DE1946379A1 - Device for the detection of reflective particles in a light-permeable medium, in particular for use as a fire and smoke detector - Google Patents

Description

Device for the detection of reflective particles in a transparent medium, especially for use as a fire and smoke detector

The present invention relates essentially to fire and smoke detectors and alarm systems, and in particular one Constant sensitivity alarm device to detect the presence of smoke, steam or other particles in the Ambient air.

A large number of electronic devices have already been installed developed measures to determine the amount of smoke, steam or other particles in a room or area, in order to determine and indicate abnormal conditions resulting from fire, explosions or other dangerous circumstances. The in such devices

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applied circuits were, in general, complicated and expensive and also prone to malfunctions, but they are not were easily brought to the knowledge of the users of the devices. The introduction of transistorized circuits has reduced a number of operational problems, but many difficulties remain, such as for example setting the sensitivity of the alarm circuit, increasing the service life of the components and the Avoidance of failure of the components in critical moments, as well as the display of fire, which is only heat but produces a minimum of smoke.

The present invention has for its object to be a To provide display device with increased reliability, which can also be made heat-sensitive and whose sensitivity remains constant over a long period of use. In addition, alarm signaling devices and a Safety device may be provided.

The present invention comprises a device for indicating smoke formation which has a chamber with a light source and a photocell which detects light from the light source only when it is from in the chamber Particle is reflected, a self-balancing control circuit being provided for actuating an alarm device is. The self-balancing control circuit, which is actuated as soon as the light detector signal of the photocell exceeds a certain level, has a voltage divider bridge arrangement which is used to operate the gate electrode of a controllable rectifier, which controls the flow of current to the alarm device, uses a field-effect transistor equipped with an insulated gate electrode. By means of this

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Bridge arrangement, the sensitivity or the threshold value of the alarm control circuit is kept constant regardless of large changes in the supplied operating voltage. Further characteristics of the gate direction consist of electric circuits' -sr intermittent switching on of the light source and the alarm device, alternating current sources and a safety device for triggering the alarm if the light source has burned out, as well as a setting device for the sensitivity and a device for detecting high temperatures without smoke development .

The invention will then be described with reference to the drawings. Show it:

FIG. 1 shows a side view of a detector chamber according to the invention for vapor or particles,

Figure 2 shows a cross section of the * amBev along the line 2-2 of Figure 1,

FIG. 5 is a schematic circuit diagram of a detector device according to the present invention,

FIG. 4 shows a schematic circuit diagram of another embodiment of a detector device according to the present invention Invention,

FIG. 5 shows a schematic circuit diagram according to the present one Invention, in welelera an amplifier circuit with a self-balancing alarm data circuit is used, wherein a A device that responds to high temperatures and a safety device are provided *,

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FIG. 6 is a schematic circuit diagram of a modified one Embodiment of the present invention,

FIG. 7 shows an echematic functional circuit diagram of another according to the invention Embodiment and

FIG. 0 shows a schematic functional circuit diagram of a further embodiment of the invention in which a speaker is used in the alarm system.

The smoke detector part of the device according to the invention is shown in Figures 1 and 2 and includes a vapor or particle detector chamber 10 consisting of an open ended Cylinder 12 and two end plates 14 »16, which are loose fit over the ends of cylinder 12 and are provided with inwardly directed peripheral flanges 15 and 17, Spring clips 18, which are directed outward at the ends of the cylinder 12, hold the end plates 14 and 16 on the cylinder and the flanges 15 and 17 of the end plates at a radial distance from the wall of the cylinder 12. The entire inner surface of the chamber 10 is to suppress a reflection with painted dull black *

As best seen in Figure 2, there is a light source 20, for example a glow lamp * arranged in a tube 22 which extends radially outward from the wall of the cylinder 12 extends. The tube 22 also has a lens 24 which focuses the light 21 emerging from the glow lamp 20 into a similar tube 26 which is directly diametrically opposite located on the cylinder 12, the light 21 in a

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narrow area on an end cap 28 of the tube 26 is focused. The two tubes 22 maintain a distribution of the light coming from the glow lamp 20 in the main part of the cylinder 12 as little as possible, thereby causing a reflection of light on the cylinder walls is largely prevented.

