DE2310490A1 - LIGHT ELECTRIC SMOKE OR FIRE DETECTOR - Google Patents

Description

Karl A. ßrose

Dip .'.- fcg.

Ό-Β013 Mim: i: .. n-Pullach
tit.lWiLi. 7) 335 70.7931782

vln / au Munich-Pullach, February 27, 1973

LA DETECTION ELECTRONIQUE FRANCAISE PROTECBAT, 20, Rue de la Republique, 92170 Vanves, France

Photoelectric smoke or fire detector

The invention relates to smoke or fire detectors, and more particularly optical or photoelectric such detectors.

Up to now, two types of photoelectric smoke and fire detectors have been generally used.

The first type of detector is based on the principle that there is obscuration a light source measures through the smoke, while the second type of detector is based on the "Tyndall effect" and allows to measure the light reflected by the smoke particles when they come into the light beam that is from a Light source is emitted.

These known detectors have a disadvantage that

for

consists in that / the generation of the necessary for the acquisition Light bundle a light source must be used whose mode of operation on the one hand on the light emission of a hot Object or body (e.g. incandescent lamp), and on the other hand on the generation of light emission by a light

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bent in a gas (in the case of a neon lamp).

These light sources have a relatively limited lifespan, they are fragile and sensitive to impact (more fragile Thread or electrodes brought too close together) and have a very low useful power.

If, in addition, a photoelectric fire detector has such a light source, the supply is made by the latter an energy in the order of magnitude of watts is required and this results in a detector installation with a certain Number of detectors, resulting in an overall increased energy consumption, this energy also being fed in continuously must become.

As for the incandescent light sources, these are special a very large light emission spectrum, while the detector generally contains a photodetector that only has can address a reduced section of this spectrum.

In addition, discharge or arc lamps, which can be well selected in terms of their emission spectrum, a relatively high supply voltage is required.

The present invention is primarily intended to provide a smoke detector or fire detector can be created that does not have the disadvantages of using light sources as described was afflicted.

The present invention thus relates to a photoelectric smoke detector with a light source and a photoelectric one Cell, which are arranged in a housing which is sealed against ambient light or external Ltht,

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however, in which the smoke can penetrate, in such a way that the cell is affected, be it by reflection of the light of the Light source, or be it by darkening the latter, further with means for evaluating the signal emitted by the cell. The invention is characterized in that said light source consists of a component in the form of a solid or a liquid, preferably of a semiconductor component consists.

The use of such a component enables not only a greatly reduced energy consumption, a supply with greatly reduced voltage, but also leads to an extended life of the detector.

In order to finally achieve an improvement in the temperature stability and to drift the rest point of the previously described one To avoid detector type, the photoelectric cell preferably has two photoelectric elements and the detector further has the means to influence said elements, respectively, by absorption or by darkening the light emitted by the light source and by reflecting this light with the help of the smoke particles, which can penetrate the housing.

Thanks to these properties, considerable advantages are achieved over known detectors:

The photoelectric elements may be operated in its characteristic range v / ground which a low Ohm ¹ see V / ilerstandswert corresponds and they lead to improved stability of the measurement.

One uses the two phenomena of the at the same time

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Absorption and reflection, which have opposite influences exercise the two photoelectric elements of the cell. This gives considerable sensitivity.

In contrast, the "external" changes (for example Temperature and aging) or their effects on the two elements balanced or compensated; it turns out that that the fluctuations do not affect the rest point of the detector.

Further advantages and details of the invention emerge from the description of exemplary embodiments which now follows referring to the drawing. It shows:

Figure 1 is an axial sectional view of a smoke detector according to a first embodiment of the invention;

FIG. 2 shows an electrical circuit diagram;

FIG. 3 shows a sectional illustration of a smoke detector according to a second embodiment of the invention;

FIG. 4 is a sectional view taken along line 4-4 of FIG. 3; and

FIG. 5 shows an electrical circuit diagram of the detector of FIGS. 3 and 4.

Looking at Figures 1 and 2, you can see a smoke detector, which is carried out according to a / fersten embodiment of the invention and which operates according to the Tyndall effect.

