EP2734988B1 - Pulse-operated smoke detector with digital control unit - Google Patents

Description

The invention relates to an open type smoke detector ("smoke detector") comprising at least one pulse operated light emitting element and at least one light sensing element in an open housing and a power supply unit connected to the light emitting element or elements.

The technical field of smoke detectors is characterized by a high level of sophistication and includes various types of smoke detectors, most notably those of the closed type (having a substantially closed detection chamber) and those of the open type (having a space open housing).

From the Applicant's point of view, in the extensive state of the art, insofar as it relates to individual smoke detectors, the following publications are worth mentioning in particular: WO2005069242 . GB2410085 . DE10104861 . DE10118913 . DE19951403 . WO2008017698 . US2004 / 0066512 . US6218950 . US2008 / 0246623 . DE19809896 . US2002 / 0080040 . WO9916033 . US2006 / 0202847 . WO2004032083 . WO1995004338 . WO2006024960 . GB2319604 and EP1619640 ,

Of the patent literature dealing with more complex smoke detection systems, the following references appear to the applicant as worth mentioning: US6075447 . EP1555642 . GB2357358 . WO1993015483 . DE19740922 . GB2293472 . US6195011 and US20050219045 ,

In the WO 2005069242 a smoke detector is described which operates according to the scattered radiation principle and comprises at least one radiation transmitter and at least one radiation receiver whose radiation paths penetrate a scattering volume. Two pairs of radiation transmitters / receivers are used which form two separate scattering volumes at the same distance from the detector surface. The fire detector also includes a pair of radiation transmitters / radiation receivers for dust compensation.

In the GB 2410085 a smoke detector is described which has a shielding cover window to protect the radiation transmitter and radiation receiver. There is a special feature described in the cover window, which excludes waveguiding effects in the window and prevents light from passing directly to the radiation receiver, without being scattered in the controlled volume.

In the DE 10104861 a smoke detector with detection chamber is described which operates according to the scattered and transmitted light radiation principles. This detector is available as a variant for detection in a free space litter volume without a detection chamber. The detector has automatic compensation for stable levels of smoke, dust on its surface.

In the DE 10118913 For example, there is described a free-space scattered light type smoke detector having a plurality of detection volumes organized by a system of lenses and radiation emitter and radiation receiver arrays.

In the WO 2008017698 a smoke detector is described which uses two different wavelengths for smoke detection and detection between different types of smoke. Two different receivers are directed at different angles on the transmitter central axis.

Out EP 0 618 555 There is known a smoke detector comprising at least one pulse operated light emitting element, at least one light sensing element in an open housing, and a power supply unit connected to the light emitting element and the voltage stabilizing means, an energy harvesting device, and a digital operation monitoring and control unit for monitoring and controlling the operation of the power supply unit and thus of the light-emitting element, wherein the control unit is designed for real-time control of a switch-on and a pulse duration of the light-emitting element.

Out DE 2632876 A1 is a smoke detector of the open type known.

In the US 20040066512 a smoke detector is described with a smoke chamber having two emitting diodes in different spectral ranges, preferably for IR (about 880 nm) and blue light (about 400 nm), and two receiving diodes. The transmitting and receiving diodes are at different angles on a flat surface so that forwardly scattered radiation reaches a receiving diode and backscattered radiation reaches the other receiving diode. The detector has good performance for both white and black smoke.

In the US 20080246623 In the US Pat. No. 4,843,809, an open type smoke detector is described in which two emission elements are arranged at different angles and polarization planes are used to distinguish between different types of scattered radiation from the controlled region.

In the EP 1619640 a smoke detector of the open type is described with a very simple circuit arrangement in which two signals from two Emission diodes are measured at different angles. The main process steps are performed by a microprocessor. There is also a temperature sensor provided.

Out EP 0 094 534 A1 or EP 0 571 843 A1 In each case, smoke detectors are known in which energy collection devices are arranged in the driver circuit of the light-emitting element.

The invention has for its object to provide an improved smoke detector of the type described above, which operates precise and reliable under various conditions of use.

This object is achieved by a smoke detector with the features of claim 1. Advantageous developments of the inventive concept are the subject of the dependent claims.

The invention includes the idea that the power supply unit comprises voltage stabilization means and an energy collection device and a digital operation monitoring and control unit for monitoring and controlling the operation of the power supply unit and thus of the light emitting element or elements. Furthermore, the invention includes the idea of forming the digital operation monitoring and control unit for real-time control of a turn-on time and a pulse duration of the light-emitting element or elements in response to a temperature signal.

In one embodiment, the smoke detector has at least one built-in temperature sensor connected to a T-sensor input of the digital operation monitoring and control unit. In a further embodiment of the invention it is provided that the power supply unit comprises current stabilizing means, which are arranged on an output side of the energy collecting device and connected to the operation monitoring and control unit via a control line to be controlled by the operation monitoring and control unit.

In an advantageous manner, the power supply unit can furthermore be designed to supply the light-emitting element or the elements with sinusoidal pulses.

This advantageously makes it possible to use narrow-band filters in which sinusoidal signals produce no or only small parasitic signals. The signal shape is realized in particular by digital means, using a digital-to-analog converter.

In a further embodiment, the operation monitoring and control unit comprises interference signal monitoring means for optically monitoring the detection area, and is adapted to supply the light emitting element or elements at intervals with supply pulses in which external optical noise is below a value above has a predetermined period of certain average value. In a Embodiment, the Betriebsüberwachungs- and control unit is adapted to store a over a predetermined monitoring period in the absence of a smoke detection signal detected optical signal, which in particular contains reflection signals from the structural environment of the smoke detector, as a background interference signal and in a compensation control of Operation of the light-emitting element or elements to use. In a further embodiment, it is provided that the operation monitoring and control unit for compensating control of the light-emitting element or of the elements operates with signals of the same pulse shape as are provided for their operation without compensation control.

With the aforementioned embodiments, a reliable, especially dynamic, smoke density detection under adverse conditions, such as in environments with strong reflection effects or in emergency situations where forest fires bring a massive exposure to smoke over long periods, aims. With the last-mentioned embodiment, a simple and fast signal acquisition is made possible, dispensing with somewhat more time-consuming digital combination methods.

In another expedient embodiment of the invention, the light emitting element or elements provide an emission signal in at least two different spectral regions, and the light sensing element or light sensing elements are adapted for signal detection in all emission spectral regions used. In particular, this embodiment makes reliable smoke detection possible even if the smoke detector is under the direct influence of sunlight and / or a black or white smoke is to be detected and, if necessary, to be distinguished from one another.

