FI69371C - FOER REFRIGERATION FOR OBSERVATION AV DROPP- OCH / ELLERPARTIKELFORMIGT MATERIAL - Google Patents

Description

6 9 3 71 1 Method and apparatus for detecting droplet and / or particulate material For the purpose of observing drop-off and / or particulate material 5

The invention relates to a method for detecting the presence of objects, in particular droplet and / or particulate material, measuring their size or their distribution and / or quantity, which method uses a transmitter arrangement for transmitting electromagnetic radiation or ultrasound pulsed through a measuring range to receiving devices. or the measured radiation is detected and detected from the measurement object, and thus a measurement signal is generated, in which method the pulses from the transmitting devices are detected and calculated by the receiving devices.

The invention further relates to a device 20 for carrying out the method, comprising a body part in connection with which the transmitting devices and the receiving devices are arranged opposite each other, between which a measuring area is arranged, in or near which passing objects are detected and in which the transmitter has a pulse generator supplying a transmitter component such as a light emitting semiconductor component or an ultrasonic transmitter, and the receiving devices include a receiver component such as a phototransistor or an ultrasonic receiver and amplifier, and a comparator unit and a measurement result detection or processing unit.

30 It is already known e.g. the so-called. a "tipping bucket" is a rain gauge in which rain is collected in a funnel from which droplets are counted by a mechanical counter.

A variety of optical devices for detecting or quantifying precipitation or other droplet-like particles or larger bodies are also known in the art, in which the detection is based on optical devices or the use of ultrasound. In these known devices, the light source is, for example, transmitted from a light source by radiation which is received, for example, by a phototransistor. For these devices, reference is made, by way of example, to U.S. Patents 4,179,218, 4,225,245 and 4,333,724 and GB Patent 2,080,555. The present invention is most closely related to FR Patent 7,440,094 (Publication No. 2293718), of which a known optical rain gauge using lenses and masks to provide a substantially rectangular beam with radiation and a measuring range. In this known device, as in some other similar devices, the transmitted radiation has to be scattered over a relatively wide area, with the consequence of the disadvantage that the device has a relatively small dynamic range. In addition, the use of a lens system requires very precise alignment.

The prior art has also had the disadvantage of instability and creep in the power of the transmitted 15 measurement beam beams. A further disadvantage of these optical measuring devices is that the background radiation, e.g. lighting variations, cause the measurement inaccuracy. A related drawback is also that contamination of the transmitter and receiver lenses causes an error. There has also been room for improvement in the detection of small droplets or 20 particles.

It is an object of the present invention to provide a method and apparatus based on electromagnetic radiation or ultrasound for measuring objects, measuring size or size distribution and / or quantity, which does not exhibit the above-mentioned drawbacks and which provides a more accurate measurement result with relatively simple devices.

It is a further object of the invention to provide a device from which the measurement results are obtained as a digital signal, for example as a series of pulses, the number of pulses of which depends, for example, on the amount of precipitation or other measurand.

The object of the present invention is to provide such a measuring device in which the measurement result is obtained at a variable frequency so that the detection and / or further processing of the measurement results is simple and the measurement result can be detected e.g. by a simple pulse counter.

3 69371 1 It is a particular object of the invention to provide a measuring device which is automatically adjustable according to changing environmental conditions, e.g. lighting conditions or soiling of various parts.

It is a particular object of the invention to provide such a measuring device in which laser light can be used in certain special applications and its special properties can be utilized.

It is a further object of the present invention to provide such a measuring and / or detecting device suitable for use in a variety of applications, such as rainfall measurements, visibility measurements, various contamination measurements, liquid dispensers, various medical and biological measuring devices such as blood cell measurement samples. -15 you do like the equipment fitted to the conveyor belts.

It is a further object of the invention to provide a measuring device whose mechanical structure offers the possibility to apply the method and the device also in such objects, such as industrial processes, where the conditions for measurement are difficult due to, for example, temperature, inaccessible measuring object or other factors.

In order to achieve the above and later objects, the method of the invention is mainly characterized in that the reference level or levels are arranged to adjust according to changes in measurement conditions, and that the number of pulses below said reference level or levels in a given time is used as a signal.

