DE9000252U1 - Device for determining the quantity of objects in a room - Google Patents

Description

DIPL-ING. HORST ROSE DIPPING.' PE-TER CAPSULE for DIPPING. PETER SOBISCH

' .!PATENT ATTORNEYS. ..· ''..''

ADMISSIONED BY THE EUROPEAN PATENT OFFICE - EUROPEAN PATENT ATTORNEYS

Patent Attorneys Rose, Kosel & Sobisch
PO Box 129. D-3353 Baa Oandersheim 1

Odastrasse 4a

PO Box 29

D-3353 Bad Gandersheim 1

Telephone (05382)4038 Telex 957 422 siedp d Fax (05382)4030 Telegram address: Siedpatent Badgandersheim

10 January 1980 YourFile No.:

Our file number _: 4 0 6 9 / 7

Fagus-GreCon Greten GmbH & Co. KG DESCRIPTION

Device for determining the quantity of objects in a room

The invention relates to a device with the preamble of claim 1.

Known devices of this type use radioactive, ultrasonic, mechanical, capacitive and light barrier measuring principles. In the case of radioactive measuring principles, the shielding of the radioactive Radiation causes difficulties and additional effort. The ultrasonic and capacitive measuring principles are highly dependent on the type of objects and on temporary changes in the properties of the objects, e.g. changing humidity. Ultrasonic, mechanical and light barrier measuring principles, the flowing objects can falsely trigger the detection of a level in the chamber. With the light barrier module principle, the

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Ol The need for precise alignment of the light barrier is a disadvantage. The mechanical measuring principle requires a relatively high level of maintenance. Furthermore, structural changes must be made to the room.

The mechanical measuring principle is also difficult to achieve with the necessary detection reliability when dealing with fine and/or light objects.

The invention is based on the object of improving the determination of the fill level of the objects in the room.

This task is solved by the features of claim 1. Objects of all types and sizes can be considered as objects that normally flow through the room. In particular, they can be particles such as dust or objects of larger dimensions such as grain, sawdust or wood chips. In all cases, it is possible to determine an undesirable fill level in the room quickly, safely and with little effort. Such a fill level can occur, for example, through caking, build-ups or bridging of objects in the room. The fill level leads, for example, to the subsequent undesirable filling of a container or pipe section enclosing the room. This is prevented according to the invention by the quick and reliable determination of the fill level. A silicon photodiode in PIN planar technology can be used as a photoreceiver, for example. The device according to the invention is able to reliably distinguish the undesired level from all other conditions in the room. To do this, three different light components emanating from the light transmitter are recorded by the photo receiver. On the one hand, this involves directly

^f '' of &ggr;&Igr;&iacgr;&igr;&pgr; I. I l 3(Mi(Jr) &ggr;&pgr;&igr;&igr;f'gnnommonns light., wurm &zgr; . FJ . no ridnr only w &eegr;&eegr; irj r>Gngonr; tänrln diin.h Hc &igr; Hnu ^r n ström* n. Lin wf)it(.'''ir L Lchtnn Ln il. i ". t durj enLgo , which comes from the Wn &eegr; d of the room and /or from 'lurch dnn F) &pgr; around r, t, römm de-&eegr; Gngen 3t ü n-

(J'' uan is reflected in the photo receiver. The third part of light is that which passes through translucent objects to the photo receiver. All light that is recorded is evaluated in the evaluation circuit connected to the photo receiver and is then converted into a horn signal. uprnl irhon. 5} &iacgr;&eegr; Ii t: Hin __... ..» _.. __.... .... &mdash; _ . &mdash; ^ _.._ ._ __.... ___

If the amount of light remaining through the photo receiver falls below that threshold value, the evaluation system signals the level of the objects in the room, e.g. by means of an alarm, to the operating personnel. The operating personnel can then immediately remove the undesirable level of the objects in the room and restore the desired flow conditions of the objects in the room. Areas of application for the device according to the invention include, for example, containers and pipes of dust extraction and drying systems. It is particularly advantageous that the device according to the invention is largely independent of the type of

no extensive adjustment measures of the light transmitter and photo receiver are required.

The design according to claim 2 requires only little effort, is easy to assemble and can be used, for example, up to a temperature of 70° C.