In another preferred embodiment, the smoke detector has a built-in flame detector connected to a flame detector input of the operation monitoring and control unit, the operation monitoring and control unit configured to control a detector operation in response to a signal from the flame detector is. Specifically, the flame detector has a UV-type and / or IR-type detector.

In a further expedient embodiment, the proposed smoke detector has three or more LEDs which are arranged in a common plane on a hyperbolic or spiral curve with respect to the light detection element or the light detection elements.

In further embodiments of the invention, the smoke detector comprises a test light-emitting element which is provided and designed exclusively for operation for test purposes, and / or a calibration light-sensing element which is provided and configured exclusively for the purpose of operation, with which signals the light sensing element or the light sensing elements are calibrated. In an embodiment of this latter embodiment, it is provided that the open housing has at least one light-reflecting surface which is designed to form a light path between the light-emitting element and the light-detecting element and the calibration light-detecting element in order to effect a dust correction of the detector signals.

According to another construction aspect of the proposed smoke detector, light emitting elements are provided in the direct detection range of light detecting elements on the same optical axis. Here, a first pair of a first light-emitting element and a first light-sensing element is then enclosed in a hermetically sealed housing and a second pair of a second light-emitting element and a second light-sensing element arranged in the open housing. Furthermore, an evaluation unit for receiving the signals of the first and second element pair and for processing the signals of the first pair for noise compensation of the signals of the second element pair is formed.

In further embodiments, the smoke detector has at least one sensor input, in particular a multimodal optical fiber input, for connection the smoke detector with an external sensor element, in particular an external temperature sensor and / or external flame detector.

• Senkung der Möglichkeit falscher Alarme.
• Anheben der Empfindlichkeit des Melders für echten Rauch.
• Bereitstellen einer schnelleren Erfassung in frühen Brandstadien.
• Garantieren einer Immunität gegen optische Signale und Funkrauschsignale
• Erhöhen der Raucherfassungsstabilität unter schwierigen Bedingungen, einschließlich Lichtstrahlung mit hohem Pegel und Hindernissen im Erfassungsbereich.
• Bereitstellen präziser Daten an den Benutzer, z.B. Rauchdichtedaten für technologische Messung und Steuersysteme.
• Ausschließen von Störungen, die z.B. durch zufälligen Zigarettenrauch oder beständigen Rauch aus Waldbränden verursacht werden.
• Überwachung der Rauchdichteverteilung im Inneren des gesamten Gebäudes für eine sichere Evakuierung von Menschen.
• Einführen einer ultra-schnellen Branderfassung auf Grundlage einer Bestätigung verschiedener Arten von Meldern (Rauch, UV-Flammen, IR-Flammen, Temperatur)
• Bereitstellen eines besseren Staubausgleichs.
• Erweiterung des Betriebstemperaturbereichs des Melders.
• Sicherstellen der Sicherheit menschlicher Augen in allen Betriebsarten. Energieeinsparung.

With the invention, at least in certain advantageous embodiments, one or more of the following advantageous effects can be achieved:

• Reduction of the possibility of false alarms.
• Increasing the sensitivity of the detector for real smoke.
• Providing a faster detection in early fire stages.
• Guaranteeing immunity to optical signals and radio noise signals
• Increase the smoke detection stability in difficult conditions, including high-level light radiation and obstacles in the detection area.
• Provide accurate data to the user, eg smoke density data for technological measurement and control systems.
• Excluding disorders caused, for example, by accidental cigarette smoke or constant smoke from forest fires.
• Monitoring the smoke density distribution inside the entire building for safe evacuation of people.
• Introduce ultra-fast fire detection based on confirmation of various types of detectors (smoke, UV flames, IR flames, temperature)
• Provide a better dust balance.
• Extension of the operating temperature range of the detector.
• Ensure the safety of human eyes in all modes. Energy saving.

• Fig. 1 ein Funktionsdiagram eines Ausführungsbeispiels des Rauchdetektors,
• Fig. 2 eine Realisierungs-Variante der Spannungsstabilisierungsmittel beim Rauchdetektor nach Fig. 1,
• Fig. 3 eine detaillierte Darstellung von analogen und digitalen Baugruppen des Rauchdetektors nach Fig. 1,
• Fig. 4 eine Prinzipskizze zur Erläuterung einer beispielhaften geometrischen Konfiguration wesentlicher Elemente des Rauchdetektors,
• Fig. 5 eine weitere Darstellung, in Art einer perspektivischen Darstellung, zur Erläuterung der geometrischen Konfiguration,
• Fig. 6 eine kombinierte Darstellung zur weiteren Erläuterung der geometrischen Konfiguration,
• Fig. 7A bis 7C weitere Darstellungen zur Erläuterung des mechanischen Aufbaus einer Ausführungsform des erfindungsgemäßen Rauchdetektors,
• Fig. 8 eine Prinzipskizze der geometrischen Konfiguration einer weiteren Ausführungsform,
• Fig. 9 eine weitere Darstellung, in Art einer perspektivischen Darstellung, zur Erläuterung dieser geometrischen Konfiguration,
• Fig. 10 eine kombinierte Darstellung zur weiteren Erläuterung der geometrischen Konfiguration gemäß Fig. 9,
• Fig. 11 eine kombinierte Darstellung einer gegenüber Fig. 10 modifizierten Ausführungsform,
• Fig. 12 eine Prinzipskizze der geometrischen Konfiguration einer weiteren Ausführungsform,
• Fig. 13 eine Prinzipskizze der geometrischen Konfiguration einer weiteren Ausführungsform,
• Fig. 14 eine Prinzipskizze der geometrischen Konfiguration einer weiteren Ausführungsform,
• Fig. 15 eine Prinzipskizze der geometrischen Konfiguration einer weiteren Ausführungsform,
• Fig. 16 eine Prinzipskizze der geometrischen Konfiguration einer weiteren Ausführungsform,
• Fig. 17 eine Prinzipdarstellung eines mehrteilig aufgebauten Rauchdetektors als Teil eines Rauchdetektionssystems,
• Fig. 18 eine weitere Prinzipdarstellung eines mehrteilig aufgebauten Rauchdetektors als Teil eines Rauchdetektionssystems und
• Fig. 19 eine Prinzipskizze einer Ausführungsform eines neuartigen Rauchdetektionssystems.
• Fig. 1 zeigt den grundsätzlichen Aufbau eines erfindungsgemäßen Rauchdetektors SD1.

