EP2407949B1 - Ring shaped auxiliary light source - Google Patents

Abstract

The detector (1) has a measuring light transmitter (4) provided in a measuring chamber (3) for transmitting light into the chamber. A diffused light test receiver (5) receives the light emitted by the transmitter. A diffused light measuring volume (19) is provided in the chamber with a labyrinth. A detector housing and the chamber are partially manufactured from a material with shiftable optical characteristics. The shiftable material that fulfills function of shiftable panel is not arranged between the transmitter or the receiver and the measuring volume. Independent claims are also included for the following: (1) a method for manufacturing a smoke detector (2) a method for detecting contamination of a smoke inlet opening and/or insect grid of a detector (3) a method for coloring a detector.

Description

The present invention relates to a fire detector with a unit for detecting soiling of smoke inlet openings.

Fire and smoke alarms warn of dangers such as fire and smoke and must therefore be ready for use at all times. To ensure that the necessary readiness is always ensured, the detectors must be regularly checked and serviced. A large part of the necessary functional tests, such as the testing of the sensors, the detectors can perform themselves in the context of conventional self-tests. The results of these self-tests can then be documented in the detector or in a central office. If an error is detected in such a self-test, this is indicated with display means as a fault of the detector. Depending on the configuration of the existing installation, this fault can either be displayed only at the detector, at a control panel or at other terminals. In addition, it is conceivable that service personnel will be informed directly about a communication medium via the fault. As part of a performance check to be carried out at least once a year For example, DIN 14676 for smoke detectors requires, among other things, a visual inspection. In this visual inspection soiling of the smoke inlet openings should be detected. Since, in particular, when the regular checks are to be carried out by service personnel, high costs are incurred due to the necessary inspections of properties, solutions are sought by which the detection of soiling of smoke inlets can be carried out automatically by the detector itself.

So is for example from the EP 0 503 167 B1 a scattered light smoke detector is known, which detects the pollution of an insect screen. The insect screen protects the measuring chamber of a smoke detector against the ingress of insects, which could otherwise trigger false alarms, but lets smoke pass, which can then be detected in the measuring chamber. In this solution, an auxiliary light transmitter is mounted inside or outside the detector. The light from the auxiliary light transmitter penetrates the insect screen and then enters the measuring chamber of the smoke detector. There it can be measured by the receiver, who otherwise only detects the light scattered by smoke. By comparing the current light intensity with the original one, the level of contamination of the detector can be used. The disadvantage of the light of the auxiliary light source, after it has passed the insect screen, still penetrate through a labyrinth, which has just the task of preventing light from outside the measuring chamber from entering the measuring chamber. The labyrinth thus also prevents the auxiliary light from entering the measuring chamber and thus reduces the measuring effect.

Another device for detecting contamination of the insect screen of a scattered light fire detector is in the JP 02227800 shown. Just like in the EP 0 503 167 B1 Here is an auxiliary light source outside the insect screen attached. Here, this is so appropriate that the light emitted by it is directed directly in the direction of the measuring light receiver in the measuring chamber. However, in order to prevent the auxiliary light from being hindered by the measurement chamber labyrinth at the receiver, a labyrinth element that would lie between the auxiliary light transmitter and the measurement receiver is omitted and replaced by an external labyrinth element mounted outside the insect screen behind the auxiliary light transmitter. With this device, the pollution of the insect screen can be monitored only at a single point, which is also protected by the external labyrinth element against the rest of the grid from contamination. Therefore, the contamination measurement at this point does not allow in most cases a reliable statement about the pollution of the rest of the grid.

In addition, from the DE 101 10 231 A1 a scattered light smoke detector with a switchable optical aperture between the scattered light measuring receiver and the measuring volume known. The aperture serves to switch between two different measurement volumes in two different spatial areas.

The invention is therefore an object of the invention to provide a smoke detector of the type mentioned above, which eliminates the disadvantages of the prior art mentioned or at least improved and moreover offers further advantages.

The object is achieved according to the features of claim 1

A fire alarm according to the invention comprises a unit for detecting soiling of the smoke inlet openings, comprising at least one auxiliary light source which is mounted outside the detector and a light guide which is arranged in a ring inside the detector and collects incident light from outside and directs it to a receiver inside the detector.

The auxiliary light source is guided around the housing as an annular light guide.