This detector has a cylindrical housing 1, which

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preferably consists of two parts 1a and 1b, which are attached to each other are fastened by suitable means, for example by flanges 2 and a screw-nut arrangement 2a.

The lower section 1a has three circular openings 3 to 5 which are covered by associated screens 3a to 5a are and which are arranged at a certain distance from the wall, such that this creates a labyrinth for the of outside light is formed.

The screens are covered with a black layer, 6, for example a matt coat on the surface that indicates the assigned opening.

However, there are also the openings themselves with black matt Layers 7 bordered in such a way that the light which enters through the openings 3 to 5 when it enters the housing is absorbed, while the smoke can penetrate unhindered if necessary.

Two coaxial sleeves 8 and 9 are attached to the vertical wall of the housing 1. Its axis is perpendicular to the axis of the housing.

The sleeve 8 is used to provide a light source 10 with an associated To hold focusing lens 10a. The sleeve 9 is covered on the inside with an absorbent layer 11, for example one black matt paint.

The light source 10 consists of a component in the form of a solid or in liquid form. Preferably there is they consist of a semiconductor device, such as an electroluminescent diode, whose emission spectrum changes

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generally located in a very narrow band of wavelengths, such as the red range from 0.64 to 0.68 microns, the yellow range from 0.58 to 0.62 microns, or the green range from 0.52 to 0.56 microns. These diodes are obtained when starting from a doped material such as the arsenic of gallium or the phosphorus of gallium, the doping giving the emitted light the required color. One can use, for example, a type of diode manufactured by Hawlett Packard under the designation n ° 5082-4403 , or manufactured by Texas Instruments Inc. under the designation n ° PIL 209 or by General Electric under the name n ° SSL 22.

It is also possible to use certain liquid crystals which have the ability to emit light radiation in the presence of electrical energy.

Such light sources make it possible for the detector to have a very low power consumption, which for an electroluminescent diode is on the order of 20 mW while the required Voltage is on the order of 1 volt.

A printed circuit board 12 is clamped between the flanges 2 of the housing sections 1a and 1b. This shows in her Center has a circular opening 13 in which a pipe section 14 is fastened coaxially to the housing 1, which is attached to his upper end carries a photoelectric cell 15, such as a photoelectric resistor. The response range such a photoelectric resistor is selected as a function of the light source 10 used, so that its Sensitivity is preferably a maximum in the emission range of this source.

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The printed circuit board 12 is connected to three conductors 16 to 18, of which two (16 and 17) ensure the supply of the detector, and of which the third (18) an alarm signal should be transferred.

A monitoring or indicator lamp 19 is in the lower wall of the housing and this enables a visible control of the alarm status of the detector. This monitoring lamp is connected to the printed circuit board via a line 20 tied together.

The components of the detector in the electrical circuit diagram of FIG. 2 are now considered.

The light source 10 is constantly between the feed lines 16 and 17 connected via a stabilization resistor 21.

The photoelectric element 15 is also via a resistor 22 connected to the feed lines 16 and 17 and forms with this resistor a voltage thaler, its division ratio is variable as a function of the excitation of cell 15.

The measurement signal, which at the connection point 23 of the voltage divider is tapped, is applied to a thyristor 24 which is connected in series with the lamp 19. The line 18 is connected to the connection point of these two components.

If smoke now penetrates into the housing 1, the light emitted by the source 10 is reflected by the particles of the smoke and the reflected energy excites the photoelectric cell 15.

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In the absence of smoke, on the other hand, the light from the source becomes complete absorbed by the sleeve 9 and by the black areas of the housing.

If the amount of smoke exceeds a certain threshold, the cell 15 raises the potential at point 23 to a value at which the thyristor 24 turns on or ignites. In this way, the line 18 is returned to the potential of the conductor 17.

The change in this potential can be used to excite a signaling device, in a suitable manner for example a siren or some other device.

According to a modified embodiment, which is not illustrated in the drawings, the cell 15 can be directly opposite the light source 10 -ein, i.e. in the sleeve 9, in such a way that the smoke when the light source is darkened The impedance of this cell changes, so that a fluctuation in the potential at connection point 23 results therefrom.