Advantages and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to FIGS. From these show:

• Fig. 1 a functional diagram of an embodiment of the smoke detector,
• Fig. 2 a realization variant of the voltage stabilizing means in the smoke detector according to Fig. 1 .
• Fig. 3 a detailed representation of analog and digital assemblies of the smoke detector according to Fig. 1 .
• Fig. 4 a schematic diagram for explaining an exemplary geometric configuration of essential elements of the smoke detector,
• Fig. 5 a further representation, in the manner of a perspective representation, for explaining the geometric configuration,
• Fig. 6 a combined representation to further explain the geometric configuration,
• Figs. 7A to 7C further illustrations for explaining the mechanical structure of an embodiment of the smoke detector according to the invention,
• Fig. 8 a schematic diagram of the geometric configuration of another embodiment,
• Fig. 9 a further representation, in the manner of a perspective representation, for explaining this geometric configuration,
• Fig. 10 a combined representation for further explanation of the geometric configuration according to Fig. 9 .
• Fig. 11 a combined representation of one opposite Fig. 10 modified embodiment,
• Fig. 12 a schematic diagram of the geometric configuration of another embodiment,
• Fig. 13 a schematic diagram of the geometric configuration of another embodiment,
• Fig. 14 a schematic diagram of the geometric configuration of another embodiment,
• Fig. 15 a schematic diagram of the geometric configuration of another embodiment,
• Fig. 16 a schematic diagram of the geometric configuration of another embodiment,
• Fig. 17 a schematic representation of a multi-part smoke detector as part of a smoke detection system,
• Fig. 18 a further schematic representation of a multi-part constructed smoke detector as part of a smoke detection system and
• Fig. 19 a schematic diagram of an embodiment of a novel smoke detection system.
• Fig. 1 shows the basic structure of a smoke detector according to the invention SD1.

A power supply voltage Vin is applied to the voltage stabilizer STV1 and an energy storage circuit PAC. The voltage stabilizer STV1 is necessary if we have a power supply from a network in which the voltage can change over time. The STV 1 is connected to a digital unit DU. A new feature of this technical solution is that the DU digital unit can monitor the power supply in the STV1 and the PAC via an analog-to-digital converter ADC and take over power supply management.

An important application is eg in Fig. 2 shown. The switch-on switching elements KE1, KE2, KE3, KE4 automatically switch on, and the supply voltage reaches the voltage stabilizer STV and the digital unit DU. The main switching element KE turns off, whereby the analog unit AU is disconnected. A microprocessor MP in the DU now receives power and begins operation. The MP then waits until the storage capacitors C1 and C2 are fully charged, and turns off the switching elements KE1 and KE4. Thus, the whole circuit receives only from the storage capacitor C1 a supply which is disconnected from the network. The MP analyzes the voltage applied to C1 via the ADC, and when it reaches a certain minimum level, the MP turns off the switching elements KE2, KE2 and then the switching elements KE1, KE4. Now the whole circuit receives only from the storage capacitor C2 a supply.

Voltage divider VD 1 and voltage divider VD 2 use operational amplifiers to bring a split supply voltage into the operating range of the ADC. The operational amplifiers achieve better energy savings in this case than sharing voltage with a pair of resistors, although one can go that way. The resistors R2 and R4 are the same and they can be sufficiently different from R1 and R3. This makes it possible to minimize the power consumption from the line and to make the consumption more even without peaks in the supply line. For example, the power consumption of the DU is low when the MP is busy with simple tasks, and the MP can get power from the C1 for a fairly long time and seldom switches to the C2. But then the MP has to perform a smoke density measurement and switches the supply to the freshly charged C2, then turns on the main switching element KE so that the analog unit AU can operate and then the measurement takes place. In this case, the use of energy from the C2 is much stronger than from the C1 and has a sufficiently shorter duration. As a result, there is an even consumption from the external source, and this power consumption is constantly controlled.

The smoke detector can draw its power from a battery, and the battery voltage is constantly measured by the MP to alert a user when it reaches its limit. By the analog unit by means of the main switching element KE is turned off, the MP achieves a high power saving, and if long-life lithium batteries are used, 5 years of operation can be guaranteed without battery replacement. It is planned to use solar panels for even better power savings and operation without mains connection.

An important aspect is that the digital unit DU can be disconnected from the analog unit AU so that any radio frequency from the microprocessor does not transition to the supply for the AU and also an abrupt switching of MP terminals does not cause jumps in the AU supply level leads. This is in Fig. 2 not shown, but the AU can also be powered by its own storage capacitors and its own voltage stabilizer, managed by the MP in the STV1. Sometimes it is useful and even necessary to disconnect the digital power supply from the analogue power supply for better results. It should be noted that in the basic modification, the power supply for the DU and AU should come from one source, because this circuit performs well in a normal environment, but in heavy industrial applications this is an important decision. It also helps to protect the device from leaps of current, for example, when someone uses a mobile phone near the utility line or when there are EMI and RFI radiations in an industrial location. Even if a lightning strikes the power line, the device is safe and can be easily repaired.

Furthermore, the microprocessor MP performs power management on the power storage circuit PAC. This circuit has storage capacitors and is intended for powering light-emitting elements. It is necessary for the emitting diodes to receive a high current from the power storage circuit PAC for a short time. Such a high current may make the voltage in a supply line low and may even exceed the battery resources when powering a device therefrom. That's why power storage and management is so necessary in this case.

The digital unit DU turns on, then the analog unit AU turns on and operates for a certain time to obtain stable results, then the MP searches for a timing suitable for measurements, and only after that the light emitting elements become simultaneously controlling the current level switched on. The switching of light-emitting elements during a short series of pulses is known per se. What is new about the proposed device is that the pulse duration is used to achieve one and the same performance for the measurement circuit in a very broad temperature range.

In order to get a high accuracy in the measurements, one should amplify the signal, and it is much better to use narrow band filters in all amplifiers, so that only pulses with a specifically set duration could pass out of the light emitting elements. This protects the device from EMI noise. The fact that the filters are tuned to a specific frequency makes it possible for their performance to be more responsive to the increase in temperature. In fact, it always happens that filters tuned at + 25 ° C for a certain frequency will not work at that frequency at + 100 ° C (and also at -50 ° C). This is the reason why it is suggested (see below) to calibrate the duration of pulses with temperature and to change the specific frequency of light pulses so that they always pass through the filters and amplifiers throughout the temperature range. The MP does this work by transferring data to the power storage circuit PAC and to the power stabilizer STC.

