the placement of particles. Therefore, the introduction of a decision analyzer into the analyzer, which generates an analysis prohibition command in the event that the condition tj + vi is satisfied, ОЬ t Ъ, eliminates the possibility of registering a false signal (noise or noise signal). This makes it possible to detect particles that are only slightly higher than the noise level, and also to exclude from the analysis interferences of almost any nature and duration, and to reduce the requirements on the accuracy of maintaining the speed of particles throughput. In addition, in the proposed device, it is possible to determine the coordinates of the particle's span in the working volume, information about which is contained in the difference in the durations of the pulses formed when the particle passes through two illuminated areas of the working volume. For this purpose, a subtraction circuit, a dividing circuit, a difference pulse width analyzer, and an information output circuit are introduced into the recorder. In this case, two inputs of the subtraction circuit are connected to the codes of the first and third pulse duration meters. The output of the subtraction circuit is connected to one of the INPUT 9 division circuit, to the second input of which the output of the pulse width meter TD is connected. The output of the dividing circuit is connected to one of the inputs of the pulse width analyzer, to the second input of which the output of the resolver (prohibition circuit) is connected. In addition to measuring the size and concentration of particles, it is also possible to determine their electric charge in a photoelectric recorder if an electric field is created before particles enter the Illuminated Zone, under which a charged law is distributed in space according to a certain law depending on their mobility, t . size, size, and charge mark. In particular, depending on the sign of the charge, the dispersed particles are displaced relative to the injection plane to the left and to the right. The magnitude of the displacement is proportional to the mobility of the particle. Uncharged particles move along the center of the channel. Quantitatively, the relationship between the electric charge of a particle g and its coordinate X at the output of a flat capacitor 21, of length n, which creates a field of strength E, can be expressed by the relation. (J: x) .nV where V - flow rate g - particle size; f is the dynamic viscosity of the air; X is horizontally measured from the particle injection plane. The sign of the x coordinate is determined by the sign of the particle charge, and the absolute magnitude of the displacement x is the charge of the particles. The relationship between the x-coordinate of the particle's passage through the illuminated working volume and the device-measured pulse duration t, Tg, t can be found from the following relation Stgot (C where b is the vertical opacity of the opaque strip; 0 is its angle of inclination to the axis aspiration of the aerosol. Charging information can be obtained by installing apertures of a simpler configuration, for example, in the form of a single triangle. In this case, the device is simplified because only one duration is measured, but the requirement for stability of the velocity is increased. wasp (the parameter V enters into the calculation formula for charging not in the first step as in (1), but in the second). Thus, installation of the diaphragm and blocks into the recorder allows to significantly increase the noise immunity of the device and reduce the lower limit of the measured particles This is achieved by teM; that only impulses arising during the passage of a particle through the working volume and having temporal relations satisfying the condition are passed on to the analysis. a-3g, b The probability of the appearance of noise or interference signals satisfying this condition is small. The use of the invention improves the performance of the instrument. Claim 1. A photoelectric recorder of dispersed particles, including an illuminator with a diaphragm, a particle prosper node, a photodetector connected to the net input of the pulse amplitude analyzer and an impulse duration meter, the output of the photoreceiver being connected simultaneously to one of the prohibition circuit inputs and the pulse duration meter input The output of which is connected to the second input of the inhibiting circuit, the output of which is connected to the input of the analyzer of the amplitude of pulses, which is resistance and lowering the lower limit of the size of the measured particles, as well as improving operational characteristics, the diaphragm is made in the form of a rectangle, the two sides of which are parallel to the direction of movement of the particles and provided with an opaque strip at an angle to the direction of movement of the particles that are not equal to zero, and the size of the strip in the direction of particle motion is chosen smaller than the size of the side of the rectangle, parallel to the direction of particle motion. 2. The registrar according to claim 1, characterized in that a switch, a switch control circuit, three pulse width meters and a resolver are inputted into it that outputs an analysis inhibit signal in the case where i, 2 is met, ъ pulse width, respectively , from the first, second and third pulse duration meters; a is the size of the diaphragm in the direction of movement of the particles; b is the size of the opaque pdlos in the same direction, the switch control input is connected to the output of the switch control circuit, the second switch input and the switch control circuit input are connected to the photodetector, both switch outputs are connected to the first and third pulse width meter inputs, the photodetector output is connected to the input of the second duration meter, three inputs of the resolver are connected to the outputs of the pulse width meters, and the prohibition input of the amplitude analyzer is connected to exit solver. 3. The registrar according to claim 1, characterized in that it introduces a subtraction circuit, a division circuit, both inputs of the subtraction circuit are connected to the outputs of the first and third pulse width meters, the output of the subtraction circuit is connected to one input of the division circuit, to the second input of this circuit. the circuit is connected to the output of the second duration meter, the output of the dividing circuit is connected to the counting input of the duration analyzer-, and the input of the analysis disablement of the duration analyzer is connected to the output of the resolver. Sources of information taken into account in the examination 1.Patent of France No. 2178352, cl. G 01 N 15/00, published 1975.

2.Schelchkov G.I. Automatic correction of the error of coincidence. Meteorologists and Hydrologists, 1978, 5, p. 100-186 (prototype).

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