The circuit according to FIG. 2 can be implemented on the printed circuit board 12 in the usual manner.

In the second embodiment, which is illustrated in FIGS is, the smoke detector has a cylindrical housing 25, which is preferably made of metal and two on each other joined parts 25a and 25b, the part or section 25a having an inwardly projecting edge 26, against which a printed circuit 27 rests. The latter contains the electrical circuit of the detector.

The sections 25a and 25b widen together thanks to the flanges 28

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which is held, a plate 29 being clamped between these flanges which divides the housing 25 into two chambers 30a and 30b, the chamber 30b being the measuring space of the detector. The plates 27 and 29 are held at a distance or in position from one another with the aid of a spacer ring 31.

A photoelectric cell 32 is arranged in the center of the support plate 29 so that it can intercept the light which is present in the measuring space or the measuring chamber 30b. This cell is of the differential type and has two photosensitive cells Elements 33 and 34 on which different light values get abandoned.

The wall of the chamber 30b is perforated with inlet openings 35, through which the smoke can penetrate. These openings are covered by screens 36 which are at a certain distance from the viand of the chamber 30b. The surfaces of these screens pointing towards the outside are more preferred Coated with an absorbent material 37, which is also applied to the inner peripheral edges of the openings 23 is provided. This arrangement prevents the ambient light from entering the chamber 30b. In the wall the latter chamber is further formed a recess 38 in which a light source 39 is arranged, which is from Is solid type or liquid type as described with reference to the first embodiment of the invention. This light source emits light in a direction perpendicular to the axis of the cylindrical housing 25 of the detector and this Light cannot strike the photosensitive elements 33 and 34 directly.

Chamber 30b also contains means for energizing photosensitive elements 33 and 34, respectively, by absorption

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of the light of the source 39 and by reflection of this light on the particles of smoke which can enter the chamber 30b through the openings 35.

These means comprise, on the one hand, a screen 40 which consists of a sheet of opaque material, for example Metal, and is firmly anchored to the wall of the chamber 30b by means of two feet 41. The screen 40 covers the element 34 to the light source 39 and also to the light that comes from this light source and on the walls of the Chamber 30b is reflected.

A plate 42 has a reflective surface 43 and allows it is to capture the light reflected from the walls of the chamber 30b to apply it to the photosensitive member 34 to direct. The plate 42 is arranged to be adjustable with the aid of means for adjusting the position, the one screw 45 which engages in a threaded hole 46 which is provided in the lower wall of the housing 25. These The screw ends in a smooth section 47 which engages a piece of pipe 48 which is firmly attached to the rear surface of the Plate 42 is connected.

It can be seen that when the screw 45 is rotated in the threaded hole 46, the plate is displaced in the vertical direction. With others In other words, you can determine the dimension of the lower portion of the plate 42 by operating the adjusting screw 45, which reflects the light towards the photosensitive element 34, i.e. the portion which passes through the screen 40 is not covered.

It is thus possible, in the absence of smoke in the detector, to precisely compare the amounts of light that the elements 1 and

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34 affect. In the absence of smoke, the amount of light which excites the photosensitive element 33, determined by the reflection of the light emanating from the source 39 and that on the walls of the chamber 30b falls.

However, the amount of light which affects the photosensitive member 34, is determined by the rays which are captured by the plate 42 and which are also via reflection from come from the walls of chamber 30b.

It should be mentioned, however, that neither the element 33 nor the element 34 receive directly the light emitted by the source 39 goes out.

The detector also has a monitoring lamp L ₁ which is arranged in the lower wall of the housing 25.

FIG. 5 shows an example of an electrical circuit which can be used in the detector according to FIGS. 3 and 4. This circuit is fed evenly by current and zv / ar from an excitation source (not shown), which occurs via the lines 49 and 50. The voltage appearing on these two lines is stabilized by a control device consisting of a transistor T ₁ , a resistor R ₁ and a Zener diode Z ₁ , these components being fastened in a conventional manner.