• Man stellt viele Detektoren (15 bis 30 auf einmal) zur Kalibrierung in einen ziemlich großen Raum (nicht wie gewöhnlich in ein Rauchrohr). Es ist wichtig, dass Rauchmelder der offenen Bauart genügend Platz haben, so dass es keine Reflexionen von Licht gibt, das von Wänden abgestrahlt wird (wie in einem Rohr). Dann werden die Detektoren an einen Kommunikationsbus angeschlossen (z.B. eine CAN-Schnittstelle; jede Vorrichtung kann aber auch über einen USB-Bus direkt an einen PC angeschlossen werden, und als Option ist auch eine Ethernet- oder Funkkanalverbindung möglich). Man bringt ein Messinstrument für optische Dichtemessungen in diesen Raum und greift auf seine Daten zu, die auf demselben Computer angezeigt werden. Es wird eine Rauchquelle mit wirklich langsam abbrennendem Material bereitgestellt und der Raum geschlossen. Man erhält konstant Daten über die Rauchdichte von den Detektoren und vom Messinstrument.

It is proposed to perform current regulation in the current stabilizer STC in order to calibrate the sensitivity of the detectors with high precision almost like a fine instrument for optical density measurements. The procedure and procedure for calibration are as follows:

• Place many detectors (15 to 30 at a time) in a fairly large space for calibration (not a smoke tube as usual). It is important that open-type smoke detectors have enough space so that there are no reflections of light emitted from walls (such as in a pipe). Then the detectors are connected to a communication bus (eg a CAN interface, but any device can also be connected directly to a PC via a USB bus, and an Ethernet or radio channel connection is also possible as an option). You bring an optical density meter into this room and access its data displayed on the same computer. It provides a source of smoke with really slow burning material and closes the room. Constant data on the smoke density is obtained from the detectors and the measuring instrument.

When the smoke density on the gauge reaches a lower threshold (e.g., 0.05 db per 1 meter), the system is instructed to transmit that data to the detectors, and these then store that data along with their respective measured density value. At one command, all detectors set their current in the STC current regulator via the DAC2 in the digital unit (drawing 3) so that their reading is equal to the value received from the PC. Since the smoke density increases very slowly, you can get as many points as you like, creating a whole calibration table in the memory of the detectors. When the smoke density reaches its high level (e.g., 0.2 dB per 1 meter), calibration is terminated because it is assumed that the detectors will no longer analyze the situation beyond this point. Thus one first obtains a coarse offset value for all the currents in the light-emitting elements and an entire table of correction coefficients for many points. It is important that you first make a rough correction and then find out about fine-tuning points; This allows for good calibration results.

When the source of smoke ceases to burn, open the venting channel and turn on a fan. Experience teaches that the smoke density in this case becomes even more uniform, more gradual, and uniform with equal distribution over the entire volume. One again records data from the measuring instrument, compares it with the data of already calibrated detectors and, if necessary, makes small adjustments.

Another important point is that the level of current flowing through the LEDs can vary significantly with temperature. Actually, light-emitting diodes have very good stability and a temperature-induced change in their light intensity can be disregarded. But analog components in the current control circuit can change their characteristics. For example, using a FED to open the flow of current through light emitting elements, its response to a particular level from the DAC2 may change sufficiently due to temperature, even if the DAC2 is at the same level of power (but its level is also high) Temperature will change). That is why data obtained under normal conditions should be checked and updated for the entire temperature range. This can be done in a temperature chamber using only 2 smoke densities (or even without smoke). In practice, the detectors may be placed in a temperature chamber (without smoke) and the data on the current in the STC from the ADC compared to data transferred to the DAC2 to achieve that current in the STC. Make corrections to the DAC2 data so that it is the same current measured by the ADC over a wide temperature range (from -50 ° C to + 55 ° C); Points for higher temperatures are calculated by approximation. Results for some real smoke densities can also be demonstrated for this temperature range, but they are quite similar if correction is taken into account in smoke-free conditions.

With this approach, you get a very thoroughly calibrated smoke detector with temperature compensation that accurately measures a smoke density just like a very expensive instrumental device. What is good and new is that no other smoke detectors of the open type on the market can measure the smoke density in concrete numbers, they all give only alarm levels. Most open-type detectors only gain an approximate knowledge of the smoke density in an uncertain volume.

In Fig. 1 it can be seen that a digital thermometer unit TU is contained in the device. First and foremost it is for calibration and temperature compensation thought during their use. However, they can also be used as temperature detectors of the maximum / differential type for better fire detection.

First, let's take a look at the detailed functional scheme in Fig. 3 thrown. It should be together with Fig. 4 to be viewed as.

First shows Fig. 4 a group EE1 of light-emitting elements arranged on a hyperbola. There are deliberately used at least 3 light-emitting diodes, which are located at some distance from each other. This results in a better spatial distribution of the light emitted in space in the detection area from slightly different angles. When light reaches a smoke particle, it is more likely that the light will fall on a flat reflective surface of a smoke particle. Using only one light-emitting diode, the light passes from it at angles of ± 5 ° to the detection area, but each smoke particle in the area receives light only from one direction, the line connecting that particle and the emitting diode. Using 3 diodes, each particle receives light from 3 slightly different directions. This gives a higher probability that light will strike a reflective edge of the smoke particle. Of course, there may also be more than 3 light emitting diodes, and the sensitivity of our device will increase in proportion to the number of light emitting elements. For example, in highly sensitive applications, using a fiber optic cable to transmit light to a high temperature zone and receive signals using the fiber optic cable is very helpful.

It is important to use conventional LEDs rather than laser diodes in general-purpose applications to ensure eye protection. Since light is emitted into the open space, it can reach a person's eyes, and this is particularly dangerous with laser diodes, eg when a child is staring at the detector in operation. For this reason, the proposed smoke detector combines light from several universal diodes only in a very narrow area, about 20 cm from the ceiling. Outside this zone, the light from the three diodes splits into three different beams, loses energy rapidly as distance increases, and is not dangerous to the eyes.

The light emitting diodes EE1 of group 1 in Fig. 4 are on a hyperbola. This is because the light from all diodes should be directed onto the optical axis of the sensor element SE1 at the same angle. The standard recommended angle is 110 °. Thus, if one inserts a tip of an imaginary cone (at an angle of 110 ° from the axis to the side) into the detection range and points to SE1 with its axis, one will see that the points of intersection of this cone with the planar surface of the detector are hyperbola result ( Fig. 5 ). If, in another partial modification of the device (see Fig. 8 ) chooses a sufficiently smaller angle, eg 70 °, then the intersections will give a helical line.