Fig. 1

einen Schnitt durch einen ersten erfindungsgemäßen Rauchmelder mit schaltbaren Fenstern im Gehäuse und der Messkammer;

Fig. 2

einen zweiten, demjenigen in Fig.1 ähnlichen Melder, der jedoch mit einem zusätzlich Licht sammelnden Lichtleiter auf der Innenseite des Insektengitters versehn ist;

Fig. 3

einen Schnitt durch eine Messkammer mit einem schaltbaren Labyrinthelement;

Fig. 4

einen Schnitt durch einen Melder mit mehreren schaltbaren Labyrinthelementen und Hilfslichtquellen;

Fig. 5

einen Rauchmelder mit einer ringförmigen Hilfslichtquelle und einem ringförmigen Lichtsammler.

The invention is explained below with reference to embodiments in the drawing. The invention corresponds to the embodiments of Figures 2 and 5 , The other embodiments describe variants that are not part of the invention. It shows in partially highly schematic representation of the

Fig. 1

a section through a first smoke detector according to the invention with switchable windows in the housing and the measuring chamber;

Fig. 2

a second, the one in Fig.1 similar detector, but which is versaun with an additional light collecting optical fiber on the inside of the insect screen;

Fig. 3

a section through a measuring chamber with a switchable labyrinth element;

Fig. 4

a section through a detector with several switchable labyrinth elements and auxiliary light sources;

Fig. 5

a smoke detector with an annular auxiliary light source and an annular light collector.

The Fig. 1 shows in greatly simplified form a scattered light smoke detector (1) with a housing (2) and a measuring chamber (3). In the measuring chamber (3) there is a measuring light transmitter (4) which emits light into the measuring chamber (3) and a scattered light measuring receiver (5) which receives light emitted by the measuring light transmitter (4) and smoke in a scattered light measuring volume (19) or other aerosols was scattered. Above the scattered light measuring receiver (5) is located in the measuring chamber (3) or the measuring chamber housing (3) a first window (6) Above the first window (6) in the housing (2) of the detector (1) has a second window (7 ) appropriate. Between the first and second windows (6/7) a lens (8) is inserted here. The lens (8) can also be part of the first and / or second window (6/7). According to the invention, at least one of the windows (6/7) is made of electrochromic material, such as transparent electrodes and tungsten oxide coated glass or transparent plastic. Via a line, not shown, a voltage to the first and / or second window (6/7) can be created. As a result, they become transparent or at least translucent and light can penetrate through both windows (6/7) into the measuring chamber (3) and be detected by the scattered light measuring receiver (5). This allows the scattered light measuring receiver (5) to perform other tasks and be used for example as a communication receiver, flame sensor or brightness sensor. The signals supplied by the scattered light measuring receiver (5) are then, as in the scattered light measurement, evaluated in a known manner by an evaluation circuit, not shown. In the evaluation circuit Depending on the measurement task, the signals are examined for intensity, flicker frequency or modulated information. If the scattered light measuring receiver (5) is used as a flame sensor, it makes sense to install the lens (8) as a fisheye lens directly into the second window (7) so that the largest possible area can be monitored. It is within the meaning of the invention that the lens (8) is made of electrochromatic material.

By re-applying a voltage of opposite polarity to the first and / or the second window (6/7), the electrochromic material again becomes opaque. As a result, the measuring chamber (3) again protected against the ingress of extraneous light and a scattered light smoke measurement can be carried out in a known manner.

The in Fig. 1 detector shown additionally has an auxiliary light source (9a) which is mounted outside the housing. Light emitted from this auxiliary light source (9a) penetrates through the smoke inlet openings (10) into the housing (2) of the detector (1) and through an insect screen (11). In order for the light emitted by the auxiliary light source (9a) to be detected by the scattered light measuring receiver (5) for detecting contamination of the smoke inlet openings and the insect screen (11), at least one labyrinth element (12) is provided which is made of electrochromatic material. By applying a voltage to the labyrinth element it becomes transparent and the light emitted by the auxiliary light source (9a) can pass through the smoke inlet openings (10) in the housing (2), the insect screen (11) and the labyrinth element (12) onto the scattered light measuring receiver (5). fall and be detected there. In an evaluation circuit, not shown, the degree of attenuation of this light to assess the pollution of smoke inlet openings (10) and insect screens (11) used.