The emitter of the transistor T ₁ is connected to a resistor R ₂ and the latter leads to an electroluminescent diode which represents the light source 39 in FIGS. This electroluminescent diode is also connected to line 50.

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The connection point between the resistor R ₂ and the emitter of the transistor T ₁ is further connected as follows:

Introduced to the photoelectric cell 32, which in the illustrated case consists of two photosensitive elements 33 and 34, in this example of photo resistors;

it also leads to the source connection of a field effect transistor T ₂ ; and to a voltage divider, which consists of a series circuit of a resistor R ₁ , a potentiometer P 1 and a resistor R, the latter being connected to line 50.

The control connection of the transistor T ₂ leads to the connection point between the photoresistive elements 33 and 34, while the drain connection of the field effect transistor Tp is connected to the line 50 via a resistor R ₅ . This resistor also leads to the control connection of a unijunction transistor (release tr ans üors) T, and to line 50.

The cathode of this transistor T ^ leads via a resistor Rg to the line 50, while its anode is connected to the movable tap of the potentiometer P ₁ . The connection point between the resistor Rg and the transistor T- is connected to a tripping device 51, such as a thyristor or an electromechanical relay, by means of which an alarm device located outside the detector can be controlled or actuated via a line 52. The monitoring flap L ₁ is connected between the line 49 and the triggering device 51.

The functionality of this smoke detector is now like folect:

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When a certain amount of smoke enters the interior of the chamber 30b, this is how two specific phenomena arise:

The particles which enter the light beam which originates from the source 39 reflect part of this light towards the photoelectric Elanent 33, which is not is covered;

on the other hand, the smoke particles entering the space delimited by the screen 40 and the walls of the chamber 30b, absorb this through the reflective surface 43 of the plate 42 reflected light.

In this way, the photoelectric cell 32 becomes twofold Subject to effect:

1.) The resistance of the photoelectric element 33 decreases; 2.) the resistance of the photoelectric element 34 increases.

There is thus an inverse effect or a differential effect in the two photosensitive elements compared to the Smoke penetrates into the chamber 30b, thereby increasing the sensitivity of the device to a considerable extent will.

Referring again to FIG. 5, it can be seen that when the resistance of element 33 becomes smaller and that of the element 34 becomes larger, the voltage at the connection point 53 decreases. This voltage, which the high-impedance input, input of the field effect transistor Tp is shown in a low impedance at the output of the field effect transistor Tp. This results in a voltage reduction at the

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Resistance Rc closes and when this decrease one exceeds a certain value (in other words, when the amount of smoke entering the detector has a certain density exceeds), the unijunction transistor T, is excited or switched through and the device 51 is excited. Under these conditions the lamp lights up L ^ up and an alarm signal is transmitted on line 52.

The threshold value to which the detector responds can be set precisely with the aid of the potentiometer PJ, which is present in the voltage divider R ₁ , P 1, R ^.

It should be noted that the arrangement according to the description with respect to the temperature is compensated. If there is an external temperature fluctuation, it is carried over in the same way Shape on the photosensitive members 33 and 34 such that that the connection point 53 remains at a voltage value or fixed point of rest. This is also the case when the Properties of elements 33 and 34, e.g. due to aging, to be changed.

In the described embodiment, photoresistive elements are used used. However, other photosensitive elements can be used and the electronic

Circuit to be adapted accordingly.

According to a modified embodiment that is not in the Drawings illustrated can also be used instead Screen 40 and instead of the reflective plate 42 provide a light source (not shown), which directly the photoresistive element 34 excited. In this case, it is necessary to provide means to enable the photoresistive element 33 to cover this source.

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The detectors according to the invention that use a light source of the type described are equipped, are robust and have a comparison with detectors with incandescent lamps or gas discharge lamps extended service life.

The light sources used also have the advantage that they can be used with a certain modulation in the supply voltage, which creates the possibility of that the signal emitted by the photoelectric cell is coded either in analog form or in digital form can.

All of the technical details that can be seen in the description and illustrated in the drawings are for the Invention of importance.