It should be noted that the light emitting elements may be a composite (not just diodes), i. one can use diodes together with a lens or optical prism or other optics. In some applications, one uses an optical fiber, in other applications a special plastic prism that makes the surface of the emissive element flat and level with the surface of the detector. In simple applications, the emitting element is just a diode with its own lens inserted into a narrow channel in the housing (the same solutions apply to the sensor elements). The sensor elements of group SE1 may also be arranged (as a group) on a curve. This can help to avoid obstacles such as flying insects or flies sitting on the diodes. However, the basic version has only one photodiode SE1.

In the block of light-emitting elements in the functional diagram in Fig. 3 if a light-emitting element TEE has been included for test purposes (see Fig. 4 ). The light emitting element for test purposes is necessary because if there is no smoke in the detection area, you get no response and no optical signal back. That's why the photodiode is being tested to see if it works properly and just can not be detected in the area. This diode TEE is only used to prove that the photodiode is active in the sensor element SE1. The light-emitting element for test purposes can be arranged not only on the surface of the detector but also in it, in which case light is transmitted to the rear part of the sensor element SE1. There is no need for the light emitting elements to test emitted light because one can measure the current flowing through these diodes, and where there is power there is also light.

Furthermore one recognizes in Fig. 4 Sensor elements SE1 and SE2. The main sensor element is SE1, it receives light from the detection area and we make measurements based on signals from SE1. The sensor element SE2 is directed away from the detection area, it does not receive signals from the light-emitting elements EE1. Its optical axis is in one and the same direction but at a certain distance from each other (see Fig. 6 ) substantially the same angle with the surface of the detector as the optical axis of SE1. The task of the sensor element SE2 is to protect the device from sunlight and artificial light. When sunlight falls on the detector, both SE1 and SE2 receive this signal because sunlight is always a parallel beam of light.

In the functional schema ( Fig. 3 ), it is seen that signals from the light detecting elements SE1 and SE2 pass through separating capacitors SC1 and SC2 and then go to a summer S1. The isolation capacitors are designed to eliminate a constant offset of CVC1 and CVC2 converters, as well as to eliminate constant background light. Here, a large part of the sun's energy is already excluded. Then in the summer S1 signals from SE1 and SE2 subtracted because the SE2 is inverted at the input of the summer S1. This solution helps keep the rest Exclude from sunlight and achieve a perfect balance against natural and artificial light sources. This is important because sunlight in practice undergoes modulation from the atmosphere, and simply disconnecting a constant level with a cut-off capacitor does not always provide relief. Even though there is a nearby lamp, there are vibration-modulating light modulations. With the proposed solution this is completely excluded.

In Fig. 3 It can be seen that each light detection element is connected to its own current / voltage converter (CVC1 and CVC2). This is new because photodiodes are used in the short circuit mode, CVC1 keeps the voltage in SE1 close to zero, and SE2 generates a current signal in response to light. Then the CVC1 converts signal current into signal voltage. Because of this solution, the device can never be dazzled by a high intensity signal. Usually, a photodiode saturates when it receives high intensity light and can not work for a long period of time.

The operation of the summer S1 in Fig. 3 is managed by the microprocessor. A signal from the summer S1 goes to the amplifier A1, then to the ACD and finally to the microprocessor MP in digital form. This solution helps to balance dust and achieve absolute immunity to all types of artificial light sources, be it incandescent, Hg, halogen or new energy-saving bulbs or even power diode light solutions.

• Der Mikroprozessor MP schaltet im Summierglied S1 beide Kanäle (vom SE1 und SE2) ein und erhält dann verstärkte und digitalisierte Signale, die für den Unterschied zwischen SE1 und SE2 stehen. Handelt es sich um eine schwache Quelle künstlichen Lichts oder befindet sich diese Quelle in einem erheblichen Abstand, werden die Signale vom SE1 und SE2 gleich sein und der MP erhält ein Signal nahe Null. Dann ist es sicher, Messungen durchzuführen.

The method of suppressing interference from artificial light sources includes:

• The microprocessor MP turns on both channels (from SE1 and SE2) in summer S1 and then receives amplified and digitized signals representing the difference between SE1 and SE2. Is it a weak one? Source of artificial light, or if this source is at a significant distance, the signals from SE1 and SE2 will be equal and the MP will receive a signal near zero. Then it is safe to take measurements.

However, if the source of artificial light is strong or so inconvenient that direct light on the SE1 but almost no light falls on the SE2 (for example due to a lampshade or sunroof or any other edge of equipment), sufficient signals will be output at the amplifier A1 abut. The microprocessor MP observes this situation, recognizes the waves of modulated light from artificial sources, because all the lamps get their power at the industrial frequency of 50 Hz or 60 Hz. With emitted light, this frequency is doubled to 100 Hz and 120 Hz, respectively, because the lamps emit light in both positive and negative half cycles. The microprocessor MP finds the time interval in which the signal from the lamps reaches its minimum value, and in this minimum, real measurements of the smoke density are made. This method even eliminates such a dangerous source as a Hg 500W searchlight at a distance of 0.5 m. This particular lamp is very critical because it has a broad spectral characteristic and passes through all the optical filters.

• Der Mikroprozessor MP erhält eine Betriebsspannung aus dem Spannungskonstanthalter STV1 und beginnt mit der Arbeit. Der Mikroprozessor MP schickt eine Messungsanforderung an den ADC und erhält Daten über die Spannungspegel der Speicherkondensatoren im STV1 und der Stromspeicherschaltung PAC zurück. Wenn alle Kondensatoren voll geladen sind, ist der Betrieb der analogen Einheit AU möglich. Danach erfüllt der Mikroprozessor MP konstant die Stromversorgungsverwaltung, wie zuvor beschrieben wurde. Gleichzeitig misst der Mikroprozessor MP konstant die Umgebungstemperatur mit Hilfe der digitalen Thermometereinheit TU. Der Mikroprozessor MP schaltet das Schaltelement KE ein und wartet einen vorbestimmten Zeitraum lang, bis die analoge Einheit AU in einen stabilen Betrieb gelangt. Der Mikroprozessor MP schaltet beide Kanäle im Summierglied S1 ein und empfängt über den ADC ein Signal vom Verstärker A1, um den Zeitpunkt zur richtigen Messung mit minimalem optischen Rauschen zu bestimmen, wie oben im Verfahren zur Bekämpfung künstlicher Lichtquellen beschrieben wurde.

