NO321726B1 - Device for testing the function of strolysro quartz detectors - Google Patents

Abstract

PURPOSE: An apparatus for inspecting a function of dispersed light smoke sense is to be satisfactorily operated for the sense to be inspected in every arranged location and to be easily adjusted to other senses. CONSTITUTION: An apparatus for inspecting a function of dispersed light smoke sense comprises:a measurement chamber(5) equipped with a measurement light receiver(7); and an adaptor(1) having an inspection light source(3) to be synchronously operated as the light pulse of the measurement light source(6) to provide the inspection light pulse for the measurement light receiver(7); and a detector(2) inducted to electromagnetic field generated by the current pulse of measurement light source(6), controlling the inspection light source(3) and formed by induction coil.

Description

The invention relates to a device for testing the function of stray light smoke detectors which is provided with a measuring chamber with a measuring light source that emits light pulses, and a measuring light receiver, with an adapter containing a test light source that is operated synchronously with the measuring light source light pulses, to influence the measuring light receiver with test light pulses.

As is known, the measuring chamber in stray light smoke detectors is shielded as tightly as possible from outside light to make the detector as immune as possible to extraneous light. Even so, this shielding cannot be absolute because the detectors must be open to the outside atmosphere in order for smoke to penetrate into the measuring chamber. In order to minimize the disturbing influence of the extraneous light that reaches the measuring chamber despite the shielding, the detector's evaluation link is designed so that the measuring light receiver only reacts to the kind of light that is received within a defined time window after the triggering of the measuring light source's respective light pulse.

In the case of a warning tester which is described in EP-A-0 636 266 (US-A-5,523,744) of the type mentioned at the outset, the operation of the test light transmitter takes place with the aid of a light receiver which is further arranged in the warning tester, which when receiving a light pulse in the measuring light source triggers the test light source. As the additional light receiver, due to the aforementioned shielding of the measuring chamber, cannot receive the light pulses in each relative position of the warning tester towards the warning device, but only in specific positions, this warning tester is equipped with positioning means which ensure that the warning tester in the test position is always placed in the same position in relation to

the whistleblower.

In this position, the measuring light sources and the warning tester's additional light receiver as well as the test light source and the measuring light receiver occupy defined relative positions, where it is ensured that the light pulse of the measuring light source hits the additional light receiver and the light flash of the test light source hits the measuring light receiver. As the positioning means require the presence of corresponding guiding means on the smoke detectors, this warning test can only be used for a specific type and cannot in principle be used on detectors without such guiding means.

The task of the invention is to provide a warning tester which functions flawlessly in any position in relation to the warning device to be tested, and which is thus universally applicable and can be easily adapted to the various warning types.

According to the invention, this task is solved by the adapter having a detector which reacts to an electromagnetic field which is generated by means of the measuring light source's current pulses and which controls the test light source.

With the warning tester according to the invention, is thus detected

no longer the light pulses emitted by the measuring light source as such, but the electromagnetic field generated by means of the current pulses that trigger the light pulses. As this field surrounds the detector on all sides and is relatively homogeneous, the warning tester can detect the light pulses in any direction in relation to the detector.

A first preferred embodiment of the device according to the invention is characterized in that said detector is formed by an induction coil.

A second preferred embodiment of the device according to the invention is characterized in that the adapter has a prismatic, box-like shape and, like a remote control, can be directed towards the smoke detector to be tested or adjusted towards the top of a smoke detector which is on a base.

A third preferred embodiment of the device according to the invention is characterized in that the adapter has a rotationally symmetrical shape similar to a box which is open at one end and can be placed on or pushed over the detector to be tested, and that the induction coil is arranged on the inside of the adapter. The induction coil is preferably arranged near the edge of the adapter's open side or on the bottom opposite the open side.

A fourth preferred embodiment of the device according to the invention is characterized in that there are means for reflection of the test light pulses into the measuring chamber. These means for reflection of the test light pulses, which of course can also be means for spreading them, ensure that at any position of the warning tester in relation to the alarm, a sufficient proportion of the test light pulses is directed into the measuring chamber and reaches the measuring - the light receiver.

A fifth preferred embodiment of the device according to the invention is characterized in that the said means for reflecting the test light pulses are formed by means of a reflective layer which is arranged on the inner side of the adapter.

The warning tester according to the invention can in principle be used for testing any stray light warning devices so that the relatively expensive test gas usually used for warning testing can be bypassed. This not only provides a cost saving, but also enables significantly faster testing of entire alarm lines, because each alarm immediately after testing is fully functional and is not, as in testing with test gas, equipped with a measuring chamber filled with test gas and thus it blocks further testing with follow-up alarms.