At right angles to the tubes described above, a third tube 30 is arranged, which extends inward through the wall of the cylinder 12 and at the same time protrudes outward from the cylinder wall. In the outer section of the third tube 30, a photocell 32 is arranged, which can consist of a cadmium sulfide acid, and a lens 34, which is used to direct light, which is reflected by vapor or particles in the cylindrical chamber, onto the cell 32 to focus. The field of view of the lens 34 is larger in that part of the cylinder wall which is diametrically opposite the third tube 30 than in that point at which the light beam 21 emerging from the glow lamp 20 intersects the field of view of the lens 34. The inner section of the tube 30 is cut off at an angle in such a way that the open end of the tube faces away from the glow lamp 20. In addition, part of the open end of the tube 30 is covered by a lip 35 , so that indirect light rays coming from the end cap 28 are not reflected onto the photocell 32.

The detection of smoke takes place essentially in the manner described below. Smoke or other particles, which are present in the space in which the device is located, Ik the cameras 10 enter through openings 18a which are provided between the spring clips 18 of the cylinder 12 and the end plates 14 and 16. Get the smoke or

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the particles in the light beam 21, they become light is reflected on the photocell 32 so that the cell 32 provides a signal indicating the presence of light reflecting particles. As soon as the signal has a certain Threshold value is reached, a suitable circuit, which is connected to the cell 32 via lines 33, a « switched and actuated as a result an alarm device. The assigned operating circuit represents the present invention.

Xm Sinklang with the preceding, improved electrical circuits are provided for operating the glow lamp 20, by which the signal coming from the photocell 32 is amplified and the alarm device is activated. These circuits are shown in Figures 3 to .8, the The circuits of FIGS. 3 and 4 essentially correspond to those described in US patent application Mr. 585 782 des the same applicant are described, including this application a Additional registration (oontlmiation-ln-part)).

The circuit shown in Figure 3 shows the general Arrangement of all individual circuits and includes, in particular, a sawtooth generator circuit with a double base diode, which is shown in the left part of the figure and the one for controlling the light source «for example the Qllmmlamp 20a» serves. On the right-hand side of the figure, a gate and amplifier circuit is provided for increasing the signal strength of the signals supplied by the photocell 32 to an alarm horn 36 will. In the upper middle section of the figure is a circuit for resetting the gate circuit to its starting position intended.

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In the oscillator part of the circuit, the capacitor 42 is slowly charged during normal operation by a current flow coming from the battery 84, this current flowing through the resistor 40 until the breakdown voltage of the double base diode 38 (unijunction transistor) is reached. At this point in time, capacitor 42 is suddenly discharged through dual base diode 38 and resistor 44, generating a current pulse through resistor 44 and a voltage pulse across resistor 40. The resistor 43 is used to apply a gate voltage to the base of the double base diode 38. Part of the current pulses passing through the double base diode are branched and passed through a resistor 46 to the cathode gate of a controllable rectifier 48. The rectifier 48 is activated by this pulse and works as a switch to provide the correct current and voltage for the to supply intermittent switching on of the glow lamp 20a. By selecting appropriate circuit parameters, the pulse rate can be set to approximately one pulse per second.