The main method of measuring smoke density involves the following steps:

• The microprocessor MP receives an operating voltage from the voltage stabilizer STV1 and starts work. The microprocessor MP sends a measurement request to the ADC and retrieves data about the voltage levels of the storage capacitors in the STV1 and the current storage circuit PAC. When all capacitors are fully charged, the operation of the AU analog unit is possible. Thereafter, the microprocessor MP constantly performs the power management as described above. At the same time, the microprocessor MP constantly measures the ambient temperature with the aid of the digital thermometer unit TU. The microprocessor MP turns on the switching element KE and waits for a predetermined period of time until the analog Unit AU comes into stable operation. Microprocessor MP turns on both channels in summer S1 and receives a signal from amplifier A1 via the ADC to determine the timing for proper measurement with minimal optical noise, as described above in the Artificial Light Source Control method.

When the signal from the amplifier A1 reaches its minimum, the microprocessor MP turns on a freshly charged storage capacitor C2 in the voltage stabilizer STV1 (and turns off the C1 of the AU, thereby connecting the C1 to the input voltage). In simpler modifications, the microprocessor MP simply monitors only the voltage on the STV1, so that the analog unit AU gets the necessary voltage, and if the stabilized voltage on the analog unit AU differs from a predetermined value, the microprocessor MP calculates this difference and decreases Corrections to received signals. When the microprocessor MP has determined the correct time for measurements, it sends data about the level of current to the DAC2 which should be established across the light-emitting elements with respect to the ambient temperature. The digital / analog converter DAC2 sets its output according to this data, and this signal goes to the current stabilizer STC. Then, the microprocessor MP turns on the current stabilizer STC and sends measurement current to the light-emitting elements (group EE1 in FIG Fig. 4 ). Light from the light-emitting elements runs at the same angle to the optical axis of the main sensor element SE1 (FIG. Figure 5 ) through the detection area. Preferably, but not exclusively, the angle is 110 °.

First, consider a situation where there is no smoke in the area. Depending on the signal generated by the STC, the light emitting elements (Group 1) send a very short pulse of light (or series of pulses) of known duration and intensity characteristic under the control of the microprocessor MP. The light signal reaches the detection area, but there is no smoke and so no light can be scattered by smoke particles. However, obstacles may be in the area, such as nearby walls or rows of containers in warehouses and the like. Like., Or also hands of cleaning staff near the detector and on this sitting insect. Thus, even without smoke, a certain signal from the light-emitting elements can be reflected back from the detection area, and this light reaches the sensor element SE1. Then this light is converted by the SE1 into an electrical current signal, which then converts the current / voltage converter CVC1 into a voltage signal. Then only the AC part of this signal passes through the isolating capacitor SC1. The same conversion is done by the SE2, the CVC2 and the SC2. Both channels meet in Summierglied S1 each other.

If backlight sources are present, the light signal from this reaches both sensor elements SE1 and SE2 and is effectively subtracted in the summer S1. Then only high frequency pulses (above 1 kHz) will pass through the SC3 isolating capacitor to protect the measuring part from industrial EMI radiation (at frequencies of about 50-60 Hz or 100-120 Hz). Short duration pulses from the light emitting elements reflected from obstacles in the area then pass through the separator capacitor SC3 and reach the summer S2. The microprocessor MP sends a zero value to the DAC1 so that the signal from the SC3 goes to the output of the summer S2 unchanged. The microprocessor MP sends a command to the ADC to take measurements and receives back data via signals at the output of the summer S2. If there is a very strong reflection (for example, of nearby walls or if one protects a ventilation duct or a narrow channel for electric cables), then the microprocessor already receives a significant signal at this stage. Thus, the microprocessor MP sends a calculated value to the DAC1, and the DAC1 equalizes the noise measured from reflections in the detection area.

Then a new measurement takes place, this time the microprocessor MP sets the level in the DAC1 in advance to the previously calculated value, so that the signal from the DAC1 is subtracted from the signal from the separating capacitor SC3. Since the signals are almost completely balanced, you now need a gain, to see a certain significant signal. This is the reason why the MP microprocessor MP also receives signals from the output of amplifiers A2, A3 and A4, each of which has a certain gain, preferably with steps of x10 (each signal being amplified by 10) at each amplifier , Thereafter, this microprocessor MP will correct data for the DAC1 and will continue to use that more accurate value. The most accurate measurement of a noise signal from reflection occurs when the DAC1 has no smaller numbers to perform a fine correction and almost all of the noise is balanced. Then the microprocessor MP uses the ADC to measure a signal from an integrator Int which integrates the signal from the A4 during pulses. The result provides an offset value for fine correction, and this data is stored in the MP along with correction data for the DAC1 (eg, in a ROM or flash memory). The microprocessor MP continues to perform measurements at certain intervals, for example, 1 time in 1 second.

When smoke appears in the detection area, light from the light-emitting elements in the detection area strikes smoke particles, some light is reflected to the sensor element DE1, and no light is reflected by smoke particles to the sensor element SE2 ( Fig. 6 ). The microprocessor MP determines the duration of short pulses of light (or bursts of pulses) in terms of temperature so that the pulses match the operating frequency of narrow band filters in the amplifiers A2, A3 and A4 (as described in the calibration procedure above). Usually, this duration will be on the order of 15 microseconds under normal conditions. The microprocessor MP also determines the light intensity, sends data to the DAC2, and produces the known current in the current stabilizer STC (the data sent to the DAC2 depends on the temperature value, as described above).

The microprocessor MP controls the real current through the light-emitting elements by means of the ADC. When a light signal from the detection area is scattered by smoke particles, it reaches the sensor element SE1 and becomes there converted into an electrical current signal. Then the current / voltage converter CVC1 converts it into a voltage signal. Only the AC voltage part of this signal passes through the isolating capacitor SC1. The same conversion is done by the SE2, the CVC2, SC2 only on the noise signal.

A light signal from backlight sources reaches both sensor elements SE1 and SE2 and is subtracted in summer S1. Short-duration pulses from the light-emitting elements pass through the separating capacitor SC3 and reach the summing S2. The microprocessor MP sends a previously calculated value for correcting a noise signal from reflections to the DAC1. In summer S2, the signals are subtracted, and then only the true part of this signal, which corresponds to the real signal of smoke, goes to amplifiers A2, A3 A4 and integrator Int. The microprocessor MP layers a measurement request to the ADC and receives all of these signals in digital form. Then the microprocessor MP considers the measurement signal level, subtracts the offset value from the noise, compares the result to the coefficient table stored in its memory (according to factory calibration section 3), and calculates the real smoke density value. Then, the MP compares this value with predetermined thresholds, and if the measurement is greater than a first threshold, the MP generates a "attention" signal. If this value has risen to a second threshold during a predetermined time (as recommended by regulations), the MP will generate a "Alarm" signal.