The two embodiments of the adapter, either as a small box in the form of a remote control, or as a box that can be placed on or pushed over the detector, can have different applications. The box shape is preferably used where detectors mounted on a ceiling are to be tested, which takes place from the floor of the respective room. In this case, the adapter is built into a hood-shaped housing that is attached to a pipe connection that can be repositioned using an extension pipe.

The adapter in the form of a remote control is preferably used in test laboratories where the detectors to be tested are not mounted on the ceiling but on a plate or a test table, or for detectors that are mounted inside appliances or exhaust ducts that are difficult to access for box-shaped adapters.

A further preferred embodiment of the device according to the invention is characterized by an electronic coupling for synchronizing the triggering of the test light pulses with the light pulses of the measuring light source, which coupling is provided with a step to fade out pulse noise from the signal delivered from the induction coil, which contains an amplifier and an electronically regulated voltage divider, whereby the amplifier's working point is automatically shifted in such a way by means of the regulated voltage divider that the pulse noise is blinded out and the measuring pulses caused by the pulses of the measuring light source can be recognized without error.

In the following, the invention will be explained in more detail with the help of an exemplary embodiment in the drawings; there shows

fig. 1 a schematic representation of the warning tester according to

the invention; and

fig. 2 a block core of the link for synchronization of

the measuring and test light source.

As shown in fig. 1, the warning tester serves as a functional check of smoke detectors on site, i.e. usually detectors that are mounted on the roof of a room, and is for this purpose designed so that it can be switched on from below or pushed over the detector to be tested. The warning tester is particularly suitable for warning devices whose housing approximates the shape of a ball-cap or a truncated cone. Such notifiers are shown e.g. in the international pattern registrations DM/028 534 and DM/034 103. This reference is not to be understood as a limitation on the aforementioned notification types; of course, the warning tester according to the invention can, with any small adaptations, be used with practically all modern stray light smoke detectors.

As shown, the warning tester essentially consists of a rotationally symmetrical, open on one side, box-shaped adapter 1, of an induction coil 2 which is arranged on the inner side of the adapter 1, of a light source 3 which is arranged at a negligible distance in front of the edge of the adapter 1 on the open side, and of an electronics 4 which is arranged at the bottom of the adapter. The induction solar coil 2 can, as shown in the figure, be arranged on the bottom of the adapter 1 or also on its upper edge,

e.g. at the level of the light source.

As shown in the figure for a scattered light smoke detector M, which is indicated in section, the warning tester is pushed or possibly placed on the detector to be tested. For a more detailed description of the smoke detector M, reference is made to EP-A-0 636 266, EP-A-0 821 330 and the stray light detector from the "AlgoRex" range (trademark registration for Cerberus AG).

The smoke detector M is equipped with a measuring chamber 5 which is shielded from light from the outside, a measuring light source 6 and a measuring light receiver 7, whose optical axes are mutually bent at an angle and cross each other in a central area in the measuring chamber 5. The measuring light source 6 sends short intensive light pulses into the central area of measuring chambers 5, so that no light rays can reach on the direct path from the measuring light source 6 to the measuring light receiver 7 due to the chosen device. Thus, the latter indeed "sees" the aforementioned central area in the measuring chamber 5, but cannot see the measuring light source 6. The light of the measuring light source 6 is spread with the smoke that penetrates the measuring chamber 5, and part of this stray light falls on the measuring light receiver 7.

As the measuring chamber 5 must be designed so that smoke can penetrate, the light shielding of the measuring chamber cannot be complete either, so that one must expect a proportion of extraneous light within the measuring chamber 5, even if it is very small. In order to switch off any disturbing effects of this residual extraneous light, the detector's M evaluation electronics are designed so that the measuring light receiver 7 only reacts to the scattered light received from there, when this occurs there within a certain time interval after the emission of a light pulse from the measuring light source 6. The emission of a light pulse from the measuring light source 6 thus opens a time window in the evaluation electronics so that only the receiver signals that are generated within this time window are processed by the measuring light receiver 7.

During functional testing of the smoke detector M, which is to be carried out by the warning tester shown, the light pulses of the measuring light source 6 are superimposed with intermittent light from the warning tester's light source 3, which is referred to below as the test light source. These test light pulses reach down to the measuring chamber 5 of the smoke detector M and in this to the measuring light receiver 7; after receiving one or more test light pulses, an alarm is triggered in the detector M, which is registered with the detector's alarm indicator or in the assigned signal centre. This alarm triggering serves as a criterion for the detector to be functional.