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The device according to the invention, in turn, is mainly characterized in that the receiving devices of the device further comprise a unit for generating a reference level or reference levels which, on the basis of the received signal, forms an adjustable reference level or levels.

According to the invention, the transmitter and the receiver are aligned so that when the objects to be measured are the so-called in the active region, a response is obtained to the receiver depending on the dimensions and / or amount of the object. The transmitter 35 69371 1 can be directed either directly to the receiver or in such a way that the transmitted electromagnetic radiation or ultrasound is scattered from the measurement object by the receiver.

By knowing the transmission frequency and calculating from the received pulses those which intersect the reference level or levels, the device according to the invention can be calibrated with respect to a certain target material. Due to the dimensions of some objects or the properties of the material, the dependence can be calculated directly.

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By changing the reference level, the sensitivity of the measurement can be affected and, if necessary, errors caused by variations in environmental conditions can be eliminated.

By selecting several different, e.g. repeatedly and automatically, changeable reference levels, a multi-channel measuring system is provided, which can be used, for example, to measure the size distribution of particulate objects.

When using optical cables on the receiving and / or transmitting side in the device according to the invention, the mechanical structure of the device can be well adapted to a number of different and even difficult measuring objects.

The invention will now be described in detail with reference to some embodiments of the invention shown in the figures of the accompanying drawing, to which the invention is not limited.

Figure 1 is a block diagram of a method and apparatus of the invention suitable for measuring, for example, liquid droplets such as rain.

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Figure 2 illustrates the transmitted modulated radiation as well as the received radiation passing through the active measuring range in different situations.

Figure 3 shows an example of a mechanical structure-35 of the device according to Figure 1.

Figure 4 shows the transmitter part of the measuring device.

li 5 69371 1 Figure 5 shows a receiver of a measuring system.

Figure 6 shows another alternative mechanical implementation of the invention using an optical cable on the receiver side.

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Figure 7 shows an application of the invention, e.g. for visibility measurement, in which one transmitter is used and two receivers adapted to cooperate with it.

According to Fig. 1, the pulse generator 11 of the transmitter section 10 generates pulses at a frequency of e.g. 1 kHz, which are fed to a pulse amplifier 12 and further controls a transmitter component 13, which is e.g. a narrow-beam LED operating in the infrared range.

The transmitter component 13 is directed directly towards the receiver component 21 of the receiver part, which is e.g. a photodiode. The received pulses are amplified by an amplifier 22, and in particular to minimize background interference, the reference level is formed on the basis of the level of the received pulses by a special electronic circuit 23 generating the reference level.

The amplified pulses and the reference level are applied to a comparator 24, which outputs a pulse UQUt, e.g. whenever the amplified pulse exceeds the reference level U These pulses are counted by a counter 25.

The device schematically shown above operates essentially as follows. 25 If the active area A is free of the objects to be measured, each transmitted pulse is received by the receiver. The reference level U1 is set slightly below the peak value of the pulses, whereby the transmission frequency U is also given to the counter as the output signal U of the comparator 24. When there is, for example, a drop in the active area A between the transmitter 13 and the receiver 21, the number of transmitted pulses depending on the speed and dimensions of the drop 30 does not arrive at the receiver.

The diameter 6 of the radiation beam K is, for example, <5 s: 1-4 mm. The length of the measuring interval L is, for example, 1 ^ 2-50 cm.

In Figure 2, curve a) depicts the transmitted modulated signal. Curve b) depicts the received series of radiation pulses in the case when no raindrops or other detectable objects hit the radiation beam K between the measuring 35 6 9 3 71 1. Curve c) shows a situation in which a very small drop has hit the streak beam K, whereby two pulses have been attenuated. Go d) to show a situation in which a large drop has hit the measuring beam K, whereby several pulses have been attenuated.