There may also be other fire protection policies, for example, a user may choose to only cross a threshold without time calculation. Or the user may determine that the smoke intensity is differentiated and an alarm is given in case of a sudden signal increase. Or the user may choose to ignore sudden jumps (because of the proximity of the person moving the detector), but in this case the detector can take a series of quick successive measurements, thereby taking into account reflections from moving objects eliminate. For other applications, a quick response even to low smoke levels is essential (for example, ventilation systems extract almost the entire volume of air and fill rooms with fresh air for 1 minute).

The microprocessor MP can transmit with the help of an output driver always accurate data on the smoke density to the higher level of the fire protection system. And this is also highly recommended because at the higher level, the receiving unit collects information about smoke density levels from many different detectors and performs statistical analysis, separating numbers that may give rise to suspicion (for example, if there is real smoke near a detector) small source such as a cigarette is detected, but at other detectors only a slow increase in the background noise level can be seen). This is accomplished in one of our many detector unit modifications. That's almost all about the main process.

The procedure for dust compensation in the detector includes special design solutions that are available in Fig. 7 are shown. The inventors have found that when a groove is made on the circumference of the detector housing to pass through the light emitting elements and sensor elements, reflections of light passing through the reflective edges of the groove from the light emitting elements to the sensor elements are seen even if there is no direct passage of light. It does not matter how big or thin this groove is, it should only pass through the elements with the light emitting and sensing elements located on its inside. So there are several design solutions for dust compensation.

In a first solution, you milled a broad oval plane and leave a smooth edge on the circumference in the form of a helix, and in the middle of the housing in the form of a flat circle. In the second construction solution, there are two separate grooves of oval shape, one containing light emitting elements and the main sensing element SE1, and the second, smaller oval groove containing light emitting Element and the second sensor element SE2. A third design solution has only small reflective surfaces near the light-emitting elements and the second sensor element. The small reflective edges in this solution are actually just a continuation of channels in the detector housing into which light-emitting elements are inserted; this is sufficient to obtain a sufficient reflection to the sensor element SE1. All protruding parts are in Fig. 7 marked hatched.

In the proposed method of dust compensation, the microprocessor MP first measures the signal from the main sensor element SE1. For this purpose, the microprocessor MP selects a possible time for measurement according to the method for combating artificial light, then measures the signal from the detection area after the main process, and then corrects it. A dust correction is only carried out if there is no risk of fire. Then, the MP transmits a signal to the summer S1 and turns off the channel from the sensor element SE2 to perform only measurements on SE1. The MP measures the signal from the SE1 and stores it in its memory, then sends a signal to the summer S1 and turns on the channel from the sensor element SE1 and from the sensor element SE2 to take measurements only on the SE2. Then the MP measures the signal from the SE2 and also stores it in its memory. The MP compares signals from an earlier calibration with newly measured signals and calculates a saturation of the signal due to dust on its surface.

Thanks to this process, you know exactly what numbers the detector was measuring when it was first installed and what numbers it has after years of operation. Also, signals are accurately measured at the working diodes SE1 and SE2 with real light emitting elements used for measurements in the main process. This prevents errors due to different dust thicknesses or obstacles on diodes. It is also important to note that in this case no test light emitting element is needed because one always has a signal from the reflective groove to test the device.

In various figures, there are various design variants: Smoke detectors of the open design (variant 1, Fig. 4 ), Smoke detectors of the open design combined with temperature detector (maximum / differential design) (variant 2, Fig. 13 ), Smoke detectors of open design, combined with UV flame detector (variant 3, Fig. 14 ), Smoke detector of open design, combined with IR flame detector (sensitive in at least 2 spectral ranges) (variant 4, Fig. 14 ), Smoke detector of open design, combined with temperature detector and UV flame detector (variant 5, Fig. 15 ), Smoke detector of open design, combined with temperature detector and IR flame detector (variant 6, Fig. 15 ). Smoke detector of open design, combined with temperature detector, UV flame detector and IR flame detector (sensitive in at least two spectral ranges) (variant 7, Fig. 16 ).

There may also be partial modifications combined with temperature detectors and flame detectors of the UV and / or IR type. All of these variants may be equipped with optical fibers or cables to establish communication between the MU control unit (where all the electronics are located) and a remote RDU detector unit (where only optics are to be used for high temperature applications or reliable, simple electronics such as diodes) (variant 10) . Fig. 17 ). A modified solution is variant 11 in Fig. 18 shown. Fig. 18 shows a main detector unit MU, which is connected to a plurality of remote sensor units RDU1 to RDU4. This is a good solution for the industry, where a large work hall or workshop can be protected as a zone for a fire extinguishing system. This gives users the opportunity to install only one or two detectors with many remote sensor units (up to 30 on a main unit) instead of dozens of separate detectors. This is an exceptionally economical solution.

• Aus Fig. 3 ist ersichtlich, dass der Mikroprozessor MP Feineinstellungen in den Verstärkern A2, A3 und A4 durchführen kann; dies wird zur automatischen Kalibrierung der Vorrichtung im Werk benötigt. Die Verbindung zwischen dem MP und dem Integrierglied ist dazu gedacht, das Integrierglied nur in bekannten Zeiträumen mit Speicherung des Pegels des integrierten Signals und seiner Rücksetzung durch den MP arbeiten zu lassen. Es wird gegenwärtig ein Hochgeschwindigkeits-ADC verwendet, in preisgünstigeren Modifizierungen kann man aber einen langsameren ADC in Kombination mit einem durch den Mikroprozessor MP gesteuerten Spitzendetektor verwenden. Der ADC kann ein Teil des Mikroprozessors sein.

In the following some mentionable aspects of advantageous embodiments of the proposed smoke detector or its operation and its application are mentioned:

• Out Fig. 3 it can be seen that the microprocessor MP can perform fine adjustments in the amplifiers A2, A3 and A4; this is needed to automatically calibrate the device in the factory. The connection between the MP and the integrator is intended to allow the integrator to operate only during known periods of storage of the level of the integrated signal and its reset by the MP. A high speed ADC is currently used, but in more cost effective modifications one can use a slower ADC in combination with a peak detector controlled by the microprocessor MP. The ADC can be part of the microprocessor.

The typically weak signal of the light sensing element generally requires high gain factors, but these are inevitably associated with corresponding power consumption and additional noise. In an embodiment of the evaluation circuit, therefore, a primary signal consisting of a positive and subsequent negative half-wave, after filtering and amplification, is processed by inverting the negative half-wave and adding to the positive half-wave. In an embodiment in which suitable switching elements are provided in front of the integrator, parts of the half-waves are masked out in order in particular to pass only the middle section with the greatest signal amplitude as the useful signal.