In order to ensure that in any direction of the warning tester in relation to the smoke detector M, the greatest possible proportion of the test light pulses is directed into the measuring chamber 5 to reach the measuring light receiver 7, a strip-shaped area on the inner wall of the warning tester can be tested -the light source's 3 level must be provided with a reflective coating 8.

The induction coil 2 detects the electromagnetic field generated by each light pulse from the measuring light source 6 and controls the test light source 3 so that it emits test light pulses within the aforementioned time window. For the collimation of said electromagnetic fields on the induction coil 2, the latter is surrounded by an upwardly open metallic cylinder 9 which can be covered on its front side by an electromagnetically permeable foil 10. However, the foil can also be arranged above the cylinder 9.

The adapter 1 is built into a hood-shaped housing 11 which is placed on a sleeve 12. In the latter, a pipe socket 13 is arranged onto which an extension pipe can be pushed. With several of these extension pipes which are interconnected by means of pipe brackets, the detectors can be tested up to a room height of approx. 7 m. The warning tester's power supply is either by batteries or by a mains cable, as the battery holder or the net part is arranged on the bottom laying pipe. This box-like device part, which also contains a switch for switching the warning tester on and off, is shown in fig. 1 be sign with BF. The housing 11 can, by means of the pipe connection 13, also be connected via a fork-shaped adapter (not shown), as is the case with the warning testers for the aforementioned AlfoÆex alarms.

Fig. 2 shows a block core of the coupling 4 which is connected to the adapter 1 containing the induction coil 2, which serves to synchronize the test light source 3 with the measurement light source 6. As shown, the coupling 4 contains a first preamplifier stage 14 connected to the induction coil 2, a high- and low-pass filter 15 connected there, a second pre-amplifier stage 16 connected to the filter 15, an end-stage 17 connected to the last-mentioned, and a two-way cooperating stage 18 for pulse noise suppression and automatic gain control. On the final stage 17, an active time filter 19 is connected and on this a difference judgment. After the differential judgment 20, a step 21 is connected to generate the electrical pulse for triggering the test light pulse and a voltage converter 22 which is arranged in front of the test light source 3. The voltage converter is preferably arranged in the apparatus part BF (fig. 1).

The test light source 3 is created using a flash lamp or a flash tube, e.g. a Xenon tube, and the voltage converter 22 serves to provide the voltage necessary to light the flash lamp. The voltage converter 22 is provided with a connection 23 to the final stage to suppress flash disturbances.

The measuring light source 6 (fig. 1) which is formed e.g. using an infrared diode, emits at regular intervals of e.g. 1 to 3 seconds, a light pulse so that a voltage pulse MP is induced in the induction coil 2, which is hereinafter referred to as the measuring pulse, with a duration of approximately 100 µs. This measurement pulse is very small and amounts to a few millivolts.

Of course, voltage pulses are not only induced in the induction coil 2 by means of the pulses of the measuring light source, but also by various communication currents on the warning lines. The measuring pulses MP differ from this pulse noise denoted by SP essentially by their clearly lower frequency and by their duration. The voltage pulses induced in the induction coil 2 are amplified in the first preamplifier stage 14, and then the coarsest pulse noise is filtered in the high/low pass filter 15.

After further amplification in the second preamplifier stage 16, the signal reaches the final stage 17 and into the stage 18 for pulse noise suppression and automatic gain control. In this stage, which essentially contains an amplifier, an electronically regulated voltage divider and a storage capacitor, the measurement pulses MP and the pulse noise SP are shifted at different sides relative to the zero line by means of a shift (offset) of the amplifier's operating point at the adjustable resistance, as shown the measuring pulses MP are shifted into the negative area and the pulse noise SP into the positive area. In this way, the pulse noise SP can simply be faded out. With the help of the voltage divider, there is an automatic regulation of the gain.

After fading out the pulse noise SP in step 18, the final step 17 has a measurement pulse MP at its disposal, which is formed by a characteristic double pulse and is mostly cleaned of pulse noise, which has a steep flank rise which is used in the following to trigger the flash (test -light pulse) in the test light source 3.