The oscillator circuit shown in this embodiment is particularly suitable for use with a long-life glow lamp and when the glow lamp is actually switched on 20a is done in the manner described below. As the capacitor 42 charges, the capacitor becomes 50 simultaneously charged through resistor 52. The controllable rectifier is located during the charging time 48 in the "carrion" state. As soon as a current pulse at the cathode gate arrives, the rectifier 48 switches instantly into the "on ^ -Zuatand and discharges the capacitor 50 via a Transformer 54, which by induction the glow lamp 20a

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charges until their ignition voltage is reached. If the capacitor is fully discharged 50 so 54 produces the transformer, a small charge of opposite polarity on the capacitor 50, which in turn inverted to a "voltage ¹ PolaritSt performs at Oleichrichter 48, wherein the oil-calibrated rectifiers ^ in its" off Zuetand is switched * The final charging cycle The lamp 20a is thus switched on intermittently in a time sequence which can be set or readjusted by changing the circuit parameters of the oscillator. .

If light pulses coming from the glow lamp 20a are reflected by belly or steam or the like, they reach the photocell 32. The photocell 32 forms part of an amplifier and alarm actuation circuit. The light falling on cell 32 reduces its resistance, so that as a result a display current flows to the base of a current-amplifying transistor 56, which is biased by a current flowing through resistors 58, 60 and 62. The initial voltage current determines the sensitivity of the transistor 56 to the current coming from the photocell and can be _{adjusted (} by setting the variable resistor 58 to a value corresponding to a maximum sensitivity? ”It was also evident that the pulsed emitter current in the conductive state of transistor 56 flows through resistors 64 and 66 and a potential in pulse form builds up at capacitor 68, which leads to a higher input impedance for current pulses that pass through the input circuit to the base of transistor 56. Resistor 70 limits the maximum current flow through the Traneistor 56 »while capacitor 72 is higher

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Permits current peaks when the current pulses arrive at the base. Therefore, when the signal coming from the photocell 32 reaches a given threshold value, the transistor 56 becomes conductive and delivers an amplified current pulse which appears at the cathode gate of the controllable rectifier 74. The controllable rectifier 74 switches instantaneously into its "on" state when the amplified by the transistor 56 incoming current arrives at its cathode gate. As a result of the conductivity of the controllable rectifier 74, current arrives to the alarm device or horn 36 so that a corresponding alarm is generated.

Since the horn 36 is operated by an interrupter device working in rapid succession, which generates an intermittent flow of current through the horn 36, the current supplied to the anode of the controllable rectifier 74 is pulsed at a higher frequency than the gate current transmitted to the photocall 32. As a result, the controllable rectifier was switched off immediately after each pulse (gating). To prevent this, a transistor 76 is provided which supplies a holding current for the controllable rectifier 74 via the resistor 78, so that the rectifier 74 during the period in which the current flowing through the horn 36 decreases to zero "An ^H state remains. The resistor 80 allows a current flow, which is used to bias the base of the transistor 76, so that the transistor 76 remains in the saturated state and supplies the required holding current. The signal horn 36 is operated and emits in this way." an alarm when the photocell 32 is activated sufficiently to turn on the magnifier 56. The alarm is usually given until the controllable rectifier 74 turns off.

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An intermittently given alarm can, however, be provided by providing a bridge circuit or a capacitor 82 which is located between the controllable rectifier 48 and the transistor 76. As soon as the rectifier 48 supplies a current pulse, its anode voltage changes immediately to a word below the Brdpotentiale, as a result of which a very positive negative current flows through the capacitor 82 on the base of the transistor 76. Characterized through the transistor 76 "to controllable rectifier 74 Bugeftthrte Baltestrom is turned off, if the horn 36 su this time receives no current, the controlled rectifier 74 switches instantly to its ^tt From ^N state and remains in this state" until another current pulse its cathode gate is suggested. If current is passed through the horn 36, the alarm is maintained until the transistor 76 and the horn 36 are switched off at the same time. As long as the photocell 32 delivers a signal, the alarm is given again. In this way, the signal horn 36 can emit an alarm in the form of a pulse, which arouses greater attention.

The battery 84, which serves as the power source for the circuit, only needs to be of a modest size in order to operate the door direction for months enable, if the correct values for the one Parts of the circuit can be selected around that of the Lnpe 20a Reduce the current to a minimum, since the Lamp 20a is only switched on intermittently. Furthermore, the use of a long-life glow lamp increases the Reliability of the detector device.