As an alternative to the auxiliary light source (9a) outside the housing (2), an auxiliary light source (9b) can also be mounted directly on the printed circuit board (14) within the housing (2). In order that, nevertheless, the light of this auxiliary light source (9b) can be radiated outside the housing (2), a light guide (13) is provided, which leads the light emitted by the auxiliary light source (9b) to the outside. In this case, the light guide (13) is designed so that the light is emitted through the smoke inlet openings (10) into the interior of the detector (1).

In Fig. 2 is, also very simplified, a detector (1) with another device for detecting contamination of the smoke inlet openings (10) and the insect screen (11) shown. This embodiment has, as well as in Fig. 1 shown, via an auxiliary light source (9b) and a light guide (13) which receives the light emitted from the auxiliary light source light and radiates outside of the detector housing (2) in the direction of the smoke inlet openings. According to the invention, the light guide (13) is as in Fig. 5 can be seen outside the housing (2) annularly guided around the smoke inlet openings (10). On the inside of the insect screen (11) is a second, ring-shaped light guide, the light, which falls through the insect screen (11), collects and on a pollution measuring receiver (15) passes. In an evaluation circuit, not shown, the attenuation of the light emitted by the auxiliary light transmitter (9b) and measured by the pollution measuring receiver (15) light as a measure of the degree of contamination of the smoke inlet openings (10) and the insect screen (11) is evaluated.

The Fig. 3 schematically shows a measuring chamber (3) of a scattered light smoke detector (1) with a measuring light transmitter (4), a scattered light measuring receiver (5), a scattered light measuring volume (19) and a labyrinth (17), which consists of several approximately L-shaped opaque labyrinth elements (18) and a labyrinth element (12), which is switchable in its optical properties and is preferably made of electrochromatic material. Opposite the scattered light measuring receiver (5) outside the measuring chamber (3) an auxiliary light source (9a) is mounted, which is used for the detection of contamination of the insect screen (11) and the smoke inlet openings (10) not shown here.

An in Fig. 4 shown detector (1) differs from that in Fig. 3 shown in that in addition a part of the housing (2) is shown, on which a plurality of auxiliary light sources (9a) are mounted along the circumference. Each of these auxiliary light sources (9a) is assigned a labyrinth element (12) which can be switched in its optical properties. The scattered light measuring receiver (5) is mounted here in the middle of the measuring chamber (3) and can receive light from each of the auxiliary light sources (9a) equally.

In Fig. 5 are opposite to the representation in Fig. 4 the outside auxiliary light sources (9a) are replaced by at least one auxiliary light source (9b) located inside the detector housing (2), the light of which is led out through a first light guide (13) and from the latter through the smoke inlet openings (10) into the interior of the detector (1 ) is blasted. The first light guide (13) surrounds the smoke inlet openings (10) annularly, whereby the polluted state of the smoke inlet openings (10) and the insect screen (11) on the full circumference of the measuring chamber (3) can be measured. On the inside of the insect screen (11), a second light guide (16) is arranged in a ring, which collects light which penetrates into the detector (1) and leads to a contamination measuring receiver (15). In addition, the labyrinth (17) contains a plurality of switchable labyrinth elements (12) which can also be switched individually via separate voltage lines, not shown. As a result, individual smoke inlet openings (10) or segments can be specifically examined for contamination.

In the method for operating the above-described detectors, first of all a first voltage is applied to all parts of electrochromic material (6, 7, 8, 12) of the measuring chamber (3) and the housing (2), which is polarized such that said parts be opaque. In the state thus achieved, the detector (1) behaves like an ordinary scattered light smoke detector with a measuring chamber and a smoke measurement is carried out in a known manner. Subsequently, to the first window (6) and, if the second window (7) and the lens (8) are also made of electrochromic material, also applied to this a second electrical voltage with reverse polarity to the first voltage. As a result, both windows (6, 7) and the lens (8) are transparent and light from an observation area outside the detector (1) can penetrate through the measuring chamber housing (3) into the measuring chamber (3) and fall onto the scattered light measuring receiver (5) , The scattered light measuring receiver (5) converts the light incident on it into electrical signals which are examined by an evaluation circuit. To detect flames, the signal is examined for intensity and flicker frequency, as in known flame detectors. In addition, the intensity of the incident light can also be used to increase the brightness of the interstitial space to eat. The brightness information can now either be used inside the detector to deliver, for example, disturbance messages only from a certain brightness, because it can be expected that in dark rooms either no one is present and the fault message can not be perceived anyway, or people want to sleep, which should not be disturbed unnecessarily. As soon as a certain minimum brightness is detected, the fault messages, for example for a weak battery of a smoke detector, are emitted again. The brightness information could also be passed through an interface to a building management system, which automatically closes shutters, for example, when too much sunlight falls into the room.