Although the invention has been described above and below with reference mainly to rain gauges or other methods and devices suitable for detecting, measuring size, amount or size distribution of relatively small particles in which the measurement signal is directed directly from the transmitter to the receiver, it should be emphasized that the invention is -for many applications, e.g. for detecting the number, size or presence of rather large pieces. The invention also includes applications in which the transmitted radiation is scattered from the measuring range. In scatter-based applications, it is advantageous to set the reference level U 1 used in the invention to a suitable level in advance or to arrange the reference level, e.g. with an external sensor, to be adjusted according to changes in the measurement conditions.

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Laser applications are also within the scope of the invention.

When using ultrasound as a measuring signal in the devices according to the invention, the ultrasonic transmitters are, for example, ultrasonic crystals 25 known per se or ultrasonic transmitters based on magnetostraction, and the receivers are also ultrasonic crystals or other microphone devices.

Fig. 3 shows a mechanical embodiment of the device, in which a body part 30 is arranged on the base 34, which is U-shaped comprising 30 end parts 31 and 32 and a horizontal part 33 connecting them. The transmitter component 11 is placed on the inner side of the other end inside the cover 16. The receiver component 21 is located on the inside of the second end portion 32 inside the cover 26. The shields 16 and 26 have open openings facing each other so that the radiation beam K can pass through the measuring interval L. The device 35 includes electrical wires (not shown) which supply the electrical power required by the device and the measurement results to the measurement data processing devices.

7 69371 1 The transmitter component 13 is, for example, the infrared transmitter FPE104 (Fairchild), which is a narrow-beam infrared transmitter.

As the receiver component 21, e.g. phototransistor TIL81 is used, which 5 can be used either transistor or diode connected. In diode switching, the response is almost linear. At low radiated power values, the transistor connection is usually about 400 times more sensitive than the diode connection. However, this would require that the portion of the disturbing background could be eliminated. In practice, however, the background radiation is so strong that changes in the payload signal do not cause a sufficient change in collector current. Therefore, a diode-coupled phototransistor must be used in this connection.

The electronics of the transmitter part 10 can be seen in Fig. 4. The function of the electronics connected to the transmitter part 10 is to supply a pulse of about 10 s, e.g. about 1 s, e.g. every 1 ms f = 1 kHz to the infrared LED 13. This requires an oscillator 11, a counter 15 and a power supply driver 15a in Fig. OA. The stable CMOS oscillator 11 can be implemented e.g. by the connection of Fig. A using three inverters MM74CO04. By selecting 11 R1 = R2 = 12 k 20 and CB 68pF in the oscillator 11, the frequency is practically 50 kHz. Timing signals of different lengths are obtained by the counter 15 by converting the output of the oscillator 13 into a clock pulse. Counter 15 MC1A0A0B is a 12-bit binary CMOS counter that increments at the falling edge of the clock pulse. The counter controls the circuit SN75325 of the power supply section 15a, which was originally designed as a memory-25 tidriver. The peak current is about 200 mA.

The structure and operation example of the receiver 20 can be seen in Figure 5. Upon entering the receiver 20, the information to be measured in the form of missing or attenuated pulses must be measured by means of the invention. The receiver 20 should separate and calculate the different pulses from the other undisturbed pulses. The detection of the measurement results is handled, for example, by comparing each pulse detected by the receiver 20 with an integrated average of the pulses calculated over a sufficiently long period of time. 1

When a lower than normal pulse is detected, detection occurs. Instead, if the disturbance is continuous (eg covering or soiling), the reference level decreases and no expression occurs. Similarly, the rapidly changing intensity of background radiation does not cause expression.

The electronic structure of the receiver is shown in Figure 5.

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A comparable voltage level U is required for the detection of received pulses. When the height of the measured and amplified pulse remains below this level U ^ detection occurs. Here, too, account must be taken of changes in the height of the pulses caused by, for example, fog, deterioration of the power supply, dirt, etc. For these reasons, the reference level U must be variable with the situation.

To create the reference level, the circuit 23 shown in Fig. 5 is used, which maintains a voltage level about 10% lower than the 15 input pulses on average. The comparative voltages are applied to a comparator 25 (e.g., MM74C909 (CMOS)), the output of which is in the LO state when the input pulse is above the reference level U 1. When the drop-induced intensity drop at the receiver is greater than 10%, the input pulse of comparator 24 remains below the reference level and comparator 20 remains in the HIGH state.