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A simpler form of presentation is described above The circuit is shown in FIG. Here is a multivibrator or square wave OeBillator sun intermittentP Operation of a conventional incandescent lamp 20b is used. The generator circuit comprises two transistors 86 and 94 with base biasing resistors 92 and 96 and coupling capacitors 90 and ? 8 on. Sin output resistance 100 is connected to the emitters of the two transistors. Transistor 86 in the left section of the circle has a resistor 88, which with is connected to its collector, while lamp 20b is connected to the collector of transistor 94 in the right portion of the circuit. The right section is conductive so the lamp 20b will light up and, as soon as the line passes over the transistor 86 to the left section, the Lamp 20b switched off. As before, the values of the circuit components can be selected to achieve a desired flashing speed *

The gain circuit according to F'f ^ 4 is essentially the same as was described in connection with FIG. 3, with the exception that the transistor supplying the holding current 76 and the reset circuit are omitted. In their place a shunt capacitor 79 occurs for the horn 36.

While the two circuits shown in Figures 3 and 4 result in relatively simple and inexpensive, but effective alarm systems, their sensitivity is through Changes in the supply voltage impaired. This is particularly important when the devices are operated by batteries for an extended period of time as the Battery voltage is decreased and the amplifier bias voltage changes. The reliability of the device

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therefore decreases over time, which is of course undesirable.

A simplified circuit for operating the detector device, which has improved reliability and constant sensitivity notwithstanding significant Has changes in the supply voltage is shown in FIG. This circuit can be used in conjunction with a Battery or optionally with a 115 volt, 60 Hz voltage source and is designed to be heat-sensitive, in order to reach high temperatures, which are accompanied by a breath, to address; The arrangement also has a safety device for emitting a signal when the lamp 20b has blown.

As can be seen from Figure 5, the light source 20b k @ is used in oscillator or multivibrator for the Irapulsehickung, but the light source 20b lights constantly and is fed directly from a battery 84 or possibly a 115 volt voltage source 101 via a transformer 102. A diode 150 and a resistor 151 protect the battery 84 from the alternating current coming from the transformer 102. The current conducted to the photocell 32 is rectified by a diode 118 operating as a single-wave oil rectifier, a protective filter with a capacitor and a resistor 133 being provided. The hi-fi cell 32 is arranged in a voltage divider bridge arrangement together with a field effect transistor 104 with an insulated gate electrode. The bridge arrangement includes the photo loop, which is connected to the base of the field effect transistor 104 together with a voltage resistor 106,

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wherein resistors 108 and 110 are further connected to the field effect transistor 104. The output terminal or drain electrode of the field effect transistor 104 is connected via the resistor 108 to the gate electrode of the controllable rectifier 114 which controls the flow of current through the horn 36.

Gleiehstromlei-9tun3 received by the half-wave rectifier circuit contains an alternating voltage pulse of a predetermined value Waveform and voltage on which the DC voltage supply voltage is superimposed. By selecting suitable resistance-capacitance parameters for the rectifier 118, the capacitor 112 and the low-resistance load on the bridge arrangement a pulse height is obtained for the Y leading edge of the time rise in connection with the pulse height of the waveform, which is controlled by the resistance of the photocell 32. de »can. For example, if the photocell 32 is exposed to light, so that it comes out of the dark area When resistance comes out, it responds much more quickly to a given change in the light-resistance characteristic. This response is added to the superimposed AC voltage component and allows it to reach a threshold value with respect to the field effect transistor 104. on This catfish is effective both a DC and a Weeheelspannungs bias on the photocell 32 to one controlled pulse of sufficient height to generate the switching of the controllable rectifier 114 in the following described manner is used.