At higher temperatures, the optical fibers, which are temperature-resistant up to 350° C, allow the light transmitter and the photo receiver to be arranged at a sufficient distance from the wall of the room.

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" ■· &Pgr;&ogr; mn &eegr; claim &Lgr ; the luminous intensity of the radiation from the luminaires can be divided in a manner known per se by a current limiting factor f3i.n1. The pulsing of the light can be achieved, for example, by means of an IC y c-pulsed?

Control of a transistor in the power supply of the LEDs. The frequency and the duty cycle of the pulses at the output of the IC can be adjustable . By pulsing the light , disturbing DC in the room is rendered ineffective. The frequency can be 100 pulses/s and the duty cycle Γ&ig;%, for example.

According to claim 5, it is possible to monitor the Li< transmitter for malfunctions, e.g. cable or circuit defects. Normally, the monitoring voltage pulses of the same frequency as the LEDs and of a certain amplitude. If these pulses are missing at the input of the monitoring circuit or if they fall below an amplitude set as a threshold value, the (jberwa This prevents the device according to the invention from falsely concluding that there is a level in the room and giving a false alarm if the pulses are absent or if the pulses are of insufficient amplitude.

According to claim 6, the amount of light received by the photoreceiver can be evaluated in a particularly flexible and reliable manner. The threshold value can be set using the reference voltage and/or the amplification factor of the operational amplifier. This means that with only a small input, The construction and operational features of the wall and the room as well as the objects flowing in the room must be taken into account when designing the installation.

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01. The capacitive coupling according to claim 7 makes it possible to make any DC light component in the measuring range ineffective.

The features of claim 8 provide an adjustable time delay between detection and reporting of the state that the photoreceiver has detected a light level below the threshold value. The time delay is intended to prevent a suspected fill level from being reported too quickly . Depending on the design and practical conditions, it may happen more or less frequently that fill levels disappear again of their own accord after a short period of time, or that only relatively large objects move relatively close to the photoreceiver, meaning that there is actually no fill level, but that normal conditions have returned after the large object has been removed from the measuring section. In these cases, the reporting of a fill level would be a false alarm.

The features of claim 9 make it possible to increase the detection sensitivity of the device.

Further features and advantages of the invention will become apparent from the following description of embodiments. It shows:

Fig. 1 a cross-section through the wall of a room without any objects flowing through it, with a device attached to the wall,

Fig. 2 is a representation according to Fig. 1 with objects arranged in the room,

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&bull;-B-.

(Jl. Fig. 'J a representation according to the previous &ugr; f c| ignngcnon figures with &agr; in on the translucent object,

Fig. 4 the sectional view along line IV-IV in ! ^: ig. ?,

Fig. 5 din sectional view according to Fig. 4, but with the new filling level of the objects,

Fig. 6 a circuit diagram of a light transmitter,

Fit}. 7 a light emitting diode with a light transmitter and photo receiver remote from the room,

Fig. 8 a block diagram for the photo receiver and its evaluation circuit and

Fig. 9 is a block diagram of an additional evaluation circuit.

In Fig. 1, a room 1 is delimited by a wall 2. A light transmitter 4 is inserted into an opening 3 in the wall 2 and leads into the room 1. Opposite the light transmitter 4 and aligned with it, a photo receiver 5 is arranged in an opening 6 in the wall 2 and leads into the room 1. An evaluation circuit 7 with an output line 8 is connected to the photo receiver 5.

^According to Fig. 1, there are objects in the room λ Xiina so that a light beam 9 from the light transmitter can reach the photo receiver 5 unhindered.

In all drawings, identical parts are provided with identical reference numbers.

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Ol Normally, however, room 1 is divided into
objects 10, which in the case of Fig. 2
are not translucent. The objects 10 can be, for example, wood chips or grain. In the illustration in Fig. 2, the light beam

9 from the light transmitter 4 to the photo receiver 5, because in
There happens to be no object 10 in its path.
On the other hand, the light transmitter 4 is not a point-shaped light source, but a light source that is emitted at a considerable solid angle
practically diffusely. This means that a beam of light 11
reflected from the wall 2 and reaches the photo receiver 5 in this detour. Other light rays 12 are reflected from passing objects 10 and

only then reach the photo receiver 5.