Because it cannot be ruled out that the output signal of the final stage 18 is still contaminated with pulse noise, a further smoothing and damping of any disturbances still present takes place in the active time window 19, whereby the measuring pulse MP takes on the saw-tooth shape shown. The flash is triggered when the measuring pulse MP exceeds a certain threshold value. To prevent the flash from being triggered by a pulse noise that is still present, the threshold value must not be too low; on the other hand, it should also not be too high so that it can also be triggered by weaker light pulses of smaller measuring pulses that correspond to the measuring light source. As shown, the threshold value mentioned and denoted by SW is placed in the difference value step 20 in the middle of the flank rise.

If the threshold value SW is exceeded due to the edge rise of the measuring pulse MP, a pulse is generated in step 21 for triggering the test light source (flash lamp) 3. This pulse has the shown rectangular shape and preferably lasts somewhat longer than the measuring pulse MP, e.g. about. 20 us.

The suppression of flash disturbances, which serves to suppress the disturbing influence of the flash from the test light source 3 on the gain regulation, because this does not function as desired for a short time after the flash is triggered, consists in the regulation in step 18 being blocked for the duration of the flash .

Alternatively to the one in fig. In the shape shown in 1, the adapter can also have the shape of an oblong prism similar to a remote control for electronic devices or for door openers for garage doors. Such an adapter is preferably used when testing smoke detectors in laboratories or in hard-to-reach appliances or exhaust ducts. For testing detectors, this adapter is either aimed at the detectors at a short distance from them, or the adapter is placed on top of the detectors when they are placed with the top upwards on a horizontal plate or a horizontal table. At this position of the adapter, practical tests have shown that even with detectors with a straight "top", the test light pulses sent out from the test light source reach the measuring light receiver, which is obviously caused by scattering of the test light pulses by particles which is in the room air.

The adapter contains, on the end which faces the detector to be tested during the test, an emission window for the flow of the test light pulses, as well as an infrared filter for these so that light flashes no longer have a disturbing effect.

Claims (12)

1. Device for testing the function of stray light smoke detectors (M) which is equipped with a measuring chamber (5) with a measuring light source (6) that emits light pulses, and a measuring light receiver (7), with an adapter (1 ) which contains a test light source (3) which is operated synchronously with the light pulses of the measuring light source, in order to influence the measuring light receiver (7) with test light pulses, characterized in that the adapter (1) has a detector (2) which reacts to an electromagnetic field which is generated by means of the current pulses of the measuring light source (6) and which controls the test light source (3). 2. Device as stated in claim 1, characterized in that said detector is formed by an induction coil (2). 3. Device as specified in claim 1 or 2, characterized in that the adapter has a prismatic, box-like shape and, like a remote control, can be aimed at the smoke detector (M) to be tested or adjusted towards the top of a smoke detector that is on a surface. 4. Device as specified in claim 3, characterized in that the adapter contains, on the end which during testing faces the detector (M) to be tested, a window for the flow of the test light pulses, as well as an infrared filter for these. 5. Device as stated in claim 1, characterized in that the adapter (1) has a rotationally symmetrical shape similar to a box which is open at one end and can be placed on or pushed over the detector (M) to be tested, and that the induction coil (2) is arranged on the inside of the adapter (1). 6. Device as stated in claim 5, characterized in that the induction coil (2) is arranged near the edge of the open side of the adapter (1) or on the bottom opposite the open side. 7. Device as stated in claim 5, characterized in that means (8) are arranged for reflection of the test light pulses into the measuring chamber, and that these means are formed by means of a reflective layer (8) which is arranged on the inside of the adapter (1) . 8. Device as stated in claim 7, characterized in that the test light source (3) is arranged near the edge on the open side of the adap ter (1) and the reflective layer (8) are formed by means of a strip-shaped area which is next to the said edge. 9. Device as stated in claim 6, characterized in that the bottom part of the adapter (1) containing the induction coil (2) is covered by means of a foil (10). 10. Device as stated in claim 1, characterized in that the test light source (3) is formed by a flash lamp. 11. Device as stated in one of claims 3 to 10, characterized by an electronic coupling (4) for synchronizing the triggering of the test light pulses with the light pulses of the measuring light source (6), which coupling (4) is provided with a stage ( 18) in order to block out pulse noise (SP) from the signal delivered from the induction coil (2), which contains an amplifier and an electronically regulated voltage divider, whereby such a shift of the amplifier's operating point automatically occurs by means of the regulated voltage divider that the pulse noise (SP) is blinded out and the measurement pulses (MP) caused by the pulses of the measurement light source (6) can be recognized without error. 12. Device as stated in claim 11, characterized in that during the duration of each test light pulse, the regulation of the step (18) is blocked in order to fade out pulse noise.