Finally, the signals can be examined for contained information such as commands for the detector itself. For example, commands can be sent to the detector via a remote control, which can perform a self-test on the detector (1) or mute a pending alarm.

In the method for measuring the contamination of the smoke inlet openings (10), first all switchable windows (6, 7) and labyrinth elements are switched opaque. Subsequently, a measurement is carried out with the scattered light measuring receiver (5) or a separate, not shown pollution measuring receiver in the measuring chamber with a dark measuring chamber and the measured value is stored as a "dark value". Subsequently, at least one of the labyrinth elements (12) is switched translucent. Thereafter, a measurement is again performed on the scattered light measuring receiver (5) or the separate, not shown pollution measuring receiver. This second measured value is also saved as "Transwert". If, for example, the brightness of the interstitial space is known from a brightness measurement performed previously and described above, the light attenuation caused by the smoke inlet openings (10) and the insect screen (11) can be determined directly from the brightness value and the "transvalue" Dark value for correcting both measured values is subtracted from these. Since a clogged insect screen (11) or even masked smoke inlet openings (10) have a significantly higher attenuation than clean smoke inlet openings (10) and insect screens (11), the value of the light attenuation serves as a measure of the pollution of the smoke inlet openings (10) and the insect screen ( 11). The currently determined damping is compared with a stored initial value. In this case, if the difference between the two values exceeds a predetermined level, a fault message is issued and a fouling flag is set.

If no brightness measurement value is available because this measurement is not provided in the corresponding model variant or the room brightness is insufficient for an attenuation measurement, an auxiliary light source (9a / 9b) is switched on and a third measured value is stored as "auxiliary transmittance". Since the radiation intensity of the auxiliary light source (9a / 9b) can be assumed to be approximately constant, the difference between "auxiliary transmittance" and "transvalue" can serve as a measure for the contamination of the smoke inlet openings (10) and the insect screen (11). If in the detector (1) a circuit for extraneous light suppression is provided, as they are known from the light barrier technology or extinction fire detectors ago or in the dark in the surveillance area can already be used as a measure of pollution, the corrected "Hilfstranswert. In these cases, only the "auxiliary" with a predefined Threshold compared and detected a fault, if this is exceeded.

In a modified method for measuring the contamination of the smoke inlet openings (10), light penetrating into the detector (1) is collected behind the insect screen (11) by an annular light guide (13) and directed to a contamination measuring receiver (15) and measured there. These measured values are also saved as "Transwert". If here too the brightness of the interstitial space is known from a preceding or following brightness measurement described above, the light attenuation and, consequently, the fouling of the smoke inlet openings (10) and the insect screen can be determined from the brightness value and the "transvalue" (11). However, if the brightness value is missing, the contamination of the smoke inlet openings (10) and the insect screen (11) can again be closed with the aid of the auxiliary light source (9a / 9b) as described above.

In an exemplary method for coloring a detector, an initially white housing (2) of a detector (1) is coated with transparent electrodes, between which Prussian blue is applied. Thereafter, a first voltage is applied to the electrodes, which reduces the Prussian blue and thus becomes colorless. Thus, the detector (1) first receives its base color. As soon as a different color is desired, a second voltage is applied with a polarity opposite to the first voltage. This turns the Prussian blue and thus the detector (1) blue. If other color effects are to be realized, then the Prussian blue is replaced by another electrochromic substance such as tungsten oxide.

Claims (1)

1. Fire alarm having a unit for detecting contamination of smoke entry openings (10), comprising at least one auxiliary light source (9a, 9b) arranged outside the alarm (1), characterized in that the auxiliary light source (9a, 9b) is guided, in the form of an annular light guide (13), around the smoke entry openings (10) and emits light into the smoke entry openings (10), and in that the unit comprises a light guide (16) placed in an annular fashion inside the alarm, which light guide (16) collects light that is incident from outside and guides it onto a receiver (15).

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