Practical designs have a metal body, are shockproof and vandal resistant, have a socket with screws, no flush solution, but a solid attachment of wires to contacts on the side surface of the socket with screws. This solution is resistant to all types of vibration and can be safely used even in railway wagons.

There may be several groups of light-emitting elements, which gives a better performance in black smoke (see. Fig. 8 . 9 . 10 ). Two different zones can be set up for earlier detection, and for smoke spreading in layers or horizons (cf. Fig. 11 ). There may be groups of light emitting elements with different spectral sensitivity, this allows us to distinguish black smoke and aerosols from burning metals (such as Na, Al, Fe) (see. Fig. 12 ). The open-type smoke detector can be combined with a temperature detector, flame, UV and IR detector (cf. Fig. 13 . 14 . 15 . 16 ).

One aspect of the present invention is also in the oppose of constructing a novel smoke detection system as disclosed in US Pat Fig. 19 is shown sketchy. The smoke detection system SYS comprises in the exemplary representation of a system control station SCS and three smoke detectors SD1, SD2 and SD3 with fundamentally different structure, which are arranged in different rooms of a building to be monitored. The smoke detector SD1 is of the integrated type, with all components housed in a single housing; the smoke detector RD2 is of the two-part type, as in Fig. 17 and 19 and comprises a control unit MU2 and a remote detector unit RDU2 and the smoke detector RD3 can be referred to as a multi-part type, in which in addition to a control unit MU3 and a detector unit RDU3 containing the actual smoke message serving ( at least) a remote additional detector XDU is provided. Connections between the system components and subcomponents are made in the manner described in the general part of the description as a first, second, and third level bidirectional communication link, at least in part, on an optical fiber basis.

One method of operating such a network is as follows: There is a special program on a laptop or receiver unit with radio channel, and this program finds a detector from our company as soon as it is turned on. Then the detectors are switched on one at a time and attached to the ceiling according to the project documentation, and no wire connection is needed. The detectors register themselves in the PC, and they get access rights depending on their priority. So you first install "server" messages that forward information from other subordinate detectors to the PC, and the "server" messages must always be in direct view of each other. If a "server" detector is separated from others by a wall, it may be necessary to make a short wire connection through the wall to the nearest detector manufacture. In practice, these wire connections are very short (about 2 m) and can be mounted through the door entrance. Subordinate detectors in each room transmit their information to the "server" detectors, which then pass them through each other to the main PC or just a receiver unit with radio channel. This means that a detector network can be set up in a school without difficulty, without wire connections and costs for its assembly and with considerable savings in hardware.

The embodiment of the invention is not limited to the examples shown and described herein and the aspects highlighted, but also in a variety of modifications are possible, which are within the scope of technical action.

Claims (16)

1. Open-type smoke detector comprising at least one pulse-operated light emitting element and at least one light detecting element in an open housing, and a power supply unit coupled with said light emitting element or elements, wherein the power supply unit comprises voltage stabilizing means and an energy collecting device and a digital operation monitoring and controlling unit for monitoring and controlling the operation of the power supply unit and thus the light emitting element or elements, wherein the digital operation monitoring and controlling unit is configured for real-time controlling a switch-on time and pulse duration of the light emitting element or elements as a function of a temperature signal.
2. Smoke detector according to claim 1, having at least one built-in temperature sensor coupled with a T-sensor input of the digital operation monitoring and controlling unit.
3. Smoke detector according to claim 1 or 2, wherein the power supply unit comprises current stabilizing means arranged at the output side of the energy collecting device and coupled with the operation monitoring and controlling unit via a control line so as to be controlled by the operation monitoring and controlling unit.
4. Smoke detector according to any one of the preceding claims, wherein the power supply unit is configured for supplying the light emitting element or elements with sine pulses.
5. Smoke detector according to any one of the preceding claims, wherein the operation monitoring and controlling unit comprises interference signal monitoring means for optically monitoring the detection area and is configured for applying supply pulses to the light emitting element or elements in periods in which external optical noise has a value below an average value determined over a predetermined period.
6. Smoke detector according to claim 5, wherein the operation monitoring and controlling unit is configured for storing, as a background interference signal, an optical signal detected over a predetermined monitoring period in the absence of a smoke detection signal, which optical signal contains e.g. reflection signals from the smoke detector's constructional environment, and for utilizing it in compensation controlling the operation of the light emitting element or elements.
7. Smoke detector according to claim 6, wherein, for compensation controlling the light emitting element or elements, the operation monitoring and controlling unit operates at the same pulse shapes as are provided for the operation thereof without compensation control.
8. Smoke detector according to any one of the preceding claims, wherein the light emitting element or elements are configured for supplying an emission signal in at least two different spectral ranges, and the light detecting element or light detecting elements are adapted to detect signals in all of the spectral ranges of emission used.
9. Smoke detector according to any one of the preceding claims, comprising a built-in flame detector coupled with a flame detector input of the operation monitoring and controlling unit, and wherein the operation monitoring and controlling unit is configured for controlling detector operation in response to a signal from the flame detector.
10. Smoke detector according to claim 9, wherein the flame detector comprises a UV-type and/or IR-type detector.
11. Smoke detector according to any one of the preceding claims, comprising three or more LEDs arranged in a common plane on a hyperbolic or spiral curve facing the light emitting element or elements.
12. Smoke detector according to any one of the preceding claims, including a test light emitting element provided and configured solely for an operation for test purposes.
13. Smoke detector according to any one of the preceding claims, including a calibrating light detecting element provided and configured solely for an operation by means of which signals of the light detecting element or light detecting elements are calibrated.
14. Smoke detector according to claim 13, wherein the open housing comprises at least one light reflecting surface configured for shaping the optical path between the light emitting element and the light detecting element so as to effect a dust correction of the detector signals.
15. Smoke detector according to any one of the preceding claims, wherein light emitting elements are provided in the direct detection area of light detecting elements on the same optical axis, and a first pair of a first light emitting element and a first light detecting element is enclosed in a hermetically tight housing, and a second pair of a second light emitting element and a second light detecting element is disposed within the open housing, and an evaluation unit is configured for receiving the signals from the pair of first and second elements and for processing the signals from the first pair for interference-compensating the signals from the second pair of elements.
16. Smoke detector according to any one of the preceding claims, comprising at least one sensor input, e.g. a multimode optical fiber input, for coupling the smoke detector with an external sensor element, e.g. an external temperature sensor and/or external flame detector.

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