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Claims (15)

2310A90 - 16 PATENT CLAIMS Π J Photoelectric smoke or fire detector with a light source and a photoelectric cell, which are arranged in a housing and this housing is sealed against the light coming from outside, into which, however, the smoke can penetrate and influence the cell mentioned one by reflecting the light coming from the light source and the other by darkening the latter, the detector being equipped with means to evaluate the signal emitted by the cell, characterized in that the light source (10; 39) consists of a component in solid or liquid state, preferably consists of a semiconductor component. 2. Detector according to claim 1, characterized in that the light source (10; 39) consists of an electroluminescent diode. 3. Detector according to claim 1, characterized in that the light source (10; 39) consists of a liquid crystal. 4. Detector according to one or more of the preceding claims, characterized in that the light source (10) is fastened inside the housing in a holder (8) and opposite an absorbent device (<3) is arranged in which the generated light radiation is sent that further the photoelectric cell (15) at a distance from the one so produced Light path is arranged in such a way that the light energy reflected by the smoke which has penetrated into the housing (1) can be detected is. 5. Detector according to one or more of claims 1 to 3, characterized characterized in that the photoelectric cell (15) in the 309837/045 2 Housing (1) opposite the light source (10) is arranged in such a way that the latter is darkened by the in the housing (1) penetrating smoke can be detected. 6. Detector according to one or more of the preceding claims, characterized in that the light source (10) and the photoelectric cell (15) between two feed lines (16, 17) are connected and that these each have a stabilizing resistor (21, 22) connected upstream, while the connection point (23) of the photoelectric cell (15) with the associated resistor (22) is connected to a thyristor (24) is that when it is switched through the potential on an alarm line (18) in a suitable manner in the event of an increase or alarming increase in the d «s» concentration of the in can change the detector of penetrating smoke. 7. Detector according to claim 6, characterized in that a signaling lamp is connected in series with the thyristor (24) is. 8. Detector according to one or more of claims 1 to 3 _t, characterized in that said cell (32) has two photoelectric elements (33, 34), and that means (40, 42) are provided to the said elements (33 , 34) in each case by absorption or / or darkening of the light originating from the light source (39) and by reflection of this light on the smoke particles that have penetrated into the housing (25). 9. Detector according to claim 8, characterized in that the means for energizing said photoelectric elements (33, 34), each by reflection and absorption, from a screen (40) which is arranged opposite one of the elements (34) 309837/0452 is so that this this element opposite that of the light source (39) emerging light and opposite that from the walls of the housing (25, 25a, 25b, 30b) reflected light is covered, and a reflector device (42, 43) exist, the latter can capture an amount of light that is determined by said light reflection and this amount of light to said photoelectric element (34) reflects back. 10. Detector according to claim 9, characterized in that the reflector device (42, 43) with the aid of a regulating device (45 to 48) is movably arranged such that said amount of light which is reflected back to the photoelectric element (34) is adjustable. 11. Detector according to one or more of claims 1 to 3, characterized in that said cell (32) has two photo-sensitive Having elements (33, 34), one of which (33) is arranged in such a way that it is the one which has entered the detector Smoke reflected light intercepts further a light auxiliary source is provided which directly the second photosensitive element (34) illuminates, so that this catches the light which is caused by the smoke entering the detector is subjected to absorption. 12. Detector according to one or more of claims 8 to 11, characterized in that the photosensitive elements (33, 34) consist of photo resistors. 13. Detector according to claim 12, characterized in that the photoresistors (33, 34) are connected in series to the connections of a voltage source (49, 50, R ₁ , T ₁ , Z ₁ ) and that their connection point to an impedance transformation device (T ₁ ), the output of which is connected to a release device (T ,, 309837/0452 51) is connected. 14. Detector according to claim 13, characterized in that the. Triggering device (T- ,, 51) has means (FU, P ₁ , R ^) for providing a threshold which is exceeded when a certain amount of smoke is present in the detector. 15. Detector according to one or more of the preceding claims, characterized in that the housing (1; 25) with the external environment via one or more light labyrinths (3 to 5, 3a to 5 ^ a, 6, 7). 309837 / CK5 2 Blank page