If light falls on the photocell 32, the increased Conductivity is a threshold value through which the field effect tran-

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gistor 104 is switched. The opening of the transistor in turn switches the controllable rectifier 114. Therefore a current flows through the horn 36 to issue an alarm. The current flowing through the signal horn 36 is rectified by the controllable rectifier 114 in single-wave operation, this rectifier by the alternating voltage is continuously reset by the transformer 102.

As can be seen, apart from the improved bias, as a result of the inherent automatic gain control provided by the field effect transistor 104 automatically compensates for significant changes in the applied voltage that sometimes occur in the normal voltage sources or batteries occur without the sensitivity being impaired. This improvement the constant sensitivity is achieved with a smaller number of circuit components.

The circuit can also respond to high temperatures unaccompanied by smoke by placing a heat sensitive switch 116 in parallel with controllable rectifier 114 . The switch 116 can be used as a Bi- :. Metal containers may be formed and allows for its actuation a uniform current flow through as ^ ^ horn 36 to emit a signal Dej instead of the rectified current through the controllable rectifier 114 signal generated.

The light source 20b used in this arrangement is permanent, switched on and can be used as an indication that the device is in operation. If the lamp 20b fails , a relay 119 is switched on, which controls the switch

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120 closes and a battery 122 in the circuit this Signal horn 36 inserts. Therefore, a uniform signal is given until the battery 122 is disconnected or the Lamp is replaced.

iin modified circuit, which essentially the Combined circuits of Figures 4 and 5, is shown in Figure 6 and has the features and advantages of the two mentioned Circuits on. Again, a double power supply can be provided, which is connected from the power network 101 with a transformer 102 and a battery 84. These current sources are in parallel with diode 150 and the resistor 151 arranged in the battery circuit, so that the battery in the waiting position is charged when the mains connection 101 is engaged. The scarf" The T6G is used to connect to the network 101 to manufacture.

The multivibrator or square wave oscillator according to FIG. 4 is used for the intermittent operation of the light source 20b. Another improvement in this oscillator circuit consists of a Zener diode 124 ₀ which is parallel to lamp 20b. The scene »-3Di © de 124 precisely regulates the voltage at the lamp 20b, so that the lighting intensity does not differ with the supply voltage. This means that both the lamp supply circuits and the amplifier circuits are spanrrangskompensiöp-t.

35 FeideffeVt-fPrattsistor 104, the controllable rectifier 114, the heat-sensitive holder 116 and the bridge resistors 10fo, 108 vwS 110 are connected in the same way as can be seen from FIG. An additional transistor 126 with a base

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Bias resistor 127 is across a resistor 128 parallel sum horn 36. This transistor 126 has the Task of intermittently short-ringing the horn 36, so that the alarm is switched off and, in the presence of smoke, the horn 36 intermittently with the frequency of light source 20b acting like a flash is operated «Another shunt with a capacitor 130 and a Resistor 132 is provided as a shunt filter for occasional voltage peaks that can occur on the mains or on the battery 64 which is in the waiting position.

Another embodiment of a smoke detector is shown in FIG. In this embodiment, the glow lamp 20a and the incandescent lamp 20b replaced by a radioactive light source 20c, for example with a commercially available self-luminous light source with activated tritium or the like. Light sources of this design are below registered trademark Betalight (manufactured by Ganrad Precision Industries of New York).

The self-luminous light source 20c does not require an external one Current source and can, for example, in the circuit shown in Figure 6 by using a further field effect trans istor- ¥ gain level in the gate circle of the controllable Rectifier 114 can be used. The two stages include the field effect transistors 104a and 104b with their associated bias resistors 108, 110a and 108b, HOb. The power requirement of the device is reduced in this way by using the independent light source 20c, while the operational safety is increased.

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Palls it is desired to power the device only by a battery can be operated with an improved photocell bias by using a Dappeibase diode oscillator 170 in Connection to a filter capacitor 171 takes place instead of the mains connection 101. The double base diode oscillator 170 delivers an additional bias voltage pulse to the supply voltage of the battery 84, whereby the photocell 32 and the amplifier arrangement becomes more sensitive to incident light.