Another possibility is illustrated in Fig. 3. There is a translucent gauge 10, e.g. a
Wood chip, in the path of the light beam 9. The light beam 9 penetrates the translucent object 10 and reaches the photoreceptor 5 with reduced intensity.

In Fig. 4, a flow direction 13 of the objects

10 indicated by the room 1. The wall 2 represents, for example,
the lower outlet area of a cyclone separator.

In Fig. 4, the amount of flowing objects 10 in the room is still so small that enough light from the
If the light sensor 4 hits the photo receiver 5 in the different ways described in Fig. 1 to 3, no fault message is output by the evaluation circuit 7.

The operating state according to Fig. 5 is different, where, in

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&bull; · &mdash;«&Ogr;&mdash; · · &igr; · »

In this case, due to bridging of the objects 10, an undesirable blockage or a level of filling has occurred in the room 1. Now either no light at all or only too little light can reach the photo receiver 5 from the light transmitter 4. The result is that, in a manner to be described later, the evaluation circuit 7 recognizes this state and issues an alarm. The operating personnel are thus made aware of the blockage and can provide assistance.

Fig. 6 shows details of the light transmitter 4 and its circuit arrangement. The supply voltage is fed via a line 14 to an IC 15 on the one hand and to a transistor 16 on the other. The IC 15 sends control pulses 18 of, for example, 100 Hz to the transistor 16 via an output line 17. The frequency of the control pulses 18 can be changed by a capacitor 19, while the duty cycle of the control pulses 18 can be set via the ratio of resistors 20 and 21 on the IC 15.

The output of the transistor 16 is connected to four LEDs 22 to 25 connected in series and switches them on and off according to the frequency and the duty cycle of the control pulses 18. The light emitted by the LEDs 22 to 25 enters the room 1 through an inlet window 26 in the opening 3. Fewer or more than four LEDs could also be used.

Connected to the cathode of the light-emitting diode 25 is a current limiting circuit 27, which is known per se. Between the aforementioned cathode and the current limiting circuit 27, a monitoring circuit 29 of a known type is connected via a line 28.

The line 28 carries pulses 30, the frequency and duty cycle of which correspond to the light pulses of the light emitting diodes 22 to 25. The amplitude of the pulses 30 is normally above a threshold value that can be set in the monitoring circuit 29. Only when the amplitude drops below that threshold value, e.g. due to line or other malfunctions in the light transmitter 4, is this detected by the monitoring circuit 29 and an alarm is given so that this malfunction within the light detector 4 does not lead to a false conclusion about a fill level in the room 12.

According to Fig. 7, high temperatures prevail in the room 1 and on the wall 2, for example over 70°C, which could impair the function of the light transmitter 4 and the photo receiver 5 and its evaluation circuit 7. The light transmitter 4 and the photo receiver 5 with its evaluation circuit 7 are therefore arranged at a distance from the wall 7 according to Fig. 7. These distances are each bridged by an optical waveguide 31 and 32, e.g. optical fiber cable.

According to Fig. 7, only one light-emitting diode 33 has been used in the light transmitter 4. The light-emitting diode 33 is adapted to a receiving piece 34 of the optical waveguide 31.

An output piece 35 opens into the opening 3 of the wall 2 and radiates the light into the room 1. A receiving piece 36 of the optical waveguide 32 receives light from the room while an output piece 37 of the optical waveguide 32 transmits this light in a good mechanical adaptation to the photo receiver 5.

According to Fig. 1, the photoreceiver 5 converts the L rchtorgio received by it into photocurrent pulses 30, which

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The frequency and duty cycle correspond to those of the control pulses 18 (Fig. 6). The photocurrent pulses 38 are converted into voltage pulses 40 in an operational amplifier 39. The gain ratio of the operational amplifier 39 can be adjusted by an adjustable resistor 41 connected in a feedback loop.

An output 42 of the operational amplifier 39 is connected via a capacitor 43 to a first input 44 of a comparator 45. A reference voltage U _f of selectable value is applied to a second input 46 of the comparator 45. A timing element 48 is connected to an output line 47 of the comparator 45 for better signal transmission.