The CD452BC in block 27 is a CMOS-transmissive monostable whose pulse length (time constant) can be determined by external components (resistor and capacitor). Selecting a resistance of 2560 k and a capacitor of 47 nF gives a circuit time constant of about 2 ms.

The electronics shown in Figures 4 and 5 are designed to consume low power using IC-30 circuits implemented primarily with CMOS technology. Few pulsations also aim for low power consumption. When using denser pulse, all the monitored objects, eg drops, even the smallest ones are made visible. The measurement information can also be easily obtained from the receiver as a frequency change by taking the output signal from the input of the monostable 27.

By limiting the area of the receiving optocomponent 21, the active area is reduced in diameter, thereby "seeing" smaller

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35 69371 1 drops. Another way is to use lenses, which, however, complicates the mechanical structure. The sensitivity of the receiver 20 can also be adjusted by varying the reference level U 1. The development of components offers an opportunity to improve the resolution of the device, making it possible to obtain 5 more detailed information, e.g. on rainfall.

Creating more reference levels provides direct information on the size distribution of the droplets and, if necessary, their velocity. At its simplest, the creation of the reference planes U 1 can be realized in the block 23 according to the reference plane 10 of Fig. 5 by adding only a buffer and changing the 10 k / 100 k resistance ratio in the block 23. This creates a multi-channel measuring device, which allows different levels of signals to be applied to different channels, which facilitates and speeds up data processing.

Figure 6 shows an example of an alternative mechanical implementation of the device according to the invention, in which an optical cable is utilized on the receiver side. This device comprises a body part 40 consisting of a vertical body 41 placed on a base 46. Protruding from the vertical body 41 is a horizontal body 43 having an end portion 42.

A measuring gap L is formed between the vertical body 41 and the end 42. The transmitting optocomponent 13 is placed at the upper end of the vertical body 41 inside a cover 16 having an open outer end. The beam K of the measuring radiation R is received at the open end 45 of the optical cable 44. The optical cable 44 passing inside the body parts 42, 43 is used to transmit the measurement signal to the receiver 25 20. The optical cable can also be applied on the transmitter 10 side.

The use of the optical cable 44 provides several advantages, which are listed below: 1 - small opening angle and small diameter, as a result of which the light beam or active area is narrowed and small particles are seen, - many can be placed in parallel to see the movement of the particle, 35 - using the optical cable the measurement accuracy can be increased, 10 69371 1 - several cables of different diameters can be used simultaneously, whereby the drops to be measured e.g. the information obtained from the size distribution becomes more accurate, 5 - the mechanical structure can be substantially simplified, - the optical cable can be routed to even difficult measuring objects.

Figure 7 shows a variation of the invention in which one transmitter 10 'and two receivers 20' and 20 "adapted to cooperate with it are used. The distance of the transmitter 10 'from the first receiver 20' is 1 and the distance of the second receiver 20" from the transmitter 10T, respectively is, for example, 11 x 1. Then: 4C -rt -vsxl.

15 I, I e, where 1 o 1 ^ intensity Iq to receiver 20 'from transmitter 10' intensity transmitted v visibility 1 <distance from transmitter 10 'to receiver 20' 20 s 3 attenuation factor Corresponding _ _ -vsxllxl I0 »I e 2 o oc lOxlxvs. ...

25 - = e »and visibility L2 v In (I ^ / 12) / lOxlxs

The quantity v observed as described above can be used directly for visibility measurement or drip rain detection, or a combination thereof.

It is possible to use a receiver with a larger surface area of 20 "and thus more sensitive than the receiver 20 ', but e.g. mechanical aging and fouling favor the use of identical receivers 35 20' and 20". In a combined rain and visibility meter, a higher transmission intensity can sometimes be used if the sensitivity of the 20 "receiver imposes limitations.

11 60371 1 The following is a list of some typical applications of the method and apparatus of the invention, without limiting the invention in any way: rain measurement, drip rain and visibility measurement, flue gas and soot particle measurement and other pollution measurements, 5 liquid dispensers, blood cell measurement with sample, laser and a particle counter.