The alarm control of the circuit also includes a Variable resistor 158, which is used to change the bias at the gate electrode of the field effect transistor 104a for Adjustment of the sensitivity of the device can be used. By changing resistor 138, the user can reduce the sensitivity of the device during areas where normal smoke concentration increases, for example while smoking cigarettes in the course of a meeting or a meeting Takes place, which is equipped with the detector.

The modified embodiment of the invention shown in Figure 8 is for use with a speaker 146 in place a bugle determined.

In this case, it is the one used to control the lamp 20b Multivibrator the same «as described in connection with fig using a diode 136 between the base and emitter of the transistor 86 is to work as a voltage limiting device au, that protects the transistor 86 against excessive negative pulses.

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The amplifier part of the circuit is modified so that the controllable rectifier 114 operates the oscillator 140 which uses the loudspeaker 146 to output the alarm feeds the signal. The © scillator circuit 140 contains transistors 141 and 144 used for amplification in connection with the double base diode142, which controls the oscillator » determined at the beginning.

Resistors 141a, 141b, 141c, 142a, 142b, 144a and 144b together with capacitors 143, H5 and 147 provide the rieh = term bias for the oscillator 140. As can be seen, either the speaker 146 or the horn 36 replaced by suitable electronic device capable of emitting a high intensity audible signal.

The invention provides an improved smoke and heat detector device which requires very little power to operate and which can be designed to be self-compensating over a wide range of changes in the applied voltage, and which can also be easily modified in various ways to deliver alarm signals »Ei © device can be operated via the mains or a battery and is equipped with a safety device and a fg.raefülleinrichtung. All of these improved features are achieved with a comparatively simple and inexpensive circuit that required few components

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Claims (9)

. ·. * ■ I1L 2 claims 1. ) Device for the detection of reflective particles in a light-permeable medium, with (a) a light source for projecting a beam of light through the medium and (b) a photosensitive device which receives at least a portion of the light beam when it comes from Particles are reflected that are in the said medium, whereby a first signal is generated, marked by (C) a field effect transistor, which is arranged in a circuit with the phot © sensitive device and is opened when the first signal exceeds a threshold value and (d) a controllable rectifier, which is in a circuit with the field effect transistor and through the opening of the field effect transistor is switched to generate a second signal. 2. Apparatus according to claim 1, with a device for supplying a bias voltage to the photosensitive device, marked by: (e) means for generating an oscillating voltage and (f) a half-wave rectifier associated with the device for generating the oscillating voltage and the photosensitive device is in a circuit in such a way that the bias voltage is both equal to current as well as an impulse component. - 19 0098 19/1322 BAD OR.G.NAU • · «II • · a • · · ■ • «ι 3. Apparatus according to claim 2, characterized in that the device for generating an oscillating voltage is parallel to the controllable Sieichrichter. 4. Device according to one of claims 1 to 3 $ characterized by an alarm device which is actuated by the second signal. 5. Device according to one of claims 1 to 4, characterized by means of intermittent operation of the light source. 6. Apparatus according to claim 5 »characterized in that the device for operating the light source has the following parts having: (e) a multivibrator to one input section of which the light source is connected and (f) a Zener diode that is parallel to the light source. 7. ' Device according to one of claims 1 to 4, characterized ge = indicates that the light source consists of a self-luminous radioactive light source. 8. Device according to one of claims 1 to 7, characterized by a heat-sensitive switch, the parallel to the controllable rectifier. 9. Photosensitive detector, characterized by (a) a photo cell, Cb) an oscillator to provide a bias voltage for the photocell and . - 20 - 009819/1322 -al- [c) a Einweggeliehriühter, which is in the circuit with the The oscillator and the photocell is located, the bias voltage having both a direct current component and a Pulse component has. 21 «. BATH ORIGINAL VL Blank page