According to Fig. 9, a retriggerable timer 49 is also connected to the output line 47, which, after the absence of pulses on the output line 47, only emits an output signal on its output line 50 after an adjustable time delay. Finally, if a signal occurs on the output line 15, a relay 52 is controlled via a transistor 51 and a switch 53 is closed. This can, for example, close a circuit of a warning lamp. The warning lamp shows the operator that an undesirable level of objects has occurred in the room (Fig. 5).

Claims (7)

EXPECTATIONS 1. Device for determining the quantity of objects (10) in a space (1) delimited by a wall (2) through which a stream of objects (10) flows in the normal state, characterized in that the light can be introduced into the room (1) by a light transmitter (4) of the device, that a photoreceiver (5) of the IG device is assigned to the light sensor (4) at a distance such that the photoreceiver (5) can receive light from the light transmitter (4) from the room (1) even through the stream of objects (10), and that the photoreceiver (5) is connected to an evaluation circuit (7), which then detects a disturbance reports when the amount of light received by the photoreceiver (5) falls below a certain -2- DIC /! = Cash : NC RC LS.'. l Bad Gandersheim (bank code 250 500 00). Account no. 22 118 970 - Postgiro account: Postgiroamt Hannover (bank code 250100 30), account no. 6b715-307 —if * fJ1· rinr Ausweis.·tesrh&pgr; 1 tiHiri (/) R i.nstellbaren Schwellenwnrt &ogr; in Ri]. 1st and (Fie). &Ggr;)) the Gog r:i &igr; s t;ä &eegr; do (10) in the Flaum (1) occurred. > r, t . 2. Device according to claim 1, characterized in that the light transmitter (4) and the photo receiver (5) each open into the room (1) through an opening (3;6) in the wall (2). 3. Device according to claim 1, characterized. that the light transmitter (4) and the photo receiver (5) $ jewei.i , outside and at a distance from the wall (2) &kgr; are arranged such that the respective optical waveguide (31; 32) is crossed by an optical waveguide (31; 32), and that each optical waveguide (31; 32) opens into the room (1) through an opening (3; 6) in the wall (2). 4. Device according to one of claims 1 to 3, characterized in that the light transmitter (4) has a transmitter circuit with at least one light-emitting diode (22 to 25; 33), and that the at least one light-emitting diode (22 to 25; 33) is activated by pulsed current. 9&Pgr; hDaiifcrhlaniinn iln-rr-h HHo SonHorsrhalhunn nnt.snrpr.hnnri *«W ww«w&mdash; wa~·· &mdash; w^w..-j ~. &mdash; &mdash;&mdash; - - &mdash;&mdash; w vv.- &mdash;&mdash; .. &mdash;&mdash; · · & -.&mdash;&mdash;j&mdash; _.. .. emits pulsed light. 5. Device according to claim 4, characterized in that a monitoring circuit (29) monitoring the intended function of the light transmitter (4) is connected to the cathode of the single light-emitting diode (33) or to the cathode of the last of several light-emitting diodes (22 to 25) connected in series. 6. Device according to one of claims 1 to 5, characterized in that the evaluation circuit (7) has a -3- Ol dom Kotnompf öm(jbt ( &Ggr;)) nachgo' ¹ lun Ojinrntiuniiver strong (3'J) as a current/voltage converter, that an output (42) of the 0 ρ π rat ρ r > π s π first δ rk ρ rs ('''J) i'' ¹ with ei π (3 m first L input (44) of a comparator.5 M !3) OS, and that a reference voltage (U ,-) of selectable value can be applied to a second input (4L>) of the comparator (45). 7. Device according to claim 6, characterized in that a capacitor (43) is connected between the operational amplifier (39) and the first input (44) of the comparator (45). 0. Device according to claim 6 or 7, characterized in that a retriggerable timing element (49) is connected between an output of the comparator (45) and an output (8) of the evaluation circuit (7). &iacgr; 9. Device according to one of claims 1 to 8, characterized &iacgr; characterized in that the wavelength of the Light transmitter (4) emitted light and the duration length of the maximum photosensitivity of the photoreceiver (5).