Variations in the mechanical solution, mainly through different fiber optic combinations, also make it possible to measure different size distributions.

The following are some general aspects of applying the method and apparatus of the invention. By reducing the cross-sectional area of the active area (radiation beam K), smaller droplets 15 are visible. By changing the transmission frequency f, the sensitivity of the device can be adjusted. When, in addition to the missing pulses, the level of the received measurement signal is detected, the effects of various error factors, such as the effect of wind in rain measurements, can be eliminated. When using an optical cable on the receiver and / or transmission side, the mechanical structure of the device 20 can be varied within very wide limits and adapted to the specific needs of the case. Using optical cables, it is possible to reach, for example, very narrow or otherwise difficult measuring objects, which may occur, for example, in various industrial processes. One application of the invention in rain measurement is one in which the moving mechanics of a "tipping-bucket" type meter per se is replaced by the measuring equipment according to the invention.

In the following, the claims are set forth within the scope of the inventive idea defined by the various details of the invention, which may vary and differ from those described above by way of example only.

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Claims (10)

A method for observing the presence of bodies, particularly of droplet and / or particulate material, for measuring the size, distribution and / or amount, in which method a transmitter arrangement (10) is used, which arrangement transmits pulsed electrode magnetic radiation or ultrasound through a measurement area (L) of receiver devices (20), with which the radiation passed through the measurement area (L) and / or from the measurement object is observed and plotted, and a measurement signal is generated, receiver devices (20) observe and count the pulses arriving from the transmitting devices, which in conjunction with the measurement object attenuate the eigenvalues p1 of the amplitudes below a given intrinsic value p1 a reference level (U U) or intrinsic values p1 of reference levels, U c) whether the reference levels are arranged to be regulated on the basis of the changes in the measurement conditions for caused the changes in amplitude in the coming signal and that the amount of pulses below said reference level (U 1 Patent claim 2. A method according to claim 1, characterized in that the amplitude of the pulses, the amplitude of which is below the reference level (Uref) or the reference levels, is measured during a given time interval and thus an interconnection signal is generated, with which the reference level (U U.) Or the reference levels are controlled. 3. A method according to claim 1 or 2, characterized in that the method uses several between 30 different Large Reference Levels (Uref), between which different levels of falling pulses are led to different measurement channels and the different measurement signals thus obtained are used inter alia. .a. for measuring the size distribution of the amount of material and / or the droplets and / or particles to be measured. 35 Method according to any of claims 1-3, characterized in that the pulse frequency of the measurement signal is substantially constant and falls within the range f = 1 Hz - 50 MHz. Method according to claims 1 to 4, characterized in that pulsed laser light is used as straining (R) to be transmitted. Method according to claims 1 to 5, characterized in that the difference (f -f,) between the known transmitter frequency (f) and the received frequency (f . by means of a pulse counter or the like. Apparatus for carrying out a method according to any of claims 1-6, comprising a body part (31-34; 40-46), in connection with which the transmitting devices 15 (10) and the receiver devices (20) are arranged opposite to each other. , between which a measurement area (L) is arranged, within or in proximity to which area located or thereby passing bodies is observed, and in which the transmitter (10) is provided with a pulse generator (11), with which a transmitter component (13) is fed, such as a light emitting semiconductor component or an ultrasonic emitter (12), 20 and to which receiver devices (20) a receiver component (21), such as a photoconductor or ultrasonic receiver and an amplifier as well as a comparator unit (24) and a detector (or processor) the measurement result, characterized in that the receiver devices (20) of the device belong to a further generating unit (23) for the reference level (U ^) or the reference levels, which generation unit due to the received signal forms an adjustable reference level (U,.) or levels. ref 8. Device according to claim 7, characterized in that the transmitter component (13) and the receiver component (21) are arranged between themselves so that the transmitter component transmits a substantially cylindrical or conical narrow radiation cone (K) through the measurement area, which radiation beam (K). focused on the active area of the receiver component (21). 1 II Device according to claim 7 or 8, characterized in that on the receiver side and / or transmitter side of the device a light cable (44) is used for transmitting the received and / or transmitted